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Biomedical subjects

T Oshima

Publications and source records attributed to T Oshima.

At least 415 records · Page 23Linked to original sources
PubMed1990

Human malignant melanoma cell line (HMV-II) for isolation of influenza C and parainfluenza viruses.

HMV-II, a human malignant melanoma cell line, was compared with other cell lines (MDCK, Vero, and LLC-MK2) and primary cultures of monkey kidney (PMK) cells for the isolation and quantification of influenza and parainfluenza viruses. HMV-II cells were superior to MDCK and LLC-MK2 cells in quantification of the influenza C virus and were used successfully in the isolation of the virus from clinical specimens. The HMV-II cell line was also more sensitive for isolating parainfluenza viruses from clinical specimens than were Vero and PMK cells; there was, however, no significant difference in the quantification of the viruses among these cultures. As far as influenza A and B viruses were concerned, the HMV-II cell line was significantly less sensitive than MDCK cells, and no virus was isolated from clinical specimens with HMV-II cells. Thus, HMV-II cells are useful for the isolation of influenza C and parainfluenza viruses as an alternative to embryonated hen's eggs and PMK cells.

Animals↗
PubMed1990

Abnormal calcium handling by platelets of spontaneously hypertensive rats.

There is controversy as to whether platelet intracellular free calcium ([Ca2+]i) is increased in spontaneously hypertensive rats (SHR) as compared with Wistar-Kyoto (WKY) rats. Discrepant results may be due to methodological problems including platelet activation during the collection process and leakage of intracellular dye used for [Ca2+]i measurement. To provide further insight into this problem, [Ca2+]i was estimated in fura-2-loaded platelets isolated from eight SHR and seven WKY rats at 12-14 weeks of age by using a two-syringe blood collection method and a correction method for fura-2 leakage. Basal [Ca2+]i was higher in SHR than in WKY rats (61.6 +/- 5.6 vs. 54.0 +/- 3.9 nM, p less than 0.02). However, the difference disappeared when a correction for fura-2 leakage was not used (109.7 +/- 18.4 vs. 94.9 +/- 9.2 nM, p less than 0.1). Thus, differences in [Ca2+]i between SHR and WKY rats may be obscured if dye leakage from platelets is not taken into account. Thrombin (0.1 units/ml) induced a rise in [Ca2+]i that was greater in SHR than WKY rats, both in the presence (491.4 +/- 31.6 vs. 377.5 +/- 21.7 nM, p less than 0.002) and absence (264.9 +/- 33.6 vs. 228.2 +/- 30.1 nM, p less than 0.05) of calcium in the media. These results indicate that thrombin-stimulated calcium influx as well as discharge of calcium from intracellular stores is increased in SHR platelets. Thus, under both basal and stimulated conditions, platelet calcium handling is abnormal in the SHR.

Aminoquinolines↗
PubMed1990

Medium hyposmolarity stimulates prolactin secretion in GH4C1 cells by inducing an increase in cytosolic free calcium.

Extracellular hyposmolarity is a potent direct stimulus for hormone secretion for which a mechanism has not been delineated. The importance of plasmalemma Ca2+ permeability in this phenomenon in pituitary tumor-derived GH4C1 cells was evaluated by comparing the dynamics of changes in cytosolic free Ca2+ concentration [( Ca2+]i) with those of PRL secretion. At a normal physiological concentration of extracellular Ca2+ (1.5 mM), hyposmolarity induced a striking rise in both [Ca2+]i and PRL secretion, which was proportional to the stimulus between 0.50% reduction in medium osmolarity. Thirty percent hyposmolarity induced a 3-fold rise in [Ca2+]i and a 5-fold rise in PRL secretion above the basal level. These effects did not occur in cells incubated in a medium with a Ca2+ concentration lower than 30 microM. In cells incubated in 1.5 mM Ca2+, the Ca2(+)-channel antagonists, nifedipine and verapamil, significantly inhibited hyposmolar-induced increases in [Ca2+]i and PRL secretion. These data suggest that in GH4C1 cells medium hyposmolarity causes a burst of PRL secretion that depends on a similar preceding rise in [Ca2+]i produced by extracellular Ca2+ influx, most of which passes through dihydropyridine-sensitive Ca2(+)-channels.

Animals↗
PubMed1990

Reduced erythrocyte deformability in anemic rats with adjuvant arthritis.

