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Objective: Motor-evoked potentials (MEPs) after navigated transcranial magnetic stimulation (nTMS) are mirroring the status of the complete human motor system, far beyond corticospinal integrity. Classic time domain features of MEPs (e.g. peak-to-peak amplitudes and onset latencies) exert a high inter-subject[for full text, please go to the a.m. URL], 72. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), Joint Meeting mit der Polnischen Gesellschaft für Neurochirurgie

Objective: There is an increasing interest in preoperative diffusion tensor imaging fiber tracking (DTI-FT) to preserve function during operations in motor eloquent brain regions. However, DTI tractography is challenged by inherent presumptions (e.g. fractional anisotropy, angulation, fiber length thresholds,[for full text, please go to the a.m. URL], 69. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), Joint Meeting mit der Mexikanischen und Kolumbianischen Gesellschaft für Neurochirurgie

Objective: The combined use of intraoperative high-field MRI (iMRI) and electrophysiological monitoring (IOM) is often not applied on a routine basis due to concerns on possible side-effects. This is mainly based on sorrow to leave the skin-electrodes in-situ for intraoperative scanning, as burnings[for full text, please go to the a.m. URL], 68. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), 7. Joint Meeting mit der Society of British Neurological Surgeons (SBNS)

OECD Guidance Document 34 will be briefly recapitulated in context of special requirements for validation of alternative methods to predict inhalative toxicity. Selection of promising endpoints, standardization, optimization, assessment of variability within and between laboratories, and over time, as well as the development of a prediction model (PM) can be performed according to GD 34. However, final testing under blind conditions is often hampered by necessary analytics. Moreover, technically challenging analytics may have to be shared between labs in a rotating principle. Since each in vitro exposure experiment only provides one data point of a concentration-response, the number of test items employed has to be significantly lower than in other validation studies. We are reporting about a BMBF-funded study in four laboratories aiming at prevalidation of a methodology exposing human lung epithelial cells (A549) with toxic gases at the air/liquid interface. Using four reference gases in phase1 as a training set, both endpoints (cell viability and Comet genotoxicity) showed promising robustness; and a linear prediction model for acute in vivo toxicity could be developed. In phase2, the data set was enlarged by six gases (one overlap), and both, reproducibility and the PM of the training set could be independently confirmed.

Objective: Closed spinal dysraphism warrants primary or secondary surgical intervention. Surgery nowadays is expected to cause no neurological deterioration, regardless of the existence or absence of pre-operative deficits. Extended intraoperative monitoring (eIOM) is often used to reduce the risk of[for full text, please go to the a.m. URL], 65. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC)

In acute inhalation toxicity studies, animals inhale substances at given concentrations. Without additional information, it is difficult to estimate the appropriate starting concentration for in vivo inhalation studies. The goal of this BMBF funded project was the standardization and pre-validation of precision cut lung slices (PCLS) as a suitable ex vivo alternative approach to reduce animal numbers used in inhalation toxicology. The project was conducted in three independent laboratories (Fraunhofer ITEM, BASF SE, RWTH Aachen). BfR provided support in biostatistics. In all participating laboratories, rat PCLS were prepared and exposed to 20 substances under standard submerged culture conditions for 1 hour. Toxicity was assessed by measurement of released lactate dehydrogenase (LDH assay) and mitochondrial activity (WST-1 assay) after 23 hours post-incubation. In addition, protein content and IL-1 were measured. For all endpoints a sigmoid dose-response model was fitted to the data and IC50 values were calculated. This study shows the final results for all 20 chemicals. More than 900 dose-response curves were fitted and analysed. Log10[IC50 (M)] obtained for all assay endpoints showed best intra-laboratory consistency for the data obtained by WST-1 and BCA assays. While WST-1 and LDH indicated toxic effects for majority of the substances, only few of the substances induced increase in IL-1. The reproducibility within the participating laboratories appeared to have acceptably low between-laboratory variations for WST-1 and BCA assay. The results show (i) that the test protocol used in this study is adequately transferable for practical use and (ii) that the tissue model using the WST-1 endpoint is reliable. Binary prediction model showed promising results.

