Deciphering the impact of microenvironmental factors on cuticular hydrocarbon degradation in Lucilia sericata empty Puparia: Bridging ecological and forensic entomological perspectives using machine learning models

Blow flies (Calliphoridae) play essential ecological roles in nutrient recycling by consuming decaying organic matter. They serve as valuable bioindicators in ecosystem management and forensic entomology, with their unique feeding behavior leading to the accumulation of environmental pollutants in their cuticular hydrocarbons (CHCs), making them potential indicators of exposure history. This study focuses on CHC degradation dynamics in empty puparia of Lucilia sericata under different environmental conditions for up to 90 days. The three distinct conditions were considered: outdoor-buried, outdoor-above-ground, and indoor environments. Five predominant CHCs, n-Pentacosane (n-C25), n-Hexacosane (n-C26), n-Heptacosane (n-C27), n-Octacosane (n-C28), and n-Nonacosane (n-C29), were analyzed using Gas Chromatography-Mass Spectrometry (GC-MS). The findings revealed variations in CHC concentrations over time, influenced by environmental factors, with significant differences at different time points. Correlation heatmap analysis indicated negative correlations between weathering time and certain CHCs, suggesting decreasing concentrations over time. Machine learning techniques Support Vector Machine (SVM), Multilayer Perceptron (MLP), and eXtreme Gradient Boosting (XGBoost) models explored the potential of CHCs as age indicators. SVM achieved an R-squared value of 0.991, demonstrating high accuracy in age estimation based on CHC concentrations. MLP also exhibited satisfactory performance in outdoor conditions, while SVM and MLP yielded unsatisfactory results indoors due to the lack of significant CHC variations. After comprehensive model selection and performance evaluations, it was found that the XGBoost model excelled in capturing the patterns in all three datasets. This study bridges the gap between baseline and ecological/forensic use of empty puparia, offering valuable insights into the potential of CHCs in environmental monitoring and investigations. Understanding CHCs' stability and degradation enhances blow flies' utility as bioindicators for pollutants and exposure history, benefiting environmental monitoring and forensic entomology.

Comparison of all completed suicides in Frankfurt am Main (Hessen) before and during the early COVID-19 pandemic

To research the effect of the COVID-19 pandemic on mental health, the prevalence and characteristics of all completed suicides in the city of Frankfurt am Main were compared for a 10-month period before the pandemic (March 2019-December 2019) with one during the early pandemic (March 2020-December 2020). Medicolegal data collected in the context of the FraPPE suicide prevention project were evaluated using descriptive statistical methods. In total, there were 81 suicides during the early pandemic period, as opposed to 86 in the pre-pandemic period. Though statistically not significant, the proportion of male suicides (73%) was higher during the early pandemic period than before (63%). The age-at-death was comparable in the pre-pandemic and pandemic periods (average, 54.8 vs. 53.1 years). Between these two periods, there was no difference in respect to the three most commonly used suicide methods by men: fall from a height (26% vs. 22%), intoxication, and strangulation (each 24% vs. 19%). For women, there was, however, a shift in methods from strangulation (38%), intoxication (28%), and fall from a height (19%) to fall from a height (50%), strangulation (18%), intoxication, and collision with a rail vehicle (14% each). There was a trend towards more suicides among non-German nationals during the early pandemic (suicide rate/100,000 inhabitants: German, 14.3 vs. 11.5; non-German, 4.4 vs. 8.8). Before the pandemic, 54% of the suicides were known to have a mental illness in contrast to 44% during the early pandemic. Overall, no increase in completed suicides could be observed in Frankfurt am Main during the early pandemic.

Cuticular hydrocarbons as weathering biomarkers of empty puparia of the forensically important blowfly Calliphora vicina Robineau-Desvoidy, 1830 (Diptera: Calliphoridae) in soil v/s under room conditions

Forensic entomology uses the age of insects, such as blow flies, to determine a minimum post-mortem interval (PMImin). Recent research has focused on using the analysis of specific cuticular hydrocarbons (CHCs) in adult insects and their empty puparia to estimate their age, as it has been shown that their profile changes are consistent with age. The current work is based on the weathering of five CHCs from empty puparia of Calliphora vicina that were stored in soil (field/outdoor) and non-soil (room/indoor conditions) based pupariation media for a total of six months. The experiment was conducted in a controlled environment chamber at a constant temperature of 25 ± 2 °C under constant darkness. Gas chromatography-mass spectrometry (GC-MS) was used to analyze the cuticular hydrocarbons after they were extracted in n-Hexane. n-Pentacosane, n-Hexacosane, n-Heptacosane, n-Octacosane, and n-Nonacosane were the five CHCs investigated. Results showed that CHCs weathered more quickly in the soil than in the non-soil environment. It was also found that the abundance of Heptacosane increased in the samples during the fifth month when stored in a non-soil medium, while the abundances of all five CHCs were not detected after eight weeks onwards in soil pupation medium.

Missed chances? Sequestration and non-sequestration of alkaloids by moths (Lepidoptera)

Some butterflies and moths sequester and retain noxious phytochemicals for defence against predators. In the present study, three moth species, the garden tiger moth, Arctia caja, the death hawk moth, Acherontia atropos, and the oleander hawk moth, Daphnis nerii, were tested whether they sequester alkaloids from their host plants. Whereas A. caja consistently sequestered atropine from Atropa belladonna, also when atropine sulfate was added to the alkaloid-free diet of the larvae, A. atropos and D. nerii were found to be unable to sequester alkaloids, neither atropine nor eburnamenine from Vinca major, respectively. Instead of acquiring toxicity as chemical defence, nocturnal lifestyle and cryptic attitudes may improve their chances of survival.

Analysis of tetramisole metabolites- Is "Aminorex" found in Forensic Samples of Cocaine Users actually 4-Phenyl-2-imidazolidinone?

