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Query: UMLS:C0038187 (starvation)
 24,951 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Starved cells of Candida utilis accumulated Zn2+ by two different processes. The first was a rapid, energy- and temperature-independent system that probably represented binding to the cell surface. The cells also possessed an energy-, pH-, and temperature-dependent system that was capable of accumulating much greater quantities of the cation than the binding process. The energy-dependent system was inhibited by KCN, Na2HAsO4, m-chlorophenyl carbonylcyanide hydrazone, N-ethylmaleimide, EDTA and diethylenetriaminepenta-acetic acid. The system was specific inasmuch as Ca2+, Cr3+, Mn2+, Co2+ or Cu2+ did not compete with, inhibit, or enhance the process, Zn2+ uptake was inhibited by Cd2+. The system exhibited saturation kinetics with a half-saturation value of 1.3 muM and a maximum rate of 0.21 (nmol Zn2+) min(-1) (mg dry wt(-1)) at 30 degrees C. Zn2+ uptake required intact membranes since only the binding process was observed in the presence of nystatin, toluene, or sodium dodecyl sulphate. Cells did not exchange recently accumulated toluene, or sodium dodecyl sulphate. Cells did not exchange recently accumulated 65Zn following the addition of a large excess of non-radioactive Zn2+. Similarly, cells pre-loaded with 65Zn did not lose the cation during starvation, and efflux did not occur when glucose and exogenous Zn2+ were supplied after the starvation period. Efflux was only observed after the addition of toluene or nystatin, or when cells were heated to 100 degrees C. Cells fed a large quantity of Zn2+ contained a protein fraction resembling animal cell metallothionein. In batch culture, cells of C. utilis accumulated Zn2+ only during the lag phase and the latter half of the exponential-growth phase.
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PMID:Accumulation and storage of Zn2+ by Candida utilis. 0 25

The rate of individual ribosomal protein synthesis relative to total protein synthesis has been determined in Escherichia coli rel+ and rel- cells, under valyltRNA deprivation. These strains have a temperature-sensitive valyl-tRNA synthetase. Starvation was obtained following transfer to the cells to non-permissive temperature. Ribosomal proteins were obtained by treatment of either total lysates of freeze-thawed lysozyme spheroplasts or ammonium sulphate precipitate of ribosomes, with acetic acid. Differential labelling of the ribosomal proteins was observed in both strains: proteins from the rel+ strain appear more labelled than those from the rel- strain, the rate of labelling of individual proteins being about the same in both strains. Moreover ribosomal proteins were found as stable during starvation as total protein. It is thus concluded that in starving cells individual ribosomal proteins are not synthesized at equal rates. This indicates that the synthesis of ribosomal proteins is not only under the control of the rel gene.
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PMID:On the control of ribosomal protein biosynthesis in Escherichia coli. I. Studies on ribosomal protein biosynthesis in amino acid-starved cells. 32 Oct 26

The growth of the eucaryotic microorganism Dictyostelium discoideum in liquid culture was completely inhibited by the aspartic acid analog hadacidin (N-formylhydroxyamino-acetic acid). Growth arrest occurred both in chemically defined medium and in complex growth medium containing aspartic acid and AMP precursors such as adenine and adenosine. Although these compounds could not overcome the effect of hadacidin, growth was restored if cells were washed and resuspended in fresh growth medium. Additional experiments showed that D. discoideum contains adenylosuccinate synthetase, the enzyme which catalyzes the synthesis of adenylosuccinate from IMP, aspartic acid, and GTP in the de novo biosynthesis of purines. A partially purified preparation of this enzyme was obtained, and the effect of hadacidin on its activity was studied. We found that maximum inhibition of the D. discoideum activity occurs at a ratio of aspartic acid to hadacidin of 5:1, suggesting that the affinity of the drug for this enzyme is less than for the enzyme from rabbit muscle and plants but greater than for that from Escherichia coli. The effect of the drug can be overcome by a 10-fold excess of aspartic acid, suggesting that the drug acts as a competitive inhibitor. A comparison of the adenylosuccinate synthetase activity levels at various stages of growth showed that its specific activity decreases about 60% as cells enter the stationary growth phase, and decreases about 75% after starvation for 2 h. Further studies showed that in cells treated with hadacidin the rate of uptake of exogenous nutrients is reduced about 75% and that these cells are more resistant to rupture by osmotic shock. While the results of this study are consistent with the proposal that growth arrest is contingent upon inhibition of adenylosuccinate synthetase activity, they also suggest that, as a consequence of this inhibition, some physiological properties of the cell have been altered.
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PMID:Effect of hadacidin on growth and adenylosuccinate synthetase activity of Dictyostelium discoideum. 56 51

