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

Na+-K+-stimulated and Mg++-dependent ATPase activities were investigated in the developing cerebral cortex, subcortical structures, and medulla oblongata of rats as was the effect of 24-hr lasting starvation and thirst on those enzyme activities. We found (a) a developmental increase of these ATPase activities in the developing rat brain with the maximum in the cerebral cortex and with the minimum in the medulla oblongata; (b) a decrease of the ratio of these enzyme activities, which was near unity in adult animals; (c) an increase of ATPase activities in the cerebral cortex and subcortical formations of young rats under starvation conditions followed by a decrease of the Mg++/Na+-K+-ATPase activity ratios in these structures; and (d) a decrease of these activities, especially in the cerebral cortex, and an increase of the activity ratios in adult animals under starvation conditions.
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PMID:Influence of age and short-term starvation on the ATPase activity in the developing rat brain. 21 66

1. The levels of the individual free amino acids, K, Na and water present in parietal muscle were measured in fish starved for periods of 3-115 days. 2. The Na and water content progressively increased relative to dry weight of tissue during the starvation period whereas an initial increase in the K content up to 67 days was followed by a decrease to near the normal fed level by 115 days. The ammonia content remained essentially stable over the same period. 3. The essential free amino acid content tended to follow the muscle sodium pattern while the non-essential amino acids and taurine gave results somewhat similar to those of potassium. 4. The net result of these changes is that the Na, K and total free amino acid concentration is maintained within fairly narrow limits relative to the tissue water content during 11-67 days of the starvation period under the experimental conditions used.
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PMID:The effects of starvation on the sodium, potassium, water and free amino acid content of parietal muscle from Agonus cataphractus. 31 60

The development of resistance to amphotericin methyl ester, measured in terms of the amount of drug required to induce a standard rate of release of K+ from suspensions of washed organisms, has been followed in Candida albicans in starved cultures under controlled conditions of aeration, stirring and temperature. Resistance develops at a rate which increases with the rate of aeration, limited by the onset of damage due to turbulence. Resistance decreases rapidly if gassing with N2 is substituted for aeration, but sensitivity does not reach that of exponentially growing cells. Resumption of aeration is followed by a slow recovery of resistance. The addition of inhibitors of protein synthesis (trichodermin, verrucarin) or uncoupling agents (2,4-dinitrophenol, sodium azide) at the beginning of starvation results in an increased rate of development of resistance. Adding inhibitors at a later stage, when resistance has developed after 72 h aeration, does not affect the decrease in resistance produced by gassing with N2 but the presence of trichodermin or verrucarin delays the recovery of resistance o
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PMID:The effect of aeration and metabolic inhibitors on resistance to amphotericin in starved cultures of Candida albicans. 32 78

Rates of uptake of glucose (measured with 3H-2-deoxy-d-glucose), galactose, and leucine after exposure of chick embryo cells to increasing concentrations of Na+ over the range 100 to 200 mM. Uptake of nucleosides was unaffected by [Na+] over this range. Prior exposure of cells was required for the [Na+] effect on uptake. Changes were measureable within two hours after changing [Na+], and although the capacity for deoxyglucose uptake remained constant thereafter, the capacity for leucine uptake continued to change during the next few hours. Inhibition of protein synthesis by cycloheximide, or of RNA synthesis by Actinomycin D, failed to prevent these uptake changes. Analysis of the kinetics of uptake showed that only the Km for uptake of deoxyglucose or leucine was affected by [Na+]; the maximum V for each compound remained the same. Effects of [Na+]; could be distinguished from the increased capacity for glucose uptake induced by glucose starvation. Incorporation of both radioactive uridine into RNA, and radioactive thymidine into DNA, were affected by [Na+[, but the differences were not correlated with uptake of other metoblites. No differences in countable mitoses were apparent, although the growth of chick embryo cells in increased slightly with increasing [Na+]. Changes in uptake due to differing [Na+] also were observed in mammalian (rat NRK) cells. However, no effects of [Na+] on rates of cell growth or saturation density were observed with these cells.
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PMID:Sodium concentrations affect metabolite uptake and cellular metabolism. 56 84

