Lars Fester’s research while affiliated with University of Bonn and other places

To date, neuroanatomy education courses are still based on two-dimensional (2D) illustrations combined with cadaver dissections. To gain a more comprehensive understanding of neuroanatomy, we offered mixed reality experience using a head-mounted device (HMD) for medical students during their neuroanatomy course. This pilot study´s purpose was to determine whether or not, from a pragmatic view, the utilization of 3D VR/AR via HMD is viable in neuroanatomy courses and aimed to evaluate the feasibility of using mixed reality in neuroanatomy education and experiences with the mixed reality brain environment. A virtual model including major neuroanatomical structures was generated from a MRI dataset using computer software. Major structures were displayed and annotated in different combinations and scenes using an HMD. Along with the 3D virtual model, the original MRI was presented in a virtual form inside the HMD. Conventional 2D anatomical atlases were also used during the seminar. Thirty medical students (11 male; 19 female; average: 23.2 years) in their second year were recruited from October 2022 to February 2023 for this study via open invitation during neuroanatomy lectures. Participants were asked to wear the HMDs and to take a 2 h neurosurgery-oriented mixed reality seminar given by a neurosurgical teacher in small groups (3 per group). A questionnaire comprising five levels of options was designed and used to evaluate the feasibility/effectiveness of this seminar. The mixed reality environment, comprising virtual 3D models of major brain structures, virtual MRI, and conventional 2D anatomical graphs, was uncomplicated and feasible for neuroanatomy education of the medical students. According to our survey, all participants (30/30) strongly agreed that the 3D visualization of the spatial relationships between anatomical structures was easy to use as a meaningful supplement. Twenty-one of the participants strongly agreed and nine quite agreed that they had more interest in neuroanatomy. Eighty-seven percent of the participants were strongly satisfied with the mixed reality seminar versus conventional neuroanatomy seminars, and the other 13% were quite satisfied with the mixed reality approach. Most of the participants (20/30) strongly agreed that mixed reality helped them memorize the anatomical structures, and 9/30 participants quite agreed. Seventy-four percent of the participants agreed that immersive mixed reality is better than 3D models presented in 2D devices. Over half of the participants could wear the HMD for over 60 min (65%) without any ophthalmic discomfort, and the HMD was reported to be well tolerable (57%). Nearly three-fourths of the participants found that handling the device was extremely simple, and the other part indicated that it was quite simple. No health issues or discomfort on the forehead occurred. As a consequence, the seminar has been officially classified as an elective neuroanatomy course for second-year medical students. The use of mixed reality with HMDs to illustrate 3D brain models relevant for the neuroanatomy cadaver dissection education and described in our study was positively perceived by the medical students and demonstrated the viability of 3D AR/VR via HMD in neuroanatomy education. Future research lines are warranted to determine the usefulness of mixed reality technologies to effectively support medical students education of the complex three-dimensional brain anatomy.

Background With mortality rates up to 40% under optimal medical treatment, infectious endocarditis (IE) remains one of the deadliest infectious diseases worldwide. In the early stages of IE, diagnosis and treatment initiation are often difficult and research is limited due to unreliable models. Most murine IE models rely on permanent prosthetic wire placement and i.v. bacterial injection, thus making it inadequate to study IE pathophysiology with the aim to reflect the course of disease in humans. Purpose To develop a reproducible murine IE model, based on aortic valve injury preceding intravenous S. aureus bacterial challenge. Methods Using a wire-injury model we induced endothelial lesions. 72h after wire injury (WI), we performed intravenous bacterial challenge using S. aureus. Echocardiography was performed to confirm bacterial vegetations and assess valvular function. Cross sections of valvular leaflets were prepared for scanning electron microscopy (SEM). Macrophage, neutrophil and S. aureus-specific immunofluorescence staining was performed and visualized by immunofluorescence microscopy. Bacterial cultivation was performed from peripheral blood and valve tissue. Systemic immune response was analyzed using flow cytometry. Results WI induced endothelial damage in all mice verified using scanning electron microscopy imaging. The combination of wire injury and injection of 10^5 and 10^6 colonies-forming-units (CFU) S. aureus reliably caused IE validated via in vivo echocardiography as well as S.aureus immunofluorescence staining and SEM imaging. Mice undergoing bacterial challenge responded with significant neutrophilia in the blood. Using 10^6 CFU S. aureus was associated with an increased mortality, liver and kidney abscess formation due to systemic bacterial spreading compared to 10^5 CFU. Peak velocity across the aortic valve and aortic valve leaflet thickness as markers for aortic valve stenosis were increased in IE compared to WI only mice. Aortic regurgitation was more prevalent after bacterial challenge mediating increased left ventricular volumes, meanwhile ejection fraction was not altered. Immunofluorescence staining revealed a pro-inflammatory milieu including increased macrophage and neutrophil infiltration in IE compared to WI only mice. Conclusion In vivo echocardiography and ex vivo histological staining revealed reliable IE induction using our new model with S. aureus concentrations of 10^5 CFU. The additional bacterial challenge causes a more severe aortic valve stenosis compared to WI only mice, potentially due to an observed increase in valvular inflammation.Fig 1 Scanning electron microscopy after

