Hebrew University-Hadassah Medical School researchers have managed to reverse birth defects in mice using stem cells to replace defective brain cells. The work of Prof. Joseph Yanai and his colleagues was presented at the Tel Aviv Stem Cells Conference last spring and is expected to be published in 2009 at the seventh annual meeting of the International Society for Stem Cell Research in Barcelona. Neural and behavioral birth defects such as learning disabilities are particularly difficult to treat, compared to defects with known causes such as Parkinson's or Alzheimer's disease, because the prenatal teratogen - the substances that cause the abnormalities - act diffusely in the fetal brain, resulting in multiple defects. Yanai and associates were able to overcome this obstacle in lab tests by using mouse embryonic neural stem cells. These cells migrate in the brain, search for the deficiency that caused the defect and then differentiate into cells needed to repair the damage. In general, stem cells may develop into any type of cell in the body, but at a certain point they begin to commit to a general function, such as neural stem cells, destined to play a role in the central nervous system. At more advanced stages, the neural stem cells take on an even more specific role as neural or glial (supporting) cells. In the researchers' animal model, they were able to reverse learning deficits in the offspring of pregnant mice exposed to organophosphate (a pesticide) and heroin. This was accomplished by direct neural stem cell transplantation into the brains of the offspring. The recovery was almost 100 percent, as proved in behavioral tests. On the molecular level, brain chemistry of the treated animals was also restored to normal. The researchers then went one step further. Puzzled by the stem cells' ability to work even in those cases where most of them died out in the host brain, the scientists went on to discover that before they die, neural stem cells succeed in inducing the host brain itself to produce large number of stem cells that repair damage. This discovery, finally settling a major question in stem cell research, evoked great interest and was published earlier this year in one of the leading journals in the field, Molecular Psychiatry. WANT TO GO TO THE DENTIST Half of Israelis don't go to the dentist regularly, either because they feel they can't afford it or are scared of dental work. Young children who have never opened their mouths while sitting in a dentist's chair should not be afraid. Now dental hygienist Iris Zadik (email@example.com) has written a children's book, colorfully illustrated by Ronit David, to encourage kids to go to the dentist. Written in Hebrew and including advice for parents about when to take a child for a first checkup and how to avoid dental decay, the book stars a giraffe named Shauli who suddenly develops a toothache. He can't sleep, is not helped by a pain reliever, and was referred to Dr. Nadav, a friendly looking turtle. The problem is getting the patient into the clinic, as well as the difference in altitude between Shauli and the dentist. Waiting in the garden, the giraffe finds he can't get in; he even breaks a window when trying to get his head through it. His friends call the firefighters, who bring the tallest ladder they have, allowing the sweaty turtle to reach Shauli's mouth. A lower-left tooth found to be decayed is anesthetized, drilled and fixed with a shiny metal crown. The giraffe is advised to brush at least twice a day, avoid sweets and visit the clinic every few months for a checkup and also for cleaning. Before bidding Shauli goodbye, the turtle is asked to fix the damage to the windows and doors. The last page is dedicated to an explanation of giraffe lifestyle.