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

A method is introduced for the assay of alkaline phosphatase in homogenates of cultured human skin fibroblasts. In a first group of 11 strains, a four- to fifteen-fold increase of enzyme activity is consistently observed following a period of starvation. In the remaining 31 cell-strains similar specific activities of alkaline phosphatase are found irrespective of medium changes. In regularly fed cultures, an inverse exponential correlation between the specific activity of alkaline phosphatase and the age of the donor has been detected.
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PMID:Akaline phosphatase: activity and variation in human diploid fibroblasts. 8 60

Starvation overnight and starvation for 48 h reduced the weight and the protein content of mucosal scrapings, but only minimally reduced the DNA content of the mucosal scrapings. The activity of sucrase and maltase was reduced by both periods of starvation. The activity of lactase and of acid and alkaline phosphatase, however, was less subject to starvation. There were striking differences in the response to starvation between the proximal, mid and distal third of the small intestine. The importance of the proper reference system was discussed.
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PMID:Effect of starvation on small intestinal enzyme activity in germ-free rats. 10 66

A 1-mg/ml amount of threonine (8.4 mM) inhibited growth and sporulation of Bacillus subtilis 168. Inhibition of sporulation was efficiently reversed by valine and less efficiently by pyruvate, arginine, glutamine, and isoleucine. Inhibition of vegetative growth was reversed by asparate and glutamate as well as by valine, arginine, or glutamine. Cells in minimal growth medium were inhibited only transiently by very high concentrations of threonine, whereas inhibition of sporulation was permanent. Addition of threonine prevented the normal increase in alkaline phosphatase and reduced the production of extracellular protease by about 50%, suggesting that threonine blocked the sporulation process relatively early. 2-Ketobutyrate was able to mimic the effect of threonine on sporulation. Sporulation in a strain selected for resistance to azaleucine was partially resistant. Seventy-five percent of the mutants selected for the ability to grow vegetatively in the presence of high threonine concentrations were found to be simultaneously isoleucine auxotrophs. In at least one of these mutants, the threonine resistance phenotpye could not be dissociated from the isoleucine requirement by transformation. This mutation was closely linked to a known ilvA mutation (recombination index, 0.16). This strain also had reduced intracellular threonine deaminase activity. These results suggest that threonine inhibits B. subtilis by causing valine starvation.
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PMID:Inhibition of Bacillus subtilis growth and sporulation by threonine. 10 59

The effect of exogenous orthophosphate and mutations in genes, regulating the Pi transport system, on the ATPase activity of E. coli subcellular fractions was studied. It was shown that the orthophosphate starvation resulted in the cessation of the increase in the ATPase activity of membranes and was accompanied by the increase in the analogous activity of a soluble fraction at the expense of the derepression of alkaline phosphatase possessing this activity. The disturbance, resulted from the mutation of protein components participating in the specific binding and transport of orthophosphate, changed the ATPase activity of subcellular fractions: increased the ATPase activity of soluble fraction (independently of the presence of orthophosphate in medium), did not affect significantly the activity of membrane--bound ATPase in the presence of orthophosphate and decreased this activity in the absence of orthophosphate. The data obtained point to the fact that components, binding exogenous orthophosphate and transporting it into a cell, affect the rigidity of the ATPase bound E. coli cytoplasmic membrane. Mutations resulting in the defect in these components relax this bound and lead to the detection of ATPase proper in the periplasm.
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PMID:[Exogenous orthophosphate regulation of ATPase activity of E. coli cells]. 15 76

