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Biomedical subjects

J Labat-Robert

Publications and source records attributed to J Labat-Robert.

At least 55 records · Page 3Linked to original sources
PubMed1988

Plasma fibronectin in mammary and uterine carcinomas.

Plasma fibronectin was determined in cancer patients and in age- and sex-matched controls and analyzed as a function of age, size of tumor, receptor content of the tumor, metastases and treatment. In the control population, plasma fibronectin increased with age exponentially. The age-dependent increase in plasma fibronectin was strongly attenuated in the cancer population. As normal and cancer curves intersect at about 40-46 years, below this age cancer plasmas have slightly higher values than normal, above this age the inverse is true. No correlation was found between estrogen or progesterone receptor levels and plasma fibronectin values, nor with plasma albumin. Tumor patients with distant metastases gave slightly but significantly higher values than those with local or no metastases. No significant difference was found between tumors when Bloom grading was taken as the second parameter instead of age. The size of the tumor or the type of treatment had no influence. Increased proteolytic activity, increased trapping of plasma fibronectin in tissues and especially in the stromal (desmoplastic) reaction and/or modifications in plasma fibronectin biosynthesis may well be responsible for these results.

Adenocarcinoma↗
PubMed1987

Increased biosynthesis and processing of fibronectin in fibroblasts from diabetic mice.

Diabetic connective tissues exhibit a deranged regulation of extracellular matrix biosynthesis. Fibronectin is shown to be increased in human dermal connective tissue by immunofluorescence, mainly at the dermoepidermal and capillary basement membranes. The rate of fibronectin biosynthesis, excretion, and incorporation in a pericellular polymeric form was investigated using genetically diabetic KK mouse skin and fibroblasts as compared to Swiss and C57BL mouse skin and fibroblasts. The rate of incorporation of [35S]methionine into proteins recovered in the culture medium or in deoxycholate and NaDodSO4 or urea extracts was investigated. The rate of incorporation in the medium and deoxycholate extracts was comparable. However, the relative rate of incorporation of the tracer in the NaDodSO4-extractable, pericellular polymeric form was increased in the diabetic KK fibroblasts both for total proteins and for fibronectin. In pulse-chase experiments, the deoxycholate-soluble and NaDodSO4-soluble fractions exhibited a precursor-product relationship. The rate of passage of fibronectin from the deoxycholate-soluble (cellular compartment) form to the NaDodSO4-soluble (pericellular polymeric) form was strongly accelerated in the diabetic fibroblast cultures. These results confirm the increased rate of synthesis of fibronectin in diabetic fibroblasts as well as its processing from the cellular compartment to the polymeric pericellular form. The increase of fibronectin in diabetic connective tissues, in the matrix as well as in the basement membranes, may play a role in the mechanism of micro- and macroangiopathies and in the perturbed permeability characteristics of the diabetic capillaries, and as a glycoprotein it may contribute to the increased periodic acid/Schiff reagent staining of diabetic capillary basement membranes.

Animals↗
PubMed1987

Parallel increase of plasma fibronectin and perchlorosoluble serum glycoproteins in radiation-induced lung damage.

A study of the behavior of plasma fibronectin during a radiation-induced inflammatory lung reaction was carried out. Rats were exposed to a single homogenous thoracic irradiation of 15 Gy from a 60Co gamma source. Perchlorosoluble glycoproteins were determined (as sialic acid) as well as plasma fibronectin at 2, 8, 27, 60 and 120 days after irradiation. A parallel increase of the perchlorosoluble glycoproteins and plasma fibronectin was found. Morphological and histological studies of the irradiated lungs showed a predominating endothelial cell injury in the lung microcapillaries. The parallel increase of plasma fibronectin and perchlorosoluble serum glycoproteins suggests that plasma fibronectin can be considered as an acute phase reactant. Its early increase may be the result of the inflammatory reaction and endothelial injury induced by the radiation.

Animals↗
PubMed1986

[Macromolecules of the extracellular matrix].

In this introductory paper, the authors review the macromolecular basis of extracellular matrix. 4 principal groups of macromolecules are known: collagen, elastin, proteoglycans and structural glycoproteins. The phylogenetic evolution lead to the great complexity of this matrix. The interest of a more specific pharmacology directed towards this extracellular matrix is emphasised.

Chemical Phenomena↗
PubMed1985

Biosynthesis of laminin and fibronectin by rat satellite cells during myogenesis in vitro.

