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1.
Pediatr Emerg Care ; 38(1): e37-e42, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34986585

RESUMO

OBJECTIVE: Mild traumatic brain injury (mTBI), or concussion, is a common health problem that has seen a recent increase in US adolescents. This study uses SMS text messaging (a mobile health [mHealth] tool) to report patient symptoms. We aim to better characterize mTBI recovery and hypothesize that this mHealth tool will have high retention rates and correlate with a conventional means of assessing symptoms, the Post-Concussion Symptom Inventory (PCSI). METHODS: A prospective observational cohort pilot study. Thirty-one pediatric patients with acute mTBI were recruited to characterize their injury and report their symptoms via text messaging. Patients reported symptoms once every 3 days for the first 21 days, then once a week for 6 weeks. RESULTS: There was a strong and positive correlation between the PCSI and the mHealth tool (rs = 0.875, P < 0.000, n = 22). Retention was 74% until symptom resolution and 42% until study completion. Patients with balance deficits had a significantly higher somatization score than those with normal balance (6.53 ± 3.25 vs 2.56 ± 2.30, t(22) = 3.211, P < 0.01). CONCLUSIONS: This pilot study demonstrates that this tool is a valid and easy-to-use method of reporting pediatric mTBI symptoms-it replicates and identifies novel findings. Our results suggest that there may be a relationship between balance and the manifestation of somatic symptoms. Retention rates were lower than predicted, indicating that text messaging may not be the ideal format in this population. Text messaging may still have other applications for short-term communication/symptom measurement.


Assuntos
Concussão Encefálica , Síndrome Pós-Concussão , Envio de Mensagens de Texto , Adolescente , Concussão Encefálica/diagnóstico , Criança , Humanos , Projetos Piloto , Síndrome Pós-Concussão/diagnóstico
2.
Am J Perinatol ; 36(9): 898-906, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-30396223

RESUMO

OBJECTIVE: This article systematically reviews the literature to establish the normal range of lactic acid in healthy pregnant women. STUDY DESIGN: Ovid MEDLINE, Embase.com, and Clinicaltrials.gov were searched to identify studies that reported maternal lactic acid in healthy pregnant women. Pooled aggregate means and two standard deviations for each time period were computed using the inverse variance weighting technique. Analyses were performed separately for 1st, 2nd, and 3rd trimesters, scheduled cesarean delivery, early labor, active labor, 2nd stage of labor, and delivery. RESULTS: Overall, 22 studies met the inclusion criteria. There were 1,193 patients, and 2,008 observations identified. All time periods had maternal venous lactic acid aggregate means and two-standard-deviation ranges less than 4 mmol/L. Outside of labor, all ranges were less than 2 mmol/L. All labor periods had a range higher than 2 mmol/L. While the pooled ranges were less than 4 mmol/L, many individual studies reported ranges > 4 mmol/L during labor. CONCLUSION: This meta-analysis suggests that venous lactic acid levels can be used as a screening tool in pregnant women just as the test would be used in nonpregnant women, except that elevations may be seen during labor, especially later in labor when there is maximal skeletal muscle contraction.


Assuntos
Trabalho de Parto/sangue , Ácido Láctico/sangue , Gravidez/sangue , Feminino , Humanos , Valores de Referência
3.
J Biol Chem ; 285(2): 1153-65, 2010 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-19892704

RESUMO

A decrease in reactive oxygen species (ROS) production has been associated with extended life span in animal models of longevity. Mice deficient in the p66Shc gene are long-lived, and their cells are both resistant to oxidative stress and produce less ROS. Our microarray analysis of p66Shc(-/-) mouse tissues showed alterations in transcripts involved in heme and superoxide production and insulin signaling. Thus, we carried out analysis of ROS production by NADPH oxidase (PHOX) in macrophages of control and p66Shc knock-out mice. p66Shc(-/-) mice had a 40% reduction in PHOX-dependent superoxide production. To confirm whether the defect in superoxide production was a direct consequence of p66Shc deficiency, p66Shc was knocked down with siRNA in the macrophage cell line RAW264, and a 30% defect in superoxide generation was observed. The pathway of PHOX-dependent superoxide generation was investigated. PHOX protein levels were not decreased in mutant macrophages; however, the rate and extent of phosphorylation of p47phox was decreased in mutants, as was membrane translocation of the complex. Consistently, phosphorylation of protein kinase Cdelta, Akt, and ERK (the kinases responsible for phosphorylation of p47phox) was decreased. Thus, p66Shc deficiency causes a defect in activation of the PHOX complex that results in decreased superoxide production. p66Shc-deficient mice have recently been observed to be resistant to atherosclerosis and to oxidant injury in kidney and brain. Because phagocyte-derived superoxide is often a component of oxidant injury and inflammation, we suggest that the decreased superoxide production by PHOX in p66Shc-deficient mice could contribute significantly to their relative protection from oxidant injury and consequent longevity.


