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Biomedical subjects

T Hase

Publications and source records attributed to T Hase.

At least 145 records · Page 8Linked to original sources
PubMed1989

A comparative study of entry modes into C6/36 cells by Semliki Forest and Japanese encephalitis viruses.

The entry modes of Semliki Forest virus and Japanese encephalitis virus into C6/36 cells were compared by electron microscopic observation. At physiological pH, the two viruses showed characteristically different entry modes. Following attachment to the plasma membrane, many SF virions appeared within plasma membrane invaginations and cytoplasmic vesicles; on the other hand, JE virions remained to be found exclusively at the cell surface, with no virions appearing within cytoplasmic vesicles. Electron microscopic observation, therefore, indicated that SF virus entered C6/36 cells by receptor-mediated endocytosis, while JE virus penetrated the cells at the surface and disintegrated at or near the adsorption sites. At pH 5.8, SF virus also entered C6/36 cells by direct penetration at the cell surface. On the basis of the present and other findings, the following working hypotheses are presented for future investigations: (a) at physiological pH, the fusion protein of SF virus is in an inactive state and needs to be activated by acidic pH within the endosome in order to act on the host-cell membrane, but that of JE virus is in an active state and is capable of dissolving the host plasma membrane at the cell surface immediately after the attachment; (b) the states of viral fusion proteins (inactive or active) at the time of viral attachment to the cell surface determine which of the two entry modes these viruses follow.

Animals↗
PubMed1989

Flavivirus entry into cultured mosquito cells and human peripheral blood monocytes.

The entry modes of Japanese encephalitis (JE) and dengue-2 (DEN-2) viruses into C6/36 mosquito cells and of DEN-2 virus into human peripheral blood monocytes in vitro were studied. Inoculation of either JE or DEN-2 virions into C6/36 cells resulted in direct penetration of the virions into the cytoplasm at the cell surface in 3 stages. At stage 1, virions attached to the plasma membrane of host cells by their envelope spikes; at stage 2, the virion envelopes approximated to and eventually overlapped the host plasma membrane, and in the process the plasma membrane at the attachment sites dissolved; and, at stage 3, virions penetrated into the cytoplasm through the plasma-membrane disruptions created at the adsorption sites. Virions themselves apparently disintegrated at or near the penetration sites, for no virions were seen in the deeper cytoplasm. Coated pits did not form at the virion attachment sites, and virion-containing vesicles were not found in the cytoplasm. In the entry of DEN-2 virus into human peripheral blood monocytes, virions were found, adsorbed onto the external surface of the plasma membrane and attached to the luminal surface of macropinocytic vacuolar membranes. The latter apparently occurred as the result of ruffling and macropinocytic activities of the cells. At both sites virions penetrated into the cytoplasm through the plasma or vacuolar membrane in the same manner as they did through the plasma membrane of C6/36 cells. No evidence of viral entry by receptor-mediated endocytosis was observed. Implications of the entry mode of the mosquito cell-generated DEN-2 virus into human peripheral blood monocytes to an early process of natural, mosquito-transmitted infection is discussed.

Adsorption↗
PubMed1989

Aspartate aminotransferase from Panicum maximum Jacq. var. trichoglume Eyles, a C4 plant: purification, molecular properties, and preparation of antibody.

Extracts of the leaf tissue of Panicum maximum Jacq. var. trichoglume Eyles (a phosphoenolpyruvate carboxykinase type of C4 plant) were examined and at least two isoforms of aspartate aminotransferase (EC 2.6.1.1), with different electrophoretic mobilities, were detected. The predominant isoform was purified to homogeneity from mesophyll cells. The purification procedure included fractionation with ammonium sulfate followed by chromatography on diethylaminoethyl-cellulose, Sephacryl S-300, and hydroxyapatite. The purified enzyme had specific activities of 182 and 165 mumol/min/mg protein, measured in terms of the synthesis of oxaloacetate and aspartate, respectively, at pH 8.0. The enzyme, with an apparent molecular size of 100 kDa, appears to be a dimer of a single polypeptide with a molecular size of 42 kDa. Mono specific polyclonal antibodies were raised against the 42-kDa polypeptide. Only a single stained band was detected in extracts of whole leaves by immunoblot analysis with this antibody after two-dimensional polyacrylamide electrophoresis. Furthermore, no difference in mobility was observed between the enzymes extracted from mesophyll and bundle sheath cells on native polyacrylamide gels. These findings are discussed in relation to the other isoform in the leaves of this species.

