A mucopolissacaridose tipo VI (MPS VI) ou Síndrome de Maroteaux-Lamy, é uma doença autossômica recessiva causada pela deficiência da enzima lisossomal Nacetilgalactosamina- 4-sulfatase (ARSB), a qual resulta no armazenamento lisossômico de dermatan sufato em vários tecidos e órgãos, dando origem a uma condição clínica de espectro variável, desde formas mais graves até formas mais atenuadas. O acúmulo de substrato não degradado causa um importante comprometimento ósseo, problemas respiratórios, baixa estatura e outros problemas, afetando os olhos, o coração e outros órgãos. Embora a síndrome de Maroteaux-Lamy não tenha uma incidência definida no Brasil, é reconhecido que, no nosso meio, é muito mais freqüente do que em outros países e regiões. Ela é particularmente freqüente no município de Monte Santo (Bahia), de aproximadamente 50.000 habitantes e onde já foram registrados 13 casos da doença. O diagnóstico é importante porque existe hoje um tratamento específico para a doença, a terapia de reposição enzimática (TRE), que vem mostrando bons resultados, especialmente quando iniciada em idade precoce. Descrevemos neste trabalho uma adaptação para microplacas da medida fluorimétrica da atividade de ARSB, e uma nova metodologia de análise molecular, ambas padronizados para sangue total impregnado em papel-filtro (STIPF). Essas técnicas foram desenvolvidas para incluir um teste de triagem neonatal para MPS VI, realizado nas amostras coletadas para o “teste do pezinho” nos neonatos do município de Monte Santo. Esses métodos permitem a detecção de pacientes com MPS VI e dos portadores da mutação específica que parece ser responsável pela alta incidência de MPS VI nessa localidade, uma vez que todos os pacientes lá diagnosticados apresentavam a mesma mutação (p.H178L) em homozigose. O trabalho foi desenvolvido em três etapas: na primeira foi realizada a padronização das técnicas em 100 amostras de STIPF; na segunda foi feito um teste-piloto com amostras de neonatos de Monte Santo, para avaliação das técnicas padronizadas e para o estudo de termoestabilidade em controles hígidos; na terceira foram analisadas amostras de STIPF de neonatos provenientes de Monte Santo pelos dois métodos (bioquímico e molecular). A padronização para realização da medida fluorimétrica da atividade enzimática de ARSB em microplacas indicou que o método é sensível, permitiu diferenciar os valores da população normal dos valores dos pacientes afetados e possibilitou a identificação segura de pacientes com MPS VI. Nas padronizações da análise molecular da mutação p.H178L em STIPF foi possível diferenciar os indivíduos normais, heterozigotos e homozigotos. Os resultados preliminares disponíveis indicam que o protocolo de triagem neonatal para MPS VI desenvolvido no presente trabalho poderá ser facilmente incorporado por laboratórios de referência, contribuindo para a detecção e tratamento precoce dos pacientes afetados por MPS VI. / Mucopolysaccharidosis type VI (MPS VI) or Maroteux-Lamy syndrome, is an autosomal recessive disorder caused by deficiency of the lysosomal enzyme Nacetylgalactosamine- 4-sulfatase (ARSB), which results in lysosomal storage of dermatan sufate in various tissues and organs and leads to a variable clinical spectrum, including more severe and attenuated forms. The accumulation of undegraded substrate causes bone involvement, respiratory problems and short stature, among other signs and symptoms, affecting the eyes, heart and other organs. Although the Maroteaux-Lamy syndrome does not have a defined incidence in Brazil, it is recognized that in our environment it is much more frequent than in other countries and regions. It is particularly frequent in the municipality of Monte Santo (Bahia) approximately 50,000 inhabitants and where there have already been 13 cases of the disease. The diagnosis is important because today there is a specific treatment for the disease, enzyme replacement therapy (ERT) which has shown good results, especially when started at an early age. We describe herein the standardization of the microplate fluorometric method for the ARSB test and a new methodology of molecular analysis, both adapted for dried blood spots (DBS) samples. These techniques were developed for inclusion of MPS VI in the newborn screening program that already tests the neonates of the city of Monte Santo, Bahia, Brasil for metabolic diseases. The methods were developed to detect patients with MPS VI and also for carriers, once the disease seems to have a high incidence (around 1:5.000) at this location. Also, all patients that have already been diagnosed in this city presented the same mutation (p.H178L) in homozygosis. The study was conducted in three stages: in the first was performed in 100 DBS samples an standardization of the techniques; in the second was done a pilot test with samples of newborns of Monte Santo, for the evaluation of standardized techniques and for the thermostability study in healthy controls; in the third were analyzed newborns samples from Monte Santo for both biochemical and molecular methods. Standardization on microplate for fluorimetric enzyme activity of the ARSB showed the assay sensitivity, differentiating values between normal and affected and allowing a reliable detection of patients with MPS VI. On the standardization for molecular analysis in DBS it was possible to differentiate the results for normal individuals, heterozygous and affected for the mutation p.H178L. The preliminary results available indicate that the protocol of neonatal screening for MPS VI developed in this work can be easily incorporated by reference laboratories, contributing to the detection and premature treatment of MPS VI affected patients.

