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Internationally, scientific and research-related competencies need to be sufficiently targeted as core outcomes in many undergraduate medical curricula. Since 2015, standards have been recommended for Germany in the National Competency-based Learning Objective Catalogue in Medicine (NKLM). The aim of this study is to develop a multi-center mapping approach for curricular benchmarking against national standards and against other medical faculties.A total of 277 faculty members from four German medical faculties have mapped the local curriculum against the scientific and research-related NKLM objectives, using consented procedures, metrics, and tools. The amount of mapping citations of each objective is used as indicator for its weighting in the local curriculum. Achieved competency levels after five-year education are compared.All four programs fulfill the NKLM standards, with each emphasizing different sub-competencies explicitly in writing (Scholar: 17-41% of all courses; Medical Scientific Skills: 14-37% of all courses). Faculties show major or full agreement in objective weighting: Scholar 44%, scientific skills 79%. The given NKLM competency level is met or even outperformed in 78-100% of the courses.The multi-center mapping approach provides an informative dataset allowing curricular diagnosis by external benchmarking and guidance for optimization of local curricula.

Objectives: Transition to competency-based medical education is a highly challenging endeavor. Students, teachers and institutions need curricular transparency for understanding the build-up of competencies in terms of coverage, sequence and consistence of learning objectives and assessment. The project aim was to develop and implement a web-based interactive platform for curriculum mapping, diagnostics, and development. The tool should be transferable to other faculties and allow description and visualization of medical curricula in comparison to given national competency-based standards. Methods: In a design-based multi-center approach, four German medical faculties cooperated and developed a standardized, common mapping tool (MERlin database). Implemented are techniques for big data handling and visual analytics. Results: The platform profile is adapted closely to user needs. Intuitive data entry and comfortable quality maintenance support teacher engagement. Individual navigation for curricular diagnostics is guided by practice-oriented questions. Sophisticated, easy-understandable visualizations show curricular strengths and weaknesses. Transparency in contributing departments facilitates goal-oriented dialogs. Currently, 14 of 38 German faculties use the platform. Conclusions: In view of huge amounts of data and complex curricular structures, the MERlin database facilitates effective curriculum mapping, goal-oriented curriculum development, comparison to national competency-based standards, effective data sharing and benchmarking across faculties with different curriculum management systems.

Objective: After passing of the National Competency-based Learning Objectives Catalogue in Medicine (Nationaler Kompetenzbasierter Lernzielkatalog Medizin, [NKLM, retrieved on 22.03.2016]), the German medical faculties must take inventory and develop their curricula. NKLM contents are expected to be present, but not linked well or sensibly enough in locally grown curricula. Learning and examination formats must be reviewed for appropriateness and coverage of the competences. The necessary curricular transparency is best achieved by systematic curriculum mapping, combined with effective change management. Mapping a complex existing curriculum and convincing a faculty that this will have benefits is not easy. Headed by Tübingen, the faculties of Freiburg, Heidelberg, Mannheim and Tübingen take inventory by mapping their curricula in comparison to the NKLM, using the dedicated web-based MERLIN-database. This two-part article analyses and summarises how NKLM curriculum mapping could be successful in spite of resistance at the faculties. The target is conveying the widest possible overview of beneficial framework conditions, strategies and results. Part I of the article shows the beneficial resources and structures required for implementation of curriculum mapping at the faculties. Part II describes key factors relevant for motivating faculties and teachers during the mapping process. Method: The network project was systematically planned in advance according to steps of project and change management, regularly reflected on and adjusted together in workshops and semi-annual project meetings. From the beginning of the project, a grounded-theory approach was used to systematically collect detailed information on structures, measures and developments at the faculties using various sources and methods, to continually analyse them and to draw a final conclusion (sources: surveys among the project participants with questionnaires, semi-structured group interviews and discussions, guideline-supported individual interviews, informal surveys, evaluation of target agreements and protocols, openly discernible local, regional or over-regional structure-relevant events). Results: The following resources and structures support implementation of curriculum mapping at a faculty: Setting up a coordination agency (≥50% of a full position; support by student assistants), systematic project management, and development of organisation and communication structures with integration of the dean of study and teaching and pilot departments, as well as development of a user-friendly web-based mapping instrument. Acceptance of the mapping was increased particularly by visualisation of the results and early insight into indicative results relevant for the department. Conclusion: Successful NKLM curriculum mapping requires trained staff for coordination, resilient communication structures and a user-oriented mapping database. In alignment with literature, recommendations can be derived to support other faculties that want to map their curriculum.

