Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0038187 (starvation)
 24,951 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Intraperitoneal administration of a single dose of 1,1-dichloroethylene (DCE) to C57 B1/6N mice (125 mg/kg) caused a selective 6- to 10-fold increase in renal microsomal 7-ethoxyresorufin O-deethylase ( EROD ) and 7-ethoxycoumarin O-deethylase ( ECOD ), without affecting benzo[a]pyrene hydroxylase activity (AHH) or total microsomal cytochrome P-450 content. The observed increases did not result from in vitro activation of the enzymes or from any analytical artifact. Moreover, studies with actinomycin D and cycloheximide demonstrated that the increases resulted from de novo enzyme synthesis. Maximal enzyme induction was observed after a DCE dose of approximately 125 mg/kg, and the induced enzyme decayed rapidly, returning to control levels in about 3 days. Compared to female mice, male mice had higher basal levels of renal EROD and ECOD and were more responsive to the inductive effects of DCE; this correlated with corresponding differences in microsomal cytochrome P-450 levels. Starvation of mice for 24 or 48 hr increased renal EROD and ECOD activities in both male and female mice, but not the extent observed after DCE. The present results support the view of multiple renal cytochrome P-450 isozymes.
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PMID:Selective induction of renal microsomal cytochrome P-450-linked monooxygenases by 1,1-dichloroethylene in mice. 661 Apr 21

The microsomal preparation from the lactating bovine mammary tissue was solubilized by treatment with nonionic detergent, NP-40, at a protein/detergent ratio of 1.5:1 and a detergent concentration of 0.5%. Following centrifugation at 147000 X g for 120 min, the supernatant fraction was incubated with labeled sugar nucleotides, GDP-Man and UDP-GlcNAc. It was found to synthesize a series of lipid-linked saccharides up to (Man)5-(GlcNAc)2. The solubilized glycosyltransferases retained up to about 60% of the activity after two weeks of storage at 4 degrees C. The biosynthesis of glycolipids was stimulated by a mixture of lipids obtained by extracting the mammary microsomes with CHCl3/CH3OH (2:1). A labeled lipid-linked tetrasaccharide of the structure Man alpha 1----3 Man beta----GlcNAc beta----GlcNAc was isolated by labeling baby hamster kidney cells with [2-3H]mannose under conditions of glucose starvation followed by extraction of the cells with CHCl3/CH3OH (2:1) and separation of the lipids by high-performance liquid chromatography. When this lipid-linked tetrasaccharide was incubated with the solubilized bovine mammary microsomes and GDP-Man, it was elongated to a lipid-linked heptasaccharide having the structure Man alpha 1----2Man alpha 1----2Man alpha 1----3(Man alpha 1----6)Man beta----GlcNAc beta----GlcNAc. The kinetics of the elongation reaction also revealed the intermediary formation of smaller amounts of lipid-linked pentasaccharide and hexasaccharide. The elongation reaction did not require any divalent metal ion and had a broad pH optimum between 6.8 and 7.6. The lack of inhibition of the elongation reaction by EDTA or amphomycin support earlier studies that GDP-Man rather than mannosylphosphoryldolichol, is the direct donor of mannosyl residues for the biosynthesis of glycolipids up to (Man)5(GlcNAc)2. Mannosylphosphorylretinol was ineffective as mannosyl donor for the elongation reaction.
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PMID:Solubilization of mannosyltransferase activities for the biosynthesis of mammary glycoproteins. Elongation of tetrasaccharide-lipid to heptasaccharide-lipid by a solubilized enzyme preparation. 669 9

Male Sprague-Dawley rats and male B6C3F1 mice excreted 5-15% of a tracer dose of [14C]trichloroethylene as 14CO2 within 24 h after ip injection of a single dose in a corn-oil vehicle. The proportion of the dose excreted as CO2 was greater in mice than in rats, but increased in the rats after starvation or pretreatment with phenobarbital. As the dose was increased toward the LD50 level, the proportion excreted as 14CO2 decreased slightly, but this was largely due to increased loss of unchanged trichloroethylene. The excretion of 14CO2 was thus correlated with the expected level of microsomal metabolism of trichloroethylene to an electrophilic intermediate capable of binding to glutathione or macromolecules. Liver protein labeling was observed to be relatively high (10,000-23,000 cpm/mg in the mouse), while DNA labeling was consistently observed to be very low, not allowing identification of any adducts by high-performance liquid chromatography (HPLC). Also, no effect on DNA fragmentation was seen by alkaline sucrose gradient centrifugation after injection of an LD50 dose of trichloroethylene. The ability of trichloroethylene to interact with DNA in vivo was thus observed to be very slight.
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PMID:Metabolism of [14C]trichloroethylene to 14CO2 and interaction of a metabolite with liver DNA in rats and mice. 681 65

