No description available.

Loss of physiological function, uncomfortable symptoms and various disease processes are thought to be directly related to the formation of scar tissue following tissue damage. Between ten and thirty percent of patients requiring spinal surgery suffer from failed back surgery syndrome. The pain and instability resulting from failed back syndrome often requires medical treatment and may even require additional surgeries to alleviate its associated symptoms. Following surgery, scar tissue forms that often becomes adherent to the dura and entangled in the ganglia and nerve fibers of the spinal nerves. This scar tissue is considered to play a major role in the development of failed back syndrome. Following tissue injury, excessive oxidative stress and inflammation are considered to be the primary stimulators behind increased fibroblast proliferation and activation, resulting in abundant extracellular matrix deposition. The excessive laying down of extracellular matrix ultimately leads to abundant scar tissue formation. I hypothesized that reducing oxidative stress and inflammation will mitigate scar tissue formation and produce a better outcome after spinal surgeries. Quercetin is a dietary flavonoid with anti-oxidant and anti-inflammatory properties that has been shown to improve the outcome following injury to the spinal cord and reduce the proliferation of fibroblasts. L-2-Oxothiazolidine-4-carboxylate (OTC) also minimizes inflammation and protects against oxidative stress by promoting the synthesis of the potent antioxidant and anti-inflammatory agent glutathione. OTC reduces airway inflammation in asthma models and is potentially capable of modulating extracellular matrix production. <p>Treatment with these two agents was hypothesized to decrease oxidative stress and inflammation, thereby causing an amelioration of scar tissue formation following spinal surgery and improve the outcome. Morphological changes observed initially indicated that improvements in wound healing were occurring in the experimentally treated tissues. In addition, the scar tissue area and the lateral widths of the peridural scar forming between the muscular tissue areas suggested a reduction in the scar size. Although inflammatory cell numbers increased slightly in the experimental treatment groups, particularly during the initial three day post laminectomy time point, this increase was not statistically significant. <p>While quercetin and OTC did not appear to inhibit the influx of inflammatory cells following laminectomy, they did appear to induce a more beneficial wound healing environment. It is possible that these agents are affecting parameters of wound healing not considered by these studies. For instance the myriad of processes mediated by growth factors and cytokines involved in wound healing process may play a much greater role than the inflammatory cells themselves. In conclusion, reducing oxidative stress and inflammation by these agents to ameliorate scar tissue formation following spinal laminectomy was supported by the observed morphology, but not supported by the quantification of inflammatory cells. Additional studies investigating the efficacy of quercetin and OTC on the wound healing process are needed to further understand the role they play in repair and scar tissue formation.

Loss of physiological function, uncomfortable symptoms and various disease processes are thought to be directly related to the formation of scar tissue following tissue damage. Between ten and thirty percent of patients requiring spinal surgery suffer from failed back surgery syndrome. The pain and instability resulting from failed back syndrome often requires medical treatment and may even require additional surgeries to alleviate its associated symptoms. Following surgery, scar tissue forms that often becomes adherent to the dura and entangled in the ganglia and nerve fibers of the spinal nerves. This scar tissue is considered to play a major role in the development of failed back syndrome. Following tissue injury, excessive oxidative stress and inflammation are considered to be the primary stimulators behind increased fibroblast proliferation and activation, resulting in abundant extracellular matrix deposition. The excessive laying down of extracellular matrix ultimately leads to abundant scar tissue formation. I hypothesized that reducing oxidative stress and inflammation will mitigate scar tissue formation and produce a better outcome after spinal surgeries. Quercetin is a dietary flavonoid with anti-oxidant and anti-inflammatory properties that has been shown to improve the outcome following injury to the spinal cord and reduce the proliferation of fibroblasts. L-2-Oxothiazolidine-4-carboxylate (OTC) also minimizes inflammation and protects against oxidative stress by promoting the synthesis of the potent antioxidant and anti-inflammatory agent glutathione. OTC reduces airway inflammation in asthma models and is potentially capable of modulating extracellular matrix production. <p>Treatment with these two agents was hypothesized to decrease oxidative stress and inflammation, thereby causing an amelioration of scar tissue formation following spinal surgery and improve the outcome. Morphological changes observed initially indicated that improvements in wound healing were occurring in the experimentally treated tissues. In addition, the scar tissue area and the lateral widths of the peridural scar forming between the muscular tissue areas suggested a reduction in the scar size. Although inflammatory cell numbers increased slightly in the experimental treatment groups, particularly during the initial three day post laminectomy time point, this increase was not statistically significant. <p>While quercetin and OTC did not appear to inhibit the influx of inflammatory cells following laminectomy, they did appear to induce a more beneficial wound healing environment. It is possible that these agents are affecting parameters of wound healing not considered by these studies. For instance the myriad of processes mediated by growth factors and cytokines involved in wound healing process may play a much greater role than the inflammatory cells themselves. In conclusion, reducing oxidative stress and inflammation by these agents to ameliorate scar tissue formation following spinal laminectomy was supported by the observed morphology, but not supported by the quantification of inflammatory cells. Additional studies investigating the efficacy of quercetin and OTC on the wound healing process are needed to further understand the role they play in repair and scar tissue formation.

