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1
Ye, Hui. "Arsenic poisoning of nickel catalysts". HKBU Institutional Repository, 1992. http://repository.hkbu.edu.hk/etd_ra/19.
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Drysdale, Mallory Elizabeth Brennan. "Application of simulated lung fluid analysis to characterize the influence of smelter activity on the respiratory bioaccessibility of nickel-bearing soils in Kalgoorlie, Western Australia". Thesis, Kingston, Ont. : [s.n.], 2008. http://hdl.handle.net/1974/1300.
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Caldas, L. Q. A. "An investigation of the immunotoxicology of chromium, nickel and barium from inhaled metal fumes". Thesis, University of Bradford, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374914.
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Muteba, Itone. "Research on nickel alloy sensitivity". Title page, Contents and Abstract only, 1999. http://web4.library.adelaide.edu.au/theses/09DM/09dmm992.pdf.
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"April 1999." Includes bibliographical references (leaves 46-51). Aims to collect information about the numbers of dental workers who are sensitive or allergic to nickel and to help identify signs which might predict those people who are most likely to be sensitive to nickel. Uses a standard patch test to identify sensitive subjects.
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Rahayu, Ucu. "The influence of dissolved organic carbon (DOC) and calcium on the toxicity of copper and nickel to the freshwater alga Selenastrum capricornutum and the zooplankter Daphnia magna". Thesis, University of Ottawa (Canada), 2000. http://hdl.handle.net/10393/9241.
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The toxicity of copper and nickel was measured in algal cultures of Selenastrum capricornutum and zooplankton cultures of Daphnia magna to determine if dissolved organic carbon (DOC) and/or calcium concentrations can influence toxicity of these two metals. Water samples were collected from the Raisin River (high DOC and high calcium), the St. Lawrence River (low DOC and high calcium), the Ottawa River (medium DOC and calcium) as well as two lakes in Nova Scotia. The concentration sufficient to kill half the population of Daphnia magna after 48h of exposure (LC50), and the inhibition of cell growth of S. capricornutum after 72 h of exposure (IC50) were used to determine the sensitivity of these species to copper or nickel toxicity in these 5 water samples. In Part 3, I showed that the protection against copper or nickel toxicity was reduced with UVB radiation even though the total DOC was reduced by only 18%. The role of EDTA in the toxicity of copper and nickel on S. capricornutum was investigated in part 4. (Abstract shortened by UMI.)
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Ptashynski, Melanie D. "Accumulation, distribution, and toxicology of nickel in lake whitefish, Coregonus clupeaformis, and lake trout, Salvelinus namaycush, exposed through the dietary route of uptake". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ53209.pdf.
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Custer, Kevin Wayne. "FACTORS CONTROLLING NICKEL BIOAVAILABILITY AND EFFECTS ON BENTHIC INVERTEBRATES IN HARDWATER FRESHWATER STREAMS". Wright State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=wright1364295154.
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Cloran, Christina Elizabeth. "Investigating Nickel Flux and Toxicity in Clay Sediments with Batch and Stream Recirculating Flume Experiments". Wright State University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=wright1229973400.
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Le, Ngoc Michel. "Les effets allergiques et toxiques du nickel". Paris 5, 1997. http://www.theses.fr/1997PA05P094.
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Aubry, Alain. "Etat, devenir et toxicité du nickel en hydrologie". Paris 5, 1994. http://www.theses.fr/1994PA05P250.
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NIESSEN, Sylvie. "Contribution à l'étude de la récupération d'ions nickel (II) en solution par couplage complexation-ultrafiltration-électrolyse". Montpellier 2, 1993. http://www.theses.fr/1993MON20074.
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De nombreux effluents industriels contiennent des metaux en solution qui presentent une certaine toxicite et qu'il faut eliminer avant rejet. Dans ce travail, nous etudions la possibilite d'eliminer le nickel present dans un effluent par complexation avec un macroligand de qualite industrielle (acide polyacrylique sulfone), puis ultrafiltration. Le concentrat est ensuite electrolyse afin de recuperer le metal sous forme solide. Une premiere partie presente les essais filtration du complexe. Les resultats montrent que l'on peut retenir le nickel a 99% dans certaines conditions. Ont ete etudies le role du ph, celui de la presence d'un autre complexant comme l'ammoniaque et celui de la presence de sels. L'ensemble des observations est interprete d'apres la connaissance de la nature des especes presentes en solution dans les differentes conditions experimentales. On note que la presence de sels influence fortement les performances de l'ultrafiltration. La seconde partie concerne l'electrolyse du nickel complexe. Une etude polarographique prealable permet de montrer le caractere labile du complexe nickel-polymere et les modifications apportees par variation de ph, addition d'ammoniaque ou de sels confirment l'interpretation donnee pour les resultats de filtration. L'electrodeposition du nickel par electrolyse du concentrat est enfin abordee et l'influence des conditions d'electrolyse est etudiee. Cependant, l'interet du procede tel qu'il est decrit dans ce travail est limite par une perte en polymere lors de l'ultrafiltration et une degradation partielle au cours de l'electrolyse
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L'Huillier, Laurent. "Biodisponibilité du nickel dans les sols ferrallitiques ferritiques de Nouvelle-Calédonie : effets toxiques de Ni sur le développement et la physiologie du maïs". Montpellier 2, 1994. http://www.theses.fr/1994MON20292.
