Experimental research with synthetic copolymer-coated cardiopulmonary bypass circuits: inflammatory and thrombogenicity analysis

This study aimed to assess complement system activation and index of thrombogenicity and platelet aggregation between synthetic copolymer-coated cardiopulmonary bypass (CPB) circuit and conventional CPB circuit. Twenty-six pigs were equally divided into two groups--the conventional group and the coated group. They were placed on CPB for 90 min, and blood samples were collected at three different time points (T0, right before CPB establishment; T1, 45 min after starting CPB; and T2, 90 min after starting CPB) to measure total count of inflammatory cells (leukocytes, neutrophils, lymphocytes, and platelets) and serum levels of fraction C3 of complement system. Upon completion of the 90-min CPB, fragments of different compartments of the CPB circuit were taken for assessing index of thrombogenicity and platelet aggregation. There were no differences between both groups regarding total count of leukocytes, neutrophils, and lymphocytes; however, there was a lower count of platelets at T2 in the coated group (P = 0.020). The serum level of fraction C3 was lower in the coated group at T1 (P = 0.020) and T2 (P = 0.017). Higher index of thrombogenicity and platelet aggregation were detected in the conventional group (77% of the animals within the conventional group) than in the coated group (46% of the animals within the coated group). In conclusion, in heart surgery requiring CPB, the use of synthetic copolymer-coated CPB circuit may be useful to reduce complement system activation, as well as attenuating index of thrombogenicity and platelet aggregation.     

Effects of epsilon-aminocaproic acid and aprotinin on leukocyte-platelet adhesion in patients undergoing cardiac surgery

BACKGROUND: The administration of aprotinin during cardiopulmonary bypass (CPB) is hypothesized to decrease activation of leukocytes and platelets and possibly reduce their adhesion. Although epsilon-aminocaproic acid (EACA) shares the ability of aprotinin to inhibit excessive plasmin activity after CPB, its effect on leukocyte and platelet activation and leukocyte-platelet (heterotypic) adhesion is largely unknown. This study was performed to determine the relative effectiveness of the antifibrinolytics, aprotinin and EACA, at reducing leukocyte and platelet activation and leukocyte-platelet conjugate formation in patients undergoing CPB. METHODS: Thirty-six patients scheduled to undergo cardiac surgery with CPB were randomized in a double-blind fashion to receive EACA, aprotinin, or saline (placebo). Markers of plasmin activity (D-dimer concentrations), platelet activation (CD62P), leukocyte activation (CD11b), and leukocyte-platelet adhesion (monocyte- and neutrophil-platelet conjugates) were measured before, during, and after CPB. RESULTS: Platelet CD62P (P-selectin), monocyte CD11b, and monocyte-platelet conjugates were all significantly increased (compared with baseline) in the saline group during and after CPB. Despite equivalent reductions in D-dimer formation in patients receiving EACA (P < 0.0001) and aprotinin (P < 0.0001), decreases in platelet CD62P and monocyte CD11b expression were incomplete (not significantly different from saline control). In contrast, peak monocyte-platelet conjugate formation was significantly reduced by both EACA (P = 0.026) and aprotinin (P = 0.039) immediately after CPB. CONCLUSIONS: EACA seems to be as effective as aprotinin at reducing peak monocyte-platelet adhesion after CPB. Furthermore, inhibition of excessive plasmin activity seems to influence monocyte-platelet adhesion. The findings suggest that monocyte-platelet conjugate formation may be a useful marker of monocyte and platelet activation in this clinical setting.     

Effects of ε-Aminocaproic Acid and Aprotinin on Leukocyte-Platelet Adhesion in Patients Undergoing Cardiac Surgery

Background: The administration of aprotinin during cardiopulmonary bypass (CPB) is hypothesized to decrease activation of leukocytes and platelets and possibly reduce their adhesion. Although [epsilon]-aminocaproic acid (EACA) shares the ability of aprotinin to inhibit excessive plasmin activity after CPB, its effect on leukocyte and platelet activation and leukocyte-platelet (heterotypic) adhesion is largely unknown. This study was performed to determine the relative effectiveness of the antifibrinolytics, aprotinin and EACA, at reducing leukocyte and platelet activation and leukocyte-platelet conjugate formation in patients undergoing CPB.

