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Biomedical subjects

E Van Loghem

Publications and source records attributed to E Van Loghem.

At least 19 recordsLinked to original sources
PubMed1988

Further contribution of common Gm*-Am* haplotypes and Km* alleles in the characterization of the Tunisian population.

The Gm, Am and Km allotypes have been investigated in 405 sera from unrelated students and blood donors coming from the different areas of Tunisia. Thirty Gm and fourty-seven Gm-A2m common phenotypes have been observed. Eleven Gm* and seventeen Gm*-A2m* common haplotypes have been deduced from these phenotypes. The Tunisian population appears as mainly Caucasoid (combined frequency of Caucasoid Gm*-Am* haplotypes in the order of 0.81-0.82) with a relatively important Black contribution in the gene pool (combined frequency of Negroid Gm*-Am* haplotypes of 0.17-0.18) and a very low Oriental participation (0.01-0.02). Our results are compared to those previously reported for two other samples of the Tunisian population, the first from the regions of Mahdia and Sfax and the second from several villages of Berbers, the first inhabitants of Tunisia. Likewise, other comparisons are made with populations from Africa, Europe and Asia, since Tunisians are a mixture of Berbers, invaders and immigrants from different origins.

Female↗
PubMed1988

Uncommon Gm* haplotypes in the Tunisian population: further contribution to the genetics of the IgG immunoglobulins.

In this work, eight family studies were conducted to establish the suspected unusual Gm* haplotypes in 13 persons (among 418) showing uncommon Gm phenotypes. Usually, the Gm (21 and 28)--or Gm (g1 and g5)--allotypes are both present or absent. Exceptions to this rule were observed: on the one hand, only the Gm (28) allotype was present in 12 persons, and on the other hand, only the Gm (21) allotype was found in 1 person. Such events could be explained, in some cases, by equal crossovers or point mutations, and, more generally and very likely, by gene conversions. Other interesting results are also presented, as, on the one hand, silent genes homozygous at the C gamma 4 locus and, on the other hand, a homozygous multigene deletion encompassing the C alpha 1, psi gamma, C gamma 2 and C gamma 4 loci.

Chromatography, Affinity↗
PubMed1984

Linkage studies in autosomal dominant facioscapulohumeral muscular dystrophy.

Linkage studies were undertaken in 120 individuals from 10 kindreds with autosomal dominant facioscapulohumeral muscular dystrophy using 35 different marker genes. No linkage was found. The highest lod score was 1.438 for the immunoglobulin heavy chain gene cluster (IGH) at a recombination fraction of 0.2. IGH is located on the long arm of chromosome 14. Based on scores of other marker genes and on a recombination map of chromosome 14, the probability that the gene for facioscapulohumeral muscular dystrophy is located on chromosome 14 is estimated to be approximately 6%.

Adolescent↗
PubMed1983

Simultaneous absence of the human IgG1, IgG2, IgG4 and IgA1 subclasses: immunological and immunogenetical considerations.

Simultaneous absence of the IgG1, IgG2, IgG4 and IgA1 immunoglobulins has been unambiguously demonstrated in a healthy 75-year-old woman by testing for allotypes, isoallotypes and for isotypes of these four subclasses. Only IgM, IgD, IgG3, IgA2 and IgE were present. The IgG3 levels were significantly increased. Family investigation showed inheritance of a haplotype Gm-;-;b A2m2. This person is homozygous for an extensive DNA deletion including the C gamma 1, C gamma 2, C gamma 4 and C alpha 1 genes.

Aged↗
PubMed1983

IgA1 half molecules in human multiple myeloma and the in vitro production of similar fragments from intact IgA1 molecules.

This paper describes an IgA related protein Vla which occurred in the serum and urine of a patient with multiple myeloma. The protein was isolated from urine; it had a molecular mass of 70,000 daltons. It was shown to be a two chain IgA half molecule, consisting of a deleted alpha heavy chain, with a molecular mass of 42,000 daltons, which was disulphide linked to a normal kappa type light chain. Fabc fragments were produced from an unrelated myeloma IgA. These had the same biochemical properties as protein V1a, except for the absence of the disulphide linkage between the deleted heavy chains and the light chains. Protein Vla and the Fabc fragments could both be cleaved by IgA1 protease from Streptococcus sanguis, which indicates the presence of the alpha 1 hinge region. An inventory of its antigenic determinants and their similarity to those of previously characterized F(abc)2 fragments, indicates that protein Vla, like the Fabc fragments, contains the CH1 and CH2 domains, but lacks most of the CH3 domain. The fact that cleavage by IgA1 protease from S. sanguis yields a Fab fragment but fails to yield a CH2 domain demonstrates that cleavage by the enzyme is not only restricted to the Pro227-Thr228 bond in the IgA1 hinge region.

Aged↗
PubMed1982

Staphylococcal protein A and human IgG subclasses and allotypes.

