Feasibility of 3 Tesla MRI for the assessment of mid-palatal suture maturation: a retrospective pilot study

The maxilla occupies a key position in dentofacial orthopaedics, since its transversal development can be directly influenced by orthodontic therapy. The maturation stages of the mid-palatal suture, which are obtained from cone-beam computed tomography images (CBCT), present an addition to clinical decision-making in transversal discrepancies of the upper jaw. In an endeavour to reduce ionizing radiation in adolescents and young adults, who are particularly susceptible to long term stochastic irradiation effects, we investigated the feasibility of 3 Tesla (3T) MRI in detecting the maturation stages of the mid-palatal suture. A collective of 30 patients aged 24-93 years with routine neck MRI at 3T, underwent an additional three-dimensional isotropic T1 weighted study sequence of the midface. Image evaluation was performed on axial, multi-planar formatted reconstructions of the dataset aligned to the midline axis of the palate, and curved reconstructions aligned to the concavity of the palate. Inverted images helped to achieve an image impression similar to the well-known CBCT appearance. All datasets were reviewed by three readers and mid-palatal maturation was scored twice according to Angelieri et al. Intra- and inter-rater agreement were evaluated to measure the robustness of the images for clinical evaluation. 3T MRI deemed reliable for the assessment of mid-palatal suture maturation and hence for the appraisal of the hard palate and its adjacent sutures. The data of this pilot study display the feasibility of non-ionizing cross-sectional MRI for the determination of sutural maturation stages. These findings underline the potential of MRI for orthodontic treatment planning, further contributing to the avoidance of unnecessary radiation doses.

Investigation of the Impact of Temporal Dose Delivery Patterns of Ion Irradiation with the Local Effect Model

We present an extension of the Local Effect Model (LEM) to include time-dose relationships for predicting effects of protracted and split-dose ion irradiation at arbitrary LET. With this kinetic extension, the spatial and temporal induction and processing of DNA double strand breaks (DSB) in cellular nuclei can be simulated for a wide range of ion radiation qualities, doses and dose rates. The key concept of the extension is based on the joint spatial and temporal coexistence of initial DSB, leading to the formation of clustered DNA damage on the µm scale (as defined e.g., by the size scale of Mbp chromatin loops), which is considered to have an increased cellular lethality as compared to isolated, single DSB. By simulating the time dependent induction and repair of DSB and scoring of isolated and clustered DSB upon irradiation, the impact of dose rate and split dose on the cell survival probability can be computed. In a first part of this work, we systematically analyze the predicted impact of protraction in dependence of factors like dose, LET, ion species and radiosensitivity as characterized by the photon LQ-parameters. We establish links to common concepts that describe dose rate effects for low LET radiation. We also compare the model predictions to experimental data and find agreement with the general trends observed in the experiments. The relevant concepts of our approach are compared to other models suitable for predicting time effects. We investigate an apparent analogy between spatial and temporal concentration of radiation delivery, both leading to increased effectiveness, and discuss similarities and differences between the general dependencies of these clustering effects on their impacting factors. Finally, we conclude that the findings give additional support for the general concept of the LEM, i.e. the characterization of high LET radiation effects based on the distinction of just two classes of DSB (isolated DSB and clustered DSB).

Relative biological effectiveness of oxygen ion beams in the rat spinal cord: Dependence on linear energy transfer and dose and comparison with model predictions

Background and purpose

Ion beams exhibit an increased relative biological effectiveness (RBE) with respect to photons. This study determined the RBE of oxygen ion beams as a function of linear energy transfer (LET) and dose in the rat spinal cord.

Materials and methods

The spinal cord of rats was irradiated at four different positions of a 6 cm spread-out Bragg-peak (LET: 26, 66, 98 and 141 keV/µm) using increasing levels of single and split oxygen ion doses. Dose-response curves were established for the endpoint paresis grade II and based on ED50 (dose at 50 % effect probability), the RBE was determined and compared to model predictions.

Results

When LET increased from 26 to 98 keV/µm, ED50 decreased from 17.2 ± 0.3 Gy to 13.5 ± 0.4 Gy for single and from 21.7 ± 0.4 Gy to 15.5 ± 0.5 Gy for split doses, however, at 141 keV/µm, ED50 rose again to 15.8 ± 0.4 Gy and 17.2 ± 0.4 Gy, respectively. As a result, the RBE increased from 1.43 ± 0.05 to 1.82 ± 0.08 (single dose) and from 1.58 ± 0.04 to 2.21 ± 0.08 (split dose), respectively, before declining again to 1.56 ± 0.06 for single and 1.99 ± 0.06 for split doses at the highest LET. Deviations from RBE-predictions were model-dependent.

Conclusion

This study established first RBE data for the late reacting central nervous system after single and split doses of oxygen ions. The data was used to validate the RBE-dependence on LET and dose of three RBE-models. This study extends the existing data base for protons, helium and carbon ions and provides important information for future patient treatments with oxygen ions.

Newborn screening in metachromatic leukodystrophy - European consensus-based recommendations on clinical management

INTRODUCTION

Metachromatic leukodystrophy (MLD) is a rare autosomal recessive lysosomal storage disorder resulting from arylsulfatase A enzyme deficiency, leading to toxic sulfatide accumulation. As a result affected individuals exhibit progressive neurodegeneration. Treatments such as hematopoietic stem cell transplantation (HSCT) and gene therapy are effective when administered pre-symptomatically. Newborn screening (NBS) for MLD has recently been shown to be technically feasible and is indicated because of available treatment options. However, there is a lack of guidance on how to monitor and manage identified cases. This study aims to establish consensus among international experts in MLD and patient advocates on clinical management for NBS-identified MLD cases.

METHODS

A real-time Delphi procedure using eDELPHI software with 22 experts in MLD was performed. Questions, based on a literature review and workshops, were answered during a seven-week period. Three levels of consensus were defined: A) 100%, B) 75-99%, and C) 50-74% or >75% but >25% neutral votes. Recommendations were categorized by agreement level, from strongly recommended to suggested. Patient advocates participated in discussions and were involved in the final consensus.

RESULTS

The study presents 57 statements guiding clinical management of NBS-identified MLD patients. Key recommendations include timely communication by MLD experts with identified families, treating early-onset MLD with gene therapy and late-onset MLD with HSCT, as well as pre-treatment monitoring schemes. Specific knowledge gaps were identified, urging prioritized research for future evidence-based guidelines.

DISCUSSION

Consensus-based recommendations for NBS in MLD will enhance harmonized management and facilitate integration in national screening programs. Structured data collection and monitoring of screening programs are crucial for evidence generation and future guideline development. Involving patient representatives in the development of recommendations seems essential for NBS programs.

