Fat elimination in parenterally fed low birth weight infants during the first two weeks of life

Eighteen low birth weight infants (27-34 wk gestation) were given supplementary parenteral nutrition via peripheral veins of a maximal dose of 8.5 g glucose, 2.5 g amino acids (Aminoven?s p?d 10%) and 2 g soybean oil egg lecithin emulsion (Intralipid 10%) kg body weight/24 hr. The fat emulsion was infused continuously at a rate of 0.084 g/kg body weight/hr. The elimination of Intralipid from the blood stream was controlled by enzymatic determination of serum triglyceride concentrations, and the fatty acid pattern of the serum lipids was determined by gas chromatography. The serum triglyceride concentrations were 0.60 +/- 0.16 mmol/liter on the 1st day, increased to 0.96 +/- 0.29 mmol/liter up to the 5th day, and approached a level around 0.90 mmol/liter in the further course. No hypertriglyceridemia was noted. The fatty acid pattern of the serum lipids showed a linoleic acid fraction of 8.1 +/- 4.0% in the beginning, which was followed by a continuous increase up to 27.8 +/- 4.8% on the 7th day. No significant changes were noticed thereafter. The levels were within the normal limits as found in 2-wk-old enterally fed preterm infants of comparative maturity (25.6 +/- 3.4%). We conclude that the preterm infants can eliminate Intralipid from the blood stream if maximal dosage and infusion rate, as described above, are applied.     

Impaired fat utilization in parenterally fed low-birth-weight infants suffering from sepsis

Lipid infusion in low-birth-weight infants suffering from sepsis is still controversial. Consequently, we investigated the fat tolerance in six low-birth-weight infants with sepsis and 15 low-birth-weight infants without sepsis. For measurement of fat clearance, we assayed the serum concentrations of triglycerides enzymatically, and of the free fatty acids by colorimetric micromethod. The fatty acid oxidation was analyzed with the [13C]triolein breath test by means of ratio-mass spectrometry. The infants were maintained on continuous parenteral nutrition with various amounts of soybean oil emulsion (1 g, 2 g, and 3 g fat/kg body weight per day). Comparing the lipid infusion of 1 and 2 g fat/kg body weight per day between the two groups, we found triglyceride and free fatty acid values in both groups to be in the normal range. At a dose of 3 g of fat/kg body weight per day, septic low-birth-weight infants showed a significantly higher concentration of triglycerides (2.02 +/- 0.46 mmol/liter) and of free fatty acids (2.06 +/- 0.45 mmol/liter) than the nonseptic low-birth-weight infants (triglycerides: 1.09 +/- 0.43 mmol/liter; free fatty acids: 1.05 +/- 0.41 mmol/liter). The low-birth-weight infants with sepsis showed a reduced fat oxidation rate of 16.0 +/- 1.5% in contrast to that of the low-birth-weight infants without sepsis, whose rate was 38.4 +/- 1.8%. Accordingly, we apply dosages not exceeding 2 g of fat/kg body weight per day to septic low-birth-weight infants.     

Comparative clearance of two new fat emulsions--Hausmann Lipid 20% and Lipoven?s 20%--versus intralipid 20%

Intravenous fat tolerance tests (IVFTT) were performed in 13 healthy men volunteers once a day during three consecutive days in order to compare three different fat emulsions randomly administered (Intralipid 20%, Hausmann Lipid 20%, Lipoven?s 20%). The amount of fat was 0.1 g/kg of body weight injected within 32 +/- 4 sec and the lipid clearance was determined over 40 min. The fractional removal rates k for the three different emulsions of fat were 5.38 +/- 1.67, 4.95 +/- 2.15, 3.92 +/- 1.31 %/min, respectively (mean +/- SD), and the half-life time of clearance T1/2 were 14.5 +/- 5.8, 16.9 +/- 7.4, 19.2 +/- 5.2 min, respectively. The highest fat particles values were observed 5 min after the bolus and all concentrations remained within the normal range (0-3 g/liter) during the study. In addition, no adverse effects were observed throughout the IVFTT. The nonparametric analysis of variance (Friedman's test) showed no significant differences between groups, even if Lipoven?s 20% tended to be cleared more slowly than Intralipid 20%. These results suggest that the three fat emulsions are similarly eliminated from the blood stream and do not result in acute intolerance. Further studies based on prolonged infusion should be carried out to determine whether the two new emulsions might be alternatively used for intravenous nutritional support.     

