Methionine synthase (MS) is a vitamin B12(cobalamin;cbl) dependent enzyme that catalyses the methylation of homocysteine to methionine. It uses methyl-cbl as coenzyme and in ethyl tetrahydrofolate as the methyl donor. Methionine sythase reductase (MSR) maintains MS in it active state using S-adenosyl methionine as the methyl donor. Functional MS deficiency may occur as a result of a defect in either enzyme. Patients with this disorder have been classified into two complemetation groups according to which protein is defective: cblG patients are deficient in MS and cblE patients in MSR. A subset of cblG, known as cblG variant, is unique in showing barely detectable MS activity and failure of cbl incorporation into MS in patient fibroblasts. I report the mutations responsible for three cblG variant patients, two of them siblings, and connect their phenotype to lack of protein expression. I also report the cloning of the MSR cDNA, aided by confirming the identity of the cDNA through the discovery of two deleterious mutations in three cblE patients. These findings contribute to the overall understanding of functional MS deficiency.

We have studied the effect of S-adenosylmethionine (SAM) on tail flick latency in the rat. We also studied the effect of methionine the immediate precursor of SAM. Administration of methionine to the rat increases brain SAM, but little is known about its behavioral effects. Long-Evans rats were given SAM and methionine orally at different doses and tail-flick latency was measured at various times. Both methionine and SAM increased tail-flick latency, but methionine did so at a lower dose. A biochemical study showed that methionine was more effective than SAM in raising brain SAM probably because it is transported better into brain. The biochemical measurements were not consistent with the idea that the effects of SAM and methionine were mediated by an increase in brain 5-HT. / Folate deficiency can lower brain SAM levels and cause depression. Thus, methionine, which raises brain SAM, may overcome the effects of folate deficiency. Seven day food records were done by 26 psychiatric outpatients who were stable on lithium treatment. Eight patients had mean daily folate intakes below those recommended. Some of those with low folate intake had high methionine intake consistent with the idea that methionine could substitute metabolically for folate deficiency. Daily methionine intakes ranged from 13 to 304% of the recommended intake. As methionine had behavioral effects in the rat at doses much less than the daily dietary intake this raises the question of whether varying daily intakes of methionine in humans have behavioral implications. (Abstract shortened by UMI.)

Diss. (sammanfattning) Stockholm : Karol. inst., 2006. / Härtill 4 uppsatser.

Thesis (M.S.)--University of Missouri-Columbia, 2007. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on May 12, 2009) Includes bibliographical references.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1970. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliography.

Made available in DSpace on 2014-06-11T19:32:58Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-08-08Bitstream added on 2014-06-13T19:22:52Z : No. of bitstreams: 1 stradiotti_ac_dr_botfmvz.pdf: 360994 bytes, checksum: f73e9fbf31a16ecd20608d86fb5a13c4 (MD5) / O presente trabalho teve como objetivo utilizar a técnica de isótopos estáveis para avaliar a taxa de incorporação do carbono-13, proveniente da L-metionina, nos tecidos de frangos de corte em crescimento. Foram alojados em galpão experimental 1000 pintos de corte machos da linhagem Cobb, sendo distribuídas 51 aves, após seleção por peso em cada um dos seis grupos (G) avaliados: período de 1 a 7 (G1), 8 a 14 (G2), 15 a 21 (G3), 22 a 28 (G4), 29 a 35 (G5) e 36 a 42 (G6) dias de idade. As aves foram submetidas à administração via oral de solução contendo L-[13C1]metionina (abundância isotópica de 99 atm % em 13C), na dosagem de 29 μmol/kg peso vivo/h, durante 6 h. Nos tempos 0 h (controle); 0,5; 1; 2; 3; 4; 5; 6; 8; 10; 12; 16; 20; 24; 48; 72 e 96 h após a primeira administração de solução enriquecida, foram abatidas 3 aves por tempo em cada período, para amostragem dos tecidos utilizados nas análises isotópicas em espectrômetro de massa. Foram coletadas amostras de