Effect of enzyme treatment of nutrient uptake by chick embryo fibroblasts.
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Aminoisobutyric Acids↗
Biomedical subjects
L Cynober
Publications and source records attributed to L Cynober.
Plasma amino acid levels in the first few days after burn injury and their predictive value.
Plasma amino acid concentrations were studied in 27 burn subjects on the day of injury and on day 4, as a function of the burn surface area and the outcome. On the day of injury, compared to normal subjects, plasma amino acid levels were generally higher in the most severely burned patients (significantly for ALA, GLY, HYP and PHE) and in nonsurvivors (significantly for ALA, PHE, GLY, PRO and ORN). In burn patients all initial values were higher in nonsurvivors than in survivors; for ALA, GLY, and LEU, the difference was significant. Between the day of injury and day 4, different variations were noticed depending on the amino acid in question and the outcome. On day 4, plasma amino acid levels were lower in nonsurvivors, significantly for GLU + GLN, THR, SER, PRO, ASP + ASN, LEU, ILEU and VAL. Our data suggest that plasma amino acid determination could be used as an accurate element of prognosis after burn injury.
Adult↗
[Measurement of plasma and urinary amino acids with gas chromatography in healthy subjects. Variations as a function of age and sex].
Using gas chromatography, we measured the concentrations of amino acids in a group of 80 selected subjects: we present the plasma values which we obtained, as well as those of other authors. Various comparisons were made, according to the age and/or sex of the subjects. We found that the plasma levels of valine, leucine, isoleucine and proline in patients of any age, the levels of hydroxyproline and phenylalanine in subjects over the age of 45 and the levels of ornithine in subjects under the age of 45, are higher in men, while the level of threonine is higher in women under the age of 45 than in men of the same age. These sex differences are significant. Valine, leucine, isoleucine, hydroxyproline, phenylalanine and ornithine are significantly higher in the plasma of elderly men, while plasma ornithine is higher and plasma threonine is lower in elderly women than in young women. We also determined the normal values of urinary amino acids and were unable to demonstrate any differences in terms of age or sex. We defined four groups of amino acids, according to their clearance values. However, these groups do not correspond to those defined by the existence of renal tubular transport systems common to certain amino acids.
Adolescent↗
[Blood cortisol level variations in burn patients and their relation to variations in plasma amino acids. Biochemical study of 19 subjects].
Cortisolemia from burn patients is measured during 28 days. The relation between the cortisolemia and values from 16 plasma amino acids is studied on the fourth and on the seventh day after injury. Cortisolemia is higher in the severely burned patients than in mild injured patients. A correlation between the burn surface area and the cortisolemia is found on day four and on day seven. Cortisolemia is also higher in nonsurvivors than in survivors. Plasma methionine, on day four, and plasma phenylalanine, on day seven, are correlated with cortisolemia. This result suggests that hyperphenylalaninemia results from protein breakdown which is essentially cortisol-mediated. However, cortisol does not seem to have a central place in control of amino acidemia after burn injury.
Amino Acids↗
Plasma and urinary amino acid pattern in severe burn patients-evolution throughout the healing period.
Plasma and urinary amino acids were measured in 12 severely burned adults (20% of body surface area or more). Measurements were made on the day of injury, and seven times thereafter until the 28th day after trauma. During the first 7 days, a decrease in plasma concentrations of some glucose precursor amino acids and an increase of phenylalanine were observed. Plasma concentrations of branched-chain amino acids, proline, ornithine, lysine, and tyrosine remained unchanged until the 3rd wk, then rose markedly. Plasma aspartate, hydroxyproline, and methionine were unchanged throughout the study. Urinary output increased in varying degrees for each amino acid considered. Urinary isoleucine was the only amino aicd that did not increase after burn trauma.
Adolescent↗
Insulin-like growth factor I/somatomedin C action on 2-deoxyglucose and alpha-amino isobutyrate uptake in chick embryo fibroblasts.
Maximum 125I-IGF-I/Sm-C total binding to chick embryo fibroblasts was 3% at +37 degrees C and decreased to less than 1% in presence of 2.8 X 10(-9) M unlabelled IGF-I/Sm-C. Insulin did not compete with IGF-I/Sm-C for the binding to cells. Biological action of IGF-I/Sm-C was evaluated on 2-deoxyglucose and alpha-aminoisobutyrate uptake. Results are compared with those obtained with insulin. Maximal peptide effects on the two transport processes were obtained at a 0.65 X 10(-7) M concentration and for a 120 minute association time, whereas cells were markedly less sensitive to insulin and time response curves were different. These results suggest that insulin action on nutrient uptake in chick embryo fibroblasts is not mediated by the binding of the hormone to IGF-I/Sm-C receptors.
