Stage-associated overexpression of the ubiquitin-like protein, ISG15, in bladder cancer.

Bladder cancer is among the most prevalent malignancies, and is characterised by frequent tumour recurrences and localised inflammation, which may promote tissue invasion and metastasis. Microarray analysis was used to compare gene expression in normal bladder urothelium with that in tumours at different stages of progression. The innate immune response gene, interferon-stimulated gene 15 kDa (ISG15, GIP2), was highly expressed at all stages of bladder cancer as compared to normal urothelium. Western blotting revealed a tumour-associated expression of ISG15 protein. ISG15 exhibited a stage-associated expression, with significantly (P<0.05) higher levels of ISG15 protein in muscle-invasive T2-T4 tumours, compared with normal urothelium. Although ISG15 is involved in the primary immune response, ISG15 expression did not correlate with bladder inflammation. However, immunohistochemical staining revealed expression of ISG15 protein in both cancer cells and stromal immune cells. Interestingly, a significant fraction of ISG15 protein was localised to the nuclei of tumour cells, whereas no nuclear ISG15 staining was observed in ISG15-positive stromal cells. Taken together, our findings identify ISG15 as a novel component of bladder cancer-associated gene expression.

Gene expression profiling of noninvasive primary urothelial tumours using microarrays.

At present, the mechanism leading to bladder cancer is still poorly understood, and our knowledge about early events in tumorigenesis is limited. This study describes the changes in gene expression occurring during the neoplastic transition from normal bladder urothelium to primary Ta tumours. Using DNA microarrays, we identified novel differentially expressed genes in Ta tumours compared to normal bladder, and genes that were altered in high-grade tumours. Among the mostly changed genes between normal bladder and Ta tumours, we found genes related to the cytoskeleton (keratin 7 and syndecan 1), and transcription (high mobility group AT-hook 1). Altered genes in high-grade tumours were related to cell cycle (cyclin-dependent kinase 4) and transcription (jun d proto-oncogene). Furthermore, we showed the presence of high keratin 7 transcript expression in bladder cancer, and Western blotting analysis revealed three major molecular isoforms of keratin 7 in the tissues. These could be detected in urine sediments from bladder tumour patients.

Osseointegration of subperiosteal implants using bovine bone substitute and various membranes.

An earlier study revealed incomplete osseointegration of individually made titanium subperiosteal implants covered by ePTFE membranes and fixated to the rabbit tibial bone surface. In addition, the newly-formed bone was dominated by large marrow spaces. In this subsequent study, subperiosteal implants were also fixated on the bone surface of both tibia of 9 Copenhagen White rabbits. Bio-Oss particles were packed densely covering the entire implant surface. One of 3 different membranes covered the implant and the particles. The membranes used were the degradable Polyglactin 910 mesh, a degradable bilayer collagen membrane and the non-degradable ePTFE membrane. Undecalcified sections were prepared for histologic evaluation after a 12 weeks' observation period. All 18 subperiosteal implants were completely osseointegrated. In addition, the marrow spaces were reduced compared to our previous study. The Bio-Oss particles proved to be biocompatible and osteoconductive. The ePTFE membranes revealed neither signs of collapse nor adjacent infiltration of inflammatory cells. The Polyglactin 910 mesh and the bilayer collagen membranes collapsed slightly. There were signs of resorption of the surface of the newly-formed bone under the degradable membranes. The cause of resorption can not be documented.

Incomplete bone regeneration of rabbit calvarial defects using different membranes.

The present study describes the use of a degradable and a non-degradable material for guided bone regeneration. Forty rabbits were divided into 5 groups. Bicortical defects 15 mm in diameter were prepared in rabbit calvaria. A titanium microplate was placed over the defect to prevent collapse of the membrane. The calvarial defects of 2 groups were covered by an outer expanded polytetrafluoroethylene (ePTFE) membrane respectively by a Polyglactin 910 membrane. Bicortical ePTFE membranes or Polyglactin 910 membranes were used in 2 other groups. The defects were not covered by membranes in the control group. Undecalcified sections were prepared for histologic evaluation after an observation period of 8 weeks. Complete bone healing of the defects was not observed in any of the specimens. The Polyglactin 910 material lacks physical strength, resulting in collapse of the membrane and brain tissue herniation into the defects. Subsequently, bone regeneration was impaired. The cellular reactions due to degradation of the material were minor and did not interfere with bone healing. Defects covered bicortically by ePTFE membranes revealed the largest amount of regenerated bone. The ePTFE membrane induced a severe cellular reaction, but no inhibition of bone regeneration was noted.

