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Florian Gebhard

Publications and source records attributed to Florian Gebhard.

18 recordsLinked to original sources
PubMed2005

Changes in the novel orphan, C5a receptor (C5L2), during experimental sepsis and sepsis in humans.

Sepsis is associated with extensive complement activation, compromising innate immune defenses, especially in neutrophils (PMN). Recently, a second C5a receptor (C5L2) was detected on PMN without evidence of intracellular signaling. The current study was designed to determine changes in C5L2 in blood PMN during sepsis. In vitro exposure of PMN to C5a, but not to fMLP, led to reduced content of C5L2. Following cecal ligation and puncture-induced sepsis in rats, PMN demonstrated a time-dependent decrease in C5L2. In vivo blockade of C5a during experimental sepsis resulted in preservation of C5L2. Similarly, PMN from patients with progressive sepsis showed significantly reduced C5L2 expression (n = 26), which was virtually abolished in patients who developed multiorgan failure (n = 10). In contrast, sepsis survivors exhibited retention of C5L2 (n = 12/13). The data suggest that C5L2 on PMN diminishes during sepsis due to systemic generation of C5a, which is associated with a poor prognosis.

Amino Acid Sequence↗
PubMed2005

Pulmonary contusion causes impairment of macrophage and lymphocyte immune functions and increases mortality associated with a subsequent septic challenge.

OBJECTIVE AND DESIGN: Pulmonary contusion is frequently followed by acute respiratory distress syndrome, pneumonia, and sepsis. However, immunologic alterations of circulating and resident immune cell populations contributing to the posttraumatic immunosuppression are poorly understood. We therefore characterized the influence of pulmonary contusion on peripheral blood mononuclear cells, peritoneal macrophages, splenocytes, and splenic macrophages. To address the significance of the immunosuppression associated with lung contusion, we investigated how the consecutive addition of moderate or severe sepsis affected survival after blunt chest trauma. SUBJECTS: Male C3H/HeN mice (n = 10 per group) were anesthetized and subjected to chest trauma or sham procedure. MEASUREMENTS: The cytokine release of cultured peripheral blood mononuclear cells, peritoneal macrophages, splenocytes, and splenic macrophages and plasma levels of tumor necrosis factor-alpha and interleukin-6 from those animals were quantified. Sepsis was induced via cecal ligation and puncture 24 hrs after lung contusion. MAIN RESULTS: Two hours after blunt chest trauma, plasma tumor necrosis factor-alpha and interleukin-6 were markedly increased, as was peripheral blood mononuclear cell cytokine production, lung myeloperoxidase activity, and lung chemokine concentrations. At 24 hrs and, in part, already at 2 hrs, cytokine release from peritoneal macrophages, splenic macrophages, and splenocytes was significantly suppressed. Furthermore, pulmonary contusion when followed by moderate sepsis significantly diminished survival rate when compared with chest trauma or moderate sepsis alone. CONCLUSIONS: These results indicate that pulmonary contusion causes severe immunodysfunction of splenocytes, macrophages, and monocytes in different local compartments and systemically. Moreover, this immunosuppression is associated with an increased susceptibility to infectious complications, which results in a decreased survival rate if blunt chest trauma is followed by a septic insult.

Analysis of Variance↗
PubMed2004

Which navigation when?

If a surgeon is considering purchasing a navigation system, several factors have to be evaluated including, the planned applications, the equipment already installed, and the specific knowledge of the surgeon. For use in traumatology, fluoroscopy and more specifically 3-D fluoro-based computer guidance is preferable. These technologies are based on intraoperative acquired arbitrary images in contrast to CT-based techniques, which refer to preoperative acquired images that represent a so called "cannel reality". However, image quality has to be considered as fluoro-picture quality depending on the anatomical area (eg long bones, spine, pelvis) and body mass index. CT-based navigation provides better image quality and accuracy but is not able to visualize reduction processes. Therefore personal experience in courses or by on-site teaching is recommended prior taking the decision.

Fluoroscopy↗
PubMed2004

Navigation at the spine.

Computer aided and computer navigated operative techniques have been used for the first time in neurosurgery and surgery of the spine. For computer aided surgery of the spine there are currently two different methods: CT-based and C-arm based techniques. The advantage of the CT-based technique is its accuracy especially in difficult anatomical regions like the cervical and upper thoracic spine, and the possibility of preoperative planning. The advantage of C-arm navigation is the broad intraoperative availability with the disadvantage of limited image quality in some regions of the spine eg, the upper thoracic spine. This last disadvantage has been dramatically improved by introducing 3-D C-arm navigation (ISO C 3-D, Siemens, GER). Generally, all methods enhance the precision of pedicle screw insertion. Clinical as well as experimental studies show an exact pedicle screw position using the computer navigated techniques in over 90% of cases. C-arm based navigational techniques are being constantly improved and the future will be CT-like images with instant intraoperative availability.

