<p>Includes Bibliographical references (leaves 83- 94).Forty-three male athymic nude mice were implanted with human vaginal mucosal cysts under general anaesthesia with Ketamine [25mg/kg] and Medetomidine [0.5mg/kg]. Cysts in 37 mice were recovered after 9 weeks of growth. twenty three cyst linings had retained the original structure of the vaginal epithelium. No marked deifference was present between the thickness of 9 week old linings and donor vaginal epithelium. The contaminants isolated from the skin of mice before implantation were mainly normal commercals of healthy experimental animals. There was no distinct difference in the number of cases with intact cyst formation between the terramycin/vitamin cocktaik group. The frequency of poor wound healing and/ or murine epidermis ingrowth was three times higher in animals stitched with silk sutures that in those cases where nylon sutures were used.</p>

<p>Includes Bibliographical references (leaves 83- 94).Forty-three male athymic nude mice were implanted with human vaginal mucosal cysts under general anaesthesia with Ketamine [25mg/kg] and Medetomidine [0.5mg/kg]. Cysts in 37 mice were recovered after 9 weeks of growth. twenty three cyst linings had retained the original structure of the vaginal epithelium. No marked deifference was present between the thickness of 9 week old linings and donor vaginal epithelium. The contaminants isolated from the skin of mice before implantation were mainly normal commercals of healthy experimental animals. There was no distinct difference in the number of cases with intact cyst formation between the terramycin/vitamin cocktaik group. The frequency of poor wound healing and/ or murine epidermis ingrowth was three times higher in animals stitched with silk sutures that in those cases where nylon sutures were used.</p>

Magister Scientiae Dentium - MSc(Dent) / Includes Bibliographical references (leaves 83- 94).Forty-three male athymic nude mice were implanted with human vaginal mucosal cysts under general anaesthesia with Ketamine [25mg/kg] and Medetomidine [0.5mg/kg]. Cysts in 37 mice were recovered after 9 weeks of growth. twenty three cyst linings had retained the original structure of the vaginal epithelium. No marked deifference was present between the thickness of 9 week old linings and donor vaginal epithelium. The contaminants isolated from the skin of mice before implantation were mainly normal commercals of healthy experimental animals. There was no distinct difference in the number of cases with intact cyst formation between the terramycin/vitamin cocktaik group. The frequency of poor wound healing and/ or murine epidermis ingrowth was three times higher in animals stitched with silk sutures that in those cases where nylon sutures were used. / South Africa

Thesis (Ph.D)--Biomedical Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Bellamkonda, Ravi; Committee Member: Babensee, Julia; Committee Member: Butera, Robert; Committee Member: DeWeerth, Steve; Committee Member: Lee, Robert; Committee Member: McKeon, Robert. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (118-130)--University of Washington, 2007. / Vita. Includes bibliographical references (leaves 118-130).

No description available.

Cochlear implants (CIs) help to restore basic auditory function in patients who are deaf or have profound hearing loss. However, CI patients suffer from limited voice and tonal perception due to spatial separation between the stimulating CI electrode and the receptor spiral ganglion neurons (SGNs). Directed regeneration of proximate SGN axons may improve tonal performance and implant fidelity by decreasing the spatial separation between the CI electrode and the neural receptor. Additionally, fibrous scar tissue formation on the surface of implanted electrodes further decreases tonal perception through current attenuation and spreading resulting in late-term hearing loss. Thus, designing surfaces that induce favorable responses from neural tissues will be necessary in overcoming signal resolution barriers. In this work, the inherent spatial and temporal control of photopolymerization was used to functionalize surfaces with topographical and biochemical micropatterns that control the outgrowth of neural and other cell types. First, laminin, a cell adhesion protein was patterned using a photodeactivation process onto methacrylate polymer surfaces and was shown to direct the growth of spiral ganglion neurons (SGN), the primary auditory neural receptors. These protein patterns could even overcome low amplitude/high periodicity competing topographical cues. Additionally, glass substrates were patterned with linear zwitterionic polymers and fibroblasts, astrocytes, and Schwann cells all showed dramatically decreased cell adhesion on 100 µm precocity patterns. Further, SGN neurites showed excellent alignment to these same patterns. Next, poly(dimethyl siloxane) (PDMS) was coated with a crosslinked zwitterionic thin film using a single step photografting/photopolymerization process to covalently bind the hydrogel to PDMS. These coated surfaces showed dramatically lower levels of protein, cell, and bacterial adhesion. Finally, zwitterionic hydrogels were strengthened by changing the concentration of poly(ethylene glycol) diacrylate (PEGDA) and 2-hydroxyethyl methacrylate (HEMA) in the formulation. The direct relationship between changing zwitterionic hydrogel formulation to strengthen the hydrogel and the anti-fouling properties were established. The fundamental understanding and design of cochlear implant materials described herein serves as a foundation for the development of next generation neural prosthetics.

