Optimal immobilization of penicillinase for lon-selective electrode

Penicillin sensor was prepared by immobilizing penicillinase (Pcase) on H⁺-selective carboxylated poly (vinyl chloride) (PVC-COOH) membrane or cellulose filter membrane. The immobilization techniques are as follows. Pcase was immobilized with GTH on H⁺-selective PVC-COOH membrane or some amount of BSA was dropped on that membrane. Another method to make immobilization is to mix type I Pcase with GTH and drop on a cellulose filter membrane. According to immobilization techniques, there were some differences in response properties of enzyme electrodes, however, all electrodes responded to Pcase-resistant penicillin derivatives. Pcase immobilized on cellulose filter membrane with H⁺-selective PVC membrane eletrode was more stable and more sensitive to penicillinase-resistant penicillin derivatives than any other immobilization techniques.     

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.     

Kinetics study of palm oil hydrolysis using immobilized lipase Candida rugosa in packed bed reactor

Continuous hydrolysis of palm oil triglyceride in organic solvent using immobilized Candida rugosa on the Amberlite MB-1 as a source of immobilized lipase was studied in packed bed reactor. The enzymatic kinetics of hydrolysis reaction was studied by changing the substrate concentration, reaction temperature and residence time(tau) in the reactor. At 55 degrees C, the optimum water concentration was found to be 15 % weight per volume of solution (%w/v). The Michaelis-Menten kinetic model was used to obtain the reaction parameters, Km(app) and V max(app). The activation energies were found to be quite low indicating that the lipase-catalyzed process is controlled by diffusion of substrates. The Michaelis-Menten kinetic model was found to be suitable at low water concentration 10-15 %w/v of solution. At higher water concentration, substrate inhibition model was used for data analysis. Reactor operation was found to play an important role in the palm oil hydrolysis kinetic.     

True histiocytic lymphoma of the esophagus in an HIV-positive patient: an ultrastructural study

A 56-year-old white woman, seropositive for human immunodeficiency virus for 18 months without signs of acquired immunodeficiency syndrome, presented with retrosternal pain and progressive dysphagia secondary to an exophytic esophageal mass. Biopsies of the tumor showed a malignant neoplasm composed of pleomorphic, noncohesive cells growing in a diffuse, sheet-like fashion. Immunohistochemically, tumor cells were nonreactive with epithelial, lymphoid, neural, and monocyte/macrophage markers. Despite the noncontributory immunohistochemical findings, ultrastructural study of the tumor cells revealed convincing histiocytic features. Individual cells possessed long, slender filopodial projections, prominent Golgi apparatus, residual bodies, rare lysosomes, and prelysosomes. Immunoglobulin heavy chain and T-cell receptor gamma gene rearrangement studies detected no evidence of a clonal gene rearrangement. The patient responded poorly to chemotherapy and died 5 months after her initial symptom of dysphagia.     

共培养在小鼠胚胎发育过程中的作用

目的 通过人子宫内膜上皮与小鼠胚胎共培养,了解其对胚胎发育的影响。方法 观察共培养２４、３６ｈ及６０ｈ后的小鼠胚胎,并分级,结果 １共培养组停留于２细胞胚胎数显著少于对照组;２共培育２４、３６ｈ后,鼠胚１￣３有胚胎比例较对照组增加,差异有显著性;６０ｈ后,１￣３级胚胎比较与对照组相比差异无显著性。结论 人子宫内膜上皮与小鼠胚胎短期共培养有利于改善胚胎质量。     

三种镍化合物诱发转化细胞恶性度的鉴别与分析

目的 :利用已建立的三种镍化合物体外转化细胞进行裸鼠体内成瘤实验研究 ,比较它们恶性度的差异。方法 :三种镍化合物转化细胞接种BALB/C裸鼠 ,进行肿瘤细胞和转化细胞的透射电镜及扫描电镜观察。结果 :硫化镍 ,氯化镍 ,硫酸镍分别诱发的转化细胞都能在BALB/C裸鼠皮下形成肿瘤 ,病理组织学检查确定为纤维肉瘤。经扫描电镜与透射电镜观察瘤细胞形态与转化细胞有一定差别。结论 :本文进一步说明了三种镍化合物所诱发的细胞转化为恶性转化 ,且都具有体内致瘤性。     

(-)-Epiafzelechin: cyclooxygenase-1 inhibitor and anti-inflammatory agent from aerial parts of Celastrus orbiculatus.

An inhibitor of cyclooxygenase (COX)-1 activity of prostaglandin H2 synthase was isolated from aerial parts of Celastrus orbiculatus Thunb. (Celastraceae), an oriental folk medicine for rheumatoid arthritis by activity-guided column chromatographic methods. The COX inhibitor was identified as (-)-epiafzelechin, a member of flavan-3-ols by the structural analysis with HR-EI-mass, 1H-NMR and 13C-NMR spectral data. The compound exhibited a dose-dependent inhibition on the COX activity with an IC50 value of 15 microM. (-)-Epiafzelechin exhibited about 3-fold weaker inhibitory potency on the enzyme activity than indomethacin as a positive control. (-)-Epiafzelechin exhibited significant anti-inflammatory activity on carrageenin-induced mouse paw edema when the compound (100 mg/kg) was orally administrated at 1 h before carrageenin treatment.     

A study on analysis of particle size distribution

Analysis of particle size distribution of a sample of fine aluminum hydroxide powder was carried out by four different methods,i. e., conductivity, air permeability, gas-adsorption and sedimentation. Each method was reproducible. The results obtained by Coulter counter and sedimentation balance were similar, and the data obtained by Lea and Nurse permeameter and Stroehlein areameter were also similar. But the results differ considerably between the former and the latter. The advantages and disavantages of each method were discussed briefly and a means of comparing the results with those obtained by surface area measurements was shown.     

中药黄藤中的季铵生物碱研究

本文从中药黄藤的根及根茎中分得三种季铵生物碱,化学及光谱数据证明,一为掌叶防己碱(巴马汀),二为药根碱,三系伪非洲防己胺碱。后者为国内首次得到的一种天然伪原小檗碱型生物碱。