Bone Screws↗
PubMed2004

Computer aided high tibial open wedge osteotomy.

High tibial osteotomy is a widely accepted treatment of medial compartment osteoarthritis as well as other lower extremity deformities. However, it is a technically demanding procedure. The lack of exact intraoperative real time control of the mechanical axis often results in postoperative malalignments, which is one reason for poor long term results. These problems can be addressed with the use of a surgical navigation system. Following exposure, dynamic reference bases (DRBs) are attached to the femur, and the proximal and the distal part of the tibia. After intraoperative measurement of the deformities and correction planning, the osteotomy is performed under navigational guidance. The wedge size, joint line orientation, and tibial plateau slope are monitored during correction. The in vitro evaluation with a plastic bone model suggests that the error of deformity correction is less than 1.7 degrees (95% confidence limits) in the frontal, and less than 2.3 degrees (95% confidence limits) in the sagittal plane, respectively. On a cadaver study of 13 legs, the mechanical axis intersected the Fujisawa line in 80.7% (range 77.5-85.8%). The preliminary clinical experience confirms these results. A novel computer tomography free navigation system for high tibial osteotomy has been developed that holds the promise of improving the accuracy, reliability, and safety of this kind of approach.

Adult↗
PubMed2004

Computer aided reduction and imaging.

Reduction is one of the key procedures in orthopedic trauma surgery and has been acknowledged as one of the conditions for a good outcome in intraarticular and extra-articular fractures. The information available to the surgeon during the reduction maneuver can be divided into visual and tactile information. The optimal implementation of these parameters, combined with the surgeon's individual experience, will significantly affect the results of the operation. Anatomical regions where a limited direct view through the approach is supported by intraoperative imaging are intra-articular fractures of the elbow, forearm, acetabulum, proximal tibia, pilon, and hindfoot, and extra-articular fractures of the spine, pelvis, femur, and tibial shaft. Surgery in these regions is demanding since the approaches limit the visual control of the axes and also the anatomical reduction within the joint. Computer aided orthopedic surgery (CAOS) was introduced to increase the accuracy of selected procedures in orthopedic surgery. One of the most frequently applied applications is pedicle screw insertion in posterior spinal surgery. The current working group has identified computer aided reduction and implant positioning as an unresolved area of CAOS that would be highly relevant to the operative treatment of fractures. The development of tools for computer aided reduction is of major importance and is much desired by the orthopedic community. Such a reduction tool would be a significant step forward in the development of orthopedic trauma care. It would facilitate new procedures and new operations and also help to attain a completely new level with regard to what we can achieve in terms of minimal invasiveness and increased precision. The synergies of the expert group are deployed to develop the required software modules and hardware. Other areas of computer aided orthopedic surgery will certainly benefit from the integration of this technology as well.

Bone Screws↗
PubMed2004

Computer-guidance in percutaneous screw stabilization of the iliosacral joint.

Nine patients with instability and one patient with degeneration of the iliosacral joint were treated surgically. The posterior pelvic ring was stabilized with the assistance of an optoelectronic navigation system. Registration was ensured by using fiducial screws in the iliac crest or by collecting landmarks on the external fixator. Computed tomography scans taken postoperatively provided additional information regarding implant localization in all patients. Accurate placement of 21 of 22 implanted iliosacral screws was observed. Two of the 21 screws touched the wall of the second sacral foramen without perforating the canal. One screw perforated the anterior wall of the sacrum because the navigated guide wire was bent during implantation. The initial results indicate that computer-aided frameless navigation in surgery of the iliosacral joint can facilitate surgical performance during screw stabilization in selected patients. Two important issues must be considered in the clinical application of this technique: first, any relative migration of the iliac and sacral bone structures between computed tomography scans taken preoperatively and intraoperative navigation may result in an intolerable inaccuracy of computer guidance. Second, bending of the guide wire of the tracked power drive, which cannot be accommodated by the navigation system, will lead to misguidance; therefore, only navigated drill sleeves should be used.

Bone Screws↗
PubMed2004

Blunt chest trauma induces delayed splenic immunosuppression.

