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)

The spoT gene of Salmonella typhimurium has been identified. Mutations in spoT map between gltC and pyrE at 79 min. The spoT1 mutant has elevated levels of guanosine 5'-diphosphate-3'-diphosphate (ppGpp) during steady-state growth and exhibits a slower than normal decay of ppGpp after reversal of amino acid starvation. The spoT1 mutation elevates his operon expression but is distinct from known his regulatory mutations. Elevated his operon expression in spoT mutants causes resistance to the histidine analogs, 1,2,4-triazole-3-alanine and 3-amino-1,2,4-triazole. These properties of spoT mutants allowed us to identify and characterize additional spoT mutants. Approximately 40% of these mutants are temperature sensitive for growth on minimal medium, suggesting that the spoT function is essential or that excessive accumulation of ppGpp is lethal.
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PMID:Mutations in the spoT gene of Salmonella typhimurium: effects on his operon expression. 389 29

Previous attempts to account for the labelling in vivo of liver metabolites associated with the citrate cycle and gluconeogenesis have foundered because proper allowance was not made for the heterogeneity of the liver. In the basal state (anaesthetized after 24h starvation) this heterogeneity is minimal, and we show that labelling by [14C]bicarbonate can be interpreted unambiguously. [14C]Bicarbonate was infused to an isotopic steady state, and measurements were made of specific radioactivities of blood bicarbonate, alanine, glycerol and lactate, of liver alanine and lactate, and of individual carbon atoms in blood glucose and liver aspartate, citrate and malate. (Existing methods for several of these measurements were extensively modified.) The results were combined with published rates of gluconeogenesis, uptake of gluconeogenic precursors by the liver, and citrate-cycle flux, all measured under similar conditions, and with estimates of other rates made from published data. To interpret the results, three ancillary measurements were made: the rate of CO2 exchange by phosphoenolpyruvate carboxykinase (PEPCK; EC 4.1.1.32) under conditions that simulated those in vivo; the 14C isotope effect in the pyruvate carboxylase (EC 6.4.1.1) reaction (14C/12C = 0.992 +/- 0.008; S.E.M., n = 8); the ratio of labelling by [2-14C]- to that by [1-14C]-pyruvate of liver glutamate 1.5 min after injection. This ratio, 3.38, is a measure of the disequilibrium in the mitochondria between malate and oxaloacetate. The data were analysed with due regard to experimental variance, uncertainties in values of fluxes measured in vitro, hepatic heterogeneity and renal glucose output. The following conclusions were reached. The results could not be explained if CO2 fixation was confined to pyruvate carboxylase and there was only one, well-mixed, pool of oxaloacetate in the mitochondria. Addition of the other carboxylation reactions, those of PEPCK, isocitrate dehydrogenase (EC 1.1.1.42) and malic enzyme (EC 1.1.1.40), was not enough. Incomplete mixing of mitochondrial oxaloacetate had to be assumed, i.e. that there was metabolic channelling of oxaloacetate formed from pyruvate towards gluconeogenesis. There was some evidence that malate exchange across the mitochondrial membrane might also be channelled, with incomplete mixing with that in the citrate cycle. Calculated rates of exchange of CO2 by PEPCK were in agreement with those measured in vitro, with little or no activation by Fe2+ ions.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:[14C]bicarbonate fixation into glucose and other metabolites in the liver of the starved rat under halothane anaesthesia. Metabolic channelling of mitochondrial oxaloacetate. 392 30

Branched-chain amino acid metabolism in skeletal muscle promotes the production of alanine, an important precursor in hepatic gluconeogenesis. There is controversy concerning the origin of the carbon skeleton of alanine produced in muscle, specifically whether it is derived from carbohydrate via glycolysis (the glucose-alanine cycle) or from amino acid precursors (viz. glutamate, valine, isoleucine, methionine, aspartate, asparagine) via a pathway involving phosphoenolpyruvate (PEP) carboxykinase and pyruvate kinase, or NADP-malate dehydrogenase (malic enzyme). The relevant literature is reviewed and it is concluded that neogenic flux from amino acids is unlikely to be of major quantitative importance for provision of the carbon skeleton of alanine either in vitro or in vivo. Evidence is presented that branched-chain amino acid oxidation in muscle is incomplete and that the branched-chain 2-oxo acids and the products of their partial oxidation (including glutamine) are released. The role of these metabolites is discussed in the context of fuel homeostasis in starvation.
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PMID:Alanine and inter-organ relationships in branched-chain amino and 2-oxo acid metabolism. Review. 393 2

