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This is a report of research on whether or not the addition of sugar to foods consumed by babies early in their feeding significantly alters later preference for sweetened or unsweetened foods. Twenty control babies were fed regular baby food (which already has additional sugar) for the first 3 months of their solid-food feeding experience; 20 experimental babies were fed a diet with no added sugar for a similar time period. The two groups were then studied during a 4-week period in which they were randomly assigned to four different sequences of sweetened and unsweetened food. Their reactions to sweetened and unsweetened food were scored according to parental interpretation of their preferences and according to how much food they consumed. Neither group was found to prefer sweetened or unsweetened food. This finding is in contradiction of other studies and common lay and clinical views that infants prefer sweetened foods. It would seem that if babies do not prefer sweet foods, there is certainly no reason to add sugar to commercial products.

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We examined the positive and negative effects of somatic mutation on antibody function using saturation mutagenesis in vitro to mimic the potential of the in vivo process to diversify antibodies. Identical mutations were introduced into the second complementarity determining region of two anti‐phosphocholine antibodies, T15 and D16, which share the same germline VH gene sequence. T15 predominates in primary responses and does not undergo affinity maturation. D16 is representative of antibodies that co‐dominate in memory responses and do undergo affinity maturation. We previously reported that > 50% of T15 mutants had decreased antigen binding capacity. To test if this high frequency of binding loss was unique to T15 or a consequence of random point mutations applicable to other combining sites, we analyzed the same mutations in D16. We show that D16 suffers a similar loss of function, indicating an equally high potential for B‐cell wastage. However, only D16 displayed the capacity for somatic mutation to improve antigen binding, which should enhance its persistence in memory responses. Mutation of residues contacting the haptenic group, as determined by molecular modeling, did not improve binding. Instead, productive mutations occurred in residues that either contacted carrier protein or were distant from the antigen binding site, possibly increasing binding site flexibility through long‐range effects. Targeting such residues for mutation should aid in the rational design of improved antibodies.

Participants reported the following problems, which were hindering the success of the programmes: problems in the ABC message; permissive campus environment; lack of entertainment; and students' perceptions about HIV/AIDS and their own vulnerability. Participants came up with suggestions for improving the initiatives. The authors discuss implications of the study findings for the university's initiatives.

The immune response to phosphocholine (PC)–protein is characterized by a shift in antibody repertoire as the response progresses. This change in expressed gene combinations is accompanied by a shift in fine specificity toward the carrier, resulting in high affinity to PC–protein. The somatically mutated memory hybridoma, M3C65, possesses high affinity for PC–protein and the phenyl-hapten analogue, p-nitrophenyl phosphocholine (NPPC). Affinity measurements using related PC–phenyl analogues, including peptides of varying lengths, demonstrate that carrier determinants contribute to binding affinity and that somatic mutations alter this recognition. The crystal structure of an M3C65–NPPC complex at 2.35-Å resolution allows evaluation of the three light chain mutations that confer high-affinity binding to NPPC. Only one of the mutations involves a contact residue, whereas the other two have indirect effects on the shape of the combining site. Comparison of the M3C65 structure to that of T15, an antibody dominating the primary response, provides clear structural evidence for the role of carrier determinants in promoting repertoire shift. These two antibodies express unrelated variable region heavy and light chain genes and represent a classic example of the effect of repertoire shift on maturation of the immune response.

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