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Objectives Clinical laboratory results are required for critical medical decisions, underscoring the importance of quality results. As part of total quality management, external quality assessment (EQA) is a vital component to ensure laboratory accuracy. The goal of this survey was to evaluate the current status of global laboratory quality systems and assess the need for implementation, expansion, or harmonization of EQA programs (EQAP) for Clinical Chemistry and Laboratory Medicine. Methods The International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) Task Force on Global Laboratory Quality (TF-GLQ) conducted a survey of IFCC full and affiliate members (n=110) on laboratory quality practice. A total of 41 (37.3%) countries representing all IFCC regions except North America provided responses about EQA availability and practices. Results All 41 countries perform EQA, 38 reported that their laboratories had EQA policies and procedures, and 39 further act/evaluate unacceptable EQA results. 39 countries indicated they have international and/or national EQAP and 30 use alternative performance assessments. EQA frequency varied among countries. Generally, an EQAP provided the EQA materials (40/41) with four countries indicating that they did not have an EQAP in their country. Conclusions Globally, most laboratories participate in an EQAP and have defined quality procedures for EQA. There remain gaps in EQA material availability and implementation of EQA as a part of a total laboratory quality system. This survey highlights the need for education, training, and harmonization and will guide efforts of the IFCC TF-GLQ in identifying areas for enhancing global laboratory quality practices.

Resume La maladie d’Alzheimer est la plus frequente des maladies neurodegeneratives. On estime qu’environ 1 million de personnes sont atteintes de cette pathologie en France. Son evolution est progressive, des premiers stades ou l’atteinte cognitive et comportementale est legere aux stades moderes puis tardifs correspondant a une perte totale d’autonomie. Elle est caracterisee sur le plan physiopathologique par un dysfonctionnement synaptique, une perte neuronale et des agregats de proteines mal conformees : on parle alors de « proteino-pathie ». Son diagnostic est multifactoriel et repose sur un faisceau d’arguments cliniques, radiologiques, neuropsychologiques et biologiques. Ces marqueurs sont les peptides amyloides Aβ 1-40 et Aβ 1-42 et les proteines TAU totale et hyperphosphorylees, en general en position 181. Ils sont mesures dans le liquide cerebrospinal et refletent la presence des lesions cerebrales, tres precocement dans l’evolution de la maladie. La phase pre-analytique est delicate, necessitant l’utilisation d’un tube specifique. Malgre le developpement de methodes automatisees, ces dosages manquent de standardisation : les seuils sont donc dependants des techniques et des laboratoires. Il n’est pas recommande de realiser le dosage de ces marqueurs de facon systematique mais de les reserver aux formes les moins typiques ou touchant les adultes jeunes. Le dialogue clinico- biologique est alors fondamental pour la bonne interpretation des resultats.

Resume Les maladies a prions sont des maladies neurodegeneratives rares d’issue toujours fatale. Elles sont caracterisees par l’accumulation principalement cerebrale d’une isoforme pathologique (PrPsc) d’une proteine cellulaire normale, la PrPc. Du fait de leur caractere transmissible d’homme a homme et animal-homme, ces maladies sont etroitement surveillees par les autorites de sante et a declaration obligatoire des leur suspicion. Leur diagnostic est donc un enjeu majeur de sante publique alors meme que le diagnostic de certitude reste l’examen neuropathologique, tres majoritairement realise en post-mortem. Les marqueurs biologiques jouent un role important dans la demarche diagnostique du vivant du patient et dans la surveillance de ces maladies. En effet, la detection de la proteine 1433 dans le liquide cerebrospinal (LCS), marqueur non etiologique, permet d’augmenter la probabilite diagnostique. De nombreux efforts ont ete menes pour mesurer directement la PrPsc dans les fluides biologiques. Seuls des progres technologiques recents reposant sur des methodes innovantes d’amplification des proteines ont permis de la mesurer dans le LCS. Cependant, ces technologies necessitent une mise en œuvre dans des environnements de securite microbiologique de niveau 3. Ces techniques d’avenir, reservees a des centres de reference experts, sont de realisation delicate, manquent de robustesse et de standardisation avant de pouvoir etre proposees comme outils diagnostiques en pratique courante.

Robust intraocular markers are needed in clinical practice for several inflammatory ophthalmological conditions in addition to advanced imaging, histology and immunohistochemistry tests in order to assure reliable diagnosis. Neopterin (NPt) is produced by activated lymphocyte T cells and is known to increase within the CNS in proinflammatory or early infectious states. This study aimed to measure intraocular NPt in aqueous liquid following intraocular liquid biopsy using standard methods. We enrolled 20 healthy patients without known inflammatory history or medication underdoing cataract surgery and analyzed samples for 19 out of 20. NPt level was measured below 1,9 nmol/l in 16 patients (84 %) and less than 3 nmol/l in 94,74%. Given the first time that NPt is measured in intraocular liquids we compared with the established reference limits within the CSF. These findings suggest that NPt could serve as a potential additional signature in ophthalmological conditions to differentiate between any or proinflammatory intraocular state, as well in follow-up.