Enhanced RBE of Particle Radiation Depends on Beam Size in the Micrometer Range

High-linear energy transfer (LET) radiation, such as heavy ions is associated with a higher relative biological effectiveness (RBE) than low-LET radiation, such as photons. Irradiation with low- and high-LET particles differ in the interaction with the cellular matter and therefore in the spatial dose distribution. When a single high-LET particle interacts with matter, it results in doses of up to thousands of gray (Gy) locally concentrated around the ion trajectory, whereas the mean dose averaged over the target, such as a cell nucleus is only in the range of a Gy. DNA damage therefore accumulates in this small volume. In contrast, up to hundreds of low-LET particle hits are required to achieve the same mean dose, resulting in a quasi-homogeneous damage distribution throughout the cell nucleus. In this study, we investigated the dependence of RBE from different spatial dose depositions using different focused beam spot sizes of proton radiation with respect to the induction of chromosome aberrations and clonogenic cell survival. Human-hamster hybrid (AL) as well as Chinese hamster ovary cells (CHO-K1) were irradiated with focused low LET protons of 20 MeV (LET = 2.6 keV/µm) beam energy with a mean dose of 1.7 Gy in a quadratic matrix pattern with point spacing of 5.4 × 5.4 µm2 and 117 protons per matrix point at the ion microbeam SNAKE using different beam spot sizes between 0.8 µm and 2.8 µm (full width at half maximum). The dose-response curves of X-ray reference radiation were used to determine the RBE after a 1.7 Gy dose of radiation. The RBE for the induction of dicentric chromosomes and cell inactivation was increased after irradiation with the smallest beam spot diameter (0.8 µm for chromosome aberration experiments and 1.0 µm for cell survival experiments) compared to homogeneous proton radiation but was still below the RBE of a corresponding high LET single ion hit. By increasing the spot size to 1.6-1.8 µm, the RBE decreased but was still higher than for homogeneously distributed protons. By further increasing the spot size to 2.7-2.8 µm, the RBE was no longer different from the homogeneous radiation. Our experiments demonstrate that varying spot size of low-LET radiation gradually modifies the RBE. This underlines that a substantial fraction of enhanced RBE originates from inhomogeneous energy concentrations on the µm scale (mean intertrack distances of low-LET particles below 0.1 µm) and quantifies the link between such energy concentration and RBE. The missing fraction of RBE enhancement when comparing with high-LET ions is attributed to the high inner track energy deposition on the nanometer scale. The results are compared with model results of PARTRAC and LEM for chromosomal aberration and cell survival, respectively, which suggest mechanistic interpretations of the observed radiation effects.

Internal vascular anatomy of the human lacrimal gland: A protocol based on cadaver dissection and three-dimensional micro-computed tomography

PURPOSE

To evaluate the feasibility of studying the vascular supply of the orbital and palpebral lobes of the human lacrimal gland using micro-computed tomography (micro-CT) and microscopic dissection.

METHODS

The lacrimal gland artery of a fresh parasagittalized cadaver head (male, aged 76 years) was infused with a lead oxide-latex mixture near the occipital pole of the gland. The entire lacrimal gland was imaged using micro-CT and 3D cinematic rendering (CR) and then dissected under a surgical microscope.

RESULTS

Micro-CT and CR images showed well-demarcated internal vascular branches of the lacrimal artery and their distribution within the orbital and palpebral lobes. The entire course of the artery and its branches could be visualized by CR and microscopic dissection, with the former showing better spatial orientation and finer branching. The main artery runs along the free edge of the aponeurosis of the levator palpebrae superior muscle and lies in the isthmus portion of the gland (between the orbital and palpebral lobes). The branches of the main lacrimal artery include one branch to the orbital adipose tissue just before entering the gland, two branches to the orbital lobe (medial and lateral), and two branches to the palpebral lobe (medial and lateral). The main artery terminates as palpebral and orbital lobe branches in the lateral half of the lacrimal gland.

CONCLUSION

Latex and contrast-enhanced micro-CT is very well suited to visualize the vascular anatomy of the lacrimal artery within the gland. A large number of lacrimal gland examinations using the method presented here are required to demonstrate and understand the variability of the vascular anatomy of the human lacrimal gland.

Spectral composition of secondary electrons based on the Kiefer-Straaten ion track structure model

The major part of energy deposition of ionizing radiation is caused by secondary electrons, independent of the primary radiation type. However, their spatial concentration and their spectral properties strongly depend on the primary radiation type and finally determine the pattern of molecular damage e.g. to biological targets as the DNA, and thus the final effect of the radiation exposure. To describe the physical and to predict the biological consequences of charged ion irradiation, amorphous track structure approaches have proven to be pragmatic and helpful. There, the local dose deposition in the ion track is equated by considering the emission and slowing down of the secondary electrons from the primary particle track. In the present work we exploit the model of Kiefer and Straaten and derive the spectral composition of secondary electrons as function of the distance to the track center. The spectral composition indicates differences to spectra of low linear energy transfer (LET) photon radiation, which we confirm by a comparison with Monte Carlo studies. We demonstrate that the amorphous track structure approach provides a simple tool for evaluating the spectral electron properties within the track structure. Predictions of the LET of electrons across the track structure as well as the electronic dose build-up effect are derived. Implications for biological effects and corresponding predicting models based on amorphous track structure are discussed.

Carbon Ion and Photon Radiation Therapy Show Enhanced Antitumoral Therapeutic Efficacy With Neoantigen RNA-LPX Vaccines in Preclinical Colon Carcinoma Models

PURPOSE

Personalized liposome-formulated mRNA vaccines (RNA-LPX) are a powerful new tool in cancer immunotherapy. In preclinical tumor models, RNA-LPX vaccines are known to achieve potent results when combined with conventional X-ray radiation therapy (XRT). Densely ionizing radiation used in carbon ion radiation therapy (CIRT) may induce distinct effects in combination with immunotherapy compared with sparsely ionizing X-rays.

METHODS AND MATERIALS

Within this study, we investigate the potential of CIRT and isoeffective doses of XRT to mediate tumor growth inhibition and survival in murine colon adenocarcinoma models in conjunction with neoantigen (neoAg)-specific RNA-LPX vaccines encoding both major histocompatibility complex (MHC) class I- and class II-restricted tumor-specific neoantigens. We characterize tumor immune infiltrates and antigen-specific T cell responses by flow cytometry and interferon-γ enzyme-linked immunosorbent spot (ELISpot) analyses, respectively.

RESULTS

NeoAg RNA-LPX vaccines significantly potentiate radiation therapy-mediated tumor growth inhibition. CIRT and XRT alone marginally prime neoAg-specific T cell responses detected in the tumors but not in the blood or spleens of mice. Infiltration and cytotoxicity of neoAg-specific T cells is strongly driven by RNA-LPX vaccines and is accompanied by reduced expression of the inhibitory markers PD-1 and Tim-3 on these cells. The neoAg RNA-LPX vaccine shows similar overall therapeutic efficacy in combination with both CIRT and XRT, even if the physical radiation dose is lower for carbon ions than for X-rays.

CONCLUSIONS

We hence conclude that the combination of CIRT and neoAg RNA-LPX vaccines is a promising strategy for the treatment of radioresistant tumors.

Vulnerable in the end - Longitudinal study among medical students on mental health and personal and work-related resources over a 5.5-year-period

BACKGROUND

Mental health problems are common in medical professionals and their development already starts at the undergraduate level. Studies on medical students can replicate higher prevalence for depression and burnout in this group, but they normally compare semester cohorts in an anonymized, cross-sectional approach and without a preventive perspective.

METHODS

We surveyed medical students at the beginning and end of their medical curriculum and collected data on burnout, depressivity, work related experience and salutogenesis parameters with validated self-administered questionnaires. Most remarkably we obtained the data from the same 58 individuals after 5.5 years, representing data of the highest quality in order to compare the mental health status at the beginning and the end of our students´ medical curriculum.

RESULTS

Our results not only show a severe exacerbation of physical, mental and emotional burnout in the participants at the end of their studies. The students also do not seem to have sufficient personal (resilience) or social resources (e.g. experience of social support) for coping with their mental health problems around the time of their graduation.

CONCLUSIONS

Our participants reflect a development of mental health during their medical studies at university that is paving the way to the devastating prevalence of mental disorders and suicide in health professionals. From our results we derive an urgent need to integrate self-care and active coping in the learning goals of medical curricula.

New insights into lacrimal gland anatomy using 7T MRI and electron microscopy: Relevance for lacrimal gland targeted therapies and bioengineering

PURPOSE

To study the tissue architecture, isthmus (connection between two lobes) of the lacrimal gland using preclinical 7T MRI in combination with histology and electron microscopy.

