Thesis (Ph. D.)--University of Queensland, 2002. / Includes bibliographical references.

Diss. (sammanfattning) Göteborg : Göteborgs universitet, 2007. / Härtill 4 uppsatser.

Abstract not available

Thesis (Ph.D.)--University of Tennessee Health Science Center, 2007. / Title from title page screen (viewed on July 28, 2008). Research advisor: Burt M. Sharp M.D. Document formatted into pages (viii, 81 p. : ill.). Vita. Abstract. Includes bibliographical references (p. 61-81).

Thesis (Ph. D.)--University of Missouri--Columbia, 1998. / "May 1998." Typescript. Vita. Includes bibliographical references (leaves 176-210). Also available on the Internet.

Mitochondrial and supernatant glutamate-oxalacetate transaminases (EC 2.6.1.1) and supernatant glutamate-pyruvate transaminase (EC 2.6.1.2) were purified 89, 204 and 240-fold respectively, from dolphin muscle. Starch gel electrophoresis of crude and purified perparations revealed that all three enzymes exist as single forms. Km values of a-ketoglutarate, alanine, pyruvate and glutamate for the glutamate-pyruvate transaminase were 0.45, 8.2, 0.87 and 15 mM, respectively. For the glutamate-oxalacetate transaminases, the Km values of a-ketoglutarate, aspartate, oxalacetate and glutamate were 0.76, 0.50, 0.10 and 9.4 mM, respectively, for the mitochondrial form and 0.13, 2.4, 0.06 and 3.2 mM, respectively, for the supernatant form. In all cases, as the assay pH was decreased from pH 7.3, the Km values of the a-keto acids decreased while those of the amino acids increased. This caused the apparent equilibrium constants for the glutamate-oxalacetate transaminases to remain independent of pH. These values were 9.2 and 6.8 for the mitochondrial and supernatant forms, respectively where K'eq = [asPartate][α-ketoglutarate]/[glutamate][oxalacetate]. Studies of the inhibition of the glutamate-oxalacetate transaminases by dicarboxylic acids indicated that these enzymes may be controlled by pools of metabolic intermediates. Three key roles are suggested for the transminases in the energy metabolism of the diving mammal. First, it is believed that a combined action of the transaminases could enhance energy production during hypoxia by providing (1) fumarate from aspartate for the ATP producing reversal of succinate dehydrogenase and (2) α-ketoglutarate from glutamate for the GTP producing succinyl thiokinase reaction. Next, diving mammals probably accumulate more NADH than other mammals during hypoxia. The glutamate-oxalacetate transaminases seem particularly well suited for restoring redox balance via the malate-aspartate cycle after aerobic metabolism is resumed. Finally, since migrating divers oxidize large amounts of stored fats, the combined reactions of the transaminases could be instrumental in providing increased supplies of oxalacetate to condense with the fat derived acetyl CoA in the citrate synthase reaction. / Science, Faculty of / Zoology, Department of / Graduate

Tingan Chen. / "March 2000." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (p. 100-142). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

The purpose of this study was to investigate the association between extracellular basal hippocampal glutamate levels and cognitive function in epileptic patients. We used the zero-flow microdialysis method to measure the extracellular concentrations of glutamate in the epileptogenic and non-epileptogenic hippocampus of 23 awake epileptic patients during the interictal period. All patients underwent extensive neuropsychological testing to assess cognitive functioning prior to probe implantation. Basal glutamate levels in the epileptogenic hippocampus were significantly higher than the non-epileptogenic hippocampus (mean, 11.96 micromolar (µM) versus 2.92 µM, respectively). Elevated basal glutamate levels in the epileptogenic hippocampus correlated with decreased scores on the Verbal Selective Reminding Test (V-SRT) (R[exponent]2 = 0.36, p = 0.0244). When controlling for MRI-detected hippocampal atrophy within epileptogenic regions, elevated basal glutamate levels within atrophic hippocampus correlated with decreased cognitive functioning measured by both the V-SRT (R[exponent]2 = 0.7764, p = 0.0204) and Performance Intelligence Quotient (PIQ) (R[exponent]2 = 0.7324, p = 0.0297), but not within non-atrophic hippocampus (V-SRT: R2 = 0.1013, p = 0.4424; PIQ: R[exponent]2 = 0.2303, p = 0.2288). These data suggest that elevated basal glutamate levels in the epileptogenic hippocampus may be implicated in the pathogenesis of hippocampal atrophy and may contribute to impaired cognitive functioning involving verbal memory and visual-spatial skills in patients with temporal lobe epilepsy.

