Search PubMed⌕ Search

Biomedical subjects

L Robert

Publications and source records attributed to L Robert.

At least 271 records · Page 15Linked to original sources
PubMed1977

Structural glycoprotein from the media of pig aorta. Aggregation of the S-carboxamidomethyl subunits.

Media of pig aorta was extracted with 1 M NaCl and 2 M MgCl2 to remove most of the soluble collagen, proteoglycans and glycoproteins. The glycoproteins remaining in the residue were extracted with 6 M urea-0.1 M mercaptoethanol. The urea soluble proteins were precipitated by dialysis, redissolved in 4 M guanidine-0.05 M DTT and were S-carboxamidomethylated (CM-guanidine extract). This extract was further fractionated by a variety of methods in order to separate a glycoprotein from collagen and proteoglycans. Caesium chloride density-gradient ultracentrifugation of the CM-guanidine extract separated a minor proteoglycan peak from a major glycoprotein fraction still containing some hydroxyproline. This major glycoprotein fraction was excluded as a single peak from Sephadex G 100 and G 200 in 4 M guanidinium chloride or in 6 M urea-0.2 per cent SDS. Sodium dodecylsulphate gel electrophoresis separated this high molecular weight Sephadex fraction into a major low molecular weight (approximately 35000 daltons) component and a minor high molecular weight component. This glycoprotein fraction could also be separated from a collagenous fraction and from proteoglycans by ion exchange chromatography on DEAE cellulose or by gelfiltration on Sepharose 4 B in 6 M urea-0.02 M EDTA-0.2 per cent SDS at pH 7.0. The isolated glycoprotein fraction is rich in dicarboxylic amino acids, contains galactose, mannose, (glucose), N-acetylglucosamine and sialic acid. The S-carboxamidomethyl glycoprotein preparation interacts with acid soluble calf skin collagen on isoelectric focusing in sucrose gradient in urea. This interaction is in favour of the biological role claimed for structural glycoproteins during fibrogenesis and differentiation.

Amino Acids↗
PubMed1977

Elastogenesis and elastinolytic activity in human breast cancer.

Polymeric elastin was isolated and chemically characterized from 34 human breast cancers. There exists a good correlation between the histological and biochemical determinations of elastin; the breast cancer elastin resembles the other elastins isolated from ligamentum nuchae or aorta. Meanwhile it differs by its lower proline content and by its degree of crosslinking as determined by the ratio (Des + IDes/4)Lys. An elastinolytic activity (elastase) was found in human breast cancer extracts. This activity increased with the elastin content of the tumors.

Amino Acids↗
PubMed1977

Matrix biology and pathology, a new branch of biomedical sciences.

The macromolecules of the intercellular matrix (MM) : collagen, elastin, proteoglycans and structural glycoproteins) are present in all tissues in variable amount and proportion. Some tissues, particularly rich in MM are designated as "connective tissues". Matrix macromolecules assure the integration of cells in tissues and of tissues in organs and in the whole organism. Differentiation, morphogenesis, maturation and aging are characterized by the variation of the raltiave rates of synthesis of individual MM-s. Several post-transcriptional and post-translational steps play an important role in biosynthesis of MM-S offering a multitude of possibilities for genetic and/or aquired anomalies. Recent progress in the descriptive and dynamic biochemistry of MM-s sheds new light on these anomalies which condition a whole class of diseases (the diseases of the intercellular matrix or matrix pathology). The molecular and cellular mechanisms of several of these diseases start to be understood. As the great majority of the important disease of occidental societies (such as vascular and articular diseases, diabetes, and the pathology of aging) belong to this category, intensive research in matrix biology and pathology as well as of its teaching in the medical curriculum should be considered as first priorities.

Chemical Phenomena↗
PubMed1976

[Correlation between age, arteriosclerosis and elastinolytic activity of human aorta wall].

