Medication and supplement pharmacokinetic changes following bariatric surgery: A systematic review and meta-analysis

OBJECTIVES

To evaluate the impact of bariatric surgery on the pharmacokinetic (PK) parameters of orally administered medications and supplements.

METHODS

Systematic searches of bibliographic databases were conducted to identify studies. Pooled effect estimates from different surgical procedures were calculated using a random-effects model.

RESULTS

Quantitative data were synthesized from 58 studies including a total of 1985 participants. Whilst 40 medications and 6 supplements were evaluated across these studies, heterogeneity and missing information reduced the scope of the meta-analysis to the following medications and supplements: atorvastatin, paracetamol, omeprazole, midazolam, vitamin D, calcium, zinc, and iron supplements. There were no significant differences in PK parameters post-surgery for the drugs atorvastatin and omeprazole, and supplements calcium, ferritin, and zinc supplements. Paracetamol showed reduced clearance (mean difference [MD] = -15.56 L/hr, p = 0.0002, I2 = 67%), increased maximal concentration (MD = 6.90 μg/ml, p = 0.006, I2 = 92%) and increased terminal elimination half-life (MD = 0.49 hr, p < 0.0001, I2 = 3%) post-surgery. The remaining 36 medications and 2 supplements were included in a systematic review. Overall, 18 of the 53 drugs and supplements showed post-operative changes in PK parameters.

CONCLUSION

This study demonstrates heterogeneity in practice and could not reach conclusive findings for most PK parameters. Prospective studies are needed to inform best practice and enhance patient healthcare and safety following bariatric surgery.

Broad evidence of xylazine in the UK illicit drug market beyond heroin supplies: Triangulating from toxicology, drug-testing and law enforcement

BACKGROUND AND AIMS

Xylazine is a non-opioid sedative which has spread rapidly throughout the US illicit drug supply. This study aimed to describe the spread of xylazine throughout the UK illicit drug supply.

METHODS

Xylazine detections in human biological samples were collated from toxicology laboratories operating in the United Kingdom with the date, location, case type, xylazine concentration and co-detected drugs (with quantifications where performed) detailed, where permitted, by the corresponding coroner. Drug-testing cases positive for xylazine were collated from the Welsh Emerging Drugs and Identification of Novel Substances (WEDINOS) drug-testing postal service with the date, location, purchase intent and co-detected drugs detailed. Drug seizures made by UK law enforcement were communicated by the Office for Health Improvement and Disparities with the date and location detailed.

RESULTS

By the end of August 2023, xylazine was detected in 35 cases from throughout toxicology, drug-testing and drug seizure sources covering England, Scotland and Wales. There were no cases reported from Northern Ireland. Xylazine was detected in biological samples from 16 people. In most cases where full toxicology results were provided, xylazine was detected with heroin and/or a strong opioid (n = nine of 11), but this polydrug use pattern was not evident in all cases (n = two of 11), suggesting a wider circulation of xylazine in the UK illicit drug market beyond heroin supplies. Evidence from WEDINOS supports this claim, as all 14 drug samples (100%) submitted from across the UK contained xylazine; however, in none of these cases was heroin the purchase intent but rather counterfeit prescription medication tablets (n = 11 of 14), tetrahydrocannabinol (THC) vapes (n = two of 14) or white powder (n = one of 14). Additional evidence for the spread of illicit xylazine comes from five drug seizures made by law enforcement.

CONCLUSIONS

Xylazine has penetrated the UK illicit drug market and is not limited to heroin supplies.

An evaluation of naloxone transit for opioid overdose using drones: A case study using real-world coroner data

BACKGROUND AND AIMS

Opioids are now the most cited class in fatal overdoses. However, the antidote for opioid overdose-naloxone-is not always readily available. Our aim was to evaluate the feasibility of naloxone transit via drone to provide rapid access at the point of care.

METHODS AND FINDINGS

Real-world data pertaining to opioid overdoses, which occurred in the Teesside area of the UK 2015-2019, were extracted from the National Programme on Substance Abuse Deaths (NPSAD). The original locations of these opioid overdoses were used to compare the projected response times of ambulances with that of drones when considering the impacts of actual traffic and weather conditions, respectively; 58 cases were identified where a bystander-who could have called for and administered emergency naloxone-was likely present.

RESULTS

In 78% of cases (n = 45/58) a class C1 commercial-off-the-shelf drone carrying naloxone could have reached the overdose location in 7 min-the benchmark time for the arrival of emergency services for Category 1 calls in England. With the implementation of recent advances in drone engineering, such as increased speeds and temperature-controlled cargo cradles, it is estimated that 98% of overdoses could have been reached in this timeframe (n = 57/58). Ambulances were able to reach a significantly lower number of cases in 7 min, even when considering best-case scenario traffic conditions (14%, n = 8/58, χ2 P < 0.001).

CONCLUSIONS

This study provides proof-of-concept that, in the Teesside area of the UK, drones are more likely than ambulance to get naloxone to the site of an opioid overdose in 7 min.

New synthetic cannabinoids and the potential for cardiac arrhythmia risk

Synthetic cannabinoid receptor agonists (SCRAs) have been associated with QT interval prolongation. Limited preclinical information on SCRA effects on cardiac electrogenesis results from the rapid emergence of new compounds and restricted research availability. We used two machine-learning-based tools to evaluate seven novel SCRAs' interaction potential with the hERG potassium channel, an important drug antitarget. Five SCRAs were predicted to have the ability to block the hERG channel by both prediction tools; ADB-FUBIATA was predicted to be a strong hERG blocker. ADB-5Br-INACA and ADB-4en-PINACA showed varied predictions. These findings highlight potentially proarrhythmic hERG block by novel SCRAs, necessitating detailed safety evaluations.

Trends in deaths following drug use in England before, during, and after the COVID-19 lockdowns

Aim

This research aimed to describe how the characteristics of deaths following drug use changed during the COVID-19 pandemic in England, and how this can inform future strategy to support the health and social care of people who use drugs in future emergency scenarios.

Method

All deaths reported to the National Programme on Substance Abuse Deaths which occurred between January 2018 and December 2021 inclusive were extracted for analysis. Exponential smoothing models were constructed to determine any differences between forecasted vs. actual trends.

Key results

Following the first lockdown period in England there were significant increases in the proportion of people who died at home beyond the 95% confidence bounds of the exponential smoothing model and concurrent decreases in the proportion of people who died in hospital. Whilst the overall proportion of deaths attributable to opioids did not significantly deviate from the forecasted trend, there were significant increases in methadone-related deaths and decreases in heroin/morphine-related death beyond the 95% confidence bounds. The proportion of deaths concluded as suicide increased, as did those implicating antidepressant use. There were no changes in the proportion of deaths following use of other drug classes, alcohol use in combination with psychoactive drugs, or on decedent demographics (gender, age, and drug user status). A small number of deaths due to drug use had COVID-19 infection itself listed as a cause of death (n = 23).

Conclusion

For people who use drugs, the impact of the restrictions due to the COVID-19 pandemic was greater than that of infection from the virus itself. The health and social care strategy for these people needs to be pre-emptively adapted to mitigate against the specific risk factors for fatal drug overdose associated with future emergency scenarios.

The first drug-related death associated with xylazine use in the UK and Europe

BACKGROUND AND AIMS

On November 8th^, 2022, the United States Food and Drug Administration (FDA) issued a statement alerting healthcare professionals to the increasing prevalence of xylazine in illicit drug overdoses in the country. Xylazine is a veterinary medicine with sedative, analgesic and muscle relaxant properties that is used as a heroin/fentanyl adulterant on the illicit drug market in North America. Here we report the first drug-related death associated with xylazine in the United Kingdom.

METHODS

The National Programme on Substance Abuse Deaths (NPSAD) receives reports on drug-related deaths from coroners In England, Wales and Northern Ireland on a voluntary basis. The NPSAD was searched for cases with xylazine detections in cases received by December 31, 2022.

