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Biomedical subjects

G Bellon

Publications and source records attributed to G Bellon.

At least 127 records · Page 7Linked to original sources
PubMed1988

Purification and characterization of phospholipase A2 inhibitory proteins from pig thyroid gland.

A 32 kDa phospholipase A2 inhibitory protein was isolated from pig thyroid gland after calcium precipitation and fast protein liquid anion-exchange chromatography. SDS-polyacrylamide gel electrophoresis revealed the purity of the protein. The protein activity was assessed by the inhibition of pancreatic phospholipase A2 on [3H]oleic acid-labelled Escherichia coli membranes as substrate and on the prostaglandin E2 production of cultured thyroid cells. The amino acid composition and the isoelectric point were quite similar to those of endonexin previously described in other tissues or cells. The cross-reactivity of a polyclonal antibody against a 32 kDa lipocortin from human peripheral blood mononuclear cells with our thyroidal 32 kDa protein confirmed its lipocortin nature. Before the purification by fast protein liquid chromatography, the Ca2+ pellet contained lipocortin I (35 kDa and its core protein 33 kDa) identified by its cross-reactivity with a polyclonal antibody.

Amino Acids↗
PubMed1988

Demonstration of human kidney differentiation antigens with monoclonal antibodies.

Six human differentiation antigens (EE24.6, EG9.11, EG14.1, EI16.1, EK8.1, EK17.1) have been defined using monoclonal antibodies obtained from mice immunized with embryonic kidney cells. Their histologic distribution was determined on frozen sections of embryonic, fetal, and adult human kidneys by immunofluorescence assay. EE24.6, an ureteral bud marker, was detected only on the germ layer of mature kidney urothelium. EG9.11 and EG14.1 were detected on the S-shaped bodies and also on the adult proximal convoluted tubule for the former and the glomerular basement membrane for the latter. EI16.1, a marker of condensed mesenchyme, was detected only on epithelial cells of adult proximal convoluted tubule. EK8.1 was found in the mesangium, connective tissue, and with particularly dense labeling in the basement membranes. This labeling pattern was present throughout renal organogenesis. EK17.1 recognized both cell and plasma human fibronectins. Staining for all antibodies was nearly identical in mesonephros and metanephros. These results demonstate that some antigens follow their embryonic destiny. They indicate an antigenic similarity between the mesonephros and the metanephros and, therefore, a very early appearance of these antigens. During differentiation, these antigens concentrate on more defined structures, and staining became increased with an increased degree of differentiation.

Antibodies, Monoclonal↗
PubMed1988

[Mucoviscidosis: what is the cause of bronchitis?].

To this day, there is no explanation as to why chronic airway obstruction develops in cystic fibrosis (CF). Even if the mucous secretions are considered abnormal, these abnormalities resemble those observed in patients without CF. There is no primary alteration of the ciliated cells and the presence of a CF ciliary inhibitory factor has not yet been established. However, the electrolyte (chloride and sodium) transport abnormalities in airway epithelia can induce a dehydration of bronchial secretions and a slowdown of mucociliary transport in peripheral airways. But this does not explain the specific lung infection and the role of Pseudomonas aeruginosa. No specific biochemical or structural abnormality of the CF-specific bronchial secretions and/or cell membranes has yet been identified. The question therefore remains open: are we dealing with a deficient respiratory tract immunity? The CF coding gene has been localized: could the discovery of a "basic defect", a direct expression of the abnormal gene, explain the electrolyte transport abnormalities, the specific lung infection and other CF manifestations?

Acute Disease↗
PubMed1988

[Mucoviscidosis: a genetic disease of adulthood].