An elastolytic protease was isolated recently from human and animal aortic wall. We report here the positive correlation between the activity of human aortic elastase, the degree of atherosclerosis and age. These two parameters appear to influence independently and in an additive fashion the level of aortic elastase. There appears to be an increasing synthesis and/or liberation of aortic elastase with age. This process is accelerated in the presence of arteriosclerosis. It appears probable that the increasing elastolytic activity is mainly responsible for the fregmentation and lysis of the elastic fibers with age and arteriosclerosis as observed with histochemical techniques.

Aging↗
PubMed1976

[Acute diffuse bullous epidermal necrolysis (Lyell's syndrome). Etiopathogenic aspects and therapeutic contribution].

A case of Lyell's syndrome in a patient of paediatric age is presented complete with iconography organized according to the chronological sequence of skin manifestations. The aetiopathogentic aspects are discussed, from the importance of pharmacotoxic factors to that of bacterial or viral agents and unknown factors. The possible immunological or genetic mechanism that may play a part are also examined. The histological picture is described and the personal therapeutic approach is commented on. This is suitable for everyday clinical practice and consists of local dermato-oculo-protective treatment, rehydration and antishock treatment, and anti-infective and nutritional measures.

Child, Preschool↗
PubMed1976

Age dependence of the biosynthesis of intercellular matrix macromolecules of rabbit aorta in organ culture and cell culture.

The age dependence of the relative rate of biosynthesis of intercellular matrix macromolecules was studied in organ culture and cell culture obtained from aortas of newborn, young and adult rabbits. In organ culture there was a strong decrease with age of the rate of incorporation of (14C)-lysine and (3H)-glucosamine in all macromolecular fractions. Neosynthesis of elastin could be demonstrated by the isolation of labelled demosine at all ages. In cell cultures derived from newborn and adult aortas, no decrease in total incorporation was noticed. The pattern of synthesis and secretion of glycosaminoglycans and glycoproteins did however change with age. These results suggest the existence of matrix-dependent and of a matrix-independent regulation of the relative rate of synthesis of matrix macromolecules.

Aging↗
PubMed1976

Characterization of lipids associated with macromolecules of the intercellular matrix of human aorta.

Macroscopically lesion-free parts of human aortas with no or light lesions (group I) and advanced atherosclerotic lesions (group II) were submitted to a series of successive extractions in order to "solubilize" all the macromolecular components of the arterial wall ("chemical dissection"). Lipids were extracted with methanol-chloroform from all these macromolecular fractions and analyzed for cholesterol, triglycerides, phospholipids. The fatty acid composition of the separated fractions was determined by GLC. The lipid composition and fatty acid spectrum of the macromolecular fractions of group I and group II aortas was compared. Total lipids increased in the freely extractable ("non associated lipids, approximately 78% of total) fraction as well as in the fraction "associated" with collagen and elastin. Free and esterified cholesterol increased also both in the "freely extractable" and in the collagen-elastin-associated lipids", approximately 78% of total) fraction as well was higher (+ 100%) than that of free cholesterol (+ 60%). Triglycerides increase also by 15 to 70% in all fractions except in the elastin-associated fraction. Free fatty acids increased by 40 to 400% in all extracts associated with macromolecular fractions but not in the "freely extractable" fraction where they decreased. Phospholipids show less marked variations (approximately less than 10%) and decrease in the elastin associated lipids of group II aortas. The fatty acid spectrum of group II lipids associated with macromolecules differs from that of group I. There is a relative increase of longer chains (C greater than 18, especially 20:1 and 20:2 acids). No such increase in the "long" fatty acids was seen in the "freely extractable" lipid fraction. Elastin isolated from group II aortas is significantly enriched in total lipids, cholesterol (free and esterified) and free fatty acids and contains the widest spectrum of fatty acids (from 11:2 to 22:1) with a significant fraction of total fatty acids as "odd" carbon chains. There appears to be a correlation between the decrease of triglyceride-bound fatty acids and the increase of free fatty acids. The free fatty acid concentration exceeds both in group I and II aortas the concentration of fatty acid esters. This increase in free fatty acids "associated" with intercellular matrix macromolecules and especially with elastin may be the result of an increased hydrolysis of esters and/or a decreased esterification in advanced atherosclerotic aortas. The accumulation of long chain and "odd" fatty acids in elastin may be an important factor in its accelerated degradation during the atherosclerotic process.