The biosynthesis of fibronectin and laminin was studied in satellite cells cultured from adult rat muscles before (day 4) and after fusion and formation of myotubes (day 14) using (35S) methionine as a tracer. The kinetics of incorporation into immunoprecipitable fibronectin and laminin were recorded at intervals from 1.5 to 24 hours of incubation with the tracer from the cells, the pericellular matrix and the culture medium. The rate of synthesis of fibronectin and laminin expressed as dpm/microgram DNA were constant from the mononucleated cell to the myotube state. Both glycoproteins were detected in the cells and in the pericellular matrix. When the results were expressed as the percentage of incorporation into total protein, major changes could be observed in the early phase of the kinetic studies in the cells and the pericellular matrix. Both showed an increase from the mononucleated myoblast to myotube, suggesting that an increasing fraction of total protein biosynthesis is directed towards these two extracellular matrix glycoproteins. At the same time, there was a decrease in the secretion into the medium of freshly synthesized radiolabeled fibronectin and laminin. Our results confirm the synthesis of varying ratios of both extracellular matrix macromolecules by undifferentiated mononucleated myogenic cells as well as myotubes.

Animals↗
PubMed1985

Fibronectin, laminin, type I, III and IV collagens in Duchenne's muscular dystrophy, congenital muscular dystrophies and congenital myopathies: an immunocytochemical study.

The distribution pattern of fibronectin, laminin, type I, III and IV collagens in human skeletal muscle was studied by immunofluorescence. In normal muscle, as well as in congenital myopathies (CM), type I and III collagens were localized in the endomysium and the perimysium. Laminin and type IV collagen delineated precisely each muscle fiber but did not stain the perimysium. In Duchenne's muscular dystrophy (DMD) as well as in congenital muscular dystrophies (CMD) the extensive proliferation of connective tissue consisted mainly of fibronectin and type I and III collagens. Laminin and type IV collagen delineated principally the basal lamina but suprisingly were found to be distributed to some extent all over the extracellular matrix. No disease--specific accumulation of components of the extracellular matrix was found which would enable us to differentiate these last two diseases, though the immunofluorescence reactions for all components were stronger in DMD than in CMD.

Adolescent↗
PubMed1985

Comparative distribution patterns of type I and III collagens and fibronectin in human arteriosclerotic aorta.

The distribution patterns of type I and III collagens and fibronectin were studied in arteriosclerotic lesions of human aortas as well as in the regions devoid of any macroscopic lesions of the same aortas. Frozen sections were analyzed for fibronectin and collagens by indirect immunofluorescence or immunoperoxidase analysis with specific antisera prepared in rabbits against human plasma fibronectin and against human type I and III collagens. Tissue samples were also stained for type I and III collagen distribution using Picro Sirius red according to the method described by Junqueira et al. (1979). In the regions devoid of any visible macroscopic lesions, there is a co-distribution in the media of the aortic wall of type I and III collagens, with a predominance of type I collagen. Type I collagen is also visible in the intima, as a continuous layer. This is attributed to an age-dependent change of the aorta (arteriosclerosis). Fibronectin can be demonstrated as a thin layer in the subendothelium and as a weak immunofluorescence over the media. In recent or evolutive arteriosclerotic plaques, fibronectin and type III collagen appear to be strongly increased and superimposed. There is also an increase of type I collagen in the intimal region of the plaque. The co-distribution of type III collagen and fibronectin in the arteriosclerotic plaques may suggest a tissue-repair-type of process, analogous to that which can be observed during wound healing. Our results suggest that in arteriosclerotic lesions, type III collagen and fibronectin are predominantly synthesized.(ABSTRACT TRUNCATED AT 250 WORDS)

Aorta↗
PubMed1984

Modifications of fibronectin in age-related diseases: diabetes and cancer.

Fibronectin is present in tissues and also in body fluids (plasma). Both forms were studied in normal controls, diabetics and cancer patients; both of these diseases show an age-dependent increasing trend. Age-dependent variations were shown to occur for both forms of fibronectin. Plasma fibronectin increases exponentially with age in a normal population. This increase is strongly attenuated or absent in diabetics and in mammary cancer patients. On the contrary, tissue fibronectin increases in diabetic skin. In mammary cancer fibronectin disappears from the tumor cell membranes but increases in the peritumoral stroma. The above modifications may be attributed to increased protease activity in tumour tissue and also to the possibility of an increased retention of plasma fibronectin in diabetic skin and peritumoral stroma, both tissues exhibiting a modification of intercellular matrix biosynthesis which does involve the increased production of retention sites of fibronectin. An increased local synthesis in both tissues may also occur. The above results are confronted with those reported by other authors and support the contention that plasma and tissue fibronectins undergo age-dependent modifications which may be seriously perturbed in diabetes and cancer.

Adolescent↗
PubMed1984

Appearance of fibronectin in putative preneoplastic lesions and in hepatocellular carcinoma during chemical hepatocarcinogenesis in rats and in human hepatomas.

The distribution of a high-molecular-weight glycoprotein, fibronectin (FN), was studied by immunohistochemical methods in putative preneoplastic lesions, as well as in fully developed hepatocellular carcinomas, formed in rats during chemical hepatocarcinogenesis, and in 10 human hepatomas. All but two preneoplastic lesions contained FN in their intercellular matrix. FN was present around groups of transformed liver cells, as well as on the surfaces and in the cytoplasms of certain cells. A similar, typically altered, distribution pattern was seen in the majority of the carcinomas studied. Six out of seven human hepatocellular carcinomas were found to contain FN. In three cases of cholangiocarcinoma, FN was, however, confined to the reactive stroma only. The presence of FN in hepatomas, which is in contrast to carcinomas of other organs, may serve as a marker for the demonstration of preneoplastic lesions of experimental carcinogenesis and for diagnostic differentiation of human hepatomas.

