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Ziel dieser Arbeit ist es, anhand dreier quantitativer, systematischer Übersichtsarbeiten (Cochrane Reviews) die Möglichkeiten und Grenzen der EBM zu beleuchten. Dabei wird exemplarisch die Verwendung von hyperbarem Sauerstoff zur Therapie von chronischen Wunden, eines akuten ischämischen Schlaganfalls, sowie von Migräne- und Clusterkopfschmerzen untersucht.
During stroke the blood–brain barrier (BBB) is damaged which can result in vasogenic brain edema and inflammation. The reduced blood supply leads to decreased delivery of oxygen and glucose to affected areas of the brain. Oxygen and glucose deprivation (OGD) can cause upregulation of glucose uptake of brain endothelial cells. In this letter, we investigated the influence of MK801, a non-competitive inhibitor of the NMDA-receptor, on the regulation of the glucose uptake and of the main glucose transporters glut1 and sglt1 in murine BBB cell line cerebEND during OGD. mRNA expression of glut1 was upregulated 68.7- fold after 6 h OGD, which was significantly reduced by 10 μM MK801 to 28.9-fold. Sglt1 mRNA expression decreased during OGD which was further reduced by MK801. Glucose uptake was significantly increased up to 907% after 6 h OGD and was still higher (210%) after the 20 h reoxygenation phase compared to normoxia. Ten micromolar MK801 during OGD was able to reduce upregulated glucose uptake after OGD and reoxygenation significantly. Presence of several NMDAR subunits was proven on the mRNA level in cerebEND cells. Furthermore, it was shown that NMDAR subunit NR1 was upregulated during OGD and that this was inhibitable by MK801. In conclusion, the addition of MK801 during the OGD phase reduced significantly the glucose uptake after the subsequent reoxygenation phase in brain endothelial cells.
Background: Regular exercise is beneficial for cardiovascular health but a recent meta-analysis indicated a relationship between extensive endurance sport and a higher risk of atrial fibrillation, an independent risk factor for stroke. However, data on the frequency of cardiac arrhythmias or (clinically silent) brain lesions during and after marathon running are missing.
Methods/Design: In the prospective observational "Berlin Beat of Running" study experienced endurance athletes underwent clinical examination (CE), 3 Tesla brain magnetic resonance imaging (MRI), carotid ultrasound imaging (CUI) and serial blood sampling (BS) within 2-3 days prior (CE, MRI, CUI, BS), directly after (CE, BS) and within 2 days after (CE, MRI, BS) the 38\(^{th}\) BMW BERLIN-MARATHON 2011. All participants wore a portable electrocardiogram (ECG)-recorder throughout the 4 to 5 days baseline study period. Participants with pathological MRI findings after the marathon, troponin elevations or detected cardiac arrhythmias will be asked to undergo cardiac MRI to rule out structural abnormalities. A follow-up is scheduled after one year.
Results: Here we report the baseline data of the enrolled 110 athletes aged 36-61 years. Their mean age was 48.8 \(\pm\) 6.0 years, 24.5% were female, 8.2% had hypertension and 2.7% had hyperlipidaemia. Participants have attended a mean of 7.5 \(\pm\) 6.6 marathon races within the last 5 years and a mean of 16 \(\pm\) 36 marathon races in total. Their weekly running distance prior to the 38\(^{th}\) BMW BERLIN-MARATHON was 65 \(\pm\) 17 km. Finally, 108 (98.2%) Berlin Beat-Study participants successfully completed the 38\(^{th}\) BMW BERLIN-MARATHON 2011.
Discussion: Findings from the "Berlin Beats of Running" study will help to balance the benefits and risks of extensive endurance sport. ECG-recording during the marathon might contribute to identify athletes at risk for cardiovascular events. MRI results will give new insights into the link between physical stress and brain damage.
