Melanocortin-4 receptors expressed by cholinergic neurons regulate energy balance and glucose homeostasis

Melanocortin-4 receptor (MC4R) mutations cause dysregulation of energy balance and hyperinsulinemia. We have used mouse models to study the physiological roles of extrahypothalamic MC4Rs. Re-expression of MC4Rs in cholinergic neurons (ChAT-Cre, loxTB MC4R mice) modestly reduced body weight gain without altering food intake and was sufficient to normalize energy expenditure and attenuate hyperglycemia and hyperinsulinemia. In contrast, restoration of MC4R expression in brainstem neurons including those in the dorsal motor nucleus of the vagus (Phox2b-Cre, loxTB MC4R mice) was sufficient to attenuate hyperinsulinemia, while the hyperglycemia and energy balance were not normalized. Additionally, hepatic insulin action and insulin-mediated suppression of hepatic glucose production were improved in ChAT-Cre, loxTB MC4R mice. These findings suggest that MC4Rs expressed by cholinergic neurons regulate energy expenditure and hepatic glucose production. Our results also provide further evidence of the dissociation in pathways mediating the effects of melanocortins on energy balance and glucose homeostasis.     

Genetic architecture of knee radiographic joint space in healthy young adults

Evidence of a significant genetic component to the age-related degenerative joint disease osteoarthritis has been established, but the nature of genetic influences on normal joint morphology in healthy individuals remains unclear. Following up on our previous findings on the influence of body habitus on phenotypic variation in knee joint space [Duren et al., Human Biology 78:353-364 (2006)], the objective of the current study was to estimate the heritability of radiographic joint space in the knees of healthy young adults from a community-based sample of families. A sample of 253 subjects (mean age = 18.02 years) from 87 randomly ascertained nuclear and extended families was examined. Joint width (JW) and minimum joint space in the medial (MJS) and lateral (LJS) knee compartments were measured. A maximum-likelihood variance components method was used to estimate the heritability of MJS, LJS, and JW. Covariate effects of age, sex, age-by-sex interactions, stature, weight, and BMI were simultaneously estimated. Genetic correlation analyses were then conducted to examine relationships between trait pairs. MJS, LJS, and JW were each significantly heritable (p < 0.001), with heritabilities of 0.52, 0.53, and 0.63, respectively. The genetic correlation between MJS and LJS was not significantly different from 1. Genetic correlations between each joint space measure and JW were not significantly different from 0. This study demonstrates a significant genetic component to radiographic knee joint space during young adulthood in healthy subjects. This suggests that there are specific but as yet unidentified genes that influence the morphology of healthy articular cartilage, the target tissue of osteoarthritis. Genetic correlation analyses indicate complete pleiotropy between MJS and LJS but genetic independence of joint space and JW.     

Genetic variation in spontaneous ovulation rate and LH receptor induction in mice

Selection for litter size (Line S1) and for post-weaning body weight gain (Line G) increased spontaneous ovulation rate in mature females by 69 and 73%, respectively, over that of randomly bred control mice (Line C). Inbreeding from S1 mice with selection for litter size produced highly inbred lines with elevated ovulation rates. Inbreeding from Line C mice produced a 21% divergence among lines, but did not depress the mean ovulation rate. Crosses of these lines revealed little heterosis in ovulation rate. LH receptors were induced by treating females from 22 days of age with diethylstilboestrol for 4 days and FSH for 2 days. The in-vitro binding of 125I-labelled hCG per microgram DNA decreased 56% in response to selection for litter size and increased 57% in response to selection for body weight gain, indicating high susceptibility of this trait to genetic change. Inbreeding from Line C mice produced a 135% divergence amongst lines, but did not depress the mean LH receptor induction. Body weight had significant effects on ovulation rate and LH receptor induction. These results show that selection for litter size and for rapid post-weaning body weight gain increases ovulation rate, but we suggest that different mechanisms are involved in these responses.     

