170,696 research outputs found
Public opposition to ecclesial involvement in secular politics: Schillebeeckx's grace-optimism as response to public theology and Radical Orthodoxy
No full textItem does not contain fulltextEdward Schillebeeckx 100: Grace, Governance and Globalization. Theology and Public Lif
Astrocytic pathology in Alpers’ syndrome
No full textRefractory epilepsy is the main neurological manifestation of Alpers’ syndrome, a severe childhood-onset mitochondrial disease caused by bi-allelic pathogenic variants in the mitochondrial DNA (mtDNA) polymerase gamma gene (POLG). The pathophysiological mechanisms underpinning neuronal hyperexcitabilty leading to seizures in Alpers’ syndrome remain unknown. However, pathological changes to reactive astrocytes are hypothesised to exacerbate neural dysfunction and seizure-associated cortical activity in POLG-related disease. Therefore, we sought to phenotypically characterise astrocytic pathology in Alpers’ syndrome. We performed a detailed quantitative investigation of reactive astrocytes in post-mortem neocortical tissues from thirteen patients with Alpers’ syndrome, eight neurologically normal controls and five sudden unexpected death in epilepsy (SUDEP) patients, to control for generalised epilepsy-associated astrocytic pathology. Immunohistochemistry to identify glial fibrillary acidic protein (GFAP)-reactive astrocytes revealed striking reactive astrogliosis localised to the primary visual cortex of Alpers’ syndrome tissues, characterised by abnormal-appearing hypertrophic astrocytes. Phenotypic characterisation of individual GFAP-reactive astrocytes demonstrated decreased abundance of mitochondrial oxidative phosphorylation (OXPHOS) proteins and altered expression of key astrocytic proteins including Kir4.1 (subunit of the inwardly rectifying K+ ion channel), AQP4 (astrocytic water channel) and glutamine synthetase (enzyme that metabolises glutamate). These phenotypic astrocytic changes were typically different from the pathology observed in SUDEP tissues, suggesting alternative mechanisms of astrocytic dysfunction between these epilepsies. Crucially, our findings provide further evidence of occipital lobe involvement in Alpers’ syndrome and support the involvement of reactive astrocytes in the pathogenesis of POLG-related disease
Central-peripheral sensory axonopathy in a juvenile case of Alpers-Huttenlocher disease
No full textPeripheral ataxia is reported in a juvenile case of Alpers-Huttenlocher disease (AHD). Neurophysiological and neuropathological investigations revealed a central-peripheral axonopathy, affecting the deep sensation carried by the peripheral nerve fibres and the posterior tracts of the cord, due to neuronal loss of the sensory ganglia. Involvement of the sensory pathways is regarded as a major feature of juvenile AHD
Central-peripheral sensory axonopathy in a juvenile case of Alpers-Huttenlocher disease
No full textPeripheral ataxiais reported in a juvenile case of Alpers-Huttenlocher disease (AHD). Neurophysiological and neuropathological investigations revealed a central-peripheral axonopathy, affecting the deep sensation carried by the peripheral nerve fibres and the posterior tracts of the cord, due to neuronal loss of the sensory ganglia. Involvement of the sensory pathways is regarded as a major feature of juvenile AHD
The NAD<sup>+</sup> precursor nicotinamide riboside rescues mitochondrial defects and neuronal loss in iPSC derived cortical organoid of Alpers' disease
No full textAlpers' syndrome is an early-onset neurodegenerative disorder usually caused by biallelic pathogenic variants in the gene encoding the catalytic subunit of polymerase-gamma (POLG), which is essential for mitochondrial DNA (mtDNA) replication. The disease is progressive, incurable, and inevitably it leads to death from drug-resistant status epilepticus. The neurological features of Alpers' syndrome are intractable epilepsy and developmental regression, with no effective treatment; the underlying mechanisms are still elusive, partially due to lack of good experimental models. Here, we generated the patient derived induced pluripotent stem cells (iPSCs) from one Alpers' patient carrying the compound heterozygous mutations of A467T (c.1399G>A) and P589L (c.1766C>T), and further differentiated them into cortical organoids and neural stem cells (NSCs) for mechanistic studies of neural dysfunction in Alpers' syndrome. Patient cortical organoids exhibited a phenotype that faithfully replicated the molecular changes found in patient postmortem brain tissue, as evidenced by cortical neuronal loss and depletion of mtDNA and complex I (CI). Patient NSCs showed mitochondrial dysfunction leading to ROS overproduction and downregulation of the NADH pathway. More importantly, the NAD+ precursor nicotinamide riboside (NR) significantly ameliorated mitochondrial defects in patient brain organoids. Our findings demonstrate that the iPSC model and brain organoids are good in vitro models of Alpers' disease; this first-in-its-kind stem cell platform for Alpers' syndrome enables therapeutic exploration and has identified NR as a viable drug candidate for Alpers' disease and, potentially, other mitochondrial diseases with similar causes.</p
