Characterization and modulation by drugs of sheep liver microsomal flavin monooxygenase activity

The flavin monooxygenases (FMO) catalyse the NADPH and oxygen-dependent oxidation of a wide range of nucleophilic nitrogen-, sulfur-, phosphorus-, and selenium heteroatom-containing chemicals, drugs, and agricultural agents. In the present study, sheep liver microsomal FMO activity was determined by measuring the S-oxidation rate of methimazole and the average specific activity obtained from different microsomal preparations was found to be 3.8 +/- 1.5 nmol methimazole oxidized min(-1) mg(-1) microsomal protein (mean +/- SE, n = 7). The presence of 0.1% Triton X-100 in the reaction mixture caused an increase of specific sheep liver microsomal FMO activity towards methimazole to 6.1 +/- 1.4 nmol methimazole oxidized min(-1) mg(-1) microsomal protein (mean +/- SE, n = 6). Metabolism of imipramine and chlorpromazine was measured by following the oxidation of cofactor NADPH spectrophotometrically at 340 nm. Sheep liver microsomal FMO activity towards imipramine and chlorpromazine was found to be 10.7 and 12.3 nmol NADPH oxidized min(-1) mg(-1) microsomal protein, respectively. Characterization of sheep liver enzyme was carried out using methimazole as substrate and the maximum FMO enzyme activity was detected at 37 degrees C and at pH 8.0. The apparent K(m) value of sheep liver microsomal FMO for methimazole was 0.118 mM. Effects of the detergents Triton X-100, Cholate, and Emulgen 913, on FMO activity were determined and FMO activity was found to increase with the addition of detergents to the reaction medium. Sheep liver microsomal FMO-catalysed methimazole oxidation was inhibited by imipramine and chlorpromazine when these drugs were used at high concentrations. Western blot-immunochemical analysis revealed the presence of FMO3 in sheep liver microsomes.     

Effects of simvastatin treatment on oxidant/antioxidant state and ultrastructure of streptozotocin-diabetic rat lung

In the present study, we investigated the effects of simvastatin, a 3-hydroxy-3-methyl-glutaryl coenzyme A reductase inhibitor, on lipid metabolism, lipid peroxidation, antioxidant enzyme activities and ultrastructure of diabetic rat lung. Diabetes was induced by a single injection of streptozotocin (45 mg kg(-1), i.p.). After 8 weeks induction of diabetes, some control and diabetic rats were treated with simvastatin (10 mg kg(-1) rat day(-1); orally) for 4 weeks. Diabetes resulted in significantly high levels of blood glucose and plasma lipids. Malondialdehyde levels were unchanged after 12-week-old diabetic rats, whereas catalase activity significantly decreased in the lung. Glutathione peroxidase activity and nitric oxide level were significantly elevated in the diabetic lung. Histological analysis of the diabetic lung revealed some deterioration in the structure. Simvastatin treatment reduced plasma lipid levels and partially decreased the severity of hyperglycaemia. Catalase, glutathione peroxidase activities and nitric oxide levels were partially restored and accompanied by improved structure in diabetic lung by the simvastatin treatment. These results suggest that structural disturbances and alteration of antioxidative enzyme activities occurred in diabetic lung. Simvastatin treatment may provide some benefits in the maintenance of antioxidant status and structural organization of diabetes-induced injury of lung.     

Role of K-ras and Pten in the development of mouse models of endometriosis and endometrioid ovarian cancer

Epithelial ovarian tumors present a complex clinical, diagnostic and therapeutic challenge because of the difficulty of early detection, lack of known precursor lesions and high mortality rates. Endometrioid ovarian carcinomas are frequently associated with endometriosis, but the mechanism for this association remains unknown. Here we present the first genetic models of peritoneal endometriosis and endometrioid ovarian adenocarcinoma in mice, both based on the activation of an oncogenic K-ras allele. In addition, we find that expression of oncogenic K-ras or conditional Pten deletion within the ovarian surface epithelium gives rise to preneoplastic ovarian lesions with an endometrioid glandular morphology. Furthermore, the combination of the two mutations in the ovary leads to the induction of invasive and widely metastatic endometrioid ovarian adenocarcinomas with complete penetrance and a disease latency of only 7 weeks. The ovarian cancer model described in this study recapitulates the specific tumor histomorphology and metastatic potential of the human disease.     