Erythrocytes in anemic rats with adjuvant arthritis (AA) were less deformable compared with normal rats. Swelling of the spleen was noticed in anemic rats with AA. The treatment of anemic rats with recombinant human erythropoietin (r-HuEPO; 30 and 100 U/kg, i.v., for 5 days) resulted in a normalization of both the anemia and erythrocyte deformability. It is suggested that erythrocytes with reduced deformability may be sequestered by endothelial slits of the spleen, which may play a causative role in the anemia in rats with AA.

Anemia↗
PubMed1990

Reduction of infarct size and infiltration of polymorphonuclear leukocytes by a thromboxane synthetase inhibitor. Studies in a rabbit ischemic heart model.

The effect of sodium 6-(2-(1-(1H)-imidazolyl)methyl-4,5-dihydrobenzo(b) thiophene)carboxylate (RS-5186), a potent and long acting thromboxane synthetase inhibitor in vitro and in vivo, on infarct size and on the infiltration of polymorphonuclear leukocytes (PMNs), was studied in a rabbit coronary artery occlusion (1 h)--reperfusion (0.5 h or 3 h) model. The infarcted region was stained with triphenyltetrazolium, and the ratio of infarcted area/left ventricular area was calculated. The infiltration of PMNs into the infarcted region was determined by measuring the PMNs specific enzyme, myeloperoxidase (MPO) activity. In the vehicle treated group, infarct size and MPO activity were increased with increased reperfusion time from 0.5 h to 3 h (infarct size: 15.3 +/- 2.7 to 25.2 +/- 3.2%; MPO activity: 255 +/- 51 to 825.3 +/- 169.4 units/g wet weight). There was also a significant correlation (r = 0.90, p less than 0.01) between the infarct size and MPO activity. In contrast, in the RS-5186 treated group (2 mg/kg i.v.), both infarct size and MPO activity did not increase with prolongation of the reperfusion period (infarct size: 12.8 +/- 5.5 to 10.3 +/- 3.6%; MPO activity: 318.8 +/- 36.7 to 381.2 +/- 72.6 units/g wet weight). In 0.5 h reperfused samples, there was no significant difference in infarct size or in MPO activity between the vehicle treated group and RS-5186 treated group.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

A novel a-type terminal oxidase from Sulfolobus acidocaldarius with cytochrome c oxidase activity.

Cytochrome C oxidase was solubilized with a nonionic detergent n-decanoyl-N-methyl glucamide from the membranes of Sulfolobus acidocaldarius, a thermoacidophilic archaebacterium, and was purified. The enzyme oxidized horse heart cytochrome C with a Vmax of 63 mumols/min/mg at 50 degrees C. The activity was sensitive to cyanide. The enzyme also catalyzed oxygen uptake detergent on N, N, N', N'-tetramethyl p-phenylene diamine. An apparent molecular mass was estimated to be 150 kDa. The enzyme is composed of three subunits of 37, 23 and 14 kDa. Spectral characteristics were similar to typical bacterial aa3 except for the presence of a novel 583 nm peak observed in reduced minus oxidized difference spectrum.

Archaea↗
PubMed1989

A gene encoding the proteolipid subunit of Sulfolobus acidocaldarius ATPase complex.

An analysis of genes for the major two subunits of the membrane-associated ATPase from an acidothermophilic archaebacterium, Sulfolobus acidocaldarius, suggested that it belongs to a different ATPase family from the F1-ATPase (Denda, K., Konishi, J., Oshima, T., Date, T., and Yoshida, M. (1988) J. Biol. Chem. 263, 17251-17254). In the same operon of the above two genes we found a gene encoding a very hydrophobic protein of 101 amino acids (Mr = 10,362). A proteolipid was purified from the membranes of this bacteria in which partial amino acid sequences matched with the sequence deduced from the gene. Significant amino acid sequence homology and a similar hydropathy profile appeared when the sequence was compared with the 8-kDa proteolipid subunit of F0F1-ATPases. It is about 30 amino acids larger than the 8-kDa proteolipid and has a small (11-amino acid) repeat sequence. However, it is distinct from the 16-kDa proteolipid subunit of an eukaryotic vacuolar H+-ATPase (Mandel, M., Moriyama, Y., Hulmes, J.D., Pan, Y.-E., Nelson, H., and Nelson, N. (1988) Proc. Natl. Acad. Sci. U.S.A. 85,5521-5524).

