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Biomedical subjects

M Fontaine

Publications and source records attributed to M Fontaine.

At least 127 records · Page 7Linked to original sources
PubMed1983

[Experimental swine influenza. Comparison of the pathogenicity of swine-type wild influenza viruses and strains of human type H3 N2 whose reservoir is swine].

Intra-nasal inoculation of 10-day-old piglets, free of specific pathogenic flora, with swine influenza virus A/H1 N1 and A/H3 N2 produces lesions of viral pneumonia without detectable clinical signs. Following indirect contamination all the strains studied were able to multiply in the respiratory tract; in those cases where no macroscopic lesion was seen, microscopic examination revealed variable modification of the pulmonary tissue depending on the virus causing infection. Influenza virus type H3 N2 are naturally found in many groups of pigs and can therefore play an important role in the respiratory pathology of the hog. Experimental results when compared to findings in the field indicate that the severity of the disease is linked to associated etiological factors as well as to the virulence of the viral strains themselves.

Animals↗
PubMed1983

[Epizootic swine influenza on animal farms in Brittany].

Since 1976, seroepidemiological surveys using radial haemolysis and isolation trials from samples collected from pigs at the abattoir showed that Brittany was an important reservoir of swine subclinical infections due to the human Influenza A viruses H3N2. Influenza A H1Sw N1Sw subclinical infections sporadically occurred from 1979 to 1981. In January 1982 an epizootic started in Finistère which spread from west to east. The H1Sw and N1Sw antigens of 28 stains isolated from 1979 to 1982 were studied with ferret and rabbit anti sera and appeared to be variants of the previous strains (1976-1967-1961-1930). A reinforced serological survey in pigs demonstrated that both Influenza A viruses H1Sw N1Sw and H3N2 simultaneously spread in herds. There is no actual prove of recent human infections by A H1Sw N1Sw virus.

Adolescent↗
PubMed1982

[Possible action of riboflavin (vitamin B2) as a chemical telemediator in aquatic ecosystems (author's transl)].

The attractive action of riboflavin at certain concentrations on the young Salmon (parr) has been demonstrated. This property diminished or disappears with smoltifications. Owing to the emission of riboflavin by the young Salmon, the possibility, at diverse migratory or sedentary phases of the biological cycle, of an action of a pheromone or ecomone type, is discussed.

Aging↗
PubMed1982

Structure-function relations in the third component of human complement (C3)-I. Hydrophobic site.

Charge shift electrophoresis and crossed hydrophobic interaction immuno-electrophoresis were used to demonstrate the presence of hydrophobic sites in the human C3 molecule. C3b and C3d were true amphiphilic proteins that could bind to hydrophobic surfaces. To the contrary, native C3, that presented the characteristics of amphiphilic proteins upon charge shift electrophoresis, did not bind to hydrophobic surfaces. These results suggested that the hydrophobic sites were located in the internal part of the C3 molecule and they were exposed in the external part when C3 was activated. The action of chaotropes on C3 was studied in detail and showed that the hydrophobic sites protected the thiolester bond (present in the labile site) from hydrolysis by water and thereby preserved the biological properties of native C3.

Binding Sites↗
PubMed1982

Deleted IgG1 and IgG2 H chains in a patient with an IgG subclass imbalance.

The serum of a female patient studied over 7 months initially showed, in addition to normal residual IgG, two abnormal IgG proteins and in the last 3 months of the disease showed only one abnormal IgG protein. Gm typing and serological subclass determinations revealed an imbalance of allelic forms within the IgG1 subclass during the disease. The IgG2 level remained markedly elevated throughout the study. The two abnormal IgG-related proteins were devoid of light chains. The abnormal gamma cathodic immunoglobulin and the abnormal beta 2-immunoglobulin were Fc-like and covalently disulphide linked, with molecular weights of 60,000 daltons (N terminal, SER) and 72,000 daltons (N terminal, GLY) respectively. The first belonged to the IgG1 subclass and the second to the IgG2 subclass. No abnormal proteolytic activity was noted and plasma cells reacted with anti-gamma-chain antisera only. We hypothesize that the molecular defect leading to the deleted chains was an early event, preceding the differentiation into plasma cells which produced the two IgG1 and IgG2 deleted H chains.

Chromatography, Gel↗
PubMed1982

Effect of normal and cystic fibrotic serum on ion transport and mucus glycoprotein secretion from the isolated rabbit trachea.

