Effects of medium-chain and long-chain triacylglycerols in pediatric surgical patients

Medium-chain triacylglycerols (MCTs) have been shown to provide better nutritional support than long-chain triacylglycerols (LCTs). This study compares the efficacy of MCT combined with LCT with LCT alone in pediatric patients with surgical stress. Two groups of patients (n = 19 in each) received equivalent amounts of glucose (12 g. kg. d) and amino acids (2 g. kg. d), but one group received 10% Lipofundin MCT/LCT and the other received 10% LCT (1.5 g. kg. d) in a randomized study. Total parenteral nutrition (TPN) was given for 14 d. Blood and urine samples were collected before and after TPN administration for determination of various biochemical parameters. Indirect calorimetry was also performed to determine respiratory quotients and fuel utilization. After 14 d of TPN in the MCT/LCT group, there was a significantly higher blood lymphocyte percentage, a decreasing tendency of serum asparate aminotransferase and of total and direct bilirubin (P < 0.05). These changes were not observed in the LCT group. A significantly better nitrogen balance and a higher ketogenesis from day 3 were observed in the MCT/LCT group. The MCT/LCT group showed a more marked increased utilization of fat than the LCT group, whereas carbohydrate oxidation was less in the MCT/LCT group than in the LCT group (P < 0.05). In children after surgery, MCT/LCT is more protein sparing and induces a better immune response when compared with LCT-containing lipid emulsion. A TPN regimen containing MCT/LCT is likely to result in rapid oxidation of fats for energy without compromising the respiratory system.     

Brain lipid composition in rabbits after total parenteral nutrition with two different lipid emulsions

ObjectiveTo study the changes occurring in brain lipid composition after the administration of total parenteral nutrition (TPN) by comparing two lipid emulsions, one with long-chain triacylglycerols (LCT) and the other with long-chain and medium-chain triacylglycerols (MCT/LCT 50%/50%).MethodsWe used 21 young New Zealand rabbits divided into three groups of seven animals each. Two groups were subjected to TPN for 7 d, with each group receiving using one of two different lipid emulsions: Intralipid 20% (group LCT) and Lipofundin MCT/LCT 20% (group MCT/LCT). The third control group received an oral diet and underwent the same surgical procedure with the administration of intravenous saline solution. The energy administered in the TPN formulas was non-protein 100 kcal ? kg^?1 ? d^?1, with 40% corresponding to fats.ResultsThere were modest increases in plasma cholesterol and triacylglycerols. In the brain tissue, there was a decrease of phosphatidylcholine in animals with TPN, which was greater in group LCT. There were no significant differences in the overall percentage distribution of brain fatty acids among the groups.ConclusionThe lipid emulsions administered in TPN, especially those prepared exclusively with LCT, cause changes in the brain lipid polar fractions of young rabbits.     

The Henry M. Vars Award. The effect of lipid emulsions on reticuloendothelial system function in the injured animal

Use of intravenous lipid emulsions in trauma and sepsis still remains controversial. In order to examine the impact lipid emulsions have on host defense against bacterial infection during total parenteral nutrition (TPN), 56 male Sprague-Dawley rats underwent jugular cannulation and were randomly divided into three groups, each receiving one of three TPN regimens. All regimens delivered approximately 250 kcal/kg X body weight/day, of which 12.5 g were as amino acids. Group 1 received 100% of the nonprotein calories as glucose (AA + G). Group 2 was given 50% of the nonprotein calories as a longchain triglyceride emulsion (100% LCT). Group 3 received 50% of nonprotein calories as a mixed lipid system, composed of medium- and long-chain triglycerides (75% MCT/25% LCT). After 24 hr on intravenous nutrition, all animals received bilateral septic femur fractures and were continued on TPN for 3 days. On the last day, the level of bacteremia and the in vivo response to an intravenous challenge of 59Fe-labeled Escherichia coli were examined. Three days following the septic injury, animals given MCT as part of their lipid calories were not bacteremic, whereas the other groups had greater than 10(2) cfu/ml of blood. Animals receiving TPN with MCT sequestered a greater percentage of exogenously administered bacteria in the liver and sequestered less in the lung compared to animals given 100% LCT (p less than 0.05). From these data, we conclude that parenteral nutrition formulas where LCT has been partially replaced with MCT may better support host bactericidal capacity than similar regimens comprised of LCT as the sole lipid source.     

