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R Hirata

Publications and source records attributed to R Hirata.

At least 55 records · Page 3Linked to original sources
PubMed1992

Genetic and cell biological aspects of the yeast vacuolar H(+)-ATPase.

The yeast vacuolar proton-translocating ATPase is a member of the third class of H(+)-pumping ATPase. A family of this type of H(+)-ATPase is now known to be ubiquitously distributed in eukaryotic vacuo-lysosomal organelles and archaebacteria. Nine VMA genes that are indispensable for expression of the enzyme activity have been cloned and characterized in the yeast Saccharomyces cerevisiae. This review summarizes currently available information on the VMA genes and cell biological functions of the VMA gene products.

Proton-Translocating ATPases↗
PubMed1992

Molecular genetics of the yeast vacuolar H(+)-ATPase.

The yeast vacuolar proton-translocating ATPase was discovered in 1981 as the first member of the V-ATPases, which are now known to be ubiquitously distributed in eukaryotic vacuo-lysosomal organelles and archaebacteria. Nine VMA genes that are indispensable for expression of vacuolar ATPase activity have been identified in the yeast Saccharomyces cerevisiae. VMA1, VMA2, VMA3, VMA5 and VMA6 were cloned and characterized on the basis of partial amino acid sequences determined with the purified subunits. Genetic and biochemical studies of the yeast Pet-cls mutants have demonstrated that they are related to vma defects. Based on this evidence, VMA11 (CLS9), VMA12 (CLS10) and VMA13 (CLS11) were isolated from a yeast genomic DNA library by complementation of the vma11, vma12 and vma13 mutations, respectively. This article summarizes currently available information on the VMA genes and the molecular biological functions of the VMA gene products.

Adenosine Triphosphatases↗
PubMed1992

The effect of phlebotomy on serum erythropoietin levels in normal healthy subjects.

We evaluated endogenous serum erythropoietin (Epo) levels in 14 normal subjects (eight males and six females) after a single 400-ml phlebotomy. The subjects were followed up for 56 days. The hemoglobin (Hb) values of both males and females decreased to a nadir on days 3 to 7 post-phlebotomy. Hb values gradually increased, but did not completely recover to pre-phlebotomy levels by day 56. Serum Epo levels increased after 6 h post-phlebotomy, to 20.1 +/- 5.4 (mU/ml) in males and 20.7 +/- 7.0 in females, from the pre-phlebotomy levels of 14.6 +/- 4.0 in males and 13.4 +/- 4.1 in females, respectively. Epo levels continued to increase to peak levels of 25.5 +/- 6.3 in males and 28.7 +/- 11.5 in females on days 7 to 14 and thereafter decreased until day 56. Thus, the Epo response to a 400-ml phlebotomy was relatively small in magnitude and was not sufficient to initiate a significant increase in erythropoiesis. This finding suggests that the administration of recombinant human erythropoietin (rHu-Epo) may be effective for the prompt correction of anemia induced by autologous blood donation and for increasing the volume of predonated autologous blood.

Adult↗
PubMed1990

Roles of the VMA3 gene product, subunit c of the vacuolar membrane H(+)-ATPase on vacuolar acidification and protein transport. A study with VMA3-disrupted mutants of Saccharomyces cerevisiae.

VMA3, a structure gene of the vacuolar membrane H(+)-ATPase subunit c of Saccharomyces cerevisiae, has been cloned and characterized. The VMA3 gene encodes a hydrophobic polypeptide with 160 amino acids as reported previously by Nelson and Nelson (Nelson, H., and Nelson, N. (1989) FEBS Lett. 247, 147-153). Peptide sequence analysis indicated that the VMA3 gene product lacks N-terminal methionine and does not have a cleavable signal sequence. To investigate functional and structural roles of the subunit c for vacuolar acidification and protein transport to the vacuole, haploid mutants with the disrupted VMA3 gene were constructed. The vma3 mutants can grow in nutrient-enriched medium, but they have completely lost the vacuolar membrane H(+)-ATPase activity and the ability of vacuolar acidification in vivo. The subunit c was found to be indispensable for the assembly of subunits a and b of the H(+)-ATPase complex. The disruption of the VMA3 gene causes yeast cells with considerable lesions in vacuolar biogenesis and protein transport to the vacuole and inhibits endocytosis of lucifer yellow CH completely.

Anti-Bacterial Agents↗
PubMed1990

Molecular structure of a gene, VMA1, encoding the catalytic subunit of H(+)-translocating adenosine triphosphatase from vacuolar membranes of Saccharomyces cerevisiae.

