Soybean oil emulsion administration during parenteral nutrition in the preterm infant: effect on essential fatty acid, lipid, and glucose metabolism

To examine the effect of a soybean oil emulsion on essential fatty acid, lipid, and glucose metabolism, preterm infants were randomized to receive 0.5 g/kg/d lipid for 5 days (n = 10, group 1) or 0.5 increased to 2.0 g/kg/d over 5 days (n = 11, group 2). Triene/tetraene ratios did not change in group 1, but decreased in group 2. In both groups, plasma phospholipid linoleate (percent and micrograms per milliliter) increased, the increase being greater in group 2. In both groups, percent content of arachidonate and 5,8,11-eicosatrienoate decreased, and that of oleate remained unchanged. In contrast, absolute content of arachidonate and oleate tended to increase, and that of 5,8,11-eicosatrienoate remained unchanged. At a lipid intake of 0.5 g/kg/d, no infants had hyperlipemia. When lipid intake exceeded 1.0 g/kg/d, the frequency of hypertriglyceridemia (triglycerides greater than 200 mg/dL) and free fatty acidemia, with the free fatty acid/molar albumin ratio exceeding 6:1, increased. Plasma glycerol increased slightly, but was substantially less than the rise in enzymatically determined triglycerides. Hyperglycemia was self-limiting and did not require alteration in dextrose intake. Thus, (1) infusion of a soybean oil emulsion at 0.5 to 2.0 g/kg/d maintains essential fatty acid status and phospholipid arachidonate concentrations; (2) significant hyperlipemia occurs when lipid intake exceeds 1.0 g/kg/d; (3) hyperglycemia associated with lipid infusion tends to be self-limiting and may not require alteration in lipid or dextrose intake; and (4) enzymatically determined triglycerides may be used to monitor lipid tolerance, provided that allowance is made for a small but systematic overestimation resulting from the rise in plasma glycerol.     

Safflower oil emulsion administration during parenteral nutrition in the preterm infant. 1. Effect on essential fatty acid status

To determine the effect of a safflower oil emulsion on the essential fatty acid (EFA) status of preterm infants during parenteral nutrition, subjects were randomized to receive Liposyn at 0.34 g (group 1), 0.68 g (less than 0.5% of lipid from linolenic acid, group 2), or Modified Liposyn at 0.68 g/kg/day (5.0% of lipid from linolenic acid, group 3). Doses of 0.34 and 0.68 g of Liposyn provided linoleic acid in amounts equivalent to 2 and 4% of the estimated caloric requirement (120 cal/kg/day) and 5 and 10% of the actual caloric intake. No significant differences were detected in plasma phospholipid triene/tetraene ratios and arachidonic acid levels between groups 1 and 2 or between groups 2 and 3, respectively. Plasma phospholipid triene/tetraene ratio and arachidonic acid did not change in the lipid-supplemented group throughout the study period, but the former remained significantly lower (p less than 0.001) and the latter significantly greater (p less than 0.001) than in a reference group of infants who received fat-free parenteral nutrition. We conclude that Liposyn administration providing linoleic acid at 2 or 4% of the estimated caloric requirement or 5 or 10% of the actual caloric intake prevented any significant changes in essential fatty acid status from occurring. Moreover, linolenic acid supplementation at 5% of the total lipid intake did not appear to affect arachidonic acid synthesis in the preterm infant.     

The effect of three intravenous fat emulsions containing different concentrations of linoleic and alpha-linolenic acids on the plasma total fatty acid profile of neonates.

We determined the fatty acid profile of total plasma lipids in infants who received one of three intravenous fat emulsions that differed primarily in their linoleic and alpha-linolenic acid content: (I) a safflower oil emulsion, (II) a 50:50 mixture of safflower and soybean oils, or (III) a soybean oil emulsion. After 2 weeks of fat therapy, oleic acid, expressed as a percentage of total plasma lipid fatty acids, decreased in all groups, but less so in group III (p less than 0.01). The linoleic acid percentage increased in all groups, but group I had the greatest increase (p less than 0.05). Group II patients had higher percentages of the linoleic acid metabolites, dihomo-gamma-linolenic acid (II greater than I, p less than 0.05; II greater than III, p less than 0.01) and arachidonic acid (II greater than III, p less than 0.05). Group II patients also had higher levels of alpha-linolenic acid (II greater than I, p less than 0.05) and its metabolite, eicosapentaenoic acid (II greater than I, p less than 0.05). Another alpha-linolenic acid metabolite, docosahexaenoic acid, however, increased in group III, remained stable in group II, and decreased in group I (III and II greater than I, p less than 0.05). We conclude that the content of linoleic acid and alpha-linolenic acid in intravenous fat emulsions results in statistically significant changes in the fatty acid profile of total plasma lipids in infants receiving total parenteral nutrition.     

