Specific biomarkers for acute stroke: comparison between human and animal models and development of a new way to improve acute stroke conditions

© 2018 Dr. Marie DagonnierStroke is the third most common cause of death in most Western countries and the major cause of disability. The distinction between stroke subtypes and knowledge of the time of stroke onset is critical in clinical practice. The most specific and biologically powerful treatment for acute ischaemic stroke is thrombolysis with recombinant tissue plasminogen activator (rt-PA) given within the first 4.5 hours of ischaemic stroke onset but this therapy is disappointingly underused. This mainly because of unknown symptoms onset time and uncertainty about stroke diagnostic. Neuroimaging can help decide who and how to treat. Nevertheless, neuroimaging is expensive, has contra-indications and is not always readily available. Cheap and easily measured blood biomarkers serve similar roles for other diseases. The traditional approach to stroke biomarker discovery has been to select candidate markers based on their known involvement in the stroke pathophysiology. This “pick your best candidate” approach inevitably means selection from only a small pool of what is theoretically available. High throughput technologies such as whole genome microarrays and proteomics permit unbiased selection of molecular markers by examining all of genes and proteins expressed in a tissue. In this thesis, these agnostic approaches were used to identify characteristic blood RNA and protein expression profiles occurring after stroke. In the first chapters, we show that most acute stroke patients do not have the indicated imaging done in an appropriate time window, therefore blood biomarkers would have a useful niche. We also show that, to date, most candidate blood biomarkers have not found use in the clinic because they have been selected from experiments that do not address the rapidly changing nature of stroke and have been identified by an ad hoc process that only scratches the surface of the potential candidates available. A pilot gene array experiment performed in rats to specifically look for hyper-acute changes that might be clinically informative in a way not easily realizable in humans, identified gene expression changes of great amplitude which changed markedly with time. This indicated that it should be possible to generate a stroke clock for use in the clinic. A larger follow up confirmation experiment designed also to examine the influence of experimental comorbidities demonstrated that many of the changes could be attributed to the surgical intervention needed to induce stroke in rats. This has important implications for our understanding of stroke inflammatory biology and also suggests the need for a different approach to stroke biomarker discovery. Examination of protein expression in bloods from a clinical trial of hypothermia identified new candidate biomarkers. A clinical trial to examine blood RNA expression, ultimately performed as a pilot because of recruitment difficulties, was designed to examine temporal change. It confirmed that collection of sequential blood samples in a clinically relevant time frame is possible and identified time dependent gene expression with overlap with the rat data. This indicates that generation of a clinically useful stroke clock should indeed be possible

A case report of rigidity and recurrent lower limb myoclonus: progressive encephalomyelitis rigidity and myoclonus syndrome, a chameleon.

Progressive encephalomyelitis with rigidity and myoclonus (PERM) syndrome is a rare neurological condition. Its clinical characteristics include axial and limb muscle rigidity, myoclonus, painful spasms and hyperekplexia. Diagnosis of this disease can be very challenging and optimal long-term treatment is unclear.info:eu-repo/semantics/publishe

Mobilization after thrombolysis (rtPA) within 24 hours of acute stroke : what factors influence inclusion of patients in A Very Early Rehabilitation Trial (AVERT)?

Background: A key treatment for acute ischaemic stroke is thrombolysis (rtPA). However, treatment is not devoid of side effects and patients are carefully selected. AVERT (A Very Early Rehabilitation Trial), a large, ongoing international phase III trial, tests whether starting out of bed activity within 24 hours of stroke onset improves outcome. Patients treated with rtPA can be recruited if the physician allows (447 included to date). This study aimed to identify factors that might influence the inclusion of rtPA treated patients in AVERT. Methods: Data from all patients thrombolysed at Austin Health, Australia, between September 2007 and December 2011 were retrospectively extracted from medical records. Factors of interest included: demographic and stroke characteristics, 24 hour clinical response to rtPA treatment, cerebral imaging and process factors (day and time of admission). Results: 211 patients received rtPA at Austin Health and 50 (24%) were recruited to AVERT (AVERT). Of the 161 patients not recruited, 105 (65%) were eligible, and could potentially have been included (pot-AVERT). There were no significant differences in demographics, Oxfordshire classification or stroke severity (NIHSS) on admission between groups. Size and localization of stroke on imaging and symptomatic intracerebral heamorrhage rate did not differ. Patients included in AVERT showed less change in NIHSS 24 hours post rtPA (median change = 1, IQR (-1,4)) than those in the pot-AVERT group (median change = 3, IQR (0,6)) by the median difference of 2 points (95% CI: 0.3; p = 0.03). A higher proportion of rtPA treated AVERT patients were admitted on weekdays (p = 0.04). Linnea MujhlConclusion: Excluding a possible clinical instability, no significant clinical differences were identified between thrombolysed patients included in AVERT and those who were not. Over 500 AVERT patients will be treated with rtPA at trial end. These results suggest we may be able to generalize findings to other rtPA treated patients beyond the trial population

