Building on the Resource-Based View of the firm, we advance the idea that a firm’s customer network can be a strategic asset. We suggest that network effects are a function of network size (i.e., installed customer base) and network strength (i.e., the marginal impact of a unit increase in network size on demand). We empirically study these network effects in the 16-bit home video game industry...

Multiple primary neoplasms are defined as multiple occurrences of malignant neoplasms of differing histological origin in the same individual. The present study describes the case of a 46-year-old male who suffered from two synchronous primary malignant neoplasms, an osteoclastoma of the left femoral trochanter and an anaplastic astrocytoma of the the Sylvian fissure area in the brain. At the 6...

OBJECTIVE The exact cell of origin of subependymal giant cell astrocytoma is debated but most currently consider the tumor in the astrocytic category. Mutations and subsequent biallelic inactivation of TSC1 encoding hamartin, or TSC2 encoding tuberin appear to be the underlying genetic aberrations. Inactivation leads to loss of proteins that inhibit mammalian target of rapamycin (mTOR ) disrupt...

OBJECTIVES Intraventricular astrocytomas (subependymal giant cell astrocytomas) of tuberous sclerosis have a poor prognosis due to the obstruction of CSF flow. The aim of this study was to determine whether they could be differentiated during childhood and at an early preclinical stage, from subependymal nodules without any growing potential. METHODS The first two MRIs of all children referre...

Rapamycin inhibits the mTOR (target of rapamycin) pathway and extends lifespan in multiple species. The tuberous sclerosis complex (TSC) protein is a negative regulator of mTOR. In humans, loss of the TSC protein results in a disorder characterized clinically by the growth of benign tumors in multiple organs, due to overactivation of mTOR inhibition. Subependymal giant cell astrocytomas (SEGAs)...

BACKGROUND Tuberous sclerosis complex (TSC) is an autosomal dominant disorder. It is characterized by seizures, mental retardation and hamartomatous lesions, including facial angiofibroma, subependymal giant cell astrocytoma, cardiac rhabdomyoma and renal angiomyolipoma (AML). AMLs can bleed severely in the retroperitoneal space. CASE PRESENTATION Herein, we present the case of a TSC patient ...

BACKGROUND Giant cell ependymoma of the filum terminale is a rare variant, generally manifested as a well-circunscribed intradural mass with an indolent biological behavior. CASE PRESENTATION We describe the case of a 48-year-old Mexican female who non-relevant past medical history, that developed a GCE of the filum terminale. Magnetic resonance imaging and computed tomography revealed the pr...

Multinucleated giant cells, formed by the fusion of monocytes/macrophages, are features of chronic granulomatous inflammation associated with infections or the persistent presence of foreign material. The tetraspanins CD9 and CD81 regulate multinucleated giant cell formation: soluble recombinant proteins corresponding to the large extracellular domain (EC2) of human but not mouse CD9 can inhibi...

Fibrillary astrocytoma, the most common primary central nervous system neoplasm, is infiltrating, rapidly proliferating, and almost invariably fatal. This contrasts with the biologically distinct pilocytic astrocytoma, which is circumscribed, often cystic, slowly proliferating, and associated with a favorable long-term outcome. Diagnostic markers for distinguishing pilocytic astrocytomas from i...