Neurology

Cathepsin D gene and the risk of Alzheimer's disease: A population-based study and meta-analysis (Article)

Schuur, M. — 2011-09-01T00:00:00Z

Cathepsin D (CTSD) is a gene involved in amyloid precursor protein processing and is considered a candidate for Alzheimer's disease (AD). The aim of the current study was to examine if variation in CTSD increases the risk of AD. We performed a candidate-gene analysis in a population-based cohort study (N= 7983), and estimated the effect of CTSD on the risk of AD. Additionally, a large meta-analysis was performed incorporating our data and previously published data. The T-allele of CTSD rs17571 was associated with an increased risk of AD (p-value 0.007) in the Rotterdam Study. This association was predominantly found in APOE ε4 noncarriers. A meta-analysis of previously published data showed a significantly increased risk of AD in carriers of the T-allele of rs17571 (OR 1.22, 95% CI 1.03-1.44), irrespective of APOE ε4 carrier status. This study adds to the evidence that CTSD increases the risk of AD, although the effect size is moderate.

Strengthening the reporting of genetic risk prediction studies: The GRIPS statement (Article)

Janssens, A.C.J.W. — 2011-08-01T00:00:00Z

Strengthening the reporting of Genetic RIsk Prediction Studies (GRIPS): Explanation and elaboration (Article)

Janssens, A.C.J.W. — 2011-08-01T00:00:00Z

Validation of a new automated neonatal seizure detection system: A clinician's perspective (Article)

Cherian, P.J. — 2011-08-01T00:00:00Z

Objective: To validate an improved automated electroencephalography (EEG)-based neonatal seizure detection algorithm (NeoGuard) in an independent data set. Methods: EEG background was classified into eight grades based on the evolution of discontinuity and presence of sleep-wake cycles. Patients were further sub-classified into two groups; gpI: mild to moderate (grades 1-5) and gpII: severe (grades 6-8) EEG background abnormalities. Seizures were categorised as definite and dubious. Seizure characteristics were compared between gpI and gpII. The algorithm was tested on 756. h of EEG data from 24 consecutive neonates (median 25. h per patient) with encephalopathy and recorded seizures during continuous monitoring (cEEG). No selection was made regarding the quality of EEG or presence of artefacts. Results: Seizure amplitudes significantly decreased with worsening EEG background. Seizures were detected with a total sensitivity of 61.9% (1285/2077). The detected seizure burden was 66,244/97,574 s (67.9%). Sensitivity per patient was 65.9%, with a mean positive predictive value (PPV) of 73.7%. After excluding four patients with severely abnormal EEG background, and predominantly having dubious seizures, the algorithm showed a median sensitivity per patient of 86.9%, PPV of 89.5% and false positive rate of 0.28h-1. Sensitivity tended to be better for patients in gpI. Conclusions: The algorithm detects neonatal seizures well, has a good PPV and is suited for cEEG monitoring. Changes in electrographic characteristics such as amplitude, duration and rhythmicity in relation to deteriorating EEG background tend to worsen the performance of automated seizure detection. Significance: cEEG monitoring is important for detecting seizures in the neonatal intensive care unit (NICU). Our automated algorithm reliably detects neonatal seizures that are likely to be clinically most relevant, as reflected by the associated EEG background abnormality.

Incidence, treatment, and case-fatality of non-traumatic subarachnoid haemorrhage in the Netherlands (Article)

