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Biomedical subjects

T Oda

Publications and source records attributed to T Oda.

At least 847 records · Page 47Linked to original sources
PubMed1979

Effects of some polyamines, polyanions and antitumor drugs on replicative DNA synthesis and unscheduled DNA synthesis in vitro.

The effects of various compounds on replicative DNA synthesis in permeable mouse ascites sarcoma cells and on unscheduled DNA synthesis in permeable cells or in isolated rat liver nuclei were studied. Polyamines such as spermidine, putrescine and cadaverine inhibited replicative DNA synthesis. Unscheduled DNA synthesis was inhibited by spermidine and cadaverine, but slightly stimulated by putrescine at low concentrations. Aurintricarboxylic acid, a low molecular weight polyanion, inhibited both replicative DNA synthesis and unscheduled DNA synthesis. Replicative DNA synthesis was inhibited by heparin, a high molecular weight polyanion, whereas unscheduled DNA synthesis was stimulated at low heparin concentrations. Antitumor drugs such as daunomycin, neocarzinostatin and bleomycin inhibited replicative DNA synthesis. Unscheduled DNA synthesis was inhibited by daunomycin, slightly induced by neocarzinostatin and highly induced by bleomycin. The present system was thought to be useful for studying the separate effects of various drugs on either replicative DNA synthesis or unscheduled DNA synthesis in vitro.

Animals↗
PubMed1979

Photobinding of 8-methoxypsoralen and changes in nuclease digestability of replicating SV40 chromatin.

To analyze the structure of the replicating regions of simian virus 40 nucleoprotein complex (SV40 chromatin), photochemical binding of 8-methoxypsoralen (8-MOP) and changes in digestability with micrococcal nuclease were studied. 8-MOP bound preferentially to the linker DNA of nucleosomes and strongly inhibited nuclease digestion. Nuclease digestability of newly synthesized DNA in the replicating chromatin was markedly increased, but it was inhibited in the early time of nuclease reaction by photobinding of 8-MOP. The data suggest that the replicating regions of chromatin are more exposed than the bulk of mature chromatin.

Chromatin↗
PubMed1979

Characterization of RNA polymerases from Rous sarcoma virus-induced mouse ascites sarcoma cells.

RNA polymerase was extracted from the Schmidt-Ruppin strain of Rous sarcoma virus (SR-RSV)-induced C3H/He mouse ascites sarcoma cells (SR-C3H). RNA polymerase was separated into RNA polymerases I and II by DEAE-Sephadex chromatography. RNA polymerase I was separated into Ia and Ib fractions by phospho-cellulose chromatography. In SR-C3H cells RNA polymerase Ib was the main component of RNA polymerase I. At 0.05--0.1 M ammonium sulphate RNA polymerase I transcribed native DNA most actively, and RNA polymerase II transcribed denatured DNA most actively. Partial digestion of DNA by DNAase I enhanced RNA synthesis by RNA polymerases I and II. At ionic strength over 0.2 M ammonium sulphate, the initiation reaction of RNA polymerases I and II was inhibited. The initiation complexes of RNA polymerases I and II with native DNA were more stable against high salt concentration than with denatured DNA.

Animals↗
PubMed1979

Distribution of [3H]prednisolone entrapped in lipid layer of liposome after intramuscular administration in rats.

Positivery charged, sonicated liposome entrapping [3H]prednisolone was administered into the rats hip muscle to examine its absorption and distribution in comparison with that of the administration of free [3H]prednisolone. Plasma concentration of prednisolone in liposome-entrapped form showed high concentration for a long period of time, the values being 8 times after 30 min and 24 times after 24 hr compared to the free form. The concentration of liposome-entrapped form in liver, kidney and spleen was 4-10 times, and in lung and pancreas was 8-10 times higher than that of free form after 30 min and 24 hr. But, in adrenal, after 30 min and 1 hr, liposome-entrapped form were lower than that of free form, the former remained longer in the tissue, and the concentration maintained the high level after 24 hr, being about 28 times higher than that of free form. Even in the duodenum and large intestine, absorption of the liposome-entrapped form was very active and remained in the tissue for a long period of time. These facts suggested the possibility of using a small dose in intramuscular administration but allowing the steroid to remain in the tissues for a long period of time.

Animals↗
PubMed1979

Stabilizing effects of cholesterol on changes in membrane permeability and potential induced in red blood cells by lysolecithin.

Effects of cholesterol on permeability of K+ ion and on change in membrane potential induced by lysolecithin were studied. Cholesterol inhibited K+ release from rabbit red blood cells treated with lysolecithin (1.25 micrograms/ml), 3.3 X 10(-6) M of cholesterol being the optimum concentration for blocking K+ release. Changes in membrane potential, monitored by changes in intensity of fluorescence of cyanine dye, were induced by lysolecithin and inhibited by cholesterol. The inhibitory action on both K+ permeability and membrane potential varied with the cholesterol concentration. The observed effects are thought to be due to membrane-stabilizing activities such as decreasing membrane fluidity and hardening the membrane at the fluid-phase transition temperature. These properties of cholesterol may have significance in relation to transformed cells (tumor cells, lymphomed cells).

