Researchers have disarmed the blood-brain barrier sentry that keeps a potential treatment for stroke and Alzheimer's disease from getting into the brain. The brain is protected by the blood-brain barrier (BBB), a gate-keeping system of cells that lets in nutrients and keeps out foreign substances. The blood-brain barrier passes no judgment on which foreign substances are trying to get into the brain to treat diseases and which are trying to do harm, so it blocks them without discrimination. (Source: ScienceDaily Headlines)