Risselada, R. — 2011-07-01T00:00:00Z

Background: Non-traumatic subarachnoid haemorrhage (SAH) is a devastating disorder and in the majority of cases it is caused by rupture of an intracranial aneurysm. No actual data are available on the incidence of non-traumatic SAH and aneursymal SAH (aSAH) in the Netherlands and little is known about treatment patterns of aSAH. Our purpose was therefore to assess the incidence, treatment patterns, and case-fatality of non-traumatic (a)SAH within the Dutch general population. Methods: Two population based data sources were used for this retrospective cohort study. One was the nationwide hospital discharge registry (National Medical Registration, LMR). Cases were patients hospitalized for SAH (ICD-9-code 430) in 2001-2005. The second source was the Integrated Primary Care Information (IPCI) database, a medical record database allowing for case validation. Cases were patients with validated non-traumatic (a)SAH in 1996-2006. Incidence, treatment, and case-fatality were assessed. Results: The incidence rate (IR) of non-traumatic SAH was 7.12 per 100,000 PY (95%CI: 6.94-7.31) and increased with age. The IR of aSAH was 3.78 (95%CI: 2.98-4.72). Women had a twofold increased risk of non-traumatic SAH; this difference appeared after the fourth decade. Non-traumatic SAH fatality was 30% (95%CI: 29-31%). Of aSAH patients 64% (95%CI: 53-74%) were treated with a clipping procedure, and 26% (95%CI: 17-37%) with coiling. Conclusion: Non-traumatic SAH is a rare disease with substantial case-fatality; rates in the Netherlands are similar to other countries. Case-fatality is also similar as well as age and sex patterns in incidence.

Alpha-internexin expression predicts outcome in anaplastic oligodendroglial tumors and may positively impact the efficacy of chemotherapy (Article)

Mokhtari, K. — 2011-07-01T00:00:00Z

BACKGROUND: Although it has been demonstrated that the neuronal intermediate filament alpha-internexin (INA) is closely related to 1p19q codeletion in gliomas, its prognostic and predictive value has not yet been confirmed in a prospective trial. The authors of this report assessed the prognostic significance of INA expression and its correlation with relevant clinical and molecular characteristics in the prospective, randomized European Organization for Research and Treatment of Cancer (EORTC) 26951 trial of adjuvant procarbazine, lomustine, and vincristine (PCV) in patients with anaplastic oligodendroglial tumors (AOTs). METHODS: INA immunohistochemistry expression in tumors from 92 patients who were included in the EORTC 26951 trial was analyzed independently by 2 observers and was correlated with relevant clinical characteristics, including progression-free survival (PFS) and overall survival (OS), and with molecular features, including 1p/19q codeletion, isocitrate dehydrogenase 1 and 2 gene (IDH1/IDH2) mutation, and O-6 methylguanine-DNA methyltransferase (MGMT) promoter methylation status. RESULTS: INA expression was observed in 33 tumors and was strongly correlated with 1p/19q codeletion, IDH1 mutations, and MGMT promoter methylation. It was associated with significantly better PFS and OS independent of the treatment received. By using Cox proportional hazard modeling for OS with stepwise selection, INA expression, patient age, and performance status were identified as independent prognostic factors. The results indicated that INA expression may have an impact on the efficacy of combined radiotherapy plus PCV. CONCLUSIONS: In a homogeneously treated group of patients with grade III AOTs, INA expression had strong favorable prognostic significance for OS and may have predictive value for sensitivity to chemotherapy. Copyright

Automated artifact removal as preprocessing refines neonatal seizure detection (Article)

Vos, M. de — 2011-06-27T00:00:00Z

Objective: The description and evaluation of algorithms using Independent Component Analysis (ICA) for automatic removal of ECG, pulsation and respiration artifacts in neonatal EEG before automated seizure detection. Methods: The developed algorithms decompose the EEG using ICA into its underlying sources. The artifact source was identified using the simultaneously recorded polygraphy signals after preprocessing. The EEG was reconstructed without the corrupting source, leading to a clean EEG. The impact of the artifact removal was measured by comparing the performance of a previously developed seizure detector before and after the artifact removal in 13 selected patients (9 having artifact-contaminated and 4 having artifact-free EEGs). Results: A significant decrease in false alarms (p = 0.01) was found while the Good Detection Rate (GDR) for seizures was not altered (p = 0.50). Conclusions: The techniques reduced the number of false positive detections without lowering sensitivity and are beneficial in long term EEG seizure monitoring in the presence of disturbing biological artifacts. Significance: The proposed algorithms improve neonatal seizure monitoring.

