P14.71 An assessment of the reporting and methodological quality of meningioma systematic reviews and meta-analyses

BACKGROUND

Systematic reviews and meta-analyses constitute the highest level of research evidence and for a disease with limited clinical trial activity, are often relied upon to help inform clinical practice. This review of reviews evaluates both the reporting & methodological quality of meningioma evidence syntheses.

MATERIAL AND METHODS

Potentially eligible meningioma reviews published between 1st January 1990 and 31st December 2020 were identified from eight electronic databases. Inclusion required the study to meet the Cochrane guideline definition of a systematic review or meta-analysis. Reviews concerning neurofibromatosis type 2, spinal and pediatric meningiomas were excluded. The reporting and methodological quality of articles were assessed against the following modified guidelines: Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA), A MeaSurement Tool to Assess Systematic Reviews (AMSTAR2) and the Risk of Bias in Systematic Reviews (ROBIS) guidelines.

RESULTS

117 systematic reviews were identified, 57 of which included meta-analysis (48.7%). The number of meningioma systematic reviews published each year has increased with 63 studies (53.9%) published between 01/2018 and 12/2020. A median of 17 studies (IQR 9–29) were included per review. Impact factor of journals publishing a systematic review with or without a meta-analysis was similar (median 2.3 vs 1.8, P=0.397). The mean PRISMA scores for systematic reviews with a meta-analysis was 21.11 (SD 4.1, 78% adherence) and without was 13.89 (SD 3.4, 63% adherence). Twenty-nine systematic reviews with meta-analysis (51%) and 11 without meta-analysis (18%) achieved greater than 80% adherence to PRISMA recommendations. Methodological quality assessment using AMSTAR2 revealed one study (0.9%) as high quality whilst 111 (94.8%) studies were graded as critically low. One hundred and two articles (87.2%) did not utilize a comprehensive search strategy as defined by the AMSTAR2 tool. Ninety-nine studies (84.6%) obtained a high level of concern for potential bias as per the ROBIS assessment. One hundred and eight articles (92.3%) failed to present information that a protocol had been established prior to study commencement and 76 articles (65.0%) did not conduct a risk of bias assessment. Across the three tools, domains relating to the establishment of a protocol prior to review commencement and conducting appropriate risk of bias assessments were frequently low scoring.

CONCLUSION

Overall reporting and methodological quality of meningioma systematic reviews was sub-optimal. Established critical appraisal tools and reporting guidelines should be utilized a priori to assist in producing high-quality systematic reviews.

OS09.7.A Quality of life outcomes in patients with incidental and operated meningiomas: the QUALMS study

BACKGROUND

Long-term Health-Related Quality of Life (HRQoL) is an important measure of patient wellbeing. There is a paucity of studies evaluating HRQoL in meningioma patients.

MATERIAL AND METHODS

Cross-sectional study of adult patients with an incidental or symptomatic intracranial meningioma. Patients with less than 5 years of follow-up, a history of craniospinal radiation or neurofibromatosis type 2 were excluded. HRQoL was evaluated with SF-36, EORTC QLQ-C30 and EORTC QLQ-BN20 questionnaires. Outcome determinants were evaluated using a multi-variable linear regression analysis, adjusted for patient, tumour and treatment characteristics, and duration of follow-up.

RESULTS

699 patients were invited to participate and 246 responded: 118 (48%) had an incidental meningioma. Mean age at diagnosis was 56.8 years (SD=13) and 81% were female. Median time from diagnosis to completion of questionnaire was 8.5 years (IQR 6.8–11.5). During follow-up, 158 patients (64.2%) had at least one operation for their meningioma and 47 patients (19.1%) had radiotherapy. Of those operated, 126 (79.7%) had WHO grade 1 and 24 (15.2%) had grade 2 meningiomas. Compared to normative population values, meningioma patients reported a worse SF-36 general health score (mean 61.9 vs 56.5, P=0.003) but a similar QLQ-C30 global health score (mean 62.3 vs 65.8, P=0.039), worse SF-36 and QLQ-C30 physical functioning scores (mean 74.1 vs 64.6, P<0.001 and mean 81.8 vs 76.5, P=0.007) and similar SF-36 and QLQ-C30 emotional health scores (mean 72.2 vs 70.9, P=0.367 and mean 71.0 vs 71.9, P=0.960). QLQ-C30 cognitive functioning was worse (mean 80.5 vs 71.4, P<0.001). Compared to the meningioma literature, QLQ-BN20 seizure burden was similar (mean 2.0 vs 1.6, P=0.760). A worse performance status at diagnosis was associated with an inferior QLQ-C30 global health score (β-coefficient=-4.9 [95% CI -9.1-(-)0.6] P=0.024). Number of surgeries was significantly associated with a worse QLQ-C30 cognitive functioning score (β-coefficient=-7.0 [95% CI -13.2-(-)0.9], P=0.025). Anti-epileptic drug use was associated with a significantly worse QLQ-C30 emotional health score (β-coefficient=-10.9 [95% CI -21.7-(-)0.01], P=0.050).

