响应面优化酶促油酸甘油酯化制备甘三酯工艺的研究

采用响应面法对脂肪酶Novozym 435在无溶剂体系中催化甘油和油酸酯化反应合成甘三酯的反应条件进行了研究。结果表明:底物摩尔比、反应时间、反应温度和加酶量都对甘三酯的含量有影响(p<0.05),其中底物摩尔比影响最为显著(p=0.0104)。经过响应面优化得到的最佳反应条件为:底物摩尔比(油酸∶甘油)2.92∶1,反应时间12 h,反应温度98℃,加酶量(以占油酸和甘油总质量的百分比计)2.96%。在最优条件下,甘三酯含量可达到90.88%±1.56%,酯化度达到93.09%±1.42%。

甘三酯氢过氧化物对“半胱氨酸-葡萄糖”体系肉香味形成的影响

为探讨氧化脂肪在肉香味形成中产生作用的机理,采用固相微萃取/气-质联机分析挥发性成分,研究"半胱氨酸-葡萄糖"模型反应中添加3种脂肪初级氧化产物——三亚油酸甘三酯单氢过氧化物、二亚油酸油酸甘三酯单氢过氧化物、二亚油酸油酸甘三酯双氢过氧化物对肉香味物质形成的影响。检测到的挥发性化合物主要包括醛、酮、醇等脂质降解成分。硫醇、噻吩、噻唑、含氧杂环、含氮杂环等来源于美拉德反应或脂质氧化与美拉德反应相互作用成分。比较各反应体系的挥发性成分,3种甘三酯单氢过氧化物均对美拉德反应有抑制作用,尤其表现为来源于美拉德反应的硫醇类化合物含量显著减少,而新出现一些来源于美拉德反应与脂质降解相互作用的烃基取代的噻吩、噻唑、吡啶类化合物。比较添加3种氢过氧化物的反应体系,无论是美拉德反应活性还是脂质降解反应活性,均是三亚油酸甘三酯的单氢过氧化物高于二亚油酸油酸甘三酯的单氢过氧化物,二亚油酸油酸甘三酯的双氢过氧化物高于其单氢过氧化物。

Alcohol-induced steatosis in liver cells

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.

Relationship between hyperuricemia and metabolic syndrome

Objective: To investigate the relationship between metabolic syndrome and hyperuricemia. Methods: A total of 2 374 subjects who received health examination in our hospital from Jan. 2004 to Dec. 2006 were enrolled in our study. Hyperuricemia is defined as ≥7 mg/dl (in men) or ≥6.0 mg/dl (in women). Metabolic syndrome was defined using AHA/NHLBI (American Heart Association/National Heart, Lung, and Blood Institute) criteria. Results: (1) The overall prevalence of hyperuricemia was 13.10%. The condition was more common in men than in women (19.07% vs 3.42%). (2) Among men, uric acid concentration is statistically significantly positively correlated with waist circumference, blood pressure, and triglyceride. Uric acid is negatively correlated with serum high-density lipoprotein-cholesterol (HDL-C). Uric acid concentration is most strongly correlated with serum triglyceride (r=0.379) and waist circumference (r=0.297). Among women, statistically significant positive correlations were noted for the serum uric acid concentrations with waist circumference, triglyceride and fasting plasma glucose. Serum triglyceride (r=0.329) and waist circumference (r=0.234) are most strongly correlated with uric acid concentrations. (3) Men with hyperuricemia had a 1.634-fold increased risk of metabolic syndrome as compared with those without hyperuricemia odds ratio (OR)=1.634, P=0.000. Women with hyperuricemia had a 1.626-fold increased risk of metabolic syndrome (OR=1.626, P=0.000) as compared with those without hyperuricemia. Conclusion: Hyperuricemia is prevalent among Chinese population. Additionally, serum uric acid is positively associated with metabolic syndrome.

