TSH stimulation of adenylate cyclase (AC) and iodine uptake was compared in 39 surgical specimens of primary tumours and/or lymph node metastases from 29 human differentiated thyroid carcinomas. TSH stimulation of AC was significantly lower (2.1 \ m=+-\0.3 fold the basal level) in patients without in vivo 131I uptake than in patients with 131I uptake (4.7 \m=+-\ 0.8). A significant correlation between TSH responsiveness of AC and TSH stimulation of in vitro 125I uptake was found. There was also a relationship between 127I tissue content and AC responsiveness. Nevertheless analysis of individual data showed discrepancies in about one quarter of the cases. Thus the response of neoplastic cell membrane to TSH appears to be necessary for iodine metabolism, but it is not sufficient. Additional defects may in some cases explain the lack of either iodine uptake or organification.There is a general correlation between TSH stimulation of AC and histological type. However, data from papillary carcinomas with various degrees of uptake capacity show that TSH stimulation of AC correlates better with functional activity than with cell morphology or tissue architecture.Stimulation by GMP P(N)P was decreased in carcinomas, while NaF stimulation was not significantly different from normal. This suggests that alterations in thyroid cancer are more related to defects in the regulatory than in the catalytic subunit of AC.
Human thyroglobulin (Tg) was used as an antigen in the development of antibodies by the hybridoma technique. From four antibodies that bound more than 40% labeled Tg, two were characterized (182/E4 and 211/A5). They were both of the immunoglobulin G 2ab subclass, and provided an affinity constants (Ka) of 1.2 X 10(10) and 7.7 X 10(9) mol-1, respectively. The specificity of these antibodies was demonstrated by the absence of cross-reaction by monoiodothyronine, diiodothyronine, T3, T4, and sialic acid. A RIA was developed with 182/E4 or 211/A5, and the least detectable dose, based on the standard curve, was 10 ng/ml. The immunoreactivities of 182/E4 and 211/A5 to four Tg preparations different in iodine content appeared to be identical. Histochemical staining was used on normal and neoplastic tissues with both antibodies. Positive reactions were obtained in both cells and colloid, with heterogeneous staining from one follicle to another. Papillary carcinoma showed numerous positive cells, in contrast with Hürtle cell tumors which displayed very few positive cells. Anaplasic giant and spindle cells were negative. Monoclonal antibodies to human Tg are useful for in vitro detection of Tg.
The distribution of iodotyrosines and iodothyronines has been studied in poorly iodinated 19 S thyroglobulins isolated by sucrose gradient centrifugation from five human thyroid tissue. The 19 S thyroglobulins have been fractionated by isopycnic centrifugation in 34.5 % rubidium chloride gradient. The distribution of iodoamino acids depends on the total iodine content of each fraction. The variations in MIT1) and DIT residues with
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