Recent advances in gene expression data clustering: a case study with comparative results

Several advanced techniques have been proposed for data clustering and many of them have been applied to gene expression data, with partial success. The high dimensionality and the multitude of admissible perspectives for data analysis of gene expression require additional computational resources, such as hierarchical structures and dynamic allocation of resources. We present an immune-inspired hierarchical clustering device, called hierarchical artificial immune network (HaiNet), especially devoted to the analysis of gene expression data. This technique was applied to a newly generated data set, involving maize plants exposed to different aluminum concentrations. The performance of the algorithm was compared with that of a self-organizing map, which is commonly adopted to deal with gene expression data sets. More consistent and informative results were obtained with HaiNet.     

菜心中SDS-PAGE向负极泳动的富含苯丙氨酸的蛋白的发现

在提取乙醇酸氧化酶同工酶的过程中, 发现了一种在SDS变性下向负极泳动的富含苯丙氨酸的碱性蛋白.在3次重复实验中, 均可以从SDS-PAGE后的负极缓冲液中获得这种蛋白, 其碱性与酸性氨基酸残基的比例分别高达1.46、1.28和0.89,而苯丙氨酸含量分别高达为60.00%、65.62%和62.30%.其余氨基酸残基的含量则和普通蛋白的相近似.由于该富含苯丙氨酸的碱性蛋白是水溶性的, 碱性氨基酸残基应主要分布在蛋白的表面,而苯丙氨酸则组成一个强疏水内核.     

Alpha Lipoic Acid Alleviates Oxidative Stress and Preserves Blood Brain Permeability in Rats with Subarachnoid Hemorrhage

The neuroprotective effect of alpha lipoic acid (ALA; 100 mg/kg, po), a dithiol antioxidant, on experimentally induced subarachnoid hemorrhage (SAH) was assessed in Wistar albino rats. Neurological examination scores recorded at the 48th h of SAH induction were increased in SAH groups, which were accompanied with significant increases in the formation of reactive oxygen species, DNA fragmentation ratios, malondialdehyde levels and myeloperoxidase activity, while significant decreases in the brain glutathione content and Na⁺, K⁺-ATPase activity were observed. On the other hand, ALA treatment reversed all these biochemical indices as well as SAH-induced histopathological alterations. Increased brain edema, impaired blood-brain-barrier permeability and neurological scores were also improved by ALA treatment. The results demonstrate that ALA exerts neuroprotective effects via the enhancement of endogenous antioxidant enzyme activity, the inhibition of neutrophil accumulation and free radical generation, suggesting a therapeutic potential in reducing secondary injury after SAH in patients.     

The effect of receptor protein tyrosine phosphatase kappa on the change of cell adhesion and proliferation induced by N‐acetylglucosaminyltransferase V

N‐acetylglucosaminyltransferase V (GnT‐V) has been reported to be positively associated with tumor progression, but its mechanism still remains unknown. In the present study, we found that GnT‐V overexpression not only changed the glycosylation of receptor protein tyrosine phosphatase kappa (RPTPκ) but also decreased its protein level. Moreover, GnT‐V overexpression decreased cell calcium‐independent adhesion and increased the tyrosine phosphorylation level of β‐catenin, in which RPTPκ played an important role. Since RPTPκ has an RXKR motif, which is a favored cleavage site for furin, we used furin inhibitor to further explore the effect of RPTPκ on the change of cell adhesion and β‐catenin signaling induced by GnT‐V. Our results showed that preventing RPTPκ cleavage rescued the above effects of GnT‐V, suggesting that furin cleavage could be one of the factors for RPTPκ to regulate cell adhesion and β‐catenin signaling in GnT‐V overexpression cell lines. In addition, the increased tyrosine phosphorylation level of β‐catenin was associated with the increased nuclear level of β‐catenin and downstream signaling molecules such as c‐myc and cyclin D1 that were associated with cell proliferation. Our results suggest that GnT‐V could decrease human hepatoma SMMC‐7721 cell adhesion and promote cell proliferation partially through RPTPκ. J. Cell. Biochem. 109: 113–123, 2010. © 2009 Wiley‐Liss, Inc.