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

Caulobacter crescentus accumulated guanosine tetraphosphate in response to nitrogen starvation but not in response to amino acid starvation. Nitrogen starvation also acted specifically to inhibit certain transitions in the C. crescentus life cycle, and guanosine tetraphosphate may act as an intracellular regulator of cell cycle events.
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PMID:Conditions that trigger guanosine tetraphosphate accumulation in Caulobacter crescentus. 720 47

In this study we examine the effect of different hypocaloric nutritional regimens on nitrogen balance in patients following total hip replacement and compare it to that of normal subjects on strict bed rest. The interrelationship between nitrogen balance, energy expenditure, and urinary free norepinephrine excretion is analyzed with emphasis on the effects of nutrition on these relationships. Amino acid infusions following major elective orthopedic surgery had no nitrogen-sparing effect above that of 5% dextrose. Optimum nitrogen balance was obtained by administration of both 5% dextose and 3.5% amino acids. Patients receiving 5% dextrose showed no increase in resting energy expenditure in postoperative period compared to the preoperative control value. However, patients receiving amino acid infusions showed a 14% rise in energy expenditure postoperatively. Failure to administer 5% dextrose was associated with a high urinary norepinephrine excretion postoperatively. In normal subjects on bed rest either 5% dextrose or total starvation resulted in a marked fall in resting energy expenditure, whereas amino acid infusions isocaloric to the carbohydrate intake prevented any fall in resting energy expenditure. Nitrogen balance was improved with amino acid infusions in normal subjects. This study suggests the effect of amino acid infusions is highly dependent on the metabolic state of the patient.
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PMID:Energy expenditure, nitrogen balance, and norepinephrine excretion after injury. 720 95

Three experiments were made with adult White Leghorn cockerels to measure the effect of indigestible organic matter on the metabolic fecal and endogenous urinary energy and nitrogen losses. When a cellulose:carboxymethyl cellulose mixture was placed in the crops of fasted birds the energy excreted during the subsequent 24 and 48 hr was greater than, but proportional to, the energy input. The linear regression coefficients were not different (P greater than .05) from unity, indicating that the metabolic and endogenous energy output neither increased nor decreased when cellulose was administered. This finding was confirmed when graded levels of sawdust were fed in place of cellulose. It is concluded that the use of a fasted bird to measure the metabolic and endogenous energy loss, as in the bioassay for true metabolizable energy, is valid and the changes induced by the nature or quantity of dietary fiber are insignificant. Nitrogen excretion was not affected by the feeding of cellulose or sawdust. Excretion increased with the duration of starvation but the difference diminished as the bird aged and became heavier. Nitrogen losses varied greatly among birds but tended to be characteristic of a bird within an experiment.
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PMID:Metabolic plus endogenous energy and nitrogen losses of adult cockerels: the correction used in the bioassay for true metabolizable energy. 730 42

During batch cultivation of Propionibacterium shermanii in a medium with glucose, ATP content in the cells (nmoles per 1 mg of dry biomass) increased up to the middle of the log phase, and decreased abruptly by the end of the log phase. When the culture was grown in a medium with lactate, the maximal level of ATP (3 nmoles/mg) was lower than in a medium with glucose (5 nmoles/mg). Nitrogen starvation of the culture was accompanied with a decrease in the level of ATP. If ammonium sulphate was added to such a culture, first the level of ATP increased and then the growth began. Addition of ammonium sulphate, after 72 h, to the nitrogen--deficient culture, the original density of whose cell suspension was over 0.25 mg/ml, did not induce the growth, although the level of ATP also increased.
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PMID:[ATP pool in Propionibacterium shermanii cells under various culture conditions]. 732 58