Les matériaux cimentaires sont largement utilisés dans la conception et la construction des sites de stockage de déchets radioactifs. Une des manières d’améliorer leur performance est d’introduire des adjuvants organiques dans la structure. La présence de matière organique dans l’eau porale peut affecter la mobilité des radionucléides : les molécules organiques forment des complexes solubles et peuvent être en compétition avec les radionucléides au niveau des sites de sorption. Ce travail avait pour but de comprendre les mécanismes de telles interactions au niveau moléculaire. Le système modèle a trois composantes. D’abord, des phases C-S-H ont été choisies en tant que modèles du ciment.Ensuite, le gluconate est sélectionné en tant que modèle d’additif organique pour sonder les mécanismes d’interaction à l’échelle moléculaire. Un système plus complexe impliquant un superplastifiant (PCE) a été testé. La troisième espèce, U(VI), est représentative d’un radionucléide de la série des actinides. Le développement de la description des effets de postproduction des espèces organiques pour les applications de stockage des déchets radioactifs était l’objectif principal de ce travail. L’étude des systèmes binaires fournit des données de référence pour l’investigation de systèmes ternaires C-S-H/matière organique/U(VI) plus complexes. Des cinétiques et des isothermes de sorption/désorption pour les espèces sur les C-S-H sont mesurés. En parallèle, des modèles atomiques ont été développés pour les interfaces d’intérêt. Les aspects structuraux, énergétiques et dynamiques des processus de sorption sur les surfaces de ciment sont modélisés par la technique de la dynamique moléculaire. / Cementitious materials are extensively used in the design and construction of radioactive waste repositories. One of the ways to enhance their performance is to introduce organic admixtures into the cement structure. However, the presence of organics in the pore water may affect the radionuclide mobility: organic molecules can form water-soluble complexes and compete for sorption sites. This work was designed to get detailed understanding of the mechanisms of such interactions on the molecular level. The model system has three components. First, pure C-S-H phases with different Ca/Si ratios were chosen as a cement model. Secondly, gluconate (a simple well-described molecule) is selected as a good starting organic additive model to probe the interaction mechanisms on the molecular scale. A more complex system involving polycarboxylate superplasticizer (PCE) was also tested. The third, U (VI), is a representative of the actinide radionuclide series. The development of description of the effects of organics for radioactive waste disposal applications was the primary objective of this work. The study of binary systems provides reference data for the investigation of more complex ternary (C-S-H/organic/U(VI)). The interactions are studied by means of both experimental and computational molecular modelling techniques. Data on sorption and desorption kinetics and isotherms for additives and for U (VI) on C-S-H are acquired in this work. In parallel, atomistic models are developed for the interfaces of interest. Structural, energetic, and dynamic aspects of the sorption processes on surface of cement are quantitatively modeled by molecular dynamics technique.

