Parotid secretion of alpha-amylase and potassium (K+) was determined in young adults following intense exercise. Exercise stress led to a significant elevation in alpha-amylase and K+ secretion, indicating an activation of adrenergic receptors supplying the parotid gland. Evidence of circadian variation or adaptation over days was not found.
Mouse embryo-derived AKR-2B fibroblasts and murine fibrosarcoma cells (the 1591 cell line) were transfected with a murine transforming growth factor-beta 1 (TGF beta 1) cDNA under the transcriptional control of either the simian virus-40 early promoter or the cytomegalovirus promoter/enhancer. Selected clones secreted 2- to 4-fold more TGF beta-competing activity into their media than the parental cell line or neomycin-transfected controls. The TGF beta 1 released into the cell-conditioned medium was latent. Despite the latency of the overexpressed TGF beta 1, TGF beta 1-transfected cells exhibited phenotypic features of TGF beta 1-treated cells. When confluent, the TGF beta 1-transfected cells had the morphological characteristics of the parental cells that have been treated with active TGF beta 1. AKR-2B cells that expressed higher levels of TGF beta 1 also expressed high levels of c-sis and c-myc mRNAs and decreased TGF beta 2 and TGF beta 3 mRNAs in the same manner as parental AKR-2B cells that had been treated with active TGF beta 1. The transfected 1591 cells that overexpressed TGF beta 1 bound less [125I]TGF beta 1 than did parental 1591 cells, but after a mild acid wash demonstrated an increase in [125I]TGF beta 1 binding. Our results suggest that these TGF beta 1-transfected fibroblast and fibrosarcoma cells have the capacity to activate TGF beta; however, as very little activated TGF beta is detected in the medium, it is hypothesized that these cells activate latent TGF beta 1 and bind the activated TGF beta 1, thus acquiring a phenotype consistent with TGF beta 1-treated cells.
This retrospective analysis of cross-country (XC) and downhill (DH) injuries is based on the Consumer Product Safety Commission (CPSC) National Electronic Injury Surveillance System (NEISS) data files and a survey of XC and DH skiing population demographics conducted by the National Ski Retailers Association (NSRA). The study finds that within each sport, the injury population and population at risk demographics are quite similar, but there are significant differences between the two sports in terms of the injury patterns and between the two populations at risk. There are significant interactions between the two sports with respect to gender. The mean levels of severity of injury are not significantly different. There are implications with regard to injury mechanisms as well as hardware factors.
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