新生儿肝功能障碍时不同脂肪乳剂对血脂和肝功能影响的比较研究

目的 :比较中 /长链和长链脂肪乳剂对肝功能障碍新生儿血脂和肝功能的影响。　方法 :将 40例血清胆红素水平≥ 5 1.3μmol/L(3mg % )的新生儿随机分成两组 ,分别应用中 /长链脂肪乳剂 (MCT/LCT组 ,2 0 %Lipo fundin)和长链脂肪乳剂 (LCT组 ,2 0 %Intralipid) ,剂量均为 2 g/ (kg·d) ,持续 1周。在实验前、后分别抽血测定血脂和肝功能。　结果 :两组总胆固醇无显著变化 ,甘油三酯在LCT组升高 ,在MCT/LCT组下降 ,与实验前相比均无显著差异 ,组间比较MCT/LCT非常显著地低于LCT组。胆红素在两组均显著下降 ,但MCT/LCT组下降比LCT组更加显著。γ GT和ALP在LCT组无明显改变 ,但在MCT/LCT组却有显著降低 ,并显著低于LCT组。　结论 :在危重新生儿合并有肝功能障碍时 ,应用中 /长链脂肪乳剂显著优于长链脂肪乳剂。     

静脉输注长链及中/长链脂肪乳剂对脂蛋白代谢的影响

目的比较静脉输注长链(LCT)及中长链(MCT/LCT)脂肪乳剂时血浆脂蛋白代谢.方法选择12例健康志愿者进行前瞻性随机交叉对照研究, 连续输注MCT/LCT或LCT6小时(0.20g TG.Kg-1@h-1),测定研究前及输注中4h、6h、8h、12h及24h时血清TG、FFA,PL、FC、CE浓度以及血浆各脂蛋白成份.结果脂肪乳剂输注过程中,MCT/LCT组血清甘油三酯(TG)浓度明显低于LCT组,而血浆FFA浓度约为LCT组的3倍(p<0.001), MCT/LCT 的半衰期明显短于[LCT (68(12)分钟vs.(116(18)分钟,p<0.05].LCT组血浆游离胆固醇浓度明显高于MCT/LCT 组(p<0.05),而血浆胆固醇酯(CE)浓度在研究过程中两组均无明显变化.结论MCT/LCT的水解、代谢清除率要明显高于LCT,MCT/LCT输注时TG与LDL之间转换率较高,脂肪颗粒较少获取CE,其残余颗粒的清除也高于LCT.     

结构脂肪乳剂与物理混合的中/长链脂肪乳剂脂肪酸代谢比较研究

目的:比较结构脂肪乳剂(STG)与物理混合的中/长链脂肪乳剂(MCT/LCT)在人体内的脂肪酸代谢情况.方法:40例健康志愿者随机分为STG组和MCT/LCT组,每组20例.分别于早晨6h内匀速输注20%力文脂肪乳剂和20%力保肪宁脂肪乳剂1.0 g/(kg·次).并于给药前和给药后2、4、6和24 h留取血标本测定血...     

含维生素E的中/长链脂肪乳注射液临床应用进展

脂肪乳剂是全胃肠外营养(TPN)中的重要组成部分.随着TPN在临床营养治疗中的广泛应用,脂肪乳剂也逐渐由长链脂肪乳(LCT)发展至中/长链脂肪乳(MCT/LCT).MCT具有水解、氧化快而完全,不依赖肉毒碱转运,对免疫系统影响少,且不易在肝内和外周组织中浸润等优点.但其中仍含有一定量的多不饱和脂肪酸,易受体内自由基的攻击而产生脂质过氧化,进而损害脂质、DNA和蛋白质,造成组织和器官的损伤.因此,许多学者主张在MCT/LCT剂中添加一定量的维生素E,以防止脂肪乳剂脂质过氧化的发生,从而保证临床安全、合理地使用脂肪乳剂进行营养治疗的同时,有效地避免发生不良反应.以下主要对含维生素E的MCT/LCT注射液在临床的应用作一综述.     

