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X Remesar

Publications and source records attributed to X Remesar.

175 records · Page 10Linked to original sources
PubMed1980

Plasma amino-acid concentrations during development in the rat.

The plasma individual amino-acid concentrations in the rat during late foetal development and from the birth to the end of the weaning have been studied. Both the very low foetal amino-acid degrading capabilities in addition to the high amino-acid concentration ability of the placenta help to sustain considerably high plasma foetal amino-acid levels that favour considerably protein synthesis. There is a very important decrease in most amino-acid concentrations with birth, due to the cessation of placental transfer, relative immaturity of intake and assimilation processes and to the highly anabolic environment found in the pup. The changes in postnatal development plasma amino-acid patterns reflect directly the availability of amino acids in the diet, the maturation of the amino-acid metabolism pathways and transport systems and their use for protein synthesis (and other nitrogenous compounds). The main situation that affects individual amino-acid levels is the shift from high biological value milk protein to low biological value plant proteins in the rat chow pellets. The postnatal development is characterized by a high combined total amino-acids homeostasis with ample changes in individual amino-acid concentrations, that is maintained in spite of the deep changes in diet, size, metabolism, hormone environment, maturation, etc. observed in the rat from birth to weaning and adulthood.

Aging↗
PubMed1980

Fasting-induced changes of tyrosine transaminase activity in rat tissues.

Tyrosine transaminase activity in liver, kidney, intestine, stomach, skin, adipose tissue, striated muscle and brain in fed and 24-hour fasted rats, has been studied. Maximal activity has been found in liver, with only fractional activity in the other tissues. 24 hour fasting induced significant decrease in liver and adipose tissue activity, while no changes have been detected in the other tissues. The possible implications of these facts are discussed.

Animals↗
PubMed1980

Blood and plasma glucose relationships during pregnancy, the breeding cycle and development in the rat.

The concentration of blood and plasma glucose in developing, pregnant and post-partum rats has been determined under uniform conditions of housing, feeding and circadian rhythms. The glucose content of erythrocytes and of the plasma compartment has been estimated using the packed cell hematocrit value as correction factor. During pregnancy and fetal development there were significant reductions in the proportion of intracellular glucose, and significant increases during the suckling and weaning period. There was no direct relationship with plasma insulin levels. Results are discussed in relation to aspects of metabolism specific to the physiological components of the breeding cycle studied; plasma glucose homeostasis is held very constant; both intraerythrocytic and plasma concentrations should be considered when studying glucose homeostasis in given physiological situations.

Animals↗
PubMed1980

Effect of 24-hours fast on aspartate transaminase activities in the organs of the rat.

The aspartate transaminase activity of liver, kidney, brain, stomach, small intestine, striated muscle, skin and adipose tissue of fed and 24-hour fasted rats has been studied. The activity level of the enzyme is very much alike in most organs when expressed per unit of protein or DNA weight, in accordance with the general metabolic role of this enzyme. The activity of skin and adipose tissue is considerably lower than that of the other studied organs. A 24-hour fast induced significant increases in the activity of all organs except intestine and stomach.

Animals↗
PubMed1980

Serine dehydratase activity in the liver and extrahepatic organs of fed and 24-hour fasted rats.

The serine dehydratase activity in crude homogenates of rat liver, intestine, adipose tissue, kidney, brain, leg striated muscle, skin and stomach, both in fed and 24-hour fasted rats have been estimated. The liver enzyme activity increased twofold with fasting, while it did not affect the serine dehydratase activity in any other organ studied. The highest serine dehydratase activity is found in the liver, with only fractional activity in all other tissues studied.

Animals↗
PubMed1980

Effect of chronic feeding of Remington's diet and fasting on rat plasma composition.

Rats fed on Remington's low iodine diet (supplemented with iodine) and on rat chow were compared as to their plasma composition. There are significant differences in plasma glycerol, aceto-acetate, beta-hydroxybutyrate and in several amino acid concentrations, mainly lysine and tryptophan. 24 hours of fasting lowered the differences between the groups, but some aspects remained unchanged, i.e. the low lysine and tryptophan concentrations in Remington diet fed rats. The use of the Remington diet therefore, provoked a functional lack of these amino acids, even when their concentration in the diet was higher.

Amino Acids↗
PubMed1978

Different expressions for enzyme activities in organs of rat. Application to aspartate transaminase, glutamate dehydrogenase and AMP-deaminase.

The widely used activity expressions for enzyme levels in tissues are discussed: microkatals per unit of tissue weight, protein weight, and DNA weight. The expression of microkatals present in a definite organ in reference to a standard animal weight, 100 g in the case of rat, is also used. The different expressions are applied to aspartate transaminase, glutamate dehydrogenase and AMP deaminase activities in liver, hind leg striated muscle and kidneys in rat. The conclusion is reached that measurements of enzyme activity in tissues should be expressed in more than one form, as the information drawn from one could differ substantially from that obtained from other, giving artifactual views of the metabolic role played by the enzyme in a given tissue.

Adenosine Deaminase↗
PubMedDate not supplied

Urinary free cortisol excretion pattern in morbid obese women.

