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Sample records for des melanocytes dans

  1. Transport quantique dans des nanostructures

    NASA Astrophysics Data System (ADS)

    Naud, C.

    2002-09-01

    structure des oscillations de conductance en fonction du flux du champ magnétique de période h/e dont l'amplitude est beaucoup plus importante que celle mesurée sur un réseau carré de même dimension. Cette différence constitue une signature d'un effet de localisation induit par le champ magnétique sur la topologie mathcal{T}3. Pour des valeurs spécifiques du champ magnétique, du fait des interférences destructives Aharonov-Bohm, la propagation des fonctions d'ondes est limitée à un ensemble fini de cellule du réseau appelé cage. De la dépendance en température des oscillations de période h/e mesurées sur le réseau mathcal{T}3 nous avons tiré une longueur caractéristique qui peut être rattachée au périmètre des cages. Un phénomène inattendu fut l'observation, pour des champs magnétiques plus importants, d'un doublement de fréquence des oscillations. Ces oscillations de période h/2e pouvant avoir une amplitude supérieure aux oscillations de période h/e, une interprétation en terme d'harmonique n'est pas possible. Enfin, l'influence de la largeur électrique des fils constituant le réseau et donc celle du nombre de canaux par brin a été étudiée en réalisant des grilles électrostatique. Les variations de l'amplitude des signaux en h/e et h/2e en fonction de la tension de grille ont été mesurés.

  2. Transport de paires EPR dans des structures mesoscopiques

    NASA Astrophysics Data System (ADS)

    Dupont, Emilie

    Dans cette these, nous nous sommes particulierement interesses a la propagation de paires EPR1 delocalisees et localisees, et a l'influence d'un supraconducteur sur le transport de ces paires. Apres une introduction de cette etude, ainsi que du cadre scientifique qu'est l'informatique quantique dans lequel elle s'inscrit, nous allons dans le chapitre 1 faire un rappel sur le systeme constitue de deux points quantiques normaux entoures de deux fils supraconducteurs. Cela nous permettra d'introduire une methode de calcul qui sera reutilisee par la suite, et de trouver egalement le courant Josephson produit par ce systeme transforme en SQUID-dc par l'ajout d'une jonction auxiliaire. Le SQUID permet de mesurer l'etat de spin (singulet ou triplet), et peut etre forme a partir d'autres systemes que nous etudierons ensuite. Dans le chapitre 2, nous rappellerons l'etude detaillee d'un intricateur d'Andreev faite par un groupe de Bale. La matrice T, permettant d'obtenir le courant dans les cas ou les electrons sont separes spatialement ou non, sera etudiee en detail afin d'en faire usage au chapitre suivant. Le chapitre 3 est consacre a l'etude de l'influence du bruit sur le fonctionnement de l'intricateur d'Andreev. Ce bruit modifie la forme du courant jusqu'a aboutir a d'autres conditions de fonctionnement de l'intricateur. En effet, le bruit present sur les points quantiques peut perturber le transport des paires EPR par l'intermediaire des degres de liberte. Nous montrerons que, du fait de l'"intrication" entre la charge de la paire et le bruit, la paire est detruite pour des temps longs. Cependant, le resultat le plus important sera que le bruit perturbe plus le transport des paires delocalisees, qui implique une resonance de Breit-Wigner a deux particules. Le transport parasite n'implique pour sa part qu'une resonance de Breit-Wigner a une particule. Dans le chapitre 4, nous reviendrons au systeme constitue de deux points quantiques entoures de deux fils

  3. Etude theorique et experimentale des evaporateurs de dioxyde de carbone operant dans des conditions de givrage

    NASA Astrophysics Data System (ADS)

    Bendaoud, Adlane Larbi

    Les evaporateurs de refrigeration sont surtout du type tube a ailettes, appeles serpentins, et fonctionnent dans l'une des conditions suivantes: seche, humide ou avec formation de givre. Il a ete demontre que la formation du givre sur la paroi exterieure de l'echangeur engendre une surconsommation energetique a cause des operations de degivrage puisque 15 a 20% seulement de la chaleur produite sert au degivrage tandis que le reste est dissipee dans l'environnement [1]. Avec l'avenement des nouveaux refrigerants, moins nocifs envers l'environnement, l'industrie du froid se trouve penalisee du fait que peu ou pas de composantes mecaniques (compresseur, pompe, echangeur...etc.) adaptees sont disponibles [3]. Il s'agit pour la communaute des frigoristes de combler ce retard technologique en redeveloppant ces composantes mecaniques afin qu'elles soient adaptees aux nouveaux refrigerants. Dans cette optique, et afin de mieux comprendre le comportement thermique des evaporateurs au CO2 fonctionnant dans des conditions seches, qu'un groupe de chercheurs du CanmetENERGIE avaient lance, en 2000, un programme de R & D. Dans le cadre de programme un outil de simulation des evaporateurs au CO2 a ete developpe et un banc d'essai contenant une boucle secondaire de refrigeration utilisant le CO2 comme refrigerant a ete construit. Comme continuite de ce travail de recherche, en 2006 ce meme groupe de recherche a lance un nouveau projet qui consiste a faire une etude theorique et experimentale des evaporateurs au CO2 operants dans des conditions de givrage. Et, c'est exactement dans le cadre de ce projet que se positionne ce travail de these. Ce travail de recherche a ete entrepris pour mieux comprendre le comportement thermique et hydrodynamique des serpentins fonctionnant dans des conditions de givrage, l'effet des circuits de refrigerant ainsi que celui des parametres geometriques et d'operation. Pour cela, un travail theorique supporte par une etude experimentale a ete effectue

  4. Altération des sulfures des granulats dans les chaussées

    NASA Astrophysics Data System (ADS)

    Jigorel, A.; Jauberthie, R.

    2002-07-01

    Sulfides present in hornsfeld aggregates, used in light pavanent construction in contact with humid air alter rapidly. Crystallisation of sulfates at the interface of bitumastic material and sub-base creates serious problems (intumescence and crazing) that can lead to a total reconstruction of the project (roads, sidewalks, sports areas, etc). The sulfides in the aggregates and the sulfates produced due to alteration are studied by SEM and XRD. The results show that the intensity of this phenomenon is linked to the nature and the crystallinity of the sulfides. The evolution of the sulfates formed during this alteration process is slow and complex. In new pavements (3 years) the sulfates have a pulverised appearance and consist mostly of epsomite, associated with pickeringite and halotrichite. In older pavements (20 years) the sulfates form a fibrous concretion consisting of pickeringite and small quantities of halotrichite. Les sulfures présents dans les granulats élaborés à partir de cornéen nes s'altèrent rapidement dans les chaussées légères en présence d'air humide. La cristallisation des sulfates à l'interface enrobé-couche de fondation crée des désordres si importants (intumescences, faiençage) qu'il est bien souvent nécessaire d'assurer la réfection totale des ouvrages (routes, trottoirs, plateaux sportifs...). Les sulfures des granulats et les sulfates issus du processus d'altération ont été étudiés par diffractométrie X et examen su Microscope Electronique à Balayage équipé de microanalyse X. Les résultats montrent que !intensité des désordres est liée à la nature et à la cristallinité des sulfures. Les sulfates formés évoluent su cours du processus d'altération qui est long et complexe. Dans les chaussées récentes (3 ans) ils ont un aspect pulvérulent et sont constitués d'epsomite dominante associée à de la pickeringite et à de l'halotrichite. Dans les chaussées plus anciennes (20 ans) ils forment des concr

  5. Rôle des hyrates dans la formation de Titan et des satellites réguliers

    NASA Astrophysics Data System (ADS)

    Mousis, O.

    2001-12-01

    Cette these est dediee a l'etude de l'origine de Titan et de son atmosphere. Dans l'hypothese ou la subnebuleuse de Saturne etait geometriquement mince, le modele de disque turbulent utilise, derive des travaux de Dubrulle (1993), est moins dense que le modele de Prinn et Fegley (1981). De ce fait, les conversions de Co en CH4 et de N2 en NH3 ont ete inhibees dans la subnebuleuse, contrairement a ce qui est couramment admis pour interpreter la presence du methane dans l'atmosphere de Titan. C'est pourquoi nous avons developpe un nouveau scenario de la formation de titan, qui tient compte simultanement des contraintes resultant de la chimie de la subnebuleuse et des abondances de CH4, N2 et CH3D mesurees dans l'atmosphere du satellite. Nous faisons l'hypothese que ces gaz proviennent initialement de la vaporisation du nuage presolaire, qui s'effondra et forma le Soleil et son disque environnant. Lors du refroidissement de la nebuleuse, les volatils auraient ete pieges sous formes de clathrates d'hydrates dans les grains, puis dans les planetesimaux qu'ils formerent. Les planetesimaux hydrates a l'origine de la formation de Titan seraient alors des rescapes de l'effondrement hydsrodynamique de la feeding zone de Saturne. Ce scenario a ete applique aux subnebuleuses de Jupiter et d'Uranus, et a apporte un certain nombre de contraintes sur la formation des satellites reguliers de ces planetes. Le temps et la zone de formation des grains cometaires ont egalement ete estimes dans la nebuleuse solaire. Enfin, l'etude experimentale de la temperature de fusion du dihydrate d'ammoniac dans la gamme des hautes pressions a apporte des nouvelles donnees thermodynamiques qui permettront d'ameliorer les modeles de l'interieur de Titan.

  6. Etude des phenomenes de penetration des especes chimiques dans les revetements cathodiques des cuves d'electrolyse de l'aluminium

    NASA Astrophysics Data System (ADS)

    Brisson, Pierre-Yves

    Cette these decrit l'etude effectuee sur les phenomenes d'insertion du sodium et de penetration du bain electrolytique dans les revetements cathodiques des cuves d'electrolyse de l'aluminium. L'etude fut effectuee a l'aide d'un montage permettant d'effectuer l'electrolyse en laboratoire. Trois types de revetement cathodiques furent etudies : des blocs semi-graphitique, des blocs graphitiques et des blocs graphitises. L'insertion du sodium dans les trois differents types de blocs fut etudiee a l'aide de la spectrometrie des photoelectrons X (XPS). L'analyse a permis de mettre en evidence deux formes de sodium dans l'anthracite et la phase liante des materiaux semi-graphitiques et graphitiques, indiquant qu'une fraction du sodium se retrouve sous forme adsorbee dans les micropores des materiaux alors que l'autre fraction est inseree dans la structure cristalline du carbone. Dans les phases graphitiques (materiaux graphitises et graphitiques), seuls les micropores sont occupes par le sodium Ce resultat explique la tendance observee selon laquelle l'ajout de graphite dans les blocs permet d'abaisser le gonflement sodique. Les mecanismes de penetration du bain dans le reseau poreux des materiaux furent etudies en microscopie electronique et en diffraction des rayons X sur des echantillons apres differents temps d'electrolyses et en variant l'atmosphere (soit sous argon ou sous azote). Ces analyses ont permis d'identifier le mecanisme conduisant a la mouillabilite du bain sur le carbone en fonction de l'atmosphere entourant l'electrolyse. Ainsi, sous azote, la formation de NaCN dans les pores des materiaux par reactions entre le sodium et l'azote permet une mouillabilite accrue du bain alors qu'en absence d'azote (sous argon), le carbure d'aluminium, formes a la surface des pores, joue un role similaire. Dans ce dernier cas, la penetration du bain est moins rapide etant donnee la necessite de toujours amener des especes contenant de l'aluminium en tete du front de

  7. Apport des moyens endoscopiques dans la dilatation des sténoses caustiques de l’œsophage

    PubMed Central

    Seydou, Togo; Abdoulaye, Ouattara Moussa; xing, Li; Zi, Sanogo Zimogo; sekou, Koumaré; Wen, Yang Shang; Ibrahim, Sankare; Sekou, Toure Cheik Ahmed; Boubacar, Maiga Ibrahim; Saye, Jacque; Jerome, Dakouo Dodino; Dantoumé, Toure Ousmane; Sadio, Yena

    2016-01-01

    Introduction Toutes les sténoses symptomatiques de l’œsophage peuvent être dilatées par voie endoscopique. Nous évaluons l'apport des moyens endoscopiques dans la prise en charge de la dilatation œsophagienne pour sténose caustique de l’œsophage (SCO) au Mali. Méthodes IL s'agissait d'une étude descriptive et prospective réalisée dans le service de chirurgie thoracique à l'hôpital du Mali. Au total 46 dossiers cliniques de patients on été enregistrés et subdivisés en 4 groupes en fonction de la topographie des lésions cicatricielles. Le nombre de cas d'assistance endoscopique réalisé a été déterminé afin de comprendre l'apport des moyens endoscopiques dans le succès de la dilatation des SCO. Pour les 2 différentes méthodes de dilatation utilisées, le résultat du traitement et le coût ont comparés. Résultats La FOGD a été utilisée dans 19 cas (41.30%) de dilatation avec la bougie de Savary Guillard et dans 47.82% des cas dans la dilatation de Lerut. La vidéo-laryngoscopie a été utilisé 58.69% des cas de dilatation à la bougie de Lerut. Le passage de guide métallique et / ou de fil-guide a été réalisée dans 39.13% avec la vidéo laryngoscopie et dans 58.68% avec la FOGD. Dans la comparaison des deux méthodes, il existe une différence significative dans la survenue des complications (p=0.04075), l'anesthésie générale (p=0.02287), l'accessibilité à la méthode (p=0.04805) et la mortalité (p=0.00402). Conclusion La SCO est une pathologie grave et sous évaluée au Mali. Les moyens endoscopiques contribuent considérablement au succès de la dilatation œsophagienne pour sténose caustique dans les différentes méthodes utilisées. PMID:27200129

  8. Apport de l'imagerie dans le diagnostic des sacroiliites infectieuses : à propos de 19 cas

    PubMed Central

    Abid, Hanen; Chaabouni, Salim; Frikha, Faten; Toumi, Nozha; Souissi, Basma; Lahiani, Dorra; Bahloul, Zouhir; Ben Mahfoudh, Khaireddine

    2014-01-01

    Les sacro-iliites infectieuses méritent d’être mieux connues. Leur diagnostic est souvent retardé en raison d'une symptomatologie trompeuse et des diffcultés d'exploration de l'articulation sacro-iliaque. Notre travail est basé sur une étude rétrospective portant sur les cas de SII, recueillis sur une période comprise entre 1997 et 2008 dans notre centre universitaire Sfax-Tunisie. Le diagnostic de sacro-iliite était retenu en présence d'arguments cliniques et radiologiques d'atteinte sacroiliaque. Nous rapportons dix neuf cas de sacroiliites infectieuses (10 hommes et 9 femmes), avec un âge moyen de 32 ans. L'atteinte était unilatérale dans tous les cas. Les radiographies standard faites dans tous les cas ont été suggestives dans 14 cas et normales dans les autres cas. La TDM faite dans 13 cas a montré, un abcès des parties molles dans 8 cas et un séquestre osseux dans 2 cas. L'IRM réalisée dans 8 cas, a objectivé une infiltration des parties molles dans tous les cas et un abcès dans 3 cas. Le germe a été identifié dans 9 cas (3 cas de tuberculose, 3 cas de brucellose, 2 sacro-iliites à pyogène et un cas de candidose). Cette identification était faite par biopsie dans 3 cas, hémocultures dans 2 cas, prélèvement au niveau de la porte d'entrée dans 1 cas et sérodiagnostic dans 3 cas. Pour les autres cas, l'origine pyogène a été retenue sur des arguments cliniques et biologiques. L'imagerie joue un rôle primordial dans le diagnostic précoce et l'orientation étiologique d'une sacroiliite infectieuse. PMID:25120884

  9. La prévention des blessures dans les terrains de jeux

    PubMed Central

    Fuselli, Pamela; Yanchar, Natalie L

    2012-01-01

    RÉSUMÉ Dans un climat d’inquiétude croissante à l’égard de l’obésité juvénile et de l’inactivité, les terrains de jeux permettent aux enfants d’être actifs. Ils comportent toutefois aussi des risques, les blessures causées par des chutes étant de loin les plus courants. Les recherches démontrent la possibilité de réduire les blessures dans les terrains de jeux si on abaisse la hauteur des structures de jeu et si on utilise des surfaces molles et profondes pour amortir les chutes. L’Association canadienne de normalisation a publié des normes volontaires qu’elle a mises à jour plusieurs fois pour tenir compte de ces risques. Afin de contribuer à les réduire, les parents peuvent respecter des stratégies simples. Le présent document de principes souligne le fardeau des blessures subies dans les terrains de jeux. Il procure également aux parents et aux dispensateurs de soins des occasions de réduire l’incidence et la gravité des blessures grâce à l’éducation et à la défense d’intérêts, ainsi que de mettre en œuvre des normes de sécurité probantes et des stratégies plus sécuritaires dans les terrains de jeux locaux. Enfin, il remplace le document de principes de la Société canadienne de pédiatrie publié en 2002 sur le sujet.

  10. Place du Lambeau Interosseux Posterieur dans sa Variante Aponevrotique dans le Traitement des Sequelles de Brulure de la Face Dorsale de la Main

    PubMed Central

    Achbouk, A.; Khales, A.; Oufkir, A.; Ihrai, H.

    2010-01-01

    Summary Le lambeau interosseux postérieur dans sa variante aponévrotique est un outil très intéressant dans le traitement des séquelles de brûlures de la face dorsale de la main. Les Auteurs cherchent, à travers un cas clinique et une revue de la littérature, à replacer cette variante dans l'arsenal thérapeutique. PMID:21991207

  11. Transition de phase quantique de type verrouillage-deverrouillage dans les canaux lineaires coherents des phases en rayures dans les doubles puits quantiques sous champ magnetique perpendiculaire

    NASA Astrophysics Data System (ADS)

    Faribault, Alexandre

    On peut creer un gaz electronique bidimensionnel en utilisant le potentiel de confinement d'une couche mince d'un semiconducteur dans un substrat fait d'une autre semiconducteur de gap plus eleve. L'ajout d'un champ magnetique perpendiculaire au plan de confinement modifie de facon drastique les proprietes du gaz electronique. Pour des densites et des valeurs du champ magnetique adequatement choisies, on obtient un etat fondamental en onde de densite de charge. Dans un systeme compose de deux de ces gaz bidimensionnels suffisamment rapproches l'un de l'autre, on prevoit theoriquement l'existence d'un etat fondamental compose d'une onde de densite de charge dans chacun des puits et d'une serie de regions lineaires ou l'on a une delocalisation coherente des electrons entre les deux puits. Dans cette these, on etudie le comportement a temperature nulle de cet etat fondamental en rayures coherentes. L'etude numerique des modes collectifs de ces phases laisse croire qu'un deverrouillage des canaux coherents est envisageable dans ce systeme. Afin d'etudier cette possibilite, nous construisons d'abord un modele effectif de canaux quasi-unidimensionnels couples qui permettent de reproduire correctement les excitations collectives a basse energie de la phase en rayures coherentes du double puits quantique. Dans un systeme de coordonnees adequatement choisi, ces excitations peuvent etre decrites par des ondes de pseudospin. Les parametres de ce modele effectif simple peuvent etre extraits des calculs des fonctions de reponse realises dans l'approximation Hartree-Fock dependante du temps (appelee aussi Generalized Random Phase Approximation). On constate l'efficacite de ce modele a decrire la dynamique basse energie du systeme pour une certaine plage de distances inter-puits. En retirant de ce modele les contributions a l'hamiltonien provenant des couplages de type Josephson entre les canaux, on obtient alors un systeme ou les canaux sont deverrouilles. Un traitement en

  12. Etude theorique des fluctuations structurales dans les composes organiques a dimensionnalite reduite

    NASA Astrophysics Data System (ADS)

    Dumoulin, Benoit

    Les systemes a dimensionnalite reduite constituent maintenant une branche entiere de la physique de la matiere condensee. Cette derniere s'est developpee rapidement au cours des dernieres annees, avec la decouverte des materiaux organiques qui presentent, justement, des proprietes physiques fortement anisotropes. Cette these presente une etude en trois parties de plusieurs composes organiques qui, bien que tres differents du point de vue de leurs compositions chimiques et de leurs proprietes physiques a haute temperature, subissent tous une instabilite structurale a tres basse temperature. De plus, dans chacun des cas, l'instabilite structurale est precedee d'un important regime fluctuatif a partir duquel les proprietes physiques changent de maniere significative. Notre etude suit un ordre chronologique inverse puisque nous nous attardons en premier lieu au cas de composes recemment decouverts: les composes de la famille des (BCPTTF)2X (X = PF6 , AsF6). Ces derniers sont des isolants magnetiques a la temperature ambiante et subissent une instabilite structurale de type spin-Peierls a une temperature appelee TSP. En particulier, nous nous interessons a l'etude des proprietes physiques de ces systemes dans le regime fluctuatif, qui precede cette instabilite. Notre etude theorique nous permet de comprendre en detail comment ces systemes s'approchent de l'instabilite struturale. Dans la seconde partie de cette these, nous etudions le regime fluctuatif (pre-transitionnel) observe experimentalement dans le compose de (TMTTF)2PF6. Ce compose organique, dont la structure s'apparente aux sels de Bechgaard, subit une instabilite de type spin-Peierls a une temperature T SP = 19K. Bien que ce compose possede la particularite d'etre un bon conducteur a la temperature ambiante, il subit une transition de type Mott-Hubbard a une temperature Trho ≈ 220K et devient alors un isolant magnetique, analogue aux composes de la famille des (BCPTTF)2X. Le regime fluctuatif precedant l

  13. Effects of diethylstilbestrol on the proliferation and tyrosinase activity of cultured human melanocytes

    PubMed Central

    TANG, JIANBING; LI, QIN; CHENG, BIAO; HUANG, CHONG; CHEN, KUI

    2015-01-01

    The aim of the present study was to observe the effects of different exogenous estrogen diethylstilbestrol (DES) concentrations on the human melanocyte proliferation and tyrosinase activity. Skin specimens were obtained following blepharoplasty, and the melanocytes were primary cultured and passaged to the third generation. The melanocytes were seeded in 96-well plates, each well had 5×103 cells. The medium was changed after 24 h, and contained 10−4-10−8 M DES. After the melanocytes were incubated, the proliferation and tyrosinase activity were detected by the MTT assay and L-DOPA reaction. DES (10−8-10−6 M) enhanced the proliferation of cultured melanocytes. The intensity was positively correlated with the concentration of drug. DES, >10−5 M, inhibited the melanocytes proliferation or even produced the toxicity effect. Following the addition of 10−6 M DES to the medium, the tyrosinase activity of melanocytes was significantly increased, with P<0.05. In conclusion, a certain concentration of DES promoted the proliferation of melanocytes, enhanced the activity of tyrosinase and promoted pigment synthesis of melanocytes, with the optimal concentration of 10−6 M. PMID:26171155

  14. Migration pelvienne de broche guide dans la chirurgie des fractures de hanche: à propos de 3 cas

    PubMed Central

    Guèye, Mohamadou Lamine; Thiam, Ousmane; Touré, Alpha Oumar; Seck, Mamadou; Cissé, Mamadou; Kâ, Ousmane; Dieng, Madieng; Dia, Abderahmane; Touré, Cheikh Tidiane

    2015-01-01

    La migration de matériel d'ostéosynthèse est une complication bien connue du traitement chirurgical des fractures. Toutefois, la migration pelvienne de broche guide dans la chirurgie des fractures de la hanche est un incident rare et potentiellement grave. Nous rapportons 3 observations dans lesquelles on notait une migration de broche guide dans le pelvis lors d'une ostéosynthèse dela hanche de type DHS. L'indication chirurgicale était une fracture per-trochantérienne dans 2 cas et une fracture du col fémoral type 4 de Garden dans 1 cas. Une minilaparotomie permettait d'objectiver une plaie du ligament large gauche et un hématome ligamentaire dans 1 cas, tandis que dans les 2 autres cas, il n'y avait pas de lésion viscérale. L'extraction de la broche a été effectuée dans les 3 cas. Les suites opératoires ont été simples chez tous les patients. PMID:26327949

  15. L'Apport de la Greffe de Peau Totale dans le Traitement des Sequelles des Brulures de la Main: a Propos de 14 Cas

    PubMed Central

    Ettalbi, S.; Ibnouzahir, M.; Rachid, M.; Bahaichar, N.; Boukind, H.

    2007-01-01

    Summary La main est fréquemment exposée aux brûlures, ce qui entraîne des séquelles cutanées. A partir d'une série de 14 patients suivis dans notre service sur une année, nous avons essayé d'établir la simplicité, l'efficacité et le rôle de la greffe de peau totale dans le traitement de ces séquelles (les organes nobles ne sont pas mis à nu). La greffe de peau totale associée à une rééducation efficace permet aux patients de reprendre la mobilité des mains dans les brefs délais. PMID:21991094

  16. Interpretation des donnees de flux de chaleur et de gravite dans le bouclier Canadien

    NASA Astrophysics Data System (ADS)

    Cheng, Li Zhen

    2000-10-01

    Le champ geothermique du Bouclier Canadien est caracterise par un flux moyen de 41 mW·m-2, qui suggere une production de chaleur moyenne dans la croute comprise entre 0.7 et 0.8 muW·m-3. Le flux de chaleur relativement faible favorise la stabilite du bouclier et lui a permis de resister a la deformation tectonique. Les variations du flux de chaleur a la surface sont dominees par la composition de la croute. Un flux eleve implique generalement une composition felsique et il est d'autant plus faible que la croute devient plus mafique. La production de chaleur en surface n'est pas representative de la production moyenne de la croute. Le flux de chaleur dans le Boucher Canadien ne depend donc pas de la production de chaleur en surface, mais depend de la composition principale de la croute. L'interpretation combinee des donnees geophysiques nous permet de determiner les variations de composition d'echelle crustale a partir desquelles il est possible d'etablir la structure de la croute. L'etude detaillee de l'Orogene de Trans-Hudson et de la Sous-province d'Abitibi a montre que le flux de chaleur, la gravite et la sismique lorsqu'elles sont combinees fournissent des contraintes efficaces pour determiner l'architecture crustale. En general, la croute est trop resistante pour se deformer par fluage, excepte tres localement. Le mode de deformation de la lithosphere continentale depend de la composition et du gradient geothermique. Nous montrons que la lithosphere du Bouclier Canadien demeure principalement fragile jusqu'a une profondeur de plus de 150 km. Une deformation ductile pourrait cependant etre possible localement a la base de la, croute, comme dans la ceinture de Thompson par exemple. Si l'on admet que la lithosphere peut resister a des contraintes allant jusqu'a 20 MPa (taux de deformation 3˙ < 10-15 s-1), l'epaisseur de la lithosphere est de l'ordre de 300 km pour la ceinture de Thompson et est superieure a 300 km pour la sous-province d'Abitibi. La resistance

  17. Prise en compte des ``courants de London'' dans la modélisation des supraconducteurs

    NASA Astrophysics Data System (ADS)

    Bossavit, Alain

    1997-10-01

    A model is given, in variational form, in which volumic “Bean currents”, ruled by Bean's law, and surface “London currents” coexist. This macroscopic model generalizes Bean's one, by appending to the critical density j_c a second parameter, with the dimension of a length, similar to London's depth λ. The one-dimensional version of the model is investigated, in order to link this parameter with the standard observable H-M characteristics On propose un modèle, sous forme variationnelle, associant des “courants de Bean” volumiques, décrits par la loi de Bean, et des “courants de London”, surfaciques. Ce modèle macroscopique généralise celui de Bean, caractérisé par le courant critique j_c, et fait intervenir un second paramètre, homogène à une longueur, analogue au λ de London. La version unidimensionnelle du modèle est étudiée en détail de manière à relier ce paramètre à l'observation des caractéristiques H-M usuelles.

  18. Un exemple de transfert de technologie dans le domaine des polymères conducteurs : le projet ``HYRA"

    NASA Astrophysics Data System (ADS)

    Parneix, J. P.; Miane, J. L.; Colin, T.; Ruffie, G.; Mege, J.

    1998-06-01

    The HYRA project is a response to the restructuration of local companies : these are purveyors of high technology military and spatial especially in the radars business. Furthermore, the development of mobile communications needs devices and materials in the millimeter range (from 20 to 100Ghz). The aim of the HYRA project is the development of materials with specific properties - particularly conducting materials - in the millimeter wave range. The results obtained on thermoplastic/conducting polymer composites are presented. Le projet HYRA répond à des préoccupations régionales liées à des restructurations industrielles : les industries régionales fournissant les marchés militaires et spatiaux disposent de techniques très performantes mais coûteuses, en particulier dans le domaine des radars. Par ailleurs le développement des communications mobiles a besoin de dispositifs et de matériaux dans tout le domaine millimétrique (de 20 à 100 Ghz). Le projet HYRA a pour but le développement de matériaux à propriétés spécifiques - en particulier conducteurs - dans ce domaine de fréquence. Les résultats obtenus sur des composites thermoplastiques/polymères conducteurs sont présentés.

  19. Sur la nature des absorbeurs dans l'interpretation transactionnelle de la mecanique quantique

    NASA Astrophysics Data System (ADS)

    Boisvert, Jean-Sebastien

    L'interpretation transactionnelle de la mecanique quantique est l'une des plus recentes propositions de description des phenomenes du microcosme. En accord avec les predictions de la mecanique quantique standard, l'interpretation transactionnelle propose une alternative a celle de Copenhague. Son principal avantage est qu'elle permet de visualiser les mecanismes sous-jacents a l'echange d'energie, de quantite de mouvement ou d'autres quantites quantiques entre un emetteur et un absorbeur. Ces echanges sont le resultat, a l'instar de la theorie de l'absorbeur de Wheeler et Feynman, de l'utilisation autant d'ondes avancees que retardees. Bien que l'interpretation transactionnelle n'ait pas attire la plus grande attention scientifique, plusieurs critiques lui ont ete adressees. Dans les annees 1990, differentes experiences a mesure sans interaction ont ete concues. Depuis, il a ete avance que la version originale de l'interpretation transactionnelle pouvait difficilement rendre compte de ce type d'experience et meme qu'elle n'est pas compatible avec le concept d'univers quadridimensionnel. La recherche de ce memoire par article consiste a montrer que lorsque l'on utilise systematiquement l'interpretation transactionnelle en considerant la configuration totale des absorbeurs (incluant l'absorbeur universel), il n'est pas necessaire de faire appel a une hierarchie de transactions comme certains l'ont propose.

  20. Étude des perturbations conduites et rayonnées dans une cellule de commutation

    NASA Astrophysics Data System (ADS)

    Costa, F.; Forest, F.; Puzo, A.; Rojat, G.

    1993-12-01

    The principles used in static conversion and the rise of the performances of the new switching devices contribue to increase the level of electromagnetic noises emitted by electronic converters. We have studied the way how these perturbations are created and coupled through their environment in conducted and radiated mode by a switching cell. This one can work in hard switching, zero current or voltage switching modes. We first outline the general problems of electromagnetic pollution and their metrology in converters. Then we describe the experimental environment. We analyse the mechanisms of generation of parasitic signals in a switching cell related to the electrical constraints and its switching mode. The simulated results, issued of the analytical models obtained, are confronted with the experimental ones. Then we show a method to calculate analytically the E and H near fields. It has been confirmed by experimental results. At last, we present, in a synthetic manner, the main results obtained, relative to the switching mode and the electrical constraints, using a new characterizing method. Theses results will allow the designer to incorporate the electromagnetic considerations in the conception of a converter. Les principes de commutation employés en conversion statique, l'évolution des performances statiques et dynamiques des composants, contribuent à faire des dispositifs de conversion statique de puissants générateurs de perturbations conduites et rayonnées. Nous nous sommes attachés à étudier les mécanismes de génération et de couplage des perturbations, tant en mode conduit que rayonné dans des structures à une seule cellule de commutation et fonctionnant selon les trois principaux modes de commutation : commutation forcée, à zéro de courant (ZCS), et à zéro de tension (ZVS). Après la mise en évidence de la problématique de pollution électromagnétique dans les structures et leur métrologie, nous décrivons l'environnement exp

  1. Apport de l'orientation clinique dans le diagnostic des hypertensions arterielles endocriniennes

    PubMed Central

    El Aziz, Siham; Chadli, Asma; Louda, Fatima; El Ghomari, Hassan; Farouqi, Ahmed

    2014-01-01

    L'hypertension artérielle d'origine endocrinienne représente une cause curable d'hypertension artérielle (HTA), ce qui en justifie le dépistage. Une orientation clinique est souhaitable afin de prescrire les bilans adéquats, notamment dans les pays en voie de développement. L'objectif de notre étude est décrire les aspects cliniques des patients ayant une HTA endocrinienne diagnostiquée au CHU de Casablanca. Méthodes: Il s'agit d'une étude descriptive rétrospective de 2004 à 2011, incluant tout patient ayant une HTA endocrinienne (en dehors des dysthyroïdies) admis en Endocrinologie. Les données concernant les facteurs cliniques, paracliniques et thérapeutiques ont été colligées. Au cours de la période étudiée, 53 cas d'HTA endocrinienne ont été admis, avec une age moyen au diagnostic de 39,3 ans et un sex-ratio F/H de 3,9. Trente patients (56.6%) ont un age ont un âge inférieur à 40 ans. On ne retrouve pas d'hérédité tensionelle chez 88.7% des patients. Les étiologies sont le Syndrome de cushing (41.5%), le phéochromocytome (32%), les adénomes somatotropes (15%) et les hyperaldostéronismes primaire (7.5%). L'HTA est essentiellement de grade un ou deux (69.8%), avec un retentissement cardio-vasculaire chez 11 patients (20.7%). Les patients ayant un SC avaient tous des signes cutanés spécifiques. Il s'agissait de sujets jeunes avec plusieurs facteurs de risque cardiovasculaire. Nous avons retrouvé un amaigrissement chez 37.5% des patients ayant un phéochromocytome avec un indice de masse corporel moyen de 20 kg/m2. L'HTA était permanente dans 5 cas de phéochromocytomes. Il n'existait pas d'hypokaliémie chez 50% des patients ayant un hyperaldostéronisme. Les signes cliniques des patients ayant une acromégalie étaient francs, avec un age moyen plus élevé de 50 ans. Nous avons noté une régression de l'HTA chez 59% de ces patients après guérison de l'endocrinopathie en cause. Plusieurs signes cliniques peuvent nous

  2. Amplification paramétrique de polaritons dans des microcavités semi-conductrices

    NASA Astrophysics Data System (ADS)

    Baas, A.; Karr, J.-P.; Courty, J.-M.; Giacobino, E.

    2002-06-01

    Nous étudions l'émission non linéaire de microcavités serai-conductrices en régime de couplage fort. Des expériences en régime d'excitation continue et résonante ont été récemment interprétées par un modèle de mélange paramétrique à quatre ondes de polaritons[1]. Nous avons retrouvé cette émission non linéaire dans une configuration nouvelle. Nous avons mis en évidence pour la première fois la dépendance en phase de l'émission, preuve de la cohérence du processus d'amplification. De plus, certaines quadratures du champ réfléchi ont des fluctuations réduites en dessous du bruit thermique, et proches de la limite quantique standardé[2

  3. Détermination du module d'Young dans des films minces de tungstène par diffraction des rayons X

    NASA Astrophysics Data System (ADS)

    Villain, P.; Goudeau, P.; Renault, P.-O.; Badawi, K. F.

    2002-07-01

    Elasticity of reduced dimension materials remains misunderstood since both experimental and theoretical studies on this subject are difficult to perform. Numerous experiments realised in the early 90's evidenced “elastic anomalies” in small period multilayer systems: “supermodulus”, breakdown of the Poisson's effect. The polemic raised by these observations lead us to develop a method to study the elastic constants in thin films on substrates; it combines X-ray diffraction and in situ tensile testing. This paper presents results on Poisson's ratio and Young's modulus measurement in 140nmW thin films; the obtained Young's modulus was smaller to the bulk material one whereas the Poisson's ratio was significantly larger than the bulk one. L'élasticité des matériaux de faible dimension demeure encore méconnue. Ceci tient entre autre à la difficulté de l'approche expérimentale et théorique. Dans les années 90, un grand nombre d'expériences ont mis en évidence des anomalies élastiques dans des systèmes multicouches de très faible période : supermodule, déviation à la loi de Poisson. La polémique soulevée par ces observations nous a amené à développer une méthode d'étude des constantes d'élasticité module d'Young et coefficient de Poisson dans les films minces sur substrats; elle combine la diffraction des rayons X et la déformation in situ. Cet article présente les résultats obtenus dans le cas de films de tungstène de 140nm d'épaisseur; la valeur mesurée pour le module d'Young est inférieure à celle du même matériau à l'état massif alors que pour le coefficient de Poisson, la valeur est plus grande.

  4. Identification des risques professionnels dans l'industrie textile en République Démocratique du Congo

    PubMed Central

    Kitronza, Panda Lukongo

    2014-01-01

    Introduction Le but de cette étude est de mettre en évidence les facteurs de risques professionnels liés aux conditions de travail. Méthodes Cette étude qualitative basée sur les entretiens de groupe a été réalisée par une équipe pluridisciplinaire dans l'industrie textile de la région du Est de la RDC; comprenant un médecin de travail, un médecin de santé publique, un toxicologue, deux infirmiers du centre hospitalier de l'usine, un représentant du comité d'hygiène et un technicien de prévention. La démarche méthodologique a consisté en des entretiens en groupe, des observations et visites guidées de lieux de travail de l'entreprise. Résultats Dans la culture du coton, les effets d'une forte exposition aux pesticides peuvent entraîner des intoxications aiguës, chroniques et voire le décès. Les autres risques sont les accidents de travail, les maladies professionnelles, les troubles psychologiques. Dans l'industrie, les travailleurs sont exposés aux risques liés à l'empoussiérage des fibres de coton, aux facteurs des risques traumatiques, physiques (bruits, vibration) et chimiques (acides forts, bases fortes, solvants et colorants minéraux), ainsi qu'aux risques psychosociaux. La pollution de l'environnement et l’écotoxicité inhérente à ces activités restent l'effet de l'usage des grandes quantités d'intrants agricoles, engrais et produits phytosanitaires. Conclusion Cette étude a permis de mettre en évidence les différents facteurs de risques auxquelles sont soumis les travailleurs textiles; ainsi que les risques environnementaux liés à cette activité. Cela est de nature à permettre la mise sur pied d'une stratégie efficace de prévention et de protection des travailleurs. PMID:25977736

  5. Les conseils des cliniciens canadiens en matière de commotion dans le sport sont-ils cohérents?

    PubMed Central

    Carson, James D.; Rendely, Alexandra; Garel, Alisha; Meaney, Christopher; Stoller, Jacqueline; Kaicker, Jatin; Hayden, Leigh; Moineddin, Rahim; Frémont, Pierre

    2016-01-01

    Résumé Objectif Comparer les connaissances et l’utilisation des recommandations concernant la prise en charge de la commotion dans le sport (CDS) démontrées par les spécialistes de la médecine du sport et de l’exercice (SMSE) et les urgentologues afin d’évaluer la réussite du transfert des connaissances sur la CDS au Canada. Conception Un sondage à choix multiples envoyé par courriel et autoadministré par des SMSE et des urgentologues. La validité du contenu du sondage a fait l’objet d’une évaluation. Contexte Canada. Participants Le sondage a été complété entre mai et juillet 2012 par des SMSE qui ont réussi l’examen menant au diplôme de l’Académie canadienne de la médecine du sport et de l’exercice et des urgentologues qui n’avaient pas ce diplôme. Principaux paramètres à l’étude La connaissance et l’identification des sources d’information sur la prise en charge des commotions, l’utilisation des stratégies de diagnostic de la commotion et l’utilisation d’une terminologie courante et cohérente dans l’explication des stratégies de repos aux patients après une CDS. Résultats Le taux de réponse était de 28 % (305 sur 1085). Les taux de réponse par les SMSE et les urgentologues se situaient respectivement à 41 % (147 sur 360) et 22 % (158 sur 725). Parmi les répondants, 41 % des urgentologues et 3 % des SMSE n’étaient pas au courant de l’existence de déclarations consensuelles sur la commotion dans le sport; 74 % des SMSE utilisaient « habituellement ou toujours » la version 2 de l’Outil d’évaluation de la commotion dans le sport (SCAT2), tandis que 88 % des urgentologues n’utilisaient jamais le SCAT2. Aucune réponse uniforme n’a été documentée à la question visant à connaître les meilleurs modes de repos cognitif. Conclusion Nous avons cerné des différences et un manque d’uniformité chez les SMSE et les urgentologues dans la mise en application des recommandations

  6. Hémophilie: état des lieux dans un service de pédiatrie dans la région de l'oriental du Maroc

    PubMed Central

    Benajiba, Noufissa; Boussaadni, Yousra EL; Aljabri, Mohammed; Bentata, Yassamine; Amrani, Rim; Rkain, Maria

    2014-01-01

    Pour les pays en voie de développement, l'hémophilie continue d’être une maladie de conséquence médicale et sociale désastreuse. Le but de ce travail est d'analyser le suivi d'une cohorte de patients hémophiles. Patients et méthodes: étude prospective étalée sur deux années et menée au centre référent d'hémophilie dans la région de l'orient du Maroc. Ont été inclus tous les patients présentant une hémophilie confirmée et âgé de moins de 18 ans. Résultats: sur 16 hémophiles, Quinze patients présentait une hémophilie A, l’âge moyen des patients était de 6,18 ans, la forme sévère, représentait 20,7%, la forme modérée: 33,3% et la forme mineure: 40%. Les circonstances de découverte étaient post circoncisionnelle chez 53,3% des patients, 20,7% post traumatique, 20% à l’âge de la marche; la durée d’évolution variait entre 2 mois et 10 ans. L'hémarthrose a été décrite au niveau des genoux, coudes et chevilles, avec une moyenne allant de 2 à 5 fois par an; l'arthropathie a été remarquée dans 33,3%. Le bilan immunologique a révélé des facteurs circulant inhibant chez deux patients. Le traitement était à base d'antalgiques, de plasma frais congelé. L'administration de facteurs VIII recombinés a été instaurée chez 40,6% des patients (plus de 90% des formes modérées et graves), grâce au programme national de prise en charge des hémophiles. Le décès était noté dans un seul cas lié à une hémorragie cérébrale. Conclusion: Nous insistons sur l'intérêt du programme national de prise en charge des hémophiles dernièrement instauré qui pourrait améliorer les conditions de vie de ces enfants. PMID:25404986

  7. Etude experimentale de la photoexcitation des colorants de type anthracene, azobenzene et thioindigo dans des matrices de cristaux liquides nematiques et smectiques

    NASA Astrophysics Data System (ADS)

    Saad, Bendaoud

    Nous avons étudié le comportement de différents colorants (tétracène et azobenzènes AZD3, DR1 et D2) dans des matrices de cristaux liquides (E7 et 5CB). Les résultats obtenus ont montré que la réorientation optique des molécules de cristaux liquides se produit à des intensités extrêmement faibles (~1 μW/cm 2). Nous avons attribué cet effet à l'interaction entre les molécules des colorants photoexcitées et celles des cristaux liquides hôtes. Ces interactions se produisent lorsque les molécules dichroïques exçitées transitent entre des états triplets intermédiaires tout en conduisant à la génération d'un nouveau moment optique géant, responsable de la réorientation des molécules. Le changement de la forme de la molécule du colorant, dû à l'isomérisation Trans-Cis , est à l'origine de la création de ce moment. Ce qui distingue notre réorientation moléculaire de celle obtenue sur d'autres systèmes hôtes-dopants est que les molécules sont repoussées du champ électrique de la lumière. Par ailleurs, cette réorientation est accompagnée d'une diffusion anisotrope des molécules excitées. Nous avons aussi étudié le cristal liquide PhBz rendu ferroélectrique en le dopant par des molécules thioindigos. En exploitant l'augmentation de la polarisation spontanée due à la photoisomérisation du colorant, nous avons pu réaliser un hologramme dynamique contrôlable par un champ optique assisté par une tension statique.

  8. Imagerie Resolue dans le Temps des Photons et Neutres Metastables Emis D'une Surface Par Stimulation Electronique

    NASA Astrophysics Data System (ADS)

    Leclerc, Gregoire

    L'appareil que nous presentons ici a ete mis au point pour permettre d'accumuler des images numeriques, resolues dans le temps, de la desorption par stimulation electronique (DSE) d'ions positifs et negatifs, de photons et de neutres metastables, tout en conservant des capacites de base de diffraction d'electrons lents (DEL) et de transmission d'electrons lents (TEL). Le spectrometre comporte un monochromateur d'electrons a secteur cylindrique de 127^ circ dont l'optique de sortie permet la focalisation du faisceau d'electrons sur une large gamme d'energies. Le detecteur consiste en un empilement de galettes de microcanaux et d'une anode resistive a encodage de division de charges. La reponse spatiale du detecteur a ete calibree et plusieurs causes de non-linearite ont ete localisees et corrigees. Des methodes de correction materielle et logicielle des distorsions spatiales sont presentees. La resolution temporelle des evenements est obtenue en pulsant le faisceau d'electrons, et de facon synchrone la detection, laquelle est couplee a un micro-ordinateur. La premiere partie de ce travail est consacree a la caracterisation du spectrometre et la presentation de nombreux parametres operationnels, obtenus soit au moment de la conception, soit experimentalement. Suit la presentation de donnees de DEL et de DSE pour le systeme Ar/Pt(111) en films minces a 15K. Les sequences temporelles d'images de metastables d'Ar desorbes ont revele la presence de plusieurs populations distinctes, ayant des distributions angulaires et distributions d'energie cinetique que nous avons pu separer. Les fonctions d'excitation de l'emission de photons et de la desorption de differentes composantes de metastables, ainsi que la dependance de ces signaux sur l'epaisseur des films d'Ar, sont aussi presentees et analysees. Les techniques que nous avons developpees ont permis de cerner les mecanismes en jeu pour la desorption et la luminescence.

  9. Apport de la biopsie radioguidée dans le diagnostic histopathologique des tumeurs de l'enfant: expérience de l'Hôpital d'Enfant de Rabat

    PubMed Central

    El Ochi, Mohamed Réda; Bellarbi, Salma; Rouas, Lamiae; Lamalmi, Najat; Malihy, Abderrahmane; Alhamany, Zaitouna; Cherradi, Nadia

    2015-01-01

    La biopsie radioguidée constitue une alternative à la biopsie chirurgicale invasive et à la cytologie pour le diagnostic des tumeurs pédiatriques. L'intérêt de notre étude est d’évaluer la valeur diagnostique des biopsies radioguidées examinées au laboratoire d'anatomopathologie de l'hôpital d'Enfants de Rabat (HER). L’étude a porté sur 78 biopsies radioguidées recueillies dans notre laboratoire entre janvier 2008 et décembre 2011. l’âge moyen des patients était de 5 ans et 10 mois avec une prédominance masculine (65,4%). La tumeur était abdominale dans 80% des cas, thoracique dans 15% cas, thoracique et abdominale dans 2,5% et sacrée dans 1,2%. Les biopsies étaient écho-guidées dans 90% des cas et scannoguidées dans 10% des cas. Le diagnostic histopathologique était posé dans 89% des cas. L'immuno-histochimie a été indiquée dans 35% des cas. Les diagnostics les plus fréquents étaient: tumeurs neuroblastiques (42 cas), lymphomes non hodgkiniens (10 cas), rhabdomyosarcomes (6 cas), autres (sarcome d'Ewing, néphroblastomes, tumeur myofibroblastique inflammatoire, maladies de Hodgkin, leucémie aiguë, hépatoblastome et ostéosarcome). Dans notre série, la biopsie radioguidée a permis un diagnostic histopathologique certain dans 89% des cas. Elle nécessite une étroite collaboration entre clinicien, radiologue et anatomopathologiste pour discuter son indication, afin de diminuer le nombre de biopsies peu ou non représentatives. PMID:26587165

  10. Modélisation des charges d'espace dans les isolants solides par une analyse spectrale

    NASA Astrophysics Data System (ADS)

    Haas, V.; Scouarnec, Ch.; Franceschi, J. L.

    1998-01-01

    A mathematical method based on spectral algebra is developped for the thermal modulation method. These methods permit to measure the space charge distribution in solid insulators. The modelling presented permits to evaluate the performances and the limitations of the measurement method. Une linéarisation par l'algèbre spectrale a été développée dans une méthode de modulation thermique pour mesurer la distribution des charges électriques dans les isolants solides. La modélisation présentée permet d'évaluer les performances et les limites tant numériques que physiques de la méthode de mesure.

  11. Melanocytes and Their Diseases

    PubMed Central

    Yamaguchi, Yuji; Hearing, Vincent J.

    2014-01-01

    Human melanocytes are distributed not only in the epidermis and in hair follicles but also in mucosa, cochlea (ear), iris (eye), and mesencephalon (brain) among other tissues. Melanocytes, which are derived from the neural crest, are unique in that they produce eu-/pheo-melanin pigments in unique membrane-bound organelles termed melanosomes, which can be divided into four stages depending on their degree of maturation. Pigmentation production is determined by three distinct elements: enzymes involved in melanin synthesis, proteins required for melanosome structure, and proteins required for their trafficking and distribution. Many genes are involved in regulating pigmentation at various levels, and mutations in many of them cause pigmentary disorders, which can be classified into three types: hyperpigmentation (including melasma), hypopigmentation (including oculocutaneous albinism [OCA]), and mixed hyper-/hypopigmentation (including dyschromatosis symmetrica hereditaria). We briefly review vitiligo as a representative of an acquired hypopigmentation disorder. PMID:24789876

  12. Etude experimentale des excitations topologiques de l'effet Hall quantique a nu = 1 dans les heterostructures semiconductrices a double puits quantique

    NASA Astrophysics Data System (ADS)

    Charlebois, Serge

    De nombreux travaux theoriques et experimentaux ont ete publies sur les excitations topologiques de gaz electroniques bidimensionnels (GE2D), appellees skyrmions, dans le regime de l'effet Hall quantique a remplissage unitaire. On attend des excitations semblables appellees bimerons dans les systemes formes de deux GE2D couples. Contrairement au cas des GE2D simples, aucune experience n'a, a notre connaissance, presente la mesure d'une propriete specifique aux bimerons. Nous presentons dans cette these des travaux experimentaux ayant pour objectif l'etude d'excitations topologiques dans les heterostructures a double puits quantique. Une manifestation attendue (les bimerons est la presence d'une anisotropie dans la conductivite a travers une constriction. Nous avons concu un dispositif original a point de contact a trois grilles non-coplanaires. Ce dispositif a trois grilles a la particularite de permettre la creation d'une constriction etroite dans le double GE2D tout en permettant l'equilibrage de la densite electronique entre les deux puits dans l'etroit canal de conduction. Nous avons fabrique ce dispositif de taille submicronique par electrolithographie sur des heterostructures a double puits. Les dispositifs ainsi fabriques ont ete etudies a basse temperature (0.3K) et ont montre un fonctionnement conforme aux attentes. Les travaux n'ont pas permis de mettre en evidence une anisotropie de transport revelatrice de l'existence de bimerons. Cette these est a notre connaissance la premiere etude experimentale visant la realisation de l'experience d'anisotropie de transport et est ainsi une contribution significative a l'avancement des connaissances dans ce domaine. Les travaux theoriques que nous presentons ont permis de montrer l'effet des excitations topologiques sur la capacite grille-GE2D du systeme. Ces travaux ouvrent la voie de la detection des bimerons par l'intermediaire de la mesure de la capacite grille-GE2D ou encore de la susceptibilite electrique du

  13. Analyse des transferts de chaleur et de masse transitoires dans un arena a l'aide de la methode zonale

    NASA Astrophysics Data System (ADS)

    Daoud, Ahmed

    Cette these presente les resultats d'une etude sur le mouvement de l'air et les transferts thermiques et massiques dans les arenas en regime transitoire et en 3D. Pour la partie aeraulique, il a ete question de developper un modele base sur la methode zonale qui permet de calculer les debits de l'air (dus a la ventilation et aux gradients de temperature) et de l'humidite entre les differentes zones du batiment et de determiner l'age de l'air dans chacune des zones. Pour la partie thermique, un modele de calcul du rayonnement entre les surfaces interieures du batiment qui a ete couple a TRNSYS afin de calculer sur une base annuelle les charges de chauffage et de refrigeration; ces dernieres tiennent compte des transferts radiatif et convectif, de la chaleur latente due a la condensation de l'humidite sur la glace et du surfacage. Le document presente est constitue de 7 chapitres qui peuvent etre resumes comme suit: Les chapitres 1, 2 et 3 sont consacres respectivement: a l'introduction generale, a la revue bibliographique et a la description du batiment modelise. Le chapitre 4 decrit l'approche developpee et la contribution importante qui y est apportee. Il presente l'utilisation de la methode zonale comme une alternative pratique aux methodes CFD car elle permet de realiser des simulations dynamiques sur une annee avec des temps de simulation tres courts et une precision acceptable. Il s'agit d'une approche intermediaire entre les modeles CFD et les modeles a un noeud d'air (considerant la temperature homogene dans un local). Le chapitre 5 est consacre a la methode de resolution numerique. L'outil de simulation a ete developpe en utilisant l'interface du logiciel TRNSYS: Le type 56 de ce logiciel a ete adopte comme modele energetique tandis que les autres modeles ont ete developpes et programmes en utilisant le logiciel MATLAB. Le chapitre 6 presente les resultats de simulation pour un arena sans faux plafond et avec un faux plafond et les resultats de mesures

  14. La place de la thoracoscopie dans la prise en charge des pathologies thoraciques: à propos de 104 cas

    PubMed Central

    Lakranbi, Marwane; Rabiou, Sani; Ghalimi, Jamal; Issoufou, Ibrahim; Ouadnouni, Yassine; Smahi, Mohamed

    2015-01-01

    Introduction La thoracoscopie est l'exploration endoscopique de la cavité pleurale, des organes avoisinants (diaphragme, péricarde, médiastin) et du poumon. Le but de ce travail se veut d'abord didactique; décrivant la thoracoscopie, ses techniques ainsi que sa place dans la prise en charge de la pathologie thoracique (indications et perspectives thérapeutiques) et informatif en rapportant l'expérience de notre équipe. Méthodes Il s'agit d'une étude rétrospective intéressant 104 thoracoscopies à visée diagnostique et/ou thérapeutique réalisées au service de chirurgie thoracique du Centre Hospitalier Universitaire Hassan II de Fès, sur une période de 04 ans (Août 2008-décembre 2012). Nous avons exclu de notre étude les cas ayant bénéficié d'une médiastinoscopie ainsi que les cas ayant bénéficié d'une thoracoscopie dans le cadre des traumatismes fermés du thorax ou des plaies thoraciques. Résultats L’ âge moyen des patients est de 47 ans, avec des extrêmes allant de 18 à 80 ans, et une légère prédominance masculine à 54%. La thoracoscopie est d'ordre pleural chez 86 patients, pulmonaire chez 10 patients et médiastinale chez 8 patients. La thoracoscopie avait une indication à visée diagnostique chez 87 cas et thérapeutique chez 52 patients (talcage dans 45 cas, décortication pleuropulmonaire dans 2 cas, résection de kystepleuro-péricardique dans 2 cas, cure de pneumothorax dans 2 cas et une fenêtre péricardique). L’évolution post opératoire etait marquée par une amélioration clinico-radiologique chez 40 malades, 11 ont présenté une amélioration clinique seule, 6 ont présenté une persistance ou une récidive de l’épanchement. Conclusion La thoracoscopie représente un réel gain en matière de diagnostic de certaines pathologies intra-thoraciques. Son intérêt thérapeutique limité doit être éventuellement étendu grâce à la chirurgie thoracique vidéo assistée, qui est une technique récente fiable

  15. Place de la chirurgie dans la prise en charge des cancers du sein chez la femme au Centre Hospitalier Universitaire Yalgado Ouedraogo: à propos de 81 cas

    PubMed Central

    Zongo, Nayi; Millogo-Traore, Timonga Françoise Danielle; Bagre, Sidpawalmdé Carine; Bagué, Abdoul-Halim; Ouangre, Edgar; Zida, Maurice; Bambara, Aboubacar; Bambara, Tozoula Augustin; Traoré, Si Simon

    2015-01-01

    Etudier la place de la chirurgie dans la prise en charge des cancers du sein au centre hospitalier universitaire Yalgado Ouédraogo. Nous avons réalisé une étude prospective et descriptive sur dix (10) mois portant sur la place de la chirurgie dans le cancer du sein. Elle a eu pour cadre les services de gynécologie-obstétrique et de chirurgie viscérale et digestive du centre hospitalier universitaire Yalgado Ouédraogo. Ont été pris en compte les indications, les gestes et les résultats de la chirurgie. Nous avons colligé 81 cancers mammaires. Le délai moyen de consultation a été de 14,26 mois. Les tumeurs T3 à T4 représentaient 82,71% des cas. Trente-huit patientes (46,91%) ont été opérées. La chimiothérapie néo adjuvante a été réalisée dans 29,63% des cas. Trente-quatre patientes (41,97%) étaient opérables d'emblée. Il s'agissait de mastectomie selon Madden dans 94,74% des cas et de chirurgie de propreté dans 2 cas (5,26% des cas). Une chimiothérapie adjuvante a été réalisée chez 52,63% des patientes opérées. Des complications à type de lymphocèle ont été notées dans 23,68% des cas. Leur traitement a consisté en des ponctions évacuatrices. Les indications de la chirurgie sont limitées par le retard diagnostique corollaire de stades avancés des cancers du sein. L'absence de la radiothérapie rend délicate la pratique de la chirurgie conservatrice et la mastectomie occupe toujours une place importante. Un diagnostic précoce permettrait d'augmenter les indications chirurgicales. PMID:26848364

  16. Urétéroscopie souple laser dans le traitement des calculs du haut appareil urinaire: résultats a propos de 166 interventions

    PubMed Central

    Padja, Essodina; Ibarra, Venceslas Amboulou; Lmezguidi, Khalid; Janane, Abdellatif; Ghadouane, Mohamed; Ameur, Ahmed; Abbar, Mohamed

    2015-01-01

    L’évolution de la technique opératoire fait de l'urétéroscopie souple –Laser (URSS-L) une méthode efficace et sure dans le traitement des calculs du haut appareil urinaire (HAU). Elle apparait comme une option salvatrice après échec des autres options thérapeutiques. Son coût limite son accessibilité et restreint ses indications dans certains contextes socio-économiques. Nous rapportons l'expérience du service sur les indications, les résultats et les complications de l'URSS-L dans le traitement des calculs du HAU. C'est une étude rétrospective sur 4ans concernant 130 patients ayant des calculs du HAU. Un scanner permettait de déterminer les caractéristiques des calculs avant l'intervention et de faire un contrôle après afin de juger de l'efficacité du traitement. Une analyse statistique évaluait l'influence des différents paramètres des calculs sur l'efficacité de l'intervention. Un suivi était réalisé afin de détecter les complications. L’âge moyen des patients était de 52 ± 17ans. 166 interventions étaient faites en 3 séries. Les indications étaient de première intention dans 50.32% suivi des échecs de LEC. La durée moyenne de l'intervention était de 73min ± 25min pour une taille moyenne des calculs de 13.78mm ± 5mm. Le taux de succès global était de 78.91% (78.71%; 80%; 100%) respectivement après la 1ère, la 2ème et la 3ème série. Aucun paramètre n'influençait significativement le taux de succès. 14.45% de complications était enregistré. L'URSS-L est une méthode aussi efficace que sure dans le traitement des calculs du HAU nous motivant malgré son coût, à élargir ses indications en première intention lorsque les calculs répondent aux critères de choix. PMID:26600912

  17. Revue systématique sur la contribution des femmes distributeurs communautaires dans la lutte contre l'onchocercose en Afrique sub-saharienne

    PubMed Central

    Vouking, Marius Zambou; Tadenfok, Carine Nouboudem; Evina, Christine Danielle; Nsangou, Moustapha; Bonono, Cécile-Renée; Yondo, David

    2014-01-01

    Le Programme Africain de lutte contre l'Onchocercose (APOC) fut lancé en 1995, comme complément au brillant programme de lutte contre l'onchocercose en Afrique de l'Ouest. En 2011, plus de 80 millions de personnes ont bénéficié de cette intervention grâce à la contribution de 268 718 Distributeurs Communautaires (DC). Ses résultats significatifs occultent le rôle des femmes DC dans cette lutte cette maladie. L'objectif de cette analyse est de déterminer la contribution des femmes DC dans le traitement de l'onchocercose sous directive communautaire en Afrique sub-saharienne, et d’évaluer leur acceptation dans ledit programme. Comme stratégie de recherche, nous avons identifié toutes les études pertinentes de Janvier 1995 à Décembre 2012. Des recherches ont été effectuées dans les bases de données suivantes: Medline, Embase (Excerpta Medica Database), CINAHL (Cumulative Index to Nursing and Allied Health Literature), LILAS (Latin American and Caribbean Literature on Health Sciences). Nous avons également consulté les sites d'APOC et de l'OMS AFRO. Deux auteurs ont indépendamment évalué la pertinence des articles potentiels à l'aide des critères d'inclusion et d'exclusion bien définis. Six (6) des 25 études ont rempli les critères d'inclusion. Une étude a montré que 81% des populations où il y avait des femmes DC ont reçu l'Ivermectine par rapport à 78% des villages où n'exerçaient pas de femmes DC. Une autre étude a montré qu'il y a eu une prise de conscience croissante dans les IDC en faveur de l'acceptation de la participation des femmes à la distribution communautaire de l'Ivermectine. De plus, 70% des membres de la communauté interrogés dans certaines zones endémiques, ont déclaré que les femmes étaient plus engagées, persuasives et plus patientes que les hommes dans la distribution de l'Ivermectine. Au terme de cette étude, les évaluations qui ont été effectuées donnent à penser que les femmes peuvent jouer

  18. Évaluation de l’implantation des services de première ligne en santé mentale jeunesse dans Lanaudière

    PubMed Central

    Richard, Caroline; Poissant, Céline; Gil, Michel

    2012-01-01

    Résumé Objectif: La province de Québec a amorcé une vaste réforme des services en santé mentale jeunesse. Cette étude visait à évaluer la première année d’implantation de ces services de première ligne dans les deux réseaux locaux de services (RLS) de Lanaudière. Méthodologie: Une évaluation qualitative de type formatif et participatif a été réalisée. La collecte des données a été menée auprès de 32 principaux acteurs engagés dans la mise en œuvre de ces services ou ayant pris part au processus décisionnel. Cinq entrevues semi-directives de groupe ont été effectuées avec les comités et les équipes concernés. L’information colligée a fait l’objet d’une analyse de contenu qualitative descriptive. Résultats: L’implantation des services de première ligne en santé mentale jeunesse dans la région de Lanaudière a entraîné une mobilisation des partenaires. Celle-ci a été identifiée par l’ensemble des acteurs comme une condition favorable à l’implantation de ces services. La décision de poursuivre l’implantation malgré la pénurie de pédopsychiatres a renforcé la détermination et l’engagement des acteurs. Par contre, le manque de ressources humaines, l’insuffisance de médecins et les difficultés d’articulation des services de première ligne avec la pédopsychiatrie ont constitué des obstacles à l’implantation de ces services. Conclusion: Malgré certaines difficultés et différences entre les réseaux locaux de services dans la mise en œuvre des services de première ligne en santé mentale jeunesse, celle-ci semble avoir provoqué une évolution des cultures institutionnelle et clinique dans Lanaudière. PMID:22548104

  19. VITILIGO AND THE MELANOCYTE RESERVOIR

    PubMed Central

    Falabella, Rafael

    2009-01-01

    Repigmentation of vitiligo depends on available melanocytes from three possible sources: from the hair follicle unit which is the main provider of pigment cells, from the border of vitiligo lesions, and from unaffected melanocytes within depigmented areas; pigment cells at these locations originate a perifollicular, border spreading and a diffuse repigmentation pattern. In order for repigmentation to take place under stimulation with diverse therapies, melanocytes should be present in appropriate numbers. Melanocyte tissue stem cells located in the niche at the bulge region of the hair follicle are the most important sources for providing immature pigment cells that undergo terminal differentiation and originate repigmentation, but cytokines, UVR and other molecules acting in melanogenesis with adequate regulation mechanisms contribute to successful recovery in vitiligo. The presence of keratinocyte stem cells in the interfollicular epidermis raises the question on the possibility of melanocyte stem cells in a similar location and the development of future strategies for therapeutic purposes. PMID:20101329

  20. Caractérisation des effets de l'implantation ionique dans les alliages super-élastiques nickel titane par diffraction des rayons X

    NASA Astrophysics Data System (ADS)

    Pelletier, H.; Muller, D.; Grob, J. J.; Mille, P.; Cornet, A.

    2002-07-01

    the specific properties (shape memory effect and super-elasticity) of NiTi alloys have provided the enabling technology for many groundbreaking applications in the medical and dentistry industries. These applications include everything from the surgical tools to permanent implants. Super-elastic NiTi alloys take advantage of a stress induced martensitic transformation to achieve incredible amounts of flexibility. This last property represents the most interesting aspect of such alloys for restoration procedures. However, recent instrumentation tests have shown brittle rupture of endodontic instruments inside the tooth during preparation of dental root channels.To improve the mechanical properties of NiTi endodontic instruments, argon, nitrogen and boron implantations at different energies and at fixed dose (1.10^{17} at.cm^{-2}) have been used. In this paper, we have investigated the effects on NiTi microstructure, especially the crystalline to amorphous transition induced by ion bombardment, using Grazing Incidence X-ray Diffraction (GIXRD). Nano-indentation tests have also been performed to determine hardness H and elastic modulus E of implanted surfaces as a function of ion species and energy. Le but de cette d'étude est de caractériser les effets de l'implantation ionique sur la microstructure d'un alliage Nickel Titane à l'aide de la diffraction des rayons X en incidence rasante. Nous avons réalisé différents types d'implantation en faisant varier l'espèce implantée (bore, azote, argon) ainsi que l'énergie d'implantation, pour des doses d'implantation de l'ordre de 1.10^{17} at.cm^{-2}. Les résultats des mesures de diffraction sous différents angles d'incidence (0{,}5^circ leq α_ileq 6^circ) ont été corrélés avec les différents profils d'implantation simulés. Des tests de nanoindentation ainsi que des mesures de RBS ont été également réalisés. Après implantation, on observe la formation d'une couche amorphe, conduisant à une

  1. Charges convectées par écoulements laminaires et turbulents dans des tubes de section rectangulaire

    NASA Astrophysics Data System (ADS)

    Touchard, G.; Dominguez, G.; Madani, K.

    1991-07-01

    This study relates the phenomenon of streaming currents by flow in a pipe of rectangular cross section. We compute at first the velocity profile in the case of a laminar flow. Then with the assumption of a weak space charge density an analytical solution for the space charge density profile in such pipe and for that kind of flow is also obtained. Thus we give the expression of the space charge density convected by a laminar flow. In the case of a turbulent flow the space charge convected is computed in the case of two parallel walls. At least, the experimental conditions and the confrontation between experiments and theoretical predictions are presented. Dans cette étude, nous analysons le phénomène de transport de charges électriques par convection dans un tube de section rectangulaire. Il nous faut tout d'abord définir le champ des vitesses hydrodynamiques. Dans le cas laminaire, une solution analytique peut être obtenue, aussi bien pour la vitesse que pour la densité volumique de charge en faisant l'hypothèse des faibles densités. A partir de ces résultats, nous calculons alors la densité volumique de charge transportée par un écoulement laminaire. Dans le cas d'un écoulement turbulent, la complexité du phénomène aussi bien hydrodynamique que d'électrisation, nous oblige à nous ramener au cas monodimensionnel de deux plans parallèles. Une expression de la vitesse moyenne axiale et de la vitesse fluctuante transversale est proposée ainsi qu'une modélisation de la nouvelle répartition de la charge. Les courants d'écoulement en turbulent peuvent alors être calculés. Nous présentons ensuite les conditions expérimentales ainsi qu'une confrontation entre les expériences réalisées en écoulement laminaire et turbulent avec les prévisions théoriques.

  2. Le risque de détresse morale dans la pratique contemporaine des soins de santé.

    PubMed

    Austin, Wendy

    2016-05-01

    Les professionnels de la santé sont des agents moraux dont la relation fiduciaire avec le public est animée par la responsabilité et la promesse de puiser dans leurs connaissances et leurs habiletés pour aider les personnes sous leurs soins. Lorsque leur capacité à tenir cette promesse est freinée ou compromise, ils risquent de souffrir de détresse morale. Le concept de détresse morale est défini et mis en contexte dans le milieu de la santé. Les contraintes et les facteurs qui en sont à l'origine sont présentés, de même que les moyens utilisés par les professionnels de la santé et les organisations de santé pour la soulager. Un changement transformateur s'impose pour vaincre la culture du silence et maintenir un système de santé où il est possible de vivre avec sa conscience. PMID:27068874

  3. La place du traitement non opératoire des contusions abdominales dans les pays en voie de développement

    PubMed Central

    Rabbani, Khalid; Narjis, Youssef; Louzi, Abdelouahed; Benelkhaiat, Redouane; Finech, Benacer

    2015-01-01

    Le traitement non opératoire des contusions de l'abdomen représente une approche thérapeutique nouvelle des traumatismes fermés de l'abdomen. La disponibilité d'un plateau technique performant constitue classiquement une des principales conditions pour la réussite de cette attitude. Nous essayons d’étudier les différents aspects épidémiologiques, diagnostiques et thérapeutiques de cette affection dans le contexte d'un pays en voie de développement, à travers les résultats d'une série de 106 malades. une série de 106 patients est prise en charge par le traitement non opératoire. La gravité des lésions est appréciée par les données cliniques et paracliniques, ainsi que la morbidité et la mortalité sont analysées. les accidents de la circulation étaient la première cause des contusions abdominales, dans notre contexte. Les lésions hépatiques étaient les plus fréquentes (65% des cas), suivit des lésions spléniques chez 19 patients. La notion de polytraumatisme était très fréquente. La durée moyenne de surveillance était de 9,5 jours. Seize malades étaient transfusés, et le nombre moyen de culots globulaires (CG) était de 3,5 culots par patient. Une laparotomie en urgence était indiquée chez 10 patients (9.4%) devant l'instabilité hémodynamique. Trois malades ont nécessité un traitement chirurgical secondaire. On avait noté un taux de mortalité de 3.7% soit 4 cas. il semble à partir de notre expérience que l'abstention chirurgicale peut constituer, dans des conditions strictes de surveillance, une alternative thérapeutique de référence dans les pays en voie de développement, sûre et justifiée à une chirurgie d'urgence toujours difficile. PMID:26097636

  4. Mesure de la Polarisation des Lambda Produits dans les Collisions Positron-Electron AU Lep a L'aide du Detecteur Opal

    NASA Astrophysics Data System (ADS)

    Vandenplas, Denis

    Le Modele Standard est le cadre theorique general qui, jusqu'a present, a permis l'interpretation de tous les resultats experimentaux en physique des hautes energies. Cette theorie decrit, entre autres, la production d'une paire de particules elementaires, formee d'un quark et d'un antiquark, a partir de la desintegration de l'un des bosons mediateurs de l'interaction faible, le Z^0. Cependant, dans ce cas precis, la transformation subsequente des quarks primaires en particules reelles, un processus appele hadronisation, n'est decrite qu'a l'aide de modeles phenomenologiques. Afin de sonder les mecanismes de l'hadronisation, cette these presente la mesure du transfert du spin d'un quark etrange primaire a une particule appelee Lambda lors des desintegrations hadroniques du Z^0. L'etude a ete realisee dans le cadre de la collaboration OPAL, une des quatre experiences menees au collisionneur LEP, la ou des electrons et des positrons sont acceleres jusqu'a une energie commune, sqrt{s} = {rm E_ {cm}}, voisine de l'energie de production du rm Z^0, M_{Z ^0} egale a 91.3 GeV. La theorie electrofaible precise la direction du spin, c'est-a-dire la polarisation, d'un quark etrange primaire provenant de la desintegration d'un Z ^0. Quant a lui, le modele des quarks etablit que l'orientation du spin d'un Lambda est directement reliee a la polarisation du quark etrange dont il provient. La question est de determiner dans quelle mesure la polarisation du quark primaire est transmise au Lambda a la suite du processus de l'hadronisation, decrit dans le cadre de la ChromoDynamique Quantique. Une estimation, qui tient compte de tous ces differents aspects theoriques, evalue a 30% la polarisation des Lambda dont l'impulsion est superieure a 15 GeV/c. La mesure experimentale de la polarisation repose sur l'identification des Lambda a partir de la reconstitution de la desintegration Lambdato ppi^-. Ce processus, qui se deroule par le biais de l'interaction faible, viole la parite car

  5. Genetics Home Reference: giant congenital melanocytic nevus

    MedlinePlus

    ... noncancerous skin patch (nevus) that is composed of pigment-producing cells called melanocytes . It is present from ... called neurocutaneous melanosis, which is the presence of pigment-producing skin cells (melanocytes) in the tissue that ...

  6. Profil épidémiologique des fibromes utérins dans la région de Sidi Bel Abbes, Algérie

    PubMed Central

    Chalal, Nourelhouda; Demmouche, Abbassia

    2013-01-01

    Introduction Les léiomyomes ou fibromyomes plus communément dénommés fibromes, sont les tumeurs les plus répandues du tractus génital féminin. Ils affectent 20 à 25% des femmes en activité génitale. Notre étude vise à élucider la réalité de ce type de pathologie dans la région de sidi bel Abbes, nord-ouest d'Algérie. Méthodes A travers une étude rétrospective allant du 1er janvier 2008 au 1 mai 2011 portant sur les patientes opérées pour fibrome au sein de la maternité de Sidi Bel Abbes, nous avons relevé les particularités épidémiologiques et cliniques de cette pathologie. Résultats Au total 323 cas de fibromes ont été recensés. La tranche d'âge la plus touchée varie de 40 à 44 ans dans une fourchette d'âge comprise entre 20 et 74 ans. 37.83% des patientes étaient nullipares. Une prédominance des patientes dont l'âge de la ménarche est précoce, a été retenue (60.3%). 3% des femmes ont présenté un terrain familial prédisposant. La symptomatologie était dominée par les hémorragies génitales (35%). La majorité des patientes (51.70%) présentaient un utérus polymyomateux dont la localisation des fibromes était principalement corporéale (96%), sous séreuse (43%). Le traitement était conservateur dans 71.82% des cas. Conclusion Sur la base des résultats obtenus, la mise au point d'un programme national de sensibilisation et de dépistage précoce, s'impose PMID:23847704

  7. Formation et Evolution des Structures dans le Milieu interstellaire. Une Approche théorique, numérique et observationnelle

    NASA Astrophysics Data System (ADS)

    Hennebelle, Patrick

    2000-11-01

    Le milieu interstellaire, au sein duquel se forme les étoiles,présente d'importants contrastes de densités. Ces structures se forment sous l'action couplée de processus magnétohydrodynamiques, thermiques et chimiques. La première partie de cette thèse est un travail théorique et numérique sur la condensation induite dynamiquement de gaz chaud et diffus en une phase froide et condensée. Nous montrons, tout d'aborddans le cas hydrodynamique, puis MHD, comment, dans un milieu thermiquement bistable, une fluctuation de vitesse typiquement transonique conduit, si elle est d'amplitude suffisante et dure un temps assez long, à la formationd'une structure stable. L'influence de divers paramètres -amplitude et échelle spatiale caractéristique de la perturbation, pression initiale, configuration du champ magnétique- sur la condensationest étudiée numériquement et analytiquement. Des spectres synthétiques sont calculés et qualitativement comparés aux spectres observationnels. La seconde partie de la thèse porte sur l'étudeobservationnelle des phases les plus condensées du milieu interstellaire détectées en absorption sur le fond infrarouge galactique par le satellite ISO. Nous effectuons tout d'abordune extraction systématique de ces objets à partir d'une analyse multi-échelle des données ISOGAL.L'étude du rapport des contrastes à 7 et 15 um permet de mesurer le rapport de l'extinction interstellaire, peu connue dans cette région du spectre, à ces deux longueurs d'onde. Des estimations d'opacité de quelques objets sont égalementdéduites des données en infrarouge. Des observations complémentaires spectroscopiques et bolométriques dans le domaineradio ont été effectuées et permettent une analyse plus détaillée des paramètres physico-chimiques de ces nuages.

  8. Technique de Blount dans le traitement des fractures supra condyliennes du coude chez l'enfant: à propos de 68 cas

    PubMed Central

    Chagou, Aniss; Rhanim, Abdelkarim; Zanati, Rachid; Kharmaz, Mohammed; Lamrani, Moulay Omar; Berrada, Mohammed Saleh; El Yaacoubi, Moradh; Ettaybi, Fouad

    2014-01-01

    La fracture de la palette humérale est la plus fréquente des fractures du coude de l'enfant. La méthode de BLOUNT, constitue une perspective thérapeutique longtemps connue. Elle consiste en une réduction sous contrôle scopique de la fracture et une contention en hyper flexion du coude. Notre série a porté sur l’étude de 68 cas de fractures supra condyliennes chez des enfants traités dans le service des urgences chirurgicales pédiatriques de l'hôpital d'enfant de Rabat entre janvier 2009 et janvier 2012. Nous comparons nos résultats avec les données de la littérature. PMID:25667714

  9. La Trypanosomose Humaine Africaine dans l’espace ivoiro-burkinabé : optimisation des stratégies de surveillance épidémiologique

    PubMed Central

    Kambiré, R.; Lingué, K.; Courtin, F.; Sidibé, I.; Kiendrébéogo, D.; N’gouan, K.E.; blé, L.; Kaba, D.; Koffi, M.; Solano, P.; Bucheton, B.; Jamonneau, V.

    2012-01-01

    L’objectif de cet article est de décrire les récentes données de surveillance médicale de la Trypanosomose Humaine Africaine (THA) au Burkina Faso et en Côte d’Ivoire afin (i) de dresser un bilan de la situation actuelle de la maladie dans ces deux pays qui entretiennent depuis plus d’un siècle des liens migratoires, économiques et épidémiologiques intimes et (ii) de définir les stratégies à mettre en place dans l’objectif d’une élimination durable. Les résultats de la surveillance active et passive ont montré que les trypanosomés dépistés au Burkina-Faso ces dernières années sont tous des cas importés provenant de Côte d’Ivoire. Cependant, la réintroduction du parasite est effective et le risque d’une reprise de la transmission existe. En Côte d’Ivoire, plusieurs foyers “historiques” toujours endémiques font craindre des phénomènes de réémergence et de propagation. Dans l’objectif d’une élimination durable de la THA dans ces deux pays, les acteurs de la lutte doivent adapter leur système de surveillance en fonction des différents contextes épidémiologiques. Les prévalences actuelles ne justifient plus, excepté des cas particuliers, l’usage systématique et très onéreux du dépistage actif par prospections médicales exhaustives. Elles tendent plutôt à privilégier des systèmes intégrés aux systèmes de santé nationaux et utiliser des méthodes permettant de cibler les zones prioritaires d’intervention à partir notamment d’un échange d’informations épidémiologiques entre les deux pays. Pour accompagner le processus d’élimination durable, les acteurs de la recherche doivent étudier le rôle respectif des réservoirs humain et animal dans le maintien de la transmission, participer au suivi sur le long terme des cas traités et des suspects sérologiques, et évaluer en termes de coût/efficacité les stratégies mises en place par les Programmes Nationaux afin de les optimiser. PMID

  10. Coût clinique des retards dans le changement de traitement

    PubMed Central

    Walmsley, Sharon

    2007-01-01

    La prise en charge des patients séropositifs pour le VIH ayant déjà reçu un traitement continue de s’améliorer et d’évoluer. Les nouvelles lignes directrices semblent indiquer que l’objectif du traitement devrait être une suppression virologique maximale. La meilleure façon d’y parvenir consiste à utiliser une combinaison d’agents auxquels le virus sera le plus vraisemblablement sensible et, si possible, des agents appartenant à une nouvelle classe thérapeutique. Les cas discutés démontrent comment l’utilisation d’un schéma thérapeutique puissant à titre de traitement de sauvetage peut avoir de bons résultats virologiques, immunologiques et cliniques. Toutefois, si le traitement de sauvetage retenu n’est pas assez puissant pour atteindre ces objectifs, la durabilité de la réponse est limitée. Ce qu’il faut retenir ici, c’est que ces stratégies devraient reposer sur la puissance du schéma thérapeutique et qu’il ne faut pas retarder l’instauration des agents en cas d’échec d’une stratégie.

  11. La physique des tas de sable Description phénoménologique de la propagation des contraintes dans les matériaux granulaires

    NASA Astrophysics Data System (ADS)

    Claudin, Ph.

    This work deals with the stress distribution in dry granular media such as sand. As a matter of fact, the granular family is amazingly wide: raw materials used in building, chemical or food industries are made of little grains. Predicting how forces propagate and fluctuate into granular media is then a real and concrete challenge. This goal is not easy to reach. One reason is that the stress distribution is strongly inhomogeneous: the forces applied on a granular system will be supported almost entirely by a fraction of the grains which form chains, or arches. As a consequence, the stress profile beneath a sandpile depends on the way that the pile was built. In order to describe quantitatively these effects, we proposed a phenomenological friction relation between arches. The differential equations which come out from this modelling are of hyperbolic type, which means that there exists particular lines for propagation called characteristics. We managed to match these characteristics with arches. These models fit well with experimental data, and can explain for example the dip of pressure observed beneath the apex of a pile made with a hopper. They also significantly improve Janssen's predictions for the silo. We also looked at stress fluctuations, and showed that granular material are intrinsically fragile when subjected to changing external forces or perturbations. This property has been particulary studied within a scalar arching model with which we were able to visualize changes of stress paths and subsequent changes of the stress distribution. Ce travail porte sur la description de la manière dont les forces se propagent dans les milieux granulaires comme le sable. Cette catégorie de matériaux est en fait très vaste, et pouvoir prédire de manière satisfaisante la répartition des contraintes au sein d'un système granulaire est un enjeu industriel réel et concret. Or ceci est difficile. Une des raisons en est que cette répartition est très inhomog

  12. La greffe de peau totale dans le traitement des séquelles de brûlures de la main et des doigts: A propos de 84 cas

    PubMed Central

    Boukind, S.; Droussi, H.; Elatiqi, O.K.; Dlimi, M.; Dhaidah, O.; Ejjiyar, M.; Quaboul, M.; Dehhaze, A.; Fkhar, S.; Elamrani, D.; Benchamkha, Y.; Ettalbi, S.

