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Biomedical subjects

M Vainsel

Publications and source records attributed to M Vainsel.

At least 19 recordsLinked to original sources
PubMed1995

[Rickets resistant to calcitropic hormones].

Resistance to vitamin D is known since a long time but was erroneously ascribed to phosphate deficiency (phosphate diabetes or deficiency in tubular phosphate reabsorption). True vitamin D resistance can either be due to lack of the receptor itself or to structural abnormality in the hormone -or DNA-binding site of the receptor whereas in a few cases post-receptor resistance has been documented. In view of the therapeutic consequences, diagnosis of vitamin D resistance is needed in every case of rickets not due to simple vitamin D deficiency. Such cases can be easily recognized by normal 25-hydroxyvitamin D concentration in the presence of biochemical, radiological or/and histological signs of rickets.

Drug Resistance↗
PubMed1992

Evaluation of a low-phosphate cow's milk diet on growth and bone mineralization of full-term infants.

Growth, bone mineralization and intestinal absorption were studied in 16 infants fed low-phosphate cow's milk and compared with a group of 15 infants fed conventional cow's milk. In the low-phosphate-fed infants the intestinal calcium absorption was as high as in infants fed human milk, the main characteristics of growth and bone mineralization being similar to those of infants fed conventional cow's milk. Urinary calcium was elevated with a low cAMP excretion. The relative hypercalciuria might be the result of the amount absorbed in excess of that used for the bone accretion.

Animals↗
PubMed1988

[Sequential development of vitamin D metabolites under isoniazid and rifampicin therapy].

A sequential study of 25-hydroxy vitamin D (25-OH-D), 1.25 dihydroxy vitamin D [1.25 (OH)2-D], PTH, alkaline phosphatase and gammaglutamyl transpeptidase (gamma GT) was undertaken in a series of 46 children with asymptomatic tuberculosis treated by isoniazid (INH) alone or associated with rifampin (RMP). These parameters were measured before treatment, 1 month, 3 months after the onset and at the end of treatment (6 months). In order to reduce the influence of the time of the year on the 25-OH-D levels, 22 patients were selected for whom the whole treatment took place between October and May of the following year. In this group, 13 children were treated by INH and RMP, 9 by INH alone. A statistically significant decrease in 25-OH-D levels could be demonstrated after 3 months of treatment in 13 patients under INH and RMP as well as a significant increase in alkaline phosphatase and gamma GT levels. In 9 patients given INH alone, 1.25 (OH)2-D levels decreased after 3 months without significant changes in 25-OH-D, alkaline phosphatase or gamma GT levels. These results emphasize the need for regular biochemical supervision, even if no sign of rickets is observed in these patients.

Adolescent↗
PubMed1985

Carbonic anhydrase II deficiency in 12 families with the autosomal recessive syndrome of osteopetrosis with renal tubular acidosis and cerebral calcification.

Osteopetrosis with renal tubular acidosis and cerebral calcification was identified as a recessively inherited syndrome in 1972. In 1983, we reported a deficiency of carbonic anhydrase II, one of the isozymes of carbonic anhydrase, in three sisters with this disorder. We now describe our study of 18 similarly affected patients with this syndrome in 11 unrelated families of different geographic and ethnic origins. Virtual absence of the carbonic anhydrase II peak on high-performance liquid chromatography, of the esterase and carbon dioxide hydratase activities of carbonic anhydrase II, and of immunoprecipitable isozyme II was demonstrated on extracts of erythrocyte hemolysates from all patients studied. Reduced levels of isozyme II were found in obligate heterozygotes. These observations demonstrate the generality of the findings that we reported earlier in one family and provide further evidence that a deficiency of carbonic anhydrase II is the enzymatic basis for the autosomal recessive syndrome of osteopetrosis with renal tubular acidosis and cerebral calcification. We also summarize the clinical findings in these families, propose mechanisms by which a deficiency of carbonic anhydrase II could produce this metabolic disorder of bone, kidney, and brain, and discuss the clinical evidence for genetic heterogeneity in patients from different kindreds with this inborn error of metabolism.

Acidosis, Renal Tubular↗
PubMed1985

Somatomedin-C in normal puberty and in true precocious puberty before and after treatment with a potent luteinizing hormone-releasing hormone agonist.

To explore further the relationship of gonadal sex steroids to the rise in somatomedin-C (Sm-C) during puberty, we studied a group of children with true precocious puberty before and after treatment which suppressed sex steroid output. Plasma estradiol and testosterone and serum acid-ethanol-extractable Sm-C were determined by specific RIAs in 7 boys and 12 girls with true precocious puberty before and at regular intervals during treatment with a potent LHRH-agonist (LHRH-A), D-Trp6-Pro9-NEt-LHRH. For comparison, Sm-C and sex steroid concentrations were determined in 266 normal adolescents and 37 normal prepubertal children, 1-9 yr of age. The mean +/- SEM Sm-C levels in normal male individuals peaked at 15 yr (2.46 +/- 0.23 U/ml) and at pubertal (genital) stage III (2.29 +/- 0.19 U/ml), and those in normal females reached their highest concentration at 12-15 yr of age and at pubertal (breast) stage III (2.47 +/- 0.15 U/ml). Sm-C concentrations correlated better with pubertal (genital or breast) stage than with chronological age for both sexes and better with testosterone levels in males than with estradiol levels in females. The mean +/- SEM Sm-C concentrations in both males and females with true precocious puberty were 2.07 +/- 0.16 U/ml before therapy and decreased significantly to 1.52 +/- 0.13 U/ml after 6 months of therapy. The mean Sm-C level of the patients remained significantly elevated for chronological age, but decreased into the normal range for bone age after 6-12 months of therapy. Sm-C correlated significantly with testosterone and estradiol levels, but not with growth rate. Mean nighttime GH secretion decreased significantly after 6 months of LHRH-A therapy. In summary, children with true precocious puberty have Sm-C elevations typical of normal puberty. The decrease in Sm-C levels after suppression of gonadal sex steroid output with LHRH-A is evidence that sex steroids are necessary to induce this elevation in Sm-C concentration. The decrease in GH secretion during LHRH-A therapy suggests that the effect of sex steroids on Sm-C levels during normal puberty is mediated, at least in part, through stimulation of GH secretion.

