The association of systemic inflammatory markers with indicators of stress and cardiac necrosis in patients undergoing aortic valve replacement and revascularization surgeries

The aim was to investigate: changes of inflammatory, stress and cardiac response in patients undergoing open heart surgeries up to five days after the procedure; the association between inflammatory, stress and cardiac response and whether changes in a certain marker can predict short-term patient outcome. Ninety patients were divided into three groups, 30 participants each (on-pump,off-pump revascularization and valve replacement group). The following markers were measured:complete blood count, CRP, IL-6, IL-10, leptin, resistin, monocyte chemoattractant protein-1 (MCP-1), cortisol, CK and hsTnT in 5 points. Resistin increased in all three groups. Lower IL-10 levels were found after the surgery and higher levels of leptin and MCP-1 in the off-pump than in the on-pump group. Off-pump group had higher values of IL-6, IL-10, leptin, resistin and MCP-1 and lower levels of CK and hsTnT 24 after surgery than the on-pump group. We found significant correlation between MCP-1 and resistin. The difference between resistin at time points 2 and 3 significantly predicted transfusion needs; while the difference between CRP and resistin before and at the end of the surgery together with the difference between leukocytes at the end and 24 hours after the surgery predicted the use of inotropic agents/vasopressors. Cardiac surgeries cause an increase of inflammatory, stress and cardiac markers. Only resistin correlated with MCP-1 which confirms the link between resistin secreted form infiltrated macrophages and enhanced release of MCP-1.

Growth of mountain belts in central Asia triggers a new collision zone in central India

Several unusual strong earthquakes occurred in central India along the Narmada-Son Lineament (NSL) zone, far from active plate boundaries. To understand the role of collisional processes in the origin of this seismicity, we develop a numerical thermomechanical model of shortening between the Indian Plate and Asia. We show that at the final stage of collision, the shortening rate of the high mountain areas slows. The continuing convergence of India and Asia triggers the initiation of a new collision zone in continental part of India. Various geological and geophysical observations indicate that the NSL is a weakest zone with northward thrusting of the thinner central Indian lithosphere underneath the thicker northern part of the Indian Plate. We hypothesize that the NSL was reactivated during the final stage of the India Asia convergence and it will possibly form a new mountain belt within the Indian continent.

Mitral regurgitation and coronary artery bypass surgery: comparison of mitral valve repair and replacement

BACKGROUND

The aim of this retrospective study was to determine if there is a statistically significant difference (p < or = 0.05) between mitral valve repair (MVRp) with concomitant surgical revascularization of the myocardium (CABG) and mitral valve replacement (MVR) with concomitant CABG, considering the duration of surgery, early postoperative morbidity, in-hospital mortality, length of stay in the Intensive Care Unit (ICU) and overall in-hospital stay.

METHODS

Between January 1st 2006 and December 31st 2008, 75 patients underwent surgery for mitral regurgitation and ischemic heart disease. Patients were divided in two groups determined by the procedure that was performed on the mitral valve (MVRp + CABG group had 34 patients, MVR + CABG group had 41 patients). All the patients were operated by the same surgical team and received the usual anaesthesia protocol.

RESULTS

Patients in the MVR + CABG group had statistically significant higher EuroSCORE risk levels, higher NYHA status and higher incidence of postoperative low cardiac output syndrome (LCOS). Neurological complications showed statistically significant higher incidence in the MVRp + CABG group. There was no statistically significant difference in regard to in-hospital mortality between these two groups. Patients in the MVR + CABG group had statistically significant longer in-hospital stay.

CONCLUSIONS

Mitral valve repair and mitral valve replacement are complementary methods considering early postoperative morbidity and mortality. Higher incidence of LCOS and in-hospital stay in the MVR + CABG group was to be expected on behalf of poorer preoperative status.

Infusion with the antioxidant N-acetylcysteine attenuates early adaptive responses to exercise in human skeletal muscle

AIM

Production of reactive oxygen species (ROS) in skeletal muscle is markedly increased during exercise and may be essential for exercise adaptation. We, therefore, investigated the effects of infusion with the antioxidant N-acetylcysteine (NAC) on exercise-induced activation of signalling pathways and genes involved in exercise adaptation in human skeletal muscle.

METHODS

Subjects completed two exercise tests, 7 days apart, with saline (control, CON) or NAC infusion before and during exercise. Exercise tests comprised of cycling at 71% VO(2peak) for 45 min, and then 92% VO(2peak) to fatigue, with vastus lateralis biopsies at pre-infusion, after 45-min cycling and at fatigue.

RESULTS

Analysis was conducted on the mitogen-activated protein kinase signalling pathways, demonstrating that NAC infusion blocked the exercise-induced increase in JNK phosphorylation, but not ERK1/2, or p38 MAPK. Nuclear factor-κB p65 phosphorylation was unaffected by exercise; however, it was reduced in NAC at fatigue by 14% (P < 0.05) compared with pre-infusion. Analysis of exercise and/or ROS-sensitive genes demonstrated that exercise-induced mRNA expression is ROS dependent of MnSOD, but not PGC-1α, interleukin-6, monocyte chemotactic protein-1, or heat-shock protein 70.

CONCLUSION

These results suggest that inhibition of ROS attenuates some skeletal muscle cell signalling pathways and gene expression involved in adaptations to exercise.