Lipid infusion in premature infants suffering from sepsis

In as much as possible side effects attributing to insufficient fat clearance with hyperlipemia, parenteral lipid administration to septic premature infants is controversial. In this study serum triglyceride and free fatty acid concentrations of nine low birth weight infants with septicemia and 21 low birth weight infants without septicemia were measured. Acidosis, hypoxia, hyperglycemia, and cardiovascular insufficiency were treated before parenteral lipid infusion was started. There was no occurrence of septic shock. In the course of fat infusion with 3 g/kg body weight per day in low birth weight infants without systemic infection we only found triglyceride concentrations of 1.15 mmol/liter and free fatty acid levels of 1.05 mmol/liter. Premature infants with septicemia showed, under fat application of 2 g/kg body weight per day, mean triglyceride levels of 1.67 mmol/liter and free fatty acid values of 1.94 mmol/liter. The highest concentrations occurred at 3 g fat/kg body weight per day with triglycerides of 2.02 mmol/liter and free fatty acids of 2.06 mmol/liter. They indicate a reduced clearance and support earlier findings of reduced utilization of infused fat in premature infants with septicemia. Triglyceride concentrations more than 1.7 mmol/liter probably induce an increase of phagocytosis of the fat particles with the effect of a partial block of the reticuloendothelial system and an impairment of pulmonary diffusion capacity. Therefore, we suggest dosages no higher than 2 g fat/kg body weight per day to low birth weight infants and we advise to check the triglycerides daily. Hypertriglyceridemia implicates an immediate reduction or total interruption of the lipid infusion until normal triglyceride values are regained.     

Effects of long-chain triglyceride emulsions on reticuloendothelial system function in humans

Parenteral administration of long-chain triglyceride emulsions has been shown to have deleterious effects on reticuloendothelial system function in animal models. It is unknown whether this interference occurs in humans with clinically relevant doses of intravenous fat. Two studies were done. Eighteen patients were prospectively enrolled for study. Patients received full feeding by continuous total parenteral nutrition (amino acids 1.5 g/kg/day and dextrose 4.5 g/kg/day) with 33.1 kcal/kg/day. Forty-three % of the nonprotein calories were provided as soybean oil emulsion (Travamulsion 20%) and was administered intravenously over 10 hr (0.130 g/kg/hr). Reticuloendothelial system function was determined by measuring the change in the clearance rate of intravenously injected 99mTc-sulfur colloid (TSC) in each patient. In study 1 (n = 10), one day of lipid (10 hr) was infused, with the clearance of 99mTc-sulfur colloid measured before the lipid was infused and then during the last hour of the 10-hr infusion. In study 2 (n = 8), the clearance rates were measured before the lipid emulsion was begun, and then during the last hour of the infusion on the 3rd day. Clearance rates for TSC after 10 hr of lipid infusion in study 1 did not differ (0.27 +/- 1/min to 0.26 +/- 0.1/min, p greater than 0.10). However, after 3 days of lipid infusion (10 hr/day), a statistically significant reduction in TSC was seen (0.46 +/- 0.08/min-0.27 +/- 0.03/min, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Elimination and metabolism of a fat emulsion containing medium chain triglycerides (lipofundin MCT 10%)

