Feasibility and accuracy of a voxel-based neuronavigation system with 3D image rendering in preoperative planning and as a learning tool for young neurosurgeons, exemplified by the anatomical localization of the superior sagittal sinus

It is essential for a neurosurgeon to know individual anatomy and the corresponding anatomical landmarks before starting a surgery. Continuous training, especially of young neurosurgeons, is crucial for understanding complex neuroanatomy. In this study, we used a neuronavigation system with 3D volumetric image rendering to determine the anatomical relationship between the sagittal suture and the superior sagittal sinus (SSS) in patients with intracranial lesions. Furthermore, we discussed the applicability of such system in preoperative planning, residency training, and research. The study included 30 adult patients (18 female/12 male) who underwent a cranial computed tomography (CT) scan combined with venous angiography, for preoperative planning. The position of the sagittal suture in relation to the SSS was assessed in 3D CT images using an image guidance system (IGS) with 3D volumetric image rendering. Measurements were performed along the course of the sagittal sinus at the bregma, lambda, and in the middle between these two points. The SSS deviated to the right side of the sagittal suture in 50% of cases at the bregma, and in 46.7% at the midpoint and lambda. The SSS was displaced to the left of the sagittal suture in 10% of cases at the bregma and lambda and in 13% at the midpoint. IGSs with 3D volumetric image rendering enable simultaneous visualization of bony surfaces, soft tissue and vascular structures and interactive modulation of tissue transparency. They can be used in preoperative planning and intraoperative guidance to validate external landmarks and to determine anatomical relationships. In addition, 3D IGSs can be utilized for training of surgical residents and for research in anatomy

Evaluation of the predictive value of intraoperative changes in motor evoked potentials of caudal cranial nerves for the postoperative functional outcome

Objective: In this present study, we investigated the predictive value of changes in intraoperatively acquired motor evoked potentials (MEPs) of the caudal cranial nerves CN.IX (glossopharyngeal nerve) and CN.XII (hypoglossal nerve) for the operative outcome. Methods: MEPs of the glossopharyngeal (CN.IX) and hypoglossal nerve (CN.XII) were recorded intraoperatively from 63 consecutive patients undergoing brain surgery. The collected data included the patient’s age, gender, diagnosis, positioning during surgery, MEP baseline, final and final- to- baseline MEP ratio of CN.IX and CN.XII and the contralateral abductor pollicis brevis muscle of the hand as a control as well as the pre- and postoperative nerve function of CN.IX and CN.XII. We correlated the changes of the MEPs to postoperative nerve function such as dysphagia, impairment of the gag reflex, uvula deviation, and tongue deviation. Results: For the glossopharyngeal nerve, we found a significant correlation between the amplitude (µV) of the final-to-baseline MEP ratio and uvula deviation (p=0.028) and the amplitude duration (ms) of the final MEP and gag reflex function (p=0.027). The analyses of the risk estimate revealed that patients with a final-to-baseline MEP ratio of the glossopharyngeal amplitude ≤ 1.47 V have a 3.4 times increased risk to develop a uvula deviation. Patients with a final MEP of the glossopharyngeal width ≤11.6 ms have a 3.6 times increased risk for their gag reflex to become extinct. For the hypoglossal nerve, we found a significant correlation between the amplitude width (ms) of the final-to-baseline MEP ratio and swallowing function (p=0.049). The analysis of the risk estimate revealed that patients with a final-to-baseline MEP ratio of the hypoglossal amplitude width ≤ 1.03 ms have a 1.5 times increased risk to develop dysphagia. Conclusion: In conclusion, our study greatly contributed to the current knowledge of intraoperative MEPs as a predictor for postoperative nerve function. We were able to extent previous findings on MEP values of the facial nerve on postoperative nerve function to two further cranial nerves. We could show a significant relationship between the MEP values of the glossopharyngeal nerve and postoperative function of the uvula and gag reflex. For the hypoglossal nerve, we were able to show a significant relationship between the MEP values and swallowing function. Furthermore, we observed a statistical trend for the correlation between the MEP values of the hypoglossal nerve and tongue deviation; further studies including a larger sample size could confirm this result. Finding reliable predictors for postoperative nerve function is of great importance to the overall quality of life for a patient undergoing brain surgery

