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Biomedical subjects

S Sakamoto

Publications and source records attributed to S Sakamoto.

At least 163 records · Page 9Linked to original sources
PubMed1998

Extra-chromosomal telomere repeat DNA in telomerase-negative immortalized cell lines.

We found novel extra-chromosomal telomere repeat (ECTR) DNAs in telomerase-negative immortalized KMST-6 cells, by staining these cells with a (TTAGGG)n probe using both cycling oligonucleotide-primed in situ synthesis and by fluorescence in situ hybridization. Relatively small amounts of ECTR DNAs were also observed in telomerase-negative VA13 and SUSM-1 cells, but not observed in telomerase-positive immortalized HeLa cells. The ECTR DNAs existed mainly in the nucleoplasm with a small amount in the cytoplasm. The nucleoplasm ECTR DNAs were co-stained with an antibody directed to the telomeric-repeat binding factor 1 (TRF1), suggesting that they exist as a complex with TRF1. In consistent with these cytological studies, Southern blot analysis showed the existence of small telomere repeat DNAs. The ECTR DNA may provide an insight into the elucidation of the mechanisms responsible for the maintenance of telomeres in telomerase-negative immortalized cells.

Cell Line↗
PubMed1998

A lipoprotein lipase activator, NO-1886, improves endothelium-dependent relaxation of rat aorta associated with aging.

Endothelial function is closely related to development of atherosclerosis and is impaired with aging. The novel compound NO-1886, 4-diethoxyphosphorylmethyl-N-(4-bromo-2-cyanophenyl)benzamid e, is a lipoprotein lipase activator and its long term administration protects against the development of experimental atherosclerosis in animals. The aim of this study was to ascertain whether NO-1886 ameliorates the impaired endothelium-dependent relaxation of rat aorta associated with aging. NO-1886 (50 mg/kg p.o.) was administered to 7-month old rats for 3 months. Plasma lipid, glucose and insulin levels in old control rats (10 months of age) were significantly higher than those of young rats (2 months of age). NO- 1886 decreased plasma triglyceride levels (old rats, 233+/-10 mg/dl; old rats + NO-1886, 172+/-16 mg/dl, P < 0.01) and increased plasma high density lipoprotein (HDL) cholesterol level (old rats, 72+/-6 mg/dl; old rats + NO-1886, 142+/-6 mg/dl, P < 0.001) in old rats, but had no effects on plasma glucose or insulin. The endothelium-dependent relaxation of the thoracic aorta caused by histamine was significantly impaired in old rats (% relaxation at 10(-5.5) M histamine: young rats 25.4+/-3.1%; old rats 14.1+/-1.9%, P < 0.01), an effect completely prevented by NO-1886 (old rats + NO-1886; 22.8+/-2.8%, P < 0.05 vs. old rats). In contrast, NO-1886 showed no effect on the endothelium-independent relaxation by sodium nitroprusside. These results indicate that NO-1886 improves impaired endothelium-dependent relaxation of rat aorta associated with aging, possibly by correcting lipid metabolism.

Aging↗
PubMed1998

Nitric oxide activates Ca2+-activated K+ channels in cultured bovine adrenal chromaffin cells.

The effects of sodium nitroprusside (SNP) on Ca2+-dependent K+ (KCa) channels in cultured bovine adrenal chromaffin cells were investigated using single channel recording patch-clamp techniques. KCa channels were activated by application of 100 microM SNP to the extracellular side of cell-attached patches. Methylene blue (300 microM), an inhibitor of soluble guanylate cyclase, or H-8 (1 microM), a protein kinase inhibitor with relative specificity for cGMP-dependent protein kinase, diminished but did not completely abolish the SNP-induced KCa channel activation. Diethylamine/NO complex (DEA/NO), an NO donor, also activated KCa channels in cell-attached patches. Furthermore, application of 100 microM SNP or 100 nM DEA/NO to the intracellular surface of excised inside-out patches also activated KCa channels in the bath solution which contained 1 microM Ca2+. These results indicate that SNP is capable of activating the KCa channel via cGMP-dependent and -independent mechanisms. These studies demonstrate that NO may serve as an important regulatory mechanism for catecholamine secretion in chromaffin cells via the activation of KCa channels.

Adrenal Medulla↗
PubMed1998

Interaction of Oct-1 and automodification domain of poly(ADP-ribose) synthetase.

We isolated several clones from a matchmaker two-hybrid system human lymphocyte cDNA library using an automodification domain of poly(ADP-ribose) synthetase (PARS) as a probe. A DNA sequence (approximately 1 kbp) of the clone was identical to part of the Oct-1 DNA sequence. We then constructed either a His-tagged or GST fusion protein of the inserted cDNA from the clone and the fusion protein was shown to interact with PARS by far-Western blot analysis and co-precipitation with affinity resin. Furthermore, the His-tagged Oct-1/POU-homeo fusion protein interacted weakly with the octamer motif of the DRa promoter and the addition of PARS fusion protein greatly increased the DNA binding activity. These results suggest that PARS interacts with Oct-1 and stabilizes the binding of Oct-1 to the octamer motif.

