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S Nishimura

Publications and source records attributed to S Nishimura.

At least 379 records · Page 21Linked to original sources
PubMed1993

A modified uridine in the first position of the anticodon of a minor species of arginine tRNA, the argU gene product, from Escherichia coli.

The argU (dnaY) gene product, a minor tRNA(Arg), from Escherichia coli has the anticodon N*CU with an unidentified modified nucleoside N* in position 34 [Kiesewetter, S., Fisher, W. & Sprinzl, M. (1987) Nucleic Acids Res. 15, 3184]. In the present study, argU tRNA was purified from E. coli A19 strain and nucleoside N* was characterized by the TLC and HPLC analyses. Nucleoside N* was found to be different from any naturally occurring modified nucleosides. From unfractionated E. coli tRNA species, nucleoside N* was prepared in an amount sufficient for 1H-NMR experiments. By the analyses of one-dimensional and two-dimensional NMR spectra, nucleoside N* was suggested to be 5-methylaminomethyluridine (mnm5U), which was confirmed by comparison with a chemically synthesized preparation of mnm5U. Thus, the occurrence of mnm5U in mature tRNA was found for the first time. Further, the modification of U(34) to mnm5U in this tRNA was found to contribute to the strict recognition of two degenerate codons terminating in A and G.

Anticodon↗
PubMed1993

Requirement of the calcium channel beta subunit for functional conformation.

The cardiac dihydropyridine-sensitive L-type calcium channel was stably expressed in Chinese hamster ovary cells by transfecting the rabbit cardiac calcium channel alpha 1 subunit cDNA with or without coexpression of the beta subunit of skeletal muscle calcium channel. Whereas coexpression of the beta subunit significantly increased DHP binding activity and calcium channel activity, it did not affect the amount of the alpha 1 subunit expressed, as judged by RNA blot hybridization analysis and immunoblotting analysis. The results suggest that association with the beta subunit is necessary for the alpha 1 subunit protein to take a proper conformation suitable for a functional calcium channel.

Animals↗
PubMed1993

A brain-specific transcript from the 3'-terminal region of the skeletal muscle ryanodine receptor gene.

We have shown previously that the skeletal muscle ryanodine receptor mRNA of approximately 16,000 nucleotides codes 5,037 amino acid residues constituting the calcium release channel in skeletal muscle. In this study, RNA blot hybridization analysis shows that the brain contains an RNA species with an estimated size of approximately 2,400 nucleotides hybridizable with the 3'-terminal region of the skeletal muscle ryanodine receptor cDNA. cDNA cloning and genome analysis indicated that two transcripts differing in their start sites are produced from the skeletal muscle ryanodine receptor gene in a tissue-specific fashion, and that the mRNA in brain may code the carboxyl-terminal region of the ryanodine receptor molecule. cDNA expression experiments suggested that the ATG triplet encoding Met4382 of the skeletal muscle ryanodine receptor can function as a translation initiation codon, and that the expressed protein composed of the carboxy terminal 656 amino acid residues of the receptor is located on the endoplasmic reticulum membrane.

Amino Acid Sequence↗
PubMed1993

Double-negative (CD4- CD8-) T cells from adult T-cell leukemia patients also have poor expression of the T-cell receptor alpha beta/CD3 complex.

We present four patients with adult T-cell leukemia (ATL) derived from a novel T-cell subset (CD4-, CD8- [double-negative, DN], T-cell receptor [TCR] alpha beta+). In the ATL cells of these patients, neither gene nor surface expression of CD4 and CD8 antigens was detected. Clinical and laboratory data showed no difference between DN-ATL and CD4+ATL patients. In contrast to typical CD4+ATL cells, DN-ATL cells were shown to express the protein and messenger RNA (mRNA) for S100 beta in immunocytochemical assay and the reverse-transcription polymerase chain reaction assay. The mean fluorescence intensity of the TCR/CD3 complex was extremely low in all four DN-ATL patients as well as in typical CD4+ ATL. All four patients had TCR beta and gamma chain gene rearrangements, with deletion of TCR delta chain gene and mRNA expression for TCR alpha, beta, and CD3 delta but not for TCR gamma and delta chain genes. Thus, CD4- CD8- TCR alpha beta T cells are also a target for human T-cell lymphotrophic virus type I-induced leukemogenesis. In addition, expression of the TCR alpha beta/CD3 complex on the DN-ATL cells was further diminished by the addition of anti-CD3 or anti-TCR alpha beta monoclonal antibody. These results suggest that the decreased expression of the TCR alpha beta/CD3 complex by ATL cells plays a key role in the development of ATL, irrespective of CD4 expression.