Methods: Thirty-six patients scheduled to undergo cardiac surgery with CPB were randomized in a double-blind fashion to receive EACA, aprotinin, or saline (placebo). Markers of plasmin activity (D-dimer concentrations), platelet activation (CD62P), leukocyte activation (CD11b), and leukocyte-platelet adhesion (monocyte- and neutrophil-platelet conjugates) were measured before, during, and after CPB.

Results: Platelet CD62P (P-selectin), monocyte CD11b, and monocyte-platelet conjugates were all significantly increased (compared with baseline) in the saline group during and after CPB. Despite equivalent reductions in D-dimer formation in patients receiving EACA (P < 0.0001) and aprotinin (P < 0.0001), decreases in platelet CD62P and monocyte CD11b expression were incomplete (not significantly different from saline control). In contrast, peak monocyte-platelet conjugate formation was significantly reduced by both EACA (P = 0.026) and aprotinin (P = 0.039) immediately after CPB.     

Compstatin, a peptide inhibitor of C3, prolongs survival of ex vivo perfused pig xenografts

Fiane AE, Mollnes TE, Videm V, Hovig T, Høgåsen K, Mellbye OJ, Spruce L, Moore WT, Sahu A, Lambris JD. Compstatin, a peptide inhibitor of C3, prolongs survival of ex vivo perfused xenografts. Xenotransplantation 1999; 6: 000-000 ©Munksgaard, Copenhagen Compstatin, a newly described C3-binding peptide, inhibits complement activation by blocking C3 convertase-mediated cleavage of C3. As the complement activation is an essential part of the rejection reaction, we evaluated the ability of Compstatin to delay or prevent hyperacute rejection in an ex vivo xenograft model. Porcine kidneys were perfused with fresh human blood containing either Compstatin (n=6) or a control agent (n=6). Graft survival and activation of complement, leukocytes and platelets both in the fluid phase and in the tissue were examined. The survival of the Compstatin-perfused kidneys (median, 380 min) was significantly (P=0.0036) longer than that of the controls (median, 90 min). The classical complement pathway (C1rs-C1inhibitor and C4bc) was significantly and equally activated in both groups during the first 60 min. C3 activation products increased fivefold and terminal complement complex eightfold in the control group, but no increase occurred in the Compstatin group during this period. Immunohistochemistry showed less C3 and fibrin deposition and immuno-electron microscopy showed less terminal SC5b-9 complement complex deposition in the Compstatin group. A significant change in total white cells, neutrophils, myeloperoxidase, and expression of the surface activation markers CD11b (CR3) and CD35 (CR1) and CD62 L ( l -selectin) was observed in both groups. Leukocyte activation was lower in the Compstatin group but the difference was not statistically significant. There were no differences in platelet counts, thrombospondin, soluble P-selectin or β-thromboglobulin between the groups. We conclude that Compstatin prolongs graft survival and suggest that it may be a useful agent for attenuating hyperacute rejection by inhibiting C3 and thus terminal complement pathway activation.     

咪达唑仑对冠心病患者体外血小板活化反应的影响

目的 评价咪达唑仑对冠心病患者体外血小板活化反应的影响.方法 分别抽取10名健康志愿者及40例冠心病患者肱静脉血样5 ml,抗凝离心后得到富含血小板血浆(PRP).实验Ⅰ:每份PRP 1 ml,10份健康志愿者PRP作为正常对照组(ⅠC组,n=10),40份冠心病患者PRP随机分为4组(n:10):ⅠM0组、ⅠM1组、ⅠM2组和ⅠM3组Ⅰ.C组和ⅠM0组不加入咪达唑仑,ⅠM1组、ⅠM2组、ⅠM3组加入咪达唑仑,其终浓度分别为100、200、400ng/ml,孵育3 min,检测血小板聚集率.实验Ⅱ:将剩余PRP进一步离心后得到洗涤血小板(WP),每份WP 1 ml,10份健康志愿者WP作为正常对照组(ⅡC组),40份冠心病患者WP随机分为4组(n=10):ⅡM0组、ⅡM1组、ⅡM2组和ⅡM3组.ⅡC组和ⅡM0组不加入咪达唑仑,ⅡM1组、ⅡM2组、Ⅱ3组加入咪达唑仑,其终浓度分别为100、200、400 ng/ml,孵育3 min,采用竞争酶联免疫法检测血小板环磷酸腺苷(cAMP)和血栓烷B2(TXB2)的含量.结果 与ⅠC组比较,ⅠM0组血小板聚集率升高(P<0.01);与ⅠM1组比较,ⅠM2组和ⅠM3组血小板聚集率降低(P<0.01),ⅠM1组差异无统计学意义(P>0.05).与ⅡC组比较,ⅡM0组血小板cAMP含量降低、TXB2含量升高(P<0.01);与ⅠM0组比较,ⅡM1组和ⅡM3组血小板cAMP含量升高(P<0.05或0.01),,TXB2含量降低(P<0.01),ⅠM1组差异无统计学意义(P>0.05).结论 咪达唑仑200、400 ng/ml通过提高血小板cAMP水平,抑制其TXA2生成,可降低冠心病患者血小板的活化程度.     