RESULTS

One drug-related death associated with xylazine use was reported to NPSAD by December 31, 2022. The deceased was a 43-year-old male who was found dead at home with drug paraphernalia located at the property in May 2022. The post-mortem examination identified recent puncture wounds to the groin. Coronial documentation reports that the deceased had a history of illicit drug use. A number of drugs were detected by post-mortem toxicology and xylazine was implicated in death alongside heroin, fentanyl and cocaine.

CONCLUSIONS

To the best of our knowledge, this is the first death associated with xylazine use reported in the UK, and even Europe, and indicates the entry of xylazine into the UK drug supply. This report highlights the importance of monitoring changes in illicit drug markets and the emergence of new drugs.

A Fatal Case Report of Barium Chloride Toxicity

Barium is an alkaline earth metal whose toxicity is dictated by its compounded salt form: barium sulfate is insoluble and safe to ingest, but other barium salts (chloride, carbonate, sulfide, oxide and acetate) are bioavailable and therefore toxic when ingested. There have been 49 previous reports of fatal intoxications following barium consumption: 38 deemed accidental in nature, 8 suicidal, 1 homicidal and 2 of undetermined intent. In this report, we detail the first intentional fatal self-poisoning with barium chloride to be reported in the UK, along with a review of the surrounding literature. This is the first case to report quantified levels of barium in blood and vitreous humor, and by providing details of sample collection, storage and processing, this case will aid in future interpretations.

A case-control study of antipsychotic use and pneumonia-related mortality in the United Kingdom

BACKGROUND AND AIM

There is increasing evidence linking antipsychotic use with pneumonia, but limited evidence of an effect on pneumonia-related outcomes such as mortality. In this study, we aimed to examine the association of pneumonia-related death with specific antipsychotic exposure.

METHOD

Deaths analysed were those reported to a UK-based drug-related deaths database, the National Programme on Substance Abuse Deaths (NPSAD), between 1997 and September 2020. We conducted a case-control study with cases defined as pneumonia-related deaths and controls as cases with alternative causes of death. Cases were analysed by considering drugs detected at post-mortem (PM) and by drugs prescribed to the deceased at the time of their death with calculated odds ratios (ORs) adjusted to account for confounders.

RESULTS

There were 2467 PM cases and 40,128 controls; 1818 prescribed cases and 28,018 controls. Second generation antipsychotics (SGAs) were robustly associated with an increased risk of pneumonia-related death compared with those not prescribed or taking antipsychotics (PM detection adjusted OR [AOR] 1·34 [95% CI 1·15-1·55]; prescribed AOR 1·28 [95% CI 1·11-1·49]). First generation antipsychotics had no clear association with death from pneumonia (PM detection AOR 1·06 [95% CI 0·77-1·47]; prescribed AOR 0·91 [95% CI 0·71-1·17]). Amongst SGAs, olanzapine was associated with an increased risk of death due to pneumonia (PM detection AOR 1·49 [95% CI 1·22-1·82]; prescribed AOR 1·44 [95% CI 1·18-1·76]) as was quetiapine (PM detection AOR 1·34 [95% CI 1·07-1·66]; prescribed AOR 1·28 [95% CI 1·01-1·64]).

CONCLUSION

Olanzapine and quetiapine were found to increase the risk of pneumonia-related death in this NPSAD sample to a clinically important extent.

Opioid-related deaths during hospital admissions or shortly after discharge in the United Kingdom: A thematic framework analysis of coroner reports

BACKGROUND

People who use heroin and other illicit opioids are at high risk of fatal overdose in the days after hospital discharge, but the reasons for this risk have not been studied.

METHODS

We used the National Programme on Substance Abuse Deaths, a database of coroner reports for deaths following psychoactive drug use in England, Wales, and Northern Ireland. We selected reports where the death occurred between 2010 and 2021, an opioid was detected in toxicology testing, the death was related to nonmedical opioid use, and death was either during an acute medical or psychiatric hospital admission or within 14 days after discharge. We used thematic framework analysis of factors that may contribute to the risk of death during hospital admission or after discharge.

RESULTS

We identified 121 coroners' reports; 42 where a patient died after using drugs during hospital admission, and 79 where death occurred shortly after discharge. The median age at death was 40 (IQR 34-46); 88 (73%) were male; and sedatives additional to opioids were detected at postmortem in 88 cases (73%), most commonly benzodiazepines. In thematic framework analysis, we categorised potential causes of fatal opioid overdose into three areas: (a) hospital policies and actions. Zero-tolerance policies mean that patients conceal drug use and use drugs in unsafe places such as locked bathrooms. Patients may be discharged to locations such as temporary hostels or the street while recovering. Some patients bring their own medicines or illicit opioids due to expectations of low-quality care, including undertreated withdrawal or pain; (b) high-risk use of sedatives. People may increase sedative use to manage symptoms of acute illness or a mental health crisis, and some may lose tolerance to opioids during a hospital admission; (c) declining health. Physical health and mobility problems posed barriers to post-discharge treatment for substance use, and some patients had sudden deteriorations in health that may have contributed to respiratory depression.

CONCLUSION

Hospital admissions are associated with acute health crises that increase the risk of fatal overdose for patients who use illicit opioids. Hospitals need guidance to help them care for this patient group, particularly in relation to withdrawal management, harm reduction interventions such as take-home naloxone, discharge planning including continuation of opioid agonist therapy during recovery, management of poly-sedative use, and access to palliative care.

Can cannabis kill? Characteristics of deaths following cannabis use in England (1998-2020)

BACKGROUND

Cannabis is the most widely used illegal drug but is rarely considered a causal factor in death.

AIMS

This study aimed to understand trends in deaths in England where cannabinoids were detected at post-mortem, and to evaluate the clinical utility of post-mortem cannabinoid concentrations in coronial investigations.

METHODS

Deaths with cannabinoid detections reported to the National Programme on Substance Abuse Deaths (NPSAD) were extracted and analysed.

RESULTS

From 1998 to 2011, on average 7% of all cases reported to NPSAD had a cannabinoid detected (n = 110 deaths per year), rising to 18% in 2020 (n = 350). Death following cannabis use alone was rare (4% of cases, n = 136/3455). Traumatic injury was the prevalent underlying cause in these cases (62%, n = 84/136), with cannabis toxicity cited in a single case. Polydrug use was evident in most cases (96%, n = 3319/3455), with acute drug toxicity the prevalent underlying cause (74%, n = 2458/3319). Cardiac complications were the most cited physiological underlying cause of death (4%, n = 144/3455). The median average Δ9-tetrahydrocannabinol post-mortem blood concentrations were several magnitudes lower than previously reported median blood concentrations in living users (cannabis alone: 4.3 µg/L; cannabis in combination with other drugs: 3.5 µg/L).

CONCLUSIONS

Risk of death due to cannabis toxicity is negligible. However, cannabis can prove fatal in circumstances with risk of traumatic physical injury, or in individuals with cardiac pathophysiologies. These indirect harms need careful consideration and further study to better elucidate the role cannabis plays in drug-related mortality. Furthermore, the relevance of cannabinoid quantifications in determining cause of death in coronial investigations is limited.

