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)

Nitrogen starvation has been shown to increase the cytosolic arginine concentration and to accelerate protein turnover in mycelia of Neurospora crassa. The cytosolic arginine is derived from a metabolically inactive vacuolar pool. Redistribution of arginine between cytosolic and vacuolar compartments is the result of mobilization of this metabolite in response to nitrogen starvation. Mobilization of arginine (and purines) also occurred in response to glutamine limitation, but arginine accumulated upon proline starvation. These observations indicate that mobilization is a consequence of glutamine limitation rather than a general response to amino acid starvation (or limitation). Analysis of the amino acid pools in mycelia subjected to starvation or limitation suggests that glutamine (or a metabolite derived from glutamine) provides a signal which determines the metabolic fate of vacuolar arginine. The results are consistent with the hypothesis that vacuolar compartmentation provides a readily available store of nitrogen-rich compounds to be utilized during differentiation or under conditions of nutritional stress.
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PMID:Mobilization of vacuolar arginine in Neurospora crassa. Mechanism and role of glutamine. 623 20

The nucleotide sequence of the yeast gene TRP5 and its 5' and 3' flanking regions was determined. The deduced coding sequence for tryptophan synthase contains 2,127 base pairs. The protein chain has a calculated molecular weight of 76,544. Yeast tryptophan synthase, a bifunctional protein, has a primary structure which corresponds to an Escherichia coli tryptophan synthase alpha chain-beta chain fusion. An NH2-terminal 239 amino acid segment of yeast tryptophan synthase is homologous with E. coli tryptophan synthase alpha subunit, while a distal 389 amino acid residue segment is homologous to the E. coli tryptophan synthase beta chain. This order of segments of the yeast enzyme is the reverse of the chromosomal order characteristic of all prokaryotes that have been examined. The two segments are joined by a connecting region of 28 residues in the yeast enzyme which is not homologous to either the alpha or beta chains of the bacterial enzyme. A portion of the connecting region of yeast tryptophan synthase exhibits nucleotide sequence similarity to the 3' terminus of E. coli trpC and the trpC-trpB intercistronic region. Active site cysteine, histidine, and lysine residues in the beta 2 subunit of E. coli tryptophan synthase are conserved in the yeast enzyme. Also conserved in the yeast enzyme are 6/8 amino acid residues having an important role in maintaining the structure and function of the E. coli tryptophan synthase alpha subunit. S1 nuclease mapping was used to identify three major mRNA transcripts with different 5' termini. Potential T-A-T-A sites for transcription initiation were identified, as well as other sequences that occur frequently in yeast genes. A 5' flanking region of TRP5 was shown by DNA/DNA hybridization to be present in multiple copies in the yeast genome. TRP5 mRNA levels, measured by RNA/DNA hybridization, increased 2- to 7-fold in response to starvation for either tryptophan or histidine, indicating transcriptional regulation.
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PMID:Yeast gene TRP5: structure, function, regulation. 627 87

In a prospective controlled clinical trial, 70 patients with normal gastrointestinal function were randomised to receive either an elemental diet based on Vivonex HN or an isonitrogenous isocalorie polymeric diet based on Clinifeed 400, administered by continuous 24 hour nasogastric infusion. The two groups of patients were well matched for age, sex, diagnosis, prior starvation, duration of feeding, initial nutritional status, and metabolic status. Nitrogen losses were significantly less on the polymeric feed, despite similar intakes. Serum transferrin rose significantly (1.85 +/- 0.2 to 2.30 +/- 0.2 g/l, p less than 0.05) only in the Clinifeed group, but nutritional parameters were otherwise maintained in both groups. The incidence of diarrhoea (Vivonex, 23.5%; Clinifeed, 30.6%) was not significantly different and was attributable to antibiotics in most cases. Hypokalaemia, which occurred in nearly half the patients, was equally distributed in the two groups, but hypophosphataemia occurred more often in the Vivonex group (p less than 0.05). Liver enzyme disturbances were similar in both groups. The present findings, therefore, provide no evidence that chemically defined 'elemental' diets containing free amino acids as their nitrogen source are in any way superior to polymeric diets containing whole protein and fat when administered to patients with normal gastrointestinal function.
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PMID:Comparison of an elemental and polymeric enteral diet in patients with normal gastrointestinal function. 640 Dec 57

