Biomedical subjects

K Yamamura

Publications and source records attributed to K Yamamura.

At least 91 records · Page 5Linked to original sources

PubMed1998

Zinc suppresses apoptosis of U937 cells induced by hydrogen peroxide through an increase of the Bcl-2/Bax ratio.

Treatment of human premonocytic U937 cells with 500 microM H2O2 for 1h followed by 4h incubation in fresh medium to allow the cells to execute apoptotic processes caused DNA fragmentation. However, in the presence of 1mM ZnSO4 throughout the incubation, DNA ladder formation was markedly inhibited. Hydrogen peroxide treatment for 1h with or without zinc increased both Bcl-2 and Bax proteins. However, only Bax protein decreased to basal levels in the presence of zinc during the following 4h incubation, resulting in an increase of the Bcl-2/Bax ratio and prevention of apoptosis. Treatment of U937 cells with 1mM ZnSO4 alone also decreased the levels of Bax protein. Furthermore, we observed that zinc completely inhibited the activation of CPP32 by H2O2, while no significant changes of ICE activities occurred with either H2O2 and/or zinc. These results indicate that the suppression of H2O2-induced apoptosis by zinc is mediated through an increase of the Bcl-2/Bax ratio, which occurs upstream from the activation of CPP32.

Apoptosis↗

PubMed1998

Bisecting GlcNAc structure is implicated in suppression of stroma-dependent haemopoiesis in transgenic mice expressing N-acetylglucosaminyltransferase III.

Several sugar structures have been reported to be necessary for haemopoiesis. We analysed the haematological phenotypes of transgenic mice expressing beta-1,4 N-acetylglucosaminyltransferase III (GnT-III), which forms bisecting N-acetylglucosamine on asparagine-linked oligosaccharides. In the transgenic mice, the GnT-III activity was elevated in bone marrow, spleen and peripheral blood and in isolated mononuclear cells from these tissues, whereas no activity was found in these tissues of wild-type mice. Stromal cells after long-term cultures of transgenic-derived bone marrow and spleen cells also showed elevated GnT-III activity, compared with an undetectable activity in wild-type stromal cells. As judged by HPLC analysis, lectin blotting and lectin cytotoxicity assay, bisecting GlcNAc residues were increased on both blood cells and stromal cells from bone marrow and spleen in transgenic mice. The transgenic mice displayed spleen atrophy, hypocellular bone marrow and pancytopenia. Bone marrow cells and spleen cells from transgenic mice produced fewer haemopoietic colonies. After lethal irradiation followed by bone marrow transplantation, transgenic recipient mice showed pancytopenia compared with wild-type recipient mice. Bone marrow cells from transgenic donors gave haematological reconstitution at the same level as wild-type donor cells. In addition, non-adherent cell production was decreased in long-term bone marrow cell cultures of transgenic mice. Collectively these results indicate that the stroma-supported haemopoiesis is compromised in transgenic mice expressing GnT-III, providing the first demonstration that the N-glycans have some significant roles in stroma-dependent haemopoiesis.

Acetylglucosamine↗

PubMed1998

Analysis of the murine Hoxa-9 cDNA: an alternatively spliced transcript encodes a truncated protein lacking the homeodomain.

Hoxa-9 is one of the homeo box (Hox) genes exhibiting similarity to the Drosophila Abdominal B gene. So far, only partial nucleotide sequences have been reported for mouse Hoxa-9 cDNA (Rubin et al., (1987) Mol. Cell. Biol. 7, 3836-3841). Here, we have determined the nucleotide sequence of the 5'-region of mouse Hoxa-9 cDNA and its genomic structure. Mouse Hoxa-9 cDNA contains a complete ORF encoding a protein of 271aa exhibiting 96.7% identity to its human counterpart. Interestingly, an alternatively spliced transcript (Hoxa-9T) was identified by RT-PCR. Sequence analysis revealed that 173bp within the Hoxa-9 ORF was missing from the Hoxa-9T cDNA. This additional splicing would potentially result in a frameshift, leading to the production of a truncated protein lacking the homeobox. Northern blot analysis revealed that the probe containing the homeodomain hybridized to two major transcripts (2.5 and 1.9kb) in the trunk region of 12.5 dpc embryos, and adult kidney and large intestine. On the other hand, the probe containing the additional intron detected only 2.5kb transcript in the same tissues, indicating that 1.9kb transcript corresponds to Hoxa-9T mRNA. We have also determined the transcriptional start site of Hoxa-9T.

