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Biomedical subjects

L Meunier

Publications and source records attributed to L Meunier.

At least 73 records · Page 4Linked to original sources
PubMed1995

[Primary cutaneous nocardia asteroides nocardiosis in an immunocompromised patient].

INTRODUCTION: Nocardiasis is caused by a germ belonging to the Actinomycetales order. Skin disease usually occurs as a secondary localization of a pulmonary infection in an immunocompromised patient. Purely cutaneous lesions usually occur in immunocompetent subjects. CASE REPORT: We observed primary cutaneous nocardiasis due to N. asteroides with a cold abscess in a patient with a pemphigoid given immunodepression treatment. DISCUSSION: Primary cutaneous nocardiasis can occur by direct contamination of a skin wound. In our patient with a pemphigoid given immunodepression treatment, the erosion of a pemphigoid bulla and general corticosteroid treatment favoured the localized infection. Cure could not be obtained until after 7 months treatment. This long course can be explained by the need to continue high-dose general corticosteroids to control the pemphigoid.

Aged↗
PubMed1994

CD11b+ macrophages that infiltrate human epidermis after in vivo ultraviolet exposure potently produce IL-10 and represent the major secretory source of epidermal IL-10 protein.

Because activated human macrophages can be potent sources of IL-10, and because immunosuppressive tolerance-inducing macrophages populate the skin after UV exposure, we determined whether IL-10 is induced after UV exposure of human skin and whether it is related to the immigrating macrophages. Keratomes were obtained from control skin or from skin obtained 72 h after a single exposure to four minimal erythemal doses of UVB. Quantitative reverse-transcriptase PCR on total RNA extracted immediately from skin keratomes showed that IL-10 mRNA was elevated in UV-exposed skin. Epidermal cell suspensions from non-UV-exposed keratomes (C-EC) and UV-exposed keratomes (UV-EC) were fractionated by sequential immunobead selection. IL-10 mRNA was reproducibly 200- to 400-fold higher in CD11b+ UV-EC (macrophages) relative to CD11b- UV-EC (keratinocytes). IL-10 mRNA was not detected in C-EC that contained the CD1a+ population (Langerhans cells) nor in CD1a- C-EC keratinocytes from normal skin. As determined by ELISA, CD11b+ UV-EC IL-10 cell-associated protein was fivefold higher than that of CD11b- UV-EC; this was confirmed by flow cytometric visualization of IL-10 protein in permeabilized cells. CD11b+ UV-EC macrophages secreted IL-10 protein into the supernatant at a level of 333 +/- 51 pg/10(6) cells, whereas UV-EC keratinocytes did not secrete detectable levels of IL-10 (n = 3), although UV did induce low levels of IL-10 mRNA and cell-associated protein in keratinocytes. Therefore, although human keratinocytes accumulate intracellular IL-10 after in vivo UV exposure, the most potent production and secretion of IL-10 in the epidermis seems to be that of UV-induced macrophages. Skin-infiltrating macrophage secretion of such a potent immunoregulatory cytokine may account for the delayed immunosuppressive environment of sunburned skin and the altered APC activity of the infiltrating macrophages.

Adult↗
PubMed1994

Retinoic acid upregulates human Langerhans cell antigen presentation and surface expression of HLA-DR and CD11c, a beta 2 integrin critically involved in T-cell activation.

Immunomodulatory effects of retinoids may be part of their anti-carcinogenic and anti-inflammatory properties. We studied the in vivo effects of retinoic acid (RA) on antigen-presenting activity of human epidermal Langerhans cells and on accessory cell activity of keratinocytes. Two skin sites from each volunteer were treated in vivo with 0.1% RA or vehicle, respectively, once a day for 4 d. RA-treated epidermal cell (RA-EC) alloantigen presentation to CD4+ T cells in each volunteer tested was consistently greater than that induced by vehicle EC. However, this increased antigen-presenting activity did not lead to autoreactive CD4+ T-lymphocyte proliferation. Elevated unfractionated epidermal antigen-presenting activity of RA-EC was not due to increased keratinocyte major histocompatibility complex (MHC) or intercellular adhesion molecule expression or to other keratinocyte accessory signaling, because incubation of CD1a-fluoroscence-activated cell sorter (FACS)-purified RA-EC inhibited alloantigen presentation, presumably through increased keratinocyte transforming growth factor-beta. By contrast, Langerhans cell function was upregulated; FACS-purified CD1a+ Langerhans cells derived from RA-EC displayed a markedly increased ability, relative to Langerhans cells from vehicle EC, to present alloantigen to T cells. Triple color flow-cytometric analysis of RA-EC and vehicle EC suspensions revealed that RA treatment did not modify the number of DR+ and CD1a+DR+EC, but did result in statistically significant increases in Langerhans cells expression of HLA-DR, CD11c, and CD1c. Another novel finding was that HLA-DR-dependent Langerhans cells antigen-presenting activity in both normal and RA-treated skin was completely blocked by anti-CD11c antibody. Thus, retinoid upregulation of antigen-presenting activity may be due to upregulation of Langerhans cell CD11c, as well as class II MHC. Upregulation of cutaneous immune responsiveness in human skin without autoreactivity has not (to our knowledge) been reported previously, and the Langerhans cell phenotypic and functional state achieved is distinct from previously reported states of Langerhans cell activation.

