The monomer, p-acryloyloxybenzoic acid (ABA) was synthesized by condensation reaction of acryloyl chloride and p-hydroxybenzoic acid in alkaline medium. Polymerization of the monomer and grafting of the produced polymer (PABA) onto high density polyethylene (HDPE) were expected to be carried simultaneously in melt mixing at high temperature. The graft copolymerization was studied at varying concentrations of the monomer in the reaction mixture at constant temperature (200 0C). Grafted HDPE samples were investigated by several techniques such as DSC, FTIR, MFI and mechanical testing. The tensile tests of PABA-g-HDPE showed an improvement particularly in stress at yield and Young&rsquo / s modulus whereas the strain at break values showed a decrease for all compositions compared to neat HDPE.

Durchtrennte Axone adulter retinaler Ganglienzellen (RGZ) können in periphere Nerventransplantate (PNT) einwachsen, die als “bypass” des distalen Sehnervenstumpfes verwendet werden. Das Transplantationsmodell, bei dem der durchtrennte Sehnerv durch ein Ischiasnervsegment ersetzt wird, ist in der Regenerationsforschung ein seit Jahren fest etabliertes Verfahren. In dieser Arbeit soll der Frage nachgegangen werden, ob a) der Ersatz des Sehnervs durch ein peripheres Nervensegment RGZ über einen langen Zeitraum hinweg morphologisch und funktionell stabilisiert, ob b) Unterschiede der Stabilisierung in Abhängigkeit von der Hirnregion, mit der das PNT in Kontakt tritt, zu beobachten sind und c) inwieweit regenerierende RGZ dadurch selbst peripher-nervöse Eigenschaften annehmen. Der Sehnerv adulter Ratten wurde zunächst komplett intraorbital durchtrennt. Der okuläre Stumpf wurde über ein autologes Ischiasnervsegment mit verschiedenen visuellen Zentren (Kortex, Mittelhirn) oder mit Fremdzielgebieten (z. B. Muskel) verbunden. Weitere Kontrollgruppen bestanden in der Quetschung des Sehnervs, der Durchtrennung ohne Transplantation und der Transplantation mit blind endendem Transplantat. Die Netzhautintegrität wurde pupillometrisch und elektroretinographisch regelmäßig überprüft, um eine eventuelle, funktionelle Wiederherstellung der visuellen Bahn zu erfassen. Nach einem, sechs und neun Monaten wurden die regenerierenden bzw. axotomierten oder gequetschten RGZ mit 4-(4-(didecylamino)styryl)-N-methylpyridinium (4-Di-10-ASP) retrograd markiert und morphometrisch quantifiziert (Fluoreszenz-, Konfokal- und Elektronenmikroskopie sowie Differentialinterferenzkontrast). Zusätzlich wurden immunhistochemische und anterograde Markierungsuntersuchungen durchgeführt. Regenerierende Ganglienzellen bleiben bis neun Monate nach der Transplantation am Nervus opticus stabil. Es gibt quantitative sowie morphometrisch erfassbare Unterschiede zwischen den experimentellen Gruppen und den Kontrollen, wobei die wieder verbundenen Ganglienzellen morphologisch am besten zu klassifizieren sind. Quantitativ zeigen die Retinae mit gequetschtem Sehnerv nach sechs Monaten die höchste Überlebensrate der RGZ. Die Effektivität dieses Verfahrens als Modell der zentralen Nervenläsion darf in Folge dieser Ergebnisse in Frage gestellt werden. Nach neun Monaten sind in den Retinae mit Rekonnektion zum Mittelhirn die meisten Ganglienzellen vorhanden. Elektrophysiologisch zeigen die Augen mit Verbindung zum Muskelgewebe die besten funktionellen Ergebnisse. Schlussfolgernd zeigt sich, dass adulte RGZ der Ratte über ein peripher-nervöses Transplantat, welches mit visuellen Zentren in Verbindung steht, über lange Zeit stabilisiert werden können.