长链脂肪乳剂及中/长链脂肪乳剂水解速率的比较研究

目的：比较长链脂肪乳剂、物理混合的中／长链脂肪乳剂及结构脂肪乳剂的水解速率。方法：应用1、^14C甘油棕榈酸标记的长链三酰甘油（LCT）和2，3－^3H甘油辛酸标记的中链三酰甘油（MCT），分别标记Intralipid,Lipofundin及Structolipid，在体外添加缓冲液、脂蛋白酯酶和肝酯酶后，置37℃温箱中水浴、卵育。采用气相色谱仪测定核素核记的各种脂肪酸及三酰甘油浓度，游离脂肪酸浓度用放射性核素扫描计数测定，通过计算培养液中^14C标记的长链脂肪酸及^3H标记的中链脂肪酸分别在^14C标记LCT及^3H标记MCT中的比例。来计算三种脂肪乳剂的水解率。结果：物理混合的中／长链脂肪乳剂及结构脂肪乳剂的水解程度明显高于长链脂肪乳剂，差异有统计学意义。物理混合的中／长链脂肪乳剂水解程度高于结构脂肪乳剂，但在水解程度及水解速度上却无统计学差异。结论：物理混合的中／长链脂肪乳剂及结构脂肪乳剂的水解率明显高于长链脂肪乳剂。     

肠外营养中脂肪乳剂对红细胞膜磷脂脂肪酸组成的影响

利用大鼠胃肠外营养(PN)模型观察长链脂肪乳剂(LCT),中链/长链脂肪乳剂(MCT/LCT),以及不含脂肪乳剂对红细胞(RBC)膜磷脂肪酸组成的影响。PN总热量为300kcal.kg~(-1).d~(-1),非蛋白热卡:氮为182:1,LCT组,MCT/LCT组分别由10％的Intralipid和10％的Lypofundin提供30％的非蛋白热卡。7天后,分析RBC膜磷脂酰二极管胆硷(PC)脂肪酸组成。结果发现,不含脂肪乳剂组18:1n-9明显高于对照组;LCT组18:2n-6升高,而20:4n-6却下降;MCT/LCT组与对照组相比,脂肪酸组成变化不明显。结论:无脂肪乳剂TPN导致必需脂肪酸缺乏;LCT组由于18:2n-6的过量供给,抑制Δ6去饱和酶的活性,MCT/LCT组由于50％LCT被MCT替代,减低了对此酶活性抑制。     

中链甘油三酯干预对2型糖尿病血脂和血浆游离脂肪酸的影响

目的探讨中链甘油三酯(MCT)干预对2型糖尿病(T2DM)患者体重、血脂和血浆游离脂肪酸的影响。方法以长链甘油三酯(LCT)为对照,将所有T2DM患者分为MCT组、MCT/LCT组和LCT组,在控制总能量和脂肪摄入量的基础上,3组分别连续食用100%MCT油、50%MCT油 50%LCT油和100%LCT油12周。在0、6和12周时检测血浆总胆固醇(TC)、甘油三酯(TG)、低密度脂蛋白胆固醇(LDL-C)、高密度脂蛋白胆固醇(HDL-C)、载脂蛋白A1(ApoA1)和载脂蛋白B(ApoB)浓度以及血浆游离脂肪酸浓度。计算体质指数(BMI)、LDL/HDL、ApoA1/ApoB、总游离脂肪酸(TFFA)、长链饱和脂肪酸(LCSFA)和不饱和脂肪酸(USFA)浓度。结果在6和12周时,MCT和MCT/LCT组的体重和BMI均较LCT组低(P<0.05)。在12周时MCT/LCT组的TC水平较LCT组低(P<0.05)。与实验前相比,MCT/LCT组6和12周时的LDL-C水平均显著下降(P<0.05);与6周时相比,MCT组12周时的LDL-C水平显著下降(P<0.05)。12周时LCT组的HDL-C水平较MCT组高(P<0.05)。与MCT组相比,LCT组的LCSFA水平在6周时显著升高(P<0.05)。3组的TFFA和USFA水平差异无显著性。结论在控制总能量和脂肪摄入量的基础上,用MCT取代100%或50%的膳食油脂,患者的BMI和血脂谱得到改善,而血浆游离脂肪酸无明显变化。     

