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Biomedical subjects

S Kitayama

Publications and source records attributed to S Kitayama.

At least 109 records · Page 6Linked to original sources

A Z-DNA binding protein isolated from D. radiodurans.

A DNA binding protein isolated from D. radiodurans changes CD-spectrum of Z-form poly(dG-dC) X poly(dG-dC). We have found that a positive band at 268 nm is converted close to that of B-form in the presence of the protein. Concomitantly, a negative band at 295 nm shown by Z-form poly(dG-dC) X poly (dG-dC) was weakened by the protein but not by albumin. Such changes in the CD-spectra were not induced by the protein and by albumin when they were mixed with Z- or B-form poly(dG-me5dC) X poly(dG-me5dC) or with B-form poly(dG-dC) X poly(dG-dC). The protein formed a complex preferentially with Z-form poly(dG-dC) X poly(dG-dC).

Circular Dichroism↗

Bony mass associated with hypertrophy of the sternohyoid muscle after radical neck dissection.

As a late complication after radical neck dissection, this paper reports a bony mass at the sternal end of the clavicle associated with hypertrophy of the sternohyoid muscle. The bony mass and hypertrophy of the muscle were considered due to continuous mechanical strain by the drooping of the shoulder caused by injury of the accessory and cervical nerves, left-handed physical labour, and the lack of the sternocleidomastoid muscle in rotating the head.

Adult↗

Metabolism of two hydroxy-7-oxocholanic acids in isolated perfused rat liver.

The metabolism of 7-oxolithocholic acid and 7-oxodeoxycholic acid in isolated perfused rat livers was compared. The metabolites extracted from the bile of perfused livers were analysed by gas chromatography. The amount of bile acids excreted in bile was greater after infusion with 7-oxolithocholic acid than with 7-oxodeoxycholic acid. When 7-oxolithocholic acid was infused almost all of the bile acids excreted in bile were taurine conjugates; with 7-oxodeoxycholic acid about 10 percent remained unconjugated. 7-Oxolithocholic acid was more susceptible to reduction than 7-oxodeoxycholic acid. 7-Oxolithocholic acid was preferably reduced to 7 beta-hydroxy rather than to 7 alpha-hydroxy metabolites. In contrast, 7-oxodeoxycholic acid was reduced predominantly to the 7 alpha-hydroxy rather than to the 7 beta-hydroxy metabolite.

Animals↗

Enhancement of acetylcholine-evoked catecholamine release from perfused dog adrenals by elevating cyclic AMP levels.

Guanylyl-imidodiphosphate, guanosine 5'-tetraphosphate and phosphodiesterase inhibitors, 3-isobutyl-1-methylxanthine and RO 20-1724 significantly increased the basal cAMP output and caused a slight catecholamine (CA) release. These agents accelerated ACh-induced increase in cAMP output followed by a markedly enhanced CA release. Cholera toxin did not cause CA release but markedly enhanced ACh-evoked CA release. These results may suggest that cAMP plays a modulating role in CA release from chromaffin cells.

1-Methyl-3-isobutylxanthine↗

The nature of the stimulatory action of gamma-aminobutyric acid in the isolated perfused dog adrenals.

The effect of gamma-aminobutyric acid (GABA) on catecholamine (CA) release from adrenal medulla was investigated. GABA and GABA agonists, 3-amino-1-propane-sulfonic acid and imidazole-4-acetic acid caused CA release from isolated perfused dog adrenals in a dose-dependent manner, and no tachyphylaxis to GABA was observed. CA release elicited by GABA was antagonized by bicuculline and picrotoxin. This antagonism was specific for GABA- and GABA agonist-induced responses, response to acetylcholine being unaffected. Pretreatment with atropine plus hexamethonium did not affect the response to GABA. GABA-induced CA release was abolished by the removal of Ca2+ from perfusion medium, but not by the removal of Na+ or Cl-. Verapamil, CoCl2 and dibucaine blocked the effect of GABA. A Na+ channel blocker, tetrodotoxin did not reduce GABA-evoked CA release. These results suggest that GABA may interact with its receptor to evoke CA release from adrenal medulla in a fashion of Ca2+-dependence and independence on external Na+ or Cl-.