Dans le but d’élucider la chimie de coordination et la structure des complexes formés avec des ligands organiques de la famille des sidérochélates, des études physico-chimiques sur la complexation du fer(III), de certains lanthanides(III) (La3+, Nd3+, Sm3+, Eu3+, Gd3+, Ho3+, Lu3+) et de l’uranium(VI) ont été effectuées. La connaissance des propriétés de complexation sidérophore-actinide est une étape essentielle pour appréhender le comportement à long terme d'un sol contaminé par des radioéléments. Trois acides dihydroxamiques synthétisés au laboratoire ((LCyEt)2–, (LCyPr)2– et (LO)2–) mimant un sidérophore d’origine fongique, l’acide rhodotorulique, ont été évalués pour la chélation du fer(III) par des titrages potentiométriques éventuellement couplés à une détection spectrophotométrique en milieu KNO3 0,1 M. Ces mesures ont permis de confirmer la présence de complexes di- et trileptiques dans les conditions d’excès du ligand. Le modèle chimique comprend au total cinq espèces de formule [Fem(L)lHh](3–2l+h)+ : [Fe(L)]+, [Fe(L)(OH)], [Fe(L)(OH)2]–, [Fe(L)2H] et [Fe2(L)3]. Le traitement numérique des données spectrophotométriques collectées dans le visible nous a conduit à proposer le spectre électronique pour chacune des espèces identifiées. En outre, la spectroscopie de masse par ionisation électrospray (ESI-MS) a confirmé la formation des espèces mono- ([Fe(L)]+) et dileptiques ([Fe(L)2H]). L’étude potentiométrique du ligand dihydroxamique abiotique (LCyPr)2– en présence de sept lanthanides trivalents a permis de proposer un modèle chimique comprenant cinq espèces mono- et dileptiques ([Ln(LCyPr)]+, [Ln(LCyPr)H]2+, [Ln(LCyPr)2]−, [Ln(LCyPr)2H]) et une espèce monohydroxylée [Ln(LCyPr)OH] en milieu KNO3 0,1 M. Par ailleurs, les mesures potentiométriques et spectrophotométriques pour le système UO22+/(LCyPr)2– suggèrent la formation à l’équilibre de cinq complexes d’uranium(VI) entre p[H] 2 et 10. Le modèle comprend les complexes mono- et dileptiques suivants : [UO2(LCyPr)], [UO2(LCyPr)H]+, [UO2(LCyPr)OH]−, [UO2(LCyPr)2]2− et [UO2(LCyPr)2H]−. La combinaison de ces deux techniques nous a permis d’appréhender la spéciation de ce radionucléide en milieu KNO3 0,1 M et de proposer des schémas de coordination pour les différentes espèces mises en évidence / With the aim of elucidating the coordination chemistry and the structure of the complexes formed with organic ligands belonging to the family of siderochelates, physico-chemical studies of the complexation of iron(III), some lanthanides(III) (La3+, Nd3+, Sm3+, Eu3+, Gd3+, Ho3+, Lu3+) and uranium(VI) have been performed. The knowledge of the properties of actinide-siderophore complexes is an essential step to assess long-term behavior of soils contaminated by actinides. Three dihydroxamic acids synthesized in our laboratory ((LCyEt)2–, (LCyPr)2– and (LO)2–) mimicking a fungal siderophore, rhodotorulic acid, have been evaluated with respect to iron(III) chelation by potentiometric and spectrophotometric titrations in 0,1 M KNO3. These measurements revealed the formation of di- and trileptic complexes in the presence of an excess of ligand. The chemical model includes five species of [Fem(L)lHh](3–2l+h)+ general formula : [Fe(L)]+, [Fe(L)(OH)], [Fe(L)(OH)2]–, [Fe(L)2H] and [Fe2(L)3]. The numerical treatment of the spectrophotometric data collected in the visible range, led us to propose the electronic absorption spectrum for each of the identified species. Moreover, electrospray ionization mass spectroscopy (ESI-MS) confirmed the formation of the mono- ([FeL]+) and dileptic ([FeL2H]) complexes. The potentiometric study of the abiotic dihydroxamic ligand (LCyPr)2– in the presence of seven trivalent lanthanides allowed us to propose a chemical model which includs five mono- and dileptic species ([Ln(LCyPr)]+, [Ln(LCyPr)H]2+, [Ln(LCyPr)OH], [Ln(LCyPr)2]–, [Ln(LCyPr)2H]) in 0,1 M KNO3. Finally, potentiometric and spectrophotometric measurements for the UO22+/(LCyPr)2– system suggested the formation at equilibrium to five of uranium(VI) complexes between p[H] = 2 and 10. The model includes the mono- and dileptic [UO2(LCyPr)], [UO2(LCyPr)H]+, [UO2(LCyPr)OH]–, [UO2(LCyPr)2]2–, [UO2(LCyPr)2H]– complexes. The combination of both techniques allowed us to assess the speciation of this radionuclide in KNO3 medium and to propose a coordination scheme for each complex

