Thesis (Ph.D. in Epidemiology) -- University of Colorado at Denver and Health Sciences Center, 2005. / Typescript. Includes bibliographical references (leaves 83-102).

The use of enzymes, nature´s own catalysts, both isolated or as whole cells to perform chemical transformations is called biocatalysis. As a complement to classical chemical catalysis, biocatalysis can be an environmentally friendly and more economical option in the production and synthesis of chemicals. Research on the application of amine transaminases in synthesis of chiral amines have exploded over the last two decades and interest from the industry is increasing. Amine transaminases are promising catalysts due to their ability to perform reductive amination of ketones with excellent enantioselectivity. For a process to be efficient, high substrate specificity of the applied enzyme is an important factor. A variant of Chromobacterium violaceum amine transaminase that was obtained through rational design has an increased specific activity toward (S)-1-phenylethylamine and a set of 4´-substituted acetophenones. This result makes this variant a promising catalyst for the asymmetric synthesis of similar amines. Amine transaminase catalyzed asymmetric synthesis of amines generally suffers from unfavorable equilibrium. Two methods that include spontaneous tautomerization and biocatalytic amidation for equilibrium displacement have therefore been developed. Efficient assays and screening methods are demanded for the discovery and development of novel amine transaminases. For this purpose, a sensitive fluorescence-based assay that holds promise as a high-throughput screening method was developed. One of the major obstacles for application of enzymes in industrial processes is the instability of the enzyme toward harsh conditions. The stability of Chromobacterium violaceum amine transaminase was investigated and improved using co-solvents and other additives. Co-lyophilization with surfactants was also applied to improve the performance of the same enzyme in organic solvents. / <p>QC 20161017</p>

No description available.

No description available.

Hepatite C tem evolução progressiva, persiste na maioria dos pacientes (85%) e leva a uma doença crônica assintomática.A maioria dos pacientes apresenta nível de ALT elevada e aproximadamente 25% normal. Estes geralmente são mulheres e não há associação entre genótipo e severidade da lesão hepática. Histologicamente apresentam lesão mínima e leve fibrose, embora cirrose tenha sido relatado.Visando estimar a prevalência, características demográficas, genotípicas e anatomopatológicas em pacientes com ALT normal, realizamos um estudo de série de 68 casos entre janeiro de 1997 a abril de 2000. A prevalência foi de 13,82%, 45,6% do gênero masculino e 54,4% feminino, média de idade 38 +/- 13 anos. Genótipo 1 em 84,75%, 2 em 6,78% e o 3 em 8,47%. Em 52,9% dos casos biópsia hepática revelou fígado reacional, porém uma importante proporção (29%) dos nossos pacientes com transaminases normais mostrou sinais de fibrose. Estes resultados sugerem a necessidade de revisar os algoritimos da prática de biópsia hepática nessa população / Hepatitis C evolves progressively persisting in the majority of patients (85%) resulting in na asymptomatic chronic disease.Most patients have high ALT levels and approximately 25% normal ALT.The latter are usually female and there is no association between genotype and severity hepatic lesion.Histology shows small lesion and low amount of fibrosis, despite cirrhosis having been reported.Aiming at assessing prevalence, demographic, genotypical and anatomopathological characteristics in patients with normal ALT levels, we studied a series of 68 cases between January 1997 and April 2000.There was a prevalence of 13,82%, 45,6% of which were male and 54,4% female, average age of 38+/-13 years.Genotype 1 in 84,75%, 2 in 6,78% and 3 in 8,47%.In 52,9% of the cases revealed liver reaction, however, an important proportion of patients showed histologic signs of fibrosis (29%).Theses results suggest the need to revisit the algorithm for liver biopsy practice

