Faculty of Engineering, School Process & Materials Engineering, PhD Thesis / If one were to imagine the body as a chemical processing plant, then the liver would be equated to the reactor responsible for almost all the metabolic activities of the body. There is hardly any chemical produced, secreted or regulated that the liver is not directly or indirectly responsible for, making the design of an artificial liver a daunting task for any researcher. It is currently impossible to replicate the multitude of functions of a single liver cell, even given all the knowledge and technological advances of the 21st century. An artificial liver should be able to supplement the failing functions, especially those of a detoxification nature, of an injured or diseased liver. This can be achieved by harnessing the natural capabilities of transformed hepatocytes for use in a hybrid artificial liver. Today, even with all the research currently taking place, liver transplantation is still the most common response to acute or chronic liver failure. The aim of this study was to develop a feasible theoretical design for a hybrid artificial liver reactor. This study draws on various disciplines such as biochemistry, medicine and engineering. A high-level systems approach was employed to the Process Synthesis. Process Synthesis methodology ensures efficiency in the design process which is achieved by conducting the laboratory experiments in parallel with the reactor or process design such that only those experiments or parameters that require optimisation need to be performed. The capability of the selected transformed hepatocyte cell lines, HuH7 and HepG2 for specific liver functions; the intrinsic cells kinetics for the two cell lines and the sensitivity of the reactor design to the cell line incorporated were determined. The three liver function tests selected were: ammonia metabolism, lignocaine uptake and 99mTc-DISIDA uptake. Our laboratory data demonstrate that for all three functions, both the cell lines exhibit liver functionality and that their kinetics are fairly similar. This finding suggests that the type of cell line incorporated in the reactor does not appear to significantly impact on the reactor design. Hence, it would appear from the preliminary screening tests that the choice of cell line incorporated is not a key parameter. Since Chang’s method of immuno-isolation by microencapsulation was employed, the kinetics of external mass transfer was compared to the intrinsic cell kinetics to determine the rate-limiting step. Results indicate that the capsular membrane does not significantly impede mass transfer and that intrinsic cell kinetics is the rate-limiting step. The research has demonstrated that a packed bed configuration is a feasible reactor type capable of including the

The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Title from PDF of title page (University of Missouri--Columbia, viewed on September 16, 2009). Thesis advisor: Dr. John Thyfault, Dr. Tom Thomas. Includes bibliographical references.

BACKGROUND: Resolution of the link between micro- and macroevolution calls for comparing both processes on the same deterministic landscape, such as genomic, metabolic or fitness networks. We apply this perspective to the evolution of carotenoid pigmentation that produces spectacular diversity in avian colors and show that basic structural properties of the underlying carotenoid metabolic network are reflected in global patterns of elaboration and diversification in color displays. Birds color themselves by consuming and metabolizing several dietary carotenoids from the environment. Such fundamental dependency on the most upstream external compounds should intrinsically constrain sustained evolutionary elongation of multi-step metabolic pathways needed for color elaboration unless the metabolic network gains robustness - the ability to synthesize the same carotenoid from an additional dietary starting point. RESULTS: We found that gains and losses of metabolic robustness were associated with evolutionary cycles of elaboration and stasis in expressed carotenoids in birds. Lack of metabolic robustness constrained lineage's metabolic explorations to the immediate biochemical vicinity of their ecologically distinct dietary carotenoids, whereas gains of robustness repeatedly resulted in sustained elongation of metabolic pathways on evolutionary time scales and corresponding color elaboration. CONCLUSIONS: The structural link between length and robustness in metabolic pathways may explain periodic convergence of phylogenetically distant and ecologically distinct species in expressed carotenoid pigmentation; account for stasis in carotenoid colors in some ecological lineages; and show how the connectivity of the underlying metabolic network provides a mechanistic link between microevolutionary elaboration and macroevolutionary diversification. REVIEWERS: This article was reviewed by Junhyong Kim, Eugene Koonin, and Fyodor Kondrashov. For complete reports, see the Reviewers' reports section.

