Plasma lipid concentrations in professional cyclists after competitive cycle races

Summary Plasma lipid concentrations were measured in professional cyclists at the beginning of the training season and both before the start and at the end of two cycle races of similar length (800 and 900 km in 6 days). Plasma concentrations of triglyceride, total and low density lipoprotein-cholesterol (LDL-C) and total cholesterol: high density lipoprotein-cholesterol (HDL-C) ratio were significantly lower and HDL-C concentrations significantly higher in cyclists compared to values in matched sedentary controls. At the end of the races, plasma concentrations of triglyceride and LDL-C were further reduced and HDL-C concentrations had increased compared to values at the start. At the end of the races, plasma concentrations of HDL-C were inversely correlated (r= – 0.28,n = 45,P < 0.05) with triglyceride plasma concentrations. Body fat content, assessed as the sum of skinfold thicknesses was slightly reduced at the end of the race compared to the starting values. There was no significant correlation between skinfold thickness and plasma concentrations of HDL-C. Total plasma fatty acid concentrations were reduced and nonesterified fatty acids concentrations were increased at the end of the race compared to resting values. Consequently, the plasma concentrations of esterified fatty acids were significantly reduced after the race and there was a redistribution of the nonesterified fatty acids. The relative amounts of single fatty acids in the total fatty acid pool remained, however, remarkably constant. In conclusion, the results presented suggested that physical exercise, performed at the level of professional cyclists in a race, was an independent modifier of plasma lipid concentrations.     

Acute hypoxia does not alter inter-alveolar perfusion distribution in unanesthetized rats

Effects of hypoxic vasoconstriction on inter-alveolar perfusion distribution (< or =1000 alveoli) have not been studied. To address this, we measured inter-alveolar perfusion distribution in the lungs of unanesthetized rats breathing 10% O(2). Perfusion distributions were measured by analyzing the trapping patterns of 4 microm diameter fluorescent latex particles infused into the pulmonary circulation. The trapping patterns were statistically quantified in confocal images of the dried lungs. Trapping patterns were measured in lung volumes that ranged between less than 1 and 1300 alveoli, and were expressed as the log of the dispersion index (logDI). A uniform (statistically random) perfusion distribution corresponds to a logDI value of zero. The more this value exceeds zero, the more the distribution is clustered (non-random). At the largest tissue volume (1300 alveoli) logDI reached a maximum value of 0.68+/-0.42 (mean+/-s.d.) in hypoxic rats (n = 6), 0.50+/-0.38 in hypercapnic rats (n.s.) and 0.48+/-0.25 in air-breathing controls (n.s.). Our results suggest that acute hypoxia did not cause significant changes in inter-alveolar perfusion distribution in unanesthetized, spontaneously breathing rats.     

肺密度三维定量分析对急性肺栓塞的诊断价值

【摘要】目的:探讨肺密度三维定量分析对急性肺栓塞的诊断价值。方法:回顾性收集行CT肺动脉造影（CTPA）检查者,证实为肺栓塞者195例,非肺栓塞者177例,两位影像科医生对CTPA进行阅读,记录栓子位置以及间接征象。结果:肺栓塞患者最常见的临床症状气促、咳嗽、胸痛分别占41%、39%、34%。53%的肺栓塞患者具有明确的危险因素。共发现412个栓子,间接征象在急性肺栓塞和非肺栓塞患者中出现率具有显著性差异（P<0.05）,包括:马赛克征（20.3％ vs 0％）、磨玻璃影（23.1% vs 9.4%）、肺实变（46.7% vs 18.8%）、肺不张（17.2% vs 2.8%）、胸腔积液（34.9% vs 23.3%）、胸膜肥厚粘连（77.8% vs 25.1%）。肺密度分析发现的肺野局限性低密度区在栓塞组和非栓塞组具有差别（47.2% vs 13.9%, P<0.05）。且局限性密度减低区与栓子位置的符合率为89.2%。结论:基于肺密度三维定量分析获得的局限性肺密度改变,结合肺栓塞患者的临床信息与CTPA其他间接征象对急性非栓塞诊断具有提示作用。