How to Maintain Maximal Straight Path Running Speed on a Curved Path in Sprint Events

This study aims to clarify the ideal technique for running on a curved path during sprinting events. Participants were twelve male track and field athletes including long jumpers and sprinters. The participants performed a 60-m sprint with maximal effort on straight and curved paths. Participants were divided into "good curve runners" and "poor curve runners" according to the curved path running speed relative to that of the straight path. Kinematic variables and ground reaction forces (GRFs) were registered and compared between the groups and paths. The running speed, step length, and flight distance of the outside leg on the curved path were lower than on the straight path only in poor curve runners. The medial-lateral GRF and impulse showed an increase during curved path running for both groups. However, the maximum posterior GRF and impulse decreased only in poor curve runners. The ideal technique for running on a curved path is to maintain the same kinematics and kinetics in the sagittal plane as on a straight path.

Involvement of corticotropin-releasing factor and corticotropin-releasing factor 2 receptors in pathogenesis of ischemia/reperfusion-induced enteritis in rats

We herein investigated, using a corticotropin-releasing factor (CRF) agonist and antagonists, whether CRF plays a role in the pathogenesis of ischemia/reperfusion-induced small intestinal lesions in rats. Under pentobarbital anesthesia, the superior mesenteric artery was clamped (ischemia) for 75 min, followed by reperfusion with removal of the clamp. After a 24-h reperfusion, the area of hemorrhagic lesions that developed in the small intestine was measured. Urocortin I (CRF receptor 1/2 agonist), astressin (CRF receptor 1/2 antagonist), NBI27914 (CRF receptor 1 antagonist), or astressin 2B (CRF receptor 2 antagonist) was administered i.v. twice: 5 min before ischemia and 6 hours after reperfusion. Ischemia/reperfusion caused hemorrhagic lesions in the small intestine in ampicillin- and aminoguanidine-inhibitable manners, accompanied by enterobacterial invasion and the up-regulation of inducible nitric oxide synthase expression and myeloperoxidase activity. The severity of ischemia/reperfusion-induced lesions was significantly reduced by astressin and astressin 2B, but not by NBI27914, with the suppression of bacterial invasion, myeloperoxidase activity, and inducible nitric oxide synthase expression. In contrast, urocortin I markedly aggravated these lesions, and this response was completely abrogated by the co-administration of astressin 2B, but not NBI27914. The gene expression of CRF, CRF receptor 1, and CRF receptor 2 was observed in the small intestine, and remained unchanged following ischemia/reperfusion. These results suggest that ischemia/reperfusion caused hemorrhagic lesions in the small intestine, the pathogenesis of which involved enterobacteria and inducible nitric oxide synthase/nitric oxide. These lesions were aggravated by urocortin I in an astressin 2B-inhibitable manner, but suppressed by astressin in a CRF receptor 2-dependent manner. Endogenous CRF may be involved in the pathogenesis of ischemia/reperfusion-induced enteritis, possibly via the activation of peripheral CRF receptor 2.

Immunohistochemical localization of gastrin-releasing peptide, neuronal nitric oxide synthase and neurone-specific enolase in the uterus of the North American opossum, Didelphis virginiana

The present study has demonstrated the immunohistochemical localization of gastrin-releasing peptide (GRP), neuronal nitric oxide synthase (nNOS) and neurone-specific enolase (NSE) in the uterus of the North American opossum. Although the presence of GRP, nNOS and NSE has been reported recently in the uterus of eutherian species this is the first description of these peptides in a metatherian species. Metatherian mammals are of interest because in these species it is the prolonged lactation phase of development that is the period of primary reproductive investment rather than intrauterine development as is true of eutherian mammals. The opossum, like other marsupial species, has a very abbreviated gestation period which in Didelphis lasts only 12.5 days. GRP was localized in the cytoplasm of cells forming the surface lining epithelium and the glandular epithelium of the opossum endometrium late in pregnancy, at 11.5 days of gestation. Likewise, immunoreactivities of nNOS and NSE were found primarily within the epithelial cells of the endometrium at 11.5 days of gestation. As these peptides and enzymes appear primarily at the time of establishment of the yolk sac placenta (between day 10 and day 12.5 gestation), the present results strongly suggest that these factors may play a fundamental role in the placentation of the opossum.