Antibodies↗
PubMed1989

Flaviviruses can mediate fusion from without in Aedes albopictus mosquito cell cultures.

Flavivirus-induced polykaryocytes were detected in monolayers of Aedes albopictus (clone C6/36) mosquito cells as early as 20 min after adsorbing virus to these cells. A high multiplicity of infection with dengue (DEN)-1, 2, 3, 4, Japanese encephalitis, and yellow fever viruses was required to demonstrate fusion from without (FFWO) with these flaviviruses. Optimal conditions for FFWO included exposure of adsorbed virus to pH 6.0 and an incubation temperature of 39 degrees C. DEN-2 monoclonal antibodies to the envelope E glycoprotein inhibited cell fusion, whereas monoclonal antibodies to the prM and NS1 proteins did not inhibit cell fusion. These results indicate that flaviviruses cause FFWO soon after adsorption to C6/36 mosquito cells and the process is most likely mediated by the virion envelope E glycoprotein.

Aedes↗
PubMed1989

Precise determination of the mitochondrial import signal contained in a 70 kDa protein of yeast mitochondrial outer membrane.

A major 70 kDa protein of the yeast mitochondrial outer membrane is coded by a nuclear gene, synthesized on cytoplasmic ribosomes, and transported to the mitochondrial outer membrane. In order to investigate in detail the information necessary for localizing the 70 kDa protein at the outer membrane, we have examined the intracellular and intramitochondrial location of fusion proteins which consist of various lengths of the amino-terminal region of the 70 kDa protein with an enzymatically active beta-galactosidase. The results indicate that the extreme amino-terminal 12 amino acids of the 70 kDa protein function as a targeting sequence, whereas the subsequent uncharged region (up to residue 29) is necessary for "stop-transfer" and "anchoring" functions. Moreover, we have found that a fusion protein which contained the amino-terminal 19 amino acids of the 70 kDa protein is localized on the outer membrane as well as in the matrix space. Changes in the dual localization of this fusion protein accompanied its overproduction or expression in a respiration-deficient yeast mutant.

Base Sequence↗
PubMed1989

Protein sorting between the outer and inner mitochondrial membranes: submitochondrial localization of cytochrome c1 whose presequence is replaced by the amino-terminal region of a 70 kDa outer membrane protein.

The amino-terminal region of a 70 kDa mitochondrial outer membrane protein of yeast and the presequence of cytochrome c1, an inner membrane protein exposed to the intermembrane space, are thought to be responsible for localizing the proteins in their final destinations after synthesis in the cytosol. Gene fusion experiments were used to identify signals that are responsible for protein sorting between the outer and inner mitochondrial membranes. The submitochondrial localization of cytochrome c1 whose presequence was replaced by the amino-terminal region of the 70 kDa mitochondrial outer membrane protein has been investigated. We have also used an in vivo complementation assay to determine whether or not a 70k-cyt c1 fusion protein is functional. Both the first half and all of the presequence of cytochrome c1 can be replaced by the amino-terminal 12 or 29 residues of the 70 kDa protein for transport to the inner membrane and functional assembly into succinate-cytochrome c reductase. However, replacements by the amino-terminal 61 residues of the 70 kDa protein result in exclusive localization of the fusion proteins to the outer membrane, and the fusions cannot be assembled into the enzyme complex. These data indicate that a mitochondrial targeting signal alone is sufficient to direct cytochrome c1 of mature size to the inner membrane.

Animals↗
PubMed1989

Localization of ferredoxin isoproteins in mesophyll and bundle sheath cells in maize leaf.

Four ferredoxin isoproteins were identified in the C(4) plant Zea mays L. by analysis of extracts from leaves, mesocotyls, and roots of the young seedlings. The relative amounts of the isoproteins isolated from the photosynthetic and nonphotosynthetic organs were different. All the isoproteins were present in the leaves of green and etiolated plants, whereas two out of the four isoproteins were not detected in the roots or in the mesocotyls. During the greening of etiolated seedlings, the level of the two isoproteins unique to the leaf increased markedly. Analysis of the cellular and subcellular distribution of the two major leaf isoproteins showed that one isoprotein was present in the chloroplasts of both mesophyll and bundle sheath cells, whereas the other was only found in the chloroplasts of bundle sheath cells. This is the first report of the cell-specific expression of ferredoxin isoproteins in the leaves of a C(4) plant.