ForceAtlas2, a continuous graph layout algorithm for handy network visualization designed for the Gephi software

Gephi is a network visualization software used in various disciplines (social network analysis, biology, genomics...). One of its key features is the ability to display the spatialization process, aiming at transforming the network into a map, and ForceAtlas2 is its default layout algorithm. The latter is developed by the Gephi team as an all-around solution to Gephi users' typical networks (scale-free, 10 to 10,000 nodes). We present here for the first time its functioning and settings. ForceAtlas2 is a force-directed layout close to other algorithms used for network spatialization. We do not claim a theoretical advance but an attempt to integrate different techniques such as the Barnes Hut simulation, degree-dependent repulsive force, and local and global adaptive temperatures. It is designed for the Gephi user experience (it is a continuous algorithm), and we explain which constraints it implies. The algorithm benefits from much feedback and is developed in order to provide many possibilities through its settings. We lay out its complete functioning for the users who need a precise understanding of its behaviour, from the formulas to graphic illustration of the result. We propose a benchmark for our compromise between performance and quality. We also explain why we integrated its various features and discuss our design choices

Antiphospholipid syndrome-induced ischemic stroke following pembrolizumab: Case report and systematic review

Immune checkpoint inhibitors (ICI) improve the prognosis of patients with advanced non-small cell lung cancer. However, clinicians should be aware of potentially life-threatening immune-related adverse events (irAEs). We report a case of a 67-year-old man with lung adenocarcinoma who developed an acute ischemic stroke after the second administration of pembrolizumab. The patient benefited from thrombolysis and mechanical thrombectomy with improved neurological outcome. An anti-phospholipid syndrome (APS) was diagnosed. Simultaneously, he developed a grade IV autoimmune hepatitis. Both manifestations were considered irAEs and the ICI treatment was discontinued. Steroids were initiated resulting in irAEs resolution. Remarkably, the patient achieved a complete oncological response and persistent remission after one year follow-up despite early discontinuation of pembrolizumab. Of note, APS is rarely reported as irAE. To our knowledge, this is the first case reported in the context of lung cancer. A systematic review of the literature is provided.SCOPUS: re.jinfo:eu-repo/semantics/publishe

Effects of levetiracetam on the production of nitric oxide--an in vivo study.

Comparative StudyLetterinfo:eu-repo/semantics/publishe

Discovery and Longitudinal Evaluation of Candidate Biomarkers for Ischaemic Stroke by Mass Spectrometry-Based Proteomics

Application of acute therapies such as thrombolysis for ischaemic stroke (IS) is constrained because of diagnostic uncertainty and the dynamic nature of stroke biology. To investigate changes in blood proteins after stroke and as a result of thrombolysis treatment we performed label-free quantitative proteomics on serum samples using high-resolution mass spectrometry and long high-performance liquid chromatography gradient (5 hours) combined with a 50-cm column to optimise the peptide separation. We identified (false discovery rate [FDR]: 1%) and quantified a total of 574 protein groups from a total of 92 samples from 30 patients. Ten patients were treated by thrombolysis as part of a randomised placebo-controlled trial and up to 5 samples were collected from each individual at different time points after stroke. We identified 26 proteins differently expressed by treatment group (FDR: 5%) and significant changes of expression over time for 23 proteins (FDR: 10%). Molecules such as fibrinogen and C-reactive protein showed expression profiles with a high-potential clinical utility in the acute stroke setting. Protein expression profiles vary acutely in the blood after stroke and have the potential to allow the construction of a stroke clock and to have an impact on IS treatment decision making

Hyperacute changes in blood mRNA expression profiles of rats after middle cerebral artery occlusion: Towards a stroke time signature.

Stroke evolution is a highly dynamic but variable disease which makes clinical decision making difficult. Biomarker discovery programs intended to aid clinical decision making have however largely ignored the rapidity of stroke evolution. We have used gene array technology to determine blood mRNA expression changes over the first day after stroke in rats. Blood samples were collected from 8 male spontaneously hypertensive rats at 0, 1, 2, 3, 6 and 24h post stroke induction by middle cerebral artery occlusion. RNA was extracted from whole blood stabilized in PAXgene tubes and mRNA expression was detected by oligonucleotide Affymetrix microarray. Using a pairwise comparison model, 1932 genes were identified to vary significantly over time (p≤0.5x10(-7)) within 24h after stroke. Some of the top20 most changed genes are already known to be relevant to the ischemic stroke physiopathology (e.g. Il-1R, Nos2, Prok2). Cluster analysis showed multiple stereotyped and time dependent profiles of gene expression. Direction and rate of change of expression for some profiles varied dramatically during these 24h. Profiles with potential clinical utility including hyper acute or acute transient upregulation (with expression peaking from 2 to 6h after stroke and normalisation by 24h) were identified. We found that blood gene expression varies rapidly and stereotypically after stroke in rats. Previous researchers have often missed the optimum time for biomarker measurement. Temporally overlapping profiles have the potential to provide a biological "stroke clock" able to tell the clinician how far an individual stroke has evolved