Autoantibodies to N-methyl D-aspartate receptors in autoimmune encephalitis

N-methyl-D-aspartate receptor (NMDAR) antibody encephalitis is a recently described autoimmune encephalopathy defined by the presence of serum antibodies that bind NMDARs (NMDAR-Abs). NMDAR-Ab encephalitis is a severe, but treatmentresponsive encephalitis with subacute onset. It can be associated with tumours and affects mainly young adults. Patients present with cognitive dysfunction, seizures, psychiatric and sleep disorders and most develop dyskinesias, autonomic instability and reduced consciousness. To explore further the NMDAR-Abs and their potential pathogenicity, a series of in vitro investigations were performed and preliminary attempts at passive transfer of disease. Human embryonic kidney (HEK) cells transfected with the NR1 and NR2B subunits, and live cultured neurons, were used first to detect NMDAR-Ab binding. Immunocytochemistry and ow cytometry demonstrated that binding to transfected HEK cells could be improved when NMDAR were presented in clusters by cotransfection with the postsynaptic density protein PSD-95. The NR1 subunit was identified as the target of NMDAR-Abs, and a novel quantitative assay based on immunoprecipitation of NR1 tagged by fusion with green uorescent protein was developed. Measurement of NMDAR-Ab levels showed that antibody levels corresponded to the clinical disease score within individual patients. Although the purification of full length NR1 was not successful, a secreted N-terminal construct was created and expressed in HEK cells. The binding of NMDAR-Abs was confirmed and this construct will be used for active immunisation in future. To explore pathogenic mechanisms in vitro, the main antibody subclasses were shown to be IgG1 and IgG3. Moreover the patients' autoantibodies, but not healthy control antibodies, were able to activate the complement cascade in vitro in cell lines and primary cultures. Finally, the NMDAR-Abs were shown to bind to primary microglial cultures and to cause morphological changes corresponding to early activation processes after prolonged exposure. The research has developed new assays that could be used for diagnosis and serial studies and revealed new potential mechanisms in NMDAR-Ab encephalitis

Next generation sequencing for molecular diagnosis of neurological disorders using ataxias as a model

Many neurological conditions are caused by immensely heterogeneous gene mutations. The diagnostic process is often long and complex with most patients undergoing multiple invasive and costly investigations without ever reaching a conclusive molecular diagnosis. The advent of massively parallel, next-generation sequencing promises to revolutionize genetic testing and shorten the ‘diagnostic odyssey’ for many of these patients. We performed a pilot study using heterogeneous ataxias as a model neurogenetic disorder to assess the introduction of next-generation sequencing into clinical practice. We captured 58 known human ataxia genes followed by Illumina Next-Generation Sequencing in 50 highly heterogeneous patients with ataxia who had been extensively investigated and were refractory to diagnosis. All cases had been tested for spinocerebellar ataxia 1–3, 6, 7 and Friedrich’s ataxia and had multiple other biochemical, genetic and invasive tests. In those cases where we identified the genetic mutation, we determined the time to diagnosis. Pathogenicity was assessed using a bioinformatics pipeline and novel variants were validated using functional experiments. The overall detection rate in our heterogeneous cohort was 18% and varied from 8.3% in those with an adult onset progressive disorder to 40% in those with a childhood or adolescent onset progressive disorder. The highest detection rate was in those with an adolescent onset and a family history (75%). The majority of cases with detectable mutations had a childhood onset but most are now adults, reflecting the long delay in diagnosis. The delays were primarily related to lack of easily available clinical testing, but other factors included the presence of atypical phenotypes and the use of indirect testing. In the cases where we made an eventual diagnosis, the delay was 3–35 years (mean 18.1 years). Alignment and coverage metrics indicated that the capture and sequencing was highly efficient and the consumable cost was ∼£400 (€460 or US$620). Our pathogenicity interpretation pathway predicted 13 different mutations in eight different genes: PRKCG, TTBK2, SETX, SPTBN2, SACS, MRE11, KCNC3 and DARS2 of which nine were novel including one causing a newly described recessive ataxia syndrome. Genetic testing using targeted capture followed by next-generation sequencing was efficient, cost-effective, and enabled a molecular diagnosis in many refractory cases. A specific challenge of next-generation sequencing data is pathogenicity interpretation, but functional analysis confirmed the pathogenicity of novel variants showing that the pipeline was robust. Our results have broad implications for clinical neurology practice and the approach to diagnostic testing.</p

Next generation sequencing for molecular diagnosis of neurological disorders using ataxias as a model