Whole exome sequencing reveals mutations in NARS2 and PARS2, encoding the mitochondrial asparaginyl-tRNA synthetase and prolyl-tRNA synthetase, in patients with Alpers syndrome
No full textAlpers syndrome is a progressive neurodegenerative disorder that presents in infancy or early childhood and is characterized by diffuse degeneration of cerebral gray matter. While mutations in POLG1, the gene encoding the gamma subunit of the mitochondrial DNA polymerase, have been associated with Alpers syndrome with liver failure (Alpers-Huttenlocher syndrome), the genetic cause of Alpers syndrome in most patients remains unidentified. With whole exome sequencing we have identified mutations in NARS2 and PARS2, the genes encoding the mitochondrial asparaginyl-and prolyl-tRNA synthetases, in two patients with Alpers syndrome. One of the patients was homozygous for a missense mutation (c.641C>T, p.P214L) in NARS2. The affected residue is predicted to be located in the stem of a loop that participates in dimer interaction. The other patient was compound heterozygous for a one base insertion (c.1130dupC, p.K378 fs*1) that creates a premature stop codon and a missense mutation (c.836C>T, p.S279L) located in a conserved motif of unknown function in PARS2. This report links for the first time mutations in these genes to human disease in general and to Alpers syndrome in particular
Instructed threat enhances threat perception in faces
No full textAnxiety can boost the detection of potential threats in many ways. There is evidence that one and the same facial expression can be perceived differently depending on whether it is seen in a neutral or in a threatening situation. The present study investigated how aversive anticipation influences the accuracy of facial emotion recognition and the perceived emotional intensity of faces that had their objective emotional intensity manipulated. Forty-three participants categorized and rated the intensity of morphed faces (20%, 40%, 60%, and 80%) of fearful, angry, and happy expressions. Differently colored picture frames indicated either threat of electric shock or safety. Threat of shock enhanced the categorization accuracy specifically for fearful faces. During threat, 80% fearful and happy faces, and all levels of angry faces (20%-80%) were rated as more intense. In addition, we found that more trait-anxious individuals more frequently erroneously categorized neutral faces as fearful. Thus, state anxiety enhanced accurate fear categorization and boosted the perceived intensity of emotional faces, whereas trait anxiety led to a biased threat perception in nonthreatening faces. (PsycInfo Database Record (c) 2021 APA, all rights reserved)
Spatial variation of Anopheles-transmitted Wuchereria bancrofti and Plasmodium falciparum infection densities in Papua New Guinea.
No full textThe spatial variation of Wuchereria bancrofti and Plasmodium falciparum infection densities was measured in a rural area of Papua New Guinea where they share anopheline vectors. The spatial correlation of W. bancrofti was found to reduce by half over an estimated distance of 1.7 km, much smaller than the 50 km grid used by the World Health Organization rapid mapping method. For P. falciparum, negligible spatial correlation was found. After mass treatment with anti-filarial drugs, there was negligible correlation between the changes in the densities of the two parasites
POLG exon 22 skipping induced by different mechanisms in two unrelated cases of Alpers syndrome.
No full textInternational audienceThe POLG genes were sequenced in two unrelated patients presenting with Alpers syndrome. The novel c.3626_3629dupGATA and the c.3643+2T>C alleles were associated in trans with p.A467T and p.[W748S;E1143G], respectively. POLG transcripts from skin fibroblasts showed complete exon 22 skipping for patient 2, but surprisingly partial exon 22 skipping from the c.3626_3629dupGATA for patient 1. The creation of a putative exonic splicing silencer could be responsible for the splicing anomaly observed in patient 1. Both c.3643+2T>C and c.3626_3629dupGATA create a premature termination codon and a low polymerase γ activity in skin fibroblasts is responsible for the severe phenotype in these patients
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