Chylous ascites secondary to hyperlipidemic pancreatitis with normal serum amylase and lipase

A 54-year old man with a family history of hyperlipidemia was admitted with a 12 h history of severe generalized abdominal pain associated with nausea, vomiting and abdominal distension. Examination of the abdomen revealed tenderness in the periumblical area with shifting dullness. Serum pancreatic amylase was 29 IU/L and lipase 44 IU/L, triglyceride 36.28 mmol/L. Ultrasound showed ascites. CT of the abdomen with contrast showed inflammatory changes surrounding the pancreas consistent with acute pancreatitis. Ultrasound (US) guided abdomen paracentesis yielded a milky fluid with high triglyceride content consistent with chylous ascites. The patient was kept fasting and intravenous fluid hydration was provided. Meperidine was administered for pain relief. On the following days the patient’s condition improved and he was gradually restarted on a low-fat diet, and fat lowering agent (gemfibrozil) was begun, 600 mg twice a day. On d 14, abdomen US was repeated and showed fluid free peritoneal cavity. The patient was discharged after 18 d of hospitalization with 600 mg gemfibrozil twice a day. At the time of discharge, the fasting triglyceride was 4.2 mmol/L. After four weeks the patient was seen in the clinic, he was well.

Hepatic lipid metabolism changes in short-and long-term prehepatic portal hypertensive rats

AIM: To verify the impairment of the hepatic lipid metabolism in prehepatic portal hypertension. METHODS: The concentrations of free fatty acids, diacylglycerol, triglycerides, and phospholipids were assayed by using D-[U-14C] glucose incorporation in the different lipid fractions and thin-layer chromatography and cholesterol was measured by spectrophotometry, in liver samples of Wistar rats with partial portal vein ligation at short- (1 mo) and long-term (1 year) (i.e. portal hypertensive rats) and the control rats. RESULTS: In the portal hypertensive rats, liver phospholipid synthesis significantly decreased (7.42 ± 0.50 vs 4.70 ± 0.44 nCi/g protein; P < 0.01) and was associated with an increased synthesis of free fatty acids (2.08 ± 0.14 vs 3.36 ± 0.33 nCi/g protein; P < 0.05), diacylglycerol (1.93 ± 0.2 vs 2.26 ± 0.28 nCi/g protein), triglycerides (2.40 ± 0.30 vs 4.49 ± 0.15 nCi/g protein) and cholesterol (24.28 ± 2.12 vs 57.66 ± 3.26 mg/g protein; P < 0.01). CONCLUSION: Prehepatic portal hypertension in rats impairs the liver lipid metabolism. This impairment consists in an increase in lipid deposits (triglycerides,diacylglycerol and cholesterol) in the liver, accompanied by a decrease in phospholipid synthesis.

Polymorphisms of microsomal triglyceride transfer protein in different hepatitis B virus-infected patients

AIM: To identify the two polymorphisms of microsomal triglyceride transfer protein (MTP) gene in the Chinese population and to explore their correlation with both hepatitis B virus (HBV) self-limited infection and persistent infection. METHODS: A total of 316 subjects with self-limited HBV infection and 316 patients with persistent HBV infection (195 subjects without familial history), matched with age and sex, from the Chinese Han population were enrolled in this study. Polymorphisms of MTP at the promoter region -493 and at H297Q were determined by the allele specific polymerase chain reaction (PCR). RESULTS: The ratio of males to females was 2.13:1 for each group and the average age in the self-limited and chronic infection groups was 38.36 and 38.28 years, respectively. None of the allelic distributions deviated significantly from that predicted by the Hardy-Weinberg equilibrium. There was a linkagedisequilibrium between H297Q and -493G/T (D’ = 0.77). As the χ2 test was used, the genotype distribution of MTP -493G/T demonstrated a significant difference between the self-limited infection group and the entire chronic group or the chronic patients with no family history (χ2 = 8.543, P = 0.015 and χ2 = 7.199, P = 0.019). The allele distribution at the MTP-493 position also demonstrated a significant difference between the study groups without family history (χ2 = 6.212, P = 0.013). The T allele emerged as a possible protective factor which may influence the outcomes of HBV infection (OR: 0.59; 95% CI: 0.389-0.897). CONCLUSION: The polymorphism of the MTP gene, T allele at -493, may be involved in determining the HBV infection outcomes, of which the mechanism needs to be further investigated.

