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- Aad, G., et al.
(författare)
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- 2012
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swepub:Mat__t (refereegranskat)
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| 5. |
- Boczonadi, V., et al.
(författare)
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Investigating the role of the physiological isoform switch of cytochrome c oxidase subunits in reversible mitochondrial disease
- 2015
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Ingår i: International Journal of Biochemistry & Cell Biology. - : Elsevier BV. - 1357-2725. ; 63, s. 32-40
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Tidskriftsartikel (refereegranskat)abstract
- Reversible infantile respiratory chain deficiency is characterised by spontaneous recovery of mitochondrial myopathy in infants. We studied whether a physiological isoform switch of nuclear cytochrome c oxidase subunits contributes to the age-dependent manifestation and spontaneous recovery in reversible mitochondrial disease. Some nuclear-encoded subunits of cytochrome c oxidase are present as tissue-specific isoforms. Isoforms of subunits COX6A and COX7A expressed in heart and skeletal muscle are different from isoforms expressed in the liver, kidney and brain. Furthermore, in skeletal muscle both the heart and liver isoforms of subunit COX7A have been demonstrated with variable levels, indicating that the tissue-specific expression of nuclear-encoded subunits could provide a basis for the fine-tuning of cytochrome c oxidase activity to the specific metabolic needs of the different tissues. We demonstrate a developmental isoform switch of COX6A and COX7A subunits in human and mouse skeletal muscle. While the liver type isoforms are more present soon after birth, the heart/muscle isoforms gradually increase around 3 months of age in infants, 4 weeks of age in mice, and these isoforms persist in muscle throughout life. Our data in follow-up biopsies of patients with reversible infantile respiratory chain deficiency indicate that the physiological isoform switch does not contribute to the clinical manifestation and to the spontaneous recovery of this disease. However, understanding developmental changes of the different cytochrome c oxidase isoforms may have implications for other mitochondrial diseases. This article is part of a Directed Issue entitled: Energy Metabolism Disorders and Therapies. (C) 2015 Elsevier Ltd. All rights reserved.
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| 7. |
- Campbell, C., et al.
(författare)
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Meta-analyses of ataluren randomized controlled trials in nonsense mutation Duchenne muscular dystrophy
- 2020
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Ingår i: Journal of Comparative Effectiveness Research. - : Becaris Publishing Limited. - 2042-6305 .- 2042-6313. ; 9:14
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Tidskriftsartikel (refereegranskat)abstract
- Aim:Assess the totality of efficacy evidence for ataluren in patients with nonsense mutation Duchenne muscular dystrophy (nmDMD).Materials & methods:Data from the two completed randomized controlled trials (ClinicalTrials.gov: NCT00592553; NCT01826487) of ataluren in nmDMD were combined to examine the intent-to-treat (ITT) populations and two patient subgroups (baseline 6-min walk distance [6MWD] >= 300-<400 or <400 m). Meta-analyses examined 6MWD change from baseline to week 48.Results:Statistically significant differences in 6MWD change with ataluren versus placebo were observed across all three meta-analyses. Least-squares mean difference (95% CI): ITT (n = 342), +17.2 (0.2-34.1) m, p = 0.0473; >= 300-<400 m (n = 143), +43.9 (18.2-69.6) m, p = 0.0008; <400 m (n = 216), +27.7 (6.4-49.0) m, p = 0.0109.Conclusion:These meta-analyses support previous evidence for ataluren in slowing disease progression versus placebo in patients with nmDMD over 48 weeks. Treatment benefit was most evident in patients with a baseline 6MWD >= 300-<400 m (the ambulatory transition phase), thereby informing future trial design.
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| 8. |
- Euro, L., et al.
(författare)
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Structural modeling of tissue-specific mitochondrial alanyl-tRNA synthetase (AARS2) defects predicts differential effects on aminoacylation
- 2015
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Ingår i: Frontiers in Genetics. - : Frontiers Media SA. - 1664-8021. ; 5:FEB
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Tidskriftsartikel (refereegranskat)abstract
- The accuracy of mitochondrial protein synthesis is dependent on the coordinated action of nuclear-encoded mitochondrial aminoacyl-tRNA synthetases (mtARSs) and the mitochondrial DNA-encoded tRNAs. The recent advances in whole-exome sequencing have revealed the importance of the mtARS proteins for mitochondrial pathophysiology since nearly every nuclear gene for mtARS (out of 19) is now recognized as a disease gene for mitochondrial disease. Typically, defects in each mtARS have been identified in one tissue-specific disease, most commonly affecting the brain, or in one syndrome. However, mutations in the AARS2 gene for mitochondrial alanyl-tRNA synthetase (mtAlaRS) have been reported both in patients with infantile-onset cardiomyopathy and in patients with childhood to adulthood-onset leukoencephalopathy. We present here an investigation of the effects of the described mutations on the structure of the synthetase, in an effort to understand the tissue-specific outcomes of the different mutations. The mtAlaRS differs from the other mtARSs because in addition to the aminoacylation domain, it has a conserved editing domain for deacylating tRNAs that have been mischarged with incorrect amino acids. We show that the cardiomyopathy phenotype results from a single allele, causing an amino acid change R592W in the editing domain of AARS2, whereas the leukodystrophy mutations are located in other domains of the synthetase. Nevertheless, our structural analysis predicts that all mutations reduce the aminoacylation activity of the synthetase, because all mtAlaRS domains contribute to tRNA binding for aminoacylation. According to our model, the cardiomyopathy mutations severely compromise aminoacylation whereas partial activity is retained by the mutation combinations found in the leukodystrophy patients. These predictions provide a hypothesis for the molecular basis of the distinct tissue-specific phenotypic outcomes.