Adolescent↗
PubMed1985

[Periarteritis nodosa in children. Diagnostic difficulties in 2 cases].

Periarteritis nodosa is a rare multisystemic disease whose diagnosis is difficult: diagnostic approach by biopsies in various involved organs is of poor efficacy; abdominal selective angiography yields a precise diagnosis in 50 to 60 of the studied cases as far as the celiac, mesenteric and renal circulations are investigated selectively. Digitalized intravenous angiography (DIVA) carried out in two patients of 9 and 13 years of age allowed to demonstrate aneurysm formations in hepatic, renal and cerebral circulations. Its true efficacy in the diagnosis of periarteritis nodosa of children remains to be determined.

Adolescent↗
PubMed1985

[Course of serum alkaline phosphatase during treatment with isoniazid and rifampicin].

In a population of 132 tuberculous children coming from immigrant families, statistical analysis of data showed a significant increase in serum alkaline phosphatase levels. This phenomenon is more significant when several antibiotics are used (Isoniazid and Rifampicin) than when monotherapy is used (Isoniazid). These results demonstrate a high tendency to occult osteomalacia in tuberculous patients treated by tuberculostatic drugs.

Adolescent↗
PubMed1983

Circulating vitamin D metabolite concentrations in children with nutritional rickets.

Serum calcidiol, calcitriol, and 24,25-dihydroxyvitamin D concentrations were measured in 20 children with vitamin D-deficiency rickets. Vitamin D metabolite concentrations were measured in 17 of 20 patients before treatment and in 14 of 20 patients after vitamin D administration. Conclusions are as follows. (1) Before treatment, serum calcidiol seems to be the best criterion of D deficiency, as it was low (less than 8 ng/ml) in 15 of 17 studied children, whereas calcitriol and 24,25-dihydroxyvitamin D concentrations ranged from undetectable to high values (350 pg/ml and 5.9 ng/ml, respectively). (2) Low calcidiol concentrations may occur despite recent vitamin D intake: low serum values were found in children given vitamin D2 up to two months after the onset of therapy (50 micrograms/day). (3) Elevated calcitriol serum concentrations were observed in all children after initiation of vitamin D therapy; these high concentrations persisted for four weeks or more, even after normalization of serum calcium, phosphorus, and parathyroid hormone values. (4) Healing of biochemical abnormalities can occur even in children with low circulating concentrations of calcidiol and 24,25-dihydroxyvitamin D.

25-Hydroxyvitamin D 2↗
PubMed1979

[Renal acidification disturbance in vitamin D deficiency (author's transl)].

Extensive studies of renal acidification process have been performed in states of vitamin D deficiency. Results show that the process of hydrogen ion excretion is strongly impaired on the entire length of the nephron. Vitamin D and parathyroid hormone probably interfere within tubular cells regulating the concentration of calcium and cyclic AMP; the modification of such an equilibrium carried out by vitamin D deficiency would explain the renal dysfunction.

Bicarbonates↗
PubMed1979

Effect of thyrocalcitonin on renal reabsorption of bicarbonate.

Porcine thyrocalcitonin (TCT) given intramuscularly at a dose of 2-3 MRC units/kg body weight induces a renal bicarbonate wasting probably at the level of the proximal tubule. This effect is found in normal children as well as in patients with renal tubular acidosis and with vitamin D deficiency. The mechanism by which TCT acts on the acidification mechanism is probably independent of parathyroid hormone (PTH) because the effect could also be obtained in hypoparathyroid patients.

Absorption↗
PubMed1977

Oculocraniosomatic neuromuscular disease with hypoparathyroidism.

During a six-year period, an adolescent girl developed a polyglandular disease characterized by hypoparathyroidism, chemical diabetes, growth failure and pubertal delay, hypercholesterolemia, and hypomagnesemia. A slowly progressive neurological disorder occurred simultaneously, consisting of progressive external ophthalmoplegia, mitochondrial myopathy, ataxia, neural deafness, mental subnormality, atypical retinitis, corneal dystrophy, cataract, and increased protein level in the cerebrospinal fluid. An intracardiac conduction defect was also found. This disorder, the cause of which is uncertain, is termed oculocraniosomatic disease. Our patient is apparently unique in that there was an associated hypoparathyroidism.

Adolescent↗
PubMed1976

Urinary excretion of adenosine 3'5' monophosphate in vitamin D deficiency.

Urinary cyclic adenosine 3'5' monophosphate (AMP) excretion has been determined by radioimmunoassay in children with rickets and in control children. Cyclic AMP was greatly increased in children with rickets. The excretion of cyclic AMP correlated significantly with parathyroid hormone levels (PTH) and alkaline phosphatase, but not with age, calcaemia and serum inorganic phosphate. Calcium infusion led to a decrease in the excretion of cyclic AMP. The data are consistent with following hypothesis. During vitamin D deficiency, high PTH levels can increase the renal excretion of cyclic AMP. The effects of PTH on bone resorption fail to maintain the levels of serum calcium due to the lack of vitamin D. The mechanism by which the secondary hyperparathyroidism develops during vitamin D deficiency remains to be investigated.

Alkaline Phosphatase↗