Made available in DSpace on 2016-08-12T18:48:50Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-11-11. Added 1 bitstream(s) on 2016-08-12T18:51:08Z : No. of bitstreams: 1 000864494.pdf: 1600996 bytes, checksum: 5adb69b16b5be76806071628d4796075 (MD5) / A deficiência de vitamina B12 no ser humano, frequentemente associada a deficiência de fator intrínseco, produzido no estômago, leva a múltiplas alterações neurológicas e hematológicas. A mais conhecida alteração do sistema nervoso central é a desmielinização e degeneração dos fascículos grácil e cuneiforme da medula cervical. Este trabalho teve por objetivo tentar obter um modelo experimental da afecção, através da gastrectomia total em ratos. Animais foram gastrectomizados, submetidos à suplementação polivitamínica via oral, e 2 a 3 meses depois submetidos a estudos de condução nervosa, com estímulos elétricos na extremidade da cauda, e captação de potenciais elétricos em 3 pontos, com distâncias iguais entre si: próximo ao ânus (potencial caudal), região inferior da coluna (potencial lombar) e região da protuberância cervical (potencial cortical). A velocidade de condução pela região inferior da medula espinhal foi denominada segmento V1, pela região torácica alta e cervical até o córtex, segmento V2. Após obtenções de registros de boa qualidade técnica em 15 gastrectomizados, os segmentos V1 e V2 foram comparados com dados de 20 controles pelo teste t de Student para amostras independentes, análise de variância (ANOVA) e teste de comparação múltipla de Tukey. Os animais gastrectomizados apresentaram reduções de velocidades estatisticamente significativas para o segmento V2. Os autores pensam ter conseguido modelo experimental da afecção em ratos, o que abre amplas perspectivas para testes terapêuticos em laboratório, com possibilidades para benefícios futuros ao homem / The B12 Vitamin deficiency in man, often associated with deficiency of intrinsic factor produced in the stomach, leading to several neurological and hematological disturbances. The best known alteration of the central nervous system is the demyelination and degeneration of the gracilis and cuneiform fascicles in the cervical spinal cord. This study aimed to try an experimental model of the disease, through total gastrectomy in rats. Animals were gastrectomized, submitted to oral polivitaminic supplementation, and 2-3 months later underwent nerve conduction studies. Electrical stimulation was done on the tail end, and electrical potentials were obtained at 3 points with equal distances from each other: near the anus (tail potential), lower spinal cord (lumbar potential) and the region of cervical spinal cord (cortical potential). The conduction velocity of the lower region of the spinal cord segment was named V1, the high spinal cord to the cortex was named V2 segment. After good quality records from 15 gastrectomized animals, the V1 and V2 segments were compared with data from 20 controls by the t Student test for independent samples, analysis of variance (ANOVA) and Tukey's multiple comparison test. Gastrectomized animals presented statistically significant reductions in the velocities for the V2 segment. The authors think they have obtained an experimental model of the disease in rats, which opens up broad prospects for therapeutic tests in the laboratory, with possibilities for future benefits to the man

