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Contains fulltext : 290088.pdf (Publisher’s version ) (Open Access)

01 juli 2023, Item does not contain fulltext

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Radboud University, 06 december 2021, Promotores : Verbeek, M.M., Klijn, C.J.M. Co-promotor : Kuiperij, H.B., Contains fulltext : 240241.pdf (Publisher’s version ) (Open Access)

Contains fulltext : 230119.pdf (Publisher’s version ) (Open Access)

Radboud University, 09 september 2021, Promotores : Verbeek, M.M., Bloem, B.R. Co-promotor : Kuiperij, H.B., Contains fulltext : 235911.pdf (Publisher’s version ) (Open Access), Parkinsonian disorders, like Parkinson’s disease, multiple system atrophy and progressive supranuclear palsy, are progressive and fatal diseases without any pharmacological treatment to slow or stop the neuronal loss that causes movement and cognitive impairment. At the early disease stage, symptoms of the various parkinsonian disorders largely overlap, turning the establishment of a correct diagnosis into a challenge. Providing an accurate diagnosis at an early stage to individuals could help them and their families to better understand the course of the diseases, life expectancy, future expectations, as well as costs for treatment. Currently, diagnosis of parkinsonian disorders is based on physical examination of motor and non-motor symptoms, imaging scans, such as MRI, and response to dopaminergic medication, but this does not always provide an accurate diagnosis at an early stage. Fluid biomarkers may offer a great potential to help clinicians to accurately establish an early diagnosis. In this thesis, we have focused on the identification and validation of such fluid biomarkers for parkinsonian disorders, especially at the early disease stage when the symptoms are overlapping and the diagnosis is a challenge. Our findings showed moderate to high diagnostic accuracy for novel individual biomarkers, and when they were included in panels, combining fluid and clinical assessments, we could reach even higher accuracy levels. To summarize, our studies support the development of fluid biomarkers for the discrimination of parkinsonian disorders. Parkinsonismen, zoals de ziekte van Parkinson, meervoudige systeematrofie, en progressieve supranucleaire paralyse, zijn bewegingsstoornissen met een progressief en fataal ziektebeloop. Er is op dit moment geen goede medische behandeling om het zenuwverlies in de hersenen, dat bewegings- en cognitieve stoornissen bij deze patiënten veroorzaakt, af te remmen of te stoppen. In het beginstadium van de ziekte vertonen de diverse pa

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Contains fulltext : 220539.pdf (Publisher’s version ) (Open Access), The amyloid-β 43 (Aβ43) peptide has been shown to be abundantly expressed in Alzheimer's disease plaques, whereas only relatively low levels have been demonstrated in cerebral amyloid angiopathy (CAA). To better understand this discrepant distribution, we studied various biochemical properties of Aβ43, in comparison with Aβ40 and Aβ42. We assessed the interaction of Aβ43 with the three apoE isoforms (apoE2, apoE3, and apoE4) using SDS-PAGE/Western blotting and ELISA, aggregation propensity using thioflavin T assays, and cytotoxicity towards cerebrovascular cells using MTT assays. We found that Aβ43 did not differ from Aβ42 in its interaction with apoE, whereas Aβ40 had a significantly lower degree of interaction with apoE. At a molar ratio of 1:100 (apoE:Aβ), all apoE isoforms were comparably capable of inhibiting aggregation of Aβ40 and Aβ42, but not Aβ43. All Aβ variants had a concentration-dependent negative effect on metabolic activity of cerebrovascular cells. However, the degree of this effect differed for the three Aβ isoforms (Aβ40 > Aβ42 > Aβ43), with A�43 being the least cytotoxic peptide towards cerebrovascular cells. We conclude that Aβ43 has different biochemical characteristics compared with Aβ40 and Aβ42. Aggregation of Aβ43 is not inhibited by apoE, in contrast to the aggregation of Aβ40 and Aβ42. Furthermore, cerebrovascular cells are less sensitive towards Aβ43, compared with Aβ40 and Aβ42. In contrast, Aβ43 neither differed from Aβ42 in its aggregation propensity (in the absence of apoE) nor in its apoE-binding capacity. Altogether, our findings may provide an explanation for the lower levels of Aβ43 accumulation in cerebral vessel walls.