Staphylococcal protein A binds molecules belonging to the IgG1, IgG2, and IgG4 subclasses. IgG3 proteins generally do not bind, except for those coded by the two gamma 3 alleles, which are G3m(u-): G3m(b0,b3,b5,s,v). G3m(u) is located in the CH2 domain. The difference between G3m(u-) and G3m(u+) IgG3 proteins correlates with the sequence at position 339 in the CH2 domain--Ala and Thr respectively. There is another structural difference in the CH3 domain which correlates with protein A binding and non-binding: all IgG proteins that bind protein A have His at position 435, whereas those that do not, have Arg at that position.

Alleles↗
PubMed1981

Determination of IgG subclasses and Gm allotypes in culture supernatants of pokeweed mitogen-stimulated human blood lymphocytes.

Concentrations of the 4 IgG subclasses, of IgM, and of IgA were determined in culture supernatants of pokeweed mitogen-stimulated mononuclear cells isolated from human peripheral blood. Time-course studies showed cumulative secretion of IgM, IgA, and the subclasses IgG1, IgG2, and IgG3 but not of IgG4. In supernatants of 7-day cultures of unseparated mononuclear cells, IgG1 was predominant, followed by IgG2 and IgG3. Removal of most monocytes from the mononuclear cells resulted in an overall decrease of immunoglobulin production but had no influence on the relative IgG subclass distribution. In supernatants of T cell-enriched cultures, the synthesized IgG was deficient in IgG1. Likewise, in supernatants of B cell-enriched cultures, IgG2 exceeded IgG1 concentration. Elimination of the T gamma cells suggested some influence of this subset on IgG2 production. Gm allotypes determined in supernatants corresponded to those in serum of the blood donors.

Animals↗
PubMed1979

Additions to the myotonic dystrophy linkage group.

One hundred and thirty members of a family with 33 cases of Dystrophia myotonica (Dm) were tested for various genetic markers including Km, Jk, Lu and Se. All individuals tested were Lua negative, but many were heterozygous for the other markers. Except for two cases all patients with Dm were positive for Km3 and Jka and they were secretors. Assuming the genes are linked and that the order of the loci is Km, Jk, Lu, Se, Dm, then there were 22 meioses informative for Dm and in 10 of these a recombination must have occurred between two of the five loci. Looking at individual pairs of loci, there were no recombinations between Km and Jk in seven informative meioses, three recombinations out of 10 meioses informative for Jk/Se, no recombinations between Se and Dm in five informative meioses and three recombinations out of 12 meioses informative for Jk/Dm.

Female↗
PubMed1979

A search for association between IgD concentrations and immunoglobulin allotypes in 936 sera from a genetic isolate in Newfoundland.

Immunoglobulin allotype (Gm) data has been analysed agaonst immunoglobulin D (IgD) concentrations in a population study in Newfoundland. There was no significant difference between the distribution of IgD concentrations in people homozygous for the alleles G1m(f) and G3m(b) when compared with people homozygous for the alleles G1m(a) and G3m(g). These findings, involving 573 homozygous individuals as opposed to ninety-eight in an earlier study on a New York population, do not confirm the earlier findings. Thus a genetic influence on IgD concentration by Gm genes or genes closely linked to them is not universally demonstrable by typing for these four markers and by using the Mancini technique for mearusing IgD concentration.

Gene Frequency↗
PubMed1976

Kappa-chain deficiency. An immunoglobulin disorder.

Since kappa-chain deficiency is an unusual condition, we studied the clinical and laboratory findings in a patient with this deficiency. The patient had cystic fibrosis with concurrent malabsorption, diabetes mellitus and IgA deficiency. The serum levels of IgM and IgG were 0.85 and 7.22 mg per milliliter, respectively. Kappa type IgM and IgG was not present in serum and external secretions; gamma, mu and lambda chains were probably polyclonal in character. Antibodies against kappa chains were not detected in either the patient or the mother. Plasma cells containing kappa-type immunoglobulins were absent in jejunum samples and bone marrow; kappa-chainbearing B lymphocytes could not be detected in blood and bone marrow. The serum of one of the patient's sisters contained trace amounts of kappa-type immunoglobulins. The patient displays a complete absence of kappa-type immunoglobulins, probably owing to a genetic defect.

Antibodies, Anti-Idiotypic↗
PubMed1976

The first isoallotype of human IgA proteins. An antigenic determinant occurring as allotype in the IgA2 subclass and as isotype in the IgA1 subclass.

An antigenic determinant that occurs on all IgA proteins except on IgA2 proteins of the A2m2 allotype is described. The determinant is an isoallotype, being an isotype of IgA1 and at the same time an allotype of IgA2 proteins. It is proposed that the symbol nA2m2 be used for the new determinant, where n stands for isoallotype (formerly nonmarker) and A2m2 refers to the allotype to which it is antithetically related.

Epitopes↗
PubMed1976

The first example of an isoallotype of human IgG located on the Fd fragment.

An isoallotype of IgG is described that is an isotype on heavy chains of IgG3 and IgG4 proteins and an allotype for IgG1 proteins, in which it is associated with Glm(f). The isoallotypic determinant is located on Fd. Binding of light chains (independent of their type) is required for its antigenic expression, since isolated heavy chains are not reactive in inhibition tests. It is suggested that the coding for the amino acid sequence related to this isoallotype was present on the ancestral gene before the duplication of subclasses. The presence in many non-human primate species proves that it is strongly conserved in evolution.

Animals↗