Cannabis Grow

It was important to “beef up cessation services in a comprehensive way so that it is relevant to the communities that are most affected” . The flip side of including menthol in policies banning sales of flavored tobacco products to address the health of African Americans and other targeted populations such as the LGBT community, was fear within those communities about criminalizing smoking and smokers. Numerous participants emphasized that flavor policies were “not about the behavior but about sales of the product. We’re not about policing people’s behavior. We don’t want to see any more negative police/community interaction” . Most participants believed flavor bans were unlikely to result in over-policing: “I…don’t think we’re going to see…this law be misused to justify inappropriately criminalizing residents” . Another participant remarked that the argument was raised because “the tobacco industry has…paid some African American leaders to come out and say [bans on sales of menthol products] were criminalizing the Black community” . However, she also pointed out that she wasn’t sure what would happen “if an officer sees somebody selling some [contraband menthol cigarettes] New ports out of their trunk…I would like us to get a handle on [that] before we have an Eric Garner case in California” . Many participants showed awareness that their policies were precedents for other jurisdictions to follow . An advocate reported that a jurisdiction implementing a novel ordinance helps “a lot of people [in other cities] to understand that this is the next big step that can be taken” in their own community .

Even if a policy change did not seem to have a short term impact, one participant said, “we really have to take the long view,plant grow table that we’re creating a flavor-free tobacco region and state…so that youth [eventually] wouldn’t be able to go across the street into the next town and buy these products” . Participants also exhibited awareness that policy innovation in California generally had cities and counties taking the lead, not state government. Asked whether the state’s new endgame focus had influenced his work, one participant replied, “I think our local work has shifted the conversation of the state, to be honest” . Another noted that his organization “always had that vision…even before the state wanted that endgame” . This local, then state adoption of policy change was normal, as another participant noted: “the idea [is] they grow from the local jurisdictions to make statewide implementation more likely” . That influence could spread not only through the state, but also to other states and from there, “ripple out into the rest of the world” . A couple of participants sounded a warning about this process. One commented that, once policy making started to move forward at the state level, “We need to be very vigilant of preemption,” . Another was concerned that state-level action would skip over the community work necessary to make policies acceptable and successful, particularly among communities of color: “You ban flavored tobacco and menthol, and…where’s the community engagement?…There can’t be one without the other or there’s going to be imbalance” between policymakers and those most affected by regulations . Several participants also noted a greater readiness that they had seen in even the recent past for new, innovative policies. One noted this conceptual transition, saying, “To think about the endgame at first was kind of jarring . . .[but after Beverly Hills] you start to think, wow, maybe this is possible!” . Another said of his local elected officials, “They wanted a bolder move…They wanted things like, ‘what is the way to end this?…How do we stop this?’” This was a big change, he noted. “There wasn’t a conversation even happening…And that was just the last couple of years” . An advocate from another area reported that, “I’ve heard elected officials say…‘We’re saying we won’t allow pharmacies to sell tobacco anymore. Well, can’t we just say that nobody sells tobacco anymore?’” . One participant saw her role as getting people to believe an “endgame” was possible, saying: “Let’s believe [in zero smoking prevalence], and then we can work towards how we’re going to get there” . Creating an endgame vision and overcoming skepticism seemed increasingly possible in California, as one advocate noted: “the entire United States is learning a lot from California, and I think putting those big goals in front of public health advocates is really making a huge difference, and believing it will happen is making a big difference.

The policies we now consider, and we would have considered impossible, even just two years ago, now people are taking as commonplace” .Previous research [5] in 2018 found that California legislators and advocates to be somewhat cautious about endgame-oriented policies, preferring more gradual approaches. This study found an overall sense from interviewees of momentum for policy innovation, with greater belief in the possibility of an endgame. Some of this may be a response to advocates’ having begun to receive funding from the state’s new tobacco tax, enacted in 2016, that enabled local tobacco control agencies and coalitions to hire staff and engage in more ambitious policy-oriented planning. Advocates likely understood the success of the tax as signaling public support for tobacco control efforts in the state. The influx of funding and resources from the tax increase may have also bolstered advocates’ enthusiasm. The greater caution about endgame policies found in previous research may also relate to the specific participants. The previous study included interviews with state legislators and leaders of statewide organizations; the current study prioritized local advocates . Statewide leaders – and particularly members of the state legislature — think in terms of what can be accomplished at the state level,hydroponic table taking into account that law must get support from legislators who represent communities on a wide spectrum of readiness for policy change. The local advocates knew that their localities could take bolder steps, and judged that they would be willing to do so again. Participants understood that there were challenges ahead, for example, framing the endgame in such a way as to avoid or undercut arguments made in the past by the tobacco industry and its allies. For example, participants did not feel that the history of alcohol prohibition in the US was an appropriate reference for the tobacco endgame, but understood that it would be important to make that distinction, notably by distinguishing sales bans from prohibitions on possession or use of tobacco products. Making that distinction was also important to establish that new tobacco control policies would not invite further over policing of marginalized communities, such as occurred in the Eric Garner case. Another challenge that participants foresaw was California’s recent legalization of marijuana for recreational use.

Although there was some concern that the liberalization of marijuana regulation suggested that public opinion would not favor stricter tobacco policy, most participants had a more nuanced perspective—that one could simultaneously favor restricting tobacco sales, especially to youth, while permitting sales of marijuana, especially to adults. The combined use of tobacco products and marijuana meant that policies had to encompass both. Further, some participants proposed that the stricter rules relating to marijuana retail sales could provide a model for tobacco. Participants demonstrated awareness that policy innovations carried risks. Although they identified policies containing exemptions as less than ideal, requiring more complex and expensive enforcement or a difficult amendment process, participants sometimes considered exemptions to be a pragmatic way of advancing a policy; this was true even in the case of a policy traditionally considered so far from being considered “pragmatic” as to be almost unthinkable, a tobacco sales ban. In some cases, participants considered exemptions to be harmful. For example, a flavor ban that exempted menthol “solved” the problem by removing the products most obviously marketed to children and youth. However, it left African Americans still vulnerable, and without the allies concerned about youth-oriented “candy” flavors. There appeared to be broad understanding that the goal of ending the epidemic “for all population groups,” meant increased engagement with communities with the highest levels of tobacco use. The trend of California tobacco control policy efforts, led by localities, then followed at state level, was well known to participants. Some suggested that the state’s new focus on a tobacco endgame was the result of local innovation. Participants also recognized that communities took their cues from others, so that policy innovations even in small communities would “ripple outward” and engender wider effects over time. Our study has limitations. We interviewed a small number of key informants selected because they worked in communities that had recently passed innovative tobacco control policies; thus, our sample cannot be considered representative of all California tobacco control advocates. Those working in more conservative communities may view the idea of an endgame more skeptically. However, other tobacco control policies , were once regarded as radical and became more normative with their adoption. Indeed, during the course of the study, Beverly Hills began discussing the first-ever prohibition on sales. Some participants interviewed before these deliberations found such an idea out of reach, while others, interviewed afterward, remarked that the conversation alone made such policies seem possible. Discussions of the tobacco endgame have frequently focused on complex and drawn-out plans, sometimes involving sizable state investment, such as the proposal that the state should buy out the tobacco industry. Recent events in California suggest a different, in many ways a simpler future, more in line with the history of tobacco control, in which localities have taken the lead. The first laws in California calling for non-smoking sections in restaurants were local and largely symbolic, but they demonstrated the possibility for clean indoor air, and more, and stronger laws followed. A tobacco sales ban in a small municipality such as Beverly Hills will not substantially reduce tobacco use in California, but it serves as proof of concept. Municipalities and counties in the U.S. may increasingly recognize and exercise their ability to pass such laws, as the 2014 U.S. Surgeon General’s report suggested. This study, and the recent, rapid spread of policies to ban sales of flavored tobacco products in the state, suggest that tobacco control advocates in California are attentive to such possibilities and willing to act. This study, and the history of California’s approach to tobacco control more generally, point to the importance of local policy advocacy. Local advocates understand the specific issues in their communities, and have a nuanced perspective on policy development, such as when exemptions or exceptions are and are not acceptable. Local advocates also may be able to implement policies that would not be possible at a state or national level; such policies may seem radical, but passage normalizes them. Not every community is ready, but this study suggests that we should encourage more attention to the local actors and new, small-scale policy changes happening around the world that have the potential to ultimately end the tobacco epidemic. Acknowledgement: Support for this paper was provided by the California Tobacco Related Disease Research Program, Grant 26IR-0003. Cigarette smoking causes and exacerbates chronic obstructive pulmonary disease and asthma,1 and is associated with wheezing and cough in populations without a respiratory diagnosis.While the relationship between cigarette smoking and respiratory symptoms is well-established, the relationship between use of other tobacco products besides cigarettes and respiratory symptoms in adults is less clear. Changes in the tobacco market, in part, reflect efforts to market products that may cause less harm than cigarettes. Electronic nicotine delivery devices may represent such a product. With respect to respiratory symptoms, findings have been mixed, however. Numerous animal and in vitro studies raise theoretical concerns about e-cigarette use and lung disease.Short term human experimental studies have linked adult e-cigarette use with wheezing and acute alterations in lung function,and lower forced expiratory flow.One longer term 12-week prospective study of cigarette smokers switching to e-cigarettes found no effects on lung function,and two 1-year randomized controlled clinical trials found reduced cough and improved lung function in persons who used e-cigarettes to reduce or quit cigarettes.

Elucidating the role of macro- and neighborhood-level exposures in adolescent psychotic experiences could be particularly informative for early intervention efforts, because the clinical relevance of psychotic phenomena increases later in adolescence.Cities have higher rates of violent crime and tend to be more threatening and less socially cohesive.Additionally, 16–24 year-olds in the United Kingdom are 3 times more likely than other age groups to be victimized by a violent crime.Therefore, many adolescents raised in cities are not only embedded in more socially adverse neighborhoods, but are also more likely be personally victimized by crime compared to other age groups and peers living in rural neighborhoods. Given that cumulative trauma is implicated in risk for psychosis,we hypothesized that one of the reasons that young people in urban settings are at increased risk for psychotic phenomena is that they experience a greater accumulation of neighborhood-level social adversity and personal experiences of violence during upbringing. No study has yet explored the potential cumulative effects of adverse neighborhood social conditions and personal crime victimization on the emergence of psychotic experiences during adolescence. The present study addresses this topic with data from a nationally-representative cohort of over 2000 British adolescents, who have been interviewed repeatedly up to age 18, with comprehensive assessments of victimization and psychotic experiences and high-resolution measures of the built and social environment. We asked: Are psychotic experiences more common among adolescents raised in urban vs rural settings? And does this association hold after controlling for neighborhood-level deprivation,vertical rack as well as individual- and family-level factors, that might otherwise explain the relationship? Can the association between urban upbringing and adolescent psychotic experiences be explained by urban neighborhoods having lower levels of social cohesion and higher levels of neighborhood disorder ? 

Are psychotic experiences more common among adolescents who have been personally victimized by a violent crime? And Is there a cumulative effect of neighborhood social adversity and personal crime victimization on adolescent psychotic experiences? In addition, the present study conducted sensitivity analyses using adolescent psychotic symptoms as the outcome .We conducted analyses following 5 steps. First, logistic regression was used to test whether psychotic experiences were more common among adolescents raised in urban neighborhoods. We controlled for family- and individual-level factors and for neighborhood-level deprivation to check that the association was not explained by these characteristics which could potentially differ between urban vs rural residents. We also examined the association between urbanicity and adolescent major depression to check for specificity of the previous findings. Second, because urban neighborhoods are characterized by lower levels of social cohesion and higher levels of neighborhood disorder we tested whether levels of these neighborhood characteristics accounted for the association between urbanicity and adolescent psychotic experiences, and we also estimated the separate associations of social cohesion and neighborhood disorder with adolescent psychotic experiences. Third, using logistic regression we checked whether adolescents who had lived in the most socially adverse neighborhoods were more likely to be personally victimized by violent crime and, in turn, whether psychotic experiences were more common among adolescents who had been victimized. Fourth, using interaction contrast ratio analysis we investigated potential cumulative and interactive effects of adverse neighborhood social conditions and personal victimization by violent crime on adolescent psychotic experiences. Four exposure categories were created for this analysis by combining neighborhood social adversity with personal crime victimization . Finally, sensitivity analyses were conducted using the clinically-verified adolescent psychotic symptoms as the outcome measure. All analyses were conducted in STATA 14.2 , and accounted for the non-independence of twin observations using the “CLUSTER” command.