The regulation of three Salmonella typhimurium phosphatases in reponse to different nutritional limitations has been studied. Two enzymes, an acid hexose phosphatase (EC 3.1.3.2) and a cyclic phosphodiesterase (EC 3.1.4.d), appear to be regulated by the cyclic adenosine 3' ,5'-monophosphate (AMP) catabolite repression system. Levels of these enzymes increased in cells grown on poor carbon sources but not in cells grown on poor nitrogen or phosphorus sources. Mutants lacking adenyl cyclase did not produce elevated levels of these enzymes in response to carbon limitation unless cyclic AMP was supplied. Mutants lacking the cyclic AMP receptor protein did not produce elevated levels of these enzymes in response to carbon limitation regardless of the presence of cyclic AMP. Since no specific induction of either enzyme could be demonstrated, these enzymes appear to be controlled solely by the cyclic AMP system. Nonspecific acid phsphatase activity (EC 3.1.3.2) increased in response to carbon, nitrogen, phosphorus, or sulfur limitation. The extent of the increase depended on growth rate, with slower growth rates favoring greater increases, and on the type of limitation. Limitation for either carbon or phosphorus resulted in maximum increases, whereas severe limitation of Mg2+ caused only a slight increase. The increase in nonspecific acid phosphatase during carbon limitation was apparently not mediated by the catabolite repression system since mutants lacking adenyl cyclase or the cyclic AMP receptor protein still produced elevated levels of this enzyme during carbon starvation. Nor did the increase during phosphorus limitation appear to be mediated by the alkaline phosphatase regulatory system. A strain of Salmonella bearing a chromosomal mutation, which caused constitutive production of alkaline phosphatase (introduced by an episome from Escherichia coli), did not have constitutive levels of nonspecific acid phosphatase.
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PMID:Regulation of two phosphatases and a cyclic phosphodiesterase of Salmonella typhimurium. 19 13

Comprehensive investigations were carried out for establishing the biological and nutritional value of low erucic-acid rapeseed oil from a variety of rape called Janpol selected in Poland. The pathophysiological effects of Janpol rapeseed oil were observed after giving it as the only source of fat in the diet or added in different proportions to other edible fats. In all cases the total amount of fat in the diet was 20 p. 100 kcal. The investigations were carried out on 78 young male Wistar rats aged 25 days at the beginning of the experiment. The rats were divided into 7 groups and they were given diets containing: 1) soybean oil; 2) mixed fats; 3) rapeseed oil of high erucic-acid content; 4) mixed fats containing 25 p. 100 of Janpol rapeseed oil; 5) mixed fats with 50 p. 100 of Janpol rapeseed oil; 6) mixed fats with 75 p. 100 of Janpol rapeseed oil; 7) Janpol rapeseed oil only. The experiment lasted 3 months. After its completion the rats were decapitated after 18 hours of starvation. The investigation s included : determination of weight gain, determination of the weight of selected organs (liver-lungs, heart, kidneys, testes, spleen), determination of alkaline phosphatase and pseudocholinesterase activity in the serum, determination of triglycerides and cholesterol in the serum, tests for adrenocortical function, histo-chemical investigations of the liver (alkaline and acid phosphatase, adenosine triphosphatase, fatty infiltration of the liver), macroscopic and microscopic anatomopathological examinations. The authors found the Janpol rapeseed oil caused less pronounced changes in the determined indices of the biological and nutritional evaluation as compared with high-erucic-acid rapeseed oil. Janpol repeseed oil given to experimental animals mixed with other fats in proportions of 25 p. 100 and 50 p. 100 of all fats in the diet, that is 5 p. 100 and 10 p. 100 kcal in the diet derived from Janpol oil gave in most determinations of the investigated parameters results very similar to those observed in animals receiving soybean oil. The results of these investigations show that Janpol rapesed oil can be used for nutrition of man in amounts not exceeding 10 p. 100 of the total caloric content of food.
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PMID:[Nutritional and biological experiences on low-erucic acid rapeseed oil "Janpol". Studies on rats after ingestion of "Janpol" oil and other edible fats]. 22 Sep