Roles of the Lipid Metabolism in Hepatic Stellate Cells Activation

Abstract The lipids present in hepatic stellate cells （HSCs） lipid droplets include retinyl ester, triglyceride, cholesteryl ester, cholesterol, phospholipids and free fatty acids. Activation of HSCs is crucial to the development of fibrosis in liver disease. During activation, HSCs transform into myofibroblasts with concomitant loss of their lipid droplets and production of excessive extracellular matrix. Release of lipid droplets containing retinyl esters and triglyceride is a defining feature of activated HSCs. Accumulating evidence supports the proposal that recovering the accumulation of lipids would inhibit the activation of HSCs. In healthy liver, quiescent HSCs store 80% of total liver retinols and release them depending on the extracellular retinol status. However, in injured liver activated HSCs lose their retinols and produce a considerable amount of extracelhilar matrix, subsequently leading to liver fibrosis. Further findings prove that lipid metabolism of HSCs is closely associated with its activation, yet relationship between activated HSCs and the lipid metabolism has remained mysterious.

A Study on Triacylglycerol Composition and the Structure of High-Oleic Rapeseed Oil

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.

Optimization of conjugated linoleic acid triglycerides via enzymatic esterification in no-solvent system

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.

Impact of environmental and dietary factors on the course of inflammatory bowel disease

Besides their possible effects on the development of inflammatory bowel disease(IBD),some environmental factors can modulate the clinical course of both ulcerative colitis(UC) and Crohn's disease(CD).This review is mainly devoted to describing the current knowledge of the impact of some of these factors on the outcome of IBD,with special emphasis on smoking and diet.Although the impact of smoking on the susceptibility to develop CD and UC is firmly established,its influence on the clinical course of both diseases is still debatable.In CD,active smoking is a risk factor for postoperative recurrence.Beyond this clinical setting,smoking cessation seems to be advantageous in those CD patients who were smokers at disease diagnosis,while smoking resumption may be of benefit in ex-smokers with resistant UC.The role of dietary habits on the development of IBD is far from being well established.Also,food intolerances are very frequent,but usually inconsistent among IBD patients,and therefore no general dietary recommendations can be made in these patients.In general,IBD patients should eat a diet as varied as possible.Regarding the possible therapeutic role of some dietary components in IBD,lessons should be drawn from the investigation of the primary therapeutic effect of enteral nutrition in CD.Low-fat diets seem to be particularly useful.Also,some lipid sources,such as olive oil,medium-chain triglycerides,and perhaps omega-3 fatty acids,might have a therapeutic effect.Fermentable fiber may have a role in preventing relapses in inactive UC.

Effects of Dietary Carbohydrates Sources on Lipids Compositions in Abalone, Haliotis discus hannai Ino

A study was conducted to evaluate the effects of dietary carbohydrates on triglyceride, cholesterol and fatty acid concentrations in abalone, Haliotis discus hannai Ino. Six semi-purified diets with different carbohydrates （dextrin, heat-treated wheat starch, wheat starch, corn starch, tapioca starch and potato starch, respectively）, all containing a carbohydrate level of 33.5%, were fed to abalone （initial shell length： 29.98mm±0.09mm; initial weight. 3.42g±0.02g） for 24 weeks in a recirculation system. The results indicate that serum triglyceride concentrations were significantly （P〈0.05） higher in the abalone fed with dextrin, heat-treated wheat starch and wheat starch than those fed with corn starch, and serum cholesterol concentrations were significantly （P〈0.05） higher in the abalone fed with dextrin, heat-treated wheat starch than those fed with corn starch. Fatty acid C20：4n-6 in the foot mus- cles were significantly （P〈0.05） lower in the abalone fed with dextrin than those fed with wheat starch, corn starch, tapioca starch and potato starch. Fatty acid C20：4n-6 in hepatopancreas was significantly （P〈0.05） lower in abalone fed with heat-treated wheat starch than those fed with corn starch, tapioca starch and potato starch. Fatty acid C22：6n-3 in the foot muscles were significantly （P 〈 0.05） lower in the abalone fed with dextrin and beat-treated wheat starch than those fed with wheat starch and potato starch.