Aminoisobutyric Acids↗
Effect of nutritional state of brain-dead organ donor on transplantation.
OBJECTIVE: We describe the effect of the metabolic and nutritional modifications caused by severe illness or injury in brain-dead organ donors on transplant organ function. Malnutrition is frequently found in brain-dead organ donors and nutrients may interfere with different organ functions. METHODS: Literature was obtained from MEDLINE using the key words organ donation, brain death, transplantation, nutrition, fish oil, amino acids. RESULTS: In the liver, infusion of large quantities of dextrose can restore glycogen reserves but may induce hyperglycemia and a hyperosmolar hepatic state. Feeding improves protein synthesis in hepatocytes, and fat (fish oil) administration in particular increases the hepatic energy and adenosine triphosphate content. Amino acids have a significant effect on regenerating hepatic tissue when given with fat and glucose. In the heart, free fatty acids administered during reperfusion improve cardiac functional recovery, and administration of propofol, a general anesthetic agent enriched with fatty acids, have protective effects on ischemia-and-reperfusion injury. Glutamine also can induce graft protection during ischemia-and-reperfusion injury. Renal function is improved by fish oil supplementation. In addition, effective renal plasma flow, glomerular filtration rate, and renal blood flow are increased, apparently by a reduction in thromboxane B2 production. Glycine or alanine can protect renal tubules from stress injury. CONCLUSION: Nutrition plays an important role in the modulation of organ function after transplantation.
Amino Acids↗
Glutamine as an activator of immune cells: how does it work?
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Glutamine↗
Portal hyperglutamatemia after dietary supplementation with monosodium glutamate in pigs.
The aim of the present work was to examine in pigs the effect of a dietary supplementation with the flavor enhancer monosodium glutamate (MSG) on intestinal amino acid metabolism. For this purpose, pigs weighing 60 +/- 2 kg received a standard meal twice a day for 1 week, supplemented with either 10 g MSG per meal or, as control experiments, an isonitrogenous amount of glycine together with an equal amount of sodium in the form of NaCl, the animals being their own control in all experiments. At the end of this period, pigs received a MSG or glycine-NaCl-supplemented meal and samples of portal and arterial blood were collected for amino acid analysis in plasma. The results demonstrate after MSG supplementation rapid significant increases in glutamate concentration in the portal and arterial blood plasma after a test meal which resulted in a positive portoarterial difference. In comparison, after glycine-NaCl supplementation, glutamate concentrations were almost identical in portal and arterial plasma. Furthermore, significant increased aspartate concentration in the portal blood plasma was observed after MSG supplementation when compared with control experiments. When enterocytes were isolated at the end of the supplementation period from the jejunum and examined for their metabolic capacities towards L-glutamate and L-glutamine, it was found that metabolism did not differ according to the supplement used, with glutamate and glutamine being oxidized and transaminated at a similar level. It is concluded that the portal hyperglutamatemia observed shortly after the ingestion of a MSG- supplemented meal is likely due to the saturation of the intestinal capacity to metabolize glutamate with no measurable adaptation of the metabolic pathways controlling glutamate metabolism in enterocytes.
Alanine↗
Induction of a catabolic state in rats by dexamethasone: dose or time dependency?
BACKGROUND: Daily injections of dexamethasone (DEX) given to adult rats are a recognized but nonstandardized model of stress. The aim of this work was to establish a reproducible and accurate model of stress in adult rats by chronic injection of DEX in order to standardize it. For this purpose, the effect of the duration of treatment and the effect of DEX dose were tested. To help understand the mechanisms of the catabolic effect of DEX, the study was extended to the metabolism of glutamine (GLN). In experiment 1, 60 male Sprague-Dawley rats (3 months old) were divided into 8 groups of 6 rats: groups G3, G5, G7, and G9 received 1.50 mg/kg/d of DEX by intraperitoneal (i.p.) injection for 3, 5, 7, or 9 days, respectively. Groups G3PF, G5PF, G7PF, or G9PF were pair-fed to groups G3, G5, G7, or G9, respectively. Group AL (n = 12) was healthy rats fed ad libitum. RESULTS: In treated rats, nitrogen balance reached its lowest value at day 5. After 9 days treatment by DEX, the catabolic state was reduced. An increase in GLN-synthetase activity and a decrease in muscle GLN content were related to DEX per se not to DEX-induced anorexia. In experiment 2, 25 rats were divided into 5 groups of 5 animals. Groups G0.75, G1.50, and G2.50 received 0.75, 1.50, and 2.50 mg/kg/d, respectively, of DEX by i.p. injection for 5 days. Group PF was pair-fed to group G2.50 and group AL was control rats. RESULTS: DEX induced a decrease in nitrogen balance that was dose-independent. GLN-synthetase activity was increased maximally in gastrocnemius by 0.75 mg/kg. CONCLUSIONS: Five days of treatment by DEX and a dose of 0.75 mg/kg/d induced a marked catabolic state.