Journal Article↗
PubMed1989

Sparsomycin analogs. VI. Synthesis and antitumor activity of octylsparsomycin analogs.

Five sparsomycin analogs (9-13) were prepared and examined for their ability to inhibit deoxyribonucleic acid (DNA) synthesis in L5178Y lymphoma cells. All of the compounds showed significant activity in the DNA synthesis assay. The compounds having Rc configuration exhibited almost the same activities independently of the configuration at the sulfoxide sulfur atom. Among the Sc isomers, the Rs configuration was advantageous for the appearance of activity.

Animals↗
PubMed1989

[Biological characteristics of plasmid carrying a repeated deoxyribonucleic acid sequence].

It was found that a plasmid which had a foreign deoxyribonucleic acid (DNA) between two repeated sequences did not multiply in E. coli recBCsbcB, even if it multiplied in wild-type E. coli, E. coli recBC or E. coli recBCsbcBrecF when the insert was longer than 351 base pair. The multiplication of these plasmids were, however, inhibited when a plasmid expressing recF gene was introduced into E. coli recBCsbcBrecF. The inviability of the plasmid carrying the repeated sequence in E. coli recBCsbcB was discussed by the mechanism of recombination, and the functions of recF, recBC and sbcB were speculated. When E. coli recBC was transformed with pDR1 which was a derivative of pBR322 carrying a directly repeated sequence between which a DNA fragment derived from plasmid R6K with its origin was inserted, the intramolecular recombinant appeared. The recombinant recovered was, however, only the plasmid which had the replication origin of pBR322. The result suggests that pBR322 is compatible with pDR1 but R6K is not. The replication origin of R6K seems to be preferrentially used by pDR1.

DNA, Bacterial↗
PubMed1989

[In vitro replication of plasmid pKYM].

The crude extract (fraction II) prepared from E. coli could replicate plasmid pKYM, only when the extract contained the rep protein which was produced by the plasmid and essential for its multiplication in vivo. The intermediate of replication was accumulated when a dideoxynucleotide triphosphate was added to the reaction mixture. By analyzing the intermediate, the initiation site of the deoxyribonucleic acid replication and the direction of replication could be determined. The replication initiated inside the ori region of pKYM and the direction was unidirectional. The analysis also suggested that the synthesis of the lagging strand stopped at almost the same site as the initiation site.

Adenosine Triphosphatases↗
PubMed1989

[Factors affecting the setting time of zinc oxide-eugenol impression materials--the influence of humidity and temperature to the reaction velocity].

Zinc oxide-eugenol paste are widely used in clinical dentistry, principally for impression of non-undercut edentulous ridges, or bite taking materials. However it has been realized by those who use these paste that different products, direction for mixing, or different conditions for mixing, have different characteristics. An experiment have been made to observe the influence of different conditions for mixing to the setting time. Zinc oxide-eugenol impression pastes were mixed in accordance with the manufacturer's instruction when supplied. The condition for mixing was at temperature of 15 +/- 1, 20 +/- 1, 25 +/- 1, 30 +/- 1 degrees C and at humidity of 40 +/- 5, 70 +/- 5, 90 +/- 5%. The setting time (a initial setting time, a final setting time) was defined in the A.D.A. specification No. 16. The following results were obtained. 1. A higher temperature and humidity shortened the initial setting time of all paste. 2. A higher temperature and humidity shortened slightly the time interval between a initial and a final setting time of all paste. 3. In clinical use, sample C is better than other ones, so that a setting time of the sample is property for impression making.

Dental Impression Materials↗
PubMed1989

Metabolism of antipyrine and m-xylene in rats after prolonged pretreatment with xylene alone or xylene with ethanol, phenobarbital or 3-methylcholanthrene.

