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Biomedical subjects

L Meunier

Publications and source records attributed to L Meunier.

At least 37 records · Page 2Linked to original sources
PubMed2001

Ultraviolet AI exposure of human skin results in Langerhans cell depletion and reduction of epidermal antigen-presenting cell function: partial protection by a broad-spectrum sunscreen.

BACKGROUND: Ultraviolet (UV) B-induced effects on the skin immune system have been extensively investigated, but little is known regarding the immunological changes induced by UVA exposure of human skin. Recent data assessing the protection afforded by sunscreens against photoimmunosuppression stress the need for broad-spectrum sunscreens with an adequate UVA protection. OBJECTIVES: The purpose of this study was first to determine the changes observed in epidermal Langerhans cells (ELC) density and epidermal antigen-presenting cell (APC) activity after exposure of human skin to UVAI (340-400 nm) radiation, and secondly to assess the immune protection afforded in vivo by a sunscreen formulation containing a long wavelength UVA filter with a low UVA protection factor (UVA-PF = 3). METHODS: Epidermal cell (EC) suspensions were prepared from skin biopsies 3 days after exposure to a single dose of UVAI (either 30 or 60 J cm(-2)). RESULTS: Flow-cytometric analysis of EC suspensions revealed that exposure to 60 J cm(-2) UVAI resulted in a decreased number of ELC without infiltration of CD36+ DR+ CD1a- antigen-presenting macrophages into the epidermis, and a significant reduction of HLA-DR expression on viable ELC. In vivo exposure to both 30 and 60 J cm(-2) resulted in a decreased allogeneic CD4+ T-cell proliferation induced by UVAI-irradiated ECs. The sunscreen application partially prevented (57 +/- 9%) the decrease in epidermal allogeneic APC activity induced by 60 J cm(-2) UVAI. CONCLUSIONS: In vivo UVAI exposure of human skin results in a decreased number of ELC and in a downregulation of epidermal APC activity. This last effect is partially prevented by prior application of a sunscreen with a low UVAI-PF value. These results indicate that increasing the absorption of UV filters for long UVA wavelengths may lead to an improved immune protection.

Adult↗
PubMed2001

Phenotypic characterization of human CD4+ regulatory T cells obtained from cutaneous dinitrochlorobenzene-induced delayed type hypersensitivity reactions.

In this study, we describe the generation and characterization of cloned human CD4+ T lymphocyte populations that have infiltrated into cutaneous, 2,4-dinitrochlorobenzene-induced delayed type hypersensitivity reactions in healthy human subjects. It is shown that, in addition to T helper type 1 clones, elevated numbers of regulatory T clones, producing high levels of interleukin-10 and interleukin-5, but no measurable interleukin-4, were isolated from delayed type hypersensitivity reactions in four of six donors. A subsequent challenge with 2,4-dinitrochlorobenzene of two donors from whom only few interleukin-10-producing T cell clones had been generated after primary challenge, resulted in a decrease in the frequency of T helper type 1 clones and a strong increase in the number of interleukin-10-producing T helper type 2 and regulatory T clones. Culture supernatants from the latter cells, activated with anti-CD3 and anti-CD28 monoclonal antibody, inhibited alloantigen-mediated T cell proliferation which was, partly dependent on interleukin-10, and independent of transforming growth factor-beta. In addition, dendritic cells generated in vitro in the presence of these culture supernatants were impaired in their ability to induce alloantigen-induced proliferative responses. Differential expression of transcripts for the T1/ST2 molecule enabled a phenotypic distinction between resting regulatory T cells and T helper type 2 cells, but not between regulatory T cells and T helper type 1 cells. This experimental model provides a useful tool to isolate human inflammatory and anti-inflammatory T cell subpopulations and, furthermore, enables the study of the kinetics of their appearance into delayed type hypersensitivity reactions.

CD4-Positive T-Lymphocytes↗
PubMed2001

Propynylated phosphodiester oligonucleotides inhibit ICAM-1 expression in A549 cells on electroporation.

