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Biomedical subjects

M Faure

Publications and source records attributed to M Faure.

At least 145 records · Page 8Linked to original sources
PubMed1990

Effects of cyclosporin A on cultured human epidermal keratinocytes. Growth and 5-bromo-2'-deoxyuridine incorporation.

We have studied the in vitro effect of CsA at various doses (0.5, 1, 5, 10 micrograms/ml) on the growth and 5-bromo-2'-deoxyuridine (BrdU) incorporation by cultured normal human epidermal keratinocytes (EK). CsA was found to reduce the growth of EK at all doses used after 24, 48 and 72 h in culture, but the difference with appropriate controls became statistically significant for the dose of 10 micrograms/ml after a 48- and 72-h culture. On the other hand, CsA-treated EK comprised a reduced fraction of BrdU + (S-phase) cells, the difference being statistically significant for the dose of 10 micrograms/ml at 24, 48 and 72 h. Ultrastructural examination of CsA-treated EK, despite the presence of cytoplasmic vacuoles also observed in control EK did not show signs of severe cytoplasmic or nuclear damage. These results confirm the antiproliferative effect of CsA on cultured EK and suggest that at the concentration used, CsA acts through a cytostatic rather than a cytotoxic mechanism, most likely by blocking EK in an early phase (G0/G1) of the cell cycle.

Cell Count↗
PubMed1990

[Clinical application of grafts of cultured epidermis in burn patients. Apropos of 16 patients].

The authors report a series of 16 patients with extensive burns partially treated by epidermal culture between May 1985 and July 1988. This series consisted of 9 males and 7 females between the ages of 6 and 88 years (mean age: 34 years). The mean surface area of the burns was 66% (range: 30% to 92%). The technique of epidermis culture used was derived from that developed by Green and Rheinwald. A fragment of full-thickness skin taken from the patient was subjected to the action of trypsin. The keratinocytes were cultured on nutrient layers of 3T3 cells. After 10 days, the secondary cultures corresponded to stratified squamous epithelium with a differentiation similar to that of normal human epithelium. This cultured epithelium was used for autografts as well as allografts. Three deaths were related to septic or metabolic complications of the burn. The take rate of the initial graft was greater than 50% in 9 patients. In 3 patients the graft take rate was less than 50% and in 4 patients it was nil. The long-term evaluation of 12 patients revealed partial lysis of the grafts in 3 patients, a stable result in 6 patients and a healed surface greater than the grafted surface in three cases. The best results were obtained with autografts. The initial evaluation of taking of the graft is difficult, as the fine and shiny texture of the grafts is sometimes difficult to distinguish from non-covered zones. The good tolerance of cultured epidermis allografts is due to the fact that they are devoid of Langerhans cells. Although controversial, the reality of the taking of these allografts opens the way to establishing epidermis culture banks.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

Molecular characterization of a Dictyostelium discoideum gene encoding a multifunctional enzyme of the pyrimidine pathway.

We have isolated and characterized a Dictyostelium discoideum gene (PYR1-3) encoding a multifunctional protein that carries the three first enzymatic activities of the de novo pyrimidine biosynthetic pathway. The PYR1-3 gene is adjacent to another gene of the pyrimidine biosynthetic pathway (PYR4); the two genes are separated by a 1.5-kb non-coding sequence and transcribed divergently. The PYR1-3 gene is transcribed to form a 7.5-kb polyadenylated mRNA. As with the other genes of the pyrimidine biosynthetic pathway, the PYR1-3 mRNA level is high during growth and decreases sharply during development. We have determined the nucleotide sequence of 63% of the coding region of the PYR1-3 gene. We have identified the activities of the protein encoded by the D. discoideum PYR1-3 gene by comparison of amino acid sequences with the products of genes of known function. The PYR1-3 gene contains four distinct regions that probably correspond to four domains in the protein. From the NH2 extremity to the COOH extremity, these domains are: glutamine amidotransferase, carbamoylphosphate synthetase, dihydroorotase and aspartate transcarbamylase. This organization is identical to the one found in the rudimentary gene of Drosophila. The evolutionary implications of this finding are discussed.

Amino Acid Sequence↗
PubMed1989

Cultured keratinocyte grafts are recognized, but not rejected by CD8+ T cells in vivo.