Prions are neurotropic pathogens composed of misfolded assemblies of the host-encoded prion protein PrPC which replicate by recruitment and conversion of further PrPC by an autocatalytic seeding polymerization process. While it has long been shown that mouse-adapted prions cannot replicate and are rapidly cleared in transgenic PrP0/0 mice invalidated for PrPC, these experiments have not been done with other prions, including from natural resources, and more sensitive methods to detect prion biological activity. Using transgenic mice expressing human PrP to bioassay prion infectivity and RT-QuIC cell-free assay to measure prion seeding activity, we report that prions responsible for the most prevalent form of sporadic Creutzfeldt–Jakob disease in human (MM1-sCJD) can persist indefinitely in the brain of intra-cerebrally inoculated PrP0/0 mice. While low levels of seeding activity were measured by RT-QuIC in the brain of the challenged PrP0/0 mice, the bio-indicator humanized mice succumbed at a high attack rate, suggesting relatively high levels of persistent infectivity. Remarkably, these humanized mice succumbed with delayed kinetics as compared to MM1-sCJD prions directly inoculated at low doses, including the limiting one. Yet, the disease that did occur in the humanized mice on primary and subsequent back-passage from PrP0/0 mice shared the neuropathological and molecular characteristics of MM1-sCJD prions, suggesting no apparent strain evolution during lifelong dormancy in PrP0/0 brain. Thus, MM1-sCJD prions can persist for the entire life in PrP0/0 brain with potential disease potentiation on retrotransmission to susceptible hosts. These findings highlight the capacity of prions to persist and rejuvenate in non-replicative environments, interrogate on the type of prion assemblies at work and alert on the risk of indefinite prion persistence with PrP-lowering therapeutic strategies., Abbreviated summary Martin et al. report lifelong persistence of sporadic Creutzfeldt–Jakob disease prions in the brain of mice lacking the endogenous prion protein gene and disease potentiation—without strain evolution—on retrotransmission to humanized mice. These findings highlight the risk of indefinite prion persistence with therapeutic strategies lowering the prion protein., Graphical Abstract Graphical Abstract

Early or primary injury due to brain aggression, such as mechanical trauma, hemorrhage or is-chemia, triggers the release of damage-associated molecular patterns (DAMPs) in the extracellular space. Some DAMPs, such as S100B, participate in the regulation of cell growth and survival but may also trigger cellular damage as their concentration increases in the extracellular space. When DAMPs bind to pattern-recognition receptors, such as the receptor of advanced glycation end-products (RAGE), they lead to non-infectious inflammation that will contribute to necrotic cell clearance but may also worsen brain injury. In this narrative review, we describe the role and ki-netics of DAMPs and RAGE at the acute phase of brain injury. We searched the MEDLINE database for “DAMPs” or “RAGE” or “S100B” and “traumatic brain injury” or “subarachnoid hemorrhage” or “stroke”. We selected original articles reporting data on acute brain injury pathophysiology, from which we describe DAMPs release and clearance upon acute brain injury, and the implication of RAGE in the development of brain injury. We will also discuss the clinical strategies that emerge from this overview in terms of biomarkers and therapeutic perspectives

Background Several studies have investigated the value of alpha-synuclein assay in the cerebrospinal fluid (CSF) of Alzheimer’s disease (AD) and dementia with Lewy bodies (DLB) patients in the differential diagnosis of these two pathologies. However, very few studies have focused on this assay in AD and DLB patients at the MCI stage. Methods All patients were enrolled under a hospital clinical research protocol from the tertiary Memory Clinic (CM2R) of Alsace, France, by an experienced team of clinicians. A total of 166 patients were included in this study: 21 control subjects (CS), 51 patients with DLB at the prodromal stage (pro-DLB), 16 patients with DLB at the demented stage (DLB-d), 33 AD patients at the prodromal stage (pro-AD), 32 AD patients at the demented stage (AD-d), and 13 patients with mixed pathology (AD+DLB). CSF levels of total alpha-synuclein were assessed using a commercial enzyme-linked immunosorbent assay (ELISA) for alpha-synuclein (AJ Roboscreen). Alzheimer’s biomarkers (t-Tau, P-Tau, Aβ42, and Aβ40) were also measured. Results The alpha-synuclein assays showed a significant difference between the AD and DLB groups. Total alpha-synuclein levels were significantly higher in AD patients than in DLB patients. However, the ROC curves show a moderate discriminating power between AD and DLB (AUC = 0.78) which does not improve the discriminating power of the combination of Alzheimer biomarkers (AUC = 0.95 with or without alpha-synuclein). Interestingly, the levels appeared to be altered from the prodromal stage in both AD and DLB. Conclusions The modification of total alpha-synuclein levels in the CSF of patients occurs early, from the prodromal stage. The adding of alpha-synuclein total to the combination of Alzheimer’s biomarker does not improve the differential diagnosis between AD and DLB. Trial registration ClinicalTrials.gov, NCT01876459 (AlphaLewyMa)