Objective: Arterial allografts are routinely employed for reconstruction of infected prosthetic grafts. Usually, banked cryopreserved arteries are used; however, existing conventional freezing cryopreservation techniques applied to arteries are expensive. In contrast, a new ice-free cryopreservation technique results in processing, storage and shipping methods that are technically simpler and potentially less costly. The objective of this study was to determine whether or not ice-free cryopreservation causes tissue changes that might preclude clinical use. Methods: Conventionally frozen cryopreserved porcine arteries were compared with ice-free cryopreserved arteries and untreated fresh controls using morphological (light, scanning electron and laser scanning microscopy), viability (alamarBlue assay) and hemocompatibility methods (blood cell adhesion, thrombin/antithrombin-III-complex, polymorphonuclear neutrophil-elastase, β-thromboglobulin and terminal complement complex SC5b-9). Results: No statistically significant structural or hemocompatibility differences between ice-free cryopreserved and frozen tissues were detectable. There were no quantitative differences observed for either autofluorescence (elastin) or second harmonic generation (collagen) measured by laser scanning microscopy. Cell viability in ice-free cryopreserved arteries was significantly reduced compared to fresh and frozen tissues (p < 0.05). Conclusions: The formation of ice in aortic artery preservation did not make a difference in histology, structure or thrombogenicity, but significantly increased viability compared with a preservation method that precludes ice formation. Reduced cell viability should not reduce in vivo performance. Therefore, ice-free cryopreservation is a potentially safe and cost-effective technique for the cryopreservation of blood vessel allografts.

Background: Age-related arterial alterations affecting cells, matrix and biomolecules are the main culprit for initiation and progression of cardiovascular disease. The objective of this study is to gain further insights into the complex mechanism of elastic tissue ageing in human aortic blood vessels. Methods: One hundred and nineteen human aortic tissue samples were collected from adult patients (101 males, 18 females; age 40–86 years) undergoing coronary artery bypass grafting. Overall extracellular matrix architecture was examined by multiphoton laser scanning microscopy and histology. Matrix metalloproteinases 2 and 9, corresponding tissue inhibitors 1 and 2 as well as desmosine were determined. mRNA levels of tropoelastin were assessed by quantitative RT-PCR. Results: Age-related destruction of the vascular elastic laminas as well as a loss of interlamina cross-links were observed by laser scanning microscopy. These results were confirmed by histology indicating increasing interlamina gaps. There were no significant differences in matrix turnover or desmosine content. A steady decrease in tropoelastin mRNA by about 50% per 10 years of age increase was observed. Conclusions: Our findings indicate that ageing is accompanied by a destruction of the elastic vascular structure. However, tropoelastin expression analysis suggests that elastogenesis occurs throughout life with constantly decreasing levels.

