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Due to a typesetting error the wrong Table 2 was used. The correct Table 2 is shown here.
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OBJECTIVES: To describe the spectrum of movement disorders and cerebrospinal fluid (CSF) neurotransmitter profiles in paediatric patients with POLG disease. METHODS: We identified children with genetically confirmed POLG disease, in whom CSF neurotransmitter analysis had been undertaken. Clinical data were collected retrospectively. CSF neurotransmitter levels were compared to both standardised age-related reference ranges and to non-POLG patients presenting with status epilepticus. RESULTS: Forty-one patients with POLG disease were identified. Almost 50% of the patients had documented evidence of a movement disorder, including non-epileptic myoclonus, choreoathetosis and ataxia. CSF neurotransmitter analysis was undertaken in 15 cases and abnormalities were seen in the majority (87%) of cases tested. In many patients, distinctive patterns were evident, including raised neopterin, homovanillic acid and 5-hydroxyindoleacetic acid levels. CONCLUSIONS: Children with POLG mutations can manifest with a wide spectrum of abnormal movements, which are often prominent features of the clinical syndrome. Underlying pathophysiology is probably multifactorial, and aberrant monoamine metabolism is likely to play a role.
Assuntos
Doenças Mitocondriais/líquido cefalorraquidiano , Transtornos dos Movimentos/etiologia , Neurotransmissores/líquido cefalorraquidiano , Adolescente , Criança , Pré-Escolar , DNA Polimerase gama/genética , Feminino , Ácido Homovanílico/líquido cefalorraquidiano , Humanos , Ácido Hidroxi-Indolacético/líquido cefalorraquidiano , Lactente , Masculino , Doenças Mitocondriais/genética , Mutação , Neopterina/líquido cefalorraquidiano , Estudos RetrospectivosRESUMO
Childhood neurotransmitter disorders are increasingly recognised as an expanding group of inherited neurometabolic syndromes. They are caused by disturbance in synthesis, metabolism, and homeostasis of the monoamine neurotransmitters, including the catecholamines (dopamine, norepinephrine, and epinephrine) and serotonin. Disturbances in monoamine neurotransmission will lead to neurological symptoms that often overlap with clinical features of other childhood neurological disorders (such as hypoxic ischaemic encephalopathy, cerebral palsy, other movement disorders, and paroxysmal conditions); consequently, neurotransmitter disorders are frequently misdiagnosed. The diagnosis of neurotransmitter disorders is made through detailed clinical assessment, analysis of cerebrospinal fluid neurotransmitters, and further supportive diagnostic investigations. Early and accurate diagnosis of neurotransmitter disorders is important, as many are amenable to therapeutic intervention. The principles of treatment for monoamine neurotransmitter disorders are mainly directly derived from understanding these metabolic pathways. In disorders characterized by enzyme deficiency, we aim to increase monoamine substrate availability, boost enzyme co-factor levels, reduce monoamine breakdown, and replace depleted levels of monoamines with pharmacological analogs as clinically indicated. Most monoamine neurotransmitter disorders lead to reduced levels of central dopamine and/or serotonin. Complete amelioration of motor symptoms is achievable in some disorders, such as Segawa's syndrome, and, in other conditions, significant improvement in quality of life can be attained with pharmacotherapy. In this review, we provide an overview of the clinical features and current treatment strategies for childhood monoamine neurotransmitter disorders.
Assuntos
Catecolaminas/metabolismo , Doenças do Sistema Nervoso/tratamento farmacológico , Neurotransmissores/metabolismo , Serotonina/metabolismo , Criança , Dopamina/metabolismo , Ácido Fólico/fisiologia , Humanos , Doenças do Sistema Nervoso/diagnóstico , Doenças do Sistema Nervoso/metabolismo , Fenilcetonúrias/tratamento farmacológicoRESUMO
Primary Coenzyme Q10 (CoQ10) deficiency is an autosomal recessive disorder with a heterogeneous clinical presentation. Common presenting features include both muscle and neurological dysfunction. Muscle abnormalities can improve, both clinically and biochemically following CoQ10 supplementation, however neurological symptoms are only partially ameliorated. At present, the reasons for the refractory nature of the neurological dysfunction remain unknown. In order to investigate this at the biochemical level we evaluated the effect of CoQ10 treatment upon a previously established neuronal cell model of CoQ10 deficiency. This model was established by treatment of human SH-SY5Y neuronal cells with 1 mM para-aminobenzoic acid (PABA) which induced a 54% decrease in cellular CoQ10 status. CoQ10 treatment (2.5 µM) for 5 days significantly (p<0.0005) decreased the level of mitochondrial superoxide in the CoQ10 deficient neurons. In addition, CoQ10 treatment (5 µM) restored mitochondrial membrane potential to 90% of the control level. However, CoQ10 treatment (10 µM) was only partially effective at restoring mitochondrial electron transport chain (ETC) enzyme activities. ETC complexes II/III activity was significantly (p<0.05) increased to 82.5% of control levels. ETC complexes I and IV activities were restored to 71.1% and 77.7%, respectively of control levels. In conclusion, the results of this study have indicated that although mitochondrial oxidative stress can be attenuated in CoQ10 deficient neurons following CoQ10 supplementation, ETC enzyme activities appear partially refractory to treatment. Accordingly, treatment with >10 µM CoQ10 may be required to restore ETC enzyme activities to control level. Accordingly, these results have important implication for the treatment of the neurological presentations of CoQ10 deficiency and indicate that high doses of CoQ10 may be required to elicit therapeutic efficacy.