Background: Randomized controlled trials (RCT) on the treatment of severe space-occupying infarction of the middle cerebral artery (malignant MCA infarction) showed that early decompressive hemicraniectomy (DHC) is life saving and improves outcome without promoting most severe disablity in patients aged 18-60 years. It is, however, unknown whether the results obtained in the randomized trials are reproducible in a broader population in and apart from an academical setting and whether hemicraniectomy has been implemented in clinical practice as recommended by national and international guidelines. In addition, they were not powered to answer further relevant questions, e. g. concerning the selection of patients eligible for and the timing of hemicraniectomy. Other important issues such as the acceptance of disability following hemicraniectomy, the existence of specific prognostic factors, the value of conservative therapeutic measures, and the overall complication rate related to hemicraniectomy have not been sufficiently studied yet. Methods/Design: DESTINY-R is a prospective, multicenter, open, controlled registry including a 12 months follow-up. The only inclusion criteria is unilateral ischemic MCA stroke affecting more than 50% of the MCA-territory. The primary study hypothesis is to confirm the results of the RCT (76% mRS <= 4 after 12 months) in the subgroup of patients additionally fulfilling the inclusion cirteria of the RCT in daily routine. Assuming a calculated proportion of 0.76 for successes and a sample size of 300 for this subgroup, the width of the 95% CI, calculated using Wilson's method, will be 0.096 with the lower bound 0.709 and the upper bound 0.805. Discussion: The results of this study will provide information about the effectiveness of DHC in malignant MCA infarction in a broad population and a real-life situation in addition to and beyond RCT. Further prospectively obtained data will give crucial information on open questions and will be helpful in the plannig of upcomming treatment studies.
The long-term effects of enzyme-replacement therapy (ERT) in Fabry disease are unknown. Thus, the aim of this study was to determine whether ERT in patients with advanced Fabry disease affects progression towards 'hard' clinical end-points in comparison with the natural course of the disease.
METHODS:
A total of 40 patients with genetically proven Fabry disease (mean age 40 ± 9 years; n = 9 women) were treated prospectively with ERT for 6 years. In addition, 40 subjects from the Fabry Registry, matched for age, sex, chronic kidney disease stage and previous transient ischaemic attack (TIA), served as a comparison group. The main outcome was a composite of stroke, end-stage renal disease (ESRD) and death. Secondary outcomes included changes in myocardial left ventricular (LV) wall thickness and replacement fibrosis, change in glomerular filtration rate (GFR), new TIA and change in neuropathic pain.
RESULTS:
During a median follow-up of 6.0 years (bottom and top quartiles: 5.1, 7.2), 15 events occurred in 13 patients (n = 7 deaths, n = 4 cases of ESRD and n = 4 strokes). Sudden death occurred (n = 6) only in patients with documented ventricular tachycardia and myocardial replacement fibrosis. The annual progression of myocardial LV fibrosis in the entire cohort was 0.6 ± 0.7%. As a result, posterior end-diastolic wall thinning was observed (baseline, 13.2 ± 2.0 mm; follow-up, 11.4 ± 2.1 mm; P < 0.01). GFR decreased by 2.3 ± 4.6 mL min(-1) per year. Three patients experienced a TIA. The major clinical symptom was neuropathic pain (n = 37), and this symptom improved in 25 patients. The event rate was not different between the ERT group and the untreated (natural history) group of the Fabry Registry.
CONCLUSION:
Despite ERT, clinically meaningful events including sudden cardiac death continue to develop in patients with advanced Fabry disease.
A high load of white matter lesions and enlarged basilar arteries have been shown in selected patients with Fabry disease, a disorder associated with an increased stroke risk. We studied a large cohort of patients with Fabry disease to differentially investigate white matter lesion load and cerebral artery diameters. We retrospectively analyzed cranial magnetic resonance imaging scans of 87 consecutive Fabry patients, 20 patients with ischemic stroke, and 36 controls. We determined the white matter lesion load applying the Fazekas score on fluid-attenuated inversion recovery sequences and measured the diameters of cerebral arteries on 3D-reconstructions of the time-of-flight-MR-angiography scans. Data of different Fabry patient subgroups (males – females; normal – impaired renal function) were compared with data of patients with stroke and controls. A history of stroke or transient ischemic attacks was present in 4/30 males (13%) and 5/57 (9%) females with Fabry disease, all in the anterior circulation. Only one man with Fabry disease showed confluent cerebral white matter lesions in the Fazekas score assessment (1%). Male Fabry patients had a larger basilar artery (p<0.01) and posterior cerebral artery diameter (p<0.05) compared to male controls. This was independent of disease severity as measured by renal function and did not lead to changes in arterial blood flow properties. A basilar artery diameter of >3.2 mm distinguished between men with Fabry disease and controls (sensitivity: 87%, specificity: 86%, p<0.001), but not from stroke patients. Enlarged arterial diameters of the posterior circulation are present only in men with Fabry disease independent of disease severity.