Medium chain triglycerides (MCT) are supposed to be advantageous on account of rapid energy supply in parental nutrition. However, data on the elimination rate of MCT-containing emulsions during an intravenous fat-tolerance test (IVFTT) are scarce. We performed this test (0.1 g lipid/kg body weight) in 18 young healthy volunteers (nine females and nine males) using Lipofundin MCT 10% (50% MCT; egg phospholipids as emulsifier). Our results indicate that both elimination and metabolization of the emulsion are fast: a prompt decrease of light-scattering index and of triglyceride concentrations in serum, an immediate appearance of post-load fatty acids and of beta-hydroxybutyrate were observed. This was in good agreement with the findings obtained during 6-hr infusions in the same probands. Fractional elimination rates k2 obtained from light-scattering indices are 7.29 +/- 2.73%/min in males and 11.59 +/- 3.38%/min in females, indicating a higher removal capacity in women. In the same subjects, the corresponding k2 values for Lipofundin S 10% (containing only long chain triglycerides) were higher, reflecting an elimination rate that is faster due to the use of soya bean phospholipids as emulsifier. In comparison, k2 values based on the course of the triglyceride concentrations are generally lower.     

Fat elimination in acute renal failure

Lipid metabolism and elimination of parenterally administered fat were investigated in 15 patients with acute renal failure (ARF). The mean triglyceride level was elevated to 2.56 +/- 1.43 mmol/l and the mean cholesterol level was 3.32 +/- 0.66 mmol/l, which is slightly below the normal range. A type IV hyperlipoproteinaemia was present in 47 per cent of the patients. The triglyceride content of LDL and VLDL was elevated and the cholesterol concentration of HDL and of LDL was reduced markedly. The fractional removal rate of triglycerides (K2) evaluated by an intravenous fat tolerance test using a bolus technique was reduced to 2.44 +/- 1.56 per cent/min which is about half of normal and correspondingly the elimination half life was prolonged to 28.4 min. No correlation could be demonstrated between the impairment of fat elimination and residual renal function, basal and VLDL triglyceride concentration or HDL cholesterol content.     

Triacetin: a potential parenteral nutrient

Triacetin, the water-soluble triglyceride of acetate, was infused in mongrel dogs at isocaloric (N = 6) or hypercaloric (approximately 1.5 REE, N = 7) rates in mongrel dogs for 3 hr. Ketone body and glucose production rates were quantified with [13C2] acetoacetate and [3H]glucose, respectively. Four additional animals were infused with glycerol to serve as controls for the hypercaloric triacetin infusion. Energy expenditure was determined in the isocaloric experiments. Results: no evidence of acute toxicity was observed during triacetin infusion at either rate. Plasma acetate concentrations increased from basal levels to approximately 1 and approximately 13 mmol/liter in the isocaloric and hypercaloric experiments, respectively. Plasma lactate and pyruvate concentrations decreased dramatically after 30 min of both isocaloric and hypercaloric triacetin infusions. Glucose production rates did not increase in either group, but glucose clearance decreased significantly in both groups (p less than 0.05) over the last hour of triacetin infusion. Plasma ketone body concentrations increased from 1.4 to 3.5 and 1.8 to 13.5 mumol/kg.min, respectively, during isocaloric and hypercaloric triacetin infusion. Resting energy expenditure increased from 3.0 +/- 0.3 to 4.0 +/- 0.5 kcal/kg.hr during isocaloric triacetin infusion (p less than 0.05). These studies indicate that triacetin can be administered to dogs at high rates without overt toxicity. The decrease in glucose clearance may represent competition between carbohydrate (glucose) and lipid (acetate). Triacetin infusion resulted in significant increases in ketone body production and concentration. These preliminary data indicate that triacetin may have a future role as a parenteral nutrient, and that further studies of its use are warranted.     

Glucose and insulin infusion directly after cardiac surgery: effects on systemic glucose uptake, catecholamine excretion, O2 consumption, and CO2 production

Systemic glucose uptake was studied in 31 patients during 4 hr starting 1 hr after open heart surgery, using the hyperinsulinemic "clamp" technique at different plasma insulin levels and at a glucose concentration of 6 or 10 mmol/liter. Possible metabolic side effects related to the glucose uptake were studied by measurements of urinary catecholamine excretion, O2 consumption, CO2 production, and arterial PCO2. A peak systemic glucose uptake of 7.0 +/- 0.4 mg/kg body weight/min was found at a plasma insulin concentration of 3192 +/- 150 mU/liter and a blood glucose concentration of 10.2 +/- 0.1 mmol/liter. No significant difference was found in urinary catecholamine excretion compared to control patients. O2 consumption was unaltered while a 15% increase in CO2 production was observed.     

