Enzymatic determination of carbon-14 labeled L-alanine in biological samples.
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Alanine↗
Biomedical subjects
A Palou
Publications and source records attributed to A Palou.
Amino-acid-enzyme activities in brown and white adipose tissues and in the liver of cafeteria rats. Effects of 24 hours starving.
Moderate obesity (17% excess body weight) was induced in female rats by offering a "cafeteria" diet during 82 days. The adaptive changes in five amino-acid-metabolism enzymes were determined in liver and white- and brown adipose tissues by comparison with chow fed controls both in the fed and 24-h starved states. Plasma urea levels were lower in the obese and the changes in enzymatic activities pointed to a lower rate of amino-acid metabolism in our dietary obesity group. The levels of activity of amino-acid-metabolism enzymes in brown adipose tissue were higher than in white adipose tissue and in most cases comparable to that of liver. The importance of amino acids as a fuel source in brown adipose tissue thermogenesis cannot be ruled out.
AMP Deaminase↗
Tissue glycogen and lactate levels in starved and in protein-fed domestic fowl chicks (Gallus domesticus).
The levels of glycogen, protein and lactate in the tissues of 3- and 5-day-old domestic fowl chicks either starved or fed a protein diet (hard-boiled egg white) have been studied. The patterns of change in the parameters studied were much similar in both experimental groups compared to fed controls. Tissue and circulating levels of lactate were very low in protein-fed chicks, they are lowest in the starved ones. Plasma glucose levels were diminished in starved and protein-fed groups vs. controls, as were their tissue glycogen levels, the latter being lowest in starved chicks. The availability of dietary amino acids could not prevent the effects of the lack of dietary carbohydrate observed in starved chicks, as the weight of liver, circulating glucose and lactate levels were significantly lowered in these animals compared with controls.
Animals↗
Amino acid compartmentation in chick blood during the peri-hatching period.
Individual amino acid levels and compartmentation in chick blood were measured on day 20 of incubation, at hatching (day 0), or after 1 or 5 days of free life, and compared with those of adult chickens. Blood cell amino acid concentrations were almost one order of magnitude higher than those of plasma, with higher values than those found in mammalian erythrocytes. This difference may be due to the capability for protein synthesis of the nucleated cells coupled with a postulated utilization of amino acids as fuel. The most common pattern of individual plasma amino acid levels was a slight rise at hatching followed by a large decrease, with minimal values for adults. The patterns in the cells did not always coincide with those for plasma. Total blood amino acid levels increased steadily during the period studied due to the increase in intracellular amino acids, giving rise to increasing blood-cell/plasma concentration ratios. These changes showed higher availability of plasma amino acids just after hatching, while the cell concentrations increased steadily to the maximum values in adults. The increase in alanine levels in cells with little changes in plasma can be correlated with the role of this amino acid as the main 2-amino nitrogen carrier in the avian bloodstream. The high amino acid levels in the cells suggest that these cells act as inter-organ transporters and reservoirs of amino acids, they have a different role in their handling and metabolism from those of mammals.
Age Factors↗
Effect of starvation and protein-feeding on blood amino acid compartmentation of domestic fowl hatchlings.
The amino acid concentrations in plasma and blood cells of 5-day old domestic fowl hatchlings that received either standard feeding, protein-feeding or were starved have been determined. The effects of 5-day starvation or protein feeding did not alter significantly the combined amino acid concentration of blood plasma, but decreased blood cell levels. The patterns of individual amino acid changes observed in starvation or protein-feeding were similar in both groups when compared with those of controls. However, starvation-induced effects were actually more marked than those observed in protein-fed animals. The patterns of change with starvation of individual amino acids in the hatchling blood compartments were very different from those observed in mammals subjected to short or medium-term starvation. The mechanisms controlling circulating amino acid concentrations act in both situations studied to maintain the plasma amino acid concentrations despite marked changes in the availability of 2-amino nitrogen energy to the animal; changes in blood amino acid compartmentation buffering plasma amino acid availability.
Amino Acids↗
Tissue glycogen and lactate handling by the developing domestic fowl.
The levels of glycogen and lactate in liver, intestine, yolk sac membrane and leg and breast muscle of domestic fowl from day 10 of "in ovo" development to day 5 after hatching compared with adults have been measured and compared with the circulating concentrations in blood of glucose and lactate. Glycogen stores in most tissues increased before hatching to attain a minimum around the eclosion and then increased to adult values in muscle and liver. Lactate maintained its plasma concentrations with higher effectiveness than plasma glucose, which increased steadily up to adult levels from hatching. The study of tissue vs plasma lactate concentration ratios suggests a general activation of lactate metabolism from hatching, coinciding with the ingestion of carbohydrate-based food. Both muscles studied, as well as intestine, seem to be net lactate producers; blood cells can speculatively be considered as lactate users and liver maintains its concentration of lactate very close to that plasma, suggesting a fast utilization of this material as well as liver being the main site for control of circulating lactate.
Aging↗
Tissue glycogen and lactate handling by the developing domestic fowl.