mucosa duodenal (M), plasma sanguíneo (PL), fígado (F), coxa (C), sobrecoxa (SC), peito (PE), penas (PN) e gordura abdominal (GA). Os dados obtidos foram analisados utilizando o software estatístico Minitab 16 (2010). Nas condições experimentais não foi detectada incorporação na GA em nenhum período avaliado, bem como para os períodos G5 e G6 das PN. O tempo de máxima incorporação do carbono-13, proveniente da L-metionina, nos tecidos M, PL e F, ocorreu por volta de 9 horas e para os tecidos C, SC, PE e PN, ocorreu por volta de 17 horas, após a administração das dosagens. O tecido da M apresentou o menor valor de meia-vida encontrado quando comparado aos demais (1,9 a 3,7 horas), indicando maior rapidez na metabolização. A taxa de incorporação do carbono-13, proveniente da L-metionina, nos tecidos avaliados varia em cada período de crescimento... / This study aimed to use the technique of stable isotopes to assess the rate of incorporation of carbon- 13 , derived from L- methionine , in the tissues of broiler growing . They were housed in experimental shed 1000 male broiler chicks of Cobb , 51 birds being distributed after selection by weight in each of the six groups (G ) evaluated period 1-7 ( G1 ) , 8-14 ( G2 ) , 15 to 21 (G3 ), 22 to 28 ( G4 ) 29 to 35 ( G5) and 36 to 42 ( G6 ) days of age . The birds were subjected to oral administration of a solution containing L- [ 13C1 ] methionine ( isotopic abundance of 99 atm % 13C ) , at a dose of 29 mmol / kg body weight / h for 6 h . At 0 h (control) , 0.5 , 1, 2 , 3, 4 , 5, 6 , 8, 10 , 12, 16 , 20, 24 , 48, 72 and 96 hours after the first administration of enriched solution , 3 birds were slaughtered for each time period for sampling of the fabrics used in isotopic analysis in the mass spectrometer . Samples were taken from the duodenal mucosa ( M ) , plasma ( PL ) , liver ( F ) , thigh ( C ) , drumstick ( SC ) , chest ( PE ) , feathers ( PN ) and abdominal fat ( GA ) . The data were analyzed using the statistical software Minitab 16 (2010 ) . Under the experimental conditions was not detected in any GA incorporation into the evaluation period , and the periods of the PN G5 and G6 . The time of maximum incorporation of carbon -13 from L- methionine, tissue M and F PL , occurred at about 9 hours to tissues and C SC, PE and PN occurred around 17 hours after administration of dosages . The fabric of M with the lowest value found half-life compared to the other ( from 1.9 to 3.7 hours) , indicating a faster metabolism . The rate of incorporation of carbon -13 from L- methionine, assessed the tissue varies in each period of growth of the birds. The stable isotope technique proves... (Complete abstract click electronic access below)

D-methionine (D-met) has demonstrated otoprotection from noise-, aminoglycoside-, and cisplatin-induced hearing loss in animal studies. As a result, D-met is currently progressing through translational "bench to bedside" research. However, D-met's exact otoprotective mechanisms have not been fully elucidated. This study investigated relationships between dose- and time-dependent D-met otoprotection from noise- and aminoglycoside-induced hearing loss. Further, the study correlated protective D-met dose to endogenous antioxidant enzyme activity and lipid peroxidation. Specific aim 1 tested D-met dose response protection by auditory brainstem response (ABR) threshold shift analysis and outer hair cell (OHC) quantification. D-met doses ranging from 25-200 mg/kg/dose were administered to chinchillas every 12 hours five times each before and after steady state noise exposure totaling 10 D-met doses. Results demonstrated optimal, sub-optimal, and supra-optimal bi-phasic D-met otoprotective dose response. Optimal D-met protection from steady state noise occurred at the 50 mg/kg/dose level. OHC quantification confirmed electrophysiological assessment. Specific aim 2 measured D-met rescue protection from steady state noise exposure by ABR threshold shift analysis and OHC quantification. Five intraperitoneal (ip) D-met injections were administered every 12 hours beginning 3, 5, 7, 9, 12, 18, 24, 36, or 48 hours after steady state noise exposure. Results measured full D-met protection when administration began as late as 24 hours after noise secession. Significant partial protection was also measured