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Biomedical subjects

M Murata

Publications and source records attributed to M Murata.

At least 55 records · Page 3Linked to original sources
PubMed2001

Impact of genetic polymorphisms of 17-hydroxylase cytochrome P-450 (CYP17) and steroid 5alpha-reductase type II (SRD5A2) genes on prostate-cancer risk among the Japanese population.

Steroid hormones, especially testosterone, play important roles in the carcinogenesis of prostate cancer, and several studies have reported changes in risk with polymorphisms of genes involved in steroid metabolism. One example is the CYP17 gene, which has a polymorphic T-to-C substitution in the 5'-untranslated region giving rise to A1 (T) and A2 (C) alleles. Steroid 5alpha-reductase type II (SRD5A2), which converts testosterone to the metabolically more active dihydrotestosterone, exhibits 2 polymorphisms: V89L, which substitutes leucine for valine at codon 89, and A49T, which substitutes threonine for alanine at codon 49. We therefore designed a case-control study of 105 prostate-cancer patients and 210 controls with benign prostatic hyperplasia for the purpose of investigating the association between prostate-cancer risk and polymorphisms in the SRD5A2 and CYP17 genes among the Japanese. The frequency of the CYP17 A2/A2 genotype in cases (18.8%) was higher than in controls (14.5%). Compared with the A1/A1 genotype, the odds ratio for the A2/A2 genotype was 2.39 (95% confidence interval 1.04-5.46, p = 0.04). The frequency of the SRD5A2 LL genotype in cases (29.3%) was also slightly higher than in controls (24.6%), but this was not significant. Regarding the A49T polymorphism of SRD5A2, we could not detect the T allele in any of the examined samples. These data suggest a significant association between the CYP17 polymorphism and prostate-cancer risk among the Japanese.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed2001

Nomifensine-induced c-fos mRNA expression in discrete brain areas of the developing rat.

In rats, the subcutaneous injection of a dopamine uptake inhibitor, nomifensine (40 mg/kg), induced a significant increase in the c-fos mRNA levels in the neocortex on postnatal days 23 and 49, in the striatum on days 8, 14, 23 and 49, and in the hippocampus on day 23, when compared with saline administration. The repeated injection with nomifensine (40 mg/kg once daily) from postnatal days 49 to 53 and from 23 to 27, but not from days 8 to 12 and 14 to 18, resulted in an enhanced stereotypy response elicited by a subsequent challenge of the drug (5 mg/kg) 21 days after the last injection (behavioral sensitization). The present results suggest that the neuronal circuits regulated by nomifensine might undergo regionally-different developmental changes, which could be implicated in the development of behavioral expressions including nomifensine-induced stereotypy sensitization.

Age Factors↗
PubMed2001

Redox-sensitive transactivation of epidermal growth factor receptor by tumor necrosis factor confers the NF-kappa B activation.

Cross-communication between different signaling systems allows the integration of the great diversity of stimuli that a cell receives under varying physiological situations. In this paper we have explored the possibility that tumor necrosis factor (TNF) receptor signal cross-talks with epidermal growth factor (EGF) receptor signal on the nuclear factor-kappa B (NF-kappa B) activation pathway. We have demonstrated that overexpression of the EGF receptor (EGFR) in NIH3T3 cells significantly enhances TNF-induced NF-kappa B-dependent luciferase activity even without EGF, that EGF treatment has a synergistic effect on the induction of the reporter activity, and that this enhancement is suppressed by AG1478, EGFR-specific tyrosine kinase inhibitor. We also have shown that TNF induces tyrosine phosphorylation and internalization of the overexpressed EGFR in NIH3T3 cells and the endogenously expressed EGFR in A431 cells and that the transactivation by TNF is suppressed by N-acetyl-l-cysteine or overexpression of an endogenous reducing molecule, thioredoxin, but not by phosphatidylinositol 3-kinase inhibitors and protein kinase C inhibitor. Taken together, this evidence strongly suggests that EGFR transactivation by TNF, which is regulated in a redox-dependent manner, is playing a pivotal role in TNF-induced NF-kappa B activation.

Animals↗
PubMed2001

Genetic polymorphisms in cytochrome P450 (CYP) 1A1, CYP1A2, CYP2E1, glutathione S-transferase (GST) M1 and GSTT1 and susceptibility to prostate cancer in the Japanese population.

