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Biomedical subjects

N Kato

Publications and source records attributed to N Kato.

At least 433 records · Page 24Linked to original sources
PubMed1996

Potent and long-lasting anticonvulsant effects of 1-naphthylacetyl spermine, an analogue of Joro spider toxin, against amygdaloid kindled seizures in rats.

The anticonvulsant effect of 1-naphthylacetyl spermine (1-NA-Spm), an analogue of Joro spider toxin, against amygdaloid kindled seizures was studied in rats. 1-NA-Spm (10, 20 and 40 micrograms/rat) dose-dependently improved kindled seizures and shortened the afterdischarge duration 30 min after the administration. The anticonvulsant effect was observed even one day after the drug, and then gradually disappeared within 4 days. The present findings demonstrate that 1-NA-Spm acts as a potent and long-acting anticonvulsant against amygdaloid kindled seizures, and also suggest, together with the previous findings, that the calcium-permeable AMPA receptors, which are selectively antagonized by 1-NA-Spm, play a critical role in the seizure generation mechanism of amygdaloid kindling.

Amygdala↗
PubMed1996

Gene therapy for alpha-fetoprotein-producing human hepatoma cells by adenovirus-mediated transfer of the herpes simplex virus thymidine kinase gene.

We have developed a recombinant replication-defective adenovirus containing human alpha-fetoprotein (AFP) promoter/enhancer to direct cell type-specific expression of the herpes simplex virus thymidine kinase (HSVtk) gene to AFP-producing hepatocellular carcinoma (HCC) cells. After an in vitro infection by a recombinant adenovirus carrying the lacZ gene under the control of human AFP promoter/enhancer (AdAFPlacZ), an expression of the lacZ gene was demonstrated efficiently in AFP-producing HuH-7 and HepG2 cell lines, but not in AFP-nonproducing HLE and HLF cell lines, although lacZ gene expression was demonstrated in all these cell lines when infected with adenovirus vector carrying lacZ gene driven by the beta-actin-based promoter. Expression of the HSVtk gene by adenovirus, from AFP promoter/enhancer (AdAFPtk) induced the cells sensitive to ganciclovir (GCV) in the AFP-producing cell line efficiently, but not in AFP-nonproducing HLF hepatoma cells. An in vitro bystander effect was observed when only 10% of the cells were infected with AdAFPtk. These findings suggest that the AFP promoter/enhancer sequence can provide the tumor-specific activity for the therapeutic gene expression, and that the AdAFPtk vector induces the selective growth inhibition by GCV in the adenovirus-infected human hepatoma cells in vitro. Recombinant adenovirus transfer of the HSVtk gene under the control of tumor-specific promoter followed by GCV may have promise as a targeted in situ treatment for solid neoplasms.

Adenoviridae↗
PubMed1996

cDNA cloning and gene expression of ascorbate oxidase in tobacco.

A cDNA clone for ascorbate oxidase (AAO) has been isolated from a cDNA library of tobacco (Nicotiana tabacum) cells. The identity of the amino acid sequence deduced from tobacco AAO cDNA to that from pumpkin AAO cDNA was 68%, which was much lower than the identity (80%) between pumpkin and cucumber AAO. AAO activity in tobacco cells was much lower than that in pumpkin cells, whereas the immunoreactive protein in tobacco cells was more abundant than that in pumpkin cells. We suppose that AAO protein in tobacco cells may be less active than that in pumpkin cells. Genomic Southern blotting suggested that AAO in tobacco was encoded by a single-copy gene. Nothern blotting revealed that mRNA of AAO was highly expressed in young and growing tissues of tobacco plant.

Amino Acid Sequence↗
PubMed1996

Types of methicillin-resistant Staphylococcus aureus associated with high mortality in patients with bacteremia.

Forty-seven strains of methicillin-resistant Staphylococcus aureus (MRSA) isolated from 47 patients with bacteremia were analyzed by chromosomal DNA digestion pattern using pulsed-field gel electrophoresis and evaluated for serological coagulase type, enterotoxin type, and toxic shock syndrome toxin-1 production. The mortality rate was significantly higher in the older patients (> or = 51 years of age) than in the younger patients (< or = 50 years of age) (50% vs. 4%, p = 0.0007). Methicillin-resistant Staphylococcus aureus strains of serological coagulase type II were more likely to be associated with mortality in older patients than were strains of the other types (p = 0.037).

