Browsing by Subject "lipoproteins"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
Item Effects of a High Oleic Acid Beef Diet on Cardiovascular Disease Risk Factors of Human Subjects(2012-10-19) Adams, Thaddeus HunterThe consumption of high-fat hamburger enriched with saturated fatty acids (SFA) and trans-fatty acids (TFA) may increase risk factors for cardiovascular disease, whereas hamburger enriched with monounsaturated fatty acids (MUFA) may have the opposite effect. Ten mildly hypercholesterolemic men consumed five, 114-g hamburger patties per week for two consecutive phases. Participants consumed low-MUFA (high SFA) hamburger (MUFA:SFA = 0.95; produced from pasture-fed cattle) for 5 wk, consumed their habitual diets for 3 wk, and then consumed high-MUFA hamburger (MUFA:SFA = 1.31; produced from grain-fed cattle) for 5 wk. These MUFA:SFA were typical of ranges observed for retail ground beef. Relative to habitual levels and levels during the high-MUFA phase, the low-MUFA hamburger: increased plasma palmitic acid, palmitoleic acid, and triacylglycerols (P < 0.01); decreased HDL cholesterol (HDL-C) and LDL particle diameter percentile distributions (P < 0.05); and had no effect on LDL-C or plasma glucose (P > 0.10). Plasma palmitoleic acid was positively correlated with triacylglycerols (r = 0.90), VLDL-C (r = 0.73), and the LDL:HDL (r = 0.45), and was negatively correlated with plasma HDL-C (r = -0.58), whereas plasma palmitic, stearic, and oleic acid were negatively correlated with LDL particle diameter (all P <= 0.05). Because plasma palmitoleic acid was derived from [delta]9 desaturation of palmitic acid in the liver, we conclude that alterations in hepatic stearoyl-CoA desaturase activity may have been responsible for the variation in HDL-C and triacylglycerols caused by the low-MUFA and high-MUFA hamburgers. Cattle with a genetic predisposition to deposit MUFA in their lean and fat tissues, such as Wagyu cattle can be used to produce beef products that are especially enriched with oleic acid and lower in SFA and TFA, and feeding practices can further enhance the composition of beef fat. This indicates that ground beef or hamburger products can be produced that are naturally enriched with oleic acid, and conversely that certain production practices can impair the nutritional quality of beef fat. Finally, we cannot discern from this study design whether the high-MUFA hamburger reversed the effects of the low-MUFA hamburger, or whether the subjects gradually adapted to the elevated intake of total fat. It is clear, however, that the high-MUFA hamburger did not exacerbate any of the effects of the low-MUFA hamburger and can be viewed as at least neutral in its effects on HDL-C and triacylglycerols.Item Genetic and dietary effects on the physical properties, assembly and secretion of apoB-containing lipoproteins(Texas A&M University, 2005-11-01) Wang, LiminThe physical properties (i.e., mass, particle diameter and composition) of apolipoprotein B (apoB)-containing lipoproteins (apoB-LP) are a major determinant of atherosclerotic cardiovascular disease (ASCVD) risk. The objective of this research was to investigate how nascent apoB-LP physical properties affect circulating lipoprotein profiles and risk of disease. Relationships between apoB-LP physical properties and arterial plaque formation in four genotypes of mice with apoB isoform specific clearance defects were investigated. Multivariate statistical analysis found that arterial lesions were most closely related to genetic background and apoB concentration related to delayed clearance rate. For defining the dietary effects on circulating lipoprotein profiles, the physical properties of lipoproteins in hamsters fed high-carbohydrate diets containing either 60% fructose or 60% cornstarch for 2 wk were studied. Fructose increased very low-density lipoprotein (VLDL) particle diameter and decreased low-density lipoprotein (LDL) particle diameter. Elevations in all high-density lipoprotein (HDL) fractions were observed in the fructose-fed group. Further investigation was made of whether changes to the physical properties in circulating lipoproteins resulted from changes to nascent particles in the assembly and secretion processes. Intermediate particles used for lipoprotein assembly were isolated from rough endoplasmic reticulum of hamster liver, and nascent VLDL were isolated from plasma after Triton WR-1339 injection of hamsters. A large, TG-rich apoB-deficient particle and a small, lipid-poor apoB-containing particle were isolated in each dietary setting. The diameter of first-step particles was larger in fructose feeding, which indicated that apoB degradation decreases and provides the basis for apoB oversecretion. Fructose feeding significantly increased the concentrations recovered from liver for these two particles and for nascent particles compared with chow or starch feeding. Collectively, these results demonstrate: 1) genetic factors can dictate metabolism, and metabolic conditions can critically affect the physical properties and further atherogenicity of apoB-LP; 2) changes in physical properties of circulating apoB-LP are derived from changes to the nascent particles; and 3) dietary factors can influence the assembly, secretion, and metabolism of apoB-LP. The findings of the research may provide a metabolic basis for the recognition of new targets that could regulate apoB-LP metabolism to prevent and treat ASCVD.