Phenyltetrahydroimidazothiazole (PTHIT, tetramisole) is a common adulterant in cocaine samples. Little is known on its human metabolism. p-hydroxy-PTHIT has long been the only proven phase-I-metabolite. Another putative metabolite is the stimulant aminorex. However, data on its analytical proof is rare and contradictory. Even less known is its constitutional isomer 4-phenyl-2-imidazolidinone which has only been proven in animal samples so far. Aim of the study was to get insight into the metabolism of PTHIT after controlled nasal uptake of PTHIT and in real forensic cocaine/benzoylecgonine-positive samples. A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was validated for quantification of 4-phenyl-2-imidazolidinone and p-hydroxy-PTHIT (LOQ 0.05 ng/mL each). Selectivity was ensured for 4-phenyl-2-imidazolidinone and aminorex (LOD 0.05 ng/mL). After controlled nasal uptake of tetramisole (10 mg, n=3) a shorter half-life for p-hydroxy-PTHIT (3.4-5.8 h) was determined than for 4-phenyl-2-imidazolidinone (14.0-15.9 h). p-hydroxy-PTHIT (33%) and 4-phenyl-2-imidazolidinone (51%) were also detected in serum samples from cocaine users tested previously positive for PTHIT (n=73). Aminorex was never detected. The potential of misinterpreting 4-phenyl-2-imidazolidinone as aminorex was tested using a gas chromatography-mass spectrometry (GC-MS) method used in literature and an in-house liquid chromatography-time-of-flight mass spectrometry (LC-QTOF) screening-method. Using GC-MS the analysed bis-trimethylsilyl-derivatives cannot be differentiated due to co-elution. Both substances were chromatographically separated using the LC-QTOF method, but library comparison workflows misinterpreted 4-phenyl-2-imidazolidinone as aminorex. It seems likely that aminorex, which was allegedly identified as a metabolite of PTHIT in samples of cocaine users in previous studies, is in fact 4-phenyl-2-imidazolidinone.

Euthanasie im Nationalsozialismus – Untersuchungen an drei Skeletten der Kriegsgräberstätte Idstein-Kalmenhof (Hessen)

Hintergrund

Der Kalmenhof wurde 1888 vom „Verein für die Idiotenanstalt zu Idstein“ gegründet. Während der NS-Zeit wurden in der „Kinderfachabteilung“ hunderte Kinder und Jugendliche von Ärzten und Pflegern getötet.

Material und Methoden

Nachdem ein historisches Gutachten und Georadaruntersuchungen Hinweise auf Gräber außerhalb einer als Kriegsgräberstätte ausgewiesenen Fläche erbrachte, erfolgten im Sommer 2020 Grabungen.

Ergebnisse

Außerhalb der Kriegsgräberstätte fanden sich keine Gräber. Innerhalb des Areals wurde eine Mehrfachbestattung von drei Individuen in einer 160 × 65 cm großen Grube entdeckt. Die knöchernen Überreste wurden exhumiert und makroskopisch, radiologisch, toxikologisch und molekulargenetisch untersucht. Zwei Individuen waren männlich, das Sterbealter betrug etwa 2,0 bis 2,25 Jahre und 2,5 Jahre. Das dritte Individuum war eine Jugendliche, die Untersuchungen ihrer sterblichen Überreste erbrachten Hinweise auf wiederholte und längere Zeit bestehende Phasen mit unzureichender Nährstoffversorgung. An keinem der Individuen fanden sich Zeichen einer körperlichen Behinderung, prä- oder perimortale Verletzungen. Die toxikologischen Untersuchungen verliefen für alle Individuen negativ. Für die beiden kindlichen Skelette konnte ein vollständiges STR-Profil erstellt werden, an dem jugendlichen Skelett gelang lediglich eine Geschlechtsbestimmung.

Diskussion

Die Ergebnisse stützen historische Angaben, wonach Gräber mehrfach belegt wurden. Demgegenüber war eine Unterteilung des Friedhofes nach dem Sterbealter nicht nachvollziehbar, ebenso wenig, dass sich auf angrenzenden Grundstücken Gräber befinden. Durch die gewonnenen Erkenntnisse wurde ein konkreter Identitätsverdacht für die drei Individuen erarbeitet. Die knöchernen Überreste wurden am Volkstrauertag 2020 im Rahmen einer Gedenkveranstaltung wieder beigesetzt.

Variant interpretation in molecular autopsy: a useful dilemma

Sudden cardiac death (SCD) in adolescents and young adults may be the first manifestation of an inherited arrhythmic syndrome. Thus identification of a genetic origin in sudden death cases deemed inconclusive after a comprehensive autopsy and may help to reduce the risk of lethal episodes in the remaining family. Using next-generation sequencing (NGS), a large number of variants of unknown significance (VUS) are detected. In the majority of cases, there is insufficient evidence of pathogenicity, representing a huge dilemma in current genetic investigations. Misinterpretation of such variants may lead to inaccurate genetic diagnoses and/or the adoption of unnecessary and/or inappropriate therapeutic approaches. In our study, we applied current (ACMG) recommendations for variant classification in post-mortem genetic screening of a cohort of 56 SCD victims. We identified a total 53 rare protein-altering variants (MAF < 0.2%) classified as VUS or worse. Twelve percent of the cases exhibited a clinically actionable variant (pathogenic, likely pathogenic or VUS – potentially pathogenic) that would warrant cascade genetic screening in relatives. Most of the variants detected by means of the post-mortem genetic investigations were VUS. Thus, genetic testing by itself might be fairly meaningless without supporting background data. This data reinforces the need for an experienced multidisciplinary team for obtaining reliable and accountable interpretations of variant significance for elucidating potential causes for SCDs in the young. This enables the early identification of relatives at risk or excludes family members as genetic carriers. Also, development of adequate forensic guidelines to enable appropriate interpretation of rare genetic variants is fundamental.

Endogenous formation of 1-propanol and methanol after consumption of alcoholic beverages

INTRODUCTION

In cases of drunk-driving, allegations that alcohol has been consumed after the incident, are proved by analyzing congener alcohols in the blood sample. 1-Propanol, one of the main congener compounds, was tested, whether it is also endogenously formed when a person has consumed alcoholic beverages.

METHODS

Eleven male and 13 female volunteers consumed congener-free vodka (37.5 vol% ethanol, individual doses: 0.15-0.32 l) within one hour. Blood samples were taken up to 10 h and analyzed for ethanol and congener alcohols by headspace gas chromatography-mass spectrometry.

RESULTS

Ethanol concentrations reached in blood a maximum of 0.65-1.23 g/l and decreased by 0.18 g/l/h (median values). Of the congener alcohols analyzed, only methanol and 1-propanol were detected in the plasma samples of all subjects. The endogenous methanol concentration increased from 0.66 mg/l by 0.22 mg/l/h to 2.19 mg/l (medians). 1-Propanol was not detected prior to alcohol consumption. Maximum concentrations of 0.10-0.32 mg/L were measured after 1.0-4.5 h. A plateau of the 1-propanol concentration was observed in the plasma samples of the 18 subjects lasting for 0.5-4.0 h and this alcohol was completely eliminated at ethanol concentrations of 0.17 g/l (median, range 0.03-0.55 g/l).

