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S Ohkuma

Publications and source records attributed to S Ohkuma.

At least 109 records · Page 6Linked to original sources
PubMed1993

[Separation of glycoproteins from cyst fluids of human ovarian cystomas in benign and their some chemical and serological properties].

Perchloric acid-soluble fractions (PASFs 1-3) which were obtained from cyst fluids of two patients [(Nos. 1 (blood group B) and 2 (blood group A))] with ovarian mucinous cystadenoma and one patient (No. 3 (blood group A)) with ovarian dermoid cyst in benign, were identified as glycoproteins by their chemical composition analyses, respectively. Reactivities of PASFs 1-3 against blood group anti-sera and lectins suggest that these PASFs did not contain MN blood group substances, Vgu glycoproteins and T-active glycoproteins. PASF 1 was separated into 11 fractions by Sephacryl S-500 gel filtration. From chemical composition, SDS-PAGE and serological property of the main fraction (Fr. 5), other one fraction (Fr. 7) and mild acid hydrolysates of these two fractions, it is possible to presume that PASF 1 consisted of a large number of AB-active and fucose-rich glycoproteins with high molecular weights and some of these glycoproteins bear either NeuNAc alpha 2-->6GalNAc (sialyl Tn) group or both sialyl Tn and sialylated T groups.

Adult↗
PubMed1993

[Vicia graminea lectin or Vicia unijuga lectin-binding (Vgu) glycoproteins as new tumor-associated substances].

The purification and serological and chemical properties of Vicia graminea lectin (VGA) and Vicia unijuga lectin (VUA) were described, and then the binding-specificity of anti-M and -N antibodies and both the lectins was discussed in this review. On the basis of the facts that Vgu glycoproteins which react with either VGA or VUA but not with anti-M and -N antibodies and were not detected in human normal organ tissues and sera, were separated and identified as mucin-type glycoproteins with very high molecular weights from human cancerous organ tissues, ascitic fluids of cancer patients and cyst fluids of human ovarian cystadenoma in malignant, it was concluded that Vgu glycoproteins are new tumor-associated substances.

Autoradiography↗
PubMed1993

[Serological property of perchloric acid-soluble glycoprotein fractions of human meconium].

Perchloric acid-soluble fractions (PASFs) were separated, in yields of 87.0-151.9 mg per 1.0 g of wet meconium sample, from six samples of human meconium, and identified as glycoproteins having 41.2-74.1% carbohydrate by chemical composition analysis. Six PASFs reacted with anti-A, -B, -Lea and -Leb sera, but did not react with anti-M and -N sera. These PASFs alos reacted with many lectins such as DBA, UEA-I, Vicia graminea lectin (VGA), Vicia unijuga lectin (VUA), Con A, WGA, RCA-I, PHA-E, SBA, SJA, and influenza A and B viruses. The serological results show that six PASFs contained VGA or VUA-binding (Vgu) glycoproteins as new oncofetal substances, but did not contain M and N blood group substances.

Amino Acids↗
PubMed1993

Functional alterations in GABAA receptor complex induced by ethanol.

Possible direct actions of ethanol on cerebral GABAA receptor complex have been analyzed using purified GABAA receptor complex from the bovine cerebral cortex and its reconstituted vesicles. Addition of ethanol to the reconstituted vesicles with purified GABAA receptor complex induced a significant increase of GABA-dependent 36Cl- influx. Furthermore, the reconstituted GABAA receptor pretreated with 20 mM ethanol, which had no effect on GABAA receptor binding, also showed an increase of the GABA-dependent 36Cl- influx. On the other hand, the GABA-dependent 36Cl- influx into membrane vesicles prepared from alcohol dependent mouse brain showed a significant decrease, although this decrease was found to be recovered at 8 hours after the withdrawal of ethanol inhalation. Moreover, the expression of mRNA for GABAA receptor alpha 1-subunit in the brain showed an elevation in alcohol dependent condition, although this elevation was recovered to the control level after the withdrawal of alcohol inhalation. The present results suggest that continuous inhalation of ethanol in vivo may induce not only the alterations in the function of GABAA receptor complex but also that in the expression of mRNA for the receptor in the brain.

Alcoholism↗
PubMed1992

Isolation and characterization of a Vicia graminea and Vicia unijuga lectins-binding (Vgu) glycoprotein with Thomsen-Friedenreich (T) activity from human liver metastases of pancreas carcinoma.

