Emicizumab for the treatment of acquired hemophilia A: Retrospective review of a single-institution experience.

Introduction: Acquired haemophilia A (AHA) is a rare and potentially life-threatening bleeding disorder arising from autoantibodies that inhibit coagulation factor VIII (FVIII). Treatment entails achieving haemostasis with bypassing agents or factor replacement, and eradication of the inhibitor with immunosuppressive therapy (IST). Due to the rarity of AHA, there are few prospective data to guide management.

Dysregulated myosin in Hermansky-Pudlak syndrome lung fibroblasts is associated with increased cell motility.

Hermansky-Pudlak syndrome (HPS) is an autosomal recessive disorder characterized by improper biogenesis of lysosome-related organelles (LROs). Lung fibrosis is the leading cause of death among adults with HPS-1 and HPS-4 genetic types, which are associated with defects in the biogenesis of lysosome-related organelles complex-3 (BLOC-3), a guanine exchange factor (GEF) for a small GTPase, Rab32. LROs are not ubiquitously present in all cell types, and specific cells utilize LROs to accomplish dedicated functions.

Pulmonary Vasculopathy Associated with FIGF Gene Mutation.

Vascular endothelial growth factor (VEGF)-D is capable of inducing angiogenesis and lymphangiogenesis through signaling via VEGF receptor (VEGFR)-2 and VEGFR-3, respectively. Mutations in the FIGF (c-fos-induced growth factor) gene encoding VEGF-D have not been reported previously. We describe a young male with a hemizygous mutation in the X-chromosome gene FIGF (c.

The History of Antithrombotic Therapy: The Discovery of Heparin, the Vitamin K Antagonists, and the Utility of Aspirin.

The administration of intravenous heparin to postoperative patients by Barritt and Jordan reduced the incidence of fatal and nonfatal pulmonary embolism and established heparin as the standard for parenteral anticoagulation. The coumarin family of vitamin K antagonists quickly became the standard for long-term oral anticoagulation. Aspirin became a widely used antithrombotic agent after the discovery that chronic oral administration reduced the incidence of secondary strokes and myocardial infarction.

A clinically relevant in vivo zebrafish model of human multiple myeloma to study preclinical therapeutic efficacy.

Patient-derived multiple myeloma (MM) cells are difficult to establish in culture or propagate in vivo in murine model. Here, we describe a zebrafish xenograft model that permits rapid, reliable growth of human MM cells injected into the perivitelline space of albino zebrafish (Casper) embryos 48 hours postfertilization. MM1S and MM1R MM cell lines and primary CD138(+) MM cells were stained with CM-Dil red fluorescent dye and suspended in Matrigel prior to their injection.

Cancer Cell Dissemination and Homing to the Bone Marrow in a Zebrafish Model.

Advancement of many solid tumors and hematologic malignancies is frequently characterized by dissemination and homing of cancer cells to the bone marrow (BM). Methods to quantitatively characterize these key steps of the metastatic cascade in mammalian models are currently limited and do not offer opportunities to perform rapid, large-scale genomic, or drug screening. Because of their optical clarity, we used zebrafish to develop an in vivo model of cancer cell dissemination and homing to the BM.

The identification and characterization of zebrafish hematopoietic stem cells.

HSCs are defined by their ability to self-renew and maintain hematopoiesis throughout the lifespan of an organism. The optical clarity of their embryos and the ease of genetic manipulation make the zebrafish (Danio rerio) an excellent model for studying hematopoiesis. Using flow cytometry, we identified 2 populations of CD41-GFP(+) cells (GFP(hi) and GFP(lo)) in the whole kidney marrow of Tg(CD41:GFP) zebrafish.

Identification of adult nephron progenitors capable of kidney regeneration in zebrafish.

Loss of kidney function underlies many renal diseases. Mammals can partly repair their nephrons (the functional units of the kidney), but cannot form new ones. By contrast, fish add nephrons throughout their lifespan and regenerate nephrons de novo after injury, providing a model for understanding how mammalian renal regeneration may be therapeutically activated.

PDGF signaling is required for epicardial function and blood vessel formation in regenerating zebrafish hearts.

A zebrafish heart can fully regenerate after amputation of up to 20% of its ventricle. During this process, newly formed coronary blood vessels revascularize the regenerating tissue. The formation of coronary blood vessels during zebrafish heart regeneration likely recapitulates embryonic coronary vessel development, which involves the activation and proliferation of the epicardium, followed by an epithelial-to-mesenchymal transition.

The role and regulation of friend of GATA-1 (FOG-1) during blood development in the zebrafish.

