Johannes Albers | Universiteit Antwerpen (original) (raw)

Papers by Johannes Albers

Atrial fibrillation in stroke-free patients is associated with memory impairment and hippocampal ... more Atrial fibrillation in stroke-free patients is associated with memory impairment and hippocampal atrophy

Intensivmedizin up2date, 2011

Nomenklatur. Der Begriff "Schlaganfall" ist syndromatisch definiert als "akutes fokales neurologi... more Nomenklatur. Der Begriff "Schlaganfall" ist syndromatisch definiert als "akutes fokales neurologisches Defizit aufgrund einer umschriebenen Durchblutungsstörung des Gehirns" [1]. 80 % der Schlaganfälle werden von einem ischämischen Hirninfarkt verursacht, etwa 20 % von einer zerebralen Blutung (hämorrhagischer Hirninfarkt) [1]. Obwohl klinisch nicht voneinander zu unterscheiden, sind Therapie, Prognose und Sekundärprophylaxe dieser beiden Krankheitsentitäten verschieden. Synonyme für den Begriff "Schlaganfall" sind die Bezeichnungen "Hirninsult" und im Englischen "stroke"; die Bezeichnungen "Apoplex" oder "Hirnschlag" sind veraltet und sollten nicht mehr verwendet werden [1]. █ Von einem "flüchtigen Hirninsult" wird gesprochen, wenn das fokale neurologische Defizit innerhalb kurzer Zeitin der Regel innerhalb einiger Minuten bis zu 1 hvollständig rückläufig ist. Meist ist dann noch kein morphologisches Korrelat in der Bildgebung des Gehirns nachweisbar. █ Ein flüchtiger Hirninsult darf jedoch per definitionem bis zu 24 h dauern. Dann liegt aber trotz verschwundener Fokalsymptomatik meist doch ein Hirninfarkt vor. Mit "Hirninfarkt" oder "Hirnblutung" wird das morphologische Korrelat der Hirnparenchymnekrose und des klinischen Insults beschrieben, das nur bildgebend oder autoptisch/bioptisch zu sichern ist. Ein akutes fokales neurologisches Defizit aufgrund einer umschriebenen Durchblutungsstörung des Gehirns wird als Schlaganfall bezeichnet. Schlaganfälle können durch Hirnblutungen (hämorrhagischer Schlaganfall) oder Hirninfarkte (ischämischer Schlaganfall) entstehen. Epidemiologie. Weltweit ist der Schlaganfall eine der häufigsten Erkrankungen und eine der führenden Ursachen der Morbidität und Mortalität [2]. Die Inzidenz ischämischer Schlaganfälle beträgt 160-240/100 000 Einwohner [3]. Die Prävalenz zerebrovaskulärer Krankheiten wird auf 700-800/100 000 Einwohner geschätzt. Die Mortalität nach 1 Jahr beträgt durchschnittlich 25 %. Die Mortalität unterschiedlicher Schlaganfallarten und-subtypen weist erhebliche Unterschiede auf [3].

$Research paper thumbnail of Intravenous lacosamide—An effective add-on treatment of refractory status epilepticus$

Cerebrovascular Diseases, 2012

In patients with HUS-N, TCD showed only slightly increased blood flow velocities of basal brain a... more In patients with HUS-N, TCD showed only slightly increased blood flow velocities of basal brain arteries (table 1). However, the mean resistance index (RI) and in particular the mean pulsatility index (PI) were significantly increased in patients with HUS-N, compared to HUS patients without neurological symptoms (mean PI/RI 1.11/0.62 vs. PI/RI 0.72/0.48, p ! 0.001, Mann Whitney U test; table 1). The abnormalities declined after 6 days, corresponding to clinical improvement (table 1). Discussion The slightly increased blood flow velocities in conjunction with a significantly elevated PI and RI in HUS-N support findings from autopsy and animal studies, suggesting an Stx-mediated apoptosis and necrosis of endothelial cells as the hallmark of a toxic vasculopathy [1-4]. Stx-induced endothelial damage leading to breakdown of the blood-brain barrier causes swelling of the capillary bed and therefore increases the peripheral arterial resistance [1-4]. This explains the alterations of PI and RI of patients with HUS-N. The changes on TCD are specifically found in patients with neurological involvement compared to the normal findings in patients without neurological symptoms. The TCD investigations have been performed after onset of neurological symptoms, which is a limitation of the study. Therefore, a prediction of the HUS-related neurological symptoms by TCD was not possible. However, the first TCD of patient 1 showed only small changes of blood flow velocity, PI and RI, while initial TCD measurements of patients 2-4 revealed more substantial changes. In accordance with these findings, patients 2-4 suffered from massive neurological symptoms (table 1), even in the 6-day follow-up, while patient 1 initially experienced mild neurological involvement. Six days thereafter, the neurological status of patient 1 had become normal. Thus, clinical symptoms and changes of the TCD were parallel to a large extent; however, our case number is too small to draw definite conclusions on this finding.

