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Biomedical subjects

J Labat-Robert

Publications and source records attributed to J Labat-Robert.

At least 73 records · Page 4Linked to original sources
PubMed1982

[Distribution of fibronectin in the skin of patients with scleroderma].

The distribution of fibronectin (FN), a major glycoproteic component of extra-cellular matrix, has been studies by an indirect immunofluorescence technique in the skin of 50 normal controls and 19 sclerodermic patients. In the normal skin, FN was present mainly in the papillary dermis, as thin strips and less abundant in reticular dermis, bound to collagen bundles. In scleroderma skins, FN was increased in the deep dermis of extensive and evolutive lesions (11 cases). In an other hand, the distribution of FN was not modified in stabilized lesions (8 cases). We conclude that the detection of FN in the scleroderma skin is an useful marker of the activity of the systemic sclerosis process and we discuss the possible role of FN as a primary matrix for organization of the collagenous connective tissue during the sclerosing process.

Extracellular Space↗
PubMed1982

[Distribution of fibronectin in renal pathology (author's transl)].

The distribution of fibronectin (FN), a major glycoproteic component of extracellular matrix, has been detected in the human kidney by an indirect immunofluorescence technique using a rabbit anti-human FN serum on 6 embryonic renal tissues, 5 normal kidneys and 120 renal biopsies. In the metanephros, FN was seen within tubular basement membranes and in embryonic glomeruli. There was a progressive loss of tubular basement membrane staining during the differentiation of renal parenchyma. In the normal kidney and in kidneys with nephritis without endo- and/or extracapillary proliferation, FN was localized only in the mesangium and faintly in capillary walls of glomeruli. In glomerulonephritis with endo- and/or extracapillary proliferation, FN was increased around mesangial cells. FN was also bound to fibrin in epithelial crescents, fibrinoid necrosis and in thrombi of thrombotic microangiography. FN was increased in the mesangium of diabetic glomeruli without endocapillary proliferation. FN has not been found in amyloid deposits and in sclerosed glomeruli. We therefore conclude that FN is a good mesangial marker and is probably involved in the inflammatory process.

Diabetic Nephropathies↗
PubMed1981

Fibronectin-like protein in Porifera: its role in cell aggregation.

Experiments were carried out on a freshwater sponge (Ephydatia mulleri) in order to demonstrate the presence of fibronectin in Porifera. By using antibodies to highly purified human plasma fibronectin, the presence of a similar or identical protein could be demonstrated in the membranes of E. mulleri cells such as epithelial cells, fibroblast-like cells, and choanocytes. The reaction was specific, could be abolished by the addition of excess fibronectin, and was not observed with nonimmune rabbit serum. The immune fluorescent reaction became stronger when the sponge cells were pretreated with acetone and could also be observed, although with a less intense staining, on the intercellular matrix. This shows the predominant presence of a sponge fibronectin-like protein in the cell membranes and also its presence to a lesser extent in the intercellular matrix. When dissociated sponge cells were led to reassociate under the microscope, reassociation could be completely inhibited by anti-human fibronectin antiserum up to a dilution of 1:120 and partially inhibited up to a dilution of 1:240. The reassociation of dissociated sponge cells could also be inhibited by the addition of purified gelatin but not with serum albumin or with a normal, nonimmune rabbit serum. These results clearly indicate that a sponge cell fibronectin-like protein may play an important role as the (or one of the) recognition site(s) of the aggregation factor(s) and can therefore be directly involved in cell association, morphogenesis, and differentiation.

Animals↗
PubMed1981

Trehalase activity in genetically diabetic mice (serum, kidney, and liver).

