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Biomedical subjects

C M Lapière

Publications and source records attributed to C M Lapière.

At least 109 records · Page 6Linked to original sources
PubMed1982

[Immunolocalization of laminin, fibronectin, and collagens I to V in the normal and mastotic breast].

Our study tries by immunofluorescence to specify the nature of the connective tissue of the breasts, and especially of the scaffolding of the fatty tissue and the matrix of the lobules and of the lactiferous ducts. In consists of a study of 35 samples which were taken from 13 women whose ages ranged from 40 to 75 and whose breasts were considered on clinical examination and on radiography as normal or abnormal. We have analyzed the distribution of anti-collagen types I, III, IV and V and anti-fibronectin and anti-laminin antibodies in certain sites in the breast which were chosen because of the diversity of forms they could take from one woman to another. In each case of the distribution of protein markers seemed to be regular without, as can be found in certain cases of scar or tumour formation, a change in the distribution of the matrix proteins. Therefore, as already suggested by certain histologists, benign abnormal breast conditions (fibrosis) should be considered as simple variations from the normal. This conclusion agrees with classical histological findings.

Adult↗
PubMed1981

Significant variation in mouse-skin aryl hydrocarbon hydroxylase inducibility as a function of the hair growth cycle.

An easy, rapid and improved technique for homogenizing whole skin is described. This technique consists of reducing skin to a powder in liquid N2 by using a metallic mortar, and homogenizing the powder in a Potter-Elvehjem tube. Using this homogenizing method, we have shown that skin AHH activity in C57BL/6K and C3H/Ico mice can be induced by i.p. injected or topically applied methylcholanthrene during a defined period of the hair growth cycle, i.e. between the 8th and 14th days after depilation (Stage 6 of the anagen period). In each experimental model, there is an optimal methylcholanthrene concentration which yields a maximum induction. Topical methylcholanthrene is also responsible for a smaller aryl hydrocarbon hydroxylase (AHH) induction when the chemical is applied the same day that the club hairs are plucked. On the other hand, skin AHH activity is never induced by methylcholanthrene in DBA/2J mice, a genetically non-responsive strain. No clear-cut segregation of skin AHH inducibility levels is found among the offspring from the back-cross between (C57BL/6J X DBA/2J)F1 and non-inducible DBA/2J mice.

Animals↗
PubMed1981

Granulomatous vasculitis of Wegener.

We report a case of granulomatous vasculitis of Wegener. Systemic involvement occurred in spite of chemotherapy and concomitantly with the development of immunological disturbances. The differential diagnosis with other angiocentric granulomatoses and the estimation of the risk of extension to internal organs are primordial because of their prognostic importance.

Diagnosis, Differential↗
PubMed1980

Procollagen type III N-terminal endopeptidase in fibroblast culture.

A peptidase activity capable of excising in a single fragment the N-terminal extension of the precursor of collagen type III (p-N-collagen type III) was observed in calf tendon fibroblast culture medium. A new procedure was developed for detecting this peptidase (p-N-collagen type III peptidase). It is based on the use of 14C-labelled p-N-collagen type III obtained by carboxymethylation of the half-cystine residues with iodo-[14C]acetamide. The released labelled N-terminal extension is soluble in 27% (v/v) ethanol, whereas the uncleaved substrate and the collagen are precipitated under these conditions. The endopeptidase nature of p-N-collagen type III peptidase is supported by the similarity in molecular weight of the product of cleavage of p-N-collagen III by the enzyme to those obtained by cleavage with bacterial collagenase. An apparent Km of 0.3 X 10(-6)M was established. The pH optimum of p-N-collagen type III peptidase is similar to that of p-N-collagen type I peptidase, i.e. about 7.5. Both peptidases are inhibited by dithiothreitol and by Cu2+ and Zn2+, but not by other bivalent ions. p-N-collagen type III peptidase does not cleave p-N-collagen I or p-N-gelatin I. Partial purification of p-N-collagen type III peptidase from fibroblast culture medium was performed by sieve chromatography on Ultrogel AcA-34 to yield two peaks of activity, of mol.wts. 170000 and 100000. Part of the activity was retained on affinity chromatography on concanavalin A--Sepharose. Studied as a function of the age of the culture, p-N-collagen type III peptidase activity produced by tendon fibroblasts parallels that of p-N-collagen type I peptidase and collagen synthesis.

Animals↗
PubMed1980

Extraction and translation of collagen mRNA from fetal calf skin.

