Die infizierte Gelenkendoprothese

Trauma und Berufskrankheit - Als schwerste Komplikation der Gelenkendoprothetik bleibt die periprothetische Infektion eine Herausforderung—heutzutage nicht nur für den Chirurgen, sondern...     

Effects of voluntary exercise on synaptic plasticity and gene expression in the dentate gyrus of adult male Sprague-Dawley rats in vivo

We have previously shown that voluntary exercise produces enhanced neurogenesis and long-term potentiation (LTP) in the dentate gyrus (DG) of mice in vitro. In the present experiments we show that rats given access to a running wheel (Runners) exhibit significantly more short-term potentiation and LTP with theta-patterned conditioning stimulation in vivo than do age-matched litter mates (Controls). This increase in LTP appears to reflect an alteration in the induction threshold for synaptic plasticity that accompanies voluntary exercise. Weak theta-patterned stimulation, which did not produce LTP in control subjects, produced a robust and long-lasting LTP in Runners. LTP induction in both groups was dependent upon the activation of N-methyl-D-aspartate (NMDA) receptors, and could be blocked by the competitive antagonist [+/-]-3-[2-carboxypiperazin-4-yl] propanephosphonic acid. Consistent with these findings, we found that mRNA levels for NR2B subtype of NMDA receptor were increased specifically in the DG of Runners. In addition to changes in NR2B mRNA levels, quantitative polymerase chain reaction analysis revealed that brain-derived neurotrophic factor (BDNF) and glutamate receptor 5 mRNA levels were also significantly elevated in the DG of Runners, but not in other areas of the hippocampus. Thus, alterations in the expression of BDNF, and specific glutamate receptor subtypes, may underlie the ability of exercise to enhance neurogenesis and reduce the threshold for LTP in the DG.     

NMR-based investigations of acyl-functionalized piperazines concerning their conformational behavior in solution

Selected N-benzoylated piperazine compounds were synthesized to study their conformational behavior using temperature-dependent ¹H NMR spectroscopy. All investigated piperazines occur as conformers at room temperature resulting from the restricted rotation of the partial amide double bond. In the case of selected mono-N-benzoylated and unsymmetrically N,N′-substituted derivatives, the appearance of the ¹H NMR spectrum was further shaped by the limited interconversion of the piperazine chair conformations. Therefore, two different coalescence points T_C were determined and their resulting activation energy barriers ΔG^‡ were calculated to be between 56 and 80 kJ mol⁻¹. In most of the cases, T_C and ΔG^‡ for the amide site appeared to be higher than the corresponding values for the ring inversion. The influences of substituents on rotational and inversion barriers were analyzed by correlation to Hammett constants. The obtained results are discussed and interpreted in the context of literature data. An additional aryl substituent connected at the amine site led to reduced rotational and inversion barriers compared to the free secondary amine. To support and evidence the findings from the NMR analyses, single crystals of selected piperazines were obtained and XRD analyses were performed. To underline the results, two potential TGase 2 inhibitors were investigated showing energy barriers with similar values.

The influence of substituents on rotational and inversion barriers in benzoylpiperazines was investigated by dynamic NMR and the observed effects were quantified by correlation analyses using Hammett substituent parameters.     

Periprosthetic knee infection. One-stage exchange

Systematic diagnostics and successful therapy of periprosthetic infection of the knee can only be achieved under optimal conditions. History, clinical examination and an elevated CRP level are the basis for suspicion of infection. Diagnosis is confirmed by identification of the pathogen through aspiration of the joint under sterile conditions. The microbiological examination is done in a laboratory, which is specialised in foreign body infections. Identification of the causing pathogens and their resistance pattern are essential to determine the topical and systemic course of antibiotics. When these conditions are fulfilled, the one-stage exchange procedure offers great advantages in comparison with procedures performed in two or more stages for all those involved--patients, surgeons and health care systems--while providing the same chance of a successful elimination of the infection, with an even better functional outcome. Currently, the treatment costs are not adequately reimbursed. In the future, prompt treatment of these especially unfortunate patients will only be possible, if the tremendous resources consumed by these patients are fully covered.     

Das infizierte Implantat

The periprosthetic infection is a permanent risk and a severe complication in joint arthroplasty. Raising numbers of cases, unsatisfactory results of treatment and high cost urge to sufficient prophylactic behaviour in primary surgery and research for new treatment strategies. In the future antibiotic coating of the implants and influence on biofilm could possibly be established. Disciplined early diagnostic measures and rational actions following the established concepts are able to create better results and reduce the extreme high costs.     

Component exchange in treatment of periprosthetic femoral fractures

A retrospective analysis of 893 consecutive periprosthetic femoral fractures treated between 1976 and 2001 shows that component exchange with reimplantation of a cemented long-stem implant can be considered a reliable method of treatment with good functional results and low rates of complications (10%) and revision (7.5%). The possibility of increasing the degree of weight bearing postoperatively at an early stage or even immediate full weight bearing (25%) greatly facilitates mobilization of the mostly elderly and fragile patients. Evaluation according to the Harris Hip Score of the operation and rehabilitation results of a representative sample of 120 patients shows an average value of 85 after a mean period of 6.4 years. The patients' own rating is correspondingly high. In the authors' view, stem exchange is currently the method of choice in the majority of cases because of the rather high rate of stem loosening (77%) at the time of operation, the age-related frequently poor quality or loss of bone substance, and the possibility that the implant material may be damaged. The fact that more than one third of the fractures occurred without significant trauma underlines the importance of this injury as a possible sign of previously unrecognized osteolysis and weakening of the bone as a result of loosening of the prosthesis stem.     

cDNA array approach to cytokine expression profile of aseptic loosened hip arthroplasty

Facts. Aseptic loosening of hip arthroplasties are the main reason for revision operations. Basic research indicates a significant relevance of the interface membrane formed between the implant an the surrounding bone. Their cellular composition and the influence of various factors on the process of aseptic loosening has attracted scientific interest. Cytokines are essential for intracellular communication. Question. Is it possible to reveal differences in the expression profile of cytokines between well-fixed and failed hip arthroplasties using the cDNA array approach? Aim. Generation of a cytokine expression profile characteristic for failed hip arthroplasty. Methods and results. Radioactively labeled cDNA probes were synthesised from mRNA isolated from the interface membrane of six patients with aseptic loosened hip arthroplasty. Using a phosphorimager the analysis of the cDNA arrays revealed nine cytokines which were overexpressed compared with the reference tissue (Calgranulin A, Calgranulin B, IL-10, MCP-1, RANTES, TFDG1, TNFR2, RAI, THYB10). Conclusion. In this study four out of these nine cytokines were found to be connected with the process of aseptic loosening for the first time.     

The infected implant

The periprosthetic infection is a permanent risk and a severe complication in joint arthroplasty. Raising numbers of cases, unsatisfactory results of treatment and high cost urge to sufficient prophylactic behaviour in primary surgery and research for new treatment strategies. In the future antibiotic coating of the implants and influence on biofilm could possibly be established. Disciplined early diagnostic measures and rational actions following the established concepts are able to create better results and reduce the extreme high costs.