CONCLUSION

The results of the study confirm the formation of 1-propanol after consumption of 1-propanol-free beverages, which should be taken into account when evaluating its concentration.

Assessment of adherence to diuretics and β-blockers by serum drug monitoring in comparison to urine analysis

Purpose: Toxicological screenings for identifying antihypertensive drugs proved to be a useful tool for assessing adherence. However, misinterpretation may occur in case of highly metabolised drugs with low renal excretion, as well as for drugs with a prolonged detectability. The aim of the present study was to compare a recently developed therapeutic drug monitoring (TDM) method based on serum concentrations to an urine drug detection method for assessing adherence in outpatients.Materials and methods: Corresponding urine and blood samples were obtained at the same time from 26 outpatients without supervised medication. Urine and serum analyses were performed using established high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) methodologies. Adherence was assumed if drugs were detectable in urine or if serum concentrations were above individually calculated lower dose-related concentrations (DRC) or literature-based therapeutic reference ranges (TRR) used as cut-off, respectively.Results: The identification of analytes in urine as well as the quantitative serum assay were performed for atenolol (n = 6 patients), bisoprolol (n = 8), nebivolol (n = 6), canrenone (n = 6, metabolite of spironolactone), hydrochlorothiazide (n = 12) and furosemide (n = 2). On the basis of drug detectability in urine, adherence was assumed in 88% of prescriptions. In 81% (DRC) and 50% (TRR) of the serum analyses the cut-off value was exceeded, which confirms patients' adherence in a lower number. Differences in adherence rates were found in five patients, mainly for β-blockers.Conclusion: This study suggests that assessment of adherence can be performed more precisely on the basis of serum drug concentrations with individually calculated lower DRC than by using the TRR or qualitative urinalysis.

A local neighborhood volunteer network improves response times for simulated cardiac arrest

AIM

Each minute is crucial in the treatment of out-of-hospital cardiac arrest (CA). Immediate chest compressions and early defibrillation are keys to good outcomes. We hypothesized that a coordinated effort of alerting trained local neighborhood volunteers (vols) simultaneously with 911 activation of professional EMS providers would result in substantial decreases in call-to-arrival times, leading to earlier CPR and defibrillation.

METHODS

We developed a program of simultaneously alerting CPR- and AED-trained neighborhood vols and the local EMS system for CA events in a retirement residential neighborhood in Southern Arizona, encompassing approximately 440 homes. The closest EMS station is 3.3 miles from this neighborhood. Within this neighborhood, 15 vols and the closest EMS station were involved in multiple days of mock CA notifications and responses.

RESULTS

The two groups differed significantly in distance to the mock CA event and in response times. The volunteers averaged 0.3 ± 0.2 miles from the mock CA incidences while the closest EMS station averaged 3.4 ± 0.1 miles away (p < 0.0001). Response times (time from call to arrival) also differed. Two volunteers, one bringing an AED, averaged 1 min 38 s ± 53 s in Phase 1, while it took the EMS service an average of 7 min 20 s ± 1 min 13 s to arrive on scene; p < 0.0001.

CONCLUSION

Local neighborhood volunteers were geographically closer and arrived significantly sooner at the mock CA scene than did the EMS service. The approximate time savings from call to arrival with the volunteers was 4-6 min.

Adherence to antihypertensive drug treatment in patients with apparently treatment-resistant hypertension in the INSPiRED pilot study

PURPOSE

Drug adherence may be a major problem in the therapy of hypertension and in the diagnosis of therapy resistance. Adherence can be assessed by indirect methods or by direct methods like drug detection in urine with liquid chromatography-mass spectrometric methods.

MATERIALS AND METHODS

The current analysis included patients with apparently treatment- resistant hypertension (TRH) referred for renal denervation (RDN) and included in the the INSPiRED pilot trial (NCT01505010). Adherence was repeatedly assessed by toxicological urine analysis over a time range of up to 17 months in a total of 18 patients.

RESULTS

In the first urine samples of 18 patients the adherence rate (percentage of number of detected vs. prescribed medical drugs) ranged from 0 to 100% with a median of 73.2%. In further urine samples collected during the following up to 17 months every individual patient exhibited considerable changes in the adherence rate, neither a constancy nor a tendency could be deduced.

CONCLUSIONS

Urine analysis results exhibit variation over time and an assessment at a certain time point cannot be regarded as representative or predictor for future behavior. Therefore, it appears necessary to perform drug adherence testing repeatedly over time.

Coping with noxious effects of quinine by praying mantids (Mantodea) and spiders (Araneae)

Because of its bitter taste, quinine elicits strong antifeedant and toxic effects in animals including arthropods. In the present study, two mantis, Sphodromantis viridis, Hierodula membranacea, and two spider species, Nephila edulis, Selenocosmia javanensis, were offered a quinine solution or prey (crickets) contaminated or injected with quinine, which they ingested and survived without apparent toxic symptoms. Analysis of their faeces and, in the case of spiders, of silk from their web revealed that quinine was excreted over a period of 8-12 (mantids) or 7 days (spiders). Interestingly, the silk glands of the spiders served as an additional excretory organ of quinine. Both, mantids and spiders were shown to tolerate high amounts of quinine in their prey. Obviously, the bitter taste of this compound is not perceived by their gustatory receptors and consequently triggers no aversive reactions.

Poor sequestration of toxic host plant cardenolides and their rapid loss in the milkweed butterfly Danaus chrysippus (Lepidoptera: Nymphalidae: Danainae: Danaini)

Butterflies of the genus Danaus are known to sequester toxic cardenolides from milkweed host plants (Apocynaceae). In particular, Danaus plexippus efficiently sequesters and stores these compounds, whereas D. chrysippus, is considered to poorly sequester cardenolides. To estimate its sequestration capability compared with that of D. plexippus, larvae of both species were jointly reared on Asclepias curassavica and the major cardenolides of the host plant, calotropin and calactin, were analyzed in adults sampled at different time intervals after eclosion. Both cardenolides were detected in body and wings of D. plexippus. Whereas the calotropin-concentration remained constant over a period of 24 days, that of calactin steadily decreased. In the body, but not in the wings of D. chrysippus, calactin only was detected in low amounts, which was then almost completely lost during the following 8 days after eclosion, suggesting that in contrast to D. plexippus, cardenolides seem to be less important for that butterfly's defence against predators.

