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T Oda

Publications and source records attributed to T Oda.

At least 541 records · Page 30Linked to original sources
PubMed1989

Direct inhibitory ovarian effects of prolactin in the process of ovulation.

The present study was designed to determine the effects of prolactin (PRL) on the process of follicle rupture and oocyte maturation using an in vitro perfused rabbit ovary model. In the first experiment ovaries were perfused for 12 hours with or without PRL at 10(2) or 10(3) ng/ml. Ovulation did not occur in any ovaries in the absence of gonadotropin. The majority of follicular oocytes did not progress beyond the germinal vesicle stage following treatment with PRL. The percentage of follicular oocytes which showed evidence of degeneration was also comparable in both groups. The concentrations of progesterone in the perfusate did not differ significantly between PRL-treated and control ovaries. In the second experiment, ovaries were perfused with or without PRL at 10, 10(2), or 10(3) ng/ml. Thirty minutes later 50 IU of human chorionic gonadotropin (hCG) was added to the perfusate of all ovaries. The addition of PRL to the perfusate inhibited hCG-induced ovulation in a dose-related fashion. The degree of ovum maturity and degeneration was comparable in the two groups. PRL did not affect hCG-stimulated progesterone production by the perfused rabbit ovaries. The present study demonstrates that PRL acts directly on the ovary to influence the process of ovulation, resulting in the inhibition of hCG-induced follicle rupture. These data suggest that PRL inhibits ovulation by mechanism(s) independent of ovarian progesterone synthesis.

Animals↗
PubMed1988

Isolation of protein kinase C subspecies from a preparation of human T lymphocytes.

Using a preparation of purified human T lymphocytes, we were able to resolve a partially purified protein kinase C (PKC) enzyme fraction into two distinct subspecies, of approximately equal activity. Biochemical and immunocytochemical analysis revealed that these fractions closely resembled the type II (beta) and type III(alpha) PKC subspecies previously identified and characterised from brain tissue. These results provide valuable information for further studies on the role of individual PKC subspecies in T lymphocyte proliferation.

Calcium Chloride↗
PubMed1988

Effects of chronic treatment with a novel angiotensin converting enzyme inhibitor, CS622, and a vasodilator, hydralazine, on atrial natriuretic factor (ANF) in spontaneously hypertensive rats (SHR).

We studied the effects of chronic treatment with a novel angiotensin converting enzyme inhibitor, alpha-[(2S,6R)-6-[(1S)-1-ethoxycarbonyl-3-phenylpropyl]amino-5-oxo-2- (2-thienyl)perhydro-1,4-thiazepin-4-yl]acetic acid.HCl (CS622), and a vasodilator, hydralazine, on plasma atrial natriuretic factor (ANF) levels and kidney ANF receptors in spontaneously hypertensive rats (SHR). Plasma ANF level was decreased and cardiac hypertrophy reduced in CS622 treated SHR, but not in hydralazine treated SHR, although blood pressure was lowered similarly in both SHR groups. The binding capacity of kidney ANF receptors increased and the affinity decreased in CS622 treated SHR compared to untreated SHR. These results suggest that decrease of plasma ANF results from decreased cardiac load but not from lowered blood pressure, and that changes in ANF receptors result from increased plasma ANF.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1988

Effect of an anti-ulcer drug, plaunotol, and its metabolites on NAD+ dependent 15-hydroxyprostaglandin dehydrogenase from gastric mucosa.

15-Hydroxyprostaglandin dehydrogenase was partially purified from hog gastric mucosa by about 1000-fold with a 13.5% yield. Its molecular weight was estimated to be 32,000 daltons by gel filtration. The enzyme was inhibited by some metabolites of plaunotol [(2E, 6Z, 10E)-7-hydroxymethyl-3,11,15-trimethyl-2,6,10,14-hexadecatetrae n-1- ol], a new anti-ulcer drug. The inhibition patterns for substrates, prostaglandin E1 and NAD+ were both uncompetitive with Ki values of 7.8 and 19.7 microM, respectively.

Animals↗
PubMed1988

An exonuclease possibly involved in the initiation of repair of bleomycin-damaged DNA in mouse ascites sarcoma cells.

A protein factor having exonucleolytic activity on bleomycin-damaged DNA and providing priming sites for DNA polymerases existed in a DNA polymerase beta fraction partially purified by ion exchange chromatography from an extract of permeable mouse ascites sarcoma (SR-C3H/He) cells. The exonuclease was separated from DNA polymerase beta by single-stranded DNA-cellulose chromatography, and partially characterized. The enzyme is suggested to be involved in the initial step of repair of bleomycin-damaged DNA in removing 3' ends (3'-phosphoglycolate termini) of bleomycin-damaged DNA.

Animals↗
PubMed1988

Chemical modification of tryptophanase by chloramine T: a possible involvement of the methionine residue in enzyme activity.