Synthetic Cannabinoid-Related Deaths in England, 2012-2019

Aim: To identify drug-related death trends associated with synthetic cannabinoid receptor agonists (SCRAs) reported to the National Programme on Substance Abuse Deaths (NPSAD) from England. Design: Case reports from NPSAD (England) where a SCRA was detected in post-mortem tissue(s) and/or implicated in the death were extracted, analyzed, and compared against non-SCRA-related deaths that occurred over the same time period (2012-2019). Findings: One hundred sixty-five death SCRA-related reports were extracted, with 18 different SCRAs detected. Following the first death in 2012, a subsequent sharp increase in reporting is evident. Acute SCRA use was the underlying cause of death in the majority of cases (75.8%) with cardiorespiratory complications the most frequently cited underlying physiological cause (13.4%). SCRA users were predominantly found dead (68.6%), with a large proportion of those witnessed becoming unresponsive described as suddenly collapsing (81.6%). Psychoactive polydrug use was detected in 90.3% of cases, with alcohol the most commonly co-detected (50.3%), followed by opioids (42.2%), benzodiazepines/Z-drugs (32.1%), stimulants (32.1%, [28.5% cocaine]), and cannabis (24.8%). Compared to all non-SCRA-related NPSAD deaths occurring over the same time period, SCRA-related decedents were more predominantly male (90.3% vs. 72.0%; p<0.01), and lived in more deprived areas (p<0.01). While a comparatively significant proportion of decedents were homeless (19.4% vs. 4.1%), living in a hostel (13.3% vs. 2.3%) or in prison (4.9% vs. 0.2%) at time of death (all p<0.01), the greatest majority of SCRA-related decedents were living in private residential accommodations (57.6%). Conclusions: This is the largest dataset regarding SCRA-related mortalities reported to date. Reporting of SCRA-related deaths in England have increased considerably, with polydrug use a specific concern. Lack of effective deterrents to SCRA use under current UK legislation, compounded by limited knowledge regarding the physiological impacts of SCRA consumption and their interaction with other co-administered substances are contributory factors to the occurrence of SCRA-related mortalities in an increasingly deprived demographic.

Adverse experiences resulting in emergency medical treatment seeking following the use of lysergic acid diethylamide (LSD)

BACKGROUND

Recreational lysergic acid diethylamide (LSD) use is growing in popularity amid increasing research interest on psychedelics and their possible therapeutic potential yet; the potent psychotropic effects of LSD may result in adverse reactions and behaviour.

AIMS

This study aimed to investigate the 12-month incidence and nature of LSD-related adverse experiences resulting in emergency medical treatment (EMT) seeking in an international sample of people reporting LSD use.

METHODS

We use data from the 2017 Global Drug Survey - a large anonymous online survey on patterns of drug use conducted between November 2016 and January 2017.

RESULTS

Out of 10,293 past-year LSD users, 102 (1.0%) reported seeking EMT, with a per-event risk estimate of 0.2%. Younger age, comorbid mental health conditions and higher frequency of use were associated with increased risk of EMT seeking. The most common symptoms were psychological, including anxiety, panic and confusion, with the most common explanatory factors cited by respondents being poor 'setting' and 'mindset'. Most responders reported feeling back to normal within 24 h, but 11 participants experienced persistent issues after 4 weeks.

CONCLUSION

The results suggest that LSD is a relatively safe drug in recreational settings. Adverse reactions are typically short-lived, self-limiting and psychological in nature. Sub-optimal set and setting were commonly reported as suspected contributory factors. Within clinical settings, patient screening, preparatory sessions and supervision should reduce these acute risks considerably.

Fatalities associated with gabapentinoids in England (2004-2020)

The gabapentinoids were reclassified as Schedule II medications and Class C drugs in the UK in 2019 due to their potential misuse. In this study we examined deaths following gabapentinoid use in England reported to the National Programme on Substance Abuse Deaths.

A total of 3051 deaths were reported (gabapentin: 913 cases; pregabalin: 2322 cases [both detected in 184 cases]). Prescribed and illicitly obtained gabapentinoids accounted for similar proportions of deaths (gabapentin illicit 38.0%, prescribed 37.1%; pregabalin illicit 41.0%, prescribed 34.6%). Opioids were co‐detected in most cases (92.0%), and co‐prescribed in a quarter (25.3%). Postmortem blood gabapentinoid concentrations were commonly (sub)therapeutic (65.0% of gabapentin cases; 50.8% of pregabalin cases). In only two cases was gabapentinoid toxicity alone attributed in causing death.

Gabapentinoids alone rarely cause death. Clinically relevant doses can, however, prove fatal, possibly by reducing tolerance to opioids. Doctors and patients should be aware of this interaction.

Gabapentinoid–opioid co‐prescribing needs urgent revision.

Highlighting the hidden dangers of a 'weak' opioid: Deaths following use of dihydrocodeine in England (2001-2020)

BACKGROUND

Dihydrocodeine (DHC) is considered a 'weak' opioid, but there is evidence of its increasing misuse in overdose deaths. This research aims to analyse trends in DHC-related deaths in England relevant to source and dose of DHC, and decedent demographics.

METHODS

Cases from England reported to the National Programme on Substance Abuse Deaths (NPSAD) where DHC was identified at post-mortem and/or implicated in death between 2001 and 2020 were extracted for analysis.

RESULTS

2071 DHC-related deaths were identified. The greatest number of deaths involved illicitly obtained DHC and a significant increase in these deaths was recorded over time (r = 0.5, p = 0.03). However, there was a concurrent decline in the implication rate of DHC in causing death (r = -0.6, p < 0.01). Fatalities were primarily due to accidental overdose (64.8%) and misuse was highly prevalent in combination with additional central nervous system depressants (95.3%), namely illicit heroin/morphine and diazepam. In contrast, when DHC was obtained over-the-counter (OTC) suicide mortality accounted for almost half of the deaths (42.5%). Differences in polysubstance use were also identified, with less heroin/morphine and benzodiazepine co-detection, but increased OTC codeine co-detection.

CONCLUSIONS

DHC misuse in England is increasing. The pharmacological consideration of DHC as a 'weak' opioid may be misinterpreted by users, leading to accidental overdosing. There is an urgent need to understand increasing polypharmacy in overdose deaths. Additionally, suicides involving DHC is a potential cause for concern and a review of OTC opioid-paracetamol preparations is necessary to determine whether the benefits of these medications continue to outweigh the risks of intentional overdose.

The First Fatal Intoxication with 3-MeO-PCP in the UK and a Review of the Literature

The phencyclidine derivative 3-Methoxyphencyclidine (3-MeO-PCP) is a potent dissociative hallucinogen. Sought for recreational use as a novel psychoactive substance, it can also induce acute psychological agitation and pathophysiological cardiorespiratory effects. Due to the harms associated with its use, 3-MeO-PCP was added to the 'Green List' of materials covered by the 1971 Convention on Psychotropic Substances as a Schedule II substance by the United Nations Commission on Narcotic Drugs in April 2021. There have been 15 previous reports of fatal intoxications following 3-MeO-PCP use, but only one was attributable to 3-MeO-PCP intoxication alone. In this report we detail the first fatality due to 3-MeO-PCP intoxication to be reported in the UK, along with a review of the surrounding literature. Whilst the blood concentrations associated with 3-MeO-PCP toxicity and fatality remain unclear, by providing details of sample collection and storage conditions this case will aid in future interpretations. Furthermore, this case suggests that 3-MeO-PCP toxicity may be exacerbated by exercise. Users of 3-MeO-PCP should be cautioned against its use as a 'club drug' or in a similar setting where elevations in heart rate, body temperature and blood pressure may occur.

Deaths from novel psychoactive substances in England, Wales and Northern Ireland: Evaluating the impact of the UK psychoactive substances act 2016

BACKGROUND

'Legal highs' began appearing in the UK in the mid-2000s. Whilst many of these substances were controlled under the 1971 Misuse of Drugs Act, novel compounds and new variants of controlled compounds were continuously being introduced to the recreational drug market. The Psychoactive Substances Act (PSA) was therefore implemented in 2016 as a blanket ban on all novel psychoactive substances (NPS).

AIM

To evaluate the impact of the PSA on deaths following NPS use in England, Wales and Northern Ireland.

METHODS

Cases reported to the National Programme on Substance Abuse Deaths where death had occurred 3 years pre- or post-implementation of the PSA were extracted. Cases with NPS detected at post-mortem were analysed and compared against cases non-NPS cases.

