Effect of dietary triacylglycerol fatty acid positional distribution on plasma lipid classes and their fatty acid composition in preterm infants.

Seven premature infants were each fed, for 1 wk in a crossover design. The beta formula contained triacylglycerols resembling the stereoisomeric structure of human milk fat (25.4% by wt 16:0, 76.1% of which is at the sn-2 position), whereas in the alpha formula 87.3% of total 16:0 (25.7% by wt was at the sn-1,3 positions. Plasma lipids and their fatty acid compositions were determined at the end of each 1 wk study period. Infants fed with the beta formula had higher percentages of palmitic acid in plasma sterol esters, triacylglycerols, and free fatty acids, and lower linoleic acid in triacylglycerols than with the alpha formula. Premature infants fed formulas with triacylglycerols 16:0 predominantly in the sn-2 rather than the sn-1,3 positions had alterations in their plasma fatty acids consistent with enhanced absorption of 16:0 from the sn-2 compared with the sn-1,3 positions.

Feeding premature newborn infants palmitic acid in amounts and stereoisomeric position similar to that of human milk: effects on fat and mineral balance.

The effect of the structure of human milk triglycerides on intestinal fat absorption remains controversial. Twelve infants were each fed, for 1 wk in a crossover design, two formulas that differed only in triglyceride configuration. The "beta" formula contained triglycerides similar to those in human milk (26% palmitic acid, esterified predominantly to the sn-2 position) whereas in the "alpha" formula, which contained triglycerides similar to those in formulas currently marketed, palmitate was mainly at the sn-1,3 positions. Fatty acid, fat, and mineral balances were measured at the end of each 1-wk period. Myristic, palmitic, and stearic acids were absorbed better from the beta formula, but total fat excretion was not reduced. During the feeding of beta formula fecal calcium excretion was lower, urinary calcium higher, and urinary phosphate lower. A formula containing triglycerides similar to those in human milk has significant effects on fatty acid intestinal absorption and improves mineral balance in comparison with a conventional formula.

The effect of alterations in physical and chemical characteristics on TOBEC-derived body composition estimates: validation with non-human models.

The measurement of total-body electrical conductivity (TOBEC) has become one of the standard methods for the estimation of body composition in infants. We investigated, using non-human models, the effect on the accuracy of TOBEC-derived body composition estimates of alterations in physical and chemical characteristics of the fat-free mass (FFM). The effect of electrolyte type, concentration and volume on TOBEC was determined using 2, 3 and 51 solutions of six different chlorides and sodium bicarbonate. Equimolar concentrations yielded TOBEC values in accordance with known ion conductivities: H+ >> Ca2+ > Mg2+ > K+ > Na+ > Li+ and Cl- > HCO3-. The behaviour of these solutions was described very accurately over a wide range of concentrations (1-200 mM) by a simple exponential law. Dissolved egg-white protein, glycine and L-glutamine elicited no TOBEC signal. In vitro, using polyethylene bottles filled with physiologic saline, in the interval of 2-45 degrees C a linear relation was observed between temperature and TOBEC. Below the freezing point no TOBEC signal was elicited. The effect of tissue autolysis and body temperature on TOBEC was examined by repeated measurements of TOBEC and temperature in seven fresh infant minipig cadavers. Five minipigs were allowed to cool. Shortly after death TOBEC decreased by 2.5% per degrees C. Two animals were kept at constant temperature. The TOBEC signal showed a gradual increase of 9% after 7 h due to autolysis. We conclude that in vivo TOBEC measurements are affected by ion concentration (e.g. non-isotonic hydration changes), geometry (e.g. deviations in body shape), temperature (e.g. fever, skin cooling) and tissue autolysis (measurements after death). Proteins, molecules with strong dipole moments and ions trapped in crystalline structures do not significantly affect the TOBEC reading.

Pneumococcal conjugate vaccination does not induce a persisting mucosal IgA response in children with recurrent acute otitis media.

AIM: In a prospective controlled study in young children with a history of recurrent acute otitis media, we analyzed the salivary IgA and IgG antibody titers upon vaccination with a 7-valent pneumococcal conjugate vaccine (PCV) given once or twice, followed by a 23-valent polysaccharide booster vaccination. METHODS: Salivary IgA and IgG antibody concentrations to vaccine serotype 6B, 14, 18C and 19F were measured by enzyme immunoassay in 38 samples of children vaccinated with PCV and 45 control samples. In the PCV group, 12 samples were taken prior to vaccination, 12 samples 4 weeks after the polysaccharide booster (8 months after the first conjugate vaccination) and 14 samples 7 months after the last vaccination (14 months after the first conjugate vaccination). In the control group 15 children were sampled at each of these three time points. RESULTS: We observed an increase in salivary IgG antibody concentrations against serotype 6B, 14, and 18C 14 months after the primary vaccination in children vaccinated with PCV twice, although this was significant for serotype 14 only. There was no increase in salivary IgG antibody in children vaccinate with PCV once nor in control children. IgA antibody titers increased significantly after 8 and after 14 months in both the pneumococcal vaccine recipients and the controls. However, the observed increase in mean antibody titers was significantly higher in control children compared to the PCV group. CONCLUSION: We suggest that repeated pneumococcal conjugate vaccination is necessary to induce an increase in salivary IgG antibodies and effectuate clearance of S. pneumoniae from the nasopharyngeal mucosa of children with recurrent acute otitis media. We hypothesize that the increase in salivary IgA is caused by the local boosting of the mucosal immune response by carriage and recurrent infections, which occurs less often in the PCV group compared to the control children.

Effects of early amino acid administration during total parenteral nutrition on protein metabolism in pre-term infants.