It has been argued that individuals with cystic fibrosis (CF) might be expected to lead reasonably normal lives if the secondary changes associated with the disease could be eliminated or overcome. The purpose of this study was to characterize the electrical and transport properties of the isolated rabbit trachea in the presence and absence of control or CF serum. In addition, we sought to determine whether the presence of CF serum resulted in an alteration in either the amount or type of mucus glycoprotein secreted by the trachea. It was found that both control and CF sera inhibited the short-circuit current of the rabbit trachea due primarily to an inhibition of active sodium transport. The effect was irreversible and could be abolished by heating the serum prior to the experiment and was only observed when the serum was on the luminal surface. There was no differential effect between control or CF serum. Investigation also indicated that exposure of the isolated trachea to CF sera had no effect on the amount of mucus glycoproteins as indicated by the degree of sulfation in secretion samples eluted from DEAE cellulose following exposure to CF serum. It is possible that alterations in the type of mucus secreted subsequent to exposure to CF serum might relate to the turbidity of the mucus seen in such patients.

Animals↗
PubMed1981

Evidence for alpha-1-acid glycoprotein populations of different pI values after concanavalin A affinity chromatography. Study of their evolution during inflammation in man.

Isoelectric focusing in polyacrylamide gel was used to reveal the two alpha 1-acid glycoprotein populations separated by affinity chromatography on Con A-Sepharose from human purified alpha 1-acid glycoprotein, whole normal serum and sera from patients undergoing an acute inflammatory process. The concanavalin A non-reactive peak had a lower isoelectric point than did the concanavalin A reactive peak. Moreover, crossed immunoaffinity electrophoresis with free concanavalin A revealed three alpha 1-acid glycoprotein populations (concanavalin A reactive, weakly and non-reactive). A significant difference was observed between the patterns of normal and of inflammatory sera, since the concanavalin A reactive fraction was enhanced during the inflammatory process. These results suggest a variation in relative ratios of the different types of peripheral oligosaccharide branches in the alpha 1-acid glycoprotein populations.

Chromatography, Affinity↗
PubMed1981

A redox function for the Calpha2 domain of IgA immunoglobulin.

IgA1 populations were reduced over a range of dithiothreitol concentrations and the products were examined by sodium dodecyl sulfate polyacrylamide gel electrophoresis and peptide mapping. The study showed that IgA was more resistant to reduction than other immunoglobulin classes (IgG, IgM). SDS-polyacrylamide gel electrophoresis showed that intersubunit bond and H-L bond were the most labile disulfide in polymeric and monomeric IgA, respectively. Peptide mapping revealed that the itrachain disulfide of the C alpha 2 domain was more or equally sensitive to the reduction than H-L and intersubunit bonds. Electrochemical experiments demonstrated that this bond had redox properties and the possibility involving disulfide exchange is discussed.

Chemical Phenomena↗
PubMed1981

Differential binding of IgG subclasses to enzyme-treated human lymphocytes.

Human erythrocytes coated with each of the four human IgG subclasses were used to detect Fc gamma receptors on human peripheral blood lymphocytes (HPBL). Rosette formation was obtained only with erythrocytes coated with IgG3 (EA gamma 3). Neuraminidase treatment of HPBL induced rosette formation with EA gamma 1, EA gamma 2, and EA gamma 4 complexes. Pronase treatment also induced rosette formation to a lesser extent, but abolished EA gamma 3 rosetting. Trypsin treatment enhanced EA gamma 3 rosette formation. These phenomena occurred on both 'T' and 'non-T' lymphocytes. Erythrocytes coated with small quantities of IgG 3 did not form rosettes with HPBL. Neuraminidase treatment enhanced their binding, whereas pronase did not. These two phenomena occurred only on non-T lymphocytes. Rosette formation with EA gamma 1 was also obtained with lymphocytes stimulated in vitro with mitogens. After 2 days of culture, stimulated lymphocytes expressed receptors that were able to bind both EA gamma 1 and EA gamma 3 complexes. These results suggest the existence of cryptic receptors for IgG1, IgG2, and IgG4 that could be disclosed by neuraminidase and pronase treatment and exposed on stimulated lymphocytes. A hypothesis of one or several Fc gamma receptors is suggested.

Animals↗
PubMed1980

[Augmentation of HL-A A9 antigen in malignant melanoma, principally in metastatic or recurrent forms. Apropos of 105 cases of melanoma of which 34 were serious forms].

HLA-A and B phenotypes of 105 patients suffering from malignant melanomas were determined, with special regard for metastatic form or relapse. A highly significant increase of the HLA-A9 antigen is seen (X2 = 17.47); such data had already been shown by van Wijek [2], but other authors did not find this abnormality when studying melanomas whose histologic form was not specified.

HLA Antigens↗