Total parenteral nutrition with intralipid in premature infants receiving TPN with heparin: effect on plasma lipolytic enzymes, lipids, and glucose

Plasma lipolytic activity (lipoprotein lipase and hepatic lipase), free fatty acids (FFA), triglycerides, cholesterol, and glucose levels were measured in 21 premature infants [gestational age 26-37 weeks (mean +/- SEM 30.4 +/- 0.63 weeks), aged 1-8 days (mean +/- SEM 3.00 +/- 0.35 days)]. All infants were maintained on total parenteral nutrition with heparin (1 U/ml) and were given Intralipid, 1, 2, and 3 g/kg/day, over 15 h on days 1, 2, and 3, respectively. Blood samples were drawn before and at the end of Intralipid administration. Baseline plasma lipolytic activity, before the start of lipid infusion, was 1.54 +/- 0.24 U/ml (1 U = 1 mumol [3H]oleic acid released from tri[3H]olein/h). Lipolytic activity increased after lipid infusion to 4.04 +/- 0.96, 4.32 +/- 0.63, and 6.09 +/- 1.00 U/ml on days 1, 2, and 3 of the study. Hepatic lipase amounted to 38-47% of total lipolytic activity. During the 3 days of lipid infusion, there were dose-dependent increases in plasma FFA, triglyceride, and cholesterol. Whereas FFA and triglyceride concentrations returned to prelipid infusion levels 9 h after stopping the infusion of Intralipid, 1, 2, or 3 g/kg, there was a cumulative increase in plasma cholesterol and glucose concentrations. The close correlation between FFA concentrations and plasma lipolytic activity (r = 0.655, p less than 0.001) suggests considerable intravascular lipolysis. The positive correlation between plasma FFA and triglycerides (r = 0.632, p less than 0.001) and FFA and cholesterol (r = 0.582, p less than 0.001) indicate, however, that intravascular lipolysis does not prevent the lipemia associated with Intralipid infusion to low birth weight infants.(ABSTRACT TRUNCATED AT 250 WORDS)     

Triglycerides, free fatty acids, free fatty acids/albumin molar ratio, and cholesterol levels in serum of neonates receiving long-term lipid infusions: controlled trial of continuous and intermittent regimens

We compared intermittent (8 hours/day) versus continuous (24 hours/day) isocaloric lipid infusion regimens in 28 neonates. The lipid dose was increased incrementally by 0.5 gm/kg/day to either 3 gm/kg/day or until fat contributed 40% of daily calories. Serum total triglycerides, free fatty acids, free fatty acids/albumin molar ratio, and total cholesterol levels were measured prior to the daily lipid infusion, at the end of the intermittent infusion, and at 8 hours during the continuous infusion. Neonates less than 32 weeks postconception had significant fluctuation of triglycerides, free fatty acids, and free fatty acids/albumin molar ratio during the intermittent regimen at all lipid doses, but not during the continuous regimen. Neonates greater than or equal to 32 weeks postconception had significant fluctuation of serum triglycerides, free fatty acids, and free fatty acids/albumin molar ratio during the intermittent regimen with a lipid dose greater than or equal to 2 gm/kg/day, but not during the continuous regimen at all lipid doses. Serum free fatty acids correlated closely with serum triglycerides during both regimens (r = 0.89, P less than 0.001). Serum total cholesterol rose with increasing lipid doses during both regimens (f = 8.16, P less than 0.05). We conclude that neonates less than 32 weeks postconception tolerate the continuous regimen better than the intermittent regimen at all lipid doses; neonates greater than or equal to 32 weeks postconception tolerate both regimens well at lipid dose less than 2 gm/kg/day, but tolerate a continuous regimen better with lipid dose greater than or equal to 2 gm/kg/day.     

