Jan-Erik Karlsson

Patients with amyotrophic lateral sclerosis and other neurodegenerative diseases have increased levels of neurofilament protein in CSF.

Abstract: In the present study we describe an ELISA to quantify the light subunit of the neurofilament triplet protein (NFL) in CSF. The method was validated by measuring CSF NFL concentrations in healthy individuals and in two well‐characterized groups of patients with amyotrophic lateral sclerosis (ALS) and Alzheimers disease (AD). The levels were increased in ALS (1,743 ± 1,661 ng/L; mean ± SD) and AD (346 ± 176 ng/L) compared with controls (138 ± 31 ng/L; p < 0.0001 for both). Within the ALS group, patients with lower motor neuron signs only had lower NFL levels (360 ± 237 ng/L) than those with signs of upper motor neuron disease (2,435 ± 1,633 ng/L) (p < 0.05). In a second study patients with miscellaneous neurodegenerative diseases were investigated (vascular dementia, olivopontocerebellar atrophy, normal pressure hydrocephalus, cerebral infarctions, and multiple sclerosis), and the CSF NFL level was found to be increased (665 ± 385 ng/L; p < 0.0001). NFL is a main structural protein of axons, and we suggest that CSF NFL can be used to monitor neurodegeneration in general, but particularly in ALS with involvement of the pyramidal tract.

Microwave-Based Stroke Diagnosis Making Global Prehospital Thrombolytic Treatment Possible

Here, we present two different brain diagnostic devices based on microwave technology and the associated two first proof-of-principle measurements that show that the systems can differentiate hemorrhagic from ischemic stroke in acute stroke patients, as well as differentiate hemorrhagic patients from healthy volunteers. The system was based on microwave scattering measurements with an antenna system worn on the head. Measurement data were analyzed with a machine-learning algorithm that is based on training using data from patients with a known condition. Computer tomography images were used as reference. The detection methodology was evaluated with the leave-one-out validation method combined with a Monte Carlo-based bootstrap step. The clinical motivation for this project is that ischemic stroke patients may receive acute thrombolytic treatment at hospitals, dramatically reducing or abolishing symptoms. A microwave system is suitable for prehospital use, and therefore has the potential to allow significantly earlier diagnosis and treatment than today.

General Anesthesia Versus Conscious Sedation for Endovascular Treatment of Acute Ischemic Stroke

Background and Purpose— Retrospective studies have found that patients receiving general anesthesia for endovascular treatment in acute ischemic stroke have worse neurological outcome compared with patients receiving conscious sedation. In this prospective randomized single-center study, we investigated the impact of anesthesia technique on neurological outcome in acute ischemic stroke patients. Methods— Ninety patients receiving endovascular treatment for acute ischemic stroke in 2013 to 2016 were included and randomized to general anesthesia or conscious sedation. Difference in neurological outcome at 3 months, measured as modified Rankin Scale score, was analyzed (primary outcome) and early neurological improvement of National Institutes of Health Stroke Scale and cerebral infarction volume. Age, sex, comorbidities, admission National Institutes of Health Stroke Scale score, intraprocedural blood pressure, blood glucose, Paco2 and Pco2 modified Thrombolysis in Cerebral Ischemia score, and relevant time intervals were recorded. Results— In the general anesthesia group 19 of 45 patients (42.2%) and in the conscious sedation group 18 of 45 patients (40.0%) achieved a modified Rankin Scale score ⩽2 (P=1.00) at 3 months, with no differences in intraoperative blood pressure decline from baseline (P=0.57); blood glucose (P=0.94); PaCO2 (P=0.68); time intervals (P=0.78); degree of successful recanalization, 91.1% versus 88.9% (P=1.00); National Institutes of Health Stroke Scale score at 24 hours 8 (3–5) versus 9 (2–15; P=0.60); infarction volume, 20 (10–100) versus 20(10–54) mL (P=0.53); and hospital mortality (13.3% in both groups; P=1.00). Conclusions— In endovascular treatment for acute ischemic stroke, no difference was found between general anesthesia and conscious sedation in neurological outcome 3 months after stroke. Clinical Trial Registration— URL: https://www.clinicaltrials.gov. Unique identifier: NCT01872884.

