Dietary nucleotides enhance plasma lecithin cholesterol acyl transferase activity and apolipoprotein A-IV concentration in preterm newborn infants

The activity of lecithin cholesterol acyl transferase (LCAT), a key enzyme in lipoprotein metabolism, is low in newborn preterm infants. It has been suggested that a normal gastrointestinal function might be necessary to induce a postnatal increase of LCAT activity because apoproteins A-I and A-IV (apoA-I and apoA-IV) synthesized in considerable amounts in the intestine are known activators of LCAT. Dietary nucleotides have been reported to enhance intestinal growth and maturation; therefore, we hypothesized that nucleotide supplementation to formulas for preterm infants may influence LCAT activity. To investigate this hypothesis, two groups of preterm infants were fed either a nucleotide-free formula or a nucleotide-supplemented formula during the first month of life. The plasma LCAT activity, plasma levels of apoA-I and apoA-IV, plasma cholesteryl esters, and plasma fatty acid composition of cholesteryl esters and phospholipids were then determined. Infants receiving nucleotides had higher LCAT activities and apoA-IV levels than those receiving the nucleotide-free formula for a few weeks. The changes in apoA-IV levels were highly correlated with those of the LCAT activities. However, there were no significant correlations between changes in LCAT activity and plasma cholesteryl esters or phospholipids. These findings indicate that nucleotide supplementation to formulas for preterm infants may improve dietary lipid tolerance by enhancing plasma LCAT activity, probably as a result of an increase in apoA-IV plasma concentrations; they also suggest that nucleotides may enhance apoA-IV synthesis in the intestine during the neonatal period.

Diet and the essential fatty acid status of term infants

Long-chain polyunsaturated fatty acids with 20 and 22 carbon atoms (LCPs) seem to play an important role during the rapid development of the infant brain in the late fetal and early postnatal period. These LCPs are integral constituents of biological membranes and they are involved in the regulation of functional properties like fluidity, permeability and activity of membrane-bound enzymes. Human milk contains LCPs in an amount of 0.5-3 wt% of total fatty acids, whereas commercially available infant formulae are almost free of them. Recently, several clinical trials, primarily with preterm infants, have reported that the content of LCPs in the blood and a functional parameter like visual acuity correlate with the content of LCPs in the diet. In this clinical trial we studied the effect of different diets on the fatty acid pattern of plasma and erythrocyte lipids of healthy term infants during the first 3 months of life. Breast-fed infants were compared with formula-fed babies who received a commercially available formula without LCPs or a new experimental formula enriched with LCPs that was similar to human milk. The results indicate that the introduction of milk feeding leads to marked differences in the blood lipid composition during the first months of life, independent of the feeding regimen. Secondly, the supplementation of a formula with LCPs seems to result in a blood lipid composition similar to infants fed with human milk. This supports the hypothesis that the newborn term infant has a limited desaturating capacity and depends on an exogenous supply of LCPs during the first months of life.

Apolipoprotein and lipid composition of plasma lipoproteins in neonates during the first month of life

In this study the lipid and apoprotein profiles were investigated in newborns at 0, 7, and 30 days of life. The plasma lipoproteins were separated both by ultracentrifugation and gel filtration in order to compare the patterns obtained by the two techniques. At birth, the apo E concentration is comparable to that measured in adults, but its distribution among lipoproteins is significantly different as more than 80% of the plasma apo E belongs to high-density lipoproteins (HDL). At 7 and 30 days the plasma apo E concentrations are close to the values at birth, but a significant redistribution occurs from HDL to very low-density lipoproteins. By analogy with apo B, the plasma apo CIII concentration is low at birth and increases between 0 and 7 days by a factor of about two. Plasma triglycerides increase significantly during the first week of life so that the apo CIII increase is most pronounced in very low-density lipoproteins. These lipoproteins therefore become enriched in apo E, apo CIII and triglycerides between 0 and 7 days. At birth, a distinct HDL fraction, enriched in apo E, apo AII and cholesterol (HDLE), could be detected. To compensate for the low LDL levels, this HDLE fraction might function as an additional source for cholesterol delivery to peripheral tissues via the apo (B, E) receptor. At later age, low-density lipoprotein synthesis is enhanced, apo E is transferred to very low-density lipoproteins, and cholesterol delivery via the HDLE becomes less important.(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma apoprotein and lipid patterns in newborns: influence of nutritional factors