The role of magnesium in neonatal calcium homeostasis: effects of magnesium infusion on calciotropic hormones and calcium

Magnesium (Mg) deficiency is a possible etiologic factor contributing to neonatal hypocalcemia. In adults, parathyroid hormone (PTH) secretion is negatively feedback regulated by acute changes in serum Mg concentration, but paradoxically Mg deficiency may lead to functional hypoparathyroidism and hypocalcemia. We hypothesized that in neonates, Mg administration will cause changes in PTH secretion and serum Ca concentration that will be inversely related to serum Mg status. We also hypothesized that Mg administration will result in increased calcitonin (CT) secretion. Thirty-nine newborn infants with birth weights greater than 1500 g were studied on day 3 of life. Ten received placebo, and 29 intravenous magnesium sulfate (MgSO4), 6 mg elemental Mg/kg body weight, over 1 h. Serum Mg, Ca, PTH, and CT were measured at time 0 (baseline, preinfusion) and 1, 2, 6, 12, 24, and 48 h postinfusion. In both groups combined, baseline PTH correlated with baseline Mg (r = 0.72, p less than 0.005), and with baseline Ca (r = 0.68, p less than 0.005). In the control group there was no change in serum Mg, Ca, PTH, and CT during the study period. In magnesium sulfate-infused infants: 1) serum Mg concentration rose from 1.80 +/- 0.06 to 2.82 +/- 0.07 mg/dl (mean +/- SEM, p less than 0.001); 2) the change from baseline in serum PTH at 1, 6, and 12 h postinfusion correlated inversely with baseline Mg (p less than 0.05); 3) the change from baseline in serum Ca at 1, 2, and 24 h postinfusion correlated inversely with baseline Mg (p less than 0.005); 4) serum CT remained unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)     

Glycerol metabolism and triglyceride-fatty acid cycling in the human newborn: effect of maternal diabetes and intrauterine growth retardation.

Kinetics of glycerol metabolism and triglyceride/fatty acid cycling were quantified in 12 healthy, normal, appropriate-for-gestational-age (AGA) infants, eight small-for-gestational-age (SGA) infants, and five infants of insulin-dependent diabetic mothers (IDM) at less than 48 h of age. Stable isotope-labeled [2-13C]glycerol and [6,6-2H2]glucose in combination with indirect respiratory calorimetry were used. The tracers were used as constant rate infusion and steady state isotopic enrichment of glucose, glycerol, and bicarbonate was measured by mass spectrometric methods. After a 7- to 9-h fast, the plasma glucose, glycerol, and FFA concentrations were similar in the AGA and IDM groups. In the SGA group, the plasma glucose concentration was significantly lower than that in the AGA group throughout the study, but plasma FFA and glycerol concentrations were not different from those in the AGA infants. Plasma betahydroxybutyrate concentration was significantly elevated in the AGA group compared with IDM and SGA infants (AGA 0.59 +/- 0.39, SGA 0.35 +/- 0.09, IDM 0.33 +/- 0.21 mmol/L; mean +/- SD). The rate of appearance of glycerol was significantly elevated (p less than 0.05) in SGA infants (AGA 9.47 +/- 2.11, IDM 9.55 +/- 2.14, SGA 12.15 +/- 3.87 mumol/kg.min). Between 80 and 90% of glycerol turnover was converted to glucose, accounting for 20% of glucose turnover with no significant difference in the three groups. Approximately 35% of glycerol carbon was recovered in the bicarbonate (CO2) pool. Less than 5% of CO2 carbon was derived from glycerol. Estimation of triglyceride-fatty acid cycle revealed that the triglyceride energy mobilized was increased in SGA infants.(ABSTRACT TRUNCATED AT 250 WORDS)     

Carnitine deficiency in premature infants receiving total parenteral nutrition: effect of L-carnitine supplementation

To investigate whether L-carnitine supplementation may correct nutritional carnitine deficiency and associated metabolic disturbances in premature infants receiving total parenteral nutrition, an intravenous fat tolerance test (1 gm/kg Intralipid over four hours) was performed in 29 premature infants 6 to 10 days of age (15 receiving carnitine supplement 10 mg/kg . day L-carnitine IV, and 14 receiving no supplement). Total carnitine plasma values were normal or slightly elevated in supplemented but decreased in nonsupplemented infants. In both groups, fat infusion resulted in an increase in plasma concentrations of triglycerides, free fatty acids, D-beta-hydroxybutyrate, and short-chain and long-chain acylcarnitine, but total carnitine values did not change. After fat infusion, the free fatty acids/D-beta-hydroxybutyrate ratios were lower and the increase of acylcarnitine greater in supplemented infants of 29 to 33 weeks' gestation than in nonsupplemented infants of the same gestational age. This study provides evidence that premature infants of less than 34 weeks' gestation requiring total parenteral nutrition develop nutritional carnitine deficiency with impaired fatty acid oxidation and ketogenesis. Carnitine supplementation improves this metabolic disturbance.     

