Journal of applied physiology
-
Athletes with spinal cord injury (SCI), and in particular tetraplegia, have an increased risk of heat strain and consequently heat illness relative to able-bodied individuals. Strategies that reduce the heat strain during exercise in a hot environment may reduce the risk of heat illness. To test the hypotheses that precooling or cooling during intermittent sprint exercise in a heated environment would attenuate the rise in core temperature in tetraplegic athletes, eight male subjects with SCI (lesions C(5)-C(7); 2 incomplete lesions) undertook four heat stress trials (32.0 +/- 0.1 degrees C, 50 +/- 0.1% relative humidity). ⋯ Moreover, perceived exertion was lower during Pre (13 +/- 2; P < 0.01) and Dur (12 +/- 1; P < 0.01) compared with Con (14 +/- 2). These results suggest that both precooling and cooling during intermittent sprint exercise in the heat reduces thermal strain in tetraplegic athletes. The cooling strategies also appear to show reduced perceived exertion at equivalent time points, which may translate into improved functional capacity.
-
Comparative Study
Neutrophil inhibition with L-selectin-directed MAb improves or worsens survival dependent on the route but not severity of infection in a rat sepsis model.
Both route and severity of infection may influence immunomodulator agents in sepsis. We studied the effect of each variable on HRL-3, an L-selectin-directed MAb that inhibits neutrophil function, in a rat sepsis model. Animals (n = 800) were randomized to be treated with either HRL-3 or placebo and to receive Escherichia coli either intravenously (IV) or intrabronchially (IB) in doses producing low or high mortality rates. ⋯ In contrast, with IB E. coli HRL-3 reduced the hazards ratio early (-1.1 +/- 0.36) but worsened it late (0.87 +/- 0.23) (P = 0.002 for both effects over all E. coli doses) in patterns significantly different from IV E. coli (P < 0.0001). Compared with control, although HRL-3 did not alter lung neutrophil numbers or injury score at 6 or 168 h with IV E. coli (P = ns for all), it reduced both early and increased them late with IB E. coli (P
-
Comparative Study
Spatial pattern of ventilation-perfusion mismatch following acute pulmonary thromboembolism in pigs.
We studied the spatial distribution of the abnormal ventilation-perfusion (Va/Q) units in a porcine model of acute pulmonary thromboembolism (APTE), using the fluorescent microsphere (FMS) technique. Four piglets ( approximately 22 kg) were anesthetized and ventilated with room air in the prone position. Each received approximately 20 g of preformed blood clots at time t = 0 min via a large-bore central venous catheter, until the mean pulmonary arterial pressure reached 2.5 times baseline. ⋯ Redistribution pattern was mostly seen in regional Q, whereas Va remained relatively unchanged. We concluded that the hypoxemia seen after APTE could be explained by the mechanical diversion of Q to the less embolized regions because of the vascular obstruction by clots elsewhere. These low Va/Q units created by high flow, rather than low Va, accounted for most of the resultant hypoxemia.
-
Comparative Study
Ultrasound: a reproducible method to measure conduit vein compliance.
Classical venous occlusion plethysmography (VOP) of the leg, often used to assess venous compliance, measures properties of the whole calf, including volume changes at the arterial side and the interstitial fluid accumulation that occurs as a result of the enhanced capillary pressure during venous occlusion. We present an ultrasound technique to measure the compliance of one major conduit vein in the leg. Ultrasound measurements of the popliteal vein were compared with classical VOP measurements, which were performed simultaneously in one subject. ⋯ Ultrasound provides reproducible measurements with short- and long-term coefficients of variation ranging from 10 to 15% for popliteal vein compliance and from 2 to 9% for absolute diameters at the different venous pressure steps. In addition, by using ultrasound, we were able to detect an 80% reduction in the compliance of the popliteal vein in SCI individuals compared with controls (P < 0.01). In conclusion, ultrasound is a suitable and reproducible method to measure conduit vein compliance and provides the possibility to specifically assess compliance of one vein instead of the whole calf.
-
Comparative Study
Pulmonary and extrapulmonary acute lung injury: inflammatory and ultrastructural analyses.
To test whether pulmonary and extrapulmonary acute lung injury (ALI) of identical mechanical compromise would express diverse morphological patterns and immunological pathways. For this purpose, a model of pulmonary (p) and extrapulmonary (exp) ALI with similar functional changes was developed and pulmonary morphology (light and electron microscopy), cytokines levels, and neutrophilic infiltration in the bronchoalveolar lavage fluid (BALF), elastic and collagen fiber content in the alveolar septa, and neutrophil apoptosis in the lung parenchyma were analyzed. BALB/c mice were divided into four groups. ⋯ Neutrophils in the BALF were more frequent in ALIp than in ALIexp. ALIp showed more extensive injury of alveolar epithelium, intact capillary endothelium, and apoptotic neutrophils, whereas the ALIexp group presented interstitial edema and intact type I and II cells and endothelial layer. In conclusion, given the same pulmonary mechanical dysfunction independently of the etiology of ALI, insult in pulmonary epithelium yielded more pronounced inflammatory responses, which induce ultrastructural morphological changes.