CoordenaÃÃo de AperfeiÃoamento de NÃvel Superior / A infecÃÃo pelo Helicobacter pylori à uma das infecÃÃes mais prevalentes do mundo. Existem fortes evidÃncias de que a transmissÃo dessa bactÃria ocorre na infÃncia, e estudos epidemiolÃgicos em crianÃas sÃo essenciais para que se entenda os aspectos relacionados com a dinÃmica da infecÃÃo e suas conseqÃÃncias. Previamente pesquisadores vinculados ao LaboratÃrio de Gastroenterologia da Universidade Federal do Cearà avaliaram a prevalÃncia de H.pylori em crianÃas atà quatorze anos de idade em uma comunidade fixa de baixa renda, denominada Parque UniversitÃrio. No presente estudo, foi realizado outro corte transversal aproximadamente oito anos apÃs a anÃlise inicial nesse mesmo grupo de crianÃas, com o objetivo de avaliar a dinÃmica da infecÃÃo e se as crianÃas infectadas sÃo mais susceptÃveis a terem anemia, deficiÃncia de ferrritina, folato e vitamina B12 do que as nÃo infectadas. A infecÃÃo por H. pylori foi avaliada em 133 crianÃas por meio do teste respiratÃrio, previamente validado para a populaÃÃo brasileira. Foram coletadas amostras de sangue em 108 crianÃas para a realizaÃÃo de hemograma e a dosagem de concentraÃÃes sÃricas de ferritina, vitamina B12 e folato por meio da tÃcnica de quimioluminescencia utilizando Immulite  2000. A prevalÃncia da infecÃÃo por H. pylori nas crianÃas foi de 53,4% (71/133) em 2000, enquanto a prevalÃncia de H. pylori nas mesmas crianÃas em 2008 foi de 64,7% (86/133). ApÃs 8 anos, a maioria (88,7%) das crianÃas H. pylori positivas permaneceram infectadas. A taxa de aquisiÃÃo da infecÃÃo por H. pylori apÃs 8 anos da anÃlise inicial foi de 17,3% (23/133) e a taxa de cura espontÃnea da infecÃÃo foi de 6% (8/133). As taxas de aquisiÃÃo foram maiores em crianÃas com idade de 10 anos ou menos, atingindo 30,2% em crianÃas menores de 5 anos. A prevalÃncia da infecÃÃo em crianÃas com menos de 5 anos aumentou de 39.6% em 2000 para 62,2% em 2008 (p=0,020). NÃo houve diferenÃa estatisticamente significante entre anemia, concentraÃÃes sÃricas de ferritina, vitamina B12 e folato em indivÃduos H. pylori positivos comparados aos H. pylori negativos. Em conclusÃo, a infecÃÃo por H. pylori à adquirida precocemente na infÃncia, com altas taxas de aquisiÃÃo em crianÃas com 10 anos ou menos. NÃo foi encontrado associaÃÃo entre a infecÃÃo por H. pylori e anemia, nÃveis sÃricos de vitamina B12, ferritina e folato / A infecÃÃo pelo Helicobacter pylori à uma das infecÃÃes mais prevalentes do mundo. Existem fortes evidÃncias de que a transmissÃo dessa bactÃria ocorre na infÃncia, e estudos epidemiolÃgicos em crianÃas sÃo essenciais para que se entenda os aspectos relacionados com a dinÃmica da infecÃÃo e suas conseqÃÃncias. Previamente pesquisadores vinculados ao LaboratÃrio de Gastroenterologia da Universidade Federal do Cearà avaliaram a prevalÃncia de H.pylori em crianÃas atà quatorze anos de idade em uma comunidade fixa de baixa renda, denominada Parque UniversitÃrio. No presente estudo, foi realizado outro corte transversal aproximadamente oito anos apÃs a anÃlise inicial nesse mesmo grupo de crianÃas, com o objetivo de avaliar a dinÃmica da infecÃÃo e se as crianÃas infectadas sÃo mais susceptÃveis a terem anemia, deficiÃncia de ferrritina, folato e vitamina B12 do que as nÃo infectadas. A infecÃÃo por H. pylori foi avaliada em 133 crianÃas por meio do teste respiratÃrio, previamente validado para a populaÃÃo brasileira. Foram coletadas amostras de sangue em 108 crianÃas para a realizaÃÃo de hemograma e a dosagem de concentraÃÃes sÃricas de ferritina, vitamina B12 e folato por meio da tÃcnica de quimioluminescencia utilizando Immulite  2000. A prevalÃncia da infecÃÃo por H. pylori nas crianÃas foi de 53,4% (71/133) em 2000, enquanto a prevalÃncia de H. pylori nas mesmas crianÃas em 2008 foi de 64,7% (86/133). ApÃs 8 anos, a maioria (88,7%) das crianÃas H. pylori positivas permaneceram infectadas. A taxa de aquisiÃÃo da infecÃÃo por H. pylori apÃs 8 anos da anÃlise inicial foi de 17,3% (23/133) e a taxa de cura espontÃnea da infecÃÃo foi de 6% (8/133). As taxas de aquisiÃÃo foram maiores em crianÃas com idade de 10 anos ou menos, atingindo 30,2% em crianÃas menores de 5 anos. A prevalÃncia da infecÃÃo em crianÃas com menos de 5 anos aumentou de 39.6% em 2000 para 62,2% em 2008 (p=0,020). NÃo houve diferenÃa estatisticamente significante entre anemia, concentraÃÃes sÃricas de ferritina, vitamina B12 e folato em indivÃduos H. pylori positivos comparados aos H. pylori negativos. Em conclusÃo, a infecÃÃo por H. pylori à adquirida precocemente na infÃncia, com altas taxas de aquisiÃÃo em crianÃas com 10 anos ou menos. NÃo foi encontrado associaÃÃo entre a infecÃÃo por H. pylori e anemia, nÃveis sÃricos de vitamina B12, ferritina e folato / Helicobacter pylori infection is one the most prevalent infections in the world. There is a strong evidence that it is acquired in childhood. Therefore epidemiological studies in children are essential to understand the dynamics of this infection and also to evaluate the possible consequences of H. pylori infection in children. Previously it was evaluated the prevalence of H. pylori in children up to fourteen years of age at a low-income community called Parque UniversitÃrio. The present study is a cohort of a group of children eight years after the first study, with the aim of evaluating the dynamics of H. pylori infection and also to check if infected children are more likely to have anemia and ferrritin, folate and vitamin B12 deficiency when compared to non-infected children. The infection was evaluated in 133 individuals through the 13C urea breath test, previously validated for the brazilian population. Blood was sampled from 108 individuals to dose levels of ferritin, vitamin B12 and folate by chemiluminescence using Immulite  2000 and hemoglobin. The prevalence of H. pylori infection in the individuals was 53.4% (71/133) in 2000, while the prevalence of H. pylori in the same group in 2008 was 64.7% (86/133). It was found that after eight years, the majority (88.7%) of H. pylori positive individuals remained positive for infection. The rate of acquisition of infection by H. pylori after 8 years of the initial analysis was 17.3% (23/133) and the rate of loss of infection was 6% (8/133). The acquisition rates were higher in children younger than 10 years, reaching 30.2% in children younger than 5 years. The prevalence of infection in children under 5 years increased from 39.6% in 2000 to 62.2% in 2008 (p = 0.020). There was no statistically significant difference between anemia, serum ferritin, vitamin B12 and folate in H. pylori-positive individuals compared to H. pylori-negative. In conclusion, H. pylori infection is acquired early in childhood, with high rates of acquisition in children under 10 years. There was no association between H. pylori infection and anemia, serum vitamin B12 and folate levels among the individuals studied. / Helicobacter pylori infection is one the most prevalent infections in the world. There is a strong evidence that it is acquired in childhood. Therefore epidemiological studies in children are essential to understand the dynamics of this infection and also to evaluate the possible consequences of H. pylori infection in children. Previously it was evaluated the prevalence of H. pylori in children up to fourteen years of age at a low-income community called Parque UniversitÃrio. The present study is a cohort of a group of children eight years after the first study, with the aim of evaluating the dynamics of H. pylori infection and also to check if infected children are more likely to have anemia and ferrritin, folate and vitamin B12 deficiency when compared to non-infected children. The infection was evaluated in 133 individuals through the 13C urea breath test, previously validated for the brazilian population. Blood was sampled from 108 individuals to dose levels of ferritin, vitamin B12 and folate by chemiluminescence using Immulite  2000 and hemoglobin. The prevalence of H. pylori infection in the individuals was 53.4% (71/133) in 2000, while the prevalence of H. pylori in the same group in 2008 was 64.7% (86/133). It was found that after eight years, the majority (88.7%) of H. pylori positive individuals remained positive for infection. The rate of acquisition of infection by H. pylori after 8 years of the initial analysis was 17.3% (23/133) and the rate of loss of infection was 6% (8/133). The acquisition rates were higher in children younger than 10 years, reaching 30.2% in children younger than 5 years. The prevalence of infection in children under 5 years increased from 39.6% in 2000 to 62.2% in 2008 (p = 0.020). There was no statistically significant difference between anemia, serum ferritin, vitamin B12 and folate in H. pylori-positive individuals compared to H. pylori-negative. In conclusion, H. pylori infection is acquired early in childhood, with high rates of acquisition in children under 10 years. There was no association between H. pylori infection and anemia, serum vitamin B12 and folate levels among the individuals studied.

