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P Loiseau

Publications and source records attributed to P Loiseau.

At least 19 recordsLinked to original sources
PubMed2006

Laser-beam smoothing induced by stimulated brillouin scattering in an inhomogeneous plasma.

We present results of two-dimensional simulations of the stimulated Brillouin scattering (SBS) of an optically smoothed laser beam propagating in an expanding plasma. In the weak damping limit, both backscattered and transmitted light waves exhibit an additional spatiotemporal incoherence, which is shown to be induced by SBS taking place in an inhomogeneous plasma. This mechanism is not related to laser-beam self-focusing and is thus complementary to plasma-induced smoothing [A. J. Schmitt and B. B. Afeyan, Phys. Plasmas 5, 503 (1998)]. The incoherence induced by SBS in the entrance part of the plasma could reduce the growth of parametric instabilities developing further inside the plasma and is able to significantly enlarge the spreading angle of the transmitted light. The angular width of the backscattered light is also found to be significantly larger than the aperture angle of the incident beam.

Journal Article↗
PubMed2006

Activating KIR genes are associated with CMV reactivation and survival after non-T-cell depleted HLA-identical sibling bone marrow transplantation for malignant disorders.

Combinations of HLA and killer immunoglobulin-like receptors (KIR) may affect outcome in T-cell depleted haematopoietic stem cell transplantation (HSCT). The KIR gene family includes inhibitory (KIR2DL and 3DL) and activating receptors (KIR2DS). Ligands are HLA-C (KIR2D) and HLA-Bw4 (KIR3DL1) for inhibitory KIR and are still unknown for activating KIR. The impact of activating KIR genotypes from donor and recipient is poorly documented in HSCT outcome. Here, HLA and KIR genotypes were determined in 131 pairs from non-T-cell depleted HLA-identical sibling HSCT. No effect of 'missing KIR ligand' was detected on acute graft-versus-host disease (GVHD), relapse, survival or infections even in myeloid malignancies. However, additional activating KIR genes in the donor compared to the recipient's genotype or an identity between donor and recipient activating KIR genotypes was associated with a lower transplant-related mortality (TRM) (P=0.005) and in a multivariate analysis with a better survival (P=0.02, HR=0.28; P=0.013, HR=0.29) and a lower incidence of cytomegalovirus (CMV) reactivation (P=0.009, HR=0.36). These data highlight the impact of donor-activating KIR genes on TRM, overall survival and CMV reactivation in HLA-identical sibling HSCT.

Adolescent↗
PubMed2006

Transient development of backward stimulated Raman and Brillouin scattering on a picosecond time scale measured by subpicosecond thomson diagnostic.

The excitation and the relaxation of the plasma waves and ion acoustic waves (IAW), respectively, driven by stimulated Raman (SRS) and Brillouin (SBS) backscatterings have been experimentally investigated with short-pulse lasers. The spectra have been obtained with a 0.3 ps time resolution. It is shown that SRS develops before SBS and suddenly decays around the peak of the pump, as the IAW reaches saturation. On this short time scale, electron kinetic effects play a major role for SRS saturation, contrary to ion dynamics. These results are supported by particle-in-cell simulations.

Journal Article↗
PubMed2006

[Antileishmanial activity of five 2- or 3- quinolines by enyne group].

INTRODUCTION: Leishmaniasis is an emergent orphan disease because of its co-infection with HIV AIDS. We report herein the in vitro biological evalution of five news quinolines, 2- or 3- substituted by an enyne group against Leishmania donovani (MHOM/ET/L82/LV9). PATIENTS AND METHODS: The quinolines has been synthesized by using a cross-coupling reaction between a chloroenyne and an organometallic coumpound in a presence of iron a "green" catalyst. Biological evalution is realized by a colorimetric method with the use of 3-(4,5-dimethylthiazol-2,5-diphényl)-tétrazolium bromide. RESULTS: Determination of the inhibitory concentrations as well as the minimal inhibitory concentrations has shown that the substitution by an enyne group made it possible to have a more important antileishmanial activity. In addition, we have seen that the -2 or the -3 position of the enyne group had no influence in the antileishmanial activity. CONCLUSION: Thus, we have shown the real interest of these quinolines which could be favourably compared with pentamidine, which is currently the reference product, and to consider the use of these quinolines in the treament of the leishmaniasis.