Contains fulltext : 226203.pdf (Publisher’s version ) (Open Access)

Contains fulltext : 217642.pdf (publisher's version ) (Open Access)

Radboud University, 22 oktober 2020, Promotores : Bloem, B.R., Gool, A.J. van Co-promotores : Verbeek, M.M., Kuiperij, H.B., Contains fulltext : 222331.pdf (publisher's version ) (Open Access)

Contains fulltext : 225773.pdf (Publisher’s version ) (Open Access), AIMS: We investigated the potential of apolipoprotein D (apoD) as cerebrospinal fluid (CSF) biomarker for cerebral amyloid angiopathy (CAA) after confirmation of its association with CAA pathology in human brain tissue. METHODS: The association of apoD with CAA pathology was analysed in human occipital lobe tissue of CAA (n = 9), Alzheimer's disease (AD) (n = 11) and healthy control cases (n = 11). ApoD levels were quantified in an age- and sex-matched CSF cohort of CAA patients (n = 31), AD patients (n = 27) and non-neurological controls (n = 67). The effects of confounding factors (age, sex, serum levels) on apoD levels were studied using CSF of non-neurological controls (age range 16-85 years), and paired CSF and serum samples. RESULTS: ApoD was strongly associated with amyloid deposits in vessels, but not with parenchymal plaques in human brain tissue. CSF apoD levels correlated with age and were higher in men than women in subjects >50 years. The apoD CSF/serum ratio correlated with the albumin ratio. When controlling for confounding factors, CSF apoD levels were significantly lower in CAA patients compared with controls and compared with AD patients (P = 0.0008). CONCLUSIONS: Our data show that apoD is specifically associated with CAA pathology and may be a CSF biomarker for CAA, but clinical application is complicated due to dependency on age, sex and blood-CSF barrier integrity. Well-controlled follow-up studies are required to determine whether apoD can be used as reliable biomarker for CAA.

Contains fulltext : 222194.pdf (publisher's version ) (Open Access)

Radboud University, 27 augustus 2020, Promotores : Verbeek, M.M., Klijn, C.J.M. Co-promotor : Kuiperij, H.B., Contains fulltext : 220180.pdf (publisher's version ) (Open Access)

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Contains fulltext : 207868.pdf (Publisher’s version ) (Open Access)

Item does not contain fulltext, BACKGROUND AND PURPOSE: Cerebral small vessel disease (SVD) is a frequent pathology in aging and contributor to the development of dementia. Plasma Abeta (amyloid beta) levels may be useful as early biomarker, but the role of plasma Abeta in SVD remains to be elucidated. We investigated the association of plasma Abeta levels with severity and progression of SVD markers. METHODS: We studied 487 participants from the RUN DMC study (Radboud University Nijmegen Diffusion Tensor and Magnetic Resonance Imaging Cohort) of whom 258 participants underwent 3 MRI assessments during 9 years. We determined baseline plasma Abeta38, Abeta40, and Abeta42 levels using ELISAs. We longitudinally assessed volume of white matter hyperintensities semiautomatically and manually rated lacunes and microbleeds. We analyzed associations between plasma Abeta and SVD markers by ANCOVA adjusted for age, sex, and hypertension. RESULTS: Cross-sectionally, plasma Abeta40 levels were elevated in participants with microbleeds (mean, 205.4 versus 186.4 pg/mL; P<0.01) and lacunes (mean, 194.8 versus 181.2 pg/mL; P<0.05). Both Abeta38 and Abeta40 were elevated in participants with severe white matter hyperintensities (Abeta38, 25.3 versus 22.7 pg/mL; P<0.01; Abeta40, 201.8 versus 183.3 pg/mL; P<0.05). Longitudinally, plasma Abeta40 levels were elevated in participants with white matter hyperintensity progression (mean, 194.6 versus 182.9 pg/mL; P<0.05). Both Abeta38 and Abeta40 were elevated in participants with incident lacunes (Abeta38, 24.5 versus 22.5 pg/mL; P<0.05; Abeta40, 194.9 versus 181.2 pg/mL; P<0.01) and Abeta42 in participants with incident microbleeds (62.8 versus 60.4 pg/mL; P<0.05). CONCLUSIONS: Plasma Abeta levels are associated with both presence and progression of SVD markers, suggesting that Abeta pathology might contribute to the development and progression of SVD. Plasma Abeta levels might thereby serve as inexpensive and noninvasive measure for identifying individuals with increas

