techniques of genetic engineering can be extended to gene replacement.
Infections, especially pneumonia and those of the urinary tract, are a major cause of disability and mortality in old persons. However, the exact extent of disability from infectious disorders in older people is largely unknown. Knowledge is incomplete about the prevention and treatment of infection in this population. Specific research opportunities include studies of the basic mechanisms of immune deficiency in older individuals, including changes at the cellular level involving T-cell subsets, natural killer cells, macrophages, and receptor-mediated responses. Vaccine development needs to take into account the special characteristics of the elderly population. Vaccines that can bypass the need for immune T cells and vaccines made with live attenuated organisms with antigen attached to a rigid backbone may be more effective in old people. These efforts should utilize new technologies such as DNA recombinant vaccines and genetically engineered attenuated viruses. The focus on immunosenescence is also directly related to the next research focus, cancer in older persons, since impaired immunity contributes to cancer development.
Cancer and its related complications are the number two cause of death in persons over the age of 65 (National Center for Health Statistics, 1989); for elderly persons death due to cancer is the second leading cause of lost years of life. The basis for the age-associated frequency of and disability related to cancer is unknown. In addition, efforts at primary (e.g., prevent onset of disease), secondary (e.g., prevent onset of complications of disease), and tertiary (e.g., treat complications of disease) prevention of cancer have been limited almost entirely to the younger population. For example, little information exists on the efficacy of smoking cessation programs and the efficacy and toxicity of standard chemotherapeutic regimens for those 65 years or older. As with several of the other suggested areas of research identified in this report, there is a clear and substantial overlap between the clinical research related to neoplasia and the focus on aging and cell proliferation suggested in the basic biomedical component of this research agenda. Reverse genetics, recombinant DNA products, and delivery systems using gene trans-