The phosphorus contents of acid-soluble pools, lipid, ribonucleic acid, and acid-insoluble polyphosphate were lowered in Synechococcus in proportion to the reduction in growth rate in phosphate-limited but not in nitrate-limited continuous culture. Phosphorus in these cell fractions was lost proportionately during progressive phosphate starvation of batch cultures. Acid-insoluble polyphosphate was always present in all cultural conditions to about 10% of total cell phosphorus and did not turn over during balanced exponential growth. Extensive polyphosphate formation occurred transiently when phosphate was given to cells which had been phosphate limited. This material was broken down after 8 h even in the presence of excess external orthophosphate, and its phosphorus was transferred into other cell fractions, notably ribonucleic acid. Phosphate uptake kinetics indicated an invariant apparent K(m) of about 0.5 muM, but V(max) was 40 to 50 times greater in cells from phosphate-limited cultures than in cells from nitrate-limited or balanced batch cultures. Over 90% of the phosphate taken up within the first 30 s at 15 degrees C was recovered as orthophosphate. The uptake process is highly specific, since neither phosphate entry nor growth was affected by a 100-fold excess of arsenate. The activity of polyphosphate synthetase in cell extracts increased at least 20-fold during phosphate starvation or in phosphate-restricted growth, but polyphosphatase activity was little changed by different growth conditions. The findings suggest that derepression of the phosphate transport and polyphosphate-synthesizing systems as well as alkaline phosphatase occurs in phosphate shortage, but that the breakdown of polyphosphate in this organism is regulated by modulation of existing enzyme activity.
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PMID:Regulation of phosphate accumulation in the unicellular cyanobacterium Synechococcus. 22 42

The influence of starvation has been studied on tissue and serum G-6Pase F-D-Pase and alkaline phosphatase activities and on the muscle and liver glycogen content of the freshwater catfish H. fossilis (Bloch). A marked increase in G-6Pase and F-D-Pase activities and a fall in the muscle and liver glycogen content recorded during 40 day starvation. The rise in gluconeogenic enzymes during starvation may be due to glucocorticoid stimulation. Alkaline phosphatase activity was found to decline markedly during starvation. The decline in enzyme activity is attributed to some factors like a fall in the rate of synthesis caused by lowered metabolic demands and to electrolyte imbalance caused by tissue overhydration. The fall in glycogen content may be related to the starved condition of the fish. Elevation in glycogen content and alkaline phosphatase activity and a fall in gluconeogenic enzymes were noted when feeding had been resumed.
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PMID:Effect of starvation on tissue and serum gluconeogenic enzymes, alkaline phosphatase and tissue glycogen in the freshwater catfish, Heteropneustes fossilis (Bloch). 23 11

A cyclic nucleotide-binding phosphohydrolase that possesses both a phosphomonoesterase and a phosphodiesterase catalytic function has been partially purified from Aspergillus nidulans. The enzyme hydrolyzes both p-nitrophenylphosphate and bis-(p-nitrophenyl)-phosphate. o'-Nucleoside monophosphates are the best physiological phosphomonesterase substrates but 5'- and 2'-nucleoside monophosphates are also hydrolyzed. The enzyme catalyzes the hydrolysis of adenosine 5'-triphosphate, adenosine 5'-diphosphate, and 2',3'- and 3'5'-cyclic nucleotides, but not of ribonucleic acid, deoxyribonucleic acid, or nicotinamide adenine dinucleotide. The enzyme has acid pH optima and is not activated by divalent cations. Nucleosides and nucleotides inhibit the enzyme. Cyclic nucleotides are competitive inhibitors of the phosphodiesterase-phosphomonoesterase. The enzyme can occur extracellularly. The phosphodiesterase-phosphomonoesterase is present at high levels in nitrogen-starved mycelium, and it is strongly repressed during growth in media containing ammonium or glutamine and weakly repressed during growth in glutamate-containing medium. Experiments with various area mutants show that this regulatory gene is involved in the control of the enzyme. No evidence for regulation of the enzyme by carbon or phosphorus starvation has been found.
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PMID:Enzymology and genetic regulation of a cyclic nucleotide-binding phosphodiesterase-phosphomonoesterase from Aspergillus nidulans. 24 43

The effect of exogenous orthophosphate and mutations in regulatory genes of alkaline phosphatase on the level of nonspecific acid phosphatase was studied. The level of this enzyme as well as the level of alkaline phosphatase were shown to be regulated by exogenous orthophosphate being derepressed under phosphate starvation. The derepression of acid phosphatase is accompanied by more rapid secretion of enzyme from membranes to soluble fraction. Mutations in all the four regulatory genes decrease the level of enzyme in cells. Genes phoR and phoS, participating in regulation of alkaline phosphatase, are required for the derepression of acid phosphatase under the conditions of phosphate starvation.
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PMID:[Interrelationship between metabolic and genetic regulation of alkaline and acid phosphatases in E. coli cells]. 36 75


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