Effect of Medium-Chain Triglyceride Emulsion in Total Parenteral Nutrition on Experimental Hepatic Metastasis in the Rat

Background: This study evaluated the effect of total parenteral nutrition (TPN) regimens containing a medium-chain triglyceride (MCT) emulsion on tumor metastasis. Methods: Tumor metastasis development was assessed by the number of metastatic foci on the liver surface in rats inoculated with ACL-15 tumor cells via the portal vein. Rats received one of the following TPN regimens: TPN containing an MCT emulsion (group M), in which tricaprylin emulsion served as the MCT and comprised 50% of nonprotein calories (NPC); TPN containing a long-chain triglyceride (LCT) emulsion (group L), in which soybean oil served as the LCT and comprised 50% of NPC; and TPN without lipid emulsion (group G), in which dextrose comprised 100% of NPC. Results: The number of metastatic foci was greatest in rats receiving TPN containing the MCT emulsion on day 11 after tumor cell inoculation and either 11 days of TPN or 2 days of TPN followed by 9 days standard rat chow. Conclusions: TPN containing MCT emulsion increases liver metastasis early in its administration. (Journal of Parenteral and Enteral Nutrition 21:220–223, 1997)     

Effect of various lipid emulsions on total parenteral nutrition-induced hepatosteatosis in rats

The effect of various lipid emulsions on the development of fatty liver during total parenteral nutrition (TPN) was investigated in rats given TPN for 7 days. Medium-chain triglycerides (MCT), long-chain triglycerides (LCT), chemically defined triglycerides (CDT; structured lipid with a high purity of 94.3%), and a mixture of MCT and LCT (MIX) were prepared as the lipid emulsions. TPN provided 350 kcal/kg/day, with a nonprotein calorie/nitrogen ratio of 160. The TPN-1 group received 10% nonprotein calories and the TPN-2 group received 30% nonprotein calories. MCT TPN was found to have some disadvantages, especially with regard to nitrogen balance and plasma albumin levels. Total cholesterol and phospholipids tended to be high in the MCT TPN group. The hepatic lipid content was higher in the lipid-free TPN and the MCT TPN groups, and lower in the CDT and LCT TPN groups. Histologically, the livers of the MIX, CDT, and LCT TPN groups showed less fatty change than those of the FREE and MCT groups.     

Effects of parenteral structured lipid emulsion on modulating the inflammatory response in rats undergoing a total gastrectomy

OBJECTIVES: Structured lipid emulsion improves the nitrogen balance and is rapidly cleared from the blood of moderately catabolic patients. However, the effects of structured lipids on inflammatory reactions during major surgery are not clear. This study investigated the effect of a parenteral structured triacylglycerol emulsion on leukocyte adhesion molecule expression and inflammatory mediator production in rats undergoing a total gastrectomy. METHODS: Normal rats with internal jugular catheters were assigned to three experimental groups and received total parenteral nutrition. At the same time, a total gastrectomy was performed on the experimental groups. The total parenteral nutrition solutions were isonitrogenous and identical in nutrient compositions except for differences in the composition of the fat emulsion. Group 1 received a conventional fat emulsion with long-chain triacylglycerols (LCTs), group 2 received a physical mixture of medium-chain triacylglycerols (MCTs) and LCTs (MCT/LCT), and group 3 received structured lipids composed of MCTs and LCTs (STG). Half of the rats in each respective group were sacrificed 1 d and the other half 3 d after surgery to examine the analytical parameters. RESULTS: Plasma cholesterol and free fatty acid levels in the STG group were lower than those in the other groups after surgery. The STG group had lower leukocyte CD11a/CD18 expressions than the MCT/LCT group 3 d after surgery, and CD11b/CD18 expressions in the STG group were lower than those in the LCT group on postoperative days. The STG group had higher monocyte chemotactic protein-1 and macrophage inflammatory protein-2 levels in peritoneal lavage fluid than did the other two groups. CONCLUSION: These results suggest that, compared with the LCT and MCT/LCT groups, rats administered STG had lower plasma lipid concentrations and leukocyte integrin expressions. In addition, STG administration may cause increased recruiting of neutrophils and monocytes at the site of injury and enhance antipathogenicity in rats undergoing a total gastrectomy.     

