ORCID Profile
0000-0002-7667-9748
Current Organisations
Royal College of Physicians
,
University of Oxford
,
Oxford University Hospitals NHS Trust
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Publisher: eLife Sciences Publications, Ltd
Date: 24-01-2020
DOI: 10.7554/ELIFE.41836
Abstract: Neocortical-hippoc al interactions support new episodic (event) memories, but there is conflicting evidence about the dependence of remote episodic memories on the hippoc us. In line with systems consolidation and computational theories of episodic memory, evidence from model organisms suggests that the cornu ammonis 3 (CA3) hippoc al subfield supports recent, but not remote, episodic retrieval. In this study, we demonstrated that recent and remote memories were susceptible to a loss of episodic detail in human participants with focal bilateral damage to CA3. Graph theoretic analyses of 7.0-Tesla resting-state fMRI data revealed that CA3 damage disrupted functional integration across the medial temporal lobe (MTL) subsystem of the default network. The loss of functional integration in MTL subsystem regions was predictive of autobiographical episodic retrieval performance. We conclude that human CA3 is necessary for the retrieval of episodic memories long after their initial acquisition and functional integration of the default network is important for autobiographical episodic memory performance.
Publisher: Springer Science and Business Media LLC
Date: 19-05-2020
DOI: 10.1038/S41380-020-00899-W
Abstract: Serum neuronal autoantibodies, such as those to the NMDA receptor (NMDAR), are detectable in a subgroup of patients with psychotic disorders. It is not known if they are present before the onset of psychosis or whether they are associated with particular clinical features or outcomes. In a case–control study, sera from 254 subjects at clinical high risk (CHR) for psychosis and 116 healthy volunteers were tested for antibodies against multiple neuronal antigens implicated in CNS autoimmune disorders, using fixed and live cell-based assays (CBAs). Within the CHR group, the relationship between NMDAR antibodies and symptoms, cognitive function and clinical outcomes over 24 month follow-up was examined. CHR subjects were not more frequently seropositive for neuronal autoantibodies than controls (8.3% vs. 5.2% OR = 1.50 95% CI: 0.58–3.90). The NMDAR was the most common target antigen and NMDAR IgGs were more sensitively detected with live versus fixed CBAs ( p 0.001). Preliminary phenotypic analyses revealed that within the CHR s le, the NMDAR antibody seropositive subjects had higher levels of current depression, performed worse on the Rey Auditory Verbal Learning Task ( p 0.05), and had a markedly lower IQ ( p 0.01). NMDAR IgGs were not more frequent in subjects who later became psychotic than those who did not. NMDAR antibody serostatus and titre was associated with poorer levels of functioning at follow-up ( p 0.05) and the presence of a neuronal autoantibody was associated with larger amygdala volumes ( p 0.05). Altogether, these findings demonstrate that NMDAR autoantibodies are detectable in a subgroup of CHR subjects at equal rates to controls. In the CHR group, they are associated with affective psychopathology, impairments in verbal memory, and overall cognitive function: these findings are qualitatively and in idually similar to core features of autoimmune encephalitis and/or animal models of NMDAR antibody-mediated CNS disease. Overall the current work supports further evaluation of NMDAR autoantibodies as a possible prognostic biomarker and aetiological factor in a subset of people already meeting CHR criteria.
Publisher: Cold Spring Harbor Laboratory
Date: 05-12-2021
DOI: 10.1101/2021.12.03.21266112
Abstract: COVID-19 has been associated with many neurological complications including stroke, delirium and encephalitis. Furthermore, many in iduals experience a protracted post-viral syndrome which is dominated by neuropsychiatric symptoms, and is seemingly unrelated to COVID-19 severity. The true frequency and underlying mechanisms of neurological injury are unknown, but exaggerated host inflammatory responses appear to be a key driver of severe COVID-19 more broadly. We sought to investigate the dynamics of, and relationship between, serum markers of brain injury (neurofilament light [NfL], Glial Fibrillary Acidic Protein [GFAP] and total Tau) and markers of dysregulated host response including measures of autoinflammation (proinflammatory cytokines) and autoimmunity. Brain injury biomarkers were measured using the Quanterix Simoa HDx platform, cytokine profiling by Luminex (R& D) and autoantibodies by a custom protein microarray. During hospitalisation, patients with COVID-19 demonstrated elevations of NfL and GFAP in a severity-dependant manner, and there was evidence of ongoing active brain injury at follow-up 4 months later. Raised NfL and GFAP were associated with both elevations of pro-inflammatory cytokines and the presence of autoantibodies autoantibodies were commonly seen against lung surfactant proteins as well as brain proteins such as myelin associated glycoprotein, but reactivity was seen to a large number of different antigens. Furthermore, a distinct process characterised by elevation of serum total Tau was seen in patients at follow-up, which appeared to be independent of initial disease severity and was not associated with dysregulated immune responses in the same manner as NfL and GFAP.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 15-06-2021
