Plasma p-tau212 antemortem diagnostic performance and prediction of autopsy verification of Alzheimer's disease neuropathology.

Blood phosphorylated tau (p-tau) biomarkers, including p-tau217, show high associations with Alzheimer's disease (AD) neuropathologic change and clinical stage. Certain plasma p-tau217 assays recognize tau forms phosphorylated additionally at threonine-212, but the contribution of p-tau212 alone to AD is unknown. We developed a blood-based immunoassay that is specific to p-tau212 without cross-reactivity to p-tau217. Here, we examined the diagnostic utility of plasma p-tau212. In five cohorts (n = 388 participants), plasma p-tau212 showed high performances for AD diagnosis and for the detection of both amyloid and tau pathology, including at autopsy as well as in memory clinic populations. The diagnostic accuracy and fold changes of plasma p-tau212 were similar to those for p-tau217 but higher than p-tau181 and p-tau231. Immunofluorescent staining of brain tissue slices showed prominent p-tau212 reactivity in neurofibrillary tangles that co-localized with p-tau217 and p-tau202/205. These findings support plasma p-tau212 as a peripherally accessible biomarker of AD pathophysiology.

Psychometric evaluation of the 5-item Medication Adherence Report Scale questionnaire in persons with multiple sclerosis.

The 5-item Medication Adherence Report Scale (MARS-5) is a reliable and valid questionnaire for evaluating adherence in patients with asthma, hypertension, and diabetes. Validity has not been determined in multiple sclerosis (MS). We aimed to establish criterion validity and reliability of the MARS-5 in persons with MS (PwMS). Our prospective study included PwMS on dimethyl fumarate (DMF). PwMS self-completed the MARS-5 on the same day before baseline and follow-up brain magnetic resonance imaging (MRI) 3 and 9 months after treatment initiation and were graded as highly and medium adherent upon the 24-cut-off score, established by receiver operator curve analysis. Health outcomes were represented by relapse occurrence from the 1st DMF dispense till follow-up brain MRI and radiological progression (new T2 MRI lesions and quantitative analysis) between baseline and follow-up MRI. Criterion validity was established by association with the Proportion of Days Covered (PDC), new T2 MRI lesions, and Beliefs in Medicines questionnaire (BMQ). The reliability evaluation included internal consistency and the test-retest method. We included 40 PwMS (age 37.6 ± 9.9 years, 75% women), 34 were treatment-naive. No relapses were seen during the follow-up period but quantitative MRI analysis showed new T2 lesions in 6 PwMS. The mean (SD) MARS-5 score was 23.1 (2.5), with 24 PwMS graded as highly adherent. The higher MARS-5 score was associated with higher PDC (b = 0.027, P<0.001, 95% CI: (0.0134-0.0403)) and lower medication concerns (b = -1.25, P<0.001, 95% CI: (-1.93-(-0,579)). Lower adherence was associated with increased number (P = 0.00148) and total volume of new T2 MRI lesions (P = 0.00149). The questionnaire showed acceptable internal consistency (Cronbach α = 0.72) and moderate test-retest reliability (r = 0.62, P < 0.0001, 95% CI: 0.33-0.79). The MARS-5 was found to be valid and reliable for estimating medication adherence and predicting medication concerns in persons with MS.

Medication persistence among people with multiple sclerosis in Slovenia treated with dimethyl fumarate.

Objective: Multiple sclerosis is a chronic, demyelinating inflammatory disease of the central nervous system. Medication persistence is defined as an interval between the initiation and last dose of the applied medication and presents a useful surrogate marker of a stable disease course. This observational study aimed to evaluate medication persistence and discontinuation reasons in Slovenian people with multiple sclerosis treated with dimethyl fumarate.Methods: Our retrospective cohort study evaluated people with relapsing-remitting multiple sclerosis treated with dimethyl fumarate as an initial monotherapy or switched from injectable disease-modifying therapy medication between 2014 and 2021. Medication dispenses were extracted from the Slovenian National Institute of Public Health Outpatient Medication Database. The medication persistence criterion was based on the treatment gap. Patients exceeding a 60-day gap were considered nonpersistent. The median time to discontinuation was assessed using survival analyses. Considering discontinuation reasons, patients were further divided into safety and inefficacy groups. Due to the high probability of adverse effects, patients exceeding a 60-day gap were included in the safety group, but definite discontinuation reason remains unknown. The impact of covariates was evaluated by Cox regression.Results: A total of 269 patients were included (183 women, mean age 37 years). During the 7-year follow-up period, 123 (45.7%) patients discontinued treatment. The median time to discontinuation was 5.6 years. After 1, 2, and 5 years of treatment, 84%, 77%, and 57% of patients were found to be persistent, respectively. All patients older than 30 years (p = 0.0013) and among them, those in the inefficacy group (p = 0.037) were more likely to be persistent.Conclusions: The results of our study proved a high persistence rate among our patients. The most frequent discontinuation reason was gastrointestinal adverse effects. Medication persistence requires interventions in younger patients with an unstable disease course.

