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 influence of glucocorticoids on muscle glutamine production in starvation was studied by using cortisol-treated or non-cortisol-treated, starved, adrenalectomized rats. Administration of cortisol at physiological doses in vivo (1 mg/100 g body weight) to fasted, adrenalectomized rats increased the muscle ratio of glutamine/glutamate and the activity of glutamine synthetase after only 6 hours. Prior treatment of fasted, adrenalectomized animals with actinomycin D or proflavine abolished these increases by cortisol. Therefore, cortisol induces muscle glutamine synthetase, and this induction can be detected by changes in the fresh-muscle ratio of glutamine/glutamate. Using this ratio as a qualitative indicator of muscle glutamine synthesis, the role of glucocorticoids in modifying muscle glutamine production in starvation was studied. In fresh-frozen soleus, extensor digitorum longus, and diaphragm muscle, starvation led to greater ratios of glutamine/glutamate and higher levels of tyrosine, which are indicative of enhanced muscle protein turnover. These effects were not apparent in starved, adrenalectomized animals but were restored, at least partially, by administering a physiological dose of cortisol. Therefore, glucocorticoids seem essential for promoting muscle glutamine production in starvation probably by inducing the activity of glutamine synthetase.
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PMID:Role of glucocorticoids in increased muscle glutamine production in starvation. 290 Apr 64

The effects of different culture conditions on nitrate reductase activity and nitrate reductase protein from Monoraphidium braunii have been studied, using two different immunological techniques, rocket immunoelectrophoresis and an enzyme-linked immunosorbent assay, to determine nitrate reductase protein. The nitrogen sources ammonium and glutamine repressed nitrate reductase synthesis, while nitrite, alanine, and glutamate acted as derepressors. There was a four- to eightfold increase of nitrate reductase activity and a twofold increase of nitrate reductase protein under conditions of nitrogen starvation versus growth on nitrate. Nitrate reductase synthesis was repressed in darkness. However, when Monoraphidium was grown under heterotrophic conditions with glucose as the carbon and energy source, the synthesis of nitrate reductase was maintained. With ammonium or darkness, changes in nitrate reductase activity correlated fairly well with changes in nitrate reductase protein, indicating that in both cases loss of activity was due to repression and not to inactivation of the enzyme. Experiments using methionine sulfoximine, to inhibit ammonium assimilation, showed that ammonium per se and not a product of its metabolism was the corepressor of the enzyme. The appearance of nitrate reductase activity after transferring the cells to induction media was prevented by cycloheximide and by 6-methylpurine, although in this latter case the effect was observed only in cells preincubated with the inhibitor for 1 h before the induction period.
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PMID:Immunological approach to the regulation of nitrate reductase in Monoraphidium braunii. 291 54

Phosphoenolpyruvate carboxykinase (PEPCK) activity is present along the length of rat small intestine and in enterocytes throughout the villus-crypt axis. There is no detectable activity in submucosal layers. Messenger RNA encoding PEPCK is detectable in rat intestinal mucosa and the relative abundance increases markedly (3- to 8-fold) during starvation or streptozotocin-diabetes. However, these changes are not matched by changes in enzyme activity which are only slightly increased (1.5-fold). The intestine of neonatal rats possesses relatively high amounts of both PEPCK activity and mRNA. Based on the distribution and regulation of intestinal PEPCK, it is proposed that the enzyme does not play a significant role in either gluconeogenesis or glutamine catabolism in adult rats.
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PMID:Phosphoenolpyruvate carboxykinase of rat small intestine: distribution and regulation of activity and mRNA levels. 291

The liver is the "glucostat" of the organism and serves at the same time as an "ammonia-sink and pH stat". The key enzymes involved in glucose uptake and release and in urea and glutamine formation are reciprocally distributed over the liver parenchyma: The glucogenic enzymes phosphoenolpyruvate carboxykinase (PEPCK), fructosebisphosphatase (FBPase) and glucose-6-phosphatase (G6Pase) as well as the ureagenic enzyme carbamoylphosphate synthetase (CAPS) are predominant in the periportal zone. The glycolytic enzymes glucokinase (GK) and pyruvate kinase type L (PKL) as well as the glutaminogenic enzyme glutamine synthetase (GluNS) are prevalent in the perivenous zone. This heterogeneity appears to be a prerequisite for the normal "glucostat, ammonia-sink and pH-stat" function of the liver. After birth the liver is a gluconeogenic organ, only with weaning it becomes a "glycolytic/gluconeogenic" glucostat. In the rat zonation of PEPCK, G6Pase and CAPS developed gradually after birth and was completed before weaning, i.e. before it would be functionally required. After 2/3 partial hepatectomy the liver looses its normal glucostat function and becomes a gluconeogenic organ. With this change the zonation of PEPCK and PKL were also lost; it was restored only during the second week after operation. During starvation the liver also looses its glucostat function to become the major glucose supplier of the organism. Zonation of PEPCK and PKL were diminished to such an extent that the major function of the perivenous zone was altered from glucose uptake to release. In diabetes the liver does not loose its glucostat function; however, the function is severely impaired. Zonation of PEPCK was increased and that of PKL decreased in such a manner that the major function of the perivenous zone, glucose uptake, was not entirely changed but only diminished. It can be concluded that in the various physiological states studied the zonation of enzymes correlated well with the glucostat function of the liver.
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PMID:Dynamics of zonal hepatocyte heterogeneity. Perinatal development and adaptive alterations during regeneration after partial hepatectomy, starvation and diabetes. 301 Mar 76