Fusion of metabolomics and proteomics data for biomarkers discovery: Case study on the experimental autoimmune encephalomyelitis (Article)

Blanchet, L. — 2011-06-22T00:00:00Z

Background: Analysis of Cerebrospinal Fluid (CSF) samples holds great promise to diagnose neurological pathologies and gain insight into the molecular background of these pathologies. Proteomics and metabolomics methods provide invaluable information on the biomolecular content of CSF and thereby on the possible status of the central nervous system, including neurological pathologies. The combined information provides a more complete description of CSF content. Extracting the full combined information requires a combined analysis of different datasets i.e. fusion of the data.Results: A novel fusion method is presented and applied to proteomics and metabolomics data from a pre-clinical model of multiple sclerosis: an Experimental Autoimmune Encephalomyelitis (EAE) model in rats. The method follows a mid-level fusion architecture. The relevant information is extracted per platform using extended canonical variates analysis. The results are subsequently merged in order to be analyzed jointly. We find that the combined proteome and metabolome data allow for the efficient and reliable discrimination between healthy, peripherally inflamed rats, and rats at the onset of the EAE. The predicted accuracy reaches 89% on a test set. The important variables (metabolites and proteins) in this model are known to be linked to EAE and/or multiple sclerosis.Conclusions: Fusion of proteomics and metabolomics data is possible. The main issues of high-dimensionality and missing values are overcome. The outcome leads to higher accuracy in prediction and more exhaustive description of the disease profile. The biological interpretation of the involved variables validates our fusion approach.

Effects of high-dose paracetamol on blood pressure in acute stroke (Article)

Hertog, H.M. den — 2011-06-10T00:00:00Z

den Hertog HM, van der Worp HB, van Gemert HMA, van Gijn J, Koudstaal PJ, Dippel DWJ. Effects of high-dose paracetamol on blood pressure in acute stroke., Acta Neurol Scand: DOI: 10.1111/j.1600-0404.2011.01529.x., © 2011 John Wiley & Sons A/S. Background- Early administration of paracetamol may improve outcome of patients with acute stroke and a baseline body temperature of 37°C or above by lowering body temperature and preventing fever. Besides its antipyretic effects, paracetamol may affect blood pressure through cyclooxygenase-2 inhibition. We therefore aimed to assess the effect of high-dose paracetamol on blood pressure in patients with acute stroke. Methods- We analyzed data of 540 patients admitted within 24h of stroke onset who were randomized to treatment with either paracetamol (6g daily) or placebo. Blood pressures were measured at 12, 24, and 48h from the start of treatment. Changes in blood pressure from baseline in the two treatment groups and corresponding 95% confidence intervals (CI) were calculated with linear regression analysis. Adjustments for potential confounders were made with a multiple linear regression model. Results- Treatment with high-dose paracetamol was associated with a significant reduction in systolic blood pressure of 4.5mm Hg (95% CI 0.6-8.5) at 12h from the start of treatment. This effect was no longer present after 24 and 48h. Conclusion- High-dose paracetamol reduces not only body temperature but also systolic blood pressure in the first 12h after start of treatment. Both effects may improve functional outcome after stroke, but this needs further study.

Survival and associated factors in 268 adults with Pompe disease prior to treatment with enzyme replacement therapy (Article)

Güngör, D. — 2011-06-03T00:00:00Z

Background: Pompe disease is a rare lysosomal storage disorder characterized by muscle weakness and wasting. The majority of adult patients have slowly progressive disease, which gradually impairs mobility and respiratory function and may lead to wheelchair and ventilator dependency. It is as yet unknown to what extent the disease reduces the life span of these patients. Our objective was to determine the survival of adults with Pompe disease not receiving ERT and to identify prognostic factors associated with survival. Methods. Data of 268 patients were collected in a prospective international observational study conducted between 2002 and 2009. Survival analyses from time of diagnosis and from time of study entry were performed using Kaplan-Meier curves and Cox-proportional-hazards regression. Results: Median age at study entry was 48 years (range 19-79 years). Median survival after diagnosis was 27 years, while median age at diagnosis was 38 years. During follow-up, twenty-three patients died prior to ERT, with a median age at death of 55 (range 23-77 years). Use of wheelchair and/or respiratory support and patients' score on the Rotterdam Handicap Scale (RHS) were identified as prognostic factors for survival. Five-year survival for patients without a wheelchair or respiratory support was 95% compared to 74% in patients who were wheelchair-bound and used respiratory support. In a Dutch subgroup of 99 patients, we compared the observed number of deaths to the expected number of deaths in the age- and sex-matched general population. During a median follow-up of 2.3 years, the number of deaths among the Dutch Pompe patients was higher than the expected number of deaths in the general population. Conclusion: Our study shows for the first time that untreated adults with Pompe disease have a higher mortality than the general population and that their levels of disability and handicap/participation are the most important factors associated with mortality. These results may be of relevance when addressing the effect of ERT or other potential treatment options on survival.