Humans↗
PubMed2005

No evidence for association between 1858 C/T single-nucleotide polymorphism of PTPN22 gene and primary Sjögren's syndrome.

One-third of first-degree relatives of patients with primary Sjögren's syndrome (pSS) suffer from other autoimmune diseases, including type I diabetes, systemic lupus erythematosus and autoimmune thyroiditis. Recently, 1858 C/T polymorphism of PTPN22 gene was reported to predispose to these autoimmune diseases. We decided to investigate whether PTPN22 gene polymorphism was also involved in the genetic predisposition to pSS in a case-control study, including 183 patients with pSS and 172 healthy controls. No significant differences in allele (T allele frequency: 7.7% in patients with pSS vs 7.8% in controls, P=0.9) and genotype frequencies of PTPN22 polymorphism were detected between patients with pSS and controls. PTPN 22 gene polymorphism was not associated with a specific pattern of autoantibody secretion either. Thus, 1858 C/T polymorphism of PTPN22 gene is not involved in genetic predisposition to pSS.

Autoantibodies↗
PubMed2004

Screening of New Caledonian and Vanuatu medicinal plants for antiprotozoal activity.

Sixty-seven extracts of 30 medicinal plants traditionally used in New Caledonia or Vanuatu by healers to treat inflammation, fever and in cicatrizing remedies were evaluated in vitro for their antiprotozoal activity against Leishmania donovani, Leishmania amazonensis and Trypanosoma cruzi. Among the selected plants, Pagiantha cerifera was the most active against both Leishmania species; four extracts were active against promastigotes of Leishmania donovani at EC(50) values inferior to 5 microg/ml. Garcinia pedicillata extract had an EC(50) value of 12.5 microg/ml against intracellular amastigotes of Leishmania amazonensis. Alone Amborella trichopoda reduced by more of 80% the trypomastigotes of Trypanosoma cruzi in the blood.

Animals↗
PubMed2004

Antiparasitic activities of medicinal plants used in Ivory Coast.

During an ethnopharmacological survey of antiparasitic medicinal plants used in Ivory Coast, 17 plants were identified and collected. Polar, non-polar and alkaloidic extracts of various parts of these species were evaluated in vitro in an antiparasitic drug screening. Antimalarial, leishmanicidal, trypanocidal, antihelminthiasis and antiscabies activities were determined. Among the selected plants, Anogeissus leiocarpus and Terminalia glaucescens were strongly active against Plasmodium falciparum. Lawsonia inermis, selectively prescribed against trypanosomiasis shows interesting trypanocidal activities as did other 15 plants. Anthelmintic activities were found for 10 active species and 2 species (Uvaria afzelli and Monodora myristica) were actives against mites.

Animals↗
PubMed2003

Stimulation of soil nitrification and denitrification by grazing in grasslands: do changes in plant species composition matter?

Stimulation of nitrification and denitrification by long term (from years to decades) grazing has commonly been reported in different grassland ecosystems. However, grazing generally induces important changes in plant species composition, and whether changes in nitrification and denitrification are primarily due to changes in vegetation composition has never been tested. We compared soil nitrification- and denitrification-enzyme activities (NEA and DEA, respectively) between semi-natural grassland sites experiencing intensive (IG) and light (LG) grazing/mowing regimes for 13 years. Mean NEA and DEA (i.e. observed from random soil sampling) were higher in IG than LG sites. The NEA/DEA ratio was higher in IG than LG sites, indicating a higher stimulation of nitrification. Marked changes in plant species composition were observed in response to the grazing/mowing regime. In particular, the specific phytomass volume of Elymus repens was lower in IG than LG sites, whereas the specific volume of Lolium perenne was higher in IG than LG sites. In contrast, the specific volume of Holcus lanatus, Poa trivialis and Arrhenatherum elatius were not significantly different between treatments. Soils sampled beneath grass tussocks of the last three species exhibited higher DEA, NEA and NEA/DEA ratio in IG than LG sites. For a given grazing regime, plant species did not affect significantly soil DEA, NEA and NEA/DEA ratio. The modification of plant species composition is thus not the primary factor driving changes in nitrification and denitrification in semi-natural grassland ecosystems experiencing long term intensive grazing. Factors such as trampling, N returned in animal excreta, and/or modification of N uptake and C exudation by frequently defoliated plants could be responsible for the enhanced microbial activities.

