Chemical Characterization of a Volatile Dubnium Compound, DbOCl3

The formation and the chemical characterization of single atoms of dubnium (Db, element 105), in the form of its volatile oxychloride, was investigated using the on-line gas phase chromatography technique, in the temperature range 350–600 °C. Under the exactly same chemical conditions, comparative studies with the lighter homologues of Group 5 in the Periodic Table clearly indicate the volatility sequence being NbOCl3 > TaOCl3 ≥ DbOCl3. From the obtained experimental results, thermochemical data for DbOCl3 were derived. The present study delivers reliable experimental information for theoretical calculations on chemical properties of transactinides

Thiopurine-mediated impairment of hematopoietic stem and leukemia cells in Nudt15R138C knock-in mice.

Thiopurines are widely used as antileukemia agents and immunosuppressants. Recent large-scale clinical studies revealed a strong association between the NUDT15 p.Arg139Cys (NUDT15R139C) polymorphism and severe thiopurine-induced leukocytopenia. We established knock-in mice harboring p.Arg138Cys (Nudt15R138C), which corresponds to the human polymorphism. A clinically relevant dose of mercaptopurine (MP) induced lethal cytopenia in Nudt15R138C-harboring mice. MP dose reduction attenuated the hematopoietic toxicity, phenocopying clinical observations and providing Nudt15 genotype-based tolerable doses of MP. High-dose MP induced acute damage to hematopoietic stem and progenitor cells (HSPCs) in Nudt15R138C/R138C mice. A competitive transplantation assay revealed that not only Nudt15R138C/R138C HSPCs, but also Nudt15+/R138C HSPCs suffered stronger damage than Nudt15+/+ HSPCs, even by lower-dose MP, after long-term administration. In a Nudt15 genotype-based posttransplantation leukemia recurrence model generated by bone marrow replacement with congenic wild-type cells and a small number of leukemia stem cells, MP prolonged the survival of mice with posttransplantation Nudt15R138C/R138C leukemia recurrence. In conclusion, our model will facilitate NUDT15 genotype-based precision medicine by providing safer estimates for MP dosing, and our findings highlighted the high susceptibility of hematopoietic stem cells to MP and suggested that exploiting thiopurine toxicity might be a novel treatment approach for leukemia in NUDT15R139C-harboring patients

FUS-ERG induces late-onset azacitidine resistance in acute myeloid leukaemia cells

Abstract FUS-ERG is a chimeric gene with a poor prognosis, found in myelodysplastic syndromes (MDS) and acute myeloid leukaemia (AML). It remains unclear whether DNA hypomethylating agents, including azacitidine (Aza), are effective in FUS-ERG-harbouring AML and how FUS-ERG induces chemoresistance. Stable Ba/F3 transfectants with FUS-ERG were repeatedly exposed to Aza for 7 days of treatment and at 21-day intervals to investigate Aza sensitivity. Stable FUS-ERG transfectants acquired resistance acquired resistance after three courses of Aza exposure. RNA sequencing (RNA-seq) was performed when Aza susceptibility began to change; genes with altered expression or transcript variants were identified. Molecular signatures of these genes were analysed using gene ontology. RNA-seq analyses identified 74 upregulated and 320 downregulated genes involved in cell motility, cytokine production, and kinase activity. Additionally, 1321 genes with altered transcript variants were identified, revealing their involvement in chromatin organisation. In a clinical case of AML with FUS-ERG, we compared whole-genome alterations between the initial MDS diagnosis and AML recurrence after Aza treatment. Genes with non-synonymous or near mutations in transcription regulatory areas (TRAs), additionally detected in AML recurrence, were collated with the gene list from RNA-seq to identify genes involved in acquiring Aza resistance in the presence of FUS-ERG. Whole-genome sequencing of clinical specimens identified 29 genes with non-synonymous mutations, including BCOR, and 48 genes located within 20 kb of 54 TRA mutations in AML recurrence. These genes were involved in chromatin organisation and included NCOR2 as an overlapping gene with RNA-seq data. Transcription regulators involved in mutated TRAs were skewed and included RCOR1 in AML recurrence. We tested the efficacy of BH3 mimetics, including venetoclax and S63845, in primary Aza-resistant AML cells treated with FUS-ERG. Primary FUS-ERG-harbouring AML cells acquiring Aza resistance affected the myeloid cell leukaemia-1 (MCL1) inhibitor S63845 but not while using venetoclax, despite no mutations in BCL2. FUS-ERG promoted Aza resistance after several treatments. The disturbance of chromatin organisation might induce this by co-repressors, including BCOR, NCOR2, and RCOR1. MCL1 inhibition could partially overcome Aza resistance in FUS-ERG-harbouring AML cells

Dynamic changes of mitral annulus in patients with degenerative mitral regurgitation and chronic atrial fibrillation undergoing mitral valve reconstruction.

Objective:This study was designed to assess structural and dynamic changes in the mitral annulus in patients before mitral valve reconstruction for degenerative mitral regurgitation with or without chronic atrial fibrillation.Methods:One hundred and fifty one consecutive patients undergoing mitral valve reconstruction for mitral regurgitation due to myxomatous disease between July 2013 and May 2016 were included. Of these, 117 had a sinus rhythm (SR group) and 34 had chronic AF (AF group). Patients who underwent aortic surgery and were found to have no underlying cardiac valve disease nor coronary artery disease were included as the control group (n = 20). Real-time three-dimensional trans-esophageal echocardiography (3D-TEE) was used to assess mitral annulus shape, size, and movements.Results:Annular areas in the control group were the smallest of the three groups and changed considerably through the cardiac cycle. Mean anteroposterior and intercommissural diameter measurements in the SR group were significantly larger but oscillated less than in the control group. Those diameters were the largest in the AF group and oscillated very little. Dilatation of the annulus in the AF and SR groups was accompanied by flattening and marked loss of oscillation in the height-to-intercommissural-width ratio which should peak in early systole.Conclusions:In patients with degenerative mitral regurgitation undergoing mitral valve surgery, preoperative chronic atrial fibrillation is associated with more progressed annular remodeling, characterized by marked enlargement of annular area, circumference, and anteroposterior diameter