Le procédé hydrométallurgique le plus utilisé pour extraire l'uranium VI des minerais phosphoriques met en jeu un mélange synergique de deux molécules extractantes : HDEHP et TOPO. Si les combinaisons synergiques sont connues dans le domaine de l'extraction liquide/liquide, les mécanismes qui pilotent la synergie d'extraction sont encore mal décrits. Une approche multi-échelle a été utilisée pour décrire ces mécanismes, combinant deux descriptions qui diffèrent par leur centre d'intérêt, respectivement l'ion pour l'approche moléculaire et les agrégats d'extractants pour l'approche supramoléculaire. Ces deux approches ont parallèlement été rationnalisées par des calculs de dynamique moléculaire. La description obtenue permet de rendre compte de la synergie via la structure des complexes et des agrégats formés pour différents ratios HDEHP/TOPO. De la même façon, des composés bifonctionnels, qui combinent deux fonctions extractantes au sein de la même molécule ont été étudiés et comparés au système HDEHP/TOPO pour identifier l'origine de l'augmentation des performances d'extraction et de sélectivité. / Uranium VI is commonly extracted from phosphoric ores by a well-known process exploiting the synergistic mixture of two extractant molecules : HDEHP and TOPO. In the field of liquid-liquid extraction, synergistic combinations are common but the mechanisms at the origin of the synergy are not well understood. A multi-scale approach has been used to describe these mechanisms, combining two different descriptions : the molecular scale focuses on the ion point of view, while the supramolecular scale focuses on extractants' aggregation. These two approaches have been rationalized by molecular dynamics computations. The results allow describing the synergy through the structure of the complexes and aggregates. With the same approach, some bifunctional compounds, combining the two extracting sites in one molecule, have been studied and compared to the HDEHP/TOPO system in order to identify the origin of their increased capacities in extraction and selectivity.

The text doesn't have an abstract / El texto no presenta resumen

Esta Dissertação analisa a elaboração e a repercussão da Convenção de 1817, assinada pelo governo inglês e português. Adicionando artigos ao Tratado de 1815, que proibiu o tráfico de escravos ao norte do Equador, o ajuste bilateral de 1817 previa o direito de visita recíproco da marinha de guerra de ambas as nações e a formação de tribunais mistos (comissões) para julgar os traficantes que ignorassem a determinação do Tratado de 1815. A partir da Convenção, este trabalho pretende reavaliar o papel dos embaixadores lusitanos diante do corpo diplomático britânico; compreender as decisões elaboradas por D. João em relação ao tráfico de escravos; e indicar algumas das linhas do debate político em torno do futuro da Monarquia portuguesa no final da década de 1810. / This study analyzes the arranging and the impact of the Convention of 1817, signed by the English and Portuguese governments. Adding articles to the Treaty of 1815, which forbade the slave trade north of the Equator, the bilateral arrangement of 1817 established the reciprocal Right of Search of warships and Mixed Courts (Commissions) in order to judge Slavers who had ignored the commitment of Treaty of 1815. From the time of the Convention, this work intends to reevaluate the deal between Portuguese ambassadors and British diplomacy; to better understand the decisions decreed by D. João in respects to the slave trade; and to point out some of the aspects of political debates concerning the future of the Portuguese Monarchy, during the sojourn of the Real Court in Rio de Janeiro at the end of the decade of 1810.

Made available in DSpace on 2016-01-26T18:55:39Z (GMT). No. of bitstreams: 1 Soraia.pdf: 476391 bytes, checksum: 291042d1569afa2b16dd7b6c72516724 (MD5) Previous issue date: 2013-10-18 / Chromium (Cr) is a relatively common element and occupies the 21st position in the index most commonly occurring elements in the earth´s crust, occurring in nature in various combinations with other substances, may be in the form of ions with valence 0 + 2, +3 or +6. The Cr +3 (III) is considered an essential element for human and animal metabolism in small quantities, inert and stable in the environment, while the +6 Cr (VI) is very unstable, toxic and carcinogenic to a wide variety of occupational and contaminant organisms and water and food. It is estimated that tens of thousands of people are exposed to chromium VI worldwide, leading to toxic effects by inducing free radicals by the reduction of chromium in the