[Drinking study on the pharmacokinetics of the grappa congener 2-butanol]

A drinking study on the pharmacokinetics of the typical grappa congeners 2-butanol and 2-butanone (methyl ethyl ketone) was performed. It was expected that the concentration ratio might provide a means to estimate the time of ingestion of a grappa beverage. Twelve subjects drank a volume of the grappa "Vecchio di Prosecco" (42 vol%) to reach a blood alcohollevel of 1.20 %o. In the congener analyses in serum, a median 2-butanol concentration of 0.79 mg/1 (range 0.45-1.34 mg/1) and of 1.01 mg/I (0.44-1.62 mg/1) for 2-butanone were measured. The concentration-time curve was biphasic starting with a slow and plateau-like elimination. However, considerable inter-individual differences were observed. Only in 3 subjects, a 2-butanol : 2-butanone ratio below 1 suggested ingestion within the last 6 hours. The majority of the subjects exhibited higher concentrations of 2-butanone than of 2-butanol such that the ratio was always smaller than 1. According to the present results the concentrations of 2-butanol and 2-butanone or their ratio do not provide a reliable basis to draw conclusions on the time of grappa ingestion.

Field study to detect illicit and medicinal drugs in car drivers in Southern and Western Hesse

In the present study, immunochemical tests (Mahsan DrugInspector, DOA4, DOA8, DOA10, Protzek) as well as the detection rate of police checks were evaluated. Urine and blood samples of suspected car drivers were analysed by chromatography-mass spectrometry. Additionally, anonymised urine samples were analysed on a voluntary basis in cases where no legal proceedings were initiated. Toxicological analyses (total unknown screening) were performed using gas chromatography-mass spectrometry (GC-MS) after hydrolysis, acidic and alkaline extraction and derivatization. A data base for screening 9000 substance entries was applied. In addition, urine samples were analysed using liquid chromatography/ time-of-flight mass spectrometry (HPLC-ToF-MS) to screen psychiatric and narcotic drugs. In total, samples of 154 suspects were analysed, of these, 46 samples for no actual reason. In 5 of the latter samples, forensically relevant substances were detected; in two cases the consumption of illicit drugs, i. e. cannabis and methamphetamine, was proved. Of the 154 suspects, 108 were charged with driving under the influence of drugs; in samples of 103 of these cases, illicit drugs were found. Immunochemical pretesting showed posi- tive results in 97 of the 108 cases; in 6 samples, psychiatric drugs (citalopram, doxepin, promethazine, mirtazapine, fluoxetine, venlafaxine) were later identified, which are not detectable by ordinary pretesting systems. Police officers successfully identified 95.4 % of the suspects as drug consumers, which is an excellent result. In practice, pretesting of urine samples using immunochemical techniques proved to be very reliable. The Protzek system in particular corresponded well with the results of the chromatographic analyses. In conclusion, systematic chromatographic-mass spectrometric analysis of urine samples of suspects is recommended to identify car drivers consuming illicit drugs and to obtain data usable in legal proceedings (e. g. suspending of the driving license), which is not always possible when using blood samples in cases of drugs consumed some time ago.

Self-induced illegal abortion with Rivanol®: A medicolegal-toxicological case report

Approximately during the 30th week of pregnancy, a woman gave birth to a still-born child in a hospital. After first citing an extraneous cause for the premature still-birth, the woman later admitted to having self-induced the abortion by injecting the antiseptic Rivanol^® (active agent: ethacridine lactate) through her abdominal wall into the amniotic cavity. The investigating authorities ordered an autopsy of the fetus along with additional toxicological investigations. To the naked eye, no obvious cause of death was apparent. The main autopsy findings were four skin defects (puncture/stabbing wounds) on the ball of the fetus's left thumb, with slight bleeding around the punctures and into the underlying fatty tissue, and a yellowish discoloration of the fetus's body surface, especially of the umbilical cord and fingernails. On basis of the results, the child would have been viable. Femoral vein blood and urine from the fetus were analyzed for ethacridine, as were an amniotic fluid sample and maternal blood and urine samples, which had been collected as evidence. The concentration of ethacridine in the amniotic fluid was 16mg/l. In the postmortem fetal blood and urine samples, the concentrations were 0.36mg/l and 0.34mg/l, respectively, while concentrations of 0.091mg/l and 0.42mg/l, respectively, were found in the serum and urine samples from the mother. In many countries, foremost in China, ethacridine lactate, to which both mother and child are exposed, is widely used as safe abortion method. Although the ethacridine concentrations found in blood and urine samples of the mother in our case are consistent with published values, we believe to be the first to report postmortem ethacridine concentrations in a fetus. While exposure to ethacridine is not toxicologically relevant for the mother, it is fatal for the fetus because it causes the placental decidua capsularis to separate from the decidua parietalis or decidua placentalis, respectively. Prostaglandins that are then produced induce labor. In medicolegal contexts, the proof for an abortion through the administration of ethacridine lactate lies in the typical yellow discoloration of the fetus in conjunction with the toxicological demonstration of the substance in fetal body fluids, and if possible also in maternal body fluids.

Pharmacoepigenetics of the role of DNA methylation in μ-opioid receptor expression in different human brain regions

AIM

Exposure to opioids has been associated with epigenetic effects. Studies in rodents suggested a role of varying degrees of DNA methylation in the differential regulation of μ-opioid receptor expression across the brain.

METHODS

In a translational investigation, using tissue acquired postmortem from 21 brain regions of former opiate addicts, representing a human cohort with chronic opioid exposure, μ-opioid receptor expression was analyzed at the level of DNA methylation, mRNA and protein.

RESULTS & CONCLUSION

While high or low μ-opioid receptor expression significantly correlated with local OPRM1 mRNA levels, there was no corresponding association with OPRM1 methylation status. Additional experiments in human cell lines showed that changes in DNA methylation associated with changes in μ-opioid expression were an order of magnitude greater than differences in brain. Hence, different degrees of DNA methylation associated with chronic opioid exposure are unlikely to exert a major role in the region-specificity of μ-opioid receptor expression in the human brain.