Assuntos
Longevidade , NADPH Oxidases/metabolismo , Estresse Oxidativo , Proteínas Adaptadoras da Sinalização Shc , Superóxidos/metabolismo , Animais , Linhagem Celular , Ativação Enzimática/genética , MAP Quinases Reguladas por Sinal Extracelular/genética , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Perfilação da Expressão Gênica , Regulação da Expressão Gênica/genética , Técnicas de Silenciamento de Genes , Camundongos , Camundongos Knockout , NADPH Oxidases/genética , Análise de Sequência com Séries de Oligonucleotídeos , Proteína Quinase C-delta/genética , Proteína Quinase C-delta/metabolismo , Proteínas Proto-Oncogênicas c-akt/genética , Proteínas Proto-Oncogênicas c-akt/metabolismo , Proteína 1 de Transformação que Contém Domínio 2 de Homologia de Src
4.
Biochim Biophys Acta ; 1792(11): 1052-61, 2009 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-19679182

RESUMO

Mutations in the frataxin gene cause dorsal root ganglion demyelination and neurodegeneration, which leads to Friedreich's ataxia. However the consequences of frataxin depletion have not been measured in dorsal root ganglia or Schwann cells. We knocked down frataxin in several neural cell lines, including two dorsal root ganglia neural lines, 2 neuronal lines, a human oligodendroglial line (HOG) and multiple Schwann cell lines and measured cell death and proliferation. Only Schwann cells demonstrated a significant decrease in viability. In addition to the death of Schwann cells, frataxin decreased proliferation in Schwann, oligodendroglia, and slightly in one neural cell line. Thus the most severe effects of frataxin deficiency were on Schwann cells, which enwrap dorsal root ganglia neurons. Microarray of frataxin-deficient Schwann cells demonstrated strong activations of inflammatory and cell death genes including interleukin-6 and Tumor Necrosis Factor which were confirmed at the mRNA and protein levels. Frataxin knockdown in Schwann cells also specifically induced inflammatory arachidonate metabolites. Anti-inflammatory and anti-apoptotic drugs significantly rescued frataxin-dependent Schwann cell toxicity. Thus, frataxin deficiency triggers inflammatory changes and death of Schwann cells that is inhibitable by inflammatory and anti-apoptotic drugs.


Assuntos
Gânglios Espinais/metabolismo , Transtornos Heredodegenerativos do Sistema Nervoso/metabolismo , Proteínas de Ligação ao Ferro , Mutação , Neurônios/metabolismo , Morte Celular/genética , Linhagem Celular , Sobrevivência Celular , Gânglios Espinais/patologia , Técnicas de Silenciamento de Genes , Transtornos Heredodegenerativos do Sistema Nervoso/genética , Transtornos Heredodegenerativos do Sistema Nervoso/patologia , Humanos , Inflamação/genética , Inflamação/metabolismo , Inflamação/patologia , Interleucina-6/genética , Interleucina-6/metabolismo , Neurônios/patologia , Células de Schwann , Frataxina
5.
Bioorg Med Chem ; 18(17): 6429-41, 2010 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-20691600

RESUMO

Analogues of mitoQ and idebenone were synthesized to define the structural elements that support oxygen consumption in the mitochondrial respiratory chain. Eight analogues were prepared and fully characterized, then evaluated for their ability to support oxygen consumption in the mitochondrial respiratory chain. While oxygen consumption was strongly inhibited by mitoQ analogues 2-4 in a chain length-dependent manner, modification of idebenone by replacement of the quinone methoxy groups by methyl groups (analogues 6-8) reduced, but did not eliminate, oxygen consumption. Idebenone analogues 6-8 also displayed significant cytoprotective properties toward cultured mammalian cells in which glutathione had been depleted by treatment with diethyl maleate.