Adverse outcome of human islet-allogeneic blood interaction

BACKGROUND: A report of inflammatory damage when islets come into contact with allogeneic blood prompted us to confirm the finding. METHODS: Fresh handpicked human islets were incubated in blood group matched, nonsensitized allogeneic blood. Destruction was quantified by assaying the supernatants for proinsulin release and by blood clot histology. The effect on global hemostasis was assessed by thromboelastography (TEG), and heparin-bonded tubing was used to assess the effect on blood cellular counts. In separate experiments, islets were incubated in allogeneic blood with heparin or Reopro (monoclonal anti-GpIIbIIIa). Islets were also incubated in serum, and cryosections were stained for C1q, C4, C3, C5b-9, immunoglobulin (Ig)M, and IgG binding using immunohistochemistry. RESULTS: Histologic assessment showed severe destruction in 37% of islets in contact with allogeneic blood versus none in controls and a sevenfold increase in proinsulin release from controls (n = 6)(P < 0.005). TEG (n = 11) showed accelerated coagulation in the presence of islets (P < 0.001). Analysis of blood cellular counts (n = 3) showed consumption of platelets, neutrophils, and monocytes in the presence of islets (P < 0.001). Inhibition of coagulation with heparin (n = 3) or inhibition of platelet aggregation with Reopro (n = 3), separately or together (n = 3), did not make a substantial improvement in the destruction in terms of histology or proinsulin release. Immunohistochemical staining (n = 4) revealed C1q, C4, C3, and C5b-9 deposition along with IgG binding. IgM binding was weak if anything. CONCLUSION: This study confirms and extends the finding that human islet-allogeneic blood interaction results in significant destruction of islet tissue with activation of the coagulation cascade and platelet, neutrophil, and monocyte consumption. There was evidence for activation of complement by the classical pathway along with IgG binding.     

Selective blockade of membrane attack complex formation during simulated extracorporeal circulation inhibits platelet but not leukocyte activation.

OBJECTIVE: Complement activation is induced by cardiopulmonary bypass, and previous work found that late complement components (C5a, C5b-9) contribute to neutrophil and platelet activation during bypass. In the present study, we blocked C5b-9 formation during extracorporeal recirculation of whole blood to assess whether the membrane attack complex was responsible for both platelet and leukocyte activation. METHODS: In a simulated extracorporeal model that activates complement (C3a and sC5b-9), platelets (CD62P expression, leukocyte-platelet conjugate formation), and leukocytes (increased CD11b expression and neutrophil elastase), we examined an anti-human C8 monoclonal antibody that inhibits C5b-9 generation for its effects on cellular activation. RESULTS: Anti-C8 significantly inhibited sC5b-9 formation but did not block C3a generation. Anti-C8 also significantly inhibited the increase in platelet CD62P and monocyte-platelet conjugate formation seen with control circulation. Moreover, compared with control circulation, in which the number of circulating platelets fell by 45%, addition of anti-C8 completely preserved platelet counts. In contrast to blockade of both C5a and sC5b-9 during simulated extracorporeal circulation, neutrophil activation was not inhibited by anti-C8. However, circulating neutrophil and monocyte counts were preserved by addition of anti-C8 to the extracorporeal circuit. CONCLUSIONS: The membrane attack complex, C5b-9, is the major complement determinant of platelet activation during extracorporeal circulation, whereas C5b-9 blockade has little effect on neutrophil activation. These data also suggest a role for platelet activation or C5b-9 (or both) in the loss of monocytes and neutrophils to the extracorporeal circuit.     