Trehalase activity was determined in serum, liver, and kidney in alloxan treated Swiss mice and in homozygous (Ob/Ob, Db/Db) and heterozygous (Ob/+, Db/m+) diabetic mice. Both alloxan and genetic diabetic mice exhibited a large increase in serum and liver trehalase activity with no change in kidney trehalase activity. The heterozygotes (Ob/+, Db/m+) showed only a slight increase of enzyme activity. Further quantitative differences were noticed between the genetic and alloxan diabetic animals. The liver enzyme activity increased from 10- to more than 20-fold in the liver of the homozygous Ob/Ob and Db/Db strains and only 3-fold (not significant compared to controls) in the alloxan treated animals. The above results suggest a regulatory relationship between the genes coding for trehalase and the enzymes of glucose metabolism activity involved in the development of the metabolic anomalies of diabetes. The structural gene for trehalase may well have survived elimination of selective pressure during phylogenesis and remained part of a co-regulated group of glucose metabolising enzymes. This could explain its sensitivity to mutations affecting glucose metabolism and its sensitivity to insulin directed regulatory mechanisms.

Animals↗
PubMed1980

Loss of fibronectin in human breast cancer.

The distribution of fibronectin was studied in normal human breast tissue and in breast tumors. In normal tissues and in benign tumors, fibronectin was present in basal laminae and on the cellular surfaces of myoepithelial and secretory cells. A partial loss of (pericellular) fibronectin was seen in atypical dystrophies, and a complete disappearance of pericellular and basement membrane-bound fibronectin was observed in invasive adenocarcinoma.

Adenocarcinoma↗
PubMed1980

[Distribution of fibronectin in normal human tissue].

Distribution of fibronectin (FN), a major glycoproteic component of extracellular matrix was studied by an indirect immuno-fluorescence technique using a rabbit anti-FN serum on frozen sections of fresh human tissues. In the extracellular matrix, FN is localized in epithelial and glandular basement membranes (bronchial, digestive, urothelial, prostatic, thyroid and mammary glands). FN is also visualized in vascular basement membranes and pulmonary alveolar basal laminae. In lymphoid tissues. In the liver and adrenal cortex, FN has the same distribution as reticulin fibers. In the kidney, glomerular mesangium in labeled. There are also pericellular labelings on fibroblastic and muscular cell surfaces. Epithelial cells of the mammary gland show a pericellular positive staining. FN is principally involved in cell orientation and in cell extra-cellular matrix interactions.

Fibronectins↗
PubMed1979

[Gastric mucus glycoproteins : structure, functions and pathology (author's transl)].

O-glycosylated glycoproteins are the main constituents of gastric mucus. They are responsible for its viscosity and for its gel-forming properties. Recent advances accomplished over the last years on its physical and chemical characterization are briefly reviewed. Many issues remain still unsettled concerning the modification of its structure and composition in diseases as well as details of its biosynthesis and its pharmacology.

Animals↗
PubMed1979

Quantitative evaluation of the in vitro biosynthesis of gastric mucus glycoproteins. Standardization of the methodology.

For the evaluation of a normal or pathological function of gastric mucosa, a reproducible method for the estimation of the biosynthesis of mucus glycoproteins appears to be necessary. Rat gastric mucosal scrapings incorporate in vitro several labeled compounds such as 14C-U-D-glucose, 35SO4, 14C-I-L-fucose and L-G-3H-proline in glycoproteins similar to those synthetized in vivo by native mucosa. The aim of our present work is to describe in detail the procedure we use and to show its reproducibility in 9 separate experiments. Secreted glycoproteins (fraction II) and intracellular glycoproteins (fraction III) obtained during a 4 hours in vitro incubation of rat gastric mucosal scrapings at 37 degrees C in standardized conditions were separately studied. The protein and hexose contents, total incorporated radioactivity and specific radioactivity (cpm/mg protein) were determined in these two fractions. The protein content of fraction II from 2 rat gastric mucosal scrapings incubated in 5 ml was 2 mg +/- 0.4 SEM and its hexose was 38.7 mg per 100 mg protein +/- 3.9. Fraction III contained 6.3 mg protein +/- 1.3 and 15.7 mg hexose per 100 mg protein +/- 3.5. About 27% of the total radioactivity incorporated (from 14C-glucose) was in fraction II (+/- 2.6 SEM) and 73% (+/- 2.6 SEM) in the cell bound fraction III. The distribution of total radioactivity was quite similar to that of total proteins : about 25% proteins were in fraction II and 75% in fraction III with a SEM of about 5 to 10% of the average value. If the biosynthetic activity is expressed as specific radioactivity, i.e. the ratio of incorporated radioactivity to mg proteins, the average for both fraction II and fraction III was about 10,000 cpm/mg protein and the standard error of the mean values are +/- 5.2% of the mean for in vitro secreted mucus glycoproteins (fraction II) and 9.1% in the case of intracellular glycoproteins (fraction III). These values can be considered as a satisfactory index of reproducibility of the method of mucosal scrapings if performed as described above.