Publisher: Wiley
Date: 11-2012
DOI: 10.1002/MDS.25169
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 05-02-2020
DOI: 10.1212/NXI.0000000000000674
Abstract: To compare the reproducibility of 11 antibody assays for immunoglobulin (Ig) G and IgM myelin oligodendrocyte glycoprotein antibodies (MOG-IgG and MOG-IgM) from 5 international centers. The following s les were analyzed: MOG-IgG clearly positive sera (n = 39), MOG-IgG low positive sera (n = 39), borderline negative sera (n = 13), clearly negative sera (n = 40), and healthy blood donors (n = 30). As technical controls, 18 replicates (9 MOG-IgG positive and 9 negative) were included. All s les and controls were recoded, aliquoted, and distributed to the 5 testing centers, which performed the following antibody assays: 5 live and 1 fixed immunofluorescence cell-based assays (CBA-IF, 5 MOG-IgG, and 1 MOG-IgM), 3 live flow cytometry cell-based assays (CBA-FACS, all MOG-IgG), and 2 ELISAs (both MOG-IgG). We found excellent agreement (96%) between the live CBAs for MOG-IgG for s les previously identified as clearly positive or negative from 4 different national testing centers. The agreement was lower with fixed CBA-IF (90%), and the ELISA showed no concordance with CBAs for detection of human MOG-IgG. All CBAs showed excellent interassay reproducibility. The agreement of MOG-IgG CBAs for borderline negative (77%) and particularly low positive (33%) s les was less good. Finally, most s les from healthy blood donors (97%) were negative for MOG-IgG in all CBAs. Live MOG-IgG CBAs showed excellent agreement for high positive and negative s les at 3 international testing centers. Low positive s les were more frequently discordant than in a similar comparison of aquaporin-4 antibody assays. Further research is needed to improve international standardization for clinical care.
Publisher: Wiley
Date: 11-2009
DOI: 10.1002/ANA.21807
Abstract: Encephalitis lethargica (EL) describes an encephalitis with psychiatric, sleep, and extrapyramidal movement disorders. Dyskinetic and parkinsonian forms have been described. EL shares clinical features with the anti-N-methyl-D-aspartate receptor (NMDAR-Ab) encephalitis. We studied 20 sera from pediatric patients with contemporary EL. Ten sera (from 2 males and 8 females, aged 1.3-13 years) and 6/6 cerebrospinal fluid s les were positive for NMDAR-Ab. NMDAR-Ab-positive patients had dyskinesias, agitation, seizures, and insomnia, whereas parkinsonism and somnolence dominated in the NMDAR-Ab-negative children. We were unable to identify any tumors. The dyskinetic form of EL is an NMDAR-Ab encephalitis and can affect very young children.
Publisher: Wiley
Date: 17-03-2011
DOI: 10.1002/ANA.22307
Abstract: To describe a distinctive seizure semiology that closely associates with voltage-gated potassium channel (VGKC)-complex/Lgi1 antibodies and commonly precedes the onset of limbic encephalitis (LE). Twenty-nine patients were identified by the authors (n = 15) or referring clinicians (n = 14). The temporal progression of clinical features and serum sodium, brain magnetic resonance imaging (MRI), positron emission tomography/single photon emission computed tomography, and VGKC-complex antibodies was studied. Videos and still images showed a distinctive adult-onset, frequent, brief dystonic seizure semiology that predominantly affected the arm and ipsilateral face. We have termed these faciobrachial dystonic seizures (FBDS). All patients tested during their illness had antibodies to VGKC complexes the specific antigenic target was Lgi1 in 89%. Whereas 3 patients never developed LE, 20 of the remaining 26 (77%) experienced FBDS prior to the development of the amnesia and confusion that characterize LE. During the prodrome of FBDS alone, patients had normal sodium and brain MRIs, but electroencephalography demonstrated ictal epileptiform activity in 7 patients (24%). Following development of LE, the patients often developed other seizure semiologies, including typical mesial temporal lobe seizures. At this stage, investigations commonly showed hyponatremia and MRI hippoc al high T2 signal functional brain imaging showed evidence of basal ganglia involvement in 5/8. Antiepileptic drugs (AEDs) were generally ineffective and in 41% were associated with cutaneous reactions that were often severe. By contrast, immunotherapies produced a clear, and often dramatic, reduction in FBDS frequency. Recognition of FBDS should prompt testing for VGKC-complex/Lgi1 antibodies. AEDs often produce adverse effects treatment with immunotherapies may prevent the development of LE with its potential for cerebral atrophy and cognitive impairment.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 03-12-2020
DOI: 10.1212/NXI.0000000000000924