Quantitative and Qualitative Alterations of Neuronal and Glial Intermediate Filaments in Rat Nervous System After Exposure to 2, 5‐Hexanedione

The precise mechanism for the neurotoxicity of 2, 5‐hexanedione is not known, but cross‐linking of neurofilament proteins has been suggested as one possibility. In this study the effects of long‐term exposure to 2, 5‐hexanedione were studied in the rat nervous system with special reference to regional changes in the quantities of neuronal and glial intermediate filaments. Using enzyme‐linked immunosorbent assays the concentrations of 68‐ and 200‐kDa neurofilament polypeptides were shown to be reduced in all brain regions studied. Similar results were obtained in the sciatic nerve. The concentration of glial fibrillary acidic protein was decreased in the cerebellar vermis and the dorsal cerebral cortex, whereas it was increased in the spinal cord, a result suggesting a regional variation in glial sensitivity. The intermediate filaments of the exposed animals were also immunoblotted using polyclonal antisera against the various neurofilament polypeptides and glial fibrillary acidic protein. In all tissues studied, several aggregates with molecular weights higher than those of the monomeric polypeptides were demonstrated. Contrary to clinical observations, these data indicate pronounced effects in both CNS and PNS and call for further studies on CNS effects in humans.

Hypotension During Endovascular Treatment of Ischemic Stroke Is a Risk Factor for Poor Neurological Outcome.

Background and Purpose— In retrospective studies, patients receiving general anesthesia for endovascular treatment for acute ischemic stroke have worse neurological outcome compared with patients receiving conscious sedation. It has been suggested that this is caused by general anesthesia–associated hypotension. We investigated the effect of intraprocedural hypotension on neurological outcome. Methods— One hundred eight patients with acute ischemic stroke, who underwent endovascular treatment in general anesthesia between 2007 and 2012, were included. Analyzed predictors of neurological outcome were age, sex, comorbidities, baseline National Institutes of Health Stroke Scale, intraprocedural relative changes in mean arterial blood pressure from baseline, blood glucose, modified Thrombolysis in Cerebral Infarction score, and elapsed time from stroke to computed tomography, groin puncture, and recanalization/end of procedure. Results— A fall in mean arterial blood pressure of >40% was an independent predictor for poor neurological outcome (P=0.032), as were higher admission National Institutes of Health Stroke Scale score (P=0.008) and lack of recanalization (P=0.003). Conclusions— Profound intraprocedural hypotension is an independent predictor for poor neurological outcome in patients with acute ischemic stroke undergoing endovascular therapy in general anesthesia.

Astroglial and neuronal proteins in cerebrospinal fluid as markers of CNS involvement in Lyme neuroborreliosis

Is Lyme neuroborreliosis, even in its early phase, a parenchymatous disorder in the central nervous system (CNS), and not merely a meningitic process? We quantified cerebrospinal fluid (CSF) levels of four nerve and glial cell marker proteins in Lyme neuroborreliosis patients with pretreatment durations of 7–240 days. AH 23 patients had meningo‐radiculitis, and six had objective signs of encephalopathy. Glial fibrillary acidic protein (GFAp) pretreatment levels in CSF, and the light subunit of neurofilament protein (NFL) levels were related to clinical outcome and declined significantly after treatment (P < 0.001 and P < 0.01, respectively). NFL was detectable in 11 out of 22 patients, and pre‐and post‐treatment NFL levels were associated with the duration of neurological symptoms within 100 days prior to treatment. Neuron‐specific enolase (NSE) concentrations also decreased after therapy (P < 0.001), while CSF levels of glial S‐100 protein remained unchanged. The pretreatment duration of disease was related to postinfectious sequelae. GFAp, NSE and NFL levels in CSF are unspecific indicators of astroglial and neuronal involvement in CNS disease. The findings in the present study are in agreement with the hypothesis that early and late stages of Lyme neuroborreliosis damage the CNS parenchyma.

A rapid HPLC method to separate the triplet proteins of neurofilament.

Abstract: In this article a fast HPLC technique to separate the individual neurofilament proteins is described. Highly pure fractions of the three neurofilament proteins can be obtained. As much as 50 mg of each neurofilament poly‐peptide can be separated from a crude neurofilament protein preparation in one step in less than 2 h. The short separation time is of importance in minimizing degradation, especially of the 150‐kilodalton neurofilament poly‐peptide.