for the 36 hour delay. OHC quantification confirmed electrophysiological assessment. Specific aim 3 measured D-met preloading protection from steady state noise exposure by ABR threshold shift analysis and OHC quantification. Five ip D-met injections were administered every 12 hours beginning 2, 2.5, or 3 days prior to steady state noise exposure. Results measured significant D-met protection when administration ended as early as 24 hours prior to noise exposure. OHC quantification confirmed electrophysiological assessment. Specific aim 4 tested dose-dependent D-met influence on antioxidant enzyme activity and oxidative stress in steady state noise-exposed chinchillas. One ip D-met injection, ranging from 25 to 200 mg/kg/dose, was administered every 12 hours beginning 2 days prior to steady state noise exposure for a total of 5 injections. Two hours post-noise exposure, animals were sacrificed and serum, liver, and cochleae were collected for endogenous antioxidant analysis. Glutaredoxin 2 (Grx2) was also analyzed 21 days post-noise exposure. Lower D-met doses (25 and 50 mg/kg/dose) increased superoxide dismutase and catalase activity. Glutathione reductase and glutathione peroxidase activities significantly increased with D-met doses but only at high concentrations (200 mg/kg/dose). At 21 days post-noise, Grx2 activity was significantly decreased in liver but greatly increased in the cochlea with high D-met doses (200 mg/kg/dose). The endogenous enzyme studies suggest optimal protective D-met dose determined in specific aims 1 through 3 may be secondary to increased superoxide dismutase and catalase activity which may result from D-met's free radical scavenging characteristics. Glutathione pathway activity increased only with high D-met doses that resulted in less optimal protection in specific aim 1. Thus, D-met-induced glutathione pathway enhancement may be a compensatory or saturation mechanism rather than the primary protective mechanism. Further, the extended pre-loading and rescue protection may be a result of significantly increased s-glutathionylation activity in the cochlea. Specific aim 5 tested D-met protection from impulse noise exposures. D-met dose response, rescue, and antioxidant enzyme assay protocols, similar to those in specific aims 1, 3, and 4 in steady state animals, were performed on impulse noise-exposed chinchillas. D-met provided dose- and time-dependent optimal protection from impulse noise similar to the steady-state noise studies. Optimal D-met protection was measured at the 100 mg/kg/dose level with complete rescue protection as late as 24 hours post-noise exposure. Endogenous enzyme activity measures demonstrated significant superoxide dismutase, catalase, and glutathione peroxidase activity increases which correlated with optimal D-met protective dose (100 mg/kg/dose) and catalase and superoxide dismutase activity decreases at the higher doses (200 mg/kg/dose). Specific aim 6 tested dose-dependent D-met protection from tobramycin, amikacin, kanamycin, and gentamicin aminoglycoside antibiotics. Guinea pig animal models were normalized to achieve a 30-40 dB ABR threshold shift with the lowest possible aminoglycoside dose. D-met and the aforementioned single aminoglycoside were administered for 21, 28, 23, or 14 days, respectively. ABRs were collected and assessed at baseline, 2, 4, and 6 weeks after drug administration initiation. After the 6-week ABR data collection, cochleae were collected and prepared for OHC quantification. ABR threshold shifts and OHC quantifications demonstrate significant bi-phasic D-met-induced protection from each aminoglycoside type with different D-met doses. OHC quantification confirmed electrophysiological assessment. This study identified optimal protective D-met dose for aminoglycoside- and noise- induced ototoxicity. It also identified optimal protective D-met dose timing for steady state and impulse noise-induced hearing loss. Further, this study has identified dose-dependent D-met-induced endogenous antioxidant changes and Grx2 enhancement, and therefore s-glutathionylation, as a potential mechanism for D-met protection. Thus, dose- and time-dependent D-met protection influences endogenous antioxidant activity, but exact optimal D-met protection will continue to warrant further investigation.

