K. Honjo

Dietary response of various key enzymes related to glucose metabolism in normal and diabetic rat liver

Abstract With normal rats, administration of a high glycerol diet for 3 days produces a great increase in the activities of various key enzymes involved in glucose utilization in the liver. These include glucokinase (EC 2.7.1.12), pyruvate kinase (EC 2.7.1.40), glucose-6-phosphate dehydrogenase (EC 1.1.1.49), ATP citrate lyase (EC 4.1.3.8) and acetyl-CoA carboxylase (EC 6.4.1.2). Administration of a high glycerol diet to diabetic animals also causes a marked induction of all these enzymes, except glucokinase and glucose-6-phosphate dehydrogenase, in the liver. The latter two enzymes show little response to glycerol feeding in the diabetic state. The induction of pyruvate kinase nd ATP citrate lyase by glycerol feeding is almost completely abolished by actinomycin D treatment in both normal and diabetic rats. The elevated activities of glucose-6-phosphatase (EC 3.1.3.9) and l -serine dehydratase (EC 4.2.1.13) in diabetic liver are not lowered but rather increase on feeding glycerol. A possible explanation for these results is presented, especially in relation to the action of insulin.

CITRIC ACID METABOLISM IN PERIODONTOSIS.

Abstract The citric acid content in blood is apparently elevated in patients with diffuse atrophy of the alveolar bone (periodontosis). In the periodontosis cases, the amount of citric acid excreted in urine during 2 hr after intravenous administration of sodium citrate is significantly increased in comparison with that of normal controls. It is confirmed that disturbed metabolism of citric acid exists in many patients with periodontosis.

Alkaline and acid phosphatase activities in the gingiva and alveolar bone in scurvy.

Abstract Techniques for measuring the enzyme activity of alkaline and acid phosphatases in the gingiva and alveolar bone of guinea pigs are described. Assays of both enzymes were also carried out for liver, kidney, small intestine and femoral cortex. When the activity of alkaline phosphatase was expressed on the basis of unit weight of wet tissue, gingiva and small intestine showed a high value, kidney and alveolar bone an intermediate one, and femoral cortex and liver remarkably low levels. For alkaline phosphatase expressed on the basis of extracted protein, alveolar bone and gingiva, respectively, possessed about 560 and 90 times higher activity than liver which had the lowest value of all tissues studied. When acid phosphatase activity was expressed as units per weight of wet tissue, gingiva and liver showed a high level, kidney and small intestine being almost as high, while a remarkably low level was detected in alveolar bone and femoral cortex. The activity expressed on the basis of extracted protein was almost identical for liver, kidney, femoral cortex and small intestine. Gingiva and alveolar bone had approximately 2.5 and 1.4 times greater activity than liver, respectively. The alkaline phosphatase activity of gingiva, alveolar bone and femoral cortex decreased strikingly after 3 weeks of scorbutic regime. No significant change was found in liver and kidney, though small intestine showed a slight decrease. The acid phosphatase activity of gingiva, alveolar bone, femoral cortex, small intestine and liver showed a significant increase in scurvy, but kidney did not exhibit a significant change.

Citric acid metabolism in scurvy

Abstract Aconitase and TPN-linked iso citric dehydrogenase activities in the supernatant fraction of the gingiva and alveolar bone of scorbutic guinea pigs were evaluated. The activities of both enzymes in the heart, liver, kidney, adrenal gland, pancreas, spleen and femoral cortex were also studied. The aconitase activity of the kidney, alveolar bone, femur cortex and heart decreased to about 75 per cent of the normal value after 3 weeks of scorbutic regime. However, the other tissues did not exhibit significant changes. Elevated citrate level was also found in kidney, alveolar bone and femur cortex in which the aconitase activity was markedly decreased. Prolonged administration of insulin to scorbutic animals restored both the depressed aconitase activity and the elevated citrate content in the kidney and bone tissues significantly to normal level. No significant change in the activity of iso citric dehydrogenase was observed in any of the tissues of scorbutic animals.

Isocitric dehydrogenase activity in the gingiva and alveolar bone of the guinea pig

Abstract A technique for measuring the enzyme activity of TPN-linked isocitric dehydrogenase in the gingiva and alveolar bone of normal guinea pigs has been described. The enzyme activity in the heart, kidney, liver and femur cortex were also determined as controls. When enzyme activity was expressed on the weight of the wet tissue, liver, heart and kidney showed a high value, gingiva a relatively low one, and alveolar bone and femur cortex remarkably low levels. The activities expressed on the basis of content of extracted protein were also high for heart, kidney and liver, those of alveolar bone, femur cortex and gingiva were approximately equal and only some 10 per cent of the level in the more active tissues.

Aconitase and Fumarase Activity in Periodontal Tissues

Aconitase mediates the establishment of an equilibrium between citric, cis-aconitic and d-isocitric acids, and fumarase catalyzes the equilibrium between fumaric acid and 1-malic acid. Cis-aconitic acid and fumaric acid are intermediates in the main pathway of substances oxidized through the tricarboxylic acid cycle. Compounds such as cisaconitic acid and fumaric acid with an unsaturated C = C linkage have a marked absorption in the ultraviolet range. This property can be utilized in a spectrophotometric test, measuring appearance and disappearance of these substances in the course of enzymatic reactions. Racker1 described a rapid and convenient spectrophotometric method for determination of considerably lower activity of both aconitase and fumarase in biological fluids. Recently, Beutler and Yen,2 and Tanaka and Valentine3 have demonstrated the aconitase activity in human blood cells by utilizing a modification of Rackers method. Fumarase activity of human blood cells has been also determined by Tanaka and Valentine.4 The test has been applied to calcified tissues by Reen,5 who estimated the activity of aconitase in rabbit and dog femur. There are no reports to our knowledge of these activities in periodontal tissues. In this paper the activity of both aconitase and fumarase in gingiva and alveolar bone of guinea pigs was selected for evaluation. The activities of these enzymes in liver, heart, kidney, adrenal gland, pancreas, and femur cortex were also studied.

Citrate Synthase Activity in Periodontal Tissues

SYNOPSIS IN INTERLINGUA ACTIVITATE DE SYNTHASE DE CITRATO IN Tissu PERIODONTAL.—Con le utilisation del sensibile e convenibile essayo a fissura per ester thiolic, le activitate de synthase de citrato (EC 4.1.3.7; oxaloacetato-lyase de citrato) esseva determinate in le fractiones supematante de gingiva, osso alveolar, e altere tissus de porco de India. Cortice de femore, osso alveolar, gingiva, hepate, e ren possedeva approximativemente 1/60, 1/33, 1/24, 1/12, e 1/4, respectivemente, le activitate medie per mg de extrahite proteina cardiac. Le activitate exprimite a base de unitates de peso de tissu humide esseva etiam le plus alte pro le corde. Illo de osso alveolar e de gingiva esseva approximativemente 1/440 e 1/40, respectivemente, del correspondente valor trovate pro le corde.

Malic Dehydrogenase Activity in the Gingiva and Alveolar Bone of the Guinea Pig

Malic dehydrogenase is an enzyme associated with the tricarboxylic acid cycle, catalyzing the reversible reaction between L-malate and oxalacetate. This enzyme requires diphosphopyridine nucleotide (DPN) as a hydrogen acceptor. Much attention has been devoted to determine the activity of this enzyme in various tissues of animals. In periodontal tissues, the enzyme activity has been determined by B. Eichel and A. Shahrik (Advances in Oral Biology, 1:140-53, 1964) in human gingiva, whereas little