Boys from populations with high-carbohydrate intake have higher fasting triglyceride levels than boys from populations with high-fat intake

Experimentally, high-carbohydrate diets have been shown to elevate triglycerides, but it has not been established whether this rise is permanent or transient. The authors approached this question by studying 719 boys from worldwide populations with marked differences in long-term carbohydrate intake. Fasting serum triglycerides, total cholesterol and high density lipoprotein (HDL) cholesterol concentrations were measured in boys aged 8 and 9 years from 12 countries--eight in Europe, three in Africa, and one in Asia. A standardized protocol was used for obtaining fasting blood and for the preparation, storage and transport of serum, and all measurements were made in one laboratory. Published values were used for the United States. Mean values for lipid levels per country were compared with the percentage of daily energy intake consumed as carbohydrate or fat, as determined by survey. Boys from populations with higher carbohydrate and lower fat intake had lower low density lipoprotein (LDL) cholesterol levels (univariate regression coefficient (+/- standard error, -0.028 +/- 0.009 mmol/liter for each percent of energy from carbohydrate; p less than 0.01, n = 13), but they also had higher fasting triglycerides (0.010 +/- 0.002 mmol/liter for each percent of energy from carbohydrate; p less than 0.01, n = 13) and lower HDL cholesterol levels (-0.022 +/- 0.003 mmol/liter for each percent of energy from carbohydrate; p less than 0.001, n = 13). These trends agree with results from epidemiologic studies within populations and from controlled dietary trials, and suggest that in normolipidemic healthy subjects, high-carbohydrate, low-fat diets cause higher triglyceride levels than diets that are higher in fats and oils.     

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.     

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.     

Parenteral infusion of long- and medium-chain triglycerides and reticuloendothelial system function in man

Previous study demonstrated that patients who received total parenteral nutrition (TPN) with standard intermittent infusion of long chain triglyceride (LCT) at 0.13 g kg-1hr-1 over 10 hr for each of three days showed a significant decline in 99Tc-sulfur colloid (TSC) clearance rate by the reticuloendothelial system (RES). The present studies evaluated eight patients who received the same total lipid dose of LCT infused continuously as in a three-in-one admixture, and another nine patients receiving the same amount of fat as a medium chain triglyceride (MCT)/LCT (75%/25%) emulsion intermittently over 10 hr at 0.13 g kg-1hr-1 for three consecutive days. Patients were given continuous total parenteral nutrition (TPN) comprised of protein, 1.5 g kg-1day-1, and dextrose, 4.5 g kg-1day-1. RES function was examined by measuring the clearance rates of intravenously injected TSC while receiving TPN containing only protein and dextrose, and again after three days of fat infusion. Mean (+/- SEM) clearance rate constants before and after continuous LCT infusion were 0.38 +/- 0.09 and 0.41 +/- 0.08 min-1, respectively, while those before and after intermittent MCT/LCT infusion were 0.50 +/- 0.18 and 0.73 +/- 0.24 min-1, respectively. In contrast to intermittent LCT infusion, the administration of continuous LCT or an intermittent MCT/LCT mixture does not impair TSC clearance by the RES. These findings suggest that condensing the daily period of LCT infusion at standard dosage may exceed the rate of metabolic utilization, resulting in increased fat removal and diminished TSC uptake by the RES.(ABSTRACT TRUNCATED AT 250 WORDS)     

Elimination of lipofundin S during the intravenous fat tolerance test in patients with low, medium, and high fasting triglyceride concentrations

