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T Asano

Publications and source records attributed to T Asano.

At least 541 records · Page 30Linked to original sources
PubMed1992

Expression of activities of two 20 alpha-hydroxysteroid dehydrogenase isozymes in rat corpora lutea.

The rat ovary contains two isozymes of 20 alpha-hydroxysteroid dehydrogenase (HSD-1 and HSD-2). In this study, the expression of activity of each isozyme was investigated in ovaries that contained a single generation of corpora lutea during pseudopregnancy. This condition was induced by cervical stimulation in rats that had been rendered anovulatory by housing them in a continuously lit environment. The total activity of cytosolic 20 alpha-HSD was lower in the ovaries of these pseudopregnant rats than in ovaries containing multiple generations of corpora lutea. In normal pseudopregnancy, HSD-1 activity was low on days 5 and 9 and increased markedly on day 15, whereas HSD-2 was lower than HSD-1 and did not vary throughout pseudopregnancy. However, on days 5 and 9 of continuous-light pseudopregnancy, low activity of HSD-1 only was detected; by day 15, HSD-1 activity had increased sixfold and HSD-2 activity could be detected. Immunohistochemical methods using a specific antibody recognizing both HSD-1 and HSD-2 revealed that the number of 20 alpha-HSD-positive luteal cells increased by day 15. Thus, the increase in total enzyme activity and appearance of HSD-2 activity observed at late pseudopregnancy was accompanied by an increase in the number of 20 alpha-HSD-positive luteal cells.

20-Hydroxysteroid Dehydrogenases↗
PubMed1992

Upregulation of GLUT2 mRNA by glucose, mannose, and fructose in isolated rat hepatocytes.

Previously, demonstrated that GLUT2 mRNA and protein are increased in liver of streptozocin-induced diabetic rats. To examine the mechanisms whereby GLUT2 mRNA is regulated, we cultured isolated hepatocytes in the absence and presence of various concentrations of glucose. Culture of hepatocytes in high glucose concentration (27.8 mM) for 20 h induced a 3.2-fold increase in GLUT2 mRNA levels compared with hepatocytes cultured without D-glucose. Interestingly, D-mannose and D-fructose could substitute for D-glucose to elevate the GLUT2 mRNA level, whereas 3-O-methyl-D-glucose, 2-deoxy-D-glucose, and sucrose, which were not metabolized or taken up by the cells, were without effect. Insulin had no significant effect on GLUT2 mRNA levels in hepatocytes in the presence or absence of D-glucose. Therefore, the regulation of the GLUT2 gene by D-glucose in hepatocytes is contrary to that reported for GLUT1 and GLUT4 genes, which are downregulated by D-glucose. These results also suggest that the elevated GLUT2 mRNA level observed in diabetic rat liver is due to the high blood glucose concentration rather than to insulin deficiency.

3-O-Methylglucose↗
PubMed1992

[Diagnostic accuracy of single photon emission CT in Alzheimer-type dementia].

To determine the diagnostic accuracy of single photon emission computed tomography (SPECT) with 123I-IMP in Alzheimer-type dementia (ATD), we studied 46 ATD patients and 23 healthy controls. The patients fulfilled the NINCDS-ADRDA criteria for probable or definite ATD and were classified as having mild, moderate, and severe ATD by neuropsychological examinations. To assess regional cerebral blood flow, we performed qualitative SPECT image analysis without any knowledge of the subject's clinical classification. The image was regarded as abnormal if cerebral blood flow was reduced in the unilateral or bilateral temporoparietal association areas, with or without any reduction of flow in other brain regions. The diagnostic sensitivity (abnormal image/patient) of 123I-IMP SPECT in mild, moderate, and severe ATD was 67%, 86%, and 92%, respectively. The specificity (normal image/control) was 91%, because an abnormal image was found in only 2/23 healthy controls. Eight ATD patients without reduced temporoparietal perfusion showed normal perfusion or frontal hypoperfusion. These results suggest that 123I-IMP SPECT may provide an accurate and sensitive diagnostic marker for ATD. The detection of these characteristic marker for ATD. The detection of these characteristic abnormalities of cerebral perfusion could well be applied to the clinical diagnosis of ATD.

Aged↗
PubMed1992

Effects of vasopressin and oxytocin on canine cerebral circulation in vivo.

In vivo experiments on the vasoactive effects of vasopressin and oxytocin on cerebral circulation were carried out in anesthetized dogs, using an electromagnetic flowmeter to measure vertebral blood flow and angiography to measure the internal diameter of the basilar artery. Direct bolus infusion of 1 pmol to 1 nmol of vasopressin or 10 pmol to 10 nmol of oxytocin into a femoral-vertebral artery shunt produced a dose-dependent decrease in vertebral artery blood flow without significantly affecting mean arterial blood pressure. Vasopressin was more potent than endothelin and neuropeptide Y, which have also been demonstrated to induce long-lasting decreases in vertebral artery blood flow. However, direct bolus infusion of vasopressin (100 pmol and 1 nmol) or oxytocin (1 nmol and 10 nmol) into the vertebral artery dilated major vessels including the vertebral, anterior spinal, and basilar arteries, as well as the circle of Willis and its main branches, while endothelin (1 nmol) and neuropeptide Y (5 nmol) caused no change in the diameters of major cerebral arteries. The V1 antagonist d(CH2)5tyrosine(methyl) arginine vasopressin suppressed the effects of both vasopressin and oxytocin. Vasopressin was over 10 times as potent as oxytocin in both assays. The vasodilatory effect of vasopressin, which may be mediated by an endothelium-dependent mechanism, was functionally damaged in dogs after experimental subarachnoid hemorrhage. These data suggest regional differences in the sensitivity and responsiveness of vasculature to vasopressin and oxytocin, and specifically that both peptides act through V1 receptors to decrease the resistance of large vessels and increase the resistance of small vessels.