Hepatite C tem evolução progressiva, persiste na maioria dos pacientes (85%) e leva a uma doença crônica assintomática.A maioria dos pacientes apresenta nível de ALT elevada e aproximadamente 25% normal. Estes geralmente são mulheres e não há associação entre genótipo e severidade da lesão hepática. Histologicamente apresentam lesão mínima e leve fibrose, embora cirrose tenha sido relatado.Visando estimar a prevalência, características demográficas, genotípicas e anatomopatológicas em pacientes com ALT normal, realizamos um estudo de série de 68 casos entre janeiro de 1997 a abril de 2000. A prevalência foi de 13,82%, 45,6% do gênero masculino e 54,4% feminino, média de idade 38 +/- 13 anos. Genótipo 1 em 84,75%, 2 em 6,78% e o 3 em 8,47%. Em 52,9% dos casos biópsia hepática revelou fígado reacional, porém uma importante proporção (29%) dos nossos pacientes com transaminases normais mostrou sinais de fibrose. Estes resultados sugerem a necessidade de revisar os algoritimos da prática de biópsia hepática nessa população / Hepatitis C evolves progressively persisting in the majority of patients (85%) resulting in na asymptomatic chronic disease.Most patients have high ALT levels and approximately 25% normal ALT.The latter are usually female and there is no association between genotype and severity hepatic lesion.Histology shows small lesion and low amount of fibrosis, despite cirrhosis having been reported.Aiming at assessing prevalence, demographic, genotypical and anatomopathological characteristics in patients with normal ALT levels, we studied a series of 68 cases between January 1997 and April 2000.There was a prevalence of 13,82%, 45,6% of which were male and 54,4% female, average age of 38+/-13 years.Genotype 1 in 84,75%, 2 in 6,78% and 3 in 8,47%.In 52,9% of the cases revealed liver reaction, however, an important proportion of patients showed histologic signs of fibrosis (29%).Theses results suggest the need to revisit the algorithm for liver biopsy practice

Made available in DSpace on 2016-12-23T13:53:40Z (GMT). No. of bitstreams: 1 Cesar Otaviano Penna Junior.pdf: 505984 bytes, checksum: cd67e240dbaac144ea465c0209566a1b (MD5) Previous issue date: 2010-08-30 / The cross-breeding derived from specialized milk producing European breeds with zebu breeds that are adapted to tropical conditions form the basis of the majority of Brazil s milk producing systems. However, researches regarding the metabolic profile (MP) for bovine dairy cows focus on pure breeds coming mostly from temperate to subtropical regions. Therefore, the behaviour of the hematobiochemical components indicators on the energy metabolism in second calving rate order ½ and ¾ Holstein x Gir (HG) dairy cows, in two stages of lactation, became the object of the evaluation, as well as to determine its relationship with body condition (BCS) and milk production during the dry season in tropical environment. The experiment was conducted at Santa Luzia Farm, located in Minas Gerais - Brazil. This study used data collected in the months of May and August 2009 from 37 ½ HG cows and 35 ¾ HG cows. By our definition studies were focused on two lactation periods, the first being from 28 to 60 days (P1 lactation) and the second from 110 to130 days (P2 of lactation). The cows received complete feed in the trough. The biochemical indicators of the metabolic energy profile were analyzed through the beta-hydroxybutyrate (βHB), cholesterol and the enzyme Aspartate transaminase (AST) quantifications. The metabolite average values, with their standard errors, analyzed by Student test, were established for both blood degrees, in their respective lactation periods. Given the scarcity of information on reference values for the genetic group investigated in this study, reference values were methodically sought from studies using larger number of variables equal to the present study. There were statistical differences between the periods for βHB, milk production and BCS, whereas the other parameters did not differ for cows ½ and ¾ HG. There were statistical differences between the periods in βHB, milk production and BCS, whereas the other parameters did not differ for ½ and ¾ HG cows. Between blood degrees, the statistical differences occurred within each period concerning the βHB and milk production parameters and no other differences occurred in relation to the remaining parameters. Having obtained the results and taking the conditions to which the animals were exposed in this study into consideration, we have concluded that the genetic groups were effective in sustaining their respective levels of milk production without experiencing complications of metabolic order. We suggest such studies to be continuated as to equate Reference Values / Os cruzamentos derivados de raças européias especializadas para produção de leite com raças zebuínas adaptadas às condições tropicais formam a base da maioria dos sistemas de produção de leite no Brasil. Porém, verifica-se que os estudos a respeito de perfil metabólico (PM) para vacas bovinas leiteiras se concentram em raças puras, em sua grande maioria em regiões de clima temperado ou subtropical. Assim, com a revisão objetivou-se destacar a importância do uso do Perfil Metabólico energético na avaliação do desempenho produtivo de vacas leiteiras, seja no quesito nutricional, seja nas questões relacionadas ao diagnóstico e prevenção de transtornos de ordem metabólica nutricional e com a pesquisa aferir os valores e avaliar o comportamento dos marcadores bioquímicos energéticos entre dois períodos da lactação e entre diferentes graus genéticos de vacas HG de 2ª OP, no período da seca, em região tropical. O experimento foi realizado na Fazenda Santa Luzia, localizada no Estado de Minas Gerais Brasil. Foram utilizados dados coletados nos meses de maio e agosto de 2009, provenientes de 37 vacas ½ HG e 35 vacas ¾ HG. Definiu-se concentrar os estudos em dois períodos da lactação, sendo o primeiro de 28 a 60 dias (P1 da lactação) e o segundo de 110 a 130 dias (P2 da lactação). As vacas receberam ração total. Foram analisados os indicadores bioquímicos do perfil metabólico energético por meio da quantificação do Beta-hidroxibutirato (βHB), do colesterol e da enzima Aspartato transaminase (AST). Os valores médios dos metabólitos, com seus erros-padrão, analisados pelo teste t de Student, foram estabelecidos para ambos os graus de sangue, nos respectivos períodos da lactação. Dada a escassez de informações sobre valores referenciais para o grupo genético investigado nesse estudo, metodologicamente buscaram-se valores referenciais de estudos que utilizaram o maior número de variáveis iguais ao do presente trabalho. Ocorreram diferenças estatísticas (p<0,05) entre períodos para βHB, produção de leite e ECC, enquanto que os demais parâmetros não apresentaram diferenças (p>0,05) para vacas ½ e ¾ HG. Entre graus de sangue, as diferenças estatísticas (p<0,05) ocorreram dentro de cada período para os parâmetros βHB e produção de leite, não tendo ocorrido diferenças (p>0,05) para os demais parâmetros. Aferidos os valores, conclui-se que para as condições a que foram submetidos os animais no presente estudo, os grupos genéticos foram eficientes para sustentarem seus respectivos níveis de produção de leite, sem apresentarem complicações de ordem metabólica. Sugere-se a continuidade de estudos dessa natureza para equacionar Valores de Referência

