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

To evaluate the metabolic consequences of short-term (i.e., less than 24 hours) starvation, glucose and fat metabolism were studied in eight healthy subjects and in eight patients with stable cirrhosis after 16-hour and again after 22-hour starvation by 3-[3H]glucose and [14C]palmitate turnover and by indirect calorimetry. Although patients and controls showed significant increases in free fatty acid concentration (respectively, 48% +/- 12% and 53% +/- 17%) and turnover (55% +/- 14% and 71% +/- 21%) during short-term starvation, the values after 16- and after 22-hour starvation were higher in cirrhosis. Fat oxidation was enhanced in the patients, but did not increase during fasting in contrast to controls (increase 19% +/- 17%, P less than 0.05). Net glucose oxidation was decreased in postabsorptive cirrhotics (P less than 0.05). Although postabsorptive glucose turnover was not different from controls, starvation induced a greater decrease in glucose turnover in the patients (25% +/- 3% vs. 10% +/- 3%, P less than 0.05). This was not reflected in plasma glucose concentrations. In conclusion, the effects of starvation on glucose and fat metabolism are enhanced in cirrhosis; fasting hypoglycemia is prevented by decreased use of glucose. It remains to be established whether these changes are merely explained by defective liver function, per se.
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PMID:Glucose and fat metabolism during short-term starvation in cirrhosis. 199 94

Prolonged fasting (for days or weeks) decreases glucose production and oxidation. The effects of short-term starvation (ie, less than 24 hours) on glucose metabolism are not known. To evaluate this issue, glucose oxidation and glucose turnover were measured after 16-hour and subsequently after 22-hour fasting. Glucose oxidation was calculated by indirect calorimetry in 12 healthy men (age 22 to 44 years); glucose turnover was measured by primed, continuous infusion of 3-3H-glucose in eight of these 12 volunteers. After 16-hour fasting net glucose oxidation was 0.59 +/- 0.17 mg x kg-1 x min-1 and glucose tissue uptake 2.34 +/- 0.12 mg x kg-1 x min-1. No correlation was found between net glucose oxidation and glucose tissue uptake. Prolonging fasting with an additional 6 hours resulted in decreases of respiratory quotient (0.77 +/- 0.01 v 0.72 +/- 0.01) (P less than .005), plasma glucose concentration (4.7 +/- 0.1 v 4.6 +/- 0.1 mmol/L) (P less than .05), glucose tissue uptake (2.10 +/- 0.12 mg x kg-1 x min-1) (P less than .05), net glucose oxidation (0.09 +/- 0.04 mg x kg-1 x min-1) (P less than .005), and plasma insulin concentration (8 +/- 1 v6 +/- 1 mU/L) (P less than .005). Net glucose oxidation expressed as a percentage of glucose tissue uptake decreased from 22% +/- 8% to 2% +/- 1% (P less than .05). There was no net glucose oxidation in seven of 12 controls after 22-hour fasting.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Decreased glucose oxidation during short-term starvation. 211 Jun 8

Brief starvation is accompanied by decreased circulating levels of most amino acids, which has been attributed to an increased splanchnic uptake of amino acids, primarily alanine, for gluconeogenesis. However, quantitative data on splanchnic exchange of amino acids and gluconeogenic precursors is lacking. Consequently, arterial concentrations and splanchnic exchange of whole blood amino acids, ketone bodies, glucose, and gluconeogenic precursors were measured in 16 prolonged fasted (60 to 64 hours) and 15 overnight fasted (12 to 14 hours) healthy, nonobese subjects. After the 60-hour fast net splanchnic glucose production decreased by 41% to 0.31 +/- 0.02 mumol/L (P less than .001), whereas the splanchnic uptake of gluconeogenic precursors increased and could account for the total glucose output. Net splanchnic uptake of taurine, threonine, serine, glycine, lysine, histidine, and arginine rose significantly in response to fasting (P less than .05 to .01) due to increased splanchnic fractional extraction. Although the splanchnic fractional extraction of alanine was augmented by 40% (P less than .001), net splanchnic uptake was not influenced by fasting. Total net splanchnic uptake of amino acids increased by 68%, from 231 +/- 44 mumol/min in the postabsorptive state to 388 +/- 63 mumol/min (mean +/- SEM) (P less than .05) in the 60-hour fasted state. However, only one half of this rise was accounted for by gluconeogenic amino acids.
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PMID:Splanchnic metabolism of amino acids in healthy subjects: effect of 60 hours of fasting. 319 1