Aorta↗
PubMed1976

Biochemical and ultrastructural study of human diabetic conjunctiva.

Combined biochemical and ultrastructural study of conjunctival biopsies of 27 normal subjects and 45 diabetics (40 to 60 years old) was made. The "in vitro" incorporation of 14C-glucosamine and 3H-proline in freshly excised conjunctival biopsies was studied. The alterations of the capillary basement membrane of the conjunctiva were studied by electron microscopy. The following results were obtained: 1) A decrease of the specific activity of 14C-glucosmaine incorporation was found in fractions of diabetic conjunctiva. 2) In diabetic conjunctiva the percentages of 3H-proline incorporation in polymeric collagen containing fraction and structural glycoproteins containing fraction were significantly increased with a parallel decrease of 3H-proline incorporation in "crude soluble collagen" fraction expressed as a percentage of total incorporation. 3) Significant thickening of capillary basement membrane was observed with the appearance of collagen-like fibrils within the basement membrane in diabetic conjunctiva. Such fibrils were not seen in normal basement membranes. A relation between the extent of basement membrane thickening and the appearance of collagen-like fibrils is suggested. 4) The higher percentage of incorporation of 3H-proline in polymeric collagen may be related to the appearance of collagen fibrils in thickened basement membranes of the diabetic conjunctival capillaries. 5) These results suggest an abnormal regulation of the relative rate of biosynthesis and/or excretion of intercellular matrix macromolecules (collagen, structural glycoproteins) as part of the metabolic disorders characterising diabetes.

Adult↗
PubMed1976

Biochemical studies on dacron arterial prostheses.

Dacron arterial prostheses, treated or not with biopolymers (gelatin, glycosaminoglycans) were implanted in the abdominal aorta of dogs and the connective tissue synthetised inside and outside the prosthesis was studied. After 3 and 9 months of implantation the prosthesis, a joining portion and a piece of aorta were excised and put in organ culture with 14C-lysine for 3 days. Representative macromolecular extracts were then obtained by a "chemical dissection" procedure. The radioactivity and the chemical composition of these extracts was studied. The DNA content of the prosthesis was higher than that of the adjacent aorta showing a dense cellular repopulation of the prosthesis. This was confirmed by histology also which revealed the presence of a newly formed limiting elastic membrane and the presence of numerous elastic fibrils. Collagen, elastin and glycosaminoglycans could be detected in the macromolecular extracts showing that the cells which repopulated the prosthesis expressed a complete biosynthetic capacity as far as matrix macromolecules are concerned. The distribution of proteins in the extracts was as follows: 4% of total proteins were extracted in a 1M CaCl2-buffer 80% of total proteins in the collagenase extracts, 10% in the 6M urea extract. Only 0,2% of proteins were in the final elastase extract, 10 times less than in the joining aorta fragment. The proportion of the other proteins was similar in aorta and in the prosthesis as well as the chemical composition (hexosamine and hydroxyproline content) of the extracts. The proportion of collagenase-extractable proteins decreased with the time of implantation (from 3 to 9 months) and the proportion of urea-extractable proteins increased. This type of modification is similar to that found in aging aorta wall. 14C-lysine was actively incorporated in all macromolecular fractions studied. The incorporation pattern of the prothesis tissue was similar to that found for the joining host aorta, showing a similar regulatory tendency for matrix macromolecules. It appears therefore that a valid hemocompatible vascular type of connective tissue can be synthesised on the dacron arterial prosthesis and nature of this connective tissue can be influenced by previous biopolymer treatment of the synthetic prosthesis. The described procedure (incorporation of labelled precursors in organ culture) appears to be a valid method for the exploration of the regulatory processes underlying the synthetic capacity for matrix macromolecules of the newly formed tissue in the synthetic prosthesis.

Animals↗
PubMed1976

[Structural and biochemical alterations of human diabetic dermis studied by H-lysine incorporation and microscopy].

