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

Escherichia coli was exposed to partial pyrimidine starvation by feeding a pyrBI strain orotate as the only pyrimidine source. Subsequently, differential rates of synthesis of rRNA and of a few ribosome-associated proteins as well as the pool sizes of nucleoside triphosphates and ppGpp were measured. As the orotate concentration in the medium was reduced, the growth rate decreased and the pools of pyrimidine nucleotides, particularly UTP, declined. We did not observe the normal inverse relation between concentration of ppGpp and growth rate; rather, we observed that the ppGpp pool was low at slow growth rates. Upshifts in growth rate were made by adding uracil to a culture growing slowly on orotate. Downshifts could be provoked by adding aspartate plus glutamate to a culture growing at a high concentration of orotate. Following the upshift, both the rates of synthesis of the ribosomal components and the pool of ppGpp increased rapidly, while they all decreased after the downshift. These results are discussed in relation to the role of ppGpp in the growth rate control and the stringent response.
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PMID:An unusual correlation between ppGpp pool size and rate of ribosome synthesis during partial pyrimidine starvation of Escherichia coli. 170 3

Effect of hypothalamic lesions on regulation of body weight and fat cell dynamics in obese mice were examined during refeeding after prolonged food deprivation. Obese mice, which were treated with monosodium glutamate for 5 postnatal days and had ventromedial nuclear lesions in the hypothalamus, were used. When adult obese mice were given a glucose electrolyte solution for 20-40 days, the body weight dropped to about 45% of their pre-treatment weight. After reinstituted feeding of normal mouse food ad libitum, their body weight and adipose tissue weight returned to pre-starvation level. Tritiated thymidine autoradiography revealed that cell proliferation occurred in the early stages of refeeding and some fat cells were renewed in the epididymal adipose tissue. Fat cell renewal was found more active in the experimental group than in the control. Thereafter, fat cell size increased gradually via fat storage. These obese mice were found to have the capacity to regulate their body weight and adipose tissue not only through fat storage but also by increasing number of fat cells, in order to replace the cells which were lost during starvation. Therefore, ventromedial nuclear lesion in the hypothalamus does not influence the regulatory mechanism of adipose tissue during starvation and refeeding.
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PMID:Adipocyte dynamics in hypothalamic obese mice during food deprivation and refeeding. 180 74

400 MHz 1H NMR spectroscopy was used to analyze methyl group-containing metabolites in perchloric acid extracts of livers of rats treated with carbon tetrachloride or fed with ethanol-containing liquid diets, and sacrificed with carbon dioxide anoxic euthanasia or pentobarbital euthanasia (with or without 12-18 hour fasting). In all cases, coenzyme A was detected using 1H NMR spectroscopy, but at higher levels for chronic ethanol-treated rats. Propionate was also detected in livers 6 hours after treatment with carbon tetrachloride. The assignments of the 1H NMR resonances in a spectrum of biological origin to these two metabolites have not been previously reported. Another unusual metabolite, 1,2-propanediol, was also observed in dramatically elevated levels in starved rats. The methyl groups for coenzyme A, propionate, and 1,2-propanediol have 1H NMR chemical shifts at 0.73 and 0.87 ppm, 1.18 ppm, and 1.14 ppm (from tetramethylsilane) respectively. In addition to the above mentioned resonances, glutamine, glutamate, proline, acetate, leucine, alanine, lactate, ethanol, beta-hydroxybutyrate, and valine were also observed in the 0.5-2.3 ppm methyl region of the 1H NMR spectra. Biochemical changes were also observed in these latter metabolites. beta-Hydroxybutyrate was increased by chronic ethanol administration; this increase was exacerbated by starvation. Alanine was decreased by chronic ethanol administration. Acetate was increased by chronic ethanol administration except when glycerol was added to the liver or when the rat was starved. We also observed an unassigned triplet at 0.81 ppm, and its appearance seems to be correlated with that of 1,2-propanediol.
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PMID:1H NMR analyses of methyl group-containing metabolites in rat liver extracts--effects of starvation, anoxia, acute glycerol and carbon tetrachloride treatment and chronic ethanol administration on hepatic metabolism. 181 3

The cephalic gustatory stimuli during a meal yield nutritional information and aid in the efficient control of homeostasis. This study was focused on either appetite for flavored food or feeding behavior in growing male Sprague-Dawley rats under various states of protein nutrition. In fasted rats, endogenous protein degradation was suppressed by ingestion of glucose that was sufficient to meet energy needs. The decrease in the amount of diet intake was compensated by sugar ingestion, except for sucrose. Rats that ingested sucrose exceeded 115% of total energy intake, compared to ingestion of saccharin as a control. Appetite and meal size are primarily dependent upon the dietary protein level, whether it was beyond normal requirements or not and, thus, flavoring by certain taste material is effective for a diet sufficient in protein, but not for a deficient one. In addition, rats fed a diet containing amino acids preferred saccharin and monosodium L-glutamate (MSG) and grew normally. But, when L-tryptophan-deficient diet was offered, the preference for tryptophan was elicited, and then MSG intake was elevated and their growth became normal. However, preference for saccharin never occurred because the level of tryptophan in blood fluctuated and was not maintained within normal limits. The strong preference for sweetness that is evoked by starvation is directly regulated by the negative energy balance. The animals' primary concern was energy intake and their second concern was protein nutrition, regardless of flavoring.
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PMID:Appetite and taste preference in growing rats given various levels of protein nutrition. 195 39