Unbiased stereological methods used for the quantitative evaluation of guided bone regeneration.

The present study describes the use of unbiased stereological methods for the quantitative evaluation of the amount of regenerated bone. Using the principle of guided bone regeneration the amount of regenerated bone after placement of degradable or non-degradable membranes covering defects in rabbit calvaria was compared. Forty rabbits were divided into 5 groups. A titanium microplate was placed over the defect to prevent collapse of the membrane. The non-degradable expanded polytetrafluoroethylene membrane and the degradable Polyglactin 910 material were both placed unicortically and bicortically. Undecalcified sections were prepared for stereologic evaluation after an observation period of 8 weeks. Complete bone healing of the defects was not observed in any of the specimens. Unbiased stereologic estimates revealed 48% bone regeneration in defects covered by 2 ePTFE membranes, and 12% in defects covered by 2 Polyglactin 910 membranes. Defects covered by 1 ePTFE or 1 Polyglactin 910 membranes revealed 10% or 18% bone regeneration, respectively. The control group regenerated 14%. The major difference of the estimates was caused by real difference between specimens, i.e. biologic variation, whereas only minimal variance was added by the stereologic estimation procedure.

Tissue reaction and material characteristics of four bone substitutes.

The aim of the present study was to qualitatively and quantitatively compare the tissue reactions around four different bone substitutes used in orthopedic and craniofacial surgery. Cylinders of two bovine bone substitutes (Endobon and Bio-Oss) and two coral-derived bone substitutes (Pro Osteon 500 and Interpore 500 HA/CC) were implanted into 5-mm bur holes in rabbit tibiae. There was no difference in the amount of newly formed bone around the four biomaterials. Interpore 500 HA/CC resorbed completely, whereas the other three biomaterials did not undergo any detectable biodegradation. Bio-Oss was osseointegrated to a higher degree than the other biomaterials. Material characteristics obtained by diffuse reflectance infrared Fourier transform spectrometry analysis and energy-dispersive spectrometry did not explain the differences in biologic behavior.

Healing of experimentally created defects: a review.

Within cranio-maxillofacial surgery and orthopedic surgery a bone graft or a bone substitute is required to recontour or assist bony healing in repair of osseous congenital deformities, or in repair of deformity due to trauma or to surgical excision after elimination of osseous disease processes exceeding a certain size. An autogenous bone graft is the optimal material of choice, however its use is problematic due to donor site morbidity, sparse amounts and uncontrolled resorption. Immunological responses and risk of viral contamination of allogenous and xenogenous bone materials make the use of these materials questionable. Healing and degradation of alloplastic materials are inconsistent with subsequent restricted use. The principle of guided tissue regeneration excluding soft tissue cells from a certain area is not alone sufficient to insure complete bony healing. Recombinant bone morphogenetic proteins have with success been added as adjuncts to already known biomaterials. In the future, inductive materials together with a suitable carrier and a biodegradable membrane may be the choice of bone substitute used within cranio-maxillofacial and orthopaedic surgery.

Osseointegration of subperiosteal implant via guided tissue regeneration. A pilot study.

The principle of guided tissue regeneration was applied in an attempt to generate bone to cover a subperiosteal implant. Titanium frame works, casted on individual impressions of the anterior surface of the tibia of 4 Copenhagen White rabbits, were stabilized to the tibia by microscrews, and half of them were covered by an expanded polytetrafluoroethylene augmentation membrane. The observation period was 12 weeks. Guided bone regeneration partly covering the implants was seen at all experimental sides; on the control sides the implants were mainly embedded in fibrous tissue. Studies are in progress with the aim of reducing marked marrow space formation observed in all the regenerated areas.

Unicortical critical size defect of rabbit tibia is larger than 8 mm.

The critical-size defect is important as an experimental model to test bone repair materials. Guided tissue regeneration is an established method for tissue regeneration within periodontal surgery. Bony defects covered by a membrane are allowed to be filled by bony tissue. Healing of 8-mm unicortical trephine defects was tested in Copenhagen White rabbit tibia using 3 different membranes. The critical-size defect in Copenhagen White rabbit tibia is larger than 8 mm, because control defects 8 mm in diameter healed spontaneously. However, it is anatomically not possible to create defects larger than 8 mm in an adult Copenhagen White rabbit tibia.