Charles S. Hollander

Rapid simultaneous radioimmunoassay for triiodothyronine and thyroxine in unextracted serum.

Abstract A three hour radioimmunoassay for the simultaneous measurement of triiodothyronine and thyroxine in 25λ of unextracted serum has been developed. 8-anilino-1-napthalene sulfonic acid has been used to inhibit binding of the two hormones to thyroxine binding globulin. Comparisons of thyroxine with those obtained by competitive protein binding assay and triiodothyronine with those determined by our previously developed radioimmunoassay afford excellent agreement. The speed, accuracy, sensitivity and specificity of this assay renders it highly attractive for routine clinical determinations and for research applications as well.

Receptor-mediated immunomodulation by corticotropin-releasing factor

In both normal and adrenalectomized rats, exogenous corticotropin-releasing factor (CRF) suppresses immune function, and stress-induced immunosuppression can be partially reversed with either CRF antibody or CRF antagonist, suggesting a role for CRF in immunomodulation. We now report binding of CRF to human monocyte-macrophages and T-helper lymphocytes but not to T-suppressor or B lymphocytes. Bound CRF was displaced by synthetic CRF as well as CRF antagonist. CRF binding at these sites was accompanied by increases in the concentration of cAMP (but not cGMP) in the cells, with minimal and maximal effective CRF doses of 10(-13) and 10(-6) M for the monocyte-macrophage and 10(-12) M and 10(-8) M for the T-helper cell. Production of cAMP in response to CRF was effectively inhibited by CRF antagonist in both cell types. Moreover, rat splenocyte proliferation induced by interleukin 2(IL-2; 110 IU) was blocked by CRF, half-maximally at a CRF dose of 2.2 x 10(-10) M and completely at 3.5 x 10(-9) M. Finally, when CRF was added together with a 50-fold molar excess of CRF antagonist the IL-2 effect was fully restored. This demonstration of specific, physiologically relevant CRF receptors on two key immunocytes, the monocyte-macrophage and the T-helper lymphocyte, along with in vitro immunosuppression concomitant with CRF binding reinforces the growing body of evidence for a prominent role for CRF in immunomodulation.

Serum triiodothyronine: measurements in human serum by radioimmunoassay with corroboration by gas-liquid chromatography

Serum triiodothyronine (T(3)) has been measured by radioimmunoassay and corroborated by analysis of the identical samples with a previously described gas-liquid chromatographic technique. Special features of the radioimmunoassay procedure which permit determinations in unextracted serum include the use of a T(3)-free serum preparation for the construction of the standard curve and of tetrachlorothyronine to inhibit binding of T(3) to thyroxine-binding globulin.T(3) values by radioimmunoassay were 138 +/-23 ng/100 ml (mean +/-SD) in 82 normal subjects, 62 +/-9 ng/100 ml in 45 hypothyroid patients, and 494 +/-265 ng/100 ml in 60 patients with toxic diffuse goiter. In the hypothyroid group, the range was similar in patients with both primary and secondary hypothyroidism. There was no overlap between the three thyroidal states. Elevated T(3) levels were seen in 40 cases that appeared clinically hyperthyroid but had normal serum thyroxine (T(3)) determinations, a syndrome we have called T(3) toxicosis. Values obtained with radioimmunoassay agreed closely with those we had previously found by gas-liquid chromatography which were 68 +/-2 ng/100 ml in hypothyroidism, 137 +/-23 ng/100 ml in normal subjects, and 510 +/-131 ng/100 ml in untreated toxic diffuse goiter. Since T(3) is very potent and its level varies in different clinical states, accurate T(3) measurements are required to assess a patients thyroid status properly. The radioimmunoassay for T(3) appears to be sufficiently sensitive, precise, and simple to permit its routine clinical application for this purpose.

The autonomous nodule of the thyroid: correlation of patient age, nodule size and functional status

In light of new techniques for measuring circulating thyroid hormones and for studying the thyroid gland, we present our experience with 35 patients with solitary autonomous nodules of the thyroid to define more precisely the clinical course of patients with this disorder. The patients ranged in age from 19 to 80 years and 31 of the 35 were female. Younger patients were generally euthyroid and sought attention because of a thyroid mass; virtually all older patients were hyperthyroid. Eighteen had obvious clinical features of hyperthyroidism and 5 over age 70 had apathetic hyperthyroidism; all 5 of the elderly and 13 of the 18 under age 70 had elevated thyroxine (T4) and triiodothyronine (T3) levels. Isolated elevation of T3 and elevated basal metabolic rate were observed in 5 previously untreated clinically hyperthyroid young patients. In each of these, thyroid uptake of 131I was not suppressible with exogenous T3 and BMR was elevated in those tested. Two elderly patients, who had previously been treated for conventional hyperthyroidism with radioactive iodine, had T3 toxicosis when hyperthyroidism recurred. There was a strong positive correlation between the age of the patient, the size of the nodule and the thyroid functional state. The mean area of the nodules projected on 131I rectilinear scan for euthyroid patients was 5.1 cm2. The mean area of the nodules in hyperthyroid subjects was significantly higher, 13.4 cm2 in patients with T3 toxicosis and 19.3 cm2 in subjects with conventional hyperthyroidism. Progression from a euthyroid state to hyperthyroidism was observed in four patients. One of these became thyrotoxic within days after an injection of iodinated contrast medium. Spontaneous resolution of nodules occurred in two patients.

