Acta endocrinologica. Supplementum最新文献

The molecular cloning of certain antigens to thyroid autoantibodies present in patients with autoimmune thyroid disease would be of great value in further understanding the pathogenesis of these diseases, and in devising new approaches for their treatment. The ideal method for molecular cloning is to first obtain a partial amino acid sequence of a purified protein and to construct an oligonucleotide probe for screening an appropriate cDNA library. Unfortunately in the case if thyroid autoimmunity, important antigens such as the TSH receptor and the microsomal antigen have not been purified. An alternate approach devised by Young & Davis (1983) is to construct a cDNA library in a vector that expresses the encoded proteins. The library can then be screened with an antibody as a probe. We have constructed cDNA libraries in gt11 using mRNA purified from human, pig and rat thyroid cells. Our experiences in constructing and screening these libraries will be described. The advantages of this system are 1) the protein does not have to be purified, 2) previously unknown antigens may be identified. The disadvantages are 1) lack of specificity with antibody selection, 2) because the cDNA is inserted in the beta-galactosidase gene in the vector the antigen is expressed as a fusion protein. This may disturb the tertiary structure of the antigen and alter its antigenicity, 3) cDNA inserts frequently only contain part of the antigen molecule, and may therefore lack important epitopes; polyclonal antibody may therefore be preferable to monoclonal, 4) only 1 in 6 cDNA inserts will be in the correct reading frame for antigen expression, 5) the expressed protein is not glycosylated.(ABSTRACT TRUNCATED AT 250 WORDS)

Thyroid growth-stimulating immunoglobulins are responsible for goitre formation not only in Graves' and Hashimoto's disease but also (partly) in simple goitre, especially in recurrent cases. TGI are antibodies, the TSH receptor, however, appears not to be the antigenic site in simple goitre. In our own studies two TGI assay systems ([3H]thymidine incorporation into isolated porcine thyroid follicles and into FRTL-5 cells) gave comparable results. TGI was found in 20 out of 72 patients with simple goitre (27%) coming from an endemic goitre area (biased by selection, i.e. certainly including sporadic forms) and in 10 out of 26 patients (38%) with recurrent goitre. TGI levels were higher in thyroidal venous blood compared to cubital blood (simultaneously drawn during surgery) indicating an intrathyroidal production of TGI. Thyroid growth-blocking antibodies as estimated in the FRTL-5 cell assay in one of our patients might be of significance not only in primary myxoedema but also for congenital hypothyroidism.

Autoantibodies (aAb) in serum of patients with autoimmune thyroid diseases (AITD) are directed to an antigen associated with thyroid microsomes. Although it has been investigated over almost three decades, the nature of this autoantigen remained unknown. Taking advantage of monoclonal antibodies (mAb) produced in our laboratory, we have demonstrated that thyroid peroxidase (TPO) is the 'microsomal' antigen. Sera of patients with AITD strongly inhibited the binding of only one of 19 mAb raised against human thyroid plasma membranes. This mAb did not react with thyroglobulin but achieved significant binding to preparations of human, bovine and porcine TPO, bovine lactoperoxidase and human myeloperoxidase without altering the enzyme activity. The mAb has been used to immunopurify the human TPO from solubilized thyroid microsomes. The procedure allowed high purification (approximately 3500-fold) of the native enzyme with a reasonable yield (approximately 10 mg TPO/kg thyroid tissue). Human TPO exhibited a specific activity of 350-400 guaiacol U/mg, a peak in the Soret region and a ratio of A411 nm to A280 nm of 0.20-0.25. Upon SDS-polyacrylamide gel electrophoresis, the purified enzyme gave two contiguous bands in the 100 kDa region. Performed in non-reducing conditions, electrophoresis of TPO showed one band in the same 100 kDa region. Sera with aAb to the microsomal antigen immunoprecipitated purified TPO to an extent ranging from 80 to 100% of the initial enzyme amount while sera from normal subjects or from patients with undectable level of anti-microsomal aAb elicit a decrease of less than 30% of the total TPO activity.(ABSTRACT TRUNCATED AT 250 WORDS)

In primary culture porcine cells form polarized cell layers. We have designed culture conditions in which we can have access to only one side of the cell layer, either the apical or the basal surface. In addition, using culture chambers with permeable bottom we can have access to either side of the cell layer which separates two compartments. Using these organized systems we have shown that the iodide concentrating mechanism and the TSH-receptor adenyl cyclase complex are localized on the basolateral domain of the thyroid cell plasma membrane. We also demonstrated the existence on the apical surface of an amiloride sensitive sodium uptake. Finally we observed that about 10% of newly synthesized thyroglobulin appears to be secreted directly into the basal compartment, 90% being secreted in the apical compartment.

Ten diabetic teenagers were admitted into our hospital for two nights, separated by one week. In a double-blind cross-over randomized study they received either 50 micrograms of the new long-acting somatostatin analogue Sandostatin sc or placebo. All patients were between 12 and 16 years of age, C-peptide negative with a duration of diabetes of at least four years. They had either conventional therapy or insulin pump therapy. Insulin doses and diets were kept unchanged. Blood samples were taken half hourly from 17.00 h until 09.30 h the next morning from an indwelling venous catheter. Hormonal and metabolic profiles on the two nights were evaluated by means of a distribution free time sequential co-movement analysis and by the paired Wilcoxon's signed rank test. After Sandostatin was given at 22.00 h, GH levels were significantly suppressed during 4 h. During that period blood glucose was slightly but significantly lower than after placebo. The free-insulin profiles from both nights were very comparable. Co-movement analysis showed a significant correlation between glucose and free insulin variations with a 30-min backward shift of the glucose curve. However, after Sandostatin administration this relation was lost in the period between 22.00 and 07.00 h, indicating a different effect of insulin on glucose levels during the nights Sandostatin was given. Early morning glucose rises were associated with free insulin levels below 20 mU/l. This association was not altered during the Sandostatin nights. Glucagon was not suppressed by Sandostatin except at 120 min after injection, and remained unchanged during the rest of the observation period.(ABSTRACT TRUNCATED AT 250 WORDS)

The review presents a concept for the pathogenesis of spontaneous, organ-specific autoimmune diseases that take into account an altered immune regulation, modulating hormonal influences and a genetically determined primary susceptibility of the target organ for the autoimmune attack. The concept is exemplified by means of the Obese strain (OS) chicken model which develops a spontaneous hereditary autoimmune thyroiditis. In respect to the the altered function of the immune system both, MHC associated (Ir) and non-MHC associated genes are involved. The MHC, i.e. a certain haplotype, only plays a modulatory role in determining the frequency and severity of spontaneous autoimmune thyroiditis, while the presence of certain non-MHC associated genes is a absolute prerequisite for the emergence of the disease. The latter is also true for the genetically determined target organ susceptibility, while hormonal factors, notably sex-steroids and glucocorticoids, again only have a facultative, modulatory effect. Only if an appropriate genetic constellation concerning the non-MHC encoded aberrant immunological function and genes coding for the susceptibility of the thyroid gland for the autoimmune process is present, severe autoimmune thyroids develops.