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 many causes of clinical magnesium deficiency can be placed into 2 categories: diminished intake of magnesium, and enhanced losses of magnesium, either through the gastrointestinal tract or through the kidneys. Examples of the first category include alcoholism, starvation, anorexia due to neoplastic disease and/or chemotherapy. Examples of the second category include severe diarrhoeal states, gastrointestinal fistulae, malabsorption, diuretic therapy and gentamicin therapy. Estimates of the prevalence of clinical hypomagnesaemia range from 6 to 11% in hospitalised patients. Serum predictors of associated clinical magnesium depletion include hypokalaemia (42%), hyponatraemia (23%), hypophosphataemia (22%) and hypocalcaemia (20%). Experimental and clinical observations strongly support the view that magnesium and potassium are closely linked at the cellular level. Magnesium has been demonstrated to be important in cell energetics (Mg++-activated ATPase), in maintenance of the integrity of cell membranes, retardation of cell loss of potassium, as well as enhancing repletion of cell potassium. While translation of these experimental observations into clinical terms encompasses a wide spectrum of illnesses, there is special relevance in considering the role of magnesium in repletion and maintenance of cell potassium in 2 clinical instances: (a) patients treated with digitalis and diuretics; and (b) hypertensive patients. In these types of patients not only potassium but also magnesium should be administered together to avoid the problem of cell potassium depletion and refractory potassium repletion associated with coexisting and uncorrected magnesium depletion.
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PMID:Magnesium deficiency. Causes and clinical implications. 649 96

Glutamate dehydrogenase activity in the liver of the rainbow trout increases when the animals are starved for four weeks. Glutamate dehydrogenase, alanine aminotransferase and aspartate aminotransferase activity in the kidney of rainbow trout kept in sea water (20% S) is significantly higher than in the kidney of rainbow trout kept in fresh water. Gill Na/K-ATPase activity in the rainbow trout is reduced significantly (44%) by starvation for four weeks. Most of the free amino acids investigated in the white muscle of the rainbow trout were present in significantly higher concentrations in animals fed in sea water than in animals fed in fresh water. The concentrations of these amino acids are even higher in the muscle of starved animals held in sea water than in fed animals held in sea water.
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PMID:Influence of nutrition on biochemical sea water adaptation of the rainbow trout (Salmo gairdneri richardson). 661 64

Male inbred Fischer rats were fed a diet containing 5 p.p.m. aflatoxin for 1, 3, 4 1/2 and 6 weeks at which times groups were killed for histological and histochemical study. Aflatoxin produced a scattered individual cell necrosis of parenchymal cells by 1 week. At 3 weeks small basophilic proliferative foci were seen which increased in size and abundance to 6 weeks. These foci showed starvation-resistant glycogen, variable depletion of glucose-6-phosphatase, succinic dehydrogenase, aniline hydrogenase, membrane ATPase and acid phosphatase. At 6 weeks the foci showed the presence of gamma glutamyl transpeptidase and glucose-6-phosphate dehydrogenase. The basophilic foci were not preceded by other focal histological and histochemical change. The basophilic proliferative lesions are observed when an irreversible change has been induced in the liver. The role of such lesions in the histogenesis of hepatocellular carcinoma is discussed.
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PMID:Histochemical studies on the early proliferative lesion induced in the rat liver by aflatoxin. 724 Dec 69

D. discoideum amoebae were found to phosphorylate plasma membrane proteins when intact cells were incubated with either [gamma-32P]ATP or [32P]phosphate. In the first case, the incorporation was largely a consequence of the hydrolysis of [gamma-32P]ATP, cellular uptake of the generated [32P]phosphate and its subsequent incorporation into ATP. When the contribution of this process to the phosphorylating activity of intact cells was eliminated, an ecto-protein kinase (ATP: protein phosphotransferase, EC 2.7.1.37) activity could be demonstrated. As amoebae progressed through their aggregation program, they showed a decreased ability to phosphorylate their plasma membrane when incubated with [gamma-32 P]ATP or [32P]phosphate. Analysis of ATPase activity, permeability properties and the pattern of proteins phosphorylated by intact cells and isolated plasma membranes lead to the following conclusions: the lower levels of phosphorylation observed with starved cells reflected an altered uptake of [32P]phosphate by these cells rather than a significant change in the plasma membrane protein kinase activity. Neither the substrates nor the activity of the ecto-protein kinase was dramatically altered during starvation.
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PMID:A protein kinase of the plasma membrane of Dictyostelium discoideum. 731 41

