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Biomedical subjects

A Nicholson-Weller

Publications and source records attributed to A Nicholson-Weller.

63 records · Page 4Linked to original sources
PubMed1982

Combined hereditary deficiency of the sixth component of complement and factor VIII coagulant activity in a Dutch family.

Prompted by previous observations of defective blood clotting in rabbits deficient in the sixth component of complement (C6), and the discovery of a patient with both C6 and factor VIII deficiency, an evaluation was made of the haemostatic functions in this individual and his family members. The family contained three members homozygous for C6 deficiency (C6D); two of them were deficient also in factor VIII. In addition, one other member of the family was only deficient in factor VIII. The only C6D member without haemophilia A had a normal recalcification time without clinical symptoms of a bleeding disorder. Reconstitution of factor VIII and C6 deficient plasma from the various members of the family in this study with purified human C6 did not result in a change in the recalcification time. The results obtained from this study also indicate that there is no linkage between the inheritance of C6 and factor VIII.

Adult↗
PubMed1982

The presence of sialic acid on two related bacterial polysaccharides determines the site of the primary immune response and the effect of complement depletion on the response in mice.

We have examined the antibody responses in mice to two structurally similar antigens: the capsular polysaccharide of type 3 group B streptococci (sssGBS 3) and the capsular polysaccharide of type 14 pneumococci (sssPn 14), which differ only in the presence of a terminal sialic acid on the side chain of the former. The cells that produce antibody to the nonsialated antigen (sssPn 14) reside in the spleen, whereas the cells that produce antibody to the sialated antigen (sssGBS 3) do not. Cobra venom factor treatment of the mice before immunization abrogates the antibody response to the nonsialated antigen, but does not affect the response to the sialated antigen.

Animals↗
PubMed1981

Isolation of C4-binding protein from guinea pig plasma and demonstration of its function as a control protein of the classical complement pathway C3 convertase.

A decay-accelerating factor of the classical complement pathway C3 convertase, C4b,2a, has been purified to homogeneity from guinea pig plasma by a 5-step procedure that includes 5% polyethyleneglycol-4000 (PEG-4000) precipitation, Sepharose 6B gel filtration, heparin-Sepharose chromatography, DE-52 anion exchange chromatography, and Sepharose-C4gp affinity chromatography. The protein elicited a monospecific antiserum in a rabbit and was found with the Mancini technique in both normal and C4-deficient guinea pig plasma at a concentration of 60 microgram/ml. The purified protein gave a single stained band of 550,000 m.w. on SDS-PAGE under nonreducing conditions and a single band of 72,000 m.w. with reduction and alkylation. On the basis of its m.w. and subunit structure, ability to bind to a C4 affinity column, and ability to regulate the classical C system by accelerating the decay of the classical C3 convertase this protein represents the guinea pig analog of the human C4-binding protein.

Animals↗
PubMed1981

Purification from guinea pig erythrocyte stroma of a decay-accelerating factor for the classical c3 convertase, C4b,2a.

A protein with decay-accelerating activity for the classical C3 convertase, C4b2a, has been isolated on the basis of this function from guinea pig erythrocyte stroma. The isolation procedure for decay-accelerating factor of stroma (DAF-S) utilizes butanol extraction and chromatography on DEAE-Sephacel, hydroxylapatite, and phenyl Sepharose. Purified DAF-S has a m.w. of 60,000 and 65,000 on reduced and unreduced SDS gels, respectively, and exhibits m.w. of 30,000 and 175,000 on alkaline gradient gels, suggesting multiples of a 60,000-65,000 subunit. Purified DAF-S elicited a monospecific antiserum whose IgG fraction neutralized the decay-accelerating activity for C4b,2a affixed to 10(7) sheep erythrocytes (EAC1,4,2) in a dose-response fashion. The monospecific antiserum diluted up to 1:5120 agglutinated 1 x 10(6) guinea pig erythrocytes, but not sheep or human erythrocytes, suggesting that DAF-S, an integral membrane protein, has species-specific antigens that are expressed on the surface of the guinea pig erythrocyte.

Animals↗
PubMed1980

The role of specific antibody in alternative complement pathway-mediated opsonophagocytosis of type III, group B Streptococcus.

The native capsular polysaccharide antigen of type III, group B Streptococcus contains a terminal sialic acid residue on each repeating unit that masks all end-group galactopyranose residues and prevents alternative pathway complement activation by adult human sera in the absence of type-specific antibody. The critical role of the sialic acid residues in allowing the organism to evade activating the alternative complement pathway was shown when neuraminidase treatment of the organism converted the bacteria to activators of the alternative pathway as assessed in agammaglobulinemic serum. The requirement for specific antibody in permitting alternative pathway activation by the fully sialated bacteria was shown when sera that contained low levels of specific antibody failed to activate this pathway, and when prior absorption of serum that contained higher type-specific antibody levels with the capsular antigen failed to activate this pathway. The use of C2-deficient sera showed that the calssical pathway was not required for antibody-dependent alternative pathway activation. The use of isotonic, pH 7.5, veronal-NaCl buffer that contained 1% gelatin and that was supplemented to 4 mM Mg++ and 16 mM EGTA and adjusted to pH 7.5 (MgEGTA) ruled out the participation of the C1-bypass pathway. The presence of sialic acid on the bacterial surface is one means of evading an important mechanism of natural immunity, namely activation of complement by the alternative pathway. Only specific antibody, i.e., acquired immunity, can overcome this virulence factor.

Antibodies, Bacterial↗