METHODS

Ten lacrimal glands from Caucasian body donors (mean age 78.7 years) were studied using 7T-MRI (N = 5; scanned at 75-μm intervals), histology, and electron microscopy (N = 5) and 3D cinematic rendering (CR) techniques.

RESULTS

3D CR images showed uniform-sized lobules (widest lobule diameter, 1.68 ± 0.19 mm in orbital lobe, 1.68 ± 0.17 mm in palpebral lobe) in both lobes, separated by septae (size, 0.29 ± 0.09 mm). The internal framework of the gland resembled a honeycoomb pattern. In CR and histology, the isthmus contained glandular acini, large blood vessels, nerves, and no more than two ducts having a tortuous course towards the conjunctival surface. On assigning a color display to the rendered lacrimal gland, all glands showed a blood vessel originating from the main lacrimal artery just 5 mm beyond the hilum and making it course to the palpebral lobe via isthmus. The distance between the conjunctiva and the central substance of the orbital and palpebral lobe was 9.4 ± 0.2 mm and 2.8 ± 0.7 mm, respectively. Electron microscopy of the palpebral lobe revealed compact subepithelial layer in the overlying conjunctiva, followed by loosely scattered collagen bundles that contained the gland lobules.

CONCLUSION

3D-CR can be used to study the lacrimal gland microstructure, help fabricate a 3D scaffold for lacrimal gland bioprinting, and serve as guide for transconjunctival lacrimal gland targeted therapies i.e., 2.9 & 9 mm long needle to reach the orbital and palpebral lobe center, respectively in normal-size glands.

Circular dichroism in hard X-ray photoelectron diffraction observed by time-of-flight momentum microscopy

X-ray photoelectron diffraction (XPD) is a powerful technique that yields detailed structural information of solids and thin films that complements electronic structure measurements. Among the strongholds of XPD we can identify dopant sites, track structural phase transitions, and perform holographic reconstruction. High-resolution imaging of k_ll-distributions (momentum microscopy) presents a new approach to core-level photoemission. It yields full-field k_x-k_y XPD patterns with unprecedented acquisition speed and richness in details. Here, we show that beyond the pure diffraction information, XPD patterns exhibit pronounced circular dichroism in the angular distribution (CDAD) with asymmetries up to 80%, alongside with rapid variations on a small k_ll-scale (0.1 Å^-1). Measurements with circularly-polarized hard X-rays (hν = 6 keV) for a number of core levels, including Si, Ge, Mo and W, prove that core-level CDAD is a general phenomenon that is independent of atomic number. The fine structure in CDAD is more pronounced compared to the corresponding intensity patterns. Additionally, they obey the same symmetry rules as found for atomic and molecular species, and valence bands. The CD is antisymmetric with respect to the mirror planes of the crystal, whose signatures are sharp zero lines. Calculations using both the Bloch-wave approach and one-step photoemission reveal the origin of the fine structure that represents the signature of Kikuchi diffraction. To disentangle the roles of photoexcitation and diffraction, XPD has been implemented into the Munich SPRKKR package to unify the one-step model of photoemission and multiple scattering theory.

Cinematic rendering to improve visualization of supplementary and ectopic teeth using CT datasets

OBJECTIVES

Ectopic, impacted, and supplementary teeth are the number one reason for cross-sectional imaging in pediatric dentistry. The accurate post-processing of acquired data sets is crucial to obtain precise, yet also intuitively understandable three-dimensional (3D) models, which facilitate clinical decision-making and improve treatment outcomes. Cinematic rendering (CR) is anovel visualization technique using physically based volume rendering to create photorealistic images from DICOM data. The aim of the present study was to tailor pre-existing CR reconstruction parameters for use in dental imaging with the example of the diagnostic 3D visualization of ectopic, impacted, and supplementary teeth.

METHODS

CR was employed for the volumetric image visualization of midface CT data sets. Predefined reconstruction parameters were specifically modified to visualize the presented dental pathologies, dentulous jaw, and isolated teeth. The 3D spatial relationship of the teeth, as well as their structural relationship with the antagonizing dentition, could immediately be investigated and highlighted by separate, interactive 3D visualization after segmentation through windowing.

RESULTS

To the best of our knowledge, CR has not been implemented for the visualization of supplementary and ectopic teeth segmented from the surrounding bone because the software has not yet provided appropriate customized reconstruction parameters for dental imaging. When employing our new, modified reconstruction parameters, its application presents a fast approach to obtain realistic visualizations of both dental and osseous structures.

CONCLUSIONS

CR enables dentists and oral surgeons to gain an improved 3D understanding of anatomical structures, allowing for more intuitive treatment planning and patient communication.

Leptin mediates protective effects on the vasculature

Introduction and purpose

Lipodystrophy (LD) syndromes are characterized by the loss of adipose tissue resulting in metabolic complications and accelerated atherosclerosis. The systemic concentration of the adipokine leptin is reduced in LD as a result of adipose tissue deficiency. A therapeutical option to treat LD is the substitution of leptin, which improves metabolic complications and reduces mortality. However, the vascular effects of leptin remain largely unknown.

Here we analyze the direct effects of leptin on the vascular system and the development of atherosclerosis.

Methods and results

Treatment of human endothelial cells (ECs) with leptin reduced endothelial inflammation and the process of endothelial-to-mesenchymal transition (EndMT) (CNN1, −41.4%, p<0.05, n=4). In addition, leptin administration prevented the EndMT-induced increase of endothelial permeability. The protective effect of leptin on EndMT was confirmed in vivo in a combined lipodystrophic and atherosclerosis-prone mouse model (LDLR−/−; aP2-nSrebp1c). Treatment of the mice with leptin (3.0 mg/kg body weight daily for 8 weeks) decreased EndMT. Leptin showed no effect on plaques size but reduced the protrusion of plaques in atherosclerotic areas of the aortic roots (−31%, p<0.05, n=4–6).

Cytokine screening revealed an increase of the growth differentiation factor 15 (GDF15) in serum of LD patients (+26.2%, p<0.05, n=53–58) and in ECs after EndMT (+138%, p<0.05, n=6743–10920). This increase was reversed using leptin treatment in ECs undergoing EndMT, in the LD mice model, and in LD patients after 4 weeks of leptin administration. Indeed, treatment of endothelial cells with GDF15 induced EndMT (CNN1, +7.7-fold-control, p<0.05, n=3), and impaired EC barrier function. Neutralizing antibodies targeting GDF15 inhibited EndMT-mediated expression of mesenchymal genes (CNN1, −54%, p<0.05, n=4). The treatment of ECs with serum from LD patients induced EndMT and the increase of mesenchymal marker expression was inhibited with additional administration with neutralizing antibodies targeting GDF15 (CNN1, −28%, p<0.05, n=3).

Conclusion

Our findings indicate that EndMT is part of the cardiovascular disease progression in lipodystrophy syndromes. Leptin treatment has direct protective vascular effects by preventing inflammation, EndMT, and maintaining endothelial integrity.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)

A-206 Memory Complaints in Older Adults: Relationships Between Self and Informant Report, Objective Test Performance and Symptoms of Depression

Objective: We explored the relationships between objective memory performance, self and informant reports of problems in daily life, and depression in elderly patients with dementia, mild cognitive impairment (MCI), or subjective memory complaints (SMC).

Method: We used archival data from 100 individuals referred for outpatient neuropsychological evaluation because of memory concerns. The sample was largely White (97%), female (53%), with typical educational attainment (M= 13.25). CVLT–II Total scores characterized memory performance. BRIEF—A Metacognitive Index (MI) scores characterized examinee and informant perspectives on problems in daily life, allowing calculation of a discrepancy score between raters. PHQ—9 scores (raw) characterized depression symptom severity. Patient groups included dementia (n = 31), MCI (n = 34), and SMC (n= 35). Chi-square and ANOVA tests were the primary analyses of group relationships.

