Mucosal (secretory) immune system responses to exercise of varying intensity and during overtraining

Athletes are susceptible to upper respiratory tract infection (URTI) during intense training and after major competition; high rates of URTI have also been associated with the overtraining syndrome (staleness). Secretory immunoglobulin A (IgA), the predominant immunoglobulin in mucosal secretion, is a major effector of resistance against pathogenic microorganisms causing URTI. Previous work has shown that salivary IgA levels decrease after a single bout of intense prolonged exercise. The purpose of these studies was to examine the IgA response to various exercise conditions. Whole, unstimulated saliva was obtained before and after exercise. IgA concentration (microgram.mg protein-1) was measured by ELISA and IgA secretion rate (microgram.min-1) calculated. Study 1: Recreational joggers ran on a treadmill for 40 min at 55% and 75% VO2peak and competitive distance runners ran for 90 min at the same intensites. In both groups, IgA secretion rate did not change significantly after exercise at either intensity. Study 2: Competitive runners ran on a treadmill for 90 min at 75% VO2peak on 3 consecutive days. IgA secretion rate decreased 20 to 50% after exercise (p < .001). Post-exercise IgA secretion rates were significantly lower (p < .05) on days 2 and 3 compared with day 1. Study 3: Elite swimmers were followed over a 6 month season, with IgA concentration measured at 5 times. Throughout the season, IgA concentration was significantly (p < .05) lower in stale compared with well-trained swimmers.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of restricting uteroplacental blood flow on concentrations of corticotrophin-releasing hormone, adrenocorticotrophin, cortisol, and prostaglandin E2 in the sheep fetus during late pregnancy

We have examined the effects of reduced uterine blood flow and prolonged fetal hypoxemia on the temporal relationship between changes in hormones associated with the activity of the pituitary-adrenal axis (corticotrophin-releasing hormone (CRH), adrenocorticotrophin (ACTH), cortisol, and prostaglandin E2 (PGE2) in the ovine fetus at 120-125 days of pregnancy, and we sought evidence for placental secretion of CRH and ACTH during prolonged hypoxemia. Uterine blood flow was reduced by placing an adjustable Teflon clamp around the maternal common internal iliac artery to decrease fetal arterial oxygen saturation from mean values of 59.1 +/- 3.3 to 25.7 +/- 4.6% (+/- SEM, n = 10). There was a transient peak in immunoreactive (IR-) CRH at 1-2 h after reducing uterine blood flow. IR-ACTH rose to peak values at +2 h, then gradually decreased to control level by +12 h. Fetal plasma cortisol and PGE2 concentrations were elevated significantly by +2 and +4 h, respectively, and at 20-24 h. The identity of IR-CRH in fetal plasma and in ovine placental extracts was confirmed by HPLC, but there was no consistent umbilical vein--femoral arterial concentration difference for either IR-CRH or IR-ACTH during normoxemia or hypoxemia. We conclude that a sequence of endocrine changes involving CRH, ACTH, PGE2, and cortisol occurs in the fetus during a prolonged reduction in uterine blood flow. However, we did not obtain evidence, for placental secretion of either CRH or ACTH in response to this manipulation.

Stability of teacher temperament ratings over 6 and 12 months

Six and 12-month stability of teacher ratings of temperament was studied in four samples. For the two samples retested after a 6-month interval, the same teacher provided the original and retest ratings. For the two samples retested after a 12-month interval, different teachers provided the retest ratings than provided the original ratings. Four indices of stability were investigated for each sample: cross-rank stability, within-person stability , absolute score stability, and factorial stability. Factorial stability was demonstrated for all samples. For the other three indices of stability, 6-month stability was moderate to high, and significantly higher than the 12-month stability. The general pattern of results is comparable to temperament rating data from parents, with specific coefficients being somewhat higher.