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PubMed1965

REGULATION OF ASCORBIC ACID AND OF XYLULOSE SYNTHESIS IN LIVER EXTRACTS. THE EFFECT OF STARVATION IN VARIOUS ANIMALS.

1. The effect of starvation on the synthesis of ascorbic acid and of xylulose from glucuronolactone and from gulonate has been studied with liver extracts from cats, rabbits, hamsters, mice and guinea pigs. 2. The synthesis of ascorbic acid from glucuronolactone is decreased in all species except cats, and that from gulonate is decreased in hamsters and mice only. 3. The synthesis of xylulose from glucuronolactone was decreased in all species except cats and mice, whereas from gulonate it was enhanced in all the species examined.

Animals↗
PubMed1975

Starvation and seizures. Observation on the electroconvulsive threshold and cerebral metabolism of the starved adult rat.

Acute starvation of adult rats resulted in a rise in the electroconvulsive threshold at 48 hours (P less than .10) and at 72 hours (P less than .01), but not at 24 hours. Biochemical correlates included (1) ketonemia and mild hypoglycemia in the blood; (2) a significant rise in the brain cytoplasmic phosphorylation potential and in the energy charge potential; (3) a shift in the brain cytoplasmic oxidation-reduction potential to a more oxidized state; (4) probable partial inhibitions in brain phosphofructokinase and pyruvate dehydrogenase; and (5) relatively small increases in brain sodium (4.1%), potassium (2.4%), and chloride (4.3%). No major differences were seen in brain water content or adenosine triphosphatase activity. The observed cerebral biochemical alterations are believed to be the consequence of increased ketone body utilization, although the precise relationship to the alteration in the electroconvulsive threshold remains unclear.

Adenosine Triphosphatases↗
PubMed1997

Beyond body image: the integration of feminist and transcultural theories in the understanding of self starvation.

OBJECTIVE: The present study represents an intersection between cross-cultural theorizing and teminist scholarship. It is an attempt to provoke as well as augment prevailing biomedical models that esteem fear of fatness as the primary motivation for voluntary starvation in anorexic women. METHOD: Recent studies of eating disturbance in both Eastern and Western societies are invoked to demonstrate the ways in which women straddling two worlds, be it generational, work-family, cultural or traditional and modern, may employ food denial as an instrumental means of negotiating the transition, disconnection, and oppression that they uniformly endure. RESULTS: A feminist/transcultural interpretation of the literature suggests that by construing anorexia nervosa as a body image disorder or Western culture-bound syndrome, extant models miss the broader contexts and varied meanings of food refusal. DISCUSSION: The implications of cross-disciplinary perspectives for theory building and treatment are discussed, acknowledging not only the gendered nature of eating disorders but their embodiment of power differentials as well.

Anorexia Nervosa↗
PubMed1979

Effects of bicuculline-induced seizures on cerebral metabolism and circulation of rats rendered hypoglycemic by starvation.

To evaluate the effects of substrate deficiency on cerebral function, metabolism, and blood flow during seizures, rats were injected intravenously with bicuculline (1.2 mg.kg-1) following a 24-hour period of starvation. During the course of seizures, blood glucose concentrations fell, and when they were reduced to below about 3 mumol.gm-1, cerebral function, metabolism, and blood flow altered. Changes in function involved the transition of an electroencephalographic pattern of bursts and suppression into one of frequent or sparse single spikes. Oxygen consumption, which initially increased at least twofold, fell toward normal or subnormal values in the single-spike period. Cortical blood flow was markedly reduced, and there was an attenuated response to carbon dioxide administration. Simultaneously, a small but clear fall was detected in the cerebral phosphorylation potential, and concentrations of glycolytic metabolites (including lactate) and citric acid cycle intermediates were reduced. Changes in amino acids and ammonia were somewhat similar to those observed in insulin-induced hypoglycemia, but since the amino acid pool did not fall, the experiments failed to give evidence that amino acids serve as oxidative substrates. The perturbation of cerebral energy state (and of levels of carbohydrate substrates and amino acids) was reversed by glucose administration; but since neither this procedure nor additional bicuculline injections could cause resumption of continuous seizure activity, the results suggest that cellular substrate depletion may have given rise to a sustained disturbance of synaptic transmission.

Animals↗
PubMedDate not supplied

Effect of starvation on insulin production and insulin binding in Tetrahymena.