Base Sequence↗
PubMed1998

Factor structures of the Zung Self-Rating Depression Scale (SDS) for undergraduates.

In order to categorize the items of the Zung Self-Rating Depression Scale (SDS) so as to allow the construction of subscales, the Japanese version of the SDS was administered to a total of 2,258 undergraduates. Principal-component analyses of the SDS extracted three factors interpretable as cognitive, affective, and somatic symptoms. The SDS was then administered to 597 undergraduates in order to cross-validate the factor structures. The coefficient of congruence and the goodness-of-fitness index generated by a confirmatory factor analysis showed good cross-validity of the factor structures.

Adolescent↗
PubMed1998

The preoccupation scale: its development and relationship with depression scales.

Self-focus has been thought to be an important factor in the development and maintenance of depression. The disposition to focus attention inward has been measured by the Private Self-Consciousness Scale (PSCS), which does not reflect the duration of self-focusing. Study 1 aimed to develop a Self-Preoccupation Scale (SPS) that would reflect both the degree and duration of self-focusing. In addition, a new concept, external-preoccupation-the maintenance of external-focus on a specific object-was proposed as a risk factor of depression. An External-Preoccupation Scale (EPS) was developed to measure this. Both the SPS and EPS showed excellent internal consistency and test-retest reliability. Study 2 aimed to examine the relationship between the SPS, EPS, and PSCS and depression. The EPS was not significantly correlated with depression scales. The moderate correlations of the SPS with the depression scales were significantly higher than the correlations of the PSCS with the depression scales.

Adult↗
PubMed1998

Different personalities between depression and anxiety.

We examined the different personality dimensions between depression and anxiety with Cloninger's seven-factor model of temperament and character. The Temperament and Character Inventory (TCI), which measures four temperament and three character dimensions of Cloninger's personality theory (125-item short version), the Self-rating Depression Scale (SDS), and the State-Trait Anxiety Inventory (STAI) were administered to 223 Japanese students. With hierarchical regression analysis, the SDS score was predicted by scores of Harm-Avoidance, Self-Directedness, and Self-Transcendence, even after controlling for the STAI score. The STAI score was predicted by scores of Self-Directedness and Cooperativeness, even after controlling for the SDS score. More importance should be attached to these dimensions of character because they might contribute to both depression and anxiety.

Adolescent↗
PubMed1998

Lactate-induced vascular relaxation in porcine coronary arteries is mediated by Ca2+-activated K+ channels.

Under ischemic conditions and during strenuous exercise, lactate concentrations increase in coronary artery smooth muscle cells. Although lactate causes pH-independent vasorelaxation, the mechanisms responsible for this effect are unclear. We investigated the effect of lactate on K+ channels in smooth muscle cells from porcine coronary arteries. Neutralized lactate (3-100 mm) induced vasorelaxation in ring segments of porcine coronary arteries precontracted with KCl in a dose-dependent manner. One millimolar tetraethylammonium (TEA), an inhibitor of Ca2+-activated K+ channels (KCa channels), reversed the lactate-induced relaxation, while 60 microM glibenclamide, an inhibitor of ATP-sensitive K+ channels (KATP channels), did not. In both inside-out and cell-attached patch clamp technique with cultured smooth muscle cells, the KCa channels were activated by lactate. In inside-out patches, lactate activated KCa channels, even under acidic conditions. This is in contrast to the effect of H+ which inactivated KCa channels. We conclude that vasodilation of porcine coronary arteries induced by lactate is, at least in part, mediated by activation of KCa channels. This effect may be self-protective by maintaining coronary blood flow during ischemia.