利用分子量阵列平台进行特定序列甲基化分析的方法探讨

目的：探讨利用分子量阵列平台进行特定序列甲基化分析的方法。方法：通过对不同扩增条件和扩增效率及不同条件处理的质谱分析比较了MassArray平台进行甲基化分析的特点。结果：本研究通过与重亚硫酸盐测序结果比较证实,MassArray分子量阵列技术平台能够反映甲基化修饰的真实水平;通过不同条件下PCR扩增效率与甲基化分析的结果,发现扩增效率是制约MassArray分子量阵列技术平台甲基化分析的关键因素,而产物的放置时间和不同的处理没有明显影响甲基化分析。结论：Mas-sArray甲基化分析平台是高效快速检测甲基化修饰的平台,在使用过程中应该根据实际的实验条件,进行合理的质控。     

Intestinal inflammation caused by magnesium deficiency alters basal and oxidative stress-induced intestinal function

The aim of this study was to determine the effect of magnesium deficiency on small intestinal morphology and function. Rats were assigned to 4 groups and placed on magnesium sufficient or deficient diet for 1 or 3 weeks. Infiltration of neutrophils and mucosal injury were assessed in stained sections of small intestine. Magnesium deficiency alone induced a significant increase in neutrophil infiltration and increased vascular ICAM-1 expression, in the absence of changes in mucosal injury or expression of proinflammatory mediators. Magnesium deficiency was associated with hyposecretory epithelial cell responses and vascular macromolecular leak in the small intestine and lung, which was attributed partly to reduced expression of NOS-3. To determine the effect of hypomagnesmia on the intestinal responses to a known oxidative stress, groups of rats were randomized to either sham operation or superior mesenteric artery occlusion for 10 (non-injurious) or 30 (injurious) minutes followed by a 1- or 4-hour reperfusion period. In response to mesenteric ischemia/reperfusion, deficient rats showed exaggerated PMN influx, but similar mucosal injury. Intestinal ischemia in sufficient animals induced vascular macromolecular leak in the small intestine and lung at 4 hours of reperfusion, with levels similar to those observed in untreated deficient rats. Acute magnesium repletion of deficient rats 24 h before surgery attenuated the exaggerated inflammation in deficient rats. These data show that magnesium deficiency induced a subclinical inflammation in the small intestine in the absence of mucosal injury, but with significant functional changes in local and remote organs and increased sensitivity to oxidative stress. The opinions contained herein are those of the authors and are not to be construed as official policy or reflecting the views of the Department of Defense     

红籽瓜数量性状分析软件的设计与实现

主要介绍了如何使用面向对象技术对红籽瓜数量性状分析软件的设计,阐述了软件的设计过程,代码的编写。实现了对红籽瓜数量性状的分析。     

Regulation of tryptase from human lung mast cells by heparin. Stabilization of the active tetramer

Tryptase was shown to be stabilized as an enzymatically active tetramer by association with heparin and dissociated to inactive monomers in the absence of heparin at 37 degrees C in physiologic buffer and in plasma. There was a 50% loss of tryptase activity at 37 degrees C by 6-8 min in both physiologic buffer and plasma. When heparin glycosaminoglycan was present, tryptase retained nearly full activity for 2 h in buffer and in plasma. Tryptase activity also decayed under standard assay conditions in the presence of synthetic ester and peptide substrates unless bound to heparin. That tryptase is bound to heparin at the pH and physiologic NaCl concentrations employed was shown by chromatography of tryptase on heparin-agarose, gel filtration, and velocity sedimentation. Elution of tryptase from heparin-agarose occurred at 0.8 M NaCl. Maximal stabilization of tryptase by heparin occurred at a weight ratio to tryptase that was equal to or greater than unity. Kcat/Km ratios for tryptase-heparin at 0.15 M NaCl and 37 degrees C were 0.9 X 10(6) s-1 M-1 for tosyl-L-Gly-Pro-Lys-p-nitroanilide and 1.7 X 10(6) s-1 M-1 for p-tosyl-L-arginine methyl ester and are among the highest reported for tryptic enzymes. The mechanism of heparin-dependent stabilization of tryptase was not due to indirect ion binding properties of heparin and was analyzed by Superose 12 high performance liquid chromatography. Active enzyme eluted with an apparent Mr of 132,000 +/- 10,000 (n = 3, +/- S.D.), whereas tryptase inactivated by incubation without heparin eluted with an apparent Mr of 34,000. The tetrameric structure of diisopropyl fluorophosphate-inhibited tryptase was also preserved after incubation with heparin at 37 degrees C but was reduced to monomeric subunits after incubation without heparin. That no appreciable degradation of tryptase occurs under conditions that cause dissociation of subunits was directly shown by electrophoresis in sodium dodecyl sulfate-polyacrylamide gels. Two different subunits of 34,000 and 33,000 Mr (after reduction) present in the intact enzyme (calculated to be 134,000 Mr) were also detected unchanged after inactivation of tryptase by dissociation of its subunits. Thus, the selective localization and association of heparin and tryptase in the human mast cell secretory granule most likely plays a major role in the regulation of tryptase after secretion.