To evaluate whether the alterations in amino acid (AA) metabolism that follow the lambda-carrageenan injury are direct consequences of wounding and are therefore independent of food intake, plasma AA, in vivo muscle intracellular free AA, and AA release during isolated hindlimb perfusions were determined in pentobarbital-anesthetized rats with lambda-carrageenan-induced hindlimb muscle wounds (W) and in pair-fed (PFC) and ad libitum-fed (ALC) non-wounded controls. Both PFC and W animals showed different plasma and muscle intracellular AA composition that ALC. The alterations observed in these compartments in W animals may not have resulted exclusively as a consequence of the wound. Wounded hindlimbs released more AA during perfusion than either control group. The marked increase in net protein catabolism of W muscle appeared to be related to wounding and not a consequence of partial starvation. The normalized release (amino acid/phenylalanine ratio) of glutamine (W less than ALC), alanine (W less than PFC and ALC), and the branched-chain amino acids (W greater than PFC and ALC) differed among groups, suggesting an alteration in the metabolism of these AA in W tissue.
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PMID:Amino acid metabolism after lambda-carrageenan injury to rat skeletal muscle. 394 10

The transport of the aromatic amino acids into isolated rat liver cells was studied. There was a rapid and substantial binding of the aromatic amino acids, L-alanine and L-leucine to the plasma membrane. This has important consequences for the determination of rates of transport and intracellular concentrations of the amino acids. Inhibition studies with a variety of substrates of various transport systems gave results consistent with aromatic amino acid transport being catalysed by two systems: a 2-aminobicyclo(2,2,1)heptane-2-carboxylic acid (BCH)-insensitive aromatic D- and L-amino acid-specific system, and the L-type system (BCH-sensitive). The BCH-insensitive component of transport was Na+-independent and facilitated non-concentrative transport of the aromatic amino acids; it was unaffected by culture of liver cells for 24 h, by 48 h starvation, dexamethasone phosphate or glucagon. Kinetic properties of the BCH-inhibitable component were similar to those previously reported for the L2-system in liver cells. The BCH-insensitive component was a comparatively low-Km low-Vmax. transport system that we suggest is similar to the T-transport system previously seen only in human red blood cells. The results are discussed with reference to the importance of the T- and L-systems in the control of aromatic L-amino acid degradation in the liver.
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PMID:Transport of the aromatic amino acids into isolated rat liver cells. Properties of uptake by two distinct systems. 395 48

Determination of 14CO2 content in expired air after the intravenous injection of energetic substrates marked by the radioactive carbon to the pigs showed that the oxidative intensity of these substrates decreases in the series: [6-14C]glucose greater than [1-14C] alanine greater than [1-14C]leucine greater than [1-14C]glucose. The oxidation intensity of all substrates under study except for [1-14C]palmitate in the organism of one-day satisfied pigs is considerably higher, than during the first two hours after their birth. The starvation of pigs during the first 24 hours increases the oxidation of both investigated amino acid and [1-14C]-palmitate in tissues of their organism with a decrease in the metabolic intensity of [6-14C] and [1-14C]glucose.
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PMID:[Oxidation in vivo of glucose, palmitate, alanine and leucine in the pig during the neonatal period]. 400 73

