静脉输注长链或中长链脂肪酸脂肪乳剂对急性坏死性胰腺炎大鼠脂质介质的影响

目的：探讨静脉输注长链或中长链脂肪酸脂肪乳剂对急性坏死性胰腺炎（ANP）大鼠血浆脂质介质及胰腺病理改变的影响。方法：雄性SD大鼠43只随机入组，A－C为非胰腺炎组：A组为正常组；B组正常大鼠输注脂肪乳剂；C组为手术对照组，输注葡萄糖液。D－F为ANP模型组：分别为全糖组，Intralipid组和Lipofundin组。测定A组血淀粉酶、前列腺素类，胰腺行病理学检查。测定B－F组术后4、48及72h血淀粉酶、前列腺素类，胰腺病理学检查并评分。结果：正常大鼠输注Intralipid不引起血前列腺素的变化。在胰腺炎各组，脂肪乳剂可提高4h6－keto-PGF1α、PGE2血浆浓度；Lipofundin组胰腺组织的出血和脂肪坏死明显减少。结论：脂肪乳剂不加重ANP大鼠胰腺组织病理损害；LCT／MCT脂肪乳剂更适合应用于ANP。     

Short-term effects of fat emulsion on serum lipids in postoperative patients

The effect of short-term infusion of intravenous fat on serum lipids was assessed in 23 patients who had elective cancer operations and were given 20% Intralipid for 5 days postoperatively as part of a standard total parenteral nutrition regimen. Serum lipids were measured prior to, during and after the 5-day infusion period. The percentage of cholesterol as high-density lipoproteins (HDL) fell from a mean preinfusion value of 34.7 +/- 2.8 to 27.9 +/- 2.5 (p less than 0.05), while the percentage of cholesterol as low-density lipoproteins (LDL) increased from 40.7 +/- 2.2 to 46.8 +/- 3.4 (p less than 0.05). Serum triglycerides fell significantly (p less than 0.01) from 106.2 +/- 13.7 mg/dl to 64.6 +/- 8.8 mg/dl at 3 days, being 85.3 +/- 3.7 mg/dl at 5 days. No significant change in percent cholesterol as very low-density lipoproteins (VLDL), or levels of serum total cholesterol or phospholipids occurred. Lipoprotein X was detectable in six patients after 5 days. To study triglyceride clearance 1.7 g/kg of fat emulsion was infused over 8 hr and serial blood samples obtained. Within 3 hr of stopping the fat infusion, triglyceride levels had fallen to preinfusion values.     

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.     

骨骼肌条件培养液对胸部恶性肿瘤抑制作用的实验研究

目的研究骨骼肌微环境因素对胸部恶性肿瘤细胞增殖的影响,评价其在骨骼肌转移瘤罕见性中的意义及其临床应用前景。方法原代培养新生W istar大鼠骨骼肌细胞,用MTT法分析、比较其条件性上清液(MMCM)对胸部恶性肿瘤细胞(A549,肺泡细胞癌细胞株;An ip-973,肺腺癌细胞株腹水型亚系;PLA-801C,肺巨细胞癌细胞株;NC I-H466,肺小细胞癌细胞株;Eca109,人食管鳞癌细胞株)及正常非肿瘤细胞(金黄地鼠肾细胞株BHK-21)的体外抑瘤作用。结果MMCM分别与A549、An ip-973、PLA-801C、NC I-H466、Eca109及BHK-21共同培养后,五株恶性肿瘤细胞的增殖均显著受抑,而正常非肿瘤细胞株则不受影响。结论新生大鼠骨骼肌细胞可产生选择性抑制胸部恶性肿瘤细胞增殖的抑瘤物质,这种抑瘤物质可能是临床上骨骼肌内罕见转移瘤现象的生物学基础,并可望因此而诞生一种新的防治肿瘤转移的方法,并最终应用于临床。     

Metabolic and neurologic effects of an intravenous medium-chain triglyceride emulsion