N-acetylcysteine enhances muscle cysteine and glutathione availability and attenuates fatigue during prolonged exercise in endurance-trained individuals

The production of reactive oxygen species in skeletal muscle is linked with muscle fatigue. This study investigated the effects of the antioxidant compound N-acetylcysteine (NAC) on muscle cysteine, cystine, and glutathione and on time to fatigue during prolonged, submaximal exercise in endurance athletes. Eight men completed a double-blind, crossover study, receiving NAC or placebo before and during cycling for 45 min at 71% peak oxygen consumption (VO2 peak) and then to fatigue at 92% VO2 peak. NAC was intravenously infused at 125 mg.kg(-1).h(-1) for 15 min and then at 25 mg.kg(-1).h(-1) for 20 min before and throughout exercise. Arterialized venous blood was analyzed for NAC, glutathione status, and cysteine concentration. A vastus lateralis biopsy was taken preinfusion, at 45 min of exercise, and at fatigue and was analyzed for NAC, total glutathione (TGSH), reduced glutathione (GSH), cysteine, and cystine. Time to fatigue at 92% VO2 peak was reproducible in preliminary trials (coefficient of variation 5.6 +/- 0.6%) and with NAC was enhanced by 26.3 +/- 9.1% (NAC 6.4 +/- 0.6 min vs. Con 5.3 +/- 0.7 min; P <0.05). NAC increased muscle total and reduced NAC at both 45 min and fatigue (P <0.005). Muscle cysteine and cystine were unchanged during Con, but were elevated above preinfusion levels with NAC (P <0.001). Muscle TGSH (P <0.05) declined and muscle GSH tended to decline (P=0.06) during exercise. Both were greater with NAC (P <0.05). Neither exercise nor NAC affected whole blood TGSH. Whereas blood GSH was decreased and calculated oxidized glutathione increased with exercise (P <0.05), both were unaffected by NAC. In conclusion, NAC improved performance in well-trained individuals, with enhanced muscle cysteine and GSH availability a likely mechanism.

Intense exercise up-regulates Na+,K+-ATPase isoform mRNA, but not protein expression in human skeletal muscle

Characterization of expression of, and consequently also the acute exercise effects on, Na(+),K(+)-ATPase isoforms in human skeletal muscle remains incomplete and was therefore investigated. Fifteen healthy subjects (eight males, seven females) performed fatiguing, knee extensor exercise at approximately 40% of their maximal work output per contraction. A vastus lateralis muscle biopsy was taken at rest, fatigue and 3 and 24 h postexercise, and analysed for Na(+),K(+)-ATPase alpha(1), alpha(2), alpha(3), beta(1), beta(2) and beta(3) mRNA and crude homogenate protein expression, using Real-Time RT-PCR and immunoblotting, respectively. Each individual expressed gene transcripts and protein bands for each Na(+),K(+)-ATPase isoform. Each isoform was also expressed in a primary human skeletal muscle cell culture. Intense exercise (352 +/- 69 s; mean +/-s.e.m.) immediately increased alpha(3) and beta(2) mRNA by 2.4- and 1.7-fold, respectively (P < 0.05), whilst alpha(1) and alpha(2) mRNA were increased by 2.5- and 3.5-fold at 24 h and 3 h postexercise, respectively (P < 0.05). No significant change occurred for beta(1) and beta(3) mRNA, reflecting variable time-dependent responses. When the average postexercise value was contrasted to rest, mRNA increased for alpha(1), alpha(2), alpha(3), beta(1), beta(2) and beta(3) isoforms, by 1.4-, 2.2-, 1.4-, 1.1-, 1.0- and 1.0-fold, respectively (P < 0.05). However, exercise did not alter the protein abundance of the alpha(1)-alpha(3) and beta(1)-beta(3) isoforms. Thus, human skeletal muscle expresses each of the Na(+),K(+)-ATPase alpha(1), alpha(2), alpha(3), beta(1), beta(2) and beta(3) isoforms, evidenced at both transcription and protein levels. Whilst brief exercise increased Na(+),K(+)-ATPase isoform mRNA expression, there was no effect on isoform protein expression, suggesting that the exercise challenge was insufficient for muscle Na(+),K(+)-ATPase up-regulation.

N-acetylcysteine infusion alters blood redox status but not time to fatigue during intense exercise in humans

Infusion of the antioxidant N-acetylcysteine (NAC) reduces fatigability in electrically evoked human muscle contraction, but due to reported adverse reactions, no studies have investigated NAC infusion effects during voluntary exercise in humans. We investigated whether a modified NAC-infusion protocol (125 mg. kg(-1). h(-1) for 15 min, then 25 mg. kg(-1). h(-1)) altered blood redox status and enhanced performance during intense, intermittent exercise. Eight untrained men participated in a counterbalanced, double-blind, crossover study in which they received NAC or saline (control) before and during cycling exercise, which comprised three 45-s bouts and a fourth bout that continued to fatigue, at 130% peak oxygen consumption. Arterialized venous blood was analyzed for glutathione status, hematology, and plasma electrolytes. NAC infusion induced no severe adverse reactions. Exercise decreased the reduced glutathione (P < 0.005) and increased oxidized glutathione concentrations (P < 0.005); NAC attenuated both effects (P < 0.05). NAC increased the rise in plasma K(+) concentration-to-work ratio (P < 0.05), indicating impaired K(+) regulation, although time to fatigue was unchanged (NAC 102 +/- 45 s; saline 107 +/- 53 s). Thus NAC infusion altered blood redox status during intense, intermittent exercise but did not attenuate fatigue.