1. Homogenates of rat epididymal fat pad, heart, kidney, lactating mammary gland, liver, skeletal muscle and small intestinal mucosa have been partitioned into a particulate and supernatant fraction. With reliable marker enzymes for the mitochondrial matrix and the cytosol: propionyl-CoA carboxylase and pyruvate kinase, the distributions of the acyl-CoA synthetase activities measured at 1 and 10 mM C2, C3 and C4 over mitochondria and cytosol have been calculated. From these values an estimate was made of the K0.5 of the fatty acids. 2. A distinct fatty acid-activating enzyme was assumed to be present in one of the compartments when that fatty acid was activated with a K0.5 less than or equal to 1.5 mM in an amount of greater than 13% of the total cellular activity. Adipose tissue, gut, liver and mammary gland, all organs of a high lipogenetic capacity, contained a cytosolic acetyl-CoA synthetase. At 1 mM acetate 60, 31, 77 and 83% of the total cellular activities in these organs were cytosolic in nature, with activities of 0.021, 0.32, 0.37 and 1.16 mumol C2 activated per min per g wet weight, respectively. 3. Mitochondrial acetyl-CoA and butyryl-CoA synthetases were found in adipose tissue, gut, heart, kidney, mammary gland and muscle. They were absent in liver. Adipose tissue and liver contained a mitochondrial propionyl-CoA synthetase with activities at 1 mM C3 of 0.014 and 1.50 mumol C3 activated per min per g wet weight, respectively. 4. At 1 mM, C2 was activated with decreasing rates by kidney, heart, mammary gland and gut (7.6-1.0 mumol C2 activated per min per g wet weight). C3 (1 mM) activation was about equal (1.6-1.9 mumol C3 activated per min per g wet weight) in liver, kidney and heart. C4 (1 mM) was activated with decreasing rates by heart, liver, kidney and gut (4.0-0.5 mumol C4 activated per min per g wet weight) in the order given. 5. The influence of the isolation method and the diet on fatty acid activation in small intestinal mucosal scrapings have been studied. To demonstrate the existence of cytosolic acetyl-CoA synthetase in fed animals a pre-treatment of everted intestine by low amplitude vibration has been found essential. Also C16 activation was highly (95%) decreased in a non-pre-vibrated preparation. 24 h starvation lowered cytosolic C2 and total C16 activation by 90 and 80%, respectively. Refeeding of starved rats with a balanced fat-free diet, and not with sucrose only, gave the same cytosolic C2 and total C16 activation as normally fed rats. 6. In guienea-pig heart, kidney, liver and muscle about the same partitions have been found as in the respective rat organs. The acetate activation in liver was factor 6 lower. Acetate and butyrate activation in guinea-pig muscle was much higher (6 and 37 times, respectively).
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PMID:Organ and intracellular localization of short-chain acyl-CoA synthetases in rat and guinea-pig. 120 46

In phenylalanine administered rat, tryptophan chiefly metabolized to xanthurenic acid and in nicotinic acid administration to 5-hydroxy indole acetic acid mainly. MAO reaction inhibited by quinoline compound and the inhibition of kynurenine aminotransferase activity through the injection of epinephrine or serotonin were observed. And also the induction of tryptophanpyrrolase in starvation was discussed.
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PMID:Tryptophan metabolism in various nutritive conditions. 124 91

Two models of food deprivation were used to study feeding behavior: starvation and dietary restriction. Rats starved for 3 days had decreased protein intake during the first 2 days of refeeding followed by increased carbohydrate consumption compared to controls. During refeeding, total intake was initially low compared to controls. In a second starvation study of similar design, brain tissues [raphe, ventromedial hypothalamus (VMH)] and sera were collected for analysis before refeeding and on day 2 of refeeding. Starved and starved-refed rats had increased serum beta-hydroxybutyrate versus controls. In rats restricted for 5 days (5 g/day), total food intake was increased immediately and was characterized primarily by carbohydrate intake. Serotonin levels in the raphe were decreased in restricted rats and 5-hydroxyindole acetic acid (5-HIAA) increased in restricted-refed rats. Restriction caused an increase in blood levels of beta-hydroxybutyrate and a decrease in insulin and glucose compared to controls. Fat selection remained low throughout all studies. The data suggest that starvation and food restriction elicit different patterns of macronutrient selection upon refeeding.
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PMID:Effect of starvation or restriction on self-selection of macronutrients in rats. 155 42

