Thesis (M Med (Chemical Pathology)) -- University of Limpopo, 2012. / Abstract Aim: This study was undertaken to compare the diagnostic sensitivity and specificity of total vitamin B 12 analyses to active B 12 (holoTC) analyses in a population of patients attending the Dr George Mukhari Hospital in Pretoria. Methods: Routine serum folate, full blood count (FBC), thyroid function test, homocysteine, serum total vitamin B 12 and active B 12 analyses were performed on 30 samples. Results: Serum folate was determined in all patients and 96% of the patients had a normal folate value. When looking at the FBC results it is important to note that three times as many males as females presented with anemia (36% versus 16%). Thyroid function tests were normal in 90% of patients. When the total vitamin B 12 test was preformed only 10% of patients tested positive for vitamin B 12 deficiency, in contrast to the active B12 analyses where 16% of patients tested positive for vitamin B12 deficiency. Both tests had a diagnostic sensitivity of 50%. The diagnostic specificity for total vitamin B12 was 93% in comparison with the 86% obtained by the active B12 analyses; when homocysteine was used as the true marker for vitamin B12 deficiency. Conclusion: Diagnostic sensitivity was the same and the total vitamin B12 test's specificity was better in comparison to the active B 12 analyses. Thus the active B 12 assay cannot be recommended for routine use, since it has no benefit.

No description available.

Fibroblasts from patients with functional methionine synthase deficiency can be divided into 2 complementation classes, cblE and cblG. Both have low levels of intracellular methylcobalamin. Both groups also demonstrate low levels of incorporation of label from 5-methyltetrahydrofolate into macromolecules. Under standard reducing conditions, methionine synthase specific activity is normal in cblE fibroblast extracts, but is low in cblG fibroblast extracts. Seven cblE and seven out of ten cblG cell lines demonstrate levels of accumulation of ($ sp{57}$Co) CN-Cbl in fibroblasts comparable to that of control cells. They exhibit similar proportions of label associated with the two intracellular cobalamin binders, methylmalonyl-CoA mutase and methionine synthase. The remaining three cblG cell lines exhibit a lower level of cobalamin accumulation, and demonstrate a lack of cobalamin association with the enzyme methionine synthase. The specific activity of methionine synthase is almost undetectable in the three cblG cell lines that showed no such association. These results demonstrate heterogeneity within the cblG group and suggest that the defect in cblG affects the methionine synthase apoenzyme.

Thesis (M.Sc. (Biochemistry)) -- Mahidol University, 1970.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1952. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves [88]-93).

Thesis (M.S.)--University of Wisconsin--Madison, 1971. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (MPhil) -- AUT University, 2008. / Includes bibliographical references. Also held in print (xv, 145 leaves : ill. ; 30 cm.) in the Archive at the City Campus (T 613.2082 XIN)

Thesis (Ph. D.)--University of Wisconsin--Madison, 1952. / Typescript. Vita. Includes 6 reprints by Dietrich, et. al., from various journals. Includes bibliographical references.

Thesis (Ph.D.)--Kent State University, 2010. / Title from OhioLINK ETD abstract webpage (viewed Apr. 28, 2010). Advisor: Nicola E. Brasch. Keywords: Vitamin B12; Cobalamin Metabolism; Oxidative Stress; Reactive Oxygen Species; Cobalamin Synthesis.