Adenosine Triphosphatases↗
PubMed1989

A highly stable NADP-dependent isocitrate dehydrogenase from Thermus thermophilus HB8: purification and general properties.

NADP-dependent isocitrate dehydrogenase (EC 1.1.1.42) was purified to electrophoretic homogeneity from an extremely thermophilic bacterium, Thermus thermophilus HB8, and shown to be a dimeric protein of molecular weight 115,000, with a pI of 5.5. The amino acid composition of the present enzyme was similar to that reported for other bacterial counterparts, except for a high Arg/Lys ratio and a low Cys content. Divalent cations, such as Mn2+ and Mg2+, were essential for activity. The optimal pH was 7.8 at 55 degrees C. The Km values for NADP and D-isocitrate were 6.3 and 8.8 microM, respectively, with a Vmax of 77.6 mumol/min per mg at 55 degrees C. NAD was able to replace NADP with low efficiency. Backward reaction at 40 degrees C indicated that the Km value for 2-oxoglutarate was 63 microM with a Vmax of 4% that of the forward reaction at that temperature. The enzyme was highly stable against high temperature and denaturing reagents.

Amino Acids↗
PubMed1989

Synthesis and thromboxane synthetase inhibitory activity of di- or tetrahydrobenzo[b]thiophenecarboxylic acid derivatives.

1-Imidazolylalkyl-substituted di- or tetrahydrobenzo[b]thiophenecarboxylic acid derivatives and related compounds were synthesized from tetrahydrobenzo[b]thiophene derivatives (1 or 4) in order to study the structure-activity relationships of the inhibition of thromboxane A2 synthetase in vitro. Sodium 2-(1-imidazolylmethyl)-4,5-dihydrobenzo[b]thiophene-6-carboxylate (26) and 2-(1-imidazolylmethyl)-4,5,6,7-tetrahydrobenzo[b]thiophene-6-carbo xylic acid hydrochloride (28) showed the most potent and specific activity in vitro for thromboxane A2 synthetase inhibition.

Animals↗
PubMed1989

Evolution of the vacuolar H+-ATPase: implications for the origin of eukaryotes.

Active transport across the vacuolar components of the eukaryotic endomembrane system is energized by a specific vacuolar H+-ATPase. The amino acid sequences of the 70- and 60-kDa subunits of the vacuolar H+-ATPase are approximately equal to 25% identical to the beta and alpha subunits, respectively, of the eubacterial-type F0F1-ATPases. We now report that the same vacuolar H+-ATPase subunits are approximately equal to 50% identical to the alpha and beta subunits, respectively, of the sulfur-metabolizing Sulfolobus acidocaldarius, an archaebacterium (Archaeobacterium). Moreover, the homologue of an 88-amino acid stretch near the amino-terminal end of the 70-kDa subunit is absent from the F0F1-ATPase beta subunit but is present in the alpha subunit of Sulfolobus. Since the two types of subunits (alpha and beta subunits; 60- and 70-kDa subunits) are homologous to each other, they must have arisen by a gene duplication that occurred prior to the last common ancestor of the eubacteria, eukaryotes, and Sulfolobus. Thus, the phylogenetic tree of the subunits can be rooted at the site where the gene duplication occurred. The inferred evolutionary tree contains two main branches: a eubacterial branch and an eocyte branch that gave rise to Sulfolobus and the eukaryotic host cell. The implication is that the vacuolar H+-ATPase of eukaryotes arose by the internalization of the plasma membrane H+-ATPase of an archaebacterial-like ancestral cell.

Amino Acid Sequence↗
PubMed1989

Expression of multiple tau isoforms and microtubule bundle formation in fibroblasts transfected with a single tau cDNA.

Tau proteins are a class of low molecular mass microtubule-associated proteins that are specifically expressed in the nervous system. A cDNA clone of adult rat tau was isolated and sequenced. To analyze functions of tau proteins in vivo, we carried out transfection experiments. A fibroblast cell line, which was transfected with the cDNA, expressed three bands of tau, while six bands were expressed in rat brain. After dephosphorylation, one of the three bands disappeared, demonstrating directly that phosphorylation was involved in the multiplicity of tau. Morphologically, we observed a thick bundle formation of microtubules in the transiently and stably tau-gene-transfected cells. In addition, we found that the production of tubulin was prominently enhanced in the stably transfected cells. Thus, we suppose that tau proteins promote polymerization of tubulin, form bundles of microtubules in vivo, and play important roles in growing and maintaining nerve cell processes.