Effects of medium-chain triglyceride in parenteral nutrition on rats undergoing gastrectomy

This study was designed to investigate the effects of pre-infusion with total parenteral nutrition (TPN) using medium-chain triglyceride (MCT) versus long-chain triglyceride (LCT) emulsion as fat sources on hepatic lipids, inflammatory mediators and antioxidant capacity in rats undergoing gastrectomy. Rats with internal jugular catheter, were divided into two groups and received TPN. TPN supplied 300 kcal/kg/d with 39% of the energy provided as fat. All TPN solutions were isonitrogenous and identical in nutrient composition except for the fat emulsion, which was composed of MCT/LCT (1 : 1) or LCT. After receiving TPN for 5 days, the rats underwent partial gastrectomy and were sacrificed 24 h after surgery. The results of the study demonstrated that the MCL/LCT group had lower hepatic lipids than did the LCT group. No differences in interleukin-1beta, interleukin-6 and tumor necrosis factor-alpha in peritoneal lavage fluid were observed between the two groups. Erythrocyte glutathione peroxidase activity was significantly higher in the LCT group than the MCT/LCT group, although erythrocyte superoxide dismutase activity did not differ significantly between the two groups. These results suggest that infusion with MCT/LCT before an abdominal operation did not have an effect on modulating the production of inflammatory mediators in the location of the injurious stimulus. However, pre-infusion with MCT/LCT have beneficial effect in improving liver lipid metabolism and reducing oxidative stress in rats with gastrectomy.     

Changes of hepatic morphology during parenteral nutrition with lipid emulsions containing LCT or MCT/LCT quantified by ultrasound.

Fatty infiltration of the liver with cholestasis is one of the complications of total parenteral nutrition (TPN). The cause has not yet been determined. It seems probable, however, that these alterations could be prevented when a mixture of medium- and long-chain triglycerides (MCT/LCT) is used as a fat component instead of the application of long-chain emulsions (LCT) alone. To determine whether this could also be demonstrated morphologically in man, 14 patients needing TPN (25 kcal/kg BW x day, carbohydrate 45%, fat 35%, protein 20%) were examined by ultrasound in order to compare liver size and gray-scale value before and after 7 days of TPN. Seven of the patients were randomly administered a MCT/LCT emulsion as their fat intake, the other seven were exclusively given LCT. There were no changes in liver size and gray-scale value in the MCT/LCT-group, whereas both parameters showed a significant rise in the patients with LCT (size: 10.4 +/- 1.4 to 11.5 +/- 1.4 cm; gray-scale value: 9.3 +/- 1.0 to 11.6 +/- 0.7). These data suggest that TPN, administered with a mixture of MCT/LCT emulsions as fat components, could reduce the risk of hepatic dysfunction such as cholestasis and fatty infiltration of the liver.     

Manipulation of tissue fatty acid profile by intravenous lipids in dogs

This study was undertaken to determine the effects on the fatty acid (FA) composition of various dog tissues of 4 different lipid emulsions (a 100% long-chain triacylglycerol (LCT) derived from soya bean oil emulsion, a mixed 50% medium-chain triacylglycerol (MCT)/50% LCT emulsion as well as both these emulsions supplemented with 10% fish oil (FO) triacylglycerols), when daily infused over 15 days as a substantial component of total parenteral nutrition. Lipids represented 55% of the non-protein energy. Blood samples as well as biopsies from liver, muscle and adipose tissue were taken 15 days before, and again immediately after TPN. In addition, the spleen was also removed immediately after TPN. Tissue FA composition was analysed by gas liquid chromatography of each lipid component after separation by thin layer chromatography. No differences in either safety or tolerance were detected between the different TPN preparations. In particular, infusion over 2 weeks of fat emulsions containing 10% fish oil was tolerated as well as conventional LCT and MCT/LCT emulsions. Relative linoleate content of tissue triacylglycerol (TG) was markedly increased in animals that received the LCT emulsions (e.g. from 22.6 +/- 2.5% to 32.2 +/- 0.6% in the liver), this effect being markedly reduced with MCT/LCT preparations. n-3FA were slightly incorporated into liver TG (from 0.0 +/- 0.0% to 2.3 +/- 0.7% and 1.2 +/- 0.4% for eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) respectively, with LCT + FO), but remained undetectable in extrahepatic tissue TG. Of interest, medium chain FA were found in tissue TG after infusion of the mixed MCT/LCT emulsions. As expected, changes of tissue phospholipid (PL) composition involved only long-chain FA. Infusion of soya bean oil emulsion was associated with an increased content of linoleate in liver PL (from 13.6 +/- 0.4% to 17.7 +/- 0.4%), but not in other tissues. MCT/LCT did not markedly affect PL/FA pattern in any tissue. Supplementation with fish oil was associated with an efficient incorporation of n-3FA into tissue PL, particularly in the liver (from 0.4 +/- 0.1% to 2.5 +/- 0.3% for EPA and from 3.9 +/- 0.8% to 9.1 +/- 0.4% for DHA, with the LCT + FO emulsion).     