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La mobilite et la biodisponibilite du nickel ont ete caracterisees dans les sols ferrallitiques ferritiques de nouvelle-caledonie. Il s'avere qu'elles sont plus elevees dans les sols de plaine qu'en piedmont. Cette difference proviendrait principalement de la presence de ni lie a de la goethite en plaine. En outre, des seuils de toxicite de ni dans la plante et dans la solution ont ete definis. Ainsi, la croissance du mais, au stade 75 cm de haut au niveau de la ligule de la 9#e#m#e feuille degainee, est significativement ralentie lorsque ses parties aeriennes contiennent plus de 12 3 g de ni. G#1 ms. Dans la solution, le seuil defini est un indice de toxicite tenant compte des activites de ni, ca et mg. Les effets toxiques du nickel sur la physiologie du mais sont nombreux. Il apparait que ni diminue principalement l'activite mitotique du meristeme racinaire, soit par une reduction de l'apport de saccharose suite a un blocage de la degradation de l'amidon dans les chloroplastes des cellules de la gaine perivasculaire, soit par une fixation au niveau du meristeme pour en perturber gravement le fonctionnement. Par ailleurs, ni diminue egalement l'activite pompe a protons de l'atpase plasmalemmique des racines. D'autre part, des differences de sensibilite au nickel ont ete mises en evidence entre deux cultivars de mais. Les implications de ces resultats sur la physiologie du mais sont discutees
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Pianelli, Katia. "Recherche des déterminants moléculaires de la tolérance aux métaux lourds dans la plante hyperaccumulatrice Thlaspi caerulescens : Analyse du rôle de la nicotianamine dans la tolérance au nickel". Montpellier 2, 2004. http://www.theses.fr/2004MON20203.
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Belliardo, Catherine. "Etude comparée de la cytogénotoxicité du cadmium, du nickel et de l'aluminium sur le fibroblaste cutané humain". Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0225/document.
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Les métaux sont des éléments chimiques ubiquitaires, naturellement présents dans notre environnement et utilisés dans de nombreux secteurs d’activité tels que, l’aérospatial, la cosmétologie ou l’industrie pharmaceutique. De nombreux travaux montrent qu’ils sont susceptibles d’être à l’origine de diverses pathologies. Toutefois, la diversité et les modalités des études réalisées rendent difficiles la comparaison de leurs effets et mécanisme d’action. Dans ce contexte, ce travail concerne l’étude de la cyto-génotoxicité du cadmium, du nickel et de l’aluminium, sur un même modèle cellulaire, le fibroblaste cutané humain. Leur cytotoxicité est évaluée en étudiant leur effet sur la bioénergétique cellulaire par microcalorimétrie et, leur effet sur la viabilité cellulaire est mesuré par des techniques colorimétriques conventionnelles. Leur génotoxicité est déterminée par des techniques spécifiques que sont le test des comètes et des micronoyaux. De plus, une approche de leur interaction avec l’ADN est réalisée par microcalorimétrie. Les résultats montrent que la cytotoxicité du cadmium est supérieure à celle du nickel, elle-même supérieure à celle de l’aluminium. Seuls le cadmium et le nickel sont génotoxiques à pH7 principalement en induisant un effet aneugène. Leur interaction est de type électrostatique anti-coopérative avec les groupements phosphate de l’ADN. Si l’aluminium à pH7, n’exerce pas d’effet génotoxique, son interaction avec l’ADN à pH acide est comparable à celle du cadmium et du nickel. Ce résultat singulier lié à la valeur du pH suggère l’importance de la prise en compte de la spéciation des métaux pour l’étude de leurs effets aussi bien in vitro qu’in vivoMetals are ubiquitous chemical elements naturally present in our environment and used in many field, like aerospace, cosmetology or pharmaceutical industries. Many works show that metals are involved in diverse diseases. However, the way these studies are led, make the comparison of their effects and mechanism of action delicate. In this context, this work studies the cyto-genotoxicity of cadmium, nickel and aluminum on a single cellular model: normal human dermal fibroblasts. Cytotoxicity is first evaluated by the cell bioenergetics study thanks to microcalorimetry technics, and then the effect on cell viability is measured by conventional colorimetric techniques. Genotoxicity is evaluated by specific technics which are comet and micronuclei assays. Furthermore, thermodynamic properties of the interaction between metals and DNA are determined tanks to microcalorimetry measures. Results show that cadmium cytotoxicity is higher than nickel, itself higher than aluminum. Cadmium and nickel are the only ones genotoxic, they mostly induce aneugenic effects. They present an electrostatic anti-cooperative interaction with DNA phosphate groups. If, at pH 7, aluminum does not induce genotoxicity, his interaction is comparable to cadmium and nickel at acidic pH. This unusual result, related to pH value, highlights the importance of the speciation determination when metal effects are studied, as well in vitro as in vivo
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Forzani, Céline. "Caractérisation de fragments d'ADN de plantes et de "Saccharomyces cerevisiae" conférant à la levure une résistance au nickel". Montpellier 2, 2000. http://www.theses.fr/2000MON20205.