The levels of glycogen and lactate in liver, intestine, yolk sac membrane and leg and breast muscle of domestic fowl from day 10 of "in ovo" development to day 5 after hatching compared with adults have been measured and compared with the circulating concentrations in blood of glucose and lactate. Glycogen stores in most tissues increased before hatching to attain a minimum around the eclosion and then increased to adult values in muscle and liver. Lactate maintained its plasma concentrations with higher effectiveness than plasma glucose, which increased steadily up to adult levels from hatching. The study of tissue vs plasma lactate concentration ratios suggests a general activation of lactate metabolism from hatching, coinciding with the ingestion of carbohydrate-based food. Both muscles studied, as well as intestine, seem to be net lactate producers; blood cells can speculatively be considered as lactate users and liver maintains its concentration of lactate very close to that of plasma, suggesting a fast utilization of this material as well as liver being the main site for control of circulating lactate.
Aging↗
Effect of starvation and a protein diet on the amino acid metabolism enzyme activities of the organs of domestic fowl hatchlings.
The activities of alanine and aspartate transaminases, adenylate deaminase, glutamine synthetase and glutamate and xanthine dehydrogenases have been measured in liver, yolk sac membrane, intestine and breast and leg muscle of domestic fowl hatchlings receiving for 3 or 5 days either a standard diet or hard boiled eggwhite as well as in 3 or 5 days starved animals. The patterns of activation of amino acid metabolism enzymes were fully comparable in protein-fed and starved groups with respect to fed controls; the differences with respect to the latter became more marked in 5- than in 3-days old chicks. In 5-days old chicks intestine alanine transaminase activity increased in parallel to that of liver in protein-fed animals but not in those starved, in agreement with an enhanced alanine transfer between both organs under this situation. Both, starvation and protein-feeding, induced a general decrease in the amino acid metabolizing ability of muscle. Glutamine (but not alanine) synthetizing capabilities were enhanced.
AMP Deaminase↗
Sex differences in blood amino acid concentration and cell/plasma distribution in the domestic fowl.
The amino acid concentration of and distribution between the cell and plasma of the blood of male and non-laying female domestic fowl have been determined. No significant differences in plasma amino acid content were observed between the sexes, except for higher serine and lower asparagine concentrations in the female. Hens had higher intracellular concentrations of aspartate, hydroxyproline, arginine, lysine and cystine and lower concentrations of cysteic acid and taurine. The proportion of amino acids carried in the blood cells of fowls was about 80%, a value that is much higher than that found in mammals. The mean ratio of combined total amino acid concentrations between plasma and cells was about 8-fold, again much higher than the corresponding figures in mammals.
Amino Acids↗
Liver- and muscle amino-acid concentrations during the development of domestic fowl.
The concentrations of free amino acids in liver, leg muscle and wing muscle of developing domestic fowl chicks were measured and compared with those of adults. Leg and breast muscles showed a remarkably parallel pattern of change in free-amino-acid concentrations during development up to day 5 after hatching, in agreement with their lack of differentiation up to day 5. Liver free-amino-acid concentration pattern with the development were very similar to those of the muscles, in significant difference with Mammals. Adult free tissue amino acids were lower than those of developing chicks. Most changes in amino-acid concentration in chick tissues were observed around hatching, and have been tentatively attributed to changes in diet. Combined amino acids changed very little during the period studied in muscles and liver. Taurine constituted a very big share of total amino acids.
Age Factors↗
Amino-acid metabolism enzyme activities in the liver, intestine and yolk sac membrane of developing domestic fowl.
To contribute to our understanding of nitrogen metabolism in the developing chick we have studied in liver, intestine and yolk sac membrane the ontogeny of both aspartate- and alanine transaminases, glutamate dehydrogenase, adenylate deaminase, glutamine synthetase and xanthine dehydrogenase activities. Liver enzyme activities were much higher than those of the same enzymes in intestine and yolk sac membrane, the latter having the lowest activities. In the liver, both alanine transaminase and glutamate dehydrogenase increased their activity just before hatching, xanthine dehydrogenase and glutamine synthetase develop their highest activity just after hatching, while aspartate transaminase and adenylate deaminase attained the highest levels just with adulthood. From the pattern of enzyme activity in yolk sac membrane and intestine it can be inferred that after hatching, the amino-acid metabolism in these tissues is considerably enhanced, with higher production of ammonia from amino acids, as indicated by the rise in adenylate deaminase, as well as increased potentiality in production of both alanine and glutamine. It can be concluded that hatching coincides with a deep change of pace in amino-acid metabolism in the organs studied fully comparable with that observed in Mammals at the end of lactation, with the difference that the adaptation to the new diet in the case of the chick is much more sudden than weaning is for the rat.
AMP Deaminase↗
Enzymatic lactate-specific radioactivity determination in biological samples.