Spinal cord injury results in complete failure of the central neurons to regenerate and is associated with cyst formation and enlargement of the trauma zone. In contrast to the spinal cord, axons in the injured peripheral nerve have the capacity to undergo some spontaneous regeneration. However, significant post-traumatic loss of nervous tissue causing long nerve gap is one of the main reasons for the poor restoration of function following microsurgical repair of injured nerves. The present thesis investigates the effects of biodegradable conduits prepared from fibrin glue and poly-beta-hydroxybutyrate (PHB) in combination with cultured Schwann cells, mesenchymal stem cells and extracellular matrix molecules on regeneration after spinal cord and peripheral nerve injury in adult rats. At 4-8 weeks after transplantation into the injured spinal cord, the PHB conduit was well integrated into the cavity but regenerating axons were found mainly outside the PHB. When suspension of BrdU-labeled Schwann cells was added to the PHB, regenerating axons filled the conduit and became associated with the implanted cells. Modification of the PHB surface with extracellular matrix molecules significantly increased Schwann cell attachment and proliferation but did not alter axonal regeneration. To improve the labeling technique of the transplanted cells, the efficacy of fluorescent cell tracers Fast Blue, PKH26, Vibrant DiO and Cell Tracker™ Green CMFDA was evaluated. All tested dyes produced very efficient initial labeling of olfactory ensheathing glial cells in culture. The number of Fast Blue-labeled cells remained largely unchanged during the first 4 weeks whereas the number of cells labeled with other tracers was significantly reduced after 2 weeks. After transplantation into the spinal cord, Fast Blue-labeled glial cells survived for 8 weeks but demonstrated very limited migration from the injection sites. Additional immunostaining with glial and neuronal markers demonstrated transfer of the dye from the transplanted cells to the host tissue. In a sciatic nerve injury model, the extent of axonal regeneration through a 10mm gap bridged with tubular PHB conduit was compared with a fibrin glue conduit. At 2 weeks after injury, the fibrin conduit supported similar axonal regeneration and migration of the host Schwann cells compared with the PHB conduit augmented with a diluted fibrin matrix and GFP-labeled Schwann cells or mesenchymal stem cells. The long-term regenerative response was evaluated using retrograde neuronal labeling. The fibrin glue conduit promoted regeneration of 60% of sensory neurons and 52% of motoneurons when compared with the autologous nerve graft. The total number of myelinated axons in the distal nerve stump in the fibrin conduit group reached 86% of the nerve graft control and the weight of gastrocnemius and soleus muscles recovered to 82% and 89%, respectively. When a fibrin conduit was used to bridge a 20mm sciatic nerve gap, the weight of gastrocnemius muscle reached only 43% of the nerve graft control. The morphology of the muscle showed more chaotic appearance and the mean area and diameter of fast type fibers were significantly worse than those of the corresponding 10mm gap group. In contrast, both gap sizes treated with nerve graft showed similar fiber size. In summary, these results show that a PHB conduit promotes attachment, proliferation and survival of adult Schwann cells and supports marked axonal growth after transplantation into the injured spinal cord. The data suggest an advantage of the fibrin conduit for the important initial phase of peripheral nerve regeneration and demonstrate potential of the conduit to promote long-term neuronal regeneration and muscle recovery.

