PubMed Health⌕ Search

Biomedical subjects

P Garred

Publications and source records attributed to P Garred.

At least 19 recordsLinked to original sources
PubMed1992

Time for new concepts about measurement of complement activation by cardiopulmonary bypass?

Fifty-one patients admitted for routine coronary bypass operations were randomized to cardiopulmonary bypass with a membrane oxygenator (Capiox) or a bubbler (Polystan or William Harvey). Complement activation was measured using enzyme immunoassays for concentrations of C3 activation products and the terminal complement complex. From 5.8 to 8.1 arbitrary units (AU)/mL (medians), the plasma concentrations of C3 activation products increased by 119.9 AU/mL (Capiox), 124.6 AU/mL (Polystan), and 79.5 AU/mL (William Harvey) to a peak at closure of the sternum (not significant when related to baseline concentrations). The increase in C3 activation products and baseline C3 activation were linearly correlated (R2 = 0.30; p less than 0.0001). From 5.5 to 6.1 AU/mL, the plasma terminal complement complex concentrations increased by 45.2 AU/mL (Capiox), 15.4 AU/mL (Polystan), and 17.4 AU/mL (William Harvey) to a peak before termination of cardiopulmonary bypass. Maximal terminal (C5-C9) activation was significantly higher in the membrane oxygenator group (p less than 0.0001) and showed no relationship to C3 activation. Measurement of C3 activation only gives no information about C5-C9 activation. At present, terminal complement complex quantitation is probably the best index of C5-C9 activation during cardiopulmonary bypass.

Cardiopulmonary Bypass↗
PubMed1992

Gene frequency and partial protein characterization of an allelic variant of mannan binding protein associated with low serum concentrations.

Low plasma concentration of mannan binding protein (MBP) has been shown to be the basis for a common opsonic deficiency and suggested to be caused by a single nucleotide substitution at base 230 of exon 1 in the MBP gene. This substitution causes a replacement of glycine (codon GGC) with aspartic acid (codon GAC). Of 123 healthy Danish individuals investigated by polymerase chain reaction performed on exon 1, followed by restriction fragment length polymorphism or allospecific probing, 93 were homozygous (75.6%) for GGC, 28 heterozygous (22.8%), and two homozygous for GAC (1.6%). The gene frequency of the GAC allele was found to be 0.13. DNA sequencing of the cloned exon 1 from one GAC homozygous individual revealed no other substitution. The median MBP concentration in the group containing the GAC allele was 6.4 times lower than in the GGC homozygous group (195 and 1234 micrograms/l respectively). However, the range in plasma concentrations of MBP was wide and overlapping between the groups. MBP protein was detected in both the GAC homozygotes (9 and 387 micrograms/l). Furthermore, no difference in relative mass and biological activity (mannan binding) was found when sera containing the two forms of MBP were investigated. Accordingly, it can be concluded that the GAC allele is able to produce a functional MBP protein which may be detected in serum at low concentrations.

Adult↗
PubMed1992

Diallelic polymorphism may explain variations of the blood concentration of mannan-binding protein in Eskimos, but not in black Africans.

Mannan-binding protein (MBP) is a lectin which, upon binding to certain carbohydrates, activates the classical pathway of complement without the involvement of antibody or C1q. Deficiency of the MBP is associated with an opsonic defect and recurrent infections during early life. An amino acid substitution in the exon 1 at codon 54 in the MBP gene (GGC [glycine] to GAC [aspartic acid]) has been shown to be closely associated with low MBP concentration in Caucasoids. The gene frequency of the mutant allele in this population has been estimated at 0.13. In the study described here, we investigated the association between the mutant allele and MBP protein concentration in Eskimos from East-Greenland and black Africans from the Baringo District in Kenya. The frequency of the GAC allele was identical in Eskimos and Caucasoids (0.13). No overlap with regard to MBP concentration between the genotypes was found in the Eskimos. In contrast, the Africans revealed a low frequency of the GAC allele (0.009). However, the median MBP protein concentration was approximately 5 times lower among the Africans than the Eskimos. In 12.6% of the Africans and in 2.5% of the Eskimos, MBP was undetectable. Thus, MBP deficiency is the most frequent immunodeficiency so far described. The high prevalence of MBP deficiency among healthy individuals indicates that MBP deficiency also confers some selective advantages. We advance the hypothesis that MBP deficiency is maintained in populations because MBP deficiency decreases the infectivity of some intracellular micro-organisms which are dependent on opsonization.

