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M Ohta

Publications and source records attributed to M Ohta.

At least 811 records · Page 45Linked to original sources
PubMed1990

Complete primary structure of the human estrogen-responsive gene (pS2) product.

pS2 is a human gene whose transcription is directly triggered by estrogen in human breast cancer cells (MCF-7). We described here the complete primary structure of the pS2 gene product. The pS2 protein purified from conditioned medium of MCF-7 cells was S-pyridylethylated and digested with TPCK-trypsin. Five major fragments were obtained by reverse-phase HPLC. Amino acid sequence analysis of these tryptic peptides established that the pS2 protein comprises a 60-amino acid polypeptide. The sequence of the pS2 protein was completely identical to that deduced from the nucleotide sequence of the pS2 gene, if the signal polypeptide is excluded. Furthermore, two cDNA clones encoding an 84-amino acid precursor pS2 protein were isolated from a cDNA library which was constructed with RNA from MCF-7 cells cultured in the presence of estrogen. The nucleotide sequence of one clone (pS2B1) was identical to that of pS2 cDNA previously reported except for one nucleotide in the 3' untranslated region. The other clone (pS2B2) was longer by 73 nucleotides, at the 5' end, than pS2B1. The additional 73 nucleotides are located just upstream of the sequence of pS2B1 in the structure of the pS2 gene, indicating that the pS2 gene has two start sites for transcription. However, a mRNA molecule corresponding to pS2B1 but not to pS2B2 was detected in the cells on RNA blot hybridization analysis, indicating that one transcriptional start site is mainly used.

Amino Acid Sequence↗
PubMed1990

Structure of an allergenic pentasaccharitol, Gp-1 beta-b6, isolated from a sea squirt antigen, Gi-rep, as a minimum structural unit responsible for its allergenicity.

An allergenic pentasaccharitol, Gp-1 beta-b6, was isolated as a minimum structural unit responsible for the allergic reaction in skin of patients with sea squirt allergy from a saccharitol fraction, Gp-1 beta-b, that had been liberated by beta-elimination from a glycopeptide in a Pronase digest of a sea squirt antigen, Gi-rep. Methylation/GC-MS and FAB-MS analyses indicated the sugar sequence of Gp-1 beta-b6 to be GalNAcl----2Fucl----(GalNAc1----) 3,4GlcNAc1----3GalNAc-ol. To analyze the structure in more detail, Gp-1 beta-b6 was labeled with p-aminobenzoic acid ethyl ester (ABEE), i.e., the reducing terminal 3-O-substituted GalNAc-ol of the saccharitol was oxidized to 2-O-substituted L-ThrNAc with equimolar periodate, and the resultant aldehyde was labeled with ABEE by reductive amination. The ABEE-labeled Gp-1 beta-b6 was subjected to sequential exoglycosidase digestion with beta-N-acetylhexosaminidase, alpha-N-acetylgalactosaminidase, and alpha-fucosidase, and the digests were chromatographed on an HPLC column of TSK gel Amide 80. From the results of the HPLC, methylation/GC-MS, and FAB-MS analyses of the digests of the labeled substrate, the structure of Gp-1 beta-b6 was determined to be GalNAc alpha 1----2Fuc alpha 1----3(GalNAc beta 1----4)GlcNAc beta 1----3GalNAc-ol. Enzymatic elimination of either the non-reducing terminal beta-GalNAc or the non-reducing terminal alpha-GalNAc led to inactivation of the allergenic pentasaccharitol. Accordingly, it is possible that the allergenic saccharitol contains two disaccharide units as the allergy-specific epitopes, one GalNAc alpha 1----2Fuc alpha 1---- and the other GlcNAc beta 1----4GLcNAc beta 1----.

Allergens↗
PubMed1990

Positive results of combined therapy of surgery and intraperitoneal hyperthermic perfusion for far-advanced gastric cancer.