presence of cellular reductants and interaction between free radicals and membrane proteins and intracellular modifying the processes of absorption and secretion of various substances. Some live microorganisms, called probiotics, showed antioxidant activity and scavenging of free radicals, which can minimize or prevent the toxic effect of contaminants, for their beneficial effect on human and animal health. The term probiotic is of Greek origin and means "for life" being defined as "live microorganisms administered in adequate amounts, confer health benefits to the host", besides acting in the prevention of cancer in the modulation of allergic reactions in improving health and blood lipid levels. Thus, the aim of this study was to evaluate different doses of potassium dichromate, with or without probiotic on the parameters: nutritional performance and glycemic, lipid, renal and hepatic profiles in Wistar rats. / O crômio (Cr) é um elemento relativamente comum e ocupa a 21a posição no índice de elementos que ocorrem mais comumente na crosta terrestre, ocorrendo na natureza em várias combinações com outras substâncias, podendo apresentar-se na forma de íons com valência 0, +2, +3 ou +6. O Cr +3 (III) é considerado um elemento essencial para o metabolismo humano e animal em pequenas quantidades, inerte e não instável no ambiente, enquanto que o Cr +6 (VI) é muito instável, tóxico e carcinogênico para uma grande variedade de organismos e ocupacionalm e contaminante da água e alimentos. Estima-se que dezenas de milhares de pessoas estão expostas ao crômio VI em todo o mundo, provocando efeitos tóxicos através da indução de radicais livres pela redução do crômio, na presença de redutores celulares e a interação dos radicais livres com as proteínas da membrana e intracelulares, modificando os processos de reabsorção e secreção de diferentes substâncias. Alguns microorganismos vivos, denominados de probióticos, mostraram atividade antioxidante e captadora de radicais livres, o que pode minimizar ou impedir o efeito tóxico de contaminantes, pelo seu efeito benéfico sobre a saúde humana. O termo probiótico é de origem grega e significa "para a vida" sendo definidos como "microrganismos vivos, administrados em quantidades adequadas, que conferem benefícios a saúde do hospedeiro", além de atuar na prevenção de câncer, na modulação de reações alérgicas, na melhoria da saúde e nos níveis sanguíneos de lipídeos. Dessa forma, o objetivo do presente trabalho foi o de avaliar diferentes doses de dicromato de potássio, com ou sem probiótico, sobre os parâmetros: desempenho nutricional e perfis glicêmico, lipídico, renal e hepático em ratos Wistar.

Made available in DSpace on 2016-01-26T18:55:40Z (GMT). No. of bitstreams: 1 Reinaldo Camacho Bezerra.pdf: 607647 bytes, checksum: 1745657e41ebeb1e290325ce90721b08 (MD5) Previous issue date: 2014-03-21 / This work aims to evaluate the alterations, depending on the dose of potassium dichromate (0, 12, 24 and 36 mg.km-¹), in liver tissue after supplementation with probiotic at dosages 0 or 0.2% in 90 male rats. Oral ingestion done for 90 days of increasing amounts of potassium dichromate produced clinical signs of toxicity compared to histopathological analysis (p&#706;0.05), and seric enzymatic activities (p&#706;0.05), markers of hepatic function. The inclusion of probiotics to the diet reduced the effects on the studied parameters, indicating that it can be used to detoxify and/or prevent the action of the mineral, however other studies should be conducted to determine the most appropriate microorganisms and their dosages to minimize and/or to prevent the action of these xenobiotics in humans and animals. / O objetivo do presente trabalho foi o de avaliar as alterações dependentes da dose de dicromato de potássio (0, 12, 24 e 36 mg.kg-1) no tecido hepático, após suplementação com probiótico em dosagens 0 ou 0,2%, em 90 ratos machos. A ingestão oral por 90 dias de doses crescentes de dicromato de potássio produziu sinais clínicos de toxicidade frente a análise histopatológica (p<0,05) e atividades séricas enzimáticas (p<0,05), dos marcadores de função hepática. A inclusão do probiótico na dieta reduziu os efeitos nos parâmetros estudados, indicando que ele pode ser utilizado para desintoxicar e/ou impedir a ação desse mineral, porém outros estudos deverão ser realizados para determinar os microorganismos mais apropriados e suas dosagens, para minimizar e/ou impedir a ação desses xenobióticos nos homens e animais.