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Biokatalys medför ett alternativt tillvägagångsätt för att kunna utforska och utveckla kemiskt syntetiserade vägar för produktionen av eftertraktade kemikalier, där hållbarhet och miljön tas till beaktan. I denna studie undersöktes potentialen av en enzymatisk kaskad för produktion av 5-hydroximetylfurfurylamin (HMFA). HMFA är en förening med tillämpningar inom flera industrier som till exempel jordbruks- och läkemedelsindustrin. Den enzymatiska kaskaden består av två reaktioner, varav den första involverar dekarboxylering av lysin med användning av lysindekarboxylas för att producera en så kallad ”smart amindonator” kadaverin. Den andra reaktionen i kaskaden består utav ett transaminas från Silicibacter pomeroyi (SpTA) som konverterarar 5-hydroximetylfurfuryl (HMF) till HMFA med hjälp av det framkallade kadaverinet från den första reaktionen i kaskaden. En enzymatisk kaskad tillåter mildare reaktionsbetingelser, mindre avfall och energisnål användning som därmed minskar miljöpåverkan samtidigt som det beaktar några av dem 12 principerna av grön kemi. Det uppstod utmaningar som hindrade slutförandet av den enzymatiska kaskaden, men trots detta erhölls värdefulla insikter. Denna studie belyser de invecklade reaktionsmekanismerna och några av de svårigheterna med immobilisering av enzym på EziG bärare. Trots att den avsedda kaskaden inte slutfördes, gav lärdomarna nya perspektiv samt potentiella områden att fortsätta undersöka för framtida framsteg inom biokatalys. / Biocatalysis is a promising alternative to chemical synthesis routes for high value chemicals which considers the sustainability and environmental aspect. In this study the feasibility of utilizing an enzymatic cascade for the production of 5-hydroxymethylfurfurylamine (HMFA) was explored. HMFA is a compound with diverse applications in industries such as agriculture and pharmaceuticals. The cascade consists of two main reactions, the first of which involves the decarboxylation of lysine using a lysine decarboxylase to produce cadaverine. The cadaverine produced will then be utilized as an amine donor in the second reaction, which involves the use of a transaminase derived from Silicibacter pomeroyi (SpTA) together with 5-hydroxymethylfurfural (HMF). This cascade considers the principals of green chemistry such as milder reaction conditions and less waste, hence aiming to reduce the environmental impact. Although there were challenges preventing the completion of the enzymatic cascade, valuable insights were gained. The contribution of this study sheds light on the intricate reaction mechanisms and some of the key difficulties with enzyme immobilisation. While the intended cascade was not finalized, the lessons learned will provide for new perspectives and potential future advancements in biocatalysis.