Male rats kept in a running wheel developed hyperactivity when food was restricted. Highest activity occurred around noon when food was given. Semistarved sedentary and ad lib fed sedentary and running rats served as controls. Five-hydroxyindole-acetic acid (5-HIAA) in the medial basal hypothalamus was lowest in the sedentary ad lib fed group. Running significantly increased 5-HIAA. Starvation likewise increased 5-HIAA. This effect was further enhanced by hyperactivity. When the circadian rhythm of serotonin (5-HT) and 5-HIAA was studied in the hypothalamus, a minimum of 5-HT as seen in semistarved sedentary and running rats around feeding time (noon). At this time 5-HIAA reached a maximum in the semistarved running rats while semistarved sedentary and ad lib fed rats showed no circadian pattern of 5-HIAA. These data indicate that serotonin turnover in the medial basal hypothalamus is increased as a consequence of semistarvation and hyperactivity.
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PMID:The influence of semistarvation-induced hyperactivity on hypothalamic serotonin metabolism. 172 Aug 94

400 MHz 1H NMR spectroscopy was used to analyze methyl group-containing metabolites in perchloric acid extracts of livers of rats treated with carbon tetrachloride or fed with ethanol-containing liquid diets, and sacrificed with carbon dioxide anoxic euthanasia or pentobarbital euthanasia (with or without 12-18 hour fasting). In all cases, coenzyme A was detected using 1H NMR spectroscopy, but at higher levels for chronic ethanol-treated rats. Propionate was also detected in livers 6 hours after treatment with carbon tetrachloride. The assignments of the 1H NMR resonances in a spectrum of biological origin to these two metabolites have not been previously reported. Another unusual metabolite, 1,2-propanediol, was also observed in dramatically elevated levels in starved rats. The methyl groups for coenzyme A, propionate, and 1,2-propanediol have 1H NMR chemical shifts at 0.73 and 0.87 ppm, 1.18 ppm, and 1.14 ppm (from tetramethylsilane) respectively. In addition to the above mentioned resonances, glutamine, glutamate, proline, acetate, leucine, alanine, lactate, ethanol, beta-hydroxybutyrate, and valine were also observed in the 0.5-2.3 ppm methyl region of the 1H NMR spectra. Biochemical changes were also observed in these latter metabolites. beta-Hydroxybutyrate was increased by chronic ethanol administration; this increase was exacerbated by starvation. Alanine was decreased by chronic ethanol administration. Acetate was increased by chronic ethanol administration except when glycerol was added to the liver or when the rat was starved. We also observed an unassigned triplet at 0.81 ppm, and its appearance seems to be correlated with that of 1,2-propanediol.
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PMID:1H NMR analyses of methyl group-containing metabolites in rat liver extracts--effects of starvation, anoxia, acute glycerol and carbon tetrachloride treatment and chronic ethanol administration on hepatic metabolism. 181 3

1. To test the hypothesis that the colon contributes significantly to venous plasma acetate concentrations, experiments were carried out in healthy volunteers and ileostomy patients. 2. Fasting plasma acetate levels were measured in 10 ileostomy patients and compared with those in 21 control subjects. Values in ileostomy patients (21.3 +/- 0.8 mumol/l) were significantly lower than in control subjects (48.0 +/- 4.2 mumol/l). 3. Plasma acetate concentration was estimated in eight healthy volunteers during 108 h of continuous fasting. Acetate concentrations rose significantly from 12 h (43.9 +/- 4.4 mumol/l) to 108 h of starvation (114.0 +/- 15.6 mumol/l) and fell back to normal fasting values on refeeding and another 12 h fast (44.3 +/- 4.7 mumol/l). 4. When colonic fermentation was stimulated after oral ingestion of 10 g of lactulose, the plasma acetate concentration increased significantly (from 44.0 +/- 7.4 to 114.4 +/- 16.2 mumol/l) in seven healthy control subjects. This rise was not affected by concomitant dosage of metronidazole. 5. These data suggest that there are at least two major sources of acetate in man, an endogenous source and the colon which probably becomes more important when fermentation of carbohydrate is occurring.
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PMID:The contribution of the large intestine to blood acetate in man. 184 71

Previously we found that Drosophila melanogaster lines selected for increased desiccation resistance have lowered metabolic rate and behavioral activity levels, and show correlated responses for resistance to starvation and a toxic ethanol level. These results were consistent with a prediction that increased resistance to many environmental stresses may be genetically correlated because of a reduction in metabolic energy expenditure. Here we present experiments on the genetic basis of the selection response and extend the study of correlated responses to other stresses. The response to selection was not sex-specific and involved X-linked and autosomal genes acting additively. Activity differences contributed little to differences in desiccation resistance between selected and control lines. Selected lines had lower metabolic rates than controls in darkness when activity was inhibited. Adults from selected lines showed increased resistance to a heat shock, 60Co-gamma-radiation, and acute ethanol and acetic acid stress. The desiccation, ethanol and starvation resistance of isofemale lines set up from the F2s of a cross between one of the selected and one of the control lines were correlated. Selected and control lines did not differ in ether-extractable lipid content or in resistance to acetone, ether or a cold shock.
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PMID:Selection for increased desiccation resistance in Drosophila melanogaster: additive genetic control and correlated responses for other stresses. 250 23


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