The intravenous fat tolerance test with Lipofundin S (0.5 ml of 20% emulsion/kg body weight) was performed in 22 male nondiabetic patients. According to their fasting triglycerides (TG), the patients were arranged into three groups: low (less than 2.8 mmol/liter), medium (2.8-5.7 mmol/liter), and high (greater than 5.7 mmol/liter) concentrations. Fractional elimination rates of injected Lipofundin S decreased from 11.08 in low TG to 4.57%/min in high TG; they were positively correlated with fasting levels of high-density lipoprotein cholesterol but negatively with those of TG. The same pattern of correlations was observed with fractional catabolic rates of endogenous TG as measured after injection of tritium-labeled glycerol. The intravenous Lipofundin S load effected transient TG and free fatty acid elevations which were delayed in high TG. The elimination mechanisms of injected Lipofundin S and of endogenous TG are compared.     

Pharmacokinetics of ampicillin during parenteral nutrition

Seven healthy volunteers (four males, 20-28 years) were studied to determine the effect of parenteral nutrition (PN) on ampicillin clearance. Each volunteer received intravenous infusions of 1 liter of PN (3.75% amino acid and 10% dextrose) alternating with 1 liter of 10% dextrose (containing all additives as PN except for calcium and phosphorus); and a meal containing similar fluid volume, caloric, protein, and sodium content as the PN solution. Ampicillin (250 mg) was given intravenously 2 hr after commencement of each intravenous solution and 4 hr after the meal. During PN infusion, the mean (+/- SE) glomerular filtration rate (GFR) as indicated by creatinine clearance was 125 +/- 18 ml/min; ampicillin pharmacokinetic data included area under the serum ampicillin concentration-time curve of 899 +/- 118 micrograms min/ml, terminal elimination half life of 37 +/- 4.3 min, volume of distribution at steady state of 11.9 +/- 1.6 liter, total body clearance of 4.7 +/- 0.6 ml/min/kg, renal clearance of 3.8 +/- 0.5 ml/min/kg, and 82 +/- 6.7% of the ampicillin administered was excreted in urine over 10 hr. The results were not significantly altered by different nutrient regimens or the order of infusion of intravenous solutions. We conclude that the use of PN is unlikely to affect the pharmacokinetics of ampicillin provided the renal functions including GFR, remain unchanged.     

Physiologic growth hormone replacement improves fasting lipid kinetics in patients with HIV lipodystrophy syndrome

BACKGROUND: HIV lipodystrophy syndrome (HLS) is characterized by accelerated lipolysis, inadequate fat oxidation, increased hepatic reesterification, and a high frequency of growth hormone deficiency (GHD). The effect of growth hormone (GH) replacement on these lipid kinetic abnormalities is unknown. OBJECTIVE: We aimed to measure the effects of physiologic GH replacement on lipid kinetics in men with HLS and GHD. DESIGN: Seven men with HLS and GHD were studied with the use of infusions of [13C1]palmitate, [2H5]glycerol, and [2H3]leucine to quantify total and net lipolysis, palmitate and free fatty acid (FFA) oxidation, and VLDL apolipoprotein B-100 synthesis before and after 6 mo of GH replacement (maximum: 5 microg x kg(-1) x d(-1)). RESULTS: GH replacement decreased the rates of total lipolysis [FFA(total) rate of appearance (x +/- SE): from 4.80 +/- 1.24 to 3.32 +/- 0.76 mmol FFA x kg fat(-1) x h(-1); P < 0.05] and net lipolysis (FFA(net) rate of appearance: from 1.87 +/- 0.34 to 1.20 +/- 0.25 mmol FFA x kg fat(-1) x h(-1); P < 0.05). Fat oxidation decreased (from 0.28 +/- 0.02 to 0.20 +/- 0.02 mmol FFA x kg lean body mass(-1) x h(-1); P < 0.002), as did the rate of appearance of FFAs available for intrahepatic reesterification (from 0.50 +/- 0.13 to 0.29 +/- 0.09 mmol FFA x kg fat(-1) x h(-1); P < 0.03). Fractional and absolute synthetic rates of VLDL apolipoprotein B-100 were unaltered. These kinetic changes were associated with a decrease in the waist-to-hip ratio but no significant change in fasting plasma lipid concentrations. Fasting plasma glucose concentrations increased after treatment (from 5.2 +/- 0.2 to 5.8 +/- 0.3 mmol/L; P < 0.01). CONCLUSIONS: Physiologic GH replacement has salutary effects on abnormal lipid kinetics in HLS. The effects are mediated by diminished lipolysis and hepatic reesterification rather than by increased fat oxidation.     