CONCLUSION

Meningioma patients have long-term HRQoL impairments affecting their physical and cognitive functions. An understanding that multiple surgeries affects cognitive function, and the need for anti-epileptic drugs equate to poorer emotional health, could help target appropriate therapies and support in the future.

P14.66 Re-operation for recurrent meningioma - are we helping patients?

BACKGROUND

Meningioma is the commonest primary brain tumour. Despite surgery, meningiomas can recur. Surgery is usually the first line treatment for recurrent meningioma. The aim was to determine the risk factors associated with clinical outcomes (performance status, morbidity, mortality, recurrence) following re-operation for recurrence of intracranial meningioma.

MATERIAL AND METHODS

Retrospective cohort study (1998–2018). Eligible patients had reoperation for local recurrence of a previously operated meningioma. Collected data included baseline clinical and imaging characteristic. Primary outcome measure was performance status after each reoperation. Secondary outcome measures were medical and surgical morbidity, recurrence-free survival (RFS) and overall survival (OS).

RESULTS

Fifty-eight patients were eligible (37 female, mean age at 1st re-operation 56.1 years (SD=11.6)). Eleven patients (19.6%) had 2 re-operations and 3 patients (5.4%) had 3 re-operations. Median follow up was 128.5 months (IQR=73–194.5). Median time to 1st recurrence and 1st re-operation were 36.5 (IQR=24.3–81.0) and 43.8 months (IQR=20.3–103.4), respectively. Fifteen patients (26.8%) had worse performance status after 1st reoperation, compared to 5.4% (n=3) after the primary operation. Complication rate was 32.1% (n=18) after the primary operation compared to 48.2% (n=27) after 1st reoperation. At primary operation, there were 29 (51.8%) grade 1, 24 (42.9%) grade 2, and 1 (1.8%) grade 3 tumours. Median RFS after first re-operation was 36.5 months (95% CI 29.3–43.9). Median OS was 312 months (95 % CI 257.8–366.2). Increased number of post-operative complications were a risk factor for worsened performance status following reoperation (OR 2.2 [95% CI 1.1–4.6], P=0.029).

CONCLUSION

Re-operation is associated with a worse performance status and increased risk of complications. Re-operating meningiomas for radiological recurrence without symptoms increases patient morbidity. Shared-care management decision should be made with patients when considering operating for radiological recurrence only.

P14.02 The Natural History of a Residual Intracranial Meningioma- Volumetric Growth and Predictors of Progression

BACKGROUND

Resection of meningioma leaves residual solid tumour in ~25% of patients. Selection for further treatment and follow-up strategy may benefit from knowledge of volumetric growth and associated prognostic factors.

MATERIAL AND METHODS

Growth rates were assessed using a linear mixed effects model, in a retrospective adult cohort that underwent subtotal resection of meningioma (2004–2018). Endpoints were re-treatment, end of follow-up or death. Cox regression analysis was used to identify prognostic factors for progression, defined using the Response Assessment in Neuro-Oncology (RANO) volumetric criteria.

RESULTS

236 patients were included. Mean age at surgery was 56.3 years (SD=13.7) and 73.7% were female. WHO grades were 1 (n=195, 82.6%), 2 (n=40, 16.9%) and 3 (n=1, 0.5%). Adjuvant fractionated radiotherapy (fRT) was administered to 34 patients (14.4%), with no propensity towards higher WHO grade or residual volume. Median pre-operative meningioma and post-operative residual volumes were 34.0cm3 (IQR 16.0–63.0) and 2.0cm3 (IQR 0.8–5.2), respectively. Median follow-up was 64 months (IQR 42–104). Median absolute growth rate (AGR) and relative growth rate (RGR) were 0.1cm3/year and 4.3%/year, respectively. According to RANO criteria, 132 (55.9%) patients progressed, of which 13 (9.8%) developed symptoms. Median progression-free survival was 56 months (95% CI 43.1–69.0). Multivariable analysis identified adjuvant fRT (HR 1.7, [95% CI 1.0–2.8], P=0.046), skull base location (HR 1.5, [95% CI 1.0–2.4], P=0.047) and Ki-67 index (HR 3.7 [95% CI 1.3–10.8], P=0.017) as prognostic factors for volumetric progression. WHO grade was not significant (HR 1.0, [95% CI 0.5–1.7], P=0.905). Forty-nine patients who progressed (37.1%) underwent further treatment: fRT (n=19), re-operation (n=15), Stereotactic radiosurgery (SRS) (n=10) and surgery+adjuvant fRT (n=5). Of those, 8 (16.3%) progressed further (after re-operation [n=6] and SRS [n=2]). Seven were treated with a 2nd re-operation (n=3), fRT (n=3), and SRS (n=1). One patient progressed after a 2nd reoperation and was treated with SRS, after which they remained stable. Median survival was not reached. 5- and 10-year overall survival (OS) was 96% and 86% respectively.

