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PubMed1984

Studies of complement autoactivatability in hereditary angioedema: direct relationship to functional C-1-INA and the effect of classical pathway activators.

It has been observed earlier that the hemolytic complement in diluted sera obtained from patients with hereditary angioedema (HAE) undergoes spontaneous decay when incubated at 37 degrees C. Employing individual serum from patients at different stages of this disease it was demonstrated that this spontaneous loss of hemolytic complement also occurs without dilution and is directly linked to the absence of functional C-1-INA. Incubation of HAE serum resulted in a loss of activity which appears to be dependent upon the concentration of functional C-1-INA. While C-1-INA levels less than 50 micrograms/ml lead to rapid depletion with time, reconstitution of deficient sera with highly purified C-1-INA or of undiluted NHS inhibited spontaneous activation. Furthermore, NHS was rendered susceptible to autoactivation when its C-1-INA was depleted by passage over an anti-C-1-INA Sepharose 4B affinity column in the presence of 10 mM EDTA, indicating that in the absence of functional C-1-INA, C1 undergoes an uninhibited spontaneous autoactivation which leads to the consumption of C4 and C2 but not C3. Consumption of C3 was observed, however, in HAE sera that contained a significant amount of immune complexes. Incubation of HAE sera with highly purified Hageman factor fragment (5 micrograms/ml), or aggregated IgG (2 mg/ml) was found to accelerate the rate of decay when compared to untreated samples while sera from patients under treatment with Danazol or Stanozolol failed to autoactive. These results suggest that, the absence of C-1-INA, may, by itself trigger the dissociation and autoactivation of C1 in the sera of such patients; however, the presence of other complement activators accelerates the reaction. This inherent property of HAE sera, i.e., spontaneous autoactivation at 37 degrees C, may be a useful screening test but direct determination of C-1-INA activity is required to establish the precise diagnosis.

Angioedema↗
PubMed1991

Neutrophil polarization and immunoelectrophoresis assays in the study of complement activation by biomaterials.

The neutrophil polarization assay, a technique used to measure chemotaxis, was adapted to examine complement activation. Complement activation in serum which had been incubated with metallic and polymeric biomaterials was examined using the neutrophil polarization assay and immunoelectrophoresis assay. In agreement with previous publications, nylon activated the complement cascade, but PTFE did not. The neutrophil polarization assay was found to be the most sensitive technique for examining complement activation by endotoxin but the immunoelectrophoresis assay is the technique most sensitive for detecting complement activation by cobalt powder. In both assays, complement activation was not detected in serum incubated with chromium powder. However, serum incubated with silver and nickel powder stimulated neutrophils to polarize indicating that these powders may activate complement.

Biocompatible Materials↗
PubMed1991

Normal human serum depleted of C1q, factor D and properdin: its use in studies of complement activation.

Normal human sera were depleted of C1q, factor D (D) and properdin (P) by a simple and reproducible procedure providing reagents for analysis of complement-dependent functions. Classical pathway activity was restored with purified C1q, and alternative pathway activity with purified D and P. Since both activation pathways were abolished, antibodies and other components could be removed without loss of complement activity during immunoabsorption procedures. Synergism between the two pathways during haemolysis of rabbit erythrocytes was clearly demonstrated, and was also found on analysis of C3 cleavage in serum incubated with other alternative pathway activators such as zymosan and inulin. Experiments with a Neisseria meningitidis serogroup W-135 strain isolated from a patient with inherited P deficiency showed that both pathways were capable of supporting antibody-dependent killing of the bacteria in serum. The alternative pathway was possibly more efficient than the classical pathway in the assay system. In C1q,D,P-depleted serum with high concentrations of anticapsular IgG antibodies, the addition of D alone resulted in efficient alternative pathway-mediated killing. The alternative pathway was equally efficient in a C1q,D,P-depleted serum with low concentrations of anticapsular antibody, but in this case the reaction required both D and P.

Animals↗
PubMed1984

Study of complement effects on kinetics of immune precipitation.

Influence of complement on the kinetics of immune precipitation was investigated by using simple kinetic tests. In the early phase of immune precipitate (IPPT) formation, it was demonstrated that complement caused inhibition of precipitation only. After formation of a certain critical IPPT mass, alternative pathway-dependent enhancement of precipitation was observed, followed by solubilization of 'enhanced' IPPT and, at last, by solubilization of preformed IPPT. Contrary to inhibition and IPPT solubilization, enhancement of IPPT formation does not change IPPT ability to react with fresh complement.

Animals↗
PubMed1987

Analysis of brome mosaic virus replication and aminoacylation functions by site-specific mutagenesis.

