Physical activity and upper respiratory tract infections in a normal population of young men and women: the Amsterdam Growth and Health Study.

A population of young adults, 92 men and 107 women, with a mean age of 21 (+/- 0.7) years, were retrospectively questioned about their habitual physical activity levels (period of 3 months) and the incidence and duration of upper respiratory tract infection (URI) symptoms (period of 6 months). We hypothesized that the incidence and duration of URI symptoms were inversely related with the level of sports activity and total physical activity. Only in women was a statistically significant (P less than 0.05) negative relation found between the incidence of URI symptoms and the level of sports activity. However, the low Spearman's rho coefficient (-0.18) indicates a very weak relation between both parameters.

Habitual physical activity, strenuous exercise, and salivary immunoglobulin A levels in young adults: the Amsterdam Growth and Health Study.

Secretory IgA (S-IgA) levels in stimulated salvia were measured before and after a maximal treadmill test in a population of 175 young adults (84 men, 91 women). Habitual physical activity levels of this population were measured by a standardized interview, and scores were obtained for the amount of time and intensity of sports activities and total activity. Before the maximal treadmill test, men and women showed no statistically significant differences in the salivary concentrations of S-IgA, but the concentration of S-IgA in women decreased and in men increased statistically significantly (P less than 0.05) after the treadmill test. Only women showed a significant correlation between absolute values of S-IgA and the weekly amount of time spent on sports activity measured by a standardized interview expressed in minutes per week.

A seroepidemiological study of amebiasis in Surinam by the enzyme-linked immunosorbent assay (ELISA).

Sera from nine populations in Surinam, South America, were screened for antibodies against Entamoeba histolytica by the enzyme-linked immunosorbent assay (ELISA) technique and a precipitin test (gel diffusion or counterimmunoelectrophoresis). In two small surveys in 1974 and 1978, a high rate of clinically significant ELISA titers was found in a rather isolated group of Amerindians living near the Brazilian border, predominately in the youngest age groups. Amerindians living near the coast showed a low level of seropositivity. Low levels were also found in Bush Negro villages in the interior of Surinam and in Hindustani school children from the savannah area. A high frequency of ELISA titers greater than or equal to 320, indicating a high rate of invasive amebiasis, was detected in persons in a mental institution in Paramaribo. It is concluded that the ELISA, which is much more sensitive than the precipitin tests, is a useful screening test for assessing the prevalence of invasive amebiasis on an epidemiological scale.

Differential potencies of corticosterone and hydrocortisone in immune and immune-related processes in the mouse.

The effects of corticosterone and hydrocortisone on the thymus, the pituitary--adrenal axis, delayed hypersensitivity, the corticosterone plasma level and the numbers of circulating nucleated and monocytic cells were investigated in the mouse. Short-term effects within 48 h after one or two corticoid injections and late effects 7 days after a regimen of 4 corticoid injections were discerned. In short-term experiments hydrocortisone was more active than corticosterone upon the induction of leukopenia and monocytopenia and the inhibition of delayed hypersensitivity. However, regarding late effects and the short-term effect on adrenal weight, corticosterone far exceeded hydrocortisone in activity. Our results could be explained by assuming two feedback-inhibition systems for glycocorticoids. The first, likely to be responsible for the changes observed for the adrenal weight and the numbers of ciruclating white cells after a single glucocorticoid injection, was shown to be expressed in a soluble factor released in the blood stream tentatively designated "glucocorticoid inhibiting factor. The factor was more readily induced by hydrocortisone but displayed a greater specificity in inhibiting effects of corticosterone. The second feedback-inhibition system, responsible for increased numbers of circulating monocytes paralleled by an enhanced delayed hypersensitivity response, was expressed in a decreased corticosterone plasma level, most probably secondary to a diminished release of ACTH from the pituitary gland. With the glucocorticoid doses we used the second feedback-inhibition system was only triggered by the more physiological hormone, corticosterone.