Crucial role of the terminal complement complex in chondrocyte death and hypertrophy after cartilage trauma.

OBJECTIVE: Innate immune response and particularly terminal complement complex (TCC) deposition are thought to be involved in the pathogenesis of posttraumatic osteoarthritis. However, the possible role of TCC in regulated cell death as well as chondrocyte hypertrophy and senescence has not been unraveled so far and was first addressed using an ex vivo human cartilage trauma-model. DESIGN: Cartilage explants were subjected to blunt impact (0.59 J) and exposed to human serum (HS) and cartilage homogenate (HG) with or without different potential therapeutics: RIPK1-inhibitor Necrostatin-1 (Nec), caspase-inhibitor zVAD, antioxidant N-acetyl cysteine (NAC) and TCC-inhibitors aurintricarboxylic acid (ATA) and clusterin (CLU). Cell death and hypertrophy/senescence-associated markers were evaluated on mRNA and protein level. RESULTS: Addition of HS resulted in significantly enhanced TCC deposition on chondrocytes and decrease of cell viability after trauma. This effect was potentiated by HG and was associated with expression of RIPK3, MLKL and CASP8. Cytotoxicity of HS could be prevented by heat-inactivation or specific inhibitors, whereby combination of Nec and zVAD as well as ATA exhibited highest cell protection. Moreover, HS+HG exposition enhanced the gene expression of CXCL1, IL-8, RUNX2 and VEGFA as well as secretion of IL-6 after cartilage trauma. CONCLUSIONS: Our findings imply crucial involvement of the complement system and primarily TCC in regulated cell death and phenotypic changes of chondrocytes after cartilage trauma. Inhibition of TCC formation or downstream signaling largely modified serum-induced pathophysiologic effects and might therefore represent a therapeutic target to maintain the survival and chondrogenic character of cartilage cells.

Neutrophils in Tissue Trauma of the Skin, Bone, and Lung: Two Sides of the Same Coin.

Following severe tissue injury, patients are exposed to various danger- and microbe-associated molecular patterns, which provoke a strong activation of the neutrophil defense system. Neutrophils trigger and modulate the initial posttraumatic inflammatory response and contribute critically to subsequent repair processes. However, severe trauma can affect central neutrophil functions, including circulation half-life, chemokinesis, phagocytosis, cytokine release, and respiratory burst. Alterations in neutrophil biology may contribute to trauma-associated complications, including immune suppression, sepsis, multiorgan dysfunction, and disturbed tissue regeneration. Furthermore, there is evidence that neutrophil actions depend on the quality of the initial stimulus, including trauma localization and severity, the micromilieu in the affected tissue, and the patient's overall inflammatory status. In the present review, we describe the effects of severe trauma on the neutrophil phenotype and dysfunction and the consequences for tissue repair. We particularly concentrate on the role of neutrophils in wound healing, lung injury, and bone fractures, because these are the most frequently affected tissues in severely injured patients.

A Conformational Change in C-Reactive Protein Enhances Leukocyte Recruitment and Reactive Oxygen Species Generation in Ischemia/Reperfusion Injury.