It has been shown in the mouse that cultured keratinocyte allografts [fully major histocompatibility complex (MHC) mismatched] survive for at least 100 days without evidence of rejection. In an attempt to analyze the immune mechanisms underlying this phenomenon we have investigated the induction of tolerance to such grafts. Primary cultures of BALB/c keratinocytes were prepared using irradiated 3T3 feeder cells, and the cultured cell sheets were grafted, using a silicone transplantation chamber, onto CBA recipients. After the cultured grafts had been in place for 4-6 weeks full-thickness tail skin from BALB/c donors was grafted onto the dorsal flank opposite the cultured graft. The median graft survival time of these full-thickness allografts was 15.5 days compared to 13 days in the control group. These data show that in the absence of Langerhans cells and MHC class II expression, keratinocytes expressing class I and minor histocompatibility antigens induce a prolonged survival of full-thickness skin allografts. The results from experiments in which T cell subsets were depleted in vivo suggest that CD8+ cells (a) recognize the class I alloantigens of the cultured graft, (b) do not reject the cultured graft and (c) do not progress further in their maturation pathway. We propose that these CD8+ T cells might have been partially primed by receiving only the first signal of activation and that they may be equivalent to "poised" cytotoxic T cells. These CD8+ cells can reject non cultured full-thickness skin grafts, and do so more effectively after removing CD4+ cells.

Animals↗
PubMed1989

Rescue of a Dictyostelium discoideum mutant defective in cyclic nucleotide phosphodiesterase.

One of the developmentally induced gene products that is essential for chemotaxis of Dictyostelium amoebae is a cyclic nucleotide phosphodiesterase. The enzyme can be secreted or exist in a membrane bound form. This enzyme is missing in the mutant HPX235 which, as a consequence, does not aggregate unless exogenous cAMP phosphodiesterase is supplied. We have introduced multiple copies of the cloned phosphodiesterase gene into mutant amoebae and restored aggregation. The formation of anatomically correct fruiting bodies, which does not occur when exogenous enzyme is added, is also restored by transformation with the gene. The construct that we have used gives rise only to secreted phosphodiesterase and therefore the membrane bound form of the enzyme is not absolutely required for normal aggregation and morphogenesis.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1989

Re-expression of disease-characteristic features of non-bullous congenital ichthyosiform erythroderma (CIE) after grafting of the pathological keratinocyte cultures to athymic mice.

Epidermal keratinocytes separated from skin lesions of non-bullous congenital ichthyosiform erythroderma were investigated in an attempt at experimental reproduction of this keratinization disorder. In vitro studies on growth and differentiation of pathological keratinocytes isolated from the influence of the host's dermal and humoral components were performed using the immersed epidermal cell culture technique. Ten to 25-day-old confluent and stratified cultures were examined by means of photonic and electron microscopy, and stained with various differentiation markers for indirect immunofluorescence studies. The cultured epidermis showed low-grade differentiation and no clear-cut evenly distributed signs of the original disease. Grafting on congenitally athymic nude mice allowed further differentiation of the epidermal sheets and re-expression of the histologic and ultrastructural features of non-bullous congenital ichthyosiform erythroderma. Thus, the purely epidermal origin of this particular form of autosomal recessive ichthyosis could be confirmed. Large amounts of pathological keratinocytes generated from small skin biopsies may be used for experimental purposes after grafting on several athymic animals.

Animals↗
PubMed1989

The cyclic nucleotide phosphodiesterase gene of Dictyostelium discoideum utilizes alternate promoters and splicing for the synthesis of multiple mRNAs.

The cyclic nucleotide phosphodiesterase (phosphodiesterase) gene plays essential roles in the development of Dictyostelium discoideum during cellular aggregation and postaggregation morphogenesis. Genomic clones spanning the gene were isolated and used to determine the sequence and structure of the phosphodiesterase gene. We found an unusually complex organization for a gene of D. discoideum. Two transcripts of 2.4 and 1.9 kilobases (kb) were synthesized from start sites separated by 1.1 kb. A developmentally regulated promoter was utilized for the 2.4-kb mRNA, and a constitutive promoter regulated synthesis of the 1.9-kb transcript. The gene was found to be divided into four exons that are alternately spliced to give rise to the two mRNAs. The precursor of the 2.4-kb mRNA contained a 2.3-kb intron, whereas the precursor of the constitutive transcript was synthesized with a 1.7-kb intron. The two transcripts contained identical protein-coding regions and 400-nucleotide 3' untranslated sequences. The 2.4-kb developmentally regulated mRNA was distinguished by a long 5' untranslated leader of 666 nucleotides. The complex structure of the gene may allow multiple levels of control of the expression of the phosphodiesterase during development.

