Search PubMed⌕ Search

Biomedical subjects

H Ide

Publications and source records attributed to H Ide.

At least 415 records · Page 23Linked to original sources
PubMed1983

Radiation-induced conversion of 5,6-dihydropyrimidines to the corresponding pyrimidines in N2O-saturated aqueous solutions.

The effect of transition metal salts on the radiation-induced conversion of 5,6-dihydropyrimidines to the corresponding parent pyrimidines was studied in N2O-saturated aqueous solution at pH 7.0. The yield of the pyrimidines increased in sigmoidal forms with the increased one-electron reduction potential of the transition metal salts. The radiolysis of 5,6-dihydroorotic acid suggested that the 6-yl radical of the acid undergoes oxidation by transition metal salts to give orotic acid, whereas the corresponding 5-yl radical readily liberates CO2 to give uracil radical anion.

Gamma Rays↗
PubMed1982

Cholinephosphotransferase in rat lung. In vitro formation of dipalmitoylphosphatidylcholine and general lack of selectivity using endogenously generated diacylglycerol.

Diacylglycerol was generated in vitro in rat lung microsomes by forming phosphatidic acid via sn-glycerol-3-phosphate acyltransferase followed by the hydrolysis of the phosphatidic acid by phosphatidate phosphohydrolase. Diacylglycerol concentrations of 35 to 50 nmol/mg of microsomal protein were obtained. Cholinephosphotransferase activity was determined in microsomes by measuring the conversion of endogenously generated [14C]diacylglycerol to phosphatidylcholine. Reaction rates of 14 to 16 nmol/min/mg of protein were obtained with a 30-s reaction. Diacylglycerol which was primarily dipalmitoylglycerol was produced when palmitic acid was used in the sn-glycerol-3-phosphate acyltransferase reactions. Dipalmitoylphosphatidylcholine was formed via cholinephosphotransferase from the dipalmitoylglycerol with an apparent maximal velocity of 20 nmol/min/mg of protein. When oleic acid was used instead of palmitic acid, the apparent maximal velocity for cholinephosphotransferase was 26 nmol/min/mg of protein. The apparent Km values for the two different diacylglycerol substrates were the same (28.5 nmol/mg of protein). Diacylglycerols, with different molecular species composition, were generated using a variety of fatty acids and fatty acid mixtures. The phosphatidylcholine formed from these diacylglycerols had the same molecular species profiles as the diacylglycerol used as the substrate. The relative reaction rates with the different diacylglycerols were essentially the same except when 20:4 and 22:6 fatty acids were used individually, in which case the rates were lower. We conclude that cholinephosphotransferase readily forms dipalmitoylphosphatidylcholine from endogenously generated dipalmitoylglycerol and that the cholinephosphotransferase reaction is generally nonselective for the diacylglycerol substrate.

Animals↗
PubMed1982

Properties of diacylglycerol kinase in adult and fetal rat lung.

Diacylglycerol kinase activity is found in both adult and fetal lung. Approximately 27 and 52% of the total activity is found in microsomes and cytosol, respectively. The activity is maximal at pH 7.4. The apparent Km for ATP is 0.11 mM and 0.21 mM for cytosol and microsomes, respectively. The apparent Km for dioleoylglycerol is 0.05 mM for cytosol and 0.14 for microsomes. Maximal activity in cytosol and microsomes is obtained with 2.0 mM dexoycholate. Other detergents cannot substitute for deoxycholate. Phosphatidylglycerol stimulates activity in the absence and in the presence of deoxycholate. Phosphatidylserine also stimulates activity, whereas phosphatidylethanolamine was inactive and phosphatidylcholine inhibited the reaction. Linoleic acid produced inhibition. The general properties of the enzyme were similar for fetal and adult lung. Diacylglycerol kinase from microsomes and cytosol fraction from both fetal and adult lung was most active with dioleoylglycerol and diacylglycerol from egg phosphatidylcholine. Significantly lower activity was obtained with dipalmitoylglycerol. Phosphatidylglycerol did not alter the relative substrate preferences. The activity in microsomes increased with development from 19 days gestation to a maximal activity at 21 days gestation. Maximal activity was about 2-fold higher than the adult. The activity dropped rapidly reaching adult values prior to birth (22 days gestation). The activity in cytosol fractions increased gradually from 19 days gestation, reaching adult values by 22 days gestation.

Animals↗
PubMed1982

Radiation-induced reactions of thymine, thymidine and thymidine-5'-monophosphate in aqueous solutions.

Radiochemical reactivities of thymine (T), thymidine (Td), thymidine-3' and 5'-monophosphates (3'-, 5'-TMP) and thymidylyl (3' leads to 5') thymidine (TpT) varied in the following order: [A] T (G-value for decomposition, 1.81) less than Td (2.14) less than 3'-TMP = TpT (2.51) less than 5'-TMP (2.76) in deaerated aqueous solution; [B] TpT (2.82) less than T (3.17) congruent to Td (3.18) less than 3'-TMP (3.49) less than 5'-TMP (3.65) in N2O-saturated aqueous solution; [C] T (2.70) congruent to TpT (2.73) less than Td (2.81) less than 3'-TMP = 5'-TMP (3.47) in deaerated aqueous solution containing sodium formate.

Aerobiosis↗
PubMed1981

Effect of chlorpromazine on intracellular transport of phospholipids.

The transfer of phosphatidylinositol from rat liver microsomes to liposomes stimulated by cytoplasmic protein was found to be inhibited by the addition of chlorpromazine, while the phosphatidylcholine transfer was not affected. The administration of chlorpromazine has been shown to enhance the synthetic rate of phosphatidylinositol and is assumed from the present experiment to decrease the intracellular transfer rate, leading to the accumulation of phosphatidylinositol in the endoplasmic reticulum. On the other hand, chlorpromazine caused the depression of the secretion of phosphatidylcholine to the blood plasma. Thus, the phospholipid composition of rat liver endoplasmic reticulum seems to remain unchanged by the balance of the intracellular alterations of phospholipid metabolism.

Animals↗