Genomic stability in response to high versus low linear energy transfer radiation in Arabidopsis thaliana.

Low linear energy transfer (LET) gamma rays and high LET HZE (high atomic weight, high energy) particles act as powerful mutagens in both plants and animals. DNA damage generated by HZE particles is more densely clustered than that generated by gamma rays. To understand the genetic requirements for resistance to high versus low LET radiation, a series of Arabidopsis thaliana mutants were exposed to either 1GeV Fe nuclei or gamma radiation. A comparison of effects on the germination and subsequent growth of seedlings led us to conclude that the relative biological effectiveness (RBE) of the two types of radiation (HZE versus gamma) are roughly 3:1. Similarly, in wild-type lines, loss of somatic heterozygosity was induced at an RBE of about a 2:1 (HZE versus gamma). Checkpoint and repair defects, as expected, enhanced sensitivity to both agents. The "replication fork" checkpoint, governed by ATR, played a slightly more important role in resistance to HZE-induced mutagenesis than in resistance to gamma induced mutagenesis

The Impact of the COVID-19 Pandemic on Consumer Bankruptcies

This manuscript conducts a simple, exploratory analysis to test whether the use of the consumer bankruptcy process fundamentally differed during the COVID-19 pandemic compared to previous years. Data were drawn from the Public Access to Court Electronic Records (PACER) database maintained by the U.S. Bankruptcy Court’s Eastern District of Washington for the years 2007, 2011, 2016, and 2020. KruskalWallis tests indicate that filers in 2020 had lower average real monthly incomes than in previous years. However, household incomes were not statistically different from previous years. Filers in 2020 has significantly more debt in collections compared to 2007, but no more or less debt than in 2011 or 2016. Chi-square tests report a significantly greater proportion of filings with debts owed to collections agencies in 2020 compared to previous years. Overall, the findings suggest that the pandemic did significantly alter the use, and intensity of use, of the consumer bankruptcy process

On the Relationship Between Asset Exemptions and Outstanding Tax Repayments in Chapter 7 Bankruptcy

Under a Chapter 7 bankruptcy filing, assets are liquidated and used to repay debts, in order of a Court-established priority. If not repaid through the liquidation process, some of these debts (especially certain types of unpaid taxes) survive the bankruptcy proceedings and must still be repaid. The U.S. Bankruptcy Code allows individuals filing under Chapter 7 to exempt certain assets from the liquidation process. More generous exemptions lead to a lower value of assets liquidated and used to repay creditors. This leads to an interesting decision problem. Do filers with exempt assets and tax debts choose to retain their exempt assets and allow the tax obligations to survive the bankruptcy process? Or do they use the liquidation process to reduce outstanding tax obligations? This manuscript empirically explores this issue. We find no statistically significant evidence suggesting that households with greater exempt assets accumulate or repay a greater proportion of tax debts. However, filers who own businesses are more likely to accumulate and repay tax debts through bankruptcy

Impact of COVID-19 Pandemic on Pharmacy Teaching at a Midwestern University

The coronavirus (COVID-19) pandemic severely impacted higher education institutions. In March 2020, the North Dakota State University School of Pharmacy notified faculty and students that the remainder of the semester would be taught using remote learning. The study objective is to determine how the change from the traditional classroom to remote learning impacted students and faculty. Pharmacy students were surveyed to ascertain how the transition to remote learning have impacted their learning. Additionally, faculty were surveyed using a semi-structured interview to assess their instructional efforts. The student survey findings identify several challenges impacting instruction, including online exam-taking and balancing time constraints. Faculty survey responses collected include themes of decreased student engagement, technology use and access, and transitions in the learning environment. Curriculum areas facing significant challenges during the pandemic include hands-on laboratory skills and experiential education which required multiple changes. Despite the challenges, faculty made the teaching transitions that they might not have otherwise tried. Assessing the impact of remote learning will continue to be important as the pandemic continues

Telomere dynamics and fusion of critically shortened telomeres in plants lacking DNA ligase IV