Introduction: C-reactive protein circulates as a pentameric protein (pCRP). pCRP is a well-established diagnostic marker as plasma levels rise in response to tissue injury and inflammation. We recently described pro-inflammatory properties of CRP, which are mediated by conformational changes from pCRP to bioactive isoforms expressing pro-inflammatory neo-epitopes [pCRP* and monomeric C-reactive protein (mCRP)]. Here, we investigate the role of CRP isoforms in renal ischemia/reperfusion injury (IRI). Methods: Rat kidneys in animals with and without intraperitoneally injected pCRP were subjected to IRI by the time of pCRP exposure and were subsequently analyzed for monocyte infiltration, caspase-3 expression, and tubular damage. Blood urea nitrogen (BUN) was analyzed pre-ischemia and post-reperfusion. CRP effects on leukocyte recruitment were investigated via intravital imaging of rat-striated muscle IRI. Localized conformational CRP changes were analyzed by immunohistochemistry using conformation specific antibodies. 1,6-bis(phosphocholine)-hexane (1,6-bisPC), which stabilizes CRP in its native pentameric form was used to validate CRP effects. Leukocyte activation was assessed by quantification of reactive oxygen species (ROS) induction by CRP isoforms ex vivo and in vitro through electron spin resonance spectroscopy. Signaling pathways were analyzed by disrupting lipid rafts with nystatin and subsequent ROS detection. In order to confirm the translational relevance of our findings, biopsies of microsurgical human free tissue transfers before and after IRI were examined by immunofluorescence for CRP deposition and co-localization of CD68+ leukocytes. Results: The application of pCRP aggravates tissue damage in renal IRI. 1,6-bisPC reverses these effects via inhibition of the conformational change that leads to exposure of pro-inflammatory epitopes in CRP (pCRP* and mCRP). Structurally altered CRP induces leukocyte-endothelial interaction and induces ROS formation in leukocytes, the latter can be abrogated by blocking lipid raft-dependent signaling pathways with Nystatin. Stabilizing pCRP in its native pentameric state abrogates these pro-inflammatory effects. Importantly, these findings are confirmed in human IRI challenged muscle tissue. Conclusion: These results suggest that CRP is a potent modulator of IRI. Stabilizing the native pCRP conformation represents a promising anti-inflammatory therapeutic strategy by attenuation of leukocyte recruitment and ROS formation, the primary pathomechanisms of IRI.

Janus face of complement-driven neutrophil activation during sepsis.

During local and systemic inflammation, the complement system and neutrophil granulocytes are activated not only by pathogens, but also by released endogenous danger signals. It is recognized increasingly that complement-mediated neutrophil activation plays an ambivalent role in sepsis pathophysiology. According to the current definition, the onset of organ dysfunction is a hallmark of sepsis. The preceding organ damage can be caused by excessive complement activation and neutrophil actions against the host, resulting in bystander injury of healthy tissue. However, in contrast, persistent and overwhelming inflammation also leads to a reduction in neutrophil responsiveness as well as complement components and thus may render patients at enhanced risk of spreading infection. This review provides an overview on the molecular and cellular processes that link complement with the two-faced functional alterations of neutrophils in sepsis. Finally, we describe novel tools to modulate this interplay beneficially in order to improve outcome.

Mesenchymal stem cells in peripheral blood of severely injured patients.

PURPOSE: Mesenchymal stem cells (MSCs) are primarily stromal cells present in bone marrow and other tissues that are crucial for tissue regeneration and can be mobilized into peripheral blood after different types of organ damage. However, little is known about MSC appearance in blood in the setting of polytrauma. METHODS: We conducted a monocentered and longitudinal observational clinical study in 11 polytraumatized patients with an injury severity score (ISS) ≥ 24 to determine the numbers of MSCs in peripheral blood. Blood was collected from healthy volunteers and patients after polytrauma in the emergency room and 4, 12, 24, 48 h, 5 and 10 day later, and cells carrying MSC-surface markers (negative for CD45, positive for CD29, CD73, CD90, CD105, and CD166 in different combinations also employing the more stringent markers STRO1 and MSCA1) were detected and characterized using flow cytometry. Relative numbers of MSC-like cells were correlated with clinical parameters to evaluate if specific injury patterns had an influence on their presence in the blood cell pool. RESULTS: We were able to detect MSC marker-positive cells in both cohorts; however, the percentage of those cells present in the blood of patients during the first 10 day after injury was mostly similar to healthy volunteers, and significantly lowers starting at 4 h post trauma for one marker combination when compared to controls. Furthermore, the presence of a pelvis fracture was partly correlated with reduced relative numbers of MSC-like cells detectable in blood. CONCLUSIONS: Polytrauma in humans was associated with partly reduced relative numbers of MSC-like cells detected in peripheral blood in the time course after injury. Further studies need to define if this reduction was due to lower mobilization from the bone marrow or to active migration to the sites of injury.

Cardiac Depression in Pigs after Multiple Trauma - Characterization of Posttraumatic Structural and Functional Alterations.