Effects of intravenous supplementation with alpha-tocopherol in patients receiving total parenteral nutrition containing medium- and long-chain triglycerides

OBJECTIVE: To compare the effects of a lipid emulsion containing medium-chain triglycerides (MCT) and supplemented with alpha-tocopherol to a conventional long-chain triglyceride (LCT) emulsion. DESIGN: Randomised double blind study. SETTING: Department of Internal Medicine, Antwerp University Hospital. SUBJECTS AND INTERVENTIONS: Twenty-four patients with an indication for total parenteral nutrition for a minimum of 10 days were randomly assigned to two groups: group E received as lipid source MCT/LCT (50/50) suplemented with 100 mg DL-alpha-tocopherol/day and group C received LCT. Blood samples were analysed at inclusion, after 4-6 and after 9-11 days. RESULTS: In group E, serum alpha-tocopherol doubled from 11.4+/-6.9 at inclusion to 20.9+/-7.9 and to 23.8+/-8.8 microg/ml after 4 and 9 days, respectively, but did not change in group C (P=0.008). Production of thiobarbituric acid-reacting substances (TBARS) after 120 min incubation with copper decreased from 66+/-34 at inclusion to 29+/-25 nmol MDA/mg LDL and VLDL-cholesterol after 4 and to 42+/-17 after 9 days (P=0.022 when compared to group C, which underwent no significant changes). Velocity of production of fluorescent products decreased in group E but not in group C (P=0.026). CONCLUSIONS: Supplementation of TPN containing MCT/LCT with 100 mg DL-alpha-tocopherol/day leads to a doubling in serum alpha-tocopherol and to a decrease in the susceptibility of LDL and VLDL to peroxidation in vitro. SPONSORSHIP: This study was partly financed by B Braun Medical NVSA, Diegem, Belgium.     

Antioxidant status of surgical patients receiving TPN with an omega-3-fatty acid-containing lipid emulsion supplemented with alpha-tocopherol

BACKGROUND: LCT lipid emulsions and even more fish oil-containing lipid emulsions are under debate regarding their tocopherol and PUFA content as well as their effect on the antioxidative status especially in patients with oxidative stress. METHODS: Thirty-three patients undergoing major abdominal surgery were randomly assigned to receive either an alpha-tocopherol-supplemented (562 micromol/l) MCT/LCT/omega-3-acid triglycerides (MLF, 5/4/1 w/w/w, 20%) emulsion or a soybean oil-based LCT emulsion (20%). The TPN regimen continuously provided 1.4 g fat kg bw(-1)d(-1)over 5 days. RESULTS: Plasma antioxidant concentrations were strongly reduced by surgical treatment. Following 5 days of TPN with the MLF emulsion, mean plasma alpha-tocopherol increased by 20.0 micromol/l (1.98 micromol/mmol lipid), while nearly no change was observed in the LCT emulsion group. In both groups, plasma concentrations of all non-supplemented antioxidants (vitamin C, carotenoids, selenium) as well as serum total antioxidant capacity further decreased during TPN. The concentrations of plasma cholesterol oxidation products as a measure of in vivo lipid peroxidation revealed no changes over the TPN period in either group. CONCLUSION: In contrast to the LCT emulsion, administration of the a-tocopherol supplemented MLF lipid emulsion normalized a-tocopherol plasma concentrations. Despite its high long-chain PUFA content, no hint for increased lipid peroxidation was found.     

Effects of a medium-chain triacylglycerol/long-chain triacylglycerol fat emulsion containing a reduced ratio of phospholipid to triacylglycerol in pediatric surgical patients