    2014-01-01

    Summary Nous avons mené une étude rétrospective s’étendant de septembre 2004 à septembre 2012 sur les données de à propos de 84 patients présentant des séquelles de brûlure majeures de la main. Ces patients étaient traités chirurgicalement par une greffe de peau totale. Le but de cette étude est, donc, d’insister sur la simplicité de cette technique et surtout son efficacité et sa fiabilité. L’âge moyen de la survenue de la brûlure était de 4 ans. L’âge moyen de nos patients était de 18,3 ans (2-62 ans), avec prédominance masculine dans 60% des cas. L’agent causal le plus fréquent était un agent thermique - le plus souvent un liquide chaud (56%). Le délai moyen entre la fin de la cicatrisation et la prise en charge des séquelles était de 36 mois (2 mois - 16 ans). Dans 69 cas (82.5%), les lésions étaient localisées au niveau de la face palmaire de la main. Les séquelles ont été dominées par les rétractions digitales (65%) dont le déficit fonctionnel est évident. Une greffe de peau totale a été réalisée chez tous nos patients après libération des brides et excision des placards cicatriciels. Les rétractions commissurales ont été traitées par des plasties en Z. Dans 95% des cas, le prélèvement de peau totale était réalisé au niveau du pli inguinal. Le recul moyen était de 5,5 ans (1-8 ans). 11 patients ont été perdus de vu. Les résultats après cicatrisation complète et rééducation ont été jugés satisfaisants (bons) dans 62 cas (85%), et assez bons dans 11 cas (15%). Un traitement initial bien conduit et effectué dans les meilleures conditions permet non seulement de réduire le nombre de séquelles des brûlures mais encore de les rendre moins sévères. PMID:26336368

  13. Aspects histo-épidémiologiques des cancers génitaux de la femme dans la région du Littoral, Cameroun

    PubMed Central

    Engbang, Jean Paul Ndamba; Koh, Valère Mve; Tchente, Charlotte Nguefack; Fewou, Amadou

    2015-01-01

    Décrire les caractéristiques épidémiologiques et histopathologiques des tumeurs malignes génitales de la femme dans la région du littoral du Cameroun. Il s'agissait d'une étude rétrospective descriptive et analytique portant sur les cancers des organes génitaux de la femme, histologiquement prouvés pendant une période de 10 ans (2004-2013), répertoriés dans les registres des trois laboratoires d'anatomopathologie de la région (Hôpital Laquintinie de Douala, Hôpital Général de Douala, laboratoire Anapathos) et des services d'oncologie de ces hôpitaux. Les variables étudiées étaient: la fréquence, l’âge, le sexe, la localisation de la tumeur et le type histopathologique. Au total, 802 cas de cancers génitaux de la femme ont été recensés, soit une fréquence annuelle de 80,2 cas en moyenne. Le col utérin avec 580 cas (72,32%) a été la localisation la plus fréquente; suivi de l'endomètre (corps utérin) avec 93 cas (11,60%), puis des ovaires 91 cas (11,35%). L’âge moyen des patientes était de 50, 30±12,67 ans, avec les extrêmes allant de 14 à 85 ans. Selon le type histologique, les tumeurs épithéliales ont été les plus fréquemment rencontrées, soit 758 patientes (94,51%), les lymphomes venaient en seconde position avec 29 cas (3, 62%), les autres variétés histologiques (sarcomes, tumeurs germinales, tumeurs du mésenchyme et du cordon) représentant moins chacune de 1%. Les tumeurs malignes des organes génitaux féminins sont fréquentes dans la région du littoral du Cameroun, elles sont dominées essentiellement par le cancer du col utérin. Les tumeurs épithéliales sont le type histologique le plus fréquent. PMID:26327953

  14. Evaluation du niveau de connaissance des patients sur la gestion du traitement par les antis vitamines K dans le service de cardiologie de Ouagadougou

    PubMed Central

    Samadoulougou, André; Temoua Naibe, Dangwé; Mandi, Germain; Yameogo, Relwendé Aristide; Kabore, Elisé; Millogo, Georges; Yameogo, Nobila Valentin; Kologo, Jonas Koudougou; Thiam/Tall, Anna; Toguyeni, Boubacar Jean Yves; Zabsonre, Patrice

    2014-01-01

    Introduction Les antivitamines K (AVK), traitement anticoagulant oral le plus largement prescrit, posent un réel problème de santé publique du fait de leur risque iatrogène. L'objectif de cette étude était de préciser le niveau de connaissance des patients sur la gestion de leur traitement par les AVK. Méthodes Il s'est agi d'une enquête transversale descriptive réalisée au CHU-Yalgado Ouédraogo, sur une période de 03 mois : du 1er mars au 31 mai 2012. Un questionnaire a été administré aux patients bénéficiant d'un traitement AVK depuis au moins un mois. Résultats Soixante-dix patients ont été inclus dans l'étude dont 30 hommes. L'âge moyen était de 49 ans ± 16 ans. Les cardiopathies et la maladie thromboembolique veineuse justifiant l'institution du traitement AVK étaient retrouvées respectivement dans 58,6% et 41,4% des cas. Le nom de l'AVK et la raison exacte du traitement étaient connus respectivement dans 91,4% et 67,1% des cas. Plus de la moitié des patients (68,6%) savaient que les AVK rendaient le sang plus fluide. Quarante-six patients (65,7%) citaient l'INR comme examen biologique de surveillance du traitement et seulement 28 patients (40%) connaissaient les valeurs cibles. La majorité des patients ne connaissait pas les risques encourus en cas de surdosage (72,8%) et de sous-dosage (71,4%). Une automédication par anti-inflammatoire non stéroïdien était signalée par 18 patients (25,7%). Les choux (74,3%) et la laitue (62,9%), aliments à consommer avec modération, étaient les plus cités. Conclusion Les connaissances des patients sur la gestion des AVK étaient fragmentaires et insuffisantes pour assurer la sécurité et l'efficacité du traitement. La création d'un programme d'éducation thérapeutique sur les AVK s'avère alors nécessaire. PMID:25870741

  15. Sorafenib induced eruptive melanocytic lesions.

    PubMed

    Uhlenhake, Elizabeth E; Watson, Alice C; Aronson, Peter

    2013-05-01

    Sorafenib is a multikinase inhibitor FDA-approved for the treatment of advanced renal cell and hepatocellular carcinoma. Dermatologic side effects include hand-foot skin reaction, facial and scalp erythema and desquamation, splinter subungual hemorrhages, alopecia, pruritus, xerosis, keratoacanthomas, and squamous cell carcinomas. We report sudden eruption of melanocytic nevi diffusely in a patient receiving sorafenib. PMID:24011281

  16. Étude ethnobotanique des plantes utilisées dans le traitement du diabète dans la médecine traditionnelle de la région Maritime du Togo

    PubMed Central

    Holaly, Gbekley Efui; Simplice, Karou Damintoti; Charlemagne, Gnoula; Kodjovi, Agbodeka; Kokou, Anani; Tchadjobo, Tchacondo; Amegnona, Agbonon; Komlan, Batawila; Jacques, Simpore

    2015-01-01

    Introduction Les plantes constituent une grande source de principes actifs qui peuvent être utilisés pour traiter de nombreuses maladies, dont le diabète. L'objectif de cette étude était de recenser les plantes utilisées en médecine traditionnelle pour traiter le diabète dans la région Maritime du Togo. Méthodes De janvier 2013 à juin 2014, une enquête ethnobotanique a été réalisée auprès de 164 guérisseurs traditionnels dans la région Maritime par des interviews directes à l'aide d'un questionnaire semi structuré. Résultats Les données recueillies ont permis d'identifier 112 espèces végétales appartenant à 51 familles. Les familles les plus représentées ont été les Caesalpiniaceae / Fabaceae avec 9 espèces, suivie des Euphorbiaceae et des Compositae avec 8 espèces chacune. Les espèces les plus citées ont été Allium sativum, Alium cepa, Guilandina bonduc, Moringa oleifera et de Picralima nitida qui ont eu une valeur usuelle de 0,05. En termes de recettes, 132 recettes sont préparées à partir des 112 espèces de plantes. Les recettes à plantes uniques ont été au nombre de 78, tandis que 54 recettes sont obtenues par des associations de plantes. Les parties de plantes les plus utilisées ont été les feuilles suivies par les racines. La principale méthode de préparation reste la décoction. Conclusion La région maritime du Togo dispose d'une biodiversité floristique importante en matière de plantes antidiabétiques. Ces résultats constituent une bonne base de données pour le criblage biologique dans la recherche de molécules antidiabétiques à base des plantes. PMID:26309469

  17. Formes hémorragiques de Dengue observées dans le service des maladies infectieuses du CHU Yalgado Ouédraogo, Burkina Faso

    PubMed Central

    Mamoudou, Savadogo; Boushab, Boushab Mohamed

    2016-01-01

    La dengue est une arbovirose ré émergente dans les pays tropicaux. Sa forme hémorragique peut s'accompagner d'une défaillance circulatoire pouvant conduire à un choc hypovolémique, souvent fatal. Nous rapportons une série de trois cas de formes hémorragiques de dengue observées dans le service des maladies infectieuses du CHU Yalgado Ouédraogo de Ouagadougou dont l'objectif est de décrire les caractéristiques épidémiologiques cliniques et évolutives. Les cas étaient des jeunes de sexe féminin dont l’âge variait entre 27 ans et 43 ans, résidant dans la ville de Ouagadougou. Malgré de multiples transfusions de concentrées plaquettaires et un traitement symptomatique, nous déplorons un cas de décès. Le développement d'antiviraux et la mise au point de nouveaux vaccins constituent une lueur d'espoir pour prévenir la létalité due à cette maladie. PMID:27303584

  18. Profil épidémiologique des femmes enceintes cardiaques dans le centre de maternité de Tunis: expérience du service A

    PubMed Central

    Khemiri, Khaled; Jenayah, Amel Achour; Boudaya, Fethia; Hamdi, Asma; Meskhi, Souad; Sfar, Ezzeddine; Chelli, Dalenda

    2015-01-01

    Nous rapportons dans ce travail, le profil épidémiologique des femmes enceintes porteuses d'une cardiopathie ayant accouché dans le service «A» du centre de maternité de Tunis. Il s'agit d'une étude rétrospective descriptive sur 3 ans, de janvier 2010 à décembre 2012, portant sur les dossiers des parturientes cardiaques suivies et ayant accouché dans notre service, à l'exclusion des cardiopathies hypertensives. Les paramètres analysés étaient la gestité et parité des parturientes, le type de la cardiopathie, le mode d'accouchement et le pronostic foetal. Cinquante six cas sur 19655 accouchements avaient été recrutés, soit une incidence de 1 pour 351 accouchements (0,285%). L’âge moyen de nos parturientes était de 30,89±5,3 ans avec des extrêmes allant de 21 à 42 ans. 23 (41,07%) avaient une cardiopathie congénitale, 35 (62,5%) une valvulopathie, 6 (10,71%) un trouble du rythme, 3 (5,35%) un trouble de la conduction à type de bloc auriculo-ventriculaire et 3 (5,35%) une cardiopathie ischémique. Cinquante deux parturientes (92,85%) avaient accouché à un terme dépassant les 37 semaines d'aménorrhée (SA). L'accouchement s'est déroulé par les voies naturelles chez 22 (39,28%) patientes et par césarienne chez 34 (60,71%). Le poids moyen des nouveaux nés à la naissance était de 3341,25 grammes. 3 transferts néonataux en unité de réanimation étaient réalisés avec un seul cas de décès néonatal. La grossesse et l'accouchement chez la femme cardiaque constituent un haut risque materno-foetal dépendant du type, mais surtout du stade de la cardiopathie, nécessitant une prise en charge précoce et multidisciplinaire de la parturiente. PMID:26327977

  19. Conception d'un capteur intelligent pour la détection des vapeurs de styrène dans l'industrie

    NASA Astrophysics Data System (ADS)

    Agbossou, Kodjo; Agbebavi, T. James; Koffi, Demagna; Elhiri, Mohammed

    1994-10-01

    The techniques of measurement of toxic gases are nowadays based on the semiconductor type sensors. The modelling and the electronic processing of their signals can be used to improve the accuracy and the efficiency of the measurement. In this paper, an intelligent system using a semiconductor sensor has been designed for the detection of the styrene vapors. A set of the environmental parameters sensors such as the temperature, the pressure and the humidity, is added to the basic sensor and allows a precise detection of the styrene vapors in air. A microcontroller and a communication interface, that are included in the control system and in the data processing system, provide the local intelligence. The linearization routines of the differents sensors are in the memory of the microcontroller. The system made of the sensors, of the amplification circuits, of the microcontroller and of the communication network between the smart sensor and the computer is analysed. A laboratory test of the device is presented and the accuracies and efficiencies of the differents sensors are given. Les techniques fiables de quantification des gaz polluants sont aujourd'hui basées sur l'utilisation des détecteurs à récepteurs chimiques et sur des capteurs à semiconducteurs. La modélisation et le traitement numérique des signaux résultants sont importants pour une mesure efficace et précise dans un milieu donné. Dans cet article, un capteur intelligent, utilisant un détecteur de gaz type semiconducteur a été réalisé pour la détection des vapeurs de styrène. Un ensemble de détecteurs des paramètres environnementaux, tels que la température, la pression et l'humidité, ajoutés au capteur de styrène, permettent de mesurer avec un bon contrôle les vapeurs de styrène dans l'air. Le système de contrôle et de gestion local des données est constitué d'un microcontrôleur et d'une interface de communication. Le microcontrôleur contient dans sa mémoire toutes les

  20. Evaluation de la sécurité du circuit des médicaments anticancéreux dans un hôpital régional en Tunisie

    PubMed Central

    Sahli, Jihène; El Ghardallou, Meriam; Bougmiza, Iheb; Henchiri, Besma; Limam, Manel; Mejdoub, Rim; Mtiraoui, Ali; Ajmi, Thouraya

    2016-01-01

    Introduction Parmi les événements indésirables, ceux liés au circuit des médicaments occupent une place importante et risquent de causer un préjudice grave aux patients. Dans ce contexte, nous avons mené cette étude dans l'optique de décrire et d’évaluer le circuit des médicaments anticancéreux dans un hôpital régional tunisien. Méthodes Il s'agit d'une étude évaluative du risque lié aux médicaments anticancéreux, type « visite de risque » menée sur une période de 15 jours au cours de l'année 2014 au service de cancérologie de l'hôpital régional de Gafsa (Tunisie). Cette méthode d’évaluation est inspirée de celle conduite par le projet « SECURIMED » développé par le Comité de Coordination de l'Evaluation Clinique et de la Qualité en Aquitaine (CCECQA), en France. Résultats Dans notre étude, l'observation du circuit des médicaments anticancéreux a révélé certaines insuffisances. On a noté que la répartition des missions des différents acteurs est sujette parfois à des glissements de tâches. Un manque important ainsi que une inadéquation aux normes au niveau des équipements nécessaires pour la préparation et la protection des professionnels manipulant ces médicaments ont été également décelés. Conclusion La sécurisation du circuit des médicaments devrait être une priorité inscrite dans l'ensemble des démarches nationales et partagée par tous les intervenants et ce dans l'optique d'atteindre un objectif prémium: la qualité de la prise en charge globale et la sécurité des patients. PMID:27200135

  1. Commerce de detail de l'essence automobile: Modelisation de l'impact a court terme des facteurs endogenes et exogenes sur les ventes d'essence dans les stations-service a Montreal

    NASA Astrophysics Data System (ADS)

    Nguimbus, Raphael

    La determination de l'impact des facteurs sous controle et hors controle qui influencent les volumes de vente des magasins de detail qui vendent des produits homogenes et fortement substituables constitue le coeur de cette these. Il s'agit d'estimer un ensemble de coefficients stables et asymtotiquement efficaces non correles avec les effets specifiques aleatoires des sites d'essence dans le marche de Montreal (Quebec, Canada) durant is periode 1993--1997. Le modele econometrique qui est ainsi specifie et teste, isole un ensemble de quatre variables dont le prix de detail affiche dans un site d'essence ordinaire, la capacite de service du site pendant les heures de pointe, les heures de service et le nombre de sites concurrents au voisinage du site dans un rayon de deux kilometres. Ces quatre facteurs influencent les ventes d'essence dans les stations-service. Les donnees en panel avec les methodes d'estimation robustes (estimateur a distance minimale) sont utilisees pour estimer les parametres du modele de vente. Nous partons avec l'hypothese generale selon laquelle il se developpe une force d'attraction qui attire les clients automobilistes dans chaque site, et qui lui permet de realiser les ventes. Cette capacite d'attraction varie d'un site a un autre et cela est du a la combinaison de l'effort marketing et de l'environnement concurrentiel autour du site. Les notions de voisinage et de concurrence spatiale expliquent les comportements des decideurs qui gerent les sites. Le but de cette these est de developper un outil d'aide a la decision (modele analytique) pour permettre aux gestionnaires des chaines de stations-service d'affecter efficacement les ressources commerciales dans ies points de vente.

  2. Traitement des séquelles de brûlures de la main dans les pays à ressources limitées ; notre expérience en république démocratique du Congo

    PubMed Central

    Kibadi, K.; Moutet, F.

    2015-01-01

    Summary Les séquelles de brûlures de la main sont encore fréquentes dans les pays à ressources limitées. Trente-deux patients, représentant 38 mains, ont été admis et traités, entre le 1er décembre 2010 et le 1er mai 2014 aux Cliniques Universitaires de Kinshasa en République Démocratique du Congo (RDC). nous avons observé 22 patients (69 %) dans le groupe de jeunes (patients âgés de moins de 18 ans), et 10 patients (31 %) chez les adultes (18 à 59 ans). Aucun patient dans le groupe de seniors (60 ans et plus) n’a été observé. Dans le groupe de jeunes, la tranche d’âge de 1 à 5 ans a été la plus atteinte avec 13 malades (40 %). l’accident à la maison était le plus fréquent (72 %). le mécanisme de la brûlure était le plus souvent thermique par flammes (51 %) ou par liquide chaud (34 %). les rétractions et brides sont les lésions le plus observées (84 %). la rétraction dorsale globale « main en griffe» est observée chez 40 % de patients traités, associée à des cicatrices hypertrophiques et chéloïdiennes dans 84 % de cas. Chez les 32 mains traitées chirurgicalement, des excision-greffes ont été réalisées dans 43,7 %, des lambeaux locaux dans 43,7 % et des lambeaux à distance dans 12,5 % de cas. A la sortie de l’hôpital, 84 % de « bons » résultats ont été observés. le suivi a été de 18 mois. le traitement des séquelles de brûlures de la main est possible dans ces pays, exemple de la rDC. Mais les défis à surmonter dans ces pays sont nombreux : la faible accessibilité aux techniques actuelles de la chirurgie plastique, la prise en charge initiale inadéquate des brûlures, la pauvreté. PMID:26668560

  3. The melanocyte lineage in development and disease

    PubMed Central

    Mort, Richard L.; Jackson, Ian J.; Patton, E. Elizabeth

    2015-01-01

    Melanocyte development provides an excellent model for studying more complex developmental processes. Melanocytes have an apparently simple aetiology, differentiating from the neural crest and migrating through the developing embryo to specific locations within the skin and hair follicles, and to other sites in the body. The study of pigmentation mutations in the mouse provided the initial key to identifying the genes and proteins involved in melanocyte development. In addition, work on chicken has provided important embryological and molecular insights, whereas studies in zebrafish have allowed live imaging as well as genetic and transgenic approaches. This cross-species approach is powerful and, as we review here, has resulted in a detailed understanding of melanocyte development and differentiation, melanocyte stem cells and the role of the melanocyte lineage in diseases such as melanoma. PMID:25670789

  4. Sox proteins in melanocyte development and melanoma

    PubMed Central

    Harris, Melissa L.; Baxter, Laura L.; Loftus, Stacie K.; Pavan, William J.

    2010-01-01

    Over ten years has passed since the first Sox gene was implicated in melanocyte development. Since then, we have discovered that SOX5, SOX9, SOX10 and SOX18 all participate as transcription factors that affect key melanocytic genes in both regulatory and modulatory fashions. Both SOX9 and SOX10 play major roles in the establishment and normal function of the melanocyte; SOX10 has been shown to heavily influence melanocyte development and SOX9 has been implicated in melanogenesis in the adult. Despite these advances, the precise cellular and molecular details of how these SOX proteins are regulated and interact during all stages of the melanocyte life cycle remain unknown. Improper regulation of SOX9 or SOX10 is also associated with cancerous transformation, and thus understanding the normal function of SOX proteins in the melanocyte will be key to revealing how these proteins contribute to melanoma. PMID:20444197

  5. Faut-il préférer une technique chirurgicale dans le traitement des ruptures du tendon d'Achille?

    PubMed Central

    Hani, Redouane; Kharmaz, Mohammed; Berrada, Mohammed Saleh

    2015-01-01

    La rupture du tendon d'Achille est de plus en plus fréquente dans le monde et dans notre pays en raison du développement considérable des activités sportives, de l'accroissement de leur intensité et de l'absence de moyens de prévention. Notre travail porte sur une étude concernant 58 cas de rupture du tendon d'Achille, avec un recul moyen compris entre 5 mois et 80 mois. L’âge moyen était de 36 ans, tous les patients inclus ont tous bénéficier d'un traitement chirurgical. Le but de notre étude étant de souligner la supériorité d'une technique chirurgicale par rapport à une autre dans la prise en charge, ainsi qu'une mise au point sur les différents aspects épidémiologiques, cliniques, thérapeutiques et post-thérapeutiques de cette lésion. PMID:26161208

  6. Melanocytic glaucoma in a cairn terrier.

    PubMed

    Hanselman, Beth A

    2002-04-01

    Melanocytic glaucoma, previously known as pigmentary glaucoma, is characterized by diffuse intraocular infiltration of heavily pigmented melanocytes. This unusual ocular disorder has been documented only in the cairn terrier and is considered familial. Treatment strategies are based on evidence that the condition is slowly progressive but not neoplastic. PMID:11963666

  7. Melanocytic glaucoma in a cairn terrier

    PubMed Central

    Hanselman, Beth A.

    2002-01-01

    Melanocytic glaucoma, previously known as pigmentary glaucoma, is characterized by diffuse intraocular infiltration of heavily pigmented melanocytes. This unusual ocular disorder has been documented only in the cairn terrier and is considered familial. Treatment strategies are based on evidence that the condition is slowly progressive but not neoplastic. PMID:11963666

  8. Biological characteristics of mouse skin melanocytes.

    PubMed

    Shi, Zhanquan; Ji, Kaiyuan; Yang, Shanshan; Zhang, Junzhen; Yao, Jianbo; Dong, Changsheng; Fan, Ruiwen

    2016-04-01

    The objective of this research was to evaluate the optimal passage number according to the biological characteristics of mouse skin melanocytes from different passages. Skin punch biopsies harvested from the dorsal region of 2-day old mice were used to establish melanocyte cultures. The cells from passage 4, 7, 10 and 13 were collected and evaluated for their melanogenic activity. Histochemical staining for tyrosinase (TYR) activity and immunostaining for the melanocyte specific markers including S-100 antigen, TYR, tyrosinase related protein 1 (TYRP1), tyrosinase related protein 2 (TYRP2) and micropthalmia associated transcription factor (MITF) confirmed purity and melanogenic capacity of melanocytes from different passages, with better melanogenic activity of passage 10 and 13 cells being observed. Treatment of passage 13 melanocytes with α-melanocyte stimulating hormone (α-MSH) showed increased expression of MITF, TYR and TYRP2 mRNA. However, considering the TYR mRNA dramatically high expression which is the characteristics of melanoma cells, melanocytes from passage 10 was the optimal passage number for the further research. Our results demonstrate culture of pure populations of mouse melanocytes to at least 10 passages and illustrate the potential utility of passage 10 cells for studies of intrinsic and extrinsic regulation of genes controlling pigmentation and coat color in mouse. PMID:26905193

  9. Melanocytic naevi clustered on normal background skin.

    PubMed

    Torchia, D

    2015-04-01

    Several types of maculopapular melanocytic naevi can occur in a multiple form, and be arranged in a nonrandom fashion on the skin. The most frequently reported segmentally grouped naevi are lentigines. Two types of segmentally arranged lentigines probably exist. The first is associated with neurofibromatosis (NF)1 or NF1 signs, features scattered light-brown lesions and can be considered a type of mosaic NF1. By contrast, non-NF1 associated lesions are characterized by densely packed, dark lesions, and can be defined as 'non-NF1 checkerboard-arranged lentigines'. Blue naevi, Spitz naevi and common acquired melanocytic naevi can occur, clustered in an agminated (or cannonball) shape. However, if large enough, they always follow a checkerboard pattern. Hence, such mosaic conditions should be termed 'checkerboard-arranged blue naevi', 'checkerboard-arranged Spitz naevi' and 'checkerboard-arranged common acquired melanocytic naevi'. Segmentally arranged dysplastic melanocytic naevi probably represent a mosaic form of dysplastic naevus syndrome. Dysplastic melanocytic naevi confined to a cutaneous segment could be defined as 'isolated segmental dysplastic naevus syndrome', while segmentally arranged dysplastic melanocytic naevi co-occurring with widespread, nonsegmental dysplastic melanocytic naevi might configure a 'superimposed segmental dysplastic naevus syndrome'. Small congenital melanocytic naevi are always grouped along Blaschko lines. The only other instances following Blaschko lines are the so-called 'linear lentiginous naevus' and a unique case of multiple deep penetrating naevi. PMID:25703021

  10. Desmoplastic Melanocytic Nevus of Oral Mucosa.

    PubMed

    Damm, Douglas D; Fowler, Craig B; Schmidt, David P

    2016-09-01

    The desmoplastic melanocytic nevus is an uncommon variant that easily may be confused with a fibrohistiocytic neoplasm or a desmoplastic melanoma. It is believed that the following report describes the first known example of a desmoplastic melanocytic nevus arising in the oral mucosa. The histopathologic and immunohistochemical features that allow separation from other microscopically similar pathoses are stressed. PMID:26747459

  11. Effets du Parecoxib dans la Prévention des Adhérences abdominales postopératoires: étude expérimentale randomisée chez les rats

    PubMed Central

    Arung, Willy; Tshilombo, François; Odimba, Etienne

    2015-01-01

    Introduction Bien d’études ont été menées sur les adhérences intrapéritonéales, mais aucune unanimité n'est encore acquise sur leur prévention. Le but de notre étude a été d’évaluer le potentiel effet d'un antiinflammatoire, parecoxib dans la prévention des adhérences ainsi que sur la cicatrisation chez des rats. Méthodes Dans un modèle expérimental d'adhérences postopératoires secondaires à des lésions péritonéales par brûlure, 30 rats furent randomisés en trois groupes suivant le mode d'administration de parecoxib (groupe contrôle; intrapéritonéal; intramusculaire. Résultats Le parecoxib a significativement diminué la quantité (p < .05) et la sévérité (p < .01) des adhérences postopératoires dans les deux modèles expérimentaux. Au total, 21 rats ont développé des adhérences, respectivement 9 (100%) dans le groupe A, 5 (50%) dans le groupe B et 7 (70%) dans le groupe C (p = 0.05). Du point de vue de la formation des adhérences au site du traumatisme, dix-neuf rats en ont développé: 9 (100%) dans le groupe A et 5 (50%) pour chacun de deux autres groupes B et C. Une différence significative a été constatée en comparant ces groupes deux à deux: A vs B (p < 0.05); A vs C (p < 0,05). Parecoxib n'a pas compromis la cicatrisation intestinale, ni cutanée. Conclusion Cette étude a montré que le parecoxib pouvait réduire la formation des adhérences postopératoires. La confirmation de la sécurité du parecoxib sur les anastomoses intestinales doit être investiguée au cours d'autres expérimentations. PMID:26966478

  12. Eléments traces dans le sérum des enfants malnutris et bien nourris vivants à Lubumbashi et Kawama dans un contexte d'un environnement de pollution minière

    PubMed Central

    Musimwa, Aimée Mudekereza; Kanteng, Gray Wakamb; Kitoko, Hermann Tamubango; Luboya, Oscar Numbi

    2016-01-01

    Introduction La place des éléments traces métalliques essentiels en nutrition humaine ne peut plus être ignorée. Les déficits d'apports, les carences secondaires souvent sous – estimées, et les carences iatrogènes font le lit de pathologies telles que les infections et autres. D'où leurs dosages ont une importance particulière pour en évaluer la gravité et faciliter une prise en charge précoce ou améliorer le régime alimentaire. Cette étude a eu pour objectif de déterminer le profil sanguin en éléments traces (cuivre, sélénium, zinc, fer, chrome, cobalt, etc) chez les enfants malnutris et biens nourris dans un milieu minier à Lubumbashi. Méthodes Trois cents onze cas ont été colligés, 182 malnutris et 129 biens nourris, dans une étude descriptive transversale, effectuée de juillet 2013 à décembre 2014. Pour lequel un échantillonnage exhaustif a été réalisé. Le dosage des métaux dans le sérum s'est fait à l’ ICP-OES (spectrométrie de masse à plasma gon induit) au laboratoire de l'Office Congolais de Contrôle de Lubumbashi. Résultats Les oligoéléments essentiels (cuivre, zinc, sélénium et fer) se retrouvent à des concentrations très basses chez les enfants malnutris comme chez les biens nourris. L'arsenic, le cadmium, le magnésium et le manganèse se présentent à des concentrations normales par rapport aux valeurs de références chez les enfants biens nourris. L'antimoine, le chrome, le plomb et le cobalt se retrouvent élevés chez les malnutris et biens nourris. Le nickel est normal chez les malnutris et les biens nourris. Le magnésium, manganèse se sont présentés à des taux très bas chez les enfants malnutris. Conclusion Les enfants malnutris et biens nourris présentent une malnutrition aux oligo-éléments essentiels associés aux éléments traces métalliques. Ce qui permet de supposer qu'une carence en micronutriments essentiel favorise l'absorption des métaux lourds. PMID:27583075

  13. Ampleur et impact des évènements indésirables graves liés aux soins: étude d'incidence dans un hôpital du Centre-Est tunisien

    PubMed Central

    Bouafia, Nabiha; Bougmiza, Iheb; Bahri, Fathi; Letaief, Mondher; Astagneau, Pascal; Njah, Mansour

    2013-01-01

    Introduction La prévention des événements indésirables représente une priorité de santé du fait de leur fréquence et de leur gravité potentielle. Ce travail a été mené afin d'avoir un diagnostic de la situation épidémiologique relative aux événements indésirables survenant dans notre hôpital. Méthodes Une étude prospective a été menée auprès de tous les patients qui ont été hospitalisés au CHU Farhat Hached - Sousse (Tunisie) sur une période d'un mois dans quatorze services de l'hôpital. La détection d'évènement indésirable grave (EIG) était basée sur les critères adoptés dans différentes études. Les tests T et Chi 2 ont été utilisés pour identifier les facteurs contribuant à l'apparition d'évènements indésirables. Résultats Au total, 162 EIG ont été identifiés pendant la période. 45% de ces évènements étaient des infections nosocomiales. Ces EIG ont eu comme conséquences un décès chez 9,2% des patients, la mise en jeu du pronostic vital de 26% des patients et la prolongation de la durée de séjour chez 61,7% d'entre eux. L'admission dans des circonstances particulières et l'exposition à des soins invasifs étaient identifiés comme des facteurs de risque potentiels EIG. Conclusion Le renforcement de la stratégie de gestion des risques sanitaires en ciblant préférentiellement le risque infectieux constitue une étape fondamentale dans l'amélioration de la sécurité des patients au sein de notre établissement de santé. PMID:24711868

  14. Maintenance of distinct melanocyte populations in the interfollicular epidermis.

    PubMed

    Glover, James D; Knolle, Stefan; Wells, Kirsty L; Liu, Dianbo; Jackson, Ian J; Mort, Richard L; Headon, Denis J

    2015-07-01

    Hair follicles and sweat glands are recognized as reservoirs of melanocyte stem cells (MSCs). Unlike differentiated melanocytes, undifferentiated MSCs do not produce melanin. They serve as a source of differentiated melanocytes for the hair follicle and contribute to the interfollicular epidermis upon wounding, exposure to ultraviolet irradiation or in remission from vitiligo, where repigmentation often spreads outwards from the hair follicles. It is unknown whether these observations reflect the normal homoeostatic mechanism of melanocyte renewal or whether unperturbed interfollicular epidermis can maintain a melanocyte population that is independent of the skin's appendages. Here, we show that mouse tail skin lacking appendages does maintain a stable melanocyte number, including a low frequency of amelanotic melanocytes, into adult life. Furthermore, we show that actively cycling differentiated melanocytes are present in postnatal skin, indicating that amelanotic melanocytes are not uniquely relied on for melanocyte homoeostasis. PMID:25847135

  15. Haute prévalence du Burnout dans les unités Tunisiennes prenant en charge des patients en fin de vie

    PubMed Central

    Amamou, Badii; Bannour, Ahmed Souhaiel; Ben Hadj Yahia, Meriem; Ben Nasr, Selma; Ben Hadj Ali, Bechir

    2014-01-01

    Introduction Chez le personnel soignant, le burnout touche un infirmier sur trois. Ce taux est plus élevé dans les unités prenant en charge des patients en fin de vie. L'objectif de notre travail était d'évaluer la fréquence du burnout chez les infirmiers qui travaillent en soins de fin de vie. Méthodes Il s'agit d'une étude descriptive transversale réalisée entre le 1er Avril et le 31 Mai 2010. 60 infirmiers de six services de Sousse et de Monastir (Tunisie) ont été recrutés. L'évaluation du burnout a été réalisée par deux échelles: MBI (Maslach Burnout Inventory) et BMS (Burnout Measure Short version). Résultats La prévalence du burnout était de 70%; il était élevé chez 81.7%. 80% avaient un niveau élevé d'épuisement émotionnel, 70% avaient un niveau élevé de dépersonnalisation et 17% avaient un niveau bas de sentiment d'accomplissement personnel. Le burnout était plus élevé chez les hommes (70,8% vs 69,4%; p=0,013); ceux qui voulaient améliorer les conditions du travail (70.2% vs. 66.7%; p= 0.017); du salaire (70.2% vs. 66.7%; p= 0.017) et chez les infirmiers suivi en psychiatrie (71.4% vs. 69.8%; p= 0.008). Conclusion Dans notre étude le niveau de burnout était élevé chez les infirmiers prenant en charge des patients en fin de vie. Il était associé au sexe masculin et à l'insatisfaction des conditions de travail et du salaire. D'autres études longitudinales sont nécessaires pour suivre l'évolution de ce syndrome et mettre des stratégies de prévention adéquates. PMID:25584122

  16. Interprétation cohérente du coefficient de Poisson négatif rapporté dans des multicouches métalliques : rôle du paramètre libre de contrainte

    NASA Astrophysics Data System (ADS)

    Badawi, K. F.; Goudeau, Ph.; Durand, N.

    1998-04-01

    Elastic properties of multilayers with low period thickness show in some cases anomalies which are generally correlated with structural modifications in individual layers. In the recent past, several studies have evidenced using X-ray diffraction in-plane and out-of-plane strains with the same sign. Some authors have then proposed in the case of W/Ni and Nb/Cu metallic superlattices to use a negative Poisson's ratio. This result is surprising because the value of this coefficient in metals is generally positive. In this article, we introduce a novel interpretation mainly based on the experimental determination by sin^2Psi method of the reference parameter (stress-free lattice parameter) used in strain calculations. Then, we show that the introduction of the bulk parameter instead of stress-free parameter for the reference parameter is an unrealistic assumption in the case of thin films and multilayers (W and Ag/Ni) and may thus lead to wrong results which are then in total disagreement with those obtained by other techniques. Therefore, the elastic anomaly concerning Poisson's ratio which has been reported by some authors in scientific literature do not result from real structure of multilayers but from experimental X-ray diffraction data analysis. Les propriétés élastiques dans certains systèmes multicouches de faible période présentent des anomalies qui sont généralement associées à des modifications des propriétés structurales de chacune des couches. Ainsi, plusieurs études ont mis en évidence par diffraction des rayons X des déformations de même signe dans le plan et selon la normale au plan des couches déposées. Certains auteurs ont alors proposé dans le cas de systèmes métalliques W/Ni et Nb/Cu l'utilisation d'un coefficient de Poisson négatif. Ce résultat est surprenant car la valeur de ce coefficient pour les métaux est généralement positive. Dans cet article, nous présentons une nouvelle interprétation reposant sur la d

  17. Hyperspectral imaging of melanocytic lesions.

    PubMed

    Gaudi, Sudeep; Meyer, Rebecca; Ranka, Jayshree; Granahan, James C; Israel, Steven A; Yachik, Theodore R; Jukic, Drazen M

    2014-02-01

    Hyperspectral imaging (HSI) allows the identification of objects through the analysis of their unique spectral signatures. Although first developed many years ago for use in terrestrial remote sensing, this technology has more recently been studied for application in the medical field. With preliminary data favoring a role for HSI in distinguishing normal and lesional skin tissues, we sought to investigate the potential use of HSI as a diagnostic aid in the classification of atypical Spitzoid neoplasms, a group of lesions that often leave dermatopathologists bewildered. One hundred and two hematoxylin and eosin-stained tissue samples were divided into 1 of 4 diagnostic categories (Spitz nevus, Spitz nevus with unusual features, atypical Spitzoid neoplasm, and Spitzoid malignant melanoma) and 1 of 2 control groups (benign melanocytic nevus and malignant melanoma). A region of interest was selected from the dermal component of each sample, thereby maximizing the examination of melanocytes. Tissue samples were examined at ×400 magnification using a spectroscopy system interfaced with a light microscope. The absorbance patterns of wavelengths from 385 to 880 nm were measured and then analyzed within and among groups. All tissue groups demonstrated 3 common absorbance spectra at 496, 533, and 838 nm. Each sample group contained at least one absorption point that was unique to that group. The Spitzoid malignant melanoma category had the highest number of total and unique absorption points for any sample group. The data were then clustered into 12 representative spectral classes. Although each of the sample groups contained all 12 spectral vectors, they did so in differing proportions. These preliminary results reveal differences in the spectral signatures of the Spitzoid lesions examined in this study. Further investigation into a role for HSI in classifying atypical Spitzoid neoplasms is encouraged. PMID:24247577

  18. Melanocytic Nests Arising in Lichenoid Inflammation”: Reappraisal of the Terminology “Melanocytic Pseudonests”

    PubMed Central

    Chung, Hye Jin; Simkin, A. David; Bhawan, Jag

    2015-01-01

    Abstract: Pseudonests or pseudomelanocytic nests represent aggregates of cells and cell fragments, including keratinocytes, macrophages, lymphocytes, and occasional melanocytes. Pseudomelanocytic nests in the setting of lichenoid inflammation can mimic atypical melanocytic proliferations. Several reports documented nonspecific staining of pseudonests with melanoma antigen recognized by T cells-1/Melan-A, which can be detected in the cytoplasm of nonmelanocytic cells. In contrast, nuclear stains, such as MITF and SOX10, avoid this nonmelanocyte cytoplasmic staining. The authors have previously proposed the term melanocytic pseudonests to describe junctional nests with numerous (>2) true melanoma antigen recognized by T cells-1/Melan-A, SOX10, and MITF in a nonmelanocytic lesion with lichenoid inflammation (unilateral lichen planus pigmentosus/erythema dyschromicum perstans). In this study, the authors report another case of this phenomenon arising in a different lichenoid inflammatory dermatitis (lichen planus). The immunophenotype and number of clustered true melanocytes indicate that these dermoepidermal aggregates represent true melanocytic nests and not pseudonests of any type. Therefore, the authors propose the revised terminology of “melanocytic nests arising in lichenoid inflammation” to describe this novel pattern of benign melanocytic reorganization or proliferation in a subset of lichenoid dermatitides. Because this phenomenon can mimic atypical melanocytic proliferations, clinicopathologic correlation is essential for the correct diagnosis. PMID:26588340

  19. Epithelial, non-melanocytic and melanocytic proliferations of the ocular surface.

    PubMed

    Kheir, Wajiha J; Tetzlaff, Michael T; Pfeiffer, Margaret L; Mulay, Kaustubh; Ozgur, Omar; Morrell, Gail; Esmaeli, Bita

    2016-05-01

    Ocular surface tumors are commonly encountered by ophthalmologists and ophthalmic pathologists. These tumors have varied clinical manifestations. In this article, we discuss the most commonly encountered non-melanocytic and melanocytic ocular surface tumors, with emphasis on their common clinical features, morphologic patterns, and prognostic factors. PMID:27021909

  20. "Melanocytic Nests Arising in Lichenoid Inflammation": Reappraisal of the Terminology "Melanocytic Pseudonests".

    PubMed

    Chung, Hye Jin; Simkin, A David; Bhawan, Jag; Wolpowitz, Deon

    2015-12-01

    Pseudonests or pseudomelanocytic nests represent aggregates of cells and cell fragments, including keratinocytes, macrophages, lymphocytes, and occasional melanocytes. Pseudomelanocytic nests in the setting of lichenoid inflammation can mimic atypical melanocytic proliferations. Several reports documented nonspecific staining of pseudonests with melanoma antigen recognized by T cells-1/Melan-A, which can be detected in the cytoplasm of nonmelanocytic cells. In contrast, nuclear stains, such as MITF and SOX10, avoid this nonmelanocyte cytoplasmic staining. The authors have previously proposed the term melanocytic pseudonests to describe junctional nests with numerous (>2) true melanoma antigen recognized by T cells-1/Melan-A, SOX10, and MITF in a nonmelanocytic lesion with lichenoid inflammation (unilateral lichen planus pigmentosus/erythema dyschromicum perstans). In this study, the authors report another case of this phenomenon arising in a different lichenoid inflammatory dermatitis (lichen planus). The immunophenotype and number of clustered true melanocytes indicate that these dermoepidermal aggregates represent true melanocytic nests and not pseudonests of any type. Therefore, the authors propose the revised terminology of "melanocytic nests arising in lichenoid inflammation" to describe this novel pattern of benign melanocytic reorganization or proliferation in a subset of lichenoid dermatitides. Because this phenomenon can mimic atypical melanocytic proliferations, clinicopathologic correlation is essential for the correct diagnosis. PMID:26588340

  1. Quels agents incriminés dans les mycoses du pied ? Enquête auprès des diabétiques consultant au CHU Mohammed VI de Marrakech

    PubMed Central

    Chegour, Hakima; El Ansari, Nawal; El Mghari, Ghizlane; Tali, Abdelali; Zoughaghi, Laila; Sebbani, Majda; Amine, Mohamed

    2014-01-01

    Les infections mycosiques du pied constituent un motif fréquent de consultation chez les diabétiques, le diabète constituant à la fois un facteur favorisant et aggravant les lésions cutanéomuqueuses. L'objectif de ce travail était d'identifier la flore mycologique locale responsable des lésions du pied chez le diabétique et déterminer les facteurs favorisant la survenue de mycoses. Il s'agissait d'une étude transversale intéressant des diabétiques suivis en consultation; un prélèvement mycologique, avec examen direct et culture, a été réalisé devant toute suspicion clinique de lésion mycosique. Quatre-vingt-deux patients ont été inclus. L'hémoglobine glycosylée moyenne a été de9,2% ± 2,23. Un intertrigo inter orteil a été noté dans 90,2% des cas; l'examen mycologique était positif dans 64,8% des cas, avec 18 cas de Trichophyton rubrum et 11 cas de Candida albicans. Une atteinte unguéale a été suspectée chez 65,9% patients; la culture a mis en évidence un Trichosporon pathogène chez sept patients, un Candida albicansdans six cas, un Trichophyton rubrum dans quatre cas, avec trois cas de Trichophyton mentagrophytes et deux cas de Scytalidium dimidiatum. L’étude analytique, après confirmation mycologique, en fonction des principales caractéristiques des patients a montré que l'atteinte mycosique du pied est significativement corrélée au déséquilibre glycémique. Ce travail a montré la prédominance du Trichophyton rubrum dans les lésions d'intertrigo inter orteil et du Trichosporon dans les onychomycoses, avec une prédominance globale plus globale plus élevée du TR. PMID:25170372

  2. Déterminants de l'utilisation des méthodes contraceptives dans la zone de santé Mumbunda à Lubumbashi, République Démocratique du Congo

    PubMed Central

    Matungulu, Charles Matungulu; Kandolo, Simon Ilunga; Mukengeshayi, Abel Ntambue; Nkola, Angèle Musau; Mpoyi, Dorcas Ilunga; Mumba, Sylvie Katanga; Kabamba, Julie Ndayi; Cowgill, Karen; Kaj, Françoise Malonga

    2015-01-01

    Introduction Augmenter la prévalence contraceptive s'incarne dans les objectifs des tous les acteurs des programmes qui visent de réduire la mortalité maternelle et infantile, d'améliorer la santé reproductive des adolescents, de lutter contre le VIH/SIDA et les infections sexuellement transmissible (IST), de promouvoir le bien-être familial et de ralentir la croissance démographique. L'objectif de cette étude était de déterminer la prévalence contraceptive moderne et identifier les facteurs qui sont liés à l'utilisation des méthodes contraceptives dans la zone de santé de Mumbunda. Méthodes Une étude transversale à visé analytique a été effectuée auprès des femmes âgées de 15 à 49 ans en union maritale, de Mai à Juin 2014. Grâce à un questionnaire pré testé et validé, nous avons récolté les données par interview sur les caractéristiques sociodémographiques, obstétricales ainsi que sur la pratique contraceptive. Le logiciel SPSS version 21 nous a permis d'analyser les données. Résultats Au total 500 femmes ont été incluses dans cette étude dont l’âge moyen était de 27,9±6,1 ans. La prévalence contraceptive moderne était de 27,6%. L'attitude (ORa= 4,79; IC95%: 1,59-14,43; p<0,001), le niveau de connaissance des méthodes contraceptives (ORa=1,87; IC95%: 1,22-2,87; p<0,001), le soutien du conjoint (ORa=1,87; IC95%: 1,22-2,87; p<0,001) étaient significativement associés à l'utilisation des méthodes contraceptives modernes. Conclusion Tout effort d'augmentation de la prévalence contraceptive devrait cibler l'attitude, le niveau de connaissance de méthodes et le soutien du conjoint afin d'optimiser l'utilisation de la contraception moderne dans la zone de santé (ZS) Mumbunda. PMID:26977237

  3. Cytolytic antibodies to melanocytes in vitiligo.

    PubMed

    Cui, J; Arita, Y; Bystryn, J C

    1993-06-01

    Patients with vitiligo have been found to have circulating antibodies to pigment cells. To evaluate the functional activity of these antibodies, a highly sensitive europium release assay was used to compare complement-mediated cytolysis of human melanocytes by sera of 56 patients with vitiligo (20 with active disease, 25 with inactive disease, 11 with unidentified disease activity) and 47 control individuals. Significant melanocyte lysis was mediated by 32 (57%) of the patients with vitiligo but by only three (6%) of the control sera (p < 0.001), and by 17 (85%) of 20 patients with active vitiligo versus 11 (44%) of 25 patients with inactive disease (p < 0.025). Mean melanocyte lysis by vitiligo sera was 24% versus 6% by control sera (p < 0.0001). A subset of 12 vitiligo sera with high titers of cytolytic antibodies to melanocytes (34% mean cytolysis) reacted minimally (< 2% mean cytolysis) to a panel of control cells that included human and murine melanomas, human fibroblasts, lung carcinoma, and rhabdomyosarcoma. These findings indicate that antibodies present in patients with vitiligo have the functional ability to selectively kill melanocytes and are more common in active disease. These observations support, but do not prove, the hypothesis that vitiligo is an autoimmune disease and that anti-pigment cell antibodies have a role in inducing the disease. PMID:8496621

  4. Incertitude dans les mesures de courant : un obstacle dans la caractérisation des composants en électronique de puissance

    NASA Astrophysics Data System (ADS)

    Farjah, E.; Barbaroux, J.; Perret, R.

    1993-07-01

    The aim of this paper is to clarify the need for the most accurate current measurement applied to the characterization of the power electronic components. The focus is on the behaviour of the normally used high quality high bandwidth current transformers and other sensors to a fast varying high di/dt test current furnished by a new developed test current generator. In this paper after explaining the new strategy of the test generator, different current transformers are tested and characterized and a detailed comparative experimental study is carried out using a non-inductive shunt as the reference. Finally some general remarks and the necessary precautions and different measurement problems are listed and discussed. Le but de cet article est d'essayer de lever les obstacles rencontrés lors des mesures de courant servant à la caractérisation des composants en électronique de puissance. Nous nous sommes penchés sur les différences entre les réponses de quelques capteurs de haute qualité. Après une brève explication du principe d'un générateur de courant de test spécialement conçu pour cette étude, nous comparons les réponses de plusieurs transformateurs de courant par rapport à un shunt aselfique pris pour référence. Enfin nous abordons les différents aspects concernant les précautions qu'il est nécessaire de prendre pour réaliser ce type de mesure.

  5. Germline mutations in BAP1 predispose to melanocytic tumors

    PubMed Central

    Wiesner, Thomas; Obenauf, Anna C.; Murali, Rajmohan; Fried, Isabella; Griewank, Klaus G.; Ulz, Peter; Windpassinger, Christian; Wackernagel, Werner; Loy, Shea; Wolf, Ingrid; Viale, Agnes; Lash, Alex E.; Pirun, Mono; Socci, Nicholas D.; Rütten, Arno; Palmedo, Gabriele; Abramson, David; Offit, Kenneth; Ott, Arthur; Becker, Jürgen C.; Cerroni, Lorenzo; Kutzner, Heinz; Bastian, Boris C.; Speicher, Michael R.

    2012-01-01

    Common acquired melanocytic nevi are benign neoplasms that are composed of small uniform melanocytes and typically present as flat or slightly elevated, pigmented lesions on the skin. We describe two families with a new autosomal dominant syndrome characterized by multiple skin-colored, elevated melanocytic tumors. In contrast to common acquired nevi, the melanocytic neoplasms in affected family members ranged histopathologically from epithelioid nevi to atypical melanocytic proliferations that showed overlapping features with melanoma. Some affected patients developed uveal or cutaneous melanomas. Segregating with this phenotype, we found inactivating germline mutations of the BAP1 gene. The majority of melanocytic neoplasms lost the remaining wild-type allele of BAP1 by various somatic alterations. In addition, we found BAP1 mutations in a subset of sporadic melanocytic neoplasms showing histologic similarities to the familial tumors. These findings suggest that loss of BAP1 is associated with a clinically and morphologically distinct type of melanocytic neoplasm. PMID:21874003

  6. Links between Schwann cells and melanocytes in development and disease.

    PubMed

    Van Raamsdonk, Catherine D; Deo, Mugdha

    2013-09-01

    Melanocytes are pigment-producing cells that reside in the skin, eyes, ears, heart, and central nervous system meninges of mammals. Schwann cells are glial cells, which closely associate with peripheral nerves, myelinating, and sheathing them. Melanocytes and Schwann cells both arise from the neural crest during development, and some melanocytes arise directly from Schwann cell precursors lining developing spinal nerves. In this review, we explore the connections between melanocytes and Schwann cells in development and transformation. PMID:23815504

  7. Systèmes d'imagerie à haute résolution dans le domaine des Rayons X pour le Laser Mégajoule

    NASA Astrophysics Data System (ADS)

    Champeaux, J.-Ph.; Troussel, Ph.; Boutin, J.-Y.; Lidove, G.; Marmoret, R.; Soullié, G.; Rosch, R.

    2006-12-01

    Le principe de la fusion par confinement inertiel consiste à faire imploser une cible sphérique de petite taille, millimétrique, remplie d'un mélange de deutérium et de tritium sous l'action des 240 faisceaux lasers impulsionnels de très grande puissance du LMJ. Les études de cette physique d'implosion (mise en vitesse, symétrie d'implosion, instabilités hydrodynamiques) et de l'allumage (traceurs, point chaud) font appel aux techniques de l'imagerie et de la radiographie à haute résolution spatiale (μm) et temporelle (ps) avec sélection spectrale dans le domaine d'énergie de photons comprise entre 100 eV et 20 keV. Plusieurs Systèmes d'Imagerie X (SIX), à haute résolution spatiale, ont donc été développés par le CEA-DIF et mis en œuvre sur la Ligne d'Intégration Laser (LIL) implantée au CEA-CESTA. Dans cet article nous présentons les principaux SIX, à base de microscopes à miroirs. Un exemple de microscope prototype nommé PIXEL (Plasma Imageur X pour les Expériences Lasers) développé pour le LMJ est présenté. Nous portons l'accent sur les problèmes technologiques liés à l'environnement LMJ.

  8. Profil étiologique des surdités neurosensorielle sévère et profonde de l'enfant dans la région du centre-nord du Maroc

    PubMed Central

    Ridal, Mohammed; Outtasi, Naouar; Taybi, Zainab; Boulouiz, Redouan; Chaouki, Sanae; Boubou, Meryem; Maaroufi, Mustapha; Benmansour, Najib; Zaki, Zouheir; Ouldim, Karim; Barakat, Hamid; Hida, Mustapha; Tizniti, Siham; El Alami, Mohamed Noreddine

    2014-01-01

    Introduction Le diagnostic d'une surdité profonde est possible dès les premiers jours de vie. Or, le développement du langage et l'intégration scolaire et professionnelle ne sont pas possible que si la surdité est prise en charge précocement. L’établissement d'un diagnostc étiologique a des implications pronostiques et thérapeutiques. Méthodes C'est une étude rétrospective allant de Juin 2009 au mois de Janvier 2012 ayant recensé 250 cas d'enfants porteurs d'une surdité sévère et profonde. Résultats La moyenne d’âge au moment de l'annonce du diagnostic est de 3.7 ans. Les étiologies prédominantes sont les surdités génétiques dans 35.6% suivies des surdités acquises dans 30.8% des cas. Dans 34.4% des cas aucune étiologie n'a pu être retrouvée. Conclusion Cette étude met en évidence la prédominance éventuelle de causes génétiques de la surdité neurosensorielle de l'enfant au Maroc, et souligne la nécessité d'améliorer les politiques de prévention des maladies infectieuses et de dépistage de la surdité néonatale. Cependant, des analyses moléculaires plus ciblées et la réalisation d'un scanner des rochers systématiques sont nécessaires pour évaluer plus précisément la contribution des étiologies génétiques. PMID:25018837

  9. La Greffe de Peau dans le Traitement des Sequelles de la Main Brulee. A Propos de 152 Cas - Experience du Service de Chirurgie Plastique du Centre Hospitalier Universitaire Ibn-Sina, Rabat, Maroc

    PubMed Central

    El Mazouz, S.; Fejjal, N.; Hafidi, J.; Cherkab, L.; Mejjati, H.; Belfqih, R.; Gharib, N.; Abbassi, A.

    2010-01-01

    Summary La main est fréquemment exposée aux brûlures, entraînant des séquelles esthétiques et fonctionnelles. Le traitement de ces séquelles est surtout chirurgical et consiste en la greffe de peau, dont le type dépend de la localisation de la brûlure et du type des séquelles. Dans ce travail rétrospectif, nous rapportons une série de 152 cas de brûlures des mains colligés au service de chirurgie plastique du Centre Hospitalier Universitaire Ibn-Sina de Rabat sur une période de dix ans, allant de 1998 à 2007. Les indications thérapeutiques dépendent du type de séquelles et de la localisation de la brûlure. En tout, 97 patients ont bénéficié d'une greffe cutanée, dont 76% par greffe de peau totale, 21% par greffe de peau demi-épaisse et 3% par peau fine. Les séquelles des brûlures des mains posent un problème thérapeutique majeur, malgré la diversité des procédés chirurgicaux, d'où l'intérêt de la prévention. PMID:21991196

  10. Giant Congenital Melanocytic Nevi and Neurocutaneous Melanosis

    PubMed Central

    Araújo, Catarina; Pardal, Francisco; Brito, Celeste

    2015-01-01

    Introduction. The major medical concern with giant congenital melanocytic nevi CMN is high risk of developing cutaneous melanoma, leptomeningeal melanoma, and neurocutaneous melanocytosis. Case Report. A 30-year-old woman with a giant congenital melanocytic nevus covering nearly the entire right thoracodorsal region and multiple disseminated melanocytic nevi presented with neurological symptoms. Cerebral magnetic resonance imaging revealed a large expansive lesion in the left frontal region. Postsurgically pathological diagnosis revealed characteristics of melanoma. Immunohistochemical examination showed S100(+), HMB45(+), MelanA(+), and MiTF(+). She received radiotherapy with temozolomide followed by two more chemotherapy cycles with temozolomide. She followed a rapidly progressive course, reflecting widespread leptomeningeal infiltration, and she died of multiorgan failure seven months after diagnosis of cerebral melanoma. Discussion. This patient was diagnosed as having a neurocutaneous melanosis with malignant widespread leptomeningeal infiltration. Diffuse spinal involvement is unusual and is described in only another patient. PMID:25722729

  11. The ultrastructure of conjunctival melanocytic tumors.

    PubMed Central

    Jakobiec, F A

    1984-01-01

    The ultrastructure of conjunctival melanocytic lesions in 49 patients was evaluated to find significant differences between benign and malignant cells. The patients studied included 9 with benign epithelial (racial) melanosis, 2 with pigmented squamous cell papillomas, 16 with conjunctival nevi, 18 with primary acquired melanosis, and 11 with invasive nodules of malignant melanoma. In benign epithelial melanosis, dendritic melanocytes were situated along the basement membrane region of the conjunctival epithelium, with one basilar dendritic melanocyte lodged among every five or six basilar keratinocytes. The dendritic melanocytes extended arborizing cellular processes between the basilar and among the suprabasilar keratinocytes, which manifested considerable uptake of melanin granules into their cytoplasm. The benign dendritic melanocytes possessed nuclei with clumped heterochromatin at the nuclear membrane, small, tightly wound nucleoli, and large, elongated, fully melaninized melanin granules. In two patients with benign hyperplasia of the dendritic melanocytes, occasional dendritic melanocytes were located in a suprabasilar position, but were always separated from each other by keratinocytes or their processes. In the two black patients with benign pigmented squamous papillomas, the benign dendritic melanocytes were located hapharzardly at all levels of the acanthotic epithelium and not just along the basement membrane region. Melanin uptake by the proliferating keratinocytes was minimal. In benign melanocytic nevi of the conjunctiva, nevus cells within the intraepithelial junctional nests displayed a more rounded cellular configuration; short villi and broader cellular processes suggestive of abortive dendrites were found. The nuclear chromatin pattern was clumped at the nuclear membrane, but the nucleoli were somewhat larger than those of benign dendritic melanocytes in epithelial melanosis. The melanosomes were smaller and rounder than those in dendritic

  12. Étude de la répartition des courants de Foucault pulsés dans une configuration de contrôle non destructif

    NASA Astrophysics Data System (ADS)

    Bour, J.-C.; Zubiri, E.; Vasseur, P.; Billat, A.

    1996-01-01

    Adjusting an experimental device of control by eddy-currents in sinusoidal or pulse mode requires the optimization of a certain number of parameters. Generally, the implementation of the latter operations is long and delicate, since it is issued of many compromises. The simulation study presented in this paper can be considered as a qualitative help because it specifies the the behaviour of the different parameters implied in the adjustment of the experimental defect reserach. First, we prove the influence of the lift-off on the defect detention's sensitivity of the flat sensor we used. Next we give prominence to the fact, in practice, we cannot disregard the geometry of the sensor, as we could do in theory. This result will lead us to define a family of curves showing the evolution of the depth of penetration as a function of the pulse's duration for different coil radii. We also determine the maximal sensor's sensitivity area, with the aim of locating the defect detected in the plate with precision. Finally, we prove the dependency between the true value of the depth of penetration and the thickness of the considered metallic plate. This very important result should equally be taken under consideration in the case of a real control. La mise au point d'un dispositif expérimental de contrôle par courants de Foucault, en mode sinusoïdal ou impulsionnel, nécessite l'optimisation d'un certain nombre de paramètres. Cette optimisation est généralement longue et délicate à exécuter en pratique puisqu'elle résulte de plusieurs compromis. L'étude en simulation présentée ici peut être considéré comme une aide plutôt qualitative, puisqu'elle précise le comportement des différents paramètres impliqués dans la mise en point de la recherche expérimentale de défauts. Nous montrons dans un premier temps l'influence de la distance capteur-cible sur la sensibilité du capteur à détecter un défaut. Nous mettons ensuite en évidence le fait de la g

  13. Generation of Human Melanocytes from Induced Pluripotent Stem Cells

    PubMed Central

    Okada, Yohei; Akamatsu, Wado; Kuwahara, Reiko; Ohyama, Manabu; Amagai, Masayuki; Matsuzaki, Yumi; Yamanaka, Shinya; Okano, Hideyuki; Kawakami, Yutaka

    2011-01-01

    Epidermal melanocytes play an important role in protecting the skin from UV rays, and their functional impairment results in pigment disorders. Additionally, melanomas are considered to arise from mutations that accumulate in melanocyte stem cells. The mechanisms underlying melanocyte differentiation and the defining characteristics of melanocyte stem cells in humans are, however, largely unknown. In the present study, we set out to generate melanocytes from human iPS cells in vitro, leading to a preliminary investigation of the mechanisms of human melanocyte differentiation. We generated iPS cell lines from human dermal fibroblasts using the Yamanaka factors (SOX2, OCT3/4, and KLF4, with or without c-MYC). These iPS cell lines were subsequently used to form embryoid bodies (EBs) and then differentiated into melanocytes via culture supplementation with Wnt3a, SCF, and ET-3. Seven weeks after inducing differentiation, pigmented cells expressing melanocyte markers such as MITF, tyrosinase, SILV, and TYRP1, were detected. Melanosomes were identified in these pigmented cells by electron microscopy, and global gene expression profiling of the pigmented cells showed a high similarity to that of human primary foreskin-derived melanocytes, suggesting the successful generation of melanocytes from iPS cells. This in vitro differentiation system should prove useful for understanding human melanocyte biology and revealing the mechanism of various pigment cell disorders, including melanoma. PMID:21249204

  14. Melanocytic Nevus of the Tarsal Conjunctiva

    PubMed Central

    Yazıcı, Bülent; Bilge, Ayşe Dolar; Yağcı, Ayşe; Naqadan, Faisal; Altıntepe, Filiz

    2016-01-01

    Background: Melanocytic nevus is a rare occurrence in the tarsal conjunctiva and only 7 well-described cases have been reported previously in the English literature. Case Report: The medical records of 4 patients with tarsal conjunctival melanocytic nevus were reviewed, together with the relevant literature. All patients (3 women and 1 man; age range: 17 – 40 years) had been referred with a suspicion of melanoma. There was one tarsal nevus in the lower eyelid in 3 patients and 2 nevi in the upper eyelid in 1 patient. All lesions were darkly pigmented with irregular borders and were associated with a history of a recent growth in size. An intralesional cyst was present in 1 nevus only. After surgical excision, no recurrence or complication occurred during the follow-up period (range: 7 – 48 months). Conclusion: Tarsal melanocytic nevus has been described in detail in 11 cases, including these 4 cases, in the English literature. The lesion arose from the lower eyelid in all cases except one. Tarsal melanocytic nevi may frequently display clinical features suggesting melanoma, such as advanced patient age, recent growth, dark and irregular pigmentation, nodularity, hypervascularity, and the absence of an intralesional cyst. After total excision, nevus recurrence or malignant transformation has not been reported.

  15. Role of TRPM in melanocytes and melanoma

    PubMed Central

    Guo, Huazhang; Carlson, J. Andrew; Slominski, Andrzej

    2012-01-01

    Transient receptor potential (TRP) cation channel superfamily plays important roles in variety cellular processes including polymodal cellular sensing, cell adhesion, cell polarity, proliferation, differentiation, and apoptosis. One of its subfamilies are TRPM channels. mRNA expression of its founding member, TRPM1 (melastatin), correlates with terminal melanocytic differentiation and loss of its expression has been identified as an important diagnostic and prognostic marker for primary cutaneous melanoma. Because TRPM1 gene codes two transcripts: TRPM1 channel protein in its exons, and miR-211 in one of its introns, we propose a dual role for TRPM1 gene where the loss of TRPM1 channel protein is an excellent marker of melanoma aggressiveness, while the expression of miR-211 is linked to the tumor suppressor function of TRPM1. In addition, three other members of this subfamily, TRPM 2, 7 and 8 are implicated in regulation of melanocytic behavior. TRPM2 is capable of inducing melanoma apoptosis and necrosis. TRPM7 can be a protector and detoxifier in both melanocytes and melanoma cells. TRPM8 can mediate agonist-induced melanoma cell death. Therefore, we propose that TRPM1, TRPM2, TRPM7, and TRPM8 play crucial roles in melanocyte physiology and melanoma oncology, and are excellent diagnostic markers and theraputic targets. PMID:22897572

  16. Acquired unilateral melanocytic nevi in otherwise normal skin.

    PubMed

    Yu, Xijun; Nagai, Hiroshi; Nishigori, Chikako; Horikawa, Tatsuya

    2008-01-01

    We describe a case with numerous melanocytic nevi in otherwise normal skin. A 5-year-old girl presented with more than 100 small pigment lesions on her left arm, shoulder and upper back without underlying light brown macule. The pigment lesions were first found on her left forearm at 3 months old and gradually increased along with her growth. Skin biopsy from a pigmented lesion shows a pathological change in compound-type melanocytic nevus without any atypical changes. Speckled lentiginous nevus is known to have multiple melanocytic lesions on the underlying brown macule from birth. Partial unilateral lentiginosis is characterized by unilateral lentigines with histopathological changes in lentigo but not melanocytic proliferation in the dermis. Agminated melanocytic nevi tend to be clustered together in a circumscribed area, whereas in the present case melanocytic nevi were segmentally arranged but not agminated. We consider that this is an unusual type of mosaicism of melanocytic disorders. PMID:18401177

  17. Réalisation d'un appareillage a lame vibrante pour l'étude des lignes de flux dans les supraconducteurs à haute température critique

    NASA Astrophysics Data System (ADS)

    Woirgard, J.; Salmon, E.; Gaboriaud, R. J.; Rabier, J.

    1994-03-01

    A very sensitive apparatus using the vibrating reed technique in a magnetic field is described. This new technic is an internal friction measurement which has been developed and applied to the study of vortex pinning in high T_c type II superconductors. The vibrating reed is simply used as a sample holder for the superconductor which can be oriented thin films, bulk samples or powders. The salient feature of this experimental set-up is the excitation mode of the reed for which the imposed vibration frequency can be freely chosen in the range 10^{-4}-10 Hz. Furthermore, the measurement sensitivity improves the performances obtained up to now by such similar apparatus as forced torsion pendulums. Damping values corresponding to phase lags between 10^{-5} and 10^{-4} radian can be readily obtained for vibration frequencies in the range 10^{-1} 10 Hz. Some preliminary results show damping peaks which might be due to the so-called fusion of the vortex network obtained with thin films whose thickness is 1000 Å and with textured bulk samples of YBaCuO. Une nouvelle technique basée sur la mesure du frottement intérieur en vibrations forcées est appliquée à l'étude de l'ancrage des vortex dans les oxydes supraconducteurs à haute température critique. Dans cette méthode la lame, excitée électrostatiquement, voit son rôle limité à celui de porte-échantillon sur lequel peuvent être disposés des couches minces, des échantillons massifs ou des poudres. L'originalité de cet appareillage réside dans la conception du mode d'excitation de la lame : la fréquence d'oscillation forcée peut être choisie dans une large gamme allant de 10^{-4} Hz à quelques dizaines de hertz. D'autre part, la sensibilité de la mesure améliore sensiblement les performances obtenues jusqu'à ce jour en vibrations forcées. Des amortissements correspondant à des déphasages compris entre à 10^{-5} et 10^{-4} radian peuvent être facilement mesurés. Les premiers essais r

  18. Melanocyte antigen triggers autoimmunity in human psoriasis.

    PubMed

    Arakawa, Akiko; Siewert, Katherina; Stöhr, Julia; Besgen, Petra; Kim, Song-Min; Rühl, Geraldine; Nickel, Jens; Vollmer, Sigrid; Thomas, Peter; Krebs, Stefan; Pinkert, Stefan; Spannagl, Michael; Held, Kathrin; Kammerbauer, Claudia; Besch, Robert; Dornmair, Klaus; Prinz, Jörg C

    2015-12-14

    Psoriasis vulgaris is a common T cell-mediated inflammatory skin disease with a suspected autoimmune pathogenesis. The human leukocyte antigen (HLA) class I allele, HLA-C*06:02, is the main psoriasis risk gene. Epidermal CD8(+) T cells are essential for psoriasis development. Functional implications of HLA-C*06:02 and mechanisms of lesional T cell activation in psoriasis, however, remained elusive. Here we identify melanocytes as skin-specific target cells of an HLA-C*06:02-restricted psoriatic T cell response. We found that a Vα3S1/Vβ13S1 T cell receptor (TCR), which we had reconstituted from an epidermal CD8(+) T cell clone of an HLA-C*06:02-positive psoriasis patient specifically recognizes HLA-C*06:02-positive melanocytes. Through peptide library screening, we identified ADAMTS-like protein 5 (ADAMTSL5) as an HLA-C*06:02-presented melanocytic autoantigen of the Vα3S1/Vβ13S1 TCR. Consistent with the Vα3S1/Vβ13S1-TCR reactivity, we observed numerous CD8(+) T cells in psoriasis lesions attacking melanocytes, the only epidermal cells expressing ADAMTSL5. Furthermore, ADAMTSL5 stimulation induced the psoriasis signature cytokine, IL-17A, in CD8(+) T cells from psoriasis patients only, supporting a role as psoriatic autoantigen. This unbiased analysis of a TCR obtained directly from tissue-infiltrating CD8(+) T cells reveals that in psoriasis HLA-C*06:02 directs an autoimmune response against melanocytes through autoantigen presentation. We propose that HLA-C*06:02 may predispose to psoriasis via this newly identified autoimmune pathway. PMID:26621454

  19. Melanocyte antigen triggers autoimmunity in human psoriasis

    PubMed Central

    Arakawa, Akiko; Siewert, Katherina; Stöhr, Julia; Besgen, Petra; Kim, Song-Min; Rühl, Geraldine; Nickel, Jens; Vollmer, Sigrid; Thomas, Peter; Krebs, Stefan; Pinkert, Stefan; Spannagl, Michael; Held, Kathrin; Kammerbauer, Claudia; Besch, Robert; Dornmair, Klaus

    2015-01-01

    Psoriasis vulgaris is a common T cell–mediated inflammatory skin disease with a suspected autoimmune pathogenesis. The human leukocyte antigen (HLA) class I allele, HLA-C*06:02, is the main psoriasis risk gene. Epidermal CD8+ T cells are essential for psoriasis development. Functional implications of HLA-C*06:02 and mechanisms of lesional T cell activation in psoriasis, however, remained elusive. Here we identify melanocytes as skin-specific target cells of an HLA-C*06:02–restricted psoriatic T cell response. We found that a Vα3S1/Vβ13S1 T cell receptor (TCR), which we had reconstituted from an epidermal CD8+ T cell clone of an HLA-C*06:02–positive psoriasis patient specifically recognizes HLA-C*06:02–positive melanocytes. Through peptide library screening, we identified ADAMTS-like protein 5 (ADAMTSL5) as an HLA-C*06:02–presented melanocytic autoantigen of the Vα3S1/Vβ13S1 TCR. Consistent with the Vα3S1/Vβ13S1-TCR reactivity, we observed numerous CD8+ T cells in psoriasis lesions attacking melanocytes, the only epidermal cells expressing ADAMTSL5. Furthermore, ADAMTSL5 stimulation induced the psoriasis signature cytokine, IL-17A, in CD8+ T cells from psoriasis patients only, supporting a role as psoriatic autoantigen. This unbiased analysis of a TCR obtained directly from tissue-infiltrating CD8+ T cells reveals that in psoriasis HLA-C*06:02 directs an autoimmune response against melanocytes through autoantigen presentation. We propose that HLA-C*06:02 may predispose to psoriasis via this newly identified autoimmune pathway. PMID:26621454

  20. Etude des effets du martelage repetitif sur les contraintes residuelles

    NASA Astrophysics Data System (ADS)

    Hacini, Lyes

    L'assemblage par soudage peut engendrer des contraintes residuelles. Ces contraintes provoquent des fissurations prematurees et un raccourcissement de la duree de vie des composants. Dans ce contexte, le martelage robotise est utilise pour relaxer ces contraintes residuelles. Trois volets sont presentes: le premier est l'evaluation des effets des impacts unitaires repetes sur le champ de contraintes developpe dans des plaques d'acier inoxydable austenitique 304L vierges ou contenant des contraintes residuelles initiales. Dans la deuxieme partie de ce projet, le martelage est applique grace au robot SCOMPI. Les contraintes residuelles induites et relaxees par martelage sont ensuite mesurees par la methode des contours, qui a ete adaptee a cet effet. Dans la troisieme partie, le martelage est modelise par la methode des elements finis. Un modele axisymetrique developpe grace au logiciel ANSYS permet de simuler des impacts repetes d'un marteau elastique sur une plaque ayant un comportement elastoplastique.

  1. Les facteurs prédictifs de malignité dans la prise en charge des tumeurs parotidiennes: à propos de 76 cas

    PubMed Central

    Bouaity, Brahim; Darouassi, Youssef; Chihani, Mehdi; Touati, Mohamed Mliha; Ammar, Haddou

    2016-01-01

    La pathologie tumorale de la glande parotide est complexe et pose un problème diagnostique et thérapeutique. Une bonne analyse des facteurs prédictifs de malignité de ces tumeurs parotidiennes semble actuellement nécessaire en vue d'une meilleure planification thérapeutique. Le but de ce travail est d’étudier les facteurs prédictifs de malignité dans les tumeurs parotidiennes à travers une étude rétrospective sur 76 cas de tumeurs de la parotide traités au service d'Oto-Rhino-Laryngologie et de Chirurgie Cervico-Faciale de l'hôpital militaire Avicenne de Marrakech entre janvier 2000 et décembre 2012. Il s'agit de 40 femmes et 36 hommes. L’âge moyen était de 44 ans pour les tumeurs bénignes alors qu'il était de 50 ans pour les tumeurs malignes. Le délai moyen de consultation était de 24 mois pour les tumeurs bénignes et de 16 mois pour les tumeurs malignes. La tuméfaction de la région parotidienne a été un signe révélateur constant chez tous les malades. La malignité est évoquée cliniquement devant la douleur, la paralysie faciale, la fixité par rapport au plan superficiel ou profond et la présence d'adénopathie. L'IRM constitue désormais l'examen de choix dans l'exploration des masses tumorales parotidiennes avec une bonne valeur diagnostique de malignité ou de bénignité. La cytoponction à l'aiguille fine n'a pas de valeur que si elle est positive. La parotidectomie exploratrice avec examen anatomopathologique extemporané demeure la clé du diagnostic positif. Les tumeurs parotidiennes bénignes représentent l'entité la plus fréquente (80%) et l'adénome pléomorphe demeure le type histologique prédominant (61%). Quant aux tumeurs malignes, elles sont plutôt rares, dominées essentiellement par les carcinomes muco épidermoides (6,5%). Le traitement chirurgical est l'option de choix souvent associée à un curage ganglionnaire et une radiothérapie pour les tumeurs malignes. La paralysie faciale est la complication

  2. Analyse de la prise en charge du nouveau-né dans le cadre de la stratégie nationale de subvention des accouchements et des soins obstétricaux et néonatals d'urgence au Centre Hospitalier Universitaire Pédiatrique Charles de Gaulle, Ouagadougou (Burkina Faso)

    PubMed Central

    Ouédraogo, Solange Odile Yugbaré; Yougbaré, Nestor; Kouéta, Fla; Dao; Ouédraogo, Moussa; Lougué, Claudine; Ludovic, Kam; Traoré, Ramata Ouédraogo; Yé, Diarra

    2015-01-01

    Introduction Il s'agit d'analyser la prise en charge du nouveau-né dans le cadre de la stratégie na-tionale de subvention des accouchements et des soins obstétricaux et néonatals d'urgence mis en place par le gouvernement du Burkina Faso en 2006. Méthodes Nous avons menée une étude à visée descriptive et analytique comportant un volet ré-trospectif du 01 janvier 2006 au 31 décembre 2010 portant sur les paramètres épidémiologiques, cliniques des nouveau-nés hospitalisés et un volet prospectif du 3 octobre 2011 au 29 février 2012 par une entrevue des accompagnateurs des nouveau-nés et des prestataires des services de santé. Résultats Les hospitalisations ont augmenté de 43,65% entre 2006 à 2010 Le taux de mortalité néo-natale hospitalière qui était de 11,04% a connu une réduction moyenne annuelle de 3,95%. L'entrevue a porté sur 110 accompagnateurs et 76 prestataires. La majorité des prestataires (97,44%) et des ac-compagnateurs (88,18%) étaient informés de la stratégie mais n'avait pas une connaissance exacte de sa définition. Les prestataires (94,74%) ont signalé des ruptures de médicaments, consommables médicaux et des pannes d’ appareils de laboratoire et d'imagerie. Parmi les accompagnateurs (89%) disaient être satisfaits des services offerts et (72,89%) trouvaient les coûts abordables mais évoquaient les difficultés du transport. Conclusion: La subvention a amélioré la prise en charge du nou-veau-né mais son optimisation nécessiterait une meilleur information et implication de tous les acteurs. Conclusion La subvention a amélioré la prise en charge du nouveau-né mais son optimisation nécessiterait une meilleur information et implication de tous les acteurs. PMID:26161166

  3. Pirin Inhibits Cellular Senescence in Melanocytic Cells

    PubMed Central

    Licciulli, Silvia; Luise, Chiara; Scafetta, Gaia; Capra, Maria; Giardina, Giuseppina; Nuciforo, Paolo; Bosari, Silvano; Viale, Giuseppe; Mazzarol, Giovanni; Tonelli, Chiara; Lanfrancone, Luisa; Alcalay, Myriam

    2011-01-01

    Cellular senescence has been widely recognized as a tumor suppressing mechanism that acts as a barrier to cancer development after oncogenic stimuli. A prominent in vivo model of the senescence barrier is represented by nevi, which are composed of melanocytes that, after an initial phase of proliferation induced by activated oncogenes (most commonly BRAF), are blocked in a state of cellular senescence. Transformation to melanoma occurs when genes involved in controlling senescence are mutated or silenced and cells reacquire the capacity to proliferate. Pirin (PIR) is a highly conserved nuclear protein that likely functions as a transcriptional regulator whose expression levels are altered in different types of tumors. We analyzed the expression pattern of PIR in adult human tissues and found that it is expressed in melanocytes and has a complex pattern of regulation in nevi and melanoma: it is rarely detected in mature nevi, but is expressed at high levels in a subset of melanomas. Loss of function and overexpression experiments in normal and transformed melanocytic cells revealed that PIR is involved in the negative control of cellular senescence and that its expression is necessary to overcome the senescence barrier. Our results suggest that PIR may have a relevant role in melanoma progression. PMID:21514450

  4. Autophagy as a melanocytic self-defense mechanism.

    PubMed

    Setaluri, Vijayasaradhi

    2015-05-01

    Defects in autophagy have implications for melanocyte survival and manifestations of skin pigmentary disorders. Zhang et al. (2015) show that mouse melanocytes lacking the autophagy protein Atg7 undergo premature senescence in vitro and accumulate products of oxidative damage, despite activation of the redox response. Interestingly, contrary to previous findings, the melanocyte-specific deficiency in autophagy did not cause major defects in melanosome biogenesis, nor did it produce visually striking changes in mouse coat color. PMID:25882462

  5. Ancient melanocytic nevus: a simulator of malignant melanoma.

    PubMed

    Kerl, Helmut; Wolf, Ingrid H; Kerl, Katrin; Cerroni, Lorenzo; Kutzner, Heinz; Argenyi, Zsolt B

    2011-04-01

    Ancient melanocytic nevus (AN) is an unusual but distinctive melanocytic neoplasm within the spectrum of simulators of malignant melanoma. This report describes 13 patients with AN where a long follow-up information was available. Histopathology is characterized by 2 populations of melanocytes, namely, one with large pleomorphic cells and the other with small melanocytes. A few mitotic figures may be present exceptionally. MIB-1 (Ki67) proliferation marker reveals an overall low nuclear labeling index. Additional important findings are stromal degenerative changes. AN must be especially differentiated from dermal melanoma arising in a nevus. PMID:21399448

  6. Growth of melanocytes in human epidermal cell cultures

    SciTech Connect

    Staiano-Coico, L.; Hefton, J.M.; Amadeo, C.; Pagan-Charry, I.; Madden, M.R.; Cardon-Cardo, C. )

    1990-08-01

    Epidermal cell cultures were grown in keratinocyte-conditioned medium for use as burn wound grafts; the melanocyte composition of the grafts was studied under a variety of conditions. Melanocytes were identified by immunohistochemistry based on a monoclonal antibody (MEL-5) that has previously been shown to react specifically with melanocytes. During the first 7 days of growth in primary culture, the total number of melanocytes in the epidermal cultures decreased to 10% of the number present in normal skin. Beginning on day 2 of culture, bipolar melanocytes were present at a mean cell density of 116 +/- 2/mm2; the keratinocyte to melanocyte ratio was preserved during further primary culture and through three subpassages. Moreover, exposure of cultures to mild UVB irradiation stimulated the melanocytes to proliferate, suggesting that the melanocytes growing in culture maintained their responsiveness to external stimuli. When the sheets of cultured cells were enzymatically detached from the plastic culture flasks before grafting, melanocytes remained in the basal layer of cells as part of the graft applied to the patient.