Response assessment in neuro-oncology (a report of the RANO group): Assessment of outcome in trials of diffuse low-grade gliomas (Article)

Bent, M.J. van den — 2011-06-01T00:00:00Z

Although low-grade gliomas (LGG) have a less aggressive course than do high-grade gliomas, the outcome of these tumours is ultimately fatal in most patients. Both the tumour and its treatment can cause disabling morbidity, particularly of cognitive functions. Because many patients present with seizures only, with no other signs and symptoms, maintenance of quality of life and function constitutes a particular challenge in LGG. The slow growth pattern of most LGG, and the rare radiological true responses despite a favourable clinical response to treatment, interferes with the use of progression-free survival as the primary endpoint in trials. Overall survival as an endpoint brings logistical challenges, and is sensitive to other non-investigational salvage therapies. Clinical trials for LGG need to consider other measures of patient benefit such as cognition, symptom burden, and seizure activity, to establish whether improved survival is reflected in prolonged wellbeing. This Review investigates clinical and imaging endpoints in trials of LGG, and provides response assessment in neuro-oncology (RANO) criteria for non-enhancing tumours. Additionally, other measures for patients with brain tumours that assess outcome are described. Similar considerations are relevant for trials of high-grade gliomas, although for these tumours survival is shorter and survival endpoints generally have more value than they do for LGG.

Serum IgG levels as biomarkers for optimizing IVIg therapy in CIDP (Article)

Doorn, P.A. van — 2011-06-01T00:00:00Z

Intravenous immunoglobulin (IVIg) is a proven effective treatment for chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) and Guillain-Barré syndrome (GBS). In GBS, patients show a large variability in serum immunoglobulin G (IgG) levels after standard IVIg treatment and a large increase in serum IgG levels (ÎIgG) was associated with a better outcome. Whether this is also the case in CIDP is not known. In contrast to GBS, most patients with CIDP need regular IVIg treatment for a prolonged period of time but the speed and magnitude of clinical response varies considerably between patients. Some patients with CIDP may need at least two IVIg courses before clinical signs of improvement become clear. At present, this clinical response is the only indicator used to adjust the IVIg dose and interval during maintenance treatment. Biomarkers reflecting disease activity or IVIg pharmacokinetics might be helpful to monitor patients and find the optimal dosage and frequency of IVIg treatment for individual patients. A recent prospective study in CIDP indicated that the increased ÎIgG after standard IVIg dosage during maintenance treatment was relatively constant within individual patients, but differed considerably between patients who were treated with the same stable dosage and interval of IVIg. Further studies are required to determine whether this variation in pharmacokinetics of IVIg is related with clinical recovery and whether IgG levels can be used as biomarkers to monitor and to adjust the optimal IVIg dosage in individual patients with CIDP.

Cytoreductive surgery of glioblastoma as the key to successful adjuvant therapies: New arguments in an old discussion (Article)