Adolescent↗
PubMed1992

Surface epithelium related activation of complement differs in Crohn's disease and ulcerative colitis.

IgG1 and activated complement are colocalised on the colonic epithelial brush border in active ulcerative colitis. To investigate whether such deposition is specific for ulcerative colitis, we examined ethanol fixed mucosal specimens from 18 patients with Crohn's colitis and 14 with terminal ileitis by indirect two colour immunofluorescence staining. Monoclonal antibodies to the IgG subclasses and to neoepitopes of activated complement C3b and the terminal complement complex were used in combination with rabbit antiserum to C1q, C4c or cytokeratin. Granular deposition of C3b and terminal complement complex were observed at the luminal face of the surface epithelium in 10 of 18 patients with Crohn's colitis. Specimens from eight of 14 patients with ileal involvement were intensely stained for activated complement (primarily C3b) within the surface mucus layer. No epithelial IgG, C1q or C4c deposition was observed. The results suggest that early and late phase complement activation takes place at the luminal face of the epithelium in Crohn's disease. The absence of colocalised IgG and complement components involved in the classical activation pathway (C1q and C4c), however, suggest that other immunopathological mechanisms (the alternative pathway?) are primarily involved in Crohn's disease in contrast with ulcerative colitis.

Adolescent↗
PubMed1991

The use of flow cytometry to detect the biosynthesis of complement components.

Agarose beads, an activator of complement, were incubated with MRC-5 or He 9 fibroblast cell lines under serum-free conditions. The beads were tested for binding of anti-complement antibodies by flow cytometry with a FACS 440 using FITC-labelled anti-Ig detection antibodies. Controls consisted of co-cultured beads incubated with irrelevant antibody or albumin, beads maintained in cell cultures containing cycloheximide, and beads which were not exposed to cells. The histograms demonstrated positive staining with anti-C3c, -C5, -C7 and -C9, but not with anti-C6 and -C8. Flow cytometry with multiple histogram analysis confirmed that the differences between the positive curves and the controls were statistically significant. The results show that cell-derived complement components (C3, C5, C7 and C9) were deposited on the beads and could be detected by flow cytometry.

Cell Line↗
PubMed1991

[Cellular receptors and regulator proteins reacting with C3 activation products].

The central protein of the complement system is C3. The biological role of C3 includes development of inflammation, transport of immune complexes, phagocytosis and immunoregulation. These functions are mediated by the interaction between activated C3 and specific cellular C3 ligands. The article reviews aspects of the biological function of cell-bound C3 receptors and regulatory molecules, and the role of these molecules in autoimmune and inflammatory diseases.

Complement C3↗
PubMed1991

[The terminal complement complex (TCC)--a mediator in the development of disease in man?].

Activation of the terminal complement pathway leads to the formation of the terminal complement complexes (TCC). TCC exists in one active membrane form, C5b-9 and in one inactive fluid phase form, SC5b-9. The paper explores the structure and regulatory mechanisms of TCC. In addition, methods of detecting TCC in tissue and in biological fluids, guidelines for sampling and the importance of TCC as an inflammatory mediator in human disease are discussed.

Complement Activation↗
PubMed1991

[The role of complement system in infections].

The complement system plays an important role in host defence against infection, which includes localization and destruction of microorganisms. However, in the course of evolution pathogenic microorganisms have evolved mechanisms to escape complement attack. Furthermore, pathogenic microorganisms may mimic human complement proteins and use complement activation as a prerequisite for infectivity. This review focusses on the complex and often paradoxical role of the complement system in host defence against infection.

Antibodies, Bacterial↗
PubMed1991

Human IgG subclass pattern of inducing complement-mediated cytolysis depends on antigen concentration and to a lesser extent on epitope patchiness, antibody affinity and complement concentration.

The relative complement-mediated lytic capability of the IgG subclass isotypes was studied using a matched set of mouse-human chimeric anti-(4-hydroxy-3-nitrophenyl)acetyl (NP) antibodies. The subclass pattern was shown to be highly dependent on variations in antigen concentration and to lesser extent on variation in epitope patchiness, antibody binding affinity and complement concentration. In general, the IgG3 subclass was most effective in inducing cytolysis at the different conditions used and only at high antigen concentration did the IgG1 subclass mediated more efficient cytolysis than IgG3. The IgG2 isotype required a relative high antigen concentration to be cytolytic while the IgG4 isotype was not cytolytic at any of the conditions tested. These individual characters of each of the IgG subclasses makes it conceivable that a subtle system of immunoregulation exists among the subclasses.

