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Biomedical subjects

A Chamson

Publications and source records attributed to A Chamson.

At least 37 records · Page 2Linked to original sources
PubMed1995

Effects of gamma-alumina and hydroxyapatite coatings on the growth and metabolism of human osteoblasts.

The behavior of human osteoblasts cultivated on hydroxyapatite or alumina-coated disks of Ti6AL4V was studied in vitro. Cell anchorage and spreading were observed by scanning electron microscopy. Cell growth was monitored by counting cells and measuring DNA at 5 h and 2,5, and 10 days after cell seeding. Cells grown for 10 days were labeled with 14C-proline and total protein and collagen synthesis were measured; the type of collagen was also determined. Both ceramics showed excellent biocompatibility. At 10 days of culture the cells showed a higher rate of proliferation on alumina than on hydroxyapatite. Neither ceramic altered the collagen biosynthesis or the osteoblast-like properties of the cells, as indicated by the high percentage of type I collagen.

Aluminum Oxide↗
PubMed1995

Collagen biosynthesis in cell culture from chorionic villi.

After chorionic villus biopsy of human placenta, cell cultures were propagated with Ham's F10 medium or Eagle's minimum essential medium (MEM). It was possible to study the morphology of the cells by transmission electron microscopy (TEM) after a special culture of the cells in a collagen gel. The cells embedded in a collagen gel were able to contract the gel and to organize collagen fibres, as fibroblast cultures do. TEM showed vacuolization and well-developed cisternae of the endoplasmic reticulum, especially in the case of MEM culture. The aim was to determine whether cells cultivated from early placenta were able to synthesize enough collagen for a metabolic study. A high level of collagen biosynthesis could be quantified. Types I and III collagen can be determined which is useful for studying the abnormalities of collagen synthesis in suspected cases of osteogenesis imperfecta or Ehlers-Danlos type IV syndrome. The hydroxylation of lysine can also be studied with respect to Ehlers-Danlos type VI syndrome. Moreover, these cells, in contrast to fibroblast cultures, made it possible to study the biosynthesis of type IV collagen.

Cells, Cultured↗
PubMed1995

Effect of a gonadotropin releasing hormone analog on an experimental ovarian tumor: direct and indirect actions.

An ovary autotransplanted into the spleen of a bilaterally ovariectomized rat develops into a luteoma, which grows under constant gonadotropin hyperstimulation. The effect of a long-acting GnRH agonist (GnRH-a), on tumor growth and hormone secretion was investigated. Two experimental models were used: Model 1: GnRH-a (0.33 mg/rat sc) or estradiol valerianate (50 micrograms/rat sc injected once a week for four weeks) was administered simultaneously with ovary implantation; Model 2: the drugs were administered after 1 month of tumor development. The treatment with estradiol was used as a control of tumor regression. Saline injected ovarian grafted rats and Sham operated animals were used as controls. In Model 1: The GnRH-a significantly inhibited tumor development (Positive tumors: Saline: 100% vs GnRH-a: 43%, p < 0.01). In Model 2: the GnRH-a and estradiol significantly reduced the volume of one month old tumors (52% and 39% of initial volumes respectively, p < 0.01). Gonadotropin secretion was significantly inhibited or its increase blunted by the GnRH-a and by estradiol treatments in both models. Estradiol and progesterone in portal blood, which collects the steroids secreted by the luteoma, were significantly reduced by GnRH-a treatment in both models. On the other hand, in tumor cells cultured "in vitro", the GnRH-a was able to inhibit the LH induced progesterone secretion in a concentration dependent way. These results clearly show that the GnRH-a is effective in inhibiting tumor growth or reducing its volume, when already developed; furthermore, it suppresses tumor steroid hormone production. These actions were exerted at both the hypophyseal and tumor levels.

Animals↗
PubMed1995

Collagen bioassay by the contraction of fibroblast-populated collagen lattices.

The ability of fibroblasts to induce contraction of a collagen gel was studied with respect to the quantity and the quality of type I acid-soluble collagen. The speed of contraction and the appearance of the fibre bundles obtained after contraction depend not only on the ratio of the amount of collagen to fibroblasts but also on the process of the collagen purification. When collagen lattices made with a pepsinized collagen were compared to lattices made with a non-pepsinized collagen of the same amount, the fibres from pepsinized collagen seemed fewer (only 13% of the observed surface against 51% in the case of non-pepsinized collagen) and the lattices appeared by electron microscopy to be almost empty as if the lattices were comprised of less collagen. The importance of the non-helical domain of the collagen molecule for the identification and organization of collagen by fibroblasts is discussed. Collagen retained by fibroblasts was maximum (80-99%) when collagen was prepared in the presence of protease inhibitors and decreased when proteolysis was not avoided, for example when collagen was prepared in the presence of pepsin. A test using an estimation of the percentage of collagen retained by fibroblasts in a contracted collagen lattice is proposed to check the biological quality of collagen samples.