Pathological processes in the alveolar and facial bones can lead to bone loss that may not heal with complete regeneration. Biomaterials can be used to facilitate the healing process and/or as a bone substitute, but the mechanisms are not fully understood. Persistent leakage of bacteria/bacterial toxins, after root canal treatment, may lead to a residual bone defect. The healing is dependent on a placed dental biomaterial providing a tight seal. The composition of the filling material may also influence the healing process. The general aim of this study is to investigate surface properties and biological interactions of biomaterials used in dento-alveolar surgery. A dental biomaterial, a bonded compomer (DAP) containing a corroding glass filler, was used as a root end filling material, promoting a new operation technique. The healing (assessed according to Molven´s x-ray criteria) demonstrates a significant improvement in healing results for the compomer group, compared to a commonly used technique. The surface properties and biological interactions of DAP were analyzed. ICP-OES of DAP cell culture medium extract demonstrated a significant release of Sr, Si and F from the dental biomaterial. Human periodontal ligament (PDL) cells grew on and around DAP specimens without any sign of toxic reactions. DAP extract stimulated proliferation of PDL cells, but caused an inhibition of osteoblastic gene expression in mouse bone marrow cells. The surface properties of the glass containing compomer may contribute to improved healing of the periapical lesions. A bovine inorganic bone graft substitute (BO) is commonly used as a treatment option in dento-alveolar surgery with new bone formation in immediate close contact with BO material. ICP-OES dissolution analysis of cell culture media, after incubation with BO particles, demonstrated a dosedependent release of Si and a decrease of Ca and P. An uptake of Ca from the medium to the BO particle was demonstrated with calcium-45 labeling. The Si dissolution varied between different batches, possibly reflecting a variation in food intake in the animals. Stimulated osteogenic response was seen in close contact to the BO particles in cell cultures. Furthermore, it was clearly demonstrated that the study design is a critical factor for correctly understanding biomaterials’ biological interactions. The surface properties of three bone graft substitutes reported to have good results in dento-alveolar surgery were investigated, in order to establish whether or not dissolution-precipitation reactions could contribute to the bone healing. Dissolution-precipitation extracts of BO, bioactive glass 45S5 (BG) and a marine algae hydroxyl apatite (AP) in cell culture media were analyzed. Dissolution of Si at significant levels was detected for BO and 45S5 over time. Significant uptake levels of Ca and P from the culture were seen for both 45S5, BO and AP but at different times. Surface analysis of the biomaterials with SEM/EDAX, before and after immersion in cell culture media, revealed a smoothing of the surface morphology for 45S5 over time. No obvious alterations for BO and AP were detected. Ca/P ratio decreased significantly for 45S5, but no major changes were detected by XPS for BO or AP. XPS further demonstrated a surface charge for BO, changing from negatively to positively charged when exposed to serum. 45S5 and AP had positive surface charges, both in the absence and the presence of serum. These demonstrated surface changes in biomaterials could contribute to adherence of cells and subsequently affect bone healing. Conclusion: Biomaterials used in dento-alveolar surgery interact with biological surroundings through surface and dissolution-precipitation reactions which may have implications for bone healing.

The most common cause for revision total hip replacement surgey is aseptic loosening of the acetabular component. This thesis explores the effect of three techniques to improve the depth and quality of cemented acetabular component fixation in primary total hip replacement. This may have beneficial effects on the longevity of cemented acetabular components and reduce the rate of revision surgery for aseptic loosening. Aims: 1. Determine the effect of the rim cutter on cement pressure during cup insertion. 2. Examine the effect of the rim cutter on cement penetration distance. 3. Evaluate the effect of bone grafting of the acetabular notch. 4. Determine the effect of iliac suction during cement pressurisation. 5. Compare the behaviour of bone cement with Play Dough. Materials and Methods: 1. Sawbones hemi pelvis models were fitted with pressure transducers at the rim and apex of the acetabulum. Peak pressure was measured upon insertion of cups with different flange sizes and when the acetabulum was prepared with the rim cutter. 2. Foam cavities were used to measure the depth of cement penetration when the same cups and rim cutter were used. 3. Hemi pelvis models were modified to simulate bone grafting of the acetabular notch. Again, pressure sensors were mounted at the apex and rim of the acetabulum. Intra-acetabular cement pressure was compared with native acetabulae. 4. A back bleeding model of the acetabulum was fitted with a suction catheter. The effect on cement penetration into cancellous bone was measured compared with no suction. 5. Play Dough pressurisation and penetration into hemi pelvises and foam was compared to bone cement. Results: 1. Significant increase in peak apex and rim pressures when flanged cup inserted into an acetabulum prepared with the rim cutter compared with both flanged and unflanged cups alone. 2. Significant increase in cement penetration at the rim of the acetabulum when rim cutter used and flanged cup inserted when compared with flanged and unflanged cups alone. 3. Significant increase in intra-acetabular pressure when cement pressurised in presence of simulated acetabular notch bone grafting compared with normal acetabulae. 4. Significant increase in cement penetration distance when suction used compared with no suction. 5. Significant differences in the flow characteristics between bone cement and Play Dough. Conclusion: The authors recommend preparation of the acetabular rim with the rim cutter and bone grafting of the acetabular notch to improve the depth and uniformity of the cement mantle in cemented primary THA. Play Dough at room temperature is not a suitable substitute for bone cement in in-vitro cementing studies.