CONCLUSION

Growth rates of a residual meningioma vary with a dichotomy observed in progression rates. Half of patients with a residual meningioma showed radiological progression requiring multiple treatment to control the tumour. The other half demonstrate a more indolent course. Skull base location and higher Ki67 are important prognostic factors for progression and therefore, should be considered to stratify patients for adjuvant radiotherapy.

Volumetric growth of residual meningioma - A systematic review

Surgical resection of meningioma leaves residual solid tumour in over 25% of patients. Selection for further treatment and follow-up strategy may benefit from knowledge of volumetric growth and factors associated with re-growth. The aim of this review was to evaluate volumetric growth and variables associated with growth in patients that underwent incomplete resection of a meningioma without the use of adjuvant radiotherapy. A systematic review was conducted in accordance with the PRISMA statement and registered a priori with PROSPERO (registration number: CRD42020177052). Six databases were searched up to May 2020. Full text articles analysing volumetric growth rates in at least 10 patients who had residual meningioma after surgery were assessed. Four single-centre, retrospective studies totalling 238 patients were included, of which 99% of meningioma were WHO grade 1. The absolute tumour growth rate ranged from 0.09 to 4.94 cm³ per year. The relative growth rate ranged from 5.11 to 14.18% per year. Varying methods of volumetric assessment and definitions of growth impeded pooled analysis. Pre-operative and residual tumour volume, and hyperintensity on T2 weighted MRI were identified as variables associated with residual meningioma growth, however this was inconsistent across studies. Risk of bias was high in all studies. Radiological regrowth occurred in 42-67% of cases. Our review identified that volumetric growth of residual meningioma is scarcely reported. Sufficiently powered studies are required to delineate volumetric growth and prognostic factors to stratify management.

Lacosamide add-on therapy for focal epilepsy

BACKGROUND

This is an updated version of the Cochrane review published in 2015. Around half of people with epilepsy will not achieve seizure freedom on their first antiepileptic drug; many will require add-on therapy. Around a third of people fail to achieve complete seizure freedom despite multiple antiepileptic drugs. Lacosamide has been licenced as an add-on therapy for drug-resistant focal epilepsy.

OBJECTIVES

To evaluate the efficacy and tolerability of lacosamide as an add-on therapy for children and adults with drug-resistant focal epilepsy.

SEARCH METHODS

We searched the following databases (22 August 2019): the Cochrane Register of Studies (CRS Web), including the Cochrane Epilepsy Group Specialized Register and the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (Ovid, 1946 to 20 August 2019), ClinicalTrials.gov, and the WHO International Clinical Trials Registry Platform (ICTRP), with no language restrictions. We contacted UCB Pharma (sponsors of lacosamide).

SELECTION CRITERIA

Randomised controlled trials of add-on lacosamide in people with drug-resistant focal epilepsy.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methodology, assessing the following outcomes: 50% or greater reduction in seizure frequency; seizure freedom; treatment withdrawal; adverse events; quality of life; and cognitive changes. The primary analyses were intention-to-treat. We estimated summary risk ratios (RR) for each outcome presented with 99% confidence intervals (CI), except for 50% or greater seizure reduction, seizure freedom and treatment withdrawal which were presented with 95% CIs. We performed subgroup analyses according to lacosamide dose and sensitivity analyses according to population age, whereby data from children were excluded from the meta-analysis.