Orientador: Ranulfo Monte Alegre / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-07-28T14:47:55Z (GMT). No. of bitstreams: 1 Sampaio_RomildoMartins_D.pdf: 3919745 bytes, checksum: 716e0ca6a5f49638e524df0464557d83 (MD5) Previous issue date: 1999 / Resumo: O presente trabalho trata do estudo da produção de vitamina B12, consistindo das seguintes etapas: seleção do melhor microrganismo produtor; seleção da melhor fonte de substrato, e do meia de cultura, avaliação, modelagem e otimização, das variáveis experimentais e fermentação em reator de bancada, para a obtenção das condições de operação e parâmetros cinéticos que influenciam no rendimento de produção da vitamina. A primeira fase consistiu da seleção do melhor microrganismo produtor a ser utilizado, nos estudos posteriores. Partiu-se das seguintes culturas tidas como boas produtoras de B12: Propionibacterium jensenii DSM 20274, Propionibacterium freudenreichii ATCC 9614, Propionibacterium shermanii ATCC 62Q1, Pseudomonas sp. ATCC 13867 e mais três mutantes isolados. Aqui como nas duas próximas etapas, os ensaios, foram realizados em frascos agitados, com base nos resultados, obtidos, decidiu-se pela seleção do mutante Pseudomonas P3, que chegou a uma produção máxima de 3,86 mg B12/1. A escolha da melhor fonte de substrato e do meio de cultura com composição mais indicada ocorreu paralelamente à escolha do microrganismo. Foram testadas lactose e sacarose e mais três composições de meio: meio 1, meio 2, e meio 3. A sacarose e o meio 1, associados ao mutante selecionado, proporcionaram os melhores rendimentos de B12, produção de biomassa e consumo de substrato. As culturas de. Propionibacterium mostraram maior um maior consumo de lactose do que as Pseudomonas. Na terceira etapa, estudou-se a influência de sete variáveis experimentais, previamente pesquisadas e selecionadas, na produção de B12. Foram elas: idade do inoculo, tempo de fermentação, temperatura, pH, concentração de substrato, de 5,6 DMI e de cobalto. Até a etapa de otimização, foram efetuados um planejamento fracionário, dois planejamentos com composto central e um caminho de ascendência máxima. As variáveis com seus respectivos níveis otimizados, que mais influenciaram a resposta, foram: concentração de 5,6 DMI (98,8 mg/l), temperatura (34,6 °C) e pH (7,14). O planejamento experimental permitiu um aumento de quase. 100% na produção de vitamina, alcançando um máximo de 7,57 mg BI2/1. Os ensaios no fermentador de bancada objetivaram verificar a influência do tempo de adição de 5,6 DMI, KLa e controle de pH no rendimento da vitamina. Concluiu-se que o tempo, ótima de adição, do precursor e a nível de Kls mais, indicado, foram respectivamente, 48 h e 36,8 h-1. Por outro lado, percebeu-se que o controle do pH não melhorou, a produção de vitamina nem aumentou, a velocidade de crescimento do microrganismo / Abstract: The present deals with the study of the production of vitamin B12, consisting of the following stages: selection of the best producing microorganism, selection of the best substrate, source, and the more, suitable medium of culture; evaluation, modeling and optimization of the experimental variables and; fermentation in a bench-fermentor for the obtaining of the operation, conditions and. kinetic parameters that, influence, the yield of the vitamin. The first phase consisted of the selection of the best producer microorganism to be used during the work. The following strains were used: Propionibacterium freudenreichii AICC 9614, Propiombacleruan jensenii. DSM 20274, Propianibacterium shermanii ATCC 6207, Pseudomonas sp. ATCC 13867 and more three mutants isolated. Here as in o stages, the experiments were, conducted in shake-flasks Based on the obtained results, the mutant Pseudomonas P3 was selected, producing a maximum of 3.86 mg BJ2/L. The selection of the best, substrate source, and medium composition was done parallelly to the microorganism selection. Were tested sucrose, lactose and three compositions of medium: medium 1 medium 2 and medium 3. The sucrose and medium 1, associated to the mutant P. P3, provided the best yields of B12, biomass production and substrate consumption. The strains of Propionibacterium showed larger ability in the lactose degradation than Pseudomonas and its mutants. In the third stage it was studied the influence of seven experimental variables in the production of vitamin B12: age of inoculum, time of fermentation, temperature, pH, substrate concentration, 5,6 Dimethylbenzimidazole (DMT> concentration and cobalt concentration. Up to the optimization step were realized a fractional factorial design, a steepest ascent path and two central composite design The most significant parameters, with respective optimized levels, were: 5,6 DMI (98.8 mg/L), temperature (34.6 °C) and pH (7-14)-. The experimental design allowed an. increase of almost 100% in. the Vitamin production, reaching a maximum of 7.57 mg B12/L. The experiments in the bench-fermentor were done to verify, the influence of the time of addition of 5,6 DMI, Kla and pH control in the yield of vitamin B12. The better time of addition and level of KLa, were respectively 48 hr and 36.8 hr-1. The control of pH did not improve the vitamin production / Doutorado / Doutor em Engenharia de Alimentos