Tetrahymena pyriformis GL was starved for 24 h and then the immunologically demonstrable insulin content and FITC-insulin binding were measured by flow cytometry and localization was studied by confocal microscopy. The amount of endogeneous insulin as well as FITC insulin binding, was highly significantly elevated. Glucose feeding for 30 min abolished the elevation of FITC-insulin binding. In starved cells, insulin-binding sites disappeared from the surface and FITC-insulin was bound inside the cells, within large food vacuoles. Endogeneous insulin was dispersed in the cytoplasm both in the control and starved cells and food vacuoles did not contain it. The results call attention to the stimulatory effect of starvation on insulin production in Tetrahymena, in parallel with the internal storage of insulin receptors, which points to an autocrine mechanism.

Animals↗
PubMed1981

Heightened arousal in the 2-week-old rat: the importance of starvation.

The 2-week-old rat has frequently been reported to be hyperactive; however, the causes of this are disputed. In 3 experiments, with split-litter designs, the following possibilities were eliminated as causative factors: (a) body temperature; (b) nest seeking; and (c) maturation of peripheral sensory, motor, and endocrine systems. In contrast, the isolated 2-week-old rat, in a novel environment, was shown to be very reactive to hunger, however mild. Further, this was true whether the hunger was self-generated during a forced switch in diet or external origin due to food deprivation. These data are consistent with and supportive of the hypothesis that the 2-week-old rat does not have functionally-mature forebrain inhibitory structures with which to modulate arousal. Thus, even a mild arousal stimulus results in extreme hyperactivity. Further, these results, together with previously published results, suggest that the concurrence of isolation, starvation, and novelty of environment are necessary, but none of these alone is sufficient, for the 2-week-old rat to become hyperactive.

Age Factors↗
PubMed1995

Paraquat resistance and starvation conditions in the selection of longevity extremes in Drosophila melanogaster populations previously selected for long and short developmental period.

This paper analyzes the interaction between resistance to free radicals, development under starvation conditions, sex, and its consequences to the lifespan of Drosophila melanogaster populations selected for developmental time and longevity. Our data suggest that the interaction between these physiological and environmental parameters is modulated largely by the pre-imaginal developmental time, since the response to selection for longevity extremes depends strongly on the previous selection for developmental time extremes.

Animals↗
PubMed1976

[Lysosomal enzymes in starvation after regimen of single or all-day feeding].

The authors studied in rats the effect of starving from 24 to 96 hours after a regimen of single or all-day feeding. They determined in liver homogenate the total activities of beta-N-acetyl glucosaminidase, acid phosphatase and beta-glucuronidase as well as the free activities of the two first-mentioned enzymes. The activity of beta-N-acetyl glucosaminidase was also determined in the blood. It was found that the total activity of beta-N-acetyl glucosaminidase in the liver homogenate increased with the length of starvation. The free and serum activities of the enzymes under investigation showed similar changes. These increases were more marked in rats subjected to a single-feeding regimen before starving. These changes are explained as an expression of the active participation of the lysosomes and their enzymes in the transition to endogenous feeding. The lysosomal membrane was more sensitive in starving animals which had been subjected to a single-feeding regimen.

Acetylglucosaminidase↗
PubMed1990

Effects of starvation and neuroactive drugs on feeding in Caenorhabditis elegans.

Caenorhabditis elegans concentrates its food, bacteria, by pharyngeal pumping. The rate of pumping is affected by the presence of bacteria. Using a new assay that allows measurement of pumping rate in a population of worms suspended in liquid by measuring their uptake of microscopic iron particles, we have confirmed and quantitated this effect. Furthermore, we demonstrated that starvation stimulates pumping. Worms that had been deprived of bacteria for more than 4 hours pumped in the absence of bacteria under conditions in which well-fed worms did not. Furthermore, starved worms responded to lower amounts of bacteria than did fed worms. The assay was also useful for measuring effects of drugs on pumping. Of about 30 chemicals screened, 5 had clear effects. The neurotransmitter serotonin and the serotonin uptake inhibitor imipramine stimulated pumping, while the serotonin antagonist gramine inhibits. Imipramine stimulation is greatly decreased in cat-1 and cat-4 mutants, which have low levels of serotonin. Muscimol, an agonist for the neurotransmitter GABA, and ivermectin, whose site of action may also be the GABA receptor, both inhibit pumping. Qualitative observations suggested a role for acetylcholine in the regulation of pumping.

Acetylcholine↗
PubMed1984

Alterations of endocrine pancreas B cells in a sahelian reptile (Varanus exanthematicus) during starvation.

