Proteomics and transcriptomics of peripheral nerve tissue and cells unravel new aspects of the human Schwann cell repair phenotype

The remarkable feature of Schwann cells (SCs) to transform into a repair phenotype turned the spotlight on this powerful cell type. SCs provide the regenerative environment for axonal re‐growth after peripheral nerve injury (PNI) and play a vital role in differentiation of neuroblastic tumors into a benign subtype of neuroblastoma, a tumor originating from neural crest‐derived neuroblasts. Hence, understanding their mode‐of‐action is of utmost interest for new approaches in regenerative medicine, but also for neuroblastoma therapy. However, literature on human SCs is scarce and it is unknown to which extent human SC cultures reflect the SC repair phenotype developing after PNI in patients. We performed high‐resolution proteome profiling and RNA‐sequencing on highly enriched human SC and fibroblast cultures, control and ex vivo degenerated nerve explants to identify novel molecules and functional processes active in repair SCs. In fact, we found cultured SCs and degenerated nerves to share a similar repair SC‐associated expression signature, including the upregulation of JUN, as well as two prominent functions, i.e., myelin debris clearance and antigen presentation via MHCII. In addition to myelin degradation, cultured SCs were capable of actively taking up cell‐extrinsic components in functional phagocytosis and co‐cultivation assays. Moreover, in cultured SCs and degenerated nerve tissue MHCII was upregulated at the cellular level along with high expression of chemoattractants and co‐inhibitory rather than ‐stimulatory molecules. These results demonstrate human SC cultures to execute an inherent program of nerve repair and support two novel repair SC functions, debris clearance via phagocytosis‐related mechanisms and type II immune‐regulation. GLIA 2016;64:2133–2153     

Depressive symptoms and muscular fitness contribute independently to the ability to perform daily life activities in people with bipolar disorder

Background: Compared with healthy controls, people with bipolar disorder experience muscle weakness. The extent to which muscle weakness influences the performance of daily life activities such as walking in people with bipolar disorder requiring hospitalization is unclear. Aims: The primary aim of the current study was to explore whether depressive symptoms and muscular fitness independently contribute to the walking capacity in people with bipolar disorder. A secondary aim was to identify variables that could explain the variability in muscular fitness. Methods: Forty-two inpatients with bipolar disorder performed a standing broad jump test (SBJ), a measure of muscular performance, and the six minute walk test (6MWT) in addition to the International Physical Activity Questionnaire (IPAQ), the Depressive Symptomatology Self Report (QIDS) and a full-fasting metabolic screening. Results: The correlation between the 6MWT (595.0?±?127.3m) and SBJ (126.2?±?48.6m) was high (r?=?0.72, p?Conclusions: Depressive symptoms and muscular fitness contribute independently to daily life functioning in people with bipolar disorder. Thus, muscular rehabilitation strategies might offer a strategy for improving performance of daily life activities in this group.     

Raising suspicion of maltreatment from burns: Derivation and validation of the BuRN-Tool

Background

10–25% of childhood burns arise from maltreatment.

Review on solving the forward problem in EEG source analysis

Background

The aim of electroencephalogram (EEG) source localization is to find the brain areas responsible for EEG waves of interest. It consists of solving forward and inverse problems. The forward problem is solved by starting from a given electrical source and calculating the potentials at the electrodes. These evaluations are necessary to solve the inverse problem which is defined as finding brain sources which are responsible for the measured potentials at the EEG electrodes.

Methods

While other reviews give an extensive summary of the both forward and inverse problem, this review article focuses on different aspects of solving the forward problem and it is intended for newcomers in this research field.

Results

It starts with focusing on the generators of the EEG: the post-synaptic potentials in the apical dendrites of pyramidal neurons. These cells generate an extracellular current which can be modeled by Poisson's differential equation, and Neumann and Dirichlet boundary conditions. The compartments in which these currents flow can be anisotropic (e.g. skull and white matter). In a three-shell spherical head model an analytical expression exists to solve the forward problem. During the last two decades researchers have tried to solve Poisson's equation in a realistically shaped head model obtained from 3D medical images, which requires numerical methods. The following methods are compared with each other: the boundary element method (BEM), the finite element method (FEM) and the finite difference method (FDM). In the last two methods anisotropic conducting compartments can conveniently be introduced. Then the focus will be set on the use of reciprocity in EEG source localization. It is introduced to speed up the forward calculations which are here performed for each electrode position rather than for each dipole position. Solving Poisson's equation utilizing FEM and FDM corresponds to solving a large sparse linear system. Iterative methods are required to solve these sparse linear systems. The following iterative methods are discussed: successive over-relaxation, conjugate gradients method and algebraic multigrid method.

