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Biomedical subjects

Y Ichikawa

Publications and source records attributed to Y Ichikawa.

At least 829 records · Page 46Linked to original sources
PubMed1979

Accumulation of eosinophils and monocytes in lymphoid organs of chick-embryos. I. Effect of antigenic stimulation.

The effect of antigenic stimulation on the migration pattern of eosinophils and monocytes was studied during the embryonic stage in chickens. On the 13th embryonic day, chickens were injected with sheep red blood cells as antigen into the allantoic cavity and the relative frequency of oxidase positive cells (OPC) was determined as the total number of eosinophils and monocytes in the bursa of Fabricius, spleen, and thymus. Three and five days after the antigenic stimulation, the frequencies of OPC increased in both the spleen and thymus and then decreased to the normal level just before hatching. However, bursal frequencies of OPC were always low in both the cortex and medulla when compared with the controls. These events indicated that eosinophils and monocytes accumulated in the spleen and thymus after the antigenic stimulation. Furthermore, different frequencies of OPC among the embryonic lymphoid organs showed different responses in the migration of eosinophils and monocytes.

Animals↗
PubMed1979

Accumulation of eosinophils and monocytes in lymphoid organs of chick-embryos. II. Effect of mitogenic stimulation.

The mitogen effect on migration of eosinophils and monocytes was studied in embryonic chickens. On the 13th embryonic day, chickens were injected with mitogens, such as concanavalin A (Con A), phytohemagglutinin-P (PHA-P), and lipopolysaccharide (LPS), into the allantoic cavity, and the mitogenic effect was estimated from the relative frequencies of eosinophils and monocytes by enumerating the number of oxidase positive cells (OPC) in the spleen, thymus, and bursa of Fabricius. Splenic frequencies of OPC increased in the embryos treated with mitogens. Similar influences were also detected in the thymic OPC. Higher responses were seen on the 18th embryonic day in the number of splenic OPC when embryos were treated with Con A or PHA-P than with LPS. These findings suggest that Con A and PHA-P are preferential OPC accumulation promoters. However, bursal frequencies of OPC in the cortex were low after mitogenic stimulations when compared with controls, although appreciable responses were detected in the bursal medulla after LPS stimulation. These results suggest that the migration pattern in the population of eosinophils and monocytes is affected not only by T cell mitogens but is also derived from LPS stimulation.

Animals↗
PubMed1979

Inhibitory effects of corticosterone on cell proliferation and steroidogenesis in the mouse adrenal tumor cell line Y-1.

Monolayer cultures of mouse adrenal tumor cell line Y-1 have been used to investigate the effects of glucocorticoid on cell replication, [3H]thymidine incorporation into the trichloroacetic acid-precipitated cell fraction, steroidogenesis, and the ACTH receptors of adrenocortical cells. Corticosterone at a concentration of 5.0--50 micrograms/ml inhibited cell replication and [3H]thymidine incorporation into trichloroacetic acid-precipitated cell fraction in a dose-related manner. Corticosterone at a concentration of 0.5--50 micrograms/ml inhibited ACTH-induced steroidogenesis in a dose-related manner. Steroids which do not possess glucocorticoid action did not show such inhibitory effects on cell replication and steroidogenesis of Y-1 cells. The characteristics of the ACTH receptors of these cells remained unaffected by corticosterone. Our findings suggest that synthesized or secreted glucocorticoid may play an important role in the direct regulation of proliferation and function of adrenocortical cells under physiological conditions.

Adrenal Gland Neoplasms↗
PubMed1979

Direct inhibitory effect of dexamethasone on steroidogenesis of human adrenal in vivo.

A rapid ACTH test was used to investigate the direct effect of glucocorticoid on the steroidogenesis by the adrenal cortex in man. The plasma cortisol response to 250 microgram iv synthetic alpha-ACTH-(1--24) (Cortrosyn) was determined in normal subjects pretreated with 2 and 12 mg dexamethasone. The 15- and 30-min increments in plasma cortisol levels in response to ACTH injection after pretreatment with 12 mg dexamethasone were significantly suppressed compared to values obtained after pretreatment with 2 mg dexamethasone. The present study suggests that there is a direct inhibitory effect of glucocorticoid on adrenocortical steroidogenesis in man.

Adolescent↗
PubMed1979

Plasma cortisol profiles in Cushing's syndrome.

Plasma cortisol profiles were studied by the frequent sampling method in 5 patients with Cushing's disease (CD), 7 patients with Cushing's syndrome due to adrenocortical adenoma (AA), and one patient with bronchogenic carcinoma. Plasma ACTH was measured by radioimmunoassay at 10 min intervals in 2 of the subjects. In CD, there was distinct episodic secretion of cortisol and ACTH; the coefficients of variation about the mean plasma cortisol concentration ranged from 24 to 27%; plasma ACTH ranged from zero to 455 pg/ml with a mean of 94 pg/ml. In AA, the tumour secreted cortisol at a constant rate with little fluctuation; the coefficients of variation of plasma cortisol concentration ranged from 8 to 14%; plasma concentrations of ACTH were always near zero. In the patient with bronchogenic carcinoma, the coefficient of variation of cortisol was 14%. These results were apparent even in profiles of plasma cortisol concentrations measured over only a 6 h period. It is concluded that characteristics of plasma cortisol and ACTH secretory patterns are helpful in differentiating Cushing's syndrome of differing aetiology.

Adenoma↗
PubMed1979

In vitro microbiological evaluation of TEI-1194 and TEI-2012, novel antipseudomonal semisynthetic penicillins.

