Made available in DSpace on 2016-04-28T20:18:31Z (GMT). No. of bitstreams: 1 2008 - Carlos Otavio Jordao Moreira da Rocha.pdf: 1867760 bytes, checksum: 3392639adc640e871d82c97af23d8da8 (MD5) Previous issue date: 2008-08-29 / With the objective of testing the resistance and the biomechanical behavior of external fixators of low cost used in veterinary medicine, were created 6 prototypes la type manufactured from alternative materials, using as orthopedic implants, stainless steel screws 304 porous, and as stabilized bar the methacrylate resin or wood poles (Pinnus ellioti). The models of the fixators tested differ because they have 2, 3 or 4 implants per fractured segment. With the purpose of doing biomechanical evaluations that are closer to the real clinical situation, were selected 2 tubes of polyvinylchloride, commercially known as PVC, with 10 cm length, internal diameter of 1,27 cm and external diameter of 1,95, far 5 cm from each other, representing, this way, the bone bands and the focus of an unstable fracture. This kind of tube is like a long bone because it has an internal space that represents the medullar area and external walls that represent the two osseous cortical. To each external fixator model, were created 5 prototypes, which were submitted to mechanic tests to evaluate the axial compression strength. The device to evaluate the prototypes was the Instron model 4204, with a charge cell of 5 KN (Kilogram-Newton) and the speed of the axial compression was 2 cm/minute, according the rules ASTM D695-92. The values of rigidity, drainage point and maximum security charge were calculated, according to the methodology used by Willer et al., (1991) and by Falc?o (2004). The mechanical evaluation was done in the Instituto de Macromol?culas Elo?sa Mano in the Universidade Federal do Rio de Janeiro. We concluded that the models with the stabilized bar made of resin required a larger load than the models made of wood to suffer a plastic deformation. The model with 3 screws per segment of PVC tube and a resin stabilized bar showed to tolerate a higher weight than the others, before showing a plastic deformation, this way it s indicated to dogs that weight up to 26,5Kg with fractures in the thoracic limbs and for dogs that weight up to 44Kg that have fractures in the pelvic limbs. / Com objetivo de testar a resist?ncia e o comportamento biomec?nico de fixadores externos de baixo custo utilizados em medicina veterin?ria, foram criados 6 modelos de prot?tipos do tipo Ia confeccionados a partir de materiais alternativos, utilizando-se como implantes ortop?dicos parafusos de a?o inoxid?vel 304 porosos e totalmente rosqueados, e como barra estabilizadora a resina de metacrilato ou hastes de madeira (Pinnus ellioti). Os modelos dos fixadores testados ainda se diferenciam por apresentarem 2, 3 ou 4 implantes por segmento fraturado. Com a finalidade de realizar avalia??es biomec?nicas o mais pr?ximo poss?vel da situa??o cl?nica, optou-se pela escolha de 2 tubos de policloreto de vinila, comercialmente conhecido como PVC, apresentando 10 cm de comprimento, 1,27 cm de di?metro interno e 1,95 cm de di?metro externo, afastados 5 cm entre si, representando assim os fragmentos ?sseos e o foco de uma fratura inst?vel. Este tipo de tubo se assemelha a um osso longo por apresentar um espa?o interno que representa a ?rea medular enquanto que as paredes externas representam as duas corticais ?sseas. Para cada modelo de fixador externo foram criados 5 prot?tipos, submetidos a testes mec?nicos para avalia??o da for?a de compress?o axial. O aparelho para avalia??o dos prot?tipos foi o Instron modelo 4204, com c?lula de carga de 5 KN (Quilograma-Newton) e a velocidade da compress?o axial foi de 2 cm/minuto, seguindo as normas ASTM D695-91. Calculamos as cargas de rigidez, ponto de escoamento e carga de seguran?a m?xima. A avalia??o mec?nica foi realizada no Instituto de Macromol?culas Elo?sa Mano na Universidade Federal do Rio de Janeiro. Conclu?mos que os modelos com barra estabilizadora em resina necessitou de uma carga maior do que os modelos de madeira para sofrer deforma??o pl?stica. O modelo com 3 parafusos por segmento de tubo de PVC e barra estabilizadora de resina mostrou suportar maior peso que os demais, antes de apresentar uma deforma??o pl?stica, sendo indicado para c?es com peso corporal de at? 26,5 Kg portadores de fraturas nos membros tor?cicos e para c?es com peso de at? 44 Kg que apresentem fraturas nos membros p?lvicos.