Generation of Genetically-Modified Human Differentiated Cells for Toxicological Tests and the Study of Neurodegenerative Diseases

Human differentiated cell types, such as neurons or hepatocytes, are of limited availability, and their use for experiments requiring ectopic gene expression is challenging. Using the human conditionally-immortalized neuronal precursor line LUHMES, we explored whether genetic modification in the proliferating state could be used for experiments in the differentiated post-mitotic neurons. First, alpha-synuclein (ASYN), a gene associated with the pathology of Parkinson’s disease, was overexpressed. Increased amounts of the protein were tolerated without change of phenotype, and this approach now allows further studies on protein variants. Knockdown of ASYN attenuated the toxicity of the parkinsonian toxicant 1-methyl-4-phenylpyridinium (MPP+). Different lentiviral constructs then were tested: cells labeled ubiquitously with green (GFP) or red fluorescent protein (RFP) allowed the quantification of neurite growth and of its disturbance by toxicants; expression of proteins of interest could be targeted to different organelles; production of two different proteins from a single read-through construct was achieved successfully by an expression strategy using a linker peptide between the two proteins, which is cleaved by deubiquitinases; LUHMES, labeled with GFP in the cytosol and RFP in the mitochondria, were used to quantify mitochondrial mobility along the neurites. MPP+ reduced such organelle movement before any other detectable cellular change, and this toxicity was prevented by simultaneous treatment with the antioxidant ascorbic acid. Thus, a strategy has been outlined here to study new functional endpoints, and subtle changes of structure and proteostasis relevant in toxicology and biomedicine in post-mitotic human cells

Fine structure of sheet-webs of Linyphia triangularis (Clerck) and Microlinyphia pusilla (Sundevall), with remarks on the presence of viscid silk

We examined the webs of Linyphia triangularis (Clerck) and Microlinyphia pusilla (Sundevall) using light and scanning electronic microscopic techniques and compared them with the better known orb-webs. The linyphiid sheet-web consists of an unordered meshwork of fibres of different thicknesses. The sheet is connected to the scaffolding by the means of attachment discs. Thin threads with globules, which appear similar to the viscid silk droplets of orb-webs are present in most webs examined. Webs of M. pusilla had a higher density of these globules than did webs of L. triangularis. Webs of both species possess five types of thread connections and contain no aqueous glue for prey capture. Instead, unlike orb-webs, the sticky substances produced by the linyphiid aggregate glands cement the different layers and threads of the sheet by drying up after being produced. Due to the function, sheet webs may not require viscid silk, thereby leading to a more economic web. The assumption made in most previous studies, that the globules in linyphiid webs have the same properties and function as viscid silk in orb-webs, is unfounded

Transcriptional and metabolic adaptation of human neurons to the mitochondrial toxicant MPP⁺

Assessment of the network of toxicity pathways by Omics technologies and bioinformatic data processing paves the road toward a new toxicology for the twenty-first century. Especially, the upstream network of responses, taking place in toxicant-treated cells before a point of no return is reached, is still little explored. We studied the effects of the model neurotoxicant 1-methyl-4-phenylpyridinium (MPP+) by a combined metabolomics (mass spectrometry) and transcriptomics (microarrays and deep sequencing) approach to provide unbiased data on earliest cellular adaptations to stress. Neural precursor cells (LUHMES) were differentiated to homogeneous cultures of fully postmitotic human dopaminergic neurons, and then exposed to the mitochondrial respiratory chain inhibitor MPP+ (5 μM). At 18–24 h after treatment, intracellular ATP and mitochondrial integrity were still close to control levels, but pronounced transcriptome and metabolome changes were seen. Data on altered glucose flux, depletion of phosphocreatine and oxidative stress (e.g., methionine sulfoxide formation) confirmed the validity of the approach. New findings were related to nuclear paraspeckle depletion, as well as an early activation of branches of the transsulfuration pathway to increase glutathione. Bioinformatic analysis of our data identified the transcription factor ATF-4 as an upstream regulator of early responses. Findings on this signaling pathway and on adaptive increases of glutathione production were confirmed biochemically. Metabolic and transcriptional profiling contributed complementary information on multiple primary and secondary changes that contribute to the cellular response to MPP+. Thus, combined ‘Omics’ analysis is a new unbiased approach to unravel earliest metabolic changes, whose balance decides on the final cell fate