The composition of phospholipids, sphingolipids, and sterols in the plasma membrane has a strong influence on the activity of the proteins associated or embedded in the lipid bilayer. Since most lipid-synthesizing enzymes in Saccharomyces cerevisiae are located in intracellular organelles, an extensive flux of lipids from these organelles to the plasma membrane is required. Although the pathway of protein traffic to the plasma membrane is similar to that of most of the lipids, the bulk flow of lipids is separate from vesicle-mediated protein transport. Recent advances in the analysis of membrane budding and membrane fusion indicate that the mechanisms of protein transport from the endoplasmic reticulum to the Golgi and from the Golgi to plasma membrane are similar. The majority of plasma membrane proteins transport solutes across the membrane. A number of ATP-dependent export systems have been detected that couple the hydrolysis of ATP to transport of molecules out of the cell. The hydrolysis of ATP by the plasma membrane H(+)-ATPase generates a proton motive force which is used to drive secondary transport processes. In S. cerevisiae, many substrates are transported by more than one system. Transport of monosaccharide is catalyzed by uniport systems, while transport of disaccharides, amino acids, and nucleosides is mediated by proton symport systems. Transport activity can be regulated at the level of transcription, e.g., induction and (catabolite) repression, but transport proteins can also be affected posttranslationally by a process termed catabolite inactivation. Catabolite inactivation is triggered by the addition of fermentable sugars, intracellular acidification, stress conditions, and/or nitrogen starvation. Phosphorylation and/or ubiquitination of the transport proteins has been proposed as an initial step in the controlled inactivation and degradation of the target enzyme. The use of artificial membranes, like secretory vesicles and plasma membranes fused with proteoliposomes, as model systems for studies on the mechanism and regulation of transport is evaluated.
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PMID:The plasma membrane of Saccharomyces cerevisiae: structure, function, and biogenesis. 760 12

A membrane fraction enriched with plasma membranes was isolated from rat ileal brush-border cells before and after five-day starvation of the animals. Cholesterol/phospholipid ratio of the standard cell membranes decreased highly significantly (0.42 to 0.18), as did the microviscosity of the membranes determined by polarization of fluorescence (0.187 to 0.142). Concomitantly, the specific activity of Na,K-ATPase in the basolateral membranes significantly increased (59 to 83 mumol ATP hydrolyzed per mg protein per min).
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PMID:Modifications of functional and physico-chemical properties of rat ileal plasma membranes. 762 34

Conventional myosin has two different light chains bound to the neck region of the molecule. It has been suggested that the light chains contribute to myosin function by providing structural support to the neck region, therefore amplifying the conformational changes in the head following ATP hydrolysis (Rayment et al., 1993). The regulatory light chain is also believed to be important in regulating the actin-activated ATPase and myosin motor function as assayed by an in vitro motility assay (Griffith et al., 1987). Despite extensive in vitro biochemical study, little is known regarding RMLC function and its regulatory role in vivo. To better understand the importance and contribution of RMLC in vivo, we engineered Dictyostelium cell lines with a disrupted RMLC gene. Homologous recombination between the introduced gene disruption vector and the chromosomal RMLC locus (mlcR) resulted in disruption of the RMLC-coding region, leading to cells devoid of both the RMLC transcript and the 18-kD RMLC polypeptide. RMLC-deficient cells failed to divide in suspension, becoming large and multinucleate, and could not complete development following starvation. These results, similar to those from myosin heavy chain mutants (DeLozanne et al., 1987; Manstein et al., 1989), suggest the RMLC subunit is required for normal cytokinesis and cell motility. In contrast to the myosin heavy chain mutants, however, the mlcR cells are able to cap cell surface receptors following concanavilin A treatment. By immunofluorescence microscopy, RMLC null cells exhibited myosin localization patterns different from that of wild-type cells. The myosin localization in RMLC null cells also varied depending upon whether the cells were cultured in suspension or on a solid substrate. In vitro, purified RMLC- myosin assembled to form thick filaments comparable to wild-type myosin, but the filaments then exhibit abnormal disassembly properties. These results indicate that in vivo RMLC is necessary for myosin function.
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PMID:Targeted disruption of the Dictyostelium RMLC gene produces cells defective in cytokinesis and development. 780 58