Despite the obvious clinical significance of post-stroke angiogenesis in aged subjects, a detailed transcriptomic analysis of post-stroke angiogenesis has not yet been undertaken in an aged experimental model. In this study, by combining stroke transcriptomics with immunohistochemistry in aged rats and post-stroke patients, we sought to identify an age-specific gene expression pattern that may characterize the angiogenic process after stroke. We found that both young and old infarcted rats initiated vigorous angiogenesis. However, the young rats had a higher vascular density by day 14 post-stroke. “New-for-stroke” genes that were linked to the increased vasculature density in young animals included Angpt2, Angptl2, Angptl4, Cib1, Ccr2, Col4a2, Cxcl1, Lef1, Hhex, Lamc1, Nid2, Pcam1, Plod2, Runx3, Scpep1, S100a4, Tgfbi, and Wnt4, which are required for sprouting angiogenesis, reconstruction of the basal lamina (BL), and the resolution phase. The vast majority of genes involved in sprouting angiogenesis (Angpt2, Angptl4, Cib1, Col8a1, Nrp1, Pcam1, Pttg1ip, Rac2, Runx1, Tnp4, Wnt4); reconstruction of a new BL (Col4a2, Lamc1, Plod2); or tube formation and maturation (Angpt1, Gpc3, Igfbp7, Sparc, Tie2, Tnfsf10), had however, a delayed upregulation in the aged rats. The angiogenic response in aged rats was further diminished by the persistent upregulation of “inflammatory” genes (Cxcl12, Mmp8, Mmp12, Mmp14, Mpeg1, Tnfrsf1a, Tnfrsf1b) and vigorous expression of genes required for the buildup of the fibrotic scar (Cthrc1, Il6ra, Il13ar1, Il18, Mmp2, Rassf4, Tgfb1, Tgfbr2, Timp1). Beyond this barrier, angiogenesis in the aged brains was similar to that in young brains. We also found that the aged human brain is capable of mounting a vigorous angiogenic response after stroke, which most likely reflects the remaining brain plasticity of the aged brain.
Stabilization of the blood-brain barrier during and after stroke can lead to less adverse outcome. For elucidation of underlying mechanisms and development of novel therapeutic strategies validated in vitro disease models of the blood-brain barrier could be very helpful. To mimic in vitro stroke conditions we have established a blood-brain barrier in vitro model based on mouse cell line cerebEND and applied oxygen/glucose deprivation (OGD). The role of astrocytes in this disease model was investigated by using cell line C6. Transwell studies pointed out that addition of astrocytes during OGD increased the barrier damage significantly in comparison to the endothelial monoculture shown by changes of transendothelial electrical resistance as well as fluorescein permeability data. Analysis on mRNA and protein levels by qPCR, western blotting and immunofluorescence microscopy of tight junction molecules claudin-3,-5,-12, occludin and ZO-1 revealed that their regulation and localisation is associated with the functional barrier breakdown. Furthermore, soluble factors of astrocytes, OGD and their combination were able to induce changes of functionality and expression of ABC-transporters Abcb1a (P-gp), Abcg2 (bcrp), and Abcc4 (mrp4). Moreover, the expression of proteases (matrixmetalloproteinases MMP-2, MMP-3, MMP-9, and t-PA) as well as of their endogenous inhibitors (TIMP-1, TIMP-3, PAI-1) was altered by astrocyte factors and OGD which resulted in significant changes of total MMP and t-PA activity. Morphological rearrangements induced by OGD and treatment with astrocyte factors were confirmed at a nanometer scale using atomic force microscopy. In conclusion, astrocytes play a major role in blood-brain barrier breakdown during OGD in vitro.
Background and Purpose
In animal models, von Willebrand factor (VWF) is involved in thrombus formation and propagation of ischemic stroke. However, the pathophysiological relevance of this molecule in humans, and its potential use as a biomarker for the risk and severity of ischemic stroke remains unclear. This study had two aims: to identify predictors of altered VWF levels and to examine whether VWF levels differ between acute cerebrovascular events and chronic cerebrovascular disease (CCD).
