Vitamin K epoxide reductase expression and prostate cancer risk

Purpose

Increasing evidence has demonstrated that men taking the anticoagulant warfarin have a lower risk of developing prostate cancer. This phenomenon is not observed in other cancers. We sought to determine if the target of warfarin, vitamin K epoxide reductase (VKOR), is expressed in benign and cancerous prostate tissues and if a functional single nucleotide polymorphism (SNP) in the VKOR gene is associated with prostate cancer risk.

5-Lipoxygenase and leukotriene A<Subscript>4</Subscript> hydrolase expression in primary nephrotic syndrome

Gene expression of 5-lipoxygenase (5-LO) and leukotriene A₄ (LTA₄) hydrolase was analyzed in the peripheral blood of 48 children with active primary nephrotic syndrome (PNS) (group I), 27 children with PNS in remission (group II), and 20 controls. Group I included 34 patients with steroid-sensitive PNS (SSNS) and 14 patients with steroid-resistant PNS (SRNS). Total RNA purified from peripheral blood mononuclear (PBMN) cells was reverse transcribed into cDNA and amplified with specific primers in the polymerase chain reaction. All group I patients and none of the controls expressed 5-LO and LTA₄ hydrolase. Of group II children, 22.2% expressed 5-LO, while 51.9% expressed LTA₄ hydrolase. Among group I patients there was a significant positive correlation between the degree of proteinuria and the expression of 5-LO (r=0.27, P=0.03) and LTA₄ hydrolase (r=0.44, P=0.001). There was no difference in the degree of expression of both enzymes between SSNS and SRNS patients. In conclusion, leukotrienes may play a role in the pathogenesis of PNS in children, but they do not participate in the response of these patients to steroids.     

Expression of aminopeptidase B in the developing and adult rat retina

Aminopeptidase B (Ap-B), a ubiquitous enzyme, catalyses the amino-terminal cleavage of basic residues of peptide or protein substrates, indicating a role in precursor processing. The physiological function of Ap-B still remains an open question, even though its activity suggests that it could be involved in inflammatory processes and proliferation of tumor cells. This study was conducted to determine the expression of Ap-B in the developing and adult retina as a path to envisage physiological roles of Ap-B. RT-PCR and in situ hybridization were used to detect expression of Ap-B mRNA and activity tests, Western blotting and immunofluorescence microscopy were performed to identify and localize the enzyme in the rat retina. These biochemical and morphological methods show that Ap-B is expressed in the retina from embryo to adult. Expression level is restricted to specific layers (pigmented epithelium, outer and inner plexiform layers and ganglion cell layer) and is developmentally regulated. Moreover, a preliminary analysis indicates that Ap-B, the glucose transporter GLUT3 and choline acetyltransferase (ChAT) share a similar expression pattern in retina. Altogether, Ap-B appears predominantly expressed in neuronal cells lying in retinal layers containing neuritic extensions and synaptic junctions. Such expression is up-regulated during ontogenesis allowing to hypothesized that Ap-B participates in processes accompanying retinal neuronal cell differentiation.     

Lysosomal abnormalities in degenerating neurons link neuronal compromise to senile plaque development in Alzheimer disease

Antibodies to the lysosomal hydrolases, cathepsins B and D and β-hexosaminidase A, revealed alterations of the endosomal-lysosomal system in neurons of the Alzheimer disease brain, which preceded evident degenerative changes and became marked as atrophy, neurofibrillary pathology, or chromatolysis developed. At the earliest stages of cell atrophy, hydrolase-positive lysosomas accumulated at the basal pole and then massively throughout the perikarya and proximal dendrites of affected pyramidal neurons in Alzheimer prefrontal cortex and hippocampus, far exceeding the changes of normal aging. Secondary lysosomes as well as tertiary residual bodies (lysosomes/lipofuscin) increased implying stimulated, autophagocytosis and lysosomal system activation. Less affected brain regions, such as the thalamus, displayed similar though less extensive alterations. Certain thalamic neurons exhibited a distinctive lysosome-related abnormality characterized by the presence of cell surface blebs of varying size and number filled with intense hydrolase immunoreactivity. At more advanced stages of degeneration in still intact neurons, hydrolase-positive lipofuscin, particularly in the form of abnormal large aggregates, nearly filled the cytoplasm. Similar lipofuscin aggregates were oberved in abundance in the extracellular space following cell lysis and were usually associated with deposits of the β-amyloid protein. Degenerating neurons and their processes were the major source of these aggregates within senile plaques which contained high concentrations of acid hydrolases. We have shown in previous studies that these lysosomal hydrolases in plaques are enzymatically-active. The persistence of lysosomal structures in the brain parenchyma after neurons hyve degenerated is a striking and potentially diagnostic feature of Alzheimer disease which has not been observed, to our knowledge, in other degenerative diseases. The lysosomal response in degerating Alzheimer neurons represents a probable link between an early activation of the lysosomal system in at-risk, normal-appearing neurons and the end-stage contribution of lysosomes to senile plaque formation of emphasizes a slowly progressive disturbance of the lysosomal system throughout the development of Alzheimer disease.     