MAIN RESULTS

We included five trials (2199 participants). The risk of bias for all studies was low to unclear. All studies were placebo-controlled and assessed doses from 200 mg to 600 mg per day. One study evaluated lacosamide in children; all other studies were in adults. Trial duration ranged from 24 to 26 weeks. All studies used adequate methods of randomisation and were double-blind. Overall, the certainty of the evidence for the outcomes was judged as moderate to high, with the exception of seizure freedom which was low. The RR for a 50% or greater reduction in seizure frequency for all doses of lacosamide compared with placebo was 1.79 (95% CI 1.55 to 2.08; 5 studies; 2199 participants; high-certainty evidence). The RR for seizure freedom for all doses of lacosamide compared with placebo was 2.27 (95% CI 1.35 to 3.83; 5 studies; 2199 participants; low-certainty evidence). The RR for treatment withdrawal for all doses of lacosamide compared with placebo was 1.57 (95% CI 1.24 to 1.98; 5 studies; 2199 participants; moderate-certainty evidence). The estimated effect size for most outcomes did not change considerably following sensitivity analysis. For seizure freedom, however, the RR nearly doubled upon the exclusion of data from children (RR 4.04, 95% CI 1.52 to 10.73). Adverse events associated with lacosamide included: abnormal co-ordination (RR 6.12, 99% CI 1.35 to 27.77), blurred vision (RR 4.65, 99% CI 1.24 to 17.37), diplopia (RR 5.59, 99% CI 2.27 to 13.79), dizziness (RR 2.96, 99% CI 2.09 to 4.20), nausea (RR 2.35, 99% CI 1.37 to 4.02), somnolence (RR 2.04, 99% CI 1.22 to 3.41), vomiting (RR 2.94, 99% CI 1.54 to 5.64), and number of participants experiencing one or more adverse events (RR 1.12, 99% CI 1.01 to 1.24). Adverse events that were not significant were: vertigo (RR 3.71, 99% CI 0.86 to 15.95), rash (RR 0.58, 99% CI 0.17 to 1.89), nasopharyngitis (RR 1.41, 99% CI 0.87 to 2.28), headache (RR 1.34, 99% CI 0.90 to 1.98), fatigue (RR 2.11, 99% CI 0.92 to 4.85), nystagmus (RR 1.47, 99% CI 0.61 to 3.52), and upper respiratory tract infection (RR 0.70, 99% CI 0.43 to 1.15).

AUTHORS' CONCLUSIONS

Lacosamide is effective and well-tolerated in the short term when used as add-on treatment for drug-resistant focal epilepsy. Lacosamide increases the number of people with 50% or greater reduction in seizure frequency and may increase seizure freedom, compared to placebo. Higher doses of lacosamide may be associated with higher rates of adverse events and treatment withdrawal. Additional evidence is required assessing the use of lacosamide in children and on longer-term efficacy and tolerability.

The growth rate and clinical outcomes of radiation induced meningioma undergoing treatment or active monitoring

INTRODUCTION

Radiation induced meningioma (RIM) incidence is increasing in line with improved childhood cancer survival. No optimal management strategy consensus exists. This study aimed to delineate meningioma growth rates from tumor discovery and correlate with clinical outcomes.

METHODS

Retrospective study of patients with a RIM, managed at a specialist tertiary neuroscience center (2007-2019). Tumor volume was measured from diagnosis and at subsequent interval scans. Meningioma growth rate was determined using a linear mixed-effects model. Clinical outcomes were correlated with growth rates accounting for imaging and clinical prognostic factors.

RESULTS

Fifty-four patients (110 meningiomas) were included. Median duration of follow-up was 74 months (interquartile range [IQR], 41-102 months). Mean radiation dose was 41 Gy (standard deviation [SD] = 14.9) with a latency period of 34.4 years (SD = 13.7). Median absolute growth rate was 0.62 cm³/year and the median relative growth rate was 72%/year. Forty meningiomas (between 27 patients) underwent surgical intervention after a median follow-up duration of 4 months (IQR 2-35). Operated RIMs were clinically aggressive, likely to be WHO grade 2 at first resection (43.6%) and to progress after surgery (41%). Median time to progression was 28 months (IQR 13-60.5). A larger meningioma at discovery was associated with growth (HR 1.2 [95% CI 1.0-1.5], P = 0.039) but not progression after surgery (HR 2.2 [95% CI 0.7-6.6], P = 0.181). Twenty-seven (50%) patients had multiple meningiomas by the end of the study.

CONCLUSION

RIMs exhibit high absolute and relative growth rates after discovery. Surgery is recommended for symptomatic or rapidly growing meningiomas only. Recurrence risk after surgery is high.

Parameter inference for a stochastic kinetic model of expanded polyglutamine proteins

The presence of protein aggregates in cells is a known feature of many human age-related diseases, such as Huntington's disease. Simulations using fixed parameter values in a model of the dynamic evolution of expanded polyglutaime (PolyQ) proteins in cells have been used to gain a better understanding of the biological system. However, there is considerable uncertainty about the values of some of the parameters governing the system. Currently, appropriate values are chosen by ad hoc attempts to tune the parameters so that the model output matches experimental data. The problem is further complicated by the fact that the data only offer a partial insight into the underlying biological process: the data consist only of the proportions of cell death and of cells with inclusion bodies at a few time points, corrupted by measurement error. Developing inference procedures to estimate the model parameters in this scenario is a significant task. The model probabilities corresponding to the observed proportions cannot be evaluated exactly, and so they are estimated within the inference algorithm by repeatedly simulating realizations from the model. In general such an approach is computationally very expensive, and we therefore construct Gaussian process emulators for the key quantities and reformulate our algorithm around these fast stochastic approximations. We conclude by highlighting appropriate values of the model parameters leading to new insights into the underlying biological processes.

