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Biomedical subjects

Y Kamiyama

Publications and source records attributed to Y Kamiyama.

At least 235 records · Page 13Linked to original sources
PubMed1976

A direct method for the estimation of ornithine carbamoyltransferase activity in serum.

Ornithine carbamoyltransferase (EC 2.1.3.3) activity was estimated by determining the amount of citrulline produced. The citrulline was colorimetrically measured by using a diacetylmonoxime-thiosemicarbazide reaction without deproteinization. The color complex which had the maximum absorbance at 515 nm was stable at room temperature in daylight for at least several hours. The proposed method was superior to other methods already reported in sensitivity, stability and simplicity.

Citrulline↗
PubMed1976

Changes in mitochondrial phosphorylative activity and adenylate energy charge of regenerating rabbit liver.

The changes in the cellular concentrations of ATP, ADP, and AMP and in oxidative phosphorylation of mitochondria were investigated in the remaining liver of partially hepatectomized rabbits. The energy charge (defined as half of the average number of anhydride-bonded phosphate groups per adenosine moiety) of the liver remnant decreased from 0.866 to 0.767 (p less than 0.01) within 24 hr after hepatectomy, and then increased to a substantially higher level than normal within 7 days. On the other hand, the mitochondrial phosphyorylative activity increased rapidly to 170 per cent of the control within 12 hr and then retruned to normal within 7 days. The mitochondrial phosphorylative activity was inversely correlated with energy charge of the liver remnant (r = -0.75, p less less than 0.01). The maximal enhancement of mitochondrial phosphorylative activity was found in mitochondria obtained from the liver remnant with the lowest level of energy charge, suggesting a response of mitochondria in vivo involving enhanced biosynthetic ATP-utilizing reactions at an early stage of the regenerating process. The enhancement of phosphorylative activity was accompanied by a rise in the respiratory control ratio, P/O ratio and state 3 respiration. The adenylate kinase [EC 2.7.4.3] activity in the liver remnant increased to more than 160% of the control within 2 days after partial hepatectomy, while the pyruvate kinase [EC 2.7.1.40] activity decreased remarkably. However, the changes in the two enzyme activities did not correlate with those of mitochondrial phosphorylative activity or the energy charge of the liver remnant.

Adenosine Diphosphate↗
PubMed1976

Changes in adenylate energy charge of the liver after an oral glucose load.

Changes in the adenine nucleotide metabolism after an oral glucose load were studied in the liver of normal and alloxan-diabetic rats. Changes in the energy charge were positively correlated with those in the blood glucose and plasma immunoreactive insulin levels. One hour after an oral glucose load when the plasma immunoreactive insulin levels increased maximally, the energy charge increased maximally from 0.846 to 0.867 (P less than 0.001). The increase in the energy charge was accompanied by a concomitant decrease in the ADP levels (P less than 0.05). The respiratory control ration, state 3 respiration per unit of cytochrome a (+a3), and DNP-induced ATPase activity per unit of cytochrome a (+a3) increased significantly. The adenylate kinase and pyruvate kinase activities in the liver remained unchanged. On the other hand, the energy charge in the liver of alloxan-diabetic rats did not increase significantly after an oral glucose load. It was suggested that an increase in the energy charge of the liver is attributable to the more rapid flux of intermediary metabolism in the enhanced ADP-phosphorylating reactions by mitochondria, owing to an elevated level of insulin available to the hepatic cells.

Adenine Nucleotides↗
PubMed1976

Effect of insulin on mitochondrial oxidative phosphorylation and energy charge of the perfused guinea pig liver.

The effect of insulin was investigated in the isolated guinea pig liver perfused with Krebs-Ringer bicarbonate buffer containing red blood cells and albumin. In the mitochondria isolated from livers perfused with 10 units of insulin per hour, the phosphorylative activity with glutamate as a substrate increased to about 160 per cent of control 60 minutes after the beginning of perfusion (p less than 0.01). Such an enhanced phosphorylative activity was accompanied by increases in the respiratory control ratio, state 3 respiration, and P/O ratio. On the other hand, in the liver perfused with insulin, the levels of the energy charge and adenine nucleotide quotient increased to a significant degree as compared to the liver without insulin (p less than 0.01 and p less than 0.05, respectively). It is suggested that insulin plays an important role as a portal factor in regulating mitochondrial oxidative phosphorylation and the levels of the phosphorylated adenine nucleotides.

Adenosine Diphosphate↗
PubMed1974

Clinical application of cytochrome a(plus a3) assay of mitochondria from liver specimens: an aid in determining metabolic tolerance of liver remnant for hepatic resection.

Measurement of cytochrome a(+a(3)) contents in liver mitochondria was made on 52 biopsy specimens of patients with liver tumor. Patients having higher cytochrome a(+a(3)) contents in mitochondria from remaining liver than those of normal human liver mitochondria could survive well major liver resections whether or not associated with liver cirrhosis. However, patients with cytochrome a(+a(3)) contents less than 0.5 x 10(-10) moles per mg protein showed a high rate of postoperative complication (80%) and death (40%) in spite of minor operation. In routinely used liver function tests such as serum albumin, A/G ratio, SGOT, total bilirubin, prothrombin time, BSP and TTT, there were no significant differences between patients with cytochrome a(+a(3)) contents more than 0.5 x 10(-10) moles per mg protein and those less than 0.5. The results indicate that routine laboratory studies do not have much diagnostic value in estimation of a marked decrease of mitochondrial cytochrome a(+a(3)) contents. It is suggested that the measurements of cytochrome a(+a(3)) of the remnant liver should be done prior to a contemplated major resection.

Adolescent↗