乳酸杆菌小分子抗菌肽生物学性质的初步研究

目的：探讨从酸菜汁中筛选分离到的乳酸杆菌所产抑菌物质的生物学性质。方法：菌株HD1．7发酵液经提取、纯化获得具有抑菌活性的干粉，采用尿素-SDS-PAGE不连续凝胶电泳法确定该物质的分子量，并对其热敏感性、酶敏感性、抑菌活性的适宜PH值及部分抑菌谱进行测定。结果：该物质具有蛋白质性质，分子量为14000左右的小肽，热稳定性好，可被胰蛋白酶水解，PH2时抑菌效果最佳。结论：此小分子肽是一种具有研发价值的微生物天然防腐剂。     

Effects of milk salt supplementation on bone mineral gain in pubertal Chinese adolescents: A 2-year randomized,double-blind,controlled, dose–response trial

Background/objectiveAdequate calcium intakes may enhance bone mineral accumulation during childhood. Little is known about the optimal calcium intake in Chinese adolescents. We examined the effects of three levels of calcium intake on bone mineral accretion in adolescents.MethodsThis was a 2-year randomized, double-blind, controlled trial. The subjects were randomly assigned to receive 40 g of milk powder containing 300 mg of calcium and 200 IU of vitamin D (Low-Ca group), or same milk powder additionally fortified with 300 mg of calcium (Mid-Ca group) or 600 mg of calcium (High-Ca group) for 2 years. The subjects' bone mineral density (BMD) and bone mineral content (BMC) at the total body, lumbar spine and left hip were determined by dual-energy X-ray absorptiometry at baseline and after the second year of treatment. Of the 111 girls and 109 boys (aged 12–14 years) enrolled, 91 girls and 91 boys completed the trial.ResultsThe girls in the High-Ca group (1,110 mg/d) had 2.3%, 2.7% and 2.6% greater BMD accretion at the total hip, femoral neck and shaft (P < 0.05) but not at total body less head and spine than those in the Low-Ca group (655 mg/d). A significant effect of higher calcium intake was also observed for percentage change of size-adjusted BMC at femur neck (P = 0.047). Bonferroni tests indicated no significant differences in the percentage changes in BMD, BMC or size-adjusted BMC between the Mid- and Low-Ca groups and between the High- and Mid-Ca groups. Extra calcium had no observable additional effect in the boys (P > 0.05).ConclusionAn intake of 1000 mg/d or more might be helpful in maximizing bone mineral accretion in the hip for girls. But further large studies are required to identify its long-term effects and the optimal calcium intake for boys.     

Bisphenol A disrupts glucose transport and neurophysiological role of IR/IRS/AKT/GSK3β axis in the brain of male mice

Bisphenol A (BPA), one of the most prevalent chemicals for daily use, was recently reported to disturb the homeostasis of energy metabolism and insulin signaling pathways, which might contribute to the increasing prevalence rate of mild cognitive impairment (MCI). However, the underlying mechanisms are remained poorly understood. Here we studied the effects of low dose BPA on glucose transport and the IR/IRS/AKT/GSK3β axis in adult male mice to delineate the association between insulin signaling disruption and neurotoxicity mediated by BPA. Mice were treated with subcutaneous injection of 100 μg/kg/d BPA or vehicle for 30 days, then the insulin signaling and glucose transporters in the hippocampus and prefrontal cortex were detected by western blot. Our results showed that mice treated with BPA displayed significant decrease of insulin sensitivity, and in glucose transporter 1, 3 (GLUT1, 3) protein levels in mouse brain. Meanwhile, hyperactivation of IR/IRS/AKT/GSK3β axis was detected in the brain of BPA treated mice. Noteworthily, significant increases of phosphorylated tau and β-APP were observed in BPA treated mice. These results strongly suggest that BPA exposure significantly disrupts brain insulin signaling and might be considered as a potential risk factor for neurodegenerative diseases.     

猪回肠末端转基因大米和亲本大米主要营养素的消化率

目的 比较转双反义淀粉分支酶(SBE)基因大米和亲本大米主要营养素的消化率.方法 7只五指山小型去势公猪进行回肠造瘘手术,术后小型猪按随机数字表法随机分为两组,采用交叉法分别喂饲转基因大米饲料和亲本大米饲料,收集食糜后分析两种大米中主要营养素的消化率.结果 转基因大米和亲本大米蛋白质的表观消化率分别为69.50%±4.50%、69.61%±8.40%(t=0.01,P=0.994);真消化率分别为87.55%±4.95%、87.64%±9.40%(t=0.01,P=0.994);脂肪消化率分别为72.86%±0.34%、77.89%±13.09%(t=0.95,P=0.378),碳水化合物消化率分别为72.92%±7.43%、92.35%±5.88%(t=4.27,P=0.005);转基因大米中17种氨基酸的表观消化率和真消化率与亲本大米没有差别.结论 转基因大米中碳水化合物消化率低于亲本大米,其余主要营养素的消化率与亲本大米具有实质等同性.