Oligodeoxynucleotides (ODN) are used largely as either primers, antisense, or triplex-forming units. Phosphodiester ODN (PO-ODN), which are very rapidly degraded by exonucleases, must be protected at their ends. Even so, their life span inside cells is quite short. Phosphorothioate ODN (PS-ODN) are less sensitive to nucleases and are extensively used as antisense. Unfortunately, unlike PO-ODN, they interact with a number of molecules, including proteins, in addition to their specific nucleic acid targets. Their affinity for their target is lower than that of PO-ODN. PS-ODN containing propyne groups on C5 of pyrimidine have been shown to have a higher affinity toward their nucleic acid target. Here, we show that propynylated PO-ODN are more stable and much more efficient than their propyne-free counterparts. They are not efficient when they are used as lipoplexes, but they act as specific antisense on electroporation.

Alkynes↗
PubMed2000

Optimized synthesis of phosphorothioate oligodeoxyribonucleotides substituted with a 5'-protected thiol function and a 3'-amino group.

A new deprotection procedure enables a medium scale preparation of phosphodiester and phosphor-othioate oligonucleotides substituted with a protected thiol function at their 5'-ends and an amino group at their 3'-ends in good yield (up to 72 OD units/micromol for a 19mer phosphorothioate). Syntheses of 3'-amino-substituted oligonucleotides were carried out on a modified support. A linker containing the thioacetyl moiety was manually coupled in two steps by first adding its phosphor-amidite derivative in the presence of tetrazole followed by either oxidation or sulfurization to afford the bis-derivatized oligonucleotide bound to the support. Deprotection was achieved by treating the fully protected oligonucleotide with a mixture of 2,2'-dithiodipyridine and concentrated aqueous ammonia in the presence of phenol and methanol. This proced-ure enables (i) cleavage of the oligonucleotide from the support, releasing the oligonucleotide with a free amino group at its 3'-end, (ii) deprotection of the phosphate groups and the amino functions of the nucleic bases, as well as (iii) transformation of the 5'-terminal S -acetyl function into a dithiopyridyl group. The bis-derivatized phosphorothioate oligomer was further substituted through a two-step procedure: first, the 3'-amino group was reacted with fluorescein isothiocyanate to yield a fluoresceinylated oligo-nucleotide; the 5'-dithio-pyridyl group was then -quantitatively reduced to give a free thiol group which was then substituted by reaction with an N alpha-bromoacetyl derivative of a signal peptide containing a KDEL sequence to afford a fluoresceinylated peptide-oligonucleotide conjugate.

Amides↗
PubMed2000

Brief preconditioning ischemia alters diacylglycerol content and composition in rabbit heart.

In order to give further insight into the potential role of PKC in the beneficial effects of ischemic preconditioning, we have characterized the production of diacylglycerol, the endogenous activator of PKC, and its molecular species composition in ischemic control and preconditioned hearts. Preconditioning was induced by 1 cycle of 5 min of ischemia followed by 5 min of reperfusion. In control and preconditioned groups, hearts were harvested under deep anesthesia at baseline (preischemia) and at 2, 5 and 10 min into the sustained coronary artery occlusion, i.e., preceding myocyte death. Diacylglycerol content and fatty acid composition were analyzed by thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC), respectively. Myocardial diacylglycerol content was increased at 2 min into the sustained ischemia in the control group (481 +/- 34 vs 292 +/- 64 ng x mg(-1) at baseline; p < 0.05), but was comparable to the baseline value at 5 and 10 min. In the preconditioned group, diacylglycerol production remained unchanged throughout the 10-min test ischemia (317 +/- 17 at 2 min vs 312 +/- 38 ng x mg(-1) at baseline; p = NS). A detailed analysis of the molecular species composition at the time of 2 min revealed a reduced contribution of phosphatidylinositol to diacylglycerol production in preconditioned myocardium (global correlation coefficient 0.57 vs 0.66 in control myocardium) with a trend toward an enrichment of diacylglycerol composition with some species originating from phosphatidylcholine. Thus, our study revealed that brief preconditioning ischemia: (1) prevents the increase of diacylglycerol content in the early minutes of the sustained ischemia, and (2) emphasizes the contribution of phosphatidylcholine in diacylglycerol formation to the detriment of that of phosphatidylinositol.

Animals↗
PubMed2000

[Extensive primary cutaneous mucinosis associated with refractory anemia with excess of blast].