This procedure is derived from the Huber-White variance estimator, and provides robust standard errors adjusted for within cluster correlated data.Note: ordinal logistic regression was used in analyses where adolescent psychotic experiences was the dependent variable, because this was on an ordinal scale.This study investigated the role of urbanicity, neighborhood social conditions, and personal crime victimization in adolescent psychotic experiences and revealed 3 initial findings. First, the association between growing up in an urban environment and adolescent psychotic experiences remained after considering a range of potential confounders including family SES, family psychiatric history, maternal psychosis, adolescent substance problems, and neighborhood-level deprivation. This association between urbanicity and psychotic experiences was explained, in part, by 2 features of the neighborhood social environment, namely lower levels of social cohesion and higher levels of neighborhood disorder. Second, personal victimization by violent crime was nearly twice as common among adolescents in the most socially adverse neighborhoods, and adolescents who had experienced such victimization had over 3 times greater odds of having psychotic experiences. Third, the cumulative effect of neighborhood social adversity and personal crime victimization on adolescent psychotic experiences was substantially greater than either exposure alone, highlighting a potential interaction between these exposures. That is, adolescents who had lived in the most adverse neighborhood conditions and been personally victimized were at the greatest risk for psychotic experiences during adolescence. The present findings extend previous evidence from this cohort implicating childhood urbanicity and neighborhood characteristics in the occurrence of childhood psychotic symptoms.Here we show that the effects of urban and socially adverse neighborhood conditions on psychotic experiences are not limited to childhood, but continue into adolescence when psychotic phenomena become more clinically relevant.These findings support previous evidence demonstrating higher rates of psychosis-proneness and prodromal status among adolescents and young adults in urban,threatening,and socially fragmented neighborhoods.

Late adolescence heralds the peak age at which psychotic disorders are typically diagnosed.If a degree of aetiological continuity truly exists between adolescent psychotic experiences and adult psychotic disorder, ours and other recent findings tentatively support a mechanism linking adverse neighborhood conditions during upbringing with psychosis in adulthood. In our study,microgreen flood table the combined effect of adverse neighborhood social conditions and personal victimization by violent crime was greater than the independent effects of each. This is consistent with cumulative stress models and previous studies showing that risk for psychosis phenotypes increases as the frequency and severity of stressful exposures increase.Several biological and psychological mechanisms could explain why adolescents who were exposed to neighborhood social adversity and violent crime during upbringing were more prone to psychotic experiences. Prolonged and acute early-life stress is purported to dysregulate the biological stress response and lead to dopaminergic sensitization, which is the leading hypothesized neurochemical pathway for the positive symptoms of psychosis.In addition, adolescents who grow up in threatening neighborhoods with weak or absent community networks could develop psychosislike cognitive schemas such as paranoia, hypervigilance, and negative attributional styles.A cognitive pathway could explain why effects were apparent for psychotic experiences but not major depression. Our findings tentatively suggest a mechanism whereby childhood exposure to neighborhood social adversity sensitizes individuals to subsequent stressful experiences such as crime victimization. This hypothesized mechanism is supported by recent evidence of neurological differences in social stress reactivity between adults with urban vs rural upbringing.Further research into the influence of neighborhood exposures on childhood neurocognitive development could shed light on this hypothesized mechanism.Several limitations should be considered. First, causality of findings from this observational study cannot be assumed. Noncausal mechanisms, such as the selection of genetically high-risk families into urban and adverse neighborhoods, remain possible,though our findings were not explained by proxy indicators of genetic and familial risk. Second, neighborhood conditions were measured approximately 5 years before adolescent psychotic experiences were assessed. However, the vast majority of adolescents reported that they did not move house between ages 12 and 18. Third, though crime victimization was more common in adverse neighborhoods, we do not know the extent to which these victimization experiences occurred outside the home. Perpetrators of physical violence are often family members,suggesting that our measure of violent crime captured victimization inside as well as outside the home. Fourth, psychotic experiences are associated with adult psychosis but also with other serious psychiatric conditions; while a degree of specificity was suggested in that the effect of urbanicity on psychotic experiences was not replicated for adolescent depression and was not explained by adolescent substance problems, it is probable that the mental health implications of growing up in an urban setting extend beyond psychosis.

In addition, associations arising for the clinically-verified psychotic symptoms were often non-significant. It is possible that the low prevalence of psychotic symptoms in this sample restricted our power to detect associations. However, it is also possible that the self-report measure of adolescent psychotic experiences captured genuine experiences as well as psychotic phenomena . This may have inflated the associations arising for adolescent psychotic experiences, though it is reassuring that point estimates were fairly similar to those produced for psychotic symptoms. Finally, our findings come from a sample of twins which potentially differ from singletons. However, E-Risk families closely match the distribution of UK families across the spectrum of urbanicity and neighborhood level deprivation.Furthermore, the prevalence of adolescent psychotic experiences among E-Risk participants is similar to non-twin samples of adolescents and young adults.Acute pancreatitis is an acute, inflammatory, potentially life-threatening condition of the pancreas. With over 100000 hospital admissions per annum, acute pancreatitis is the leading gastrointestinal cause of hospitalization in the United States and the 10th most common non-malignant cause of death among all gastrointestinal, pancreatic, and liver diseases . It is a major cause of morbidity and healthcare expenditure not only in the United States, but worldwide. There are numerous established etiologies of acute pancreatitis, among which gallstones and alcohol are the most common. The remaining cases are primarily attributable to the following etiologic factors: Hypertriglyceridemia, autoimmune, infection, hyper/hypocalcemia, malignancy, genetics, endoscopic retrograde cholangiopancreatography, and trauma. Despite accounting for approximately only 1%-2% of cases overall, drug-induced pancreatitis has become increasingly recognized as an additional and vitally important, albeit often inconspicuous, etiology of acute pancreatitis. The World Health Organization database lists 525 different medications associated with acute pancreatitis.Unfortunately, few population-based studies on the true incidence of DIP exist, limiting knowledge of true incidence and prevalence. In this setting, we review the ever-increasing diversity of DIP, with emphasis on the wide range of drug classes reported and their respective pathophysiologic mechanisms – in an attempt to raise awareness of the true and underestimated prevalence of DIP. We hope this manuscript will aid in increasing secondary prevention of DIP ultimately leading to a decrease in overall acute pancreatitis-related hospitalizations and economic burden on the health care system. As there is no standardized approach to stratifying patients to determine their risk of developing acute pancreatitis, primary prevention for the majority of etiologies cannot be fully implemented. Secondary prevention of acute pancreatitis, on the other hand, can more easily be executed. For example, abstinence from alcohol reduces the risk of alcoholic pancreatitis, cholecystectomy reduces the risk of gallstone pancreatitis, and tight control of triglycerides reduces the risk of recurrent episodes of pancreatitis secondary to hypertriglyceridemia. On this notion, unique to DIP, is the fact that it can be prevented in both the primary and secondary fashion. Unfortunately, however, most of the available data in reference to DIP is derived from case reports, case series, or case control studies. In this vein, the causality between specific medications and acute pancreatitis has been established in only a minority ofcases. In addition, oftentimes, lack of a known etiology for acute pancreatitis directly increases length of hospitalization due to delayed diagnosis and subsequent treatment. Moreover, patients unaware of an adverse drug reaction to a prior medication may continue taking that medication leading to repeat hospitalizations. Finally, with the rapid expansion of pharmacologic agents, widespread legalization of cannabis, increase in recognized medications, supplements, and alternative medications reported to induce pancreatitis, the need to become familiar with this esoteric group remains imperative, and knowledge in the form of awareness regarding certain medications is warranted.First, the lack of mandatory adverse drug reporting systems allow many cases to go unreported. Second, bias exists, in the sense that clinicians tend to forgo linking unusual medication suspects to a rare adverse event. Third, it is often difficult to rule out other, more common, causes of drug-induced pancreatitis, especially in patients who have multiple comorbidities and underlying risk factors. Fourth, many cases lack a re-challenge test or drug latency period to definitively link acute pancreatitis to a particular drug. Finally, evidence is lacking to support the use of any serial monitoring technique – namely, imaging or pancreatic enzymes to help detect cases of drug-induced pancreatitis.

The MACH 14 cohort is a dataset pooled from 16 studies conducted at 14 sites across 12 states. Each study in MACH14 used electronic data monitoring pillcaps to objectively measure participants’ adherence to antiretroviral medication. The focus of this study was on non-methadone substance abuse treatment so studies conducted in methadone maintenance programs were not considered in this analysis. From the 1579 participants in the MACH14 dataset, we identified 215 from two studies based outside methadone clinics because only these two studies’ participants had both EDM and substance abuse treatment status data. Written informed consent was obtained for participation in the parent studies, and the Yale Institutional Review Board approved the secondary analyses. Patients were asked about engagement in substance abuse treatment and use of specific substances for varying preceding time frames: one of the two studies asked about participation in substance abuse treatment during the past 90 days and use of specific substances over the past 30 days, while the other study asked about treatment over the past 30 days and substance use over past 14 days. To aggregate substance use data across studies, variables representing use of specific substances were defined as the proportion of days within the asked-about time frame the person had used each of several substances. This analysis used data collected at the first time point at which participants had EDM data for the preceding four weeks, had also been asked about being recently enrolled in substance abuse treatment, and were not enrolled in a methadone-clinic-based study. To estimate the effect of substance abuse treatment on adherence, adherence was calculated for the four weeks up to and including the date recent substance abuse treatment enrollment was assessed,grow rack as well as for the four weeks after the substance abuse treatment determination. Adherence in each week was calculated by dividing the weekly number of doses taken by the weekly number of prescribed doses for each medication, with adherence to each medication capped at 100%.

Adherence for a patient on multiple antire trovirals was calculated by averaging across prescribed medications.The effects of substance abuse treatment on adherence were determined in multivariate analyses that included a grouping variable denoting whether the patient was enrolled in substance abuse treatment and a variable reflecting substance abuse treatment over time. The analyses were conducted controlling for sociodemographic characteristics that might differ between patients in, and not in, substance abuse treatment. To control for the anticipated finding that patients in substance abuse treatment would have more active drug use than a reference group including people who had never had significant substance use, analyses included a measure representing the largest proportion of days during which participants had used either cocaine, opiates, or stimulants. Cannabis use was not included in this measure of illicit drug use because in a separate analysis of the MACH14 dataset and in an earlier study recent cannabis use was not associated with worse adherence. Analyses were run with SAS 9.2. The model included random effects for intercept and slope as this model had better fit to the data than models with fixed effects only.Although the analyses controlled forillicit drug use, it is possible that our self-report measures of substance use understated the impact of substance abuse treatment on substance abuse and that it is in fact abstinence that facilitates adherence. In one of the few randomized controlled studies of HIV-positive drug users in which abstinence was the target outcome, there was a trend towards a significant correlation between consecutive weeks of toxicology-tested abstinence during the intervention and reductions in viral load. There is also evidence from a naturalistic longitudinal cohort study that attendance at HIV treatment, a sine qua non for adherence, appears to improve with newly-achieved abstinence. Substance abuse treatment might improve adherence by mechanisms other than facilitating abstinence from using drugs. Substance abuse treatment typically involves case management to address the unstable housing characteristic of drug users. Stable housing arrangements during substance abuse treatment would be expected to foster adherence, in that stable routines have been associated with better adherence.

Substance abuse treatment also focuses patients on future goals, an orientation that has been described as fostering adherence, and substance abuse treatment can involve re-arranging social networks in ways that also might foster better adherence. It is possible that enrollment in substance abuse treatment reflects a lurking un-measured variable associated with both being in substance abuse treatment and better adherence. The finding of better adherence among people in substance abuse treatment was not buttressed by finding better adherence over time among patients in treatment. However, it might have been difficult to detect the time course of benefit from substance abuse treatment because the data did not specify when patients were entering, continuing, or finishing substance abuse treatment.Substance abuse was measured by self-report, and it is possible that substance abuse was disproportionately under-reported by people out of substance abuse treatment, thus exaggerating the impact of substance abuse treatment on adherence. The type of substance abuse treatment was not specified and the findings may not apply to all types of substance abuse treatment. Finally, the sample size was modest, and the number of participants in substance abuse treatment was small. It is noteworthy that although adherence decreased on average over time, the course of adherence varied significantly by person. Further analyses should test variables that may account for individual differences in adherence over time. These findings lend some support to the clinical practice of addressing substance use in an effort to improve adherence. The crucial next step is to develop and prospectively test substance abuse-focused interventions for patients with both substance abuse and adherence problems.Marijuana has been used for hundreds of years for mystical and religious ceremonies, for social interaction, greenhouse grow tables and for therapeutic uses. The primary active ingredient in marijuana is delta-9 tetrahydrocannabinol,one of some 60 21-carbon terpenophenolic compounds knows as cannabinols, which exerts its actions via cannabinoid receptors referred to as CB1 and CB2 receptors. Endogenous cannabinoids have been isolated from peripheral and nervous tissue. Among these, N-arachidonoylethanolamine and 2-arachydonoylglycerol are the best-studied examples.Behaviorally, AEA increases food intake and induces hypomotility and analgesia.

