Fish growth rates and lake sulphate explain variation in mercury levels in ninespine stickleback (Pungitius pungitius) on the Arctic Coastal Plain of Alaska.

Mercury concentrations in freshwater food webs are governed by complex biogeochemical and ecological interactions that spatially vary and are often mediated by climate. The Arctic Coastal Plain of Alaska (ACP) is a heterogeneous, lake-rich landscape where variability in mercury accumulation is poorly understood. Earlier research indicated that the level of catchment influence on lakes varied spatially on the ACP, and affected mercury accumulation in lake sediments. This work sought to determine drivers of spatial variation in mercury accumulation in lake food webs on the ACP. Three lakes that were a priori identified as "high catchment influence" (Reindeer Camp region) and three lakes that were a priori identified as "low catchment influence" (Atqasuk region) were sampled, and variability in water chemistry, food web ecology, and mercury accumulation was investigated. Among-lake differences in ninespine stickleback (Pungitius pungitius) length-adjusted methylmercury concentrations were significantly explained by sulphate concentration in lake water, a tracer of catchment runoff input. This effect was mediated by fish growth, which had no pattern between regions. Together, lake water sulphate concentration and fish age-at-size (proxy for growth) accounted for nearly all of the among-lake variability in length-adjusted methylmercury concentrations in stickleback (R2adj = 0.94, p < 0.01). The percentage of total mercury as methylmercury (a proxy for net Hg methylation) was higher in sediments of more autochthonous, "low catchment influence" lakes (p < 0.05), and in the periphyton of more allochthonous, "high catchment influence" lakes (p < 0.05). The results indicate that dominant sources of primary production (littoral macrophyte/biofilm vs. pelagic phytoplankton) and food web structure (detrital vs. grazing) are regulated by catchment characteristics on the ACP, and that this ultimately influences the amount of methylmercury in the aquatic food web. These results have important implications for predicting future mercury concentrations in fish in lakes where fish growth rates and catchment inputs may change in response to a changing climate.

Testosterone effects on functional amygdala lateralization: A study in adolescent transgender boys and cisgender boys and girls.

The influence of testosterone on the development of human brain lateralization has been subject of debate for a long time, partly because studies investigating this are necessarily mostly correlational. In the present study we used a quasi-experimental approach by assessing functional brain lateralization in trans boys (female sex assigned at birth, diagnosed with Gender Dysphoria, n = 21) before and after testosterone treatment, and compared these results to the functional lateralization of age-matched control groups of cisgender boys (n = 20) and girls (n = 21) around 16 years of age. The lateralization index of the amygdala was determined with functional magnetic resonance imaging (fMRI) during an emotional face matching task with angry and fearful faces, as the literature indicates that boys show more activation in the right amygdala than girls during the perception of emotional faces. As expected, the lateralization index in trans boys shifted towards the right amygdala after testosterone treatment, and the cumulative dose of testosterone treatment correlated significantly with amygdala lateralization after treatment. However, we did not find any significant group differences in lateralization and endogenous testosterone concentrations predicted rightward amygdala lateralization only in the cis boys, but not in cis girls or trans boys. These inconsistencies may be due to sex differences in sensitivity to testosterone or its metabolites, which would be a worthwhile course for future studies.

The economic impact of workplace wellness programmes in Canada.

BACKGROUND: The economic benefits of workplace wellness programmes (WWPs) are commonly cited as a reason for employers to implement such programmes; however, there is limited evidence outside of the US context exploring their economic impact. US evidence is less relevant in countries such as Canada with universal publicly funded health systems because of the lower potential employer savings from WWPs. AIMS: To conduct a systematic review of the Canadian literature investigating the economic impact of WWPs from an employer perspective. The quality of that evidence was also assessed. METHODS: We reviewed literature which included analyses of four economic outcomes: return on investment calculations; cost-effectiveness or cost-benefit analyses; valuations of productivity, turnover, absenteeism and/or presenteeism costs; and valuations of health care utilization costs. We applied the British Medical Journal (BMJ) Economic Evaluation Working Party Checklist to evaluate the quality of this evidence. RESULTS: Eight studies met the inclusion criteria. Although the studies showed that WWPs generated economic benefits from an employer perspective (largely from productivity changes), none of the reviewed studies were in the high-quality category (i.e. fulfilled at least 75% of the checklist criteria) and most had severe methodological issues. CONCLUSIONS: Though the Canadian literature pertaining to the economic impact of WWPs spans over three decades, robust evidence on this topic remains sparse. Future research should include a comparable control group, a time horizon of over a year, both direct and indirect costs, and researchers should apply analytical techniques that account for potential selection bias.

Validation of high-performance liquid chromatography-tandem mass spectrometry assays quantifying omacetaxine mepesuccinate and its 4'­des-methyl and cephalotaxine metabolites in human plasma and urine.

