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Biomedical subjects

Y Okano

Publications and source records attributed to Y Okano.

At least 325 records · Page 18Linked to original sources
PubMed1980

Seasonal and activity-dependent variations of piperidine levels in the amphibian brain.

Piperidine is one of biogenic amines possessing nicotine-like synaptotropic actions on the nervous systems. Since piperidine produces multiplex physiological actions, a role for the amine as a modulator in neuroendocrine as well as neuronal functions has been supposed. In the present study, piperidine levels in the amphobian brains during activity and hibernation were examined by use of a mass fragmentographic technique and it was found that the brain piperidine concentrations significantly increased in the cold season especially during hibernation. The significance of the findings is discussed with respect to the hypnogenic effect of piperidine.

Animals↗
PubMed1980

Electrophoretic study of pipecolic acid, a biogenic imino acid, in the mammalian brain.

Pipecolic acid (PA), one of the imino acids, is a normal constituent in the mammalian brain. It is said that PA is a major intermediate of lysine metabolism in the rat brain. Biochemical studies have suggested that PA may be involved in the regulation of synaptic mechanism in the CNS. Moreover, the pathophysiological significance of PA has been also suggested by some investigators. However, there has so far been no good evidence based on the comprehensive electrophysiological experiments. Using unit recording and microelectrophoretic technique, the action of PA on single neuron activities in the rat brain was examined. PA depressed the firing of 88 out of 115 cortical neurons tested. Only 2 were excited and 25 remained unaffected. All the identified hippocampal pyramidal neurons examined were uniformly inhibited. It has been reported that PA inhibits the uptake of GABA into the brain slices and enhances the release of GABA from the slices. Thus, it is likely that the inhibitory response due to PA may have some connections with GABAergic transmission. On the other hand, it remains to be clarified whether the specific PA sensitive receptors exist in the brain. Our findings provide a clue to the elucidation of the presumed synaptic involvement of PA in the CNS.

Animals↗
PubMed1980

Erythrocyte membrane abnormalities in experimental biliary obstruction: comparative studies on erythrocyte membranes from rats with intra- and extrahepatic cholestasis.

The red blood cells from rats with intra- and extrahepatic cholestasis obtained by feeding of alpha-naphthylisothiocyanate (ANIT) and ligation of bile duct, respectively, were analysed from biochemical as well as ultrastructural point of view. A significant increase of cholesterol content was observed in the red cell membrane from bile duct-ligated rat. An increment of absolute lecithin content without accompanied increase in phospholipid content was observed in both groups. The fatty acyl chain composition of lecithin remained unchanged except a small increase in stearic acid (13.0% leads to 18.1%) in the bile duct-ligated rat. Despite a small change in the lipid composition, scanning electron microscopic observation revealed a profound alteration in red cell ultrastructure; most of cells were in spur type in ANIT-fed group while variations in red cell shape were observed in bile duct-ligated group.

Animals↗
PubMed1979

Abnormalities of erythrocyte membranes in biliary atresia: ultrastructure and lipid composition.

Biochemical and ultrastructural studies of red blood cell membranes from seven patients with congenital biliary atresia have been performed. Scanning electron microscopic observations revealed that more than half of these cells were of abnormal shapes, such as target, spur and cup-formed cells. By freeze-fracture electron microscopy, membrane particle-free smooth areas were noted in the fracture faces. In addition, the number of membrane-associated particles was 20% less than those in control subjects. The lipid analysis of red blood cells showed a significant increase in phospholipid and a marked increase in cholesterol content. The increase of phospholipid content was primarily caused by the increase of lecithin. The acyl chain analysis of erythrocyte lecithin demonstrated an increase in palmitic, palmitoleic and oleic acid, and a decrease in stearic and linoleic acid. These observations are similar to those of acquired biliary obstruction. The fluidity of erythrocyte membrane lipid, studied by a fluorescence technique using fluorescent probe 1,6-diphenyl-1,3,5-hexatriene (DPH), was found to be less in an individual with congenital biliary atresia than in the control subject.

Bile Ducts↗
PubMed1978

Mechanism for lipid abnormalities of erythrocyte membranes in biliary obstruction: lecithin content and its fatty acyl composition.