Anandamide also induces sleep in rats.Cannabinoid stimulation stabilizes respiration by potently suppressing sleep apnea in all sleep stages.In humans, marijuana and ∆9-THC increase stage, or deep, sleep.The mechanism by which the cannabinoids induce sleep is not known, hampering the development of this drug for possible therapeutic use. The sleep-inducing effects of cannabinoids could be linked to endogenous sleep factors, such as adenosine . There is substantial evidence that AD acts as an endogenous sleep factor. Extracellular levels of AD measured by microdialysis are higher in spontaneous waking than in sleep in the basal forebrain and not in other brain areas such as thalamus or cortex.Given this evidence, we hypothesized that the soporific effects of AEA could be associated with increased AD levels. In the present study, extracellular AD levels were assessed in the basal forebrain via the microdialysis method. The basal forebrain was sampled because this region is particularly sensitive to AD.The cholinergic neurons located in the basal forebrain are implicated in maintaining waking behavior, and it is hypothesized that sleep results from the accumulating AD, which then inhibits the activity of the wake-active cholinergic neurons.Our results show that systemic application of AEA leads to increased AD levels in the basal forebrain during the first 3 hours after injection, and total sleep time is increased in the third hour. These findings identify a possible mechanism by which the endocannabinoid system influences sleep.Previous reports have found that application of AEA directly to the brain increases total sleep time and SWS.We have now shown that systemic administration of AEA also has the same effect. More importantly, the increased sleep is associated with increased extracellular levels of AD in the basal forebrain. The increase in sleep induced by AEA occurred during the third hour after injection of the compound and was associated with peak levels of AD. In each of the first 2 hours, AD levels were significantly higher compared to vehicle injections, with a peak in AD occurring in the third hour. Increased sleep was not evident in the first 2 hours, suggesting that a threshold accumulation of AD might be necessary to drive sleep. In the fourth hour, AD decreased dramatically relative to the third hour, and the levels were not different from those observed after vehicle administration. There was no significant difference in delta power between AEA and DMSO, even though the percentage of SWS was higher with AEA.Sleep is hypothesized to result from accumulating AD levels, and then there is a decline as a result of sleep.

This effect is present in the basal forebrain and not in other brain areas.Thus, this purine is hypothesized to act as a homeostatic regulator of sleep; its buildup increases the sleep drive, and as AD levels decline, sleep drive also diminishes. The present data are consistent with this hypothesis in that peak sleep levels occur with peak AD levels, and then as a result of sleep, AD levels also decline . The CB1-receptor antagonist blocked the AEA-induced induction of AD as well as the sleep-inducing effect. The CB1-receptor antagonist SR141716A has been tested in diverse behavioral paradigms, and it blocks the effects induced by AEA.Santucci and coworkers demonstrated that administration of SR141716A increases W and decreases SWS.Here we replicated these effects but also demonstrated that the increase in AD levels after injection of AEA were blocked by the CB1- receptor antagonist. The AEA exerts its effect via the CB1 receptor and hyperpolarizes the neuron.The CB1 receptors are coupled to the Gi/Go family of G protein heterotrimers. Activation of the CB1 receptor inhibits adenylate cyclase and decreases synthesis of cAMP.In rats, the CB1 receptor is localized in the cortex, cerebellum, hippocampus, striatum, thalamus, and brainstem.The CB1 receptor is also present on basal-forebrain cholinergic neurons as determined by immunocytochemistry.The CB1- receptor mRNA is present in the basal forebrain.This receptor is also present in the brainstem where the cholinergic pedunculopontine tegmental region is implicated in W.Microinjection of AEA into this region decreases W and increases REM sleep.The CB1 receptors are also localized in the thalamus,an area implicated in producing slow waves in the EEG.Activation of these receptors in the pedunculopontine tegmentum, basal forebrain, and thalamus may decrease the firing of wake-active neurons, resulting in sleep. Additionally, accumulation of AD in the basal forebrain may inhibit the cholinergic neurons and also increase sleep. Direct injections of the AEA into the basal forebrain were not possible since AEA dissolves only in DMSO and alcohol. Moreover, delivery of the AEA dissolved in DMSO clogs the microdialysis membrane. The mechanism by which AEA increases AD in the basal forebrain is not known, even though both AD and AEA could directly inhibit the wake-active neurons given the inhibitory action of these agents on their receptors. Nevertheless, there is evidence of an interaction between the adenosinergic and the endocannabinoid systems.For example, the motor impairment induced by the principal component of cannabis, ∆9- THC, is enhanced by adenosine A1-receptor agonists.We now show that stimulation of the endocannabinoid system via the CB1 receptor increases AD in the basal forebrain. The endocannabinoids and AD may regulate sleep homeostasis via second and third messengers, as we have hypothesized.Previously, investigators have shown that stage 4 sleep in humans is increased in response to administration of ∆9-THC or smoking of marijuana cigarettes.We now show that such a soporific effect is associated with an increase in AD levels in the basal forebrain. Cannabinoid stimulation suppresses sleep apnea in rats,and A1-receptor stimulation also has the same effect.The endocannabinoid system also influences other neurotransmitter systems,in particular, inhibiting the glutamatergic system.It would be important to determine whether endogenous levels of specific neurotransmitter systems are changed as a result of AEA-induced activation of the CB1 receptor. Irrespective of the mechanism involved, our studies underscore the importance of endocannabinoid-AD interactions in sleep induction and open new perspectives for the development of soporific medications. The discovery of the cannabinoid receptors and endocannabinoid ligands has generated a great deal of interest in identifying opportunities for the development of novel cannabinergic therapeutic drugs. Such an effort was first undertaken three decades ago by a number of pharmaceutical industries, but was rewarded with only modest success.

The sinuses, a connected system of hollow cavities in the skull lined with mucosa tissue that has a thin layer of mucus, may help humidify air in the nasal cavity. In 2015, a $15-million grant by the National Science Foundation kicked off further research into how animals, including humans, locate the source of an odor, such as food . The research focuses on how odors move in the landscape and how animals use spatial and temporal cues to move toward a target. The research is just one part of the federal BRAIN Initiative that studies olfaction as a window into understanding the brain, because olfaction is considered the most primal pathway to understanding brain evolution. At present, such information is not available for e-nose development. The olfactory epithelium contains three types of cells: olfactory receptor neurons, their precursors and supportive cells. The cilia are constantly exposed to the nasal environment and are continually replaced, even their basal cells, possibly indicating frequent damage. A layer of mucus 10 to 40 µm thick coats the mucosa epithelium, and odorants must pass into this layer to interact with the sensory neurons through a series of poorly understood “perireceptor” events . Each sensory neuron, covered in cilia, trim tray projects down from the olfactory epithelium into the mucosa.These proteins thread back and forth across the outer membrane of the cilia and interact with odorants. Various theories have been put forward on how exactly odorants interact with the proteins, and this remains an area of research.

Receptor cells of the same type are randomly distributed in the nasal mucosa but converge on the same glomerulus. Each type of neuron frequently responds to more than one odorant, even from different chemical classes, so the overall odor signal must be integrated by the olfactory bulb . Integration includes both olfactory and trigeminal signals, and workers often report odor and irritation as a combined, singular perception . The olfactory bulb also receives information from other areas of the brain to filter out background odors and enhance perception. Fascinatingly, none of the physical stimuli themselves ever reach the brain. Instead, a host of proteins transduces captured molecules into a small change in voltage that can be deciphered by the brain . The unpleasant and pleasant aspects of mixtures are represented separately in the brain . Human sensitivity to odorants ranges across several orders of magnitude . Around 1 ppt appears to be a theoretical limit for sensitivity, and many odorants are not perceived until above 1,000 ppm. The major components of air are not sensed at all . Carbon dioxide is an interesting chemical because it is odorless at ambient concentrations yet selectively triggers only the trigeminal neurons and not the olfactory neurons when it reaches 200-fold above background levels . Describing multiple odor notes in mixtures is challenging. Fewer than 15% of the people tested could only identify one of the odorants present in a mixture, and identification of 3 to 4 components was the limit for trained experts . Even 90% of wine judges were unable to reproduce their scores . General variability in odor perception is high. Factors include age, sex, lifestyle, prior exposures, culture and health status . Approximately 3% of Americans have minimal or no sense of smell .Prolonged or repeated exposure to an odor can lead to a decreased response , which has the benefit of allowing a baseline reset in preparation for a new stimulus . Habituation happens as quickly as 2.5 second and is accompanied by decreased transduction by the neurons after 4 seconds . A growing field of research throughout public health is the microbiome, the microflora that contribute to gut, mouth and skin health. The nasal cavity, too, hosts microbes that contribute to normal functioning .

Some microbes themselves emit odorants and can decrease the host’s sensitivity . Attempts to reverse engineer an odor based on the molecular properties of the odorant have been successful. Algorithms were able to predict the odor note of a given odorant based on its chemoinformatic features for 8 descriptors out of 19 total . Researchers using systems biology and computational techniques mapped odors to specific proteins on olfactory receptor neurons, which was dubbed the “odorome” . Risk assessment for estimating the non-sensory health risks of airborne chemicals has a large body of guidance and case studies. The primary focus of this paper is on the sensory health effects of odors that integrate both trigeminal response and olfactory response . In general, the olfactory pathway iscapable of informing the organism about the presence of an odorant while the trigeminal pathway helps inform the organisms about the risk of health hazards and injury .Cognitive bias plays a role in odor responses . Odors trigger memories of previous experiences and are influenced by the power of suggestion. If given a prior warning that an odor is harmful, increased irritation was reported. Fewer symptoms were reported if told the odor was healthful. Even when no odor was administered, suggestion that there was a harmful odor led to symptoms. Prior experience with an odor introduces bias, too. Emotional baseline is also a factor . Sensitization to an odorant occurs when an acute exposure triggers subsequent, more-severe responses, often at lower concentrations . Desensitization can occur when chronic exposure to an odorant increases the concentration required to trigger a response. For example, workers who are habituated and desensitized to an odorant may be baffled by neighborhood complaints . Due to the availability of human data, other animal data were not considered in the hazard identification. Further, humans have a smaller area of nasal olfactory epithelium than rodents, which makes humans more vulnerable to loss, and respiration rates are quite different . Only one experimental study of a typical, complex environmental odor and health effects was found , which included both physical effects and mood . Out of the dozens of parameters evaluated, only headaches,eye irritation and nausea symptoms were elevated among those exposed for one hour as compared to controls . The epidemiology evidence, however, indicated the full range of adverse effects from odor exposure .

Such symptoms were self-reported, which means they may include bias. The distance from facility, an objective measure, contrarily did not predict the frequency of symptoms. Interestingly,ebb and flow the relationship between odor exposure and health symptoms appeared to be greatly influenced by odor hedonic tone, perhaps more so than odor intensity. The debate whether the purely odor-related symptoms are psychological or have an actual underlying physical cause is ongoing. In the same issue of Archives of Environmental Health in 1992, two opposing perspectives were presented. Shusterman concluded that the evidence of health effects was lacking beyond odors’ ability to inflict annoyance. In the editorial immediately after his article, Ziem and David off countered that odor, and chemical sensitivity in general, may well be based on underlying physiological responses, as was often found in the case of sick building syndrome. Both agreed that better ways to determine the impact of odors were needed, and well-controlled prospective case-control studies would be especially welcome. The psychological symptoms of odor exposure include tension, nervousness, anger, frustration, embarrassment, depression, fatigue, confusion, frustration, annoyance, and general stress . Odor frequency, odor intensity and feeling their concerns are not being heard all contribute to annoyance, which leads to stress. Health worries contribute as well. See Table 4.2.Changes in odor-induced frontal lobe activity has been linked to changes in mood, drowsiness, and alertness . Unfortunately, the studies of this connection were few and additional research in this area is needed. Odor-induced brain activity is complex, involving more than 30 different regions. Exposure to malodor led to inability to focus on a task . Other studies reviewed found, however, that odors have no effect on task performance, so they concluded that the impact of odors on task performance may be odorant-specific. Increased prevalence of gastrointestinal symptoms were observed as a function of proximity to a wastewater treatment plant in Poland . The symptoms were correlated with both odors and microbiological pollutants and could not be disentangled to single out odors as the primary agent. Similarly, the negative effects of traffic noise and odor on residents in Windsor, Ontario, Canada, had a strong covariance between these two parameters and could not be differentiated .Some odorants and some co-pollutants within odors are considered hazardous air pollutants because they cause other adverse effects beyond smell and irritation.

Air that contains odorants also is known to contain odorless co-pollutants such as particulate matter and endotoxins . There was a positive correlation between the presence of odors and the prevalence of self-reported health symptoms, such as headache and nausea, when communities near hazardous waste sites were compared . However, more serious health outcomes – cancers, mortality and birth defects – were not higher compared to the control sites .Dose-response relationships for odors aim to link the percentage of people experiencing adverse effects, such as odor annoyance and irritation, to the level of exposure. For toxic chemicals, adverse effects increase as exposure increases. Odors, however, can be more inconsistent. For example, hydrogen sulfide loses its characteristic “rotten egg” odor note as the concentration increases, leading to harmful levels going unnoticed .The major goal of both risk assessment and odor assessment is to verify that exposures are below the thresholds of concern . For conventional risk assessment, the thresholds are health-based, often extrapolated from animal studies, and typically incorporate large margins of safety due to crude extrapolations and uncertainties. For odor assessment, achieving odorless air is the goal, yet due to the “lack of severity” of the effect, the acceptable limit is often set well above the odor-detection threshold. Given the wide variability in human response to odor, this approach is perilous, but a point of departure is needed, nonetheless. The amount of dilution required to achieve odorless air delivers a crude point of departure but should acknowledge the large error and be presented with only one significant figure in the final results. Thresholds for odorants typically vary by several orders of magnitude, especially the ODTC50 . Further, reliable methods may not have been used, and results for odor detection and odor recognition are sometimes mixed up. Within a controlled setting, two approaches to sensory testing of dilutions by panelists are used. One is the Odor Profile Method , which uses sugar solutions for calibration, and the other uses odor disappearance upon sufficient dilution. Both rely on dilution equipment, typically a dynamic dilution olfactometer that delivers sampled air diluted with odorless air to a nose port where the dilution is smelled by the panelist. Concentrations are presented in ascending order to avoid desensitization and anticipation bias. Statistics are then used on the panelists’ results to determine the ODTC50 for the odorant or mixture tested. For a single odorant, OPM is used to assign an odor note and intensity to each dilution. The Weber-Fechner law is applied, meaning that the logarithm of the concentration is taken and then the intensity results are fit to a line through linear regression. Extrapolation to intensity score 1 yields the ODTC50 value. Each odorant can have a vastly different slope. For example, a 200-fold change in concentrations of 1-propanol and n-amyl buterate caused a 15-fold and 0.5- fold change in odor intensity, respectively . For mixtures , the ODTC50 can be determined by forced choice, typically “triangle,” methods using the same dynamic dilution equipment . While inhaling at the nose port, the panelist rotates between three choices and then selects which is the diluted sample. A point estimate is generated rather than a curve, and no odor description is gathered. ASTM Method E679-04 has been used to determine the ODTC50 values for a range of odorants . Such methods have been used in the drinking water industry to set ODTC50 values for methyl tertiary butyl ether and improvements to ASTM Method E679-04 have been suggested for drinking water . In Europe, under EN 13725, the final dataset typically only includes the data for the four or more panelists whose results are the most consistent with the overall panel’s geometric mean value. Also, panelists may be presented with 2 samples instead of 3.