Associations between genetic polymorphisms of CYP1A1, CYP1A2, CYP2E1, GSTM1 and GSTT1 and prostate cancer (PCa) were analyzed in a case-control study of 315 individuals. The frequency of valine (Val)/valine (Val) genotypes for CYP1A1 was 11.3% in cases compared with 5.5% in controls, this polymorphism thus being associated with a significantly increased risk of PCa (odds ratio=2.4, 95% confidence interval (CI)=1.01-5.57). No links were detected between PCa and polymorphisms in other enzymes. However, the combination of CYP1A1 (Ile/Val and/or Val/Val) polymorphisms with the GSTM1 null type resulted in an OR of 2.2 (CI=1.10-4.57, 1.12-4.20, respectively). This study suggests that the CYP1A1 polymorphism and its combination with GSTM1 may be associated with PCa susceptibility in the Japanese population.

Case-Control Studies↗
PubMed2001

Mechanism of oxidative DNA damage induced by carcinogenic 4-aminobiphenyl.

DNA adduct formation is thought to be a major cause of DNA damage by carcinogenic aromatic amines. We investigated the ability of an aromatic amine, 4-aminobiphenyl (4-ABP) and its N-hydroxy metabolite (4-ABP(NHOH)) to cause oxidative DNA damage, using (32)P-labeled human DNA fragments from the p53 tumor suppressor gene and the c-Ha-ras-1 protooncogene. 4-ABP(NHOH) was found to cause Cu(II)-mediated DNA damage, especially at thymine residues. Addition of the endogenous reductant NADH led to dramatic enhancement of this process. Catalase and bathocuproine, a Cu(I)-specific chelator, reduced the amount of DNA damage, suggesting the involvement of H(2)O(2) and Cu(I). 4-ABP(NHOH) dose-dependently induced 8-hydroxy-2'-deoxyguanosine (8-OHdG) formation in the presence of Cu(ll) and NADH. 4-ABP(NHOH) conversion to nitrosobiphenyl, as measured by UV-visible spectroscopy, occurred rapidly in the presence of Cu(II), suggesting Cu(II)-mediated autoxidation. Increased amounts of 8-OHdG were found in HL-60 cells compared to the H(2)O(2)-resistant clone HP100 following 4-ABP(NHOH) treatment, further supporting the involvement of H(2)O(2). The present study demonstrates that an N-hydroxy derivative of 4-ABP induces oxidative DNA damage through H(2)O(2) in both a cell-free system and in cultured human cells. We conclude that, in addition to DNA adduct formation, oxidative DNA damage may play an important role in the carcinogenic process of 4-ABP.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2001

An endogenous redox molecule, thioredoxin, regulates transactivation of epidermal growth factor receptor and activation of NF-kappaB by lysophosphatidic acid.

Lysophosphatidic acid (LPA) is the smallest and simplest of all the glycerophospholipids that activates a specific GTP-binding protein coupled receptor to evoke multiple cellular responses. In this paper, we have demonstrated that LPA stimulates nuclear factor (NF)-kappaB-dependent gene induction in a neuronal cell line, NG108-15 and that this is under redox regulation by an endogenous molecule, thioredoxin. We also have shown that redox-sensitive transactivation of epidermal growth factor receptor by LPA confers NF-kappaB activation and small GTPase proteins are involved in this pathway.

Animals↗
PubMed2001

The role of aldose reductase in sugar cataract formation: aldose reductase plays a key role in lens epithelial cell death (apoptosis).