Introduction: For acute inhalation toxicity studies, animals inhale chemicals. At the beginning it is difficult to estimate non-toxic doses for in vivo inhalation. In the context of REACH and the principle of 3Rs, there is a public demand for alternative methods. The goal of this BMBF-funded project is the pre-validation of PCLS as a suitable ex vivo alternative model to replace pre-studies of inhalation toxicology. The project is conducted in three independent laboratories. BfR provides support in biostatistics. Methods: In all participating laboratories, PCLS were prepared and exposed to 5 concentrations of industrial chemicals in DMEM under standard culture conditions for 1 hour. After post-incubation, chemical-induced toxicity was assessed by LDH and WST-1 assay. In addition, PCLS protein content and pro-inflammatory cytokine IL-1alpha were measured by BCA assay and ELISA, respectively. For all endpoints a sigmoid dose-response model was fitted to the data and EC50 values were calculated. Test acceptance criteria were established for each endpoint. Results: This study shows the results of the first 6 tested substances out of 20. In all laboratories, concentration dependent toxicity could be shown for aniline, glutaraldehyde, triton X-100 and paracetamol, but not for lactose and methyl methacrylate. EC50-values obtained for the WST-1, LDH and BCA data were very similar in all participating laboratories. No increase in IL-1alpha was observed for these chemicals. Conclusion: Local respiratory toxicity induced by chemicals could be tested with comparable results in the PCLS model without in vivo experiments in three independent laboratories. The standardization of the PCLS method was successful and the reproducibility of the results is very promising after testing of the first 6 substances.

Information requirement on acute inhalation toxicity study is mandatory for substances in different regulatory contexts. There is a demand for alternative methods according to the principles of the 3Rs (reduction, refinement and replacement). Precision cut lung slices (PCLuS) is an ex vivo model currently pre-validated in a BMBF-funded projects. It can be used as screening method and to aid the selection of starting concentrations for acute inhalation studies. The project is conducted in three independent laboratories (Fraunhofer ITEM, BASF SE, RWTH Aachen; BfR (Bundesinstitut für Risikobewertung) provides biostatistics support. In all participating laboratories, PCLuS were prepared and exposed to 5 concentrations of industrial chemicals under standardized culture conditions for 1 hour. Afterwards, the medium containing test substance was replaced by fresh medium and the PCLuS was incubated for further 23 hours. Chemical-induced toxicity was assessed by LDH and WST-1 assay. In addition, protein content of the PCLuS and pro-inflammatory cytokine IL-1alpha (intra- and extracellular) were measured by BCA assay and ELISA, respectively. For all endpoints a sigmoid dose-response model was fitted to the data and EC50 values were calculated. Test acceptance criteria were established for each endpoint. The results of the first 6 test substances out of 20 are presented here: In all laboratories, concentration-related toxicity could be shown for aniline, glutaraldehyde, triton X-100 and paracetamol, but not for lactose and methyl methacrylate. EC50-values obtained for the WST-1, LDH and BCA data were very similar in all participating aboratories. No increase in IL-1alpha was observed for these chemicals at all tested concentrations. The standardization of the PCLuS method was successful and the reproducibility of the results is very promising after testing of the first 6 substances. This study was supported by the German BMBF [project number 0315720 A-C]

Objective: Cavernous malformations (CM) are low-flow vascular malformations. However, these lesions can cause severe neurological symptoms and deficits when hemorrhaging within the brainstem (BS). Removal of BS CMs has been associated with a high surgical morbidity, and there is no general consent especially[for full text, please go to the a.m. URL], 64. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC)

Objective: In this study we investigated the predictive value of changes in intraoperatively acquired motor evoked potentials (MEPs) of the lower cranial nerves IX-X (glossopharyngeal nerve and vagus nerve) and XII (hypoglossal nerve) for the postoperative functional outcome. Method: MEPs of CN IX[for full text, please go to the a.m. URL], 64. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC)

Objective: Pre-surgical access to locate the motor areas of the brain cortex represents a great advantage for successful neurosurgical functional preservation. Traditionally, functional magnetic resonance imaging (fMRI) with diffusion tensor imaging (DTI) technique has been used to study cortical motor[for full text, please go to the a.m. URL], 63. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), Joint Meeting mit der Japanischen Gesellschaft für Neurochirurgie (JNS)

Objective: Silent periods (SP's) in the neurophysiological assessment of Syringomyelia have been introduced with satisfactory results, giving early confirmation of disrupted spinothalamic fibers that convey pain and sensation. However the ability of the SP's to recover after resolution of [for full text, please go to the a.m. URL], 63. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), Joint Meeting mit der Japanischen Gesellschaft für Neurochirurgie (JNS)