Effects of short-chain fructo-oligosaccharides on glucose and lipid metabolism in mild hypercholesterolaemic individuals

BACKGROUND: The intake of 10 g/day of short-chain-fructo-oligosaccharides (sc-FOS) has been shown to increase significantly bifidus counts and to produce high amounts of short-chain fatty acids (SCFA), presumed to influence glucose and lipid metabolism. AIM: To evaluate the effects of moderate intake of sc-FOS on glucose and lipid metabolism in individuals with mild hypercholesterolaemia. Design: A randomized double-blind sequential cross-over study. SUBJECTS AND METHODS: Thirty subjects of both genders (20 M/10 F), mean age 45.5+/-9.9 years (M+/-SD), BMI 26.6+/-2.2 kg/m(2), with plasma cholesterol >5.17 and <7.76 mmol/l and plasma triglycerides <3.45 mmol/l, participated in the study. The study was performed after a wash-out period of 1 month and a run-in period of 1 month to stabilize patients on a standard diet (CHO 50%, fat 30%, protein 20%, fibre 20 g/day) plus placebo (maltodextrine plus aspartame 15 g/day). At the end of run-in, subjects were randomly assigned to receive sc-FOS (Actilight) (10.6g/day) or placebo (maltodextrine plus aspartame 15 g/day) with tea and/or coffee for a duration of 2 months and thereafter switched to the other treatment for additional 2 months. Plasma glucose, total and lipoprotein (VLDL, LDL, HDL) cholesterol and triglyceride concentrations were measured in the fasting state at the end of run-in and of each treatment period. At the end of the two treatment periods, patients consumed a standard test meal (protein 15%, carbohydrate 34%, fat 51%, kJ 3988) 1h after the administration of 5.3g of sc-FOS or placebo; plasma glucose, insulin, free fatty acid (FFA) and triglyceride responses to the test meal were evaluated. RESULTS: No significant difference in fasting parameters was detected between the two treatments. After sc-FOS and placebo plasma cholesterol levels were, respectively, 6.47+/-0.70 and 6.44+/-0.78 mmol/l (n.s.) and plasma triglycerides were 1.53+/-0.71 and 1.56+/-0.53 mmol/l (n.s.). No significant differences were observed in cholesterol and triglyceride content of VLDL, LDL and HDL and in plasma Apo A1 levels; conversely, fasting plasma Lp(a) concentrations were significantly increased after sc-FOS (37+/-38 vs. 33+/-35 mg/dl; P<0.005). Postprandial responses of glucose, FFA and triglycerides were not significantly different between sc-FOS and placebo, while postprandial insulin response (incremental area) was significantly reduced after sc-FOS compared to placebo (14,490+/-7416 vs. 17,760+/-7710 pmol/l x 300 min; P<0.02). CONCLUSIONS: A moderate intake of sc-FOS has no major effects on lipid metabolism, both in the fasting and in the postprandial period, in individuals with mild hypercholesterolaemia. A small but significant increase of Lp(a) concentrations was observed with sc-FOS consumption together with a reduction of the postprandial insulin response; however, the clinical relevance of these small effects is unclear.     

