Browsing by Subject "Fatty acids"

Now showing 1 - 4 of 4
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    Effects of dietary fat and omega-3 fatty acids on eicosanoids, endogenous sex hormones and the insulin-like growth factor pathway
    (2010-06) Orr, Lindsay Rae
    This dissertation details a clinical trial that investigated the effects of three controlled, 8-week duration test diets: a high fat diet (HF; 40% of energy from fat), a low fat diet (LF; 20% of energy from fat), and a low fat diet high in omega-3 (n-3) fatty acids (LFn3; 23% energy from fat including 3% of energy from n-3 fatty acids) on breast cancer risk markers including plasma and urinary sex hormones, urinary eicosanoids, and insulin-like growth factor (IGF) pathway endpoints in postmenopausal women. Chapter 1 contains a review of the literature providing context for the clinical trial. Chapter 2 describes the effects of the three test diets on plasma phospholipid fatty acids (PLFA), urinary eicosanoids, and plasma sex hormones. The LFn3 diet significantly increased plasma n-3 PLFA and the HF diet significantly increased estradiol and urinary eicosanoids. These results indicate that high fat diet increases breast cancer risk markers, but are inconclusive with respect to n-3 fatty acids. Chapter 3 describes the effect of the three test diets on urinary sex hormones and metabolites. Urinary excretion of estrone was significantly greater after the LF and LFn3 compared to the HF; however in the context of all the urinary hormones and metabolites measured, this indicates that no clinically significant alterations were observed following the test diets. Chapter 4 details the effects of the test diets on IGF pathway endpoints. LFn3 increased IGF-I and IGF binding protein-3 (IGFBP-3) and the LF increased IGFBP-3. These results indicate that low fat diet may reduce free IGF-I while the addition of n-3 fatty acids to the low fat diet may increase free IGF-I concentrations. The impact on breast cancer risk mediated by the increase in IGF-I with the LFn3 is unknown, but an increase in circulating IGF-I may have an impact on reducing the effects of aging. In conclusion, the test diets had pronounced effects on PLFA but modest effects on plasma and urinary sex hormones. The LFn3 unexpectedly increased IGF-I concentrations, which may demonstrate a role of n-3 in preventing the effects of aging.
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    The fatty acids - inflammation relationship across the lifecycle
    (2011-10) Wang, Huifen
    Dietary fatty acid intake, reflected by the endogenous fatty acid profile, has been associated with the pathogenesis and progression of cardiovascular diseases (CVD). Additional evidence is needed about the specific roles of individual fatty acids in the pathogenesis of inflammation, which is closely linked to CVD risk factors and interwined with oxidative stress and hemostatic dysfunction. It is also important to explore such relationships across the lifecycle. This dissertation, which includes four manuscripts, investigates the relations between fatty acids, biomarkers of inflammation (and oxidative stress and hemostasis), and cardiovascular health among different age groups. Specifically, the influences of adiposity and a genetic variant on the fatty acid/inflammation relations were also explored. The first manuscript used data from a study of obesity, insulin resistance and CVD risk factors in adolescents. A cross-sectional analysis was conducted to examine whether overweight status modified the relations between serum phospholipid fatty acids from dairy fats (i.e. 15:0 and 17:0 fatty acids) and inflammation/oxidative stress among adolescents with a mean age of 15 years. Inverse associations were found between dairy fatty acids and three biomarkers of inflammation and oxidative stress among overweight adolescents, but not their normal weight counterparts. In additional analyses, we further examined the same study question on other fatty acids and observed similar effect modification of adiposity. Only in overweight adolescents, but not in normal adolescents, 18:0 and 20:3ù6 fatty acids were positively, while 20:4ù6 and 22:6ù3 fatty acids were inversely, related to inflammation/oxidative stress. The second manuscript examined whether the cross-sectional relations between dietary intakes of polyunsaturated fatty acids (PUFA) and inflammation differed by genetic variant, peroxisome proliferator-activated receptor gamma (PPARã) Pro12Ala polymorphism. A biracial cohort of middle-aged adults enrolled in the year-20 exam of the Coronary Artery Risk Development in Young Adults (CARDIA) study was studied. In women, higher dietary intakes of 20:4ù6, 20:5ù3 and 22:6ù3 fatty acids were related to lower levels of IL-6 (an inflammatory biomarker) among Ala allele carriers. In contrast, these PUFA/IL-6 relations were positive among male Ala carriers, and absent among female Pro homozygotes. Male Pro homozygotes who consumed more 20:5ù3 and 22:6ù3 fatty acids tended to have a lower IL-6 level. The last two manuscripts were both prospective studies using data from the Atherosclerosis Risk in Communities (ARIC) study, which enrolled middle-aged adults. This cohort has been followed since year 1987-89. Manuscript 3 examined the interactions between dietary fatty acid intake and inflammatory/hemostatic factors in relation to incident coronary heart disease (CHD) and ischemic stroke (IS). Dietary intakes of 18:2ù6 and 20:4ù6 fatty acids were found to modify the associations between serum albumin and incident CHD/IS. The prediction