Contact allergies are complex diseases, and one of the important challenges for public health and immunology. The German ‘Federal Institute for Risk Assessment’ hosted an ‘International Workshop on Contact Dermatitis’. The scope of the workshop was to discuss new discoveries and developments in the field of contact dermatitis. This included the epidemiology and molecular biology of contact allergy, as well as the development of new in vitro methods. Furthermore, it considered regulatory aspects aiming to reduce exposure to contact sensitisers. An estimated 15–20% of the general population suffers from contact allergy. Workplace exposure, age, sex, use of consumer products and genetic predispositions were identified as the most important risk factors. Research highlights included: advances in understanding of immune responses to contact sensitisers, the importance of autoxidation or enzyme-mediated oxidation for the activation of chemicals, the mechanisms through which hapten-protein conjugates are formed and the development of novel in vitro strategies for the identification of skin-sensitising chemicals. Dendritic cell cultures and structure-activity relationships are being developed to identify potential contact allergens. However, the local lymph node assay (LLNA) presently remains the validated method of choice for hazard identification and characterisation. At the workshop the use of the LLNA for regulatory purposes and for quantitative risk assessment was also discussed. peerReviewed

Object. Several studies have revealed that the gross-total resection (GTR) of malignant brain tumors has a significant influence on patient survival. Frequently, however, GTR cannot be achieved because the borders between healthy brain and diseased tissue are blurred in the infiltration zones of malignant brain tumors. Especially in eloquent cortical areas, resection is frequently stopped before total removal is achieved to avoid causing neurological deficits. Interestingly, 5-aminolevulinic acid (5-ALA) has been shown to help visualize tumor tissue intraoperatively and, thus, can significantly improve the possibility of achieving GTR of primary malignant brain tumors. The aim of this study was to go one step further and evaluate the utility and limitations of fluorescence-guided resections of primary malignant brain tumors in eloquent cortical areas in combination with intraoperative monitoring based on multimodal functional imaging data. Methods. Eighteen patients with primary malignant brain tumors in eloquent areas were included in this prospective study. Preoperative neuroradiological examinations included MR imaging with magnetization-prepared rapid gradient echo (MPRAGE), functional MR, and diffusion tensor imaging sequences to visualize functional areas and fiber tracts. Imaging data were analyzed offline, loaded into a neuronavigational system, and used intraoperatively during resections. All patients received 5-ALA 6 hours before surgery. Fluorescence-guided tumor resections were combined with intraoperative monitoring and cortical as well as subcortical stimulation to localize functional areas and fiber tracts during surgery. Results. Twenty-five procedures were performed in 18 consecutive patients. In 24% of all surgeries, resection was stopped because a functional area or cortical tract was identified in the resection area or because motor evoked potential amplitudes were reduced in an area where fluorescent tumor cells were still seen intraoperatively. Gross-total resection could be achieved in 16 (64%) of the surgeries with preservation of all functional areas and fiber tracts. In 2 patients presurgical hemiparesis became accentuated postoperatively, and 1 of these patients also suffered from a new homonymous hemianopia following a second resection. Conclusions. The authors' first results show that tumor resections with 5-ALA in combination with intraoperative cortical stimulation have the advantages of both methods and, thus, provide additional safety for the neurosurgeon during resections of primary malignant brain tumors in eloquent areas. Nonetheless, more cases and additional studies are necessary to further prove the advantages of this multimodal strategy.

Objective: Hemifacial spasm (HFS) is thought to be due to facial motor nucleus hyperactivity related to chronic neurovascular contact. Microvascular decompression (MVD) is the only definite treatment rendering high rates of cure. Intraoperative monitoring has been advocated during such procedures by[for full text, please go to the a.m. URL], 61. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC) im Rahmen der Neurowoche 2010

Objective: Surgery of large arteriovenous malformations represents one of the most challenging tasks confronting neurosurgeons. Especially those situated in motor areas are difficult to treat due to the risk of producing severe functional impairment. Surgical indication for patients harboring AVMs in[for full text, please go to the a.m. URL], 61. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC) im Rahmen der Neurowoche 2010