Alterações na atividade de peptidases no sistema nervoso central (SNC) de adictos a narcóticos, abstinentes dependentes de opióides, diabéticos e indivíduos com desequilíbrio hidrosalino, têm sido achados instigantes no contexto atual dos conhecimentos sobre o balanço energético. Neste sentido, são particularmente interessantes o fenômeno da proteólise irrestrita e o envolvimento de diversos peptídeos do SNC, especialmente no hipotálamo e hipocampo, como as incretinas, neuropeptídeo Y, peptídeo YY, peptídeos derivados da proopiomelanocortina (melanocortinas e beta-endorfinas), somatostatina, vasopressina e angiotensinas. O presente estudo avaliou a hipótese de que aminopeptidases que têm alguns desses peptídeos como substratos, a aminopeptidase neutra (APN) (sensível PSA, e insensível APM/CD13, à puromicina) e a dipeptidil peptidase IV (DPPIV/CD26) (sensível - DPPIV-DS, e insensível - DPPIV-DI à diprotina), poderiam relacionar-se com a obesidade induzida por glutamato monossódico (MSG) e com o estado de privação alimentar. Foram analisadas as expressões gênica e protéica da CD13 e CD26, as atividades enzimáticas de PSA, APM, DPPIV-DS e DPPIV-DI em fração solúvel e de membrana solubilizada, a ativação celular (imuno-reatividade a Fos), a distribuição imuno-histoquímica regional de CD13 e CD26 no hipotálamo e hipocampo e as correlações entre atividades peptidásicas, massa corporal, índice de Lee, massa dos depósitos de gordura periepididimal e retroperitoneal, comprimento naso-anal e glicemia de ratos obesos MSG e normais, sob regime de privação ou alimentação normal. Comparativamente aos controles, os animais MSG apresentaram: (i) aumento da massa absoluta de gordura retroperitoneal, índice de Lee, expressão protéica CD13 membranal do hipocampo, expressão protéica policlonal CD26 membranal do hipotálamo, atividade DPPIV-DI e expressão protéica monoclonal CD26 membranal do hipocampo; e (ii) diminuição da massa corporal absoluta, comprimento nasoanal, expressão gênica de CD13, expressão protéica membranal de CD13, expressão protéica policlonal de CD26 solúvel e membranal, atividades PSA solúvel e DPPIV-DI solúvel e membranal hipotalâmicas e DPPIV-DS membranal do hipocampo. A privação de alimento também influencia alguns destes parâmetros. As correlações entre os parâmetros biométricos confirmaram características deste modelo de obesidade e adicionalmente sugeriram que a deficiência e a sobrecarga relativas de captação de glicose, respectivamente pela gordura periepididimal e retroperitoneal, poderiam estar associadas ao desenvolvimento do diabetes melito tipo 2 no obeso MSG. Confirmou-se a identidade da proteína CD13 com a atividade peptidásica APM. A DPPIV-DI foi identificada como a CD26 canônica. Em geral, o presente estudo evidenciou o envolvimento das atividades PSA, DPPIV-DI e -DS hipotalâmicas (mas não da APM) e das proteínas CD13 e CD26, na regulação endócrina do balanço energético (provavelmente via atuação sobre neuropeptídeo Y, somatostatina e opióides). No hipocampo, o padrão destas alterações foi compatível com efeito deletério sobre memória, aprendizado (PSA e APM) e comportamento emocional (DPPIV-DI e DS). CD13 e CD26 apresentaram ampla distribuição no hipotálamo, a qual, em condições normais, foi coincidente com a imuno-reatividade à Fos nos núcleos supraóptico, periventricular, retroquiasmático e arqueado. Nestas áreas, relacionadas ao controle do balanço energético, ocorreram alterações densitométricas da imuno-reatividade a CD13, CD26 e Fos em função da obesidade MSG e/ou da privação de alimento. Em suma, proteínas com atividades de aminopeptidase neutra 9 ou dipeptidil peptidásica do tipo IV e/ou homólogas à CD13 ou CD26 são fatores fisiopatológicos e alvos farmacológicos potenciais de distúrbios do metabolismo energético. / Alterations of peptidase activity levels in the central nervous system (CNS) in drug addicts, abstinent opioid-dependent, diabetic and subjects with disrupted hydrosaline equilibrium, have been arousing findings in the context of current knowledge about regulatory mechanisms of food intake and energy balance. In this sense, the involvement of leptin, ghrelin, insulin and other peptides in the CNS, including incretins, neuropeptide Y, peptide YY, proopiomelanocortins (melanocortins and _-endorphin), somatostatin and vasopressin, which are susceptible to hydrolysis by aminopeptidases (APs), mainly in the hypothalamus and hippocampus, are particularly interesting. The present work evaluated if aminopeptidase activities involved in the hydrolysis of these peptides, i.e. neutral AP (APN) (sensitive- or insensitive-puromycin AP, PSA or APM/CD13, respectively) and dipeptidyl peptidase IV (DPPIV/CD26) (sensitive- or insensitive-diprotin dipeptidyl peptidase, DPPIV-DS or DPPIVDI, respectively), are associated with monosodium glutamate (MSG) induced obesity and food deprivation. It was analysed the gene and protein expressions of CD13 and CD26, catalytic activities of PSA, APM, DPPIV-DS and DPPIV-DI in soluble and membrane-bound fractions, cellular activation (Fos immunoreactivity) and regional immunohistochemistry distribution of CD13 and CD26, in hypothalamus and hippocampus, and inter-relations among these peptidase activities, body mass, Lee index, mass of epidydimal and retroperitoneal fat pad, naso-anal length and glycemia in normal and obese MSG rats under normal or deprived feeding regimens. Relative to control, MSG presented: (i) increased retroperitoneal mass, Lee index, CD13 protein expression in membrane-bound fraction of hippocampus, CD26 polyclonal protein expression in membrane-bound fraction of hypothalamus, DPPIV-DI activity and CD26 monoclonal protein expression in membranebound fraction of hippocampus; and (ii) reduction of body mass, naso-anal length, CD13 gene expression, CD13 protein expression in membrane-bound fraction, CD26 polyclonal protein expression in soluble and membrane-bound fraction, PSA activity in soluble fraction and DPPIV-DI activity in soluble and membrane-bound fractions of hypothalamus, and DPPIVDS in membrane-bound fraction of hippocampus. Food deprivation also influenced some of these parameters. The correlations between biometric parameters confirmed the characteristics of this obesity model and further suggested that disability and overload on the uptake of glucose, respectively by the epididymal and retroperitoneal fat, could be linked to the development of diabetes mellitus type 2 in obese MSG. CD13 protein identity with APM peptidase activity was confirmed. DPPIV-DI was identified as the canonical CD26 protein. In general, the present work revealed the involvement of PSA, DPPIV-DI and DS hypothalamic activities (but not the APM) and the CD13 and CD26 proteins, in endocrine regulation of energy balance (probably through action on neuropeptide Y, somatostatin and opioids). In the hippocampus, the patterns of these changes were consistent with deleterious effects on memory, learning (PSA and APM) and emotional behavior (DPPIV-DI and DS). CD13 and CD26 presented wide distribution in hypothalamus, which, in normal conditions, is coincident with Fos immunoreactivity in the supraoptic, periventricular, retrochiasmatic and arcuate nuclei. In these areas, related to the control of energy balance, densitometric changes of CD13, CD26 and Fos immunoreactivity occurred according to the obesity MSG and/or food deprivation. Briefly, proteins presenting neutral aminopeptidase or dipeptidyl peptidase IV 11 activities and/or CD13 or CD26 homologous are physiopathological factors and potential pharmacological targets of energetic metabolism disturbances.