Assuntos
Mitocôndrias/efeitos dos fármacos , Compostos Organofosforados/síntese química , Compostos Organofosforados/farmacologia , Consumo de Oxigênio/efeitos dos fármacos , Ubiquinona/análogos & derivados , Antioxidantes/síntese química , Antioxidantes/farmacologia , Citoproteção , Glutationa/metabolismo , Humanos , Mitocôndrias/metabolismo , Ubiquinona/síntese química , Ubiquinona/farmacologia
6.
Neurology ; 94(6): e626-e634, 2020 02 11.
Artigo em Inglês | MEDLINE | ID: mdl-31831599

RESUMO

OBJECTIVE: To determine whether the sacral anatomical interspace landmark (SAIL) technique is more accurate than the classic intercristal line (ICL) technique in pregnant patients and to assess the percentage of clinical determinations above the third lumbar vertebra. METHODS: In this prospective, randomized, open-label trial, there were 110 singleton pregnant patients with gestational age greater than 37 weeks included. Selection procedure was a convenience sample of pregnant patients who presented for office visits or vaginal or cesarean delivery between March 15 and July 31, 2018, at a single-center obstetric tertiary care university hospital. Both techniques were evaluated by 2 physicians independently assessing each method. Before data collection, we hypothesized that the SAIL technique would be more accurate than the ICL technique in determining the L4-L5 interspace, and that the SAIL technique would produce more estimations below the third lumbar vertebra than the ICL technique. Therefore, the primary outcome was accuracy in identifying the L4-L5 lumbar interspace with SAIL vs ICL. The secondary outcome was difference in clinical assessments above the third lumbar vertebra. Both outcomes were measured via ultrasonography. RESULTS: Patients were 31 ± 5 years of age (mean ± SD) and had body mass index of 31.8 ± 5.7 kg/m2 and gestational age of 38.8 ± 1.1 weeks. A total of 110 patients were analyzed. SAIL correctly identified the L4-L5 interspace 49% of the time vs 8% using ICL (p < 0.0001). Estimations above L3 were 1% for SAIL vs 31% for ICL (p < 0.0001). CONCLUSIONS: Our study shows improved accuracy in identifying intervertebral space using the SAIL technique; this may prevent direct mechanical trauma to the conus medullaris when lumbar punctures are performed in pregnancy. CLINICALTRIALSGOV IDENTIFIER: NCT03433612.


Assuntos
Pontos de Referência Anatômicos , Ílio/anatomia & histologia , Vértebras Lombares/anatomia & histologia , Sacro/anatomia & histologia , Punção Espinal/métodos , Adulto , Anestesia Epidural/métodos , Índice de Massa Corporal , Feminino , Idade Gestacional , Humanos , Exame Físico , Gravidez , Terceiro Trimestre da Gravidez , Ultrassonografia
7.
J Drugs Dermatol ; 7(3): 266-71, 2008 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-18380208

RESUMO

BACKGROUND: Hydrocortisone butyrate (HCB) is currently marketed as a cream, ointment, and solution. A new lotion formulation of hydrocortisone butyrate 0.1% (Locoid lotion) has been developed and evaluated. OBJECTIVE: The objective of this study was to evaluate the efficacy and safety of HCB 0.1% lotion compared to the vehicle in subjects aged 3 months to less than 18 years with mild to moderate atopic dermatitis (AD). METHODS: In this multicenter double-blind study, 284 subjects with mild to moderate AD were randomized 1:1 to receive HCB 0.1% lotion or the vehicle for a duration of 4 weeks. "Treatment success" was defined as those subjects with a final Physician Global Assessment (PGA) score of 0 or 1 that had at least a 2-point reduction in the PGA score from baseline to day 29. Safety was assessed by monitoring adverse events. RESULTS: Analyses of the final PGA score showed a significant treatment effect (P <.001) in favor of the HCB 0.1% lotion group. The safety profile of the HCB 0.1% lotion was also favorable. LIMITATIONS: The study did not assess the durability of the treatment effects (ie, safety and efficacy) after completion of the 4-week treatment period nor the potential need for longer term therapy given the chronic nature of AD. CONCLUSION: Results demonstrate the safety and efficacy of HCB 0.1% lotion in the treatment of mild to moderate AD in children 3 months to 18 years of age.