Mucoviscidosis (cystic fibrosis of the pancreas) is the most frequent lethal genetic disorder in the white race. It is an autosomal recessive transmission. In spite of its recent localisation on the 7th chromosome, the fundamental mechanism responsible for the symptoms remains unknown and it is still a syndrome more than a disease. It presents as a generalised seromucous exocrinopathy. The serous glands are functionally abnormal and have secretions too rich in chloride which allows for the sweat test (the only test of diagnostic value). The accumulation of abnormal mucous secretions is responsible for the clinical manifestations: intestinal troubles, bronchial and pulmonary disease, progressive pancreatic insufficiency and biliary cirrhosis. Mucoviscidosis is not longer a disease exclusively of children. The treatment which is solely symptomatic has profoundly changed the prognosis. Half of the children afflicted become adults. This fact and the better condition of diagnosis explain the appearance of a new symptomatology sometimes with a late presentation. On the basis of the genetic and prognostic implications one should consider the diagnosis at any age even if the general state is well conserved. The diagnosis rests on the association of suggestive symptoms and a disturbed sweat test. In the adult the presenting signs are always respiratory, more rarely digestive, and sometimes sterility. These associations are very suggestive. The current evolution requires a specific clinical management of new adult cases who, even if not in a very good clinical state, maintains a vital hope for several years with symptomatic treatment (and the hope perhaps that the discovery of the fundamental defect will lead to more specific therapy).

Adult↗
PubMed1987

Collagen activates superoxide anion production by human polymorphonuclear neutrophils.

Human polymorphonuclear neutrophils (PMNs), purified on Ficoll-Hypaque cushions, were incubated for 5 min with calf skin acid-soluble collagen and the released superoxide anions (O2-) measured spectrophotometrically by reduction of ferricytochrome c or by chemiluminescence analysis. This collagen stimulated the release of O2- unless it had been treated with pepsin. The stimulatory activity remained in denatured collagen, was contained only in the alpha 1(I) chain and was present in the alpha 1(I)-CB 6 (CNBr-cleaved) peptide, which is C-terminal. The activity was linearly dependent on the collagen concentration up to about 200 micrograms/ml. In addition, this collagen induced a release of beta-glucuronidase and N-acetyl-beta-glucosaminidase from PMNs.

Calcium↗
PubMed1987

Effects of preformed proline and proline amino acid precursors (including glutamine) on collagen synthesis in human fibroblast cultures.

A technique of derivatizing proline and 4-hydroxyproline with 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole was used to measure the radioactivities, concentrations and specific activities of proline and hydroxyproline. The technique was used to study the conditions of procollagen synthesis in cultured human foreskin fibroblasts. Procollagen synthesis appeared to be independent of the proline concentration in the medium, in the presence of glutamine, when monitored by the assay of non-dialyzable hydroxyproline, but not when monitored by [14C]proline incorporation. In the absence of unlabelled proline added to labelled proline in the medium, the specific activity of the secreted procollagen did not reach a plateau over a 24-h period. When the medium was supplemented with glutamine, glutamic acid, or aspartic acid, both the radioactivity and concentration of intracellular free proline decreased. Pyrrolidone-2-carboxylic acid and ornithine both induced a slight increase in concentration of the intracellular free proline. Glutamine competed with [14C]proline for incorporation into prolyl-tRNA and procollagen, independently of free intracellular proline, and it stimulated the biosynthesis of procollagen (expressed as non-dialyzable hydroxyproline) by a factor of 2.3.

Amino Acids↗
PubMed1987

[Lack of transformation of the collagen substratum in collagen lattice cultures].

Human dermal fibroblasts were seeded into collagen lattices (tridimensional meshwork) of two preparations: (1) acid-extracted, (2) pepsin-digested-calf skin collagens. Lattices prepared with pepsin-digested collagen retracted faster during the first 2 days, then the two preparations gave the same contraction pattern. Lattices of both preparations were contracted for up to 23 days and their collagens submitted to CNBr treatment. The patterns of CB-peptides were found identical for all the incubation periods tested. There is no formation of cross-links during the contraction process.

Acetates↗
PubMed1985

Immunohistochemical localisation of macromolecules of the basement membrane and extracellular matrix of human gliomas and meningiomas.