  7. Melanocytes as instigators and victims of oxidative stress.

    PubMed

    Denat, Laurence; Kadekaro, Ana L; Marrot, Laurent; Leachman, Sancy A; Abdel-Malek, Zalfa A

    2014-06-01

    Epidermal melanocytes are particularly vulnerable to oxidative stress owing to the pro-oxidant state generated during melanin synthesis, and to the intrinsic antioxidant defenses that are compromised in pathologic conditions. Melanoma is thought to be oxidative stress driven, and melanocyte death in vitiligo is thought to be instigated by a highly pro-oxidant state in the epidermis. We review the current knowledge about melanin and the redox state of melanocytes, how paracrine factors help counteract oxidative stress, the role of oxidative stress in melanoma initiation and progression and in melanocyte death in vitiligo, and how this knowledge can be harnessed for melanoma and vitiligo treatment. PMID:24573173

  8. Neurotized Congenital Melanocytic Nevus Resembling a Pigmented Neurofibroma

    PubMed Central

    Singh, Nidhi; Chandrashekar, Laxmisha; Kar, Rakhee; Sylvia, Mary Theresa; Thappa, Devinder Mohan

    2015-01-01

    Neurotized congenital melanocytic nevus and pigmented neurofibroma (PNF) are close mimics and pose a clinicopathological challenge. We present a case of pigmented hypertrichotic plaque over lumbosacral region and discuss the differential diagnosis and its clinical, histopathological and immunohistochemistry features which may aid in differentiation. We highlight the difficulties faced in differentiating neurotized congenital melanocytic nevus from pigmented neurofibroma. PMID:25657396

  9. Exosomes released by keratinocytes modulate melanocyte pigmentation

    PubMed Central

    Cicero, Alessandra Lo; Delevoye, Cédric; Gilles-Marsens, Floriane; Loew, Damarys; Dingli, Florent; Guéré, Christelle; André, Nathalie; Vié, Katell; van Niel, Guillaume; Raposo, Graça

    2015-01-01

    Cells secrete extracellular vesicles (EVs), exosomes and microvesicles, which transfer proteins, lipids and RNAs to regulate recipient cell functions. Skin pigmentation relies on a tight dialogue between keratinocytes and melanocytes in the epidermis. Here we report that exosomes secreted by keratinocytes enhance melanin synthesis by increasing both the expression and activity of melanosomal proteins. Furthermore, we show that the function of keratinocyte-derived exosomes is phototype-dependent and is modulated by ultraviolet B. In sum, this study uncovers an important physiological function for exosomes in human pigmentation and opens new avenues in our understanding of how pigmentation is regulated by intercellular communication in both healthy and diseased states. PMID:26103923

  10. Exosomes released by keratinocytes modulate melanocyte pigmentation.

    PubMed

    Lo Cicero, Alessandra; Delevoye, Cédric; Gilles-Marsens, Floriane; Loew, Damarys; Dingli, Florent; Guéré, Christelle; André, Nathalie; Vié, Katell; van Niel, Guillaume; Raposo, Graça

    2015-01-01

    Cells secrete extracellular vesicles (EVs), exosomes and microvesicles, which transfer proteins, lipids and RNAs to regulate recipient cell functions. Skin pigmentation relies on a tight dialogue between keratinocytes and melanocytes in the epidermis. Here we report that exosomes secreted by keratinocytes enhance melanin synthesis by increasing both the expression and activity of melanosomal proteins. Furthermore, we show that the function of keratinocyte-derived exosomes is phototype-dependent and is modulated by ultraviolet B. In sum, this study uncovers an important physiological function for exosomes in human pigmentation and opens new avenues in our understanding of how pigmentation is regulated by intercellular communication in both healthy and diseased states. PMID:26103923

  11. Meningeal Melanocytes in the Mouse: Distribution and Dependence on Mitf

    PubMed Central

    Gudjohnsen, Stefán A. H.; Atacho, Diahann A. M.; Gesbert, Franck; Raposo, Graca; Hurbain, Ilse; Larue, Lionel; Steingrimsson, Eirikur; Petersen, Petur Henry

    2015-01-01

    Summary: Melanocytes are pigment producing cells derived from the neural crest. They are primarily found in the skin and hair follicles, but can also be found in other tissues including the eye, ear and heart. Here, we describe the distribution of pigmented cells in C57BL/6J mouse meninges, the membranes that envelope the brain. These cells contain melanosomes of all four stages of development and they depend on Microphthalmia associated transcription factor (MITF), the master regulator of melanocyte development, suggesting that they are bona-fide melanocytes. The location of these pigmented cells is consistent with the location of meningeal melanomas in humans and animal models. Significance: Here, we document and define pigmented cells in the meninges of the mouse brain and confirm that they are melanocytes. This is important for understanding the role of this cell type and for understanding primary meningeal melanoma, a rare disease that likely arises from normal meningeal melanocytes. PMID:26635543

  12. What are melanocytes really doing all day long...?

    PubMed

    Plonka, P M; Passeron, T; Brenner, M; Tobin, D J; Shibahara, S; Thomas, A; Slominski, A; Kadekaro, A L; Hershkovitz, D; Peters, E; Nordlund, J J; Abdel-Malek, Z; Takeda, K; Paus, R; Ortonne, J P; Hearing, V J; Schallreuter, K U

    2009-09-01

    Everyone knows and seems to agree that melanocytes are there to generate melanin - an intriguing, but underestimated multipurpose molecule that is capable of doing far more than providing pigment and UV protection to skin (1). What about the cell that generates melanin, then? Is this dendritic, neural crest-derived cell still serving useful (or even important) functions when no-one looks at the pigmentation of our skin and its appendages and when there is essentially no UV exposure? In other words, what do epidermal and hair follicle melanocytes do in their spare time - at night, under your bedcover? How much of the full portfolio of physiological melanocyte functions in mammalian skin has really been elucidated already? Does the presence or absence of melanocytes matter for normal epidermal and/or hair follicle functions (beyond pigmentation and UV protection), and for skin immune responses? Do melanocytes even deserve as much credit for UV protection as conventional wisdom attributes to them? In which interactions do these promiscuous cells engage with their immediate epithelial environment and who is controlling whom? What lessons might be distilled from looking at lower vertebrate melanophores and at extracutaneous melanocytes in the endeavour to reveal the 'secret identity' of melanocytes? The current Controversies feature explores these far too infrequently posed, biologically and clinically important questions. Complementing a companion viewpoint essay on malignant melanocytes (2), this critical re-examination of melanocyte biology provides a cornucopia of old, but under-appreciated concepts and novel ideas on the slowly emerging complexity of physiological melanocyte functions, and delineates important, thought-provoking questions that remain to be definitively answered by future research. PMID:19659579

  13. Prévalence de l'hypertension artérielle dans la population des meuniers de la ville de Lubumbashi, République Démocratique du Congo

    PubMed Central

    Ngombe, Léon Kabamba; Cowgill, Karen; Monga, Ben Bondo; Ilunga, Benjamin Kabyla; Stanis, Wembonyama Okitotsho; Numbi, Oscar Luboya

    2015-01-01

    Introduction L'objectif était de comparer la prévalence de l'hypertension artérielle chez les meuniers dans la ville de Lubumbashi qui sont exposés d'une manière permanente aux bruits des machines de transformation des céréales à la prévalence de l'hypertension artérielle chez un groupe des gardiens. Méthodes Quic'est une étude descriptive transversale qui a concerné 286 meuniers et 115 agents d'une entreprise de gardiennage. Apres un consentement éclairé, un auto questionnaire a été administré aux enquêtés et des mesures de poids, taille, et tension artérielle ont été prises. Résultats La prévalence de l'HTA chez les meuniers était 49.3% et celle des gardes était 20.9%, pour un ratio de prévalence de 2.4. significativement élevée par rapport aux contrôles (49.3% vs 20.9%) et le ratio de prévalence était de 2.4. Les facteurs de risque tels que: l’âge, l'indice de masse corporelle, l'ancienneté, la durée de travail ont été significativement élevés chez les meuniers par rapport aux gardiens. Conclusion Nous avons trouvé une prévalence élevée de l'HTA chez les meuniers. Nos résultats suggèrent que cette prévalence est probablement due à l'environnement du milieu de travail des meuniers (bruits, vibration des machines) et ce dernier constitue un facteur de risque de l'hypertension artérielle. PMID:26889333

  14. Early diagnosis and successful treatment of paraneoplastic melanocytic proliferation

    PubMed Central

    Jansen, Joyce C G; Van Calster, Joachim; Pulido, Jose S; Miles, Sarah L; Vile, Richard G; Van Bergen, Tine; Cassiman, Catherine; Spielberg, Leigh H; Leys, Anita M

    2015-01-01

    Background Paraneoplastic melanocytic proliferation (bilateral diffuse uveal melanocytic proliferation, BDUMP) is a rare but devastating disease that causes progressive visual loss in patients who usually have an occult malignancy. Visual loss occurs as a result of paraneoplastic changes in the uveal tissue. Methods In a masked fashion, the serum of two patients with BDUMP was evaluated for the presence of cultured melanocyte elongation and proliferation (CMEP) factor using cultured human melanocytes. We evaluated the efficacy of plasmapheresis as a treatment modality early in the disease in conjunction with radiation and chemotherapy. Results The serum of the first case patient was investigated after plasmapheresis and did not demonstrate proliferation of cultured human melanocytes. The serum of the second case was evaluated prior to treatment with plasmapheresis and did induce this proliferation. These findings are in accordance with the diminution of CMEP factor after plasmapheresis. Treatment with plasmapheresis managed to stabilise the ocular disease progression in both patients. Conclusions In the past, visual loss due to paraneoplastic melanocytic proliferation was considered progressive and irreversible. We treated two patients successfully with plasmapheresis and demonstrated a relation between CMEP factor in the serum of these patients and proliferation of cultured melanocytes. PMID:25908835

  15. Protein Expression Analysis of Melanocyte Differentiation Antigen TRP-2.

    PubMed

    Avogadri, Francesca; Gnjatic, Sacha; Tassello, Jodie; Frosina, Denise; Hanson, Nicole; Laudenbach, Megan; Ritter, Erika; Merghoub, Taha; Busam, Klaus J; Jungbluth, Achim A

    2016-03-01

    Melanocyte differentiation antigens, such as gp100, tyrosinase, and Melan-A and their corresponding antibodies HMB45, T311, and A103, are major diagnostic tools in surgical pathology. Little is known about tyrosinase-related protein 2 (TRP-2, or dopachrome tautomerase/DCT) another melanocyte differentiation antigen, which is an enzymatic component of melanogenesis. We identified a commercial reagent to TRP-2, monoclonal antibody (mAb) C-9 and undertook a comprehensive analysis to assess its specificity and usefulness for surgical pathology. Subsequently, we analyzed panels of normal tissues and tumors. We show that TRP-2 is regularly expressed in melanocytes of the normal skin. In cutaneous nevi, TRP-2 is present in junctional as well as in dermal nevocytes. In malignant tumors, C-9 reactivity is restricted to melanocytic and related lesions and present in 84% and 58% of primary and metastatic melanomas, respectively. Ten primary melanomas of the anorectal mucosa were all positive. Like the other melanocyte differentiation antigens, TRP-2 was absent in 6 desmoplastic melanomas. Also, only 2 of 9 angiomyolipomas were TRP-2 positive. We conclude that mAb C-9 is a valuable reagent for the analysis of TRP-2 expression in archival surgical pathology material. The expression pattern of TRP-2 in melanocytic and related lesions appears to parallel other melanocyte differentiation antigens, although the overall incidence is lower than other antigens, such as Melan-A or gp100. PMID:26894771

  16. Melanocyte regeneration in vitiligo requires WNT beneath their wings

    PubMed Central

    Harris, John E.

    2015-01-01

    Melanocytes in patients with vitiligo possess intrinsic abnormalities that contribute to its pathogenesis. In this issue, Regazzetti, et al. report that CXCL10 expression reflects subtle inflammation in normal-appearing skin but not in stable depigmented lesions, supporting the hypothesis that melanocytes themselves initiate autoimmune inflammation prior to clinically evident disease. In addition, they find that oxidative stress in melanocytes impairs WNT signaling and that targeting this pathway induces melanoblast differentiation. Thus, activating the WNT pathway may serve as an adjunctive strategy to support repigmentation in patients with vitiligo. PMID:26569586

  17. Giant congenital melanocytic nevus in a bulgarian newborn.

    PubMed

    Chokoeva, A A; Fioranelli, M; Roccia, M G; Lotti, T; Wollina, U; Tchernev, G

    2016-01-01

    Giant congenital melanocytic nevus (GCMN) is a rare disorder affecting 1 in 200,000–500,000 live births. Central nervous system defects such as spina bifida, meningocele, Dandy Walker malformation may accompany it and thus cause significant morbidity. Despite the related risk for malignant transformation, GCMNs may be associated with neurocutaneous melanosis, a rare syndrome in which a giant CMN or multiple smaller CMNs are accompanied by melanocytic deposition in the brain and the spinal cord. We present a case of a 5-day-old newborn with giant congenital melanocytic nevus on his back, as we discuss the diagnostic and treatment approach. PMID:27373137

  18. La campagne s'urbanise: résultats d'un dépistage du diabète et des dysglycémies dans une zone rurale de la région de Marrakech

    PubMed Central

    Ennazk, Laila; El M'ghari, Ghizlane; El Ansari, Nawal

    2014-01-01

    Introduction Le diabète constitue un problème de santé publique au Maroc. L'augmentation de sa prévalence se fait en parallèle avec l'augmentation des chiffres de l'obésité et de l'hypertension artérielle (HTA). Les facteurs environnementaux dont l'urbanisation influencent avec force cet état des lieux. En milieu rural, la tendance tend à s'inverser du fait du changement des habitudes de vie. Notre travail avait comme but de dépister la dysglycémie dans une commune rurale de la région de Marrakech. Méthodes Ce travail de dépistage fait sur une journée a concerné une population tout-venant de 200 personnes. La glycémie capillaire à jeun, la tension artérielle, le poids, la taille, l'indice de masse corporelle et le tour de taille ont été mesurés pour toutes les personnes qui se sont présentées. Résultats Deux cent sujets ont été examinés. 31% des sujets examinés étaient diabétiques. Chez les non diabétiques, 57,9% avaient une glycémie capillaire à jeun au-delà de 1,1g/l, 51,2% entre 1,1 g/l et 1,26 g/l et 48,7% au-delà de 1,26 g/l. Sur le plan tensionnel, 95% des patients examinés n'étaient pas connus hypertendus. L'obésité androïde touche 63,7% des patients examinés. Conclusion Les chiffres retrouvés lors de cette caravane médicale sont supérieurs à nos attentes. L'urbanisation du milieu rural a un impact sur le profil métabolique et tensionnel de cette population; ce qui devrait impliquer une démarche préventive de santé publique. PMID:25667693

  19. Radiations cosmiques : danger dans l'Espace

    NASA Astrophysics Data System (ADS)

    Bonnet-Bidaud, J. M.; Dzitko, H.

    2000-06-01

    Au sol, l'atmosphere nous protege plus ou moins bien. Mais dans l'espace ou a bord des avions de ligne, l'homme est directement expose aux rayonnements cosmiques qui peuvent etre mortels. Un veritable frein a la presence humaine prolongee dans l'espace. Une menace que les agences spatiales prennent tres au serieux.

  20. From Melanocyte to Metastatic Malignant Melanoma

    PubMed Central

    Bandarchi, Bizhan; Ma, Linglei; Navab, Roya; Seth, Arun; Rasty, Golnar

    2010-01-01

    Malignant melanoma is one of the most aggressive malignancies in human and is responsible for almost 60% of lethal skin tumors. Its incidence has been increasing in white population in the past two decades. There is a complex interaction of environmental (exogenous) and endogenous, including genetic, risk factors in developing malignant melanoma. 8–12% of familial melanomas occur in a familial setting related to mutation of the CDKN2A gene that encodes p16. The aim of this is to briefly review the microanatomy and physiology of the melanocytes, epidemiology, risk factors, clinical presentation, historical classification and histopathology and, more in details, the most recent discoveries in biology and genetics of malignant melanoma. At the end, the final version of 2009 AJCC malignant melanoma staging and classification is presented. PMID:20936153

  1. Vasculogenic mimicry: lessons from melanocytic tumors.

    PubMed

    Spiliopoulos, Konstantinos; Peschos, Dimitrios; Batistatou, Anna; Ntountas, Ioannis; Agnantis, Niki; Kitsos, Georgios

    2015-01-01

    Tumor cell vasculogenic mimicry refers to the formation of tumor cell-lined vessels that contribute to tumor neovascularization and nutrient and oxygen supply. These tumor cells express many endothelial and stem cell markers, resulting in them having a unique phenotype. This phenomenon is observed in a variety of neoplasms, such as glioblastomas and sarcomas, as well as breast, ovarian, liver and lung carcinomas. It is also evident in melanocytic lesions, regardless of their benign or malignant nature. The biochemical and molecular events that regulate vasculogenic mimicry provide opportunities for development of novel forms of tumor-targeted treatments. Furthermore, the presence of this process in a tumor might have prognostic implications. PMID:25977376

  2. A comparative review of melanocytic neoplasms.

    PubMed

    Smith, S H; Goldschmidt, M H; McManus, P M

    2002-11-01

    Melanoma is a devastating disease frequently encountered within both veterinary and human medicine. Molecular changes linked with neoplastic transformation of melanocytes include mutations in genes that encode proteins intrinsic to the regulatory pathways of two tumor suppressor proteins (retinoblastoma protein and p53), proto-oncogene mutation to oncogenes, altered expression of epithelial cadherin and CD44 adhesion molecules, and upregulation of angiogenic factors and other growth factors. Histologic evaluation of the primary mass is the most common means of diagnosis, with cytology used more frequently to document metastasis. Melanoma's highly variable histologic and cytologic patterns can make diagnosis by either method problematic. Adherent epithelioid morphology, including signet ring forms, and nonadherent round and spindle forms are recognized, with pigmentation an inconsistent finding. The site of the tumor, the thickness of the primary tumor or depth of invasion, and the number of mitotic figures per high-power field or per millimeter are used histologically to predict biologic behavior, whereas site and degree of pleomorphism are typically used for cytologic preparations. Diagnosis of amelanotic melanoma can be aided by ancillary diagnostic techniques. Tumor cells are usually positive for vimentin, S100, neuron-specific enolase, and Melan-A, and negative for cytokeratin. Melan-A as a positive marker is not as sensitive as the others are but is likely more specific. Monoclonal antibodies to human melanosome-specific antigens 1 and 5 cross-react with canine antigens for a combined sensitivity rate of 83%. Mouse monoclonal antibody IBF9 specifically recognizes canine melanoma antigen and also has good sensitivity. Serologic markers, including cytokines, cell adhesion molecules, and melanoma-inhibitory activity, are being investigated as potential sentinels of melanoma. Currently, there is no single diagnostic technique capable of differentiating benign from

  3. Congenital melanocytic nevus: two clinicopathological forms.

    PubMed

    Magaña, Mario; Sánchez-Romero, Elizabeth; Magaña, Pablo; Beck-Magaña, Andrés; Magaña-Lozano, Mario

    2015-01-01

    Congenital melanocytic nevus (CMN) is a hamartomatous disease for which many attempts at classification have been proposed. This disease is relevant not only because of its functional and esthetic implications but also because it is a well-documented precursor to malignant melanoma. We performed a clinical and pathological prospective study of 200 cases of CMN and were able to identify 2 different forms of CMN, each one with biological, clinical, and histopathological features and criteria that are consistent and repeatable. We propose to name them types I and II. Type I CMN is the most common, usually, if not always, a single lesion, it consists of a plaque that involves only 1 anatomic region and does not go beyond it; type I CNM grows in proportion to the growth of the child, melanoma rarely develops from it, and when it does it usually arises at the dermoepidermal junction. Its histopathology shows cords, strands, nests, and single units of melanocytes spreading between collagen bundles only in the dermis and frequently the epidermis too, but without trespassing to the hypodermis, that is, it is superficial. Type II CMN is always made up of many lesions, one of them being very large and surrounded by many lesions; histopathologically, it involves not only the skin but also deeper structures, sometimes bone and central nervous system; therefore, it is deep; when melanoma develops, it does in the dermal component and usually from the largest plaque. This type of CMN is the one that develops neurocutaneous melanocytosis. This system is not only easy and logical but it also has biologic advantages and the clinical-pathological correlation and criteria are repeatable by clinicians and pathologists. PMID:25140664

  4. Monitoring human melanocytic cell responses to piperine using multispectral imaging

    NASA Astrophysics Data System (ADS)

    Samatham, Ravikant; Phillips, Kevin G.; Sonka, Julia; Yelma, Aznegashe; Reddy, Neha; Vanka, Meenakshi; Thuillier, Philippe; Soumyanath, Amala; Jacques, Steven

    2011-03-01

    Vitiligo is a depigmentary disease characterized by melanocyte loss attributed most commonly to autoimmune mechanisms. Currently vitiligo has a high incidence (1% worldwide) but a poor set of treatment options. Piperine, a compound found in black pepper, is a potential treatment for the depigmentary skin disease vitiligo, due to its ability to stimulate mouse epidermal melanocyte proliferation in vitro and in vivo. The present study investigates the use of multispectral imaging and an image processing technique based on local contrast to quantify the stimulatory effects of piperine on human melanocyte proliferation in reconstructed epidermis. We demonstrate the ability of the imaging method to quantify increased pigmentation in response to piperine treatment. The quantization of melanocyte stimulation by the proposed imaging technique illustrates the potential use of this technology to quickly assess therapeutic responses of vitiligo tissue culture models to treatment non-invasively.

  5. Timeline and distribution of melanocyte precursors in the mouse heart.

    PubMed

    Brito, Flavia Carneiro; Kos, Lidia

    2008-08-01

    Apart from the well-studied melanocytes of the skin, eye and inner ear, another population has recently been described in the heart. In this study, we tracked cardiac melanoblasts using in situ hybridization with a dopachrome tautomerase (Dct) probe and Dct-LacZ transgenic mice. Large numbers of melanoblasts were found in the atrioventricular (AV) endocardial cushions at embryonic day (E) 14.5 and persisted in the AV valves into adulthood. The earliest time Dct-LacZ-positive cells were observed in the AV endocardial cushions was E12.5. Prior to that, between E10.5 and E11.5, small numbers of melanoblasts traveled between the post-otic area and third somite along the anterior and common cardinal veins and branchial arch arteries with other neural crest cells expressing CRABPI. Cardiac melanocytes were not found in the spotting mutants Ednrb s-l/s-l and Kit w-v/w-v, while large numbers were observed in transgenic mice that overexpress endothelin 3. These results indicate that cardiac melanocytes depend on the same signaling molecules known to be required for proper skin melanocyte development and may originate from the same precursor population. Cardiac melanocytes were not found in zebrafish or frog but were present in quail suggesting an association between cardiac melanocytes and four-chambered hearts. PMID:18444965

  6. Melanocyte Stem Cells as Potential Therapeutics in Skin Disorders

    PubMed Central

    Lee, Ju Hee; Fisher, David E.

    2015-01-01

    Introduction Melanocytes produce pigment granules that color both skin and hair. In the hair follicles melanocytes are derived from stem cells (MelSC) that are present in hair bulges or sub-bulge regions and function as melanocyte reservoirs. Quiescence, maintenance, activation, and proliferation of MelSC are controlled by specific activities in the microenvironment that can influence the differentiation and regeneration of melanocytes. Therefore, understanding MelSC and their niche may lead to use of MelSC in new treatments for various pigmentation disorders. Areas covered We describe here pathophysiological mechanisms by which melanocyte defects lead to skin pigmentation disorders such as vitiligo and hair graying. The development, migration, and proliferation of melanocytes and factors involved in the survival, maintenance, and regeneration of MelSC are reviewed with regard to the biological roles and potential therapeutic applications in skin pigmentation diseases. Expert Opinion MelSC biology and niche factors have been studied mainly in murine experimental models. Human MelSC markers or methods to isolate them are much less well understood. Identification, isolation and culturing of human MelSC would represent a major step toward new biological therapeutic options for patients with recalcitrant pigmentary disorders or hair graying. By modulating the niche factors for MelSC it may one day be possible to control skin pigmentary disorders and prevent or reverse hair graying. PMID:25104310

  7. Distinctive molecular responses to ultraviolet radiation between keratinocytes and melanocytes.

    PubMed

    Sun, Xiaoyun; Kim, Arianna; Nakatani, Masashi; Shen, Yao; Liu, Liang

    2016-09-01

    Solar ultraviolet radiation (UVR) is the major risk factor for skin carcinogenesis. To gain new insights into the molecular pathways mediating UVR effects in the skin, we performed comprehensive transcriptomic analyses to identify shared and distinctive molecular responses to UVR between human keratinocytes and melanocytes. Keratinocytes and melanocytes were irradiated with varying doses of UVB (10, 20 and 30 mJ/cm(2) ) then analysed by RNA-Seq at different time points post-UVB radiation (4, 24 and 72 h). Under basal conditions, keratinocytes and melanocytes expressed similar number of genes, although they each expressed a distinctive subset of genes pertaining to their specific cellular identity. Upon UVB radiation, keratinocytes displayed a clear pattern of time- and dose-dependent changes in gene expression that was different from melanocytes. The early UVB-responsive gene set (4 h post-UVR) differed significantly from delayed UVB-responsive gene sets (24 and 72 h). We also identified multiple novel UVB signature genes including PRSS23, SERPINH1, LCE3D and CNFN, which were conserved between melanocyte and keratinocyte lines from different individuals. Taken together, our findings elucidated both common and distinctive molecular features between melanocytes and keratinocytes and uncovered novel UVB signature genes that might be utilized to predict UVB photobiological effects on the skin. PMID:27119462

  8. Functionally distinct melanocyte populations revealed by reconstitution of hair follicles in mice.

    PubMed

    Aoki, Hitomi; Hara, Akira; Motohashi, Tsutomu; Osawa, Masatake; Kunisada, Takahiro

    2011-02-01

    Hair follicle reconstitution analysis was used to test the contribution of melanocytes or their precursors to regenerated hair follicles. In this study, we first confirmed the process of chimeric hair follicle regeneration by both hair keratinocytes and follicular melanocytes. Then, as first suggested from the differential growth requirements of epidermal skin melanocytes and non-cutaneous or dermal melanocytes, we confirmed the inability of the latter to be involved as follicular melanocytes to regenerate hair follicles during the hair reconstitution assay. This clear functional discrimination between non-cutaneous or dermal melanocytes and epidermal melanocytes suggests the presence of two different melanocyte cell lineages, a finding that might be important in the pathogenesis of melanocyte-related diseases and melanomas. PMID:21054816

  9. Accentuation récente de la vulnérabilité liée à la mobilité du trait de côte et à la salinisation des sols dans l'archipel de Kerkennah (Tunisie)

    NASA Astrophysics Data System (ADS)

    Etienne, Lucile

    2014-10-01

    L'archipel de Kerkennah, situé dans le Golfe de Gabès en Tunisie, est composé d'une dizaine de petites îles dont le relief est très plat et la lithologie meuble et fragile. Les espaces les plus bas sont occupés par des sebkhas, espaces salés et stériles. L'évolution du climat et l'élévation relative du niveau de la mer ainsi que les Évolutions importantes des modes de vie et de production locaux ont conduit à des changements majeurs dans l'occupation du sol. Dans ce contexte, cette thèse vise à comprendre l'évolution de la vulnérabilité liée à la mobilité du trait de côte et à la salinisation des sols depuis les années 1960. Des études diachroniques de photo-interprétation et télédétection ont été réalisées afin d'observer et mesurer l'évolution de l'occupation du sol, du trait de côte et de l'extension des surfaces de sebkhas. Grâce à ces études et à des relevés de terrain, il est apparu que les côtes subissent majoritairement une érosion significative (0,12m/an) et que les surfaces de sebkhas s'étendent. Ces phénomènes physiques, associés aux évolutions de l'occupation des sols et aux modes de gestion parfois peu adaptés, ont conduit à une augmentation de la vulnérabilité liée à la mobilit:é du trait de côte et à la salinisation des sols. Les résultats d'un questionnaire, proposé à 139 personnes, laissent penser que la population locale perçoit le retrait de la côte et la salinisation des sols comme étant des phénomènes préoccupants et dangereux. Ainsi le contexte local est plutôt cohérent avec des phénomènes dommageables réels et une population qui semble les connaître. Cependant, la gestion littorale dans l'archipel ne semble prendre en compte ni la vulnérabilité existante, ni la perception et les connaissances de la population locale. Même si la gestion intégrée des zones côtières est préconisée en Tunisie, elle n'est pas mise en place dans l'archipel de Kerkennah.

  10. Proton pump inhibitors decrease melanogenesis in melanocytes

    PubMed Central

    BAEK, SEUNG-HWA; LEE, SANG-HAN

    2015-01-01

    Proton pump inhibitors (PPIs) are widely used as inhibitors of gastric juice secretion for treatment of gastroesophageal reflux disease. However, there are no previous studies of the effects on melanogenesis resulting from PPI treatments. Therefore, the aim of the present study was to investigate the effects of PPIs on melanogenesis in melan-a cells derived from immortalized mouse melanocytes. Tyrosinase activity and copper-chelating activity were measured spectrophotometrically. In addition, the melanin content and viability of melan-a cells treated with PPIs were assessed and the mRNA levels of melanogenesis-associated genes were measured by reverse transcription-polymerase chain reaction. Treatment with rabeprazole, but not the other PPIs tested, resulted in strong, dose-dependent inhibition of mushroom tyrosinase (TYR). By contrast, each of the PPIs tested exhibited copper-chelating activity. Treatment of melan-a cells with 100 µM concentrations of the PPIs resulted in significantly reduced melanin synthesis and reduced expression of several melanogenesis-associated genes, including TYR, TYR-related protein-1 (TRP-1) and TRP-2, and microphthalmia-associated transcription factor, but did not result in cytotoxic effects. These results suggest that PPIs inhibit melanin biosynthesis in melan-a cells via the downregulation of melanogenesis-associated genes. Furthermore, the findings indicate that PPIs in general could be utilized as skin-whitening agents and/or as biomaterial for treating hyperpigmentation disorders. PMID:26405553

  11. DNA microarrays and likelihood ratio bioinformatic methods: discovery of human melanocyte biomarkers.

    PubMed

    Dooley, Thomas P; Curto, Ernest V; Davis, Richard L; Grammatico, Paola; Robinson, Edward S; Wilborn, Teresa W

    2003-06-01

    In this article, some of the advantages and limitations of DNA microarray technologies for gene expression profiling are summarized. As a model experiment, DermArray DNA microarrays were utilized to identify potential biomarkers of cultured normal human melanocytes in two different experimental comparisons. In the first case, melanocyte RNA was compared with vastly dissimilar non-melanocytic RNA samples of normal skin keratinocytes and fibroblasts. In the second case, melanocyte RNA was compared with a primary cutaneous melanoma line (MS7) and a metastatic melanoma cell line (SKMel-28). The alternative approaches provide dramatically different lists of 'normal melanocyte' biomarkers. The most robust biomarkers were identified using principal component analysis bioinformatic methods related to likelihood ratios. Only three of 25 robust biomarkers in the melanocyte-proximal study (i.e. melanocytes vs. melanoma cells) were coincidentally identified in the melanocyte-distal study (i.e. melanocytes vs. non-melanocytic cells). Selected up-regulated biomarkers of melanocytes (i.e. TRP-1, melan-A/MART-1, silver/Pmel17, and nidogen-2) were validated by qRT-PCR. Some of the melanocytic biomarkers identified here may be useful in molecular diagnostics, as potential molecular targets for drug discovery, and for understanding the biochemistry of melanocytic cells. PMID:12753397

  12. Suivi prospectif sur 5 ans des tentatives de suicide en population clinique dans la région de Fès, Maroc

    PubMed Central

    Aarab, Chadya; Elghazouani, Fatima; Aalouane, Rachid; Rammouz, Ismail

    2014-01-01

    Au Maroc, les tentatives de suicide (TS) demeurent un sujet mal évalué à cause de considérations socioculturelles et l'absence d'approche longitudinale. L'objectif principal était d’évaluer le devenir des suicidants après 5ans au centre universitaire psychiatrique de Fès, les objectifs secondaires étaient l'estimation de la prévalence des TS, préciser les étiologies les plus fréquentes, et établir une corrélation entre les paramètres sociodémographiques, cliniques et évolutifs. Etude prospective à visée transversale et longitudinale, incluant les suicidants vus à l'hôpital psychiatrique de Fès, avec un suivi longitudinal sur 5ans. L’évaluation a été faite par un hétéro-questionnaire et le Mini International Neuropsychiatric Interview (MINI) cherchant le trouble psychiatrique sous jacent. On a recruté 105 patients suicidants, 62% des femmes, l’âge moyen est de 29,23ans. La prévalence des tentatives de suicide est de 3% sur l'ensemble des consultants à l’établissement. Les troubles de l'humeur, psychotiques et de personnalité ont occupé respectivement 37,6%, 27,7%, et 25,7% des cas. La récidive suicidaire a été notée chez 54% des patients, était significativement corrélée à la vie solitaire (P: 0,039) et à la présence d'antécédents familiaux de TS (P: 0,046). L'utilisation de moyens violents était significativement fréquente chez les patients psychotiques. Après 5ans, 32 patients ont répondu à notre appel. Le taux de récidive était de 15%. On a noté trois cas de décès dont deux suicides confirmés. Les résultats confirment les données de la littérature scientifique avec certaines particularités cliniques et évolutives. PMID:25478042

  13. Lineage specific transcriptional regulation of DICER by MITF in melanocytes

    PubMed Central

    Levy, Carmit; Khaled, Mehdi; Robinson, Kathleen C.; Veguilla, Rosa A.; Chen, Po-Hao; Yokoyama, Satoru; Makino, Eiichi; Lu, Jun; Larue, Lionel; Beermann, Friedrich; Chin, Lynda; Bosenberg, Marcus; Song, Jun. S.; Fisher, David E.

    2010-01-01

    Summary DICER is a central regulator of microRNA maturation. However little is known about mechanisms regulating its expression in development or disease. While profiling miRNA expression in differentiating melanocytes, two populations were observed: some upregulated at the pre-miRNA stage, and others upregulated as “mature” miRNAs (with stable pre-miRNA levels). Conversion of pre-miRNAs to fully processed miRNAs appeared to be dependent upon stimulation of DICER expression—an event found to occur via direct transcriptional targeting of DICER by the melanocyte master transcriptional regulator MITF. MITF binds and activates a conserved regulatory element upstream of DICER’s transcriptional start site upon melanocyte differentiation. Targeted KO of DICER is lethal to melanocytes, at least partly via DICER-dependent processing of the pre-miRNA-17~92 cluster thus targeting BIM, a known pro-apoptotic regulator of melanocyte survival. These observations highlight a central mechanism underlying miRNA regulation which could exist for other cell types during development. PMID:20550935

  14. Hesperetin induces melanin production in adult human epidermal melanocytes.

    PubMed

    Usach, Iris; Taléns-Visconti, Raquel; Magraner-Pardo, Lorena; Peris, José-Esteban

    2015-06-01

    One of the major sources of flavonoids for humans are citrus fruits, hesperidin being the predominant flavonoid. Hesperetin (HSP), the aglycon of hesperidin, has been reported to provide health benefits such as antioxidant, anti-inflammatory and anticarcinogenic effects. However, the effect of HSP on skin pigmentation is not clear. Some authors have found that HSP induces melanogenesis in murine B16-F10 melanoma cells, which, if extrapolated to in vivo conditions, might protect skin against photodamage. Since the effect of HSP on normal melanocytes could be different to that observed on melanoma cells, the described effect of HSP on murine melanoma cells has been compared to the effect obtained using normal human melanocytes. HSP concentrations of 25 and 50 µM induced melanin synthesis and tyrosinase activity in human melanocytes in a concentration-dependent manner. Compared to control melanocytes, 25 µM HSP increased melanin production and tyrosinase activity 1.4-fold (p < 0.01) and 1.1-fold (p < 0.01), respectively, and the corresponding increases in the case of 50 µM HSP were 1.9-fold (p < 0.001) and 1.3-fold (p < 0.001). Therefore, HSP could be considered a valuable photoprotective substance if its capacity to increase melanin production in human melanocyte cultures could be reproduced on human skin. PMID:25765751

  15. Place de la laparoscopie dans la prise en charge des anomalies de différenciation sexuelle: à propos de 4 cas

    PubMed Central

    Goultaiene, Aissam; Elmortaji, Khalid; Sentissi, Reda; Moataz, Amine; Rabii, Redouane; Aboutaib, Rachid; Dakir, Mohammed; Debbagh, Adil; Meziane, Fethi

    2016-01-01

    Les troubles de la différenciation sexuelle sont à l'origine d'une discordance entre le sexe proprement dit (phénotypique) et le sexe génétique (génotypique) ce qui pose un problème de détermination du sexe. Dans les pays de faible niveau socio-économique où le diagnostic anténatal est souvent absent et les plateaux techniques insuffisants, la prise en charge médico-chirurgicale est difficile. Le but de ce travail est de préciser la place de la laparoscopie dans la prise en charge de l'ambiguïté sexuelle à travers l'observation de 4 cas et une revue de la littérature. PMID:27303583

  16. Characterization of two novel small molecules targeting melanocyte development in zebrafish embryogenesis.

    PubMed

    Chen, Lu; Ren, Xi; Liang, Fang; Li, Song; Zhong, Hanbing; Lin, Shuo

    2012-07-01

    Melanocytes are pigment cells that are closely associated with many skin disorders, such as vitiligo, piebaldism, Waardenburg syndrome, and the deadliest skin cancer, melanoma. Through studies of model organisms, the genetic regulatory network of melanocyte development during embryogenesis has been well established. This network also seems to be shared with adult melanocyte regeneration and melanoma formation. To identify chemical regulators of melanocyte development and homeostasis, we screened a small-molecule library of 6000 compounds using zebrafish embryos and identified five novel compounds that inhibited pigmentation. Here we report characterization of two compounds, 12G9 and 36E9, which disrupted melanocyte development. TUNEL assay indicated that these two compounds induced apoptosis of melanocytes. Furthermore, compound 12G9 specifically inhibited the viability of mammalian melanoma cells in vitro. These two compounds should be useful as chemical biology tools to study melanocytes and could serve as drug candidates against melanocyte-related diseases. PMID:22574862

  17. Wnt inhibitory factor (WIF)-1 promotes melanogenesis in normal human melanocytes.

    PubMed

    Park, Tae Jun; Kim, Misun; Kim, Hyeran; Park, Sun Yi; Park, Kyoung-Chan; Ortonne, Jean-Paul; Kang, Hee Young

    2014-01-01

    Wnt signaling plays a role in the differentiation as well as the development of melanocytes. Using a microarray analysis, hyperpigmentary skin of melasma expressed high levels of Wnt inhibitory factor-1 (WIF-1) compared with perilesional normal skin. In this study, the expression and functional roles of WIF-1 on melanocytes were investigated. WIF-1 was expressed both in the melanocytes of normal human skin and in cultured melanocytes. The upregulation of WIF-1 on cultured normal human melanocytes significantly induced expressions of MITF and tyrosinase, which were associated with increased melanin content and tyrosinase activity. Consistent with the stimulatory effect of WIF-1, WIF-1 siRNA reduced melanogenesis in the cells. Moreover, WIF-1 increases pigmentation in melanocytes co-cultured with WIF-1-overexpressed fibroblasts and of organ-cultured human skin. These findings suggest that melanocytes express WIF-1 constitutively in vivo and in vitro and that WIF-1 promotes melanogenesis in normal human melanocytes. PMID:24131586

  18. Détermination des paramètres bioécologiques et entomologiques d’Anopheles gambiae sl dans la transmission du paludisme à Bandundu-ville, République Démocratique de Congo

    PubMed Central

    Matubi, Emery Metelo; Bukaka, Eric; Luemba, Trésor Bakambana; Situakibanza, Hyppolite; Sangaré, Ibrahim; Mesia, Gauthier; Ngoyi, Dieudonné Mumba; Maniania, Nguya Kalemba; Akikwa, Charles Ngandote; Kanza, Jean Pierre Basilua; Tamfum, Jean-Jacques Muyembe; sudi, Jonas Nagahuedi Bongo

    2015-01-01

    Introduction La présente étude a été menée à Bandundu-ville (RDC) en vue d'identifier les paramètres écologiques et entomologiques modulant la transmission du paludisme ainsi que leur tendance saisonnière dans cette agglomération. Méthodes Cette étude a été réalisée dans la période du 1er juin au 31 décembre 2011. Des prospections des gîtes larvaires d'anophèles avec récolte ont été réalisées, les paramètres physiques, physico-chimiques et environnementaux déterminés. La densité larvaire a été estimée selon une échelle de classes de densité, inspirée de la méthode de Carron pour chaque type de gîtes. Quarante-huit maisons ont été sélectionnées et prospectées pour la récolte des moustiques par pulvérisation intradomicilaire. L'identification des moustiques a été faite sur base des critères morphologiques de Gilles et Demeillon. L'Indice sporozoïtique (Is) a été déterminé par le test ELISA CSP de Plasmodium falciparum à l'Institut National de Recherche Biomédicale selon le protocole de Robert Wirtz. Les autres paramètres entomologiques comme la densité, le taux d'agressivité, le taux d'inoculation entomologique (TIE) ainsi que l'indice de stabilité ont été déterminés selon le protocole de l'OMS. La régression linéaire a été réalisée au seuil de signification de 0,05 pour identifier les déterminants de la densité larvaire. Résultats Cent-sept gîtes larvaires ont été identifiés et caractérisés en 5 types (digues et puits d'eau, collections d'eau maraîchère et concasseurs moellons, marais Régie de distribution d'eau, marais le long des rivières et ruisseaux et flaques d'eau de pluies). La densité larvaire moyenne a été de 117,4±64,1. Quatre mille cinq cents quatre-vingt-huit moustiques ont été capturés et identifiés, parmi lesquels 1.258 Anopheles gambiae sl avec une densité de 8,86, un taux d'agressivité de 1,55 piqûre par homme par nuit, l'Is de 5,6%, un TIE de 0,085 piq

  19. Analyse des facteurs histo-pronostiques du cancer du rectum non métastatique dans une série ouest Algérienne de 58 cas au CHU-Tlemcen

    PubMed Central

    Mesli, Smain Nabil; Regagba, Derbali; Tidjane, Anisse; Benkalfat, Mokhtar; Abi-Ayad, Chakib

    2016-01-01

    Introduction L'objectif de notre travail est d'analyser les facteurs histo-pronostiques des cancers du rectum non métastatique opérés au service de chirurgie «A» de Tlemcen à ouest Algérien durant une période de six ans. Méthodes Etude rétrospective de 58 patients qui avait un adénocarcinome rectal. Le critère de jugement était la survie. Les paramètres étudiés, le sexe, l’âge, stade tumoral, et les récidives tumorales. Résultats L’âge moyen était de 58 ans. Avec 52% d'hommes contre 48% femmes avec sex-ratio (1,08). Le siège tumoral était: moyen rectum avec 41,37%, 34,48% au bas rectum et dans 24,13% au haut rectum. La classification TNM avec 17,65% au stade I, 18,61% au stade II, 53, 44% au stade III et 7,84% au stade IV. La survie médiane globale était de 40 mois ±2,937 mois. La survie en fonction du stade tumoral, le stade III et IV avait un faible taux de survie (19%) a 3 ans contre le stade I, II avait un taux de survie de (75%) (P = 0,000) (IC 95%). Les patients avec récidives tumorales avaient un taux de survie faible à 3 ans par rapport à ceux n'ayant pas eu de récidive (30,85% Vs 64,30% P = 0,043). Conclusion Dans cette série, l’étude uni varié des différents facteurs pronostiques conditionnant la survie n'a permis de retenir que trois facteurs influençant la survie, à savoir la taille tumorale, le stade, et les récidives tumorales. En analyse multi variée en utilisant le modèle Cox un seul facteur été retenu la récidive tumorale.

  20. Induction of nerve growth factor receptors on cultured human melanocytes

    SciTech Connect

    Peacocke, M.; Yaar, M.; Mansur, C.P.; Chao, M.V.; Gilchrest, B.A. )

    1988-07-01

    Normal differentiation and malignant transformation of human melanocytes involve a complex series of interactions during which both genetic and environmental factors play roles. At present, the regulation of these processes is poorly understood. The authors have induced the expression of nerve growth factor (NGF) receptors on cultured human melanocytes with phorbol 12-tetradecanoate 13-acetate and have correlated this event with the appearance of a more differentiated, dendritic morphology. Criteria for NGF receptor expression included protein accumulation and cell-surface immunofluorescent staining with a monoclonal antibody directed against the human receptor and induction of the messenger RNA species as determined by blot-hybridization studies. The presence of the receptor could also be induced by UV irradiation or growth factor deprivation. The NGF receptor is inducible in cultured human melanocytes, and they suggest that NGF may modulate the behavior of this neural crest-derived cell in the skin.

  1. Multiple roles of NF1 in the melanocyte lineage.

    PubMed

    Larribère, Lionel; Utikal, Jochen

    2016-07-01

    NF1 is a tumour suppressor gene, germline mutations of which lead to neurofibromatosis type 1 syndrome. Patients develop benign tumours from several types of cells including neural crest-derived cells. NF1 somatic mutations also occur in 15% of sporadic melanoma, a cancer originating from melanocytes. Evidence now suggests the involvement of NF1 mutations in melanoma resistance to targeted therapies. Although NF1 is ubiquitously expressed, genetic links between NF1 and genes involved in melanocyte biology have been described, implying the lineage-specific mechanisms. In this review, we summarize and discuss the latest advances related to the roles of NF1 in melanocyte biology and in cutaneous melanoma. PMID:27155159

  2. Fibronectin-Containing Extracellular Vesicles Protect Melanocytes against Ultraviolet Radiation-Induced Cytotoxicity.

    PubMed

    Bin, Bum-Ho; Kim, Dae-Kyum; Kim, Nan-Hyung; Choi, Eun-Jeong; Bhin, Jinhyuk; Kim, Sung Tae; Gho, Yong Song; Lee, Ai-Young; Lee, Tae Ryong; Cho, Eun-Gyung

    2016-05-01

    Skin melanocytes are activated by exposure to UV radiation to secrete melanin-containing melanosomes to protect the skin from UV-induced damage. Despite the continuous renewal of the epidermis, the turnover rate of melanocytes is very slow, and they survive for long periods. However, the mechanisms underlying the survival of melanocytes exposed to UV radiation are not known. Here, we investigated the role of melanocyte-derived extracellular vesicles in melanocyte survival. Network analysis of the melanocyte extracellular vesicle proteome identified the extracellular matrix component fibronectin at a central node, and the release of fibronectin-containing extracellular vesicles was increased after exposure of melanocytes to UVB radiation. Using an anti-fibronectin neutralizing antibody and specific inhibitors of extracellular vesicle secretion, we demonstrated that extracellular vesicles enriched in fibronectin were involved in melanocyte survival after UVB radiation. Furthermore, we observed that in the hyperpigmented lesions of patients with melasma, the extracellular space around melanocytes contained more fibronectin compared with normal skin, suggesting that fibronectin is involved in maintaining melanocytes in pathological conditions. Collectively, our findings suggest that melanocytes secrete fibronectin-containing extracellular vesicles to increase their survival after UVB radiation. These data provide important insight into how constantly stimulated melanocytes can be maintained in pathological conditions such as melasma. PMID:26854492

  3. Etude du processus de changement vecu par des familles ayant decide d'adopter volontairement des comportements d'attenuation des changements climatiques

    NASA Astrophysics Data System (ADS)

    Leger, Michel T.

    Les activites humaines energivores telles l'utilisation intensive de l'automobile, la surconsommation de biens et l'usage excessif d'electricite contribuent aux changements climatiques et autres problemes environnementaux. Bien que plusieurs recherches rapportent que l'etre humain est de plus en plus conscient de ses impacts sur le climat de la planete, ces memes recherches indiquent qu'en general, les gens continuent a se comporter de facon non ecologique. Que ce soit a l'ecole ou dans la communaute, plusieurs chercheurs en education relative a l'environnement estiment qu'une personne bien intentionnee est capable d'adopter des comportements plus respectueux de l'environnement. Le but de cette these etait de comprendre le processus d'integration de comportements d'attenuation des changements climatiques dans des familles. A cette fin, nous nous sommes fixe deux objectifs : 1) decrire les competences et les procedes qui favorisent l'adoption de comportements d'attenuation des changements climatiques dans des familles et 2) decrire les facteurs et les dynamiques familiales qui facilitent et limitent l'adoption de comportements d'attenuation des changements climatiques dans des familles. Des familles ont ete invitees a essayer des comportements personnels et collectifs d'attenuation des changements climatiques de sorte a integrer des modes de vie plus ecologiques. Sur une periode de huit mois, nous avons suivi leur experience de changement afin de mieux comprendre comment se produit le processus de changement dans des familles qui decident volontairement d'adopter des comportements d'attenuation des changements climatiques. Apres leur avoir fourni quelques connaissances de base sur les changements climatiques, nous avons observe le vecu de changement des familles durant huit mois d'essais a l'aide de journaux reflexifs, d'entretiens d'explicitation et du journal du chercheur. La these comporte trois articles scientifiques. Dans le premier article, nous presentons une

  4. Amelanotic Melanoma in the Vicinity of Acquired Melanocytic Nevi and not Arising from Agminated Melanocytic Nevi: Masquerading as Pyogenic Granuloma

    PubMed Central

    Rao, Angoori Gnaneshwar; Babu, V Ashok; Koppada, Divya; Haritha, M; Chandana, P; Swapna; Anoosha

    2016-01-01

    Amelanotic melanoma (AMM) presenting as pyogenic granuloma and occurring in the vicinity of acquired melanocytic nevi is rare. Herein, we report such a manifestation in a 68-year-old male who presented with the painful red nodule and multiple pigmented patches involving the left great toe. Histopathological examination of skin biopsy taken from the nodule with an immunohistochemical study using HMB45 and S-100 confirmed the diagnosis of AMM. Biopsy from the pigmented patch near the nodule showed features of melanocytic nevus. Investigative work up revealed metastatic deposits in the left inguinal lymph node with no evidence of systemic involvement, placing him in malignant melanoma Stage IIIC of American Joint Committee on Cancer (AJCC) tumor node metastasis system. The development of AMM in the vicinity of acquired melanocytic nevi and manifesting as granuloma pyogenicum is unique in this case. PMID:26955141

  5. La prise en charge à long terme de l’asthme chez les enfants inuits et des Premières nations : un outil de transfert du savoir fondé sur les lignes directrices canadiennes pour l’asthme pédiatrique, conçu pour être utilisé par les professionnels de la santé de première ligne qui travaillent dans des communautés isolées

    PubMed Central

    Kovesi, Tom; Giles, Brenda Louise; Pasterkamp, Hans

    L’asthme est un grave problème de santé pour les enfants inuits et des Premières nations. Chez les enfants de moins d’un an, il faut distinguer l’asthme de la bronchiolite virale, anormalement fréquente chez les enfants autochtones du Canada. Chez les enfants de moins de six ans, le diagnostic dépend de la présence de symptômes classiques, de l’absence de caractéristiques atypiques et de la consignation de la réponse au traitement, notamment la réponse rapide et transitoire aux bronchodilatateurs. Chez les enfants plus âgés, il faut, dans la mesure du possible, déterminer la présence d’une obstruction réversible des voies aériennes par spirométrie afin de confirmer le diagnostic, ainsi qu’évaluer et corriger les déclencheurs environnementaux. L’utilisation régulière de corticoïdes en aérosol est la principale mesure à prendre pour maintenir un bon contrôle de l’asthme chez les enfants asthmatiques. Les clients et leur famille devraient recevoir une formation sur l’asthme. Il faut réévaluer régulièrement le contrôle aux visites de suivi dans des centres de santé et rajuster le traitement à la dose la plus basse possible pour le maintien de ce contrôle.

  6. Traumatic iridial extrusion mimicking a conjunctival melanocytic neoplasm

    PubMed Central

    Zoroquiain, Pablo; Ganimi, Maria SB; Alghamdi, Sarah; Burnier, Julia V; Aldrees, Sultan S; Burnier, Miguel N

    2016-01-01

    Conjunctival melanoma is a rare malignant tumour of the eye. Its diagnosis represents a challenge for general pathologists due to low exposure to ocular biopsies and a broad differential diagnosis. In addition, conjunctival samples are often small and are associated with a high frequency of artefacts due to their processing. Here, we present the first case to date of a traumatic iridial extrusion masquerading as a conjunctival melanocytic neoplasm. An 83-year-old Asian man presented with a conjunctival-pigmented nodule surrounded by an area of diffuse pigmentation. Histopathology revealed in the nodule a well-demarcated lesion composed of spindle shaped melanocytes with thick-walled blood vessels. At higher magnification, the blood vessels were composed of thick walls with collagen fibres in an onion-skin-like arrangement. The histological findings were consistent with extruded iridial tissue. The map biopsies of the flat, pigmented lesion showed melanocytic cell proliferation with dendritic processes restricted to the lamina propria without any epithelial involvement, consistent with ocular melanocytosis. The diagnosis of conjunctival melanocytic lesions is challenging, and non-neoplastic conditions should always be included in the differential diagnosis. Pathologists should correlate clinicopathological findings and be familiar with the normal histology in order to achieve the correct diagnosis. PMID:26913071

  7. The melanocyte differentiation program predisposes to metastasis following neoplastic transformation.

    PubMed Central

    Gupta, Piyush B.; Kuperwasser, Charlotte; Brunet, Jean-Philippe; Ramaswamy, Sridhar; Kuo, Wen-Lin; Gray, Joe W.; Naber, Stephen P.; Weinberg, Robert A.

    2006-01-01

    The aggressive clinical behavior of melanoma has led to the hypothesis that the developmental origins of melanocytes in the neural crest might be relevant for their metastatic propensity. We demonstrate that primary human melanocytes, transformed using a specific set of introduced genes, form melanomas that frequently metastasize to multiple secondary sites, while human fibroblasts and epithelial cells transformed using an identical set of genes generate primary tumors that rarely do so. Importantly, these melanomas exhibit a metastasis spectrum similar to that observed in human patients. These observations indicate that part of the metastatic proclivity of melanoma is attributable to lineage-specific factors expressed in melanocytes and not in other cell types analyzed. Analysis of microarray data from human nevi reveals that Slug, a master regulator of neural crest cell specification and migration, correlates in its expression pattern with other genes that are important for neural crest cell migrations during development. Moreover, Slug is required for the metastasis of the transformed melanoma cells. These findings indicate that melanocyte-specific factors present prior to neoplastic transformation can play a pivotal role in governing melanoma's progression. PMID:16142232

  8. Traumatic iridial extrusion mimicking a conjunctival melanocytic neoplasm.

    PubMed

    Zoroquiain, Pablo; Ganimi, Maria Sb; Alghamdi, Sarah; Burnier, Julia V; Aldrees, Sultan S; Burnier, Miguel N

    2016-01-01

    Conjunctival melanoma is a rare malignant tumour of the eye. Its diagnosis represents a challenge for general pathologists due to low exposure to ocular biopsies and a broad differential diagnosis. In addition, conjunctival samples are often small and are associated with a high frequency of artefacts due to their processing. Here, we present the first case to date of a traumatic iridial extrusion masquerading as a conjunctival melanocytic neoplasm. An 83-year-old Asian man presented with a conjunctival-pigmented nodule surrounded by an area of diffuse pigmentation. Histopathology revealed in the nodule a well-demarcated lesion composed of spindle shaped melanocytes with thick-walled blood vessels. At higher magnification, the blood vessels were composed of thick walls with collagen fibres in an onion-skin-like arrangement. The histological findings were consistent with extruded iridial tissue. The map biopsies of the flat, pigmented lesion showed melanocytic cell proliferation with dendritic processes restricted to the lamina propria without any epithelial involvement, consistent with ocular melanocytosis. The diagnosis of conjunctival melanocytic lesions is challenging, and non-neoplastic conditions should always be included in the differential diagnosis. Pathologists should correlate clinicopathological findings and be familiar with the normal histology in order to achieve the correct diagnosis. PMID:26913071

  9. Genome-wide transcriptome analysis of human epidermal melanocytes

    PubMed Central

    Haltaufderhyde, Kirk D.; Oancea, Elena

    2015-01-01

    Because human epidermal melanocytes (HEMs) provide critical protection against skin cancer, sunburn, and photoaging, a genome-wide perspective of gene expression in these cells is vital to understanding human skin physiology. In this study we performed high throughput sequencing of HEMs to obtain a complete data set of transcript sizes, abundances, and splicing. As expected, we found that melanocyte specific genes that function in pigmentation were among the highest expressed genes. We analyzed receptor, ion channel and transcription factor gene families to get a better understanding of the cell signalling pathways used by melanocytes. We also performed a comparative transcriptomic analysis of lightly versus darkly pigmented HEMs and found 16 genes differentially expressed in the two pigmentation phenotypes; of those, only one putative melanosomal transporter (SLC45A2) has known function in pigmentation. In addition, we found 166 genes with splice isoforms expressed exclusively in one pigmentation phenotype, 17 of which are genes involved in signal transduction. Our melanocyte transcriptome study provides a comprehensive view and may help identify novel pigmentation genes and potential pharmacological targets. PMID:25451175

  10. Effets des electrons secondaires sur l'ADN

    NASA Astrophysics Data System (ADS)

    Boudaiffa, Badia

    Les interactions des electrons de basse energie (EBE) representent un element important en sciences des radiations, particulierement, les sequences se produisant immediatement apres l'interaction de la radiation ionisante avec le milieu biologique. Il est bien connu que lorsque ces radiations deposent leur energie dans la cellule, elles produisent un grand nombre d'electrons secondaires (4 x 104/MeV), qui sont crees le long de la trace avec des energies cinetiques initiales bien inferieures a 20 eV. Cependant, il n'y a jamais eu de mesures directes demontrant l'interaction de ces electrons de tres basse energie avec l'ADN, du principalement aux difficultes experimentales imposees par la complexite du milieu biologique. Dans notre laboratoire, les dernieres annees ont ete consacrees a l'etude des phenomenes fondamentaux induits par impact des EBE sur differentes molecules simples (e.g., N2, CO, O2, H2O, NO, C2H 4, C6H6, C2H12) et quelques molecules complexes dans leur phase solide. D'autres travaux effectues recemment sur des bases de l'ADN et des oligonucleotides ont montre que les EBE produisent des bris moleculaires sur les biomolecules. Ces travaux nous ont permis d'elaborer des techniques pour mettre en evidence et comprendre les interactions fondamentales des EBE avec des molecules d'interet biologique, afin d'atteindre notre objectif majeur d'etudier l'effet direct de ces particules sur la molecule d'ADN. Les techniques de sciences des surfaces developpees et utilisees dans les etudes precitees peuvent etre etendues et combinees avec des methodes classiques de biologie pour etudier les dommages de l'ADN induits par l'impact des EBE. Nos experiences ont montre l'efficacite des electrons de 3--20 eV a induire des coupures simple et double brins dans l'ADN. Pour des energies inferieures a 15 eV, ces coupures sont induites par la localisation temporaire d'un electron sur une unite moleculaire de l'ADN, ce qui engendre la formation d'un ion negatif transitoire

  11. Adipose-Derived Stem Cells Improve Efficacy of Melanocyte Transplantation in Animal Skin

    PubMed Central

    Lim, Won-Suk; Kim, Chang-Hyun; Kim, Ji-Young; Do, Byung-Rok; Kim, Eo Jin; Lee, Ai-Young

    2014-01-01

    Vitiligo is a pigmentary disorder induced by a loss of melanocytes. In addition to replacement of pure melanocytes, cocultures of melanocytes with keratinocytes have been used to improve the repigmentation outcome in vitiligo treatment. We previously identified by in vitro studies, that adipose-derived stem cells (ADSCs) could be a potential substitute for keratinocytes in cocultures with melanocytes. In this study, the efficacy of pigmentation including durability of grafted melanocytes and short-term safety was examined in the nude mouse and Sprague-Dawley rat after grafting of primary cultured human melanocytes, with or without different ratios of primary cultured human ADSCs. Simultaneous grafting of melanocytes and ADSCs, which were separately cultured and mixed on grafting at the ratios of 1:1, 1:2, or 1:3, showed better efficacy than that of pure melanocytes. Grafting of melanocytes cocultured with ADSCs resulted in a similar outcome as the grafting of cell mixtures. Skin pigmentation by melanocytes : ADSCs at the ratios of 1:1 and 1:2 was better than at 1:3. No significant difference was observed between the 1-week and 2-week durations in coculturing. Time-course microscopic examination showed that the grafted melanocytes remained a little longer than 6-week post-grafting. No inflammatory cell infiltration was observed in the grafted skin and no melanocytes were detectable in other organs. Collectively, grafting of melanocytes and ADSCs was equally safe and more effective than grafting of melanocytes alone. Despite the absence of significant differences in efficacy between the group of 1:1 and that of 1:2 ratio, 1:2 ratio for 1-week coculturing may be better for clinical use from the cost-benefit viewpoint. PMID:25143812

  12. Optimal management of common acquired melanocytic nevi (moles): current perspectives

    PubMed Central

    Sardana, Kabir; Chakravarty, Payal; Goel, Khushbu

    2014-01-01

    Although common acquired melanocytic nevi are largely benign, they are probably one of the most common indications for cosmetic surgery encountered by dermatologists. With recent advances, noninvasive tools can largely determine the potential for malignancy, although they cannot supplant histology. Although surgical shave excision with its myriad modifications has been in vogue for decades, the lack of an adequate histological sample, the largely blind nature of the procedure, and the possibility of recurrence are persisting issues. Pigment-specific lasers were initially used in the Q-switched mode, which was based on the thermal relaxation time of the melanocyte (size 7 μm; 1 μsec), which is not the primary target in melanocytic nevus. The cluster of nevus cells (100 μm) probably lends itself to treatment with a millisecond laser rather than a nanosecond laser. Thus, normal mode pigment-specific lasers and pulsed ablative lasers (CO2/erbium [Er]:yttrium aluminum garnet [YAG]) are more suited to treat acquired melanocytic nevi. The complexities of treating this disorder can be overcome by following a structured approach by using lasers that achieve the appropriate depth to treat the three subtypes of nevi: junctional, compound, and dermal. Thus, junctional nevi respond to Q-switched/normal mode pigment lasers, where for the compound and dermal nevi, pulsed ablative laser (CO2/Er:YAG) may be needed. If surgical excision is employed, a wide margin and proper depth must be ensured, which is skill dependent. A lifelong follow-up for recurrence and melanoma is warranted in predisposed individuals, although melanoma is decidedly uncommon in most acquired melanocytic nevi, even though histological markers may be seen on evaluation. PMID:24672253

  13. Digital dermoscopic follow-up of 1544 melanocytic nevi.

    PubMed

    Rotaru, Maria; Nati, Angelica-Elena; Avrămoiu, Ioan; Grosu, Florin; Mălăescu, Gheorghe Dan

    2015-01-01

    The use of dermatoscopy increases melanocytic nevi diagnostic accuracy, and is important for dermoscopic monitoring of atypical lesions, allowing to find significant changes in the earliest stage. Dermoscopic diagnosis of melanocytic nevi type in a group of patients and their follow-up with the assessment of changes occurred during dermoscopic monitoring. Dermoscopically, we followed the nevic size and pattern, the color and pigment distribution. Follow-up visits were scheduled depending on the type of the melanocytic lesions and the patient's compliance. The nevi that have shown significant dermoscopic changes were excised and histopathologically examined. The study was performed on a group of 92 patients, mostly females (56.5%), mean age of 29.1 years. Of the total of 1544 melanocytic nevi examined, 27.4% were atypical and 72.6% common nevi. The average dermoscopic examination interval was 14.1 months. During monitoring, 35.5% atypical nevi and 22.5% common nevi have modified, especially changes in pigmentation and color (31% atypical nevi and 9.9% common nevi) and the appearance of new dermoscopic structures (12.7% atypical nevi and common nevi 8.5%). Of the total nevi monitored, 3% showed significant changes and were excised and examined pathologically, without diagnose of any malignant transformation. In our study, dermoscopic changes appeared in atypical as well as in common nevi. The dermoscopic monitoring of melanocytic-pigmented lesions remains an accessible method of assessment the evolution of nevi and can reduce the risk of appearance of malignant melanoma in the general population. PMID:26743296

  14. Optimal management of common acquired melanocytic nevi (moles): current perspectives.

    PubMed

    Sardana, Kabir; Chakravarty, Payal; Goel, Khushbu

    2014-01-01

    Although common acquired melanocytic nevi are largely benign, they are probably one of the most common indications for cosmetic surgery encountered by dermatologists. With recent advances, noninvasive tools can largely determine the potential for malignancy, although they cannot supplant histology. Although surgical shave excision with its myriad modifications has been in vogue for decades, the lack of an adequate histological sample, the largely blind nature of the procedure, and the possibility of recurrence are persisting issues. Pigment-specific lasers were initially used in the Q-switched mode, which was based on the thermal relaxation time of the melanocyte (size 7 μm; 1 μsec), which is not the primary target in melanocytic nevus. The cluster of nevus cells (100 μm) probably lends itself to treatment with a millisecond laser rather than a nanosecond laser. Thus, normal mode pigment-specific lasers and pulsed ablative lasers (CO2/erbium [Er]:yttrium aluminum garnet [YAG]) are more suited to treat acquired melanocytic nevi. The complexities of treating this disorder can be overcome by following a structured approach by using lasers that achieve the appropriate depth to treat the three subtypes of nevi: junctional, compound, and dermal. Thus, junctional nevi respond to Q-switched/normal mode pigment lasers, where for the compound and dermal nevi, pulsed ablative laser (CO2/Er:YAG) may be needed. If surgical excision is employed, a wide margin and proper depth must be ensured, which is skill dependent. A lifelong follow-up for recurrence and melanoma is warranted in predisposed individuals, although melanoma is decidedly uncommon in most acquired melanocytic nevi, even though histological markers may be seen on evaluation. PMID:24672253

  15. Modification et caractérisation de la surface de fibres de verre pour son insertion postérieure dans des matériaux cimentaires

    NASA Astrophysics Data System (ADS)

    Bismarck, A.; Ajuriagojeaskoa, E. E.; Springer, J.; Habel, W. R.

    1999-07-01

    Optical fibres are widely used as physical and mechanical sensors in various matrices. Those commercial available fibres are mostly coated with different polymers (e.g. polyimide). The problem of using such coatings is the undefined adhesion and the stress transmission from the matrix material into the fibre as well as the alkaline attack from the cementitious environments onto the glass surface. Therefore the known silanisation process with alkylsilanes for surface modification was studied. To achieve a silane film onto the fibre surface as close as possible a fibre pre-treatment in oxygen plasma was applied. The wetting behaviour of the oxygen plasma treated fibres as well as the silanized fibres were studied using the Wilhelmy-method. The influence of the silane concentration and the time of the pre-treatment on the wetting properties was investigated. By scanning electron microscopy, changes of the surface morphology were detected. Additionally, the mechanical properties of the oxygen plasma treated fibres, and silanized fibres exposed to a highly alkaline pore solution were measured. For selected fibre samples (decoated and untreated as well as silanized fibres) the adhesion to a concrete matrix was studied using the indention test. Les fibres optiques sont de plus en plus utilisées comme capteurs des propriétés physiques et mécaniques de nombreuses matrices. Ces fibres commerciales sont généralement enrobées avec différents polymères (par exemple polyimide). Les problèmes dus à l'enrobage des fibres optiques sont une adhésion et une transmission de charge de la matrice du béton à la fibre non définies. Un autre problème majeur est l'alcalinité du béton et son influence sur la surface de la fibre. Nous avons utilisé le procédé de silanisation. Pour obtenir un film de silane le plus homogène possible sur la surface, les fibres sont pré-traitées par le plasma d?oxygène. Le mouillage de fibres traitées par le plasma d?oxygène, ainsi que

  16. Melanocytes Affect Nodal Expression and Signaling in Melanoma Cells: A Lesson from Pediatric Large Congenital Melanocytic Nevi

    PubMed Central

    Margaryan, Naira V.; Gilgur, Alina; Seftor, Elisabeth A.; Purnell, Chad; Arva, Nicoleta C.; Gosain, Arun K.; Hendrix, Mary J. C.; Strizzi, Luigi

    2016-01-01

    Expression of Nodal, a Transforming Growth Factor-beta (TGF-β) related growth factor, is associated with aggressive melanoma. Nodal expression in adult dysplastic nevi may predict the development of aggressive melanoma in some patients. A subset of pediatric patients diagnosed with giant or large congenital melanocytic nevi (LCMN) has shown increased risk for development of melanoma. Here, we investigate whether Nodal expression can help identify the rare cases of LCMN that develop melanoma and shed light on why the majority of these patients do not. Immunohistochemistry (IHC) staining results show varying degree of Nodal expression in pediatric dysplastic nevi and LCMN. Moreover, median scores from Nodal IHC expression analysis were not significantly different between these two groups. Additionally, none of the LCMN patients in this study developed melanoma, regardless of Nodal IHC levels. Co-culture experiments revealed reduced tumor growth and lower levels of Nodal and its signaling molecules P-SMAD2 and P-ERK1/2 when melanoma cells were grown in vivo or in vitro with normal melanocytes. The same was observed in melanoma cells cultured with melanocyte conditioned media containing pigmented melanocyte derived melanosomes (MDM). Since MDM contain molecules capable of inactivating radical oxygen species, to investigate potential anti-oxidant effect of MDM on Nodal expression and signaling in melanoma, melanoma cells were treated with either N-acetyl-l-cysteine (NAC), a component of the anti-oxidant glutathione or synthetic melanin, which in addition to providing pigmentation can also exert free radical scavenging activity. Melanoma cells treated with NAC or synthetic melanin showed reduced levels of Nodal, P-SMAD2 and P-ERK1/2 compared to untreated melanoma cells. Thus, the potential role for Nodal in melanoma development in LCMN is less evident than in adult dysplastic nevi possibly due to melanocyte cross-talk in LCMN capable of offsetting or delaying the pro

  17. Melanocytes Affect Nodal Expression and Signaling in Melanoma Cells: A Lesson from Pediatric Large Congenital Melanocytic Nevi.

    PubMed

    Margaryan, Naira V; Gilgur, Alina; Seftor, Elisabeth A; Purnell, Chad; Arva, Nicoleta C; Gosain, Arun K; Hendrix, Mary J C; Strizzi, Luigi

    2016-01-01

    Expression of Nodal, a Transforming Growth Factor-beta (TGF-β) related growth factor, is associated with aggressive melanoma. Nodal expression in adult dysplastic nevi may predict the development of aggressive melanoma in some patients. A subset of pediatric patients diagnosed with giant or large congenital melanocytic nevi (LCMN) has shown increased risk for development of melanoma. Here, we investigate whether Nodal expression can help identify the rare cases of LCMN that develop melanoma and shed light on why the majority of these patients do not. Immunohistochemistry (IHC) staining results show varying degree of Nodal expression in pediatric dysplastic nevi and LCMN. Moreover, median scores from Nodal IHC expression analysis were not significantly different between these two groups. Additionally, none of the LCMN patients in this study developed melanoma, regardless of Nodal IHC levels. Co-culture experiments revealed reduced tumor growth and lower levels of Nodal and its signaling molecules P-SMAD2 and P-ERK1/2 when melanoma cells were grown in vivo or in vitro with normal melanocytes. The same was observed in melanoma cells cultured with melanocyte conditioned media containing pigmented melanocyte derived melanosomes (MDM). Since MDM contain molecules capable of inactivating radical oxygen species, to investigate potential anti-oxidant effect of MDM on Nodal expression and signaling in melanoma, melanoma cells were treated with either N-acetyl-l-cysteine (NAC), a component of the anti-oxidant glutathione or synthetic melanin, which in addition to providing pigmentation can also exert free radical scavenging activity. Melanoma cells treated with NAC or synthetic melanin showed reduced levels of Nodal, P-SMAD2 and P-ERK1/2 compared to untreated melanoma cells. Thus, the potential role for Nodal in melanoma development in LCMN is less evident than in adult dysplastic nevi possibly due to melanocyte cross-talk in LCMN capable of offsetting or delaying the pro

  18. Diffusion des Metaux et Evolution Stellaire

    NASA Astrophysics Data System (ADS)

    Turcotte, Sylvain

    Nous presentons dans cette these des modeles d'evolution stellaire incorporant la diffusion microscopique de maniere consistante. Pour la premiere fois, on a calcule l'evolution d'etoiles en tenant compte en detail de l'impact des variations d'abondances sur leur structure. Nous utilisons des spectres monochromatiques pour chacun des elements les plus abondants dans un melange solaire pour recalculer l'opacite pour les abondances et les conditions locales dans l'interieur d'une etoile au cours de son evolution. Nos modeles montrent que la diffusion atomique des metaux a un effet important sur les opacites dan les etoiles de plus de 1.3Msolar ou l'abondance du fer et des autres elements du pic du fer varient substantiellement. Ces etoiles, sans rotation ou champ magnetique, sont proches des etoiles de type Fm-Am dans lesquelles on observe une legere surabondance d'elements du pic du fer en plus d'une sous-abondance de calcium, sous-abondance que l'on obtient egalement. Nous obtenons cependant des surabondances depassant un facteur 10 pour les etoiles de plus de 1.4Msolar ce qui suggere qu'il existe un ou plusieurs mecanismes limitant la diffusion microscopique. La surabondance du fer en surface cause une augmentation, qui peut atteindre un facteur sept, de l'opacite a la limite de la zone convective. Ceci cause un accroissement de la temperature effective et de la masse de la zone convective comparativement aux modeles n'incluant que la diffusion de l'helium. Il s'agit la du principal effet de la diffusion sur la structure interne de ces etoiles. La diffusions n'a pas d'influence sur l'evolution de coeur stellaire dans les etoiles significativement plus massives quie le Soleil. Nous avons verife que l'utilisation de modeles consistants avec diffusion n'apporte pas d'amelioration sensible aux modeles solaires. Les forces radiatives calculees a partir des spectres d'OPAL pour les elements du pic du fer representent une fraction importante de la gravite. On obtient des

  19. Lambeau Expanse du Cuir Chevelu dans la Couverture des Alopecies Cicatricielles sur Sequelles de Brulures. A Propos d'une Observation

    PubMed Central

    El Mazouz, S.; Hafidi, J.; Fejjal, N.; Mejjati, H.; Cherkab, L.; Gharib, N.; Abbassi, A.

    2010-01-01

    Summary Les séquelles esthétiques des alopécies cicatricielles sur séquelles de brûlures sont responsables de préjudices empêchant parfois la réinsertion sociale du patient, surtout chez les sujets de sexe féminin. Le cuir chevelu permet la réalisation de lambeaux permettant de couvrir ces alopécies. Les Auteurs décrivent le cas d'une jeune patiente victime d'une alopécie cicatricielle sur séquelles de brûlures chez qui ils ont réalisé un lambeau expansé du cuir chevelu et mettent le point sur la prise en charge de ces lésions à travers ce cas clinique et une revue de littérature. PMID:21991195

  20. Apport de l’écho-doppler artériel des membres inférieurs dans la prise en charge du pied diabétique à l'hôpital Saint-Jean de Dieu de Thiès (Sénégal)

    PubMed Central

    Dia, Aliou Amadou; Affangla, Désiré Alain; Dione, Jean-Michel; Akpo, Géraud; Mbengue, Marie; Ka, Mamadou Mourtalla; Diop, Bernard Marcel

    2015-01-01

    Introduction Le pied diabétique se définit comme l'ensemble des manifestations trophiques du pied survenant chez le diabétique par atteinte nerveuse, artérielle et ou infectieuse. Le pied diabétique est un problème majeur de santé publique à l’échelle mondiale avec un taux d'amputation de membres inférieurs très élevé. L’écho-doppler artériel des membres inférieurs est de nos jours incontournable dans la prise en charge du pied diabétique. Le but de cette étude est de montrer la place prépondérante qu'occupe l’écho-doppler artériel dans le bilan lésionnel du pied diabétique. Méthodes Nous avons mené une étude rétrospective monocentrique incluant 46 patients sur une période de 24 mois, de mars 2012 à mars 2014 à l'hôpital Saint-Jean de Dieu, un des deux hôpitaux de référence de la région de Thiès, doté depuis juillet 2011 d'un centre moderne de traitement du diabète et des maladies cardio-métaboliques (Diabcarmet). Dans les critères d'inclusion, nous avons sélectionné tous les patients diabétiques adressés pour un écho-doppler artériel des membres inférieurs dans le cadre d'une prise en charge du pied diabétique. Etaient exclus de l’étude, les patients artéritiques non-diabétiques et les patients diabétiques asymptomatiques référés pour un bilan écho-doppler de routine. Résultats Le sex-ratio était de 1.42 (27 hommes pour 19 femmes). L’âge moyen des patients était de 62,86 ans avec des extrêmes de 23 et 88 ans. 60% des patients (n=28) étaient âgés entre 50 et 70 ans. Le diabète de type 2 était retrouvé chez 95% des patients (n=44) alors que le diabète de type 1 représentait 5% (n=2). La moyenne d’évolution du diabète était estimée à 8 ans, avec des extrêmes de 2 et 20 ans. On notait une atteinte du pied droit chez 24 patients, une atteinte du pied gauche chez 18 patients et une atteinte bilatérale chez 4 patients. La plupart du temps, les lésions du pied diabétique survenaient

  1. The "Umbrella Sign": A Useful Clue in the Diagnosis of Melanocytic Lesions in Sun Damaged Skin.

    PubMed

    Wood, Benjamin A; Harvey, Nathan T

    2016-07-01

    As ultraviolet radiation is an important aetiological agent in melanoma development, the presence of solar elastosis is an important factor in the assessment of any melanocytic lesion. However, melanocytic naevi are also seen in chronically sun damaged skin, particularly in regions with high levels of ultraviolet exposure and fair skinned populations. It has previously been noted that the relationship of a melanocytic proliferation to elastic fibers in the dermis can be of discriminatory value in the separation of melanoma from melanocytic naevus, in particular, it has been proposed that naevi act as a "sunscreen," which may result in a histological clue that the authors colloquially refer to in practice as "the umbrella sign." The aim of this study was to evaluate the patterns of solar elastosis within and beneath melanocytic proliferations developing in sun damaged skin and to determine the utility of the "umbrella sign" in diagnostic practice. We assessed 81 melanocytic proliferations in sun damaged skin for the presence of an umbrella sign, that was present in 49/53 melanocytic naevi (92%) compared with only 2/28 melanomas (7%, P < 0.05). In addition, entrapped elastotic fibers displaying distinct purple discolouration were identified in 16 melanocytic naevi. This finding was not identified in any of the melanomas. The umbrella sign appears to be a useful clue in the distinction of melanoma from melanocytic naevus in sun damaged skin, although as with all histological features in melanocytic pathology, it requires interpretation within a multifactorial assessment cognizant of potential diagnostic pitfalls. PMID:26909586

  2. Altered E-Cadherin Levels and Distribution in Melanocytes Precede Clinical Manifestations of Vitiligo.

    PubMed

    Wagner, Roselyne Y; Luciani, Flavie; Cario-André, Muriel; Rubod, Alain; Petit, Valérie; Benzekri, Laila; Ezzedine, Khaled; Lepreux, Sébastien; Steingrimsson, Eirikur; Taieb, A; Gauthier, Yvon; Larue, Lionel; Delmas, Véronique

    2015-07-01

    Vitiligo is the most common depigmenting disorder resulting from the loss of melanocytes from the basal epidermal layer. The pathogenesis of the disease is likely multifactorial and involves autoimmune causes, as well as oxidative and mechanical stress. It is important to identify early events in vitiligo to clarify pathogenesis, improve diagnosis, and inform therapy. Here, we show that E-cadherin (Ecad), which mediates the adhesion between melanocytes and keratinocytes in the epidermis, is absent from or discontinuously distributed across melanocyte membranes of vitiligo patients long before clinical lesions appear. This abnormality is associated with the detachment of the melanocytes from the basal to the suprabasal layers in the epidermis. Using human epidermal reconstructed skin and mouse models with normal or defective Ecad expression in melanocytes, we demonstrated that Ecad is required for melanocyte adhesiveness to the basal layer under oxidative and mechanical stress, establishing a link between silent/preclinical, cell-autonomous defects in vitiligo melanocytes and known environmental stressors accelerating disease expression. Our results implicate a primary predisposing skin defect affecting melanocyte adhesiveness that, under stress conditions, leads to disappearance of melanocytes and clinical vitiligo. Melanocyte adhesiveness is thus a potential target for therapy aiming at disease stabilization. PMID:25634357

  3. Endothelin-1 increases melanin synthesis in an established sheep skin melanocyte culture.

    PubMed

    Pang, Yamiao; Geng, Jianjun; Qin, Yilong; Wang, Haidong; Fan, Ruiwen; Zhang, Ying; Li, Hongquan; Jiang, Shan; Dong, Changsheng

    2016-08-01

    The aims of the study were to establish a culture system for sheep skin melanocytes and uncover the effects of endothelin-1 on melanin synthesis in cultured melanocytes in order to provide an optimal cell system and a theoretical basis for studying the regulatory mechanism of coat color in sheep. In this study, skin punch biopsies were harvested from the dorsal region of 1-3-yr-old sheep, and skin melanocytes were then obtained by the two-step digestion using dispase II and trypsin/ethylene diamine tetraacetic acid (EDTA). The primary cultures of the melanocytes were established and characterized by dopa-staining, immunocytochemical localization of melanocyte markers, and RT-polymerase chain reaction (PCR) analysis of coat color genes. To determine the effect of endothelin-1 on proliferation and melanin synthesis of melanocytes, the cultured cells were treated with different doses of endothelin-1 (10(-7), 10(-8), 10(-9), 10(-10), and 0 mol/L), and the growth rate of melanocytes, production of melanin, expression of related genes, and location of related protein in cultured cells were examined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), ultraviolet spectrophotometry, qRT-PCR, and immunocytochemical localization, respectively. The results showed that the established melanocyte culture functions properly. Endothelin-1 treatment increased markedly the number of melanocytes and melanin content. In responding to this treatment, expressions of microphthalmia-associated transcription factor (MITF), melanocortin 1 receptor (MC1R), tyrosinase (TYR), and endothelin receptor B (EDNRB) in the melanocytes were significantly up regulated (P < 0.05). Immunocytochemical localization revealed that TYR was mainly localized in the cytoplasm. Positive staining of TYR in the melanocytes was significant. The findings demonstrated that the culture system of sheep skin melanocytes was established successfully in vitro, and endothelin-1 promotes the

  4. Mitochondria are more numerous and smaller in pink-eyed dilution melanoblasts and melanocytes than in wild-type melanocytes in the neonatal mouse epidermis.

    PubMed

    Hirobe, Tomohisa; Ishizuka, Kenji; Ogawa, Shigeru; Abe, Hiroyuki

    2008-11-01

    Abstract The mouse pink-eyed dilution (p) locus is known to control the melanin content in melanocytes. However, it was not known whether the p gene is involved in regulating the proliferation and differentation of melanocytes during development, especially the biogenesis of melanosomes and other organelles. Epidermal cell suspensions of neonatal dorsal skin derived from mice wild type for the p locus (black, C57BL/10JHir-P/P) and their congenic mutant phenotype (pink-eyed dilution, C57BL/10JHir-p/p) were cultured in serum-free melanocyte-proliferation medium (MDMD). The supplement of additional L-tyrosine (Tyr) into the MDMD stimulated the differentiation of p/p melanoblasts into melanocytes. Electron microscopy revealed that in p/p melanoblasts and melanocytes treated with L-Tyr, the number of stage II and III melanosomes dramatically increased. Moreover, p/p melanoblasts possessed smaller but more numerous mitochondria than P/P melanocytes. The treatment of p/p melanoblasts and melanocytes with L-Tyr decreased the number of mitochondria. The supplement of 2, 4-dinitrophenol (DNP), an inhibitor of mitochondrial function, into the MDMD stimulated both the proliferation and differentiation of p/p melanoblasts. Simultaneous treatment of DNP and L-Tyr dramatically stimulated the differetiation of p/p melanocytes. These results suggest that L-Tyr and some unknown factors related to mitochondrial function may influence the differentiation of melanoblasts in the epidermis of p/p mice. PMID:19267617

  5. Diagnostic clinique et paraclinique des infections ostéoarticulaires digitales dans les brûlures thermiques de la main

    PubMed Central

    Zaoui, A.; Mahdhi, N.; Ben Maitigue, M.; Maaref, K.; Jemni, S.; Bouaziz, M.A.; Regaieg, H.; Dakkem, M.; Zine El Abidine, M.; Ben Fredj, M.; Khachnaoui, F.; Rejeb, N.

    2013-01-01

    Summary Les infections ostéo-articulaires digitales de la main brûlée sont particulières car longtemps méconnu. Leur diagnostic n’a pratiquement jamais été abordé dans la littérature. On distingue d’une part les ostéoarthrites survenant à la phase aiguë de la brûlure chez le patient grand brûlé, sédaté où le diagnostic est difficile en réanimation car la clinique n’est pas parlante et d’autre part les ostéoarthrites découvertes à la phase de rééducation, où douleur, tuméfaction, raideur et signes radiologiques sont nets. Le diagnostic de ces infections doit être précoce à fin de préserver la fonction de la main. PMID:24133401

  6. Aspects cliniques et biologiques des anémies pédiatriques dans un hôpital de District urbain au Cameroun

    PubMed Central

    Koum, Danièle Kedy; Tsakeu, Eveline Ngouadjeu Dongho; Sack, Françoise Ngo; Ngalagou, Pierre Tchienrg Moueleu; Kamanyi, Albert; Mandengue, Samuel Honoré

    2013-01-01

    Introduction L'anémie est un problème de santé publique prédominant chez les enfants et les femmes en âge de procréer. L'objectif de cette étude était de caractériser et de déterminer sa prévalence chez les enfants âgés de 6 mois à 14 ans hospitalisés à l'hôpital de District de Bonassama à Douala-Cameroun. Méthodes Il s'agissait d'une étude descriptive transversale qui s'est déroulée de février à mars 2012 avec une collecte rétrospective des données de janvier 2009 à mars 2012. Etaient inclus, les patients de 6 mois à 14 ans hospitalisés, quel que soit leur motif de consultation et leur diagnostic, et ayant réalisé au moins une numération formule sanguine (NFS). Les patients transfusés moins de 120 jours avant la NFS étaient exclus. L’âge, le sexe, les motifs de consultation, les signes cliniques, les diagnostics et les résultats de la NFS étaient enregistrés. L'anémie était définie selon les critères de l'OMS. La recherche étiologique était guidée par les signes cliniques et les examens complémentaires. Résultats La prévalence de l'anémie était de 88,5%. Le sex-ratio garçon/fille était de 1,3. La fièvre était le premier motif de consultation. L'anémie modérée prédominait (62,7%). Le taux moyen d'hémoglobine chez les patients anémiques était de 8,6 ± 1,7 g/dl (2,3- 11,4). L'anémie microcytaire hypochrome dominait (48,5%). Le paludisme était la principale pathologie (46,3%). Le taux de mortalité des patients anémiques était de 5,9%. Conclusion La prévalence de l'anémie était élevée avec une prédominance des formes hypochromes microcytaires. La principale étiologie était le paludisme. PMID:24772220

  7. Asymmetry and irregularity border as discrimination factor between melanocytic lesions

    NASA Astrophysics Data System (ADS)

    Sbrissa, David; Pratavieira, Sebastião.; Salvio, Ana Gabriela; Kurachi, Cristina; Bagnato, Vanderlei Salvadori; Costa, Luciano Da Fontoura; Travieso, Gonzalo

    2015-06-01

    Image processing tools have been widely used in systems supporting medical diagnosis. The use of mobile devices for the diagnosis of melanoma can assist doctors and improve their diagnosis of a melanocytic lesion. This study proposes a method of image analysis for melanoma discrimination from other types of melanocytic lesions, such as regular and atypical nevi. The process is based on extracting features related with asymmetry and border irregularity. It were collected 104 images, from medical database of two years. The images were obtained with standard digital cameras without lighting and scale control. Metrics relating to the characteristics of shape, asymmetry and curvature of the contour were extracted from segmented images. Linear Discriminant Analysis was performed for dimensionality reduction and data visualization. Segmentation results showed good efficiency in the process, with approximately 88:5% accuracy. Validation results presents sensibility and specificity 85% and 70% for melanoma detection, respectively.