Animals↗
Metabolic effects of arginine addition to the enteral feeding of critically ill patients.
BACKGROUND: Some studies have suggested that the addition of arginine to enteral feeding solutions may improve outcome in critically ill patients, but the mechanism is incompletely explained. In particular, the availability and utilization of arginine administered enterally is not well defined. METHODS: This prospective, randomized, double-blind, placebo-controlled study performed in a Department of Medicosurgical Intensive Care included 51 patients likely requiring long-term enteral feeding. Thirty-seven patients (57 +/- 7 years, SAPS II 33 +/- 6) completed the 7-day study, of whom 20 received the formula enriched with free arginine (6.3 g/L) and 17 received an isocaloric and isonitrogenous control solution. Arginine absorption was assessed from plasma arginine concentrations in serial samples. Three pathways of arginine utilization were explored: (1) the production of nitric oxide, assessed by the plasma concentration of nitrite/nitrate (NOx) and citrulline, and 24-hour urinary excretion of NOx; (2) the protein turnover, estimated by the phenylalanine concentrations; and (3) the activity of arginase, reflected by the ornithine concentration. RESULTS: The plasma concentrations of arginine and ornithine increased in the group fed with the enriched formula (from 55 +/- 9 micromol/L to 102 +/- 9 micromol/L and from 57 +/- 7 to 135 +/- 11 micromol/L, respectively, p < .05), but not with the control formula. There was no difference between groups in either NO production or phenylalanine concentration. CONCLUSIONS: Supplemental arginine in enteral feeding is readily absorbed, and mainly metabolized into ornithine, presumably by the arginase enzyme.
Arginase↗
Amino acid metabolism in thermal burns.
Burn injury induces time-dependent variations in plasma amino acids, ie, an initial hyperaminoacidemia reflecting proteolysis in the wound areas, a decrease in gluconeogenic amino acids a consequence of excessive utilization in the liver, and a progressive return to normal. There is also a durable hyperphenylalaninemia, reflecting increased protein turnover and specific alterations of sulfur amino acids. In burned rats, the same general pattern is observed, except that glycine rather than alanine and glutamine exhibits the largest variations. Improvements in nutritional support with regard to the amino acid composition of diets are envisaged.
Adolescent↗
Action of enterally administered ornithine alpha-ketoglutarate on protein breakdown in skeletal muscle and liver of the burned rat.
Several studies concerning burn patients have shown that supplementation of enteral nutrition with ornithine alpha-ketoglutarate (OKG) favorably modifies protein metabolism. Therefore, the effect of OKG administration on muscular and hepatic protein catabolism was evaluated in burned rats. Four groups of six rats were used. Two groups were scalded by immersion of the dorsum in water at 90 degrees C for 10 seconds and then starved for 24 hours. Controlled enteral nutrition was then administered in three boluses daily (Osmolite, 210 kcal/kg/d, 1.2 g N/kg/d); one group was supplemented with OKG (5 g/kg/d, ie, 0.68 g N/kg/d), while the other group received an equivalent amount of nitrogen in the form of glycine. One group of healthy control rats received Osmolite supplemented with glycine and the last group was fed ad libitum. The animals were killed after 2 days of nutrition. Protein catabolism was assessed in vitro by measuring the amount of valine (liver catabolism) and phenylalanine (muscle catabolism) released into the incubation medium of isolated tissues. Tissular and serum glutamine were also assayed. Burn injury induced muscle hypercatabolism without affecting hepatic catabolism. The administration of OKG limited both muscle weight loss and muscle protein hypercatabolism and significantly improved the muscle glutamine pool. These results demonstrate the nitrogen-sparing effect of OKG in muscle in hypercatabolic states.
Animals↗
Ornithine alpha-ketoglutarate and glutamine supplementation during refeeding of food-deprived rats.
