[Alloplastic Materials and their Propensity to Bacterial Colonisation]. / Aloplastické materiály z pohledu jejich citlivosti ke kolonizaci bakteriemi.

UNLABELLED: PURPOSE OF THE STUDY The alloplastic materials currently used for protective surface layers on implants were tested in vitro under microbiological laboratory conditions by contamination with microbial agents most frequently found in deep infection of total joint replacements. The objective was to find out how the resistance to bacterial colonisation was related to different surface finishes. MATERIAL AND METHODS Each of 14 samples of alloplastic material currently used in the manufacture of orthopaedic implants was inoculated with each of the group of microorganisms most frequently infecting joint replacements; these were Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, Enterococcus faecalis and Escherichia coli. At 24 hours of incubation, biofilms produced on sample surfaces were collected, stained with crystalline violet and assessed by spectrophotometry. The average value of biofilm absorbances (AV595) for the group of microorganism tested was taken as a basic characteristic of each material sample indicating its sensitivity to bacterial. RESULTS Of the metal materials with smooth surface finish, Vitalium (AV595, 0.368) showed the lowest affinity to microbial colonisation; next was titanium (AV595, 0.459) and steel (AV595, 0.505). A significant increase in sensitivity to bacterial colonisation was recorded in all types of surface finish of steel (AV595, 0.571) and in titanium alloy with a rough surface texture (AV595, 0.737 to 1.676); p < 0.05. Porous titanium surfaces significantly increased material affinity to colonisation. DISCUSSION Our study had certain limitations concerning in vitro evaluation of porous surfaces that have high affinity to bacterial colonisation. Porous titanium, and its hydroxyapatite layer in particular, considerably promotes osteoblast colonisation of the surface as well as implant osseointegration in the bone bed. Microorganisms therefore have no room for surface colonisation. Problematic may remain the surface parts outside contact with bone that keep their affinity to bacterial colonisation. CONCLUSIONS The material of choice for cemented implants is Vitalium which, of all metal surfaces, has the lowest sensitivity to bacterial colonisation. The materials of choice for cementless implants are titanium alloys. However, an osteoactive surface not in contact with bone remains a problem. On the one hand, its roughness and porosity are crucial to good osseointegration, on the other hand, its affinity to bacterial colonisation is high. KEY WORDS: alloplastic material, biofilm, joint replacement infection.

IL-40 is up-regulated in the synovial fluid and cartilage of osteoarthritis patients and contributes to the alteration of chondrocytes phenotype in vitro.

INTRODUCTION: IL-40 is a novel cytokine associated with autoimmune connective tissue disorders such as rheumatoid arthritis (RA) or Sjögren syndrome. We have previously shown an accumulation of IL-40 in the RA joint and its expression by immune cells and fibroblasts. Therefore, we aimed to assess the role of IL-40 in association with hyaline cartilage and chondrocyte activity. METHODS: Immunohistochemistry was employed to detect IL-40 in paired samples of loaded and unloaded regions of osteoarthritis (OA) cartilage (n=5). Synovial fluid IL-40 was analysed by ELISA in OA (n=31) and control individuals after knee injury (n=34). The impact of IL-40 on chondrocytes was tested in vitro. RESULTS: IL-40 was found in chondrocytes of the superficial zone of the OA cartilage, both in loaded and unloaded explants. Additionally, only biopsies from loaded explants showed significant IL-40 positivity in transitional zone chondrocytes. Levels of IL-40 were significantly elevated in the synovial fluid from OA patients compared to controls (p<0.0009) and correlated with synovial fluid leukocyte counts in OA (r=0.444, p=0.014). Chondrocytes exposed to IL-40 dose dependently increased in the secretion of pro-inflammatory cytokines IL-6 (p<0.0001) and IL-8 (p=0.004). Moreover, a dose dependent up-regulation of matrix degrading metalloproteinases MMP-1 (p=0.004), MMP-3 (p=0.031) and MMP-13 (p=0.0002) upon IL-40 treatment was observed in contrast to untreated chondrocytes. CONCLUSION: This study is the first to demonstrate the accumulation of IL-40 in OA cartilage and its up-regulation in the synovial fluid of OA patients compared to controls. In addition, extracellular IL-40 appears to play a role in promoting inflammation and cartilage destruction by driving chondrocyte behaviour towards a more aggressive phenotype.

