Olive Oil-Based Lipid Emulsions Do Not Influence Platelet Receptor Expression in Comparison to Medium and Long Chain Triglycerides In vitro.

Lipid emulsions influence platelet aggregation and receptor expression. However, the effect on platelet function is not fully explained. Therefore, the aim of this study was to examine the influence of the lipids Lipofundin®, Lipidem® and ClinOleic® on surface expressions of P-selectin, GPIb and GPIIb/IIIa on platelets in vitro. Whole blood was incubated in two different concentrations (0.06 and 0.6 mg/ml) of LCT/MCT, n-3/LCT/MCT and LCT-MUFA for 30 min, followed by activation with TRAP-6 or ADP for flow-cytometric assay. Rates of P-selectin, GPIb and GPIIb/IIIa expression were analyzed. There was a significant increase in GPIIb/IIIa- and P-selectin-expression after incubation with LCT/MCT and n-3/LCT/MCT at the concentration of 0.6 mg/ml, without and after stimulation with TRAP-6 and ADP. GPIb was significantly decreased. Accordingly, LCT-MUFA had no effect on receptor expression of platelets in vitro. We demonstrated that LCT-MUFA did not activate receptor expression of platelets whereas LCT/MCT significantly increased platelet aggregation in vitro. This finding should be noted for parenteral nutrition of intensive care patients and, in the future, might provide further insight into the pathogenic pathways of acute thromboembolic events. However, prospectively designed clinical studies are needed to support our results.

Dependence of platelet function on underlying liver disease in orthotopic liver transplantation.

OBJECTIVE: The purpose of the present study was to explore the platelet function during the perioperative period of orthotopic liver transplantation (OLT) due to the underlying liver disease. METHODS: The blood coagulation parameters, platelet surface markers and the determination of platelet aggregation were analyzed in 34 patients who underwent OLT. Blood samples were drawn preoperatively, anhepatic, 10 min and 1 hour after reperfusion, 1 day, 3 and 7 days postoperatively. Conventional coagulation screens, thrombopoietin (TPO) serum levels, P-selectin, GPIIb/IIIa and GPIb binding sites on the surface of platelets as evaluated by flow cytometry and platelet aggregation response were measured. RESULTS: Coagulation factors, maximum aggregation and rate of aggregation were significantly different before transplantation due to the underlying liver disease. Further we found a markedly depressed GPIIb/IIIa and P-selectin expression and a reduced rate of aggregation in all patients throughout the study. In contrast maximum aggregation of platelets was restored on the third day after reperfusion without intergroup differences and almost comparable to healthy controls. An inverse correlation was found between peripheral platelet count pre-transplantation and peak TPO concentrations one weak post-transplantation. CONCLUSIONS: In the entire process of OLT, coagulation factors, maximum aggregation and rate of platelet aggregation depend on the surgical phases during transplantation and on the underlying liver disease. The data obtained in this study might contribute to a better understanding of the pathophysiology and assessment of bleeding risk in OLT.

Reduced post-operative neutrophil activation in liver transplant recipients suffering from post-hepatitic cirrhosis.

BACKGROUND: It has been supposed that liver transplant recipients with hepatitis C virus infection have a higher incidence of infectious complications after transplantation. This study was designed to investigate whether neutrophil function is immediately affected by liver transplantation. METHODS: Biochemical values, plasma levels of myeloperoxidase (MPO), hydrogen peroxide production of neutrophils and neutrophil-platelet complexes were analyzed in 32 patients who underwent liver transplantation and 20 healthy volunteers. RESULTS: MPO levels were significantly increased 24 h after reperfusion. In post-hepatitic patients levels were significantly lower three d up to one wk post-transplant than in patients due to other liver diseases. One wk post-operatively the respiratory burst activity following N-formyl-methionyl-leucylphenylalanine (fMLP) or (tumor necrosis factor-alpha) TNF-alpha/fMLP stimulation was depressed in post-hepatitic recipients. Respiratory burst stimulated with phorbol 12-myristate 13-acetate in these patients was increased one wk after transplantation. One d after transplantation the neutrophil-platelet complexes decreased significantly throughout the post-operative period. CONCLUSIONS: The results of this study suggest a reduced post-operative neutrophil activation in liver transplant recipients suffering from post-hepatitic cirrhosis compared to cirrhosis due to other causes. We hypothesized that neutrophil dysfunction in those patients depends on the underlying disease with an increased susceptibility to bacterial or fungal infections.

Renal transplantation normalized hydrogen peroxide production of neutrophils within the first day.