<p>The success of implanted medical devices, such as biosensors, is dependent on the immune reaction to the surface of the implanted material. This immune reaction, termed the foreign body reaction, is potentially affected by the physical and chemical properties of the implanted material. Macrophages interact with the surface of the implanted material and secrete intercellular signals, including cytokines and growth factors, which direct the actions of immune cells in the surrounding tissue. The type and quantity of cytokines and growth factors produced by macrophages at an implant surface could be an indicator of the outcome of the foreign body reaction. </p><p>This study investigated the effect of the surface chemistry of an implanted device on the production of cytokines and growth factors. First, microdialysis sampling was characterized as a technique for collecting cytokines and growth factors from the tissue surrounding an implant. Based on this characterization, it was determined that a direct sampling method would be more suitable than microdialysis sampling for determining accurate tissue concentrations of cytokines and growth factors. Second, an in vitro model was developed and utilized to assess cytokine and growth factor production from monocyte/macrophage cultures seeded onto commonly implanted polymeric biomaterials with varying surface chemistries. The materials included in this study were polyethylene (PE), polyurethane (PU), polymethyl methacrylate (PMMA), expanded polytetrafluoroethylene (ePTFE), and a cytotoxic organo-tin polyvinyl chloride (ot-PVC) as a positive control. From this in vitro model, it was determined that the varying surface chemistries of these non-toxic materials, excluding ot-PVC, did not significantly affect the types and quantities of cytokines and growth factors produced. Finally, an in vivo model for evaluating the cytokine and growth factor response to an implanted biomaterial was utilized for comparison with the in vitro findings. In this model, biomaterials were implanted subcutaneously within the lumen of a stainless steel mesh cage. The mesh cage served to create a "pocket" where wound exudate fluid collected within the cage, surrounding the implanted biomaterial. The materials included in this study were PE, PU, and ot-PVC. Cytokines and growth factors produced at the material surface were sampled directly from the exudate fluid. The results from this in vivo study indicate that cytokine and growth factor production were not significantly impacted by the varying surface chemistries of the implanted biomaterials. The in vivo data support the findings from the in vitro model, suggesting that the foreign body reaction proceeds in a similar fashion for each of these non-cytotoxic, polymeric biomaterials with varying surface chemistries.</p> / Dissertation