Methods
A case–control study was undertaken between 2010 and 2013 at our University clinic. In total, 116 patients with acute ischemic stroke (AIS) or transitory ischemic attack (TIA), 117 patients with CCD, and 104 healthy volunteers (HV) were included. Blood was taken at days 0, 1, and 3 in patients with AIS or TIA, and once in CCD patients and HV. VWF serum levels were measured and correlated with demographic and clinical parameters by multivariate linear regression and ANOVA.
Results
Patients with CCD (158±46%) had significantly higher VWF levels than HV (113±36%, P<0.001), but lower levels than AIS/TIA patients (200±95%, P<0.001). Age, sex, and stroke severity influenced VWF levels (P<0.05).
Conclusions
VWF levels differed across disease subtypes and patient characteristics. Our study confirms increased VWF levels as a risk factor for cerebrovascular disease and, moreover, suggests that it may represent a potential biomarker for stroke severity, warranting further investigation.
Background: Population-based data, which continuously monitors time trends in stroke epidemiology are limited. We investigated the incidence of pathological and etiological stroke subtypes over a 16 year time period. Methods: Data were collected within the Erlangen Stroke Project (ESPro), a prospective, population-based stroke register in Germany covering a total study population of 105,164 inhabitants (2010). Etiology of ischemic stroke was classified according to the Trial of Org 10172 in Acute Stroke Treatment (TOAST) criteria. Results: Between January 1995 and December 2010, 3,243 patients with first-ever stroke were documented. The median age was 75 and 55% were females. The total stroke incidence decreased over the 16 year study period in men (Incidence Rate Ratio 1995-1996 vs. 2009-2010 (IRR) 0.78; 95% CI 0.58-0.90) but not in women. Among stroke subtypes, a decrease in ischemic stroke incidence (IRR 0.73; 95% CI 0.57-0.93) and of large artery atherosclerotic stroke (IRR 0.27; 95% CI 0.12-0.59) was found in men and an increase of stroke due to small artery occlusion in women (IRR 2.33; 95% CI 1.39-3.90). Conclusions: Variations in time trends of pathological and etiological stroke subtypes were found between men and women that might be linked to gender differences in the development of major vascular risk factors in the study population.
Background:
Oral anticoagulant therapy (OAT) potently prevents strokes in patients with atrial fibrillation. Vitamin K antagonists (VKA) have been the standard of care for long-term OAT for decades, but non-VKA oral anticoagulants (NOAC) have recently been approved for this indication, and raised many questions, among them their influence on medication adherence. We assessed adherence to VKA and NOAC in secondary stroke prevention.
Methods:
All patients treated from October 2011 to September 2012 for ischemic stroke or transient ischemic attack with a subsequent indication for OAT, at three academic hospitals were entered into a prospective registry, and baseline data and antithrombotic treatment at discharge were recorded. At the 1-year follow-up, we assessed the adherence to different OAT strategies and patients' adherence to their respective OAT. We noted OAT changes, reasons to change treatment, and factors that influence persistence to the prescribed OAT.
Results:
In patients discharged on OAT, we achieved a fatality corrected response rate of 73.3% (n=209). A total of 92% of these patients received OAT at the 1-year follow-up. We observed good adherence to both VKA and NOAC (VKA, 80.9%; NOAC, 74.8%; P=0.243) with a statistically nonsignificant tendency toward a weaker adherence to dabigatran. Disability at 1-year follow-up was an independent predictor of lower adherence to any OAT after multivariate analysis, whereas the choice of OAT did not have a relevant influence.
Conclusion:
One-year adherence to OAT after stroke is strong (>90%) and patients who switch therapy most commonly switch toward another OAT. The 1-year adherence rates to VKA and NOAC in secondary stroke prevention do not differ significantly between both therapeutic strategies.
Fragestellung
Die Prognose eines akuten Hirninfarktes bei Verschluss einer proximalen Hirnarterie ist trotz der intravenösen Thrombolyse mit rtPA ungünstig. Kann die kombinierte pharmaco-mechanische Rekanalisation von proximalen Gefäßverschlüssen bei akutem Hirninfarkt zu einer Verbesserung des klinischen Ergebnisses führen?