Medication adherence and health outcomes in persons with multiple sclerosis treated with dimethyl fumarate.

BACKGROUND: Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system that particularly affects people in their 30s. Oral disease-modifying therapy (DMT) offers a simple dosage form, good efficacy and safety. Dimethyl fumarate (DMF) is a frequently prescribed oral DMT medication worldwide. The aim of this study was to evaluate the impact of medication adherence on health outcomes in Slovenian persons with MS treated with DMF. METHODS: Our retrospective cohort study included persons with relapsing-remitting MS on DMF treatment. The medication adherence was evaluated by AdhereR software package using the proportion of days covered (PDC) measure. The threshold was set at 90%. Health outcomes after treatment initiation were represented by relapse occurrence, disability progression and occurrence of active (new T2 and T1/Gadolinium (Gd) enhancing) lesions between first two outpatient visits and first two brain magnetic resonance imaging (MRI), respectively. For each health outcome a separate multivariable regression model was built. RESULTS: The study included 164 patients. Their mean age (SD) was 36.7 (8.8) years, and the majority of patients were women (114 or 70%). Eighty-one patients were treatment naive. The mean (SD) PDC value was 0.942 (0.08) and 82% of patients were considered adherent above the 90% threshold. Older age (OR 1.06 per one year, P = 0.017, 95% CI (1.01-1.11)) and treatment naivety (OR 3.93, P = 0.004, 95% CI (1.64-10.4)) were related to higher adherence. In the 6-year follow-up period after DMF treatment initiation, 33 patients experienced a relapse. Among those, 19 required an emergency visit. Sixteen patients had a 1-point disability progression on the Expanded Disability Status Scale (EDSS) score between two consecutive outpatient visits. Thirty-seven patients were found to have active lesions between first and second brain MRI. Medication adherence showed no impact on relapse occurrence or disability progression. Lower medication adherence (10% lower PDC) was associated with higher occurrence of active lesions (OR 1.25, P=0.038, 95% CI: 1.01-1.56). Higher disability prior to DMF initiation was related to a higher risk for relapse occurrence and EDSS progression. CONCLUSION: Our study showed high medication adherence among Slovenian persons with relapse-remitting MS on DMF treatment. Higher adherence was associated with lower incidence of the radiological progression of MS. Interventions for improving medication adherence should be intended for younger patients with higher disability prior treatment with DMF and those switching from alternative DMTs.

Plasma p-tau212: antemortem diagnostic performance and prediction of autopsy verification of Alzheimer's disease neuropathology.

Blood phosphorylated tau (p-tau) biomarkers, including p-tau217, show high associations with Alzheimer's disease (AD) neuropathologic change and clinical stage. Certain plasma p-tau217 assays recognize tau forms phosphorylated additionally at threonine-212, but the contribution of p-tau212 alone to AD is unknown. We developed a blood-based immunoassay that is specific to p-tau212 without cross-reactivity to p-tau217. Thereafter, we examined the diagnostic utility of plasma p-tau212. In five cohorts (n=388 participants), plasma p-tau212 showed high performances for AD diagnosis and for the detection of both amyloid and tau pathology, including at autopsy as well as in memory clinic populations. The diagnostic accuracy and fold changes of plasma p-tau212 were similar to those for p-tau217 but higher than p-tau181 and p-tau231. Immunofluorescent staining of brain tissue slices showed prominent p-tau212 reactivity in neurofibrillary tangles that co-localized with p-tau217 and p-tau202/205. These findings support plasma p-tau212 as a novel peripherally accessible biomarker of AD pathophysiology.