published_or_final_version / abstract / Medicine / Master / Master of Philosophy

Metabolic syndrome includes several metabolic and hormonal disorders, such as abdominal obesity, insulin resistance, and lower blood ghrelin. Women with breastfeeding history exhibit a reduced risk for metabolic syndrome in later life. The purpose of aim 1 was to determine the incidence of metabolic syndrome in low income, overweight/obese women in early postpartum and to assess its relationship to lactation status. It has been found that the incidence of metabolic syndrome is much higher in formula feeding women than that of the breastfeeding ones (44.3% vs. 22.4%, p < 0.01). The breastfeeding mothers had reduced triglycerides (109.07 mg/dl vs. 143.10 mg/dl, p < 001) and elevated serum high-density lipoprotein (HDL)-cholesterol (58.59 mg/dl vs. 51.76 mg/dl, p < 0.01). The goal of aim 2 was to explore associations between ghrelin, metabolic syndrome and infant feeding methods in low income, overweight/obese women in early postpartum. In our study, the breastfeeding mothers in early postpartum had higher plasma ghrelin, as compared to those who formula fed (584.73 pg/ml vs. 450.77 pg/ml, p < 0.01). Additionally, it is found that plasma ghrelin was negatively associated with incidence and numbers of risk factors for metabolic syndrome, before and after controlling for body mass index (BMI). After adjusting for ghrelin in logistic regression analyses, significant relationships between lactation status and metabolic syndrome disappeared. Thus, the protective function of breastfeeding against metabolic syndrome in overweight/obese women in early postpartum may related to the plasma ghrelin values. The purpose of aim 3 was to detect the influence of weight loss on insulin resistance and plasma adiponectin, zinc (Zn), manganese (Mn) and copper (Cu) in low income, overweight/obese women in early postpartum. After an eight-week weight loss intervention, plasma levels of adiponectin, Zn and Mn were significantly enhanced, and plasma concentrations of insulin (7.53±0.56 vs. 6.23±0.49, p <0.01) and insulin resistance (1.84±0.15 vs. 1.44±0.12, p <0.01) were reduced. The increase of adiponectin, Zn and Mn was positively associated with weight reduction. However, the plasma Cu was not significantly affected. The relationships between weight loss and reduced insulin resistance disappeared after adjusting the increases of adiponectin, Zn and Mn during weight loss. Thus, weight loss had beneficial effects on insulin resistance, plasma values of adiponectin Zn and Mn. It is plausible that the influence of weight loss on insulin resistance may be associated with improvements of plasma of adiponectin, Zn and Mn. Collectively, the results of this study demonstrate the important benefits of breastfeeding on prevention of metabolic syndrome in overweight/obese women in early postpartum. This study also emphasizes the influence of ghrelin on risk factors of metabolic syndrome and lactation status. / text