Results: There was a significant difference between the dementia and SMC groups on the BRIEF–A (p < .01). Informants reported greater problems than patients in the dementia group, whereas this pattern was reversed in the SMC group. Ratings in the MCI group were minimally discrepant. Elevated depression correlated with greater self-reported cognitive dysfunction (p < .002), with depression most prominent in the SMC group. Across the sample, only informant’s report of greater problems in daily life was associated with worse CVLT–II performance (p < .001).

Conclusions: We conclude that adding standardized rating scales alongside objective memory testing is informative in evaluations of memory loss concerns. Beyond collecting both patient and informant ratings of daily functioning, screening for depression is also necessary to put self-reported difficulties into context.

Modeling secondary cancer risk ratios for proton versus carbon ion beam therapy: A comparative study based on the local effect model

BACKGROUND

Ion beam therapy allows for substantial sparing of normal tissues. Besides deterministic normal-tissue complications, stochastic long-term effects like secondary cancer (SC) induction are of importance when comparing different treatment modalities.

PURPOSE

To develop a modeling approach for comparison of SC risk in proton and carbon ion therapy.

METHODS AND MATERIALS

The local effect model (LEM) is used to predict the relative biological effectiveness (RBE) of SC induction after particle therapy. A key feature of the new approach is the double use of the LEM, reflecting the competition between the two processes of mutation induction (leading to cancer development) and cell inactivation (leading to suppression of cancer development). Based on previous investigations, treatment plans were in this work analyzed for an idealized geometry in order to assess the underlying systematic dependencies of cancer induction. In a further step, relative SC risks were predicted for proton and carbon ion treatment plans prepared for 10 prostate cancer patients.

RESULTS

We investigated the impact of factors such as treatment plan geometry, fractionation scheme, and tissue radiosensitivity to photon irradiation on the ion beam SC risk. Our model studies do not result in a clear preference for either protons or carbon ions, but rather indicate a complex interplay of different aspects. Reduced lateral scattering leads to a lower SC risk for carbon ions compared to protons at the lateral field margins in the entrance channel, while an increased risk was found closely behind the tumor due to projectile fragmentation. The fractionation scheme had little impact on the expected risk ratio. With respect to sensitivity parameters, those characterizing RBE for cell killing of potentially cancerous cells as well as of the primary tumor had the most significant impact. The observed general systematic dependencies are in agreement with results from previous model studies. The prostate patient study reveals reduced SC risks predictions for skin and bones for carbon ions as compared to protons, but higher mean risks for bladder and rectum.

CONCLUSION

The methods established in this work provide a basis for further investigating treatment optimizing strategies for ion beam therapy with regard to SC risk comparisons.

A double-strand-break model for the relative biological effectiveness of electrons based on ionization clustering

BACKGROUND

The effectiveness of ionizing radiation regarding DNA damage induction depends on its spatial energy deposition pattern. For electrons an increased effectiveness is observed at low kinetic energies due to the enhanced density of energy deposition events at electron track ends.

PURPOSE

A model is presented, which enables the calculation of the double-strand-break (DSB) yield and the relative biological effectiveness (RBE) for DSB induction of electrons.

METHODS

The model applies the mean free path between two ionizations and the assumption that two ionizations within a certain threshold distance are necessary to potentially lead to a DSB. Next to an expression for the electron RBE according to its common definition, a local RBE is determined, which describes the electrons' local effectiveness at a defined point on their track.

RESULTS

This local RBE allows a better understanding of microscopic processes resulting from radiation and can be used, for instance, to describe the mean effectiveness of the mixed electron radiation field as a function of the radial distance to the center of an ion track.

CONCLUSIONS

The presented model reflects the experimentally observed increased effectiveness of low-energetic electrons. It will be used in a future work to improve RBE predictions for ions performed with the local effect model.

The comparison of the morphology of the mid-palatal suture between edentulous individuals and dentate jaws shows morphological differences

BACKGROUND

A profound understanding of the evolution and anatomy of the viscero- and neurocranium is quintessentially important for orthodontists. This particularly alludes to structures, which are directly targeted by orthodontic therapy such as the maxilla and the mid-palatal suture. The anatomy of the mid-palatal suture of toothed individuals is well described, whereas little is known about sutures' morphological changes after tooth loss. Therefore, the aim of this study was to evaluate the edentulous mid-palatal suture by means of histologic and histomorphometric analysis.

METHODS

Ten mid-palatal sutures of edentulous donors as well as six age- and sex matched dentulous controls were examined. For the histological and histomorphometric analysis (sutural width, obliteration, vascularization and interdigitation) conventional staining protocols (HE, Movat-Pentachrome, Sirius Red) and immunofluorescence (vWF, TRAP) were performed. Histomorphometric analysis was carried out using NIS-elements imaging software.

RESULTS

When compared to dentulous controls, the edentulous investigation group showed a decreased vascularization and sutural width as well as an increased sutural obliteration. Notably, a high variability and inhomogeneity within regard the histomorphometric parameters was seen in edentulous samples.

CONCLUSIONS

The mid-palatal suture of edentulous individuals showed significant morphological differences compared to individuals with toothed jaws. The loss of teeth and thereby functional loading seems to have a considerable impact on sutures' morphology.

Performance of a cryo-cooled crystal monochromator illuminated by hard X-rays with MHz repetition rate at the European X-ray Free-Electron Laser

Due to the high intensity and MHz repetition rate of photon pulses generated by the European X-ray Free-Electron Laser, the heat load on silicon crystal monochromators can become large and prevent ideal transmission in Bragg diffraction geometry due to crystal deformation. Here, we present experimental data illustrating how heat load affects the performance of a cryogenically cooled monochromator under such conditions. The measurements are in good agreement with a depth-uniform model of X-ray dynamical diffraction taking beam absorption and heat deformation of the crystals into account.

Comprehensive comparison of local effect model IV predictions with the particle irradiation data ensemble

PURPOSE

The increased relative biological effectiveness (RBE) of ions is one of the key benefits of ion radiotherapy compared to conventional radiotherapy with photons. To account for the increased RBE of ions during the process of ion radiotherapy treatment planning, a robust model for RBE predictions is indispensable. Currently, at several ion therapy centers the local effect model I (LEM I) is applied to predict the RBE, which varies with biological and physical impacting factors. After the introduction of LEM I, several model improvements were implemented, leading to the current version, LEM IV, which is systematically tested in this study.

METHODS

As a comprehensive RBE model should give consistent results for a large variety of ion species and energies, the particle irradiation data ensemble (PIDE) is used to systematically validate the LEM IV. The database covers over 1100 photon and ion survival experiments in form of their linear-quadratic parameters for a wide range of ion types and energies. This makes the database an optimal tool to challenge the systematic dependencies of the RBE model. After appropriate filtering of the database, 571 experiments were identified and used as test data.

RESULTS

The study confirms that the LEM IV reflects the RBE systematics observed in measurements well. It is able to reproduce the dependence of RBE on the linear energy transfer (LET) as well as on the α_γ /β_γ ratio for several ion species in a wide energy range. Additionally, the systematic quantitative analysis revealed precision capabilities and limits of the model. At lower LET values, the LEM IV tends to underestimate the RBE with an increasing underestimation with increasing atomic number of the ion. At higher LET values, the LEM IV overestimates the RBE for protons or helium ions, whereas the predictions for heavier ions match experimental data well.

CONCLUSIONS

The LEM IV is able to predict general RBE characteristics for several ion species in a broad energy range. The accuracy of the predictions is reasonable considering the small number of input parameters needed by the model. The detailed quantification of possible systematic deviations, however, enables to identify not only strengths but also limitations of the model. The gained knowledge can be used to develop model adjustments to further improve the model accuracy, which is on the way.

