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T Sugimoto

Publications and source records attributed to T Sugimoto.

At least 19 recordsLinked to original sources
PubMed1992

Molecular cloning and characterization of the platelet-activating factor receptor gene expressed in the human heart.

PAF decreases cardiac contractility and blood pressure. To characterize the cardiac PAF receptor, we screened a human ventricular cDNA library in a low stringency condition, using a PCR product derived from guinea pig lung PAF receptor as a probe. Four clones were obtained and named HV1-4. In Xenopus oocytes injected with cRNA derived from HV3 or 4 but not from HV1 or 2, PAF elicited a Ca(2+)-activated Cl- current. HV3 and HV4 were duplicate clones, encoding a 342 amino-acid polypeptide which was identical to that of the human leukocyte PAF receptor. However, a portion of the 5' untranslated region of HV3 (or 4) was different from that of the leukocyte receptor cDNA. Northern blotting of human ventricles and atria using the HV3 insert showed a single band of approximately 4 kb. These results suggest a tissue-specific translational mechanism responsible for regulation of the expression of the PAF receptor mRNA in these tissues.

Amino Acid Sequence↗
PubMed1992

Calretinin-immunoreactivity in the oro-facial and pharyngeal regions of the rat.

Calretinin-immunoreactivity (CR-ir) was examined in the rat oro-facial and pharyngeal tissues using an immunofluorescence method. CR-ir was distributed in the entire size range of trigeminal ganglion neurons. CR-ir was also observed in nerve fibers surrounding neuronal cell bodies in autonomic ganglia, and in nerve endings in the lip, tongue, incisal papilla, soft palate, pharynx and epiglottis. CR-immunoreactive nerve endings were all in close proximity to the epithelium, and classified into 2 types; simple (free nerve ending) and taste-bud-related types. In the salivary gland, positive nerve fibers were seen around large excretory ducts. The present study indicates that viscerosensory (probably including gustatory) nerve fibers innervating the oral and pharyngeal tissues contain CR, while somotosensory nerve fibers innervating the facial skin are devoid of CR.

Animals↗
PubMed1992

Autocrine and paracrine effects of endothelium-derived relaxing factor on intracellular Ca2+ of endothelial cells and vascular smooth muscle cells. Identification by two-dimensional image analysis in coculture.

To elucidate the effects of endothelium-derived relaxing factor (EDRF) released from vascular endothelial cells (ECs) on handling of intracellular calcium ion (Ca2+i) in ECs themselves and vascular smooth muscle cells (VSMCs), we measured the Ca2+i by two-dimensional digital image analysis of fura-2-loaded ECs and VSMCs in tissue culture. In isoculture of one cell type, adenosine triphosphate (ATP, 1 microM) transiently increased the Ca2+i of both ECs and VSMCs. High-K+ depolarization or angiotensin II also elevated the Ca2+i of VSMCs, whereas neither stimulants changed the Ca2+i of ECs. In coculture of ECs with VSMCs, the same dose of ATP rapidly increased the Ca2+i of ECs and then transiently decreased the Ca2+i of VSMCs to below the resting level. The maximal Ca2+i-modulating effects of ATP on both cell types were reproducible after the second application of ATP. Three kinds of EDRF blockers (L-NG-monomethylarginine, methemoglobin, or methylene blue) potentiated the ATP-induced Ca2+i rise in ECs and attenuated the Ca2+i reduction in VSMCs, suggesting the autocrine and paracrine effects of EDRF on ECs and VSMCs, respectively. However, neither indomethacin, superoxide dismutase, nor neutralizing monoclonal antibody to endothelin-1 altered the second responses. Thus, two-dimensional Ca2+i image analysis of ECs and VSMCs in coculture enabled direct visualization of the EDRF actions in ECs and VSMCs and their modifications.

Adenosine Triphosphate↗
PubMed1992

Endothelin 1 hydrolysis by rat kidney membranes.