Adult↗
PubMed1993

Plasma and urinary heart-type cytoplasmic fatty acid-binding protein in coronary occlusion and reperfusion induced myocardial injury model.

The leakage of heart-type cytoplasmic fatty acid-binding protein (H-FABPc) from injured myocardial cells has been reported. We have previously proposed that its plasma and urinary levels could be used as an early indicator of myocardial injury and also reflect the severity of myocardial injury. To confirm this hypothesis, the time course of changes of the plasma and urinary H-FABPc was investigated during myocardial injury induced by coronary artery occlusion and reperfusion in dogs. The plasma elimination kinetics and urinary excretion kinetics of H-FABPc were also analysed in dogs which were given a bolus injection of exogenous H-FABPc. The distribution of circulating H-FABPc was determined in mice by whole-body autoradiography using 125I-labelled H-FABPc. In myocardial injury model, plasma and urinary H-FABPc level showed rapid increase after reperfusion. The elimination kinetic study revealed that H-FABPc was mono-exponentially cleared from the circulation. The elimination rate constant (Ke) was 0.0275 +/- 0.0094/min (mean +/- S.D., n = 7) and the disappearance half-time (t1/2) was 27.5 +/- 8.4 min (mean +/- S.D., n = 7). Exogenous H-FABPc appeared in urine soon after administration, with the peak level being at 6.9 +/- 2.0 min (mean +/- S.D., n = 7). Whole-body autoradiography also demonstrated that 125I-H-FABPc accumulated rapidly in the kidneys. This study demonstrated that H-FABPc leaked rapidly from injured myocardium and rapidly appeared in plasma and urine. Infarct size was closely correlated with the calculated H-FABPc release (r = 0.89, r2 = 0.80, P < 0.01, n = 7) and with the amount of the urinary H-FABPc (r = 0.94, r2 = 0.88, P < 0.01, n = 7). These data suggest that measurement of the H-FABPc levels in plasma and urine might be useful for the early detection of myocardial injury and also for the assessment of infarct size.

Animals↗
PubMed1993

Sequence-specific 1H and 15N resonance assignments and secondary structure of GDP-bound human c-Ha-Ras protein in solution.

All the backbone 1H and 15N magnetic resonances (except for Pro residues) of the GDP-bound form of a truncated human c-Ha-ras proto-oncogene product (171 amino acid residues, the Ras protein) were assigned by 15N-edited two-dimensional NMR experiments on selectively 15N-labeled Ras proteins in combination with three-dimensional NMR experiments on the uniformly 15N-labeled protein. The sequence-specific assignments were made on the basis of the nuclear Overhauser effect (NOE) connectivities of amide protons with preceding amide and/or C alpha protons. In addition to sequential NOEs, vicinal spin coupling constants for amide protons and C alpha protons and deuterium exchange rates of amide protons were used to characterize the secondary structure of the GDP-bound Ras protein; six beta stands and five helices were identified and the topology of these elements was determined. The secondary structure of the Ras protein in solution was mainly consistent with that in crystal as determined by X-ray analyses. The deuterium exchange rates of amide protons were examined to elucidate the dynamic properties of the secondary structure elements of the Ras protein in solution. In solution, the beta-sheet structure in the Ras protein is rigid, while the second helix (A66-R73) is much more flexible, and the first and fifth helices (S17-124 and V152-L171) are more rigid than other helices. Secondary structure elements at or near the ends of the effector-region loop were found to be much more flexible in solution than in the crystalline state.

Amino Acid Sequence↗
PubMed1993

Alterations in pain threshold and psychomotor response associated with subanaesthetic concentrations of inhalation anaesthetics in humans.