Animals↗
PubMed1992

[Immunological study of interferon-gamma therapy for advanced renal cell carcinoma].

Immunologic and anti-tumor effects of interferon-gamma were studied in six patients with advanced renal cell carcinoma. A daily dose of 10 x 10(6) JRU/m2 of interferon-gamma (IFN-gamma) was given consecutively for five days and the treatment reiterated nine days later. Then the same dose was given every two days for three times and this regimen was also reiterated nine days later. Peripheral blood lymphocytes were analyzed before and one, three, five and eight weeks after the initial administration of IFN-gamma. Although the total number of lymphocytes and monocytes were not changed, CD8 (23.4 to 31.2%, p < 0.05), CD16 (12.4 to 19.3%, p < 0.01) and LeuHLA-DR (29.0 to 39.5%, p < 0.01) positive lymphocytes were significantly increased after the therapy. Non-induced LAK activity (0.6 to 10.8%, p < 0.05) and serum neopterin (3.5 to 10.8 nmol/L, p < 0.01) were also increased. These immunological parameters drastically changed during the consecutive administration of IFN-gamma, and tended to return to the previous value after this period. However, tumor regression was not clinically obtained. Our findings indicate that interferon-gamma stimulated the anti-tumor activity of the host, and administration of IFN-gamma is thought to be of immunological significance even in the advanced high stage cases.

Aged↗
PubMed1992

Evaluation of liver tumors using fluorine-18-fluorodeoxyglucose PET: characterization of tumor and assessment of effect of treatment.

To evaluate glucose metabolism in patients with tumors involving the liver, 35 patients with liver lesions had PET using 18F-2-fluoro-2-deoxy-D-glucose (FDG). FDG (148 MBq) was injected and radioactivity of the tumor was scanned dynamically by PET. The rate constants (k1, k2, k3, k4) of FDG in a metabolic model were calculated. The results were compared to hexokinase activity in the excised tumor specimens. k3 was found to reflect tumor hexokinase activity. When k3 was used as an index (cut-off value: 0.025), it was possible to distinguish benign and malignant tumors. k4 was significantly higher in hepatocellular carcinoma. By using k3 and k4 as indices, one could assess the degree of differentiation of hepatocellular carcinoma. After treatment, k3 decreased according to the effectiveness of therapy and thus may be a useful index for quantitatively assessing tumor viability.

Adenoma, Bile Duct↗
PubMed1992

[The effect of FK506 on segmental pancreas allograft in mongrel dogs].

FK506 is a potent immunosuppressive agent on experimental and clinical organ transplantation. We studied the the effect of this agent on segmental pancreas allograft in mongrel dogs. Graft survival was prolonged significantly with continuous administration of FK506, 0.3mg/kg/day intramuscular and 1.0mg/kg/day orally. However such symptoms as loss of appetite, nausea and extreme emaciation were observed and caused death. While bolus therapy of FK506 (3 days administration with the dose of 1.0mg/kg i.m. from 4 to 6 day postoperatively) showed the same immunosuppressive effect as continuous therapy and less side effect. Furthermore it was suggested that FK506 plasma levels were concerned with the appearance of side effect. In conclusion, the administration of FK506 with plasma level monitoring was thought to be useful on pancreas transplantation.

Animals↗
PubMed1992

[Cerebral hemodynamic difference between early- and late-onset Alzheimer's disease by circumferential profile analysis with 123I-IMP brain SPECT].

We conducted investigation to determine whether early- and late-onset Alzheimer's disease differ pathophysiologically. Five patients with the early-onset (65 years and under) of the disease and 11 with the late-onset (65 years and over) of the disease were studied by single photon emission CT (SPECT) with N-isopropyl-p-[123I]iodoamphetamine (IMP). Circumferential profile analysis (CPA) was performed to examine differences in the predominant hypoperfusion in the temporoparietal lobe, which is considered to be functionally damaged the most in Alzheimer's disease. The Xm values, calculated from gradients between the motor sensory or occipital cortices and temporoparietal cortex in the circumferential profile curve, were compared in both groups. The Xm values for the patients with early- and late-onset Alzheimer's disease were 6.81 +/- 2.10 (count/degree) and 3.28 +/- 1.58, respectively, the difference being significant. Our results suggest that functional abnormalities in the temporoparietal area severer in early- than late-onset Alzheimer's disease and that the application of CPA to IMP SPECT is useful to elucidate the pathophysiological difference between each of the disease.

Aged↗
PubMed1992

[Combined superior-transseptal approach to the mitral valve].

We report a technique to improve exposure of the mitral valve apparatus. This technique that combines superior left atriotomy and interatrial septotomy can be helpful in patients with a small left atrium and reoperation. It has been used effectively in five patients and potential complication with this procedure has not occurred. The operative technique and indication are discussed in this paper.

Adult↗