BACKGROUND: We describe an original case of a primary cutaneous mucinosis, associated with a refractory anemia with excess of blast. CASE REPORT: A 65 year-old female consulted for erythematous-purple blush reticulated and large plaques that progressively developed on the trunk and limbs. Biopsies showed abundant dermis mucin deposits with a perivascular lymphocytic infiltrate. The epidermis was normal. Laboratory evaluation showed refractory anemia with excess of blast, associated with cytogenetic abnormalities. After two years course, the progressive aggravation of the myelodysplastic syndrome was associated with a progressive extension of the cutaneous mucinosis. DISCUSSION: This is the first report of an atypical primary diffuse and extensive cutaneous mucinosis. Primary cutaneous mucinosis may be associated with systemic diseases. To our knowledge, the association with refractory anemia with excess of blast has not been described previously. Mucine deposits may be considered as a consequence of neutrophilic dysfunction that are observed in myelodysplastic syndromes.

Aged↗
PubMed2000

Angiosarcoma of the scalp and face: failure of an interferon alpha treatment.

Angiosarcoma of the scalp and face is a rare malignant endothelial tumor arising in elderly people. Treatment is disappointing and prognosis remains poor. We report two cases of angiosarcoma of the scalp and face relapsing after classical therapy with surgery and radiotherapy and treated with interferon alpha. The tolerance was poor and the disease progressed 2 and 5 months after the onset of the treatment. When used alone, interferon alpha does not appear as an effective treatment in this kind of angiosarcoma.

Aged↗
PubMed2000

[Contact dermatitis caused by labile henna skin tattoo].

BACKGROUND: Contact dermatitis to henna are rarely reported. Most of the time, they are related to additives, especially scented oils or paraphenylene diamine. This latter substance is added to shorten the time of application and to enhance the darkness of the color. We report one case of an allergic contact dermatitis to henna skin tattoo, probably related to a paraphenylene diamine derivative. CASE REPORT: A 25-year-old woman developed an allergic contact dermatitis at the site of application of two henna skin tattoos on her right arm. She never dyed her hair and wore dark clothing without problems. Epicutaneous tests were positive for henna paste, paraphenylene diamine, N-isopropyl-N'phenylparaphenylene diamine and five chemical dyes, probably related to cross- reactions between paraphenylene diamine and these dyes. Epicutaneous test with henna powder was negative, confirming the absence of allergy to henna. Fluorescence analysis detected the presence of a primary amine in henna paste but high performance liquid chromatography analysis did not reveal the presence of paraphenylene diamine or any suspect dye. An another allergen, related compound of paraphenylene diamine, was probably present but we failed to identify it with precision. DISCUSSION: Labile henna skin tattoos are in fashion at the moment in western European countries. They can be a secrete source of paraphenylene diamine, or one of its related compounds, sensitization.

Adult↗
PubMed1999

The nuclear export signal-dependent localization of oligonucleopeptides enhances the inhibition of the protein expression from a gene transcribed in cytosol.

Upon endocytosis, most oligodeoxynucleotides (ODNs) accumulate in vesicular compartments; a tiny number of them cross the vesicle membrane, reach the cytosol and by passive diffusion enter the nucleus where they are entrapped. So far, the compartment in which an antisense ODN interacts with its mRNA target has not been precisely characterized. In an attempt to answer this question, ODN-peptides were designed with the aim of maintaining them in the cytosol. This has been achieved by a short peptide sequence called the nuclear export signal (NES). Upon microinjection, ODN-NES peptide conjugates were efficiently and rapidly exported from the nucleus to the cytosol whereas ODN-peptides containing an inactive NES were found to be located in the nucleus. The inhibitory activity of antisense ODN was tested in a system allowing the specific transcription of a luciferase reporter gene in the cytosol. Antisense propynylated ODN-NES peptide conjugates, directed against the luciferase gene, efficiently inhibited (75%) the cytosolic expression of luciferase whereas at the same concentration the peptide-free propynylated ODN or the propynylated ODN-peptides containing an inactive NES were nearly inactive.

Animals↗
PubMed1999

The expression of peripheral benzodiazepine receptors in human skin: the relationship with epidermal cell differentiation.