Adolescent↗
PubMed1996

Relapses or reinfections: analysis of a case of Clostridium difficile-associated colitis by two typing systems.

Immunoblotting and pulsed-field gel electrophoresis of Clostridium difficile isolates were employed to differentiate reinfection by a newly acquired strain from relapse by an original strain in a 10-year-old patient with four episodes of C. difficile-associated colitis. Immunoblot typing demonstrated subserogroup K-1 of serogroup K for the first and second organisms, subserogroup A-1 of serogroup A for the third organism, and subserogroup G-4 of serogroup G for the fourth organism. PFGE analysis revealed consistent results with immunoblot analysis except that the strains from the fourth episode, whose DNA constantly degraded, were nontypable by this method. Five separate isolates of C. difficile from a specimen of each episode showed identical PFGE patterns, indicating that infections of multiple strains probably did not occur in this patient. These typing results suggested that the second episode after a 17-day course of vancomycin therapy represented a relapse by the strain causing the first episode, and that the third and fourth episodes after tapering vancomycin therapy were reinfections by other strains. Both immunoblot and PFGE typing systems are promising tools for analyzing recurrence of C. difficile infection.

Anti-Bacterial Agents↗
PubMed1996

The role of vasopressin, somatostatin and GABA in febrile convulsion in rat pups.

In order to further elucidate a possible role of neuropeptides and GABA in the pathogenesis of febrile convulsions, we studied changes of immunoreactive-arginine vasopressin (IR-AVP), IR-somatostatin (IR-SRIF) and gamma-aminobutyric acid (GABA) in the rat brain after febrile convulsions induced by ultra-red light (UR). Male Wistar rats at 16 days of age irradiated with UR developed generalized convulsions after 4.9 +/- 0.5 min irradiation. Six rats were killed by microwave irradiation 3 min after UR irradiation prior to convulsion development, and 29 rats were killed either 0 min, 2 h, 6 h, 24 h or 48 h after febrile convulsions. Non-irradiated rats served as controls. The rat brain was dissected into 4 regions; amygdala, hypothalamus, cortex and hippocampus, and subjected to radioimmunoassays. IR-AVP levels in hypothalamus were increased 3 min after UR and decreased at 2 h and 6 h after the convulsions. IR-SRIF levels were increased in cortex and hippocampus at 3 min after UR and 0 min after the convulsions. The GABA content increased in all regions tested at 2 h and 6 h after the convulsions. These results suggest that AVP, SRIF and GABA may be involved in the pathogenesis of febrile convulsions in different ways.

Animals↗
PubMed1996

Expression of c-fos mRNA after audiogenic seizure in adult rats with neonatal hypothyroidism.

In situ hybridization histochemistry was used to evaluate the expression of the immediate-early gene c-fos following the induction of audiogenic seizures in adult rats with transient neonatal hypothyroidism. The rats treated with 0.02% propylthiouracil (PTU) through mother's milk during days 0-19 after delivery showed a high incidence of seizures to auditory stimulation at the age of 4 months. The significant induction of c-fos mRNA by audiogenic seizures is prominent in several brain areas including central gray, peripeduncular nucleus, inferior colliculus, septal nucleus, bed nucleus of stria terminalis, and dorsomedial hypothalamus. However, the expression of c-fos mRNA was comparable in neocortex, dorsal hippocampus and medial geniculate body between control rats and PTU-treated, seizure-induced rats. These results confirm the previous report on the c-fos expression following audiogenic seizure sensitized during development by a loud noise [20]. The present results indicate that the neonatal PTU treatment may provide a useful tool for studying the mechanism underlying the seizure susceptibility and development after maturation.

Acoustic Stimulation↗
PubMed1996

Comparison of DNA fingerprinting by PFGE and PCR-RFLP of the coagulase gene to distinguish MRSA isolates.