Amino Acid Sequence↗
PubMed1989

Isolation and characterization of temperature-sensitive mutations in the RAS2 and CYR1 genes of Saccharomyces cerevisiae.

The yeast Saccharomyces cerevisiae contains two ras homologues, RAS1 and RAS2, whose products have been shown to modulate the activity of adenylate cyclase encoded by the CYR1 gene. To isolate temperature-sensitive mutations in the RAS2 gene, we constructed a plasmid carrying a RAS2 gene whose expression is under the control of the galactose-inducible GAL1 promoter. A ras1 strain transformed with this plasmid was subjected to ethyl methanesulfonate mutagenesis and nystatin enrichment. Screening of approximately 13,000 mutagenized colonies for galactose-dependent growth at a high temperature (37 degrees) yielded six temperature-sensitive ras2 (ras2ts) mutations and one temperature-sensitive cyr1 (cyr1ts) mutation that can be suppressed by overexpression or increased dosage of RAS2. Some ras2ts mutations were shown to be suppressed by an extra copy of CYR1. Therefore increased dosage of either RAS2 or CYR1 can suppress the temperature sensitivity caused by a mutation in the other. ras1 ras2ts and ras1 cyr1ts mutants arrested in the G1 phase of the cell cycle at the restrictive temperature, and showed pleiotropic phenotypes to varying degrees even at a temperature permissive for growth (25 degrees), including slow growth, sporulation on rich media, increased accumulation of glycogen, impaired growth on nonfermentable carbon sources, heat-shock resistance, impaired growth on low concentrations of glucose, and lithium sensitivity. Of these, impaired growth on low concentrations of glucose and sensitivity to lithium are new phenotypes, which have not been reported for mutants defective in the cAMP pathway.

Adenylyl Cyclases↗
PubMed1989

Polyamines of sulfur-dependent archaebacteria and their role in protein synthesis.

Several strains of the sulfur-dependent archaebacterium, Sulfolobus, were analyzed for their polyamine content. Caldine (norspermidine), spermidine, and thermine were found to be major components in all of the cells tested. The most abundant polyamine in all cultures examined was spermidine. The Langworthy strain had the highest spermine content, whereas S. acidocaldarius strain no. 7 was devoid of this polyamine. Cultures of strain no. 7 grown at 70 degrees C were rich in spermidine and caldine (triamines) and the thermine: spermidine ratio was much lower than that of cultures grown at 78 degrees C. Equal amounts of thermine and spermidine were present in strain DSM 1616. Preincubation of Langworthy strain extracts at 10 degrees C did not overcome the requirement for polyamines in protein synthesis. Putrescine exerted a concentration-dependent inhibition of the spermine-induced stimulation of protein synthesis at 70 degrees C. Increasing concentrations (6 and 9 mM) of spermine and thermine progressively inhibited poly(U)-dependent phenylalanine incorporation at 45 degrees C to about the same extent, whereas the same concentrations of these polyamines had little effect on the reaction at 70 degrees C. Although 3 mM spermine had only a slight stimulatory effect on the attachment of phenylalanine to tRNA at 65 degrees C, this polyamine had a pronounced effect on the formation of 70S ribosomes in a standard buffer containing 10 mM Mg2+. Increasing the Mg2+ concentration to 30 mM in the absence of spermine was even more effective in causing the reassociation of subunits to form 70S particles.

Amino Acids↗
PubMed1989

Lactone and cyclic ether analogues of platelet-activating factor. Synthesis and biological activities.

Six-membered lactone and tetrahydropyran analogues of platelet-activating factor (PAF), 4-11, and related antagonistic derivatives 41-46 were synthesized. None of the delta-lactones 4-7 showed PAF-like activities, while the corresponding cyclic ethers 8, 9 and 11 were slightly active. Some of the cyclic antagonists showed more potent inhibitory activities than the open chain antagonist CV-3988 against platelet aggregation (rabbit platelet-rich plasma, IC50) and hypotension (rat, ID50) induced by C16-PAF: e.g. dl-3-[6-[O-(trans-3-heptadecylcarbamoyloxytetrahydropyran-2- yl)methyl]phosphonoxy]hexylthiazolium (inner salt) (41d) (IC50 5.5 x 10(-7) M, ID50 0.046 mg/kg, i.v.); dl-3-[5-[O-(cis-3-heptadecylcarbamoylthiotetrahydropyran-2- yl)methyl]phosphonoxy]pentylthiazolium (inner salt) (43c) (IC50 5.7 x 10(-7) M, ID50 0.076 mg/kg, i.v.).

