1.   Both elderly people and astronauts experience muscle loss, decreased bone density, sleep disturbances, hormone imbalances, weakened immune defenses and problems with balance and orientation.

2.   But it is more than enough to kindle a raging infection if either antiviral drugs or immune defenses cannot keep HIV suppressed to such low levels.

3.   He was cited especially for three important theories of immunology that together offered a coherent general image of the immune defenses.

4.   Other small preliminary studies are under way of therapeutic vaccines designed to boost immune defenses in those already infected with the virus, and they have shown some promise.

5.   Repeated heavy marijuana smoking has lessened air capacity and immune defenses, and caused respiratory symptoms and ominous cell changes.

6.   The evidence so far is still anecdotal, but a few patients around the world have mounted immune defenses against HIV after stopping all multidrug therapy.

7.   The newly discovered virus quickly finds a way to elude immune defenses that normally eliminate molecules from a foreign species.

8.   The second theory presented an inclusive picture of how the immune defense system develops and matures.

9.   They say the boy evidently fought off infection with HIV, the AIDS virus, through the action of his natural immune defenses and apparently was only transiently infected.

10.   They say the boy evidently fought off the HIV infection with his natural immune defenses.