Publications by authors named "Mark Kellett"

This study explores the natural history of vestibular, trigeminal and lower cranial nerve schwannomas (VS, TS, LCNS) in patients with Neurofibromatosis type 2 (NF2), to understand how pathogenic variants (PVs) of the NF2 gene affect tumour burden and growth rate, via a retrospective analysis of a UK NF2 centre database and imaging. VS, TS and LCNS location and size were measured in accordance with a standardised protocol. PVs were categorised in accordance with the UK NF2 Genetic Severity Score (GSS).

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Article Synopsis
  • The study evaluates the occurrence of mosaicism in de novo neurofibromatosis 2 (NF2) among patients without known prior family history, testing over 1,000 individuals for NF2 variants using DNA from lymphocytes and tumors.
  • The findings show that 22% of patients exhibited proven or presumed mosaic NF2 variants, with the overall probable mosaicism rate estimated at nearly 60%, varying significantly with age.
  • The research concludes that NF2 likely has the highest mosaicism rate in nonlethal de novo dominant diseases, suggesting minimal risks to offspring that may be related to the variant frequencies found in the parents' blood.
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Article Synopsis
  • The study identifies deficiencies in the current diagnostic criteria for neurofibromatosis 2 (NF2) by analyzing two large patient databases.
  • Evidence suggests that terms like "glioma" and "neurofibroma" should be eliminated from the criteria, as they do not effectively contribute to diagnoses.
  • The term "ependymoma” showed a 100% positive predictive value, while individuals over 60 with bilateral vestibular schwannomas had low confirmation rates, indicating a need for updated criteria and genetic testing recommendations.
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Objectives/hypothesis: Unilateral vestibular schwannoma (VS) occurs with a lifetime risk of around 1 in 1,000 and is due to inactivation of the NF2 gene, either somatically or from a constitutional mutation. It has been postulated that familial occurrence of unilateral VS occurs more frequently than by chance, but no causal mechanism has been confirmed.

Study Design: Retrospective database analysis.

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Objectives: Schwannomatosis is a dominantly inherited condition predisposing to schwannomas of mainly spinal and peripheral nerves with some diagnostic overlap with neurofibromatosis-2 (NF2), but the underlying epidemiology is poorly understood. We present the birth incidence and prevalence allowing for overlap with NF2.

Methods: Schwannomatosis and NF2 cases were ascertained from the Manchester region of England (population=4.

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Article Synopsis
  • The study examined the occurrence of malignant peripheral nerve sheath tumors (MPNST) in patients with neurofibromatosis type 2 (NF2) using a database of 1253 NF2 patients.
  • Despite analyzing over 2000 cases of vestibular schwannomas, no spontaneous MPNST cases were found in unirradiated patients, although two patients developed MPNST after radiation treatment.
  • The conclusion indicates that NF2 patients should not be considered at heightened risk for malignant transformation of vestibular schwannomas unless they have received stereotactic radiosurgery, highlighting the need for larger studies to explore this potential link more thoroughly.
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Background: The Manchester criteria for neurofibromatosis type 2 (NF2) include a range of tumors, and gliomas were incorporated in the original description. The gliomas are now widely accepted to be predominantly spinal cord ependymomas.

Objective: To determine whether these gliomas include any cases of malignant glioma (WHO grade III and IV) through a database review.

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Background: We aimed to characterize the clinical and electrophysiological features of patients with slow orthostatic tremor.

Case Report: The clinical and neurophysiological data of patients referred for lower limb tremor on standing were reviewed. Patients with symptomatic or primary orthostatic tremor were excluded.

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Background & Aims: Dysphagia in patients with Parkinson's disease, persisting despite dopaminergic treatment, affects intake of nutrients and medication, and reduces quality of life (QOL). We investigated the neurophysiologic mechanisms that contribute to dysphagia in these patients, on and off L-3,4-dihydroxyphenylalanine (levodopa), using transcranial magnetic stimulation.

