Wu G H, Jarstrand C, Nordenström J
Department of Clinical and Oral Bacteriology, Huddinge University Hospital, Karolinska Institute, Sweden.
Nutrition. 1999 May;15(5):359-64. doi: 10.1016/s0899-9007(99)00052-0.
Unsaturated fatty acids, a major component of fat emulsions used in parenteral nutrition, are prone to peroxidation which is an important feature of oxygen-associated tissue damage. We used the nitroblue tetrazolium (NBT) reduction test to measure the production of superoxide radicals by stimulated polymorphonuclear neutrophils (PMN) in the presence of different fat emulsions: Intralipid (containing 100% long-chain triacylglycerols, LCT), Vasolipid (a physical mixture of 50% LCT and 50% medium-chain triacylglycerols, MCT) and Structolipid (structured triacylglycerols containing 63% LCT and 37% MCT). We measured the amount of malonaldehyde (MDA) and 4-hydroxyalkenal to determine the lipid peroxidation of the three fat emulsions in the presence of stimulated neutrophils. Further, we investigated the role of vitamin E (alpha-tocopherol) in preventing lipid peroxidation in vitro. The results showed that the values of NBT reduction of PMN were significantly decreased in each of the three fat emulsions and that increasing concentrations of fat emulsions were associated with decreased values of NBT reductions, in a dose-dependent way (P<0.001). There were, however, no statistically significant differences between the values of the three different types of fat emulsions (P>0.05). Lipid peroxidation increased significantly in the presence of all three types of fat emulsions, and was more pronounced for Intralipid than for Vasolipid and Structolipid after 1 and 2 h of incubation with resting as well as with stimulated phagocytes. The increased lipid peroxidation of the fat emulsions was markedly reduced by vitamin E, and the inhibition was concentration dependent. In conclusion, lipid peroxidation in vitro is more pronounced when PMNs are incubated with fat emulsions. This increase in lipid peroxidation can be reduced by adding vitamin E to the fat emulsions.
不饱和脂肪酸是肠外营养中使用的脂肪乳剂的主要成分，容易发生过氧化反应，而过氧化反应是与氧相关的组织损伤的一个重要特征。我们使用硝基蓝四氮唑（NBT）还原试验，来测定在不同脂肪乳剂存在的情况下，受刺激的多形核中性粒细胞（PMN）产生超氧阴离子自由基的情况：英脱利匹特（含有100%长链三酰甘油，LCT）、力能（50% LCT和50%中链三酰甘油，MCT的物理混合物）和结构脂肪乳（含有63% LCT和37% MCT的结构化三酰甘油）。我们测定了丙二醛（MDA）和4-羟基烯醛的量，以确定在受刺激的中性粒细胞存在的情况下，这三种脂肪乳剂的脂质过氧化情况。此外，我们研究了维生素E（α-生育酚）在体外预防脂质过氧化中的作用。结果显示，在三种脂肪乳剂中，PMN的NBT还原值均显著降低，且脂肪乳剂浓度增加与NBT还原值降低相关，呈剂量依赖性（P<0.001）。然而，三种不同类型脂肪乳剂的值之间无统计学显著差异（P>0.05）。在所有三种类型的脂肪乳剂存在的情况下，脂质过氧化均显著增加，并且在与静息及受刺激的吞噬细胞孵育1小时和2小时后，英脱利匹特的脂质过氧化比力能和结构脂肪乳更明显。维生素E显著降低了脂肪乳剂增加的脂质过氧化，且这种抑制作用呈浓度依赖性。总之，当PMN与脂肪乳剂孵育时，体外脂质过氧化更明显。向脂肪乳剂中添加维生素E可减少这种脂质过氧化的增加。
