27 research outputs found

    Dyclonine rescues frataxin deficiency in animal models and buccal cells of patients with Friedreich's ataxia.

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    Inherited deficiency in the mitochondrial protein frataxin (FXN) causes the rare disease Friedreich's ataxia (FA), for which there is no successful treatment. We identified a redox deficiency in FA cells and used this to model the disease. We screened a 1600-compound library to identify existing drugs, which could be of therapeutic benefit. We identified the topical anesthetic dyclonine as protective. Dyclonine increased FXN transcript and FXN protein dose-dependently in FA cells and brains of animal models. Dyclonine also rescued FXN-dependent enzyme deficiencies in the iron-sulfur enzymes, aconitase and succinate dehydrogenase. Dyclonine induces the Nrf2 [nuclear factor (erythroid-derived 2)-like 2] transcription factor, which we show binds an upstream response element in the FXN locus. Additionally, dyclonine also inhibited the activity of histone methyltransferase G9a, known to methylate histone H3K9 to silence FA chromatin. Chronic dosing in a FA mouse model prevented a performance decline in balance beam studies. A human clinical proof-of-concept study was completed in eight FA patients dosed twice daily using a 1% dyclonine rinse for 1 week. Six of the eight patients showed an increase in buccal cell FXN levels, and fold induction was significantly correlated with disease severity. Dyclonine represents a novel therapeutic strategy that can potentially be repurposed for the treatment of FA

    Identification of region-specific astrocyte subtypes at single cell resolution

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    Astrocytes, a major cell type found throughout the central nervous system, have general roles in the modulation of synapse formation and synaptic transmission, blood-brain barrier formation, and regulation of blood flow, as well as metabolic support of other brain resident cells. Crucially, emerging evidence shows specific adaptations and astrocyte-encoded functions in regions, such as the spinal cord and cerebellum. To investigate the true extent of astrocyte molecular diversity across forebrain regions, we used single-cell RNA sequencing. Our analysis identifies five transcriptomically distinct astrocyte subtypes in adult mouse cortex and hippocampus. Validation of our data in situ reveals distinct spatial positioning of defined subtypes, reflecting the distribution of morphologically and physiologically distinct astrocyte populations. Our findings are evidence for specialized astrocyte subtypes between and within brain regions. The data are available through an online database (https://holt-sc.glialab.org/), providing a resource on which to base explorations of local astrocyte diversity and function in the brain.status: publishe

    Correspondence between neurophysiological and clinical measurements of chemotherapy-induced peripheral neuropathy: secondary analysis of data from the CI-PeriNoms study

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    Chemotherapy-induced peripheral neuropathy (CIPN) lacks standardized clinical measurement. The objective of the current secondary analysis was to examine data from the CIPN Outcomes Standardization (CI-PeriNomS) study for associations between clinical examinations and neurophysiological abnormalities. Logistic regression estimated the strength of associations of vibration, pin, and monofilament examinations with lower limb sensory and motor amplitudes. Examinations were classified as normal (0), moderately abnormal (1), or severely abnormal (2). Among 218 participants, those with class 1 upper extremity (UE) and classes 1 or 2 lower extremity (LE) monofilament abnormality were 2.79 (95% confidence interval [CI]: 1.28-6.07), 3.49 (95%CI: 1.61-7.55), and 4.42 (95%CI: 1.35-14.46) times more likely to have abnormal sural nerve amplitudes, respectively, compared to individuals with normal examinations. Likewise, those with class 2 UE and classes 1 or 2 LE vibration abnormality were 8.65 (95%CI: 1.81-41.42), 2.54 (95%CI: 1.19-5.41), and 7.47 (95%CI: 2.49-22.40) times more likely to have abnormal sural nerve amplitudes, respectively, compared to participants with normal examinations. Abnormalities in vibration and monofilament examinations are associated with abnormal sural nerve amplitudes and are useful in identifying CIPN

    Iron and iron-responsive proteins in the cardiomyopathy of Friedreich's ataxia

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    Abstract Hypertrophic cardiomyopathy is a common complication of Friedreich's ataxia (FRDA). Histological sections reveal abnormal cardiomyocytes, muscle fiber necrosis, reactive inflammation, and increased endomysial connective tissue. Scattered muscle fibers display perinuclear collections of minute iron-positive granules that lie in rows between myofibrils. Frataxin deficiency in FRDA causes mitochondrial iron dysmetabolism. We studied total iron and the iron-related proteins ferritin, mitochondrial ferritin, divalent metal transporter 1 (DMT1), and ferroportin in FRDA hearts by biochemical and histological techniques. Total iron in the left ventricular wall of FRDA patients (30.7¡19.3 mg/100 g dry weight) was not significantly higher than normal (31.3¡24.1 mg/100 g dry weight). Similarly, cytosolic holoferritin levels in FRDA hearts (230¡172 mg/g wet weight) were not significantly elevated above normal (148¡86 mg/g wet weight). The iron-positive granules exhibited immunoreactivity for cytosolic ferritin, mitochondrial ferritin, and ferroportin. Electron microscopy showed enhanced electron density of mitochondrial deposits after treatment with bismuth subnitrate supporting ferritin accumulation. The inflammatory cells in the endomysium were reactive for CD68, cytosolic ferritin, and the DMT1 isoform(s) translated from messenger ribonucleic acids containing iron-responsive elements (DMT1+). Progressive cardiomyopathy in FRDA is the likely result of iron-catalyzed mitochondrial damage followed by muscle fiber necrosis and a chronic reactive myocarditis

    Childhood obesity : genetic and environmental overlap with normal-range BMI

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    Obesity is the extreme of the same genetic and environmental factors responsible for variation throughout the distribution of BMI. This finding implies that genes that influence obesity will also be associated with BMI in the normal range, and similar environmental influences will affect BMI in the clinical and normal range. Knowing that obesity is influenced by the same genetic and environmental factors that affect weight at all levels has implications for investigating the mechanisms for weight gain and developing interventions for weight control
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