The distribution of type I, III, IV and V collagen in 35 gliomas and 20 meningiomas was studied by indirect immunofluorescence staining. In addition, the presence of fibronectin (FN) and laminin (LN) is also reported. In gliomas expression of type IV collagen and LN was found in the vessel walls and associated with the endothelial glomerulus-like proliferations. FN and type V collagens were located in proliferating vessel walls in a pattern corresponding both to the basement membrane and the perivascular matrix around the vessels. In the extracellular matrix of grade III and IV gliomas occasional faint intercellular fluorescence was also observed with both FN and type V collagen. Type I and III collagens were localised in the vessel walls and in the perivascular connective sheet. Glioma cells did not express any of the antigens investigated. In meningiomas, type IV and V collagens, LN and FN were found in vessel walls, whorls formations and psammoma bodies. These stainings support the hypothesis of a vascular origin of these psammoma bodies which were only found in syncytial and transitional meningiomas. Both type I and III collagens were detected in the perivascular connective tissue. In general, meningioma cells and extracellular matrix did not express any of these molecules, except in transitional meningiomas where occasional fluorescence was observed in extracellular matrix with type V collagen and FN.

Basement Membrane↗
PubMed1985

Quantification and specific detection of collagenous proteins using an enzyme-linked immunosorbent assay and an immunoblotting for cyanogen bromide peptides.

A method for the detection of collagenous proteins within cyanogen bromide digests of tissues has been devised. The peptides produced by digestion with cyanogen bromide were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and transferred to a nitrocellulose filter. They were stained on the filter by incubation first with antibodies to collagen and then with a second antibody covalently linked to horseradish peroxidase, 4-chloro-1-naphthol was added, and the bound enzyme was assayed. This procedure is useful for the identification and characterization of collagens of types I, III, IV, and V in tissues. In addition, we have developed a sensitive and specific competitive enzyme-linked immunosorbent assay (ELISA) which is convenient for quantifying collagens (types I, III, and IV) in tissues. In this kind of assay, soluble cyanogen bromide peptides compete with cyanogen bromide peptides adsorbed onto a solid-phase support for rabbit anti-collagen antibodies. We determined the amount of bound antibody by using goat anti-rabbit immunoglobulin G covalently conjugated to horseradish peroxidase and then provided a substrate for the enzymatic reaction. The sensitivity range of the ELISA is 0.09 micrograms/ml in the region of 90 to 10% binding.

Animals↗
PubMed1985

A study of collagen metabolism in cell cultures by fluorometric determination of proline and hydroxyproline.

A technique of derivatization of proline (Pro) and 4-hydroxyproline (Hyp) by 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole permitted the measurement of Pro and Hyp radioactivities, concentrations, and specific activities in the main fractions separated from cultures of fibroblast cells (extracellular collagen and non-collagen proteins, intracellular free Pro and Hyp, Pro- and Hyp-containing peptides, procollagen, and non-collagen proteins). The evaluation of collagen in the medium was obtained from as few as 10(4) cells. The method might advantageously replace [14C] Pro or [3H] Pro incorporation studies. It permits measurement of the size of the Pro pool and the amount of peptides formed by intracellular catabolism of collagen. It demonstrates that the time necessary for a full equilibration of intracellular Pro and intracellular collagen is longer than is generally believed. It avoids the uncertainties of protein labelling, which may vary with uncontrolled variations of the intracellular Pro specific activity.

4-Chloro-7-nitrobenzofurazan↗
PubMed1985

Inhibition of collagen production in scleroderma fibroblast cultures by a connective tissue glycoprotein extracted from normal dermis.

It was shown in a previous paper that a connective tissue glycoprotein (CTGP) extracted from normal rabbit dermis was able to inhibit total protein and collagen syntheses by normal dermis fibroblast cultures. In the present study, the effects of CTGP on scleroderma fibroblasts were investigated. [14C]Proline incorporation into total proteins of the supernatant was not significantly different from that found in controls. By contrast, the amount of collagen, expressed as percentage of total secreted protein, was far higher in scleroderma cultures than in normal ones (14.4% +/- 6.0% vs 4.6% +/- 0.9%). Addition of CTGP to the medium induced a concentration-dependent inhibition of [14C]proline incorporation into proteins from both control and scleroderma cells. In control cultures, no significant decrease of the percentage of collagen was observed, but over 60 micrograms/ml, both cytotoxic effects and inhibition of protein synthesis occurred. In scleroderma cultures, the inhibition was twice as effective on collagen as on noncollagen protein synthesis. The inhibition of collagen secretion was not related either to changes in collagen hydroxylation or to the intracellular catabolism of newly synthesized procollagen.

