Alcohol-induced fatty liver (steatosis) was believed to result from excessive generation of reducing equivalents from ethanol metabolism, thereby enhancing fat accumulation. Recent findings have revealed a more comple...Alcohol-induced fatty liver (steatosis) was believed to result from excessive generation of reducing equivalents from ethanol metabolism, thereby enhancing fat accumulation. Recent findings have revealed a more complex picture in which ethanol oxidation is still required, but specific transcription as well as humoral factors also have important roles. Transcription factors involved include the sterol regulatory element binding protein 1 (SREBP-1) which is activated to induce genes that regulate lipid biosynthesis. Conversely, ethanol consumption causes a general down-regulation of lipid (fatty acid) oxidation, a reflection of inactivation of the peroxisome proliferator- activated receptor-alpha (PPAR-α) that regulates genes involved in fatty acid oxidation. A third transcription factor is the early growth response-1 (Egr-1), which is strongly induced prior to the onset of steatosis. The activities of all these factors are governed by that of the principal regulatory enzyme, AMP kinase. Important humoral factors, including adiponectin, and tumor necrosis factor-α (TNF-α), also regulate alcohol-induced steatosis. Their levels are affected by alcohol consumption and by each other. This review will summarize the actions of these proteins in ethanol-elicited fatty liver. Because steatosis is now regarded as a significant risk factor for advanced liver pathology, an understanding of the molecular mechanisms in its etiology is essential for development of effective therapies.展开更多
The composition of fatty acids in triacylglycerides （TAGs） and their position on the glycerol backbone de- termine the nutritional value of vegetable oil. In this study, gas chromatography and high-performance liqui...The composition of fatty acids in triacylglycerides （TAGs） and their position on the glycerol backbone de- termine the nutritional value of vegetable oil. In this study, gas chromatography and high-performance liquid chromatography-tandem mass spectrometry （HPLC-MS/MS） were used to analyze the compo- sition and distribution of fatty acids in TAGs of different rapeseed oils. Our results show the content of oleic acid in higb-oleic-acid rapeseed oil to be about 80%. In terms of the number of acyl carbon atoms （CN）, TAGs with CN52-54 were most abundant, with a maximum concentration at CN54 （80%）. The main type of TAG was oleic-oleic-oleic （OOO）, accounting for 71.75%, while oleic-oleic-linoleic （OOL） accounted for ？.56%, oleic-oleic-linolenic （OOLn） accounted for 4.81%, and stearic-oleic-oleic （SO0） accounted for 4.74%. Oleic acid in high-oleic-acid rapeseed oil was distributed in the following order of preference： sn-2 〉 sn-1/3. In high-erucic-acid rapeseed oil, however, oleic acid was enriched at the sn-1/3. These data show that the content of oleic acid can be as high as about 80% in high-oleic-acid material. This finding suggests that high-oleic-acid rapeseed oil has high nutritional value.展开更多
We compared four esterifiable enzymes. The lipase Novozym 435 possessed the highest activity for the conjugated linoleic acid esterification during the synthesis of triglycerides. The triglycerides were synthesized by...We compared four esterifiable enzymes. The lipase Novozym 435 possessed the highest activity for the conjugated linoleic acid esterification during the synthesis of triglycerides. The triglycerides were synthesized by esterification of glycerol and conjugated linoleic acid （CLA） in a no-solvent system using lipase catalysis. We investigated the effects of temperature, enzyme concentration, water content, and time on esterification. Enzyme and water concentrations of up to 1% of the total reaction volume and a system temperature of 60℃ proved optimal for esterification. Similarly, when the esterification was carried out for 24 h, the reaction ratio improved to 94.11%. The esterification rate of the rotating screen basket remained high （87.28%） when the enzyme was re-used for the 5th time. We evaluated the substrate selectivity of lipase （NOVO 435） and determined that this lipase prefers the 10,12-octadacadienoic acid to the 9,11-octadecadienoic acid.展开更多
基金Supported by New Research Grant from the University of Nebraska Medical Center, the NIAAA, and Medical Research Funds from the Department of Veterans Affairs, United States
文摘Alcohol-induced fatty liver (steatosis) was believed to result from excessive generation of reducing equivalents from ethanol metabolism, thereby enhancing fat accumulation. Recent findings have revealed a more complex picture in which ethanol oxidation is still required, but specific transcription as well as humoral factors also have important roles. Transcription factors involved include the sterol regulatory element binding protein 1 (SREBP-1) which is activated to induce genes that regulate lipid biosynthesis. Conversely, ethanol consumption causes a general down-regulation of lipid (fatty acid) oxidation, a reflection of inactivation of the peroxisome proliferator- activated receptor-alpha (PPAR-α) that regulates genes involved in fatty acid oxidation. A third transcription factor is the early growth response-1 (Egr-1), which is strongly induced prior to the onset of steatosis. The activities of all these factors are governed by that of the principal regulatory enzyme, AMP kinase. Important humoral factors, including adiponectin, and tumor necrosis factor-α (TNF-α), also regulate alcohol-induced steatosis. Their levels are affected by alcohol consumption and by each other. This review will summarize the actions of these proteins in ethanol-elicited fatty liver. Because steatosis is now regarded as a significant risk factor for advanced liver pathology, an understanding of the molecular mechanisms in its etiology is essential for development of effective therapies.
文摘The composition of fatty acids in triacylglycerides （TAGs） and their position on the glycerol backbone de- termine the nutritional value of vegetable oil. In this study, gas chromatography and high-performance liquid chromatography-tandem mass spectrometry （HPLC-MS/MS） were used to analyze the compo- sition and distribution of fatty acids in TAGs of different rapeseed oils. Our results show the content of oleic acid in higb-oleic-acid rapeseed oil to be about 80%. In terms of the number of acyl carbon atoms （CN）, TAGs with CN52-54 were most abundant, with a maximum concentration at CN54 （80%）. The main type of TAG was oleic-oleic-oleic （OOO）, accounting for 71.75%, while oleic-oleic-linoleic （OOL） accounted for ？.56%, oleic-oleic-linolenic （OOLn） accounted for 4.81%, and stearic-oleic-oleic （SO0） accounted for 4.74%. Oleic acid in high-oleic-acid rapeseed oil was distributed in the following order of preference： sn-2 〉 sn-1/3. In high-erucic-acid rapeseed oil, however, oleic acid was enriched at the sn-1/3. These data show that the content of oleic acid can be as high as about 80% in high-oleic-acid material. This finding suggests that high-oleic-acid rapeseed oil has high nutritional value.
基金Supported by the High Technology Research and Development Program of China (No 2007AA091905)the Technical Program of Municipal Technology Bureau Qingdao (No 04-2-JS-117)
文摘We compared four esterifiable enzymes. The lipase Novozym 435 possessed the highest activity for the conjugated linoleic acid esterification during the synthesis of triglycerides. The triglycerides were synthesized by esterification of glycerol and conjugated linoleic acid （CLA） in a no-solvent system using lipase catalysis. We investigated the effects of temperature, enzyme concentration, water content, and time on esterification. Enzyme and water concentrations of up to 1% of the total reaction volume and a system temperature of 60℃ proved optimal for esterification. Similarly, when the esterification was carried out for 24 h, the reaction ratio improved to 94.11%. The esterification rate of the rotating screen basket remained high （87.28%） when the enzyme was re-used for the 5th time. We evaluated the substrate selectivity of lipase （NOVO 435） and determined that this lipase prefers the 10,12-octadacadienoic acid to the 9,11-octadecadienoic acid.