Thesis (Ph.D. in Immunology) -- University of Colorado at Denver and Health Sciences Center, 2006. / Typescript. Includes bibliographical references (leaves 151-168). Free to UCDHSC affiliates. Online version available via ProQuest Digital Dissertations;

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2006. / Härtill 5 uppsatser.

Diss. (sammanfattning) Umeå : Univ., 2007. / Härtill 4 uppsatser.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The present research had the objective to evaluate the use of an n-butil cyanoacrylate in the fixation and maintenance of corneal autografts and aloimplants in the penetrating keratoplasty. There were used eight adult rabbits divided in two groups: the group I adhesive (GI 4 animals) and group II suture (GII 4 animals). In the GI, performed in the left eye, a penetrating keratoplasty with 5 mm in diameter received a 6 mm in diameter alogenous corneal button preserved in glycerin 98%, fixed with 4 simple interrupted stitches and with cyanoacrylate adhesive. In the right eye, the same procedure were done, but with a 4 mm in diameter defect with corneal left button that was removed (5 mm). In the GII, a similar procedure were done, but the corneal buttons were fixed with 8 simple interrupted stitches with mononylon 10-0. The pos-operatory (PO) ophthalmic evaluation were used the computer videoceratoscopy, ultrasound pachimetry and scanning eletronic microscopy. It was verified the integration of both transplants in both grafts. A bigger astigmatism grade were observed in the autotransplants from GI, and also with a lesser endothelial density. The pachimetry, were verified the decrease of the corneal thickness as the time elapsed. In all animals it was noted a complete endothelial progressive over the grafst and implants. It was concluded that the cyanoacrylate adhesive can be used as a fixative method in corneal autotransplants and also in corneal alografts in rabbits. / A procura de alternativas para a fixação dos enxertos utilizados em defeitos corneais é realizada de forma incessante. Os cianoacrilatos são monômeros líquidos que em contato com a umidade polimerizam-se e solidificam-se rapidamente ocasionando a adesão nos tecidos. São utilizados em diversas situações clínicas na oftalmologia humana e veterinária. O presente trabalho teve como objetivo, avaliar o uso de um adesivo a base de n-butil cianoacrilato na fixação e manutenção de botões corneais autógenos e alógenos na ceratoplastia penetrante. Para tanto foram usados 16 coelhos divididos em dois grupos: O grupo I adesivo (GI 8 animais) e grupo II sutura (GII 8 animais). No GI, foi realizada, no olho esquerdo, uma ceratoplastia penetrante de 5 mm utilizando-se córnea alógena conservada em glicerina de 6 mm de diâmetro e fixando-a com 4 pontos isolados simples e adesivo de cianoacrilato sobre as bordas. No olho direito também foi realizada uma ceratoplastia penetrante, porém de 4 mm de diâmetro utilizando-se o botão que foi removido da córnea esquerda (5 mm) com o mesmo método de fixação. No GII procedimentos semelhantes fora realizados, porém, a fixação dos botões constou de 8 pontos isolados simples. Avaliações oftálmicas pós-operatórias (PO) foram realizadas. Aos 0 (antes dos procedimentos) 60 e 90 dias PO foram realizadas a videoceratoscopia computadorizada e a paquimetria ultra-sônica. Ao final do período de avaliação, as córneas foram avaliadas à microscopia eletrônica por varredura. Foi verificada a integração de ambos os transplantes em ambos os grupos. Houve um maior grau de astigmatismo visto nos transplantes autógenos do GI e, neste grupo a densidade endotelial foi menor. À paquimetria, foi verificada a diminuição da espessura conforme aumentavam os tempos. Em todos os animais houve a completa progressão do endotélio corneal sobre o aloimplante. Conclui-se que o adesivo de cianoacrilato pode ser usado como método de fixação de autotransplantes bem como alotransplantes de córnea em coelhos.

