Systemische Freisetzung von Prostanoiden nach chirurgisch induzierter Verletzung des Lungengewebes

In a prospective study, the systemic inflammatory consequences of surgery-induced lung tissue injury were evaluated using biochemical markers. The aim was to examine whether this type of injury produces a specific pattern of prostanoid plasma levels (prostacyclin, thromboxane, PGE₂, PGF_2α, and PGM). We, therefore, compared 18 patients (group 1) who underwent thoracotomy without injury to the lung with 26 patients (group 2) that had a resection of pulmonary tissue due to benign diseases. Group 2 patients clearly revealed increased plasma levels of C-reactive protein as well as of the granulocyte-specific PMN-elastase. In particular, there was a pronounced release of prostacyclin and its antagonist thromboxane A₂ following lung tissue resection. In contrast to group 1 patients, lung tissue damage resulted in immediately elevated plasma levels of PGF_2α and PGE₂. When, however, taking into account the time course of PGM, the stable cleavage product of PGF_2α, there was no hint of an altered pulmonary metabolic capacity. Presumably, this pattern of elevated prostanoid levels in group 2 is the result of the surgical damage to the lung tissue. Therefore, it can be suggested to be specific for that type of injury. Thus, the release of prostanoids following surgery-induced lung tissue damage may indicate the importance of these mediators, particularly in thoracic injuries associated with lung damage since those may lead to post-traumatic pulmonary dysfunction. These substances may also be useful in evaluating both the severity and the extent of lung tissue damage following major trauma.     

Humerus reconstruction after gunshot fracture]

High-velocity bullits can cause severe blast injuries with shattering and defects of the large bones. Initial external fixation is followed by rebuilding of the bone, which is difficult due to concomitant infection, poor revascularization and lack of a suitable bone bed. A case report of an injured African soldier shows the follow-up and difficulties of reconstruction of the shattered humerus by repeated spongious bone grafting. After successful remodeling of the bone, external fixation is followed by ASIF dynamic compression-plate osteosynthesis.     

Influence of stress simulation parameters on the fracture strength of all-ceramic fixed-partial dentures.

OBJECTIVES: This in vitro study tested the influence of diverse stress simulation parameters on the fracture strength of all-ceramic three-unit fixed partial dentures (FPDs). METHODS: All-ceramic FPDs made of Empress 2 (Ivoclar-Vivadent, FL) were exposed to thermal cycling and mechanical loading (TCML) with varying loading parameters such as chewing force (amount, frequency), thermal loading, lateral jaw motion, abutment material, artificial periodontium or antagonistic denture. To investigate the influence of the abutment material, human teeth, polymer abutments and alloy abutments were used. Two different TCML devices with pneumatic or weight loading were compared. FPDs without aging were used as a control. RESULTS AND SIGNIFICANCE: Combined thermal and mechanical loading significantly reduced the FPD fracture resistance from 1832N to 410N. Duplication of chewing frequency, phase load increase or additional lateral movement did not effect the results. Increasing chewing force, artificial periodontium, and antagonist or abutment material reduced the fracture resistance of the tested FPDs. Different devices with weight or pneumatic loading had no significant influence on the loading capacity of the FPDs. Artificial aging should be performed combining thermal cycling with mechanical loading. Simulation of the artificial periodontium, human antagonists and abutments should be included to achieve a significant aging.     

Distinct effects of surgical denervation on hepatic perfusion, bowel ischemia, and oxidative stress in brain dead and living donor porcine models.