Knotenfärbungen mit Abstandsbedingungen sind graphentheoretische Konzepte, motiviert durch das praktische Problem der Frequenzzuweisung in Mobilfunknetzen. In der Arbeit werden verschiedene Varianten solcher Färbungen vorgestellt. Für (Listen-)Färbungen mit einer beliebigen Anzahl r von Abstandsbedingungen werden allgemeine Eigenschaften und Schranken für die benötigte Anzahl von Farben bewiesen. Anschließend wird der Spezialfall r=2 behandelt. Färbungen mit zwei Abstandsbedingungen - die sogenannten L(d,s)-Labellings - werden für eine Reihe von Graphenklassen untersucht, u.a. für reguläre Parkettierungen, Weg- und Kreispotenzen und Graphen mit Durchmesser 2. Die Listenversion dieser Färbungen - die sogenannten L(d,s)-List Labellings - werden für Wege, Sterne, Kreise und Kakteen betrachtet. Ferner werden Untersuchungen zum Zusammenhang von L(2,1)-Labellings und L(2,1)-List Labellings bei speziellen Bäumen durchgeführt.

No description available.

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2015-01-13T11:03:19Z No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Dissertação - Alline Torquato Vasconcelos - 2014.pdf: 3499445 bytes, checksum: 93905607504e61e452d7ce82396c17a9 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2015-01-13T11:04:23Z (GMT) No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Dissertação - Alline Torquato Vasconcelos - 2014.pdf: 3499445 bytes, checksum: 93905607504e61e452d7ce82396c17a9 (MD5) / Made available in DSpace on 2015-01-13T11:04:23Z (GMT). No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Dissertação - Alline Torquato Vasconcelos - 2014.pdf: 3499445 bytes, checksum: 93905607504e61e452d7ce82396c17a9 (MD5) Previous issue date: 2014-06-06 / Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq / Lamivudine (β-L-2',3'-dideoxy-3'-thiacytidine, 3TC) is a nucleoside-based anti-HIV/HBV drug that has provided insights into the nucleic acid double-stranded helix assembly. Two crystal structures thereof assembled with nucleobase pairing and helical stacking as mimicries of DNA, but without the phosphodiester linkages in the fiber periphery, have recently demonstrated that nucleosides bring themselves the chemical information to assemble DNA duplexes even if the covalent backbone is absent. Here, we report the third structural example in which nucleosides are base-paired and helically base-stacked. A DNA-like double stranded helix was prepared cocrystallizing lamivudine with fumaric acid. We have named it as lamivudine duplex III. When substituting maleic acid present in the first example of lamivudine duplex for its trans-stereoisomer, the formation of a DNA-mimicry is still observed but with changes in the crystal stoichiometry, nucleobase pairing pattern and duplex backbone. Lamivudine duplex III exhibits both base pairing motifs present in the antecedent duplexes. In this structure, there are four protonated lamivudine molecules paired in-plane with four neutral ones. These crystallographically independent base pairs are held together through three hydrogen bonds as occurs in lamivudine duplex I made up of cytosine-cytosine+ base pairing only. But, contrarily to the duplex I with pairing between neutral and cationic drug units only, the duplex III has one neutral 3TC=3TC pair in its asymmetric unit. These molecules are kept in contact through only two peripheral N―H•••O hydrogen bonds as in two of the three neutral lamivudine pairs of the second example of lamivudine duplex. In both structures, each neutral pair is face-to-face stacked on top of one another and face-to-tail stacked on bottom of another one. Even in agreement with its higher structural