P79 Medical students’ mood adversely affected by COVID-19 pandemic: An interim analysis from the SPICE-19 prospective cohort study of 2075 medical students and interim foundation doctors

Background

Currently, we can only speculate on what the effects of the COVID-19 pandemic have been on medical students and interim foundation year doctors. In order to support them appropriately both now and, in the future, it is imperative that we understand the impact it has had upon them. This study assessed the effects of the COVID-19 pandemic on medical students and interim foundation year doctors across the United Kingdom (UK), and the support that they received and sought.

Methods

A prospective, observational, multicentre study was conducted. All medical students and interim foundation year doctors were eligible to participate. The data analysis was carried out as detailed a priori in the protocol.

Findings

A total of 2075 individuals participated in the SPICE-19 survey from 33 medical schools. There was a significant (p < 0.0001) decrease in participants’ mood when comparing their mood before the pandemic to during the pandemic. Social distancing and more time at home/with family were the factors that negatively and positively respectively impacted the mood of the greatest number of participants. All areas of life included in the survey were found to have been significantly more negatively impacted than positively impacted (p < 0.0001). 931 participants wanted more support from their university. Participants were mainly seeking support with exam preparation, course material, and financial guidance.

Discussion

Medical and foundation schools need to prepare adequate and effective support. If no action is taken, there may be a knock-on effect on workforce planning and the health of our future workforce. When medical students return to their universities, there is likely to be need for enhanced wellbeing support, adaptations in the short-term and long-term strategies for medical education, and provision of financial guidance.

Infant hydrocephalus: what valve first?

PURPOSE

To review the use of different valve types in infants with hydrocephalus, in doing so, determining whether an optimal valve choice exists for this patient cohort.

METHODS

We conducted (1) a literature review for all studies describing valve types used (programmable vs. non-programmable, valve size, pressure) in infants (≤ 2 years) with hydrocephalus, (2) a review of data from the pivotal BASICS trial for infant patients and (3) a separate, institutional cohort study from Alder Hey Children's Hospital NHS Foundation Trust. The primary outcome was any revision not due to infection.

RESULTS

The search identified 19 studies that were included in the review. Most did not identify a superior valve choice between programmable and non-programmable, small compared to ultra-small, and differential pressure compared to flow-regulating valves. Five studies investigated a single-valve type without a comparator group. The BASICS data identified 391 infants, with no statistically significant difference between gravitational and programmable subgroups. The institutional data from our tertiary referral centre did not reveal any significant difference in failure rate between valve subtypes.

CONCLUSION

Our review highlights the challenges of valve selection in infant hydrocephalus, reiterating that the concept of an optimal valve choice in this group remains a controversial one. While the infant-hydrocephalic population is at high risk of valve failure, heterogeneity and a lack of direct comparison between valves in the literature limit our ability to draw meaningful conclusions. Data that does exist suggests at present that there is no difference in non-infective failure rate are increasing in number, with the British valve subtypes in infant hydrocephalus, supported by both the randomised trial and institutional data in this study.

Gillespie C, Hennigan D, Bagga V, Mallucci C, Pettorini B. Efficacy and safety of the Miethke programmable differential pressure valve (proGAV®2.0): a single-centre retrospective analysis

PURPOSE

Achieving decompression without CSF over-drainage remains a challenge in hydrocephalus. Differential pressure valves are a popular treatment modality, with evidence suggesting that incorporation of gravitational units helps minimise over-drainage. This study seeks to describe the utility of the proGAV®2.0 programmable valve in a paediatric population.

METHODS

Clinical records and imaging of all patients fitted with proGAV®2.0 valves and Miethke fixed-pressure valves between 2014 and 2019 at our tertiary centre were analysed. Patient demographics, indication for shunt and valve insertion/revision and time to shunt/valve revision were collected. Ventricular linear metrics (fronto-occipital horn ratio (FOHR) and fronto-occipital horn width ratio (FOHWR)) were collected pre- and post-valve insertion. Microsoft Excel and SPSS v24 were used for data collection and statistical analysis.

