I269S Mutation in horse liver alcohol dehydrogenase S isoenzyme and its reactivity for steroids and retinoids

Ile-269 in horse liver alcohol dehydrogenase isoenzyme S(HLADH-S) was mutated to serine by phosphorothioate-based site-directed mutagenesis in order to study the role of the residue in coenzyme binding. The specific activity of the mutant(I269S) enzyme to ethanol was increased 49-fold. All turnover numbers of I269S enzyme toward 9 primary alcohols were increased. The mutant enzyme showed 3.6, 4.6, 11.6-fold higher catalytic efficiency for 5β-androstane-3,17-dione, 5β-cholanic acid-3-one and retinal than wild-type, respectively. The reaction mechanism of I269S enzyme was ordered bi bi as wild-type's. These results indicate that the hydrophobic interaction of Ile-269 residue with coenzyme plays an important role in dissociation of coenzyme from enzyme-coenzyme complex, which has been known as the rate limiting step of ADH reaction.     

Flavonoids fromCirsium rhinoceros

Six flavonoids were isolated from the aerial parts ofCirsium rhinoceros. The flavonoids were identified as apigenin, luteolin, pectolinarigenin-7-O-β-D-glucopyranoside, linarin, pectolinarin and hispidulin-7-O-α-L-rhamnopyranosyl-(1→2)-β-D-glucopyranoside on the basis of chemical and spectral evidence.     

Hydrolysis kinetics of metampicillin by high performance liquid chromatography

The hydrolysis of metampicillin to ampicillin was investigated using high performance liquid chromatography. We developed the simultaneous determination of metampicillin and ampicillin using a Zorbax CN column and 5% acetonitrile and 8% methanol in 0.02 M phosphate buffer (pH 7.0) as mobile phase. Metampicillin was hydrolyzed to ampicillin with half life of 41.5 min at physiological pH and temperature. In acidic pH, metampicillin was rapidly hydrolyzed to ampicillin within a chromatographic separation.     

Epimerization and Hydrolysis of Dalvastatin,a New Hydroxymethylglutaryl Coenzyme A (HMG-CoA) Reductase Inhibitor

In aqueous solutions, dalvastatin (1) undergoes epimerization as well as hydrolysis. The transformation of the drug was studied as a function of pH at 25°C in aqueous solutions containing 20% acetonitrile. At all pH values, first-order plots for the conversion are biphasic, indicating rapid equilibration of 1 with its epimer (2) and slower hydrolysis of 1 to the corresponding -hydroxy acid (3). Apparent first-order rate constants for the biexponential equation are given as a function of pH. The alkyl–oxygen cleavage of the lactone ring results in the epimerization of 1 to 2, whereas the acyl–oxygen cleavage results in the hydrolysis of 1 to 3. The epimerization is an S_N1 reaction reaching an equilibrium of [l] _eq/[2] _eq = 1.27. The epimerization rate is increased with an increase in the water content of the solvent. The hydrolysis of 1 to 3 is acid and base catalyzed. The hydrolysis is reversible in acidic media and irreversible in neutral and basic media. At pH values greater than 9, the hydrolysis reaction proceeds more rapidly than the epimerization.     

SEARCH FOR HERPES SIMPLEX VIRUS TYPE2（HSV－2）AND HUMAN PAPILLOMAVIRUS（HPV）IN THE NORMAL AND ABNORMAL CERVICAL SAMPLES

ＳＥＡＲＣＨＦＯＲＨＥＲＰＥＳＳＩＭＰＬＥＸＶＩＲＵＳＴＹＰＥ２（ＨＳＶ－２）ＡＮＤＨＵＭＡＮＰＡＰＩＬＬＯＭＡＶＩＲＵＳ（ＨＰＶ）ＩＮＴＨＥＮＯＲＭＡＬＡＮＤＡＢＮＯＲＭＡＬＣＥＲＶＩＣＡＬＳＡＭＰＬＥＳＺｈａｎｇＷｅｉ;张伟;ＪｉｎＳｈｕｎｑｉａ...     

Multiple effects on drug-sensitivity, genome stability and malignant potential by combinations of h-ras, C-myc and mutant p53 gene overexpression