During the long starvation period (November to June) of the lizard (Varanus exanthematicus), pancreatic B cells undergo profound modification. The degeneration of beta granules observed in electron microscopy appears correlated with the diminution of the immunoreactive insulin-like content of the pancreas. The analogy between the phenomena observed here and those reported in animals treated with alloxan is discussed.

Animals↗
PubMed2004

Proteomic response to amino acid starvation in Candida albicans and Saccharomyces cerevisiae.

Saccharomyces cerevisiae activates general amino acid control (GCN) in response to amino acid starvation. Some aspects of this response are known to be conserved in other fungi including Candida albicans, the major systemic fungal pathogen of humans. Here, we describe a proteomic comparison of the GCN responses in S. cerevisiae and C. albicans. We have used high-resolution two-dimensional (2-D) gel electrophoresis and peptide mass fingerprinting to develop a 2-D protein map of C. albicans. A total of 391 protein spots, representing 316 open reading frames, were identified. Fifty-five C. albicans and 65 S. cerevisiae proteins were identified that responded reproducibly to 3-aminotriazole (3AT) in a Gcn4p-dependent fashion. The changes in the S. cerevisiae proteome correlated with the response in the S. cerevisiae transcript profile to 3AT treatment (rank correlation coefficient = 0.59; Natarajan et al., Molec. Cell. Biol. 2001, 21, 4347-4368). Significant aspects of the GCN response were conserved in C. albicans and S. cerevisiae. In both fungi, amino acid biosynthetic enzymes on multiple metabolic pathways were induced by 3AT in a Gcn4p-dependent fashion. Carbon metabolism functions were also induced. However, subtle differences were observed between these fungi. For example, purine biosynthetic enzymes were induced in S. cerevisiae, but were not significantly induced in C. albicans. These differences presumably reflect the contrasting niches of these relatively benign and pathogenic yeasts, respectively.

Amino Acids↗
PubMed1993

Regulation of mitochondrial 3-hydroxy-3-methylglutaryl-coenzyme A synthase protein by starvation, fat feeding, and diabetes.

We have determined the levels of mitochondrial 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) synthase under different metabolic situations to examine its potential role as a regulatory protein in the ketogenic pathway. We used specific antibodies directed against a peptide of the amino acid sequence of the protein as deduced from the cDNA sequence. The amount of mitochondrial HMG-CoA synthase protein rapidly increased in response to cyclic AMP, dexamethasone, starvation, fat feeding, and diabetes, whereas it was decreased by insulin and refeeding. Insulin was also able to counteract the increase in mitochondrial HMG-CoA synthase levels observed under the diabetic condition. Furthermore, the finding that quantitative changes in HMG-CoA synthase protein were less marked than those in the corresponding mRNA in starved and diabetic rats suggests either translational control or increased degradation of either mRNA or protein. All these results indicate that mitochondrial HMG-CoA synthase is a regulatory element in the ketogenic process.

Animals↗
PubMed1994

The eIF-2 alpha kinases: regulators of protein synthesis in starvation and stress.

Phosphorylation of translation initiation factor 2 alpha is a highly conserved mechanism for down-regulating protein synthesis in response to starvation or stress. The yeast eIF-2 alpha kinase GCN2 is stimulated by deprivation for amino acids or purines. In addition to inhibiting general protein synthesis, GCN2 specifically stimulates translation of GCN4, a transcriptional activator of amino acid biosynthetic genes. HRI is an eIF-2 alpha kinase that is activated in rabbit reticulocytes by heme-deprivation and stress conditions that elicit the heat-shock response. The eIF-2 alpha kinase DAI is activated by double-stranded RNA during viral infections and is an important component of the interferon response. DAI has also been implicated as a tumor suppressor. These protein kinases provide an important means of coupling the rate of protein synthesis and cell division to environmental conditions.

Animals↗
PubMed1975

Oogenesis in Xenopus laevis (Daudin). IV. Effects of gonadotropin, estrogen and starvation on endocytosis in developing oocytes.

This study was designed to explore the relationship of estrogen, human chorionic gonadotropin (HCG), and food availability to endocytosis in developing oocytes. When estrogen alone is administered to an animal, large amounts of vitellogenin are synthesized by the liver and secreted into the circulatory system, where it accumulates. Under these conditions there is no evidence of endocytosis at the surface of the oocytes. Other studies have shown that following HCG injection into estrogen-treated animals, vitellogenin is removed from the circulation and the oocyte surface is highly contoured and displays endocytotic activity. Food deprivation has much the same effect on oocyte endocytosis as does estrogen. When animals are given HCG and subsequently starved for 20 days, developing oocytes show little endocytotic activity. We conclude that HCG acts to promote or stimulate endocytosis in developing oocytes while estrogen and/or starvation inhibits this process.