The BART scores increased significantly with abstinence , whereas the IGT scores did not change during abstinence. Self-reported total and motor impulsivity decreased significantly with abstinence and the non-planning score tended to decrease . The following changes were observed when restricting our longitudinal analysis to only those 17 PSU with baseline and follow-up data: general intelligence, executive function, working memory , visuospatial skills , global cognition , and processing speed . The 19 PSU not studied longitudinally differed from our abstinent PSU restudied on lifetime years of cocaine use . PSU not restudied performed significantly worse at baseline than abstinent PSU on cognitive efficiency, processing speed, and visuospatial learning . Furthermore, they did not differ significantly on years of education, AMNART, tobacco use severity, and proportions of smokers or family members with problem drinking, or the proportion of individuals taking a prescribed psychoactive medication.In PSU, more lifetime years drinking correlated with worse performance on domains of cognitive efficiency, executive function, intelligence, processing speed, visuospatial skills, and global cognition . More cocaine consumed per month over lifetime correlated with worse performance on executive function and greater attentional impulsivity . More marijuana consumed per month over lifetime correlated with worse performance on fine motor skills and tended to correlate with higher BIS-11 motor impulsivity ; in addition, more marijuana use in the year preceding the study correlated with higher non-planning and total impulsivity. Earlier onset age of marijuana use correlated with higher non-planning impulsivity and worse visuospatial learning . Interestingly, more lifetime years of amphetamine use correlated with better performance on fine motor skills, executive function, visuospatial skills, and global cognition . Similar to the associations found in PSU, more lifetime years drinking in AUD correlated with worse performance on cognitive efficiency, visuospatial skills, cannabis grow equipment and global cognition , and worse performance on visuospatial memory correlated with greater monthly alcohol consumption averaged over the year preceding assessment and over lifetime . In addition, longer duration of alcohol use in AUD was related to worse auditory-verbal learning and memory .

Our primary aim was to compare neurocognitive functioning and inhibitory control in onemonth-abstinent PSU and AUD. Poly substance users at one month of abstinence showed decrements on a wide range of neurocognitive and inhibitory control measures compared to normed measures. The decrements in neurocognition ranged in magnitude from 0.2 to 1.4 standard deviation units below a zscore of zero, with deficits >1 standard deviation below the mean observed for visuospatial memory and visuospatial learning. In comparisons to AUD, PSU performed significantly worse on measures assessing auditory-verbal memory, and tended to perform worse on measures of auditory-verbal learning and general intelligence. Chronic cigarette smoking status did not significantly moderate cross-sectional neurocognitive group differences at baseline. In addition, PSU exhibited worse decision-making and higher self-reported impulsivity than AUD , signaling potentially greater risk of relapse for PSU than AUD . Being on a prescribed psychoactive medication related to higher self-reported impulsivity in PSU. For both PSU and AUD, more lifetime years drinking were associated with worse performance on global cognition, cognitive efficiency, general intelligence, and visuospatial skills. Within PSU only, greater substance use quantities related to worse performance on executive function and fine motor skills, as well as to higher self-reported impulsivity. Neurocognitive deficits in AUD have been described extensively. However, corresponding reports in PSU are rare and very few studies compared PSU to AUD during early abstinence on such a wide range of neurocognitive and inhibitory control measures as administered here . To our knowledge, no previous reports have specifically shown PSU to perform worse than AUD on domains of auditory-verbal learning and general intelligence at one month of abstinence. Our studies confirmed previous findings of worse auditory-verbal memory and inhibitory control in individuals with a comorbid alcohol and stimulant use disorder compared to those with an AUD, and findings of no differences between the groups on measures of cognitive efficiency .

Some of the cross-sectional neurocognitive and inhibitory control deficits described in this PSU cohort are associated with previously described morphometric abnormalities in primarily prefrontal brain regions of a subsample of this PSU cohort with neuroimaging data . Our neurocognitive findings also further complement studies in subsamples of this PSU cohort that exhibit prefrontal cortical deficits measured by magnetic resonance spectroscopy and cortical blood flow . Our secondary aim was to explore if PSU demonstrate improvements on neurocognitive functioning and inhibitory control measures between one and four months of abstinence from all substances except tobacco. Polysubstance users showed significant improvements on the majority of cognitive domains assessed here, particularly cognitive efficiency, executive function, working memory, self-reported impulsivity, but an unexpected increase in risk-taking behavior . By contrast, no significant changes were observed for learning and memory domains, which were also worst at baseline, resulting in deficits in visuospatial learning and visuospatial memory at four months of abstinence of more than 0.9 standard deviation units below a z-score of zero. There were also indications for significant time-by-smoking status interactions for visuospatial memory and fine motor skills, however these analyses have to be interpreted with caution and considered very preliminary, considering the small sample sizes of smoking and nonsmoking PSU at followup. Nevertheless, the demonstrations of cognitive recovery in abstinent PSU, and potential effects of smoking status on such recovery, are consistent with our observations of corresponding recovery in abstinent AUD . The 19 PSU not studied at follow-up differed significantly from abstinent PSU at baseline onseveral important variables: they had more years of cocaine use over lifetime, and performed worse on cognitive efficiency, processing speed, and visuospatial learning. As such, these differences should be tested as potential predictors of relapse in future larger studies. Several factors limit the generalizability of our findings. Our cross-sectional sample size was modest and therefore our longitudinal sample of abstinent PSU was small; as not uncommon in clinical samples, about half of our PSU cohort relapsed between baseline and follow-up, a rate comparable to what has been reported elsewhere . This made us focus our longitudinal results reporting on the main effects of time and to de-emphasize the reporting of time-by-smoking status interactions. Larger studies are needed to examine the potential effects of smoking status and gender on neurocognitive recovery during abstinence from substances. The study sample was drawn from treatment centers of the Veterans Affairs system in the San Francisco Bay Area and a community based healthcare provider,vertical grow system and the ethnic breakdown of the study groups was different.

Therefore, our sample may not be entirely representative of community-based substance use populations in general. Although preliminary, the within subject statistics are meaningful as they are more informative for assessing change over time than larger cross-sectional studies at various durations of abstinence. In addition, premorbid biological factors and other behavioral factors not assessed in this study may have influenced cross-sectional and longitudinal outcome measures. Nonetheless, our study is important and of clinical relevance in that it describes deficits in neurocognition and inhibitory control of detoxified PSU that are different from those in AUD, and that appear to recover during abstinence from substances, potentially as a function of smoking status. Our cross-sectional and longitudinal findings are valuable for improving current substance use rehabilitation programs. The higher impulsivity and reduced cognitive abilities of PSU compared to AUD, likely the result of long-term comorbid substance use, and the lack of improvements in learning and memory during abstinence indicate a potentially reduced ability of PSU to acquire new cognitive skills necessary for remediating maladaptive behavioral patterns that impede successful recovery. As such, PSU may require a post-detox treatment approach that accounts for these specific deficits relative to AUD. Our results show that PSU able to maintain abstinence for 4 months had less total lifetime years of cocaine use and performed better on cognitive efficiency, processing speed and visuospatial learning than those PSU not restudied ; these variables may therefore be valuable for predicting future abstinence or relapse in PSU. Additionally, and if confirmed in larger studies, our preliminary results on differential neurocognitive change in smoking and nonsmoking PSU may inform a treatment design that addresses the specific needs of these subgroups within this largely understudied population of substance users. Potentially, concurrent treatment of cigarette smoking in treatment-seeking PSU may also help improve long-term substance use outcomes, just as recently proposed for treatment seeking individuals with AUD.

Finally, our findings on neurocognitive improvement in PSU imply that cognitive deficits are to some extent a consequence of long-term substance use , which have the potential for remediation with abstinence. This information is of clinical relevance and of psychoeducational value for treatment providers and treatment-seeking PSU alike. Patients with obstructive sleep apnea experience apneic and hypopneic events that, when untreated, have detrimental cardiovascular and neurocognitive consequences. Under normal conditions, blood pressure and heart rate decrease during non–rapid eye movement sleep and increase commensurately upon waking. This is attributed to a decrease in sympathetic nervous system activation and a subsequent increase in cardiac vagal tone during sleep . The transient episodes of hypoxemia and hypercapnia caused by apneas or hypopneas, as well as arousals, result in an increase in cardiac output and heart rate that leads to sympathetically induced peripheral vasoconstriction that causes a marked increase in blood pressure. The result of this chronic sympathetic excitation and inflammation does not resolve upon waking, and over time, together with the loss of the normal nocturnal blood pressure dip, it can lead to pathophysiologic changes such as impaired vascular function and stiffness . This impairment in the untreated patient with moderate to severe OSA has been found to increase the risk of both acute coronary syndrome and sudden cardiac death . The increased sympathetic nervous activity, inflammation, and oxidative stress seen in OSA can lead to hypertension. The prevalence of hypertension in moderate to severe OSA ranges between 13% and 60%, and OSA is considered the most common cause of secondary hypertension . Arrhythmias can be common in patients with OSA, and the prevalence of atrial fibrillation is higher in these patients than in patients without OSA. In fact, severe sleep disordered breathing is associated with twofold to fourfold higher odds of having complex arrhythmias. In addition, untreated OSA has been associated with higher rates of failure to maintain sinus rhythm after cardio version or ablation therapy . Inflammation, atrial fibrillation, and atherosclerosis are all associated with OSA and overlap with risk factors for cerebrovascular disease. OSA may be frequently diagnosed after stroke, and it can be difficult to determine whether the condition is causal or resultant. Evidence suggests that OSA is associated with an increased risk of stroke in elderly patients, and untreated OSA after stroke increases mortality risk during 10-year follow-up . Another disease state affected by sleep apnea is heart failure. Both OSA and central sleep apnea are common in patients with acute and chronic systolic and diastolic heart failure.However, screening for sleep disordered breathing can be difficult because patients with OSA and heart failure often do not report excessive daytime sleepiness. This absent symptom raises challenges in diagnosis and treatment adherence for OSA . Untreated OSA can affect many cognitive domains, including learning, memory, attention, and executive functioning. Data suggest that OSA is linked with cognitive impairment and may advance cognitive decline or dementia . In addition, intermittent hypoxemia and sleep fragmentation have been linked to structural changes in the brain that may be responsible for cognitive impairment . Given the increased prevalence of obesity and the common nature of diagnoses such as hypertension, coronary artery disease, atrial fibrillation, heart failure, and neurocognitive impairment, healthcare providers should be cognizant of the hazards of untreated OSA .Substance use, misuse, and dependence contribute immensely to the global burden of disease. Their harms extend far beyond their corrosive effects on health, safety, and well being and additionally include those associated with healthcare expenditures, productivity losses, criminal justice involvement, and other negative effects on social welfare. The incidence and harms of substance use, misuse, and dependence involve multilevel explanatory factors.

DSI can be blocked by postsynaptic Ca2 buffers or initiated by activity restricted to the postsynaptic side, and likely involves the opening of voltage-gated Ca2 channels , or release from intracellular stores. Changes in postsynaptic GABAA receptor sensitivity have been excluded, since the response to iontophoretically applied GABA did not change, and DSI had no effect on the amplitude of miniature IPSCs. Despite the clearly postsynaptic site of initiation, numerous experiments demonstrated that DSI is expressed presynaptically, i.e., as a reduction in GABA release. With the use of minimal stimulation, DSI was found to increase failure rate, multi-quantal components were also eliminated, and components of IPSCs were differentially influenced . In the cerebellum, axonal branch point conduction failure was shown to play a role . Furthermore, DSI was reduced by 4-aminopyridine and veratridine, both acting on the presynaptic terminal . Direct evidence for an inhibitory G protein-mediated presynaptic action has been provided by Pitler and Alger , as they showed that DSI was pertussis toxin sensitive. Both laboratories hypothesized from the very beginning that they were dealing with a phenomenon that involves retrograde messengers. Llano et al. stated that “Ca2 rise in the Purkinje cell leads to the production of a lipid-soluble second messenger.” This was a remarkable prediction 10 years before the discovery that, indeed, the lipid-soluble endocannabinoids are these messengers,cannabis grow system although the earlier claim of a retrograde action of arachidonic acid in the presynaptic control of LTP made this assumption rather plausible at that time.