Made available in DSpace on 2016-07-18T17:53:12Z (GMT). No. of bitstreams: 1 Soraia.pdf: 476391 bytes, checksum: 291042d1569afa2b16dd7b6c72516724 (MD5) Previous issue date: 2013-10-18 / Chromium (Cr) is a relatively common element and occupies the 21st position in the index most commonly occurring elements in the earth´s crust, occurring in nature in various combinations with other substances, may be in the form of ions with valence 0 + 2, +3 or +6. The Cr +3 (III) is considered an essential element for human and animal metabolism in small quantities, inert and stable in the environment, while the +6 Cr (VI) is very unstable, toxic and carcinogenic to a wide variety of occupational and contaminant organisms and water and food. It is estimated that tens of thousands of people are exposed to chromium VI worldwide, leading to toxic effects by inducing free radicals by the reduction of chromium in the presence of cellular reductants and interaction between free radicals and membrane proteins and intracellular modifying the processes of absorption and secretion of various substances. Some live microorganisms, called probiotics, showed antioxidant activity and scavenging of free radicals, which can minimize or prevent the toxic effect of contaminants, for their beneficial effect on human and animal health. The term probiotic is of Greek origin and means "for life" being defined as "live microorganisms administered in adequate amounts, confer health benefits to the host", besides acting in the prevention of cancer in the modulation of allergic reactions in improving health and blood lipid levels. Thus, the aim of this study was to evaluate different doses of potassium dichromate, with or without probiotic on the parameters: nutritional performance and glycemic, lipid, renal and hepatic profiles in Wistar rats. / O crômio (Cr) é um elemento relativamente comum e ocupa a 21a posição no índice de elementos que ocorrem mais comumente na crosta terrestre, ocorrendo na natureza em várias combinações com outras substâncias, podendo apresentar-se na forma de íons com valência 0, +2, +3 ou +6. O Cr +3 (III) é considerado um elemento essencial para o metabolismo humano e animal em pequenas quantidades, inerte e não instável no ambiente, enquanto que o Cr +6 (VI) é muito instável, tóxico e carcinogênico para uma grande variedade de organismos e ocupacionalm e contaminante da água e alimentos. Estima-se que dezenas de milhares de pessoas estão expostas ao crômio VI em todo o mundo, provocando efeitos tóxicos através da indução de radicais livres pela redução do crômio, na presença de redutores celulares e a interação dos radicais livres com as proteínas da membrana e intracelulares, modificando os processos de reabsorção e secreção de diferentes substâncias. Alguns microorganismos vivos, denominados de probióticos, mostraram atividade antioxidante e captadora de radicais livres, o que pode minimizar ou impedir o efeito tóxico de contaminantes, pelo seu efeito benéfico sobre a saúde humana. O termo probiótico é de origem grega e significa "para a vida" sendo definidos como "microrganismos vivos, administrados em quantidades adequadas, que conferem benefícios a saúde do hospedeiro", além de atuar na prevenção de câncer, na modulação de reações alérgicas, na melhoria da saúde e nos níveis sanguíneos de lipídeos. Dessa forma, o objetivo do presente trabalho foi o de avaliar diferentes doses de dicromato de potássio, com ou sem probiótico, sobre os parâmetros: desempenho nutricional e perfis glicêmico, lipídico, renal e hepático em ratos Wistar.

Made available in DSpace on 2016-07-18T17:53:13Z (GMT). No. of bitstreams: 1 Reinaldo Camacho Bezerra.pdf: 607647 bytes, checksum: 1745657e41ebeb1e290325ce90721b08 (MD5) Previous issue date: 2014-03-21 / This work aims to evaluate the alterations, depending on the dose of potassium dichromate (0, 12, 24 and 36 mg.km-¹), in liver tissue after supplementation with probiotic at dosages 0 or 0.2% in 90 male rats. Oral ingestion done for 90 days of increasing amounts of potassium dichromate produced clinical signs of toxicity compared to histopathological analysis (p&#706;0.05), and seric enzymatic activities (p&#706;0.05), markers of hepatic function. The inclusion of probiotics to the diet reduced the effects on the studied parameters, indicating that it can be used to detoxify and/or prevent the action of the mineral, however other studies should be conducted to determine the most appropriate microorganisms and their dosages to minimize and/or to prevent the action of these xenobiotics in humans and animals. / O objetivo do presente trabalho foi o de avaliar as alterações dependentes da dose de dicromato de potássio (0, 12, 24 e 36 mg.kg-1) no tecido hepático, após suplementação com probiótico em dosagens 0 ou 0,2%, em 90 ratos machos. A ingestão oral por 90 dias de doses crescentes de dicromato de potássio produziu sinais clínicos de toxicidade frente a análise histopatológica (p<0,05) e atividades séricas enzimáticas (p<0,05), dos marcadores de função hepática. A inclusão do probiótico na dieta reduziu os efeitos nos parâmetros estudados, indicando que ele pode ser utilizado para desintoxicar e/ou impedir a ação desse mineral, porém outros estudos deverão ser realizados para determinar os microorganismos mais apropriados e suas dosagens, para minimizar e/ou impedir a ação desses xenobióticos nos homens e animais.