No description available.

Stuttgart, Univ., Diss., 2005.

Ten polymethylmethacrylate (PMMA) beads containing metronidazole (3 concentrations); gentamicin sulfate; or metronidazole and gentamicin sulfate were immersed in 5 ml of phosphate buffered saline in triplicate. Eluent was replaced at specified time intervals for 1 day (1, 3, 6, 12 and 24 hours), daily, or weekly for 21 days. Antibiotic concentrations were measured by high performance liquid chromatography. Changes in antibiotic bioactivity attributable to polymerization or co-polymerization of the antibiotics with PMMA, ethylene oxide sterilization, and storage of antibiotic-impregnated PMMA (AIPMMA) beads containing metronidazole were evaluated. Antibiotic elution patterns were similar for all groups. Day-1 elution for groups containing either metronidazole (3 concentrations) or gentamicin represented a mean 63% to 66% and 79% respectively of the 21-day total elution. Approximately 50% of the day-1 elution occurred during the first hour. The elution of metronidazole was dose-dependent. There was no significant difference in the total amount of antibiotic eluted from groups that had the saline changed daily versus weekly. The elution of metronidazole (day 3-21) and gentamicin (all days) was significantly greater when metronidazole and gentamicin were combined (p<0.05). Polymerization of PMMA was delayed in groups containing metronidazole. Neither polymerization nor co-polymerization of metronidazole and gentamicin with PMMA, gas-sterilization, or 2-month storage of beads containing metronidazole significantly affected antimicrobial bioactivity. Metronidazole elutes from PMMA. The frequency at which the saline was changed did not affect the rate of antibiotic elution. Co-polymerization of metronidazole and gentamicin sulfate in PMMA resulted in increased rates of elution. Intra-operative preparation of metronidazole-impregnated PMMA beads is not practical. However, prefabrication of metronidazole or metronidazole-gentamicin beads, gas-sterilization and storage for up to 2 months should not affect the efficacy of either antibiotic. The local delivery of biologically active metronidazole and gentamicin by elution from PMMA is feasible. / Master of Science

Amikacin-, vancomycin- or amikacin/clindamycin-impregnated gel was placed subcutaneously on either side of horses' necks a total of 6 times each. Interstitial fluid was collected at 0, 4, 8, 12 and 24 hours, and days 2 through 10, via capillary ultrafiltration probes placed within the incision (0cm) and 1.5cm laterally. Plasma or serum was collected at days 0, 1 and 7. Biopsy samples were obtained at the completion of the study. A histomorphologic score was assigned to each sample, and the differences in mean scores between treatment (gel) and control incisions were assessed using Wilcoxon signed rank test. Amikacin and vancomycin samples were analyzed via fluorescence polarization immunoassay; clindamycin samples were analyzed via high performance liquid chromatography. Concentrations greater than 2000 times the MIC of vancomycin and clindamycin, greater than 1000 times the MIC of amikacin, and greater than 800 times the MIC of amikacin (amikacin/clindamycin gel) were obtained at 0cm. Mean concentrations remained above MIC for vancomycin and clindamycin for 10 days (0cm) and 8 days (1.5cm); for 9 days (0cm) and 7 days (1.5cm) for amikacin gel; and for 9 days (0cm) and 5 days (1.5cm) for amikacin (amikacin/clindamycin gel). Mean plasma amikacin and vancomycin concentrations were negligible; serum clindamycin concentrations were greater than MIC (0.52µg/ml and 0.63µg/ml) at 24 hours and 7 days respectively. There were no significant differences in histomorphologic scores between treatment and control incisions. Cross-linked dextran gel is a safe, effective alternative for local antibiotic delivery in horses, with substantially high local concentrations and minimal systemic absorption for amikacin- and vancomycin-impregnated gels. / Master of Science