1. The metabolic disposition of antipyrine (AP) and m-xylene (XYL) has been studied in rats pretreated for a prolonged period with XYL, dosed alone or in combination with ethanol, phenobarbital (PB), or 3-methylcholanthrene (MC). 2. XYL inhalation exposure at 300 ppm in air (7 h/day, 4 days/week, for 1 or 4 weeks) did not alter the total 24-h recovery of AP and its major metabolites in urine, but the excretion profile changed compared with controls: 3-hydroxymethylantipyrine (3-HMA) increased (less than or equal to 14%, P less than 0.001), norantipyrine (NORA) (less than or equal to 23%, P less than 0.01) and AP (less than or equal to 53%, P less than 0.01) decreased. 4-Hydroxyantipyrine (4-OHA) was unchanged. 3. Oral dosage of XYL at 800 mg/kg per day (5 days/week, for 12 days) altered the metabolic disposition of AP similarly to inhalation. 4. XYL + ethanol did not alter the xylene-type effect on AP metabolism. This was at variance with the changes following XYL + PB and, to a greater extent, XYL + MC pretreatments: 4-OHA increased (53-74%, P less than 0.01), 3-HMA (11-42%, P less than 0.05) and AP (greater than or equal to 50%, P less than 0.05) decreased. The effect on NORA was less clear. 5. XYL pretreatment accelerated metabolic disposition of its major urinary metabolite, methylhippuric acid (MHA) and formation of thioethers. 6. Thioether excretion in 24 h urine was enhanced about 10-fold after XYL inhalation and 20-fold after oral administration. Only XYL + PB treatment enhanced further the excretion of xylene-derived thioethers (P less than 0.05). 7. Drug-metabolizing activity (phase I and II reactions) in liver, lung and kidney showed that the treatments resulted in marked and differential biochemical alterations. 8. In conclusion, m-xylene enhanced the rate of its own metabolism and induced differential changes on urinary AP metabolite profile depending on the pretreatment.

Administration, Inhalation↗
PubMed1989

[Bactericidal action of lomefloxacin a new pyridonecarboxylic acid derivative].

Lomefloxacin (NY-198) [(+/-)-1-ethyl-6,8-difluoro-1,4-dihydro-7-(3-methyl-1-piperazinyl)-4-oxo -3- quinolinecarboxylic acid hydrochloride] strongly inhibited the growths of not only Gram-negative Escherichia coli but Gram-positive Staphylococcus aureus. In vivo and in vitro experiments showed deoxyribonucleic acid (DNA) synthesis was specifically inhibited by this drug in E. coli.

4-Quinolones↗
PubMed1989

[Percutaneous transluminal coronary angioplasty for treatment of acute myocardial infarction: comparison with percutaneous transluminal coronary recanalization].

Percutaneous transluminal coronary angioplasty (PTCA) was evaluated as a means of reperfusion of the infarct-related coronary artery, and the results were compared with those of percutaneous transluminal coronary recanalization (PTCR). There were no difference in sex, age, infarct location and time from the onset to start of treatment between 135 patients with evolving acute myocardial infarction treated with PTCA (PTCA group) and 113 patients treated with PTCR alone (PTCR group). Fifty-nine patients in the PTCA group underwent PTCA following PTCR; the remaining 76 patients were without prior PTCR. Successful PTCA, defined as a 20% or more reduction in percent luminal stenosis diameter, was achieved in 123 (90%) of the 135 patients in the PTCA group. The reperfusion rate was 93% in the PTCA group and 77% in the PTCR group (p less than 0.01). Residual stenosis immediately after the treatment was 30 +/- 13% in the PTCA group and 70 +/- 16% in the PTCR group (p less than 0.01). In the PTCA group, three cases developed serious complications which were associated with angioplasty: coronary perforation, side branch occlusion resulting in cardiogenic shock and exacerbation of cardiogenic shock. The latter two patients died, however, there was no difference in hospital mortality rate: 6% in the PTCA group versus 11% in the PTCR group. At follow-up angiography performed four weeks after admission, reocclusion of the successfully recanalized arteries was observed in 3% of the PTCA group and in 14% of the PTCR group (p less than 0.01). Regional wall motion was evaluated by left ventriculography using a wall motion score system which consisted of six grades; from normal counted as 0, to dyskinesis counted as 5. There was no difference in the wall motion score between the successful PTCA group and the successful PTCR group (2.6 +/- 1.4 versus 2.8 +/- 1.4), but the scores of both groups were better than those of the non-recanalized group (3.4 +/- 1.0: p less than 0.01). In conclusion, PTCA and PTCR have the same effect on hospital mortality rate and regional wall motion, but PTCA has a higher reperfusion rate and a lower reocclusion rate than does PTCR. Although PTCA has a potential disadvantage inducing serious complications, it appears to be a useful treatment for acute myocardial infarction.