Antibody Affinity↗
PubMed1991

Activation of complement, kallikrein-kinin, fibrinolysis and coagulation systems by urinary catheters. Effect of time and temperature in biocompatibility studies.

Urethral strictures induced by the use of latex catheters and combined silicone/latex catheters following open-heart surgery have been reported. These strictures differ from the post-catheterisation type in affecting a greater length of urethra. Recently it was shown that complement was activated by catheters which cause inflammation, in contrast to clinically silent catheters. The present study was designed to investigate a possible association between catheter-induced inflammation and activation of another mediator of inflammation, the contact system. We also investigated various in vitro conditions to optimise biocompatibility studies. Our data indicate that both the complement and the kallikrein-kinin system are activated by potentially harmful silicone/latex catheters and may be involved in the pathophysiology of catheter-induced urethral strictures. In vitro biocompatibility tests may be performed at both 20 and 37 degrees C. Glass test tubes may be used for in vitro complement but not for kallikrein-kinin investigations.

Adult↗
PubMed1991

C3 activation products, C3 containing immune complexes, the terminal complement complex and native C9 in patients with rheumatoid arthritis.

Complement activation products, C9 and C3-containing circulating immune complexes (CIC), were evaluated in plasma and synovial fluid (SF) from patients with rheumatoid arthritis (RA) and osteoarthritis. C3 activation products and the fluid phase terminal complement complex were considerably elevated in SF from RA patients reaching levels five- to eighttimes that in plasma, consistant with a local activation of the whole cascade in the joints. The results emphazise the importance of detecting C3 activation by neoepitope expression instead of single fragment determinations. The concentration of native C9 was lower in synovial fluid compared with plasma, consistant with the excessive local complement activation. Increased CIC levels which correlated with the degree of complement activation were also found in the SF from the RA patients.

Adult↗
PubMed1991

Activation of complement during apheresis.

C3 activation products and the terminal complement complex (TCC) were examined in plasma during plasmapheresis of patients with Guillain-Barré Syndrome (GBS) (n = 4), Waldenström's syndrome (n = 4), and hypercholesterolaemia (n = 1), or during cytapheresis of platelet (n = 10) and granulocyte (n = 2) donors. Blood specimens were taken before, during and after the procedures. There was a significant activation of complement after apheresis in the GBS patients and one of the patients with Waldenström's syndrome, but not in the other patients. There were no significant differences in complement activation products before compared with after cytapheresis in the healthy donors. This demonstrates the biocompatibility with respect to complement activation of the materials used. The observed complement activation in some of the patients during plasma exchange is probably caused by activation products in the replacement plasma.

Complement Activation↗
PubMed1991

Complement activation and bioincompatibility. The terminal complement complex for evaluation and surface modification with heparin for improvement of biomaterials.

The degree of biocompatibility of biomaterials can be evaluated using various assay systems detecting activation of the blood cascade systems, leukocytes or platelets. Activation of complement is one mechanism associated with adverse effects observed when bioincompatible materials are used. We present data showing that the terminal complement complex, an indicator of terminal pathway activation, is suitable for evaluation of biocompatibility of biomaterials such as cardiopulmonary bypass devices. Furthermore, our results suggest that bioincompatibility is improved when artificial surfaces are modified with end point attached functionally active heparin.

Complement Activation↗
PubMed1991

Biocompatibility of extracorporeal circulation. In vitro comparison of heparin-coated and uncoated oxygenator circuits.

Oxygenator/tubing sets coated with endpoint-attached heparin were compared to uncoated sets in a dynamic model of extracorporeal circulation. Biocompatibility was assessed by evaluations of complement activation and platelet loss. The median concentration of C3 activation products increased gradually from 12 AU/ml at baseline to 65 AU/ml after 120 minutes in the uncoated sets and from 12 AU/ml to 19 AU/ml after 120 minutes in the coated sets (p less than 0.002). The median concentration of the terminal complement complex in the uncoated sets increased gradually from 3.1 AU/ml at baseline to 18.2 AU/ml after 120 minutes. In the coated sets the terminal complement complex reached a peak of 12.0 AU/ml at 15 minutes and returned to baseline values at 60 minutes. Median platelet loss at 120 minutes was 166 x 10(9) in the uncoated and 21 x 10(9) in the coated sets (p less than 0.01). Heparin coating thus improved biocompatibility by reducing both complement activation and platelet loss.

