Eucapnic Voluntary Hyperpnea: Gold Standard for Diagnosing Exercise-Induced Bronchoconstriction in Athletes?

In athletes, a secure diagnos is of exercise-induced bronchoconstriction (EIB) is dependent on objective testing. Evaluating spirometric indices of airflow before and following an exercise bout is intuitively the optimal means for the diagnosis; however, this approach is recognized as having several key limitations. Accordingly, alternative indirect bronchoprovocation tests have been recommended as surrogate means for obtaining a diagnosis of EIB. Of these tests, it is often argued that the eucapnic voluntary hyperpnea (EVH) challenge represents the ‘gold standard’. This article provides a state-of-the-art review of EVH, including an overview of the test methodology and its interpretation. We also address the performance of EVH against the other functional and clinical approaches commonly adopted for the diagnosis of EIB. The published evidence supports a key role for EVH in the diagnostic algorithm for EIB testing in athletes. However, its wide sensitivity and specificity and poor repeatability preclude EVH from being termed a ‘gold standard’ test for EIB

Cell-specific microarray profiling experiments reveal a comprehensive picture of gene expression in the C. elegans nervous system

A novel strategy for profiling Caenorhabditis elegans cells identifies transcripts highly enriched in either the embryonic or larval C. elegans nervous system, including 19 conserved transcripts of unknown function that are also expressed in the mammalian brain

Application of high-dose propofol during ischemia improves postischemic function of rat hearts: Effects on tissue antioxidant capacity

Previous studies have shown that reactive oxygen species mediated lipid peroxidation in patients undergoing cardiac surgery occurs primarily during cardiopulmonary bypass. We examined whether application of a high concentration of propofol during ischemia could effectively enhance postischemic myocardial functional recovery in the setting of global ischemia and reperfusion in an isolated heart preparation. Hearts were subjected to 40 min of global ischemia followed by 90 min of reperfusion. During ischemia, propofol (12 μg/mL in saline) was perfused through the aorta at 60 μL/min. We found that application of high-concentration propofol during ischemia combined with low-concentration propofol (1.2 μg/mL) administered before ischemia and during reperfusion significantly improved postischemic myocardial functional recovery without depressing cardiac mechanics before ischemia, as is seen when high-concentration propofol was applied prior to ischemia and during reperfusion. The functional enhancement is associated with increased heart tissue antioxidant capacity and reduced lipid peroxidation. We conclude that high-concentration propofol application during ischemia could be a potential therapeutic and anesthetic strategy for patients with preexisting myocardial dysfunction.link_to_subscribed_fulltex

Propofol enhances ischemic tolerance of middle-aged rat hearts: Effects on 15-F2t-isoprostane formation and tissue antioxidant capacity

Objective: Experimental study has shown that myocardial ischemic tolerance is reduced during middle-age. We investigated the effect of propofol on ischemic tolerance of middle-aged rat hearts. Methods: Hearts of young adult (10 weeks old, Y) and middle-aged rats (20 weeks old, M) were assigned to propofol (P-Y, P-M) and control (C-Y, C-M) groups (n=6 each). Hearts were perfused using a Langendorff preparation with Krebs-Henseleit solution (KH) at constant flow rates. We applied propofol (P-Y, P-M) for 10 min at 12 μg/ml before inducing 40 min global ischemia. During ischemia, saline (C-Y, C-M) or propofol (P-Y, P-M) in saline was perfused through the aorta at 60 μl/min. Propofol in KH was perfused at 12 μg/ml for the first 15 min of reperfusion and subsequently reduced to 5 μg/ml in propofol treatment groups. Coronary effluent was assayed for 15-F2t-isoprostane after equilibration, during ischemia (T1) and at 0.5 (T2) and 5 (T3) min of reperfusion. After 90 min of reperfusion (T4), hearts were harvested to assess tissue antioxidant capacity. Results: In P-Y, we observed an increased latency to ischemic-contracture and a significantly reduced contracture after 35 min ischemia compared to control groups. No ischemic contracture was observed in P-M. There were significantly lower 15-F2t-isoprostane levels in P-M and P-Y than in C-M and C-Y at T1. At T4, the recovery of left ventricular developed pressure in P-M was greater than in P-Y (P<0.05); both were greater than in C-M and C-Y. Conclusion: Propofol enhanced ischemic tolerance of middle-aged hearts, primarily by inhibiting lipid peroxidation. © 2003 European Society of Cardiology. Published by Elsevier Science B.V. All rights reserved.link_to_subscribed_fulltex