Background: Several studies have investigated the value of alpha-synuclein assay in the cerebrospinal fluid (CSF) of Alzheimer’s disease (AD) and dementia with Lewy bodies (DLB) patients in the differential diagnosis of these two pathologies. However, very few studies have focused on this assay in AD and DLB patients at the MCI stage.Methods: All patients were enrolled under a hospital clinical research protocol from the tertiary Memory Clinic (CM2R) of Alsace, France, by an experienced team of clinicians. A total of 166 patients were included in this study: 21 control subjects (CS), 51 patients with DLB at the prodromal stage (pro-DLB), 16 patients with DLB at the demented stage (DLB-d), 33 AD patients at the prodromal stage (pro-AD), 32 AD patients at the demented stage (AD-d) and 13 patients with mixed pathology (AD+DLB). CSF levels of total alpha-synuclein were assessed using a commercial enzyme-linked immunosorbent assay (ELISA) for alpha-synuclein (AJ Roboscreen). Alzheimer’s biomarkers (t-Tau, P-Tau, Aβ42 and Aβ40) were also measured.Results: The alpha-synuclein assays showed a significant difference between the AD and DLB groups. Total alpha-synuclein levels were significantly higher in AD patients than in DLB patients. Interestingly, the levels appeared to be altered from the prodromal stage in both AD and DLB. Furthermore, alpha-synuclein levels were elevated not only in AD patients with a typical “Alzheimer” profile (i.e. 2 or 3 pathological biomarkers) but also in AD patients with an atypical “Alzheimer” profile (i.e. one or no pathological biomarkers).Conclusions: The modification of total alpha-synuclein levels in the CSF of patients occurs early, from the prodromal stage. Moreover, alpha-synuclein assay appears to be of particular interest in the differential diagnosis of AD in cases where the Alzheimer biomarkers do not have a typical profile of the disease, i.e. when there is only one or no pathological biomarkers.Trial registration: ClinicalTrials.gov, (AlphaLewyMa, Identifier: NCT01876459)

Background: Several studies have investigated the value of alpha-synuclein assay in the cerebrospinal fluid (CSF) of Alzheimer’s disease (AD) and Dementia with Lewy Bodies (DLB) patients in the differential diagnosis of these two pathologies. However, very few studies have focused on this assay in AD and DLB patients at the MCI stage. Methods: All patients were enrolled under a hospital clinical research protocol from the tertiary Memory Clinic (CM2R) of Alsace by an experienced team of clinicians. A total of 166 patients were included in this study: 21 control subjects (CS), 51 patients with DLB at the prodromal stage (pro-DLB), 16 patients with DLB at the demented stage (DLB-d), 33 AD patients at the prodromal stage (pro-AD) and 32 AD patients at the demented stage (AD-d). CSF levels of total alpha-synuclein were assessed using commercial enzyme-linked immunosorbent assay (ELISA) for alpha-synuclein (AJ Roboscreen). Alzheimer's biomarkers (t-Tau, P-Tau, Aβ42 and Aβ40) were also measured.Results: The alpha-synuclein assays showed a significant difference between the AD and DLB groups. Total alpha-synuclein levels are significantly higher in AD patients than in DLB patients. Interestingly is that the levels seem to be altered from the prodromal stage in both AD and DLB. Furthermore, by dividing the patients according to the profiles of Alzheimer's biomarkers typically found or not for each of the two pathologies and then classifying the patients according to the level of alpha-synuclein, we find that alpha-synuclein levels are elevated not only for AD patients with typical “Alzheimer” profile (i.e. 2 or 3 pathological biomarkers) but also for AD patients with a non-typical “Alzheimer” profile (i.e. none or one pathological biomarker).Conclusions: The modification of total alpha-synuclein levels in the CSF of patients occurs early from the prodromal stage. Moreover, alpha-synuclein assay appears to be of particular interest in the differential diagnosis of AD in cases where the Alzheimer biomarkers do not have a typical profile of the disease, i.e. when there is only one or no pathological biomarker.Trial registration: ClinicalTrials.gov, (AlphaLewyMa, Identifier: NCT01876459)

Background and purpose Neuropsychiatric symptoms are commonly observed in neurodegenerative diseases. No biomarker is currently available to diagnose psychiatric conditions. As a consequence, the distinction between psychiatric and neurodegenerative disorders can be challenging in daily practice. Methods This retrospective study included a cohort of 64 primary psychiatric patients (PSY) and 162 patients suffering from various neurodegenerative disorders (NDG). Total tau (t-Tau), phosphorylated tau (p-Tau), Aβ1-42 peptide (Aβ1-42) and neurofilament light chain protein (NfL) were analysed in cerebrospinal fluid. The discrimination between PSY and NDG patients was assessed using both individual and combined analysis of cerebrospinal fluid markers. Results Cerebrospinal fluid t-Tau and NfL exhibited the best diagnostic performances: they were able to discriminate between PSY and each subgroup of NDG patients. t-Tau had the highest sensitivity (93.8%) but a poor specificity (67.3%). Indeed, some NDG subgroups exhibited low t-Tau levels comparable to PSY patients. A sequential combination t-Tau + NfL improved the characterization of patients, especially in these particular subgroups, increasing specificity up to 89.6% without modification of sensitivity. Finally, this combination of markers led to a high classification rate of 90.7% for the whole cohort of patients. Conclusion The sequential combination t-Tau + NfL enables the biological detection of neurodegeneration in patients with psychiatric features. This association of markers seems to be a promising strategy for a differential diagnosis in clinical practice between primary psychiatric conditions and neurodegenerative disorders, thus improving medical care of patients.

