The immunomodulatory effects of probiotics and azithromycin in dextran sodium sulfate-induced ulcerative colitis in rats via TLR4-NF-κB and p38-MAPK pathway

Ulcerative colitis (UC), a chronic autoimmune disease of the gut with a relapsing and remitting nature, considers a major health-care problem. DSS is a well-studied pharmacologically-induced model for UC. Toll-Like Receptor 4 (TLR4) and its close association with p-38-Mitogen-Activated Protein Kinase (p-38 MAPK) and nuclear factor kappa B (NF-κB) has important regulatory roles in inflammation and developing UC. Probiotics are gaining popularity for their potential in UC therapy. The immunomodulatory and anti-inflammatory role of azithromycin in UC remains a knowledge need. In the present rats-established UC, the therapeutic roles of oral probiotics (60 billion probiotic bacteria per kg per day) and azithromycin (40 mg per kg per day) regimens were evaluated by measuring changes in disease activity index, macroscopic damage index, oxidative stress markers, TLR4, p-38 MAPK, NF-κB signaling pathway in addition to their molecular downstream; tumor necrosis factor alpha (TNFα), interleukin (IL)1β, IL6, IL10 and inducible nitric oxide synthase (iNOS). After individual and combination therapy with probiotics and azithromycin regimens, the histological architecture of the UC improved with restoration of intestinal tissue normal architecture. These findings were consistent with the histopathological score of colon tissues. Each separate regimen lowered the remarkable TLR4, p-38 MAPK, iNOS, NF-κB as well as TNFα, IL1β, IL6 and MDA expressions and elevated the low IL10, glutathione and superoxide dismutase expressions in UC tissues. The combination regimen possesses the most synergistic beneficial effects in UC that, following thorough research, should be incorporated into the therapeutic approach in UC to boost the patients' quality of life.

A nanofibrous cell-seeded hydrogel promotes integration in a cartilage gap model

The presence of a defect in mature articular cartilage can lead to degenerative changes of the joint. This is in part caused by the inability of cartilage to regenerate tissue that is capable of spanning a fissure or crack. In this study, we hypothesized that introduction of a biodegradable cell-seeded nanofibrous hydrogel, Puramatrix(), into a cartilage gap would facilitate the generation of a mechanically stable interface. The effects of chondrocyte incorporation within the hydrogel and supplementation with transforming growth factor-beta3 (TGFbeta3), a known regulator of cell growth and differentiation, on cartilage integration were examined mechanically and histologically as a function of cell density and incubation time. When supplemented with TGFbeta3, the cell-seeded hydrogel exhibited abundant matrix generation within the hydrogel and a corresponding increase in maximum push-out stress as compared to all other groups. Furthermore, initial cell seeding density affected interfacial strength in a time-dependent manner. This study suggests that a cell-seeded TGFbeta3-supplemented hydrogel can encourage integration between two opposing pieces of articular cartilage.

Nondegradable hydrogels for the treatment of focal cartilage defects

Nondegradable materials have long been suggested for the treatment of articular cartilage defects; however, the mechanics of the implant/tissue system necessary to ensure long-term function are unknown. The objective of this study was to explore the performance of nondegradable hydrogel implants in cartilage defects. Our hypothesis was that the structural integrity of the implant and surrounding tissue would be influenced by the compressive modulus of the material used, and that superior results would be obtained with the implantation of a more compliant material. Poly(vinyl alcohol)-poly(vinyl pyrrolidone) hydrogel implants of two different moduli were implanted into osteochondral defects in a rabbit model. Six-month postoperative histological and mechanical data were used to assess the wear and fixation of the implants. The compliant implants remained well fixed and a thin layer of soft tissue grew over the surface of the implants. However, gross deformation of the compliant implants occurred and debris was evident in surrounding bone. The stiffer implants were dislocated from their implantation site, but with no accompanying evidence of debris or implant deformation. Our hypothesis that superior results would be obtained with implantation of a more compliant material was rejected; a compromise between the wear and fixation properties dependent on modulus was found.

Influence of acetabular rim profile on hip dislocation

Dislocation is the second most common complication in total hip arthroplasty, with reported incidences of up to 8 per cent. The authors' hypothesis is that, by modifying the rim of an acetabular component in order to shift the femoral neck contact position towards the periphery of the acetabulum, the torque required to dislocate the hip joint can be increased without reducing the range of motion. Three liners were designed and their dislocation characteristics mechanically evaluated using a custom experimental test jig designed to simulate the seated leg-cross. On the basis of torque and energy to dislocate and angle at dislocation, the hypothesis was accepted; geometrically varying the contact area between the femoral neck and the acetabular rim appear to be a powerful way to modify hip dislocation characteristics.