Os aminoácidos de cadeia ramificada (ACR) são considerados indispensáveis, pois não podem ser sintetizados endogenamente, sendo facilmente obtidos pela dieta. Entretanto, em determinadas condições clínicas, tanto a ingestão quando a absorção desses aminoácidos pode estar comprometida, levando ao estado hipercatabólico e prejudicando a função imune. O papel imunomodulador dos ACR tem sido relacionado com a melhora no balanço nitrogenado e o aumento da síntese e proliferação de células imunes, bem como, da síntese de mediadores inflamatórios. Entretanto, o mecanismo pelo qual os ACR exercem essas funções supracitadas ainda não é claro na literatura científica. Desta forma, esse trabalho teve como objetivo avaliar os efeitos da suplementação com ACR sobre os parâmetros inflamatórios e moleculares em macrófagos RAW 264.7 estimulados com lipopolissacarídeo (LPS). As culturas celulares foram distribuídas em cinco grupos: CTL - sem suplementação com ACR; LEU - suplementado com leucina (2 mmol/L); ISO - suplementado com isoleucina (2mmol/L); VAL - suplementado com valina (2 mmol/L) e LIV - suplementado com leucina (2 mmol/L), isoleucina (2 mmol/L) e valina (2 mmol/L). O estado inflamatório foi induzido pela adição de LPS (1 µg/mL) ao meio de cultura, seguindo quatro protocolos de tratamento: PT - pré-tratamento; TA - tratamento agudo; TC - tratamento crônico e TT - tratamento tardio. O ensaio de viabilidade celular foi realizado pelo teste MTT e a dosagem de óxido nítrico (NO) pela reação de Griess. As citocinas pró e anti-inflamatórias, e a prostaglandina E2 (PGE2) foram analisadas pelo método de ELISA. Para a avaliação dos parâmetros moleculares foi utilizado o método de western blotting. Houve aumento da viabilidade celular em todos os grupos suplementados em relação ao grupo controle no TA, no TC e no TT. Acerca da síntese de NO, a suplementação com ACR foi capaz de aumentar esse parâmetro em três dos quatro tratamentos propostos (PT, TA e TC). Em relação à síntese de citocinas pró e anti-inflamatórias, o PT e o TC foram mais eficazes em aumentar esse parâmetro em comparação aos outros tratamentos. Não houve diferença entre os grupos em relação à capacidade de síntese de PGE2 e à fosforilação de proteínas intracelulares. A partir dos resultados obtidos é possível concluir que os ACR contribuem significativamente para a viabilidade celular, bem como para a síntese de mediadores pró e anti-inflamatórios, sendo que o protocolo de suplementação se apresenta como fator determinante para obtenção desses resultados. Apesar da literatura científica atribuir grande parte dos efeitos imunomodulatórios à leucina, os resultados obtidos nesse estudo atribuem relevante potencial imunomodulador à isoleucina, abrindo espaço para um importante tema de estudo. / Branched chain amino acids (BCAA) are considered indispensable, since they cannot be endogenously synthesized, being easily obtained by diet. However, in certain clinical conditions, both the intake and absorption of these amino acids may be compromised, leading to the hypercatabolic state and impairing the immune function. The immunomodulatory role of BCAA has been associated with the nitrogen balance improvement and the increase of production and proliferation of immune cells, as well as the synthesis of inflammatory mediators. However, the mechanisms by which BCAA modulate the immune system have not yet been completely elucidated. In this sense, this study aimed to evaluate the effects of BCAA supplementation on intracellular mechanisms and inflammatory parameters in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. Cell cultures were distributed into five groups: CTL - without ACR supplementation; LEU - supplemented with leucine (2 mmol/L); ISO - supplemented with isoleucine (2mmol / L); VAL - supplemented with valine (2 mmol/L) and LIV - supplemented with leucine (2 mmol/L), isoleucine (2 mmol/L) and valine (2 mmol/L). The inflammatory state was induced by the addition of LPS (1 µg/ml) to