Effects of a fungicide (imazalil) and an insecticide (diazinon) on stream fungi and invertebrates associated with litter breakdown

The intensification of agriculture has promoted the use of pesticides such as fungicides and insecticides. Many pesticides readily leach into natural water bodies and affect both organisms and ecosystem processes such as leaf breakdown, a crucial process in headwater streams. As leaf breakdown in streams involves sequential steps by different groups of organisms (first microbial conditioning, then invertebrate shredding), pesticides targeting different organisms are likely to affect one or the other step, and a mixture of contaminants might have interactive effects. Our objective was to evaluate the effect of a fungicide (imazalil) and an insecticide (diazinon) on stream fungal and invertebrate activities, and their effects on leaf consumption. After an initial assay to define 'effective concentration' of both pesticides in a laboratory experiment, we manipulated pesticide presence/absence during the conditioning and shredding phases. Both pesticides affected fungal community and reduced the performance of the shredding amphipod Echinogammarus berilloni, and leaf consumption. The impact of pesticides on fungal sporulation depended on the length of the exposure period. In addition, pesticides seemed to cause an energetic imbalance in the amphipod, affecting body condition and mortality. The combined effect of both pesticides was similar to those of the fungicide. Overall, our results show that the effects of pesticide mixtures on leaf breakdown are hard to predict from those observed in either fungi or macroinvertebrate performance.

Analysis of ECs and related compounds in plasma: artifactual isomerization and ex vivo enzymatic generation of 2-MGs

The analysis of peripheral endocannabinoids (ECs) is a good biomarker of the EC system. Their concentrations, from clinical studies, strongly depend on sample collection and time processing conditions taking place in clinical and laboratory settings. The analysis of 2-monoacylglycerols (MGs) (i.e., 2-arachidonoylglycerol or 2-oleoylglycerol) is a particularly challenging issue because of their ex vivo formation and chemical isomerization that occur after blood sample collection. We provide evidence that their ex vivo formation can be minimized by adding Orlistat, an enzymatic lipase inhibitor, to plasma. Taking into consideration the low cost of Orlistat, we recommend its addition to plasma collecting tubes while maintaining sample cold chain until storage. We have validated a method for the determination of the EC profile of a range of MGs and N-acylethanolamides in plasma that preserves the original isomer ratio of MGs. Nevertheless, the chemical isomerization of 2-MGs can only be avoided by an immediate processing and analysis of samples due to their instability during conservation. We believe that this new methodology can aid in the harmonization of the measurement of ECs and related compounds in clinical samples.

Functional alteration in frontolimbic systems relevant to moral judgment in cocaine-dependent subjects

Cocaine addiction is characterized by persistent decision-making deficits, which are linked to structural and functional abnormalities in frontolimbic systems. Moral judgment is as a special instance of decision making, in which both cognitive and emotional signals must be adequately integrated to decide how to resolve moral dilemmas. Here, we employed a moral dilemmas functional magnetic resonance imaging (fMRI) task to explore possible alterations of frontolimbic systems in cocaine-dependent subjects. We also explored if these alterations relate to more basic deficits in functional connectivity within these systems during spontaneous resting-state activation. Ten cocaine-dependent subjects and 14 non-drug-using controls participated in the study. Cocaine-dependent subjects were carefully selected to discard potentially confounding co-morbidities, and they underwent a uniform supervised abstinence period of 10 days. Both groups were scanned, and fMRI maps were generated to identify (1) brain response to moral dilemmas; and (2) the strength of functional connectivity within frontolimbic systems during resting-state. During the moral dilemmas task, cocaine-dependent subjects showed reduced activation involving frontolimbic structures as the anterior cingulate cortex (ACC), left insula and brain stem. Connectivity analyses showed that cocaine users had less resting-state functional connectivity between ACC, thalamus, insula and brain stem. These results demonstrate that cocaine-dependent subjects have functional alterations in the frontolimbic systems that support moral judgment and social decision making.