These studies were undertaken to investigate the relationship between medium-chain fatty acid availability, medium-chain fatty acid oxidation, and central nervous system toxicity during infusion of medium-chain triglycerides in dogs. Six dogs received a sequential, stepwise infusion of trioctanoin at three different rates for 80 min each, providing calories below and equal to resting energy expenditure in the species. Ketone body production rates (using a 14C beta-hydroxybutyrate tracer) and plasma concentrations of lactate and octanoate were monitored. Three animals were infused with saline to serve as controls. Blood-brain barrier integrity was assessed with Evans blue dye, and brain samples were taken at the end of the study to quantify brain water. Three animals were studied under anesthesia to obtain good quality EEG and intracranial pressure measurements. Results were (1) plasma octanoate increased to 0.37 +/- 0.13, 0.78 +/- 0.2, and 1.44 +/- 0.41 mmol/liter during the three infusion intervals; (2) emesis, somnolence, and coma were observed at the two highest trioctanoin rates; (3) ketone body concentrations and production increased from 102 +/- 15 to 859 +/- 54 mumol/liter and 3.6 +/- 0.43 to 18.5 +/- 1.7 mumol/kg/min, respectively, at the highest trioctanoin infusion rate; and (4) plasma lactate also increased from 1.3 +/- 0.1 to 4.3 +/- 0.9 mmol/liter at the highest infusion rate. EEG changes were also observed, consisting of high amplitude slowing and reduction in amplitude of faster components. There was no extravasation of Evans blue dye, nor change in brain water or intracranial pressure. The conclusion--medium-chain triglycerides have significant dose-related central nervous system toxicity in dogs. Therefore, caution should be exercised in clinical studies with MCTs, including careful measurement of medium-chain fatty acid concentrations.     

Effect of dietary medium chain triglyceride on lipogenic enzyme activity in rat liver

This study was conducted to confirm that medium chain triglyceride (MCT) feeding itself would increase hepatic lipogenic enzyme activity without causing a lack of essential fatty acids (EFA) in the liver. Male weaning rats were fed for 11 weeks on diets containing 2% corn oil and 13% various fats: MCT, corn oil, tripalmitin or beef tallow, respectively. MCT feeding was clearly shown to increase the activities of fatty acid synthetase (FAS) and malic enzyme (ME) in the liver. Rats weighing 170 g were pair-fed for 7 days on diets containing 15% MCT, 13% MCT + 2% corn oil, 15% corn oil, and 2% corn oil and no fat (control groups), respectively, under a fixed level of carbohydrate (sucrose). The addition of 2% corn oil to MCT (13%) did not depress these enzyme activities, even though supplementing the fat-free diet with 2% corn oil resulted in a significant decline in the activities. When the rats received various amounts of MCT, the extent to which the degree of FAS and ME activities increased by MCT feeding depended on the amount of MCT in the dietary fat mixture with corn oil. Supplement of over 5% corn oil to MCT diets did not inhibit them sufficiently. In the liver lipids of animals fed MCT, there were no appearances of 20:3 omega 9 (5,8,11-eicosatrienoic acid), but the levels of mono-unsaturated fatty acids were increased by MCT feeding. The results suggest that MCT ingestion itself enhances lipogenic enzyme activity via some metabolic charge.     

中链甘油三酯对2型糖尿病胰岛素抵抗的影响

目的探讨中链甘油三酯（MCT）干预对2型糖尿病（T2DM）患者胰岛素抵抗的影响。方法以长链甘油三酯（LCT）为对照,将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,连续食用100％MCT油、50％MCT油＋50％LCT油和100％LCT油3个月。在0、1．5和3个月时检测血浆空腹血糖（FPC）、空腹胰岛素（FIN）、C-肽（CP）、抵抗素（resistin）浓度及β-羟基丁酸浓度,计算胰岛素抵抗指数（HOMA-IR）、胰岛素敏感指数（QUICKI）,并提取外周血单个核细胞进行抵抗素mRNA表达的检测。结果MCT组的FPG水平在1．5个月时较基线降低（P=0．042）;MCT／LCT组的FIN水平在3个月时较基线降低（P=0．005）,在1．5和3个月时MCT／LCT组的FIN水平均低于LCT组（P=0．033,P=0．006）,在1．5个月时MCT组的FIN水平低于LCT组（P=0．020）;MCT组的CP水平在1．5和3个月时均高于基线水平（均P〈0．001）,MCT／LCT组的CP水平在3个月时高于基线水平（P=0．024）;MCT／LCT组的HOMA—IR指数在3个月时低于基线水平（P=0．021）,在1．5个月时MCT／LCT组和MCT组的HOMA-IR指数均低于LCT组（P=0．033,P=0．017）;MCT／LCT组的QUICKI指数在3个月时高于LCT组（P=0．011）。3组的B-羟基丁酸水平在1．5和3个月时差异无统计学意义（P=0．617,P=0．453）。结论在控制总能量和脂肪摄入量的基础上,用MCT取代T2DM患者膳食中50％的食用油3个月,患者的胰岛素抵抗得到改善。     