The effects of a six day starvation regimen on rats' hearts were studied by electron microscopy in combination with marker-enzyme assays of density-sedimentation (rho-S) zonal centrifugation fractions, and with Na+, K+ and Ca++ determinations of sera and heart homogenates. The evidence suggested that massive intracellular cardiac destruction occurred by two pathways. One pathway was seen by electron micrography in which proliferation of lysosomal populations was demonstrated. The finding was confirmed biochemically by increased activities of lysosomal acid hydrolases, particularly cathepsin D. The second pathway was deduced from biochemical and electrolytic data. It was believed to have been initiated by cellular K+ retention, which provided the acid milieu required for intracellular Ca++ retention. It is postulated that the resulting increase in Ca++ activated the loosely-bound membrane neutral (pH 7.4), and alkaline (pH 8.5) proteases, causing subcellular autolysis, particularly involving mitochondria, myofibrils and sarcoplasmic reticulum.
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PMID:Effects of starvation on vacuolar apparatus of cardiac muscle tissue determined by electron microscopy, marker-enzyme assays and electrolyte studies. 61 Oct

Bdellovibrio peptidoglycan is of typical gram-negative composition. The molar ratios of alanine:glutamic acid:diaminopimelic acid:muramic acid:glucosamine were about 2:1:1:1:1. Nascent, nongrowing Bdellovibrio bacteriovorus 109J were converted from highly motile vibrios to highly motile spheres when shaken in dilute buffer plus penicillin, cephalothin, bacitracin, or D-cycloserine. The spherical forms contained essentially no sedimentable peptidoglycan; i.e., they were spheroplasts. Spheroplasts induced by penicillin, D-cycloserine, and lysozyme were stable in dilute buffer and did not lyse when subjected to osmotic shock. Normal Bdellovibrio suspended in buffer turned over their peptidoglycan at a rate of approximately 30% h during the initial 120 min of starvation. Chloramphenicol and sodium azide strongly inhibited Bdellovibrio peptidoglycan turnover and the induction of spheroplasts by penicillin. The data indicate that nongrowing B. bacteriovorus are sensitive to penicillin and other antibiotics affecting cell walls because of their high rate of peptidoglycan turnover. It is also concluded that an intact peptidoglycan layer is required for maintaining cell shape, but is not required for osmotic stability of B. bacteriovorus.
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PMID:Penicillin-induced formation of osmotically stable spheroplasts in nongrowing Bdellovibrio bacteriovorus. 64 Oct 13

The phenomenon of natriuresis during the early phase of total starvation has been described in man and rabbit. We have examined the pattern of electrolyte excretion initiated by starvation for 4 days in the male Wistar rat. Within 24 hr sodium excretion is significantly diminished when compared to prestarvation values (control 2.55 +/- 0.76 [S.D.] mEq/day; 1-day fast 0.42 +/- 0.27) and by day 2 is less than one tenth of the control value. Chloride retention parallels this sodium conservation. Concomitant changes in urinary pH and ammonia excretion (UNH4V) reflect the mild acidosis of starvation (control pH 7.46 +/- 0.18 [S.D.], UNH4V 0.21 +/- 0.08 [S.D.] mEq/day; day 2 pH 6.10 +/- 0.31, UNH4V 0.71 +/- 0.21). However, the excretion of organic acids is not elevated but is actually decreased by day 2 (control 1.02 +/- 0.21 [S.D.] mEq/day; day 2 0.66 +/- 0.26). The majority of the organic acids are excreted as salts (day-2 0.51 +/- 0.21). This level of excretion does not obligate excessive sodium loss and can be adequately matched by renal ammonia production. Normal plasma glucose levels are maintained, consistent with the well-documented increase in renal gluconeogenesis in the starved rat. Plasma levels of glucagon, a known natriuretic and ketogenic agent, do not rise, and this together with a normal plasma glucose concentration may account for the failure of the rat to exhibit the natriuresis of starvation that is observed in man and rabbit.
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PMID:Renal sodium conservation during starvation in the rat. 64 88

