Thesis (MAppSc in Physiotherapy)--University of South Australia, 1995

Thesis (Ph.D.)--University of Western Australia, 2006.

Thesis (M.Sc.). / Written for the Dept. of Epidemiology and Biostatistics. Title from title page of PDF (viewed 2008/05/14). Includes bibliographical references.

Thesis--Wisconsin. / Vita. Includes bibliographical references.

Thesis (doctoral)--Rijksuniversiteit te Groningen.

Thesis (M.S.)--University of Wisconsin--Madison, 1984. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 12-13).

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2009. / Title from title screen (site viewed January 12, 2010). PDF text: v, 128 p. : ill. ; 1 Mb. UMI publication number: AAT 3360500. Includes bibliographical references. Also available in microfilm and microfiche formats.

Three longitudinal pulmonary function data sets were analyzed by several statistical methods for the purposes of: 1) determining to what degree the conclusions of an analysis for a given data set are method dependent; 2) assessing the properties of each method across the different data sets; 3) studying the correlates of FEV₁ decline including physical, behavioral, and respiratory factors, as well as city of residence and type of work. 4) assessing the appropriateness of modelling the standard linear relationship of FEV₁ with time and providing alternative approaches; 5) describing longitudinal change in various lung function variables, apart from FEV₁. The three data sets were comprised of (1) yearly data on 141 veterans with mild chronic bronchitis, taken at three Canadian centres, for a maximum of 23 years of follow-up; their mean age at the start of the study was 49 years (s.d.=9) and only 10.6% were nonsmokers during the follow-up; (2) retrospective data on 384 coal workers categorized into four groups according to vital status (dead or alive) and smoking behavior, with irregular follow-up intervals ranging from 2 to 12 measurements per individual over a period of 9 to 30 years; (3) a relatively balanced data set on 269 grain workers and a control group of 58 civic workers, which consisted of 3 to 4 measurements taken over an average follow-up of 9 years. Their mean age at first measurement was 37 years (s.d.=10) and 53.2% of the subjects did not smoke. A review of the pulmonary and statistical literature was carried out to identify methods of analysis which had been applied to calculate annual change in FEV₁. Five methods chosen for the data analyses were variants of ordinary least squares approaches. The other four methods were based on the use of transformations, weighted least squares, or covariance structure models using generalized least squares approaches. For the coal workers, the groups that were alive at the time of ascertainment had significantly smaller average FEV₁ declines than the deceased groups. Post-retirement decline in FEV₁ was shown by one statistical method to significantly increase for coal workers who smoked, while a significant decrease was observed for nonsmokers. Veterans from Winnipeg consistently showed the lowest decline estimates in comparison to Halifax and Toronto; recorded air pollution measurements were found to be the lowest for Winnipeg, while no significant differences in smoking behavior were found between the veterans of each city. The data set of grain workers proved most ameniable to all the different analytical techniques, which were consistent in showing no significant differences in FEV₁ decline between the grain and civic workers groups and the lowest magnitude of FEV₁ decline. It was shown that quadratic and allometric analyses provided additional information to the linear description of FEV₁ decline, particularly for the study of pulmonary decline among older or exposed populations over an extended period of time. Whether the various initial lung function variables were each predictive of later decline was dependent on whether absolute or percentage decline was evaluated. The pattern of change in these lung function measures over time showed group differences suggestive of different physiological responses. Although estimates of FEV₁ decline were similar between the various methods, the magnitude and relative order of the different groups and the statistical significance of the observed inter-group comparisons were method-dependent No single method was optimal for analysis of all three data sets. The reliance on only one model, and one type of lung function measurement to describe the data, as is commonly found in the pulmonary literature, could lead to a false interpretation of the result Thus a comparative approach, using more than one justifiable model for analysis is recommended, especially in the usual circumstances where missing data or irregular follow-up times create imbalance in the longitudinal data set. / Graduate and Postdoctoral Studies / Graduate

Laboratory serum biochemical tests are regarded by the Liver Study Group (LSG) of the WSAVA as an essential component of any liver investigation. The LSG categorised liver disease into four groups: vascular disorders, biliary disorders; parenchymal disorders and neoplasia. The laboratory tests that evaluate the liver have three categories. The cytosolic enzymes assess hepatocellular integrity; the cholestatic or inducible enzymes assess the biliary tree, liver excretory pathways and possible enzyme induction. The third category is the liver function tests which assess overall hepatic functional mass and portovascular integrity. The liver function tests commonly used include plasma ammonia concentration, serum bile acid concentrations and various tests that evaluate the uptake and conjugation of metabolites by the liver. Uric acid was once used as a liver test in the late 1950’s early 1960’s. Physiologically, uric acid is an attractive candidate for a liver function test. In most mammalian species serum uric acid levels only increase to the levels encountered in humans when there is hepatic dysfunction. Uric acid fell out of favour as a liver function test following the publication of two studies and one case report in the late 1950’s. The differences between hepatocellular integrity tests, cholestatic tests and tests of liver function were not fully understood at that time. The authors unfairly compared uric acid, essentially a liver function test, to a test of cholestasis. In addition the authors had very vague inclusion criteria for their liver disease cases. Despite the short-comings in these studies several prominent reference texts have since perpetuated their findings and uric acid fell out of the reckoning as a test of liver function. Many tests of liver function have been used over the years. Dynamic function tests have gained popularity again. Plasma ammonia concentration is a very reliable test of liver function but has very stringent sample-handling requirements which often make its application in the average clinic setting impractical. Serum bile acid concentrations, while not as sensitive or specific for portovascular shunting as ammonia, are widely regarded as the best test of overall liver function, especially with respect to non vascular-associated liver disease. However bile acid assays are not widely available in South Africa resulting in delays in turn-around times. In today’s climate of ever increasing costs, and demand for rapid turn around times, it would be very useful to veterinarians if a simple, rapid, cheap and robust assay could be found for evaluating functional hepatic mass. Uric acid would seem to have this potential and it is performed by most medical laboratories. In this study the serum uric acid concentrations and concentration of bile acids of a control group of normal dogs was used to compare to those in three other groups of dogs. Two of these groups had liver disease, and the third was a renal disease group. The one group of liver disease was comprised of dogs with congenital vascular anomalies while the second liver disease group was made up of dogs with various parenchymal liver diseases. Serum bile acid concentrations in the four groups were compared to the serum uric acid levels to assess the utility of uric acid as a test of liver function; and to measure the affects of diminished renal function on serum uric acid concentrations. There were significant differences in the serum bile acid concentrations between the two liver disease groups and the non-liver disease groups. Uric acid concentrations between all four groups did not differ significantly however. Serum uric acid was elevated in dogs with renal impairment. Therefore the findings in this study indicate that uric acid cannot be used as a test of liver function and is not comparable to serum bile acids in this regard. Copyright / Dissertation (MMedVet)--University of Pretoria, 2009. / Companion Animal Clinical Studies / unrestricted

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