The alteration of the structural organization of dermal connective tissue was studied by light and electron microscopy and by biochemical techniques in normal human and in diabetic patients using skin biopsies. Part of the tissue was used for light and electron microscopy, the rest was incubated in the presence of 3H-lysine for four hours. The 3H-lysine labelled biopsies were submitted to a sequential extraction procedure in order to obtain representative macromolecular fractions containing the matrix macromolecules. The extracts were analyzed for their chemical composition and radioactivity. Electron microscopy revealed ultrastructural modifications of the fibroblasts, of the collagen and elastic fibers in the diabetic dermis. Fibroblasts contained an increased amount of electron dense deposits in the cytoplasm and dilated endoplasmic reticulum. The collagen bundles were dissociated. Elastic fibers under the epithelial basal laminae were fragmented or absent. The incorporation pattern of 3H-lysine into these macromolecular fractions was different in the normal and diabetic skin biopsies. The percentage of total radioactivity incorporated increased significantly in the 1M CaCl2 extractable fraction an in the 6M urea extractable fraction and decreased significantly in the collagenase and elastase extracts in diabetic skin biopsy. These results demonstrate the existence of morphological and biochemical alterations in diabetic connective tissue (dermis) reflecting alterations in the relative rates of synthesis and/or degradation of the intercellular matrix macromolecules as well as of their microarchitectural arrangement.

Adolescent↗
PubMed1976

Action of human hyperlipemic sera on the biosynthesis of intercellular matrix macromolecules in aorta organ cultures.

Explants from rabbit aortic media were incubated in MEM medium supplemented with 14C-lysine and with 10 p. 100 hyperlipemic (type IV and V) or normal human serum respectively. The incubated fragments were extracted at increasing ionic strength. The insoluble collagen and elastin were hydrolysed with collagenase and alcoholic potassium hydroxyde respectively. The radioactivity was determined in the extracts and the radioactive labelling profile of proteins was investigated on polyacrylamide gel electrophoresis in SDS. With the exception of the collagenase extract (polymeric collagen) the incorporation of the radioactivity into insoluble collagen is not altered or increases. These the incubation was carried out in the presence of hyperlipemic serum. Incorporation of the radioactivity into insoluble collagen seems not to be altered. These results show a decreased protein synthesis with a relative increase in the biosynthesis of polymeric insoluble collagen in the aortic media incubated in the presence of hyperlipemic serum.

Adult↗
PubMed1976

Biosynthesis of elastin and other matrix-macromolecules in veinous arterial prosthesis.

Homologous saphenous veins where implanted in the arterial circilation (femoral artery) of dogs for various times (1 to 9 months, most data given for 3 months). After this period, the in vitro biosynthesis of intercullar matrix macromolecules was studied by incubating the veins in organ culture conditions in the presence of 14C-lysine for 3 days. A fractional extraction procedure was used to obtain representative macromolecular extracts for the determination of chemical composition (hydroxyproline, hexosamines) and radioactivity. Neosynthesis of elastin was considered as valid criteria for the adaptation of the veinous wall to the new (arterial circulatory) conditions. The chemical composition of the grafted veins was different from that of the nongrafted, controlateral saphenous veins suggesting a molecular remodeling of the grafted veinous wall. Radioactive lysine was incorporated in all macromolecular fractions of grafted and control veins. The specific radioactivity of the extracts obtained from grafted veins was higher than that obtained from the control veins. The only exception was the collagenase extract (containing mainly the polymeric collagen) which had a somewhat lower radioactivity in the grafted vein. The incorporation of lysine in the elastin fraction increased by a factor 10 in the grafted vein as compared to the non-grafted veins. Radioactive desmosine could be demonstrated in the elastin fraction. It appears therefore that the veinous wall could adapt its biosynthetic capacity to the new circulatory conditions by increasing considerably the biosynthesis of elastin. This is accompanied by an increase of the synthesis of other macromolecules and a significant remodeling of the macromolecular structure of the vessel wall.

Animals↗