To evaluate the clinical efficacy of intraperitoneal hyperthermic perfusion (IPHP) for far-advanced gastric cancer, particularly with peritoneal seeding, we investigated the survival times of 59 patients who underwent distal subtotal gastrectomy, total gastrectomy, or total gastrectomy combined with concomitant resection of some of the remaining intra-abdominal organs. In all the 30 patients given IPHP, no cancer cells were present posthyperthermically in the lavage from the Douglas pouch. The 30 patients given IPHP lived longer than the 29 patients not given IPHP (p = 0.001), with a 1-year survival rate of 80.4% in the former group compared to 34.2% in the latter. With respect to a comparison of survival time of patients with peritoneal seeding, 7 patients not given IPHP had a 6-month survival rate of 57.1% and did not survive more than 9 months, whereas 20 patients given IPHP had 1- and 2-year survival rates of 78.7% and 45.0%, respectively; here the difference was significant (p = 0.001). The IPHP and control groups without peritoneal metastasis included 10 and 22 patients, respectively, and the 1-year survival rates are 85.4% and 45.3%, respectively. The survival rates of the former exceeded those of the latter, with p = 0.015 by the generalized Wilcoxon test. Thus this combined therapy offers the promise of extended survival for patients with far-advanced gastric cancer.

Combined Modality Therapy↗
PubMed1990

Relationship between Mg2(+)-induced hexagonal assembly of R-form lipopolysaccharides and chemical structure of their R-cores.

The relationship between formation of the Mg2(+)-induced hexagonal lattice structure by R-form lipopolysaccharides (LPS) and chemical structure of their R-cores was investigated using different kinds of R-form LPS from a series of mutants of Salmonella minnesota or S. typhimurium. The optimal experimental condition for formation of the hexagonal lattice structure was to suspend LPS preparations, from which cationic material was removed by electrodialysis, in 50 mM tris (hydroxymethyl) aminomethane buffer at pH 8.5 containing 10 mM MgCl2. Under this experimental condition, Rb1 LPS formed the hexagonal lattice structure with the lattice constant of 14.0 +/- 0.2 nm. Ra LPS, which possesses the full length of R-core, also formed the hexagonal lattice structure but its lattice constant was larger (18.1 +/- 0.2 nm) than that of Rb1 LPS (the lattice structure by Ra LPS was looser than that by Rb1 LPS). All the other R-form LPS preparations tested, RcP+, PcP-, Rd1P-, and Re LPS, whose R-cores are shorter than that of Rb1 LPS, did not form the hexagonal lattice structure, but formed membranous structures showing various shapes which consisted of multiple bilayer structures. Failure to form the hexagonal lattice structure was the common feature of these kinds of R-form LPS irrespective of temperature at which the LPS suspensions in 10 mM MgCl2-50 mM Tris buffer were incubated. From the results of the present study it was concluded that capability of R-form LPS to form the hexagonal lattice structure has a close correlation with the chemical structure of their R-cores.

Carbohydrate Sequence↗
PubMed1990

Inhibitory effect of Ca2+ on formation of Mg2(+)-mediated two-dimensional hexagonal lattice structure by an R-form lipopolysaccharide from Klebsiella pneumoniae.

When the R-form lipopolysaccharide (LPS) from Klebsiella pneumoniae strain LEN-111 (O3-:K1-), from which cationic material had been removed by electrodialysis, was suspended in 50 mM Tris buffer at pH 8.5 containing 0.1 mM or higher concentrations of MgCl2, it formed an ordered two-dimensional hexagonal lattice structure and its center-to-center distance (lattice constant) depended upon the concentration of MgCl2 and reached the shortest value (14 nm) at 10 mM. In contrast, in the presence of 0.1 to 10 mM CaCl2 in place of MgCl2, the electrodialyzed LPS did not form such an ordered hexagonal lattice structure but formed an irregular network structure with a center-to-center distance of 19 to 20 nm. We investigated interaction of Mg2+ and Ca2+ in formation of the hexagonal lattice structure by the electrodialyzed LPS suspended in 50 mM Tris buffer at pH 8.5. When 0.1 mM or higher concentrations of CaCl2 were mixed with 1 mM MgCl2 or when 1 mM or higher concentrations of CaCl2 was mixed with 10 mM MgCl2, the electrodialyzed LPS did not form the hexagonal lattice structure of the magnesium salt type but formed the irregular network structure of the calcium salt type. In the coexistence of equimolar or higher concentrations of CaCl2 together with 1 or 10 mM MgCl2, the binding of Mg to the electrodialyzed LPS was significantly inhibited and, conversely, the binding of Ca was enhanced as compared with when MgCl2 or CaCl2 was present alone. However, the coexistence of 10 times less molar concentrations of CaCl2 did not significantly inhibit the binding of Mg to the electrodialyzed LPS. Therefore, the inhibition of formation of the Mg2(+)-mediated hexagonal lattice structure of the electrodialyzed LPS by equimolar or higher concentrations of CaCl2 accompanied the inhibition of binding of Mg but that by 10 times less molar concentrations of CaCl2 did not accompany it.

