Thyroidology最新文献

Mental retardation caused by congenital deficiency of thyroid hormones can be prevented by early diagnosis and therapy which are assured by neonatal thyroid screening. Congenital hypothyroidism screening is performed in Italy by regional centres which in 1989 have screened more than 82% of neonatal population. Since 1987 a National Register of children affected by CH has been instituted. The results of the analysis of data collected in the first three years are reported.

Growth regulation of the thyroid has been reinvestigated using an ex vivo system of isolated porcine thyroid follicles. Not only the direct effect of TSH, EGF, IGF I as well as iodine on growth of these follicles has been investigated but also the paracrine communication of these follicles with endothelial cells and fibroblasts. The results of recently published investigations with this culture system are summarized in this article. We could demonstrate that IGF I and EGF have a dose related effect on thyroid cell proliferation, whereas TSH has no effect on thyroid cell growth, if the iodine content of follicles is kept normal. Saturation of thyroid follicles with increasing amounts of iodine (1-40 microM K1) inhibit dose dependent EGF, IGF I or fetal calf serum induced thyroid cell proliferation. Inhibition of iodide organification with PTU or MMI abolish the growth inhibitory effect of iodide indicating that an organified iodinated product is responsible for the growth inhibitory effect of iodide on thyroid cell proliferation. Thyroid follicles secrete a FGF like substance which stimulates the growth of fibroblasts as well as endothelial cells. The secretion of FGF into the culture medium is decreased during TSH stimulation and enhanced during stimulation with EGF. The pretreatment of follicles with iodide abolishes the growth promoting effect of conditioned medium from thyroid follicles on fibroblasts and endothelial cells. We conclude that local growth factors like IGF I and EGF are responsible for thyroid cell proliferation whereas TSH stimulates specific function and hypertrophy of thyroid cells.(ABSTRACT TRUNCATED AT 250 WORDS)

The multifactorial nature and complex interactions of regionspecific environmental conditions with host factors in the pathogenesis of endemic goitre constitute a major challenge to the understanding and control of the problem in endemic areas. However, to control and prevent this important public health problem, the most obvious but difficult initial step requires substantial socioeconomic improvements in the affected areas of less developed countries, including, first, provision of efficient iodine prophylaxis programs, second, diversification of dietary constituents with adequate daily protein-calorie intake, and third, institution of proper sanitary conditions with effective water treatment to eliminate organic and bacterial pollutants. This last intervention is also a requirement to control and prevent goitre in the iodine-sufficient more developed countries. In this regard, more research is needed to provide effective ways of water treatment that can be applied in individual households or at the community level.

Following the introduction of echography it has became evident that a large proportion of nodules (15-37%) in euthyroid nodular goiter is entirely or partially cystic (20% in the A. experience). It is thought that cystic areas are subsequent to hemorrhagic necrosis occurring during goitrogenesis and therefore the term "pseudocysts" seems to be preferred. The article summarizes some hypothetical mechanisms of pseudocyst formation. In pseudocysts of recent onset a direct or indirect viral or bacterial etiology is suggested; in longstanding pseudocysts a deficient angiogenesis or immunotoxic mechanisms are proposed.

Several methods have been described to measure immunoglobulins stimulating the growth of thyroid cells in vitro, the so called Thyroid Growth stimulating Immunoglobulins (TGI). The methods make use of either Ig-stimulated guinea pig thyroid (organ) cultures (the cytochemical bioassays; growth is measured via Feulgen-densitometry or pentose shunt analysis), the culture of Ig-stimulated rat or porcine thyroid follicles (growth is measured via 3H-thymidine incorporation), or of Ig-stimulated rat FRTL-5 cells (growth is measured via 3H-thymidine incorporation, or counting the number of mitoses in arrest). The various methods have now been validated: (a) the data obtained with TGI preparations in the Feulgen Cytochemical Bioassay (CBA's) correlate well with those obtained in the FRTL-5 mitosis arrest assay with the same TGI preparations, (b) the growth stimulation can not be ascribed to hormonal contaminations of the used Ig preparations, since protein A-sepharose purified IgG is active in the assays and since anti human IgG's neutralize the growth stimulating effects of the preparations. Using the assays TGI has been found positive in goitrous Graves patients, in sporadic goitre patients and in endemic goitre patients. Particularly, patients complaning of recurrent goitre after thyroidectomy or with recent goitre growth are TGI positive. TGI occurs in sporadic goitre in the absence of TSH-receptor antibodies. The autoimmune-prone animal model of the BB rat also proved to be TGI-positive; the animal shows an increased thyroid glandular weight. Both the histomorphology of human goitres as well as the goitre of the BB rat indicate that the dendritic cell plays a prominent role in initiating the thyroid autoimmune reaction.

Plasma levels of the neuropeptides, vasoactive intestinal polypeptide (VIP, neuropeptide Y (NPY), calcitonin gene-related peptide (CGRP), substance P, and galanin were determined in 15 hyperthyroid patients before and at 3 occassions during 38 weeks of treatment. Treatment was performed with either 131I alone or with carbimazole, with combination of carbimazole and thyroxine, or with subtotal thyroidectomy. Before and after 11 (+/- 4), 24 (+/- 6) and 38 (+/- 5) weeks of treatment, plasma neuropeptide levels were analysed. A group of 9 premenopausal women served as controls. During hyperthyroidism, mean plasma level of CGRP was higher than in controls (P less than 0.001). In contrast, the mean plasma levels of the other measured neuropeptides did not differ from those in the controls. Mean serum level of tree T4 was lowered from 81.9 +/- 30.1 to 23.9 +/- 8.6 pmol/l and mean serum level of free T3 was lowered from 27.3 +/- 7.9 to 6.7 +/- 2.3 pmol/l during the course of the treatment. After 11 weeks of treatment, mean plasma NPY level was significantly increased (P = 0.004) compared to pretreatment levels. However, after 38 weeks of treatment, mean plasma NPY level had returned to control values. The mean plasma CGRP level was significantly reduced at 11 and 38 weeks of treatment compared to pre-treatment value (P = 0.002 and P = 0.004, respectively). Mean plasma level of neurotensin slowly declined during the treatment (P = 0.003). In contrast, mean plasma level of VIP, of substance P, and of galanin did not differ from control value before or after treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

