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Biomedical subjects

G Cabello

Publications and source records attributed to G Cabello.

At least 55 records · Page 3Linked to original sources
PubMed1985

Plasma free and total iodothyronine levels in hypophysectomized and intact lamb foetuses during the last third of gestation.

The changes in plasma levels of thyroxine (T4), free thyroxine (free T4), triiodothyronine (T3), free triiodothyronine (free T3), and reverse triiodothyronine (rT3) were observed in intact or hypophysectomized lamb foetuses during the last third of gestation. Hypophysectomy was performed at two stages: 100 and 120 days of gestation. Cord blood was collected after Caesarean section. In intact foetuses, T4 and free T4 levels increased significantly between day 100 and 120 of gestation, but decreased from day 132 to birth. T3 levels, low until day 132, rose abruptly during the last 12 days of gestation, as did the T3/free T4 ratio. Free T3 levels, relatively high on day 100, decreased until day 130 to rise during the last days of gestation. Reverse T3 levels, high since day 100, increased sharply until day 132 as did the reverse T3/free T4 ratio, and then declined. In hypophysectomized foetuses, undetectable or very low levels of T4, free T4 and rT3 were observed on day 120 and 144. T3 levels, although decreased by pituitary destruction, remained at 39.7% (120 days) and 21.4% (144 days) of the values recorded in intact foetuses. Free T3 levels, normally depressed at the end of gestation, were not affected by hypophysectomy on day 120. When hypophysectomy was performed later, the levels of T4, free T4 and rT3 were slightly increased on day 144 as compared with those of the other hypophysectomized foetuses. This study confirms the changes in the plasma iodothyronine levels observed previously in the lamb foetus.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Cortex Hormones↗
PubMed1983

Endocrine reactivity (T3, T4, cortisol) during cold exposure in preterm and full-term lambs.

The endocrine reactivity to a short-term cold exposure (+ 4 degrees C during 1 h 30 min) was studied in 8 full-term (FT) and 12 preterm (PT) Limousin x Romanov lambs, obtained by oestrogen injections to the ewes; 4 PT animals died (PTD) during the observation period and 8 remained alive (PTA). The plasma cortisol, T4 and T3 levels were lower in PT lambs (particularly in PTD for T4 and T3) during the first hours of life. Moreover, rectal temperature decreased sharply between birth and 30 min postpartum in the PT group; at this time, plasma T3 levels and rectal temperature were positively related. During cold exposure, the plasma cortisol levels increased in FT lambs, but did not change in the PT group. Moreover, the plasma T4 levels rose slightly in FT animals (+ 12%), increased sharply in PTA lambs (+ 137%), or showed a small decrease in the PTD group (-5%) in which a marked hypothermia occurred; the relative changes in the circulating T4 levels were positively related to the algebraic variations of rectal temperature in PT lambs. However, the changes in the plasma T3 levels did not parallel that of T4 in the three groups of animals, but a positive relationship was observed, in all lambs, between the circulating T3 levels and the rectal temperatures at the end of the cold exposure. These results suggest a reduced sensitivity of the adrenal cortex to stressful conditions in PT lambs. Moreover, they underline the importance of thyroid function for thermoregulation in the newborn lamb, particularly in PT animals.

Animals↗
PubMed1983

Changes in the concentration of thyroxine in the plasma of rat fetuses during late gestation: influence of ligation of the maternal uterine vein and artery.

Plasma thyroxine levels were detectable in rat fetuses from day 17 of pregnancy and increased exponentially from 3.48 +/- 0.13 (S.E.M.) nmol/l to 11.33 +/- 0.90 nmol/l at birth. Ligation of the maternal uterine vein and artery, performed on day 17 of pregnancy, significantly reduced both the fetal growth rate, observed initially on day 19 of pregnancy (controls: 2.24 +/- 0.02 g; fetuses from ligated horns: 1.71 +/- 0.03 g, P less than 0.001) and plasma thyroxine levels, observed initially on day 20 of pregnancy (controls: 6.56 +/- 0.13 nmol/l; fetuses from ligated horns: 5.41 +/- 0.13 nmol/l, P less than 0.001). In addition we observed positive relationships between plasma thyroxine levels and body weights of the two groups on days 20 and 21 of pregnancy and at birth. These results suggest that relationships observed between plasma thyroxine levels and body weight in fetuses or newborn animals may be explained by the common effect of the placental blood flow mediated by fetal nutrition.

Animals↗
PubMed1983

Intestinal K99+ escherichia coli adhesion and absorption of colostral IgG1 in the newborn lamb: effect of fetal infusion of thyroid hormones.

Continuous infusion of thyroid hormones during the last 12 days of gestation in ovine fetuses was associated with: a reduction of the rate of appearance of blood IgG1 after colostrum feeding in the newborn lambs; an important reduction of the number of jejunal cells filled with IgG1, 12 hours post partum, suggesting a premature closure of the intestinal permeability to IgG1; and a significant reduction of the K99+ Escherichia coli adhesion on the intestinal villi. These results could partly explain relationships observed previously between perinatal thyroid function abnormalities and the occurrence of neonatal diseases.