Background/Aims: The aim of the study was to assess the theory of haploinsufficiency in C9ORF72 expansion carriers, the most frequent causative gene of frontotemporal dementia. Methods: Plasmatic concentrations of C9orf72 protein were measured in 33 patients suspected of familial frontotemporal dementia using an enzyme-linked immunosorbent assay. Results: No difference was observed between C9ORF72 expansion carriers (21.2% of patients) and noncarriers (78.8% of patients). C9orf72 protein determination is not a suitable biomarker for screening C9ORF72 expansion carriers. Conclusion: Our results provide new evidence against the hypothesis of haploinsufficiency leading to frontotemporal dementia in C9ORF72 expansion carriers.

Exposure of human populations to bovine spongiform encephalopathy through contaminated food has resulted in, It is hypothesised that exposure to bovine spongiform encephalopathy through contaminated food could have resulted in a large proportion of latent variant Creutzfeldt-Jakob disease cases in humans. Here the authors demonstrate that inoculation with blood from non-symptomatic, vCJD infected humans, results in a unique prion-like disorder in mice and macaques.

Sporadic Creutzfeldt-Jakob disease (sCJD) is a fatal rapidly progressive dementia. The detection of 14-3-3 protein in cerebrospinal fluid (CSF) is included in the WHO diagnostic criteria for the pre-mortem diagnosis of CJD. The aim of this study is to assess CSF 14-3-3 protein analytical and diagnostic performances using a new automated capillary Western technology (Simple Western technology-SW). For the validation of this assay, samples from a cohort of 268 patients suspected from sCJD were analyzed: 77 sCJD (including 40 definite sCJD) and 191 non-CJD samples were tested using both SW and the current Western Blot (WB) assays. Automated capillary Western determination provided better analytical performances than WB with a lower intra- and inter-assay variability. Analytical interferences such as hemolysis and high total protein concentration known to lead to false positive WB results were also assessed using SW assay: unfortunately, these interferences still remain confounders of CSF 14-3-3 protein determination. Finally, automated capillary Western assay's sensitivity and specificity were superior to those of WB assay (93.5 and 95.3%, respectively, compared to 92.2 and 84.8% for WB). In conclusion, with a shorter time of analysis than WB assays' (4 h versus 1.5 day), automated capillary Western assay is an excellent routine alternative method to the currently performed WB assay for CSF 14-3-3 protein detection in patients suspected of sporadic Creutzfeldt-Jakob disease.

Creutzfeldt-Jakob disease (CJD) is a human prion disease with different etiologies. To determine the spectrum of tau pathologies in CJD, we assessed phospho-Tau (pTau) immunoreactivities in 75 sporadic CJD cases including an evaluation of the entorhinal cortex and six hippocampal subregions. Twelve cases (16%) showed only small tau-immunoreactive neuritic profiles. Fifty-two (69.3%) showed additional tau pathology in the medial temporal lobe compatible with primary age related tauopathy (PART). In 22/52 cases the lower pTau immunoreactivity load in the entorhinal cortex as compared to subiculum, dentate gyrus or CA4 region of the hippocampus was significantly different from the typical distribution of the Braak staging. A further 11 cases (14.7%) showed widespread tau pathologies compatible with features of primary tauopathies or the gray matter type of ageing-related tau astrogliopathy (ARTAG). Prominent gray matter ARTAG was also observed in two out of three additionally examined V203I genetic CJD cases. Analysis of cerebrospinal fluid revealed prominent increase of total tau protein in cases with widespread tau pathology, while pTau (T181) level was increased only in four. This correlated with immunohistochemical observations showing less pathology with anti-pTau T181 antibody when compared to anti-pTau S202/T205, T212/S214 and T231. The frequency of tau pathologies is not unusually high in sporadic CJD and does not precisely relate to PrP deposition. However, the pattern of hippocampal tau pathology often deviates from the stages of Braak. Currently applied examination of cerebrospinal fluid pTau (T181) level does not reliably reflect primary tauopathies, PART and ARTAG seen in CJD brains.

International audience

The French Minister of Health published a decree on May 29th of 2018 removing the drugs used to fight against symptoms due to Alzheimer's disease (donepezil, rivastigmine, galantamine, memantine) from the list of available reimbursed drugs. This follows the advice delivered by the High Authority for Health in 2016 and 2018 stating an "insufficient medical benefit and dangerousness because of significant side effects". The main French scientific and medical societies and professional associations want to state here their deep disagreement regarding this unfair decision. The evidence-based medicine related to these drugs reaches a high level in literature, whereas the clinical relevance of these treatments must be considered with co-prescription of psychosocial interventions and related approaches. As no serious pharmacovigilance signal has been provided by health authorities, the ratio of benefits/risks favors these drugs.