Alternative Splicing↗

PubMed1998

Concentration-dependent differential effects of N-acetyl-L-cysteine on the expression of HSP70 and metallothionein genes induced by cadmium in human amniotic cells.

Cadmium induces the expression of the 70 kDa heat shock protein (HSP70) and metallothionein (MT), both of which are considered to be associated with intracellular glutathione (GSH) metabolism in the cellular protection mechanism against cadmium-induced cellular injury. We determined the effects of N-acetyl-L-cysteine (NAC), which increases the intracellular GSH levels, on the induction of HSP70 and MT gene expression in a cultured cell line of human amniotic cells (WISH) exposed to CdCl2. The mRNA level of MT-II, a major isoform of MT genes, was more prominently increased than that of HSP70 when WISH cells were exposed to CdCl2 (5-15 microM, for 6 h). The treatment of WISH cells with 1.5 and 30 mM NAC for 2 h increased the intracellular GSH levels by 1.4- and 3.1-fold, respectively. Pretreatment of cells with 30 mM NAC significantly reduced both HSP70 and MT-II mRNA levels in the cells exposed to 50 microM CdCl2. This concentration of NAC also efficiently suppressed the cadmium-induced lethality. On the contrary, pretreatment with 1.5 mM NAC suppressed only the induction of HSP70 gene expression in the 50 microM CdCl2-treated cells, and did not inhibit the metal toxicity. However, this low concentration of NAC efficiently suppressed lipid peroxidation which was increased by 50 microM CdCl2. Furthermore, this low concentration of NAC also decreased the CdCl2-induced gene expression of HSP32 which represents a general response to oxidative stress. Taken together, NAC seems to have at least two concentration-dependent functions in WISH cells exposed to CdCl2; the low concentration of NAC can suppress the induction of HSP70 gene expression as well as the increase of lipid peroxidation via an antioxidant pathway, while the high concentration of NAC can suppress the induction of MT-II mRNA as well as cadmium-induced cell death. Our present data suggest that changes in intracellular redox status, as reflected by GSH concentration, have more important effects on the induction of HSP70 mRNA rather than that of MT-II mRNA in human amniotic cells exposed to cadmium.

Acetylcysteine↗

PubMed1998

Ectopic expression of N-acetylglucosaminyltransferase III in transgenic hepatocytes disrupts apolipoprotein B secretion and induces aberrant cellular morphology with lipid storage.

N-Acetylglucosaminyltransferase III (GnT-III) produces "bisecting-GlcNAc" and regulates the branching of N-glycans. GnT-III activity is elevated during hepatocarcinogenesis, which is in contrast to the undetectable level found in normal hepatocytes. To determine the biological significance of GnT-III in hepatocytes, transgenic mice that specifically express GnT-III in the liver were established and characterized. The transgenic hepatocytes had a swollen oval-like morphology, with many lipid droplets. Apolipoprotein B, which contained increased level of bisecting-GlcNAc accumulated in the transgenic hepatocytes. In the transgenic serum, triglycerides, the beta- and pre-beta-lipoprotein fractions, and apolipoprotein B100 were significantly decreased, compared with levels in nontransgenic serum. These abnormal phenotypes were more prominent in the mice with more copies of the transgene and a resulting high GnT-III activity. We demonstrate that aberrant glycosylation, as the direct result of the formation of bisecting-GlcNAc, disrupts the function of apolipoprotein B, leading to the generation of fatty liver. This observation suggests a novel mechanism for the pathogenesis of fatty liver.

Animals↗

PubMed1998

A null mutation in basigin, an immunoglobulin superfamily member, indicates its important roles in peri-implantation development and spermatogenesis.