The aim of this study was to compare the efficiency of ornithine alpha-ketoglutarate (OKG) and glutamine supplementation in an experimental model of denutrition that provides well-characterized disturbances of amino acid patterns. Male Wistar rats (187 +/- 11 g; five in each group) were starved for 3 days and then refed for 7 days with an oral diet (192 kcal kg-1.day-1 and 2.25 g of nitrogen kg-1.day-1), supplemented with 0.19 g of nitrogen kg-1.day-1 in the form of OKG, glutamine, or casein (control group). Food deprivation induced a fall in most tissue amino acids, with the notable exception of muscle leucine and liver glutamate, which increased by 43% (p < .01), and 11% (p < .05), respectively. The main effect of OKG was seen in the viscera, with a normalization of most amino acid pools (including proline and branched-chain amino acids) in the small bowel and liver. The main effect of glutamine was observed in the muscle, with a normalization of the glutamine and leucine pools. We conclude that, in this model and with the doses used, OKG and glutamine act in different target tissues, ie, splanchnic areas and muscle, respectively.
Acid-Base Equilibrium↗
Urinary urea nitrogen prediction of total urinary nitrogen.
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Humans↗
TNF-alpha and IL-6 synergistically inhibit ketogenesis from fatty acids and alpha-ketoisocaproate in isolated rat hepatocytes.
BACKGROUND: During sepsis, lipid metabolism is shunted toward triacylglycerol synthesis and hepatic lipogenesis. A decrease in ketogenesis from free fatty acids also is observed, probably mediated by cytokines involved in host response to infection. Whether such an inhibition of ketogenesis occurs with other ketone body precursors such as ketoacids is not known. The aim of this study was to determine the effects of tumor necrosis factor alpha (TNF-alpha) and interleukin 6 (IL-6) on hepatic ketone body production from octanoic acid, a medium-chain fatty acid, and from alpha-ketoisocaproate (KIC), the ketoanalogue of leucine. METHODS: The experiments were conducted in cultured hepatocytes isolated from 24-hour-fasted Sprague-Dawley rats. Hepatocyte monolayers were incubated for 6 hours, with either KIC or octanoic acid (1 mmol/L), in the presence of glucagon and TNF-alpha (25 micro/L) IL-6 (15 microg/L) and/or IL-6. Acetoacetate, beta-hydroxybutyrate, and free fatty acids were determined in culture medium by enzymatic methods and KIC was measured by high-performance liquid chromatography. RESULTS: KIC and octanoic acid uptake by hepatocytes was 79% and 92%, respectively, over 6 hours, and cytokines had no influence. However, TNF-alpha and IL-6 caused inhibition of ketogenesis from alpha-ketoisocaproate (5.6% +/- 2.3% and 4.4% +/- 3.0%, respectively), and from octanoic acid (7.9% +/- 2.9%, 5.7% +/- 3.2%, respectively). In addition, when the two cytokines were present together in the culture medium, the inhibition was enhanced (inhibition of ketogenesis from KIC: 14.0% +/- 4.8%; from octanoic acid: 11.6% +/- 3.4%). CONCLUSIONS: In our experimental conditions, cytokines mediate an inhibition of ketogenesis; this process could be explained by a direct effect of cytokines on metabolic pathways of octanoic acid and KIC oran indirect effect by modification of the mitochondrial redox state.
3-Hydroxybutyric Acid↗
Protein metabolism in rats during long-term dietary restriction: influence of aging.
BACKGROUND: Protein depletion is frequent in the elderly, but the underlying mechanisms are not yet fully understood. In particular, it is unknown whether there is a defect of adaptation to a restriction of food intake in the elderly. This study was performed to compare the effects of 6-week dietary restriction (DR) on protein metabolism in both adult and aged rats. METHODS: Adult (3-month-old) and aged (22-month-old) rats were acclimatized for 2 weeks and then fed a standard diet for 6 weeks, either ad libitum (control adult [C(Adult)] and aged [C(Aged)] rats) or with only 50% of the average intake of the second week of acclimatization (restricted adult [R(Adult)] and aged [R(Aged)] rats). Protein metabolism, in terms of tissue protein content, nitrogen balance, and 3-methylhistidine (3-MH) urinary excretion, was evaluated. RESULTS: C(Adult) rats gained 30.4% of initial weight, whereas the body weight (BW) of C(Aged) rats was maintained. DR induced a rapid decrease in BW during the first 2 weeks in R(Adult) rats, but afterward BW remained stable. In R(Aged) rats, BW loss was linear during the 6 weeks and significantly higher than for R(Adult) rats (p<.01). In both restricted groups, muscle protein content was moderately affected by DR, whereas DR induced a marked decrease in visceral protein content. Nitrogen balance was decreased by DR but stayed positive in R(Adult) rats, whereas it became null in R(Aged) rats. CONCLUSIONS: In terms of protein metabolism, aged rats adapted less efficiently than adult rats to a long-term dietary restriction.
Aging↗
[Does the impact factor the single suitable criteria to judge the quality of a scientific paper?].
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Bibliometrics↗