Background:To enhance the accuracy of clinical diagnosis for Alzheimer’s disease (AD), pre-mortem biomarkers have become increasingly important for diagnosis and for participant recruitment in disease-specific treatment trials. Cerebrospinal fluid (CSF) biomarkers provide a low-cost alternative to positron emission tomography (PET) imaging for in vivo quantification of different AD pathological hallmarks in the brains of affected subjects; however, consensus around the best platform, most informative biomarker and correlations across different methodologies are controversial. Objective:Assessing levels of Aβ-amyloid and tau species determined using three different versions of immunoassays, the current study explored the ability of CSF biomarkers to predict PET Aβ-amyloid (32 Aβ-amyloid–and 45 Aβ-amyloid+), as well as concordance between CSF biomarker levels and PET Aβ-amyloid imaging. Methods:Prediction and concordance analyses were performed using a sub-cohort of 77 individuals (48 healthy controls, 15 with mild cognitive impairment, and 14 with AD) from the Australian Imaging Biomarker and Lifestyle study of aging. Results:Across all three platforms, the T-tau/Aβ42 ratio biomarker had modestly higher correlation with SUVR/BeCKeT (ρ= 0.69–0.8) as compared with Aβ42 alone (ρ= 0.66–0.75). Differences in CSF biomarker levels between the PET Aβ-amyloid–and Aβ-amyloid+ groups were strongest for the Aβ42/Aβ40 and T-tau/Aβ42 ratios (p < 0.0001); however, comparison of predictive models for PET Aβ-amyloid showed no difference between Aβ42 alone and the T-tau/Aβ42 ratio. Conclusion:This study confirms strong concordance between CSF biomarkers and PET Aβ-amyloid status is independent of immunoassay platform, supporting their utility as biomarkers in clinical practice for the diagnosis of AD and for participant enrichment in clinical trials.

Item does not contain fulltext, Cerebrospinal fluid (CSF) biomarkers may support the diagnosis of Alzheimer's disease (AD). We studied if the diagnostic power of AD CSF biomarker concentrations, i.e., Abeta42, total tau (t-tau), and phosphorylated tau (p-tau), is affected by differences in lateral ventricular volume (VV), using CSF biomarker data and magnetic resonance imaging (MRI) scans of 730 subjects, from 13 European Memory Clinics. We developed a Matlab-algorithm for standardized automated segmentation analysis of T1 weighted MRI scans in SPM8 for determining VV, and computed its ratio with total intracranial volume (TIV) as proxy for total CSF volume. The diagnostic power of CSF biomarkers (and their combination), either corrected for VV/TIV ratio or not, was determined by ROC analysis. CSF Abeta42 levels inversely correlated to VV/TIV in the whole study population (Abeta42: r = -0.28; p < 0.0001). For CSF t-tau and p-tau, this association only reached statistical significance in the combined MCI and AD group (t-tau: r = -0.15; p-tau: r = -0.13; both p < 0.01). Correction for differences in VV/TIV improved the differentiation of AD versus controls based on CSF Abeta42 alone (AUC: 0.75 versus 0.81) or in combination with t-tau (AUC: 0.81 versus 0.91). In conclusion, differences in VV may be an important confounder in interpreting CSF Abeta42 levels.

Contains fulltext : 177831.pdf (publisher's version ) (Open Access), BACKGROUND: Before implementation in clinical practice, biomarker assays need to be thoroughly analytically validated. There is currently a strong interest in implementation of the ratio of amyloid-beta peptide 1-42 and 1-40 (Abeta42/Abeta40) in clinical routine. Therefore, in this study, we compared the analytical performance of six assays detecting Abeta40 in cerebrospinal fluid (CSF) in six laboratories according to a recently standard operating procedure (SOP) developed for implementation of ELISA assays for clinical routine. METHODS: Abeta40 assays of six vendors were validated in up to three centers per assay according to recently proposed international consensus validation protocols. The performance parameters included sensitivity, precision, dilutional linearity, recovery, and parallelism. Inter-laboratory variation was determined using a set of 20 CSF samples. In addition, test results were used to critically evaluate the SOPs that were used to validate the assays. RESULTS: Most performance parameters of the different Abeta40 assays were similar between labs and within the predefined acceptance criteria. The only exceptions were the out-of-range results of recovery for the majority of experiments and of parallelism by three laboratories. Additionally, experiments to define the dilutional linearity and hook-effect were not executed correctly in part of the centers. The inter-laboratory variation showed acceptable low levels for all assays. Absolute concentrations measured by the assays varied by a factor up to 4.7 for the extremes. CONCLUSION: All validated Abeta40 assays appeared to be of good technical quality and performed generally well according to predefined criteria. A novel version of the validation SOP is developed based on these findings, to further facilitate implementation of novel immunoassays in clinical practice.