In this work, a differential biofiltration reactor was used to explore the potential of metabolic uncouplers to improve pollutant (toluene) degradation rates. Metabolic uncouplers were reported to reduce the cell mass in activated sludge systems, but are untested in biofilters and the current work is the first to report the impact of different metabolic uncouplers in a biofilter. Initially soil was used as a biofilter bed and later experiments were conducted in pure cultures in a biofilm reactor. A simple diffusion system was developed to generate the desired concentration of toluene to the system. Gas chromatography and a carbon dioxide analyzer were connected online to the reactor which improved the precision of the data collected and also the robustness of the measurements. Preliminary experiments including effect of substrate concentration, different nutrients and temperature were done to optimize the conditions before starting the metabolic uncoupler screening studies in soil. Based on the results, inlet toluene concentration between 180 ppm and 250 ppm was used throughout the studies. Also it was found that the toluene degraders were nitrogen limited. Temperature studies showed that the elimination capacity (EC) increased with increasing temperature, from 34 ± 1.4 g.m-3.h-1 to 49.8 ± 2.6 g.m-3.h-1 for temperatures of 20 to 45 oC, respectively. Nine potential metabolic uncouplers were screened in batch serum bottles. The nine uncouplers tested were dinitrophenol (dNP), p-nitrophenol (pNP), benzoic acid (BA), carbonylcyanide p-trifluoromethoxy phenylhydrazone (FCCP), carbonylcyanide m-chloromethoxy phenylhydrazone (CCCP), pentachlorophenol (PCP), malonic acid (MA), m-chlorophenol (mCP) and 2, 4, 6-trichlorophenol (TCP). Other than dNP and pNP (nitrogen containing uncouplers), seven other uncouplers were further tested in the differential biofilter reactor. Only PCP and TCP increased the toluene degradation rate significantly. PCP increased the toluene degradation rate by 35% at 140 µM, whereas 4051 µM TCP increased the rate by 18%. Though FCCP behaved as a classical uncoupler when compared with others, the EC increase was not significant. Five toluene degraders were isolated from soil subjected to toluene and were identified using 16s rDNA/18s rDNA analysis. Out of five, two potential toluene degraders, Stenotrophomonas maltophilia and Pseudomonas putida were used to develop a biofilm reactor. PCP, TCP and CCCP were tested in the biofilm reactors and found that PCP increased the surface elimination capacity (SEC) by 85% at 140 µM in S. maltophilia biofilm reactor and CCCP increased the SEC by 27% at 1 µM in P. putida biofilm reactor. Finally a simple model was developed to calculate the energy uncoupling coefficient for non-growth systems like ours to quantitatively represent the uncoupling mechanism.

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Metabolic syndrome (MetS) represents a cluster of metabolic abnormalities, characterised by the presence of 3 or more of 1) abdominal obesity, 2) insulin resistance, 3) hypertension, 4) dyslipidaemia, and 5) emerging risk factors, such as pro-thrombotic and pro-inflammatory states, which are each independent cardiovascular disease (CVD) risk factors. This clustering of risk factors is reported to increase the odds ratio for cardiovascular and all-cause mortality above the risk associated with the individual components (Wilson, 2004). The precise aetiology of MetS is currently unknown, however an energy-dense diet, particularly high in carbohydrate, and an inactive lifestyle or low fitness may interact with a genetic susceptibility to contribute to the pathophysiology of MetS (Bouchard, 2007). Therefore the purpose of the studies included in this thesis were to determine whether accumulative brisk walking may improve risk factors associated with MetS and whether one single session of brisk walking at a moderate intensity may improve risk factors associated with MetS in middle-aged men at risk of MetS. Study one recruited 85 males aged 38-73 onto a 24-week randomised controlled trial with participants allocated to control (CON), single 30 minute daily brisk walking (SBW) or accumulative 30 minutes of daily brisk walking (ABW; 3×10 min or 2×15 min) groups. Measures included aerobic fitness (OO2max), body composition and selected blood variables. The main findings were that 24 weeks of accumulating 150 min·wk-1 of brisk walking at ~65% HRmax significantly improved insulin sensitivity, which was associated with decreased abdominal adiposity, assessed by waist circumference, and was at least as effective as a single daily session of equal volume in middle-aged men at risk of MetS. Study two investigated the 24-hour effect of walking for 30 minutes at 50% OO2max (30×50%), 30 minutes at 65% OO2max (30×65%) and 60 minutes at 50% OO2max (60×50%) compared to rest (CON) on cardiovascular control, resting metabolism and selected blood variables. The main findings were that a single 30 minute walking session at 50% OO2max favourably improved cardiovascular control, indicated by decreased heart rate and systolic blood pressure, thus decreasing the workload of the heart, whereas increasing the intensity of the walk to 65% OO2max attenuated this effect, while increasing the duration to 60 minutes had no additional effect compared to 30 minutes at 50% OO2max in men at risk of MetS.