Biomedical subjects
Publications and source records attributed to Y Kiso.
Among phyllanthin, hypophyllanthin, triacontanal and tricontanol isolated from a hexane extract of Phyllanthus niruri, phyllanthin and hypophyllanthin protected against carbon tetrachloride- and galactosamine-induced cytotoxicity in primary cultured rat hepatocytes, while triacontanal was protective only against galactosamine-induced toxicity.
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Effects of synthetic alpha human atrial natriuretic polypeptide (alpha-hANP) on diuresis, natriuresis and mean arterial blood pressure (MAP) were compared between 4-5 month-old male spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY) under ether anesthesia. In both groups, the peptide injected (0.5 micrograms/100g body weight, i.v.) caused potent (about ten fold), rapid and short-acting (for 15 min) increases in sodium (Na+) and chloride excretions and also an increase in urine flow and potassium excretion with lesser magnitude. Although ratios of the maximum response to basal value were much the same, net increases in urine flow and Na+ output were significantly greater in SHR than in WKY. As to the effect on MAP, a rapid (within 2 min) fall observed in the two groups. These results suggest that the atrial natriuretic peptide may be involved in the altered regulatory mechanism of fluid and electrolyte balance in SHR models with genetic hypertension.
Genetically mast cell-deficient (WB X C57BL/6)F1-W/Wv mice were used to investigate the role of mast cells for the acquisition of resistance against larval Haemaphysalis longicornis ticks. Resistance against ticks was evaluated by reduction in both number and weight of engorged ticks. Although (WB X C57BL/6)F1-+/+ mice with a normal number of mast cells acquired resistance after repeated infestation of ticks, the congenic W/Wv mice did not acquire it. Bone marrow transplantation from the +/+ mice were grafted onto the back of the W/Wv mice, resistance against the ticks was detectable in the grafted skin. In contrast, resistance was not detectable in the skin of the W/Wv mice which had been grafted onto the back of the syngenic W/Wv mice. Thus, we consider that the failure of the W/Wv mice to manifest resistance is attributable to the mast cell depletion.
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The tripeptides SD-34 and SD-25 induced atropine-, guanethidine-, antihistaminics-resistant but naloxone-sensitive contractions of isolated rat distal colon. They appeared to act on an opioid receptor, probably of the mu subtype, distinct from those for methionine enkephalin and morphine, because the pA2 values of naloxone for the peptides were similar to those for mu-agonists but different from those for methionine enkephalin and morphine, and because the peptides caused contractions of colon that had been desensitized to morphine. Mr 2266, a supposed kappa-antagonist, inhibited the actions of the peptides, ethylketocyclazocine and dynorphin at concentrations much lower than those inhibiting the actions of methionine enkephalin and morphine. Thus these peptides seem to act on the mu- and/or kappa-receptors. The actions of the tripeptides were inhibited by methysergide and methylergometrine, but not by the 5-HT2 antagonist ketanserin, and were not affected by 5-HT or substance P autodesensitization . Thus their actions do not seem to involve 5-HT, histamine, ACh or substance P. It seems likely that the tripeptides, through opioid receptors, directly activate the muscle, or remove some inhibitory modulation of myogenic activity, thus causing contractions.
Experimentally determined optimum separation conditions for a metabolite of anaesthetic halothane in urine, trifluoroacetic acid, were assessed by means of computer simulation of the isotachophoretic steady-state. The simulation confirmed that urinary acids and trifluoroacetic acid can be separated in the limited pH range of 3.5-3.7 buffered by beta-alanine, as far as the pH dependence of effective mobility is utilized. The separated fraction of the trifluoroacetic acid zone was identified by mass spectrometry. The simulated coefficient of the calibration curve agreed well with the observed value.
Antihepatotoxic actions of the papyriogenins and papyriosides from Tetrapanax papyriferum leaves were examined utilizing carbon tetrachloride (CCl4)- and galactosamine (GalN)-induced cytotoxicity in primary cultured rat hepatocytes. Remarkable antihepatotoxic effects were observed with papyriogenin B, papyriogenin A, propapyriogenin A2, papyriogenin C, 11-dehydropropapyriogenin A2, 16-epi-saikogenin C and propapyriogenin A1 in the CCl4-induced cytotoxicity assay, and papyriogenin A, propapyriogenin A1 and propapyriogenin A2 were active in preventing GalN-induced cytotoxicity although these triterpenoids were rather cytotoxic at a higher dose in the latter assay. Structure-activity relationship is discussed.
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