Subunit a of the vacuolar membrane H(+)-translocating adenosine triphosphatase of the yeast Saccharomyces cerevisiae contains a catalytic site for ATP hydrolysis. N-terminal sequences of six tryptic peptides of the subunit were determined. Based on the peptide sequence information, a 39-base oligonucleotide probe was synthesized, and the gene encoding the subunit (VMA1) was isolated from a genomic DNA library by hybridization. The nucleotide sequence of the gene predicts a polypeptide of 1,071 amino acids with a calculated molecular mass of 118,635 daltons, which is much larger than the value 67 kDa estimated on sodium dodecyl sulfate-polyacrylamide gels. N- and C-terminal regions of the deduced sequence (residues 1-284 and 739-1,071) are very similar to those of the catalytic subunits of carrot (69 kDa) and Neurospora crassa (67 kDa) vacuolar membrane H(+)-ATPases (62 and 73% identity over 600 residues, respectively). The homologous regions also show about 25% sequence identity over 400 residues with beta-subunits of F0F1-ATPases. In contrast, the internal region containing 454 amino acid residues (residues 285-738) shows no detectable sequence similarities to any known ATPase subunits and instead is similar to a yeast endonuclease encoded by the HO gene. None of the six tryptic peptides is located in this internal region. Northern blotting analysis detected a single mRNA of 3.5 kilobases, indicating that the gene has no introns. Although the reason for the discrepancy in molecular mass is unclear at present, these results suggest that a novel processing mechanism, which might involve a post-translational excision of the internal region followed by peptide ligation, operates on the yeast VMA1 product. The VMA1 gene has proven to be the same gene as the TFP1 gene (Shih, C.-K., Wagner, R., Feinstein, S., Kanik-Ennulat, C., and Neff, N. (1988) Mol. Cell. Biol. 8, 3094-3103) whose dominant mutant allele (TFP1-408) confers a dominant trifluoperazine resistance and Ca2(+)-sensitive growth. This and our findings suggest that the vacuolar membrane H(+)-ATPase participates in maintenance of cytoplasmic Ca2+ homeostasis.

Amino Acid Sequence↗
PubMed1990

[Surgical results of high grade constriction of tricuspid annulus in DeVega technique for secondary tricuspid regurgitation].

Sixty-six patients were operated on by our high degree constriction technique using DeVega tricuspid annuloplasty from 1985 to 1989. They were 20 men and 46 women, age distributed from 28 to 71 (mean 54.5). Preoperative tricuspid annular diameter ranged from 29 mm to 45 mm, average 36.3 mm. Those were constricted to 27 mm in 38 patients, and to 25 mm in 28 patients. Postoperative residual tricuspid regurgitation was observed in only 8.5% of total cases followed up 14 to 55 months. This results were comparable with other reports. We concluded that our tight constriction DeVega method is considered better to prevent postoperative tricuspid regurgitation than ordinary methods.

Adult↗
PubMed1989

Functional molecular masses of vacuolar membrane H+-ATPase from Saccharomyces cerevisiae as studied by radiation inactivation analysis.

The functional molecular masses of the vacuolar membrane H+-ATPase in Saccharomyces cerevisiae under two kinetic conditions for ATP hydrolysis were measured by radiation inactivation. When vacuolar membrane vesicles were exposed to gamma-rays from 60Co, the activities catalyzing a single-cycle and multi-cycles of ATP hydrolysis both decreased as single-exponential functions of the radiation dosage. By applying the target theory, the functional molecular masses for single- and multi-cycle hydrolyses of ATP were determined to be approx. 0.9-1.1 X 10(5) and 4.1-5.3 X 10(5) Da, respectively. N,N'-Dicyclohexylcarbodiimide (DCCD) did not inhibit the former reaction but strongly inhibited the latter. It is suggested that the ATPase with a minimal composite of subunits a and b, in which subunit c is not necessarily involved operationally, can catalyze single-cycle hydrolysis of ATP, whereas for multi-cycle hydrolysis of ATP, the ATPase requires a properly organized oligomeric structure with subunits a-c, which may direct a positive cooperative mechanism of ATP hydrolysis and coupled H+ translocation in a DCCD-sensitive manner.

4-Chloro-7-nitrobenzofurazan↗
PubMed1989

Structure and function of the yeast vacuolar membrane proton ATPase.