TEI-1194, sodium 6-[D-(-)-alpha-(coumarin-3-carboxamide)-phenylacetamide] penicillanate and TEI-2012, sodium 6[D-(-)alpha-(8-hydroxy-coumarin-3-carboxamide)-phenylacetamide] penicillanate are new semisynthetic penicillin derivatives both possessing a broad spectrum of in vitro antibacterial activities. Minimal inhibitory concentrations of both agents were compared with carbenicillin. TEI-1194 and TEI-2012 were clearly found to have more potent activities especially against Pseudomonas aeruginosa than carbenicillin. At a concentration at 6.25 micrograms/ml, 85 approximately 90% of a total of 50 strains of clinically isolated P. aeruginosa were inhibited by TEI-1194 and TEI-2012, whereas carbenicillin had no effect. Evaluation of the antibacterial activity against a series of mutants producing different levels of beta-lactamases and test of the susceptibilities to some beta-lactamases demonstrated that TEI-1194 and TEI-2012 had low susceptibility to various cephalosporinases. However, both compounds were susceptible to penicillinase from Klebsiella pneumoniae H-2 at a rate of about 15% of penicillin-G taking its absolute rate as 100.

Bacteria↗
PubMed1979

Ontogeny of spontaneous antigen-binding cells in developing chick embryos.

Bursal and splenic lymphocytes in developing chick embryos were examined for the number of antigen binding cells (ABC) which could form rosettes with red blood cells from sheep, guinea-pig, rabbit or dinitrophenylated sheep red blood cells (DNP-SRBC). The kinetics of the development of bursal ABC to rabbit red blood cells (RRBC) did not vary significantly with age of embryo examined, and its frequency was constantly high. The number of cells which bind to SRBC, guinea-pig red blood cells (GPRBC) or DNP-SRBC was low in the bursa and increased in an approximately linear fashion with the age of embryo. With the exception of RRBC-ABC, similar results were obtained with splenic ABC. Furthermore, the frequencies of ABC were higher in the spleen than in the bursa. These events suggest the antigen-independent generation of clonal diversity during the developmental stage of chick embryos.

Animals↗
PubMed1978

Localization of cytochrome P-450-linked mixed function oxidase and steroid hydroxylations within zones of bovine adrenocortices.

The localization of contents and activities of components of cytochrome P-450-linked mixed function oxidase system and the hydroxylation of steroids in mitochondria and microsomes within zones of adrenocortices was investigated. NADPH-adrenodoxin reductase activity was higher in the zona glomerulosa than in the other zones. Adrenodoxin content was present at high concentration in the zona fasciculata. The localization of cytochrome P-450 within zones of adrenocortices has already been reported (Ichikawa, Y., Kuroda, M. and Yamano, T. (1970) J. Cell Biol 45, 640--653). The zona fasciculata contained more mitochondrial and microsomal cytochromes P-450 than the zona glomerulosa or zona reticularis. Cleavage activity of the side chain of cholesterol was found in three zones. However, particularly high activity was observed in the zona fasciculata and zona reticularis. 11beta-Hydroxylation was found in the zona glomerulosa. 21-Hydroxylation activity was especially higher in the zona fasciculata than in the other zones.

Adrenal Cortex↗
PubMed1978

Crystalline reduced nicotinamide adenine dinucleotide phosphate-adrenodoxin reductase from pig adrenocortical mitochondria. Essential histidyl and cysteinyl residues of the NADPH-binding site and environment of the adrenodoxin-binding site.

Pig NADPH-adrenodoxin reductase was crystallized from pig adrenocortical mitochondria and its physicochemical properties were investigated. Pig NADPH-adrenodoxin reductase is a typical flavoprotein. Its optical absorption spectrum showed peaks at 272, 377, and 450 nm in the oxidized form. The adrenodoxin reductase contained one FAD per mol. The molecular weight was 49,000. The isoelectric points of the adrenodoxin reductase and its complex with adrenodoxin were 5.3 and 4.6, respectively. Pig NADPH-adrenodoxin reductase, unlike bovine NADPH-adrenodoxin reductase, was found to be free of carbohydrate. The fluorescences of tryptophanyl residues and FAD of the adrenodoxin reductase were quenched by holo- and apo-adrenodoxins. The NADPH-binding site of the adrenodoxin reductase was examined by photooxidation and selective chemical modifications with diethyl pyrocarbonate and sulfhydryl reagents. The results indicate that a histidyl and a cysteinyl residue of the adrenodoxin reductase are essential for the NADPH-binding site. The circular dichroism spectrum of the adrenodoxin reductase showed negative ellipticity in the visible region. Spur formation was observed between pig and bovine NADPH-adrenodoxin reductases against the antibody to bovine NADPH-adrenodoxin reductase in Ouchterlony double-diffusion agar plates. The antibody did not interact with spinach ferredoxin-NADP+ reductase.

Adrenal Cortex↗
PubMed1978

Immune reconstitution in the immunodeficient chicken by transfer of embryonic lymphoid cells.

Embryonic chickens were rendered immunodeficient by in ovo injection of homologous IgM on the 10th embryonic day. The immunodeficient embryos were intravenously given lymphoid cells taken from normal embryonic bursa, spleen or thymus on the 15th embryonic day. Gain of splenic or bursal weight, natural antibodies to sheep red blood cells (SRBC), frequencies of rosette forming cells (RFC) binding to SRBC or dinitrophenyl-SRBC (DNP-SRBC) and of immunoglobulin bearing cells (IBC) in the bursa and the spleen were investigated to assess the effect of transferred cells during the embryonic stage. Transferred bursal and splenic cells showed an ability to restore the frequency of RFC or IBC in the recipients. However, reversion from the immunodeficient state was not observed in the thymic cell transfer. These findings suggested that the cells derived from embryonic bursa and spleen contained stem cells which developed into RFC and also into precursors of IBC.

Animals↗