of low serum albumin level, a potential inflammatory biomarker, on incident CHD/IS was attenuated with increasing intake of 18:2ù6 fatty acid or decreasing intake of 20:4ù6 fatty acid. Manuscript 4 included 3,715 ARIC participants enrolled at the Minnesota field center who had plasma phospholipid fatty acid measurements. In manuscript 4, the focuse was to determine whether inflammation/hemostasis mediated the relation of phospholipid fatty acids with incident CHD and IS. Inflammation and hemostasis, represented by levels of factor VIIIc (VIIIc), white blood cell count (WBC) and fibrinogen, mediated the positive associations of 18:0 and 20:3ù6 fatty acids with incident CHD. A similar but less significant pattern was found for 16:1ù7 in relation to incident IS. Lower WBC, but not VIIIc or fibrinogen, partially explained the inverse relations of 17:0 and 20:4ù6 fatty acids with incident CHD. In conclusion, this dissertation documents the associations between diverse fatty acids, inflammation and the development of CVD among different age-groups. The findings have enhanced the understanding of the health effects of individual fatty acids and the underlying mechanisms of fatty acid-inflammation-CVD relations, which are useful for advising food manufacturers and guiding CVD prevention.
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    Feeding strategies during the nursery phase of dairy calves to promote increased gastrointestinal development efficiency and reduced weaning costs
    (2014-07) LaBerge, Rebekah
    Neonatal dairy calf nutritional strategies are constantly manipulated and explored as gastrointestinal development, growth, health, and cost are considered. Functional food incorporation is becoming increasingly important to eliminate fed antimicrobials. Alternative protein use is continuously research as competition for whey proteins increases. All programs need to result in the healthiest and well-grown calf possible, with a well-developed ruminant system before weaning, achieved by grain intake. These three studies investigate achieving these goals. Whey cream replacing a portion of conventional milk replacer (22% protein, 20% fat, DM basis) was successful with some tendencies for growth and health. The large amount (4% of BW) of high starch starter (38%) consumed by harvested calves showed signs of mild to moderate acidosis and gastrointestinal inflammation. A study replacing 5% of 22% whey protein with soy isolate led to similar performance and health when fed at a step-up method. A study comparing the interaction of medium chain fatty acids (MCFA) on the plane of nutrition with an accelerated (28% protein, 21% fat, DM basis), resulted in most benefits with MCFA was combined with a high plane of nutrition. Although starter intake was greater for the low plane of nutrition, high plane of nutrition had increased body weight gain because energy intake between the treatments was not similar until week 6 of life. Harvested calves in this study (week 3) yielded interesting results about when maturation of the gut may begin in relationship to grain intake.
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    Thermo-activated drug release.
    (2010-09) Zeng, Pengyun
    Inhalation is an effective means of drug administration for treatment of respiratory diseases. Development of a respirable, stimuli-responsive aerosol formulation would further enhance the drug delivery efficiency. In this thesis, it is postulated that a magnetite/lipid formulation stimulated by alternating magnetic fields can be adapted for use as a thermal-activated delivery system to achieve the desired dose and temporal control of drug release. To test this hypothesis, the following specific aims were carried out: (1) Determine the thermal response of superparamagnetic nanoparticles (SPNs) to alternating magnetic fields, (2) Evaluate the release of solute from temperature sensitive aerosol particles, (3) Assess magnetic-activated release of drug from a lipid matrix, and (4) Study the feasibility of magnetic-activated release of solutes with varying polarity from lipid particles. SPNs heat production was found to be quantitatively consistent with theory, and incorporation of SPNs into solid lipid matrices allowed magnetic heating. For the second aim, thermal activation was shown to be necessary and sufficient for the release of encapsulated solute using naturally occurring lipids. For the third aim, stimuli sensitive release of a test solute was demonstrated, which coincided with melting of the matrix. As such, "on-off" drug release was shown to be controlled by a magnetic field. The release was diffusion controlled, such that existing transport theory can be used to guide the development of delivery systems with appropriate release characteristics. Finally, solid lipid particles containing test compounds were characterized and assessed in vitro for thermal and magnetic stimuli release. Surface release and particle erosion mechanism were suggested for nanoparticles containing a hydrophobic compound. For the release from microparticles, magnetic activation was observed in microscopic images. Magnetic activated release was detected for core-lipid shell particles containing a hydrophilic solute, which may be a consequence of physical rotation of the SPNs. A quantitative framework was established to judge the feasibility of developing a magnetic-sensitive drug delivery system that is also respirable. In light of this analysis, significant practical challenges were revealed that make this approach impractical with currently available technology.