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Biomedical subjects

M Kotani

Publications and source records attributed to M Kotani.

At least 145 records · Page 8Linked to original sources
PubMed1980

Suppression of immune response by isolation of the bursa of Fabricius from environmental stimuli.

When the bursa of Fabricius was isolated from environmental stimuli across the bursal epithelium by clipping the bursal duct on the 19th day of incubation, marked retardation was observed both in the bursal development and in the maturation of the immune reactivity. Neither necrotic changes nor involution in the bursa was, however, observed at any stage examined after clipping the bursal duct. Lymphopoiesis in the bursa and the immune reactivity of these chickens gradually increased with age, although they were constantly lower than those of controls. These results suggest that environmental stimuli across the bursal epithelium play an important role in teh amplification mechanisms of B-cell differentiation in the bursa.

Animals↗
PubMed1980

The migration of presumptive primordial germ cells through the endodermal cell mass in Xenopus laevis: a light and electron microscopic study.

Presumptive primordial germ cells (pPGCs) were examined during migration from their deep endodermal position to the endodermal crest in Xenopus laevis, using light and electron microscopy with Epon sections, and several morphological characteristics of pPGCs, associated with their migration, were revealed. pPGCs displayed polymorphism, with smooth contours. The intercellular space around the PGCs was large and variable in width and cytoplasmic processes from pPGCs were occasionally observed in it. It was shown quantitatively that pPGCs at the migratory stage had a tendency to move with the leading end, towards which the nucleus was localized, dragging the germinal plasm behind. These polarized pPGCs were frequently associated with large intercellular spaces, both at their leading and trailing ends. Cytoplasmic processes of polarizing pPGCs found in the large intercellular space at the leading end were conspicuous. Ultrastructurally, the nuclei of pPGCs were euchromatic, and the nucleolus was prominent. The germinal plasm at the light microscope level corresponded to the cytoplasmic area near the nucleus where a large number of mitochondria with well-developed cristae and most of the other organelles were aggregated. Centrioles and centriole-associated microtubules observed in the aggregate were thought to be important structures responsible for the cell polarization mentioned above. It was demonstrated quantitatively that the size of mitochondria in pPGCs was larger on average than that of mitochondria in neighbouring somatic endodermal cells. Numerous irregularly shaped small yolk platelets characterized pPGCs. These ultrastructural features suggested that pPGCs were in an activated metabolic state. It was concluded that the migration of pPGCs was attributable to active movement with high cell metabolism, causing the formation of cell processes and intracellular polarization.

Animals↗
PubMed1980

The increase in permeability of postcapillary venules in lymph nodes subjected to the regional graft-versus-host reaction.

The changes in permeability of blood vessels in the draining lymph nodes of the footpads undergoing a regional graft-versus-host, host-versus-graft, or antisheep erythrocytes reaction were examined 30 minutes after intravenous injection of Pelikan Ink. Massive leakage of carbon particles was seen only in the postcapillary venules where endothelial cells became flattened. This was observed in lymph nodes 3 to 7 days after induction of the regional graft-versus-host reaction and occurred mainly through intercellular gaps in the endothelium. This transient increase in permeability of postcapillary venules was apparently independent of cellular emigration. No obvious increase in carbon permeability was observed in lymph nodes subjected to the regional host-versus-graft reaction, whereas the uptake of cellular and noncellular elements of the blood by endothelial cells of postcapillary venules was greatly increased. There was no increase in carbon permeability in antisheep erythrocyte-stimulated lymph nodes.

Animals↗
PubMed1979

Concurrent hypersecretion of aldosterone and cortisol from the adrenal cortical adenoma.

Hypertension, hypokalemia, suppressed plasma renin activity and increased plasma aldosterone were found in a middle-aged woman. Following removal of the tumor in the left adrenal gland these abnormalities disappeared. Concurrently, however, the plasma cortisol level did not show normal diurnal change, although the value at 6 A.M. was within the normal range. Administration of 2 mg dexamethasone failed to depress the plasma cortisol level and urinary 17-OHCS concentrations. Postoperatively, plasma cortisol and urinary 17-OHCS were below normal. Histologic examination of the tumor indicated the presence of two types of adenoma cells; one was a large watery clear cell with rich lipid and possibly with aldosterone secretion and the other was an acidophilic cell with poor lipid and possibly with cortisol secretion. It is suggested that, in addition to oversecretion of aldosterone, the tumor autonomously secreted cortisol, although the amount of cortisol secreted was not large enough to produce typical Cushing's syndrome.