Fatty acid activation was examined by assessing the activity of acyl-CoA synthetase (ACS) in microsomal fractions of liver and adipose tissue obtained from swine of various ages. Liver ACS activity increased from ca. 200 to 800 nmol/(minute x g tissue) between birth and 25 days postpartum; enzyme activity generally remained elevated postweaning through 155 days of age. The preweaning hepatic patterns on a wet weight and protein basis were similar, but the wet weight- and protein-based patterns diverged after weaning due to an increase in microsomal protein. As in liver, adipose tissue ACS activity rose rapidly from birth to 25 days of age [20-110 nmol/(minute x g tissue)] but declined to lower levels after weaning. Expression of enzyme activity on a wet weight, protein, or cellular basis revealed similar developmental patterns for adipose tissue. The postweaning fall in adipose tissue ACS activity was partially explained by decreasing cellularity per unit tissue weight. In swine fed equal amounts of isoenergetic-isonitrogenous diets with low or high fat content, hepatic ACS activity tended to increase in pigs fed the high fat diet with no effect of diet on the adipose enzyme. Starvation elevated liver ACS activity, whereas the adipose enzyme activity was marginally decreased.
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PMID:Swine microsomal acyl-CoA synthetase activity: effect of age and diet. 688 26

Mice were found to convert acetone to lactate at appreciable rates. The conversion of acetone to gluconeogenic precursors could provide additional glycolytic intermediates that would allow the more complete utilization of lipid stores and increase survival time during starvation. In mice that were starved for 3 days or were provided with acetone in the drinking water the acetone-metabolizing pathway was induced to levels severalfold normal. Mice heterozygous for obesity-producing mutations, either obese (ob/+) or diabetes (db/+), showed induction of the activity of this pathway to a significantly higher degree than did homozygous normal (+/+) mice of the same strain. This more effective conversion of acetone to lactate exhibited by heterozygous mice could account for their prolonged survival on a starvation regimen compared to that of normal homozygotes. The rate-limiting step in the pathway appears to be the conversion of acetone to a hydroxylated derivative. The enzyme system effecting this conversion is an NADPH-requiring microsomal oxygenase found in the liver.
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PMID:Acetone metabolism in mice: increased activity in mice heterozygous for obesity genes. 692 21

We have examined the interconversion of cortisone (E) and cortisol (F) in rat lung homogenate and microsomal fraction and in the isolated rat lung perfused with Krebs bicarbonate solution containing 4.5% albumin. In the perfused lung the apparent Km was 5.1 microM E and the Vmax was 9 nmol . g(-1) . min-1. The ability of the lung to reduce E to F was enhanced both by 7 days prior exposure of the rat to an ambient temperature of 2 degrees C and by starvation of the rat for 3 days. The activity was inhibited by adrenalectomy and castration of 7 days duration. Whereas little steroid oxidation occurred in the perfused lung, preparations of lung homogenates and microsomal fraction readily reduced or oxidised the 11-position of the corticoid molecule depending on the preponderance of either NADPH or NADP, respectively. We conclude, that the predominance of the reductive reaction in the whole rat lung under physiological conditions reflects the very active pentose-phosphate shunt in the lung, which produces NADPH. We suggest that this ability of the lung to activate E to F may exert a fine control over the arterial concentration of unbound, physiologically active, 11-hydroxylated steroid.
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PMID:The physiological significance of 11 beta-hydroxysteroid dehydrogenase in the rat lung. 695 69

