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)

Plasma concentrations of the branched-chain amino acids (leucine, isoleucine, and valine) are more prominently affected than the concentrations of other amino acids by changes in dietary-caloric, protein, fat, and carbohydrate-intake in man. For example, within a day of starvation or protein deprivation, there are increases or decreases, respectively, in concentrations of these amino acids in the plasma of healthy human volunteers. The cellular mechanisms of these changes have been investigated in rats, since the changes in the plasma branched-chain amino acid concentrations in response to the previously stated dietary alterations are similar to those found in man. Among the tissues studied (liver, skeletal muscle, heart, kidney, and intestine) only liver and the skeletal muscle exhibit changes in branched-chain amino acid concentrations in response to dietary alteation. Changes in plasma concentrations appear to reflect more intimately those of the muscle than theliver. After 8 days of starvation, there is a 25% decrease in the muscle protein, but after 8 days of protein deprivation, there is no significant change in the muscle mass. Increases in concentrations of branched-chain amino acids in the muscle are much smaller than the amounts of these amino acids lost as protein constituents form the muscle during fasting. Changes in tissue transport, transamination, oxidation, or metabolic conversions of branched-chain amino acids in tissues. It is concluded that increased muscle protein breakdown, which provides substrates for enhanced gluconeogenesis in the liver and enhanced branched-chain amino acid oxidation in the muscle, is the major mechanism of hyperbranched-chain aminoacdemia in starvation. On the other hand, the principal factors in the development of hypobranched-chain aminoacidemia during protein deprivation are absence of exogenous amino acids as well as curtailed muscle protein breakdown.
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PMID:Metabolism of branched-chain amino acids in altered nutrition. 79 82

The heterogeneity of undermodified phenylalanine tRNA produced in relaxed control E. coli during amino acid starvation was investigated. Examination of the RPC-5 elution profiles of tRNAPhe prepared from non-starved cells and cells starved of a variety of amino acids, including some known to be involved in the formation of modified bases revealed that: (1) only one species of fully modified tRNAPhe appears to occur in cells grown in enriched medium; (2) at least two chromatographically unique isoacceptor species are observed in addition to the normal tRNAPhe in starved cells; (3) the unique, undermodified species of tRNAPhe from leucine-starved cells, known to be deficient in dihydrouridine, pseudouridine, 2-thiomethyl-N6-(delta2-isopentenyl) adenosine and 3-(3-amino-3-carboxypropyl) uridine, co-elute with the unique species produced in cells starved of histidine or arginine or treated with puromycin or chloramphenicol; (4) additional unique species of tRNAPhe can be detected in methyl- and sulfur-deficient tRNA from methionine- and cysteine-starved cells; (5) analysis of phenoxyacetylated tRNA revealed that the chromatographically unique and normal species from starved cells contain subspecies deficient in 3-(3-amino-3-carboxypropyl) uridine; and (6) using phenoxyacetylation as a means of effecting the resolution of undermodified subspecies, a total of at least ten chromatographically unique subspecies of rRNAPhe were detected in an organism that appears to posses only one gene for tRNAPhe. Taken together, the results support the view that there are both general and specific effects of amino acid starvation on the post-transcriptional modification of tRNA.
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PMID:General and specific effects of amino acid starvation on the formation of undermodified Escherichia coli phenylalanine tRNA. 79 74

Considerable decrease of polysome number (22% as compared with 48% in normally grown culture) was observed under methionine starvation of E. coli Hfr (Met-)culture . At the same time the amount of 70S ribosomes increased up to 32%, while it was 2--6% in the control, the content of free ribosome subunits (50S+30S) being stable. The number of polysomes was the same (congruent to 50%) both in the control culture and under inhibition of protein synthesis in E. coli Hfr(Met-) cells with chloramphenicol, the content of 70S ribosomes was increased (30%) like in the case of methionine starvation, and the amount of free ribosome subunits was decreased (24% as compared with 46% in the control). The rate of ribosome movement in polysomes in the presence of chloramphenicol is comparable with that in the control. The rate of ribosome movement along mRNA under methionine starvation in 1.6 times lower than in normally grown E.coli culture. The level of (14)C-leucine incorporation into newly synthesizing polysome proteins under chloramphenicol inhibition of protein synthesis and methionine starvation comprised 20% and 12% of the incorporation level inthe control respectively. It suggested that ribosomes under inhibition of protein synthesis by chloramphenicol or amino acid starvation continue their movement along mRNA with the rate comparable with that in the control. However in this case no peptide bonds are formed ("abortive" translocation).
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PMID:[Rate of ribosome movement along messenger RNA in E. coli under normal and inhibited translation]. 79 17