Animals↗
PubMed1989

Synthesis and antagonistic activities of enantiomers of cyclic platelet-activating factor analogues.

Enantiomers of platelet-activating factor (PAF) antagonists, 3-(6-[O-(trans-3-heptadecylcarbamoyloxytetrahydropyran-2-yl)methyl ] phosphonoxy)hexylthiazolium (inner salt) (3), 3-[5-(trans-3-heptadecylcarbamoyloxytetrahydropyran-2-yl) methoxycarbonylamino]pentylthiazolium bromide (4) and 3-(5-[O-(cis-3-heptadecylcarbamoylthiotetrahydropyran-2-yl) methyl]phosphonoxy)pentylthiazolium (inner salt) (5), were synthesized, starting from (2R,2R)- and (2S,2S)-tartaric acid. Antagonistic activities of these compounds against C16-PAF were measured in vitro (rabbit platelet aggregation, IC50) and in vivo (hypotension in rats, ID50). In these three enantiomeric pairs, the (3S)-(tetrahydropyran numbering) enantiomers were one order more potent than the (3R)-isomers: (2R,3S)-3a (R-74,654), IC50 0.59 microM and ID50 0.054 mg/kg, i.v.; (2S,3R)-3b, IC50 4.7 microM and ID50 0.30 mg/kg, i.v.; (2R,3S)-4a, IC50 0.20 microM and ID50 0.032 mg/kg, i.v.; (2S,3R)-4b, IC50 2.2 microM and IC40 0.21 mg/kg, i.v.; (2R,3R)-5a, IC50 1.1 microM and ID50 0.92 mg/kg, i.v.; (2S,3S)-5b (R-74,717), IC50 0.27 microM and ID50 0.064 mg/kg, i.v.

Chemical Phenomena↗
PubMed1989

Application of ion-pair high performance liquid chromatography for analysis of hyoscyamine and scopolamine in solanaceous crude drugs.

A new ion-pair high-performance liquid chromatographic method for the analysis of hyoscyamine and scopolamine in various kinds of crude drugs derived from solanaceous plants was evaluated using sodium dodecyl sulfate as a counter ion. A reversed-phase chromatographic system consisting of a chemically bonded ODS silica gel column with phosphate buffer (pH 2.5)-acetonitrile (65:35) containing 17.5 mM sodium dodecyl sulfate as the mobile phase was used. Hyoscyamine and scopolamine in crude drugs derived from Scopolia, Atropa, Hyoscyamus and Datura species were separated from other compounds in the crude drugs and determined within 20 min after direct injection of the solution extracted with the mobile phase. The results for various kinds of samples are presented.

Atropine↗
PubMed1989

Sodium chloride sensitivity, intracellular sodium concentration in erythrocytes and lymphocytes, and renin profile in essential hypertension.

In order to clarify the possible relationship between changes in blood pressure after salt loading, membrane sodium transport and renin profile, 19 patients with essential hypertension (8 patients with low renin hypertension and 11 patients with normal renin hypertension), admitted to our hospital, were studied. We also examined the correlation of changes in intracellular sodium concentration after salt loading between erythrocytes and lymphocytes. After a control period of one week, all subjects were placed on a low salt intake for one week followed by one week of a high salt intake. Percent increases in mean blood pressure and intracellular sodium concentration in erythrocytes and in lymphocytes after salt loading were greater in low renin hypertensive patients than in normal renin hypertensives. Percent changes in intracellular sodium concentration in erythrocytes inversely correlated with those in ouabain sensitive sodium efflux rate constant and positively correlated with those in intracellular sodium concentration in lymphocytes. These results suggest that an increase in sodium chloride sensitivity of blood pressure in patients with low renin hypertension may be due to the inhibition of Na+-K+ pump in vascular smooth muscle cell membrane.

Adult↗