Although leukotrienes (LTs) are implicated in the pathogenesis of asthma, it is still unclear which types of cells are of primary importance in their formation in asthmatic lungs. To elucidate the mechanism for the increased LT formation in asthma, we investigated the pulmonary cellular infiltration and LT synthesis by dispersed lung cells from BN rats following allergen challenge. / To enable us to do these studies we have developed improved HPLC methods for the analysis of complex mixtures of eicosanoids in biological samples using binary gradients containing trifluoroacetic acid. Samples containing PGB$ sb2$ (the internal standard), cysteinyl-LTs, LTB$ sb4,$ hydroxyeicosatetraenoic acids (HETEs) and the cyclooxygenase product 12-hydroxy-5,8,10-heptadecatrienoic acid (12-HHTrE) can be analyzed in as little as 20 min. Mixtures which also contain more polar eicosanoids such as lipoxins and omega-oxidation products of LTB$ sb4$ can be analyzed in 40 min. / Ovalbumin (OVA) challenge of sensitized BN rats resulted in a significant influx of neutrophils into the lungs and a significant increase in the synthesis of 5-lipoxygenase products, in particular LTB$ sb4$, by lung cells 6 h after challenge. However, there was little change in the production of cysteinyl-LTs compared with saline challenge. There was a significant eosinophilic infiltration in the lungs 24 h after OVA challenge, but cysteinyl-LT production by lung cells was unaltered at this time suggesting that eosinophils from BN rats are unlikely to be a major site for the formation of these compounds. This was confirmed in experiments with partially purified eosinophils obtained from Sephadex-treated rats. In contrast, cysteinyl-LTs were synthesized in appreciable amounts by alveolar macrophages from BN rats. Administration of rabbit anti-rat PMNL serum abolished the influx of neutrophils into the lungs and appeared to reduce the LTB$ sb4$ synthesis by lung cells. There was a positive correlation between the numbers of neutrophils in the lung and LTB$ sb4$ production by lung cells. In contrast, macrophages were positively associated with cysteinyl-LT production. Exogenous LTB$ sb4$ and 5-oxo-ETE induced infiltration of eosinophils into the lungs and therefore may be responsible for the late phase eosinophilic infiltration in BN rat lungs following allergen challenge.

This thesis addresses the problem of registration, merging and viewing medical images from multiple modalities for stereotactic surgery planning. A technique is presented, using volumetric rendering of tomographic data, to create anatomical perspective projections that can be easily merged with vascular projections. / The geometry of the digital subtraction angiogram (DSA) projection is reproduced by the rendering process to enable registration between the DSA radiograph and the volumetric projection. The viewing parameters are calculated from the location of fiducial markers in the image. Each angiogram is overlayed onto a translucent volumetric projection of computed tomography (CT) or magnetric resonance (MR) data, rendered to give a matched view. / Until recently, rendered medical volumes have been used qualitatively in the diagnostic and surgical planning process. Since the volumetric projections are matched to the DSA images, the complete set of stereotactic surgery planning tools can be used to identify points and measure distances in the rendered images. / A point spread function of the rendering process is derived to establish a theoretical limit on the accuracy of the technique and is verified by experimentation.

The purpose of this study is to develop and test the validity of an algorithm allowing the classification of the decedents as were dying of, died of and died with BC, using administrative data, for the study of service delivery to the terminally ill. / Validation was carried out through a chart review of a sample of BC decedents extracted from a tumor registry. The algorithm was then applied to the decedents of a cohort of women with BC. The three groups were compared for their distributions of age and place of death. / The validation showed an excellent crude agreement (0.96). Of the 3334 deaths, 2293 were classified as were dying of, 142 as died of, and 949 as died with. The comparison of age showed that women who died with were older than women who were dying of. These two groups differed in their distributions of place of death.