Hydrolysis of endothelin 1 by rat kidney membranes was investigated using a reverse-phase HPLC and an automated gas-phase protein sequencer. Endothelin 1 was hydrolyzed into four major fragments which were detected by HPLC. Phosphoramidon, an inhibitor of neutral endopeptidase 24,11, almost completely suppressed the production of three fragments, but one fragment was not affected by the inhibitor. Analysis of N-terminal sequences of the degradation products revealed that the phosphoramidon-sensitive fragments were generated by cleavage at the Ser5-Leu6 bond of endothelin 1 that was identical with its cleavage site by purified rat endopeptidase 24,11, reported previously. The phosphoramidon-insensitive fragment was produced by cleavage at Leu17-Asp18, which was distinct from the sites by endopeptidase 24,11, but corresponded to that by a phosphoramidon-insensitive metallo-endopeptidase recently isolated from rat kidney membranes by us [(1992) Eur. J. Biochem. 204, 547-552]. Kinetic determination of endothelin 1 hydrolysis by the isolated enzyme yielded values of Km = 71.5 microM and kcat = 1.49 s-1, giving a ratio of kcat/Km = 2.08 x 10(4) s-1.M-1. The Km value was much higher and the kcat/Km value was much lower than those for rat endopeptidase 24,11 reported previously. Thus, endopeptidase 24,11 appears to hydrolyze endothelin 1 more efficiently than the isolated enzyme does. Both enzymes may play physiological roles in the metabolism of endothelin 1 by rat kidney membranes in vivo.

Amino Acid Sequence↗
PubMed1992

Salvage of infarcted myocardium by angiogenic action of basic fibroblast growth factor.

Coronary collateral vessels reduce damage to ischemic myocardium after coronary obstruction. Factors that stimulate collateral formation are expected to have ameliorating effects on myocardial infarction. In a canine experimental myocardial infarct model, intracoronary injection of basic fibroblast growth factor (bFGF) improved cardiac systolic function and reduced infarct size. Treatment with bFGF increased the number of arterioles and capillaries in the infarct. Thus, the angiogenic action of bFGF might lead to a reduction in infarct size. The application of bFGF might bring about a therapeutic modality for the salvage of infarcted myocardium.

Animals↗
PubMed1992

Mapping of the cochlear nucleus subregions in the rat with neuronal Fos protein induced by acoustic stimulation with low tones.

To explore the mode of appearance of Fos, a gene product of proto-oncogene c-fos, in the cochlear nucleus, a pure tone was given to rats and Fos was detected by immunohistochemistry. Following low-tone stimuli applied with moderate ranges of sound intensity, neurons with Fos-label occurred band-like in the ventral subregions of the dorsal cochlear nucleus. Organization of low-to-high tones in the ventral-to-dorsal orientation became visible at the caudal level. Several other subnuclei consistently exhibited Fos with no topographic pattern. Neurons interspersed in the adjoining vestibulocochlear nerve were also found to elicit Fos. Low-tone stimuli with very high sound intensity led to a rather widespread distribution of Fos, making the tone-specific distribution less visible.

Acoustic Stimulation↗
PubMed1992

Role of cellular superoxide dismutase against reactive oxygen metabolite injury in cultured bovine aortic endothelial cells.

We examined the protective effect of cellular superoxide dismutase against extracellular hydrogen peroxide in cultured bovine aortic endothelial cells. 51Cr-labeled cells were exposed to hydrogen peroxide generated by glucose oxidase/glucose. Glucose oxidase caused a dose-dependent increase of 51Cr release. Pretreatment with diethyldithiocarbamate enhanced injury induced by glucose oxidase, corresponding with the degree of inhibition of endogenous superoxide dismutase activity. Inhibition of cellular superoxide dismutase by diethyldithiocarbamate was not associated either with alteration of other antioxidant defenses or with potentiation of nonoxidant injury. Enhanced glucose oxidase damage by diethyldithiocarbamate was prevented by chelating cellular iron. Inhibition of cellular xanthine oxidase neither prevented lysis by hydrogen peroxide nor diminished enhanced susceptibility by diethyldithiocarbamate. These results suggest that, in cultured endothelial cells: 1) cellular superoxide is involved in mediating hydrogen peroxide-induced damage; 2) superoxide, which would be generated upon exposure to excess hydrogen peroxide independently of cellular xanthine oxidase, promotes the Haber-Weiss reaction by initiating reduction of stored iron (Fe3+) to Fe2+; 3) cellular iron catalyzes the production of a more toxic species from these two oxygen metabolites; 4) cellular superoxide dismutase plays a critical role in preventing hydrogen peroxide damage by scavenging superoxide and consequently by inhibiting the generation of the toxic species.

Allopurinol↗
PubMed1992

The direct involvement of cAMP-dependent protein kinase in the regulation of collagen synthesis by parathyroid hormone (PTH) and PTH-related peptide in osteoblast-like osteosarcoma cells (UMR-106).

