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51.
Rodger J Vitale PN Tee LB King CE Bartlett CA Fall A Brennan C O'Shea JE Dunlop SA Beazley LD 《Molecular and cellular neurosciences》2004,25(1):56-68
During visual system development, interactions between Eph tyrosine kinase receptors and their ligands, the ephrins, guide retinal ganglion cell (RGC) axons to their topographic targets in the optic tectum. Here we show that Eph/ephrin interactions are also involved in restoring topography during RGC axon regeneration in goldfish. Following optic nerve crush, EphA/ephrin-A interactions were blocked by intracranial injections of recombinant Eph receptor (EphA3-AP) or phospho-inositol phospholipase-C. Topographic errors with multiple inputs to some tectal loci were detected electrophysiologically and increased projections to caudal tectum demonstrated by RT-97 immunohistochemistry. In EphA3-AP-injected fish, ephrin-A2-expressing cells in the retino-recipient tectal layers were reduced in number compared to controls and their distribution was no longer graded. The findings, supported by in vitro studies, implicate EphA/ephrin-A interactions in restoring precise topography and in regulating ephrin-A2 expression during regeneration. 相似文献
52.
Tee GB Rasool AH Halim AS Rahman AR 《Journal of pharmacological and toxicological methods》2004,50(1):73-78
INTRODUCTION: Human postocclusive forearm skin reactive hyperemia is not only a potential means of identifying early signs of cardiovascular diseases, it can also be used in the assessment of local microvascular response to topically applied compounds on skin. The method is not fully characterized. In this study, we investigated the influence of occlusion time on postocclusive forearm skin reactive hyperemia using laser Doppler fluximetry (LDF). METHODS: Twenty healthy male volunteers were studied on three separate days (at least 24 h apart) via a randomized design. Volunteers were studied in a supine position while fasted. Laser Doppler probes were placed on the volar surface of the antebrachium. In preliminary studies, 3 min of upper arm blood flow occlusion at suprasystolic pressure was found to be the upper limit of tolerability. Subsequently, volunteers were randomized to receive 1, 2, or 3 min occlusion on 3 different days. Skin blood flux was measured before, during, and after occlusion using LDF. The primary outcome calculated was maximal change in skin blood flux before and after occlusion, expressed in arbitrary units (AU). RESULTS: Skin blood flux changes (mean+/-S.E.M.) after 1, 2, and 3 min occlusion period were 15.39+/-1.27 AU, 24.84+/-1.62 AU, and 32.14+/-1.73 AU, respectively. Using repeated-measures analysis of variance (ANOVA), significant difference (P<.05) in skin blood flux changes were revealed between these three occlusion durations, where 3 min occlusion produced significantly greater in skin blood flux occlusion change compared to 1 and 2 min occlusion. DISCUSSION: Three minutes of occlusion produces the greater postocclusive reactive hyperemia. It is recommended that studies using postocclusive forearm skin reactive hyperemia should occlude the forearm for at least 3 min. 相似文献
53.
Beazley LD Rodger J Chen P Tee LB Stirling RV Taylor AL Dunlop SA 《Journal of neurotrauma》2003,20(11):1263-1270
Optic nerve regeneration in a lizard, Ctenophorus ornatus, is dysfunctional despite survival of most retinal ganglion cells and axon regeneration to the optic tectum. The regenerated retino-tectal projection at 6 months has crude topography but by 1 year is disordered; visually-elicited behavior is absent via the experimental eye. Here, we assess the influence of training on the outcome of optic nerve regeneration. Lizards were trained to catch prey presented within the monocular field of either eye. One optic nerve was then severed and visual stimulation resumed throughout regeneration. In the trained group, presentation was restricted to the eye undergoing optic nerve regeneration; for the untrained group, the unoperated eye was stimulated. Pupil responses returned in trained but not in untrained animals. At 1 year, trained animals oriented to and captured prey; untrained animals demonstrated minimal orienting and failed to capture prey. Regenerated retino-tectal projections were topographic in the trained but not in the untrained group as assessed by in vitro electrophysiological recording and by carbocyanine dye tracing. In vitro electrophysiological recording during application of neurotransmitter antagonists to the tectum revealed that the level of GABAergic inhibition was modest in trained animals but elevated in the untrained group; responses were mainly AMPA-mediated in both groups. We conclude that training improves the behavioral outcome of regeneration, presumably by stabilizing and refining the transient retino-tectal map and preventing a build-up of tectal inhibition. The results suggest that for successful central nerve regeneration to occur in mammals, it may be necessary to introduce training to complement procedures stimulating axon regeneration. 相似文献
54.