Omacetaxine mepesuccinate (hereafter called omacetaxine) is a modified cephalotaxine and is registered (Synribo(®)) for the treatment of adult patients with chronic myeloid leukemia (CML) with resistance and/or intolerance to two or more tyrosine kinase inhibitors (TKIs). To evaluate the pharmacokinetics of omacetaxine, sensitive high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) assays for the quantification of omacetaxine and its inactive 4'-des-methyl (4'-DMHHT) and cephalotaxine metabolites in human plasma and urine were developed and validated. Since omacetaxine is mainly metabolised by esterases, the plasma samples were immediately stabilised after collection with an esterase inhibitor and stored at a nominal temperature of -80°C. Urine samples were stored at -80°C immediately after collection. Protein precipitation was applied as the sample pretreatment method for the plasma samples, and urine samples were processed using solid-phase extraction (SPE). For both assays, the dried and reconstituted extracts were injected on a XBridge BEH Phenyl column for analysis of all analytes. Gradient elution was applied with 0.1% formic acid in water and methanol as mobile phases. Analytes were ionised using a turbospray ionisation source in positive mode and detected with a triple quadrupole mass spectrometer. The validated plasma assay quantifies all analytes in the concentration range of 0.1-100ng/mL and the urine assay in the range of 0.1-50ng/mL. At all concentrations, the accuracies were within ±15% of the nominal concentrations and precisions were ≤15%. The developed methods have successfully been applied in a human mass balance study of omacetaxine.

Climbing towards recovery: investigating physically injured combat veterans' psychosocial response to scaling Mt. Kilimanjaro.

PURPOSE: To explore physically injured combat veterans' psychosocial response to scaling Mt. Kilimanjaro. METHOD: Participants (n = 4) were male and ranged in age from 22 to 44 years. They had all been wounded as a result of active duty in Afghanistan between 15 and 42 months (M = 27.25) before the study. Data were collected throughout a 9-day climb on Mt. Kilimanjaro using multiple sources of ethnographic data collection techniques including semi-structured interviews and detailed observations. Data were analyzed using cross case analysis. RESULTS: The findings are divided into themes that were drawn out of the data to illustrate the participants' psychosocial response to their experience of climbing on Mt. Kilimanjaro. Key themes of self-determination, active coping and social support were identified from the data. CONCLUSION: Support for those in recovery from trauma should foster psychosocial resources needed for healthy functioning. Future research should explore the role of meaningful and challenging activities as a way of improving the experience of recovery following serious injury.

Serotonin and dopamine transporters in relation to neuropsychological functioning, personality traits and mood in young adult healthy subjects.

BACKGROUND: Serotonin and dopamine neurotransmitter systems are implicated in the regulation of mood, cognition and personality traits and their dysfunction is thought to be implicated in diverse psychopathologies. However, in healthy subjects the relationship between the serotonin and dopamine systems and neuropsychological functioning and personality traits is not clearly established. In the present study we investigated whether neuropsychological functioning, personality traits and mood states of a group of healthy subjects are associated with in vivo measures of serotonin transporters (SERTs) and dopamine transporters (DATs). METHOD: A total of 188 young healthy subjects underwent neuropsychological and subjective measurements of memory function, depression and impulsivity. Participants' SERT and DAT availability in predefined regions of interest were assessed using single photon emission computed tomography (SPECT) with the radiotracer [123I]ß-CIT. Individual magnetic resonance imaging (MRI) scans served as anatomic reference. RESULTS: We did not find any significant association between SERT or DAT availability and neuropsychological test performance or self-reported impulsivity and mood. There were no significant sex differences in SERT or DAT availability, but men performed significantly better on some tests of visuospatial functioning than women. CONCLUSIONS: Robust negative findings for striatal DAT availability seriously question earlier findings of positive associations between DAT availability and cognitive functions in healthy subjects. Our results also suggest that subcortical SERT availability is not associated with the neuropsychological functions and personality traits assessed. In summary, the present study suggests that neuropsychological and personality measurements in young healthy people are not associated with subcortical SERT or striatal DAT availabilities in the brain.

DNA microarray analysis of functionally discrete human brain regions reveals divergent transcriptional profiles.

Transcriptional profiles within discrete human brain regions are likely to reflect structural and functional specialization. Using DNA microarray technology, this study investigates differences in transcriptional profiles of highly divergent brain regions (the cerebellar cortex and the cerebral cortex) as well as differences between two closely related brain structures (the anterior cingulate cortex and the dorsolateral prefrontal cortex). Replication of this study across three independent laboratories, to address false-positive and false-negative results using microarray technology, is also discussed. We find greater than a thousand transcripts to be differentially expressed between cerebellum and cerebral cortex and very few transcripts to be differentially expressed between the two neocortical regions. We further characterized transcripts that were found to be specifically expressed within brain regions being compared and found that ontological classes representing signal transduction machinery, neurogenesis, synaptic transmission, and transcription factors were most highly represented.

The clinical teacher. A critical link in competence development.

Regardless of market conditions, staff development personnel are responsible for helping to meet the organization's need for competent staff. Collaboration between the organization's education and clinical staff is essential to effect a successful transfer from having knowledge to performing effectively. One organization's response to the challenge of competence development, and how a successful transfer of learning can be achieved by collaboration between clinical educators and clinical staff is reported.