Animals↗
PubMed2003

Acaricidal activity of Uvaria versicolor and Uvaria Klaineana (Annonaceae).

Three Uvaria species, namely U. klaineana, U. mocoli and U. versicolor were tested in vitro against Dermatophagoides pteronyssinus, the European house dust mite. The most active extracts were the Uvaria versicolor stems crude methanol and hexane extracts with EC(50) values of 0.095 g/m(2 )and 0.12 g/m(2), respectively. The bioassay-guided fractionation of the hexane extract led to the isolation of benzyl benzoate (1). which exhibited an EC(50) value of 0.045 g/m(2). A new fl avanone, versuvanone (2). and the known oxoaporphine liriodenine (3). were also isolated from this species and showed EC(50) values > 1.5 g/m(2). A weak acaricidal activity (0.85 g/m(2)) was observed for the dichloromethane extract of Uvaria klaineana, due to the presence of benzyl benzoate. Uvaria mocoli was inactive. The structures of compounds were elucidated using 2D-NMR techniques.

Dermatophagoides pteronyssinus↗
PubMed2003

Cytokine profiles in idiopathic pulmonary fibrosis suggest an important role for TGF-beta and IL-10.

Modulation of cytokine expression represents a potentially useful approach for the treatment of idiopathic pulmonary fibrosis (IPF). To identify potential targets for such intervention, semi-quantitative reverse transcriptase-polymerase chain reaction was used to compare the expression of messenger ribonucleic acids (mRNAs) coding for 17 cytokines in lung tissue obtained from patients with IPF at the time of diagnosis and control subjects. Some cytokines were also studied at the protein level by immunohistochemical techniques. mRNAs coding for all of the cytokines evaluated were detected in both control and fibrotic lung samples. Only transforming growth factor (TGF)-beta and interleukin (IL)-10 mRNAs were quantitatively increased in lung biopsies from patients with IPF compared with those of controls, results confirmed at the protein level by immunohistochemistry. Although mRNAs for platelet-derived growth factor (PDGF)-BB and keratinocyte growth factor (KGF) were expressed in similar amounts in lungs from patients with IPF and controls, localised accumulation of both factors was also observed in IPF. Hyperplastic alveolar epithelial cells were a prominent source of cytokines, where IL-10, PDGF-BB and KGF were present in increased amounts, although increased accumulation in fibroblasts, smooth-muscle cells and matrix components was also observed (PDGF-BB, TGF-beta). These results offer new insights into the cytokines produced in the lung in idiopathic pulmonary fibrosis and suggest that modulation of the production of transforming growth factor-beta and interleukin-10 may represent a potentially useful therapeutic strategy for this disabling disease.

Female↗
PubMed2003

[Long circulating nanocapsules: interest in the treatment of severe malaria with halofantrine].

The aim of the work was to develop a new submicronic delivery system that can be used with poorly water soluble drugs for which sustained circulating concentrations are necessary. This system consists of oily core surrounded by a shell made of a copolymer of poly (D,L-lactid) and poly (ethylene glycol). Covalent coupling between the hydrophylic poly (ethylene glycol) and poly (D,L lactid) and high molecular weight of the poly (ethylene glycol) chains yield long circulating particles after intra-venous administration in mice. Halofantrine, a very effective drug administrated for the treatment of severe malaria caused by Plasmodium, for which no injectable preparation exists. Results showed that percentage of loading, yield of encapsulation and physical stability were more favourable with surface modified nanocapsules. Release of halofantrine was clearly related to partition between oil and external medium. Serum proteins in the medium, increased halofantrine release from nanocapsules and poly (ethylene glycol) grafted nanocapsules reduced this phenomenum. The pharmacokinetics of the free drug was modified to maintain it in blood circulation. It is important to note that high plasma concentrations of halofantrine were correlated with higher activity against parasites in mice infected with Plasmodium berghei.

Animals↗
PubMed2003

[Antiparasitic effect of Senegalese Annonaceae used in traditional medicine].