Diagnostic value of kappa free light chain index in patients with primary progressive multiple sclerosis - a multicentre study.

Background: Kappa free light chains (κ-FLC) in the cerebrospinal fluid (CSF) are an emerging biomarker in multiple sclerosis (MS). Objective: To investigate whether κ-FLC index has similar diagnostic value in patients with primary progressive multiple sclerosis (PPMS) compared to oligoclonal bands (OCB). Methods: Patients with PPMS were recruited through 11 MS centres across 7 countries. κ-FLC were measured by immunonephelometry/-turbidimetry. OCB were determined by isoelectric focusing and immunofixation. Results: A total of 174 patients (mean age of 52±11 years, 51% males) were included. κ-FLC index using a cut-off of 6.1 was positive in 161 (93%) and OCB in 153 (88%) patients. Conclusion: κ-FLC index shows similar diagnostic sensitivity than OCB in PPMS.

N-terminal and mid-region tau fragments as fluid biomarkers in neurological diseases.

Brain-derived tau secreted into CSF and blood consists of different N-terminal and mid-domain fragments, which may have a differential temporal course and thus, biomarker potential across the Alzheimer's disease continuum or in other neurological diseases. While current clinically validated total tau assays target mid-domain epitopes, comparison of these assays with new biomarkers targeting N-terminal epitopes using the same analytical platform may be important to increase the understanding of tau pathophysiology. We developed three total tau immunoassays targeting specific N-terminal (NTA and NTB total tau) or mid-region (MR total tau) epitopes, using single molecule array technology. After analytical validation, the diagnostic performance of these biomarkers was evaluated in CSF and compared with the Innotest total tau (and as proof of concept, with N-p-tau181 and N-p-tau217) in three clinical cohorts (n = 342 total). The cohorts included participants across the Alzheimer's disease continuum (n = 276), other dementias (n = 22), Creutzfeldt-Jakob disease (n = 24), acute neurological disorders (n = 18) and progressive supranuclear palsy (n = 22). Furthermore, we evaluated all three new total tau biomarkers in plasma (n = 44) and replicated promising findings with NTA total tau in another clinical cohort (n = 50). In CSF, all total tau biomarkers were increased in Alzheimer's disease compared with controls (P < 0.0001) and correlated with each other (rs = 0.53-0.95). NTA and NTB total tau, but not other total tau assays, distinguished amyloid-positive and amyloid-negative mild cognitive impairment with high accuracies (AUCs 84% and 82%, P < 0.001) matching N-p-tau217 (AUC 83%; DeLong test P = 0.93 and 0.88). All total tau assays were excellent in differentiating Alzheimer's disease from other dementias (P < 0.001, AUCs 89-100%). In Creutzfeldt-Jakob disease and acute neurological disorders, N-terminal total tau biomarkers had significantly higher fold changes versus controls in CSF (45-133-fold increase) than Innotest or MR total tau (11-42-fold increase, P < 0.0001 for all). In progressive supranuclear palsy, CSF concentrations of all total tau biomarkers were similar to those in controls. Plasma NTA total tau concentrations were increased in Alzheimer's disease compared with controls in two independent cohorts (P = 0.0056 and 0.0033), while Quanterix total tau performed poorly (P = 0.55 and 0.44). Taken together, N-terminal-directed CSF total tau biomarkers increase ahead of standard total tau alternatives in the Alzheimer's disease continuum, increase to higher degrees in Creutzfeldt-Jakob disease and acute neurological diseases and show better potential than Quanterix total tau as Alzheimer's disease blood biomarkers. For progressive supranuclear palsy, other tau biomarkers should continue to be investigated.

Effectiveness and safety of alemtuzumab in the treatment of active relapsing-remitting multiple sclerosis: a multicenter, observational study.