Calcium↗
PubMed1990

Rapid small-scale preparation method of cell surface polysaccharides.

A rapid small-scale method of extraction of lipopolysaccharide (LPS) and capsular polysaccharides was developed for the purpose of identification of chemotypes of LPS and serotypes of capsular antigens. Cell surface polysaccharides were prepared within less than 2 hr from 1.5 ml of broth or suspension of colonies cultured overnight. The preparations were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis for LPS, and by double diffusion gel precipitation (Ouchterlony) test and blotting to nitrocellulose membrane for capsular polysaccharide. The analyses with the preparations obtained by the method could provide adequate results capable of identifying chemotypes of LPS and serotypes of capsular antigens.

Antigens, Bacterial↗
PubMed1990

Electron microscopic observation of crystals of Escherichia coli K-12 lipopolysaccharide.

Previously we showed that Salmonella minnesota Re and Ra lipopolysaccharides (LPSs) and Escherichia coli K-12 LPS formed three-dimensional crystals, either hexagonal plates or solid columns, when they were precipitated by the addition of 2 volumes of 95% ethanol containing 375 mM MgCl2 and incubated in 70% ethanol containing 250 mM MgCl2, and stored at 4 C for 10 days. Later, Escherichia coli K-12 LPS thus treated was found to form discoid crystals as well as hexagonal plate crystals and solid column crystals. Analysis by electron diffraction of the discoid crystals from the direction perpendicular to the basal plane showed that they consisted of hexagonal lattices with the a axis of 4.62 A. This result was quite the same as that of the hexagonal plate crystals. Electron micrographs of the edges of the discoid crystals revealed stacked sheets of the hexagonal plate crystals. From these results it was concluded that formation of the discoid crystals results from irregular overlapping of the hexagonal plate crystals.

Crystallization↗
PubMed1990

lck suppresses gene expression from various promoters including human T-cell leukemia virus type I promoter.

The T-lymphocyte-specific tyrosine kinase gene, lck, is expressed in T-lymphocyte cell lines, except for several human T-cell leukemia virus type I(HTLV-I)-transformed T-lymphocyte cell lines, which produce HTLV-I. By introducing an lck-expression vector, we found that lck product suppresses gene expression from HTLV-I promoter in a transient assay. Moreover, various other promoters of cellular genes or viruses were found to have their transcriptional activity repressed by lck.

Chloramphenicol O-Acetyltransferase↗
PubMed1990

Demonstration of lipid A-binding proteins on murine lymphoma cells using R-mutant gram-negative bacteria as a detector.

Some R-mutant Escherichia coli and Salmonella heavily adhered to murine lymphoma cells of B cell and T cell lineages. This adhesion was primarily mediated by membrane-localized proteins on tumor cells, which bind the polymyxin B-reactive hydrophilic structure of lipis A on bacteria. SDS-PAGE analysis of tumor cell membranes showed that proteins or glycoproteins of MW = around 45Kd, 25-35Kd and around 15Kd preferentially bind lipid A. Various lymphoma cell lines binding the bacteria at different levels possessed lipid A-binding proteins of slightly different compositions. We conclude that lymphoma cells carry not a single but a group of lipid A-binding proteins in their membranes.

Animals↗
PubMed1990

[Nosocomial infection by new quinolone resistant Enterobacter cloacae].

For the past two years, five strains of new quinolone resistant Enterobacter cloacae have been isolated from three patients in our hospital; strain A was isolated from patient A, strain B from patient B, and strains C1, C2, C3 from patient C. These five strains were resistant to new quinolones and other antimicrobial agents including ampicillin, piperacillin, methicillin, cefotaxime, cefoperazone, kanamycin, gentamicin, tetracycline, minocycline, and chloramphenicol. Plasmid DNA profiles on agarose gel indicated that strain B and C3 carried completely the same plasmid pattern, but strain A gave a different plasmid pattern. Furthermore chromosomal DNAs extracted from strains A, B and C3 were digested with restriction endonucleases EcoR I, BamH I and Sma I. They were separated by pulsefield gel electrophoresis. The banding profiles of strains B and C3 showed the same pattern. It is, therefore, highly suggested that strains B and C3 are the same E. cloacae strain, although isolated from different patients at different time. The possible route of nosocomial infection between these two patients who were hospitalized in the same room after an interval of 4 months was discussed.