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Le nickel est un metal essentiel pour le developpement des vegetaux, mais peut devenir toxique a de fortes concentrations. Chez les plantes, les mecanismes moleculaires de resistance au nickel sont peu connus. La surexpression de deux adnc de mais chez saccharomyces cerevisiae a confere une resistance au nickel. Aucune difference dans l'accumulation de nickel des levures resistantes n'a ete observee. Le premier adnc code pour une proteine hmg i/y, zmhmg i/y2. Cette proteine contient quatre boites at-hook qui leur permettent d'interagir avec des sequences riches en at de l'adn. Une proteine de fusion gfp-hmg i/y a ete localisee dans le noyau des levures transformees. Les mecanismes de toxicite du nickel sont peu connus, mais semblent impliques un mecanisme epigenetique. Chez les animaux, le nickel augmenterait la condensation de la chromatine aboutissant au silencing de gene se trouvant a proximites. En utilisant des levures avec le gene ura3 insere au telomere, nous avons montre que le nickel ainsi que l'expression de la proteine hmg i/y en levures augmentent le silencing du gene ura3 au telomere. D'autres mutants de levures affectes dans la structure de la chromatine sont plus sensibles au nickel par rapport a la souche sauvage et l'expression de la proteine hmg i/y restaure un phenotype de resistance. Ainsi, il semble que l'expression de la proteine hmg i/y de mais confere une resistance au nickel en alterant la structure de la chromatine limitant ainsi l'acces du nickel a l'adn. Le deuxieme adnc code pour une sous-unite du proteasome 20s, zmpaa. L'abondance du transcrit zmpaa est augmentee dans les feuilles de mais en reponse au nickel. La resistance au nickel pourrait impliquer une degradation des proteines oxydees toxiques par le proteasome 20s.
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Tanios, Carole. "Caractérisation, évaluation de la toxicité du biogaz issu de déchets ménagers et valorisation par reformage catalytique". Thesis, Littoral, 2017. http://www.theses.fr/2017DUNK0474/document.
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Ce travail étudie la récupération de la fraction fermentescible des déchets. En effet, la matière organique se décompose en absence d'oxygène et produit simultanément du biogaz. L'une des technologies émergentes consiste à utiliser le CH₄ et le CO₂, les deux principaux composants du biogaz. C'est la réactionde reformage à sec du méthane (CH₄ + CO₂ → 2 CO + 2 H₂), particulièrement intéressante, car elle se permet de produire un gaz de synthèse avec un rapport H₂/CO proche de 1, avantageux pour plusieurs applications industrielles, et de se débarrasser de deux gaz à effet de serre. Cependant, vu son caractère endothermique, le reformage à sec du méthane nécessite l'utilisation d'un catalyseur, pour éviter d'avoir à opérer à des températures très élevées pour obtenir des conversions suffisantes. De plus, le reformage à sec du méthane s'accompagne de réactions secondaires, dont certaines conduisent à la formation de carbone. Dans ce contexte, les efforts sont orientés vers le développement de systèmes catalytiques ayant une bonne activité et une bonne résistance aux dépôts de carbone. Dans ce travail, des échantillons réels de biogaz sont analysés dans deux centres de biométhanisation, l'un en France et l'autre au Liban. Nos résultats montrent que le vrai biogaz est composé, outre des composants majeurs CH₄ et CO₂, de NH₃, H₂S, de quelques terpènes et de certains COV. Ensuite, des oxydes mixtes de Co, Ni, Mg et Al sont préparés en utilisant la voie hydrotalcite, afin d'obtenir des propriétés catalytiques intéressantes dans le reformage à sec du méthane. L'évaluation des performances catalytiques en présence de certaines impuretés présentes dans le biogaz telles que les composés organiques volatils (toluène) fait également partie de ce travail. Enfin, la toxicité du biogaz issu des centres de biométhanisation est évaluée. Des cultures de cellules pulmonaires humaines (BEAS-2B) sont ainsi exposées à l'interface air/liquide en utilisant le système Vitrocell®. Après exposition des cellules, un ensemble de marqueurs de toxicité est déterminé. Par cette étude, l'impact du biogaz sur la santé humaine sera évaluéThis work studies the energy recovery of the fermentable fraction of waste. Indeed, organic matter decomposes in the absence of oxygen and simultaneously produces biogas. One of the emerging technologies is to upgrade CH₄ and CO₂, the two major components of biogas. This is the dry reforming of methane (CH₄ + CO₂ → 2 CO + 2 H₂) (DRM), which is particularly interesting, since it makes possible to produce a synthesis gas with a H₂/CO ratio close to 1, advantageous for several industrial applications, and to get rid of two greenhouse gases. However, due to its endothermic nature, the dry reforming of methane requires the use of a catalyst, to avoid operating at very high temperatures in order to obtain sufficient conversions. Moreover, the dry reforming of methane is accompanied by secondary reactions, some of which lead to the formation of carbon. In this context, efforts have been focused on the development of catalytic systems with good activity and good resistance against carbon deposition. In this work, real biogas samples were analyzed at two biomethanation centers, one in France and the other in Lebanon. Thus, knowing the identity and the quantity of the various compounds, a study of their effect on the efficiency of the catalyst is done. Our results show that the real biogas is composed, besides the major components, CH₄ and CO₂, of NH₃, H₂S, some terpenes ans some VOCs. In addition, mixed oxides of Co, Ni, Mg and Al were prepared using the hydrotalcite route, in order to obtain interesting catalytic properties. The prepared systems were characterized by different physicochemical techniques and tested in the dry reforming of methane. The Co-Ni based system seems to be the best system joining the high activity of nickel with the high resistance of cobalt towards carbon deposition. The evaluation of the catalytic performances in the presence of some impurities that exist in biogas quch as volatile organic compounds (toluene) is also a part of this work. Finally, the toxicity of biogas collected from biomethanation centers was evaluated. Human lung cell cultures (BEAS-2B) were thus exposed at the air / liquid interface using the Vitrocell® system. After exposure of the cells, a set of toxicity markers is determined. In this study, the impact of biogas on human health will be evaluated
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Vassas-Jardel, Aude. "Activités biologiques d'organismes marins par tests moléculaires in vitro : étude particulière de corallistes undulatus et aplidium longithorax". Montpellier 1, 1996. http://www.theses.fr/1996MON13522.
