In vivo and in vitro regulation of thyroid leukemia inhibitory factor (LIF): marker of hypothyroidism.

Several cytokines regulate thyroid function and may be involved in the pathogenesis of thyroid disorders, including euthyroid sick syndrome. Leukemia inhibitory factor (LIF), a neuroimmune pleiotropic cytokine, was measured to assess its role in hypothalamic-pituitary-thyroid function. Mean circulating serum LIF levels in 10 hypothyroid patients [TSH, 23+/-0.

Measurement of leukemia inhibitory factor in biological fluids by radioimmunoassay.

Leukemia inhibitory factor (LIF) exhibits multiple biological activities in various tissues, and we have shown that LIF activates POMC gene transcription in response to immune signals. As higher serum levels of LIF have been reported in septicemia, we measured LIF values in biological fluids by RIA. Immunoreactive LIF was detected in 303 of 428 human serum samples.

Four rapid serum-urine combination assays of choriogonadotropin (hCG) compared and assessed for their utility in quantitative determinations of hCG.

We evaluated the performance of four visually read pregnancy tests (TestPack Plus hCG Combo, ICON II hCG, SureCell hCG-Serum/Urine and PregnaGen 1-Step) designed to detect increased concentrations of choriogonadotropin (hCG) in either serum or urine samples. The biochemical sensitivities and specificity in both serum and urine samples were similar for each kit. All kits correctly identified pregnancy serum samples: The TestPack Plus hCG Combo and SureCell hCG-Serum/Urine were 100% specific; the other two kits exhibited a few false-positive results.

The beta-core fragment of chorionic gonadotropin is not complexed to macromolecules in amniotic fluid.

A prior report claimed that amniotic fluid contains substantial quantities of beta-core fragment, a major degradation product of CG metabolism, complexed to macromolecules. In an attempt to confirm this finding, we measured beta-core fragment concentrations in 36 second- and 22 third-trimester amniotic fluid samples in a direct beta-core fragment RIA as well as a total CG RIA and found that all of the apparent immunoreactivity could be accounted for by the cross-reaction of CG and CG beta in the beta-core fragment RIA. Chromatography of concentrated pools of amniotic fluid or pregnancy serum failed to reveal a peak of CG immunoreactivity in the beta-core fragment elution area.