Large-dose propofol during cardiopulmonary bypass decreases biochemical markers of myocardial injury in coronary surgery patients: A comparison with isoflurane

We investigated if increasing propofol's dosage to augment its antioxidant capacity during cardiopulmonary bypass (CPB) could confer cardiac protection. Fifty-four coronary artery bypass graft surgery patients were randomly assigned to small-dose propofol (Group P; n = 18), large-dose propofol (Group HiP; n = 18), or isoflurane Group (Group I; n = 18). After the induction, anesthesia was maintained with an inspired concentration of isoflurane 1%-3.5% (Group I) or a continuous infusion of propofol 60 μg·kg·min (Group P) throughout the surgery. In Group HiP, this dose of propofol was increased to 120 μg·kg·min for 10 min before the onset of CPB until 15 min after aortic unclamping and then decreased to 60 μg·kg·min until the end of surgery. The duration of aortic cross-clamping was 83 ± 24, 88 ± 22, and 81 ± 20 min in Group P, Group HiP, and Group I, respectively (P > 0.1). Plasma malondialdehyde, a marker of oxidative stress, was significantly lower at 8 h after CPB, and Troponin I was lower at 24 h after CPB in Group HiP compared with Group P and Group I (P < 0.05). There was a significant reduction in inotropic requirements for separation from CPB in Group HiP compared with Group I. Postoperative systemic vascular resistance was significantly reduced in Group HiP as compared with Group I. Mean cardiac index was significantly higher at 24 h after CPB in Group HiP compared with Group P and Group I (P < 0.05) (Group I, 2.2 ± 0.1; Group P, 2.3 ± 0.2; and Group HiP, 2.8 ± 0.3 L • min·m, respectively). The duration of intensive care unit stay was significantly shorter in Group Hi-P compared with Group I. We conclude that administration of a large dose of propofol during CPB attenuates postoperative myocardial cellular damage as compared with isoflurane or small-dose propofol anesthesia. © 2006 by International Anesthesia Research Society.link_to_subscribed_fulltex

Clinical significance of plasma free 15-F2t-isoprostane concentration during coronary artery bypasses graft surgery

OBJECTIVE: To analyse retrospectively the variation of plasma 15-F2t-isoprostane concentration during cardiac surgery and the relation with early myocardial dysfunction following normothemic cardiac surgery. METHODS: Thirty patients scheduled for coronary artery bypass graft surgery using normothermic cardiopulmonary bypass (CPB) and warm intermittent blood, crystalloid cardioplegia were enrolled. Patients were divided into two groups treated with (group II) or without (group I) positive inotropic drugs. Central venous blood was sampled at baseline, 30 minutes after global myocardial ischemia, 10, 30 and 120 minutes after aortic declamping (reperfusion). Plasma free 15-F2t-isoprostane was measured with enzyme immunoassay (EIA) using a highly specific rabbit 15-F2t-isoprostane antibody. Cardiac index (CI) was monitored intraoperatively and up to 6 hours following surgery. RESULTS: Plasma free 15-F2t-isoprostane increased significantly during ischemia, remained elevating at 10 minutes after reperfusion (P<0.05 vs. baseline) and began to decline at 30 minutes after reperfusion in the whole population. 15-F2t-isoprostane underwent exponential decay and returned to baseline at 30 minutes after reperfusion in group I that did not need any postoperative inotropic support. In contrast, 15-F2t-isoprostane further increased upon reperfusion and remained significantly higher than baseline at 30 minutes after reperfusion (P<0.05) in group II that needed two or more inotropes to maintain CI greater than 2.2 L x min(-1) x m(-2). Postoperative CI was significantly inversely correlated with the percentage change in plasma free 15-F2t-isoprostane concentration from 10 to 30 minutes after reperfusion (r=-0.95, P<0.01). CONCLUSION: It shows a close relationship between free plasma concentrations of 15-F2t-isoprostane and early postoperative cardiac function following coronary artery bypass graft surgery.link_to_subscribed_fulltex