Assuntos
Ataxia/tratamento farmacológico , Ataxia/metabolismo , Mitocôndrias/efeitos dos fármacos , Doenças Mitocondriais/tratamento farmacológico , Doenças Mitocondriais/metabolismo , Debilidade Muscular/tratamento farmacológico , Debilidade Muscular/metabolismo , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Ubiquinona/deficiência , Linhagem Celular Tumoral , DNA Mitocondrial/metabolismo , Suplementos Nutricionais , Transporte de Elétrons/efeitos dos fármacos , Metabolismo Energético/efeitos dos fármacos , Humanos , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Mitocôndrias/enzimologia , Mitocôndrias/metabolismo , Neuroblastoma , Espécies Reativas de Oxigênio/metabolismo , Ubiquinona/metabolismoRESUMO
Mitochondrial diseases are an unusually genetically and phenotypically heterogeneous group of disorders, which are extremely challenging to treat. Currently, apart from supportive therapy, there are no effective treatments for the vast majority of mitochondrial diseases. Huge scientific effort, however, is being put into understanding the mechanisms underlying mitochondrial disease pathology and developing potential treatments. To date, a variety of treatments have been evaluated by randomized clinical trials, but unfortunately, none of these has delivered breakthrough results. Increased understanding of mitochondrial pathways and the development of many animal models, some of which are accurate phenocopies of human diseases, are facilitating the discovery and evaluation of novel prospective treatments. Targeting reactive oxygen species has been a treatment of interest for many years; however, only in recent years has it been possible to direct antioxidant delivery specifically into the mitochondria. Increasing mitochondrial biogenesis, whether by pharmacological approaches, dietary manipulation or exercise therapy, is also currently an active area of research. Modulating mitochondrial dynamics and mitophagy and the mitochondrial membrane lipid milieu have also emerged as possible treatment strategies. Recent technological advances in gene therapy, including allotopic and transkingdom gene expression and mitochondrially targeted transcription activator-like nucleases, have led to promising results in cell and animal models of mitochondrial diseases, but most of these techniques are still far from clinical application.
Assuntos
Antioxidantes/farmacologia , Antioxidantes/uso terapêutico , Mitocôndrias/efeitos dos fármacos , Doenças Mitocondriais/tratamento farmacológico , Terapia de Alvo Molecular/métodos , Animais , Ensaios Clínicos como Assunto , Modelos Animais de Doenças , Metabolismo Energético/efeitos dos fármacos , Terapia Genética/métodos , Humanos , Mitocôndrias/metabolismo , Doenças Mitocondriais/terapia , Renovação Mitocondrial/efeitos dos fármacos , Modelos Biológicos , Fosforilação Oxidativa/efeitos dos fármacosRESUMO
AIM: Tandem mass spectrometry (MS/MS) is a recommended investigation for sudden unexpected death in infancy (SUDI), but there are limited data regarding yield and potential influencing factors. This study investigates postmortem acylcarnitine profiles in a large cohort of infant deaths from a single centre, including those with metabolic disease. METHODS: Acylcarnitine results obtained by MS/MS from routine blood/bile spot samples during the standard autopsy investigation were identified from infant deaths over a 14-year period. Results were categorised as normal or abnormal according to the clinical report by a specialist paediatric biochemist. Possible interdependent variables were assessed, multiple linear regression models were constructed and residual comparison was undertaken. RESULTS: 397 blood and 268 bile MS/MS results were identified from infant cases, including 255 matched blood-bile pairs. There was significant association between blood acylcarnitine findings and postmortem interval (PMI), body mass index and liver weight. A probable cause of death was identified in 40% of sudden death cases, including 18 (2%) with a definite or highly likely cause of death as underlying metabolic disease; this represented 12 (12%) unexpected deaths in the first week of life and six (<1%) aged 7-365 days. Fatty acid oxidation disorders identified included very long chain acyl-CoA dehydrogenase deficiency, medium chain acyl-CoA dehydrogenase deficiency and carnitine transporter defects. CONCLUSION: Postmortem blood and bile acylcarnitine profiles are influenced by several variables, and PMI can influence MS/MS acylcarnitine results. Metabolic disease may present as SUDI and may be identified from postmortem samples.
