Biomedical subjects

T E Mollnes

Publications and source records attributed to T E Mollnes.

At least 73 records · Page 4Linked to original sources

PubMed1997

Attenuation of changes in leukocyte surface markers and complement activation with heparin-coated cardiopulmonary bypass.

BACKGROUND: The inflammatory response induced by cardiopulmonary bypass can result in severe organ dysfunction in some patients. This postperfusion response is caused mainly by contact between blood and the foreign surface of the cardiopulmonary bypass equipment and includes adhesion of leukocytes to vascular endothelium, which precedes a series of events that mediate inflammatory damage to tissues. METHODS: Low-risk patients accepted for coronary artery bypass grafting were randomized to operation with the cardiopulmonary bypass surface either completely heparin coated (Duraflo II) or uncoated. There were 12 patients in each group. Blood plasma sampled during cardiopulmonary bypass was analyzed for complement activation (C3bc and terminal SC5b-9 complement complex) and neutrophil activation (lactoferrin and myeloperoxidase). In addition, neutrophils, monocytes, and platelets were counted, and the expression of surface markers on the neutrophils and monocytes (complement receptor [CR] 1, CR3, CR4, and L-selectin) and on the platelets (P-selectin and CD41) was quantified with flow cytometry. RESULTS: Clinical and surgical results were similar in both groups. In the group with the heparin-coated surface, the formation of the terminal SC5b-9 complement complex was significantly reduced, and the counts of circulating leukocytes and platelets were significantly less reduced initially but were higher at the end of cardiopulmonary bypass compared with baseline. Also, the expression of CR1, CR3, and CR4 was significantly less upregulated and the L-selectin, significantly less downregulated on monocytes and neutrophils. CONCLUSIONS: We conclude that heparin coating reduces complement activation and attenuates the leukocyte integrin and selectin response that occurs when uncoated circuits are used.

Antigens, Surface↗

PubMed1997

Both plasma- and leukocyte-associated C5a are essential for assessment of C5a generation in vivo.

BACKGROUND: Measurement of C5a in plasma is hampered by the rapid clearance of C5a as a result of cell binding. Therefore, an assessment of whether cell-bound C5a might better reflect C5a generation in vivo is essential. METHODS: We quantified plasma and leukocyte-bound C5a in samples from patients undergoing cardiopulmonary bypass, which is known to be associated with complement activation. C3 activation products and the terminal complement complex were measured as well. RESULTS: Plasma levels of C3 activation products and the terminal complement complex increased rapidly and significantly after the onset of cardiopulmonary bypass until they reached a plateau after 30 minutes. The concentration of plasma C5a increased steadily to twice baseline at the end of bypass. The concentration of leukocyte-associated C5a increased threefold after 10 minutes of cardiopulmonary bypass, when a plateau was reached. A positive correlation was found between levels of plasma C3 activation products or terminal complement complex and plasma C5a plus cell-associated C5a but not between C3 activation products or terminal complement complex and either one of the C5a variables. CONCLUSIONS: We conclude that both plasma C5a and leukocyte-associated C5a are needed for monitoring in vivo C5a generation.

Cardiopulmonary Bypass↗

PubMed1997

Extracorporeal membrane oxygenation using a centrifugal pump and a servo regulator to prevent negative inlet pressure.

BACKGROUND: We studied whether negative inlet pressure created by a centrifugal pump during extracorporeal membrane oxygenation damages blood. METHODS: Fresh, whole human blood and primer were circulated through a test circuit, applying an inlet pressure of 0, -50, or -100 mm Hg. Thereafter, hemolysis and kidney function were compared between 6 patients treated before and 14 patients treated after inclusion in our setup of extracorporeal membrane oxygenation with a servo inlet pressure regulator. RESULTS: In vitro, negative inlet pressure caused substantial hemolysis, leukocyte and platelet destruction, and complement activation. Maximal plasma free hemoglobin concentrations were 199 mg/100 mL before use of the servo inlet pressure regulator and 40 mg/100 mL afterward (p = 0.06), and serum creatinine peaked at 330 and 115 mumol/L, respectively (p = 0.03). The minimal 24-hour diuresis normalized for weight was 4.8 mL/kg before use of the servo inlet pressure regulator and 45.6 mL/kg afterward (p = 0.03). Three of 5 evaluable patients before use of the servo inlet pressure regulator and 1 of 14 patients after inclusion in this setup experienced anuria (p = 0.04). CONCLUSIONS: There were strong indications that reduction of negative pump inlet pressure with the servo regulator prevented hemolysis and kidney damage.