The liver function and perfusion following brain death is mainly influenced by the sympathetic nerves and hormones. We examined the specific influence of surgical liver denervation on systemic and hepatic perfusion parameters, bowel ischemia and oxidative stress in hemodynamically stable BD and control (living donor [LD]) pigs. Brain death was induced in 8 pigs via saline infusion into the balloon of an epidural Tieman-catheter (1 mL/15 minutes) and compared to the control group (n = 6) over 4 hours. At 2 hours postoperatively, complete liver denervation was initiated. We analyzed systemic cardiocirculatory parameters (mean arterial pressure, aortic flow, bowel ischemia (endotoxin, and endotoxin-neutralizing capacity) and oxidative stress (total glutathione in erythrocytes [tGSH(E)]) and compared them to local/hepatic perfusion parameters (hepatic artery and portal venous flow, liver blood flow index, and microperfusion), local bowel ischemia (intramucosal pH [pHi] of stomach [pHi(S)]/colon[pHi(C)]), and liver oxidative stress (glutathione [rGSH(L), GSSG(L)]). Following brain death, the parameters including mean arterial pressure, aortic flow, pHi, endotoxin, and tGSH(E) showed no significant changes at 2 hours. Portal venous flow and microperfusion were decreased significantly and hepatic arterial buffer response was ineffective. Hepatic oxidative stress was increased in BD animals (decrease rGSH(L), increase GSSG(L)). Surgical denervation/manipulation increased portal venous flow significantly, hepatic arterial buffer response became effective, and stomach pHi decreased (BD and LD groups). Hepatic oxidative stress was reduced in the BD group (increase rGSH(L)/GSSG(L); P < 0.001) while it was increased in the LD group (decrease rGSH(L)/GSSG(L); P < 0.001). In conclusion, denervation reduces hepatic oxidative stress in BD only in contrast to the LD. The reciprocal effect of denervation depends on the state of neural activation and postulates a potential benefit of surgical denervation before organ harvesting in brain death.     

Komplikationen navigierter Eingriffe an der Wirbelsäule

Both 2D and 3D computer navigation systems have become important tools in the operative treatment of spinal injuries. 2D navigation utilizes a modality-based dataset from the C-arm, while 3D-navigation is based on a non-modality-based dataset from conventional computed tomography or on 3D modality-based ascertainment of data by an isocentric C-arm equipped with an appropriate computer. Experimental and clinical studies have shown increasing accuracy of transpedicular screw placement with all types of computer navigation than with traditional implantation, but unsatisfactory levels of precision are still recorded even when computer navigation is used. Before computer navigation systems can be used with sufficient precision it is necessary to know the potential sources of error for each of the various modalities. These extend from the data acquisition through data transfer and preparation of the dataset for use in computer navigation to intraoperative use of each navigation system. Those who are starting to use such systems must undergo a specialized course of instruction followed by supervised training, and any surgeon who applies them must be sufficiently experienced and well informed to be able to view them with a well-founded criticism; only then are identification and consequent avoidance of complications of computer navigation possible.     

Local tissue properties in bone healing: Influence of size and stability of the osteotomy gap

To characterize the site-specific mechanical and histological properties in fracture repair and to relate these properties to the initial mechanical situation, an experimental fracture model was used in the metatarsus of 42 sheep. the mechanical situation of a transverse osteotomy was described by three gap sizes (1,2, or 6 mm) and two amounts of strain (7 or 31 %). An external fixator that allowed a defined axial movement provided control of these settings. Nine weeks following surgery, the healing area was dissected and tensile and compressive properties were measured in subregions of the fracture gap and the periosteal callus. The central, sagittal section was used for quantitative histology. We found the quality of the tissue along the osteotomy line to be most important for regaining mechanical stability. Increasing the size of osteotomy gaps resulted in poorer mechanical and histological qualities, and the repair process was less complete. Interfragmentary strain did not significantly influence the repair process. The smaller strain levels had already stimulated the secondary repair process, and this stimulatory effect could not be further enhanced by increasing the amount of strain. Our finding that large gaps between bone segments were not as well healed as were smaller gaps suggests that it is advantageous to avoid large gaps in fracture treatment.     

