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Biomedical subjects

E Mallet

Publications and source records attributed to E Mallet.

At least 127 records · Page 7Linked to original sources
PubMed1983

[Current function tests in hypoparathyroidism in children].

In clinical practice, we can now directly measure the level of circulating parathormone and we can also assess its impact on its renal effector by the assay of cyclic adenosine monophosphate. The radio-immunoassay of parathormone uses antisera with amino or carboxy terminal specificity. The preferential antibody has amino-terminal specificity in as much as the biological activity resides in this part of the hormone, so that the levels measured with this antibody reflect the levels of biologically active parathormone. However, the levels detected with antisera with carboxy-terminal specificity are much more discriminating in cases of hormonal hypersecretion in pseudohypoparathyroidism, because of the prolonged survival time of the fragments detected. The study of the sensitivity of the renal receptor to parathormone is based on the Ellsworth-Howard test. The plasma cyclic AMP gradient is measured following injection of exogenous parathormone. The results demonstrate a definite absence of response in the pseudohypoparathyroid children studied compared to normal and hypoparathyroid children. In children with hypoparathyroidism, the response is rapid with a maximal level of cyclic AMP obtained at 10 minutes. The gradient can be as much as 20 times the baseline level. The study of the sensitivity of the bone receptor to parathormone is based on classical tests whose results are difficult to evaluate, like changes in the serum calcium and the total urinary hydroxy-proline obtained after an injection of exogenous parathormone.

Adolescent↗
PubMed1983

[Value of gastroesophageal scintigraphy for the detection of gastroesophageal reflux in infants].

50 children with a strong clinical suspicion of gastroesophageal reflux and 10 control patients were evaluated with gastroesophageal scintiscans. 500 muCi à 1 mCi of Tc sulfur colloid mixed the patients' routine milk or formula feeding was administered and serial images of the abdomen and thorax were obtained. A positive scintiscan was found in 35 patients (sensitivity 70%) and none of the controls (specificity 100%). A comparison of findings in 34 patients referred for both radiographic and radionuclide studies showed that barium studies were positive in 38% and radionuclide in 64.7%. We found this examination to be more sensitive that the standard barium radiography particularly in patients with respiratory symptoms. We concluded that the GE scintiscan is complementary to barium studies in the diagnosis of GE reflux. Pulmonary aspiration of gastric contents was detected in only a case of the 35 patients with documented GE reflux. A T 1/2 emptying gastric longer than 90 minutes (linear calculation) or 105 minutes (exponential calculation) is an indirect GE reflux test. This procedure is simple, safe more physiologic than other available examinations.

Gastroesophageal Reflux↗
PubMed1982

Coupling defect of thyrotropin receptor and adenylate cyclase in a pseudohypoparathyroid patient.

A patient with type I pseudohypoparathyroidism was found to have mild hypothyroidism. The patient had an elevated basal TSH level and an exaggerated TSH response to TRH. There was no goiter despite increased TSH levels, and the 131I thyroidal uptake was low before and after exogenous TSH administration. These studies suggested that the patient might have partial resistance to TSH. The binding of radioiodinated TSH to thyroid membranes obtained by biopsy was next studied. The displacement of iodinated TSH by unlabeled TSH was found to be identical to that in normal control membranes. The adenylate cyclase stimulation by a supramaximal dose of TSH, however, was blunted (120.1 +/- 11.5 vs. 387.2 +/- 40.3 pmol cAMP/min/mg protein), while basal and NaF-stimulated activities were quite similar to the activities in normal membranes. These findings suggested a lack of signal transmission between the TSH receptor and the catalytic unit. Incubation of control membranes with TSH and GTP resulted in a synergistic effect on the adenylate cyclase activity. This was not found with the patient's membranes and suggested that the coupling failure was due to a defective guanine nucleotide regulatory protein. We conclude that in this case of type I pseudohypoparathyroidism, the associated mild primary hypothyroidism was due to a partial TSH refractoriness caused by a coupling defect between the TSH receptor and adenylate cyclase. This observation suggests that a common pathogenetic mechanism might underly type I pseudohypoparathyroidism and its associated hypothyroidism.

Adenosine Triphosphate↗
PubMed1980

[Serum IgE in infants. Usual values and values in intolerance to cow's milk proteins (author's transl)].

The usual values of serum IgE were determined by age group (at birth, 3--8 days, 9--45 days, 46--75 days and 76--105 days) in 80 infants under 4 months using the paper-radioimmuno-sorbent test (PRIST). There was a highly significant correlation between these values and the infants' age. Systematic search for specific anti-cow's milk IgE by a related technique (RAST) consistently gave negative results. The same techniques were used in 38 infants with clinical symptoms of intolerance to cow's milk. It would appear that these patients can be divided into two groups according to the presence of absence of extra-digestive symptoms. In the first group, there was a significant increase in total serum IgE, and the RAST was positive in 14 out of 17 patients. In the second group (21 infants), IgE levels were not increased and the RAST was always negative, which suggests that this type of intolerance is not reagin-mediated.

Age Factors↗
PubMed1979

Plasma cyclic nucleotide determination in the investigation of hypocalcemia.

Changes in plasma adenosine 3'5' (cAMP) and guanosine (cGMP) monophosphate, measured by specific radioimmunoassay, after 150 USP/M2 of bovine parathyroid hormone (bPTH) iv administered were studied in children with pseudohypoparathyroidism, and idiopathic hypoparathyroidism, and in normal controls. Basal concentrations of plasma cAMP (17 nmole/1 +/- 1, 6 SEM) and cGMP (8,7 nmole/1 +/- 1, 3 SEM) were the same in all studied children. Plasma cAMP in normal and idiopathic hypoparathyroid children significantly (30-fold, P less than 0.001) and constantly rose with a peak value (537 nmole/1 +/- 210 SEM) observed 5--10 min after bPTH injection. By contrast, no significant change in plasma cAMP occurred in children with pseudohypoparathyroidism. The data confirmed further the unability of pseudohypoparathyroid children to increase cAMP after exogenous PTH, while the cGMP response did not appear to be significantly modified. It is suggested that an injection of 150 USP/m2 bPTH with plasma samples for cAMP assay taken before and 10 min after hormone administration represents a simplified assessment of Ellsworth-Howard's test.

Child↗
PubMed1978

Neonatal parathyroid secretion and renal receptor maturation in premature infants.

16 premature infants with normal trophicity were studied during the 1st week of life using serum parathormone (IPTH) dosage and evaluation of renal tubule maturation by the effect of exogenous parathormone (PTE) on urinary elimination of 3':5'-cyclic adenosine monophosphate (cAMP). As of the 1st day, IPTH levels reached or surpassed those in the adult. Prematurity thus does not appear to influence parathormone response. Given the specificity of the dosage antiserum, it appears reasonable that the PTH detected is biologically active. After PTE, urinary elimination of cAMP does not appreciably increase until the 6th day, while still remaining much lower than adult levels. The lower the weight of the premature infant, the less intense the response of the kidney. It thus seems possible that the later development of renal parathormone receptor in the premature infant may be a factor responsible for neonatal hypocalcemia with hyperphosphatemia.

Body Weight↗