the culture medium, following four treatment protocols: PT - pre-treatment; TA - acute treatment; TC - chronic treatment and TT - late treatment. The cell viability assay was performed by the MTT test and the nitric oxide (NO) dosage by the Griess reaction. Pro- and anti-inflammatory cytokines, and prostaglandin E2 (PGE2) were analyzed by ELISA. For the evaluation of the molecular parameters, the western blotting method was used. There was an increase in cell viability in all supplemented groups in relation to the control group in the TA, TC and TT treatments. Regarding NO synthesis, BCAA supplementation was able to increase NO production in three of the four proposed treatments (PT, TA and TC). In relation to the production of pro- and anti-inflammatory cytokines, PT and CT were more effective in increasing this parameter, compared to the other treatments. There was no difference between groups in relation to PGE2 production and intracellular protein phosphorylation. From the obtained results it is possible to conclude that the BCAA significantly contributed to the cell viability, as well as, for the production of pro and anti-inflammatory mediators, and the supplementation protocol presents as determinant factor to obtain these results. Although the scientific literature attributed a large part of the immunomodulatory effects to leucine, the results obtained in this study attribute relevant immunomodulatory potential to isoleucine, opening space for an important study topic.

Class of 2012 Abstract / Specific Aims: To evaluate the presence of statistical information from clinical studies in official product labeling specific for disease-modifying anti-rheumatic drugs (DMARDs) used in the treatment of rheumatoid arthritis. Methods: Data were abstracted from official product labeling DMARDs with FDA approval for treatment of rheumatoid arthritis. Each document was examined for the presence of statement regarding a priori type 1 error rate, p-values, and measures of variance. Medications were classified as either biologic or non-biologic. Main Results: A total of 14 DMARDs, 7 biologics (50%) and 7 non-biologics (50%), were found to be FDA approved for the treatment of rheumatoid arthritis. Primary outcomes consisted of American College of Rheumatology (ACR) response rates, radiographic changes, and health assessment questionnaire score (HAQ). Any measure of variance and the presence of a p-value were both found in six (43%) of the drug labels. Inclusion of p-values was found to be significantly greater in biologics compared to non-biologics for both ACR and radiographic results. Inclusion of variance was found to be significantly greater in biologics compared to non-biologics for radiographic changes only. No package inserts contained statements regarding the a priori type I error rate. Conclusions: Measures of variance are not frequently included in product labeling for either biologic or non-biologic DMARDs. However, inclusion of variance and p-values for ACR response rates and radiographic changes were more likely to be reported for biologics therapies as compared to non-biologics. A statement regarding Type 1 error rates were absent from labels regardless of outcome assessed.

Recent advances with the bacterial CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) defense system as genome editing tools have opened a new avenue for targeting disease-causing mutations. The programmability of the Cas9 endonuclease by RNA makes it a potentially powerful therapeutic tool to correct such mutations. The CRISPR-Cas9 system consists of a Cas9 endonuclease that is guided by RNA (sgRNA) to create double-stranded breaks in a target DNA segment complementary to the guide. This process is dependent on a 2-8 nucleotide sequence (called PAM) that is adjacent to the target and functions as a Cas9 binding signal. Each Cas9 ortholog recognizes a unique PAM. However, factors such as the size of Cas9 or the frequency of its PAM sequence in the