4-Quinolones↗
PubMed1990

Recombinant granulocyte colony-stimulating factor and lipopolysaccharide maintain the phenotype of and superoxide anion generation by neutrophils.

Superoxide anion (O2-) generation by human blood neutrophils induced by phorbol myristate acetate, formyl-methionyl-leucyl-phenylalanine, and monoclonal antibody YI51 was measured 24 h after incubation in medium alone, medium with recombinant human granulocyte colony-stimulating factor (rG-CSF), and medium with lipopolysaccharide (LPS). Monoclonal antibody YI51 was able to bind to neutrophils and induce O2- generation after the addition of anti-mouse immunoglobulin antibody as a cross-linking agent. In the 24-h culture, there was no significant difference in neutrophil survival among the three cultures. The amount of O2- generated by neutrophils in control medium markedly decreased compared with that before culture. However, cells in medium with rG-CSF or LPS maintained the ability to generate O2- well or moderately, respectively. Thus, the activity maintained by rG-CSF and LPS was neutralized by the anti-G-CSF serum. Furthermore, significant amounts of G-CSF were detected in supernatants of neutrophils cultured with LPS for 24 h. It was not detectable, however, in control supernatants. To examine whether the phenotype of the plasma membrane of cells changed in the 24-h culture, expression of CD16 (FcR III) and YI51 antigens was analyzed by flow cytometry. The expression of CD16 and YI51 antigens on cells cultured with rG-CSF or LPS was maintained compared with that of control cells. These observations thus indicate that G-CSF is one of the factors essential to maintain the functioning and phenotype of mature neutrophils.

Antigens, CD↗
PubMed1990

Detection of lipopolysaccharides by ethidium bromide staining after sodium dodecyl sulfate-polyacrylamide gel electrophoresis.

A rapid and easy method for staining lipopolysaccharides with ethidium bromide is described. Lipopolysaccharides could be visualized by ethidium bromide with almost the same sensitivity as found with the silver-staining method in less than 30 min. The ethidium bromide-staining method was particularly suitable for staining lipopolysaccharides possessing acidic O-specific polysaccharides, which were poorly visualized by silver staining.

Electrophoresis, Polyacrylamide Gel↗
PubMed1990

Crystallization of R-form lipopolysaccharides from Salmonella minnesota and Escherichia coli.

Salmonella minnesota Re and Ra lipopolysaccharides (LPSs) and Escherichia coli K-12 LPS formed three-dimensional crystals, either hexagonal plates (preferential growth along the a axis) or solid columns (preferential growth along the c axis), when they were precipitated by the addition of 2 volumes of 95% ethanol containing 375 mM MgCl2 and incubated in 70% ethanol containing 250 mM MgCl2 at 4 degrees C for 10 days. Analyses of crystals suggested that they consist of hexagonal lattices with the a axis (a side of the lozenge as a unit cell on the basal plane) of 0.462 nm for all these three kinds of LPSs and the c axes (perpendicular to the basal plane) of 5.85, 8.47, and 8.75 nm for S. minnesota Re and Ra LPSs and E. coli K-12 LPS, respectively, and that hydrocarbon chains of the lipid A portion play the leading part in crystallization, whereas the hydrophilic part of the lipid A (the disaccharide backbone) and R core exhibit a disordered structure or are in a random orientation. The phenomenon of doubling of the a axis to 0.924 nm was observed with crystals of S. minnesota Re LPS when they were incubated in 70% ethanol for an additional 180 days, but not with crystals of S. minnesota Ra LPS or E. coli K-12 LPS. S. minnesota S-form LPS possessing the O-antigen-specific polysaccharide and S. minnesota free lipid A obtained by acid hydrolysis of Re LPS did not crystallize under the same experimental conditions.

Carbohydrate Conformation↗
PubMed1990

Molecular characterization of an Enterobacter cloacae gene (romA) which pleiotropically inhibits the expression of Escherichia coli outer membrane proteins.

