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Biomedical subjects

Y Baba

Publications and source records attributed to Y Baba.

At least 325 records · Page 18Linked to original sources
PubMed1980

Catecholamine-stimulated cyclic AMP formation in phenylethanolamine N-methyltransferase containing brain stem nuclei of normal rats and of rats with spontaneous genetic hypertension.

Stimultaion of cyclic AMP formation by epinephrine and norepinephrine has been studied in discrete areas of rat brain that include the epinephrine-containing brain stem nuclei C-1 and C-2. In the C-1 area, epinephrine-stimulated cyclic AMP formation was partially reversed by 100 microM phentolamine and by 10--100 microM propranolol or alprenolol and hence appeared to involve activation of a mixture of both alpha- and beta-adrenergic receptors as has been reported for other rat brain areas such as the cerebral cortex. However, in the C-2-area, the epinephrine and norepinephrine stimulated cyclic AMP formation involved the activation of a single receptor type which was alpha-like in character. Stimulation of cyclic AMP formation by epinephrine in the C-2 area was antagonized by nanomolar concentrations of both phentolamine and yohimbine. The epinephrine-stimulated formation of cyclic AMP in the C-2 but not in the C-1 area was augmented in a strains of rats which exhibit spontaneous genetic hypertension (SHR) vs. Wistar-Kyoto controls. It is suggested that the enhanced epinephrine-stimulated cyclic AMP formation in the C-2 area of SHR rats could be a physiological compensatory response to some other hypertension-causing lesion which, for example, results in chronically reduced epinephrine release or in ruduced availability of epinephrine at its postsynaptic receptor thereby leading to receptor supersensitivity. Supporting this possibility was the finding that treatment of SHRs and control animals and reserpine resulted in enhancement of epinephrine-stimulated cyclic AMP formation in the C-2 area of control rats, essentially obliterating the difference between control and SHR. The findings are also interepreted as supporting the involvement of epinephrine neurons in central vaso-depressor mechanisms.

Adrenergic alpha-Antagonists↗
PubMed1980

Hemopoiesis recovery of irradiated rats conjugated with normo- and polycythemic animal by aortic anastomoses.

The experiment was designed to observe the possible relation between myelopoietic and erythropoietic activities of circulating nucleated cells. Wistar rats were lethally irradiated with 60Co, 100 r once. Two days after irradiation the bone marrow cells had faded completely. At this stage animals were conjugated with normocythemic or polycythemic rats by aortic anastomoses. After conjugation the aplastic bone marrow of the irradiated animal rapidly regained its hemopoietic activity in cases having normocythemic and polycythemic partners. Active erythropoiesis and myelopoiesis were found 96 h after parabiosis in those having normocythemic partners. In animals having polycythemic partners, however, erythropoiesis was successfully suppressed. An increase in lymphoid cell numbers was found in place of decreased erythroid cells, but there was no change in the myeloid cell proliferation rate. No hemopoietic precursor cells or immature cells were found in circulating blood all through the experimental period before and after parabiosis. The data suggest that circulating nucleated cells have marked erythropoietic activity. Erythropoietic cells may be somehow related to lymphoid cells independent of myelopoietic activity.

Animals↗
PubMed1980

Immunologic studies on Werner's syndrome.

Five patients with Werner's syndrome were studied to elucidate the relationship between the immune system and the ageing process. Three of five patients had neoplasms such as fibrosarcoma, meningioma and thyroid adenoma but none of the five patients manifested symptoms and signs suggestive of typical autoimmune disorders. Most immunohaematological data were normal; however, two patients exhibited diminished lymphocyte functions such as a significant (P less than 0 . 05) reduction in pokeweed mitogen (PWM) induced B cell differentiation, a slightly decreased response to Con A- or mitomycin-treated allogeneic lymphocytes and naturally occurring serum antibody to T cells. While these immunological changes were quantitatively small, subnormal levels of immune functions were detected. Cultured fibroblasts exhibited a decrease in clonal growth potentials and elongation of newly synthesized DNA, a decreased expression of HLA antigens, and a diminished secretion of beta 2-microglobulin.

Adult↗
PubMed1979

Distribution of PNMT and epinephrine in the medulla oblongata of normotensive and spontaneous hypertensive rats.