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Hulo, Sébastien. "Le condensat d'air exhalé : une nouvelle matrice pour évaluer l'exposition pulmonaire professionnelle". Phd thesis, Université du Droit et de la Santé - Lille II, 2014. http://tel.archives-ouvertes.fr/tel-01060978.
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Dans le cadre d'une action préventive, la mesure de la dose interne pulmonaire est plus pertinenteque la mesure de l'exposition atmosphérique car la dose interne est la quantité de toxique pouvantinteragir avec les cellules de l'épithélium respiratoire. En santé-travail, le dosage urinaire est fréquemmentutilisé mais il ne représente que le résultat final de l'épuration de multiples organes. Lecondensat d'air exhalé (EBC) est le liquide obtenu de façon non invasive après refroidissement del'air expiré d'un sujet au repos. Ce liquide est constitué de l'aérosolisation du liquide recouvrantl'épithélium respiratoire du compartiment alvéolaire et aussi du compartiment trachéobronchique oubronchique. Nous proposons d'utiliser l'EBC comme une approche alternative pour la surveillancebiologique des salariés. Les modèles cinétiques d'épuration pulmonaire actuels montrent que lesparticules déposées dans le compartiment alvéolaire ont une épuration très lente. Nous avons doncvoulu savoir si l'EBC était une matrice reflétant l'exposition pulmonaire en particules inhalées.Objectifs : 1) évaluer la faisabilité de la détection de particules minérales ou métalliques dans l'EBCde salariés exposés, 2) corréler la concentration de ces particules dans l'EBC avec les concentrationsatmosphériques de ces particules obtenues pendant le poste de travail et avec les dosages urinaires.Matériel et Méthode : Nous avons analysé les EBC de salariés issus de trois secteurs d'activitéprofessionnelle. La 1ère étude concernait un salarié d'une unité de broyage de muscovite atteintd'une infiltration pulmonaire diffuse. La 2ème étude était une étude " exposé/non-exposé "concernant un groupe de soudeurs utilisant la technique " metal inert gaz " (MIG). La 3ème étudeétait une étude " exposé/non-exposé " de salariés exposés à des composés solubles de bérylliumdans le secteur de l'aluminerie dans 2 entreprises différentes.RésultatsEtude n°1 : L'analyse minéralogique de l'EBC a retrouvé des particules ayant le même profil spectralen spectrométrie Raman que les particules prélevées dans l'atmosphère de l'entreprise. L'analyseminéralogique du parenchyme pulmonaire a montré la présence d'une concentration élevée departicules compatibles avec des particules de muscovite.Etude n°2 : Les concentrations de manganèse et de nickel dans l'EBC (Mn-EBC, Ni-EBC) dosées parICP-MS étaient significativement plus élevées chez les soudeurs que chez les témoins alors que cettedifférence n'était pas significative pour le Mn urinaire (Mn-U). Les concentrations de Mn-EBC et deNi-EBC ne sont pas corrélées avec leur concentration respective dans l'urine. Les régressionslinéaires ont trouvé des coefficients significativement positifs entre les concentrations de Mn-EBC,Ni-EBC, Ni-U et Cr-U et les indices d'exposition cumulée.Etude n°3 : Les concentrations de béryllium et d'aluminium dans l'EBC (Be-EBC, Al-EBC) étaientsignificativement plus élevées chez les sujets de l'entreprise n°1 que chez les témoins alors que leursconcentrations dans les urines ne l'étaient pas. Les régressions linéaires ont trouvé des coefficientssignificativement positifs entre les concentrations de Be-EBC et celle d'Al-EBC mais aussi entre lesconcentrations de Be-EBC et l'indice d'exposition cumulée. Les concentrations d'Al-EBC et Al-Uétaient significativement plus élevées chez les sujets de l'entreprise n°2 que chez les témoins. [...]
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Doumandji, Zahra. "Identification de marqueurs d’exposition et d’effets de nanoparticules métalliques sur modèle in vitro". Thesis, Université de Lorraine, 2019. http://www.theses.fr/2019LORR0067.