Basigin is a highly glycosylated transmembrane protein with two immunoglobulin-like domains. We generated mutant mice lacking the basigin gene (Bsg) by gene targeting. Bsg (-/-) embryos developed normally during preimplantation stages. However, the majority of Bsg (-/-) embryos died around the time of implantation. At this time, basigin mRNA was strongly expressed in the trophectoderm, embryo proper, and uterine endometrium of Bsg (+/+) mice. These results suggest that basigin is involved in intercellular recognition during implantation. Embryos which survived the critical period yielded Bsg (-/-) mutant mice. Half of the mutant mice died before 1 month after birth, due to interstitial pneumonia. The surviving adult mutant mice were small and sterile. Spermatogenesis was arrested in the mutant mice. Most of the spermatocytes in the Bsg (-/-) mouse were arrested and degenerated at the metaphase of the first meiosis, and only a small number differentiated to step 1 spermatids. In the female mutants, the ovaries and genital tract were morphologically normal, and the defect was probably in the capability of implantation of the uterus. In conclusion, basigin is an important cell-surface molecule involved in early embryogenesis and reproduction.

Animals↗

PubMed1998

Oral mucosal adhesive film containing local anesthetics: in vitro and clinical evaluation.

In vitro and in vivo studies were conducted to gauge the effectiveness of a novel oral mucosa adhesive, moderately water-soluble, pliant polymer artificial dentifrice (AD) film containing dibucaine (DC) for relief of pain due to oral erosion. The film was prepared from a hydroxypropyl cellulose-M (HPC-M) ethanol solution containing varying amounts of DC, as well as polyethylene glycol. In the in vitro experiments, the disintegration of HPC-M showed a lag time of about 50 min, a much lower rate than that of drug release, which more or less leveled off after 50 min. Twenty-five percent of the DC was released from the film (0.113 and 0.225 mg/cm2) after the initial 5 min, which then reached about 80% after 50 min, the time at which the polymer began to break up. In the in vivo study, the local anesthetic effect of the film was evaluated in 23 patients (10 males, 13 females) suffering from the adverse effects of chemotherapy. When applied to the wet surface of the mucosa, the AD film absorbed moisture and showed excellent adhesion. Pain relief in patients lasted 2.2 +/- 0.21 and 4.3 +/- 0.25 h at DC doses of 0.113 and 0.225 mg/cm2, respectively. These results suggest that the AD film may cover mucositis sites of oral mucosa long enough to allow DC release and bring relief from pain arising from chemotherapy and/or radiotherapy.

Adhesives↗

PubMed1998

Tctex3, related to Drosophila polycomblike, is expressed in male germ cells and mapped to the mouse t-complex.

Tctex3 showing restricted expression in male germ cells has been isolated during the process of chromosome walking in the mouse t-complex region. The total sequence of Tctex3 cDNA predicts a protein of 580 amino acids with two C4HC3 type PHD fingers. The region containing this conserved motif is shared among members of the Polycomblike proteins that include the mouse M96 and Drosophila Polycomblike. A partial cDNA for a human homolog of Tctex3, HUTEX3, has also been isolated. Mouse Tctex3 gene was mapped adjacent to Tsc2 gene on mouse Chromosome (Chr) 17, and HUTEX3 was located closely to HSET gene in the HLA class II region of chromosome 6.

Amino Acid Sequence↗

PubMed1998

Region-specific expression of murine Hox genes implies the Hox code-mediated patterning of the digestive tract.

BACKGROUND: Hox genes encode transcription factors which are involved in the establishment of regional identities along the anteroposterior (AP) body axis. To elucidate the AP patterning of the digestive tract, we have systematically examined the expression patterns of Hox genes belonging to paralogue groups 6, 7, 8 and 9 by whole-mount in situ hybridization and by section in situ hybridization analyses. RESULTS: The expression patterns of these genes showed co-linearity along the wall of the digestive tract, thereby yielding the Hox code of the gut. The expression boundaries of the Hox genes at later stages (12.5 d.p.c.) corresponded to the morphological boundaries of individual gut subdomains. CONCLUSIONS: The visceral mesoderm-restricted expression suggested that the Hox code primarily functions in the mesenchymal specification which eventually leads to the regional differentiation of gut subdomains as the result of epithelial-mesenchymal interactions. Overlapping expression patterns were found among the paralogous Hox genes, indicating that the paralogues may have redundant functions in the specification of the gut.

