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Liquid Chromatography tandem mass spectrometry (LC-MS/MS) is the gold-standard approach for androgen analysis in biological fluids, superseding immunoassays in selectivity, particularly at low concentrations. While LC-MS/MS is established for analysis of testosterone and androstenedione, 5α-dihydrotestosterone (DHT) presents greater analytical challenges. DHT circulates at low nanomolar concentrations in men and lower in women, ionizing inefficiently and suffering from isobaric interference from other androgens. Even using current LC-MS/MS technology, large plasma volumes (&gt;0.5 mL) are required for detection, undesirable clinically and unsuitable for animals. This study investigated derivatization approaches using hydrazine-based reagents to enhance ionization efficiency and sensitivity of analysis of DHT by LC-MS/MS. Derivatization of DHT using 2-hydrazino-1-methylpyridine (HMP) and 2-hydrazino-4-(trifluoromethyl)-pyrimidine (HTP) were compared. A method was validated using an UHPLC interfaced by electrospradologies.Recent years have seen the field of extracellular vesicle (EV) studies burgeoning. This is mainly because EV constituents including nucleic acid, proteins, lipids, and metabolites are promising sources towards disease biomarker discovery. However, EV study remains challenging due to the complexity of biofluids as well as technical limitations during sample preparation. [https://www.selleckchem.com/TGF-beta.html TGF-beta family] Here, we proposed a simple method combing ultrafiltration (UF) and phospholipid affinity to collect high purity EVs from 30 mL of urine sample for their metabolomic profiling. Ultracentrifugation (UC) for EV isolation was applied as a reference method. Western blot (WB) analysis, nanoparticles tracking analysis (NTA) and electron microscopy (EM) were used to assess EV protein markers and to characterize vesicle size and morphology. The results revealed that more than 1010 EV particles could be isolated from a 30 mL urine sample by the proposed method, and the resulting EVs carry specific protein markers and had a typical "cup shape" morphology. This suggests that our method is suitable for EV isolation and can provide sufficient EV quantity to ensure downstream analysis. Further untargeted metabolomic profiling of isolated EVs by UHPLC-QTOF-MS detected 433 metabolites by our methods and 432 metabolites by UC with a MS/MS similarity score greater than 0.7. We then applied the lipid metabolites-targeted method using UHPLC-QTrap-MS with the MRM mode, which successfully detected 467 compounds from urine EVs. This indicates that UF integrating phospholipid affinity is a reliable method for metabolic analysis of urinary EVs, which holds the potential for EV clinical application towards biomarker investigation from their metabolites.It has become clear that sleep after learning has beneficial effects on the later retrieval of newly acquired memories. The neural mechanisms underlying these effects are becoming increasingly clear as well, particularly those of non-REM sleep. However, much is still unknown about the sleep and memory relationship the sleep state or features of sleep physiology that associate with memory performance often vary by task or experimental design, and the nature of this variability is not entirely clear. This paper describes pertinent features of sleep physiology and provides a detailed review of the scientific literature indicating beneficial effects of post-learning sleep on memory retrieval. This paper additionally introduces a hypothesis which attributes these beneficial effects of post-learning sleep to separable processes of memory reinforcement and memory refinement whereby reinforcement supports one's ability to retrieve a given memory and refinement supports the precision of that memory retrieval in the context of competitive alternatives. It is observed that features of non-REM sleep are involved in a post-learning substantiation of memory representations that benefit memory performance; thus, memory reinforcement is primarily attributed to non-REM sleep. Memory refinement is primarily attributed to REM sleep given evidence of bidirectional synaptic plasticity in REM sleep and findings from studies of selective REM sleep deprivation.In a series of cognitive and neuroimaging studies we investigated the relationships between adolescent sleep quality, white matter (WM) microstructural integrity and psychological distress. Collectively these studies showed that during early adolescence (12-14 years of age), sleep quality and psychological distress are significantly related. Sleep quality and the microstructure of the posterior limb of the internal capsule (PLIC), a WM tract that provides important connectivity between the cortex, thalamus and brain stem, were also shown to be significantly correlated as too were social connectedness and psychological distress. Longitudinally the uncinate fasciculus (UF), a WM tract that provides bidirectional connectivity between the amygdala and executive control centers in the Prefrontal cortex (PFC), was observed to be undergoing continued development during this period and sleep quality was shown to impact this development. Sleep latency was also shown to be a significant predictor of worry endured by early adolescents during future stressful situations. The current review places these findings within the broader literature and proposes an empirically supported model based in a theoretical framework. This model focuses on how fronto-limbic top-down control (or lack thereof) explains how poor sleep quality during early adolescence plays a crucial role in the initial development of anxiety disorders, and possibly in the reduced ability of anxiety disorder sufferers to benefit from cognitive reappraisal based therapies. While the findings outlined in these studies highlight the importance of sleep quality for WM development and in mitigating psychological distress, further research is required to further explicate the associations proposed within the model to allow causal inferences to be made.<br /><br /> Despite the growing body of cross-sectional research linking sleep problems and school burnout, hardly any research has investigated the longitudinal relationship between these two constructs. The aim of this study was to examine the bidirectional association between sleep problems and school burnout in middle school students.<br /><br /> A prospective design was used incorporating four time points (approximately 6-month interval). The participants were 1226 (50.3% girls) middle school students from 4 public schools who were in 7th grade at baseline. On average, participants were approximately 12.5 years old at the beginning of the study (M<br /><br /> =12.73, SD=0.68). All participants completed self-report measures in classrooms during regular school hours. The data were analyzed using a cross-lagged structural equation model. We also examined the stability of sleep problems and school burnout in time, and investigated the moderating role of gender.<br /><br /> The results indicated there is a moderate stability for both sleep problems and school burnout, and those students with sleep problems were more likely to develop school burnout, and vice versa.