Contains fulltext : 168259.pdf (publisher's version ) (Closed access), Analytical validation of a biomarker assay is essential before implementation in clinical practice can occur. In this study, we analytically validated the performance of assays detecting soluble amyloid-beta precursor protein (sAPP) alpha and beta in CSF in two laboratories according to previously standard operating procedures serving this goal. sAPPalpha and sAPPbeta ELISA assays from two vendors (IBL-international, Meso Scale Diagnostics) were validated. The performance parameters included precision, sensitivity, dilutional linearity, recovery, and parallelism. Inter-laboratory variation, biomarker comparison (sAPPalpha vs. sAPPbeta) and clinical performance was determined in three laboratories using 60 samples of patients with subjective memory complaints, Alzheimer's disease, or frontotemporal dementia. All performance parameters of the assays were similar between labs and within predefined acceptance criteria. The only exceptions were minor out-of-range results for recovery at low concentrations and, despite being within predefined acceptance criteria, non-comparability of the results for evaluation of the dilutional linearity and hook-effect. Based on the inter-laboratory correlation between Lab #1 and Lab #2, the IBL-international assays were more robust (sAPPalpha: r(2) = 0.92, sAPPbeta: r(2) = 0.94) than the Meso Scale Diagnostics (MSD) assay (sAPPalpha: r(2) = 0.70, sAPPbeta: r(2) = 0.80). Specificity of assays was confirmed using assay-specific peptide competitors. Clinical validation showed consistent results across the clinical groups in the different laboratories for all assays. The validated sAPP assays appear to be of sufficient technical quality and perform well. Moreover, the study shows that the newly developed standard operating procedures provide highly useful tools for the validation of new biomarker assays. A recommendation was made for renewed instructions to evaluate the dilutional linearity and hook-effect. We analytically validated the per

RU Radboud Universiteit, 18 april 2016, Promotor : Willemsen, M.A.A.P. Co-promotores : Verbeek, M.M., Kuiperij, H.B., Contains fulltext : 156500.pdf (publisher's version ) (Open Access)

Item does not contain fulltext, Cerebrospinal fluid (CSF) levels of d-serine were recently reported as a potential new biomarker for Alzheimer's disease (AD), showing a perfect distinction between AD patients and healthy controls. In this study, we aimed to confirm these results and extend these previous findings to dementia with Lewy bodies and frontotemporal dementia. d-Serine levels in CSF of 29 AD patients, 8 dementia with Lewy bodies patients, 14 frontotemporal dementia patients, and 28 nondemented controls were measured using ultra-high-performance liquid chromatography-tandem mass spectrometry. In contrast to previous findings, in our study CSF d-serine levels were only slightly increased in AD patients compared with controls. CSF d-serine in AD did not differ from other dementias and was also not correlated to mini-mental state examination-scores. Owing to the large overlap of d-serine levels, we conclude that CSF d-serine is neither a suitable biomarker for AD nor for cognitive decline.

Item does not contain fulltext, BACKGROUND: Frontotemporal dementia (FTD) is a heterogeneous disease both at the clinical, genetic, and pathobiological level. The underlying pathological spectrum (termed FTLD, frontotemporal lobar degeneration) is in most cases defined by accumulation of either tau (FTLD-tau) or TDP-43 proteins (FTLD-TDP). Biomarkers to differentiate these subtypes are not yet available, whereas these are essential requirements to study the natural course of disease and for homogeneous inclusion of patients in clinical studies. OBJECTIVE: To study if a combination of total (t-) and phosphorylated (p-)tau, and t-TDP-43 and p-TDP-43 proteins in cerebrospinal fluid (CSF) is suitable to discriminate FTLD-tau and FTLD-TDP subtypes. METHODS: We developed immunoassays for the quantification of t-TDP-43 and p-TDP-43 proteins and used commercially available assays for the quantification of t-tau and p-tau proteins. We quantified these proteins in ventricular CSF samples from neuropathologically defined FTLD-tau and FTLD-TDP cases to study the reflection of underlying brain pathology in CSF composition, and in lumbar CSF samples from FTLD-tau and FTLD-TDP patients to study the diagnostic potential of CSF biomarkers. RESULTS: In ventricular CSF, t-TDP-43 and t-tau levels, when combined into one model, were significantly different between neuropathologically-defined FTLD-tau and FTLD-TDP cases. In a pilot study using lumbar CSF, the p-tau/t-tau ratio, but not t-TDP-43 levels, were significantly different between FTLD-TDP and FTLD-tau patients. CONCLUSION: We conclude that with current available methods, CSF tau, rather than TDP-43 proteins, may have diagnostic value in the differentiation of FTLD patients with either tau or TDP-43 pathology.