The introduction of a newly cloned Enterobacter cloacae chromosomal gene romA, into Escherichia coli and E. cloacae resulted in enhancement of resistance to quinolones, beta-lactams, chloramphenicol, and tetracycline. The primary effect of romA on a multicopy vector in E. coli was almost complete inhibition of OmpF expression in the outer membrane. From the experiments with ompR and envZ mutants or with ompF-lacZ and ompC-lacZ fusion plasmids, it was concluded that this inhibition is posttranscriptional. The introduction of romA on a multicopy vector into strains with micF deletion elicited only a moderate decrease in OmpF protein expression. This indicates that reduction of OmpF expression by romA is partly mediated posttranscriptionally by the activation of micF. Moreover, the overexpression of RomA protein from an isopropyl-beta-D-thiogalactopyranoside (IPTG)-inducible promoter resulted in nearly complete inhibition of expression of OmpC and OmpA, as well as OmpF. Taken together with an observation in a recent study that overexpressed OmpC inhibited the synthesis of OmpA and LamB, a possible inhibitory mechanism at the translational stage of the synthesis of outer membrane proteins should also be considered. By Southern hybridization, romA was generally detected in the chromosomes of all E. cloacae strains tested but not in the E. coli K-12 chromosome. Sequence data show that there is an open reading frame specifying 368 amino acids residues including a putative signal peptide. RomA appears to belong to the outer membrane protein family since it was extractable from an outer membrane preparation, but no sequence homology to other outer membrane proteins was detected.

Amino Acid Sequence↗
PubMed1990

Plasma active and inactive renin concentrations in children.

Plasma active and inactive renin concentrations (PARC and PIRC) were measured by immunoradiometric assay. Age-related changes in PARC, PIRC and the ratio of PARC/PIRC were studied in 78 normal children, age 1 month to 15 years. The effects of upright position for 15 min were also investigated in 7 postmenarcheal girls. PARC and PIRC in infants were significantly higher than in older children and their ratio of PARC/PIRC was significantly lower than in prepubertal children. During puberty, PARC, PIRC and their ratio were higher in premenarcheal girls than in postmenarcheal girls. In the upright position, PARC, PIRC and the ratio were increased significantly. These finding suggest that: (1) the production of inactive renin is increased but the activation of renin may be lowered in infants; (2) the activation of renin is affected by the menstrual cycle, and (3) the production and activation of renin are increased during short term standing.

Adolescent↗
PubMed1990

Antibodies to synthetic peptide (125-148) of the alpha-subunit of human nicotinic acetylcholine receptor in sera from patients with myasthenia gravis.

We measured the amount of antibodies to a synthetic peptide that corresponds to the alpha-subunit residues Lys125-Thr148 of human acetylcholine receptor (AChR) in myasthenic sera. We detected anti-peptide antibodies in 52% (89/171) of the patients with myasthenia gravis (MG), but none in any of the healthy controls. Anti-peptide antibodies should provide a valuable immunologic parameter for the clinical evaluation of MG, but no apparent correlation was observed between the titers of anti-peptide and anti-AChR antibodies.

Autoantibodies↗
PubMed1990

Characterization of aldose reductase and aldehyde reductase from the medulla of rat kidney.

Aldose reductase and aldehyde reductase from the medulla of the rat kidney have been purified to homogeneity by using affinity chromatography, gel filtration and chromatofocusing. The molecular weights of aldose reductase and aldehyde reductase by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis were found to be 37000 and 39000, respectively. The isoelectric points of aldose reductase and aldehyde reductase were found to be 5.4 and 6.2 by chromatofocusing, respectively. The major differences of amino acid compositions between both enzymes were found in serine, alanine and aspartic acid. Substrate specificity studies showed that aldose reductase utilized aldo-sugars such as D-glucose and D-galactose, but aldehyde reductase did not use them. The Km values of aldose reductase for various substrates were lower than those of aldehyde reductase. Aldose reductase utilized both reduced nicotinamide adenine dinucleotide phosphate (NADPH) and reduced nicotinamide adenine dinucleotide (NADH) as coenzymes, whereas aldehyde reductase utilized only NADPH. The presence of the sulfate ion resulted in a dramatic activation of aldose reductase whereas it did not affect aldehyde reductase activity. These enzymes were strongly inhibited by the known aldose reductase inhibitors. However, aldose reductase was more susceptible than aldehyde reductase to inhibition by the aldose reductase inhibitors.

Aldehyde Oxidoreductases↗