Aim Brown adipose tissue (BAT) thermogenesis has profound energy‐expanding potential, which makes it an attractive target tissue to combat ever‐increasing obesity and its other associated metabolic complications. Although it is fairly accepted that cold is a potent inducer of BAT activation and function, there are limited studies on the mechanisms of pharmacological cold‐mimicking agents, such as the TRPM8 agonist, menthol, on BAT thermogenesis and activation. Methods Herein, we sought to determine the effect of topical application of menthol (10% w/v [4 g/kg] cream formulation/day for 15 days) on temperature sensitivity behaviour (thermal gradient assay, nesting behaviour), adaptive thermogenesis (infrared thermography, core body temperature), BAT sympathetic innervation (tyrosine hydroxylase immunohistochemistry) and activation (18F‐FDG PET‐CT analysis, Uncoupling Protein 1 immunohistochemistry and BAT gene expression), whole‐body energy expenditure (indirect calorimetry) and other metabolic variables in male C57BL/6N mice. Results We show that male C57BL/6N mice: (a) develop a warm‐seeking and cold‐avoiding thermal preference phenotype; (b) display increased locomotor activity and adaptive thermogenesis; (c) show augmented sympathetic innervation in BAT and its activation; (d) exhibit enhanced gluconeogenic capacity (increased glucose excursion in response to pyruvate) and insulin sensitivity; and (e) show enhanced whole‐body energy expenditure and induced lipid‐utilizing phenotype after topical menthol application. Conclusions: Taken together, our findings highlight that pharmacological cold mimicking using topical menthol application presents a potential therapeutic strategy to counter weight gain and related complications.

Incidence of Infective endocarditis (IE) and its mortality rate despite optimal medical therapy remain high. Early diagnosis and treatment initiation are challenging because the involved immunological processes are poorly understood due to a lack of suitable in vivo models and their difference to human pathophysiology. Objectives: To establish a novel reproducible murine IE model, based on wire injury (WI) induced endothelial damage. Methods: IE was established by inducing endothelial damage via wire injury followed by bacterial challenge with S. aureus using 104–6 colony-forming units (CFU). Cross-sections of valvular leaflets were prepared for scanning electron microscopy (SEM) and immunofluorescence microscopy to visualize valvular invasion of macrophages, neutrophils, and S. aureus. Bacterial cultivation was carried out from blood and valve samples. Results: Wire injury induced endothelial damage was observed in all mice after wire-injury in SEM imaging. We reliably induced IE using 10⁵ (85%) and 10⁶ (91%) CFU S. aureus after wire injury. We found significant neutrophilia in the blood and increased valvular immune cell and bacterial accumulations in IE mice. Conclusion: Our model allows for reliable IE induction and analysis of bacterial vegetation and immune cell infiltration in vivo and ex vivo. Valvular immune cell infiltration was similar to human pathophysiology.