RESULTS

293 deaths with NPS detected were identified; 91 occurring before the PSA and 202 afterwards, indicating an 222.0% post-PSA increase. Contrastingly, non-NPS drug-related death case reporting increased by only 8.0%. Synthetic cannabinoid, anxiolytic/sedative and stimulant NPS were detected in the largest proportions of deaths pre-PSA; post-PSA stimulant NPS detections reduced whilst synthetic cannabinoid and anxiolytic/sedative detections increased.Post-PSA, average decedent age increased significantly (mean age pre-PSA 34.4 ± 10.8 vs post-PSA 38.3 ± 9.4), and they were significantly more likely to have been living in deprived areas (pre-PSA 50.0% vs post-PSA 65.9%).

CONCLUSIONS

Reporting of deaths following NPS use has risen despite introduction of the PSA. Whilst deaths amongst younger individuals and those living in more affluent areas has reduced, additional approaches to prohibition are needed to curb their persistence in deprived demographics.

Recreational ketamine-related deaths notified to the National Programme on Substance Abuse Deaths, England, 1997-2019

BACKGROUND

Ketamine is a phencyclidine derivative with dissociative anaesthetic properties. Increasing numbers of individuals in England take ketamine recreationally. Information on deaths arising from such use in England is presented.

METHODS

Cases were extracted on 31 January 2020 from the National Programme on Substance Abuse Deaths database, based on text searches of the cause of death, coroner's verdict and positive toxicology results for the terms 'ketamine' or 'norketamine'.

FINDINGS

During 1997-2005, there were <5 deaths p.a. in which ketamine was implicated. Numbers increased until 2009 (21), plateauing until 2016; thereafter, deaths have risen to about 30 p.a. Decedents' characteristics (N = 283): male 84.1%, mean age 31.2 (SD 10.0) years, employed 56.5%, drug use history 79.6% and living with others 60.3%. Ketamine was detected with other substances in most cases. Main (74.6%) underlying cause of death was accidental poisoning. Ketamine may have impaired judgement in other cases.

CONCLUSIONS

Although controlled, recreational ketamine use and related fatalities continue to increase. Consumers need to be more aware of the potentially fatal risks they face.

Group II metabotropic glutamate receptor (mGlu2 and mGlu3 ) roles in thalamic processing

BACKGROUND AND PURPOSE

As the thalamus underpins almost all aspects of behaviour, it is important to understand how the thalamus operates. Group II metabotropic glutamate (mGlu₂ /mGlu₃ ) receptor activation reduces inhibition in thalamic nuclei originating from the surrounding thalamic reticular nucleus (TRN). Whilst an mGlu₂ component to this effect has been reported, in this study, we demonstrate that it is likely, largely mediated via mGlu₃ .

EXPERIMENTAL APPROACH

The somatosensory ventrobasal thalamus (VB) is an established model for probing fundamental principles of thalamic function. In vitro slices conserving VB-TRN circuitry from wild-type and mGlu₃ knockout mouse brains were used to record IPSPs and mIPSCs. In vivo extracellular recordings were made from VB neurons in anaesthetised rats. A range of selective pharmacological agents were used to probe Group II mGlu receptor function (agonist, LY354740; antagonist, LY341495; mGlu₂ positive allosteric modulator, LY487379 and mixed mGlu₂ agonist/mGlu₃ antagonist LY395756).

KEY RESULTS

The in vitro and in vivo data are complementary and suggest that mGlu₃ receptor activation is largely responsible for potentiating responses to somatosensory stimulation by reducing inhibition from the TRN.

CONCLUSIONS AND IMPLICATIONS

mGlu₃ receptor activation in the VB likely enables important somatosensory information to be discerned from background activity. These mGlu₃ receptors are likely to be endogenously activated via 'glutamate spillover'. In cognitive thalamic nuclei, this mechanism may be of importance in governing attentional processes. Positive allosteric modulation of endogenous mGlu₃ receptor activation may therefore enhance cognitive function in pathophysiological disease states, such as schizophrenia, thus representing a highly specific therapeutic target.

Over-the-counter antihistamines in drug-related deaths: a population-based case series

Introduction

Antihistamines are not one of the medicine groups reported on in the Office for National Statistics drug-related death data. (1) However, there is concern that first-generation antihistamines are misused for their sedative properties. This is amplified by a recent social media challenge, which resulted in deaths due to diphenhydramine overdose. (2) The extent of the involvement of antihistamines in deaths is largely unknown.

Aim

We aimed to evaluate deaths related to antihistamines in England (2000–2019) by individual drug, medicine classification (POM, P, GSL), whether the drug was considered attributable to the death (known as implication rate), or incidental; and examine temporal trends.

Methods

Deaths are reported voluntarily by coroners to the National Programme on Substance Abuse Deaths (NPSAD) in cases where psychoactive drugs were detected at post-mortem and/or when the decedent was known to abuse drugs. NPSAD holds data on decedent demographics (gender, age, employment status, living arrangements), details pertaining to the death (cause(s) of death, manner of death, conclusion of inquest, toxicology reports) and past social and medical histories, including drugs prescribed. From this dataset, we extracted all cases where an antihistamine was detected at post-mortem between 2000 and 2019. We report descriptive statistics to describe the reporting of antihistamines in deaths.

Results

We identified 1666 antihistamine detections from 1537 individuals. The significant majority of these were sedative antihistamines which are classed as pharmacy medicines (P) (85.2%, p&lt;0.01); deaths where prescription-only antihistamines were detected represented fewer than 7.0% of cases. Despite an increasing trend for antihistamine detections in deaths over time, the proportion of deaths where the detected antihistamine was implicated in causing the death declined over the same period (average implication rate 2000–2005: 58.7%; 2014–2019: 28.4%). Whilst death was deemed accidental in the majority of cases (66.1%), a significant proportion of cases were concluded as suicide (20.9%, p&lt;0.01).Polydrug use was evident in the vast majority of cases (98.5%), with central nervous system depressants the most commonly co-administered substances (94.8% of cases).

Conclusion

We describe the first report regarding antihistamine-related mortality from England. From the NPSAD, we can obtain prescription source and toxicology reports, beyond those reported in national death data. Although incomplete, the response from coroners is good (89%), and provides sufficient cause for concern. The rising trend in antihistamine-related deaths may in-part be contributed to by the perceived negligible dangers associated with antihistamines, both from the general public and professionals. Awareness of the dangerous sedative properties that some antihistamines possess is however heightened in individuals who are deliberately seeking out these effects. An urgent review of sedating antihistamines currently assigned under the P classification is needed to achieve antihistamine harm reduction, balanced against the self-care they enable.

References

1. Office for National Statistics. Deaths related to drug poisoning in England and Wales: 2019 registration [internet]. 2020 [cited 18 Oct 2020]. Available from: https://www.ons.gov.uk/peoplepopulationandcommunity/birthsdeathsandmarriages/deaths/bulletins/deathsrelatedtodrugpoisoninginenglandandwales/2019registrations

2. US FDA. Benadryl (diphenhydramine): Drug Safety Communication - Serious Problems with High Doses of the Allergy Medicine. 2020.

Antihistamine-related deaths in England: Are the high safety profiles of antihistamines leading to their unsafe use?

AIMS

Antihistamines are routinely taken to control allergic reactions or sedation to induce sleep. There are, however, growing concerns regarding sedating antihistamine misuse. This research aims to evaluate deaths related to antihistamines in England occurring during 2000-2019.

METHODS

Cases reported to the National Programme on Substance Abuse Deaths from England occurring in 2000-2019 with antihistamine detections at postmortem were extracted for analysis.

RESULTS

In total, 1666 antihistamine postmortem detections were identified from 1537 cases. Sedating antihistamines available for purchase under pharmacist supervision but without need for a prescription (pharmacy-only medications) were present in a significant majority of cases (85.2%, P < .01). Despite an increasing trend for antihistamine-related deaths over time, the proportion of deaths where an antihistamine was implicated declined over the same period. Specific concerns with regards to the misuse of these pharmacy-only sedating antihistamines are raised with regards to the significant proportion of cases that were concluded as suicide (20.9%, P < .01), and the high prevalence of their use in combination with other central nervous system depressants (94.8% of cases).