Cerebral microdialysis could be useful to detect delayed cerebral ischemia in aneurysmal subarachnoid haemorrhage patients. The optimal location of the probes, however, remains controversial. Here, we determined the vascular territories with the highest infarct risk in relation to aneurysm location to define probe implantation guidelines. These guidelines were retrospectively validated by studying the likelihood of probe to fall in a secondary infarct area, and by analysing their influence to predict patient outcome. The vascular territories with highest risk of infarction were the anterior cerebral arteries for anterior communicating artery aneurysms and the ipsilateral middle cerebral artery for internal carotid artery, posterior communicating artery and middle cerebral artery aneurysms. When cerebral microdialysis probes had been implanted in these territories, 79% were located within an infarcted area versus 54% when they were implanted in other territories. Delayed cerebral ischemia was detected only when the probe was located within a brain area later affected by secondary infarction, which could justify the use of implantation guidelines. Moreover, individual patient outcomes could be predicted when probes were placed in the brain territories as suggested by this study. Thus, a precise probe placement algorithm can improve delayed cerebral ischemia detection sensitivity and allow for a better prediction concerning patient outcome.

The functional outcome of patients with subarachnoid hemorrhage is difficult to predict at the individual level. The monitoring of brain energy metabolism has proven to be useful in improving the pathophysiological understanding of subarachnoid hemorrhage. Nonetheless, brain energy monitoring has not yet clearly been included in official guidelines for the management of subarachnoid hemorrhage patients, likely because previous studies compared only biological data between two groups of patients (unfavorable vs favorable outcomes) and did not determine decision thresholds that could be useful in clinical practice. Therefore, this Viewpoint discusses recent findings suggesting that monitoring biomarkers of brain energy metabolism at the level of individuals can be used to predict the outcomes of subarachnoid hemorrhage patients. Indeed, by taking into account specific neurochemical patterns obtained by local or global monitoring of brain energy metabolism, it may become possible to predict routinely, and with sufficient sensitivity and specificity, the individual outcomes of subarachnoid hemorrhage patients. Moreover, combining both local and global monitoring improves the overall performance of individual outcome prediction. Such a combined neurochemical monitoring approach may become, after prospective clinical validation, an important component in the management of subarachnoid hemorrhage patients to adapt individualized therapeutic interventions.

Alzheimer disease (AD) is a devastating neurodegenerative disorder characterized by a progressive decline in cognitive function. In 2010, an estimated 36 million people worldwide had AD or a related dementia, with this number projected to double by 2030. The social and economic burden of AD is well documented and will be amplified by this increase in prevalence. The initial pathophysiologic changes of AD are found in the hippocampus region of the brain, disrupting memory and the ability to learn. AD progression is linked to nerve cell dysfunction and cell death due to the accumulation of 2 protein aggregates: β-amyloid (Aβ)5 and tau. In the cerebrospinal fluid (CSF), these proteins are biomarkers for AD. Cleavage of the amyloid precursor protein (APP) generates varying lengths of Aβ peptides (38–43 amino acids) that accumulate in the extracellular space. Of these monomers, Aβ-42 is the major form associated with AD. In addition, tau entanglement is also associated with AD and consists of insoluble hyperphosphorylated tau protein in the intracellular space. Both total tau (t-tau) and phosphorylated tau (p-tau) proteins are measured and associated with AD. Currently, clinical trials are testing therapies that target these proteins in hopes to delay or halt the cognitive decline in AD patients. In this Q&A, we discuss the current state and future direction of biomarkers, assays, and therapies for AD with 3 experts. Established Alzheimer biomarkers include β-amyloid and tau protein in CSF, as well as imaging techniques that involve MRI and positron emission tomography (PET). What are the limitations of these biomarkers that restrict them mostly to research purposes? Erik Portelius: In the recently updated diagnostic criteria for AD (the International Working Group-2 criteria), the CSF AD biomarkers (Aβ-42, t-tau, and p-tau) and neuroimaging with Pittsburgh compound B (PiB)-PET were included. Although MRI may mirror the disease …