Many neurological conditions are caused by immensely heterogeneous gene mutations. The diagnostic process is often long and complex with most patients undergoing multiple invasive and costly investigations without ever reaching a conclusive molecular diagnosis. The advent of massively parallel, next-generation sequencing promises to revolutionize genetic testing and shorten the ‘diagnostic odyssey’ for many of these patients. We performed a pilot study using heterogeneous ataxias as a model neurogenetic disorder to assess the introduction of next-generation sequencing into clinical practice. We captured 58 known human ataxia genes followed by Illumina Next-Generation Sequencing in 50 highly heterogeneous patients with ataxia who had been extensively investigated and were refractory to diagnosis. All cases had been tested for spinocerebellar ataxia 1–3, 6, 7 and Friedrich’s ataxia and had multiple other biochemical, genetic and invasive tests. In those cases where we identified the genetic mutation, we determined the time to diagnosis. Pathogenicity was assessed using a bioinformatics pipeline and novel variants were validated using functional experiments. The overall detection rate in our heterogeneous cohort was 18% and varied from 8.3% in those with an adult onset progressive disorder to 40% in those with a childhood or adolescent onset progressive disorder. The highest detection rate was in those with an adolescent onset and a family history (75%). The majority of cases with detectable mutations had a childhood onset but most are now adults, reflecting the long delay in diagnosis. The delays were primarily related to lack of easily available clinical testing, but other factors included the presence of atypical phenotypes and the use of indirect testing. In the cases where we made an eventual diagnosis, the delay was 3–35 years (mean 18.1 years). Alignment and coverage metrics indicated that the capture and sequencing was highly efficient and the consumable cost was ∼£400 (€460 or US$620). Our pathogenicity interpretation pathway predicted 13 different mutations in eight different genes: PRKCG, TTBK2, SETX, SPTBN2, SACS, MRE11, KCNC3 and DARS2 of which nine were novel including one causing a newly described recessive ataxia syndrome. Genetic testing using targeted capture followed by next-generation sequencing was efficient, cost-effective, and enabled a molecular diagnosis in many refractory cases. A specific challenge of next-generation sequencing data is pathogenicity interpretation, but functional analysis confirmed the pathogenicity of novel variants showing that the pipeline was robust. Our results have broad implications for clinical neurology practice and the approach to diagnostic testing.Copyright The Author (2013). Published by Oxford University Press on behalf of the Guarantors of Brain. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact [email protected]

Three wound-dressing strategies to reduce surgical site infection after abdominal surgery: the Bluebelle feasibility study and pilot RCT.

BACKGROUND Surgical site infection (SSI) affects up to 20% of people with a primary closed wound after surgery. Wound dressings may reduce SSI. OBJECTIVE To assess the feasibility of a multicentre randomised controlled trial (RCT) to evaluate the effectiveness and cost-effectiveness of dressing types or no dressing to reduce SSI in primary surgical wounds. DESIGN Phase A - semistructured interviews, outcome measure development, practice survey, literature reviews and value-of-information analysis. Phase B - pilot RCT with qualitative research and questionnaire validation. Patients and the public were involved. SETTING Usual NHS care. PARTICIPANTS Patients undergoing elective/non-elective abdominal surgery, including caesarean section. INTERVENTIONS Phase A - none. Phase B - simple dressing, glue-as-a-dressing (tissue adhesive) or 'no dressing'. MAIN OUTCOME MEASURES Phase A - pilot RCT design; SSI, patient experience and wound management questionnaires; dressing practices; and value-of-information of a RCT. Phase B - participants screened, proportions consented/randomised; acceptability of interventions; adherence; retention; validity and reliability of SSI measure; and cost drivers. DATA SOURCES Phase A - interviews with patients and health-care professionals (HCPs), narrative data from published RCTs and data about dressing practices. Phase B - participants and HCPs in five hospitals. RESULTS Phase A - we interviewed 102 participants. HCPs interpreted 'dressing' variably and reported using available products. HCPs suggested practical/clinical reasons for dressing use, acknowledged the weak evidence base and felt that a RCT including a 'no dressing' group was acceptable. A survey showed that 68% of 1769 wounds (727 participants) had simple dressings and 27% had glue-as-a-dressing. Dressings were used similarly in elective and non-elective surgery. The SSI questionnaire was developed from a content analysis of existing SSI tools and interviews, yielding 19 domains and 16 items. A main RCT would be valuable to the NHS at a willingness to pay of £20,000 per quality-adjusted life-year. Phase B - from 4 March 2016 to 30 November 2016, we approached 862 patients for the pilot RCT; 81.1% were eligible, 59.4% consented and 394 were randomised (simple,  = 133; glue,  = 129; no dressing,  = 132); non-adherence was 3 out of 133, 8 out of 129 and 20 out of 132, respectively. SSI occurred in 51 out of 281 participants. We interviewed 55 participants. All dressing strategies were acceptable to stakeholders, with no indication that adherence was problematic. Adherence aids and patients' understanding of their allocated dressing appeared to be key. The SSI questionnaire response rate overall was 67.2%. Items in the SSI questionnaire fitted a single scale, which had good reliability (test-retest and Cronbach's alpha of > 0.7) and diagnostic accuracy (-statistic = 0.906). The key cost drivers were hospital appointments, dressings and redressings, use of new medicines and primary care appointments. LIMITATIONS Multiple activities, often in parallel, were challenging to co-ordinate. An amendment took 4 months, restricting recruitment to the pilot RCT. Only 67% of participants completed the SSI questionnaire. We could not implement photography in theatres. CONCLUSIONS A main RCT of dressing strategies is feasible and would be valuable to the NHS. The SSI questionnaire is sufficiently accurate to be used as the primary outcome. A main trial with three groups (as in the pilot) would be valuable to the NHS, using a primary outcome of SSI at discharge and patient-reported SSI symptoms at 4-8 weeks. TRIAL REGISTRATION Phase A - Current Controlled Trials ISRCTN06792113; Phase B - Current Controlled Trials ISRCTN49328913. FUNDING This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in ; Vol. 23, No. 39. See the NIHR Journals Library website for further project information. Funding was also provided by the Medical Research Council ConDuCT-II Hub (reference number MR/K025643/1)