Lipophilicity of opioids determined by a novel micromethod

The lipophilicity of various [mu]-selective opioids was determined by measuring their distribution between n-octanol and Tris.HCl buffer, pH 7.4, by a procedure requiring submicromolar concentrations (submilligram amounts) of the compounds. After partitioning at 25[deg]C, the concentration of opioids in the aqueous phase was quantified by their displacement of bound [3H]Tyr-Ala-Gly-(Me)Phe-Gly-ol (DAMGO) from opioid receptor in brain membranes. The obtained distribution coefficients (log Papp) agreed well with respective values determined previously with other, less sensitive or more cumbersome, methods of quantitation. The procedure is precise and versatile, and offers the routine assessment of lipophilicity as part of the in vitro characterization of opioids frequently available in limited quantities. In principle, the method is applicable to any compound whose binding to its receptor is quantifiable.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30114/1/0000489.pd

Synthesis and characterization of 7-nitrobenzo-2-oxa-1,3-diazole (NBD)-labeled fluorescent opioids

Alkylation of sarcosine with 4-chloro-nitrobenzo-2-oxa-1,3-diazole (NBD-chloride) furnished a fluorescent tag that was coupled with a tetrahydrothebaine derivative and [beta]-naltrexamine, respectively, to yield the fluorescent opioids 7[alpha]-(1R)-1-hydroxy-1-methyl-3-(4-hydroxyphenyl)-propyl]-6,14-endoethenotetrahydrothebaine NBD-sarcosinate (ASM-5-10) and N-cyclopropylmethyl-3-hydroxy-14[beta]-hydroxy-6[beta]-(NBD sarcosinyl)-amino-epoxymorphinan (ASM-5-67). The fluorescence intensity of the novel opioids allowed their detection at subnanomolar concentrations, and was dependent on the polarity of the solvent. Maximum quantum yield was obtained in ethyl acetate and ethanol, and minimal fluorescence in heptane and water. Compounds ASM-5-10 and ASM-5-67 displaced the opioid receptor binding of [3H]Tyr--Ala-Gly-(Me)Phe-Gly-ol in monkey brain membranes with IC50 values of 8.4 and 1.5nM, respectively. Whereas ASM-5-67 bound to [mu], [delta], and [kappa] receptors with comparable affinities, ASM-5-10 was [mu]-selective, with selectivity indices (ratio of respective IC50 values) of 0.04 for both [mu]/[delta] and [mu]/[kappa]. The sodium response ratio in binding revealed a pronounced agonist property of ASM-5-10. Both opioids were lipophilic, with octanol-water partition coefficients (log Papp) of 2.8 (ASM-5-10) and 1.0 (ASM-5-67). ASM-5-10 exhibited particularly strong membrane retention that was not reversible by four washes. Their favorable characteristics in fluorescence, receptor binding, and membrane interaction make these newly developed ligands useful molecular probes to study opioid receptor mechanisms.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30242/1/0000637.pd

GDF15 and Growth Control

Growth/differentiation factor-15 (GDF-15) is a distant member of the transforming growth factor β (TGF-β) superfamily and is widely expressed in multiple mammalian tissues. Its expression is highly regulated and is often induced in response to conditions associated with cellular stress. GDF15 serum levels have a strong association with many diseases, including inflammation, cancer, cardiovascular diseases, and obesity, and potentially serve as reliable predictor of disease progression. A functional role for GDF15 has been suggested in cancer, cardiovascular disease, kidney disease and metabolic disease. However, the knowledge of its pathophysiological function at the molecular level is still limited and requires more investigation. Recent identification of the endogenous receptor for GDF15 may provide additional insight in to its’ molecular mechanisms and relationship to disease states

A systematic review of resilient performance in defence and security settings

A narrative systematic literature review was conducted to explore resilient performance in defence and security settings. A search strategy was employed across a total of five databases, searching published articles from 2001 onwards that assessed performance and optimal function in relation to resilience, in defence and security personnel. Following narrative synthesis, studies were assessed for quality. Thirty-two articles met inclusion criteria across a range of performance domains, including, but not limited to, course selection, marksmanship, land navigation, and simulated captivity. Some of the key findings included measures of mental toughness, confidence, and a stress-is-enhancing mindset being positively associated with performance outcomes. There was mixed evidence for the predictive value of biomarkers, although there was some support for cortisol, dehydroepiandrosterone sulfate (DHEA-S) and neuropeptide-y (NPY), and vagal reactivity. Interventions to improve resilient performance were focused on mindfulness or general psychological skills, with effects generally clearer on cognitive tasks rather than direct performance outcomes in the field. In sum, no single measure, nor intervention was consistently associated with performance over a range of domains. To inform future work, findings from the present review have been used to develop a framework of resilient performance, with the aim to promote theoretically informed work