Biological Impact of Target Fragments on Proton Treatment Plans: An Analysis Based on the Current Cross-Section Data and a Full Mixed Field Approach

Simple Summary

Proton therapy is now an established external radiotherapy modality for cancer treatment. Clinical routine currently neglects the radiobiological impact of nuclear target fragments even if experimental evidences show a significant enhancement in cell-killing effect due to secondary particles. This paper quantifies the contribution of proton target fragments of different charge in different irradiation scenarios and compares the computationally predicted corrections to the overall biological dose with experimental data.

Abstract

Clinical routine in proton therapy currently neglects the radiobiological impact of nuclear target fragments generated by proton beams. This is partially due to the difficult characterization of the irradiation field. The detection of low energetic fragments, secondary protons and fragments, is in fact challenging due to their very short range. However, considering their low residual energy and therefore high LET, the possible contribution of such heavy particles to the overall biological effect could be not negligible. In this context, we performed a systematic analysis aimed at an explicit assessment of the RBE (relative biological effectiveness, i.e., the ratio of photon to proton physical dose needed to achieve the same biological effect) contribution of target fragments in the biological dose calculations of proton fields. The TOPAS Monte Carlo code has been used to characterize the radiation field, i.e., for the scoring of primary protons and fragments in an exemplary water target. TRiP98, in combination with LEM IV RBE tables, was then employed to evaluate the RBE with a mixed field approach accounting for fragments’ contributions. The results were compared with that obtained by considering only primary protons for the pristine beam and spread out Bragg peak (SOBP) irradiations, in order to estimate the relative weight of target fragments to the overall RBE. A sensitivity analysis of the secondary particles production cross-sections to the biological dose has been also carried out in this study. Finally, our modeling approach was applied to the analysis of a selection of cell survival and RBE data extracted from published in vitro studies. Our results indicate that, for high energy proton beams, the main contribution to the biological effect due to the secondary particles can be attributed to secondary protons, while the contribution of heavier fragments is mainly due to helium. The impact of target fragments on the biological dose is maximized in the entrance channels and for small α/β values. When applied to the description of survival data, model predictions including all fragments allowed better agreement to experimental data at high energies, while a minor effect was observed in the peak region. An improved description was also obtained when including the fragments’ contribution to describe RBE data. Overall, this analysis indicates that a minor contribution can be expected to the overall RBE resulting from target fragments. However, considering the fragmentation effects can improve the agreement with experimental data for high energy proton beams.

The attitudes of European medical students towards the clinical importance of neuroanatomy

The attitudes of medical students towards the clinical importance of neuroanatomy have been little studied. Because it has been reported that medical students find neuroanatomy difficult and can have 'neurophobia', here we test the hypothesis that early-stage medical students across Europe have a low regard for neuroanatomy's clinical relevance. The work was conducted under the auspices of the Trans-European Pedagogic Research Group (TEPARG), with just over 1500 students from 12 European medical schools providing responses to a survey (52% response rate) that assessed their attitudes using Thurstone and Chave methodologies. Regardless of the university surveyed, and of the teaching methods employed for neuroanatomy, our findings were not consistent with our hypothesis. However, the students had a less favourable opinion of neuroanatomy's importance compared to gross anatomy; although their attitudes were more positive than previously reported for histology and embryology. The extent to which neuroanatomy plays a significant role in the early years of medical education is moot. Nevertheless, we conclude that in addition to newly recruited medical students being informed of the subject's role in a healthcare profession, we advocate the use of modern imaging technologies to enhance student understanding and motivation and cognisance of the core syllabus for the subject being developed by the International Federation of Associations of Anatomists (IFAA).

P04.22 Tumor treating fields in high-grade glioma patients: A retrospective single-center study

BACKGROUND

Tumor-treating fields (TTFields) are a modern anti-mitotic, non-invasive therapy for the treatment of patients with recurrent and newly diagnosed glioblastoma multiforme (GBM). In Europe, Optune® recieved in 2015 the CE certification. TTFields are a low-intensity (1–3 V/cm) approved therapeutic modality using a non-invasive application of intermediate frequency (200 kHz) alternating electric fields through four transducer arrays directly applied to the skin. The EF-14 study has shown that the addition of TTFields to temozolomide chemotherapy in patients with newly diagnosed GBM significantly improved overall survival (OS) and progression-free survival (PFS) without additional adverse events, apart from mild to moderate skin irritations (Stupp et al., JAMA 2017).

MATERIAL

We retrospectively analyzed data from TTFields-treated patients (2015–2020) that were treated at our department. Patient characteristics such as MGMT promoter methylation status, age, and diagnosis, as well as treatment duration and TTFields therapy usage, were evaluated for this study.

RESULTS

29 patients were treated with TTFields therapy between 2015 and 2020 at our hospital. Most patients received TTFields as primary treatment together with temozolomide maintenance therapy. In detail, 48% of patients were diagnosed with newly diagnosed GBM, 41% received TTFields therapy after tumor recurrence and 10% were diagnosed with other high-grade gliomas. In summary, patients could integrate TTFields therapy into their daily life and showed high adherence to the therapy.Particularly, one of our patients (with MGMT-promoter methylation positive) receives TTFields therapy now for almost 1229 days (approx. 41 months) and is still on therapy. Additionally, this patient shows a high usage rate of 86% indicating well integration of the therapy into daily life.

CONCLUSION

Taken together, our data provided the outcomes of using TTFields together with chemotherapy in the treatment of recurrent and newly diagnosed GBM in our department. Therapy with TTFields has been showing to provide significant clinical benefit for GBM patients.

A-147 The Relationship of FSIQ and Executive Functioning Performance to a Self-Report Measure of Shifting (BRIEF-Shift)

Objective

This study aimed to clarify the relationship between a self-report measure of set-shifting and performance-based measures of set-shifting as compared to FSIQ using the Trail Making Test-Part B (TMT-B), Wisconsin Card Sorting Test (WCST) perseverative responses, Behavior Rating Inventory of Executive Function-Adult Version (BRIEF-A) self-report shift index, and the full-scale intelligence quotient (FSIQ) from the Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV).

Method

Data from 65 individuals (34 females, mean age 36) from an outpatient clinic in Chicagoland was analyzed using 2 block-wise hierarchical regression analyses with BRIEF-A shift as the outcome variable and TMT-B, WCST, and WAIS-IV FSIQ data as the predictor variables.

Results

Intelligence accounted for 4.7% (R2 = 0.047, p = 0.08) of the unique variance in BRIEF-A Shift self-report. In contrast, the TMT-B and WCST data accounted for little unique variance in the model and was to significantly correlated (R2 = 0.028, p = 0.416).

Conclusion

The current data somewhat surprisingly indicates that FSIQ is a more robust predictor of BRIEF Shift than performance-based measures of cognitive flexibility. Implications including an understanding of response bias, general aptitude, and normative comparisons will be discussed.

A pre-registered short-term forecasting study of COVID-19 in Germany and Poland during the second wave

Disease modelling has had considerable policy impact during the ongoing COVID-19 pandemic, and it is increasingly acknowledged that combining multiple models can improve the reliability of outputs. Here we report insights from ten weeks of collaborative short-term forecasting of COVID-19 in Germany and Poland (12 October-19 December 2020). The study period covers the onset of the second wave in both countries, with tightening non-pharmaceutical interventions (NPIs) and subsequently a decay (Poland) or plateau and renewed increase (Germany) in reported cases. Thirteen independent teams provided probabilistic real-time forecasts of COVID-19 cases and deaths. These were reported for lead times of one to four weeks, with evaluation focused on one- and two-week horizons, which are less affected by changing NPIs. Heterogeneity between forecasts was considerable both in terms of point predictions and forecast spread. Ensemble forecasts showed good relative performance, in particular in terms of coverage, but did not clearly dominate single-model predictions. The study was preregistered and will be followed up in future phases of the pandemic.

