Julkaisuarkisto

Primary mitochondrial diseases frequently affect the central nervous system, yet the extent, distribution and progression of white matter hyperintensities (WMHs) remain insufficiently characterised, particularly in terms of quantitative volumetrics and longitudinal progression. Although WMHs are typically attributed to cerebral small-vessel disease, mitochondrial disorders may cause white matter injury through distinct vascular and metabolic mechanisms. We conducted a retrospective single-centre study at Turku University Hospital including 36 patients with mitochondrial disease, each with at least one brain MRI (73 images). Longitudinal data were available for 15 patients. Three-dimensional T1-weighted and FLAIR images (1.5/3 T) were analysed with the FDA-cleared cNeuro tool to obtain intracranial volume-normalised WMH and lesion volumes and an automated global Fazekas score. At baseline (median age 49 years), WMHs were present in all supratentorial regions. Over time, WMH volumes increased significantly in periventricular, deep and juxtacortical regions, while lesion progression was predominantly periventricular. Fazekas scores remained generally low and stable. In follow-up imaging, women and patients carrying the m.3243A>G variant showed a greater burden of WMHs and lesions, compared with men and those with other mitochondrial diagnoses. WMH load did not differ according to history of stroke-like episodes. Mitochondrial disease is associated with early and progressive WMH accumulation, particularly in individuals with the m.3243A>G variant, and the pattern exceeds what would be expected from conventional vascular risk factors alone. These findings support a disease-specific mechanism of white matter vulnerability and highlight the importance of quantitative MRI for monitoring progression in mitochondrial disease.

Redox-mediated flow batteries boost energy density by utilizing dissolved redox species as charge carriers for solid charge-storage materials. This strategy strongly depends on the thermodynamics and kinetics between the solid booster and dissolved redox species. Conventional electrochemical methods often convolute intrinsic reactivity with mass transport effects, introducing complexity in determining limiting steps. We propose a strategy that confines solid boosters within recessed microelectrodes and employs scanning electrochemical microscopy (SECM) to estimate reaction kinetics between booster and dissolved active redox species. Confining the solid booster in the recessed microelectrode overcomes mass transport limitations of dissolved redox species and enables controlled polarization of the booster material, allowing deconvolution of key rate-determining factors. As an initial model system, Prussian blue-ferricyanide/ferrocyanide [Fe(CN)6]3-/4- was used as solid booster and dissolved redox active species, respectively. The methodology was further explored for copper hexacyanoferrate with N,N,N-2,2,6,6-heptamethylpiperidinyl oxy-4-ammonium chloride and nickel hydroxide with [Fe(CN)6]3-/4- and extended to Mn-based Prussian blue analogues in combination with organic redox species. Our results demonstrate that SECM coupled with the proposed recessed microelectrode strategy provides a powerful platform to disentangle interfacial kinetics and guide the rational design of solid booster-dissolved redox species and electrolytes for high-performance redox-mediated flow batteries.