Methods: We studied 26 patients with Parkinson's disease (age, 65 ± 9 y; 10 men).

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Background: The antiepileptic drug topiramate reduces levodopa-induced dyskinesia without exacerbating parkinsonism in animal models. We report a randomized, double-blind, placebo-controlled crossover trial in patients with Parkinson's disease and levodopa-induced dyskinesia.

Methods: Fifteen patients with Parkinson's disease and stable levodopa-induced dyskinesia were enrolled into the study, of whom 13 were randomized to topiramate or placebo.

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We present the analysis of a prospective multicentre study to investigate genetic effects on the prognosis of newly treated epilepsy. Patients with a new clinical diagnosis of epilepsy requiring medication were recruited and followed up prospectively. The clinical outcome was defined as freedom from seizures for a minimum of 12 months in accordance with the consensus statement from the International League Against Epilepsy (ILAE).

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There is accumulating evidence for the benefits of exercise in Parkinson's disease (PD), but less is known about group exercise interventions. We evaluated the effect of gym-training programme on people with PD. Thirty-two adults with mild to moderate PD, not currently exercising formally, were randomised to an immediate 20-week biweekly gym training programme at a local leisure complex, or a 10-week programme starting 10 weeks later.

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Introduction: Itraconazole is an anti-fungal agent widely used to treat various forms of mycosis. It is particularly useful in allergic bronchopulmonary aspergillosis and severe asthma with fungal sensitization. Side effects are uncommon and usually mild.

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Background: Valproate is widely accepted as a drug of first choice for patients with generalised onset seizures, and its broad spectrum of efficacy means it is recommended for patients with seizures that are difficult to classify. Lamotrigine and topiramate are also thought to possess broad spectrum activity. The SANAD study aimed to compare the longer-term effects of these drugs in patients with generalised onset seizures or seizures that are difficult to classify.

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Background: Carbamazepine is widely accepted as a drug of first choice for patients with partial onset seizures. Several newer drugs possess efficacy against these seizure types but previous randomised controlled trials have failed to inform a choice between these drugs. We aimed to assess efficacy with regards to longer-term outcomes, quality of life, and health economic outcomes.

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Neuroferritinopathy is a progressive potentially treatable adult-onset movement disorder caused by mutations in the ferritin light chain gene (FTL1). Features overlap with common extrapyramidal disorders: idiopathic torsion dystonia, idiopathic Parkinson's disease and Huntington's disease, but the phenotype and natural history have not been defined. We studied a genetically homogeneous group of 41 subjects with the 460InsA mutation in FTL1, documenting the presentation, clinical course, biochemistry and neuroimaging.

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The coding region of the hsp68 gene has been amplified, cloned, and sequenced from 10 Drosophila species, 5 from the melanogaster subgroup and 5 from the montium subgroup. When the predicted amino acid sequences are compared with available Hsp70 sequences, patterns of conservation suggest that the C-terminal region should be subdivided according to predominant secondary structure. Conservation levels between Hsp68 and Hsp70 proteins were high in the N-terminal ATPase and adjacent beta-sheet domains, medium in the alpha-helix domain, and low in the C-terminal mobile domain (78%, 72%, 41%, and 21% identity, respectively).

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Opioid peptide transmission is enhanced in the striatum of animal models and Parkinson's disease (PD) patients with levodopa-induced motor complications. Opioid receptor antagonists reduce levodopa-induced dyskinesia in primate models of PD; however, clinical trials to date have been inconclusive. A double-blind, placebo controlled, crossover design study in 14 patients with PD experiencing motor fluctuations was carried out, using the non-subtype-selective opioid receptor antagonist naloxone.

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Cannabis may have medicinal uses in a variety of diseases. The neural mechanisms underlying dystonia involve abnormalities within the basal ganglia-in particular, overactivity of the lateral globus pallidus (GPl). Cannabinoid receptors are located presynaptically on GABA terminals within the GPi, where their activation reduces GABA reuptake.

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