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Biomedical subjects

C Rivat

Publications and source records attributed to C Rivat.

108 records · Page 6Linked to original sources
PubMedDate not supplied

Importance of the matrix and its chemical activation on the stability of immuno-adsorbents.

Various matrices were reacted with four different activation reagents, in order to prepare immuno-adsorbents for the selective removal of low-density lipoproteins from blood plasma of patients affected by hypercholesterolaemia. The resulting immuno-adsorbents were compared to that obtained earlier with cyanogen bromide activation, in terms of coupling yield, adsorption capacity and moreover stability towards the various chemical and biochemical conditions to which they are submitted during their handling. Tresyl chloride-activated Sepharose 6 Fast Flow turns out to afford optimal stability in the whole pH range tested.

Chromatography, Affinity↗
PubMedDate not supplied

[Two new peptic fragments of human IgA: F(abc)'2Alpha and [F(abc)'2]2alpha (author's transl)].

These experiments were undertaken to study the nature of the fragments produced by pepsin digestion of seric IgA. We describe a new fragment with a MW of 140,000 daltons. This fragment, the first produced during pepsin hydrolysis of monomeric IgA, corresponds to an IgA molecule which has lost its CH3 domain. We propose to call this fragment F(abc)'2alpha. It is gradually digested and transformed into an F(ab)'2alpha fragment. When polymeric IgA are digested, an extra fragment with a MW of 290,000 daltons is produced, which has kept its polymeric structure. It corresponds to a covalent [F(abc)'2]2alpha fragment. These findings suggest that there is an intersubunit disulfide bridge in the Calpha2 domain. These results also indicate that polymeric IgA proteins are more resistant to pepsin digestion than monomeric IgA proteins.

Humans↗
PubMedDate not supplied

A study of the breakdown of the third component of human complement (C3).

This paper reports the description of fragments of human C3, purified from aged sera. Sera were incubated at different temperatures (4 degrees, 20 degrees and 37 degrees C) for 8 days or more. At 4 degrees C, the major isolated fragment was C3b which showed a heterogeneity of structure. Under reducing conditions, it liberated a 40,000 dalton fragment which reacted against an anti-C3d and which we called "C3d-like". At 20 degrees C, C3b was partially destroyed to yield the C3c- and C3d-fragments. At 37 degrees C, C3d and C3c were obtained. C3c presented a structural heterogeneity. It was made either of two chains of 75,000 daltons or of three chains with 75,000, 38,000 and 31,000 dalton MW. The comparison of these fragments with those obtained by tryptic hydrolysis led us to propose a pathway to the degradation of C3 and to bring some informations about the structure of this molecule.

Complement C3↗
PubMedDate not supplied

Heavy and light chain variable region subgroups: antigenic analysis among human monoclonal immunoglobulins.

An antigenic analysis of human heavy and light chain variable region subgroups has been possible by means of heterologous specific antisera using a hemagglutination-inhibition procedure. The specificity of antisera had been shown to be directed against antigenic determinants of VkappaI, VkappaII, VkappaIII, VlambdaI, VlambdaII, VlambdaIII and VHIII by means of chemically subgrouped proteins. A series of IgG, IgA, IgM and IgD were examined for the presence of a VHIII variable region subgroup antigenic determinant. The data showed that 50% IgG, 62% IgA, 55% IgM, 45% IgD were positive for VHIII antigenic determinant. NH2 terminus blocked monoclonal immunoglobulin belonging to the VHIII subgroup were found, increasing incidence of this subgroup among IgG. A preferential association of VHIII antigenic determinant with IgG1, IgG3 subclasses was observed among IgG myeloma proteins while the preferential association was only observed with IgG1 subclass when anti-Rh antibodies were considered. Among 53 IgG of kappa type 20 (37%) kappaI, 30 (56%) kappaII, 3 (5%) kappaIII subgroups were found and among 42 IgG of lambda type 13 (31%) lambdaI, 13 (31%) lambdaII and 16 (38%) lambdaIII were observed. Although numbers are limited in each group for conclusions a study of VHIII and non VHIII antigenic subgroup determinant with respect to the light chain subgroups is given. The non-allelic behaviour of this VHIII antigenic determinant was observed. Preliminary data on the presence of these human antigenic determinants among different animals species were given.

Animals↗
PubMedDate not supplied

[Antigenic determinants of human immunoglobulin light and heavy chain variable regions. Comparison with animal species].

An antigenic analysis of human heavy and light chain variable region subgroups has been done on different animal species, by means of heterologous specific antisera using a hemagglutination-inhibition procedure. Excepted in lemur sera, where Vkappa III and Vlambda III are the only variable antigenic determinants found, all VL antigenic determinants tested were shown to be present in primates. In other mammals (carnivores, some rodents, some artiodactyls) several VL antigenic subgroup determinant were detected while others were not. No VL antigenic determinant was found in other classes studied. The VH III subgroup antigenic determinant was found among all primates, some mammals and avains. The results suggest that there has been more preservation in the variable region of immunoglobulin chains, and particularly VH III chain, than in the constant region of immuoglobulin molecule.

Animals↗
PubMedDate not supplied

Selective deficiencies in complement component : a family with hereditary C2 deficiency.

We report herein a new case of C2 deficiency in a patient with systemic lupus. The subject and one of her brothers, who shows no clinical manifestations, are hymozygous C2 deficient. All other family members are heterozygous for the C2 deficiency. Gene for C2 deficiency (C2d) was shown to be inherited with HLA-A9, B7/Bfs and HLA-A10, B27/Bfs haplotypes. This association has not previously been described.

Adolescent↗
PubMedDate not supplied

[IgG subclasses in malignant melanoma].

The 397 sera from 185 melanoma patients have been studied and classified in three groups according to the stage of disease. Our findings revealed an alteration of the level of IgG4 subclass which is related to the dissemination of disease. The percentage of abnormalities (either increased or decreased levels of IgG4) was more frequent in stage II and III (55% and 53% respectively) than in stage I (19%), The higher frequencies of high titers of IgG4 were essentially detected in advanced disease. The biological significance of the increase of IgG4 in melanoma remains obscure. It may be related to the development of facilitating antibodies of IgG4 subclass.

Humans↗
PubMedDate not supplied

[IgG levels in the sera of melanoma patients (author's transl)].

397 sera from 185 melanoma patients have been tested. We classified our subjects into three groups, according to the stage of disease. An alteration of the level of IgG 4 sub-class was found and related to the extension of the disease. The percentage of abnormalities was more frequent in stage II and III (55 p. 100 and 53 p. 100) than in stage I (19 p. 100). High titers of IgG 4 subclass were essentially detected in advanced disease. The biological significance is discussed.

Humans↗
PubMedDate not supplied

[IgG levels in the sera of melanoma patients (author's transl)].

397 sera from 185 melanoma patients have been tested. We classified our subjects into three groups, according to the stage of disease. An alteration of the level of IgG4 subclass was found and related to the extension of the disease. The percentage of abnormalities was more frequent in stage II and III (55 p. 100 and 53 p. 100) than in stage I (19 p. 100). High titers of IgG 4 subclass were essentially detected in advanced disease. The biological significance is discussed.

Humans↗