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Biomedical subjects

J Jos

Publications and source records attributed to J Jos.

At least 37 records · Page 2Linked to original sources
PubMed1983

Separation of pure toxic peptides from a beta-gliadin subfraction using high-performance liquid chromatography.

The beta v subfraction was isolated from peptic-tryptic digests of beta-gliadin by chromatography on Biogel P-10 and applied to a Lichrosorb RP-18 or a mu-Bondapak C-18 column. Fractionation was achieved using reverse-phase high-performance liquid chromatography with a linear gradient of acetonitrile in ammonium acetate. A better resolution was obtained with the mu-Bondapak column. The first-eluted peptides a, b and c1 appeared to be well purified and apparently uncontaminated. Analysis of peptides a and b showed that they contained 40 to 42% glutamine/glutamic acid, 20 to 23% proline, 14 to 16% valine and 8 to 10% leucine. They had valine as the N-terminal amino acid and their molecular mass was estimated as 5500 using sodium dodecylsulfate electrophoresis after dansylation. Peptide c1 differed from peptides a and b in containing less valine and leucine and additional amino acids such as threonine, phenylalanine and tyrosine. In addition, it had a lower molecular mass (approximately 5000) and serine as the N-terminal amino acid. Peptide b exhibited an obvious cytotoxicity for cultured coeliac jejunal mucosa at a very low concentration (0.01 g/l) and was the most toxic peptide.

Amino Acids↗
PubMed1982

The toxic fraction of gliadin digests in coeliac disease. Isolation by chromatography on Biogel P-10.

Improvement in the fractionation of gliadin digests and in the isolation of toxic fractions was achieved using chromatography on Biogel P-10. Fraction V, one of the 11 fractions eluted from a peptic-tryptic digest of crude gliadin extracted from Cappelle wheat, significantly affected coeliac jejunal mucosa in organ culture. BV, gamma V, omega V, the corresponding fractions V from beta-, gamma- and omega-gliadins, displayed similar toxic effects. Fraction VI containing peptides with a lower molecular mass did not show any significant cytotoxic activity and, moreover, inhibited the toxicity of fraction V. Analysis of the toxic fractions V showed that they contained peptides of 7-8,000 molecular mass, rich in proline and glutamine and poor in aromatic amino acids and carbohydrates. Among the various fractions, V, beta V from beta-gliadin appeared the less heterogeneous.

Amino Acids↗
PubMed1980

[Comparative toxicity of different cereals for subjects intolerant of gluten].

Coeliac disease is caused by prolamines, the storage proteins of some cereals, located in the endosperm. Cereals do not all have the same toxicity. The four wheat prolamine groups (alpha, beta, gamma and omega gliadins), visible in electrophoresis at acid pH, have been isolated and their toxicities compared by observing the morphological changes in intestinal biopsies cultured in vitro when peptic-tryptic digests of the studied proteins were added to the culture medium. The toxicity was found to be mainly located in the alpha and beta-gliadins and in peptides of 5 to 10 000 molecular weight. Peptides, resulting from peptic-tryptic hydrolysis, varied in length as a direct function of their proline content. In fact, peptide bond splitting by pepsin and trypsin is known to be blocked by proline. Thus, proline content determines peptide length and toxicity. Wheat, rye and barley toxicities were compared on the basis of a correlation between toxicity and the alpha- and beta-gliadin-like prolamine contents of these cereals. Electrophoretic estimation of alpha- and beta-gliadin-like prolamine content gave the following prediction of relative toxicity (in decreasing order): wheat, triticale, rye, barley and oats.

Amino Acids↗
PubMed1979

Immunoelectron-microscopic localization of immunoglobulin A and secretory component in jejunal mucosa from children with coeliac disease.

Using peroxidase-labelled antibodies, the ultrastructural localization of IgA and secretory component (SC) was investigated in duodeno-jejunal biopsies from six children with coeliac disease and compared with that observed in non-coelic mucosa. In normal intestinal mucosa this study confirmed the presence of IgA in the rough endoplasmic reticulum and the perinuclear space of numerous subepithelial plasma cells and one the lateral cell membranes of villous and especially crypt epithelial cells. SC was only detected in the epithelium and principally in crypt epithelium where it was identified in endoplasmic reticulum, Golgi saccules, perinuclear spaces and on lateral cell membranes. These findings support the suggestion that SC is synthesized mainly in crypt epithelium and acts as a receptor on epithelial cell membranes for dimeric IgA. In untreated coeliac patients, SC was observed at the same sites, but SC staining was reduced in damaged surface epithelial cells. The number of IgA immunocytes was increased and heavy deposits of IgA were found on basement membranes. In post-treatment biopsies, no abnormality was apparent. After re-exposure to gluten, depositions of IgA on basement membranes were the only early change. The unaltered distribution of SC and IgA in crypt epithelium strongly suggests that the epithelial transport mechanism of secretory IgA is normal in coeliac disease.

Basement Membrane↗
PubMed1976

Ultrastructural localization of IgA globulins in normal and coeliac intestinal mucosa using immunoenzymatic methods.

Using peroxidase-labelled antibodies, the ultrastructural localization of IgA immunoglobulins in duodenojejunal biopsies from children with active coeliac disease was investigated. Satisfactory penetration of conjugates was achieved by 20 hour-fixation in 4% formaldehyde and 8 hour-incubation of thick frozen sections in the presence of peroxidase-labelled anti-human alpha heavy chain antibody under continuous mild agitation. In normal duodeno-jejunal mucosa, deposits of IgA were observed at the ultrastructural level in the rough endoplasmic reticulum and the perinuclear space of plasma cells and on lateral cell membranes of villous and crypt epithelial cells. In coeliac mucosa, immuno-electron microscopic studies confirmed the increased cell density of IgA immunocytes and revealed heavy deposits of IgA on the basement membrane of surface epithelial cells and the wall of neighbouring blood vessels.

Animals↗
PubMed1975

In vitro pathogenetic studies of coeliac disease. Effects of protein digests on coeliac intestinal biopsy specimens maintained in culture for 48 hours.

Jos, J., Lenoir, G., de Ritis, G. & Rey, J. In vitro pathogenetic studies of coeliac disease. Effects of protein digests on coeliac intestinal biopsy specimens maintained in culture for 48 hours. Scand. J. Gastroent. 1975, 10, 121-128. Intestinal biopsies from controls and from children with treated or untreated coeliac disease were cultured for 48 hours in the presence or absence of various peptic-tryptic (P.T.) or peptic-tryptic-chymotryptic (P.T.C.) digests of gliadin and casein, using a modified organ culture method. In flat biopsy specimens obtained from children with active coeliac disease and maintained in culture in the presence of P.T. or P.T.C. digests of gliadin, whether autoclaved or not, a cytotoxic effect was obvious; but this effect was in part unspecific, since P.T. digests of casein were also slightly noxious in such experimental conditions. Biopsies from controls or from children with coeliac disease in remission were not affected by the presence in culture medium of casein or gliadin digests, whereas coeliac biopsies, also obtained from patients in remission but after gluten challenge, were specifically injured during culture with gliadin peptides. On the other hand, a thorough P.T.C. hydrolysis of gliadin abolished all its in vitro noxious effects, suggesting that its toxicity is related to a relatively large peptide.

Biopsy↗