Severe blunt chest trauma is frequently associated with multiple organ failure and sepsis. Posttraumatic immunosuppression seems to play a major role in their development. However, the immunologic alterations following pulmonary contusion are insufficiently elucidated. Specifically, it remains unknown whether immunocompetent cells located distant from the site of the impact are affected. We therefore aimed to characterize the influence of pulmonary contusion on lymphocytes and splenic macrophages. Male C3H/HeN mice (n = 8-10/group) were anesthetized and subjected to trauma or sham procedure. Blunt chest trauma was induced by a blast wave focused on the thorax. Two or 24 h later, splenocytes and splenic macrophages were isolated and stimulated for 48 h. The cytokine release (IFN-gamma, IL-2, IL-3, IL-10, IL-12, IL-18) from splenocytes as well as from splenic macrophages (TNF-alpha, IL-10, IL-12, IL-18) and plasma levels of TNF-alpha and IL-6 were quantified by ELISA. The results indicate that at 2 h after blunt chest trauma, plasma TNF-alpha and IL-6 were markedly increased. At the same time, no differences in splenocyte cytokine production were detectable. However, at 24 h a significantly depressed cytokine release was observed in trauma animals. Furthermore, splenic macrophages showed a significantly decreased production of TNF-alpha, IL-10, and IL-12 at 24 h and markedly increased release of IL-18 at 2 h after trauma. These results indicate that blunt chest trauma causes severe immunodysfunction of lymphocytes and splenic macrophages. Thus, lung contusion as a localized type of trauma causes dysfunction of immunocompetent cell populations, which are located distant from the site of injury.

Animals↗
PubMed2003

Biochemical characterization of individual injury pattern and injury severity.

BACKGROUND: Estimation of trauma severity currently relies on clinical diagnoses and scoring systems. However, the early estimation of the severity of chest trauma and overall soft tissue trauma (STT) remains insufficient. Traditional trauma scoring systems fail to reflect the individual trauma pattern and severity, neglecting the different outcomes after injuries in different body regions. Therefore, the aim of this prospective study was to detect laboratory markers that may reflect the pattern and extent of individual trauma in the very early phase after injury. PATIENTS AND METHODS: In 107 non-selected trauma patients, blood samples were collected almost immediately and then at short intervals after the trauma. In addition to the biochemical analysis of 20 different mediators viewed as potential trauma markers, the following data were correlated with the laboratory results: injury severity score (ISS), polytrauma score (PTS), Ulmer score HTAPE (trauma pattern specific: head (H), thorax (T), abdomen (A), pelvis (P), extremities (E); 0-3 degrees each), multiple organ failure score (MOF), overall, primary and secondary lethality. RESULTS: ISS and the severity of head injury were clearly higher in non-survivors (n=17) than in survivors (n=90) (median ISS: 35 versus 18; median severity of head injury (H): 3 versus 1). Whereas head injury was correlated with early death ( 3 days post-trauma) was influenced by thoracic trauma (r=0.15) as well as by soft tissue trauma (STT, r=0.12). Of all investigated mediators, interleukin-6 (IL-6) displayed the highest correlations (r=0.66, P<0.00001) with the extent of chest trauma, followed by correlations with PTS, STT, fracture trauma (FT) and ISS during the first hour after trauma. There was no correlation between IL-6 and head injury. The extent of STT was correlated best to IL-8 (r=0.75), IL-6 (r=0.54), and creatine kinase (CK, r=0.49) plasma concentrations. CONCLUSION: In the very early stage after an accident the severity of chest trauma is strongly correlated with the plasma concentration of IL-6, and the extent of overall soft tissue trauma (STT) to plasma concentrations of IL-8, IL-6, and CK.

Adolescent↗
PubMed2003

The pattern of preformed cytokines in tissues frequently affected by blunt trauma.

The aim of this prospective study was to determine the local concentrations of inflammatory mediators in various tissue types frequently affected by trauma to estimate the role of prestored cytokine release by mechanical tissue trauma in the induction of a systemic inflammatory response syndrome. The degree of tissue damage, evaluated by its systemic release of inflammatory mediators, represents an important factor concerning the outcome of trauma patients. Clinical trials indicate that the kind of traumatized tissue influences the cytokine pattern measured in patients blood afterwards. However, the tissue-specific mediator composition underlying this systemic mediator release is rarely elucidated. Upon approval of the local IRB/EC, skin, subcutaneous fat, muscle, cancellous bone, and lung tissue were obtained during standard surgical procedures. The protein-based concentrations of Interleukin (IL)-6, IL-8, IL-10, and IL-12 were determined in tissue homogenates by enzyme-linked immunoabsorbant assay (ELISA; n = 60 samples). Albumin was measured to evaluate the degree of blood contamination of tissue samples. IL-6 and IL-8 were consistently detectable in more than 95% of the tissue specimens. Lung and cancellous bone presented by far the highest concentrations of these cytokines, whereas skin, subcutaneous fat, and muscle showed significantly lower levels. IL-10 was not detectable in 88%; IL-12 could not be measured in 63% of the samples. Cytokine concentrations did not correlate with the amount of albumin measured in tissue specimens. Due to their consistent presence at the tissue level, high systemic concentrations of IL-6 and IL-8 in patients blood, seen after pulmonary trauma, long bone fractures, or soft tissue injury, may be interpreted as an overspill of local trauma mediators. This indicates their relevance in post-traumatic monitoring. Furthermore, albumin is a suitable and necessary indicator to evaluate influences of possible blood contamination in tissue samples.