Epigallocatechin-3-gallate, a DYRK1A inhibitor, rescues cognitive deficits in Down syndrome mouse models and in humans

SCOPE

Trisomy for human chromosome 21 results in Down syndrome (DS), which is among the most complex genetic perturbations leading to intellectual disability. Accumulating data suggest that overexpression of the dual-specificity tyrosine-(Y)-phosphorylation regulated kinase 1A (DYRK1A), is a critical pathogenic mechanisms in the intellectual deficit.

METHODS AND RESULTS

Here we show that the green tea flavonol epigallocatechin-gallate (EGCG), a DYRK1A inhibitor, rescues the cognitive deficits of both segmental trisomy 16 (Ts65Dn) and transgenic mice overexpressing Dyrk1A in a trisomic or disomic genetic background, respectively. It also significantly reverses cognitive deficits in a pilot study in DS individuals with effects on memory recognition, working memory and quality of life. We used the mouse models to ensure that EGCG was able to reduce DYRK1A kinase activity in the hippocampus and found that it also induced significant changes in plasma homocysteine levels, which were correlated with Dyrk1A expression levels. Thus, we could use plasma homocysteine levels as an efficacy biomarker in our human study.

CONCLUSION

We conclude that EGCG is a promising therapeutic tool for cognitive enhancement in DS, and its efficacy may depend of Dyrk1A inhibition.

Functional effects of chronic paroxetine versus placebo on the fear, stress and anxiety brain circuit in Social Anxiety Disorder: initial validation of an imaging protocol for drug discovery

Recent studies suggest that pharmacologic effects of anxiolytic agents can be mapped as functional changes in the fear, stress and anxiety brain circuit. In this work we investigated the effects of a standard treatment, paroxetine (20mg/day), in subjects with Social Anxiety Disorder (SAD) versus placebo using different fMRI paradigms. The fMRI sessions, performed before and after the treatment, consisted of a public exposition of recorded performance task (PERPT), an emotional face processing task (EFPT) and a 6-min resting state followed by an off-scanner public speaking test. Paroxetine significantly improved the clinical conditions of SAD patients (n=17) vs. placebo (n=16) as measured with Clinical Global Inventory - Improvement (CGI-I) while no change was seen when using Liebowitz Social Anxiety Scale, as expected given the small size of the study population. Paroxetine reduced the activation of insula, thalamus and subgenual/anterior cingulate cortex (ACC) in PERPT. Resting-state fMRI assessment using Independent Component Analysis indicated that paroxetine reduced functional connectivity in insula, thalamus and ACC when compared with placebo. Both paradigms showed significant correlation with CGI-I in rostral prefrontal cortex. Conversely, paroxetine compared to placebo produced activation of right amygdala and bilateral insula and no effects in ACC when tested with EFPT. No treatment effects on distress scores were observed in the off-scanner Public Speaking Test. Overall this study supports the use of fMRI as sensitive approach to explore the neurobiological substrate of the effects of pharmacologic treatments and, in particular, of resting state fMRI given its simplicity and task independence.

3,4-methylenedioxymethamphetamine induces gene expression changes in rats related to serotonergic and dopaminergic systems, but not to neurotoxicity

3,4-Methylenedioxymethamphetamine (MDMA, ecstasy) is an amphetamine derivative widely abused by young adults. Although many studies have reported that relatively high doses of MDMA deplete serotonin (5-HT) content and decrease the availability of serotonin transporters (5-HTT), limited evidence is available as to the adaptive mechanisms taking place in gene expression levels in the brain following a dosing regimen of MDMA comparable to human consumption. In order to further clarify this issue, we used quantitative PCR to study the long-term changes induced by acute administration of MDMA (5 mg/kg × 3) in the expression of genes related to serotonergic and dopaminergic systems, as well as those related to cellular toxicity in the cortex, hippocampus, striatum, and brain stem of rats. Seven days after MDMA administration, we found a significantly lower expression of the 5-HTT (Slc6a4) and the vesicular monoamine transporter (Slc18a2) genes in the brain stem area. In the hippocampus, monoamine oxidase B (Maob) and tryptophan hydroxylase 2 (Tph2) gene expressions were increased. In the striatum, tyrosine hydroxylase (Th) expression was decreased, and a lower expression of α-synuclein (Snca) was observed in the cortex. In contrast, no significant changes were observed in the genes considered to be biomarkers of toxicity including the glial fibrillary acidic protein (Gfap) and the heat-shock 70 kD protein 1A (Hspa1a) in any of the structures assayed. These results suggest that MDMA promotes adaptive changes in genes related to serotonergic and dopaminergic functionality, but not in genes related to neurotoxicity.