Photoperiodic regulation of FGF21 production in the Siberian hamster

FGF21 is an endocrine member of the fibroblast growth factor superfamily that has been shown to play an important role in the physiological response to nutrient deprivation. Food restriction enhances hepatic FGF21 production, which serves to engage an integrated response to energy deficit. Specifically, elevated FGF21 levels lead to reduced gluconeogenesis and increased hepatic ketogenesis. However, circulating FGF21 concentrations also paradoxically rise in states of metabolic dysfunction such as obesity. Furthermore, multiple peripheral tissues also produce FGF21 in addition to the liver, raising questions as to its endocrine and paracrine roles in the control of energy metabolism. The objectives of this study were to measure plasma FGF21 concentrations in the Siberian hamster, a rodent which undergoes a seasonal cycle of fattening and body weight gain in the long days (LD) of summer, followed by reduction of appetite and fat catabolism in the short days (SD) of winter. Groups of adult male hamsters were raised in long days, and then exposed to SD for up to 12 weeks. Chronic exposure of LD animals to SD led to a significant increase in circulating FGF21 concentrations. This elevation of circulating FGF21 was preceded by an increase in liver FGF21 protein production evident as early as 4 weeks of exposure to SD. FGF21 protein abundance was also increased significantly in interscapular brown adipose tissue, with a positive correlation between plasma levels of FGF21 and BAT protein abundance throughout the experimental period. Epididymal white adipose tissue and skeletal muscle (gastrocnemius) also produced FGF21, but levels did not change in response to a change in photoperiod. In summary, a natural programmed state of fat catabolism was associated with increased FGF21 production in the liver and BAT, consistent with the view that FGF21 has a role in adapting hamsters to the hypophagic winter state

Predicting future stability of ecosystem functioning under climate change

To maintain food security under global change, we need to consider the stability of ecosystem functioning into the future, particularly in resource production landscapes such as agricultural pasture. With ongoing climate change, extreme climatic events are predicted to become more frequent and severe globally, impacting crop production. The whole process of farming will become more uncertain, from choice of crop and crop productivity to the timing of the windows of opportunity for management decisions. Future agricultural policies, therefore, should not only consider changes in grassland production, but also its future stability. We use a case study of agricultural pastures on the island of Ireland to project different components of ecosystem stability (resistance, recovery time and recovery rate) to 2050 and 2080 under different future climate scenarios: a peak and decline scenario; and a continued emissions scenario. We show that future climate change will have substantial effects on both the future resistance and the recovery of ecosystem functioning following environmental disturbances, but the spatial pattern of effect sizes is not the same for these two measures of stability. National level analyses and agricultural policies, therefore, are likely to ignore regional variation in future change. From this, we encourage the translation of stability-based constructs, as well as maximum yield considerations, into future agricultural policy at the regional level

Dual effects of fibroblast growth factor 21 on hepatic energy metabolism

The aim of this study was to investigate the mechanisms by which FGF21 affects hepatic integration of carbohydrate and fat metabolism in Siberian hamsters, a natural model of adiposity. Twelve aged matched adult male Siberian hamsters maintained in their long day fat state since birth were randomly assigned to one of two treatment groups and were continuously infused with either vehicle (saline; n=6) or recombinant human FGF21 protein (1 mg/kg/day; n=6) for 14 days. FGF21 administration caused a 40% suppression (P<0.05) of hepatic pyruvate dehydrogenase complex (PDC), the rate-limiting step in glucose oxidation, a 34% decrease (P<0.05) in hepatic acetylcarnitine accumulation, an index of reduced PDC flux, a 35% increase (P<0.05) in long-chain acylcarnitine content (an index of flux through β-oxidation) and a 47% reduction (P<0.05) in hepatic lipid content. These effects were underpinned by increased protein abundance of PD kinase-4 (a negative regulator of PDC), the phosphorylated (inhibited) form of acetyl-CoA carboxylase (ACC, a negative regulator of delivery of fatty acids into the mitochondria), and the transcriptional co-regulators of energy metabolism peroxisome proliferator activated receptor gamma co-activator alpha (PGC1 and sirtuin-1 (SIRT-1). These findings provide novel mechanistic basis to support the notion that FGF21 exerts profound metabolic benefits in the liver by modulating nutrient flux through both carbohydrate (mediated by a PDK4-mediated suppression of PDC activity) and fat (mediated by deactivation of ACC) metabolism, and therefore may be an attractive target for protection from increased hepatic lipid content and insulin resistance that frequently accompany obesity and diabetes

The metabolic enzyme AdhE controls the virulence of <i>Escherichia coli</i> O157:H7

Classical studies have focused on the role that individual regulators play in controlling virulence gene expression. An emerging theme, however, is that bacterial metabolism also plays a key role in this process. Our previous work identified a series of proteins that were implicated in the regulation of virulence. One of these proteins was AdhE, a bi-functional acetaldehyde-CoA dehydrogenase and alcohol dehydrogenase. Deletion of its gene (adhE) resulted in elevated levels of extracellular acetate and a stark pleiotropic phenotype: strong suppression of the Type Three Secretion System (T3SS) and overexpression of non-functional flagella. Correspondingly, the adhE mutant bound poorly to host cells and was unable to swim. Furthermore, the mutant was significantly less virulent than its parent when tested in vivo, which supports the hypothesis that attachment and motility are central to the colonization process. The molecular basis by which AdhE affects virulence gene regulation was found to be multifactorial, involving acetate-stimulated transcription of flagella expression and post-transcriptional regulation of the T3SS through Hfq. Our study reveals fascinating insights into the links between bacterial physiology, the expression of virulence genes, and the underlying molecular mechanism mechanisms by which these processes are regulated