Homoarginine levels are regulated by L-arginine:glycine amidinotransferase and affect stroke outcome: results from human and murine studies.

BACKGROUND: Endogenous arginine homologues, including homoarginine, have been identified as novel biomarkers for cardiovascular disease and outcomes. Our studies of human cohorts and a confirmatory murine model associated the arginine homologue homoarginine and its metabolism with stroke pathology and outcome. METHODS AND RESULTS: Increasing homoarginine levels were independently associated with a reduction in all-cause mortality in patients with ischemic stroke (7.4 years of follow-up; hazard ratio for 1-SD homoarginine, 0.79 [95% confidence interval, 0.64-0.96]; P=0.019; n=389). Homoarginine was also independently associated with the National Institutes of Health Stroke Scale+age score and 30-day mortality after ischemic stroke (P<0.05; n=137). A genome-wide association study revealed that plasma homoarginine was strongly associated with single nucleotide polymorphisms in the L-arginine:glycine amidinotransferase (AGAT) gene (P<2.1 × 10(-8); n=2806), and increased AGAT expression in a cell model was associated with increased homoarginine. Next, we used 2 genetic murine models to investigate the link between plasma homoarginine and outcome after experimental ischemic stroke: (1) an AGAT deletion (AGAT(-/-)) and (2) a guanidinoacetate N-methyltransferase deletion (GAMT(-/-)) causing AGAT upregulation. As suggested by the genome-wide association study, homoarginine was absent in AGAT(-/-) mice and increased in GAMT(-/-) mice. Cerebral damage and neurological deficits in experimental stroke were increased in AGAT(-/-) mice and attenuated by homoarginine supplementation, whereas infarct size in GAMT(-/-) mice was decreased compared with controls. CONCLUSIONS: Low homoarginine appears to be related to poor outcome after ischemic stroke. Further validation in future trials may lead to therapeutic adjustments of homoarginine metabolism that alleviate stroke and other vascular disorders.

Neutralization of the IL-17 axis diminishes neutrophil invasion and protects from ischemic stroke.

The devastating effect of ischemic stroke is attenuated in mice lacking conventional and unconventional T cells, suggesting that inflammation enhances tissue damage in cerebral ischemia. We explored the functional role of αß and γδ T cells in a murine model of stroke and distinguished 2 different T cell-dependent proinflammatory pathways in ischemia-reperfusion injury. IFN-γ produced by CD4(+) T cells induced TNF-α production in macrophages, whereas IL-17A secreted by γδ T cells led to neutrophil recruitment. The synergistic effect of TNF-α and IL-17A on astrocytes resulted in enhanced secretion of CXCL-1, a neutrophil chemoattractant. Application of an IL-17A-blocking antibody within 3 hours after stroke induction decreased infarct size and improved neurologic outcome in the murine model. In autoptic brain tissue of patients who had a stroke, we detected IL-17A-positive lymphocytes, suggesting that this aspect of the inflammatory cascade is also relevant in the human brain. We propose that selective targeting of IL-17A signaling might provide a new therapeutic option for the treatment of stroke.

Brain perfusion SPECT in the presurgical evaluation of epilepsy: is additional ictal SPECT required in case of high-confidence lateralization of the seizure onset zone by interictal SPECT and vice versa?

BACKGROUND: Ictal brain perfusion SPECT provides higher sensitivity for the identification of the epileptic seizure onset zone (SOZ) than interictal SPECT. However, ictal SPECT is demanding due to the unpredictable waiting period for the next seizure to allow for ictal tracer injection. Thus, starting with an interictal scan and skipping the ictal scan if the interictal scan provides a SOZ candidate with high confidence could be an efficient approach. The current study estimated the rate of high-confidence SOZ candidates and the false lateralization rate among them for interictal and ictal SPECT. METHODS: 177 patients (48% females, median age 38y, interquartile range 27-48y) with ictal and interictal SPECT acquired with 99mTc-HMPAO (n = 141) or -ECD (n = 36) were included retrospectively. The vast majority of the patients was suspected to have temporal lobe epilepsy. Visual interpretation of the SPECT data was performed independently by 3 readers in 3 settings: "interictal only" (interictal SPECT and statistical hypoperfusion map), "ictal only" (ictal SPECT and hyperperfusion map), and "full" setting (side-by-side interpretation of ictal and interictal SPECT including statistical maps and SISCOM analysis). The readers lateralized the SOZ (right, left, none) and characterized their confidence using a 5-score. A case was considered "lateralizing with high confidence" if all readers lateralized to the same hemisphere with at least 4 of 5 confidence points. Lateralization of the SOZ in the "full" setting was used as reference standard. RESULTS: The proportion of "lateralizing with high confidence" cases was 4.5/31.6/38.4% in the "interictal only"/"ictal only"/"full" setting. One (12.5%) of the 8 cases that were "lateralizing with high confidence" in the "interictal only" setting lateralized to the wrong hemisphere. Among the 56 cases that were "lateralizing with high confidence" in the "ictal only" setting, 54 (96.4%) were also lateralizing in the "full" setting, all to the same hemisphere. CONCLUSIONS: Starting brain perfusion SPECT in the presurgical evaluation of epilepsy with an interictal scan to skip the ictal scan in case of a high-confidence interictal SOZ candidate is not a useful approach. In contrast, starting with an ictal scan to skip the interictal scan in case of a high-confidence ictal SOZ candidate can be recommended.

