Browsing by Author "Zaloga, Gary P."

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    Comparative study of the modulation of fructose/sucrose-induced hepatic steatosis by mixed lipid formulations varying in unsaturated fatty acid content
    (Springer (Biomed Central Ltd.), 2015) Siddiqui, Rafat A.; Xu, Zhidong; Harvey, Kevin A.; Pavlina, Thomas M.; Becker, Michael J.; Zaloga, Gary P.; Department of Medicine, IU School of Medicine
    BACKGROUND: Non-alcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease in developed countries. NAFLD encompasses a spectrum of diseases, ranging from hepatic steatosis to non-alcoholic steatohepatitis (NASH), cirrhosis, and liver failure. The etiology of NAFLD remains unclear but is thought to relate to increased fatty acid flux within the liver that results in toxic fatty acid metabolite production. One source of increased fatty acid flux is fructose/sucrose-induced hepatic lipogenesis. Current treatment for NAFLD encompasses dietary modifications. However, little scientific evidence exists on which to base many dietary recommendations, especially the intake of different types of carbohydrates and fats. We hypothesized that lipid mixtures of unsaturated fatty acids would inhibit lipogenesis and subsequent hepatic steatosis induced by high carbohydrate diets. The aim of this study was to examine the effects of different complex mixtures of fatty acids upon the development of fructose/sucrose-induced hepatic steatosis. METHODS: C57BL/6 mice were randomized to normocaloric chow-based diets that varied in the type of carbohydrate (starch, sucrose, fructose). Animals in each carbohydrate group were further randomized to diets that varied in lipid type (no additional lipid, soybean oil, fish oil, olive/soybean oil, macadamia nut oil). These oils were chosen based upon their content of omega-6 polyunsaturated fatty acids, omega-3 polyunsaturated fatty acids, omega-9 monounsaturated fatty acids, or omega-7 monounsaturated fatty acids. Fatty acid flux in the liver was determine by assessing hepatic lipid content (steatosis). We also assessed fatty acid levels in the plasma and liver of the animals, hepatic lipogenesis activity, hepatic stearoyl-CoA-1 desaturase activity, and hepatic elongase activity. RESULTS: Animals consumed similar amounts of the diets and maintained normal body weights throughout the study. Both sucrose and fructose induced hepatic lipogenesis and steatosis, with fructose being more potent. All mixed lipids similarly inhibited steatosis, limiting lipid content to levels found in the control (starch) animals. Lipogenesis and stearoyl-CoA-1 desaturase activity were increased in the sucrose and fructose groups. Levels of these enzymatic processes remained at baseline in all of the lipid groups. CONCLUSION: This is the first study to compare various complex lipid mixtures, based upon dietary oils with different types of long-chain fatty acids, upon development of sucrose/fructose-induced steatosis. Both carbohydrate source and lipid content appear important for the modulation of steatosis. Moderate intake of complex lipids with high unsaturated to saturated fatty acid ratios inhibited both lipogenesis and steatosis.
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    Modulation of endothelial cell integrity and inflammatory activation by commercial lipid emulsions
    (Springer (Biomed Central Ltd.), 2015) Harvey, Kevin A.; Xu, Zhidong; Pavlina, Thomas M.; Zaloga, Gary P.; Siddiqui, Rafat A.; Department of Medicine, IU School of Medicine
    BACKGROUND: Thrombosis and immune dysfunction are two important complications that result from the administration of parenteral nutrition. Endothelial cells within the vasculature are crucial components necessary for maintenance of normal coagulation and immune function. METHODS: We compared the effects of three commercial lipid emulsions (LEs; Intralipid®, ClinOleic® [or Clinolipid®], and Omegaven®) differing in the levels of omega-6 polyunsaturated fatty acids, omega-3 polyunsaturated fatty acids, omega-9 monounsaturated fatty acids, and saturated fatty acids upon endothelial cell fatty acid composition using Gas chromatography, endothelial cell integrity by assessing measurement of apoptosis and necrosis using flow cytometry, endothelial cell inflammatory activation by assessing the induction of ICAM-1 by lipopolysaccharide [LPS]), and transcription factor activation (phosphorylation of NF-κB) using western blot analysis. RESULTS: Gas chromatographic analysis confirmed cellular uptake of the fatty acids within the LEs; furthermore, these fatty acid changes reflected the composition of the oils and egg phosphatides used in the manufacturing of these emulsions. However, the kinetics of fatty acid uptake and processing differed between LEs. Fish oil LE negatively impacted cell viability by doubling the percentage of apoptotic and necrotic cell populations quantified by flow cytometry using Annexin V/Fluorescein and propidium iodide. The soybean oil LE did not alter cell viability, while the olive oil-predominate emulsion improved cell viability. All LEs were capable of suppressing LPS-induced ICAM-1 expression; however, the fish oil LE was more potent than the other emulsions. Fish oil LE supplementation of cells also suppressed LPS-induced phosphorylation of NF-κB, while the soybean oil and olive predominant LE had no effect upon NF-κB phosphorylation. CONCLUSIONS: Lipid emulsions are readily incorporated and stored in the form of triacylglycerols. Soybean oil-based, olive oil-predominant and fish-oil based LEs differentially affected endothelial cell integrity. Importantly, these three LEs were capable of suppressing endothelial cell inflammatory response despite their fatty acid content.
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    Tocopherol and tocotrienol homologs in parenteral lipid emulsions
    (Wiley, 2015-01) Xu, Zhidong; Harvey, Kevin A.; Pavlina, Thomas M.; Zaloga, Gary P.; Siddiqui, Rafat A.; Department of Medicine, IU School of Medicine
    Parenteral lipid emulsions, which are made of oils from plant and fish sources, contain different types of tocopherols and tocotrienols (vitamin E homologs). The amount and types of vitamin E homologs in various lipid emulsions vary considerably and are not completely known. The objective of this analysis was to develop a quantitative method to determine levels of all vitamin E homologs in various lipid emulsions. An HPLC system was used to measure vitamin E homologs using a Pinnacle DB Silica normal phase column and an isocratic, n-hexane:1,4 dioxane (98:2) mobile phase. An optimized protocol was used to report vitamin E homolog concentrations in soybean oil-based (Intralipid®, Ivelip®, Lipofundin® N, Liposyn® III, and Liposyn® II), medium- and long-chain fatty acid-based (Lipofundin®, MCT and Structolipid®), olive oil-based (ClinOleic®), and fish oil-based (Omegaven®) and mixture of these oils-based (SMOFlipid®, Lipidem®) commercial parenteral lipid emulsions. Total content of all vitamin E homologs varied greatly between different emulsions, ranging from 57.9 to 383.9 µg/mL. Tocopherols (α, β, γ, δ) were the predominant vitamin E homologs for all emulsions, with tocotrienol content < 0.3%. In all of the soybean emulsions, except for Lipofundin® N, the predominant vitamin E homolog was γ-tocopherol, which ranged from 57-156 µg/mL. ClinOleic® predominantly contained α-tocopherol (32 µg/mL), whereas α-tocopherol content in Omegaven® was higher than most of the other lipid emulsions (230 µg/mL). PRACTICAL APPLICATIONS: The information on the types and quantity of vitamin E homologs in various lipid emulsions will be extremely useful to physicians and healthcare personnel in selecting appropriate lipid emulsions that are exclusively used in patients with inadequate gastrointestinal function, including hospitalized and critically ill patients. Some emulsions may require vitamin E supplementation in order to meet minimal human requirements.