Made available in DSpace on 2014-06-11T19:28:23Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-02-17Bitstream added on 2014-06-13T19:57:42Z : No. of bitstreams: 1 bonato_ma_me_jabo.pdf: 1088423 bytes, checksum: 706ba8eb71da0975d385cc318b0b96c2 (MD5) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A mantença pode ser definida como o estado em que o animal se encontra em equilíbrio de nitrogênio, no qual a ingestão de N é igual à soma das perdas, permanecendo constante o conteúdo de N do corpo. E esta pode ser definida com base em estudos de metabolismo com aves adultas improdutivas, pelo fato das exigências totais de aminoácidos dessas aves estarem associadas apenas às perdas inevitáveis (mantença), não incluindo necessidades específicas de aminoácidos para o crescimento e/ou produção. Porém, há alguns problemas na determinação da exigência de mantença: primeiro é como comparar a mantença entre genótipos de diferentes tamanhos à maturidade, o segundo é como comparar a mantença entre animais de um mesmo genótipo em diferentes estágios de crescimento, e o terceiro é como lidar com a variação no conteúdo de gordura corporal, uma vez que não existe demanda de aminoácidos para a manutenção das reservas lipídicas. Assim, as diferenças de valores entre níveis de exigências para mantença de aminoácidos encontrados na literatura, tem sido a diretriz para o desenvolvimento de novos estudos, visando à obtenção de metodologias padronizadas e estimativas de valores condizentes com as necessidades das aves. Este estudo teve como objetivo estimar as exigências de metionina+cistina e treonina digestíveis para a mantença de aves adultas utilizando e comparando galos de diferentes pesos e composições corporais / The maintenance can be defined as the state where the animal is in nitrogen balance, in which the intake of N is equal to the sum of the losses, stabilizing the N content in the body. And this can be defined based on studies of metabolism in adult birds unproductive, because the total amino acid requirements of these birds are associated only to the inevitable losses (maintenance), not including the specific amino acids for growth and/or production. However, there are some problems in determining the requirement for maintenance: first is to compare the maintenance among genotypes of different sizes at maturity, the second is like comparing the maintenance of animals of the same genotype at different stages of growth, and the third is how to deal with the variation in body fat content, since there is no demand for amino acids for the maintenance of lipid reserves. Thus, differences in values between levels of requirements for maintenance of amino acids found in the literature has been the guideline for the development of new studies aiming to produce standardized methodologies and estimates of amounts consistent with the needs of birds. This study aimed to estimate the methionine+cystine and threonine digestible for the maintenance of adult birds using and comparing roosters of different weights and body composition

Orientador: Antonio Celso Pezzato / Banca: José Roberto Sartori / Banca: Carlos Ducatti / Banca: Marcos Macari / Banca: José Albertino Bendassolli / Resumo: O presente trabalho teve como objetivo utilizar a técnica de isótopos estáveis para avaliar a taxa de incorporação do carbono-13, proveniente da L-metionina, nos tecidos de frangos de corte em crescimento. Foram alojados em galpão experimental 1000 pintos de corte machos da linhagem Cobb, sendo distribuídas 51 aves, após seleção por peso em cada um dos seis grupos (G) avaliados: período de 1 a 7 (G1), 8 a 14 (G2), 15 a 21 (G3), 22 a 28 (G4), 29 a 35 (G5) e 36 a 42 (G6) dias de idade. As aves foram submetidas à administração via oral de solução contendo L-[13C1]metionina (abundância isotópica de 99 atm % em 13C), na dosagem de 29 μmol/kg peso vivo/h, durante 6 h. Nos tempos 0 h (controle); 0,5; 1; 2; 3; 4; 5; 6; 8; 10; 12; 16; 20; 24; 48; 72 e 96 h após a primeira administração de solução enriquecida, foram abatidas 3 aves por tempo em cada período, para amostragem dos tecidos utilizados nas análises isotópicas em espectrômetro de massa. Foram coletadas amostras de mucosa duodenal (M), plasma sanguíneo (PL), fígado (F), coxa (C), sobrecoxa (SC), peito (PE), penas (PN) e gordura abdominal (GA). Os dados obtidos foram analisados utilizando o software estatístico Minitab 16 (2010). Nas condições experimentais não foi detectada incorporação na GA em nenhum período avaliado, bem como para os períodos G5 e G6 das PN. O tempo de máxima incorporação do carbono-13, proveniente da L-metionina, nos tecidos M, PL e F, ocorreu por volta de 9 horas e para os tecidos C, SC, PE e PN, ocorreu por volta de 17 horas, após a administração das dosagens. O tecido da M apresentou o menor valor de meia-vida encontrado quando comparado aos demais (1,9 a 3,7 horas), indicando maior rapidez na metabolização. A taxa de incorporação do carbono-13, proveniente da L-metionina, nos tecidos avaliados varia em cada período de crescimento... