Design and Development of a Dynamically Deforming Leading Edge Airfoil for Unsteady Flow Control

ICIASF '97 RECORD, IEEE Publication No. 97CH36121, pp. 132-140.A novel approach to unsteady flow separation and dynamic stall control using a dynamically deforming leading edge airfoil is described. The design details of a carbon-fiber composite skin airfoil having a thickness of 0.002 in. at the leading edge and capable of deforming at 20 Hz in unsteady flow at freestream Mach numbers of up to 0.45, are discussed. Implementation of the scheme at model scales places extraordinary demands on the design, material and fabrication of such an airfoil. Rate scaling further requires very-rapid-response instrumental ion, measurement techniques and data acquisition schemes. The special instrumentation control system developed for these experiments as well as the fluid dynamic results of successful flow control that was achieved using this method, are also discussed.U.S. Army Research Office ARO MIPR 133-94, ARO 32480.11-EGU.S. Army Research Office ARO MIPR 133-94, ARO 32480.11-E

ALK1 controls hepatic vessel formation, angiodiversity, and angiocrine functions in hereditary hemorrhagic telangiectasia of the liver

Background and Aims In hereditary hemorrhagic telangiectasia (HHT), severe liver vascular malformations are associated with mutations in the Activin A Receptor-Like Type 1 (ACVRL1) gene encoding ALK1, the receptor for bone morphogenetic protein (BMP) 9/BMP10, which regulates blood vessel development. Here, we established an HHT mouse model with exclusive liver involvement and adequate life expectancy to investigate ALK1 signaling in liver vessel formation and metabolic function. Approach and Results Liver sinusoidal endothelial cell (LSEC)-selective Cre deleter line, Stab2-iCreF3, was crossed with Acvrl1-floxed mice to generate LSEC-specific Acvrl1-deficient mice (Alk1(HEC-KO)). Alk1(HEC-KO) mice revealed hepatic vascular malformations and increased posthepatic flow, causing right ventricular volume overload. Transcriptomic analyses demonstrated induction of proangiogenic/tip cell gene sets and arterialization of hepatic vessels at the expense of LSEC and central venous identities. Loss of LSEC angiokines Wnt2, Wnt9b, and R-spondin-3 (Rspo3) led to disruption of metabolic liver zonation in Alk1(HEC-KO) mice and in liver specimens of patients with HHT. Furthermore, prion-like protein doppel (Prnd) and placental growth factor (Pgf) were upregulated in Alk1(HEC-KO) hepatic endothelial cells, representing candidates driving the organ-specific pathogenesis of HHT. In LSEC in vitro, stimulation or inhibition of ALK1 signaling counter-regulated Inhibitors of DNA binding (ID)1-3, known Alk1 transcriptional targets. Stimulation of ALK1 signaling and inhibition of ID1-3 function confirmed regulation of Wnt2 and Rspo3 by the BMP9/ALK1/ID axis. Conclusions Hepatic endothelial ALK1 signaling protects from development of vascular malformations preserving organ-specific endothelial differentiation and angiocrine signaling. The long-term surviving Alk1(HEC-KO) HHT model offers opportunities to develop targeted therapies for this severe disease.Cancer Signaling networks and Molecular Therapeutic

ALK1 controls hepatic vessel formation, angiodiversity, and angiocrine functions in hereditary hemorrhagic telangiectasia of the liver

Background and Aims In hereditary hemorrhagic telangiectasia (HHT), severe liver vascular malformations are associated with mutations in the Activin A Receptor-Like Type 1 (ACVRL1) gene encoding ALK1, the receptor for bone morphogenetic protein (BMP) 9/BMP10, which regulates blood vessel development. Here, we established an HHT mouse model with exclusive liver involvement and adequate life expectancy to investigate ALK1 signaling in liver vessel formation and metabolic function. Approach and Results Liver sinusoidal endothelial cell (LSEC)-selective Cre deleter line, Stab2-iCreF3, was crossed with Acvrl1-floxed mice to generate LSEC-specific Acvrl1-deficient mice (Alk1(HEC-KO)). Alk1(HEC-KO) mice revealed hepatic vascular malformations and increased posthepatic flow, causing right ventricular volume overload. Transcriptomic analyses demonstrated induction of proangiogenic/tip cell gene sets and arterialization of hepatic vessels at the expense of LSEC and central venous identities. Loss of LSEC angiokines Wnt2, Wnt9b, and R-spondin-3 (Rspo3) led to disruption of metabolic liver zonation in Alk1(HEC-KO) mice and in liver specimens of patients with HHT. Furthermore, prion-like protein doppel (Prnd) and placental growth factor (Pgf) were upregulated in Alk1(HEC-KO) hepatic endothelial cells, representing candidates driving the organ-specific pathogenesis of HHT. In LSEC in vitro, stimulation or inhibition of ALK1 signaling counter-regulated Inhibitors of DNA binding (ID)1-3, known Alk1 transcriptional targets. Stimulation of ALK1 signaling and inhibition of ID1-3 function confirmed regulation of Wnt2 and Rspo3 by the BMP9/ALK1/ID axis. Conclusions Hepatic endothelial ALK1 signaling protects from development of vascular malformations preserving organ-specific endothelial differentiation and angiocrine signaling. The long-term surviving Alk1(HEC-KO) HHT model offers opportunities to develop targeted therapies for this severe disease