Comparison of GC/EI-MS and CF-IRMS in expiratory breath ¹³CO₂ stable isotope dilution

We investigated the potential of a GC/Ei-MS method as an alternative to IRMS in breath ¹³CO₂ / ¹²CO₂ analysis

Epidural blockade and the catabolic response to surgery : an integrated analysis of perioperative protein and glucose metabolism using stable isotope kinetics in the fasted and fed state

The present project investigated the effect of epidural blockade with local anesthetic on the catabolic stress response during and immediately after abdominal surgery in fasting patients and during infusion of glucose at 2 mg·kg-1·min-1. The kinetics of glucose and protein metabolism were assessed by the stable isotope tracers [6,6-2H2]glucose and L-[1-13C]-leucine.Epidural blockade was associated with a lower plasma glucose concentration and glucose production when compared to control subjects in the fasted state. Whole body protein breakdown, amino acid oxidation and protein synthesis were suppressed during surgery, and epidural blockade had no modifying effect on perioperative protein metabolism. The suppression of endogenous glucose production by exogenous glucose was more pronounced in the presence of epidural blockade. Perioperative protein metabolism, however, was not influenced by epidural blockade during glucose infusion.Although epidural blockade suppressed glucose metabolism both in the fasted state and during glucose administration, it failed to exert a modifying effect on perioperative protein metabolism

Insulin Preconditioning Elevates p-Akt and Cardiac Contractility after Reperfusion in the Isolated Ischemic Rat Heart

Insulin induces cardioprotection partly via an antiapoptotic effect. However, the optimal timing of insulin administration for the best quality cardioprotection remains unclear. We tested the hypothesis that insulin administered prior to ischemia provides better cardioprotection than insulin administration after ischemia. Isolated rat hearts were prepared using Langendorff method and divided into three groups. The Pre-Ins group (Pre-Ins) received 0.5 U/L insulin prior to 15 min no-flow ischemia for 20 min followed by 20 min of reperfusion. The Post-Ins group (Post-Ins) received 0.5 U/L insulin during the reperfusion period only. The control group (Control) was perfused with KH buffer throughout. The maximum of left ventricular derivative of pressure development (dP/dt(max)) was recorded continuously. Measurements of TNF-α and p-Akt in each time point were assayed by ELISA. After reperfusion, dP/dt(max) in Pre-Ins was elevated, compared with Post-Ins at 10 minutes after reperfusion and Control at all-time points. TNF-α levels at 5 minutes after reperfusion in the Pre-Ins were lower than the others. After 5 minutes of reperfusion, p-Akt was elevated in Pre-Ins compared with the other groups. Insulin administration prior to ischemia provides better cardioprotection than insulin administration only at reperfusion. TNF-α suppression is possibly mediated via p-Akt leading to a reduction in contractile myocardial dysfunction

High-dose insulin therapy reduces postoperative liver dysfunction and complications in liver resection patients through reduced apoptosis and altered inflammation

Context: An exaggerated inflammatory response in patients undergoing major liver resection coupled with poor nutrition diminishes liver regenerative capacity and increases the risk of postoperative complications. Objectives: Our objective was to evaluate the biological context leading to better clinical outcomes in patients undergoing liver resection coupled with hyperinsulinemic-normoglycemic clamp vs. standard care (insulin sliding care). Design and Setting: This study was a fundamental research analysis of a patient subset from a randomized-controlled study at the McGill University Health Center. Patients and Intervention: Thirty consenting patients participating in a randomized clinical trial for liver resection received either hyperinsulinemic-normoglycemic clamp technique with 24-h preoperative carbohydrate load (intervention) or standard glucose control through insulin sliding scale treatment (control). Main Outcome Measures: Liver biopsies and plasma samples were taken at various time points before and after surgery. Primary measures included mRNA quantitation for genes related to insulin signaling, inflammation, and proliferation; proinflammatory cytokines at various time points; and liver function markers. These measurements were associated with clinical outcomes. Results: The hyperinsulinemic-normoglycemic clamp technique reduced postoperative liver dysfunction, infections, and complications. Markers of energy stores indicated higher substrate availability. Cytokine expression pattern was altered (TNF-α, IL-8,monocyte chemoattractant protein-1, IL-6, IL-10, and C-reactive protein). Apoptosis was markedly reduced, whereas the complement system was unaltered. Conclusion: The hyperinsulinemic-normoglycemic clamp technique reduced postoperative negative outcomes by suppressing apoptosis. This phenomenon appears to be linked with higher substrate availability and altered cytokine secretion profile and may provide a long-term benefit of this therapy on liver resection patients