Transplantation of cryopreserved heart valves (allografts) is limited by immune responses, inflammation, subsequent structural deterioration and an expensive infrastructure. In previous studies we demonstrated that conventional frozen cryopreservation (FC) is accompanied by serious alterations of extracellular matrix (ECM) structures. As the main culprit of the observed damages ice crystal formation was identified. Objective of this study was the application principles of cryoprotection as observed in nature, occurring in animals or plants, for ice-free cryopreservation (IFC) of heart valves. Using IFC, valves were processed and stored above the glass transition temperature of the cryoprotectant formulation (-124 degrees C) at -80 degrees C to avoid any ice formation, tissue-glass cracking and preserving ECM. After implantation in the orthotopic pulmonary position in sheep, we demonstrate that IFC resulted in cell free matrices, while maintaining crucial ECM-components such as elastin and collagen, translating into superior hemodynamics. In contrast, we reveal that FC valves showed ECM damage that was not restored in vivo, and T-cell inflammation of the stroma with significant leaflet thickening. Compared to currently applied FC practice IFC also reduced infrastructural needs for preservation, storage and shipping. These results have important implications for clinical valve transplantation including the promise of better long-term function and lower costs.

Decellularized xenogeneic tissue represents an interesting material for heart valve tissue engineering. The prospect objective is removal of all viable cells while preserving extracellular matrix (ECM) integrity. The major concerns of all decellularization protocols remain ECM disruption, immunogenicity and thrombogenicity. Accordingly the aim of this study was visualization of ultrastructural ECM disruption and human immune response and thrombogenicity using different decellularization protocols of porcine heart valves. Porcine pulmonary leaflets were decellularized with four different protocols: sodium deoxycholate, sodium dedecylsulfate, trypsin/EDTA, and trypsin-detergent-nuclease. Then the tissues were processed for histology and two-photon laser scanning microscopy (LSM). For thrombogenicity and immunogenicity testing tissues were incubated with human blood. The histological examination revealed no remaining cells and no significant differences in the ECM histoarchitecture in any group. LSM detected significant ECM alterations in all groups except sodium deoxycholate group with an almost completely preserved ECM. There was no increased immunogenicity between fresh and decellularized tissue. Compared to GA-fixed tissue however significantly increased immune responses and thrombogenicity was observed in all protocols. From our experiment, sodium deoxycholate enables cell removal with almost complete preservation of ECM structures. And all of these four decellularization protocols affected human immunological response and increased thrombogenicity.

Current tissue-engineering principles of heart valves include tissue- or stem cell-derived cells with subsequent in vitro incubation on various scaffolds prior to implantation. Limitations of this approach include a long in vitro culture, an accompanied risk of infection and sophisticated, cost-intensive infrastructures. An ‘off-the-shelf’ heart valve with in vivo endothelialization and tissue-regeneration potential would overcome these limitations. Additionally, the development of a heart valve with growth potential would be a huge improvement for pediatric patients. This article discusses different starter matrices, homing and immobilization strategies of host cells and masking approaches of inflammatory structures for in vivo surface and tissue engineering of heart valves. Novel concepts will be presented based on highly specific DNA-aptamers immobilized on the heart valve surface as capture molecules for endothelial progenitor cells circulating in the bloodstream.

The visual process in rod cells is initiated by absorption of a photon in the rhodopsin retinal chromophore and consequent retinal cis/trans-isomerization. The ring structure of retinal is thought to be needed to transmit the photonic energy into conformational changes culminating in the active metarhodopsin II (Meta II) intermediate. Here, we demonstrate that cis-acyclic retinals, lacking four carbon atoms of the ring, can activate rhodopsin. Detailed analysis of the activation pathway showed that, although the photoproduct pathway is more complex, Meta II formed with almost normal kinetics. However, lack of the ring structure resulted in a low amount of Meta II and a fast decay of activity. We conclude that the main role of the ring structure is to maintain the active state, thus specifying a mechanism of activation by a partial agonist of the G protein-coupled receptor rhodopsin.