The neurological syndrome in adults during the 2011 northern German E. coli serotype O104:H4 outbreak.

The aim of this study was to describe the neurological syndrome in the largest cohort of adult patients with a complicated Shiga toxin-producing Escherichia coli infection. The recent outbreak of Shiga toxin-producing E. coli serotype O104:H4 in northern Germany affected more than 3842 patients, 22% of whom developed haemolytic uraemic syndrome. The proportion of adult patients was unusually high, and neurological complications were frequent and severe. In three hospitals, population-based evaluation of 217 patients with complicated Shiga toxin-producing E. coli infection was carried out, including neurological, neuroradiological, neurophysiological, cerebrospinal fluid and neuropathological analyses. Of the 217 patients with complicated Shiga toxin-producing E. coli infection, 104 (48%) developed neurological symptoms. Neurological symptoms occurred 5.3 days (mean) after first diarrhoea and 4 days after onset of haemolytic uraemic syndrome. Of the infected patients with neurological symptoms, 67.3% presented with cognitive impairment or aphasia. During the course of the disease, 20% of the patients developed epileptic seizures. The onset of neurological symptoms was paralleled by increases in blood urea nitrogen and serum creatinine. In 70 patients with cerebral magnetic resonance imaging, the most common findings were symmetrical hyperintensities in the region of abducens nucleus and lateral thalamus. On follow-up scans, these abnormalities were resolved. Neuropathological analysis revealed regionally accentuated astrogliosis and microgliosis, more predominant in the thalamus and brainstem than in the cortex, and neuronal expression of globotriaosylceramide. There were no signs of microbleeds, thrombotic vessel occlusion or ischaemic infarction. The neurological syndrome in adult patients with complicated Shiga toxin-producing E. coli infection is a rapidly progressive and potentially life-threatening disease necessitating intensive care unit treatment and intubation in >30% of cases. The outcome of neurological patients in the 2011 northern German Shiga toxin-producing E. coli O104:H4 outbreak was surprisingly good. Magnetic resonance imaging and neuropathological findings point to a mixed toxic and inflammatory pathomechanism leading to largely reversible damage of neuronal function.

Use of the mixed reality tool "VSI Patient Education" for more comprehensible and imaginable patient educations before epilepsy surgery and stereotactic implantation of DBS or stereo-EEG electrodes.

PURPOSE: It is unknown which patient education strategy before epilepsy surgery or stereotactic electrode implantation is best for patients. This prospective and randomized clinical study investigates whether the use of the mixed reality tool "VSI Patient Education" (VSI PE) running on HoloLens® glasses is superior to the use of a rubber brain model as a 3-dimensional tool for patient education before epilepsy surgery and stereotactic electrode implantation. MATERIAL AND METHODS: 17 patients with indication for epilepsy surgery or stereotactic electrode implantation were included in the study and randomized into two groups. All patients were informed with both comparative tools VSI PE (apoQlar®) and a rubber brain model (3B Scientific®) in a chronological order depending on group assignment. Afterwards, the patient and, if present, a relative (12) each filled out a questionnaire. For statistical analysis, Wilcoxon rank-sum tests were performed. RESULTS: Patients found their patient education highly significantly more comprehensible (p = 0.001**, r = 0.84) and almost significantly more imaginable (p=0.020, r = 0.57), when their doctor used VSI PE compared to the rubber brain model. The patients felt significantly less anxious as a result of VSI PE (p = 0.008*, r = 0.64). Highly significantly more patients chose VSI PE as the preferred patient education tool (p < 0.001**, r = 0.91), and almost significantly more patients decided VSI PE to be the future standard tool (p = 0.020, r = 0.56). Significantly more relatives chose VSI PE as the preferred patient education tool (p = 0.004*, r = 0.83), and significantly more relatives decided VSI PE to be the future standard tool (p = 0.002*, r = 0.91). CONCLUSION: VSI Patient Education is a promising new mixed reality tool for informing patients before epileptic surgery or stereotactic electrode implantation in order to enhance comprehension and imagination and reduce fear and worries. It might strengthen patient commitment and have a positive influence on patients' decisions in favor of medically indicated surgical operations.