The purpose of this study was to define the relationship between cardiac depression and morphological and immunological alterations in cardiac tissue after multiple trauma. However, the mechanistic basis of depressed cardiac function after trauma is still elusive. In a porcine polytrauma model including blunt chest trauma, liver laceration, femur fracture and haemorrhage serial trans-thoracic echocardiography was performed and correlated with cellular cardiac injury as well as with the occurrence of extracellular histones in serum. Postmortem analysis of heart tissue was performed 72 h after trauma. Ejection fraction and shortening fraction of the left ventricle were significantly impaired between 4 and 27 h after trauma. H-FABP, troponin I and extracellular histones were elevated early after trauma and returned to baseline after 24 and 48 h, respectively. Furthermore, increased nitrotyrosine and Il-1ß generation and apoptosis were identified in cardiac tissue after trauma. Main structural findings revealed alteration of connexin 43 (Cx43) and co-translocation of Cx43 and zonula occludens 1 to the cytosol, reduction of α-actinin and increase of desmin in cardiomyocytes after trauma. The cellular and subcellular events demonstrated in this report may for the first time explain molecular mechanisms associated with cardiac dysfunction after multiple trauma.

Complement C5a-Induced Changes in Neutrophil Morphology During Inflammation.

The complement and neutrophil defence systems, as major components of innate immunity, are activated during inflammation and infection. For neutrophil migration to the inflamed region, we hypothesized that the complement activation product C5a induces significant changes in cellular morphology before chemotaxis. Exposure of human neutrophils to C5a dose- and time-dependently resulted in a rapid C5a receptor-1 (C5aR1)-dependent shape change, indicated by enhanced flow cytometric forward-scatter area values. Similar changes were observed after incubation with zymosan-activated serum and in blood neutrophils during murine sepsis, but not in mice lacking the C5aR1. In human neutrophils, Amnis high-resolution digital imaging revealed a C5a-induced decrease in circularity and increase in the cellular length/width ratio. Biomechanically, microfluidic optical stretching experiments indicated significantly increased neutrophil deformability early after C5a stimulation. The C5a-induced shape changes were inhibited by pharmacological blockade of either the Cl-/HCO3--exchanger or the Cl- -channel. Furthermore, actin polymerization assays revealed that C5a exposure resulted in a significant polarization of the neutrophils. The functional polarization process triggered by ATP-P2X/Y-purinoceptor interaction was also involved in the C5a-induced shape changes, because pretreatment with suramin blocked not only the shape changes but also the subsequent C5a-dependent chemotactic activity. In conclusion, the data suggest that the anaphylatoxin C5a regulates basic neutrophil cell processes by increasing the membrane elasticity and cell size as a consequence of actin-cytoskeleton polymerization and reorganization, transforming the neutrophil into a migratory cell able to invade the inflammatory site and subsequently clear pathogens and molecular debris.

Quantitative and qualitative analysis of student tutors as near-peer teachers in the gross anatomy course.

INTRODUCTION: Peer teaching is a well-established teaching method in medical education. During the 2012/13 winter term, the Institute of Anatomy and Cell Biology in Ulm, Germany, introduced a longitudinal didactics program ("Train the Tutor": TtT) to train student tutors as near-peer teachers (NPT) in the dissection course (DC). Twenty-three of 38 tutors participated in the programme. Our study describes the educational concept and the NPTs' activities in the dissection course. METHODS: NPTs documented their activities on a daily basis in the form of semi-structured reports. A total of 575 reports were quantitatively and qualitatively analysed. Free-text analysis was performed using Grounded Theory followed by code quantification of all indications (n=1868). RESULTS: NPTs spend 61% of their time dissecting by themselves or supervising the tutee's dissection process. Organisational tasks had a larger share at the beginning of the course. Just before examinations the proportion of time spent giving feedback rose. Of all positive indications, 45% described experiences working with the tutees. In contrast, 68% of all negative indications were characterized by a self-critical reflection on their own activities. NPTs included all learning domains in their teaching, substantially functioning as teachers and role models to convey particular attitudes. CONCLUSION: TtT-Trained Tutors (NPT) clearly met the requirements of a practical course and adjusted their activities in response to the course's progress. NPTs were concerned about their tutees' attitudes and may need more professional support within the TtT program regarding this.

[The Ulm trauma track : Trauma care and research as focal points for medical students]. / Der Ulmer Trauma-Track : Traumaversorgung und -forschung als Schwerpunktsetzung im Medizinstudium.