A prolina é convertida em glutamato através de dois passos de oxidorredução. Primeiro, prolina é oxidada em D1-pirrolina-5-carboxilato (P5C) que é convertido em glutamato pela TcP5CDH. Neste trabalho demonstrou-se que a enzima TcP5CDH catalisa a oxidação irreversível de gGSA formando glutamato e NADH/NADPH. A TcP5CDH forma um hexâmero que interage com a membrana interna mitocondrial. Os elétrons a partir de NADH abastecem a cadeia transportadora de elétrons para a síntese de ATP. Além disso vimos que a TcP5CDH é regulada positivamente nos estágios infectivos do parasita e, quando esta é induzida pela inserção de uma cópia ectópica, os mutantes apresentam mudanças morfológicas e alterações na expressão da TcGP82. O DSF, reportado como inibidor de aldeído desidrogenasses, interfere na atividade da TcP5CDH, bem como exibiu um efeito tripanocida. Ensaios de RNAi para a TbP5CDH e a análise da expressão desta enzima nas formas do parasita presentes na mosca tsé-tsé também foram discutidos. Os nossos dados reforçam a relevância bioquímica da via prolina-glutamato em T. cruzi, e constituem as primeiras evidências sobre a ocorrência do metabolismo de P5C nessas espécies de tripanossomatídeos. / Proline is converted into glutamate through two oxidorreduction steps. First, prolina is oxidized into D1-pyrroline-5-carboxylate (P5C), which is further converted in glutamate by TcP5CDH. In this work we demonstrate that TcP5CDH catalyzes irreversibly the oxidation of gGSA rendering glutamate and NADH/NADPH. The TcP5CDH undergoes a hexameric conformation interacting with inner mitochondrial membranes. Electrons from NADH fed electron respiratory chain for ATP synthesis. Moreover, we show that TcP5CDH is up regulated in infective stages (M e T). When an additional copy of TcP5CDH was ectopically introduced into parasites, mutant cells exhibited morphological changes and alterations in TcGP82. O DSF, reported as inhibitor of aldehyde dehydrogenases, interferes with TcP5CDH, as well as exhibited a trypanocidal effect. RNAi silencing assays for TbP5CDH and developmental expression of this enzyme throughout main insect stages within tsetse fly were also addressed. Our data support biochemical relevance of proline-glutamate pathway in T. cruzi, and constitute first evidences regarding occurrence of P5C metabolism over these trypanosomatid species.