Animals↗
PubMed1985

[Vascular collagens. General review].

The analysis of vascular collagens proved difficult due to high insolubility. In the seventies, compositional studies concerned a fraction of 30% of total collagen. Type I collagen, far less soluble than type III, was not fully extracted, resulting in an overevaluation of type III collagen. When the proportions of collagens are measured on the totality of the material, type I collagen represents 60%, type III, 30% and the remaining 10% are constituted by type V and minor collagens. Atheromatous plaques contain a little more collagen than normal arteries and the proportion of type I remains 60%. Whereas several experiments demonstrated that slices of atheromatous arteries in vitro synthesize more collagen than slices of normal arteries, the possible mechanism of interaction between plasma lipoproteins (normal or abnormal) and collagen metabolism remains unknown. Vein and capillary collagens have been rarely studied. Basement membrane collagen does not seem to be increased in quantity in the thickened basement membrane of diabetic patients capillaries.

Animals↗
PubMed1984

Immunohistochemical localization of macromolecules of the basement membrane and the peritumoral stroma in human laryngeal carcinomas.

Forty laryngeal carcinomas were studied by immunofluorescence with specific antisera against components of the basement membrane (type IV collagen and laminin) as well as antisera against connective tissue antigens (type V collagen and fibronectin). The basement membrane surrounding well-differentiated squamous cell carcinomas showed an appearance similar to that seen beneath normal epithelium. In contrast, marked alterations of the basement membrane were constantly observed around infiltrating and poorly-differentiated carcinomas. The staining of connective tissue components in most cases was as intense in carcinomas as in normal laryngeal mucosa. The use of antibodies to basement membrane components may help to elucidate the mechanism of invasion of connective tissues by malignant cells.

Basement Membrane↗
PubMed1984

Separation and evaluation of the cis and trans isomers of hydroxyprolines: effect of hydrolysis on the epimerization.

A procedure has been developed which can detect the hydroxyproline isomers trans-4-hydroxyproline (Hyp), trans-3-hydroxyproline, cis-4-hydroxyproline, and cis-3-hydroxyproline present in hydrolysates of collagens. The method involves hydrolyzing collagen, and reacting the primary amino acids with o-phthaladehyde (OPA) and the hydroxyprolines and proline with 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl) which combines specifically with secondary amino acids. The proline and hydroxyprolines are then separated by thin-layer chromatography and quantified by using a scanning spectrofluorometer. The method was used to show that both trans-4-L-hydroxyproline and trans-3-L-hydroxyproline were epimerized as a function of hydrolysis time to the cis isomers. An appreciable amount of trans-3-Hyp was degraded. Hydrolysis with 6 N HCl in the presence of 6% trichloroacetic acid gave greater epimerization than the 6 N HCl alone. Alkaline hydrolysis in 0.2 M Ba(OH)2 caused more epimerization of trans-4-Hyp and trans-3-Hyp compared with acid hydrolysis but less degradation, so that alkaline hydrolysis is proposed for the evaluation of trans-3-Hyp, provided that the total of the cis and trans isomers be considered in this case.

Chromatography, Thin Layer↗
PubMed1984

Distribution of type IV collagen in benign and malignant epithelial proliferations. An indirect immunofluorescence study on the breasts, the lungs, and the skin.

The distribution of type IV collagen in benign and malignant epithelial proliferations of the breasts, the lungs, and the skin was studied by an indirect immunofluorescence technique using specific antiserum. In benign lesions of the breasts, the staining for type IV collagen was present in all vascular and glandular basement membranes. In basal cell carcinoma of the skin, the basement membrane labeling was also found to be continuous. In malignant lesions of the breasts, the lungs, and the skin, staining for type IV collagen was seen only around well-differentiated glandular structures and in close contact to basal epidermal cells. This staining appeared as an irregular network. Of particular interest was the localization of type IV collagen in non-infiltrating lesions of the breasts and the bronchi where discontinuity in the basement membrane staining was observed. In contrast, there were no disruptions of basement membrane labeling in skin senile keratosis and in Bowen's disease. We conclude that the loss of type IV collagen seen in malignant proliferations in our study is related to overt or potential tumor cell infiltration and aggressiveness.

Basement Membrane↗