Staphylococcus aureus isolates were collected from epidemiologically unrelated clinical sources in Japan between 1991 and 1993. A total of 40 isolates, five each of eight coagulase types, were analysed by polymerase chain reaction (PCR) of the coagulase gene, PCR-restriction fragment length polymorphism (RFLP) after AluI digestion, and pulsed-field gel electrophoresis (PFGE) of chromosomal DNA after SmaI digestion. The efficiency of discrimination among the isolates increased in the order of PCR < PCR-RFLP < PFGE, yielding five, 13 and 31 different types, respectively. To assess the clinical use of these methods, 42 additional methicillin-resistant S. aureus (MRSA) isolates collected from 27 inpatients in a hospital were analysed. PFGE and PCR-RFLP were able to discriminate 11 and four types, respectively. PFGE analysis detected cross-infection between four postoperative patients in an intensive-care unit, and in six neonates in intensive care. We conclude that of the three methods tested, PFGE analysis currently allows the most effective discrimination of MRSA strains.

Bacterial Typing Techniques↗
PubMed1996

Antigenicity of hepatitis C virus envelope proteins expressed in Chinese hamster ovary cells.

A putative second envelope glycoprotein (E2) of hepatitis C virus (HCV) was constitutively produced in a Chinese hamster ovary cell line stably transformed with a plasmid expressing E2 protein under the control of an exogenous promoter and a signal sequence. E2 protein that lacked part of the C-terminal hydrophobic region was glycosylated with high-mannose type oligosaccharides and retained in the cells. On the other hand, E2 protein lacking the entire C-terminal hydrophobic region was glycosylated with complex type oligosaccharides (complex form) and excreted into the culture medium. Immunoreactivity of the high-mannose and complex forms of E2 proteins against sera from HCV infected patients were analyzed. We found that the antigenicity of the complex form of E2 protein was greater than that of the high-mannose form of E2 protein. This result indicated that the complex form of the E2 protein is superior for use in diagnosing HCV infection.

Animals↗
PubMed1996

Two stage genome-wide search in inflammatory bowel disease provides evidence for susceptibility loci on chromosomes 3, 7 and 12.

Crohn's disease (CD) and ulcerative colitis (UC), the chronic inflammatory bowel diseases (CIBD), are common causes of gastro-intestinal disease in the Western world, with a combined prevalence of 100-200/100,000 (ref. 1). Epidemiological studies, particularly concordance rates in twin pairs and siblings, strongly implicate genetic susceptibility in the pathogenesis of CIBD. In fact, the relative contribution of genetic factors to the pathogenesis of CD may be greater than in schizophrenia, asthma or hypertension, and at least equivalent to that in insulin-dependent diabetes. Systematic screening of the entire human genome now provides a strategy for the identification of susceptibility genes in complex polygenic disorders. We undertook a two-stage genome search for susceptibility genes in inflammatory bowel disease involving 186 affected sibling pairs from 160 nuclear families. We provide strong evidence for the presence of susceptibility loci for both CD and UC on chromosome 3, 7 and 12. We obtained the highest lod score (5.47; P = 2.66 x 10(-7) with the marker D12S83 and lod scores of 3.08 and 2.69 for D7S669 and D3S1573, respectively. Our data suggest that CD and UC are closely related, but distinct, polygenic disorders that share some, but not all, susceptibility genes.

Chromosome Mapping↗
PubMed1996

Association of the tetraspan protein CD9 with integrins on the surface of S-16 Schwann cells.

The cell surface glycoprotein CD9 is a member of a group of proteins known as the "tetraspan" or "transmembrane 4 superfamily." Previous work with non-neural cells has shown that CD9 associates in cis with integrins and small GTP-binding proteins on the cell surface. To extend our recent findings showing that perturbation of CD9 alters Schwann cell adhesion, proliferation, and migration, as well as neurite outgrowth in sympathetic neurons, we have searched for CD9-associated proteins in S-16 Schwann cells. We demonstrate here that CD9 is specifically coprecipitated from S-16 cell extracts by antibodies against integrins alpha 3, alpha 6, and beta 1. In addition, double immunofluorescence labeling and co-capping experiments indicate that CD9 is specifically co-localized with these integrins on the cell membrane of S-16 Schwann cells.

Animals↗
PubMed1996

Quantitation of alpha-fetoprotein and albumin messenger RNA in human hepatocellular carcinoma.

