Polytrauma induces increased expression of pyruvate kinase in neutrophils.

Polytrauma (PT) leads to systemic activation of polymorphonuclear neutrophils (PMNs). Organ damage commonly found in these patients is ascribed to respiratory bursts of activated PMNs. With the use of sodium dodecyl sulfate-polyacrylamide gel electrophoresis, PMN extracts from PT patients were found to contain a clear protein band not seen in control PMNs from healthy volunteers. This band was identified by amino acid sequencing and Western blotting as pyruvate kinase (PK). Enzymatic assays revealed a 600-fold increase in PK activity in PMNs of PT patients, with the highest levels occurring between the fifth and seventh posttraumatic day. In lymphocytes, no such increase was detectable. As PK is a major regulatory enzyme in glycolysis, glucose-dependent lactate production in PMNs from PT patients was assayed. These cells showed a higher glycolytic lactate production than controls. It was additionally demonstrated that acute activation of respiratory burst activity depends mainly on breakdown of glucose to lactate via the pentose-phosphate pathway and glycolysis. In PMNs from PT patients, this glucose-dependent respiratory burst activity was more than twofold higher than in controls. The increase in expression and activity of PK in PMNs from PT patients may contribute to the high glucose-dependent respiratory burst activity seen in these cells.

HSP70 expression in granulocytes and lymphocytes of patients with polytrauma: comparison with plasma glutamine.

Heat shock proteins (HSP's) are a set of conserved proteins which confer tolerance to stress. These proteins play a major role in the pathophysiology of infection and inflammation. Induction of HSP's before onset of sepsis is able to reduce or prevent organ damage and death. GLN is known to influence the expression of HSP70 in different cell types. In this work we tried to find out if there is an association between plasma GLN levels and HSP70 expression in immune cells. We investigated six polytraumatized patients and a control group of six healthy donors. HSP70 expression was investigated by western blot analysis and immune-histochemistry. We demonstrated that granulocytes and lymphocytes behave differently in the expression of HSP70 in polytraumatized patients. In healthy donors both lymphocytes and granulocytes showed a pronounced expression of HSP70. In contrast, most of the polytraumatized patients showed no HSP70 expression in granulocytes. In lymphocytes of these patients, however, a pronounced expression similar to that of healthy volunteers was observed. Plasma glutamine levels were reduced in all patients and at normal range in healthy donors. These results suggest that lymphocytes and granulocytes behave different when confronted with a reduction of plasma GLN levels.

Influence of heat shock on cell volume regulation: protection from hypertonic challenge in a human monocyte cell line.

Heat shock response provides cells with higher tolerance against a variety of insults such as heavy metals, reperfusion injury, and endotoxin. In addition, heat treatment is known to affect ion transport mechanisms associated with vital cellular processes, including cell volume regulation. However, there has been no reports to date of a heat shock effect on cellular volume regulation itself. The aim of our study was to investigate whether the heat shock response influences volume regulation of cells. Human promonocytic U937 cells display an increase in volume in response to osmotic shrinkage. This regulatory volume increase (RVI) is mediated mainly by ion antiporters. U937 cells exposed to a temperature of 45 degrees C for 10 min (heat shock) show an enhancement of RVI after hypertonic challenge compared with untreated cells. Also, heat-treated cells display a lower intracellular pH (pHi) than untreated cells; similar control mechanisms are believed to be involved in regulating both pHi and RVI. In agreement with this, heat-shocked cells demonstrated increased activity of an HCO3(-)-independent/DIDS-sensitive pHi down-regulator, postulated to be a Cl-/HCO3- exchange. We suggest that heat shock-mediated RVI enhancement is at least partially mediated by an increased Cl-/HCO3- exchange. Our results indicate that heat shock of U937 cells activates a hitherto unknown cytoprotective effect that may help cells to overcome hypertonic challenge.

Safety and efficacy of increasing dosages of glycyl-glutamine for total parenteral nutrition in polytrauma patients.

Supplementation of parenteral nutrition with glutamine (GLN) has been suggested to improve the efficacy of nutritional support by stimulating protein synthesis and improving immunocompetence. In the present study we investigated the impact of infusing the dipeptide glycyl-glutamine (GLY-GLN) at increasing dosages on plasma amino acid concentrations in patients with polytrauma. Nine polytraumatized patients were randomly assigned according their age and their trauma score to three experimental groups. Group 1 received 280, group II 450, and group III 570 mg GLY-GLN per kg body weight/day for a period of four days (3rd to 7th posttraumatic day), resulting in a maximum daily GLN administration (calculated for a 70 kg patient) of 14 g, 21 g and 28 g, respectively. Seven polytraumatized patients receiving the nutrition solution without GLY-GLN supplementation served as controls. All patients received total parenteral nutrition with an average amino acid administration of 1.1 g/kg/day and a total energy intake of 30 kcal/kg/day. GLY-GLN infusion did not evoke any side effects. In comparison with the control group, arterial plasma GLN concentrations increased significantly on day I after start of infusion in groups II and III, but remained raised throughout the study period only in group III (p < 0.003). Similarly, plasma GLY concentrations were also significantly raised in group III (p < 0.04). The maximum increase of plasma GLY was found on the second infusion day, after which plasma concentrations of GLY fell to concentrations even below those observed in the control group at the end of the study period. Excretion of GLY-GLN, GLN or GLY in the urine during the GLY-GLN infusions was negligible. We conclude from this first available dose finding study on glutamine-containing dipeptides that in polytraumatized patients infusion of 570 mg/kg/day of GLY-GLN (corresponding to 28 g glutamine or 40 g dipeptide/70 kg, respectively) is necessary to induce a sustained effect on plasma glutamine concentrations. No pathological accumulation of free glycine or of the dipeptide was seen with any of the three dosage steps of GLY-GLN. Thus, the administration of even high doses of GLY-GLN is feasible and safe in patients with polytrauma and is not associated with any relevant renal substrate loss.