RESULTS

Eighty-eight proGAV®2.0 valves were inserted in a population of 77 patients (n = 45 males (58%), mean age 5.1 years (IQR: 0.4-11.0 years)). A total of 102 Miethke fixed-pressure valves were inserted over the same time period. Median follow-up was 17.5 months (1.0-47.3). One (1.1%) proGAV®2.0 was revised due to over-drainage, compared to 2 (1.9%) fixed-pressure valves (p > 0.05). ProGAV®2.0 insertion resulted in a significant decrease in the mean number of revisions per patient per year (1.77 vs 0.25; p = 0.01). Overall shunt system survival with the proGAV®2.0 was 80.4% at 12 months, and mean time to revision was 37.1 months, compared to 31.0 months (95%CI: 25.7-36.3) and 58.3% in fixed-pressure valves (p < 0.01). Significant decreases were seen following proGAV®2.0 insertion in both FOHR and FOHWR, by 0.014 (95%CI: 0.006-0.023, p = 0.002) and 0.037 (95%CI: 0.005-0.069, p = 0.024) respectively.

CONCLUSION

The proGAV®2.0 provides effective decompression of hydrocephalic patients, significantly reduces the number of valve revisions per patient and had a significantly greater mean time to revision than fixed-pressure valves.

Survival of children following Nissen fundoplication

BACKGROUND

Analyses of survival after fundoplication in childhood are often restricted to 30-day mortality, or to the neurologically impaired. The objective of this study was to report actuarial survival and variables associated with mortality for all children undergoing fundoplication.

METHODS

This was a prospective observational study of fundoplication surgery by one surgeon; the endpoint was survival. Using a Cox proportional hazards model, gastrostomy, neurological status, tracheostomy, congenital cardiac disease, syndromic status, presence of congenital anomaly, other chronic disease, weight z-score at time of surgery, need for revisional fundoplication, use of laparoscopic surgery, gastric drainage procedures, age and sex were assessed for their influence on survival.

RESULTS

Two-hundred and thirty children underwent 255 fundoplications at a median age of 3·6 years. Forty-six children (20·0 per cent) died during a median follow-up of 2·8 (range 0·5-11·2) years. Statistical modelling showed gastrostomy (relative risk of death 11·04, P < 0·001), cerebral palsy (relative risk 6·58, P = 0·021) and female sex (relative risk 2·12, P = 0·015) to be associated with reduced survival. Revisional fundoplication was associated with improved survival (relative risk of death 0·37, P = 0·037). Survivors had significantly higher weight z-scores (-1·4 versus - 2·9 for those who died; P = 0·001). The 5-year survival rate after fundoplication for children with cerebral palsy and gastrostomy was 59 per cent.

CONCLUSION

Survival of children following fundoplication is related principally to the presence of a gastrostomy and neurological status. Estimates of children's life expectancy should take account of the poorer survival of neurologically impaired children who undergo fundoplication, presumably due to the related co-morbidities that lead to a gastrostomy.

Pattern recognition receptor expression is not impaired in patients with chronic mucocutanous candidiasis with or without autoimmune polyendocrinopathy candidiasis ectodermal dystrophy

Patients with chronic mucocutaneous candidiasis (CMC) have an unknown primary immune defect and are unable to clear infections with the yeast Candida. CMC includes patients with AIRE gene mutations who have autoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED), and patients without known mutations. CMC patients have dysregulated cytokine production, suggesting that defective expression of pattern recognition receptors (PRRs) may underlie disease pathogenesis. In 29 patients with CMC (13 with APECED) and controls, we assessed dendritic cell (DC) subsets and monocyte Toll-like receptor (TLR) expression in blood. We generated and stimulated monocyte-derived (mo)DCs with Candida albicans, TLR-2/6 ligand and lipopolysaccharide and assessed PRR mRNA expression by polymerase chain reaction [TLR-1-10, Dectin-1 and -2, spleen tyrosine kinase (Syk) and caspase recruitment domain (CARD) 9] in immature and mature moDCs. We demonstrate for the first time that CMC patients, with or without APECED, have normal blood levels of plasmocytoid and myeloid DCs and monocyte TLR-2/TLR-6 expression. We showed that in immature moDCs, expression levels of all PRRs involved in anti-Candida responses (TLR-1, -2, -4, -6, Dectin-1, Syk, CARD9) were comparable to controls, implying that defects in PRR expression are not responsible for the increased susceptibility to Candida infections seen in CMC patients. However, as opposed to healthy controls, both groups of CMC patients failed to down-regulate PRR mRNA expression in response to Candida, consistent with defective DC maturation, as we reported recently. Thus, impaired DC maturation and consequent altered regulation of PRR signalling pathways rather than defects in PRR expression may be responsible for inadequate Candida handling in CMC patients.