genome have hindered its clinical use. The Cas9 from Streptococcus pyogenes (SpyCas9) is commonly used in research because its PAM (NGG, where “N” symbolizes any nucleotide) is present every ~8 bp in the genome, providing robust targeting potential. However, it is too large to fit into typical viral vectors used for in vivo delivery, namely adeno-associated vectors (AAV). While several Cas9 orthologs have been characterized, none satisfied the need for a compact, accurate Cas9 with a short PAM. In this thesis, we use two approaches to identify new compact Cas9 orthologs with small PAMs, one using anti-CRISPR proteins and one by searching through closely related Cas9s. First, we use the presence of anti-CRISPRs (naturally occurring, phage-encoded peptides that inhibit CRISPR-Cas9 described in chapter 2) in a genome as indicators of Cas9s that may be highly active. These orthologs come with the added advantage of having inhibitors that can be used as off-switches. We characterize four Cas9s that are targeted by anti-CRISPR proteins and show that they recognize diverse PAMs in vitro. One of the four Cas9’s, namely HpaCas9 from Haemophilus parainfluenzae, induces efficient genome editing in mammalian cells. However, its long N4GATTT PAM does not satisfy the short PAM criterion. For our second approach, we asked whether closely related Cas9 orthologs with drastically different PAM-interacting domains (PIDs, the domain responsible for PAM recognition) recognize different PAMs, and if so, can be used for genome editing. To this end, we exploited natural variation in the PID of closely related Cas9s to identify a compact ortholog from Neisseria meningitidis (Nme2Cas9). Nme2Cas9 recognizes a simple dinucleotide PAM (N4CC) that provides a high target site density. All-in-one AAV delivery of Nme2Cas9 with a guide RNA into adult mouse liver produces efficient genome editing and reduced serum cholesterol with exceptionally high specificity. We further expand our single-AAV platform to pre-implanted zygotes for streamlined generation of genome-edited mice. Finally, we show preliminary data on how CRISPR-Cas9 can be used for therapeutic genome editing for Amytrophic Lateral Sclerosis. Our new findings promise to accelerate the development of genome editing tools for biomedical and therapeutic applications.

Made available in DSpace on 2014-12-17T15:41:41Z (GMT). No. of bitstreams: 1 GuymmannCS.pdf: 1754712 bytes, checksum: 731ccc6c9bb4f783f3a118094959297b (MD5) Previous issue date: 2008-02-29 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Latices based on acrylic acid and ethyl methacrylate, crosslinked with 1,6‐propoxylate‐hexanodiol diacrylate were synthesized via emulsion polymerization with different monomeric compositions. The resultant latices were thickened with different NaOH/(acrylic acid) molar ratios and were characterized by titrimetry, zeta potential measurements, turbidimetry, and capillary viscometry. Intrinsic viscosity was determined for an uncrosslinked copolymer, using toluene as solvent. All the latices were coagulated with NaCl and washed with water at 60?C analyzed by FTIR spectrophotometry, in order to characterize functional groups from the copolymer and crosslinking agent. / L?tices ? base de ?cido acr?lico e metacrilato de etila, reticulados com 1,6‐diacrilato de propoxilato hexanodiol, foram sintetizados via polimeriza??o em emuls?o, com diferentes composi??es monom?ricas. Os l?tices sintetizados foram espessados com diferentes raz?es molares NaOH/(?cido acr?lico) e caracterizados por titrimetria, medidas de potencial zeta, turbidimetria e viscometria capilar. Todos os l?tices foram coagulados com NaCl, lavados com ?gua destilada e em seguida secos a 60 0C, para a an?lise de FTIR. A viscosidade intr?nseca do l?tex n?o reticulado foi determinada utilizando tolueno como solvente. O potencial zeta foi usado para determinar a carga superficial das part?culas e o FTIR para caracterizar os grupos funcionais dos comon?meros.