Background: Preterm birth is one of the leading causes of perinatal mortality and morbidity and poses extensive economic liability. The rate of preterm births globally is approximately 11.1%, and in the US, the preterm birth rate has been estimated to be 12-13%. Folate and B12 requirements increase during pregnancy as a result of increased cell division to accommodate maternal and fetal growth; inadequate levels can result in placental abnormalities and thus present implications for preterm birth. Objective: To investigate the association between red blood cell (RBC) folate and B12 concentrations with the risk of preterm birth. Methods: Study participants were recruited from Tampa General Hospital between January 2011 and May 2013. Women with a singleton delivery occurring less than 37 weeks gestation were classified as cases and those with a singleton delivery occurring between 37 and 42 weeks gestation were classified as controls. The study had a final sample size of 227 women, including 36 cases and 191 controls. Maternal blood was collected in order to measure folate and B12 concentrations. The association between folate/B12 and preterm birth was assessed using logistic regression; odds ratio (OR), 95% confidence interval (CI) and p values are reported. A power analysis was also performed using the available sample as well as imputation for missing values in the B12 variable. Results: Although not statistically significant, the mean concentration of folate and B12 levels were higher in the cases than in the controls, 894 ± 158.1 vs. 869.2 ± 169.6 and 245.2 ± 102.2 vs 238.3 ± 81.5, respectively. No significant associations were found between folate or B12 and the risk of preterm birth. Conclusions: This study did not detect a significant association between folate or B12 and preterm birth; however, due to the small sample size this analysis was underpowered. Additional studies are needed, preferably using a randomized control study design, in order to elucidate the relationship between folate/B12 and preterm births.