Synthetic protein treated versus heparin coated cardiopulmonary bypass surfaces: similar clinical results and minor biochemical differences.

OBJECTIVE: Complications associated with cardiopulmonary bypass (CPB) have gained more attention due to increased interest in coronary artery bypass grafting without CPB. The impact of heparin coating of CPB circuits has been discussed controversially. The present study examines if the treatment of the oxygenator surface with a synthetic protein may serve as an alternative to a completely heparin coated circuit. METHODS: Fifty-eight patients undergoing coronary artery bypass grafting with CPB were randomly assigned to completely heparin coated circuits or synthetic protein treated oxygenators in a double blind protocol, focussing on the inflammatory reaction resulting in membrane damage, coagulation changes and markers of cerebral injury or dysfunction. Treatment groups did not differ as to preoperative demographics, and intraoperative clinical data. Patients with any neurologic disease or risk factors for cerebral dysfunction were not included in the study. RESULTS: Postoperative clinical data did not differ between groups. Both surface treatments resulted in similar coagulation activation, hyperfibrinolysis and disseminated intravascular coagulation. Platelet count displayed a difference in favour of the heparin coated group (P = 0.029). Increased leukocyte activation reflected by rising myeloperoxidase concentrations on CPB was present in both synthetic protein and heparin coating groups. Interleukins 6 and 8 reacted similarly, but interleukin 8 increased significantly more (P = 0.0061) at the end of surgery in patients treated with protein treated oxygenators. The same pattern was observed for complement activation as determined by total complement complex (P = 0.006). Both surface changes resulted in moderately increased S-100B protein and neuron specific enolase, without difference between groups. Both markers did not reach concentrations associated with clinical manifestation of cerebral injury. CONCLUSIONS: These results in routine patients with short bypass time, imply that protein treated oxygenators are associated with a limited increase of biochemical markers similar to heparin coating. However, significantly lower interleukin 8 release and complement activation can be achieved by heparin coating. The protein treatment is a standard feature of the oxygenator examined in both groups. It is not associated with additional cost and therefore appropriate for use in routine patients.     

Inhibition of systemic inflammatory response with sodium nitroprusside in open heart surgery

BACKGROUND: A nitric oxide donor, sodium nitroprusside has been reported to reduce the inflammatory response during cardiopulmonary bypass (CPB). To investigate this, a double-blind and prospective study was conducted. METHODS: Twenty patients with multi vessel coronary disease were randomly chosen to form study (SNP) and control groups. In the SNP group, 0.5 microg/kg/min sodium nitroprusside were administered for 20 min right after the release of the aortic crossclamp. Mac-1 (CD11b/CD18) leukocyte adhesion molecule expressions, interleukin-6 levels were measured from radial artery blood as well as leukocyte and platelet counts in both groups at 6 different time points: a) before anesthesia, b) after heparin administration, c) after aortic crossclamp release, d) after protamine administration, e) 3 hours after the termination of CPB, f) 24 hours after the termination of CPB. RESULTS: The increase in Mac-1 expressions were not different between the two groups at any time point except the measurements after the administration of protamine. At this time point, Mac-1 expressions were not different between the groups (99.8+/-30.7 vs 134.6+/-95.1%, p=0.076), but higher when compared with the preinduction levels. IL-6 levels for SNP and control groups was 89+/-43 and 215+/-131 pg/dL, respectively (p=0.016) 3 hours after the termination of CPB. Twenty-four hours after the termination of CPB, IL-6 levels were still significantly higher in the control group (47+/-27 vs 111+/-68 pg/dL, p=0.039). Leukocyte and platelet counts were not different at any time point between the groups. CONCLUSIONS: Systemic inflammatory response in patients undergoing CPB can be reduced to a certain level with sodium nitroprusside, especially the activation of vascular endothelial cells can be inhibited, but activation of leukocytes still takes place.     

sCR1sLe ameliorates ischemia/reperfusion injury in experimental lung transplantation