Animals↗

PubMed1998

Experimental study on the effects of gentamicin injection on the guinea-pig: electrophysiological studies.

The inner ear distortion induced by gentamicin (GM), a type of aminoglycoside antibiotic, was examined in guinea-pigs. Previous studies which investigated the function of the eighth cranial nerve and organ of Corti using cochlear microphonics (CM) and compound action potential (CAP) reported ototoxicity following experimental exposure to GM. In this report, the effects of GM on the cochlea and the eighth cranial nerve were investigated systematically by measuring CM, CAP, summating potentials induced by 90 dB (SPL) tone burst, endocochlear potential (EP) and K+ ion concentration of the endolymph. Guinea-pigs were treated with a daily intramuscular injection of GM (60 mg in 1.5 cc) at a dose of 60 mg/kg during different treatment periods. The maximum output voltage of AP was decreased by injection of GM (60 mg/kg x 24). A decrease in the CM maximum output voltage and the elevation of CM pseudothreshold were typically seen after GM injection at a test frequency of 8 kHz and a decrease in CAP was also observed. Changes in EP during 3 min anoxia were observed, in particular a decrease in the absolute value of the negative potential. The endolymph K+ ion concentration remained unchanged. These findings indicate that the diffusion potentials decreased at the same time as reduction of maximum output voltage in CM induced by GM injection.

Action Potentials↗

PubMed1998

Mouse chondroitin 6-sulfotransferase: molecular cloning, characterization and chromosomal mapping.

Chondroitin 6-sulfotransferase (C6ST) catalyzes the transfer of sulfate from 3'-phosphoadenosine 5'-phosphosulfate to position 6 of the N-acetylgalactosamine residue of chondroitin. Using chick C6ST cDNA as a probe, we cloned the cDNA of mouse C6ST. The mouse enzyme was predicted to be composed of 472 amino acids, and exhibited 71% sequence identity with the chicken enzyme. The mouse and chicken catalytic domains exposed to the luminal side exhibited 81% identity, while the homology of the remaining regions was less. Transfection and expression of the mouse cDNA in COS-7 cells yielded C6ST activity. Keratan sulfate sulfotransferase activity, which was simultaneously expressed, amounted to 3% of the C6ST activity, this value being significantly lower than that observed in the case of the chicken enzyme. Mouse C6ST mRNA was strongly expressed in the spleen, lung, and eye. In situ hybridization revealed that the transcript was localized in stromal cells in the marginal zone and red pulp of the spleen, and stromal cells in the bone marrow. Fluorescence in situ hybridization analysis revealed the gene is located in mouse chromosome 9.

Amino Acid Sequence↗

PubMed1998

Human N-acetylglucosamine-6-O-sulfotransferase involved in the biosynthesis of 6-sulfo sialyl Lewis X: molecular cloning, chromosomal mapping, and expression in various organs and tumor cells.