1. Perchloric acid-soluble fraction from liver metastases of pancreas carcinoma of a patient with blood group B, was subjected to a systematic affinity chromatography using Vicia unijuga lectin (VUA) and Arachis hypogaea anti-T lectin (PNA) as immobilized ligands and separated into three fractions, B-active glycoprotein fraction, serologically inactive glycoprotein fraction and glycoprotein (VP) fraction exhibiting reactivities for Vicia graminea lectin (VGA), VUA and PNA. 2. VGA- and VUA-binding (Vgu) glycoprotein with Thomsen-Friedenreich (T) activity which was isolated, in a high state of purity, from VP fraction by HPLC using Asahipak GS-710 column, was demonstrated to be a mannose-rich glycoprotein with mol. wt of 1492 kDa and contained 40.40% carbohydrate.

Antigens, Tumor-Associated, Carbohydrate↗
PubMed1992

Presence of a Vicia unijuga lectin-binding (Vgu) glycoprotein with Thomsen-Friedenreich (T) activity and Vgu glycoproteins in human primary hepatocellular carcinoma.

1. Twenty perchloric acid-soluble glycoprotein fractions (PASFs) were separated from carcinomatous and non-carcinomatous regions of the livers of 5 patients with primary hepatocellular carcinoma (HCC) and 5 patients with a complication of HCC and hepatocirrhosis (HC). 2. In autoradiography using 125I-labelled Vicia unijuga lectin (VUA) and 125I-labelled Arachis hypogaea anti-T lectin as probes, 10 PASFs from carcinomatous regions of the livers of 10 patients gave 1 Vgu glycoprotein with T activity and/or 1-4 Vgu glycoproteins, respectively, and among 10 PASFs from non-carcinomatous regions of the livers of 10 patients, 7 PASFs gave no glycoproteins, respectively. 3. These results show that a Vgu glycoprotein with T activity and Vgu glycoproteins occur in HCC and in a complication of HCC and HC as oncofetal antigens.

Antibodies↗
PubMed1992

Muscimol-induced reduction of GABAA receptor alpha 1-subunit mRNA in primary cultured cerebral cortical neurons.

The expression of mRNA for GABAA receptor alpha 1-subunit in mouse cerebral cortical neurons in primary culture was examined using RNA blot analysis and ribonuclease protection assay following the treatment of neurons with muscimol, a selective agonist of GABAA receptor. The level of mRNA for GABAA receptor alpha 1-subunit showed a decrease in comparison with that in non-treated cells, whereas no changes in the level of beta-actin mRNA were noted under the same experimental conditions. This muscimol-induced reduction in GABAA receptor alpha 1-subunit mRNA was counteracted by the simultaneous exposure of neurons to both bicuculline, an antagonist of GABAA receptor, and muscimol. The expression of mRNA for GABAA receptor alpha 1-subunit also showed a decline by the treatment of cells with flunitrazepam alone, an agonist of benzodiazepine receptor, and this change was also abolished by the simultaneous exposure of cells to flunitrazepam and Ro15-1788, an antagonist for central benzodiazepine receptor. These results suggest that the continuous stimulation of cerebral GABAA receptor complex may induce the reduced expression of mRNA for the receptor complex.

Animals↗
PubMed1992

Association of functional alteration in intracellular signal transduction systems with the occurrence of up-regulation of muscarinic receptors in primary cultured neurons.

1. Alterations in intracellular biosignaling systems associated with the up-regulated muscarinic receptor were investigated using primary cultured neurons exposured to 10 nM atropine for 5 days. 2. In neurons treated with atropine, the response of PI turnover to muscarinic stimulation decreased in comparison with that in non-treated neurons. 3. The GTP gamma S-stimulated PI turnover also reduced in neurons possessing up-regulated muscarinic receptor, although phospholipase C activity was not different in these two types of neurons. 4. In addition, the long-term exposure (5 days) to atropine induced the increase in GTPase activity and [3H]GppNHp binding. 5. These results suggest that the decreased response of PI turnover to muscarinic stimulation may be attributed to the functional deterioration of G-protein itself and/or coupling between G-protein and phospholipase C. 6. The present results also strongly suggest that the accentuation of the function of G protein may occur in association with the up-regulation of muscarinic receptor.

Animals↗
PubMed1992

Molecular cloning of a rat liver cDNA encoding the 16 kDa subunit of vacuolar H(+)-ATPases: organellar and tissue distribution of 16 kDa proteolipids.

A cDNA (T3-L) encoding the 16 kDa subunit of vacuolar H(+)-ATPase was cloned from a cDNA library of rat liver. A polypeptide of 155 amino acids with a molecular mass of 15,807 Da (pI = 9.5) having four hydrophobic stretches was predicted. T3-L polypeptide was 92% and 100% identical with the 16 kDa proteolipid of bovine chromaffin granule and that of mouse, respectively. Antisera raised against the NH2-terminal of the T3-L polypeptide reacted positively with the membrane ghosts of rat liver tritosomes and the partially purified H(+)-ATPase thereof. Western blotting of subcellular fractions with the antisera showed high abundance of 16 kDa protein in the lysosomes, although a significant amount was also detected in the Golgi apparatus. Western blotting of rat tissues revealed high levels of 16 kDa proteolipid in the brain and the kidney. Northern blots with T3-L similarly showed considerably high expression of T3-L mRNA in the brain and the kidney. Southern hybridization of rat genomic DNA with T3-L showed at most three distinct bands, regardless of the stringency of hybridization and whether hybridization was performed with its subfragments. This suggests the possibility of multiple (at least three) homologous/identical genes encoding 16 kDa proteolipid. The possible presence and significance of isoforms of 16 kDa proteolipid in rats are discussed.