Stummer, W. — 2011-06-01T00:00:00Z

Background: This article discusses data from 3 randomized phase 3 trials, supporting a role for surgery in glioblastoma. Methods: Data were reviewed by extent of resection during primary surgery from the ALA-Glioma Study (fluorescence-guided versus conventional resection), the BCNU wafer study (BCNU wafer versus placebo), and the EORTC Study 26981-22981 (radiotherapy versus chemoradiotherapy with temozolomide). Results: For glioblastoma patients in the ALA study, median survival was 16.7 and 11.8 months for complete versus partial resection, respectively (P<0.0001). Survival effects were maintained after correction for differences in age and tumor location. For glioblastoma patients who received ≥90% resection in the BCNU wafer study, median survival increased for BCNU wafer versus placebo (14.5 versus 12.4 months, respectively; P=0.02), but no survival increase was found for <90% resection (11.7 versus 10.6 months, respectively; P=0.98). In the EORTC study, absolute median gain in survival with chemoradiotherapy versus radiotherapy was greatest for complete resections (+4.1 months; P=0.0001), compared with partial resections (+1.8 months; P=0.0001), or biopsies (+1.5 months; P=0.088), suggesting surgery enhanced adjuvant treatment. Conclusion: Complete resection appears to improve survival and may increase the efficacy of adjunct/adjuvant therapies. If safely achievable, complete resection should be the surgical goal for glioblastoma.

Ultrafast selective quantification of methotrexate in human plasma by high-throughput MALDI-isotope dilution mass spectrometry (Article)

Meesters, R.J.W. — 2011-06-01T00:00:00Z

Background: A new analytical MS method using isotope dilution combined with MALDI-triple quadrupole MS/MS has been developed and validated for the determination of methotrexate and 7-hydroxymethotrexate in plasma. Methotrexate, methotrexate-d3, 7-hydroxymethotrexate and 7-hydroxymethotrexate-d3 were monitored by selected reaction monitoring using the transitions m/z 455.2→308.2, 458.2→311.2, 471.2→324.2 and 474.2→327.2 for methotrexate, methotrexate-d3, 7-hydroxymethotrexate and 7-hydroxymethotrexate- d3, respectively. Results: The LLOQ was 1 nmol/l for methotrexate and 7-hydroxymethotrexate while the limit of detection was 0.3 nmol/l for both analytes. The new developed method was cross-validated by a fluorescence polarization immunoassay and tested for its clinical feasibility by measuring plasma samples from patients suffering from acute lymphoblastic leukemia. Plasma methotrexate concentrations ranged between 66.0 and 954 nmol/l and observed 7-hydroxymethotrexate/methotrexate ratios ranged between 0.1 and 32.4, respectively. Conclusion: The new method showed comparable analytical performances as the fluorescence polarization immunoassay, but analyte specificity and sensitivity of the newly developed method were significantly better.

Selective depletion of neuropathy-related antibodies from human serum by monolithic affinity columns containing ganglioside mimics (Article)

Tetala, K.K.R. — 2011-05-26T00:00:00Z

Monolithic columns containing ganglioside GM2 and GM3 mimics were prepared for selective removal of serum anti-ganglioside antibodies from patients with acute and chronic immune-mediated neuropathies. ELISA results demonstrated that anti-GM2 IgM antibodies in human sera and a mouse monoclonal anti-GM2 antibody were specifically and selectively adsorbed by monolithic GM2 mimic columns and not by blank monolithic columns or monolithic GM3 mimic columns. In control studies, serum antibodies against the ganglioside GQ1b from another neuropathy patient were not depleted by monolithic GM2 mimic columns. Fluorescence microscopy with FITC-conjugated anti-human immunoglobulin antibodies showed that the immobilized ganglioside mimics were evenly distributed along the column. The columns were able to capture ?95% of the anti-GM2 antibodies of patients after only 2 min of incubation. A monolithic column of 4.4 μL can deplete 28.2 μL of undiluted serum. These columns are potential diagnostic and therapeutic tools for neuropathies related to anti-ganglioside antibodies.

Strengthening the reporting of genetic risk prediction studies: the GRIPS statement. (Article)

Janssens, A.C.J.W. — 2011-05-16T00:00:00Z

The experimental autoimmune encephalomyelitis model for proteomic biomarker studies: From rat to human (Article)

Rosenling, T. — 2011-05-12T00:00:00Z

Multiple sclerosis (MScl) is defined by central nervous system (CNS) inflammation, demyelination and axonal damage. Some of the disease mechanisms are known but the cause of this complex disorder stays an enigma. Experimental autoimmune encephalomyelitis (EAE) is an animal model mimicking many aspects of MScl. This review aims to provide an overview over proteomic biomarker studies in the EAE model emphasizing the translational aspects with respect to MScl in humans.