Acetylcholine↗

Graft-versus-host disease following allogeneic bone marrow transplantation.

Twenty-one patients, 18 with leukemia and three with severe aplastic anemia, were treated by allogeneic bone marrow transplantation. Acute graft-versus-host disease (GVHD) developed in 13 patients (62%), of whom nine (69%) had grade I, two grade II, one grade III and one grade IV. In all nine patients with grade I, elevation of the serum glutamic pyruvic transaminase level without an increase in the serum bilirubin level was observed, which suggested the presence of GVHD in the liver. All 11 patients with grade I and II responded well to therapy with predonisolone. Eleven (73%) of the 15 patients who survived for more than 100 days after marrow transplantation developed chronic GVHD. As signs of chronic GVHD, hepatic disturbances were observed in nine patients (82%), while exanthema, ophthalmic symptoms and oral mucosal symptoms were observed in seven (64%), six (55%) and four (36%), respectively. These symptoms could be well controlled by predonisolone combined with either azathioprine or cyclosporin A. Of the five deaths following the onset of chronic GVHD, three were due to interstitial pneumonitis, one to sepsis and one to relapse of the leukemia. Karnofsky's performance scores of five of the six surviving patients with chronic GVHD were 90%. Six patients with acute leukemia were still alive more than six months after marrow grafting. None of them have shown recurrence of leukemia. Five of these six had chronic GVHD.

Adolescent↗

Mutation induction by cross-links in DNA of Deinococcus radiodurans.

Reversion of adenine auxotrophic strains of D. radiodurans by cross-links in DNA was studied. Mutation was induced in a wild-type but not in a mitomycin C sensitive mutant after irradiation with near UV (approximately 365nm) in the presence of 4,5',8-trimethylpsoralen (TMP). To get information on implication of cross-links in the observed mutation, cells containing monoadducts in DNA were exposed to near UV in the absence of TMP. The mutation frequency of the wild-type increased with increasing the cross-links in DNA. These results suggest that structural defects after removal of cross-links in DNA induce mutation in D. radiodurans.

Chemical Phenomena↗

Difference between cholic acid and chenodeoxycholic acid in dependence upon cholesterol of hepatic and plasmatic sources as the precursor in rats.

Some difference in functional pool of cholesterol acting as the precursor of bile acids is pointed out between cholic acid and chenodeoxycholic acid. In order to elucidate this problem further, some experiments were performed with rats equilibrated with [7(n)-3H, 4-(14)C] cholesterol by subcutaneous implantation. The bile duct was cannulated in one series of experiments and ligated in another. After the operation 14C-specific radioactivity of serum cholesterol fell, but reached practically a new equilibrium within three days. 14C-Specific radioactivity of serum cholesterol as well as of biliary bile acids in bile-fistula rats and urinary bile acids in bile duct-ligated rats was determined during a three days-period in the new equilibrated state. The results were as follows: (1) 14C-Specific radioactivity of cholic acid and chenodeoxycholic acid in bile was lower than that of serum cholesterol, and 14C-specific radioactivity of cholic acid was clearly lower than that of chenodeoxycholic acid. (2) 14C-Specific radioactivity of cholic acid and beta-muricholic acid in urine was lower than that of serum cholesterol, and 14C-specific radioactivity of cholic acid was lower than that of beta-muricholic acid. (3) Biliary as well as urinary beta-muricholic acid lost tritium label at 7-position entirely during the course of formation from [7(n)-3H, 4-(14)C]cholesterol.

Animals↗

W-reactivation and W-mutagenesis in phage phi X 174.

W-reactivation (WR) and W-mutagenesis (WM) were observed after irradiation of phage chi X 174 with He and N ions (4.6 MeV/amu). The relative amount of phage RFI DNA (RARFI) extracted from the infected cells was determined by agarose gel electrophoresis. It was found that RARFI was increased by prior UV-irradiation of host cells and this increase corresponded to the efficiency of WR.

Bacteriophage phi X 174↗

Effect of heavy ions on bacterial spores.