Made available in DSpace on 2014-12-17T15:41:43Z (GMT). No. of bitstreams: 1 ZilvanMS.pdf: 850138 bytes, checksum: 377846a49fcf47805db83b68c5e1b5f7 (MD5) Previous issue date: 2007-07-31 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Latexes based on acrylic acid, acrylamide, ethyl methacrylate, and ethyl acrylate were synthesized via emulsion polymerization with different monomer compositions. The resultant latices were thickened with different molar ratios of NaOH to acrylic acid and were analyzed in terms of acid‐basis titrimetry, turbidimetry, rheology, and tensiometry. Titrimetry, turbidimetry, and rheometry were used to analyze factors such as carboxyl group availability and particle solubilization, tensiometry monitoring the influence of carboxyl neutralization on polymer‐surfactant interactions. For the acrylic acid content used in this work (20 wt%), the results indicated that as carboxyl groups distribution became more homogeneous, the process of latex thickening became more effective / L?tices baseados em ?cido acr?lico, acrilamida, acrilato de etila e metacrilato de etila foram sintetizados via polimeriza??o em emuls?o com diferentes composi??es monom?ricas. Os l?tices resultantes foram espessados a diferentes raz?es molares de NaOH/?cido acr?lico. Titrimetria ?cido‐base, turbidimetria, reometria e tensiometria foram usados para analisar fatores tais como a disponibilidade de grupos carboxila e a solubiliza??o de part?culas, a tensiometria sendo usada para monitorar a influ?ncia da neutraliza??o de grupos carboxilas nas intera??es pol?mero‐surfactante. Para o teor de ?cido acr?lico usado neste trabalho (20 m/m%), os resultados indicaram que, a medida em que a distribui??o de grupos carboxilas torna‐se mais homog?nea, o processo de espessamento tornou‐se mais efetivo

Made available in DSpace on 2014-12-17T15:41:55Z (GMT). No. of bitstreams: 1 JessicaEAF_DISSERT.pdf: 2802549 bytes, checksum: f4835fb277277d60879f0b91ee07c465 (MD5) Previous issue date: 2011-02-28 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / In this work, the plant species Copernicia prunifera (Miller) H. E. Moore (carnauba), naturally occurring which prevails in the northeast region of Brazil was the subject of studies aiming its use as external coating of pipelines used in petroleum industry. The part of the plant worked were the leaves, also called straw, which were coated with resinous material. For this purpose, it was necessary to evaluate the effectiveness of the use of acrylic resins in the straw carnauba coating. The properties of the untreated carnauba straw and chemically treated with sodium hydroxide, hexane and carbon tetrachloride were investigated by ATRFTIR, SEM and thermal analysis. The first two techniques showed that treatment with solvents has caused major changes in the straw surface, while the thermal analysis indicated that the sodium hydroxide caused variations in thermal stability of straw constituents. Water absorption measurements showed that treatments have accelerated the absorption process and the reduction of contact angle values for treated samples with solvents indicated higher hidrophilicity of straw. The tensile tests showed lower values of elastic modulus and tensile strength for treated samples. Furthermore, coatings using pure commercial resins A and B as well as the formulations with clay were applied in straw and they were examined once again through thermal analysis, water absorption measurements, contact angle and mechanical tests. To analyze the effect of heat ageing, samples were subjected to tensile tests again in order to assess its resistance. The results showed that the resins/clay formulations increased thermal stability of straw, they promoted a good impermeabilization and caused significant decrease in the values of elastic modulus and tensile strength. Evaluating the ageing effect on the mechanical properties, it has been showed good recovery to the coated straw with the formulations A 60 and A 80% in modulus and tensile strength values and elongation at break values have remained very close. It is thus concluded that the carnauba straw can be used as a coating of pipelines with significant cost savings, since there is no need for pretreatment for its use and shows itself as a viable biotechnology alternative, contributing to the quality of coatings material and environment preservation. / Neste trabalho, a esp?cie vegetal Copernicia prunifera (Miller) H. E. Moore (carna?ba), de ocorr?ncia natural predominante da regi?o Nordeste do Brasil, foi alvo de estudos objetivando sua utiliza??o como revestimento externo de dutos da ind?stria do petr?leo. A parte da planta trabalhada foram as folhas, tamb?m