complexity, the duplex III is present with very puckering conformations besides the three different orientations of the OH moiety at C5’. Five-membered oxathiolane ring adopts three envelop puckering modes and two twist conformations. This is the first report of a twist pucker for lamivudine despite of the large number of reported crystal structures thereof. Another remarkable characteristic of the duplex III is in its fiber periphery. There are hydrogen bonds between the 5’-OH moieties of neighbor pairs pointing in the direction of the missing phosphodiester linkages that would covalently bond two adjacent monomers in the strand. Furthermore, the geometry of these interactions reveals the antiparallel orientation of each strand relative to one another into the nucleoside duplex backbone. Noteworthy similarities between the duplexes crystallizing together with either hydrogen maleate or hydrogen fumarate are their left handedness and the outline of surface grooves of similar depth. But, while all hydrogen maleate counterions are lodged on the grooves of the duplex I, some hydrogen fumarate units are also interacting with themselves into one-dimensional chain of counterions. The third example of unusual double-stranded helices of lamivudine strengthens the fact that nucleosides can self-aggregate into DNA-like duplexes even without the covalent phosphodiester linkages in fiber periphery. Besides that, the structure described here adds knowledge on lamivudine versatility to assemble DNA-mimicry in crystals. / A lamivudina (β-L-2',3'-dideoxy-3'-thiacytidine, 3TC) é um fármaco a base de nucleosídeos utilizado para o tratamento de SIDA e Hepatite B. A obtenção de estruturas do tipo dupla hélice de ácidos nucleicos com esse fármaco tem sido alvo de estudo. Recentemente foram reportadas duas estruturas cristalinas mimetizando DNA, formadas por pares de nucleosídeos empacotados em uma dupla hélice, mas sem ligações fosfodiéster na periferia da cadeia. Estas estruturas demonstraram que os nucleosídeos possuem informação química suficiente para a formação de estruturas dessa natureza mesmo com a ausência das ligações covalentes fosfodiéster. Neste trabalho um terceiro exemplo de uma estrutura contendo bases de nuclosídeos pareadas e sobrepostas helicoidalmente, mimetizando DNA, é reportado. Essa modificação cristalina foi preparada através da cocristalização da lamivudina com o ácido fumárico e a estrutura obtida foi denominada duplex III. Com a substituição do ácido maleico, presente no primeiro exemplo de dupla hélice de lamivudina, pelo seu estéreoisômero trans, o ácido fumárico, a formação de uma estrutura mimetizando o DNA também foi observada, porém, com diferenças na estequiometria do cristal, nos padrões de interação do pareamento das bases, assim como no esqueleto da dupla hélice. O pareamento das bases na duplex III de lamivudina possui padrões de interação semelhante a ambas estruturas precedentes. Na duplex III existem quatro pares parcialmente protonados, onde uma lamivudina protonada está pareada com outra neutra. Esse tipo de pareamento se dá através de três ligações de hidrogênio e é semelhante ao pareamento presente na estrutura da duplex I de lamivudina composto apenas por pares do tipo 3TC+≡3TC. Diferentemente da duplex I que possui exclusivamente pares parcialmente protonados, a duplex III possui também um par neutro do tipo 3TC=3TC na sua unidade assimétrica. O pareamento dessas bases é formado apenas por duas ligações de hidrogênio do tipo N―H•••O, semelhante a dois dos três pares neutros que constituem a duplex II de lamivudina. O empacotamento dos pares neutros na duplex III é semelhante ao da