Search PubMed⌕ Search

Biomedical subjects

T Osawa

Publications and source records attributed to T Osawa.

At least 163 records · Page 9Linked to original sources
PubMed1994

A unique amino acid sequence involved in the putative carbohydrate-binding domain of a legume lectin specific for sialylated carbohydrate chains: primary sequence determination of Maackia amurensis hemagglutinin (MAH).

The primary sequence of 247 amino acids of Maackia amurensis hemagglutinin (MAH) was determined using a protein sequencer. After digestion with endoproteinase Lys-C, Asp-N, Arg-C, or Glu-C of MAH, the resulting peptides were purified by reversed phase high performance liquid chromatography (HPLC) and then subjected to sequence analysis. The primary sequence of MAH was compared with those of several legume lectins, and it was found that the amino acid sequence of the putative carbohydrate-binding domain of MAH exhibited a high degree of homology with those of di-N-acetylchitobiose-binding Cytisus sessilifolius lectin I (CSA-I), Laburnum alpinum lectin I (LAA-I), and Ulex europaeus lectin II (UEA-II). In the legume lectins whose primary sequences have already been determined several amino acid residues involved in carbohydrate-binding were found to be conserved. Very interestingly, in the primary sequence of MAH, one amino acid residue corresponding to the conserved amino acid, asparagine, in the primary sequences of all other legume lectins was shown to be substituted by aspartic acid. This is the first report of the occurrence of an exceptional amino acid residue among the conserved amino acid residues in the carbohydrate-binding domain of the legume lectins.

Amino Acid Sequence↗
PubMed1994

Escherichia coli heat-labile enterotoxin binds to glycosylated proteins with lactose by amino carbonyl reaction.

The binding of Escherichia coli heat-labile enterotoxin (LT) type I to glycosylated proteins with lactose (Gal beta 1-4Glc) by amino carbonyl reaction was studied by the Western blot assay and by the microtiter well binding assay. LT bound to a lactose-alpha-lactalbumin amino carbonyl product (Lac-LA), whereas cholera toxin did not. The binding ability of Lac-LA was abolished by beta-galactosidase treatment, indicating that the terminal galactose is essential for the binding of LT. The binding of LT to Lac-LA was inhibited by galactose and lactose, and most effectively inhibited by lactulose (Gal beta 1-4Fru), which is a structural analog of the Amadori rearrangement product of the amino carbonyl reaction between lactose and an epsilon-amino group of a lysine residue (lactuloselysine). The results suggest that LT recognizes the portion of lactuloselysine in Lac-LA. LT also bound to a melibiose (Gal alpha 1-6Glc)-alpha-lactalbumin amino carbonyl product (Mel-LA), but the binding ability of Mel-LA was weaker than that of Lac-LA, suggesting that the beta 1-4 linked terminal galactose is dispensable but preferable for the binding. Furthermore, LT bound to the amino carbonyl products of lactose with beta-lactoglobulin, caseins, bovine serum albumin, and ovalbumin. These results indicate that LT binds to the amino carbonyl products between proteins and sugars containing the terminal galactose, such as lactose.

Animals↗
PubMed1994

Dual function of macrophage galactose/N-acetylgalactosamine-specific lectins: glycoprotein uptake and tumoricidal cellular recognition.

We investigated whether the interaction of peritoneal macrophages with extracellular ligands is mediated by C-type lectins specific for galactose and N-acetylgalactosamine. The carbohydrate-binding domain of mouse galactose/N-acetylgalactosamine-specific lectin was prepared in a recombinant form. The purified recombinant lectins were tested for competitive inhibition against glycoprotein uptake and against tumoricidal effect. Thioglycolate-elicited macrophages internalized galactosylated bovine serum albumin in vitro. The internalization was blocked by recombinant macrophage lectins. Activated macrophages obtained after intraperitoneal injection of a nonspecific immune potentiator, OK432, did not internalize galactosylated bovine serum albumin. These cells elicited a cytotoxic effect against P815 murine mastocytoma cells, and the effect was blocked by recombinant macrophage lectins. These results indicated that galactose/N-acetylgalactosamine-specific C-type lectins expressed on the surface of inflammatory macrophages and on activated tumoricidal macrophages mediate two distinct functions, i.e. glycoprotein uptake and tumoricidal effector mechanisms.