Replacement of long-chain triglyceride with medium-chain triglyceride/long-chain triglyceride lipid emulsion in patients receiving long-term parenteral nutrition: effects on essential fatty acid status and plasma vitamin K1 levels

BACKGROUND: In long-term parenteral nutrition (LTPN) patients, the use of a 50:50 mixture of medium- and long-chain triglyceride emulsion (MCT/LCT) has been suggested to prevent or correct fatty liver infiltration. However, the use of MCT/LCT lipid emulsion results in a 50% reduction of essential fatty acids and vitamin K1 supply and could induce essential fatty acid and vitamin K1 deficiencies. This study evaluated the effect of a long-term infusion of MCT/LCT lipid emulsion on plasma fatty acid (FA) and vitamin K1 levels on LTPN patients. METHODS: In a prospective nonrandomized crossover study, we measured plasma phospholipid FA composition by gas chromatography and vitamin K1 levels by high-performance liquid chromatography in 11 LTPN patients before and after a 4-month replacement of the usual 20% LCT lipid emulsion (20% Lipoven; Fresenius-Kabi France, Sèvres, France) by a 20% MCT/LCT lipid emulsion (Medialipide B; Braun Medical, Boulogne, France). RESULTS: Patient received LTPN for 46 +/- 40 months; IV lipid emulsion was 827 +/- 336 mL/week. MCT/LCT lipid substitution did not change most of the essential plasma fatty acid concentrations and did not induce essential fatty acid deficiency. With both lipid emulsions, the triene/tetraene (20:3n-9/20:4n-6) ratio remained within the normal ranges. However, with MCT/LCT lipid emulsion, 22:4n-6 (LCT: 0.50 +/- 0.12; MCT/LCT: 0.63 +/- 0.11%) and 22:5n-6 (LCT: 0.32 +/- 0.11; MCT/LCT: 0.48 +/- 0.15%) increased significantly (p = .022 and 0.011, respectively). Plasma vitamin K1 levels decreased drastically with MCT/LCT lipid emulsion. CONCLUSIONS: An amount of 2.85 +/- 1.55 g x kg(-1) week(-1) of MCT/LCT lipid emulsion neither induced essential fatty acid deficiency nor improved the fatty acid disturbances usually observed in LTPN patients but did induce a drop in plasma vitamin K1 levels.     

含膳食纤维和中链三酰甘油的肠内营养制剂在胃癌术后的应用

目的:研究含膳食纤维和中链三酰甘油(MCT)的肠内营养制剂对胃癌手术后病人的作用.方法:随机选取40例胃癌病人,使用含膳食纤维和MCT的肠内营养乳剂,于术后48 h开始,行连续7天的肠内营养支持,热量为125.4 kJ/(kg·d).观察并分析营养支持前后病人的生化指标、营养指标及免疫指标的变化.结果:手术创伤后病人会有营养状况及免疫功能的下降,经营养支持后机体营养状况及免疫功能均有明显改善.结论:对胃癌手术后病人行含膳食纤维和MCT的肠内营养支持可改善营养状况,纠正免疫功能.     