Brome Mosaic Virus (BMV) has a tripartite RNA genome; each RNA and the subgenomic RNA encoding the viral coat protein share a highly homologous region of about 200 nucleotides at the 3' end, for which a tRNA-like structure has been proposed. Several sequences encoding functions, including replicase binding, initiation of (-) strand synthesis and tyrosine esterification are known to be nested within this region. Elongation factor EF-1 alpha binds to aminoacylated viral RNAs, but not to the uncharged forms. An additional function of the tRNA-like structure is to serve as a substrate for nucleotidyl transferase, which adds the terminal adenosine residue to the (+) sense virion RNAs. A template-dependent and template-specific replicase preparation from BMV-infected barley leaves has been characterized and extensively used for replication studies in vitro that complement studies in vivo using protoplasts. The replicase has been shown to initiate de novo both (-) strand synthesis on supplied (+) strand RNAs, and (+) strand subgenomic RNA synthesis on supplied (-) sense RNA3 templates. RNA transcripts obtained by transcription in vitro of cDNA clones containing desired base substitutions and deletions, have been supplied as templates for replication, aminoacylation and other assays. Use of such mutant RNAs has allowed the promoters for both (-) strand synthesis and for synthesis of the subgenomic (+) strand RNA to be characterized and defined. The same approach has also been used to reveal regions of the tRNA-like structure involved in the tyrosylation of the BMV RNAs. These experiments showed that, although regions important in aminoacylation and replication functions overlap, they are not identical. Some of the mutations tested in vitro have also been tested for infectivity in vivo using both barley plants and protoplasts. Mutants retaining replicase and nucleotidyl transferase template activity, but having lost aminoacylation capability are of special interest in that they should reveal the role of aminoacylation in the infection process.

Base Sequence↗
PubMed1978

Fertility studies of complementing genotypes at the albino locus of the mouse.

Mice doubly heterozygous for two radiation-induced lethal alleles at the albino locus (C3H and C6H) show partial complementation: they are viable but runted and sterile. In C3H/C6H females oogenesis and mating are normal, but nearly all of their fetuses, even when genotypically normal (+/C3H or +/C6H), fail to survive beyond midgestation. Abnormalities of spermatogenesis, i.e. morphological defects in head condensation and a deficiency in numbers of maturing spermatids, are histologically detectable in the testes of C3H/C6H males. Spermatozoa from the vasa deferentia of such males are predominantly nonviable, immotile, and grossly abnormal in morphology.

Albinism↗
PubMed1976

[Genetic study of bacteriophage phi81. I. Isolation, study of complementation and preliminary mapping of amber-mutants of bacteriophage phi81].

123 Amber mutants of lambdoid bacteriophage phi81 are isolated and distributed into 19 complementation groups. Deletion mapping made possible to locate 5 gene groups on the genetic map of bacteriophage phi81 and to determine a region of possible location of mm' sticky ends on the prophage genetic map. A gene of phage phi81 is localized, which controls the adsorption specificity, and which functional similarity to a respective gene of phage phi80 is demonstrated.

Chromosome Mapping↗
PubMed1990

[A clinical study of complements as a marker of a hepatocellular carcinoma].

Serum complement C3, C4, and C3 proactivator (C3PA) have been evaluated for their diagnostic power in detecting a hepatocellular carcinoma (HCC) in patients with liver cirrhosis (LC). It was found that serum complement levels were lower in LC patients than in HCC patients and that difference of the serum C4 and C3PA levels between LC patients and HCC patients were statistically significant. In addition, serum C3 PA levels were found to correlate significantly with the serum gamma-GTP levels in HCC patients. Thus, using the cutoff values of C4 and C3PA as the mean values for HCC patients, examination of serum complement levels enabled the detection of 38% of the HCC patients with low AFP levels. These findings suggest that the examination of the serum complements may be a useful a tool for the detection of HCCs in LC patients.

Biomarkers, Tumor↗
PubMed1987

Tetanus toxoid-anti-tetanus toxoid complexes: a potential model to study the complement transport system for immune complex in humans.

Complement and its receptor on erythrocytes appears to play a physiological role in the elimination of large immune complexes (IC) in monkeys, and a similar system is likely to work in humans. Here we define a safe IC model which is suitable for clinical investigations. Soluble tetanus toxoid (TT)-human anti-TT (IgG) antibody complexes were prepared in large antibody excess. The size of the complexes was approximately 45 S. When incubated in normal human serum, 50% of the IC increased further in size, but remained soluble, and bound rapidly to human erythrocytes in vitro. This binding was shown to require intact classical pathway function. When injected into normal guinea-pigs a comparable proportion of IC bound immediately to blood cells (mainly to platelets). No platelet binding of IC occurred in C4-deficient guinea-pigs, but this binding was restored when C4 was supplied. Initial immune complex elimination was faster in C4 deficient than in C4-supplemented and normal guinea pigs. Thus classical pathway function appeared to be necessary for the normal processing, transport and elimination of TT-anti-TT complexes.

Animals↗