chamadas de palhas, que receberam um revestimento resinoso. Para tanto, foi necess?rio avaliar a efic?cia do uso de resinas acr?licas no revestimento da palha de carna?ba. As propriedades da palha n?o-tratada e tratada quimicamente com hidr?xido de s?dio, hexano e tetracloreto de carbono foram investigadas por FTIR-ATR, MEV e TG. As duas primeiras t?cnicas mostraram que os tratamentos com os solventes provocaram maiores modifica??es na superf?cie da palha, enquanto o estudo termogravim?trico indicou que o hidr?xido de s?dio causou varia??es na estabilidade t?rmica dos constituintes da palha. Medidas de absor??o de ?gua mostraram que os tratamentos aceleraram o processo de absor??o e a redu??o dos valores de ?ngulo de contato para as amostras tratadas com os solventes indicou aumento da hidrofilicidade das palhas. Os ensaios mec?nicos apresentaram menores valores de m?dulo el?stico e tens?o de ruptura para as amostras tratadas. Al?m disso, revestimentos com resinas comerciais puras A e B assim como composi??es com argila foram aplicados nas palhas e estas foram analisadas novamente atrav?s da termogravimetria, medidas de absor??o de ?gua, ?ngulo de contato e resist?ncia mec?nica. Para analisar o efeito do envelhecimento t?rmico realizado, as amostras foram submetidas mais uma vez aos ensaios mec?nicos, a fim de avaliar sua resist?ncia. Os resultados mostraram que as formula??es resinas/argila aumentaram a estabilidade t?rmica da palha, promoveram uma boa impermeabiliza??o e causaram significativa redu??o nos valores de m?dulo el?stico e tens?o de ruptura. Ao avaliar o efeito do envelhecimento nas propriedades mec?nicas, percebeu-se boa recupera??o nos valores de m?dulo e tens?o para a palha revestida com as formula??es A 60 e A 80%. J? os resultados de deforma??o mostraram que os valores permaneceram bem pr?ximos. Dessa forma, conclui-se que a palha de carna?ba pode vir a ser utilizada como revestimento de dutos com significante redu??o de custos, j? que n?o h? a necessidade de tratamento pr?vio para seu uso e mostra-se como uma alternativa biotecnol?gica vi?vel, contribuindo com a qualidade de material de revestimentos e a preserva??o do meio ambiente.

Made available in DSpace on 2014-12-17T15:42:27Z (GMT). No. of bitstreams: 1 MariaSPL.pdf: 2188057 bytes, checksum: 3142bea2af0c353bf960b7b878efd707 (MD5) Previous issue date: 2006-11-17 / The aim of this study was to generate an asymmetric biocompactible and biodegradable chitosan membrane modified by the contact with a poly(acrylic acid) solution at one of its sides at room temperature and 60◦C. The pure chitosan membrane, as well as the ones treated with poly(acrylic acid) were characterized by infrared spectroscopy (FTIRATR) at angles of 39◦, 45◦ and 60◦ , swelling capacity in water, thermal analysis (TG/DTG), scanning electronic microscopy (SEM) and permeation experiments using metronidazole at 0,1% and 0,2% as a model drug. The results confirmed the presence of ionic interaction between chitosan and poly(acrylic acid) by means of a polyelectrolyte complex (PEC) formation. They also showed that such interactions were more effective at 60◦C since this temperature is above the chitosan glass transition temperature wich makes the diffusion of poly(acrylic acid) easier, and that the two treated membranes were asymmetrics, more thermically stable and less permeable in relation to metronidazole than the pure chitosan membrane / O prop?sito deste estudo foi produzir uma membrana assim?trica biocompat?vel e biodegrad?vel de quitosana modificada pelo contato com uma solu??o de poli(?cido acr?lico) em uma de suas superf?cies ? temperatura ambiente e a 60◦C. As membranas de quitosana pura, quitosana com poli(?cido acr?lico) a 25◦C e quitosana com poli(?cido acr?lico) a 60◦C foram caracterizadas por: espectroscopia no infravermelho (FTIRATR) em ?ngulos de incid?ncia de 39◦, 45◦ e 60◦, ganho de massa em ?gua, an?lise t?rmica (TG/ DTG), microscopia eletr?nica de varredura (MEV) e, ainda, atrav?s dos ensaios de permea??o in vitro utilizando como f?rmaco modelo o metronidazol em solu??o aquosa nas concentra??es de 0,1 e 0,2%. Os resultados obtidos comprovaram a exist?ncia de intera??es i?nicas entre os dois pol?meros, atrav?s da forma??o dos chamados complexos polieletrol?ticos. Tamb?m mostraram que a reticula??o foi mais efetiva a 60◦C , uma vez que essa temperatura est? acima da temperatura de transi??o v?trea da quitosana, o que facilita a difus?o do poli(?cido acr?lico) e que as membranas resultantes s?o assim?tricas, mais est?veis termicamente e menos perme?veis ao metronidazol do que a membrana de quitosana pura