Role of cyclooxygenase-2 in lipid metabolism in hepatic stellate cells

Hepatic stellate cells(HSCs) are a kind of adipocytes. In HSCs lipids mainly exist in the form of lipid droplets. They are abundantly found in the cytoplasm and their main constituents are triglycerides. Lipid metabolism in HSCs is closely related to its biological activity, however the mechanism of lipid droplets disappearance after HSC activation is not clearly established yet. Recent research shows that, cyclooxygenase-2 plays an important regulatory role in the lipid metabolism of HSCs. This paper seeks to review the subject based on studies that have been conducted so far to understand the role of cyclooxygenase-2 in the metabolism of lipids in HSCs.

EFFECT OF ACUPUNCTURE TREATMENT ON CELLULAR HEMORHEOLOGY, CHOLESTEROL AND TRIGLYCERIDE OF SIMPLE OBESITY PATIENTS

Objective: To observe the effect of acupuncture on simple obesity and cellular hemorheology. Methods: Thirty-two cases of simple obesity patients were enrolled into this study. Acupoints of the Stomach Meridian and Spleen Meridian as Zhongwan (中脘 CV 12), Liangmen (梁门 ST 21), Tianshu (天枢 ST 25), Guayuan (关元 CV 4), etc. were punctured, once daily in the first 5 days, and once every other day afterwards, with 10 sessions being a therapeutic course. Before treatment and after 3 courses of treatment, the body weight, waistline, weight index, seam cholesterol (CH), triglyceride and aggregation index of red blood cell (RBC) were detected. Results: After acupuncture treatment, all the indexes of body weight, waistline, weight index, serum CH, triglyceride and aggregation index of RBC decreased significantly in comparison with those of pre-treatment(P< 0.05). Conclusion: Acupuncture can apparently improve cellular hemorheology, reduce body weight, serum cholesterol and TG levels in simple obesity patients.

COMPARISON OF ENERGY RESERVES AND UTILIZATION IN LIPOSCELIS BOSTRYCHOPHILA POPULATIONS SELECTED FOR TOLERANCE TO CONTROLLED ATMOSPHERE

One population of Liposcelis bostrychophila Badonnel (CA selected) was exposed to a controlled atmosphere(CA) (35% CO 2+1% O 2, balance N 2) for 30 generations. Another population (control) was reared under natural atmospheric conditions. Reserves of triacylglycerol, polysaccharides and free amino acids were evaluated in adults of the CA selected and the control populations in generations F 15 and F 30 The utilization rate of triacylglycerol and polysaccharides in the CA exposure were also determined in generation F 30. The results indicate that the reserves of triacylglycerol and polysaccharides increased significantly during selection for CA tolerance; the higher the tolerance level, the greater the reserves. A total of 15 free amino acids constituents were detected in both populations. The total amino acid content in the CA selected population was obviously higher than that in the control population. Exposure of this population to a controlled atmosphere was associated with a steady utilization of reserves. In contrast, the unselected population responded to the controlled atmosphere by accelerated utilization of triacylglycerol and polysachharides. Comparison of utilization rates during CA exposure showed that triacylglycerol is the main energy source, and polysaccharides contribute only a small extent to the metabolic energy supply.