Complement Activation↗

PubMed1997

Effect of whole and fractionated intravenous immunoglobulin on complement in vitro.

Intravenous immunoglobulins (IVIG) are increasingly used for treatment of inflammatory diseases, and the modulation of complement may contribute to some of its beneficial effects. IVIG may bind C1q and activated C3 and C4, and enhance inactivation of C3b. We have previously shown that IVIG inhibited complement-mediated lysis solely via its Fc part through interaction with the classical pathway. In the present study we have investigated whole IVIG (Octagam, and Sandoglobulin) and the monomer, dimer and multimer fractions of Octagam with respect to complement activation in serum and inhibition of complement lysis of red cells. The isolated fractions were found to be stable, homogeneous (monomer, dimer or multimer) and pure (virtually only IgG). Both whole IVIG and its fractions significantly activated complement in serum and inhibited hemolysis compared with human albumin. These effects were most pronounced in the monomer, less in the multimer and least in the dimer fraction. The complement activation was shown to be mediated through the classical pathway since formation of C1rs-C1inh complexes and C4bc were increased, in contrast to Bb. Surprisingly, heat aggregation of Octagam was not followed by a corresponding increase in complement activation, as would be expected, unless it was dialysed before heating, suggesting that it is stabilized to avoid excess activation. In conclusion, the results support the hypothesis that IVIG causes a mild activation of complement in vitro. We suggest that this effect may contribute to the complement inhibitory properties of IVIG by diverting complement deposition from the target to the fluid phase.

Animals↗

PubMed1997

Duraflo II coating of cardiopulmonary bypass circuits reduces complement activation, but does not affect the release of granulocyte enzymes : a European multicentre study.

OBJECTIVE: This study was carried out to: (a) compare complement and granulocyte activation during cardiac operations in patients operated with cardiopulmonary bypass coated with heparin by the Duraflo II method, with activation in patients operated with uncoated circuits; and (b) relate complement, and granulocyte activation to selected adverse effects. METHODS: In a multicentre study among Rikshospitalet, Ullevaal Hospital in Norway and Uppsala University Hospital in Sweden, plasma concentrations of the complement activation products C4b/iC4b/C4c (C4bc), C3b/iC3b/C3c (C3bc), the terminal SC5b-9 complement complex (TCC), and the granulocyte proteins myeloperoxidase and lactoferrin were assessed in two groups of patients undergoing aortocoronary bypass. Seventy-six patients underwent surgery operated with circuits coated by the Duraflo II heparin coating and 75 uncoated circuits. The same amount of systemic heparin was administered to all patients. RESULTS: In both groups a significant increase in C4bc was first seen by the end of operation, from 86.7 +/- 12.5 to 273.0 +/- 277.4 nM in controls and from 86.9 +/- 18.5 to 320.2 +/- 190.5 nM in the control group, confirming previous documentation that the classical pathway is not activated during CPB, but as a consequence of protamin administration. The formation of C4bc did not differ significantly between the two groups. In the uncoated group the C3bc concentration increased from 124.0 +/- 15.3 to a maximum of 1176.1 +/- 64.7 nM (P < 0.01) and in the coated group it increased from 129.8 +/- 16.1 to a maximum of 1019.4 +/- 54.9 nM (P < 0.01) during CPB. Summary values but not peak values differed significantly between the groups. In the uncoated group the TCC concentration increased from 0.52 +/- 0.03 to a maximum value of 8.09 +/- 0.57 AU/ml (P < 0.01) while in the coated group the TCC concentration increased from a baseline of 0.53 +/- 0.03 to a peak value of 5.2 +/- 0.24 AU/ml (P <0.01). The difference between the peak values was statistically significant (P = 0.00002). In both groups a significant increase in myeloperoxidase and lactoferrin release was observed by the end of operation. There was no difference in myeloperoxidase or lactoferrin release between the two groups. TCC levels were compared to the occurrence of perioperative infarction, development of lung or renal failure, postoperative bleeding, time on ventilator and days in hospital. Three patients developed perioperative infarction; the peak levels of TCC were significantly higher in these patients than in the 148 patients that did not develop infarction. The reduction in TCC formation in the heparin-coated group was not associated with differences in any of the other clinical parameters. Few adverse effects occurred in the study. The peak values of C3bc were higher in the patients needing inotropic support that in those who did not, the relevance of this finding remains uncertain. CONCLUSION: It is concluded that the Duraflo II heparin coating reduces complement activation, particularly TCC formation, during CPB, but not the release of specific neutrophil granule enzymes. No certain correlation was established between complement and granulocyte activation and clinical outcome.

