PubMed Health⌕ Search

Biomedical subjects

J P Barlet

Publications and source records attributed to J P Barlet.

14 recordsLinked to original sources
PubMed1979

Foetal plasma magnesium levels during maternal hypo- or hypermagnesaemia in ewes.

1. The influence of maternal hypo- or hypermagnesaemia of foetal plasma magnesium levels was studied in pregnant ewes between the 120th and the 145th day of gestation using a permanent catheter inserted in utero into the left aorta of the foetus on the 115th day of gestation. 2. In seven ewes, carrying eleven foetuses, the injection of 1 alpha-hydroxycholecalciferol induced a hypomagnesaemia which lasted 72 h. This had no significant effect on foetal plasma Mg levels. 3. In five ewes, carrying six foetuses, hypermagnesaemia induced by a 2 h magnesium chloride infusion had no significant effect on foetal plasma Mg levels. 4. These results provide evidence that in sheep during the last 20 d of gestation the foetal regulation of plasma Mg is independent of the maternal plasma Mg levels.

Animals↗
PubMed1979

Fetal blood calcium response to maternal hypercalcemia induced in the cow by calcium infusion or by solanum glaucophyllum ingestion.

Bovine fetuses chronically catheterized in utero during the last month of gestation were used to study the relationships of maternal-fetal calcium and phosphate levels. Calcium infusion into the pregnant cows induced a rapid and marked increase in maternal plasma calcium but no change in fetal plasma calcium concentrations. Oral administration of Solanum glaucophyllum to the mother for 6 days raised the plasma concentrations of calcium and phosphate in both the mother and the fetus.

Animals↗
PubMed1977

Plasma parathyroid hormone and calcitonin levels in hypocalcaemic magnesium-deficient calves.

Mg deficiency was experimentally induced in 3 calves given Mg-deficient semi-synthetic milk (10 mg of Mg/l of milk). Three control calves received the same milk supplemented with Mg (190 mg of Mg/l of milk). Calcium and vitamin D contents of this milk were similar to that of natural milk. Daily weight gain in control calves was similar to that observed in calves given natural milk. The daily weight gain of Mg-deficient calves was not statistically different from that of control calves during the first 6 weeks of Mg-deficiency. Then clinical symptoms of Mg-deficiency appeared (loss of appetite, nervousness, tetany crises). In these Mg-deficienct animals a fall in plasma magnesium level, followed by hypophosphataemia and then by hypocalcaemia was observed. During the whole experimental period plasma CT and plasma PTH levels were not statistically different in Mg-deficient and in control calves. These results show that the hypocalcaemia observed in Mg-deficient calves was due neither to an increase in CT secretion nor to a decrease in PTH secretion. Nevertheless, the parathyroid glands from these animals seem unable to react satisfactorily to the hypocalcaemia induced by Mg-deficiency.

Animals↗
PubMed1976

Calcium metabolism in newborn animals: the interrelationship of calcium, magnesium, and inorganic phosphorus in newborn rats, foals, lambs, and calves.

The plasma concentrations of calcium, inorganic phosphorus, and magnesium were studied during the early postnatal period in a rodent (rats), in ruminants (lambs and calves), and in foals. Decreases in plasma calcium after birth were observed only in newborn rats and foals. In rats the postnatal fall in plasma calcium level was already evident 1 hr after cesarean section (9.20 mg/100 ml) as opposed to 11.90 mg/100 ml in utero) and reached a nadir within 6 hr (-4.05 mg/100 ml). Newborn foals showed a small decrease in plasma calcium (-0.73/100 ml) 48 hr after birth. In the four species plasma inorganic phosphorus increased in the days after birth; plasma magnesium levels were only slightly affected over the first week of life. In ruminants and in foals, the high plasma calcitonin levels were not always related to plasma calcium, nor with plasma inorganic phosphorus over the first week of life. Newborn calves showed at birth detectable levels of plasma parathyroid hormone, similar to those found in their mothers, with individual values ranging from 0.80-3.50 ng/ml. These results are discussed in light of the well known early neonatal nypocalcemia occurring in normal human newborns.

Animals↗
PubMed1976

A radioimmunoassay for bovine parathyroid hormone.

A radioimmunoassay for bovine parathyroid hormone (bPTH) has been developed. An antibody was raised in a goat against 1-84 b PTH which was directed against the carboxy-terminal part of the molecule (no cross-reactivity with synthetic 1-34 b PTH fragment). 1-84 b PTH was labelled with 125I using the chloramine-T method. The tubes were incubated at 4 degrees C for 6 days in an equilibrium system with 25% protein concentration. Separation was performed using plasma-coated charcoal. Jugular venous plasma PTH levels were shown to be increased in hypocalcemic parturient cows.

Animals↗
PubMed1975

[Influence of somatostatine on plasma level of calcitonin in the calf and the swine].

In young calves receiving intraveinously a small dose of calcium to stimulate calcitonin release, intraveinous infusion of somatostatin did not significantly modify the jugular veinous plasma calcitonin levels measured by radioimmunoassay, using a porcine system which cross-reacts with bovine calcitonin. In piglets, intraveinous infusion of somatostatin also did not change the jugular veinous plasma calcitonin concentration.

Animals↗