Breast-fed infants achieve a higher rate of brain and whole body docosahexaenoate accumulation than formula-fed infants not consuming dietary docosahexaenoate

Docosahexaenoate (DHA) has been increasingly recognized as an important fatty acid for neural and visual development during the first 6 mon of life. One important point of controversy that remains is the degree to which adequate levels of DHA can be acquired from endogenous synthesis in infants vs. what should be provided as dietary DHA. We have approached this problem by a retrospective analysis of published body composition data to estimate the actual accumulation of DHA in the human infant brain, liver, adipose tissue, remaining lean tissue, and whole body. Estimating whether infants can synthesize sufficient DHA required comparison to and extrapolation from animal data. Over the first 6 mon of life, DHA accumulates at about 10 mg/d in the whole body of breast-fed infants, with 48% of that amount appearing in the brain. To achieve that rate of accumulation, breast-fed infants need to consume a minimum of 20 mg DHA/d. Virtually all breast milk provides a DHA intake of at least 60 mg/d. Despite a store of about 1,050 mg of DHA in body fat at term birth and an intake of about 390 mg/d α-linolenate (α-LnA), the brain of formula-fed infants not consuming DHA accumulates half the DHA of the brain of breast-fed infants while the rest of the body actually loses DHA over the first 6 mon of life. No experimental data indicate that formula-fed infants not consuming DHA are able to convert the necessary 5.2% of α-LnA intake to DHA to match the DHA accumulation of breast-fed infants. We conclude that dietary DHA should likely be provided during at least the first 6 mon of life.     

Fatal asphyxiations in children involving drawstrings on clothing

Injuries account for more deaths and hospital admissions among children and adolescents than all diseases combined. The authors report two deaths by asphyxiation that resulted from drawstrings on the children's clothing becoming entangled on slides. Although such incidents are not common, they are preventable. The authors urge physicians to counsel parents and guardians to remove drawstrings from children's clothing, and they call upon the government and the clothing industry to work toward improving the safety standards for the design, manufacture and importation of children's clothing and banning the sale of children's clothing with drawstrings in Canada. In addition, they provide several resources for readers interested in helping reduce playground hazards in their communities.     

Peroxynitrite modification of glutathione reductase: modeling studies and kinetic evidence suggest the modification of tyrosines at the glutathione disulfide binding site

The catalytic properties of glutathione reductase for its substrate,glutathione disulfide, were altered following a 60 s exposureto a 100-fold molar excess of peroxynitrite; the K_M value wasincreased by {small tilde}2.5-fold and the V_max value was decreasedby {small tilde}1.7-fold. The kinetic alterations are thoughtto result from nitrotyrosine formation as the intrinsic Tyrfluorescence is diminished. The UV-visible spectrum of glutathionereductase exhibited absorbance at {small tilde}423 nm, characteristicof nitrotyrosine. In addition, the presence of nitrotyrosinehas been detected by Western immunoblots with an anti-nitrotyrosineantibody. The peroxynitrite-induced inactivation is not observedin the presence of excess glutathione disulfide. However, excessNADPH offered no protection against peroxynitriteinduced inactivation.These observations suggest that the modification of {small tilde}1.8Tyr per subunit, at or near the glutathione disulfide bindingdomain, probably results in the observed catalytic alterations.To test this hypothesis, the two tyrosines closest to the glutathionedisulfide binding domain (Tyr114 and Tyr106), as indicated bythe X-ray crystallographic data [Karplus and Schulz (1989) J.Biol. Chem, 210,163–180], were each converted to nitrotyrosinesby molecular modeling and the structure energy was minimized.These theoretical calculations indicate that the bond lengthsbetween Tyr114-O and the Gly-N and Cys II-N of glutathione disulfidebound to glutathione reductase (Karplus and Schulz, 1989) increasedby 3.0 and 4.3 Å, respectively, upon nitration. In thecase of Tyr106, the O–Cys II-N distance also increasesby {small tilde}1.6 Å. The loss of these hydrogen bondingcontacts is likely to result in the observed catalytic alterationsupon reaction with peroxy-nitrite.