Annonaceae is a large family of plants widely used in alimentation and traditional medicine. The interest of their study is raised up by the presence of biologically active substances among that the acetogenins which are specific to them. In Senegal, three species are widely used in traditional medicine for various indications and particularly in parasitic diseases: Annona senegalensis, Uvaria chamae and Xylopia aethiopica. The study of antiparasitical extracts from various organs showed an interesting activity of the fruits and leaves of Xylopia aethiopica on Leishmania donovani, the stem barks and roots of Uvaria chamae on Trypanosomia brucei and the roots of Annona senegalensis on the chloroquino-resistant strain of Plasmodium falciparum. Bioguided fractionation of the active extracts led to isolate Annonaceous acetogenins. Therefore, thirteen acetogenins, from the roots of Uvaria chamae and Annona senegalensis, were identified. The presence of acetogenins, substances with antiparasitical activity, could partly explain the biological proprieties of these various drugs.

Animals↗
PubMed2002

Hispano-Indian admixture in Paraguay studied by analysis of HLA-DRB1 polymorphism.

The genetic polymorphism of the Paraguayan population results from the admixture between South American Indians named Guaranis and Spaniards. In order to evaluate the genetic predominance in the Paraguayan population, we typed 50 healthy Paraguayans for HLA-DRB1 by molecular biology and compared their HLA-DRB1 polymorphism to that of the Guaranis and of two Spanish populations. Six significant differences of alleles frequencies were observed between Paraguayans and Guaranis--DRB1*01, 06 (13, 14), 15, 16, 07--whereas only one difference was observed with the Spaniards (DRB1*14). The DRB1*14 frequency was higher in Paraguayan than in the Spanish populations essentially due to the presence of DRB1*1402 related alleles (1402,06,13). These alleles are extremely rare in the Spanish populations whereas frequent in the Guaranis from Brazil and in South American Indian tribes living in the lymitrophe regions of Paraguay (Toba, Wichi and Terena). Thus, the presence of the DRB1*1402 related alleles (6%) in the Paraguayan population constitutes the major Indian contribution to the HLA-DR polymorphism of the Paraguayan population. The genetic distances between Paraguayans and the two Spanish populations were closer (.494 and .415) than that between Paraguayans and Guaranis (.958). Altogether these results suggest the predominance of the Spanish genetic in the Paraguayan population. Historical events are discussed to explain this predominance.

Alleles↗
PubMed2002

Progress report on new antiepileptic drugs: a summary of the Sixth Eilat Conference (EILAT VI).

The Sixth Eilat Conference on New Antiepileptic Drugs (AEDs) took place in Taormina, Sicily, Italy from 7th to 11th April, 2002. Basic scientists, clinical pharmacologists and neurologists from 27 countries attended the conference, whose main themes included dose-response relationships with conventional and recent AEDs, teratogenic effects of conventional and recent AEDs, update on clinical implications of AED metabolism, prevention of epileptogesis, and seizure aggravation by AEDs. According to tradition, the central part of the conference was devoted to a review of AEDs in development, as well to updates on AEDs, which have been marketed in recent years. This article summarizes the information presented on drugs in preclinical and clinical development, including carabersat (SB-204269), CGX-1007 (Conantokin-G), pregabalin, retigabine (D-23129), safinamide, SPD421 (DP-VPA), SPM 927, talampanel and valrocemide (TV 1901). Updates on fosphenytoin, gabapentin, lamotrigine, levetiracetam, oxcarbazepine, tiagabine, topiramate, vigabatrin, zonisamide, new formulations of valproic acid, and the antiepileptic vagal stimulator device are also presented.

Animals↗
PubMed2002

DPB1 disparities contribute to severe GVHD and reduced patient survival after unrelated donor bone marrow transplantation.