Animals↗
PubMed1998

Postocclusive Reactive Hyperemia During Vascular Reconstruction

The purpose of this basic investigation was to clarify the postocclusive reactive hyperemia during vascular reconstruction using laser Doppler flowmetry (LDF). For the fundamental experiment, thirty-nine limbs with arteriosclerosis obliterans (ASO) in Stage II according to Fontaine's classification and 33 limbs without arterial or venous disease were chosen. In the supine position, a thigh cuff was applied to the lower thigh of a subject. Systolic Doppler thigh pressure was obtained and thigh/arm pressure index (TPI) was calculated. A LDF probe was then fixed to the bottom of the first toe and cutaneous blood flow was measured continuously before, during, and after femoral artery occlusion by the thigh cuff. The occlusion time was 3 and 6 minutes. For the clinical study, thirty-three lower limbs with arterial occlusive disease were selected. During the vascular surgery, the LDF probe was attached to the bottom of the first toe and cutaneous blood flow was monitored continuously before, during, and after the vascular clamping. In the fundamental experiment, after the release of the occlusion, the maximum blood flow of the reactive hyperemia (peak flow) appeared. The period between the release of the occlusion and the peak flow was called the peak time. When the occlusion time was longer, the reactive hyperemia appeared later and was bigger. When TPI decreased, the peak time lengthened and the peak flow after a 6-minute occlusion decreased. In the clinical study, the more severe the degree of the preoperative limb ischemia was, the longer was the peak time. The longer the intraoperative clamping time, the longer the peak time. In conclusion, postocclusive reactive hyperemia during vascular surgery was influenced by the degree of the preoperative limb ischemia and the length of the vascular clamping time.

Journal Article↗
PubMed1998

Cerebral blood flow changes in the primary motor and premotor cortices during hyperventilation.

The aim of this study was to clarify the regional differences in cerebral blood flow (CBF) change during hyperventilation by using H2(15)O and positron emission tomography (PET). Eight healthy volunteers (age: 63.0 +/- 8.9 yr.) were studied. Regional CBF was measured by the H2(15)O autoradiographic method and PET. Statistical parametric maps (SPM) and conventional regions of interest (ROI) analysis were used for estimating regional CBF differences in the normocapnic state with normal breathing and the hypocapnic state induced by hyperventilation. Total CBF decreased during the hypocapnic state. The SPM revealed that primary motor and premotor cortices were significantly activated by hyperventilation. In these areas absolute CBF values were significantly higher than those in the temporal, occipital and parietal lobes in the hypocapnic state, but there were no significant regional differences in the normocapnic state. In the hypocapnic state induced by hyperventilation, the primary motor and premotor CBF shows combined changes with vasoreaction to hypocapnia and increase in activation due to hyperventilation.

Aged↗
PubMed1998

Advances in perinatal medical care--from our experience.

In the last 30 years, maternal and perinatal mortality rates have markedly improved in Japan. These results are supported by the advanced technologies and newly developed treatments in obstetric and neonatal medicine, the evidence of which will be described through the authors' experiences. Ultrasound-guided treatments for fetuses and pediatric surgery for extremely tiny infants have been performed with cooperation among cardiac surgeons, anesthesiologists and perinatologists. The remarkable achievements in neonatal medicine are surfactant replacement therapy, application of high frequency oscillation (HFO) respirator, nitric oxide and extracorporeal membrane oxygenation (ECMO) systems and transcutaneous blood gas monitoring. The possibility to have a safe pregnancy and delivery arose for women with severe medical complications such as diabetes mellitus (DM), heart diseases, and hemo-dialysis, factors formerly regarded as contraindications to pregnancy. The accumulative data of these high-risk pregnancies treated in our center are introduced. It is noted that molecular mechanisms in fetal growth have been elucidated to some extent. The insulin-like growth factor I (IGF-I) and IGF-binding protein 1 (IGFBP1) system, and cytokines, are involved in the fetal growth. Newly developed treatments such as urinary trypsin inhibitor (Urinastatin) for prevention of preterm delivery and amnioinfusion to cases of preterm premature rupture of the membrane are summarized. Finally, the reference to advanced medicine and its side effects lead to broad discussions regarding the future development of perinatal medicine.

Adolescent↗
PubMed1998

Giant cell tumor of the sphenoid bone: long-term follow-up of two cases after chemotherapy.

BACKGROUND: Giant cell tumors rarely occur in the sphenoid bone. When they do occur in the base of the skull, surgical treatment is frequently difficult and therefore, the use of adjuvant therapy is important. However, there remains no optimal management regimen for giant cell tumors of the sphenoid bone. CASE DESCRIPTION: Two cases of a giant cell tumor involving the sphenoid bone that responded well to chemotherapy using adriamycin after a partial removal of the tumor are presented. In the first patient, the tumor was partially removed via a transcranial subfrontal approach and a transnasal transsphenoidal approach. In the second patient, the tumor was partially removed through a transcranial subfrontal approach. Both tumors demonstrated histologic features typical of giant cell tumors. The patients subsequently received adjuvant chemotherapy using adriamycin alone in the first patient, and chemotherapy combined with radiotherapy in the second patient. Partial regression of the tumors was later confirmed on a computed tomography (CT) scan after chemotherapy. In both patients, tumors have been stable for more than 12 years despite an incomplete removal of the tumors. CONCLUSION: Based on the above findings, postoperative adjuvant chemotherapy using adriamycin may be effective for incompletely resected giant cell tumors of the sphenoid bone.

Adult↗
PubMed1998

Evaluation of acoustic properties of the live human smooth-muscle cell using scanning acoustic microscopy.