The quest for identifying the chemical nature of this retrograde messenger began with the discovery of DSI. The slow onset , the requirement of a lasting Ca2 rise, and the Ca2 buffer effects were all consistent with a hormone or peptide rather than classical vesicular neurotransmitter. Yet the first substance suggested by direct experimental evidence was glutamate. In the cerebellum, metabotropic glutamate receptor agonists, acting on presynaptic group II mGluRs, were shown to mimic and occlude DSI, whereas antagonists reduced it . Activation of adenylate cyclase by forskolin reduced DSI, which is consistent with the proposed reduction of cAMP levels by mGluR2/3 activation that is known to lead to a reduction of GABA release . In contrast, in the hippocampus, forskolin and group II or III mGluR ligands were without effect on DSI; however, group I agonists occluded, and antagonists reduced it . Pharmacology and the anatomical distribution of the receptors suggested that mGluR5 is likely to be involved in the reduction of GABA release , but it appeared to be confined to the somadendritic compartment of the neurons perisynaptically around glutamatergic contacts , which was difficult to reconcile with the hypothesis of glutamate being the retrograde signal molecule . The long duration of DSI is not due to the dynamics of the Ca2 transient, as it was the same in EGTA and BAPTA , but probably to the slow disappearance of the retrograde messenger molecule from the site of action around the presynaptic terminal. This again is inconsistent with glutamate being the messenger , since this transmitter is known to be rapidly taken up. The fast buffer BAPTA and the slow buffer EGTA reduced DSI to a similar degree, suggesting that the site of Ca2 entry and the site of calcium’s action in DSI induction are relatively far from each other . One possibility is that the target of incoming Ca2 may be an intracellular Ca2 store that is able to produce large Ca2 transients required for the release of the signal molecule. On the other hand, the selective N-type Ca2 channel blocker -conotoxin was able to block DSI , which, according to recent evidence , turned out to be an action on the presynaptic terminals that are sensitive to DSI and selectively express the N-type Ca2 channel.

These data suggest that Ca2 plays a dual role: it is involved in the initiation phase via Ca2 -induced Ca2 release from intracellular stores in the postsynaptic side as well as in the effector phase via N-type Ca2 channels on presynaptic terminals . Obviously, DSI-like phenomena can have a functional role in neuronal signaling only if they can be induced by physiologically occurring activity patterns. In cerebellar Purkinje cells, 100-ms depolarization was required for a detectable reduction in IPSCs , which, under physiological conditions, may correspond to a few climbing fiber-induced complex spikes . Thus a short train of climbing fiber-induced spikes is expected to lead to an increased excitability of the innervated Purkinje cell for tens of seconds. Initiation by very few spikes, occasionally even two if closely spaced, has been reported in the hippocampus. With 100 M BAPTA in the pipette, detectable DSI could be evoked already by depolarization as short as 25 ms, and half-maximal effect was produced by 187 ms, or by 109-ms depolarization in the absence of BAPTA . This suggests a lower threshold, but also a smaller magnitude and shorter time course of DSI compared with the cerebellum. The behavior-dependent electrical activity patterns in the hippocampus that may lead to DSI are discussed in section VD.Recent studies by Kreitzer and Regehr provided evidence that, at least in the cerebellum, excitatory synaptic transmission is also under the control of retrogradely acting signal molecules. Both parallel fiber and climbing fiber-evoked EPSCs were suppressed for tens of seconds by a 50- to 1,000-ms depolarization of the postsynaptic Purkinje cells from 60 to 0 mV. Due to the obvious similarity to DSI, this phenomenon has been termed depolarization-induced suppression of excitation . Paired-pulse experiments, showing that short term plasticity is affected by the depolarization paradigm for both parallel and climbing fiber responses, demonstrated that the site of expression of DSE is presynaptic and involves a reduction in the probability of transmitter release. BAPTA in the recording pipette completely abolishes DSE,cannabis grow lights providing evidence for the requirement of postsynaptic Ca2 rise to trigger the event.Earlier reports are consistent with the lack of DSE in the hippocampus, but a recent study using excessive depolarization for 5–10 s argues for its existence also in this brain region.

Whether the mechanisms of DSE are similar in the hippocampus and cerebellum is discussed in the following section.The discovery by Wilson and Nicoll , OhnoShosaku et al. , and Kreitzer and Regehr that DSI/DSE are mediated by endocannabinoids revealed that investigations in both the cannabinoid and DSI/DSE fields have been dealing accidentally with the same subject, i.e., the mechanism of retrograde synaptic signaling via endocannabinoids. Both receptor localization data and identification of the physiological actions of cannabinoids on synaptic transmission confirmed that cannabinoids act on presynaptic axons, reducing transmitter release , whereas endocannabinoids are most likely released from the postsynaptic neuron upon strong stimuli that give rise to large Ca2 transients. Thus the signal molecules, which turned out to be endocannabinoids, travel from the post- to the presynaptic site and thus enable neurons to influence the strength of their own synaptic inputs in an activity-dependent manner. This may be considered as a short definition of retrograde synaptic signaling and perhaps, at the same time, summarizes the function of the endocannabinoid system. However, before trying to correlate the findings of cannabinoid and DSI studies, one should be aware of the major limitations. There are numerous examples of mismatch in receptor/transmitter distribution in the brain; receptors can be found in locations where they hardly ever see their endogenous ligand. Nevertheless, these receptors readily participate in mediating the effects of its exogenous ligands, e.g., during pharmacotherapy. We are facing the same problems with the relative distribution of cannabinoid receptors versus endocannabinoid release sites both at the cellular and subcellular levels. In addition, the distance to which anandamide and 2-AG are able to diffuse is also an important question from the point of identifying the degree of mismatch. Thus correlation of the sites of action of cannabinoid drugs and the sites of expression of DSI should reveal the regional, cellular, and subcellular domains where receptor and endogenous ligand distributions match, i.e., where endocannabinoids are likely to have a functional role in synaptic signaling. Several lines of evidence have been provided that endocannabinoids represent the retrograde signal molecules that mediate DSI both in the hippocampus and cerebellum, as well as DSE in the cerebellum. Antagonists of CB1 receptors fully block and agonists occlude DSI and DSE, whereas DSI is absent in CB1 receptor knock-out animals . In these experiments either single cell or paired recording has been used, and retrograde synaptic signaling has been evoked by the same procedures as described in the original work of Alger’s and Marty’s groups . In addition, Wilson and Nicoll demonstrated that uncaging of Ca2 from a photolabile chelator induces DSI that was indistinguishable from that evoked by depolarization. Thus a large intracellular Ca2 rise is a necessary and sufficient element in the induction of the release of endocannabinoids. As expected from the membrane-permeant endocannabinoids, their release does not require vesicle fusion, since botulinum toxin delivered via the intracellular recording pipette did not affect DSI.

A further crucial question concerns the range to which the released endocannabinoids are able to diffuse. Recordings at room temperature from pyramidal cells at various distances from the depolarized neuron releasing the signal molecules revealed that it is only the adjacent cell, at a maximum distance of 20 m, to which endocannabinoids are able to diffuse in a sufficient concentration to evoke detectable DSI . However, a considerably greater endocannabinoid uptake and metabolism should be expected at physiological temperatures, which likely results in a decreased spread and a more focused action. Earlier data indicating the involvement of glutamate and mGluR receptors in DSI also needed clarification . Varma et al. demonstrated that enhancement of DSI by mGluR agonists could be blocked by antagonists of both group I mGluR and CB1 receptors, whereas the same mGluR agonists were without effect in CB1 receptor knock-out animals. This provides direct evidence that any mGluR effects on DSI published earlier were mediated by endocannabinoid signaling, and glutamate served here as a trigger for the release of endocannabinoids rather than as a retrograde signal molecule as thought earlier. These data were subsequently confirmed by paired recordings from cultured hippocampal neurons . In a recent paper, Maejima et al. demonstrated that mGluR1 activation induces DSE in Purkinje cells even without changing the intracellular Ca2 concentration. This suggests that, at least in the case of cerebellar Purkinje cells, two independent mechanisms may trigger endocannabinoid synthesis ; one involves a transient elevation of intracellular [Ca2], and the other is independent of intracellular [Ca2] and involves mGluR1 signaling. This may imply that, under normal physiological conditions, different induction mechanisms may evoke the release of different endocannabinoids. With the growing number of potential endocannabinoids , the question arises whether they are involved in distinct functions, i.e., by acting at different receptors and/or at specific types of synapses. This question represents one of the hot spots of current endocannabinoid research, and direct measurements of the different endocannabinoid compounds during retrograde signaling should provide an answer. They may induce branch-point failure, decrease action potential invasion of axon terminals, reduce Ca2 influx into the synaptic varicosities via N- or P/Q-type channels, or block the release machinery somewhere downstream from the Ca2 signal. Using Ca2 imaging of single climbing fibers provided evidence that DSE involves a reduction of presynaptic Ca2 influx, which has the same time course as the reduction of the EPSC. Branch-point failure was shown not to contribute to DSE, at least in the case of climbing fibers, as stimulation of the examined single axon evoked a uniform rise of Ca2 throughout its entire arbor. These findings are supported by the fact that cannabinoids are known to block N-type Ca2 channels in neuroblastoma cells and reduce synaptic transmission by inhibiting both N- and P/Q-type channels in neurons . Inhibition of the release machinery is unlikely to play a role, particularly in GABAergic transmission, since CB1 receptor activation has little if any effect on mIPSC frequency in the presence of tetrodotoxin and cadmium . Furthermore, CB1 receptors tend to be localized away from the release sites, having a high density even on preterminal axon segments, which also argues against this possibility . In the hippocampus, evidence has been provided that DSI likely involves a direct action of G proteins on voltage-dependent calcium channels.

This clear morphological finding is also supported by work with CB_x0005_ /_x0005_ mice, which suggests that an additional receptor, pharmacologically related, but molecularly distinct from the CB1, may mediate the cannabinoid modulation of glutamatergic transmission in the hippocampus . We will return to this hypothesis in section IVB1B.CB1 receptors are also present in several subcortical nuclei of the basal forebrain. Cells expressing moderate levels of this receptor are located mainly in the teniatecta, the lateral and medial septum, and the nuclei of the vertical and horizontal limbs of the diagonal band . Colocalization experiments show that CB1 receptors may be present in somatostatin-positive neurons of the lateral septum and in cholinergic cells in the medial septum and the nucleus basalis of Meynert .In keeping with the profound impact of cannabimimetic drugs on motor activity , in situ hybridization studies have invariably reported strong expression of CB1 mRNA in the striatum . Detailed analysis at the regional and cellular level uncovered a selective expression pattern in specific components of basal ganglia networks . In rodents, the highest density of CB1 mRNA is found in the dorsolateral portion of the striatum, where the transcript is primarily localized to GABAergic medium spiny cells, which constitute  90% of striatal neurons. In contrast, CB1 mRNA expression is rather low in two key output structures of the basal ganglia in the globus pallidus and in the substantia nigra. This is also true for the human basal ganglia, which lack however the dorsoventral gradient of mRNA expression seen in rodents . Although the globus pallidus and the substantia nigra pars reticulata contain little CB1 mRNA,cannabis plant growing cannabinoid binding is remarkably dense in these structures, implying that CB1 receptors may be mainly localized to the axons of striatonigral and striatopallidal GABAergic neurons .

Indeed, two colocalization studies have now established that CB1 mRNA is expressed by neurons that also contain high levels of the enzyme GAD65 and low levels of its higher molecular mass isoform, GAD67 . In a separate study, CB1 mRNA was found to be coexpressed with both preproenkephalin and prodynorphin , indicating that striatal projection neurons express CB1 receptors irrespectively of their specific target region . Interestingly, a small fraction of CB1-positive neurons contain neither preproenkephalin nor prodynorphin and express high levels of GAD67, which is typical of striatal interneurons. Thus, in addition to medium spiny projection cells, other neurons also may express CB1 mRNA. Because colocalization experiments revealed that CB1 is found neither in somatostatin-positive nor in cholinergic interneurons , the presumptive candidates are the remaining parvalbumin-containing cells . Indeed, Marsicano and Lutz demonstrated that 15% of the CB1-expressing neurons are positive for parvalbumin, providing direct evidence that striatal local-circuit neurons express CB1 receptors. It is important to reiterate that this expression pattern is opposite to the one found in cortical and amygdaloid structures, where parvalbumin-positive interneurons do not express CB1 receptors . While the above results are based on the presence of CB1 mRNA in striatal projection neurons and local-circuit cells, the cellular expression pattern has not been confirmed yet at the protein level, although the presence of the CB1 protein in striatal neurons has already been demonstrated by immunostaining .In situ hybridization studies have reported very low levels of CB1 mRNA expression in the thalamus . Subsequent work confirmed this finding both at the mRNA and at the protein level and extended it to the human brain . Neurons expressing moderate amounts of CB1 mRNA were observed in the habenula and the anterior dorsal part of thalamus, while CB1-immunoreactive cells were found in the reticular nucleus and zona incerta . Further studies are needed, however, to unambiguously identify these cells and solve remaining inconsistencies in the literature regarding their exact location in different nuclei. This need is further underscored by the finding that anterior and dorsal nuclei of the thalamus may express high levels of monoacylglycerol lipase, an intracellular serine hydrolase implicated in terminating the biological effects of the endocannabinoid, 2-AG .There is a coherent body of evidence indicating that the endocannabinoid system participates in the hypothalamic regulation of feeding and neuroendocrine function . Likewise, anatomical investigations agree in finding moderate levels of CB1 receptor expression in the ventromedial and anterior nuclei of the hypothalamus , while pharmacological experiments suggest that these receptors may be particularly well coupled to G proteins .