A formal validation study was performed, in order to investigate whether the commercially available reconstructed human epidermis (RHE) models, EPISKIN (R), EpiDerm (TM) and SkinEthic (R), are suitable for in vitro skin absorption testing. The skin types currently recommended in the OECD Test Guideline 4 28, namely, ex vivo human epidermis and pig skin, were used as references. Based on the promising outcome of the prevalidation study, the panel of test substances was enlarged to nine substances, covering a wider spectrum of physicochemical properties. The substances were tested under both infinite-dose and finite-dose conditions, in ten laboratories, under strictly controlled conditions. The data were subjected to independent statistical analyses. Intra-laboratory and inter-laboratory variability contributed almost equally to the total variability, which was in the same range as that in preceding studies. In general, permeation of the RHE models exceeded that of human epidermis and pig skin (the SkinEthic RHE was found to be the most permeable), yet the ranking of substance permeation through the three tested RHE models and the pig skin reflected the permeation through human epidermis. in addition, both infinite-dose and finite-dose experiments are feasible with RHE models. The RHE models did not show the expected significantly better reproducibility, as compared to excised skin, despite a tendency toward lower variability of the data. Importantly, however, the permeation data showed a sufficient correlation between all the preparations examined. Thus, the RHE models, EPISKIN, EpiDerm and SkinEthic, are appropriate alternatives to human and pig skin, for the in vitro assessment of the permeation and penetration of substances when applied as aqueous solutions.

Regulatory requirements: According to the current Notes for Guidance of the Scientific Committee on Cosmetic Products and Non-Food Products (SCCNFP), cosmetic ingredients and mixtures of ingredients absorbing UV light (in particular UV filter chemicals used, for example, to ensure the light stability of cosmetics or used in sun protection products) should be tested for acute phototoxic and photogenotoxic potential. Testing for photosensitisation (immunological photoallergy) potential is not specifically required, but it is nevertheless often performed. Acute phototoxicity: Due to a thorough multi-stage and multi-centre validation trial (1992-1998) the In Vitro 3T3 Neutral Red Uptake Phototoxicity Test (3T3-NRU-PT) had already gained acceptance by the SCCNFP in 1998, and it is recommended by the EMEA/CPMP as a basic preclinical test for acute phototoxicity. It was accepted as Method No. 41 in Annex V to Directive 67/548/EEC in the year 2000, and was accepted as the new Test Guideline 432 by the OECD in 2002. The 3T3-NRU-PT is regarded as a basic screen for identifying acute phototoxic potential. Two additional in vitro tests, formally evaluated in controlled blind trials, the RBC Phototoxicity Test (RBC-PT) and the Human 3-D Skin Model Phototoxicity Test (H3D-PT), are regarded as useful and important adjunct tests to overcome some limitations of the 3T3-NRU-PT, namely the fairly low UVB tolerance of the 3T3 fibroblasts and the inability to model the bioavailability of test materials topically applied to the skin. In addition, the RBC-PT permits an evaluation of the phototoxic mechanisms involved. In conclusion, the identification of acute phototoxic hazards is now regarded as being sufficiently covered by in vitro tests, so that animal testing for that endpoint can now be 100% replaced. Photogenotoxicity: In the area of photogenotoxicity, almost the whole battery of in vitro genetic toxicity tests have been (or are currently being) converted into test protocols of photogenotoxicity tests. Tests exclusively predictive for gene mutation, for example, the Photo-Ames (P-Ames) Test and the Photo-Thymidine Kinase Test (P-TKT), have become less important than tests for clastogenic effects (for example, the Photo-Chromosome Aberration Test [P-CAT] and the Photo-Micronucleus Test [P-MNT]). In addition, a number of promising indicator tests, such as the Photo-Comet Assay (P-Comet) have been developed. Although routinely used, to date none of the new photogenotoxicity tests have been formally validated. Therefore, the P-MNT and the P-Comet are currently being evaluated in a formal interlaboratory validation study. It is expected that these in vitro photogenotoxicity test methods may become available as validated and accepted methods within the next five years. Photoallergy (Photosensitisation): In the area of photoallergy (photosensitisation), as development of predictive in vitro tests for delayed contact sensitisation (allergenicity) potential without the involvement of light, due to a lack of ability to model the complex mechanisms underlying allergy, no promising in vitro methods to predict photo-sensitisation potential are currently in sight (see the section on skin sensitisation). One in vitro screening method, which models the covalent binding of a light activated chemical to human serum albumin, may become relevant. However, while the binding of an excited chemical to proteins is a prerequisite for photoallergy, this is not a sufficient predictor on its own. The only promising alternatives currently under development are in vivo refinements, like the Photo Local Lymph Node Assay (PLLNA). Once a reliable and predictive in vitro test battery and strategy for the assessment of "dark" sensitisation potential have been developed and accepted, their adaptation into similar photosensitisation testing will become possible.