Dans cette thèse, nous étudions l'effet de la répartition inégale des ressources naturelles entre les pays sur trois aspects principaux. Dans le premier chapitre, nous examinons empiriquement les effets asymétriques potentiels de l'adhésion à l'Organisation Mondiale du Commerce (OMC) entre les membres, en nous concentrant spécifiquement sur les pays en développement. Les résultats suggèrent que l'adhésion à l'OMC a contribué à l'augmentation des exportations de tous les pays, à l'exception des pays non-émergents riches en ressources. En revanche, les pays émergents riches en ressources sont les plus grands bénéficiaires de l'accession à l'OMC. Dans le deuxième chapitre, nous explorons empiriquement l'impact de la dotation en ressources naturelles sur les gains de six Accords Commerciaux Régionaux (ACR) entre les membres à travers trois axes : la complémentarité entre les pays, la diversification des pays riches en ressources ainsi que la création et le détournement des échanges. Nous concluons que la complémentarité entre les pays riches et les pays pauvres en ressources a été atteinte dans les accords de l’ECOWAS, du SADC et du CIS. Les résultats indiquent également que, dans tous les ACR, les pays riches en ressources ont accru leurs exportations hors secteurs des ressources naturelles et diversifié ainsi leurs structures d'exportation, en particulier avec les partenaires régionaux. En outre, dans la plupart des ACR, les pays pauvres ont accru leurs exportations vers leurs partenaires riches en ressources, tandis que ces derniers souffrent du détournement des échanges en termes d'importations. Dans le dernier chapitre, nous étudions l'impact de la dotation en ressources naturelles sur le processus de convergence entre les pays du PAFTA. Premièrement, les résultats démontrent que la sigma-convergence n'était observable qu'entre 1970 et 1990 dans les pays du PAFTA. De plus, l’estimation révèle que les ressources naturelles sont l'un des principaux déterminants de la convergence conditionnelle au sein du PAFTA. Par conséquent, l'asymétrie entre les pays en termes de dotation en ressources naturelles n'a pas empêché la convergence dans le PAFTA. L'analyse de la convergence des clubs a identifié trois principaux clubs parmi les pays du PAFTA. En outre, les facteurs qui ont déterminé la formation des clubs sont les ressources naturelles, la qualité des institutions et l'investissement. Par ailleurs, une abondance de ressources naturelles n'est pas suffisante pour être le meilleur club, mais doit être accompagnée d'institutions de qualité. / In this thesis, we examine the effect of the unequal distribution of natural resources between countries on three main aspects. In chapter one, we empirically examine potential asymmetric effects of the accession of the World Trade Organization (WTO) across members, focusing specifically on the developing countries. The results suggest that membership in the WTO contributed to greater exports for all countries, except for non-emerging resource-rich countries. In contrast, emerging resource-rich countries are the greatest beneficiaries from the accession of the WTO. In chapter two, we empirically explore the impact of natural resource endowments on the gains of six Regional Trade Agreements (RTA) across members through three axes: complementarity between countries, diversification of resource-rich countries, and trade creation and diversion. We conclude that the complementarity between resource-rich and resource-poor countries has been achieved in the ECOWAS, SADC and CIS agreements. The results also indicate that in all RTAs, the resource-rich countries increased exports in non-natural resource sectors and thereby diversified their export structures, especially with regional partners. Moreover, in most RTAs, poor countries boosted their exports to resources-rich partners, while resource-rich countries suffer from trade diversion in terms of imports. In the last chapter, we study the impact of natural resource endowments on the process of convergence among PAFTA countries. First, the results demonstrate that sigma-convergence was only observable between 1970-1990 among PAFTA countries. The estimation reveals that natural resources are one of the main determinants of conditional convergence within PAFTA. Therefore, the asymmetry between countries in terms of natural resource endowment did not impede the convergence in PAFTA. Club convergence analysis identify three main clubs among PAFTA countries. In addition, the factors that determined clubs’ formation are natural resources, quality of institutions, and investment. Further, an abundance of natural resources is alone not enough to be the best club, but must be accompanied by high-quality institutions.

No description available.