Reversibility of the acute toxic effect of Cyclosporin A on pancreatic B cells of Wistar rats

Summary. This study investigated if and to what extent the acute toxic effect of Cyclosporin A on pancreatic Wistar rat B cells is reversible. After 2 weeks of treatment rats developed marked glucose intolerance accompanied by reduced pancreatic insulin content due to a loss of B cells, diminished islet DNA synthesis and decreased B-cell insulin content. Cyclosporin A had accumulated in the pancreas. Three weeks after withdrawal of Cyclosporin A, pancreatic tissue concentrations of Cyclosporin A were still 100 times larger than in serum. Glucose tolerance, however, had already improved, associated with an increase of B-cell insulin content and apparent islet replication, and the insulin response of isolated islets was reduced. Five weeks after the withdrawal of Cyclosporin A, glucose tolerance was normal, but pancreatic insulin content and relative B-cell volume were still diminished in comparison to vehicle-treated controls. Eight weeks after withdrawal, the morphometric parameters had also been normalized. The results suggest that the loss of pancreatic B cells is caused by a toxic destruction, possibly combined with an apparent decrease of replicatory activity. The acute toxic effects of Cyclosporin A in pancreatic B cells are stepwise reversible.     

Off-label-dosing of non-vitamin K-dependent oral antagonists in AF patients before and after stroke: results of the prospective multicenter Berlin Atrial Fibrillation Registry

Aims

We aimed to analyze prevalence and predictors of NOAC off-label under-dosing in AF patients before and after the index stroke.

Methods

The post hoc analysis included 1080 patients of the investigator-initiated, multicenter prospective Berlin Atrial Fibrillation Registry, designed to analyze medical stroke prevention in AF patients after acute ischemic stroke.

Results

At stroke onset, an off-label daily dose was prescribed in 61 (25.5%) of 239 NOAC patients with known AF and CHA₂DS₂-VASc score ≥ 1, of which 52 (21.8%) patients were under-dosed. Under-dosing was associated with age ≥ 80 years in patients on rivaroxaban [OR 2.90, 95% CI 1.05–7.9, P = 0.04; n = 29] or apixaban [OR 3.24, 95% CI 1.04–10.1, P = 0.04; n = 22]. At hospital discharge after the index stroke, NOAC off-label dose on admission was continued in 30 (49.2%) of 61 patients. Overall, 79 (13.7%) of 708 patients prescribed a NOAC at hospital discharge received an off-label dose, of whom 75 (10.6%) patients were under-dosed. Rivaroxaban under-dosing at discharge was associated with age ≥ 80 years [OR 3.49, 95% CI 1.24–9.84, P = 0.02; n = 19]; apixaban under-dosing with body weight ≤ 60 kg [OR 0.06, 95% CI 0.01–0.47, P < 0.01; n = 56], CHA₂DS₂-VASc score [OR per point 1.47, 95% CI 1.08–2.00, P = 0.01], and HAS-BLED score [OR per point 1.91, 95% CI 1.28–2.84, P < 0.01].

Conclusion

At stroke onset, off-label dosing was present in one out of four, and under-dosing in one out of five NOAC patients. Under-dosing of rivaroxaban or apixaban was related to old age. In-hospital treatment after stroke reduced off-label NOAC dosing, but one out of ten NOAC patients was under-dosed at discharge.

Clinical trial registration

NCT02306824.

     

Studies on in vitro degradation of anhydroecgonine methyl ester (methylecgonidine) in human plasma

The presence of the cocaine pyrolysis product anhydroecgonine methyl ester (AEME, methylecgonidine) in plasma indicates the smoking of cocaine. The stability of this analyte in human plasma has not been studied. In the present investigation AEME and its hydrolysis product anhydroecgonine (AE, ecgonidine) were assayed in plasma and buffers using gas chromatography-mass spectrometry. It was found that 50% of AEME in human plasma was hydrolyzed to AE within 5 days at room temperature and within 13 days at 4 degrees C. Addition of esterase inhibitors such as sodium fluoride or echothiophate iodide reduced the hydrolysis significantly. Hydrolysis of AEME also occurred in buffers with pH values above 5, but the hydrolysis rate was significantly lower when compared with plasma and could be markedly increased by the addition of butyrylcholine esterase. The data suggest that AEME is degraded via two mechanisms: chemical hydrolysis at basic pH and enzymatic hydrolysis by butyrylcholine esterase. Therefore, proper storage conditions must be provided for the assay of AEME in plasma.     

Studies on hydrolytic and oxidative metabolic pathways of anhydroecgonine methyl ester (methylecgonidine) using microsomal preparations from rat organs

During smoking of cocaine-base (crack), anhydroecgonine methyl ester (AEME, methylecgonidine) is formed in large amounts as a pyrolysis product of cocaine and is absorbed in the lungs. The metabolism of AEME was studied in the present investigation using microsome preparations from rat liver, lung, kidney, and brain. Potential metabolites of AEME were synthesized and used as substrate to complement the experiments. Analysis of the incubation mixtures was performed using gas chromatography-mass spectrometry and nanoelectrospray multiple-stage mass spectrometry. Screening for metabolites was focused on postulated oxidative pathways, chemical and enzymatic hydrolysis, and ethanol dependent transesterification as known from cocaine metabolism. Enzymatic hydrolysis of AEME to anhydroecgonine (AE), which was inhibited by sodium fluoride, was found in all microsomal preparations. Liver microsomes exhibited the highest activity, brain microsomes the lowest. Anhydronorecgonine methyl ester (ANEME) and anhydroecgonine methyl ester N-oxide were identified as AEME metabolites of liver and lung microsomes only. In the presence of ethanol AEME was metabolized to anhydroecgonine ethyl ester and anhydronorecgonine ethyl ester. Further metabolism of AE or ANEME was not observed. No N-hydroxy-anhydronorecgonine derivatives were found which could represent precursors of cytotoxic metabolites as known to be formed from cocaine.     