duplex II, cada par neutro empacota com uma padrão face a face com o par que o antecede e face a cauda com o par subsequente. Devido à grande complexidade estrutural da duplex III, temos uma maior variação nas conformações assumidas tanto pelo anel oxatiolano quanto pelo fragmento citosinico, assim como nas três orientações adotadas pelo grupo hidroxílico ligado ao carbono C5’. O anel oxatiolano de cinco membros, adota três diferentes conformações do tipo envelope e duas conformações do tipo cambaleante. Apesar de essas serem as primeiras estruturas reportadas com conformações do tipo cambaleante para a lamivudina, esse tipo de conformação é comum para várias outras estruturas cristalinas. Outra característica que merece destaque na estrutura obtida da duplex III está nos padrões de interação presentes na periferia da dupla hélice. Nota-se a presença de ligações de hidrogênio entre os grupos 5’-OH de pares vizinhos, que ocorrem na direção onde as ligações fosfodiéster deveriam existir entre dois monômeros adjacentes. Além disso, a geometria dessas ligações de hidrogênio revelam uma orientação antiparalela de uma fita em relação a outra no esqueleto da duplex. Existem algumas semelhanças notáveis entre as duplexes I e III, cristalizadas com hidrogenomaleato e hidrogenofumarato, como a espiralização a esquerda e o fato de ambas não possuírem diferença entre sulcos principais e secundários, uma vez que todos os sulcos ao longo da cadeia possuem dimensões semelhantes. Porém, todos os contraíons estão acomodados nos sulcos da duplex I, enquanto que na duplex III alguns contraíons interagem entre si formando uma cadeia unidimensional de contraíons. Esse terceiro exemplo de uma estrutura atípica de dupla hélice de lamivudina reforça o fato de que nucleosídeos podem se agregar em estruturas semelhantes a dupla hélice do DNA, mesmo com a ausência das ligações covalentes fosfodiéster. Além disso a estrutura da duplex III adiciona conhecimento quanto a versatilidade da lamivudina em formar estruturas mimetizando DNA em cristais.

As acidemias D-2-hidroxiglutárica e L-2-hidroxiglutárica são duas distintas desordens neurometabólicas bioquimicamente caracterizadas por níveis aumentados dos ácidos D-2-hidroxiglutárico e L-2-hidroxiglutárico em tecidos e fluidos biológicos, respectivamente. Pacientes acometidos pela acidemia D-2-hidroxiglutárica são classificados em duas variantes, a D-2-hidroxiglutárica do tipo I ou a D-2-hidroxiglutárica do tipo II. A acidemia D-2-hidroxiglutárica do tipo I é causada por uma mutação no gene da D-2-hidroxiglutarato desidrogenase enquanto que a acidemia D-2-hidroxiglutárica do tipo II é causada por uma mutação de ganho de função no gene da isocitrato desidrogenase II. A acidemia L-2-hidroxiglutárica é causada por uma mutação no gene da L-2-hidroxiglutarato desidrogenase. Considerando que a fisiopatologia destas doenças não está totalmente elucidada e que muitos estudos têm demonstrado o envolvimento do estresse oxidativo em erros inatos do metabolismo, este trabalho tem por objetivo principal investigar parâmetros de estresse oxidativo e nitrativo na urina de pacientes com acidemia L-2-hidroxiglutárica e o dano ao DNA in vitro causado pelos ácidos acumulados em ambas as patologias, as acidemias D-2-hidroxiglutárica e L-2-hidroxiglutárica, bem como o efeito protetor da L-carnitina sobre o dano. Dessa forma, verificou-se que as concentrações de 50 μM do ácido D-2-hidroxiglutárico e 30 μM do ácido L-2-hidroxiglutárico induzem dano ao DNA e que concentrações de 30 μM e 150 μM de L-carnitina reduzem significativamente in vitro o dano ao DNA, comparado aos controles. Além disso, foram