Methoden
Wir analysierten retrospektiv 66 konsekutiv aufgenommene Patienten (36m, 30w; mittleres Alter 61 Jahre (23-86 Jahre), die von 2010 bis 2012 kombiniert pharmako-mechanisch intra-arteriell behandelt wurden. 32 Patienten wiesen einen kombinierten ACI-/M1-Verschluss, 23 einen M1-Verschluss und 11 eine Basilaristhrombose auf. Mittlerer NIHSS lag bei 23. 57 Patienten erhielten eine kombinierte pharmaco-mechanische Therapie, 3 Patienten wurden lediglich pharmakologisch und 6 Patienten rein mechanisch rekanalisiert. Rekanalisierung bei 35 Patienten mit einem Stent-Retriever (32 Patienten mit pREset, 3 Patienten mit SOLITAIRE) erfolgt. Bei 46 Patienten wurde rtPA und bei 32 Patienten Tirofiban als Bridging Verfahren eingesetzt. Eine Stentanlage erfolgte in 28,78% der Fälle.
Ergebnisse
Die erzielten Rekanalisationsraten lagen bei 89,4% bei einer mittleren Dauer der Intervention von 96 Minuten (53,03% unter 90 Min.). Ein günstiges klinisches Ergebnis nach mRS (mRS 0-2) wurde bei 48% der Patienten erreicht. Die Rate an symptomatischen intrazerebralen Blutungen lag bei 4,55%. Die Mortalität war 19,7%. Die multivariate Regressionsanalyse ergab als modifizierbare Prediktoren für ein günstiges Outcome die Dauer bis zur Rekanalisation und die Gabe von rtPA.
Schlussfolgerungen
Die kombinierte endovaskuläre pharmako-mechanische Therapie kann die Mortalität und Morbidität von Schlaganfallpatienten mit Verschlüssen einer proximalen Hirnarterie reduzieren.
Background
Fabry disease (FD) is an X-linked multisystemic disorder with a heterogeneous phenotype. Especially atypical or late-onset type 2 phenotypes present a therapeutical dilemma.
Methods
To determine the clinical impact of the alpha-Galactosidase A (GLA) p.A143T/ c.427G > A variation, we retrospectively analyzed 25 p.A143T patients in comparison to 58 FD patients with other missense mutations.
Results
p.A143T patients suffering from stroke/ transient ischemic attacks had slightly decreased residual GLA activities, and/or increased lyso-Gb3 levels, suspecting FD. However, most male p.A143T patients presented with significant residual GLA activity (~50 % of reference), which was associated with normal lyso-Gb3 levels. Additionally, p.A143T patients showed less severe FD-typical symptoms and absent FD-typical renal and cardiac involvement in comparison to FD patients with other missense mutations. Two tested female p.A143T patients with stroke/TIA did not show skewed X chromosome inactivation. No accumulation of neurologic events in family members of p.A143T patients with stroke/transient ischemic attacks was observed.
Conclusions
We conclude that GLA p.A143T seems to be most likely a neutral variant or a possible modifier instead of a disease-causing mutation. Therefore, we suggest that p.A143T patients with stroke/transient ischemic attacks of unknown etiology should be further evaluated, since the diagnosis of FD is not probable and subsequent ERT or chaperone treatment should not be an unreflected option.
Die Rolle von Chronophin bei Schlaganfall-induziertem Funktionsverlust der Blut-Hirn-Schranke
(2018)
Der ischämische Schlaganfall ist mit einer jährlichen Inzidenz von 200/100 000 Einwohnern die häufigste Gefäßerkrankung in Deutschland. Atherothrombose, arterielle Hypertonie und Embolien unterschiedlichen Ursprungs sind die wesentlichen Ursachen des ischämischen Schlaganfalls. Die neurologischen Defizite nach einem Schlaganfall resultieren aus einem gestörten zerebralen Blutfluss und somit einer insuffizienten Sauerstoffversorgung. Zusätzlich ist die Ödembildung, welche von einer gesteigerten Permeabilität der Blut-Hirn-Schranke verursacht wird, am neuronalen Zelltod beteiligt.
