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Biomedical subjects

C Rivat

Publications and source records attributed to C Rivat.

At least 73 records · Page 4Linked to original sources
PubMed1977

IgG4 subclass in malignant melanoma.

Three hundred and ninety-seven sera from 185 melanoma patients were studied. These sera were classified into three groups according to stage of disease. An alteration in the level of the IgG4 subclass was found. It was related to the dissemination of disease. The percentage of abnormalities (either increased or decreased levels of IgG4) was more frequent in patients with stage II and III diseases (55 and 53%, respectively) than in patients with stage I(19%). The higher frequencies of high titers of IgG4 were essentially detected in advanced disease. The biologic significance of the increase of IgG4 in melanoma remains obscure. The increase may be related to the development of facilitating antibodies of the IgG4 subclass.

Female↗
PubMed1977

A human immunoglobulin in myeloma protein with anti-gastric parietal cell autoantigen activity.

A previously characterised IgA Kappa myeloma protein was isolated and purified. The (Fab) alpha fragments of this immunoglobulin were obtained. The IgA and Fab fragments reacted in vitro with gastric parietal cells (GPC) using animal gastric sections and with smooth cytoplasmic membranes obtained from rabbit fundus (gastric) mucosa. This was seen macroscopically and by light and electron microscopy. Evidence is thus provided which supports the concept that this homogeneous immunoglobulin is a typical monoclonal autoantibody.

Autoantibodies↗
PubMed1976

Deletion of hinge region of human myeloma IgG1 molecule (protein LEC) associated with nonexpression of G1m (3) and Km (1, 2) allotypes. A possible genetic explanation at the DNA level.

In this paper we report the structural basis for the nonexpression of G1m(3) and Km (1,2) allotypes in an IgG1 (kappa) human myeloma protein (protein LEC). Heavy and light chains spontaneously dissociate in sodium dodecyl sulfate polyacrylamide gels. Light chains appear to be covalently S-S bonded. Analysis of cysteine-containing peptides shows that the heavy chain of the IgG protein LEC has a deletion of residues 216-230, thus encompassing the entire hinge region. An arginine residue, characteristic of the G1m(3) marker is present at position 214. An alanine at position 153 and a leucine at position 191 of the light chain, characteristic of the Km (1, 2) allotypes, are present. It is likely that the double Km and Gm lack of expression is the result of the deletion. The genetic implications of the sequence of this protein are discussed.

Amino Acid Sequence↗
PubMed1976

Antigenic determinants of heavy chain variable regions: immumological typing of the human immunoglobulin VHIII subgroup.

An antigenic determinant of the VHIII variable region subgroup was defined by means of a heterologous specific antiserum using a hemagglutination inhibition procedure. The specificity of this antiserum was established in inhibition experiments with proteins either of known primary structure or belonging to a definite VH subgroup. A series of IgG, IgA, IgM and IgD monoclonal proteins was examined for the presence of this VHIII subgroup antigenic determinant. The data showed that 50% of the IgG, 62% of the IgA, 55% of the IgM and 41% of the IgD were VHIII-positive, and that certain "blocked" monoclonal immunoglobulins belonged to this subgroup. A preferential association of the VHIII antigenic determinant with the IgG1 and IgG3 subclasses was observed among IgG myeloma proteins while the preferential association was only observed with the IgG1 subclass when anti-Rh antibodies were studied. The VHIII subgroup exhibited nonallelic behavior.

Epitopes↗
PubMed1976

Evidence for "deleted" or "silent" genes homozygous at the locus coding for the constant region of the gamma3 chain.

Three uncommon stable Gm haplotypes, Gm3;23;--, Gm1,2,17;..;-- and Gm1,17;..;-- have been transmitted through 3 generations of two related Lebanese and Syrian families. No pathological consequence was noted in seven individuals, aged 14--65, whose sera were deficient for all the allotypes carried by the IgG3 chains. Among the different genetic events which could have produced these haplotypes (alteration of a regulatory gene, point mutation, gene hybridization, gene deletion), it appears that a structural deletion is the most probable explanation. The observed data can be explained by either a partial or a total deletion of the constant portion of the IgG3 heavy chain.

Adolescent↗
PubMed1975

An abnormal Cgamma 4 gene among the negro population.

An analysis of the IgG4-CH3 antigenic determinants by means of specific antisera using a hemagglutination-inhibition procedure among different populations has been done. Thus 3.67% of sera from Negroids have been found completely deficient in normal IgG4 subclass. Sera without normal IgG4 contained the other IgG subclasses. Family studies shown the transmission of an abnormal Cgamma 4 gene. Hypothesis of gene deletion, point mutation or gene hybridization were postulated. This last hypothesis seems the most valuable.

Africa↗
PubMed1975

[Kinetic study of human immunoglobulin G fragmentation by pepsin].

The rate of pepsin hydrolysis of the four subclasses of human IgG has been studied. The levels of undegraded IgG and of pep-F'c fragments have been determined by radial immunodiffusion using specific antisera against Cgamma2 and Cgamma3 domain antigenic determinants. This study shows that the four IgG subclasses have different susceptibilities to pepsin hydrolysis and defines the optimum conditions (times of hydrolysis) for the preparation of maximum yields of F (ab)'2 fragments and/or pep-F'c fragments.

Humans↗