N-Acetylglucosamine-6-O-sulfotransferase catalyzes the transfer of sulfate from 3'-phosphoadenosine 5'-phosphosulfate to position 6 of a non-reducing N-acetylglucosamine (GlcNAc) residue. We have cloned human GlcNAc-6-O-sulfotransferase cDNA, based on the sequence homology to cloned cDNA of mouse GlcNAc-6-O-sulfotransferase. The predicted protein sequence of the human enzyme was highly homologous to that of the mouse enzyme; in the 363 amino acid stretch of the catalytic region, the two proteins were nearly identical except for conservative changes in 3 amino acid residues. The expressed enzyme transferred sulfate to GlcNAcbeta1-3Galbeta1-4GlcNAcbeta1-3Galbeta1-4Gl cNAc. Co-transfection of the enzyme cDNA and fucosyltransferase VII cDNA into COS-7 cells resulted in cell surface expression of 6-sulfo sialyl Lewis X. Fluorescence in situ hybridization analysis revealed that the GlcNAc-6-O-sulfotransferase gene is located on human chromosome 7q31. mRNA of the human enzyme was strongly expressed in the bone marrow, peripheral blood leukocytes, spleen, brain, spinal cord, ovary, and placenta, and moderate levels of expression were observed in many organs including lymph nodes and thymus. In situ hybridization with the mouse system showed that the transcript was localized in specific regions of the brain, i.e. pyramidal cells in the CA3 subregion of the hippocampus, cerebellar nucleus and Purkinje cells. Among human tumor cells, strong expression of the mRNA was found in MOLT-4 and Jarkat lymphoblastic leukemia cells, Raji lymphoma cells, K-562 chronic myelogeneous leukemia cells, U251 glioma cells, and G361 melanoma cells. Carbohydrate structures synthesized by the sulfotransferase may be involved in various aspects of the differentiation and behavior of blood cells, their progenitor cells, and neurons in the central nervous system.

Amino Acid Sequence↗

PubMed1998

Transgenic mouse expressing a full-length hepatitis C virus cDNA.

Hepatitis C virus (HCV), a major causative agent of post transfusion non-A, non-B hepatitis (NANBH), can only infect humans and chimpanzees. We produced nine transgenic mouse lines carrying a full-length HCV cDNA with the human serum amyloid P component (hSAP) promoter that can direct liver-specific expression. In one of these lines HCV mRNA and HCV core protein were detected in the liver of the transgenic mouse, although the levels of expression were very low. In addition, HCV-related antibody was detected in the serum.

Alanine Transaminase↗

PubMed1998

Different responses other than the formation of DNA-adducts between the livers of carcinogen-resistant rats (DRH) and carcinogen-sensitive rats (Donryu) to 3'-methyl-4-dimethylaminoazobenzene administration.

Carcinogen-resistant inbred DRH rats developed from the Donryu strain showed a remarkably low incidence of liver tumors when they were fed diets containing hepatocarcinogens such as 3'-methyl-4-dimethylaminoazobenzene (3'-Me-DAB). In this work, we examined various characteristics of male DRH and Donryu rats during 3'-Me-DAB administration for 8 weeks. 32P-Postlabeling analysis showed that essentially similar levels of DNA-adducts were generated by the metabolites of 3'-Me-DAB in the livers of these two strains of rats at several time points. However, both GADD45 (growth arrest and DNA damage-inducible) and O6-methylguanine methyltransferase (putatively DNA damage-inducible) mRNA levels were increased significantly in Donryu rat livers, but were increased to a lesser extent in DRH rats. [3H]Thymidine incorporation into hepatic DNA began to increase around 10 to 20 days after the start of 3'-Me-DAB administration in Donryu rats probably due to DNA repair, while no significant change occurred in DRH rats under the same conditions. Furthermore, inductions of heme oxygenase (due to degradation of heme-proteins) and hepatocyte growth factor (HGF; cell death and regeneration of hepatocytes) mRNAs were greater in Donryu rat livers than those of DRH, suggesting that the former were more sensitive to cytotoxic effects of 3'-Me-DAB than the latter. Another remarkable difference observed between these two strains was the significant induction of cytochrome P-450 2E1 mRNA in Donryu rat livers; this may contribute to the generation of reactive oxygen intermediates. Finally, increases of glutathione S-transferase (P-form) and gamma-glutamyltranspeptidase mRNAs as marker enzymes of preneoplastic changes of hepatocytes were clearly seen only in Donryu rat livers at 6 to 8 weeks after the start of 3'-Me-DAB administration. These results indicate that the different susceptibility to hepatocarcinogenesis between these two strains of rats may arise from events other than the DNA adduct formation.

Animals↗

PubMed1998

Induction of tumor necrosis factor-alpha mRNA in the kidney of the mouse chronic hepatitis model.