Tryptophanase purified from Escherichia coli B/1t7-A was irreversibly inactivated by chloramine T (sodium N-chloro-p-toluenesulfonamide). The mode of inactivation was rather complex and did not follow pseudo-first-order kinetics. The inactivation of the apoenzyme was much faster than that of the holoenzyme. The Km value for the synthetic substrate S-o-nitrophenyl-L-cysteine (SOPC) increased concomitantly with the modification. In contrast, the Km value for the coenzyme, pyridoxal 5'-phosphate (PLP), was not altered. L-Serine, another substrate, and L-alanine, a competitive inhibitor, protected the enzyme from inactivation. Determination of SH groups in the enzyme protein with 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB) showed that modification of two SH groups per enzyme subunit resulted in a complete inactivation. When the enzyme was subjected to chloramine T-modification following the SH group modification with DTNB, further inactivation was still observed, even after the addition of dithiothreitol. The SH-blocked enzyme preparation thus obtained, however, exhibited less pH dependency of inactivation by chloramine T than that of the native enzyme. The amino acid analysis of the chloramine T-modified enzyme showed that modification of four or five methionine residues among the 16 residues per subunit proceeded concomitantly with the complete inactivation. Modification of the enzyme with chloramine T quenched the absorption peak near 500 nm, characteristic of a quinoidal structure formed by labilization of the alpha-proton. These results suggest the possibility that chloramine T modifies not only the SH groups, but also methionine residues important for the catalytic activity of the enzyme.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1988

Cardiovascular pharmacology of RS-1893, an orally active cardiotonic agent with arterial and venous vasodilator actions.

RS-1893, 2-[2-chloro-4-(2,3,4,5-tetrahydro-3-oxo-6-pyridazinyl)]-phenoxy-N- (2-(2-morpholinoethyl)-acetamide, is a newly synthesized compound whose structure is different from that of cardiac glycosides and beta-stimulants. The in vitro cardiotonic action of RS-1893 was about 3 times more potent than that of milrinone. This action is most likely due to inhibition of phosphodiesterase-III, as has been suggested for many other cardiotonic agents. In pentobarbital anesthetized dogs, RS-1893 (1-30 micrograms/kg, i.v.) produced dose dependent increases in left ventricular dP/dtmax and cardiac output and caused decreases in blood pressure and total peripheral resistance with a relatively small increase in heart rate. Central venous pressure decreased markedly, suggesting venous vasodilation. The in vivo cardiotonic action of RS-1893 was 3 times more potent than that of milrinone and was not affected in the presence of a large dose of propranolol. Oral administration of RS-1893 (0.03 and 0.1 mg/kg) also produced a dose-related increase in cardiac contractility in conscious beagles. The increase in LVdP/dtmax reached a maximum in 1-3 hr after administration and lasted for more than 8 hr. Thus, RS-1893 appeared to be an orally active cardiotonic agent with vasodilator properties, probably acting on both arterioles and veins.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1988

[Studies involving 11 cases of early gastric cancer with a widespread lymph node metastasis].

Over the past 10 years, we have experienced 11 cases of early gastric cancer limited to the mucosa and submucosa, with a widespread lymph node metastasis over the perigastric node. These cases represented 3.8% of all the early gastric cancer cases treated at our hospital during this period. The average age of these patients was 49.1 years, and consisted of 7 males and 4 females. Of these 11 cases, 10 cases (90.9%) were, macroscopically, the depressed type. Histologically, 7 cases (63.6%) were poorly differentiated carcinoma. Curative resections were possible in 8 cases (72.7%). The cumulative 5-year survival rate was poorer than for other types of early gastric cancer, and amounted to 66.7% in cases that were curative, and 0% for non-curative cases.

Adenocarcinoma↗
PubMed1988

[Pharmacokinetic and clinical evaluations of ceftriaxone in perinatal infections in obstetrics and gynecology].

Ceftriaxone (CTRX), an injectable cephem antibiotic agent, was studied for its pharmacokinetic properties and clinical usefulness in perinatal infections in obstetrics and gynecology on a multicenter basis. The study results are summarized below. 1. Following the one-shot intravenous injection of CTRX 1 g to pregnant women before labor, the maternal serum level of CTRX reached a peak at 131.8 micrograms/ml soon after the injection then it began to decrease gradually. T 1/2 was 6.7 hours. The umbilical serum level reached a peak at 16.0 micrograms/ml at 4.9 hours post-dose and decreased gradually with a half-life of 8.1 hours. The umbilical serum level was higher than the maternal serum level at about 12 hours post-dose. The amniotic fluid level reached a peak of 9.6 micrograms/ml at 12.8 hours post-dose. T 1/2 was 15.2 hours. The amniotic fluid level at about 15 hours post-dose or later exceeded the maternal serum level and was almost equal to the umbilical serum level at 24 hours post-dose. 2. Clinical usefulness was evaluated in 79 evaluable cases out of 89 treated for various infections at puerperium or for prophylaxis of infections at cesarean section or premature rupture of membranes (PROM). The efficacy rate was 100% in 7 cases of prenatal infections such as urinary tract infection and 30 cases of postnatal infections such as puerperal intrauterine infections. In 42 cases treated for prophylaxis in cases of cesarean section or PROM, the efficacy rate was 92.9%. Bacteriologically, 29 strains of pathogens were isolated from 26 cases. The disappearance rate of the pathogens was 96.0% as 23 strains were eradicated, 1 strain was substituted and no change was observed in 1 strain with unknown results in 4 strain. Skin rash and itching appeared in 1 patient as an adverse effect (1.1%). There were 10 cases of abnormal clinical laboratory test results such as elevated transaminase level were observed in 7 patients (7.9%). From the results, CTRX was considered to be a useful drug for the perinatal infection in the obstetrics and gynecology fields.

Adult↗