Adenoma, Bile Duct↗
PubMed1984

Plasma and tissue fibronectin in diabetes.

Plasma fibronectin was determined by laser immunonephelometry in controls (90 women, 66 men) and 167 diabetic patients between 10 and 60 years of age, 72 insulin-dependent males, 45 insulin-dependent females, 29 noninsulin-dependent males and 21 non-insulin-dependent females. The distribution and intensity of immunofluorescent tissue fibronectin were also studied in the patients using skin biopsies. The diabetic patients had a significantly lower plasma fibronectin level than the controls of the same age-groups and did not exhibit the strong age-dependent increase found for controls. This was true for both females and males, and especially pronounced for the insulin-dependent male patients below 45 years. The duration (less or more than 10 years), and control of diabetes (judged by the glycosylated hemoglobin A1C levels, presence or absence of retinopathy), had a lesser influence on plasma fibronectin levels, although the duration of the disease tended to increase plasma fibronectin levels. Tissue fibronectin appeared to increase as estimated by the intensity and distribution of immunofluorescence in the papillary dermis, and in vascular and dermo-epidermal basement membranes, suggesting an inverse variation of tissue and plasma fibronectin in diabetes.

Adolescent↗
PubMed1983

Immunolocalization of fibronectin and other macromolecules of the intercellular matrix in the striated muscle fiber of the adult rat.

The distribution pattern of fibronectin, laminin and type IV collagen in the striated muscle fiber of adult rat was studied using immunofluorescence staining and electron microscopy. The results indicate that fibronectin as well as laminin and type IV collagen precisely delineate each muscle fiber. Fibronectin is present on the sarcolemma extending from the cell membrane to the intercellular collagen fibers beyond the basal lamina lucida externa. This suggests a role for fibronectin in making contact between the cell membrane and the intercellular matrix.

Animals↗
PubMed1983

Investigation of intercellular matrix macromolecules involved in lichen sclerosus.

Dermal changes of the vulva in lichen sclerosus were compared with control vulvar samples using ultrastructural and immunofluorescence techniques. Collagen degeneration and regeneration were observed ultrastructurally in the superficial dermis of lichen sclerosus with increased amounts of ground substance. These processes appeared to alter the affinity of collagen fibres for the anticollagen antisera types I, III, IV. A decrease in elastin content was observed by electron microscopy. A loss of fibronectin was discovered at the dermo-epidermal junction, which looked normal ultrastructurally. The linear laminin pattern at the dermo-epidermal junction was also altered. These results suggested an enzymatic process in the pathogenesis of lichen sclerosus. Amidase activity could be determined in 6 normal and 6 pathological biopsies, though higher in the pathological samples (p less than 0.01).

Atrophy↗
PubMed1983

Distribution of fibronectin in diabetic skin.

Distribution of the fibronectin (FN) present in the forearm skin was studied in 23 controls and 34 insulin dependent diabetics. All the subjects were lean males under 50 years. After biopsy FN was studied by an indirect immunofluorescence technic. A semi-quantitative evaluation was attempted by giving a score to the fluorescent intensity read at the three following sites: vascular basement membranes, papillary dermis, and the dermo-epidermal basement membranes. We found an increased amount of FN-immunofluorescence in diabetic skins. This increase was seen not only in vascular basement membranes but also at the two other sites. No correlation was found between apparent FN levels and the duration or equilibration of diabetes. These results are consistent with other findings of the literature concerning the involvement of the intercellular matrix in diabetes.

Adult↗
PubMed1983

Immunohistochemical detection of fibronectin using different fixatives in paraffin embedded sections.

Different fixatives and immunohistochemical methods were tested for detection of fibronectin in various paraffin embedded tissues: rat kidney, spleen, gastro-intestinal tract, muscle, normal and fibrotic liver and human skin. Using cryostat sections, localisation with immunofluorescence and peroxidase technics comparable to those obtained in unfixed tissue sections, could be obtained with the following fixatives: 10% formalin in PBS containing 4% sucrose; 96% ethanol; 96% ethanol + 1% acetic acid; a series of ethanol solutions of increasing strength: 70-80-96%. These fixatives also proved to be the best for paraffin embedding. Without enzyme digestion, however, satisfactory results could not be obtained with either indirect peroxidase or immunofluorescence methods in paraffin embedded tissues. Following digestions with the enzymes at the concentrations described in the literature, the alteration of tissues made the morphological localization of fibronectin difficult. The self-sandwich peroxidase method following a gentle pepsin digestion gave results closest to those of unfixed cryostat sections; however a slight increase in background staining was observed but without interfering with the evaluation of results.

Fibronectins↗