Modelling the checkpoint response to telomere uncapping in budding yeast

One of the DNA damage-response mechanisms in budding yeast is temporary cell-cycle arrest while DNA repair takes place. The DNA damage response requires the coordinated interaction between DNA repair and checkpoint pathways. Telomeres of budding yeast are capped by the Cdc13 complex. In the temperature-sensitive cdc13-1 strain, telomeres are unprotected over a specific temperature range leading to activation of the DNA damage response and subsequently cell-cycle arrest. Inactivation of cdc13-1 results in the generation of long regions of single-stranded DNA (ssDNA) and is affected by the activity of various checkpoint proteins and nucleases. This paper describes a mathematical model of how uncapped telomeres in budding yeast initiate the checkpoint pathway leading to cell-cycle arrest. The model was encoded in the Systems Biology Markup Language (SBML) and simulated using the stochastic simulation system Biology of Ageing e-Science Integration and Simulation (BASIS). Each simulation follows the time course of one mother cell keeping track of the number of cell divisions, the level of activity of each of the checkpoint proteins, the activity of nucleases and the amount of ssDNA generated. The model can be used to carry out a variety of in silico experiments in which different genes are knocked out and the results of simulation are compared to experimental data. Possible extensions to the model are also discussed.

Specific disruption of a schwann cell dystrophin-related protein complex in a demyelinating neuropathy

Dystroglycan-dystrophin complexes are believed to have structural and signaling functions by linking extracellular matrix proteins to the cytoskeleton and cortical signaling molecules. Here we characterize a dystroglycan-dystrophin-related protein 2 (DRP2) complex at the surface of myelin-forming Schwann cells. The complex is clustered by the interaction of DRP2 with L-periaxin, a homodimeric PDZ domain-containing protein. In the absence of L-periaxin, DRP2 is mislocalized and depleted, although other dystrophin family proteins are unaffected. Disruption of the DRP2-dystroglycan complex is followed by hypermyelination and destabilization of the Schwann cell-axon unit in Prx(-/-) mice. Hence, the DRP2-dystroglycan complex likely has a distinct function in the terminal stages of PNS myelinogenesis, possibly in the regulation of myelin thickness.

Peripheral demyelination and neuropathic pain behavior in periaxin-deficient mice

The Prx gene in Schwann cells encodes L- and S-periaxin, two abundant PDZ domain proteins thought to have a role in the stabilization of myelin in the peripheral nervous system (PNS). Mice lacking a functional Prx gene assemble compact PNS myelin. However, the sheath is unstable, leading to demyelination and reflex behaviors that are associated with the painful conditions caused by peripheral nerve damage. Older Prx-/- animals display extensive peripheral demyelination and a severe clinical phenotype with mechanical allodynia and thermal hyperalgesia, which can be reversed by intrathecal administration of a selective NMDA receptor antagonist We conclude that the periaxins play an essential role in stabilizing the Schwann cell-axon unit and that the periaxin-deficient mouse will be an important model for studying neuropathic pain in late onset demyelinating disease.

Transient expression of neurofascin by oligodendrocytes at the onset of myelinogenesis: implications for mechanisms of axon-glial interaction

Cell adhesion molecules (CAMs) must play a crucial role in both the initiation and signalling of axon-glial contact. However, the proteins that permit myelinating oligodendrocytes to recognize the axons that they ensheath in the developing CNS are unknown. By a subtractive cDNA library strategy, we have identified neurofascin as a powerful candidate for such a molecule. Neurofascin is strongly but transiently up-regulated in oligodendrocytes at the onset of myelinogenesis. Once oligodendrocytes have engaged their target axons the protein plays no further part, since the expression of the gene declines precipitously, in contrast to that of the major myelin component proteolipid protein, which remains elevated. After the initial surge of neurofascin expression in oligodendrocytes, there is a shift to a predominantly neuronal localization that persists into adulthood. Hence neurofascin in oligodendrocytes is unlikely to serve a function in the stabilization of the multilamellar sheath around the axon. The major neurofascin isoform of oligodendrocytes contains the third fibronectin type 3 (FNIII) repeat but lacks the mucin-like domain which supports the view that neurofascin isoforms are differentially expressed in the nervous system. Among the genes that are up-regulated during the terminal differentiation of the oligodendrocyte, neurofascin is unique in displaying a transient pattern of expression at the early stages of myelination. We propose that this CAM not only has a role in mediating axon recognition but also signals axonal contact through its links with the actin cytoskeleton.

