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Biomedical subjects

E Herrera

Publications and source records attributed to E Herrera.

At least 163 records · Page 9Linked to original sources
PubMed1983

Circulating triacylglycerols, lipoproteins, and tissue lipoprotein lipase activities in rat mothers and offspring during the perinatal period: effect of postmaturity.

Mammary gland and adipose tissue lipoprotein lipase activities have been implicated in the changes of circulating triacylglycerol levels which occur in the mother at late gestation. In the newborn the temporal accumulation of triacylglycerols in the liver coincides with the appearance of a lipoprotein lipase peak. The relationships of these changes with the rise in circulating prolactin in the mother before parturition and the extrauterine nutritional status in the offspring were studied in a postmaturity model produced in the rat by subcutaneous injection of 7 mg progesterone/day to pregnant animals from the 20th day of gestation. Pregnant controls received the medium. Parturition occurred at day 21.5 of gestation in pregnant controls while it did not occur before the 23rd day in those receiving progesterone. At the 20th day of gestation, plasma triacylglycerol concentrations and all lipoprotein fractions (especially VLDL) were much higher in mothers not receiving progesterone than in age-matched virgins, and these differences disappeared at the 21st day of gestation. Lipoprotein lipase activity was maintained low in control mothers' adipose tissue until the 23rd postfecundation day while it greatly increased in mammary gland from parturition time. In progesterone treated mothers, both triacylglycerol and lipoprotein fractions (especially VLDL) in plasma were maintained elevated until the 23rd postfecundation day and adipose tissue and mammary gland lipoprotein lipase activities were maintained low until this time.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1983

Effects of streptozotocin-diabetes and L-thyroxine treatment on TSH and GH, and circulating glucose and glycerol in thyroidectomized rats.

The response to exogenous thyroxine in thyroidectomized rats made diabetic by treatment with streptozotocin was greatly impaired, as shown by their growth retardation and the lack of increase in plasma GH and pituitary GH and TSH concentrations. Insulin administration partially compensated for these endocrine alterations in diabetic thyroidectomized rats. When these animals received enough exogenous thyroxine to normalize their plasma PBI and TSH levels, insulin administration did not decrease their augmented glucose and glycerol concentrations. These findings show the permissive action between thyroid hormones and insulin although some effects of the former counteract those of insulin.

Animals↗
PubMed1983

Effects of alcohol ingestion in the pregnant rat on daily food intake, offspring growth and metabolic parameters.

1. Daily food intake, fluid consumption, offspring growth and metabolic parameters were studied in rats receiving ethanol in the drinking water before, during and after gestation. 2. Ethanol treatment always reduced daily food, liquid and caloric intake in the rat, except during gestation when total daily caloric intake was greater in rats receiving ethanol than in control animals. The increase in both food and liquid intake during lactation in controls was also observed in alcohol-deprived mothers but was significantly reduced in mothers maintained under alcohol treatment. 3. Offspring from alcohol-treated mothers were retarded in body weight and size compared with controls, the differences becoming greater as the suckling period advanced. 4. The 15 day-old pups from alcohol-treated mothers had reduced glucose and augmented beta-hydroxybutyrate levels in blood, and markedly reduced liver glycogen concentrations, indicating their acutely malnourished state. 5. In pups from mothers that received alcohol until the 21st day of gestation, body weight and size were normalized at the 15th day but skeletal maturation and liver glycogen concentration were reduced and blood acetoacetate and beta-hydroxybutyrate were augmented as compared with values in pups from control mothers. If these parameters are interrelated, metabolic changes may be used for early diagnosis of fetal alcohol syndrome.

Aging↗
PubMed1983

Method for the study of metabolite transfer from rat mother to fetus.