  8. Spontaneous Involution of Congenital Melanocytic Nevus With Halo Phenomenon

    PubMed Central

    Lee, Noo Ri; Chung, Hee-Chul; Hong, Hannah; Lee, Jin Wook

    2015-01-01

    Abstract: Congenital melanocytic nevus (CMN) is a neural crest-derived hamartoma, which appear at or soon after birth. CMN has a dynamic course and may show variable changes over time, including spontaneous involution. Spontaneous involution of CMN is a rare phenomenon and is often reported in association with halo phenomenon or vitiligo. The mechanism of halo phenomenon is yet to be investigated but is suggested to be a destruction of melanocytes by immune responses of cytotoxic T cells or IgM autoantibodies. Here, the authors report an interesting case of spontaneously regressed medium-sized CMN with halo phenomenon and without vitiligo, which provides evidence that cytotoxic T cells account for the halo formation and pigmentary regression of CMN. PMID:26588343

  9. Ultraviolet radiation directly induces pigment production by cultured human melanocytes

    SciTech Connect

    Friedmann, P.S.; Gilchrest, B.A.

    1987-10-01

    In humans the major stimulus for cutaneous pigmentation is ultraviolet radiation (UVR). Little is known about the mechanism underlying this response, in part because of the complexity of interactions in whole epidermis. Using a recently developed culture system, human melanocytes were exposed daily to a physiologic range of UVR doses from a solar simulator. Responses were determined 24 hours after the last exposure. There was a dose-related increase in melanin content per cell and uptake of /sup 14/C-DOPA, accompanied by growth inhibition. Cells from donors of different racial origin gave proportionately similar increases in melanin, although there were approximately tenfold differences in basal values. Light and electron microscopy revealed UVR-stimulated increases in dendricity as well as melanosome number and degree of melanization, analogous to the well-recognized melanocyte changes following sun exposure of intact skin. Similar responses were seen with Cloudman S91 melanoma cells, although this murine cell line required lower UVR dosages and fewer exposures for maximal stimulation. These data establish that UVR is capable of directly stimulating melanogenesis. Because cyclic AMP elevation has been associated in some settings with increased pigment production by cultured melanocytes, preliminary experiments were conducted to see if the effects of UVR were mediated by cAMP. Both alpha-MSH and isobutylmethylxanthine (IBMX), as positive controls, caused a fourfold increase in cAMP level in human melanocytes and/or S91 cells, but following a dose of UVR sufficient to stimulate pigment production there was no change in cAMP level up to 4 hours after exposure. Thus, it appears that the UVR-induced melanogenesis is mediated by cAMP-independent mechanisms.

  10. Epidermal nevi with aberrant epidermal structure in keratinocytes and melanocytes.

    PubMed

    Oiso, Naoki; Sugawara, Koji; Yonamine, Ayano; Tsuruta, Daisuke; Kawada, Akira

    2015-04-01

    Epidermal nevi are congenital cutaneous hamartomas caused by embryonic somatic mutations. Ultrastructural features of adult epidermal nevi have rarely been investigated. Herein, we report a case involving a Japanese adult who had epidermal nevi with right congenital blindness and a right accessory nipple. The histopathologic and ultrastructural studies showed divergent abnormal epidermal structures in both melanocytes and keratinocytes. Our case indicates the need to further investigate histopathologic, ultrastructural, and genetic associations in adult epidermal nevi. PMID:25657059

  11. Cellular origin and developmental mechanisms during the formation of skin melanocytes

    SciTech Connect

    Ernfors, Patrik

    2010-05-01

    Melanocytes are derived from the neural crest (NC), which are transient multipotent cells arising by delamination from the developing dorsal neural tube. During recent years, signaling systems and molecular mechanisms of melanocyte development have been studied in detail, but the exact diversification of the NC into melanocytes and how they migrate, expand and disperse in the skin have not been fully understood. The recent finding that Schwann cell precursors (SCPs) of the growing nerve represents a stem cell niche from which various cell types, including Schwann cells, endoneural fibroblasts and melanocytes arise has exposed new knowledge on the cellular basis for melanocyte development. This opens for the identification of new factors and reinterpretation of old data on cell fate instructive, proliferative, survival and cell homing factors participating in melanocyte development.

  12. Diagnostic utility of 5-hydroxymethylcytosine immunohistochemistry in melanocytic proliferations

    PubMed Central

    Rodić, Nemanja; Zampella, John; Sharma, Reema; Burns, Kathleen H.; Taube, Janis M.

    2015-01-01

    Decreased hydroxymethylated cytosine (5-hydroxymethycytosine, 5-hmC) is reported to correlate with melanocyte dysplasia. The purpose of this study was to assess the diagnostic utility of this observation. 5-hmC immunohistochemistry was performed on tissue microarrays containing 171-melanocytic lesions from two different institutions. An immunohistochemical staining score representing the percentage and intensity of nuclear staining was assigned. The performance characteristics of 5-hmC immunohistochemistry for discriminating between a nevus and melanoma were determined. Additional cases of melanoma arising in a nevus (n = 8), nodal nevi (n = 5) and melanoma micrometastases to a lymph node (n = 6) were also assessed. Pronounced 5-hmC loss was observed in melanomas when compared with nevi (mean ± standard deviation = 6.71 ± 11.78 and 55.19 ± 23.66, respectively, p < 0.0001). While the mean immunohistochemical staining score values for melanocytic nevi and melanoma were distinct, there was considerable variability in immunohistochemical staining score within a single diagnostic category. The sensitivity and specificity of this assay for nevus vs. melanoma is 92.74 and 97.78%, respectively. Distinct biphasic staining patterns were observed in cases of melanoma arising in association with a nevus. Relative changes of 5-hmC expression within a single lesion may be more informative than absolute values when using 5-hmC as a diagnostic adjunct. PMID:26239102

  13. UVA Phototransduction Drives Early Melanin Synthesis in Human Melanocytes

    PubMed Central

    Wicks, Nadine L.; Chan, Jason W.; Najera, Julia A.; Ciriello, Jonathan M.; Oancea, Elena

    2013-01-01

    Summary Exposure of human skin to solar ultraviolet radiation (UVR), a powerful carcinogen [1] comprising ~95% UVA and ~5% UVB at the Earth’s surface, promotes melanin synthesis in epidermal melanocytes [2, 3], which protects skin from DNA damage [4, 5]. UVB causes DNA lesions [6] that lead to transcriptional activation of melanin-producing enzymes, resulting in delayed skin pigmentation within days [7]. In contrast, UVA causes primarily oxidative damage [8] and leads to immediate pigment darkening (IPD) within minutes, via an unknown mechanism [9, 10]. No receptor protein directly mediating phototransduction in skin has been identified. Here we demonstrate that exposure of primary human epidermal melanocytes (HEMs) to UVA causes calcium mobilization and early melanin synthesis. Calcium responses were abolished by treatment with G protein or PLC inhibitors, or by depletion of intracellular calcium stores. We show that the visual photopigment rhodopsin [11] is expressed in HEMs and contributes to UVR phototransduction. Upon UVR exposure, significant melanin production was measured within one hour; cellular melanin continued to increase in a retinal- and calcium-dependent manner up to five-fold after 24 hours. Our findings identify a novel UVA-sensitive signaling pathway in melanocytes that leads to calcium mobilization and melanin synthesis, and may underlie the mechanism of IPD in human skin. PMID:22055294

  14. Automatic Classification of Specific Melanocytic Lesions Using Artificial Intelligence

    PubMed Central

    Jaworek-Korjakowska, Joanna; Kłeczek, Paweł

    2016-01-01

    Background. Given its propensity to metastasize, and lack of effective therapies for most patients with advanced disease, early detection of melanoma is a clinical imperative. Different computer-aided diagnosis (CAD) systems have been proposed to increase the specificity and sensitivity of melanoma detection. Although such computer programs are developed for different diagnostic algorithms, to the best of our knowledge, a system to classify different melanocytic lesions has not been proposed yet. Method. In this research we present a new approach to the classification of melanocytic lesions. This work is focused not only on categorization of skin lesions as benign or malignant but also on specifying the exact type of a skin lesion including melanoma, Clark nevus, Spitz/Reed nevus, and blue nevus. The proposed automatic algorithm contains the following steps: image enhancement, lesion segmentation, feature extraction, and selection as well as classification. Results. The algorithm has been tested on 300 dermoscopic images and achieved accuracy of 92% indicating that the proposed approach classified most of the melanocytic lesions correctly. Conclusions. A proposed system can not only help to precisely diagnose the type of the skin mole but also decrease the amount of biopsies and reduce the morbidity related to skin lesion excision. PMID:26885520

  15. EFFECT OF PARACETAMOL ON MELANIZATION PROCESS IN HUMAN EPIDERMAL MELANOCYTES.

    PubMed

    Wrześniok, Dorota; Oprzondek, Martyna; Hechmann, Anna; Beberok, Artur; Otreba, Michał; Buszman, Ewa

    2016-01-01

    Paracetamol (acetaminophen) is commonly used as a drug of choice for treatment of pain and fever. Unlike non-steroidal anti-inflammatory drugs (NSAIDs) it does not cause gastrointestinal damage or untoward cardiorenal effects, however cutaneous adverse effects have been reported. It is known that paracetamol binds to melanin biopolymers, but the relation between the affinity of this drug to melanin and its toxicity is not documented. The aim of this work was to examine the impact of paracetamol on melanogenesis in cultured human normal epidermal melanocytes (HEMn-DP). The effect of paracetamol on cell viability was determined by WST-1 assay, melanin content and tyrosinase activity were measured spectrophotometrically. It has been demonstrated that paracetamol induced concentration-dependent loss in melanocytes viability. The value of EC50 was found to be - 20.0 mM. The analyzed drug inhibited melanin biosynthesis in a concentration-dependent manner by decreasing the melanin content as well as the tyrosinase activity. The demonstrated inhibitory effect of paracetamol on melanization process in normal epidermal melanocytes in vitro may explain the potential role of melanin biopolymer in the mechanisms of undesirable side effects of this drug in vivo, as a result of its accumulation in pigmented tissues. PMID:27476283

  16. UVB induces atypical melanocytic lesions and melanoma in human skin.

    PubMed Central

    Atillasoy, E. S.; Seykora, J. T.; Soballe, P. W.; Elenitsas, R.; Nesbit, M.; Elder, D. E.; Montone, K. T.; Sauter, E.; Herlyn, M.

    1998-01-01

    A direct causal relationship between ultraviolet (UV) light in the B range and melanoma development has not been demonstrated in humans; this study aims to establish causality. A total of 158 RAG-1 mice, grafted with human newborn foreskin, were separated into four groups and observed for a median of 10 months: 1) no treatment, 2) a single treatment with 7,12-dimethyl(a)benzanthracene (DMBA), 3) UVB irradiation at 500 J/m2 alone, three times weekly, and 4) a combination of DMBA and UVB. Twenty-three percent of 40 normal human skin grafts treated with UVB only and 38% of 48 grafts treated with the combination of DMBA and UVB developed solar lentigines within 5 to 10 months of treatment. Melanocytic hyperplasia was found in 73% of all UVB-treated xenografts. Histological melanocytic changes resembling lentigo and lentigo maligna were seen in several skin grafts treated with both DMBA and UVB. In one graft of an animal treated with a combination of DMBA and UVB, a human malignant melanoma, nodular type, developed. This experimental system demonstrates that chronic UVB irradiation with or without an initiating carcinogen can induce human melanocytic lesions, including melanoma. Images Figure 2 Figure 3 Figure 4 Figure 5 PMID:9588887

  17. Differential PAX3 functions in normal skin melanocytes and melanoma cells

    SciTech Connect

    Medic, Sandra; Rizos, Helen; Ziman, Mel

    2011-08-12

    Highlights: {yields} PAX3 retains embryonic roles in adult melanocytes and melanoma cells. {yields} Promotes 'stem' cell-like phenotype via NES and SOX9 in both cells types. {yields} Regulates melanoma and melanocyte migration through MCAM and CSPG4. {yields} PAX3 regulates melanoma but not melanocyte proliferation via TPD52. {yields} Regulates melanoma cell (but not melanocyte) survival via BCL2L1 and PTEN. -- Abstract: The PAX3 transcription factor is the key regulator of melanocyte development during embryogenesis and is also frequently found in melanoma cells. While PAX3 is known to regulate melanocyte differentiation, survival, proliferation and migration during development, it is not clear if its function is maintained in adult melanocytes and melanoma cells. To clarify this we have assessed which genes are targeted by PAX3 in these cells. We show here that similar to its roles in development, PAX3 regulates complex differentiation networks in both melanoma cells and melanocytes, in order to maintain cells as 'stem' cell-like (via NES and SOX9). We show also that mediators of migration (MCAM and CSPG4) are common to both cell types but more so in melanoma cells. By contrast, PAX3-mediated regulation of melanoma cell proliferation (through TPD52) and survival (via BCL2L1 and PTEN) differs from that in melanocytes. These results suggest that by controlling cell proliferation, survival and migration as well as maintaining a less differentiated 'stem' cell like phenotype, PAX3 may contribute to melanoma development and progression.

  18. Melanocytes in the Skin – Comparative Whole Transcriptome Analysis of Main Skin Cell Types

    PubMed Central

    Reemann, Paula; Reimann, Ene; Ilmjärv, Sten; Porosaar, Orm; Silm, Helgi; Jaks, Viljar; Vasar, Eero; Kingo, Külli; Kõks, Sulev

    2014-01-01

    Melanocytes possess several functions besides a role in pigment synthesis, but detailed characteristics of the cells are still unclear. We used whole transcriptome sequencing (RNA-Seq) to assess differential gene expression of cultivated normal human melanocytes with respect to keratinocytes, fibroblasts and whole skin. The present results reveal cultivated melanocytes as highly proliferative cells with possible stem cell-like properties. The enhanced readiness to regenerate makes melanocytes the most vulnerable cells in the skin and explains their high risk of developing into malignant melanoma. PMID:25545474

  19. The trk family of receptors mediates nerve growth factor and neurotrophin-3 effects in melanocytes.

    PubMed Central

    Yaar, M; Eller, M S; DiBenedetto, P; Reenstra, W R; Zhai, S; McQuaid, T; Archambault, M; Gilchrest, B A

    1994-01-01

    We have recently shown that (a) human melanocytes express the p75 nerve growth factor (NGF) receptor in vitro; (b) that melanocyte dendricity and migration, among other behaviors, are regulated at least in part by NGF; and (c) that cultured human epidermal keratinocytes produce NGF. We now report that melanocyte stimulation with phorbol 12-tetra decanoate 13-acetate (TPA), previously reported to induce p75 NGF receptor, also induces trk in melanocytes, and TPA effect is further potentiated by the presence of keratinocytes in culture. Moreover, trk in melanocytes becomes phosphorylated within minutes after NGF stimulation. As well, cultures of dermal fibroblasts express neurotrophin-3 (NT-3) mRNA; NT-3 mRNA levels in cultured fibroblasts are modulated by mitogenic stimulation, UV irradiation, and exposure to melanocyte-conditioned medium. Moreover, melanocytes constitutively express low levels of trk-C, and its expression is downregulated after TPA stimulation. NT-3 supplementation to cultured melanocytes maintained in Medium 199 alone prevents cell death. These combined data suggest that melanocyte behavior in human skin may be influenced by neurotrophic factors, possibly of keratinocyte and fibroblast origin, which act through high affinity receptors. Images PMID:7929831

  20. Ultraviolet B, melanin and mitochondrial DNA: Photo-damage in human epidermal keratinocytes and melanocytes modulated by alpha-melanocyte-stimulating hormone

    PubMed Central

    Böhm, Markus; Hill, Helene Z.

    2016-01-01

    Alpha-melanocyte-stimulating hormone (alpha-MSH) increases melanogenesis and protects from UV-induced DNA damage. However, its effect on mitochondrial DNA (mtDNA) damage is unknown. We have addressed this issue in a pilot study using human epidermal keratinocytes and melanocytes incubated with alpha-MSH and irradiated with UVB. Real-time touchdown PCR was used to quantify total and deleted mtDNA. The deletion detected encompassed the common deletion but was more sensitive to detection. There were 4.4 times more mtDNA copies in keratinocytes than in melanocytes. Irradiation alone did not affect copy numbers. Alpha-MSH slightly increased copy numbers in both cell types in the absence of UVB and caused a similar small decrease in copy number with dose in both cell types. Deleted copies were nearly twice as frequent in keratinocytes as in melanocytes. Alpha-MSH reduced the frequency of deleted copies by half in keratinocytes but not in melanocytes. UVB dose dependently led to an increase in the deleted copy number in alpha-MSH-treated melanocytes. UVB irradiation had little effect on deleted copy number in alpha-MSH-treated keratinocytes. In summary, alpha-MSH enhances mtDNA damage in melanocytes presumably by increased melanogenesis, while α-MSH is protective in keratinocytes, the more so in the absence of irradiation. PMID:27303631

  1. New melanogenesis and photobiological processes in activation and proliferation of precursor melanocytes after UV-exposure: ultrastructural differentiation of precursor melanocytes from Langerhans cells

    SciTech Connect

    Jimbow, K.; Uesugi, T.

    1982-02-01

    Photobiological processes involving new melanogenesis after exposure to ultraviolet (UV) light were experimentally studied in C57 black adult mice by histochemistry, cytochemistry, and autoradiography. The trunk and the plantar region of the foot, where no functioning melanocytes were present before exposure, were exposed to UV-A for 14 consecutive days. Both regions revealed a basically similar pattern for new melanogenesis which involved an activation of precursor melanocytes. Essentially all of ''indeterminate'' cells appeared to be precursor melanocytes, the fine structure of which could be differentiated even from poorly developed Langerhans cells. New melanogenesis was manifested by 4 stages of cellular and subcellular reactions of these cells as indicated by histochemistry of dihydroxyphenylalanine (dopa) and autoradiography of thymidine incorporation: (a) an initial lag in the activation of precursor melanocytes with development of Golgi cisternae and rough endoplasmic reticulum followed by formation of unmelanized melanosomes (day 0 to 2); (b) synthesis of active tyrosinase accumulated in Golgi cisternae and vesicles with subsequent formation of melanized melanosomes in these cells (day 3 to 5); (c) mitotic proliferation of many of these activated cells, followed by an exponential increase of new melanocytes (day 6 to 7); and (d) melanosome transfer with differentiation of 10 nm filaments and arborization of dendrites, but without any significant change in the melanocyte population (day 8 to 14). The melanosome transfer was, however, not obvious until after 7 days of exposure. The size of newly synthesized melanosomes was similar to that of tail skin where native melanocytes were present before exposure.

  2. Ultraviolet B, melanin and mitochondrial DNA: Photo-damage in human epidermal keratinocytes and melanocytes modulated by alpha-melanocyte-stimulating hormone.

    PubMed

    Böhm, Markus; Hill, Helene Z

    2016-01-01

    Alpha-melanocyte-stimulating hormone (alpha-MSH) increases melanogenesis and protects from UV-induced DNA damage. However, its effect on mitochondrial DNA (mtDNA) damage is unknown. We have addressed this issue in a pilot study using human epidermal keratinocytes and melanocytes incubated with alpha-MSH and irradiated with UVB. Real-time touchdown PCR was used to quantify total and deleted mtDNA. The deletion detected encompassed the common deletion but was more sensitive to detection. There were 4.4 times more mtDNA copies in keratinocytes than in melanocytes. Irradiation alone did not affect copy numbers. Alpha-MSH slightly increased copy numbers in both cell types in the absence of UVB and caused a similar small decrease in copy number with dose in both cell types. Deleted copies were nearly twice as frequent in keratinocytes as in melanocytes. Alpha-MSH reduced the frequency of deleted copies by half in keratinocytes but not in melanocytes. UVB dose dependently led to an increase in the deleted copy number in alpha-MSH-treated melanocytes. UVB irradiation had little effect on deleted copy number in alpha-MSH-treated keratinocytes. In summary, alpha-MSH enhances mtDNA damage in melanocytes presumably by increased melanogenesis, while α-MSH is protective in keratinocytes, the more so in the absence of irradiation. PMID:27303631

  3. Profil epidemiologique des brulures d'enfants admis au Centre National des Brules, Maroc

    PubMed Central

    Zahid, A.; Atannaz, J.; Alaoui, M.; Rafik, A.; Ezzoubi, M.; Diouri, M.; Chlihi, A.; Bahechar, N.; Boukind, E.H.

    2011-01-01

    Summary Ce travail rétrospectif analyse les particularités épidémiologiques de 543 cas de brûlures d'enfants, représentant 45,7% des admissions de notre centre, en vue de déterminer les éléments pouvant contribuer à renforcer la prévention, qui reste le traitement de choix de cette pathologie. La moyenne d'âge est de 4,25 ans avec une prédilection pour la tranche d'âge d'un à cinq ans, avec 42,5% des cas. Une atteinte masculine est retrouvée dans 63,5% des cas. La brûlure survient à domicile dans 85,1% et accidentellement dans 95% des cas. Les brûlures thermiques représentent 96,5% des causes dominées par les liquides dans 69,3% des cas. La surface cutanée brûlée est ≥ 20% dans 52,3%. La brûlure intéresse essentiellement les membres supérieurs (79,1%). 56,8% des enfants sont transférés par d'autres hôpitaux et le délai de prise en charge hospitalière est supérieur à 6 heures dans 65,5%. Le taux de mortalité a été de 13,2%. PMID:22639559

  4. Narrow Band Ultraviolet B Treatment for Human Vitiligo Is Associated with Proliferation, Migration, and Differentiation of Melanocyte Precursors.

    PubMed

    Goldstein, Nathaniel B; Koster, Maranke I; Hoaglin, Laura G; Spoelstra, Nicole S; Kechris, Katerina J; Robinson, Steven E; Robinson, William A; Roop, Dennis R; Norris, David A; Birlea, Stanca A

    2015-08-01

    In vitiligo, the autoimmune destruction of epidermal melanocytes produces white spots that can be repigmented by melanocyte precursors from the hair follicles, following stimulation with UV light. We examined by immunofluorescence the distribution of melanocyte markers (C-KIT, DCT, PAX3, and TYR) coupled with markers of proliferation (KI-67) and migration (MCAM) in precursors and mature melanocytes from the hair follicle and the epidermis of untreated and narrow band UVB (NBUVB)-treated human vitiligo skin. NBUVB was associated with a significant increase in the number of melanocytes in the infundibulum and with restoration of the normal melanocyte population in the epidermis, which was lacking in the untreated vitiligo. We identified several precursor populations (melanocyte stem cells, melanoblasts, and other immature phenotypes), and progressively differentiating melanocytes, some with putative migratory and/or proliferative abilities. The primary melanocyte germ was present in the untreated and treated hair follicle bulge, whereas a possible secondary melanocyte germ composed of C-KIT+ melanocytes was found in the infundibulum and interfollicular epidermis of UV-treated vitiligo. This is an exceptional model for studying the mobilization of melanocyte stem cells in human skin. Improved understanding of this process is essential for designing better treatments for vitiligo, ultimately based on melanocyte stem cell activation and mobilization. PMID:25822579

  5. Narrow Band Ultraviolet B Treatment for Human Vitiligo Is Associated with Proliferation, Migration, and Differentiation of Melanocyte Precursors

    PubMed Central

    Goldstein, Nathaniel B.; Koster, Maranke I.; Hoaglin, Laura G.; Spoelstra, Nicole S.; Kechris, Katerina J.; Robinson, Steven E.; Robinson, William A.; Roop, Dennis R.; Norris, David A.; Birlea, Stanca A.

    2015-01-01

    In vitiligo, the autoimmune destruction of epidermal melanocytes produces white spots that can be repigmented by melanocyte precursors from the hair follicles, following stimulation with UV light. We examined by immunofluorescence the distribution of melanocyte markers (C-KIT, DCT, PAX3, and TYR) coupled with markers of proliferation (KI-67) and migration (MCAM) in precursors and mature melanocytes from the hair follicle and the epidermis of untreated and narrow band UVB (NBUVB)-treated human vitiligo skin. NBUVB was associated with a significant increase in the number of melanocytes in the infundibulum and with restoration of the normal melanocyte population in the epidermis, which was lacking in the untreated vitiligo. We identified several precursor populations (melanocyte stem cells, melanoblasts, and other immature phenotypes), and progressively differentiating melanocytes, some with putative migratory and/or proliferative abilities. The primary melanocyte germ was present in the untreated and treated hair follicle bulge, whereas a possible secondary melanocyte germ composed of C-KIT+ melanocytes was found in the infundibulum and interfollicular epidermis of UV-treated vitiligo. This is an exceptional model for studying the mobilization of melanocyte stem cells in human skin. Improved understanding of this process is essential for designing better treatments for vitiligo, ultimately based on melanocyte stem cell activation and mobilization. PMID:25822579

  6. Propriétés électroniques et schémas de bandes dans les semi-conducteurs amorphes. II. Etude des phénomènes de transport

    NASA Astrophysics Data System (ADS)

    Moliton, André; Ratier, Bernard

    We present the particular study of three important electric parameters which characterize an amorphous semiconductor. The band scheme is the Mott - Davis model and the three parameters : dark conductivity, thermoelectric power and alternative conductivity are determined versus temperature : calculations are presented on the more general manner for the successive energy levels (extended states, localized states in band tails, localized states near Fermi level). The schematic representations are finally proposed : at the classical curves obtained for the conductivities, we add a peculiar scheme for the thermoelectric power : its study is of importance for determining (with its sign) the type of amorphous semiconductor. Nous présentons de façon détaillée l'étude théorique de trois importants paramètres électriques susceptibles de caractériser un semi-conducteur amorphe. Le schéma de bande retenu est celui de Mott - Davis et les trois paramètres : conductivité continue, pouvoir thermoélectrique et conductivité alternative sont déterminés en particulier en fonction de la température : nous nous sommes attachés à présenter les calculs sous leur forme la plus générale possible en faisant intervenir successivement les différents mécanismes relatifs aux différents niveaux d'énergie (énergie relative aux états délocalisés, localisés dans les queues de bande, localisés au voisinage du niveau de Fermi). Les représentations schématiques, classiques pour la conductivité continue et à un degré moindre pour la conductivité alternative, sont proposées : nous détaillons en particulier celle du pouvoir thermoélectrique S dont l'étude est en fait essentielle car le signe de S (cf. Mott) est une des seules caractérisations fiables du type de semi-conducteur amorphe étudié.

  7. Chromatin-Remodelling Complex NURF Is Essential for Differentiation of Adult Melanocyte Stem Cells.

    PubMed

    Koludrovic, Dana; Laurette, Patrick; Strub, Thomas; Keime, Céline; Le Coz, Madeleine; Coassolo, Sebastien; Mengus, Gabrielle; Larue, Lionel; Davidson, Irwin

    2015-10-01

    MIcrophthalmia-associated Transcription Factor (MITF) regulates melanocyte and melanoma physiology. We show that MITF associates the NURF chromatin-remodelling factor in melanoma cells. ShRNA-mediated silencing of the NURF subunit BPTF revealed its essential role in several melanoma cell lines and in untransformed melanocytes in vitro. Comparative RNA-seq shows that MITF and BPTF co-regulate overlapping gene expression programs in cell lines in vitro. Somatic and specific inactivation of Bptf in developing murine melanoblasts in vivo shows that Bptf regulates their proliferation, migration and morphology. Once born, Bptf-mutant mice display premature greying where the second post-natal coat is white. This second coat is normally pigmented by differentiated melanocytes derived from the adult melanocyte stem cell (MSC) population that is stimulated to proliferate and differentiate at anagen. An MSC population is established and maintained throughout the life of the Bptf-mutant mice, but these MSCs are abnormal and at anagen, give rise to reduced numbers of transient amplifying cells (TACs) that do not express melanocyte markers and fail to differentiate into mature melanin producing melanocytes. MSCs display a transcriptionally repressed chromatin state and Bptf is essential for reactivation of the melanocyte gene expression program at anagen, the subsequent normal proliferation of TACs and their differentiation into mature melanocytes. PMID:26440048

  8. Chromatin-Remodelling Complex NURF Is Essential for Differentiation of Adult Melanocyte Stem Cells

    PubMed Central

    Koludrovic, Dana; Laurette, Patrick; Strub, Thomas; Keime, Céline; Le Coz, Madeleine; Coassolo, Sebastien; Mengus, Gabrielle; Larue, Lionel; Davidson, Irwin

    2015-01-01

    MIcrophthalmia-associated Transcription Factor (MITF) regulates melanocyte and melanoma physiology. We show that MITF associates the NURF chromatin-remodelling factor in melanoma cells. ShRNA-mediated silencing of the NURF subunit BPTF revealed its essential role in several melanoma cell lines and in untransformed melanocytes in vitro. Comparative RNA-seq shows that MITF and BPTF co-regulate overlapping gene expression programs in cell lines in vitro. Somatic and specific inactivation of Bptf in developing murine melanoblasts in vivo shows that Bptf regulates their proliferation, migration and morphology. Once born, Bptf-mutant mice display premature greying where the second post-natal coat is white. This second coat is normally pigmented by differentiated melanocytes derived from the adult melanocyte stem cell (MSC) population that is stimulated to proliferate and differentiate at anagen. An MSC population is established and maintained throughout the life of the Bptf-mutant mice, but these MSCs are abnormal and at anagen, give rise to reduced numbers of transient amplifying cells (TACs) that do not express melanocyte markers and fail to differentiate into mature melanin producing melanocytes. MSCs display a transcriptionally repressed chromatin state and Bptf is essential for reactivation of the melanocyte gene expression program at anagen, the subsequent normal proliferation of TACs and their differentiation into mature melanocytes. PMID:26440048

  9. Ocular findings in a case of periorbital giant congenital melanocytic nevus

    PubMed Central

    Raina, Usha K.; Seth, Anisha; Gupta, Anika; Batta, Supriya

    2014-01-01

    Giant congenital melanocytic nevus (GCMN) is a large melanocytic nevus that rarely occurs in the periorbital region. Various systemic, as well as ophthalmic associations, have been reported with GCMN. However, there is only one case report describing ophthalmic findings in periorbital GCMN. We describe the ocular findings in a case of periorbital GCMN. PMID:25378884

  10. Size Functions for the Morphological Analysis of Melanocytic Lesions

    PubMed Central

    Ferri, Massimo; Stanganelli, Ignazio

    2010-01-01

    Size Functions and Support Vector Machines are used to implement a new automatic classifier of melanocytic lesions. This is mainly based on a qualitative assessment of asymmetry, performed by halving images by several lines through the center of mass, and comparing the two halves in terms of color, mass distribution, and boundary. The program is used, at clinical level, with two thresholds, so that comparison of the two outputs produces a report of low-middle-high risk. Experimental results on 977 images, with cross-validation, are reported. PMID:20300598

  11. Bilateral diffuse uveal melanocytic proliferation: a management dilemma

    PubMed Central

    Alrashidi, Salah; Aziz, Ayman A; Krema, Hatem

    2014-01-01

    A female patient suffered from gradual decline of vision for few months. She presented with bilateral multiple pigmented choroidal tumours, associated with overlying retinal changes. The clinical presentation suggested bilateral diffuse uveal melanocytic proliferation (BDUMP) syndrome, which is a paraneoplastic disease, although there was no evidence of any concurrent malignancy. The periodic systemic surveillance that was undertaken for the following 4 years failed to reveal any occult cancer. Nevertheless, there has been relentless progressive deterioration in vision as a consequence of BDUMP syndrome. The management of the declining vision in BDUMP syndrome is challenging and controversial. PMID:24855079

  12. The most common mistakes on dermatoscopy of melanocytic lesions

    PubMed Central

    Kamińska-Winciorek, Grażyna

    2015-01-01

    Dermatoscopy is a method of in vivo evaluation of the structures within the epidermis and dermis. Currently, it may be the most precise pre-surgical method of diagnosing melanocytic lesions. Diagnostic errors may result in unnecessary removal of benign lesions or what is even worse, they can cause early and very early melanomas to be overlooked. Errors in assessment of dermatoscopy can be divided into those arising from failure to maintain proper test procedures (procedural and technical errors) and knowledge based mistakes related to the lack of sufficient familiarity and experience in dermatoscopy. The article discusses the most common mistakes made by beginner or inexperienced dermatoscopists. PMID:25821425

  13. Blocage de Coulomb dans une boite quantique laterale contenant un faible nombre d'electrons

    NASA Astrophysics Data System (ADS)

    Gould, Charles

    Dans ce travail on utilise une nouvelle geometrie pour augmenter le controle sur le nombre d'electrons contenus dans une boite quantique laterale, et ainsi atteindre un regime de petit nombre d'electrons. Ces echantillons permettent une etude du blocage de Coulomb quand les electrons sont injectes a partir d'un gaz electronique a deux dimensions (2DEG). Les mesures a faible champ magnetique demontrent la grande flexibilite des echantillons et montrent que l'on peut faire varier le nombre d'electrons dans une boite quantique a partir de plus de 40 electrons jusqu'a un seul electron, ce qui est assez courant dans les boites quantiques verticales, mais ce qui n'avait jamais ete reussi dans une boite quantique laterale. Nos resultats montrent egalement que dans les boites quantiques laterales il est possible de determiner le spin du niveau qui participe au transport a l'aide du phenomene de blocage de spin. De plus, dans certaines circonstances il est meme possible de determiner le spin total de la boite quantique, ce qui peut avoir des applications pratiques dans des domaines tels l'informatique quantique. Les mesures dans le regime de renversement de spin a un champ magnetique plus eleve montrent l'importance des correlations electrons---electrons dans ces boites quantiques, qui menent a des depolarisations et a des structures de spins qui ont un effet sur le transport. En particulier, ces correlations menent a l'existence de niveaux excites de basse energie qui causent une dependance anormale de l'amplitude des pics de blocage de Coulomb en fonction de la temperature. Nos experiences demontrent egalement la possibilite d'utiliser ces boites quantiques comme sondes pour etudier les proprietes du bord d'un 2DEG. Une voie de recherche a etre exploree.

  14. Nicotinamide enhances repair of ultraviolet radiation-induced DNA damage in primary melanocytes.

    PubMed

    Thompson, Benjamin C; Surjana, Devita; Halliday, Gary M; Damian, Diona L

    2014-07-01

    Cutaneous melanoma is a significant cause of morbidity and mortality. Nicotinamide is a safe, widely available vitamin that reduces the immune suppressive effects of UV, enhances DNA repair in keratinocytes and has shown promise in the chemoprevention of non-melanoma skin cancer. Here, we report the effect of nicotinamide on DNA damage and repair in primary human melanocytes. Nicotinamide significantly enhanced the repair of oxidative DNA damage (8-oxo-7,8-dihydro-2'-deoxyguanosine) and cyclobutane pyrimidine dimers induced by UV exposure. It also enhanced the repair of 8-oxo-7,8-dihydro-2'-deoxyguanosine induced by the culture conditions in unirradiated melanocytes. A significant increase in the percentage of melanocytes undergoing unscheduled but not scheduled DNA synthesis was observed, confirming that nicotinamide enhances DNA repair in human melanocytes. In summary, nicotinamide, by enhancing DNA repair in melanocytes, is a potential agent for the chemoprevention of cutaneous melanoma. PMID:24798949

  15. S100B as a potential biomarker for the detection of cytotoxicity of melanocytes.

    PubMed

    Cheong, Kyung Ah; Noh, Minsoo; Kim, Chang-Hyun; Lee, Ai-Young

    2014-03-01

    Skin irritation is one of the most common adverse reactions in hydroquinone (HQ) and retinoic acid (RA). Although melanocytes have rarely been considered to be involved in skin irritation, RA and particularly HQ could induce melanocyte toxicity, resulting in depigmentation. We chose S100B as a candidate gene for melanocytotoxicity from a genome-wide transcriptional profiling analysis after applying irritant doses of HQ, RA and sodium lauryl sulphate (SLS) to cultures of keratinocytes and/or melanocytes. In this study, the role of S100B on melanocyte viability and cytotoxicity was examined. S100B was detected in melanocytes, but not in keratinocytes or fibroblasts. Melanocytes after treatment with increasing concentrations of HQ, RA, SLS and urushiol showed significant increases in intracellular and extracellular S100B expression with reduced viable cell number and increased release of lactate dehydrogenase. No RAGE expression and no significant function of CD166/ALCAM in melanocyte survival and cytotoxicity favoured the role of intracellular S100B in chemically irritated melanocytes. S100B knock-down increased apoptosis through inhibition of PI3K/AKT, NF-κB and ERK activation, suggesting the increased intracellular S100B expression by chemical irritation as a compensatory reaction to reduce cytotoxicity. The numerical decrease in S100B/c-kit-double-positive melanocytes was also examined in human skin epidermis irritated by HQ or RA with stronger staining intensities of S100B. Collectively, the decrease in viable cell number by reduced intracellular S100B levels in vitro and by chemical irritation in vivo suggests that S100B could be a potential biomarker for melanocytes cytotoxicity. PMID:24451020

  16. La détermination des distances: Sol, Hipparcos, GAIA.

    NASA Astrophysics Data System (ADS)

    Turon, C.

    Les parallaxes trigonométriques des étoiles les plus proches du soleil sont la base de la détermination des distances dans l'Univers. Elles permettent, par la calibration en luminosité des différents indicateurs de distance d'étalonner les distances d'abord dans notre Galaxie, puis dans les galaxies du Groupe Local, puis pour les galaxies plus lointaines. Cette base est, actuellement, très mince, et peu de types d'étoiles y sont représentés. Hipparcos va déjà apporter une amélioration sensible. Avec GAIA une révision complète des calibrations de luminosité de tous les indicateurs "primaires" serait directement possible.

  17. Facteurs associés à la non observance thérapeutique des sujets adultes infectés par le VIH sous antirétroviraux dans un hôpital de référence à Douala

    PubMed Central

    Essomba, Emmanuel Noel; Adiogo, Dieudonné; Koum, Danielle Christiane Kedy; Amang, Baudouin; Lehman, Leopold Gustave; Coppieters, Yves

    2015-01-01

    Introduction Le succès du traitement antirétroviral repose sur l'observance. Elle est nécessaire pour réduire la mortalité, diminuer le risque de résistance et restaurer l'immunité. Cette étude a pour but d'identifier et analyser les différents facteurs associés à la non observance thérapeutique des patients infectés par le VIH sous traitement antirétroviraux à l'hôpital de référence Laquintinie de Douala. Méthodes Il s'agit d'une étude transversale et analytique effectuée de mars à juin 2014. La non observance est mesurée à travers les déclarations du patient et sur consultation des registres de renouvellement des ordonnances. Etaient non observant, ceux ayant consommé moins de 95% de médicaments et ceux ne s’étant pas présentés pour le renouvellement de l'ordonnance. L'analyse bivariée et le modèle de régression logistique ont été utilisés pour la détermination des facteurs associés à la non observance. Résultats Au total, 524 patients ont été enrôlés dans l’étude;l’âge moyen était de 43,0 ± 10,7 ans et le sexe ratio H/F de 0,54. De ces patients, 49,0% étaient non observant, majoritairement des femmes (61,9%). Les principales raisons avancées de la non observance sont: l'oubli (32,9%), la rupture de médicaments (14,0%), les occupations (12,8%). Les personnes veuves(IC 95% OR= 1,31-5,22, p= 0,006), la consommation des excitants (IC 95%, OR= 2,30-6,90, p= 0,0001) et la présence d'infection opportuniste (IC 95%, OR= 1,41-17,54, p= 0,01) ont fortement été associés à la non observance. Conclusion Le taux d'observance était faible, lié à plusieurs facteurs. Des mesures sont nécessaires pour résoudre ce problème, y compris des stratégies tendant à l'amélioration du soutien psycho-social, et la limitation des ruptures de stock de médicaments. La recherche qualitative est souhaitée pour comprendre les raisons de la non observance afin de mettre au point des interventions fondées sur des donn

  18. Endothelin-1 is a transcriptional target of p53 in epidermal keratinocytes and regulates UV induced melanocyte homeostasis

    PubMed Central

    Hyter, Stephen; Coleman, Daniel J.; Ganguli-Indra, Gitali; Merrill, Gary F.; Ma, Steven; Yanagisawa, Masashi; Indra, Arup K.

    2013-01-01

    Summary Keratinocytes contribute to melanocyte activity by influencing their microenvironment, in part, through secretion of paracrine factors. Here we discovered that p53 directly regulates Edn1 expression in epidermal keratinocytes and controls UV-induced melanocyte homeostasis. Selective ablation of EDN1 in murine epidermis (EDN1ep−/−) does not alter melanocyte homeostasis in newborn skin but decreases dermal melanocytes in adult skin. Results showed that keratinocytic EDN1 in a non-cell autonomous manner controls melanocyte proliferation, migration, DNA damage and apoptosis after UVB irradiation. Expression of other keratinocyte derived paracrine factors did not compensate for the loss of EDN1. Topical treatment with EDN1 receptor (EDNRB) antagonist BQ788 abrogated UV induced melanocyte activation and recapitulated the phenotype seen in EDN1ep−/− mice. Altogether, present studies establish an essential role of EDN1 in epidermal keratinocytes to mediate UV induced melanocyte homeostasis in vivo. PMID:23279852

  19. YY1 regulates melanocyte development and function by cooperating with MITF.

    PubMed

    Li, Juying; Song, Jun S; Bell, Robert J A; Tran, Thanh-Nga T; Haq, Rizwan; Liu, Huifei; Love, Kevin T; Langer, Robert; Anderson, Daniel G; Larue, Lionel; Fisher, David E

    2012-01-01

    Studies of coat color mutants have greatly contributed to the discovery of genes that regulate melanocyte development and function. Here, we generated Yy1 conditional knockout mice in the melanocyte-lineage and observed profound melanocyte deficiency and premature gray hair, similar to the loss of melanocytes in human piebaldism and Waardenburg syndrome. Although YY1 is a ubiquitous transcription factor, YY1 interacts with M-MITF, the Waardenburg Syndrome IIA gene and a master transcriptional regulator of melanocytes. YY1 cooperates with M-MITF in regulating the expression of piebaldism gene KIT and multiple additional pigmentation genes. Moreover, ChIP-seq identified genome-wide YY1 targets in the melanocyte lineage. These studies mechanistically link genes implicated in human conditions of melanocyte deficiency and reveal how a ubiquitous factor (YY1) gains lineage-specific functions by co-regulating gene expression with a lineage-restricted factor (M-MITF)-a general mechanism which may confer tissue-specific gene expression in multiple lineages. PMID:22570637

  20. Race Does Not Predict Melanocyte Heterogeneous Responses to Dermal Fibroblast-Derived Mediators

    PubMed Central

    Sirimahachaiyakul, Pornthep; Sood, Ravi F.; Muffley, Lara A.; Seaton, Max; Lin, Cheng-Ta; Qiao, Liang; Armaly, Jeffrey S.; Hocking, Anne M.; Gibran, Nicole S.

    2015-01-01

    Introduction Abnormal pigmentation following cutaneous injury causes significant patient distress and represents a barrier to recovery. Wound depth and patient characteristics influence scar pigmentation. However, we know little about the pathophysiology leading to hyperpigmentation in healed shallow wounds and hypopigmentation in deep dermal wound scars. We sought to determine whether dermal fibroblast signaling influences melanocyte responses. Methods and Materials Epidermal melanocytes from three Caucasians and three African-Americans were genotyped for single nucleotide polymorphisms (SNPs) across the entire genome. Melanocyte genetic profiles were determined using principal component analysis. We assessed melanocyte phenotype and gene expression in response to dermal fibroblast-conditioned medium and determined potential mesenchymal mediators by proteome profiling the fibroblast-conditioned medium. Results Six melanocyte samples demonstrated significant variability in phenotype and gene expression at baseline and in response to fibroblast-conditioned medium. Genetic profiling for SNPs in receptors for 13 identified soluble fibroblast-secreted mediators demonstrated considerable heterogeneity, potentially explaining the variable melanocyte responses to fibroblast-conditioned medium. Discussion Our data suggest that melanocytes respond to dermal fibroblast-derived mediators independent of keratinocytes and raise the possibility that mesenchymal-epidermal interactions influence skin pigmentation during cutaneous scarring. PMID:26418010

  1. RICTOR involvement in the PI3K/AKT pathway regulation in melanocytes and melanoma

    PubMed Central

    Laugier, Florence; Finet-Benyair, Adeline; André, Jocelyne; Rachakonda, P. Sivaramakrishna; Kumar, Rajiv; Bensussan, Armand; Dumaz, Nicolas

    2015-01-01

    Several studies have highlighted the importance of the PI3K pathway in melanocytes and its frequent over-activation in melanoma. However, little is known about regulation of the PI3K pathway in melanocytic cells. We showed that normal human melanocytes are less sensitive to selective PI3K or mTOR inhibitors than to dual PI3K/mTOR inhibitors. The resistance to PI3K inhibitor was due to a rapid AKT reactivation limiting the inhibitor effect on proliferation. Reactivation of AKT was linked to a feedback mechanism involving the mTORC2 complex and in particular its scaffold protein RICTOR. RICTOR overexpression in melanocytes disrupted the negative feedback, activated the AKT pathway and stimulated clonogenicity highlighting the importance of this feedback to restrict melanocyte proliferation. We found that the RICTOR locus is frequently amplified and overexpressed in melanoma and that RICTOR over-expression in NRAS-transformed melanocytes stimulates their clonogenicity, demonstrating that RICTOR amplification can cooperate with NRAS mutation to stimulate melanoma proliferation. These results show that RICTOR plays a central role in PI3K pathway negative feedback in melanocytes and that its deregulation could be involved in melanoma development. PMID:26356562

  2. Human melanocytes mitigate keratinocyte-dependent contraction in an in vitro collagen contraction assay.

    PubMed

    Rakar, Jonathan; Krammer, Markus P; Kratz, Gunnar

    2015-08-01

    Scarring is an extensive problem in burn care, and treatment can be especially complicated in cases of hypertrophic scarring. Contraction is an important factor in scarring but the contribution of different cell types remains unclear. We have investigated the contractile behavior of keratinocytes, melanocytes and fibroblasts by using an in vitro collagen gel assay aimed at identifying a modulating role of melanocytes in keratinocyte-mediated contraction. Cells were seeded on a collagen type I gel substrate and the change in gel dimensions were measured over time. Hematoxylin & Eosin-staining and immunohistochemistry against pan-cytokeratin and microphthalmia-associated transcription factor showed that melanocytes integrated between keratinocytes and remained there throughout the experiments. Keratinocyte- and fibroblast-seeded gels contracted significantly over time, whereas melanocyte-seeded gels did not. Co-culture assays showed that melanocytes mitigate the keratinocyte-dependent contraction (significantly slower and 18-32% less). Fibroblasts augmented the contraction in most assays (approximately 6% more). Non-contact co-cultures showed some influence on the keratinocyte-dependent contraction. Results show that mechanisms attributable to melanocytes, but not fibroblasts, can mitigate keratinocyte contractile behavior. Contact-dependent mechanisms are stronger modulators than non-contact dependent mechanisms, but both modes carry significance to the contraction modulation of keratinocytes. Further investigations are required to determine the mechanisms involved and to determine the utility of melanocytes beyond hypopigmentation in improved clinical regimes of burn wounds and wound healing. PMID:25466959

  3. In ovo gene manipulation of melanocytes and their adjacent keratinocytes during skin pigmentation of chicken embryos.

    PubMed

    Murai, Hidetaka; Tadokoro, Ryosuke; Sakai, Ken-Ichiro; Takahashi, Yoshiko

    2015-04-01

    During skin pigmentation in avians and mammalians, melanin is synthesized in the melanocytes, and subsequently transferred to adjacently located keratinocytes, leading to a wide coverage of the body surface by melanin-containing cells. The behavior of melanocytes is influenced by keratinocytes shown mostly by in vitro studies. However, it has poorly been investigated how such intercellular cross-talk is regulated in vivo because of a lack of suitable experimental models. Using chicken embryos, we developed a method that enables in vivo gene manipulations of melanocytes and keratinocytes, where these cells are separately labeled by different genes. Two types of gene transfer techniques were combined: one was a retrovirus-mediated gene infection into the skin/keratinocytes, and the other was the in ovo DNA electroporation into neural crest cells, the origin of melanocytes. Since the Replication-Competent Avian sarcoma-leukosis virus long terminal repeat with Splice acceptor (RCAS) infection was available only for the White leghorn strain showing little pigmentation, melanocytes prepared from the Hypeco nera (pigmented) were back-transplanted into embryos of White leghorn. Prior to the transplantation, enhanced green fluorescent protein (EGFP)(+) Neo(r+) -electroporated melanocytes from Hypeco nera were selectively grown in G418-supplemented medium. In the skin of recipient White leghorn embryos infected with RCAS-mOrange, mOrange(+) keratinocytes and transplanted EGFP(+) melanocytes were frequently juxtaposed each other. High-resolution confocal microscopy also revealed that transplanted melanocytes exhibited normal behaviors regarding distribution patterns of melanocytes, dendrite morphology, and melanosome transfer. The method described in this study will serve as a useful tool to understand the mechanisms underlying intercellular regulations during skin pigmentation in vivo. PMID:25739909

  4. Microphthalmia-associated transcription factor as the molecular target of cadmium toxicity in human melanocytes

    SciTech Connect

    Chantarawong, Wipa; Takeda, Kazuhisa; Sangartit, Weerapon; Yoshizawa, Miki; Pradermwong, Kantimanee; Shibahara, Shigeki

    2014-11-28

    Highlights: • In human melanocytes, cadmium decreases the expression of MITF-M and tyrosinase and their mRNAs. • In human melanoma cells, cadmium decreases the expression of MITF-M protein and tyrosinase mRNA. • Expression of MITF-H is less sensitive to cadmium toxicity in melanocyte-linage cells. • Cadmium does not decrease the expression of MITF-H in retinal pigment epithelial cells. • MITF-M is the molecular target of cadmium toxicity in melanocytes. - Abstract: Dietary intake of cadmium is inevitable, causing age-related increase in cadmium accumulation in many organs, including hair, choroid and retinal pigment epithelium (RPE). Cadmium has been implicated in the pathogenesis of hearing loss and macular degeneration. The functions of cochlea and retina are maintained by melanocytes and RPE, respectively, and the differentiation of these pigment cells is regulated by microphthalmia-associated transcription factor (MITF). In the present study, we explored the potential toxicity of cadmium in the cochlea and retina by using cultured human melanocytes and human RPE cell lines. MITF consists of multiple isoforms, including melanocyte-specific MITF-M and widely expressed MITF-H. Levels of MITF-M protein and its mRNA in human epidermal melanocytes and HMV-II melanoma cells were decreased significantly by cadmium. In parallel with the MITF reduction, mRNA levels of tyrosinase, the key enzyme of melanin biosynthesis that is regulated by MITF-M, were also decreased. In RPE cells, however, the levels of total MITF protein, constituting mainly MITF-H, were not decreased by cadmium. We thus identify MITF-M as the molecular target of cadmium toxicity in melanocytes, thereby accounting for the increased risk of disability from melanocyte malfunction, such as hearing and vision loss among people with elevated cadmium exposure.

  5. Intérêt de l'inspection visuelle à l'acide acétique et au soluté de Lugol avec colposcope dans le dépistage des lésions du col utérin au Gabon

    PubMed Central

    Mpiga, Édith; Ivanga, Mahinè; Koumakpayi, Ismaël Hervé; Engohan-Aloghe, Corinne; Ankély, Junie Chansi; Belembaogo, Ernest; Meye, Jean-François

    2015-01-01

    Introduction Au Gabon, le dépistage des lésions précancéreuses et cancéreuses du col de l'utérus n'est pas systématique. La vulgarisation de ce dépistage suppose l'utilisation d'un test efficace et adapté aux réalités locales. Méthodes L'objectif de cette étude était de comparer les performances du frottis cervico-vaginal (FCV) conventionnel et de l'inspection visuelle à l'acide acétique (IVA) et au soluté de Lugol (IVL) couplée à la colposcopie, dans la détection des lésions du col utérin au Gabon. Des tests IVA/IVL et FCV ont été effectués chez 309 femmes gabonaises âgées de 18 à 75 ans. Des biopsies ont été réalisées en cas de résultat positif. Résultats 5 cancers épidermoïdes (1,6%) et 4 lésions précancéreuses (1,3%) ont été confirmées par l'histologie. L'IVA/IVL a présenté une meilleure sensibilité (100%) que le FCV (89%). Toutefois, le FCV est apparu plus spécifique (100% versus 92%). Avec une valeur prédictive (VP) négative de 100%, l'IVA/IVL a permis d'exclure avec certitude la présence de cancer du col lorsque le résultat était négatif, contrairement au FCV (92%). L'IVA/IVL et le FCV ont présenté des VP positives respectivement de 90% et 100%. Conclusion Cette étude montre que l'IVA/IVL avec colposcope couplée à l'histologie en cas de résultat positif apparaît plus performante que le FCV. PMID:26893799

  6. Vers des boites quantiques a base de graphene

    NASA Astrophysics Data System (ADS)

    Branchaud, Simon

    Le graphene est un materiau a base de carbone qui est etudie largement depuis 2004. De tres nombreux articles ont ete publies tant sur les proprietes electroniques, qu'optiques ou mecaniques de ce materiel. Cet ouvrage porte sur l'etude des fluctuations de conductance dans le graphene, et sur la fabrication et la caracterisation de nanostructures gravees dans des feuilles de ce cristal 2D. Des mesures de magnetoresistance a basse temperature ont ete faites pres du point de neutralite de charge (PNC) ainsi qu'a haute densite electronique. On trouve deux origines aux fluctuations de conductance pres du PNC, soit des oscillations mesoscopiques provenant de l'interference quantique, et des fluctuations dites Hall quantique apparaissant a plus haut champ (>0.5T), semblant suivre les facteurs de remplissage associes aux monocouches de graphene. Ces dernieres fluctuations sont attribuees a la charge d'etats localises, et revelent un precurseur a l'effet Hall quantique, qui lui, ne se manifeste pas avant 2T. On arrive a extraire les parametres caracterisant l'echantillon a partir de ces donnees. A la fin de cet ouvrage, on effectue des mesures de transport dans des constrictions et ilots de graphene, ou des boites quantiques sont formees. A partir de ces mesures, on extrait les parametres importants de ces boites quantiques, comme leur taille et leur energie de charge.

  7. Implantation des sites de soins communautaires en République Démocratique du Congo: consécration d'un double standard dans l'accès aux soins

    PubMed Central

    Dunia, Gisèle Mawazo Binti

    2013-01-01

    Depuis 2005, la République Démocratique du Congo a amorcé l'implantation des sites de soins communautaires. Cette stratégie a pour objectif de rapprocher les services de santé des populations éloignées. Bien que cela parte d'une bonne intention, elle résulte, à notre sens, en une consécration d'un système de santé à deux vitesses. En effet, les populations vivant en ville ont accès à des soins prestés par des agents de santé formés alors que celles vivant en milieu rural reculé ont pour prestataires de soins des relais communautaires. Cette situation marginalise encore plus des populations dont la situation géographique est déjà préoccupante. Pourtant, la population est prête à parcourir des kilomètres en échange d'un service qu'elle estime de qualité. PMID:23785563

  8. Des Vents et des Jets Astrophysiques

    NASA Astrophysics Data System (ADS)

    Sauty, C.

    well expected result from the theory. Although, collimation may be conical, paraboloidal or cylindrical (Part 4), cylindrical collimation is the more likely to occur. The shape of outflows may then be used as a tool to predict physical conditions on the flows or on their source. L'éjection continue de plasma autour d'objets massifs est un phénomène largement répandu en astrophysique, que ce soit sous la forme du vent solaire, de vents stellaires, de jets d'étoiles en formation, de jets stellaires autour d'objets compacts ou de jets extra-galactiques. Cette zoologie diversifiée fait pourtant l'objet d'un commun effort de modélisation. Le but de cette revue est d'abord de présenter qualitativement le développement, depuis leur origine, des diverses théories de vents (Partie 1) et l'inter disciplinarité dans ce domaine. Il s'agit d'une énumération, plus ou moins exhaustive, des idées proposées pour expliquer l'accélération et la morphologie des vents et des jets, accompagnée d'une présentation sommaire des aspects observationnels. Cette partie s'abstient de tout aspect faisant appel au formalisme mathématique. Ces écoulements peuvent être décrits, au moins partiellement, en résolvant les équations magnétohydrodynamiques, axisymétriques et stationnaires. Ce formalisme, à la base de la plupart des théories, est exposé dans la Partie 2. Il permet d'introduire quantitativement les intégrales premières qu'un tel système possède. Ces dernières sont amenées à jouer un rôle important dans la compréhension des phénomènes d'accélération ou de collimation, en particulier le taux de perte de masse, le taux de perte de moment angulaire ou l'énergie du rotateur magnétique. La difficulté de modélisation réside dans l'existence de points critiques, propres aux équations non linéaires, qu'il faut franchir. La nature physique et la localisation de ces points critiques fait l'objet d'un débat important car ils sont la clef de voute de la r

  9. Treatment of congenital melanocytic naevi with CO2 laser.

    PubMed

    Horner, Ben M; El-Muttardi, Naguib S; Mayou, Bryan J

    2005-09-01

    This study assesses the effectiveness of CO2 laser in treating congenital melanocytic naevi (CMN). A retrospective review of 12 patients with CMN treated with CO2 laser was carried out. In all cases, there was minimal visible naevus after treatment. Six patients developed hypertrophic scarring; this was significantly more likely following CO2 laser treatment on the anterior torso, flanks, or arms than on the back or buttocks (P = 0.01, 1-tailed Fisher exact test). We conclude that CO2 laser is an effective treatment for reducing visible pigmentation of CMN. However, it can cause hypertrophic scarring, which has not been reported before. This risk can be reduced by limited use in areas of the body where the dermis is thinner or there is a known risk of hypertrophic scarring. In addition, the cautious use of paint mode and prophylactic use of pressure or silicon dressings may also reduce the risk of hypertrophic scarring. PMID:16106167

  10. Fiabilité des structures mécaniques adaptatives: effet de la panne des actionneurs ou des capteurs sur la stabilité

    NASA Astrophysics Data System (ADS)

    Fall, H.; Charon, W.; Kouta, R.

    2002-12-01

    Ces dernières décennies, des activités significatives dans le monde étaient dirigées autour du contrôle actif. Le but de ces recherches était essentiellement d'améliorer les performances, la fiabilité et la sécurité des systèmes. Notamment dans le cas des structures soumises à des vibrations aléatoires. D'importants travaux ont été consacré à l'utilisation des “matériaux intelligents” comme capteurs et actionneurs. Cette article propose l'analyse de la fiabilité des systèmes mécaniques en étudiant les pannes des actionneurs ou des capteurs. L'effet de ces pannes sur la stabilité et la performance du système y est démontré. Les méthodologies de conception y sont rappelées. Des exemples numériques sont fournis à travers le contrôle d'un panneau sous chargement dynamique pour illustrer la méthode proposée.

  11. Médecine des voyages

    PubMed Central

    Aw, Brian; Boraston, Suni; Botten, David; Cherniwchan, Darin; Fazal, Hyder; Kelton, Timothy; Libman, Michael; Saldanha, Colin; Scappatura, Philip; Stowe, Brian

    2014-01-01

    Résumé Objectif Définir la pratique de la médecine des voyages, présenter les éléments fondamentaux d’une consultation complète préalable aux voyages à des voyageurs internationaux et aider à identifier les patients qu’il vaudrait mieux envoyer en consultation auprès de professionnels de la médecine des voyages. Sources des données Les lignes directrices et les recommandations sur la médecine des voyages et les maladies liées aux voyages publiées par les autorités sanitaires nationales et internationales ont fait l’objet d’un examen. Une recension des ouvrages connexes dans MEDLINE et EMBASE a aussi été effectuée. Message principal La médecine des voyages est une spécialité très dynamique qui se concentre sur les soins préventifs avant un voyage. Une évaluation exhaustive du risque pour chaque voyageur est essentielle pour mesurer avec exactitude les risques particuliers au voyageur, à son itinéraire et à sa destination et pour offrir des conseils sur les interventions les plus appropriées en gestion du risque afin de promouvoir la santé et prévenir les problèmes médicaux indésirables durant le voyage. Des vaccins peuvent aussi être nécessaires et doivent être personnalisés en fonction des antécédents d’immunisation du voyageur, de son itinéraire et du temps qu’il reste avant son départ. Conclusion La santé et la sécurité d’un voyageur dépendent du degré d’expertise du médecin qui offre le counseling préalable à son voyage et les vaccins, au besoin. On recommande à ceux qui donnent des conseils aux voyageurs d’être conscients de l’ampleur de cette responsabilité et de demander si possible une consultation auprès de professionnels de la médecine des voyages pour tous les voyageurs à risque élevé.

  12. Direct conversion of mouse and human fibroblasts to functional melanocytes by defined factors.

    PubMed

    Yang, Ruifeng; Zheng, Ying; Li, Ling; Liu, Shujing; Burrows, Michelle; Wei, Zhi; Nace, Arben; Herlyn, Meenhard; Cui, Rutao; Guo, Wei; Cotsarelis, George; Xu, Xiaowei

    2014-01-01

    Direct reprogramming provides a fundamentally new approach for the generation of patient-specific cells. Here, by screening a pool of candidate transcription factors, we identify that a combination of the three factors, MITF, SOX10 and PAX3, directly converts mouse and human fibroblasts to functional melanocytes. Induced melanocytes (iMels) activate melanocyte-specific networks, express components of pigment production and delivery system and produce melanosomes. Human iMels properly integrate into the dermal-epidermal junction and produce and deliver melanin pigment to surrounding keratinocytes in a 3D organotypic skin reconstruct. Human iMels generate pigmented epidermis and hair follicles in skin reconstitution assays in vivo. The generation of iMels has important implications for studies of melanocyte lineage commitment, pigmentation disorders and cell replacement therapies. PMID:25510211

  13. EdnrB Governs Regenerative Response of Melanocyte Stem Cells by Crosstalk with Wnt Signaling.

    PubMed

    Takeo, Makoto; Lee, Wendy; Rabbani, Piul; Sun, Qi; Hu, Hai; Lim, Chae Ho; Manga, Prashiela; Ito, Mayumi

    2016-05-10

    Delineating the crosstalk between distinct signaling pathways is key to understanding the diverse and dynamic responses of adult stem cells during tissue regeneration. Here, we demonstrate that the Edn/EdnrB signaling pathway can interact with other signaling pathways to elicit distinct stem cell functions during tissue regeneration. EdnrB signaling promotes proliferation and differentiation of melanocyte stem cells (McSCs), dramatically enhancing the regeneration of hair and epidermal melanocytes. This effect is dependent upon active Wnt signaling that is initiated by Wnt ligand secretion from the hair follicle epithelial niche. Further, this Wnt-dependent EdnrB signaling can rescue the defects in melanocyte regeneration caused by Mc1R loss. This suggests that targeting Edn/EdnrB signaling in McSCs can be a therapeutic approach to promote photoprotective-melanocyte regeneration, which may be useful for those with increased risk of skin cancers due to Mc1R variants. PMID:27134165

  14. Differential diagnosis of heavily pigmented melanocytic lesions: challenges and diagnostic approach.

    PubMed

    Aung, Phyu P; Mutyambizi, Kudakwashe K; Danialan, Richard; Ivan, Doina; Prieto, Victor G

    2015-12-01

    The differential diagnosis of heavily pigmented melanocytic neoplasms includes melanoma (especially animal type), melanosis of partially or completely regressed melanoma, blue naevus (BN), pigmented Spitzoid lesions, recurrent naevus, combined naevus, pigmented spindle cell naevus, epithelioid blue naevus of the Carney complex/pigmented epithelioid melanocytoma, deep penetrating naevus, hyperpigmented scar after surgery of melanoma in which there are also melanophages and hyperpigmentation due to the minocycline, a tattoo or a hyperpigmented scar. Pathologists face challenges when evaluating a pigmented lesion, especially in a small superficial biopsy, because it is difficult to access important histopathological features to differentiate benign versus malignant melanocytic lesions. The histological features that favour a diagnosis of melanoma include dimension (>6 mm), asymmetry, poor circumscription, irregular confluent nests, confluent lentiginous junctional melanocytic proliferation, lack of maturation with descent in the dermis, suprabasal pagetoid melanocytes, asymmetrical distribution of melanin pigment, cytological atypia, dermal mitotic figures, asymmetrical dermal lymphocytic infiltrate and necrosis. PMID:26602414

  15. Direct conversion of mouse and human fibroblasts to functional melanocytes by defined factors

    PubMed Central

    Yang, Ruifeng; Zheng, Ying; Li, Ling; Liu, Shujing; Burrows, Michelle; Wei, Zhi; Nace, Arben; Herlyn, Meenhard; Cui, Rutao; Guo, Wei; Cotsarelis, George; Xu, Xiaowei

    2015-01-01

    Direct reprogramming provides a fundamentally new approach for the generation of patient-specific cells. Here, by screening a pool of candidate transcription factors, we identify that a combination of three factors, MITF, SOX10 and PAX3, directly converts mouse and human fibroblasts to functional melanocytes. Induced melanocytes (iMels) activate melanocyte-specific networks, express components of pigment production and delivery system, and produce melanosomes. Human iMels properly integrate into the dermal-epidermal junction, and produce and deliver melanin pigment to surrounding keratinocytes in a 3D organotypic skin reconstruct. Human iMels generate pigmented epidermis and hair follicles in skin reconstitution assays in vivo. The generation of iMels has important implications for studies of melanocyte lineage commitment, pigmentation disorders and cell replacement therapies. PMID:25510211

  16. NF1 loss induces senescence during human melanocyte differentiation in an iPSC-based model.

    PubMed

    Larribere, Lionel; Wu, Huizi; Novak, Daniel; Galach, Marta; Bernhardt, Mathias; Orouji, Elias; Weina, Kasia; Knappe, Nathalie; Sachpekidis, Christos; Umansky, Ludmila; Beckhove, Philipp; Umansky, Viktor; De Schepper, Sofie; Kaufmann, Dieter; Ballotti, Robert; Bertolotto, Corine; Utikal, Jochen

    2015-07-01

    Neurofibromatosis type 1 (NF1) is a frequent genetic disease leading to the development of Schwann cell-derived neurofibromas or melanocytic lesions called café-au-lait macules (CALMs). The molecular mechanisms involved in CALMs formation remain largely unknown. In this report, we show for the first time pathophysiological mechanisms of abnormal melanocyte differentiation in a human NF1(+/-) -induced pluripotent stem cell (iPSC)-based model. We demonstrate that NF1 patient-derived fibroblasts can be successfully reprogrammed in NF1(+/-) iPSCs with active RAS signaling and that NF1 loss induces senescence during melanocyte differentiation as well as in patient's-derived CALMs, revealing a new role for NF1 in the melanocyte lineage. PMID:25824590

  17. NFIB is a governor of epithelial–melanocyte stem cell behaviour in a shared niche

    PubMed Central

    Chang, Chiung-Ying; Pasolli, H. Amalia; Giannopoulou, Eugenia G.; Guasch, Géraldine; Gronostajski, Richard M.; Elemento, Olivier; Fuchs, Elaine

    2013-01-01

    Adult stem cells reside in specialized niches where they receive environmental cues to maintain tissue homeostasis. In mammals, the stem cell niche within hair follicles is home to epithelial hair follicle stem cells and melanocyte stem cells, which sustain cyclical bouts of hair regeneration and pigmentation1–4. To generate pigmented hairs, synchrony is achieved such that upon initiation of a new hair cycle, stem cells of each type activate lineage commitment2,5. Dissecting the inter-stem-cell crosstalk governing this intricate coordination has been difficult, because mutations affecting one lineage often affect the other. Here we identify transcription factor NFIB as an unanticipated coordinator of stem cell behaviour. Hair follicle stem-cell-specific conditional targeting of Nfib in mice uncouples stem cell synchrony. Remarkably, this happens not by perturbing hair cycle and follicle architecture, but rather by promoting melanocyte stem cell proliferation and differentiation. The early production of melanin is restricted to melanocyte stem cells at the niche base. Melanocyte stem cells more distant from the dermal papilla are unscathed, thereby preventing hair greying typical of melanocyte stem cell differentiation mutants. Furthermore, we pinpoint KIT-ligand as a dermal papilla signal promoting melanocyte stem cell differentiation. Additionally, through chromatin-immunoprecipitation with high-throughput-sequencing and transcriptional profiling, we identify endothelin 2 (Edn2) as an NFIB target aberrantly activated in NFIB-deficient hair follicle stem cells. Ectopically induced Edn2 recapitulates NFIB-deficient phenotypes in wild-type mice. Conversely, endothelin receptor antagonists and/or KIT blocking antibodies prevent precocious melanocyte stem cell differentiation in the NFIB-deficient niche. Our findings reveal how melanocyte and hair follicle stem cell behaviours maintain reliance upon cooperative factors within the niche, and how this can be uncoupled

  18. NFIB is a governor of epithelial-melanocyte stem cell behaviour in a shared niche.

    PubMed

    Chang, Chiung-Ying; Pasolli, H Amalia; Giannopoulou, Eugenia G; Guasch, Géraldine; Gronostajski, Richard M; Elemento, Olivier; Fuchs, Elaine

    2013-03-01

    Adult stem cells reside in specialized niches where they receive environmental cues to maintain tissue homeostasis. In mammals, the stem cell niche within hair follicles is home to epithelial hair follicle stem cells and melanocyte stem cells, which sustain cyclical bouts of hair regeneration and pigmentation. To generate pigmented hairs, synchrony is achieved such that upon initiation of a new hair cycle, stem cells of each type activate lineage commitment. Dissecting the inter-stem-cell crosstalk governing this intricate coordination has been difficult, because mutations affecting one lineage often affect the other. Here we identify transcription factor NFIB as an unanticipated coordinator of stem cell behaviour. Hair follicle stem-cell-specific conditional targeting of Nfib in mice uncouples stem cell synchrony. Remarkably, this happens not by perturbing hair cycle and follicle architecture, but rather by promoting melanocyte stem cell proliferation and differentiation. The early production of melanin is restricted to melanocyte stem cells at the niche base. Melanocyte stem cells more distant from the dermal papilla are unscathed, thereby preventing hair greying typical of melanocyte stem cell differentiation mutants. Furthermore, we pinpoint KIT-ligand as a dermal papilla signal promoting melanocyte stem cell differentiation. Additionally, through chromatin-immunoprecipitation with high-throughput-sequencing and transcriptional profiling, we identify endothelin 2 (Edn2) as an NFIB target aberrantly activated in NFIB-deficient hair follicle stem cells. Ectopically induced Edn2 recapitulates NFIB-deficient phenotypes in wild-type mice. Conversely, endothelin receptor antagonists and/or KIT blocking antibodies prevent precocious melanocyte stem cell differentiation in the NFIB-deficient niche. Our findings reveal how melanocyte and hair follicle stem cell behaviours maintain reliance upon cooperative factors within the niche, and how this can be uncoupled in

  19. Sensitivity of mouse Skh:HR-2 to ultraviolet radiation: melanocyte inactivation

    SciTech Connect

    Warren, R.; Gardner, P.A.; Reed, J.C.

    1987-03-01

    The hairless mouse, Skh:HR-2, was exposed to doses of ultraviolet (UV) radiation known to induce skin pigmentation. Three parameters associated with perturbations in skin pigmentation were monitored following UV exposure. These include spectroscopy (skin darkness), histology (melanocyte density), and biochemistry (melanin). Within 90 min of UV exposure, the skin became lighter. This was associated with a reduction of quantifiable melanin and the inactivation of epidermal melanocytes.

  20. Cooperative response of keratinocytes and melanocytes to UV radiation during PUVA therapy

    NASA Astrophysics Data System (ADS)

    Stolnitz, Mikhail M.; Baskakov, Pavel V.; Peshkova, Anna Y.

    1999-03-01

    The mathematical model of processes in UV-irradiated furocoumarin-sensitized epidermis is presented taking into account the mutual influence of keratinocytes and melanocytes populations. The model describes epidermis as a hierarchical structure on tissue (keratinocytes-melanocytes cooperation, melanin screen formation), cellular (proliferation and differentiation, transitions between subpopulations), subcellular (cell movement on mitotic cycle, generation, maturing and migration of melanosomes), and molecular (melanin synthesis, processes of DNA damage and repair, molecular signal transduction) levels.

  1. Complete regression of a melanocytic nevus after epilation with diode laser therapy

    PubMed Central

    Boleira, Manuela; de Almeida Balassiano, Laila Klotz; Jeunon3, Thiago

    2015-01-01

    The use of lasers and intense pulsed light (IPL) technology has become an established practice in dermatology and aesthetic medicine. The use of laser therapy and IPL in the treatment of pigmented melanocytic lesions is a controversial issue. We report clinical, dermoscopic and histological changes of a completely regressed pigmented melanocytic nevus after hair removal treatment with the LightSheer™ Diode Laser (Lumenis Ltd, Yokneam, Israel). PMID:26114064

  2. Image enhancement of optical images for binary system of melanocytes and keratinocytes

    NASA Astrophysics Data System (ADS)

    Takanezawa, S.; Baba, A.; Sako, Y.; Ozaki, Y.; Date, A.; Toyama, K.; Morita, S.

    2013-05-01

    Automatic determination of the cell shapes of large numbers of melanocytes based on optical images of human skin models have been largely unsuccessful (the complexities introduced by dendrites and the melanin pigmentation over the keratinocytes to give unclear outlines). Here, we present an image enhancement procedure for enhancing the contrast of images with removing the non-uniformity of background. The brightness is normalized also for the non-uniform population density of melanocytes.

  3. Prostaglandin E{sub 2} regulates melanocyte dendrite formation through activation of PKC{zeta}

    SciTech Connect

    Scott, Glynis Fricke, Alex; Fender, Anne; McClelland, Lindy; Jacobs, Stacey

    2007-11-01

    Prostaglandins are lipid signaling intermediates released by keratinocytes in response to ultraviolet irradiation (UVR) in the skin. The main prostaglandin released following UVR is PGE{sub 2}, a ligand for 4 related G-protein-coupled receptors (EP{sub 1}, EP{sub 2}, EP{sub 3} and EP{sub 4}). Our previous work established that PGE{sub 2} stimulates melanocyte dendrite formation through activation of the EP{sub 1} and EP{sub 3} receptors. The purpose of the present report is to define the signaling intermediates involved in EP{sub 1}- and EP{sub 3}-dependent dendrite formation in human melanocytes. We recently showed that activation of the atypical PKC{zeta} isoform stimulates melanocyte dendricity in response to treatment with lysophosphatidylcholine. We therefore examined the potential contribution of PKC{zeta} activation on EP{sub 1}- and EP{sub 3}-dependent dendrite formation in melanocytes. Stimulation of the EP{sub 1} and EP{sub 3} receptors by selective agonists activated PKC{zeta}, and inhibition of PKC{zeta} activation abrogated EP{sub 1}- and EP{sub 3}-receptor-mediated melanocyte dendricity. Because of the importance of Rho-GTP binding proteins in the regulation of melanocyte dendricity, we also examined the effect of EP{sub 1} and EP{sub 3} receptor activation on Rac and Rho activity. Neither Rac nor Rho was activated upon treatment with EP{sub 1,3}-receptor agonists. We show that melanocytes express only the EP{sub 3A1} isoform, but not the EP{sub 3B} receptor isoform, previously associated with Rho activation, consistent with a lack of Rho stimulation by EP{sub 3} agonists. Our data suggest that PKC{zeta} activation plays a predominant role in regulation of PGE{sub 2}-dependent melanocyte dendricity.

  4. Nitric oxide enhances the sensitivity of alpaca melanocytes to respond to {alpha}-melanocyte-stimulating hormone by up-regulating melanocortin-1 receptor

    SciTech Connect

    Dong, Yanjun; Cao, Jing; Wang, Haidong; Zhang, Jie; Zhu, Zhiwei; Bai, Rui; Hao, HuanQing; He, Xiaoyan; Fan, Ruiwen; Dong, Changsheng

    2010-06-11

    Nitric oxide (NO) and {alpha}-melanocyte-stimulating hormone ({alpha}-MSH) have been correlated with the synthesis of melanin. The NO-dependent signaling of cellular response to activate the hypothalamopituitary proopiomelanocortin system, thereby enhances the hypophysial secretion of {alpha}-MSH to stimulate {alpha}-MSH-receptor responsive cells. In this study we investigated whether an NO-induced pathway can enhance the ability of the melanocyte to respond to {alpha}-MSH on melanogenesis in alpaca skin melanocytes in vitro. It is important for us to know how to enhance the coat color of alpaca. We set up three groups for experiments using the third passage number of alpaca melanocytes: the control cultures were allowed a total of 5 days growth; the UV group cultures like the control group but the melanocytes were then irradiated everyday (once) with 312 mJ/cm{sup 2} of UVB; the UV + L-NAME group is the same as group UV but has the addition of 300 {mu}M L-NAME (every 6 h). To determine the inhibited effect of NO produce, NO produces were measured. To determine the effect of the NO to the key protein and gene of {alpha}-MSH pathway on melanogenesis, the key gene and protein of the {alpha}-MSH pathway were measured by quantitative real-time PCR and Western immunoblotting. The results provide exciting new evidence that NO can enhance {alpha}-MSH pathway in alpaca skin melanocytes by elevated MC1R. And we suggest that the NO pathway may more rapidly cause the synthesis of melanin in alpaca skin under UV, which at that time elevates the expression of MC1R and stimulates the keratinocytes to secrete {alpha}-MSH to enhance the {alpha}-MSH pathway on melanogenesis. This process will be of considerable interest in future studies.

  5. Understanding Melanocyte Stem Cells for Disease Modeling and Regenerative Medicine Applications

    PubMed Central

    Mull, Amber N.; Zolekar, Ashwini; Wang, Yu-Chieh

    2015-01-01

    Melanocytes in the skin play an indispensable role in the pigmentation of skin and its appendages. It is well known that the embryonic origin of melanocytes is neural crest cells. In adult skin, functional melanocytes are continuously repopulated by the differentiation of melanocyte stem cells (McSCs) residing in the epidermis of the skin. Many preceding studies have led to significant discoveries regarding the cellular and molecular characteristics of this unique stem cell population. The alteration of McSCs has been also implicated in several skin abnormalities and disease conditions. To date, our knowledge of McSCs largely comes from studying the stem cell niche of mouse hair follicles. Suggested by several anatomical differences between mouse and human skin, there could be distinct features associated with mouse and human McSCs as well as their niches in the skin. Recent advances in human pluripotent stem cell (hPSC) research have provided us with useful tools to potentially acquire a substantial amount of human McSCs and functional melanocytes for research and regenerative medicine applications. This review highlights recent studies and progress involved in understanding the development of cutaneous melanocytes and the regulation of McSCs. PMID:26703580

  6. Microphthalmia-associated transcription factor as the molecular target of cadmium toxicity in human melanocytes.

    PubMed

    Chantarawong, Wipa; Takeda, Kazuhisa; Sangartit, Weerapon; Yoshizawa, Miki; Pradermwong, Kantimanee; Shibahara, Shigeki

    2014-11-28

    Dietary intake of cadmium is inevitable, causing age-related increase in cadmium accumulation in many organs, including hair, choroid and retinal pigment epithelium (RPE). Cadmium has been implicated in the pathogenesis of hearing loss and macular degeneration. The functions of cochlea and retina are maintained by melanocytes and RPE, respectively, and the differentiation of these pigment cells is regulated by microphthalmia-associated transcription factor (MITF). In the present study, we explored the potential toxicity of cadmium in the cochlea and retina by using cultured human melanocytes and human RPE cell lines. MITF consists of multiple isoforms, including melanocyte-specific MITF-M and widely expressed MITF-H. Levels of MITF-M protein and its mRNA in human epidermal melanocytes and HMV-II melanoma cells were decreased significantly by cadmium. In parallel with the MITF reduction, mRNA levels of tyrosinase, the key enzyme of melanin biosynthesis that is regulated by MITF-M, were also decreased. In RPE cells, however, the levels of total MITF protein, constituting mainly MITF-H, were not decreased by cadmium. We thus identify MITF-M as the molecular target of cadmium toxicity in melanocytes, thereby accounting for the increased risk of disability from melanocyte malfunction, such as hearing and vision loss among people with elevated cadmium exposure. PMID:25449283

  7. Alpha-melanocyte stimulating hormone inhibits monocytes adhesion to vascular endothelium.

    PubMed

    Yang, Yang; Zhang, Weihua; Meng, Lin; Yu, Haitao; Lu, Na; Fu, Gang; Zheng, Yang

    2015-11-01

    Inflammation and its subsequent endothelial dysfunction have been reported to play a pivotal role in the initiation and progression of chronic vascular diseases. Inhibiting the attachment of monocytes to endothelium is a potential therapeutic strategy for vascular diseases treatment. α-Melanocyte stimulating hormone is generated from a precursor hormone called proopiomelanocortin by post-translational processing. However, whether α-melanocyte stimulating hormone plays a role in regulating endothelial inflammation is still unknown. In this study, the effects of α-melanocyte stimulating hormone on endothelial inflammation in human umbilical vein endothelial cell lines were investigated. And the result indicated that α-melanocyte stimulating hormone inhibits the expression of endothelial adhesion molecules, including vascular adhesion molecule-1 and E-selectin, thereby attenuating the adhesion of THP-1 cells to the surface of endothelial cells. Mechanistically, α-melanocyte stimulating hormone was found to inhibit NF-κB transcriptional activity. Finally, we found that the effect of α-melanocyte stimulating hormone on endothelial inflammation is dependent on its receptor melanocortin receptor 1. PMID:25898835

  8. Analysis of the effects of hydroquinone and arbutin on the differentiation of melanocytes.

    PubMed

    Inoue, Yu; Hasegawa, Seiji; Yamada, Takaaki; Date, Yasushi; Mizutani, Hiroshi; Nakata, Satoru; Matsunaga, Kayoko; Akamatsu, Hirohiko

    2013-01-01

    Hydroquinone (HQ) is a chemical compound that inhibits the functions of melanocytes and has long been known for its skin-whitening effect. According to previous studies, the Tyrosinase (Tyr) activity inhibitory effect and melanocyte-specific cell toxicity are known depigmenting mechanisms; however, details of the underlying mechanisms are unknown. Arbutin (Arb) is also known for its Tyr activity inhibitory effect and is commonly used as a skin-whitening agent. However, the detailed depigmenting mechanism of Arb is also not yet fully understood. Few studies have attempted to elucidate the effects of HQ and Arb on undifferentiated melanocytes. In this study, we examined the effects of HQ and Arb throughout each stage of differentiation of melanocytes using a mouse embryonic stem cell (ESC) culture system to induce melanocytes. The results showed that HQ in particular downregulated the early stage of differentiation, in which neural crest cells were generated, and the late stage of differentiation, in which melanogenesis became active. On the other hand, Arb had no effect on the differentiation of melanocytes, and only suppressed melanogenesis by specifically suppressing elevations in Tyr expression in the late stage of differentiation. PMID:24189417

  9. Effect of nicotine on melanogenesis and antioxidant status in HEMn-LP melanocytes

    SciTech Connect

    Delijewski, Marcin; Beberok, Artur; Otręba, Michał; Wrześniok, Dorota; Rok, Jakub; Buszman, Ewa

    2014-10-15

    Nicotine is a natural ingredient of tobacco plants and is responsible for the addictive properties of tobacco. Nowadays nicotine is also commonly used as a form of smoking cessation therapy. It is suggested that nicotine may be accumulated in human tissues containing melanin. This may in turn affect biochemical processes in human cells producing melanin. The aim of this study was to examine the effect of nicotine on melanogenesis and antioxidant status in cultured normal human melanocytes HEMn-LP. Nicotine induced concentration-dependent loss in melanocytes viability. The value of EC{sub 50} was determined to be 7.43 mM. Nicotine inhibited a melanization process in human light pigmented melanocytes and caused alterations of antioxidant defense system. Significant changes in cellular antioxidant enzymes: superoxide dismutase and catalase activities and in hydrogen peroxide content were stated. The obtained results may explain a potential influence of nicotine on biochemical processes in melanocytes in vivo during long term exposition to nicotine. - Graphical abstract: Nicotine inhibits melanogenesis and induces oxidative stress in HEMn-LP melanocytes. - Highlights: • Nicotine induces concentration-dependent loss in melanocytes viability. • Nicotine in non-cytotoxic concentrations inhibits melanogenesis. • Nicotine in higher concentrations induces oxidative stress.