Background Membranous nephropathy (MN) is caused by autoantibody binding to podocyte foot process antigens such as THSD7A and PLA 2 R1. The mechanisms of the glomerular antigen/autoantibody deposition and clearance are unknown. Methods We explore the origin and significance of glomerular accumulations in (1) diagnostic and follow-up biospecimens from THSD7A ⁺ and PLA 2 R1 ⁺ -MN patients compared to nephrotic non-MN patients, and (2) in experimental models of THSD7A ⁺ -MN. Results We discovered podocyte exophers as correlates of histological antigen/autoantibody aggregates found in the glomerular urinary space of MN patients. Exopher vesicle formation represents a novel form of toxic protein aggregate removal in Caenorhabditis elegans neurons. In MN patients, podocytes released exophers to the urine. Enrichment of exophers from MN patient urines established them as a glomerular exit route for antigens and bound autoantibody. Exophers also carried disease-associated proteins such as complement and provided a molecular imprint of podocyte injury pathways. In experimental THSD7A ⁺ -MN, exophers were formed from podocyte processes and cell body. Their formation involved the translocation of antigen/autoantibody from the subepithelial to the urinary side of podocyte plasma membranes. Urinary exopher-release correlated with lower albuminuria and lower glomerular antigen/autoantibody burden. In MN patients the prospective monitoring of urinary exopher abundance and of exopher-bound autoantibodies was additive in the assessment of immunologic MN activity. Conclusions Exopher-formation and release is a novel pathomechanism in MN to remove antigen/autoantibody aggregates from the podocyte. Tracking exopher-release will add a non-invasive diagnostic tool with prognostic potential to clinical diagnostics and follow-up of MN patients.

Background Membranous nephropathy (MN) is caused by autoantibody binding to podocyte foot process antigens such as THSD7A and PLA2R1. The mechanisms of the glomerular antigen/autoantibody deposition and clearance are unknown. Methods We explore the origin and significance of glomerular accumulations in (1) diagnostic and follow-up biospecimens from THSD7A⁺ and PLA2R1⁺-MN patients compared to nephrotic non-MN patients, and (2) in experimental models of THSD7A⁺-MN. Results We discovered podocyte exophers as correlates of histological antigen/autoantibody aggregates found in the glomerular urinary space of MN patients. Exopher vesicle formation represents a novel form of toxic protein aggregate removal in Caenorhabditis elegans neurons. In MN patients, podocytes released exophers to the urine. Enrichment of exophers from MN patient urines established them as a glomerular exit route for antigens and bound autoantibody. Exophers also carried disease-associated proteins such as complement and provided a molecular imprint of podocyte injury pathways. In experimental THSD7A⁺-MN, exophers were formed from podocyte processes and cell body. Their formation involved the translocation of antigen/autoantibody from the subepithelial to the urinary side of podocyte plasma membranes. Urinary exopher-release correlated with lower albuminuria and lower glomerular antigen/autoantibody burden. In MN patients the prospective monitoring of urinary exopher abundance and of exopher-bound autoantibodies was additive in the assessment of immunologic MN activity. Conclusions Exopher-formation and release is a novel pathomechanism in MN to remove antigen/autoantibody aggregates from the podocyte. Tracking exopher-release will add a non-invasive diagnostic tool with prognostic potential to clinical diagnostics and follow-up of MN patients.

Mitochondrial function plays an important role in the maintenance of male fertility. However, the mechanisms underlying mitochondrial defect-related infertility remain mostly unclear. Here we show that a deficiency of PARL (Parl−/−), a mitochondrial protease, causes complete arrest of spermatogenesis during meiosis I. PARL deficiency led to severe downregulation of proteins of respiratory chain complex IV in testes that did not occur in other tested organs, causing a deficit in complex IV activity and ATP production. Furthermore, Parl−/− testes showed an almost complete loss of HSD17B3, a protein of the sER responsible for the last step in testosterone synthesis. While testosterone production appeared to be restored by overexpression of HSD17B12, loss of the canonical testosterone synthesis led to an upregulation of luteinizing hormone (LH) and of LH-regulated responses. These results suggest an important impact of the downstream regulation of mitochondrial defects that manifest in a cell-type-specific manner and extend beyond mitochondria.