Altres ajuts: C. E. Teunissen PhD received grants from the European Commission, the Dutch Research Council (ZonMW), Association of Frontotemporal Dementia/Alzheimer's Drug Discovery Foundation, Alzheimer Netherlands. M. Otto MD PhD received funding from the EU, German ministry of science and technology (KNDD/FTLD) the Baden-Wuertemberg Foundation. Sebastiaan Engelborghs MD, PhD received funding from the EU/EFPIA Innovative Medicines Initiative Joint Undertaking (EMIF grant number 115372); the University Research Fund of the University of Antwerp; the Flemish Impulse Financing of Networks for Dementia Research (VIND); and Flanders Innovation & Entrepreneurship (VLAIO). Sanna-Kaisa Herukka MD, PhD received funding from Finnish Medical Foundation and Finnish Medical Society Duodecim. Sylvain Lehmann MD, PhD has received support from "France Alzheimer", the National French Alzheimer effort ("Plan Alzheimer"). Piotr Lewczuk MD, PhD has received support from the Innovative Medicines Initiative Joint Undertaking under EMIF grant agreement number 115372, resources of which are composed of financia contributions from the European Union's Seventh Framework Programme (FP7/2007-2013) and EFPIA companies' in kind contribution. Hayrettin Tumani MD received research support from Hertie-Stiftung, BMBF, University of Ulm and Landesstiftung BW. Martin R. Turner MBBS, PhD is supported by the Medical Research Council & Motor Neurone Disease Association Lady Edith Wolfson Senior Clinical Fellowship (MR/K01014X/1). MM Verbeek PhD received grants from Alzheimer Nederland (number 14502) and the CAVIA project, which has been made possible by ZonMW (number 733050202). The CAVIA project is part of 'Memorabel', the research and innovation programme for dementia, as part of the Dutch national 'Deltaplan for Dementia': zonmw.nl/dementiaresearch. The CAVIA project is a consortium of Radboudumc, LUMC, Erasmus MC, VUmc, ADX Neurosciences, Philips Healthcare, Stony Brook University and Massachusetts General Hospital. Jens Wiltfang is supported by an Ilídio Pinho professorship and iBiMED (UID/BIM/04501/2013), at the University of Aveiro, Portugal. Lucilla Parnetti MD, PhD, received grants from EU-FP 6 and 7 (cNeupro, PharmaCog), MJFF, Italian Ministry of University and Research and Italian Ministry of Health. K Blennow MD, PhD holds the Torsten Söderberg Professorship in Medicine at the Royal Swedish Academy of Sciences. Body fluid biomarkers have great potential for different clinical purposes, including diagnosis, prognosis, patient stratification and treatment effect monitoring. This is exemplified by current use of several excellent biomarkers, such as the Alzheimer's disease cerebrospinal fluid (CSF) biomarkers, anti-neuromyelitis optica antibodies and blood neurofilament light. We still, however, have a strong need for additional biomarkers and several gaps in their development and implementation should be filled. Examples of such gaps are i) limited knowledge of the causes of neurological diseases, and thus hypotheses about the best biomarkers to detect subclinical stages of these diseases; ii) the limited success translating discoveries obtained by e.g. initial mass spectrometry proteomic low-throughput studies into immunoassays for widespread clinical implementation; iii) lack of interaction among all stakeholders to optimise and adapt study designs throughout the biomarker development process to medical needs, which may change during the long period needed for biomarker development. The Society for CSF Analysis and Clinical Neurochemistry (established in 2015) has been founded as a concerted follow-up of large standardisation projects, including BIOMARKAPD and SOPHIA, and the BioMS-consortium. The main aims of the CSF society are to exchange high level international scientific experience, to facilitate the incorporation of CSF diagnostics into clinical practice and to give advice on inclusion of CSF analysis into clinical guidelines. The society has a broad scope, as its vision is that the gaps in development and implementation of biomarkers are shared among almost all neurological diseases and thus they can benefit from the activities of the society.

The accumulation of aggregated alpha-synuclein (α-syn) in multiple brain regions is a neuropathological hallmark of synucleinopathies. Multiple system atrophy (MSA) is a synucleinopathy characterized by the predominant cerebral accumulation of aggregated α-syn as cytoplasmic glial inclusions (CGI). A premortem diagnosis tool would improve early diagnosis and help monitoring disease progression and therapeutic efficacy. One Positron Emission Tomography (PET) study suggested [11C]BF-227 as a promising radiotracer for monitoring intracellular α-syn deposition in MSA patients. We sought to confirm the binding of this radiotracer to α-syn using state-of-the-art autoradiography. Medulla sections were obtained from 9 MSA patients and 9 controls (London Neurodegenerative Diseases Brain Bank). [18F]BF-227, chemically identical to [11C]BF-227, was used at nanomolar concentrations to perform in vitro autoradiography assays. Autoradiograms were superimposed on fluorescent staining from the conformational anti-α-syn antibody 5G4 and quantified after immunofluorescence-driven definition of regions of interest. Autoradiography showed no specific signals in MSA patients in comparison to controls despite widespread pathology detected by immunofluorescence. Autoradiography does not support a significant binding of [18F]BF-227 to CGI at concentrations typically achieved in PET experiments.

BACKGROUND The diagnosis of primary central nervous system lymphoma (PCNSL) can be challenging. PCNSL lesions are frequently located deep within the brain, and performing a cerebral biopsy is not always feasible. The aim of this study was to investigate the diagnostic value of CSF neopterin, a marker of neuroinflammation, in immunocompetent patients with suspected PCNSL. METHODS We retrospectively reviewed the characteristics of 124 patients with brain tumor (n = 82) or an inflammatory CNS disorder (n = 42) in whom CSF neopterin levels were assessed. Twenty-eight patients had PCNSL, 54 patients had another type of brain tumor (glioma n = 36, metastasis n = 13, other n = 5), and 13 patients had a pseudotumoral inflammatory brain lesion. RESULTS CSF neopterin levels were significantly higher in the patients with PCNSL than in those with other brain tumors (41.8 vs 5.1 nmol/L, P < .001), those with pseudotumoral inflammatory brain lesions (41.8 vs 4.3 nmol/L, P < .001), and those with nontumefactive inflammatory CNS disorders (41.8 vs 3.8 nmol/L, P < .001). In the 95 patients with space-occupying brain lesions, at a cutoff of 10 nmol/L, the sensitivity of this approach was 96% and the specificity was 93% for the diagnosis of PCNSL. The positive and negative predictive values were 84% and 98%, respectively. CONCLUSION Assessing CSF neopterin levels in patients with a suspected brain tumor might be helpful for the positive and differential diagnosis of PCNSL. A prospective study is warranted to confirm these results.

