Molecular genetics of supratentorial primitive neuroectodermal tumors and pineoblastoma.

In older patients, prophylaxis of herpesvirus infections mainly involves preventing the recurrence of herpes simplex virus (HSV) and complications of herpes zoster in immunocompetent patients, while in immunocompromised patients it is more concerned with the prevention of opportunistic virus reactivation. HSV ocular infection is the most frequent cause of corneal blindness in the US. The effectiveness of aciclovir 400mg twice daily in preventing the recurrence of HSV eye disease in immunocompetent patients has been well demonstrated. The issue of treatment duration for patients with highly recurrent ocular herpes remains unresolved. Post-herpetic neuralgia (PHN) is one of the most common neuralgic illnesses worldwide. Some progress in prevention of PHN has been made with a combination of antiviral therapy (famciclovir or valaciclovir), started within 72 hours of onset of the rash, and analgesic treatment. However, the best prevention of PHN is the prevention of herpes zoster disease, and the varicella vaccine is an option which over the next few years will be tested in clinical trials. For immunocompromised patients of any age, restoring immunity prevents herpesvirus disease, as demonstrated for cytomegalovirus (CMV) in AIDS patients receiving highly active antiretroviral therapy. Specific antiviral therapy during the initial period after transplantation could prevent reactivation of HSV or CMV in seropositive recipients. Whether pre-emptive therapy or prophylaxis with ganciclovir is the optimal approach against CMV remains controversial, and the relative merits and limitations of each approach may guide the choice. In stem cell transplantation, pre-emptive therapy with foscarnet avoids the neutropenia and related complications associated with ganciclovir. In renal transplant recipients, universal prophylaxis of CMV infection with valaciclovir has the same efficacy as ganciclovir. Although it is relatively toxic, cidofovir should be further evaluated because of its in vitro activity against most DNA viruses.