An investigation of noise levels in Alberta sawmills 总被引:2,自引:0,他引:2
Koehncke N Taylor M Taylor C Harman L Hessel PA Beaulne P Guidotti T 《American journal of industrial medicine》2003,43(2):156-164
BACKGROUND: Noise exposure in the sawmill industry is an area of concern. This study documents the level of noise exposure in nine sawmills in the province of Alberta, Canada. METHODS: Personal noise monitoring data were collected in nine Alberta sawmills, in winter and in summer (n = 213). Exposures were considered in light of an estimated "real world" noise reduction rating (NRR) calculation assuming use of conventional hearing protection. Limited comparisons were made with spot area monitoring data. RESULTS: Only 10% of the personal monitoring measurements were below the Alberta 8-hr exposure limit of 85 dBA. Twenty-seven percent of the personal monitoring measurements were 95 dBA or higher. Worker enclosures played a large role in reducing noise exposure. There were no significant differences between seasons in noise category distributions (P = 0.61). The planermen and planer infeed operators had the highest percentage of personal monitoring measurements 95 dBA or higher (62% and 82%, respectively). CONCLUSIONS: Based on a conservative formula, a risk of excess noise exposure could exist even when wearing required hearing protection due to very high noise levels found in planing operations in sawmills. 相似文献
55.
Burns L Ashwell M Berry J Bolton-Smith C Cassidy A Dunnigan M Khaw KT Macdonald H New S Prentice A Powell J Reeve J Robins S Teucher B 《The British journal of nutrition》2003,89(6):835-840
The UK Food Standards Agency (FSA) convened a group of expert scientists to discuss and review UK FSA- and Department of Health-funded research on diet and bone health. This research focused on the lifestyle factors that are amenable to change and may significantly affect bone health and the risk of osteoporotic fracture. The potential benefits of fruits and vegetables, meat, Ca, vitamins D and K and phyto-oestrogens were presented and discussed. Other lifestyle factors were also discussed, particularly the effect of physical activity and possible gene-nutrient interactions affecting bone health. 相似文献
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We report 2 cases of bacteremia due to "Helicobacter rappini" in 2 young, homosexual men, including the first report of H. rappini in a human immunodeficiency virus-positive patient. Blood cultures showed a spiral, fusiform, gram-negative bacterium with bipolar sheathed flagella. 相似文献
58.
Optimal therapy for patients with acute myeloid leukemia (AML) in first complete remission (CR-1) remains the subject of debate: with the possibilities of chemotherapy alone, autologous (auto) or allogeneic (allo) hematopoietic stem cell transplantation (HSCT). We undertook a retrospective analysis of AML patients aged below 46 years and in CR-1, who had undergone auto- or allo-HSCT in our institution, to determine the factors associated with a better outcome. Between September 1985 and April 2003, 81 patients underwent autologous (n = 29) or allogeneic (n = 52) HSCT in CR-1. With a median follow-up of 10 years, the probability of 15-year overall survival (OS) was 51%[95% confidence interval (CI) = 32 - 70%] for auto-HSCT vs. 55% (95% CI = 42 - 69) for allo-HSCT, respectively (P = 0.92). The cumulative incidence of relapse at 3 years was 49% (95% CI = 30 - 67) (auto) vs. 21% (95% CI = 10 - 30) (allo), respectively. Non-relapse-related mortality at 3 years was 5% (95% CI = 0 - 14) (auto) vs. 17% (95% CI = 7 - 28) (allo), respectively. This retrospective analysis confirmed that auto- and allo-HSCT led to similar OS. The significantly lower incidence of relapse amongst allograft recipients was balanced by an increased incidence of death in CR. 相似文献
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