Recent experience with three children who had non-ketotic hyperglycinemia suggested that interpretation of blood glycine levels in children is complex. The elevations of blood glycine in these children were quite modest, and comparable to those of other children admitted to hospital with other diseases. Often we find elevations of blood glycine in children who have had some degree of starvation before blood was taken for amino acid analysis. In a "typical" patient, valine, leucine, isoleucine and occasionally threonine are depressed, while the glycine level is raised. As nutrition improves all of the amino acids return to normal. Our data suggest that blood glycine levels in children with an acute episode of a debilitating disease need to be interpreted with respect to the immediate state of nutrition of the children.
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PMID:Interpretation of elevated blood glycine levels in children. 80 17

The recovery of Streptococcus mutans FA-1 in a complete, chemically defined medium was examined after 1, 3, and 6 h of essential amino acid deprivation. Amino acids could be divided into two groups based on their effect on the relative rates of recovery: those amino acids (leucine and cystine) that are precursors of protein only, and amino acids (glutamate/glutamine or lysine) that are incorporated into both protein and cell wall peptidoglycan. Culture turbidity, deoxyribonucleic acid, ribonucleic acid, protein and cell wall peptidoglycan measurements indicated rapid recovery after leucine/cystine starvation periods. However, a 6-h leucine/cystine deprivation resulted in a slower exponential rate of growth (180-min doubling time compared to the normal doubling time of 85 to 90 min) after recovery. Glutamate/glutamine starvation, on the contrary, resulted in greatly extended recovery periods, especially after 3- and 6-h amino acid deprivations. Macromolecular synthesis was most severely affected by 6-h glutamate/glutamine starvation and required 6 to 10 h for recovery of an exponential rate. A delay in the recovery of deoxyribonucleic acid and cell wall peptidoglycan synthesis beyond that of the other macromolecules was observed after 1 and 3 h of deprivation with either leucine/cystine or glutamate/glutamine. However, after a 6-h amino acid deprivation, deoxyribonucleic acid synthesis recovered more rapidly than that of the other macromolecules studied. The results are discussed in terms of the nutritional environment of the oral cavity and its effect on the growth and survival of S. mutans.
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PMID:Recovery of Streptococcus mutans after amino acid deprivation. 90 77

We determined the effects of feeding, starvation, and glucose infusion after starvation in newborn guinea pigs. We determined the rate of 14C-leucine incorporation into skeletal muscle (KS) as a measure of muscle protein synthesis and the rate of excretion of 3-methylhistidine as a measure of muscle myofibrillar protein catabolism (Kc). Fed newborns, who were in positive nitrogen balance, had the highest Ks and lowest Kc, while starved newborns had the lowest Ks and highest Kc. Infusing glucose after starvation decreased net protein catabolism and Kc, but did not increase Ks. The magnitude of change of Kc in response to starvation and glucose infusion was much greater than Ks. Changes in catabolic rate may influence net muscle protein balance to a greater degree than changes in synthetic rate.
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PMID:The effects of starvation, glucose infusion, and normal feeding, on muscle protein synthesis and catabolism in the newborn guinea pig. 95 2

L-Leucine-pyruvate transaminase (mol. wt. 70 000) in Gluconobactersuboxydans synthesized during nitrogen starvation contained a labile form which changed to the stable one later. The labile enzyme (mol. wt. 70 000) dissocated to the two proteinaceous components: a cationic one (mol. wt. 10 000--20 000) and an anionic one (mol. wt. 50 000--60 000), during column chromatography on DEAE-cellulose. The enzyme activity was reconstructed when they were mixed. The reconstructed enzyme had almost the same molecular size and enzymatic properties as the labile and the native stable enzymes.
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PMID:Resolution and complementation of the labile L-leucine-pyruvate transaminase. An intermediate during enzyme formation under nitrogen starvation in Gluconobacter suboxydans. 100 28

