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Biomedical subjects

O Yamada

Publications and source records attributed to O Yamada.

At least 235 records · Page 13Linked to original sources
PubMed1983

Pyridine nucleotide synthesis in human blood--effect of leucine, alpha-ketoisocaproic acid and ketone bodies.

The effects of L-leucine and its metabolites on pyridine nucleotide synthesis were investigated in human blood. After 30 min-incubation 40% of the added (carboxyl-14C)-nicotinic acid was incorporated into pyridine nucleotides, most of which was nicotinic acid mononucleotide. Leucine and alpha-ketoisocaproic acid reduced pyridine nucleotide synthesis by 40% and 15%, respectively at 1 mM level. Ketone bodies were without effect. The results were different from those observed in rat hepatocytes [O. Yamada et al.: Internat. J. Vitam. Nutr. Res. 53, 184 (1983)], in which ketone bodies and the compounds metabolized to ketone bodies were inhibitory to the NAD biosynthesis.

Adenine Nucleotides↗
PubMed1983

[Evaluation of pulmonary regurgitation with a catheter-tip electromagnetic velocity probe].

Pulmonary regurgitation appeared after the surgical repair of pulmonary stenosis was investigated with an electromagnetic catheter-tip velocity probe in seven patients. Postoperative catheterization was performed by placing the probe in the pulmonary trunk transvenously and a velocity curve was recorded on a photographic recorder at a paper speed of 150 or 200 mm/sec with electrocardiograms and pulmonary arterial pressure pulse. The velocity curves were recorded under the baseline throughout diastole in patients with pulmonary regurgitation, while the curves in the normal controls were just on the baseline. The amount of regurgitation was evaluated with the ratio of the negative to positive area of velocity curves. The negative area (NA) was defined as an area circumscribed by the diastolic negative velocity curve and the baseline, and the positive area (PA) as an area circumscribed by the systolic positive curve and the baseline. The amount of the regurgitation was also evaluated from either the pulmonary cineangiogram or the volume measurement using the right arteriogram. The results were as follows: The severity of pulmonary regurgitation estimated by the pulmonary arteriogram (grade I to III) tended to be correlated with the ratio of the NA/PA. Right ventricular end-diastolic volume index (RVEDVI) and the NA/PA showed a fair correlation with a coefficient of 0.80. Right ventricular volume overload resulting from pulmonary regurgitation was reflected on the NA/PA. The subtraction of right and left ventricular systolic ejection indices (RVSI-LVSI) or its ratio (RVSI-LVSI)/RVSI, which were considered as the indices of the severity of pulmonary regurgitation from the volume measurement, had fairly good a correlation with the NA/PA.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1983

Effect of leucine and alpha-ketoisocaproic acid on NAD biosynthesis from tryptophan or nicotinic acid in the isolated rat liver cells.

The effects of leucine and alpha-ketoisocaproic acid on the NAD biosynthesis from (carboxyl-14C) nicotinic acid or (benzene ring-U-14C) tryptophan were investigated in the isolated rat liver cells. The quantities of NAD formed from tryptophan and nicotinic acid increased linearly during 60 min-incubation. Leucine, which was essentially not metabolized by the isolated liver cells, had no inhibitory effect on the NAD synthesis. On the other hand, alpha-ketoisocaproic acid, alpha-keto acid analogue of leucine, which was rapidly metabolized to ketone bodies, diminished a quantity and a specific radioactivity of NAD synthesized from both tryptophan and nicotinic acid to a similar extent. Palmitic acid, which was oxidized to ketone bodies by the isolated rat liver cells, also diminished an amount and a specific radioactivity of NAD synthesized from nicotinic acid. Ketone bodies exogenously added to the incubation medium exerted a similar inhibitory effect on NAD synthesis. Results demonstrate that substances which can be oxidized to ketone bodies are inhibitory to NAD biosynthesis from tryptophan and nicotinic acid in the isolated rat liver cells.

Animals↗
PubMed1983

Effect of dietary excess leucine on the levels of branched chain alpha-keto acids and ketone bodies in blood and the liver of rats.

Male rats were fed either a 10% casein diet or a 10% casein diet supplemented with 5% leucine, and the levels of alpha-ketoisocaproic acid and ketone bodies were analyzed in blood and the liver. alpha-Ketoisocaproic acid in plasma increased significantly on the 1st day of feeding the leucine-supplemented diet and was maintained on the high level during the experimental period of 7 days. Other branched chain alpha-keto acids tended to decrease in plasma. beta-Hydroxybutyric acid in blood doubled its amount on the 1st day on the high leucine diet and was maintained high during the experimental period. The sum of acetoacetic acid and beta-hydroxybutyric acid in blood was kept on a level twice as high as that of the control group. Ketone bodies in the liver were similarly increased and the sum of acetoacetic acid and beta-hydroxybutyric acid in the liver corresponded to the level found inhibitory to NAD biosynthesis in in vitro system [YAMADA, O., et al.: Int. J. Vit. Nutr. Res. 53, 184 (1983)].