Animals↗
PubMed1978

Comparative specificities of trehalases from various species.

1. Using derivatives or non-symmetrical analogs of alpha,alpha-trehalose, we studied the catalytic specificities of trehalases from various species: Pseudomonas fluorescens, Melolontha vulgaris, porcine and human kidneys. 2. alpha,Beta-trehalose, beta,beta-trehalose, 6,6'dideoxy alpha,alpha-trehalose, alpha-D-xylopyranosyl alpha-D-xylopyranoside were shown to be neither substrates nor inhibitors. 3. 6'deoxy alpha,alpha-trehalose, alpha-D-glucopyranosyl alpha-D-xylopyranoside, alpha-D-allopyranosyl alpha-D-glucopyranoside and alpha-D-galactosyl alpha-D-glucopyranoside, which all possess an intact alpha-D-glucopyranosyl residue, were split by all these trehalases. 4. alpha-D-glucopyranosyl alpha-D-mannopyranoside, alpha,alpha-trehalosamine are competitive inhibitors. 5. These results show the importance of the primary alcohol group at C-6, of the equatorial configuration of the OH groups at C-2, C-3 and C-4 and of the modification of the structure at C-2 of the substrate for the catalytic activity.

Animals↗
PubMedDate not supplied

Effect of in vitro aging on the modulation of protein and fibronectin biosynthesis by the elastin-laminin receptor in human skin fibroblasts.

The 67-kD elastin-laminin receptor (ELR) subunit which carries the recognition site for elastin peptides (EP) is a lectin. Its binding with galactosides can modulate the kinetics of its interaction with its ligand, EP. In this study the biosynthesis of proteins, collagen and fibronectin were evaluated in the presence of agonists and antagonists of the receptor on human skin fibroblasts. The biosynthesis of total proteins determined by 3H-proline incorporation and of fibronectin (by immunoprecipitation) were shown to increase with passage number. The presence of 1 microg/ml kappa-elastin (EP) in the culture medium increased both total proteins and fibronectin biosynthesis. Melibiose, an agonist of the receptor at 5 microg/ml (140 microM), decreased both proteins and fibronectin biosynthesis in the culture medium of human skin fibroblast at the 10th and 15th passage. These results show that the ELR can control the biosynthetic mechanisms of some of the macromolecular constituents of extracellular matrix such as fibronectin and moderate its age and passage-dependent upregulation.

Cells, Cultured↗
PubMedDate not supplied

Modifications of the biosynthesis of type-I and type-III collagens and fibronectin during diabetes and atherosclerosis.

Results show that diabetes, which is a major risk factor for arterio-atherosclerosis, mimicks an accelerated aging, at least as far as the thickening of basement membranes and fibronectin and collagen biosynthesis are concerned. A similar sequence of events could be demonstrated in human atherosclerotic plaque formation. In conclusion, we could demonstrate a disregulation of extracellular matrix components biosynthesis (type-III collagen and fibronectin) in diabetes and atherosclerosis.

Aged↗
PubMedDate not supplied

[Gastric mucus glycoproteins: structure, functions and pathology (author's transl)].

O-glycosylated glycoproteins are the main constituents of gastric mucus. They are responsible for its viscosity and for its gel-forming properties. Recent advances accomplished over the last years on its physical and chemical characterization are briefly reviewed. Many issues remain still unsettled concerning the modification of its structure and composition in diseases as well as details of its biosynthesis and its pharmacology.

Chemical Phenomena↗