Since aldose reductase is localized primarily in lens epithelial cells, osmotic insults induced by the accumulation of sugar alcohols occur first in these cells. To determine whether the accumulation of sugar alcohols can induce lens epithelial cell death, galactose-induced apoptosis has been investigated in dog lens epithelial cells. Dog lens epithelial cells were cultured in Dulbecco's modified Eagle's mimimum essential medium (DMEM) supplemented with 20% fetal calf serum (FCS). After reaching confluence at fifth passage, the medium was replaced with the same DMEM medium containing 50 mM D-galactose and the cells were cultured for an additional 2 weeks. Almost all of the cells cultured in galactose medium were stained positively for apoptosis with the terminal deoxynucleotidyl transferance-mediated biotin-dUTP nick end labeling (TUNEL) technique. Agarose gel electrophoresis of these cells displayed obvious DNA fragmentation, known as a ladder formation. All of these apoptotic changes were absent in similar cells cultured in galactose medium containing 1 microM of the aldose reductase inhibitor AL 1576. Addition of AL 1576 also reduced the cellular galactitol levels from 123+/-10 microgram/10(6) cells (n=5) to 3.9+/-1.9 microgram/10(6) cells (n=5). These observations confirm that galactose induced apoptosis occurs in dog lens epithelial cells. Furthermore, the prevention of apoptosis by an aldose reductase inhibitor suggests that this apoptosis is linked to the accumulation of sugar alcohols.

Aldehyde Reductase↗
PubMed2001

Oxidative DNA damage by a metabolite of carcinogenic 1-nitropyrene.

Nitropyrenes are carcinogenic pollutants. Adduct formation following nitro-reduction is considered to be a major cause of nitropyrene-mediated DNA damage. We investigated the role of 1-nitrosopyrene, a metabolite of 1-nitropyrene, in causing oxidative DNA damage, using 32P-5'-end-labeled DNA. 1-Nitrosopyrene was found to facilitate Cu(II)-mediated DNA damage in the presence of NADH. Catalase and a Cu(I)-specific chelator attenuated DNA damage, indicating the involvement of H2O2 and Cu(I). Typical *OH scavenger did not have a significant effect. These results suggest that the main reactive species is probably a DNA-copper-hydroperoxo complex. We also measured 8-oxo-7,8-dihydro-2'-deoxyguanosine formation by 1-nitrosopyrene in the presence of Cu(II) and NADH, using an electrochemical detector coupled to a high-pressure liquid chromatograph. We conclude that oxidative DNA damage, in addition to DNA adduct formation, may play an important role in the carcinogenesis of nitropyrenes.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2001

Regeneration and recovery of the hearing function of the central auditory pathway by transplants of embryonic brain tissue in adult rats.

The present study is the first report of successful regeneration and recovery of hearing function of the central auditory pathway after transection in the adult rat. The ventral cochlear tract in the brain stem to pons was transected on one side in adult rats. Tissue from embryos (E14 to E16) was used to cover the lesion site. In 30% of the rats examined, the axons regrew beyond the transected site and regenerated into the denervated side and terminated at the normal targets. The hearing function of rats was elucidated by recording the auditory brain stem response (ABR). Rats with successful regeneration showed nearly normal ABR. In rats receiving simple transection without covering embryonic tissue, there was no regeneration and hearing function did not recover. Thus, the present findings contradict the widely held view that the adult mammalian central auditory system cannot be restored following damage.

Animals↗
PubMed2001

Establishment and characterization of cell-free translation/glycosylation in insect cell (Spodoptera frugiperda 21) extract prepared with high pressure treatment.

A coupled cell-free translation/glycosylation system, prepared from Spodoptera frugiperda insect cells, was established and optimized for protein production and glycosylation efficiency. Both translation and glycosylation were stimulated by addition of Mg2+, K+, ATP, GTP, creatine kinase and creatine phosphate, suggesting that glycoprotein productivity is largely determined by translation efficiency. However, high concentrations of creatine phosphate significantly inhibited translation. Spermidine stimulated both translation and glycosylation, but glycosylation required higher concentrations of spermidine than translation. Furthermore, extracts prepared at a nitrogen pressure of 10 kg/cm2 with the Mini-Bomb cell disruption chamber had the highest glycoprotein productivity; and extracts prepared at the higher nitrogen pressure of 15 kg/cm2 retained glycosylation ability. While extracts prepared with the Potter-Elvehjem homogenizer could mediate translation, no glycosylation was achieved. This indicated that the posttranslational machinery might survive disruption by high pressure, but not by physical shearing force. This insect cell-free system was able to synthesize approximately 25 microg of glycosylated gp120/ml of reaction mixture.

Animals↗
PubMed2001

Immunohistochemical localization of amelogenin in human odontogenic tumors, using a polyclonal antibody against bovine amelogenin.