  10. Recombinant Adeno-Associated Virus Serotype 6 Efficiently Transduces Primary Human Melanocytes

    PubMed Central

    Verdon, Daniel; Chen, Jennifer; Taylor, John A.; Dunbar, P. Rod

    2013-01-01

    The study of melanocyte biology is important to understand their role in health and disease. However, current methods of gene transfer into melanocytes are limited by safety or efficacy. Recombinant adeno-associated virus (rAAV) has been extensively investigated as a gene therapy vector, is safe and is associated with persistent transgene expression without genome integration. There are twelve serotypes and many capsid variants of rAAV. However, a comparative study to determine which rAAV is most efficient at transducing primary human melanocytes has not been conducted. We therefore sought to determine the optimum rAAV variant for use in the in vitro transduction of primary human melanocytes, which could also be informative to future in vivo studies. We have screened eight variants of rAAV for their ability to transduce primary human melanocytes and identified rAAV6 as the optimal serotype, transducing 7–78% of cells. No increase in transduction was seen with rAAV6 tyrosine capsid mutants. The number of cells expressing the transgene peaked at 6–12 days post-infection, and transduced cells were still detectable at day 28. Therefore rAAV6 should be considered as a non-integrating vector for the transduction of primary human melanocytes. PMID:23646140

  11. Oncogenic mutations in melanomas and benign melanocytic nevi of the female genital tract

    PubMed Central

    Tseng, Diane; Kim, Julie; Warrick, Andrea; Nelson, Dylan; Pukay, Marina; Beadling, Carol; Heinrich, Michael; Selim, Maria Angelica; Corless, Christopher L.; Nelson, Kelly

    2015-01-01

    Background The genetic heterogeneity of melanomas and melanocytic nevi of the female genital tract is poorly understood. Objective We aim to characterize the frequency of mutations of the following genes: BRAF, NRAS, KIT, GNA11, and GNAQ in female genital tract melanomas. We also characterize the frequency of BRAF mutations in female genital tract melanomas compared with melanocytic nevi. Methods Mutational screening was performed on the following female genital tract melanocytic neoplasms: 25 melanomas, 7 benign melanocytic nevi, and 4 atypical melanocytic nevi. Results Of the 25 female genital tract melanoma specimens queried, KIT mutations were detected in 4 (16.0%), NRAS mutations in 4 (16.0%), and BRAF mutations in 2 (8.0%) samples. Two of the tumors with KIT mutations harbored double mutations in the same exon. No GNAQ or GNA11 mutations were identified among 11 melanomas screened. BRAF V600E mutations were detected in 7 of 7 benign melanocytic genital nevi (100%) and 3 of 4 atypical genital nevi (75%). Limitations Our study is limited by the small sample size of this rare subset of melanomas. Conclusion KIT, NRAS, and BRAF mutations are found in a subset of female genital tract melanomas. Screening for oncogenic mutations is important for developing and applying clinical therapies for melanomas of the female genital tract. PMID:24842760

  12. Melanocytic Hyperplasia in the Epidermis Overlying Trichoblastomas in 100 Randomly Selected Cases.

    PubMed

    Al Omoush, Tahseen M M; Michal, Michael; Konstantinova, Anastasia M; Michal, Michal; Kutzner, Heinz; Kazakov, Dmitry V

    2016-04-01

    One hundred cases of trichoblastomas (large nodular, small nodular, cribriform, lymphadenoma, and columnar) were randomly selected and studied for the presence of melanocytic hyperplasia in the epidermis overlying the tumors, which was defined as foci of increased melanocytes in the basal layer of the epidermis (more than 1 per 4 basal keratinocytes). Focal melanocytic hyperplasia was detected in a total of 22 cases of trichoblastoma (22%), and this phenomenon was most frequently seen in columnar trichoblastoma (7 cases), followed by large nodular trichoblastoma (5 cases). The mechanism of epidermal melanocytic hyperplasia overlying trichoblastoma is unclear. Ultraviolet may be a contributing factor, as focal melanocytic hyperplasia was also detected in one-third of cases in the epidermis overlying uninvolved skin, usually associated with solar elastosis. This is further corroborated by the occurrence of the lesions predominantly on the face. Melanocytic hyperplasia overlying trichoblastoma appears to have no impact on the clinical appearance of the lesion and is recognized only microscopically. In an adequate biopsy specimen containing at least part of trichoblastoma, it should not cause any diagnostic problems. PMID:26885602

  13. Kyste hydatique du foie rompu dans la paroi abdominale et dans le muscle psoas : à propos d'une rare observation

    PubMed Central

    En-Nafaa, Issam; Moujahid, Mountassir; Alahyane, Abdelouahabe; Amil, Touria; Hanine, Ahmed; Ziadi, Tarik

    2011-01-01

    Le kyste hydatique du foie est une parasitose qui sévit à l′état endémique au maroc. La rupture dans la paroi abdominale et dans le psoas est une complication exceptionnelle. Nous rapportons un cas de kyste hydatique du foie rompu dans la paroi et dans le muscle psoas. Le diagnostic a été établi sur les données de l′échographie et surtout de la tomodensitométrie. Le patient a été opéré avec des suites simples. PMID:22187585

  14. Theorie de la Levitation Radiative a L'equilibre dans les Etoiles Naines Blanches Chaudes

    NASA Astrophysics Data System (ADS)

    Chayer, Pierre

    1995-01-01

    Les resultats de nouveaux calculs detailles de levitation radiative dans des naines blanches chaudes utilisant la base de donnees atomiques TOPBASE sont presentes. Des accelerations radiatives et des abondances d'equilibre ont ete calculees pour C, N, O, Ne, Na, Mg, Al, Si, S, Ar, Ca, et Fe, sur des grilles de modeles d'enveloppes stellaires riches en hydrogene et riches en helium. La grille des modeles de DA a des gravites telles que log g = 7.0, 7.5, 8.0, et 8.5, et couvre les temperatures effectives pour lesquelles 100,000K >= T_ {rm eff} >= 20,000K par sauts de 2,500K. La grille des modeles de DO/DB est similaire mais se prolonge a T_{rm eff } = 130,000K. Les resultats d'abondances d'equilibre de Ni dans des DA utilisant la base de donnees de Kurucz sont aussi presentes. Nous discutons dans les moindres details de la physique incluse dans les calculs afin de fournir une bonne comprehension physique de la levitation radiative sous les conditions rencontrees dans les naines blanches. Nous discutons aussi de la forme et de la dependance en fonction de la profondeur des reservoirs des elements, crees par un equilibre entre l'acceleration radiative et la gravite locale effective dans differentes enveloppes stellaires. Nous soulignons le role important joue dans la morphologie de ces reserviors par les etats d'ionisation dominants se trouvant dans la configuration gaz noble. Nos resultats centraux sont presentes sous forme de figures montrant le comportement de l'abondance photospherique estimee pour chaque element en fonction de la temperature effective et de la gravite de surface. Nous apportons egalement des ameliorations aux calculs de levitation radiative en utilisant une approche de modeles d'atmospheres pour les etoiles riches en hydrogene. Nous mettons l'emphase, en particulier, sur le role des traces d'elements lourds qui peuvent etre presents dans le plasma. Nous utilisons une table d'opacite monochromatique detaillee calculee pour un plasma compose de H

  15. Pigmented median raphe cyst of the penis with consideration of the possible mechanism of melanocytic colonization: A case report.

    PubMed

    Ishida, Mitsuaki; Iwai, Muneo; Yoshida, Keiko; Kagotani, Akiko; Okabe, Hidetoshi

    2014-02-01

    Median raphe cyst is a rare lesion located on the median raphe. The cyst wall is lined by cuboidal to columnar cells, transitional (urothelial) cells, stratified squamous cells or a mixture of these. The normal urethral mucosa and the median raphe cyst usually lack melanocytes and/or melanin pigment. However, albeit extremely rare, the presence of melanin pigment and/or melanocytes in median raphe cyst, namely pigmented median raphe cyst, has been previously reported. The current case report presents the sixth case of pigmented median raphe cyst and discusses the possible mechanism of melanocytic colonization in this tumor. A 48-year-old male presented with a nodule on the ventral surface of the penis. Histopathological study revealed that the cyst wall was covered by uniform bland cuboidal to urothelial cells. The peculiar observation was the presence of dendritic melanocytes among the epithelial cells. Therefore, a diagnosis of pigmented median raphe cyst was determined. Immunohistochemically, stem cell factor and endothelin-1 were not expressed in the epithelial cells of the cyst wall. It is well-known that melanocytes are rarely found in various non-melanocytic tumors, a phenomenon termed 'colonization'. The mechanism by which melanocytes appear in median raphe cyst remains unclear. The present report is the first to demonstrate that melanocytic proliferation and differentiation factors, such as stem cell factor and endothelin-1, are not involved in the pigmentation of median raphe cyst. In addition, aberrant melanocytic migration may contribute to the development of this type of lesion. PMID:24396444

  16. Functional melanocytes are readily reprogrammable from multilineage-differentiating stress-enduring (muse) cells, distinct stem cells in human fibroblasts.

    PubMed

    Tsuchiyama, Kenichiro; Wakao, Shohei; Kuroda, Yasumasa; Ogura, Fumitaka; Nojima, Makoto; Sawaya, Natsue; Yamasaki, Kenshi; Aiba, Setsuya; Dezawa, Mari

    2013-10-01

    The induction of melanocytes from easily accessible stem cells has attracted attention for the treatment of melanocyte dysfunctions. We found that multilineage-differentiating stress-enduring (Muse) cells, a distinct stem cell type among human dermal fibroblasts, can be readily reprogrammed into functional melanocytes, whereas the remainder of the fibroblasts do not contribute to melanocyte differentiation. Muse cells can be isolated as cells positive for stage-specific embryonic antigen-3, a marker for undifferentiated human embryonic stem cells, and differentiate into cells representative of all three germ layers from a single cell, while also being nontumorigenic. The use of certain combinations of factors induces Muse cells to express melanocyte markers such as tyrosinase and microphthalmia-associated transcription factor and to show positivity for the 3,4-dihydroxy-L-phenylalanine reaction. When Muse cell-derived melanocytes were incorporated into three-dimensional (3D) cultured skin models, they localized themselves in the basal layer of the epidermis and produced melanin in the same manner as authentic melanocytes. They also maintained their melanin production even after the 3D cultured skin was transplanted to immunodeficient mice. This technique may be applicable to the efficient production of melanocytes from accessible human fibroblasts by using Muse cells, thereby contributing to autologous transplantation for melanocyte dysfunctions, such as vitiligo. PMID:23563197

  17. Hans Bethe : Des etoiles a la bombe

    NASA Astrophysics Data System (ADS)

    Bonnet-Bidaud, J. M.

    1996-06-01

    Il comprit le premier comment brillent les etoiles. Il fut aussi de cette poignee de scientifiques qui, dans le secret de Los Alamos, mirent au point la tristement celebre bombe atomique. Hans Bethe est l'un des derniers geants qui auront marque la physique de ce siecle d'une empreinte indelebile. C'est dans le bureau 01 du prestigieux laboratoire Kellog de l'institut Caltech qu'il a bien voulu retracer pour nous son impressionnante carriere, et revenir sur les motivations qui ont guide ses pas.

  18. De l'importance des orbites periodiques: Detection et applications

    NASA Astrophysics Data System (ADS)

    Doyon, Bernard

    L'ensemble des Orbites Periodiques Instables (OPIs) d'un systeme chaotique est intimement relie a ses proprietes dynamiques. A partir de l'ensemble (en principe infini) d'OPIs cachees dans l'espace des phases, on peut obtenir des quantites dynamiques importantes telles les exposants de Lyapunov, la mesure invariante, l'entropie topologique et la dimension fractale. En chaos quantique (i.e. l'etude de systemes quantiques qui ont un equivalent chaotique dans la limite classique), ces memes OPIs permettent de faire le pont entre le comportement classique et quantique de systemes non-integrables. La localisation de ces cycles fondamentaux est un probleme complexe. Cette these aborde dans un premier temps le probleme de la detection des OPIs dans les systemes chaotiques. Une etude comparative de deux algorithmes recents est presentee. Nous approfondissons ces deux methodes afin de les utiliser sur differents systemes dont des flots continus dissipatifs et conservatifs. Une analyse du taux de convergence des algorithmes est aussi realisee afin de degager les forces et les limites de ces schemes numeriques. Les methodes de detection que nous utilisons reposent sur une transformation particuliere de la dynamique initiale. Cette astuce nous a inspire une methode alternative pour cibler et stabiliser une orbite periodique quelconque dans un systeme chaotique. Le ciblage est en general combine aux methodes de controle pour stabiliser rapidement un cycle donne. En general, il faut connaitre la position et la stabilite du cycle en question. La nouvelle methode de ciblage que nous presentons ne demande pas de connaitre a priori la position et la stabilite des orbites periodiques. Elle pourrait etre un outil complementaire aux methodes de ciblage et de controle actuelles.

  19. A multimodal assessment of melanin and melanocyte activity in abnormally pigmented hypertrophic scar.

    PubMed

    Travis, Taryn E; Ghassemi, Pejhman; Ramella-Roman, Jessica C; Prindeze, Nicholas J; Paul, Dereck W; Moffatt, Lauren T; Jordan, Marion H; Shupp, Jeffrey W

    2015-01-01

    Using a validated swine model of human scar formation, hyperpigmented and hypopigmented scar samples were examined for their histological and optical properties to help elucidate the mechanisms and characteristics of dyspigmentation. Full-thickness wounds were created on the flanks of red Duroc pigs and allowed to heal. Biopsies from areas of hyperpigmentation, hypopigmentation, and uninjured tissue were fixed and embedded for histological examination using Azure B and primary antibodies to S100B, HMB45, and α-melanocyte-stimulating hormone (α-MSH). Spatial frequency domain imaging (SFDI) was then used to examine the optical properties of scars. Hyperpigmentation was first noticeable in healing wounds around weeks 2 to 3, gradually becoming darker. There was no significant difference in S100B staining for the presence of melanocytes between hyperpigmented and hypopigmented scar samples. Azure B staining of melanin was significantly greater in histological sections from hyperpigmented areas than in sections from both uninjured skin and hypopigmented scar (P < .0001). There was significantly greater staining for α-MSH in hyperpigmented samples compared with hypopigmented samples (P = .0121), and HMB45 staining was positive for melanocytes in hyperpigmented scar. SFDI at a wavelength of 632 nm resulted in an absorption coefficient map correlating with visibly hyperpigmented areas of scars. In a red Duroc model of hypertrophic scar formation, melanocyte number is similar in hyperpigmented and hypopigmented tissues. Hyperpigmented tissues, however, show a greater amount of melanin and α-MSH, along with immunohistochemical evidence of stimulated melanocytes. These observations encourage further investigation of melanocyte stimulation and the inflammatory environment within a wound that may influence melanocyte activity. Additionally, SFDI can be used to identify areas of melanin content in mature, pigmented scars, which may lead to its usefulness in wounds at earlier

  20. High-definition optical coherence tomography of melanocytic skin lesions.

    PubMed

    Gambichler, Thilo; Plura, Iris; Schmid-Wendtner, Monika; Valavanis, Konstantinos; Kulichova, Daniela; Stücker, Markus; Pljakic, Azem; Berking, Carola; Maier, Tanja

    2015-08-01

    High-definition optical coherence tomography (HD-OCT) scanners have recently been developed. We assessed micromorphological HD-OCT correlates of benign naevi (BN) and malignant melanoma (MM). 28 BN and 20 MM were studied using HD-OCT and histology. Epidermal honeycomb/cobblestone pattern, regular junctional cell nests, and edged papillae are more often observed in BN, whereas fusion of rete ridges, pagetoid cells and junctional and/or dermal nests with atypical cells are more frequently seen in MM. A high overlap of HD-OCT features in BN and MM was observed and in 20% of MM we did not find evidence for malignancy in OCT images at all. Using HD-OCT it is possible to visualize architectural and cellular alterations of melanocytic skin lesions. The overlap of HD-OCT features seen in BN and MM and the absence of suspicious HD-OCT features in some MM represents an important limitation of HD-OCT affecting the sensitivity of HD-OCT in diagnosing MM. High-definition optical coherence tomography and the corresponding vertically sectioned histology of a compound naevus. PMID:25237005

  1. Dedifferentiation of human epidermal melanocytes into melanoblasts in vitro.

    PubMed

    Zhao, Zhiguo; Jin, Cheng; Ding, Keyun; Ge, Xiaopeng; Dai, Lllan

    2012-07-01

    Melanoblasts (MB) are also called melanocyte (MC) precursor cells. In recent years, people have successfully cultivated human and mouse MB. Previous studies have shown that EDN3 induces cultivated bird MC to re-differentiate into double potential progenitor cells of MB. However, no study has reported whether in vitro cultivated human MC can be dedifferentiated. Our research on MC that were purified and cultivated in vitro found that adding 10 nm endothelin 1 (EDN1) (ET-1) to the MC medium without phorbol 12-myristate 13-acetate (PMA) induced a few MC to dedifferentiate and become a new type of cell. This new cell type was separated, purified, cloned and identified using multiple approaches. The results show that 88.7%, 8.69% and 2.5% of this new cell type were cells in the G(0) -G(1) , G(2) -M and S stages, respectively. The new cell type did not exhibit an apparent apoptotic peak, and its apoptotic rate was 0.09%. Stage I melanosomes were observed in the cytoplasm and were negative for the DOPA reaction. The cell surface antigen expression was positive for tyrosinase-related protein 2, negative or positive for c-kit and negative for S-100 and HMB45, showing that these cells were dedifferentiated MB of MC. Our findings provided evidence for atavism of mature human MC under certain conditions. PMID:22540983

  2. Treatment of a giant congenital melanocytic nevus in the adult: review of the current management of giant congenital melanocytic nevus.

    PubMed

    Su, Jeannie J; Chang, Daniel K; Mailey, Brian; Gosman, Amanda

    2015-05-01

    Giant congenital melanocytic nevi (GCMNs) create cosmetic disfigurements and pose risk for malignant transformation. Adult GCMN cases are uncommon because most families opt for surgical treatment during childhood. We review the current literature on GCMN and present an interesting case of an adult with a GCMN encompassing the entire back with painful nodules exhibiting gross involvement of his back musculature, without pathologic evidence of malignancy. Surgical management was deferred in childhood because of parental desires to allow the patient to make his own decision, and treatment in adulthood was pursued on the basis of the significant impairment of the patient's quality of life and self-esteem due to the massive size and deforming nature of the nevus. The treatment strategy used for this young adult male patient involved a massive en bloc excision of the GCMN with partial resection of the latissimus dorsi, followed by a 5-week staged reconstructive process using dermal regenerative matrices and split-thickness skin grafting. Because of the shift in GCMN management from early surgical management to more conservative management, we may see an increase in adult cases of GCMN. Thus, it is critical to better understand the controversy surrounding early versus delayed management of GCMN. PMID:25664413

  3. Oxidative stress-induced overexpression of miR-25: the mechanism underlying the degeneration of melanocytes in vitiligo.

    PubMed

    Shi, Q; Zhang, W; Guo, S; Jian, Z; Li, S; Li, K; Ge, R; Dai, W; Wang, G; Gao, T; Li, C

    2016-03-01

    Oxidative stress has a critical role in the pathogenesis of vitiligo. However, the specific molecular mechanism involved in oxidative stress-induced melanocyte death is not well characterized. Given the powerful role of microRNAs (miRNAs) in the regulation of cell survival as well as the fact that the generation of miRNAs can be affected by oxidative stress, we hypothesized that miRNAs may participate in vitiligo pathogenesis by modulating the expression of vital genes in melanocytes. In the present study, we initially found that miR-25 was increased in both serum and lesion samples from vitiligo patients, and its serum level was correlated with the activity of vitiligo. Moreover, restoration of miR-25 promoted the H2O2-induced melanocyte destruction and led to the dysfunction of melanocytes. Further experiments proved that MITF, a master regulator in melanocyte survival and function, accounted for the miR-25-caused damaging impact on melanocytes. Notably, other than the direct role on melanocytes, we observed that miR-25 inhibited the production and secretion of SCF and bFGF from keratinocytes, thus impairing their paracrine protective effect on the survival of melanocytes under oxidative stress. At last, we verified that oxidative stress could induce the overexpression of miR-25 in both melanocytes and keratinocytes possibly by demethylating the promoter region of miR-25. Taken together, our study demonstrates that oxidative stress-induced overexpression of miR-25 in vitiligo has a crucial role in promoting the degeneration of melanocytes by not only suppressing MITF in melanocytes but also impairing the paracrine protective effect of keratinocytes. Therefore, it is worthy to investigate the possibility of miR-25 as a potential drug target for anti-oxidative therapy in vitiligo. PMID:26315342

  4. Extracellular vesicles are transferred from melanocytes to keratinocytes after UVA irradiation

    PubMed Central

    Wäster, Petra; Eriksson, Ida; Vainikka, Linda; Rosdahl, Inger; Öllinger, Karin

    2016-01-01

    Ultraviolet (UV) irradiation induces skin pigmentation, which relies on the intercellular crosstalk of melanin between melanocytes to keratinocytes. However, studying the separate effects of UVA and UVB irradiation reveals differences in cellular response. Herein, we show an immediate shedding of extracellular vesicles (EVs) from the plasma membrane when exposing human melanocytes to UVA, but not UVB. The EV-shedding is preceded by UVA-induced plasma membrane damage, which is rapidly repaired by Ca2+-dependent lysosomal exocytosis. Using co-cultures of melanocytes and keratinocytes, we show that EVs are preferably endocytosed by keratinocytes. Importantly, EV-formation is prevented by the inhibition of exocytosis and increased lysosomal pH but is not affected by actin and microtubule inhibitors. Melanosome transfer from melanocytes to keratinocytes is equally stimulated by UVA and UVB and depends on a functional cytoskeleton. In conclusion, we show a novel cell response after UVA irradiation, resulting in transfer of lysosome-derived EVs from melanocytes to keratinocytes. PMID:27293048

  5. Hyperoside protects human primary melanocytes against H2O2-induced oxidative damage

    PubMed Central

    YANG, BIN; YANG, QIN; YANG, XIN; YAN, HONG-BO; LU, QI-PING

    2016-01-01

    Cuscutae semen has been shown to have beneficial effects in the treatment of vitiligo, recorded in the Chinese Pharmacopoeia, whereas the effects of its constituent compounds remains to be elucidated. Using a tetrazolium bromide assay, the present study found that hyperoside (0.5–200 µg/ml) significantly increased the viability of human melanocytes in a time- and dose-dependent manner. The present study used a cell model of hydrogen peroxide (H2O2)-induced oxidative damage to examine the effect of hyperoside on human primary melanocytes. The results demonstrated that hyperoside pretreatment for 2 h decreased cell apoptosis from 54.03±9.11 to 17.46±3.10% in the H2O2-injured melanocytes. The levels of oxidative stress in the mitochondrial membrane potential of the melanocytes increased following hyperoside pretreatment. The mRNA and protein levels of B-cell lymphoma-2/Bcl-2-associated X protein and caspase 3 were regulated by hyperoside, and phosphoinositide 3-kinase/AKT and mitogen-activated protein kinase signaling were also mediated by hyperoside. In conclusion, the results of the present study demonstrated that hyperoside protected the human primary melanocytes against oxidative damage. PMID:27082158

  6. Heme oxygenase-1 expression protects melanocytes from stress-induced cell death: implications for vitiligo

    PubMed Central

    Elassiuty, Yasser E.; Klarquist, Jared; Speiser, Jodi; Yousef, Randa M.; EL Refaee, Abdelaziz A.; Hunter, Nahla S.; Shaker, Olfat G.; Gundeti, Mohan; Nieuweboer-Krobotova, Ludmila; Le Poole, I. Caroline

    2013-01-01

    To study protection of melanocytes from stress-induced cell death by heme oxygenases during depigmentation and repigmentation in vitiligo, expression of isoforms 1 and 2 was studied in cultured control and patient melanocytes and normal skin explants exposed to UV or bleaching agent 4-TBP. Similarly, expression of heme oxygenases was followed in skin from vitiligo patients before and after PUVA treatment. Single and double immunostainings were used in combination with light and confocal microscopic analysis and Western blotting. Melanocyte expression of heme oxygenase 1 is upregulated, whereas heme oxygenase 2 is reduced in response to UV and 4-TBP. Upregulation of inducible heme oxygenase 1 was also observed in UV-treated explant cultures, in skin of successfully PUVA-treated patients and in melanocytes cultured from vitiligo non-lesional skin. Heme oxygenase encoding genes were subsequently cloned to study consequences of either gene product on cell viability, demonstrating that HO-1 but not HO-2 overexpression offers protection from stress-induced cell death in MTT assays. HO-1 expression by melanocytes may contribute to beneficial effects of UV treatment for vitiligo patients. PMID:21426408

  7. Lineage-specific transcriptional regulation of DICER by MITF in melanocytes.

    PubMed

    Levy, Carmit; Khaled, Mehdi; Robinson, Kathleen C; Veguilla, Rosa A; Chen, Po-Hao; Yokoyama, Satoru; Makino, Eiichi; Lu, Jun; Larue, Lionel; Beermann, Friedrich; Chin, Lynda; Bosenberg, Marcus; Song, Jun S; Fisher, David E

    2010-06-11

    DICER is a central regulator of microRNA maturation. However, little is known about mechanisms regulating its expression in development or disease. While profiling miRNA expression in differentiating melanocytes, two populations were observed: some upregulated at the pre-miRNA stage, and others upregulated as mature miRNAs (with stable pre-miRNA levels). Conversion of pre-miRNAs to fully processed miRNAs appeared to be dependent upon stimulation of DICER expression--an event found to occur via direct transcriptional targeting of DICER by the melanocyte master transcriptional regulator MITF. MITF binds and activates a conserved regulatory element upstream of DICER's transcriptional start site upon melanocyte differentiation. Targeted KO of DICER is lethal to melanocytes, at least partly via DICER-dependent processing of the pre-miRNA-17 approximately 92 cluster thus targeting BIM, a known proapoptotic regulator of melanocyte survival. These observations highlight a central mechanism underlying lineage-specific miRNA regulation which could exist for other cell types during development. PMID:20550935

  8. Ex vivo reconstruction of the epidermis with melanocytes and the influence of UVB.

    PubMed

    Bessou, S; Surlève-Bazeille, J E; Sorbier, E; Taïeb, A

    1995-10-01

    To study pigmentation, we have reconstructed an epidermis ex vivo with keratinocytes and melanocytes. Keratinocytes and melanocytes were grown first in primary cocultures and separately in secondary cultures, then seeded on a dead deepidermized dermis (Pruniéras type) at a 1:20 melanocyte/keratinocyte ratio. Reconstructed epidermis were grown in a special medium enriched with calcium and fetal bovine serum lifted for 15 days at the air-liquid interface. Using histology, immunohistochemistry and electron microscopy we have shown an excellent level of differentiation of the reconstructed epidermis and a physiologic distribution of dendritic melanocytes in the basal layer capable of melanosome transfer to keratinocytes. UVB irradiation 0.15 J/cm2 x 5 consecutive days increased melanocyte numbers and stimulated pigmentation as evidenced macroscopically and microscopically and at the biochemical level. Following UVB irradiation melanosome transfer was markedly increased and isolated or clumps of melanosomes were seen in the basal layers as well as in the stratum corneum. This model allows the study of the physiology of pigmentation ex vivo. PMID:8789198

  9. Functional Characterization of the Odorant Receptor 51E2 in Human Melanocytes.

    PubMed

    Gelis, Lian; Jovancevic, Nikolina; Veitinger, Sophie; Mandal, Bhubaneswar; Arndt, Hans-Dieter; Neuhaus, Eva M; Hatt, Hanns

    2016-08-19

    Olfactory receptors, which belong to the family of G-protein-coupled receptors, are found to be ectopically expressed in non-sensory tissues mediating a variety of cellular functions. In this study we detected the olfactory receptor OR51E2 at the transcript and the protein level in human epidermal melanocytes. Stimulation of primary melanocytes with the OR51E2 ligand β-ionone significantly inhibited melanocyte proliferation. Our results further showed that β-ionone stimulates melanogenesis and dendritogenesis. Using RNA silencing and receptor antagonists, we demonstrated that OR51E2 activation elevated cytosolic Ca(2+) and cAMP, which could mediate the observed increase in melanin synthesis. Co-immunocytochemical stainings using a specific OR51E2 antibody revealed subcellular localization of the receptor in early endosomes associated with EEA-1 (early endosome antigen 1). Plasma membrane preparations showed that OR51E2 protein is present at the melanocyte cell surface. Our findings thus suggest that activation of olfactory receptor signaling by external compounds can influence melanocyte homeostasis. PMID:27226631

  10. Testosterone and UVL-B stimulation of epidermal melanocytes in rat scrotal skin.

    PubMed

    Glimcher, M D; Wilson, M J; Szabo, G

    1979-01-01

    The effects of UVL-B and/or testosterone replacemnt therapy are compared in normal and castrated rats in order to determine whether testosterone is required for UVL-B (290-315 nm) stimulation of melanogenesis in the testosterone-dependent epidermal melanocyte system of the scrotal skin of black Long Evans rats. Testosterone is not a prerequisite for UVL-B stimulation of melanocytes as in both castrates and normal animals the melanocytes respond to UVL-B by increases in size, length and number of dendrites (dendriticness), and tyrosinase activity (intensity of Dopa reaction). Addition of testosterone to castrates does enhance the effects of UVL-B. However, UVL-B with or without testosterone cannot maintain normal melanogenesis in rats irradiated immediately after castration nor can it restore normal melanogenesis following long term castration. Bth the amount of UVL nergy/exposure and the number of exposures are important variables in stimulation of the epidermal melanocytes. Administration of a dose of UVL-B to castrates in a single exposure is ineffective, while the same overall dose spread over several exposures increases the size and dendriticness of melanocytes. Testosterone and UVL-B act synergistically in affecting melanogenesis although neither singly nor in combination are they able to fully restore normal melanogenesis. PMID:760595

  11. Melanocytes and keratinocytes have distinct and shared responses to ultraviolet radiation and arsenic.

    PubMed

    Cooper, K L; Yager, J W; Hudson, L G

    2014-01-30

    The rise of melanoma incidence in the United States is a growing public health concern. A limited number of epidemiology studies suggest an association between arsenic levels and melanoma risk. Arsenic acts as a co-carcinogen with ultraviolet radiation (UVR) for the development of squamous cell carcinoma and proposed mechanisms include generation of oxidative stress by arsenic and UVR and inhibition of UVR-induced DNA repair by arsenic. In this study, we investigate similarities and differences in response to arsenic and UVR in keratinocytes and melanocytes. Normal melanocytes are markedly more resistant to UVR-induced cytotoxicity than normal keratinocytes, but both cell types are equally sensitive to arsenite. Melanocytes were more resistant to arsenite and UVR stimulation of superoxide production than keratinocytes, but the concentration of arsenite necessary to inhibit the activity of the DNA repair protein poly(ADP-ribose)polymerase and enhance retention of UVR-induced DNA damage was essentially equivalent in both cell types. These findings suggest that although melanocytes are less sensitive than keratinocytes to initial UVR-mediated DNA damage, both of these important target cells in the skin share a mechanism related to arsenic inhibition of DNA repair. These findings suggest that concurrent chronic arsenic exposure could promote retention of unrepaired DNA damage in melanocytes and act as a co-carcinogen in melanoma. PMID:24270004

  12. Extracellular vesicles are transferred from melanocytes to keratinocytes after UVA irradiation.

    PubMed

    Wäster, Petra; Eriksson, Ida; Vainikka, Linda; Rosdahl, Inger; Öllinger, Karin

    2016-01-01

    Ultraviolet (UV) irradiation induces skin pigmentation, which relies on the intercellular crosstalk of melanin between melanocytes to keratinocytes. However, studying the separate effects of UVA and UVB irradiation reveals differences in cellular response. Herein, we show an immediate shedding of extracellular vesicles (EVs) from the plasma membrane when exposing human melanocytes to UVA, but not UVB. The EV-shedding is preceded by UVA-induced plasma membrane damage, which is rapidly repaired by Ca(2+)-dependent lysosomal exocytosis. Using co-cultures of melanocytes and keratinocytes, we show that EVs are preferably endocytosed by keratinocytes. Importantly, EV-formation is prevented by the inhibition of exocytosis and increased lysosomal pH but is not affected by actin and microtubule inhibitors. Melanosome transfer from melanocytes to keratinocytes is equally stimulated by UVA and UVB and depends on a functional cytoskeleton. In conclusion, we show a novel cell response after UVA irradiation, resulting in transfer of lysosome-derived EVs from melanocytes to keratinocytes. PMID:27293048

  13. Immune-phenotypical markers for the differential diagnosis of melanocytic lesions

    PubMed Central

    Botti, Gerardo; Marra, Laura; Anniciello, Annamaria; Scognamiglio, Giosuè; Gigantino, Vincenzo; Cantile, Monica

    2015-01-01

    For specific subsets of melanocytic proliferations, there are morphologic limitations in the histological diagnosis, especially for borderline melanocytic tumors. In particular, Spitzoid proliferations can be difficult to diagnose. For these reasons, in the last years, clinic research has focusedattention on discovery of new diagnostic markers. Published gene expression and proteomic profiling data indicate new candidate molecules involved in melanoma pathogenesis, and useful in differential diagnosis of difficult melanocytic lesions. Recently, the diagnostic power of galectin-3 was demonstrated in series of melanocytic lesions, with a strong increasing of expression in malignant lesions compared with benign lesions. Similarly, the accumulation of Collagen XVII antibody was detected in vertical melanoma fronts and associated with invasive phenotype. Moreover, overexpression of cyclin D1 and p21 was detected in Spitz nevi compared with non-spitzoid melanomas; Ki-67 appears highly expressed in deep areas of non-spitzoid melanomas. In this review,werealizedan overviewofthe main molecular markersthat canbe a usefultoolfor the differential diagnosisofbenign, borderlineand malignant melanocytic lesions, related to their biological behavior, useful also for predicting the evolutionof the disease. PMID:26617684

  14. Dissolution de la matiere lignocellulosique dans les liquides ioniques

    NASA Astrophysics Data System (ADS)

    Rebiere, Jeremy

    De nos jours, avec la raréfaction des ressources fossiles, le développement de procédés entrant dans le cadre de la chimie verte s'accentue. De plus, ces procédés utilisent comme ressources, des matériaux d'origine végétale, abondants et biodégradables. Au cours de ces 20 dernières années, la littérature utilisant les liquides ioniques (LI) connait une importante croissance. Ces solvants sont de plus en plus employés dans des réactions chimiques classiques. Cependant le coût de leur synthèse en fait un solvant réactionnel cher dont l'application en tant que tel dans l'industrie ne peut être raisonnablement envisagée. Ces liquides ioniques permettent la dissolution des matériaux lignocellulosiques (lignine ou cellulose) et possèdent des propriétés physico-chimiques intéressantes. Nous savons également que la dissolution de la cellulose par des procédés d'hydrolyse classique s'effectue dans des conditions dures, dues à la structure cristalline de la cellulose, (fortes concentrations en acide) qui paraissent limitées pour une utilisation à grande échelle. Il est donc nécessaire de rechercher des méthodes moins onéreuses et plus efficaces écologiquement. S'appuyant sur des recherches démontrant que la dissolution de la cellulose dans les LI, diminue la cristallinité de la cellulose, nous allons chercher à démontrer au cours de ces travaux, la possibilité d'utiliser les LI comme moyen de prétraitement pour la dissolution de la cellulose. Nous allons nous attacher à dissoudre la cellulose, et à étudier les proportions pouvant être dissoutes. Puis nous chercherons à récupérer puis à réutiliser ces LI. Enfin nous cherchons à caractériser les modifications apportées à notre cellulose. Mots Clés liquide ionique, cellulose, cristallinité, réactivité, dissolution, régénération, non-solvant, purification, prétraitement, zone amorphe.

  15. Partager : des technologies de pointe au service de la société

    ScienceCinema

    None

    2011-10-06

    Médecine, climatologie, métrologie et informatique, les techniques utilisées par le LHC trouvent déjà des répercussions dans d?autres domaines scientifiques. Utilisant des techniques inédites, la physique des particules en fait bénéficier la société toute entière.

  16. Les effets des interfaces sur les proprietes magnetiques et de transport des multicouches nickel/iron et cobalt/silver

    NASA Astrophysics Data System (ADS)

    Veres, Teodor

    Cette these est consacree a l'etude de l'evolution structurale des proprietes magnetiques et de transport des multicouches Ni/Fe et nanostructures a base de Co et de l'Ag. Dans une premiere partie, essentiellement bibliographique, nous introduisons quelques concepts de base relies aux proprietes magnetiques et de transport des multicouches metalliques. Ensuite, nous presentons une breve description des methodes d'analyse des resultats. La deuxieme partie est consacree a l'etude des proprietes magnetiques et de transport des multicouches ferromagnetiques/ferromagnetiques Ni/Fe. Nous montrerons qu'une interpretation coherente de ces proprietes necessite la prise en consideration des effets des interfaces. Nous nous attacherons a mettre en evidence, a evaluer et a etudier les effets de ces interfaces ainsi que leur evolution, et ce, suite a des traitements thermiques tel que le depot a temperature elevee et l'irradiation ionique. Les analyses correlees de la structure et de la magnetoresistance nous permettront d'emettre des conclusions sur l'influence des couches tampons entre l'interface et le substrat ainsi qu'entre les couches elles-memes sur le comportement magnetique des couches F/F. La troisieme partie est consacree aux systemes a Magneto-Resistance Geante (MRG) a base de Co et Ag. Nous allons etudier l'evolution de la microstructure suite a l'irradiation avec des ions Si+ ayant une energie de 1 MeV, ainsi que les effets de ces changements sur le comportement magnetique. Cette partie debutera par l'analyse des proprietes d'une multicouche hybride, intermediaire entre les multicouches et les materiaux granulaires. Nous analyserons a l'aide des mesures de diffraction, de relaxation superparamagnetique et de magnetoresistance, les evolutions structurales produites par l'irradiation ionique. Nous etablirons des modeles qui nous aideront a interpreter les resultats pour une serie des multicouches qui couvrent un large eventail de differents comportements magnetiques

  17. Organ culture of mammalian skin and the effects of ultraviolet light and testosterone on melanocyte morphology and function.

    PubMed

    Glimcher, M E; Garcia, R I; Szabó, G

    1978-05-01

    Scrotal skin of black Long-Evans rats and human thigh skin were maintained in vitro as organ cultures for as long as 14 days, and examined histologically using the combined skin splitting and Dopa techniques. Selected rat skin cultures received testosterone in the culture medium and/or were irradiated with ultraviolet light (290-320 nm UVL). With increased time in culture, scrotal melanocytes round up and there is an increase in epidermal pigmentation. Human skin behaves similarly; after eight days in vitro human melanocytes also become rounded, but remain strongly Dopa-positive. Addition of exogenous testosterone to cultured rat skin maintains dendritic morphology of melanocytes, but cell body size is still reduced. UVL irradiation stimulates melanocytes in rat skin cultures, maintaining their dendritic morphology and increasing epidermal and dermal pigmentation. Cultured skin receiving both UVL and testosterone illustrates a synergistic effect. Electron microscopic examination of cultured rat skin shows the presence of large melanosome complexes in keratinocytes, much larger than those found in vivo. Melanocytes appear to be active as they contain an extensive Golgi zone, rough endoplasmic reticulum, and melanosomes in various stages of formation. Dermis contained many dermal melanocytes and macrophages laden with melanosomes, correlating with the increased visible dermal pigmentation in vitro. This UVL stimulation of melanocytes in our skin organ cultures contrasts with the lack of melanogenic stimulation found in melanoma cell cultures. Our findings suggest that the intact epidermal melanin unit may be necessary for UVL stimulation of melanocytes. PMID:641488

  18. A deep penetrating facial congenital melanocytic tumor with bone involvement and ipsilateral eye blindness.

    PubMed

    Bergman, Reuven; Ben-Arush, Miriam W; Bar-Shalom, Rachel; Gilboa, Michael; Simon, Einav; Hershkovitz, Dov; Sabo, Edmond; Maly, Alexander; Gerami, Pedram; Goldsher, Dorith

    2015-01-01

    Bone involvement has been described in tumors with melanocytic differentiation such as melanotic neuroectodermal tumor of infancy, and very rarely in cellular blue nevi and neurocristic cutaneous hamartoma. We present an unusual case of facial congenital melanocytic tumor that involved the underlying bones and maxillary sinus and led to unilateral blindness. A newborn with a large red bluish patch with peripheral brown and black macules overlying marked swelling on the left side of his face was presented. The tumor was shown by magnetic resonance imaging, scintigraphy, and histopathology to invade the underlying bones and maxillary sinus and to compress the left eyeball resulting in blindness. Histopathology, immunohistochemistry, morphometric computerized microscopy, molecular genetic mutation analysis, and fluorescent in situ hybridization studies were more congruent with a melanocytic nevus. An 8.5-year follow-up was uneventful, with spontaneous partial shrinkage of the tumor. PMID:25222197

  19. [Management of benign melanocytic lesions as a melanoma prevention. Systematic review].

    PubMed

    Linertová, Renata; Valcárcel-Nazco, Cristina; Lacalle-Remigio, Juan Ramón

    2016-08-19

    There is a growing concern and awareness of skin cancer. As a result, possibly unnecessary surgeries of melanocytic lesions are carried out as a prophylactic measure. We performed a systematic review of the medical literature to identify primary studies on the effectiveness and cost-effectiveness of surgery treatment of benign melanocytic lesions for melanoma prevention. We included 19 primary studies on surgical treatment of acquired melanocytic lesions and one economic evaluation. Indicators, such as number needed to treat and the malignancy ratio, depend on several factors such as specialty and experience of the physician, pressure from the patient or patient characteristics. Early diagnosis of melanoma is critical in preventing skin cancer. However, primary studies show through several indicators that there are factors that increase the proportion of lesions treated unnecessarily. Effectiveness can be improved by careful use of techniques to identify suspicious lesions and educational programs for physicians, especially in primary care. PMID:27026061

  20. Topology of feather melanocyte progenitor niche allows complex pigment patterns to emerge.

    PubMed

    Lin, S J; Foley, J; Jiang, T X; Yeh, C Y; Wu, P; Foley, A; Yen, C M; Huang, Y C; Cheng, H C; Chen, C F; Reeder, B; Jee, S H; Widelitz, R B; Chuong, C M

    2013-06-21

    Color patterns of bird plumage affect animal behavior and speciation. Diverse patterns are present in different species and within the individual. Here, we study the cellular and molecular basis of feather pigment pattern formation. Melanocyte progenitors are distributed as a horizontal ring in the proximal follicle, sending melanocytes vertically up into the epithelial cylinder, which gradually emerges as feathers grow. Different pigment patterns form by modulating the presence, arrangement, or differentiation of melanocytes. A layer of peripheral pulp further regulates pigmentation via patterned agouti expression. Lifetime feather cyclic regeneration resets pigment patterns for physiological needs. Thus, the evolution of stem cell niche topology allows complex pigment patterning through combinatorial co-option of simple regulatory mechanisms. PMID:23618762

  1. BAP1 and BRAFV600E expression in benign and malignant melanocytic proliferations.

    PubMed

    Piris, Adriano; Mihm, Martin C; Hoang, Mai P

    2015-02-01

    BAP1 (BRCA1-associated protein 1) is a tumor suppressor gene whose mutations have recently been reported to increase susceptibility for the development of uveal melanoma, cutaneous atypical and epithelioid melanocytic lesions, clear cell renal cell carcinoma, and other tumors. Screening for BAP1 mutation/loss/inactivation and BRAFV600E mutation can be done by immunohistochemistry. We investigated BAP1 and BRAFV600E expression in 193 sporadic melanocytic lesions (11 dermal nevi, 20 congenital nevi, 40 primary and nondesmoplastic melanomas, 40 desmoplastic melanomas, 23 metastatic melanomas, 17 Spitz nevi, 19 atypical Spitz nevi, 8 atypical Spitz tumors, 14 proliferative nodules arising in congenital nevi, 1 nevus during pregnancy) and 30 melanocytic lesions from 3 patients with family history of uveal melanoma and BAP1 germline mutation. Most sporadic melanocytic lesions exhibited positive BAP1 nuclear staining, except for 1 proliferative nodule arising in congenital nevus, 1 desmoplastic, 1 nevoid, and 2 metastatic melanomas. BRAFV600E positivity was demonstrated in 80% of dermal, 5% of congenital, 6% of Spitz, and 5.5% of atypical Spitz nevi; 29% of proliferative nodules arising in congenital nevi; and 24% of primary and nondesmoplastic and 35% of metastatic melanomas. Combined BAP1 loss and BRAFV600E staining was seen in 67% of BAP1 tumor syndrome-associated lesions and in none of the sporadic melanocytic proliferations including Spitz and atypical Spitz nevi and atypical Spitz tumors, with the exception of 1 primary melanoma. The combined BAP1-BRAFV600E+ immunoprofile appears to be a constant feature of BAP1 tumor syndrome-associated melanocytic lesions, and the designation of Spitz nevi or variants thereof appears to be inaccurate for this group of lesions. PMID:25479927

  2. Dual origin of melanocytes defined by Sox1 expression and their region-specific distribution in mammalian skin.

    PubMed

    Yoshimura, Naoko; Motohashi, Tsutomu; Aoki, Hitomi; Tezuka, Ken-ichi; Watanabe, Natsuki; Wakaoka, Takanori; Era, Takumi; Kunisada, Takahiro

    2013-02-01

    Melanocytes are pigment-producing cells generated from neural crest cells (NCCs) that delaminate from the dorsal neural tube. The widely accepted premise that NCCs migrating along the dorsolateral pathway are the main source of melanocytes in the skin was recently challenged by the finding that Schwann cell precursors are the major cellular source of melanocytes in the skin. Still, in a wide variety of vertebrate embryos, melanocytes are exclusively derived from NCCs. In this study, we show that a NCC population that is not derived from Sox1(+) dorsal neuroepithelial cells but are derived from Sox1(-) cells differentiate into a significant population of melanocytes in the skin of mice. Later, these Sox1(-) cells clearly segregate from cells that originated from Sox1(+) dorsal neuroepithelial cell-derived NCCs. The possible derivation of Sox1(-) cells from epidermal cells also strengthens their non-neuroepithelial origin. PMID:23347447

  3. A Case of Melanoacanthoma: Immunohistochemical Staining Using VECTOR® NovaRED™ to Distinguish Melanocytes from the Cutaneous Pigment

    PubMed Central

    Choi, Jae Eun; Bae, Eui Jong; Kim, Ae Ree; Son, Sang Wook; Song, Hae Jun

    2008-01-01

    Melanoacanthoma is a rare benign mixed tumor of both keratinocytes and melanocytes. Although some authors said that it is a rare variant of seborrheic keratosis, it has clinical and histological features distinct from seborrheic keratosis. It has large dendritic melanin-laden melanocytes throughout all levels of epidermis showing a disruption of melanin transfer from the melanocytes to neighboring keratinocytes. However, it is difficult to distinguish melanocytes clearly from cutaneous pigment in immunohistochemical stain with usually used brown chromogen. We used chromogen with brick-red indicator product (VECTOR® NovaRED™) in S-100 and melan-A immunohistochemical staining to distinguish melanocytes from melanin laden keratinocytes. We suggest that the immunohistochemical staining using this novel chromogen may be useful in the diagnosis of melanoacanthoma.

  4. Imaging pigment chemistry in melanocytic conjunctival lesions with pump-probe microscopy

    NASA Astrophysics Data System (ADS)

    Wilson, Jesse W.; Vajzovic, Lejla; Robles, Francisco E.; Cummings, Thomas J.; Mruthyunjaya, Prithvi; Warren, Warren S.

    2013-03-01

    We extend nonlinear pump-probe microscopy, recently demonstrated to image the microscopic distribution of eumelanin and pheomelanin in unstained skin biopsy sections, to the case of melanocytic conjunctival lesions. The microscopic distribution of pigmentation chemistry serves as a functional indicator of melanocyte activity. In these conjunctival specimens (benign nevi, primary acquired melanoses, and conjunctival melanoma), we have observed pump-probe spectroscopic signatures of eumelanin, pheomelanin, hemoglobin, and surgical ink, in addition to important structural features that differentiate benign from malignant lesions. We will also discuss prospects for an in vivo `optical biopsy' to provide additional information before having to perform invasive procedures.

  5. “Acceptation” et tolérance des allogreffes : nouveau concept

    PubMed Central

    STARZL, Thomas E.

    2010-01-01

    RÉSUMÉ La découverte du microchimérisme dans la transplantation de rein et de foie a permis de mieux comprendre « l’acceptation » des allogreffes, l’analyse des problèmes de conditionnement et la recherche de nouvelles orientations dans le traitement des greffes. En fonction de ce nouveau concept, seront ici discutées les relations avec les maladies infectieuses provoquées par des micro-organismes non cytopathologiques, les réponses aux questions autrefois posées, la réaction immunologique et les implications dans le domaine de l’immunologie générale. PMID:9622934

  6. A Comparison Between Phorbol 12 Myristate 13 Acetate and Phorbol 12, 13 Dibutyrate in Human Melanocyte Culture

    PubMed Central

    Padma, Divya

    2016-01-01

    Introduction Melanocyte culture is an integral part of the studies of skin biology and cosmetic applications. After the introduction of selective medium for the culture of human melanocyte using Phorbol 12-myristate13-acetate (PMA) in 1982, a lot of methods of culturing were tried but till date PMA is a preferred mitogen because of its cost effectiveness compared to growth factors. We have tried to preliminarily evaluate the efficacy of another phorbol ester, Phorbol 12, 13-dibutyrate (PDBu) in melanocyte culture because of its less hydrophobic nature compared to PMA. This property minimizes the trace amount of mitogen in cell culture after washing off and hence does not interfere in other biological assays. Aim To evaluate the differences in the melanocyte survival rate, morphology and mitotic index when grown in media supplemented with PMA and PDBu. Materials and Methods Foreskins were collected from children undergoing circumcision. Epidermal cells were isolated from foreskin and cultured using PMA and PDBu. Melanocytes in culture were monitored for the better establishment and documented. In proliferative assay, melanocytes were treated with PMA and PDBu for 24, 48 and 72 hours and proliferation was measured using 3-(4,5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay method. Results When cultured, melanocytes acquired proliferative status and bipolar morphology quicker in PDBu medium than in PMA medium. Keratinocytes survived as contamination in PMA medium whereas PDBu medium had minimal keratinocytes. MTT assay showed that PDBu has higher proliferative induction capacity than PMA. In even lower concentration of PDBu in medium, melanocytes survived till 72 hours without significant cell loss in compared to PMA medium. Conclusion PDBu can be a valuable replacement for PMA in human melanocyte culture. Higher proliferation induction, unfavourable to keratinocyte survival and less hydrophobicity make PDBu a promising alternative for quicker

  7. Vecteurs Singuliers des Theories des Champs Conformes Minimales

    NASA Astrophysics Data System (ADS)

    Benoit, Louis

    sont elements de la serie h_{p,q}= [ (p(m+2)-qm)^2-4] /(8m(m+2)) ou p,q et m sont des entiers positifs, p et q etant de meme parite, et p+q<= m+2. La charge centrale est donnee par c(m)={3over 2}-{12over m(m+2)} avec m >= 2. Les vecteurs singuliers | Psi_{p,q}> et |Psi_{m-p,m+2-q} > sont respectivement de poids h _{p,q}+pq/2 et h_ {p,q}+(m-p)(m+2-q)/2.. Les vecteurs singuliers ont une norme nulle et on doit les eliminer des representations pour que celles -ci soient unitaires. Cette elimination engendrent des equations (super-)differentielles qui dependent directement de la forme explicite des vecteurs singuliers et auxquelles doivent obeir les fonctions de correlations de la theorie. Ainsi la connaissance de ces vecteurs singuliers est intimement reliee au calcul des fonctions de correlation. Les equations definissant les vecteurs singuliers forment un systeme lineaire surdetermine dont le nombre d'equations est de l'ordre de N(pq), le nombre de partitions de l'entier pq. Puisque les vecteurs singuliers jouent un role capital en theorie conforme, il est naturel de chercher des formes explicites pour les vecteurs (ou pour des familles infinies de ceux -ci). Nous donnons ici la forme explicite pour la famille infinie de vecteurs singuliers ayant un de ses indices egal a 1, pour les algebres de Virasoro et de Neveu-Schwarz. Depuis ces decouvertes, d'autres techniques de construction des vecteurs singuliers ont ete developpees, dont celle de Bauer, Di Francesco, Itzykson et Zuber pour l'algebre de Virasoro qui reproduit directement l'expression explicite des vecteurs singuliers |Psi _{1,q}> et |Psi_{p,1}>. Ils ont utilise l'algebre des produits d'operateurs et la fusion entre representations irreductibles pour engendrer des relations de recurence produisant les vecteurs singuliers. Dans le dernier chapitre de cette these nous adaptons cet algorithme a la construction des vecteurs singuliers de l'algebre de Neveu-Schwarz.

  8. Reticulation des fibres lignocellulosiques

    NASA Astrophysics Data System (ADS)

    Landrevy, Christel

    Pour faire face à la crise économique la conception de papier à valeur ajoutée est développée par les industries papetières. Le but de se projet est l'amélioration des techniques actuelles de réticulation des fibres lignocellulosiques de la pâte à papier visant à produire un papier plus résistant. En effet, lors des réactions de réticulation traditionnelles, de nombreuses liaisons intra-fibres se forment ce qui affecte négativement l'amélioration anticipée des propriétés physiques du papier ou du matériau produit. Pour éviter la formation de ces liaisons intra-fibres, un greffage sur les fibres de groupements ne pouvant pas réagir entre eux est nécessaire. La réticulation des fibres par une réaction de « click chemistry » appelée cycloaddition de Huisgen entre un azide et un alcyne vrai, catalysée par du cuivre (CuAAC) a été l'une des solutions trouvée pour remédier à ce problème. De plus, une adaptation de cette réaction en milieux aqueux pourrait favoriser son utilisation en milieu industriel. L'étude que nous désirons entreprendre lors de ce projet vise à optimiser la réaction de CuAAC et les réactions intermédiaires (propargylation, tosylation et azidation) sur la pâte kraft, en milieu aqueux. Pour cela, les réactions ont été adaptées en milieu aqueux sur la cellulose microcristalline afin de vérifier sa faisabilité, puis transférée à la pâte kraft et l'influence de différents paramètres comme le temps de réaction ou la quantité de réactifs utilisée a été étudiée. Dans un second temps, une étude des différentes propriétés conférées au papier par les réactions a été réalisée à partir d'une série de tests papetiers optiques et physiques. Mots Clés Click chemistry, Huisgen, CuAAC, propargylation, tosylation, azidation, cellulose, pâte kraft, milieu aqueux, papier.

  9. Les superpolynomes symetriques dans les problemes a plusieurs corps de la mecanique quantique supersymetrique

    NASA Astrophysics Data System (ADS)

    Desrosiers, Patrick

    S'inspirant de la supersymetrie, on construit dans cette these une nouvelle generalisation de la theorie des fonctions symetriques. Une theorie physique est supersymetrique si: (1) elle contient des bosons (particules de spin entier) et des fermions (particules de spin demi-entier); (2) elle reste inchangee suite a une transformation des bosons en fermions et vice versa. Les fonctions symetriques dans le superespace (superfonctions symetriques) incorporent a la fois des variables commutatives (bosoniques) et anticommutatives (fermioniques). Ces dernieres engendrent une algebre de Grassmann. Une superfonction symetrique est invariante sous l'echange simultane des variables bosoniques et fermioniques (action diagonale du groupe symetrique); elle se caracterise par une superpartition, i.e., une juxtaposition appropriee de partitions usuelles d'entiers non negatifs. On utilise deux approches dans l'elaboration de la theorie des superfonctions symetriques: l'une provient de la combinatoire et l'autre, de la physique. Suivant la premiere approche, on obtient l'extension des elements standards de la theorie des fonctions symetriques fonctions monomiales, fonctions symetriques elementaires, fonctions completement symetriques, series de puissances, fonctions generatrices et formules de Cauchy. On demontre egalement qu'il existe une extension naturelle, a un parametre, du produit scalaire combinatoire defini par l'orthogonalite des series de puissances dans le superespace. La seconde approche consiste a resoudre des problemes a N corps de la mecanique quantique supersymetrique. On etudie les extensions supersymetriques des modeles Calogero-Moser-Sutherland (CMS), lesquels decrivent l'evolution de particules dont le potentiel d'inter action est proportionnel a l'inverse du carre de la distance separant les particules. Deux modeles supersymetriques CMS sont resolus: trigonometrique (sur un cercle) et rationnel (sur une ligne) avec confinement harmonique. Leurs fonctions d

  10. Actes des Journees de linguistique (Proceedings of the Linguistics Conference) (15th, Quebec, Canada, March 15-16, 2001).

    ERIC Educational Resources Information Center

    Goulet, Marie-Josee, Ed.

    Papers on language research in this volume include the following: "Temporalite en francais de France. Differences dans la conceptualisation du temps et son expression dans un texte narratif oral" ("Differences in the Conceptualization of Time and Its Expression in Oral Narratives") (Natalia Dankova); "La traduction des textes womanist: le cas de…

  11. La singularité du patient tuberculeux dans le système de santé: l'expérience du Burkina Faso

    PubMed Central

    Zerbo, Roger

    2013-01-01

    La démarche pluridisciplinaire s'impose de plus en plus dans le secteur de la santé dans le contexte africain, où les parcours thérapeutiques sont pluriels et les rapports des usagers des centres de santé sont complexes et peu satisfaisants. La compréhension des représentations de la maladie est nécessaire pour offrir des soins appropriés certes, mais l'expérience individuelle des malades représente également une source de savoir. Les données ont été collectées à travers des entretiens semi-directifs, le recueil des récits de vie et des observations participantes. Cet article rend compte d'une expérience d'implication de socio-anthropologue dans la mise en œuvre d'un programme de santé publique au Burkina Faso en vue d'une amélioration de la prise en charge des malades tuberculeux. L'analyse des données à été conduite dans une visée réflexive. Les perspectives socio-anthropologiques ont révélé que l'expérience des anciens malades tuberculeux peut être mise à profit afin d'apporter des changements dans les relations thérapeutiques et l'intégration sociale des autres malades. Cette idée à été mise en application pour tenir lieu d'une traduction des analyses anthropologiques en actes pour un changement. L'article évoque la manière dont l'approche socio-anthropologique au sein d'un programme de santé, peut mettre en évidence le potentiel des malades à être des acteurs importants dans le fonctionnement des services de soins et leur propre bien-être. Dans cette situation, la démarche théorique implique la réflexivité de l'anthropologue, mais également un regard critique sur les modes d'intervention en santé publique. PMID:24009798

  12. Prise en charge des complications des fistules artério-veineuses pour hémodialyse chronique

    PubMed Central

    Jiber, Hamid; Zrihni, Youssef; Zaghloul, Rachid; Hajji, Rita; Zizi, Othman; Bouarhroum, Abdellatif

    2015-01-01

    La fistule artério-veineuse native est l'accès vasculaire de choix pour l'hémodialyse chronique en raison de sa longévité, son taux faible de complication et de mortalité par rapport aux pontages artério-veineux et aux cathéters. Cependant, il arrive assez souvent que l'on assiste à des complications qui sont dominées par la sténose et la thrombose. C'est une étude rétrospective des complications ayants survenues pour 31 fistules artério-veineuses pour hémodialyse chronique des 200 fistules réalisées chez 200 patients au sein du service de chirurgie vasculaire du CHU Hassan II de Fès sur une période de trois ans, étendue de Janvier 2007 à Décembre 2009. Ces complications ont été présentés par les thromboses dans 14 cas soit 45,15% de l'ensemble des complications, les sténoses dans 4 cas (12,90%,) les anévrismes dans 4 cas (12,90%), les complications ischémiques dans 3 cas (9,67%), l'infection dans 3 cas (9,67%), l'hémorragie dans 2 cas (6,45%) et l’ hyperdébit dans un seul cas soit 3,22%. On a pu conserver 22 fistules soit 70,96% par traitement chirurgical ou endovasculaire, on a confectionné une nouvelle fistule dans 8 cas soit 25,80%, et on a adressé une patiente (3,22%) pour pose d'un cathéter veineux tunnelisé permanent. Les complications des fistules artério-veineuses pour l'hémodialyse chronique sont la principale cause de morbidité chez les patients hémodialysés, il est donc important de s'impliquer lors de leur création, et de donner un maximum d'attention quand ils sont manipulés. Ceci suggère la mise en place d'un programme de surveillance de ces fistules en raison de l'impact des complications sur la morbi-mortalité du patient hémodialysé et sur le plan financier. PMID:26113933

  13. Des Moines.

    ERIC Educational Resources Information Center

    Gore, Deborah, Ed.

    1988-01-01

    This document, intended for elementary students, contains articles and activities designed to acquaint young people with the history of Des Moines, Iowa. The articles are short, and new or difficult words are highlighted and defined for young readers. "The Raccoon River Indian Agency" discusses the archeological exploration of the indian…

  14. Symetries et integrabilite des equations aux differences finies

    NASA Astrophysics Data System (ADS)

    Lafortune, Stephane

    2000-09-01

    La présente thèse porte sur l'étude des symétries et des propriétés d'intégrabilité des équations aux différences finies. Dans le chapitre 1, le groupe de symétrie ponctuelle d'un système couplé à deux équations différentielles aux différences est étudié. On montre que dans certains cas, la dimension du groupe peut être infinie. Les équations peuvent décrire l'interaction de deux longues chaînes moléculaires, chacune étant composée d'atomes d'un même type. Dans le chapitre 2, une classe de théories de champs avec interaction exponentielle est introduite. L'interaction dépend de deux matrices de ``couplage'' et est suffisamment générale pour inclure toutes les théories de champs de Toda existant dans la littérature. Les symétries de Lie ponctuelles sont obtenues pour les cas où l'on a un nombre fini, infini ou semi-infini de champs. Une attention spéciale est accordée à la présence de l'invariance conforme. Dans le chapitre 3, nous procédons à la classification et à l'étude d'équations linéarisables. Nous examinons tout d'abord l'équation de Gambier continue qui contient, comme réductions, toutes les équations de deuxième ordre intégrables par linéarisation. Nous introduisons par la suite la forme discrète de cette équation et obtenons les conditions d'intégrabilité à l'aide du confinement des singularités. Nous étudions aussi les différentes réductions du cas discret. De plus, nous obtenons des transformations de Schlesinger pour les équations de Gambier discrète et continue. Dans la dernière partie du chapitre, nous étudions une famille d'équations discrètes du deuxième ordre incluant des équations résolubles par linéarisation. Plusieurs cas intégrables sont obtenus. Dans le cas discret, l'étude de l'intégrabilité est faite à l'aide du confinement des singularités. Dans le chapitre 4, nous étudions un autre critère d'intégrabilité: l'entropie algébrique. Nous montrons que les r

  15. NRAS mutation is the sole recurrent somatic mutation in large congenital melanocytic nevi.

    PubMed

    Charbel, Christelle; Fontaine, Romain H; Malouf, Gabriel G; Picard, Arnaud; Kadlub, Natacha; El-Murr, Nizar; How-Kit, Alexandre; Su, Xiaoping; Coulomb-L'Hermine, Aurore; Tost, Jorg; Mourah, Samia; Aractingi, Selim; Guégan, Sarah

    2014-04-01

    Congenital melanocytic nevus (CMN) is a particular melanocytic in utero proliferation characterized by an increased risk of melanoma transformation during infancy or adulthood. NRAS and BRAF mutations have consistently been reported in CMN samples, but until recently results have been contradictory. We therefore studied a series of large and giant CMNs and compared them with small and medium CMNs using Sanger sequencing, pyrosequencing, high-resolution melting analysis, and mutation enrichment by an enhanced version of ice-COLD-PCR. Large-giant CMNs displayed NRAS mutations in 94.7% of cases (18/19). At that point, the role of additional mutations in CMN pathogenesis had to be investigated. We therefore performed exome sequencing on five specimens of large-giant nevi. The results showed that NRAS mutation was the sole recurrent somatic event found in such melanocytic proliferations. The genetic profile of small-medium CMNs was significantly different, with 70% of cases bearing NRAS mutations and 30% showing BRAF mutations. These findings strongly suggest that NRAS mutations are sufficient to drive melanocytic benign proliferations in utero. PMID:24129063

  16. Gamma-melanocyte-stimulating hormone-like immunoreactivity in blood cells of human eosinophilic patients.

    PubMed

    Johansson, O; Virtanen, M; Hilliges, M; Hansson, L O

    1991-01-01

    The immunohistochemical localization of the peptide gamma-melanocyte-stimulating hormone (gamma-MSH) within human polymorphonuclear leucocytes of blood from eosinophilic patients is described. The gamma-MSH immunoreactivity was observed only in neutrophilic granulocytes leaving all other cell types immuno-negative. PMID:1805488

  17. Loss of tumorigenic potential upon transdifferentiation from keratinocytic into melanocytic lineage

    PubMed Central

    Fehrenbach, Sabrina; Novak, Daniel; Bernhardt, Mathias; Larribere, Lionel; Boukamp, Petra; Umansky, Viktor; Utikal, Jochen

    2016-01-01

    Lineage-specific transcription factors determine the cell fate during development. Direct conversion of several cell types into other lineages has been achieved by the overexpression of specific transcription factors. Even cancer cells have been demonstrated to be amenable to transdifferentiation. Here, we identified a distinct set of transcription factors, which are sufficient to transform cells of the keratinocytic lineage to melanocyte-like cells. Melanocyte marker expression was induced and melanosome formation was observed in non-tumorigenic keratinocytes (HaCaT) and tumorigenic squamous cell carcinoma (MET-4) cells. Moreover, reduced proliferation, cell metabolism, invasion and migration were measured in vitro in transdifferentiated MT-MET-4 cells. A loss of tumorigenic potential of squamous cell carcinoma cells could be due to the upregulation of the melanocyte differentiation associated gene IL-24. Our data show that cells from the keratinocytic lineage can be transdifferented into the melanocytic lineage and provide a proof of principle for a potential new therapeutic strategy. PMID:27387763

  18. Loss of tumorigenic potential upon transdifferentiation from keratinocytic into melanocytic lineage.

    PubMed

    Fehrenbach, Sabrina; Novak, Daniel; Bernhardt, Mathias; Larribere, Lionel; Boukamp, Petra; Umansky, Viktor; Utikal, Jochen

    2016-01-01

    Lineage-specific transcription factors determine the cell fate during development. Direct conversion of several cell types into other lineages has been achieved by the overexpression of specific transcription factors. Even cancer cells have been demonstrated to be amenable to transdifferentiation. Here, we identified a distinct set of transcription factors, which are sufficient to transform cells of the keratinocytic lineage to melanocyte-like cells. Melanocyte marker expression was induced and melanosome formation was observed in non-tumorigenic keratinocytes (HaCaT) and tumorigenic squamous cell carcinoma (MET-4) cells. Moreover, reduced proliferation, cell metabolism, invasion and migration were measured in vitro in transdifferentiated MT-MET-4 cells. A loss of tumorigenic potential of squamous cell carcinoma cells could be due to the upregulation of the melanocyte differentiation associated gene IL-24. Our data show that cells from the keratinocytic lineage can be transdifferented into the melanocytic lineage and provide a proof of principle for a potential new therapeutic strategy. PMID:27387763

  19. ENHANCED BLEACHING TREATMENT: OPPORTUNITIES FOR IMMUNE-ASSISTED MELANOCYTE SUICIDE IN VITILIGO

    PubMed Central

    Webb, Kirsten C.; Eby, Jonathan M.; Hariharan, Vidhya; Hernandez, Claudia; Luiten, Rosalie M.; Le Poole, I. Caroline

    2014-01-01

    Depigmentation in vitiligo occurs by progressive loss of melanocytes from the basal layer of the skin, and can be psychologically devastating to patients. T cell-mediated autoimmunity explains the progressive nature of this disease. Rather than being confronted with periods of rapid depigmentation and bouts of repigmentation, patients with long-standing, treatment-resistant vitiligo can undergo depigmentation treatment. The objective is to remove residual pigmentation in order to achieve a cosmetically acceptable result- that of skin with a uniform appearance. In the USA, only the use of mono-benzyl ether of hydroquinone (MBEH) is approved for this purpose. However, satisfactory results can take time to appear, and there is a risk of repigmentation. MBEH induces necrotic melanocyte death followed by a cytotoxic T cell response to remaining, distant melanocytes. As cytotoxic T cell responses are instrumental to depigmentation, we propose that combining MBEH with immune adjuvant therapies will accelerate immune-mediated melanocyte destruction to achieve faster, more definitive depigmentation than with MBEH alone. Since Toll-like Receptor (TLR) agonists-imiquimod, CpG, and Heat Shock Protein 70 (HSP 70)-all support powerful Th1 responses, we propose that using MBEH in combination with these agents can achieve superior depigmentation results for vitiligo patients. PMID:24840876

  20. The human melanocyte as a particular target for UVA radiation and an endpoint for photoprotection assessment.

    PubMed

    Marrot, L; Belaidi, J P; Meunier, J R; Perez, P; Agapakis-Causse, C

    1999-06-01

    The induction of DNA breaks by UVA (320-400 nm) in the nucleus of normal human melanocytes in culture was investigated using single cell gel electrophoresis, also called the comet assay. Endogenous pigment and/or melanin-related molecules were found to enhance DNA breakage: comets were more intense in melanocytes than in fibroblasts, in cells with high melanin content or after stimulation of melanogenesis by supplying tyrosine in the culture medium. After UVA doses where strong comets were observed, neither cytotoxicity nor stimulation of tyrosinase activity were detected. However, the accumulation of p53 protein suggested that cells reacted to genotoxic stress under these experimental conditions. The same approach was used to compare two sunscreens with identical sun protection factors but different UVA protection factors. The results presented in this paper suggest that human melanocytes may be used as a target cell to evidence broadspectrum photoprotection. Moreover, these data appear to be helpful in getting a better understanding of the role of sunlight in the initiating steps of melanocyte transformation. PMID:10378007

  1. Postnatal lineage mapping of follicular melanocytes with the Tyr::CreER(T) (2) transgene.

    PubMed

    Harris, Melissa L; Pavan, William J

    2013-03-01

    One of the main advantages of using inducible and conditional transgenes to study pigment cell biology is that they allow for genetic manipulation within melanocytes after roles in general neural crest or melanoblast development have been fulfilled. Specifically, we focus here on the ability of the Tyr::CreER(T) (2) transgenic line to alter genes within follicular melanocytes postnatally. Using the Gt(ROSA)26Sor(tm1sor) reporter allele, we present in detail the expression and activity of Tyr::CreER(T) (2) when induced during hair morphogenesis and adult hair cycling. We find that despite similarities in expression pattern to endogenous TYR, Tyr::CreER(T) (2) is effective at targeting both undifferentiated and differentiated melanocytes within the hair follicle. We also find that Tyr::CreER(T) (2) provides the highest levels of recombination when induced during the early phases of hair growth. In conclusion, the descriptions provided here will guide future analyses of gene function within the melanocyte system of the hair follicle when using this Tyr::CreER(T) (2) transgene. PMID:23176440

  2. Development of a three-dimensional surface imaging system for melanocytic skin lesion evaluation

    NASA Astrophysics Data System (ADS)

    Tosca, Androniki; Kokolakis, Athanasios; Lasithiotakis, Konstantinos; Zacharopoulos, Athanasios; Zabulis, Xenophon; Marnelakis, Ioannis; Ripoll, Jorge; Stephanidis, Constantine

    2013-01-01

    Even though surface morphology is always taken into account when assessing clinically pigmented skin lesions, it is not captured by most modern imaging systems using digital imaging. Our aim is to develop a novel three-dimensional (3D) imaging technique to record detailed information of the surface anatomy of melanocytic lesions that will enable improved classification through digital imaging. The apparatus consists of three high-resolution cameras, a light source, and accompanying software. Volume measurements of specific phantoms using volumetric tubes render slightly lower values than those obtained by our 3D imaging system (mean%±SD, 3.8%±0.98, P<0.05). To examine the reproducibility of the method, sequential imaging of melanocytic lesions is carried out. The mean%±SD differences of area, major axis length, volume, and maximum height are 2.1%±1.1, 0.9%±0.8, 3.8%±2.9, and 2.5%±3.5, respectively. Thirty melanocytic lesions are assessed, including common and dysplastic nevi and melanomas. There is a significant difference between nevi and melanomas in terms of variance in height and boundary asymmetry (P<0.001). Moreover, dysplastic nevi have significantly higher variances in pigment density values than common nevi (P<0.001). Preliminary data suggest that our instrument has great potential in the evaluation of the melanocytic lesions. However, these findings should be confirmed in larger-scale studies.

  3. FGF2 regulates melanocytes viability through the STAT3-transactivated PAX3 transcription

    PubMed Central

    Dong, L; Li, Y; Cao, J; Liu, F; Pier, E; Chen, J; Xu, Z; Chen, C; Wang, R-a; Cui, R

    2012-01-01

    PAX3 (paired box 3) is known to have an important role in melanocyte development through modulation of microphthalmia-associated transcription factor transcription. Here we found that PAX3 transcriptional activity could be regulated through FGF2 (basic fibroblast growth factor)-STAT3 (signal transducer and activator of transcription 3) signaling in the pigment cells. To study its function in vivo, we have generated a transgenic mouse model expressing PAX3 driven by tyrosinase promoter in a tissue-specific fashion. These animals exhibit hyperpigmentation in the epidermis, evident in the skin color of their ears and tails. We showed that the darker skin color results from both increased melanocyte numbers and melanin synthesis. Together, our study delineated a novel pathway in the melanocyte lineage, linking FGF2-STAT3 signaling to increased PAX3 transcription. Moreover, our results suggest that this pathway might contribute to the regulation of melanocyte numbers and melanin levels, and thereby provide an alternative strategy to induce pigmentation. PMID:21997191

  4. CRH stimulation of corticosteroids production in melanocytes is mediated by ACTH.

    PubMed

    Slominski, Andrzej; Zbytek, Blazej; Szczesniewski, Andrzej; Semak, Igor; Kaminski, Jan; Sweatman, Trevor; Wortsman, Jacobo

    2005-04-01

    The response to systemic stress is organized along the hypothalamic-pituitary-adrenal axis (HPA), whereas the response to a peripheral stress (solar radiation) is mediated by epidermal melanocytes (cells of neural crest origin) responsible for the pigmentary reaction. Melanocytes express proopiomelanocortin (POMC), corticotropin-releasing hormone (CRH), and CRH receptor-1 (CRH-R1) and can produce corticosterone. In the present study, incubation of normal epidermal melanocytes with CRH was found to trigger a functional cascade structured hierarchically and arranged along the same algorithm as in the HPA axis: CRH activation of CRH-R1 stimulated cAMP accumulation and increased POMC gene expression and production of ACTH. CRH and ACTH also enhanced production of cortisol and corticosterone, and cortisol production was also stimulated by progesterone. The chemical identity of the cortisol was confirmed by liquid chromatography-mass spectrometry (LC/MS2) with [corrected] mass spectrometry-mass spectrometry analyses. POMC gene silencing abolished the stimulatory effect of CRH on corticosteroid synthesis, indicating that this is indirect and mediated via production of ACTH. Thus the melanocyte response to CRH is highly organized along the same functional hierarchy as the HPA axis. This pattern demonstrates the fractal nature of the response to stress with similar activation sequence at the single-cell and whole body levels. PMID:15572653

  5. The immunology and inflammatory responses of human melanocytes in infectious diseases.

    PubMed

    Gasque, Philippe; Jaffar-Bandjee, Marie Christine

    2015-10-01

    Melanin is a canonical and major defense molecule in invertebrates but its role in mammalian immunity remains unexplored. In contrast, several recent studies have highlighted the emerging innate immune activities of human melanin-producing cells which can sense and respond to bacterial and viral infections. Indeed, the skin is a major portal of entry for pathogens such as arboviruses (Chikungunya, Dengue) and bacteria (mycobacterium leprae, Leptospira spirochetes). Melanocytes of the epidermis could contribute to the phagocytosis of these invading pathogens and to present antigens to competent immune cells. Melanocytes are known to produce key cytokines such as IL-1β, IL6 and TNF-α as well as chemokines. These molecules will subsequently alert macrophages, neutrophils, fibroblasts and keratinocytes through unique crosstalk mechanisms. The infection and the inflammatory responses will control melanocyte's immune and metabolic functions and could contribute to skin manifestations (rash, hyper or de-pigmentation, epidermolysis and psoriasis-like lesions). This review will address the potential role of melanocytes in immunity, inflammation and infection of the skin in health and diseases. PMID:26092350

  6. Effects of PGF{sub 2{alpha}} on human melanocytes and regulation of the FP receptor by ultraviolet radiation

    SciTech Connect

    Scott, Glynis . E-mail: Glynis_Scott@urmc.rochester.edu; Jacobs, Stacey; Leopardi, Sonya; Anthony, Frank A.; Learn, Doug; Malaviya, Rama; Pentland, Alice

    2005-04-01

    Prostaglandins are potent lipid hormones that activate multiple signaling pathways resulting in regulation of cellular growth, differentiation, and apoptosis. In the skin, prostaglandins are rapidly released by keratinocytes following ultraviolet radiation and are chronically present in inflammatory skin lesions. We have shown previously that melanocytes, which provide photoprotection to keratinocytes through the production of melanin, express several receptors for prostaglandins, including the PGE{sub 2} receptors EP{sub 1} and EP{sub 3} and the PGF{sub 2{alpha}} receptor FP, and that PGF{sub 2{alpha}} stimulates melanocyte dendricity. We now show that PGF{sub 2{alpha}} stimulates the activity and expression of tyrosinase, the rate-limiting enzyme in melanin synthesis. Analysis of FP receptor regulation showed that the FP receptor is regulated by ultraviolet radiation in melanocytes in vitro and in human skin in vivo. We also show that ultraviolet irradiation stimulates production of PGF{sub 2{alpha}} by melanocytes. These results show that PGF{sub 2{alpha}} binding to the FP receptor activates signals that stimulate a differentiated phenotype (dendricity and pigmentation) in melanocytes. The regulation of the FP receptor and the stimulation of production of PGF{sub 2{alpha}} in melanocytes in response to ultraviolet radiation suggest that PGF{sub 2{alpha}} could act as an autocrine factor for melanocyte differentiation.

  7. The usefulness of c-Kit in the immunohistochemical assessment of melanocytic lesions

    PubMed Central

    Pilloni, L.; Bianco, P.; Difelice, E.; Cabras, S.; Castellanos, M.E.; Atzori, L.; Ferreli, C.; Mulas, P.; Nemolato, S.; Faa, G.