Base Sequence↗
PubMed1989

Nonimmunosuppressive ciclosporin H inhibits the growth and DNA synthesis of cultured normal human epidermal keratinocytes.

Ciclosporin H (CsH) is an epimer (11-D-N-methyl-L-valine) of ciclosporin A (CsA) devoid of immunosuppressive properties. The known antiproliferative effect of CsA on epidermal keratinocytes (EK) grown in vitro prompted us to study the effect of CsH (at the doses of 0.5, 1, 3.5 and 5 micrograms/ml) on the growth and DNA synthesis (5-bromo-2'-deoxyuridine incorporation). CsH was observed to reduce both the number and DNA synthesis of EK in a statistically significant manner at the dosage of 5 micrograms/ml after 24, 48 and 72 h in culture. These results show that the immunosuppressive properties of the ciclosporins (Cs) are dissociated from the antiproliferative ones on EK and highlight the interest of further in vivo studies that may lead to therapeutic applications of Cs in hyperproliferative epidermal diseases requiring no immunosuppression.

Bromodeoxyuridine↗
PubMed1989

[Use of human epithelial cultures in mucogingival surgery].

A clinical technique utilizing autologous cultured epithelial cells in vestibule deepening operations is described. Epithelial cells from oral mucosa were grown in tissue culture on a feeder layer, released from their flasks and placed with the basal side up on the recipient beds. The cultured cells induced rapid healing of the wound, which was free of pain and contractions. The greatest advantage of this technique is that there is no size limitation on wounds that can be covered by cultured epithelial cells.

Adolescent↗
PubMed1989

[Chondrosarcoma of the soft parts of the thoracic wall. Apropos of a case after surgery and irradiation of breast adenocarcinoma].

We are reporting here a case of chondrosarcoma of the soft tissues of the thoracic wall. As far as we can tell it is the first case published in the world. The tumour appeared 13 years after radical mastectomy and radiotherapy for an adenocarcinoma of the breast. The tumor was greyish-white in appearance and hard, but friable and haemorrhagic. Clinically and biologically it looked like an inflammatory mass. This disappeared when the tumour had been removed but recurred 6 days post-operatively when nodules showing that it had permeated the tissues appeared. Histological and immunohistochemical examination confirmed the diagnosis. We discuss the clinical and histological aspects of the case and state what we found in the literature about other sarcomas that have followed adenocarcinomata of the breast that had been irradiated and operated on. The role of radiotherapy in bringing about this tumour is discussed, including the relationship between the site of the tumour and the dose and field of irradiation. The prognosis is particularly bad in this type of sarcoma which was induced by irradiation.

Adenocarcinoma↗
PubMed1988

The cyclic nucleotide phosphodiesterase of Dictyostelium discoideum: the structure of the gene and its regulation and role in development.

The cyclic nucleotide phosphodiesterase (phosphodiesterase) of Dictyostelium discoideum plays an essential role in development by hydrolyzing the cAMP used as a chemoattractant by aggregating cells. We have studied the biochemistry of the phosphodiesterase and a functionally related protein, the phosphodiesterase inhibitor protein, and have cloned the cognate genes. A 1.8-kb and a 2.2-kb mRNA are transcribed from the single-phosphodiesterase gene. The 2.2-kb mRNA comprises the majority of the phosphodiesterase mRNA found in differentiating cells and is transcribed only during development from a promoter at least 2.5 kb upstream of the translational start site. The 1.8-kb phosphodiesterase mRNA is detected at all stages of growth and development, is present at lower levels than the developmentally induced mRNA, and is transcribed from a site proximal to the protein-coding region. The phosphodiesterase gene contains a minimum of three exons, and a 2.3-kb intron, the longest yet reported for this organism. We have shown that the pdsA gene and four fgd genes affect the accumulation of the phosphodiesterase mRNAs, and we believe that these loci represent a significant portion of the genes regulating expression of the phosphodiesterase. The phosphodiesterase gene was introduced into cells by transformation and used as a tool to explore the effects of cAMP on the terminal stages of development. In cells expressing high levels of phosphodiesterase activity, final morphogenesis cannot be completed, and differentiated spore and stalk cells do not form. We interpret these results to support the hypothesis that cAMP plays an essential role in organizing cell movements in late development as well as in controlling the aggregation of cells in the initial phase of the developmental program.

3',5'-Cyclic-AMP Phosphodiesterases↗