1. We investigated the effects of starting amino acid administration on post-natal day 2 on protein turnover and nitrogen balance in appropriate-for-gestational-age, very-low-birth-weight infants. Eighteen infants were divided into two groups. Group A received from day 2 onwards an amino acid solution, whereas group B started on this solution after day 4. Both groups were exclusively parenterally fed, 200 kJ day-1 kg-1 on post-natal days 3 and 4. Group A (birth weight 1.5 +/- 0.3 kg) received 4.6 g of glucose, 1.9 g of fat and 2.3 g of amino acids day-1 kg-1 body weight. Group B (birth weight 1.4 +/- 0.2 kg) received 7.0 g of glucose and 1.9 g of fat day-1 kg-1 body weight. 2. At post-natal day 3, a primed constant infusion of 3 mg of [15N]glycine day-1 kg-1 was given. Protein flux, protein synthesis and protein breakdown were calculated from the 15N enrichment in urinary ammonia. In five out of nine infants in group B no plateau of 15N enrichment in urinary urea could be detected, whereas in group A two out of nine infants did not reach a plateau. For this reason we did not use the end product urea for our calculations. 3. The administration of the amino acids resulted in a higher protein flux (6.9 +/- 1.5 g day-1 kg-1 versus 5.2 +/- 0.9 g day-1 kg-1) and a higher protein synthesis rate (6.0 +/- 1.4 g day-1 kg-1 versus 4.6 +/- 0.8 g day-1 kg-1) in group A.(ABSTRACT TRUNCATED AT 250 WORDS)

The very low birth weight premature infant is capable of synthesizing arachidonic and docosahexaenoic acids from linoleic and linolenic acids.

Infants fed formulas devoid of long-chain polyunsaturated fatty acids (LCP) exhibit low plasma LCP concentrations and have poorer retinal and neurologic development in comparison with their human milk-fed counterparts. It is not known whether the low plasma LCP concentrations result from an impaired biosynthetic capacity, a high need or a low dietary intake. With stable isotope technology and high sensitivity tracer detection using gas chromatography-isotope ratio mass spectrometry we measured the conversion of [13C]linoleic acid (C18:2n-6) and [13C]linolenic acid (C18:3n-3) into their longer chain derivatives in five 1-mo-old formula-fed preterm infants (birth weight 1.17 +/- 0.12.kg and gestational age 28.4 +/- 1.3 wk). Carbon-13-labeled linoleic acid and inolenic were mixed with the formula and administered continuously for 48 h. Both tracers were rapidly incorporated in plasma phospholipids, and their metabolic products including arachidonic acid (C20:4n-6) and docosahexaenoic acid (C22:6n-3) became highly enriched. We demonstrate that the preterm infant is capable of synthesizing LCP from their 18-carbon precursors, and our data do not support the hypothesis that a reduced delta 6 desaturation is a main factor leading to low arachidonic acid and docosahexaenoic acid levels.

Plasma and red blood cell fatty acid of very low birth weight infants fed exclusively with expressed preterm human milk.

The fatty acid composition of plasma phospholipids, triglycerides, sterol esters, and red blood cell phospholipids were determined at birth and again on d 7, 14, and 28 of life in 22 very low birth weight infants (birth weight 1180 +/- 290 g, gestational age 29.8 +/- 2.4 wk) fed exclusively with preterm human milk starting from the first hours postpartum. Milk intake was recorded daily, and intakes of fat and individual fatty acids were measured weekly. The intakes of linoleic acid and linolenic acid rose significantly during the study period, so did their incorporation into plasma and red blood cell lipids. The intakes of arachidonic acid (29.2 +/- 2.4 versus 30.4 +/- 2.1 mg.kg-1.day-1) and docosahexaenoic acid (18.8 +/- 1.7 versus 17.0 +/- 1.2 mg.kg-1.day-1) on d 14 and 28, respectively, were not different; however, their plasma levels declined significantly. The percentages of arachidonic acid declined in all plasma and red blood cell lipids, whereas the fall of docosahexaenoic acid was more notable in triglycerides and sterol esters, intermediate in plasma phospholipids, and less pronounced in red blood cell phospholipids. We conclude that very low birth weight infants fed exclusively with preterm milk, which unlike most preterm formulas contains long chain polyunsaturated fatty acids, exhibit declining levels of arachidonic acid and docosahexaenoic acid from birth up to 28 d of life.

Structural position and amount of palmitic acid in infant formulas: effects on fat, fatty acid, and mineral balance.

The structure of the triglycerides (TG) in human milk (HM) differs from those of vegetable oils used in infant formulas. In HM, palmitic acid is predominantly esterified to the center or beta-position of the TG, in vegetable oil, it is mainly at the external or alpha-positions. These differences in configuration affect intestinal fat absorption. Fat and mineral balances were investigated in three groups of 9 healthy term infants aged 5 weeks. Infants were randomly assigned to receive one of the three study formulas from birth: (a) formula beta, resembling the structure of HM fat most closely (24% palmitic acid, 66% esterified to beta-position), (b) formula intermediate (24% palmitic acid, 39% esterified to the beta-position), and (c) regular formula (20% palmitic acid; 13% esterified to the beta-position). Fat absorption was highest in infants fed the beta formula (97.6 +/- 0.9%), intermediate in those fed with the intermediate formula (93.0 +/- 1.8%), and lowest in infants receiving the regular formula (90.4 +/- 4.6%). Fecal calcium excretion was significantly lower in the beta group than in the other two groups (43.3 +/- 18.1 vs. 59.9 +/- 15.1 vs. 68.4 +/- 22.3 mg.kg-1.day-1 for beta, intermediate, and regular respectively). Dietary TG containing palmitic acid predominantly at the beta-position, as in HM, have significant beneficial effects on the intestinal absorption of fat and calcium in healthy term infants.