Two PDZ domain proteins encoded by the murine periaxin gene are the result of alternative intron retention and are differentially targeted in Schwann cells

Periaxin was first described as a 147-kDa protein that was suggested to have a potential role in the initiation of myelin deposition in peripheral nerves based upon its abundance, cell type specificity, pattern of developmental expression, and localization (Gillespie, C. S., Sherman, D. L., Blair, G. E., and Brophy. P. J. (1994) Neuron 12, 497-508). Here we show that the murine periaxin gene spans 20.6 kilobases and encodes two mRNAs of 4.6 and 5.2 kilobases that encode two periaxin isoforms, L-periaxin and S-periaxin of 147 and 16 kDa respectively. The larger mRNA is produced by a retained intron mechanism that introduces a stop codon and results in a truncated protein with an intron-encoded C terminus of 21 amino acids. Both proteins possess a PDZ domain at the N terminus; nevertheless, they are targeted differently in Schwann cells. Like other proteins that contain PDZ domains, L-periaxin is localized to the plasma membrane of myelinating Schwann cells: in contrast, S-periaxin is expressed diffusely in the cytoplasm. This suggests that proteins that contain this protein-binding module may also participate in protein-protein interactions at sites other than the cell cortex.

Transient expression of the neurofilament proteins NF-L and NF-M by Schwann cells is regulated by axonal contact

Expression of the genes that encode neurofilament proteins is considered to be confined normally to neurons. However, in demyelinating peripheral nerves Schwann cells upregulate the mRNA for the medium-sized neurofilament protein (NF-M), and cultured Schwann cells of the myelin-forming phenotype can also synthesize and incorporate NF-M protein into their intermediate filament (IF) cytoskeleton. The purpose of this study was to establish how axonal contact might influence glial neurofilament gene expression and regulate the synthesis of neurofilament proteins. We show that the gene encoding NF-M is expressed at early stages of differentiation in myelin-forming Schwann cells in vivo; nevertheless, little NF-M protein can be detected in these cells. The transient induction of NF-M mRNA is also apparent in dedifferentiating Schwann cells during Wallerian degeneration. In these Schwann cells the mRNAs for NF-M and NF-L (the smallest polypeptide), but not NF-H (the largest neurofilament subunit), are coordinately expressed. In contrast to differentiating myelin-forming Schwann cells, the cells of degenerating nerves express both NF-M and NF-L polypeptides. Restoration of axonal contact in the growing nerve stimulates the recapitulation of Schwann cell differentiation including the elevation of NF-M and NF-L mRNA expression. These results demonstrate that the transient induction of neurofilament mRNAs in Schwann cells is a feature of both differentiation and dedifferentiation. However translation of these mRNAs is confined to Schwann cells deprived of axonal contact either by nerve injury or by culture in the absence of axons. These findings suggest that the expression of the NF-M and NF-L polypeptides is an important characteristic of those Schwann cells that will contribute to the repair of damaged peripheral nerves.

Periaxin, a novel protein of myelinating Schwann cells with a possible role in axonal ensheathment

We report the cloning and subcellular localization of a novel Schwann cell-specific protein of 147 kd that we have named periaxin. Periaxin has a remarkable domain of repetitive pentameric units in the primary sequence. It is expressed in the first uncompacted whorls of membrane that ensheathe the axon, and further synthesis of the protein in the rat sciatic nerve parallels the deposition of myelin. In mature myelin, periaxin colocalizes with the myelin-associated glycoprotein in the cytoplasm-filled periaxonal regions of the sheath but is excluded from compact myelin. We propose that periaxin has a role in axon-glial interactions, possibly by interacting with the cytoplasmic domains of integral membrane proteins such as myelin-associated glycoprotein in the periaxonal regions of the Schwann cell plasma membrane.

Schwann cells of the myelin-forming phenotype express neurofilament protein NF-M

Immature Schwann cells of the rat sciatic nerve can differentiate into myelin-forming or non-myelin-forming cells. The factors that influence this divergent development are unknown but certain markers such as galactocerebroside distinguish the two cell populations at an early stage of Schwann cell differentiation. Because myelination requires extensive changes in cell morphology, we have investigated the composition and structure of the Schwann cell cytoskeleton at a time when these cells become committed to myelination. Here we show that Schwann cells express a cytoskeletal protein of M(r) 145 before diverging into the myelin-forming path, i.e., before they acquire cell-surface galactocerobroside. The p145 protein has the characteristics of an intermediate filament (IF) protein and immunoelectron microscopy shows that it colocalizes with vimentin, which suggests that these two proteins can coassemble into IFs. Elevated intracellular cAMP levels, which can mimic some of the early effects of axons on Schwann cell differentiation, induced p145 synthesis, therefore, we conclude that myelin-forming Schwann cells express this protein at a very early stage in their development. Immunological comparisons with other IF proteins revealed a close similarity between p145 and the neurofilament protein NF-M; the identification of p145 as NF-M was confirmed by isolating and sequencing a full-length clone from a Schwann cell cDNA library. These data demonstrate that Schwann cells remodel their IFs by expressing NF-M before acquiring the myelin-forming phenotype and that IF proteins of the neurofilament-type are not restricted to neurons in the vertebrate nervous system.