Mapping genotypes to chromatin accessibility profiles in single cells.

In somatic tissue differentiation, chromatin accessibility changes govern priming and precursor commitment towards cellular fates1-3. Therefore, somatic mutations are likely to alter chromatin accessibility patterns, as they disrupt differentiation topologies leading to abnormal clonal outgrowth. However, defining the impact of somatic mutations on the epigenome in human samples is challenging due to admixed mutated and wild-type cells. Here, to chart how somatic mutations disrupt epigenetic landscapes in human clonal outgrowths, we developed genotyping of targeted loci with single-cell chromatin accessibility (GoT-ChA). This high-throughput platform links genotypes to chromatin accessibility at single-cell resolution across thousands of cells within a single assay. We applied GoT-ChA to CD34+ cells from patients with myeloproliferative neoplasms with JAK2V617F-mutated haematopoiesis. Differential accessibility analysis between wild-type and JAK2V617F-mutant progenitors revealed both cell-intrinsic and cell-state-specific shifts within mutant haematopoietic precursors, including cell-intrinsic pro-inflammatory signatures in haematopoietic stem cells, and a distinct profibrotic inflammatory chromatin landscape in megakaryocytic progenitors. Integration of mitochondrial genome profiling and cell-surface protein expression measurement allowed expansion of genotyping onto DOGMA-seq through imputation, enabling single-cell capture of genotypes, chromatin accessibility, RNA expression and cell-surface protein expression. Collectively, we show that the JAK2V617F mutation leads to epigenetic rewiring in a cell-intrinsic and cell type-specific manner, influencing inflammation states and differentiation trajectories. We envision that GoT-ChA will empower broad future investigations of the critical link between somatic mutations and epigenetic alterations across clonal populations in malignant and non-malignant contexts.

Extensive Intracardiac and Deep Venous Thromboses in a Young Woman with Heparin-Induced Thrombocytopenia and May-Thurner Syndrome.

A 38-year-old woman with a history of recurrent deep venous thromboses (DVTs) on chronic anticoagulation presented with acute left leg swelling. The patient was diagnosed with an acute left lower extremity (LLE) DVT in the setting of May-Thurner syndrome for which treatment with unfractionated heparin was started. Her hospital course was complicated by a new diagnosis of heparin-induced thrombocytopenia (HIT), with an incidental discovery of a large tricuspid valve mobile mass on a transthoracic echocardiogram (TTE). Subsequent imaging confirmed multiple right atrial thrombi along with LLE venous stent thrombosis and a new right LE acute DVT. Anticoagulation with argatroban for HIT thrombosis was started. She underwent a right atrial percutaneous thrombectomy and bilateral lower extremity thrombectomy with directed angioplasty and stent placement. This presentation is a rare manifestation of HIT with extensive intracardiac and deep venous thrombi, with successful staged interventions.

A fluoride-derived electrophilic late-stage fluorination reagent for PET imaging.

The unnatural isotope fluorine-18 ((18)F) is used as a positron emitter in molecular imaging. Currently, many potentially useful (18)F-labeled probe molecules are inaccessible for imaging because no fluorination chemistry is available to make them. The 110-minute half-life of (18)F requires rapid syntheses for which [(18)F]fluoride is the preferred source of fluorine because of its practical access and suitable isotope enrichment. However, conventional [(18)F]fluoride chemistry has been limited to nucleophilic fluorination reactions. We report the development of a palladium-based electrophilic fluorination reagent derived from fluoride and its application to the synthesis of aromatic (18)F-labeled molecules via late-stage fluorination. Late-stage fluorination enables the synthesis of conventionally unavailable positron emission tomography (PET) tracers for anticipated applications in pharmaceutical development as well as preclinical and clinical PET imaging.

Insertion of the Impella 5.0 left ventricular assist device via right anterior mini-thoracotomy: a novel practical approach.

The Impella 5.0 microaxial pump is a miniaturized left ventricular assist device commonly used for circulatory support in acute cardiogenic shock. The catheter-based pump is designed to be inserted either into a peripheral artery or directly into the ascending aorta. We report the first case in which the Impella 5.0 device was placed directly into the ascending aorta via a small right anterior thoracotomy in a patient following acute myocardial infarction complicated by cardiogenic shock.