The aim of stereotactic radiosurgery is to deliver a high and uniform radiation dose to the target volume and a minimized dose to the surrounding healthy tissue. Various linac-based radiosurgical techniques are used clinically: multiple non-coplanar converging arcs, dynamic arc rotation, and conical rotation. The techniques differ in their beam distribution over the patient's head. / A study of the beam distribution characteristics for the clinical linac-based radiosurgical techniques is presented. Two spiral linac-based radiosurgical techniques are developed: the uniform dose-rate spiral irradiation and the dose-rate-weighted spiral irradiation. Both exhibit the same spiraling beam entry trace over the patient's head; however, they differ in their beam distribution along the spiral. The dose-rate-weighted spiral irradiation provides a uniform beam distribution over the 2pi solid angle available in radiosurgery. / The currently existing techniques and the spiral techniques are then compared using the cumulative dose-volume histogram (CDVH) tools available with the McGill Treatment Planning System (MPS). The dose-rate-weighted spiral technique leads to lower dose inhomogeneities within the target volume and better dose conformity within the target. Moreover, it also encompasses smaller volumes of tissue at all isodose levels with larger differences at low isodose levels. A conclusion is reached that the dose-rate-weighted spiral irradiation technique offers interesting advantages over the currently used clinical linac-based techniques.

The hands-free technique is the indirect transfer of surgical instruments between surgeon(s) and other scrubbed personnel as well as circulating personnel, during which only one person touches the same sharp item at the same time. Items are usually placed in a designated neutral zone, which can be a section of the surgical field or a container, from where they can be retrieved. / Use of the hands-free technique for passing sharp instruments during surgery has been recommended as a work practice by many professional organizations in order to reduce accidents, but its effectiveness has not been adequately studied. This study was designed to determine whether use of the hands-free technique resulted in a decrease in injuries, contaminations and glove tears. / A prospective approach was used. All surgeries performed from the end of October, 1995 to mid-April 1996 at The Providence Medical Center in Seattle, Washington were eligible for inclusion in the study. / In 3,765 of 5,388 (70%) eligible surgeries performed during that five and one/half month period, circulating nurses filled out forms in the operating rooms right after a surgical case, assessing the proportion of passes done where no more than one person touched a sharp instrument at the same time. / In addition to use of the hands-free technique during surgery, type of surgery, length of surgery, bloodloss during surgery, noise levels, emergency status, number of personnel present and time of day, were also recorded. / Results. The hands-free technique was used, as defined, in about 42% of the surgeries. In another 50% of the surgeries it was used half the time or almost never. It was not used at all in 8% of surgeries. An overall injury, contamination and glove tear rate of 3.9% was measured during the study period. / Conclusion. Use of the hands-free technique at The Providence Medical Center during the study period was associated with a reduction in injuries, contaminations and glove tears, in surgeries with more than 100cc blood loss but a similar reduction was not observed when blood loss was less than 100 cc. (Abstract shortened by UMI.)

<p>Unplanned readmissions back to the hospital are a burden financially and a strain on patients and their families, healthcare organizations, and government payers. Readmissions from skilled nursing facilities account for approximately one-fifth of total rehospitalizations. This project uses the Plan, Do, Study, Act (PDSA) cycle to implement an adaptive problem solving plan to determine the root cause of individual unplanned readmissions from skilled nursing facilities back to the hospital. The plan details past readmission administrative data using descriptive statistics, the roles and responsibilities for the collaborative partnership between care sites, the content of adaptive problem solving, and the use of rigorous reflection and review for continuous improvement. The project provides a disruptive patient centered care approach for problem solving the complexities of readmissions to the hospital for healthcare organizations to consider as readmission rates are tied to reimbursement and quality outcomes. </p>

Algorithms for optimization and verification of radiation treatments have been developed. The first one, an active set algorithm for inverse treatment planning employs a conjugate gradient routine for subspace minimization in order to achieve a higher rate of convergence than the widely used constrained steepest descent method at the expense of a negligeable amount of overhead calculations and storage. The active set algorithm is found to be superior to the constrained steepest descent in terms of both its convergence properties and the residual value of the cost functions at termination. The active set approach can significantly accelerate the process of inverse treatment planning by decreasing the number of time consuming dose calculations. / The second algorithm employs a continuous penalty function method to solve approximately a large-scale constrained minimization problem which reflects the goal of sparing healthy tissues as much as possible while delivering the necessary tumorcidal dose. The performance of the continuous penalty function method is optimized by a numerical investigation of a few integration schemes and a pair of weighting functions which influence the performance of the method. Clinical examples are presented that illustrate possible applications of the techniques in the context of multi-objective optimization. / An image correlation based algorithm for automatic registration of pairs of portal images has also been developed. Accounting for both in-plane translations and rotations, the algorithm uses fast-Fourier-transforms and a sequential approach to speed up the registration without degrading the accuracy of the match. The technique has also been applied to the automatic registration of portal images to digitally reconstructed radiographs (DRRs) which have been modified to resemble megavoltage images. The results indicate the feasibility of this approach as a tool for treatment setup verification.