Long-term follow-up and treatment in nine boys with X-linked creatine transporter defect (Article)

van de Kamp, J.M. — 2011-05-10T00:00:00Z

The creatine transporter (CRTR) defect is a recently discovered cause of X-linked intellectual disability for which treatment options have been explored. Creatine monotherapy has not proved effective, and the effect of treatment with L-arginine is still controversial. Nine boys between 8 months and 10 years old with molecularly confirmed CRTR defect were followed with repeated1H-MRS and neuropsychological assessments during 4-6 years of combination treatment with creatine monohydrate, L-arginine, and glycine. Treatment did not lead to a significant increase in cerebral creatine content as observed with H1-MRS. After an initial improvement in locomotor and personal-social IQ subscales, no lasting clinical improvement was recorded. Additionally, we noticed an age-related decline in IQ subscales in boys affected with the CRTR defect.

Value of EUS in Determining Curative Resectability in Reference to CT and FDG-PET: The Optimal Sequence in Preoperative Staging of Esophageal Cancer? (Article)

Schreurs, L.M.A. — 2011-05-06T00:00:00Z

Background: The separate value of endoscopic ultrasonography (EUS), multidetector computed tomography (CT), and18F-fluorodeoxyglucose positron emission tomography (FDG-PET) in the optimal sequence in staging esophageal cancer has not been investigated adequately. Methods: The staging records of 216 consecutive operable patients with esophageal cancer were reviewed blindly. Different staging strategies were analyzed, and the likelihood ratio (LR) of each module was calculated conditionally on individual patient characteristics. A logistic regression approach was used to determine the most favorable staging strategy. Results: Initial EUS results were not significantly related to the LRs of initial CT and FDG-PET results. The positive LR (LR+) of EUS-fine-needle aspiration (FNA) was 4, irrespective of CT and FDG-PET outcomes. The LR+ of FDG-PET varied from 13 (negative CT) to 6 (positive CT). The LR+ of CT ranged from 3-4 (negative FDG-PET) to 2-3 (positive FDG-PET). Age, histology, and tumor length had no significant impact on the LRs of the three diagnostic tests. Conclusions: This study argues in favor of PET/CT rather than EUS as a predictor of curative resectability in esophageal cancer. EUS does not correspond with either CT or FDG-PET. LRs of FDG-PET were substantially different between subgroups of negative and positive CT results and vice versa.

Dried blood spot UHPLC-MS/MS analysis of oseltamivir and oseltamivircarboxylate-a validated assay for the clinic (Article)

Hooff, G.P. — 2011-05-03T00:00:00Z

The neuraminidase inhibitor oseltamivir (Tamiflu®) is currently the first-line therapy for patients with influenza virus infection. Common analysis of the prodrug and its active metabolite oseltamivircarboxylate is determined via extraction from plasma. Compared with these assays, dried blood spot (DBS) analysis provides several advantages, including a minimum sample volume required for the measurement of drugs in whole blood. Samples can easily be obtained via a simple, non-invasive finger or heel prick. Mainly, these characteristics make DBS an ideal tool for pediatrics and to measure multiple time points such as those needed in therapeutic drug monitoring or pharmacokinetic studies. Additionally, DBS sample preparation, stability, and storage are usually most convenient. In the present work, we developed and fully validated a DBS assay for the simultaneous determination of oseltamivir and oseltamivircarboxylate concentrations in human whole blood. We demonstrate the simplicity of DBS sample preparation, and a fast, accurate and reproducible analysis using ultra high-performance liquid chromatography coupled to a triple quadrupole mass spectrometer. A thorough validation on the basis of the most recent FDA guidelines for bioanalytical method validation showed that the method is selective, precise, and accurate (≤15% RSD), and sensitive over the relevant clinical range of 5-1,500 ng/mL for oseltamivir and 20-1,500 ng/mL for the oseltamivircarboxylate metabolite. As a proof of concept, oseltamivir and oseltamivircarboxylate levels were determined in DBS obtained from healthy volunteers who received a single oral dose of Tamiflu®.