Adipose Tissue↗
PubMed2003

Cardiopulmonary, histological, and inflammatory alterations after lung contusion in a novel mouse model of blunt chest trauma.

Severe blunt chest trauma remains an important injury with high morbidity and mortality. However, the associated immunological alterations are poorly understood. Existing big animal models require large-scale settings, are often too expensive, and research products for immunological studies are limited. In this study we aimed to establish a new model of blunt, isolated and bilateral chest trauma in mice and to characterize its effects on physiological and inflammatory variables. Male C3H/HeN mice (n = 9-10/group) were anesthetized and a femoral artery was catheterized. The animals were subjected to trauma or sham procedure and monitored for 180 min. Blunt chest trauma was induced by a blast wave focused on the thorax. Trauma intensity was optimized by varying the exposure distance. Blood pressure, heart rate, respiratory rate, arterial blood gases and plasma cytokine levels were measured. Macroscopic and microscopic examinations were performed. In addition, outcome was evaluated in a 10-day survival study. Chest trauma caused a drop (P < 0.05) in blood pressure and heart rate, which partly recovered. Blood gases revealed hypoxemia and hypercarbia (P < 0.05) 180 min after trauma. There was marked damage to the lungs but none to abdominal organs. Histologically, the characteristic signs of a bilateral lung contusion with alveolar and intrabronchial hemorrhage were found. Plasma interleukin-6 and tumor necrosis factor alpha were considerably increased after 180 min. Blunt chest trauma resulted in an early mortality of 10% without subsequent death. On the basis of these findings, this novel mouse model of blunt chest trauma appears suitable for detailed studies on immunological effects of lung contusion.

Animals↗
PubMed2003

Induction of apoptosis following blunt chest trauma.

The cause for the high morbidity of blunt chest trauma is not fully understood. It is still unclear if and to what extent a second insult, e.g., apoptotic tissue damage initiated by the primary insult itself, may contribute to the development of serious complications. This study was done to elucidate whether a pulmonary contusion may induce programmed cell death. Sixty-four Wistar rats were evenly randomized to eight experimental groups: four sets were subjected to a standardized blast wave injury and sacrificed 6, 24, 48, and 72 h after the trauma; four groups served as controls for the same time points. Lung and liver samples were stained (H & E; TUNEL), and PMN infiltration was determined by myeloperoxidase (MPO) activity. Caspase 8 was analyzed by Western blot, and TNF-alpha plasma levels by ELISA. Postmortem examination revealed bilateral pulmonary contusion in trauma animals with higher (P < 0.05) numbers of apoptotic cells in lung but not in liver tissue as early as 6 h after the injury. This amount gradually increased and reached a maximum after 48 h: 6.8 +/- 1.1 apoptotic cells/hpf vs. 0.6 +/- 0.06 in controls. Chest trauma caused an increased expression of active caspase 8 in lung but not in liver tissue at 48 and 72 h. TNF-alpha plasma levels were not different. MPO activity in lung tissue of trauma animals increased (P < 0.05) after 6 h and peaked at 72 h. This study has provided the first evidence that apoptotic cell death in lung tissue is initiated following (experimental) pulmonary contusion. The exact mechanism remains, however, unclear and has to be elucidated further.

Animals↗
PubMed2002

Spinal navigation in tumor surgery of the thoracic spine: first clinical results.