Medium-chain triglycerides in infant formulas and their relation to plasma ketone body concentrations

A mild ketosis is known to prevail in the mother, fetus, and newborn infant during the 3rd trimester and in the early neonatal period. It has been shown that during an equivalent period in the rat ketone bodies are readily oxidized and serve as key substrates for lipogenesis in brain. Since medium-chain triglycerides are known to be ketogenic, preterm infants may benefit from dietary medium-chain triglycerides beyond the point of enhanced fat absorption. Our objective was to determine the ketogenic response in preterm infants (gestational age: 33 +/- 0.8 wk) fed three different isocaloric formulas by measuring the concentrations of 3-hydroxybutyrate and acetoacetate in the plasma of these infants. At the time of entrance to the study the infants were receiving 110 kcal/kg/24 h. Study I (11 infants): the infants were fed sequentially in the order; PM 60/40 (PM), Special Care Formula (SCF), and Similac 20 (SIM). In SCF greater than 50% of the fat consists of medium-chain length fatty acids while PM and SIM contain about 25%. The concentration of 3-hydroxybutyrate in plasma was significantly higher when infants were fed SCF than PM and SIM [0.14 +/- 0.03, 0.06 +/- 0.01, and 0.05 +/- 0.01 mM, respectively (p less than 0.01)]. Study II (12 infants); the infants were fed SCF, then SIM, or the reverse. The concentration of acetoacetate in plasma was 0.05 +/- 0.01 and 0.03 +/- 0.01 mM when infants were fed SCF and SIM, respectively (0.1 greater than p greater than 0.05). The concentrations of 3-hydroxybutyrate in plasma were similar to those measured in study I for the respective formulas.(ABSTRACT TRUNCATED AT 250 WORDS)     

Postheparin lipolytic activity and Intralipid clearance in very low-birth-weight infants

The effect of heparin (10 U/kg) on serum lipolytic activity, triglyceride and FFA levels, during four hours infusion of 0.5 gm/kg Intralipid was measured in 18 AGA infants, 25 to 32 weeks' gestational age. PHLA, TG, and FFA were measured at 0, 10, 30, 120, and 240 minutes of infusion of Intralipid, before and following a bolus of 10 U/kg heparin iv. Lipolytic activity, measured by hydrolysis of activated tri-3H-oleate and expressed in mumol FFA released per milliliter serum per hour, was not detected in serum before heparin administration. Ten minutes after heparin administration peak PHLA was significantly higher in infants of 27 to 32 weeks' gestation than in infants of 25 to 26 weeks' gestation. There was no significant difference in peak PHLA between infants of 27 to 28 and 29 to 32 weeks' gestation. PHLA returned to baseline (zero) two hours after heparin administration in all infants. Infants of 25 to 26 weeks' gestational age had significantly higher concentrations of serum triglycerides before and during Intralipid infusion than in infants of 27 to 32 weeks' gestational age. Although there was a transient rise in FFA 10 and 30 minutes after heparin administration, the levels of FFA and triglycerides were not different at the end of infusion with or without heparin in either group, suggesting that a single bolus of heparin has only a transient effect on Intralipid clearance.     

Enhanced lipid utilization in infants receiving oral L-carnitine during long-term parenteral nutrition

Fourteen infants requiring long-term total parenteral nutrition but able to tolerate small quantities of enteral feedings were randomized into carnitine treatment and placebo control groups. All infants had received nutritional support devoid of carnitine. Plasma carnitine levels and observed plasma lipid indices were not different before supplementation. Under standardized, steady-state conditions, 0.5 g/kg fat emulsion (intralipid) was administered intravenously over 2 hours both before and after infants received 7 days of continuous nasogastric or gastric tube L-carnitine (50 mumol/kg/day) or placebo. Plasma triglyceride, free fatty acid, acetoacetate, beta-hydroxybutyrate, and carnitine concentrations were observed at 0 (start of lipid infusion), 2, and 4 hours for pre- and post-treatment periods, and in addition at 6 and 8 hours after carnitine supplementation. Infants receiving carnitine had significantly greater beta-hydroxybutyrate plasma concentrations (P less than 0.05) and carnitine (P less than 0.001) at 0, 2, 4, 6, and 8 hours, and greater plasma acetoacetate concentrations (P less than 0.05) at 2, 4, 6, and 8 hours, compared with controls. Twenty-four-hour urinary carnitine excretion was very low for both groups before supplementation; after supplementation, excretion was higher (P less than 0.05) in the carnitine group. No significant differences were found between groups for plasma triglyceride or free fatty acid concentrations at any observation period. This study demonstrated enhanced fatty acid oxidation, as evidenced by increased ketogenesis, with L-carnitine supplementation in infants receiving long-term total parenteral nutrition.     