The lipid compositions of erythrocyte membranes, plasma and bile of 16 patients with biliary obstruction were analysed to obtain information regarding the origin of excess lecithin which is usually found in the erythrocyte membranes in obstructive jaundice. Phospholipids and free cholesterol were found to be increased proportionally to the degree of biliary obstruction with an elevation in the free cholesterol/phospholipid ratio in the red cell membranes. The increase in phospholipid content is primarily due to lecithin. There was a highly significant alteration in the fatty acid composition of lecithin of erythrocyte membranes, plasma and bile from patients with severe jaundice. Red cell membrane lecithin amounted to more than 40% of the total phospholipid in these patients. Interestingly, the fatty acid composition of lecithin showed a similar pattern in erythrocyte membranes, plasma and bile. In addition, the fatty acyl chain composition of lecithin in lipoprotein-X was very similar to that of the red cell membrane. Freeze-fracture electron microscopy showed an alteration in membrane morphology and a reduced number of membrane-associated particles in the fractured faces. From these findings, we suggest that the lecithin of lipoprotein-X is derived from abnormal bile lecithin, which is incorporated into erythrocyte membranes by fusion with lipoprotein-X. On the other hand, the fatty acid composition of bile lecithin from patients with mild jaundice, whose erythrocyte membrane lecithin amounted to less than 31% of total phospholipid, was not different from that of normal individuals. However, in sharp contrast to the bile content, the fatty acid composition of erythrocyte membranes and plasma in these same patients showed a similar but small change compared to that of patients with severe biliary obstruction. The red cells of patients with mild jaundice were almost normal, biconcave disc-shaped, as observed by scanning electron microscopy and no abnormalities in the distribution or number of membrane particles were detected by freeze-fracturing. We propose that the abnormal lecithin content of erythrocyte membranes in patients with mild jaundice can be explained by the gradual exchange of lecithin between red blood cells and plasma lipoprotein.

Adult↗
PubMed1978

Metabolites of piperidine in rat urine.

Piperidine is one of pharmacologically active biogenic amines. While two pathways for piperidine production have been reported, little is known about metabolism of the compound. In the present study, piperidine and its hydroxylated, conjugated and unknown metabolites were detected in rat urine by radiochromatographic analysis. Using GC-MS technique, it was confirmed that 3-hydroxypiperidine and 4-hydroxypiperidine are major metabolites of piperidine of either exogenous or endogenous origin. The findings substantiate the existence of a mechanism which inactivates piperidine in the living body, since both metabolites lack the potent pharmacological activities as those induced by piperidine.

Acetylation↗
PubMed1978

[Action of 4-amino-alpha-](tertbutylamino) methyl]-3, 5-dichlorobenzylalchol hydrochloride (N-AB 365, clenbuterol) on the respiratory system (author's transl)].

The bronchodilating effect and other related pharmacological properties of N-AB 365 were studied in comparison with those of isoproterenol, salbutamol and clorprenaline. N-AB 365 was found to produce a bronchodilating effect 1/20 approximately 1/100, 1/10 approximately 1/40 and was 2 to 5 times as strong as effects of isoproterenol, salbutamol and clorprenaline, respectively. The bronchodilating effect of N-AB 365 was sustained more than 10 times as long as those of isoproterenol and salbutamol, and in particular with oral administration, was much more potent. The bronchodilating effect of N-AB 365 seems to be due mainly to excitation of the adrenergic beta2-receptor and partially to papaverine-like action. N-AB 365 showed an inhibitory effect on experimentally induced bronchial asthma by spraying of bronchoconstrictors and the effect by oral administration was much stronger than those of isoproterenol and salbutamol. N-AB 365 affected neither the volume output of respiratory tract fluid nor the tracheal ciliary movement with the doses around ED50 in bronchodilating action, however, it increased ciliary activity and decreased the volume output of respiratory tract fluid with large doses. Antitussive effect was also demonstrated only with the large doses. N-AB 365 induced a moderate decrease in blood pressure through vasodilatation but did not influence respiration. The effect of N-AB 365 on heart rate varied. There were cases of no change, slight increase or slight decrease in heart rate.

Acetylcholine↗
PubMed1977

Studies on Tetrahymena membranes. Palmitoyl-coenzyme a desaturase, a possible key enzyme for temperature adaptation in Tetrahymena microsomes.

(1) Microsomes from a thermotolerant Tetrahymena NT-1 catalyze the conversion of palmitoyl-CoA to palmitoleate. (2) Palmitoyl-CoA desaturase enzyme requires molecular oxygen and NADH or NADPH as cofactor and its activity is inhibited by cyanide. A pH optimum range 7.0--7.3 is observed. (3) There is a clear break at 30 degrees C and a slight bend around 15 degrees C in the Arrhenius plots of palmitoyl-CoA desaturase activity. (4) After quenching from 39.5 degrees C, at 26 degrees C microsomal membranes show small particle-free areas, when examined by freeze-fracture electron microscopy, indicating the onset of phase separation. Larger smooth areas devoid of membrane-intercalated particles are observed in microsomes at 23 and 15 degrees C. The results support evidence that the thermally induced transition of desaturase enzyme activity in related to the altered membrane properties due to temperature change.

Adaptation, Physiological↗
PubMed1976

Herniation of the singular nerve into the round window niche.

We report two cases of herniation of the singular nerve into the round window niche and one case of bony dehiscence without herniation between the round window niche and the posterior canal ampulla. It is believed that the middle ear and the inner ear are completely separate. However, in the temporal bone of a 10- to 15-week-old human fetus, a communication between the round window niche and the posterior canal ampulla is observed. Later, the mesenchymal tissue in the communication is replaced by cartilage from near the posterior canal ampulla. If the communication does not fill with cartilage, ossification is not able to begin behind the posterior canal crista. When there is bony dehiscence behind the crista, the singular nerve fibers are easily pressed out by ossified endosteal bone and herniated into the round window niche.

Ear↗