Inactivation of B. subtilis spores has been studied using accelerated He, C, N, O and Ne ions. The energy dependence of the inactivation cross sections for heavy ions was very weak and the mean cross sections for carbon ions (0.6-4.7 MeV/amu), nitrogen ions (0.6-4.1 MeV/amu), oxygen ions (0.8-1.1 MeV/amu), and neon ions (2.2-3.7 MeV/amu) were found to be about 0.22, 0.23, 0.26, and 0.33 micrometer2 , respectively. Analysis was carried out along lines similar to Katz's target theory but the parameters were chosen so that they have an experimental basis.

Bacillus subtilis↗

Follicle-stimulating hormone and luteinizing hormone receptors on porcine granulosa cells during follicular maturation: an autoradiographic study.

The autoradiogram prepared from porcine ovaries after incubating for 1 hour at 37 degrees C with either 125I-labelled FSH or LH revealed that FSH bound to granulosa cells while LH bound to thecal cells. Although the granulosa cells of small, medium and large follicles were labelled with FSH, the decrease in grains over granulosa cells was observed during follicular maturation. In contrast, the granulosa cells of small and medium follicles showed only slight labelling with LH, while the granulosa cells of large follicles showed heavy labelling. The present study also indicated that granulosa cells collected from small follicles bound much more 125I-labelled FSH per cell than did cells from medium or large follicles, and granulosa cells harvested from large follicles bound much more 125I-labelled LH per cell than did cells from small or medium follicles. The competition studies with unlabelled hormones revealed that porcine granulosa cells had specific receptors for FSH and LH. The results of the present study suggest that a marked change in the binding of FSH and LH to the granulosa cells from the three follicle types might play a role in follicular growth and maturation.

Animals↗

DNA double-strand breakage and removal of cross-links in Deinococcus radiodurans.

Mitomycin C-sensitive mutants of Deinococcus radiodurans were isolated which were either resistant to or only moderately sensitive to far UV (254 nm) or gamma rays. They were also sensitive to irradiation at 365 nm in the presence of 4,5',8-trimethylpsoralen. They were classified into seven complementary groups (mtcA through mtcG) by transformation experiments. Interstrand cross-links in the DNA duplex induced by mitomycin C were removed in the cells of two mutants (mtcD and mtcE) as in the wild type, whereas the other mutants were deficient in this repair. After a sublethal dosage of mitomycin C, single- and double-stranded cuts of cross-linked DNA were observed in the wild-type cells during postincubation. This removal of cross-links in DNA seems to be indispensable for the cells since their colony-forming ability was markedly reduced if they were postincubated under an inhibitory condition for repair of these lesions.

Chloramphenicol↗

Adaptive repair of cross-links in DNA of Micrococcus radiodurans.

Cross-links in the DNA of Micrococcus radiodurans induced by mitomycin C were repaired during post-incubation. This repair process was inhibited in cells post-incubated in the presence of chloramphenicol. However, the removal of cross-links in DNA was almost normal, even in the presence of chloramphenicol, if the cells were pretreated with lower concentrations of mitomycin C.

Cross-Linking Reagents↗

Genome multiplicity and radiation resistance in Micrococcus radiodurans.

The number of genome equivalents of DNA per cell of M. radiodurans changed from approximately 5 to 10 depending on the media used. The sensitivity to ultraviolet light or gamma-rays was not different between the cells with different genome multiplicity. This suggests that the efficient repair process for DNA damage expressed in M. radiodurans is not influenced by the multiplicity of genomes in a cell.

DNA Repair↗

Mutagenicity studies on alcohol extracts from gamma-irradiated potatoes.

The alcohol extracts freshly prepared from gamma-irradiated potatoes were examined for their mutagenic activity in bacterial and mammalian cell systems. Negative results were obtained from all following test systems: Mutation assays with Salmonella typhimurium His- strains such as TA 100, TA 98, TA 1535, TA 1537, and streptomycin-dependent mutant (SMd) strain, TA 100-10, inductests with Escherichia coli strains, K 12 GY 5027 and K 12 C600, chromosomal aberration tests with Chinese hamster cells in culture, as well as micronucleus tests in mice. In addition, no difference in the mutagenic activities was found between extracts prepared from the irradiated and the unirradiated potatoes, suggesting that no mutagenic substance was produced in potatoes following gamma-irradiation.

Alcohols↗