Importantly, a double-labeling study showed that CB1 receptors are colocalized with calretinin, a marker for glutamatergic neurons in select hypothalamic nuclei , but not with GAD65 . This suggests that glutamatergic, but not GABAergic, cells may express CB1 receptors in these nuclei. Other hypothalamic nuclei display very low levels of CB1 expression in a population of uniformly distributed cells. These nuclei include the medial and lateral preoptic nucleus, the magnocellular preoptic and hypothalamic nucleus, the premammilary nucleus and the lateral nucleus of the mammilary body, and the lateral hypothalamus . However, as elsewhere in the brain, there is still disagreement as to the precise identity and localization of hypothalamic CB1-expressing neurons, which will undoubtedly foster further scrutiny.The finding that noxious stimuli trigger anandamide release in the PAG, as assessed by in vivo microdialysis , implies that this midbrain structure may serve as a relay in the pain-processing circuit modulated by the endocannabinoids. Yet, a coherent description of the regional and cellular expression of CB1 receptors in the midbrain is still lacking. Although current data suggest that several midbrain nuclei may have very low to moderate expression of CB1 mRNA, they are in conflict regarding the exact identity of these nuclei . Immunostaining studies have shown that the superior colliculus contains CB1-positive neuronal cell bodies, but the identity of these cells was not determined . To be able to interpret the growing body of work on the analgesic and antihyperalgesic effects of cannabinoid agents, these morphological gaps need to be filled.Detailed morphological studies of the hindbrain are also rare. A notable exception is represented by the recent immunocy to chemical demonstration of CB1 receptors in the dorsal vagal complex of the ferret, which may be relevant to the autonomic and antiemetic effects of cannabinoid agonists . The exclusive presence of these receptors in local GABAergic interneurons, but not in preganglionic motor neurons , shows how this intriguing morphological leitmotif may recurrently be found at most levels of the neuraxis.CB1 receptor mRNA is highly abundant in the cerebellum . Owing to the well-determined circuitry of the cerebellar cortex, along with its laminar structure, the identification of neuronal elements expressing CB1 receptors in this region is relatively straightforward.

Strong expression levels are found in glutamatergic granule cells, but not in the GABAergic Purkinje cells . In the molecular layer, several large cells were also reported to express CB1,vertical grow rack which might belong to the basket and stellate cells . However, it is not known whether all cerebellar interneurons express CB1 or a subtype selectivity exists among them.One of the most important aspects of cannabinoids in terms of medicinal usefulness is their analgesic and antihyperalgesic effect at multiple stages of the pain-processing pathway, from high cognitive centers of the forebrain to the midbrain and down to peripheral tissues . The spinal cord, where cells expressing CB1 receptors have been extensively characterized, is obviously an integral component of this circuit. Most in situ hybridization and immuno staining studies agree that CB1 receptors are present in select neuronal populations of the spinal dorsal horn . In lamina II, GABAergic neurons expressing CB1 also contain nitric oxide synthase , a marker for a subset of spinal interneurons called islet cells . In addition, CB1- positive cells have also been found in lamina X, which surrounds the central canal of the spinal cord ; however, by using a different antibody, these cells could only be visualized after spinal transection.Primary sensory neurons in these ganglia are classified based on the selective expression of various neuropeptides [calcitonin gene-related peptide , substance P, somatostatin], or the responsiveness to neurotrophic factors [nerve growth factor , glial-derived growth factor , present in nociceptive neurons]. These cell-specific markers are rather heterogeneously colocalized with CB1 receptors. In a small population of dorsal root ganglion cells, CB1 receptors are present in CGRP and substance P-expressing neurons, but not in somatostatin-positive cells . This suggests that CB1 receptors may be expressed only by a subset of peptidergic nociceptive neurons, which represent 25% of all CB1- positive cells, whereas the remaining CB1-expressing cells may belong to other sub-populations of nociceptive or nonnociceptive neurons. Work in dorsal root ganglion cultures suggests that CB1 receptors colocalize with another nociceptor marker, the acid- and heat-sensitive vanilloid receptor 1 . Further triple immuno labeling experiments confirmed this observation and suggested that 25% of CB1-bearing neurons are nonnociceptive and that distinct types of nociceptive neurons express the receptor as well .

This highly heterogeneous distribution may contribute to explain the unprecedented analgesic effectiveness of cannabinoid agents, particularly in animal models of persistent pain of neuropathic origin .Based on the selective distribution of CB1 receptors in the CNS and their pervasive association with GABAergic interneurons, one would predict that the endocannabinoid system may play important and, possibly, unique roles in the local control of neuronal network activity. A growing body of functional evidence supports this prediction. For example, microdialysis experiments have found that anandamide is released in the striatum by activation of dopamine D2 receptor, where it may act as a short range mediator to counterbalance dopamine activity . Furthermore, an endocannabinoid substance, which remains unfortunately uncharacterized, has been recently identified as a key component in two related forms of trans-synaptic communication, known as depolarization induced suppression of inhibition and depolarization-induced suppression of excitation . In section V, we discuss how the endocannabinoid system may participate in these processes. But to do that, we first need to take a further step in the localization of CB1 receptors, down to the sub-cellular level. G protein-coupled receptors, such as the CB1, are embedded within the lipid bilayer of the plasma membrane. The membrane surface of a nerve cell can be subdivided into two functionally distinct spatial domains. The dendritic tree and cell body are equipped to receive synaptic contacts at specialized structures called active zones, where receptors for fast-acting neurotransmitters such as glutamate or GABA are concentrated. G protein coupled receptors are rarely associated with these structures; rather, a significant proportion of these receptors are found outside the synapse, within the so-called perisynaptic zone or even further away on the dendritic tree , where they can influence synaptic currents and neuronal excitability by triggering the formation of diffusible intracellular second messengers. Another group of G protein-coupled receptors is situated on axon terminals, where they are exquisitely poised to regulate the release of neurotransmitters, thereby controlling the final output of a neuron. Thus the question arises, in which neuronal surface domain are CB1 receptors localized? The most direct way to approach this question consists, when a receptor-specific antibody is available, in analyzing the sub-cellular distribution of the receptor by using electron microscopy. This approach can also provide a wealth of information on the structure and function of the synapse, such as the complement of neurotransmitters and additional membrane receptors present. Evidence from anatomical studies such as these, as well as functional experiments, indicates that CB1 receptors are predominantly found in axon terminal membranes, where they may be involved in the presynaptic regulation of neurotransmitter release.Indirect anatomical evidence for the localization of CB1 receptors on axon terminals was first provided by in situ hybridization and receptor binding experiments . These studies showed that, in the basal ganglia, CB1 receptor mRNA is almost exclusively localized to neurons within the striatum , whereas cannabinoid binding is strongest in the globus pallidus and the substantia nigra pars reticulata . This mismatch implies that CB1 receptors synthesized in the cell bodies of striatal projection neurons are transported to axon terminal fields in the pallidum and substantia nigra. In keeping with this hypothesis, ibotenic acid lesion of the rat striatum produces a marked loss of cannabinoid binding in these two regions .

First, motivated by the potential therapeutic applications of cannabis-like molecules, laboratories in academia and the pharmaceutical industry began to develop families of synthetic analogs of delta-9-THC. These agents exerted pharmacological effects that were qualitatively similar to those of delta-9- THC but displayed both greater potency and stereoselectivity. The latter feature cannot be reconciled with nonspecific membrane interactions, providing the first evidence that delta-9-THC exerts its effects by combining with a selective receptor. Second, as a result of these synthetic efforts, it became possible to explore directly the existence of cannabinoid receptors by using standard radioligand binding techniques. In 1988, Howlett and her co-workers described the presence of high-affinity binding sites for cannabinoid agents in brain membranes and showed that these sites are coupled to inhibition of adenylyl cyclase activity. Conclusively supporting these findings, in 1990 Matsuda et al. serendipitously came across a complementary DNA encoding for the first G protein-coupled cannabinoid receptor, now known as CB1. In heterologous expression systems, CB1 receptors were found to be functionally coupled to multiple intracellular signaling pathways, including inhibition of adenylyl cyclase activity,cannabis growing inhibition of voltage-activated calcium channels, and activation of potassium channels . In situ hybridization and immunohistochemical studies have demonstrated that CB1 receptors are abundantly expressed in discrete regions and cell types of the central nervous system but are also present at significant densities in a variety of peripheral organs and tissues .

The selective distribution of CB1 receptors in the CNS provides a clear anatomical correlate for the cognitive, affective, and motor effects of cannabimimetic drugs. The cloning and characterization of CB1 receptors left several important problems unsolved. Since antiquity, it has been known that the actions of Cannabis and delta-9-THC are not restricted to the CNS, but include effects on nonneural tissues such as reduction of inflammation, lowering of intraocular pressure associated with glaucoma, and relief of muscle spasms. Are these peripheral effects all produced by activation of CB1 receptors? An initial answer to this question was provided by the discovery of a second cannabinoid receptor exquisitely expressed in cells of immune origin . This receptor, called CB2, only shares 44% sequence identity with its brain counterpart, implying that the two sub-types diverged long ago in evolution. The intracellular coupling of the CB2 receptor resembles, however, that of the CB1 receptor; for example, in transfected cells, CB2 receptor activation is linked to the inhibition of adenylyl cyclase activity . The experience with opioid receptors and the enkephalins has accustomed scientists to the idea that whenever a receptor is present in the body, endogenous factor that activate this receptor also exist. Not surprisingly, therefore, as soon as cannabinoid receptors were described, a search began to identify their naturally occurring ligand. One way to tackle this problem was based on the premise that, like other neurotransmitters and neuromodulators, an endogenous cannabinoid substance should be released from brain tissue in a calcium dependent manner. Taking this route, Howlett and coworkers incubated rat brain slices in the presence of a calcium ionophore and determined whether the media from these incubations contained a factor that displaced the binding of labeled CP-55940, a cannabinoid agonist, to brain membranes. These studies demonstrated that a cannabinoid-like activity was indeed released from stimulated slices, but the minute amounts of this factor did not allow the elucidation of its chemical structure .

Devane, Mechoulam, and co-workers , at the Hebrew University in Jerusalem, adopted a different strategy. Reasoning that endogenous cannabinoids may be as hydrophobic as delta-9-THC, they subjected porcine brains to organic solvent extraction and fractionated the lipid extract by chromatographic techniques while measuring cannabinoid binding activity. This approach turned out to be highly successful, and the researchers were able to isolate a lipid cannabinoid-like component, which they characterized by mass spectrometry and nuclear magnetic resonance spectroscopy as the ethanolamide of arachidonic acid. They named this novel compound “anandamide” after the sanskrit “ananda,” inner bliss. The chemical synthesis of anandamide confirmed this structural identification and allowed the characterization of its pharmacological properties . In vitro and in vivo tests showed a great similarity of actions between anandamide and cannabinoid drugs. Anandamide reduced the electrogenic contraction of mouse vas deferens and closely mimicked the behavioral responses produced by delta-9-THC in vivo; in the rat, the compound was found to produce analgesia, hypothermia, and hypomotility. However, these effects may not be exclusively due to cannabinoid receptor activation, as anandamide is readily metabolized to arachidonic acid, which can be converted in turn to a variety of biologically active eicosanoid compounds. Subsequent studies demonstrated that anandamide is released from brain neurons in an activity-dependent manner and elucidated the unique biochemical routes of anandamide formation and inactivation in the CNS . Thus anandamide fulfills all key criteria that define an endogenous cannabinoid substance. In their 1992 study, Devane, Mechoulam, and coworkers reported that several lipid fractions from the rat brain contained cannabinoid-binding activity, in addition to anandamide’s. In characterizing these fractions, they discovered that some of them were composed of polyunsaturated fatty acid ethanolamides similar to anandamide , but others were instead constituted of a distinct lipid component, sn-2-arachidonoyl-glycerol . Sugiura et al. arrived independently to the same conclusion.

