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Biomedical subjects

M Ohashi

Publications and source records attributed to M Ohashi.

At least 451 records · Page 25Linked to original sources
PubMed1983

Contributions of cytoplasmic free and membrane-bound ribosomes to the synthesis of NADPH-adrenodoxin reductase and adrenodoxin of bovine adrenal cortex mitochondria.

Cytoplasmic free and membrane-bound ribosomes were isolated from bovine adrenal cortex, and characterized. Contributions of free and bound ribosomes to the synthesis of NADPH-adrenodoxin reductase (AdR) and adrenodoxin (Ad) were determined by examining the presence of their nascent peptides on isolated ribosomes. Nascent peptides were released from the ribosomes by [3H]puromycin in a high salt buffer in the presence of a detergent, and the nascent peptides of AdR and Ad were separately isolated by immunoprecipitation using antibodies. AdR nascent peptides were associated with free and loosely-bound ribosomes, whereas Ad nascent peptides were associated with free, loosely-bound and tightly-bound ribosomes. Smaller nascent peptides of AdR were carried by free ribosomes, whereas larger nascent peptides were preferentially carried by loosely-bound ribosomes. In the case of Ad, smaller nascent peptides were more abundant in free ribosomes than in bound ribosomes. The nascent peptides of Ad were released from bound ribosomes of rough microsomes to the aqueous milieu by puromycin treatment, suggesting the release of completed Ad peptides into the cytoplasm in cells.

Adrenal Cortex↗
PubMed1983

Effective extraction and radioimmunoassay of chorionic gonadotropin in human urine.

A single-step procedure for extracting and concentrating hCG from 24hr urine samples was developed. The procedure involves the adsorption chromatography with Vitachange (Permutit). Its hCG recovery was improved to be more than 90% compared with about 50% of a standard kaolin-acetone method. Nonspecific urinary protein concentration in extracts was also reduced. Thus, partial purification and concentration of urinary hCG by this procedure with subsequent RIA using antisera against the unique carboxyl-terminal peptide of hCG beta subunit provides a sensitive and specific method for detecting hCG in urine. In urine samples obtained from normal persons, the upper limit of hCG-immunoreactivity detected by this new system was 1.1 IU/24hr. However, 93% of subjects gave values lower than 0.5 IU/24hr. The urinary hCG level of lower than 1.1 IU/24hr may be designated as normal. This new assay system now provides reliable potentiality in the strict management of patients who are undergoing treatment for gestational trophoblastic neoplasia.

Chorionic Gonadotropin↗
PubMed1982

Low density lipoprotein receptors in adrenal tissue of a human anencephalic fetus.

The binding of [125I]iodoLDL and [125I]iodoHDL to membrane fractions prepared from fresh adrenal tissue of an anencephalic newborn was examined and compared to the binding of these lipoproteins to membrane fractions prepared from normal human fetal adrenal (HFA) tissue. The apparent dissociation constant (KD) for the interaction of [125I]iodoLDL with its binding sites in membrane fractions prepared from HFA tissue of an anencephalic fetus (23.5 micrograms . ml-1) was similar to that in membranes from normal HFA tissue. However, the binding capacity for [125I]iodoLDL of membrane fractions prepared from adrenal tissue of an anencephalic fetus (600 ng . mg-1 protein) was only one-third of the binding capacity (1500 ng . mg-1 protein) of normal HFA membrane fractions. On the other hand, the binding capacity for [125I]iodoHDL of membrane fractions prepared from anencephalic and normal adrenal tissue was similar.

Adrenal Glands↗
PubMed1982

Serological comparison of two collections of Vibrio cholerae non O1.

Two large, independently obtained collections of vibrio cholerae non O1, containing 59 and 67 reference strains, respectively, were compared serologically in four laboratories. Twenty strains in each collection were considered identical, and an additional 16 strains in each collection were probably identical. Twenty-eight unique strains were identified, and inconclusive results were obtained with 25 strains. Nine strains were not considered V. cholerae in at least one testing laboratory. Of these, five showed insufficient correspondence to V. cholerae O1 by DNA hybridization to be considered V. cholerae.

Agglutination Tests↗
PubMed1982

Lipoprotein-binding sites in human corpus luteum membrane fractions.

