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Biomedical subjects

R Charlionet

Publications and source records attributed to R Charlionet.

At least 19 recordsLinked to original sources
PubMed1997

Oriented macroporous polyacrylamide gels.

Macroporous gels with huge cavities and partition walls result from controlled microsyneresis during gelation. In this report we show that the microsyneresis process can be further controlled: it is possible to orient the partition walls of macropores by the use of an electric field throughout polymerization. Our oriented macroporous polyacrylamide gels offer a specific structure: a set of parallel channels of about 2 microm inner diameter, with polyacrylamide walls including acidic groups linked to the aggregated matter.

Acrylic Resins↗
PubMed1996

Eliciting macroporosity in polyacrylamide and agarose gels with polyethylene glycol.

Preparation of highly porous polyacrylamide has recently been described (Righetti et al., Electrophoresis, 1992, 13, 587-595). In this report we add new observations on the conditions of promoting macroporosity in polyacrylamide gels and extend the possibility of eliciting this phenomenon to agarose matrices by the combined use of polyethylene glycol and glycerol. The process of cluster formation in hot agarose solutions was studied and gel structures were examined by scanning electron microscopy. A definition of macroporosity in gel, related to controlled microsyneresis during gelation, is tentatively proposed. The unexpected influence of acrylamide and agarose concentrations upon the size of macroporous structures in the corresponding gels is revealed.

Acrylic Resins↗
PubMed1990

Multiphasic electrophoresis with diversified spacers.

The principle and some applications of multiphasic electrophoresis with diversified spacers are described. The method combines previously published concepts of introducing highly diversified spacers into the stack of an isotachophoretic system with the theory of snow- and telescope-electrophoresis. The link between this electrophoretic method and isotachophoresis on the one hand and monophasic zone electrophoresis on the other hand is exemplified. The importance of the nature of the spacers as well as of the pH and ions in the leading and terminating zone is illustrated. Details are given concerning the experimental set-up. This electrophoretic technique could serve as an alternative to isoelectric focusing.

Blood Proteins↗
PubMed1989

Heterogeneous nature of human complement factor B: an electrophoretic approach for the analysis of its oligosaccharide chain structure and its physiological breakdown products.

Factor B is a glycoprotein which plays an essential role in the alternative pathway of complement activation. It carries the proteolytic activity of the convertases, and its physiological breakdown products Ba and Bb have some effects on the cells of the immune system. Human factor B exhibits a microheterogeneity and five isoforms are present in serum. The nature and origin of the microheterogeneity was investigated by using electrophoretic techniques. Treatments of factor B with neuraminidase and glycopeptidase F show that this microheterogeneity is mainly due to differences in its sialic acid content, varying from seven to eleven residues per molecule, and resulting in different oligosaccharide structures. However, deglycosylated factor B reveals a residual, nonallotypic variation in the Bb region of the polypeptide backbone. We confirm the presence of four asparagine-linked oligosaccharide chains of the complex type in native factor B, two of which are located in the Ba fragment, and the two others in the Bb fragment. The prevalent isoform of the native protein carries two sialic acid residues per oligosaccharide chain. Biosynthesis experiments show that the microheterogeneity of secreted factor B from HepG2 cells is acquired during the processing of its glycans. However, in vitro-secreted factor B is more heterogeneous than the serum protein. We propose a structural model for the microheterogeneity of the native protein and its physiological fragments. We discuss as well the feasibility of electrophoretic techniques to deal with microheterogeneity analysis.

Amidohydrolases↗
PubMed1988

Molecular basis for the microheterogeneity of human complement factor B.

The involvement of sialic acids in the microheterogeneity of human complement factor B was investigated. Desialylation kinetics revealed all the charge intermediates from a complex native to a homogeneous form. The relation between this heterogeneity and posttranslational events was explored in cultured hepatoma cells. Intracellular factor B exhibited the same isoelectric focusing pattern as the desialylated purified protein, whereas a highly heterogeneous form was secreted. In contrast, when N-glycosylation was prevented by tunicamycin, both intracellular and secreted forms focused like intracellular factor B from control cultures. These data lead to the conclusion that the microheterogeneity of human factor B results from different degrees of sialylation of its N-glycans.

Carcinoma, Hepatocellular↗
PubMed1986

Genetic variants of factor B in a population of Jordan.

