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Biomedical subjects

K Ohshima

Publications and source records attributed to K Ohshima.

At least 397 records · Page 22Linked to original sources
PubMed1986

Cyclo (His-Pro), a metabolite of thyrotropin-releasing hormone: specific binding to rat liver membranes.

[3H]cyclo(His-Pro) bound with high affinity (59 nM) to a single class of sites in rat liver plasma membranes, without significant tracer degradation during equilibration for 60 min at 0 degrees C. Binding was specific and saturable (3.9 pmol/mg protein), and were increased by the addition of K+, Mg++ and Na+ at optimal concentrations, but not of Ca++ at all concentrations tested. In vivo administration of cyclo(His-Pro), but not thyrotropin-releasing hormone, to rats caused the downregulation of cyclo(His-Pro)-binding sites with decreases in specific binding numbers but did not change binding affinity.

Animals↗
PubMed1986

Effect of adrenalectomy on the pancreas of db/db mice.

Adrenalectomy has been performed in the diabetic mouse and the islet immunohistochemistry studied. Adrenalectomy restored blood glucose to normal. Mean islet size of diabetic animals was larger than that of either adrenalectomized diabetic animals or of lean controls. Adrenalectomy restored the immunohistochemical appearance of the islets to normal when examined with anti-insulin, anti-glucagon and anti-somatostatin antisera.

Adrenalectomy↗
PubMed1986

An insertion mutation in the adenovirus type 12 early region 1A 13S mRNA unique region.

An adenovirus type 12 mutant, in203S, was constructed to contain an insertion of two amino acids in the early region 1A (E1A) 13S mRNA-coding region and in the E1A 12S mRNA intron. in203S could not grow in HeLa and KB cells. Virus DNA replication was scarcely detected at a low multiplicity of infection, but was detected at a high multiplicity of infection. The transcription of early genes other than E1A was not detected at 13 h after infection, but became detectable after longer incubation. The transcription of the E1A gene was also reduced to about one-fifth of the wild-type level. The mutant induced fewer foci of smaller sizes than the wild type in rat 3Y1 and secondary rat kidney cells. The induction of cellular DNA synthesis was reduced in rat 3Y1 cells infected with in203S as compared with that in wild type-infected cells. These results show that the E1A 13S mRNA-derived polypeptide of adenovirus type 12 is required for activation of early genes, cell transformation, and induction of cellular DNA synthesis.

Adenovirus Early Proteins↗
PubMed1986

The adenovirus type 12 early-region 1B 58,000-Mr gene product is required for viral DNA synthesis and for initiation of cell transformation.

An E1B 58K mutant of adenovirus type 12 (Ad12), dl207, was constructed by the deletion of 852 base pairs in the E1B 58K coding region. The mutant could grow efficiently in 293E1 cells but not in HeLa, KB, or human embryo kidney (HEK) cells. Viral DNA replication of dl207 was not detected in HeLa and KB cells and was seldom detected in HEK cells. Analysis of viral DNA synthesis in vitro showed that the Ad12-DNA-protein complex replicated by using the nuclear extract from Ad12 wild-type (WT)-infected HeLa cells but not by using the nuclear extract from dl207-infected cells. In dl207-infected HeLa and KB cells, early mRNAs were detected, but late mRNAs were not detected. The mutant induced fewer transformed foci than the WT in rat 3Y1 cells. Cells transformed by dl207 could grow efficiently in fluid medium, form colonies in soft agar culture, and induce tumors in rats transplanted with the transformed cells at the same efficiency as WT-transformed cells. Tumors were induced in hamsters injected with WT virions but were not induced in hamsters injected with dl207 virions. The results indicate that the E1B 58K protein is required both for viral DNA replication in productive infection and for initiation of cell transformation, but not for maintenance of the transformed phenotype.

Adenovirus Early Proteins↗
PubMed1985

Usefulness of monoclonal antibodies for detection of enzootic bovine leukemia cells.

Monoclonal antibodies against tumor-associated antigens (TAAs) expressed in the leukemic cells of enzootic bovine leukosis (EBL) were examined for their possible usefulness in detecting EBL tumor cells. The antibodies immunohistochemically reacted with EBL tumor cells and had cytotoxic activity against the cells but not against normal adult bovine peripheral blood lymphocytes (PBL) even after activation with mitogens. The TAA-positive EBL tumor cells also had B cell surface markers. The TAA was also found in several samples of PBL taken from BLV-infected healthy cattle (8 positive out of 81 tested), as well as in PBL from 13 out of 14 cattle with lymphocytosis but no evidence of tumor. Thus, monoclonal antibodies directed against TAAs might be a useful tool not only for diagnosing EBL but also for screening of BLV-infected cattle with the potential to develop tumors in the future.

