陈年六堡茶对高脂血症小鼠的调脂护肝作用研究

为了探讨陈年六堡茶的调脂保肝功效,比较分析了不同年代六堡茶的主要化学物质的差异,再以高脂高糖饮食建立高脂血症小鼠模型,并用选定的陈年六堡茶水提物灌胃小鼠,观察小鼠相关生理生化指标及组织形态的变化。结果表明,陈化15年茶样被选为陈年六堡茶的代表,用于后续试验。与模型组相比,陈年六堡茶尤其中高剂量条件下能有效减轻高脂血症小鼠体重、肝重和降低肝系数,显著提高高密度脂蛋白-胆固醇(HDL-C)含量,降低血清中总胆固醇(TC)、甘油三酯(TG)和低密度脂蛋白-胆固醇(LDL-C)含量,降低谷丙转氨酶(ALT)和谷草转氨酶(AST)活力,改善大鼠肝脏氧化应激状态,具有统计学意义(P0.05或P0.01)。肝脏和脂肪组织病理切片显示,陈年六堡茶能明显减少肝细胞中脂滴的形成和抑制脂肪细胞膨大,呈剂量依赖关系。综上表明,陈年六堡茶在正常剂量条件下能有效改善因高脂高糖饮食所致的小鼠脂质代谢紊乱和肝脏损伤。     

茶黄素类抗肿瘤作用研究进展

简述了茶黄素类(Theaflavins，TFs)的化学结构，并从抗肿瘤、抗炎、抗氧化、抗病毒和抗心血管疾病五个方面综述了茶黄素类的药理作用，其中从肿瘤的发生、发展两个阶段着重分析了茶黄素类的作用机理，最后提出了TFs作为药品开发所存在的问题。     

The detection of Mycobacterium paratuberculosis in bovine faeces by isolation and the comparison of isolation with the examination of stained smears by light microscopy

The detection of Mycobacterium paratuberculosis organisms in bovine faeces by isolation was compared with that by the microscopical examination of Ziehl-Neelsen stained faecal smears for the presence of clumps of acid-fast M. paratuberculosis organisms. Faeces were obtained from cattle naturally or experimentally infected with M. paratuberculosis as well as from uninfected cattle. Microscopical examination was an unreliable method for the detection of M. paratuberculosis organisms, since the organisms were only detected in 99 (=55.9%) of 177 culturally positive faecal samples. 1111 addition, clumps of acid-fast organisms indistinguishable from M. paratuberculosis were also observed iin three of 18 samples from cattle free from Johne's disease and in 18 of 37 culturally negative samples from paratuberculous cattle. When M. paratuberculosis organisms were added to faeces from an uninfected cow, results showed that isolation attempts should be positive when 15 or more M. paratuberculosis organisms per gram of faeces are present.     

Comparison of an enzyme-linked immunospecific assay (ELISA) with the cold complement fixation test for the serodiagnosis of Brucella ovis infection

An enzyme-linked immunospecific assay (ELISA) for the serodiagnosis of Brucella ovis infection in sheep is described and compared with the cold complement fixation (CF) test. ELISA was performed in microtiter plates, using horse-radish peroxidase conjugated to anti-normal sheep serum globulins, and hydrogen peroxide plus o-phenylenediamine as substrate. A heated, cell-free B. ovis extract was used as antigen in both tests. ELISA was easier to perform, distinguished better between positive and negative sera, and did not need heat-inactivated sera.     