Clinical observations suggest that overt rhabdomyolysis may occur if severe hypophosphatemia is superimposed upon a pre-existing subclinical myopathy. To examine this possibility, a subclinical muscle cell injury was induced in 23 dogs by feeding them a phosphorus- and calorie-deficient diet until they lost 30% of their original weight. To induce acute, severe hypophosphatemia in the animals after partial starvation, 17 of the dogs were given large quantities of the same phosphorus-deficient diet in conjunction with an oral carbohydrate supplement, which together provided 140 kcal/kg per day. After phosphorus and caloric deprivation, serum phosphorus and creatine phosphokinase (CPK) activity were normal. Total muscle phosphorus content fell from 28.0+/-1.3 to 26.1+/-2.5 mmol/dg fat-free dry solids. Sodium, chloride, and water contents rose. These changes resembled those observed in patients with subclinical alcoholic myopathy. When studied after 3 days of hyperalimentation, the animals not receiving phosphorus showed weakness, tremulousness, and in some cases, seizures. Serum phosphorus fell, the average lowest value was 0.8 mg/dl (P <0.001). CPK activity rose from 66+/-357 to 695+/-1,288 IU/liter (P <0.001). Muscle phosphorus content fell further to 21.1+/-7.7 mmol/dg fat-free dry solids (P <0.001). Muscle Na and Cl contents became higher (P <0.01). Sections of gracilis muscle showed frank rhabdomyolysis.6 of the 23 phosphorus- and calorie-deprived dogs were also given 140 kal/kg per day but in addition, each received 147 mmol of elemental phosphorus. These dogs consumed their diet avidly and displayed no symptoms. They did not become hypophosphatemic, their CPK remained normal, and derangements of cellular Na, Cl, and H(2)O were rapidly corrected. The gracilis muscle appeared normal histologically in these animals. These data suggest that a subclinical myopathy may set the stage for rhabdomyolysis if acute, severe hypophosphatemia is superimposed. Neither acute hypophosphatemia nor rhabdomyolysis occur if abundant phosphorus is provided during hyperalimentation.
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PMID:Hypophosphatemia and rhabdomyolysis. 74 77

Pregnancies in pigs were sustained during periods of prolonged starvation in spite of maternal body weight losses exceeding 40 kg. Maternal stores of protein were made available for feto-placental development during starvation of the dam. Concentrations of maternal serum proteins, urea nitrogen, electrolytes, and iron were determined in sequential blood samples of healthy Yorkshire pigs during a prolonged period of 40 days inanition (water only) in either the middle third (days 30-70) or last third (days 70-110). Serum protein levels remained similar to full-diet controls throughout these two periods, whereas serum concentrations of albumin and urea N increased primarily during the last third of gestation in starved dams. Serum Na+ levels declined during prolonged inanition while Ca2+ increased and K+ remained unchanged. It was only near term that Fe2+ levels decreased in those dams starved during a period of 40 days in the last third of pregnancy. These results indicated that maternal serum components were sustained at adequate levels to maintain normal development of conceptuses during prolonged starvation in either the middle third or last third of pregnancy in the pig.
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PMID:Maternal serum metabolites during prolonged starvation in pregnant pigs. 76 46

The proteins synthesized by arginine-requiring Escherichia coli during growth or arginine starvation were characterized by polyacrylamide gel electrophoresis in sodium dodecyl sulfate to give size distributions. The proteins made during amino acid starvation were smaller than those made by growing cells. This was true for otherwise isogenic rel- ("relaxed") and rel+ ("stringent") bacteria. Also using electrophoretic profiles, the peptide chain growth rate was estimated by a novel method based on comparison of theoretically predicted and observed kinetics of pulse labeling protein chains of different sizes. During arginine starvation, the rate was 2--5 amino acids/s for both rel- and rel+ cells, compared to 20 amino acids/s for growing cells. The results rule out chain growth-rate differences as an aspect of the "relaxed" phenomenon.
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PMID:The polypeptide chain growth rate in amino acid-starved Escherichia coli determined by a novel method. 76 70


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