Infusion medium containing a tracer was introduced through the left uterine artery to 20.5-day pregnant rats. In this way, the left uterine horn received the tracer directly while it reached the right horn after dilution in the mother's circulation. When U-14C-D-glucose or U-14C-L-alanine was infused, radioactivity in fetal blood from the left uterine horn was 3 or 8 times higher respectively than in the right horn and 2 or 6 times higher than in maternal blood. When the infusion was carried out with 125I-labelled growth hormone, which is known not to cross the placental barrier, very little radioactivity was found in fetuses compared with that in the mother's plasma and no differences were observed in blood radioactivity levels of fetuses from either horn. After infusion of U-14C-D-glucose through the maternal jugular vein instead of left uterine artery, radioactivity was the same in fetuses from the left and right horns, indicating that manipulations of the left uterine side did not greatly affect its circulation. These findings. together with the determination of specific radioactivity of the tracer used in both maternal and fetal plasma, validate the technique as a semiquantitative means to determine the direct transfer of any product through the placental barrier in the rat.

Alanine↗
PubMed1983

Effects of streptozotocin diabetes and insulin treatment on adipose tissue glucose utilization in the rat.

[U-14C] glucose utilization by pieces of epididymal fat-pad was studied in streptozotocin-diabetic rats, food-restricted animals, and normal controls. Both CO2 and fatty acids formation were greatly reduced in tissues from the diabetic animals treated or not with insulin and this change was milder in tissues from food-restricted rats. A positive correlation was found between [14C] glucose utilization in vitro and plasma RIA-insulin levels when values from all animals were pooled. The percentual response to high doses of insulin was small in adipose tissue from streptozotocin-diabetic animals for CO2 and total lipids formation, but it was high for fatty acids synthesis; the response in food-restricted animals was high and was greatly augmented in tissues from the streptozotocin-diabetic rats treated with insulin. Results indicate that in adipose tissue from streptozotocin-diabetic animals the alteration of insulin responsiveness occurs distal to the receptor events and that impaired basal glucose metabolism is a direct consequence of their hypoinsulinemia.

Adipose Tissue↗
PubMed1983

Method for triglyceride measurement in small amounts of plasma.

A method is described for determining triacylglyceride concentration in small amounts of plasma. After ethanolic-KOH digestion of diluted plasma aliquots, samples were neutralized with MgSO4 and glycerol was fluorimetrically assayed in supernatants by the coupling of glycerokinase, pyruvate kinase, and lactate dehydrogenase catalyzed reactions. Values were corrected by free glycerol present in the non-digested samples. Digestions were performed at different times and temperatures in order to establish optimum conditions for recoveries and reproducibility. Parallel determinations before and after phospholipid removal showed that their presence in plasma did not interfere with the obtained values. This method is especially useful for running many samples in parallel and for determinations in small experimental animals in which the amount of plasma is very limited.

Fluorometry↗
PubMed1982

Comparative changes with age of the fasting response in circulating ketone bodies, glucose and insulin and oral glucose tolerance test in the rat.

1. Body weight loss in 48 hr fasted rats decreased with age. 2. Blood glucose and plasma RIA-insulin levels correlated negatively and positively respectively with body weight in fed rats. Fasting produced a greater fall in blood glucose and a smaller decrease in RIA-insulin in young than in old rats. 3. Blood ketone bodies correlated negatively with body weight after 48 hr fasting. 4. In oral glucose tolerance tests, blood glucose rose more in adult and old rats than in prepuberals when both fed and fasted. RIA-insulin levels rose more in prepuberals than in older rats when fed but not when fasted. 5. Changes in body composition and reduced insulin sensitivity with age are discussed.

Aging↗
PubMed1982

Effects of maternal ethanol ingestion on cerebral neurotransmitters and cyclic-AMP in the rat offspring.

1. To study the effects of maternal alcohol ingestion on brain parameters in offspring, rats were given ethanol for drinking (25% w/v) from the time of mating until sacrifice. Controls drank tap water. 2. Alcohol ingestion reduced daily food and liquid consumption but total caloric intake was only slightly diminished. 3. Maternal body weight increased and offspring body weight, size and brain weight were reduced in the animals receiving alcohol. 4. Brain concentrations of tryptophan, tyrosine and GABA were augmented in ethanol treated mothers at 1 day post-partum. 5. Comparison of brain parameters in offspring of alcoholic mothers with those of controls showed that tryptophan and 5HT concentrations were augmented in 4 day old neonates, NA was increased in 21 day fetuses and 1 day old neonates, and adenylate cyclase activity was also greater in the brains of 21 day fetuses and the cerebellums of 4 day old neonates. 6. Neither phosphodiesterase nor cyclic-AMP concentrations differed in offspring of alcoholic and control mothers. 7. Data showed alterations in brain NA and 5HT systems in the offspring of alcoholic mothers.