    2011-01-01

    C-Kit (CD117), the receptor for the stem cell factor, a growth factor for melanocyte migration and proliferation, has shown differential immunostaining in various benign and malignant melanocytic lesions. The purpose of this study is to compare c-Kit immunostaining in benign nevi and in primary and metastatic malignant melanomas, to determine whether c-Kit can aid in the differential diagnosis of these lesions. c-Kit immunostaining was performed in 60 cases of pigmented lesions, including 39 benign nevi (5 blue nevi, 5 intra-dermal nevi, 3 junctional nevi, 15 cases of primary compound nevus, 11 cases of Spitz nevus), 18 cases of primary malignant melanoma and 3 cases of metastatic melanoma. The vast majority of nevi and melanomas examined in this study were positive for c-Kit, with minimal differences between benign and malignant lesions. C-Kit cytoplasmatic immunoreactivity in the intraepidermal proliferating nevus cells, was detected in benign pigmented lesions as well as in malignant melanoma, increasing with the age of patients (P=0.007) in both groups. The patient’s age at presentation appeared to be the variable able to cluster benign and malignant pigmented lesions. The percentage of c-Kit positive intraepidermal nevus cells was better associated with age despite other variables (P=0.014). The intensity and percentage of c-Kit positivity in the proliferating nevus cells in the dermis was significantly increased in malignant melanocytic lesions (P=0.015 and P=0.008) compared to benign lesions (compound melanocytic nevi, Spitz nevi, intradermal nevi, blue nevi). Immunostaning for c-Kit in metastatic melanomas was negative. Interestingly in two cases of melanoma occurring on a pre-existent nevus, the melanoma tumor cells showed strong cytoplasmatic and membranous positivity for c-kit, in contrast with the absence of any immunoreactivity in pre-existent intradermal nevus cells. C-Kit does not appear to be a strong immunohistochemical marker for distinguishing

  8. Melanocyte expression of Survivin promotes development and metastasis of UV-induced melanoma in HGF-transgenic mice

    PubMed Central

    Thomas, Joshua; Liu, Tong; Cotter, Murray A.; Florell, Scott R.; Robinette, Kyle; Hanks, Adrianne N.; Grossman, Douglas

    2008-01-01

    We previously found the apoptosis inhibitor Survivin to be expressed in melanocytic nevi and melanoma, but not in normal melanocytes. To investigate the role of Survivin in melanoma development and progression, we examined the consequences of forced Survivin expression in melanocytes in vivo. Transgenic (Tg) mouse lines (Dct-Survivin) were generated with melanocyte-specific expression of Survivin, and melanocytes grown from Dct-Survivin mice expressed Survivin. Dct-Survivin melanocytes exhibited decreased susceptibility to UV-induced apoptosis but no difference in proliferative capacity compared to melanocytes derived from non-Tg littermates. Induction of nevi in Dct-Survivin and non-Tg mice by topical application of DMBA did not reveal significant differences in lesion onset (median 10 wks) or density (4 lesions/mouse after 15 wks). Dct-Survivin mice were bred with melanoma-prone MH19/HGF-B6 Tg mice and all progeny expressing either individual, neither, or both (Survivin/HGF) transgenes were UV-treated as neonates and then monitored for 43 wks. Melanocytes in neonatal Survivin+/HGF+ mouse skin were less susceptible to UV-induced apoptosis than those from Survivin−/HGF+ mice. Onset of melanocytic tumors was earlier (median 18 vs. 24 wks, p = .01, log-rank test) and overall tumor density was greater (7.7 vs. 5.2 tumors/mouse, p = .04) in Survivin+/HGF+ compared to Survivin−/HGF+ mice. Strikingly, melanomas arising in Survivin+/HGF+ mice demonstrated a greater tendency for lymph node (35% vs. 0%, p = .04) and lung (53% vs. 22%) metastasis, and lower rates of spontaneous apoptosis, than those in Survivin−/HGF+ mice. These studies demonstrate a role for Survivin in promoting both early and late events of UV-induced melanoma development in vivo. PMID:17545596

  9. Pigmented median raphe cyst of the penis with consideration of the possible mechanism of melanocytic colonization: A case report

    PubMed Central

    ISHIDA, MITSUAKI; IWAI, MUNEO; YOSHIDA, KEIKO; KAGOTANI, AKIKO; OKABE, HIDETOSHI

    2014-01-01

    Median raphe cyst is a rare lesion located on the median raphe. The cyst wall is lined by cuboidal to columnar cells, transitional (urothelial) cells, stratified squamous cells or a mixture of these. The normal urethral mucosa and the median raphe cyst usually lack melanocytes and/or melanin pigment. However, albeit extremely rare, the presence of melanin pigment and/or melanocytes in median raphe cyst, namely pigmented median raphe cyst, has been previously reported. The current case report presents the sixth case of pigmented median raphe cyst and discusses the possible mechanism of melanocytic colonization in this tumor. A 48-year-old male presented with a nodule on the ventral surface of the penis. Histopathological study revealed that the cyst wall was covered by uniform bland cuboidal to urothelial cells. The peculiar observation was the presence of dendritic melanocytes among the epithelial cells. Therefore, a diagnosis of pigmented median raphe cyst was determined. Immunohistochemically, stem cell factor and endothelin-1 were not expressed in the epithelial cells of the cyst wall. It is well-known that melanocytes are rarely found in various non-melanocytic tumors, a phenomenon termed ‘colonization’. The mechanism by which melanocytes appear in median raphe cyst remains unclear. The present report is the first to demonstrate that melanocytic proliferation and differentiation factors, such as stem cell factor and endothelin-1, are not involved in the pigmentation of median raphe cyst. In addition, aberrant melanocytic migration may contribute to the development of this type of lesion. PMID:24396444

  10. Inhibitory effect of Korean Red Ginseng on melanocyte proliferation and its possible implication in GM-CSF mediated signaling

    PubMed Central

    Oh, Chang Taek; Park, Jong Il; Jung, Yi Ra; Joo, Yeon Ah; Shin, Dong Ha; Cho, Hyoung Joo; Ahn, Soo Mi; Lim, Young-Ho; Park, Chae Kyu; Hwang, Jae Sung

    2013-01-01

    Korean Red Ginseng (KRG) has been reported to exert anticancer, anti-oxidant, and anti-inflammatory effects. However, there has been no report on the effect of KRG on skin pigmentation. In this study, we investigated the inhibitory effect of KRG on melanocyte proliferation. KRG extract (KRGE) at different concentrations had no effect on melanin synthesis in melan-A melanocytes. Saponin of KRG (SKRG) inhibited melanin content to 80% of the control at 100 ppm. Keratinocyte-derived factors induced by UV-irradiation were reported to stimulate melanogenesis, differentiation, proliferation, and dendrite formation. In this study, treatment of melan-A melanocytes with conditioned media from UV-irradiated SP-1 keratinocytes increased melanocyte proliferation. When UV-irradiated SP-1 keratinocytes were treated with KRGE or SKRG, the increase of melanocyte proliferation by the conditioned media was blocked. Granulocyte-macrophage colony-stimulating factor (GM-CSF) was produced and released from UV-irradiated keratinocytes. This factor has been reported to be involved in regulating the proliferation and differentiation of epidermal melanocytes. In this study, GM-CSF was significantly increased in SP-1 keratinocytes by UVB irradiation (30 mJ/cm2), and the proliferation of melan-A melanocytes increased significantly by GM-CSF treatment. In addition, the proliferative effect of keratinocyte-conditioned media on melan-A melanocytes was blocked by anti-GM-CSF treatment. KRGE or SKRG treatment decreased the expression of GM-CSF in SP-1 keratinocytes induced by UVB irradiation. These results demonstrate that UV irradiation induced GM-CSF expression in keratinocytes and KRGE or SKRG inhibited its expression. Therefore, KRG could be a good candidate for regulating UV-induced melanocyte proliferation. PMID:24235857

  11. Smyth chicken melanocyte autoantibodies: cross-species recognition, in vivo binding, and plasma membrane reactivity of the antiserum.

    PubMed

    Searle, E A; Austin, L M; Boissy, Y L; Zhao, H; Nordlund, J J; Boissy, R E

    1993-06-01

    Smyth line (SL) chickens, which develop a depigmenting disorder similar to human vitiligo, produce circulating anti-melanocyte antibodies (Austin, L.M. et al., (1992) The detection of melanocyte autoantibodies in the Smyth chicken model for vitiligo. Clin. Immunol. Immunopathol., 64:112-120). In order to characterize these autoantibodies, we studied the reactivity of cultured chicken, mouse, and human melanocytes, as well as frozen sections of chicken feather follicles and embryonic eyes, against SL serum, employing indirect immunofluorescence. Light Brown Leghorn (LBL) serum was used as a negative control. Chicken (SL and LBL), mouse, and human melanocytes exhibited greater fluorescence with SL serum than with LBL serum (up to a 1:60,000 dilution). The fluorescent pattern was predominant along the perimeter of the cells, suggesting plasma membrane staining. Fluorescence-activated flow cytometry analysis and immunocytochemical localization at the ultrastructural level using intact chicken cells supported this hypothesis. Melanocytes were readily stained in cryosections of regenerating feather follicles and embryonic eyes incubated with SL, but not LBL, serum. In addition, amelanotic melanocytes in albino chicken feathers reacted with SL serum. SL serum also preferentially stained cells emigrating from cultured avian neural tubes and within the dermis of the proliferative germ of regenerating feather follicles suggesting that melanoblasts express the antigens. We conclude that Smyth line serum contains melanocyte autoantibodies that cross-react with mouse and human melanocytes, are able to bind to pigment cells within tissues, and recognize antigens expressed in the cytoplasm and on the surface of melanocytes and melanoblasts. PMID:8234200

  12. Aspects épidémiologiques des accidents vasculaires cérébraux (AVC) aux urgences de l'institut de cardiologie d'Abidjan (ICA)

    PubMed Central

    N'goran, Yves N'da Kouakou; Traore, Fatou; Tano, Micesse; Kramoh, Kouadio Euloge; Kakou, Jean-Baptiste Anzouan; Konin, Christophe; Kakou, Maurice Guikahue

    2015-01-01

    Introduction L'objectif de notre étude était de décrire les caractéristiques sociodémographiques et les Facteurs de Risque cardio-Vasculaires (FRV) des patients admis pour accidents vasculaires cérébraux (AVC) dans un service autre que celui de la neurologie. Méthodes Étude transversale rétrospective sur une période de 2 ans (janv. 2010 et déc. 2011), réalisée aux urgences de l'institut de cardiologie d'Abidjan. Résultats Il s'agissait de 176 adultes avec un âge moyen de 60 ans, une prédominance féminine. Les facteurs de risque majeurs retrouvés étaient l'hypertension artérielle dans 86,4% des cas, le diabète dans 11,4% des cas, le tabagisme dans 2,2% des cas. Les motifs de consultation étaient la perte de connaissance dans 36,4% des cas, l'hémiplégie dans 31,8% des cas, les céphalées dans 17,4% des cas, les vertiges dans 10,9% et les palpitations dans 2,2% des cas. La tension artérielle systolique moyenne était à 174 mmHg, la tension artérielle diastolique moyenne était à 105 mmHg et la pression pulsée moyenne était à 70 mmHg. Les AVC étaient associés à une arythmie complète par fibrillation auriculaire dans 11,4% des cas. Les AVC ischémiques représentaient 84,1%. L’évolution aux urgences a été marquée par un décès dans 17% (30) des cas. Conclusion Les AVC constituent un problème majeur de santé publique. Malgré sa prédominance féminine, ils (AVC) touchaient 44% des hommes dans notre étude lorsqu'on sait qu'en Afrique l'activité sociale repose sur les hommes. Ils restent une pathologie grave par la forte létalité. PMID:26327997

  13. Active Notch1 Confers a Transformed Phenotype to Primary Human Melanocytes

    PubMed Central

    Pinnix, Chelsea C.; Lee, John T.; Liu, Zhao-Jun; McDaid, Ronan; Balint, Klara; Beverly, Levi J.; Brafford, Patricia A.; Xiao, Min; Himes, Benjamin; Zabierowski, Susan E.; Yashiro-Ohtani, Yumi; Nathanson, Katherine L.; Bengston, Ana; Pollock, Pamela M.; Weeraratna, Ashani T.; Nickoloff, Brian J.; Pear, Warren S.; Capobianco, Anthony J.; Herlyn, Meenhard

    2009-01-01

    The importance of MAPK signaling in melanoma is underscored by the prevalence of activating mutations in N-Ras and B-Raf; yet, clinical development of inhibitors of this pathway has been largely ineffective, suggesting that alternative oncogenes may also promote melanoma. Notch is an interesting candidate that has only been correlated with melanoma development and progression; a thorough assessment of tumor-initiating effects of activated Notch on human melanocytes would clarify the mounting correlative evidence and perhaps identify a novel target for an otherwise untreatable disease. Analysis of a substantial panel of cell lines and patient lesions demonstrated that Notch activity is significantly higher in melanomas than their non-transformed counterparts. The use of a constitutively-active, truncated Notch transgene construct (NIC) was exploited to determine if Notch activation is a ‘driving’ event in melanocytic transformation or instead a ‘passenger’ event associated with melanoma progression. NIC-infected melanocytes displayed increased proliferative capacity and biological features more reminiscent of melanoma such as dysregulated cell adhesion and migration. Gene expression analyses supported these observations and aided in the identification of MCAM, an adhesion molecule associated with acquisition of the malignant phenotype, as a direct target of Notch transactivation. NIC-positive melanocytes grew at clonal density, proliferated in limiting media conditions, and also exhibited anchorage-independent growth suggesting that Notch, alone, is a transforming oncogene in human melanocytes, a phenomenon not previously described for any melanoma oncogene; this new information yields valuable insight into the basic epidemiology of melanoma and launches a realm of possibilities for drug intervention in this deadly disease. PMID:19549918

  14. Diagnosis and staging of female genital tract melanocytic lesions using pump-probe microscopy (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Robles, Francisco E.; Selim, Maria A.; Warren, Warren S.

    2016-02-01

    Melanoma of the vulva is the second most common type of malignancy afflicting that organ. This disease caries poor prognosis, and shows tendencies to recur locally and develop distant metastases through hematogenous dissemination. Further, there exists significant clinical overlap between early-stage melanomas and melanotic macules, benign lesions that are believed to develop in about 10% of the general female population. In this work we apply a novel nonlinear optical method, pump-probe microscopy, to quantitatively analyze female genitalia tract melanocytic lesions. Pump-probe microscopy provides chemical information of endogenous pigments by probing their electronic excited state dynamics, with subcellular resolution. Using unstained biopsy sections from 31 patients, we find significant differences between melanin type and structure in tissue regions with invasive melanoma, melanoma in-situ and non-malignant melanocytic proliferations (e.g., nevi, melanocytic macules). The molecular images of non-malignant lesion have a well-organized structure, with relatively homogenous pigment chemistry, most often consistent with that of eumelanin with large aggregate size or void of metals, such as iron. On the other hand, pigment type and structure observed in melanomas in-situ and invasive melanomas is typically much more heterogeneous, with larger contributions from pheomelanin, melanins with larger metal content, and/or melanins with smaller aggregate size. Of most significance, clear differences can be observed between melanocytic macules and vulvar melanoma in-situ, which, as discussed above, can be difficult to clinically distinguish. This initial study demonstrates pump-probe microscopy's potential as an adjuvant diagnostic tool by revealing systematic chemical and morphological differences in melanin pigmentation among invasive melanoma, melanoma in-situ and non-malignant melanocytic lesions.

  15. Effects of hypergravity on the expression of multidrug resistance proteins in human melanocytic cells

    NASA Astrophysics Data System (ADS)

    Lambers, B.; Stieber, C.; Grigorieva, O.; Block, I.; Bromeis, B.; Buravkova, L.; Gerzer, R.; Ivanova, K.

    In humans the skin serves as a barrier against potentially harmful effects of the environment Human melanocytes constitute the principal cells for skin pigmentation by synthesizing the pigment melanin Melanin acts as a scavenger for free radicals that may arise during metabolic stress The melanocytes are also able to secrete a wide range of signal molecules In previous studies we found that normal human melanocytes NHMs and non-metastatic melanoma cells respond to long-time exposure to hypergravity up to 5 g for 24 h with elevated efflux of guanosine 3 5 -cyclic monophosphate cGMP in the presence of phosphodiesterase PDE inhibitors e g 3-isobutyl-1-methylxanthine Cyclic GMP is known to play a signaling role in human melanocyte physiology It controls the signaling activities of nitric oxide NO in relation to melanogenesis as well as in melanocyte-extracellular matrix interactions that may be important for some pathological processes including metastasis The present study investigated the effects of hypergravity on the expression of the multidrug resistance proteins MRP 4 and 5 as highly selective cGMP exporters in non-stimulated and NO-stimulated NHMs and melanoma cells MCs on mRNA levels using semi-quantitative RT-PCR analysis Hypergravity up to 5 g for 24 h was produced by horizontal centrifugal acceleration The NONOate DETA-NO 0 1 mM was used as a direct NO donor for cell stimulation For 5-g experiments the mRNA levels for the highly specific cGMP transporter MRP5 appeared to be

  16. Biological characterization of human fibroblast-derived mitogenic factors for human melanocytes.

    PubMed Central

    Imokawa, G; Yada, Y; Morisaki, N; Kimura, M

    1998-01-01

    To clarify the paracrine linkage between human fibroblasts and melanocytes in cutaneous pigmentation, we studied the effects of human fibroblast-derived factors on the proliferation of human melanocytes. In medium conditioned for 4 days with human fibroblast culture, factors were produced that markedly stimulated DNA synthesis of human melanocytes. The stimulatory effect was higher in medium conditioned with fibroblasts from aged skin than in medium conditioned with fibroblasts from young skin, and was interrupted by inhibitors of tyrosine kinase, such as tyrphostin, genistein and herbimycin, but not by inhibitors of protein kinases C and A, such as H-7 and phloretin. The conditioned medium was also capable of activating mitogen-activated protein kinase of human melanocytes, with old fibroblasts being more effective than young ones. Analysis of factors released into the conditioned medium revealed that levels of hepatocyte growth factor (HGF) and stem cell factor (SCF) were increased in old-fibroblast-conditioned medium compared with young-fibroblast-conditioned medium. In contrast, levels of basic fibroblast growth factor (bFGF) were similar in both media. When the conditioned medium was treated with HGF antibody with or without SCF antibody, the increase in DNA synthesis by human melanocytes was decreased to 20% of the elevated level, whereas antibodies to bFGF had no effect. Analysis of the medium conditioned for 4 days after cytokine application demonstrated that, of the cytokines tested, interleukin 1alpha and tumour necrosis factor alpha are highly effective in stimulating HGF secretion by old fibroblasts. HGF and SCF, but not bFGF, were markedly increased in culture medium in the presence of IL-1alpha, and this stimulatory effect was confined to young human fibroblasts. These findings suggest that SCF and HGF derived from human fibroblasts may play a part in regulating cutaneous pigmentation during inflammation and aging. PMID:9494091

  17. L'astronomie dans le monde

    NASA Astrophysics Data System (ADS)

    Manfroid, J.

    2014-06-01

    Future lune ? - L'âge de la Lune - Des volcans actifs sur Vénus - Un lac dans le cratère Gusev ? - Météorites et atmosphère martiennes - L’hexagone de Saturne - Pluton - Exo-Terre - Bêta Pictoris b - Cérès et Vesta depuis Mars - Naine froide - Parallaxes par Hubble - L2 Puppis et le sort du Soleil - Supernova et lentille gravitationnelle - Champ magnétique galactique - L’objet de Sakurai - Fermi et la matière noire - Lentille naine

  18. La planification préalable des soins pour les patients en pédiatrie

    PubMed Central

    2008-01-01

    RÉSUMÉ Les progrès médicaux et technologiques ont permis d’ac-croître les taux de survie et d’améliorer la qualité de vie des nourrissons, des enfants et des adolescents ayant des maladies chroniques mettant la vie en danger. La planifi-cation préalable des soins inclut le processus relié aux discussions sur les traitements essentiels au maintien de la survie et la détermination des objectifs des soins de longue durée. Les dispensateurs de soins pédiatriques ont l’obligation éthique d’assimiler cet aspect des soins médicaux. Le présent document de principes vise à aider les dispensateurs de soins à discuter de la planification préalable des soins des patients pédiatriques dans diverses situations. La planification préalable des soins exige des communications efficaces afin de clarifier les objectifs des soins et de s’entendre sur les traitements pertinents ou non pour réaliser ces objectifs, y compris les mesures de réanimation et les mesures palliatives.

  19. Etude des phenomenes dynamiques ultrarapides et des caracteristiques impulsionnelles d'emission terahertz du supraconducteur YBCO

    NASA Astrophysics Data System (ADS)

    Savard, Stephane

    Les premieres etudes d'antennes a base de supraconducteurs a haute temperature critique emettant une impulsion electromagnetique dont le contenu en frequence se situe dans le domaine terahertz remontent a 1996. Une antenne supraconductrice est formee d'un micro-pont d'une couche mince supraconductrice sur lequel un courant continu est applique. Un faisceau laser dans le visible est focalise sur le micro-pont et place le supraconducteur dans un etat hors-equilibre ou des paires sont brisees. Grace a la relaxation des quasiparticules en surplus et eventuellement de la reformation des paires supraconductrices, nous pouvons etudier la nature de la supraconductivite. L'analyse de la cinetique temporelle du champ electromagnetique emis par une telle antenne terahertz supraconductrice s'est averee utile pour decrire qualitativement les caracteristiques de celle-ci en fonction des parametres d'operation tels que le courant applique, la temperature et la puissance d'excitation. La comprehension de l'etat hors-equilibre est la cle pour comprendre le fonctionnement des antennes terahertz supraconductrices a haute temperature critique. Dans le but de comprendre ultimement cet etat hors-equilibre, nous avions besoin d'une methode et d'un modele pour extraire de facon plus systematique les proprietes intrinseques du materiau qui compose l'antenne terahertz a partir des caracteristiques d'emission de celle-ci. Nous avons developpe une procedure pour calibrer le spectrometre dans le domaine temporel en utilisant des antennes terahertz de GaAs bombarde aux protons H+ comme emetteur et detecteur. Une fois le montage calibre, nous y avons insere une antenne emettrice dipolaire de YBa 2Cu3O7-delta . Un modele avec des fonctions exponentielles de montee et de descente du signal est utilise pour lisser le spectre du champ electromagnetique de l'antenne de YBa 2Cu3O7-delta, ce qui nous permet d'extraire les proprietes intrinseques de ce dernier. Pour confirmer la validite du modele

  20. Les fluctuations supraconductrices dans le compose praseodyme-cerium-oxyde de cuivre

    NASA Astrophysics Data System (ADS)

    Renaud, Jacques

    Ce travail etudie les fluctuations supraconductrices dans le compose supraconducteur a haute temperature critique dope aux electrons Pr2-xCe xCuO4+delta. La technique utilisee pour sonder ces fluctuations est le transport electrique DC dans le plan ab. Il s'agit, a notre connaissance, de la premiere etude de ce type dans la classe generale des supraconducteurs a haute temperature critique dopes aux electrons et, plus particulierement, dans Pr2-xCe xCuO4+delta. De plus, l'etude est effectuee pour trois regimes de dopage, soit sous-dope x = 0.135, dopage optimal x = 0.15 et surdope x = 0.17. Les echantillons etudies sont des couches minces d'epaisseur plus grande que 100 nm crues par ablation laser. Les mesures electriques DC effectuees dans ce travail sont la resistance en reponse lineaire et les courbes IV en reponse non lineaire en fonction de la temperature. La mise en oeuvre experimentale de ces mesures a necessite une grande attention au filtrage et aux effets de chauffage a haut courant. Nous montrons que, sans cette attention, les donnees experimentales sont toujours erronees dans le regime pertinent pour nos echantillons. Les resultats pour le dopage optimal x = 0.15 sont expliques de facon tres convaincante dans le cadre de fluctuations purement 2D. D'abord, le regime des fluctuations gaussiennes est tres bien decrit par le modele d'Aslamazov-Larkin en deux dimensions. Ensuite, le regime de fluctuations critiques, se trouvant a plus basse temperature que le regime gaussien, est tres bien decrit par la physique 2D de Kosterlitz-Thouless. Dans cette analyse, les deux regimes ont des temperatures critiques coherentes entre elles, ce qui semble confirmer ce scenario 2D. Une analyse des donnees dans le cadre de fluctuations 3D est exploree mais donne des conclusions incoherentes. Les resultats pour les autres dopages sont qualitativement equivalents avec le dopage optimal et permettent donc une explication purement 2D. Par contre, contrairement au dopage optimal

  1. Les sarcomes des tissus mous: à propos de 33 cas

    PubMed Central

    Abdou, Jiddou; Elkabous, Mustapha; M'rabti, Hind; Errihani, Hassan

    2015-01-01

    L'objectif de cette étude est de rapporter les particularités épidémiologiques, cliniques, histologiques, thérapeutiques et évolutives des sarcomes des tissus mous à l'Institut National d'Oncologie et de définir les facteurs influençant la survie des patients. C'est une étude rétrospective de 33 cas de sarcome des tissus mous, colligés entre janvier 2008 et décembre 2010. Les critères d’éligibilité étaient un âge supérieur à 16 ans, une épreuve histologique d'un sarcome des tissus mous à l'exclusion des tumeurs stromales gastro-intestinales (GIST). Les items recueillis étaient: épidémiologiques, cliniques, histologiques, Radiologiques, et thérapeutiques. Des analyses univariées puis multivariées ont été réalisées à la recherche de facteurs influençant la survie à 2 ans. Il s'agit de 33 cas, 17 Hommes et 16 Femmes, l’âge moyen était de 43,21 ans (Extrêmes= 18-76 ans). La tumeur était localisée aux extrémités dans 24 cas (72,72%). Le type histologique prédominant était le Liposarcome dans 9 cas (27,27%). Le stade tumoral était localisé dans 25 cas (75,8%), métastatique dans 8 cas (24,2%). Vingt-cinq tumeurs ont été traitées chirurgicalement dont 21 cas (84%) de chirurgie conservatrice et 4 cas (16%) de chirurgie radicale. La radiothérapie a été réalisée chez 10 patients (30,3%). La chimiothérapie a été faite chez 20 patients. En analyse univariée les facteurs pronostiques étaient l’âge (p=0,03) et le stade tumoral (p=0,09). L’âge et le stade tumoral sont des facteurs pronostiques influençant la survie des sarcomes des tissus mous. PMID:27022434

  2. Approche à l’endroit des blessures traumatiques à la main en soins primaires

    PubMed Central

    Cheung, Kevin; Hatchell, Alexandra; Thoma, Achilleas

    2013-01-01

    Résumé Objectif Passer en revue la prise en charge initiale des blessures traumatiques communes à la main que voient les médecins de soins primaires. Sources des données Nous avons examiné les données cliniques probantes et les ouvrages spécialisés récents cernés par des recherches dans la base de données électronique MEDLINE. Nous avons utilisé l’opinion d’experts pour compléter les recommandations dans les domaines où les données scientifiques étaient rares. Message principal Les médecins de soins primaires sont couramment appelés à prendre en charge des patients victimes de blessures traumatiques à la main. Dans le contexte d’un cas clinique, nous examinons l’évaluation, le diagnostic et la prise en charge initiale des traumatismes communs à la main. La présentation et la prise en charge des blessures au lit de l’ongle, des amputations de l’extrémité du doigt, des doigts en maillet, des fractures à la main, des lacérations de tendons, des morsures et de la ténosynovite infectieuse seront aussi discutées. Les principes de la prise en charge des blessures traumatiques à la main comportent la réduction et l’immobilisation des fractures, la prescription d’imagerie radiographique post-réduction, l’obtention d’un recouvrement par les tissus mous, la prévention et le traitement des infections et l’assurance d’une prophylaxie antitétanique. Conclusion Il est essentiel d’assurer une évaluation et une prise en charge appropriées des blessures traumatiques à la main pour prévenir une morbidité considérable à long terme dans une population autrement en santé. La reconnaissance sans délai des blessures qui nécessitent une demande de consultation urgente ou rapide auprès d’un chirurgien spécialiste de la main est également critique.

  3. Role of nitric oxide and cyclic GMP signaling in melanocyte response to hypergravity

    NASA Astrophysics Data System (ADS)

    Ivanova, Krassimira; Lambers, Britta; Tsiockas, Wasiliki; Block, Ingrid; Gerzer, Rupert

    Nitric oxide (NO) has a prominent role in many (patho)physiological processes in the skin including erythema, inflammation, and cancerogenesis. The soluble guanylyl cyclase (sGC), a key transducer in NO signaling, catalyzes the formation of the second messenger guanosine 3´,5´-cyclic monophosphate (cyclic cGMP or cGMP). For human melanocytes, which are responsible for skin pigmentation by synthesizing the pigment melanin, it has been reported that the NO/sGC/cGMP pathway is involved in UVB-induced melanogenesis. Melanin acts as a scavenger for free radicals that may arise during metabolic stress. It may also act as a photosensitizer that generates active oxygen species upon UV irradiation, which may initiate hypopigmentary disorders (e.g., vitiligo) as well as UV-induced oncogene cell transformation. In addition, melanoma, a deadly skin cancer, which arises from transformed melanocytes, is characterized by a resistance to chemotherapy. In our studies we have shown that NO can induce perturbation of melanocyte-extracellular matrix component interactions, which may contribute to loss of melanocytes or melanoma metastasis. Such NO effects appear to be modulated partly via cGMP. Moreover, we found that different guanylyl cyclase isoforms are responsible for cGMP synthesis in melanocytic cells. Normal human melanocytes and nonmetastatic melanoma cells predominantly express sGC, which appears to be associated with melanogenesis, whereas absence of NO-sensitive GC, but up-regulated activities of the natriuretic peptide-sensitive membrane guanylyl cyclase isoforms were found in highly metastatic phenotypes. Due to the growing interest in the regulation of signaling activities in normal and transformed cells under altered gravity conditions, we have further investigated whether the NO/cGMP signaling is involved in melanocyte response to gravitational stress. We found that normal human melanocytes and non-metastatic melanoma cell lines, but not highly metastatic cells

  4. LASP1, a Newly Identified Melanocytic Protein with a Possible Role in Melanin Release, but Not in Melanoma Progression

    PubMed Central

    Houben, Roland; Grunewald, Thomas G. P.; Goebeler, Matthias; Butt, Elke

    2015-01-01

    The LIM and SH3 protein 1 (LASP1) is a focal adhesion protein. Its expression is increased in many malignant tumors. However, little is known about the physiological role of the protein. In the present study, we investigated the expression and function of LASP1 in normal skin, melanocytic nevi and malignant melanoma. In normal skin, a distinct LASP1 expression is visible only in the basal epidermal layer while in nevi LASP1 protein is detected in all melanocytes. Melanoma exhibit no increase in LASP1 mRNA compared to normal skin. In melanocytes, the protein is bound to dynamin and mainly localized at late melanosomes along the edges and at the tips of the cell. Knockdown of LASP1 results in increased melanin concentration in the cells. Collectively, we identified LASP1 as a hitherto unknown protein in melanocytes and as novel partner of dynamin in the physiological process of membrane constriction and melanosome vesicle release. PMID:26061439

  5. Pigmentation PAX-ways: The role of Pax3 in melanogenesis, melanocyte stem cell maintenance, and disease

    PubMed Central

    Kubic, Jennifer D.; Young, Kacey P.; Plummer, Rebecca S.; Ludvik, Anton E.; Lang, Deborah

    2010-01-01

    Transcription factors initiate a program of gene expression and are catalysts in downstream molecular cascades that modulate a variety of cellular processes. Pax3 is a transcription factor that is important in the melanocyte and influences melanocytic proliferation, resistance to apoptosis, migration, lineage specificity and differentiation. In this review, we focus on Pax3 and the molecular pathways that Pax3 is a part of during melanogenesis and in the melanocyte stem cell. These roles of Pax3 are emphasized during the development of diseases and syndromes resulting from either too much or too little Pax3 function. Due to its key task in melanocyte stem cells and tumors, the Pax3 pathway may provide an ideal target for either stem cell or cancer therapies. PMID:18983540

  6. Appearance of New Vemurafenib-associated Melanocytic Nevi on Normal-appearing Skin

    PubMed Central

    Bedikian, Agop Y.; Kim, Kevin B.

    2013-01-01

    Background: Vemurafenib, a selective BRAF inhibitor that has antineoplastic activity in patients with unresectable or metastatic malignant melanoma whose tumor harbors a BRAF V600E mutation, has multiple drug-associated cutaneous adverse effects. Purpose: To provide a detailed and comprehensive review of reported changing or new pigmented lesions in oncology patients who have been treated with vemurafenib. Methods: The new appearance of melanocytic nevi on normal-appearing skin after initiating treatment with vemurafenib is described in two men with metastatic malignant melanoma whose tumors demonstrated a BRAF V600E mutation. Using the PubMed database, an extensive literature search was performed for the following topics: vermurafenib, nevus, nevi, melanoma, pigmented lesion, cutaneous, adverse effect, side effect. The results of the search were used to secure all reports of new or changing pigmented lesions after initiating treatment with vemurafenib. Results: Vemurafenib is associated with both changes in existing pigmented lesions (including involution, alteration of color and size, and progression to melanoma) and the onset of new melanocytic lesions—nevi (in 5 patients) and primary melanomas (in 2 patients). Visual examination, dermoscopic evaluation, and reflectance confocal microscopy have been used to document the changes in existing or new melanocytic lesions subsequent to initiating treatment with vermurafenib. Histopathology analysis has shown these lesions to usually be either dysplastic nevi or new primary melanomas. Conclusion: Vemurafenib-treated patients can develop new pigmented lesions (such as nevi) and/or morphological changes in their existing melanocytic lesions (such as involution, increase in size, or alternation of color). In addition, they can develop new primary malignant melanomas that either occur de novo on normal-appearing skin or develop in pre-existing melanocytic lesions. Therefore, total body skin examination should be

  7. Changes in the proliferation and differentiation of neonatal mouse pink-eyed dilution melanocytes in the presence of excess tyrosine.

    PubMed

    Hirobe, Tomohisa; Wakamatsu, Kazumasa; Ito, Shosuke

    2003-12-01

    Changes in the proliferation and differentiation of epidermal melanocytes derived from newborn mice wild-type at the pink-eyed dilution (p) locus (P/P) and from congenic mice mutant at that locus (p/p) were investigated in serum-free primary culture, with or without the addition of L-Tyr. Incubation with added L-Tyr inhibited the proliferation of P/P melanocytes in a concentration-dependent manner and inhibition was gradually augmented as the donor mice aged. In contrast, L-Tyr stimulated the proliferation of p/p melanoblasts-melanocytes derived from 0.5-day-old mice, but inhibited their proliferation when derived from 3.5- or 7.5-day-old mice. L-Tyr stimulated the differentiation of P/P melanocytes. However, almost all cells were undifferentiated melanoblasts in control cultures derived from 0.5-, 3.5- and 7.5-day-old p/p mice, but L-Tyr induced their differentiation as the age of the donor mice advanced. The content of the eumelanin marker, pyrrole-2,3,5-tricarboxylic acid as well as the pheomelanin marker, 4-amino-3-hydroxyphenylalanine in p/p melanocytes was greatly reduced compared with P/P melanocytes. However, the contents of eumelanin and its precursor, 5,6-dihydroxyindole-2-carboxylic acid, as well as the contents of pheomelanin and its precursor, 5-S-cysteinyldopa in culture media from p/p melanocytes were similar to those of P/P melanocytes at all ages tested. L-Tyr increased the content of eumelanin and pheomelanin two- to threefold in cultured cells and media derived from 0.5-, 3.5- and 7.5-day-old mice. These results suggest that the proliferation of p/p melanoblasts-melanocytes is stimulated by L-Tyr, and that the differentiation of melanocytes is induced by L-Tyr as the age of the donor mice advanced, although eumelanin and pheomelanin fail to accumulate in p/p melanocytes and are released from them at all ages of skin development. PMID:14629719

  8. Developpement des betons semi autoplacants a rheologie adaptee pour des infrastructures

    NASA Astrophysics Data System (ADS)

    Sotomayor Cruz, Cristian Daniel

    Au cours des dernières décennies, les infrastructures canadiennes et québécoises comportent plusieurs structures en béton armé présentant des problèmes de durabilité dus aux conditions climatiques sévères, à la mauvaise conception des structures, à la qualité des matériaux, aux types des bétons choisis, aux systèmes de construction ou à l'existence d'événements incontrôlables. En ce qui concerne le choix du béton pour la construction des infrastructures, une vaste gamme de béton divisée en deux principaux types peut être utilisée: le béton conventionnel vibré (BCV) et le béton autoplaçant (BAP). Dans le cas d'un BCV, la consolidation inadéquate par vibration a été un problème récurrent, occasionnant des dommages structuraux. Ceci a conduit à une réduction de la durabilité et à une augmentation du coût d'entretien et de réparation des infrastructures. Rien que l'utilisation d'un BAP a des avantages tels que l'élimination de la vibration, la réduction des coûts de main d'oeuvre et l'amélioration de la qualité des structures, néanmoins, le coût initial d'un BAP par rapport à un BCV ne permet pas encore de généraliser son utilisation dans l'industrie de la construction. Ce mémoire présente la conception d'une nouvelle gamme de béton semi-autoplaçant pour la construction des infrastructures (BSAP-I) exigeant une vibration minimale. Il s'agit de trouver un équilibre optimal entre la rhéologie et le coût initial du nouveau béton pour conférer une bonne performance structurale et économique aux structures. Le programme expérimental établi a premièrement permis d'évaluer la faisabilité d'utilisation des BSAP-I pour la mise en place des piliers d'une infrastructure de pont à Sherbrooke. En plus, l'utilisation d'un plan d'expériences a permis l'évaluation de trois paramètres de formulation sur les propriétés des mélanges de BSAP-I à l'état frais et durci. Finalement, l'évaluation de la performance des

  9. Analyse des facteurs prédictifs de malignité des goitres nodulaires : à propos de 500 cas

    PubMed Central

    Bouaity, Brahim; Darouassi, Youssef; Chihani, Mehdi; Touati, Mohamed Mliha; Ammar, Haddou

    2016-01-01

    Les nodules thyroïdiens sont très fréquents et moins de 10% d'entre eux sont malin. Ils posent un véritable problème diagnostique et thérapeutique surtout par rapport à leur nature bénigne ou maligne. L’étude de certains facteurs cliniques et paracliniques de présomption de malignité permet de bien codifier la stratégie thérapeutique. Le but de ce travail est d’étudier les facteurs prédictifs de malignité des goitres nodulaires et comparer nos résultats à ceux de la littérature. Il s'agit d'une étude rétrospective à propos de 500 cas de goitres nodulaires opérés au service d'Oto-rhino-laryngologie (ORL) et Chirurgie cervico-faciale (CCF) de l'hôpital militaire Avicenne de Marrakech entre 2006 et 2012. Le pourcentage de cancers a été de 6,8%. L’âge moyen de nos patients était de 46 ans, avec une sex-ratio de 5 (F/H). A la palpation cervicale; le caractère dure du nodule a été constaté dans 94,4% des cas de cancer, avec des limites irrégulières dans 64,70% des cas de cancer. Trois nodules étaient fixes et ils étaient tous malins. Les adénopathies cervicales ont été constatées chez 8 malades dont 7 présentaient des cancers. A l’échographie, 61,8% des nodules malins présentaient un aspect hypoéchogène, avec des contours flous dans 88,24% des cas. La vascularisation intra nodulaire était présente dans 35,3% de ces cas des cancers avec des microcalcifications chez 55,9% d'entre eux. Le halo hypoéchogene périnodulaire était incomplet dans 73,5% des cas de cancer. Nos patients étaient en euthyroïdie dans 84,6% des cas. Les facteurs prédictifs de malignité d'un goitre nodulaire, étaient donc dans notre étude d'abord cliniques: l’âge supérieur à 60 ans, la consistance dure du nodule, sa fixité, son caractère irrégulier et mal limité à la palpation, ainsi que la présence d'adénopathie(s) cervicale(s) à l'examen; et échographiques: le caractère hypoéchogène, les limites floues, la présence de

  10. msg1, a novel melanocyte-specific gene, encodes a nuclear protein and is associated with pigmentation.

    PubMed Central

    Shioda, T; Fenner, M H; Isselbacher, K J

    1996-01-01

    Messenger RNA transcripts of the highly pigmented murine melanoma B16-F1 cells were compared with those from their weakly pigmented derivative B16-F10 cells by differential display. A novel gene called msg1 (melanocyte-specific gene) was found to be expressed at high levels in B16-F1 cells but at low levels in B16-F10 cells. Expression of msg1 was undetectable in the amelanotic K1735 murine melanoma cells. The pigmented murine melanocyte cell line melan-a expressed msg1, as did pigmented primary cultures of murine and human melanocytes; however, seven amelanotic or very weakly pigmented human melanoma cell lines were negative. Transformation of murine melanocytes by transfection with v-Ha-ras or Ela was accompanied by depigmentation and led to complete loss of msg1 expression. The normal tissue distribution of msg1 mRNA transcripts in adult mice was confined to melanocytes and testis. Murine msg1 and human MSG1 genes encode a predicted protein of 27 kDa with 75% overall amino acid identity and 96% identity within the C-terminal acidic domain of 54 amino acids. This C-terminal domain was conserved with 76% amino acid identity in another protein product of a novel human gene, MRG1 (msg1-related gene), isolated from normal human melanocyte cDNA by 5'-rapid amplification of cDNA ends based on the homology to msg1. The msg1 protein was localized to the melanocyte nucleus by immunofluorescence cytochemistry. We conclude that msg1 encodes a nuclear protein, is melanocyte-specific, and appears to be lost in depigmented melanoma cells. Images Fig. 1 Fig. 2 Fig. 4 Fig. 5 Fig. 6 PMID:8901575

  11. Compatibilite deformationnelle des betons autoplacants pour des utilisations dans les reparations des infrastructures routieres

    NASA Astrophysics Data System (ADS)

    Ghezal, Aicha Fadela

    Concrete structures repairs in Civil Engineering by using a thin bonded overlay is common practice. However the repaired structures are often victim of premature deterioration of the new repair material due to the appearance of restrained shrinkage cracks. In this context, the main objective of this thesis is to identify, through the experimental program called Phase I the principal parameters that significantly influence the creep potential of the evaluated mixtures. Once these parameters identified, the experimental entitled Phase II is conducted under conditions simulating repairs, and emphasis was placed on restrained shrinkage using instrumented ring test. Article 1 summarized the laboratory investigation undertaken to evaluate the potential of flexural creep behavior of several SCC. The results show clearly that the flexural creep potential of SCC varies widely depending on the nature of HRWR in use. In general, the use of naphthalene sulfonate leads to higher creep by comparison to polycarboxylate. It has been shown also that even when belonging to the same A.S.T.M. classification (polycarboxylic family) the magnitude of flexural creep varies also widely depending on the properties of polycarboxylic chemicals admixture. Based on the identified parameters in phase I, namely PNS superplasticizers type and PC2, with two ternary blended cements with fly ash (BTCFA) and slag (BTCS), the second experimental program was undertaken and summarized in articles 2 and 3. As presented in article 2, the results indicate that optimized SCCs produced with blended ternary cement with fly ash (BTCFA) developed at earlier age lower compressive and splitting-tensile strengths than the corresponding SCCs with blended cement with slag (BTCS). Test results also indicated that the drying shrinkage of SCCs based on BTCFA is higher than the corresponding SCCs proportioned with BTCS and attributed in part to higher total pores volume measured at 120 days on SCC BTCFA. The restrained shrinkage of SCC summarized in article 3 show that the resistance of SCC to shrinkage cracks was quite different depending on the nature of HRWR and the binder type in use. The cracking age increases in mixtures proportioned with PC-HRWR comparatively to PNS-HRWR. The SCC mixtures based on blended ternary cement containing Class F fly ash show shorter cracking age than the corresponding SCCs proportioned with ternary blended cement containing slag. Moreover, a data analysis of current research shows that the ratio of tensile strength to free shrinkage and modulus of elasticity, referred as index of dimensional compatibility, is a promising assessment of cracking resistant performance. In this way, only the free shrinkage test (ASTM C157) and basic mechanical properties are required to assess cracking of candidate concrete mixture designs.

  12. Effets Seebeck et Nernst dans les cuprates: Etude de la reconstruction de la surface de Fermi sous champ magnetique intense

    NASA Astrophysics Data System (ADS)

    Laliberte, Francis

    2010-06-01

    Ce memoire presente des mesures de transport thermoelectrique, les effets Seebeck et Nernst, dans une serie d'echantillons de supraconducteurs a haute temperature critique. Des resultats obtenus recemment au Laboratoire National des Champs Magnetiques Intenses a Grenoble sur La1.7Eu0.2Sr0.1 CuO4, La1.675Eu0.2Sr0.125CuO 4, La1.64Eu0.2Sr0.16CuO4, La1.74Eu0.1Sr0.16CuO4 et La 1.4Nd0.4Sr0.2CuO4 sont analyses. Une attention particuliere est accordee aux equations de la theorie semi-classique du transport et leur validite est verifiee. La procedure experimentale et les materiaux utilises pour concevoir les montages de mesures sont expliques en detail. Enfin, un chapitre est dedie a l'explication et l'interpretation des resultats de transport thermoelectrique sur YBa2Cu3O6+delta publies au cours de l'hiver 2010 dans les revues Nature et Physical Review Letters. Les donnees d'effet Seebeck dans les echantillons de La 1.8-x,Eu0.2SrxCuO 4, ou un changement de signe est observe, permettent de conclure a la presence d'une poche d'electrons dans la surface de Fermi qui domine le transport a basse temperature dans la region sous-dopee du diagramme de phase. Cette conclusion est similaire a celle obtenue par des mesures d'effet Hall dans YBa 2Cu3O6+delta et elle cadre bien dans un scenario de reconstruction de la surface de Fermi. Les donnees d'effet Nernst recueillies indiquent que la contribution des fluctuations supraconductrices est limitee a un modeste intervalle de temperature au-dessus de la temperature critique.

  13. Neural crest and Schwann cell progenitor-derived melanocytes are two spatially segregated populations similarly regulated by Foxd3

    PubMed Central

    Nitzan, Erez; Pfaltzgraff, Elise R.; Labosky, Patricia A.; Kalcheim, Chaya

    2013-01-01

    Skin melanocytes arise from two sources: either directly from neural crest progenitors or indirectly from neural crest-derived Schwann cell precursors after colonization of peripheral nerves. The relationship between these two melanocyte populations and the factors controlling their specification remains poorly understood. Direct lineage tracing reveals that neural crest and Schwann cell progenitor-derived melanocytes are differentially restricted to the epaxial and hypaxial body domains, respectively. Furthermore, although both populations are initially part of the Foxd3 lineage, hypaxial melanocytes lose Foxd3 at late stages upon separation from the nerve, whereas we recently found that epaxial melanocytes segregate earlier from Foxd3-positive neural progenitors while still residing in the dorsal neural tube. Gain- and loss-of-function experiments in avians and mice, respectively, reveal that Foxd3 is both sufficient and necessary for regulating the balance between melanocyte and Schwann cell development. In addition, Foxd3 is also sufficient to regulate the switch between neuronal and glial fates in sensory ganglia. Together, we propose that differential fate acquisition of neural crest-derived cells depends on their progressive segregation from the Foxd3-positive lineage. PMID:23858437

  14. Melanocyte response to gravitational stress: an overview with a focus on the role of cyclic nucleotides

    NASA Astrophysics Data System (ADS)

    Ivanova, Krassimira; Tsiockas, Wasiliki; Eiermann, Peter; Hauslage, Jens; Hemmersbach, Ruth; Block, Ingrid; Gerzer, Rupert

    Human melanocytes are responsible for skin pigmentation by synthesizing the pigment melanin. A well known modulator of melanogenesis is the second messenger adenosine 3',5'-cyclic monophos-phate (cAMP). It has also been reported that the nitric oxide (NO)/soluble guanylyl cyclase (sGC)/guanosine 3',5'-cyclic monophosphate (cGMP) pathway is involved in UVB-induced melanogenesis. Melanin acts as a scavenger for free radicals during oxidative stress, but it may additionally act as a photosensitizer that generates active oxygen species upon UV radiation, which may initiate hypopigmentary disorders (e.g., vitiligo) as well as UV-induced oncogene cell transformation. Melanoma, a deadly skin cancer which arises from transformed melanocytes, is characterized by a resistance to chemotherapy. In our studies we were able to show that hu-man melanocytic cells differentially respond to gravitational stress. Hypergravity (up to 5 g for 24 h) stimulated cGMP efflux in cultured human melanocytes and non-metastatic melanoma cells, but not in metastatic phenotypes under the conditions of limited degradation [e.g., in the presence of phosphodiesterase (PDE) inhibitors] or stimulated synthesis of cGMP [e.g., by NO donors, but not natriuretic peptides], whereas cellular proliferation and morphology were not altered. Interestingly, long-term exposure to hypergravity stimulated an increase in both intra-cellular as well as extracellular cAMP levels as well as melanogenesis in pigmented melanocytes and non-metastatic melanoma cells. As some cAMP-PDEs are regulated by cGMP, it seems that the hypergravity-induced alteration of melanocyte pigmentation could be a result of a cross-talk between these two cyclic nucleotides. Hypergravity induced further an increase in the mRNA and protein levels of the selective cGMP and cAMP exporters, the multidrug resistance proteins (MRP) 4 and 5 -but not 8 -, whereas simulated microgravity (up to 1.21x10-2 g for 24 h) -provided by a fast-rotating clinostat

  15. S-100 protein in soft-tissue tumors derived from Schwann cells and melanocytes.

    PubMed Central

    Stefansson, K.; Wollmann, R.; Jerkovic, M.

    1982-01-01

    In soft tissues outside the central nervous system, S-100 protein is found normally only in Schwann cells. Using the peroxidase-antiperoxidase immunohistochemical method S-100 was also found in tumors derived from Schwann cells and melanocytes, including neurofibromas, neurilemomas, granular cell myoblastomas, cutaneous nevi, and malignant melanomas. S-100 was not detected in malignant Schwannomas, neuroblastomas, oat cell carcinomas, medullary carcinomas of the thyroid, paragangliomas, or meningiomas. S-100 was also absent from neoplasms of soft tissues not usually considered to arise from cells of neural crest origin. S-100 appears to be a useful marker for identifying neoplasms derived from Schwann cells and melanocytes. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 PMID:6278936

  16. THE MOLECULAR PATHOLOGY OF MELANOMA: AN INTEGRATED TAXONOMY OF MELANOCYTIC NEOPLASIA

    PubMed Central

    Bastian, Boris C.

    2016-01-01

    Melanomas are comprised of multiple biologically distinct categories, which differ in cell of origin, age of onset, clinical and histologic presentation, pattern of metastasis, ethnic distribution, causative role of UV radiation, predisposing germ line alterations, mutational processes, and patterns of somatic mutations. Neoplasms are initiated by gain of function mutations in one of several primary oncogenes, typically leading to benign melanocytic nevi with characteristic histologic features. The progression of nevi is restrained by multiple tumor suppressive mechanisms. Secondary genetic alterations override these barriers and promote intermediate or overtly malignant tumors along distinct progression trajectories. The current knowledge about pathogenesis, clinical, histological and genetic features of primary melanocytic neoplasms is reviewed and integrated into a taxonomic framework. PMID:24460190

  17. TBX2 expression is regulated by PAX3 in the melanocyte lineage

    PubMed Central

    Liu, Fang; Cao, Juxiang; Lv, Jinghu; Dong, Liang; Pier, Eric; Xu, George X.; Wang, Rui-an; Xu, Zhixiang; Goding, Colin; Cui, Rutao

    2012-01-01

    The paired box homeotic gene 3 (PAX3) is a crucial regulator for the maintenance of melanocytic progenitor cells and has a poorly defined role in melanoma. To understand how PAX3 affects melanocyte and melanoma proliferation, we identified potential PAX3 downstream targets through gene expression profiling. Here we identify TBX2, a key developmental regulator of cell identity and an anti-senescence factor in melanoma, as a directly regulated PAX3 target. We also found that TBX2 is involved in the survival of melanoma cells, and is overexpressed in some melanoma specimens. The identification of TBX2 as a target for PAX3 provides a key insight into how PAX3 may contribute to melanoma evolution and may provide opportunities for pro-senescence therapeutic intervention aimed at disrupting the ability of PAX3 to regulate TBX2. PMID:23020925

  18. Resolution of vitiligo following excision of halo congenital melanocytic nevus: a rare case report.

    PubMed

    Wang, Kai; Wang, Zhi; Huang, Weiqing

    2016-05-01

    Halo congenital melanocytic nevus (CMN) associated with vitiligo is rare, especially with regard to CMN excision. Only two reports of excision of halo CMN following repigmentation of vitiligo are found in the literature. We present a case of a girl with halo CMN and periorbital vitiligo. The halo CMN was excised and followed by spontaneous improvement of vitiligo. The result suggests excision of the inciting lesion may be a promising way to control vitiligo. PMID:26627472

  19. Reliability and inter-observer agreement of dermoscopic diagnosis of melanoma and melanocytic naevi. Dermoscopy Panel.

    PubMed

    Carli, P; De Giorgi, V; Naldi, L; Dosi, G

    1998-10-01

    The aim of this study was to analyse the reliability and the inter-observer agreement of dermoscopy in the diagnosis of melanocytic skin lesions. Nine dermatologists, with a different training experience and who routinely used dermoscopy in different hospitals in Italy, evaluated clinical and dermoscopy photographs of 15 melanocytic lesions (four invasive melanomas, four histologically common naevi, and seven naevi with histological atypia). A further series of dermoscopic photographs of 40 melanocytic lesions was evaluated to quantify inter-observer concordance in recognizing dermoscopic criteria. Compared to the true (histological) diagnosis, clinical diagnosis (categories: melanoma, common naevus, atypical naevus) was correct in 40% of cases (range, 27-53%). The percentage raised to 55% (40-73%) by the use of dermoscopy, with an average improvement of 15.6%. Concerning melanoma, clinical diagnosis resulted in a sensitivity of 41.9%, specificity of 77.8%, positive predictive value (PPV) of 36.1%, negative predictive value (NPV) of 81.8%. By using dermoscopy, an improvement of diagnostic performance was found (sensitivity 75%, specificity 88.8%, VPP 71.0%, VPN 90.7%). The inter-observer agreement in melanoma diagnosis, by using dermoscopy, was similar to that obtained by clinical examination (k statistics = 0.54 and 0.52, respectively). Concerning dermoscopic criteria, the best agreement among observers was found for pseudopods, a dermoscopic parameter related to the radial growth phase of melanoma. We conclude that dermoscopy is an useful tool for a non-invasive diagnosis of melanocytic skin lesions, improving the diagnostic performance compared to clinical examination. PMID:9884886

  20. Limbal melanocytes support limbal epithelial stem cells in 2D and 3D microenvironments.

    PubMed

    Dziasko, Marc A; Tuft, Stephen J; Daniels, Julie T

    2015-09-01

    Human limbal epithelial stem cells (LESCs) are essential for the maintenance of the corneal epithelium of the ocular surface. LESCs are located within limbal crypts between the palisades of Vogt in the limbus; the interface between the peripheral cornea and conjunctiva. The limbal crypts have been proposed as a LESC niche owing to their support of epithelial cells, which can form holoclone colonies in vitro. Closely associated with the limbal crypts is a concentrated population of melanocytes. The anatomical location and close proximity to putative LESC suggests that melanocytes might play a role in maintenance of these stem cells in the niche. The aim of this study was to assess the ability of human limbal melanocytes (hLM) to support the expansion of human limbal epithelial cells (LECs) in vitro as an indicator of functional cell-cell interaction. After observing that hLM co-localize with clusters of compact epithelial cells in the native limbal crypts, hLM were isolated from crypt-rich cadaveric limbal biopsies and used as feeders for the culture of LECs. Interestingly, LECs grown on mitotically active hLM were able to generate large epithelial colonies that contained small and compact cells with morphological stem cell characteristics. Immunocytochemistry revealed that LECs expanded on hLM were positive for the expression of the putative stem cell markers CK15, Bmi-1 and p63α and negative for the marker of terminal cell differentiation CK3. LECs and hLM were finally co-cultured on RAFT (real architecture for 3D tissue) collagen tissue equivalents. In 3D co-cultures, hLM promoted multi-layering of the epithelial sheet in which basal cells were maintained in an undifferentiated state. Taken together, these observations suggest melanocytes could play an important role in the maintenance of LESCs in the native human limbal stem cell niche. PMID:26142953

  1. Presence of T cells and macrophages in inflammatory vitiligo skin parallels melanocyte disappearance.

    PubMed Central

    Le Poole, I. C.; van den Wijngaard, R. M.; Westerhof, W.; Das, P. K.

    1996-01-01

    Evidence for the involvement of cellular immunity in the etiopathogenesis of the hypopigmentary disorder vitiligo is provided by rare cases of inflammatory vitiligo. Nonlesional, perilesional, and lesional skin biopsies from three inflammatory vitiligo patients were immunohistochemically analyzed. The composition of inflammatory infiltrates present in perilesional skin was analyzed by antibodies to T cells (CD2, CD3, CD4, and CD8), Langerhans cells (CD1a), and macrophages (CD36 and CD68). The presence of activation markers on inflammatory cells was evaluated by analysis of HLA-DR, interleukin-2 receptor, and HECA452 expression. The presence or absence of melanocytes was determined by the antibody NKI-beteb. Moreover, the abundance of matrix molecule tenascin was semi-quantified using T2H5. Results indicate that within perilesional skin, epidermis-infiltrating T cells exhibit an increased CD8/CD4 ratio and increased cutaneous lymphocyte antigen and interleukin-2 receptor expression. These cells are frequently juxtapositionally apposed to remaining melanocytes. In perilesional dermis, CD68+OKM5- macrophages were more numerous than in lesional or nonlesional skin. Keratinocytes as well as melanocytes consistently express major histocompatibility complex class II antigens along stretches of basal and suprabasal layers in perilesional epidermis. Moreover, inflammation is accompanied by increased tenascin content. Although these observations do not permit differentiation between the immune infiltrates being a result as opposed to the cause of the disease process, results presented in this study are very suggestive of involvement of local immune reactivity in melanocyte destruction. Images Figure 1 Figure 4 Figure 8 Figure 9 PMID:8644862

  2. Douleurs et conflits : Approche comparative et implications pour la qualité des soins en fin de vie

    PubMed Central

    Mpinga, Emmanuel Kabengele; Verloo, Henk; Rapin, Charles-Henri; Chastonay, Philippe

    2009-01-01

    Le conflit serait-il à l’organisation ce que la douleur est à un organisme ? OBJECTIFS: Explorer les similitudes et les differences entre les douleurs et les conflits dans les contextes de soins de fin de vie. Mieux comprendre le rôle des conflits dans la qualité de ces soins. MÉTHODOLOGIE: Méthode comparative et réflexive autour des politiques de prise en charge des douleurs et des conflits dans les systèmes de soins. RÉSULTATS: Les conflits et les douleurs présentent de nombreuses similitudes de par leur identité, leur typologie, leur prévalence, leur fonction d’alerte, leurs coûts économiques et sociaux, le déni ou l’occultation qui les entourent et les obstacles à leur prise en charge adéquate. À l’inverse, des différences apparaissent dans la prise en charge des douleurs comparée à celle des conflits. Ces différences portent sur l’existence des programmes de prévention et de lutte sur les scènes nationale et internationale, la mise en œuvre des activités de recherche et de formation et la visibilité sociale. Pour les conflits, cette mise en œuvre n’existe pas encore. CONCLUSION: Les décideurs en clinique et en santé publique devraient intégrer les conflits comme un indicateur de la qualité des soins et élaborer des politiques pertinentes en matière de santé. PMID:19714268

  3. Formation et Evolution des Quasars et Contraintes cosmologiques

    NASA Astrophysics Data System (ADS)

    Hatziminaoglou, Evanthia

    2000-06-01

    Cette thèse porte sur l'étude de l'évolution des quasars. Elle en aborde certains aspects théoriques et observationnels, ainsi que la construction des grands échantillons de quasars dans le but à long terme de combiner le tout dans un test cosmologique géométrique pour déterminer les valeurs des paramètres cosmologiques Omega et Lambda. Les paramètres cosmologiques Omegaspan>et Lambdaspan>décrivent la géométrie globale de l'Univers. En faisant des hypothèses raisonnables sur la distribution spatiale et l'évolution des objets astrophysiques (galaxies, amas des galaxies, quasars), on peut déterminer les valeurs de ces paramètres qui sont cohérentes avec ces hypothèses. Les tests cosmologiques traditionnels ont besoin de ''chandelles standards'', objets dont les propriétés intrinsèques sont indépendantes des distances. De tels objets sont probablement fictifs. Néanmoins, certains de ces tests cosmologiques peuvent être adaptés si l'évolution individuelle, ou au moins l'évolution statistique d'une population d'objets est connue. La question de la nature de l'évolution des quasars a très vite été posée et des réponses ''phénoménologiques'' ont d'abord été données. Ces réponses ne faisaient que donner une forme mathématique à l'évolution mais n'expliquaient rien de la physique duphénomène. Les premières tentatives de construction d'un modèle physique, liées au processus d'accrétion sur un trou noir et à la théorie de la formation de l'Univers ont commencé à la fin des années 80. Depuis, des dizaines de modèles tentent d'expliquer les observations, qui sont les résultats de l'étude d'objets de plus en plus nombreux. Au cours de cette thèse, le test V/Vmax a été appliqué sur l'échantillon du Large Bright Quasar Survey en montrant 1) que l'échantillon était biaisé à cause des critères de sélection et 2) que la (simple) loi de Pure Evolution en Luminosité n'était pas une bonne approximation à tout

  4. Rhododendrol, a depigmentation-inducing phenolic compound, exerts melanocyte cytotoxicity via a tyrosinase-dependent mechanism.

    PubMed

    Sasaki, Minoru; Kondo, Masatoshi; Sato, Kohji; Umeda, Mai; Kawabata, Keigo; Takahashi, Yoshito; Suzuki, Tamio; Matsunaga, Kayoko; Inoue, Shintaro

    2014-09-01

    Rhododendrol, an inhibitor of melanin synthesis developed for lightening/whitening cosmetics, was recently reported to induce a depigmentary disorder principally at the sites of repeated chemical contact. Rhododendrol competitively inhibited mushroom tyrosinase and served as a good substrate, while it also showed cytotoxicity against cultured human melanocytes at high concentrations sufficient for inhibiting tyrosinase. The cytotoxicity was abolished by phenylthiourea, a chelator of the copper ions at the active site, and by specific knockdown of tyrosinase with siRNA. Hence, the cytotoxicity appeared to be triggered by the enzymatic conversion of rhododendrol to active product(s). No reactive oxygen species were detected in the treated melanocytes, but up-regulation of the CCAAT-enhancer-binding protein homologous protein gene responsible for apoptosis and/or autophagy and caspase-3 activation were found to be tyrosinase dependent. These results suggest that a tyrosinase-dependent accumulation of ER stress and/or activation of the apoptotic pathway may contribute to the melanocyte cytotoxicity. PMID:24890809

  5. A Murine Model for the Development of Melanocytic Nevi and their Progression to Melanoma

    PubMed Central

    Nasti, Tahseen H.; Cochran, J. Barry; Tsuruta, Yuko; Yusuf, Nabiha; McKay, Kristopher M.; Athar, Mohammad; Timares, Laura; Elmets, Craig A.

    2015-01-01

    Acquired melanocytic nevi are commonly found in sun exposed and unexposed human skin, but the potential for their transformation into invasive melanoma is not clear. Therefore, a mouse model of nevus initiation and progression was developed in C3H/HeN mice using a modified chemical carcinogenesis protocol. Nevi develop due to DNA damage initiated by dimethylbenz(a)anthracene (DMBA), and followed by chronic promotion with 12-O-tetradecanoyl-phorbol-13-acetate (TPA). Dysplastic pigmented skin lesions appeared in 7-9 weeks with 100% penetrance. Nests of melanocytic cells appeared in a subset of skin draining lymph nodes (dLN) by 25 weeks, but not in age matched controls. Immunohistochemistry, real-time PCR and flow cytometric analyses confirmed their melanocytic origin. Transformed cells were present in a subset of nevi and dLNs, which exhibited anchorage-independent growth, tumor development, and metastasis in nude mice. Approximately 50% of the cell lines contained H-ras mutations and lost tumor suppressor p16Ink4a expression. While most studies of melanoma focus on tumor progression in transgenic mouse models where the mutations are present from birth, our model permits investigation of acquired mutations at the earliest stages of nevus initiation and promotion of nevus cell transformation. This robust nevus/melanoma model may prove useful for identifying genetic loci associated with nevus formation, novel oncogenic pathways, tumor targets for immune-prevention, screening therapeutics, and elucidating mechanisms of immune surveillance and immune evasion. PMID:25788145

  6. The effect of melanin bleaching on immunohistochemical staining in heavily pigmented melanocytic neoplasms.

    PubMed

    Orchard, G E; Calonje, E

    1998-08-01

    The accumulation of excessive amounts of melanin in melanocytic lesions can obscure cellular morphology and can further hinder immunocytochemical procedures. We have used a modification of the potassium permanganate/oxalic acid melanin-bleaching technique, involving much reduced bleaching times, in order to remove melanin granules prior to incubation with primary antibody. We have assessed a panel of antibodies applicable to the evaluation of melanocytic lesions and in addition have also assessed antibodies that may be more useful in research. The study attempts to determine which antigens may be affected by bleaching and which are not. Antigens S100, HMB 45, NKIC3, CD34, and L26 are relatively unaffected by this procedure. Factor-VIII-related antigen and vimentin and CD68 antigens produced enhanced staining. In contrast, antigens CD3, CD31, and CD45RO were abolished. In addition, smooth muscle actin and desmin antigens demonstrated considerable nonspecific background staining and were not reliable in this study. This technique demonstrates that a fairly wide range of antigens are preserved after bleaching and that distinction between melanocytes and melanophages can reliably be performed using the conventional immunocytochemical chromogen 3,3-diaminobenzidine and without the need for elaborate counterstaining. PMID:9700373

  7. Pharmacologic suppression of MITF expression via HDAC inhibitors in the melanocyte lineage

    PubMed Central

    Yokoyama, Satoru; Feige, Erez; Poling, Laura L.; Levy, Carmit; Widlund, Hans R.; Khaled, Mehdi; Kung, Andrew L.; Fisher, David E.

    2013-01-01

    Summary Melanoma incidence continues to rise at an alarming rate while effective systemic therapies remain very limited. Microphthalmia-associated transcription factor (MITF) is required for development of melanocytes and is an amplified oncogene in a fraction of human melanomas. MITF also plays an oncogenic role in human clear cell sarcomas, which typically exhibit melanoma-like features. Although pharmacologic suppression of MITF is of potential interest in a variety of clinical settings, it is not known to contain intrinsic catalytic activity capable of direct small molecule inhibition. An alternative drug-targeting strategy is to identify and interfere with lineage-restricted mechanisms required for its expression. Here, we report that multiple HDAC-inhibitor drugs potently suppress MITF expression in melanocytes, melanoma and clear cell sarcoma cells. Although HDAC inhibitors may affect numerous cellular targets, we observed suppression of skin pigmentation by topical drug application as well as evidence of anti-melanoma efficacy in vitro and in mouse xenografts. Consequently, HDAC inhibitor drugs are candidates to play therapeutic roles in targeting conditions affecting the melanocyte lineage. PMID:18627530

  8. The Effect of Otic Melanocyte Destruction on Auditory and Vestibular Function: a Study on Vitiligo Patients.

    PubMed

    Mahdi, Parvane; Amali, Amin; Ruzbahani, Masoumeh; Pourbakht, Akram; Mahdavi, Asadollah

    2016-02-01

    The hallmark of vitiligo is the disappearance of melanocytes from the skin. As a result, of melanocytes presence in the auditory and vestibular apparatus, the involvement of these systems in vitiligo which targets the melanocytes of the whole body is possible; suggesting that vitiligo is a systemic disease rather than a purely cutaneous problem. A total of 21 patients with vitiligo were enrolled in this study. A group of 20 healthy subjects served as a control group. Pure tone audiometry (PTA), auditory brainstem responses (ABR) and vestibular evoked myogenic potentials (VEMP) were carried out in all participants. High frequency sensory neural hearing loss was seen in 8 (38.09%) patients. ABR analysis revealed 10 (47.61%) had an abnormal increase in latency of wave III, and 6 (28.57%) had an abnormal prolongation of IPL I-III, however, regarding our VEMP findings, there were no recorded responses on left ear of 1 (4.76%) patient and latency of p13 was prolonged in 5(23.80%) patients. There was no correlation between ages, duration of disease, and any of the recorded parameters (P>0.05). In the present survey, we highlighted the auditory and vestibular involvement in vitiligo patients. PMID:26997595

  9. A melanocyte--melanoma precursor niche in sweat glands of volar skin.

    PubMed

    Okamoto, Natsuko; Aoto, Takahiro; Uhara, Hisashi; Yamazaki, Satoshi; Akutsu, Hidenori; Umezawa, Akihiro; Nakauchi, Hiromitsu; Miyachi, Yoshiki; Saida, Toshiaki; Nishimura, Emi K

    2014-11-01

    Determination of the niche for early-stage cancer remains a challenging issue. Melanoma is an aggressive cancer of the melanocyte lineage. Early melanoma cells are often found in the epidermis around sweat ducts of human volar skin, and the skin pigmentation pattern is an early diagnostic sign of acral melanoma. However, the niche for melanoma precursors has not been determined yet. Here, we report that the secretory portion (SP) of eccrine sweat glands provide an anatomical niche for melanocyte-melanoma precursor cells. Using lineage-tagged H2B-GFP reporter mice, we found that melanoblasts that colonize sweat glands during development are maintained in an immature, slow-cycling state but renew themselves in response to genomic stress and provide their differentiating progeny to the epidermis. FISH analysis of human acral melanoma expanding in the epidermis revealed that unpigmented melanoblasts with significant cyclin D1 gene amplification reside deep in the SP of particular sweat gland(s). These findings indicate that sweat glands maintain melanocyte-melanoma precursors in an immature state in the niche and explain the preferential distribution of early melanoma cells around sweat glands in human volar skin. PMID:25065272

  10. Serotonergic regulation of melanocyte conversion: A bioelectrically regulated network for stochastic all-or-none hyperpigmentation.

    PubMed

    Lobikin, Maria; Lobo, Daniel; Blackiston, Douglas J; Martyniuk, Christopher J; Tkachenko, Elizabeth; Levin, Michael

    2015-10-01

    Experimentally induced depolarization of resting membrane potential in "instructor cells" in Xenopus laevis embryos causes hyperpigmentation in an all-or-none fashion in some tadpoles due to excess proliferation and migration of melanocytes. We showed that this stochastic process involved serotonin signaling, adenosine 3',5'-monophosphate (cAMP), and the transcription factors cAMP response element-binding protein (CREB), Sox10, and Slug. Transcriptional microarray analysis of embryos taken at stage 15 (early neurula) and stage 45 (free-swimming tadpole) revealed changes in the abundance of 45 and 517 transcripts, respectively, between control embryos and embryos exposed to the instructor cell-depolarizing agent ivermectin. Bioinformatic analysis revealed that the human homologs of some of the differentially regulated genes were associated with cancer, consistent with the induced arborization and invasive behavior of converted melanocytes. We identified a physiological circuit that uses serotonergic signaling between instructor cells, melanotrope cells of the pituitary, and melanocytes to control the proliferation, cell shape, and migration properties of the pigment cell pool. To understand the stochasticity and properties of this multiscale signaling system, we applied a computational machine-learning method that iteratively explored network models to reverse-engineer a stochastic dynamic model that recapitulated the frequency of the all-or-none hyperpigmentation phenotype produced in response to various pharmacological and molecular genetic manipulations. This computational approach may provide insight into stochastic cellular decision-making that occurs during normal development and pathological conditions, such as cancer. PMID:26443706

  11. The epidermal melanocyte population in the skin of ultraviolet-irradiated crested newt

    SciTech Connect

    Losa, M.; Zavanella, T.; Milani, S.

    1982-02-01

    The response of the epidermal melanocyte population to repeated ultraviolet (UV) exposure (wavelength spectrum 275-350 nm) has been investigated in the crested newt, Triturus cristatus carnifex. The effects of different doses of UV light were studied. The animals were killed 7 months after the first UV exposure. Only a slight decrease in the number of pigment cells was found after 85 sequential irradiations with a total dose of 1.3 x 10(5) J/m2, whereas striking decreases were observed when the same total dose was fractionated into 14 exposures or when a double dose was given in 57 exposures. The relationship between the square roots of the epidermal melanocyte densities and single doses appeared to be roughly linear, at least over the range of doses administered. The main factor in melanocyte damage seemed to be the single dose of irradiation rather than the cumulative dose administered. Decreased melanin content of the keratinocytes was observed in most irradiated animals.

  12. Premature Graying as a Consequence of Compromised Antioxidant Activity in Hair Bulb Melanocytes and Their Precursors

    PubMed Central

    Shi, Ying; Luo, Long-Fei; Liu, Xiao-Ming; Zhou, Qiong; Xu, Shi-Zheng; Lei, Tie-Chi

    2014-01-01

    Intricate coordinated mechanisms that govern the synchrony of hair growth and melanin synthesis remain largely unclear. These two events can be uncoupled in prematurely gray hair, probably due to oxidative insults that lead to the death of oxidative stress-sensitive melanocytes. In this study, we examined the gene expression profiles of middle (bulge) and lower (hair bulb) segments that had been micro-dissected from unpigmented and from normally pigmented hair follicles from the same donors using quantitative real-time RT-PCR (qPCR) arrays. We found a significant down-regulation of melanogenesis-related genes (TYR, TYRP1, MITF, PAX3, POMC) in unpigmented hair bulbs and of marker genes typical for melanocyte precursor cells (PAX3, SOX10, DCT) in unpigmented mid-segments compared with their pigmented analogues. qPCR, western blotting and spin trapping assays revealed that catalase protein expression and hydroxyl radical scavenging activities are strongly repressed in unpigmented hair follicles. These data provide the first clear evidence that compromised antioxidant activity in gray hair follicles simultaneously affects mature hair bulb melanocytes and their immature precursor cells in the bulge region. PMID:24695442

  13. Infrared A radiation promotes survival of human melanocytes carrying ultraviolet radiation-induced DNA damage.

    PubMed

    Kimeswenger, Susanne; Schwarz, Agatha; Födinger, Dagmar; Müller, Susanne; Pehamberger, Hubert; Schwarz, Thomas; Jantschitsch, Christian

    2016-06-01

    The link between solar radiation and melanoma is still elusive. Although infrared radiation (IR) accounts for over 50% of terrestrial solar energy, its influence on human skin is not well explored. There is increasing evidence that IR influences the expression patterns of several molecules independently of heat. A previous in vivo study revealed that pretreatment with IR might promote the development of UVR-induced non-epithelial skin cancer and possibly of melanoma in mice. To expand on this, the aim of the present study was to evaluate the impact of IR on UVR-induced apoptosis and DNA repair in normal human epidermal melanocytes. The balance between these two effects is a key factor of malignant transformation. Human melanocytes were exposed to physiologic doses of IR and UVR. Compared to cells irradiated with UVR only, simultaneous exposure to IR significantly reduced the apoptotic rate. However, IR did not influence the repair of UVR-induced DNA damage. IR partly reversed the pro-apoptotic effects of UVR via modification of the expression and activity of proteins mainly of the extrinsic apoptotic pathway. In conclusion, IR enhances the survival of melanocytes carrying UVR-induced DNA damage and thereby might contribute to melanomagenesis. PMID:26844814

  14. Mechanical properties of growing melanocytic nevi and the progression to melanoma

    NASA Astrophysics Data System (ADS)

    Taloni, Alessandro; Alemi, Alexander; Ciusani, Emilio; Sethna, James P.; Zapperi, Stefano; La Porta, Caterina A. M.; National Research Council Of Italy Team; Lassp, Department Of Physics, Cornell University Team; Istituto Neurologico Carlo Besta Collaboration; Department Of Biosciences, University Of Milano Team

    2015-03-01

    Melanocytic nevi are benign proliferations that sometimes turn into malignant melanoma in a way that is still unclear from the biochemical and genetic point of view. Diagnostic and prognostic tools are then mostly based on dermoscopic examination and morphological analysis of histological tissues. To investigate the role of mechanics and geometry in the morpholgical dynamics of melanocytic nevi, we present a computational model for cell proliferation in a layered non-linear elastic tissue. Our simulations show that the morphology of the nevus is correlated to the initial location of the proliferating cell starting the growth process and to the mechanical properties of the tissue. We also demonstrate that melanocytes are subject to compressive stresses that fluctuate widely in the nevus and depend on the growth stage. Numerical simulations of cells in the epidermis releasing matrix metalloproteinases display an accelerated invasion of the dermis by destroying the basal membrane. Moreover, we show experimentally that osmotic stress and collagen inhibit growth in primary melanoma cells while the effect is much weaker in metastatic cells.

  15. UVB-irradiated keratinocytes induce melanoma-associated ganglioside GD3 synthase gene in melanocytes via secretion of tumor necrosis factor α and interleukin 6

    SciTech Connect

    Miyata, Maiko; Ichihara, Masatoshi; Tajima, Orie; Sobue, Sayaka; Kambe, Mariko; Sugiura, Kazumitsu; Furukawa, Koichi; Furukawa, Keiko

    2014-03-07

    Highlights: • Melanocytes showed low ST8SIA1 and high B3GALT4 levels in contrast with melanomas. • Direct UVB irradiation of melanocytes did not induce ganglioside synthase genes. • Culture supernatants of UVB-irradiated keratinocytes induced ST8SIA1 in melanocytes. • TNFα and IL-6 secreted from keratinocytes enhanced ST8SIA1 expression in melanocytes. • Inflammatory cytokines induced melanoma-related ST8SIA1 in melanocytes. - Abstract: Although expression of gangliosides and their synthetic enzyme genes in malignant melanomas has been well studied, that in normal melanocytes has been scarcely analyzed. In particular, changes in expression levels of glycosyltransferase genes responsible for ganglioside synthesis during evolution of melanomas from melanocytes are very important to understand roles of gangliosides in melanomas. Here, expression of glycosyltransferase genes related to the ganglioside synthesis was analyzed using RNAs from cultured melanocytes and melanoma cell lines. Quantitative RT-PCR revealed that melanomas expressed high levels of mRNA of GD3 synthase and GM2/GD2 synthase genes and low levels of GM1/GD1b synthase genes compared with melanocytes. As a representative exogenous stimulation, effects of ultraviolet B (UVB) on the expression levels of 3 major ganglioside synthase genes in melanocytes were analyzed. Although direct UVB irradiation of melanocytes caused no marked changes, culture supernatants of UVB-irradiated keratinocytes (HaCaT cells) induced definite up-regulation of GD3 synthase and GM2/GD2 synthase genes. Detailed examination of the supernatants revealed that inflammatory cytokines such as TNFα and IL-6 enhanced GD3 synthase gene expression. These results suggest that inflammatory cytokines secreted from UVB-irradiated keratinocytes induced melanoma-associated ganglioside synthase genes, proposing roles of skin microenvironment in the promotion of melanoma-like ganglioside profiles in melanocytes.

  16. Relation entre les caractéristiques des table-bancs et les mesures anthropométriques des écoliers au Benin

    PubMed Central

    Falola, Stève Marjelin; Gouthon, Polycarpe; Falola, Jean-Marie; Fiogbe, Michel Armand; Nigan, Issiako Bio

    2014-01-01

    Introduction Le mobilier scolaire et la posture assise en classe sont souvent impliqués dans l'apparition des douleurs rachidiennes, influant de fait sur la qualité des tâches réalisées par les apprenants. Aucune étude n'a encore vérifié le degré d'adéquation entre les caractéristiques du mobilier et celles des écoliers au Bénin. L'objectif de cette étude transversale est donc de déterminer la relation entre les dimensions des table-bancs utilisées en classe et les mesures anthropométriques des écoliers au Bénin. Methods Elle a été réalisée avec un échantillon probabiliste de 678 écoliers, âgés de 4 à 17 ans. Les mesures anthropométriques des écoliers et les mensurations relatives aux longueurs, largeurs et hauteurs des table-bancs ont été mesurées, puis intégrées aux équations proposées dans la littérature. Les pourcentages des valeurs situées hors des limitesacceptables, dérivées de l'application des équations ont été calculés. Results La largeur et la hauteur des table-bancs utilisées par les écoliers étaient plus élevées (p < 0,05) que les valeurs de référence recommandées par les structures officielles de contrôle et de production des mobiliers scolaires au Bénin. Quel que soit le sexe, il y avait une inadéquation entre la largeur du banc et la longueur fesse-poplité, puis entre la hauteur de la table et la distance coude-bancdes écoliers. Conclusion Les résultats suggèrent de prendre en compte l’évolution des mesures anthropométriques des écoliers dans la confection des table-bancs, afin de promouvoir de bonnes postures assises en classe et de réduire le risque de troubles du rachis. PMID:25317232

  17. Diffusion dans les liquides

    NASA Astrophysics Data System (ADS)

    Dianoux, A. J.

    2003-09-01

    Après une brève introduction qui rappelle les concepts détaillés dans le cours de M. Bée, nous présentons un aperçu de trois de nos travaux sur l'étude de la diffusion. Tout d'abord la dynamique de l'eau, dans son état normal ou surfondu, révèle la complexité apportée par le réseau de liaisons hydrogène. Ensuite l'effet du confinement sur la dynamique de l'eau sera étudié dans le cas de la membrane Nafion. Enfin la diffusion dans les phases nématique et smectique A d'un cristal liquide permet d'obtenir la valeur du potentiel qui maintient les couches dans la phase smectique.

  18. Effet Hall et Magnetisme des Alliages Amorphes Nickel-Zirconium Fabriques Par Pulverisation

    NASA Astrophysics Data System (ADS)

    Morel, Robert

    Cette these se situe dans le cadre d'une etude des proprietes electroniques et structurales des alliages metalliques amorphes, en cours depuis quelques annees a l'Universite de Montreal. Ce programme nous a entre autres amene a caracteriser la magnetoresistivite et l'effet Hall d'alliages FeZr, CoZr et NiZr, ce qui a permis de mettre en evidence deux caracteristiques de l'effet Hall: Dans les alliages amorphes ferromagnetiques, la resistivite elevee engendre un effet Hall extraordinaire beaucoup plus important que celui enregistre dans les metaux cristallins. La polarisation des spins entrai ne une asymetrie de la diffusion qui, tant dans les phases cristalline et amorphe, est tenue responsable de cette contribution. L'autre particularite du comportement de Hall de ces systemes est le renversement de signe du coefficient de Hall ordinaire, qui passe du negatif au positif dans les echantillons plus riches en zirconium. Dans les metaux cristallins, un modele d'electrons libres predit un signe negatif a moins que la conduction ne soit dominee par les trous. Or, dans un milieu desordonne les memes concepts sont difficilement applicables et de nouvelles theories ont du etre elaborees pour expliquer ce phenomene. Jusqu'a maintenant, l'etude des alliages amorphes nickel-zirconium s'est faite surtout a partir d'echantillons fabriques par trempe sur roue. Malheureusement cette technique ne permet pas la fabrication d'alliages contenant plus de 70% de nickel, a l'exception du seul compose Ni _{90}Zr_{10 }. Pour pallier a cette lacune et etendre nos connaissance a l'ensemble de la gamme de compositions, nous avons fabrique par pulverisation cathodique des echantillons NiZr amorphes--et quelques alliages cristallins tres riches en nickel--couvrant une bonne partie de la gamme interdite par la technique de trempe sur roue. Dans un premier temps, par comparaison avec les resultats connus nous avons mis en evidence les similitudes et les differences entre les alliages obtenus par

  19. Comprendre la maltraitance des aînés en pratique familiale

    PubMed Central

    Yaffe, Mark J.; Tazkarji, Bachir

    2012-01-01

    Résumé Objectif Présenter ce qui constitue la maltraitance des aînés, ce dont les médecins de famille devraient être au courant, les signes et les symptômes laissant présager de mauvais traitements chez des adultes plus âgés, comment l’outil Elder Abuse Suspicion Index peut aider à détecter la maltraitance et les options qui existent pour réagir en cas de soupçons de maltraitance. Sources des données On a fait une recension dans MEDLINE, PsycINFO et Social Work Abstracts pour trouver des publications en français ou en anglais, de 1970 à 2011, à l’aide des expressions elder abuse, elder neglect, elder mistreatment, seniors, older adults, violence, identification, detection tools et signs and symptoms. Les publications pertinentes ont fait l’objet d’un examen. Message principal La maltraitance des aînés est une cause importante de morbidité et de mortalité chez les adultes plus âgés. Si les médecins de famille sont bien placés pour détecter des mauvais traitements infligés aux aînés, leurs taux réels de signalement de cas de maltraitance sont plus faibles que dans d’autres professions. Cette situation pourrait s’améliorer s’ils comprenaient mieux les genres d’agissements qui constituent de la maltraitance des aînés, ainsi que les signes et les symptômes observés au bureau qui pourraient pointer vers des cas de mauvais traitements. La détection de tels cas pourrait être facilitée par le recours à un court outil validé, comme l’Elder Abuse Suspicion Index. Conclusion Les médecins de famille peuvent jouer un rôle plus important dans la détection d’une éventuelle maltraitance des aînés. Une fois qu’on soupçonne de mauvais traitements, il existe dans la plupart des communautés des services sociaux ou des forces de l’ordre accessibles pour effectuer des évaluations plus approfondies et intervenir.

