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Biomedical subjects

J Font

Publications and source records attributed to J Font.

At least 271 records · Page 15Linked to original sources
PubMed1986

Serum beta 2-microglobulin as a marker of activity in systemic lupus erythematosus.

A prospective study of 62 patients with systemic lupus erythematosus (SLE) was performed in order to establish whether serum beta 2m could be a good marker of clinical activity. beta 2m was determined by radio-immunoassay and the values compared with a control group of healthy individuals. The mean value of beta 2m in the control group was 1.48 +/- 0.52 mg/l and 2.87 +/- 2.19 mg/l (p less than 0.001) in the SLE group, 4.53 +/- 2.89 mg/l in the 22 patients with active disease and 2.40 +/- 1.80 mg/l (p less than 0.001) in the 40 patients with inactive disease. High beta 2m values (greater than or equal to 3 mg/l) were observed in 64% of the patients with active SLE, VS. only 12% of the patients with inactive disease (p less than 0.001). Significant differences were also observed when beta 2m of the patients with inactive SLE was compared with the control group (p less than 0.001). The beta 2m with a sensitivity of 64%, a specificity of 87%, and an efficiency of 79% could be a good parameter to detect SLE clinical activity.

Adolescent↗
PubMed1985

Modification of the N-linked oligosaccharides in cell surface glycoproteins during chick embryo development. A using lectin affinity and a high resolution chromatography study.

Important differences in asparagine-linked glycopeptides were observed in vitro cultured fibroblasts derived from chick embryo at different stages of development. Cells from 8-day and 16-day embryos were labeled metabolically with [3H]mannose. Cell surface glycopeptides obtained after mild trypsin treatment were extensively digested with pronase and then chromatographed on concanavalin-A-Sepharose and other immobilized lectins. The most important changes concerned the complex type chains. The ratio between triantennary plus tetraantennary and biantennary chains increased about 2.5-fold from the 8th to the 16th day of development. In the same way, complex chains with bisecting N-acetylglucosamine increased from 8-day to 16-day cells as shown by Phaseolus-vulgaris-erythroagglutinin--agarose chromatography. In 16-day cells, the majority of triantennary chains (60%) with alpha-linked mannose substituted at C2 and C6 positions and biantennary chains (50%) were shown to contain fucosyl (alpha 1----6)N-acetylglucosaminyl structure in the core region by their ability to bind to a lentil lectin affinity column. Similarly, in 8-day cells, triantennary chains (50%) were more fucosylated than biantennary chains (35%). Thus, complex structures exhibited an increased fucosylation of their invariable core from the 8th to the 16th day of development, except for fucosylated triantennary chains which were retained on Phaseolus vulgaris Leucoagglutin and on lentil lectin. These latter structures were present at the surface of 8-day cells and absent at the surface of 16-day cells. After chromatography on Bio-Gel P6 and treatment with endo-beta-N-acetylglucosaminidase H, the [3H]-mannose-labeled glycopeptides were separated by high resolution chromatography into glycopeptides with complex chains and glycopeptides with high-mannose chains. Analysis of the high-mannose oligosaccharides released after endo-beta-N-acetylglucosaminidase H treatment by chromatography on Bio-Gel P4 indicated that the same type of high-mannose chains were present at the surface of 8-day and 16-day cells. Quantification of mannose, galactose and sialic acid residues using gas liquid chromatography was consistent with a decrease of the relative amount of oligomannose chains and an increase of the relative amount of complex type chains in 16-day cells compared to 8-day cells. Thus N-linked oligosaccharides derived from cell surface glycoproteins undergo changes during embryo development resulting in greater complexity of carbohydrate chains.

Animals↗
PubMed1983

Changes in protein glycosylation during chick embryo development.

To investigate the molecular changes in cell-surface glycoproteins during chick embryo development, fibroblasts from 8- and 16-day embryos were extensively digested by pronase after (i) metabolic labeling with radioactive precursors and (ii) external labeling. Two main classes of glycopeptide pronase digestion product were distinguished by Sephadex G-50 column chromatography. The large material excluded was mostly composed of glycosaminoglycans. The small retarded glycopeptides underwent age-related modifications. Those in the 8-day cells were mainly N-linked, whereas 16-day cells contained both O- and N-linked glycopeptides. The evolution of high-mannose chains in younger cells to complex-type chains in the older cells is suggested by (i) the decrease in the mannose-to-galactose and mannose-to-N-acetylglucosamine ratio with embryo development, and (ii) the fact that endo-beta-N-acetylglucosaminidase H treatment released more oligomannosyls from younger than from older embryo cell glycopeptides. Small glycopeptides were also more highly sialylated in 16-day cells than in 8-day cells. The present results provide the first biochemical evidence that both quantitative and qualitative modifications occur in cell-surface glycoconjugates during the late stages of chick embryo development.

Animals↗