190 research outputs found
Vortex Waves and Channel Capacity: Hopes and Reality
Several recent contributions have envisioned the possibility of increasing
currently exploitable maximum channel capacity of a free space link, both at
optical and radio frequencies, by using vortex waves, i.e. carrying Orbital
Angular Momentum (OAM). Our objective is to disprove these claims by showing
that they are in contradiction with very fundamental properties of Maxwellian
fields. We demonstrate that the Degrees of Freedom (DoF) of the field cannot be
increased by the helical phase structure of electromagnetic vortex waves beyond
what can be done without invoking this property. We also show that the
often-advocated over-quadratic power decay of OAM beams with distance does not
play any fundamental role in the determination of the channel DoF.Comment: 8 pages, 7 figure
CSF neurofilament light concentration is increased in presymptomatic <i>CHMP2B </i>mutation carriers
Pathological differences observed in the presubiculum and entorhinal cortex in post-mortem Alzheimer's disease brain tissue
Lumbar and ventricular CSF concentrations of extracellular matrix proteins before and after shunt surgery in idiopathic normal pressure hydrocephalus
Background: Idiopathic normal pressure hydrocephalus (iNPH) is a reversible CNS disease characterized by disturbed cerebrospinal fluid (CSF) dynamics. Changes in the extracellular matrix (ECM) composition might be involved in the pathophysiology of iNPH. The aim of this study was to explore possible differences between lumbar and ventricular CSF concentrations of the ECM markers brevican and neurocan, matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinase-1 (TIMP-1) and their relation to clinical symptoms in iNPH patients before and after shunt surgery. Methods: Paired lumbar and ventricular CSF was collected from 31 iNPH patients, before and four months after shunt surgery. CSF was analysed for concentrations of tryptic peptides originating from brevican and neurocan using a mass spectrometry-based panel, and for MMP-1, -2, -9, -10 and TIMP-1 using fluorescent or electrochemiluminescent immunoassays. Results: Brevican and neurocan peptide levels were not influenced by CSF origin, but MMP-1, -2, -10 and TIMP-1 were increased (p ≤ 0.0005), and MMP-9 decreased (p ≤ 0.0003) in lumbar CSF compared with ventricular CSF. There was a general trend of ECM proteins to increase following shunt surgery. Ventricular TIMP-1 was inversely correlated with overall symptoms (rho = − 0.62, p < 0.0001). CSF concentrations of the majority of brevican and neurocan peptides were increased in iNPH patients with a history of cardiovascular disease (p ≤ 0.001, AUC = 0.84–0.94) compared with those without. Conclusion: Levels of the CNS-specific proteins brevican and neurocan did not differ between the lumbar and ventricular CSF, whereas the increase of several CNS-unspecific MMPs and TIMP-1 in lumbar CSF suggests contribution from peripheral tissues. The increase of ECM proteins in CSF following shunt surgery could indicate disturbed ECM dynamics in iNPH that are restored by restitution of CSF dynamics
Prediction of Outcome After Endovascular Embolectomy in Anterior Circulation Stroke Using Biomarkers
Stroke is a major public health problem that can cause a long-term disability or death due to brain damage. Serious stroke is frequently caused by a large vessel occlusion in the anterior circulation, which should be treated by endovascular embolectomy if possible. In this study, we investigated the use of the brain damage biomarkers tau, NFL, NSE, GFAp, and S100B to understand the progression of nervous tissue damage and their relationship to outcome in such stroke after endovascular treatment. Blood samples were taken from 90 patients pre-treatment and 2 h, 24 h, 48 h, 72 h and 3 months after endovascular treatment. Stroke-related neurological deficit was estimated using the National Institute of Health Stroke Scale (NIHSS) at admission and at 24 h. Neurological outcome was evaluated at 3 months. After stroke, tau, NFL, GFAp and S100B increased in a time dependent manner, while NSE remained constant over time. At 3 months, tau and GFAp levels were back to normal whereas NFL was still high. Tau, NFL and GFAp correlated well to outcome, as well as to infarct volume and NIHSS at 24 h. The best time for prediction of poor outcome was different for each biomarker. However, the combination of NIHSS at 24 h with either tau, NFL or GFAp at 48 h gave the best prediction. The use of biomarkers in the early setting after endovascular treatment of stroke will lead to a simplified and standardized way to estimate the nervous tissue damage and possibly complement the clinical judgement in foreseeing the need of rehabilitation measures
Is the presubiculum protected from neurodegenerative changes? A pathological and biochemical investigation
Neurofilaments can differentiate ALS subgroups and ALS from common diagnostic mimics
Delayed diagnosis and misdiagnosis are frequent in people with amyotrophic lateral sclerosis
(ALS), the most common form of motor neuron disease (MND). Neurofilament light chain (NFL) and
phosphorylated neurofilament heavy chain (pNFH) are elevated in ALS patients. We retrospectively
quantified cerebrospinal fluid (CSF) NFL, CSF pNFH and plasma NFL in stored samples that were
collected at the diagnostic work-up of ALS patients (n = 234), ALS mimics (n = 44) and controls (n = 9).
We assessed the diagnostic performance, prognostication value and relationship to the site of onset
and genotype. CSF NFL, CSF pNFH and plasma NFL levels were significantly increased in ALS patients
compared to patients with neuropathies & myelopathies, patients with myopathies and controls.
Furthermore, CSF pNFH and plasma NFL levels were significantly higher in ALS patients than in
patients with other MNDs. Bulbar onset ALS patients had significantly higher plasma NFL levels
than spinal onset ALS patients. ALS patients with C9orf72HRE mutations had significantly higher
plasma NFL levels than patients with SOD1 mutations. Survival was negatively correlated with all
three biomarkers. Receiver operating characteristics showed the highest area under the curve for CSF
pNFH for differentiating ALS from ALS mimics and for plasma NFL for estimating ALS short and long
survival. All three biomarkers have diagnostic value in differentiating ALS from clinically relevant ALS
mimics. Plasma NFL levels can be used to differentiate between clinical and genetic ALS subgroups
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