Thermogenesis from intravenous medium-chain triglycerides

Eighteen hospitalized patients dependent on total parenteral nutrition (TPN) were randomly enrolled into a prospective study comparing intravenous long-chain triglycerides (LCT) with a physical mixture of 75% medium-chain triglycerides (MCT) and 25% LCT. The TPN was given continuously as amino acids and glucose over 5 days with the respective lipid emulsion given intermittently during each day for 10 hr. Indirect calorimetry was measured on each patient before the lipid emulsion was administered in the morning and again 10 hr later near the end of the lipid infusion, on days 1, 3, and 5. Resting energy expenditure, VO2, VCO2, and calculated fat oxidation were shown to increase during MCT infusion but not during LCT administration, (resting energy expenditure 899 +/- 37 to 1085 +/- 40, compared with 978 +/- 23 to 976 +/- 39, kcal/m2 body surface area [BSA]/day, respectively, p less than 0.0002; VO2: 129.9 +/- 5.2 to 157.2 +/- 5.9, compared with 140.9 +/- 3.6 to 141.2 +/- 5.9 ml O2/min/m2 BSA, respectively, p less than 0.0005; and VCO2: 110.7 +/- 4.4 to 127.5 +/- 4.3, compared with 118.3 +/- 2.8 to 118.0 +/- 5.3, ml CO2/min/m2 BSA, respectively, p less than 0.0076; calculated fat oxidation 10.7 +/- 1.5 to 19.3 +/- 2.4, compared with 20.0 +/- 2.7 to 20.0 +/- 3.6, kcal/m2 BSA/hr, respectively, p less than 0.014). Respiratory quotient tended to fall with lipid infusion but did not change statistically. Body temperatures were unaltered by either fat infusion. It is concluded that TPN consisting of MCT causes an increased thermogenesis, most likely through increased fat oxidation, reflective of MCT's property as an obligate fuel. The increased thermogenesis occurs without an increase in body temperature.     

Splanchnic glucose balance and insulin resistance in the early postoperative phase of cardiac surgery

The splanchnic balance of glucose was studied in the basal state and at three levels of "clamped" hyperinsulinemia (260 +/- 23, 510 +/- 59, 3875 +/- 367 mU/liter) in 24 patients (43-70 years of age), who had undergone coronary surgery about 1 hr previously. The splanchnic balance of glucose in the basal state was negative in all patients (-1.6 +/- 0.3 mg/kg/min) and was changed into a zero-balance within 30 min when 0.15 or 0.3 U/kg/hr of insulin was infused. At an insulin infusion rate of 1.0 U/kg/hr the net splanchnic glucose balance was turned into a significant positive balance of an average 0.9 +/- 0.3 mg/kg/min.     

Towards optimizing the timing of the pre-exercise meal

The purpose of this study was to compare the effect a 6-hr versus 3-hr prefeeding regimen on exercise performance. The subjects were 8 active women (21.4 +/- 0.9 years, 60.4 +/- 2.4 kg, 19.9 +/- 1.3% body fat, and 165.6 +/- 2.1 cm). All women completed 2 exercise trials (separated by 3-6 d) on a treadmill where they ran at moderate intensity for 30 min with 30-s sprints at 5-min intervals, followed directly by increasing incrementally the grade until volitional fatigue was achieved. The exercise trials were performed 3 hr and 6 hr after consuming 40 +/- 3 kJ/kg meal. Time to exhaustion was 0.75 min shorter (p =.0001) for the 6-H trials compared to the 3-H trials. There were no significant differences in submaximal or peak oxygen uptake, heart rate, or rating of perceived exertion (p >.05). The 6-H trials compared to the 3-H trials resulted in.05 lower RERs (p =.0002), and a 2 mmol lower blood lactate at exhaustion (p =.012). Blood glucose levels and cortisol responses to exercise were similar between trials (p >.05). However, both resting and post exercise insulin levels were lower during 6-H trials. It was concluded that performance of moderate- to high-intensity exercise lasting 35-40 min is improved by consuming a moderately-high carbohydrate, low fat, low protein meal 3-hr before exercise compared to a similar meal consumed 6 hr prior to exercise. Thus, athletes should not skip meals before competition or training sessions.