Selenomonas ruminantium accumulated large quantities of intracellular polysaccharide when grown in simple defined medium in a chemostat, particularly at low dilution rate under NH3 limitation when the carbohydrate content of the cells was greater than 40% of the dry weight. This polysaccharide was used as a source of energy under conditions of energy starvation. Abundant, densely staining cytoplasmic granules were observed by electron microscopy in sections stained by the periodic acid-thiocarbohydrazide-osmium technique. The polysaccharide was extracted in 30% KOH followed by precipitation with 60% ethanol and was found to be a glucose homopolymer. Sepharose 4B gel filtration and iodine-complex spectroscopy showed that the polysaccharide was of the glycogen type with a molecular weight of 5 X 10(5) to greater than 20 X 10(5) and an average chain length of 12 glucose residues.
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PMID:Cytoplasmic reserve polysaccharide of Selenomonas ruminantium. 738 59

Nitrogen regulation of transcription in Escherichia coli requires sensation of the intracellular nitrogen status and control of the dephosphorylation of the transcriptional activator NRI-P. This dephosphorylation is catalyzed by the bifunctional kinase/phosphatase NRII in the presence of the dissociable PII protein. The ability of PII to stimulate the phosphatase activity of NRII is regulated by a signal transducing uridylyltransferase/uridylyl-removing enzyme (UTase/UR), which converts PII to PII-UMP under conditions of nitrogen starvation; this modification prevents PII from stimulating the dephosphorylation of NRI approximately P. We used purified components to examine the binding of small molecules to PII, the effect of small molecules on the stimulation of the NRII phosphatase activity by PII, the retention of PII on immobilized NRII, and the regulation of the uridylylation of PII by the UTase/UR enzyme. Our results indicate that PII is activated upon binding ATP and either 2-ketoglutarate or glutamate, and that the liganded form of PII binds much better to immobilized NRII. We also demonstrate that the concentration of glutamine required to inhibit the uridylyltransferase activity is independent of the concentration of 2-ketoglutarate present. We hypothesize that nitrogen sensation in E. coli involves the separate measurement of glutamine by the UTase/UR protein and 2-ketoglutarate by the PII protein.
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PMID:The Escherichia coli PII signal transduction protein is activated upon binding 2-ketoglutarate and ATP. 762 80

Cell differentiation in Dictyostelium results in the formation of two cell types, stalk and spore cells. The stalk cells undergo programmed cell death, whereas spore cells retain viability. The current evidence suggests that stalk cell differentiation is induced by Differentiation Inducing Factor (DIF), while spore cell differentiation occurs in response to cAMP. We have discovered the first developmentally regulated Dictyostelium gene, the glycogen phosphorylase gene 2 (gp2) gene, that can be induced by both DIF-1 and cAMP, suggesting the possibility of a new group of developmentally regulated genes that have DIF-1 and cAMP dual responsiveness. The gp2 gene was found to be expressed in both prestalk/stalk cells and prespore/spore cells. The DIF-1 competence of the gp2 gene required uninterrupted development, whereas the cAMP-competence for the gene required only starvation. Both DIF-1 and cAMP induction of the gene could be inhibited by NH3, a factor that is thought to act as a developmental signal in Dictyostelium. Another developmental signal, adenosine, was found to repress the DIF-1 induction of the gp2 gene. Two introns in the gp2 gene were examined for their involvement in the regulation of the gene, but no regulatory function was detected. A model for the regulation of the gp2 gene during the development is proposed.
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PMID:Dual regulation of the glycogen phosphorylase 2 gene Dictyostelium discoideum: the effects of DIF-1, cAMP, NH3 and adenosine. 802 27