Aged↗

PubMed1997

A neoepitope-based enzyme immunoassay for quantification of C1-inhibitor in complex with C1r and C1s.

Monoclonal antibodies (MoAb) recognizing neoepitopes exposed on activation products of complement proteins but hidden in the native components have been used for quantification of activated complement. A previously produced and characterized mouse MoAb, recognizing a neoepitope on the human plasma protein C1-inhibitor complexed with its substrates, was used to design an enzyme immunoassay for detection of C1-inhibitor complexed with C1r and C1s. These complexes are indicators of early classical complement pathway activation. The standard was serum activated with heat aggregated IgG defined to contain 1000 arbitrary units (AU)/ml. The lower detection limit was approximately 0.05 AU/ml corresponding to 0.005% of fully activated serum. The reliability of the assay, including day-to-day variation, was tested. Intra-assay variation coefficients were 12% for low plasma control and 13% for high plasma control (n = 12 for both). Inter-assay variation coefficients were 12% for low control (n = 6), 19% for high control (n = 6) and 15% for the normal plasma control (n = 9). A 2.5-97.5 percentile reference range (normal blood donors) was 16-33 AU/ml. Two patients with systemic lupus erythematosus had considerably elevated plasma levels of the activation product (56 and 62 AU/ml), and six patients with hereditary angioedema had normal plasma levels despite considerably reduced C1-inhibitor concentration. We conclude that the present method is sensitive and reliable for detection of early classical pathway activation and superior to previously published methods by utilizing neoepitope specificity and non-radiolabelled reagents.

Animals↗

PubMed1997

Immobilized heparin inhibits the increase in leukocyte surface expression of adhesion molecules.

The effect of heparin coating of artificial materials on the surface expression of leukocyte surface molecules was assessed in blood from 9 donors in an experimental model of extracorporeal circulation. The leukocyte surface molecules CD11b, complement receptor type 3 (CR3), and CD45, leukocyte common antigen (LCA), on granulocytes and monocytes exposed to unmodified polyvinyl chloride tubes increased significantly compared with unmanipulated controls (p < 0.001) whereas a very modest and nonsignificant increase was observed in blood circulated in heparin-coated tubes. Accordingly, a highly significant reduction in expression of the 2 molecules was achieved by heparin coating (p < 0.001). The expression of CD11b and CD45 correlated with the degree of complement activation in plasma (rho = 0.6, p = 0.003). The expression of CD14 (endotoxin receptor) and CD16 (Fc gamma III receptor) was increased to the same extent in blood from unmodified and heparin-coated tubes (p < 0.02), and no correlation to complement activation was seen (rho = -0.275, p = 0.17 and rho = -0.004, p = 1, respectively). In conclusion, heparin coating of artificial surfaces has a substantial effect, reducing the expression of molecules involved in cellular adhesion and activation (CD11b and CD45), and the increase of these molecules by unmodified surfaces is complement dependent. In contrast, up-regulation of other surface molecules (CD14 and CD16) seems to be independent of heparin coating and complement activation and, thus, might be regulated by other mechanisms.