CONCLUSION

This is the first report in over 40 years regarding antihistamine-related mortality from England. The rising trend in sedating antihistamine-related deaths may be contributed to by their increasing availability and the perceived negligible dangers associated with antihistamines, both from the general public and learned professionals. Awareness of the dangerous sedative properties that some antihistamines possess is, however, heightened in individuals deliberately seeking these effects. Urgent review of sedating antihistamines currently assigned under the pharmacy-only classification is needed to achieve antihistamine harm reduction.

A deadly trend in fentanyl fatalities (England, 1998-2017)

AIM

To identify trends in drug-related deaths associated with fentanyl and its derivatives, including novel variants, in England, 1998-2017.

METHODS

Case reports from the National Programme on Substance Abuse Deaths (NPSAD) where a pharmaceutical fentanyl or non-pharmaceutical fentanyl derivative (NPFD) was found at post-mortem and/or implicated in the death were extracted for analysis.

RESULTS

NPSAD has received case reports detailing 298 deaths in England from 1998-2017 where a fentanyl was found at post-mortem and/or implicated in the death. Hospital administered fentanyl is "very safe", whereas pharmaceutical fentanyls in the community, procured either legitimately via prescription or illegitimately, carry high risk of unintentional death. Deaths involving NPFDs, which possess extreme potencies in comparison to morphine, have drastically risen over the past three years, and correlate with an increasing number of available compounds. Males, and those with existing opioid abuse disorders, are particularly susceptible to death related to NPFD intake.

CONCLUSIONS

The increasing availability of both pharmaceutical fentanyls and NPFDs represents a serious risk to public health. Unintentional misuse of these compounds in England is contributing to the exponential increase in fentanyl-associated deaths that is being observed at the global scale.

Astrocytes modulate thalamic sensory processing via mGlu2 receptor activation

Astrocytes possess many of the same signalling molecules as neurons. However, the role of astrocytes in information processing, if any, is unknown. Using electrophysiological and imaging methods, we report the first evidence that astrocytes modulate neuronal sensory inhibition in the rodent thalamus.

We found that mGlu2 receptor activity reduces inhibitory transmission from the thalamic reticular nucleus to the somatosensory ventrobasal thalamus (VB): mIPSC frequencies in VB slices were reduced by the Group II mGlu receptor agonist LY354740, an effect potentiated by mGlu2 positive allosteric modulator (PAM) LY487379 co-application (30 nM LY354740: 10.0 ± 1.6% reduction; 30 nM LY354740 & 30 μM LY487379: 34.6 ± 5.2% reduction).

We then showed activation of mGlu2 receptors on astrocytes: astrocytic intracellular calcium levels were elevated by the Group II agonist, which were further potentiated upon mGlu2 PAM co-application (300 nM LY354740: ratio amplitude 0.016 ± 0.002; 300 nM LY354740 & 30 μM LY487379: ratio amplitude 0.035 ± 0.003).

We then demonstrated mGlu2-dependent astrocytic disinhibition of VB neurons in vivo: VB neuronal responses to vibrissae stimulation trains were disinhibited by the Group II agonist and the mGlu2 PAM (LY354740: 156 ± 12% of control; LY487379: 144 ± 10% of control). Presence of the glial inhibitor fluorocitrate abolished the mGlu2 PAM effect (91 ± 5% of control), suggesting the mGlu2 component to the Group II effect can be attributed to activation of mGlu2 receptors localised on astrocytic processes within the VB.

Gating of thalamocortical function via astrocyte activation represents a novel sensory processing mechanism. As this thalamocortical circuitry is important in discriminative processes, this demonstrates the importance of astrocytes in synaptic processes underlying attention and cognition.

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Thalamic inhibition is mediated by both neuronal and astrocytic mechanisms.

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Group II mGlu receptor (mGlu2/3) activation can modulate this thalamic inhibition.

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Thalamic astrocytes can be activated upon mGlu2 receptor stimulation.

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This process may enable relevant activity to be discerned from background noise.

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Targeting astrocytic mGlu2 receptors may therefore affect attention and cognition.

Advances in two photon scanning and scanless microscopy technologies for functional neural circuit imaging

Recent years have seen substantial developments in technology for imaging neural circuits, raising the prospect of large scale imaging studies of neural populations involved in information processing, with the potential to lead to step changes in our understanding of brain function and dysfunction. In this article we will review some key recent advances: improved fluorophores for single cell resolution functional neuroimaging using a two photon microscope; improved approaches to the problem of scanning active circuits; and the prospect of scanless microscopes which overcome some of the bandwidth limitations of current imaging techniques. These advances in technology for experimental neuroscience have in themselves led to technical challenges, such as the need for the development of novel signal processing and data analysis tools in order to make the most of the new experimental tools. We review recent work in some active topics, such as region of interest segmentation algorithms capable of demixing overlapping signals, and new highly accurate algorithms for calcium transient detection. These advances motivate the development of new data analysis tools capable of dealing with spatial or spatiotemporal patterns of neural activity, that scale well with pattern size.

Neuronal activity patterns in the mediodorsal thalamus and related cognitive circuits are modulated by metabotropic glutamate receptors

The mediodorsal thalamus (MD) likely plays an important role in cognition as it receives abundant afferent connections from the amygdala and prefrontal cortex (PFC). Indeed, disturbed activity within the MD is thought to precipitate cognitive deficits associated with schizophrenia. As compounds acting at the Group II metabotropic glutamate (mGlu) receptors (subtypes mGlu2/mGlu3) have efficacy in animal models of schizophrenia, we investigated whether a Group II agonist and an mGlu2 positive allosteric modulator (PAM) could modulate MD activity. Extracellular single-unit recordings were made in vivo from MD neurones in anaesthetised rats. Responses were elicited by electrical stimulation of the PFC and/or amygdala, with Group II compounds locally applied as required. The Group II agonist reduced inhibition evoked in the MD: an effect manifested as an increase in short-latency responses, and a decrease in long-latency burst-firing. This disinhibitory action of the Group II receptors in the MD represents a mechanism of potential therapeutic importance as increased inhibition in the MD has been associated with cognitive deficit-onset. Furthermore, as co-application of the mGlu2 PAM did not potentiate the Group II agonist effects in the MD, we suggest that the Group II disinhibitory effect is majority-mediated via mGlu3. This heterogeneity in Group II receptor thalamic physiology bears consequence, as compounds active exclusively at the mGlu2 subtype are unlikely to perturb maladapted MD firing patterns associated with cognitive deficits, with activity at mGlu3 receptors possibly more appropriate. Indeed, polymorphisms in the mGlu3, but not the mGlu2, gene have been detected in patients with schizophrenia.

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There is heterogeneity in Group II receptor physiology across thalamic nuclei.

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This differential distribution may facilitate multimodal thalamic nuclei functions.

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Group II receptor activation reduced burst firing via reducing thalamic inhibition.

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Increased thalamic inhibition precipitates impairments in cognitive function.

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Activating the Group II receptors may therefore enhance cognitive function.

Function of mGlu1 receptors in the modulation of nociceptive processing in the thalamus

As postsynaptic metabotropic subtype 1 (mGlu1) receptors are present in the thalamus, we have investigated the effect of potentiating and antagonising mGlu1 receptors on responses of thalamic neurones to noxious sensory stimulation. Extracellular recordings were made in vivo with multi-barrel iontophoretic electrodes from single neurones in the thalamus of urethane-anaesthetised rats. Responses to iontophoretic applications of the Group I mGlu agonist 3,5-dihydroxy-phenylglycine (DHPG) were selectively potentiated by co-application of the mGlu1 positive allosteric modulator Ro67-4853, whereas they were selectively reduced upon co-application of the mGlu1 receptor orthosteric antagonist LY367385. This indicates that thalamic DHPG responses are mediated primarily via mGlu1 receptors, consistent with the high postsynaptic levels of this receptor in the thalamus. Furthermore, potentiation of DHPG responses by Ro67-4853 were greater when the initial DHPG response was of a low magnitude. Ro67-4853 also potentiated responses of thalamic neurones to noxious thermal stimulation, whilst having little effect on the baseline activity of nociceptive neurones. By contrast, nociceptive responses were reduced by LY367385. In a further series of experiments we found that inactivation of somatosensory cortex by cooling resulted in a reduction of thalamic nociceptive responses. These results underline the importance of mGlu1 receptors in the processing of sensory information in the thalamus, particularly with respect to nociceptive responses. Furthermore, the involvement of mGlu1 receptors may reflect the activity of descending cortico-thalamic afferents.