Assuntos
Dermatite Atópica/tratamento farmacológico , Hidrocortisona/análogos & derivados , Imunossupressores/uso terapêutico , Administração Cutânea , Adolescente , Criança , Pré-Escolar , Dermatite Atópica/complicações , Método Duplo-Cego , Feminino , Humanos , Hidrocortisona/efeitos adversos , Hidrocortisona/uso terapêutico , Imunossupressores/efeitos adversos , Lactente , Masculino , Prurido/tratamento farmacológico , Prurido/etiologia , Índice de Gravidade de Doença , Resultado do Tratamento
8.
Free Radic Biol Med ; 42(1): 32-43, 2007 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-17157191

RESUMO

Deletions within the mitochondrial DNA (mtDNA) cause Kearns Sayre syndrome (KSS) and chronic progressive external opthalmoplegia (CPEO). The clinical signs of KSS include muscle weakness, heart block, pigmentary retinopathy, ataxia, deafness, short stature, and dementia. The identical deletions occur and rise exponentially as humans age, particularly in substantia nigra. Deletions at >30% concentration cause deficits in basic bioenergetic parameters, including membrane potential and ATP synthesis, but it is poorly understood how these alterations cause the pathologies observed in patients. To better understand the consequences of mtDNA deletions, we microarrayed six cell types containing mtDNA deletions from KSS and CPEO patients. There was a prominent inhibition of transcripts encoding ubiquitin-mediated proteasome activity, and a prominent induction of transcripts involved in the AMP kinase pathway, macroautophagy, and amino acid degradation. In mutant cells, we confirmed a decrease in proteasome biochemical activity, significantly lower concentration of several amino acids, and induction of an autophagic transcript. An interpretation consistent with the data is that mtDNA deletions increase protein damage, inhibit the ubiquitin-proteasome system, decrease amino acid salvage, and activate autophagy. This provides a novel pathophysiological mechanism for these diseases, and suggests potential therapeutic strategies.


Assuntos
Autofagia , Biomarcadores/metabolismo , DNA Mitocondrial/genética , Síndrome de Kearns-Sayre/genética , Oftalmoplegia Externa Progressiva Crônica/genética , Inibidores de Proteassoma , Deleção de Sequência , Células Cultivadas , Perfilação da Expressão Gênica , Humanos , Síndrome de Kearns-Sayre/metabolismo , Análise de Sequência com Séries de Oligonucleotídeos , Oftalmoplegia Externa Progressiva Crônica/metabolismo , Complexo de Endopeptidases do Proteassoma/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transcrição Gênica , Ubiquitina/metabolismo
9.
Obstet Gynecol ; 130(1): 29-35, 2017 07.
Artigo em Inglês | MEDLINE | ID: mdl-28594763

RESUMO

OBJECTIVE: To define the amount of opioid analgesics prescribed and consumed after discharge after cesarean delivery. METHODS: We conducted a survey at six academic medical centers in the United States from September 2014 to March 2016. Women who had undergone a cesarean delivery were contacted by phone 2 weeks after discharge and participated in a structured interview about the opioid prescription they received on discharge and their oral opioid intake while at home. RESULTS: A total of 720 women were enrolled; of these, 615 (85.4%) filled an opioid prescription. The median number of dispensed opioid tablets was 40 (interquartile range 30-40), the median number consumed was 20 (interquartile range 8-30), and leftover was 15 (interquartile range 3-26). Of those with leftover opioids, 95.3% had not disposed of the excess medication at the time of the interview. There was an association between a larger number of tablets dispensed and the number consumed independent of patient characteristics. The amount of opioids dispensed did not correlate with patient satisfaction, pain control, or the need to refill the opioid prescription. CONCLUSION: The amount of opioid prescribed after cesarean delivery generally exceeds the amount consumed by a significant margin, leading to substantial amounts of leftover opioid medication. Lower opioid prescription correlates with lower consumption without a concomitant increase in pain scores or satisfaction.


Assuntos
Analgésicos Opioides/uso terapêutico , Cesárea , Dor Pós-Operatória/prevenção & controle , Padrões de Prática Médica , Adulto , Analgésicos Opioides/provisão & distribuição , Feminino , Humanos , Entrevistas como Assunto , Serviços de Saúde Materna , Transtornos Relacionados ao Uso de Opioides/prevenção & controle , Gravidez , Estados Unidos
10.
Antioxid Redox Signal ; 19(13): 1481-93, 2013 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-23350650