Adenoma↗
PubMed1979

Peritoneal macrophages introduced into mouse foot pads enter the germinal center of regional lymph nodes nonspecifically.

Male mice were injected into their foot pads with sheep erythrocytes (SRBC) to form lymph follicles in the germinal centers in the popliteal lymph nodes. 4 weeks later, peritoneal macrophages labeled with carbon from syngeneic donors sensitized with SRBC or typhoid-paratyphoid bacilli (TAB) were separately injected into the foot pads as well. The popliteal lymph nodes were histologically examined at 6 h to 5 days after injection. Labeled macrophages appeared in the marginal sinus, migrated straight across the cortex from the marginal sinus to the lymph follicles and then entered the germinal centers. There was no difference in the mode of appearance, migration and localization of labeled macrophages in the regional lymph nodes between the mice given labeled macrophages from SRBC-sensitized donors and those given macrophages from TAB-sensitized donors. The entrance of lymph macrophages into the germinal centers of the regional lymph nodes would be immunologically nonspecific. After the injection of Pelikan ink into the foot pads, the macrophages which have taken up carbon in the peripheral tissue reached the regional lymph nodes via the afferent lymphatics and then entered the germinal centers, mainly through the medullary pole of the lymph follicles, after migrating along their immediate exterior from their marginal sinus to their medullary pole.

Animals↗
PubMed1979

Effects of estrogen on the lymphoid regeneration and immune response in irradiated and marrow-reconstituted mice.

Various doses of estriol (E3) were given to mice intraperitoneally, immediately after lethal irradiation and marrow reconstitution. The assessment of the plaque-forming cell (PFC) response to sheep erythrocytes in the spleen and the histological assessment of lymphoid tissues were carried out 30 days later. The effects appeared to be dose-dependent and resulted in a marked suppression of the PFC response. The depletion of lymphocytes was dramatic and dose-dependent in the thymus, and in the thymus-dependent and in the thymus independent areas of the peripheral lymphoid tissues. These results suggest that E3 acts on the differentiation of stem or precursor cells toweard both the populations of T and B lymphocytes. Although E3, given on day 7 after irradiation and marrow reconstitution, suppressed the lymphoid regeneration and PFC response markedly, E3 given on day 14 had no effect. On day 7 the majority of regenerating lymphoid tissues were large pyroninophilic cells and on day 14, small lymphocytes. These results suggest that the precursor or immature lymphocytes are sensitive to E3, while mature lymphocytes are resistant. Lymphoid regeneration and PFC response were retarded in mice irradiated and reconstituted with bone marrow cells from donors pretreated with E3. These results suggest that E3 acts on the stem or precursor cells capable to differentiate in the direction of lymphoid populations and reduce their number in the bone marrow.

Animals↗
PubMed1979

Virilizing adrenal adenoma stimulated by dexamethasone in a middle-aged woman.

In a middle-aged woman with virilizing adenoma, 2 mg dexamethasone increased urinary excretion of 17-ketosteroids (17-KS) and 17-hydroxycorticosteroids, whereas 8 mg dexamethasone increased urinary excretion only of 17-KS. With discontinuation of dexamethasone, 17-KS excretion returned to the predexamethasone level. Dexamethasone depressed the basal level of cAMP synthesis and basal testosterone production by the normal adrenal tissue in vitro. Dexamethasone also depressed the increase of cAMP produced by ACTH in the normal tissue. In contrast, dexamethasone increased basal cAMP synthesis and stimulated testosterone secretion in the tumor tissue. ACTH and dexamethasone were additive in their effects on cAMP and testosterone in the tumor tissue. It is suggested that dexamethasone acted directly on the adrenal tumor to stimulate steroid secretion in this patients.

11-Hydroxycorticosteroids↗
PubMed1979

Distribution and role of lymph vessels of the bursa Fabricii.