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Pharmacological potentiation of mGlu1 receptors enhances nociceptive responses of thalamic neurones.

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Antagonism of mGlu1 receptors reduces nociceptive responses of thalamic neurones.

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Inactivation of somatosensory cortex reduces nociceptive responses of thalamic neurones.

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This suggests a role for mGlu1 receptors and cortico-thalamic pathways in nociceptive processing.

Effect of VGLUT inhibitors on glutamatergic synaptic transmission in the rodent hippocampus and prefrontal cortex

Vesicular glutamate transporters (VGLUTs) are known to be important in the uptake of glutamate into vesicles in the presynaptic terminal; thereby playing a role in synaptic function. VGLUT dysfunction has also been suggested in neurological and psychiatric disorders such as epilepsy and schizophrenia. A number of compounds have been identified as VGLUT inhibitors; however, little is known as to how these compounds affect synaptic transmission. We therefore investigated the effects of structurally unrelated VGLUT inhibitors on synaptic transmission in the rodent hippocampus and prefrontal cortex. In the CA1 and dentate gyrus regions of the in vitro slice preparation of mouse hippocampus, AMPA receptor-mediated field excitatory postsynaptic potentials (fEPSPs) were evoked in response to Schaffer collateral/commissural pathway stimulation. Application of the VGLUT inhibitors Rose Bengal (RB), Congo Red (CR) or Chicago Sky Blue 6B (CB) resulted in a concentration-related reduction of fEPSP amplitudes. RB (30μM) or CB (300μM) also depressed NMDA receptor-mediated responses in the CA1 region. The naturally occurring kynurenine Xanthurenic Acid (XA) is reported to be a VGLUT inhibitor. We found XA attenuated both AMPA and NMDA receptor-mediated synaptic transmission. The potency order of the VGLUT inhibitors was consistent with literature Ki values for VGLUT inhibition. Impaired glutamatergic neurotransmission is believed to contribute to schizophrenia, and VGLUTs have also been implicated in this disease. We therefore investigated the effect of VGLUT inhibition in the prefrontal cortex. Application of the VGLUT inhibitors RB or CB resulted in a concentration-dependent reduction in the amplitude of glutamate receptor-mediated fEPSPs recorded in layer V/VI in response to stimulation in the forceps minor. We conclude that VGLUT inhibitors can modulate glutamatergic synaptic transmission in the PFC and hippocampus. This could be important in the pathophysiology of nervous system disorders and might represent a target for developing novel pharmacological therapies.

Modulation of hippocampal synaptic transmission by the kynurenine pathway member xanthurenic acid and other VGLUT inhibitors

Xanthurenic acid (XA), an endogenous kynurenine, is a known vesicular glutamate transport (VGLUT) inhibitor and has also been proposed as an mGlu2/3 receptor agonist. Changes in these systems have been implicated in the pathophysiology of schizophrenia and other psychiatric disorders; however, little is known of how XA affects synaptic transmission. We therefore investigated the effects of XA on synaptic transmission at two hippocampal glutamatergic pathways and evaluated the ability of XA to bind to mGlu2/3 receptors. Field excitatory postsynaptic potentials (fEPSPs) were recorded from either the dentate gyrus (DG) or CA1 region of mouse hippocampal slices in vitro. Addition of XA to the bathing medium (1-10 mM) resulted in a dose-related reduction of fEPSP amplitudes (up to 52% reduction) in both hippocampal regions. In the DG, the VGLUT inhibitors Congo Red and Rose Bengal, and the mGlu2/3 agonist LY354740, also reduced fEPSPs (up to 80% reduction). The mGlu2/3 antagonist LY341495 reversed the LY354740 effect, but not the XA effect. LY354740, but not XA, also reduced DG paired-pulse depression. XA had no effect on specific binding of 1 nM [(3)H]LY341495 to membranes with human mGlu2 receptors. We conclude that XA can modulate synaptic transmission via a mechanism that may involve VGLUT inhibition rather than activation of mGlu2/3 receptors. This could be important in the pathophysiology of nervous system disorders including schizophrenia and might represent a target for developing novel pharmacological therapies.

Positive allosteric modulation reveals a specific role for mGlu2 receptors in sensory processing in the thalamus

Group II metabotropic glutamate receptor (mGlu) modulation of sensory processing in the rat ventrobasal thalamic nucleus (VB) has been extensively studied in vivo. However, it is not yet known what the relative contributions are of the Group II mGlu receptor subtypes (mGlu2 and mGlu3) to this modulation, nor to what extent these receptors may be activated under physiological conditions during this process. Using single-neurone recording in the rat VB in vivo with local application of the selective Group II agonist LY354740 and the subtype selective mGlu2 positive allosteric modulator (PAM) LY487379, our findings were twofold. Firstly, we found that there is an mGlu2 component to the effects of LY354740 on sensory responses in the VB. Secondly, we have demonstrated that application of the PAM alone can modulate sensory responses of single neurones in vivo. This indicates that mGlu2 receptors can be activated by endogenous agonist following physiological sensory stimulation. We speculate that the mGlu2 subtype could be activated under physiological stimulus-evoked conditions by 'glutamate spillover' from synapses between excitatory sensory afferents and VB neurones that can lead to a reduction in sensory-evoked inhibition arising from the thalamic reticular nucleus (TRN). We propose that this potential mGlu2 receptor modulation of inhibition could play an important role in discerning relevant information from background activity upon physiological sensory stimulation. Furthermore, this could be a site of action for mGlu2 PAMs to modulate cognitive processes.

Potentiation of sensory responses in ventrobasal thalamus in vivo via selective modulation of mGlu1 receptors with a positive allosteric modulator

Metabotropic glutamate subtype 1 (mGlu1) receptor is thought to play a role in synaptic responses in thalamic relay nuclei. The aim of this study was to evaluate the positive allosteric modulator (PAM) Ro67-4853 as a tool to modulate thalamic mGlu1 receptors on single thalamic neurones in vivo. Ro67-4853, applied by iontophoresis onto ventrobasal thalamus neurones of urethane-anaesthetised rats, selectively enhanced responses to the agonist (S)-3,5-dihydroxy-phenylglycine (DHPG), an effect consistent with mGlu1 potentiation. The PAM was also able to enhance maintained responses to 10 Hz trains of sensory stimulation of the vibrissae, but had little effect on responses to single sensory stimuli. Thus Ro67-4853 appears to be a highly selective tool that can be useful in investigating how mGlu1 receptor potentiation can alter neural processing in vivo. Our results show the importance of mGlu1 in sensory processing and attention mechanisms at the thalamic level and suggest that positive modulation of mGlu1 receptors might be a useful mechanism for enhancing cognitive and attentional processes.

Spectacle-mounted prisms as an aid in face-down positioning after vitrectomy surgery

PURPOSE

To report a modification in the design of bed spectacles to provide an aid for patients who undergo face-down positioning after vitrectomy with gas-fluid exchange and postoperative gas tamponade.

METHODS

New equipment design. Bed spectacles that use prisms to move the image 90 degrees around the horizontal meridian were modified by rotating the prisms in the frame 180 degrees and adding nosepads and cable temples. The spectacles were given to 12 patients for use during postoperative face-down positioning. A questionnaire was used to evaluate the helpfulness of the spectacles during face-down positioning.

