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Through the ages, walking has been a stable characteristic of the human condition. Of recent, however, it is under threat, Ian Roberts, of the Institute of Child Health, London, examines the twentieth century trend toward less walking, exploring its origins and the cultural, biological and health-related ramifications of the decline of the pedestrian.
Two new clinically effective melanoma vaccines exploit improvements in the way tumor antigens can be ‘presented’ to the immune system (pages 321–327 and 328–332).
Antibodies that cross react with the tumor antigen MUC1 switch a cellular immune response to a humoral one with implications for the immunotherapy of cancer (pages 315–320).
A recently developed gene targeting procedure shows promise for the efficient correction of genetic defects in vivo but many questions have yet to be answered (pages 285–290).
Activation of the contact system on bacterial surfaces provides a mechanism by which this cascade of proteolytic enzymes contributes to septic shock and inflammation (pages 298–302).
Evolutionary patterns of virus replication and distribution in lymphoid tissue during the early phases of HIV infection have not been delineated. Lymph node (LN) biopsies were excised from patients at different times after the estimated time of primary infection. Within 3 months of the acute viral syndrome, HIV was mostly present in individual virus-expressing cells in LNs; trapping of virions in the follicular dendritic cell (FDC) network was minimal or absent, but was the predominant form of HIV detected in LNs of subjects with chronic infection, either recent (4–20 months after primary infection) or long-term (>2–3 years after primary infection). Plasma viremia was significantly higher in patients during the first 3 months than in those recently infected; however, there were no significant differences in the number of virus-expressing cells per square millimeter of LN tissue in these two groups. Numbers of virus-expressing cells in lymphoid tissue were significantly lower in the subjects with long-term infection than in the other two groups. Therefore, during the transition from primary to chronic HIV infection, the level of HIV replication in lymphoid tissue remains elevated despite the fact that viremia is significantly downregulated. These findings have implications for therapeutic strategies in primary HIV infection and in recent seroconvertors.