We studied the effects of six inhalation anaesthetics at subanaesthetic concentrations of 0.2 MAC on pain threshold and psychomotor function in six healthy volunteers. When compared with 100% oxygen inhalation, nitrous oxide and methyoxyflurane significantly increased pain threshold as measured by a radiant heat algometer, and prolonged the response time to auditory stimuli. In contrast, halothane, enflurane, isoflurane and sevoflurane produced prolongation of the response time to auditory stimuli but did not influence pain perception. The pain threshold with nitrous oxide remained significantly increased 30 min after its discontinuation, while the response time returned to the preinhalation value. We conclude that nitrous oxide and methoxyflurane possess both analgesic and hypnotic actions but halothane, enflurane, isoflurane and sevoflurane do not have an analgesic action at subanaesthetic concentrations, and the analgesic action of nitrous oxide persists after its elimination.

Adult↗
PubMed1993

Sex-dependent expression of class pi glutathione S-transferase during chemical hepatocarcinogenesis in B6C3F1 mice.

Expression of class pi glutathione S-transferase (GST-II) was investigated during chemical hepatocarcinogenesis in female and male mice. Diethylnitrosamine (DEN; 10 mg/kg body wt) was administered to B6C3F1 mice on day 15 after birth, and liver sections were immunohistochemically stained with GST-II antibody at 12 and 24 weeks thereafter. In the normal mouse liver, GST-II was strongly expressed in males but only weakly in females. At 24 weeks after DEN treatment, the majority of preneoplastic foci could be detected as GST-II-positive in the female mice, while those in males were observed as to have decreased GST-II relative to the background. Class alpha GST-I and class mu GST-III did not exhibit any remarkable changes in preneoplastic foci. This result indicates that GST-II is a useful positive and negative marker for preneoplastic lesions in female and male mouse livers. In addition, class pi GST-II may be useful for the rapid screening hepatocarcinogens in mice because GST-II-positive or -negative single cells and minifoci, considered as precursor initiated populations, were detectable in females and males at 12 weeks after the DEN injection.

Animals↗
PubMed1993

Role of oxygen radicals in indomethacin-induced gastric mucosal microvascular injury in rats.

To investigate the pathogenesis of indomethacin-induced gastric mucosal injury, vascular injury was examined in the rat using Evans blue and monastral blue vascular tracers. Extravasation of intravenously injected Evans blue into the gastric mucosa was used as an indicator of vascular permeability. Monastral blue was used to demonstrate vascular injury morphologically. The extravasated content of Evans blue significantly increased and reached the maximum at 2 h after indomethacin administration. The increase in Evans blue content was significantly inhibited by the pretreatment with superoxide dismutase (SOD) and SOD + catalase, but not with catalase alone. Monastral blue-labeled damaged endothelial cells in the gastric mucosa also increased at 2 h after indomethacin administration, which increase was reduced by pretreatment with SOD and SOD + catalase. These results indicate that oxygen radicals, including the superoxide radical, play an important role in the microvascular injury induced by indomethacin, which in turn plays a primary role in the development of gross hemorrhagic erosions.

Animals↗
PubMed1993

Elevated level of 8-hydroxydeoxyguanosine in DNA of liver, kidneys, and brain of Long-Evans Cinnamon rats.

Long-Evans Cinnamon (LEC) rats, a mutant strain originating from Long-Evans rats, spontaneously develop hereditary hepatitis followed by hepatocellular carcinoma. The hepatic disorder in LEC rats is associated with their abnormal copper metabolism; metal-catalyzed reactions often give rise to oxygen radicals, which may be related to the carcinogenesis. By means of high-pressure liquid chromatography with electrochemical detection, cellular DNA damage caused by oxygen radicals can be assessed in terms of the amount of 8-hydroxydeoxyguanosine (oh8dG). We assayed the amount of oh8dG in DNA of liver, kidneys, and brain of LEC and Long-Evans Agouti (LEA) control rats in seven groups (n = 3 to 6) aged from 5 weeks to 24 months. Control rats, a healthy sibling line, were age-matched. The amount of oh8dG was correlated with the severity of the age-related clinical symptoms in LEC rats. The amount was higher in LEC rats than in the controls, especially in the liver at the acute stage of hepatitis. These findings suggest that oxygen radicals may be important in the carcinogenesis that occurs in LEC rats.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed1993

Defective calcium-dependent signal transduction in T lymphocytes of ataxia-telangiectasia.

