Localization of TCA cycle dehydrogenases in the mitochondria

The site of localization of TCA cycle dehydrogenases in mitochondria has been investigated by observing the dehydrogenase activities and fine structure of the fractionated samples after freezing and thawing or sonication of beef heart and rat liver mitochondria. 1. In the sonicated mitochondria, activities of malic and isocitric dehydrogenases were highest in the supernatant fraction centrifuged at 198,000 x g for 60 minutes, while the specific activity of a-ketoglutaric dehydrogenase was higher in the fluffy or residue fraction. The distribution of the activity of pyruvic dehydrogenase was similar to that of a-ketoglutaric dehydrogenase. 2. In a sucrose density gradient fractionation of the fluffy fraction obtained by centifugation of sonicated mitochondria at 198, 000 x g for 60 minutes, the activities of malic and pyruvic dehydrogenase were observed in the top (or low density) layer in the form of fine particles, while that of a-ketoglutaric dehydrogenase was observed in the middle (or medium density) layers in the form of aggregates of fine particles and membranous fragments. 3. In the samples fractionated after freezing and thawing of mitochondria, which were considered to be a relatively mild disruption, the specific activity of a-ketoglutaric dehydrogenase was higher in the residue (submitochondria) fraction than that in the supernatant fraction (centrifuged at 144,000 x g, 30 minutes), and the activity of malic dehydrogenase still remained significantly high in the residue fraction. 4. It was deduced that the TCA cycle dehydrogenases could be localized in the matrix of the mitochondria by a loose binding to the inner membrane.</p

Histochemical Studies on the Nervous and Humoral Regulation of Lipids and Carbohydrate Metabolism

The purpose of the present study is to reveal the precise mechanism of nervous and humoral regulations of lipid and carbohydrate metabolisms in the adipose tissues. Histochemical and biochemical observations were made on the innervated and denervated interscapular brown adipose tissues and partly on the liver and adrenal cortex of male mice during starvation with or without carbohydrate introduction with special consideration to the changes of the lipid and glycogen contents and to the activities of several important enzymes as well as to pH values in the tissues. In a state of absolute starvation, the animals died in a few days showing a gradual discharge of stored lipids from the innervated brown adipose tissues, while in the denervated tissues the stored lipids increased gradually even in a state of slight or moderate starvation as well as in the cases of normally fed animals. The increase of lipids continued before the stage of severe starvation and the stored lipids being rapidly discharged became nil at the terminal stage of life. Introduction of glucose into starved animals caused also a more marked deposition of glycogen in the denervated than in the innervated tissues in proportion to the degree of starvation, although it did not cause the deposition in both tissues at the terminal stage of life. These facts represent that the nervous regulation is essential for the mobilization of lipids and carbohydrates from this tissue. Adrenalectomy also caused the death of animals within a few days with a gradual decrease of depot lipids. In this case denervation likewise caused a marked depositon of lipids in the brown adipose tissues, showing a sudden escape of lipids at the end of life. Experiments on transplanted adipose tissues taken from the animals at the terminal stage of starvation, proved that the tissue cells retain the ability to deposit lipids until the end of life. Chemical estimation elucidated that the serum glucose and lipids fall markedly at the terminal stage of life. The innervated tissues showed increased activities of succinic dehydrogenase, alkaline phosphatase, ATPase and lipase during starvation with a gradual discharge of lipids. Glucose injection increased the degree of the activities of all these enzymes, though in the terminal stage of starvation the ATPase activity declined again. The activity of total cholinesterase declined slightly in severe starvation. The pH value fell gradually with the progress of starvation. On the other hand, in the denervated tissues the activity of succinic dehydrogenase fell with an increased deposition of lipids, though in the final stage of starvation the activity rose with the discharge of lipids; while the activities of phosphatase, ATPase and lipase rose during starvation and total, unspecific and specific cholinesterase activities declined slightly. The pH value in the denervated tissues rose slightly during mild starvation and fell markedly in severe starvation. Observations proved that the activities Df these enzymes and pH, which are under the control of the autonomic nervous system, have close relationships to the deposition and the discharge of lipids and glycogen from the adipose tissues, and that the rapid discharge of lipids from the denervated tissue at the terminal stage of life is an expression of the onesided progress of oxidative process which may mean a complete loss of regulation of metabolism.</p

Association between serum inorganic phosphorus levels and adverse outcomes in chronic kidney disease: The Fukushima CKD Cohort study

博士（医学）福島県立医科大

Cytochemicar demonstra­tion of the sites of activity of the terminal electron transport system with the electron microscope

In an attempt to pursue the relationship of the fine structure of a cell to the biochemical function, the author at first tried to demonstrate cytochemically the actual sites of activity of enzymes in the terminal electron transport system involved in energy production with the use of the electron microscope. Namely, cytochemical reactions were performed by using potassium tellurite, a heavy metal salt, and then the author succeeded in the electron microscopic detection of the enzymes by freezing-drying method and by means of formalin fixation, strong reducing agents and osmium tetroxide fixation. As the results the author has been able to verify that the reactions of the enzymes belonging to the terminal electron transport system are found localizing in the mitochondria being arranged fairly densely and continuously on the critae and partially on the membrane, although some differences in the grade of the activity are found in each mitochondria even in one cell and a marked difference between the mitocndria belonging to the different kinds of cells. Furthermore, it has been clarified that the activity of the endogenous dehydrogenase system (mainly DPNH- or TPNH-dehydrogenase and others) is chiefly strong in cristae, and that the succinoxidase system exists both in cristae and membrane.</p