Influence of age, sex, balance, and sport participation on development of throwing by children in grades K-8

The purpose of this study was to examine the contributions of age, sex, balance, and sport participation on development of throwing by children in Grades K-8. The subjects were 381 boys and 338 girls (ages 4-14) enrolled in a medium-sized school system in southeastern Maine. Each subject was individually assessed in throwing development and static and dynamic balance. In addition, all subjects completed a survey relative to their participation in school- or community-sponsored sports. To determine the independent effects of age, sex, static balance, dynamic balance, and sport participation within each grade, data were subjected to multiple regression analysis, which indicated that mature throwing development was influenced by sport participation and sex. Boys performed better at all grades.     

Local and distant histopathological effects of unilateral amyloid-beta 25-35 injections into the amygdala of young F344 rats

To determine if amyloid-beta (A beta) induces tau-immunoreactivity (IR) and reactive astrocytosis in vivo, we injected A beta 25-35 (5.0 nmol) into the right amygdala of rats. At 8 days postinjection, the peptide induced tau-2 IR in neuronal cell bodies and processes ipsilaterally in the amygdala, cingulate cortex, and hippocampus. At 32 days postinjection, the intensity of tau-2 IR was greater than at 8 days in the amygdala and hippocampus, but not in the cingulate cortex. Induction of Alz-50 IR also was progressive but the morphology and distribution was different from tau-2 IR. Beaded fibers with occasional neuronal perikarya were visualized with Alz-50, and the IR was primarily observed in the ipsilateral amygdala. In addition, amygdaloid injections of A beta 25-35 induced reactive astrocytosis, particularly in the ipsilateral hippocampus at 32 days postoperatively. To our knowledge, this is the first study to show that in vivo injections of A beta 25-35 induce progressive transsynaptic cytoskeletal and astrogliotic reactions, that gradually spread from the area of injection to brain regions that have prominent efferent connections with that area. These findings also suggest a direct association between plaque and tangle formation in Alzheimer's disease.