Conclusion

Solving the forward problem has been well documented in the past decades. In the past simplified spherical head models are used, whereas nowadays a combination of imaging modalities are used to accurately describe the geometry of the head model. Efforts have been done on realistically describing the shape of the head model, as well as the heterogenity of the tissue types and realistically determining the conductivity. However, the determination and validation of the in vivo conductivity values is still an important topic in this field. In addition, more studies have to be done on the influence of all the parameters of the head model and of the numerical techniques on the solution of the forward problem.     

Clonal spread of fluoroquinolone non-susceptible Streptococcus pyogenes

BACKGROUND: Fluoroquinolones are an important group of antibiotics widely used in adults, and, despite the absence of official approval, these drugs are also used in children. So far, resistance to fluoroquinolones in Streptococcus pyogenes is very rare. METHODS: During a national surveillance programme in Belgium from 1999 to 2002, 2793 non-duplicate S. pyogenes recovered from tonsillopharyngitis patients were screened for fluoroquinolone resistance. Mutations in topoisomerase genes and the presence of any efflux pump activity were investigated to elucidate the fluoroquinolone resistance mechanisms. Clonality was assessed by pulsed-field gel electrophoresis (PFGE) and emm typing. RESULTS: Non-susceptibility to fluoroquinolones, defined as ciprofloxacin MIC > or = 2 mg/L, was identified in 152 (5.4%) of 2793 S. pyogenes. Fifty-five (36%) fluoroquinolone non-susceptible isolates were investigated for known resistance mechanisms; all showed mutations in parC, and 29 (19%) isolates also in parE; antibiotic efflux was not noted. Two major PFGE types comprised 88% of fluoroquinolone non-susceptible S. pyogenes and belonged to serotypes emm6 and emm75. Overall, emm6 and emm75 constituted >90% of all fluoroquinolone non-susceptible isolates and showed a significant temporal and geographical shift within Belgian provinces. Although fluoroquinolone-susceptible S. pyogenes also showed fluctuations in the predominant S. pyogenes serotypes, emm6 or emm75 were under-represented in this population. Approx. 55% of the fluoroquinolone non-susceptible isolates were recovered from children ( < or =16 years). CONCLUSIONS: We show here, for the first time, a multi-clonal spread of fluoroquinolone non-susceptible S. pyogenes exhibiting a known resistance mechanism. Non-susceptibility to fluoroquinolones in paediatric isolates is of concern.     

The frequency of seizures in patients with primary brain tumors or cerebral metastases. An evaluation from the Ludwig Boltzmann Institute of Neuro-Oncology and the Department of Neurology,Kaiser Franz Josef Hospital,Vienna

Epileptic seizures are common in patients with cerebral metastases as well as in patients with primary brain tumors. In cancer patients without primary brain tumors or brain metastasis, epileptic seizures may occur due to metabolic or toxic causes, or due to infections. We performed a retrospective analysis from our neurooncological database concerning the occurrence of seizures in patients with primary brain tumors, patients with cerebral metastases and in cancer patients without brain tumors. Patients with low grade gliomas, such as astrocytoma WHO I + II (69%), oligodendroglioma WHO II (50%), and mixed glioma WHO II-III (56%) were more likely to have seizures than patients with anaplastic glioma WHO III (44%), glioblastoma WHO IV (48%) or meningeoma (45%). In patients with brain metastasis, melanoma (67%), cancer of the lung (29%), and gastrointestinal tumors (21%) were the primaries with the highest frequency of seizures. In cancer patients without brain metastases or primary brain tumors, seizures occurred in 4%. In conclusion, the occurrence of epileptic seizures in patients suffering from primary brain tumors, as well as in patients with cerebral metastases, varied within the tumor entity. Therefore, especially in brain tumors where a higher probability of epileptic seizures is expected, they should be taken into account in the care of cancer patients.