中、长链脂肪乳剂对肝硬化门脉高压术后脂代谢及自然病程的影响

研究比较 PHT病人术后支持中 ,应用含长链甘油三酯与中 /长链混合甘油三酯的脂肪乳剂体内代谢对机体的影响。选择 1996年 9月～ 1997年 5月普外科收住治疗的肝硬化门脉高压病人共 15例 ,前瞻性随机分为长链脂肪乳组(L CT组 ) (8例 )及中链组 (MCT组 ) (7例 ) ,术后 1～ 7天均予肠外营养支持。结果 :MCT组术前及术后 7天甘油三酯的K2 和 t1 /2 明显优于 L CT组 ,两组氮平衡与血浆蛋白变化无明显差异 ,MCT组的 Ig G、Ig E、CD3、CD4及比值的 NKC在PN第 7天时有所升高 ,与 L CT组相比有明显差异。研究结果表明 MCT乳剂在创伤、…     

结构脂肪乳剂改善腹部手术后病人的氮平衡和蛋白质代谢

目的:观察结构脂肪乳剂(STG)和物理混合的中、长链脂肪乳剂(MCT/LCT)对腹部中等及中等以上手术创伤病人氮平衡和蛋白质代谢的影响.方法:腹部中等及中等以上手术病人随机分为两组,术后第2天开始分别使用STG和MCT/LCT构成的等氮、等热量肠外营养支持5天,术后第1天至第6天留取标本检测氮平衡,术前、术后第1天及术后第6天抽取静脉血检测血清前清蛋白水平,术前及术后第6天称取体质量,记录住院日.结果:围手术期使用STG和MCT/LCT的静脉营养,均可以纠正创伤病人的负氮平衡,促进血清前清蛋白的合成.其中STG可以更明显地改善手术创伤病人的负氮平衡,增加血清前清蛋白水平,但在维持病人体质量和缩短住院日上,STG与MCT/LCT脂肪乳相比差异并不明显.结论:在改善手术创伤病人的蛋白质代谢上,STG比物理混合的MCT/LCT脂肪乳剂更加优越.     

不同碳链脂肪乳剂对肝脏外科病人术后的影响

目的观察两种不同碳链脂肪乳剂对肝脏外科病人术后自然病程的影响。方法选择肝脏外科病人25例，随机分为两组；长链脂肪乳剂组（n＝12，简称LCT组），中／长链脂肪乳剂组（n=13，简称MCT组）。LCT组脂肪乳剂为20％Inralipid，MCT组为20％Lipofundin，连续观察1周。在术前，术后1、4、7天测定肝功能、血脂、血及尿液中肉毒碱（CNT）以及激素的变化。结果两组对肝脏酶学无明显影响。胆红素在术后1天明显升高，但MCT组随后显著下降，LCT组下降速度慢于MCT组，P＜0．05。PN期间血脂代谢无异常。CNT术后明显升高，尿排出减少，术后7天LCT组血CNT高于MCT组，尿CNT低于MCT组，P＜0．05。血皮质醇、胰岛素（I）、G以及G／I术后第1天均明显升高，随后逐渐下降，而LCT组术后7天，胰高糖素（G）以及G／I维持在较高水平。血糖术后明显升高，术后4、7天，LCT组持续在较高水平，MCT组已属正常。结论MCT／LCT乳剂可能是肝脏外科病人更为理想的脂肪能源。     

Comparison of metabolic clearance rates of MCT/LCT and LCT emulsions in diabetics