Acetates↗
PubMed1992

[Synthesis and supramolecular organization of components of the extracellular matrix by fibroblasts cultured in a collagen lattice].

Fibroblasts cultured in a collagen gel contract and organize the gel into a three-dimensional matrix of collagen fibers. Within this matrix, the fibroblast cell cycle is blocked at the G1 phase but also at the G2 phase. The fibroblasts produce the main extracellular matrix components (collagen, noncollagen proteins, glycosaminoglycans), although in small amounts. Studies using this in vitro model with radiolabeled precursor substances (14C proline, 3H glucosamine) demonstrated production of supermolecular complexes which resisted to proteolysis by pepsin and collagenase and could not be isolated by saline precipitation. Polyclonal antibodies identified type I collagen, type VI collagen and fibronectin in this coherent supermolecular structure. The presence of glycosaminoglycans was also demonstrated by alcian blue precipitation.

Cells, Cultured↗
PubMed1990

[Behavior on de-epidermized human skin of unspecified reconstituted collagen tissue].

The aim of our study was to assess the behaviour of a despecified collagen tissue laid on desepidermized human skin (taking area of skin graft). The collagen tissue was prepared according to Bell's method. The collagen was latticed, contracted by fibroblasts, chemically treated (formaldehyde or glutaraldehyde) to stabilize the fibrils and then despecified by cialit treatment. This tissue laid on superficial, non infected wounds very rapidly took a necrotic appearance and was totally lysed after 10 to 12 days without any modification of the healing course. No bacterial infection was observed. Histological and ultrastructural studies showed desorganization of collagen fibre bundles and tissue invasion by inflammatory cells. Circulating antibodies to collagen were absent at day 30. This model lacks interest as a substitute for superficial tissue replacement, but a healing function could be assigned to its high chemotactic power for polynuclears and macrophages and should allow its use in cases of deep tissue loss.

Aged↗
PubMed1989

Study of basement membrane formation in dermal-epidermal recombinants in vitro.

Two different dermal-epidermal recombinants were prepared in vitro and used to study the synthesis and formation of basement membrane. The first was obtained by culturing keratinocytes on the surface of a collagen lattice populated by fibroblasts. The second was prepared by coculture of both keratinocytes and fibroblasts in a collagen lattice. After 6 weeks of culture, the basal lamina was observed with electron microscopy only if keratinocytes were cultivated on top of the collagen lattice populated by fibroblasts. In the second model, however, type IV collagen, laminin, and pemphigoid bullosa antigen could be detected by immunofluorescence as well as synthesis of type IV collagen in the culture, but no basement membrane was observed by electron microscopy. These data demonstrate that, in vitro, basement membrane formation depends not only on the presence of the macromolecular components but also on the culture conditions.

Basement Membrane↗
PubMed1989

Collagen and lipid biosynthesis in a case of epitheliogenesis imperfecta in cattle.

An analysis of the dermis and a study of collagen and lipid biosynthesis by fibroblast cultures were carried out in one case of epitheliogenesis imperfecta in a new born calf. This was found to be not only an epidermal disease with fissures and blisters within basal cells on the basement membrane but also a metabolic disease affecting the dermal fibroblasts. These fibroblasts showed a significant decrease in collagen biosynthesis with an increase in the percentage of type III collagen and also a decrease in the biosynthesis of lipids, especially glycerides and cholesterol.

Animals↗
PubMed1989

Collagen biosynthesis anomalies in prolidase deficiency: effect of glycyl-L-proline on the degradation of newly synthesized collagen.

Prolidase deficiency is a rare hereditary disease characterized by an iminodipeptiduria especially composed by glycyl-L-proline which is not further degraded. The study of collagen metabolism in fibroblast cultures from three prolidase-deficient patients showed an increase in the rapidly degraded collagen and a decrease in the proline pool. In order to elucidate the mechanism of this metabolic disturbance, glycyl-L-proline was added to the cell cultures. In the control cultures, the addition of this dipeptide caused an increase in the rapidly degraded collagen and a decrease in the proline pool. The effects on the patient fibroblasts depended on the severity of the deficiency. The metabolic function of the dipeptide glycyl-L-proline was discussed in the light of these results.

Adult↗
PubMed1988

Collagen biosynthesis in a case of infantile myofibromatosis.

Cells from a skin nodule from a patient with a recurrent form of familial myofibromatosis were cultivated in vitro. A metabolic study showed that these cells behaved like fibroblasts with collagen synthesis, a normal percentage of type III collagen, hydroxylation rate and the ability to contract a collagen gel. The main disturbances were the decreased synthesis and increased cell multiplication rate after a lag phase. This behavior was compared with that of a fibroblast culture from normal skin.

Collagen↗
PubMed1987

Collagen biosynthesis and isomorphism in a case of Ehlers-Danlos syndrome type VI.