OBJECTIVE: So far, a limited number of real-world evidence studies about the effectiveness and safety of alemtuzumab (ALM) have been published, some of them with a relatively small number of included patients. We aimed to study the efficacy and safety of ALM in real-world clinical practice in two MS centers in Slovenia and Croatia. METHODS: This was a retrospective chart review of 71 consecutive patients with relapsing-remitting MS who were treated with ALM from 2015 till 2018. The following data were collected: gender, age at disease onset, disease duration at ALM initiation, previous disease modifying therapy, number of relapses, active MRI lesions, and EDSS in the year prior to ALM initiation and every year of follow-up. RESULTS: All patients completed the standard dosing schedule and were followed for a mean time of 3.2±1.1 years after the initiation of treatment. Complete data for the 2 years after treatment (relapses, EDSS, and MRI) were available for 48 patients, of which 14 (29.2%) achieved NEDA. Clinical NEDA was achieved in 38 out of 63 participants (60.3%). In year 1, 24 out of 57 (42.1%) patients achieved NEDA. In year 2, 26 out of 41 (63.4%) patients achieved NEDA. Lower EDSS prior to starting ALM was the only independent predictor of NEDA in a multivariable model. Adverse events occurred in 58 participants (84.1%), with no new safety signals identified. CONCLUSION: According to the data from our cohort of early active RRMS patients we conclude ALM efficacy remains high in the real-world clinical practice.

Approaches and challenges in the diagnosis and management of secondary progressive multiple sclerosis: A Central Eastern European perspective from healthcare professionals.

Secondary progressive multiple sclerosis (SPMS) is a debilitating condition characterized by gradual worsening after an initial relapsing disease course. Despite the recent advances in our understanding of the disease, the diagnosis and treatment of SPMS continue to be challenging in routine clinical practice. The aim of this review article is to present the views of leading MS experts on the challenges in the diagnosis and management of SPMS and clinicians' perspectives in Central and Eastern Europe. This article also provides recommendations of MS experts to improve the situation with diagnosis and management of SPMS. Many countries within Central and Eastern Europe have high prevalence of MS (>100 per 100,000 population). Consistent with the global trend, in the absence of reliable tests or biomarkers, SPMS at early stage remains undiagnosed. Due to diagnostic uncertainty and lack of a universally accepted disease definition, clinicians rely more on retrospective analysis of the clinical symptoms to confirm the diagnosis. With the lack of awareness and poor understanding of the timing of the onset of SPMS, clinicians may tend to direct attention to relapses than the symptoms of progression, which leads to underestimation of SPMS. Although several predictors of progression to SPMS have been identified, their predictive value is highly variable. Therefore, defining the transitioning period as a separate stage of MS is essential. According to experts' opinion, frequent follow-up of patients and periodic assessment of progression are recommended for the timely identification of patients transitioning from RRMS to SPMS. MSProDiscuss Tool is an example of a quick assessment tool for identifying patients progressing from RRMS to SPMS. MS progression is usually assessed by changes in Expanded Disability Status Scale (EDSS) scores. As EDSS scores tend to fluctuate when measured in the short term (3-6 months), a longer period (≥12 months) may be needed to confirm the progression. Assessment of cognitive function is also important for evaluating secondary progression. Compartmentalization of inflammation within the central nervous system is an important reason behind the limited success of disease-modifying therapies (DMTs) for treating SPMS. Most of the DMTs fail to cross the blood-brain barrier; only 38% of the tested DMTs achieved their primary endpoint in SPMS. In Europe, siponimod is the first oral treatment for adults with active SPMS. Particularly, in Central and Eastern Europe, patients with SPMS are still being prescribed less efficacious DMTs and interferons. The absence of alternative treatments in SPMS supports the use of new products (siponimod and others); however the decision to initiate siponimod therapy in more severe patients (EDSS score of 7 or higher) should be individualized in consultation with the payers. The focus should be on early treatment initiation to delay disease progression.

Head-to-head comparison of clinical performance of CSF phospho-tau T181 and T217 biomarkers for Alzheimer's disease diagnosis.

