Body mass index could be a potential risk factor for periodontitis among healthy young individuals (i.e. those with a body mass index of < 30 kg/m2). It may be useful to include an evaluation of body mass index on a regular basis in university general and oral health examinations.

The effects of TSH on iodothyronine 5- and 5'-deiodinations were investigated using cultured thyroid tissues from patients with Graves' disease. The addition of TSH to the culture medium stimulated all of the iodothyronine-deiodinating activities of thyroid tissues cultured for more than 4 days. Peak TSH-induced activities were found on the fifth day of culture, and increased activities were found up to 9 days. On the fifth day of culture, TSH enhanced both outer and inner ring monodeiodinations in a dose-responsive manner between 62.5 and 250 microU/ml. This stimulation by TSH was blocked by the addition of actinomycin D or propylthiouracil. Incubation of thyroid tissues with (Bu)2cAMP mimicked the action of TSH, and theophylline potentiated the action of TSH. These results suggest that TSH, in an action probably mediated by cAMP, induces synthesis of iodothyronine deiodinases in the thyroid gland.

No abstract

To evaluate the effects of aging on T4 metabolism, serum 3,3'diiodothyronine (3,3'-T2), 3',5'-diiodothyronine (3',5'-T2), and 3,5-diiodothyronine (3,5-T2) as well as T4, T3, and rT3 concentrations were determined by RIAs in 81 normal subjects, aged 24-81 yr. 3,3'-T2, 3',5'-T2, and 3,5-T2 antisera were prepared by immunizing rabbits with the protein conjugate of each diiodothyronine. Since the 3',5'-T2 antiserum cross-reacted with rT3 to the extent of 1.8%, correction was made by subtracting 1.8% of the rT3 value from the measured 3',5'-T2 value. The other 2 antisera had no noticeable cross-reactivity with various thyroid hormone derivatives. Although no significant relation existed between T4 levels and age (r = -0.14; P greater than 0.1) serum T3 showed a significant correlation with age (r = -0.28; P less than 0.05). In contrast, no significant correlation was observed between rT3 and age (r = 0.12; P greater than 0.1). Serum 3,3'-T2, 3',5'-Tw, and 3,5-T2 values (nanograms per dl) all had significant inverse correlations with age, the coefficients of correlation being -0.38 for 3,3'-T2 (P less than 0.01), -0.58 for 3',5'-Tw (P less than 0.01), and -0.47 for 3,5-T2 (P less than 0.01). These findings suggest that sequential monodeiodinating activities in T4 metabolism decrease with increasing age.