Autoantibodies blocking the TSH-dependent production of cAMP in thyroid cells (TSH-BAb) have been described in atrophic thyroiditis (AT; idiopathic myxedema) and in neonates with transient hypothyroidism, but their incidence in autoimmune thyroiditis in relation to thyroid status remains to be completely established. To this purpose TSH-BAb were evaluated in a group of 140 consecutive patients with autoimmune thyroiditis, which included 26 cases of AT and 114 subjects with goitrous Hashimoto's thyroiditis (HT); among the goitrous group 27 were euthyroid (HT-E), 32 had subclinical hypothyroidism (HT-SH), and 55 had clinical hypothyroidism (HT-H). TSH-BAb were measured in immunoglobulin G prepared by DEAE-Sephadex A-50 by determining their ability to inhibit TSH-dependent cAMP production in a differentiated strain of cultured rat thyroid cells (FRTL-5). Using this sensitive and reproducible method, TSH-BAb were detected in 12 of 26 (46%) patients with AT, in 1 of 27 (3.7%) subjects with HT-E, in 3 of 32 (9.4%) with HT-SH, and in 20 of 55 (36%) with HT-H. The prevalence of TSH-BAb was higher in AT vs. HT-H (P less than 0.001), HT-SH (P less than 0.001), or HT-E (P less than 0.001), and in HT-H vs. HT-SH (P less than 0.001) or HT-E (P less than 0.001). Mean TSH-BAb levels in AT were higher than those in HT-H (P less than 0.005) and HT-SH (P less than 0.025); the difference was not significant between HT-H and HT-SH. An inverse correlation was found between TSH-BAb levels and estimated goiter weight (P less than 0.005). The results of the present study indicate that 1) in autoimmune thyroiditis TSH-BAb are detectable almost exclusively in hypothyroid patients, their prevalence being higher in overt hypothyroidism than in subclinical thyroid failure; 2) the prevalence of TSH-BAb and their mean levels are higher in hypothyroid patients with AT than in those with HT; and 3) therefore, the presence of circulating TSH-BAb appears to be related to the development of hypothyroidism and thyroid atrophy.

The outcome of L-thyroxine (L-T4) replacement therapy in children with congenital hypothyroidism (CH) remains to be completely evaluated. In this paper the overall pattern of response to L-T4 replacement therapy was studied in a group of 19 children with CH diagnosed by neonatal screening (10 with hypoplastic/aplastic thyroid disease, group H/A; 9 with gland ectopy, group E) who were followed-up for 60 +/- 27 months (mean +/- SD). With 1 exception serum T4 at diagnosis was greater than 2 micrograms/dl in children of group E and less than 2 micrograms/dl in those of group H/A. The initial dose of L-T4 (8-10 micrograms/kg BW/day) was modified in relation to age and weight in order to maintain serum TSH less than or equal to 5 microU/ml and FT3 in the normal range. A general inverse correlation between serum TSH and FT4 or FT3 concentrations was found, and the mean levels of serum FT4 and FT3 were significantly higher according to the following order of TSH results: low TSH (0-0.5 microU/ml) greater than normal (greater than 0.5-5 microU/ml) greater than elevated TSH (greater than 5 microU/ml). TSH levels less than or equal to 5 microU/ml were associated with FT4 values in the upper half of the normal range (54% of observations) or even higher (46%). Elevation of serum FT4 alone with FT3 values in the normal range did not result in clinical thyrotoxicosis, alteration of growth or premature craniosynostosis.(ABSTRACT TRUNCATED AT 250 WORDS)

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The results of free thyroxine (FT4) measurements in dried blood spots on filter paper in 744 euthyroid newborns (616 at term, 128 preterm), 10 newborns with congenital hypothyroidism and 4 euthyroid newborns with congenital TBG deficiency are reported. FT4 was measured by column adsorption chromatography of free hormone followed by radioimmunoassay in the eluate. FT4 values averaged 24 +/- 0.2 pmol/L (mean +/- SE) in euthyroid newborns, 23.0 +/- 0.9 pmol/L in euthyroid newborns with TBG deficiency (p = NS), and 5.7 +/- 0.4 pmol/L in hypothyroid newborns (p less than 0.001 vs both groups). Total T4 (TT4) values in newborns with TBG deficiency were not different from those in hypothyroid newborns, but were significantly lower than those in euthyroid newborns without TBG abnormalities. FT4 values were higher in full-term newborns than in preterm newborns (25.2 +/- 0.3 vs 21.2 +/- 0.5 pmol/L, p less than 0.001). In both full-term and preterm newborns FT4 values in dried blood spots increased with birth body weight (bbw), virtually plateauing when bbw was greater than 2,500 g. The cut-off values established on the basis of the bbw (8.0 and 13.1 pmol/L for a bbw of less than or equal to 2,500 g and greater than 2,500 g, respectively) showed higher specificity and predictive value of positive results than the cut-off values based on the gestational age. In any case, the sensitivity, specificity and predictive values of FT4 determinations proved to be higher than those of TT4 and TSH measurements.(ABSTRACT TRUNCATED AT 250 WORDS)

Films from blends of hyaluronic acid with poly(vinyl alcohol) and with ethylene-vinyl alcohol copolymers were prepared from solutions in water and dimethylsulfoxide by a casting method. The study of the interactions between the natural and synthetic component has been carried out through thermal and morphological analysis. The results show that the crystallinity of poly(vinyl alcohol) and its copolymers decreases with increasing hyaluronic acid content and these crystallizable polymers exhibit no tendency to crystallize when hyaluronic acid content is more than 80 wt%. The relatively good miscibility in these blends may be due to the capacity of the natural and synthetic component, each with abundant hydroxyl groups, to interact mutually through hydrogen bonding. The presence of such interactions was supported by the observation of the melting point depression of the synthetic component in thermal analysis of the blends. Melting point depression was more accentuated in melt recrystallized blends. These results suggest that the interactions between the two polymers are enhanced if the blends are brought close to the melting point of the synthetic component. Films from blends of hyaluronic acid with poly(vinyl alcohol) and with ethylene-vinyl alcohol copolymers were prepared from solutions in water and dimethylsulfoxide by a casting method. The study of the interactions between the natural and synthetic component has been carried out through thermal and morphological analysis. The results show that the crystallinity of poly(vinyl alcohol) and its copolymers decreases with increasing hyaluronic acid content and these crystallizable polymers exhibit no tendency to crystallize when hyaluronic acid content is more than 80 wt%. The relatively good miscibility in these blends may be due to the capacity of the natural and synthetic component, each with abundant hydroxyl groups, to interact mutually through hydrogen bonding. The presence of such interactions was supported by the observation of the melting point depression of the synthetic component in thermal analysis of the blends. Melting point depression was more accentuated in melt recrystallized blends. These results suggest that the interactions between the two polymers are enhanced if the blends are brought close to the melting point of the synthetic component