BF phenotyping was performed in a population of Jordan. The observed allele frequencies were as follows: BF*S = 0.5457, BF*F = 0.3744, BF*SO7 = 0.0763, BF*F1 = 0.0075. These values are in agreement with the geographic position and the ethnic composition of Jordan.

Complement Factor B↗
PubMed1984

Inulin-induced activation of factor B in whole serum: description of structural modifications in the Ba fragment.

The investigation of inulin-induced conversion of human factor B in serum by isoelectrofocusing revealed physiological modifications in the primary structure of the Ba fragment. Evidence has been obtained that a nascent Ba, generated by the hydrolytic action of the D component on B in serum, was a short-lived product and that a fast release of carboxy-terminal arginine and lysine residues occurred involving a serum carboxypeptidase B enzyme.

3-Mercaptopropionic Acid↗
PubMed1984

Human alpha 1-antitrypsin genetic polymorphism: PI N subtypes.

Three new genetic variants (PI types) of alpha 1-antitrypsin are described. They have been compared to previously described phenotypes by several techniques including narrow pH range isoelectric focusing in ultrathin polyacrylamide gels. In this system, the relevant alpha 1-antitrypsin gel bands, identified by crossed immunoelectrophoresis, focused between PI M2, the most cathodal PI M subtype, and PI P BUD, the most anodal PI P subtype. They were therefore considered to be PI N subtypes. Two of them, PI N GRO and PI N YER, could not be separated by isoelectric focusing, but gave a different pattern in agarose gel electrophoresis. None of the new alleles seemed to be associated with disease. The high resolving power of isoelectric focusing is emphasized with respect to the information it may provide concerning amino acid substitutions, while the use of other techniques proved to be of utmost importance in the differentiation of other variants showing similar isoelectric points.

Electrophoresis, Agar Gel↗
PubMed1984

Genetic variants of human B component (BF system) and alpha-1-antitrypsin (PI system) in a population from Sardinia.

BF- and PI-type determinations have been performed in a population from Sardinia. The corresponding allele frequencies are as follows: BF*S = 0.5783, BF*F = 0.2189, BF*SO7 = 0.0046, BF*F1 = 0.1982 and PI*M1 = 0.5872, PI*M2 = 0.2041, PI*M3 = 0.0459, PI*M4 = 0.0940, PI*S = 0.0619, PI*Z = 0.0046, PI*N = 0.0023. Whereas the BF system shows the originality of the Sardinian population with a very high BF*F1 allele frequency, the PI system does not reveal any characteristic features.

Alleles↗
PubMed1981

Genetic variations of serum alpha-1-antitrypsin (Pi types) in Normans. Common Pi M subtypes and new phenotypes.

The results of Pi typing by high resolution isoelectric focusing on 1,030 Normans from the area of Rouen (France) is reported. The frequency of the three common subtypes of Pi M is given and new variants partly described. Pi gene frequencies are compared to previously obtained data and results from other countries. The application of high resolution isoelectric focusing to the Pi system is discussed together with the advantages it provides in the knowledge of alpha-1-antitrypsin genetic polymorphism.

Female↗
PubMed1979

Synthesis of highly diversified carrier ampholytes. Evaluation of the resolving power of isoelectric focusing in the Pi system (alpha-1-antitrypsin genetic polymorphism).

The use of condensing reagents such as epoxypropanol, diepoxyoctane, acrylamide and N,N'-methylenebisacrylamide in the synthesis of carrier ampholytes increased the diversity of amphoteric components. The quality of these synthetic carrier ampholytes has been tested in the separation of variants of alpha-1-anti-trypsin, a genetic polymorphism called the Pi system. A resolving power of the order of 0.005 pH unit was obtained.

Ampholyte Mixtures↗
PubMed1976

Genetic variants of serum alpha1-antitrypsin (Pi types) in Portuguese.

The results of Pi typing on 330 Portuguese from the area of Lisbon are reported. We found six phenotypes and four alleles out of the 24 described in the literature. The allele PiM is the most frequent as in other populations, PiS shows a high frequency (0.1152), and PiF is absent, which agrees satisfactorily with former studies carried out in Spain. These results are compared with others and the entity of the Iberian population is evoked.

Female↗