BACKGROUND: Hemodialysis patients are in a state of oxidant stress. In renal transplantation reactive oxygen species (ROS) are considered to be important factors of ischemia-reperfusion injury. Neutrophils produce ROS as part of the host defense against invading bacteria. This study was designed to investigate whether neutrophil function in hemodialysis patients is immediately affected by renal transplantation. METHODS: We evaluated the neutrophil respiratory burst and phagocytic activity in renal transplant patients with living-related donor (LRD) and cadaveric donor (CAD) grafts using flow cytometry techniques. Twenty patients (LRD = 6, CAD = 14) and 20 healthy volunteers were included in the study. Venous blood samples were drawn before anesthesia, 5 min before reperfusion, 1 h and 1, 3 and 7 days after reperfusion. RESULTS: Before surgery, a significant increase in hydrogen peroxide production in neutrophils was seen for both renal transplantation groups compared to healthy subjects. Within 24 h after reperfusion hydrogen peroxide production almost decreased to normal values. The phagocytic capacity of neutrophils was continuously depressed. There were no differences between the CAD and LRD groups. CONCLUSIONS: We found that the enhanced respiratory burst activity of patients with chronic renal failure decreased to normal values within 1 day following renal transplantation. Our results suggest that reduced respiratory burst activity resulting in a diminished risk of tissue damage by the uncontrolled production of ROS.

The role of portal vein clamping for cytokine release and neutrophils activity during liver resection and transplant.

OBJECTIVES: Uncontrolled release of cytokines has been linked to graft dysfunction or rejection and contributes to an increase in mortality and morbidity. We argue that temporary vascular clamping of the hepatic pedicle during major hepatic surgery is a potential stimulus for an excessive release of cytokines and the activity of neutrophils. MATERIALS AND METHODS: Thirty patients underwent partial liver resection or transplant. Samples were drawn preoperatively, immediately before portal vein clamping, at the early reperfusion period, and on days 1, 3, 5, and 7 after the operation. Central venous plasma concentrations of IL-6, IL-8, and TNF- a were compared to portal venous plasma. The influence of neutrophils on metabolic activity was measured by flow cytometry. RESULTS: In both patient groups, no significant differences in cytokine concentrations between central and portal venous plasma were found. However, significant differences of neutrophils activity were observed in patients undergoing partial liver resection compared to patients after transplant. CONCLUSION: Portal vein stasis induced by clamping the hepatic pedicle has no influence on the local release of IL-6, IL-8, and TNF-a. However, preoperatively increased plasma levels of TNF-a play a decisive role in the metabolic activity of neutrophils in patients with final-stage liver disease.

Ex vivo microvesicle formation after prolonged ischemia in renal transplantation.

INTRODUCTION: Patients with chronic renal failure suffer from dysfunction in coagulation. Kidney transplantation induces inflammatory reactions and thus activation of platelets. Activated platelets, in turn, form microvesicles by shedding. These microvesicles have been shown to have coagulant activities. Activated platelets in prolonged cold ischemia were associated with delayed graft function and inferior survival. We investigated ex vivo formation of microvesicles in kidney transplantation and the influence of cold graft storage on microvesicles. METHODS: 20 patients (47.4+/-10.6 years (mean+/-SD)) undergoing transplantation were included in the study after written informed consent. Dependent on cold preservation time of transplanted kidneys, recipients were allocated into two groups with 10.4+/-6.1 h (group 1) and 23.7+/-3.8 h (group 2) preservation time, respectively. Blood samples were drawn before anesthesia, 12 h, 2, 7 and 14 days after transplantation. To evaluate microvesicle release, samples were activated with thrombin-receptor-activating-peptide-6 (TRAP) or adenosine-di-phosphate. Microvesicles were counted as percentage of platelets smaller than a predetermined size in flow cytometry. RESULTS: Platelet derived ex vivo microvesicle formation was significantly higher up to 48 h after transplantation when stimulated with TRAP in group 1. Platelet count was significantly higher compared to baseline values in the short-term ischemia group but not with long-term ischemia. Creatinine was significantly lower at study end compared to baseline with no differences between both groups. CONCLUSIONS: Lower platelet microvesicle formation after ex vivo stimulation with TRAP was associated with longer graft ischemia time. This may be a sign of former activation of platelets which could influence graft function and survival.

Reduced P-selectin expression on circulating platelets after prolonged cold preservation in renal transplantation.

The uremic state in patients with terminal renal insufficiency is accompanied by a bleeding tendency connected with platelet dysfunction. Prolonged cold ischemia and inflammatory interactions between leukocytes, platelets and endothelial cells contribute to ischemia-/reperfusion (I/R) injury and may impair long-term graft survival. We evaluated the influence of the duration of cold preservation time on the expression of platelet GPIIb/IIIa and P-selectin and on the formation of leukocyte-platelet complexes after kidney transplantation. Fourteen patients undergoing kidney transplantation were divided into group I with long preservation time (26.6 +/- 1.9 h) and group II with short preservation time (8 +/- 6.1 h). Five venous blood samples (3 ml) were taken before induction of anesthesia, 12 h, 2, 7 and 14 d after transplantation. Surface expression of the GPIIb/IIIa, P-selectin and the percentage of platelet-granulocyte complexes were quantified by flow cytometry. Additionally blood from seven healthy volunteers was analyzed. GPIIb/IIIa and P-selectin expression on circulating platelets were significantly decreased in the long and the short-term graft preservation group compared with healthy volunteers. A significantly reduced P-selectin expression was found in the long-term preservation group compared with the short-term group. The percentage of platelet-granulocyte complexes also decreased in both preservation groups in the first 2 d after reperfusion and remained in this state in the long-term preservation group. Reduced expression of P-selectin on circulating platelets may be an indicator of I/R injury after prolonged kidney graft preservation.