That polyunsaturated fatty acid ethanolamides should mimic anandamide, to which they are structurally very similar, does not come as a great surprise. Moreover, the pharmacological properties of these fatty acid ethanolamides, essentially indistinguishable from those of anandamide, and their scarcity in brain relegate them, at least for the moment, to a position secondary to anandamide’s. We cannot say the same for 2-AG. This lipid, considered until now a mere intermediate in glycerophospholipid turnover , is present in the brain at concentrations that are 170-fold greater than those of anandamide and possesses two pharmacological properties that make it crucially different from the latter: it binds to both CB1 and CB2 cannabinoid receptors with similar affinities, and it activates CB1 receptors as a full agonist, whereas anandamide acts as a partial agonist.We have learned much over the past 10 years on the behavioral effects of these molecules, on how these lipid mediators are produced physiologically, and on the functional roles that they may serve. A major step was the discovery that depolarization-induced suppression of inhibition , a type of short-term synaptic plasticity originally discovered in the cerebellum and the hippocampus ,cannabis grow equipment is mediated by endocannabinoids . This discovery allowed the results of over a decade of research on retrograde synaptic signaling in these networks to be considered as functional characteristics of endocannabinoid signaling. The substrate of retrograde signaling and DSI is the predominantly presynaptic distribution of CB1 receptors on axon terminals in the hippocampus , as well as throughout the brain, where activation of CB1 by endocannabinoids can efficiently veto neurotransmitter release in many distinct types of synapses . The conditions of synthesis, release, distance of diffusion, duration of effect, and site of action were all extensively characterized for the mediator of DSI that turned out to be an endocannabinoid . The fact that neurons are able to control the efficacy of their own synaptic input in an activity-dependent manner is functionally very important, since this mechanism may sub-serve several functions in information processing by neuronal networks from temporal coding and oscillations to group selection and the fine tuning of signal-to-noise ratio.

The crucial involvement of endocannabinoids in these functions just began to emerge from recent studies, which are reviewed in section V. Due to the exceptionally rapid expansion of this field in recent years , we decided to focus the present review on questions related to the composition of the endocannabinoid system and its physiological roles in controlling brain activity at the regional and cellular levels as synaptic signal molecules. We did not aim to provide detailed accounts of studies dealing with other, similarly important, aspects of cannabinoid research, which have been dealt with in excellent recent reviews, e.g., about the relation of the endocannabinoid system to pain modulation , the immune system , neuroprotection , and addiction . The final message of the present review is that to understand the possible physiological functions of the endogenous cannabinoids, their roles in normal and pathological brain activity, pharmacological agents targeting the cascade of anandamide and 2-AG formation, release, uptake, and degradation will have to be developed. Such drugs, which undoubtedly will become invaluable research tools to study the potential functions listed above, may also provide novel therapeutic approaches to diseases whose clinical, biochemical, and pharmacological features suggest a link with the endogenous cannabinoid system.A basic principle that has emerged from the last two decades of research on cellular signaling is that simple phospholipids such as phosphatidylcholine or phosphatidylinositol should be regarded not only as structural components of the cell membrane, but also as precursors for transmembrane signaling molecules. Intracellular second messengers like 1,2-diacylglycerol and ceramide are familiar examples of this concept. Along with their intracellular roles, however, lipid compounds may also serve important functions in the exchange of information between cells. Indeed, biochemical mechanisms analogous to those involved in the generation of DAG or ceramide give rise to biologically active lipids that leave their cell of origin to activate G protein-coupled receptors located on the surface of neighboring cells. Traditionally overshadowed by amino acid, amine, and peptide transmitters, biologically active lipids are now emerging as essential mediators of cell-to-cell communication within the CNS, where G protein-coupled receptors for multiple families of such compounds, including lysophosphatidic acid and eicosanoids, have been identified . In this section, we discuss the biochemical properties of endogenous lipids that activate brain cannabinoid receptors. These compounds share two common structural motifs: a polyunsaturated fatty acid moiety and a polar head group consisting of ethanolamine or glycerol . Because of these features, endocannabinoid substances seemingly resemble the eicosanoids, ubiquitous bio-active lipids generated through the enzymatic oxygenation of arachidonic acid. However, the endocannabinoids are clearly distinguished from the eicosanoids by their different bio-synthetic routes, which do not involve oxidative metabolism. The two best characterized endocannabinoids, anandamide and 2-AG , may be produced instead through cleavage of phospholipid precursors present in the membranes of neurons, glia, and other cells. In the following sections, we will first focus on the biochemical pathways that lead to the formation of endocannabinoids in neurons and then turn to the mechanism by which these compounds are deactivated.Anandamide formation via energy-independent condensation of arachidonic acid and ethanolamine was described in brain tissue homogenates soon after the discovery of anandamide and was attributed to an enzymatic activity that was termed “anandamide synthase” . Subsequent work has demonstrated, however, that this reaction is in fact catalyzed by fatty acid amide hydrolase , the primary enzyme of anandamide hydrolysis, acting in reverse . Since FAAH requires high concentrations of arachidonate and ethanolamine to synthesize anandamide, higher than those normally found in cells, this enzyme is unlikely to play a role in the physiological formation of anandamide . Another model for anandamide biosynthesis is illustrated schematically in Figure 2. According to this model, anandamide may be produced via hydrolysis of the phospholipid precursor N-arachidonoyl phosphatidylethanolamine , catalyzed by a phospholipase D -type activity . The precursor consumed in this reaction may be resynthesized by a separate enzyme activity, N-acyltransferase , which may transfer an arachidonate group from the sn-1 glycerol ester position of phospholipids to the primary amino group of PE . The validity of this model was initially questioned, because previous studies had failed to detect N-arachidonoyl PE in mammalian tissues . More recent chromatographic and mass spectrometric analyses have unambiguously shown, however, that N-arachidonyl PE is present in brain and other tissues, where it may serve as a physiological precursor for anandamide . Although biochemically distinct, anandamide formation and N-arachidonoyl PE synthesis are thought to proceed in parallel. Both reactions may be initiated by intracellular Ca2 rises and/or by activation of neurotransmitter receptors . For example, administration of dopamine D2-receptor agonists to rats in vivo causes a profound stimulation of anandamide release in the striatum , which is likely mediated by de novo anandamide synthesis . Unfortunately, the two key enzyme activities responsible for these reactions, PLD and NAT, have only been partially characterized, and their molecular properties are still unknown .

Chronic inflammation and immune activation potentially predispose PLWH to greater risk for premature and accentuated aging, making prevention and treatment of comorbidities an important component of HIV-related care . Specifically, the three most common comorbidities for PLWH are hypertension, hyperlipidemia, and endocrine disease , which are all components of metabolic syndrome . MetS is conceptualized as a constellation of interrelated metabolic risk factors associated with an increased risk of developing cardiovascular disease : Expert Panel on Detection and Treatment of High Blood Cholesterol in Adults 2002. MetS is defined differently by various organizations, but generally includes visceral obesity, hypertension, endothelial dysfunction, atherogenic dyslipidemia, and insulin resistance . MetS is common in the USA, with approximately 34–35% of adults aged 18 years or older in the general population falling within the clinical criteria, and greater prevalence of MetS is observed with increasing age . Furthermore, MetS has also been consistently linked to neurocognitive dysfunction and brain abnormalities . Among PLWH, MetS is highly prevalent and there is evidence that its impact on neurocognitive impairment might be even more notable among PLWH than in the general population , possibly because of the impact of MetS on blood–brain barrier integrity and systemic inflammation . Aside from MetS, neurocognitive impairment is prevalent in HIV, occurring in approximately 40% of PLWH . HIV infiltrates the central nervous system early in the course of disease, resulting in neurocognitive impairment, which is often mild to moderate in severity in the era of combination ART. Another manifestation of CNS dysfunction in HIV are neurobehavioral disturbances or changes in daily behavior indicative of problems with motivation, initiating and organizing behavioral responses,cannabis drainage system and regulating emotional and behavioral responses in appropriate contexts .

These neurobehavioral disturbances have been empirically linked to frontal-subcortical dysregulation and central nervous system disease and may be present in the absence of neurocognitive impairment . Previous research has shown a consistent link between HIV serostatus and increased neurobehavioral disturbances, particularly increased apathy , disinhibition , and executive dysfunction . However, no studies have investigated the role of MetS on neurobehavioral disturbances associated with HIV. The main purpose of the present study was to examine the association between MetS and neurobehavioral disturbances in the context of HIV disease. Given prior findings by Yu et al. , we hypothesized that there would be an interaction between HIV serostatus and MetS on neurobehavioral disturbances, such that the association between MetS and neurobehavioral disturbances would be stronger among PLWH than among a HIV-uninfected comparison group, even after controlling for significant demographic and psychiatric characteristics and neurocognitive impairment.Participants included 215 adults enrolled in the baseline visit of the MultiDimensional Successful Aging among HIV-Infected Adults study conducted at the University of California San Diego HIV Neurobehavioral Research Program and the UCSD Sam and Rose Stein Institute for Research on Aging from 2013 to 2015 . Inclusion criteria included being between the ages of 36–65 years old, being fluent in English, and having the ability to provide informed consent. Exclusion criteria included the presence of a neurologic condition other than HIV known to impact cognitive functioning , diagnosis of a psychotic condition that could impact neurocognitive test performance , and having a positive urine toxicology screen on day of testing for an illicit substance other than cannabis.In order to be included in present analyses, participants had to have data available on the main variables of interest, i.e., MetS and neurobehavioral disturbances.

The UCSD Institutional Review Board approved the study, and all participants provided written informed consent and were compensated for participating. Participants self-reported demographic characteristics and completed a comprehensive neuropsychiatric and neuromedical evaluation in individual sessions conducted by trained study staff.Neurobehavioral disturbances were assessed via the 46-item self-report version of the Frontal Systems Behavior Scale . Participants provide retrospective ratings of how often they experience specific neurobehavioral symptoms “before the illness or injury” and “at the present time” using a Likert-type scale ranging from 1 to 5 . The scale yields T-scores adjusted for demographics for the entire scale and three sub-scales measuring apathy, disinhibition, and executive dysfunction. T-scores have a mean of 50 and a standard deviation of 10, and higher T-scores indicate greater reports of neurobehavioral disturbances, with a Tscore of 65 and higher suggesting clinical neurobehavioral disturbance. Previous studies have reported good internal reliability and consistent factor structure of the FrSBe sub-scales . Consistent with previous research present time FrSBe T-scores were used as the outcome of interest for the current study.All statistical analyses were conducted using SPSS 24 and JMP 11.0.0 and considered statistically significant at p < .05. Descriptive statistics were computed for FrsBe scores, MetS, demographic and psychiatric characteristics, neurocognitive impairment, and HIV disease characteristics. Group comparisons by HIV serostatus on demographic and psychiatric characteristics and neurocognitive impairment were conducted . HIV serostatus and MetS group differences on FrsBe scores were also conducted via independent sample t tests. In order to examine the potential interactive effect of HIV and MetS on neurobehavioral disturbances, we conducted a series of linear regression models with terms for HIV serostatus, MetS, and their interaction on each FrSBe subscale. In cases where the interaction term was not significant,it was removed from the model. The independent and unique effect of HIV serostatus and MetS on each FrSBe subscale was then assessed by evaluating linear regression models that included terms for HIV serostatus, MetS,indoor cannabis grow system and relevant covariates. In order to adjust for relevant covariates while also obtaining a parsimonious model for each FrSBe subscale, we followed these steps: identified sociodemographic and psychiatric variables in Table 1 that were associated with each FrSBe subscale at p < .10 via a series of univariate regression models; entered variables identified in Step 1 of the linear regression models and applied a stepwise backwards selection method based on Akaike information criterion to obtain a parsimonious model for each FrSBe subscale.

Age, sex, and education were not considered as possible covariates as FrSBe T-scores are adjusted for those demographic factors.MetS disproportionally impacts neurocognitive impairment, a marker of central nervous system dysfunction, among PLHIV compared to HIV-uninfected persons . Present findings revealed that similar interactive effects of HIV serostatus and MetS were not observed in the present sample on other behavioral manifestations associated with central nervous system dysfunction, i.e., neurobehavioral disturbances . Instead, there was an additive effect such that being HIV seropositive and having a clinical identification of MetS were independently associated with greater apathy and executive dysfunction, and there was a significant effect of HIV serostatus only on disinhibition. The presence of greater difficulties with neurobehavioral disturbances in PLWH compared to the HIV-uninfected comparison group aligns with previous research . When looking at the frontal subcortical circuits that may be affected, neuroimaging research has documented links between damage to the anterior cingulate cortex, dorsolateral prefrontal cortex, and orbital frontal cortex with difficulties with apathy, executive dysfunction, and disinhibition, respectively . Further, HIV-associated structural changes in both gray and white matter corresponding to these same areas have been documented . These cross-sectional findings inform the hypothesis that neurobehavioral disturbances seen in PLWH are associated with disease-related volume reduction and over-activation in comparison to HIV-uninfected comparison participants. These findings are of great interest not only from understanding how HIV affects the brain but also everyday functioning. For example, previous studies have shown associations between apathy and IADL decline, disability, and quality of life ; disinhibition, impulsivity, and risk-taking behaviors ; and executive dysfunction and ART medication adherence and employment status in PLWH. Further research is needed to understand association directionality and how these associations progress with age over time. While MetS and the related risk factors have been shown to be an important and unique predictor of neurocognitive change and decline in the general population , little is known on how MetS is related to neurobehavioral disturbances. Previous research has shown that the presence of MetS is associated with increased odds of presenting with higher white matter hyperintensity volumes and characterized by an anterior-posterior pattern of deterioration, such that greater deterioration is observed in the frontal lobe structures . Although not fully understood, several possible hypotheses on the mechanisms underlying the association between MetS and central nervous system dysfunction have been proposed, such as neuroinflammation, oxidative stress, abnormal brain lipid metabolism, altered cerebral hemodynamics, regional hypoperfusion, impaired cerebrovascular reactivity, and small vessel disease . While the current findings are based on self-report, greater difficulties with apathy and executive dysfunction parallels the known associations between MetS and brain structure and function. Specifically, executive function, typically measured by neuropsychology test performance, appears to be particularly sensitive to the neurologic impact of MetS .