When king penguin chicks are 3-4 mo old, they enter a season of interrupted growth due to long periods of fasting, because they are irregularly fed in winter. Nine captive chicks [mean initial body mass (m) = 12.5 kg] had fasted an average of 5 mo at the end of the experiment; m was then 4.0 kg, a 68% decrease. They probably could have fasted longer, since chicks of parents delayed in the return to the colony die from starvation at an m of 3.0 kg. The long fast could be divided into three periods based on the changes in rate of decrease of m. The remarkable resistance of king penguin chicks to starvation may be partly explained by their ability to maintain protein sparing for as much as 4 mo, the duration of period II; plasma concentrations of uric acid, urea, and alanine were then minimum, 0.1, 0.4, and 0.4 mmol X l-1 respectively. Particular changes during this period, i.e., progressive increase of beta-hydroxybutyrate and decrease of glucose concentrations, might contribute to the efficiency of protein sparing. Period III was marked by a rise in protein utilization, plasma concentrations of uric acid, urea, and alanine increasing to 0.7, 1.5, and 0.8 mmol X l-1, respectively.
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PMID:Five months of fasting in king penguin chicks: body mass loss and fuel metabolism. 405 Oct 24

In incubated colonocytes isolated from rat colons, the rates of utilization O2, glucose or glutamine were linear with respect to time for over 30 min, and the concentrations of adenine nucleotides plus the ATP/ADP or ATP/AMP concentration ratios remained approximately constant for 30 min. Glutamine, n-butyrate or ketone bodies were the only substrates that caused increases in O2 consumption by isolated incubated colonocytes. The maximum activity of hexokinase in colonic mucosa is similar to that of 6-phosphofructokinase. Starvation of the donor animal decreased the activities of hexokinase and 6-phosphofructokinase, whereas it increased those of glucose-6-phosphatase and fructose-bisphosphatase. Isolated incubated colonocytes utilized glucose at about 6.8 mumol/min per g dry wt., with lactate accounting for 83% of glucose removed. These rates were not affected by the addition of glutamine, acetoacetate or n-butyrate, and starvation of the donor animal. Isolated incubated colonocytes utilized glutamine at about 5.5 mumol/min per g dry wt., which is about 21% of the maximum activity of glutaminase. The major end-products of glutamine metabolism were glutamate, aspartate, alanine and ammonia. Starvation of the donor animal decreased the rate of glutamine utilization by colonocytes, which is accompanied by a decrease in glutamate formation and in the maximum activity of glutaminase. Isolated incubated colonocytes utilized acetoacetate at about 3.5 mumol/min per g dry wt. This rate was not markedly affected by addition of glucose or by starvation of the donor animal. When colonocytes were incubated with n-butyrate, both acetoacetate and 3-hydroxybutyrate were formed, with the latter accounting for only about 19% of total ketones produced.
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PMID:Fuel utilization in colonocytes of the rat. 407 34

Pyridoxineless mutants of Escherichia coli are lysed in a few hours when starved for pyridoxine in a glucose minimal medium containing glycine at 10 mM. The lysis is prevented equally well by l-alanine and by d-alanine when either is present at 0.1 mM. The lysis is potentiated by 0.5 mM l-methionine. The peculiar susceptibility of E. coli B to glycine-mediated lysis during starvation for pyridoxine suggests that the starvation reduces the availability of some normal antagonist of glycine, presumably alanine.
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PMID:Lysis of Escherichia coli by glycine is potentiated by pyridoxine starvation. 458 21

Pseudomonas aeruginosa was shown to utilize the majority of commonly occurring amino acids for growth as either the sole carbon or the sole nitrogen source. During carbon or nitrogen deprivation, the rates of transport of most of the amino acids remained unchanged; however, the transport rates for glutamate, alanine, and glycine increased under these conditions and the transport rates for leucine and valine decreased. Normal transport rates for these amino acids were resumed immediately upon the addition of the required nutrient. In the absence of an external source of carbon or of nitrogen, pool amino acids underwent rapid degradation. (14)C-Amino acid pulse experiments indicated that the constitutive amino acid catabolic enzymes, normally present in the organism during growth with glucose as the carbon source, were responsible for rapid pool losses. Nutrient starvation in the presence of chloramphenicol did not prevent amino acid catabolism. This enzymic activity is interpreted as providing P. aeruginosa with a selective advantage for survival during conditions of carbon or nitrogen starvation.
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PMID:Influence of carbon or nitrogen starvation on amino acid transport in Pseudomonas aeruginosa. 498 Oct 58


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