It has been found that there exists a correlation in the dynamics of changes in the amount of glutamate, alpha-ketoglutarate, glutamine, ammonia and activity level or alpha-ketoglutarate dehydrogenase, NADP-glutamate dehydrogenase, glutamine synthetase and glutaminase in the brain of young carp in the process of winter starvation. It has been stated that under condition of energy deficiency and meaningful amount of ammonia in the organism of hibernating fish, its binding parallel with the known glutamine synthetase mechanism may proceed in the course of the NADP-glutamate dehydrogenase reaction which balance is shifted towards the glutamate synthesis. This reaction is supposed to provide the outflow of alpha-ketoglutarate from the citric cycle, which intensifies energy deficiency of the organism.
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PMID:[Features of the interconversion of alpha-ketoglutarate--glutamate in brain mitochondria of exothermic animals during hibernation]. 198 77

We review evidence for a pathway by which specific cytosolic proteins are targeted to lysosomes for degradation in cultured cells in response to serum withdrawal. This pathway is also activated by starvation in several rat tissues. The enhanced degradation is specific for a class of intracellular proteins containing peptide sequences related to residues 7 to 11 of ribonuclease A (RNase A). The amino acid sequence of this pentapeptide is lysine-phenylalanine-glutamate-arginine-glutamine, or, in single letter amino acid abbreviations, KFERQ. A heat shock protein of 73 kDa binds to such peptide regions in proteins and somehow mediates their transfer to lysosomes for degradation. The recent reconstitution of this lysosomal pathway of proteolysis in vitro should permit detailed mechanistic analysis of how proteins are directed to and translocated across lysosomal membranes.
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PMID:Targeting of cytosolic proteins to lysosomes for degradation. 207 87

Absolute starvation during 2 days induces increased levels of taurine, phosphoethanolamine, ethanolamine, glycine, serine, threonine and decreased levels of aspartate, lysine, methionine and cystine in the rat liver. The ration of nonessential to essential, and glycogenic to ketogenic amino acids increased on the average by 30%. On day 4 of starvation the level of nonessential glycogenic amino acids is significantly lowered, while the concentration of essential ketogenic amino acids is increased. On day 6 essential ketogenic amino acid pool is more increased. On day 10 the shifts in the amino acid pool in the liver are retained, the reduction of alanine and serine content is most typical. The value of D2-Machalanobis, obtained during lineal discriminant analysis of amino acid pool and space distribution of the signs for the control and starving animals (during 10 days), was lower than that on day 4 and 6 of the experiment. The levels of glycine, serine lysine, leucine, glutamate, alanine and aspartate show the highest information content during such investigation of all the groups of animals.
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PMID:[Formation of free fatty acid pool in the liver of rats during starvation]. 227 22

1. Adult, female Xenopus laevis were subjected to 12 months of starvation. 2. Starvation resulted in a continuous reduction in the activity of both hepatic and renal glucose-6-phosphate dehydrogenase. 3. Fructose-1,6-diphosphatase was significantly reduced at months 10 and 12 in the liver, and at months 4, 10, and 12 in the kidney. 4. Pyruvate kinase activity of muscle and liver decreased during the experimental period whereas the renal enzyme remained essentially unchanged. 5. Both hepatic and renal glutamate-pyruvate transaminase (GPT) and hepatic glutamate-oxaloacetate transaminase (GOT) showed a reduction of activity after 2 and 4 months of starvation followed by an increase in GPT but not in GOT.
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PMID:Long-term starvation in Xenopus laevis Daudin--III. Effects on enzymes in several tissues. 255 3

In submerged grown hyphae of Penicillium cyclopium the activities of seven transport systems could be distinguished which share in the uptake of L-arginine, L-glutamic acid, L-phenylalanine and L-leucine. They include the specific systems a (accepting L-arginine and L-lysine), b (L-phenylalanine, L-tyrosine), c (L-glutamic acid) and d (L-leucine), system I (a 'general amino-acid permease') and the low-affinity systems II and III, which accept acidic or basic amino acids, respectively, but also L-phenylalanine. In nutrient-sufficient cells, systems I, II and III remain repressed; uptake is dominated by the specific systems b, c, d and a, the latter reaching its maximum activity. Nitrogen starvation is the most powerful signal for the development of systems I, II and III, whereas, in carbon-starved cells, systems b, c and d reach maximum activities. The development of the general amino-acid permease in nitrogen-starved cells requires both translational and--with a few hours delay--transcriptional events as indicated by the influence of cycloheximide and 5-fluorouracil. The uptake of all amino acids is accompanied by a transient acidification of the cellular interior. Short-time preaccumulation of several anions, such as citrate, alpha-oxo-glutarate, glutamate (but not glutamine), increases the initial rate of amino-acid uptake at a pH above the optimum. Uncouplers inhibit the uptake not only under aerobic but also under anaerobic conditions, where the ATP content is not influenced by these compounds. These findings point to an H+/amino acid symport, which is tightly connected with the recycling of the incoming protons by the plasmalemma H+-ATPase.
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PMID:Kinetic properties, nutrient-dependent regulation and energy coupling of amino-acid transport systems in Penicillium cyclopium. 256 28

The respiratory properties of isolated rat renal mitochondria after fasting conditions (2-8 days) are estimated in comparison with the parameters of normal feeded control animals. After an extrem starvation time of 8 days the active and uncoupled respiration of glutamate/malate, but not of succinate were reduced, whereas the respiratory control index and the ADP/O-Quotient did remain unchanged. In conclusion, malnutrition do not influence the renal function due to mitochondrial changes.
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PMID:[Functional properties of isolated kidney mitochondria of rats in food deprivation]. 256 21


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