Animals↗
PubMed1982

Enhancement of granulocyte-endothelial cell adherence and granulocyte-induced cytotoxicity by platelet release products.

Complement-stimulated granulocytes adhere to and induce significant 51Cr release from endothelial cells in vitro. Platelets were stimulated to undergo release, and these release products significantly enhanced granulocyte-endothelial cell adherence and granulocyte-induced 51Cr release from endothelial cells. Platelet serotonin appeared to mediate these phenomena because serotonin antagonists blocked both the enhanced endothelial adherence and 51Cr release. In addition, added serotonin mimicked the effect seen with the stimulated platelets upon granulocyte--endothelial cell adherence and cytotoxicity completely. This enhancement appeared to be due to serotonin effects upon both the granulocyte and endothelial cells. These data suggest that a released platelet constituent might modulate in vivo granulocyte-endothelial cell interactions in clinical disorders.

Blood Platelets↗
PubMed1982

Contributing generator of frequency-following response in man.

A contributing generator of the frequency-following response (FFR) was identified in a patient with severe neurological impairment, by comparing latencies and phase shifts of the FFR to the latency of the auditory brainstem evoked responses (ABR), and by comparing the duration of the FFR to that of the acoustic stimulus. In this patient, the ABR comprised only waves I and II; activity in the inferior colliculus was not identified. Both onset and offset latencies and phase shifts of the FFR were substantially shorter than the latency of the first wave of the ABR. The duration of the FFR corresponded precisely to that of the acoustic stimulus. These results are interpreted as supporting the view that the cochlear microphonic potential (CM) contributes to the scalp-recorded FFR.

Brain↗
PubMed1982

Effect of branched chain alpha-keto acids on kynurenine 3-hydroxylase from rat liver.

In the preceding paper, we found that branched chain alpha-keto acids, alpha-ketoglutarate and pyruvate were inhibitory to kynurenine 3-hydroxylase [EC 1.14.1.2] from Saccharomyces (Shin, M. et al. (1982): J. Nutr. Sci. vitaminol., 28, 191-201). As kynurenine 3-hydroxylase is reported to be a rate-limiting enzyme in the tryptophan-NAD pathway in rats, branched chain amino acids, branched chain alpha-keto acids and several other keto acids were tested for their effects on kynurenine 3-hydroxylase activity in the mitochondrial outer membrane fraction prepared from rat liver. In contrast with the yeast enzyme, the rat liver enzyme was resistant to alpha-keto acid-inhibition and more than 70% of the enzyme activity was maintained even in the presence of 20 mM of each alpha-keto acid. The present result implies that the mechanism of the hepatic NAD-lowering effect of leucine in rats might be completely different from that operative in Saccharomyces.

Amino Acids, Branched-Chain↗
PubMed1982

NAD glycohydrolase activity in the liver of rats fed on excess leucine diet and low or high protein diet.

In rats fed for 2 weeks on a 10% casein diet supplemented with 5% leucine, the hepatic NAD content was lowered when comparing with the control rats pair-fed on the 10% casein diet. The hepatic NAD glycohydrolase [EC 3.2.2.5] activity increased by 25% in the leucine-supplemented diet-fed rats and by 40% in the nicotinic acid-free diet-fed rats. The hepatic NAD glycohydrolase activity in the rats fed on the nonprotein diet freely for 1 week was elevated by 60% compared to the rats fed on the 18% casein diet. The hepatic NAD content in the former animals was significantly lower than that in the latter. The 70% casein diet caused changes in neither hepatic NAD content nor NAD glycohydrolase activity. These results indicated an inverse relationship between hepatic NAD content and NAD glycohydrolase activity.

Animals↗
PubMed1982

Transplantation of the reversed dermis from skin leading to repair of the buccal mucosal epithelium.

Skin grafting or mucosal grafting has been widely applied as the established method to compensate mucosal defects. However, in the grafted skin the epidermis never transformed into the mucosal epithelium; the original nature of the transplant was maintained as skin. The available donor of mucosa is also strictly limited. Therefore, an improvement in method has been much needed in the field of oral surgery. We tried to transplant the dermis freed completely from the epidermis instead of the full-thickness skin, and succeeded in compensation of the mucosal defect. The defects of the buccal mucosa in 30 dogs were repaired, one side with reversed dermis graft (RDG) in which the dermis was turned inside out and sutured onto the bed. On the other side, the ordinary free full-thickness skin graft (FTSG) was carried out as a control. Comparative clinical and histological observations were conducted to analyze the healing processes. In RDG the graft was covered by the surrounding mucosal epithelium to form the mucosal tissue, while the implanted tissue inhibited the wound constricture. Histological examination revealed that the epithelial elements underwent degeneration, presumably through being embedded by the grafting of the dermis inside out. The epithelium covering the dermis graft seems to be nothing but normal oral mucosal epithelium.

Animals↗