Infants' exploration of scented toys: effects of prior experiences

To evaluate breastfed infants' responses to scented objects, we videotaped the facial and bodily reactions of sixty-three infants as they explored, in succession, three toys that were identical in appearance but different in their characteristic odor. Two of the toys were scented with odorants previously shown to be transmitted to human milk, one with ethanol and the other with vanilla, whereas the third toy was unscented. Each videotape was subjected to frame-by-frame analysis to measure a variety of behaviors that are considered either to be exploratory in nature in that they lead to perceptual information about the object or to reflect the infants' hedonic reaction. Analyses of these behaviors revealed that the infants looked more and vocalized less in the presence of the vanilla-scented toy and spent less time manipulating the ethanol-scented toy when compared with the unscented toy. Moreover, differential exposure to the odors of ethanol and vanilla, as indicated by differential consumption of alcohol by a parent or use of vanilla-scented product by the mother, was related to differential responses to these odors. These findings suggest that human infants are able to detect and retain information about the chemical features of their environment.      

Critical Assessment of Methods Used to Measure Protein Synthesis In Human Subjects

The loss of body protein that frequently accompanies illness occurs through changes in protein synthesis and degradation. In human tissues, rates of protein synthesis can be assessed with stable isotopic tracer techniques and mass spectrometry. The basic principles of these methods are explained, and the advantages and drawbacks of the two main approaches, the constant infusion method and the flooding method, are described. Examples are given of the use of these methods to investigate protein synthesis and surgical trauma, pathologies of the gastrointestinal tract and the response of tumor growth to amino acid supplements.     

A TECHNIQUE FOR MEASURING BRAIN PROTEIN SYNTHESIS

Abstract— Mice were infused intravenously for varying periods of time with L-[U-¹⁴C]- tyrosine. The specific activity of free tyrosine in the blood and the brain, and of protein-bound tyrosine in the brain, was measured and the mean rate of protein synthesis calculated. The half-life of mixed brain proteins was found to be close to 4 days with infusions lasting 0.5–2 h.
The origin of the intracellular tyrosine pool was investigated and it was shown that 60 per cent of this was derived directly from the plasma tyrosine and 40 per cent from protein breakdown within the tissue.     

Marfella CG,Ohkawa Y,Coles AH,Garlick DS,Jones SN,Imbalzano AN. 2006. Mutation of the SNF2 family member Chd2 affects mouse development and survival. J Cell Physiol 209:162–171.

The original article to which this erratum refers was published in J Cell Physiol 2006; 209:162–171.