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C Davrinche

Publications and source records attributed to C Davrinche.

35 records · Page 2Linked to original sources
PubMed1990

Prevalence of the 1.8 kb complement factor H mRNA in human lung.

Human complement factor H, described as a 155,000 molecular weight (MW) component, is a key factor in the control of the alternative pathway of complement activation. Using two human factor H cDNA clones, designated R2a (a clone derived from the 3' end of the factor H coding sequence) and B38-1 (a clone derived from the 5' end of the factor H coding sequence), as probes, three factor H-specific transcripts of 4.3 kb, 1.8 kb and 1.5 kb are usually detected in human liver, in equal abundance. Using these two factor H cDNAs to probe human lung RNA, there was evidence of a singular distribution of the factor H mRNA species in human lung compared to liver, in equal prevalence of the 1.8 kb factor H mRNA over the 4.3 kb factor H mRNA (a three- to fourfold difference). No significant expression of the 1.5 kb mRNA was detected. The prevalence of the 1.8 kb complement factor H mRNA leads to the speculation that the predominant factor H form biosynthesized in lung tissue is a truncated form of the factor H molecule.

Blotting, Northern↗
PubMed1989

Truncated forms of human complement factor H.

By the use of Western-blot analyses with polyclonal anti-(Factor H) antibodies, two low-Mr protein species of Mr 41,000 and 37,000 under non-reducing conditions and 43,000 and 40,000 under reducing conditions are consistently detected together with the well-known 155,000-Mr Factor H in human plasma and serum. These two additional species are also found in plasma, urine and synovial fluids. The 41,000-Mr species but not the 37,00-Mr species is detected by a monoclonal anti-(Factor H) antibody directed at the N-terminal part of Factor H. The 37,000-Mr species but not the 41,000-Mr species is detected by a monoclonal anti-(Factor H) antibody directed at the C-terminal part of Factor H. The 41,000-Mr and 37,000-Mr species are different from the well-characterized 36,000-Mr N-terminal tryptic fragment of Factor H. They are likely to represent translational products of the short Factor H mRNA species of 1.8 kb and 1.2-1.5 kb occurring in human liver that we have recently described.

Antibodies, Monoclonal↗
PubMed1989

Heterogeneous nature of human complement factor B: an electrophoretic approach for the analysis of its oligosaccharide chain structure and its physiological breakdown products.

Factor B is a glycoprotein which plays an essential role in the alternative pathway of complement activation. It carries the proteolytic activity of the convertases, and its physiological breakdown products Ba and Bb have some effects on the cells of the immune system. Human factor B exhibits a microheterogeneity and five isoforms are present in serum. The nature and origin of the microheterogeneity was investigated by using electrophoretic techniques. Treatments of factor B with neuraminidase and glycopeptidase F show that this microheterogeneity is mainly due to differences in its sialic acid content, varying from seven to eleven residues per molecule, and resulting in different oligosaccharide structures. However, deglycosylated factor B reveals a residual, nonallotypic variation in the Bb region of the polypeptide backbone. We confirm the presence of four asparagine-linked oligosaccharide chains of the complex type in native factor B, two of which are located in the Ba fragment, and the two others in the Bb fragment. The prevalent isoform of the native protein carries two sialic acid residues per oligosaccharide chain. Biosynthesis experiments show that the microheterogeneity of secreted factor B from HepG2 cells is acquired during the processing of its glycans. However, in vitro-secreted factor B is more heterogeneous than the serum protein. We propose a structural model for the microheterogeneity of the native protein and its physiological fragments. We discuss as well the feasibility of electrophoretic techniques to deal with microheterogeneity analysis.

Amidohydrolases↗
PubMed1988

Molecular basis for the microheterogeneity of human complement factor B.

The involvement of sialic acids in the microheterogeneity of human complement factor B was investigated. Desialylation kinetics revealed all the charge intermediates from a complex native to a homogeneous form. The relation between this heterogeneity and posttranslational events was explored in cultured hepatoma cells. Intracellular factor B exhibited the same isoelectric focusing pattern as the desialylated purified protein, whereas a highly heterogeneous form was secreted. In contrast, when N-glycosylation was prevented by tunicamycin, both intracellular and secreted forms focused like intracellular factor B from control cultures. These data lead to the conclusion that the microheterogeneity of human factor B results from different degrees of sialylation of its N-glycans.

Carcinoma, Hepatocellular↗
PubMed1986

Genetic variants of factor B in a population of Jordan.

BF phenotyping was performed in a population of Jordan. The observed allele frequencies were as follows: BF*S = 0.5457, BF*F = 0.3744, BF*SO7 = 0.0763, BF*F1 = 0.0075. These values are in agreement with the geographic position and the ethnic composition of Jordan.

Complement Factor B↗
PubMed1985

C3, BF and C4 polymorphisms in familial Mediterranean fever.

BF, C3 and C4 phenotyping were investigated in 34 patients with familial Mediterranean fever (FMF) and in 48 control subjects. Both groups included Sephardic Jews born in Tunisia, Algeria and Morocco. No linkage between BF, C3 and C4 polymorphisms and FMF was found.

Alleles↗
PubMed1984

Inulin-induced activation of factor B in whole serum: description of structural modifications in the Ba fragment.