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| 9. |
- Hathazi, D., et al.
(författare)
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Metabolic shift underlies recovery in reversible infantile respiratory chain deficiency
- 2020
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Ingår i: Embo Journal. - : EMBO. - 0261-4189 .- 1460-2075. ; 39:23
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Tidskriftsartikel (refereegranskat)abstract
- Reversible infantile respiratory chain deficiency (RIRCD) is a rare mitochondrial myopathy leading to severe metabolic disturbances in infants, which recover spontaneously after 6-months of age. RIRCD is associated with the homoplasmic m.14674T>C mitochondrial DNA mutation; however, only similar to 1/100 carriers develop the disease. We studied 27 affected and 15 unaffected individuals from 19 families and found additional heterozygous mutations in nuclear genes interacting with mt-tRNAGlu including EARS2 and TRMU in the majority of affected individuals, but not in healthy carriers of m.14674T>C, supporting a digenic inheritance. Our transcriptomic and proteomic analysis of patient muscle suggests a stepwise mechanism where first, the integrated stress response associated with increased FGF21 and GDF15 expression enhances the metabolism modulated by serine biosynthesis, one carbon metabolism, TCA lipid oxidation and amino acid availability, while in the second step mTOR activation leads to increased mitochondrial biogenesis. Our data suggest that the spontaneous recovery in infants with digenic mutations may be modulated by the above described changes. Similar mechanisms may explain the variable penetrance and tissue specificity of other mtDNA mutations and highlight the potential role of amino acids in improving mitochondrial disease.
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| 10. |
- Landfeldt, E., et al.
(författare)
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Assessment of face validity of a disease model of nonsense mutation Duchenne muscular dystrophy: a multi-national Delphi panel study
- 2022
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Ingår i: Journal of Medical Economics. - : Informa UK Limited. - 1369-6998 .- 1941-837X. ; 25:1, s. 808-816
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Tidskriftsartikel (refereegranskat)abstract
- Objective The objective of this study was to assess the face validity of a disease model evaluating the cost-effectiveness of ataluren for the treatment of nonsense mutation Duchenne muscular dystrophy (nmDMD). Methods This was a Delphi panel study comprising of physicians with first-hand experience of ataluren for the treatment of nmDMD. Consensus was sought for previously unvalidated model data, including patient health status and quality of life measured using the Health Utility Index (HUI), mortality, informal caregiving, and the expected benefit of early ataluren treatment across four states: (1) ambulatory, (2) non-ambulatory, not yet requiring ventilation support, (3) non-ambulatory, night-time ventilation support, and (4) non-ambulatory, full-time ventilation support. Results Nine experts from five countries participated in the Delphi panel. Consensus was obtained for all questions after three panel rounds (except for two HUI-questions concerning hand function [dexterity]). Consensus HUI-derived utilities for state (1) were 1.0000 for ataluren on top of best supportive care (BSC) and 0.7337 for BSC alone. Corresponding estimates for state (2) were 0.3179 and 0.2672, for state (3) 0.1643 and 0.0913, and for state (4) -0.0732 and -0.1163. Consensus mortality rates for states (1), (2), and (3) were 4%, 13%, and 33%, and life expectancy in state (4) was agreed to be 3 years. Panelists further agreed that two informal caregivers typically provide day-to-day care/support to patients with nmDMD, and that starting treatment with ataluren at 2 versus 5 years of age would be expected to delay loss of ambulation by an additional 2 years, and initiation of night-time and full-time ventilation support by an additional 3 years, respectively. Limitations The main limitation concerns the size of the Delphi panel, govern primarily by the rarity of the disease. Conclusion This study confirms the face validity of key clinical parameters and assumptions underlying the ataluren cost-effectiveness model.
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