INTRODUCTION: Phosphorylated tau (p-tau) in cerebrospinal fluid (CSF) is an established Alzheimer's disease (AD) biomarker. Novel immunoassays targeting N-terminal and mid-region p-tau181 and p-tau217 fragments are available, but head-to-head comparison in clinical settings is lacking. METHODS: N-terminal-directed p-tau217 (N-p-tau217), N-terminal-directed p-tau181 (N-p-tau181), and standard mid-region p-tau181 (Mid-p-tau181) biomarkers in CSF were evaluated in three cohorts (n = 503) to assess diagnostic performance, concordance, and associations with amyloid beta (Aß). RESULTS: CSF N-p-tau217 and N-p-tau181 had better concordance (88.2%) than either with Mid-p-tau181 (79.7%-82.7%). N-p-tau217 and N-p-tau181 were significantly increased in early mild cognitive impairment (MCI)-AD (A+T-N-) without changes in Mid-p-tau181 until AD-dementia. N-p-tau217 and N-p-tau181 identified Aß pathophysiology (area under the curve [AUC] = 94.8%-97.1%) and distinguished MCI-AD from non-AD MCI (AUC = 82.6%-90.5%) signficantly better than Mid-p-tau181 (AUC = 91.2% and 70.6%, respectively). P-tau biomarkers equally differentiated AD from non-AD dementia (AUC = 99.1%-99.8%). DISCUSSION: N-p-tau217 and N-p-tau181 could improve diagnostic accuracy in prodromal-AD and clinical trial recruitment as both identify Aß pathophysiology and differentiate early MCI-AD better than Mid-p-tau181.

Intravenous immunoglobulins for the prevention of postpartum relapses in multiple sclerosis.

OBJECTIVES: To evaluate the effect of intravenous immunoglobulins (IVIG) on prevention of postpartum relapses in women with relapsing-remitting multiple sclerosis (RRMS). METHODS: This was a retrospective study performed in Ljubljana, Slovenia where the practice for all pregnant women with RRMS is to receive IVIG after the delivery (10 g monthly, during first 6 months after delivery) and in Zagreb, Croatia where no such practice exists. The following data were collected: date of delivery, maternal age at delivery, year of the RRMS diagnosis, EDSS, disease modifying therapy prior to pregnancy, relapses in the year prior, during and in the period of one year after pregnancy. RESULTS: Data on 132 pregnancies from 112 women (mean age at delivery 31.70±4.10, average disease duration 6.34±4.33) were analyzed. There was no association between the IVIG treatment and annualized relapse rate one year after the delivery (0.27 vs 0.38, rate ratio 1.409, 95% CI 0.764-2.598, p = 0.272). No risk factors for the postpartum relapse were identified (age at delivery, duration of RRMS, EDSS prior pregnancy, disease modifying therapy prior pregnancy, relapses in the year prior pregnancy, IVIG). CONCLUSION: This study provides no evidence of benefit for postpartum administration of IVIG in women with RRMS.

Visual but not verbal working memory interferes with balance in patients after optic neuritis suggestive of multiple sclerosis.

BACKGROUND: Subtle cognitive deficits are present in almost half of the patients with clinically isolated syndrome (CIS) suggestive of multiple sclerosis (MS). Similarly, subtle balance deficits can be detected at the earliest stages of the disease. To assess cognitive-motor interference (CMI) in nondisabled CIS patients, we studied postural performance using dual task paradigm in CIS patients presenting with optic neuritis. METHODS: We prospectively included 20 patients with visual acuity of 0.8 or more within the 3 months from unilateral ON. We also included 20 age, weight, height and education matched healthy subjects. Baseline cognitive performance of the patients was assessed using neuropsychological tests. Balance was studied by posturography (Po) and center of pressure (CoP) measures (maximal medio-lateral, maximal antero-posterior amplitudes, maximal CoP velocity and total CoP path. CMI between static balance and WM was investigated using a dual-task paradigm in three conditions: Po alone, Po+Brooks' visual working memory (WM) task and Po+2-back verbal WM task. RESULTS: The two most commonly affected cognitive domains in the patients were attention (52% of the patients) and executive functions (45% of the patients). Static balance as measured by higher maximal CoP velocity while standing alone (p = 0.02) was impaired in patients. Significantly lower maximal m-l CoP amplitude (p = 0.01) and total CoP path (p = 0.004) in the Po + Brooks' task condition compared to Po alone were observed in the group of ON patients but not in healthy subjects. The cost of dualtasking was highest in the ON patients under Po + Brooks' task (p = 0.04 for the total CoP path parameter). CONCLUSION: Static balance and cognition are impaired in the earliest MS. CMI between static balance and working memory is higher in the patients and while loading visual working memory. Dual-task paradigms should be used in rehabilitation programmes for patients at the very beginning of the disease.

Intrathecal immunoglobulin synthesis: The potential value of an adjunct test.