The present study was performed to characterize the direct involvement of cAMP-dependent protein kinase (PKA) in the regulation of collagen synthesis by parathyroid hormone (PTH) and PTH-related peptide (PTHrP) in osteoblastic osteosarcoma cells, UMR-106. Sp-cAMPS (10(-4)M), a direct activator of PKA, as well as dibutyryl cAMP (dbcAMP, 10(-4)M) significantly inhibited collagen synthesis. Human (h) PTH-(1-34) (10(-7)M) and hPTHrP (10(-7) M) inhibited collagen synthesis to the same degree. Although Rp-cAMPS, which acted directly as an antagonist in the activation of PKA, did not affect collagen synthesis by itself, it significantly antagonized dbcAMP- and Sp-cAMPS-induced inhibition of collagen synthesis. Moreover, Rp-cAMPS antagonized PTH- and PTHrP-induced inhibition of collagen synthesis to the same degree. The present study first indicated that the activation of PKA was directly linked to the regulation of collagen synthesis by PTH in osteoblast and that PTHrP had the same effect on collagen synthesis presumably through the same mechanism as PTH.

Animals↗
PubMed1992

Differential expression of myogenic regulatory genes, MyoD1 and myogenin, in human rhabdomyosarcoma sublines.

A cell line (SCMC-MM-1) was established from a human abdominal tumor that was initially diagnosed as a malignant mesenchymoma by histological, immunohistochemical and clinical criteria. The cell line was composed of 2 morphologically and immunohistochemically distinct cell types, one with a small polygonal phenotype (P-type), characterized by the immunostaining of vimentin and the presence of a few electron-microscopically visible organelles, and the other with a giant tubular phenotype (T-type), characterized by the immunostaining of desmin, alpha-sarcomeric actin and skeletal-muscle myosin, and the presence of thick and thin myofilaments and Z-line materials. The parental cell line was cloned into 2 sublines, a P-type clone (SCMC-MM-1-19P) and a T-type clone (SCMC-MM-1-1T), which shared both 2q37 and 11p15 translocations, the characteristic chromosomal aberrations for rhabdomyosarcoma, with the parental SCMC-MM-1 cell line. Northern-blot analyses of the myogenic regulatory genes, including MyoD1 and myogenin, demonstrated the expression of MyoD1 in both of these sublines. Myogenin was very weakly expressed in the SCMC-MM-1-19P subline, but strongly expressed in the SCMC-MM-1-1T subline. Chromosomal and myogenic-regulatory-gene analyses revealed that both of these sublines were rhabdomyosarcoma cell lines. Furthermore, the regulatory-gene analyses indicated that these 2 sublines represented 2 distinct differentiation stages of myoblasts, and that MyoD1 and myogenin could serve as the lineage marker and the differentiation marker, respectively, of human rhabdomyosarcoma.

Blotting, Northern↗
PubMed1992

Characterization of atrial natriuretic peptide in urine from rats treated with a neutral endopeptidase inhibitor.

To explore the mechanisms for the natriuretic effects of a neutral endopeptidase inhibitor, candoxatril, the concentration of atrial natriuretic peptide (ANP) and its molecular forms in the urine of Dahl salt-sensitive (S) rats were examined. Candoxatril-induced natriuresis (+120%, p less than 0.05) was associated with a marked increase in the urinary ANP excretion (+1200%, p less than 0.05). Analysis by Sephadex G-50 gel filtration revealed that molecular weight of the major fraction of immunoreactive (ir-) ANP in the plasma of candoxatril-treated Dahl S rats was 3K, whereas that in the urine was 2.5 K. Further analysis by reverse phase high performance liquid chromatography showed that ir-ANP in the plasma of Dahl S rats was alpha-rANP (1-28), while that in the urine from rats treated with candoxatril was alpha-rANP (1-25). These results indicate that candoxatril inhibits the complete degradation of ANP in the kidney, thereby increasing the amount of biologically active ANP reaching the distal nephron and contributing to natriuresis.

Analysis of Variance↗
PubMed1992

The activation of cAMP-dependent protein kinase is directly linked to the stimulation of bone resorption by parathyroid hormone.