With both enteral and parenteral feedings, the amount of nutrients required depends on the degree of nutritional depletion, level of hypermetabolism, and the phase of the patient's response to illness or injury. Protein requirements are significantly increased in the critically ill. In skeletal trauma, energy needs are increased approximately 25%, in sepsis, 50%, and in severe burns, 75-100%. Energy requirements increase also but in part are met by body fat reserves. While D5W solutions were once thought to spare body proteins by reducing gluconeogenesis, it is now known that such semi-starvation regimes are deficient by omitting protein intake. Enteral and parenteral feeding techniques have developed as precise methods for administering a balance of required protein and calories. A comprehensive nutritional assessment will determine patient nutrient requirements. The marasmic patient without significant stress will generally require 30-40 kcal/kg and 1.5 g protein/kg of ideal body weight. Such support should lead to a slow weight gain and positive nitrogen balance of 2-6 g nitrogen. In the hypoalbunemic patient with concomitant stress, nitrogen retention will be limited until the stress, i.e. acute injury or infection, is relieved. Nitrogen (g):calorie (kcal) intake will average 1:80. During therapy, nutritional assessment parameters must be measured periodically to evaluate the effectiveness of the nutritional regime.
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PMID:Modern parenteral and enteral nutrition in critical care. 641 94

This study was undertaken to determine the changes in basic nutritional indices associated with major colonic surgery accompanied by periods of semi-starvation. Changes in weight, serum albumin, nitrogen balance, and maximum exercise capacity were studied. Weight loss was 5.5 +/- 1 per cent, serum albumin decreased 0.20 +/- 0.15 gm per cent. Nitrogen loss was 5.9 +/- 0.9 gm per day and maximum exercise capacity decreased by 13.5 +/- 1.8 per cent. Nitrogen balance improved when amino acids were substituted for glucose as the maintenance regimen, but no corresponding improvement in exercise performance could be demonstrated. It is concluded that major colonic surgery associated with moderate periods of semi-starvation is associated with an average nitrogen loss of 5.9 +/- 0.9 gm per day and a 13.5 +/- 1.8 per cent loss in maximum exercise capacity or effective muscle mass.
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PMID:An assessment of nutritional depletion following major colonic surgery. 648 74

We describe an NH4+-specific transport system in the N2-fixing symbiotic actinomycete Frankia sp. strain CpI1. [14C]methylammonium was used as an NH4+ analog. No specific transport process was detected when cells were grown on high concentrations of NH4+. A transport system with a high affinity for CH3NH3+ was synthesized after 3 to 4 h of nitrogen starvation. Methylammonium transport was not significantly inhibited by a variety of amino acids, primary amines, and polyamines. Ammonium completely eliminated CH3NH3+ transport. The Km for CH3NH3+ transport was around 2 +/- 1.8 microM with a Vmax of 4 to 5 nmol/min per mg of protein. The electron transport inhibitors cyanide and azide eliminated uptake, as did the uncoupler carbonyl cyanide-m-chlorophenylhydrazone. The sulfydryl reagent p-chloromercuribenzoic acid and the heavy metal thallium also inhibited uptake, suggesting the presence of an NH4+-specific permease. Concentration of CH3NH3+ across the membrane was demonstrated by conducting uptakes at low temperature to slow the metabolism of CH3NH3+ by glutamine synthetase. At 7 degrees C most of the label was concentrated inside the cells in a form that could be chased from the cells by adding excess NH4+ to the medium. At 30 degrees C most of the label was present as an impermeant metabolite. Thin-layer chromatography of cell extracts confirmed that the radioactivity inside the cells was mainly in the form of CH3NH3+ at 7 degrees C but was present as an unidentified metabolite at 30 degrees C. These studies demonstrate that Frankia sp. strain CpI1 has a high-affinity NH4+ transport system that is synthesized in response to NH4+ starvation.
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PMID:[14C]methylammonium transport by Frankia sp. strain CpI1. 650 Dec 18