BACKGROUND: The nonspecific immune response with activation of the complement system and polymorphonuclear leukocytes is important for the mediation of reperfusion injury after lung transplantation. In this study, we investigated the combined blockade of the complement system and leukocyte adhesion by a novel drug combining soluble complement receptor type 1 (sCR1, CD35) with the selectin ligand sialyl Lewis X (sLe(X), CD15s) synthesized to sCR1sLe(X). Both sCR1 and sCR1sLe(X) were supplied by AVANT Immunotherapeutics, Inc, Needham, Massachusetts. METHODS: Orthotopic allogeneic single left lung transplantation was performed in male rats (Brown Norway to Fischer F344; n = 5 in all groups) after a total ischemic time of 20 hours. Recipients received either no specific treatment (control) or administration of sCR1 (10 mg/kg) or sCR1sLe(X) (10 mg/kg) 15 minutes before reperfusion by intracardiac injection. Twenty-four hours after reperfusion, the native contralateral lung was occluded to assess gas exchange of the graft only. In additional animals (5 per group), lung tissue was frozen 24 hours after reperfusion and assessed for myeloperoxidase activity as a measurement of neutrophil migration into the graft and thiobarbituric acid reactive substances to quantify lipid peroxidation. RESULTS: Graft function as assessed by arterial PO (2) in recipients treated with sCR1sLeX was superior not only to that of controls (383 +/- 53 vs 56 +/- 7 mm Hg, P =. 000095) but also to that of animals treated with sCR1 (243 +/- 45 mm Hg, P =.031). This improvement was confirmed by significant reduction of neutrophil migration (0.33 +/- 0.05 vs control, 1.0 +/- 0.09 DeltaOD/mg/min, P =.0000024) and lipid peroxidation (6.2 +/- 0. 38 vs control, 10.6 +/- 0.54 pmol/g, P =.00021). CONCLUSIONS: Our data indicate that combined inhibition of complement activation and leukocyte adhesion with sCR1sLe(X) reduces reperfusion injury significantly and that both mechanisms are effectively inhibited in this model.     

Influence of PMEA-coated bypass circuits on perioperative inflammatory response

BACKGROUND: Poly(2-methoxyethylacrylate) (PMEA) is a new coating material, and several experimental studies have revealed excellent biocompatibility of PMEA-coated cardiopulmonary bypass circuits. The clinical utility of the PMEA-coated circuits was compared with that of uncoated circuits, focusing on perioperative inflammatory response. METHODS: Twenty-two patients were randomized to PMEA-coated (group P; Capiox RX25; n = 11) or uncoated (group U; Capiox SX10; n = 11) circuit group, and underwent coronary artery bypass grafting and/or valve operations. The following markers, as well as clinical outcomes, were analyzed perioperatively: (a) complement activation by C3a (including C3a-desArg) concentrations; (b) leukocyte activation by polymorphonuclear-elastase concentrations; (c) acute phase inflammatory response by interleukin-6 concentrations; and (d) platelet preservation by number of platelets. RESULTS: The maximal values of C3a and polymorphonuclear-elastase were significantly lower in group P than in group U. The intergroup difference of interleukin-6 was not significant. Although preservation of platelets was significantly better in group P until 1 hour after initiating cardiopulmonary bypass, no significant intergroup difference was observed thereafter. The duration of postoperative mechanical ventilation revealed no significant intergroup difference. CONCLUSIONS: The PMEA-coated circuits exhibited better suppression of perioperative complement and leukocyte activation than the uncoated circuits. In addition, the price of the PMEA-coated circuits is the same as that of the uncoated circuits. Therefore, we judged that the clinical utility of the PMEA-coated circuits is superior to those of the uncoated circuits.     

Changes in Platelet, Granulocyte, and Complement Activation During Cardiopulmonary Bypass Using Heparin-coated Equipment

