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Biomedical subjects

M Onoda

Publications and source records attributed to M Onoda.

At least 91 records · Page 5Linked to original sources
PubMed1986

[Studies on absorption, distribution and excretion of 14C labeled pivaloyloxymethyl (+)-(6R,7R)- 7-[(Z)-2-(2-amino-4-thiazolyl)-2-methoxyiminoacetamido]- 3-[(5-methyl-2H-tetrazol-2-yl)methyl]-8-oxo-5-thia- 1-azabicyclo[4.2.0]oct-2-ene-2-carboxylate (14C-T-2588) in rats and mice].

Absorption, distribution and excretion of T-2588 were studied in rats and mice using (aminothiazole-2-14C) T-2588 and (pivaloyloxymethyl-14C) T-2588. Results are summarized below. The binding rate of 14C-T-2525, an activated form of 14C-T-2588 in vivo, to serum protein was 90 approximately 100% in rats and mice after an oral administration of (aminothiazole-2-14C) T-2588. Blood levels of radioactivity reached to the highest concentration at 1 hour after an oral administration of (aminothiazole-2-14C) T-2588 to rats, and then gradually diminished. After an oral administration of (aminothiazole-2-14C) T-2588 to rats and mice, the highest radioactivity distribution was found in kidney among all the organs except stomach, intestine and bladder. Radioactivity was widely distributed into other organs such as adrenal, lung, liver, heart and pancreas. But little radioactivity was found in the brain. In new born rats, tissue levels of radioactivity were lower and diminished slower than those of adult rats. After an oral administration of (aminothiazole-2-14C) T-2588 to rats and mice, urinary excretion of radioactivity was about 26% and 35% of the dosed radioactivity in rats and mice, respectively, and fecal excretion was about 76% and 63% of the dosed radioactivity in rats and mice, respectively. Urinary and fecal excretion patterns of radioactivity after multiple oral administration of (aminothiazole-2-14C) T-2588 for 7 days to mice were similar to those after a single administration. This result suggests that T-2588 did not accumulate in the body. After an oral administration of (pivaloyloxymethyl-14C) T-2588 to rats and mice, urinary excretion was both about 8% of the dosed radioactivity, and fecal excretion was both about 6%. Then excretion of 14CO2 into respiratory air was about 55% and 66% of the dosed radioactivity in rats and mice, respectively. Biliary excretion was about 6.5% of the dosed radioactivity after an oral administration of (aminothiazole-2-14C) T-2588 to rats. Small amount of radioactivity was secreted to the milk after intravenous administration of (aminothiazole-2-14C) T-2525 to nursing rats. After an administration of (aminothiazole-2-14C) T-2588 to pregnant mice, radioactivity hardly transferred into the fetus.

Administration, Oral↗
PubMed1986

[The autoradiographic studies on the distribution of 14C-labeled pivaloyloxymethyl (+)-(6R,7R)- 7-[(Z)-2-(2-amino-4-thiazolyl)-2-methoxyiminoacetamido]- 3-[(5-methyl-2H-tetrazol-2-yl)methyl]-8-o xo-5-thia- 1-azabicyclo [4.2.0]oct-2-ene-2-carboxylate (14C-T-2588) in mice].

The distribution of T-2588 was studied with whole body autoradiography in normal male mice and pregnant mice using two radioactive T-2588 labeled at the aminothiazole or pivaloyloxymethyl moieties. When (aminothiazole-2-14C) T-2588 was orally administered, the radioactivity was distributed widely to whole tissues except central nervous systems such as brain and spinal cord. In pregnant mice, no detectable radioactivity was present in the fetus. These results suggested that T-2588 was well absorbed and hardly crossed the blood-brain barrier and placenta. At 4 hours after administration, radioactivity was only observed in gastrointestinal tract implying rapid excretion of T-2588. When (pivaloyloxymethyl-14C) T-2588 was orally administered, radioactivity was accumulated to all tissues and fetus. From these results we speculated that formaldehyde formed by hydrolysis at the pivaloyloxymethyl ester and entered the C1-metabolic pathway.

Administration, Oral↗
PubMed1983

Effect of various immunomodulators on the production of granulocyte/macrophage colony-stimulating factor (GM-CSF) in mouse spleen cell cultures.

Among various immunomodulating agents examined, OK-432 (Streptococcus pyogenes cell bodies), BCG (bacillus Calmette-Guerin) and LPS (lipopolysaccharide) were effective in enhancing the production of granulocyte/macrophage colony-stimulating factor (GM-CSF) in the cultures of mouse spleen cells. Control non-stimulated spleen cell cultures accumulated GM-CSF activity maximally on day 3 and lost it subsequently within a few days. On the other hand, a large amount of GM-CSF activity could be detected in the medium until day 9 when OK-432 was added in the culture at the start of incubation. The GM-CSF obtained from OK-432 or LPS stimulated cultures and the GM-CSF obtained from the control non-stimulated culture eluted from an Ultro-gel AcA 34 column at a similar position and inactivated similarly at 80 degrees C. However, these three GM-CSFs behaved in slightly different manners upon isoelectrofocusing. These results suggest that the GM-CSFs produced in increasing amounts by the stimulated spleen cells are similar to that produced by the control non-stimulated cells, but slightly different from one another in the extent of sialylation according to the difference of the stimulant.

Adjuvants, Immunologic↗
PubMed1981

Testicular microsomal cytochrome P-450 for C21 steroid side chain cleavage. Spectral and binding studies.