Antigen Presentation↗
PubMed1994

Acquired progressive lymphangioma.

Acquired progressive lymphangioma (APL) is a rare, benign proliferation of lymphatic capillary origin, which is characterized histologically by dermal vascular channels and a 'dissection of collagen' appearance. We describe a 30-year-old patient with an extensive, refractory APL on the right breast, which slowly developed over a period of 23 years. Pathologists and dermatologists should be aware of this entity, as early surgical treatment may be totally curative when the lesion is limited in size.

Breast Neoplasms↗
PubMed1994

[Scleroderma of the shoulders after treatment with combined bleomycin and radiotherapy].

INTRODUCTION: There are many causes of scleroderma. We observed a case of scleroderma involving the shoulder and neck area after combined bleomycin and radiotherapy. CASE REPORT: After six cycles of a CHOP-bleo protocol followed by radiotherapy for lymph node lymphoma, a female patient presented scleroderma involving the shoulders and neck area. Total bleomycin dose was 252 mg. DISCUSSION: Among the imputable factors, particularly extrinsic factors, in a series of 33 cases of different chemotherapy protocols published by Peters et al. in 1988, we retained the bleomycin radiotherapy administration sequence as the cause of this complication. Given after bleomycin, radiotherapy could increase the risk of scleroderma.

Adult↗
PubMed1993

[Rosacea].

Rosacea is a frequent disease which occurs mostly in women with dry skin and much more rarely in men with greasy skin. In women, rosacea is heralded, around the age of 20 years, by intermittent facial erythema, and this is followed by the gradual development of permanent erythema (erythrosis) with telangiectasia (couperose) and later on, around the age of 40, very unsightly papulo-pustules (papular rosacea, improperly called acne rosacea). In men, these successive stages are less frequent, but progressive dilatation of the nose due to sebaceous gland overgrowth may occur (rhinophyma). Rosacea is caused by vascular abnormalities not completely determined, and also, at the papulo-pustural stage, by a small parasite called Demodex folliculorum. Treatment rests on hygienic and dietary rules and vasoconstrictor drugs at the erythema stage, then on fine electrocoagulation or pulsed dye laser to suppress couperose and on the prescription of long-term low-dose tetracycline, sometimes preceded by a 2-month course of metronidazole to remove the papulo-pustules. Rhinophyma is treated by surgery. The results obtained are remarkable, at least on couperose, papulo-pustules and rhinophyma.

Adult↗
PubMed1993

Heterogeneous populations of class II MHC+ cells in human dermal cell suspensions. Identification of a small subset responsible for potent dermal antigen-presenting cell activity with features analogous to Langerhans cells.

Little is known regarding the identification, classification, and function of class II MHC+ dendritic cells in the perivasculature of human connective tissues, such as the dermis. We developed a method for preparing papillary dermal cell suspensions from human keratome strips. Among the class II MHC+ populations of the dermis identified using triple color flow cytometry, cells of monocyte/macrophage lineage (CD45+ CD1- CD11b+ CD11clo-mid CD32+ CD36+ or - CD11a-) and mesenchymal cells of non-bone marrow origin (CD45-) were identified and characterized. Another distinct class II MHC+ subset was identified, which expressed a number of features analogous to epidermal Langerhans cells (LC) and other dendritic APC. These were a numerically minor population comprising only 2.7% +/- 1% (n = 7) of dermal cells. Like LC, they express HLA-DR, CD45, CD1a (albeit at a lower level of expression), CD1c, and CD32 and lack constitutive CD11a or ICAM-1. In contrast to LC, this dermal CD1a+CD1c+ subset expresses CD1b, CD11b, a higher level of CD11c, and intracytoplasmic factor XIIIa. Alloantigen presentation by unfractionated dermal cells was reduced by prior removal of this CD1b+ subset to the same degree achieved by removal of the entire DR+ population (20% of dermal cells), indicating that this was the critical DR+ subset. Cocultures of CD4+ T lymphocytes with cells sorted by flow cytometry into CD1c+DR+, CD1c-DR+ and DR- dermal cell subsets positively identified the CD1c+DR+ population as the most potent of potential APC subsets in human dermis. Thus, in distinction to other dermal macrophage and mesenchymal subsets with elongate morphology, the CD1aloCD1b,c+CD11c(hi)CD11b+CD32+DR+ population in human dermis is highly analogous to cells of LC/dendritic APC lineage in its phenotype and in its exclusive ability to potently present Ag to T lymphocytes. These studies identify and characterize the APC subset most potent in inducing activation of T cells initially entering the perivasculature of human dermis to be of LC/dendritic APC, and not tissue macrophage, lineage.

Adult↗
PubMed1992

Treatment of psoriasis with a 311-nm UVB lamp.