Assuntos
Autopsia/métodos , Doenças Metabólicas/patologia , Mudanças Depois da Morte , Morte Súbita do Lactente/patologia , Bile/química , Carnitina/análogos & derivados , Carnitina/metabolismo , Humanos , Lactente , Recém-Nascido , Fígado/patologia , Doenças Metabólicas/sangue , Tamanho do Órgão , Espectrometria de Massas em TandemRESUMO
OBJECTIVE: To describe the current treatment; clinical, biochemical, and molecular findings; and clinical follow-up of patients with aromatic l-amino acid decarboxylase (AADC) deficiency. METHOD: Clinical and biochemical data of 78 patients with AADC deficiency were tabulated in a database of pediatric neurotransmitter disorders (JAKE). A total of 46 patients have been previously reported; 32 patients are described for the first time. RESULTS: In 96% of AADC-deficient patients, symptoms (hypotonia 95%, oculogyric crises 86%, and developmental retardation 63%) became clinically evident during infancy or childhood. Laboratory diagnosis is based on typical CSF markers (low homovanillic acid, 5-hydroxyindoleacidic acid, and 3-methoxy-4-hydroxyphenolglycole, and elevated 3-O-methyl-l-dopa, l-dopa, and 5-hydroxytryptophan), absent plasma AADC activity, or elevated urinary vanillactic acid. A total of 24 mutations in the DDC gene were detected in 49 patients (8 reported for the first time: p.L38P, p.Y79C, p.A110Q, p.G123R, p.I42fs, c.876G>A, p.R412W, p.I433fs) with IVS6+ 4A>T being the most common one (allele frequency 45%). CONCLUSION: Based on clinical symptoms, CSF neurotransmitters profile is highly indicative for the diagnosis of aromatic l-amino acid decarboxylase deficiency. Treatment options are limited, in many cases not beneficial, and prognosis is uncertain. Only 15 patients with a relatively mild form clearly improved on a combined therapy with pyridoxine (B6)/pyridoxal phosphate, dopamine agonists, and monoamine oxidase B inhibitors.
Assuntos
Descarboxilases de Aminoácido-L-Aromático/líquido cefalorraquidiano , Descarboxilases de Aminoácido-L-Aromático/deficiência , Adolescente , Biomarcadores/líquido cefalorraquidiano , Criança , Pré-Escolar , Seguimentos , Humanos , Lactente , Neurotransmissores/líquido cefalorraquidiano , Neurotransmissores/deficiência , Adulto JovemRESUMO
We recently reported insulin resistance in adult offspring of obese C57BL/6J mice. We have now evaluated whether parameters of skeletal muscle structure and function may play a role in insulin resistance in this model of developmental programming. Obesity was induced in female mice by feeding a highly palatable sugar and fat-rich diet for 6 wk prior to pregnancy, and during pregnancy and lactation. Offspring of obese dams were weaned onto standard laboratory chow. At 3 mo of age, skeletal muscle insulin signaling protein expression, mitochondrial electron transport chain activity (ETC), muscle fiber type, fiber density, and fiber cross-sectional area were compared with that of offspring of control dams weaned onto the chow diet. Female offspring of obese dams demonstrated decreased skeletal muscle expression of p110beta, the catalytic subunit of PI3K (P < 0.01), as well as reduced Akt phosphorylation at Serine residue 473 compared with control offspring. Male offspring of obese dams demonstrated increased skeletal muscle Akt2 and PKCzeta expression (P < 0.01; P < 0.001, respectively). A decrease in mitochondrial-linked complex II-III was observed in male offspring of obese dams (P < 0.01), which was unrelated to CoQ deficiency. This was not observed in females. There were no differences in muscle fiber density between offspring of obese dams and control offspring in either sex. Sex-related alterations in key insulin-signaling proteins and in mitochondrial ETC may contribute to a state of insulin resistance in offspring of obese mice.