Abstract: The effects of heparin-coated cardiopulmonary bypass (CPB) systems on platelet, granulocyte, and complement activation were investigated during cardiopulmonary bypass. Thirty patients underwent coronary artery bypass surgery with a heparin-coated (Carmeda Bio-Active Surface, CBAS, Medtronic, U.S.A.) CPB system (HC group, n = 10), a heparin-coated oxygenator and uncoated CPB circuit (HO group, n = 10), or an uncoated system (UC group, n = 10). In the HO group, plasma C3a (1667 ± 632 ng/ml) and C4a (1088 ± 319 ng/ml) concentrations were significantly (p < 0.05) lower than in the UC group (2846 ± 1045 ng/ml and 1494 ± 480 ng/ml, respectively) 10 min after the administration of protamine, but there were no significant differences in the platelet or granulocyte counts. In the HC group, granulocyte elastase concentrations 120 min after the onset of CPB (365 ± 177 μg/L) and 10 min after the administration of protamine (676 ± 314 μg/L) were significantly (p < 0.05) lower than in the other 2 groups (820 ± 341 and 893 ± 303 μg/L and 1365 ± 595 and 1,258 ± 622 μg/L). In addition, the increase in the plasma C3a concentration in the HC group 60 (p < 0.05) and 120 min after the onset of CPB (p < 0.05) was significantly less than in the other 2 groups. The C3a and C4a concentrations 10 min after the administration of protamine were significantly (p < 0.005 and p < 0.05) less in the HC group than in the UC group. Platelet counts 10 min after the administration of protamine were significantly higher (p < 0.05) and plasma β-throm-boglobulin concentrations during CPB were significantly lower in the HC group than in the other 2 groups 5 (p < 0.05), 60, and 120 min (p < 0.005) after the onset of CPB. Postoperative blood loss during the first 12 h in the HC group was significantly (p < 0.05) less than that in the UC group. The heparin-coated oxygenator and uncoated CPB circuit reduced complement activation but demonstrated no significant effects on the platelet and granulocyte systems. However, the heparin-coated CPB circuit (with all components making blood contact) reduced platelet, granulocyte, and complement activation and significantly reduced postoperative blood loss. Therefore, heparin coating of CPB systems improves biocompatibility.     

Phosphorylcholine coating of extracorporeal circuits provides natural protection against blood activation by the material surface.

OBJECTIVE: The aim of this study is to evaluate the use of a new coating, mimicking the outer cell membrane, in paediatric cardiac surgery. METHODS: Two groups of ten patients with a body weight below 8 kg, undergoing elective cardiac operations for different congenital anomalies, were prospectively enrolled in this study. In one group the whole extracorporeal circuit, including the cannulas, was coated with phosphorylcholine (PC). In the second group the same circuit was used without coating. Platelet activation (thromboxane B2 (TXB2), beta-thromboglobulin (betaTG)), activation of the coagulation system (F1+2), leukocyte activation (CD11b/CD18) and terminal complement activation (TCC) were analyzed pre-cardiopulmonary bypass (CPB), at 15, 60 min of CPB, at the end of CPB, 20 min post CPB and at postoperative day 1 and 6. RESULTS: No statistical differences were found for F1+2 and CD11b/CD18. After onset of CPB mean levels of TCC remained stable in the PC group whereas an increase was observed in the control group. During CPB betaTG values in both groups increased to a maximum at the end of CPB. Within groups the increase in betaTG levels during CPB was statistically significant (P<0.05) from baseline in the control group starting from 60 min of CPB whereas no statistical difference was observed in the PC group. After the start of CPB TXB2 mean levels increased to 405+/-249 pg/ml in the PC group vs. 535+/-224 pg/ml in the control group. After this initial increase there was a small decline in the PC group with further increase. This was in contrast to the control group were TXB2 levels further increased up to a mean of 718+/-333 pg/ml at the end of CPB (P=0.016). CONCLUSIONS: Phosphorylcholine coating had a favourable effect on blood platelets, which is most obvious after studying the changes during cardiopulmonary bypass. A steady increase of TXB2 and betaTG was observed in the control group, whereas plateau formation was observed in the phosphorylcholine group. Clinically, this effect may contribute to reduced blood loss and less thromboembolic complications. Complement activation is lower in the coated group.     

Platelet function profiles in patients with type 2 diabetes and coronary artery disease on combined aspirin and clopidogrel treatment

To assess platelet function profiles in diabetic and nondiabetic patients on aspirin and clopidogrel therapy, two patient populations were included to investigate the 1) acute effects of a 300-mg clopidogrel loading dose (group 1, n = 52) and 2) long-term effects of clopidogrel (group 2, n = 120) on platelet function in diabetic compared with nondiabetic patients already on aspirin treatment. Patients were stratified according to the presence of type 2 diabetes. Platelet aggregation was assessed using light transmittance aggregometry (groups 1 and 2). Platelet activation (P-selectin expression and PAC-1 binding) was determined using whole-blood flow cytometry (group 2). Clopidogrel response was also assessed. In group 1, platelet aggregation was significantly increased in diabetic (n = 16) compared with nondiabetic (n = 36) patients at baseline and up to 24 h following a 300-mg loading dose (P = 0.005). In group 2, platelet aggregation and activation were increased in diabetic (n = 60) compared with nondiabetic (n = 60) subjects (P < 0.05 for all platelet function assays). Diabetic subjects had a higher number of clopidogrel nonresponders (P = 0.04). Diabetic patients have increased platelet reactivity compared with nondiabetic subjects on combined aspirin and clopidogrel treatment. Reduced sensitivity to antiplatelet drugs may contribute to the increased atherothombotic risk in diabetic patients.     