Our current work on a vacuolar membrane proton ATPase in the yeast Saccharomyces cerevisiae has revealed that it is a third type of H+-translocating ATPase in the organism. A three-subunit ATPase, which has been purified to near homogeneity from vacuolar membrane vesicles, shares with the native, membrane-bound enzyme common enzymological properties of substrate specificities and inhibitor sensitivities and are clearly distinct from two established types of proton ATPase, the mitochondrial F0F1-type ATP synthase and the plasma membrane E1E2-type H+-ATPase. The vacuolar membrane H+-ATPase is composed of three major subunits, subunit a (Mr = 67 kDa), b (57 kDa), and c (20 kDa). Subunit a is the catalytic site and subunit c functions as a channel for proton translocation in the enzyme complex. The function of subunit b has not yet been identified. The functional molecular masses of the H+-ATPase under two kinetic conditions have been determined to be 0.9-1.1 x 10(5) daltons for single-cycle hydrolysis of ATP and 4.1-5.3 x 10(5) daltons for multicycle hydrolysis of ATP, respectively. N,N'-Dicyclohexyl-carbodiimide2 does not inhibit the former reaction but strongly inhibits the latter reaction. The kinetics of single-cycle hydrolysis of ATP indicates the formation of an enzyme-ATP complex and subsequent hydrolysis of the bound ATP to ADP and Pi at a 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole-sensitive catalytic site. Cloning of structural genes for the three subunits of the H+-ATPase (VMA1, VMA2, and VMA3) and their nucleotide sequence determination have been accomplished, which provide greater advantages for molecular biological studies on the structure-function relationship and biogenesis of the enzyme complex. Bioenergetic aspects of the vacuole as a main, acidic compartment ensuring ionic homeostasis in the cytosol have been described.

Cloning, Molecular↗
PubMed1989

[Predictive value of serum aminoterminal type III procollagen peptide levels, serum laminin levels, and liver membrane antibodies for prognosis of chronic hepatitis].

Serum concentration of aminoterminal type III procollagen peptide (P3P) and laminin have been shown as serum markers of liver fibrosis. In addition, liver membrane antibody (LMA) is suggested to play a role in the pathogenesis of chronic hepatitis. However, it is not known whether these serum markers are useful to predict the prognosis of chronic hepatitis. To test this, we measured P3P, laminin, and LMA in sera at the time of liver biopsies in 43 patients with chronic hepatitis who had serial liver biopsies more than two times during the 2-81 months (mean 25 months) follow-up period. Serum contents of P3P and laminin were measured by radioimmunoassay. Serum LMA was measured by radioimmunoassay according to the method of Thomas et al. The histological grading of liver fibrosis and of inflammation were scored according to Histology Activity Index by Knodell et al. Among thirty-two patients who had liver biopsies during 12-55 months, 16 patients showed histological progression on their latest liver biopsies compared with the first biopsies (Group 1). At the first biopsies, serum P3P levels were significantly higher in Group 1 than in 16 patients without histological progression (Group 2) (p less than 0.05). However, no difference were observed in serum laminin levels and in serum LMA between the two groups. Serum laminin levels were significantly correlated with the histological scores of fibrosis (comparison chisq = 0.0089, df = 2, p = 0.995584) and inflammation (comparison chisq = 21.4103, df = 4, p = 0.000263), respectively. In addition, serum P3P levels showed no correlation with the histological scores.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

[En-block bilateral lung transplantation: experiments in dogs].

En-block bilateral lung transplantation was performed in dogs according to methods introduced by Dark et al and Patterson et al. Under the extra-corporeal bypass the donor's trachea, atrium and pulmonary artery trunk were anastomosed to those of recipient, respectively. Five dogs receiving bilateral lung transplantation died after a short period survival because of hemodynamic insufficiency postoperatively. Although the aim of the experiment in this series was the follow-up trial of double lung transplantation, in consequence the poor prognoses were gained, we believe the long-term survival may be possible by the device skill in the technique.

Animals↗
PubMed1987

Differential prognosis detected by immunophenotyping in acute lymphoblastic leukemia of childhood with poor prognostic factors.