The peripheral benzodiazepine receptor (PBR) is a protein of mitochondrial outer membranes utilizing porphyrins as endogenous ligands. PBR is part of a heteromeric receptor complex involved in the formation of mitochondrial permeability transition pores and in the early events of apoptosis. PBR may function as an oxygen-dependent signal generator; recent data indicate that these receptors may preserve the mitochondria of haematopoietic cell lines from damage caused by oxygen radicals. To identify PBRs in human skin, we used a specific monoclonal antibody directed against the C-terminus fragment of the human receptor. PBR immunoreactivity was found in keratinocytes, Langerhans cells, hair follicles and dermal vascular endothelial cells. Interestingly, confocal microscopic examination of skin sections revealed that PBR expression was strongly upregulated in the superficial differentiated layers of the epidermis. Ultrastructurally, PBRs were distributed throughout the cytoplasm but were selectively expressed on the mitochondrial membranes of epidermal cells. The elevated level of PBRs in the spinous layer was not associated with an increased number of mitochondria nor with an increased amount of mRNA as assessed by in situ hybridization on microautoradiographed skin sections. The present work provides, for the first time, evidence of PBR immunoreactivity in human skin. This mitochondrial receptor may modulate apoptosis in the epidermis; its increased expression in differentiated epidermal layers may represent a novel mechanism of natural skin protection against free radical damage generated by ultraviolet exposure.

Adult↗
PubMed1999

Ultraviolet light and dendritic cells.

The ultraviolet (UV) spectrum is divided into UVC (200-280 nm), UVB (280-320 nm) and UVA (320-400 nm). Of these only UVB and UVA are of environmental significance since UVC is effectively absorbed by ozone in the earth's atmosphere. UVB wavelengths penetrate the epidermis and are almost completely absorbed in the upper dermis while UVA penetrates to the deep dermis.

Animals↗
PubMed1999

Notalgia paresthetica: clinical, physiopathological and therapeutic aspects. A study of 12 cases.

Notalgia paresthetica (NP) is a common but often unrecognized neurocutaneous condition, with very few cases reported to date. It is characterized by pruritus localized in an area between D2 and D6 dermatomes, sometimes accompanied by sensory neuropathies and/or electrical conductivity disorders. Cutaneous pigmented patches and friction amyloidosis can arise with irritation. Some hereditary cases have been noted mainly in young patients, associated with multiple endocrine neoplasia type 2A. However, NP mainly occurs in older patients and most are sporadic pathologies linked with musculoskeletal compression of spinal nerves. Only capsaicin has shown some (but unfortunately only transient) efficacy in relieving NP symptoms. We present observations on 12 sporadic cases of NP. Spinal X-rays revealed dorsal arthrosis or spinal static disequilibrium in nine of these patients. Six patients underwent spinal and paraspinal ultrasound or radiation (better) physiotherapy, and the symptoms subsided in four of these cases. These results highlighted that spinal disorders could be a determining factor in NP, indicating that patients could benefit from physiotherapy.

Adrenal Cortex Hormones↗
PubMed1999

Tongue necrosis provoked by ergotamine tartrate and disclosing a giant cell arteritis.

A case of tongue necrosis induced by ergotamine tartrate is reported in a patient who was suffering from an unknown giant cell arteritis (GCA). The role of ergotamine in provoking tongue necrosis in temporal arteritis has only infrequently been considered. The hypothesis concerning ergotamine-induced vasospasm potentially being able to trigger a tongue necrosis in GCA is supported by the present case. This unusual complication warns us against uncritical prescription of this drug for elderly people suffering from migraine without considering GCA.

Aged↗
PubMed1998

[Allergy investigations in eczema].

Investigation of allergy is of major importance in the diagnosis of eczema. It is mainly based on patient history: personal and familial atopic antecedents, possible contact with allergens at the work-site, in the household or during leisure activities, or in topical medications, cosmetics or clothing. Among complementary examinations, detection of eosinophilia or elevated IgE has no practical application, but sometimes the presence of specific IgE can be useful. In fact, the most important examinations are skin tests, especially patch tests, which are indispensable in contact dermatitis, and in rare cases, patch tests.

Eczema↗