The intestinal tract plays a central role in the protein catabolic response after injury and infection. The mucosa utilizes glutamine and thus spares glucose--presumably sparing this essential fuel source for tissues with an obligate glucose requirement. With inadequate nutritional support or prolonged stress, glutamine levels decrease in both the plasma and the tissue pools, which suggests that glutamine deficiency occurs. This is associated in time with atrophy of the gastrointestinal mucosa. This provision of dietary glutamine results in correction of the abnormally low glutamine concentrations and increased cellularity of the gut mucosa. The derangements in the intestinal mucosa associated with starvation, injury, infection, immunosuppression, chemotherapy, lack of enteral feedings, and other stresses are associated with a breakdown in the barrier function of the gut. Both bacteria and their toxins may enter the host from the intestinal lumen. Through interaction with the reticuloendothelial system, cytokines are produced, which stimulate the pituitary-adrenal axis and thus contribute to the stress response. The elaboration of glucocorticoids facilitates proteolysis, thus increasing glutamine release from skeletal muscle for gut repair. Although this homeostatic mechanism appears to aid mucosal repair and support immunologic responses, severe injury or prolonged glutamine deficits do not adequately support intestinal recovery and allow this cycle to become self-perpetuating (Fig 3). Adequate enteral feedings initiated early in the course of a disease appear to maintain adequate gut barrier function. In the frequent circumstance when feeding by this route is inadequate or impossible, glutamine-containing parenteral feedings offer an appropriate alternative therapy for bowel and immunologic support. Glutamine-containing parenteral feedings are associated with increased mucosal cellularity and improved survival after gut injury. Specific hormones also stimulate mucosal growth, and it is anticipated that a combination of hormones and specific nutrients will provide optimal support of the gut mucosa in the severely ill patient.
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PMID:The gut: a central organ after surgical stress. 305 97

This study set out to investigate the effect of three different parenterally administered diets on the free amino acid (AA) levels in the plasma, muscle, and liver of scalded rats. Diet I consisted of AA (1.4 g/100 g weight) and a high glucose dose (6 g/100 g weight), diet II consisted of AA and a low glucose dose (1.4 g/100 g weight) and in diet III only a low glucose dose was infused. Parenteral nutrition was started on the 3rd day posttraumatically. Sampling was performed on the 7th day posttraumatically. Nitrogen balances were significantly different in all three groups, being lowest in group III. Scalded rats fed isonitrogenously, but with different amounts of glucose showed only minor changes in AA concentrations. However scalded rats fed with a nitrogen-free diet exhibited significantly reduced total muscle and liver AA levels. These decreased AA levels were due to a drop of glycine in the muscle tissue (74%) and liver (49%). Contrary to the clinical catabolic situation in scalded and starved rats, it was not intracellular glutamine but glycine which was considerably influenced by catabolism and starvation.
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PMID:Effects of nutrition on plasma, liver and muscle amino acids in scalded rats. 309 64

The addition of DL-7-azatryptophan (AZAT), a tryptophan analog, to continuous cultures of Anabaena sp. strain CA grown with 10 mM nitrate as the nitrogen source resulted in the differentiation of heterocysts. Analysis of the intracellular amino acid pools of Anabaena sp. strain CA after the addition of AZAT showed a marked decline in the intracellular glutamate pool and a slight increase in the levels of glutamine. The in vitro activity of glutamate synthase, the second enzyme involved in primary ammonia assimilation in Anabaena spp., was partially inhibited by the presence of AZAT at concentrations which are effective in triggering heterocyst formation (15% inhibition at 10 microM AZAT and up to 85% inhibition at 1.0 mM AZAT). Azaserine, a glutamine analog and potent glutamate synthase inhibitor, had no effect on the triggering of heterocyst development from undifferentiated batch and continuous cultures of Anabaena sp. strain CA. However, the presence of 1.0 microM azaserine significantly decreased the intracellular glutamate pool and increased the glutamine pool. The addition of AZAT also caused a decrease in the C-phycocyanin content of Anabaena sp. strain CA as a result of its proteolytic degradation. AZAT also had an inhibitory effect on the nitrogenase activity of Anabaena sp. strain CA. All these results suggest that AZAT causes a general nitrogen starvation of Anabaena sp. strain CA filaments, triggering heterocyst synthesis.
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PMID:Nitrogen starvation mediated by DL-7-azatryptophan in the cyanobacterium Anabaena sp. strain CA. 310 56