In order to evaluate the impact of HLA-DBP1 incompatibilities on the occurrence of acute graft-versus-host disease (GVHD) in unrelated hematopoietic cell transplantation, we studied 57 donor/recipient pairs characterized by their allelic identity for HLA-A, B, C, DRB1 and DQB1 and also for DRB3, 4, 5 loci and aimed to correlate DPB1 mismatches to already described risk factors for GVHD using multivariate Cox regression analysis. DPB1 identity between donor and recipient was observed in 24% and DPB1 compatibility (GVHD vector) in 42%. Two factors were independently associated with severe acute GVHD: two DP incompatibilities (RR = 8.25, 95% confidence interval (CI): 1.67-40.10, P = 0.010) and disease risk (RR = 10.23, 95% CI: 1.12-93.13, P = 0.012). Two DPB1 incompatibilities appeared also to be a factor in poorer survival independent of its effect on acute GVHD (RR = 4.97, 95% Cl: 1.80-13.71, P = 0.002). A correlation between acute GVHD and matching for each individual DPB1 polymorphic region and for residue 69 of the DP beta molecule, which seems to be a key residue in the alloimmune response, was not observed. Our data indicate that the outcome of unrelated hematopoietic cell transplantation in terms of GVHD but also survival, could be improved through HLA-DPB1 matching or at least by avoiding two DPB1 mismatches.

Adolescent↗
PubMed2002

Epistasis between DSG1 and HLA class II genes in pemphigus foliaceus.

Pemphigus foliaceus (PF) is a rare and severe cutaneous autoimmune disease caused by autoantibodies directed against desmoglein 1 (DSG1), a desmosomal adhesion glycoprotein. We previously showed that the DSG1 gene is polymorphic and that a coding synonymous T/C single nucleotide polymorphism at position 809 is associated with PF. To determine whether the disease occurred as a consequence of complex genetic interactions, we simultaneously examined the contribution of major histocompatibility complex (MHC) class II and DSG1 polymorphisms to PF susceptibility. Our analysis performed in 31 PF patients and 84 healthy controls first confirmed the previously reported common DRB1*04 and DRB1*14 genetic background in PF and individualized DRB1*0102, DRB1*0402 and DRB1*0406, and DRB1*1404 as susceptibility MHC class II alleles in French Caucasian PF patients. It also showed that the C/C(809) genotype was associated with PF. Combined analysis of HLA class II and DSG1 polymorphisms with several distinct statistical methods including logistic regression, showed that the DRB1*04 allele and the C/C(809) genotype interact to confer a higher susceptibility to PF. These data demonstrate the role of epistasis between individual genes in PF susceptibility and illustrate the genetic complexity of organ-specific autoimmune diseases.

Autoantigens↗
PubMed2001

Both genetic and clinical factors predict the development of graft-versus-host disease after allogeneic hematopoietic stem cell transplantation.

BACKGROUND: Graft-versus-host disease is the main complication of hematopoietic stem cell transplantation. Recently, pro- and anti-inflammatory cytokines and mismatches of minor histocompatibility antigens between HLA-identical sibling donor/recipient pairs have been implicated in the development of acute graft-versus-host disease. It is not known, however, whether these factors are independent of other clinically recognized risk factors such as age and disease stage. METHODS: In this study, we searched for risk factors of acute graft-versus-host disease using multivariate Cox regression analysis in 100 consecutive patients who underwent allogeneic stem cell transplantation from an HLA-identical sibling donor. Eight polymorphisms from five different cytokine genes were studied (tumor necrosis factor alpha, tumor necrosis factor beta, interleukin (IL) 6, IL-10, and interferon gamma). Mismatches for the minor histocompatibility antigen HA-1 were searched in HLA-A*0201 individuals. In addition to these new risk factors, patient, donor, disease, and transplant risk factors were analyzed by multivariate analysis using the Cox proportional hazards model. RESULTS: Acute graft-versus-host disease was independently associated with IL-10 gene polymorphisms both from the recipient (relative risk=7.9, P<0.0001) and the donor (relative risk=3.5, P=0.02), a donor's positive serology for cytomegalovirus, and HA-1 mismatches in HLA-A*0201 individuals (relative risk=2.8, P=0.05). Chronic graft-versus-host disease was independently associated with IL-6 gene polymorphism from the recipient (relative risk=4.2, P=0.02), older age (relative risk=2.5, P=0.0009), and previous acute graft-versus-host disease (relative risk=9.7, P=0.003). CONCLUSION: In addition to previously described clinical risk factors, genetic risk factors are independently associated with the risk of developing graft-versus-host disease and may, thus, be considered for the selection of the donor.

Adolescent↗