Acetylgalactosamine↗
PubMed1994

Decreased proliferation of pituitary cells of streptozotocin-induced diabetic rats in response to estradiol-17-beta.

Insulin is involved in the proliferation of fibroblasts, hepatocytes and certain other lines of cultured cells. In the present study an attempt was made to clarify the role of insulin in the proliferation of rat pituitary cells. Adult male rats of the Wistar/Tw strain were given intraperitoneal injections of streptozotocin (STZ) at a dose of 32.5 mg/kg. STZ-treated rats developed high blood glucose levels and low serum insulin levels. Proliferation of cells was examined by monitoring the cell uptake of bromodeoxyuridine (BrdU). Estradiol-17 beta (50 micrograms) was given to stimulate the proliferation of pituitary cells. The number of BrdU-containing cells was lower in STZ-treated rats than in controls. The responsiveness to estrogen in terms of cell proliferation was lower in STZ-treated rats than in controls. Treatment of STZ-treated rats with insulin increased the number of BrdU-containing cells and restored the responsiveness to estrogen. Insulin stimulated the proliferation of prolactin-secreting cells and growth hormone-secreting cells in estrogen-treated rats. These results suggest that insulin is necessary for the proliferation of pituitary cells.

Animals↗
PubMed1994

Enterotoxin-binding glycoproteins in a proteose-peptone fraction of heated bovine milk.

The binding of Escherichia coli heat-labile enterotoxin to caseins, whey proteins, milk fat globule membrane, and proteose-peptone fraction from bovine milk was studied by using the Western blot technique. Two toxin-binding glycoproteins, pp16k and pp20k, with molecular weights of 15,500 and 20,000, respectively, were detected only in a proteose-peptone fraction. These glycoproteins were partially purified by ammonium sulfate precipitation and Toyopearl HW 55 gel filtration chromatography. The binding ability to the toxin was destroyed by periodate treatment or beta-galactosidase treatment, indicating that a carbohydrate moiety, particularly a terminal galactosyl residue, was essential for the binding of the toxin. In contrast, the binding ability was not changed by mild acid treatment, and these glycoproteins did not bind cholera toxin, which can bind to ganglioside GM1, suggesting that the carbohydrate structure of the glycoproteins is different from that of GM1. The N-terminal amino acid sequence and immunoblot analysis indicated that the protein moieties of pp16k and pp20k are identical to alpha-lactalbumin and beta-lactoglobulin, respectively. These toxin-binding glycoproteins were not detected in whey proteins isolated from unheated skim milk, suggesting that they are newly generated during heat treatment of skim milk before the preparation of a proteose-peptone fraction.

Amino Acid Sequence↗
PubMed1994

[An enzyme-linked immunosorbent assay for the detection of IgG antibodies against urease of Helicobacter pylori].

We have developed an enzyme-linked immunosorbent assay (ELISA) for the detection of IgG antibodies against Helicobacter pylori (HP) using purified HP urease as an antigen. The urease was purified from ultrasonicated extract of HP by NaCl linear gradient system on DEAE-Sepharose 4B chromatography. Two molecular weight bands, 65kD and 27kD were observed on a SDS-PAGE gel in the purified urease sample. The urease antigen did not crossreact to rabbit antibodies prepared against Campylobacter coli and Campylobacter jejuni. Out of 93 gastric biopsy patients, sixty nine patients (74.2%) were positive in HP culture test. Serum HP antibody titers (AU: arbitrary unit) of HP culture positive and negative patients were 42.9 +/- 47.4 and 16.7 +/- 25.7 (mean +/- SD), respectively (p < 0.05). The ELISA system have sensitivity of 72.5% and specificity of 70.8%. We believe that the ELISA system is useful for diagnosis and monitoring of HP infection.

Adolescent↗
PubMed1994

[The optimal period for orally administered fluoropyrimidines as an adjuvant chemotherapy for gastric cancer--a pilot study using 5-FU tablets compared with surgical operation alone].