The present study was performed to characterize the direct involvement of cAMP in the stimulation of bone resorption by parathyroid hormone (PTH), using Sp-cAMPS and Rp-cAMPS, which were the direct agonist and antagonist in the activation of cAMP-dependent protein kinase (PKA), respectively. Bone resorbing activity was estimated as the number of pits formed on the dentine slice and total area of pits per slice in bone marrow cells derived from 2 week-old mice. Dibutyryl cAMP (dbcAMP)(10(-4)M) and Sp-cAMPS (10(-4)M) caused the remarkable stimulation of bone resorption. Although Rp-cAMPS (10(-4)M) did not affect bone resorption by itself, it significantly inhibited dbcAMP- and Sp-cAMPS-induced stimulation of bone resorption. Moreover, Rp-cAMPS (10(-4)M) antagonized 10(-7)M human PTH-(1-34)-induced stimulation of bone resorption, although it did not affect 10(-8)M 1,25(OH)2D3-induced stimulation of bone resorption. Present study indicates the direct involvement of PKA in the stimulation of bone resorption by PTH.

Animals↗
PubMed1992

Constitutive expression of c-fos gene inhibits type 1 collagen synthesis in transfected osteoblasts.

To clarify the contribution of c-fos DNA to bone formation, the effect of constitutive expression of the c-fos gene in collagen synthesis was examined by introducing c-fos DNA into osteoblastic MC3T3-E1 cells. The [3H] proline incorporation into the collagenase digestible protein(CDP) and the percent collagen synthesis were significantly decreased in the c-fos transfectants which constitutively express c-fos mRNA as compared with control transfectants. Transcription of type 1(alpha 1) collagen gene was also specifically decreased in the c-fos transfectants. This indicates that constitutive expression of c-fos DNA interferes with bone formation by inhibiting collagen synthesis in osteoblasts.

Animals↗
PubMed1992

Expression and role of interleukin-2 receptor beta chain on CD4-CD8- T cell receptor alpha beta+ cells [corrected].

Using anti-murine interleukin-2 receptor beta chain (IL-2R beta) monoclonal antibody (mAb), we have examined the expression of IL-2R beta on murine thymocyte subpopulations. We found that it was constitutively expressed on 1%-4% of thymocytes in an almost mutually exclusive fashion with IL-2R alpha. The expression of IL-2R beta is developmentally regulated. While it is expressed mainly on T cell receptor gamma delta+ (TcR gamma delta+) cells during fetal age, the major subpopulation expressing IL-2R beta in adult mouse shifts to CD4-CD8-TcR alpha beta+ thymocytes. A considerable portion of CD4-CD8- TcR alpha beta+ cells in other organs, including spleen, bone marrow and liver, was also found to express IL-2R beta. In fetal thymus organ culture, the above thymocyte subset was induced to expand in response to exogeneous IL-2, and the expansion was inhibited by addition of anti-IL-2R beta mAb, suggesting that IL-2R beta is functional in this subpopulation. However, in vivo blockade of the IL-2/IL-2R pathway with the mAb did not exert any effects on the appearance of CD4-CD8- TcR alpha beta+ cells both in the thymus and the periphery. This indicates that the development of CD4-CD8- TcR alpha beta+ cells is not solely controlled by IL-2 but also by other complex elements.

Animals↗
PubMed1992

Comparison of bone mineral content among Japanese, Koreans, and Taiwanese assessed by dual-photon absorptiometry.

Throughout the world the diagnosis and management of osteoporosis currently involves the measurement of bone mineral content. There are, however, no studies comparing bone mineral content among Asian people. This cross-sectional study was designed to quantify spine and femur bone mineral density (BMD) in Japanese and compare BMD among Asian people (Japanese, Koreans, and Taiwanese) using the same model dual-photon system (Norland Model 2600). Following a peak BMD in the third and fourth decades, the Japanese BMD values of the lumbar spine and femoral neck showed a clear decrease (annual loss of 0.99 and 0.74%, respectively) with age in females. On the other hand, Japanese BMD values were stable in males until the fifth decade. There was some decrease in BMD with age after the fifth decade, which was much less obvious than that in females. An age-dependent loss of BMD was clearly observed in Japanese and Korean but not in Taiwanese females. Korean males seemed to have a clearer age-dependent loss of BMD compared to Japanese males. Our findings indicate that differences may exist in the BMD of Asian people and that in addition to the quantitative determination of individual BMD, dual-photon absorptiometry may be useful for the comparison of BMD among different ethnic and cultural groups.

Absorptiometry, Photon↗