In the present study, we investigated the localization of amelogenin in odontogenic tumors, using an anti-amelogenin polyclonal antibody. In order to make the antibody, antisera against an amelogenin fraction obtained from the enamel matrix of unerupted bovine tooth was raised in rabbits. By Western blot analysis, a main band of 25 kDa and six minor bands (6.8, 12, 18, 20, 23, and 27 kDa) were detected under nonreducing conditions. Immunoreactivity for the amelogenin was observed in ameloblasts and in the immature enamel matrix of 4-day-old rats. In odontogenic tumors, positive reactions for amelogenin were localized in limited areas in adenomatoid odontogenic tumor, calcifying odontogenic cyst, primary intraosseous carcinoma and odontoma. The strongest immunoreactions were shown in enamel matrices in odontomas. Small mineralized foci in epithelial nests showed positive reactions, and a few reactions were observed in epithelium adjacent to the mineralized foci. In calcifying odontogenic cysts, some ghost cells in the lining epithelium were strongly stained. The results indicate that the present antibody for amelogenin is useful for the determination of odontogenic tumors, especially in those in which small mineralized foci are present in the epithelial nests.

Amelogenin↗
PubMed2001

Cholesteryl ester transfer protein polymorphism associated with macroangiopathy in Japanese patients with type 2 diabetes.

A polymorphism in the gene for cholesteryl ester transfer protein (CETP) has been reported to be associated with serum cholesterol levels and risk for atherosclerotic vascular diseases, and to clarify the relationship between the gene polymorphism for CETP and macroangiopathy in diabetes mellitus, a cross-sectional study was performed. The subjects of the study were182 Japanese (age: 59.6+/-8.6 years) with type 2 diabetes and no signs of renal dysfunction, 24 of whom had macroangiopathy, and 158 of whom did not. The genotype of the subjects for the TaqIB polymorphism of CETP in intron one was analyzed by using polymerase chain reaction - restriction fragment length polymorphism. Serum CETP levels were significantly higher in the B1/B1 genotype than in the other genotypes (P<0.05). The serum CETP levels were correlated with the serum LDL cholesterol levels (P<0.01), but not with the HDL cholesterol levels. Macroangiopathy was more frequently observed in subjects with the B1/B1 genotype than in the other genotypes (odds ratio=2.953, 95% confidence interval=1.250-6.977, P=0.0136). Logistic regression analysis revealed that the CETP genotype was independently associated with macroangiopathy. The exact mechanism underlying the association remains unknown, but differences in serum CETP levels may be involved.

Aged↗
PubMed2001

Zonisamide has beneficial effects on Parkinson's disease patients.

Zonisamide (ZNS) is a generally well tolerated anticonvulsant that has beneficial effects on Parkinson's disease (PD). ZNS (300 mg/day) given to a patient with PD who incidentally had convulsive attacks, ameliorated the attacks and, surprisingly, his parkinsonian symptoms. We, therefore, carried out an open trial of ZNS on nine patients with PD. Patients were given 50-200 mg/day ZNS in addition to their anti-PD drugs. Seven clearly showed lessening of symptoms, especially wearing-off. We speculate that long lasting activation of dopamine synthesis by ZNS ameliorates parkinsonian symptoms, in particular wearing-off.

Aged↗
PubMed2001

Accumulation of beta-catenin in the cytoplasm and the nuclei during the early hepatic tumorigenesis.

Hepatocellular carcinomas (HCCs) are thought to develop as well-differentiated tumors and progress to less-differentiated tumors. However, the genetic changes underlying the development and progression of HCCs are not well understood. Recent studies have shown frequent beta-catenin gene activation in HCCs by somatic alterations involving exon 3, resulting in the activation of the Wnt/Wingless signal transduction pathway. However, the exact process in which activation of Wnt/Wingless signal transduction pathway occurs during hepatic tumorigenesis remains to be elucidated. The aim of the present study was to investigate at what stage of hepatocellular tumorigenesis this pathway was activated. Altered expression of beta-catenin was investigated immunohistochemically with special reference to the grade of histological differentiation in 41 HCCs and eight dysplastic nodules. Mutational analysis of the beta-catenin gene with single-strand conformation polymorphism method and polymerase chain reaction amplification was related with the expression of this protein. beta-Catenin was expressed in the cytoplasm and the nuclei in three cases among eight dysplastic nodules, in four cases among 20 well differentiated HCCs, in five cases among 15 moderately differentiated HCCs, and one case among six poorly differentiated HCCs, respectively. Expression of beta-catenin in the cytoplasm and the nuclei was associated in one case with mutation and two cases without mutation for beta-catenin gene among 11 screened HCCs. It was concluded that beta-catenin was accumulated in the cytoplasm and the nuclei in pre-cancerous lesions of the liver and might contribute, at least in part, to hepatic tumorigenesis.

