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 28,634 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tuberous sclerosis complex is a disease caused by mutations in the TSC1 or TSC2 genes, which encode a protein complex that inhibits mTOR kinase signaling by inactivating the Rheb GTPase. Activation of mTOR promotes the formation of benign tumors in various organs and the mechanisms underlying the neurological symptoms of the disease remain largely unknown. We found that Tsc2 haploinsufficiency in mice caused aberrant retinogeniculate projections that suggest defects in EphA receptor-dependent axon guidance. We also found that EphA receptor activation by ephrin-A ligands in neurons led to inhibition of extracellular signal-regulated kinase 1/2 (ERK1/2) activity and decreased inhibition of Tsc2 by ERK1/2. Thus, ephrin stimulation inactivates the mTOR pathway by enhancing Tsc2 activity. Furthermore, Tsc2 deficiency and hyperactive Rheb constitutively activated mTOR and inhibited ephrin-induced growth cone collapse. Our results indicate that TSC2-Rheb-mTOR signaling cooperates with the ephrin-Eph receptor system to control axon guidance in the visual system.
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PMID:Tsc2-Rheb signaling regulates EphA-mediated axon guidance. 2006 52

Pulmonary lymphangioleiomyomatosis (LAM) is a rare genetic disease characterized by neoplastic growth of atypical smooth muscle-like LAM cells, destruction of lung parenchyma, obstruction of lymphatics, and formation of lung cysts, leading to spontaneous pneumothoraces (lung rupture and collapse) and progressive loss of pulmonary function. The disease is caused by mutational inactivation of the tumor suppressor gene tuberous sclerosis complex 1 (TSC1) or TSC2. By injecting TSC2-null cells into nude mice, we have developed a mouse model of LAM that is characterized by multiple random TSC2-null lung lesions, vascular endothelial growth factor-D expression, lymphangiogenesis, destruction of lung parenchyma, and decreased survival, similar to human LAM. The mice show enlargement of alveolar airspaces that is associated with progressive growth of TSC2-null lesions in the lung, up-regulation of proinflammatory cytokines and matrix metalloproteinases (MMPs) that degrade extracellular matrix, and destruction of elastic fibers. TSC2-null lesions and alveolar destruction were differentially inhibited by the macrolide antibiotic rapamycin (which inhibits TSC2-null lesion growth by a cytostatic mechanism) and a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, simvastatin (which inhibits growth of TSC2-null lesions by a predominantly proapoptotic mechanism). Treatment with simvastatin markedly inhibited MMP-2, MMP-3, and MMP-9 levels in lung and prevented alveolar destruction. The combination of rapamycin and simvastatin prevented both growth of TSC2-null lesions and lung destruction by inhibiting MMP-2, MMP-3, and MMP-9. Our findings demonstrate a mechanistic link between loss of TSC2 and alveolar destruction and suggest that treatment with rapamycin and simvastatin together could benefit patients with LAM by targeting cells with TSC2 dysfunction and preventing airspace enlargement.
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PMID:Prevention of alveolar destruction and airspace enlargement in a mouse model of pulmonary lymphangioleiomyomatosis (LAM). 2303 46

Cardiac rhabdomyoma (CR) is a rare tumor commonly associated with tuberous sclerosis. They are often detected prenatally or in early infancy. The case of a Nigerian human immunodeficiency virus (HIV)-exposed neonate with CR who presented with supraventricular tachycardia and cardiovascular collapse is presented. The infant was born to a mother on highly active antiretroviral therapy (HAART). The possible role of HIV and HAART in CR etiology and the difficulty in the management of this case are highlighted.
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PMID:Cardiac rhabdomyoma in a neonate with supraventricular tachycardia. 2440 67

Background: Hemorrhage from an angiomyolipoma (AML) of the kidney can be life threatening and arterial embolization is the primary treatment. Embolization is less invasive than surgery, is well tolerated, and major complications are rare. We describe a case of disseminated intravascular coagulation (DIC) after embolization of a bleeding renal AML in a 44-year-old man with massive bilateral AMLs. This report aims to highlight the possibility that acute DIC could be a major complication of embolization itself and so should be considered and screened for because, if present, it requires early and aggressive management. Case Presentation: A 44-year-old man with a history of large bilateral renal AMLs associated with tuberous sclerosis complex presented with visible hematuria and abdominal pain. Renal CT revealed bleeding from the right kidney. Embolization with polyvinyl alcohol and lipiodol was urgently performed. The following day he required multiple blood transfusions and repeat embolization, this time with gelfoam and "tornado" coils. He suddenly developed DIC, cardiovascular collapse and acute renal failure requiring many days in the intensive care unit for inotropic support and renal replacement therapy. Conclusion: Arterial embolization may be associated with increased risk of DIC in the setting of treating large bleeding renal AMLs. DIC may be a direct or indirect complication of this. The clinician must act quickly to identify this and treat this complication aggressively.
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PMID:Disseminated Intravascular Coagulation After Embolization to Treat Acutely Bleeding Bilateral Massive Angiomyolipoma: A Case Report. 3006 60

Rhabdomyomas are histologically benign tumors known to be associated with tuberous sclerosis. The natural history predicts the majority of tumors to be asymptomatic and regress within the first year of life. We describe a neonate presenting on day 1 of life with cardiovascular collapse secondary to a massive rhabdomyoma. Surgical resection was excluded due to the extensive nature of the lesion and oral sirolimus, a mammalian target of rapamycin inhibitor, was commenced to promote tumor regression. The patient developed intractable arrhythmias requiring extracorporeal life support during therapy.
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PMID:Innovative Strategies for the Management of a Massive Neonatal Rhabdomyoma. 3107 77