Glutamine and arginine affect Caco-2 cell proliferation by promotion of nucleotide synthesis.

OBJECTIVE: We tested our hypothesis that 1) the major effect of Gln is as a nitrogen donor, not an energy source, for nucleotides (NT) and 2) the supplementation of culture medium with arginine (Arg) decreases the flux of glutamine (Gln) for conversion to Arg, thus accelerating NT synthesis. METHODS: Various concentrations of nucleosides (NS+NT) Gln, and glutamate (Glu) in culture were tested for their effect on Caco-2 cell proliferation. (Arg was tested in media with and without Gln to evaluate the Gln pathway. The incorporation of (15)N from L-[5-(15)N]-Gln into NTs of DNA was measured under different NS + NT and Arg concentrations.) RESULTS: The proliferation of Caco-2 cells was increased by NS + NT and Gln supplementation, but not by Glu. The effective concentration of NS + NT was 100-fold smaller than that of Gln. An Arg effect was observed only in the presence of Gln. The NT synthesis from Gln, as indicated by (15)N incorporation from L-[5-(15)N]-Gln, was increased by Arg supplementation and decreased by NS + NT supplementation. CONCLUSION: These results support our hypothesis that the effects of Gln and Arg on Caco-2 cell proliferation are by the promotion of NT synthesis and that the major role of Gln is not energy supply.

Nutrition during pregnancy may be associated with allergic diseases in infants.

The prevalence of allergic diseases is high in Japan, even in infants. Their risk for developing allergies is influenced by the antigens in the mother's diet during pregnancy. We hypothesized that, apart from the antigens, hypersensitivity induced through high energy and nutrient intake by mothers during pregnancy may be a factor for allergic diseases in their babies. In this study, we tried to confirm our hypothesis. Allergy histories of parents and their infants, body characteristics and food and nutrient intake were measured by a questionnaire and a food frequency questionnaire, respectively. A total of 2,642 responses were obtained (return rate, 94.7%). The major allergic diseases in the infants were atopic dermatitis (6.0%), food allergy (3.7%) and bronchial asthma or asthmatic bronchitis (3.2%). About 60% of the infants with allergies had a family history of allergies. Family history of allergy, age of infant, order of birth, head and chest circumferences of infants, BMI of mothers before pregnancy and delivery and intake of lipids (fat and vegetable oil) and vegetables by mothers related positively, and the intake of protein, carbohydrates and milk and its products correlated negatively with allergic diseases in the infants (p < 0.05). The results, together with previous reports, suggest that a high intake of energy and lipids (fat and vegetable oil) during pregnancy may accelerate allergic diseases in infants.