RESUMO

AIMS: Oxidative stress is thought to be involved in Friedreich's ataxia (FRDA), yet it has not been demonstrated in the target neurons that are first to degenerate. Using the YG8R mouse model of FRDA, microarray and neuritic growth experiments were carried out in the dorsal root ganglion (DRG), the primary site of neurodegeneration in this disease. RESULTS: YG8R hemizygous mice exhibited defects in movement, and DRG neurites had growth defects. Microarray of DRG tissue identified decreased transcripts encoding the antioxidants, including peroxiredoxins, glutaredoxins, and glutathione S-transferase, and these were confirmed by immunoblots and quantitative real-time PCR. Because the decreased gene transcripts are the known targets of the antioxidant transcription factor nuclear factor-E2-related factor-2 (Nrf2), Nrf2 expression was measured; it was significantly decreased at the transcript and protein level in both the DRG and the cerebella of the YG8R hemizygous mouse; further, frataxin expression was significantly correlated with Nrf2 expression. Functionally, in YG8R hemizygous DRG, the total glutathione levels were reduced and explanted cells were more sensitive to the thioredoxin reductase (TxnRD) inhibitor auranofin, a thiol oxidant. In cell models of FRDA, including Schwann and the DRG, frataxin deficiency caused a decreased expression of the Nrf2 protein level in the nucleus, but not a defect in its translocation from the cytosol. Further, frataxin-deficient cells had decreased enzyme activity and expression of TxnRD, which is regulated by Nrf2, and were sensitive the TxnRD inhibitor auranofin. INNOVATION AND CONCLUSION: These results support a mechanistic hypothesis in which frataxin deficiency decreases Nrf2 expression in vivo, causing the sensitivity to oxidative stress in target tissues the DRG and the cerebella, which contributes to the process of neurodegeneration.


Assuntos
Antioxidantes/metabolismo , Modelos Animais de Doenças , Ataxia de Friedreich/metabolismo , Gânglios Espinais/metabolismo , Proteínas de Ligação ao Ferro/metabolismo , Fator 2 Relacionado a NF-E2/biossíntese , Animais , Células Cultivadas , Ataxia de Friedreich/genética , Células HeLa , Humanos , Proteínas de Ligação ao Ferro/genética , Camundongos , Camundongos Endogâmicos C57BL , Fator 2 Relacionado a NF-E2/genética , Ratos , Frataxina
11.
PLoS One ; 7(8): e42504, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-22900024

RESUMO

Etiology of aberrant social behavior consistently points to a strong polygenetic component involved in fundamental developmental pathways, with the potential of being enhanced by defects in bioenergetics. To this end, the occurrence of social deficits and mitochondrial outcomes were evaluated in conditional Pten (Phosphatase and tensin homolog) haplo-insufficient mice, in which only one allele was selectively knocked-out in neural tissues. Pten mutations have been linked to Alzheimer's disease and syndromic autism spectrum disorders, among others. By 4-6 weeks of age, Pten insufficiency resulted in the increase of several mitochondrial Complex activities (II-III, IV and V) not accompanied by increases in mitochondrial mass, consistent with an activation of the PI3K/Akt pathway, of which Pten is a negative modulator. At 8-13 weeks of age, Pten haplo-insufficient mice did not show significant behavioral abnormalities or changes in mitochondrial outcomes, but by 20-29 weeks, they displayed aberrant social behavior (social avoidance, failure to recognize familiar mouse, and repetitive self-grooming), macrocephaly, increased oxidative stress, decreased cytochrome c oxidase (CCO) activity (50%) and increased mtDNA deletions in cerebellum and hippocampus. Mitochondrial dysfunction was the result of a downregulation of p53-signaling pathway evaluated by lower protein expression of p21 (65% of controls) and the CCO chaperone SCO2 (47% of controls), two p53-downstream targets. This mechanism was confirmed in Pten-deficient striatal neurons and, HCT 116 cells with different p53 gene dosage. These results suggest a unique pathogenic mechanism of the Pten-p53 axis in mice with aberrant social behavior: loss of Pten (via p53) impairs mitochondrial function elicited by an early defective assembly of CCO and later enhanced by the accumulation of mtDNA deletions. Consistent with our results, (i) SCO2 deficiency and/or CCO activity defects have been reported in patients with learning disabilities including autism and (ii) mutated proteins in ASD have been found associated with p53-signaling pathways.