Kinetic and binding studies were performed with a purified microsomal cytochrome P-450 from neonatal pig testis, the C21 side chain cleavage system (17 alpha-hydroxylase/C17,20-lyase). Binding of substrates and inhibitors was measured by spectral methods and by equilibrium dialysis. Kinetic data revealed that pregnenolone inhibits lyase activity with 17 alpha-hydroxypregnenolone as substrate (Ki, 0.3 microM) and that progesterone inhibits lyase activity with 17 alpha-hydroxyprogesterone (Ki, 1.5 microM); inhibition is competitive in both cases. Binding and kinetic studies revealed that Km, Ks, and Kd (Michaelis constant and dissociation constants determined by spectral and dialysis methods, respectively) are all considerably lower for the delta 5 substrates than for the corresponding delta 4 compounds. Equilibrium dialysis shows that there is a single binding site for the substrates of both activities (hydroxylase and lyase). Spectral studies revealed a lag in the development of the spectral shift produced by the addition of steroids and gave results compatible with a single active site, although this spectral evidence is not conclusive by itself. It is concluded that (i) the powerful forward competitive inhibition by pregnenolone and progesterone may be important in regulating synthesis of androgens in vivo; (ii) the porcine enzyme uses delta 5 substrates in preference to delta 4 substrates, thereby accounting for extensive use of the delta 5 pathway by pig testis in vivo; (iii) the evidence presented suggests one active site for both hydroxylase and lyase activities.

17-alpha-Hydroxypregnenolone↗
PubMed1981

Inhibition of testicular microsomal cytochrome P-450 (17 alpha-hydroxylase/C-17,20-lyase) by estrogens.

Highly purified cytochrome P-450 from neonatal pig testicular microsomes is capable of catalyzing both 17 alpha-hydroxylation and C-17,20-lyase activity. Estradiol was found to inhibit both activities of the purified enzyme with delta 4 and with delta 5 substrates (progesterone, pregnenolone, and the corresponding 17 alpha-hydroxysteroids). For the delta 4 series, inhibition of lyase is competitive and that of 17 alpha-hydroxylase is noncompetitive; for the delta 5 series, inhibition was noncompetitive for both activities. Ki values for lyase activity were determined from enzyme kinetics (5.0 microM for the delta 4 substrate and 20 microM for the delta 5 substrate). Estradiol produces a typical type I spectral shift with the pure enzyme (Ks = 3.0 microM where Ks is the concentration of steroid required to give half maximal spectral shift), so that Ki values were also determined directly from binding studies by using substrate-induced difference spectroscopy. Fifty per cent inhibition of the maximal spectral shift induced by the 17 alpha-hydroxysubstrates (Ki) are 3.8 and 7.6 microM for the delta 4 and delta 5 substrates, respectively. Values for Ki are higher with the substrates of 17 alpha-hydroxylase (progesterone and pregnenolone), by either method, than the corresponding Ki values for the lyase substrates. The concentration of estradiol in Leydig cells of neonatal pig testis is approximately 1.5 nmol/g. It is proposed that estradiol may influence testicular steroidogensis under physiological conditions by competitive inhibition of lyase activity.

Aldehyde-Lyases↗
PubMed1980

X-ray-induced production of granulocyte-macrophage colony-stimulating factor (GM-CSF) by mouse spleen cells in culture.

Spleen cells were collected from normal mice and cultured in a medium containing 20% calf serum. Addition of lipopolysaccharide (LPS) in the culture significantly increased the production of granulocyte-macrophage colony-stimulating factor (GM-CSF), and a maximum induction was attained in 5 days. Irradiation of the spleen cells with 300 to 3,000R X-rays also enhanced the production of GM-CSF, but there was a latent period of about 5 days before the factor appeared in the culture medium. The observed difference between LPS and X-rays in the timing of inducing GM-CSF production in the spleen cell culture was consistent with the difference in timing of the increase of spleen cell proliferation observed in animals after the administration of LPS or during recovery from damages by X-irradiation. It was observed furthermore that the X-ray-induced GM-CSF differed from the LPS-induced GM-CSF in its molecular properties; the X-ray-induced factor was represented by an acidic (pI = 3.0) 70,000-dalton species, while the LPS-induced factor was much smaller in size (M.W. 20,000) and less acidic (pI = 5.4). These results suggest that different mechanisms of GM-CSF production operate in the spleen in response to either LPS or X-rays.

Animals↗
PubMed1980

Effects of various therapeutic agents on leukocytes in vivo and in vitro: competition between the cytotoxic drugs and colony stimulating factors (CSF) in the action on the proliferation of myeloid stem cells (CFU-C).

The effect of a single or repeated intraperitoneal injection(s) of various therapeutic agents on peripheral leukocyte count in mice was studied. The results revealed a great deal of initial variation of leukocyte number in the animals and also variants in the capability of the animals to restore the decreased leukocyte level. On the other hand, a simple reproducible and highly sensitive method for the evaluation of the toxic effect of the chemicals on leukopoiesis has been provided by culturing mouse bone marrow cells in a semi-solid agar medium in the presence of purified colony stimulating factor (CSF). There was three groups of chemicals in regard to the effect on the proliferation of the myeloid cells (CFU-C) in culture: (1) Anti-cancer drugs such as mitomycin C and 5-fluorouracil were inhibitory to CFU-C at 10(-8) - 10(-7)M. (2) Many drugs such as erythromycin, cephalosporin etc. showed apparent toxicity in 10(-5) - 10(-4)M. (3) Drugs like penicillin, streptomycin, cysteine etc. showed no significant toxicity at concentrations higher than 10(-4)M. It was noted that the inhibition of CFU-C proliferation either by mitomycin C (an inhibitor of DNA synthesis) or by erythromycin(an inhibitor of protein synthesis) occurred in a manner competitive to the added CSF activity. The results suggest that CSF is capable of specifically protecting the myeloid stem cells from the toxic action of the chemicals.

Animals↗