RNA was extracted from fetal calf skin by two different procedures, using phenol or guanidine hydrochloride. Poly(A)-rich RNA was separated by oligo(dT)-cellulose affinity chromatography and was further fractionated by sucrose density gradient centrifugation. When translated in an optimized wheat germ extract cell-free system, unfractionated guanidine-hydrochloride-extracted poly(A)-rich RNA directed the synthesis of two collagenase-sensitive protein bands, while phenol-extracted poly(A)-rich RNA with a sedimentation coefficient higher than 25 S was the only fraction to direct the same synthesis. On the basis of their electrophoretic mobility on a sodium dodecylsulfate/urea/polyacrylamide gel, these proteins were identified with procollagen alpha 1(I) and procollagen alpha 2. Inhibition of translation by phenol-extracted poly(A)-rich RNA with a sedimentation coefficient lower than 25 S was also observed. Guanidine-hydrochloride-extracted poly(A)-rich RNA from fetal skin directed the synthesis of three distinct collagenase-sensitive proteins in the micrococcal-nuclease-digested rabbit reticulocyte cell-free system; these seemed to correspond to procollagen alpha 1(I), procollagen alpha 2 and procollagen alpha 1 (III).

Animals↗
PubMed1979

Amino acid sequence of the aminoterminal segment of dermatosparactic calf-skin procollagen type I.

The N-terminal procollagen peptide of the pN alpha 1(I) chain from dermatosparactic calf skin contains 139 amino acid residues. For the determination of the amino acid sequence the procollagen peptide was treated with pyroglutamate aminopeptidase, protease from Staphylococcus aureus V8 and trypsin. The fragments obtained were separated by molecular sieve and ion-exchange chromatography and submitted to automated Edman degradation. The procollagen peptide consists of three segments, an N-terminal globular domain which contains all the cysteine residues and most of the hydrophobic residues present in the entire peptide, a triple helical part with a relatively high content of proline and hydroxyproline, and a short nonhelical region which forms the connection to the nonhelical region of the alpha 1(I) chain and which contains the proline-glutamine bond specifically split by the N-terminal procollagen peptidase during conversion of procollagen to collagen.

Amino Acid Sequence↗
PubMed1978

[Connective tissue diseases with cutaneous manifestation (author's transl)].

Connective tissue disorders affecting skin can be inherited or acquired and might result from an alteration of structure, function or metabolism of the constitutive elements of the supporting matrix. Collagen, the protein building the fibrous framework of the dermis, is considered as an example in understanding such a pathology at the molecular level. The molecular structure, the polymerizing capacity and the degradation of this large protein depends upon the activity of several specific post-transcriptional enzymes operating inside or outside of the cells. Pathology is known to be associated with an altered activity of most of these enzymes. Several pathological skin conditions are defined at the level of their molecular defect as in several types of the Ehlers-Danlos syndrome, osteogenesis imperfecta. Menkes' kinky hair disease, epidermolysis bullosa and scurvy. A similar molecular pathogenesis can be logically hypothesized for various other processes involving connective tissue as in scleroderma, pretibial myxoedema, cheloids, Werner syndrome, aging and corticosteroid induced atrophy.

Chemical Phenomena↗
PubMed1977

Physiopathological variations in the mechanical properties of skin.

An evaluation of the rheological properties of skin is provided by measuring "in situ" the ability of skin to withstand vertical forces of extension. In physiological conditions the biomechanical parameters are reproducible and related to age, sex, skin thickness and the microarchitecture of the connective tissue studied by scanning electron microscopy. These observations shed some light on the structure-function relationship of the fibrous framework of the connective tissue. Variation in the biomechanical parameters can be used to substantiate clinical diagnosis and to monitor the evolution and the therapy of various diseases of the connective tissue.

Adolescent↗
PubMed1976

Bone in dermatosparaxis. II. Chemical analysis.

Physical and chemical analysis of the organic matrix of dermatosparactic (D-) bone was performed to evaluate the implication of an alteration in the mechanical properties of procollagen fibers in the process of calcification. The D-diaphyseal bone contained less collagen and more hydroxyapatite than normal (N-) calf bone. Fractionated by centrifugation in a density gradient, D-bone was found to be composed of more than 80% weight of a highly calcified fraction while N-bone of the same age contained only 37% of this fraction. As compared to N-bone, the amount of organic matrix per unit volume of D-bone was increased in the least calcified fractions and reduced in the most mineralized ones. The newly formed matrix of D-bone contained an amount of collagen similar to the N-bone while the concentration of other glycoproteins was higher. Calcification was accompanied, in both types of bone, by a progressive reduction of glycoproteins and collagen; the diminution of collagen was higher in D- than in N-bone. The presence in D-bone of procollagen fibers with altered mechanical properties might be responsible for an excess of glycoproteins in the newly formed matrix. Calcium salt deposition in this matrix and progressive distension of the fibrous framework are two possible mechanisms by which hypercalcification of D-bone occurs.

Amino Acids↗