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En conséquence de l'extension de l’utilisation des nanoparticules dans différents secteurs industriels, le nombre de travailleurs potentiellement exposés ne cesse de croître, sans parfaitement connaître les propriétés toxicologiques de ces matériaux. Étant donné que les nanoparticules peuvent se trouver en suspension dans l’atmosphère professionnelle, l'inhalation représente une voie d'exposition professionnelle majeure. De ce fait, l’évaluation des risques liés à l’exposition aux nanomatériaux requiert d’entreprendre des études de toxicologie sur des modèles cellulaires des voies aériennes. Dans ce manuscrit, les réponses cellulaires et moléculaires des macrophages alvéolaires de rat (NR8383) exposés à des nanoparticules d’oxydes métalliques : ZnO, ZnFe2O4, NiZnFe2O4, Fe2O3, TiO2-NM105 et TiO2-NRCWE001, ont été étudiées, en combinant des analyses toxicologiques classiques (caractérisation des nanoparticules par microscopie électronique à transmission et par diffusion dynamique de la lumière, évaluation de la cytotoxicité par tests WST-1 et libération de LDH); et de criblage moléculaire à haut débit (analyses de transcriptomique et de protéomique). Des cellules NR8383 ont été exposées aux nanoparticules ZnO, ZnFe2O4, NiZnFe2O4, Fe2O3, TiO2-NM105 et TiO2-NRCWE001 pendant 24 h ce qui a permis de déterminer une dose sub-toxique pour chaque nanoparticule à laquelle les macrophages ont été exposés pour l’analyse moléculaire. Quatre heures suite à l’exposition des cellules aux nanoparticules, de nombreux gènes et protéines étaient différentiellement exprimés. Le stress oxydant était la réponse biologique adverse suite à l’exposition des cellules aux nanoparticules composées de zinc. En revanche, l’inflammation était la principale voie activée dans les cellules exposées à la forme anatase et rutile des nanoparticules de TiO2. En conclusion, cette étude expose les « empreintes biologiques » des deux groupes de nanoparticules d’intérêt. Enfin, notre étude combinée à des travaux antérieurs de la littérature pourraient aussi être profitables pour valider les biomarqueurs d’exposition et d’effets aux nanomatériaux suggérés afin de prédire les effets biologiques adversesAs a consequence of the extension of the use of nanoparticles in different industrial sectors, the number of potentially exposed workers continues to grow, without fully knowing the toxicological properties of these materials. Since nanoparticles can be aerosolized in the occupational atmosphere, inhalation is the major occupational exposure route. For this reason, risk assessment of exposure to nanomaterials requires toxicology studies to be conducted on cellular models of the airways. In this manuscript, the cellular and molecular responses of rat alveolar macrophages (NR8383) exposed to metallic oxide nanoparticles: ZnO, ZnFe2O4, NiZnFe2O4, Fe2O3, TiO2-NM105 and TiO2-NRCWE001, were studied, combining conventional toxicological analyzes (characterization of nanoparticles by transmission electron microscopy and dynamic light scattering, evaluation of cytotoxicity by WST-1 assays and LDH release); and high throughput molecular screening (transcriptomic and proteomic analyzes). NR8383 cells were exposed to the ZnO, ZnFe2O4, NiZnFe2O4, Fe2O3, TiO2-NM105 and TiO2-NRCWE001 nanoparticles for 24 h which allowed for the determination of a sub-toxic dose for each nanoparticle to which the macrophages were exposed for molecular analysis. Four hours after exposure NR8383 to nanoparticles, many genes and proteins were differentially expressed. Oxidative stress was the adverse biological response following exposure of cells to nanoparticles composed of zinc. In contrast, inflammation was the main activated pathway in cells exposed to the anatase and rutile form of TiO2 nanoparticles. In conclusion, this study exposes the "biological fingerprints" of the two groups of nanoparticles of interest. Finally, our study, combined with previous literature studies, could also be beneficial in validating biomarkers of exposure and effects of nanomaterials suggested in order to predict adverse biological effects
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Pétriglieri, Jasmine Rita. "Alteration of asbestiform minerals under sub-tropical climate : mineralogical monitoring and geochemistry. The example of New Caledonia". Electronic Thesis or Diss., Nouvelle Calédonie, 2017. http://portail-documentaire.unc.nc/files/public/bu/theses_unc/These_Jasmine_Petriglieri-derniere_version_these.pdf.
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Sous climat humide tropical ou subtropical, les processus d'altération supergène sont les principaux responsables de la formation et de la libération des fibres d'amiante dans l’environnement. Plus du tiers de la Nouvelle Calédonie est recouvert d’unités ultrabasiques altérées, riches en minerai de Ni. L’exploitation minière du Ni doit composer avec la présence d’affleurements d’amiante et de minéraux fibreux de type serpentine et amphibole. Dans ce contexte, les sociétés minières doivent prévenir les risques sanitaires liés à l'exposition environnementale aux fibres minérales. Actuellement, il n'existe pas de technique analytique capable de caractériser instantanément une fibre d'amiante in situ, en fournissant des informations sur la distribution de taille, la morphologie, la composition chimique et le degré d'altération associés. Cependant, la connaissance de tous ces paramètres est nécessaire pour évaluer le risque sanitaire associé à l'exposition. L'utilisation des dispositifs portable tels quels la Microscopie Optique à Lumière Polarisée (MOLP) et la spectrométrie Raman représente la stratégie la plus efficace pour améliorer l'acquisition et l'interprétation des données, y compris pour les échantillons fortement fibreux et altérés. De plus, des analyses géochimiques préliminaires ont révélé que l'effet mécanique de la circulation des fluides entre les fibres et lamelles, associé à la lixiviation chimique des éléments à l'interface roche/eau, favorisent la dissociation des fibres et leur libération dans l'environnement. Un focus a été réalisé sur l'antigorite fibreuse, reconnue comme amiante uniquement dans la réglementation calédonienneUnder humid tropical to sub-tropical conditions, weathering processes and supergene mineralization are the main responsible for genesis and release of asbestos fibres. The New Caledonia is one of the largest world producers of Ni ore that is formed by the alteration of ultramafic rocks. Almost all outcrops of geological units and open mines contain serpentine and amphibole, also as asbestos varieties. Mining companies must therefore deal with the health concerns related to environmental exposure to mineral fibres. At present, there is not a technique capable to instantly characterize an asbestos fibre in situ, providing information about size and distribution, morphology, chemical composition and alteration grade. However, the acquisition of all these parameters is necessary for determining the health risk associated to fibre exposition. The employment of specialized tools such as Polarized Light Microscopy associated to Dispersion Staining (PLM/DS) and portable Raman spectroscopy has proved extremely effective in the improvement of performance and rapidity of data acquisition and interpretation, even in the presence of strongly fibrous and altered samples. Regardless of the alteration state, a great variability in morphology was observed (SEM investigation). Preliminary geochemical analyses have proved that the physical-mechanical effect of fluid circulation within the porous of fibres and lamellae, associated to chemical elemental exchange at rock/waters interface, favoured the dissociation of fibres and their release in the environment. A focus was set on fibrous antigorite, recognized as asbestos only by Caledonian legislation, but still not by European law
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Basson, Rozell. "Heat shock protein 70 and cortisol as biomarkers for cadmium, chromium and nickel contamination in Oreochromis mossambicus". Thesis, 2008. http://hdl.handle.net/10210/1012.