Calving patterns in seasonal dairy herds

Two field studies examined the calving patterns of cows in seasonal dairy herds in the Waikato (Field Study 1) and South Taranaki regions (Field Study 2). The first study examined patterns for cows commencing their second or subsequent lactation in herds which had used an inseminating service during the previous season. The second study included first lactation heifers only in 15 herds where animals had been naturally mated, and in 15 herds in which they had been synchronised and then artificially inseminated at the synchronised oestrus. The parameters describing calving patterns were based on the date for each herd's planned start of calving (PSC), which was 282 days from the date on which breeding commenced in the preceding season. The average interval from PSC to mean calving date for the 35 herds in Field Study 1 was 22 days, with individual herds ranging from 15 to 30 days. In herds with heifers which had been naturally mated (Field Study 2), it was 17.6 days compared to 11.0 days for previously synchronised animals. Calculating the intervals from PSC to median calving date and separately for the last two quartiles more effectively described a herd's calving pattern. The duration for the last quartile of the calving pattern was influenced by the extent and timing of induced calving. In Field Study 1, 88.6% of the 35 herd owners induced premature parturition in at least one cow. In these herds, 11.3% of cows were treated and calved prematurely. Only 61.7% of heifers which had previously been naturally mated calved by 3 weeks after PSC. Their calving dates were not evenly distributed over this 3-week period, with 9.8% in the first week and 25.6% in the third week. The calving pattern for heifers which had been previously synchronised showed several distinct peaks. Calvings to the synchronised mating were completed 15 days after PSC, by which time 64.7% of animals had calved. By 3 weeks after PSC, 72.9% of these heifers had calved. The results showed that there was considerable variation in calving patterns in seasonal dairy herds. This variation would have been due to differences in conception pattern, and the way induced calving had been applied. The calving pattern in heifers which had been naturally mated was less concentrated than had been expected. Synchronisation can significantly concentrate the calving pattern of these first lactation animals. The parameters used to describe calving patterns may be less applicable in herds in which a high proportion of animals is induced to calve prematurely, or where a whole herd is synchronised. Nonetheless, they do serve as an illustrative example of the variation in calving patterns among herds.     

Condensation of nonequilibrium phases of refractory silicates from the vapor

Silicon monoxide solid was evaporated in a bell jar containing reducing, neutral, or oxidizing atmospheres at pressures of a few torr. The vapor invariably condensed as smoke-sized particles of silicon sesquioxide, Si(2)O(3). The condensation of a solid whose composition differs from that of the parent gas and is apparently the least stable of the three solid species illustrates the importance of specific nucleation effects in the condensation process. This result has significant implications for theories of formation of grains in space.     

大湘西地区绿茶风味轮及其滋味类型判别模型构建

以湖南大湘西地区39份绿茶样本为材料,进行感官审评,绘制风味轮,并以主要滋味成分含量为基础建立滋味类型贝叶斯(Bayes)判别模型,旨在了解大湘西地区绿茶品质情况,并为提升大湘西地区绿茶品质提供参考。结果表明:大湘西地区绿茶品质优良,汤色以浅绿色居多;香气类型包括嫩香、嫩栗香、栗香和清香;滋味特征类型有鲜、爽、厚;在此基础上,构建了大湘西地区鲜爽型、醇浓型和其它型绿茶的判别函数,具有较好的准确性,可用于对大湘西地区绿茶滋味类型的预测。     

Effect of maternal cells transferred with colostrum on cellular responses to pathogen antigens in neonatal calves

OBJECTIVE: To assess the effect of maternal cells or cellular components on neonatal immune responses to intracellular pathogens in calves. ANIMALS: 15 Holstein calves. PROCEDURES: Calves were fed whole colostrum, frozen colostrum, or cell-free colostrum within 4 hours after birth. Leukocytes were obtained from calves before feeding colostrum and 1, 2, 7, 14, 21, and 28 days after ingestion. Proliferative responses against bovine viral diarrhea virus (BVDV) and mycobacterial purified protein derivatives were evaluated. Dams received a vaccine containing inactivated BVDV, but were not vaccinated against mycobacterial antigens. RESULTS: All calves had essentially no IgG in circulation at birth, but comparable and substantial concentrations by day 1. Calves that received whole colostrum had enhanced responses to BVDV antigen 1 and 2 days after ingestion of colostrum. In contrast, calves that received frozen colostrum or cell-free colostrum did not respond to BVDV. No differences were identified among the 3 groups in response to mycobacterial antigens. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that transfer of live maternal cells from colostrum to neonatal calves enhanced responses to antigens against which the dams had previously responded (BVDV), but not to antigens to which the dams were na?ve (mycobacterial purified protein derivatives). Results suggested that cell-mediated immune transfer to neonates can be enhanced by maternal vaccination.