Anticoagulants↗

PubMed1997

Acquired C3 deficiency in patients with alcoholic cirrhosis predisposes to infection and increased mortality.

BACKGROUND: Acquired deficiencies of certain complement proteins and impaired opsonisation activity have been implicated in the pathogenesis of the increased susceptibility to infections of patients with alcoholic cirrhosis. METHODS: Serum concentrations of C3 and C4, plasma concentrations of C3bc, C9, and the terminal C5b-9 complement complex (TCC), and haemolytic complement activity (classic and alternative pathway) of serum, and serum opsonic activity were determined in 46 patients with compensated alcoholic cirrhosis, 31 who were decompensated, and in 15 healthy subjects. After 19 months (median) the investigated variables were analysed for their use in prognosis of recurrent infections and survival. RESULTS: C3 and C4 concentrations and the haemolytic complement activity of the alternative pathway were decreased in decompensated cirrhotic patients compared with controls (p < 0.01). Univariate analysis (log rank test) showed that low concentrations (< or = lower quartile) of C3 (p < 0.001) and C3bc (p < 0.05), haemolytic complement activity of the alternative pathway (p < 0.01) and classic pathway (p < 0.05), and decompensated cirrhosis (p < 0.001) were associated with an increased risk of infection and increased mortality. Multivariate (Cox) analysis showed that low C3 concentrations and decompensation of cirrhosis were significant predictors of infections and mortality (p < 0.02). CONCLUSIONS: Low serum C3 concentrations and decreased haemolytic complement function predisposes to infection and increased mortality in patients with alcoholic cirrhosis.

Adult↗

PubMed1997

Effects on complement, granulocytes and platelets of a leukocyte-depletion filter during in vitro extracorporeal circulation.

In an in vitro study, extracorporeal circuits equipped with either a leukocyte-depleting filter (n = 5) or a standard arterial-line filter (n = 5) were perfused for 120 minutes with fresh human whole blood. Leukocyte activation, leukocyte and platelet counts and complement activation were studied. Significant reduction of leukocyte and platelet counts and significant activation of leukocytes and of platelets were found in both groups, but without significant intergroup difference for any parameter after 120 minutes of perfusion. The leukocyte-depleting filters, however, were somewhat more effective in removing leukocytes during the initial 30 minutes of circulation.

Complement System Proteins↗

PubMed1997

Modest release of adipsin/factor D by liposuction when using the superwet or tumescent technique.

Human adipsin is recognized to be identical to factor D, which plays an important role in activation of the alternative complement pathway. Since adipsin/factor D is present in high amounts in adipose tissue, liposuction theoretically could result in an increased release of this serine protease into the bloodstream. In the present study, adipsin/factor D was measured in 22 patients undergoing syringe-assisted liposuction using the superwet or tumescent technique. Despite a relatively high mean aspirate volume (2648 ml), only a very modest increase in adipsin/factor D concentration was found during liposuction. All values before, during, and after liposuction were within the range found in healthy blood donors. Furthermore, there was no correlation between adipsin/factor D values and C3 activation products. We conclude that liposuction with the present techniques results in a very modest release of adipsin/factor D that is not associated with increased complement activation.

Complement Activation↗

PubMed1997

Biocompatibility: complement as mediator of tissue damage and as indicator of incompatibility.