Body composition and cold resistance of the neonatal pig from European (Large White) and Chinese (Meishan) breeds

Body composition, plasma parameters and cold resistance were compared in neonatal pigs from Chinese (Meishan, Ms) and European (Large White, Lw) breeds. Newborn Ms pigs weighed less but had a higher (p less than 0.05) percentage of body dry matter and protein than the Lw pigs, whereas both breeds had similar levels of body fat and liver and muscle glycogen. Plasma concentrations of fructose and alpha-fetoprotein were lower (p less than 0.05) in the newborn Ms pigs. Cold resistance test performed in a 6-7 degrees C environment on the same piglets when aged 2 and 24 h, showed that in both breeds, cold resistance was closely dependent upon body weight and significantly improved (p less than 0.01) with age. Despite their 16% lower body weight, Ms piglets were, at both ages studied, as resistant to cold as the Lw ones. Breed had no effect on pretest concentration of plasma glucose and noradrenaline, but pretest concentrations of plasma free fatty acids (FFA) were higher (p less than 0.01) in the Ms than in Lw piglets and those of adrenaline were lower (p less than 0.01) in the Ms Lw piglets and those of adrenaline were lower (p less than 0.01) in the Ms piglets. Breed had no significant effect on the response of plasma glucose, FFA and catecholamines during exposure to cold. At both ages of exposure, plasma concentrations of glucose and catecholamines were significantly increased. Plasma concentrations of FFA were increased (p less than 0.01) at 2 h, but at 24 h a decrease (p less than 0.01) was observed during cold exposure. Colostrum from Ms sows had greater concentration of lipids than that from Lw sows. It is suggested that the similar resistance to cold of the Ms and Lw piglets despite the lower body weight of the former is due, in part, to a greater availability of FFA as an energy source.     

Effect of hydrocortisone on intravenous glucose tolerance in small-for-gestational-age infants

The effects of hydrocortisone (H) hemisuccinate (10 mg/kg) on intravenous glucose tolerance (1 g/kg) was studied in eight full term small-for-gestational-age (SGA) infants and compared to seven control infants at mean age of 41 h. After H, the rate of glucose disappearance was (mean +/- SD) 0.92 +/- 0.27 vs 1.24 +/- 0.31% min in controls (p less than 0.01). Glucose space was similar after H: 449 +/- 62 ml/kg and in the control group 468 +/- 75 ml/kg. At 5 and 15 min, although higher in the H group, mean plasma glucose was not significantly different. The difference became significant at 30 min (t = 2.00; p = 0.05), 45 (t = 2.298; p less than 0.05) and 60 min (t = 2.48; p less than 0.02). Plasma insulin concentration did not change after glucose injection in the control group. After H administration, plasma insulin increased: the basal median value was less than 5 mU/ml (range less than 5-18) and at 60 min it rose to 30 mU/ml (range 7.5-89). These data suggest that in newborn infants corticoids induce a reduced peripheral uptake of glucose independent of insulin secretion.     