In the absence of the telomerase, telomeres undergo progressive shortening and are ultimately recruited into end-to-end chromosome fusions via the non-homologous end joining (NHEJ) double-strand break repair pathway. Previously, we showed that fusion of critically shortened telomeres in Arabidopsis proceeds with approximately the same efficiency in the presence or absence of KU70, a key component of NHEJ. Here we report that DNA ligase IV (LIG4) is also not essential for telomere joining. We observed only a modest decrease (3-fold) in the frequency of chromosome fusions in triple tert ku70 lig4 mutants versus tert ku70 or tert. Sequence analysis revealed that, relative to tert ku70, chromosome fusion junctions in tert ku70 lig4 mutants contained less microhomology and less telomeric DNA. These findings argue that the KU-LIG4 independent end-joining pathway is less efficient and mechanistically distinct from KU-independent NHEJ. Strikingly, in all the genetic backgrounds we tested, chromosome fusions are initiated when the shortest telomere in the population reaches ∼1 kb, implying that this size represents a critical threshold that heralds a detrimental structural transition. These data reveal the transitory nature of telomere stability, and the robust and flexible nature of DNA repair mechanisms elicited by telomere dysfunction

Drug hypersensitivity caused by alteration of the MHC-presented self-peptide repertoire

Idiosyncratic adverse drug reactions are unpredictable, dose independent and potentially life threatening; this makes them a major factor contributing to the cost and uncertainty of drug development. Clinical data suggest that many such reactions involve immune mechanisms, and genetic association studies have identified strong linkage between drug hypersensitivity reactions to several drugs and specific HLA alleles. One of the strongest such genetic associations found has been for the antiviral drug abacavir, which causes severe adverse reactions exclusively in patients expressing the HLA molecular variant B*57:01. Abacavir adverse reactions were recently shown to be driven by drug-specific activation of cytokine-producing, cytotoxic CD8+ T cells that required HLA-B*57:01 molecules for their function. However, the mechanism by which abacavir induces this pathologic T cell response remains unclear. Here we show that abacavir can bind within the F-pocket of the peptide-binding groove of HLA-B*57:01 thereby altering its specificity. This supports a novel explanation for HLA-linked idiosyncratic adverse drug reactions; namely that drugs can alter the repertoire of self-peptides presented to T cells thus causing the equivalent of an alloreactive T cell response. Indeed, we identified specific self-peptides that are presented only in the presence of abacavir, and that were recognized by T cells of hypersensitive patients. The assays we have established can be applied to test additional compounds with suspected HLA linked hypersensitivities in vitro. Where successful, these assays could speed up the discovery and mechanistic understanding of HLA linked hypersensitivities as well as guide the development of safer drugs

Structure based inhibitor design targeting glycogen phosphorylase b. Virtual screening, synthesis, biochemical and biological assessment of novel N-acyl-β-d-glucopyranosylamines

Glycogen phosphorylase (GP) is a validated target for the development of new type 2 diabetes treatments. Exploiting the Zinc docking database, we report the in silico screening of 1888 β- D-glucopyranose-NH-CO-R putative GP inhibitors differing only in their R groups. CombiGlide and GOLD docking programs with different scoring functions were employed with the best performing methods combined in a “consensus scoring” approach to ranking of ligand binding affinities for the active site. Six selected candidates from the screening were then synthesized and their inhibitory potency was assessed both in vitro and ex vivo. Their inhibition constants’ values, in vitro, ranged from 5 to 377 µM while two of them were effective at causing inactivation of GP in rat hepatocytes at low µM concentrations. The crystal structures of GP in complex with the inhibitors were defined and provided the structural basis for their inhibitory potency and data for further structure based design of more potent inhibitors

Unveiling the "Three Finger Pharmacophore" required for p53-MDM2 Inhibition by Saturation Transfer Difference NMR Initial Growth Rates Approach

Inhibitors of the p53-MDM2 protein-protein interaction are emerging as a novel and validated approach to treating cancer. In this work we describe the synthesis and inhibitory evaluation of a series of isoquinolin-1-one analogues, and highlight the utility of an initial growth rates STD NMR approach supported by protein-ligand docking to investigate p53-MDM2 inhibition. The approach is illustrated by the study of compound 1, providing key insights into the binding mode of this kind of MDM2 ligands and, more importantly, readily unveiling the previously proposed three finger pharmacophore requirement for p53-MDM2 inhibition