A method for the measurement of specific lactate radioactivity in biological samples is presented. It is based on the following steps: (a) enzymatic conversion of lactate to pyruvate, (b) pyruvate conversion to 2,4-dinitrophenylhydrazone, (c) concentration-separation of the latter in reusable Amberlite XAD-7 polymeric adsorbent columns, and finally (d) estimation of the radioactivity thus retained compared with that of enzymatically untreated aliquots of the same samples. Specificity was ensured by the use of lactate dehydrogenase as specific recognizing agent for lactic acid. No interference from glucose, lactate, or amino acids was observed. The method presented is simple and can be applied in routine multiple estimations of lactic acid radioactivity in conjunction with the enzymatic measurement of lactate in biological samples in tracer metabolic studies.
Animals↗
Patterns of amino acid enzyme in domestic fowl breast and leg muscle during development.
Activities of alanine and aspartate transaminases, glutamine synthetase, adenylate deaminase, glutamate and xanthine dehydrogenases and lactate dehydrogenase were measured in leg and breast muscles of developing chicks from day 10 in ovo to day 5 of free life, and compared with measurements for adult hens. Xanthine dehydrogenase activity was low in both muscles with adult levels attained on day 15 in ovo. Glutamine synthetase for chicks was maintained higher during development than for adults in both muscles. Minor differences were observed between both muscles in all enzymes tested up to day 18. With low embryonic values and important rises before hatching, the differences were initiated in the posthatching period. Important differences were observed between adult levels of activity. Leg muscle revealed higher enzyme values except for lactate dehydrogenase and indistinguishable levels for adenylate deaminase and xanthine dehydrogenase in both muscles. Alanine, instead of glutamine, is postulated as the main nitrogen transport between muscle and liver in the domestic fowl.
AMP Deaminase↗
Activities of amino acid metabolizing enzymes in the stomach and small intestine of developing rats.
The activities of aspartate and alanine transaminase, serine dehydratase, arginase, glutamate dehydrogenase, adenylate deaminase and glutamine synthetase were determined in the stomach and small intestine of developing rats. Despite the common embryonic origin of the intestine and stomach, their enzymes showed quite different activity levels and patterns of development, depending on their roles. Most enzyme activities were low during late intrauterine life and after birth, attaining adult levels with the change of diet at weaning. No arginase activity was found in the stomach and no changes were detected in adenylate deaminase in the stomach or intestine throughout the period studied. Alanine transaminase, serine dehydratase and, to some extent, glutamine synthetase levels, significantly higher in late intrauterine life, decreased after birth, suggesting that the foetal stomach has a transient ability to handle amino acids.
AMP Deaminase↗
An enzyme specific method for estimation of pyruvic acid radioactivity in biological samples.
A method for the estimation of pyruvate radioactivity in complex biological samples is presented. After perchloric acid deproteinization, the samples were divided in two aliquots. All pyruvate was removed from the first aliquot with lactate dehydrogenase and NADH; the other was left undisturbed. Then all hydrophilic components of the sample were removed through an Amberlite XAD-7 column. The samples were treated with dinitrophenylhydrazine to obtain the corresponding hydrazones, which were retained in an Amberlite XAD-7 column and then were eluted with acetone and their radioactivity counted. The difference between both aliquots corresponded to the pyruvate radioactivity in the sample. No contamination by lactate, glycerol, glucose or amino acids was observed. The mean recovery of 5 determinations of pyruvate radioactivity was 91.3% +/- 1.0.
Acrylic Resins↗
Arginase activity during pregnancy and lactation.
Arginase activity in liver, kidney, small intestine and stomach of pregnant and lactating rats as well as their plasma levels have been measured. Late pregnancy as well as weaning induced a parallel increase in enzyme activity that is not reflected in the circulating urea levels. The arginase activity changes have been related to known changes in feeding and nitrogen handling patterns as well as to hormonal variations.
Animals↗
Effects of 24-hour starvation period on metabolic parameters of 20-day-old rats.
The effects of a 24-hour starvation period upon 20-day-old rat pups were studied both in animals kept in the presence of their starved dams and in their absence. The relative loss of body weight was more intense in the rats that received no milk, being however, severe in both groups. There was a significant maintenance of both plasma glucose levels and total amino acids, with differences in blood glucose compartmentation and a remarkable uniformity in the effects of starvation upon individual amino-acid concentrations. A significant increase in plasma urea was observed, higher in the rats kept in the presence of the dam. Ketone bodies increased with starvation but their final levels were lower than in adults. The general pattern of metabolic change observed suggests a situation, after 24-h food deprivation, similar to that of long term starvation in adults; with an active protein amino-acid catabolism but with a remarkable maintenance of circulating foodstuff levels.
Amino Acids↗
[Adenohypophysis secretion in children: comparison between a combined test and isolated stimulation tests].
Pituitary function is assessed by a combined test (insulin, TRH, LH-RH) in twenty prepubertal children with constitutional delay of growth and/or retarded bone maturation, and is compared with another group of 31 children with the same diagnostic assessed by an isolated test. Plasma GH, TSH, PRL and cortisol levels had not interferences when the provocation stimuli were administrated in combined form or isolated one. When basal cortisol levels were near 25 mcg/100 ml, the insulin induced hypoglycemia did not lead higher values. Simultaneous evaluation of pituitary function can assessed in a short period of time (two hours) with minimum disturbs in children and exhibits a good information of the hypothalamo-pituitary axis.
Blood Glucose↗