This study was performed to measure the acoustic propagation speed in live human aortic smooth-muscle cells (HASMC), using scanning acoustic microscopy (SAM) and a novel measurement theory that permits the measurement of the acoustic propagation speed in biological samples of unknown thickness. C-mode and X-Z-mode images of HASMC under three different conditions: growing (G); differential (D); and on hypotonic loading (H), were acquired using 100-MHz, 450-MHz and 600-MHz ultrasound. The images exhibit features related to the cell surface curvature and intracellular structure. The theory supporting the methodology is derived in this article and makes use of the interference fringes within the focusing lens of the high-frequency transducer. The propagation speed in the cells was calculated from the location of the interference fringe on the C-mode images and the fringe shift on the X-Y-mode images with 450-MHz ultrasound. The propagation speed in D (1624 +/- 16 m/s) was significantly higher than those in G (1571 +/- 14 m/s, p < 0.05) and H (1585 +/- 8 m/s, p < 0.05). Scanning acoustic microscope measurements, along with the described theory, are useful for studying the acoustic properties of live cells ex vivo and have applications in both pathophysiology and biomechanics.

Acoustics↗
PubMed1998

Flow cytometric method to detect lymphocyte transformation in drug-allergic hepatic injury.

Flow cytometric methods for the analysis of incorporated bromodeoxyuridine are extremely rapid and simple. We investigated whether these methods were useful for detecting drug-allergic hepatic injury in 18 patients with drug-allergic hepatic injury, 18 healthy controls, and 9 nonallergic patients receiving drugs. Peripheral blood mononuclear cells were stimulated with drug solutions. Incorporation of bromodeoxyuridine was detected after labeling with FITC, and S-phase cells were counted by flow cytometry. Percentages of S-phase cells in drug-stimulated culture minus those in spontaneous cultures were less than 1% in both healthy controls and nonallergic patients receiving drugs. Taking 1% as the upper limit, 13 patients (72%) were judged as positive. After the in vitro addition of interleukin-2, two patients among five who had been judged as negative were judged as positive. Lymphocyte transformation test by flow cytometry may be useful in the diagnosis of drug-allergic hepatic injury.

Case-Control Studies↗
PubMed1998

Positional cloning of the gene for Nijmegen breakage syndrome.

Nijmegen breakage syndrome (NBS), also known as ataxia-telangiectasia (AT) variant, is an autosomal recessive disorder characterized by microcephaly, growth retardation, severe combined immunodeficiency and a high incidence of lymphoid cancers. Cells from NBS patients display chromosome instability, hypersensitivity to ionizing radiation and abnormal cell-cycle regulation after irradiation, all of which are characteristics shared with AT. Recently, the NBS locus was mapped at 8q21 by two independent approaches, complementation studies and linkage analysis. Here, we report the positional cloning of the NBS gene, NBS1, from an 800-kb candidate region. The gene comprises 50 kb and encodes a protein of 754 amino acids. The amino-terminal region of the protein shows weak homology to the yeast XRS2, MEK1, CDS1 and SPK1 proteins. The gene is expressed at high levels in the testes, suggesting that it might be involved in meiotic recombination. We detected the same 5-bp deletion in 13 individuals, and conclude that it is likely to be a founder mutation.

Amino Acid Sequence↗
PubMed1998

A longitudinal study of the relationship between attributional style, life events, and depression in Japanese undergraduates.

A longitudinal design was used to investigate the relationship between attributional style, life events, and depression in Japanese undergraduates. The 1st hypothesis tested was that among those experiencing negative events, the students with a depressogenic attributional style would be more depressed than those with a nondepressogenic attributional style. The 2nd hypothesis tested was that among those experiencing positive events, the students with an enhancing attributional style would be less depressed than those with a nonenhancing attributional style. A total of 143 undergraduates responded to a depression scale, a life event questionnaire, and an attributional style questionnaire. The results, which generally supported the hypotheses, may reflect cultural differences between Japan and the United States.

Adult↗
PubMed1998

The effects of self-focus on negative mood among depressed and nondepressed Japanese students.

Self-focus may contribute to depression. Most investigations of the effects of self-focus on mood and cognition have taken place in the United States. Because cultural differences have been reported between the United States and Japan in both self-processes and depression, the U.S. studies should be replicated in Japan. In the present study, the effects of self-focus on mood were examined in a sample of Japanese university students. A total of 60 participants were assigned randomly to self-, other-, and social-focus conditions. Before and after the manipulation of their attention focus, the participants rated their moods as positive or negative. Under self-focus conditions, the depressed participants reported more negative feelings than did their nondepressed counterparts; however, in other-focus and social-focus conditions, no significant difference emerged between the 2 groups. Consistent with the U.S. studies, the negative effects of self-focus were limited to the depressed participants.

Adolescent↗