Abstract: Antibodies to myelin oligodendrocyte glycoprotein (MOG) are associated with CNS demyelination inclusive of optic neuritis (ON) and transverse myelitis (TM). To examine whether peripheral nervous system (PNS) involvement is associated with MOG antibody–associated disorders (MOGAD), we performed detailed characterization of an Australasian MOGAD cohort. Using a live cell–based assay, we diagnosed 271 adults with MOGAD (2013–2018) and performed detailed clinical and immunologic characterization on those with likely PNS involvement. We identified 19 adults with MOGAD and PNS involvement without prior TM. All patients had CNS involvement including ON (bilateral [n = 3], unilateral [n = 3], and recurrent [n = 7]), a cortical lesion (n = 1), meningoencephalitis (n = 1), and subsequent TM (n = 4). Clinical phenotyping and neurophysiology were consistent with acute inflammatory demyelinating polyneuropathy (n = 1), myeloradiculitis (n = 3), multifocal motor neuropathy (n = 1), brachial neuritis (n = 2), migrant sensory neuritis (n = 3), and paresthesia and/or radicular limb pain (n = 10). Onset MRI spine was consistent with myeloradiculitis with nerve root enhancement in 3/19 and normal in 16/19. Immunotherapy resulted in partial/complete PNS symptom resolution in 12/15 (80%) (steroids and/or IV immunoglobulin n = 9, rituximab n = 2, and plasmapheresis n = 1). We identified serum antibodies targeting neurofascin 155, contactin-associated protein 2, or GM1 in 4/16 patients with MOGAD PNS compared with 0/30 controls ( p = 0.01). There was no binding to novel cell surface antigens using an in vitro myelinating sensory neuronal coculture model. Myeloradiculitis, combined central and peripheral demyelination syndromes, and inflammatory neuropathies may be associated with MOGAD and may be immunotherapy responsive. We identified a subgroup who may have pathology mediated by coexistent autoantibodies.
Publisher: American Medical Association (AMA)
Date: 12-2018
Publisher: Oxford University Press (OUP)
Date: 06-09-2022
Abstract: COVID-19 is associated with neurological complications including stroke, delirium and encephalitis. Furthermore, a post-viral syndrome dominated by neuropsychiatric symptoms is common, and is seemingly unrelated to COVID-19 severity. The true frequency and underlying mechanisms of neurological injury are unknown, but exaggerated host inflammatory responses appear to be a key driver of COVID-19 severity. We investigated the dynamics of, and relationship between, serum markers of brain injury [neurofilament light (NfL), glial fibrillary acidic protein (GFAP) and total tau] and markers of dysregulated host response (autoantibody production and cytokine profiles) in 175 patients admitted with COVID-19 and 45 patients with influenza. During hospitalization, sera from patients with COVID-19 demonstrated elevations of NfL and GFAP in a severity-dependent manner, with evidence of ongoing active brain injury at follow-up 4 months later. These biomarkers were associated with elevations of pro-inflammatory cytokines and the presence of autoantibodies to a large number of different antigens. Autoantibodies were commonly seen against lung surfactant proteins but also brain proteins such as myelin associated glycoprotein. Commensurate findings were seen in the influenza cohort. A distinct process characterized by elevation of serum total tau was seen in patients at follow-up, which appeared to be independent of initial disease severity and was not associated with dysregulated immune responses unlike NfL and GFAP. These results demonstrate that brain injury is a common consequence of both COVID-19 and influenza, and is therefore likely to be a feature of severe viral infection more broadly. The brain injury occurs in the context of dysregulation of both innate and adaptive immune responses, with no single pathogenic mechanism clearly responsible.
Publisher: BMJ
Date: 21-07-2018
Publisher: BMJ
Date: 23-01-2017
Publisher: Wiley
Date: 21-07-2018
DOI: 10.1111/ENE.13721
Abstract: Antibodies to glycine receptors (GlyR‐Abs) were first defined in progressive encephalopathy with rigidity and myoclonus ( PERM ) but were subsequently identified in other clinical presentations. Our aim was to assess the clinical associations of all patients identified with GlyR‐Abs in Queensland, Australia, between April 2014 and May 2017 and to compare these to cases reported in the literature. A literature review identified the clinical features of all published GlyR‐Ab‐positive cases through online databases. A case series was undertaken via collection of clinical information from all patients diagnosed or known to immunology, pathology or neurological services in Queensland during the study period of 3 years. In all, 187 GlyR‐Ab‐positive cases were identified in the literature. The majority (47.6%) had PERM , 22.4% had epilepsy, but the remaining 30% included mixed phenotypes consisting of cerebellar ataxia, movement disorders, demyelination and encephalitis/cognitive dysfunction. By contrast, in our series of 14 cases, eight had clinical presentations consistent with seizures and epilepsy and only three cases had classical features of PERM . There was one case each of global fatiguable weakness with sustained clonus, laryngeal dystonia and movement disorder with hemiballismus and tics. The rate of response to immune therapy was similar in all groups. Antibodies to glycine receptors are linked to a spectrum of neurological disease. The results of the literature review and our case series suggest a greater relationship between GlyR‐Abs and epilepsy than previously reported.
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Sarosh Irani.