Long-term oral administration of fluoropyrimidines such as 5-fluorouracil (5-FU) or tegafur is commonly used as an adjuvant chemotherapy for gastric cancer, but the optimal period or optimal total doses of fluoropyrimidines have not been studied. Two hundred cases of macroscopical Stage II and III curatively resected gastric cancer patients were entered in this study, and divided into three groups (6 months group: mitomycin C was given i.v. at day 0 and day 1 and 5-FU tablets were orally administered at a dose of 200 mg/day for 6 months. 12 months group: MMC was given the same as for the 6 months group and 5-FU tablets were administered for 12 months. Surgery alone group: No chemotherapy, operation only). As the result, 185 cases were eligible. There was no significant difference between the 6 months group and the 12 months group among Stage II patients. Although there was also no significant difference between the 2 groups in Stage III patients, the survival curve of 12 months group was always higher than in the 6 months group. When comparing with surgery alone group, 5-year survival of the 12 months group was always higher than in the surgery alone group of Stage III patients; however, the survival rate in the 6 months group was worse than in the surgery alone group at Stage II and III. These results suggest that MMC i.v. and 12 months or over administration of 5-FU tablets is useful for Stage III gastric cancer patients, and that cooperative study is required comparing with surgery alone in Stage II patients.

Administration, Oral↗
PubMed1994

[Two cases of tuberculous constrictive pericarditis].

Case 1 was a 79-year-old male suspected of tuberculous constrictive pericarditis. He was admitted to our hospital because of surgical treatment. His heart failure was NYHA IV. Culture of pleural effusion and pericardial effusion was negative. But ADA level in pericardial effusion was found to be increased. So tuberculosis was suspected. Cardiac catheterization date was compatible with constrictive pericarditis. Case 2 was a 73-year-old female. She was admitted because of heart failure (NYHA IV). As RVP wave indicated dip & platou at cardiac catheterization, she was diagnosed as constrictive pericarditis. ADA level in pleural effusion increased. So tuberculosis was suspected as etiology of constrictive pericarditis. In both cases, after pericardiectomy, heart failure improved to NYHA I. Results of pathological examination were tuberculous inflammation.

Aged↗
PubMed1993

Purification and characterization of UDP-GlcNAc:Gal beta 1-4Glc(NAc) beta-1,3-N-acetylglucosaminyltransferase (poly-N-acetyllactosamine extension enzyme) from calf serum.

UDP-GlcNAc:Gal beta 1-4Glc(NAc) beta-1,3-N-acetylglucosaminyltransferase is involved in the initiation and the extension of poly-N-acetyllactosamine biosynthesis. This enzyme has been purified to about 125,000-fold with a 0.2% yield from calf serum. The purification was achieved by ammonium sulfate precipitation and chromatography on concanavalin A-Sepharose, DEAE-Toyopearl, SP-Toyopearl, Sephacryl S-200, AF-Blue-Toyopearl, and Mono Q columns. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed a single band corresponding to an apparent M(r) of 70,000. This component was specifically photoaffinity-labeled with 4-thiouridine diphosphate. Exoglycosidase digestion and methylation analysis of the reaction products demonstrated that the enzyme catalyzed the transfer of one N-acetylglucosamine to position C-3 of the terminal galactosyl residue of lactose or N-acetyllactosamine in the beta linkage. The enzyme required Mn2+ ions for its activity and showed a broad pH optimum around 7.0. Apparent Km values for lactose, N-acetyllactosamine, and UDP-GlcNAc were 18.2, 19.6, and 0.129 mM, respectively. Acceptor specificity was tested using several oligosaccharides. The results indicated that terminal Gal beta 1-4Glc(NAc) sequences (type II chains) were preferred substrates for the enzyme. Terminal Gal beta 1-3GlcNAc sequences (type I chains), Lewis X trisaccharides (Gal beta 1-4(Fuc alpha 1-3)GlcNAc), and monosaccharides (galactose) did not serve as substrates.

Animals↗
PubMed1993

Suppression of active oxygen-induced cytotoxicity by flavonoids.

