Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0728731 (prematurity)
 7,134 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The influence of a 7 days prematurity, induced by oestrogen or dexamethasone injection to the mothers, on neonatal changes in plasma T4, T3, reverse T3 (rT3), TSH and cortisol levels was studied in 6 full term, 6 oestrogen preterm and 6 dexamethasone preterm lambs. In addition, the pituitary-thyroid axis sensitivity was assessed by the magnitude of the response to TRH administration. At birth, plasma cortisol and T3 levels, as the value of the T3/T4 ratio, were significantly lower in the two groups of preterm lambs than in full term animals; however, whereas plasma T3 concentrations and values of the T3/T4 ratio remained low in oestrogen lambs, they were quickly restored and elevated T3 levels associated to high T4 levels could be even observed in dexamethasone lambs; in this last group, these abrupt changes could be a consequence of raised TSH plasma concentrations recorded at birth. Moreover, if plasma rT3 levels and values of the rT3/T4 ratio were similar during the first hours of life in dexamethasone and full-term lambs, they were significantly higher in oestrogen animals. The responsiveness of the pituitary-thyroid axis to TRH was normal in dexamethasone animals, but was significantly enhanced in oestrogen ones, probably as a consequence of low T3 levels.
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PMID:Pituitary-thyroid axis sensitivity and neonatal changes in plasma iodothyronine, thyreostimulin and cortisol levels in the preterm lamb: comparison of two experimental models. 251 21

RDS continues to be a major problem for premature infants despite a better understanding of its pathophysiology and of ways to try to prevent it. To date, prenatal administration of glucocorticoids has been the most widely used method of accelerating fetal lung development. However, several limitations of this therapy have prompted the search for alternative approaches. Most efforts have focused on the potential use of combined hormonal therapy with glucocorticoids and either thyroid hormones or TRH. The easy transplacental passage of the latter tends to favor its use. The use of hormonal therapy prenatally and surfactant administration at birth appears currently to be the best approach to prevent RDS. The greatest benefit would clearly come from the prevention of prematurity (Fig 1), but this has not proved to be an easy task.
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PMID:Prevention of respiratory distress syndrome. 314 13

Neonatal endocrine status was studied in 14 lambs born 7 days before term, after estrogen injection into the ewes, and in 15 full-term animals. Plasma cortisol and triiodothyronine (T3) levels were depressed during the first hours of life in preterm lambs and plasma reverse T3 levels were significantly higher than in controls. The rise in plasma cortisol levels after Synacthen injection was significantly lowered by prematurity, suggesting reduced sensitivity of the adrenal cortex to ACTH. After ovine TSH injection, plasma thyroxine (T4) levels increased during a shorter period of time in preterm lambs, resulting in a lowered T4 rise; the T3 response was not affected by prematurity. After TRH injection, the rises in plasma T3 and T4 levels were significantly higher in preterm than in full-term lambs, suggesting a pituitary hypersensitivity to TRH linked to prematurity. Moreover it appeared that the response of reverse T3 to TSH or TRH was very weak.
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PMID:Endocrine activity in preterm and full-term lambs. 1. Adrenal response to synacthen. 2. Thyroid response to ovine thyroid-stimulating hormone or thyrotropin-releasing hormone. 392 27