Journal Article↗
PubMed2001

Requirement of glutathione and cysteine in guanine-specific oxidation of DNA by carcinogenic potassium bromate.

Potassium bromate (KBrO3), a food additive, induces renal-cell tumors in rats. KBrO3 induced 8-oxo-7, 8-dihydro-2'-deoxyguanosine (8-oxodG) formation in human leukemia cell line HL-60 as well as in its H2O2-resistant clone, HP100, suggesting no involvement of H2O2. Depletion of GSH by buthionine sulfoximine (BSO) had a little inhibitory effect on KBrO3-induced 8-oxodG formation. However, the amount of 8-oxodG was still significantly higher than that in control, suggesting that intracellular Cys can affect KBrO3 to oxidize DNA, when GSH decreased. KBrO3 caused 8-oxodG in isolated DNA in the presence of GSH (tripeptide; gamma-GluCysGly), gamma-GluCys, CysGly, or Cys. Methional completely inhibited 8-oxodG formation induced by KBrO3 plus GSH, but typical hydroxyl radical scavengers, SOD and catalase, had little or no inhibitory effects. When bromine solution (BrO(-)) was used instead of BrO3(-), similar scavenger effects were observed. Experiments with 32P-labeled DNA fragments obtained from the human p53 tumor suppressor gene and the c-Ha-ras-1 protooncogene suggested that KBrO3 induced 8-oxodG formation at 5'-site guanine of GG and GGG sequences of double-stranded DNA in the presence of GSH and that treatment of formamidopyrimidine-DNA glycosylase led to chain cleavages at the guanine residues. ESR spin-trapping studies showed that 1:2:2:1 quartet DMPO (5,5-dimethyl-1-pyrroline N-oxide) spectrum similar to DMPO/hydroxy radical (*OH) adduct, but the signals were not inhibited by ethanol. Therefore, the signal seemed not to be due to *OH but byproduct due to oxidation of DMPO by the reactive species. The signals were suppressed by the addition of dGMP, but not by other mononucleotides, suggesting the specific reactivity with guanine. On the basis of our results and previous literature, it is speculated that reduction of KBrO3 by SH compounds in renal proximal tubular cells yields bromine oxides and bromine radicals, which are the reactive species that cause guanine oxidation, leading to renal carcinogenesis of KBrO3.

Animals↗
PubMed2001

Acrylonitrile enhances H2O2-mediated DNA damage via nitrogen-centered radical formation.

Acrylonitrile (ACN) is widely used as a monomer in the polymer industry. Studies on carcinogenicity in rats exposed to ACN showed increased incidences of tumors including glial cell tumors of central nervous system and increased production of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG) in glial cells. Using a high performance liquid chromatograph equipped with an electrochemical detector, we revealed that ACN enhanced the formation of 8-oxo-dG induced by H2O2 and Cu(II) whereas ACN itself did not cause DNA damage. The enhancing effect of ACN was much more efficient in the double-stranded DNA than that in the single-stranded DNA. Experiments with 32P-labeled DNA revealed that addition of ACN enhanced the site-specific DNA damage at guanines, particularly at 5'-site of the GG and GGG sequences while H2O2/Cu(II) induced piperidine-labile sites at thymine, cytosine, and guanine residues. An electron spin resonance spectroscopy using alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone showed that a nitrogen-centered radical was generated from ACN in the presence of H2O2 and Cu(II). It is considered that ACN enhances H2O2-mediated DNA damage via nitrogen-centered radical formation. We will discuss the mechanism of the enhancing effect on oxidative DNA damage in relation to expression of ACN carcinogenicity.

Acrylonitrile↗