Determinants and clinical implications of circulating fatty acids in individuals with chronic kidney disease

Patients with chronic kidney disease (CKD) have a high risk of cardiovascular morbidity and mortality. Adding to traditional risk factors, e.g., Framingham risk factors, novel risk factors including inflammation, insulin resistance (IR) and metabolic syndrome (MetS) are being detected in patients with advanced CKD. Previous research demonstrates a promising possibility of improving patient outcomes by dietary manipulation, which could be an essential part of multi-faceted interventions. This thesis tries to increase our understanding of circulating fatty acids as a reflection of dietary intake in patients with CKD, with special emphasis on their clinical determinants and outcome implications. Study 1 identifies fatty acids in serum cholesterol esters and adipose tissue that are adequate biomarkers of habitual intake in CKD. We found that linoleic acid (LA), eicosapentaenoic acid, docosahexaenoic acid, and palmitic acid in serum cholesterol esters and adipose tissue are good indicators of the habitual dietary fat intake in elderly men with CKD. Dietary fish intake reflects well the intake of n-3 polyunsaturated fatty acids (PUFA) of marine origin. Study 2 investigates the implications of circulating essential PUFA, as a reflection of long-term dietary intake, on the inflammatory risk profile and clinical outcome of dialysis patients. LA in plasma phospholipids is inversely associated with interleukin-6 and all-cause mortality in dialysis patients. Associations between n-3 PUFA, inflammation and mortality were not observed. Study 3 investigates clinical determinants and outcome implications of estimated stearoyl-CoA desaturase-1 (SCD-1) activities of the liver and adipose tissue, as indicators of saturated fat intake, in dialysis patients. We found that both hepatic and adipose tissue SCD-1 activity indices independently relate with interleukin-6 and predict mortality in dialysis patients. Study 4 assesses cross-sectional relationships between serum fatty acid patterns, MetS, IR and inflammation in CKD. A serum fatty acid pattern reflecting low LA and high saturated fatty acids strongly associates with MetS, IR and C-reactive protein, while another pattern reflecting high n-3 PUFA is not linked with these risk factors, in two independent cohorts of elderly individuals with CKD

Characterization and genome-scale metabolic modeling of catechol-degrading Pseudomonas fluorescens isolated from a petroleum hydrocarbon-impacted site

Pseudomonas fluorescens is a candidate for efficient petroleum hydrocarbons (PHC) biodegradation. In this work, a P. fluorescens strain was isolated from a local PHC-impacted site. To investigate its PHC biodegradation performance, catechol, an important metabolic intermediate during monoaromatic hydrocarbon biodegradation, was chosen as the sole carbon source. A set of experiments based on a 23 factorial design was undertaken to investigate how nitrate, sulfate, and phosphate ions affect catechol biodegradation by the isolated P. fluorescens strain. The experimental results were subjected to ANOVA. Maximum specific catechol degradation rates (the response) were estimated by a three-parameter logistic model to evaluate bioremediation performance. ANOVA results suggest introducing nitrate ions alone may lead to poorer bioremediation performance, introducing sulfate ions alone does not affect bioremediation performance, but supplementing with nitrate and sulfate ions together can enhance bioremediation performance. P. fluorescens was also shown to survive under sulfur-limited conditions. Injecting phosphate ions also led to better bioremediation performance. To gain extensive and systematic knowledge of P. fluorescens, the first genome-scale metabolic model (GSMM) for P. fluorescens was reconstructed, termed lCW1057. The model was validated by in vitro growth data. The periplasmic compartment was constructed to better represent the proton gradient profile. The reconstructed proton transport chain has a P/O ratio of 11/8. Flux balance analysis (FBA) was performed to simulate the whole-cell metabolic flow. The simulation results suggested the β-ketoadipate pathway is involved in catechol metabolism by P. fluorescens while the uptake of oxygen is mandatory for cleavage of catechol’s aromatic ring. The Entner-Doudoroff (ED) pathway was involved in glycolysis for P. fluorescens. Moreover, nitrates can be used as the terminal electron acceptor to support P. fluorescens growth under anaerobic condition

U.S. Metropolitan Spatial Structure and Employment Growth

This study explores the influence of US metropolitan spatial structure evolution on regional employment growth rate. The first part of this study investigates the evolution of US metropolitan spatial structures from 2000 to 2010. At the macro level, I categorized metropolitan areas (metros) into three groups (i.e., monocentric, polycentric, and coreless) based on the number of employment centers these metros had in 2000 and 2010. At the micro level, I sub-grouped the three macro spatial structure groups into micro-level clusters based on each metro’s rank of employment shares in five sub-metro locations: the main-center, sub-centers, non-center clusters, non-cluster urban areas, and rural areas. The results show that (1) among 361 US metros, over 80 percent of metros remained in their original macro spatial structure type, and (2) less than 10 percent of metros experienced employment decentralization. The second part of this study explores the influence of spatial structure evolution on regional growth rate. At the macro level, a series of two-sample t-tests showed that the group of monocentric metros that remained monocentric had no significant difference in employment growth rate from the group of monocentric metros that evolved to be polycentric. Conversely, the group of polycentric metros that remained polycentric had a higher employment growth rate than the group of polycentric metros that evolved to be monocentric. At the micro level, a regression analysis showed that the initial sub-centers’ employment share had a larger positive effect on regional employment growth rate than the initial main-center employment share, while the change in non-cluster urban areas’ employment share had a larger negative effect on regional employment growth rate than the change in the non-center clusters’ employment share. The main conclusions from this dissertation are that (1) employment decentralization from the main-center to sub-centers increases regional employment growth rate, whereas employment dispersion — employment migration from centers (i.e., main-center and sub-centers) to non-centers (i.e., non-center clusters, non-cluster urban areas, and rural areas) – decreases regional employment growth rate, and (2) metros’ macro and micro spatial structure types were relatively stable over the study period

Scholarship in international technical communication, 1950-1989: a historical study

This thesis is a study of the published scholarship in international technical communication from 1950 to 1989. It provides insight into the four decades\u27 worth of scholarship as well as a resource for the development of present and future scholarship in international technical communication. It attempts to answer the following research questions: What did scholars of international technical communication study in each decade? What are the similarities and differences among the four decades in terms of scholarship in international technical communication? What are the strengths and weaknesses of the relevant scholarship in the four decades? What can we learn from the scholarship in these four decades? To answer these questions, I reviewed articles collected from the main journals and conference proceedings in technical communication published in the United States. I summarized and coded these articles according to their major subjects. Based on my review of this literature, I drew conclusions about the character and value of the published scholarship in international technical communication from 1950 to 1989 --Abstract, page iii