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Biomedical subjects

M S Moukhtar

Publications and source records attributed to M S Moukhtar.

At least 19 recordsLinked to original sources
PubMed1992

Calcitonin gene-related peptide: an autocrine growth factor with regulatory activity in vitro.

We show that an autocrine system for calcitonin gene-related peptide (CGRP) exists in F9 teratocarcinoma cells. Synthesis of CGRP by F9 cells was demonstrated by measuring the peptide concentration in cells and medium and by determining specific mRNA in cells. During six days of culture, CGRP secretion did not vary significantly in the medium, while intracellular CGRP and CGRP mRNA levels increased. F9 cells contained a CGRP-sensitive adenylate cyclase system and CGRP increases the accumulation of cAMP in the culture medium. Interestingly affinity purified antibodies against CGRP specifically inhibited growth of F9 cells by 50%. CGRP therefore stimulates F9 cell growth by an autocrine process, suggesting that CGRP may be a growth factor during early embryogenesis.

Animals↗
PubMed1979

[Tumours markers. Calcitonin and carcinoembryonic antigen in medullary carcinoma of the thyroid (author's transl)].

Medullary carcinoma of the thyroid (MCT) is characterized by high circulating levels of calcitonin (CT) and of carcinoembryonic antigen (CEA), these markers enable the diagnosis of the tumour, the assessment of the efficacy of treatment and the detection of metastases at a subclinical stage. In 130 patients with a primary tumour and/or metastases, CT level was high. In 120 of them (92%), CEA level was also high. There was a positive correlation between levels of CT and of CEA, and both assays should be included in the preoperative examinations. Following removal of the tumour, normalisation of CEA levels takes several weeks, in contrast to CT where normalisation is rapid. Finally, these estimations may be used to detect familial forms at a subclinical stage. This enabled us to detect 16 new cases of MCT amongst 77 subjects studied.

Adrenal Gland Neoplasms↗
PubMed1979

[Immunohistochemical demonstration of calcitonin cells in the fetal thyroid of mice].

Calcitonin was revealed by means of an indirect immunohistochemical method using a serum against synthetic human calcitonin. After the use of the Bouin-Hollande fixative liquid, the hormone was detected in cells located in the central part of the thyroïdian wings. They are few at the 18th day of fetal life, their number increases regularly until reaching ten times the initial number at birth. The immunological reaction is negative if only aldehyde fixatives are used.

Animals↗
PubMed1979

Immunochemical studies on rabbit calcitonin.

Cross reaction studies using radioimmunoassays specific for human and porcine calcitonin showed that rabbit calcitonin is structurally more closely related to human than to porcine calcitonin.

Animals↗
PubMed1979

Acute effects of propranolol and metoprolol on plasma concentrations of parathyroid hormone and calcitonin in uraemic patients.

Nine uraemic patients not yet on dialysis received IV 1 microgram/kg/min of propranolol for 85 min after a priming dose of 1 mg. Fifteen days later six of them received IV 1.2 microgram/kg/min of metoprolol after a priming dose of 1.2 mg. Plasma concentrations of PTH and calcitonin decreased significantly with propranolol but not with metoprolol. No change was observed with either drug as regards plasma concentration of total and ionised Ca and PO4. Heart rate was decreased similarly with both drugs. We conclude that (i) propranolol acutely suppresses PTH and Calcitonin secretion in uraemic patients. This warrants further studies to assess its long term effects on the secretion of these hormones and on renal osteodystrophy; (ii) the contrast between the significant effect of propranolol and the lack of effect with metoprolol supports the concept that PTH and CT secretion are moderated through specific beta 2 receptors.

Adult↗
PubMed1978

[Hypercalcemia and biologically active parathyroid hormone].

Hypercalcaemia always results in serious clinical sequalae and, if not treated, carries a most unfavourable prognosis. The clinician will gain major diagnostic help from an evaluation of the calcitonin and parathyroid hormone blood levels. With regard to parathyroid hormone we have developed, for the first time, a radioimmunoassay which is specific for the estimation of biologically active hormone in the circulation. We are dealing here with an unusual radioimmunological situation as the immunochemical sites are generally quite distinct from those associated with hormonal activity. We are presenting in this first paper the normal values and also the variations that occur in different types of hypercalcaemia. The comparison of these results with those obtained by the usual methods of estimation for parathyroid hormone assay lacking in biological activity shows the value of this new technique.

Calcitonin↗
PubMed1978

Deficiency of calcitonin in age related osteoporoses.

Plasma levels of immunoreactive calcitonin were measured in patients with age-related osteoporosis and with postmenopausal osteoporosis and compared to the levels in control subjects. In all studies immunoreactive calcitonin was lower in the osteoporotic patients. Parathyroid hormone levels were measured in women with postmenopausal osteoporosis and in control women; no difference was observed between the two groups. The results are consistent with the hypothesis that calcitonin but not parathyroid hormone plays a role in postmenopausal and age-related osteoporosis.

Aged↗
PubMed1976

Comparative in vitro biological activity of 1-34 N-terminal synthetic fragments of human parathyroid hormone on bovine and porcine kidney membranes.

1-34 N-terminal fragments of human parathyroid hormone with sequences according to Brewer et al (hPTHB) and to Niall et al (hPTHN) were synthesized and compared for their ability to activate bovine and porcine kidney cortex membrane adenylate cyclase. Results show that these two hormone sequences are able to activate these membranes but at least in this in vitro assay, hPTHN is about 10 times more active than hPTHB on bovine as well as on porcine membranes. These "apparent potencies" with respect to the potency of bPTH 1-34 in bovine and porcine membrane assay systems are respectively 4% and 11% for hPTHB and 39% and 156% for hPTHN. These relative potencies may be interpreted as corresponding to species specificity of the hormone receptor structural relationships.

Adenylyl Cyclases↗
PubMed1975

[Tests of stimulation of calcitonin secretion. Value in medullary cancer of the thyroid].

The detection of high circulating levels of calcitonin is a most valuable procedure to diagnose advanced cases of medullary carcinoma of the thyroid. However, the diagnosis of a primitive tumor in the early stages of development (as in cases of the familial form of the disease) or of a metastasis following ablation of the tumor is more difficult. In the latter cases, the levels of circulating calcitonin may be within normal limits, and for diagnosis one must then resort to tests to stimulate the secretion of calcitonin. We are reporting from our personal experiences the advantages, disadvantages and inconveniences of the three most well-known tests. All patients responded positively to administration of calcium or pentagastrin. The alcohol test, however, produced inconsistent results.

Adult↗