Examination of the transfer ribonucleic acid (tRNA) produced by starving, relaxed-control (rel minus) strains of Escherichia coli for required amino acids revealed the occurrence of a number of chromatographically unique subspecies. Leucine starvation results in the formation of new isoacceptor species of leucine-, histidine-, arginine-, valine-, and phenylalanine-specific tRNA and quantitative changes in the column profiles of serine, glycine, and isoleucine tRNA. Evidence that the unique tRNA species are synthesized de novo during amino acid starvation comes from the findings that the major unique leucine isoacceptor species is not formed in stringent control cells or in rel minus cells starved for uracil or treated with rifampin. Furthermore, heat treatment of the unique leucine tRNA does not alter its chromatographic behavior, indicating that the species is not an aggregate or nuclease-damaged form of a normal isoacceptor tRNA. The methyl acceptor activities of tRNA from leucine-starved and nonstarved rel+ or rel minus cells were found to be essentially the same. This result and the finding that the chromatographic behavior of the unique leucine-specific tRNA was not altered after treatment with tRNA methylase suggests that gross methyl deficiency is probably not the biochemical basis for the occurrence of the unique species.
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PMID:Formation of chromatographically unique species of transfer ribonucleic acid during amino acid starvation of relaxed-control Escherichia coli. 109 55

Regulation of T4-specific mRNA synthesis was studied during leucine starvation of a leucine-requiring stringent Escherichia coli B strain. This was done by imposing starvation prior to T4 infection and then letting RNA synthesis proceed for different time periods. Rifampin or streptolydigin was added to stop further RNA synthesis, and protein synthesis was restored by addition of leucine. Samples were withdrawn at different times, and the enzyme-forming capacities found that, during conditions which elicit the stringent response in uninfected bacteria, immediate early mRNA is not stringently regulated. This conclusion contradicts the earlier conclusion of others, obtained by measuring incorporation of radioactive uracil; this is explained by the observation of Edlin and Neuhard (1967), confirmed and extended by us to the T4-infected cell, that the incorporation of uracil into RNA of a stringent strain is virtually blocked by amino acid starvation, whereas that of adenine continues at 30 to 50% of the rate seen in the presence of the required amino acid.
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PMID:Regulation of early mRNA synthesis after bacteriophage T4 infection of Escherichia coli. 109 29

The unique leucine-, arginine-, valine-, and phenylalanine-specific transfer ribonucleic acids (tRNA's) produced in relaxed-control (rel-) Escherichia coli during leucine or arginine starvation are chromatographically similar to those produced by chloramphenicol treatment. The major unique rel- leucine-specific and phenylalanine-specific tRNA's are heterogeneous, accumulate with time of starvation, and can account for up to 70% of the respective amino acid acceptor activities. The changes which occur in the isoacceptor profiles for tRNALeu and tRNAPhe as a function of starvation time suggest that the unique species are undermodified precursors to the major isoacceptor species observed in nonstarved cells. Analyses of the isoacceptor patterns of tRNA from cells recovering from starvation suggest that the unique species of tRNALeu and tRNAPhe may not be normally occurring precursors. When leucine-starved cells were incubated in fresh, fully supplemented medium, the major unique tRNALeu and tRNAPhe appeared to be converted to normal species only slowly or not at all. The results are consistent with the view that some of the events in the post-transcriptional modification of tRNA may occur in an ordered sequence. An examination of the subcellular distribution of the unique leucine and phenylalanine tRNA's revealed that these species occur on the ribosome at about the same frequency as the major, normally occurring isoacceptor species. This result provides additional evidence of a precursor-product relationship for the unique and normal tRNA's and further indicates that there is no discrimination against the unique species by the ribosome.
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PMID:Unbalanced growth and the production of unique transfer ribonucleic acids in relaxed-control Escherichia coli. 110 85


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