Antithrombin can modulate coagulation, cytokine production, and expression of adhesion molecules in abdominal aortic aneurysm repair surgery

We investigated the effects of antithrombin on coagulation, fibrinolysis, and production of cytokines and adhesion molecules in abdominal aortic aneurysm repair surgery. Sixteen patients for Y-shaped graft replacement of abdominal aortic aneurysm were divided into an antithrombin group and a control group. In the antithrombin group, 3000 U antithrombin was infused over 30 min before heparin administration and 24 h later. White blood cell counts, platelet counts, prothrombin time ratio, and serum concentrations of antithrombin, polymorphonuclear leukocyte elastase, interleukin (IL)-1beta, IL-6, IL-8, tumor necrosis factor-alpha, and adhesion molecules, and variables of coagulation and fibrinolysis were measured before surgery, at the end of surgery, and 1 and 2 days after surgery. The antithrombin concentration decreased in the control group, whereas it increased in the antithrombin group with significant differences between the groups. Prothrombin time ratio, concentrations of d-dimer, thrombin-antithrombin complex, and intercellular adhesion molecule-1 increased only in the control group and polymorphonuclear leukocyte elastase, IL-6, tumor necrosis factor-alpha, and vascular cell adhesion molecule-1 increased in both groups. They were significantly less in the antithrombin group except for intercellular adhesion molecule-1. In conclusion, antithrombin could decrease hypercoagulation and inflammatory activation during abdominal aortic aneurysm surgery, which may decrease adverse events.     

Leukocyte depleting filter attenuates myocardial injury during elective coronary artery bypass surgery

BACKGROUND: Ischemia-reperfusion injury secondary to leukocyte activation has been widely recognized as one of the most relevant mechanism leading to postoperative organ dysfunction occurring after a period of ischemia. The aim of the present study was to evaluate in a prospective, randomized study, the value of leukocyte depleting filter in patients undergoing elective coronary artery bypass surgery. METHODS: Twenty patients scheduled for elective on-pump coronary artery bypass surgery were randomized to undergo cardiopulmonary bypass either with a leukocyte depleting filter incorporated in the extracorporeal circulation arterial line or without a filter. RESULTS: The main finding of this study was the significantly lower postoperative concentrations of cardiac troponin I in the leukocyte filter group (Tests of between-subjects effects: p = 0.024). There were also slightly better cardiac indices in the leukocyte filter group. A larger amount of blood units was infused intra- and postoperatively in patients undergoing cardiopulmonary bypass with leukocyte filtration (median, 600 [IQR, 0-1200] vs. 0 [IQR, 0-600], p = 0.08). Two patients in the leukocyte filter group underwent reoperation for bleeding but none in the control group (p = 0.48). Intra-and postoperative platelet count was lower in the leukocyte filter group (Tests of between-subjects effects: p = 0.08). Despite a significant increased concentration of C-reactive protein on the first postoperative day in the control group (p = 0.029), repeated-measures analysis failed to show any significant increase during the study period (p = 0.33). CONCLUSIONS: The results of this study suggest a myocardial protective effect of leukocyte filter in the setting of elective coronary artery bypass surgery.     

The GP IIb/IIIa inhibitor abciximab (ReoPro) decreases activation and interaction of platelets and leukocytes during in vitro cardiopulmonary bypass simulation.