  20. Tuberculome de Bouchut dans la tuberculose multi focale: à propos de quatre cas

    PubMed Central

    Janah, Hicham; Alami, Ahmed; Souhi, Hicham; Zegmout, Adil; Naji-Amrani, Hicham; Raoufi, Mohamed; Elouazzani, Hanane; Rhorfi, Ismail Abderrahmani; Abid, Ahmed

    2014-01-01

    La tuberculose multifocale a connu un regain de fréquence avec la pandémie du SIDA, elle s'observe encore chez des sujets non infectés par le VIH surtout dans les pays en voie de développement notamment au Maroc. Nous rapportons quatre observations de tuberculose multifocale chez trois patients immunocompétents et un patient immunodéprimé. Quatre patients ont bénéficié d'un bilan phtisiologique, biologique, sérologique(HIV), radiologique et d'angiographie à la fluorescéine pour suspicion de tuberculose multifocale. Il s'agit de trois hommes et une femme, d’âge moyen de 44 ans, trois patients sont immunocompétents et un patient séropositif. La tuberculose intéressait trois localisations chez les quatre patients: pulmonaire dans quatre cas, ophtalmique dans quatre cas, digestive dans un cas, urinaire dans un cas, cérébrale dans un cas et un cas d'atteinte de la moelle osseuse. L'atteinte ophtalmologique est représentée par des nodules choroïdiens de Bouchut dans quatre cas et un nodule papillaire de Bouchut dans un cas; aucun des ces patients ne présentait une uvéite granulomateuse. Nos malades ont reçu un traitement anti-tuberculeux d'une durée de neuf mois avec une bonne évolution clinique, biologique, radiologique et angiographique. Au Maroc, la tuberculose continue à surprendre aussi bien par son extension touchant le sujet débilité et le sujet immunocompétent, que par ses présentations diverses y compris l'atteinte oculaire qu'elle faut rechercher par un examen ophtalmologique soigneux et systématique. PMID:25478047

  1. Les bisphosphonates dans le traitement de l’ostéoporose

    PubMed Central

    Brown, Jacques P.; Morin, Suzanne; Leslie, William; Papaioannou, Alexandra; Cheung, Angela M.; Davison, Kenneth S.; Goltzman, David; Hanley, David Arthur; Hodsman, Anthony; Josse, Robert; Jovaisas, Algis; Juby, Angela; Kaiser, Stephanie; Karaplis, Andrew; Kendler, David; Khan, Aliya; Ngui, Daniel; Olszynski, Wojciech; Ste-Marie, Louis-Georges; Adachi, Jonathan

    2014-01-01

    Résumé Objectif Exposer l’efficacité et les risques du traitement par les bisphosphonates dans la prise en charge de l’ostéoporose et décrire les patients qui seraient de bons candidats aux congés thérapeutiques. Qualité des données Une recherche dans MEDLINE (PubMed, jusqu’au 31 décembre 2012) a permis de relever les publications pertinentes pour l’inclusion. La plupart des données probantes citées sont de niveau II (tirées d’essais non randomisés, de cohorte et d’autres essais comparatifs). Message principal L’efficacité des bisphosphonates de premier recours homologués pour la prévention des fractures a été éprouvée dans le cadre d’essais cliniques randomisés et contrôlés. Cependant, l’usage clinique répandu et prolongé des bisphosphonates a donné lieu à des rapports de manifestations indésirables rares, mais graves. L’ostéonécrose maxillaire et les fractures atypiques sous-trochantériennes ou diaphysaires du fémur seraient liées à l’emploi des bisphosphonates dans le traitement de l’ostéoporose, mais ces manifestations sont extrêmement rares et lorsqu’elles surviennent, elles sont accompagnées d’autres comorbidités ou de l’emploi concomitant de médicaments. Les congés thérapeutiques ne peuvent être envisagés que chez les patients à faible risque et dans un groupe restreint de patients dont le risque de fracture est modéré après un traitement de 3 à 5 ans. Conclusion Lorsque les bisphosphonates sont prescrits à des patients dont le risque de fracture est élevé, leur effet de prévention des fractures l’emporte de loin sur leurs torts potentiels. Chez les patients qui prennent des bisphosphonates depuis 3 à 5 ans, il faut réévaluer le besoin de poursuivre le traitement.

  2. Manipulation coherente de qubits de spin dans une boite quantique triple

    NASA Astrophysics Data System (ADS)

    Gaudreau, Louis

    Nous presentons dans cette these une etude detaillee du moment magnetique intrinseque de l'electron, i.e. le spin electronique, incluant la manipulation quantique coherente des etats de spin de trois electrons couples. A cette fin, nous utilisons des boites quantiques laterales pour confiner les electrons. Ces nano-structures, d'une grandeur autour de 1 pm, permettent de confiner un nombre precis d'electrons de facon controlee, allant jusqu'a zero electrons. Les developpements technologiques et d'ingeniosite durant la derniere decennie ont permis de coupler trois boites quantiques, ainsi l'interaction entre plusieurs electrons confines peut etre controlee comme par exemple le couplage quantique tunnel et l'interaction d'echange entre les spins de chacun d'entre eux. A l'aide de boites quantiques couplees, il est possible de realiser des experiences dans plusieurs domaines de la physique moderne : les etats up et down du spin des electrons confines peuvent etre utilisees comme etats quantiques binaires (qubits) dans le domaine de l'informatique quantique, la non-localite quantique peut etre testee en separant spatialement deux electrons enchevetres, il est possible de creer des 'courants de spin enchevetres' utiles en spintronique, et bien d'autres. La manipulation coherente des etats de spin du systeme a trois electrons se fait de facon purement electrique grace a des pulses a haute frequence qui permettent d'augmenter le couplage entre les electrons et de faire la mesure de l'etat resultant apres la manipulation. Nous utilisons l'interaction hyperfine entre les spins des electrons et ceux des noyaux du cristal dans lequel ils resident pour creer les rotations quantiques entre les etats, notamment les etats |Q +3/2> et (D+1/2>. Les resultats obtenus indiquent un temps de coherence de l'ordre de 10 ns. Ces experiences demontrent un niveau de controle sans precedant de boites quantiques triples et pavent la voie vers des nano-structures plus sophistiquees dans

  3. Les reseaux de politique publique comme facteur d'influence du choix des instruments de politique energetique canadienne a des fins environnementales de 1993 a nos jours

    NASA Astrophysics Data System (ADS)

    Fathy El Dessouky, Naglaa

    Au cours de la derniere decennie, les modes de la gouvernance ont pris place dans un contexte totalement different de celui qu'ils avaient auparavant. Les gouvernements modernes se rendent compte qu'ils perdent de plus en plus leur capacite a elaborer et a gerer les changements d'une maniere autonome. Ainsi, les fonctions et les activites traditionnellement accomplies exclusivement par le gouvernement engagent de nos jours une gamme d'acteurs etatiques et non etatiques. A l'encontre du concept traditionnel de l'Etat controleur, la gouvernance contemporaine est ainsi devenue moins une question d'offre de service et davantage une gestion indirecte des reseaux de politique publique. Dans cette entreprise, les gouvernements contemporains, cherchant plus d'information, de soutien et de legitimite en matiere de formulation des decisions, ont besoin d'etablir des relations avec les divers groupes d'interet qui, a leur tour, voulaient plus de promotion et de protection en faveur de leurs interets a travers leur implication au processus de l'elaboration et de la mise en oeuvre des politiques publiques. Ainsi, l'approche des reseaux de politique publique represente aujourd'hui un courant considerable au sein du champ d'analyse des politiques publiques. Toutefois, les preoccupations des chercheurs pour cette approche, dans le domaine des politiques energetiques a des fins environnementales, semblent recentes, et les etudes realisees sont encore trop peu nombreuses. Au Canada, au debut des annees 1990, le gouvernement ainsi que plusieurs groupes d'interets, des differents secteurs energetique, industriel et environnemental, ont commence a intensifier leurs efforts pour s'attaquer au probleme du changement climatique d'origine energetique, genere surtout par le secteur de l'industrie. Au cours de la derniere decennie, la question touchant plutot le sujet du developpement energetique durable represente le plus important domaine des politiques publiques ayant surgi recemment dans

  4. Integration des sciences et de la langue: Creation et experimentation d'un modele pedagogique pour ameliorer l'apprentissage des sciences en milieu francophone minoritaire

    NASA Astrophysics Data System (ADS)

    Cormier, Marianne

    Les faibles resultats en sciences des eleves du milieu francophone minoritaire, lors d'epreuves au plan national et international, ont interpelle la recherche de solutions. Cette these avait pour but de creer et d'experimenter un modele pedagogique pour l'enseignement des sciences en milieu linguistique minoritaire. En raison de la presence de divers degres de francite chez la clientele scolaire de ce milieu, plusieurs elements langagiers (l'ecriture, la discussion et la lecture) ont ete integres a l'apprentissage scientifique. Nous avions recommande de commencer le processus d'apprentissage avec des elements langagiers plutot informels (redaction dans un journal, discussions en dyades...) pour progresser vers des activites langagieres plus formelles (redaction de rapports ou d'explications scientifiques). En ce qui a trait a l'apprentissage scientifique, le modele preconisait une demarche d'evolution conceptuelle d'inspiration socio-constructiviste tout en s'appuyant fortement sur l'apprentissage experientiel. Lors de l'experimentation du modele, nous voulions savoir si celui-ci provoquait une evolution conceptuelle chez les eleves, et si, simultanement, le vocabulaire scientifique de ces derniers s'enrichissait. Par ailleurs, nous cherchions a comprendre comment les eleves vivaient leurs apprentissages dans le cadre de ce modele pedagogique. Une classe de cinquieme annee de l'ecole de Grande-Digue, dans le Sud-est du Nouveau-Brunswick, a participe a la mise a l'essai du modele en etudiant les marais sales locaux. Lors d'entrevues initiales, nous avons remarque que les connaissances des eleves au sujet des marais sales etaient limitees. En effet, s'ils etaient conscients que les marais etaient des lieux naturels, ils ne pouvaient pas necessairement les decrire avec precision. Nous avons egalement constate que les eleves utilisaient surtout des mots communs (plantes, oiseaux, insectes) pour decrire le marais. Les resultats obtenus indiquent que les eleves ont

  5. Résultats du traitement du synovialosarcome des members

    PubMed Central

    Lukulunga, Loubet Unyendje; Moussa, Abdou Kadri; Mahfoud, Mustapha; El Bardouni, Ahmed; Ismail, Farid; Kharmaz, Mohammed; Berrada, Mohamed Saleh; El Yaacoubi, Moradh

    2014-01-01

    Les synovialosarcomes, sarcomes de haut grade, sont de diagnostic tardif et le traitement est complexe et onéreux, nécessitant la mise en œuvre d'une équipe pluridisciplinaire. Le but de ce travail était d'apprécier les résultats de l'association de la chirurgie à la radio chimiothérapie des synovialosarcomes des membres. Il s'agissait d'une étude rétrospective portant sur des patients présentant de synovialosarcomes des membres pris en charge dans le service de chirurgie orthopédique et traumatologique du CHU Ibn SINA de Rabat allant de Janvier 2006 à Décembre 2011 (6 ans). Nous avons inclus les malades présentant de synovialosarcomes des membres dont la clinique et l'imagerie médicale étaient en faveur, confirmés par l'examen anatomopathologique et la prise en charge effectuée dans le service. Les patients ont été revus avec un recul moyen de 3 ans. Nous n'avons pas retenu les patients dont les dossiers étaient incomplets, perdus de vue. Nous avons apprécié les résultats selon les critères carcinologiques et le score MSTS (Musculoskeletal Tumor Society). La saisie et l'analyse des données ont été faites sur le logiciel SPSS Stastic 17.0 Nous avons colligé 20 cas de synovialosarcome des membres dans le Service de Chirurgie Orthopédique et Traumatologique au CHU Ibn SINA de Rabat Le sexe masculin a prédominé avec 65% (n = 13) avec un sex ratio 1,85. L’âge moyen a été de 42,6 ans avec des extrêmes allant de 20 ans et 70 ans. Notre délai moyen de consultation était de 14,42 mois. Tous les malades ont consulté pour une tuméfaction dans 100% (localisée au membre inférieur dans 65% (n = 13), membre supérieur dans 35% (n = 7). La douleur était associée à la tuméfaction dans 55% (n = 11), quant à l'altération de l’état général et l'ulcération de la masse, elles ont été notées dans 3 cas chacune. Nous avons réalisé un bilan d'imagerie médicale comprenant: radiographie standard, échographie, écho doppler

  6. Modelisations des effets de surface sur les jets horizontaux subsoniques d'hydrogene et de methane

    NASA Astrophysics Data System (ADS)

    Gomez, Luis Fernando

    Le developpement des codes et de normes bases sur une methodologie scientifique requiert la capacite de predire l'etendue inflammable de deversements gazeux d'hydrogene sous differentes conditions. Des etudes anterieures ont deja etabli des modeles bases sur les lois de conservation de la mecanique des fluides basees sur des correlations experimentales qui permettent de predire la decroissance de la concentration et de la vitesse d'un gaz le long de l'axe d'un jet libre vertical. Cette etude s'interesse aux effets de proximite a une surface horizontale parallele sur un jet turbulent. Nous nous interessons a son impact sur l'etendue du champ de la concentration et sur l'enveloppe inflammable en particulier. Cette etude est comparative : l'hydrogene est compare au methane. Ceci permet de degager l'influence des effets de difference de la densite sur le comportement du jet, et de comparer le comportement de l'hydrogene aux correlations experimentales, qui ont ete essentiellement etablies pour le methane. Un modele decrivant l'evolution spatio-temporelle du champ de concentration du gaz dilue est propose, base sur la mecanique des fluides computationnelle. Cette approche permet de varier systematiquement les conditions aux frontieres (proximite du jet a la surface, par exemple) et de connaitre en detail les proprietes de l'ecoulement. Le modele est implemente dans le code de simulations par volumes finis de FLUENT. Les resultats des simulations sont compares avec les lois de similitudes decoulant de la theorie des jets d'ecoulements turbulents libres ainsi qu'avec les resultats experimentaux disponibles. L'effet de la difference des masses molaires des constituantes du jet et des constituantes du milieu de dispersion est egalement etudie dans le contexte du comportement d'echelle de la region developpee du jet.

  7. Annuaire du bureau des Longitudes : guide de données astronomiques 2011 pour l'observation du ciel

    NASA Astrophysics Data System (ADS)

    Institut de Mécanique Céleste Et de Calcul Des Ephémérides (Imcce); Bureau Des Longitudes (Bdl)

    2010-07-01

    Destiné aux astronomes, professionnels ou amateurs, cet ouvrage se décompose de la façon suivante : Les trois premiers chapitres de cet ouvrage contiennent : les données sur les différents calendriers et leur concordance, les fêtes légales en France, les différentes échelles de temps, les dates de décrets sur les heures légales en France métropolitaine parues au Journal Officiel depuis 1916 ; des notions nécessaires à la compréhension et à l'emploi des éphémérides contenues dans l'ouvrage. Les chapitres suivant fournissent des éphémérides astronomiques : les positions du Soleil et de la Lune ; les positions des planètes et de leurs satellites ; les positions des astéroïdes et des comètes ; les explications et des données pour l'observation de la surface du Soleil, de la Lune et des planètes ; des cartes du ciel, une liste de constellations et les positions et occultations des étoiles ; des données sur les éclipses de Soleil et de Lune et sur les phénomènes astronomiques ; la liste des observatoires astronomiques les plus connus.

  8. Annuaire du bureau des Longitudes : guide de données astronomiques 2012 pour l'observation du ciel

    NASA Astrophysics Data System (ADS)

    Institut de Mécanique Céleste Et de Calcul Des Ephémérides (Imcce); Bureau Des Longitudes (Bdl)

    2011-07-01

    Destiné aux astronomes, professionnels ou amateurs, cet ouvrage se décompose de la façon suivante : Les trois premiers chapitres de cet ouvrage contiennent : les données sur les différents calendriers et leur concordance, les fêtes légales en France, les différentes échelles de temps, les dates de décrets sur les heures légales en France métropolitaine parues au Journal Officiel depuis 1916 ; des notions nécessaires à la compréhension et à l'emploi des éphémérides contenues dans l'ouvrage. Les chapitres suivant fournissent des éphémérides astronomiques : les positions du Soleil et de la Lune ; les positions des planètes et de leurs satellites ; les positions des astéroïdes et des comètes ; les explications et des données pour l'observation de la surface du Soleil, de la Lune et des planètes ; des cartes du ciel, une liste de constellations et les positions et occultations des étoiles ; des données sur les éclipses de Soleil et de Lune et sur les phénomènes astronomiques ; la liste des observatoires astronomiques les plus connus.

  9. Etude de la formation de resonances electroniques et de leur role dans la fragmentation neutre de molecules d'interet biologique

    NASA Astrophysics Data System (ADS)

    Lepage, Martin

    1998-12-01

    Cette these est presentee a la Faculte de medecine de l'Universite de Sherbrooke en vue de l'obtention du grade de Ph.D. en Radiobiologie. Elle contient des resultats experimentaux enregistres avec un spectrometre d'electrons a haute resolution. Ces resultats portent sur la formation de resonances electroniques en phase condensee et de differents canaux pour leur decroissance. En premier lieu, nous presentons des mesures d'excitations vibrationnelles de l'oxygene dilue en matrice d'argon pour des energies des electrons incidents de 1 a 20 eV. Les resultats suggerent que le temps de vie des resonances de l'oxygene est modifie par la densite d'etats d'electrons dans la bande de conduction de l'argon. Nous presentons aussi des spectres de pertes d'energie d'electrons des molecules de tetrahydrofuranne (THF) et d'acetone. Dans les deux cas, la position en energie des pertes associees aux excitations vibrationnelles est en excellent accord avec les resultats trouves dans la litterature. Les fonctions d'excitation de ces modes revelent la presence de plusieurs nouvelles resonances electroniques. Nous comparons les resonances du THF et celles de la molecule de cyclopentane en phase gazeuse. Nous proposons une origine commune aux resonances ce qui implique qu'elles ne sont pas necessairement attribuees a l'excitation des electrons non-apparies de l'oxygene du THF. Nous proposons une nouvelle methode basee sur la spectroscopie par pertes d'energie des electrons pour detecter la production de fragments neutres qui demeurent a l'interieur d'un film mince condense a basse temperature. Cette methode se base sur la detection des excitations electroniques du produit neutre. Nous presentons des resultats de la production de CO dans un film de methanol. Le taux de production de CO en fonction de l'energie incidente des electrons est calibre en termes d'une section efficace totale de diffusion des electrons. Les resultats indiquent une augmentation lineaire du taux de production de

  10. Sacroiliites infectieuses dans le centre tunisien: étude rétrospective de 25 cas

    PubMed Central

    Bellazreg, Foued; Alaya, Zeineb; Hattab, Zouhour; Lasfar, Nadia Ben; Ayeche, Mohamed Laziz Ben; Bouajina, Elyes; Letaief, Amel; Hachfi, Wissem

    2016-01-01

    Les sacroiliites infectieuses sont rares mais peuvent se compliquer de séquelles fonctionnelles invalidantes. Décrire les caractéristiques cliniques et bactériologiques des sacroiliites infectieuses chez les patients suivis à Sousse, Centre Tunisien. Etude rétrospective, descriptive, des cas de sacroiliites infectieuses chez les patients hospitalisés à Sousse entre 2000 et 2015. Le diagnostic a été retenu devant des signes cliniques, d'imagerie, et microbiologiques évocateurs. Vingt-cinq patients, 10 hommes et 15 femmes, d’âge moyen 41 ans (19-78) ont été inclus. Les sacroiliites étaient dues à des bactéries pyogènes dans 14 cas (56%), brucelliennes dans 6 cas (24%), et tuberculeuses dans 5 cas (20%). La durée moyenne d’évolution était de 61, 45 et 402 jours respectivement. Les signes cliniques les plus fréquents étaient les douleurs fessières (92%) et la fièvre (88%). La radiographie standard était anormale dans 75% des cas. La TDM et l'IRM sacro-iliaques dans tous les cas. Le diagnostic a été confirmé bactériologiquement dans 24 cas (96%). La durée moyenne d'antibiothérapie était de 83 jours dans les sacroiliites à pyogènes, et de 102 jours dans les SI brucelliennes. L’évolution était favorable chez 12 patients (48%), 9 patients (36%) ont gardé une douleur sacro-iliaque séquellaire, et 4 patients (16%) sont décédés. Dans notre étude, la durée d’évolution de la sacroiliite infectieuse ne permettait pas de prédire la bactérie responsable, d'où la nécessité d'obtenir une documentation bactériologique afin de prescrire une antibiothérapie appropriée. PMID:27583067

  11. Fissuration en relaxation des aciers inoxydables austénitiques au voisinage des soudures

    NASA Astrophysics Data System (ADS)

    Auzoux, Q.; Allais, L.; Gourgues, A. F.; Pineau, A.

    2003-03-01

    Des fissures intergranulaires peuvent se développer au voisinage des soudures des aciers inoxydables austénitiques lorsqu'ils sont réchauffés dans le domaine de température compris entre 500^{circ}C et 700^{circ}C. A ces températures, les contraintes résiduelles post-soudage se relaxent par déformation viscoplastique. Il peut arriver que ces zones proches de la soudure soient tellement fragiles, qu'elles ne puissent accommoder cette faible déformation. Afin de préciser quelles peuvent être les modifications microstructurales qui conduisent à une telle fragilisation, on a examiné les microstructures de ces zones et révélé ainsi un écrouissage résiduel, responsable d'une forte élévation de la dureté. On a pu reproduire par hypertrempe puis laminage entre 400^{circ}C et 600^{circ}C une microstructure similaire. Des essais mécaniques (traction, fluage, relaxation, sur éprouvettes lisses et pré-fissurées) ont été réalisés à 550^{circ}C et à 600^{circ}C sur ces zones affectées simulées et sur un état de référence hypertrempé. Ils ont montré que l'écrouissage diminuait la ductilité dans le domaine de rupture intergranulaire, sans modifier qualitativement le mécanisme d'endommagement. Pendant la pré-déformation les incompatibilités de déformation entre grains conduiraient à l'existence de contraintes locales élevées qui favoriseraient la germination des cavités intergranulaires.

  12. Etiologies des hypertensions artérielles endocrines: à propos d'une série de cas

    PubMed Central

    Bouznad, Naima; El Mghari, Ghizlane; El Ansari, Nawal

    2016-01-01

    Les hypertensions artérielles (HTA) d'origine endocrine restent une cause rare d'HTA, sa prévalence globale n'excède pas 4% des hypertendus. L'intérêt de la recherche des HTA endocrines réside dans la gravité de certaines formes parfois mortelles et le caractère potentiellement curable et réversible de ces HTA. Le but du travail est de déterminer le profil clinique, para clinique, étiologique et thérapeutique des HTA secondaires d'origine endocrine chez les patients suivis au service d'endocrinologie au CHU Mohamed IV à Marrakech. Il s'agit d'une étude descriptive prospective s’étalant sur une période de 4 ans incluant 45 patients ayant une HTA endocrinienne. La moyenne d’âge est de 44,89 ans, avec une nette prédominance du sexe féminine (sexe ratio de 0,49). Les étiologies des HTA endocrines étaient dominées par le phéochromocytome (17 cas), l'hypercorticisme (11 cas) et l'acromégalie (8 cas). L'HTA était paroxystique dans 24,4%. Elle était d'emblée sevère classée grade 3 dans 40% des cas. L'HTA a été compliquée de cardiopathie dans 24% des cas et de néphropathie dans 20% des cas. Le traitement curatif a permis une guérison de l'HTA chez 60% (27 cas). Le diagnostic des HTA secondaires endocrines est parfois difficile du fait de l'absence de spécificité clinique. Il n'est pas exceptionnel que l'HTA soit l'unique manifestation de la maladie. Dans notre travail nous notons le caractère paroxystique et sévère de l'HTA. Le caractère éventuellement curable des HTA endocrines, dans plus des deux tiers des cas, fait qu'il est important de la dépister devant toute HTA sévère, résistante au traitement, ou en présence de signes cliniques, biologiques ou radiologiques évocateurs. PMID:27303586

  13. Immunocytochemical Localization and Biochemical Characterization of alpha-Melanocyte-Stimulating Hormon in the Brain of the Rainbow Trout, Salmo gairdneri.

    PubMed

    Vallarino, M; Delbende, C; Ottonello, I; Tranchand-Bunel, D; Jegou, S; Vaudry, H

    1989-02-01

    Abstract The distribution of alpha-melanocyte-stimulating hormone (alpha-MSH)-like immunoreactivity in the central nervous system of the rainbow trout Salmo gairdneri was investigated by indirect immunofluorescence and peroxidase-antiperoxidase techniques, using a highly specific antiserum generated in rabbits against synthetic alpha-MSH. Immunoreactive perikarya were exclusively observed in the basal hypothalamus within the pars anterioris of the nucleus lateralis tuberis. In this region, a moderate number of small stained cell bodies were observed surrounding the dorsal wall of the anterior infundibular recess. These immunoreactive cells were organized in rostro-caudal rows extending over the whole portion of the nucleus. Positive fibres originating from these perikarya were visualized in the dorsal posterior lobe and the ventral hypothalamus. A dense tract of immunoreactive fibres projected ventrally through the pituitary stalk and terminated in the neurohypophysis. The concentrations of alpha-MSH in different regions of the brain were measured by means of a sensitive and specific radioimmunoassay. The dilution curves obtained with synthetic alpha-MSH and serial dilutions of diencephalon, mesencephalon, medulla oblongata, telencephalon or pituitary extracts were strictly parallel. The highest concentration of alpha-MSH in brain was found in the diencephalon (1.31 +/- 0.07 ng/mg protein). In contrast alpha-MSH was not detectable in cerebellar extracts. Reverse-phase high-performance liquid chromatography and radioimmunoassay were used to characterize alpha-MSH-like peptides in the trout brain and pituitary. Two major forms of immunoreactive alpha-MSH were resolved by high performance liquid chromatography in hypothalamic extracts; these peptides exhibited the same retention times as des-Na-acetyl alpha-MSH and its sulfoxide derivative, respectively. Additional peaks of alpha-MSH immunoreactive material were detected in pituitary extract. These latter peptides

  14. Study on the effects of nylon-chitosan-blended membranes on the spheroid-forming activity of human melanocytes.

    PubMed

    Lin, Sung-Jan; Hsiao, Wen-Chu; Jee, Shiou-Hwa; Yu, Hsin-Su; Tsai, Tsen-Fang; Lai, Juin-Yih; Young, Tai-Horng

    2006-10-01

    Though reported limitedly in tissue engineering, modification of cellular functions can be achieved by culturing them into multicellular spheroids. We have shown melanocytes form spheroids on chitosan surface. However, how biomaterials promote spheroid formation has never been systemically investigated. In this work, nylon, which inhibits melanocyte spheroid formation, and chitosan, which promotes melanocyte spheroid formation, are used to prepare nylon/chitosan-blended membranes. Membranes composed of pure nylon, pure chitosan and various ratios of nylon and chitosan are employed to examine their effects on spheroid formation. Melanocytes show better adhesion to nylon membranes than that to chitosan membranes. In blended membranes, as more nylon is incorporated, cell adhesion increases and the trend for spheroid formation decreases. Melanocytes can only form spheroids on membranes with poorer cell adhesion. Examining the surface of the blended membranes shows phase separation of nylon and chitosan. As nylon content increases, the nylon phase on the membrane surface increases and thereby enhances cell adhesion. The opposite trend for cell adhesion and spheroid formation substantiates our hypothesis of spheroid formation on biomaterials: a balance between cell-substrate interaction and cell-cell interaction. The decrease in cell-substrate interaction tilts the balance to a state more favorable for spheroid formation. Our work can serve as a model to investigate the relative strengths of cell-cell and cell-substrate interactions and also pave way to design blended membranes with desired physical properties while preserving the spheroid-forming activity. PMID:16777216

  15. A Varp-Binding Protein, RACK1, Regulates Dendrite Outgrowth through Stabilization of Varp Protein in Mouse Melanocytes.

    PubMed

    Marubashi, Soujiro; Ohbayashi, Norihiko; Fukuda, Mitsunori

    2016-08-01

    Varp (VPS9-ankyrin repeat protein) in melanocytes is thought to function as a key player in the pigmentation of mammals. Varp regulates two different melanocyte functions: (i) transport of melanogenic enzymes to melanosomes by functioning as a Rab32/38 effector and (ii) promotion of dendrite outgrowth by functioning as a Rab21-guanine nucleotide exchange factor. The Varp protein level has recently been shown to be negatively regulated by proteasomal degradation through interaction of the ankyrin repeat 2 (ANKR2) domain of Varp with Rab40C. However, the molecular mechanisms by which Varp escapes from Rab40C and retains its own expression level remain completely unknown. Here, we identified RACK1 (receptor of activated protein kinase C 1) as a Varp-ANKR2 binding partner and investigated its involvement in Varp stabilization in mouse melanocytes. The results showed that knockdown of endogenous RACK1 in melanocytes caused dramatic reduction of the Varp protein level and inhibition of dendrite outgrowth, and intriguingly, overexpression of RACK1 inhibited the interaction between Varp and Rab40C and counteracted the negative effect of Rab40C on dendrite outgrowth. These findings indicated that RACK1 competes with Rab40C for binding to the ANKR2 domain of Varp and regulates dendrite outgrowth through stabilization of Varp in mouse melanocytes. PMID:27066885

  16. Gene Expression Analysis of Zebrafish Melanocytes, Iridophores, and Retinal Pigmented Epithelium Reveals Indicators of Biological Function and Developmental Origin

    PubMed Central

    Higdon, Charles W.; Mitra, Robi D.; Johnson, Stephen L.

    2013-01-01

    In order to facilitate understanding of pigment cell biology, we developed a method to concomitantly purify melanocytes, iridophores, and retinal pigmented epithelium from zebrafish, and analyzed their transcriptomes. Comparing expression data from these cell types and whole embryos allowed us to reveal gene expression co-enrichment in melanocytes and retinal pigmented epithelium, as well as in melanocytes and iridophores. We found 214 genes co-enriched in melanocytes and retinal pigmented epithelium, indicating the shared functions of melanin-producing cells. We found 62 genes significantly co-enriched in melanocytes and iridophores, illustrative of their shared developmental origins from the neural crest. This is also the first analysis of the iridophore transcriptome. Gene expression analysis for iridophores revealed extensive enrichment of specific enzymes to coordinate production of their guanine-based reflective pigment. We speculate the coordinated upregulation of specific enzymes from several metabolic pathways recycles the rate-limiting substrate for purine synthesis, phosphoribosyl pyrophosphate, thus constituting a guanine cycle. The purification procedure and expression analysis described here, along with the accompanying transcriptome-wide expression data, provide the first mRNA sequencing data for multiple purified zebrafish pigment cell types, and will be a useful resource for further studies of pigment cell biology. PMID:23874447

  17. Calcium homeostasis in human melanocytes: role of transient receptor potential melastatin 1 (TRPM1) and its regulation by ultraviolet light

    PubMed Central

    Devi, Sulochana; Kedlaya, Rajendra; Maddodi, Nityanand; Bhat, Kumar M. R.; Weber, Craig S.; Valdivia, Hector

    2009-01-01

    Transient receptor potential melastatin (TRPM) is a subfamily of ion channels that are involved in sensing taste, ambient temperature, low pH, osmolarity, and chemical ligands. Melastatin 1/TRPM1, the founding member, was originally identified as melanoma metastasis suppressor based on its expression in normal pigment cells in the skin and the eye but not in aggressive, metastasis-competent melanomas. The role of TRPM1 and its regulation in normal melanocytes and in melanoma progression is not understood. Here, we studied the relationship of TRPM1 expression to growth and differentiation of human epidermal melanocytes. TRPM1 expression and intracellular Ca2+ levels are significantly lower in rapidly proliferating melanocytes compared to the slow growing, differentiated melanocytes. We show that lentiviral short hairpin RNA (shRNA)-mediated knockdown of TRPM1 results in reduced intracellular Ca2+ and decreased Ca2+ uptake suggesting a role for TRPM1 in Ca2+ homeostasis in melanocytes. TRPM1 knockdown also resulted in a decrease in tyrosinase activity and intracellular melanin pigment. Expression of the tumor suppressor p53 by transfection or induction of endogenous p53 by ultraviolet B radiation caused repression of TRPM1 expression accompanied by decrease in mobilization of intracellular Ca2+ and uptake of extracellular Ca2+. These data suggest a role for TRPM1-mediated Ca2+ homeostasis, which is also regulated by ultraviolet B, in melanogenesis. PMID:19587221

  18. FK506 positively regulates the migratory potential of melanocyte-derived cells by enhancing syndecan-2 expression.

    PubMed

    Jung, Hyejung; Oh, Eok-Soo

    2016-07-01

    Although topical tacrolimus (FK506) is known to promote repigmentation by increasing the pigmentation and migration of melanocytes, the mechanism through which FK506 regulates cell migration remains unclear. Here, we report that FK506 treatment enhanced cell spreading on laminin-332 and increased migration in both melanocytes and melanoma cells. Interestingly, FK506 also increased the expression of syndecan-2, a transmembrane heparan sulfate proteoglycan through c-jun terminal kinase activation. Moreover, siRNA-mediated reduction of syndecan-2 expression decreased FK506-mediated cell spreading and migration in melanoma cells and decreased focal adhesion kinase phosphorylation in both melanocytes and melanoma cells. Consistent with these effects on syndecan-2 expression, FK506 enhanced the membrane and melanosome localizations of PKCβII, a regulator of tyrosinase activity. This suggests that FK506 may play a dual regulatory role by affecting both melanogenesis and migration in melanocyte-derived cells. Interestingly, however, FK506 failed to show any synergistic effect on the migration of UVB-treated melanocyte-derived cells. Taken together, these data indicate that FK506 regulates cell migration by enhancing syndecan-2 expression, further suggesting that syndecan-2 could be a potential target for the treatment of patients with vitiligo. PMID:27060922

  19. A comparative study of mitochondrial ultrastructure in melanocytes from perilesional vitiligo skin and perilesional halo nevi skin.

    PubMed

    Ding, Gao-Zhong; Zhao, Wen-E; Li, Xue; Gong, Qing-Li; Lu, Yan

    2015-04-01

    Vitiligo and halo nevi are both pigmentary disorders of the skin characterized by the acquired loss of functional epidermal melanocytes manifesting as white macules and patches. The cellular mechanism(s) and biochemical changes that result in the appearance of these two types of achromic lesions are still uncertain; and the relationship between vitiligo and halo nevi has been in dispute. In this study, we investigated the ultrastructure of mitochondria in melanocytes and in keratinocytes from perilesional vitiligo skin and from perilesional halo nevi skin using Transmission Electron Microscopy. Furthermore, we performed a quantitative analysis of mitochondrial morphology through a stereological study. As previously reported, we found that melanocytes from perilesional active vitiligo skin were loosely connected with their surroundings by their retracted dendrites. The surface density and the volume density of mitochondria in melanocytes and in keratinocytes from perilesional vitiligo skin are increased significantly compared with the controls, especially in active vitiligo. In contrast, there are no significant differences in mitochondria in melanocytes and in keratinocytes from perilesional halo nevi skin compared with the controls. In summary, the tendency of different morphologic alterations in mitochondria from perilesional vitiligo skin and from perilesional halo nevi skin reflect heterogeneous backgrounds between the two diseases, revealing that vitiligo and halo nevi may have separate pathogenic mechanisms. These findings may help elucidate the relationship of these two diseases and their underlying mechanisms. PMID:25672813

  20. Allier théorie et pratique dans la lutte contre la pandémie du Sida

    PubMed Central

    Zerbo, Roger

    2014-01-01

    Le premier cas d'infection par le VIH a été notifié en 1986 au Burkina Faso. L'ignorance qui entourait cette infection et l'absence de traitement curatif a amplifié ses conséquences sociales et économiques. La mise en œuvre des interventions communautaire est un enjeu majeur actuel qui recommande la compréhension des logiques sociales endogènes qui influencent les comportements individuels et collectifs. C'est en cela que l'implication des sciences sociales dans la lutte contre les maladies, en particulier le Sida constitue un enjeu, en termes de définition et d'identification de leur contribution. Dans notre propos, nous pouvons mettre en évidence trois niveaux de contribution des sciences sociales, notamment la sociologie, l'anthropologie, la psychologie et dans une certaine mesure le droit et l’économie, à la prévention du Sida et la prise en charge des personnes infectées par le VIH. Il faut noter que ces disciplines contribuent à la lutte contre le VIH d'une part, par des réflexions et des éléments d'analyses constructives, et d'autre part, l'aptitude des porteurs de ces disciplines est parfois sollicitée pour l'efficacité de la mise en œuvre des actions et l'organisation des systèmes de soins. PMID:25722761

  1. Lignes directrices canadiennes sur l’utilisation sécuritaire et efficace des opioïdes pour la douleur chronique non cancéreuse

    PubMed Central

    Kahan, Meldon; Wilson, Lynn; Mailis-Gagnon, Angela; Srivastava, Anita

    2011-01-01

    Résumé Objectif Présenter aux médecins de famille un résumé clinique pratique sur la prescription d’opioïdes à des populations particulières en se fondant sur les recommandations faites dans les lignes directrices canadiennes sur l’utilisation sécuritaire et efficace des opioïdes pour la douleur chronique non cancéreuse. Qualité des données Pour produire les lignes directrices, les chercheurs ont effectué une synthèse critique de la littérature médicale en insistant plus précisément sur les études de l’efficacité et de la sécurité des opioïdes dans des populations particulières. Message principal Les médecins de famille peuvent atténuer les risques de surdose, de sédation, d’usage abusif et de dépendance grâce à des stratégies adaptées à l’âge et à l’état de santé des patients. Dans le cas de patients à risque de dépendance, on devrait réserver les opioïdes aux douleurs nociceptives ou neuropathiques bien définies qui n’ont pas répondu aux traitements de première intention. Il faut procéder lentement au titrage des opioïdes, avec des dispensations fréquentes et une étroite surveillance pour dépister tout signe d’usage abusif. Une dépendance aux opioïdes suspectée est prise en charge au moyen d’une thérapie structurée aux opioïdes, d’un traitement à la méthadone ou à la buprénorphine ou encore d’un traitement fondé sur l’abstinence. Les patients souffrant de troubles de l’humeur ou d’anxiété ont tendance à avoir une réponse analgésique atténuée aux opioïdes, sont à risque plus élevé d’usage abusif et prennent souvent des sédatifs qui interagissent défavorablement avec les opioïdes. Il faut prendre des précautions semblables à celles utilisées avec d’autres patients à risque élevé. Il faut faire un sevrage progressif si la douleur du patient demeure sévère même avec un essai adéquat de thérapie aux opioïdes. Chez les personnes âgées, la s

  2. Gestion des ressources hydriques adaptee aux changements climatiques pour la production optimale d'hydroelectricite. Etude de cas: Bassin versant de la riviere Manicouagan

    NASA Astrophysics Data System (ADS)

    Haguma, Didier

    Il est dorenavant etabli que les changements climatiques auront des repercussions sur les ressources en eau. La situation est preoccupante pour le secteur de production d'energie hydroelectrique, car l'eau constitue le moteur pour generer cette forme d'energie. Il sera important d'adapter les regles de gestion et/ou les installations des systemes hydriques, afin de minimiser les impacts negatifs et/ou pour capitaliser sur les retombees positives que les changements climatiques pourront apporter. Les travaux de la presente recherche s'interessent au developpement d'une methode de gestion des systemes hydriques qui tient compte des projections climatiques pour mieux anticiper les impacts de l'evolution du climat sur la production d'hydroelectricite et d'etablir des strategies d'adaptation aux changements climatiques. Le domaine d'etude est le bassin versant de la riviere Manicouagan situe dans la partie centrale du Quebec. Une nouvelle approche d'optimisation des ressources hydriques dans le contexte des changements climatiques est proposee. L'approche traite le probleme de la saisonnalite et de la non-stationnarite du climat d'une maniere explicite pour representer l'incertitude rattachee a un ensemble des projections climatiques. Cette approche permet d'integrer les projections climatiques dans le probleme d'optimisation des ressources en eau pour une gestion a long terme des systemes hydriques et de developper des strategies d'adaptation de ces systemes aux changements climatiques. Les resultats montrent que les impacts des changements climatiques sur le regime hydrologique du bassin de la riviere Manicouagan seraient le devancement et l'attenuation de la crue printaniere et l'augmentation du volume annuel d'apports. L'adaptation des regles de gestion du systeme hydrique engendrerait une hausse de la production hydroelectrique. Neanmoins, une perte de la performance des installations existantes du systeme hydrique serait observee a cause de l'augmentation des

  3. Risk Factors and Relationship of Cutaneous and Uveal Melanocytic Lesions in Monozygotic and Dizygotic Twin Pairs

    PubMed Central

    Varga, Anita; Szabó, Hajnalka; Orvos, Hajnalka; Kemény, Lajos; Oláh, Judit

    2016-01-01

    Background The similar genetic background of a pair of twins, and the similar environmental impacts to which they are exposed allow an exact and objective investigation of various constitutional and environmental factors in naevus development. As far as we are aware, this is the first published survey that simultaneously examines cutaneous and ocular pigmented lesions in an appreciable sample of identical and non-identical twins. Methods 172 pairs of twins of Caucasian origin were included in this study. A whole-body skin examination and a detailed ophthalmological examination were performed to determine the density of melanocytic lesions. A standardized questionnaire was used to assess the data relating to constitutional, sun exposure and other variables. Results A notably high proportion of the subjects (36.78%) manifested one or more clinically atypical melanocytic naevi (CAMNs), and approximately one-third (31.4%) of them at least one benign uveal pigmented lesion (BUPL). The incidence of iris freckles (IFs), iris naevi (INs) and choroidal naevi (CHNs) proved to be 25.35%, 5.98% and 3.52%, respectively. The interclass correlation coefficients for common melanocytic naevi (CMNs), CAMNs, and INs were 0.77, 0.76 and 0.86 in monozygotic twins, as compared with 0.5, 0.27 and 0.25 in dizygotic twin pairs, respectively. A statistically significant correlation was found between the prevalence of CAMNs and that of INs. Conclusions This significant correlation suggests the existence of a subgroup of Caucasian people with an increased susceptibility to both cutaneous and ocular naevus formation. There is accumulating evidence that, besides the presence of cutaneous atypical naevi, INs can serve as a marker of a predisposed phenotype at risk of uveal melanoma. The correlation between cutaneous and ocular pigmented lesions underlines the need for the adequate ophthalmological screening of subjects with CAMNs and INs. PMID:27486750

  4. Knowledge Building Insights on Biomarkers of Arsenic Toxicity to Keratinocytes and Melanocytes

    PubMed Central

    Isokpehi, Raphael D.; Udensi, Udensi K.; Anyanwu, Matthew N.; Mbah, Andreas N.; Johnson, Matilda O.; Edusei, Kafui; Bauer, Michael A.; Hall, Roger A.; Awofolu, Omotayo R.

    2012-01-01

    Exposure to inorganic arsenic induces skin cancer and abnormal pigmentation in susceptible humans. High-throughput gene transcription assays such as DNA microarrays allow for the identification of biological pathways affected by arsenic that lead to initiation and progression of skin cancer and abnormal pigmentation. The overall purpose of the reported research was to determine knowledge building insights on biomarker genes for arsenic toxicity to human epidermal cells by integrating a collection of gene lists annotated with biological information. The information sets included toxicogenomics gene-chemical interaction; enzymes encoded in the human genome; enriched biological information associated with genes; environmentally relevant gene sequence variation; and effects of non-synonymous single nucleotide polymorphisms (SNPs) on protein function. Molecular network construction for arsenic upregulated genes TNFSF18 (tumor necrosis factor [ligand] superfamily member 18) and IL1R2 (interleukin 1 Receptor, type 2) revealed subnetwork interconnections to E2F4, an oncogenic transcription factor, predominantly expressed at the onset of keratinocyte differentiation. Visual analytics integration of gene information sources helped identify RAC1, a GTP binding protein, and TFRC, an iron uptake protein as prioritized arsenic-perturbed protein targets for biological processes leading to skin hyperpigmentation. RAC1 regulates the formation of dendrites that transfer melanin from melanocytes to neighboring keratinocytes. Increased melanocyte dendricity is correlated with hyperpigmentation. TFRC is a key determinant of the amount and location of iron in the epidermis. Aberrant TFRC expression could impair cutaneous iron metabolism leading to abnormal pigmentation seen in some humans exposed to arsenicals. The reported findings contribute to insights on how arsenic could impair the function of genes and biological pathways in epidermal cells. Finally, we developed visual analytics

  5. Differential effects of UV irradiation on nuclear retinoid receptor levels in cultured keratinocytes and melanocytes.

    PubMed

    Andersson, Eva; Rosdahl, Inger; Törmä, Hans; Vahlquist, Anders

    2003-10-01

    A major risk factor for skin cancer is UV irradiation, which not only damages DNA and other photosensitive compounds like vitamin A, but may also perturb cellular signaling, e.g. via the retinoid receptor system believed to be important for cancer protection. We used cultured normal human keratinocytes and melanocytes to examine the effects of UV irradiation on the expression of the predominant retinoid receptors in the human skin (RARalpha, RARgamma and RXRalpha) and the AP-1 protein c-Jun; mRNA levels were studied by real-time PCR and protein levels by Western blot. In keratinocytes, a single dose of UVB (50 mJ/cm2) caused a rapid drop in the expression of all three receptors (mRNA levels minus 35-50% after 4 h; protein levels minus 20-45% after 8 h), which was followed over the next 40 h by a variable response, leading to full normalization for RARalpha only. In contrast, the levels of c-Jun did not change significantly after UV exposure. In melanocytes, UVB caused a similar drop of the retinoid receptor levels as in keratinocytes but this was soon followed by an increased expression leading to a complete normalization of all receptor levels within 1-3 days. The c-Jun levels in melanocytes increased 1 day after UV exposure and remained high (plus 50%) thereafter. In both cell types, a approximately 3-fold increase in apoptosis (measured by DNA fragmentation) was observed 8-48 h after UVB irradiation. In conclusion, a depletion of vitamin A and retinoid receptors by UV irradiation, together with unchanged or even increased c-Jun levels, might seriously interfere with retinoid signaling and thus promote future tumor development, especially in keratinocytes. PMID:14705796

  6. Comparative cytogenetic characterization of primary canine melanocytic lesions using array CGH and fluorescence in situ hybridization.

    PubMed

    Poorman, Kelsey; Borst, Luke; Moroff, Scott; Roy, Siddharth; Labelle, Philippe; Motsinger-Reif, Alison; Breen, Matthew

    2015-06-01

    Melanocytic lesions originating from the oral mucosa or cutaneous epithelium are common in the general dog population, with up to 100,000 diagnoses each year in the USA. Oral melanoma is the most frequent canine neoplasm of the oral cavity, exhibiting a highly aggressive course. Cutaneous melanocytomas occur frequently, but rarely develop into a malignant form. Despite the differential prognosis, it has been assumed that subtypes of melanocytic lesions represent the same disease. To address the relative paucity of information about their genomic status, molecular cytogenetic analysis was performed on the three recognized subtypes of canine melanocytic lesions. Using array comparative genomic hybridization (aCGH) analysis, highly aberrant distinct copy number status across the tumor genome for both of the malignant melanoma subtypes was revealed. The most frequent aberrations included gain of dog chromosome (CFA) 13 and 17 and loss of CFA 22. Melanocytomas possessed fewer genome wide aberrations, yet showed a recurrent gain of CFA 20q15.3-17. A distinctive copy number profile, evident only in oral melanomas, displayed a sigmoidal pattern of copy number loss followed immediately by a gain, around CFA 30q14. Moreover, when assessed by fluorescence in situ hybridization (FISH), copy number aberrations of targeted genes, such as gain of c-MYC (80 % of cases) and loss of CDKN2A (68 % of cases), were observed. This study suggests that in concordance with what is known for human melanomas, canine melanomas of the oral mucosa and cutaneous epithelium are discrete and initiated by different molecular pathways. PMID:25511566

  7. A murine model for the development of melanocytic nevi and their progression to melanoma.

    PubMed

    Nasti, Tahseen H; Cochran, J Barry; Tsuruta, Yuko; Yusuf, Nabiha; McKay, Kristopher M; Athar, Mohammad; Timares, Laura; Elmets, Craig A

    2016-05-01

    Acquired melanocytic nevi are commonly found in sun exposed and unexposed human skin, but the potential for their transformation into invasive melanoma is not clear. Therefore, a mouse model of nevus initiation and progression was developed in C3H/HeN mice using a modified chemical carcinogenesis protocol. Nevi develop due to DNA damage initiated by dimethylbenz(a) anthracene (DMBA) followed by chronic promotion with 12-O-tetradecanoyl-phorbol-13-acetate (TPA). Dysplastic pigmented skin lesions appeared in 7-9 wk with 100% penetrance. Nests of melanocytic cells appeared in a subset of skin draining lymph nodes (dLN) by 25 wk, but not in age matched controls. Immunohistochemistry, real-time PCR, and flow cytometric analyses confirmed their melanocytic origin. Transformed cells were present in a subset of nevi and dLNs, which exhibited anchorage-independent growth, tumor development, and metastasis in nude mice. Approximately 50% of the cell lines contained H-Ras mutations and lost tumor suppressor p16(Ink4a) expression. While most studies of melanoma focus on tumor progression in transgenic mouse models where the mutations are present from birth, our model permits investigation of acquired mutations at the earliest stages of nevus initiation and promotion of nevus cell transformation. This robust nevus/melanoma model may prove useful for identifying genetic loci associated with nevus formation, novel oncogenic pathways, tumor targets for immune-prevention, screening therapeutics, and elucidating mechanisms of immune surveillance and immune evasion. © 2015 The Authors. Molecular Carcinogenesis, published by Wiley Periodicals, Inc. PMID:25788145

  8. Modelisation et commande des redresseurs triphases fonctionnant a haut rendement et a faible taux de distorsion harmonique: Application au redresseur triphase de vienne

    NASA Astrophysics Data System (ADS)

    Belhadj Youssef, Nesrine

    Les problemes de la qualite de l'onde electrique constituent l'une des preoccupations majeures des fournisseurs de l'energie et des organismes specialises en qualite d'energie. Ce sujet a gagne davantage d'ampleur avec l'utilisation ascendante des convertisseurs de l'energie electrique dans la majorite des applications industrielles et domestiques. Dans le cadre de cette these, on s'interesse plus particulierement au type des convertisseurs alternatif/continu, dont le fonctionnement adequat implique la parfaite regulation du bus DC de tension, l'attenuation des harmoniques de courants, la compensation de l'energie reactive et la maximisation du rendement energetique. Ces differents criteres doivent etre maintenus pour diverses conditions de fonctionnement, c'est-a-dire independamment des variations parametriques auxquelles le systeme peut etre sujet. Il s'avere donc indispensable d'adopter des techniques de commande efficaces, ce qui passe par une modelisation correcte du convertisseur. L'optimisation du nombre de capteurs dans le circuit est egalement un facteur cle a prendre en consideration.

  9. Conception des parametres des dupes auxiliaires pour ameliorer les performances electriques des isolateurs de poste dans des conditions de givrage

    NASA Astrophysics Data System (ADS)

    Ale-Emran, Sayyed Mahdi

    The optimized design of outdoor insulators that consider heavy icing and pollution conditions is a significant concern for the reliability of power networks. Based on field observations, the probability of flashover of EHV post insulators is higher than line insulators under the same heavy icing conditions. The flashover along the insulators is caused mainly by the presence of a water film on the ice surfaces (melting period) and partial arcs in ice-free zones (air gaps). One of the mitigation options is the use of booster sheds (BSs) to create air gaps along the iced insulator. A booster shed (BS) is a flexible c-shape device made of high-quality insulating materials. Since BSs are easy to use, they seem to be simpler alternatives to upgrading insulators to those designed for cold climate regions. Despite the promising results of BS applications, still an important work must be achieved to propose optimized design of BS configurations. This project aims to provide a generic design approach to the use of BSs by optimizing their main parameters (number, diameter, inclination angle, position, and permittivity) on post insulators under heavy icing conditions. This approach is based on analyzing previous BS tests in CEGELE, an improved hypothesis of BS effects, numerical analysis using commercial software (e.g. Comsol Multiphysics(TM), Matlab, and Minitab), geometric modeling of ice-covered post insulator with BSs, and finally experimental validation tests. The improved hypothesis states that the major effect of BSs is the creation of air gaps and their minor effect is the increase in dry arcing distance. Moreover, among total length of the air gaps, dry arcing distance, and total ice-free leakage distance (IFLDtot), the IFLDtot is a good indicator to quantify the BS effects on standard post insulators. Simulation analyses of BS configurations during the melting period demonstrate that the optimized relative permittivity of BS is an arbitrary value in its feasible variation range (2-15). The proper positions of BSs close to the HV electrode should be determined based on the probability of electrical breakdown. In contrast, the positions close to the ground electrode are determined based on ice-bridging effect. The geometric model and Taguchi method analysis show that the optimized value of BS inclination angle is equal to the upper shed angle of the insulator. Also, it indicates that generally the maximum feasible values for diameter and number of BSs are the best options. The feasibility in this regard, depends mainly on the minimum required distances between BSs as well as the mechanical forces of heavy ice and strong wind that may deform BSs. PVC sheet was deemed an effective solution for fabricating BS prototypes to perform the final validation tests. The experimental tests completely confirmed the improved hypothesis, the effectiveness of the geometric model, and the simulation analysis.

  10. Application de l’analyse des séries chronologiques à la projection d’effectifs de population scolaire par la méthode des composantes

    PubMed Central

    Smith, Herbert L.

    2016-01-01

    Cet article veut montrer qu’on peut réécrire des modèles démographiques en vue de réaliser des projections par cohorte, en les transposant dans un modèle économétrique vecteur autoré-gressif (VAR). De cette façon, la méthode des composantes se dote d’un cadre stochastique qui étend son envergure. Le potentiel de cette perspective est illustré à travers l’exemple d’une projection d’effectifs de population scolaire. Il met en valeur une série d’équations qui permet de vérifier la validité de plusieurs choix de modélisations habituellement utilisées dans le domaine de la prévision. PMID:27346921

  11. A recurrent melanocytic nevus phenomenon in the setting of Hailey-Hailey disease.

    PubMed

    Noor, Omar; Elston, Dirk; Flamm, Alexandra; Hall, Lawrence D; Cha, Jisun

    2015-08-01

    Atypical acquired melanocytic nevi in patients with epidermolysis bullosa (EB) have been referred to as EB nevi and are considered to be a type of recurrent nevus with atypical but distinctive histopathologic findings. Herein, we describe an atypical nevus in a patient with Hailey-Hailey disease with different histopathologic findings from EB nevi because of presumably different pathogenesis. It is important to be aware that the recurrent nevi phenomenon can be seen in acantholytic conditions as well as blistering disorders, given these lesions may clinically resemble melanoma. PMID:25950447

  12. [The congenital melanocytic nevi of the face in child: What's new?].

    PubMed

    Captier, G

    2015-09-01

    Congenital melanocytic nevi of the face are a frequent reason for consultation in paediatric plastic surgery. Usually of small size, they raise a complex problem of reconstruction when they are large and giant. The indication of excision is generally stated on aesthetic criteria whereas the risk of melanoma is especially important in the giant nevi. Simple suture, full thickness skin graft and expanded skin flaps are the techniques of choice. The treatment must be carried out precociously, follow a surgical planning, respect the aesthetic units of the face and the periorificial areas, adapt to the age of the child and bring psychological benefit to the child. PMID:26189003

  13. Nuclear hormone receptor functions in keratinocyte and melanocyte homeostasis, epidermal carcinogenesis and melanomagenesis

    PubMed Central

    Hyter, Stephen; Indra, Arup K

    2013-01-01

    Skin homeostasis is maintained, in part, through regulation of gene expression orchestrated by type II nuclear hormone receptors in a cell and context specific manner. This group of transcriptional regulators is implicated in various cellular processes including epidermal proliferation, differentiation, permeability barrier formation, follicular cycling and inflammatory responses. Endogenous ligands for the receptors regulate actions during skin development and maintenance of tissue homeostasis. Type II nuclear receptor signaling is also important for cellular crosstalk between multiple cell types in the skin. Overall, these nuclear receptors are critical players in keratinocyte and melanocyte biology and present targets for cutaneous disease management. PMID:23395795

  14. A Case of Intradermal Melanocytic Nevus with Ossification (Nevus of Nanta)

    PubMed Central

    Lee, Young Bok; Lee, Kyung Ho

    2008-01-01

    A 49-year-old woman presented with a 30-year history of asymptomatic plaque on her right temple. The histological examination revealed nests of nevus cells throughout the entire dermis. Bony spicules were seen just beneath the nevus cell nests in the lower dermis. Cutaneous ossification is an unusual event. Herein, we present a case of intradermal melanocytic nevus with unusual ossification (nevus of Nanta). To the best of our knowledge, this is the first such case report in the Korean literature. PMID:27303191

  15. Significance of the Melanocortin 1 and Endothelin B Receptors in Melanocyte Homeostasis and Prevention of Sun-Induced Genotoxicity

    PubMed Central

    Swope, Viki B.; Abdel-Malek, Zalfa A.

    2016-01-01

    The membrane bound melanocortin 1 receptor (MC1R), and the endothelin B receptor (ENDBR) are two G-protein coupled receptors that play important roles in constitutive regulation of melanocytes and their response to ultraviolet radiation (UVR), the main etiological factor for melanoma. The human MC1R is a Gs protein-coupled receptor, which is activated by its agonists α-melanocyte stimulating hormone (α-melanocortin; α-MSH) and adrenocorticotropic hormone (ACTH). The ENDBR is a Gq coupled-receptor, which is activated by Endothelin (ET)-3 during embryonic development, and ET-1 postnatally. Pigmentation and the DNA repair capacity are two major factors that determine the risk for melanoma. Activation of the MC1R by its agonists stimulates the synthesis of eumelanin, the dark brown photoprotective pigment. In vitro studies showed that α-MSH and ET-1 interact synergistically in the presence of basic fibroblast growth factor to stimulate human melanocyte proliferation and melanogenesis, and to inhibit UVR-induced apoptosis. An important function of the MC1R is reduction of oxidative stress and activation of DNA repair pathways. The human MC1R is highly polymorphic, and MC1R variants, particularly those that cause loss of function of the expressed receptor, are associated with increased melanoma risk independently of pigmentation. These variants compromise the DNA repair and antioxidant capacities of human melanocytes. Recently, activation of ENDBR by ET-1 was reported to reduce the induction and enhance the repair of UVR-induced DNA photoproducts. We conclude that α-MSH and ET-1 and their cognate receptors MC1R and ENDBR reduce the risk for melanoma by maintaining genomic stability of melanocytes via modulating the DNA damage response to solar UVR. Elucidating the response of melanocytes to UVR should improve our understanding of the process of melanomagenesis, and lead to effective melanoma chemoprevention, as well as therapeutic strategies. PMID:27582758

  16. Dynamic assembly of chromatin complexes during cellular senescence: implications for the growth arrest of human melanocytic nevi

    PubMed Central

    Bandyopadhyay, Debdutta; Curry, Jonathan L; Lin, Qiushi; Richards, Hunter W; Chen, Dahu; Hornsby, Peter J; Timchenko, Nikolai A; Medrano, Estela E

    2007-01-01

    The retinoblastoma (RB)/p16INK4a pathway regulates senescence of human melanocytes in culture and oncogene-induced senescence of melanocytic nevi in vivo. This senescence response is likely due to chromatin modifications because RB complexes from senescent melanocytes contain increased levels of histone deacetylase (HDAC) activity and tethered HDAC1. Here we show that HDAC1 is prominently detected in p16INK4a-positive, senescent intradermal melanocytic nevi but not in proliferating, recurrent nevus cells that localize to the epidermal/dermal junction. To assess the role of HDAC1 in the senescence of melanocytes and nevi, we used tetracycline-based inducible expression systems in cultured melanocytic cells. We found that HDAC1 drives a sequential and cooperative activity of chromatin remodeling effectors, including transient recruitment of Brahma (Brm1) into RB/HDAC1 mega-complexes, formation of heterochromatin protein 1β (HP1β)/SUV39H1 foci, methylation of H3-K9, stable association of RB with chromatin and significant global heterochromatinization. These chromatin changes coincide with expression of typical markers of senescence, including the senescent-associated β-galactosidase marker. Notably, formation of RB/HP1β foci and early tethering of RB to chromatin depends on intact Brm1 ATPase activity. As cells reached senescence, ejection of Brm1 from chromatin coincided with its dissociation from HP1β/RB and relocalization to protein complexes of lower molecular weight. These results provide new insights into the role of the RB pathway in regulating cellular senescence and implicate HDAC1 as a likely mediator of early chromatin remodeling events. PMID:17578512

  17. MMP13 mediates cell cycle progression in melanocytes and melanoma cells: in vitro studies of migration and proliferation

    PubMed Central

    2010-01-01

    Background Melanoma cells are usually characterized by a strong proliferative potential and efficient invasive migration. Among the multiple molecular changes that are recorded during progression of this disease, aberrant activation of receptor tyrosine kinases (RTK) is often observed. Activation of matrix metalloproteases goes along with RTK activation and usually enhances RTK-driven migration. The purpose of this study was to examine RTK-driven three-dimensional migration of melanocytes and the pro-tumorigenic role of matrix metalloproteases for melanocytes and melanoma cells. Results Using experimental melanocyte dedifferentiation as a model for early melanomagenesis we show that an activated EGF receptor variant potentiates migration through three-dimensional fibrillar collagen. EGFR stimulation also resulted in a strong induction of matrix metalloproteases in a MAPK-dependent manner. However, neither MAPK nor MMP activity were required for migration, as the cells migrated in an entirely amoeboid mode. Instead, MMPs fulfilled a function in cell cycle regulation, as their inhibition resulted in strong growth inhibition of melanocytes. The same effect was observed in the human melanoma cell line A375 after stimulation with FCS. Using sh- and siRNA techniques, we could show that MMP13 is the protease responsible for this effect. Along with decreased proliferation, knockdown of MMP13 strongly enhanced pigmentation of melanocytes. Conclusions Our data show for the first time that growth stimuli are mediated via MMP13 in melanocytes and melanoma, suggesting an autocrine MMP13-driven loop. Given that MMP13-specific inhibitors are already developed, these results support the evaluation of these inhibitors in the treatment of melanoma. PMID:20667128

  18. MicroRNA-27a-3p Inhibits Melanogenesis in Mouse Skin Melanocytes by Targeting Wnt3a.

    PubMed

    Zhao, Yuanyuan; Wang, Pengchao; Meng, Jinzhu; Ji, Yuankai; Xu, Dongmei; Chen, Tianzhi; Fan, Ruiwen; Yu, Xiuju; Yao, Jianbo; Dong, Changsheng

    2015-01-01

    MicroRNAs (miRNAs) play an essential role in the regulation of almost all the biological processes, including melanogenesis. MiR-27a-3p is nearly six times higher in white alpaca skin compared to brown skin, which indicates that miR-27a-3p may be a candidate regulator for melanogenesis. Wnt3a plays an important role in promoting melanoblasts to differentiate into melanocytes and melanogenesis. To confirm the function of miR-27a-3p to melanogenesis in mammals, miR-27a-3p mimic, inhibitor and their negative control were transfected into mouse melanocytes. As a result, miR-27a-3p inhibits melanogenesis by repressing Wnt3a at post-transcriptional level. A significant decrease in Wnt3a luciferase activity was observed in 293T cells co-transfected with the matched luciferase reporter vector and pre-miR-27a. Furthermore, the presence of exogenous miR-27a-3p significantly decreased Wnt3a protein expression rather than mRNA and reduced β-catenin mRNA levels in melanocytes. The over-expression of miR-27a-3p significantly increased the melanin content of melanocytes. However, miR-27a-3p inhibitor performs an opposite effect on melanogenesis. Wnt3a is one target of miR-27a-3p. MiR-27a-3p could inhibit Wnt3a protein amount by post-transcriptional regulation and melanogenesis in mouse melanocytes. Previous studies reported that Wnt3a promoted melanogenensis in mouse melanocytes. Thus, miR-27-3p inhibits melanogenesis by repressing Wnt3a protein expression. PMID:26006230

  19. MicroRNA-27a-3p Inhibits Melanogenesis in Mouse Skin Melanocytes by Targeting Wnt3a

    PubMed Central

    Zhao, Yuanyuan; Wang, Pengchao; Meng, Jinzhu; Ji, Yuankai; Xu, Dongmei; Chen, Tianzhi; Fan, Ruiwen; Yu, Xiuju; Yao, Jianbo; Dong, Changsheng

    2015-01-01

    MicroRNAs (miRNAs) play an essential role in the regulation of almost all the biological processes, including melanogenesis. MiR-27a-3p is nearly six times higher in white alpaca skin compared to brown skin, which indicates that miR-27a-3p may be a candidate regulator for melanogenesis. Wnt3a plays an important role in promoting melanoblasts to differentiate into melanocytes and melanogenesis. To confirm the function of miR-27a-3p to melanogenesis in mammals, miR-27a-3p mimic, inhibitor and their negative control were transfected into mouse melanocytes. As a result, miR-27a-3p inhibits melanogenesis by repressing Wnt3a at post-transcriptional level. A significant decrease in Wnt3a luciferase activity was observed in 293T cells co-transfected with the matched luciferase reporter vector and pre-miR-27a. Furthermore, the presence of exogenous miR-27a-3p significantly decreased Wnt3a protein expression rather than mRNA and reduced β-catenin mRNA levels in melanocytes. The over-expression of miR-27a-3p significantly increased the melanin content of melanocytes. However, miR-27a-3p inhibitor performs an opposite effect on melanogenesis. Wnt3a is one target of miR-27a-3p. MiR-27a-3p could inhibit Wnt3a protein amount by post-transcriptional regulation and melanogenesis in mouse melanocytes. Previous studies reported that Wnt3a promoted melanogenensis in mouse melanocytes. Thus, miR-27-3p inhibits melanogenesis by repressing Wnt3a protein expression. PMID:26006230

  20. Significance of the Melanocortin 1 and Endothelin B Receptors in Melanocyte Homeostasis and Prevention of Sun-Induced Genotoxicity.

    PubMed

    Swope, Viki B; Abdel-Malek, Zalfa A

    2016-01-01

    The membrane bound melanocortin 1 receptor (MC1R), and the endothelin B receptor (ENDBR) are two G-protein coupled receptors that play important roles in constitutive regulation of melanocytes and their response to ultraviolet radiation (UVR), the main etiological factor for melanoma. The human MC1R is a Gs protein-coupled receptor, which is activated by its agonists α-melanocyte stimulating hormone (α-melanocortin; α-MSH) and adrenocorticotropic hormone (ACTH). The ENDBR is a Gq coupled-receptor, which is activated by Endothelin (ET)-3 during embryonic development, and ET-1 postnatally. Pigmentation and the DNA repair capacity are two major factors that determine the risk for melanoma. Activation of the MC1R by its agonists stimulates the synthesis of eumelanin, the dark brown photoprotective pigment. In vitro studies showed that α-MSH and ET-1 interact synergistically in the presence of basic fibroblast growth factor to stimulate human melanocyte proliferation and melanogenesis, and to inhibit UVR-induced apoptosis. An important function of the MC1R is reduction of oxidative stress and activation of DNA repair pathways. The human MC1R is highly polymorphic, and MC1R variants, particularly those that cause loss of function of the expressed receptor, are associated with increased melanoma risk independently of pigmentation. These variants compromise the DNA repair and antioxidant capacities of human melanocytes. Recently, activation of ENDBR by ET-1 was reported to reduce the induction and enhance the repair of UVR-induced DNA photoproducts. We conclude that α-MSH and ET-1 and their cognate receptors MC1R and ENDBR reduce the risk for melanoma by maintaining genomic stability of melanocytes via modulating the DNA damage response to solar UVR. Elucidating the response of melanocytes to UVR should improve our understanding of the process of melanomagenesis, and lead to effective melanoma chemoprevention, as well as therapeutic strategies. PMID:27582758

  1. L'atteinte osseuse dans le sarcome de Kaposi classique et agressif: à propos d'un cas

    PubMed Central

    Sbiyaa, Mouhcine; El Alaoui, Adil; El Bardai, Mohammed; Mezzani, Amine; Lahrach, Kamal; Marzouki, Amine; Boutayeb, Fawzi

    2016-01-01

    Le sarcome de Kaposi classique est une tumeur rare multifocale d'origine des cellules endothéliales vasculaires à caractère évolutif progressif et peu maligne. L'atteinte viscérale dans le sarcome de kaposi est parfois observée chez les patients VIH positif par contre la dissémination tumorale dans les ganglions lymphatiques viscérales dans le SK classique reste très rare. On rapporte un cas rare de sarcome de kaposi classique agressif de la main avec une évolution rapide et destructive. PMID:27347285

  2. Reconstruction de la surface de Fermi dans l'etat normal d'un supraconducteur a haute Tc: Une etude du transport electrique en champ magnetique intense

    NASA Astrophysics Data System (ADS)

    Le Boeuf, David

    Des mesures de resistance longitudinale et de resistance de Hall en champ magnetique intense transverse (perpendiculaire aux plans CuO2) ont ete effectuees au sein de monocristaux de YBa2Cu3Oy (YBCO) demacles, ordonnes et de grande purete, afin d'etudier l'etat fondamental des supraconducteurs a haute Tc dans le regime sous-dope. Cette etude a ete realisee en fonction du dopage et de l'orientation du courant d'excitation J par rapport a l'axe orthorhombique b de la structure cristalline. Les mesures en champ magnetique intense revelent par suppression de la supraconductivite des oscillations magnetiques des resistances longitudinale et de Hall dans YBa2Cu 3O6.51 et YBa2Cu4O8. La conformite du comportement de ces oscillations quantiques au formalisme de Lifshitz-Kosevich, apporte la preuve de l'existence d'une surface de Fermi fermee a caractere quasi-2D, abritant des quasiparticules coherentes respectant la statistique de Fermi-Dirac, dans la phase pseudogap d'YBCO. La faible frequence des oscillations quantiques, combinee avec l'etude de la partie monotone de la resistance de Hall en fonction de la temperature indique que la surface de Fermi d'YBCO sous-dope comprend une petite poche de Fermi occupee par des porteurs de charge negative. Cette particularite de la surface de Fermi dans le regime sous-dope incompatible avec les calculs de structure de bande est en fort contraste avec la structure electronique presente dans le regime surdope. Cette observation implique ainsi l'existence d'un point critique quantique dans le diagramme de phase d'YBCO, au voisinage duquel la surface de Fermi doit subir une reconstruction induite par l'etablissement d'une brisure de la symetrie de translation du reseau cristallin sous-jacent. Enfin, l'etude en fonction du dopage de la resistance de Hall et de la resistance longitudinale en champ magnetique intense suggere qu'un ordre du type onde de densite (DW) est responsable de la reconstruction de la surface de Fermi. L'analogie de

  3. Atypical dermoscopic presentation of an acral congenital melanocytic nevus in an adult: parallel ridge pattern and its histologic correlation

    PubMed Central

    Roldán-Marín, Rodrigo; González-de-Cossío-Hernández, Ana Cecilia; Lammoglia-Ordiales, Lorena; Martínez-Luna, Eduwiges; Toussaint-Caire, Sonia; Ferrara, Gerardo

    2015-01-01

    Acral melanoma is the most frequent subtype in the Asian and Mexican mestizo populations. Dermoscopy is a noninvasive diagnostic technique that helps the differential diagnosis of pigmented skin lesions on acral volar skin. We, herein, present a case of acral congenital melanocytic nevus with a parallel ridge dermoscopic pattern. Since the parallel ridge pattern in a melanocytic lesion of the acral skin is classically ascribed to melanoma, the present case can be definitely labeled as “atypical” and worth of being elucidated in its histopathological correlates. PMID:26693085

  4. Enseignement des langues et theories d'acquisition Sprachunterricht unde Spracherwerbstheorien. (Language Teaching and Acquisition Theories).

    ERIC Educational Resources Information Center

    Schwarz, Alexander, Ed.

    1996-01-01

    This collection of articles on language teaching and language acquisition theories includes: "Enseignement des langues et theories de l'acquisition. Introduction au colloque" ("Language Teaching and Theories of Acquisition. Introduction to the Colloquium") (Rene Richterich); "Apprendre une langue dans l'interaction verbale" ("Language Learning in…

  5. Fluctuations quantiques et instabilites structurales dans les conducteurs a basse dimensionalite

    NASA Astrophysics Data System (ADS)

    Dikande, Alain Moise

    Un engouement particulier s'est manifeste ces dernieres annees pour les systemes electroniques fortement correles, ce en rapport avec l'immense richesse de leurs proprietes physiques. En general, ces proprietes sont induites par la presence d'interactions entre electrons qui, combinees a la structure du reseau moleculaire, donnent parfois lieu a une tres grande variete de phases electroniques et structurales ayant des incidences directes sur les phenomenes de transport dans ces materiaux. Les systemes electroniques couples a un reseau moleculaire et designes systemes electron-phonon font partie de cette classe de materiaux qui ont recemment capte l'attention, en raison notamment de la competition entre plusieurs echelles d'energie dans un environnement caracterise par une forte anisotropie cristalline et une dynamique moleculaire assez importante. En effet, en plus des proprietes electroniques et structurales particulieres la dimensionalite de ces systemes contribue egalement a leur richesse. Ainsi, une tres forte anisotropie structurale peut rehausser de facon considerable l'importance des interactions entre electrons et entre molecules constituant le reseau au point ou la physique du systeme soit regie par de tres fortes fluctuations. Ce dernier contexte est devenu un domaine a part de la physique des systemes fortement correles, a savoir celui des les phenomenes critiques quantiques . Parmi les systemes electron-phonon, on retrouve les composes inorganique KCP et organique TTF-TCNQ decouverts durant les annees 70, et explores en profondeur a cause de leur tendance vers une instabilite du type onde de densite de charge a basse temperature. Ces composes, en general designes systemes de Peierls en reference a l'instabilite de leurs structures electroniques regie par le reseau moleculaire, ont recemment connu un regain d'interet a la lumiere des nouveaux developpements dans les techniques de caracterisation des structures electroniques ainsi que sur le plan de

  6. Melanocytic nevi with special features: clinical-dermoscopic and reflectance confocal microscopic-findings.

    PubMed

    Larre Borges, A; Zalaudek, I; Longo, C; Dufrechou, L; Argenziano, G; Lallas, A; Piana, S; Moscarella, E

    2014-07-01

    Histopathology is considered the 'gold' standard for the diagnosis and classification of melanocytic nevi, but the widespread use of in vivo diagnostic technologies such as dermoscopy and reflectance confocal microscopy (RCM), has enriched profoundly the knowledge regarding the morphological variability in nevi. This is because most morphological observations made via these in vivo tools are closely correlated with features seen in histopathology. Dermoscopy has allowed for a more detailed classification of nevi. As such, dermoscopy identifies four main morphologic groups (i.e. globular, reticular, starburst and structureless blue nevi), one group of nevi located at special body sites (i.e. face, acral, nail) and one group of nevi with special features. This latter category consists of nevi of the former categories, which are typified by peculiar clinical-histopathological findings. They can be subdivided into 'melanoma simulators' including combined nevi, recurrent nevi and sclerosing nevus with pseudomelanomatous features, 'targetoid' nevi (i.e. halo, cockade, irritated targetoid haemosiderotic and eczematous nevus) and uncommon histopathological variants such as desmoplastic, white dysplastic or ballon cell nevus. While the dermoscopic and RCM patterns of the former categories have been studied in detail, little is currently known about the clinical morphology of the heterogeneous group of 'special' nevi. In this article, we describe the clinical, dermoscopic and RCM features of 'special' nevi and review the current literature on this group of melanocytic proliferations. PMID:24171788

  7. A distinctive melanocytic lesion associated with melanoma-prone dysplastic naevus syndrome: the hybrid naevus.

    PubMed

    Schubert, C; Parwaresch, R; Rudolph, P

    2001-02-01

    Clinically and histologically, the concept of dysplastic nevi remains controversial. To elaborate more precise criteria for the nevi of patients with dysplastic naevus syndrome (DNS), we examined 58 nevi from seven DNS patients who developed one or several malignant melanomas. Clinical presentation and histomorphology were evaluated, and immunohistochemistry was performed using proliferation marker Ki-S5 and antibody DO-7 to the p53 protein. Sixty nevi from individuals without history of melanoma served as controls. Of the DNS nevi, 21 (36.2%) exhibited no morphological particularities. The remaining 37 nevi presented distinctive histological features consisting of a slight epidermal acanthosis, spitzoid vertically oriented nests of dyscohesive nevus cells, and single-standing atypical melanocytes in the basal cell layer of the epidermis. Immunohistochemical analysis revealed an average proliferation index of 2.5%, which significantly surpassed the mean growth fraction of conventional dysplastic nevi (<1%). No increase in p53 expression was observed. Characteristically, active proliferation was found in junctional single-standing melanocytes with or without nuclear atypia rather than in nest-shaped compounds. In conclusion, certain moles of patients with DNS possess distinctive features. The newly characterized criteria may provide a basis for the diagnosis of DNS and might help to identify patients at increased risk for malignant melanoma by examination of a single biopsy. PMID:11253119

  8. Effect of saucerneol D on melanin production in cAMP-elevated melanocytes.

    PubMed

    Yun, Ji Young; Roh, Eunmiri; Son, Jong-Keun; Lee, Seung Ho; Seo, Chang-Seob; Hwang, Bang Yeon; Han, Sang-Bae; Kim, Youngsoo

    2011-08-01

    Intracellular cAMP stimulates microphthalmia-associated transcription factor (MITF) induction in melanocytes through cAMP-responsive element binding protein (CREB), which plays a pivotal role in the gene expression of tyrosinase for melanin biosynthesis. In the present study, saucerneol D as a lignan constituent of Saururus chinensis (Saururaceae family) efficiently inhibited melanin production with IC(50) values of 188-297 nM in B16 melanoma cells stimulated with α-melanocyte stimulating hormone (α-MSH) or other cAMP elevators. Moreover, saucerneol D down-regulated α-MSH-induced gene expression of tyrosinase at the transcription level in B16 cells, but it did not directly inhibit the catalytic activity of cell-free tyrosinase. As to the molecular basis of hypopigmenting action, saucerneol D inhibited α-MSH-induced phosphorylation of CREB in the cells, and sequentially suppressed MITF induction. Taken together, this study provides saucerneol D down-regulated the gene expression of tyrosinase, resulting in the inhibition of cAMP-induced melanin biosynthesis, and suggests pharmacological potential of the lignan structure in skin hyperpigmentation. PMID:21910056

  9. Modulation of Melanogenesis by Heme Oxygenase-1 via p53 in Normal Human Melanocytes

    PubMed Central

    Lim, Hee-Sun; Jin, Suna

    2016-01-01

    As a key regulator of melanogenesis, p53 controls microphthalmia-associated transcription factor (MITF) and tyrosinase expression. The anti-oxidant enzyme heme oxygenase-1 (HO-1) is induced by various forms of cellular stress and diverse oxidative stimuli. However, few studies have examined the role of HO-1 in melanogenesis. Therefore, the aim of this study was to determine the role of HO-1 in melanogenesis and the mechanism underlying this relationship. Cultures of normal human melanocytes were treated with the HO-1 inducer cobalt protoporphyrin (CoPP) or the HO-1 inhibitor zinc protoporphyrin (ZnPP). We then measured the melanin content of the cells. Additional analyses consisted of Western blotting and RT-PCR. The results showed that the cellular melanin content was increased by CoPP and decreased by ZnPP. The Western blot and RT-PCR analyses showed that CoPP increased p53, MITF and tyrosinase levels, and ZnPP reduced all of them. The knockdown of p53 by siRNA transfection was followed by large decreases in the expression levels of p53, MITF and tyrosinase at 3 h of transfection. The presence of CoPP or ZnPP had no significant increased or decreased effects on MITF and tyrosinase levels from 15 h in the siRNA transfectants. Our results suggest that HO-1 modulates melanogenesis in human melanocytes via a p53-dependent pathway. PMID:26865999

  10. Controversies in the Evaluation and Management of Atypical Melanocytic Proliferations in Children, Adolescents, and Young Adults

    PubMed Central

    Reed, Damon; Kudchadkar, Ragini; Zager, Jonathan S.; Sondak, Vernon K.; Messina, Jane L.

    2015-01-01

    The rising incidence of melanoma in children has brought increased attention to the clinical and pathologic diagnosis of pigmented lesions in the pediatric age group. Although melanoma in infancy and early childhood is often associated with large congenital nevi, in older children and teenagers it is most often sporadic, occurring in patients with a low skin phototype and substantial sun exposure. The rarity of this potentially fatal disorder demands astute clinical attention and a high index of suspicion for atypical lesions in pediatric patients. The challenges include the difficult decision of whether to biopsy and an often equivocal pathologic diagnosis. These diagnostically challenging and equivocal lesions lead to a degree of uncertainty regarding additional workup, prognosis, potential therapy, and follow-up plans. Consultation with a specialty dermatopathologist can be very helpful, and advanced molecular diagnostic techniques may be used in selected circumstances. Although still controversial, good evidence exists to justify a role for sentinel lymph node biopsy. Patients with atypical melanocytic proliferations have a high rate of positive sentinel lymph nodes; however, their outcomes are clearly better than in similarly staged adults with conventional melanoma. With the multiple variables involved and the relative lack of prospectively derived evidence, clinical decision-making is challenging and patients and families may experience considerable stress. This article provides data and weighs the pros and cons of a rationale for decision-making in pediatric and young adult patients with diagnostically challenging melanocytic lesions. PMID:23744867

  11. Patterns in melanocytic lesions: impact of the geometry on growth and transport inside the epidermis

    PubMed Central

    Balois, Thibaut; Chatelain, Clément; Ben Amar, Martine

    2014-01-01

    In glabrous skin, nevi and melanomas exhibit pigmented stripes during clinical dermoscopic examination. They find their origin in the basal layer geometry which periodically exhibits ridges, alternatively large (limiting ridges) and thin (intermediate ridges). However, nevus and melanoma lesions differ by the localization of the pigmented stripes along furrows or ridges of the epidermis surface. Here, we propose a biomechanical model of avascular tumour growth which takes into account this specific geometry in the epidermis where both kinds of lesions first appear. Simulations show a periodic distribution of tumour cells inside the lesion, with a global contour stretched out along the ridges. In order to be as close as possible to clinical observations, we also consider the melanin transport by the keratinocytes. Our simulations show that reasonable assumptions on melanocytic cell repartition in the ridges favour the limiting ridges of the basal compared with the intermediate ones in agreement with nevus observations but not really with melanomas. It raises the question of cell aggregation and repartition of melanocytic cells in acral melanomas and requires further biological studies of these cells in situ. PMID:24872499

  12. Non psammomatous melanocytic schwannoma presenting as a subcutaneous nodule: A rare presentation of a rare lesion

    PubMed Central

    Gulati, Harveen Kaur; Joshi, Avinash R.; Anand, Mani; Deshmukh, S. D.

    2016-01-01

    Melanocytic schwannoma (MS) is an extremely rare soft tissue tumor accounting for less than 1% of all primitive nerve sheath tumors, with a predilection for spinal nerve involvement. To date, only 20 cases of cutaneous/subcutaneous MS have been described in literature. Here, we describe a case of MS presenting as a subcutaneous nodule in a 22-year-old male in right thigh. On examination, the nodule measured 2.5 × 2.0 × 1.5 cm with overlying skin showing a bluish hue and an ulcer. With a preoperative diagnosis of hemangioma, the patient was taken up for wide local excision and was diagnosed as a case of non psammomatous melanocytic schwannoma based on clinical, histological, and immunohistochemical studies. Immunohistochemistry revealed positivity with S-100, HMB-45, and Melan A with pericellular Laminin positivity. Carney's syndrome was ruled out. MS needs to be differentiated from other pigmented lesions like pigmented neurofibroma, Bednar tumor, cellular blue neavus, and especially malignant melanoma, which has an obvious ominous prognosis. Since MS can show unpredictable behavior especially in absence of overt malignant features, a long term follow up with or without radiotherapy is recommended. PMID:27366278

  13. Papillary thyroid cancer in a young woman affected by giant congenital melanocytic nevus, ultrasound diagnosis.

    PubMed

    Manganaro, L; Onesti, M G; Sergi, M E; Vinci, V; Maruccia, M; Soda, G; Marini, M

    2011-01-01

    Data literatures report numerous association between giant congenital nevus and development alteration; only two cases describe its coexistence with thyroid disorders. However, we report the association of papillary thyroid cancer and giant congenital nevus. Papillary thyroid cancer is the most common differentiated thyroid cancer and has high prevalence in young women. In this paper we report: the case of a 18 years-old woman, affected by giant congenital melanocytic nevus on her back, who came to our observation because of one month of fever and increased volume of latero-cervical lymph nodes. Negative serologic tests allowed us to exclude lymphoma and mononucleosis. Because of the high risk (6%) that giant congenital melanocytic nevi could transform into malignant melanoma, we performed an ultrasound examination (US) of the cervical lymph nodes. The examination extended to the thyroid gland enabled us to visualize the same parenchyma alteration in both thyroid gland and lymph nodes. At last, fine-needle percoutaneus aspiration on thyroid lesion confirmed the presence of papillary carcinoma. In our case, thank to the optimal visualization of the parenchyma structure, US was diriment allowing a diagnosis of primitive thyroid lesion with an involvement of all lymph nodes in the neck. This findings legitimate the role of US as an accurate, noninvasive, radiation free and low-cost imaging technique in detecting differential diagnosis in the cervical lymphadenopathy, as well in preoperative staging thyroid carcinoma. PMID:22041799

  14. Expression of fibronectin, fibronectin isoforms and integrin receptors in melanocytic lesions.

    PubMed Central

    Natali, P. G.; Nicotra, M. R.; Di Filippo, F.; Bigotti, A.