RESULTS

Patients ranked the spectacles as "helpful" to "very helpful" with a mean and SD of 8.3+/-1.6 on a scale of 1 to 10, where 1 was "a hindrance" and 10 was "very helpful." Patients wore the spectacles an average of 5.7+/-4.5 hours a day (range, 1.5 to 15 hours).

CONCLUSION

Modified bed spectacles appear to be a portable aid to patients who undergo face-down positioning while sitting, standing, or prone.

Nuclear pore complex clustering and nuclear accumulation of poly(A)+ RNA associated with mutation of the Saccharomyces cerevisiae RAT2/NUP120 gene

To identify genes involved in the export of messenger RNA from the nucleus to the cytoplasm, we used an in situ hybridization assay to screen temperature-sensitive strains of Saccharomyces cerevisiae. This identified those which accumulated poly(A)+ RNA in their nuclei when shifted to the non-permissive temperature of 37 degrees C. We describe here the properties of yeast strains carrying mutations in the RAT2 gene (RAT - ribonucleic acid trafficking) and the cloning of the RAT2 gene. Only a low percentage of cells carrying the rat2-1 allele showed nuclear accumulation of poly(A)+ RNA when cultured at 15 degrees or 23 degrees C, but within 4 h of a shift to the nonpermissive temperature of 37 degrees C, poly(A)+ RNA accumulated within the nuclei of approximately 80% of cells. No defect was seen in the nuclear import of a reporter protein bearing a nuclear localization signal. Nuclear pore complexes (NPCs) are distributed relatively evenly around the nuclear envelope in wild-type cells. In cells carrying either the rat2-1 or rat2-2 allele, NPCs were clustered together into one or a few regions of the nuclear envelope. This clustering was a constitutive property of mutant cells. NPCs remained clustered in crude nuclei isolated from mutant cells, indicating that these clusters are not able to redistribute around the nuclear envelope when nuclei are separated from cytoplasmic components. Electron microscopy revealed that these clusters were frequently found in a protuberance of the nuclear envelope and were often located close to the spindle pole body. The RAT2 gene encodes a 120-kD protein without similarity to other known proteins. It was essential for growth only at 37 degrees C, but the growth defect at high temperature could be suppressed by growth of mutant cells in the presence of high osmolarity media containing 1.0 M sorbitol or 0.9 M NaCl. The phenotypes seen in cells carrying a disruption of the RAT2 gene were very similar to those seen with the rat2-1 and rat2-2 alleles. Epitope tagging was used to show that Rat2p is located at the nuclear periphery and co-localizes with yeast NPC proteins recognized by the RL1 monoclonal antibody. The rat2-1 allele was synthetically lethal with both the rat3-1/nup133-1 and rat7-1/nup159-1 alleles. These results indicate that the product of this gene is a nucleoporin which we refer to as Rat2p/Nup120p.

Mutation or deletion of the Saccharomyces cerevisiae RAT3/NUP133 gene causes temperature-dependent nuclear accumulation of poly(A)+ RNA and constitutive clustering of nuclear pore complexes

To identify genes whose products play potential roles in the nucleocytoplasmic export of messenger RNA, we isolated temperature-sensitive strains of Saccharomyces cerevisiae and examined them by fluorescent in situ hybridization. With the use of a digoxigen-tagged oligo-(dT)50 probe, we identified those that showed nuclear accumulation of poly(A)+ RNA when cells were shifted to the nonpermissive temperature. We describe here the properties of yeast strains bearing the rat3-1 mutation (RAT-ribonucleic acid trafficking) and the cloning of the RAT3 gene. When cultured at the permissive temperature of 23 degrees C, fewer than 10% of cells carrying the rat3-1 allele showed nuclear accumulation of poly(A)+ RNA, whereas approximately 70% showed nuclear accumulation of poly(A)+ RNA, whereas approximately 70% showed nuclear accumulation of poly(A)+ RNA after a shift to 37 degrees C for 4 h. In wild-type cells, nuclear pore complexes (NPCs) are distributed relatively evenly around the nuclear envelope. Both indirect immunofluorescence analysis and electron microscopy of rat3-1 cells indicated that NPCs were clustered into one or a few regions of the NE in mutant cells. Similar NPC clustering was seen in mutant cells cultured at temperatures between 15 degrees C and 37 degrees C. The RAT3 gene encodes an 1157-amino acid protein without similarity to other known proteins. It is essential for growth only at 37 degrees C. Cells carrying a disruption of the RAT3 gene were very similar to cells carrying the original rat3-1 mutation; they showed temperature-dependent nuclear accumulation of poly(A)+ RNA and exhibited constitutive clustering of NPCs. Epitope tagging of Rat3p demonstrated that it is located at the nuclear periphery and co-localizes with nuclear pore proteins recognized by the RL1 monoclonal antibody. We refer to this nucleoporin as Rat3p/Nup133p.

Social interaction effects on restrained eating

The eating behavior of college women scoring within either the above-average or middle ranges on the Restraint Scale was compared following brief social encounters with male students or other female students, or a no-encounter control situation. The eating of average restraint women was significantly depressed following interaction with a partner whom the subjects considered attractive. For high restraint women a nonsignificant tendency towards disinhibition of eating following interaction with an attractive other occurred. Personality ratings by partners indicated that high restraint women presented a distinct social persona to male, but not female, strangers in the brief experimental interaction.

Nuclear pore complex antigens delineate nuclear envelope dynamics in vegetative and conjugating Saccharomyces cerevisiae

In the yeast Saccharomyces cerevisiae, the nucleus undergoes dramatic shape changes during mitosis and mating. We have studied nuclear envelope dynamics during the processes of mitosis and conjugation using nuclear pore complexes as a marker for the nuclear envelope in wild-type cells and several cell-division-cycle (cdc) mutants. Three monoclonal antibodies are described that recognize nuclear pore complex-related antigens in S. cerevisiae. One of these antibodies, RL1, has been extensively characterized by Gerace and colleagues and recognizes nuclear pore complexes in mammalian and amphibian cells. By indirect immunofluorescence of yeast cells, all three antibodies yield a discontinuous nuclear rim stain. All three react with multiple nuclear-enriched proteins in immunoblots, including the nucleoporin protein encoded by the NSP1 gene. When the antibodies were used in immunofluorescence experiments on mating cells, the nuclear pore complex staining pattern proved to be a sensitive indicator of nuclear fusion. Nuclei with closely apposed spindle pole bodies and unfused nuclear envelopes could be readily distinguished. Marked shape changes were observed in nuclei during fusion and segregation of the diploid nucleus into the zygotic bud. In cdc14 and cdc15 mutants that arrest late in mitosis, the elongated nuclear envelope extension that stretches between daughter nuclei during telophase was preserved. In cytokinesis-defective mutants (cdc3, cdc10, cdc11 and cdc12), the elongated nuclear envelope was usually resolved into two daughter nuclei in the absence of cytokinesis. These results indicate that nuclear envelope division is mechanically distinguishable from chromosome segregation, nucleolar segregation and cytokinesis.

The NUF1 gene encodes an essential coiled-coil related protein that is a potential component of the yeast nucleoskeleton

In an attempt to identify structural components of the yeast nucleus, subcellular fractions of yeast nuclei were prepared and used as immunogens to generate complex polyclonal antibodies. One such serum was used to screen a yeast genomic lambda gt11 expression library. A clone encoding a gene called NUF1 (for nuclear filament-related) was identified and extensively characterized. Antibodies to NUF1 fusion proteins were generated, and affinity-purified antibodies were used for immunoblot analysis and indirect immunofluorescence localization. The NUF1 protein is 110 kD in molecular mass and localizes to the yeast nucleus in small granular patches. Intranuclear staining is present in cells at all stages of the cell cycle. The NUF1 protein of yeast is tightly associated with the nucleus; it was not removed by extraction of nuclei with nonionic detergent or salt, or treatment with RNAse and DNAse. Sequence analysis of the NUF1 gene predicts a protein 945 amino acids in length that contains three domains: a large 627 residue central domain predicted to form a coiled-coil structure flanked by nonhelical amino-terminal and carboxy-terminal regions. Disruption of the NUF1 gene indicates that it is necessary for yeast cell growth. These results indicate that NUF1 encodes an essential coiled-coil protein within the yeast nucleus; we speculate that NUF1 is a component of the yeast nucleoskeleton. In addition, immunofluorescence results indicate that mammalian cells contain a NUF1-related nuclear protein. These data in conjunction with those in the accompanying manuscript (Yang et al., 1992) lead to the hypothesis that an internal coiled-coil filamentous system may be a general structural component of the eukaryotic nucleus.