COMT val158met and 5-HTTLPR genetic polymorphisms moderate executive control in cannabis users

The adverse effects of cannabis use on executive functions are still controversial, fostering the need for novel biomarkers able to unveil individual differences in the cognitive impact of cannabis consumption. Two common genetic polymorphisms have been linked to the neuroadaptive impact of Δ9-tetrahydrocannabinol (THC) exposure and to executive functions in animals: the catechol-O-methyltransferase (COMT) gene val158met polymorphism and the SLC6A4 gene 5-HTTLPR polymorphism. We aimed to test if these polymorphisms moderate the harmful effects of cannabis use on executive function in young cannabis users. We recruited 144 participants: 86 cannabis users and 58 non-drug user controls. Both groups were genotyped and matched for genetic makeup, sex, age, education, and IQ. We used a computerized neuropsychological battery to assess different aspects of executive functions: sustained attention (CANTAB Rapid Visual Information Processing Test, RVIP), working memory (N-back), monitoring/shifting (CANTAB ID/ED set shifting), planning (CANTAB Stockings of Cambridge, SOC), and decision-making (Iowa Gambling Task, IGT). We used general linear model-based analyses to test performance differences between cannabis users and controls as a function of genotypes. We found that: (i) daily cannabis use is not associated with executive function deficits; and (ii) COMT val158met and 5-HTTLPR polymorphisms moderate the link between cannabis use and executive performance. Cannabis users carrying the COMT val/val genotype exhibited lower accuracy of sustained attention, associated with a more strict response bias, than val/val non-users. Cannabis users carrying the COMT val allele also committed more monitoring/shifting errors than cannabis users carrying the met/met genotype. Finally, cannabis users carrying the 5-HTTLPR s/s genotype had worse IGT performance than s/s non-users. COMT and SLC6A4 genes moderate the impact of cannabis use on executive functions.

Optimization of [(11)C]raclopride positron emission tomographic rat studies: comparison of methods for image quantification

The goal of this study was to compare different quantification approaches and reconstruction methods to estimate the binding potential in [11C]raclopride studies in rats. The final aim was to determine if the results obtained with short-acquisition scanning were comparable to the results obtained with long-acquistion (conventional) scanning. We analyzed two rat data sets: a baseline versus a pretreatment study (with cold raclopride) and a young versus an old animal group comparison. The study results support the contention that optimization of [11C]raclopride positron emission tomographic studies in rats by shortening the acquisition time is feasible. In addition, filtered backprojection is recommended as a reconstruction algorithm, although iterative methods may be more sensitive to detect within-group differences.

Neural response to the observable self in social anxiety disorder

BACKGROUND

Distorted images of the observable self are considered crucial in the development and maintenance of social anxiety. We generated an experimental situation in which participants viewed themselves from an observer's perspective when exposed to scrutiny and evaluation by others. Method Twenty patients with social anxiety disorder (SAD) and 20 control subjects were assessed using functional magnetic resonance imaging (fMRI) during the public exposure of pre-recorded videos in which they were each shown performing a verbal task. The examiners acted as the audience in the experiment and rated performance. Whole-brain functional maps were computed using Statistical Parametric Mapping.

RESULTS

Robust activation was observed in regions related to self-face recognition, emotional response and general arousal in both study groups. Patients showed significantly greater activation only in the primary visual cortex. By contrast, they showed significant deactivation or smaller activation in dorsal frontoparietal and anterior cingulate cortices relevant to the cognitive control of negative emotion. Task-related anxiety ratings revealed a pattern of negative correlation with activation in this frontoparietal/cingulate network. Importantly, the relationship between social anxiety scores and neural response showed an inverted-U function with positive correlations in the lower score range and negative correlations in the higher range.

CONCLUSIONS

Our findings suggest that exposure to scrutiny and evaluation in SAD may be associated with changes in cortical systems mediating the cognitive components of anxiety. Disorder severity seems to be relevant in shaping the neural response pattern, which is distinctively characterized by a reduced cortical response in the most severe cases.