BACKGROUNDS AND OBJECTIVES: As part of the expansion of the site-specific education profile of the medical curriculum MED@ULM of the University of Ulm, a new track "trauma care and trauma research" was established in the winter semester 2012/2013. The acceptance of the track was evaluated during the winter semester 2013/2014. MATERIAL AND METHODS: The 6-semester track extends the existing curriculum by offering subjects in trauma management and trauma research to students of human medicine. A central aim of the track is to promote medical professional competence, expertise in emergency care and competence in trauma-related scientific work and research. Central learning contents could be intensified in newly established emergency simulation training. Additionally, participating students have to perform a doctoral thesis on an obligatory trauma-related experimental subject. A first analysis study focusing on the learning style of the participating students (n = 17) and a control group consisting of members of the same semester (n = 20) was performed using the Kolb learning style inventory. In a validated evaluation in the winter semesters 2013/2014 and 2014/2015, the students were asked about their expectations and experience with the track, criticisms, suggestions and satisfaction with the study conditions. The data were analyzed using descriptive statistics. RESULTS: The analysis of the students' preferred learning styles revealed no differences between track students and the control group. Most of the students considered the track as a form of personal further education. The students had high expectations of practical skills with relevance to the clinical daily routine, learning scientific methods and preparing their thesis. The track students were more critical with regard to the study conditions than the control group students, although the track students of the third semester still judged their studies to be more interesting than the track students of the first semester and the control group. CONCLUSION: With the introduction of the new trauma track into the curriculum of the medical curriculum MED@ULM of the University of Ulm, a further possibility for medical students to focus on their own individual options was established. At least half of the track students wanted to be later active in the triad of patient care, teaching and research. Further investigations are necessary to determine whether the establishment of the trauma track has a positive influence on the number of new recruits in trauma surgery and anesthesiology.

Characterization of blunt chest trauma in a long-term porcine model of severe multiple trauma.

Chest trauma has a significant relevance on outcome after severe trauma. Clinically, impaired lung function typically occurs within 72 hours after trauma. However, the underlying pathophysiological mechanisms are still not fully elucidated. Therefore, we aimed to establish an experimental long-term model to investigate physiological, morphologic and inflammatory changes, after severe trauma. Male pigs (sus scrofa) sustained severe trauma (including unilateral chest trauma, femur fracture, liver laceration and hemorrhagic shock). Additionally, non-injured animals served as sham controls. Chest trauma resulted in severe lung damage on both CT and histological analyses. Furthermore, severe inflammation with a systemic increase of IL-6 (p = 0.0305) and a local increase of IL-8 in BAL (p = 0.0009) was observed. The pO2/FiO2 ratio in trauma animals decreased over the observation period (p < 0.0001) but not in the sham group (p = 0.2967). Electrical Impedance Tomography (EIT) revealed differences between the traumatized and healthy lung (p < 0.0001). In conclusion, a clinically relevant, long-term model of blunt chest trauma with concomitant injuries has been developed. This reproducible model allows to examine local and systemic consequences of trauma and is valid for investigation of potential diagnostic or therapeutic options. In this context, EIT might represent a radiation-free method for bedside diagnostics.

The crucial role of neutrophil granulocytes in bone fracture healing.

Delayed bone fracture healing and the formation of non-unions represent an important clinical problem, particularly in polytrauma patients who suffer from posttraumatic systemic inflammation. However, the underlying pathomechanisms remain unclear. Neutrophil granulocytes are crucial effector cells in the systemic immune response and represent the most abundant immune cell population in the early fracture haematoma. Here we investigated the role of neutrophils in a mouse model of uncomplicated fracture healing and compromised fracture healing induced by an additional thoracic trauma. Twenty four hours before injury, 50 % of the mice were systemically treated with an anti-Ly-6G-antibody to reduce neutrophil numbers. In the isolated fracture model, Ly-6G-Ab treatment significantly increased the concentration of both pro- and anti-inflammatory cytokines, including interleukin (IL)-6 and IL-10, and chemokines, for example, C-X-C motif ligand 1 (CXCL1) and monocyte chemotactic protein-1 (MCP-1), in the fracture haematoma. Monocyte/macrophage recruitment was also significantly enhanced. After 21 d, bone regeneration was considerably impaired as demonstrated by significantly diminished bone content and impaired mechanical properties of the fracture callus. These results indicate that undisturbed neutrophil recruitment and function in the inflammatory phase after fracture is crucial to initiate downstream responses leading to bone regeneration. In the combined trauma model, the reduction of neutrophil numbers ameliorated pulmonary inflammation but did not provoke any significant effect on bone regeneration, suggesting that neutrophils may not play a crucial pathomechanistic role in compromised fracture healing induced by an additional thoracic trauma.