Hyperthyroidism after iodinated contrast medium.

INORGANIC iodine administration can precipitate hyperthyroidism in susceptible patients.1 , 2 The patient with an autonomous nodule of the thyroid described below appeared clinically euthyroid desp...

Modulation of pituitary responsiveness to thyrotropin-releasing hormone by triiodothyronine.

The relative roles of triiodothyronine (T(3)) and thyroxine (T(4)) in modulating pituitary responsiveness to thyrotropin-releasing hormone (TRH) have been assessed. (a) 10 hyperthyroid patients with elevated serum T(2) and T(4) levels showed no pituitary response to TRH. After 2 wk of propylthiouracil therapy T(4) levels had fallen to normal in only five patients while T(2) levels were normal in all. Pituitary responsiveness to TRH returned in all patients with normal or high T(4) concentrations. (b) Patients with isolated elevations of serum T(3) (T(3) toxicosis) failed to respond to TRH. TRH responsiveness was restored when T(3) levels fell to normal after propylthiouracil therapy. (c) When pituitary responsiveness to TRH was tested 60 min after a single oral dose of 50 mug of T(3), which increased serum T(3) levels to slightly above the normal range, no rise in thyrotropin (TSH) was seen in six subjects. These findings indicate that T(3) elevations alone can rapidly inhibit pituitary responsiveness to TRH.

The effects of centrally administered neuropeptides on the development of gastric lesions in the rat

Centrally administered neuropeptides were investigated for their effects on the development of gastric lesions in rats. Thyrotropin releasing hormone (TRH), vasoactive intestinal peptide (VIP) and gonadotropin releasing hormone (LHRH) produced gastric lesions acutely, with TRH demonstrating the most pronounced effect in terms of incidence and severity. Ten-fold higher doses of the same peptides administered intravenously produced none or very few gastric lesions. Moreover, pretreatment with atropine partially inhibited their production. Corticotropin releasing factor (CRF) exhibited only mild ulcerogenic effects, and the gastric lesions induced with this peptide developed more slowly than with TRH, VIP and LHRH. Although ulcerogenic in their own right, none of these four neuropeptides significantly potentiated the potent ulcerogenic effects of cold-restraint stress. Since other neuropeptides, including somatostatin, human pancreatic growth hormone releasing factor (hpGRF), substance P, bombesin, and neurotensin, had no demonstrable effects on gastric mucosa, we can conclude that the lesions were not a general effect of intracisternal administration of neuropeptides. The results suggest that within the central nervous system, there are several neuropeptides that play a significant role in the development of gastric lesions via, at least in part, vagal-dependent mechanisms.

HYPERTRIIODOTHYRONINÆMIA AS A PREMONITORY MANIFESTATION OF THYROTOXICOSIS

Abstract Triiodothyronine (T 3 ) levels were raised in four patients from 5 weeks to 9 months before the development of overt hyperthyroidism and before raised serum-thyroxine (T 4 ) levels were found. These observations suggest that hyperthyroid patients may pass through a stage of T 3 toxicosis before developing the usual form of thyrotoxicosis, and that serum-T 3 measurements may be helpful in the early diagnosis of the disease.

Structural characterization and localization of corticotropin-releasing factor in testis

To sequence and thereby definitively characterize corticotropin-releasing factor (CRF)-like material from a representative peripheral tissue, CRF was obtained from 76 ovine testes. The novel extraction procedure involved use of an immunoaffinity column to which a high-affinity CRF monoclonal antibody was attached as well as fast protein liquid chromatography. The complete sequence was elucidated by gas-phase sequencing, carboxyamidopeptidase digestion and cyanogen bromide cleavage. Aside from microheterogeneity at position 39, all the other amino acids were identical to ovine hypothalamic CRF. Additionally, in immunohistochemical studies in the rat, CRF was localized to the Leydig cell. These findings along with related observations by ourselves and others are compatible with the hypothesis that CRF plays a significant local role, possibly by paracrine or autocrine mechanisms.

Regulation of prostaglandin metabolism: inhibition of 15-hydroxyprostaglandin dehydrogenase by thyroid hormones.

15-Hydroxyprostaglandin dehydrogenase has been purified from swine kidney to a specific activity of near 100 miliunits per mg of protein. The purified enzyme was found to be inhibited by thyroid hormone analogues of which triiodothyroacetic acid was the most potent inhibitor. The concentration required for 50% inhibition was 5 μM for triiodothyroacetic acid. The inhibition by thyroid hormones was uncompetitive and non-competitive with regard to NAD+ and prostaglandin E1, respectively. The sensitivity of this enzyme to thyroid hormones suggests that these hormones may regulate the metabolism of prostaglandins in vivo.