Assuntos
Haploinsuficiência/genética , Mitocôndrias/genética , PTEN Fosfo-Hidrolase/genética , Transtornos do Comportamento Social/genética , Proteína Supressora de Tumor p53/genética , Animais , Comportamento Animal , Córtex Cerebelar/metabolismo , Cerebelo/metabolismo , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Feminino , Células HCT116 , Hipocampo/metabolismo , Humanos , Masculino , Megalencefalia/genética , Camundongos , Camundongos Knockout , Mitocôndrias/metabolismo , Neurônios/metabolismo , PTEN Fosfo-Hidrolase/metabolismo , Transtornos do Comportamento Social/metabolismo , Proteína Supressora de Tumor p53/metabolismo
12.
Mitochondrion ; 10(2): 143-50, 2010 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-20005986

RESUMO

Demyelination occurs in multiple inherited mitochondrial diseases. We studied which genes were induced as a consequence of differentiation in rodent and human oligodendroglia. Cholesterol, myelin and mitochondrial genes were significantly increased with oligodendroglial differentiation. Mitochondrial DNA content per cell and acetyl CoA-related transcripts increased significantly; thus, the large buildup of cholesterol necessary for myelination appears to require mitochondrial production of acetyl-CoA. Oligodendroglia were treated with low doses of the mitochondrial inhibitor rotenone to test the dependence of differentiation on mitochondrial function. Undifferentiated cells were resistant to rotenone, whereas differentiating cells were much more sensitive. Very low doses of rotenone that did not affect viability or ATP synthesis still inhibited differentiation, as measured by reduced levels of the myelin transcripts 2',3'-Cyclic Nucleotide-3'-Phosphodiesterase and Myelin Basic Protein. Thus, mitochondrial transcripts and mtDNA are amplified during oligodendroglial differentiation, and differentiating oligodendroglia are especially sensitive to mitochondrial inhibition, suggesting mechanisms for demyelination observed in mitochondrial disease.


Assuntos
Diferenciação Celular , Genes Mitocondriais , Mitocôndrias/fisiologia , Oligodendroglia/fisiologia , Ativação Transcricional , Acetilcoenzima A/metabolismo , Humanos , Redes e Vias Metabólicas/genética , Rotenona/farmacologia , Desacopladores/farmacologia
14.
Hum Mol Genet ; 14(24): 3787-99, 2005 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-16239244

RESUMO

Deficiency of the frataxin mRNA alters the transcriptome, triggering neuro- and cardiodegeneration in Friedreich's ataxia. We microarrayed murine frataxin-deficient heart tissue, liver tissue and cardiocytes and observed a transcript down-regulation to up-regulation ratio of nearly 2:1 with a mitochondrial localization of transcriptional changes. Combining all mouse and human microarray data for frataxin-deficient cells and tissues, the most consistently decreased transcripts were mitochondrial coproporphyrinogen oxidase (CPOX) of the heme pathway and mature T-cell proliferation 1, a homolog of yeast COX23, which is thought to function as a mitochondrial metallochaperone. Quantitative RT-PCR studies confirmed the significant down-regulation of Isu1, CPOX and ferrochelatase at 10 weeks in mouse hearts. We observed that mutant cells were resistant to aminolevulinate-dependent toxicity, as expected if the heme pathway was inhibited. Consistent with this, we observed increased cellular protoporphyrin IX levels, reduced mitochondrial heme a and heme c levels and reduced activity of cytochrome oxidase, suggesting a defect between protoporphyrin IX and heme a. Fe-chelatase activities were similar in mutants and controls, whereas Zn-chelatase activities were slightly elevated in mutants, supporting the idea of an altered metal-specificity of ferrochelatase. These results suggest that frataxin deficiency causes defects late in the heme pathway. As ataxic symptoms occur in other diseases of heme deficiency, the heme defect we observe in frataxin-deficient cells could be primary to the pathophysiological process.


Assuntos
Heme/metabolismo , Proteínas de Ligação ao Ferro/metabolismo , Mitocôndrias/metabolismo , Sequência de Aminoácidos , Animais , Células Cultivadas , Coproporfirinogênio Oxidase/genética , Coproporfirinogênio Oxidase/metabolismo , Citocromos c/metabolismo , Ferroquelatase/genética , Ferroquelatase/metabolismo , Coração/embriologia , Heme/genética , Humanos , Proteínas de Ligação ao Ferro/genética , Mamíferos , Camundongos , Camundongos Knockout , Mitocôndrias/genética , Dados de Sequência Molecular , Mutação , Miocárdio/metabolismo , Análise de Sequência com Séries de Oligonucleotídeos , Proteínas Proto-Oncogênicas/genética , Proteínas Proto-Oncogênicas/metabolismo , Protoporfirinas/metabolismo , Homologia de Sequência de Aminoácidos , Transcrição Gênica , Zinco/metabolismo , Frataxina
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