Effect of didactically qualified student tutors on their tutees' academic performance and tutor evaluation in the gross anatomy course.

INTRODUCTION: Peer teaching is widely applied in medical education, anatomists having a notably long tradition in cooperating with student tutors in the dissection course. At Ulm University we established an intensified concomitant didactic training program for student tutors and investigated possible effects on their tutees' academic performance and tutor evaluation. METHODS: In winter semester 2012/13 all student tutors of the dissection course were invited to participate in the "Train-the-Tutor" educational program.1 Test results and failure rates of 149 tutees who had been supervised by program participants (n=14) and 136 tutees of not participating tutors (n=13) were analyzed, as well as data on tutor evaluation and learning behavior of 235 (82%) of these tutees. RESULTS: Overall, both groups of tutees showed equal learning behavior and evaluated their tutors' performances similarly. However, tutees of program participants consistently obtained better examination results (median: 1.9 versus 2.2 in overall scores) and lower ultimate failure rates (13.4 versus 17.6% of students failed, respectively). DISCUSSION: An intensified didactic training program for student tutors may help their tutees to pass the gross anatomy course. Additional studies are necessary to objectify and further investigate this effect in order to optimize the concept regarding time expenditure and costs.

The lectin complement pathway serine proteases (MASPs) represent a possible crossroad between the coagulation and complement systems in thromboinflammation.

UNLABELLED: ESSENTIALS: The lectin pathway's MASP-1/2 activates coagulation factors but the trigger of the activation is unknown. MASP-1/2 activation was assessed by quantifying complexes between MASPs and antithrombin/C1-inhibitor. Activated platelets and fibrin were demonstrated to activate MASP-1 and MASP-2 both in vitro and in vivo. These findings may represent a crossroad between the complement and the coagulation systems. BACKGROUND: The activated forms of the complement lectin pathway (LP) proteases MASP-1 and MASP-2 are able to cleave the coagulation factors prothrombin, fibrinogen, factor XIII and thrombin-activatable fibrinolysis inhibitor in vitro. In vivo studies also show that MASP-1 is involved in thrombogenesis. OBJECTIVES: To clarify the not yet identified mechanisms involved in triggering activation of the LP during thrombotic reactions. METHODS: Novel sandwich-ELISAs for detection of complexes between MASP-1 or MASP-2 and the serpins C1 inhibitor (C1-INH) or antithrombin (AT), were used to specifically detect and quantify the activated forms of MASP-1 and MASP-2. RESULTS: Activated platelets were shown by flow cytometry to bind Ficolin-1, -2 and -3 but not MBL, which was associated with activation of MASP-1 and MASP-2. We also demonstrated that fibrin and the plasmin-generated fibrin fragment DD in plasma, bind and activate MASP-1 and MASP-2. As demonstrated by the ELISA and SDS-PAGE/Western blotting, the fibrin-associated activation was reflected in a specific inactivation by AT during clotting without the assistance of heparin. In all other cases the MASPs were, as previously reported, inactivated by C1-INH. In systemic lupus erythematosus patients with thrombotic disease and in polytrauma patients, the levels of activated MASP-1 and MASP-2 in complex with both AT and C1-INH were associated with markers of thrombotic disease and contact/coagulation system activation. CONCLUSIONS: MASP-1 and MASP-2 are activated during blood clotting. This activation is triggered by activated platelets and by the generation of fibrin during thrombotic reactions in vitro and in vivo, and may represent a novel activation/amplification mechanism in thromboinflammation.

Damage- and pathogen-associated molecular patterns and alarmins: keys to sepsis?.

The concept that sepsis is the result of an uncontrolled inflammatory response of the host's innate immune system towards invading pathogens has recently been challenged. Evidence is accumulating that, in addition, host-derived alarm molecules are released during sepsis- and trauma-associated cell death, thus triggering the host's immune response. The identification and characterization of exogenous as well as endogenous danger molecules allowed significant advances in our understanding of the pathophysiology of sepsis and may provide potential targets for therapeutic interventions.

The influence of coagulation and inflammation research on the improvement of polytrauma care.

