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Biomedical subjects

L Robert

Publications and source records attributed to L Robert.

At least 19 recordsLinked to original sources
PubMed1979

Biosynthesis of skin collagens in normal and diabetic mice.

Synthesis of collagens in vitro was studied on minced mouse skins incubated with [3H]-proline in organ-culture conditions. A comparative study was carried out on genetically diabetic mice (KK strain) and control mice (Swiss strain). After incubation, neutral-salt-soluble and acid-soluble collagens were extracted. The insoluble dermis was digested by pepsin and type I and type III collagens separated by differential precipitation in neutral salt solutions. Type I and Type III collagens were characterized by ion-exchange and molecular-sieve chromatography, amino acid analysis and by the characterization of CNBr peptides. In diabetic-mouse skin, the relative proportion of type III collagen was significantly higher than in control-mouse skin. The incorporation of radioactively labelled proline into hydroxyproline of type III collagen was significantly faster in diabetic-mouse skin than in control-mouse skin. No significant modifications in the total collagen content of the skin or of their rates of synthesis were observed between the two strains. Alteration in the ratio of type III to type I collagen in the diabetic-mouse skin can be interpreted as a sign of alteration of the regulation of collagen biosynthesis and may be related to the structural alterations observed in the diabetic intercellular matrix.

Amino Acids↗
PubMed1979

Biochemical and histological analysis of bone marrow collagen in myelofibrosis.

Total protein, collagen (hydroxyproline) and glycoproteins (hexosamine) content of control and myelofibrosis (MF) bone marrow samples was determined using a sequential extraction procedure. MF marrow extracts contained higher amounts of collagen than control extracts. The collagen content appeared to increase with the duration of the disease. In more recent MF cases (less than 2 years) at least 60% of the total collagen was extracted in 0.5 M NaCl. this proportion decreases to 33% in older cases (greater than 4 years), indicating a progressive insolubilization (crosslinking) of collagen. The hexosamine content of the extracts decreased in MF as compared to controls reflecting a decrease in glycosaminoglycans (and possibly of structural glycoproteins). The reticulin content of the same bone marrows was estimated by a quantitative morphometric procedure. There was a positive correlation between the morphometrically estimated reticulin surface and the total hydroxyproline content of the marrow samples. The slopes of the least square lines correlating increase of reticulin surface to hydroxyproline content were, however, significantly different in control and MF marrows, indicating a 44% higher increase in histochemically detectable reticulin per unit increase in hydroxyproline content than in the control marrows. This result may indicate a more efficient fibrogenetic process in MF marrow than in normal bone marrow. The above results confirm the collagenous nature of the fibrous reticulin like material deposited in MR marrows and suggests a correlation between the progression of the disease and the rate of synthesis and deposition of collagen fibres.

Adult↗
PubMed1979

Influence of anthocyanoside treatment on the cholesterol-induced atherosclerosis in the rabbit.

We have studied the effect of treatment with anthocyanosides from Vaccinium myrtillis on cholesterol-induced atheroma of rabbits. We have found that the drug did not modify the serum cholesterol levels, but decreased the proliferation of the intima the extracellular matrix production the calcium and lipid deposition in the aorta, and the DNA and lipid contents. The alterations in the biochemical composition of the isolated brain microvessels were also diminished. The following mechanism may explain the protective action of the treatment: the collagen of the vessel walls participates in the control of vascular permeability. This permeability is increased by a cholesterol-rich diet. The protective drug interacts with collagen, increasing its cross-links, thus diminishing the permeability in small, as well as in large blood vessels.

Animals↗
PubMed1978

Partial characterisation of an elastase-like enzyme secreted by human and monkey alveolar macrophages.

An elastinolytic activity on soluble and insoluble elastin has been demonstrated in the culture medium of human and monkey alveolar macrophages. This activity is potentiated by latex particles in the medium. An enzyme resembling some other elastases was partially purified and characterised. It differs from other elastases in its affinity for elastin and a synthetic substrate, its susceptibility to various kinds of inhibitors and by its metal ion requirement.

Animals↗
PubMed1978

Serum elastase and its inhibitors in the blood of heavily burnt patients.

Serum elastase and its inhibitors were determined in the sera of heavily burnt patients. Serum elastase levels were elevated at two to eight days after a severe burn-accident and returned towards normal values from the 10th day on. Both alpha1-antitrypsin and alpha2-macroglobulin levels were also elevated in the sera of heavily burnt patients. alpha1-Antitrypsin showed a parallel evolution to the elastase level but alpha2-macroglobulin followed a somewhat different time curve. Plasminogen and antithrombin were not elevated significantly. It is suggested that serum elastase may play a role in tissue degradation in burnt patients.

Antithrombin III↗
PubMed1978

[Simple methods for the quantification of elastase and its inhibitors in human sera (author's transl)].

Two methods for measuring the elastase activity and the elastase inhibitory capacity of sera or other tissue extracts are described. The elastase inhibitory capacity of 40 human sera is determined using highly purified insoluble elastin in a gelified medium and this value is correlated to the alpha1-antitrypsin concentrations of these sera quantified by radial immunodiffusion. The elastase activity of these sera were determined on high molecular weight soluble kappaelastin peptides immobilized in a gelified medium and we have found a strong dispersion of the individual values. The elastase activity is not correlated either with the inhibitory capacity, the alpha1-antitrypsin or alphai-macroglobulin concentrations of these sera. The sensitivity, specificity and simplicity of these methods render them useful for their application to clinical investigations.

Elastin↗
PubMed1977

Elastase-like enzymes in aortas and human breast carcinomas: quantitative variations with age and pathology.

Two neutral proteases have been isolated from aortas and human breast tumors. The aortic elastase-like enzyme has been further purified. The details of this purification procedure will be given and some of the properties of the purified enzyme (susceptibility to various kinds of substrates, degree of inhibition of serum inhibitors, alpha 1-antitrypsin and alpha 2-macroglobulin). This elastinolytic activity of the aorta increased with age and with the degree of atherosclerosis. Both parameters seem to act independently and in a cumulative fashion. Elastinolytic activity has been demonstrated in extracts of human breast carcinomas and is exponentially related to the age of the patient. There exists a parallel neosynthesis of elastin which increased also with the age of the patient. Some characteristics of the polymeric elastin isolated from the tumor tissue will be given. The possible role of this neutral protease present in human aortas and human breast carcinomas will be discussed.

Aging↗
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↗