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Biomedical subjects

C M Lapière

Publications and source records attributed to C M Lapière.

At least 73 records · Page 4Linked to original sources
PubMed1988

Morphometric study of cauliflower collagen fibrils in Ehlers-Danlos syndrome type I.

The abnormal cauliflower collagen fibrils present in skin of patients with Ehlers-Danlos type I were studied by electron microscopy and computerized image analysis. The size control of the few fibrils displaying a cauliflower shape is apparently lost, eventuating in an increased amount of collagen polymers constitutive of these fibrils. This situation is fundamentally different from that occurring in dermatosparaxis, an animal disease considered as a model for Ehlers-Danlos syndrome.

Adult↗
PubMed1988

A clinicopathologic study of six cases of lipoid proteinosis.

We have reviewed the clinical and histological presentations of six cases of lipoid proteinosis. Deposits in the dermis were heterogeneous in nature and location. In the first stage of the disease's evolution, basement membrane components accumulate at the normal site of vascular, muscular, and epithelial basement membranes. Later on, lipids and amorphous material fill the superficial dermis, pushing apart the normal collagen bundles. Such deposits seem to be organized around preserved reticulin fibers. The amorphous material did not react with antibodies to collagen types I, III, IV, and V.

Basement Membrane↗
PubMed1987

Reconstituted basement-membrane matrix modulates fibroblast activities in vitro.

Cellular growth and collagen biosynthesis were compared in dermal calf fibroblasts cultured on plastic or on a reconstituted basement membrane gel, termed matrigel. This matrix, extracted from Engelbreth-Holm-Swarm tumors, consists mainly of laminin, entactin, type IV collagen, and heparan sulfate proteoglycan. The multiplication rate of fibroblasts grown on matrigel was stimulated compared to that of monolayered cells cultured on plastic, and these cells formed multilayers after 4 days. Protein and collagen biosynthesis was reduced in fibroblasts cultured on matrigel. A higher proportion of the newly synthesized collagen (40%) was incorporated to the extracellular matrix in cultures grown on matrigel than in those grown on plastic (14%). Type III collagen was the preferential collagen type deposited on matrigel, and the ratio of type III:type I collagens secreted in the medium was also slightly higher in cultures grown on matrigel. Partially processed collagen was more abundant in fibroblasts grown on matrigel than in cells cultured on plastic. Finally, cells grown on matrigel exhibited a higher catabolic activity than cells grown on plastic. In this experimental model, the reconstituted basement-membrane matrix seems to influence the activities of fibroblasts significantly.

Animals↗
PubMed1987

Acidic glycosaminoglycans, isolation and structural analysis of a proteodermatan sulfate from dermatosparactic calf skin.

Dermatan sulfate and hyaluronic acid are the major glycosaminoglycan components of dermatosparactic and normal calf skin but the ratio of hyaluronic acid to dermatan sulfate is 50-70% higher in dermatosparactic calf skin than that in normal calf skin. Hyaluronic acid in normal calf skin could be extracted to 93% of the total by NaCl and guanidine hydrochloride, while in dermatosparactic calf skin 57% of hyaluronic acid remained in the insoluble material after NaCl and guanidine hydrochloride extraction. The recovery of proteodermatan sulfate in NaCl extracts was similar in normal and dermatosparactic skin. The amount of proteodermatan sulfate extracted in guanidine hydrochloride form normal calf skin was 2-4 fold higher than that from dermatosparactic calf skin. No significant difference between dermatosparactic and normal calf skin proteodermatan sulfate could be detected in terms of size of the core protein (Mr = 55,000) by sodium dodecyl sulfate polyacrylamide gel electrophoresis, amino acid analysis, immunological cross-reactivity using polyclonal antibodies against either dermatosparactic or normal calf skin core protein, tryptic peptides or size of dermatan sulfate chains (Mr = 17,000-18,000) on gel chromatography.

Animals↗
PubMed1987

Morphometric study of cauliflower collagen fibrils in dermatosparaxis of the calves.

The abnormal cauliflower collagen fibrils present in the skin of dermatosparactic calves were studied by electron microscopy and computerized image analysis. The structure of the fibrils is heterogeneous and varies according to their location in the dermis. Cauliflower fibrils seems due to a defect in the lateral cohesion between the constitutive procollagen polymers. This is associated with the presence of a non-collageneous material larger than the aminopropeptide surrounding the procollagen polymers, while the volume occupied by procollagen in each fibril is comparable to that of collagen in normal fibrils.

Animals↗
PubMed1987

Microanatomy of the dermis in relation to relaxed skin tension lines and Langer's lines.

