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Biomedical subjects

R Rappaport

Publications and source records attributed to R Rappaport.

At least 163 records · Page 9Linked to original sources
PubMed1980

[Somatomedin activity and growth hormone secretion in children with idiopathic growth retardation (author's transl)].

Somatomedin activity, as estimated by the porcine bioassay and GH response to stimulation were compared in prepubertal children with severe growth retardation and lack of evidence of pituitary dysfunction. Somatomedin activity was strongly correlated with growth rate. A group of patients had a low somatomedin activity in contrast with normal GH responsiveness. This appears to be a rather frequent situation and deserves further evaluation of the somatomedin system and a more critical approach of GH secretion.

Adolescent↗
PubMed1980

[ADH-deficient diabetes insipidus in children. A study of 93 cases (author's transl)].

Ninety three cases of diabetes insipidus are reviewed after 1 to 20 years follow-up. A codified water deprivation test realized in 50 cases revealed 31 severe cases and 19 partial forms. Apart from surgical causes of diabetes insipidus (16%), tumors represent the most frequent etiology (33.5%), essentially craniopharyngiomas and pinealomas. Histiocytosis X (16%) is also an important cause. In one third no cause could be found. Decreased secretion of anterior pituitary hormones is very common in association with surgical and tumoral causes and can also be found in idiopathic forms. Thus, in our experience, detection of a pituitary deficit is not necessarily associated with a tumor. It can be pointed out that when an etiology is found it is always discovered during the four years following the onset of diabetes insipidus. This implies that very careful neurological and neuroradiological follow-up is necessary during this period.

Adolescent↗
PubMed1979

Diabetes insipidus in children. I. Arginine-vasopressin determination in plasma during short dehydration test.

Plasma vasopressin as well as plasma and urinary osmolality are measured during an overnight dehydration test in vasopressin is undetectable. It is present in plasma from patients with partial diabetes insipidus but the level is not appropriate for plasma osmolality. In patients with polyuria of renal origin plasma vasopressin was significantly higher than in patients with neurogenic diabetes insipidus. Plasma vasopressin measurement is of diagnostic values in partial neurogenic diabetes insipidus and may be of considerable help to distinguish this group of patients from children with polyuria of renal origin.

Adolescent↗
PubMed1979

[Circulating somatomedin activity and growth hormone secretion. Changes during late diagnosed celiac disease and effects of treatment].

Sixteen children, aged 5-19 years with late diagnosed coeliac disease who presented with significant growth delay were studied. Plasma somatomedin was decreased in all patients (mean 0.28 +/- 0.1) but the circulating growth hormone levels were normal in 12 patients. No inhibitory activity could be detected. Somatomedin activity was partially corrected in six patients who were re-examined after 3 months on a gluten free diet. This suggests that low somatomedin levels may be the result of the nutritional abnormalities during the active phase of the disease.

Adolescent↗
PubMed1978

Partial purification, characterization, and assay of a slightly acidic insulin-like peptide (ILAs) from human plasma.