    1995-01-01

    In vitro studies have demonstrated that fibronectin (FN) can deliver a mitogenic signal to quiescent human melanoma cells and that the alpha 5/beta 1-integrin receptor mediates this stimulus. In view of this finding we have analysed the in vivo expression of FN, and of ED-A and ED-B FN isoforms, in benign and malignant lesions of melanocyte origin. In the same specimens the expression of fibronectin integrin receptors was evaluated. The results demonstrate that, while detection of FN does not correlate with transformation and tumour progression, the expression of the two isoforms is associated with transformation and that only the ED-A variant is found in metastases. Integrin phenotyping disclosed that alpha 3/beta 1 expression is associated with tumour progression, alpha v/beta 3 is a marker of transformation, alpha 4 is rarely expressed and alpha 5 is expressed by about 50% and 30% of the primary and metastatic lesions respectively. Taken together, the results of this study demonstrate that transformation and tumour progression of the melanocyte lineage are associated with modulation of expression of FN isoforms and FN integrin receptors. Furthermore, the expression of alpha 5-integrin in a considerable percentage of primary and metastatic lesions indicates that FN may deliver a proliferative stimulus to melanoma cells in vivo. Images Figure 1 PMID:7779718

  15. La prévention des infections par le virus respiratoire syncytial

    PubMed Central

    Robinson, JL

    2011-01-01

    RÉSUMÉ L’infection par le virus respiratoire syncytial (VRS) est la principale cause d’infections des voies respiratoires inférieures chez les jeunes enfants. Le palivizumab, un anticorps monoclonal anti-VRS, réduit le taux d’hospitalisation des enfants à haut risque mais est très coûteux. Le présent document de principes remplace les trois précédents documents de principes de la Société canadienne de pédiatrie sur le sujet et est mis à jour principalement pour traiter des récentes modifications aux lignes directrices de l’American Academy of Pediatrics dans le contexte canadien. Il contient une analyse des publications ainsi que des recommandations au sujet de l’utilisation du palivizumab chez les enfants à haut risque

  16. Approche à l’égard des nouveaux anticoagulants oraux en pratique familiale

    PubMed Central

    Douketis, James; Bell, Alan David; Eikelboom, John; Liew, Aaron

    2014-01-01

    Résumé Objectif Comparer les caractéristiques principales des nouveaux anticoagulants oraux (NACO), soit le dabigatran, le rivaroxaban et l’apixaban, et répondre aux questions qui font surface lors de la comparaison de ces agents. Qualité des données Une recherche dans PubMed a été effectuée afin de relever les études cliniques récentes (de janvier 2008 à la semaine 32 de 2013) portant sur l’emploi des NACO pour la prévention des AVC dans les cas de fibrillation auriculaire (FA) et pour le traitement de la thromboembolie veineuse aiguë. Message principal Selon 3 essais d’envergure, tous les NACO sont au moins aussi efficaces que la warfarine dans la prévention des AVC chez les patients atteints d’une FA non valvulaire, et au moins aussi sûrs pour ce qui est du risque de saignement. Des méta-analyses de ces essais ont montré que, comparativement au traitement par la warfarine, les NACO avaient réduit la mortalité totale, la mortalité d’origine cardiovasculaire et les saignements intracrâniens, et était aussi ressortie une tendance vers la réduction des saignements généraux. Du côté pratique, les avantages des NACO par rapport à la warfarine sont : posologie orale fixe uniquotidienne ou biquotidienne sans devoir surveiller la coagulation et peu d’interactions connues ou définies avec d’autres médicaments ou des aliments. Les désavantages potentiels des NACO sont notamment un risque de saignement qui serait accru chez les patients de plus de 75 ans, une hausse des saignements gastro-intestinaux majeurs avec des doses élevées de dabigatran, une hausse des cas de dyspepsie avec le dabigatran, l’absence d’un test de laboratoire de routine visant à mesurer de façon fiable l’effet anticoagulant et l’absence d’antidote pour renverser l’effet anticoagulant. Aucun essai randomisé contrôlé n’a effectué de comparaison directe des NACO, et le choix d’un NACO est influencé par les caract

  17. Les Elements Legers: Diffusion dans les Enveloppes Stellaires et Implications Cosmologiques

    NASA Astrophysics Data System (ADS)

    Richer, Jacques

    1992-01-01

    Les observations des abondances des elements legers (Z <= 5) sont utilisees pour estimer la quantitie de lithium qui a ete produite lors du Big -Bang, et obtenir simultanement des contraintes sur la nature des inhomogeneites qui ont pu exister durant la nucleosynthese primordiale. Nous utilisons un modele simple capable de simuler approximativement la diffusion et la retro-diffusion des neutrons a travers la matiere inhomogene durant les premieres minutes de l'expansion de l'Univers. Nous tenons compte de la difference possible entre l'abondance primordiale de Li et les abondances observees dans les plus vieilles etoiles. Cette difference (un facteur 2, environ) est estimee en construisant des modeles evolutifs d'etoiles peu massives de Population II, incluant la sedimentation gravitationnelle du lithium et de l'helium. Ces modeles montrent egalement que les ages des vieux amas stellaires sont grandement surestimes lorsqu'ils sont determines a partir de modeles stellaires n'incluant pas l'effet de la diffusion de He. Nous calculons ensuite comment evoluent les abondances de Li et Be dans des etoiles plus massives et plus jeunes, de la pre-sequence principale ou de la ZAMS, jusqu'a l'epuisement de leur hydrogene central. Les modeles incluent la sedimentation simultanee de l'helium a travers l'enveloppe. Une approche hierarchique (evolution du coeur--evolution de l'enveloppe --tri des elements traces) est utilisee pour simuler efficacement le grand nombre d'etoiles necessaire pour la construction d'isochrones. Une attention particuliere est portee aux consequences de la sedimentation de He sur l'etendue des zones convectives, et sur la diffusion de Li et Be. Les forces radiatives agissant sur ces deux elements sont calculees en detail a partir des donnees atomiques. Les etoiles simulees correspondent approximativement aux types spectraux A, F, et AmFm. Les abondances de Li et Be observees dans les etoiles jeunes de ces types sont comparees a nos predictions dans le

  18. Dan Johnson the mentor

    NASA Astrophysics Data System (ADS)

    McKinley, Richard

    2003-04-01

    I first met Dan Johnson in early 1975 as I was interviewing for an engineering job with Henning von Gierke's bioengineering and bionics laboratory at Wright-Patterson Air Force Base. From the very beginning Dan was always direct and forthright. Over the ensuing next 27 years my knowledge and respect of Dan constantly grew. This presentation will review Dan's technical and personal contributions while at the laboratory at Wright-Patterson Air Force Base. He was instrumental in the development of a national noise exposure criteria with the equal-energy-rule, an accurate single number hearing protector attenuation measure based on ``C-A,'' an impulse noise exposure criteria, a longitudinal study of hearing loss in children, development of noise dosimeters, and description of hearing damage risk from nonoccupational noise exposures such as disco's, bowling alleys, lawn mowers, and school buses. Dan has had a significant effect on my career. I and the many people who knew him at the laboratory miss him greatly.

  19. Tyrosinase processing and intracellular trafficking is disrupted in mouse primary melanocytes carrying the underwhite (uw) mutation. A model for oculocutaneous albinism (OCA) type 4.

    PubMed

    Costin, Gertrude-E; Valencia, Julio C; Vieira, Wilfred D; Lamoreux, M Lynn; Hearing, Vincent J

    2003-08-01

    Oculocutaneous albinism (OCA) type 4 is a newly identified human autosomal recessive hypopigmentary disorder that disrupts pigmentation in the skin, hair and eyes. Three other forms of OCA have been previously characterized, each resulting from the aberrant processing and/or sorting of tyrosinase, the enzyme critical to pigment production in mammals. The disruption of tyrosinase trafficking occurs at the level of the endoplasmic reticulum (ER) in OCA1 and OCA3, but at the post-Golgi level in OCA2. The gene responsible for OCA4 is the human homologue of the mouse underwhite (uw) gene, which encodes the membrane-associated transporter protein (MATP). To characterize OCA4, we investigated the processing and sorting of melanogenic proteins in primary melanocytes derived from uw/uw mice and from wild-type mice. OCA4 melanocytes were found to be constantly secreted into the medium dark vesicles that contain tyrosinase and two other melanogenic enzymes, Tyrp1 (tyrosinase-related protein 1) and Dct (DOPAchrome tautomerase); this secretory process is not seen in wild-type melanocytes. Although tyrosinase was synthesized at comparable rates in wild-type and in uw-mutant melanocytes, tyrosinase activity in uw-mutant melanocytes was only about 20% of that found in wild-type melanocytes, and was enriched only about threefold in melanosomes compared with the ninefold enrichment in wild-type melanocytes. OCA4 melanocytes showed a marked difference from wild-type melanocytes in that tyrosinase was abnormally secreted from the cells, a process similar to that seen in OCA2 melanocytes, which results from a mutation of the pink-eyed dilution (P) gene. The P protein and MATP have 12 transmembrane regions and are predicted to function as transporters. Ultrastructural analysis shows that the vesicles secreted from OCA4 melanocytes are mostly early stage melanosomes. Taken together, our results show that in OCA4 melanocytes, tyrosinase processing and intracellular trafficking to the

  20. Les neuropeptides gastro-intestinaux cibles des effets des rayonnements ionisants : altérations fonctionnelles

    NASA Astrophysics Data System (ADS)

    Linard, C.; Esposito, V.; Wysocki, J.; Griffiths, N. M.

    1998-04-01

    The symptoms associated with exposure to ionizing radiation are nausea, vomiting, diarrhoea. The response of the gut is complex involving modifications of motility and fluid and electrolyte transport. Gastrointestinal regulatory peptides have an important role in these functions. This study showed that radiation-induced tissue variations of neuropeptides have some repercussions on intestinal biological activity of these peptides soon after irradiation. In addition such modifications are also seen a few years after irradiation. Les symptômes associés à l'exposition aux rayonnements ionisants sont des nausées, vomissements et diarrhées. La réponse du système digestif est complexe, impliquant des modifications de la motilité et du transport d'eau et d'électrolytes. les neuropeptides gastro-intestinaux ont un rôle important dans ces fonctions. Cette étude montre que les variations tissulaires de ces neuropeptides induites par l'irradiation ont des répercussions sur l'activité biologique intestinale pour des temps précoces mais que ces perturbations sont encore visibles quelques années après l'irradiation.

  1. Etat des lieux des mycobactérioses atypiques au Burkina Faso: résultats d'une enquête régionale

    PubMed Central

    Zida, Sylvie; Tarnagda, Zékiba; Kaboré, Antoinette; Zingué, Dézémon; Hien, Hervé; Sanou, Adama; Michel Gomgnimbou, Kireopori; Nouctara, Moumini; Ouédraogo, Mamoudou; Ouédraogo, Oumarou; Godreuil, Sylvain; Méda, Nicolas

    2014-01-01

    Introduction L’étude avait pour but de déterminer la fréquence d'isolement des mycobactéries atypiques chez les patients déclarés tuberculeux pulmonaire à microscopie positive (TPM+) au Burkina Faso. Méthodes Il s'est agit d'une étude transversale qui s'est déroulée de mars 2011 à février 2012. Les patients TPM+ de plus de 15 ans ont été inclus dans l’étude de manière systématique dans les centres de diagnostic et de traitement (CDT) de la région sanitaire des Hauts Bassins. Une culture des mycobactéries et une identification biochimique ont été réalisées sur les échantillons des patients TPM+ La sérologie VIH a été réalisée par des tests rapides. Résultats Une fréquence de 11% (8/73) de mycobactéries atypiques et 89,0% (65/73) de mycobactéries du complexe tuberculosis ont été identifiées des 73 patients TPM+ inclus dans l’étude. La tranche d’âge de 20 à 40 ans était la plus touchée par les mycobactérioses en général et constituait 48% de l’échantillon. Nous avons trouvé 12,2% (8 / 66) de patients VIH positif, 83,3% (55 / 66) de patients VIH négatif et 4,5% (3 / 66) de patients dont le statut VIH était indéterminé. Conclusion Notre étude a mis en lumière l'implication des mycobactéries atypiques dans la pathogénie de certains patients déclarés TPM+. Le rôle des mycobactéries atypiques dans les infections pulmonaires est probablement sous estimé et devra être examiné avec plus de détails et sur un échantillon plus grand. PMID:25396014

  2. Prise en charge des traumatismes graves du rein

    PubMed Central

    Lakmichi, Mohamed Amine; Jarir, Redouane; Sadiki, Bader; Zehraoui; Bentani; Wakrim, Bader; Dahami, Zakaria; Moudouni; Sarf, Ismail

    2015-01-01

    Les traumatismes graves du rein de grade III, IV et V selon la classification de l'Amercan Society for Surgery For Trauma (ASST) sont plus rares et se retrouvent dans 5% des cas en moyenne. Leur prise en charge est souvent délicate, nécessitant alors des centres expérimentés dotés de moyen adéquats d'imagerie (scanner spiralé). Cependant, durant ces dernières années, la prise en charge de ces traumatismes a évolué vers une attitude de moins en moins chirurgicale grâce à l’évolution des techniques de la radiologie interventionnelle, de l'endourologie et des moyens de surveillance aux urgences et de réanimation. L'objectif de cette étude est d’évaluer notre expérience dans la prise en charge des traumatismes rénaux de haut grade. Notre étude rétrospective porte sur 25 cas de traumatismes grave du rein de grade III, IV et V selon la classification de l'ASST, colligés entre Janvier 2002 et Juin 2009 au service d'urologie du centre Hospitalier Universitaire Mohammed VI, Université Cadi Ayyad de Marrakech, Maroc. Nous avons étudié les données épidémiologiques, les signes cliniques et biologiques à l'admission (état de choc hémorragique, taux d'hémoglobine), les données radiologiques (échographie et scanner), les lésions associées, la prise en charge thérapeutique et les complications. L’âge moyen de nos patients était de 24,9 ans 15 et 58 ans, avec une prédominance masculine (sex-ratio = 7, 3). Le rein droit était intéressé dans 15 cas (60%). Le traumatisme rénal était fermé dans 15 cas, et ouvert par arme blanche dans 10 cas. Huit patients se sont présentés en état de choc hémorragique (32%). Une anémie inférieur à 10g /100ml a été observée dans 10 cas (40%). L'uroscanner fait systématiquement à l'admission a retrouvé un grade III (10 cas), grade IV (13 cas) et grade V (2 cas). La prise en charge a consisté en une exploration chirurgicale avec néphrectomie chez 2 cas de Grade IV pour une instabilité h

  3. Le changement comme tradition dans la recherche et la formation a la recherche en biotechnologie et en peripherie Etude de cas en sciences de la sante, sciences naturelles et genie

    NASA Astrophysics Data System (ADS)

    Bourque, Claude Julie

    Le champ de la recherche scientifique et de la formation a la recherche est traverse depuis quelques dizaines d'annees par plusieurs courants et discours associes au changement, mais peu de travaux empiriques permettent de comprendre ce qui change concretement. C'est la contribution originale de cette these au champ de l'education, plus specifiquement a l'etude sociologique de l'enseignement superieur ou sont concentrees les activites liees a la triade thematique du programme doctoral dans lequel elle a ete produite : recherche, formation et pratique. L'enquete-terrain a ete realisee en 2009 et 2010 aupres de 808 repondants affilies a 60 etablissements au Quebec et a produit un vaste materiau de nature mixte (donnees quantitatives et qualitatives). Un portrait de la nebuleuse biotechnologique qui touche les secteurs des sciences de la sante, des sciences naturelles et du genie a ete realise. Ce domaine concerne des dizaines de disciplines et se revele de nature transdisciplinaire, mais les pratiques n'y sont pas davantage marquees par le changement que celles d'autres domaines connexes. Les dynamiques sociales ont fait l'objet d'analyses comparatives dans quatre contextes: le choix des programmes, des objets et des methodes, le financement, la diffusion et la planification de la carriere. Les resultats indiquent que les echanges entre les agents traditionnellement situes au coeur des activites de recherche dominent ces dynamiques dans tous les contextes etudies. L'etude des representations au fondement des pratiques a revele l'existence de trois ecoles de pensee qui coexistent dans le champ scientifique: academique, pragmatique et economiste. Ces ecoles permettent de categoriser les agents en fonction des zones de fractures qui marquent leurs oppositions tout en identifiant ce qu'ils ont en commun. Les representations et les pratiques liees a la formation temoignent d'un habitus plutot homogene, alors que les contradictions semblent plus souvent ancrees dans des

  4. Contrôler la douleur et réduire l’usage abusif d’opioïdes

    PubMed Central

    Kotalik, Jaro

    2012-01-01

    Résumé Objectif Aider les médecins de famille à faire un juste équilibre sur le plan de l’éthique dans leurs pratiques de prescription d’opioïdes. Source des données Une recension des articles en anglais publiés entre 1985 et 2011 a été effectuée dans MEDLINE. La majorité des données probantes étaient de niveau III. Message principal Il est essentiel de suivre les guides de pratique clinique quand on prescrit des opioïdes, sauf s’il est démontré qu’une autre option est justifiée. De plus, quand on réfléchit à la pertinence de prescrire des opioïdes et aux nombreuses implications sur le plan de l’éthique, il est utile de fonder sa décision sur l’application des principes éthiques de la bienfaisance, de la non-malfaisance, du respect de l’autonomie et de la justice. En outre, il est essentiel de se tenir au fait des changements dans les lois et la règlementation, ainsi qu’à propos des registres électroniques provinciaux des ordonnances d’opioïdes. Conclusion Les médecins doivent s’assurer que la douleur de leurs patients est bien évaluée et prise en charge. Le contrôle optimal de la douleur peut exiger la prescription d’opioïdes. Cependant, l’obligation de soulager la douleur doit être exercée en juste équilibre avec l’acquittement de la responsabilité tout aussi importante de ne pas exposer les patients au risque de dépendance et de ne pas créer de possibilités de détournement de drogues, de trafic et de dépendance chez d’autres personnes. Les principes éthiques fondamentaux offrent un cadre de réflexion qui peut aider les médecins à prendre des décisions appropriées sur le plan de l’éthique au sujet de la prescription d’opioïdes.

  5. RXRα ablation in epidermal keratinocytes enhances UV radiation induced DNA damage, apoptosis, and proliferation of keratinocytes and melanocytes

    PubMed Central

    Wang, Zhixing; Coleman, Daniel J.; Bajaj, Gaurav; Liang, Xiaobo; Ganguli-Indra, Gitali; Indra, Arup Kumar

    2011-01-01

    We show here that keratinocytic nuclear receptor Retinoid X Receptor α (RXRα) regulates mouse keratinocyte and melanocyte homeostasis following acute ultraviolet radiation (UVR). Keratinocytic RXRα has a protective role on UVR-induced keratinocyte and melanocyte proliferation/differentiation, oxidative stress mediated DNA damage and cellular apoptosis. We discovered that keratinocytic RXRα in a cell autonomous manner regulate mitogenic growth responses in skin epidermis via secretion of hbEGF, GMCSF, IL1-α and COX2, and activation of MAPK pathways. We identified altered expression of several keratinocyte-derived mitogenic paracrine growth factors such as ET-1, HGF, α–MSH, SCF and FGF2 in skin of mice lacking RXRα in epidermal keratinocytes (RXRαep−/− mice), which in a non-cell autonomous manner modulated melanocyte proliferation and activation after UVR. RXRαep−/− mouse represents a unique animal model where UVR induces melanocyte proliferation/activation in both epidermis and dermis. Considered together, our results suggest that RXR antagonists, together with inhibitors of cell proliferation can be effective to prevent solar UV radiation induced photo-carcinogenesis. PMID:20944655

  6. Transplantation of melanocytes obtained from the skin ameliorates apomorphine-induced abnormal behavior in rodent hemi-parkinsonian models.

    PubMed

    Asanuma, Masato; Miyazaki, Ikuko; Diaz-Corrales, Francisco J; Higashi, Youichirou; Namba, Masayoshi; Ogawa, Norio

    2013-01-01

    Tyrosinase, which catalyzes both the hydroxylation of tyrosine and consequent oxidation of L-DOPA to form melanin in melanocytes, is also expressed in the brain, and oxidizes L-DOPA and dopamine. Replacement of dopamine synthesis by tyrosinase was reported in tyrosine hydroxylase null mice. To examine the potential benefits of autograft cell transplantation for patients with Parkinson's disease, tyrosinase-producing cells including melanocytes, were transplanted into the striatum of hemi-parkinsonian model rats or mice lesioned with 6-hydroxydopamine. Marked improvement in apomorphine-induced rotation was noted at day 40 after intrastriatal melanoma cell transplantation. Transplantation of tyrosinase cDNA-transfected hepatoma cells, which constitutively produce L-DOPA, resulted in marked amelioration of the asymmetric apomorphine-induced rotation in hemi-parkinsonian mice and the effect was present up to 2 months. Moreover, parkinsonian mice transplanted with melanocytes from the back skin of black newborn mice, but not from albino mice, showed marked improvement in the apomorphine-induced rotation behavior up to 3 months after the transplantation. Dopamine-positive signals were seen around the surviving transplants in these experiments. Taken together with previous studies showing dopamine synthesis and metabolism by tyrosinase, these results highlight therapeutic potential of intrastriatal autograft cell transplantation of melanocytes in patients with Parkinson's disease. PMID:23776585

  7. [Leukoderma caused by chemicals: mechanisms underlying 4-alkyl/aryl-substituted phenols- and rhododendrol-induced melanocyte loss].

    PubMed

    Nishimaki-Mogami, Tomoko

    2015-01-01

    Chemical leukoderma is a skin depigmentation disorder known to occur in manufactural workplace through contact with chemicals, such as monobenzyl ether of hydroquinone (MBEH) and 4-tert- butylphenol (4-TBP). In the skin depigmented -legions induced by these chemicals, the number of melanocyte was severely decreased. Anti-melanoma agent 4-cysteaminylphenol (4-SCAP) and its derivatives are also known to cause leukoderma. Evidence has accumulated supporting that typical class of chemicals causing leukoderma is "4-alkyl/aryl-substituted phenols/catechols", which are structurally similar to melanin precursor tyrosine. Tyrosinase-mediated oxidation of these chemicals yields toxic ortho-quinones which bind to cellular proteins and produce reactive oxygen species. Accordingly, this tyrosinase-dependent metabolic activation is thought to cause melanocyte-specific damage and subsequent immune reactions toward melanocytes. Recently, rhododendrol, an inhibitor of tyrosinase developed for so-called lightening/whitening cosmetics, was shown to cause leukoderma in the users. In this review, I document the causes of known chemical leukoderma and rhododendrol- induced leukoderma, focusing on their common mechanisms underlying melanocyte loss. PMID:26821466

  8. Rhododenol and raspberry ketone impair the normal proliferation of melanocytes through reactive oxygen species-dependent activation of GADD45.

    PubMed

    Kim, Minjeong; Baek, Heung Soo; Lee, Miri; Park, Hyeonji; Shin, Song Seok; Choi, Dal Woong; Lim, Kyung-Min

    2016-04-01

    Rhododenol or rhododendrol (RD, 4-(4-hydroxyphenyl)-2-butanol) occurs naturally in many plants along with raspberry ketone (RK, 4-(4-hydroxyphenyl)-2-butanone), a ketone derivative, which include Nikko maple tree (Acer nikoense) and white birch (Betula platyphylla). De-pigmenting activity of RD was discovered and it was used as a brightening ingredient for the skin whitening cosmetics. Recently, cosmetics containing RD were withdrawn from the market because a number of consumers developed leukoderma, inflammation and erythema on their face, neck and hands. Here, we explored the mechanism underlying the toxicity of RD and RK against melanocytes using B16F10 murine melanoma cells and human primary epidermal melanocytes. Treatment with RD or RK resulted in the decreased cell viability in a dose-dependent manner which appeared from cell growth arrest. Consistently, ROS generation was significantly increased by RD or RK as determined by DCF-enhanced fluorescence. An antioxidant enzyme, glutathione peroxidase was depleted as well. In line with ROS generation, oxidative damages and the arrest of normal cell proliferation, GADD genes (Growth Arrest and DNA Damage) that include GADD45 and GADD153, were significantly up-regulated. Prevention of ROS generation with an anti-oxidant, N-acetylcysteine (NAC) significantly rescued RD and RK-suppressed melanocyte proliferation. Consistently, up-regulation of GADD45 and GADD153 was significantly attenuated by NAC, suggesting that increased ROS and the resultant growth arrest of melanocytes may contribute to RD and RK-induced leukoderma. PMID:26867644

  9. Loss of Oca2 disrupts the unfolded protein response and increases resistance to endoplasmic reticulum stress in melanocytes.

    PubMed

    Cheng, Tsing; Orlow, Seth J; Manga, Prashiela

    2013-11-01

    Accumulation of proteins in the endoplasmic reticulum (ER) typically induces stress and initiates the unfolded protein response (UPR) to facilitate recovery. If homeostasis is not restored, apoptosis is induced. However, adaptation to chronic UPR activation can increase resistance to subsequent acute ER stress. We therefore investigated adaptive mechanisms in Oculocutaneous albinism type 2 (Oca2)-null melanocytes where UPR signaling is arrested despite continued tyrosinase accumulation leading to resistance to the chemical ER stressor thapsigargin. Although thapsigargin triggers UPR activation, instead of Perk-mediated phosphorylation of eIF2α, in Oca2-null melanocytes, eIF2α was rapidly dephosphorylated upon treatment. Dephosphorylation was mediated by the Gadd34-PP1α phosphatase complex. Gadd34-complex inhibition blocked eIF2α dephosphorylation and significantly increased Oca2-null melanocyte sensitivity to thapsigargin. Thus, Oca2-null melanocytes adapt to acute ER stress by disruption of pro-apoptotic Perk signaling, which promotes cell survival. This is the first study to demonstrate rapid eIF2α dephosphorylation as an adaptive mechanism to ER stress. PMID:23962237

  10. Regulation of eumelanin / pheomelanin synthesis and visible pigmentation in melanocytes by ligands of the melanocortin 1 receptor

    PubMed Central

    Le Pape, Elodie; Wakamatsu, Kazumasa; Ito, Shosuke; Wolber, Rainer; Hearing, Vincent J.

    2008-01-01

    The production of melanin in the hair and skin is tightly regulated by the melanocortin 1 receptor (MC1R) whose activation is controlled by 2 secreted ligands, α-melanocyte stimulating hormone (αMSH) and agouti signal protein (ASP). Since melanin is extremely stable, lasting years in biological tissues, the mechanism underlying the relatively rapid decrease in visible pigmentation elicited by ASP is of obvious interest. In this study, the effects of ASP and αMSH on the regulation of melanin synthesis and on visible pigmentation were assessed in normal murine melanocytes and were compared with the quick depigmenting effect of the tyrosinase inhibitor, phenylthiourea (PTU). αMSH increased pheomelanin levels prior to increasing eumelanin content over 4 days of treatment. Conversely, ASP switched off the pigment synthesis pathway, reducing eu- and pheo- melanin synthesis within 1 day of treatment that was proportional to the decrease in tyrosinase protein level and activity. These results demonstrate that the visible depigmentation of melanocytes induced by ASP does not require the degradation of existing melanin but rather is due to the dilution of existing melanin by melanocyte turnover, which emphasizes the importance of pigment distribution to visible color. PMID:18627531

  11. Retinoid-X-Receptors (α/β) in Melanocytes Modulate Innate Immune Responses and Differentially Regulate Cell Survival following UV Irradiation

    PubMed Central

    Coleman, Daniel J.; Garcia, Gloria; Hyter, Stephen; Jang, Hyo Sang; Chagani, Sharmeen; Liang, Xiaobo; Larue, Lionel; Ganguli-Indra, Gitali; Indra, Arup K.

    2014-01-01

    Understanding the molecular mechanisms of ultraviolet (UV) induced melanoma formation is becoming crucial with more reported cases each year. Expression of type II nuclear receptor Retinoid-X-Receptor α (RXRα) is lost during melanoma progression in humans. Here, we observed that in mice with melanocyte-specific ablation of RXRα and RXRβ, melanocytes attract fewer IFN-γ secreting immune cells than in wild-type mice following acute UVR exposure, via altered expression of several chemoattractive and chemorepulsive chemokines/cytokines. Reduced IFN-γ in the microenvironment alters UVR-induced apoptosis, and due to this, the survival of surrounding dermal fibroblasts is significantly decreased in mice lacking RXRα/β. Interestingly, post-UVR survival of the melanocytes themselves is enhanced in the absence of RXRα/β. Loss of RXRs α/β specifically in the melanocytes results in an endogenous shift in homeostasis of pro- and anti-apoptotic genes in these cells and enhances their survival compared to the wild type melanocytes. Therefore, RXRs modulate post-UVR survival of dermal fibroblasts in a “non-cell autonomous” manner, underscoring their role in immune surveillance, while independently mediating post-UVR melanocyte survival in a “cell autonomous” manner. Our results emphasize a novel immunomodulatory role of melanocytes in controlling survival of neighboring cell types besides controlling their own, and identifies RXRs as potential targets for therapy against UV induced melanoma. PMID:24810760

  12. Polycaprolactone fiber meshes provide a 3D environment suitable for cultivation and differentiation of melanocytes from the outer root sheath of hair follicle.

    PubMed

    Savkovic, Vuk; Flämig, Franziska; Schneider, Marie; Sülflow, Katharina; Loth, Tina; Lohrenz, Andrea; Hacker, Michael Christian; Schulz-Siegmund, Michaela; Simon, Jan-Christoph

    2016-01-01

    Melanocytes differentiated from the stem cells of human hair follicle outer root sheath (ORS) have the potential for developing non-invasive treatments for skin disorders out of a minimal sample: of hair root. With a robust procedure for melanocyte cultivation from the ORS of human hair follicle at hand, this study focused on the identification of a suitable biocompatible, biodegradable carrier as the next step toward their clinical implementation. Polycaprolactone (PCL) is a known biocompatible material used for a number of medical devices. In this study, we have populated electrospun PCL fiber meshes with normal human epidermal melanocytes (NHEM) as well as with hair-follicle-derived human melanocytes from the outer root sheath (HUMORS) and tested their functionality in vitro. PCL fiber meshes evidently provided a niche for melanocytes and supported their melanotic properties. The cells were tested for gene expression of PAX3, PMEL, TYR and MITF, as well as for proliferation, expression of melanocyte marker proteins tyrosinase and glycoprotein 100 (gp100), L-DOPA-tautomerase enzymatic activity and melanin content. Reduced mitochondrial activity and PAX-3 gene expression indicated that the three-dimensional PCL scaffold supported differentiation rather than proliferation of melanocytes. The monitored melanotic features of both the NHEM and HUMORS cultivated on PCL scaffolds significantly exceeded those of two-dimensional adherent cultures. PMID:26126647

  13. UVB-irradiated keratinocytes induce melanoma-associated ganglioside GD3 synthase gene in melanocytes via secretion of tumor necrosis factor α and interleukin 6.

    PubMed

    Miyata, Maiko; Ichihara, Masatoshi; Tajima, Orie; Sobue, Sayaka; Kambe, Mariko; Sugiura, Kazumitsu; Furukawa, Koichi; Furukawa, Keiko

    2014-03-01

    Although expression of gangliosides and their synthetic enzyme genes in malignant melanomas has been well studied, that in normal melanocytes has been scarcely analyzed. In particular, changes in expression levels of glycosyltransferase genes responsible for ganglioside synthesis during evolution of melanomas from melanocytes are very important to understand roles of gangliosides in melanomas. Here, expression of glycosyltransferase genes related to the ganglioside synthesis was analyzed using RNAs from cultured melanocytes and melanoma cell lines. Quantitative RT-PCR revealed that melanomas expressed high levels of mRNA of GD3 synthase and GM2/GD2 synthase genes and low levels of GM1/GD1b synthase genes compared with melanocytes. As a representative exogenous stimulation, effects of ultraviolet B (UVB) on the expression levels of 3 major ganglioside synthase genes in melanocytes were analyzed. Although direct UVB irradiation of melanocytes caused no marked changes, culture supernatants of UVB-irradiated keratinocytes (HaCaT cells) induced definite up-regulation of GD3 synthase and GM2/GD2 synthase genes. Detailed examination of the supernatants revealed that inflammatory cytokines such as TNFα and IL-6 enhanced GD3 synthase gene expression. These results suggest that inflammatory cytokines secreted from UVB-irradiated keratinocytes induced melanoma-associated ganglioside synthase genes, proposing roles of skin microenvironment in the promotion of melanoma-like ganglioside profiles in melanocytes. PMID:24548412

  14. Selective cytotoxicity of 4-S-cysteaminylphenol on follicular melanocytes of the black mouse: rational basis for its application to melanoma chemotherapy

    SciTech Connect

    Ito, Y.; Jimbow, K.

    1987-06-15

    We have previously shown that 4-S-cysteaminylphenol (4-S-CAP) causes a significant inhibition of in vivo melanoma growth. To clarify the mechanism of the in vivo antimelanoma effect, this study evaluated the cellular and subcellular changes of follicular melanocytes after s.c. administration of 4-S-CAP on the lumbar areas of black and albino mice. 4-S-CAP produced a prompt, selective swelling and lysis of melanocytes, resulting eventually in the necrosis of melanocytes and the depigmentation of black hair follicles. None of the degenerative changes were seen in melanocytes and keratinocytes of control albino follicles. Comparison of melanocytes in black and albino follicles revealed that melanin synthesis is highly active in the melanocytes of black follicles while melanin and tyrosinase synthesis is not seen in the melanocytes of albino follicles. The findings indicate that the selective melanocytotoxicity of 4-S-CAP is manifested by lysis and necrosis of cells which are actively engaged in melanin synthesis. 4-S-CAP appears to provide a new modality for rational chemotherapy of malignant melanoma.

  15. Differentiating intratumoral melanocytes from Langerhans cells in nonmelanocytic pigmented skin tumors in vivo by label-free third-harmonic generation microscopy

    NASA Astrophysics Data System (ADS)

    Weng, Wei-Hung; Liao, Yi-Hua; Tsai, Ming-Rung; Wei, Ming-Liang; Huang, Hsin-Yi; Sun, Chi-Kuang

    2016-07-01

    Morphology and distribution of melanocytes are critical imaging information for the diagnosis of melanocytic lesions. However, how to image intratumoral melanocytes noninvasively in pigmented skin tumors is seldom investigated. Third-harmonic generation (THG) is shown to be enhanced by melanin, whereas high accuracy has been demonstrated using THG microscopy for in vivo differential diagnosis of nonmelanocytic pigmented skin tumors. It is thus desirable to investigate if label-free THG microscopy was capable to in vivo identify intratumoral melanocytes. In this study, histopathological correlations of label-free THG images with the immunohistochemical images stained with human melanoma black (HMB)-45 and cluster of differentiation 1a (CD1a) were made. The correlation results indicated that the intratumoral THG-bright dendritic-cell-like signals were endogenously derived from melanocytes rather than Langerhans cells (LCs). The consistency between THG-bright dendritic-cell-like signals and HMB-45 melanocyte staining showed a kappa coefficient of 0.807, 84.6% sensitivity, and 95% specificity. In contrast, a kappa coefficient of -0.37, 21.7% sensitivity, and 30% specificity were noted between the THG-bright dendritic-cell-like signals and CD1a staining for LCs. Our study indicates the capability of noninvasive label-free THG microscopy to differentiate intratumoral melanocytes from LCs, which is not feasible in previous in vivo label-free clinical-imaging modalities.

  16. SCF/c-kit signaling is required in 12-O-tetradecanoylphorbol-13-acetate-induced migration and differentiation of hair follicle melanocytes for epidermal pigmentation.

    PubMed

    Qiu, Weiming; Yang, Ke; Lei, Mingxing; Yan, Hongtao; Tang, Hui; Bai, Xiufeng; Yang, Guihong; Lian, Xiaohua; Wu, Jinjin

    2015-05-01

    Hair follicle melanocyte stem cells (McSCs) are responsible for hair pigmentation and also function as a major melanocyte reservoir for epidermal pigmentation. However, the molecular mechanism promoting McSCs for epidermal pigmentation remains elusive. 12-O-tetradecanoylphorbol-13-acetate (TPA) mimics key signaling involved in melanocyte growth, migration and differentiation. We therefore investigated the molecular basis for the contribution of hair follicle McSCs to epidermal pigmentation using the TPA induction model. We found that repetitive TPA treatment of female C57BL/6 mouse dorsal skin induced epidermal pigmentation by increasing the number of epidermal melanocytes. Particularly, TPA treatment induced McSCs to initiate proliferation, exit the stem cell niche and differentiate. We also demonstrated that TPA promotes melanoblast migration and differentiation in vitro. At the molecular level, TPA treatment induced robust expression of stem cell factor (SCF) in keratinocytes and c-kit in melanoblasts and melanocytes. Administration of ACK2, a neutralizing antibody against the Kit receptor, suppressed mouse epidermal pigmentation, decreased the number of epidermal melanocytes, and inhibited melanoblast migration. Taken together, our data demonstrate that TPA promotes the expansion, migration and differentiation of hair follicle McSCs for mouse epidermal pigmentation. SCF/c-kit signaling was required for TPA-induced migration and differentiation of hair follicle melanocytes. Our findings may provide an excellent model to investigate the signaling mechanisms regulating epidermal pigmentation from mouse hair follicle McSCs, and a potential therapeutic option for skin pigmentation disorders. PMID:25727244

  17. Profil anthropometrique des enfants scolarises tananariviens

    PubMed Central

    Razafimanantsoa, Fetralinjiva; Razafindramaro, Notahiana; Raherimandimby, Hasina; Robinson, Annick; RakotoAlson, Olivat; Rasamindrakotroka, Andry

    2013-01-01

    Les enfants tananariviens sont en état de malnutrition chronique. Notre objectif est d’évaluer l'indice de masse corporelle (IMC) pour estimer les enfants apparemment "sains". Une enquête et une mesure de la taille et du poids des enfants scolarisés tananariviens de 6 à 11 ans ont été réalisées. Après leur accord, la taille et l'indice de masse corporelle des 442 enfants tirés au hasard ont été ainsi obtenus. L'analyse de la moyenne de la taille a révélé une différence significative à 8 ans, une différence non évidente sur l'indice de masse corporelle. La comparaison avec les valeurs de référence (OMS 2006) a montré un retard statural de 34% avec une tendance globale à la hausse et un déficit pondéral égal à 5,5% selon le z score. Ainsi, au sein d'une population malnutrie, l'indice de masse corporelle pourrait être utilisé comme un des paramètres à considérer dans l’évaluation de l’état de santé pour classer ces enfants en bonne santé apparente. PMID:24711862

  18. Dermatomyosite et panniculite: place des immunoglobulines

    PubMed Central

    Abdelhafidh, Nadia Ben; Toujeni, Sana; Kefi, Asma; Bousetta, Najeh; Sayhi, Sameh; Gharsallah, Imen; Othmani, Salah

    2016-01-01

    La panniculite est une maladie inflammatoire du tissu adipeux sous-cutané rarement associée à la dermatomyosite. Elle peut survenir avant, après ou en même temps que l'atteinte musculaire. Dans la plupart des cas, l’évolution de la panniculite et des autres atteintes de la dermatomyosite est favorable sous traitement corticoïde et/ou immunosuppresseur. Nous rapportons le cas d'une patiente âgée de 48 ans ayant présenté des lésions de panniculite précédant de 2 mois les signes musculaires. L'atteinte cutanée était résistante au traitement corticoïde associés aux immunosuppresseurs ce qui a nécessité le recours au traitement par Immunoglobulines polyvalentes permettant ainsi une amélioration à la fois de l'atteinte cutanée et musculaire.

  19. Dépistage des maladies cardiovasculaires chez des étudiants de l'Université de Douala et influence des activités physiques et sportives

    PubMed Central

    Ewane, Marielle Epacka; Mandengue, Samuel Honoré; Priso, Eugene Belle; Tamba, Stéphane Moumbe; Ahmadou; Fouda, André Bita

    2012-01-01

    Introduction Les maladies cardiovasculaires (MCV) constituent l'une des principales causes de mortalité dans les pays en développement. Le dépistage de ces dernières chez des jeunes est un défi dans la lutte contre leur expansion. Le but de cette étude était de dépister ces maladies au sein d'une population jeunes d’étudiants camerounais. Methodes Deux mille six cent cinquante-huit étudiants de l'Université de Douala (23,6 ± 2,9 ans, sex-ratio H/F = 0,9) ont en Avril - Mai 2011 participé à une campagne de dépistage gratuit du diabète, de l'hypertension artérielle (HTA) et de l'obésité. Ils ont également été soumis à une d'enquête évaluant leur niveau en activités physiques et sportives (APS). Resultats 12,7% des participants avaient une pression artérielle (PA) ≥ 140/90 mmHg, 3,6% étaient obèses et 0,9% avaient une glycémie ≥1,26 g/L. Des corrélations ont été trouvées entre certains facteurs de risque (diabète, hypertension et obésité) et le niveau académique d'une part (r =0,366; p < 0,0001) et le temps passé devant la télévision d'autres part (r = 0,411; p < 0,0001). L‘APS était inversement corrélée à l‘âge (r =-0,015; p < 0,0001) et au temps passé devant la télévision (r = -0,059; p = 0,002). Conclusion La présence des MCV et leurs facteurs de risque mis en évidence dans cette étude réalisée en milieu estudiantin camerounais interpelle à une prévention et une éducation dans la lutte contre ces dernières. PMID:22655111

  20. Regional Fluctuation in the Functional Consequence of LINE-1 Insertion in the Mitf Gene: The Black Spotting Phenotype Arisen from the Mitfmi-bw Mouse Lacking Melanocytes.

    PubMed

    Takeda, Kazuhisa; Hozumi, Hiroki; Ohba, Koji; Yamamoto, Hiroaki; Shibahara, Shigeki

    2016-01-01

    Microphthalmia-associated transcription factor (Mitf) is a key regulator for differentiation of melanoblasts, precursors to melanocytes. The mouse homozygous for the black-eyed white (Mitfmi-bw) allele is characterized by the white-coat color and deafness with black eyes due to the lack of melanocytes. The Mitfmi-bw allele carries LINE-1, a retrotransposable element, which results in the Mitf deficiency. Here, we have established the black spotting mouse that was spontaneously arisen from the homozygous Mitfmi-bw mouse lacking melanocytes. The black spotting mouse shows multiple black patches on the white coat, with age-related graying. Importantly, each black patch also contains hair follicles lacking melanocytes, whereas the white-coat area completely lacks melanocytes. RT-PCR analyses of the pigmented patches confirmed that the LINE-1 insertion is retained in the Mitf gene of the black spotting mouse, thereby excluding the possibility of the somatic reversion of the Mitfmi-bw allele. The immunohistochemical analysis revealed that the staining intensity for beta-catenin was noticeably lower in hair follicles lacking melanocytes of the homozygous Mitfmi-bw mouse and the black spotting mouse, compared to the control mouse. In contrast, the staining intensity for beta-catenin and cyclin D1 was higher in keratinocytes of the black spotting mouse, compared to keratinocytes of the control mouse and the Mitfmi-bw mouse. Moreover, the keratinocyte layer appears thicker in the Mitfmi-bw mouse, with the overexpression of Ki-67, a marker for cell proliferation. We also show that the presumptive black spots are formed by embryonic day 15.5. Thus, the black spotting mouse provides the unique model to explore the molecular basis for the survival and death of developing melanoblasts and melanocyte stem cells in the epidermis. These results indicate that follicular melanocytes are responsible for maintaining the epidermal homeostasis; namely, the present study has provided

  1. Regional Fluctuation in the Functional Consequence of LINE-1 Insertion in the Mitf Gene: The Black Spotting Phenotype Arisen from the Mitfmi-bw Mouse Lacking Melanocytes

    PubMed Central

    Yamamoto, Hiroaki; Shibahara, Shigeki

    2016-01-01

    Microphthalmia-associated transcription factor (Mitf) is a key regulator for differentiation of melanoblasts, precursors to melanocytes. The mouse homozygous for the black-eyed white (Mitfmi-bw) allele is characterized by the white-coat color and deafness with black eyes due to the lack of melanocytes. The Mitfmi-bw allele carries LINE-1, a retrotransposable element, which results in the Mitf deficiency. Here, we have established the black spotting mouse that was spontaneously arisen from the homozygous Mitfmi-bw mouse lacking melanocytes. The black spotting mouse shows multiple black patches on the white coat, with age-related graying. Importantly, each black patch also contains hair follicles lacking melanocytes, whereas the white-coat area completely lacks melanocytes. RT-PCR analyses of the pigmented patches confirmed that the LINE-1 insertion is retained in the Mitf gene of the black spotting mouse, thereby excluding the possibility of the somatic reversion of the Mitfmi-bw allele. The immunohistochemical analysis revealed that the staining intensity for beta-catenin was noticeably lower in hair follicles lacking melanocytes of the homozygous Mitfmi-bw mouse and the black spotting mouse, compared to the control mouse. In contrast, the staining intensity for beta-catenin and cyclin D1 was higher in keratinocytes of the black spotting mouse, compared to keratinocytes of the control mouse and the Mitfmi-bw mouse. Moreover, the keratinocyte layer appears thicker in the Mitfmi-bw mouse, with the overexpression of Ki-67, a marker for cell proliferation. We also show that the presumptive black spots are formed by embryonic day 15.5. Thus, the black spotting mouse provides the unique model to explore the molecular basis for the survival and death of developing melanoblasts and melanocyte stem cells in the epidermis. These results indicate that follicular melanocytes are responsible for maintaining the epidermal homeostasis; namely, the present study has provided

  2. Environnement des Systèmes Binaires Jeunes

    NASA Astrophysics Data System (ADS)

    Duchene, Gaspard

    2000-07-01

    La fréquence élevée des systèmes binaires, tant parmi les étoiles de la séquence principale que dans les régions de formation stellaire, a été largement mise en évidence au cours des dix dernières années. Cette constatation soulève naturellement la question de la nature du processus responsable de la formation préférentielle de ces systèmes multiples. Par ailleurs, les phénomènes d'interaction entre un compagnon et l'environnement complexe d'une étoile T Tauri sont encore trèsmal compris. C'est dans ce cadre que se place le travail conduit durant cette thèse, dont les principaux objectifs sont: i) la détermination de la fraction de binaires dans différentes populations pré-séquence principale, ii) l'étude quantitative du phénomène d'accrétion dans les systèmes binaires T Tauri, et iii) l'observation directe et la modélisation de disques circumstellaires et circumbinaires. Dans le cadre d'une recherche de binaires visuelles à l'aide du système d'optique adaptative du Télescope Canada-France-Hawaii, j'ai pris part à l'observation de plusieurs centaines d'objets situés dans différents amas stellaires jeunes. Je détaille ici l'analyse et les résultats concernant deux amas âgés de moins de deux millions d'années. Lorsqu'on considère l'ensemble des populations étudiées jusqu'à présent, on constate que la proportion de binaires visuelles parmi les étoiles de type solaire est la même dans les amas stellaires que sur la séquence principale. De plus, cette propriété ne dépend pas de l'âge de l'amas, ce qui implique que la fraction de binaires n'évolue pas après le premier million d'années dans ces amas. A l'opposé, les zones de formation peu denses, qui sont toutes très jeunes, possèdent une proportion de binaires sensiblement plus élevée. Les modèles les plus à même de reproduire ces observations sont ceux selon lesquels la fraction de binaires qui résulte de l'effondrement gravitationnel est proche de 100

  3. Bruit thermique et effets quantiques dans une cavité optique de grande finesse

    NASA Astrophysics Data System (ADS)

    Caniard, T.; Briant, T.; Heidmann, A.; Pinard, M.

    2006-10-01

    Nous nous intéressons aux bruits dans les mesures optiques de très grande sensibilité et aux limites associées. Une des limitations fondamentales des mesures interférométriques, telles que les détections d'ondes gravitationnelles, est liée aux fluctuations de la pression de radiation exercée par la lumière sur les miroirs. Celle-ci induit des corrélations quantiques entre la position des miroirs et les fluctuations de la lumière. L'observation de ces effets quantiques ouvrirait de nombreuses perspectives: étude de la limite quantique standard, production d'états comprimés, réalisation d'une mesure quantique non destructive ldots

  4. Les transfusions de globules rouges chez le nouveau-né : Des directives révisées

    PubMed Central

    2002-01-01

    En général, depuis dix ans, les professionnels de la santé qui soignent des nouveau-nés à haut risque dans des unités de soins intensifs néonatals sont plus restrictifs dans leur utilisation de transfusions de globules rouges. Le présent énoncé est conçu pour ceux qui soignent des nouveau-nés à haut risque (des prématurés aux nouveau-nés d’un mois). Il vise à fournir des directives pour réduire l’incidence d’anémie chez les nourrissons prématurés et à terme, à repérer des stratégies pour réduire le besoin de transfusions de globules rouges et à limiter l’exposition à des donneurs au sein de cette population. Des recommandations portant sur les transfusions de globules rouges sont incluses.

  5. CASH algorithm versus 3-point checklist and its modified version in evaluation of melanocytic pigmented skin lesions: The 4-point checklist.

    PubMed

    di Meo, Nicola; Stinco, Giuseppe; Bonin, Serena; Gatti, Alessandro; Trevisini, Sara; Damiani, Giovanni; Vichi, Silvia; Trevisan, Giusto

    2016-06-01

    Dermoscopy, in expert hands, increases accuracy, sensitivity and specificity in diagnosis of pigmented skin lesions of a single operator, compared with clinical examination. Simplified algorithmic methods have been developed to help less expert dermoscopists in diagnosis of melanocytic lesions. This study included 125 melanocytic skin lesions divided into melanocytic nevi, dysplastic nevi and thin melanomas (<1 mm). We compared the 3-point checklist and CASH algorithm to analyze different pigmented skin lesions. Based on preliminary results, we proposed a new modified algorithm, called the 4-point checklist, whose accuracy is similar to the CASH algorithm and whose simplicity is similar to the 3-point checklist. PMID:26589251

  6. Soins primaires des personnes victimes d’une lésion médullaire

    PubMed Central

    McColl, Mary Ann; Aiken, Alice; McColl, Alexander; Sakakibara, Brodie; Smith, Karen

    2012-01-01

    Résumé Objectif Effectuer une étude de la portée des données empiriques, entre 1980 et 2009, concernant les soins primaires aux adultes victimes d’une lésion médullaire (LME). Sources des données Une recension dans des revues révisées par des pairs de1980 à 2009 à l’aide de CINAHL, PubMed-MEDLINE, EMBASE, PsycINFO, Social Sciences Abstracts et Social Work Abstracts. Sélection des études La recherche électronique au moyen de mots-clés a permis de cerner 42 articles sur les soins primaires et les LME. Des critères d’inclusion ont servi à réduire la liste à un ensemble de 21 articles publiés en anglais qui portaient sur un échantillon de plus de 3 et présentaient une analyse empirique. Synthèse Environ 90 % des personnes atteintes d’une LME ont identifié leur médecin de famille comme étant leur docteur habituel; 63 % avaient un spécialiste des LME. Les personnes vivant à long terme avec une LME développent des rubriques complexes pour naviguer dans leurs systèmes de soins de santé personnels. Les données scientifiques ne sont pas unanimes quant à l’efficacité des programmes d’intervention directe pour le maintien de la santé et la prévention des complications à la suite d’une LME. Les données appuient cependant le suivi périodique par une équipe spécialisée et un bilan de santé annuel complet. La recherche fait valoir un fort degré d’uniformité dans l’identification des problèmes les plus courants soulevés par les personnes atteintes d’une LME en soins primaires, dont la plupart concernent l’incapacité, plus précisément les complications secondaires, comme la dysfonction intestinale ou vésicale et la douleur. Il existe aussi de bonnes données probantes à l’effet que de nombreux problèmes de santé généraux exigent de l’attention dans une telle population, comme les problèmes de la densité osseuse, la dépression et les questions entourant la santé sexuelle et la reproduction. Il y a

  7. Révision systématique des effets de la fréquence des repas en famille sur les résultats psychosociaux chez les jeunes

    PubMed Central

    Harrison, Megan E.; Norris, Mark L.; Obeid, Nicole; Fu, Maeghan; Weinstangel, Hannah; Sampson, Margaret

    2015-01-01

    Résumé Objectif Effectuer une révision systématique des effets de repas en famille fréquents sur les résultats psychosociaux chez les enfants et les adolescents et examiner s’il existe des différences dans les résultats selon le sexe. Sources des données Des études ont été cernées à la suite d’une recherche dans MEDLINE (de 1948 à la dernière semaine de juin 2011) et dans PsycINFO (de 1806 à la première semaine de juillet 2011) à l’aide de l’interface Ovide. Les expressions et mots clés MeSH utilisés seuls ou en combinaisons étaient les suivants : family, meal, food intake, nutrition, diets, body weight, adolescent attitudes, eating behaviour, feeding behaviour et eating disorders. Les bibliographies des articles jugés pertinents ont aussi été passées en revus. Sélection des études La recherche initiale a produit 1783 articles. Pour être incluses dans l’analyse, les études devaient répondre aux critères suivants : être publiées en anglais dans une revue révisée par des pairs; porter sur des enfants ou des adolescents; traiter de l’influence des repas en famille sur les paramètres psychosociaux (p. ex. consommation de drogues et autres substances, troubles de l’alimentation, dépression) chez les enfants ou les adolescents; avoir une conception d’étude appropriée, notamment des méthodes statistiques acceptables pour l’analyse des paramètres. Quatorze articles satisfaisaient aux critères d’inclusion. Deux examinateurs indépendants ont étudié et analysé les articles. Synthèse Dans l’ensemble, les résultats font valoir que la fréquence des repas en famille est inversement proportionnelle aux troubles de l’alimentation, à la consommation d’alcool et de drogues, aux comportements violents, aux sentiments de dépression ou aux pensées suicidaires chez les adolescents. Il existe une relation positive entre de fréquents repas en famille, une bonne estime de soi et la réussite scolaire. Les

  8. Dynamique particulaire dans des lits fixes et rotatifs

    NASA Astrophysics Data System (ADS)

    Dube, Olivier

    The first part of this thesis presents an evaluation of the effect, on a bed of adsorbents, of a cyclic thermal expansion and contraction of the vessels of a RFR used for gas pre-purification using the DEM. This is the first reported study of granular flow of this kind. The accuracy of the DEM-based model was assessed using experimental values of bed porosity, analytical values of predicted wall pressure based on Janssen's theory, and experimental values of wall pressure measured during the operation of a full-scale unit. In this study, the use of DEM simulations enabled the computation of a dispersion coefficient at the interface of the adsorbents. This dispersion coefficient could be used to assess the fixed bed quality after several years of use. It must be noted that the DEM-based model developed does not consider the effect of the circulating gas and the changes in particle properties likely to occur in the course of a cycle. Nevertheless, the results obtained with the proposed model show that the DEM is a valuable tool for the investigation of such slow dynamical processes, provided a careful calibration is done. The second part of this thesis presents the optimization strategy developed to determine an optimal set of scintillation detector positions and orientations. This strategy uses a mesh adaptive direct search (MADS) optimization algorithm and the detectors resolution as an objective function. The results of this work showed that the optimal positioning found by the optimization strategy is sensitive to both the objectives of the study and the experimental conditions. It can therefore be easily applied to studies different from the one conducted in this thesis. Finally, the third part of this thesis presents the characterization of the dynamics of non-spherical particles in a rotating drum. The data collected and the observations made in the laboratory showed that non-spherical particles tend to flow with a preferred spatial orientation. This preferred spatial orientation can be one of the reasons that could explain the differences observed between the flow of spherical and non-spherical particles. Mixing and segregation of bi-disperse mixtures of mono-shaped tablets and bi-disperse mixtures of bi-shaped tablets were also investigated. A traditional core segregation pattern, where the smaller/denser particles are found in the center of the bed while the larger/lighter particles are found on the outside, was observed in most cases. However, a reverse core segregation pattern was observed when long and large particles were mixed with small compact particles. In this case, the smaller/denser particles were found on the outside of the bed instead of in the center. The results obtained with this investigation are of interest in that they highlight for the first time the effect that the shape of a particle may have on flow dynamics as well as on mixing and segregation inside a rotating drum. (Abstract shortened by UMI.)

  9. Etude numerique des mecanismes d'autodiffusion dans les semiconducteurs

    NASA Astrophysics Data System (ADS)

    El-Mellouhi, Fedwa

    The most promising and most natural physical process for the formation of elementary structures in nanotechnology such as quantum dots and nanocrystals remains self-assembly. Self-assembly is governed by the atomic diffusion which is the fundamental process of mass transport due to defects (vacancies, interstitials, impurities, etc.). This work exploits recent developments in ab-initio methods based on density functional theory in order to give a reliable description of the electronic structure and migration mechanisms of vacancy type defects in semiconductors. Four main achievements in this direction are covered by this thesis. First, frequent and rare events connected to the neutral Si vacancy in silicon are identified. The calculated migration barrier to the first neighbor agrees with the experimental results obtained by Watkins et al. [1]. Second, a detailed study focuses on the stability and the charge state of As and Ga vacancies in the binary semiconducting compound GaAs with respect to experimental preparation conditions (doping, stoichiometry). Next, activated events associated to Ga vacancies are studied together with the effect of charge states on the path and the migration barrier. Gallium vacancy can migrate by jumps to the second, first and fourth neighbors with an increasing barrier for more negatively charged vacancies. In addition, a new mechanism for migration to the second neighbor have been found for negatively charged vacancies. Finally, the debate about the stability of charged Ga vacancies in GaAs at elevated temperature is analyzed. Gibbs free energy of formation is calculated by adding entropic effects. The thermal dependence of the Fermi level and of the ionization levels lead to a reversal of the preferred charge state as the temperature increases. This single set of calculated energies is suitable to fit at the same time experimental concentration profiles from positron annihilation experiments and diffusion profiles obtained from heterostructure interdiffusion experiments. Keywords. Nanostructure, Self-diffusion, Semiconductors, Defects, First principles calculation, Vacancy, ab-initio, Simulation, GaAs, Si.

  10. Spectroscopie Raman et Rayleigh stimulée des mélasses optiques unidimensionnelles (partie II)

    NASA Astrophysics Data System (ADS)

    Courtois, Jean-Yves

    Dans la première partie de cet article, nous nous sommes attachés à décrire dans le détail les caractéristiques générales des processus de diffusion Raman et Rayleigh stimulée se produisant dans les milieux atomiques et moléculaires traditionnels, de manière à bien faire ressortir les spécificités des propriétés optiques non linéaires des mélasses optiques, dont l'étude fait l'objet de cette seconde partie. L'origine de ces spécificités réside dans une particularité des atomes refroidis par laser, à savoir l'intime corrélation entre degrés de liberté internes et externes dans leur réponse non linéaire. Cette caractéristique est en fait inhérente au processus de ralentissement : d'une part la force exercée par les faisceaux lasers sur les atomes (pression de radiation et redistribution de photons) dépend fortement de l'état atomique interne, et d'autre part cet état est modifié de façon très sélective en position ou en vitesse par les ondes lasers de refroidissement (déplacements lumineux et pompage optique). Elle sous-tend toute la richesse et l'originalité du comportement non linéaire des mélasses optiques, mais aussi toute la complexité de leur modélisation théorique, qui requiert une description globale de l'évolution des degrés de liberté internes et externes des atomes sous l'action des champs lasers. Afin de mettre en évidence le lien entre ces corrélations et les propriétés non linéaires des atomes froids, nous concentrerons notre étude d'une part sur les mélasses linbot lin qui constituent un cas de couplage entre état interne et position des atomes localisés au fond des puits du potentiel associé aux déplacements lumineux (paragr. 4), et d'autre part sur les mélasses σ^+-σ- qui correspondent quant à elles à un couplage entre état interne et vitesse atomiques (paragr. 5).

  11. FBH1 protects melanocytes from transformation and is deregulated in melanomas.

    PubMed

    Jeong, Yeon-Tae; Cermak, Lukas; Guijarro, Maria V; Hernando, Eva; Pagano, Michele

    2013-04-01

    FBH1 is a member of the UvrD family of DNA helicases and plays a crucial role in the response to DNA replication stress. In particular, upon DNA replication stress, FBH1 promotes double-strand breakage and activation of the DNA-PK and ATM signaling cascades in a helicase-dependent manner. In the present manuscript, we show that FBH1 is often deleted or mutated in melanoma cells, which results in their increased survival in response to replicative stress. Accordingly, FBH1 depletion promotes UV-mediated transformation of human melanocytes. Thus, FBH1 inactivation appears to contribute to oncogenic transformation by allowing survival of cells undergoing replicative stress due to external factors such as UV irradiation. PMID:23466708

  12. A versatile method for the removal of melanin from ribonucleic acids in melanocytic cells.

    PubMed

    Satyamoorthy, K; Li, G; Van Belle, P A; Elder, D E; Herlyn, M

    2002-10-01

    Melanin pigments often co-purify during preparation of nucleic acids from cells or tissues of melanocytic origin. Contaminating melanin can severely impede subsequent analyses of RNA. We attempted to eliminate melanin in RNA preparations using selected gel matrices. We show here that co-purified melanin pigments can be largely eliminated from RNA samples after passing through polyacrylamide-based beads (Bio-Gel P-60). After isolation from the pigment-containing cells or tissues, RNA was subsequently processed through batch or column purification under acidic pH conditions. The resulting RNA was devoid of contaminating melanin pigments and amenable to molecular reactions such as polymerase chain reaction and cDNA synthesis by reverse transcriptase. Although the process results in some loss of input RNA, this purification procedure is simple, robust and can easily be adopted in any laboratory for the molecular analysis of RNA that requires removal of melanin contamination. PMID:12394186

  13. Bilateral Diffuse Uveal Melanocytic Proliferation: Molecular Genetic Analysis of a Case and Review of the Literature

    PubMed Central

    Mittal, Ruchi; Cherepanoff, Svetlana; Thornton, Sophie; Kalirai, Helen; Damato, Bertil; Coupland, Sarah E.

    2015-01-01

    Purpose of the Study To describe the clinicopathological features, mutational and chromosomal copy number analysis, and 8-year follow-up of a case of bilateral diffuse uveal melanocytic proliferation (BDUMP) associated with clear-cell carcinoma of the endometrium. Methods Histological evaluation, multiplex ligation-dependent probe amplification (MLPA) analysis and GNAQ/11 mutational analysis were performed in a 67-year-old female patient with the diagnosis of BDUMP. Results Histological evaluation revealed proliferation of bland spindle cells, diffusely replacing the uveal tract, which showed a proliferation index of less than 1%. There was absence of mutations involving the codon 209 and 183 of GNAQ, and of GNA11. MLPA analysis showed disomy 3 with polysomy 8q for both eyes. The patient died 8 years later of an unrelated condition. Conclusions Although BDUMP is considered to be a benign proliferative disease, copy number alterations of unknown significance may occur in these lesions. PMID:27171825

  14. Anti-melanogenic effects of black, green, and white tea extracts on immortalized melanocytes

    PubMed Central

    Choi, So Young; Park, Eun Ye

    2015-01-01

    Tea contains polyphenols and is one of the most popular beverages consumed worldwide. Because most tyrosinase inhibitors that regulate melanogenesis are phenol/catechol derivatives, this study investigated the inhibitory effects of Camellia sinensis water extracts (CSWEs), including black tea, green tea, and white tea extracts, on melanogenesis using immortalized melanocytes. CSWEs inhibited melanin accumulation and melanin synthesis along with tyrosinase activity in a concentration-dependent manner. These inhibitory effects were superior to those of arbutin, a well-known depigmenting agent. The anti-melanogenic activity of black (fermented) tea was higher than that of a predominant tea catecholamine, epigallocatechin gallate. CSWEs, especially black tea extract, decreased tyrosinase protein levels in a concentration-dependent manner. These results suggest that the anti-melanogenic effect of CSWEs is mediated by a decrease in both tyrosinase activity and protein expression, and may be augmented by fermentation. Thus, CSWEs could be useful skin-whitening agents in the cosmetic industry. PMID:25643794

  15. Alpha-Melanocyte Stimulating Hormone: An Emerging Anti-Inflammatory Antimicrobial Peptide

    PubMed Central

    Singh, Madhuri; Mukhopadhyay, Kasturi

    2014-01-01

    The alpha-melanocyte stimulating hormone (α-MSH) is a neuropeptide belonging to the melanocortin family. It is well known for its anti-inflammatory and antipyretic effects and shares several characteristics with antimicrobial peptides (AMPs). There have been some recent reports about the direct antimicrobial activity of α-MSH against various microbes belonging to both fungal and bacterial pathogens. Similar to α-MSH's anti-inflammatory properties, its C-terminal residues also exhibit antimicrobial activity parallel to that of the entire peptide. This review is focused on the current findings regarding the direct antimicrobial potential and immunomodulatory mechanism of α-MSH and its C-terminal fragments, with particular emphasis on the prospects of α-MSH based peptides as a strong anti-infective agent. PMID:25140322

  16. Alpha-melanocyte-stimulating hormone is a peripheral, integrative regulator of glucose and fat metabolism.

    PubMed

    Brennan, Miles B; Costa, Jessica Lynn; Forbes, Stacy; Reed, Peggy; Bui, Stephanie; Hochgeschwender, Ute

    2003-06-01

    Melanocortins are known to affect feeding and probably insulin activity through the central nervous system. It was also recently shown that peripheral alpha-melanocyte-stimulating hormone (alpha-MSH) administration can reduce weight gain in both genetic and diet-induced obese mice. As obesity is often associated with disregulation of glucose and insulin, we investigated the nature of glucose homeostasis in the obese pro-opiomelanocortin (POMC) knockout mouse. Here we report that though they are obese, mice deficient in POMC (and, thereby, deficient in alpha-MSH) are euglycemic throughout their lives. While these mice are euinsulinemic, they are hypersensitive to exogenous insulin. This defect can be reversed through administration of alpha-MSH. We demonstrate that the actions of alpha-MSH in the periphery, known from our work to include lipid metabolism effects, are also involved in glucose homeostasis. These findings substantiate a pivotal role of the POMC gene products in integrating metabolism. PMID:12851327

  17. FBH1 protects melanocytes from transformation and is deregulated in melanomas

    PubMed Central

    Jeong, Yeon-Tae; Cermak, Lukas; Guijarro, Maria V.; Hernando, Eva; Pagano, Michele

    2013-01-01

    FBH1 is a member of the UvrD family of DNA helicases and plays a crucial role in the response to DNA replication stress. In particular, upon DNA replication stress, FBH1 promotes double-strand breakage and activation of the DNA-PK and ATM signaling cascades in a helicase-dependent manner. In the present manuscript, we show that FBH1 is often deleted or mutated in melanoma cells, which results in their increased survival in response to replicative stress. Accordingly, FBH1 depletion promotes UV-mediated transformation of human melanocytes. Thus, FBH1 inactivation appears to contribute to oncogenic transformation by allowing survival of cells undergoing replicative stress due to external factors such as UV irradiation. PMID:23466708

  18. Anti-melanogenic effects of black, green, and white tea extracts on immortalized melanocytes.

    PubMed

    Kim, Young Chul; Choi, So Young; Park, Eun Ye

    2015-01-01

    Tea contains polyphenols and is one of the most popular beverages consumed worldwide. Because most tyrosinase inhibitors that regulate melanogenesis are phenol/catechol derivatives, this study investigated the inhibitory effects of Camellia sinensis water extracts (CSWEs), including black tea, green tea, and white tea extracts, on melanogenesis using immortalized melanocytes. CSWEs inhibited melanin accumulation and melanin synthesis along with tyrosinase activity in a concentration-dependent manner. These inhibitory effects were superior to those of arbutin, a well-known depigmenting agent. The anti-melanogenic activity of black (fermented) tea was higher than that of a predominant tea catecholamine, epigallocatechin gallate. CSWEs, especially black tea extract, decreased tyrosinase protein levels in a concentration-dependent manner. These results suggest that the anti-melanogenic effect of CSWEs is mediated by a decrease in both tyrosinase activity and protein expression, and may be augmented by fermentation. Thus, CSWEs could be useful skin-whitening agents in the cosmetic industry. PMID:25643794

  19. Profiles of alpha-melanocyte-stimulating hormone in the Japanese flounder as revealed by a newly developed time-resolved fluoroimmunoassay and immunohistochemistry.

    PubMed

    Amiya, Noriko; Amano, Masafumi; Takahashi, Akiyoshi; Yamanome, Takeshi; Yamamori, Kunio

    2007-03-01

    Profiles of alpha-melanocyte-stimulating hormone (alpha-MSH) in the Japanese flounder were examined by a newly developed time-resolved fluoroimmunoassay (TR-FIA) and immunohistochemistry. A TR-FIA for alpha-MSH was newly developed, and its levels in the pituitary gland and plasma of Japanese flounder reared in a white or black tank for 5 months were compared. A competitive assay using two antibodies was performed among secondary antibodies in the solid phase, alpha-MSH antibodies, samples, and europium-labeled Des-Ac-alpha-MSH. The sensitivity of the assay, defined as twice the standard deviation at a zero dose, was 0.98 ng/ml (49 pg/well). The intra- and interassay coefficients of variation of the assay were 8.8% (n=8) and 17.3% (n=5), respectively, at about 50% binding. Cross-reactivities of Des-Ac-alpha-MSH and Di-Ac-alpha-MSH were about 100%. Cross-reactivities of adrenocorticotropic hormone, salmon gonadotropin-releasing hormone (sGnRH), and chicken GnRH-II were less than 0.2%, and that of melanin-concentrating hormone was less than 2.0% at 50% binding. Displacement curves of serially twofold-diluted hypothalamus extract, pituitary gland extract, and plasma extract of Japanese flounder with the assay buffer were parallel to the alpha-MSH standard curve. Moreover, displacement curves of serially twofold-diluted hypothalamus and/or pituitary gland extract of masu salmon, goldfish, red seabream, Japanese eel, tiger puffer, and barfin flounder with the assay buffer were also parallel to the alpha-MSH standard. In Japanese flounder, total immunoreactive (ir)-alpha-MSH levels in the pituitary gland were lower in the black tank, whereas those in the plasma tended to be higher in the black tank, suggesting that the synthesis and release of alpha-MSH are higher in the black tank. alpha-MSH-ir cells were detected in the pars intermedia and a small part of the pars distalis of the pituitary gland. alpha-MSH-ir cell bodies were located in the basal hypothalamus and alpha

  20. Clinicopathological and prognostic relevance of Rap1-GAP expression in melanocytic tumors.

    PubMed

    Weiss, J; Biwer, B; Schliz, M; Jung, E G

    1997-09-01

    Rap1-GAP protein has been identified as an inactivator of Rap1 activity, a putative endogenous antagonist of Ras proteins. The Rap1-GA1 locus maps to 1p36.1-35, the region which may harbor a gene for familial melanoma. In the present immunohistochemical study we analyzed the clinicopathological and prognostic relevance of Rap1-GAP expression in 60 benign and 103 malignant melanocytic tumors. Cytoplasmic immunoreactivity was detected in the cells of 27/60 nevi (45%) and 59/103 melanomas (57%). In the latter group the frequency of Rap1-GAP expression increased (P < 0.05) with the thickness of primary tumors and was highest in metastatic lesions. Rap1-GAP protein was detected in 15/19 subsequently recurring primary melanomas (79%) but only in 32/67 tumors (47%) of patients who remained free of disease (P < 0.05) for at least 6 years. Five out of six recurring thin melanomas (< 2 mm) were found to be immunoreactive. Although being no indicator for malignant transformation of melanocytic lesions, Rap1-GAP overexpression may represent a useful marker for identifying thin high-risk melanomas. Cytoplasmic expression of Rap1-GAP has also been observed in the cells of skin appendages and in keratinocytes, particularly in suprabasal layers of the epidermis. Therefore, Rap1-GAP is likely to be associated with cellular growth and/or differentiation. However, the present study did not provide evidence that this gene, despite its chromosomal localization, represents an early melanoma gene. PMID:9373716

  1. Hair follicle melanocyte precursors are awoken by ultraviolet radiation via a cell extrinsic mechanism.

    PubMed

    Ferguson, Blake; Kunisada, Takahiro; Aoki, Hitomi; Handoko, Herlina Y; Walker, Graeme J

    2015-06-01

    Melanocyte stem cells (MCSCs) in the upper portion of the hair follicle periodically supply melanocytes (MCs) that migrate downward into the hair bulb during anagen, the growth phase of the hair cycle. However MCs can also migrate upwards. We previously observed an increase in epidermal MC density in the mouse epidermis after a single ultraviolet radiation (UVR) exposure in neonatal, but not adult mice. To better understand MCSC activation by UVR we methodically studied the response of MCs to narrow band UVB (since UVA does not invoke this response) exposure in neonatal mice, and in adults at different stages of the hair cycle. We found that a single exposure of adult mice did not induce activation of MCSCs, in any stage of the hair cycle. When adult mice MCSCs were isolated in telogen, multiple UVB exposures resulted in their activation and production of daughter cells, which migrated upwards to the epidermis. Importantly, the MCSCs produced new progeny without themselves having incurred DNA damage after UVB exposure. This, together with examination of MC localisation in the skin of mice overexpressing stem cell factor in their keratinocytes, leads us to conclude that MCSC activation by UVB is driven via paracrine production of either SCF and/or other keratinocyte cytokines. We re-examined the increase in epidermal MC density in neonatal mouse skin. This effect was much more profound after only a single exposure than that of even multiple exposures to adult skin, and we show that in this setting also, the epidermal MCs mostly derive from activation of MC precursors in the upper hair follicle, and most likely via a cell extrinsic mechanism. Hence, although adaptive changes in the skin induced by repetitive UVB exposures are necessary in adult mice, in both the adult and neonatal context the division and migration upwards of follicular MCSCs is the major mode by which epidermal MC numbers increase after UVR exposure. PMID:25966309

  2. Traitement des fractures des plateaux externes par vissage percutané assisté par arthroscopie

    PubMed Central

    Abouchane, Merouane; Belmoubarik, Amine; Benameur, Hamza; Haddoun, Ahmed Reda; Nechad, Mohammed

    2015-01-01

    Le but de notre étude est d'évaluer les résultats de fractures des plateaux tibiaux externes traitées par ostéosynthèse percutanée assistée par arthroscopie. Dix patients (8 hommes et 2 femmes) de 32 ans en moyenne ont subi cette intervention afin de réparer des fractures des plateaux tibiaux Schatzker I-III. Après avoir appliqué un garrot pneumatique, nous avons réduit et fixé la fracture au moyen de vis cannelées souschondrales. Lésions associées retrouvent deux lésions partielles du ménisque externe ont été retrouvé, traitées par résection partielle. Une orthèse de genou été de mise à but antalgique et protectrice pendant six semaines avec béquillage et interdiction de l'appui pour une durée de douze semaines avec reprise d'appui partiel au delà. La durée d'hospitalisation été d'une moyenne de cinq jours. La rééducation passive a été commence le lendemain de l'intervention et continuait dans chez un kinésithérapeute à la sortie du patient du service. Le suivi été à J7, J15, 1mois, 3mois, 6 mois puis tous les 6 mois. Neuf de nos patients ont été revu régulièrement sauf un perdu de vue. Le recul moyen de notre série été de 16 mois (10 et 24 mois). Le score de Lysholm a été utilisé pour évaluer les résultats cliniques chez nos neuf patients: excellent chez trois patients bons chez trois moyen chez un seul et mauvais chez deux patients. Tous nos neuf patients ont consolidé (figure 10 contrôle scopique d un article). Aucune gonarthrose n'a été note chez nos neuf patients due essentiellement au recul moyen faible de 16 mois. Le traitement des fractures des plateaux tibiaux externes assisté par arthroscopie produit des résultats satisfaisants et peut être accepté comme solution de rechange efficace au traitement des fractures des plateaux tibiaux causées par un choc de faible énergie. PMID:26587137

  3. Photons uniques indiscernables à partir d'une boîte quantique unique dans un cristal photonique

    NASA Astrophysics Data System (ADS)

    Laurent, S.; Varoutsis, S.; Le Gratiet, L.; Lemaître, A.; Sagnes, I.; Raineri, F.; Levenson, A.; Robert-Philip, I.; Abram, I.

    2006-10-01

    Nous avons développé et caractérisé une source de photons uniques basée sur l'émission spontanée d'une boîte quantique unique insérée dans une cavité à bande interdite photonique bidimensionnelle. Ce système nous a d'abord permis de produire des photons uniques, puis des photons uniques indiscernables avec une indiscernabilité supérieure à 70%. L'observation de l'indiscernabilité des photons, impossible sans un raccourcissement important de la durée de vie, met en évidence un effet Purcell supérieur à 25 dans ce système.

  4. Regles de fusion en theorie des champs conformes

    NASA Astrophysics Data System (ADS)

    Begin, Luc

    1999-10-01

    Les théories de champs conformes constituent un domaine de recherche très actif avec de nombreuses applications en physique statistique, en matière condensée, en théorie des cordes, en mathématiques, etc. Nous analysons ici le calcul des règles de fusion dans les modèles Wess- Zumino-Witten par des méthodes positives. Les règles de fusion sont des quantités importantes puisqu'elles indiquent comment se combinent les champs primaires de la théorie. L'approche présentée est basée sur l'hypothèse que les règles de fusion sont décrites par un système d'inéquations linéaire et homogène et mène au concept original de «base de fusion». Cette approche simple et générale permet d'utiliser les méthodes combinatoires et de programmation linéaire pour construire les fonctions génératrices et les bases de fusion. Cette méthode permet d'obtenir des résultats originaux et explicites pour les algèbres su (3), su (4) et sp (4).

  5. Medium-sized congenital melanocytic nevus of the forehead, glabella and temple – surgical treatment and long-term follow-up.

    PubMed

    Goldman, A; Wollina, U; Tchernev, G; Chokoeva, A A; Lotti, T

    2016-01-01

    Congenital melanocytic nevi can be stigmatising for the patient. Larger nevi bear an increased risk for melanoma development. Large congenital melanocytic nevi may be a symptom of neurocutaneous melanosis. We report on a 5-year-old boy with an extensive hair-bearing facial congenital melanocytic nevus, covering forehead, glabella and temple region associated with unilateral brow and blepharoptosis. The lesion was excised en bloc. The resulting defect had been closed by full thickness skin graft. Healing was unremarkable and long-term follow-up over 13 years demonstrated a satisfying esthetic and functional outcome. There was no evidence of melanoma development. Surgery is an option for disfiguring larger congenital melanocytic nevi as long as esthetics and function can be preserved. Long-term follow-up is recommended due to the increased risk of melanoma. PMID:27373136

  6. Regulation of type I-interferon responses in the human epidermal melanocyte cell line SKMEL infected by the Ross River alphavirus.

    PubMed

    Assi, Mohamad; Thon-Hon, Vincent Gérard; Jaffar-Bandjee, Marie-Christine; Martinez, Audrey; Gasque, Philippe

    2015-12-01

    Melanocytes are melanin-producing cells and with emerging innate immune functions including the expression of antiviral interferon-type I cytokines. We herein ascertained the susceptibility of the human melanocytes to Ross River alphavirus (RRV) infection and analyzed the subsequent immune responses. We demonstrated for the first time that (1) SKMEL-28 melanocyte cell line was susceptible to RRV infection and displaying major cytopathic activities and (2) RRV interfered with the interferon-type I response by altering nuclear translocation of pSTAT1 and pSTAT2 in infected SKMEL-28. These results suggest that the human melanoma cell line SKMEL-28 is a valuable model to analyze the mechanisms involved in severe skin manifestations and melanocyte's immunity at the portal of entry of major infection by arboviruses. PMID:26159111

  7. Visualization of Melanosome Dynamics within Wild-Type and Dilute Melanocytes Suggests a Paradigm for Myosin V Function In Vivo

    PubMed Central

    Wu, Xufeng; Bowers, Blair; Rao, Kang; Wei, Qin; Hammer, John A.

    1998-01-01

    Unlike wild-type mouse melanocytes, where melanosomes are concentrated in dendrites and dendritic tips, melanosomes in dilute (myosin Va−) melanocytes are concentrated in the cell center. Here we sought to define the role that myosin Va plays in melanosome transport and distribution. Actin filaments that comprise a cortical shell running the length of the dendrite were found to exhibit a random orientation, suggesting that myosin Va could drive the outward spreading of melanosomes by catalyzing random walks. In contrast to this mechanism, time lapse video microscopy revealed that melanosomes undergo rapid (∼1.5 μm/s) microtubule-dependent movements to the periphery and back again. This bidirectional traffic occurs in both wild-type and dilute melanocytes, but it is more obvious in dilute melanocytes because the only melanosomes in their periphery are those undergoing this movement. While providing an efficient means to transport melanosomes to the periphery, this component does not by itself result in their net accumulation there. These observations, together with previous studies showing extensive colocalization of myosin Va and melanosomes in the actin-rich periphery, suggest a mechanism in which a myosin Va–dependent interaction of melanosomes with F-actin in the periphery prevents these organelles from returning on microtubules to the cell center, causing their distal accumulation. This “capture” model is supported by the demonstration that (a) expression of the myosin Va tail domain within wild-type cells creates a dilute-like phenotype via a process involving initial colocalization of tail domains with melanosomes in the periphery, followed by an ∼120-min, microtubule-based redistribution of melanosomes to the cell center; (b) microtubule-dependent melanosome movement appears to be damped by myosin Va; (c) intermittent, microtubule-independent, ∼0.14 μm/s melanosome movements are seen only in wild-type melanocytes; and (d) these movements do

  8. Lambeaux autofermants pour le traitement des brulures electriques du scalp par haut voltage

    PubMed Central

    Hafidi, J.; El Mazouz, S.; El Mejatti, H.; Fejjal, N.; Gharib, N.E.; Abbassi, A.; Belmahi, A.M.

    2011-01-01

    Summary Les brûlures électriques par haut voltage sont responsables de gros dégâts tissulaires en immédiat et dans les jours suivant l’accident du fait de la chaleur importante dégagée par effet joule et de la thrombose microvasculaire évolutive. Les pertes de substances du scalp secondaires à ces brûlures nécessitent une couverture par lambeaux vu la destruction du périoste et du calvarium en regard. De juin 1997 à juin 2008, 15 patients ont été traités pour des pertes de substance du scalp secondaires à des brûlures électriques par haut voltage de diamètre allant de 8 à 11 cm et siégeant dans la région tonsurale. Ces patients ont été opérés dans la première semaine suivant l’accident. Les pertes de substance du scalp de taille moyenne secondaires à ces brûlures peuvent être couvertes per primam de façon fiable par des lambeaux locaux axialisés et multiples. Nous relatons l’expérience du Service de Chirurgie Plastique du Centre Hospitalier Universitaire Ibn-Sina, Rabat, Maroc, dans la gestion et la prise en charge de ces brûlures. PMID:22262963