Cor Triatriatum Sinistrum Combined with Changes in Atrial Septum and Right Atrium in a 60-Year-Old Woman

Background and Objectives: A rare case of cor triatriatum sinistrum in combination with anomalies in the atrial septum and in the right atrium of a 60-year-old female body donor is described here. Materials and Methods: In addition to classical dissection, ultrasound and magnetic resonance imaging, computer tomography and cinematic rendering were performed. In a reference series of 59 regularly formed hearts (33 men, 26 women), we looked for features in the left and right atrium or atrial septum. In addition, we measured the atrial and ventricular wall thickness in 15 regularly formed hearts (7 men, 8 women). Results: In the case described, the left atrium was partly divided into two chambers by an intra-atrial membrane penetrated by two small openings. The 2.5 cm-high membrane originated in the upper level of the oval fossa and left an opening of about 4 cm in diameter. Apparently, the membrane did not lead to a functionally significant flow obstruction due to the broad intra-atrial communication between the proximal and distal chamber of the left atrium. In concordance with this fact, left atrial wall thickness was not elevated in the cor triatriatum sinistrum when compared with 15 regularly formed hearts. In addition, two further anomalies were found: 1. the oval fossa was deepened and arched in the direction of the left atrium; 2. the right atrium showed a membrane-like structure at its posterior and lateral walls, which began at the lower edge of the oval fossa. It probably corresponds to a strongly developed eustachian valve (valve of the inferior vena cava). Conclusions: The case described suggests that malformations in the development of the atrial septum and in the regression of the valve of the right sinus vein are involved in the pathogenesis of cor triatriatum sinistrum.

Modeling Radiation-Induced Neoplastic Cell Transformation In Vitro and Tumor Induction In Vivo with the Local Effect Model

Ionizing radiation induces DNA damage to cycling cells which, if left unrepaired or misrepaired, can cause cell inactivation or heritable, viable mutations. The latter can lead to cell transformation, which is thought to be an initial step of cancer formation. Consequently, the study of radiation-induced cell transformation promises to offer insights into the general properties of radiation carcinogenesis. As for other end points, the effectiveness in inducing cell transformation is elevated for radiation qualities with high linear energy transfer (LET), and the same is true for cancer induction. In considering DNA damage as a common cause of both cell death and transformations, a worthwhile approach is to apply mathematical models for the relative biological effectiveness (RBE) of cell killing to also assess the carcinogenic potential of high-LET radiation. In this work we used an established RBE model for cell survival and clinical end points, the local effect model (LEM), to estimate the transformation probability and the carcinogenic potential of ion radiation. The provided method consists of accounting for the competing processes of cell inactivation and induction of transformations or carcinogenic events after radiation exposure by a dual use of the LEM. Correlations between both processes inferred by the number of particle impacts to individual cells were considered by summing over the distribution of hits that individual cells receive. RBE values for cell transformation in vitro were simulated for three independent data sets, which were also used to gauge the approach. The simulations reflect the general RBE systematics both in magnitude and in energy and LET dependence. To challenge the developed method, in vivo carcinogenesis was investigated using the same concepts, where the probability for cancer induction within an irradiated organ was derived from the probability of finding carcinogenic events in individual cells. The predictions were compared with experimental data of carcinogenesis in Harderian glands of mice. Again, the developed method shows the same characteristics as the experimental data. We conclude that the presented method is helpful to predictively assess RBE for both neoplastic cell transformation and tumor induction after ion exposure within a wide range of LET values. The theoretical concept requires a non-linear component in the photon dose response for carcinogenic end points as a precondition for the observed enhanced effects after ion exposure, thus contributing to a long debate in epidemiology. Future work will use the method for assessing cancer induction in radiation therapy and exposure scenarios frequently discussed in radiation protection.

Update of the particle irradiation data ensemble (PIDE) for cell survival

The particle irradiation data ensemble (PIDE) is the largest database of cell survival data measured after exposure to ion beams and photon reference radiation. We report here on the updated version of the PIDE database and demonstrate how to investigate generic properties of radiation dose response using these sets of raw data. The database now contains information of over 1100 pairs of photon and ion dose response curves. It provides the originally published raw data of cell survival in addition to given linear quadratic (LQ) model parameters. If available, the raw data were used to derive LQ model parameters in the same way for all experiments. To demonstrate the extent of the database and the variability among experiments we focus on the dose response curves after ion and photon radiation separately in a first step. Furthermore, we discuss the capability and the limitations of the database for analyzing properties of low and high linear energy transfer (LET) radiation response based on multiple experiments. PIDE is freely available to the research community under www.gsi.de/bio-pide.

Strong Shift to ATR-Dependent Regulation of the G2-Checkpoint after Exposure to High-LET Radiation

The utilization of high linear-energy-transfer (LET) ionizing radiation (IR) modalities is rapidly growing worldwide, causing excitement but also raising concerns, because our understanding of their biological effects is incomplete. Charged particles such as protons and heavy ions have increasing potential in cancer therapy, due to their advantageous physical properties over X-rays (photons), but are also present in the space environment, adding to the health risks of space missions. Therapy improvements and the protection of humans during space travel will benefit from a better understanding of the mechanisms underpinning the biological effects of high-LET IR. There is evidence that high-LET IR induces DNA double-strand breaks (DSBs) of increasing complexity, causing enhanced cell killing, owing, at least partly, to the frequent engagement of a low-fidelity DSB-repair pathway: alternative end-joining (alt-EJ), which is known to frequently induce severe structural chromosomal abnormalities (SCAs). Here, we evaluate the radiosensitivity of A549 lung adenocarcinoma cells to X-rays, α-particles and ⁵⁶Fe ions, as well as of HCT116 colorectal cancer cells to X-rays and α-particles. We observe the expected increase in cell killing following high-LET irradiation that correlates with the increased formation of SCAs as detected by mFISH. Furthermore, we report that cells exposed to low doses of α-particles and ⁵⁶Fe ions show an enhanced G₂-checkpoint response which is mainly regulated by ATR, rather than the coordinated ATM/ATR-dependent regulation observed after exposure to low doses of X-rays. These observations advance our understanding of the mechanisms underpinning high-LET IR effects, and suggest the potential utility for ATR inhibitors in high-LET radiation therapy.

Pump-probe X-ray holographic imaging of laser-induced cavitation bubbles with femtosecond FEL pulses

Cavitation bubbles can be seeded from a plasma following optical breakdown, by focusing an intense laser in water. The fast dynamics are associated with extreme states of gas and liquid, especially in the nascent state. This offers a unique setting to probe water and water vapor far-from equilibrium. However, current optical techniques cannot quantify these early states due to contrast and resolution limitations. X-ray holography with single X-ray free-electron laser pulses has now enabled a quasi-instantaneous high resolution structural probe with contrast proportional to the electron density of the object. In this work, we demonstrate cone-beam holographic flash imaging of laser-induced cavitation bubbles in water with nanofocused X-ray free-electron laser pulses. We quantify the spatial and temporal pressure distribution of the shockwave surrounding the expanding cavitation bubble at time delays shortly after seeding and compare the results to numerical simulations.

Prevalence and characteristics of test anxiety in first year anatomy students

BACKGROUND

Test anxiety is a common phenomenon at universities with the potential to impair academic performance and student well-being. This study was conducted to investigate prevalence, characteristics, and development of the test anxiety categories "emotionality", "worry", "interference", and "lack of confidence" among first year medical students.