OBJECTIVE: Medium-chain triacylglycerol (MCT) has been shown to provide better nutritional support than long-chain triacylglycerol (LCT). We compared the efficacy of MCT/LCT fat emulsions containing a usual (0.12) or a decreased (0.06) ratio of phospholipid to triacylglycerol (PL:TG) in pediatric patients under surgical stress. METHODS: Three patient groups (n=10 in each) received equivalent amounts of glucose (12 g.kg(-1).d(-1)) and amino acids (2 g.kg(-1).d(-1)), but group A received a 10% MCT fat emulsion (PL:TG 0.06), group B received a 20% MCT fat emulsion (PL:TG 0.06), and group C received a 10% MCT/LCT fat emulsion (PL:TG 0.12) in amounts of 1.5 g.kg(-1).d(-1) in a randomized study. Total parenteral nutrition was given for 7 d. Blood samples were collected before total parenteral nutrition administration and on days 4 and 7 for determination of various biochemical indexes. RESULTS: Serum phospholipid concentrations were significantly higher in group C than in group A or B on days 4 and 7 (P<0.05). Serum triacylglycerol and cholesterol concentrations and the very-low-density lipoprotein percentage were also significantly higher in group C than in group A or B on days 4 and 7 (P<0.05). The high-density lipoprotein percentage was significantly higher in group B on days 4 and 7 (P<0.05). CONCLUSIONS: In pediatric patients under surgical stress, a total parenteral nutrition regimen containing an MCT/LCT fat emulsion with a decreased PL:TG ratio (0.06) is likely to result in partly better lipid and lipoprotein metabolism than an emulsion containing the usual ratio (0.12).     

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.     

Effects of three intravenous lipid emulsions on the survival and mononuclear phagocyte function of septic rats

The immunosuppressive effects of intravenous lipid emulsions are a matter of great concern and debate. In a rat model of gram-negative bacteremia, we assessed whether the use of three intravenous lipid emulsions with different triacylglycerol compositions could influence mortality, bacterial clearance, and prostaglandin E(2) (PGE(2)) levels and compared these groups with groups of orally fed rats and rats that received a small amount of calories in form of glucose without enteral feeding (starvation).RATS WERE ASSIGNED TO ONE OF FIVE GROUPS: group 1 (control, n = 15) received rodent chow ad libitum and saline infusion; group 2 (starvation group, n = 12) had no access to chow and received an infusion of 5% glucose; group 3 (n = 17) received total parenteral nutrition (TPN) with long-chain triacylglycerols; group 4 (n = 12) received TPN with medium- and long-chain triacylglycerols; and group 5 (n = 15) received TPN with its emulsion based on olive oil. Animals received isonitrogenous and isocaloric TPN. After 2 d of TPN, a dose of 10(8) colony-forming units of Escherichia coli was introduced via the venous catheter; 2 d later the animals were killed. Blood, spleen, liver, and lungs were cultured. Circulating levels of PGE(2) were measured.Bacterial growth in the liver and lungs were significantly higher in groups 3 and 4 than in group 1, with no differences among the other groups. Rates of bacteremia were significantly higher in groups 3 and 4 than in group 1, with no differences among the other groups. Plasma levels of PGE(2) did not differ, and mortality was unaffected.Bacterial clearance clearly was preserved in orally fed, control rats when compared with rats on TPN with long-chain triacylglycerols or medium- plus long-chain triacylglycerols. However, the use of a lipid emulsion enriched intravenously with oleic acid was a valid way of reducing this disturbance, although plasma levels of PGE(2) and survival were not modified.     

Parenteral nutrition providing a restricted amount of linoleic acid in severely burned patients: a randomised double-blind study of an olive oil-based lipid emulsion v. medium/long-chain triacylglycerols

It has been claimed that lipid emulsions with a restricted linoleic acid content can improve the safety of total parenteral nutrition (TPN). The tolerability of TPN and its effects on the metabolism of fatty acids were assessed in this prospective, double-blind, randomised study comparing an olive/soyabean oil long-chain triacylglycerol (LCT) with a medium-chain triacylglycerol (MCT)/LCT; 50:50 (w) based lipid emulsion in two groups (O and M, respectively; eleven per group) of severely burned patients. After resuscitation (48-72 h), patients received TPN providing 147 kJ/kg per d (35 kcal/kg per d) with fat (1.3 g/kg per d) for 6 d Plasma fatty acids, laboratory parameters including liver function tests, and plasma cytokines were assessed before and after TPN. Adverse events encountered during TPN and the clinical outcomes of patients within the subsequent 6 months were recorded. With both lipid emulsions, the conversion of linoleic acid in its higher derivatives (di-homo-gamma-linolenic acid) improved and essential fatty acid deficiency did not appear. Abnormalities of liver function tests occurred more frequently in the M (nine) than in the O (three) group (P = 0.04, Suissa-Shuster test). Seven patients (four from group O and three from group M) died as a consequence of severe sepsis 3-37 d after completion of the 6 d TPN period. When compared with the surviving patients, those who died were older (P = 0.01) and hyperglycaemic at baseline (P < 0.001), and their plasma IL-6 levels continued to increase (P < 0.04). Although fatty acid metabolism and TPN tolerability were similar with both lipid emulsions, the preservation of liver function noted with the use of the olive oil-based lipid emulsions deserves confirmation.     