Assuntos
Complexo III da Cadeia de Transporte de Elétrons/metabolismo , Complexo II de Transporte de Elétrons/metabolismo , Resistência à Insulina , Insulina/metabolismo , Mitocôndrias Musculares/metabolismo , Obesidade/metabolismo , Músculo Quadríceps/metabolismo , Transdução de Sinais , Fenômenos Fisiológicos da Nutrição Animal , Animais , Peso Corporal , Classe I de Fosfatidilinositol 3-Quinases , Modelos Animais de Doenças , Feminino , Transportador de Glucose Tipo 4/metabolismo , Proteínas Substratos do Receptor de Insulina/metabolismo , Masculino , Fenômenos Fisiológicos da Nutrição Materna , Camundongos , Camundongos Endogâmicos C57BL , Mitocôndrias Musculares/enzimologia , Fibras Musculares Esqueléticas/metabolismo , Obesidade/patologia , Obesidade/fisiopatologia , Fosfatidilinositol 3-Quinases/metabolismo , Fosforilação , Gravidez , Efeitos Tardios da Exposição Pré-Natal , Proteína Quinase C/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Músculo Quadríceps/enzimologia , Músculo Quadríceps/patologia , Receptor de Insulina/metabolismo , Fatores Sexuais , Ubiquinona/metabolismoRESUMO
The pathogenesis of mitochondrial disorders has largely focused on the impairment of cellular energy metabolism. However, mitochondrial dysfunction has also been implicated as a factor in the initiation of apoptosis due to the translocation of cytochrome c, from mitochondria to the cytosol, and the subsequent cleavage of pro-caspase 3. In this study, we determined the cytochrome c content of cytosols (skeletal muscle) prepared from 22 patients with evidence of compromised mitochondrial electron transport chain enzyme activity and 26 disease controls. The cytochrome c content of the mitochondrial electron transport chain-deficient group was found to be significantly (p < 0.02) elevated when compared with the control group (63.7 +/- 15.5 versus 27.7 +/- 2.5 ng/mg protein). Furthermore, a relationship between the cytosolic cytochrome c content of skeletal muscle and complex I and complex IV activities was demonstrated. Such data raise the possibility that mitochondrial cytochrome c release may be a feature of mitochondrial disorders, particularly for those patients with marked deficiencies of respiratory chain enzymes. Whether initiation of apoptosis occurs as a direct consequence of this cytochrome c release has not been fully evaluated here. However, for one patient with the greatest documented cytosolic cytochrome c content, caspase 3 could be demonstrated in the cytosolic preparation. Further work is required in order to establish whether a relationship also exists between caspase 3 formation and the magnitude of respiratory chain deficiency.
Assuntos
Citocromos c/metabolismo , Mitocôndrias/enzimologia , Doenças Mitocondriais/enzimologia , Adolescente , Adulto , Caspase 3/metabolismo , Criança , Pré-Escolar , Citrato (si)-Sintase/metabolismo , Citosol/enzimologia , Transporte de Elétrons/fisiologia , Humanos , Indicadores e Reagentes , Lactente , Recém-Nascido , Pessoa de Meia-Idade , Proteínas Mitocondriais/metabolismo , Músculo Esquelético/enzimologia , Adulto JovemRESUMO
Assessment of total neopterin and tetrahydrobioterin (BH4) concentrations in cerebrospinal fluid (CSF) can be used to identify potential disorders of BH4 biosynthesis. In this study, we demonstrate that exposure of CSF to nitric oxide leads to an accelerated degradation of BH4 but does not affect the total neopterin concentration. These data suggest that in those conditions associated with increased nitric oxide formation, perturbation of the total neopterin to BH4 ratio could occur. Under such circumstances a putative diagnosis of a defect in BH4 biosynthesis may erroneously be proposed. Assessment of central nitric oxide generation may therefore be a useful adjunct to the determination of CSF pterin status.