Nitrogen starvation of Schizosaccharomyces pombe induces a differentiated state in which haploid cells mate and sporulate. esc1+, a newly isolated S.pombe cDNA that promotes this sexual differentiation, encodes a putative transcription factor with a helix-loop-helix (HLH) motif similar to those of the human MyoD and Myf-5 myogenic differentiation inducers. Disruption of esc1+ in wild-type cells leads to a decrease in the efficiency of sexual conjugation, an early step in sexual differentiation. The disruption was also able partially to substitute for cAMP, an inhibitor of differentiation, to suppress the lethal, constitutive differentiation induced by the pat1 mutation. Conversely, overexpression of this cDNA conferred partial resistance to cAMP-mediated inhibition of differentiation. Transcription from this novel gene was induced early in response to nitrogen starvation and is largely independent of the ste11+ gene product, which is required for the differentiation-specific expression of other genes. Thus, this MyoD/Myf-5-like protein appears to promote sexual differentiation by modulating responses to decreases in cAMP, a part of the nitrogen starvation signal that induces differentiation.
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PMID:A Schizosaccharomyces pombe gene that promotes sexual differentiation encodes a helix-loop-helix protein with homology to MyoD. 838 48

gamma-Linolenic acid (GLA) production using a high GLA producing marine green alga, Chlorella sp. NKG 042401, was studied. GLA was presented in the galactolipid fraction (37.9%/total fatty acids). The effects of growth conditions on GLA production were studied. Optimum salinity for GLA production was 5 g l-1, at which salinity the highest cell concentration was achieved, resulting in a 1.6-fold increase in GLA productivity. Total fatty acid, however, was not drastically affected by change of salinity. Nitrogen starvation decreased the ratio of unsaturated fatty acids, and consequently GLA ratio in total fatty acid decreased. The urea adduct method was used to concentrate GLA from crude extract. As a result, after 5 sequential concentration procedures, GLA was concentrated 5-fold with a yield of 49%.
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PMID:Production of gamma-linolenic acid from the marine green alga Chlorella sp. NKG 042401. 838 22

This study has evaluated the effects of recombinant human insulin-like growth factor I (rhIGF-I) to moderately stressed post-operative patients provided with dextrose as the only exogeneous substrate. Thirty patients who underwent elective colorectal surgery were randomized to receive either rhIGF-I (80 micrograms kg-1 bw) subcutaneously twice daily or placebo injections in a double-blind parallel group design. Nitrogen balance, urinary 3-methyl-histidine excretion plasma growth hormone (GH), serum cortisol, IGF-I binding proteins (IGFBP-1,3), glomerular filtration rate, plasma amino acid concentrations and whole-body energy expenditures were measured as effector variables during days 1-5 post-operatively. Animal and isolated tissue experiments were performed as additional control experiments to confirm cellular effectiveness of the recombinant material. rhIGF-I increased significantly the glomerular filtration rate and prevented the adaptive decrease in whole-body energy expenditure in response to partial starvation in the postoperative period. Serum and plasma concentrations of IGFBP-1,3 cortisol, blood glucose and amino acids were not significantly influenced by rhIGF-I administration, while plasma GH levels decreased significantly as expected. rhIGF-I had no effect on either nitrogen balance or protein breakdown (3-methylhistidine excretion) in post-operative patients on dextrose supplementation only, although plasma concentrations of IGF-I increased from 130-140 ng mL-1 to a range of 300-450 ng mL-1. In contrast, IGF-I stimulated the synthesis of both globular and myofibrillar proteins (+50%, P < 0.01), when given as a single dose (100 micrograms kg-1) 2 h before measurements of protein synthesis in skeletal muscles of overnight fasted adult mice. This stimulatory effect by IGF-I (1 microgram mL-1) was also confirmed by measurements of skeletal muscle protein synthesis in vitro (+40%, P < 0.05). Orally re-fed mice had a normal transcription of IGF-I mRNA in skeletal muscle cells, while overnight fasted mice showed a trend to down-regulated transcription. Our results demonstrate that rhIGF-I has several significant physiological effects, without major side-effects, when supplied to partially starved patients in the post-operative phase. The lack of a whole-body nitrogen sparing effect by rhIGF-I alone to post-operative patients is not clear, but was most likely explained by subnormal plasma concentrations of amino acids.
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PMID:The effect of recombinant human IGF-I on protein metabolism in post-operative patients without nutrition compared to effects in experimental animals. 855 66


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