An insulin radioreceptor assay (RRA) using human placental microsomal membranes was used to measure insulin-like activity (ILA) extracted from human plasma concentrates (Cohn fraction IV-4) by acid ethanol. The soluble activity (ILAs), chromatographed on Sephadex G-75 in 1 M acetic acid, migrated as a small molecule (fractional elution volume, 0.56) ahead of insulin (fractional elution volume, 0.70), whereas at neutral pH, ILAs migrated as a large molecular weight species. The ILAs peak from acid gel filtration on Sephadex was further purified by chromatography on carboxymethyl cellulose (CMC). The ILAs peak from both Sephadex and CMC diluted parallel to the porcine insulin standard in the insulin RRA and was totally unreactive in an insulin RIA. The CMC-purified material was iodinated and purified by binding to and elution from human placental membranes. The binding of [125I]ILAs to human placental membranes was inhibited only minimally by insulin and proinsulin and not at all by epidermal growth factor, nerve growth factor, glucagon, or lactogenic hormones, including human growth hormone. Multiplication-stimulating activity (MSA) inhibited in a manner parallel to ILAs. A Scatchard plot of the binding data was nonlinear. Sephadex ILAs was subjected to isoelectric focusing. The fractions assayed in both insulin and ILAs RRAs yielded comparable results. Peaks of ILA were observed at pHs 5.3, 6.6, and 8.4. When CMC-ILA was subjected to isoelectric focusing in polyacrylamide, a single peak of activity migrating between pH 6.2-6.8 was seen. [125I]ILAs focused at exactly the same pH. Electrophoresis of CMC-ILAs in acid-urea revealed a sharp peak of activity migrating with one of the five protein bands seen after staining. Again, [125I]ILAs comigrated with unlabeled ILAs. The molecular weight of ILAs, as determined on a calibrated Sephadex G-150 column at neutral pH, was 9,000-10,000 daltons. CMC-ILAs stimulated [14C]glucose incorporation into triglycerides of rat adipose tissue and augmented [3H]thymidine incorporation into human fibroblasts, chicken embryo fibroblasts, and BALB 3T3 cells as well as [35S]sulfate incorporation into macromolecules of rabbit chondrocyte culture medium. In summary, ILAs isolated on the basis of a RRA for insulin is a slightly acidic peptide with some of the biological activities expected of a somatomedin.

Adipose Tissue↗
PubMed1978

The effect of a slightly acidic somatomedin peptide (ILAs) on the sulphation of proteoglycans from articular and growth plate chondrocytes in culture.

Chondrocyte cultures were prepared from rabbit growth plate (GPC) and articular (ARC) chondrocytes. These two cell types have distinct morphological characteristics. The cells reached maximum numbers by days 10 and 21 for ARC and GPC, respectively. The proteoglycans (PG) contained in the cellular pool were extracted and purified by DEAE cellulose chromatography. The effect of a partially purified somatomedin peptide with insulin-like activity on [35S]sulphate incorporation into PG was evaluated. In both ARC and GPC a significant stimulation of [35S]sulphate uptake into PG subunits was obtained with 1 ng Eq./ml of somatomedin peptide. In order to obtain the same stimulatory effect with porcine insulin, a 1000-fold greater concentration was required. The electrophoretic patterns of the PG subunits on acrylamide-agarose electrophoresis were identical on control incubations and after stimulation with the somatomedin peptide. These data demonstrate in vitro biological activity of this peptide on well differentiated articular and epiphyseal growth plate chondrocytes in culture. These cultures appear to provide a sensitive biological assay for somatomedin peptides.

Animals↗
PubMed1978

[Thyroid involvement in cystinosis].

Thyroid function was assessed in 15 children with cystinosis and it was abnormal in 12. Three of these children were clearly hypothyroid and in the other 9 there were abnormalities of TSH or in the response to TRF. Compensated hypothyroidism is frequent in cystinosis and may be one factor in the severe growth retardation in this condition. The preliminary results of replacement therapy support this hypothesis.

Adolescent↗
PubMed1978

[Culture of normal and pathological human growth cartilage. Action of vitamin D derivatives and somatomedin].

Chondrocytes from normal cartilage of a 2 month old child have been cultured. In vitro the cells maintained their morphological identity and synthesised proteoglycans with electrophoretic properties similar to those synthesised by cartilage in vivo. Sulphation was stimulated by vitamin D metabolites and by somatomedin. This technique has been used to study biopsies of abnormal cartilage.

Cartilage, Articular↗
PubMed1977

Tensiometric studies of cytokinesis in cleaving sand dollar eggs.

Tensions exerted by cleavage furrows of Echinarachnius parma were measured by means of calibrated, flexible glass needles. The tensions exerted by the first and second furrows in isometric contraction were, respectively, 1.58 X 10(-3) dyne (S.D. 0.41 X 10(-3) dyne) and 1.43 X 10(-3) dyne (S.D. 0.44 X 10(-3) dyne). The difference between the two means is not significant. The tensions exerted by the same cleavage furrow at two different lengths, of which the shorter was about 66% the length of the longer, were not significantly different. When the progress of a second cleavage furrow was mechanically blocked, it continued to exert maximum tension up to 9 minutes after its companion blastomere, which served as a time control, completed cleavage.

Animals↗