The activities of microvillus aminopeptidase (microsomal, EC 3.4.11.2), dipeptidyl peptidase IV (EC 3.4.14.-), glycyl-leucine dipeptidase (EC 3.4.13.11), proline dipeptidase (EC 3.4.13.9), sucrase (EC 3.2.1.48) and gamma-glutamyl transpeptidase (EC 2.3.2.2) were measured in peroral intestinal biopsies taken from patients with coeliac disease in the acute phase and in remission. A comparison with the amounts of corresponding activities from a reference group showed that all the measured activities were significantly decreased in the acute phase of the disease. In patients in remission only microvillus aminopeptidase and dipeptidyl dipeptidase IV displayed a substantial depression as compared to the reference group. It is suggested that a primary mucosal digestion defect will result in lack of substrate for other intestinal enzymes. This is a situation comparable to starvation and may explain the variation in the grade of restitution for the different enzymes.
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PMID:Intestinal peptidases and sucrase in coeliac disease. 700 82

1. The dependency of product formation on reaction time and on enzyme concentration was studied with certain purified enzymes and liver microsomal mixed-function oxidase system. 2. The product-formation-time relation was estimated with different enzyme and/or substrate concentrations for the reactions limited by diffusion. 3. The kinetic constants of the product-time relations in these diffusion systems have been verified experimentally to give a more specific and detailed characterization of an enzyme system under a variety of physiologic and reaction conditions. 4. The influence of inhibitors and activators in vitro, the effect of enzyme preparation technic, aging, starvation, pretreatment with somatotropic hormone, phenobarbital or 3-methylcholanthrene, and the effect of a tumor were studied. 5. The influence of vitamin C deficiency in guinea pig was also studied.
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PMID:The effect of chemical and physiological factors on the kinetics for product formation as it relates to enzyme activity and concentration, reaction time and to substrate adsorption and affinity. 705 28

Previously we [Sabine & James (1976) Life Sci. 18, 1185--1192] proposed that 'the activity of hepatic beta-hydroxy-beta-methylglutaryl-coenzyme A reductase is critically regulated by the fluidity of its supporting microsomal membrane'. In the present work we examined further this concept of membrane-mediated control, with respect to the specific hypothesis that such control might function as a common mechanism both for the co-ordinated regulation of other enzymes affected by cholesterol feeding and also for the subcellular integration of the several physiological factors known to influence this enzyme's activity. Contrary to earlier expectations, this hypothesis now appears not to hold. We report here that, under those conditions of short-term cholesterol feeding that affected the reductase, a variety of other microsomal enzymes did not display membrane-function interactions, i.e. neither enzymes involved in cholesterol metabolism and also affected by cholesterol feeding (cholesterol 7 alpha-hydroxylase), nor those involved in cholesterol metabolism and not affected by cholesterol feeding (hydroxymethylglutaryl-CoA hydrolase, acyl-CoA:cholesterol acyltransferase), nor those not directly involved in cholesterol metabolism at all (glucose 6-phosphatase). Furthermore, we observed no evidence for the operation of membrane-mediated control of the reductase in other situations known to influence its activity, i.e. starvation, diurnal rhythm, the very early stages of cholesterol feeding and various manipulations in vitro.
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PMID:Membrane-mediated control of hepatic beta-hydroxy-beta-methylglutaryl-coenzyme A reductase. 730 30

The p-hydroxylation of aniline has been traditionally determined by measurement of p-aminophenol (PAP) formation. Comparison of isotopic and colorimetric procedures indicate that the actual amount of aniline metabolized exceeds the among of PAP recovered. Data suggest that enhancement of p-hydroxylation of aniline by acetone, malaoxon and paraoxon may result from inhibition of further metabolism of PAP by the microsomal cytochrome b5-dependent desaturase system. Involvement of the desaturase system is supported by observations that: (a) metabolism of PAP was reduced by starvation and stimulated when starvation was followed by feeding a high carbohydrate diet; (b) enrichment of hepatic microsomes with detergent purified cytochrome b5 decreased the amount of aniline apparently metabolized, as measured by the amount of PAP recovered, and (c) a high correlation occurred between effects of acetone, malaoxon and paraoxon on reoxidation of cytochrome b5 and capacity of these three compounds to enchance aniline metabolism.
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PMID:Inhibition of p-aminophenol metabolism: a possible mechanism of enhancement of aniline hydroxylation. 741 17


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