Acute effects of a single, oral dose of d9-tetrahydrocannabinol (THC) and cannabidiol (CBD) administration in healthy volunteers

RATIONALE

Animal and humans studies suggest that the two main constituents of cannabis sativa, delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) have quite different acute effects. However, to date the two compounds have largely been studied separately.

OBJECTIVE

To evaluate and compare the acute pharmacological effects of both THC and CBD in the same human volunteers.

METHODS

A randomised, double-blind, cross-over, placebo controlled trial was conducted in 16 healthy male subjects. Oral THC 10 mg or CBD 600 mg or placebo was administered in three consecutive sessions, at one-month interval. Physiological measures and symptom ratings were assessed before, and at 1, 2 and 3 hours post drug administration. The area under the curve (AUC) between baseline and 3 hours, and the maximum absolute change from baseline at 2 hours were analysed by one-way repeated measures analysis of variance, with drug condition (THC or CBD or placebo) as the factor.

RESULTS

Relative to both placebo and CBD, administration of THC was associated with anxiety, dysphoria, positive psychotic symptoms, physical and mental sedation, subjective intoxication (AUC and effect at 2 hours: p < 0.01), an increase in heart rate (p < 0.05). There were no differences between CBD and placebo on any symptomatic, physiological variable.

CONCLUSIONS

In healthy volunteers, THC has marked acute behavioural and physiological effects, whereas CBD has proven to be safe and well tolerated.

Putting Clinical Pharmacology in Context: The Use of Popular Movies

The usefulness of movies to illustrate the psychological and sociological conflicts of medical practice is widely recognized. However, the use of popular movies to teach less oriented medical sciences, such as pharmacology is not so common. In the present review, we report the use of three films (Awakenings, Lorenzo's Oil, and Miss Evers' Boys) as a teaching tool to allow students to better understand some conflicts which appear in the domain of clinical pharmacology. These movies may help to introduce some relevant topics such as the difficulties of planning and performing clinical research with new drugs, the need of considering bioethical principles when doing research with human beings, and the social and psychological aspects of drug therapy. The films may increase the motivation of students to understand clinical pharmacology principles and may become a driving force for an increased desire to learn.

Structural and functional imaging studies in chronic cannabis users: a systematic review of adolescent and adult findings

Background

The growing concern about cannabis use, the most commonly used illicit drug worldwide, has led to a significant increase in the number of human studies using neuroimaging techniques to determine the effect of cannabis on brain structure and function. We conducted a systematic review to assess the evidence of the impact of chronic cannabis use on brain structure and function in adults and adolescents.

Methods

Papers published until August 2012 were included from EMBASE, Medline, PubMed and LILACS databases following a comprehensive search strategy and pre-determined set of criteria for article selection. Only neuroimaging studies involving chronic cannabis users with a matched control group were considered.

Results

One hundred and forty-two studies were identified, of which 43 met the established criteria. Eight studies were in adolescent population. Neuroimaging studies provide evidence of morphological brain alterations in both population groups, particularly in the medial temporal and frontal cortices, as well as the cerebellum. These effects may be related to the amount of cannabis exposure. Functional neuroimaging studies suggest different patterns of resting global and brain activity during the performance of several cognitive tasks both in adolescents and adults, which may indicate compensatory effects in response to chronic cannabis exposure.

Limitations

However, the results pointed out methodological limitations of the work conducted to date and considerable heterogeneity in the findings.

Conclusion

Chronic cannabis use may alter brain structure and function in adult and adolescent population. Further studies should consider the use of convergent methodology, prospective large samples involving adolescent to adulthood subjects, and data-sharing initiatives.