The microanatomy of the dermis was studied by optical and scanning electron microscopy in order to visualize the relationship between orientation of fibers and skin tension lines. In the reticular dermis of the normal adult human, skin tension lines have an anatomical counterpart consisting of a preferential parallel orientation and a straightening of thin collagen bundles and elastic fibers. This was observed only when mechanical tensions normally present in the skin were preserved during the processing of the samples, but was not observed in those that had retracted during biopsy. A comparative study of the fetal skin of calves, where relaxed skin tension lines were absent, offered further evidence that the presence of tension lines in the skin depends on the interrelationship between elastic fibers and collagen fibers, as well as on the anchorage of collagen bundles one upon another.

Adult↗
PubMed1987

Interactions between fibroblasts and a reconstituted basement membrane matrix.

A gel-like reconstituted basement membrane matrix containing type IV collagen, laminin, entactin, nidogen, and heparan sulfate proteoglycan was used to examine the interactions between normal calf skin fibroblasts and basement membranes. Within 6 h after seeding, fibroblasts initiated a migration that resulted in the formation of a cellular network after 1 day of culture on top of the gel. Electron microscopy revealed that fibroblasts were able to remodel the basement membrane matrix by penetrating into the gel (from day 3), depositing fibronectin and collagen fibers, and retracting this extracellular matrix. Fibroblasts cultured on the Engelbreth-Holm-Swarm reconstituted basement membrane matrix displayed ultrastructural features characterized by a poor synthetic apparatus (rough endoplasmic reticulum and Golgi vesicles), a large cytoskeleton, and intracytoplasmic vesicles containing laminin. Thus the reconstituted basement membrane matrix is remodeled by skin fibroblasts, and reciprocally their ultrastructural morphologic features are affected by this matrix.

Animals↗
PubMed1987

Modulation of cellular biosynthetic activity in the retracting collagen lattice.

When included in a free floating collagen lattice, several types of cells and fibroblasts attach to the collagen polymers, retract the gel, and their biosynthetic activity is repressed. Under similar conditions transformed pulmonary epithelial rat (PER) cells are unable to attach to the fibers and to significantly retract the lattice. Retraction can be induced by adding fibronectin (fn) and factor XIII (FXIII) together. This effect is fibronectin dose dependent and observed with a maximum efficiency for FXIII concentrations of 0.1 U/ml and above. Fibronectin or FXIII alone has only a limited effect on retraction. This experimental model allowed us to study the biosynthetic activity of PER cells under various degrees of cell interaction (control less than FXIII less than fn less than fn + FXIII) with their three-dimensional collagen support. The more the cells interacted with their support and retracted the gel, the more protein and collagen synthesis were reduced. This effect was observed for the products deposited in the cell layer and for those released in the medium. Increasing collagen concentration in a nonretracting lattice to a final density obtained in a maximally retracted lattice resulted in a much lower repression of biosynthetic activity. Fn and FXIII added at the same concentrations in monolayer cultures did not produce significant modification in biosynthetic activities. We propose that the regulation of the biosynthetic activity of adherent cells contracting the lattice is related to mechanical information resulting from the interactions between the cells and their support.

Animals↗
PubMed1986

Human epidermal blister: a convenient tissue for toxicological and genetic studies of benzo(a)pyrene metabolism.

Benzo(a)pyrene (BP) metabolism has been studied in epidermal blisters maintained in a culture medium for 24 h and 48 h. The viability of the cells has been assayed by [3H]proline incorporation into proteins and by [14C]BP metabolism into unconjugated metabolites. A screen of BP metabolism in 19 individuals shows a great variation of basal epidermal activity. Induction of BP metabolism by the application of coal tar 24 h before the epidermal blister sampling, resulted in two- to eight-fold increase in BP metabolism. This induction is not increased when the coal tar application is repeated.

Aged↗
PubMed1986

Defective attachment of dermatosparactic fibroblasts to collagens I and IV.

Attachment of fibroblasts from dermatosparactic sheep and cattle to collagenous substrates (types I and IV) is defective (30-50%) when compared with fibroblasts from normal or heterozygous animals. The difference was independent of the amount of substrate, incubation time and protein synthesis. No differences were observed in the binding to fibronectin or laminin. Reduced attachment to collagen can be partially restored by adding fibronectin. The polygonal morphology of dermatosparactic cells was, however, not altered by attachment and growth on dishes coated with different collagens or fibronectin. Reduced interaction with collagens could be due to changes in specific receptors and may represent a further pathological change in dermatosparactic animals.

Animals↗