支链氨基酸对创伤后代谢影响的研究

目的:观察应用支链氨基酸对手术创伤病人机体代谢的影响. 方法:采用前瞻、随机、单盲、平行、对照、多中心试验设计,选择行腹部外科手术后成年病人120例,随机分为两组:对照组(n=60)应用10.4% 18种复方氨基酸注射液,研究组(n=60)应用10.3%支链氨基酸注射液.采用全营养混合液方式行周围或中心静脉输注,等氮等热量.从术后第2天开始,应用6天.在手术前1天和术后第7天,对所有病人收集空腹血标本检测,同时进行24 h尿液收集作氮平衡分析. 结果:研究组与对照组之间在研究前、后累积氮平衡无明显差异,但在营养液输注第5天,研究组氮平衡显著高于对照组(P<0.01).两组之间研究前、后血清总蛋白、前清蛋白、纤维连接蛋白、转铁蛋白和体重变化无显著差异.两组研究前、后血清清蛋白浓度均降低,但对照组下降更为明显(P<0.05).研究组应用氨基酸后,缬氨酸浓度升高明显,与对照组相比差异显著(P<0.05).缬氨酸、丙氨酸和支链氨基酸浓度较输注前明显升高(P<0.05). 结论:对手术创伤应激病人的肠外营养支持中,应用含较高支链氨基酸的营养液较平衡氨基酸注射液可能更为有效.     

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.     

The effect of the classical and medium chain triglyceride ketogenic diet on vitamin and mineral levels

Background: The risk of nutritional deficiency in children on restrictive dietary treatments and a lack of ketogenic diet (KD)‐specific UK supplements raises concerns about micronutrient status. Vitamin A, E, zinc, selenium and magnesium levels were therefore examined in children with intractable epilepsy treated with the KD. Methods: Plasma vitamins A and E, zinc, selenium and magnesium levels were measured at baseline and after 3, 6 and 12 months on the classical (n = 46) or medium chain triglyceride (MCT) (n = 45) KD in children aged 2–16 years, as part of a randomised trial, and pairwise comparisons with baseline were performed. Results: Data were available from 91 children. From baseline to 12 months, mean plasma vitamin A decreased from 1.41 μmol L^?1 to 1.13 μmol L^?1 in the classical group (P < 0.001) but increased from 1.52 μmol L^?1 to 1.81 μmol L^?1 in the MCT group (P < 0.001). Mean plasma vitamin E increased from 22.7 μmol L^?1 to 33.2 μmol L^?1 in the classical group (P < 0.001) and from 22.3 μmol L^?1 to 23.3 μmol L^?1 in the MCT group (P < 0.05). No significant change in plasma zinc was seen at 12 months, although mean plasma selenium decreased from 0.95 μmol L^?1 to 0.88 μmol L^?1 in the group as a whole (P < 0.05). Mean plasma magnesium decreased from 0.87 mmol L^?1 to 0.83 mmol L^?1 in the group as a whole (P < 0.001); when subdivided by KD type, this was limited to the classical group. Conclusions: Changes in plasma vitamins A and E and the decline in magnesium status after 12 months of KD treatment suggest that micronutrient status may be suboptimal in this group and that available formulations for KD supplementation may need reviewing.     

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.     

Nutraceutical effects of branched-chain amino acids on skeletal muscle

BCAA catabolism in skeletal muscle is regulated by the branched-chain alpha-keto acid dehydrogenase (BCKDH) complex, located at the second step in the BCAA catabolic pathway. The activity of the BCKDH complex is regulated by a phosphorylation/dephosphorylation cycle. Almost all of BCKDH complex in skeletal muscle under normal and resting conditions is in an inactive/phosphorylated state, which may contribute to muscle protein synthesis and muscle growth. Exercise activates the muscle BCKDH complex, resulting in enhanced BCAA catabolism. Therefore, exercise may increase the BCAA requirement. It has been reported that BCAA supplementation before exercise attenuates the breakdown of muscle proteins during exercise in humans and that leucine strongly promotes protein synthesis in skeletal muscle in humans and rats, suggesting that a BCAA supplement may attenuate muscle damage induced by exercise and promote recovery from the damage. We have examined the effects of BCAA supplementation on delayed-onset muscle soreness (DOMS) and muscle fatigue induced by squat exercise in humans. The results obtained showed that BCAA supplementation prior to squat exercise decreased DOMS and muscle fatigue occurring for a few days after exercise. These findings suggest that BCAAs may be useful for muscle recovery following exercise.     