Assuntos
Biopterinas/análogos & derivados , Líquido Cefalorraquidiano/efeitos dos fármacos , Neopterina/metabolismo , Óxido Nítrico/farmacologia , Biopterinas/metabolismo , Líquido Cefalorraquidiano/metabolismo , HumanosRESUMO
Mitochondrial encephalomyopathies, arising from deficiencies of the electron transport chain (ETC) give rise to a wide clinical spectrum of presentation and are often progressive in nature. The aetiology of mitochondrial encephalomyopathies have yet to be fully elucidated, however, a successive loss of ETC function may contribute to the progressive nature of these disorders. The possibility arises that as a consequence of a primary impairment of ETC activity, secondary damage to the ETC may occur. In order to investigate this hypothesis, we established a model of cytochrome oxidase (Complex IV) deficiency in cultured human astrocytoma 1321N cells. Potassium cyanide (KCN, 1mM) resulted in a sustained 50% (p<0.01) loss of complex IV. At 24h activities of the other ETC complexes were unaffected. However, at 72h significant loss of succinate-cytochrome c reductase (complex II-III) activity expressed as a ratio to the mitochondrial marker, citrate synthase was observed. (KCN treated; 0.065+/-0.011 vs controls; 0.118+/-0.017 mean+/-SEM, n=8, p<0.05). These results provide a possible mechanism for the progressive nature of ETC defects and why in some patients multiple patterns of ETC deficiencies can be demonstrated.
Assuntos
Complexo III da Cadeia de Transporte de Elétrons/metabolismo , Complexo II de Transporte de Elétrons/metabolismo , Complexo IV da Cadeia de Transporte de Elétrons/antagonistas & inibidores , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Encefalomiopatias Mitocondriais/enzimologia , Encefalomiopatias Mitocondriais/patologia , Astrocitoma/metabolismo , Linhagem Celular , Citrato (si)-Sintase/metabolismo , Coenzimas/metabolismo , Glutationa/metabolismo , Humanos , Encefalomiopatias Mitocondriais/terapia , Cloreto de Potássio/farmacologia , Ligação Proteica , Ubiquinona/análogos & derivados , Ubiquinona/metabolismoRESUMO
Tetrahydrobiopterin (BH4) is an essential cofactor for all isoforms of nitric oxide synthase. While it is well established that BH4 deficiency states are associated with impairment of dopamine, serotonin and phenylalanine metabolism, less is known with regard to the effects of deficiency of the cofactor upon nitric oxide (NO) metabolism. In this study, we have evaluated the effects of partial BH4 deficiency upon (a) tissue availability of the antioxidant glutathione, (b) basal NO production and (c) NO generation following exposure to lipopolysaccharide (LPS), which is known to increase expression of the inducible form of nitric oxide synthase. Using the hph-1 mouse, which displays a partial BH4 deficiency owing to impaired activity of GTP cyclohydrolase, we report decreased levels of glutathione in brain and kidney and evidence for decreased basal generation of nitric oxide in the periphery (as judged by the plasma nitrate plus nitrite concentration). Following LPS administration, peripheral NO generation increases. However, the concentration of plasma nitrate plus nitrite achieved was significantly decreased in the hph-1 mouse. Furthermore, LPS administration caused loss of glutathione in both wild-type and hph-1 liver and kidney. It is concluded that cofactor replacement, sufficient to fully correct a cellular BH4 deficiency, may be of benefit to patients with inborn errors of BH4 metabolism.
Assuntos
Biopterinas/análogos & derivados , Proteínas de Transporte/genética , GTP Cicloidrolase/deficiência , Glutationa/metabolismo , Mutação , Óxido Nítrico/metabolismo , Animais , Disponibilidade Biológica , Biopterinas/deficiência , Biopterinas/metabolismo , Encéfalo/metabolismo , Rim/metabolismo , Lipopolissacarídeos/farmacologia , Fígado/metabolismo , Erros Inatos do Metabolismo/sangue , Erros Inatos do Metabolismo/metabolismo , Camundongos , Nitratos/sangue , Nitritos/sangue , Concentração Osmolar , Complexo Repressor Polycomb 1RESUMO
Parkinson's disease is a common incurable neurodegenerative disease whose molecular aetiology remains unclear. The identification of Mendelian genes causing rare familial forms of Parkinson's disease has revealed novel proteins and pathways that are likely to be relevant in the pathogenesis of sporadic Parkinson's disease. Recently, mutations in a novel gene, PINK1, encoding a 581 amino acid protein with both mitochondrial targeting and serine/threonine kinase domains, were identified as a cause of autosomal recessive parkinsonism. This provided important evidence for the role of the mitochondrial dysfunction and kinase pathways in neurodegeneration. In this study, we report the first characterization of the PINK1 protein in normal human and sporadic Parkinson's brains, in addition to Parkinson's cases with heterozygous PINK1 mutations. The possible role of the PINK1 protein was also assessed in a number of neurodegenerative diseases characterized by proteinaceous inclusions. For these studies, rabbit polyclonal antibodies were raised against two peptide sequences within the N-terminal hydrophilic loops of PINK1 protein. Using immunohistochemistry and western blotting we were able to demonstrate that PINK1 is a ubiquitous protein expressed throughout the human brain and it is found in all cell types showing a punctate cytoplasmic staining pattern consistent with mitochondrial localization. Fractionation studies of human and rat brain confirm that PINK1 is localized to the mitochondrial membranes. In addition, we show that PINK1 is detected in a proportion of Lewy bodies in cases of sporadic Parkinson's disease and Parkinson's disease associated with heterozygous mutations in the PINK1 gene, which are clinically and pathologically indistinguishable from the sporadic cases. PINK1 was absent in cortical Lewy bodies, in neurofibrillary tangles in Alzheimer's disease, progressive supranuclear palsy and corticobasal degeneration, and in the glial and neuronal alpha-synuclein positive inclusions in multiple system atrophy. These studies provide for the first time in vivo morphological and biochemical evidence to support a mitochondrial localization of PINK1 and underpin the significance of mitochondrial dysfunction in the pathogenesis of nigral cell degeneration in Parkinson's disease.