In this study the plasma lipid and apoprotein concentrations have been assayed in 80 full-term newborns, at 0, 7 and 30 days of life, and the data have been analyzed as a function of the composition of the diet. The total cholesterol, HDL cholesterol, the apo A-I, A-II and B protein concentrations were followed in 4 groups of infants receiving respectively breast-feeding, adapted formulae I, II with a P/S ratio close to that of maternal milk and a formula III enriched with polyunsaturated fatty acids. After 7 and 30 days the infants receiving the adapted formulae I and II have plasma lipid and apoprotein values similar to those of the breast-fed infants indicating a parallel evolution of the lipids and apoproteins in the three groups. The lipid and apoprotein patterns were significantly different in the group of infants receiving a diet enriched with polyunsaturated fatty acids. The total and VLDL-LDL cholesterol and the apo B protein concentrations are significantly lower than in the breast-fed infants after 7 days, and these differences become more pronounced after 30 days. These results suggest that the fatty acid composition of the diet influences the lipid and lipoprotein synthesis in newborns, specially by decreasing the lipid and apoprotein concentrations of the VLDL-LDL fraction.

Familial hyperlysinaemia due to L-lysine alpha-ketoglutarate reductase deficiency: results of attempted treatment

A mentally retarded male infant with persistent hyperlysinaemia due to L-lysine alpha-ketoglutarate reductase deficiency is described. The effect of dietary restriction of lysine on his mental and behavioural development was examined. By restricting daily dietary lysine to 5.5 mg/kg body weight the fasting serum lysine became normal. Urinary lysine also became normal and the secondary metabolites homocitrulline, homoarginine, N alpha-acetyllysine and N epsilon-acetyllysine were no longer detected. After control of serum lysine for 2.5 y it was felt that the patient's social behaviour, but not his mental development, had improved somewhat.

A new variant of glucosephosphate isomerase deficiency: GPI-Kortrijk

A new case of glucosephosphate isomerase deficiency in a Belgian family is described. The activity of the enzyme was decreased to about 25-30% of the normal value. Characterization of the defect enzyme showed a decreased thermostability. Heating of the enzyme at 45 degrees C showed a loss of activity of 50% after 90 min. The pH-optimum and the KM-value for fructose 6-phosphate were normal. The electrophoretic pattern showed a faster migration. The variant described here differs from all known variants. Therefore we propose to give to this new variant the name GPI-Kortrijk.

Excessive hepatic glycogen storage in glucosephosphate isomerase deficiency

Excessive amounts of glycogen were found in liver and erythrocytes of a patient suffering from generalized glucosephosphate isomerase deficiency. A low carbohydrate diet, frequent meals and avoidance of peak carbohydrate challenges resulted in a significant decrease of liver volume without affecting the haematological condition. The possible mechanism of these findings are discussed.

Glucosephosphate isomerase deficiency, a new variant in a Dutch family. Case report

The clinical course and the biochemical findings are reported from a patient suffering from glucosephosphate isomerase (G.P.I EC 5.3.1.9) deficiency type Nijmegen. This disorder decleares itself as a non-spherocytic hemolytic anemia, presenting in the neonatal period. In the patient hemolysis was of the same degree during the years. However, trivial infections could often trigger an increase in hemolysis requiring treatment by blood transfusions. Enzyme studies revealed that the GPI deficiency in this patient was caused by a double heterozygous state for two different GPI deficient alleles. The presence of one of these deficient alleles in the proband's parents and grandparents, was not accompanied by any sign of hemolysis, as for instance a shortened red-cell survival.

Familial occurrence of the g syndrome

We report the familial occurrence of the G syndrome of multiple congenital anomalies affecting a mother and her three sons. All showed the characteristic syndromal facies, a low total ridge count, pronounced hypertelorism, and mild mental retardation, and severe dysphagia in infancy which improved with age but persisted in the boys (it has disappeared in the mother). One of the boys had a left cleft lip and cleft palate, another had a unilateral cleft lip. All boys had hypospadias: penile in two (with descended testes) and perineal in another (with cryptorchidism). Familial occurrence in this family is compatible with autosomal dominant inheritance.