Amino Acid Sequence↗
PubMed1992

Induction and characterization of two types of ATPase on rat liver peroxisomes.

Clofibrate increased oligomycin-resistant ATPase activity in peroxisomes more than 17-fold (5.15 +/- 0.71 milliunits/mg protein) in rat liver. The activity was dependent on divalent cations (Mg2+ > Ca2+) with an optimum pH of 7.5. This activity was partially inhibited by N-ethylmaleimide (NEM), 4,4'-dithiocyanatostilbene-2,2'-disulfonic acid (DIDS), silicotungstic acid (STA), and high concentrations of N,N'-dicyclohexylcarbodiimide (DCCD). Proteinase K digestion of intact peroxisomes severely reduced the NEM-sensitive activity, but little affected the NEM-resistant activity. NEM-sensitive and -resistant ATPases showed Km values for ATP of 780 and 73 microM, respectively. The NEM-sensitive activity was inhibited completely by DIDS, 7-chloro-4- nitrobenzo-2-oxa-1,3-diazole (NBD-Cl), tributyltin chloride (TBT), and quercetin, and partially by DCCD and STA, whereas the NEM-resistant activity was totally insensitive to these chemicals except for STA. These activities had unique requirements for divalent cations, anions, and substrates, respectively. They were partially separated by gel filtration chromatography and had molecular masses of 520 kDa (NEM-sensitive enzyme) and 450 kDa (NEM-resistant enzyme), respectively.

Adenosine Triphosphatases↗
PubMed1992

Major ATPases on clofibrate-induced rat liver peroxisomes are not associated with 70 kDa peroxisomal membrane protein (PMP70).

We previously reported that novel Mg(2+)-ATPases were induced in rat liver peroxisomes by clofibrate administration and that these activities consisted of at least two types of enzymes, N-ethylmaleimide (NEM)-sensitive and -resistant. Here we present evidence that neither of these major peroxisomal ATPases is associated with the 70-kDa peroxisomal membrane protein (PMP70), because: (i) proteinase K treatment of peroxisomes resulted in inactivation of only NEM-sensitive ATPase, whereas disappeared PMP70 completely; (ii) NEM-sensitive ATPase activity was barely immunoprecipitated with anti-PMP70 IgG; (iii) the solubilized ATPases behaved differently from PMP70 on native PAGE; and finally (iv), the major peroxisomal ATPases were separated from PMP70 on gel filtration chromatography.

Adenosine Triphosphatases↗
PubMed1992

Characterization of muscarinic receptor subtypes on rat pancreatic acini: pharmacological identification by secretory responses and binding studies.

In order to identify subtypes of muscarinic receptor on the rat pancreas, the effects of new muscarinic receptor antagonists, [11-[[2-(diethylamino)-methyl]-1-piperidinyl]acetyl]-5, 11-dihydro-6H-pyrido[2,3-b][1,4]benzodiazepine-6-one (AF-DX 116) and 4-diphenylacetoxy-N-methylpiperadine-methiodide (4-DAMP), on amylase secretion stimulated by carbachol and binding of [3H]quinuclidinyl benzilate (QNB) were evaluated using isolated rat pancreatic acini. Atropine, pirenzepine, AF-DX 116 and 4-DAMP inhibited carbachol-stimulated amylase release in a dose-dependent manner. All these antagonists caused a concentration-dependent rightward shift of the dose-response curve for carbachol-stimulated amylase release without altering the maximal response. Schild plots revealed that pA2 values for atropine, pirenzepine, AF-DX 116 and 4-DAMP were 9.15, 6.78, 6.09 and 8.79, respectively. Every slope of Schild plots was not different from unity, suggesting that these antagonists act as competitive inhibitors. These antagonists also inhibited the binding of [3H]QNB in a dose-dependent manner. The inhibition constants were 1.21 x 10(-9) M (atropine), 1.26 x 10(-7) M (pirenzepine), 0.57 x 10(-6) M (AF-DX 116) and 2.75 x 10(-9) M (4-DAMP). Thus, the order of inhibitory potencies was atropine > or = 4-DAMP > pirenzepine > AF-DX 116. These findings suggest that 4-DAMP-sensitive M3 receptor may play an important role in the pancreatic exocrine functions.