analisadas amostras de urina dos pacientes com acidemia L-2-hidroxiglutárica. Observou-se aumento significativo de espécies de guanina oxidadas, um marcador bioquímico de dano oxidativo ao DNA, bem como um aumento significativo da excreção de di-tirosina, indicando que os pacientes tem dano a proteínas. Entretanto, não houve diferença significativa nos níveis de isoprostanos urinários e nos níveis de espécies reativas do nitrogênio. Esses resultados sugerem, pelo menos em parte, dano oxidativo a proteínas e ao DNA e ressaltam o potencial antioxidante da L-carnitina como um promissor adjuvante no tratamento de pacientes afetados pelas acidemias L-2-hidroxiglutárica ou D-2-hidroxiglutárica. / D-2-hydroxyglutaric and L-2-hydroxyglutaric acidurias are two distinct neurometabolic disorders biochemically characterized by increased levels of D-2-hydroxyglutaric and L-2-hydroxyglutaric acids in biological fluids and tissues, respectively. Patients affected by D-2-hydroxyglutaric aciduria are classified into two variants, D-2-hydroxyglutaric aciduria type I or D-2-hydroxyglutaric aciduria type II. D-2-hydroxyglutaric aciduria type I is caused by mutation of D-2-hydroxyglutarate dehydrogenase gene while D-2-hydroxyglutaric aciduria type II is caused by a gain of function mutation in isocitrate dehydrogenase 2 gene. L-2-hydroxyglutaric aciduria is caused by mutation in the L-2-hydroxyglutarate dehydrogenase gene. Considering that the pathophysiology of these diseases is not fully understood and that many studies have been shown the involvement of oxidative stress in inborn errors of metabolism, the main objective of this work was investigate oxidative and nitrative stress parameters in the urine of L-2-hydroxyglutaric aciduria patients and to investigate the in vitro DNA damage caused by the accumulated acids of D-2-hydroxyglutaric and L-2-hydroxyglutaric acidurias as well as the protective effect of L-carnitine on this damage. It has been found that concentrations of 50 μM of D-2-hydroxyglutaric acid and 30 μM of L-2-hydroxyglutaric acid induce DNA damage and concentrations of 30 μM and 150 μM of L-carnitine significantly reduced the in vitro DNA damage compared to controls. In addition, urine samples from L-2-hydroxyglutaric aciduria patients were analyzed. It was observed a significant increase of oxidized guanine species, an oxidative DNA damage biomarker as well as a significant increase of urinary di-tyrosine level, indicating protein oxidative damage in the patients. However, there was no significant difference in the levels of urinary isoprostanes and reactive nitrogen species. These results suggest, at least in part, proteins and DNA oxidative damage and highlight the L-carnitine antioxidant potential as a promising adjuvant in the treatment of patients affected by L-2-hydroxyglutaric or D-2-hydroxyglutaric aciduria.

As acidemias D-2-hidroxiglutárica e L-2-hidroxiglutárica são duas distintas desordens neurometabólicas bioquimicamente caracterizadas por níveis aumentados dos ácidos D-2-hidroxiglutárico e L-2-hidroxiglutárico em tecidos e fluidos biológicos, respectivamente. Pacientes acometidos pela acidemia D-2-hidroxiglutárica são classificados em duas variantes, a D-2-hidroxiglutárica do tipo I ou a D-2-hidroxiglutárica do tipo II. A acidemia D-2-hidroxiglutárica do tipo I é causada por uma mutação no gene da D-2-hidroxiglutarato desidrogenase enquanto que a acidemia D-2-hidroxiglutárica do tipo II é causada por uma mutação de ganho de função no gene da isocitrato desidrogenase II. A acidemia L-2-hidroxiglutárica é causada por uma mutação no gene da L-2-hidroxiglutarato desidrogenase. Considerando que a