Biomedical subjects

S Reichlin

Publications and source records attributed to S Reichlin.

At least 199 records · Page 11Linked to original sources

PubMed1975

Measurement of plasma and tissue triiodothyronine concentration in the rat by radioimmunoassay.

This paper reports a radioimmunoassay method for triiodothyronine (T3) and the application of this assay to the study of plasma and tissue T3 concentration in the rat. Several antisera formed to a T3-bovine fibrogen complex in guinea pigs and T3-thyroglobulin complex in rabbits are shown to have low or no cross reactivity with T4, monoiodotyrosine, diiodotyrosine, tetraiodothyroacetic acid (TETRAC) and reverse T3. Cross reactivity with T3 derivatives, triiodothyroacetic acid (TRIAC), and triiodothyropropionic (TRIPROP) was variable, some antisera differentiating moderately well and others not at all. An extraction method is described which removes approximately 85% of added 125I-T3 or unlabelled T3 from tissues and in the final step represents 57% of total tissue T3. Mean plasma T3 in 5 normal male rats was 58 plus or minus 6.0 ng/100 ml (SEM), in liver 769 plus or minus 56 ng/100 g, and kidney 627 plus or minus 39 ng/100 g. Tissue to plasma concentration gradients for liver and kidney were 13.3 and 10.8, respectively.

Animals↗

PubMed1975

Natural history of the familial medullary thyroid carcinoma-pheochromocytoma syndrome and the identification of preneoplastic stages by screening studies: a five-year report.

1. In the fifth year of followup, 8 of 12 original patients thyroidectomized for MTC, diagnosed solely by abnormal calcitonin values, are disease free by all criteria. Elevated calcitonin levels are the only manifestation of active disease in three patients with presumed metastases. 2. Routine annual screening of susceptible individuals is a practical measure and has in 6 cases detected the premalignant condition of G-cell hyperplasia and in 1 patient a premetastatic state of MTC. It is premature to conclude that yearly screening is sufficient to detect all cases of premetastatic disease and for this reason we are recommending a yearly screen with pentagastrin and calcium tests and the more convenient pentagastrin test at 6 month intervals for those in the high-risk age group between 8 and 18. If screening at such intervals proves to be ineffective in preventing the disease in every case, consideration must be given to prophylactic thyroidectomy although we are not currently recommending this precedure. 3. Pentagastrin injection is often a more effective secretagogue for calcitonin than is calcium infusion, but this is not uniformly true. We therefore recommend use of both tests as the most appropriate screening procedure. 4. Epinephrine is a major secretory product of pheochromocytomas in the J-kindred and sequential E/N ratios may be of use in the early detection of pheochromocytoma in other kindreds. 5. Adrenal medullary hyperplasia has been found in 3 adrenal glands and is probably a preneoplastic condition analogous to C-cell hyperplasia.

Adolescent↗

PubMed1975

Regulation of the hypophysiotropic secretions of the brain.

Two elements govern the secretion of the anterior pituitary. One influence, from the hypothalamus is mediated by the hypothalamic hypophysiotrophic hormones, which are elaborated in specialized neurones and reach the pituitary by way of the hypophysial-portal vessels. The other influence is the feedback control exerted by target gland hormones directly on the pituitary, and possibly on the hypothalamus as well. In the case of the pituitary-thyroid axis, thyroid hormone exerts a direct inhibitory effect on TSH secretion, interacting with the stimulatory effects of thryotrophin releasing hormone (TRH). In the rat, TRH excretion in the urine is reduced by thyroid deficiency, suggesting that the thyroid hormones may also be involved in regulating TRH secretion, but we cannot be certain that the effect is on hypothalamic TRH secretion, since TRH also is found in other parts of the brain. In the case of pituitary-goned control, estrogens inhibit pituitary responsiveness to luteinizing hormone releasing hormone (LRH) in men, but sensitize the pituitary in women. In men, estrogens stimulate LRH release as inferred from changes in plasma bioassayable luteinizing hormone-releasing factor (LRF) activity, thus suggesting a positive feedback effect of estrogens on the hypothalamus. In women, LRF activity appears in the blood during midcycle, suggesting that mid-cycle LRH secretion, together with estrogen sensitization of the pituitary, are components of the mechanism underlying the midcycle ovulatory surge.

Animals↗

PubMed1974