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South Africa is one of the countries with the largest mining operations in the world. Most of these mines make use of natural dams and rivers in their water supply, which often are being pumped back into the natural environment. The reticulated water pumped back into the system may contain high concentrations of dissolved chemicals, which may lead to the reduction of the endemic organisms. Many of the heavy metals mined in South Africa are highly toxic at very low concentrations, and it is therefore very important to do frequent analysis on the aquatic environment. The value of chemical analysis per se has become limiting, as chemical analysis supplies information on the levels of chemicals at a certain time, and the new trend is to incorporate biological monitoring into existing monitoring strategies. Heat shock proteins are classified as stress proteins and are primarily expressed under stressful conditions, therefore having the potential to be used as possible biomarkers. Cortisol, also a known stress hormone, has been suspected of suppressing the expression of heat shock proteins by replacing the heat shock protein on the glucocorticoid receptor. This leads to reduced levels of heat shock proteins in the organism through a negative feedback mechanism. However, before information on heat shock proteins and cortisol can be successfully incorporated into ecological risk assessment, an understanding of how cortisol influences heat shock protein levels after heavy metal exposure is needed. This study aims to determine what effect cortisol had on the production of a specific member of the Hsp70 class of heat shock proteins at different time intervals after exposure of Oreochromis mossambicus to various metals. Proteins were determination using the Bradford method, while protein separation was done using Sodium Dodecyl Sulphate-Polyacrylamide Gel Electrophoresis. Thereafter, separated proteins were subjected to Western blotting and immunoblotting in order to quantify the different Hsp70 family members in the hepatic tissue. Cortisol levels were determined using a commercially available Cortisol ELISA Test Kit. Hsp70 accumulation occurred in only two exposure groups, namely the cadmium and chromium exposure groups. Accumulation of Hsp70 demonstrated an increase in accumulation rates at the 24 hour time interval of the 10% cadmium exposure group, with accumulation remaining relatively constant in the 20% cadmium exposure group. Accumulation of Hsp70 occurred only at the 48 and 96 hour time intervals in the 10% chromium exposure group. The accumulation of Hsp76 and Hsp74 were observed to follow the same pattern throughout the 96 hour exposure. In the 10% exposure groups accumulation of both Hsp76 and Hsp74 indicated an increase in accumulation rates at the 72 hour of groups exposed to chromium and nickel, whereas the accumulation of Hsp76 and Hsp74 remains constant after exposure to cadmium. In the 20% cadmium exposure group, an increase in Hsp76 and Hsp74 accumulation was observed at the 24 hour time interval, whereby accumulation of Hsp76 and Hsp74 remains constant in both the chromium and nickel 20% exposure groups. Males accumulated higher levels of Hsp70 members than females in the cadmium and chromium exposure groups. In the 10% exposure groups the females accumulated higher levels of Hsp74, whereas the males accumulated higher levels of Hsp74 in the 20% exposure groups. Accumulation of Hsp76 proved to be higher in the females in all exposure groups, compared to the males. Cortisol concentrations remained constant throughout the 96 hour exposure period, with higher cortisol levels observed in the chromium exposure groups. Cortisol concentrations proved to increase at higher concentrations of metal exposure. Cortisol proved to have no significant effect on Hsp70 family member accumulation, except in the cadmium exposure group, where a negative regression was observed. Accumulation of the HSp70 member can be linked to possible metal specificity, due to the fact that Hsp70 accumulated in only two metal species (cadmium and chromium). However, the accumulation of Hsp76 and Hsp74 may possibly prove that the higher concentrations of specific metals leads to early accumulation of heat shock proteins. The higher accumulation levels of Hsp70 in males, compared to accumulation levels in females may be due to the greater need to discard damadged or denatured proteins, whereas higher Hsp74 and Hp76 accumulation levels in females, may be due to the higher levels of reproductive proteins present in females, compared to males. This study therefore concluded that cortisol may have no significant effect on the accumulation of the Hsp70 family members in the liver of fish.Prof. J.H.J. Van Vuren
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"A quantitative and qualitative histological assessment of selected organs of Oreochromis mossambicus after acute exposure to cadmium, chromium and nickel". Thesis, 2010. http://hdl.handle.net/10210/3219.