Screening for drugs of abuse in oral fluid--correlation of analysis results with serum in forensic cases

The testing of saliva or oral fluid at the roadside could be a powerful tool to detect drivers under the influence of drugs and has several advantages over urine screening. In 177 cases of individuals suspected of driving under the influence of drugs, oral fluid was collected at the roadside and analyzed in parallel to serum samples. The study was performed to investigate the variability of oral fluid analysis results in relation to blood/serum. In 45% of the cases single-drug use was found, and in 50% poly-drug use was found. Cannabis was most prevalent (78%), and 70% of these individuals were also positive for tetrahydrocannabinol in serum. Overall, 97% of oral fluid samples positive for any substance were also positive in serum. Comparing data of oral fluid and serum for amphetamine, MDMA, morphine, benzoylecgonine, and tetrahydrocannabinol, the sensitivities were 100%, 97%, 87%, 87%, and 92%, respectively. Overall specificity and accuracy were in the range of 91-98%. Discrepancies between a negative oral fluid sample and a positive serum sample could be explained by analytical insensitivity in the lower volume of oral fluid analyzed (estimated for 0.1 mL confirmation vs. 1 mL of serum) or a shorter detection window in oral fluid. The low prevalence of discrepancies with positive oral fluid and negative serum results (2-9% of the cases) may be explained by persistent oral contamination especially for orally consumed drugs, like MDMA and cannabis. It is concluded that the detection of a psychoactive substance in oral fluid taken at the roadside is highly predictive for the detection of the corresponding drug or its metabolite in serum. Oral fluid testing is therefore suitable for the efficient confirmation of drug use of drivers suspected of being under the influence of drugs.     

Dynamic spin labeling angiography in extracranial carotid artery stenosis

BACKGROUND AND PURPOSE: Similar to digital subtraction angiography, dynamic spin labeling angiography (DSLA) provides time-resolved measurements of the influx of blood into the cerebral vascular tree. We determined whether DSLA may help in assessing the degree of stenosis and whether it provides information about intracerebral collateralization and allows us to monitor the hemodynamic effects of vascular interventions. METHODS: We developed a segmented DSLA sequence that allowed the formation of images representing inflow delays in 41-ms increments. Thirty patients with unilateral carotid artery stenosis and 10 control subjects underwent DSLA. Arrival times of the labeled arterial blood bolus were measured in the carotid siphon (CS) and the middle cerebral artery (MCA) on both sides, and the corresponding side-to-side arrival time differences (ATDs) were calculated. ATDs before and after carotid endarterectomy or percutaneous angioplasty were studied in 10 patients. RESULTS: The degree of stenosis was significantly correlated with ATD in the cerebral vessels. Receiver operating characteristic analysis yielded a cutoff CS ATD of 110 ms to separate stenoses <70% from those > or =70%, with a sensitivity of 90% and a specificity of 67%. In one third of patients, ATD was higher in the MCA than in the CS; this finding suggested an absence of collateralization. Most patients had reduced ATD in the MCA. The degree of ATD reduction was regarded as a quantitative measure of collateralization. Successful intervention resulted in normalized ATDs. CONCLUSION: DSLA is a promising method that allowed us to noninvasively quantify the hemodynamic effect of extracranial carotid stenosis and the resulting intracranial collateralization.     

A new quantitative method for pivot shift grading

Purpose  

The purposes of the study were to evaluate and to quantify the pivot shift phenomenon by using a small and easy to handle measuring device for pivot shift quantification.     

Cognition and motor control as a function of Delta9-THC concentration in serum and oral fluid: limits of impairment

Cannabis use has been associated with increased risk of becoming involved in traffic accidents; however, the relation between THC concentration and driver impairment is relatively obscure. The present study was designed to define performance impairment as a function of THC in serum and oral fluid in order to provide a scientific framework to the development of per se limits for driving under the influence of cannabis. Twenty recreational users of cannabis participated in a double-blind, placebo-controlled, three-way cross-over study. Subjects were administered single doses of 0, 250 and 500 microg/kg THC by smoking. Performance tests measuring skills related to driving were conducted at regular intervals between 15 min and 6h post smoking and included measures of perceptual-motor control (Critical tracking task), motor impulsivity (Stop signal task) and cognitive function (Tower of London). Blood and oral fluid were collected throughout testing. Results showed a strong and linear relation between THC in serum and oral fluid. Linear relations between magnitude of performance impairment and THC in oral fluid and serum, however, were low. A more promising way to define threshold levels of impairment was found by comparing the proportion of observations showing impairment or no impairment as a function of THC concentration. The proportion of observations showing impairment progressively increased as a function of serum THC in every task. Binomial tests showed an initial and significant shift toward impairment in the Critical tracking task for serum THC concentrations between 2 and 5 ng/ml. At concentrations between 5 and 10 ng/ml approximately 75-90% of the observations were indicative of significant impairment in every performance test. At THC concentrations >30 ng/ml the proportion of observations indicative of significant impairment increased to a full 100% in every performance tests. It is concluded that serum THC concentrations between 2 and 5 ng/ml establish the lower and upper range of a THC limit for impairment.