Effects of anaerobic exercise on the immune system in eight- to seventeen-year-old trained and untrained boys.

OBJECTIVES: To determine the immunologic response to a brief bout of intense exercise in children and to determine the effects of prolonged activity and maturation level of the subjects on this response. STUDY DESIGN: We determined counts of leukocytes and their subsets, counts of lymphocytes and their subsets, and natural killer (NK) cell activity and cell number before and 3 and 60 minutes after a Wingate anaerobic test (WAnT) in 16 male swimmers (9 to 17 years of age) and 17 male nonswimmers (9 to 17 years of age). Subjects were also categorized by pubertal status based on Tanner staging and by level of physical activity. The Student t test and analysis of variance were used to determine statistical significance, with values expressed as mean +/- SEM. RESULTS: Three minutes after the WAnT, all children had increases in leukocytes (28%), lymphocytes (43%), and NK cells (395%) (p < 0.01). Swimmers had less baseline NK cell activity (54 +/- 6 cytolytic units) than nonswimmers (87 +/- 10 cytolytic units) after the WAnT (p < 0.01), although both groups showed an increase to similar levels of NK activity 3 minutes after exercise. Pubertal effects on these responses were not significant. CONCLUSIONS: Our results demonstrate transient leukocytosis, lymphocytosis, and increases in NK cell number and activity in 8- to 17-year-old boys after a brief bout of intense exercise. Formal athletic training appears to be associated with a lower baseline NK cell activity, and yet such activity is still within the normal range for this age group. Further investigations are necessary to determine the impact of such training on overall health and the ability to fight infection.

NMDA receptor activation during epileptiform responses in the dentate gyrus of epileptic patients.

We previously showed that a low frequency (1 Hz) train of perforant path stimulation evokes burst discharges in the dentate gyrus of hippocampal slices obtained from patients surgically treated for intractable temporal lobe epilepsy. We report here that multiple population spikes that characterize the burst discharge are blocked reversibly by the specific NMDA receptor antagonist, D-(-)-2-amino-5-phosphonovaleric acid (D-APV). The epileptiform discharge evoked in human dentate gyrus by stimulation trains of 1 Hz could be reproduced in the rat dentate gyrus in vitro by the same stimulation protocol but required the presence of low concentrations (0.2-0.6 mM) of extracellular magnesium. We suggest that low frequency orthodromic stimulation of dentate granule cells through the perforant path progressively evokes an increase in the activation of NMDA receptors resulting in burst discharges in tissue from epileptic patients.

Somatic growth and developmental functioning in children receiving prolonged home total parenteral nutrition.

Growth and psychomotor development in nine infants receiving prolonged home total parenteral nutrition (TPN) were studied longitudinally from infancy to 3 years of age. Although these children had received TPN for, on average, 79% of their lives, normalization of somatic growth occurred by 2 years of age in all of them. Three children maintained average or above average levels of developmental performance over the 3-year study period. Another four children had initially delayed development but average or above average developmental scores by 18 months. In two children the rate of development gradually slowed without obvious cause, so that by 3 years they functioned in the below average to mildly retarded range.