Hypocholesterolaemic mechanism of bitter melon aqueous extracts via inhibition of pancreatic cholesterol esterase and reduction of cholesterol micellar solubility

This study investigated the hypocholesterolaemic effects of bitter melon aqueous extracts (BMAE) in vitro, the inhibitory effects of BMAE on pancreatic cholesterol esterase (CEase) and incorporation of cholesterol into micelles were investigated. BMAE decreased the in vitro micellar solubility of cholesterol in a dose-dependent manner. The conformation of CEase was investigated by means of circular dichroism (CD) and fluorescence. The result revealed the decrease of α-helix contents, increase of β-sheet and exposure of aromatic amino acid residuals. The incorporation of cholesterol into micelles was inhibited by BMAE. A complex was observed by transmission electron microscopy (TEM), which indicated interaction between cholesterol and BMAE. The result revealed that BMAE can play a role in decreased intestinal cholesterol absorption via inhibition of CEase, and of micelle formation.     

The use of experimental studies to reveal suspected neurotoxic chemicals as occupational hazards: acute and chronic exposures to organic solvents.

The nervous system differs from many other body organs by its central control of vital functions and its low regeneration capacity. Organic solvents have, as a group, been suspected to have neurotoxic effects. Because of their similar physical properties and the fact that in industrial uses, they are often present in various mixtures, organic solvents have also been regarded, unfortunately, to induce common neurotoxic effects. However, it is evident from experimental studies using specified exposure conditions that different organic solvents have very diverse neurotoxic effects and also that the toxic mechanism may differ between acute and chronic exposure. No specific method used to describe a neurotoxic effect or single toxic response can be used for the overall occupational risk assessment of all organic solvents. Each solvent has to be considered as having its own unique toxic effects.     

Prognostic significance of cytochemical analysis of leukemic M2 blasts

Cytochemical analysis of leukemic blasts from 46 patients with acute myeloblastic M2 leukemia (according to the FAB classification) was performed before and after cytostatic therapy, and compared with findings obtained in 20 age- and sex-matched control subjects. Cytochemical findings for myeloperoxidase (MPO), Sudan black B, acid phosphatase and alpha-naphthyl-acetate esterase (ANAE) were related to the achievement of the first complete remission (CR),i.e. data were compared after the patients had been divided into CR and non-CR groups. The analysis clearly showed that a high proportion of myeloperoxidase- and, to a lesser extent, Sudan black B-positive blasts before treatment may have constituted a significantly unfavourable prognostic factor.     

致倦库蚊有机磷抗性相关扩增酯酶B基因的多样性

本实验从佛山和成都两地的致倦库蚊群体中筛选出３个酯酶类型不同的有机磷（ＯＰ）抗性品系，ＦＳ－１、ＦＳ－２和ＣＤ－１品系。各品系的酯酶基因Ｂ扩增水平、酯酶活性和ＯＰ抗性水平三者一致。各品系酯酶Ｂ基因限制性酶切片段比较分析表明，我国的ＯＰ抗生库蚊群体中不仅有世界性分布的酯酶Ｂ１和Ｂ２，而且在佛山和成都地区各有一个新的独立扩增的酯酶Ｂ，分别命名为Ｂ６和Ｂ７。     

Inhibition of HLA B8-restricted recognition by unrelated peptides: evidence for allosteric inhibition

A panel of synthetic peptides representing human lymphocyte antigen (HLA) B8, other class I and class II restricted T cell epitopes and two B cell epitopes, were all able to compete with recognition of a HLA B8 restricted epitope by a cytotoxic T cell clone. Competition was obtained when the competitor peptides were added either before or after the target epitope. The target epitope also had a slow off rate, implicating allosteric inhibition. The presence of non-specific, allosteric binding sites may interfere with experiments attempting to define immunologically relevant MHC binding specificities.     

N-(Acyloxyalkoxycarbonyl) derivatives as potential prodrugs of amines. II. esterase-catalysed release of parent amines from model prodrugs

N-(Acetoxyethoxycarbonyl) derivatives of primary amines released a major fraction of the parent amine in the desired free form in plasma but a significant fraction of the undesired N-acetylated parent amine was also produced. The fraction of the parent amines released from the carbamate derivatives of the primary amines was greater in human plasma than in pH 7.4 buffer. In human plasma, the N-(acetoxyethoxycarbonyl) derivative of a secondary amine released the parent amine in a quantitative manner at a rate higher than that observed in pH 7.4 buffer. Experimental results suggested that the observed catalysis of the release of the parent amines from N-(acetoxyethoxycarbonyl) derivatives of primary and secondary amines was due to participation by plasma esterases. The data suggested that N-(acetoxyethoxycarbonyl) derivatives are well suited for use as prodrugs of secondary amines. Their utility as prodrugs of primary amines is more problematic and cannot be predicted prior to in-vivo studies for the individual compound.     

5种拟钉螺酯酶同工酶酶谱的比较研究

采用聚丙烯酰胺凝胶垂直平板电泳技术，对湖北和四川两省５种拟钉螺的酯酶同工酶酶谱进行比较研究，并以湖北钉螺作对照，５种拟钉螺酯酶同工酶共分离出８条酶带，酶谱可分成３区，即ＥＳＴ－１、ＥＳＴ－２、ＥＳＴ－３，其基本特征与钉螺显著不同，很容易通过酶谱将拟钉螺与钉螺区分开，同时，５种拟钉螺的酯酶同工酶酶谱之间均存在一定的差异，说明拟钉螺种间酯酶同工酶存在多态，而种间差异程度似与地域隔离的远近有关。结果提示拟钉螺酯酶同工酶的酶谱特征既有助于拟钉螺属的鉴定，又有助于拟钉螺近缘种的区分，从而对拟钉螺的分类有较大的参考价值。     

不同时程给予抗精神病药物对大鼠脑内AchE活性的影响

目的 探索常敏和超敏状态时乙酰胆碱酯酶活性的变化及该变化与锥体外系症状（ＥＰＳ）的可能关系。方法 应用分光光度法测定大鼠脑皮层、海马和纹状体ＡｃｈＥ催化碘化乙酰硫代胆碱水解的速率而确定酶的活性。结果 急性给予利血平、氯氮平、氟哌啶醇对大鼠纹状体、海马和皮层的ＡｃｈＥ活性无显著影响；以相同剂得的利血平、氯氮平和氟哌啶醇连续给药７ｄ和２１ｄ，利血平和氟哌啶醇显著降低纹状体和海马ＡｃｈＥ活性，氯氮平仅在     

假单胞菌胆固醇酯酶的生产Ⅰ.菌种筛选和发酵条件的研究

通过平板初筛和摇瓶复筛,从371株菌中筛得一株有工业生产价值的胆固醇酯酶产生菌,并对它进行了发酵条件的研究。用所获得的胆固醇酯酶配制的三酶试剂具有良好的稳定性,适用于临床检测。     

脾LAK细胞培养上清中BLT酯酶活性的动态观察

脾ＬＡＫ细胞培养上清有前后两个杀伤活性高峰，以第１１ｄ为界，第一个活性高峰与上清中ＢＬＴ酯酶活性呈正相关。含血清和无血清的培养体系产生ＢＬＴ酯酶的机理可能不同。在有高活性ｒＩＬ－２时，ＢＬＴ酯酶的分泌与无血清培养液中有无２－ＭＥ相关。