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This study aimed to use the technique of stable isotopes to assess the rate of incorporation of carbon- 13 , derived from L- methionine , in the tissues of broiler growing . They were housed in experimental shed 1000 male broiler chicks of Cobb , 51 birds being distributed after selection by weight in each of the six groups (G ) evaluated period 1-7 ( G1 ) , 8-14 ( G2 ) , 15 to 21 (G3 ), 22 to 28 ( G4 ) 29 to 35 ( G5) and 36 to 42 ( G6 ) days of age . The birds were subjected to oral administration of a solution containing L- [ 13C1 ] methionine ( isotopic abundance of 99 atm % 13C ) , at a dose of 29 mmol / kg body weight / h for 6 h . At 0 h (control) , 0.5 , 1, 2 , 3, 4 , 5, 6 , 8, 10 , 12, 16 , 20, 24 , 48, 72 and 96 hours after the first administration of enriched solution , 3 birds were slaughtered for each time period for sampling of the fabrics used in isotopic analysis in the mass spectrometer . Samples were taken from the duodenal mucosa ( M ) , plasma ( PL ) , liver ( F ) , thigh ( C ) , drumstick ( SC ) , chest ( PE ) , feathers ( PN ) and abdominal fat ( GA ) . The data were analyzed using the statistical software Minitab 16 (2010 ) . Under the experimental conditions was not detected in any GA incorporation into the evaluation period , and the periods of the PN G5 and G6 . The time of maximum incorporation of carbon -13 from L- methionine, tissue M and F PL , occurred at about 9 hours to tissues and C SC, PE and PN occurred around 17 hours after administration of dosages . The fabric of M with the lowest value found half-life compared to the other ( from 1.9 to 3.7 hours) , indicating a faster metabolism . The rate of incorporation of carbon -13 from L- methionine, assessed the tissue varies in each period of growth of the birds. The stable isotope technique proves... (Complete abstract click electronic access below) / Doutor

Certaines formes d'épilepsies nécessitent encore d'être étudiées pour pouvoir être traitées. Le modèle d'animaux épileptiques développé par le Laboratoire de Neurobiologie est constitué des lignées MSO-Fast et MSO-Slow, convulsant respectivement rapidement ou tardivement après l'injection de méthionine sulfoximine (MSO). Ce travail a pour but d’analyser et de comparer ces deux lignées afin de mieux comprendre les mécanismes contribuant à l’apparition des crises induites par la MSO. Les deux lignées ont d'abord été caractérisées par leurs réponses à la MSO. L'implication de la voie glutamatergique a ensuite été mise en évidence par l'administration de convulsivants et d'anticonvulsivants ainsi que par une étude de l'anxiété et de la faculté d'apprentissage. L'étude de la glutamine synthétase, enzyme-clé du recyclage du glutamate en tant que neurotransmetteur, a révélé une plus faible activité de cette enzyme pour la lignée MSO-Fast. La mesure de la variation du taux de glycogène astrocytaire indique que le métabolisme glucidique, lié étroitement à la voie glutamatergique, participe à la différence de sensibilité entre les deux lignées. Une étude complémentaire de la glycosylation des protéines a révélé une modification de la N-glycosylation induite par une dose convulsivante de MSO. Les concentrations de 13 molécules appartenant à la famille des monoamines ont été mesurées par HPLC. Cette étude démontre d'une part la forte diminution de tryptophane et de tyrosine après injection de MSO et d'autre part l'implication de la noradrénaline et de la sérotonine, les deux principaux neurotransmetteurs contrôlant la quantité de glycogène astrocytaire. / Certain forms of epilepsies still require understanding their mechanisms to be treated. The model of epileptic animals developed by the Laboratory of Neurobiology is constituted by the lines MSO-Fast and MSO-Slow, convulsing respectively quickly or late after the injection of methionine sulfoximine (MSO). This work aims at analyzing and at comparing these two lines to better understand mechanisms contributing to the appearance of the crises induced by MSO. Both lines were characterized at first by their answers to MSO. The implication of the glutamatergic neurotransmission was then revealed by the administration of convulsants and anticonvulsants as well as by a study of the anxiety and the faculty of learning. The study of the glutamine synthetase, the key-enzyme of the the neurotransmitter glutamate recycling, revealed a lower activity of this enzyme for the line MSO-Fast. The measure of the variation of astrocyte glycogen indicates that the glucidic metabolism, connected to the glutamatergic pathway, participates to the difference of sensibility between both lines. The study of the glycoproteins revealed a modification of N-glycosylation linked to a convulsante dose of MSO. The concentrations of 13 molecules belonging to the family of monoamines were measured by HPLC. This study demonstrates on one hand the strong decrease of tryptophane and tyrosine after injection of MSO and on the other hand the implication of norepinephrine and serotonine, two main neurotransmitters controlling the quantity of astrocyte glycogen.