In a previous report evidence was presented that plasma low density lipoprotein (LDL), but not high density lipoprotein (HDL), is the major source of cholesterol used by the human corpus luteum for progesterone biosynthesis and, that plasma LDL is taken up by corpus luteum tissues via a receptor-mediated endocytotic process. Using membrane fractions prepared from fresh corpus luteum tissue obtained from nine women at various phases of the menstrual cycle, we conducted the present investigation to characterize lipoprotein-binding sites and changes in such binding sites that might occur throughout the ovarian cycle. High affinity, low capacity binding sites for [125I]iodo-LDL and also for [125I]iodo-HDL were detected in membrane fractions prepared from fresh corpus luteum tissue. The interaction of [125I]iodo-LDL with the high affinity binding sites in fresh corpus luteum membrane fractions was prevented by incubation with heparin. Also, the binding capacity of corpus luteum membrane fractions for [125I]iodo-LDL was reduced by treatment with pronase. On the other hand, the specific binding capacity for [125I]iodo-HDL was unaffected by pronase treatment. The binding capacity for [125I]iodo-LDL in membrane fractions prepared from midluteal phase corpus luteum was significantly greater than that of membrane fractions from tissue obtained at any other phase of the cycle, a finding that suggests that changes in progesterone biosynthesis throughout the cycle are positively correlated with changes in the numbers of binding sites for LDL in the corpus luteum.

Adult↗
PubMed1982

Low density lipoprotein binding and de novo synthesis of cholesterol in the neocortex and fetal zones of the human fetal adrenal gland.

The binding of low density lipoprotein (LDL) and the de novo synthesis of cholesterol in separated zones of human fetal adrenal (HFA) tissues were investigated. The number of LDL-binding sites was 2-fold greater in membrane fractions prepared from fresh fetal zone tissue than in those from neocortex tissue. The binding capacity for LDL in fetal zone and neocortex membrane preparations of HFA tissues maintained in culture in the presence of ACTH was 2-fold greater than that in membrane fractions of control tissues. The rates of de novo synthesis of cholesterol also were determined in separated zones of HFA tissue by measuring the specific activity of 3-hydroxy-3-methylglutaryl coenzyme A reductase in microsomal fractions prepared from HFA tissues and by determining the rate of incorporation of tritium from [3H]water into cholesterol in HFA tissue fragments. The rate of de novo synthesis of cholesterol in fresh fetal zone tissue was twice that in neocortex tissue as estimated by these methods. When separated zones of HFA tissue were maintained in culture in the presence or absence of ACTH, the rates of de novo synthesis, as determined by the rate of incorporation of tritium from [3H]water into cholesterol, were stimulated to a similar extent by ACTH in both fetal zone and neocortex tissues. However, the specific activity of 3-hydroxy-3-methylglutaryl coenzyme A reductase was increased to a greater extent by ACTH pretreatment in neocortex tissues than in fetal zone tissues. In summary, fetal zone tissues of the HFA gland have a larger number of LDL-binding sites and higher rates of de novo synthesis of cholesterol than do neocortex tissues, and ACTH stimulates LDL binding and de novo synthesis of cholesterol in both zones of the HFA gland.

Adrenal Cortex↗
PubMed1982

The binding of high and low density lipoproteins to human placental membrane fractions.

It was shown previously that human placental trophoblastic cells use principally lipoprotein cholesterol for progesterone biosynthesis and that the rate of de novo synthesis of cholesterol is low. In addition, it was demonstrated that cholesterol derived from maternal plasma low density lipoprotein (LDL) rather than high density lipoprotein (HDL), is the principal source of placental cholesterol. In the present investigation, membrane fractions derived from human placenta were used to identify and characterize specific binding sites for both HDL and LDL. Pretreatment of membrane fractions with heparin resulted in an increase in the specific binding capacity for [125I]iodo-LDL 1.5 times that in membrane fractions not pretreated with heparin. Heparin pretreatment did not affect significantly the specific binding capacity of placental membranes for [125I]iodo-HDL. The specific binding capacity for [125I]iodo-LDL was 107 ng LDL protein mg-1 membrane protein, with an approximate Kd of 77 microgram LDL protein ml-1 in membranes pretreated with heparin. The specific binding capacity for [125I]iodo-HDL was much greater, equal to 323 ng HDL protein mg-1 membrane protein, with an approximate Kd of 152 microgram HDL protein ml-1. Each [125I]iodolipoprotein was specifically displaced by the corresponding respective nonradiolabeled lipoprotein. Preincubation of membranes with trypsin and pronase caused reductions in the specific binding capacity for [125I]iodo-LDL of 88% and 100%, respectively. Incubation of membranes with heparin caused displacement of [125I]iodo-LDL. However none of these treatments affected [125I]iodo-LDL. However none of these treatments affected [125I]iodo-HDL binding capacity. Similar binding sites for "125I]iodo-LDL and [125I]iodo-HDL were demonstrated in cells prepared from human placenta by trypsin digestion and maintained in monolayer culture.

Binding Sites↗