Chronophin ist eine Aktinzytoskelett-regulierende Serin-Phosphatase. In einem ischämischen Schlaganfall-Modell konnte im Rahmen dieser Arbeit gezeigt werden, dass der globale Verlust von Chronophin zu einer vermehrten Ödembildung und einem aggravierten neurologischen Zustand der Mäuse im Vergleich zu wildtypischen Kontrollen führte. Hirnlysate von wildtypischen Mäusen zeigten verringerte Chronophin-Level in der vom Schlaganfall betroffenen Hemisphäre. Jedoch konnten initiale immunhistochemische und zellbiologische Untersuchungen weder Chronophin-abhängige Veränderungen der Blut-Hirn-Schranke feststellen noch einen zerebralen Zelltyp identifizieren, der für den schützenden Effekt von Chronophin verantwortlich ist.
Diese Ergebnisse weisen auf einen komplexen, vielzelligen Mechanismus hin, dem die schützende Rolle von Chronophin im ischämischen Schlaganfall unterliegt. Die Entschlüsselung dieses Mechanismus ist Aufgabe künftiger Untersuchungen.
Even as medical data sets become more publicly accessible, most are restricted to specific medical conditions. Thus, data collection for machine learning approaches remains challenging, and synthetic data augmentation, such as generative adversarial networks (GAN), may overcome this hurdle. In the present quality control study, deep convolutional GAN (DCGAN)-based human brain magnetic resonance (MR) images were validated by blinded radiologists. In total, 96 T1-weighted brain images from 30 healthy individuals and 33 patients with cerebrovascular accident were included. A training data set was generated from the T1-weighted images and DCGAN was applied to generate additional artificial brain images. The likelihood that images were DCGAN-created versus acquired was evaluated by 5 radiologists (2 neuroradiologists [NRs], vs 3 non-neuroradiologists [NNRs]) in a binary fashion to identify real vs created images. Images were selected randomly from the data set (variation of created images, 40%-60%). None of the investigated images was rated as unknown. Of the created images, the NRs rated 45% and 71% as real magnetic resonance imaging images (NNRs, 24%, 40%, and 44%). In contradistinction, 44% and 70% of the real images were rated as generated images by NRs (NNRs, 10%, 17%, and 27%). The accuracy for the NRs was 0.55 and 0.30 (NNRs, 0.83, 0.72, and 0.64). DCGAN-created brain MR images are similar enough to acquired MR images so as to be indistinguishable in some cases. Such an artificial intelligence algorithm may contribute to synthetic data augmentation for "data-hungry" technologies, such as supervised machine learning approaches, in various clinical applications.
This paper describes the estimation of the body weight of a person in front of an RGB-D camera. A survey of different methods for body weight estimation based on depth sensors is given. First, an estimation of people standing in front of a camera is presented. Second, an approach based on a stream of depth images is used to obtain the body weight of a person walking towards a sensor. The algorithm first extracts features from a point cloud and forwards them to an artificial neural network (ANN) to obtain an estimation of body weight. Besides the algorithm for the estimation, this paper further presents an open-access dataset based on measurements from a trauma room in a hospital as well as data from visitors of a public event. In total, the dataset contains 439 measurements. The article illustrates the efficiency of the approach with experiments with persons lying down in a hospital, standing persons, and walking persons. Applicable scenarios for the presented algorithm are body weight-related dosing of emergency patients.
Der Schlaganfall ist eine Krankheit mit großer Bedeutung, sowohl für die Betroffenen wie auch unter volkswirtschaftlichen Gesichtspunkten. In der Erforschung neuer und besserer Therapiemethoden für den ischämischen Schlaganfall ist ein gutes in-vitro-Modell der Blut-Hirn-Schranke unerlässlich, da ein Teil der Schädigung des ZNS durch einen Zusammenbruch dieser Barriere verursacht wird.