Previously we reported the induction of tumor necrosis factor (TNF)-alpha mRNA in the liver of interferon (IFN)-gamma transgenic mouse, which might be the result of IFN-gamma gene expression. In the present study, IFN-gamma mRNA was induced in the liver, kidney and lung. TNF-alpha mRNA was, however, induced in the liver and kidney, but not in the lung. Induction of interleukin (IL)-2 and IL-1beta mRNA was lacking in any of these organs. The present result showed the induction of TNF-alpha mRNA expression in the kidney of transgenic mouse.

Animals↗

PubMed1998

Induction of Fas ligand and Fas antigen mRNA expressions in interferon-gamma transgenic mouse liver.

The interferon-gamma (IFN-gamma) transgenic mouse develops chronic hepatitis. In the present study, lymphoid cell infiltration and expression of the Fas system were studied in the transgenic mouse liver. Morphological analysis showed the infiltration of lymphoid cells at the portal area and necro-inflammation in the lobules. Furthermore, the infiltrating lymphoid cells were found to be present in the areas of piecemeal necrosis and the intralobular region. The polymerase chain reaction revealed induction of Fas antigen and Fas ligand mRNA expressions. The chronic hepatitis in this mouse reflects the profiles of human chronic hepatitis.

Alanine Transaminase↗

PubMed1998

[Nutritional intake by the oldest elderly Japanese. Tokyo Centenarian Study 6].

Rapid demographic aging has made caring for the elderly an increasingly important social issue in Japan. To study current conditions of the oldest elderly citizens, we investigated the dietary practices of centenarians in the Tokyo metropolitan area. First, we compared the food intake of centenarians with that of octogenarians. Next, to identify dietary trends, we investigated whether food intake by centenarians had changed significantly between 1981 and 1995. Nutritional intake by the centenarians and octogenarians in 1995 was about 60% and 75% that of the control, respectively. However, the nutritional intake of well nourished centenarians was similar to that of the octogenarians. Cognitive function and daily activity have an influence on nutritional intake. The centenarians were similar to the control subjects in their consumption of dairy products, sweets, and fruit. However, their intake of cereals, meat, fish, and fatty oils was loss than 60% that of the control, which indicates their preference for soft and sugary foods. The pattern of dietary practices of centenarians in 1981 was similar. Although the total food intake of centenarians amounted to 60% of the control in 1995 energy intake per kilogram of body weight averaged over 30 kcal. As to dietary trends, centenarians in 1981 are more cereals, eggs, algae products, and legumes than did their 1995 counterparts. This finding seems to reflect a generational difference in dietary habits.

Activities of Daily Living↗

PubMed1998

Iontophoretic application of prostaglandin E1 for improvement in peripheral microcirculation.

OBJECTIVE: The pharmacological effects of iontophoretically applied prostaglandin E1 (PGE1) on the peripheral microcirculation were investigated. MATERIAL AND METHOD: PGE1 concentrations permeated through hairless mouse skin iontophoretically were measured by HPLC at hourly intervals. 19 patients with arteriosclerosis obliterans were given PGE1 (20 microg) iontophoretically on the dorsum of the foot. As a control, normal saline was applied iontophoretically on another day. The increase rate in cutaneous blood flow as measured by laser Doppler flux (LDF) level was investigated. 5 of these 19 patients received PGE1 (20 microg) solution intravenously on another day. The increase rate in cutaneous blood flow as measured by laser Doppler flux (LDF) level was compared between iontophoresis and intravenous drip infusion. RESULT: PGE1 was transported across hairless mouse skin with iontophoresis in a time-dependent manner, while it did not permeate by passive transport. The percent increase in LDF level was significantly higher in the PGE1 group than in the control group(32.7+/-20.2% vs. 10.3+/-15.5%, p.001). The percentual increase in LDF level was significantly higher with iontophoresis than with intravenous drip infusion (43.7+/-19.5% vs. 11.7+/-28.3%, p < 0.05). CONCLUSION: The results indicated that iontophoretically applied PGE1 was effective in improving the impaired microcirculation due to peripheral arterial occlusive disease. This technique may be useful in managing severely ischemic legs.

Alprostadil↗