Assuntos
Encéfalo/metabolismo , Doença de Parkinson/metabolismo , Proteínas Quinases/metabolismo , Doença de Alzheimer/metabolismo , Animais , Carbonatos/farmacologia , Feminino , Heterozigoto , Humanos , Técnicas Imunoenzimáticas , Doença por Corpos de Lewy/metabolismo , Masculino , Pessoa de Meia-Idade , Mitocôndrias/metabolismo , Membranas Mitocondriais/metabolismo , Atrofia de Múltiplos Sistemas/metabolismo , Mutação , Doença de Parkinson/genética , Proteínas Quinases/genética , Ratos , Ratos Wistar , Partículas Submitocôndricas/efeitos dos fármacos , Partículas Submitocôndricas/metabolismoRESUMO
The nuclear-encoded Krebs cycle enzymes, fumarate hydratase (FH) and succinate dehydrogenase (SDHB, -C and -D), act as tumour suppressors. Germline mutations in FH predispose individuals to leiomyomas and renal cell cancer (HLRCC), whereas mutations in SDH cause paragangliomas and phaeochromocytomas (HPGL). In this study, we have shown that FH-deficient cells and tumours accumulate fumarate and, to a lesser extent, succinate. SDH-deficient tumours principally accumulate succinate. In situ analyses showed that these tumours also have over-expression of hypoxia-inducible factor 1alpha (HIF1alpha), activation of HIF1alphatargets (such as vascular endothelial growth factor) and high microvessel density. We found no evidence of increased reactive oxygen species in our cells. Our data provide in vivo evidence to support the hypothesis that increased succinate and/or fumarate causes stabilization of HIF1alpha a plausible mechanism, inhibition of HIF prolyl hydroxylases, has previously been suggested by in vitro studies. The basic mechanism of tumorigenesis in HPGL and HLRCC is likely to be pseudo-hypoxic drive, just as it is in von Hippel-Lindau syndrome.