Correction to: Routine diagnostics for neural antibodies, clinical correlates, treatment and functional outcome.

The original version of this article unfortunately contained a mistake.

Routine diagnostics for neural antibodies, clinical correlates, treatment and functional outcome.

OBJECTIVE: To determine frequencies, interlaboratory reproducibility, clinical ratings, and prognostic implications of neural antibodies in a routine laboratory setting in patients with suspected neuropsychiatric autoimmune conditions. METHODS: Earliest available samples from 10,919 patients were tested for a broad panel of neural antibodies. Sera that reacted with leucine-rich glioma-inactivated protein 1 (LGI1), contactin-associated protein-2 (CASPR2), or the voltage-gated potassium channel (VGKC) complex were retested for LGI1 and CASPR2 antibodies by another laboratory. Physicians in charge of patients with positive antibody results retrospectively reported on clinical, treatment, and outcome parameters. RESULTS: Positive results were obtained for 576 patients (5.3%). Median disease duration was 6 months (interquartile range 0.6-46 months). In most patients, antibodies were detected both in CSF and serum. However, in 16 (28%) patients with N-methyl-D-aspartate receptor (NMDAR) antibodies, this diagnosis could be made only in cerebrospinal fluid (CSF). The two laboratories agreed largely on LGI1 and CASPR2 antibody diagnoses (κ = 0.95). The clinicians (413 responses, 71.7%) rated two-thirds of the antibody-positive patients as autoimmune. Antibodies against the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR), NMDAR (CSF or high serum titer), γ-aminobutyric acid-B receptor (GABABR), and LGI1 had ≥ 90% positive ratings, whereas antibodies against the glycine receptor, VGKC complex, or otherwise unspecified neuropil had ≤ 40% positive ratings. Of the patients with surface antibodies, 64% improved after ≥ 3 months, mostly with ≥ 1 immunotherapy intervention. CONCLUSIONS: This novel approach starting from routine diagnostics in a dedicated laboratory provides reliable and useful results with therapeutic implications. Counseling should consider clinical presentation, demographic features, and antibody titers of the individual patient.

Neuropsychological outcome after complicated Shiga toxin-producing Escherichia coli infection.

BACKGROUND: The diarrhea associated hemolytic uremic syndrome (HUS) is a major cause of acute uremic failure in children, but not very common in adults. The enterohaemorrhagic Escherichia coli-epidemic in Germany in 2011 affected mostly young and healthy adults. While their immediate deficits have been published, not much is known about the time course and degree of recovery concerning cognitive and behavioral impairment. METHODS AND FINDINGS: Twenty patients with Shiga toxin-producing Escherichia coli infection and neurological symptoms underwent comprehensive neuropsychological assessment 3 months and 1 year after the acute disease. Overall, there was an excellent recovery of cognitive functions. In a detailed neuropsychological analysis no significant deficits could be noticed 1 year after the infection in terms of cognitive function, alertness, executive functions and speech. Interestingly there were no correlations between different indicators for severity of disease (hemoglobin and creatinine levels, days of hospitalization, neurological symptoms and MRI changes) and neuropsychological outcome. However, there were a small number of patients with limitations in every day and professional life even one year after the acute disease. CONCLUSIONS: Our study does not provide definitive answers regarding risk factors for these limitations. Still since Shiga toxin -producing Escherichia coli infection is a rare condition in adults, the information this study provides is important for the clinical practice. On one hand for consulting patients and on the other to raise the awareness of the physicians to possible long term complains and the consideration of neuropsychological assessment and supportive psychological treatment.