Adhesiveness↗
PubMed1982

Absorption and half-life of bovine, caprine and ovine IgG1 in the newborn lamb. Effect of experimental prematurity and endocrine factors.

The influence of experimental prematurity and endocrine factors on the absorption and half-life of bovine IgG1 was studied in newborn Limousin x Romanov lambs. Six preterm and six full-term animals were bottle-fed with a common bovine colostrum pool during 32 h, whereas seven preterm and six full-term lambs were fed with the same bovine colostrum 2 h post-partum, a caprine colostrum 8 h after birth and an ovine colostrum 16 h post-partum. In the first group, the maximal plasma IgG1 levels were not affected by experimental prematurity; however, the duration of the Ig absorption period seemed to be longer in preterm lambs. In the second group, absorption of blgG1 given at the first feeding was depressed in experimental preterm animals, whereas no difference remained for clgG1 given at the second feeding, and at the third feeding, olgG1 were better absorbed than in full-term lambs. This set of data indicates that the duration of the Ig absorption period was longer in preterm than in full-term lambs. The results obtained confirm the importance of thyroid function for acquisition and maintenance of passive immunity : plasma T4 levels were negatively related to the maximal plasma IgG1 levels in the first group of lambs, and positively related to the half-life of IgG1 in all animals. On the other hand, cortisol was negatively related to IgG1 absorption, at least during the first hours of life. The half-life of clgG1 in the plasma of the lambs was not modified by experimental prematurity, and was no different from the half-life of blgG1 in preterm lambs. However, the half-life of blgG1 was significantly lower in full-term than in preterm animals. This observation suggests that a mechanism of recognition of heterologous IgG1 could mature during the last 9 days of gestation.

Animals↗
PubMed1981

Hormonal status in the newborn lamb (cortisol, T3, T4). Relationships to the birth weight and the length of gestation: effect of the litter size.

The experiments reported involve 18 Romanov lambs born spontaneously between 135 and 145 days of gestation. Their birth weights ranged between 1.22 and 3.55 kg. The neonatal changes in plasma cortisol, triiodothyronine and thyroxine levels were observed from birth to 30 days postpartum, and related to the length of gestation and the birth weight. Positive correlations were found between: (1) plasma T3 (2, 4, 8 h and 11 days after birth), T4 levels (4 h after birth) and the birth weight; (2) plasma T3 levels (2, 4 and 8 h after birth) and the weight gain during the 1st month of life, and (3) plasma cortisol levels at birth, 8 and 48h postpartum and the litter size. Negative correlations were found between: (1) plasma cortisol levels (at birth, 2, 4, 8 and 48 h postpartum) and the birth weight; (2) plasma cortisol levels (2, 8 and 48 h after birth) and the length of gestation, and (3) values of the T3/T4 ratio and the litter size. A tentative scheme of the interactions between litter size, hormonal plasma levels, length of gestation and birth weight is proposed. Moreover, the effects of placental insufficiency and insufficient plasma levels of thyroid hormones could explain partly the high frequency of disease which occurs in low birth weight lambs.

Animals↗
PubMed1981

Absorption of colostral IgG1 by the newborn lamb: influence of the length of gestation, birthweight and thyroid function.

The relationships between the length of gestation, the birthweight, thyroid and adrenocortical function, and the absorption of colostral IgG1 were studied in 18 Romanov lambs born spontaneously between 135 and 145 days of gestation. All the lambs were bottle-fed in accurately standardised conditions with a bovine colostrum pool. Negative relationships were observed between the maximum plasma IgG1 levels and the length of gestation, the birthweight, or the plasma thyreostimulin levels near birth and between the times at which the maximum plasma IgG1 levels occurred and the length of gestation, or the plasma thyroxine levels near birth. The half-lives of bovine IgG1 in the plasma of the lambs were also related to the plasma thyroxine level at birth. These results suggest that maturity of the newborn lamb, assessed by the length of gestation and the hormonal status, could greatly influence the acquisition and maintenance of colostral immunity.

Animals↗
PubMed1980

Comparative absorption of colostral IgG1 and IgM in the newborn calf. Effects of thyroxine, cortisol and environmental factors.

Twelve Holstein x Friesian calves, born in the same stable, and then transferred to outside individual boxes, were used in this experiment. Six animals received thyroxine (T4) injections at birth and after 24 h. All the calves received the same colostrum in the same conditions. The following results were obtained: --The capacity of calves to acquire colostral IgG1 and IgM varies considerably between individuals. --T4 injections do not noticeably alter IgG1 and IgM absorption, but thyroxinemia at birth, reflecting probably the fetal level, is negatively correlated with the absorption periods of IgG1 and of IgM. --We have observed positive correlations between the maximum plasma levels of IgG1 and IgM, and between the times at which they were reached, but this time is shorter for IgM than for IgG1. --The outside temperature at birth is negatively correlated with the maximal IgG1 concentration. --IgM are less well absorbed by the calves than IgG1 (percentages of absorption: 17% for IgM and 75% for IgG1). This result suggests that the intestinal absorption of immunoglobulins could be selective in the calf.