T-cell functions of two patients with ataxia-telangiectasia were investigated. Patients with ataxia-telangiectasia had reduced percentages of circulating CD3+ cells and CD4+ cells, although neither patient had a reduced percentage of circulating CD8+ cells. The proliferative responses and interleukin-2 production of peripheral blood mononuclear cells to T-cell mitogens were reduced in the patients. The intracellular calcium concentration in T cells or CD4+ cells from both patients was only slightly increased after phytohaemagglutinin stimulation. Moreover, the concentration after OKT3 stimulation was not or only slightly increased in T cells or CD4+ cells from both patients. Our results suggest that the functional defect of T cells is caused by defective Ca(2+)-dependent signal transduction through the CD3 complex of the surface in T cells of ataxia-telangiectasia.

Adolescent↗
PubMed1993

Three-dimensional structure of human insulin-like growth factor-I (IGF-I) determined by 1H-NMR and distance geometry.

The three-dimensional structure of human insulin-like growth factor-I has been determined through a combination of NMR measurements and distance geometry calculations. A total of 320 interatomic distance constraints, including 12 related to the disulfide bridges, were used in these calculations. The resulting structure is characterized by the presence of three helical rods corresponding to the sequence regions, Ala8-Cys18, Gly42-Cys48 and Leu54-Cys61. Furthermore, a turn structure and an extended structure exist in the Gly19-Gly22 and Phe23-Asn26 regions, respectively. Neglecting the N- and C-termini, with their expectedly high degree of mobility as well as a fluctuating C-domain, the r.m.s.d. value is 1.9 A for backbone atoms. Those of the three alpha-helical regions are 1.0, 0.9 and 0.8 A, respectively, 1.8 A being that for the total backbone atoms participating in the formation of these three helices, showing the good convergence of their spatial arrangements. The overall structure obtained here shows that the human IGF-I molecule folds into a spatial structure very similar to that of insulin in an aqueous solution.

Amides↗
PubMed1993

[Seroepidemiological study of human rotavirus in northern part of Tokyo from 1990 to 1992 by using reverse transcription-polymerase chain reaction].

A seroepidemiological study of rotavirus was conducted in the northern part of Tokyo from 1990 to 1992 by using reverse transcription-polymerase chain reaction (RT-PCR). G1 and G3 types were detected in the winter between 1990 and 1991, however G1 type was appeared mainly in the winter between 1991 and 1992. G3 type was observed as the main type during the winter in the 10 year survey in the Tokyo area for the first time. RT-PCR was useful in the seroepidemiological studies of rotavirus infection.

Base Sequence↗
PubMed1993

Nuclear Ribosomal DNA as a Probe for Genetic Variability in the Japanese Pear Pathotype of Alternaria alternata.

A restriction fragment length polymorphism analysis of nuclear ribosomal RNA genes (rDNA) was used to measure the amount and distribution of genetic variability in populations of the Japanese pear pathotype of Alternaria alternata on both micro- and macrogeographical scales. A total of 322 isolates were obtained from 13 areas in Aichi, Gifu, and Tottori Prefectures in central and western Japan. The restriction fragment length polymorphism analysis revealed that the pathogen populations contained at least eight rDNA variants. The eight variant types differed in the lengths and in the presence of the restriction sites in spacer DNA outside the coding regions for rRNAs. A total of 271 isolates were classified into the eight types. The remaining 51 isolates were determined to have mixed rDNA types. Single pear fields typically contained two to five types of rDNA variants. The frequencies of rDNA variants in 11 populations in Tottori Prefecture were compared; in this prefecture orchards containing the susceptible pear are common. Except for one collection site, there were no significant differences in the composition of the rDNA variants among the populations. This suggests that dispersal of inocula has occurred frequently in Tottori Prefecture. In contrast, significantly different distributions were observed in the three prefectures, indicating that gene flow between prefectures might be limited by geographical isolation. DNA fingerprints resulting from hybridization with a moderately repetitive DNA sequence of the fungus revealed greater genetic variability and geographical differences in genetic population structure even within the same rDNA type.

Journal Article↗
PubMed1993

Ph+ acute myelogenous leukemia with t(7;11)(p15;p15) and clonal evolution in relapse after bone marrow transplantation.

