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C H Emerson

Publications and source records attributed to C H Emerson.

67 records · Page 4Linked to original sources
PubMed1981

Human placenta is an active site of thyroxine and 3,3'5-triiodothyronine tyrosyl ring deiodination.

Human placental homogenate deiodinates the tyrosyl ring of T4 and T3, converting these active thyroid hormones to the inactive iodothyronines, rT3 from T4, and 3,3'-diiodothyronine and 3'-monoiodothyronine from T3. The conversion of T4 or rT3 is time, temperature, pH, and protein content dependent and does not occur in the absence of the thiol-regenerating agent dithiothreitol. Phenolic ring deiodination of T4, T3, and rT3 was not detected. Failure of the transplacental passage of T4 and T3 from mother to fetus may be secondary to the placental tyrosyl ring deiodination of these iodothyronines.

Diiodothyronines↗
PubMed1981

Human cord blood concentrations of thyrotropin, thyroglobulin, and iodothyronines after maternal administration of thyrotropin-releasing hormone.

TRH or saline was administered to 214 term pregnant women at various time intervals (8-820 min) before delivery. Cord blood (CB) was obtained, and plasma TSH, T4, T3, rT3, and thyroglobulin concentrations were measured by specific RIA. CB TSH was significantly elevated within 20 min after TRH administration and remained elevated for 180 min. CB T3 rose significantly by 60 min and remained elevated for 820 min. CB T4 was significantly increased from 120 to 820 min after TRH administration. There was no significant change in the CB thyroglobulin concentration. These findings demonstrate for the first time that TRH crosses the human placenta, that the fetal pituitary is responsive to TRH, and that endogenous TSH stimulates the fetal thyroid.

Female↗
PubMed1980

Evidence for the presence of the putative TRH metabolite, deamido-TRH, in human urine.

Using a specific radioimmunoassay (RIA) for deamido TRH (TRH-OH), TRH-OH immunoreactivity (IR) was detected in the urine of 54% of a group of normal subjects and patients with thyroid disease. Human urine TRH-OH IR eluted in the position of synthetic TRH-OH on Sephadex G-10 gel filtration (GF). In contrast, urine TRH IR, as determined by a specific TRH RIA, did not elute with synthetic TRH. HU-TRH was prepared for studies on its crossreactivity in the TRH-OH RIA. HU-TRH is the term given to a previously described substance(s) which is obtained from human urine by immunoabsorption to anti-TRH antiserum, is reactive in the TRH RIA, and shows non-identity with synthetic TRH on GF. HU-TRH was not reactive in the TRH-OH RIA. These studies suggest that the putative TRH metabolite, deamido TRH, is present in human urine and that HU-TRH is neither TRH-OH or as closely related structurally to TRH-OH as it is to TRH.

Chromatography, Gel↗
PubMed1979

Lack of evidence for thyrotropin-releasing hormone deamidation in normal and hyperthyroid human sera.

Two-hour incubations of human serum with 50 ng TRH or pyroglutamyl-histidyl-proline (TRH-OH) were performed under substrate conditions of 0.2 microgram substrate/ml serum. During incubations with normal serum, 46.3 +/- 1.3 (SEM) ng TRH were degraded while only 14.2 +/- 5.1 ng TRH-OH were degraded (P less than 0.001). During incubations with serum from patients with hyperthyroidism, 42.7 +/- 2.6 ng TRH were degraded compared to only 19.6 +/- 2.0 ng TRH-OH (P less than 0.001). Despite the fact that TRH degradation was significantly greater than TRH-OH degradation in both normal and hyperthyroid serum, no formation of TRH-OH (less than 3.1 ng/incubation tube) from TRH was detected. Formation of TRH-OH from TRH was also not noted when normal or hyperthyroid serum was incubated with TRH at substrate concentrations of 62.5 microgram/ml serum. These data confirm other reports that TRH deamidation does not occur in normal serum and extends this observation to hyperthyroid serum.

Humans↗
PubMed1975

Plasma thyrotropin-releasing hormone concentrations in the rat. Effect of thyroid excess and deficiency and cold exposure.

To investigate the physiology of thyrotropin-releasing hormone (TRH) secretion from hypothalamus and brain, a method for measurement of peripheral plasma TRH concentrations in rats was developed. Blood was collected in heparin and dimercaptopropanol containing [3H]TRH to determine recovery. The plasma was extracted with methanol and the redissolved dried methanol extracts applied to anti-TRH Sepharose columns. These columns bound greater than 80% of 125I-TRH applied and had a capacity in excess of 20 ng TRH. TRH was eluted from the anti-TRH Sepharose with acetic acid and quantitated by radioimmunoassay of the lyophilized acetic acid eluate. Mean recovery of unlabeled TRH was 44.7+/-6.1% (SD) and mean recovery of [3H]TRH was 44.0+/-4.0%. Mean plasma TRH concentrations, corrected for recovery, in plasma pools from eight groups of normal male rats (four to seven pools/experiment, five to seven rats/pool) ranged from 7 to 30 pg/ml (mean, 16). In experiments in which rats were given 5, 10, 15, 0r 50 mug thyroxine daily for 1 wk or in thyroidectomized rats, mean plasma TRH concentrations did not differ significantly from those of control animals sacrificed at the same time. In each experiment, four to seven plasma pools, each from five to seven rats, were processed from both control and experimental groups. No changes in plasma TRH concentrations were found in rats exposed to cold (4degreeC) for 30, 60, and 90-180 min. Signigicant increases in plasma thyrotropin (TSH) concentrations were found in all cold-exposed animals. These results provide no evidence that thyroid hormone excess of deficiency affects TRH secretion. If TRH secretion is responsible for cold-induced increases in plasma TSH concentrations, the increase in TRH secretion is of insufficient magnitude to alter periperal plasma TRH concentrations.

Animals↗