In seven moderately overweight noninsulin-dependent diabetics with slightly elevated triglyceride levels, disappearance rates of infused medium chain triglyceride/long chain triglyceride (MCT/LCT) and long chain triglyceride (LCT) emulsions were compared. Five metabolically healthy volunteers served as controls. During a 3-hr lipid infusion, serum triglycerides reached a steady state with both emulsions in the healthy controls, whereas, in diabetic patients, steady state triglyceride levels were seen only with MCT/LCT. After the end of the lipid infusion, the longest half-life value in the decline of triglyceride levels was found with LCT in diabetics, whereas significantly shorter and quite similar half-life values were found with LCT in healthy controls and with MCT/LCT in diabetics. As expected, the shortest half-life for serum triglycerides was found in healthy controls after MCT/LCT-infusion. Virtually the same differences in serum concentrations and in half-life times were seen with free fatty acids. According to these data, if needed, parenteral nutrition with lipids in states of disturbed glucose and lipid metabolism may preferentially be done with MCT/LCT emulsions.     

Total parental nutrition using conventional and medium chain triglycerides: effect on liver function tests, complement, and nitrogen balance

Conventional long chain triglyceride (LCT) was compared with a new emulsion containing 50% medium chain triglyceride (5% MCT/5% LCT) in a randomized cross-over trial of 10 days duration. Plasma concentrations of albumin, prealbumin, the complement components C3 and C4, and prothrombin times measured daily at 8 am, before lipid infusion, showed no progressive change during the 10 days of the trial, nor in each separate 5-day period when LCT or MCT/LCT was infused. Aspartate transaminase and alkaline phosphatase activities were similar over the two periods. There was a significant increase (compared with preinfusion levels) in C3 and C4 levels after 5 hr of either lipid infusion. Nitrogen balance was improved, and plasma bilirubin levels were lower on the regimen containing MCT/LCT.     

Parenteral nutrition using MCT/LCT or LCT: Effect on the fatty acid composition of plasma triglycerides and platelet phospholipids

Plasma triglyceride fatty acids and platelet phospholipid fatty acids were compared in 20 malnourished patients before and after 8-10 days of total parenteral nutrition which included either a conventional lipid emulsion (LCT) or a new emulsion containing medium chain triglyercides (MCT/LCT). The use of both lipid emulsions altered the fatty acid profiles. The percentage of linoleic acid in the plasma triglycerides increased with both lipid emulsions, but more markedly with LCT. The median percentage after LCT was 25.9 (range 16.9-31.5) which was significantly higher (p < 0.01) than after MCT/LCT - 14.8 (range 6.1-20.2), or in healthy volunteers. After 8-10 days on MCT/LCT the fatty acid profile retained some features of the malnourished state, despite correction of the linoleic acid content. The percentage of linolenic and arachidonic acid in the platelet phospholipids tended to be lower than after LCT use, and the percentage of linoleic acid was significantly less (p < 0.01), the median (range) being 8.2 (4.5-23.8) after MCT/LCT and 11.7 (4.8-16.0) on LCT. Short term use of MCT/LCT emulsion may correct the fatty acid changes of malnutrition rather more slowly and results in a different fatty acid profile to that seen after LCT use. Whether this has any clinical effects is unclear.     

MCT/LCT emulsion ameliorate liver fat deposition in insulin-treated diabetic rats receiving total parenteral nutrition