A 20-year-old female with Ph+ acute myelogenous leukemia (M2) associated with t(7;11)(p15;p15) is reported. Bone marrow aspirates were hypercellular with leukemic cells including Auer rods. Chromosome analysis showed t(7;11) and the Ph chromosome. After complete remission, normal karyotype was restored. Normal male karyotypic cells replaced the bone marrow following allogeneic bone marrow transplantation from her brother. On day 358, cytogenetic study at relapse revealed 14q+ as an additional change and clearly showed that the abnormal clone was derived from the patient, because metaphases with XX were all of abnormal karyotype and those with XY were normal.

Adult↗
PubMed1993

Quantitative adenosine 201Tl single-photon emission computed tomography for the early assessment of patients surviving acute myocardial infarction.

BACKGROUND: We prospectively investigated whether adenosine 201Tl tomography (SPECT) could determine the extent of coronary artery disease, the presence of jeopardized myocardium, and the risk for in-hospital cardiac events in 120 clinically stable patients early (5 +/- 3 days) after myocardial infarction. METHODS AND RESULTS: All patients had coronary angiography and SPECT in close proximity. Adenosine SPECT identified 99% of infarct-related arteries and 82% of severely stenosed (> or = 70%) noninfarct arteries. Multivessel disease was accurately predicted in 69% of patients. Sixty-five percent of stenosed noninfarct arteries had matching thallium perfusion defects, and 92% of these were reversible. The specificity of adenosine SPECT was > 90%. Thallium redistribution occurred often within infarct (59%) and noninfarct (92%) zones. The patency status of the arteries, however, did not predict the presence or extent of jeopardized myocardium. The perfusion defect size was larger (p = 0.0001) in patients with (45 +/- 18%) than in those without (22 +/- 15%) in-hospital cardiac events. Furthermore, 90% of patients with events had a > or = 20% perfusion defect compared with only 38% of those without events (p = 0.0001). The positive-predictive accuracy for developing a cardiac event was 70% when the perfusion defect size was > 30%. The ischemic defect also was larger in patients with (19 +/- 14%) than in those without (10 +/- 10%) events (p = 0.001). The positive- and negative-predictive values for developing early postinfarction angina were 43% and 91%, respectively, when the ischemic defect was > 12%. CONCLUSIONS: In selected low-risk survivors of myocardial infarction, early quantitative adenosine SPECT is safe and accurate in detecting and localizing coronary stenoses, assessing the extent of jeopardized myocardium, and determining subsequent risk for in-hospital cardiac events.

Adenosine↗
PubMed1993

Angiographic and hemodynamic determinants of myocardial ischemia during adenosine thallium-201 scintigraphy in coronary artery disease.

BACKGROUND: Myocardial ischemia attributed to coronary steal may occur in some patients receiving pharmacological coronary vasodilation. ECG ST-segment depression is a marker of myocardial ischemia in these patients, but the factors determining the presence or absence of ischemia are not well known. METHODS AND RESULTS: To examine the angiographic, hemodynamic, and scintigraphic determinants of adenosine-induced ischemic ST-segment depression in patients with coronary artery disease, we studied 65 consecutive patients (45 men and 20 women; mean age, 65 +/- 12 years) who showed reversible perfusion defects during adenosine (140 micrograms.kg-1.min-1 for 6 minutes) 201Tl single-photon emission computed tomography. Patients with prior myocardial infarction were excluded. Ischemic ST depression occurred in one third of the whole cohort (22 of 65 patients). The presence of coronary collateral vessels (p = 0.001), systolic blood pressure at baseline (p = 0.006), and adenosine-induced anginal chest pain (p = 0.011) were the only significant independent predictors of ischemic ST-segment depression by stepwise logistic regression analysis. Rate-pressure product at baseline, systolic blood pressure, heart rate, rate-pressure product, increase in heart rate, and rate-pressure product during adenosine infusion and maximal percent stenosis were variables also significantly related to ischemic ST depression by univariate analysis but were not predictive after the three primary variables were included in the regression model. Perfusion defect size, number of diseased vessels, and age did not correlate with ST-segment depression. CONCLUSIONS: The presence of collaterals, which may predispose to coronary collateral steal, is the most significant correlate of ischemic ST-segment depression during adenosine infusion. Systolic blood pressure at baseline, which may affect the myocardial oxygen supply/demand ratio and anginal chest pain induced by adenosine, are additional variables related to ischemic ST-segment depression during adenosine infusion.

Adenosine↗