Treatment guidelines and management principles of polytrauma patients are largely derived from experience, supplemented by the results of few clinical studies. Their clinical impact on survival outcome is rarely scientifically evaluated. Hence, research algorithms need to be developed which enable a rapid and profound reevaluation of the current treatment strategies in polytrauma care and which provide a solid basis for the assessment of future treatment options. Such new concepts might include a more individualized approach and a better identification of operative windows for early definitive care. Since polytrauma results in a complex physiological and immunological disorder, which is additionally influenced by multiple confounding variables, it is challenging to establish such novel algorithms by clinical research only. In this regard, the well defined parameters in valid basic science models can provide a solid base for evaluating current concepts and investigating future treatment options. Here we have analyzed the contribution of basic science to well-established concepts in polytrauma care, such as the management of trauma induced coagulopathy or the damage control orthopedics concept. Many of these ideas moved from previous basic science activities to clinical studies but in many cases the direct effects of basic science on clinical trials or even clinical management strategies often remain elusive. Nevertheless, the knowledge which is created on a daily basis by basic science studies acts as an invaluable data pool, which can be accessed and combined for the clinical researcher to develop and address clinically relevant questions, providing them with a comprehensive pool of information to carefully plan and conduct their clinical trials. This may then subsequently lead to the development of new management principles for polytrauma patients.

[Trauma research net of the German Society for Orthopaedics and Trauma Surgery]. / Netzwerk Traumaforschung der Deutschen Gesellschaft für Orthopädie und Unfallchirurgie.

A first meeting of the recently founded "Trauma Research Net" of the German Society for Orthopaedics and Trauma Surgery (DGOU e.V.) took place at the Reisensburg Castle, Günzburg, from 24 to 26 February 2011. Numerous representatives of trauma-related Research Institutes and University Hospitals in Germany demonstrated their main research foci. There was also an open discussion of current problems in trauma research, especially the lack of junior researchers and nationwide collaborations as well as limited information about the research topics of individual research groups. The overall research efforts of the "Trauma Research Net" apparently focus on fracture, multiple injury and inflammation on an organ and cellular level. Furthermore, an up-to-date matrix of the existing methods has been generated which is now provided for the networker. The common middle-term goal of the "Trauma Research Net" is the inclusive, intensive scientific exchange as well as the generation and workup of common hypotheses using standard operating procedures. In the long term, the resulting clustered research activities are intended to address and resolve clinically relevant questions in the field of trauma research.

[Surgical treatment of ankle fractures as an outpatient procedure. A safe and resource-efficient concept?]. / Ambulante Versorgung operativer Spunggelenkfrakturen an einem US-Traumazentrum. Ein valides Modell im DRG-Zeitalter?

BACKGROUND: In many European countries, patients requiring surgical treatment of ankle fractures are generally hospitalized for an average of 8-11 days. This anecdotal concept is largely based on the premise that the inpatient monitoring of soft tissue conditions may lead to a decreased complication rate. The present study was designed to test the hypothesis that the surgical care of isolated ankle fractures as an outpatient procedure represents a safe and feasible concept which is not associated with an increased complication rate. METHODS: A retrospective analysis was performed of a prospective database during a 5-year period (01/01/2005-12/31/2009) at a US academic level 1 trauma center with an institutional protocol of outpatient surgery for isolated ankle fractures. All fractures were classified according to the AO/OTA system. Outcome parameters consisted of the rate of postoperative complications and frequency of unplanned surgical revisions outpatient isolated versus inpatient isolated with surgical fixation of ankle isolated fractures. RESULTS: Among 810 consecutive patients with ankle fractures during the study period, 476 met the inclusion criteria. Of these, 256 patients (53.8%) were treated as outpatients. The average length of stay of patients who were admitted as inpatients was 1.5±0.8 days (range 1-5 days). The age distribution was in a similar range for inpatients and outpatients (39±14.1 vs 35±12.8 years), and the injury severity based on the AO/OTA fracture classification revealed a similar distribution of fracture patterns in both groups. The rate of postoperative complications (9.1 vs 3.1%) and of unplanned surgical revisions (3.6 vs 1.2%) was significantly increased in the hospitalized group, compared to patients with ambulatory surgery (P<0.05). CONCLUSION: The surgical treatment of isolated ankle fractures as an outpatient procedure represents a safe and resource-efficient concept which is not associated with an increased complication rate. Cultural differences in the domestic environment of individual patients may have to be taken into consideration.