The investigation of inulin-induced conversion of human factor B in serum by isoelectrofocusing revealed physiological modifications in the primary structure of the Ba fragment. Evidence has been obtained that a nascent Ba, generated by the hydrolytic action of the D component on B in serum, was a short-lived product and that a fast release of carboxy-terminal arginine and lysine residues occurred involving a serum carboxypeptidase B enzyme.

3-Mercaptopropionic Acid↗
PubMed1984

Genetic variants of human B component (BF system) and alpha-1-antitrypsin (PI system) in a population from Sardinia.

BF- and PI-type determinations have been performed in a population from Sardinia. The corresponding allele frequencies are as follows: BF*S = 0.5783, BF*F = 0.2189, BF*SO7 = 0.0046, BF*F1 = 0.1982 and PI*M1 = 0.5872, PI*M2 = 0.2041, PI*M3 = 0.0459, PI*M4 = 0.0940, PI*S = 0.0619, PI*Z = 0.0046, PI*N = 0.0023. Whereas the BF system shows the originality of the Sardinian population with a very high BF*F1 allele frequency, the PI system does not reveal any characteristic features.

Alleles↗
PubMed1983

HLA A*, B*-BF* and C4 A*, B* allele associations, with special reference to BF*S07, in the Tunisian population.

The HLA A*2, Bw*50-BF*S07-C4 A*2, B*1 linkage group was transmitted unambiguously in four unrelated Tunisian families. In one of these, another allele association, also carrying BF*S07, HLA A*9, Bw*50-BF*S07-C4 A*1, B*1, was encountered. The previously reported linkage disequilibrium between BF*S07 and HLA Bw*50, a subtypic specificity of HLA Bw*21, is confirmed in our study. The C4 A*2, B*1 haplotype, rare in the other populations until now studied, seems more frequent in Tunisia since it has been also found linked to HLA A*11, B*27 and BF*S in one of these families. Other allele associations were unambiguously demonstrated with predominantly the C4 A*3, B*1 haplotype, particularly a rare HLA A*3, B*18-BF*F1-C4 A*3, B*1 linkage group. A silent gene at the C4 A locus was found linked to HLA B*8.

Alleles↗
PubMed1982

Polymorphism of the third component of human complement.

Genetic polymorphism of the third component of human complement (C3) has been considered as a powerful marker for population genetics. Some studies on the distribution of gene frequencies have been performed among numerous populations all over the world. This review takes stock of population genetic studies reported up to now and points out some remarks on the distribution of the observed allelic frequencies.

Complement C3↗
PubMed1981

Allotypic variants of human C3 and properdin factor B in two French populations Normans and Basques.

Human Properdin factor B and C3 polymorphisms are of a real usefulness as genetic markers for population studies. In addition, they are more and more used for the determination of paternity cases. The present communication will be about Bf and C3 allele frequencies in two locally populations of France, Normandy and Western Pyrenees (Basques), The corresponding allele frequencies are as follows, for Normans : Bf(S) = 0.7422, Bf(F) = 0.2285, Bf(F1) = 0.0205, Bf(SO.7) = 0.0088; CsS = 0.788, C3F = 0.204, C3Srare = 0.004, C3Frare =0.004; and for Basques : BfS = 0.5625, BfF = 0.305, BfF1 = 0.1235, BfSO.7 = 0.0075; C3S = 0.7075 and C3F - 0.2925. French Basques are characterized by unusual allele frequencies in European Caucasoid populations for Bf as for C3 genes. A very high incidence of BfF1 allele is reported (BfF1 = 0.125), as previously observed [7, 17].

Alleles↗
PubMed1980

An improved three-step method for the purification of the third component of human complement.

This paper describes a three-step purification method for the third component of human complement (C3) from plasma. The method consists of PEG precipitation, DEAE-cellulose chromatography and preparative isofocusing in a granulated dextran gel, with pH range 5--8. From this last step, a highly purified form of native C3 was obtained as indicated by immunoelectrophoresis and polyacrylamide gel electrophoresis analysis. The average final recovery was 20%.

Binding Sites↗
PubMedDate not supplied

Differential modulation of complement factor H and C3 expression by TNF-alpha in the rat. In vitro and in vivo studies.

The biosynthesis of alternative regulatory complement protein factor H was investigated using both an in vivo rat model and an in vitro rat hepatocyte culture system, and compared to that of C3 component. Subcutaneous injection of a single dose of 20 micrograms of recombinant murine tumor necrosis factor-alpha (rmTNF-alpha) had no effect on factor H liver mRNA levels, while it increased C3 mRNA levels. In correlation with this, serum factor H levels remained unchanged after rmTNF-alpha injection, whereas C3 levels were increased. In contrast in vitro studies showed that rmTNF-alpha had no effect on factor H and C3 expression by rat hepatocytes. Recombinant human interleukin-1 alpha (rhIL-1 alpha) did not alter the expression of factor H, whereas it increased C3 expression, and recombinant human interleukin-6 (rhIL-6) stimulated expression of both proteins. This study shows that TNF-alpha is not directly responsible for the increased levels of factor H observed in vivo during induced inflammation in the rat. Its in vivo effect on C3 secretion might be secondary to the TNF-alpha-induced release of IL-1 and/or IL-6.

Animals↗