Assuntos
Fumarato Hidratase/genética , Mutação em Linhagem Germinativa , Succinato Desidrogenase/genética , Succinato Desidrogenase/metabolismo , Carcinoma de Células Renais/metabolismo , Ciclo do Ácido Cítrico/fisiologia , Feminino , Fumarato Hidratase/metabolismo , Humanos , Leiomioma/genética , Leiomioma/metabolismo , Neoplasias/genética , Neoplasias/metabolismo , Paraganglioma/genética , Paraganglioma/metabolismo , Células Tumorais Cultivadas , Fator A de Crescimento do Endotélio Vascular/metabolismoAssuntos
Códon sem Sentido/genética , DNA Mitocondrial/genética , Tolerância ao Exercício/genética , Debilidade Muscular/genética , Músculo Esquelético/metabolismo , Doenças Musculares/genética , Análise Mutacional de DNA , Complexo I de Transporte de Elétrons/deficiência , Complexo I de Transporte de Elétrons/genética , Metabolismo Energético/genética , Feminino , Predisposição Genética para Doença/genética , Humanos , Pessoa de Meia-Idade , Mitocôndrias/genética , Mitocôndrias/metabolismo , Fibras Musculares Esqueléticas/metabolismo , Fibras Musculares Esqueléticas/patologia , Debilidade Muscular/metabolismo , Debilidade Muscular/fisiopatologia , Músculo Esquelético/patologia , Músculo Esquelético/fisiopatologia , Doenças Musculares/metabolismo , Doenças Musculares/fisiopatologia , NADH Desidrogenase/deficiência , NADH Desidrogenase/genética , Oftalmoplegia/genética , Oftalmoplegia/metabolismo , Oftalmoplegia/fisiopatologiaRESUMO
Glutathione (GSH) is a key intracellular antioxidant. With regard to mitochondrial function, loss of GSH is associated with impairment of the electron transport chain (ETC). Since GSH biosynthesis is an energy-dependent process, we postulated that in patients with ETC defects GSH status becomes compromised, leading to further loss of ETC activity. We performed electrochemical HPLC analysis to determine the GSH concentration of 24 skeletal muscle biopsies from patients with defined ETC defects compared to 15 age-matched disease controls. Comparison of these groups revealed a significant (p < 0.001) decrease in GSH concentration in the ETC-deficient group: 7.7 +/- 0.9 vs 12.3 +/- 0.6 nmol/mg protein in the control group. Further analysis of the data revealed that patients with multiple defects of the ETC had the most marked GSH deficiency: 4.1 +/- 0.9 nmol/mg protein (n = 4, p < 0.05) when compared to the control group. These findings suggest that a deficiency in skeletal muscle GSH concentration is associated with an ETC defect, possibly as a consequence of diminished ATP availability or increased oxidative stress. The decreased ability to combat oxidative stress could therefore cause further loss of ETC activity and hence be a contributing factor in the progressive nature of this group of disorders. Furthermore, restoration of cellular GSH status could prove to be of therapeutic benefit in patients with a GSH deficiency associated with their ETC defects.
Assuntos
Glutationa/deficiência , Doenças Mitocondriais/patologia , Doenças Mitocondriais/terapia , Trifosfato de Adenosina/metabolismo , Fatores Etários , Antioxidantes/farmacologia , Criança , Pré-Escolar , Cromatografia Líquida de Alta Pressão , Feminino , Glutationa/metabolismo , Humanos , Lactente , Masculino , Músculo Esquelético/metabolismo , Estresse Oxidativo , Fatores Sexuais , Fatores de TempoRESUMO
The antioxidant glutathione (GSH) plays an important role in protecting the mitochondrial electron transport chain (ETC) from damage by oxidative stress in astrocytes and neurones. Neurones co-cultured with astrocytes have greater GSH levels, compared to neurones cultured alone, leading to the hypothesis that astrocytes play a key role in brain GSH metabolism by supplying essential GSH precursors to neurones. A previous study has postulated that damage to the ETC following exposure to reactive nitrogen species (RNS) is less in co-cultured neurones, compared to neurones cultured alone, because of the greater GSH levels in the former cells. To investigate this further, primary culture rat neurones were co-cultured with either rat astrocytes activated with IFN-gamma and LPS to produce NO, or NO-generating astrocytes that had been depleted of intracellular GSH by 87% following incubation with the GSH synthesis inhibitor L-buthionine-S,R-sulfoximine (L-BSO). Neurones incubated with NO-generating astrocytes depleted of GSH were unable to elevate GSH levels, unlike neurones co-cultured with NO-generating astrocytes. Complexes II + III and IV of the neuronal ETC were significantly inhibited following exposure to NO-generating astrocytes depleted of GSH. No ETC damage was observed in neurones co-cultured with NO-generating astrocytes. Although neurones co-cultured with GSH depleted astrocytes did not increase cellular GSH levels, the activity of glutamate cysteine ligase (GCL), the rate-limiting enzyme of GSH synthesis, was increased by 218%, compared to neurones cultured with control astrocytes. This suggests that neuronal GCL activity could be modulated when GSH metabolism is inhibited in neighboring astrocytes.