High variation of congener alcohols in apple wines

Congener alcohol (CA) analysis became an important tool in forensic science to prove the kind of alcoholic beverage consumed. The aim of the present study was to determine the influence of yeast strain and apple variety on the formation of congener alcohols in self-produced apple wine. There exist data on CA patterns of industrially produced alcoholic beverages, but these are not available for apple wine. Must from five different commercial as well as from six genuine apple varieties were used for fermentation under similar conditions CA formation was monitored during the fermentation process. Additionally, nine commercial apple wines from commercial producers were analyzed. Analysis was performed by headspaces-GC-MS. All apple wines contained markedly high contents of the CA 3-methylbutan-1-ol (88-251 mg/L). Compared to self-produced apple wines from genuine musts the industrial apple wines (purchased in supermarkets and self-produced from commercial musts) exhibited significant differences in methanol concentrations(8.5-94 mg/L), whereas all other CAs, such as propan-1-ol, butan-1-0l, 2-methylpropan-1-ol(isobutanol), 3-methyl-butan-1-oi, and 2-methylbutan-1-oi, were found to be present in similar concentrations. Methanol was not detectable in apple wine made from genuine musts during fermentation but after a storage period. In some cases, concentrations of some CAs additionally changed during storage. This may be explained by a secondary (unwanted) fermentation after bottling. According to the data obtained in the present study, it is recommended to analyze a sample of the allegedly consumed apple wine in forensic cases, rather than to rely on data obtained from the literature or from some data collections.

[How relevant is the risk of losing evidence due to delayed blood sampling? Conclusions from the evaluation of blood analysis results]

If the order of a judge to take a blood sample can only be obtained with a marked delay after the incident, evidence proving that a suspect had been driving under the influence of alcohol or drugs of abuse may be lost. The evaluation of blood analysis results from the Institute of Legal Medicine in Frankfurt/Main from the years 2012-2014 shows that in 1.6 to 11.6% of positive cases, the drug concentrations were near the legal limits (20.2% of alcohol-positive and 7.5% of illicit drugs-positive samples). A loss of evidence can thus be expected in a large number of cases when the time between the police check of a driver and the collection of a blood sample increases. Blood concentrations of alcohol and drugs of abuse, especially tetrahydrocannabinol, cocaine, methamphetamine, and morphine, may already have dropped significantly after a delay of only half an hour. These delays are typically due to the time elapsing until the order to take a blood sample has been obtained from a judge and a medical doctor becomes available and arrives at the police station to draw a blood sample. The recommendation of medicolegal experts is to keep the time between police check of a suspect and blood sampling as short as possible. In routine cases, a realistic maximum of one hour should not be exceeded.

Studies on the alkaloid composition of the Hawaiian Baby Woodrose Argyreia nervosa, a common legal high

Seeds from the Hawaiian Baby Woodrose Argyreia nervosa of different origin and labelling and with allegedly high levels of ergot alkaloids were analysed using high performance liquid chromatography-high resolution mass spectrometry (HPLC-HRMS/MS) technique. Lysergic acid amide (LSA), ergometrine, lysergol/elymoclavine/setoclavine, chanoclavine, lysergic acid and their respective stereoisomers were identified as well as penniclavine and lysergic acid α-hydroxyethylamide. In addition, methylergometrine, methysergide, and lysergylalanine were detected, some high molecular weight ergot alkaloid derivatives and hydroxyalanine derived ergopeptide fragments were detected indicating the presence of ergopeptides in the seeds. The results of the study demonstrate that the content of ergot alkaloids in Argyreia nervosa seeds depends on the quality of the material. For a consumer the quality of the seeds is unforeseeable. For the toxicological expert it is essential to investigate not only the identity of such a confiscated seed material, but also the various ergot alkaloid constituents to assess the hazardous nature and the toxic potential of the material.

Use of lidocaine in endotracheal intubation. Blood and urine concentrations in patients and deceased after unsuccessful resuscitation

In toxicological analysis of postmortem samples the local anesthetic lidocaine is often identified. In most cases, lidocaine levels result from its use as aid in endotracheal intubation. The range of the drug's concentration in blood and urine was studied under controlled conditions from a cohort of cardiac surgery patients (n=35). Plasma concentrations 1 h after exposure to lidocaine in the range of the recommended 81 mg coating the endotracheal tube were less than 0.2 mg/l, its metabolite monoethylglycinxylidide (MEGX) less than 0.05 mg/l (median ratio 0.18, range 0.03-1.23). Also the concentrations of lidocaine and MEGX in urine samples were low (less than 1.2 and 0.1 mg/l, respectively) with MEGX/lidocaine ratios of 0.11 (median, range up to 1.2). These data were compared with results obtained by analyzing postmortem blood and urine samples of 18 deceased with a documented cardiopulmonary resuscitation attempt prior to death. Blood concentrations were in the same range (lidocaine median 0.07, range 0.02-1.07 mg/l; MEGX median 0.01, range <0.001-0.044 mg/l); besides low lidocaine concentrations in urine. MEGX was detected only in 2 out of 9 urine samples. The results of the present study confirm that lidocaine is absorbed in the trachea from the endotracheal tube coated with lidocaine containing gel. Postmortem quantitative results can be explained on the basis of the data obtained in the controlled study.

Retrospective analysis of synthetic cannabinoids in serum samples--epidemiology and consumption patterns

Herbal mixtures contain synthetic cannabinoids, which can cause severe intoxications. Due to the great variety and the changing spectrum of substances on the drug market, prevalence data are limited, and data on prevalence rates of synthetic cannabinoids in forensic cases are not available. The present study was performed to survey the prevalence of synthetic cannabinoids in cases of traffic and criminal offences in the German state Hesse in 2010. The applied analytical method covered all synthetic cannabinoids on the drug market at that time, and with 20% of the blood samples (422 out of 2201) a representative number was reanalyzed. In twelve samples synthetic cannabinoids were identified and a prevalence of 2.8% was estimated. Consumption patterns showed predominantly cases of multi-drug consumption (10 cases); the combination with cannabis or alcohol was frequent (four cases each). The observed deficits were moderate with the exception of aggravation of paranoia in one case. The symptoms were either compatible with the effects of cannabinoid agonists or attributable to alcohol or other drugs found in the blood samples. Our current analytical strategy is to perform such analyses only in cases where use is suspected or where symptoms are not explained by routine toxicological analyses. Hence, the positive rate is rather low highlighting the need to keep up with the developments on the drug market and to establish sensitive screening methods covering a broad range of substances that can be updated fast, e.g., relying on collections of mass spectrometric reference data.

