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Biomedical subjects

H Oda

Publications and source records attributed to H Oda.

At least 505 records · Page 28Linked to original sources
PubMed1981

Isolation and characterization of thirteen intestinal microorganisms capable of 7 alpha-dehydroxylating bile acids.

Thirteen anaerobic bacteria capable of performing the 7 alpha-dehydroxylation of both cholic acid and chenodeoxycholic acid were isolated from human feces and also from sewage. Ten organisms from heat-treated samples were species of Clostridium identical or closely related to the Clostridium bifermentans-C. sordellii group and consisted of four strains elaborating 7 alpha-dehydroxylase alone and six strains capable of catalyzing both 7 alpha-dehydrogenation and 7 alpha-dehydroxylation. The remaining three organisms, recovered from fresh human feces, were gram-positive, nonflagellated, nonsporeforming, anaerobic rods and comprised two distinct species. Strain HD-17, still unidentified, had both activities, but was unique in that it exclusively 7 alpha-dehydroxylated cholic acid while biotransforming chenodeoxycholic acid, preferably though 7 alpha-dehydrogenation. Two unclassified strains, b-8 and c-25, metabolized both acids though 7 alpha-dehydroxylation and 7 alpha-dehydrogenation. Except for strains b-8 and c-25, all of th 7 alpha-dehydroxylating bacteria split the conjugated bile acid series, and hydrolases were detected in cell-free filtrates of early stationary-phase broth cultures.

Bacteria↗
PubMed1981

Transformation of bile acids by Clostridium perfringens.

Thirty-five strains of Clostridium perfringens were examined for their ability to transform bile acids, both in growing cultures and by washed whole cells. All of the strains oxidized the 3 alpha-hydroxy group to an oxo group, and all except three converted the same alpha-hydroxy group into a beta-configuration. The oxidative 3 alpha-dehydrogenation was barely detectable under anaerobic cultural conditions but was clearly demonstrated in an aerated system using washed whole cells, with a pH optimum between 7.0 and 9.0. The epimerizing reaction amounting to 10 to 20% conversion was observed in anaerobic cultures and also with resting cells, irrespective of oxygen supply. Both reactions were carried out with seven conventional 3 alpha-hydroxy bile acids, thus producing a series of 3-oxo and 3 beta-hydroxy derivatives that could be examined for gas-liquid chromatographic and mass spectrometric behavior. No evidence for the occurrence of 7 alpha- and 12 alpha-hydroxysteroid dehydrogenase activities among the test strains was found. A highly potent deconjugating hydrolase was elaborated by all of the strains.

Aerobiosis↗
PubMed1981

In vitro transformation of chenodeoxycholic acid and ursodeoxycholic acid by human intestinal flora, with particular reference to the mutual conversion between the two bile acids.

Nine fecal samples from four healthy subjects were examined for their ability to transform chenodeoxy-cholic acid (CDCA) and ursodeoxycholic acid (UDCA) in in vitro anaerobic broth cultures. Seven samples converted CDCA and UDCA into each other (more than 50% of CDCA was converted into UDCA while 10% or less of UDCA was converted into CDCA), and produced 7-keto-lithocholic acid and lithocholic acid equally from both acids. No alteration of the 7 beta-hydroxy group of UDCA was demonstrated by two fecal samples that failed to perform mutual 7-epimerization, suggesting the conversion of UDCA into lithocholic acid via CDCA. The 3 alpha-hydroxy groups of these substrate and metabolite bile acids were invariably partially epimerized to 3 beta-hydroxy groups by all the fecal samples. Evidence is presented for the prevalence of these 7- and 3-epimerizing organisms among the human intestinal flora.

Adult↗
PubMed1980

Tubular structures in the cervix of mice experimentally infected with herpes simplex virus type 2.