The nuclear protein FOG-1 binds transcription factor GATA-1 to facilitate erythroid and megakaryocytic maturation. However, little is known about the function of FOG-1 during myeloid and lymphoid development or how FOG-1 expression is regulated in any tissue. We used in situ hybridization, gain- and loss-of-function studies in zebrafish to address these problems.

The zebrafish vitronectin receptor: characterization of integrin alphaV and beta3 expression patterns in early vertebrate development.

alphaVbeta3 is a receptor for vitronectin and other extracellular matrix ligands, and it has been implicated in angiogenesis and osteoclast function in mammals. We have cloned full-length cDNAs of zebrafish integrin alphaV (itgalphaV), and two paralogous zebrafish beta3 integrins (itgbeta3.1 and itgbeta3.

Functional conservation of erythropoietin signaling in zebrafish.

Erythropoietin (Epo) and its cognate receptor (EpoR) are required for maintaining adequate levels of circulating erythrocytes during embryogenesis and adulthood. Here, we report the functional characterization of the zebrafish epo and epor genes. The expression of epo and epor was evaluated by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) and whole-mount in situ hybridization, revealing marked parallels between zebrafish and mammalian gene expression patterns.

Tracing hematopoietic precursor migration to successive hematopoietic organs during zebrafish development.

Although the ontogeny of hematopoietic stem cells (HSCs) in vertebrates has been studied intensely, a lineage relationship between the HSCs found in the developmentally successive hematopoietic organs remains to be shown. By using an in situ photoactivatable cell tracer in the transparent zebrafish embryo, we demonstrated that definitive blood precursors appeared between the dorsal aorta and axial vein, validating the homology of this tissue with the AGM (aorta-gonad-mesonephros) of amniotes. These cells first migrated through the blood to a previously undescribed caudal hematopoietic tissue (CHT), where they differentiated, expanded, and further migrated to seed the definitive hematopoietic organs, the thymus and kidney.

Inherited platelet disorders.

The inherited platelet disorders are a heterogeneous collection of rare diseases that are infrequently encountered in clinical practice. They are, however, fascinating abnormalities, which have taught us a great deal about normal platelet biochemistry and physiology. In this section of the presentation we will review disorders of the platelet membrane, platelet granule packaging disorders, the hereditary macrothrombocytopenias, platelet signaling disorders and disorders of platelet coagulant function.

Analysis of thrombocyte development in CD41-GFP transgenic zebrafish.

Thrombocytes are the nucleated equivalent of platelets in nonmammalian vertebrates such as the zebrafish, Danio rerio. We have cloned zebrafish CD41 cDNA (alpha(IIb), glycoprotein IIb [GPIIb]) and its promoter and have generated transgenic zebrafish lines with green fluorescent protein (GFP)-tagged thrombocytes. CD41 mRNA transcripts appeared 42 hours after fertilization (hpf) by reverse-transcriptase-polymerase chain reaction (RT-PCR) and at 48 hpf in circulating hematopoietic cells.

An initiative in mentoring to promote residents' and faculty members' careers.

Internal medicine trainees and faculty recognize the value of effective mentoring to help meet the personal and professional needs of residents. However, the paradigm of the mentor-trainee relationship is seriously threatened by increased clinical, research, and administrative demands on both faculty and housestaff. Moreover, the current criteria for promotion in most teaching hospitals emphasize scholarship, rather than citizenship, so activities such as mentoring devolve to a lower priority.

Mapping the glycoprotein Ib-binding site in the von willebrand factor A1 domain.

The von Willebrand factor (vWF) mediates platelet adhesion to exposed subendothelium at sites of vascular injury. It does this by forming a bridge between subendothelial collagen and the platelet glycoprotein Ib-IX-V complex (GPIb). The GPIb-binding site within vWF has been localized to the vWF-A1 domain.

Crystal structure of the von Willebrand Factor A1 domain and implications for the binding of platelet glycoprotein Ib.

von Willebrand Factor (vWF) is a multimeric protein that mediates platelet adhesion to exposed subendothelium at sites of vascular injury under conditions of high flow/shear. The A1 domain of vWF (vWF-A1) forms the principal binding site for platelet glycoprotein Ib (GpIb), an interaction that is tightly regulated. We report here the crystal structure of the vWF-A1 domain at 2.

The von willebrand factor A3 domain does not contain a metal ion-dependent adhesion site motif.

von Willebrand factor (vWF) is a multimeric plasma protein that mediates platelet adhesion to exposed subendothelium at sites of vascular injury. The A3 domain of vWF (vWF-A3) forms the principal binding site for collagens type I and III. We report here the crystal structure of the vWF-A3 domain at 2.