The fine distribution of lymph vessels in the bursa of Fabricius and the efferent lymph vessels coming from the bursa were demonstrated. The lymph vessels never entered lymphoid follicles, whereas the blood vessels pierced the cortex of lymphoid follicles and formed a network at the boundary between the cortex and medulla of lymphoid follicles. The lymph vessels commenced in the immediate exterior of lymphoid follicles. A large number of lymphoid cells were found in the lumen of the lymph vessels. Migration of lymphoid cells from the cortex of lymphoid follicles to the lymph vessels was also observed. Therefore, it was assumed that the lymph vessels of the bursa are important in the transport of lymphoid cells from the bursa to the blood stream.

Animals↗
PubMed1979

Sex differences in the formation of germinal centres in the rat thymus.

Rats of inbred DA strain were given 20 intraperitoneal injections of typhoid-paratyphoid bacilli at 10 day intervals. Thymic lymph follicles with germinal centres were formed in females but not in males. However, orchidectomy permitted the formation of large numbers of thymic lymph follicles with germinal centres in males. The formation of lymph follicles with germinal centres in the thymus was not affected by ovariectomy. These results would appear to suggest an inhibitory role of androgens on the formation of thymic lymph follicles with germinal centres. In addition, large numbers of plasma cells, mast cells, and reticular cells, or macrophages with haemosiderin in their cytoplasm, appeared in the parenchma of the thymus in close association with the formation of thymic germinal centres.

Animals↗
PubMed1979

Amplification of plaque-forming cells in the spleen after intracloacal antigen stimulation in neonatal chicken.

Neonatal chickens were primed by multiple or a single injection with sheep red blood cells (SRBC) into the cloacal lumen and then were challenged by intravenous injection with the same antigen. Direct plaque-forming cells (PFC) in the spleen were markedly increased shortly after intracloacal priming. This enhancing effect was antigen specific and was abolished by surgical bursectomy 24 h after intracloacal priming. A similar effect was also found in mature adult chickens, although the degree of enhancement was far less than that found in neonatal chickens. These results suggest that a certain stage of B-cell differentiation in the bursa of Fabricius (BF) is regulated by antigenic stimulation.

Aging↗
PubMed1978

An increase of pituitary 3', 5' cyclic adenosine monophosphate produced by estradiol benzoate in vitro: possible implication of this increase in the secretion of luteinizing hormone.

In an attempt to study the site and mechanism of action of estrogen in producing positive feedback control, porcine anterior pituitary slices were incubated in vitro in the presence of estradiol benzoate (EB). EB elevated pituitary cyclic AMP concentration within 5 min and augmented pituitary release of luteinizing hormone (LH). The magnitude of increase of cyclic AMP and LH release was related to the doses of EB used. Also, luteinizing hormone releasing hormone (LH-RH) elevated pituitary cyclic AMP concentration and stimulated pituitary release of LH. The magnitude of increase of cyclic AMP and LH release was inversely related to the doses of LH-RH used. EB and LH-RH were additive in increasing cyclic AMP. Progesterone and clomiphene citrate interfered with an increase of pituitary cyclic AMP produced by EB, but did not significantly affect the basal level of pituitary cyclic AMP. Testosterone propionate, human chorionic gonadotropin and hexestrol were without effect on either basal or stimulated level of pituitary cyclic AMP. Since cyclic AMP and dibutyryl cyclic AMP (DBC) stimulated LH release, it is suggested that EB directly stimulates the release of LH by augmenting cyclic AMP synthesis in the anterior pituitary.

Animals↗
PubMed1978

An increase of plasma triiodothyronine and thyroxine after administration of dexamethasone to hypothyroid patients with Hashimoto's thyroiditis.