Sleep self-intoxication and sleep driving as rare zolpidem-induced complex behaviour

INTRODUCTION

The GABA(A) receptor agonist zolpidem has been used for treatment of insomnia since years, but special side effects have been reported. These side effects were called zolpidem-induced sleep-related complex behaviour. Such complex behaviour is associated with somnambulism and includes sleepwalking, sleep eating, sleep conversation and sleep driving.

CASE PRESENTATION

Two cases of zolpidem-induced sleep-related complex behaviour following self-intoxication, sleep driving and amnesia are presented. In both cases, the subjects reported the voluntary intake of only one zolpidem tablet of 10 mg and amnesia for the time afterwards. Shortly after the onset of the drug's action, both individuals drifted into a somnambulism-like state and toxicological blood analysis suggested the intake of the remaining zolpidem tablets which might be called "sleep intoxication". Later, the subjects were arrested by police after driving under drug influence and not realizing the situation. Retrospectively, both subjects suffered from psychiatric disorders and in case 2, the subject was treated for depression with doxepin. Consequently, these co-factors may have increased the risk for the occurrence of the sleep-related complex behaviour.

DISCUSSION

Involuntary self-intoxication should be taken into account in addition to the known pattern of zolpidem-induced complex behaviour. In legal cases, the forensic expert has to assess the blood concentration of zolpidem in evaluating this strange behaviour.

CONCLUSION

Amnesia and incoherence of speech, disorganization of behaviour, inability to realize the situation and mood changes may indicate a zolpidem-induced somnambulism-like state with sleep-related complex behaviour.

[Trauma centre admission of severely injured or critically ill patients: comparison of estimated and real arrival times]

BACKGROUND

During early in-hospital management of the arriving trauma patient the timing of the trauma team alert is an important organisational step. To evaluate the accordance of the estimated and the real arriving time we performed a retrospective data analysis at a level I German trauma centre.

METHODS

Retrospective data analysis. Trauma team alerts from September 2010 until March 2011 were analysed. According to the hospitals pre-alert algorithm, trauma team alert took place 10 min before the estimated time of arrival.

RESULTS

There were 165 trauma team alerts included in the analysis. The estimated arrival time coincided with the real arrival time in less than 10 % of cases. In 76 % of the cases, the patient arrived in an acceptable time frame with the trauma team waiting less than 14 min. In 3 % of the cases, the patient arrived prior to the trauma team.

CONCLUSION

An exact estimation of the arrival time is rare. With a trauma team alert 10 min prior to the estimated time of arrival, an acceptable waiting time can be achieved. Arrival of the patient prior to the trauma team can be avoided.

Chemical camouflage--a frog's strategy to co-exist with aggressive ants

Whereas interspecific associations receive considerable attention in evolutionary, behavioural and ecological literature, the proximate bases for these associations are usually unknown. This in particular applies to associations between vertebrates with invertebrates. The West-African savanna frog Phrynomantis microps lives in the underground nest of ponerine ants (Paltothyreus tarsatus). The ants usually react highly aggressively when disturbed by fiercely stinging, but the frog is not attacked and lives unharmed among the ants. Herein we examined the proximate mechanisms for this unusual association. Experiments with termites and mealworms covered with the skin secretion of the frog revealed that specific chemical compounds seem to prevent the ants from stinging. By HPLC-fractionation of an aqueous solution of the frogs' skin secretion, two peptides of 1,029 and 1,143 Da were isolated and found to inhibit the aggressive behaviour of the ants. By de novo sequencing using tandem mass spectrometry, the amino acid sequence of both peptides consisting of a chain of 9 and 11 residues, respectively, was elucidated. Both peptides were synthesized and tested, and exhibited the same inhibitory properties as the original frog secretions. These novel peptides most likely act as an appeasement allomone and may serve as models for taming insect aggression.

Argyreia nervosa (Burm. f.): receptor profiling of lysergic acid amide and other potential psychedelic LSD-like compounds by computational and binding assay approaches

ETHNOPHARMACOLOGICAL RELEVANCE

The convolvulacea Argyreia nervosa (Burm. f.) is well known as an important medical plant in the traditional Ayurvedic system of medicine and it is used in numerous diseases (e.g. nervousness, bronchitis, tuberculosis, arthritis, and diabetes). Additionally, in the Indian state of Assam and in other regions Argyreia nervosa is part of the traditional tribal medicine (e.g. the Santali people, the Lodhas, and others). In the western hemisphere, Argyreia nervosa has been brought in attention as so called "legal high". In this context, the seeds are used as source of the psychoactive ergotalkaloid lysergic acid amide (LSA), which is considered as the main active ingredient.

AIM OF THE STUDY

As the chemical structure of LSA is very similar to that of lysergic acid diethylamide (LSD), the seeds of Argyreia nervosa (Burm. f.) are often considered as natural substitute of LSD. In the present study, LSA and LSD have been compared concerning their potential pharmacological profiles based on the receptor binding affinities since our recent human study with four volunteers on p.o. application of Argyreia nervosa seeds has led to some ambiguous effects.

MATERIAL AND METHODS

In an initial step computer-aided in silico prediction models on receptor binding were employed to screen for serotonin, norepinephrine, dopamine, muscarine, and histamine receptor subtypes as potential targets for LSA. In addition, this screening was extended to accompany ergotalkaloids of Argyreia nervosa (Burm. f.). In a verification step, selected LSA screening results were confirmed by in vitro binding assays with some extensions to LSD.

RESULTS

In the in silico model LSA exhibited the highest affinity with a pKi of about 8.0 at α1A, and α1B. Clear affinity with pKi>7 was predicted for 5-HT1A, 5-HT1B, 5-HT1D, 5-HT6, 5-HT7, and D2. From these receptors the 5-HT1D subtype exhibited the highest pKi with 7.98 in the prediction model. From the other ergotalkaloids, agroclavine and festuclavine also seemed to be highly affine to the 5-HT1D-receptor with pKi>8. In general, the ergotalkaloids of Argyreia nervosa seem to prefer serotonin and dopamine receptors (pKi>7). However, with exception of ergometrine/ergometrinine only for 5-HT3A, and histamine H2 and H4 no affinities were predicted. Compared to LSD, LSA exhibited lower binding affinities in the in vitro binding assays for all tested receptor subtypes. However, with a pKi of 7.99, 7.56, and 7.21 a clear affinity for 5-HT1A, 5-HT2, and α2 could be demonstrated. For DA receptor subtypes and the α1-receptor the pKi ranged from 6.05 to 6.85.