The flavonoids quercetin, kaempferol, catechin and taxifolin suppressed cytotoxicity of active oxygen species (O2- and H2O2) on Chinese hamster V79 cells. Cytotoxicity of active oxygen species was assessed with a colony formation assay. The flavonoids prevented the decrease in the number of colonies caused by H2O2 or O2- at concentrations which were not themselves cytotoxic. There was a very substantial difference in the dose-dependency of the protective effects brought about by quercetin and kaempferol in contrast to catechin and taxifolin. The structure-activity relationship revealed that either the o-dihydroxy structure in the B ring or certain structures in the A and C rings of the flavonoids are necessary for the protective activities.

Animals↗
PubMed1993

Prognostic significance of histological type in gastric carcinoma with invasion confined to the stomach wall.

Survival was determined after resection for the two main histological types of gastric carcinoma, intestinal (n = 223) and diffuse (n = 170), in 393 patients with pT1 or pT2 tumours. Lymph node metastases were present in 94 patients. The 10-year survival rate was significantly lower for patients with intestinal-type than for those with diffuse-type carcinoma (72 versus 91 per cent, P < 0.005). In patients without nodal involvement, the 10-year survival rate was still lower for those with intestinal-type cancer (70 versus 94 per cent, P < 0.01). Recurrence of carcinoma was more often by haematogenous dissemination in patients with intestinal-type cancer. Although the results of resection for pT1 or pT2 gastric carcinoma can be acceptable, the introduction of adjuvant therapy based on histological findings may be necessary for patients with the intestinal type of cancer to prevent haematogenous spread of carcinoma to the liver.

Adenocarcinoma↗
PubMed1993

Chromium and tritiated thymidine releases from target cells are differential events in human monocyte/macrophage-mediated cytotoxicity.

Cytotoxic properties of human activated macrophages were investigated by measuring both 51Cr and [3H]TdR releases from prelabeled target cells. The kinetic study of macrophage-mediated cytotoxicity indicated that 51Cr and [3H]TdR releases showed a distinct time course. Next, when [3H]TdR release was measured as a parameter for cytotoxicity, pretreatment of activated macrophages with either actinomycin D or emetine remarkably decreased their cytotoxicity in a dose-dependent manner. In contrast, the pretreatment with these inhibitors had little effect on 51Cr release. Furthermore, the addition of Zn2+ in the assay medium caused the decrease in [3H]TdR release but not 51Cr release from the target cells. Taken together, our findings indicate that 51Cr and [3H]TdR releases from the target cells are induced by activated macrophages through different cytotoxic mechanisms; the former does not require RNA and protein syntheses in macrophages during coculture, whereas the latter requires them. Our findings also suggest that macrophage-derived nuclease may play an important role for inducing [3H]TdR release from the target cells.

Chromium Radioisotopes↗
PubMed1993

Antimutagenic effects of N-methyl-valyl-amiclenomycin (BA-2) isolated from the metabolites of Streptomyces sp.

A novel antimutagenic factor, BA-2, active against UV-induced mutagenesis in Escherichia coli WP2 was isolated from the metabolites of Streptomyces sp. strain AJ9455. BA-2 also suppressed mutations induced by 4-nitroquinoline N-oxide (4-NQO) and furylfuramide (AF-2) in E. coli WP2s (uvrA) without any decrease of cellular viability. BA-2 strongly inhibited the UV induction of SOS repair functions when it was monitored by beta-galactosidase activity expressed from the sulA::lacZ fusion gene of strain PQ37. It is assumed that the antimutagenic effect of BA-2 on mutagenesis induced by UV, 4-NQO or AF-2 was the result of inhibition of induction of the inducible error-prone SOS repair. The structure of BA-2 was considered to be N-methyl-valyl-amiclenomycin, and the structural unit of 4-amino-2,5-cyclohexadiene must be essential for the antimutagenic activity, since deamination by heating results in the loss of antimutagenic activity of BA-2.

Aminobutyrates↗
PubMed1993

The protective role of gallic acid esters in bacterial cytotoxicity and SOS responses induced by hydrogen peroxide.