To analyze gene expression of alpha-fetoprotein (AFP) and albumin in hepatocellular carcinoma (HCC), messenger RNAs (mRNAs) of these proteins in six human hepatoma cell lines and in 30 cases of HCC were quantitatively analyzed by competitive reverse transcription (RT) followed by polymerase chain reaction (PCR). The transcriptional levels of both AFP and albumin genes in HepG2 and Huh 7 cell lines were 10(10) copies/microgram RNA, in contrast to approximately 10(5) copies/microgram RNA in HLE and HLF cell lines. AFP and albumin mRNA levels in three normal livers were 10(5) and 10(10) transcripts/microgram RNA, respectively. In 30 cases with HCC AFP mRNA level in neoplasm was 10 to 10(5)-fold enhanced as compared with that of nonneoplastic portion, and correlated with serum AFP level and tumor size (P < .01). In contrast, albumin mRNA level was not reduced in the neoplasms presenting enhanced AFP mRNA levels, indicating that AFP and albumin gene expression in situ is not necessarily mutually exclusive. Prospective analysis revealed that an increased serum AFP was shown at the time of recurrence among patients with enhanced AFP mRNA levels in neoplasm only, indicating that AFP mRNA levels in neoplasm could be a clinically predictable tool.

Aged↗
PubMed1996

The absence of Pmp47, a putative yeast peroxisomal transporter, causes a defect in transport and folding of a specific matrix enzyme.

Candida boidinii Pmp47, an integral peroxisomal membrane protein, belongs to a family of mitochondrial solute transporters (e.g., ATP/ADP exchanger), and is the only known peroxisomal member of this family. However, its physiological and biochemical functions have been unrevealed because of the difficulties in the molecular genetics of C. boidinii. In this study, we first isolated the PMP47 gene, which was the single gene encoding for Pmp47 in a gene-engineerable strain S2 of C. boidinii. Sequence analysis revealed that it was very similar to PMP47A and PMP47B genes from a polyploidal C. Boidinii strain (ATCC32195). Next, the PMP47 gene was disrupted and the disruption strain (pmp47delta) was analyzed. Depletion of PMP47 from strain S2 resulted in a retarded growth on oleate and a complete loss of growth on methanol. Both growth substrates require peroxisomal metabolism. EM observations revealed the presence of peroxisomes in methanol- and oleate-induced cells of pmp47delta, but in reduced numbers, and the presence of material of high electron density in the cytoplasm in both cases. Methanol-induced cells of pmp47delta were investigated in detail. The activity of one of the methanol-induced peroxisome matrix enzymes, dihydroxyacetone synthase (DHAS), was not detected in pmp47delta. Further biochemical and immunocytochemical experiments revealed that the DHAS protein aggregated in the cytoplasm as an inclusion body, while two other peroxisome matrix enzymes, alcohol oxidase (AOD) and catalase, were active and found in peroxisomes. Two peroxisome-deficient mutants, strains M6 and M13 (described in previous studies), retained DHAS activity although it was mislocalized to the cytoplasm and the nucleus. We disrupted PMP47 in these peroxisome-deficient mutants. In both strains, M6-pmp47delta and M13-pmp47delta, DHAS was enzymatically active and was located in the cytoplasm and the nucleus. We suggest that an unknown small molecule, which PMP47 transports, is necessary for the folding or the translocation machinery of DHAS within peroxisomes. Pmp47 does not catalyze folding directly because active DHAS is observed in the M6-pmp47delta and M13-pmp47delta strains. Since both AOD and DHAS have the PTS1 motif sequences at their carboxyl terminal, our results first show that depletion of Pmp47 could dissect the peroxisomal import pathway (PTS1 pathway) of these proteins.

Alcohol Oxidoreductases↗
PubMed1996

Vaginal microflora associated with bacterial vaginosis in Japanese and Thai pregnant women.

