Do juvenile pilocytic astrocytomas undergo spontaneous malignant transformation : grounds for designation as hamartomas?
Juvenile pilocytic astrocytomas WHO grade I do not undergo spontaneous anaplastic transformation. Malignant transformations have only been demonstrated following radiation therapy. Earlier clinical and histopathological opinions regarding juvenile pilocytic astrocytomas as hamartomatous lesions are reaffirmed.
Thoracic epidural anesthesia with ropivacaine 0.2% does not decrease the tolerance to acute normovolemic anemia in healthy pigs. The hemodynamic compensation of acute anemia is fully preserved despite sympathetic block, and the critical hemoglobin concentration remains unaffected.