Na ortopedia veterinária, o enxerto ósseo é comumente utilizado em uma variedade de procedimentos ou afecções ortopédicas como artrodeses, fusões espinhais, reparo de fraturas, tratamentos de união atrasada e não-união de fraturas, preenchimento de falhas ósseas, osteotomias corretivas e reconstruções após a ressecção de neoplasia óssea. O uso de enxerto ósseo alógeno, comparado com o enxerto autógeno, tem como vantagens menor morbidez e dor pós-cirúrgica, diminuição do tempo cirúrgico e, principalmente, fornecimento de maior volume ósseo para a reconstrução adequada de uma grande falha óssea. As desvantagens do seu uso são os riscos de reação imunológica e transmissão de doenças, além da necessidade da formação de um banco de ossos, o que aumenta os custos e necessita de espaço apropriado. O objetivo do presente trabalho foi avaliar a taxa e a forma de incorporação do aloenxerto ósseo cortical submetido ao congelamento em nitrogênio líquido e inserido em tíbias de ovelhas, visando à preservação do membro locomotor. Seis ovelhas clinicamente sadias, da raça Corriedale, com idade estimada entre dois e três anos, foram submetidas à avaliação radiográfica pré-operatória das tíbias para que fosse descartada qualquer alteração óssea. Simultaneamente, realizou-se a ostectomia da diáfise tibial de duas ovelhas para a retirada de um segmento de 7 cm que, após a remoção do periósteo e da medula óssea, foi imerso em nitrogênio líquido, tendo como finalidade a desvitalização óssea, e implantado imediatamente no outro paciente. A estabilização entre os fragmentos e o implante ósseo foi realizada com placa cirúrgica de compressão dinâmica (PCD). Após os procedimentos cirúrgicos, foram realizadas avaliações clínicas e radiográficas a cada 30 dias até o 180º dia de pós-operatório. Aos 60 dias de pós-operatório já se observava o completo uso funcional do membro operado. A união radiográfica das interfaces proximal e distal e a consolidação óssea ocorreram em tempo médio de 95 dias em todos os animais. Conclui-se que o aloenxerto ósseo cortical submetido ao congelamento em nitrogênio líquido é um método apropriado para a preservação do membro locomotor, tendo em vista que a incorporação do mesmo ocorreu gradualmente e a taxa foi de 100%. / Bone grafting is employed in veterinary orthopedics with a variety of purposes as for arthrodesis, spinal fusions, fracture repairs, treatment of delayed or non-unions, filling bone defects, supporting corrective osteotomy, and as replacement in limb sparing techniques for tumor resection. The allograft bone, in contrast to the autologous bone graft, is associated with less site-donor morbidity and pain, reduced surgical time, and adequate bone supply to fill greater defects. Still, the allogeneic bone, besides requiring the establishment of a bone bank, can be a source of diseases and may induce immunogenic response. This study evaluated the allogeneic cortical bone graft incorporation after submission of the harvested fragment to a bout freezing in liquid nitrogen. Six adult clinically healthy sheep were submitted to a 7cm ostectomy of the tibial diaphysis. After removal of periosteum and bone marrow, the fragment was submersed in liquid nitrogen and implanted in another sheep missing a same-sized segment at the corresponding bone. Stabilization of the allograft in the host bone was accomplished by a dynamic compressive plate (DCP). Clinical and radiographic evaluations were performed in the immediate post-operatory period and in every 30 days for six months after surgery. The proximal and distal host-graft interfaces showed radiographic union at a mean postoperative time of 95 days in all the animals. The cortical bone allograft submitted to liquid nitrogen freezing provided adequate bone healing in the sheep model, representing a feasible alternative for limb preservation techniques.