植物中水解酶Ch分布及农药对其活力的影响

作者在1976年发现所有植物各部位中均含有可能是一种水解酶(暂定名为水解酶Ch),它能水解2,6-二氯乙酰靛酚,使水溶液由浅黄色变为深蓝色.酶活力能被有机磷农药抑制,但不能水解溴化乙酰胆硷.本文研究了水解酶Ch在植物各部位中的分布情况,发现酶活力大小顺序为;种子>茎>根;新根>旧根>败叶>叶,块根>通常根,即更多地存在于植物生命力旺盛的部位,它可能在植物生理学方面起重要作用.     

Detoxication Strategy of Epoxide Hydrolase��The Basis for a Novel Threshold for Definable Genotoxic Carcinogens

From our recent work on the three-dimensional structure of epoxide hydrolases we theoretically deduced the likelihood of a two-step catalytic mechanism that we and others have subsequently experimentally confirmed. Analysis of the rate of the two steps by us and by others show that the first step—responsible for removal of the reactive epoxide from the system—works extraordinarily fast (typically three orders of magnitude faster than the second step), sucking up the epoxide like a sponge. Regeneration of the free enzyme (the second step of the catalytic mechanism) is slow. This becomes a toxicological problem only at doses of the epoxide that titrate the enzyme out. Our genotoxicity work shows that indeed this generates a practical threshold below which no genotoxicity is observed. This shows that—contrary to old dogma—practical thresholds exist for definable genotoxic carcinogens.     

HIV蛋白酶抑制剂的关键中间体——手性氨基环氧烷合成研究进展

拟肽类HIV蛋白酶抑制剂是临床治疗艾滋病的主要药物,它们的共性结构片段——（2R, 3S）-3-氨基-4-苯基-2-丁醇从关键中间体手性氨基环氧烷得到,笔者对该中间体的合成研究进行归纳和总结。     

The relationship between DNA adduct formation by benzo[a]pyrene and expression of its activation enzyme cytochrome P450 1A1 in rat

Benzo[a]pyrene (BaP) is a human carcinogen requiring metabolic activation prior to reaction with DNA. Cytochrome P450 (CYP) 1A1 is the most important hepatic and intestinal enzyme in both BaP activation and detoxification. CYP1A2 is also capable of oxidizing BaP, but to a lesser extent. The induction of CYP1A1/2 by BaP and/or β-naphthoflavone in liver and small intestine of rats was investigated. Both BaP and β-naphthoflavone induced CYP1A expression and increased enzyme activities in both organs. Moreover, the induction of CYP1A enzyme activities resulted in an increase in formation of BaP–DNA adducts detected by ³²P-postlabeling in rat liver and in the distal part of small intestine in vivo. The increases in CYP1A enzyme activity were also associated with bioactivation of BaP and elevated BaP–DNA adduct levels in ex vivo incubations of microsomes of both organs with DNA and BaP. These findings indicate a stimulating effect of both compounds on BaP-induced carcinogenesis.     

Sodium 2-propenyl thiosulfate derived from garlic induces phase II detoxification enzymes in rat hepatoma H4IIE cells

There is evidence that onions and garlic protect against cancer in humans. It has been suggested that this effect is partly due to the organosulfur compounds in Allium vegetables and that these substances act through induction of phase II detoxification enzymes. Here, we hypothesized that alk(en)yl thiosulfates, sodium n-propyl thiosulfate (NPTS), and sodium 2-propenyl thiosulfate (2PTS), which were identified in onions and garlic, respectively, may induce phase II enzymes. Therefore, rat hepatoma cells (H4IIE) were cultured with 1 to 100 μmol/L of NPTS or 2PTS for 48 hours at 37°C; and the activities and messenger RNA (mRNA) expression levels of phase II enzymes in H4IIE cells were investigated. The effects of diallyl trisulfide and tert-butylhydroquinone, known as phase II inducers, were also examined as positive controls and compared with the responses of NPTS and 2PTS. Quinone reductase (QR) activity and mRNA expression levels of QR and epoxide hydrolase 1 were significantly increased by 2PTS (P < .05-.005). In particular, QR activity was increased at a relatively low concentration of 2PTS (10 μmol/L). However, glutathione S-transferase activity and mRNA expression levels of glutathione S-transferase A5 and uridine diphosphate glucuronosyl transferase 1A1 were not changed by 2PTS. In contrast, NPTS did not affect the activities and mRNA expression levels of these phase II enzymes. These results show that 2PTS can induce phase II enzymes, and its inductive effect is comparable or superior to that of diallyl trisulfide and tert-butylhydroquinone.