Amines↗
PubMed1982

Effects of streptozotocin-diabetes and l-thyroxine treatment on plasma amino acid levels in thyroidectomized rats.

1) Thirty days after surgical thyroidectomy, one group of rats were made diabetic by treatment with streptozotocin and were studied for the next 14 days. These diabetic thyroidectomized animals were similar in body weight to their thyroidectomized controls but had higher plasma concentrations of most amino acids. 2) Treatment with 0.5, 1.0 or 2.0 micrograms of L-thyroxine/100 g body wt for 7 days prior to sacrifice produced no changes in either parameter in the diabetic thyroidectomized animals. On the contrary, in thyroidectomized controls, the L-thyroxine treatment was followed by a dose-dependent increment in body weight. In these animals, the administration of 0.5 microgram of L-thyroxine per day was associated with a marked rise in the plasma level of most amino acids, while only basic amino acid levels increased with 1.0 microgram, and levels decreased with 2.0 micrograms. 3) In the diabetic thyroidectomized rats treated with insulin for the last 7 days before sacrifice, body weight gain and the biphasic change of plasma amino acid levels were restored. 4) It is proposed that treatment of thyroidectomized controls with small doses of L-thyroxine accelerate protein breakdown accompanied by minor changes in amino acid utilization, while this latter effect increases with higher doses of the hormone. 5) Present results demonstrate that a certain amount of circulating insulin is required to obtain the response to exogenous thyroxine in diabetic thyroidectomized animals. Results are discussed in terms of the role of interhormone synergism as it affects normal sensitivity of the different hormones.

Amino Acids↗
PubMed1982

Fetal and Early postnatal development of adenylate cyclase and cyclic AMP phosphodiesterase activities in rat brain.

Brain cyclic AMP metabolism was studied in rat offspring at 17, 19 and 21 days of intrauterine life and 0, 1 and 4 postnatal days. Wet weight and protein and DNA and RNA concentrations in brain increased in parallel with body weight until the 4th postnatal day although during the perinatal phase some of these parameters suffered a manifest temporal retardation. In the brain, similar qualitative changes were observed in both adenylate cyclase and high Km cyclic AMP phosphodiesterase activity while the low Km enzyme showed a rise from 17-day fetuses to those of 19 days with no further changes. The increase in cyclic AMP concentration was very mild and the values found in the 21-day fetuses were already similar to those in adults. In the mother's brain a significant reduction in adenylate cyclase activity appeared at 19 and 21 days of gestation. The retardation in the ontogenic development of cyclic AMP metabolism during the perinatal phase in offspring is probably a consequence of their specific metabolic situation while in the mother it may be the result of its endocrine preparation for parturition.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1981

Metabolic effects of short term food deprivation in the rat.

The effects of food deprivation for up to 24 hours on plasma metabolic parameters in the rat have been studied. Liver dry weight and glycogen content dropped significantly from 3 hours of food deprivation onwards. Total muscle glycogen supplied about as much glycosyl residues or precursors as did the liver. Plasma glucose, urea, lactate and total and essential amino acids decreased significantly from 3 hours of fasting onwards. Glycerol, free significantly from 3 hours of fasting onwards. Glycerol, free fatty acids, beta-hydroxybutyrate and acetoacetate showed significant increases with fasting. Alanine, serine, arginine, threonine, aspartate plus asparagine and proline showed significant decreases with fasting. Several other amino acids showed almost no change with fasting. Lysine, leucine plus isoleucine and taurine showed biphasic changes in their concentrations with a minimum at 6 hours and a transient recovery at 12 hours of fasting Essential amino acids decreased more than the non essential ones. With fasting there is a shift in ammonia disposal with lower urea concentrations as nitrogen is better conserved. The results seem to suggest that there is a constant release of substrates, through liver and peripheral tissue proteolysis, that is counteracted by differential utilization of amino acids during fasting.

Amino Acids↗
PubMed1981

"In Vitro" utilization of labelled esterified fatty acids and glyceride glycerol from triglyceride-rich lipoproteins in rat adipose tissue.

