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Biomedical subjects

H Chiba

Publications and source records attributed to H Chiba.

At least 271 records · Page 15Linked to original sources
PubMed1980

Characterization of a progestin-binding component in lactating rat mammary glands.

Experiments were carried out to identify progestin-binding receptors in the mammary gland where casein synthesis is known to be inhibited by this hormone. A progestin-binding component with high affinity, low capacity and a sedimentation coefficient of 8.8 S was isolated from the cytosol of lactating rat mammary glands. This component strongly bound [3H]R5020 (17,21-dimethyl-19-nor-4,9-pregnadiene-3,20-dione) with a dissociation constant of 3.9 . 10(-9) M under low-salt conditions and with that of 8.2 . 10(-10) M in the presence of 0.3 M KCl. Specificity studies showed a high degree of progestin specificity under high salt conditions. In the absence of KCl, binding of [3H]-R5020 was inhibited by unlabeled glucocorticoid in the same degree as unlabeled progestin, but the inhibition by glucocorticoid was greatly diminished by the presence of 0.3 M KCl. These observations suggest that the [3H]R5020-binding-component is the progestin receptor and that its function may be regulated by the concentration of glucocorticoid and salt.

Animals↗
PubMed1980

Alterations in glucocorticoid receptor conformation by molybdate.

Glucocorticoid receptor activities in cytosol from lactating rat mammary glands were greatly stabilized by molybdate against inactivation during incubation at 25 degrees C. The sedimentation coefficient was 9-10S in the presence of 10 mM Na2MoO4, but 6-7S in the absence of the ion. These data strongly suggest that alterations in receptor conformation induced by direct interaction with molybdate are involved in the stabilization process.

Animals↗
PubMed1980

Occurrence of common binding sites for progestin and glucocorticoid in the lactating mammary gland of the rat.

Previous reports have shown that in the cytosol from rat mammary gland, the high affinity binding of glucocorticoid is strongly inhibited by unlabeled progestin and that of progestin is strongly inhibited by glucocorticoid. Experiments were carried out with [3H]dexamethasone and [3H]R5020 to determine whether the binding sites for glucocorticoid and progestin are the same. Thermal inactivation experiments showed that the molecular properties of the [3H]-dexamethasone-binding sites closely resemble those of the [3H]R5020-binding sites. The dissociation constant of the [3H]R5020-receptor complex was almost exactly the same as the inhibition constant of unlabeled R5020 for [3H]dexamethasone-binding sites. The same correlation was observed between the dissociation constant and the inhibition constant of dexamethasone. In addition, no [3H]R5020-binding was observed after saturating the [3H]-dexamethasone-binding sites. These results led us to conclude that common binding sites for [3H]dexamethasone and [3H]R5020 exist in the cytosol from the rat mammary gland. The results of further experiments, including Scatchard analyses and dEAE-cellulose chromatography, strongly suggest that there are at least two classes of [3H]dexamethasone-binding sites, and that one of them binds both glucocorticoid and progestin stably.

Animals↗
PubMed1978

Changes in chromatin template activity for in vitro transcription during the development of the rat mammary gland.

The template activities of chromatin isolated from virgin, pregnant, lactating, and regressed rat mammary glands were compared by using exogenously added bacterial and mammalian RNA polymerases. Template activity increased during the stage of pregnancy, then decreased during the stage from early lactation to regression. It showed the highest level at early lactation when intracellular levels of rRNA and mRNA are known to be at their maximums. These results suggest that transcriptional activity in the mammary gland is regulated, at least in part, by a modulation of chromatin template activity.

Animals↗
PubMed1977

Essential arginyl residues in yeast phosphoglyceromutase.

Inactivation of yeast phosphoglyceromutase (tetramer) with 1,2-cyclohexanedione correlates with the modification of six arginyl residues per mole of the enzyme. Protection experiments using 3-phosphoglycerate suggest that four arginyl residues (one residue per subunit) are involved in the binding of the substrate to the enzyme. The modified enzyme reversibly regained its activity upon incubation with hydroxylamine. The reactivity of lysyl residues which have been shown to be involved in the active site is markedly reduced in the enzyme inactivated with 1,2-cyclohexanedione, indicating that the lysyl and arginyl residues are in close proximity in the active site.

Arginine↗
PubMed1977

Evaluation of the antigen specific to the mycelial phase of Candida albicans in the serodiagnosis of candidiasis.

We demonstrated 2 different antibodies against Candida albicans in patients' sera, the detection rates were proportional to the severity of candidiasis. One antibody was directed toward antigen shared by Candida in both blastospore and mycelial phases and the other was directed against antigen found only in the mycelial phase of Candida. The presence of the latter may reflect the invasive form of candidiasis.

Antibodies, Fungal↗