The effects of gallic acid and its esters on H2O2-induced cytotoxicity, mutagenicity and SOS response were investigated in bacterial assay systems, i.e., the Ames test with Salmonella typhimurium TA104 and the SOS chromotest with E. coli PQ37. In the Ames test, gallic acid esters showed protective effects against H2O2-induced cytotoxicity and no effects on the number of revertant colonies. In the SOS chromotest, gallic acid esters lowered the SOS induction factor raised by H2O2. Throughout the study, the effects of gallic acid itself were weak or negligible, and lauryl gallate was most effective among the three gallic acid esters. This structure-activity relationship indicates the similarity of the protective effects of gallic acid esters on the H2O2-induced damages to both bacterial and mammalian cells.

Escherichia coli↗
PubMed1993

Two cytosolic puromycin-sensitive aminopeptidase isozymes in chicken brain: molecular homology to brain-specific 14-3-3 protein.

Two puromycin-sensitive aminopeptidase isozymes (PSA-I and PSA-II) were isolated from chicken brain cytosol by ammonium sulfate fractionation followed by column chromatography on Cellex D and AH-Sepharose 4B and separated on Bio-Gel HTP. Each was purified to homogeneity on Sephadex G-200, Arg-Tyr-AH-Sepharose, Bio-Gel HTP, and preparative gel electrophoresis. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis, PSA-I appeared to be a monomer with a molecular mass of 105 kDa, and PSA-II to be composed of two subunits of 25 kDa and 100 kDa. The tryptic maps of 100 kDa and 105 kDa protein in HPLC are different in peak frequency, height, and composition. The internal peptide sequence of PSA-I has a considerable homology to PSA-II. Both isozymes have repeated copies of common peptide segments and have no significant sequence homology to other peptidases and proteinases. These thio and Co(2+)-activated isozymes have a neutral pH optimum and are inhibited by puromycin and bestatin. PSA-II is more sensitive to trypsin and heat treatment, has a lower Km to Met-enkephalin, and is more active on Arg BNA and Pro BNA. Our results suggest that PSA-I and PSA-II derive from translation of two RNAs of a new gene family related to the brain-specific 14-3-3 protein.

14-3-3 Proteins↗
PubMed1993

Characterization of the 50 kDa protein phosphorylated in concanavalin A-stimulated mouse T cells.

Concanavalin A (Con A) stimulated the phosphorylation of a protein with a molecular mass of 50 kDa and an approximate pI of 4.7 (p50) in mouse spleen T cells. The phosphorylation of p50 was also stimulated by a protein kinase C activator, phorbol myristate acetate (PMA), but not by a calcium ionophore, A23187. This phosphorylation of p50 was limited to serine and threonine residues in both Con A- and PMA-stimulated T cells. Purification and protein sequence analysis of p50 enabled us to identify it as a lymphocyte-specific putative Ca(2+)-binding protein (LSP-1). These results suggest that p50 may have some function, which is regulated through serine/threonine phosphorylation and the intracellular Ca2+ concentration, downstream of the phosphoinositide signaling system in the T cell activation cascade.

Amino Acid Sequence↗
PubMed1993

Identification of human T cell hybridoma-derived macrophage activating factor as interleukin-2.

Macrophages are activated by a two-step mechanism involving at least two kinds of factors, a priming and a triggering factor, to become cytotoxic to various tumor cells. In the present study, we purified macrophage-activating factor for cytotoxicity I (MAF-C I), defined as a priming macrophage activating factor (MAF), by about 1,600-fold from the culture supernatant of a human T cell hybridoma, H3-E9-6, by a series of chromatographic procedures. We identified MAF-C I activity released from H3-E9-6 cells as interleukin-2 (IL-2) from the following findings. (i) The physicochemical properties of MAF-C I and IL-2 were almost identical. (ii) Purified MAF-C I active fraction also showed T cell proliferating activity. (iii) MAF-C I activity in the purified fraction was completely neutralized by anti-IL-2 antibodies. (iv) Human recombinant IL-2 (rIL-2), at a suboptimal dose, and lipopolysaccharide (LPS) synergistically induced monocyte-mediated cytotoxicity.

Cytotoxicity, Immunologic↗