CONCLUSION

Since the psychedelic activity of LSA in the recent human study was weak and although LSA from Argyreia nervosa is often considered as natural exchange for LSD, LSA should not be regarded as LSD-like psychedelic drug. However, vegetative side effects and psychotropic effects may be triggered by serotonin or dopamine receptor subtypes.

Venomous secretions from marine snails of the Terebridae family target acetylcholine receptors

Venoms from cone snails (Conidae) have been extensively studied during the last decades, but those from other members of the suborder Toxoglossa, such as of Terebridae and Turridae superfamilies attracted less interest so far. Here, we report the effects of venom and gland extracts from three species of the superfamily Terebridae. By 2-electrode voltage-clamp technique the gland extracts were tested on Xenopus oocytes expressing nicotinic acetylcholine receptors (nAChRs) of rat neuronal (α3β2, α3β4, α4β2, α4β4, α7) and muscle subtypes (α1β1γδ), and expressing potassium (Kv1.2 and Kv1.3) and sodium channels (Nav1.2, 1.3, 1.4, 1.6). The extracts were shown to exhibit remarkably high inhibitory activities on almost all nAChRs tested, in particular on the α7 subtype suggesting the presence of peptides of the A-superfamily from the venom of Conus species. In contrast, no effects on the potassium and sodium channels tested were observed. The venoms of terebrid snails may offer an additional source of novel biologically active peptides.

Influence of ethanol on the pharmacokinetic properties of Δ9-tetrahydrocannabinol in oral fluid

Oral fluid (OF) tests aid in identifying drivers under the influence of drugs. In this study, 17 heavy cannabis users consumed alcohol to achieve steady blood alcohol concentrations of 0 to 0.7 g/L and smoked cannabis 3 h afterward. OF samples were obtained before and up to 4 h after smoking and on-site tests were performed (Dräger DrugTest 5000 and Securetec DrugWipe 5+). Maximum concentrations of tetrahydrocannabinol (THC) immediately after smoking (up to 44,412 ng/g) were below 4,300 (median 377) ng/g 1 h after smoking and less than 312 (median 88) ng/g 3 h later with 5 of 49 samples negative, suggesting that recent cannabis use might occasionally not be detectable. An influence of alcohol was not observed. Drinking 300 mL variably influenced THC concentrations (median only -29.6%), which suggests that drinking does not markedly affect on-site test performance. Many (92%) Dräger tests performed 4 h after smoking were still positive, indicating sufficient sensitivity for recent cannabis use. Differences in the results of a roadside study with DrugTest 5000 (sensitivity 84.8%, specificity 96.0%, accuracy 84.3%) could be explained by a higher number of true negatives, differences between OF and serum and differences between occasional and chronic users.

Altered gene expression in the prefrontal cortex of young rats induced by the ADHD drug atomoxetine

Atomoxetine (ATX), a selective norepinephrine reuptake inhibitor, is a non-stimulant approved for the treatment of attention deficit/hyperactivity disorder (ADHD). Little is known about the molecular basis for its therapeutic effect. The objective of this animal study was to determine alterations in gene expression patterns in the prefrontal cortex after long-term administration of atomoxetine. Rats were treated for 21 days during childhood and early adolescent stages of development with a once-daily oral application of 0.05 g/kg atomoxetine, which resulted in plasma levels similar to those described in children. A whole genome RNA-microarray of rat prefrontal cortical gene expression after administration of atomoxetine versus sterile water revealed an mRNA increase in 114 genes (≥2-fold) while 11 genes were down-regulated (≤0.5-fold). By applying quantitative real-time PCR (qRT-PCR) and Western Blot we confirmed a significant increase in the expression of GABA A receptor subunits as well as ubiquinol-cytochrome c reductase complex core protein 2 (Uqcrc2). SNAP-25 (synaptosomal-associated protein of 25 kDa), which is an ADHD candidate gene and an important vesicle protein involved in axonal growth, synaptic plasticity and regulation of neurotransmitter release was also significantly upregulated on RNA- and protein level after atomoxetine treatment. In summary, we could show that long-term treatment with the ADHD drug atomoxetine induces the regulation of several genes in the prefrontal cortex of young rats. Especially the increased expression of SNAP-25 and GABA-A receptor subunits may indicate additional active therapeutic mechanisms for atomoxetine.

Early repair of open abdomen with a tailored two-component mesh and conditioning vacuum packing: a safe alternative to the planned giant ventral hernia

Purpose

Once open abdomen therapy has succeeded, the problem of closing the abdominal wall must be addressed. We present a new four-stage procedure involving the application of a two-component mesh and vacuum conditioning for abdominal wall closure of even large defects. The aim is to prevent the development of a giant ventral hernia and the eventual need for the repair of the abdominal wall.

Methods

Nineteen of 62 patients treated by open abdomen over a two-year period could not receive primary abdominal wall closure. To achieve closure in these patients, we applied the following four-stage procedure: stage 1: abdominal damage control and conditioning of the abdominal wall; stage 2: attachment of a tailored two-component mesh of polyglycolic acid (PGA) and large pore polypropylene (PP) in intraperitoneal position (IPOM) plus placement of a vacuum bandage; stage 3: vacuum therapy for 3–4 weeks to allow granulation of the mesh and optimization of dermatotraction; stage 4: final skin suture. During stage 3, eligible patients were weaned from respirator and mobilized.

Results

The abdominal wall gap in the 19 patients ranged in size from 240 cm² to more than 900 cm². An average of 3.44 vacuum dressing changes over 19 days were required to achieve 60–100 % granulation of the surface area, so final skin suture could be made. Already in stage 3, 14 patients (73.68 %) could be weaned from respirator an average of 6.78 days after placement of the two-component mesh; 6 patients (31.57 %) could be mobilized on the edge of the bed and/or to a bedside chair after an average of 13 days. No mesh-related hematomas, seromas, or intestinal fistulas were observed.

Conclusion

The four-stage procedure presented here is a viable option for achieving abdominal wall closure in patients treated with open abdomen, enabling us to avoid the development of planned giant ventral hernias. It has few complications and has the special advantage of allowing mobilization of the patients before final skin closure. Long-term course in a large number of patients must still confirm this result.