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 structured lipids as energy substrate after hepatectomy in rats with streptozocin-induced diabetes.

The suitability of energy substrates for use by the remnant liver after 70% hepatectomy was studied in relation to the hepatic energy status in diabetic rats. Rats with streptozocin-induced diabetes underwent 70% hepatectomy and were divided into five groups receiving total parenteral nutrition (TPN) for 24 h. One group received standard TPN without fat, and four groups respectively received standard TPN with long-chain triglycerides (LCTs), medium-chain triglycerides (MCTs), mixed triglycerides (MIX), or structured lipids (SLs) as a 10% lipid emulsion. The latter groups received 60% of nonprotein calories per day with fat emulsion (LCT, MCT, MIX, or SL), and the remaining 40% with glucose. The group that received 100% of nonprotein calories per day with glucose was defined as the TPN group. All rats in the TPN group died from nonketotic hyperosmolarity within 24 h. The blood ketone body ratio (acetoacetate/beta-hydroxybutyrate), the energy charge level of the remnant liver, and the cumulative excretion of 14CO2 in expired breath during 6 h after [14C]glucose administration were all significantly higher in the SL group than in the other groups 24 h after hepatectomy. These findings suggest that SL may be a superior energy substrate to other triglyceride preparations during the immediate posthepatectomy phase in diabetic patients.     

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.     

含中链甘油三脂的脂肪乳剂有利于胃切除术后大鼠的脂类代谢和抗氧化能力

研究胃切除大鼠于术前接受以中链甘油三酯或长链甘油三酯为脂肪来源的肠外营养对肝内脂类，炎性介质和抗氧化能力的影响。大鼠经颈内静脉插管，分成两组接受肠外营养治疗。肠外营养的能量为30kcal/kg/d， 脂肪占能量的39％。除了脂肪乳剂外所有肠外营养制剂都是等氮的并含有相同的营养成分，脂肪乳剂的成分中链／长链（1：1）或长链脂肪乳剂。大鼠于接受肠外营养5天后经部分胃切除术，于术后24小时处死。研究结果显示，中逻／长链组肝内脂肪少于长链组。提示中链／长链脂肪乳剂能改善肝脏脂类代谢。两组大鼠的腹腔灌洗液（PLF）和血液中白介素－1β（Ⅱ-1β），白介素－6（Ⅱ－6）和肿瘤坏死因子α（TNF－α）无显差别，说明术前输入中链／长链脂肪乳剂对调节大鼠循环血液中的炎性介质和手术刺激没有影响。长链脂肪乳剂组的红细胞谷胱甘肽超氧化物酶（GSHPx)的活力明显高于输入中链／长链脂肪乳剂组，但红细胞超氧化物歧化酶（SOD）的活力在两组之间无显性差别。这些结果说明，腹部手术前输入中链／长链脂肪乳剂能改善脂类代谢和减少氧化物的刺激。结论：推荐对准备行胃手术的肠外营养支持的病人使用中链／长链脂肪乳剂。     

Lipid infusion with different triglyceride cores (long-chain vs medium-chain/long-chain triglycerides): effect on plasma lipids and bilirubin binding in premature infants.

The possible beneficial effects of infusing a lipid emulsion containing 50% by weight of medium-chain triglycerides (MCT) compared with a standard long-chain triglyceride (LCT) emulsion were studied in 18 premature neonates (gestational age less than 34 weeks) requiring parenteral nutrition. The infants were assigned in a double-blind manner to receive one of the two lipid emulsions over 17 hours a day as a supplemental regimen for total parenteral nutrition. A lipid load of 1 g/kg per day was initiated on the third day of life and was increased at the rate of 1 g/kg per day until a maximal dose of 3 g/kg per day was obtained on the fifth day of life and maintained thereafter. Both bound and unbound bilirubin decreased with both infusion regimens during the study period. Despite a marked increase in plasma free fatty acid levels (260% in the MCT/LCT group compared with 210% in the LCT group), the fraction of unbound (free) bilirubin was significantly lower in the MCT/LCT group (34% vs 13%). Free fatty acid levels, corrected to albumin, were positively correlated to the percentage of free bilirubin only for the LCT lipid infusion. The finding of a significant elevation of plasma cholesterol levels only in the MCT/LCT group is now under investigation. Use of the MCT-containing emulsion was not associated with a higher frequency of adverse effects than the commonly used LCT-containing emulsion.(ABSTRACT TRUNCATED AT 250 WORDS)