METHODS

Overall, 625 freshman medical students were enrolled. They were recruited from the participants of a first semester anatomy course. The participants were assessed four times with a validated psychological test anxiety questionnaire (Prüfungsangstfragebogen, PAF). The first assessment was conducted at the commencement of the first semester. All further assessments were performed two days prior to each of three mandatory oral anatomy tests in the course of one half year. Prevalence rates as well as mean global and subscale scores of the test anxiety dimensions "emotionality", "worry", "interference" and "lack of confidence" were determined and compared between assessments.

RESULTS

Approximately 50% of the study participants showed pronounced test anxiety in at least one dimension over the observation period. Only about 10% were considered test anxiety-positive according to the global PAF scale. Worry showed the highest (up to 48%) and interference the lowest (≈5%) prevalence rates. Emotionality had a stable prevalence of approximately 17%, whereas lack of confidence showed a rising trend over the observation period from 15.2% up to 24.0%.

CONCLUSION

Test anxiety is substantially more prevalent among medical students as commonly reported and deserves more detailed, dimension-specific exploration in future. Especially worry and lack of confidence give reason for concern, demanding further investigation.

Resilience and sense of coherence in first year medical students - a cross-sectional study

BACKGROUND

A broad range of studies show that medical students often have a significantly deteriorated mental health status. Although starting medical school with values comparable to the population average, only a few semesters later, medical undergraduates show increased rates of psychological risk states and some manifest mental illnesses, such as burnout and depression. In our survey we intentionally assessed mental health parameters from a salutogenetic, i.e. resource-oriented point of view.

METHODS

We examined first-year medical students in a cross-sectional study and assessed sense of coherence (SOC) and resilience as parameters from the salutogenesis model by Antonovsky in a structured way using validated, self-administered questionnaires. In total, we examined 236 students of human medicine, dentistry and molecular medicine at the Friedrich-Alexander-University Erlangen-Nürnberg (FAU).

RESULTS

Our analyses showed significantly higher values of resilience among male students compared to female students (p < 0.01). In contrast, even though a significant correlation between resilience and SOC was observed, only a non-significantly lower value of SOC was found in female students. Compared to the reference sample our medical students in their first year of study showed significantly lower values for resilience (p < 0.01) and SOC (p < 0.01).

CONCLUSION

Resilience and SOC are known to correlate with psychological stress (burnout parameters) and depression. In order to keep protective factors like SOC and resilience in medical students at a good and healthy level we see the necessity to address that problem proactively and educationally. Integrating training focused on the preservation of the students´ own mental health into the medical curriculum from the beginning of university courses, and throughout the whole medical study course, is essential and should be an obligatory training goal. Based on our study results, we also deem it necessary to think about ways to adapt the measures for the gender-specific needs of our students, e.g. dependent on their biological gender.

Materials Imaging and Dynamics (MID) instrument at the European X-ray Free-Electron Laser Facility

The Materials Imaging and Dynamics (MID) instrument at the European X-ray Free-Electron Laser (EuXFEL) facility is described. EuXFEL is the first hard X-ray free-electron laser operating in the MHz repetition range which provides novel science opportunities. The aim of MID is to enable studies of nano-structured materials, liquids, and soft- and hard-condensed matter using the bright X-ray beams generated by EuXFEL. Particular emphasis is on studies of structure and dynamics in materials by coherent scattering and imaging using hard X-rays. Commission of MID started at the end of 2018 and first experiments were performed in 2019.

Cinematic Rendering in Anatomy: A Crossover Study Comparing a Novel 3D Reconstruction Technique to Conventional Computed Tomography

Integration of medical imaging into preclinical anatomy courses is already underway in many medical schools. However, interpretation of two-dimensional grayscale images is difficult and conventional volume rendering techniques provide only images of limited quality. In this regard, a more photorealistic visualization provided by Cinematic Rendering (CR) may be more suitable for anatomical education. A randomized, two-period crossover study was conducted from July to December 2018, at the University Hospital of Erlangen, Germany to compare CR and conventional computed tomography (CT) imaging for speed and comprehension of anatomy. Sixteen students were randomized into two assessment sequences. During each assessment period, participants had to answer 15 anatomy-related questions that were divided into three categories: parenchymal, musculoskeletal, and vascular anatomy. After a washout period of 14 days, assessments were crossed over to the respective second reconstruction technique. The mean interperiod differences for the time to answer differed significantly between the CR-CT sequence (-204.21 ± 156.0 seconds) and the CT-CR sequence (243.33 ± 113.83 seconds; P < 0.001). Overall time reduction by CR was 65.56%. Cinematic Rendering visualization of musculoskeletal and vascular anatomy was higher rated compared to CT visualization (P < 0.001 and P = 0.003), whereas CT visualization of parenchymal anatomy received a higher scoring than CR visualization (P < 0.001). No carryover effects were observed. A questionnaire revealed that students consider CR to be beneficial for medical education. These results suggest that CR has a potential to enhance knowledge acquisition and transfer from medical imaging data in medical education.

Feasibility of Clinical Hypnosis for Test Anxiety in First-Year Medical Students

The purpose of this pilot study was to characterize test anxiety among first-year medical students at the University of Erlangen-Nürnberg and to test clinical hypnosis as a possible intervention. The "Prüfungsangstfragebogen," a shortened and revised German version of the Test Anxiety Inventory, was used to estimate test anxiety. It was administered 3 times: at the commencement of winter term 2017/18 and 2 days prior to each of 2 mandatory oral anatomy exams. The test-anxiety categories emotionality, worry, interference, and lack of confidence were evaluated. The effect of clinical hypnosis on test anxiety was estimated. The global test anxiety and lack of confidence scores were reduced significantly over time in the group that underwent clinical hypnosis but not in the control group. Direct comparisons of hypnosis vs. control group yielded no statistically significant differences in the test anxiety scores.

Neutrophil Extracellular Traps Promote the Development and Growth of Human Salivary Stones

Salivary gland stones, or sialoliths, are the most common cause of the obstruction of salivary glands. The mechanism behind the formation of sialoliths has been elusive. Symptomatic sialolithiasis has a prevalence of 0.45% in the general population, is characterized by recurrent painful periprandial swelling of the affected gland, and often results in sialadenitis with the need for surgical intervention. Here, we show by the use of immunohistochemistry, immunofluorescence, computed tomography (CT) scans and reconstructions, special dye techniques, bacterial genotyping, and enzyme activity analyses that neutrophil extracellular traps (NETs) initiate the formation and growth of sialoliths in humans. The deposition of neutrophil granulocyte extracellular DNA around small crystals results in the dense aggregation of the latter, and the subsequent mineralization creates alternating layers of dense mineral, which are predominantly calcium salt deposits and DNA. The further agglomeration and appositional growth of these structures promotes the development of macroscopic sialoliths that finally occlude the efferent ducts of the salivary glands, causing clinical symptoms and salivary gland dysfunction. These findings provide an entirely novel insight into the mechanism of sialolithogenesis, in which an immune system-mediated response essentially participates in the physicochemical process of concrement formation and growth.

Eignung eines mobilen Trockenelektroden-EEG-Gerätes im Rahmen der Epilepsiediagnostik

EEG-Aufzeichnungen bei Verdacht auf Epilepsie erfolgen routinemäßig mit einer durchschnittlichen Ableitezeit von 20–30 Min. mittels stationärer Geräte. Längere und häufigere Ableitungen, auch in der Häuslichkeit der Patienten, erhöhen die Wahrscheinlichkeit, Ereignisse zu erfassen. Die technische Qualität und medizinische Auswertbarkeit der EEG-Aufzeichnungen sind Grundvoraussetzungen für ein Home-Monitoring. Die HOMEEPI Studie prüft die technische Verwertbarkeit und Wirksamkeit eines mobilen EEG-Gerätes mit Trockenelektroden (Fourier ONE) im Vergleich zu einem konventionellen EEG-Gerät bei 49 Patienten mit Verdacht auf Epilepsie. Die Studienergebnisse basieren auf Intra- und Interratervergleichen und belegen eine vergleichbare Qualität der EEG-Aufzeichnungen und eine hohe Übereinstimmungsrate der medizinischen Befunde.