The distribution of the Epinephrine forming enzyme (PNMT) activity and Epinephrine (E) levels was investigated in the medulla oblongata of spontaneous hypertensive rats (SH-rats) and in two normotensive strains, namely Wistar Kyoto rats (WK-rats) and Wistar rats. The PNMT activity increases progressively from the caudal to rostral parts in the C1 and C2 regions of the medulla oblongata. The enzyme activity and the E levels are in all parts of the C1 and C2 regions higher in Wistar rats than in WK-rats. The PNMT activity in all parts of the C2 region (with the exception of the caudal region), and in the middle part of the C1 region is higher in SH-rats than in WK-rats. The E levels in the SH-rats are higher than in WK-rats in the mediocaudal parts of the C2 and C1 regions.

Animals↗
PubMed1979

Interaction between thyroid-stimulating immunoglobulins and thyrotropin receptors in fat cell membranes.

In the TSH radioreceptor assay to study the interaction between Graves' immunoglobulins (Ig) and TSH receptors in guinea pig fat cell membranes, Graves' Ig were found to inhibit [125I]TSH binding to fat cell membranes in a dose-dependent manner. Scatchard analysis of [125I]TSH displacement curves by Graves' Ig indicated a single population of the binding sites in fat cell membranes, in contrast to two populations of TSH-binding sites in the membranes. Displacement of [125I]TSH bound to fat cell membranes by both Graves' Ig and unlabeled TSH were time and temperature dependent, with similar dissociation curves, suggesting a specific binding of Graves' Ig to the membrane sites related to the TSH receptor in the fat cells. Such Ig are referred to as fat cell-binding Ig, to be distinguished from the thyroid-stimulating Ig (TSI) detected by TSH radioreceptor assay using human thyroid membranes. Both fat cell-binding Ig and TSI were detected in the sera of a great majority of untreated patients with Graves' disease. A significant correlation was found between both values (r = 0.80; n = 19; P less than 0.001). According to these results, TSI might represent an autoantibody to the membranes associated with the TSH receptor of the target tissues without a strict organ specificity.

Adipose Tissue↗
PubMed1979

Effects of alpha- and beta-adrenergic blockers on binding of thyrotrophin to fat cell membrane.

Alpha- (phentolamine) and beta-adrenergic blocking agents (propranolol) and quinidine similarly enhance the specific binding of TSH to the guinea pig fat cell membranes over the concentration range of 2 X 10(-4) to 4 X 10(-3) M, increasing the binding affinity of TSH to the membranes. The percentage bound increased from 8% in the absence of agents to 32% (phentolamine), 29% (propranolol) and 24% (quinidine), respectively in the presence of these agents (1.5 X 10(-3) M). Each minimal detectable quantity of TSH was approximately 10 microU per tube in the presence of these agents (10(-3) M) as compared to 100 microU per tube in their absence. Both phentolamine and propranolol appeared to enhance the TSH binding to fat cell membranes through membrane-active, non-specific effects besides their alpha- and beta-adrenergic blocking activities.

Adipose Tissue↗
PubMed1979

Higher levels of erythrocyte membrane microviscosity in diabetes.

Significantly higher levels of erythrocyte membrane microviscosity (MV) [n-: 5.22 +/- 0.17 (4.70--5.92), mean +/- SD (range), poise, N = 67, P less than 0.005] measured by fluorescence depolarization using 1,6-diphenyl-1,3,5-hexatriene as a fluorescent probe were found in diabetic patients when compared with normal controls [5.05 +/- 0.15 (4.70--5.29), N = 22]. No significant differences in MV existed between males and females, nor was MV significantly correlated with diabetic age, duration of diabetes, plasma cholesterol, cholesterol/phsopholipid ratios, and plasma lecithin:cholesterol acyltransferase activities. No significant difference in MV was observed between groups with or without diabetic retinopathy. There was, however, significantly higher MV [5.29 +/- 0.19 (5.00--5.92), N = 20, P less than 0.05] in the group with fasting blood glucose (FBG) greater than or equal to 140 mg/dl than that [5.19 +/- 0.15 (4.70--5.46), N = 47] in the group with FBG less than 140 mg/dl. The changes in erythrocyte membrane MV presented in this study appear to be related to the current metabolic control of diabetic patients and are considered to be one of the factors responsible for the reduced erythrocyte deformability in diabetes.

Diabetes Mellitus↗