Collagen metabolism was studied in fibroblasts grown from a skin biopsy specimen of a patient who presented the striking clinical features of Ehlers-Danlos syndrome and, in particular, hyperextensibility of the skin, hypermobility of the joints, and kyphoscoliosis. A reduction in lysine hydroxylation, characteristic of Ehlers-Danlos Type VI, was observed after labelling of the collagen with 14C-proline and 3H-lysine. Other modifications in the collagen metabolism of fibroblast cultures were noted, including an increase in collagen and total protein synthesis, and an increase in both the Type I and Type III collagen. The percentage of Type III collagen was, however, lower than in the control fibroblasts. The results point out the complexity of collagen disturbances in Ehlers-Danlos Type VI.

Adult↗
PubMed1987

Collagen biosynthesis in a case of epidermolysis bullosa dystrophica recessiva.

Collagen metabolism was studied in fibroblast cultures from a patient presenting an epidermolysis bullosa dystrophica recessiva (EBDR) syndrome characterized, in particular, by blistering below the basal lamina observed by electron microscopy. The previously described increase in collagen production was confirmed and several other qualitative modifications of the secreted collagen were observed, including an underhydroxylation of lysine, a decrease in the type III/type I collagen ratio, and an increase in the rapidly degraded collagen. On the other hand, these fibroblasts were able to organize and contract collagen to form a dermal equivalent like normal fibroblasts. Normal keratinocytes can grow and form an epidermal sheet on the surface of these dermal equivalents including normal or pathological fibroblasts.

Cells, Cultured↗
PubMed1986

Acceptance of a connective tissue equivalent for grafting and capsuloligamentary reconstruction.

A strip of a connective tissue equivalent prepared by using the patient's fibroblasts cultivated in vitro and calf skin collagen, was used for capsuloligamentary reconstruction of the knee. The study of the humoral and cell-mediated immune responses indicated that there was no cell-mediated immune reaction and only a transient humoral reaction 2 months after implantation. This first assay in human surgery gave a good functional result, and an immunological response was no longer observed 5 months after grafting.

Animals↗
PubMed1983

In-vitro responses to ascorbate and manganese in fibroblasts from a patient with prolidase deficiency and iminodipeptiduria: cell growth, prolidase activity and collagen metabolism.

After successful ascorbate and manganese treatment of a female patient with prolidase deficiency and iminodipeptiduria, we attempted to explain the mechanism of action of these drugs in vitro, using them preferentially on skin fibroblasts. Since in vivo, ascorbate and manganese seemed to be responsible for both biochemical and clinical improvement, they were also expected to activate prolidase activity in vitro. Cell growth and prolidase activity were accordingly observed in fibroblast cultures supplemented with these compounds. It seemed that only ascorbate accounted for the successful in vivo response. To understand the mechanism involved, we studied collagen metabolism and found a decreased proline pool, a massive increase of rapidly degraded collagen and moderate enhancement of type III collagen and type I trimer in the patient's fibroblasts. We believe that ascorbate allowed the prolidase-deficient cells to maintain a normal collagen pool by increasing collagen synthesis. Both the massive increase in cell growth in response to ascorbate and the bad response as regards the quality of the collagen produced confirm the secondary nature of this mechanism. However, the relationship between accelerated collagen catabolism and prolidase deficiency remains unclear.

Adult↗
PubMed1983

The reconstitution of living skin.

A living-skin equivalent useful as a skin replacement and as a model system for basic studies has been fabricated and tested extensively. It consists of two components: (1) a dermal equivalent made up of fibroblasts in a collagen matrix that is contracted and modified by the resident cells, and (2) an epidermis that develops from keratinocytes "plated" on the dermal equivalent. A multilayered keratinizing epidermis with desmosomes, tonofilaments, and hemidesmosomes forms. Basement lamella formation occurs within 2 weeks in vitro when rat cells are used. With human cells, crypt or pseudofollicular morphogenesis is observed in vitro within 3 weeks after plating cells on the dermal equivalent. Autografts and isografts of rat-skin equivalents made with cultured cells from biopsies are rapidly vascularized, block wound contraction, and persist essentially for the lifespan of the host. Seven to 9 days after grafting, donor cells become activated biosynthetically and mitotically. By 1 year, the dermal population decreases to a normal level and the matrix has been extensively remodeled. The grafts remain free of hair and sebaceous glands. Grafts to rats have been in place for over 2 years. Now, allografts of dermal equivalents have been made across a major histocompatibility barrier and are not rejected. The persistence of cellular elements of the grafts is monitored by use of a genetic marker. Challenge of the allograft with a second skin-equivalent graft after 1 month does not result in rejection of the original graft or of the second skin-equivalent graft. We propose that allografts of tissue equivalents are tolerated because cells with class II antigens are selected against during in vitro cultivation and are excluded from the graft. Thus the fabrication of skin-equivalent tissues or of other equivalent tissues with parenchymal cells that do not bear class II antigens may render transplants of such tissues immunologically acceptable despite the presence of allogeneic cells. The capacity to graft across major histocompatibility barriers using living tissue equivalents may have important clinical significance.

Animals↗