The fully biocompatible surface is the host's own intact endothelium. Blood contact with a damaged or foreign endothelium, or with an artificial surface, will lead to a certain degree of activation of the defense systems. Complement is one of these systems which has a unique property to distinguish between 'self' and 'non-self'. Recent data using complement-specific inhibitors like soluble CR1 and monoclonal antibodies to C5 have shown that complement is not only associated with, but in fact contributes to, the whole body inflammatory reaction seen as a complication to cardiopulmonary bypass (artificial surfaces) and is responsible for the hyperacute rejection of xenografts (foreign endothelium). Complement activation, as measured by assays specific for neoepitopes exposed in the activation products, is a sensitive indicator of bioincompatibility. These assays have been increasingly important after a causal link between complement activation and tissue damage was demonstrated. Efforts have been made to improve the biocompatibility of artificial surfaces, including coating with heparin. This procedure not only improves coagulation compatibility, but also markedly reduces complement activation. Models to study complement compatibility in vitro and in vivo are described, and recommended complement activation assays reviewed.

Animals↗

PubMed1996

Clinical immunology.

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Allergy and Immunology↗

PubMed1996

[Reduced blood utilization in hip arthroplasty. Introduction of a blood preservation program].

In spring 1992 a blood conservation programme was established at Nordland Central Hospital with emphasis on indications for blood transfusion and intraoperative blood salvage (cell-saver). Medical records from all patients who underwent hip arthroplasty during the period 1 June 1991 to 28 February 1994 were examined. Mean transfusion of homologous SAGMAN-blood (bank blood) was substantially reduced during the period: for total prosthesis (n = 192) from 2.6 to 1.1 units per operation (p < 0.0001) and for hemiprosthesis (n = 66) from 3.1 to 0.9 units per operation (p = 0.0202). The percentage of patients in each of these two groups who did not receive blood transfusion at all increased from 18 to 61 in the first group (p < 0.0001) and from 24 to 65 (p = 0.0202) in the second. The substantial reduction of bank blood transfusion in this material conforms with current international transfusion guidelines. A particular benefit, considering the risk of transfusing contagious blood, is the marked increase in the number of patients who did not receive any blood product at all.

Aged↗

PubMed1996

Complement-fixing islet cell antibodies in type-1 diabetes can trigger the assembly of the terminal complement complex on human islet cells and are potentially cytotoxic.

Forty-one sera of patients with IDDM (insulin-dependent diabetes mellitus) containing complement-fixing islet cell antibodies were analyzed for their ability to activate TCC (terminal complement complex). Eighteen sera were found to promote deposition of TCC on human islets of pancreatic cryostat sections with a nonhomogeneous pattern of distribution corresponding to that of insulin. Activation of TCC by IDDM serum and binding of this complex to islet cells was confirmed using purified islets. Flow cytometric analysis of islet cell treated with a TCC+ IDDM serum showed IgG binding to the cell surface. The same serum had a cytotoxic effect on islet cells in the presence of human C. These results obtained with a homologous system of C activation by IDDM sera suggest that TCC may contribute, at least in part, to the pancreatic beta cell damage.

Autoantibodies↗

PubMed1996

Release of interleukin 6 and activation of complement during and after paediatric cardiopulmonary bypass. Effect of autotransfusion of shed mediastinal blood and ultrafiltration.

Interleukin-6 (IL-6) and the complement activation products C3bc and terminal complement complex (TCC) were measured in three groups of children undergoing open heart surgery. One group was treated with intraoperative extracorporeal ultrafiltration and postoperative autotransfusion of shed mediastinal blood, one group was subjected to autotransfusion only and in one group none of these procedures were performed. No differences between the groups were observed concerning the degree of complement activation. Peak and total accumulated level of IL-6 was significantly higher in the group subjected to ultrafiltration and autotransfusion compared to the group treated conventionally with no interventions. IL-6 may be a sensitive marker of maneuvres increasing the inflammatory load during and after open heart surgery in children.

Biomarkers↗

PubMed1996

Tubing loops as a model for cardiopulmonary bypass circuits: both the biomaterial and the blood-gas phase interfaces induce complement activation in an in vitro model.