Post-poliomyelitis syndrome (PPS) is a clinical syndrome of new weakness, fatigue, and pain in individuals who have previously recovered from acute paralytic poliomyelitis. The primary objective of this study was to identify factors which predict subsequent PPS. Among patients with prior polio, cases were those with new weakness and fatigue, and controls were those without these complaints. A chart review of 353 patients evaluated at the Montreal Neurological Institute post-polio clinic identified 127 cases and 39 controls. In univariate analyses, significant risk factors for PPS were a greater current age (odds ratio of 1.8 per decade, 95% confidence interval 1.3 to 2.6), a longer time since acute polio (odds ratio of 1.6 per decade, 95% confidence interval 1.1 to 2.3), more weakness at acute polio (odds ratio 1.5, 95% confidence interval 1.1 to 2.0), a recent weight gain (odds ratio 3.8, 95% confidence interval 1.6 to 9.4), muscle pain with exercise (odds ratio 3.8, 95% confidence interval 1.5 to 9.5), muscle pain (odds ratio 2.6, 95% confidence interval 1.3 to 5.5), and joint pain (odds ratio 2.3, 95% confidence interval 1.1 to 5.3). The multivariate analyses revealed that a model containing current age (odds ratio 1.7 per decade, 95% confidence interval 1.1 to 2.6), weakness at acute polio (odds ratio 1.6, 95% confidence interval 1.1 to 2.5), muscle pain with exercise (odds ratio 4.9, 95% confidence interval 1.6 to 15.6), recent weight gain (odds ratio 6.4, 95% confidence interval 2.02 to 20.3), and joint pain (odds ratio 2.33, 95% confidence interval 0.8 to 7.1) was the most effective in predicting who would develop PPS. Age at acute polio, degree of recovery after polio, weakness at best point after polio, physical activity, and sex were not contributing factors.

Current research has focused on visual feedback for the development of virtual surgery. However, little is known about the haptic feedback required for realistic simulation. The forces necessary for the cutting of anatomical tissues were investigated for three surgical scissors: the Mayo dissection scissor, the Metzenbaum dissection scissor and the Iris scissor. Several experiments were completed in conjunction with a surgical doctor to acquire force data for analysis. This work aimed to establish the force-position relationship, find any invariant properties for tissues or scissors, and determine the frequency components present in the force signal as well as the significance of the cutting rate. General trends in the data were discovered, and necessary improvements to the experimental method for the determination of more exact quantitative measures were identified. / In general, both the measurable force magnitude and "texture" differences contribute to the difference in tactile perception between a blank run and a tissue cutting run. This is a low frequency texture, as 99% of the frequency components of the signal are below 5Hz. The force measurements were determined to be independent of the cutting speed for the Mayo and Metzenbaum scissor runs, whereas results for the Iris scissors were inconclusive. The scissor sensitivity while cutting the tissue longitudinally or transversally appears to be a function of both the tissue and the scissor. To further determine the tactile feedback required for simulation, future experiments should account for the "user grip", tissue thickness, tissue moisture content, hand orientation, and innate scissor dynamics. / A database of the collected force and position data has been created on the Internet (Site:http://www.cim.mcgill.ca/&sim;haptic/tissue/data.html). This data allows current force feedback devices, such as the Freedom-7, to determine the feasibility of realistic haptic simulation.

<p> Workers' compensation programs have emerged as among the largest and most important social programs in the United States. Workers' compensation claims in the state of Michigan account for an expenditure of approximately 1.3 billion dollars annually (Michigan Workers' Compensation Agency, 2011. 2011 <i>Annual Report</i>). Back injuries are the most prevalent work-related injury in the United States. Since 2002, such injuries in the baby-boomer generation have increased at a rate of 50% (Toossi, 2005. <i> Labor force projections to 2014: Retiring boomers</i>). The purpose of this study is to describe the personal lived experiences of older (over 55 years old) injured employees as a result of injuring their lower backs at work. The study only examined occupational lower back injuries suffered while assembling automotive parts in the state of Michigan. The study incorporates a qualitative design, specifically an interpretative phenomenological analysis, to focus on the lived experiences of the participants, and underpins the theory of planned behavior to assist with forecasting and understanding the particular behaviors within this population. A four-step data analysis method was used to illustrate and understand the meaning and essence of the lived experience of the injured, older automobile assembler worker.</p>