Contains fulltext : 167945.pdf (publisher's version ) (Open Access), The identification of reliable biomarkers for Alzheimer's disease (AD) remains challenging. Recently, abnormal levels of microRNAs (miRNAs) miR-27a, miR-29a, miR-29b, and miR-125b in cerebrospinal fluid (CSF) of AD patients were reported. We aimed to confirm the biomarker potential of these miRNAs for AD diagnosis. Additionally, we examined the influence of blood contamination on CSF miRNA levels as potential confounding factor. We studied expression levels of the four miRNAs by quantitative PCR in CSF samples of AD patients and non-demented controls, and in blood-spiked CSF. Levels of miR-29a, but not of the other three miRNAs, were increased by a factor of 2.2 in CSF of AD patients. Spiking of small amounts of blood into CSF revealed that miR-27a and miR-29a, but not miR-125b levels were strongly influenced by the number of blood cells in the sample. In conclusion, miR-29a may be a candidate biomarker for AD, but only when used in cell-free CSF.

Item does not contain fulltext, MicroRNAs (miRNAs) regulate translational inhibition of proteins, but are also detected in body fluids, including cerebrospinal fluid (CSF), where they may serve as disease-specific biomarkers. Previously, we showed differential expression of miR-146a, miR-29a, and miR-125b in the CSF of Alzheimer's disease (AD) patients versus controls. In this study, we aim to confirm these findings by using larger, independent sample cohorts of AD patients and controls from three different centers. Furthermore, we aim to identify confounding factors that possibly arise using such a multicenter approach. The study was extended by including patients diagnosed with mild cognitive impairment due to AD, frontotemporal dementia and dementia with Lewy bodies. Previous results of decreased miR-146a levels in AD patients compared to controls were confirmed in one center. When samples from all three centers were combined, several confounding factors were identified. After controlling for these factors, we did not identify differences in miRNA levels between the different groups. However, we provide suggestions to circumvent various pitfalls when measuring miRNAs in CSF to improve future studies.

Item does not contain fulltext, Neuronal Cell Adhesion Molecule (NrCAM) is a proposed new cerebrospinal fluid (CSF) biomarker in Alzheimer's disease (AD). In this pilot study, we aimed to validate and extend previous results and measured NrCAM by ELISA in CSF of patients with AD, frontotemporal dementia, dementia with Lewy bodies, and non-demented controls. NrCAM levels were comparable in all groups, but correlated positively with total tau and phosphorylated tau levels. Furthermore, NrCAM had no significant additional diagnostic value when combined with amyloid-beta42, total tau, and phosphorylated tau proteins. Therefore, NrCAM is not a suitable CSF biomarker to differentiate between dementia groups.

Item does not contain fulltext, Amyloid-beta (Abeta) is the most prominent protein in Alzheimer's disease (AD) senile plaques. In addition, Abeta interacts with a variety of Abeta-associated proteins (AAPs), some of which can form complexes with Abeta and influence its clearance, aggregation or toxicity. Identification of novel AAPs may shed new light on the pathophysiology of AD and the metabolic fate of Abeta. In this study, we aimed to identify new AAPs by searching for proteins that may form soluble complexes with Abeta in CSF, using a proteomics approach. We identified the secreted Wnt pathway protein Dickkopf-related protein 3 (Dkk-3) as a potential Abeta-associated protein. Using immunohistochemistry on human AD brain tissue, we observed that (i) Dkk-3 co-localizes with Abeta in the brain, both in diffuse and classic plaques. (ii) Dkk-3 is expressed in neurons and in blood vessel walls in the brain and (iii) is secreted by leptomeningeal smooth muscle cells in vitro. Finally, measurements using ELISA revealed that (iv) Dkk-3 protein is abundantly present in both cerebrospinal fluid and serum, but its levels are similar in non-demented controls and patients with AD, Lewy body dementia, and frontotemporal dementia. Our study demonstrates that Dkk-3 is a hitherto unidentified Abeta-associated protein which, given its relatively high cerebral concentrations and co-localization with Abeta, is potentially involved in AD pathology. In this study, we propose that Dickkopf-related protein-3 (Dkk-3) might be a novel Amyloid-beta (Abeta) associated protein. We demonstrate that Dkk-3 is expressed in the brain, especially in vessel walls, and co-localizes with Abeta in senile plaques. Furthermore, Dkk-3 levels in cerebrospinal fluid strongly correlate with Abeta40 levels, but were not suitable to discriminate non-demented controls and patients with dementia.

