ABSTRACT. Nucleotide supplementation of adapted-milk formulas may be of interest for infant nutrition because nucleotides are involved in the synthesis of proteins and other macromolecules such as phospholipids, and thereby facilitate lipoprotein synthesis. To determine whether dietary nucleotides influence plasma lipoproteins in newborns, we have studied the plasma-lipoprotein concentrations and the composition of the major lipoprotein fractions during the first week of life in two groups of preterm infants fed formulas differing only in their nucleotide content. For comparison, two groups of term infants were studied under the same conditions. Lipoproteins were isolated by density ultracentrifugation, and the lipid and protein content were determined by standard methods; apolipoprotein A-I was determined immunologically. Nucleotide supplementation of formula in preterm infants increased all plasma lipoprotein concentrations. In addition, an increase in the plasma esterification rate was observed. However, total cholesterol concentrations were unchanged. The changes in lipoproteins concentrations were due mainly to an increase in apolipoprotein content. Nucleotides added to formulas affected term-infants' lipoproteins significantly less than to perterm infants. These findings suggest that dietary nucleotides may enhance the synthesis of lipoproteins during the early neonatal period, especially in preterm infants. 35: 112-116,1994) Abbreviations LCAT, lecithin/cholesterol-acyl transferase CMP, cytidine monophosphate UMP, uridine monophosphate IMP, inosine monophosphate PTI-NFF, preterm infants fed nucleotide-free formula PTI-NSF, preterm infants fed nucleotide-supplemented formula TI-NFF, term infants fed nucleotide-free formula TI-NSF, term infants fed nucleotide-supplemented formula Nucleotides are present in most food products as nucleic acids from which nucleotides are released after digestion (1). Nucleic acids as well as free nucleotides are found in human milk in significant amounts (2, 3), and the nutritional role of these components is currently under study. Dietary nucleotides seem to influence several aspects of neonatal development (4-9), but little is known about the influence of nucleotides in lipoprotein (Pcdiatr Rcs

We determined the effect of supplementing milk formula with nucleotides on plasma lipoproteins in small-for-gestational-age infants: 21 infants were fed a nucleotide-supplemented formula and 20 infants were fed the same nucleotide-free formula. On days 0, 3 and 7 after birth, major plasma lipoprotein fractions were analyzed for apolipoprotein and lipid composition. Compared with the control group, the group receiving nucleotides had increased total apoprotein concentrations in all lipoproteins as well as increased apo A-I in high-density lipoproteins and very low-density lipoproteins, and apo B-100 in very low-density lipoproteins and low-density lipoproteins. Very low-density lipoprotein cholesterol, low-density lipoprotein cholesterol and very low-density lipoprotein triglycerides increased in parallel to the changes in apoproteins. The cholesterol ester to unesterified cholesterol ratio was increased in low-density lipoproteins and, particularly, in high-density lipoproteins. These data support the hypothesis that lipoprotein metabolism in small-for-gestational-age infants is affected by dietary nucleotide supplementation, enhancing lipoprotein synthesis or secretion. Cholesterol esterification capacity paralleled the apo A-I increase, in agreement with the cofactor role of apo A-I on lecithin: cholesterol acyltransferase.

No abstract

Plasma lipoprotein levels and composition have been determined in preterm and small-for-gestational-age (SGA) infants, and compared to full-term infants, during the first week of life. Significantly lower levels of HDL and higher levels of VLDL were found in both preterm and SGA infants in comparison to full-term healthy infants. These results suggest a low capacity to metabolize VLDL. Preterm infants showed a behaviour similar to full-term infants with regard to the changes in lipoprotein composition. Small-for-gestational-age infants showed a higher lipoprotein lipid content than preterm infants. A low ratio of cholesteryl ester to free cholesterol (CE/FC) was found in both preterm and SGA infants suggesting a reduced lecithin: cholesterol acyl transferase (LCAT) activity. In preterm infants we observed no changes in the CE/FC ratio during the first week of life, whereas in SGA infants this ratio increased after birth.

The morphology of Trypanosoma humboldti n. sp. is described from living and stained specimens obtained from the blood of a catshark, Schroederichthys chilensis. This represents the first report of a trypanosome in fish from the eastern Pacific Ocean. It is distinguished by its size and apparent lack of pleomorphism. The presence of a leech, Branchellion ravenellii, attached to the catshark, raises the possibility that it can act as a vector. Additionally, this leech is recorded for the first time from the Pacific Ocean.