Variable adverse effects in subjects after ingestion of equal doses of Argyreia nervosa seeds

As the new drug Spice hit the market in 2006 and was a hot topic in the media, the general issue of legal highs has been brought to the attention of a large number of (young) people. One of these so called legal highs are the seeds of Argyreia nervosa, also known as Hawaiian Baby Woodrose, which contains the psychotropic alkaloid lysergic acid amide (LSA). A study was designed to assess how driving ability is affected by Argyreia nervosa. However, the study could not be continued due to severe adverse effects in 3 of 4 subjects, such as cardiovascular dysregulation in two and a psychosis like state in one subject. All of the participants recovered completely within 9h after ingestion. Despite body normalized doses interindividually highly differing reactions in type and intensity were observed. Furthermore, fluctuating alkaloid contents in seeds and multi-drug intoxications make the use of this legal high far more dangerous than commonly believed.

Influence of ethanol on cannabinoid pharmacokinetic parameters in chronic users

Cannabis is not only the most widely used illicit drug worldwide but is also regularly consumed along with ethanol. In previous studies, it was assumed that cannabis users develop cross-tolerance to ethanol effects. The present study was designed to compare the effects of ethanol in comparison to and in combination with a cannabis joint and investigate changes in pharmacokinetics. In this study, 19 heavy cannabis users participated and received three alcohol dosing conditions that were calculated to achieve steady blood alcohol concentrations (BAC) of about 0, 0.5 and 0.7 g/l during a 5-h time window. Subjects smoked a Δ(9)-tetrahydrocannabinol (THC) cigarette (400 μg/kg) 3 h post-onset of alcohol dosing. Blood samples were taken between 0 and 4 h after smoking. During the first hour, samples were collected every 15 min and every 30 min thereafter. Mean steady-state BACs reached 0, 0.36 and 0.5 g/l. The apparent elimination half-life of THC was slightly prolonged (1.59 vs. 1.93 h, p < 0.05) and the concentration 1 h after smoking was slightly lower (24 vs. 17 ng/ml, p < 0.05) with the higher ethanol dose. The prolonged THC elimination might be explained by a small ethanol-mediated change in distribution to and from deep compartments. Concentrations and pharmacokinetics of 11-hydroxy-THC and 11-nor-9-carboxy-THC (THCA) were not significantly influenced by ethanol. However, THCA concentrations appeared lower in both ethanol conditions, which might also be attributable to changes in distribution. Though not significant in the present study, this might be relevant in the interpretation of cannabinoid concentrations in blood.

Hepatic effects of an open lung strategy and cardiac output restoration in an experimental lung injury

BACKGROUND

Ventilation with high positive end-expiratory pressure (PEEP) can lead to liver dysfunction. We hypothesized that an open lung concept (OLC) using high PEEP impairs liver function and integrity dependent on the stabilization of cardiac output.

METHODS

Juvenile female Pietrain pigs instrumented with flow probes around the common hepatic artery and portal vein, pulmonary and hepatic vein catheters underwent a lavage-induced lung injury. Ventilation was continued with a conventional approach (CON) using pre-defined combinations of PEEP and inspiratory oxygen fraction or with an OLC using PEEP set above the lower inflection point of the lung. Volume replacement with colloids was guided to maintain cardiac output in the CON(V+) and OLC(V+) groups or acceptable blood pressure and heart rate in the OLC(V-) group. Indocyanine green plasma disappearance rate (ICG-PDR), blood gases, liver-specific serum enzymes, bilirubin, hyaluronic acid and lactate were tested. Finally, liver tissue was examined for neutrophil accumulation, TUNEL staining, caspase-3 activity and heat shock protein 70 mRNA expression.

RESULTS

Hepatic venous oxygen saturation was reduced to 18 + or - 16% in the OLC(V-) group, while portal venous blood flow decreased by 45%. ICG-PDR was not reduced and serum enzymes, bilirubin and lactate were not elevated. Liver cell apoptosis was negligible. Liver sinusoids in the OLC(V+) and OLC(V-) groups showed about two- and fourfold more granulocytes than the CON(V+) group. Heat shock protein 70 tended to be higher in the OLC(V-) group.

CONCLUSIONS

Open lung ventilation elicited neutrophil infiltration, but no liver dysfunction even without the stabilization of cardiac output.

[Interpretation of blood analysis data found after passive exposure to cannabis]

When defendants are confronted with evidence of cannabinoids in their blood suggesting consumption of cannabis they sometimes argue that this could only be due to a passive exposure. The small number of controlled studies available showed that tetrahydrocannabinol (THC), the active ingredient of cannabis, was actually found in the blood after passive exposure to cannabis smoke. The resulting blood concentrations were dependent on the applied THC doses and the size of the room in which the passive exposure occurred. However, the quantitative data indicated in the publications of the 1980s cannot be fully compared with the results of modern analytical methods. Due to the rapid distribution of THC in the body, which occurs also after passive exposure to low doses, the THC concentration in serum to be expected in a blood sample taken 1 hour after exposure is less than 1 ng/mL. For assessment of an alleged passive exposure, the metabolic THC-carboxylic acid, which is excreted more slowly, must also be taken into account. After passive exposure, similar and very low serum concentrations of THC and THC-carboxylic acid are to be expected (< 2 ng/mL), while higher blood levels suggest the deliberate consumption of a psychoactive dose.

New conopeptides of the D-superfamily selectively inhibiting neuronal nicotinic acetylcholine receptors

The venom of cone snails (Conus spp.) is a rich source of peptides exhibiting a wide variety of biological activities. Several of these conopeptides are neuronal nicotinic acetylcholine receptor (nAChR) antagonists and belong to the A-, M-, S-, C and the recently described D-superfamily (alphaD-conopeptides). Here we describe the discovery and characterization of two alphaD-conopeptides isolated from the venom of Conus mustelinus and Conus capitaneus. Their primary structure was determined by Edman degradation, MS/MS analysis and by a PCR based approach. These peptides show close structural homology to the alphaD-VxXIIA, -B and -C conopeptides from the venom of Conus vexillum and are dimers (about 11kDa) of similar or identical peptides with 49 amino acid residues and a characteristic arrangement of ten conserved cysteine residues. These novel types of conopeptides specifically block neuronal nAChRs of the alpha7, alpha3beta2 and alpha4beta2 subtypes in nanomolar concentrations. Due to their high affinity, these new ligands may provide a tool to decipher the localisation and function of the various neuronal nAChRs.