EFFECTS OF INJECTED LIPID EMULSION ON OXYGEN CONSUMPTION, RQ, TRIGLYCERIDE, FREE-FATTY-ACID AND β-HYDROXYBUTYRATE LEVELS IN SMALL-FOR-GESTATIONAL-AGE (SGA) INFANTS

ABSTRACT. Ten SGA infants were studied from 4 hours after birth (day 1) and again at 28 hours (day 2) before and for 4 hours after single injections of 0.5 g of Intralipid® fat/kg b. w. (IL-group). Eight other SGA infants were given 9–10 ml/kg of breast milk (BM-group). After lipid injection the elimination of triglycerides (TG) from plasma was markedly delayed. On day 2 lipolysis had improved, but was still slower than in previously studied AGA infants. The initial FFA plasma level was higher on day 1 than on day 2. Oxidation of released fatty acids was confirmed by a significant increase of V_o, and a decrease of RQ on day 1 and 2. In all infants the β-hydroxybutyrate level in plasma increased and was still elevated 4 hours after injection of fat. A negative correlation was found between β-hydroxybutyrate levels and RQ. In the BM-group changes in TG and β-hydroxybutyrate levels were small and insignificant. FFA had decreased 60 min after breast milk on day 1. In conclusion: TG elimination from plasma was impaired on day 1 and had slightly improved on day 2. The fatty acids released by lipolysis were oxidized as seen by increasing V_o, falling RQ and increasing β-hydroxybutyrate plasma levels both on day 1 and day 2.     

Essential fatty acid status of the premature infant during short-term fat-free parenteral nutrition

This study was designed to evaluate the effect of fat-free parenteral nutrition on the essential fatty acid status of a group of stable premature infants during the first 10 days of life. Nine infants had a gestational age of less than 32 weeks (Group 1), and 10 infants, 32-34 weeks (Group 2). Five of nine infants in Group 1 and two of 10 infants in Group 2 developed essential fatty acid deficiency (EFAD) (triene/tetraene ratio greater than 0.4). In three infants, EFAD was present by 5 days of age; and in four, between 5 and 10 days of age. The difference in frequency of EFAD between Groups 1 and 2 is statistically significant (p less than 0.05). The development of EFAD as a function of postnatal age could be predicted using a simple regression, y = -0.14 + 0.07x (r = 0.64, p less than 0.0001), where y represents the triene/tetraene ratio and x the postnatal age in days. We conclude that (a) EFAD may develop rapidly in the premature infant; (b) the more immature the infant, the greater the risk of EFAD; (c) the degree of EFAD increases with the duration of fat-free parenteral nutrition.     

Effect of parenteral fat emulsion on the pulmonary and reticuloendothelial systems in the newborn infant.

Analysis of phospholipids (PL), cholesterol esters, triglycerides (TG), and free fatty acids (FFA) was performed on plasma and RBCs in two sick low-birth-weight infants who received total parenteral nutrition including Intralipid for the first 9 and 12 weeks of life, respectively. There was an increase in the total concentration of the plasma IG and FFA in the infants receiving Intralipid as compared with controls. These elevated lipid levels were not detected by visual inspection of the plasma. When compared with control infants, higher levels of linoleic acid were found in the plasma and RBCs of infants receiving Intralipid while plasma PL contained less arachidonate. Histological examination of the lung in both infants who received Intralipid revealed numerous globules of sudanophilic material in alveolar macrophages and capillaries. There is a possibility that prolonged administration of Intralipid may be associated with altered pulmonary and reticuloendothelial system function.     

Small intestinal mucosal fatty acid uptake and esterification in infants and children.

Oleic acid uptake and esterification in intact intestinal mucosa were studied in 14 infants and children with chronic non-specific diarrhea, but histologically normal small intestinal mucosal biopsies, using an in vitro technique. The uptake rate was 5.876 +/- 1.942 nmol fatty acid/mg Nigrogen/minute and the esterification rate was 4.060 +/- 1.010 nmol fatty acid/mg Nitrogen/minute, comparable to previous adult esterification studies. No effect of age on either esterification or uptake was present. Mucosal injury resulted in significant reductions in esterification (p less than 0.001) and uptake (p less than 0.05) compared to controls. Bile acid deficiencies led to reductions in mucosal esterification (p less than 0.05) but not uptake.     