Reduction-oxidation state and protein degradation in skeletal muscle of fasted and refed rats

Redox state and protein degradation were measured in isolated muscles of fasted (up to 10 d) and refed (up to 4 d) 7- to 14-wk-old rats. Protein degradation in the extensor digitorum longus muscle, but not in the soleus muscle, was greater in the fasted rats than in weight-matched muscle from fed rats. The NAD couple was more oxidized in incubated and fresh extensor digitorum longus muscles and in some incubated soleus muscles of fasted rats than in weight-matched muscle from fed rats. In the extensor digitorum longus muscle of refed or prolonged fasted rats, protein degradation was slower and the NAD couple was more reduced than in the fed state. Therefore, oxidation of the NAD couple was associated with increased muscle breakdown during fasting, whereas reduction of the NAD couple was associated with muscle conservation and deposition.     

Metabolism of defined structured triglyceride particles compared to mixtures of medium and long chain triglycerides intravenously infused in dogs

The present study aimed to determine whether including medium-chain fatty acids (MCFA) in specifically designed structured triglycerides (STG) with a MCFA in sn-1 and sn-3 positions and a long-chain (LC) FA in sn-2 position (MLM) would lead to different effects on plasma lipids and FA distribution into plasma and tissue lipids by comparison to a mixture of separate MCT and LCT molecules (MMM/LLL). The fatty acid (FA) composition was comparable in both lipid emulsions. Lipids were infused over 9h daily, in 2 groups of dogs (n = 6 each), for 28 days as a major component (55% of the non-protein energy intake) of total parenteral nutrition (TPN). Blood samples were obtained on specific days, before starting and just before stopping TPN. The concentration of plasma lipids was measured before starting and before stopping TPN on days 1, 2, 3, 4, 5, 8, 10, 12, 16 and 28. Biopsies were obtained from liver, muscle and adipose tissue 15 days before starting, and again on the day following cessation of TPN. In addition, the spleen was removed after the TPN period. FA composition in plasma and tissue lipids was analysed by gas liquid chromatography in different lipid components of plasma and tissues. No differences in either safety or tolerance parameters were detected between both lipid preparations. A lower rise of plasma TG (P < 0.05) was observed during MLM infusion, indicating a faster elimination rate of MLM vs MMM/LLL emulsion. In spite of the differences of TG molecules which would be assumed to affect the site of FA delivery and metabolic fate, FA distribution in phospholipids (PL) of hepatic and extrahepatic tissues did not substantially differ between both emulsions.     

鱼油脂肪乳对胃肠道恶性肿瘤病人术后营养状况和体液免疫的影响

目的:观察鱼油脂肪乳对胃肠道恶性肿瘤病人术后营养状况和体液免疫的影响. 方法: 将30例胃肠道恶性肿瘤病人随机分为研究组和对照组,每组15例.术后两组病人使用等氮、等热量的PN支持,研究组添加鱼油脂肪乳.于术前、术后第1天和第6天分别检测血肝肾功能、血脂、Hb、ALB、TF、淋巴细胞计数(TLC)、B淋巴细胞亚群(B1、B2)、免疫球蛋白(IgG、IgM、IgA)和补体(C3、C4)水平. 结果: 两组病人术后第6天肝肾功能、血脂水平与术前相比均无显著性差异.研究组病人术后第6天TLC、IgG、IgM、C3显著高于对照组(P<0.05).两组病人Hb、ALB、TF和B淋巴细胞亚群无显著性差异. 结论: 胃肠道恶性肿瘤病人术后使用鱼油脂肪乳安全可耐受,能提高体液免疫功能,但在短期内病人的营养状况未见改善.     

脂肪乳剂对胃癌病人术后免疫功能的影响

将31例因胃癌行全胃切除术后静脉营养病人随机分为无脂组、低脂组、高脂组，观察术前、术后T淋巴细胞亚群、IL－2、IL－6、sIL－2R变化。结果术前、术后1、3、5天各组间无差异，术后7天，高脂组CD4低于其它两组，CD4／CD8降低；IL－2、IL－6比其它两组低；sIL－2R升高。提示大剂量长期输注脂肪乳剂可能对免疫功能有影响，而低脂组没有。