Nf1 haploinsufficiency alters myeloid lineage commitment and function, leading to deranged skeletal homeostasis

Although nullizygous loss of NF1 leads to myeloid malignancies, haploinsufficient loss of NF1 (Nf1) has been shown to contribute to osteopenia and osteoporosis which occurs in approximately 50% of neurofibromatosis type 1 (NF1) patients. Bone marrow mononuclear cells of haploinsufficient NF1 patients and Nf1(+/-) mice exhibit increased osteoclastogenesis and accelerated bone turnover; however, the culprit hematopoietic lineages responsible for perpetuating these osteolytic manifestations have yet to be elucidated. Here we demonstrate that conditional inactivation of a single Nf1 allele within the myeloid progenitor cell population (Nf1-LysM) is necessary and sufficient to promote multiple osteoclast gains-in-function, resulting in enhanced osteoclastogenesis and accelerated osteoclast bone lytic activity in response to proresorptive challenge in vivo. Surprisingly, mice conditionally Nf1 heterozygous in mature, terminally differentiated osteoclasts (Nf1-Ctsk) do not exhibit any of these skeletal phenotypes, indicating a critical requirement for Nf1 haploinsufficiency at a more primitive/progenitor stage of myeloid development in perpetuating osteolytic activity. We further identified p21Ras-dependent hyperphosphorylation of Pu.1 within the nucleus of Nf1 haploinsufficient myelomonocytic osteoclast precursors, providing a novel therapeutic target for the potential treatment of NF1 associated osteolytic manifestations

Microfluidic Approaches to Thrombosis and Hemostasis: Towards a Patient-Specific Test of Antiplatelet Therapeutics and the Assessment of Coagulopathy in Hemophilic and Trauma Patients

Current in vitro or ex vivo models of hemostasis and thrombosis fail to recapitulate the hemodynamic conditions and biorheologic phenomena found throughout the vasculature. Microfluidic technology enables physiologic hemodynamics for the study of platelet deposition and coagulation using minimum volumes of human whole blood. This dissertation describes the application of microfluidic assays, the manipulation of surface-patterned procoagulant and sub-endothelial proteins, anti-coagulation, and flow conditions to investigate platelet function and coagulation under flow. First, we demonstrate a novel method to assess the in vivo or in vitro therapeutic efficacy of anti-platelet therapies on platelet aggregates adhering to collagen type I surfaces. We phenotyped individual healthy donor platelet function responses to in vivo or in vitro aspirin, a common antiplatelet therapy over collagen type I surfaces at venous shear rates. Utilizing the same flow assay, we also characterized mechanism-based resistance to aspirin conferred by non-steroidal anti-inflammatory drugs. Furthermore, we have also developed a new model to assess the intrinsic pathway of coagulation under flow on collagen type I surfaces and investigated the role of the intrinsic pathway in recombinant coagulation factor VIIa (rFVIIa) therapeutic efficacy. We then extended this mechanistic investigation of rFVIIa to flow assays where clotting is initiated by collagen and immobilized lipidated tissue factor to evaluate the role of the intrinsic tenase in conjunction with exogenous rFVIIa when surface-triggered extrinsic pathway is present. Finally, we continued to assess coagulopathic patients by first mimicking resuscitation-driven hemodilution, hyperfibrinolysis, and plasmin-inhibitor therapy under flow. We then evaluated downregulation of platelet function in whole blood from trauma patients during the acute phase of trauma-induced coagulopathy. The development of microfluidics, microfabrication, and its applications in hemostasis and thrombosis is essential in advancing our knowledge of clinical and pathological disorders such as myocardial infracts, hemophilia, and deep vein thrombosis. Beyond this work, microfluidic platforms in hemostasis and thrombosis can potentially be used as drug screening platforms for antiplatelet or clotting factor therapies, or a point of care diagnostic test for bleeding and pin-pointing the therapeutic index of novel biopharmaceutics

Phosphorus-doped porous carbons as efficient electrocatalysts for oxygen reduction

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.Efficient electrocatalysts for the oxygen reduction reaction (ORR) play a critical role in the performance of fuel cells and metal–air batteries. In this study, we report a facile synthesis of phosphorus (P)-doped porous carbon as a highly active electrocatalyst for the ORR. Phosphorus-doped porous carbon was prepared by simultaneous doping and activation of carbon with phosphoric acid (H3PO4) in the presence of Co. Both phosphorus and cobalt were found to play significant roles in improving the catalytic activity of carbon for the ORR. The as-prepared phosphorus-doped porous carbon exhibited considerable catalytic activity for the ORR as evidenced by rotating ring-disk electrode studies. At the same mass loading, the Tafel slope of phosphorus-doped porous carbon electrocatalysts is comparable to that of the commercial Pt/C catalysts (20 wt% Pt on Vulcan XC-72, Johnson Matthey) with stability superior to Pt/C in alkaline solutions