The main question that this thesis addresses is what is the optimal way of producing tissue grown in the peritoneal cavity around a foreign body for its use as a vascular graft? It is known that a foreign body implanted into the peritoneal cavity induces an inflammatory response with cells recruited from within the peritoneal cavity to encapsulate the foreign body. Over the course of two to three weeks these cells produce an organised matrix and differentiate to become myofibroblasts. Tubes of these ‗tissue capsules‘ have been transplanted into the arterial vasculature in several animal models where the tissue capsule differentiates into an arterial structure. This structure consists of a layer of smooth muscle-like cells, adventitia of dense connective tissue including vasa-vasorum and an endothelial layer of flattened mesothelial cells. In order to determine whether the tissue would further differentiate ex vivo in response to mechanical stimulus an in-vitro bioreactor system was built to house tissue capsules produced in a variety of animal models. This bioreactor system could house 4 tissue capsules under physiological conditions including standard pulse rates, pressures and temperatures experienced by an artery. Boiled blood clot (BBC) scaffolds were implanted into the peritoneal cavity of rats to produce tissue capsules. After two weeks of development in the peritoneal cavity, tissue capsules were harvested and implanted into the bioreactor. Tissue capsules grafted into the bioreactor were subjected to mechanical force for a range of time-points, pressure, pulse and flow rates. When analysing tissue immunohistochemically, elastin, myosin, αSMA and desmin were detected. This staining was not consistent across all samples and only present in small parts of some tissue tested. Western analysis did not show any expression of αSMA or myosin. Finally the morphology of the tissue also resembled that of tissue previously implanted into the arterial circulation, but development of mechanical properties were not to the extent that would make the tissue useful as a vascular graft. The bioreactor system was thus modified to be able to house tissue for a period of 3 weeks. This system successfully housed tissue capsules under mechanical force in physiological ranges. Next, a range of materials were tested for their ability to be included into the peritoneal implant device used for the large animal model. Elasteon 80A did not produce any cellular growth or peritoneal pathology in all implanted samples (n = 4). Cloisite, a pro-inflammatory material produced large tissue capsule development over a 2 week implant period in 25% of samples however this tissue was heavily adhered to the greater omentum and dependent on its vascular supply. This data suggested that Elasteon could be used to coat the outer surface of a peritoneal implant device to decrease the rate of peritoneal adhesions. Three devices were designed and fabricated for their use in generating tissue for the modified Mitrofanoff procedure which requires a length of tissue to be implanted between the umbilicus and the bladder as a fistula. In all three cases no implantable material was produced that could be used for this procedure. To modify the device that could be used to produce tissue for any surgical application, a range of devices was produced and the animal model was changed to pigs. Materials incorporated into these devices include Dexon mesh and polyethylene. These devices also did not produce any tissue that could possibly be used as a vascular graft. A novel material, polymer BD347 was then produced for use in developing tissue within the interior of the device to provide greater growth and mechanical properties for developing a vascular graft. In toxicological studies, the replacement rate of cells was unaffected after seven days of incubation of fibroblasts at confluence with the polymer. A range of mechanical properties from pig vasculature was gained so that a sheet of polymer with similar properties to that of a vascular graft could be made. This polymer was fabricated as a tube and implanted into the peritoneal cavity of rats. The implanted polymer remained free-floating with a capsule of tissue in 78% of cases. A device was designed that has the ability to impart a physiological pulsation force on the developing tissue capsule in the peritoneal cavity using a sheep model. When two devices were implanted for a period of 10 days in each animal these devices produced no complications for the animal. Upon harvest all devices were free of adhesion and did not cause any peritoneal or dermal infection. In 100% of cases this device produced tissue that was thick and consistent along the length of the implant. The quality of tissue differed greatly macroscopically between tissue produced around pulsing and non-pulsing scaffolds, but microscopically the structure of both tissues was not significantly different. Approximately 90% of cells in this tissue stained positively for CD45. Tissue in pulsing devices produced a higher amount of vimentin expression in CD45 positive staining cells than tissue in non-pulsing devices. Mechanical properties of tissue in pulsed devices were also much greater than tissue in non-pulsed devices. Two of the pulsed tissues were grafted into the carotid artery of sheep as arterial patches. In one animal tissue lasted a period of 1 week before it ruptured. In the second animal tissue lasted a period of 2 weeks at which time the animal was sacrificed. In this sheep a layer of endothelial cells had migrated to populate areas of the tissue patch. Pulsation of the implant device enhanced the development of tissue capsule in the peritoneal cavity towards arterial properties. These studies provide information on the materials and designs required to produce peritoneal-derived tissue capsules that can be used in a range of surgical applications. These studies also provide information on how this tissue responds to mechanical force and provides an in vitro system for testing this tissue. This work in this thesis has produced a device that is in the stage of pre-clinical development to be used as a potential therapy for cardiovascular disease. This device is a novel development from previous devices used for generating tissue capsules for engraftment and is a significant contribution to work in developing a replacement artery.

Persistent lip swelling can be a diagnostic challenge. We report an unusual case of lip edema in the setting of lip surgery 30 years before presentation and because of retained foreign material. This case highlights the importance of accurate historical information and aggressive diagnostic methods in assessing persistent lip swelling.