Biomedical subjects
Publications and source records attributed to W Gerok.
Two patients with complicated acute pancreatitis are demonstrated. Sonographic factors are compared to laboratory and clinical findings. Ultrasound can add relevant information for classification and thereby supply an indication for surgery in patients with acute pancreatitis. This is especially true since laboratory classification of the grade of the disease is as yet not generally accepted.
An isoenzyme of creatine kinase [ATP: creatine N-phosphotransferase, EC 2.7.3.2] was isolated in pure, crystalline form from mitochondria of human heart muscle. The enzyme has a molecular weight of 84,000 and consists of two subunits with identical molecular weight, each containing two reactive sulfhydryl groups. The enzyme has a specific activity of 15 +/- 2 U/mg in the direction of creatine phosphate synthesis at optimum pH of 8.7 and of 45 +/- 5 U/mg in the direction of ATP synthesis at optimum pH of 6.7. Mitochondrial creatine kinase has Michaelis constants of 1.70 mM for MgATP2-, 8.00 mM for creatine, 0.15 mM for MgADP-, and 3.00 mM for creatine phosphate. The mitochondrial enzyme differs from the other creatine kinase isoenzymes, i.e. from muscle (CK-MM), brain (CK-BB), and their hybrid form (CK-MB) in (I) its amino acid composition and its amino terminal amino acid sequence, (II) its electrophoretic mobility, and (III) its immunological properties. It thus constitutes a fourth isoenzyme of creatine kinase. By analogy to CK-MM, CK-BB, and CK-MB, the mitochondrial isoenzyme was designated as CK-MiMi.
Addition of nitrofurantoin to isolated perfused rat liver leads to an inhibition of 14CO2 production from [1-14C]pyruvate, 2-oxo-[1-14C]isocaproate and 2-oxo-[1-14C]isovalerate, indicating a decreased flux through the corresponding mitochondrial 2-oxo-acid dehydrogenases. This is in agreement with a decreased tissue level of the active (dephospho)form of pyruvate dehydrogenase in presence of nitrofurantoin. 2) Evidence is presented for an inhibition of the monocarboxylate translocator in the mitochondrial membrane during addition of nitrofurantoin by comparing the effects of alpha-cyanocinnamate as a transport inhibitor with those of nitrofurantoin. 3) It is concluded that nitrofurantoin-induced hepatocyte toxicity may include mitochondrial effects due to decreased oxo-acid dehydrogenase flux.
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To elucidate the possible role of portosystemic shunting on zinc and vitamin A deficiency which has been described in patients with cirrhosis of the liver, a study on 37 hospitalized patients with liver cirrhosis was performed. Patients with surgical portosystemic shunt were found to have a significantly lower levels of zinc, vitamin A and retinol-binding protein (RBP) than controls and patients with cirrhosis without shunt. Patients with portal hypertension--considered to have spontaneous shunting--also has lower levels than those without this symptom. A significant correlation between zinc and vitamin A and RBP levels, respectively, was found. Also an increased renal zinc output was demonstrated. An influence of portosystemic shunting on zinc deficiency and subsequent vitamin A deficiency by decreased RBP release is concluded. The importance of these metabolic disorders for clinical symptoms is discussed.
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Epithelia can be classified as "leaky" and "tight epithelia" due to their conductive properties and their modes of solute transport. Both the proximal segment of the nephron and the intestinal tract are "leaky" whereas the distal nephron and the colon are "tight". Consequently, inborn errors and exogenous disorders of solute transport often involve both the proximal tubule and the small intestine. In addition, effects on ion and water transport in the distal nephron closely resemble those in the large intestine. Models of solute transport in leaky and tight epithelia are presented employing porter systems known in mammalian tissues. These porter systems are discussed as possible sites of transport defects and as targets for pharmacological agents.
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Microsomal UDP-glucuronosyltransferase activity toward chenodeoxycholic acid and testosterone has been isolated from rat liver and appears to be homogeneous in sodium dodecyl sulfate gel electrophoresis and polyacrylamide gradient gel electrophoresis. The conjugating activities toward chenodeoxycholic acid and testosterone co-purified and showed identical mobilities in disc gel electrophoresis, indicating that chenodeoxycholic acid and testosterone are glucuronidated by a single form of enzyme. UDP-glucuronosyltransferase activities toward estrone, bilirubin, 4-nitrophenol, and morphine did not co-purify with the activity toward chenodeoxycholic acid and testosterone and were not detectable in the pure enzyme in the presence or absence of phospholipids. In addition to glucuronic acid conjugation, the enzyme is able to catalyze galacturonic acid conjugation of chenodeoxycholic acid and testosterone. The enzyme has a subunit Mr approximately 54,000 and in the presence of the stabilizing detergent chenodeoxycholic acid, it appears to exist as an aggregate with an apparent Mr = 318,000 as estimated by gel filtration and 316,000 by polyacrylamide gradient gel electrophoresis.
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1. Photoaffinity labelling of a subfraction of plasma membranes of rat liver, enriched with sinusoidal surfaces, with the sodium salts of (3 beta-azido-7 alpha,12 alpha-dihydroxy-5 beta-cholan-24-oyl)-2-amino[2-3H(N)]ethanesulfonic acid, (7,7-azo-3 alpha,12 alpha-dihydroxy-5 beta-cholan-24-oyl)-2-amino[2-3H(N)]ethanesulfonic acid and (11 xi-azido-12-oxo-3 alpha,7 alpha-dihydroxy- 5 beta-cholan-24-oyl)-2-amino[2-3H(N)]ethanesulfonic acid resulted with each derivative in a clear covalent incorporation of radioactivity into polypeptides with the apparent molecular weights of 67,000, 52,000, 48,000, 43,000 and about 20,000. 2. Photoaffinity labelling of a membrane subfraction predominantly composed of bile canalicular membranes by the photolabile derivatives of the conjugated bile salts also showed covalent incorporation of radioactivity into polypeptides of the same apparent molecular weights as with the subfraction enriched with the sinusoidal membranes. 3. The extent of photoaffinity labelling of the different membrane polypeptides is dependent upon the photolabile bile-salt derivative used. However, with each of the photolabile derivatives the relative ratio of the labelling of the different membrane polypeptides was similar for both membrane subfractions. Provided that the uptake as well as the secretion of bile salts by hepatocytes are carrier-mediated processes, this suggests the participation of the same polypeptides in both processes.
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