fisiopatologia destas doenças não está totalmente elucidada e que muitos estudos têm demonstrado o envolvimento do estresse oxidativo em erros inatos do metabolismo, este trabalho tem por objetivo principal investigar parâmetros de estresse oxidativo e nitrativo na urina de pacientes com acidemia L-2-hidroxiglutárica e o dano ao DNA in vitro causado pelos ácidos acumulados em ambas as patologias, as acidemias D-2-hidroxiglutárica e L-2-hidroxiglutárica, bem como o efeito protetor da L-carnitina sobre o dano. Dessa forma, verificou-se que as concentrações de 50 μM do ácido D-2-hidroxiglutárico e 30 μM do ácido L-2-hidroxiglutárico induzem dano ao DNA e que concentrações de 30 μM e 150 μM de L-carnitina reduzem significativamente in vitro o dano ao DNA, comparado aos controles. Além disso, foram analisadas amostras de urina dos pacientes com acidemia L-2-hidroxiglutárica. Observou-se aumento significativo de espécies de guanina oxidadas, um marcador bioquímico de dano oxidativo ao DNA, bem como um aumento significativo da excreção de di-tirosina, indicando que os pacientes tem dano a proteínas. Entretanto, não houve diferença significativa nos níveis de isoprostanos urinários e nos níveis de espécies reativas do nitrogênio. Esses resultados sugerem, pelo menos em parte, dano oxidativo a proteínas e ao DNA e ressaltam o potencial antioxidante da L-carnitina como um promissor adjuvante no tratamento de pacientes afetados pelas acidemias L-2-hidroxiglutárica ou D-2-hidroxiglutárica. / D-2-hydroxyglutaric and L-2-hydroxyglutaric acidurias are two distinct neurometabolic disorders biochemically characterized by increased levels of D-2-hydroxyglutaric and L-2-hydroxyglutaric acids in biological fluids and tissues, respectively. Patients affected by D-2-hydroxyglutaric aciduria are classified into two variants, D-2-hydroxyglutaric aciduria type I or D-2-hydroxyglutaric aciduria type II. D-2-hydroxyglutaric aciduria type I is caused by mutation of D-2-hydroxyglutarate dehydrogenase gene while D-2-hydroxyglutaric aciduria type II is caused by a gain of function mutation in isocitrate dehydrogenase 2 gene. L-2-hydroxyglutaric aciduria is caused by mutation in the L-2-hydroxyglutarate dehydrogenase gene. Considering that the pathophysiology of these diseases is not fully understood and that many studies have been shown the involvement of oxidative stress in inborn errors of metabolism, the main objective of this work was investigate oxidative and nitrative stress parameters in the urine of L-2-hydroxyglutaric aciduria patients and to investigate the in vitro DNA damage caused by the accumulated acids of D-2-hydroxyglutaric and L-2-hydroxyglutaric acidurias as well as the protective effect of L-carnitine on this damage. It has been found that concentrations of 50 μM of D-2-hydroxyglutaric acid and 30 μM of L-2-hydroxyglutaric acid induce DNA damage and concentrations of 30 μM and 150 μM of L-carnitine significantly reduced the in vitro DNA damage compared to controls. In addition, urine samples from L-2-hydroxyglutaric aciduria patients were analyzed. It was observed a significant increase of oxidized guanine species, an oxidative DNA damage biomarker as well as a significant increase of urinary di-tyrosine level, indicating protein oxidative damage in the patients. However, there was no significant difference in the levels of urinary isoprostanes and reactive nitrogen species. These results suggest, at least in part, proteins and DNA oxidative damage and highlight the L-carnitine antioxidant potential as a promising adjuvant in the treatment of patients affected by L-2-hydroxyglutaric or D-2-hydroxyglutaric aciduria.