Activation of specific oncogenes and inactivation of tumor suppressor genes play major roles in mechanisms leading to neoplastic transformation. The potential involvement of these genes in determining genome stability is an important issue. To examine the relationships between altered oncogene expression and the effects on genome stability, we have investigated the drug sensitivity properties of mouse 10T1/2 fibroblasts transfected with combinations of H-ras, c-myc and the proline 193 mutant form of p53. The relative colony forming efficiencies of these cells were investigated in the absence or presence of various concentrations of the chemotherapeutic agents, methotrexate, N-(phosphonacetyl)-L-aspartate (PALA) or hydroxyurea. The effects of altered oncogene expression were found to be drug and locus specific, and to lead to increased drug resistance (e.g. H-ras transfectants were significantly resistant to methotrexate or PALA), decreased drug resistance (e.g. H-ras/-myc transfectants were significantly less resistant to PALA or hydroxyurea than H-ras transfected cells), or to no significant change in drug sensitivity (e.g. H-ras transfected cells were not significantly different in sensitivity to hydroxyurea than non-transfected cells). Gene amplification was an important but not the only mechanism for drug resistance. Cells that were transfected with p53 (H-ras/p53 or H-ras/c-myc/p53) exhibited the greatest drug resistance properties with all three chemotherapeutic agents, in keeping with the important role of p53 in DNA repair and DNA amplification mechanisms. Although both H-ras/p53 and H-ras/c-myc/p53 groups exhibited very similar genome stability characteristics as determined by drug sensitivity results, they were significantly different in their abilities to produce transformed foci in vitro and lung metastases in vivo. The H-ras/c-myc/p53 transfected cells formed significantly higher numbers of transformed foci and exhibited a greater malignant potential. These results are consistent with observations that H-ras expression directly correlates with malignant potential, and that H-ras/c-myc/p53 transfected cells have higher H-ras expression than H-ras/p53 transfected cells. Alterations in genomic integrity through changes in onocogene expression play important roles in mechanisms determining drug sensitivity; in addition to genome destabilization, other events are critically involved in regulating transformed and malignant characteristics.     

舌脉诊法考

舌脉诊法主要观察舌腹面血管系统的变化,为我国所特有。《内经》首载舌脉刺血治疟、狂、忧虑无言、心病等,以盛即粗张为施术指征。晋以后发展为诊法,葛洪用于虏黄,巢元方用于噤黄与五色黄病情深浅判断,《医门方》用于预测难产母子吉凶,陈自明编《产难生死诀》以广流传。本法继承了络脉诊法的理论,重视络脉形色观察,以盛与青黑为逆,从血瘀痰郁辨证。明清未见明显发展,但作为奇穴刺血治舌肿、喉闭、黄疸并未中断,周学海发挥刘守真“玄府论”,倡舌细络瘀血说,难能可贵的是与今微循环障碍理论符合。１９６４年张赞臣再倡,研究者日众,临床多而基础少,认为对瘀证及肿瘤、肝病、肺心病有较高诊断价值。     

二甲苯对不同年龄大鼠脑组织形态学及神经细胞凋亡的影响

目的　探讨年龄对二甲苯神经毒作用的影响。方法　采用 Ｈ Ｅ 染色法和 Ｔ Ｕ Ｎ Ｅ Ｌ 技术对不同月龄大鼠的脑组织病理形态学和神经细胞凋亡情况进行了研究。结果　二甲苯５００ ｍ ｇ／ｋｇ 染毒后,２ 月龄组较８ 月龄组大鼠脑组织形态学改变相对严重,２ 月龄组染毒大鼠神经细胞凋亡的发生率为（１ ．５３ ±１ ．０６） 个／ 视野,明显高于同龄对照组的（０ ．９３ ±０ ．７５） 个／ 视野, Ｆ＝ １２ ．６５９ ６ , Ｐ＜ ０ ．００１ ;８ 月龄组染毒大鼠的神经细胞凋亡率为（１ ．６５ ±１ ．１１） 个／ 视野,明显高于同龄对照组的（１ ．１５ ±１ ．０７） 个／ 视野, Ｆ＝ ６ ．２６３ ３ , Ｐ＜ ０ ．０５ 。结论　低龄大鼠对二甲苯的神经毒作用更为敏感     

工频电磁场对人体免疫功能的作用

目的　探讨工频电磁场对人体免疫功能的影响。方法　检测２５ 例长期工作在３ ×１０５ Ｖ超高压环境中的工作人员与５ 例正常对照者的外周血Ｔ 淋巴细胞分泌白细胞介素２（ＩＬ２） 活性,白细胞介素２ 受体（ＩＬ２Ｒ） 表达;单核／ 巨噬细胞抗体依赖的细胞介导的细胞毒（ＡＤＣＣ） 效应,白细胞介素１５（ＩＬ１５） 活性;血清中ＩｇＧ、ＩｇＡ、ＩｇＭ 的水平。结果　（１） 观察组ＩＬ２ 活性为（３６２ ±７８） Ｕ／ｍｌ,明显高于对照组［（２５４ ±６７）Ｕ／ｍｌ］ ,差异有显著性（ Ｐ ＜ ０ ．０５） 。（２） 观察组ＩＬ２Ｒ 表达比率为２８ ．４ ％ ±３ ．２ ％ ,对照组为２２ ．８ ％ ±１０ ．７ ％ ,差异无显著性（ Ｐ ＞ ０ ．０５） 。（３） 观察组单核／ 巨噬细胞ＡＤＣＣ 效应及ＩＬ１５ 分泌水平均有增强或增高的趋势,但差异无显著性（ Ｐ ＞ ０ ．０５） 。（４） 观察组血清中ＩｇＧ 水平为（１０ ．３７ ±１ ．２８）ｇ／Ｌ,明显高于对照组［（８ ．８９ ±１ ．８８）ｇ／Ｌ］ ,差异有显著性（ Ｐ ＜ ０ ．０５） ,而血清中ＩｇＡ、Ｉｇ Ｍ 水平与对照组比较,差异无显著性（ Ｐ ＞ ０ ．０５） 。结论　长期工作在工频电磁场环境中人员的Ｔ