Aged↗
PubMed1989

[Coronary arteriographic findings in the patients with atrial septal defect and pulmonary hypertension (ASD + PH)--compression of left main coronary artery by pulmonary trunk].

The characteristic narrowing of left main coronary artery (LMCA) was found in 44% of patients (pts) with atrial septal defect and pulmonary hypertension (ASD + PH). The cause of the narrowing is thought to be the compression by pulmonary trunk (PT). Cardiac catheterization and coronary arteriography (CAG) were performed in 38 pts with ASD ranging in age from 15 to 62 years. We defined abnormal narrowing as 50% or more stenosis of AHA classification. Sixteen pts (42%) had PH, and of these pts 7 show the abnormal narrowing of LMCA. (18% of all pts with ASD, 44% of pts with ASD + PH). They had no signs of syphilis or aortitis. Of the pts with PH, those with abnormal LMCA revealed higher pulmonary artery mean pressure than those with normal LMCA (43.6 +/- 17.3 and 27.1 +/- 5.5 mmHg respectively. p less than 0.01). Other parts of coronary arteries are intact in all pts. These findings suggest that the LMCA abnormality relates to PH. In all cases with LMCA abnormality the narrowing revealed some special features indicate the cause of narrowing is compression. First, the most severe part of narrowing was the coronary ostium, and severity reduced gradually as distal LMCA. Second, the narrowing was estimated most severely in the view of LAO 20, but almost normal in the view of RAO 30. This finding suggests the narrowing is ellipsoid. Third, the shape of LMCA changed in the different phase of cardiac cycle. In the systole, the cranial border of LMCA was convex, but in the diastole it was concave. This indicates LMCA was soft and compressed.(ABSTRACT TRUNCATED AT 250 WORDS)

Angina Pectoris↗
PubMed1988

Tertiary structure of Bacillus thermoproteolyticus [4Fe-4S] ferredoxin. Evolutionary implications for bacterial ferredoxins.

The structure of a low-potential [4Fe-4S] ferredoxin from Bacillus thermoproteolyticus has been solved using anomalous scattering data from iron atoms in the diffraction data of native crystals and refined partially to a crystallographic R-factor of 0.33, with 2.3 A (1 A = 0.1 nm) resolution data. The least-squares refinement based on the Bijvoet differences has determined that the four iron atoms in the cluster are an equal distance, approximately 2.8 A, apart. The NH ... S hydrogen bonds between polypeptide nitrogen atoms, and both cysteine and inorganic sulfur atoms, are present, as in ferrodoxin from Peptococcus aerogenes. The polypeptide chain of the B. thermoproteolyticus ferredoxin has a fold closely similar to that of 2[4Fe-4S] ferredoxin from P. aerogenes. The structural correspondence indicates strongly that both types of ferredoxin evolved from a common ancestor. The second cluster-binding region in P. aerogenes ferredoxin corresponds to the alpha-helix in B. thermoproteolyticus ferredoxin. The secondary-structure predictions strongly suggest that the alpha-helix is generally present in the monocluster-type ferredoxins. The conformational change to alpha-helix, insertions of a loop and a protrusion, as well as the absence of the second cluster in B. thermoproteolyticus ferredoxin, result in the lack of 2-fold symmetry present in P. aerogenes ferredoxin. So, the track of gene duplication is no longer detectable in the tertiary structure alone. The evolutionary events that may have occurred in the ferredoxins with the [4Fe-4S] cluster are discussed.

Amino Acid Sequence↗
PubMed1988

Identification of the phyto-oestrogen 3',7-dihydroxyisoflavan, an isomer of equol, in human urine and cow's milk.

The isoflavonoid diphenol 3',7-dihydroxyisoflavan, an isomer of the known compound equol (4',7-dihydroxyisoflavan), has been identified in human urine and in cow's milk. The compound was isolated as the glucuronide, purified by column chromatography and identified after hydrolysis to the aglycon. The trimethylsilyl ether derivative was characterized by comparison of its mass spectrum and chromatographic properties with those of synthesized silylated isomers of equol.

Animals↗