Search PubMed⌕ Search

Biomedical subjects

Y Ichikawa

Publications and source records attributed to Y Ichikawa.

At least 865 records · Page 48Linked to original sources
PubMed1976

Properties of crystalline reduced nicotinamide adenine dinucleotide phosphate-adrenodoxin reductase from bovine adrenocortical mitochonria. I. Physicochemical properties of holo- and apo-NADPH-adrenodoxin reductase and interaction between non-heme iron proteins and the reductase.

A crystalline NADPH-adrenodoxin reductase was obtained from bovine adrenocortical mitochondria and its properties were investigated. Its molecular weights and isoelectric point were estimated to be 51 000 and 5.4, respectively. Amino acid and sugar contents and the interaction between the apo-reductase and flavin of NADPH-adrenodoxin reductase were investigated. Formation of a complex of bovine NADPH-adrenodoxin reductase with adrenodoxin, its apoadrenodoxin, or other non-heme iron proteins caused quenching of fluorescence of the tryptophanyl residue and bound FAD of the NADPH-adrenodoxin reductase. The results obatined suggest that adrenodoxin and apoadrenodoxin bind functionally to a site close to the tryptophanyl residue and the bound FAD of the reductase. The circular dichroism spectrum of oxidized NADPH-adrenodoxin reductase was measured in the ultraviolet and visible regions. This spectrum showed negative absorption in the visible region and was not appreciably influenced in either the ultraviolet or visible region by formation of a complex with adrenodoxin or apoadrenodoxin.

Adrenal Cortex↗
PubMed1976

Properties of crystalline reduced nicotinamide adenine dinucleotide phosphate-adrenodoxin reductase from bovine adrenocortical mitochondria. II. Essential histidyl and cysteinyl residues at the NADPH binding site of NADPH-adrenodoxin reductase.

The binding site of NADPH in NADPH-adrenodoxin reductase was examined using crystalline enzyme from bovine adrenocortical mitochondria by studies on the effects of photooxidation and chemical modifications of amino acid residues in the reductase. (1) Photoxication decreased the enzymatic activity of NADPH-adrenodoxin reductase. Photooxidation of the reductase was prevented by NADP+, adrenodoxin, or reduced glutathione, but not NAD+. Photoinactivation caused loss of a histidyl residue, but not of tyrosyl, tryptophanyl, cysteinyl, or methionyl residues of the reductase. It did not affect the circular dichroism spectrum of the reductase appreciably. (2) NADPH-adrenodoxin reductase activity was inhibited by diethyl pyrocarbonate and the inhibition was partially reversed by addition of hydroxylamine. The inhibition was prevented by NADP+, but not NAD+. (3) NADPH-adrenodoxin reductase activity was inhibited by 5,5'-dithiobis(2-nitrobenzoate) and the inhibition was reversed by reduced glutathione. It was also protected by NADP+, but not NAD+. The results indicate that a histidyl residue and a cysteinyl residue of NADPH-adrenodoxin reductase are essential for the binding of NADPH by the reductase.

Adrenal Cortex↗
PubMed1976

In vitro differentiation of Rauscher-virus-induced myeloid leukemia cells.

Three cell lines were established in vitro from myeloid leukemias of C57Bl/6 strain mice which had been inoculated with Rauscher virus at birth. The use of heated conditioned medium from peritoneum proved helpful for the initial growth of leukemic cells. At early in vitro passage levels, cell line R433 differentiated only to macrophages after contact with conditioned medium from peritoneum but it appeared to have lost the ability to differentiate during an extended period of cultivation. Cell line R448 was cytologically promyelocyte. When exposed to conditioned medium, this cell line differentiated only to neutrophilic granulocytes. Cell line R453 maintained the ability to differentiate either to neutrophilic granylocytes or to macrophages. Single cells recloned three times still gave rise to both types of mature cells containing conditioned medium. Occasional cases of "spontaneous" differentiation in clonal lines of R453 also occurred.

Animals↗
PubMed1976

A case of unusual SLE related syndrome characterized by erythema multiforme, angioneurotic edema, marked hypocomplementemia, and Clq precipitins of the low molecular weight type.