Prognostic importance of primary tumor resection and synchronous metastasis on overall survival in metastatic colorectal cancer: Data from the FIRE-3 (AIO KRK-0306) study

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Background: The FIRE-3 study (AIO KRK-0306) was designed as a randomized multicenter trial to compare the efficacy of FOLFIRI plus cetuximab (cet) to FOLFIRI plus bevacizumab (bev) as first-line treatment in KRAS WT mCRC patients. FOLFIRI plus cet as first-line treatment of KRAS WT mCRC patients resulted in comparable overall response rates (ORR) and progression free survival (PFS) when compared to FOLFIRI plus bev. Overall survival (OS) was significantly longer in the FOLFIRI plus cet arm. Methods: In the present analysis of the FIRE-3 trial we explored the impact of primary tumor resection on outcome in relation to anti-EGFR vs. anti-VEGF treatment. Furthermore, we investigated the prognostic value of synchronous versus metachronous metastases. Results: In patients with synchronous disease no significant difference in OS was detected when comparing resected (n=339) vs. non-resected (n=97) patients (p-value: 0.29, HR: 1.17, 95%-CI: 0.88 – 1.55). In the cetuximab arm, resection (n=167) showed no significant benefit in OS when compared to non-resection (n=52) (p-value: 0.51, HR: 1.15, 95%-CI: 0.77 – 1.71). Treated with bevacizumab, similar results were present, when comparing resection (n=172) vs. non-resection (n=45); (p-value: 0.29, HR: 1.25, 95%-CI: 0.83 – 1.9). A strong trend was seen when comparing OS in treatment arms cet. (n=219) vs. bev. (n=217)) for patients with synchronous disease; (p-value: 0.05, HR: 1,26, 95%-CI: 1.0 - 1.59). 436/592 pts suffered from synchronous, 153/592 from metachronous disease (in 3/592 pts the information was not given). Median OS in pts with synchronous disease was 24.5 months and 29.5 in pts with metachronous disease (p-value: 0.02, HR: 0.76, 95%-CI: 0.6 - 0.96). In pts treated in the cetuximab arm metachronous disease (n=77) was associated with a trend towards longer OS when compared to synchronous disease (n= 219) (p-value: 0.13, HR: 0.76, 95%-CI: 0.54 – 1.1). The same effect was present in the bevacizumab arm (p-value: 0.05, HR: 0.73, 95%-CI 0.53 – 1.0) when comparing pts with synchronous disease (n=217) vs. pts. with metachronous disease (n=76). Conclusions: In the FIRE-3 study, metachronous disease was associated with superior OS compared to synchronous disease. This finding was accentuated in the bevacizumab arm. The role of resection of the primary tumor had no impact on survival. Clinical trial information: NCT00433927 .

Two-level ACDF with a zero-profile stand-alone spacer compared to conventional plating: a prospective randomized single-center study

PURPOSE

Stand-alone zero-profile devices have already proven safety, and a reduced dysphagia rate was assumed. So far, no level-one evidence is available to prove the proposed advantages of zero-profile implants in multilevel procedures. The aim of this RCT was to compare the clinical and radiological outcome of a zero-profile spacer versus cage + plate in two-level ACDF.

METHODS

Consecutive patients with contiguous two-level cDD were randomly assigned either to the interventional group (zero-profile device) or to the control group (cage + plate). Primary endpoint of the study was the prevalence of dysphagia at 24 months. Disability, progress of adjacent segment degeneration, fusion status and loss of correction were analyzed as secondary outcome measure. Primary outcome parameter was statistically analyzed by Chi-square test.

RESULTS

Forty-one patients met inclusion criteria and were randomly assigned to the interventional and the control group. Dysphagia was frequent in either group at 3 months FU favoring interventional group (p = 0.078). At final FU, less patients of the interventional group complained about dysphagia, but the difference was not significant. No relevant differences at final FU were recorded for NPDI, loss of correction and adjacent-level degeneration. Fusion rate was slightly lower in the interventional group.

DISCUSSION

Two-level ACDF either by a stand-alone zero-profile spacer or cage + plate is safe. Using a zero-profile cage dysphagia was infrequent at 24 months, but the value did not reach statistical significance in comparison with the cage + plate. Hence, this randomized trial was not able to prove the proposed clinical superiority for dysphagia rates for zero-profile anchored spacer in two-level cDD.

Does zinc supplementation enhance the clinical efficacy of chloroquine/hydroxychloroquine to win today's battle against COVID-19?

Currently, drug repurposing is an alternative to novel drug development for the treatment of COVID-19 patients. The antimalarial drug chloroquine (CQ) and its metabolite hydroxychloroquine (HCQ) are currently being tested in several clinical studies as potential candidates to limit SARS-CoV-2-mediated morbidity and mortality. CQ and HCQ (CQ/HCQ) inhibit pH-dependent steps of SARS-CoV-2 replication by increasing pH in intracellular vesicles and interfere with virus particle delivery into host cells. Besides direct antiviral effects, CQ/HCQ specifically target extracellular zinc to intracellular lysosomes where it interferes with RNA-dependent RNA polymerase activity and coronavirus replication. As zinc deficiency frequently occurs in elderly patients and in those with cardiovascular disease, chronic pulmonary disease, or diabetes, we hypothesize that CQ/HCQ plus zinc supplementation may be more effective in reducing COVID-19 morbidity and mortality than CQ or HCQ in monotherapy. Therefore, CQ/HCQ in combination with zinc should be considered as additional study arm for COVID-19 clinical trials.

Comparison between a wireless dry electrode EEG system with a conventional wired wet electrode EEG system for clinical applications

Dry electrode electroencephalogram (EEG) recording combined with wireless data transmission offers an alternative tool to conventional wet electrode EEG systems. However, the question remains whether the signal quality of dry electrode recordings is comparable to wet electrode recordings in the clinical context. We recorded the resting state EEG (rsEEG), the visual evoked potentials (VEP) and the visual P300 (P3) from 16 healthy subjects (age range: 26-79 years) and 16 neurological patients who reported subjective memory impairment (age range: 50-83 years). Each subject took part in two recordings on different days, one with 19 dry electrodes and another with 19 wet electrodes. They reported their preferred EEG system. Comparisons of the rsEEG recordings were conducted qualitatively by independent visual evaluation by two neurologists blinded to the EEG system used and quantitatively by spectral analysis of the rsEEG. The P100 visual evoked potential (VEP) and P3 event-related potential (ERP) were compared in terms of latency, amplitude and pre-stimulus noise. The majority of subjects preferred the dry electrode headset. Both neurologists reported that all rsEEG traces were comparable between the wet and dry electrode headsets. Absolute Alpha and Beta power during rest did not statistically differ between the two EEG systems (p > 0.05 in all cases). However, Theta and Delta power was slightly higher with the dry electrodes (p = 0.0004 for Theta and p < 0.0001 for Delta). For ERPs, the mean latencies and amplitudes of the P100 VEP and P3 ERP showed comparable values (p > 0.10 in all cases) with a similar spatial distribution for both wet and dry electrode systems. These results suggest that the signal quality, ease of set-up and portability of the dry electrode EEG headset used in our study comply with the needs of clinical applications.