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M.Sc.South Africa is renowned for its exploitable mineral resources and continues to be a major player in the world’s mineral markets. The country is well known for containing the world’s largest gold and platinum repositories and electroplating industries, which is the major cause for delivering by-products such as cadmium (Cd), chromium (Cr) and nickel (Ni). Environmental pollution caused by active mining and seepage from closed mines, continuously threatens South African water resources. Such pollution can cause a shift in water chemistry and increase the availability of certain metals to the living organisms of such a system. Even at low concentrations metals are amongst the most toxic environmental pollutants. As a result of their persistence and capacity to accumulate in the environment, metals have a lasting detrimental effect on the ecosystem. Although there is progress in the treatment of metallic wastes, the discharge thereof by industries is still a serious water pollution problem. In the past, chemical analysis of water has proven to be of great use for the detection of pollutants within the environment. The value of chemical analysis alone has become limiting, as chemical analysis supplies information on the levels of chemicals at a certain time. Furthermore, the monitoring of water quality variables often does not reflect long-term events that may play a critical role in determining the ecosystem health. It is now generally understood that measurements of only the physical and chemical attributes of water cannot be used as surrogates for assessing the health of an aquatic ecosystem. The new trend is to incorporate biological monitoring into Abstract existing monitoring strategies. Fish are entirely dependent on the aquatic environment for their survival, rendering them a good monitor of water pollution. Macroscopic changes in organs are preceded by changes at the tissue, cellular or molecular level. These changes are the net result of adverse biochemical and physiological changes within an organism. Histological analysis is a therefore very sensitive parameter and a valuable technique in determining cellular changes in target organs as a result of exposure to stressors. Fish histology can thus be used as an indicator of exposure to contaminants and assess the degree of pollution. Because of the subjective nature of morphological studies correlations with other quantitative studies are difficult. However, incorporation of quantitative methods is essential to the continued development of histopathology as a biomarker of pollution exposure, and to the interpretation of histological responses. The aim of this study is to qualitatively and quantitatively describe the toxic induced histological changes in the selected organs of Oreochromis mossambicus after acute exposure to Cd, Cr and Ni. Fish were exposed to 10% (n=20) and 20% (n=20) of the LC50 concentration of Cd, Cr and Ni respectively under controlled conditions (23 ± 1°C) for 96 hours in an environmental room with a control group (n=5) for each exposure.
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Giri, Nitai Charan. "Structural investigations of early intermediates and nickel inhibition complexes of human DNA and histone demethylases". 2013. https://scholarworks.umass.edu/dissertations/AAI3589025.
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The toxicity of nickel compounds is most clearly demonstrated in nickel refinery workers. Nickel exposure leads to lung and nasal cancers and increased risk of acute respiratory syndromes. The toxicity of nickel compounds has been attributed to its roles in oxidative damage, changes in gene expression by an epigenetic mechanism, and inhibition of iron containing enzymes. For this reason, we are interested in the mechanisms of nickel induced inhibition of some of these enzymes. Non-heme iron enzymes carry out a broad number of essential biological reactions in mammalian metabolism, including several that are involved DNA repair and histone demethylation, and thus are involved in gene expression by an epigenetic mechanism. The enzymes involved in DNA repair (e.g., ABH2) and histone demethylation ( e.g., JMJD2 proteins) require Fe(II) and αKG for their function. The replacement of Fe(II) in the active site by other metal ions, including Ni(II), produces an inactive enzyme. Cellular DNA undergoes alkylation damage by chemicals that modify DNA bases and this damage can be inherited. Cells have evolved systems to repair this DNA alkylation damage. In human, ABH2 repairs endogenously formed 1-methyladenine (1-MeA) and 3-methylcytosine (3-MeC). Our experiment suggests that nickel inhibits ABH2 in a dose dependent manner. The inactivation of ABH2 will lead to increased DNA methylation and subsequent transcriptional silencing, which can result in caner and other developmental defects. Histone tails undergo a number of posttranslational modification including acetylation, methylation, phosphorylation and ubiquitination. Differential methylation of histone H3 and H4 lysyl residues regulates processes including heterochromatin formation, X-chromosome inactivation, DNA repair and transcriptional regulation. The increase in cellular nickel concentration leads to an increase in the global levels of H3K9Me1 and H3K9Me2 – not by affecting histone methyltransferases, but by inhibiting a group of Fe(II) and αKG dependent histone demethylases. Using JMJD2A and JMJD2C as examples, we show that JMJD2 family of histone demethylases is also highly sensitive to inhibition by Ni(II) ions. Isothermal titration calorimetry (ITC) has been used to understand the binding of Fe(II) and Ni(II) to ABH2. Our ITC results indicate that both Fe(II) and Ni(II) form 1:1 complexes with ABH2, but Ni(II) binds ABH2 stronger than Fe(II). X-ray absorption spectroscopy (XAS) has been used as a structural probe of the active site metal center in WT-recombinant ABH2, truncated JMJD2 proteins (1 – 350 aa) and Ni(II)-substituted WT-recombinant ABH2 and JMD2 proteins in the presence and/or absence of αKG and substrate in order to examine the reaction mechanism and ascertain the intermediate(s) affected by nickel substitution. Our XAS results indicate that in the presence of both αKG and substrate the iron site is five coordinate while the nickel site is six coordinate and thus, nickel site does not have any empty coordination site for oxygen binding and activation. Thus, using ABH2 and JMJD2 proteins as examples, we show that Fe(II) and αKG dependent enzymes are inhibited by Ni(II) ions. This is consistent with previous reports in literature on other Fe(II) and αKG dependent enzymes. Our results indicate that Ni(II) inhibits ABH2 and JMJD2 proteins by replacing the active site metal and both electronic and steric components are involved. Inhibition of some of these non-heme iron enzymes, like histone demethylases may be one way nickel can alter gene expression by an epigenetic mechanism.