PLOS ONE

To raise biodiversity awareness effectively, communicators should be aware of knowledge levels in... more To raise biodiversity awareness effectively, communicators should be aware of knowledge levels in their audiences. Species identification skills have been used in the past as a measure of what people know about species, yet it is not known whether they serve as good indicators. To study the link between species identification and in-depth species knowledge, we presented an animal knowledge test to an online audience of over 7,000 Dutch adults, and used correlation and regression analyses to determine the extent to which species identification predicts in-depth knowledge about species’ origin, habitat, diet, and behavior. We found that in-depth knowledge was higher in those who correctly identified species as compared with those who did not correctly identify species, for all four types of in-depth knowledge. Moreover, as compared to alternative variables (work, age, gender, and educational level), species identification was by far the best predictor for in-depth knowledge about spec...

The Anatomical Record, 1991

The present study deals with a light- and electron microscopic morphometric analysis of Golgi-imp... more The present study deals with a light- and electron microscopic morphometric analysis of Golgi-impregnated neurons in the superior colliculus of rats with the purpose to unravel inter- and intralaminar differences in their dendritic and synaptic organization. In particular, layer IV was studied and compared with its boundary layers III and V. The results show that collicular cells in layer IV basically form a homogeneous population with respect to the number of primary dendrites, the total length of impregnated dendrites, and the diameter, ellipticity, and orientation of dendritic fields and somata of Golgi-impregnated neurons. Somata of reconstructed small cells in layer III and IV as well as V have all a similar density of about 40 synaptic contacts per 100 microns2 surface. However, the cell bodies of large multipolar cells in layer V have a slightly but significantly larger synaptic density (about 50 per 100 microns2). Dendrites of large and small collicular cells had no significantly different synaptic densities (43 and 48 per 100 microns2, respectively). In conclusion, the present results show only minor dendritic and synaptic differences between individual cells in the same layer, as well as in neighboring layers, which implies a low degree of cellular and synaptic intra- and interlaminar differentiation. It is discussed that this organization differs markedly from that in other visual centers, including the collicular homologue, the tectum of lower vertebrates, and the mammalian visual cortex, where pronounced inter- and intralaminar differentiations exist. Such an organization may provide a framework of laminar specificity by which distinct cell types may select a restricted set of input out of all information available. The present quantitative investigation suggests that a similar framework is not present in the superior colliculus.

MEAN-LTP was assessed by the grand average of MEPs at time point T0 to T30 after PAS, no... more MEAN-LTP was assessed by the grand average of MEPs at time point T0 to T30 after PAS, normalized to the baseline MEP. Values >1 indicate responders, whereas values ≤1 indicate non-responders to PAS.</p

MMSE: Mini mental state examination, BDI: Beck’s depression inventory, SD: standard devi... more MMSE: Mini mental state examination, BDI: Beck’s depression inventory, SD: standard deviation; groups were compared using unpaired t-tests.</p

Error bars indicate standard error of the mean. * indicate significant differences betwe... more Error bars indicate standard error of the mean. * indicate significant differences between groups (p<0.05; uncorrected), # indicates significant differences from baseline within groups (p<0.05, uncorrected).</p

Influence of CEA on PAS-induced plasticity is indicated by the mean MEP-changes (MEAN-LT... more Influence of CEA on PAS-induced plasticity is indicated by the mean MEP-changes (MEAN-LTP). Three out of 9 patients responded to PAS with the expected MEP-increase before CEA, 2 patients responded to PAS 6 months after CEA (difference n. s.).</p