Discriminating the loosening behaviour of cemented hip prostheses using measurements of migration and inducible displacement

In vitro pre-clinical tests of hip prostheses have not yet been developed to the extent that inferior prostheses can be 'screened-out' prior to animal or clinical trials. This paper reports the experimental part of a project to develop a pre-clinical testing platform for cemented femoral hip implants. It is based on the clinical observation (Kärrholm et al. JBJS, 76B (1994) 912-916) that higher subsidence (distal migration) correlates with early revision of hip prostheses. A protocol to measure the relative movement between implant and bone was designed to test whether or not such a measurement, if made in a laboratory, could discriminate between hip prostheses. The protocol was applied to the Lubinus SPII prosthesis (W. Link, Germany) and a Müller Curved Stem (JRI Ltd., UK)-these prostheses were chosen because they are known to have different loosening rates in vivo. Five prostheses of each design were tested. The migration, the rate-of-migration, and the inducible displacement of each prosthesis was recorded over two million cycles of loading. For each implant, rapid initial migration was found, followed by a period of steady-state migration. In the majority of cases, the prostheses migrated medially, distally and posteriorly. On average, the Lubinus migrated less than the Müller in all directions. The average Lubinus migration was less than half that of the Müller, and this difference was significant at a level of p=0.05. Inducible displacement was greater for the Müller compared to the Lubinus. Furthermore, the inducible displacement decreased over time for the majority of Lubinus prostheses whereas it increased over time for the majority of the Müller prostheses leading to the conclusion that a rapid pre-clinical test based on measurement of inducible displacement may be possible.

Measurement of the migration of a cemented hip prosthesis in an in vitro test

OBJECTIVE

To develop a method to measure the migration of a cemented hip prosthesis in an in vitro experimental test.

DESIGN

A device to measure prosthesis movement relative to bone was designed and fabricated. It was tested using a Lubinus prosthesis (W. Link, Germany) implanted in a composite femur.

BACKGROUND

Clinical studies using radiostereophotogrammetry have shown that those cemented hip prosthesis that migrate rapidly in the first two post-operative years are the ones that require early revision. If migration be used as a basis for a pre-clinical test, then it should be possible to screen-out inferior designs before implantation in animal or clinical trials.

METHODS

The micromotion measurement device consisted of a 'target' of three spheres arranged in a cruciform structure. Six linear variable displacement transducers were aligned with the spheres so that motion of the prosthesis relative to the bone could be measured.

RESULTS

The displacement and rotation of the prosthesis relative to the composite femur was recorded for two million cycles. Relative rapid initial migration was found, followed by a period of steady-state migration. Distal migration (called 'subsidence' in this paper) of up to 0.1 mm was measured; however the variability in absolute prosthesis migration was very high despite efforts to ensure that all extraneous factors were minimised. In the majority of cases, the prostheses migrated medially, distally and anteriorly. The absolute subsidence, and its variability, were similar to that recorded clinically.

CONCLUSIONS

A method has been designed and tested which measures prosthesis migration in an experimental test. It provides a basis for a pre-clinical testing standard. Relevance. Hip prostheses need to be tested experimentally before implantation. However, no reliable test exists for such experimental tests. Rapid migration of a cemented prosthesis relative to bone has been shown in vivo to correlate with early failure, and in this paper a method to make such migration measurements in vitro is described and tested.

Design and validation of a machine for reproducible precision insertion of femoral hip prostheses for preclinical testing

Preclinical testing of orthopaedic implants is becoming increasingly important to eliminate inferior designs before animal experiments or clinical trials are begun. Preclinical tests can include both laboratory bench tests and computational modeling. One problem with bench tests is that variability in prosthesis insertion can significantly influence the failure rate; this makes comparison of prostheses more difficult. To solve this problem an insertion method is required that is both accurate and reproducible. In this work, a general approach to the insertion of hip prostheses into femoral bones is proposed based on physically replicating an insertion path determined using computer animation. As a first step, the seated prosthesis position is determined from templates and femur radiographs. Three-dimensional images of the prosthesis and bone are then imported into computer animation software and an insertion path in the coronal plane is determined. The insertion path is used to determine the profile of a cam. By attaching the prosthesis to a carriage, which is pneumatically moved along this cam, the required insertion motion of the prosthesis in the coronal plane can be achieved. This paper describes the design and validation of the insertion machine. For the validation study, a nonsymmetric hip prosthesis design (Lubinus SPII, Waldemar Link, Germany) is used. It is shown that the insertion machine has sufficient accuracy and reproducibility for preclinical mechanical testing.

Quantification of interdigitation at bone cement/cancellous bone interfaces in cemented femoral reconstructions

The mechanical interlock created at the cement/cancellous bone interface in cemented femoral reconstructions is crucial to the longevity of the replacement. To accurately model the mechanics of the interface, its morphological features must be quantified. This paper applies a semi-automated procedure to the analysis of the cement/bone interdigitation characteristics of six cemented femora: two which have been prepared in vivo and later retrieved, and four which were prepared in vitro. A parameter which combines the undulations of the cement/bone interface in a transverse slice into one value, is used to explore the trends in the interlock along the length of the femur. The differences in the interdigitation produced in the in vivo and in vitro groups are also explored.