Biomedical subjects

M Brenden

Publications and source records attributed to M Brenden.

5 recordsLinked to original sources

PubMed1992

Apparently non-expressed alleles of factor B (BF) code for hypomorphic proteins.

In three families with an apparent non-expressed factor B (BF) allele (BF*Q0), advanced methods of isoelectric focusing for the determination of BF F subtypes revealed different hypomorphic BF products (BF QL) with functional hemolytic activity expressed by the assumed BF*Q0 allele. A Taq I and a Msp I restriction fragment length polymorphism as well as the Ba fragment of the expression products showed banding patterns for the BF*QL alleles corresponding to BF S types, whereas an altered Bb fragment was seen in two BF QL products. In one family an intragenic recombination site within the Bb part of the BF gene was assumed. Investigations of factor B and its conversion fragments, as demonstrated by the used methods, allow to complement molecular genetic investigations of BF*Q0 alleles in heterozygous genotypes on a protein level. We conclude that apparently non-expressed alleles of factor B code for hypomorphic but functionally active proteins.

Alleles↗

PubMed1991

Association of major histocompatibility complex class III complement components C2, BF, and C4 with Brazilian paracoccidioidomycosis.

A genetic influence of the major histocompatibility complex (MHC) on the susceptibility and the development of the different clinical forms of paracoccidioidomycosis (PCM) has been postulated. In the present investigation allotypes of MHC-coded class III gene products (complement components C2, BF, C4A, and B) were determined in 69 Brazilian PCM patients and 225 healthy control individuals matched for ethnic and geographic origin. The frequency of the non-expressed C4B allele (C4B*Q0) was significantly elevated in comparison to the controls (p less than 0.01; Fisher's exact test). Three out of 69 patients had a complete C4B deficiency as against 2 among 223 control individuals. The C4A*Q0 allele was also more frequent in the patients. Other C4 alleles were not seen to differ between the two groups. The analysis of BF allotypes showed a non-significant predominance of the rarer allele BF*S07 in the patients, whereas no difference in the distribution of C2 alleles was seen. The data on MHC class III association may support the hypothesis of immune response modulation in PCM and suggest a functional genetic role of complement action against the fungus and in the outcome of PCM infection. We conclude that MHC class III products, especially C4B*Q0, are associated with chronic uni- or multifocal PCM and may influence the course of the infection.

Adolescent↗

PubMed1990

Factor B reference typing report.

In a factor B (BF) Reference Typing of the VIth Complement Genetics Workshop and Conference, Mainz, FRG, 1989, 99 samples from 13 laboratories, including 18 families, were investigated with the majority of presently known typing procedures. Among the major ('standard') allotypes BF SO4 was found to be new. For the group of common BF F subtypes samples from 11 laboratories including complete family data from 5 laboratories were compared. The subtypes BF FA and FB were recognized and confirmed to be identical in the samples from all groups. Within a third group rare subtype variants of F and S were compared and characterized. In samples submitted from individuals with assumed non-expressed (BF*QO) alleles unexpected and hypomorphic gene products were seen. The investigation of DNA samples for restriction fragment length polymorphisms from the same set of individuals revealed a correlation of the Msp I 0.7-kb fragment with BF F, and confirmed the correlation of a Taq I 6.6-kb fragment with BF FA.

Alleles↗

PubMed1990

C4 reference typing report.

Human C4 is most polymorphic at the protein level, distinction between allotypes of the C4A and C4B proteins resting on electrophoretic migration patterns and difference in hemolytic activity. The aim of the C4 reference typing has been the definition of reference variants, the assignment of rare variants, and the investigation of duplicated, deleted, or non-expressed and hybrid genes. Samples from 136 individuals, predominantly with known segregation, from 16 laboratories were investigated by standard electrophoretic techniques, for their relative hemolytic activity, reactivity with monoclonal antibodies and Rg/Ch reagents, alpha-, and beta-chain types, relative electrophoretic migration distance, as well as the C4/21-OH-TaqI RFLPs. The results were evaluated in three groups; they consisted in the definition of the eight most common C4 alleles, and the ten Rg/Ch standard phenotypes in group I. In group II twelve C4A and fourteen C4B duplications among 96 complotypes, as well as eighteen deleted/non-expressed C4A and twenty-two C4B alleles, and hybrid alleles were seen by correlation of lytic activity, electrophoretic mobility, and monoclonal and/or Rg/Ch reactivity. Group III consisted of the newly defined allotypes A 8, A 7, A 58, A 55, A 45, B 45, B 35, and B 22, furthermore of alleles subdividing the A 1/A 91, and the B 13/B 12/B 11 regions. The reference typing has allowed reclassification of the majority of described C4 allotypes and resulted in a revision of the C4 nomenclature.

Blood Grouping and Crossmatching↗

PubMed1990

Relative electrophoretic migration distances for the classification of C4 allotypes.

For the definition of common C4 allotypes relative electrophoretic migration (RM) values were determined. A set of standard C4 variants were investigated by prolonged agarose gel electrophoresis and subsequent immunofixation with specific antiserum. RM distances were measured by laser densitometry. Using an arbitrary standard of 100 units for the migration distance between the C4B 1 and C4A 3 bands a total deviation of +/- 6.45% in more than 108 single determinations was found. The common C4 alleles used for standardization were C4A*6, C4A*4, C4A*3, C4A*2, C4B*5, C4B*3, C4B*2, C4B*1. In addition, side by side comparison and admixture of known variants will be necessary for the differentiation of some of the closely migrating allotypes. RM values are now available for eight alleles frequently found in all populations for future comparison and designation of newly discovered C4 allotypes.

Complement C4↗