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Muleja, Adolph Anga. "Phosphine derivatized multiwalled carbon nanotubes for the removal of nickel and platinum from solutions". Thesis, 2012. http://hdl.handle.net/10210/4677.
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M.Tech.Studies on the removal of nickel and platinum are increasing due to the toxicities of these metals. Several methods are currently used to extract these metals however they present limitations. There is hence a need to develop an efficient method for the removal of nickel and platinum from aqueous solution. A study on the use of purified multiwalled carbon nanotubes (purified MWCNTs) and a phosphine derivatized multiwalled carbon nanotubes for the extraction of these metal ions from solution was therefore undertaken. Multiwalled carbon nanotubes (MWCNTs) were produced by nebulised spray pyrolysis, purified by a multi-step technique and functionalized. Phosphine moieties were attached to the bromoarylated- MWCNTs by metallated phosphide route leading to triphenylphoshine linked MWCNTs (Tpp-MWCNTs). As produced, purified and triphenylphosphine linked multiwalled carbon nanotubes were characterized by various techniques, including microscopic and spectroscopic techniques, thermal, elemental and surface analysis. Transmission and scanning electron microscopy used revealed purified MWCNTs had insignificant impurities. X-ray photoelectron spectroscopy (XPS) results showed that triphenylphosphine linked multiwalled carbon nanotubes had 2.6% phosphorus. Zeta potential results demonstrated that purified MWCNTs had positive surface charges at acidic pH. Triphenylphosphine linked multiwalled carbon nanotubes were negatively charged on the surface in acidic media. Batch adsorption experiments were carried out to investigate the removal of nickel and platinum from aqueous solutions. Several parameters which influence the adsorption process were studied, including the effect of pH, the contact time and the effect of initial concentration on adsorption. The adsorption models for the Freundlich and Langmuir isotherms were employed to fit the experimental data. Triphenylphosphine linked MWCNTs removed more nickel (84.68 mg/g) than purified MWCNTs (77.39 mg/g). In contrast, purified MWCNTs removed more platinum (10.5 mg/g) than triphenylphosphine linked MWCNTs (6.01 mg/g). Experimental data for nickel fitted both Freundlich and Langmuir models well whereas only Langmuir model fitted well for platinum. The adsorption of nickel and platinum was indeed found to be pH, time and initial concentration dependent. Metal species (nickel and platinum) in solution had also influenced the uptake of these metals using purified-and Tpp-MWCNTs.
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Norwood, Warren Paul. "Metal Mixture Toxicity to Hyalella azteca: Relationships to Body Concentrations". Thesis, 2007. http://hdl.handle.net/10012/3559.
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A literature review of metal mixture interaction analyses identified that there was not a consistent method to determine the impact of metal mixtures on an aquatic organism. The review also revealed that a majority of the research on mixtures made use of water concentrations only. Therefore research was conducted to determine the relationship between exposure, bioaccumulation and chronic effects of the four elements As, Co, Cr and Mn individually. Mechanistically based saturation models of bioaccumulation and toxicity were determined for the benthic invertebrate Hyalella azteca, from which lethal water concentrations and body concentrations were also determined. These models were then combined with those previously done for the metals Cd, Cu, Ni, Pb, Tl and Zn to model the impact of 10 metal mixtures on bioaccumulation in short term (1-week) exposures and on bioaccumulation and toxicity in chronic (4-week) exposures at “equi-toxic” concentrations. Interactions between the metals were identified in which; Cd, Co and Ni bioaccumulations were significantly inhibited, Tl and Zn bioaccumulations were marginally inhibited, there was no impact on Cr, Cu or Mn bioaccumulation, and both As and Pb bioaccumulation were enhanced by some mixtures of metals. It was determined that strict competitive inhibition may be a plausible mechanism of interaction affecting Co, Cd and Ni bioaccumulation but not for any of the other metals. However, it is possible that other interactions such as non-competitive or anti-competitive inhibition may have been responsible.
A metal effects addition model (MEAM) was developed for Hyalella azteca based on both the bioaccumulation (body concentrations) to effects and the exposure (water concentration) to effects relationships developed from the single metal only studies The MEAM was used to predict the impact of metal mixture exposures on mortality. Toxicity was under-estimated when based on measured water or body concentrations, however, its best prediction was based on body concentrations. The MEAM, when based on measured body concentrations, takes bioavailability into account, which is important since the chemical characteristics of water can greatly alter the bioavailability and therefore toxicity of metals.
The MEAM was compared to the traditional Concentration Addition Model (CAM), which calculates toxic units based on water concentrations and LC50s or body concentrations and LBC50s. The CAM overestimated toxicity, but had its best prediction when based on water concentrations. Over all, the best fit to observed mortality was the prediction by the MEAM, based on body concentrations. The measurement of bioaccumulated metals and the use of the MEAM could be important in field site assessments since it takes into account changes in bioavailability due to different site water chemistries whereas the traditional CAM based on water concentration does not.