In this clinical study, the accuracy of computed tomography-based and computer-guided decompression and insertion of pedicle screws in patients who have had tumor-related posterior surgery of the thoracic spine was evaluated. Eight patients with advanced metastatic disease were treated surgically using a posterior approach with the assistance of an optoelectronic navigation system. Postoperative computed tomography scans were obtained for all patients and provided information regarding decompression and transpedicle implant localization. In all eight patients accurate decompression of the spinal canal was seen. Using the navigation system, 22 of 26 scheduled transpedicle screws were inserted using computer guidance. Eighty-six percent (19 of 22) of the navigated pedicle screws were positioned centrally in the bone. Initial results indicate that computer-aided frameless navigation in tumor surgery of the thoracic spine is a safe system to improve surgical performance during posterior decompression and transpedicle stabilization. Although computed tomography-based computer-assisted spinal navigation is important, the system is not 100% accurate. Therefore, application of the navigation system should be restricted to experienced surgeons who can continue the operation using a conventional approach. Finally, detailed knowledge of the principles of the tracking systems is necessary to prevent possible misinterpretation of information provided by the computer.

Bone Screws↗
PubMed2002

Chemokine activation within 24 hours after blunt accident trauma.

Chemokines mediate the migration of leukocytes to sites of inflammation. Changes in the plasma concentration of interleukin (IL)-8 and macrophage inflammatory protein (MIP)-1beta have not been investigated in the very early phase starting immediately after unintentional trauma. Enrolled in the study were 94 patients with multiple blunt injuries. Blood samples were collected at the scene of accident, then at regular intervals for 24 h. IL-8 and MIP-1beta plasma levels were determined by commercial test kits. Patients were grouped according to trauma severity, pattern of injury, as well as survivors vs. nonsurvivors. Serious casualties [Injury Severity Score (ISS) > or = 32] revealed a significant increase in IL-8 compared to only a slight elevation in individuals with an ISS < 32. Nonsurvivors showed a highly significant (P < 0.005) increase in IL-8 levels beginning immediately after admission. Trauma resulted in a modest activation of MIP-1beta production without differences regarding trauma severity, pattern of injury, or survival. A very strong trauma stimulus is necessary to activate IL-8 production. In contrast to MIP-1beta, IL-8 levels were significantly elevated in nonsurvivors compared to survivors. Therefore, IL-8 might be an early predictor of survival.

Accidents↗
PubMed2002

Pancreatic injury in severe trauma: early diagnosis and therapy improve the outcome.

BACKGROUND: Pancreatic injury is a dangerous complication in multiple injury, and experience with its diagnosis and treatment is usually limited. METHOD: Retrospective analysis of 3,840 patients admitted after multiple trauma from January 1, 1982, until May 31, 2000. RESULTS: A laparotomy was performed in 121 cases (3.15%) due to suspected intra-abdominal lesion. 32% of the patients (39/121) had a pancreatic lesion; 23% (9/39) had a rupture of the major pancreatic duct. Primary laparotomy was performed in 72% of the patients (28/39). Superficial lesions were treated by explorative laparotomy alone (n = 7), debridement and external drainage (n = 20), or necrosectomy and lavage (n = 3). Complex pancreatic lesions were treated by pancreatojejunostomies (n = 5), pancreatic left resections (n = 2), or exploration alone (n = 2). 8 of 39 patients died (20%), 4 intraoperatively. Of the surviving 35 patients, a pancreas-associated complication developed in 8 patients (23%): pancreatic abscesses (n = 4), traumatic pancreatitis (n = 3), pancreatic fistulas (n = 2), and pseudocysts (n = 2). CONCLUSIONS: Pancreatic injury is an infrequent but dangerous complication in severe trauma. Superficial lesions not affecting the major pancreatic duct can be managed by debridement and external drainage. If the major pancreatic duct is ruptured, organ-preserving, complex reconstructive procedures are necessary. When diagnosed timely and treated according to severity and overall situation, pancreatic injuries have an acceptable morbidity, but usually a high mortality.

Abdominal Injuries↗
PubMed2002

Ultrasound, a new tool for surface matching in computer-navigated surgery.

OBJECTIVE: The object of this study was to investigate the feasibility of generating a bone surface from data provided by an ultrasound examination and to match this surface with the previous computed tomography (CT) scan. METHODS: From a CT data set of a training model of the pelvis, a three-dimensional surface was extracted by global thresholding-based segmentation. The same model was placed in a water basin, and ultrasound images were taken with a guided ultrasound transducer. The three-dimensional surface was generated from the ultrasound data set, and the two surfaces were matched in a semiautomatic mode. RESULTS: With special segmentation methods, a surface could be extracted automatically from the CT and the ultrasound data set. From these segmented ultrasound slices, a volume data set of the model was generated. After approximate initial matching, the local matching process was completed automatically. CONCLUSION: One of the limitations in computer-assisted surgery is the complicated matching process. Using special algorithms, a surface was extracted from the data set of an ultrasound examination and matched in a semiautomatic mode with the surface of a CT data set, facilitating the matching process.

Algorithms↗