Amylases↗
PubMed1992

Small GTP-binding proteins on rat liver lysosomal membranes.

GTP-binding proteins have been identified on the membranes of highly purified dextran-filled lysosomes (dextranosomes) and Triton-filled lysosomes (tritosomes) obtained from rat liver. Autoradiography of blots of lysosomal membrane proteins incubated with [alpha-32P]GTP revealed the presence of several specific GTP-binding proteins with a relative molecular mass (M(r)) predominantly in the range of 26-30 kDa. These GTP-binding proteins migrated slower in polyacrylamide gels than purified c-Ha-ras protein expressed in E. coli, whose apparent M(r) was 23 kDa in the same blot. The relative contents of GTP-binding proteins in lysosomal membranes were comparable or greater than that of plasma membranes and of microsomes. Chemical extraction showed that lysosomal GTP-binding proteins were more tightly associated with the membranes than with microsomal GTP-binding proteins. The possible involvement of lysosomal GTP-binding proteins in cellular functions including vacuolar (lysosomal) acidification and organellar dynamics are discussed.

Animals↗
PubMed1992

Three types of membranous ATPase on rat liver lysosomes.

At least three types of vanadate-insensitive membranous ATPase were identified on rat liver lysosomes: bafilomycin A1-sensitive Mg(2+)-ATPase (H(+)-ATPase), N-ethylmaleimide (NEM)-sensitive but bafilomycin A1-insensitive Mg(2+)-ATPase (ATPase I), and NEM-insensitive Ca2+/Mg(2+)-ATPase (ATPase II). They showed different sensitivity to chemicals and ions with apparent molecular masses of 700-800, 500-650, and 360 kDa, respectively. Of these membranous ATPases, H(+)-ATPase seemed to constitute only one tenth of the ATPase activity on rat liver lysosomes and to be the only ATPase that exposed its active site to the cytoplasmic side of the lysosomal membranes.

Adenosine Triphosphatases↗
PubMed1992

Inhibition of gastric glucosamine synthetase activity by oxygen radicals: a possible cause of decreased mucosal protective capacity.

To clarify the role of oxygen radicals in the mucus metabolism of the gastrointestinal tract, the effect of oxygen radicals on the activity of glucosamine synthetase, the rate-limiting enzyme of mucus synthesis, was investigated using homogenate derived from rat gastric mucosa. The simultaneous addition of both xanthine and xanthine oxidase caused a significant inhibition of the enzyme activity, and this decrease was counteracted by catalase, but not by superoxide dismutase. Hydrogen peroxide also caused a significant decrease in the enzyme activity; and this effect of hydrogen peroxide was counteracted by catalase and dithiothreitol, but not by mannitol, dimethyl sulfoxide and reduced glutathione. The inhibition of glucosamine synthetase activity by oxygen radicals is considered to be caused by the oxidation of sulfhydryl groups of the enzyme molecule. The present results also suggest that oxygen radicals in the gastrointestinal tract may induce the suppression of a protective mechanism of the gastric mucosa by inhibiting glucosamine synthesis activity.

Animals↗
PubMed1991

Induction of neurite outgrowth of PC12 cells by an inhibitor of vacuolar H(+)-ATPase, bafilomycin A1.

Bafilomycin A1, a selective inhibitor of vacuolar H(+)-ATPase, induced neurite outgrowth of PC12 cells dose- and time-dependently: more than 50% of the cells extended neurite-like spikes after 24 h treatment with 100 nM bafilomycin A1. Its dose-response ran roughly parallel to that of a bafilomycin A1-induced lysosomal pH increase. It was inhibited by LiCl, an inhibitor of the phosphorylation of microtubule-associated proteins and, like nerve growth factor (NGF)-induced neurite outgrowth, it was also inhibited by cycloheximide and actinomycin D. But, unlike the NGF-effect, it was not associated with rapid induction of c-fos.

Animals↗
PubMed1991

Presence of influenza virus-reactive glycophorins other than glycophorin A in human erythrocyte membranes.

The reactivities against seven hemagglutinins including influenza A and B viruses of six sialoglycoprotein (glycophorin) fractions, M-Frs.1-3 and N-Frs.1-3, separated from human OMs and ONs erythrocyte membranes by a combination of the LIS-phenol method and gel filtration were studied. The serological results show that M-Fr.1 and N-Fr.1 were glycophorins AM and AN, respectively, the reactivities against influenza A and B viruses of both M-Fr.2 and N-Fr.2 which contained glycophorins B and C were remarkably higher than that of glycophorin A and the reactivities against influenza viruses of both M-Fr.3 and N-Fr.3 which contained glycophorins B and D were considerably lower than that of glycophorin A.

Amino Acids↗