Objective To develop a novel 3-dimensional (3-D) in vitro model of Lyme arthritis to use in the study of the interactions between Borrelia burgdorferi (Bb) and human synovial host cells with respect to phagocytosis and potential persistence of Bb as well as the induction of proinflammatory cytokines and chemokines. Methods Two distinct culture systems, consisting of synovial membrane explants or interactive synovial cells embedded in 3-D fibrin matrices, were chosen. Both systems were artificially infected with Bb, and the interactions between Bb and synovial tissue/cells were studied by histology, immunohistochemistry, and electron microscopy. Functional analyses included the induction/secretion of cytokines by Bb in the model system. Results Both culture systems proved to be stable and reproducible. The host cells and spirochetes showed high levels of viability and maintained their physiologic shape for >3 weeks. Bb invaded the synovial tissue and the artifical matrix in a time-dependent manner. Host cells were activated by Bb, as indicated by the induction of interleukin-1β and tumor necrosis factor α. Electron microscopic analysis revealed Bb intracellularly within macrophages as well as synovial fibroblasts, suggesting that not only professional phagocytes, but also resident synovial cells are capable of phagocytosing Bb. Most interestingly, the uptake of the spirochetes appeared to cause severe damage of the synovial fibroblasts, since the majority of these cells displayed ultrastructural features of disintegration. Conclusion A novel 3-D in vitro model has been established that allows the study of distinct aspects of Lyme arthritis under conditions that resemble the pathologic condition in humans. This reproducible, standardized model supplements animal studies and conventional 2-D cultures. The disintegration of synovial fibroblasts containing Bb or Bb fragments challenges the concept of an intracellular persistence of Bb and may instead reflect a mechanism that contributes to the inflammatory processes characteristic of Lyme arthritis.

In vivoself-endothelialization by endothelial cell adhesion on cardiovascular implants is highly desirable. DNA-oligonucleotides are an intriguing coating material with nonimmunogenic characteristics and the feasibility of easy and rapid chemical fabrication. The objective of this study was the creation of cell adhesive DNA-oligonucleotide coatings on vascular implant surfaces. DNA-oligonucleotides immobilized by adsorption on parylene (poly(monoaminomethyl-para-xylene)) coated polystyrene and ePTFE were resistant to high shear stress (9.5 N/m2) and human blood serum for up to 96 h. Adhesion of murine endothelial progenitor cells, HUVECs and endothelial cells from human adult saphenous veins as well as viability over a period of 14 days of HUVECs on oligonucleotide coated samples under dynamic culture conditions was significantly enhanced (P<0.05). Oligonucleotide-coated surfaces revealed low thrombogenicity and excellent hemocompatibility after incubation with human blood. These properties suggest the suitability of immobilization of DNA-oligonucleotides for biofunctionalization of blood vessel substitutes for improvedin vivoendothelialization.

The purpose of this study was evaluation of an ice-free cryopreservation method for heart valves in an allogeneic juvenile pulmonary sheep implant model and comparison with traditionally frozen cryopreserved valves. Hearts of 15 crossbred Whiteface sheep were procured in Minnesota. The valves were processed in South Carolina and the pulmonary valves implanted orthotopically in 12 black faced Heidschnucke sheep in Germany. The ice-free cryopreserved valves were cryopreserved in 12.6 mol/l cryoprotectant (4.65, 4.65, and 3.31 mol/l of dimethylsulfoxide, formamide and 1,2-propanediol) and stored at −80°C. Frozen valves were cryopreserved by controlled slow rate freezing in 1.4 mol/l dimethylsulfoxide and stored in vapor-phase nitrogen. Aortic valve tissues were used to evaluate the impact of preservation without implantation. Multiphoton microscopy revealed reduced but not significantly damaged extracellular matrix before implantation in frozen valves compared with ice-free tissues. Viability assessment revealed significantly less metabolic activity in the ice-free valve leaflets and artery samples compared with frozen tissues (P

Long-term function of biological heart valve prostheses (BHV) is limited by structural deterioration leading to failure with associated arterial hypertension. The objective of this work was development of an easy to handle real-time pulse reactor for evaluation of biological and tissue engineered heart valves under different pressures and long-term conditions. The pulse reactor was made of medical grade materials for placement in a 37 degrees C incubator. Heart valves were mounted in a housing disc moving horizontally in culture medium within a cylindrical culture reservoir. The microprocessor-controlled system was driven by pressure resulting in a cardiac-like cycle enabling competent opening and closing of the leaflets with adjustable pulse rates and pressures between 0.25 to 2 Hz and up to 180/80 mmHg, respectively. A custom-made imaging system with an integrated high-speed camera and image processing software allow calculation of effective orifice areas during cardiac cycle. This simple pulse reactor design allows reproducible generation of patient-like pressure conditions and data collection during long-term experiments.