BDNF/TrkB signaling regulates HNK-1 carbohydrate expression in regenerating motor nerves and promotes functional recovery after peripheral nerve repair.

Functional recovery after peripheral nerve injury is often poor despite high regenerative capacity of peripheral neurons. In search for novel treatments, brief electrical stimulation of the acutely lesioned nerve has recently been identified as a clinically feasible approach increasing precision of axonal regrowth. The effects of this stimulation appear to be mediated by BDNF and its receptor, TrkB, but the down-stream effectors are unknown. A potential candidate is the HNK-1 carbohydrate known to be selectively reexpressed in motor but not sensory nerve branches of the mouse femoral nerve and to enhance growth of motor but not sensory axons in vitro. Here, we show that short-term low-frequency electrical stimulation (1 h, 20 Hz) of the lesioned and surgically repaired femoral nerve in wild-type mice causes a motor nerve-specific enhancement of HNK-1 expression correlating with previously reported acceleration of muscle reinnervation. Such enhanced HNK-1 expression was not observed after electrical stimulation in heterozygous BDNF or TrkB-deficient mice. Accordingly, the degree of proper reinnervation of the quadriceps muscle, as indicated by retrograde labeling of motoneurons, was reduced in TrkB+/- mice compared to wild-type littermates. Also, recovery of quadriceps muscle function, evaluated by a novel single-frame motion analysis approach, and axonal regrowth into the distal nerve stump, assessed morphologically, were considerably delayed in TrkB+/- mice. These findings indicate that BDNF/TrkB signaling is important for functional recovery after nerve repair and suggest that up-regulation of the HNK-1 glycan is linked to this phenomenon.

Carbohydrate mimics promote functional recovery after peripheral nerve repair.

OBJECTIVE: The outcome of peripheral nerve repair is often unsatisfactory, and efficient therapies are not available. We tested the therapeutic potential of functional mimics of the human natural killer cell glycan (3-sulfoglucuronyl beta1-3 galactoside) (HNK-1) epitope, a carbohydrate indicated to favor specificity of motor reinnervation in mice. METHODS: We applied a linear HNK-1 mimic peptide, scrambled peptide, or vehicle substances in polyethylene cuffs used to reconstruct the severed femoral nerves of adult mice. We used video-based motion analysis and morphological and tracing techniques to monitor the outcome of nerve repair. RESULTS: After glycomimetic application, quadriceps muscle function recovered to 93% of normal within 3 months. Restoration of function was less complete (71-76%) in control groups. Better functional recovery was associated with larger motoneuron somata, better axonal myelination in the quadriceps nerve, and enhanced precision of target reinnervation. Lesion-induced death of motoneurons was reduced by 20 to 25%. The glycomimetic enhanced survival and neurite outgrowth of both mouse and human motoneurons in vitro by 30 to 75%. Application of a novel cyclic glycomimetic also enhanced functional recovery in vivo. INTERPRETATION: The improved outcome of nerve repair after glycomimetic application may be attributed to neurotrophic effects. Our results hold promise for therapeutic use in humans.

Impacts of lesion severity and tyrosine kinase receptor B deficiency on functional outcome of femoral nerve injury assessed by a novel single-frame motion analysis in mice.

Functional recovery after peripheral nerve injury is often poor. Comprehension of cellular and molecular mechanisms limiting or promoting restoration of function and design of efficient therapeutic approaches remain serious challenges for neuroscience and medicine. Progress has been restricted by the lack of reliable methods for evaluation of motor functions in laboratory animals. We describe a novel approach for assessment of muscle function in mice after femoral nerve damage, an injury causing impairment of knee extension. The functional deficit can be precisely estimated by angle and distance measurements on single video frames recorded during movements of the animals with or without body weight support. Using this method we describe here the precise time-course and degree of functional recovery after femoral nerve crush and transection. In addition, we show that restoration of function is considerably impaired in mice with a reduced expression level of the tyrosine kinase receptor B, a cognate receptor for the neurotrophin brain-derived neurotrophic factor. This finding is consistent with known functions of brain-derived neurotrophic factor and tyrosine kinase receptor B and demonstrates the potential of the method. The principles of the approach are highly relevant for the development of novel functional assays in other peripheral and, in particular, central nervous system injury paradigms.