Interactions of misfolded influenza virus hemagglutinin with binding protein (BiP)

We have characterized the association between the binding protein, BiP (also known as GRP 78), and misfolded forms of the influenza virus hemagglutinin precursor, HA0. BiP is a heat-shock-related protein that binds to unassembled immunoglobulin heavy chain and to a variety of misfolded proteins in the lumen of the ER. A small fraction (5-10%) of newly synthesized HA0 in CV-1 cells was found to be misfolded and retained in the ER. When glycosylation was blocked with tunicamycin, all of the HA0 produced was similarly misfolded. The misfolded HA0 was retained as relatively small (9-25-S) complexes associated with BiP. In these complexes the top domains of HA0 were correctly folded judging by their reactivity with monoclonal antibodies, but the polypeptides were cross-linked via anomalous interchain disulfides. The association with BiP was non-covalent and easily broken by warming to 37 degrees C or by adding ATP to the lysate. Pulse-chase experiments showed that HA0's self-association into complexes occurred immediately after synthesis and was followed rapidly by BiP association. The misfolded, BiP-associated HA0 was not transported to the plasma membrane but persisted as complexes in the ER for a long period of time before degradation (t1/2 = 6 h). The results suggested that BiP may be part of a quality control system in the ER and that one of its functions is to detect and retain misfolded proteins.

Folding, trimerization, and transport are sequential events in the biogenesis of influenza virus hemagglutinin

Results from several systems indicate that correct protein folding and subunit assembly correlate with the transport of membrane and secretory proteins from the endoplasmic reticulum (ER) to the Golgi complex. Because the site of oligomer assembly and its precise relationship to intracellular transport remain unclear, we have studied in detail the folding and trimerization of the influenza virus hemagglutinin (HA0) relative to its transport from ER to Golgi. Trimerization and transport were analyzed using several different methods, including transport inhibitors, temperature blocks, semi-intact cells, in vitro protein translocation, and immunocytochemistry. Taken together, the results clearly demonstrate that trimerization occurs at a point prior to exit from the ER. Before assembly, HA0 monomers were extensively folded and possessed intramolecular disulfide bonds, but monomers were not transported to the cis Golgi compartment. Thus, hemagglutinin progresses through at least two intermediate states before transport to the Golgi: highly folded monomers and trimers that have not yet left the ER.

Assembly of influenza hemagglutinin trimers and its role in intracellular transport

The hemagglutinin (HA) of influenza virus is a homotrimeric integral membrane glycoprotein. It is cotranslationally inserted into the endoplasmic reticulum as a precursor called HA0 and transported to the cell surface via the Golgi complex. We have, in this study, investigated the kinetics and cellular location of the assembly reaction that results in HA0 trimerization. Three independent criteria were used for determining the formation of quaternary structure: the appearance of an epitope recognized by trimer-specific monoclonal antibodies; the acquisition of trypsin resistance, a characteristic of trimers; and the formation of stable complexes which cosedimented with the mature HA0 trimer (9S20,w) in sucrose gradients containing Triton X-100. The results showed that oligomer formation is a posttranslational event, occurring with a half time of approximately 7.5 min after completion of synthesis. Assembly occurs in the endoplasmic reticulum, followed almost immediately by transport to the Golgi complex. A stabilization event in trimer structure occurs when HA0 leaves the Golgi complex or reaches the plasma membrane. Approximately 10% of the newly synthesized HA0 formed aberrant trimers which were not transported from the endoplasmic reticulum to the Golgi complex or the plasma membrane. Taken together the results suggested that formation of correctly folded quaternary structure constitutes a key event regulating the transport of the protein out of the endoplasmic reticulum. Further changes in subunit interactions occur as the trimers move along the secretory pathway.

Bacillus Calmette-Guérin-activated murine macrophages kill syngeneic melanoma cells under strict anaerobic conditions

We have studied the spontaneous killing of B5(59) melanoma cells by Bacillus Calmette-Guérin (BCG)-elicited macrophages under strictly anaerobic conditions to investigate the role of oxygen in macrophage-mediated cytotoxicity. The number of melanoma cells capable of forming colonies after aerobic or anaerobic incubation with BCG-macrophages was used as the index of cytotoxicity. The BCG-macrophages killed melanoma cells regardless of the amount of oxygen present. The killing observed was proportional to the ratio of effector cells added; a ratio of 25:1 effector to target cells was required to achieve nearly 90% cytotoxicity both aerobically and anaerobically. This cytotoxicity was not dependent on a diffusible macrophage product nor on alteration of the medium by macrophages, since tumor cells incubated in the same culture medium, but not in contact with a mixed population of tumor cells and macrophages, were not killed. These results also indicated that macrophage-mediated cytotoxicity was dependent on macrophage-tumor cell contact. The mechanism responsible for the oxygen-independent cytotoxicity is unknown at present.

Regulation of human natural killing. I. The role of monocytes, interferon, and prostaglandins

We have found that human endogenous natural killer activity as measured in a rapid 51Cr release assay is unaffected by the presence of monocytes. Moreover, stimulation of natural killer cells by poly I:C is independent of monocytes. In contrast, the presence of monocytes in a mixed population of mononuclear cells that have been stimulated by poly I:C suppresses NK activity. The suppression is shown to be partially reversible if indomethacin (10(-6) M) is added to the cultures during stimulation. Culture supernatants of monocytes stimulated with poly I:C are shown to contain PGE1 in a radioimmunoassay, and have NK inhibitory activity comparable to that obtained with exogenous PGE1 added to NK assays at a concentration range of 10(-7) to 10(-9) M. Culture supernatants from poly I:C-stimulated monocytes do not have detectable levels of antiviral activity. In contrast, plastic nonadherent cells stimulated with poly I:C produce significant levels of interferon (100 to 200 U/ml/2 x 10(6) cells) but almost undetectable amounts of PGE. Supernatants of nonadherent cells incubated with indomethacin (10(-6) M) alone augment NK activity. Taken together, the results suggest that stimulation of mononuclear cells with poly I:C is dependent on and regulated by the relative levels of interferon produced by lymphocytes and PGE produced by monocytes.

Regulation of human natural killing. I. The role of monocytes, interferon, and prostaglandins

We have found that human endogenous natural killer activity as measured in a rapid 51Cr release assay is unaffected by the presence of monocytes. Moreover, stimulation of natural killer cells by poly I:C is independent of monocytes. In contrast, the presence of monocytes in a mixed population of mononuclear cells that have been stimulated by poly I:C suppresses NK activity. The suppression is shown to be partially reversible if indomethacin (10(-6) M) is added to the cultures during stimulation. Culture supernatants of monocytes stimulated with poly I:C are shown to contain PGE1 in a radioimmunoassay, and have NK inhibitory activity comparable to that obtained with exogenous PGE1 added to NK assays at a concentration range of 10(-7) to 10(-9) M. Culture supernatants from poly I:C-stimulated monocytes do not have detectable levels of antiviral activity. In contrast, plastic nonadherent cells stimulated with poly I:C produce significant levels of interferon (100 to 200 U/ml/2 x 10(6) cells) but almost undetectable amounts of PGE. Supernatants of nonadherent cells incubated with indomethacin (10(-6) M) alone augment NK activity. Taken together, the results suggest that stimulation of mononuclear cells with poly I:C is dependent on and regulated by the relative levels of interferon produced by lymphocytes and PGE produced by monocytes.