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Biomedical subjects

M Faure

Publications and source records attributed to M Faure.

At least 127 records · Page 7Linked to original sources
PubMed1991

Reactivity of indole derivatives towards oxygenated radicals.

The reactivity of a series of indole derivatives was assessed in the following systems: (i) oxidation of the indole derivatives induced by the thermolysis of 2,2'-azobis-(2-amidinopropane) (ABAP); (ii) oxidation of cumene induced by the thermolysis of 2,2'-azobis-(2-methyl propionitrile) (AIBN); (iii) lysozyme inactivation induced by the thermolysis of ABAP and (iv) brain homogenate autoxidation. In systems (ii) to (iv), addition of the indole derivatives decreases the rate of the process. The data obtained indicate that common factors (i.e., oxidation potential and presence of N-H bonds) control the reactivity of the indole derivatives in the four systems considered. However, in the brain homogenate autoxidation, hydrophobicity is an additional factor that affects the efficiency of antioxidants, as illustrated by Q1/2 values (the concentration of additive required to decrease the autoxidation rate to one half that observed in the absence of additive) of 0.1 mM and much greater than 8 mM for 3-methylindole and tryptophan, respectively.

Animals↗
PubMed1991

Effect of additives on the inactivation of lysozyme mediated by free radicals produced in the thermolysis of 2,2'-azo-bis-(2-amidinopropane).

The inactivation of lysozyme caused by the radicals produced by thermolysis of 2,2'-azo-bis-2-amidinopropane can be prevented by the addition of different compounds that can react with the damaging free radicals. Compounds of high reactivity (propyl gallate, Trolox, cysteine, albumin, ascorbate, and NADH) afford almost total protection until their consumption, resulting in well-defined induction times. The number of radicals trapped by each additive molecule consumed ranges from 3 (propyl gallate) to 0.12 (cysteine). This last value is indicative of chain oxidation of the inhibitor. Uric acid is able to trap nearly 2.2 radicals per added molecule, but even at large (200 microM) concentrations, a residual inactivation of the enzyme is observed, which may be caused by urate-derived radicals. Compounds of lower reactivity (tryptophan, Tempol, hydroquinone, desferrioxamine, diethylhydroxylamine, methionine, histidine, NAD+ and tyrosine) only partially decrease the lysozyme inactivation rates. For these compounds, we calculated the concentration necessary to reduce the enzyme inactivation rate to one half of that observed in the absence of additives. These concentrations range from 9 microM (tryptophan and Tempol) to 5 mM (NAD+).

Amidines↗
PubMed1990

[Acute lupus erythematosus disseminatus in adults: clinical aspects & course].

Acute systemic lupus erythematosus (SLE) is characterized by a variety of manifestations and by the almost constant presence of anti-nuclear antibodies. In order to distinguish it from other systemic diseases, eleven diagnostic criteria have been laid down, four of which at least must be present. In 50 p. 100 of the cases the disease is revealed by a non-destructive inflammatory polyarthritis which is highly suggestive when associated with a "butterfly" facial erythema. The main prognostic criteria are renal lesions and their histological type. Nervous system involvement seems to be less frequent and less severe nowadays, but it may leave sequelae. Pleuropericarditis and vascular thrombosis are commonly part of the clinical set up. Antinuclear antibodies are detected by immunofluorescence in more than 95 p. 100 of the patients, but they are not specific to SLE. Their absence in the initial phase of the disease may throw doubts on the diagnosis. Antibodies to DNA and Sm are more specific but inconstant. SLE is a chronic disease with intermittent flare-ups: 30 p. 100 of the patients may hope for a prolonged complete remission. At present, the survival rate at 10 and 20 years is higher than 80 p. 100 and 70 p. 100 respectively at the cost of a very close supervision but also of iatrogenic complications in increasing numbers.

Acute Disease↗
PubMed1990

Action of staphylococcal exfoliative toxins on epidermal cell cultures and organotypic skin.

In the staphylococcal scalded skin syndrome, spontaneous intraepithelial cleavages are due to the exfoliative toxins A or B (ETA or ETB). Until now, these toxins have been studied either on epidermis or on organotypic skin cultures. In the present study, we compare the effects of these toxins on human keratinocyte cell cultures to those on human and mouse organotypic skin cultures. With concentrations of ETA or ETB of 1 mg/ml for 3 hours, spontaneous intraepithelial cleavages were noted in both cell and organotypic cultures. Keratinocyte cell cultures were as sensitive as organotypic skin cultures to these toxins. Since keratohyaline granules may represent a possible binding site for ETA or ETB, we tried to correlate the expression of keratohyaline granules with the appearance of intraepithelial clefts due to the toxins. However, when cultured in liquid medium, epithelia were not differentiated enough to allow the detection of the binding site of ETA-ETB.

Animals↗
PubMed1990

Cultured epithelia from junctional epidermolysis bullosa letalis keratinocytes express the main phenotypic characteristics of the disease.

Keratinocytes from a 1-week-old male infant with junctional epidermolysis bullosa letalis (JEBL) were grown in vitro and then grafted as multi-layered epithelia onto nude mice, to investigate whether the defect in the dermo-epidermal cohesiveness in the disease is of epidermal and not mesodermal origin. In culture, there was a birefringent ring of cells at the edges of the keratinocyte colonies and in places some cells looked as though they had been ejected from the periphery of the colony. At confluence, the multi-layered epithelia were easily detached from the culture flasks using only mechanical agitation. On microscopy the fully-differentiated epithelium on days 21, 30 and 40 after grafting sometimes showed blistering at the dermal-epidermal junction. No labelling was noted using a GB3 monoclonal antibody, that reacts with normal human keratinocytes in culture and with the dermo-epidermal basement membrane zone in normal skin. This indicates that the defect of JEBL may be reproduced in culture and also after grafting the cultured epithelial onto a wound without an epidermis. This suggests a possible role for the junctional structure recognized by GB3 in dermo-epidermal cohesiveness.

Animals↗
PubMed1990

The cyclic nucleotide phosphodiesterase gene of Dictyostelium discoideum contains three promoters specific for growth, aggregation, and late development.

The cyclic nucleotide phosphodiesterase (phosphodiesterase) plays essential roles throughout the development of Dictyostelium discoideum. It is crucial to cellular aggregation and to postaggregation morphogenesis. The phosphodiesterase gene is transcribed into three mRNAs, containing the same coding sequence connected to different 5' untranslated sequences, that accumulate at different times during the life cycle. A 1.9-kilobase (kb) mRNA is specific for growth, a 2.4-kb mRNA is specific for aggregation, and a 2.2-kb mRNA is specific for late development and is only expressed in prestalk cells. Hybridization of RNA isolated from cells at various stages of development with different upstream regions of the gene indicated separate promoters for each of the three mRNAs. The existence of specific promoters was confirmed by fusing the three putative promoter regions to the chloramphenicol acetyltransferase reporter gene, and the analysis of transformants containing these constructs. The three promoters are scattered within a 4.1-kilobase pair (kbp) region upstream of the initiation codon. The late promoter is proximal to the coding sequence, the growth-specific promoter has an initiation site that is 1.9 kbp upstream of the ATG codon, and the aggregation-specific promoter has an initiation site 3 kbp upstream.

Amino Acid Sequence↗
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↗