Direct immunostaining of TSH receptor related autoantibodies in Graves' disease

Ten thyroid specimens from patients with Graves' disease were investigated immunohistologically with respect to the localisation of thyrotropin (TSH) receptor related autoantibodies. After conventional preparation of formalin-fixed and paraffin-embedded thyroid slices for immunostaining, 3-5 micron tissue sections were incubated with a porcine thyrotropin receptor containing membrane preparation (pTSH-R). The TSH receptor containing membrane fragments bound to the thyroid tissue were revealed with a slightly modified unlabelled PAP technique according to Sternberger, using an antiserum to pTSH-R obtained from immunized rabbits. This technique resulted in a staining of a considerable portion of plasma cells within the lymphoplasmacellular infiltrates of all the Graves thyroids. No staining occurred if for negative control either pTSH-R or its antiserum from rabbit was omitted. In addition, the staining reaction was markedly reduced by pretreatment of pTSH-R with serum from patients with Graves' disease in order to occupy its binding sites for autoantibodies prior to the staining procedure. It is concluded that the staining of the intrathyroidal plasma cells is due to their synthesis of autoantibodies directed against TSH receptor related structures of thyroid epithelia. The results are in keeping with the concept that the thyroid as the target organ itself is the site of autoantibody synthesis in Graves' disease.     

Hypothyreose

An autoimmune thyroiditis represents the main reason of hypothyroidism, defined as a lack of thyroid hormone. This autoimmune process results in destruction of functioning thyroid follicles. While subclinical or latent hypothyroidism is defined on the basis of laboratory values (an elevation of TSH with normal peripheral hormone levels), the typical signs and symptoms are associated with hypothyroidism. In about 80% of cases antibodies against thyroid peroxidase can be measured, but only in about 40–50% of cases antibodies against thyroglobulin are detectable. If hypothyrodism has been diagnosed, substitution with levothyroxine should be initiated, with the therapeutic goal to decrease TSH level to the lower normal range. In cases of subclinical hypothyroidism, levothyroxine medication should be started in patients with a high TSH value, positive antibodies and/or the typical ultrasound of autoimmune thyroiditis. However, substitution with levothyroxine in any case of elevated TSH values should be avoided.     

Accuracy of core temperature measurement in deep hypothermic circulatory arrest

Deep hypothermia is an effective technique for neuroprotection in cardiac surgery. However, standard body temperature measurement may deviate from actual brain temperature. Therefore, we simultaneously measured brain and core temperatures during neurosurgical interventions in hypothermic circulatory arrest to determine its accuracy. Between 1994 and May 2007, 26 patients (12 female, mean age 46+/-14 years), with complex intracranial aneurysms, underwent resection or clipping applying closed chest cardiopulmonary bypass and hypothermic circulatory arrest via inguinal cannulation. During surgery, temperature probes were positioned in the brain, tympanum, bladder, rectum and pulmonary artery. Mean cardiopulmonary bypass time was 147+/-39 min, mean circulatory arrest time was 28+/-8 min. Brain temperatures were best reflected by bladder and tympanum probes (Pearson's correlation coefficients: bladder=0.83; tympanum=0.80; pulmonary artery=0.63; rectum=0.37; P<0.05). Mean deviations from brain temperature were +0.2+/-2.7 degrees C at the tympanum, -0.8+/-2.6 degrees C in the bladder, -0.7+/-2.6 degrees C in the pulmonary artery and -1.8+/-4.4 degrees C in the rectum. In conclusion, temperature monitoring in the bladder and tympanum reliably reflects brain temperature. Temperature measurements in the pulmonary artery and rectum are less optimal.     

Sodium/iodide symporter (NIS) and pendrin are expressed differently in hot and cold nodules of thyroid toxic multinodular goiter.

OBJECTIVE: The expression of two iodide transporters, the sodium/iodide symporter (NIS) and pendrin, was analyzed in thyroid tissues of patients with toxic multinodular goiter (TMNG) and non-toxic multinodular goiter (MNG). METHODS: The levels of NIS and pendrin proteins were analyzed in total protein extracts from nodular and non-nodular tissues by Western blot. RESULTS: In tissue samples from TMNG, we found an increased expression of NIS (2.5-fold) in the hot nodules, and similar levels between cold nodules and non-nodular tissues. In contrast, the levels of pendrin were slightly increased in both hot and cold nodules from TMNG, and decreased (about twofold) in cold nodules from MNG. We also noticed that there was no relationship between NIS and pendrin expression. CONCLUSIONS: Our data demonstrate that hot nodules from TMNG express a higher number of iodide transporters (mainly NIS), whereas cold nodules from TMNG, but not from MNG, show levels of the two proteins comparable with normal tissue, suggesting a role in vivo of TSH in maintaining the expression of NIS and pendrin protein in normal thyroid tissue. Finally, different mechanisms are involved in the regulation of NIS and pendrin expression.     

Generation of intercellular heterogeneity of growth and function in cloned rat thyroid cells (FRTL-5)

The most characteristic hallmarks of human nodular goiters are nodular growth and heterogeneity of structure and function between different areas of the same goiter. In search of the earliest detectable stage of thyroid heterogeneity we have observed doubling times, TSH dependency, and thyroglobulin production in colonies formed from individual FRTL-5 cells growing as monolayers in slide flasks. Single cells and the colonies derived thereof were followed on photographs taken daily until confluence. We observed that each cell had its individual stable multiplication rate throughout the observation period. This was true for all TSH doses tested (0.625-10 mU/ml). A wide range of doubling times (20 h to almost infinite) in the individual cells was observed. The mean growth velocity of subcloned cell lines was highly reproducible in consecutive passages, although a minority of cells escaped this rule. Cells with either high or low thyroglobulin content occurred in clusters, indicating again that specific traits tend to remain stable in the offspring. We conclude that a highly individual growth program, unrelated to mutation, appears to be switched on at the very moment a cell is generated and that this program is passed on to the majority of the offspring, with a minority of cells acquiring qualities differing from those of their sister cell. Therefore, goiter heterogeneity may be the in vivo amplification of a natural phenomenon occurring in all growing cells. Monoclonal adenomas in vivo and nontransformed immortal cell lines in vitro may represent the far end of the large spectrum of individual growth potency among normal thyrocytes.