We describe here a model for the study of blood/surface and blood/air interaction as encountered in cardiopulmonary bypass (CPB) circuits. Polyethylene tubing was filled with serum or blood and closed end to end into loops whereby the volume of the remaining air bubble was inversely varied with respect to that of the fluid. The loops were rotated vertically in a water bath at 37 degrees C. The profiles of C3a, iC3, and TCC generation were similar to those observed at surgery, involving CPB. Soluble heparin and heparan sulfate inhibited both C3a and TCC formation, but surface-conjugated heparin had only a minor effect. Binding of C3 and/or C3 fragments to the heparin surface was much reduced compared to the amine matrix to which heparin was linked, but compared with the polyethylene surface the effect was less pronounced. These data suggest that, in addition to the biomaterial surface, the blood-gas interface seems to play an important role in the activation of complement and that this activation is inhibitable by high concentrations of soluble glucose aminoglycans.

Biocompatible Materials↗

PubMed1996

Adhesion molecule expression and complement activation in vessel walls in synovial tissue from patients with chronic inflammatory joint disease.

Histopathology demonstrating a manifest vasculitis is a rare event in synovial tissue (ST) from patients with chronic inflammatory joint disease. As a possibly more subtle sign of a vasculitic process, complement activation in vessels in ST was studied. In the same tissues, the expression of the adhesion molecules ICAM-1 and E-selectin in vessel walls was examined, to see if the expression was related to vasculitic processes. The study was performed by use of direct immunofluorescence technique on cryostat sections of ST, using mouse monoclonal antibodies to the terminal complement complex (TCC, C5b-9), ICAM-1 and E-selectin. Expression of ICAM-1 was found in the vessel walls in all of 28 tissues tested, whereas E-selectin was found in 4 cases and TCC in 11. E-selectin and TCC were found together in only 1 tissue. The study supports the view that ICAM-1 is always, or nearly always, present in vessel walls in synovial tissue from patients with chronic inflammatory joint disease. E-selectin and TCC may also be present, but the lack of association between these two proteins suggests that the mechanism leading to a complement mediated vasculitic process is different from that causing expression of E-selectin.

Animals↗

PubMed1996

Centrifugal pump and heparin coating improves cardiopulmonary bypass biocompatibility.

BACKGROUND: Centrifugal pumps are being used increasingly for short-term extracorporeal circulation purposes such as during heart operations. Whether the centrifugal pump improves the cardiopulmonary bypass biocompatibility has not been fully documented. METHODS: A roller pump (n = 20) was compared in vivo with a centrifugal pump (n = 20) in groups of patients in which cardiopulmonary bypass circuits that were either totally heparin coated (Carmeda BioActive Surface; n = 20) or uncoated (n = 20) were used. We expected the heparin coating to attenuate blood activation, thus possibly making the comparison of the two pumps easier with respect to their different blood activation potentials. Samples of blood plasma, obtained during cardiopulmonary bypass from low-risk coronary artery bypass grafting patients, were analyzed for hemolysis (plasma haemoglobin), complement activation (C3bc and the terminal complement complex), a complement lytic inhibitor (vitronectin), coagulation activation (fibrinopeptide A), granulocyte activation (lactoferrin), and platelet activation (beta-thromboglobulin). RESULTS: The concentrations of terminal complement complex, lactoferrin, and beta-thromboglobulin were significantly lower in association with heparin-coated surfaces. The concentration of plasma hemoglobin was significantly lower in association with the centrifugal pump. In uncoated circuits, the beta-thromboglobulin level was significantly higher in association with the roller pump than with the centrifugal pump, but this significant reduction in the beta-thromboglobulin level did not hold true for the heparin-coated circuit group. CONCLUSIONS: A heparin-coated cardiopulmonary bypass surface reduces the blood activation potential during cardiopulmonary bypass, and the centrifugal pump causes less hemolysis than the roller pump.

Adult↗