OBJECTIVE: Cardiopulmonary bypass (CPB) induces a systemic inflammatory response and increases expression of the platelet activation marker P-selectin which mediates binding of platelets to leukocytes. Inhibition of the platelet GP IIb/IIIa receptor during CPB has been shown to protect platelets without increasing bleeding complications and is assumed to reduce the inflammatory response. The aim of this study was to investigate the effect of the GP IIb/IIIa inhibitor abciximab (ReoPro) on the function and interaction of platelets and leukocytes during experimental CPB. METHODS: Heparinized (3 U/ml) fresh whole blood of healthy volunteers was treated before continuous in vitro circulation in a well established CPB model with 3.2 microg/ml abciximab (n=6) or left untreated as control (n=6). Measurements were made before (baseline) and after 30 and 60 min of circulation and comprised: percentage of platelets expressing P-selectin and percentage of platelet-bound leukocytes (flow cytometry), release of the leukocyte activation marker PMN-elastase (ELISA), and platelet and leukocyte counts. RESULTS: Abciximab almost completely prevented a CPB-induced increase of platelet P-selectin and platelet-leukocyte binding after 30 and 60 min of circulation, and significantly inhibited release of PMN-elastase after 30 min of circulation. Furthermore, abciximab significantly inhibited a CPB-induced decrease of platelet and leukocyte counts. CONCLUSIONS: Abciximab inhibits CPB-induced activation, interaction and consumption of platelets and leukocytes in vitro. GP IIb/IIIa inhibition should be considered as a promising approach not only to conserve platelet function but also to inhibit pro-inflammatory events during CPB in vivo.     

The effects of methylprednisolone on complement, immunoglobulins and pulmonary neutrophil sequestration during cardiopulmonary bypass.

In this study, the authors administered high dose (30 mg/kg body weight i.v.) methylprednisolone before cardiopulmonary bypass to observe the effects on complement, immunoglobulins and pulmonary neutrophil sequestration. Fifty patients undergoing valve replacements were included in this study. Patients were divided into two groups: group I (20 patients) served as control and did not receive methylprednisolone, group II (30 patients) received methylprednisolone. Blood samples for complements (C3c and C4) were taken, before cardiopulmonary bypass, at 5, 10 and 30 min intervals from the end of cardiopulmonary bypass, after reversal of heparin with protamine infusion, and after skin closure. Blood samples for immunoglobulins were taken before cardiopulmonary bypass, 30 min after onset of cardiopulmonary bypass and after skin closure. After onset of cardiopulmonary bypass, all C3c and C4 levels decreased in both groups. There was a significant decrease in C4 levels at end of cardiopulmonary bypass and after protamine infusion in group I compared with group II (P < 0.05). C3c levels in group I decreased significantly compared with group II after 30 min of cardiopulmonary bypass and after protamine infusion (P < 0.05). All immunoglobulin (IgG, IgM, IgA) levels were decreased in both groups, but the decrease in IgG was statistically significant after skin closure in group I compared with group II (P < 0.05). Pulmonary neutrophil sequestration was higher in the control group compared with the methyl-prednisolone group (P < 0.05). In conclusion, methylprednisolone administration before cardiopulmonary bypass may prevent the harmful effects of complement activation, immunoglobulin denaturation and neutrophil sequestration in the pulmonary capillary system.     

Transplantation of the spleen: effect of splenic allograft in human multivisceral transplantation

OBJECTIVES: To describe the effect of the splenic allograft in human multivisceral transplantation. SUMMARY BACKGROUND DATA: We performed transplants of the spleen as part of a multivisceral graft in an attempt to decrease both the risk of infection from an asplenic state and the risk of rejection by a possible tolerogenic effect. To our knowledge, this is the first report of human splenic transplantation in a large series. METHODS: All primary multivisceral recipients who received a donor spleen (N = 60) were compared with those who did not receive a spleen (N = 81). RESULTS: Thirty-five of 60 (58%) are alive in the spleen group, and 39 of 81 (48%) are alive in control group (P = 0.98). In univariate analysis, splenic recipients showed superiority in freedom-from-any rejection (P = 0.02) and freedom-from-moderate or severe rejection (P = 0.007). No significant differences were observed in analyses of infectious complications between the spleen and control groups. Both platelet and leukocyte counts became normal in splenic patients, whereas these counts were significantly increased in nonsplenic recipients. Observed incidence of graft versus host disease (GVHD) was 8.25% (5 of 60) in the spleen group and 6.2% (5 of 81) in the control group (P = 0.70). Increased incidence of autoimmune hemolysis was observed in the spleen group. CONCLUSIONS: Allograft spleen can be transplanted within a multivisceral graft without significantly increasing the risk of GVHD. The allogenic spleen seems to show a protective effect on small bowel rejection. Further investigation with longitudinal follow-up is required to precisely determine the immunologic and hematologic effects of the allograft spleen.