Coxsackievirus B3-Induced Myocarditis : Perforin Exacerbates Disease, But Plays No Detectable Role in Virus Clearance

Viral myocarditis is remarkably common, being detected in approximately 1% of unselected asymptomatic individuals. Many cases are attributable to enteroviral infection, and in particular to coxsackievirus B3. The underlying pathogenesis is controversial, but most studies admit the important immunopathological role of infiltrating CD8⁺ (cytotoxic) T lymphocytes (CTLs). We have previously shown that CTLs play conflicting roles in coxsackievirus B (CVB) myocarditis; they assist in controlling virus replication, but also are instrumental in causing the extensive inflammatory disease, which often results in severe myocardial scarring. A role for perforin, the major CTL cytolytic protein, in CVB myocarditis has been suggested, but never proven. In the present study we use perforin knockout (PKO) mice to show that perforin plays a major role in CVB infection; in broad terms, perforin is important in immunopathology, but not in CVB clearance. For example, PKO mice are better able to withstand a normally lethal dose of CVB (100% survival of PKO mice compared with 90% death in +/+ littermates). In addition, PKO mice given a nonlethal dose of CVB develop only a mild myocarditis, whereas their perforin⁺ littermates have extensive myocardial lesions. The myocarditis in PKO mice resolves more quickly, and these mice show minimal histological sequelae; in contrast, late in disease the perforin⁺ mice develop severe myocardial fibrosis. PKO mice, despite lacking this major CTL effector function, can control the infection and eradicate the virus; growth kinetics and peak CVB titers are indistinguishable in PKO and perforin⁺ mice. Therefore, the immunopathological and antiviral effects of CTLs can be uncoupled by ablation of perforin; this offers a promising target for therapy of myocarditis. Furthermore, we evaluate the possible roles of apoptosis, and of chemokine expression, in CVB infection. In perforin⁺ mice, apoptotic cells are detected within the inflammatory infiltrate, whereas in their PKO counterparts, apoptotic myocyte nuclei are seen. Chemokine expression in both PKO and perforin⁺ mice precedes and parallels the course of myocarditis. Several chemokines are detectable earlier in PKO mice than in perforin⁺ mice, but PKO mice show reduced peak levels, and chemokine expression decays sooner. In particular, MIP-1α expression is barely detectable at any time point in PKO mice, but it is readily identified in perforin⁺ animals, peaking just before the time of maximal myocarditis; this is particularly interesting, given that MIP-1α knockout mice are resistant to CVB myocarditis, but remain able to control viral infection. Thus, the chemokine pathway offers a second route of intervention to diminish myocarditis and its sequelae, while permitting the host to eradicate the virus.     

In situ characterization of T lymphocyte subsets in the reactional states of leprosy.

Using monoclonal antibodies and the immunoperoxidase technique, the numbers and distribution of T lymphocyte subsets in the tissues of reactional states of leprosy (six reversal reaction, nine erythema nodosum leprosum (ENL) and two Lucio's reaction) were determined and compared with those found in stable, non-reactional patients (six tuberculoid, two borderline lepromatous and seven lepromatous). The pattern of segregation of the suppressor/cytotoxic phenotype at the periphery of the granuloma was found in both non-reactional tuberculoid lesions and reversal reactions, but was better developed in the former. In ENL and Lucio's reaction, as well as in non-reactional lepromatous tissue, the helper/inducer and suppressor/cytotoxic phenotypes were both admixed with the aggregated histiocytes. However, the helper/suppressor ratio in ENL (2.1 +/- 0.4) was significantly larger than that in non-reactional lepromatous tissue (0.7 +/- 0.4, P less than 0.001). The immature thymocyte antigen OKT6 was found on scattered large non-lymphoid cells, most commonly in tuberculoid and reversal reaction tissues, less commonly in ENL, but only irregularly in non-reactional lepromatous tissue. The peripheral pattern of the suppressor/cytotoxic phenotype may be an immunohistological reflection of a cell-mediated immune response common to both non-reactional tuberculoid and reversal reaction patients. The reversal of the helper/suppressor ratio in ENL as compared to non-reactional lepromatous disease suggests some role for cell-mediated immunity in the pathogenesis of ENL. The OKT6 positive cell is of unknown origin and function.