Examination of individual components of MetS indicates that insulin resistance , diabetes mellitus , obesity , and hypertension have been linked to impaired performance on executive function tasks. Interestingly, HIV serostatus and MetS were independently associated with increased neurobehavioral disturbances within the same model, but there was no evidence of a statistical interaction. This is somewhat inconsistent with findings from Yu et al. who found evidence of an interaction on neurocognitive performance, such that association between MetS and neurocognitive impairment was stronger among PLWH than an HIV-uninfected comparison group. Yu et al. included a similar sample to ours, indicating that differences in participants’ characteristics are unlikely to explain differential findings across studies. At least part of the reason for the apparent inconsistency might be that while neurocognitive impairment and neurobehavioral disturbances are both indicative of underlying central nervous system dysfunction, there is evidence that they can exist in isolation from one another . Neurobehavioral disturbances are usually associated with dysfunction to frontal-subcortical circuitry, while our index of global neurocognitive deficits includes various neurocognitive domains which are mediated by a variety of brain structures. Furthermore, prior findings indicate that the impact of MetS on neurocognition among PLWH is most notable in the domains of learning and motor functioning, with smaller effects on executive function . Additionally, differences in HIV and MetS findings with neurobehavioral disturbances could allude to differential impacts on frontal-subcortical circuitry as there are both shared and segregated components to their structure that can only be better investigated and understood using neuroimaging and longitudinal design.Given the high prevalence of MetS and related negative health outcomes, efforts to prevent, treat, and possibly reverse the effects of MetS in middle-aged and older adults is of the greatest public health interest .Additionally, increasing daily physical exercise and reducing physical inactivity in combination with a healthy diet has also shown to be effective in reducing metabolic risk and reversing MetS components . These lifestyle modifications may be particularly important for PLWH as previous research has shown varying levels of sedentary leisure time and physical inactivity . For example, Moore et al. showed using ecological momentary assessment in a sample of middle-aged PLWH that 32% of their time was spent engaging in passive leisure activity compared to only 5% of their time which was spent engaging in physical exercise. Given the links between neurocognition and physical activity in PLWH , more research is needed to see if interventions designed to increase physical activity for an example and improve diet may further reverse MetS components as well as the related-cognitive consequences.While we have discussed findings primarily in the direction of HIV and MetS impacting neurobehavioral disturbances, it is important to consider that the directionality of the findings cannot be ascertained in the context of the present cross-sectional analyses. It might be the case that pre-existing neurobehavioral disturbances resulted in persons being more likely to acquire HIV and/or MetS. Additionally, given the strong association between certain ART regimens and lipid and glucose metabolism in PLWH and the high prevalence of these drug class types in our sample, further longitudinal investigation of lifetime and current ART regimens may provide more detail on the associations between HIV, MetS, and neurobehavioral disturbances. Another limitation included that neurobehavioral disturbances were based on self-report rather than informant report, observation, or performance-based tasks. While self-report might provide insight into daily behavior that may not be adequately captured or assessed with laboratory or clinic testing, self-report may also be confounded with bias, lack of awareness, and stigma of disease.

Vaping is a term relating to heating a liquid and inhaling the “vapor” produced. Vaping first became popular as a means of inhaling tobacco without combusting it. Electronic cigarettes consisting of a battery, heating coil, and liquid reservoir usually containing nicotine were developed and went through several “generations” of modification. The third generation consists normally of a vape pen, holder containing the battery and heating oil, and a liquid cartridge with or without nicotine. The liquid consists of glycerin and ethylene glycol typically in amounts of 30–70%. A third liquid is also included at about 1/3 of the total amount. Some terpenes for taste and odor and nicotine may also be included. The vaper heats the cartridge for a few seconds , inhales the aerosol and exhales it into the room or ambient air. Many studies of secondhand exposure to e-cigarette aerosol have been published.Recently, vaporization of marijuana has emerged as a popular method of delivering marijuana. This method heats marijuana liquid to the point of vaporization, avoiding combustion.Shortly after this method was introduced, Earley wine and Van Dam reported on four subjects who smoked marijuana and agreed to switch to vaping for a short period. All four refused to return to smoking marijuana at the end of the experiment. Eight years later, these early adopters of vaping have been joined by millions of persons worldwide. For example, 3.8%, 10.5%, and 13.8% of about 25 million US high school students reported vaping marijuana in 2016, 2017, and 2018, respectively . Abrams et al. showed that vaping marijuana produced similar levels of THC in blood as smoking marijuana cigarettes,hydro tray without the increase in carbon monoxide in exhaled breath associated with combustion.

Essentially all passive exposure to marijuana smoke from vaping is from exhaled breath since there is no side stream smoke. The aerosol emerging from exhaled breath will be different in many respects from the inhaled aerosol, due to lung deposition, humidification, growth, and coagulation, so it is important to test exposure under real-world conditions using human vapers. One recent study has focused on indoor air concentrations of particles due to various indoor sources, including both marijuana and tobacco smokers . This study included 193 persons, of whom about 22% and 15% smoked tobacco and marijuana, respectively. It may be the first study to look at passive exposure to marijuana from human smokers in their own homes. The authors found that nonsmokers exposed to persons smoking either tobacco or marijuana cigarettes had roughly twice the exposure to fine particles as non-exposed nonsmokers. The Dylos monitors used in this study were not calibrated by comparison to gravimetric levels, so the investigators could not estimate PM2.5 exposures or source strengths. Exposure models depend on the vaping “topography” including frequency of use, depth or time of inhalation, and time retained in the lungs. McClure et al. studied 20 heavy users who were allowed to smoke marijuana cigarettes freely over 4 days. On average, they smoked 12 cigarettes per 9-h day, taking 13 puffs from each cigarette. The volume per puff ranged from 51 to 61 ml. A second study of 98 Dutch adolescents found that they smoked an average of 2.5 joints per day of use, and 21 days of use per month . Another required parameter in an exposure model is the air exchange rate. Chan et al. used leakage information to show that rates in the US vary in log-normal fashion from about 0.1 to 2 h-1. The rate is affected by the indoor-outdoor temperature difference and by wind direction and speed .

One of the strongest effects on air exchange rates is window-opening behavior . The volume of the home is another necessary parameter, statistics for which can be obtained for the US from the US Census Bureau . Although these previous studies are useful in developing exposure models, we believe that no studies have sufficiently characterized the two crucial ingredients of such models: source strengths and decay rates of real-world aerosols from vaping marijuana liquids by human subjects. In this study, we use more than 100 controlled experiments involving human vapers in rooms within inhabited homes to provide information on source strengths and decay rates, from which models of exposure can be built. The main objective of the study was to measure, under real-world conditions, the two main parameters affecting secondhand PM2.5 exposure to marijuana aerosol from vaping: the source strength and removal rate from the air. The source strength is the mass of PM2.5 emitted and is generalizable to other locations and situations. The removal rate for nonvolatile particles not subject to coagulation is the deposition rate k . In the case of vaping marijuana, the deposition rate may be augmented by evaporation, so the removal rate = k + evaporation rate . In carrying out this objective, we evaluated the calibration factors for the 3 p.m. instruments measuring vaping aerosol. For the Side Pak and Piezo balance monitors, the CFs were determined directly using gravimetric techniques . Since the Purple Air monitors in this study were collocated with the Side Pak monitors, the CF for them was determined by direct comparison with the Side Pak readings. A secondary objective was to compare the performance of a low-cost monitor to research-grade instruments . If the low-cost monitor performed sufficiently well, it could be adopted in future studies of exposure. It offers the opportunity of a much broader sample of homes and participants. It is able to monitor continuously with no maintenance. In the case of Purple Air, there is also an existing network on the internet that can be sampled at will by a researcher.

Three main particle monitor types were used in the study: an optical monitor with a PM2.5 impactor ; a monitor employing a piezoelectric crystal , also with a PM2.5 impactor; and a low-cost optical monitor providing estimates of PM1, PM2.5 and PM10 . The Piezobalance is manufactured by Kanomax, Inc. Japan, and has previously been licensed for sale in the US by TSI Inc., Shoreview, MN. Piezobalances used in this study included models from both Kanomax USA Inc. , and TSI, Model 8510. For the Piezobalances used in this study, a special connector has been added by the factory, which allows the 1-min average frequency counts to be output to a computer where they can be logged. The instrument employs a vibrating quartz crystal exposed to a steady flow rate that has passed through a PM2.5 impactor. As the exposed crystal collects particles, its frequency changes due to the piezoelectric principle,planting table and within a certain frequency range the change in frequency is proportional to the amount of material collected on the exposed crystal. The frequency change during each measured time interval is then multiplied by the factory-set calibration factor to give an estimate of the amount of mass collected during the time interval. The SidePak is an optical particle monitor. It uses a laser to sense particles as they pass through a chamber. The scattered light is collected and calculated as a volume determined by applying Mie scattering formulae. The SidePak is calibrated at the factory using ISO 12103-1 Test Dust . As with all optical monitors, it is recommended that the particular aerosol mixture being studied be analyzed using gravimetric methods, so that a calibration factor can be determined for that aerosol. For example, the calibration factor for the SidePak has been found to be about 0.32 for tobacco smoke . We have been able to determine a calibration factor for the marijuana aerosol produced by vaping . The PurpleAir instruments use a laser of ~650 nm wavelength to sort particles into one of six size categories . There are two lasers in each monitor, providing the opportunity to detect departures from normal operation and calculate internal precision. The monitors have a small inaudible fan to counter “starvation” of air at the face of the monitor. They operate off line current and have no battery. Every 80 s they upload observations directly to the Web.

The monitors provide the number per deciliter of particles in each of the six categories. Also, they provide two data series, identified as CF1 and CF ATM for PM1, PM2.5, and PM10. The manufacturer of the sensor is a Chinese company . The company does not provide details on the calibration aerosol used, such as the density, or any correction factors employed in calculating PM1, PM2.5 or PM10. Therefore, we chose not to use the CF1 or CF ATM data series provided by Plan tower. Instead we adopted a standard method for determining PM2.5 from the particle numbers provided for the three size categories up to 2.5 μm. We chose an intermediate particle diameter within each category to represent all particles in the category, calculated the resulting particle volume, and determined a reference mass by adopting a density of 1 g cm-3. This approach succeeded in improving the limit of detection from about 2 μg/m3 using the CF1 or ATM to ~1 μg/m3 . The calibration factors for the Piezobalance and SidePak response to vaping marijuana were studied using gravimetric procedures by Zhao et al. . The Piezobalance CF was 0.97 . The SidePak CF was 0.44 . A carbon monoxide monitor was employed to estimate the air exchange rate of each of the two experimental rooms. A known amount of carbon monoxide was released using a flow rate regulator attached to a 107-liter cylinder containing 10% CO . The air exchange rate was determined as the negative slope of the background-corrected logarithm of the CO concentration. A correction was made for the temperature based on observations of the variation of the Langan monitor readings with temperature. Tests were carried out between May 21, 2018 and May 25, 2019. Each test was conducted in a room in a home. Two rooms were used, one in Santa Rosa and one in Redwood City . Rooms were sealed off from the remainder of the home. The HVAC system was off and floor registers sealed. Usually no fan was employed. In some experiments, one or two table fans were employed to test the effect of a fan on measured decay rates. Two Piezobalances, two PurpleAir monitors, and 2–3 SidePaks were employed for each experiment. They were situated at two well-separated locations at heights between 0.9 and 1 m. A single Langan electrochemical device was set at a central location in the room to monitor CO. CO was released using the cylinder discussed above. A target peak concentration above 5 ppm was set. Background PM2.5 concentrations were collected for 5–10 min before the experimenter took one or more puffs of the heated marijuana oil. A battery operated device was used to vaporize marijuana oil from a 500 ml cartridge . Oils with different CBD/THC ratios were tested: 18:1 ; 8:1 ; 7:1 ; and 2:1 . The amount of CBD and THC was listed for each cartridge. For example, the 8:1 CBD/THC ratio included 336 mg CBD and 40 mg THC. The missing 124 ml liquid was not identified. The other formulations also included about 2/3 marijuana liquid and 1/3 unidentified liquid. Only one person at each location was the vaper. He sat or stood at a location roughly equidistant from the two locations for the instruments. After completing the protocol for heating the cartridge , the experimenter left the room. Two protocols for heating the cartridges were adopted to study the effect of different heating times on the amount of vapor produced. Protocol I consisted of heating the oil for 3 s by pressing the power button on the vaping pen and then inhaling for three additional seconds while still pressing the power button. Protocol II involved heating for 12 s before the 3-s inhale, a total of 15 s of heating compared to 6 s in Protocol I. Source strengths were calculated as follows. Since the initial peaks registered by the monitors occurred under conditions of poorly-mixed air, the true estimated peak concentration assuming perfect mixing was determined by calculating decay rates after good mixing was attained . The line of best fit could then be extended “backward” in time to the time of the puff.