Contains fulltext : 152150.pdf (publisher's version ) (Open Access), Publisher: Abstract available from the publisher. Dut

Contains fulltext : 154315.pdf (publisher's version ) (Closed access), Decreased cerebral protein and activity levels of glutamine synthetase (GS) have been reported for Alzheimer's disease (AD) patients. Using a recently established method, we quantified total GS levels in cerebrospinal fluid (CSF) from AD patients and control subjects. Furthermore, we investigated if total GS levels in CSF could differentiate AD from frontotemperal dementia and dementia with Lewy bodies patients. As we found no significantly altered total GS levels in any of the patient groups compared with control subjects, we conclude that levels of total GS in CSF have no diagnostic value for AD, dementia with Lewy bodies, or frontotemperal dementia.

Contains fulltext : 154693.pdf (publisher's version ) (Open Access)

Contains fulltext : 154779.pdf (publisher's version ) (Open Access), Biochemical markers have a central position in the diagnosis and management of patients in clinical medicine, and also in clinical research and drug development, also for brain disorders, such as Alzheimer's disease. The enzyme-linked immunosorbent assay (ELISA) is frequently used for measurement of low-abundance biomarkers. However, the quality of ELISA methods varies, which may introduce both systematic and random errors. This urges the need for more rigorous control of assay performance, regardless of its use in a research setting, in clinical routine, or drug development. The aim of a method validation is to present objective evidence that a method fulfills the requirements for its intended use. Although much has been published on which parameters to investigate in a method validation, less is available on a detailed level on how to perform the corresponding experiments. To remedy this, standard operating procedures (SOPs) with step-by-step instructions for a number of different validation parameters is included in the present work together with a validation report template, which allow for a well-ordered presentation of the results. Even though the SOPs were developed with the intended use for immunochemical methods and to be used for multicenter evaluations, most of them are generic and can be used for other technologies as well.

Item does not contain fulltext, Decreased levels of alpha-synuclein (aSyn) in cerebrospinal fluid (CSF) in Parkinson's disease and related synucleinopathies have been reported, however, not consistently in all cross-sectional studies. To test the performance of one recently released human-specific enzyme-linked immunosorbent assay (ELISA) for the quantification of aSyn in CSF, we carried out a round robin trial with 18 participating laboratories trained in CSF ELISA analyses within the BIOMARKAPD project in the EU Joint Program - Neurodegenerative Disease Research. CSF samples (homogeneous aliquots from pools) and ELISA kits (one lot) were provided centrally and data reported back to one laboratory for data analysis. Our study showed that although factors such as preanalytical sample handling and lot-to-lot variability were minimized by our study design, we identified high variation in absolute values of CSF aSyn even when the same samples and same lots of assays were applied. We further demonstrate that although absolute concentrations differ between laboratories the quantitative results are comparable. With further standardization this assay may become an attractive tool for comparing aSyn measurements in diverse settings. Recommendations for further validation experiments and improvement of the interlaboratory results obtained are given.

Contains fulltext : 138429.pdf (publisher's version ) (Closed access)

Contains fulltext : 127725.pdf (publisher's version ) (Closed access), Differential diagnosis between Parkinson's disease (PD) and multiple system atrophy (MSA) is difficult, particularly at early disease stages, but is important for therapeutic management. The protein DJ-1 is implicated in the pathology of PD but little is known about its involvement in MSA. We aimed to determine the diagnostic value of CSF DJ-1 and tau proteins for discriminating PD and MSA. DJ-1 and total tau levels were quantified in the CSF of 43 PD patients, 23 MSA patients and 30 non-neurological controls matched for age and gender. Patients were part of a study with a 3-year prospective design with extended case-review follow-up of up to 9 years, ensuring maximum accuracy of the clinical diagnosis. Our results showed that CSF DJ-1 levels could distinguish MSA from PD with a 78% sensitivity and 78% specificity (AUC = 0.84). The combination of DJ-1 and tau proteins significantly improved this discrimination to 82% sensitivity and 81% specificity to identify MSA from PD (AUC = 0.92). Our results highlight the potential benefits of a combination of DJ-1 and total tau as biomarkers for differential diagnosis of MSA and PD.