We treated 204 patients with endemic nontoxic goiter with T4, T3 and KI, singly or in combination. Definitely nodular goiters were excluded, since the possibility of autonomy would be increased. Goiter size was evaluated before and 6 months after treatment clinically in a blind way, i.e. the observer (always the same) did not know either the pretreatment goiter size or the treatment the patient had received. At the same time various laboratory parameters were recorded. All the active treatments (but not placebo) resulted in a highly significant decrease in the gland size. The effectiveness decreased in the following order: 1) T3 50 micrograms/d (most effective), 2) (T4 50 micrograms/d + T3 12.5 micrograms) x 2, 3) T4 150 micrograms + iodide 150 micrograms/d, 4) T4 75 micrograms + T3 18.75 micrograms/d, 5) T4 200 micrograms/d, 6) T3 37.5 micrograms/d, 7) Iodide 300 micrograms/d, 8) T4 150 micrograms/d, 9) Iodide 150 micrograms/d (least effective) and 10) Placebo (not effective). The results show that T4 200 micrograms and T3 50 micrograms are roughly equipotent, and slightly more effective than 300 micrograms of Iodide. Taking into consideration the side effects (increase in pulse rate, shortening of the Achilles tendon reflex) did not change the order of effectiveness in an important way. The clinical outcome correlated in general with the suppression of the 131I uptake (r = 0.220, p = 0.03) and the TRH test (r = 0.248, p = 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

In serum of a 70 y. female with Hashimoto's thyroiditis we have identified an M-component IgG which is predominantly composed by a single class of antihuman thyroglobulin antibody. Our assumption is supported by Scatchard analysis and by the high concentration of lambda chains in serum and IgG fraction which are absorbed by h-thyroglobulin. Attempts to dissociate the monoclonal antibody treating the immunoprecipitate at acidic pH, were unsuccessful; only a few percent (3.7) of the antibodies could be released from immunoprecipitate and those were polyclonal. In order to explain the immunoprecipitating reaction of the monoclonal antibody, it is suggested that the antibody is reacting with a repetitive structure of the h-thyroglobulin molecule.

The authors report epidemiological observations about a new endemic goiter area in the North western region of the Centro-African Republic (CAR). The research was carried out in 7 quarters of the chief-town (Bocaranga) and in 8 rural villages; 7621 people were examined by the same three of the present Authors who filled in a sample individual form (proposed by WHO) with the generalities and the goiter grading. The data were analyzed according to sex, age and place of residence by means of the common position parameters and the cumulative frequencies, taking into account the goiter grading of each group. The goiter prevalences observed in the rural areas varied from 70.9% (males) to 82.6% (females), whereas in the chief-town they varied from 29.3% (males) to 57.9% (females). Neurological and myxedematous cretins were seen to constitute 3.4% of the visited population. The M/F goitrous ratio was near unity under the age of 6; above this age, females are more widely and severely affected than males. An important fall in goiter prevalence was observed in adult males after the age of 16. The gradings observed in the rural villages, in both females and males of different ages (0-5; 6-15; 16-45; greater than 45 ys.) were significantly more severe than those observed in the chief town (P less than 0.01). The results obtained confirm those of a preliminary survey which the Authors previously carried out on a sample of school children living in the same region of CAR.

Creatinine clearance, daily urinary protein excretion, serum concentrations of thyroid hormones (TT4, TT3, fT4, fT3), TSH and parathyroid hormone (PTH), have been measured before and after 2 or 6 months of a low protein diet supplemented with aminoacids and ketoanalogues in 18 patients affected by chronic nephrotic syndrome without significant impairment of renal function. Mean creatinine clearance and mean serum protein concentration (79.5 +/- 13.8 ml/min and 5.4 +/- 0.6 g/dl, mean +/- S.D., respectively) did not significantly change (79.1 +/- 17.3 ml/min and 5.5 +/- 0.6 g/dl) after the diet. Mean daily urinary protein excretion (7.1 +/- 2.2 g/day basally) significantly decreased (5.5 +/- 1.9 g/day) after the diet (p less than 0.05). Mean serum TT4 concentration (5.6 +/- 1.8 micrograms/dl basally) significantly increased (6.7 +/- 2 micrograms/dl, p less than 0.05) after the diet. Mean serum TT3 concentration (106.7 +/- 28.5 ng/dl, basally) significantly increased (126.7 +/- 22.6 ng/dl) after the diet (p less than 0.01). Mean serum fT4 and fT3 concentrations (8.0 +/- 2.9 pg/ml and 4.5 +/- 1.6 pg/ml, respectively) did not significantly change (9.4 +/- 2.7 pg/ml, and 4.9 +/- 1.9 pg/ml, respectively) after the diet. In some patients low basal serum concentration values of TT4, TT3, fT4, fT3 became normal after the diet. Mean serum TSH concentration (3.1 +/- 2.3 microU/ml basally), significantly decreased (1.5 +/- 1.3 microU/ml) after the diet (p less than 0.05). Mean serum PTH concentration (0.7 +/- 0.3 ng/ml basally) significantly decreased (0.4 +/- 0.2 ng/ml) after the diet (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)