In a left-right comparative study, the Philips TL-01 sunlamp, a new UVB fluorescent lamp, was evaluated in 15 patients with symmetrical psoriasis. One half of the body was treated in a cabin containing TL-01 lamps, and the other half in a cabin containing TL-12 lamps. The patients were treated three times/week, and the study was conducted in a randomized, double-blind fashion. The percentage response of psoriatic lesions was determined on the tenth and twentieth exposures. The therapeutic effect of the TL-01 lamps was superior to that of the TL-12 lamps, and treatment was better tolerated, particularly with regard to episodes of burning. This new lamp appears to provide more effective and safer phototherapy for psoriasis.

Adult↗
PubMed1992

[Narrow-band UVB phototherapy (Philips TL01 lamps) in psoriasis].

The authors report the results of an open study conducted on 53 patients with psoriasis treated by narrow-band UVB phototherapy, using Philips' TL01 lamp. With a simple procedure which did not require MED determination this treatment gave satisfactory results in 92 p. 100 of the cases, with mild burns in only 9 p. 100. The morphological type of psoriasis (patchy, guttate or nummular) had no influence on the therapeutic result, but the degree of infiltration of the lesions and their location on the lower limbs proved to be a factor of relative resistance. In most patients the results were obtained in 20 sessions with a mean cumulative dose of 20.19 +/- 2.7 J/cm2. Some patients had an additional treatment of 6 sessions. The results obtained with Philips' TL01 lamp were as satisfactory as those obtained with the conventional UVB lamps, but the TL01 lamp seemed to be easier to handle and better tolerated, which gives them some advantages over the latter.

Adolescent↗
PubMed1991

[Light-induced aging of the skin].

Ageing of the skin results from the synergistic effects of intrinsic, genetically determined factors and extrinsic factors the most important of which is chronic exposure to sunlight. The cumulative effects of ultraviolet radiations are responsible for specific dermo-epidermal alterations (actinodermatitis) with its two main manifestations: actinic elastosis characterized by accumulation of dystrophic fibres in the dermis, and lesions of senile keratosis which may become carcinomas. The so-called "premature ageing of the skin" can be alleviated by cosmetic treatments, photoprotective measures and vitamin A derivatives; regular applications of retinoic acid (vitamin A acid, tretinoin) can result in partial regression of actinodermatitis.

Epidermis↗
PubMed1991

Technique for quantification of LTB4-induced changes in peripheral granulocyte counts in vivo in the rabbit.

A method to quantify leukotriene B4-(LTB4)-induced changes in peripheral granulocyte counts in the rabbit is described. Rabbits were surgically prepared with vascular access ports cannulating the right external jugular vein. This preparation made possible rapid, accurate, and repeated sampling of venous blood. Intravenous infusion of LTB4 (0.5-2 micrograms/mL) into the left marginal ear vein was found reproducibly to cause an initial, rapid (1-5 min) leukopenia (64%-100% reduction) followed by an extended (20-30 min) leukocytosis (121%-178% increase). Saline infusion for 30 min resulted in no changes in peripheral granulocyte number. The method described was sensitive and reproducible enough to allow evaluation of the LTB4 receptor antagonist, LY223982 (10 mg/kg, i.v.), which was shown to block both the leukopenia and the leukocytosis induced by LTB4 infusion.

Animals↗
PubMed1990

[Then physiopathology of atopic dermatitis].

Atopic dermatitis is transmitted as an autosomal dominant trait. Its expressivity is variable, and flare-ups are triggered by environmental factors such as air-borne allergens, cutaneous flora or foodstuffs. Elevation of serum IgE levels is inconstant and not specific; it is associated with a deficiency of suppressor T cell population. The epidermis contains IgE bound to the surface of Langerhans cells; this abnormality seems to be specific as it is not found in atopic or non atopic healthy subjects. The lack of beta-adrenergic response is partially explained by the hyperactivity of the cyclic AMP-degrading phosphodiesterase. Disturbances in essential fatty acid metabolism (inactivation of delta 6 desaturase) are thought to be responsible for abnormalities in the permeability of epithelial structures. The relationships between pharmacological, biochemical and immunological dysregulations are unknown.

Dermatitis, Atopic↗
PubMed1990

Specific effects of retinoic acid on the skeletal morphogenesis of the 11-day mouse embryo forelimb bud in vitro.

Using our improved method for culturing 11-day mouse forelimb buds in vitro, we have investigated the effects of a local application of all-trans-retinoic acid (RA) on growth, cartilaginous differentiation and skeletal patterning in the mammalian limb bud. Carrier implants of catgut impregnated with DMSO or various doses of RA in DMSO were inserted at the apex of the buds in the proximo-distal axis just beneath the apical ectodermal ridge. After 6 days of culture, cartilaginous skeletons were stained and explants were processed for morphological analysis and quantitative study using computerized optical image analysis. Buds treated with low doses of RA exhibited stimulated growth and chondrogenesis. Moreover, hypertrophied and fused metacarpals were seen within explants treated with the lowest dose. High doses strongly inhibited growth and skeletal morphogenesis. An intermediate dose sustained cartilaginous differentiation at the same level as low doses, but concomitantly disturbed the skeletal pattern. These results are discussed considering reported RA effects on other experimental systems including avian limb bud as an in vivo model or cell cultures as an in vitro simplified model.

Animals↗