Fat intake and metabolism in Swedish and Italian infants

The purpose of the study was to compare fat intake and metabolism between two infant populations from Sweden and Italy given breast milk or similar infant formulas, but different weaning foods. Nutrient intake and fat metabolism were studied prospectively from 3-12 mo in 68 Swedish and 46 Italian healthy infants, breastfed or given similar infant formulas in combination with Swedish or Mediterranean weaning foods. Although nutrient intake and fat metabolism were similar at 6 mo, fat intake was lower at 12 mo in the Italian than in the Swedish formula group (p < 0.001). At 6 and 12 mo, higher dietary ratios of monounsaturated to saturated fatty acids (p < 0.01 and p < 0.001, respectively), and monounsaturated to polyunsaturated fatty acids (p < 0.05, p < 0.001) were found in the Italian than in the Swedish formula group. Total cholesterol and apolipoprotein B were lower at 6 mo (p < 0.01) in Italian breastfed infants than in Swedish ones. Lower concentrations at 6 and 12 mo of total cholesterol (p < 0.05, p < 0.05, respectively), apolipoprotein B (p < 0.05, p < 0.01) and triglycerides (p < 0.001, p < 0.01), and of apolipoprotein A1 (p < 0.01) at 12 mo, were found in the Italian formula group than in the Swedish one. In conclusion, plasma total cholesterol, apolipoprotein B and triglycerides were found to be lower in Italian infants than in Swedish infants during the second half of infancy. These findings may partly result from differences in fat compositions between Swedish and Mediterranean weaning diets and in total fat intake in late infancy. Differences in duration of breastfeeding and possibly in breast milk composition may also have influenced our results.     

The metabolism of free fatty acids and triacylglycerols by the fetal liver in a guinea pig model of intrauterine growth retardation.

The aim of this study was to determine whether intrauterine growth retardation (IUGR) is associated with an alteration in hepatic lipid metabolism. IUGR was induced in 25 guinea pigs by uterine artery ligation on gestational d 30. On d 62, after anesthesia, an infusion of [1-14C]-palmitic acid was given. Fetuses were exposed at 15, 30, and 45 min, and simultaneous maternal and umbilical venous blood samples were taken. Livers were divided into right lobe, right and left sublobes of the quadrate lobe, and left lobe. In control fetuses, plasma radiolipids rose in parallel with, but were about half the value of, maternal levels. In IUGR fetuses, plasma radiolipids were lower than in controls at 15 and 30 min but were comparable at 45 min. Most of the radiolipid in the maternal plasma was FFA, with only 6% incorporated into triglycerides at 45 min. In control and IUGR fetal plasmas, 36-37% of the radiolipid was triglycerides by 45 min. Radiolabel incorporation into the right lobe was less than into the left lobe and left half of the quadrate lobe in control and IUGR fetuses. Compared with controls, radiolabel incorporation in IUGR fetuses was less in some or all liver lobes at each time point. The proportion of label associated with FFA and triglycerides did not vary with time, between lobes, or between control and IUGR fetuses. The difference in uptake between lobes reflects their blood supply, implying that most FFA is extracted during the first passage of the umbilical venous blood. Growth retardation was not associated with compromised hepatic FFA metabolism.     

Attenuated lipid peroxidation in preterm infants during subsequent doses of intravenous lipids

The aim of this study was to determine whether the administration of a lipid emulsion containing less polyunsaturated fatty acids but rich in monounsaturated fatty acids causes less in vivo lipid peroxidation in preterm infants. The prospective intervention study included 13 infants with birth weights and gestational ages ranging between 1,100 and 2,660 g and from 28.4 to 32.9 weeks. All were in a stable condition and randomly allocated for a 3-hour infusion (0.16 g/kg/h) of an olive oil-based and a soybean oil + medium chain fatty acid (MCT) emulsion on 2 consecutive days. Expired pentane and plasma triglycerides (TGs) were measured before, during, and after the 3-hour infusion. Basal exhaled pentane averaged 9.4 +/- 7.0 pmol/kg/min (mean +/- SD). During the olive oil-based emulsion, exhaled pentane increased to 95.2 +/- 56.7, and during soybean oil + MCT it increased to 110 +/- 93.9 pmol/kg/min (p < 0.05 both from basal, n.s. between preparations). One hour after discontinuation of the infusion, exhaled pentane returned to 21.1 +/- 12.6 pmol/kg/min (p < 0.05 vs. basal). Combined data on expired pentane measurements demonstrated that on day 1 pentane peaked at 124 +/- 87.0 pmol/kg/min which was significantly attenuated to 57.5 +/- 24.4 pmol/kg/min after an identical dose of lipid on day 2 (p < 0.05). No difference in peak TGs was detected between the two preparations or the study days. Infusion of a constant dose of intravenous lipids on 2 subsequent days to the newborn infants is associated with a reduction in lipid peroxidation. This finding may be dependent on normal postnatal maturation or may represent an appropriate adaptive response aiming at a reduction in oxidative stress. Peroxidation of soybean oil + MCT and olive oil-based lipid emulsions was similar in the newborn infants.