Animals↗
PubMed1979

[Daily and seasonal changes in the oviposition activities of Culex pipiens pipiens L. (author's transl)].

The oviposition activity of C. p. pipiens during summer and autumn has been investigated at two breeding sites in West and North Germany. The egg rafts were collected and counted daily or hourly. Soon after its begin oviposition reached a high peak and then decreased sharply and faded out towards sunrise. There was an obvious correlation between the hourly maximum number of egg rafts deposited and nightfall. The peak of oviposition regularly followed the sunset with one hour delay. It shifted with the changing daylight period according to the season and geographic latitude. The decrease and ending of the oviposition in September is considered not to be related to the decreasing temperatures, but to be due to the disappearance of the gonoactive summer generation and the predominance of the diapausing females of the over-wintering population.

Animals↗
PubMed1978

Inhibition of replicative DNA synthesis and induction of unscheduled DNA synthesis in permeable sarcoma cell by bleomycin.

Unscheduled DNA synthesis was induced by bleomycin in isolated rat liver nuclei and in permeable mouse ascites sarcoma cells. ATP significantly enhanced the bleomycin effect of inducing unscheduled DNA synthesis. Replicative DNA synthesis in permeable mouse ascites sarcoma cells was inhibited by bleomycin. The apparent inhibition or stimulation by bleomycin of in vitro DNA synthesis was thought to be determined by a balance between inhibited DNA replicase activity and induced unscheduled DNA synthesis.

Animals↗
PubMed1978

Role of fibrinolysis in development of hyaline membrane disease in newborn rabbits.

The role of fibrinolysis in the pathogenesis of hyaline membrane disease was studied in newborn rabbits at 28- or 29-day gestation. Hyaline membrane was recognized in the lungs of rabbits that were exposed to intrauterine hypoxia and received trans-4-aminomethylcyclohexane carboxylic acid (t-AMCHA), a plasmin inhibitor found to cause a marked decrease in the fibrinolytic activity of lung extracts. In the newborn rabbits subjected to intrauterine hypoxia alone, surface activity of lung extracts was reduced, but hyaline membrane was not seen. By immunofluorescent examination the hyaline membrane was found to be rich in fibrinogen and its derivatives. Electron microscopic examination revealed that they contained various amounts of cellular debris, bundles of fibrils and electron-dense, finely granular deposits and polymerized fibrin with 230 A periodicity. Disintegration of pulmonary epithelial cells was also seen. These findings indicate that diminished fibrinolytic activity of lung tissue contributes to intra-alveolar accumulation of fibrinogen, fibrin and their degradation products, thereby bringing about morphological and physiological disintegration of the terminal airways.

Animals↗
PubMed1978

Human fetal organ alkaline phosphatases.

The properties of human fetal alkaline phosphatase (ALP) have been compared with those of purified human adult hepatic and intestinal ALPs. The ALPs from different human fetal organs were divided into two groups. One terminated universal type was presented in fetal liver, spleen, adrenal, kidney, lung, heart, pancreas, thymus and bone, and was similar to adult hepatic-type ALP. The other terminated intestinal type was presented in fetal intestine and meconium and was similar to adult intestinal ALP. The activity of human fetal intestinal ALP increased markedly with the advance of intra-uterine life during fetal development, and that of human fetal thymus ALP increased slightly.

Adult↗
PubMed1978

Fractionation of aurintricarboxylic acid and effects of its components on nuclear swelling and nucleic acid synthesis.

Crude aurintricarboxylic acid synthesized by the conventional method was fractionated into 8 components (A1-A8) by silica gel thin layer chromatography. Some of the components were isolated and their effects were tested on nuclear swelling and on in vitro RNA synthesis and DNA synthesis using isolated polymerases. Only two components with low RF (A7 and A8) induced strong nuclear swelling. The other components were almost inactive. Formaurin-dicarboxylic acid, a contaminating polyanion of crude aurintricarboxylic acid, was synthesized separately. It was as effective as the two active components in nuclear swelling and inhibited RNA and DNA polymerases on naked DNA template. However, it stimulated RNA synthesis on chromatin template probably by dissociating histones from DNA. Unfractionated aurintricarboxylic acid showed the same effects at higher concentrations. A preliminary analysis indicated one of the inactive components (A4) is genuine aurintricarboxylic acid. The results suggest that the observed activity of crude aurintricarboxylic acid is due to some contaminating substances, one of which is formaurindicarboxylic acid.

Animals↗