Biocompatible Materials↗
PubMed1990

C3, C4, and the terminal complement complex differ from C1q by binding predominantly to the antigenic part of solid phase immune complexes.

The binding of the C components C1q, C4, C3, the terminal C5b-9 complement complex (TCC) and S protein to immune complexes was studied. The hapten 5-iodo-4-hydroxy-3-nitrophenacetyl (NIP) conjugated to BSA was adsorbed to polystyrene plates and reacted with a human IgG3-mouse chimeric anti-NIP antibody. After addition of serum a dose-dependent binding of C1q, C4, C3, and TCC to the immune complexes was found. An increase in the amount of NIP-BSA was associated with an increase in the binding of TCC and a decrease in the binding of S-protein. After addition of soluble NIP only 4 to 6% of the anti-NIP antibody remained bound to the Ag. C1q showed diminished binding after addition of NIP, whereas C4, C3, and TCC quantitatively remained bound to the Ag. Binding of TCC to the immune complexes was also found in an alternative assay, in which the anti-NIP antibody was adsorbed to the solid phase before NIP-BSA and an additional layer of anti-NIP antibody were added. The supernatants from the solid phase assay were tested for C3 activation and formation of the fluid phase TCC (SC5b-9). Activation of the C3 was reflected in the fluid phase by a dose-dependent increase in C3 activation products. This was not seen for TCC despite increased binding to the solid phase.

Animals↗
PubMed1990

Complement activation with bubble and membrane oxygenators in aortocoronary bypass grafting.

Thirty-three patients admitted for coronary bypass grafting were randomized to cardiopulmonary bypass with a bubble oxygenator (Cobe or Polystan) or a membrane oxygenator (SciMed). Plasma concentrations of C3 activation products and the terminal complement complex were measured using enzyme immunoassays. Both variables increased almost linearly after onset of cardiopulmonary bypass, with maximal concentrations at closure of the sternum. From a baseline of 7.5 to 12.0 arbitrary units (AU)/mL (medians), the concentrations of C3 activation products increased by 117.5 AU/mL (Cobe), 120.5 AU/mL (Polystan), and 213.3 AU/mL (SciMed). The increase in the membrane group was significantly higher than in the two bubble oxygenator groups (p less than 0.01). From a baseline of 0.9 to 1.3 AU/mL, the concentrations of terminal complement complex increased by 5.4 AU/mL (Cobe), 6.6 AU/mL (Polystan), and 7.7 AU/mL (SciMed) (differences not significant). The higher C3 activation caused by the membrane oxygenator may be explained by differences in flow profile and surface area in contact with blood. The study cannot confirm the general assumption that membrane oxygenators lead to lower complement activation than do bubble oxygenators.

Aged↗
PubMed1990

Epithelial deposition of immunoglobulin G1 and activated complement (C3b and terminal complement complex) in ulcerative colitis.

The epithelial destruction seen in ulcerative colitis remains unexplained. Complement activation has been proposed to be involved, but no definite evidence has been available to this end. In the present study, we examined immunohistochemically ulcerative colitis lesions with monoclonal antibodies to activation neoepitopes in the complement component C3b and in the cytolytically active terminal complement complex. Colonic tissue specimens from 23 patients with ulcerative colitis were examined by indirect two-color immunofluorescence staining with monoclonal antibodies to the four human immunoglobulin G subclasses and to activated complement C3b or terminal complement complex. All except two patients had activated C3b deposited apically on the surface epithelium of involved mucosa. Immunoglobulin G1 was found on the epithelium in extensively prewashed specimens from 7 of 11 patients, and a striking colocalization of immunoglobulin G1, C3b, and terminal complement complex was observed in 4. Immune deposits were not observed in 31 noninflamed specimens from the same ulcerative colitis patients. Only 1 of 44 histologically normal mucosae from 17 controls and 1 of 10 colonic adenomas contained some epithelial complement deposits. It is concluded that activated complement is often deposited along the brush border of the surface epithelium in active ulcerative colitis lesions and may be associated with immunoglobulin G1 autoantibody.

Adolescent↗