Our patient and those of Agnello et al. had identical clinical symptoms such as erythema multiforme, arthralgias and angioneurotic edema and both differed from systemic lupus erthematosus in several important points, i.e., in spite of marked hypocomplementemia the nephropathy is not prominent and it needs high-dose steroids to eliminate the clinical and serological abnormalities. In addition to the features reported by Agnello et al. we found increased viral antibody titers in our patient's sera.

Adult↗
PubMed1976

Presence of TSH receptor in thyroid neoplasms.

The nature of the TSH receptor in adenoma and carcinoma of the thyroid gland was studied using a radioreceptor assay technique. A membrane fraction of tissue homogenate was obtained by discontinuous sucrose gradient ultracentrifugation, and 125I-TSH, labelled by a lactoperoxidase method, was purified with a receptor adsorption method. Both the capacities and the association constants of high affinity receptors (4 x 10(9) M-1) and of low affinity receptors (0.073 x 10(9) M-1) observed in the normal thyroid were almost identical to those of the thyroid of Graves' disease and those of thyroid adenoma. Although the two papillary carcinomas examined were found to have two kinds of TSH receptors, one of the carcinomas showed decreased association constants for both high affinity and low affinity receptors.

Adenoma↗
PubMed1976

Change in the mixed function oxidase system of liver microsomes in rats treated with 3'-methyl-4-dimethylaminoazobenzene.

The mixed function oxidase systems of plasma membranes, the Golgi apparatus, and smooth and rough endoplasmic reticula of the livers of rats fed on a standard diet containing 0.06% (w/w) 3'-methyl-4-dimethylaminoazobenzene were investigated. The components and activities of the mixed function oxidase systems of the smooth endoplasmic reticulum and Golgi apparatus were especially reduced by the carcinogen. The activities for hydroxylation of anilines and demethylation of p-nitroanisole and the contents of cytochromes P-450 and b5 of the submicrosomal fractions of the rats decreased considerably more than the activities of NADH- and NADPH-ferricyanide reductases. More than 90% of the ferri-cytochrome P-450 content of the 3'-methyl-4-dimethylaminoazobenzene induced microsomes at 20 K was in the low spin form.

Administration, Oral↗
PubMed1976

Studies on some lipogenic enzymes of cultured myeloid leukemic cells.

The microsomal fraction of M1 cells (an established cell line of myeloid leukemia) was capable of catalyzing acylation of sn-glycerol 3-phosphate by long-chain fatty acyl-CoA thioesters. The principal lipid product formed was identified as phosphatidic acid. Palmityl-CoA, stearyl-CoA, and oleyl-CoA were more effective acyl donors than linoleyl-CoA and arachidonyl-CoA. M1 cells and macrophages differentiated from them exhibited similar levels of sn-glycerol 3-phosphate-acylating activity, which were approximately one-half that in mouse liver and approximately four times that in peritoneal macrophages. The levels of acetyl-CoA carboxylase activity in M1 cells and macrophages differentiated from them were not significantly different from each other and were comparable to those in mouse liver, whereas no activity was detected in peritoneal macrophages. These results indicated that differentiation of the myeloid leukemic cells, which results in loss of leukemogenicity and mitotic activity, is not associated with changes in the activities of these lipogenic enzymes, although the cultured cells exhibited remarkably higher activities than freshly harvested peritoneal macrophages. Furthermore, the present study supports the view that the glycerophosphate pathway makes an essential contribution to the de novo synthesis of phospholipids in M1 cells, as well as in both types of macrophages.

Acetyl-CoA Carboxylase↗
PubMed1975

Distribution of NAD(P)H-dependent cytochrome P-450 mixed function oxidase system in the brush border membrane of rabbit kidney cortex.

Optical and magnetic studies were made on subfractions of rabbit kidney cortex. Cytochrome P-450 and cytochrome b5-dependent mixed function oxidase systems were localized mainly in the brush border membranes and microsomes. Cytochrome P-450-dependent mixed function oxidases in the membranes comprised both an NADPH-dependent system and an NADH-dependent system.

Animals↗