| 1 | Treatment depends on the lesions' symptoms and location. | |
| 2 | The lesions usually appear early in the course of HIV infection. | |
| 3 | Scientists have known for more than two decades that cancer is a disease of the genes. | |
| 4 | Since then, the institute' s brain disease model has been widely adopted. | |
| 5 | To study a disease, scientists like to look at cells from the diseased organ. |