Skeletal muscle intracellular amino acids and transmembrane potential difference (Em) were measured in hospitalized volunteers during starvation and refeeding with total parenteral nutrition (TPN). Healthy volunteers underwent extremity amino acid flux measurement, percutaneous skeletal muscle biopsy and determination of skeletal muscle Em after ten days of starvation (ST), and after a subsequent ten day period of TPN. ST produced a significant (p less than 0.05) decrease in plasma essential amino acids when compared with normal ambulatory volunteers. Subsequent administration of TPN produced a significant extremity uptake of all essential amino acids except for threonine and uptake of the nonessential amino acids taurine, glutamate, tyrosine and arginine. ST produced a significant reduction in skeletal muscle free intracellular glutamine and a significant increase in isoleucine and leucine. These changes in free intracellular amino acids were not reversed by administration of TPN. At the conclusion of ten days of ST and ten days of TPN, there was a significant reduction (p less than 0.05) in skeletal muscle Em. The results demonstrate that abnormalities of intracellular amino acid concentrations and reduction of muscle Em are not specific to stress conditions, but rather they can be present during both unstressed ST and intravenous nutritional repletion.
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PMID:The effect of starvation and total parenteral nutrition on skeletal muscle amino acid content and membrane potential difference in normal man. 312 18

Muscle glutamine concentration ([GLN]) and protein synthesis rate (Ks) have been examined in vivo in well-fed, protein-deficient, starved, and endotoxemic rats. With protein deficiency (8 or 5% casein diet), [GLN] fell from 7.70 to 5.58 and 3.56 mmol/kg in the 8 and 5% diet groups, with Ks falling from 15.42 to 9.1 and 6.84%/day. Three-day starvation reduced [GLN] and Ks to 2.38 mmol/kg and 5.6%/day, respectively. In all these groups food intakes and insulin were generally well maintained (except in the starved group), whereas free 3,5,3'-triiodothyronine (T3) was depressed in the starved and 5% protein group. The E. coli lipopolysaccharide endotoxin (3 mg/kg) reduced [GLN] to 5.85 and 4.72 mmol/kg and Ks to 10.5 and 9.10%/day in two well-fed groups. Insulin levels were increased, and free T3 levels fell. Combined protein deficiency and endotoxemia further reduced [GLN] and Ks to 1.88 mmol/kg and 4.01%/day, respectively, in the 5% protein rats. Changes in both ribosomal activity (KRNA) and concentration (RNA/protein) contributed to the fall in Ks in malnutrition and endotoxemia, although reductions in the RNA concentration were most marked with protein deficiency and reductions in the KRNA dominated the response to the endotoxin. The changes in [GLN] and Ks were highly correlated as were [GLN] and both KRNA and the RNA concentration, and these relationships were unique to glutamine. These relationships could reflect sensitivity of glutamine transport and protein synthesis to the same regulatory influences, and the particular roles of insulin and T3 are discussed, as well as any direct influence of glutamine on protein synthesis.
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PMID:Relationship between glutamine concentration and protein synthesis in rat skeletal muscle. 313 58

1. The effect of starvation on the metabolism of gut glutamine and ketone-bodies of peak lactating, non-lactating and virgin rats was investigated. 2. The arterial blood ketone-body concentration was increased by approximately 7-, 6- and 13-fold in 48 h-starved virgin, non-lactating and lactating rats, respectively. 3. The arterial blood glutamine concentration was decreased by approximately 32% in 48 h-starved lactating rats (p less than 0.001). 4. The maximal activity of phosphate-dependent glutaminase was increased or decreased in the small intestine of fed or 48 h-starved peak-lactating rats, respectively. 5. Portal drained viscera blood flow increased by approximately 25% in peak-lactating rats. 6. Arteriovenous difference measurements for ketone-bodies across the gut of 48 h-starved rats showed an increase in net uptake of ketone-bodies by approximately 10-, 17- and 29-fold in virgin, non-lactating and lactating rats, respectively. 7. Glutamine was extracted by the gut of peak-lactating rats at a rate of 487 nmol/100 g of body wt. which was greater by approximately 33% (p less than 0.001) than that of virgin or non-lactating animals. In peak lactating rats, 48 h-starvation resulted in marked decreases in the rates of glutamine removal from the circulation (p less than 0.001) which was accompanied by decreased rates of release of glutamate, alanine and ammonia.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Glutamine and ketone-body metabolism in the small intestine of starved peak-lactating rats. 313 91


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