Item does not contain fulltext, MicroRNAs (miRNAs) are small, noncoding RNAs that function in complex networks to regulate protein expression. In the brain, they are involved in development and synaptic plasticity. In this study, we aimed to identify miRNAs with a differential expression in either hippocampus or cerebrospinal fluid (CSF) from Alzheimer's disease (AD) patients and age-matched nondemented control subjects using quantitative polymerase chain reaction. In hippocampus, we also differentiated between AD patients with an intermediate stage, according to Braak III/IV stage, and a late stage, characterized according to Braak VI stage. Eight selected miRNAs were analyzed in hippocampus, and the expression of miR-16, miR-34c, miR-107, miR-128a, and miR-146a were differentially regulated. In CSF, out of 8 selected miRNAs only miR-16 and miR-146a could be reliably detected. In addition, we identified an effect of blood contamination on the CSF levels of miR-16, miR-24, and miR-146a. For group comparisons, we therefore selected CSF samples absent of, or containing only low numbers of blood cells. Levels of miR-146a were significantly decreased in CSF of AD patients. In conclusion, the abnormal expression of several miRNAs in hippocampus of intermediate- and late-stage AD patients suggests their involvement in AD pathogenesis, and low levels of miR-146a in CSF were associated with AD.

Radboud Universiteit Nijmegen, 8 juli 2014, Promotor : Bloem, B.R. Co-promotores : Verbeek, M.M., Kuiperij, H.B., Contains fulltext : 127383.pdf (publisher's version ) (Open Access)

Item does not contain fulltext, Amyloid-beta (Abeta) deposits are important pathological hallmarks of Alzheimer's disease (AD). Abeta aggregates into fibrils; however, the intermediate oligomers are believed to be the most neurotoxic species and, therefore, are of great interest as potential biomarkers. Here, we have developed an enzyme-linked immunosorbent assay (ELISA) specific for Abeta oligomers by using the same capture and (labeled) detection antibody. The ELISA predominantly recognizes relatively small oligomers (10-25 kDa) and not monomers. In brain tissue of APP/PS1 transgenic mice, we found that Abeta oligomer levels increase with age. However, for measurements in human samples, pretreatment to remove human anti-mouse antibodies (HAMAs) was required. In HAMA-depleted human hippocampal extracts, the Abeta oligomer concentration was significantly increased in AD compared with nondemented controls. Abeta oligomer levels could also be quantified in pretreated cerebrospinal fluid (CSF) samples; however, no difference was detected between AD and control groups. Our data suggest that levels of small oligomers might not be suitable as biomarkers for AD. In addition, we demonstrate the importance of avoiding HAMA interference in assays to quantify Abeta oligomers in human body fluids.

1 september 2012, Item does not contain fulltext, Our objective was to investigate TDP-43 plasma levels in patients with amyotrophic lateral sclerosis (ALS). TDP-43 has been identified as a major component of protein inclusions in the brain of patients with ALS; mutations in the corresponding gene (TARDBP) have also been identified. Although increased TDP-43 levels have been reported in the cerebrospinal fluid, plasma levels have not yet been assessed in patients with ALS. TDP-43 levels were quantified by sandwich ELISA in plasma of 219 patients and 100 controls. In addition, we sequenced exon 6 of TARDBP, and performed longitudinal TDP-43 plasma measurements in a subset of patients. Results showed that TDP-43 plasma levels were significantly increased in patients with ALS (p = 0.023) and we found a positive correlation with age in patients and controls. Longitudinal measurements of TDP-43 plasma levels showed an increase in only one patient, with stable levels in five others. Three TARDBP variations were identified in the ALS group (1.7%), but the association with TDP-43 plasma levels was ambiguous. In conclusion, our data indicate that TDP-43 plasma levels may have potential as a marker for ALS. A genotype-phenotype relationship could not, however, be established in this cohort.