Assuntos
Astrócitos/metabolismo , Glutamato-Cisteína Ligase/metabolismo , Glutationa/metabolismo , Neurônios/metabolismo , Óxido Nítrico/metabolismo , Estresse Oxidativo/fisiologia , Animais , Animais Recém-Nascidos , Astrócitos/efeitos dos fármacos , Encéfalo/metabolismo , Encéfalo/fisiopatologia , Comunicação Celular/efeitos dos fármacos , Comunicação Celular/fisiologia , Células Cultivadas , Técnicas de Cocultura , Complexo de Proteínas da Cadeia de Transporte de Elétrons/efeitos dos fármacos , Complexo de Proteínas da Cadeia de Transporte de Elétrons/metabolismo , Inibidores Enzimáticos/farmacologia , Glutationa/antagonistas & inibidores , Mediadores da Inflamação/farmacologia , Neurônios/efeitos dos fármacos , Óxido Nítrico/farmacologia , Estresse Oxidativo/efeitos dos fármacos , Ratos , Ratos Wistar , Regulação para Cima/efeitos dos fármacos , Regulação para Cima/fisiologiaRESUMO
The hph-1 mice have defective tetrahydrobiopterin biosynthesis and share many neurochemical similarities with l-dopa-responsive dystonia (DRD) in humans. In both, there are deficiencies in GTP cyclohydrolase I and low brain levels of dopamine (DA). Striatal tyrosine hydroxylase (TH) levels are decreased while the number of DA neurones in substantia nigra (SN) appears normal. The hph-1 mouse is therefore a useful model in which to investigate the biochemical mechanisms underlying dystonia in DRD. In the present study, the density of striatal DA terminals and DA receptors and the expression of D-1, D-2, and D-3 receptors, preproenkephalin (PPE-A), preprotachykinin (PPT), and nitric oxide synthase (NOS) mRNAs in the striatum and nucleus accumbens and nigral TH mRNA expression were examined. Striatal DA terminal density as judged by specific [3H]mazindol binding was not altered while the levels of TH mRNA were elevated in the SN of hph-1 mice compared to control (C57BL) mice. Total and subregional analysis of the striatum and nucleus accumbens showed that D-2 receptor ([3H]spiperone) binding density was increased while D-1 receptor ([3H]SCH 23390) and D-3 receptor ([3H]7-OH-DPAT) binding density was not altered. In the striatum and nucleus accumbens, expression of PPT mRNA was elevated but PPE-A mRNA, D-1, D-2 receptor, and nNOS mRNA were not changed in hph-1 mice compared to controls. These findings suggest that an imbalance between the direct strionigral and indirect striopallidal output pathways may be relevant to the genesis of DRD. However, the pattern of changes observed is not that expected as a result of striatal dopamine deficiency and suggests that other effects of GTP cyclohydrolase I deficiency may be involved.
Assuntos
Encéfalo/metabolismo , Distonia/metabolismo , GTP Cicloidrolase/deficiência , Neuropeptídeos/biossíntese , Receptores Dopaminérgicos/biossíntese , Animais , Autorradiografia , Encéfalo/patologia , Modelos Animais de Doenças , Distonia/fisiopatologia , Encefalinas/metabolismo , Hibridização In Situ , Camundongos , Óxido Nítrico Sintase/metabolismo , Óxido Nítrico Sintase Tipo I , Terminações Pré-Sinápticas/patologia , Precursores de Proteínas/metabolismo , RNA Mensageiro/análise , Taquicininas/metabolismo , Tirosina 3-Mono-Oxigenase/metabolismoRESUMO
Two girls and one boy are described, with severe infantile parkinsonism-dystonia. This syndrome is usually caused by endogenous dopamine deficiency but in these patients was associated with elevated dopamine metabolites in CSF and an unusual eye movement disorder: ocular flutter together with saccade initiation failure. Pyramidal tract signs also emerged in the course of the disease in two patients. This combination of symptoms and biochemical findings suggests a unique pathogenic mechanism.
Assuntos
Dopamina/líquido cefalorraquidiano , Distúrbios Distônicos/líquido cefalorraquidiano , Ácido Homovanílico/líquido cefalorraquidiano , Transtornos da Motilidade Ocular/líquido cefalorraquidiano , Doença de Parkinson/líquido cefalorraquidiano , Dopamina/urina , Distúrbios Distônicos/diagnóstico por imagem , Feminino , Ácido Homovanílico/urina , Humanos , Ácido Hidroxi-Indolacético/líquido cefalorraquidiano , Recém-Nascido , Masculino , Transtornos da Motilidade Ocular/diagnóstico por imagem , Doença de Parkinson/diagnóstico por imagem , Reflexo Anormal , Movimentos Sacádicos , Síndrome , Tomografia Computadorizada de Emissão de Fóton ÚnicoRESUMO
A case of pyruvate dehydrogenase E3 binding protein deficiency is reported in a 24-year-old male with encephalomyopathy. Blood lactate was only minimally elevated, as was alanine.