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

Pyruvate kinase and phosphoenolpyruvate carboxykinase activities were determined in microdissected freeze-dried liver cells from the periportal and pericentral area of the liver lobule. Pyruvate kinase activity was measured by a microfluorimetric procedure adapted to 20-200 ng tissue dry weight. In livers from fed rats, its activity was twice as high in the central zone as in the periportal cells; starvation reduced this gradient by decreasing central activities. Phosphoenolpyruvate carboxykinase activity was measured by a microradiochemical technique in 100-300 ng tissue dry weight. In livers from fed rats, this enzyme was nearly 3 times more active in the periportal cells than in the central area. Starvation increased this enzyme in both zones with a more pronounced change in the central cells. The results indicate a heterogeneous distribution of enzymes of carbohydrate metabolism in the liver lobule. Gluconegenesis seems to be localized preferentially in periportal hepatocytes, whereas the glycolytic enzyme was found to be more active in cells surrounding the pericentral liver cells.
Hoppe Seylers Z Physiol Chem 1976 Dec
PMID:Liver cell heterogeneity. The distribution of pyruvate kinase and phosphoenolpyruvate carboxykinase (GTP) in the liver lobule of fed and starved rats. 101 1

In 30 obese subjects three different methods for weight, reduction were applicated over a period of 14 days. One group (n=10) was treated with total starvation, the other group (n=10) with total starvation and 80 mval potassium in addition and the third group (n=10) with a 700 cal. diet. In total starvation the balance of sodium, potassium and phosphate amounted to -9 mval/d, -34,9/d and -8,8 mval/d respectively. Whereas calcium showed a positive balance of 4,4 mval/d. During addition of 80 mval potassium sodium excretion increased whereas potassium excretion was diminished resulting in a potassium balance less negative. During treatment with the 700 calorie diet the highest negative sodium and a high positive potassium balance were observed,
Z Ernahrungswiss 1976 Dec
PMID:[Electrolyte metabolism in obese subjects with various forms of therapy]. 102 Mar 70

Rats fasted for 48-96h before exposure were shown to have a longer survival time at groups 33,500 ft (1 ft = 0.305 m) simulated altitude than nonfasted controls. Although both become hypothermic at 33500 ft, colonic temperatures of the fasted rats were not sufficiently lower than those of nonfasted animals to explain the difference in survival time. The injection of glucose and insulin before exposure almost completely eliminated the protection afforded by fasting, whereas glucose alone had no effect on survival. It is therefore suggested that an alteration in carbohydrate metabolism, possibly in combination with other starvation-induced changes, allowed fasted rats to survive at 33500 ft until declining body temperature reduced metabolic rate to a level compatible with oxygen supply.
Can J Physiol Pharmacol 1976 Dec
PMID:Survial of fasted rats exposed to altitude. 102 Dec 22

In female rats, pretreatment with dexamethasone acetate or triamcinolone reduced the toxicity and plasma concentrations of tetraethylammonium bromide while increasing its level in urine. Pretreatment with corticosterone acetate or pregnenolone-16alpha-carbonitrile shared none of these effects. Although starvation or restraint neither diminished the tetraethylammonium bromide concentrations in plasma nor accelerated its urinary excretion, its toxicity was diminished by the stress induced with spinal cord lesions, heat, cold, hydrocortisone, or reserpine as well as starvation or restraint. The protection offered against the toxicant by stress and by the potent glucocorticoids seemed to be mediated, at least partly, via different mechanisms. Stress-induced resistance to tetraethylammonium bromide could not be attributed to elevated plasma corticosterone levels, whereas glucocorticoid-induced resistance could be partially ascribed to increased urinary excretion of the toxicant.
J Pharm Sci 1976 Dec
PMID:Influence of steroids and stress on toxicity and disposition of tetraethylammonium bromide. 103 75

When thymidine-requiring lexA- strains were starved for thymidine, the kinetics of survival were similar to those of a nearly isogenic lexA+ strain. The size distribution of cells in the lexA- and lexA+ cultures were, however, quite different. Whereas most of the cells in the starved lexA+ cultures grew into long filamentous forms (longer than 4.0 mum), many of the lexA- cells were found to have a normal rod shape (4.0 mum or shorter). It was shown that lexA- cells undergo more divisions during thymidine starvation than lexA+ cells. Furthermore, using an autoradiographic method to analyze deoxyribonucleic acid (DNA) distribution in the starved cells, we demonstrated that cells without DNA are produced in both normal and starved lexA- cultures at a much higher frequency than in lexA+ cultures. Some of these cells may be produced by breakdown of DNA, but we favor the hypothesis that they result from an abnormal cell division process. Since lexA mutations are dominant, we conclude that a diffusible product decreases the synthesis or activity of an inhibitor of cell division in lexA- strains when DNA synthesis is blocked by thymidine starvation.
J Bacteriol 1975 Dec
PMID:Production of cells without deoxyribonucleic acid during thymidine starvation of lexA- cultures of Escherichia coli K-12. 110 71

The fate of the internally formed nucleotides resulting from the degradation of ribonucleic acid was studied. Prelabeled Escherichia coli cells were submitted to carbon starvation, and the acid-soluble products were separated by thin-layer chromatography. It was determined that free bases constitute some 75% of the end product, the balance consisting of nucleoside diphosphates, 5'-nucleoside monophosphates, 3'-nucleoside monophosphates, and nucleosides. The majority of degradation products, including phosphorylated derivatives, were excreted into the medium. The amount of products in the pool remained constant. The soluble products formed by E. coli mutants lacking either 5'-nucleotidase (Ush-) or 3'-nucleotidase (Cpd-) were compared with those produced by the parental strain with both enzymes. The results obtained indicated that 5'-nucleotidase is involved in the degradation of internally foromed nucleotides but that 3'-nucleotidase takes no part in the process.
J Bacteriol 1975 Dec
PMID:Acid-soluble degradation products of ribonucleic acid in Escherichia coli and the role of nucleotidases in their catabolism. 110 75