Animals↗
PubMed1984

Adrenalectomy increases norepinephrine turnover in brown adipose tissue of obese (ob/ob) mice.

The hyperphagia and rapid body weight gain normally observed in young obese (ob/ob) mice were abolished by removal of their adrenal glands, whereas food intake and weight gain of lean mice were not significantly affected by adrenalectomy. Adrenalectomy lowered body energy density (kcal/g carcass) in obese mice more than could be attributed to reduced food intake per se, suggesting that their energy expenditure was also increased. In control obese mice, low stimulation of brown adipose tissue by the sympathetic nervous system, as indicated by the low fractional rates of norepinephrine (NE) turnover in their brown adipose tissue may have contributed to the reduced energy expenditure in these animals. Adrenalectomy increased the rates of NE turnover in brown adipose tissue of obese mice to rates nearly equal to those observed in lean mice without affecting NE turnover in this tissue of lean mice. Likewise, removal of the adrenals normalized the low rates of NE turnover in hearts of obese mice without affecting lean mice. Rates of NE turnover in two other organs, white adipose tissue and pancreas, of control and adrenalectomized obese mice were similar to rates observed in lean counterparts. The adrenal may thus contribute to both the hyperphagia and the low energy expenditure by brown adipose tissue that together cause gross obesity in ob/ob mice.

Adipose Tissue, Brown↗
PubMed1984

The relationship between lethal mutation yield and intake of ethylnitrosourea (ENU) in Drosophila melanogaster.

To estimate the absorbed dose of N-ethyl-N-nitrosourea (ENU) ingested in Drosophila melanogaster, males were fed with sucrose solutions containing various concentrations of ENU plus 3H-labeled sucrose for 24 hr. Flies showed decreasing intakes with increase in ENU concentration when monitored by intake 3H radioactivity. Absorbed dose, D, per male can be estimated by the following formula: D = v . C, where v is intake volume per male of sucrose solution at concentration C. Estimating the v value for each ENU solution from 3H radioactivities in male flies, and using the above formula, we reached the conclusion that average absorbed doses of ENU were 0.064, 0.221, and 0.302 nmol, respectively, for the ENU concentrations of 0.03, 0.3, and 1.0 mM. Sex-linked recessive lethals were measured for males exposed to these sucrose solutions at three different ENU concentrations. Their frequencies increased nonlinearly with increasing exposure doses--ie, ENU concentration C--but linearly with increasing absorbed doses estimated in the above-mentioned way.

Animals↗
PubMed1984

Comparative studies of dose-response curves for recessive lethal mutations induced by ethylnitrosourea in spermatogonia and in spermatozoa of Drosophila melanogaster.

Induction of recessive lethal mutations by N-ethyl-N-nitrosourea (ENU) was studied for the second chromosome of spermatogonia and spermatozoa in Drosophila melanogaster. ENU (0.03, 0.3, and 1.0 mM) was given to flies by dissolving it in feeding sucrose solution. Since flies are known to show increased avoidance of the feeding solution with increase in ENU concentration, the absorbed doses of ENU by flies were estimated from the previously determined empirical data for relation of ENU concentration in the feeding solution and the intake volumes of the solution by flies as measured indirectly via intake radioactivities of 3H-labeled sucrose added to the solution. When plotted against absorbed doses of ENU, the observed frequencies of recessive lethals showed a linear relationship for induction in spermatozoa but a sigmoidal relationship for induction in spermatogonia. These results suggest that in spermatogonia ENU-induced mutational damage is more repairable in a lower dose range of ENU. Mosaic lethal mutations were induced by ENU but not in spermatogonia.

Animals↗
PubMed1984

Adrenalectomy reverses insulin resistance in muscle from obese (ob/ob) mice.

Glucose transport and insulin resistance in the skeletal muscle of the genetically obese (ob/ob) mouse has been studied in animals at 6-7 wk of age using an in situ perfused hindquarter preparation. Rates of glucose uptake and the uptake of radioactively labeled 2-deoxy-D-glucose were lower in muscles from intact ob/ob mice than in those from their lean littermates. Following adrenalectomy the basal rate of glucose or 2-deoxy-D-glucose uptake in the ob/ob mice was restored to normal. The uptake of 2-deoxyglucose was tested at two insulin concentrations. In lean mice, adrenalectomy had no effect on 2-deoxyglucose uptake. Adrenalectomy, however, restored the responsiveness to insulin in the ob/ob mouse to normal. The activity ratio of muscle glycogen synthase was elevated by insulin but the effect was greater in the lean animals with or without adrenal glands than in the obese mouse. Adrenalectomy in the obese mouse did not correct this defect.

Adrenal Glands↗