Can a threshold for 11‐nor‐9‐carboxy‐Δ9 ‐tetrahydrocannabinol in hair be derived when its respective concentration in blood serum indicates regular use?

A 100 μg/L or higher concentration of 11‐nor‐9‐carboxy‐Δ9‐tetrahydrocannabinol (THC‐COOH) in blood serum is generally assumed to be associated with regular and/or heavy use of cannabis. At present, determination of the extent of cannabis use by means of the concentration of THC‐COOH in hair has not been assessed. Therefore, we aimed at establishing a threshold for THC‐COOH concentrations in hair to prove frequent consumption by comparing THC‐COOH concentrations in 129 corresponding serum and hair samples, respectively. The concentration of THC‐COOH in the serum was analyzed by gas chromatography–mass spectrometry and in the hair by liquid chromatography–tandem mass spectrometry. Data were statistically evaluated using receiver operating characteristic curves and contingency tables. Our results suggest that a THC‐COOH concentration of ≥4.2 pg/mg in hair was always accompanied by a THC‐COOH concentration of at least 100 μg/L in blood serum. Should this be confirmed by further studies of a larger study population, a hair concentration of 4.2 pg/mg THC‐COOH can be set as a threshold to predict regular and/or heavy consumption of cannabis even if no corresponding blood sample is available for analysis.     

Unexpected results found in larvae samples from two postmortem forensic cases

Forensic Toxicology - In forensics, entomological specimens can be used as additional/alternative matrices to detect xenobiotics when human specimens are limited in their application. Despite some...     

Comparison of concentrations of drugs between blood samples with and without fluoride additive—important findings for Δ9-tetrahydrocannabinol and amphetamine

International Journal of Legal Medicine - Fluoride is a common stabilizing agent in forensic toxicology to avoid the frequent problem of degradation of drugs in blood samples especially described...     

Inward currents elicited by stream of fluid during transmitter-induced current oscillations in RNA-injected oocytes of Xenopus laevis.

A stream of fluid elicited an inward current in RNA-injected oocytes of Xenopus laevis during transmitter-induced current oscillations (stream evoked inward current, Ii,st). The Ii,st showed the following characteristics: (1) amplitude and duration (half width time) ranged between 10 and 300 nA and 1 and 3 s, respectively. (2) The Ii,st could be evoked only during transmitter-induced current oscillations; with blockade of the oscillations the Ii,st disappeared. (3) The induction of the Ii,st was independent of the composition of the washing fluid.     

Facilitation of learning by social-emotional feedback in humans is beta-noradrenergic-dependent

Adaptive behavior in dynamic environments critically depends on the ability to learn rapidly and flexibly from the outcomes of prior choices. In social environments, facial expressions of emotion often serve as performance feedback and thereby guide declarative learning. Abundant evidence implicates beta-noradrenergic signaling in the modulatory influence of emotion on declarative learning. It is currently unclear whether a similar mechanism also mediates a guidance of declarative learning by social-emotional feedback administered in the form of facial expressions. We therefore conducted a double-blind randomized placebo-controlled trial to test the effects of a 40-mg single oral dose of the nonspecific beta-noradrenergic antagonist propranolol in a behavioral task that required gradual declarative learning of item-category associations from either social-emotional (happy vs. angry faces) or nonsocial (green vs. red color signals) trial-by-trial feedback. As predicted on the basis of our previous experiments, learning from social-emotional feedback was more effective than learning from nonsocial feedback in placebo-treated subjects. This advantage of social-emotional over nonsocial feedback was abolished by propranolol treatment. Propranolol had no effect on learning during the nonsocial feedback condition. Our findings suggest that a facilitation of declarative learning by social-emotional feedback critically involves signaling via beta-noradrenergic receptors.