AVLT: Auditory verbal learning test, WMS: Wechsler memory scale; SD: standard deviation;... more AVLT: Auditory verbal learning test, WMS: Wechsler memory scale; SD: standard deviation; groups were compared using unpaired t-tests.</p

Klinische Neurophysiologie, 2007

MMSE: Mini mental state examination; BDI: Becks depression inventory; AVLT: Auditory ver... more MMSE: Mini mental state examination; BDI: Becks depression inventory; AVLT: Auditory verbal learning test; WMS: Wechsler memory scale; groups were compared using paired t-tests.</p

PloS one, 2012

Severe stenosis of the internal carotid artery (ICA) has been associated with impaired cognition ... more Severe stenosis of the internal carotid artery (ICA) has been associated with impaired cognition in patients, but its effect on rapid-onset cortical plasticity is not known. Carotid endarterectomy (CEA) in patients with severe ICA stenosis reduces stroke risk, but the impact on cognition or physiology of the respective hemisphere remains controversial. 16 patients with severe stenosis of the ICA and 16 age and sex matched controls were included. Rapid-onset cortical plasticity was assessed using the paired-associative stimulation (PAS) protocol. PAS models long-term synaptic potentiation in human motor cortex, combining repetitive stimulation of the peripheral ulnar nerve with transcranial magnetic stimulation of the contralateral motor cortex. Cognitive status was assessed with a neuropsychological test battery. In patients, verbal learning and rapid-onset cortical plasticity were significantly reduced as compared to controls. Identical follow-up tests in 9 of the 16 patients six m...

NeuroImage, 2010

Aphasia after middle cerebral artery (MCA) stroke shows highly variable degrees of recovery. One ... more Aphasia after middle cerebral artery (MCA) stroke shows highly variable degrees of recovery. One possible explanation may be offered by the variability of the occlusion location. Branches from the proximal portion of the MCA often supply the mesial temporal lobe including parts of the hippocampus, a structure known to be involved in language learning. Therefore, we assessed whether language recovery in chronic aphasia is dependent on the proximity of the MCA infarct and correlated with the integrity of the hippocampus and its surrounding white matter. Language reacquisition capability was determined after 2weeks of intensive language therapy and 8months after treatment in ten chronic aphasia patients. Proximity of MCA occlusion relative to the internal carotid artery was determined by magnetic resonance imaging (MRI) based on the most proximal anatomical region infarcted. Structural damage to the hippocampus was assessed by MRI-based volumetry, regional microstructural integrity of hippocampus adjacent white matter by fractional anisotropy. Language learning success for trained materials was correlated with the proximity of MCA occlusion, microstructural integrity of the left hippocampus and its surrounding white matter, but not with lesion size, overall microstructural brain integrity and a control region outside of the MCA territory. No correlations were found for untrained language materials, underlining the specificity of our results for training-induced recovery. Our results suggest that intensive language therapy success in chronic aphasia after MCA stroke is critically dependent on damage to the hippocampus and its surrounding structures.

Journal of Neuroimaging, 2010

BACKGROUND AND PURPOSE-The goal of this study was to explore the structural correlates of functio... more BACKGROUND AND PURPOSE-The goal of this study was to explore the structural correlates of functional language dominance by directly comparing the brain morphology of healthy subjects with left-and right-hemisphere language dominance. METHODS-Twenty participants were selected based on their language dominance from a cohort of subjects with known language lateralization. Structural differences between both groups were assessed by voxel-based morphometry, a technique that automatically identifies differences in the local gray matter volume between groups using high-resolution T1-weighted magnetic resonance images. RESULTS-The main findings can be summarized as follows: (1) Subjects with righthemisphere language dominance had significantly larger gray matter volume in the right hippocampus than subjects with left-hemisphere language dominance. (2) Leftward structural asymmetries in the posterior superior temporal cortex, including the planum temporale (PT), were observed in both groups. CONCLUSIONS-Our study does not support the still prevalent view that asymmetries of the PT are related in a direct way to functional language lateralization. The structural differences