The urinary excretion of free cortisol in a group of 10 control and 20 morbidly obese women was measured in all bladder voidings during 24 h. The data from obese women were measured under Hospital basal controlled conditions and after 3 days of very low calorie diet (VLCD, 1.9 MJ/d). The hourly cortisol excretion pattern was determined for each woman, and means of each group were computed in order to obtain a 24 h excretion pattern. In controls, the highest excretion rate was in the morning (8-9 h) and the lowest at 21-22 h. Inbasal conditions, the obese showed a similar but flatter pattern; the highest peak was also in the morning (9-10 h), but the lowest rate was between 21 and 24 h. The VLCD diet flattened the pattern even more, in away that no clear peak was observed from the early morning until the afternoon; however, the nadir coincided with that found in basal conditions. These patterns resulted in significant differences between VLCD, basal diet and control. The amount of free cortisol excreted was 93.0 +/- 6.9 nmol/ day in controls, 70.1 +/- 4.7 nmol/day in obese under basal conditions and 62.6 +/- 3.0 nmol/day when subjected to VLCD. The results presented are consistent with a lower overall cortisol secretion in the morbid obese women, which also show a narrower margin of variation in cortisol secretion than non-obese controls. The data also show the significant influence of dietary energy on the pattern of cortisol excretion in obese women.

Adult↗
PubMedDate not supplied

Effect of food deprivation and refeeding on rat organ temperatures.

Small thermocouple sensors were surgically implanted in the liver, kidney, hind leg muscle, interscapular brown adipose tissue, small and large intestines, dorso-lumbar internal side of the skin, periovaric adipose tissue and the lower aorta of Wistar rats. The aortic temperature was taken as core temperature. The sensors allowed continuous long-term monitoring of the temperatures of these organs. A period of 18 hours of food deprivation resulted in an overall decrease of mean core and organ temperature, brown adipose tissue temperature dropping to values lower than those of the aorta in the fed state. Liver, kidney and small intestine maintained higher temperatures than the aorta both in fed and starved states. Refeeding overshot the core temperature with increases in most organs versus both the fed and food-deprived situations. The results are concordant with an active role of brown adipose tissue in dietary induced thermogenesis. Three days of food deprivation did not alter the basic circadian rhythm of core temperatures in the rat kept at 22 degrees C, whereas it did modulate both nightly maximum and diurnal minimum temperatures to much lower settings than either in the fed or refed situations. The rat adapts to starvation by decreasing core and organ temperatures and widening the amplitude of the daily temperature cycle.

Adipose Tissue, Brown↗
PubMedDate not supplied

Dietary sucrose supplementation fails to modify fat deposition in lean or obese rats.

The effects of sucrose supplementation on body composition and heat production were studied in lean, dietary (cafeteria diet) and genetically (Zucker fa/fa) obese adult (60 days) rats. Sucrose supplement (29 kJ) for 10 days did not result in significant changes in the pattern of energy (fat) deposition or carcass composition. There were no alterations, either, in heat production measured by direct calorimetry. Under the conditions studied, sucrose intake did not affect lipid deposition or thermogenesis.

Adipose Tissue↗
PubMedDate not supplied

Analysis of ultradian heat production and aortic core temperature rhythms in the rat.

The rhythms of aortic core temperature and overall heat production in Wistar rats was analyzed by using long series of recordings of temperature obtained from implanted thermocouple probes and heat release values from a chamber calorimeter. There was a very high degree of repetitiveness in the presentation of actual heat rhythms, with high cross-correlation values ascertained wit paired periodograms. No differences were observed between heat production between male and female adult rats. The cross-correlation for temperature gave similar figures. The cross-correlation study between heat production and aortic core temperature in the same animals was significant and showed a displacement of about 30 minutes between heat release and aortic core temperature. The analysis of heat production showed a strong predominance of rhythms with periods of 24 hours (frequencies < 11.6 microHz) or more; other rhythms detected (of roughly the same relative importance) had periods of 8 or 2.2 hours (35 or 126 microHz, respectively). The analysis of aortic core temperature showed a smaller quantitative contribution of the 8 or 2.2 hours (35 or 126 microHz) rhythms, with other harmonic rhythms interspersed (5.1 and 4.0 hours, i.e. 54 and 69 microHz). The proportion of 'noise' or cycles lower than 30 minutes (< 550 microHz) was higher in internal temperature than in the actual release of heat. The results are in agreement with the existence of a basic period of about 130 minutes (126 microHz) of warming/cooling of the blood, with a number of other harmonic rhythms superimposed upon the basic circadian rhythm.

Activity Cycles↗
PubMedDate not supplied

Effect of cold-exposure on rat organ blood flows.

Rat tissue blood flows and heart output were determined in adult Wistar rats under up to two hours of cold (4 degrees C) exposure, using radioactive 46Sc microspheres. Circulating glucose, lactate and triacylglycerol levels were also determined. Glucose concentrations increased with cold exposure in spite of the drainage of substrates induced by the activation of thermogenesis. Plasma triacylglycerol levels agree with a high involvement of fats in the sustenance of heat production. Cold-exposure had an immediate effect decreasing skin circulation, but increased that of muscle and brown adipose tissue. Kidney and intestine blood flows were maintained. In liver, blood flow increased progressively with cold-exposure. White adipose tissue showed--at first--low blood flow, but increased in parallel to that of liver. The data presented show a distribution of the blood in the body of the cold-exposed rat in which thermogenic responsibilities and supply of blood are evenly distributed throughout. The importance of haemodynamic changes in brown adipose tissue was considerable but the increased share of muscle blood flow suggests that it may have a global role in maintaining thermal homeostasis.

Adipose Tissue↗