Steven D Chang

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The mechanistic target of rapamycin complex 1 (mTORC1) pathway regulates organismal growth in response to many environmental cues, including nutrients and growth factors. Cell-based studies showed that mTORC1 senses amino acids through the RagA-D family of GTPases (also known as RRAGA, B, C and D), but their importance in mammalian physiology is unknown.(More)
PURPOSE Given the neurocognitive toxicity associated with whole-brain irradiation (WBRT), approaches to defer or avoid WBRT after surgical resection of brain metastases are desirable. Our initial experience with stereotactic radiosurgery (SRS) targeting the resection cavity showed promising results. We examined the outcomes of postoperative resection cavity(More)
OBJECTIVE Microsurgical resection of benign intradural extramedullary spinal tumors is generally safe and successful, but patients with neurofibromatosis, recurrent tumors, multiple lesions, or medical problems that place them at higher surgical risk may benefit from alternatives to surgery. In this prospective study, we analyzed our preliminary experience(More)
Despite decades of clinical trials investigating new treatment modalities for glioblastoma multiforme (GBM), there have been no significant treatment advances since the 1980s. Reported median survival times for patients with GBM treated with current modalities generally range from 9 to 19 months. The purpose of the current study is to retrospectively review(More)
OBJECTIVE Stereotactic radiosurgery has been used for nearly 2 decades to treat hemangioblastomas, particularly those that are in surgically inaccessible locations or that are multiple, as is common in von Hippel-Lindau disease. There is a paucity of long-term published radiosurgical treatment outcomes, particularly for spinal lesions, in a large patient(More)
OBJECT The goal of this study was to determine the effect of hydrocephalus on cerebrospinal fluid (CSF) production rates in patients with acute and chronic hydrocephalus. METHODS The authors studied CSF production both in patients presenting with acute and chronic hydrocephalus, and patients with Parkinson disease (PD) of a similar mean age, whose CSF(More)
BACKGROUND AND PURPOSE To determine the effectiveness and safety of image-guided robotic radiosurgery for spinal metastases. MATERIALS/METHODS From 1996 to 2005, 74 patients with 102 spinal metastases were treated using the CyberKnife at Stanford University. Sixty-two (84%) patients were symptomatic. Seventy-four percent (50/68) of previously treated(More)
It is widely recognized that animals respond to odors by generating or modulating specific motor behaviors. These reactions are important for daily activities, reproduction, and survival. In the sea lamprey, mating occurs after ovulated females are attracted to spawning sites by male sex pheromones. The ubiquity and reliability of olfactory-motor behavioral(More)
OBJECT Hemangiopericytomas represent a small subset of meningeal tumors. Despite their relatively uncommon nature, they are aggressive tumors known for recurrence. Resection is the standard treatment in most, although regrowth and metastases are common even after resection. The authors evaluate the role of stereotactic radiosurgery in the treatment of(More)
BACKGROUND Risk factors for poor outcome in the treatment of very large (≥20-24 mm) and giant (≥25 mm) intracranial aneurysms remain incompletely defined. OBJECTIVE To present an aggregate clinical series detailing a 24-year experience with very large and giant aneurysms to identify and assess the relative importance of various patient, aneurysm, and(More)