Animals↗
PubMed1977

Ultrastructural changes in midgut cells of female Aedes aegypti L. (Insecta, Diptera) after starvation or sugar diet.

The ultrastructure of the epithelial cells in the posterior part of the midgut in female Aedes aegypti was partly changed after starvation periods of 5 or 8 days. Most obvious is a drastic reduction of the amount of rough endoplasmic reticulum (rer), which is responsible for the synthesis of enzymes for blood digestion. A similar influence on rer membranes is to be observed in mosquitoes fed on sucrose solution only, without additional blood meals.

Aedes↗
PubMed1990

Comparative glucose tolerance studies in the freshwater snail Biomphalaria glabrata: influence of starvation and infection with the trematode Schistosoma mansoni.

The dynamic reactions of B. glabrata on intravasal loads of 20-1000 micrograms glucose.g live fresh wt-1 were studied in standard fed snails (SFS). Starved snails (SS) and snails infected with S. mansoni (IS) were given 100-500 micrograms glucose.g fresh live wt-1. Mean hemolymph glucose level was 12.1 mg.100 ml-1 in SFS. It was not significantly lower in SS (10.7 mg.100 ml-1), but significantly reduced in IS (8.5 mg.100 ml-1). Since hemolymph volumes were significantly increased in SS, the amount of circulating glucose (pool) did not change (75 micrograms.g body weight-1) compared to SFS (62 micrograms.g-1). It was, however, reduced to 41 micrograms.g-1 in IS. In SFS the circulating glucose pool had to be doubled to induce significantly elimination of the injected glucose. Tripled pools were eliminated with half-times of 45 min, whereas lower and higher glucose loads were eliminated significantly slower (half-times: 80-105 min). Glucose tolerance of SS was reduced: half-times were doubled, and metabolization of injected glucose was reduced. Since tissue fresh weights were lowered by 40%, absolute incorporation of 14C from labeled glucose was lowered, but specific incorporation (per mg) was higher than in SFS and IS. Glucose tolerance of IS was increased: metabolic clearance rates rose by 70% and half-times were shortened by 30%, though absolute and specific rates of 14C incorporation were lowered. However, IS lost 25% of the label to the water, whereas SFS lost 12% and SS only lost 8%. Using the antimetabolite 2-deoxyglucose, 80% of the losses proved to be glucose in IS, and 50% in SFS. The present results suggest the existence of a glucostatic regulation in B. glabrata with lower sensitivity and capacity than in mammals. As to glucose tolerance, the often reported parallelism in metabolic shifts induced by starvation and parasitic infection was not confirmed.

Animals↗
PubMed1992

Effects of starvation on valine and alanine transport across the intestinal mucosal border in sea bass, Dicentrarchus labrax.

Kinetics of intestinal transport of L-alanine and L-valine (substrates of the A-system and the L-system, respectively, in mammals) across the brush-border membrane in sea bass, Dicentrarchus labrax, were studied on intact mucosa using a short-term uptake technique. When fish were starved for 4-8 weeks, total influx (mucosa-to-cell) of valine fell owing to disappearance or modification of the diffusion component. The maximum influx rate of saturable component increased but its affinity (reflected by the Michaelis constant) decreased. Alanine transport by Na(+)-dependent and diffusion pathways was unchanged after starvation. Fasting also induced an almost 20% decrease in the length of intestinal microvilli.

Alanine↗
PubMed1980

Carbohydrate reserves and hemolymph sugars of the African giant snail, Achatina fulica in relation to parasitic infection and starvation.

In the snail, Achatina fulica, parasitized by the rat lungworm Angiostrongylus cantonensis, levels of carbohydrate in hemolymph and digestive glands were determined. The normal level of hemolymph glucose of 11.7 mg% dropped to 4.25 mg% in the infected snails, a significant difference after only one week of infection. The level of total reducing sugar in the hemolymph also decreased significantly (12.3 mg% to 3.6 mg%) in this period. Later on, the snails were capable of adapting themselves to the parasitic infection and the concentration of hemolymph sugars returned to the normal range. Starvation caused a decrease in the carbohydrate reserves of the digestive gland only when the starved snails had been previously infected.

Angiostrongylus↗