Master of Science / Department of Clinical Sciences / Walter C. Renberg / Objective: To compare the in vitro elution characteristics of six common analgesic medications from a commercially available absorbable gelatin sponge. Study Design: Experimental study. Methods: Gelatin sponges were loaded with various analgesic medications, including two opioids, preservative-free morphine and fentanyl, two local anesthestics, bupivacaine and lidocaine, and two α2-adrenergic agonists, dexmedetomidine and xylazine. The loaded sponges were placed in dishes containing phosphate-buffered saline (PBS) and maintained at 37° C with constant agitation. Concentrations of each drug were determined at various time points up to 24 hours post-inoculation using high-pressure liquid chromatography. Two phases were conducted, utilizing undried loaded sponges (phase one) and dried loaded sponges (phase two). Results: In both phases, all analgesic medications eluted from the gelatin sponge and equilibrated rapidly with the PBS, achieving maximal concentration within 30 minutes. In phase two, the rapid nature of the release was captured by increasing sampling within the initial 30 minutes. Results were consistent for each medication with minimal variation. Steady state concentrations were significantly higher in phase two with four out of six medications. Conclusions: Analgesic medication elution from an absorbable gelatin sponge was rapid and consistent. Drying the loaded sponge prior to use will likely substantially increase the amount of medication eluted but not prolong release. Clinical Relevance: The rapid release of analgesic medications from the gelatin sponge makes a prolonged analgesic effect unlikely without further modification. Toxicity may be a concern. Further study is required to investigate efficacy in vivo, safe dosing regimens and prolongation of duration of action.

Waterborne enteric viruses are transmitted via the fecal-oral route and have been isolated from various types of water ranging from sewage to tap water. Water matrices characterized by low levels of organic material (e.g. clean surface water and tap water) contain fewer numbers of viruses than sewage and wastewater effluents. A number of methods have been developed to concentrate, elute (recover), and re-concentrate viruses from water. The goal of this dissertation is two-fold. An extensive review of the literature is provided in Appendix A that focuses on method development in the three aforementioned areas. A review of this detail has not been conducted in over two decades, and as such will contribute to the fields of water quality and environmental virology. Second, a novel and inexpensive method for the concentration of viruses (MS2 coliphage, poliovirus 1, echovirus 1, Coxsackievirus B5, and adenovirus 2) is presented in Appendix B. The method uses a new electropositive filter (comprised of nanoalumina fibers) for the capture of viruses from 20-L volumes of dechlorinated tap water. Average filter retention efficiencies for each of the viruses was &ge; 99%. Viruses that are adsorbed to filters must then be recovered (eluted). A number of inorganic solutions were evaluated for this purpose, the most effective being a moderately alkaline (pH 9.3) glycine buffered-polyphosphate solution. Secondary reconcetration of the eluates was performed using an optimized ultrafiltration method (Centricon Plus-70, Millipore, Billerica, MA), and achieved final concentrates volumes of 3.3 ± 0.3 mL. Total method efficiencies meeting the project recovery goal of &ge; 50% were obtained for each of the tested viruses except for MS2 coliphage at high input titers (45 &plusmn; 15%) and adenovirus 2 (14 &plusmn; 4%). Appendix C provides the Standard Operating Procedures, sample calculations, and detailed data for the experiments conducted. Appendix D details the steps taken towards optimizing the secondary concentration procedure in effort to meet the 50% recovery goal.

Biodiesel is rapidly growing as a fuel of interest due to the various advantages it has over conventional diesel fuel. While the pros – non-toxic, biodegradable, low green house gas emissions seem advantageous, the major issue that plagues the use of biodiesel is its cold weather operability. Biodiesel can present challenges in cold-weather operation, because certain of its constituent compounds can form precipitates in the fuel. These precipitates can cause undesired effects like plugging of fuel filters and deposits. This issue has been attributed to the presence of impurities (mostly saturated monoglycerides, di-glycerides, soap etc) in biodiesel and has been discussed in the literature. There is a move by users and standards associations to implement more stringent norms and quality control to avoid problems in the widespread use of biodiesel. This study involves ways to reduce MG’s in biodiesel by mitigating to a greater extent the possibility of side reactions (formation of soap). The effect of selective transesterification of oil as a function of alcohol, temperature and catalyst concentration was also studied. Although saturated MG’s with high melting points are a greater source of deposits, it can be hypothesized that the polymorphic nature of unsaturated Monoglycerides could also be contributing to cold flow issues. It is hence vital to make sure the biodiesel is free from all forms of monoglycerides. It was also seen that there is very little specificity of selection of fatty acid types in the transesterification reaction and that the amount and type of MGs present in the biodiesel is reflected by the relative amount of fatty acids types present in the oil. In biodiesel derived from Canola oil, a preponderance of monoolein was found for all runs. The initial runs carried out as a two stage process using the membrane followed by batch reactor gave very low MG concentrations, well below ASTM standards.