Polyclonal Antisera to the Individual Neurofilament Triplet Protdins: A Characterization Using ELISA and Immunoblotting

In this article, the preparation and characterization of polyclonal rabbit antisera against the individual polypeptides of bovine neurofilament (68, 150, and 200 kilodaltons) is described. Selected antisera against the 68‐ add 150‐kilo‐dalton neurofilament polypeptides were specific for the corresponding antigen in homogenates of bovine, rat, and human brain as judged by immunoblots. The antisera against the 200‐kilodalton neurofilament polypeptide crossjreacted to some extent with the 150‐kilodalton neurofilament polypeptide, especially with the human antigen. The most specific antisera were used to develop an enzyme‐linked immunosorbent assay (ELISA), and the cross‐reactivities between the antisera and the different bovine and rat neurofilament polypeptides were determined. Contrary to the results In the immunoblots, the antiserum against the 200‐kilodalton neurofilament polypeptide was subunit‐specific, as was the 150‐kilodalton antiserum. The 68‐kilodalton antiserum displayed a minute cross‐reactivity against bovine 150‐ and 200‐kilodalton neurofilaments, but it cross‐reacted somewhat more with the rat 150‐ and 200‐kilodalton antigens. Even so, the subunit specificity of the antisera is high enough to enable the development of a quantitative ELISA for determination of the individual bovine or rat neurofilament polypeptides in a mixture. This study is the necessary preparation for such an assay.

Proteolysis of Filament Proteins in Glial and Neuronal Cells After' In vivo Stimulation of Hippocampal NMDA Receptors

An intrahippocampal injection of N-methyl-D-aspartate induced the appearance of degradation products of both the 68 kiloDalton neurofilament protein and the glial fibrillary acidic protein, as revealed by immunoblot techniques. The degradation of these two filament proteins was maximal at 10 days after the lession. The degradation patterns were similar to those induced with calpains or calcium in vitro. There were no degradation effects on the 200 kD neurofilament protein as tested with both mono- and polyclonal antibodies. Consequently, the neuronal degeneration after excessive activation of NMDA receptors appears to involve calcium activation of proteolytic enzymes. The effects on the glial proteins are probably secondary to neuronal damage but could be related to calcium dependent processes.

Phosphorylated and non-phosphorylated neurofilament proteins: distribution in the rat hippocampus and early changes after kainic acid induced seizures

The regional distribution of neurofilament proteins in the rat hippocampus and their early changes after kainic acid induced seizures were investigated immunocytochemically with antibodies against light weight neurofilament, phosphorylated and non-phosphorylated heavy weight neurofilament. The light weight and non-phosphorylated heavy weight neurofilaments were distributed more unevenly than the phosphorylated neurofilament. The perikarya and processes of pyramidal cells in the CA3 field contained the highest light weight and non-phosphorylated heavy weight neurofilaments, while the perikarya of granule cells contained only few light weight neurofilament and the perikarya of CA1 pyramidal cells were even devoid of immunoreactivity of both light and heavy weight neurofilaments. The fiber staining of the light weight and non-phosphorylated heavy weight neurofilaments, especially the former, was less in the CA1 field and molecular layer of dentate gyrus. The phosphorylated neurofilament immunoreactivity was identified only in axons. Mossy fibers, the axons of granule cells, contained the light weight and phosphorylated heavy weight neurofilaments, but not the non-phosphorylated neurofilament. Seven days after the kainic acid induced seizures, the phosphorylated neurofilament staining was greatly reduced in the CA1 and inner molecular layer of the dentate gyrus, probably resulting from the axonal degeneration of the Schaffer collaterals and the commissural/associational fibers. Furthermore, the nonphosphorylated neurofilament appeared in the mossy fibers of the CA3 stratum lucidum, which normally do not express such immunoreactivity. The results indicate that the neurofilaments are altered following the neuronal degeneration and postlesional plasticity caused by the kainic acid administration. Therefore, the examination of various phosphorylated neurofilaments may offer a comprehensive understanding of major hippocampal pathways, axonal plasticity and the possible roles of neurofilaments in the hippocampus following excitotoxic insults.