Prions are proteinaceous pathogens responsible for subacute spongiform encephalopathies in animals and humans. The prions responsible for bovine spongiform encephalopathy (BSE) are zoonotic agents, causing variant Creutzfeldt-Jakob disease (CJD) in humans. The transfer of prions between species is limited by a species barrier, which is thought to reflect structural incompatibilities between the host cellular prion protein (PrPC) and the infecting pathological PrP assemblies (PrPSc) constituting the prion. A BSE strain variant, designated L-BSE and responsible for atypical, supposedly spontaneous forms of prion diseases in aged cattle, demonstrates zoonotic potential, as evidenced by its capacity to propagate more easily than classical BSE in transgenic mice expressing human PrPCand in nonhuman primates. In humanized mice, L-BSE propagates without any apparent species barrier and shares similar biochemical PrPScsignatures with the CJD subtype designated MM2-cortical, thus opening the possibility that certain CJD cases classified as sporadic may actually originate from L-type BSE cross-transmission. To address this issue, we compared the biological properties of L-BSE and those of a panel of CJD subtypes representative of the human prion strain diversity using standard strain-typing criteria in human PrP transgenic mice. We found no evidence that L-BSE causes a known form of sporadic CJD.IMPORTANCESince the quasi-extinction of classical BSE, atypical BSE forms are the sole BSE variants circulating in cattle worldwide. They are observed in rare cases of old cattle, making them difficult to detect. Extrapolation of our results suggests that L-BSE may propagate in humans as an unrecognized form of CJD, and we urge both the continued utilization of precautionary measures to eliminate these agents from the human food chain and active surveillance for CJD phenotypes in the general population.

Background Cerebrospinal fluid (CSF) biomarkers β-amyloid 1-42 (Aβ 1-42 ), also expressed as Aβ 1-42 :Aβ 1-40 ratio, T-tau, and P-tau 181P , have proven diagnostic accuracy for mild cognitive impairment and Alzheimer's disease (AD). How to use, interpret, and disclose biomarker results drives the need for standardization. Methods Previous Alzheimer's Biomarkers Standardization Initiative meetings discussed preanalytical issues affecting Aβ 1-42 and tau in CSF. This second round of consensus meetings focused on issues related to clinical use of AD CSF biomarkers. Results Consensus was reached that lumbar puncture for AD CSF biomarker analysis be considered as a routine clinical test in patients with early-onset dementia, at the prodromal stage or with atypical AD. Moreover, consensus was reached on which biomarkers to use, how results should be interpreted, and potential confounding factors. Conclusions Changes in Aβ 1-42 , T-tau, and P-tau 181P allow diagnosis of AD in its prodromal stage. Conversely, having all three biomarkers in the normal range rules out AD. Intermediate conditions require further patient follow-up.

International audience; We report the presence of infectivity in erythrocytes, leukocytes, and plasma of 1 person with variant Creutzfeldt-Jakob disease and in the plasma of 2 in 4 persons whose tests were positive for sporadic Creutzfeldt-Jakob disease. The measured infectivity levels were comparable to those reported in various animals with transmissible spongiform encephalopathies.

Background: Virtually nothing is known about a potential diagnostic role of non-phospho-epitopes of Tau (Non-P-Tau) in cerebrospinal fluid (CSF). Objective: To establish and analytically and clinically characterize the first assay capable to measure concentrations of Non-P-Tau in human CSF. Methods: An antibody (1G2) was developed that selectively binds to the Tau molecule non-phosphorylated at the positions T175 and T181, and was used in establishing a sandwich ELISA capable to measure Non-P-Tau in human CSF, following analytical and clinical validation of the method. Results: The 1G2 antibody shows decreasing reactivity to tau peptides containing phosphorylation mainly at positions T175 and T181. Detection limit of the assay is 25 pg/ml; the coefficients of variation (CVs) of the optical densities of the repeated standard curves were between 3.615.9%. Median intra-assay imprecision of double measurements was 4.8%; inter-assay imprecision was in the range of 11.2%15.3%. Non-P-Tau concentrations are stable in the CSF samples sent to distinct laboratories under ambient temperature; inter-laboratory variation was approximately 30%. The Non-P-Tau CSF concentrations were highly significantly increased in patients with Alzheimers disease in stage of mild cognitive impairment or dementia (AD/MCI, n = 58, 109.2±32.0 pg/mL) compared to the non-demented Controls (n = 42, 62.1±9.3 pg/mL, p < 0.001). At the cut-off of 78.3 pg/mL, the sensitivity and the specificity were 94.8% and 97.6%, respectively. Conclusion: For the first time, an assay is reported to reliably measure concentrations of non-phosphorylated Tau in human CSF. Keywords

International audience; We compared transmission characteristics for prions from L-type bovine spongiform encephalopathy and MM2-cortical sporadic Creutzfeldt-Jakob disease in the Syrian golden hamster and an ovine prion protein-transgenic mouse line and isolated distinct prion strains. Our findings suggest the absence of a causal relationship between these diseases, but further investigation is warranted.

This work illustrates the enhancement of the sensitivity of the ELISA titration for recombinant human and native prion proteins, while reducing other non-specific adsorptions that could increase the background signal and lead to a low sensitivity and false positives. It is achieved thanks to the association of plasma chemistry and coating with different amphiphilic molecules bearing either ionic charges and/or long hydrocarbon chains. The treated support by 3-butenylamine hydrochloride improves the signal detection of recombinant protein, while surface modification with the 3,7-dimethylocta-2,6-dien-1-diamine (geranylamine) enhances the sensitivity of the native protein. Beside the surface chemistry effect, these different results are associated with protein conformation.

