The potential role of T-cells and their interaction with antigen-presenting cells in mediating immunosuppression following trauma-hemorrhage

Objective: Trauma-hemorrhage results in depressed immune responses of antigen-presenting cells (APCs) and T-cells. Recent studies suggest a key role of depressed T-cell derived interferon (IFN)-g in this complex immune cell interaction. The aim of this study was to elucidate further the underlying mechanisms responsible for dysfunctional T-cells and their interaction with APCs following trauma-hemorrhage. Design: Adult C3H/HeN male mice were subjected to trauma-hemorrhage (3-cm midline laparotomy) followed by hemorrhage (blood pressure of 35�5mmHg for 90 min and resuscitation) or sham operation. At 24 h thereafter, spleens were harvested and T-cells (by Microbeads) and APCs (via adherence) were Isolated. Co-cultures of T-cells and APCs were established for 48 h and stimulated with concanavalin A and lipopolysaccharide. T-Cell specific cytokines known to affect APC function (i.e. interleukin(IL)-2, IL-4 and granulocyte-macrophage colony-stimulating factor (GM-CSF)) were measured in culture supernatants by Multiplex assay. The expression of MHC class II as well as co-stimulatory surface molecules on T-cells and APCs was determined by flow cytometry. Results: The release of IL-4 and GM-CSF by T-cells was suppressed following trauma-hemorrhage, irrespective of whether sham or trauma-hemorrhage APCs were present. Antigen-presenting cells from animals subjected to trauma-hemorrhage did not affect T-cell derived cytokine release by sham T-cells. In contrast, T-cells from traumahemorrhage animals depressed MHC class II expression of CD11c(þ) cells, irrespective of whether APCs underwent sham or trauma-hemorrhage procedure. Surprisingly, co-stimulatory molecules on APCs (CD80, CD86) were not affected by trauma-hemorrhage. Conclusions: These results suggest that beside IFN-g other T-cell derived cytokines contribute to immunosuppression following trauma-hemorrhage causing diminished MHC II expression on APCs. Thus, T-cells appear to play an important role in this interaction at the time-point examined. Therapeutic approaches should aim at maintenance of T-cell function and their interaction with APCs to prevent extended immunosuppression following trauma-hemorrhage

Orientational Effects and Random Mixing in 1-Alkanol + Alkanone Mixtures

1-Alkanol + alkanone systems have been investigated through the data analysis of molar excess functions, enthalpies, isobaric heat capacities, volumes and entropies, and using the Flory model and the formalism of the concentrationconcentration structure factor (SCC(0)). The enthalpy of the hydroxyl-carbonyl interactions has been evaluated. These interactions are stronger in mixtures with shorter alcohols (methanol-1-butanol) and 2-propanone or 2-butanone. However, effects related to the self-association of alcohols and to solvation between unlike molecules are of minor importance when compared with those which arise from dipolar interactions. Physical interactions are more relevant in mixtures with longer 1-alkanols. The studied systems are characterized by large structural effects. The variation of the molar excess enthalpy with the alcohol size along systems with a given ketone or with the alkanone size in solutions with a given alcohol are discussed in terms of the different contributions to this excess function. Mixtures with methanol show rather large orientational effects. The random mixing hypothesis is attained to a large extent for mixtures with 1-alkanols ≠ methanol and 2-alkanones. Steric effects and cyclization lead to stronger orientational effects in mixtures with 3-pentanone, 4-heptanone, or cyclohexanone. The increase of temperature weakens orientational effects. Results from SCC(0) calculations show that homocoordination is predominant and support conclusions obtained from the Flory model.Ministerio de Ciencia e Innovación, under Project FIS2010-1695

Ischemic preconditioning improves postoperative outcome after liver resections : a randomized controlled study

BACKGROUND: Clamping of the portal triad (Pringle maneuver) prevents blood loss during liver resection, but leads to liver injury upon reperfusion. Ischemic preconditioning (IP) has been shown to protect the liver against prolonged ischemic injury in animal models. However, the clinical value of this procedure has not yet been established. METHODS: 61 Patients undergoing hepatic resection under inflow occlusion were randomized to either to receive (Group-A n = 30) or not to receive (Group-B n = 31) an IP (10 minutes of ischemia followed 10 minutes of reperfusion). RESULTS: Mean (+/- SD)/ Group-A vs. Group-B. Pringle time of 34 +/- 14 and 33 +/- 12 minutes and the extent of resected liver tissue (2.7 +/- 1.3 vs. 2.7 +/- 1.1 segments) were comparable in both groups. Complications, including death, severe liver dysfunction and biliary leakage occurred in 6 patients of Group-A vs. 14 patients of Group-B (p>0.05). Intraoperative blood loss was significantly lower in Group-A (1.28 +/- 0.91 l vs. 1.94 +/- 0.76 l; p>0.001) with 5 vs. 15 patients requiring transfusions (p>0.01). In a multivariate analysis the duration of the Pringle maneuver (p>0.05) and the absence of preconditioning (p>0.05) were independent predictors for the occurrence of postoperative complications. CONCLUSIONS: IP protects against reperfusion injury, reduces the incidence of complications after hepatic resection under inflow occlusion and is simple to use in clinical practice

Statistically designed study of the variables and parameters of carbon dioxide equations of state

Carbon dioxide is used widely in enhanced oil recovery (EOR) processes to maximize the production of crude oil from aging and nearly depleted oil wells. Carbon dioxide also is encountered in many processes related to oil recovery. Accurate representations of the properties of carbon dioxide, and its mixtures with hydrocarbons, play a critical role in a number of enhanced oil recovery operations. One of the first tasks of this project was to select an equation of state to calculate the properties of carbon dioxide and its mixtures. The equations simplicity, accuracy, and reliability in representing phase behavior and thermodynamic properties of mixtures containing carbon dioxide with hydrocarbons at conditions relevant to enhanced oil recovery were taken into account. We also have determined the thermodynamic properties that are important to enhanced oil recovery and the ranges of temperature, pressure and composition that are important. We chose twelve equations of state for preliminary studies to be evaluated against these criteria. All of these equations were tested for pure carbon dioxide and eleven were tested for pure alkanes and their mixtures with carbon dioxide. Two equations, the ALS equation and the ESD equation, were selected for detailed statistical analysis. 54 refs., 41 figs., 36 tabs