Mexico has a high prevalence of stunting in children and adolescents, due to poor nutrition. Paradoxically, too many Mexican children and adolescents are currently overweight or obese (OW/OB). The dual-burden of stunting (low height for age) and OW/OB are nutritional conditions that increase the risk of developing chronic degenerative diseases in adulthood. The persistence of high levels of stunting in southern regions of Mexico, such as Yucatan, may be due to diet changes (nutrition transition) that Yucatecan population has experienced in recent years. Vitamins, such as folic acid (FA) and VB12 are micronutrients necessary for normal metabolism and growth. The relationships between the intake of these micronutrients and growth rate were identified. The impact of micronutrient consumption on body composition was also investigated. The sample population comprised 273 adolescents (152 females) aged 10-18 years, from Merida, Mexico. Dietary information was obtained using a food frequency questionnaire (FFQ) covering 106 local foods. Anthropometric and body composition measurements were taken, and socioeconomic data were gathered. Data were collected between September 2011 and July 2012. Over 50% of participants had inadequate consumption of both vitamins: 64% had inadequate intake of FA and 69% of VB12. Almost half (46.9%) were either short or stunted, and 33% were at risk of OW/OB. A higher risk of presenting OW/OB was found for participants with FA intake less than the RDI of 400 μg/day and for those with VB12 intake less than the RDI of 2.4 μg/day. No relationship was found between body fat percentage and the consumption of FA or VB12.

Manganese-deficient Streptococcus sanguinis mutants exhibit a dramatic decrease in virulence for infective endocarditis and in aerobic growth in manganese-limited media. Loss of activity of a manganese-dependent, oxygen-dependent ribonucleotide reductase (RNR) could explain the decrease in virulence. When the genes encoding this RNR are deleted, there is no growth of the mutant in aerobic broth culture or in an animal model. Testing the contribution of the aerobic RNR to the phenotype of a manganese transporter mutant, a heterologous class II RNR from Lactobacillus leichmannii called NrdJ that requires B12 rather than manganese as a cofactor was previously introduced into an RNR mutant of S. sanguinis. Aerobic growth was only partially restored. Currently, we sought to improve NrdJ-dependent growth by (i) amending the medium to increase cellular levels of B12; (ii) characterizing a spontaneous mutant of the NrdJ-complemented strain with improved aerobic growth; and (iii) altering this strain through further genetic manipulation.

