Social support and social networks: their relationship to the successful and unsuccessful survival of elderly people in the community. An analysis of concepts and a review of the evidence.

Many studies suggest that there is a relationship between social support and physical and psychological health status, risk of institutionalization and mortality of the elderly. Although longitudinal analyses confirm these suggestions, all studies experience problems with network methodology, and none use comparable operational or working definitions. It is known that there is an effect between these variables, but the nature of the relationship is still unknown.

The development of novel hepatitis B vaccines.

The development of vaccines against hepatitis B has proceeded along four main lines. (i) Human plasma-derived vaccines are safe, effective, and in general use. (ii) Subunit polypeptide vaccines formulated in micelles have reached the stage of clinical trials.