This study was designed to investigate the effects of high energy infusion and insulin treatment on plasma and liver lipids in diabetic rats receiving total parenteral nutrition (TPN). Diabetes was induced in rats by streptozotocin. The diabetic rats were assigned to two TPN groups to receive either long chain triglyceride (LCT) or medium chain triglyceride (MCT)/LCT (1:1) as a fat source. The TPN solutions were isonitrogenous, isocaloric and identical in nutrient composition except for the fat emulsion. All rats received the TPN solution at an energy level of 35|kcal/100|g of body weight. The LCT and MCT/LCT groups were further divided into two subgroups, depending on whether they were treated with insulin. The results demonstrated that, between the MCT/LCT and LCT groups, no differences were observed in body weight and nitrogen retention, as well as the concentrations of plasma glucose, nonesterified fatty acids, beta-hydroxybutyrate, and total cholesterol. Diabetic TPN rats without insulin treatment had weight loss and negative nitrogen balance during the experiment. Diabetic TPN rats treated with insulin, however, demonstrated less weight loss and positive nitrogen retention. Insulin treated groups had significantly higher liver fat content than did those without insulin treatment. Furthermore, liver fat content was significantly higher in the LCT group than in the MCT/LCT group among insulin treated TPN rats. These results suggest that compared with the LCT emulsion, infusion of the MCT/LCT emulsion ameliorated liver fat deposition in insulin-treated diabetic rats receiving TPN.     

Lipoprotein metabolism during and after a 6-h infusion ofMCT/LCT vs LCT emulsion in man

We studied, in man, the intravascular metabolism of two lipid emulsions differing in their triglyceride (TG) fatty acid pattern. One emulsion was composed exclusively of soy bean long-chain triglycerides (LCT), the other of a mixture containing a (1:1, wt:wt) ratio of medium-chain triglycerides (MCT) and LCT (MCT/LCT). Both emulsions contained 10% TG and 1.2% of the same egg yolk phospholipid emulsifier. Six healthy volunteers received both emulsions, in random order, at a rate of 0.2 g TG/kg.h for 6 h. An interval of 2 weeks separated the tests. Although the MCT/LCT emulsion provided 39% more TG molecules than the pure LCT emulsion, plasma TG increased to similar levels, indicating a faster elimination of MCT/LCT. The rise of plasma non esterified fatty acids was greater with MCT/LCT (P < 0.001). LDL-TG enrichment was higher with MCT/LCT (P < 0.025) while net transfer of TG to HDL was similar with both emulsions. Cholesteryl ester (CE) enrichment in the 'VLDL' fraction (largely composed of emulsion particles) was markedly less during MCT/LCT than LCT infusions (P < 0.01). CE enrichment of the 'VLDL' fraction persisted up to 6 h after cessation of both lipid infusions. In conclusion, TG from MCT/LCT emulsion appear to be eliminated faster than LCT during an in vivo infusion in man. In accordance with our previous in vitro data, MCT/LCT infusion was associated with a higher transfer of TG to LDL and in a reverse manner, with a lesser acquisition of CE by emulsion particles as compared to LCT infusion.     

A new intravenous emulsion containing medium-chain triglyceride: studies of its metabolic effects in the perioperative period compared with a conventional long-chain triglyceride emulsion

The effects of carbohydrate, lipid, and nitrogen metabolism of recently available lipid emulsions containing either 50% medium-chain triglyceride (MCT) and 50% long-chain triglyceride (LCT) or 100% LCT were compared in elective surgical patients. Postoperative urinary urea excretion was similar during isocaloric MCT/LCT and LCT infusions (1.9 mg/kg/min) and was decreased compared with a standard infusion of 5% glucose (1 mg/kg/min). Plasma glucose and insulin concentrations were similar during both lipid and low dose glucose infusions. However, plasma triglyceride and nonesterified fatty acid concentrations were decreased during the MCT/LCT infusion compared with the LCT infusion, suggesting that the MCT/LCT emulsion was cleared from the circulation faster than pure LCT. Ketone body concentrations were similar during all three infusions. MCT/LCT emulsion can be safely infused perioperatively and has similar nitrogen conserving properties to LCT in these circumstances.     