The vaginal flora of 118 Japanese and 208 Thai pregnant women were investigated for the presence of bacterial vaginosis (BV), BV-associated organisms, and BV-associated enzyme. A similar prevalence of BV was found among the Japanese (13.6%) and Thai women (15.9%). The microbial flora of women with BV were complex; the mean number of isolates recovered in the BV group was approximately 2 times more than that in a group of healthy women. Prevotella species, Porphyromonas species, Peptostreptococcus species, Mobiluncus species, Gardnerella vaginalis, and H2O2-nonproducing lactobacilli were significantly associated with BV. These organisms were less associated with H2O2-producing lactobacilli, which were predominant in women with normal flora, suggesting that H2O2-producing lactobacilli have antibacterial activity against BV-associated organisms. The vaginal sialidase assay by means of a filter-paper spot test was not proved to be a useful screening aid for diagnosis of BV because of the low sensitivity (69.4%) of this test.

Adolescent↗
PubMed1996

Comparison of in vitro activities of DU-6859a and other fluoroquinolones against Japanese isolates of anaerobic bacteria.

The in vitro activity of DU-6859a, a new fluoroquinolone, was compared with those of other fluoroquinolones against clinical isolates of anaerobic bacteria and Gardnerella vaginalis. DU-6859a was the most active agent; it inhibited 90% of isolates of almost all species tested, including Bacteroides fragilis at < or = 0.39 micrograms/mL. Although the other quinolones tested were active against gram-positive anaerobes, inhibiting their growth at < or = 1.56 micrograms/mL, these agents were less active against the B. fragilis group and Prevotella bivia (90% of which were inhibited at > or = 6.25 micrograms/mL). Mobiluncus species and G. vaginalis, which are well associated with bacterial vaginosis, were inhibited by DU-6859a at 0.1 microgram/mL. These results suggest that DU-6859a is a promising oral agent for the treatment of bacterial infections due to anaerobic bacteria; however, further studies, including determination of vaginal levels of this compound, should be performed to study the role of DU-6859a in the treatment of bacterial vaginosis.

Administration, Oral↗
PubMed1996

Association of enterotoxigenic Bacteroides fragilis with bacteremia.

Polymerase chain reaction (PCR) assay was compared with cell culture assay performed with use of HT29/C1 (human colonic epithelial) cells for identifying strains of enterotoxin-producing Bacteroides fragilis (ETBF) isolated from extraintestinal specimens. A total of 188 unselected strains obtained over 2 years at a central clinical laboratory in Tokyo were tested. Overall, 35 strains (18.6%) were positive by cell culture and PCR assay, 152 strains were negative by both assays, and 1 strain was negative by cell culture assay but positive by the PCR assay; the same results were obtained in repeated assays. Among 64 strains from blood, 18 (28.1%) were ETBF, a rate that was significantly higher (P < .05) than the 17 ETBF (13.7%) among 124 strains from other sites. These results suggest that PCR assay is a simple and reliable tool for detecting ETBF and that enterotoxin may be a virulence factor in bacteremia caused by B. fragilis.

Bacteremia↗
PubMed1996

Feeding rats the nitric oxide synthase inhibitor, L-N(omega)nitroarginine, elevates serum triglyceride and cholesterol and lowers hepatic fatty acid oxidation.

This study was conducted to examine whether nitric oxide regulates lipid metabolism. In Experiment 1, rats were fed for 5 wk diets with or without 0.2 g/kg L-N-nitroarginine (L-NNA), a specific inhibitor of nitric oxide synthase, that were or were not supplemented with 40 g/kg L-arginine. Rats fed L-NNA had significantly higher concentrations of serum triglyceride and total cholesterol, lower concentrations of serum nitrate, and a lower ratio of HDL-cholesterol to total cholesterol than rats fed the basal diet. These alterations were suppressed by supplementing L-arginine to the L-NNA-containing diet. In Experiment 2, rats were fed diets with or without 0.2 g/kg L-NNA. Dietary L-NNA elevated serum concentrations of free fatty acids without affecting those of ketone bodies. L-NNA lowered the activity of hepatic carnitine palmitoyltransferase, the rate-limiting enzyme of fatty acid oxidation, but did not affect activities of hepatic glucose-6-phosphate dehydrogenase and fatty acid synthase which are lipogenic enzymes. These results suggest that the lower nitric oxide level in rats fed L-NNA leads to hyperlipidemia and that the elevation in serum triglyceride might be due to reduced fatty acid oxidation.

Animals↗