Concentrations of free amino acids were measured in human milk and arterial blood from lactating women after an overnight fast or after a controlled breakfast. The concentrations of many free amino acids in milk (except L-tyrosine, L-aspartate, L-asparagine, L-glutamate and L-glutamine) were lower after an overnight fast than after breakfast. Similarly, the arterial concentrations of amino acids were lower except for L-asparagine, L-alanine, L-tyrosine and L-phenylalanine. Net uptake of amino acids by the mammary gland of the lactating rat was significantly lower after starvation for 6 or 24 h than in the fed state because the arteriovenous differences of amino acids and the blood flow were significantly lowered. Starvation produced a significant decrease of 2-amino-[1-14C]isobutyric acid uptake by isolated acini from lactating rat. These results show that short-term starvation decreases the amino acid supply and transport in mammary gland as well as the free amino acid concentration in milk.
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PMID:Effect of fasting on amino acid metabolism by lactating mammary gland: studies in women and rats. 357 66

The value of crystalline amino acids compared with glucose in maintaining functional muscle mass (maximum exercise capacity) in the perioperative period was studied. Twelve surgical patients received 100 g of glucose (Group 1) for 7 to 10 days perioperatively, and 12 (Group 2) received 90 g of crystalline amino acids for a similar period. Maximum exercise capacity, nitrogen balance, and serum albumin were studied. The use of amino acids instead of glucose spared nitrogen. Net nitrogen loss was 64.7 +/- 6.7 g in Group 1 compared with 34.7 +/- 4 g in Group 2 (p less than or equal to 0.001). Exercise capacity decreased 13.8 +/- 4.5 percent in Group 1 and 13.3 +/- 2.9 percent in group 2. The serum albumin level decreased by 0.30 +/- 0.2 g/100 ml in Group 1 compared with 0.34 +/- 0.15 g/100 ml in Group 2. These differences were not significant. Changes in serum albumin were correlated with changes in exercise capacity (r = 0.7, p less than or equal to 0.002), but neither was significantly correlated with nitrogen loss. We concluded that the use of amino acids instead of glucose during moderate periods of semi-starvation associated with moderate trauma will not influence loss of exercise capacity significantly, although some nitrogen will be spared; patients undergoing moderately severe surgical procedures accompanied by moderate periods of semistarvation will lose approximately 14 percent of their exercise capacity; and loss of exercise capacity is not correlated with loss of nitrogen under these conditions but is loosely correlated with changes in serum albumin levels.
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PMID:Relative value of glucose and amino acids in preserving exercise capacity in the postoperative period. 397 97

Adipose tissue is a major site of cholesterol storage. In an attempt to define mechanisms controlling this process, a variety of nutritional and metabolic alterations were employed and their effects on adipose tissue cholesterol levels were determined by direct chemical analysis. When rats were raised on Purina chow, a linear increase in the cholesterol/DNA ratio in relation to animal weight (from 120 g [5-6 wk] to 700 g [2 yr]) occurred. The rate of cholesterol accumulation was related to the dietary cholesterol load. Cholesterol accumulation by adipose tissue also occurred in rats raised on a cholesterol-free diet and reached levels exceeding those observed in animals fed on a diet containing 0.05 or 0.1% (w/w) cholesterol. In rats maintained on semisynthetic diets containing 0 to 5% (w/w) cholesterol, the serum cholesterol concentration was inversely related to the dietary concentration, suggesting that feedback inhibition of cholesterol formation may be an important determinant of serum cholesterol levels in this species. Early dietary alterations affected adipose tissue levels later in life. Net cholesterol mobilization from adipose tissue also occurred after acute starvation. Comparison of obese mice with nonobese littermate controls showed that the size of the adipose cholesterol pool was proportional to the degree of adipocity because the amount of cholesterol stored per unit glyceride mass was identical. Adipose tissue cholesterol was not affected by animal sex. Thus, adipose tissue cholesterol levels were dependent on animal age, dietary cholesterol load, early nutritional deprivations, and the size of the adipose organ itself.
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PMID:Regulation of cholesterol storage in adipose tissue. 441 22

Changes are reported in total cellular organic carbon, nucleic acids, proteins, carbohydrates, lipids and chlorophylls during the course of silicon-starvation synchrony of Navicula pelliculosa. All constituents increased at the same rate, relative to cell number, for 30 hours of exponential growth during which silicon was depleted from the medium. Increase in cell number then stopped, but net synthesis of most components continued for a further 5 to 7 hours before ceasing. Deoxyribonucleic acids and lipids accumulated throughout the 14 hour silicon-starvation period. When silicon was resupplied, lipid synthesis ceased and organic carbon and carbohydrates decreased slightly. Net synthesis remained low during the 4 hour silicon uptake period but was resumed at higher rates as cell number began to rise. In cultures transferred to the dark 1 hour prior to readdition of silicon, total carbon, carbohydrates, and lipids decreased markedly during silicon uptake and cell separation. This was due in part to conversion of protein which maintained the protein level of the dark cells close to that of cells kept in the light. Mechanisms by which silicon starvation and reintroduction of silicon might affect rates of cellular synthesis are discussed.
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PMID:Studies on the biochemistry and fine structure of silica shell formation in diatoms. Chemical composition of Navicula pelliculosa during silicon-starvation synchrony. 608 Aug 72