A series of studies on monomer to polymer conversion in adhesive systems was undertaken using micro-Raman spectroscopy. A database of micro-Raman spectra was compiled for identification of tooth tissues and materials. The degree of conversion was assessed as a function of time and light source. Linear and two-dimensional micro- Raman characterisations of the adhesive-dentine and resin-based composite-adhesivedentine interfaces were performed. The degree of monomer to polymer conversion of adhesive systems was correlated with the amount of eluted monomers obtained by highperformance liquid chromatography. The degree of conversion varied significantly depending on adhesive chemical composition, curing time and light source. It was impossible to specify one curing time applicable to all adhesive systems, due to differences in conversion kinetics. In general, conventional halogen light-curing units at twenty seconds curing time produced similar or higher degree of conversion in adhesive systems compared to high-power LED units at ten seconds. Significantly higher monomer conversion was found in the adhesive layer compared to the hybrid layer in both etch-and-rinse and self-etch systems. Etch-and-rinse adhesive systems formed thicker hybrid layers compared to self-etch systems. Micro-Raman spectroscopy gave a more precise indication of dentine demineralisation and adhesive penetration than scanning electron microscopy and indicated that the hybrid layer is a gradual transitional zone between the adhesive layer and un-affected dentine. The absolute amount and weight percent of eluted monomers varied in all tested adhesive systems. In most adhesive systems, more than 90% of eluted monomers were detected within the first one hour of immersion. Overall, no correlation was found between the degree of conversion and the amount of eluted monomers.

ABSTRACT The purpose of this study was to compare the efficiency of three sperm elution methods on sexual assault swabs; factors such as solvent type, solvent volume, sperm concentration, and duration of extraction and elution method were evaluated with respect to observed sperm recovery. Swabs containing dilutions of semen ranging from 1:10 to 1:1,000 and simulated post-coital swabs were extracted via the traditional tube extraction, as well as two direct slide elution techniques, tapping and swirling. For the slide elution techniques, a swab cutting was placed directly onto a microscope slide, a small volume of water or buffer was added, and sperm were eluted by either tapping the sample with a stirring stick or swirling it around the slide with metal forceps. The tube method requires a minimum of one and one half hours for extraction, while the slide elution techniques require only ten seconds for extraction. The average sperm counts from 1:10 dilutions processed with the tapping elution method were statistically higher than the 1:10 dilutions samples processed with tube and swirling methods. Elution by tapping also recovered a significantly higher amount of sperm cells from the 1:1,000 dilution compared to the tube extraction of the same dilution. The tapping elution method consistently resulted in the greatest number of spermatozoa observed, followed by the swirling method and then tube extraction; additionally, incidents of false negatives (no sperm observed) were observed with the tube and swirling methods. Simulated post-coital samples produced similar results to the semen samples; however, vaginal swabs from one donor resulted in an extremely high ratio of exfoliated epithelial cells that obscured the spermatozoa, especially with the direct slide elution methods. The slide elution methods resulted in similar and consistent relative standard deviations between dilutions in samples, while the tube extraction results suggest an increase in variance as the dilution increases. Overall, slide elution methods yielded the most observed sperm cells in a significantly shorter amount of time.

Biodiesel is rapidly growing as a fuel of interest due to the various advantages it has over conventional diesel fuel. While the pros – non-toxic, biodegradable, low green house gas emissions seem advantageous, the major issue that plagues the use of biodiesel is its cold weather operability. Biodiesel can present challenges in cold-weather operation, because certain of its constituent compounds can form precipitates in the fuel. These precipitates can cause undesired effects like plugging of fuel filters and deposits. This issue has been attributed to the presence of impurities (mostly saturated monoglycerides, di-glycerides, soap etc) in biodiesel and has been discussed in the literature. There is a move by users and standards associations to implement more stringent norms and quality control to avoid problems in the widespread use of biodiesel. This study involves ways to reduce MG’s in biodiesel by mitigating to a greater extent the possibility of side reactions (formation of soap). The effect of selective transesterification of oil as a function of alcohol, temperature and catalyst concentration was also studied. Although saturated MG’s with high melting points are a greater source of deposits, it can be hypothesized that the polymorphic nature of unsaturated Monoglycerides could also be contributing to cold flow issues. It is hence vital to make sure the biodiesel is free from all forms of monoglycerides. It was also seen that there is very little specificity of selection of fatty acid types in the transesterification reaction and that the amount and type of MGs present in the biodiesel is reflected by the relative amount of fatty acids types present in the oil. In biodiesel derived from Canola oil, a preponderance of monoolein was found for all runs. The initial runs carried out as a two stage process using the membrane followed by batch reactor gave very low MG concentrations, well below ASTM standards.