Animals↗
PubMed1979

Neonatal changes in the plasma levels of cortisol, cortisone and aldosterone in the calf.

Plasma levels of cortisol, cortisone and aldosterone were measured during the first 20 days of life in 10 healthy calves. Cortisolemia, high at birth, decreased from birth to day 15. Changes in plasma cortisone were similar to those of cortisol. The value of the cortisol/cortisone plasma ratio increased from birth to day 8 and remained steady until day 20. A positive correlation was found between plasma levels of cortisol and cortisone, during the 6- to 20-day period; no correlation was observed before that. These results raise the question of whether, as is assumed in the human, maternal cortisol would cross the placenta with conversion to cortisone in the bovine. Plasma aldosterone increased from day 1 to day 3, and decreased steadily until day 20 when its level was very low. Negative correlation found between the values of aldosterone and sodium led us to think that natremia regulation by this hormone could be functional in the neonatal calf.

Age Factors↗
PubMed1978

Semi-automated determination of hormonal iodine without incineration.

A sensitive semi automated technique for the determination of hormonal iodine is described. The thyroid hormones are isolated by means of a cation exchange resin (Dowex 50 Wx2). The iodine atoms are liberated from the organic molecules with bromine, without prior incineration or destruction (moidified Pileggi's method). Then, mineral iodine is measured colorimetrically with a Technicon autoanalyzer. This technique seems particularly adapted to a programme of standardisation because of its sensitivity and reproductibility. It is well adapted to the determination of circulating hormonal iodine of the ruminants, in which the concentration is lower than in man.

Animals↗
PubMed1978

The effects of thyroxine and climatic factors on colostral gammaglobulin absorption in newborn calves.

Observations of 68 Friesian and Holstein X Friesian calves in a single herd with low neonatal mortality gave the following results: --The calves which will suffer from diarrhoea but survive were in a hyperthyroid state (high levels of hormonal iodine, T3 and free thyroxine index) compared with the healthy animals. --The concentration of plasma globulins, after colostrum intake was lower in diarrhoeic subjects calves than in the healthy ones. --For the whole group of animals, plasma hormonal iodine, at birth, was negatively correlated with the concentration of plasma globulins at 48 hours (r = 0,37, P less than 0,05). Thus, by reducing the absorption capacity of colostral globulins, an excess of thyroid hormones at birth could increase young calves sensitivity to various infections. To test this hypothesis, 12 Holstein X Friesian calves, born in the same stable and then transferred to outside individual boxes, were used. Six animals received thyroxine injections at birth and after 24 hours. All the calves received colostrum in the same conditions. The following results were obtained. --All the treated calves became ill (1/6 of the controls), independantly of their plasma IgG1 concentrations. --The capacity of calves to acquire colostral IgG1 varies considerably between individuals (maximum IgG1 concentrations and, probably, duration of intestinal absorption of IgG1). --The T4 injections at birth do not noticeably after IgG1 absorption. --Thyroxinemia at birth, reflecting the foetal concentration, is negatively correlated (r = 0,74, P less than 0.01) with the period of IgG1 absorption. --The outside temperature at birth is negatively correlated with the maximum IgG1 concentration (r = 0.78, P less than 0.01). These results indicate that a hyperthyroid state at birth, and, probably, during foetal development compromise the calves health: --by direct or indirect action, the intermediates of which are not known, --by reducing the period of intestinal absorption of immunoglobulins in addition. Moreover climatic factors such as ambient temperature at birth may influence acquisition of passive immunity.

Animals↗
PubMed1977

[Influence of age on the plasma hormonal iodine response to thyrotropin injection in young calves].

The influence of age upon the increase in plasma hormonal iodine level following an intravenous injection of bovine TSH (0.2 USP units/kg) was studied in young jersey calves. The response to TSH increased between birth and the 7th day, then decreased regularly until the end of the third month. Reasons for these variations are discussed according to some results obtained following TSH injections.

Aging↗
PubMed1977

Composition of blood plasma (calcium, phosphorus, magnesium, proteins) during the neonatal period in the calf. Influence of the state of health.

The changes in plasma concentrations of calcium, phosphorus, magnesium and several protein fractions, were studied from birth to the age of twenty days in 68 calves. 32 animals remained healthy while 36 animals suffered from diarrhea but survived. The day of birth the two groups differed biochemically. During the whole period studied, calcemia, phosphatemia and albuminemia of diarrheic calves were systematically lower than those of animals showing no pathologic symptoms. In addition, after intake of colostrum, the increase in total proteins and globulins was much smaller in sick calves than in those which remained healthy. The possible causes of these anomalies and their roles in the appearance of pathology are discussed.

Animals↗