During prolonged starvation, brain energy requirements are covered in part by the metabolism of ketone bodies. It is unknown whether short-term starvation of a few days' duration may lead to reduced brain glucose metabolism due to the change toward ketone body consumption. In the present study we measured the cerebral metabolism of glucose and ketone bodies in nine healthy volunteers before and after 3.5 days of starvation. Regional glucose metabolism was measured by dynamic positron emission tomography using [18F]2-fluoro-2-deoxy-D-glucose. The mean value of K1* in gray and white matter increased by 12% (p < 0.05), whereas k2* and k3* were unchanged compared with control values. Regional glucose metabolism in cortical gray matter was reduced by 26% from 0.294 +/- 0.054 to 0.217 +/- 0.040 mumol g-1 min-1 (p < 0.001). White matter glucose metabolism decreased by 27% (p < 0.02). The decrease was uniform in gray and white matter with regional decreases ranging from 24 to 30%. A determination using Fick's principle confirmed the reduction in glucose metabolism yielding a decrease of 24% from 0.307 +/- 0.050 to 0.233 +/- 0.073 mumol g-1 min-1 (p < 0.05), whereas CBF did not change (0.57 +/- 0.07 vs. 0.57 +/- 0.06 ml g-1 min-1). The global net uptake of beta-hydroxybutyrate increased 13-fold from 0.012 +/- 0.024 to 0.155 +/- 0.140 mumol g-1 min-1 (p < 0.05). Net uptake of acetoacetate and net efflux of lactate and pyruvate did not change significantly during starvation. The present study shows that the human brain adapts to the changes in energy supply as early as 3 days following initiation of starvation, at which time ketone bodies account for approximately one-fourth of the cerebral energy requirements.
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PMID:Brain metabolism during short-term starvation in humans. 826 48

We studied changes in lipid metabolism in adipose tissue in 24 healthy adults during early starvation (14-20 h) by cannulating the venous drainage of the subcutaneous adipose tissue of the anterior abdominal wall. Net nonesterified fatty acid (NEFA) efflux from adipose tissue increased steadily from 1,790 +/- 300 to 2,360 +/- 290 nmol.100 g-1.min-1 (P = 0.03), due to increasing transcapillary efflux of NEFA (release from adipocytes; P < 0.01). The reesterification rate after an overnight fast was close to zero; thus, reduction in the rate of reesterification played no part in the increased transcapillary efflux of NEFA. One-quarter of the net efflux of NEFA after an overnight fast arose from the action of lipoprotein lipase (LPL), although this relative contribution decreased during the study (P < 0.02). The increased transcapillary efflux of NEFA reflected a significant increase in the rate of action of hormone-sensitive lipase (HSL; P = 0.03). There was a strong relationship between mean arterial NEFA concentration and net NEFA release from adipose tissue (P < 0.001), implying that the particular depot studied reflects the behavior of adipose tissue as a whole. Thus the increasing efflux of NEFA from adipose tissue observed during early starvation is due to an increased rate of action of HSL, which may in turn be regulated by a fall in the plasma insulin concentration.
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PMID:Regulation of lipid metabolism in adipose tissue during early starvation. 884 49

In fed, anesthetized rats, microdialysis demonstrated a net release of glycerol, glutamine, serine, tyrosine, and taurine and a net uptake of glutamate, aspartate, glycine, and arginine across the inguinal adipose depot. However, the results also indicated excessive proteolysis associated with implantation of the microdialysis probe, and a novel arteriovenous difference technique was developed. Arteriovenous difference across the inguinal fat pat demonstrated a net uptake of glucose and a net release of lactate and glycerol. Starvation (48 h) resulted in higher rates of glycerol and lactate release with lower rates of glucose uptake. A net uptake of triacylglycerol was seen in starved-refed animals. Net glutamine, tyrosine, and taurine release was seen in fed and starved animals, but in starved-refed animals taurine and serine were the only amino acids showing significant release. No significant net uptake or release of ammonia, pyruvate, or alanine was observed. These experiments confirm that adipose tissue is a site of glutamine synthesis and suggest that the principal substrates are derived from intracellular proteolysis. The results also demonstrate the viability of an arteriovenous difference technique for the study of adipose tissue in the rat.
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PMID:Rat adipose tissue amino acid metabolism in vivo as assessed by microdialysis and arteriovenous techniques. 931 53


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