Triglyceride-rich lipoproteins (chylomicrons and very low density lipoproteins) were labelled "in vivo" by injecting (U-14C)-glycerol and (9-10(n)-3H)-palmitate in female rats. After purification, these lipoproteins contained most of the 3H in esterified fatty acids and the 14C in glyceride glycerol of neutral lipids. This preparation was incubated "in vitro" in the presence of either isolated adipocytes or epididymal fat pad pieces from male rats. With the incubation, a certain proportion of both 3H-esterified fatty acids and 14C-glyceride glycerol disappeared from the medium, the effect being greater when the incubations were performed with adipocytes than with fat pad pieces. Much greater radioactivity appeared in the lipids of adipocytes than in those of fat pad pieces at the end of 60 or 120 min incubation, and the incorporation of 3H being relatively greater than that of 14C. With the latter isotope, the label appeared not only in the glyceride glycerol fraction but also in the free and esterified fatty acids. Although it is known that lipoproteins lipase activity is lower in adipocytes than in fat pad pieces, our results indicate that, in the former preparation, the enzyme may be more accessible for the substrate. These data also demonstrate that glycerol released by the hydrolysis of lipoprotein glycerides may be partially incorporated into lipids by adipose tissue.

Adipose Tissue↗
PubMed1981

Tryptophan overload in the pregnant rat: effect on brain amino acid levels in in vitro protein synthesis.

The concentration of most amino acids was higher in the brains of 19- and 21-day rat fetuses than in their respective mothers. After an intraperitoneal load of tryptophan to the mother, the intracerebral concentration of several amino acids (including leucine) decreased not only in the mothers, but also in their fetuses. The in vitro incorporation of [3H]leucine into proteins in brain postmitochondrial supernatant fractions was enhanced in both the mothers and fetuses after tryptophan administration, but this effect disappeared when protein synthesis was calculated by using specific activities corrected for the amount of unlabeled leucine in the preparation. By this criterion, protein synthesis activity appeared similar in the brains of 19- and 21-day pregnant rats but was higher in their fetuses, especially in the 21-day subjects. Thus, protein synthesis in the brain was not altered by marked changes in the amino acid pool and more profound and prolonged metabolic disturbances must occur to cause permanent damage in the developing brain.

Amino Acids↗
PubMed1981

Lipids and lipoproteins in maternal and fetus plasma in the rat.

Plasma lipidic components appear augmented in 19- and 21-day pregnant rats compared with virgin controls, the greatest effect being in triglycerides, corresponding to the augmented proportion of plasma very low density lipoproteins (VLDL). The plasma lipidic components in fetuses of 19 and 21 days are lower than in their mothers, the greatest decrease occurring in triglycerides. In the plasma of 19-day fetuses, there is only one lipoprotein electrophoretic band which corresponds to the beta-lipoproteins of adults (low density lipoproteins, LDL) according to its mobility and floating characteristics, while in the fetus of 21 days there are also pre-beta-lipoproteins (VLDL). In the 1- and 5-day-old newborns, the four main lipoprotein fractions are already present as in the adults. The late appearance of VLDL and the lack of high density lipoproteins in the rat fetus determine various specific metabolic characteristics.

Age Factors↗
PubMed1981

Morphological and compositional changes of rat plasma triglyceride-rich lipoproteins incubated with adipose tissue.

Triglyceride-rich rat lipoproteins (mainly VLDL), purified by ultracentrifugation and dialysis, were incubated for 120 min in the presence of epididymal fat-pad pieces from fed rats in media containing heparin. During this process, the lipoproteins were depleted of triglycerides and proportionally enriched with proteins, causing their increased density. After incubation, electron microscopic study of the triglyceride-rich lipoproteins revealed partially degraded structures, and some particles had atypical discoid flattened form and marked lamellar structure. These findings are in agreement with those of Blanchette-Mackie & Scow (1976) in triglyceride hydrolysed chylomicrons and confirm their observation of monolayers formed by accumulated lipolytic products that move by lateral diffusion, giving rise to a spiral fold between the core triglycerides and the aqueous space.

Adipose Tissue↗