New nonfouling tubes are developed and their influence on the adhesion of neuroproteins is studied. The biomarkers are considered as single components (recombinant prion and Tau proteins) or in a solution of native and pathological forms. The samples are stored for 24 h at 4 °C in virgin and treated tubes layered with two different nanostructured coatings based on poly(N-isopropylacrylamide) with either a positive or a neutral charge, and the protein adhesion is monitored. The recombinant protein with a high pI is repelled from the nanostructured surface that has a negative ζ potential, whereas the recombinant protein with the lower pI is attracted. Furthermore, in the case of complex solutions, neutral nanostructured surfaces are able to retain all amyloid biomarkers.

The inner polymeric surface of an ELISA titration well is plasma-modified and coated with different surfactant molecules. The titration of neurodegenerative proteins markers (prion, Tau and β-synuclein), previously demonstrated as more efficient with such modified tubes, is related to the adhesion behaviour of these proteins and their corresponding capture antibodies. The adhesion process is studied in terms of anchoring and specific mechanisms. The proteins and antibodies binding onto such modified surfaces is related to the substrate hydrophilic character calculated from the angle contact measure, to the polymer surface charge measured through the streaming potential determination at different pH and the inner surface roughness determined from AFM images. Furthermore, the influence of the blocking agent used during the ELISA titration is also studied.

New non-fouling tubes are developed and their influence on the adhesion of neuroproteins is studied. Recombinant prion proteins are considered as a single component representative of hydrophobic proteins. Samples are stored for 24 h at 4 °C in tubes coated with two different coatings: poly(N-isopropylacrylamide) as a hydrophilic surface and a plasma-fluorinated coating as a hydrophobic one. The protein adhesion is monitored by ELISA tests, XPS and confocal microscopy. It appears that the highest recovery of recombinant prion protein in the liquid phase is obtained with the hydrophilic surface while the hydrophobic character of the storage tube induces an important amount of biological loss. However, the recovery is not complete even for tubes coated with poly(N-isopropylacrylamide).

International audience; To improve the etiological diagnosis of neurodegenerative dementias like Alzheimer's disease (AD) or frontotemporal dementia (FTD), we evaluated the value of individual and combined measurements of the following relevant cerebrospinal fluid (CSF) biomarkers: Tau, 181p-Tau, Aβ38, Aβ40, Aβ42, sAβPPα, and sAβPPβ. This study conducted in two centers included patients with FTD (n = 34), AD (n = 52), as well as a control group of persons without dementia (CTRL, n = 42). Identical clinical criteria and pre-analytical conditions were used while CSF biomarkers were measured using commercial single and multiplex quantitative immunoassays. Thorough statistical analyses, including ROC curves, logistic regressions, and decision trees, were performed. We validated in AD the specific increase of p-Tau levels and the decrease of Aβ42 levels, two biological hallmarks of this disease. Tau concentrations were highest in AD and intermediate in FTD when compared to CTRL. The most interesting results were obtained by focusing on amyloid biomarkers as we found out in FTD a significant decrease of sAβPPβ, Aβ38, and Aβ40 levels. Aβ38 in particular was the most useful biomarker to differentiate FTD subjects from the CTRL population. Combining p-Tau and Aβ38 led us to correctly classifying FTD patients with sensitivity at 85% and specificity at 82%. Significant changes in amyloid biomarkers, particularly for Aβ38, are therefore seen in FTD. This could be quite useful for diagnosis purposes and it might provide additional evidence on the interrelationship between Tau and AβPP biology which understanding is essential to progress towards optimal therapeutic and diagnostic approaches of dementia.

Background Cerebral microdialysis is a valuable tool for neurochemical monitoring of acute brain injury. We performed an independent analytical validation of glucose, lactate and pyruvate methods on the new ISCUSflex new analyzer developed by CMA Microdialysis. Methods Evaluation of analytical parameters included limit of detection, limit of quantification, linearity, intra- and inter-assay imprecision expressed as the coefficient of variation (CV), recovery, inter-sample and inter-reagent contamination, drug and bilirubin interferences, sample stability, method comparison. Results Linearity ranges were 0.1–25 mmol/L, 0.2–12 mmol/L and 19–1500 μmol/L for glucose, lactate and pyruvate respectively. For critical threshold, intra- and inter-assay CVs were 3.1/4.5% for glucose (1 mmol/L), 3.5/4% for lactate (4 mmol/L) and 3.3/4.3% for pyruvate (100 μmol/L). Inter-assay CVs for lactate/pyruvate (LPR) and lactate/glucose (LGR) ratios were 5.9% and 6.0% respectively. For glucose, lactate, pyruvate, LPR and LGR, the reference change values (RCV) were 20%, 26%, 20%, 27% and 28% respectively. Practically, variations below 27% between two successive LPR values could not be interpreted as significant. Conclusion These data prove that ISCUSflex has the qualities required for clinical application in neuro-intensive care. Correct clinical interpretation of data need the implementation of a strict quality control program and strong cooperation between clinicians and biologists.