The fully halogenated or hydrogenated B12X12²- (X = H, F, Cl, Br and I) clusters are confirmed to be icosahedral.Onthe other hand, the bare B12 cluster is shown to have a planar structure.Aprevious study showed that a transformation from an icosahedron to a plane happens when 5 to 7 iodine atoms are remained [P. Farràs et al., Chem. - Eur. J. 18, 13208–13212 (2012)]. Later, the transition was confirmed to be seven iodine atoms based on an infrared spectroscopy study [M. R. Fagiania et al., Chem. Phys. Lett. 625, 48–52 (2015)]. In this study, we investigated the effects of different halogen atoms on the opening of the B12 icosahedral cage by means of density functional theory calculations.We found that the halogen elements do not have significant effects on the geometries of the clusters. The computed infrared (IR) spectra show similar representative peaks for all halogen doped clusters. Interestingly, we found a blue-shift in the IR spectra with the increase in the mass of the halogen atoms. Further, we compared the Gibbs free energies at different temperatures for different halogen atoms. The results show that the Gibbs free energy differences between open and close structures of B12X7- become larger when heavier halogen atoms are presented. This interesting finding was subsequently investigated by the energy decomposition analysis.

No description available.

In dieser Arbeit wird ein neuer Ansatz beschrieben, elektroaktive Verbindungen auf mesoporösen Elektroden zu fixieren. Dies wurde durch die Bildung eines sich selbst organisierenden Monolayers auf der Innenseite eines mesoporösen Trägers (ITO, FTO, ATO, TiO2) erreicht. Dieser Layer wurde dann vernetzt und in Richtung des Porenzentrums weiter aufgebaut durch Substitutions- Kondensations- oder Elektropolymerisations- Reaktionen. Es wurde ein Vernetzungsverfahren entwickelt, welches die Herstellung stabiler elektrochromer Bilder mit verbessertem Kontrast und einer Haltbarkeit von mehr als 18 Monaten erlaubt. Es beinhaltet die Synthesen von molekularen Einheiten mit latent vorhandenen oder voll entwickelten elektrochromen Eigenschaften. Diese Einheiten waren 4,4´- Bipyridine, die entweder mit optionalen N-Alkyl, N-Benzyl oder N-Phenyl Gruppen mit nukleophilem oder elektrophilen Eigenschaften oder mit TiO2 Ankergruppen versehen waren. Die Kaskadenreaktion ergab Elektroden mit unterschiedlichen Oberflächenkonzentrationen und unterschiedlichen Pimerisationsgraden. Darüber hinaus gelang es, die Haltbarkeit und den Kontrast so weit zu steigern, dass sie kommerziellen Ansprüchen genügen. Die Optimierung der Gegenelektroden wurde durch ein ähnliches Verfahren unter Verwendung von Ferrocen- Derivaten erreicht. Die Ladungskapazitäten, die durch Multilayer Vernetzung auf ATO-Ferrocen Elektroden erhalten wurden, waren hervorragend mit Ausnahme der Tatsache dass ein schwach grüner Farbton, verursacht durch oxidiertes Ferrocen, vorhanden war. Schließlich wurde die Kaskadenreaktion auf B12 Derivate zur Herstellung von katalytisch aktiven TiO2 Elektroden angewandt. Die mit B12 modifizierten Elektroden zeigten verbesserte Stabilität, höhere turn over - Zahlen und größere turn over -Raten im Vergleich zu unvernetzten B12 modifizierten Elektroden.

No description available.

<p>Small molecule metabolites have important and diverse roles in every major cellular function. To study the activities of metabolites and the biological processes in which they are involved, it is important to be able to detect their levels within cells. Technologies that measure the concentrations of small molecules within the context of living, growing cells are highly advantageous but are challenging to produce. In this thesis, a novel class of intracellular small molecule sensors is produced, characterized and applied to address novel and relevant research questions. These sensors detect a specific target molecule within bacterial cells using RNA regulatory elements known as riboswitches and one of many possible reporter proteins. In addition to a project that yielded new methodology to create custom riboswitches, two projects that assess the capabilities of sensors that detect an active form of vitamin B12 are described. These projects present an abundance of data that provide novel insights into the transport and metabolism of vitamin B12 in <em>E. coli</em> cells. Overall, the results presented indicate that riboswitch-based sensors represent valuable and unique tools for the study of microbial biology. The thesis is concluded with a discussion that describes design strategies and several exciting potential applications for future riboswitch sensors.</p> / Doctor of Philosophy (PhD)