Introduction: To date, neuroanatomy education courses are still based on two-dimensional (2D) illustrations combined with cadaver dissections. To gain a more comprehensive understanding of neuroanatomy, we offered mixed reality experience using a head-mounted device(HMD) for medical students during their neuroanatomy course. This pilot study aimed to evaluate the feasibility of using mixed reality in neuroanatomy education and the acceptance and effectiveness of the mixed reality anatomy seminar for medical students. Methods: A virtual model including major neuroanatomical structures was generated from a MRI dataset using computer software. Major structureswere displayed and annotated in different combinations and scenes using an HMD. Along with the 3D virtual model, the original MRI was presented in a virtual form inside the HMD. Conventional 2D anatomical atlaseswere also used during the seminar. 30 medical students in their second year at Friedrich-Alexander University Erlangen-Nürnberg were recruited for this study via open invitation during neuroanatomy lectures. Participants were asked to wear the HMDs and to take a 2-hour neurosurgery-oriented mixed reality seminar given by a neurosurgical teacher in small groups (3 per group). A questionnaire comprising five levels of options was designed and used to evaluate the acceptance / effectiveness of this seminar. Results: The mixed reality enviroment, comprising virtual 3D models of major brain structures, virtual MRI, and conventional 2D anatomical graphs, was uncomplicated and feasible for neuroanatomy education of the medical students. According to our survey, all participants (30/30) strongly agreed that the 3D visualization of the spatial relationships between anatomical structures was easy to use as a meaningful supplement. Twenty-one of the participants strongly agreed and nine quite agreed that they had more interest in neuroanatomy. Eighty-seven percentof the participants were strongly satisfied with the mixed reality seminar versus conventional neuroanatomy seminars, and the other 13% were quite satisfied with the mixed reality approach. Most of the participants (20/30) strongly agreed that mixed reality helped them memorize the anatomical structures, and 9/30 participants quite agreed. Seventy-four percentof the participants agreed that immersive mixed reality is better than 3D models presented in 2D devices. Over half of the participants could wear the HMD for over 60 minutes (65%) without any ophthalmic discomfort, and the HMD was reported to be well tolerable (57%). Nearly three-fourthsof the participants found that handling the device was extremely simple, and the other part indicated that it was quite simple. No health issues or discomfort on the forehead occurred. As a consequence, the seminar has been officially classified as an elective neuroanatomy course for second-year medical students. Conclusions: Using mixed reality with HMDs to conduct neuroanatomy education to supplement conventional lectures and cadaver dissection is feasible. The mixed-reality seminar described in our study was quite acceptable for medical students and promoted increased interest in neurosurgery. Most importantly, mixed reality could help medical students more efficiently understand and memorize the major structures and their dimensional relationships in neuroanatomy.

Sepsis is a dysregulated host response of severe bloodstream infections, and given its frequency of occurrence and high mortality rate, therapeutic improvements are imperative. A reliable biomimetic strategy for the targeting and separation of bacterial pathogens in bloodstream infections involves the use of the broad-spectrum binding motif of human GP-340, a pattern-recognition receptor of the scavenger receptor cysteine rich (SRCR) superfamily that is expressed on epithelial surfaces but not found in blood. Here we show that these peptides, when conjugated to superparamagnetic iron oxide nanoparticles (SPIONs), can separate various bacterial endotoxins and intact microbes (E. coli, S. aureus, P. aeruginosa and S. marcescens) with high efficiency, especially at low and thus clinically relevant concentrations. This is accompanied by a subsequent strong depletion in cytokine release (TNF, IL-6, IL-1β, Il-10 and IFN-γ), which could have a direct therapeutic impact since escalating immune responses complicates severe bloodstream infections and sepsis courses. SPIONs are coated with aminoalkylsilane and capture peptides are orthogonally ligated to this surface. The particles behave fully cyto- and hemocompatible and do not interfere with host structures. Thus, this approach additionally aims to dramatically reduce diagnostic times for patients with suspected bloodstream infections and accelerate targeted antibiotic therapy. Statement of significance : Sepsis is often associated with excessive release of cytokines. This aspect and slow diagnostic procedures are the major therapeutic obstacles. The use of magnetic particles conjugated with small peptides derived from the binding motif of a broad-spectrum mucosal pathogen recognition protein GP-340 provides a highly efficient scavenging platform. These peptides are not found in blood and therefore are not subject to inhibitory mechanisms like in other concepts (mannose binding lectine, aptamers, antibodies). In this work, data are shown on the broad bacterial binding spectrum, highly efficient toxin depletion, which directly reduces the release of cytokines. Host cells are not affected and antibiotics not adsorbed. The particle bound microbes can be recultured without restriction and thus be used directly for diagnostics.