As acidemias D-2-hidroxiglutárica e L-2-hidroxiglutárica são duas distintas desordens neurometabólicas bioquimicamente caracterizadas por níveis aumentados dos ácidos D-2-hidroxiglutárico e L-2-hidroxiglutárico em tecidos e fluidos biológicos, respectivamente. Pacientes acometidos pela acidemia D-2-hidroxiglutárica são classificados em duas variantes, a D-2-hidroxiglutárica do tipo I ou a D-2-hidroxiglutárica do tipo II. A acidemia D-2-hidroxiglutárica do tipo I é causada por uma mutação no gene da D-2-hidroxiglutarato desidrogenase enquanto que a acidemia D-2-hidroxiglutárica do tipo II é causada por uma mutação de ganho de função no gene da isocitrato desidrogenase II. A acidemia L-2-hidroxiglutárica é causada por uma mutação no gene da L-2-hidroxiglutarato desidrogenase. Considerando que a fisiopatologia destas doenças não está totalmente elucidada e que muitos estudos têm demonstrado o envolvimento do estresse oxidativo em erros inatos do metabolismo, este trabalho tem por objetivo principal investigar parâmetros de estresse oxidativo e nitrativo na urina de pacientes com acidemia L-2-hidroxiglutárica e o dano ao DNA in vitro causado pelos ácidos acumulados em ambas as patologias, as acidemias D-2-hidroxiglutárica e L-2-hidroxiglutárica, bem como o efeito protetor da L-carnitina sobre o dano. Dessa forma, verificou-se que as concentrações de 50 μM do ácido D-2-hidroxiglutárico e 30 μM do ácido L-2-hidroxiglutárico induzem dano ao DNA e que concentrações de 30 μM e 150 μM de L-carnitina reduzem significativamente in vitro o dano ao DNA, comparado aos controles. Além disso, foram analisadas amostras de urina dos pacientes com acidemia L-2-hidroxiglutárica. Observou-se aumento significativo de espécies de guanina oxidadas, um marcador bioquímico de dano oxidativo ao DNA, bem como um aumento significativo da excreção de di-tirosina, indicando que os pacientes tem dano a proteínas. Entretanto, não houve diferença significativa nos níveis de isoprostanos urinários e nos níveis de espécies reativas do nitrogênio. Esses resultados sugerem, pelo menos em parte, dano oxidativo a proteínas e ao DNA e ressaltam o potencial antioxidante da L-carnitina como um promissor adjuvante no tratamento de pacientes afetados pelas acidemias L-2-hidroxiglutárica ou D-2-hidroxiglutárica. / D-2-hydroxyglutaric and L-2-hydroxyglutaric acidurias are two distinct neurometabolic disorders biochemically characterized by increased levels of D-2-hydroxyglutaric and L-2-hydroxyglutaric acids in biological fluids and tissues, respectively. Patients affected by D-2-hydroxyglutaric aciduria are classified into two variants, D-2-hydroxyglutaric aciduria type I or D-2-hydroxyglutaric aciduria type II. D-2-hydroxyglutaric aciduria type I is caused by mutation of D-2-hydroxyglutarate dehydrogenase gene while D-2-hydroxyglutaric aciduria type II is caused by a gain of function mutation in isocitrate dehydrogenase 2 gene. L-2-hydroxyglutaric aciduria is caused by mutation in the L-2-hydroxyglutarate dehydrogenase gene. Considering that the pathophysiology of these diseases is not fully understood and that many studies have been shown the involvement of oxidative stress in inborn errors of metabolism, the main objective of this work was investigate oxidative and nitrative stress parameters in the urine of L-2-hydroxyglutaric aciduria patients and to investigate the in vitro DNA damage caused by the accumulated acids of D-2-hydroxyglutaric and L-2-hydroxyglutaric acidurias as well as the protective effect of L-carnitine on this damage. It has been found that concentrations of 50 μM of D-2-hydroxyglutaric acid and 30 μM of L-2-hydroxyglutaric acid induce DNA damage and concentrations of 30 μM and 150 μM of L-carnitine significantly reduced the in vitro DNA damage compared to controls. In addition, urine samples from L-2-hydroxyglutaric aciduria patients were analyzed. It was observed a significant increase of oxidized guanine species, an oxidative DNA damage biomarker as well as a significant increase of urinary di-tyrosine level, indicating protein oxidative damage in the patients. However, there was no significant difference in the levels of urinary isoprostanes and reactive nitrogen species. These results suggest, at least in part, proteins and DNA oxidative damage and highlight the L-carnitine antioxidant potential as a promising adjuvant in the treatment of patients affected by L-2-hydroxyglutaric or D-2-hydroxyglutaric aciduria.

No description available.