Biomedical subjects
Publications and source records attributed to N Yamazaki.
After acute myocardial infarction, serial serum dopamine-beta-hydroxylase (DBH) activity was elevated in both high and low DBH subgroups. The observed increase in DBH activity on the first, second, and third days after acute myocardial infarction suggests an augmentation in sympathetic nervous system activity after acute myocardial infarction.
Isatin, an endogenous monoamine oxidase (MAO) inhibitor, has been found in mammalian tissues. We previously reported that exogenously administered isatin significantly increased acetylcholine (ACh) and dopamine (DA) levels in the rat striatum. In order to elucidate the relationship between isatin and Parkinson's disease, we measured urinary isatin excretions in patients with Parkinson's disease using a newly developed HPLC-UV method. The recovery of this assay was approximately 102.3% at a range from 2 to 50 nmol/ml. The Coefficient of Variance (CV) for the determination at this range was approximately 2.5% for intra-assay and 6.2% for inter-assay, respectively. There was no significant difference in urinary isatin excretion between data from men and women in healthy control. The value in young age group (19-35 years old) was not significantly different compared with that of the older age group (54-84 years old). Urinary isatin levels in patients with Parkinson's disease tended to increase in accordance to the Hoehn and Yahr criteria. This is the first study in which a significant increase in urinary isatin excretion was observed at Stage III, IV and V in patients with Parkinson's disease. Urinary isatin concentrations in drug-treated patients with Parkinson's disease (at Stage I and II) tended to decrease compared with those of patients without medication. These results demonstrated that urinary isatin excretion may serve as an endogenous diagnostic marker for the clinical severity of Parkinson's disease.
The formation of free radicals, which was represented by the concentration of free radicals in state 4 respiration, and the respiratory control ratio were studied in the myocardial mitochondria isolated from dog hearts that were failing due to aortic constriction. Both formation and respiratory control ratio were lowered, compared to each control value, in acute and chronic heart failure. A positive correlation was recognized between free radicals in state 4 respiration and respiratory control ratio. From these results it was concluded that there was uncoupling of oxidative phosphorylation in the mitochondria isolated from failing dog hearts. Measurement of free radicals in state 4 respiration, as well as respiratory control ratio, is a useful method for evaluation of the function of oxidative phosphorylation.
The mechanism of action of the acute abnormal rise of plasma free fatty acids (FFA) in the provocation of arrhythmia in ischemic heart was studied by means of electron spin resonance (ESR) spectrometer. A sudden and abnormal rise of plasma FFA caused a significant fall of the respiratory control index (RCI) of the amount of free radical myocardial mitochondria in state 4 respiration. Based on these findings, a sudden and abnormal rise of plasma FFA seems to further facilitate the uncoupling of oxidative phosphorylation in the myocardial mitochondria of the ischemic portion of the heart. These observations indicate that it may play an important role in the provocation of arrhythmia by high plasma FFA on the ischemic heart. Nicomol (2,2,6,6,-tetrakis (nicotinoyloxymethyl) cyclohexanol), an inhibitor for the rapid rise of plasma FFA, was effective in the treatment and prevention of arrhythmia in ischemic heart disease and diabetes mellitus.
Human colon carcinoma cells were treated with non-toxic levels of sodium butyrate, retinoic acid or phorbol ester, eliciting characteristic growth inhibition and morphological changes. Since protein-carbohydrate interactions are supposedly involved in regulatory processes and can serve within targeted drug delivery, the capacity to bind components of the carbohydrate chains of cellular glycoconjugates was monitored for such cells in relation to the type of the medium additive. The pattern of binding of a panel of neoglycoproteins was significantly altered for fixed cells, depending on the type of putative maturation factor. Quantitation of cell surface sugar receptors at a non-saturating concentration of neoglycoenzyme, employed as carbohydrate ligand-exposing probe, led to a similar conclusion. Up to six-fold increases were determined for individual probes. Binding studies with varying concentrations of neoglycoenzymes in the case of four ligands revealed that the receptor density, but not the affinity was significantly affected. Biochemical analyses corroborated this result by demonstrating mainly quantitative differences after affinity chromatography of detergent extracts from the four types of cell pellet. By showing the inhibitory potency of neoglycoprotein-conjugated liposomes in the cell binding assay with neoglycoenzymes, a perspective is indicated, of how the different effects of the differentiation-inducing agents might be beneficially exploited in targeted drug delivery.
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