Immunological phenotypes of leukemic blasts from 50 children with acute lymphoblastic leukemia (ALL) have been examined with a panel of monoclonal antibodies to evaluate their prognostic significance. Thirty-seven of them were common-ALL positive for CD10 "common-ALL antigen (CALLA)" (NL-1), CD19(B4) and HLA-DR. One was pre-B ALL negative for CALLA and another null-ALL which expressed HLA-DR alone. Six of the remaining 11 cases were traditional T-ALL positive for CD2(9.6), and the other five tentative pre-T ALL positive for CD7(Tp40) but negative for CD2. Twenty-one out of 39 patients with non-T ALL were treated with the standard regimen. The 18 children with non-T ALL having poor prognostic factors, five with pre-T ALL and six with T-ALL were treated with the more intensive regimen. The median follow-up period was 36 (range 4 to 74) months. Their disease-free survival probabilities were compared. It was found that the disease-free survival of non-T ALL patients with poor prognostic factors was comparable to that of the patients without such factors as a result of the more intensive chemotherapy. Among the patients with poor prognostic factors, those with pre-T ALL as well as those with T-ALL, which were positive for CD7 antigen, were found to have significantly short disease-free survival times (P less than 0.03). CD7 antibody is most useful for detecting ALL patients with poor prognoses.

Antibodies, Monoclonal↗
PubMed1986

Molecular characterization of three HLA class II molecules on DR4 and DRw9 haplotypes: serologic and structural relationships at the polypeptides level.

By using alloantisera, three distinct HLA-D/DR region-encoded class II molecules were identified from cells carrying the HLA-DR4 and DRw9 haplotypes. Both DRw-53 and DQw3 molecules that bear the "supertypic" specificity were isolated independently from the DR antigen. The light chains of the DR4 antigens from different HLA-D types were distinct from one another, whereas the DRw53 molecules had identical charge and molecular weight in both heavy and light chains. On the other hand, the DQw3 molecules from the DR4 cell lines (Dw4 and Dw 10) were apparently identical but were polymorphic at least in the light chains among the DR4, DR5, and DRw9 haplotypes. In addition, monoclonal antibodies which specifically precipitate DR4 and DQw3 molecules have been isolated. The variable extent of homogeneity and diversity of three class II molecules may aid in our understanding of the role of class II antigens in the human immune regulation.

Antibodies, Monoclonal↗
PubMed1986

Multiple epitopes on a single DQ molecule from the DQw3-carrying haplotypes.

Multiple polymorphisms on the DQ molecule(s) have been detected by monoclonal antibodies (MoAbs). Among these, TA10 and IIB3 have been described as two new alleles in the DQ region other than the conventional DQw1-w3 allelism. The TA10 specificity is DQw3-related and is in linkage disequilibrium with DR5 and weakly associated with DR4. The IIB3 specificity is DQw1-related and is in linkage disequilibrium with DR2, DR4, DRw9 and DRw13. Thus, the DQw3-carrying haplotypes are either positive with TA10 or IIB3. The molecular and topological analysis has revealed that both TA10 and IIB3 determinants were expressed on a single DQ molecule that also carried the DQw3 determinants on DR5 and DR4 cell lines, respectively. Thus, a single DQ molecule generated multiple epitopes detected by alloantisera and/or MoAbs at least on the DQw3-carrying haplotypes. These would be useful for unraveling the largely unknown functions of the DQ class II molecules.

Antibodies, Monoclonal↗
PubMed1986

T cell receptor beta chain gene rearrangements in leukemias with immature T cell phenotype.

The arrangements of the T cell receptor (TCR) beta genes were studied in leukemias with immature T cell phenotype. Three cases of acute lymphocytic leukemia (ALL) and one case of chronic myelocytic leukemia in blastic crisis (CML-BC), which expressed only Tp40 antigen of cluster of differentiation (CD) 7 without erythrocyte rosette receptor (E), did not show rearrangements of TCR beta chain genes. Two of 5 ALL cases which expressed an additional T cell antigen, T1 of CD5, showed rearrangements of TCR beta genes. Two cases of CML-BC expressing T1 and Tp40, however, had unrearranged TCR beta genes. The results altogether showed that a part of E- T1+ Tp40+ ALL cases is of T cell origin.

Blast Crisis↗
PubMed1986

[Degradation of the insecticide parathion in soil].

Degradation of the insecticide Parathion in four types of soil from the Northeast of Brazil has been studied using radiometric techniques. In all the soil samples, sterilized or not, metabolites were detected with Rf values of 0.00 and 0.17 respectively--Silica Gel 60 F254 tlc plates (Merck); solvent system: hexane-acetone (4:1, v/v)--. However, 14CO2 was formed only with the non-sterilized soils and this was independent of the use or not of organic fertilizer. These results suggest that the two metabolites, mentioned above, are formed by a predominantly non-biological pathway, where as the formation of carbon dioxide requires the participation of the microbial flora of the soil. Analysis of the interaction of 14C-Parathion with soils shows that the extent of degradation of this insecticide is modified by adsorption on the soil particles.

Adsorption↗