The main regulatory mechanisms controlling the synthesis of neural protease in batch cultures of a strain of Aspergillus were studied. Protease was inducible in this strain. No activity appeared during the trophophase when the organism was grown in a minimal medium, unless an inducer was added. Gelatine had the best induction effect among all the tested substances. The growth kinetics and enzyme production in a culture medium containing gelatine as the sole carbon and nitrogen source was determined. In spite of these results, protease activity was clearly detectable during the idiophase in absence of an external inducer. Furthermore, the addition of gelatine to cultures during the idiophase resulted in a decrease of the enzyme activity. This behaviour could be due to internal autoinduction generated by accelerated protein turnover of the nitrogen starved cells. The addition of gelatine probably reduced the protein starvation. Protease synthesis was sensitive to repression by rapidly assimilable carbon sources such as glucose and glycerol. Ammonia also caused an important repression, while nitrate and amino nitrogen had no effect. It was concluded that the synthesis of this enzyme is controlled by induction, catabolite repression, and ammonia repression, and that the enzyme production period could be adjusted by adequate formulation of the culture medium.
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PMID:[Effect of the medium composition on the synthesis of protease by Aspergillus sp]. 675 51

The effect of a number of conditions on the amount of cyanophycin granule polypeptide [multi-L-arginyl poly(L-aspartic acid)] formed in the unicellular cyanobacterium Aphanocapsa 6308 was determined. Light, CO2, sulfur, and phosphorus starvation as well as the addition of arginine to culture media increased the amount of cyanophycin granule polypeptide in cells when compared with that in cells grown under conditions optimal for growth. Nitrogen limitation and reduction of growth temperature to 30 degrees C decreased the amount of cyanophycin granule polypeptide on a dry-weight basis. Shift-up and shift-down experiments suggest cyanophycin granule polypeptide may be a reserve nitrogen polymer in Aphanocapsa 6308.
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PMID:Cyanophycin granule polypeptide formation and degradation in the cyanobacterium Aphanocapsa 6308. 676 88

Folic acid is a chemoattractant for the slime mold Dictyostelium minutum V3. The activity of extracellular folic acid is regulated by a folic acid C9-N10 splitting enzyme (FAS). The products were identified as pterin-6-aldehyde and p-amino-benzoylglutamic acid. The enzyme was stabilized by EDTA. For the extracellular enzyme, the Km was 10(-7) M, and the optimal pH was 4.0. During starvation, FAS activity was mainly secreted into the medium; after 3 h, a plateau was reached. The membrane-bound activity was constant, but only 12% of the extracellular activity at 3 h. Intracellular activity also increased up to 3 h to a level of 23% of the extracellular FAS. The substrate recognition of FAS was found to be based on 4-O or N3 or both, N5 or N8 or both, N10, and the p-aminobenzoic acid moiety, whereas 2-NH2, N1, and the glutamic acid moiety were not recognized. Other slime mold species were found to secrete FAS with 20-fold or more reduced activity than D. minutum V3.
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PMID:Characterization of the folic acid C9-N10-cleaving enzyme of Dictyostelium minutum V3. 684 18

The present work gives evidence that, in contrast to the situation reported by Pontremoli et al. for the rabbit (Proc, Natl. Acad. Sci. U.S.A. 76, 6323-6325, 1979; Arch. Biochem. Biophys. 203, 390-394, 1980; Proc. Natl. Acad. Sci. U.S.A, 79, 5194-5196, 1982), starvation for as long as 3 days does not cause intracellular covalent modification and inactivation of fructose-P2 aldolase molecules in rat liver cells. This conclusion is based on our observations that liver aldolase molecules isolated from fed and starved rats in the presence of proteolytic inhibitors were not distinguished on the basis of specific catalytic activity, electrophoretic mobility, subunit molecular weight, NH2-terminal structure, or COOH-terminal structure. Further, the approximate 40% loss in rat liver mass which occurred during the 3-day fast was not associated with appreciable changes in the content of aldolase and most other abundant cytosolic proteins per gram of rat liver, as judged by electrophoretic analysis of 100 000-g soluble fractions of liver extracts. Finally, a 3-day fast had no appreciable effect on the relative rates of synthesis of aldolase and most other abundant cytosolic proteins in rat liver. Our findings suggest that nutrient deprivation has no preferential effect on the concentration or metabolism of aldolase in rat liver cells.
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PMID:Similarities in properties, content, and relative rates of synthesis of fructose-P2 aldolase in livers of fed and starved rats. 687 82


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