Effects of starvation and glucose preincubation on membrane potential, ATPase-mediated acidification and glutamic acid transport were studied in yeast species Saccharomyces cerevisiae, Schizosaccharomyces pombe, Dipodascus magnusii, Lodderomyces elongisporus and Rhodotorula gracilis. The membrane potential was highest after preincubation with glucose in all species but L. elongisporus and R. gracilis. In all cases the membranes were depolarized in the presence of 20 mmol/L KCl and hyperpolarized with 50 mumol/L diethylstilbestrol (DES). The extracellular acidification caused by addition of glucose was highest after preincubation with glucose in all cases except in R. gracilis where there was none. In all cases except in R. gracilis addition of KCl caused a marked increase in the acidification rate. Addition of DES with glucose caused a large decrease in rate in S. cerevisiae but had much less effect on the other species. Transport of glutamic acid was clearly increased after pretreatment with glucose in S. cerevisiae, S. pombe and D. magnusii (mainly due to enhanced synthesis of the carrier) but actually decreased in R. gracilis and L. elongisporus. Addition of DES had an inhibitory effect in all species but much more pronounced in S. cerevisiae and S. pombe than in others. In general, both the acidification and the transport of glutamate were enhanced after preincubation with glucose but much more so in the semianaerobic species, such as S. cerevisiae, than in the strict aerobes (R. gracilis) where the effect was occasionally negative. There was no relationship between the ATPase-mediated acidification and the membrane potential.
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PMID:Effects of the physiological state of five yeast species on H(+)-ATPase-related processes. 790 55

Bovine corneal endothelial cells showed a strong migratory response to specific simple sugars (D-glucose and sucrose, but not L-glucose, sorbitol, lactose, or D-galactose) at concentrations above 10 mM. Checkerboard analysis of the migratory responses in modified Boyden chambers indicated both chemotactic and chemokinetic effects. Serum starvation of the cultures increased the chemotaxis towards D-glucose and 2-deoxy-D-glucose, but not towards sucrose. Migration to sucrose and glucose was inhibited by chelation of extracellular calcium or by inhibition of Na+, K+ ATPase with ouabain. To date, this migratory response has been found only in corneal endothelial cells. Neither human melanoma cells, human breast carcinoma cells, bovine aortic endothelial cells, nor bovine microvascular endothelial cells migrated towards simple sugars, although all cell types migrated toward fibronectin in chemotaxis assays. After 16-19 passages in culture, bovine corneal endothelial cells retained their ability to migrate towards fibronectin, but lost their ability to migrate towards sugars. This loss of migratory response was accompanied by a sevenfold decrease in Na+, K+ ATPase activity. Although loss of Na+, K+ ATPase activity accompanied the loss of migratory response, pretreatment of cell cultures with 25 mM glucose did not stimulate, but rather lowered Na+, K+ ATPase activity in low or high passage cultures.
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PMID:Specific simple sugars promote chemotaxis and chemokinesis of corneal endothelial cells. 822 67

PMA1 expression, plasma membrane H(+)-ATPase enzyme kinetics, and the distribution of the ATPase have been studied in carbon-starved Candida albicans induced with glucose for yeast growth at pH 4.5 and for germ tube formation at pH 6.7. PMA1 expression parallels expression of the constitutive ADE2 gene, increasing up to sixfold during yeast growth and twofold during germ tube formation. Starved cells contain about half the concentration of plasma membrane ATPase of growing cells. The amount of plasma membrane ATPase is normalized prior to either budding or germ tube emergence by the insertion of additional ATPase molecules, while ATPase antigen appears uniformly distributed over the entire plasma membrane surface during both growth phases. Glucose addition rapidly activates the ATPase twofold regardless of the pH of induction. The turnover of substrate molecules per second by the enzyme in membranes from budding cells quickly declines, but the enzyme from germ tube-forming cells maintains its turnover of substrate molecules per second and a higher affinity for Mg-ATP. The plasma membrane ATPase of C. albicans is therefore regulated at several levels; by glucose metabolism/starvation-related factors acting on gene expression, by signals generated through glucose metabolism/starvation which are thought to covalently modify the carboxyl-terminal domain of the enzyme, and possibly by additional signals which may be specific to germ tube formation. The extended period of intracellular alkalinization associated with germ tube formation may result from regulation of proton-pumping ATPase activity coupled with higher ratios of cell surface to effective cytosolic volume.
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PMID:The Candida albicans plasma membrane and H(+)-ATPase during yeast growth and germ tube formation. 836 41


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