Experimental infection of the C3H/N mouse genital tract was demonstrated after intravaginal inoculation with herpes simplex virus type 2 (HSV-2). About 75% of the infected animals died by Day 7, and 75% of the surviving animals had severe vaginitis or neurological signs on Day 7. Titers of the virus recovered from vaginal secretions of infected animals reached a maximum on Day 2 and gradually decreased until Day 7. On the other hand, under the electron microscope, virus particles and tubular structures could be found in the nuclei of infected cells of the cervix in the 1st, 2nd and 4th days after infection. All cases in which virus particles could be found in the nuclei of infected cells were also positive for tubular structures and vice versa. These observations indicate that in situ diagnosis of HSV-2 infection can be made in the mouse model. The same method would be applicable for the diagnosis of human HSV-2 infection.

Animals↗
PubMed1980

Reaction of hemoglobin with nitric oxide and nitrogen dioxide in mice.

The reaction of hemoglobin with NO and NO2 was compared in mice exposed to these cases. Nitrosyl hemoglobin (NOHb) and methemoglobin (MetHb) were determined simultaneously by electron spin resonance spectrometry at -140 degrees C. In mice exposed to 40 ppm NO, NOHb became constant (0.7%) in 30 min and declined rapidly with a half-life of several minutes when the mice were removed to room air. An increase of MetHb (5%) was also caused by exposure to NO and the time course was almost the same as that of NOHb. Exposure to 40 ppm NO2 produced only NOHb (0.2%); MetHb did not increase. The time course of NOHb was identical to that observed with NO exposure. Dose-effect relationships were determined with both gases at concentrations ranging from 20 to 80 ppm. A linear relationship could be observed between the concentrations of the gases and NOHb, but NO produced more NOHb than did NO2. There was an exponential increase of MetHb, particularly at high concentrations of NO.

Animals↗
PubMed1979

Effects of antimetabolites on the production of tubular structures in Vero cells infected with herpes simplex virus type 2.

Treatment of Vero cells infected with herpes simplex virus type 2 with the proper concentrations of hydroxyurea (HU) reduced the production of infectious virus and markedly increased the accumulation of tubular structures in the nuclei when the drug was added within 6 hours after infection. Similar accumulation of tubular structures in the infected nuclei was also observed when infected cells were treated with phosphonoacetic acid at proper concentrations. The release of HU-treated, herpes simplex virus type 2-infected cells from the drug-induced blocking of synthesis of infectious virus resulted in the marked decrease of tubular structures coincidentally with the beginning of production of infectious virus. The data suggest the possibility that the disappearance of tubular structures may be related to the active production of infectious virus.

Animals↗
PubMed1979

Production of tubular structures in Vero cells infected with herpes simplex virus type 2; effects of ultraviolet light irradiation and antimetabolites.

In order to investigate the nature of tubular structures specifically found in herpes simplex virus type 2 (HSV-2)-infected cells, the multiplication of HSV-2 was studied in Vero cells cultured in the presence of varying concentrations of cytosine arabinoside (Ara-C) and cycloheximide (CH), inhibitors of DNA synthesis and protein synthesis respectively. Ara-C, at a concentration of 60 micrograms/ml, inhibited the multiplication of HSV-2 by more than 99% and also prevented the appearance of tubular structures and virus particles in the nuclei of infected cells. Nevertheless, the synthesis of virus specific surface antigens of HSV-2-infected Vero cells was not reduced, as revealed by the fluorescent antibody technique. On the other hand, 10 micrograms/ml of CH inhibited both the appearance of tubular structures and virus particles and the synthesis of virus specific surface antigens by more than 99%. These observations strongly suggest that the appearance of tubular structures is one of the late events in the process of virus multiplication. To measure the comparative genome size needed to produce membrane antigens, tubular structures and infectious centres, the effect of u.v.-inactivation of HSV-2 on these processes was studied. After u.v.-irradiation, the capacity to induce tubular structures was inactivated at a slower rate than the capacity to form infectious centres, but at a faster rate than the induction of surface antigens. Furthermore, more tubular structures could be induced by u.v.-inactivated virus than by the non-irradiated virus which was diluted to the same infectivity as the u.v.-irradiated virus. These results indicate that expression of the entire genome is not required for the production of tubular structures.

Animals↗