[Long-term experience with the combined ARBOND hydroxyapatite coating in implant osteointegration]. / Dlouhodobé zkusenosti s kombinovaným hydroxyapatitovým povrchem ARBOND v osteointegraci implantátu.

PURPOSE OF THE STUDY: The hydroxyapatite coating of an implant surface provides osteoactive conditions that can support osteointegration of cementless joint arthroplasties. However, the possibilities of hydroxyapatite degradation, resorption and delamination that may become responsible for failure of total hip arthroplasty (THA) have been reported. The aim of the study was to assess the properties of Arbond hydroxyapatite coating by comparing the long-term survival of implants identical in construction but different in surface coating. MATERIAL: One group (HA) comprised 86 patients (100 THAs) with an average age of 45.14 years (range, 22.3 to 77.4 years) at the time of surgery who received a femoral stem (Walter) with a coating of Arbond sprayed over the proximal half. The other group (control) included 92 patients (100 THAs) with an average age of 49.7 years (range, 33 to 68.7) who had an identical femoral component without coating. In both groups the conical-shaped acetabular cup (Walter) and femoral head made of sintered ceramics were used. The patients in whom one or both components were replaced or extracted were not included in the final clinical evaluation (Harris Hip Score). For the statistical analysis of survival, a stable component still in place at the date of the revision procedure was regarded as surviving; a lose component at the same date was considered a failure. Finally, 71 hips of the HA group followed up for an average of 15.51 (range, 5.6 to 18.56) years and 39 control hips at an average follow-up of 14.19 (range, 6.24 to 18.48) years were clinically evaluated. The data of patients who died in the course of study (HA group, 11; control group, 14) were included in the clinical evaluation with the date of their last follow-up. METHODS: For both groups, the Kaplan-Meier survival curves were constructed for overall survival and for the survival of acetabular and femoral components separately. Differences in survival curves were evaluated with the use of Gehan's Wilcoxon test. Component survival was also calculated using 15-year life-table survivorship analysis. Differences in variables under study were assessed with the use of the two-tailed Student's t-test. A p value of less than 0.05 was considered significant. RESULTS: A total of 29% hips were revised in the HA group, 27% for aseptic loosening of the acetabular cup, in 2% both components were removed because of deep infection. In the control group revision procedures were performed in 61% of the hips. Except for one case of deep infection (1%), the reason was cup loosening in 30%, stem loosening in 12% and both components loosening in 18% of the hips. The HA group showed a significantly longer survival of both total hip prostheses and individual components. The final HHS was significantly better than the initial score in both groups. There was no difference in the degree of improvement between the two groups. The radiographic data showed full osteointegration of stems in the HA group. The control group, on the other hand, had 87% of the stems with translucent lines in zone I and zone VII according to Gruen's classification. DISCUSSION: The significantly longer survival of hips in the HA group gives support to the use of hydroxyapatite coating in total hip arthroplasty. The poorer results in grit-blasted implants, as compared with the literature data, can be explained by allow degree of roughness of the Walter implant surfaces. CONCLUSIONS: The combined Arbond hydroxyapatite coating improves conditions for implant osteointegration in the bone.

Development of autonomic receptors and their function in the chick heart and influence of continuous infusion of carbachol.

The development of heart rate and of muscarinic and beta-adrenergic receptors in chick heart ventricles in the last third of in ovo ontogenesis has been studied. The development of these two types of autonomic receptors does not proceed in parallel. While muscarinic receptors are stable between days 13 and 17, beta-adrenergic receptors significantly decrease in this period. Muscarinic receptors increase their number from the 17th day, and the highest density can be seen after hatching. beta-adrenergic receptors, on the contrary, do not change their density between days 17 and 19, but similarly to muscarinic receptors they increase after hatching (the density after hatching is approximately the same as on the day 13 of embryonic development). We have shown previously that stimulation of one receptor type in the system of autonomic receptors in the heart changes not only the appropriate type of receptor but also the density of the other one. We therefore wondered the information about this in the organism in development. Here we show that when we have infused the eggs in developmental period mentioned above there was no cross-regulation and that muscarinic receptors do not down-regulate. Up-regulation of muscarinic receptors was maintained when the eggs were infused by carbachol from the 13th to 14th day of in ovo development. This muscarinic receptor up-regulation was accompanied with paradoxical increase in heart rate. These events are not proteinkinase (PKC) dependent, as bisindolylmaleimide (PKC inhibitor) do not prevent these changes.