BACKGROUND: Detection of cerebrospinal fluid (CSF) specific oligoclonal bands (OCB) supports the diagnosis of multiple sclerosis (MS), but the method is technically demanding and gives only qualitative information. Kappa free light chains (KFLC) quantification could represent a convenient alternative. We evaluated the diagnostic accuracy of OCB and KFLC in our cohort to further estimate the gain in diagnostic performance when combining both of them. METHODS: KFLC were measured in paired serum and CSF samples of 80 patients with MS and 50 patients with non-inflammatory neurological disorders. OCB were detected using an in-house alkaline phosphatase assay. Likelihood ratio (LR) was used to explore the benefit of the combined KFLC and OCB test. RESULTS: Sensitivity of KFLC index (≥5.3) and intrathecal KFLC fraction (≥10%) was 96% and 95% respectively, compared to 91% sensitivity of OCB assay. Specificity was 96% for intrathecal KFLC synthesis and 98% for OCB. Probability of MS in the absence of OCB was further reduced with concurrently normal KFLC index. CONCLUSIONS: Normal KFLC parameters allow confident exclusion of intrathecal inflammation, but probability of MS is greater with positive OCB. Use of KFLC as an adjunct test might be beneficial in specialized MS centers with larger pretest probability.

Elevated CSF GAP-43 is Alzheimer's disease specific and associated with tau and amyloid pathology.

INTRODUCTION: The level of the presynaptic protein growth-associated protein 43 (GAP-43) in cerebrospinal fluid (CSF) has previously been shown to be increased in Alzheimer's disease (AD) and thus may serve as an outcome measure in clinical trials and facilitate earlier disease detection. METHODS: We developed an enzyme-linked immunosorbent assay for CSF GAP-43 and measured healthy controls (n = 43), patients with AD (n = 275), or patients with other neurodegenerative diseases (n = 344). In a subpopulation (n = 93), CSF GAP-43 concentrations from neuropathologically confirmed cases were related to Aß plaques, tau, α-synuclein, and TDP-43 pathologies. RESULTS: GAP-43 was significantly increased in AD compared to controls and most neurodegenerative diseases and correlated with the magnitude of neurofibrillary tangles and Aß plaques in the hippocampus, amygdala, and cortex. GAP-43 was not associated to α-synuclein or TDP-43 pathology. DISCUSSION: The presynaptic marker GAP-43 is associated with both diagnosis and neuropathology of AD and thus may be useful as a sensitive and specific biomarker for clinical research.

Recommendations for CSF AD biomarkers in the diagnostic evaluation of dementia.

This article presents recommendations, based on the Grading of Recommendations, Assessment, Development, and Evaluation method, for the clinical application of cerebrospinal fluid (CSF) amyloid-ß1-42, tau, and phosphorylated tau in the diagnostic evaluation of patients with dementia. The recommendations were developed by a multidisciplinary working group based on the available evidence and consensus from focused discussions for (i) identification of Alzheimer's disease (AD) as the cause of dementia, (ii) prediction of rate of decline, (iii) cost-effectiveness, and (iv) interpretation of results. The working group found sufficient evidence to support a recommendation to use CSF AD biomarkers as a supplement to clinical evaluation, particularly in uncertain and atypical cases, to identify or exclude AD as the cause of dementia. Because of insufficient evidence, it was uncertain whether CSF AD biomarkers outperform imaging biomarkers. Operational recommendations for the interpretation of ambiguous CSF biomarker results were also provided.

Recommendations for cerebrospinal fluid Alzheimer's disease biomarkers in the diagnostic evaluation of mild cognitive impairment.

This article presents recommendations, based on the Grading of Recommendations, Assessment, Development, and Evaluation method, for the clinical application of cerebrospinal fluid (CSF) amyloid-ß1-42, tau, and phosphorylated tau in the diagnostic evaluation of patients with mild cognitive impairment (MCI). The recommendations were developed by a multidisciplinary working group and based on the available evidence and consensus from focused group discussions for 1) prediction of clinical progression to Alzheimer's disease (AD) dementia, 2) cost-effectiveness, 3) interpretation of results, and 4) patient counseling. The working group recommended using CSF AD biomarkers in the diagnostic workup of MCI patients, after prebiomarker counseling, as an add-on to clinical evaluation to predict functional decline or conversion to AD dementia and to guide disease management. Because of insufficient evidence, it was uncertain whether CSF AD biomarkers outperform imaging biomarkers. Furthermore, the working group provided recommendations for interpretation of ambiguous CSF biomarker results and for pre- and post-biomarker counseling.