In an attempt to study the effect of adrenal steroids on plasma thyroid hormone concentration in patients with Hashimoto's thyroiditis, 2 mg dexamethasone was administered for 2-4 weeks to 9 patients with normal plasma TSH, 3 patients with compensatory increase of plasma TSH, and 10 patients with a marked elevation of plasma TSH. Dexamethasone depressed plasma T4, T3, and TSH and reduced thyroid size in nine euthyroid patients, whereas a similar treatment did not affect plasma T3 and T4, but reduced plasma TSH and thyroid size in three patients with compensatory increase of plasma TSH. In contrast, dexamethasone elevated plasma T3 and T4 in 10 hypothyroid patients with a marked elevation of plasma TSH. The increase of T3 was more than that of T4, suggesting preferential secretion of T3. Plasma TSH was reduced, but was still above normal after administration of dexamethasone. It is suggested that the intrathyroidal autoimmune processes inhibiting thyroid hormone synthesis are significant in patients with more severe Hashimoto's thyroiditis, and that dexamethasone stimulated hormone synthesis by depressing the autoimmune processes.

Adolescent↗
PubMed1978

Effects of thyroid-stimulating hormone on human thyroid carcinoma and adjacent normal tissue.

Effects of TSH on the adenylate cyclase-cAMP system and some parameters of intermediary metabolism were investigated in human thyroid carcinoma and adjacent normal thyroid tissue. Basal adenylate cyclase activity and cAMP concentrations were significantly higher in carcinomatous tissue. Basal [1-14C]glucose oxidation, 32Pi incorporation into phospholipids, and organification of iodide were similar in both tissues. Stimulation of cAMP by TSH was significantly greater in normal compared to carcinomatous tissue. In neither tissue was there a good correlation between TSH stimulation of adenylate cyclase activity and cAMP concentrations. The TSH stimulation of 32Pi incorporation into phospholipids by TSH was significantly greater in normal tissue. The mean effect of TSH on iodide organification and glucose oxidation was similar in normal and carcinomatous tissue. Although specific binding of TSH was demonstrated in both normal and carcinomatous tissue, it did not correlate very well with stimulation of adenylate cyclase activity. Hormones other than TSH also augmented adenylate cyclase activity in two of the carcinomas. In individual patients, the relative responsivity of carcinomatous tissue compared to normal was not always consistent when all of the metabolic parameters were considered.

Adenylyl Cyclases↗
PubMed1978

Effect of thyroid hormone, actinomycin D, cycloheximide and puromycin on TRH-induced secretion of TSH, as studied by pituitary concentration of cyclic AMP and intrathyroidal colloid droplet formation.

In an attempt to study the functional relation between pituitary cyclic AMP and TSH secretion in response to thyrotropin releasing hormone (TRH) or thyroid hormone administration, pituitary concentration of cyclic AMP was measured by protein binding assay after in vivo and in vitro administration of test materials (TRH, thyroxine, triiodothyronine, actinomycin D, puromycin and cycloheximide singly or in combination). Small dose of TRH apparently augmented TSH secretion as evidenced by a marked increase of intrathyroidal colloid droplet, but failed to elevate the pituitary concentration of cyclic AMP. Triiodothyronine (T3) and thyroxine (T4) blocked an increase of TSH secretion produced by TRH, but they elevated pituitary concentration of cyclic AMP in vivo and in vitro. Actinomycin D (Act D), puromycin and cycloheximide elevated pituitary cyclic AMP concentration without stimulating TSH secretion. From the data accumulated, it appears that the measurement of total anterior pituitary concentration of cyclic AMP is not useful to evaluate the activity of TSH cells in response to thyroid hormone, TRH and TRH plus thyroid hormone.

Animals↗
PubMed1977

A device for expressing the serum insulin glucose relationship in diabetes, hyper- or hypothyroidsm, and chronic hepatitis.

When the serum insulin valves during a 50-gm oral glucose tolerance test were expressed as the function of glucose concentrations, a good linear relationship was found in normal subjects and in patients with diabetes, hyperthroidism, hypothroidism or chronic hepatitis. The insulin index calculated from the line representing this relationship was less than 100 in all 19 diabetic patients and most of the 13 hyperthyroid patients with oxyhyperglycemia, whereas it was more than 100 in the 14 normal subjects, the 4 hypothyroid patients, and the 8 patients with oxyhyperglycemia due to chronic hepatitis. The insulin index decreased with increasing maximal blood glucose concentration during the glucose tolerance test in diabetic patients. Furthermore, improvement in the insulin index was correlated with the effectiveness of sulfornylurea drugs in the diabetic group.

Adult↗