Drought episode modulates the response of river biofilms to triclosan

The consequences of global change on rivers include altered flow regime, and entrance of compounds that may be toxic to biota. When water is scarce, a reduced dilution capacity may amplify the effects of chemical pollution. Therefore, studying the response of natural communities to compromised water flow and to toxicants is critical for assessing how global change may affect river ecosystems. This work aims to investigate how an episode of drought might influence the response of river biofilms to pulses of triclosan (TCS). The objectives were to assess the separate and combined effects of simulated drought (achieved through drastic flow alteration) and of TCS exposure on biofilms growing in artificial channels. Thus, three-week-old biofilms were studied under four conditions: Control (normal water flow); Simulated Drought (1 week reduced flow+2 days interrupted flow); TCS only (normal water flow plus a 48-h pulse of TCS); and Simulated Drought+TCS. All channels were then left for 2 weeks under steady flow conditions, and their responses and recovery were studied. Several descriptors of biofilms were analyzed before and after each step. Flow reduction and subsequent interruption were found to provoke an increase in extracellular phosphatase activity, bacterial mortality and green algae biomass. The TCS pulses severely affected biofilms: they drastically reduced photosynthetic efficiency, the viability of bacteria and diatoms, and phosphate uptake. Latent consequences evidenced significant combined effects caused by the two stressors. The biofilms exposed only to TCS recovered far better than those subjected to both altered flow and subsequent TCS exposure: the latter suffered more persistent consequences, indicating that simulated drought amplified the toxicity of this compound. This finding has implications for river ecosystems, as it suggests that the toxicity of pollutants to biofilms may be exacerbated following a drought.

Human pharmacology of 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) after repeated doses taken 2 h apart

BACKGROUND

3,4-methylenedioxymethamphetamine (MDMA, ecstasy) is one of the most abused recreational drugs. Its usual pattern of misuse includes repeated doses taken over a short time period that could influence MDMA pharmacology and toxicity.

OBJECTIVE

This study aims to evaluate the pharmacokinetics and pharmacologically induced effects of two MDMA consecutive doses separated by 2 h.

METHODS

A randomized, double-blind, crossover, and placebo-controlled trial included ten male volunteers participating in two experimental sessions. MDMA was administered as a single 100-mg dose or as a repeated dose (50 mg followed by 100 mg, administered at 2 h apart). Outcome variables included pharmacokinetics, physiological, subjective, and psychomotor effects.

RESULTS

Following the repeated doses, plasma concentrations of MDMA were higher than those expected by simple dose accumulation (+16.2 % AUC; +12.8 % C (max)), but those of HMMA and HMA were significantly lower (-29.8 % AUC; -38.2 % C (max)). After the second dose, physiological effects, psychomotor performance, and subjective effects were lower than expected especially for euphoria and stimulation. MDMA-induced increases in diastolic and systolic arterial pressure and body temperature were in the range of those expected following MDMA concentrations.

CONCLUSIONS

MDMA pharmacokinetics and metabolic disposition following two doses separated by 2 h show that the contribution of the first dose to the MDMA-induced mechanism-based metabolic inhibition was already apparent. The concentrations of MDMA after the second dose were slightly higher than expected. The effects on blood pressure and temperature after the second administration were slightly higher than those following the first, but for heart rate and subjective variables these were lower than expected considering the MDMA concentrations achieved, suggesting a possible tolerance phenomenon.

Prioritization of chemicals in the aquatic environment based on risk assessment: analytical, modeling and regulatory perspective

The extensive and intensive use of chemicals in our developed, highly technological society includes more than 100,000 chemical substances. Significant scientific evidence has lead to the recognition that their improper use and release may result in undesirable and harmful side-effects on both the human and ecosystem health. To cope with them, appropriate risk assessment processes and related prioritization schemes have been developed in order to provide the necessary scientific support for regulatory procedures. In the present paper, two of the elements that constitute the core of risk assessment, namely occurrence and hazard effects, have been discussed. Recent advances in analytical chemistry (sample pre-treatment and instrumental equipment, etc.) have allowed for more comprehensive monitoring of environmental pollution reaching limits of detection up to sub ng L(-1). Alternative to analytical measurements, occurrence models can provide risk managers with a very interesting approach for estimating environmental concentrations from real or hypothetical scenarios. The most representative prioritization schemes used for issuing lists of concerning chemicals have also been examined and put in the context of existing environmental policies for protection strategies and regulations. Finally, new challenges in the field of risk-assessment have been outlined, including those posed by new materials (i.e., nanomaterials), transformation products, multi-chemical exposure, or extension of the risk assessment process to the whole ecosystem.