Comparison of Different Matrices as Potential Quality Control Samples for Neurochemical Dementia Diagnostics.

BACKGROUND: Assay-vendor independent quality control (QC) samples for neurochemical dementia diagnostics (NDD) biomarkers are so far commercially unavailable. This requires that NDD laboratories prepare their own QC samples, for example by pooling leftover cerebrospinal fluid (CSF) samples. OBJECTIVE: To prepare and test alternative matrices for QC samples that could facilitate intra- and inter-laboratory QC of the NDD biomarkers. METHODS: Three matrices were validated in this study: (A) human pooled CSF, (B) Aß peptides spiked into human prediluted plasma, and (C) Aß peptides spiked into solution of bovine serum albumin in phosphate-buffered saline. All matrices were tested also after supplementation with an antibacterial agent (sodium azide). We analyzed short- and long-term stability of the biomarkers with ELISA and chemiluminescence (Fujirebio Europe, MSD, IBL International), and performed an inter-laboratory variability study. RESULTS: NDD biomarkers turned out to be stable in almost all samples stored at the tested conditions for up to 14 days as well as in samples stored deep-frozen (at - 80°C) for up to one year. Sodium azide did not influence biomarker stability. Inter-center variability of the samples sent at room temperature (pooled CSF, freeze-dried CSF, and four artificial matrices) was comparable to the results obtained on deep-frozen samples in other large-scale projects. CONCLUSION: Our results suggest that it is possible to replace self-made, CSF-based QC samples with large-scale volumes of QC materials prepared with artificial peptides and matrices. This would greatly facilitate intra- and inter-laboratory QC schedules for NDD measurements.

The Central Biobank and Virtual Biobank of BIOMARKAPD: A Resource for Studies on Neurodegenerative Diseases.

Biobanks are important resources for biomarker discovery and assay development. Biomarkers for Alzheimer's and Parkinson's disease (BIOMARKAPD) is a European multicenter study, funded by the EU Joint Programme-Neurodegenerative Disease Research, which aims to improve the clinical use of body fluid markers for the diagnosis and prognosis of Alzheimer's disease (AD) and Parkinson's disease (PD). The objective was to standardize the assessment of existing assays and to validate novel fluid biomarkers for AD and PD. To support the validation of novel biomarkers and assays, a central and a virtual biobank for body fluids and associated data from subjects with neurodegenerative diseases have been established. In the central biobank, cerebrospinal fluid (CSF) and blood samples were collected according to the BIOMARKAPD standardized pre-analytical procedures and stored at Integrated BioBank of Luxembourg. The virtual biobank provides an overview of available CSF, plasma, serum, and DNA samples at each site. Currently, at the central biobank of BIOMARKAPD samples are available from over 400 subjects with normal cognition, mild cognitive impairment (MCI), AD, frontotemporal dementia (FTD), vascular dementia, multiple system atrophy, progressive supranuclear palsy, PD, PD with dementia, and dementia with Lewy bodies. The virtual biobank contains information on over 8,600 subjects with varying diagnoses from 21 local biobanks. A website has been launched to enable sample requests from the central biobank and virtual biobank.

Validation of a quantitative cerebrospinal fluid alpha-synuclein assay in a European-wide interlaboratory study.

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.

Interferons beta have vasoconstrictive and procoagulant effects: a woman who developed livedo reticularis and Raynaud phenomenon in association with interferon beta treatment for multiple sclerosis.

A 31-year-old woman with MS developed livedo reticularis and secondary Raynaud phenomenon 2.5 years after introduction of interferon beta-1b. The symptoms disappeared after withdrawal of the drug. Livedo reticularis and Raynaud phenomenon as well as pulmonary arterial hypertension, venous sinus thrombosis, pulmonary embolism and renal thrombotic microangiopathy have all been described in association with interferon beta therapy. These complications strongly suggest that type I interferons have vasoconstrictive and procoagulant effects with potentially serious systemic complications.