Multiphoton imaging is a powerful tool for three-dimensional visualization of extracellular matrix components such as collagen and elastin in fresh, nonfixed, and nonembedded tissues. We have previously published data on the induction of the second harmonic generation signal of collagen and autofluorescence of elastin using a tunable multiphoton laser system. Without staining, a second harmonic generation signal was detected for collagen when excited at wavelength lambda(ex) = 840 nm. Switching the excitation wavelength to 760 nm enabled visualization of elastic fiber structures. A limitation of this technology is the laser-tuning process that requires calibration of the system in between the studies. Now we have developed a facilitated method for studying tissues and tissue equivalents that enables simultaneous visualization of collagen and elastin structures using only a single excitation wavelength of 840 nm in combination with two different band-pass filters. This facilitated method will expand the range of application by reducing required time and expenses for the laser system without reducing its capability.

The visual process in rod cells is initiated by absorption of a photon in the rhodopsin retinal chromophore and consequent retinal cis/trans-isomerization. The ring structure of retinal is thought to be needed to transmit the photonic energy into conformational changes culminating in the active metarhodopsin II (Meta II) intermediate. Here, we demonstrate that cis-acyclic retinals, lacking four carbon atoms of the ring, can activate rhodopsin. Detailed analysis of the activation pathway showed that, although the photoproduct pathway is more complex, Meta II formed with almost normal kinetics. However, lack of the ring structure resulted in a low amount of Meta II and a fast decay of activity. We conclude that the main role of the ring structure is to maintain the active state, thus specifying a mechanism of activation by a partial agonist of the G protein-coupled receptor rhodopsin.

In the G protein-coupled receptor rhodopsin, the conserved NPxxY(x) 5,6 F motif connects the transmembrane helix VII and the cytoplasmic helix 8. The less geometrically constrained retinal analogue 9-demethyl-retinal prevents efficient transformation of rhodopsin to signaling metarhodopsin (Meta) II after retinal photoisomerization. Here, we demonstrate that Ala replacement mutations within the NPxxY(x) 5,6 F domain, which eliminate an interaction between aromatic residues Y306 and F313, allow formation of Meta II despite the presence of 9-demethyl-retinal. Also a disulfide bond linking residues 306 and 313 in the 9-demethyl-retinal-reconstituted mutant Y306C/F313C/C316S prevented Meta II formation, whereas the reduced form of the mutant readily transformed to Meta II after illumination. These observations suggest that the interaction between residues 306 and 313 is disrupted during the Meta I/Meta II transition. However, this enhancement in Meta II formation is not reflected in the G protein activation, which is dramatically reduced for these mutants, suggesting that changes in the Y306–F313 interaction also lead to a proper realigning of helix 8 after photoisomerization. The E134Q mutation, located in the second conserved motif, D(E)RY, rescues activity in 9-demethyl-retinal-reconstituted mutants to different degrees, depending on the position of the Ala replacement in the NPxxY(x) 5,6 F motif, thus revealing distinct roles for the NP and Y(x) 5,6 F portions. Our studies underscore the importance of the NPxxY(x) 5,6 F and D(E)RY motifs in providing structural constraints in rhodopsin that rearrange in response to photoisomerization during formation of the G protein-activating Meta II. The dual control of the structural rearrangements secures reliable transformation of quiescent rhodopsin to activating Meta II.