Medium chain triglycerides in septic patients on total parenteral nutrition

The object of this study was to compare the metabolic effects of a 10% long chain triglyceride (LCT) emulsion with those produced by a 10% emulsion of medium and long chain triglycerides, MCT/LCT. During 7 days, 20 septic patients received total parenteral nutrition. Daily between 9:00 and 21:00 hours, 0.14 ± 0.01 triglycerides/kg body weight/h was infused. Nine received an LCT emulsion, 11 an MCT/LCT emulsion. Venous blood samples were taken on each of the 7 days at 09:00 and 17:00 hours. No signs of complications attributable to the lipid infusion were observed. The plasma concentrations of phospholipids, triglycerides, free glycerol, non-esterified fatty acids, and sometimes cholesterol, rose during the lipid infusion. Blood ketone body levels did not increase. With both emulsions a day by day acumulation of phospholipids (at09:00 and 17:00 hours) in the plasma was observed. Cholesterol also accumulated but only with the LCT emulsion. The nitrogen balance and urinary excretion of creatinine and of 3-methylhistidine/creatinine ratio was lower with the MCT/LCT emulsion, which suggests less muscular catabolism in patients receiving that emulsion.     

Effect of emulsions of medium and long chain triglyceride on human adipose tissue prostaglandin production in vitro

Preliminary in vitro studies have been performed to assess the effect of experimental lipid emulsions of varying fatty acid composition on human adipose tissue metabolism. Subcutaneous human adipose tissue was obtained during elective surgery and placed in tissue culture. Physical mixtures of long chain triglyceride (LCT) and/or medium chain triglyceride (MCT) were added to the tissue culture medium so that the final concentration was 400 mg/dl. After a 3-day incubation period the tissue was harvested, placed in buffer and used to determine in vitro production of the prostaglandins prostacyclin I2 (measured as its stable endproduct 6-keto PGF1 alpha), thromboxane A2 (measured as TXB2), and prostaglandin E2. Measurements of the fatty acid profile found in the neutral- and phospholipid fraction of the adipose tissue and fat cell size were also made. The results demonstrate that samples incubated in 100% MCT had the most significant increase in prostaglandin production whereas those incubated in 100% LCT had the most significant decrease in activity of the three prostaglandins assayed, when compared to controls. The addition of LCT to MCT caused a dose-related decrease in adipose tissue prostaglandin production. There were no significant changes in the profile of fatty acids found in the neutral- or phospholipid fraction of adipose tissue. The results indicate that the relative level of MCT/LCT incubated with human adipose tissue has a significant effect on prostaglandin production.     

Effects of 2 lipid emulsions (LCT versus MCT/LCT) on the fatty acid composition of plasma phospholipid: a double-blind randomized trial

BACKGROUND: Fatty acids from the diet or from IV fat emulsions are incorporated into the plasma and cell membrane phospholipids and act as substrates in the synthesis of eicosanoids. This study reports the effect of 2 parenteral lipid emulsions in plasma phospholipids fatty acids. METHODS: A total of 83 patients aged 18 to 75 years were randomized to receive long-chain triglycerides (LCT) or 50/50 mix of long- and medium-chain triglyceride emulsion (LCT/MCT). Blood samples were collected at baseline and at weekly intervals for 28 days. Plasma phospholipid fatty acids were measured by gas chromatography. RESULTS: Patients receiving LCT versus MCT/LCT emulsion have an increase in 18:2n6 and a decrease in 20:4n6 and 22:4n6 after 7, 14, and 21 days of treatment with parenteral nutrition. Phospholipid fatty acids at 15 days of treatment with parenteral nutrition with LCT versus MCT/LCT for 18:2n6 were 17.30% versus 22,90% (p < .05), for 20:4n6 10.44% versus 8.38% (p < .05), and for 22:4n6 0.51% versus 0.40% (p < .05). The 20:4n6 percentage inversely correlated with the percentage of 18:2n6 on days 7, 14, and 21: regression coefficients: -7.40 (p < .001), -7.39 (p < .001), and 5.70 (p < .001), respectively. CONCLUSIONS: Parenteral lipid emulsions modify fatty acid profiles in plasma phospholipids. MCT/LCT emulsions produce in phospholipids a fatty-acid profile that is closer to normality than that achieved with LCT emulsions. These changes in phospholipid fatty acids are suggestive of an inhibition of A-5-desaturase in patients who received LCT emulsions.