[Evaluation of an objective structured clinical examination (OSCE) in surgery and orthopedics by medical students]. / Studentische Evaluation einer objektiven, strukturierten klinischen Prüfungsmethode (OSCE) im Fach Chirurgie und Orthopädie.

BACKGROUND: The objective structured clinical exam (OSCE) has become an established form of examination. However, for general and orthopedic surgery it has barely been evaluated. Therefore, the present study was performed to analyze the OSCE in surgery by the students of the University of Ulm. MATERIAL AND METHODS: In total 304 medical students undertaking the OSCE were included in the study. The students were asked to fill out a standardized questionnaire which contained different evaluation parameters, such as test adequacy, comprehensibility, balance, difficulty, atmosphere and clinical relevance as well as self-assessment and overall rating. RESULTS: In the overall rating the OSCE was rated as having a clinical relevance. The preferred preparation strategies were the clinical traineeship and standard medical textbooks. Altogether, the OSCE was chosen as the preferred future examination method, followed by multiple choice testing and clinical practical examination. CONCLUSION: The evaluation of the OSCE by the medical students at the University of Ulm showed a high acceptance rate as well as a high clinical relevance.

Non-resorbing osteoclasts induce migration and osteogenic differentiation of mesenchymal stem cells.

Osteoclast activity has traditionally been regarded as restricted to bone resorption but there is some evidence that also non-resorbing osteoclasts might influence osteoblast activity. The aim of the present study was to further investigate the hypothesis of an anabolic function of non-resorbing osteoclasts by investigating their capability to recruit mesenchymal stem cells (MSC) and to provoke their differentiation toward the osteogenic lineage. Bone-marrow-derived human MSC were exposed to conditioned media (CM) derived from non-resorbing osteoclast cultures, which were generated from human peripheral blood monocytes. Osteogenic marker genes (transcription factor Runx2, bone sialoprotein, alkaline phosphatase (AP), and osteopontin) were significantly increased. Osteogenic differentiation (OD) was also proved by von Kossa and AP staining occurred in the same range as in MSC cultures stimulated with osteogenic supplements. Chemotactic responses of MSC were measured with a modified Boyden chamber assay. CM from osteoclast cultures induced a strong migratory response in MSC, which was greatly reduced in the presence of an anti-human platelet-derived growth factor (PDGF) receptor beta antibody. Correspondingly, significantly increased PDGF-BB concentrations were measured in the CM using a PDGF-BB immunoassay. CM derived from mononuclear cell cultures did not provoke MSC differentiation and had a significantly lower migratory effect on MSC suggesting that the effects were specifically mediated by osteoclasts. In conclusion, it can be suggested that human non-resorbing osteoclasts induce migration and OD of MSC. While effects on MSC migration might be mainly due to PDGF-BB, the factors inducing OD remain to be elucidated.

Polytrauma--pathophysiology and management principles.

BACKGROUND: Multiple injury results in a complex pathophysiological and immunological response. Depending on the individual injury pattern, the time elapsed after injury, and the systemic "danger response", the surgical treatment has to be modified. OBJECTIVES: This overview provides new insights in the pathophysiology of the early danger response after polytrauma and outlines the main resulting consequences for surgical management. RESULTS: First, synchronically to the clinical assessment, life-saving procedures need to be performed rapidly, such as control of massive intra-thoracic or abdominal bleeding and decompression of the chest and brain, as standardized by advanced trauma life support guidelines. During the second phase of "day-one-surgery" damage-control interventions such as debridement, decompression and temporary fracture stabilization are needed to avoid an excessive molecular and cellular danger response. Trauma-adjusted surgical techniques are crucial to limit the systemic response known to put remote organs at risk. In the "vulnerable phase" when the patient's defense is rather uncontrolled, only "second look" debridement to minimize a "second hit" is recommended. After stabilization of the patient as indicated by improvement of tissue oxygenation, coagulation, and decreased inflammatory mediators, "reconstructive surgery" can be applied. CONCLUSION: Individually adjusted surgical "damage control" and "immune control" are important interactive concepts in polytrauma management.