Die hCMEC/D3-Zelllinie stellt ein solches Modell dar; mit steigender Dauer der ischämischen Stoffwechsellage zeigt sich eine Erhöhung der LDH-Konzentration als Marker für das Absterben der Zellen sowie ein Rückgang der Zellvitalität. Zudem lässt sich eine Entzündungsreaktion mit Anstieg der Marker TNF-Alpha und VEGF, sowie tendenziell auch von Interleukin 6 und Interleukin 8 beobachten, welche auch auf eine Barriereschwächung hindeutet. Aus vorherigen Versuchen bekannte Tight junctions-Proteine wie Claudin 1 und Occludin waren in D3-Zellen unter ischämischen Bedingungen nicht verändert, Claudin 5 war in der PCR vermindert exprimiert. Die für die Barriereschwächung verantwortlichen Strukturproteine müssen durch weitere Versuche identifiziert werden. Eine mögliche Erhöhung der Expression des Transkriptionsfaktors ZO-1 könnte unter diesen Bedingungen einen Mechanismus der Barriereschwächung darstellen.
Die Expression des Glukokortikoidrezeptors war in Monokultur-Versuchen mit D3-Zellen nach Ischämie erniedrigt. Dies stellt eine Gemeinsamkeit mit Versuchen mit Zelllinien tierischen Ursprungs dar; in diesen zeigten die Zellen durch Degradation des Glukokortikoidrezeptors ein fehlendes Ansprechen auf eine Glukokortikoid-Behandlung. In der Cokultur der D3-Zellen mit Gliomzellen der C6-Zelllinie zeigte sich jedoch eine Erhöhung der GR-Expression. Eine Cokultur kann den komplexen Aufbau der Blut-Hirn-Schranke, mit Beteiligung mehrerer Zelltypen, besser darstellen als Versuche mit nur einer Zelllinie. Die Erhöhung der GR-Expression in diesem humanen in-vitro-Modell der Blut-Hirn-Schranke steht im Gegensatz zu den in-vitro-Versuchen mit anderen Zelllinien. Dies könnte eine mögliche Erklärung liefern, warum die Erkenntnisse aus diesen Versuchen bisher nicht zu einer Verbesserung der Evidenz der Glukokortikoid-Therapie beim ischämischen Schlaganfall beigetragen haben. Zudem zeigt die Fluoreszenzfärbung von D3-Zellen, dass diese auch unter Ischämie auf Glukokortikoide reagieren.
Background
The impact of risk factors on poor outcome after ischemic stroke is well known, but estimating the amount of poor outcome attributable to single factors is challenging in presence of multimorbidity. We aim to compare population attributable risk estimates obtained from different statistical approaches regarding their consistency. We use a real-life data set from the PROSCIS study to identify predictors for mortality and functional impairment one year after first-ever ischemic stroke and quantify their contribution to poor outcome using population attributable risks.
Methods
The PROSpective Cohort with Incident Stroke (PROSCIS) is a prospective observational hospital-based cohort study of patients after first-ever stroke conducted independently in Berlin (PROSCIS-B) and Munich (PROSCIS-M). The association of baseline factors with poor outcome one year after stroke in PROSCIS-B was analysed using multiple logistic regression analysis and population attributable risks were calculated, which were estimated using sequential population attributable risk based on a multiple generalized additive regression model, doubly robust estimation, as well as using average sequential population attributable risk. Findings were reproduced in an independent validation sample from PROSCIS-M.
Results
Out of 507 patients with available outcome information after 12 months in PROSCIS-B, 20.5% suffered from poor outcome. Factors associated with poor outcome were age, pre-stroke physical disability, stroke severity (NIHSS), education, and diabetes mellitus. The order of risk factors ranked by magnitudes of population attributable risk was almost similar for all methods, but population attributable risk estimates varied markedly between the methods. In PROSCIS-M, incidence of poor outcome and distribution of baseline parameters were comparable. The multiple logistic regression model could be reproduced for all predictors, except pre-stroke physical disability. Similar to PROSCIS-B, the order of risk factors ranked by magnitudes of population attributable risk was almost similar for all methods, but magnitudes of population attributable risk differed markedly between the methods.
Conclusions
Ranking of risk factors by population impact is not affected by the different statistical approaches. Thus, for a rational decision on which risk factor to target in disease interventions, population attributable risk is a supportive tool. However, population attributable risk estimates are difficult to interpret and are not comparable when they origin from studies applying different methodology. The predictors for poor outcome identified in PROSCIS-B have a relevant impact on mortality and functional impairment one year after first-ever ischemic stroke.