The effect of Mycoplasma arthritidis infection on the kinetics of colloidal carbon clearance in mice.

The activity of phagocytes from A/J mice was estimated by the carbon clearance test following injection of Mycoplasma arthritidis. Phagocytic activity was significantly depressed 12 h post-infection (P = 0.001) and returned to normal values at 24 h. For animals examined 2 and 7 days post-infection, the overall phagocytic activity increased significantly (P < 10(-4). Phagocytic activity gradually decreased and returned to that of the control group by the end of the fourth week. The relative weights of liver and spleen were significantly increased from the 2nd day post infection (P = 0.0028 and P = 0.0014 respectively) and remained increased until the end of the experiment. The early depressive effect on phagocytic activity may be related to superantigen activity with the production of mediators such as macrophage deactivating factor. The later expansion of the macrophage population might bring about the stimulation of autoreactive clones of T and B cells and be responsible for the chronic arthritis that developed in the mycoplasma treated mice.

An epidemiologic survey of thyroid enlargement among schoolchildren in a non-endemic area.

In 534 unselected schoolchildren aged 6-14 yr from the greater Athens area the size of the thyroid gland was assessed by palpation, and information was obtained on sex, age, height, weight, skinfold thickness, socioeconomic class, eye colour and urinary iodine excretion. The results were analysed by discriminant analysis. Altogether 14% of these children had a thyroid enlargement (7% had a definite goitre and another 7% a smaller enlargement). The set of variables studied were significantly discriminatory (Wilk's lambda 0.926, p approximately equal to 0.004). Most of the discrimination was accounted for by height (positive association, b coefficient 0.0114, SE 0.0029, t = 3.95) and weight (negative association, b coefficient 0.0107, SE 0.0030, t = 3.61). No other parameter, including iodine excretion, showed a significant difference between goitrous and nongoitrous. It is concluded that the only genuine difference is that goitrous are heavier for a given height or shorter for a given weight, i.e. more obese. The reason for which obesity protects from sporadic nontoxic goitre is not entirely clear, but probably both nutritional and genetic factors are involved.