The unique leucine-, arginine-, valine-, and phenylalanine-specific transfer ribonucleic acids (tRNA's) produced in relaxed-control (rel-) Escherichia coli during leucine or arginine starvation are chromatographically similar to those produced by chloramphenicol treatment. The major unique rel- leucine-specific and phenylalanine-specific tRNA's are heterogeneous, accumulate with time of starvation, and can account for up to 70% of the respective amino acid acceptor activities. The changes which occur in the isoacceptor profiles for tRNALeu and tRNAPhe as a function of starvation time suggest that the unique species are undermodified precursors to the major isoacceptor species observed in nonstarved cells. Analyses of the isoacceptor patterns of tRNA from cells recovering from starvation suggest that the unique species of tRNALeu and tRNAPhe may not be normally occurring precursors. When leucine-starved cells were incubated in fresh, fully supplemented medium, the major unique tRNALeu and tRNAPhe appeared to be converted to normal species only slowly or not at all. The results are consistent with the view that some of the events in the post-transcriptional modification of tRNA may occur in an ordered sequence. An examination of the subcellular distribution of the unique leucine and phenylalanine tRNA's revealed that these species occur on the ribosome at about the same frequency as the major, normally occurring isoacceptor species. This result provides additional evidence of a precursor-product relationship for the unique and normal tRNA's and further indicates that there is no discrimination against the unique species by the ribosome.
J Bacteriol 1975 Dec
PMID:Unbalanced growth and the production of unique transfer ribonucleic acids in relaxed-control Escherichia coli. 110 85

Substantial transfer of R factors occurred in vivo, under certain conditions, in the rumen of adult sheep in the absence of any antibiotic treatment. A starvation period of 24-48 hr. was required to produce the conditions necessary, when even quite low inocula (ca. 10(3) cells) of donor and recipient E. coli could grow within the rumen and reach a population density sufficient for transfer to take place. The results indicate that under the same conditions R factors may be transferred between organisms in the lower intestinal tract also. Without the starvation period, the inoculation of even massive numbers (10(10) cells) of the same organisms resulted in almost no detectable transfer. Some of the experimental animals on which a starvation period was imposed became carriers of either the inoculated recipient E. coli, or of R factor bearing coliforms, and these formed 1-10% of the total coliform population of the faeces for at least 6 weeks.
J Hyg (Lond) 1975 Dec
PMID:In vivo transfer of R factors between Escherichia coli strains inoculated into the rumen of sheep. 110 10

In a thymine-deprived culture, the mutant cells (deficient in dTDP-glucose pyrophosphorylase activity and named Ter-15) lose viability at a faster rate, form longer filaments for the first 60 min and lose thymidine nucleotides and dTDP-sugar pools at a faster rate for the first 15 min than those of the parent cells, but the dTDP-sugar pool in the parent cells is maintained at high concentration for the first 90 min during thymine starvation. In the recovery of cell growth after re-addition of thymine into the thymine-deprived culture, parent cells recommence growth immediately, but the mutant cells (Ter-15) show a lag-phase for 45 min after which time their growth recommences. The rate of dTTP synthesis for the first 10 to 15 min after re-addition of thymine to thymine-deprived cultures of parent and mutant (Ter-15) cells is three-fold higher than that of thymine nondeprived culture (control), but the rates of dTMP and dTDP-sugar syntheses are the same as those of the control. The total DNA synthesis after re-addition of thymine is equal to that of the control, and the period of thymine starvation other than the number of viable cells during thymine starvation plays an important role. After separation of the filament cells from normal-sized cells by sucrose gradient centrifugation, the initial rate of DNA synthesis of filament cells is three-fold faster than that of normal-sized cells. These results show that the dependency of DNA synthesis upon dTTP concentration is maintained after re-addition of thymine into thymine-deprived culture.
Eur J Biochem 1975 Dec 01
PMID:Studies of intracellular thymidine nucleotides. Thymineless death and the recovery after re-addition of thymine in Escherichia coli K 12. 110 38

An enzyme capable of hydrolyzing the substrate L-alanine p-nitroanilide has been found in the various Escherichia coli strains tested. This enzyme has been called aminoendopeptidase since it shows both activities (see accompanying paper). It is released from the cells by osmotic shock and by lysozyme -- EDTA spheroplasting treatment, and 50% of the total activity is directly detectable with suspensions of intact cells. However, the release by osmotic shock or spheroplasting is not as efficient as it is for alkaline phosphatase. This periplasmic aminoendopeptidase is constitutively produced but the differential rate of synthesis is increased 4-fold when the cell growth is limited by Pi. The occurrence of this 'derepression' is simultaneous with that of alkaline phosphatase. Increasing the concentration of inorganic phosphate in the medium has no effect on the constitutive aminoendopeptidase synthesis. The effect of phosphate starvation is specific since starvation for neither nitrogen nor carbon and energy source are effective in derepressing aminoendopeptidase.
Eur J Biochem 1975 Dec 15
PMID:Evidence for an aminoendopeptidase localized near the cell surface of Escherichia coli. Regulation of synthesis by inorganic phosphate. 110 39


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