Gambogic acid and juglone inhibit RNase P through distinct mechanisms.

The first step in transfer RNA (tRNA) maturation is the cleavage of the 5' end of precursor tRNA (pre-tRNA) catalyzed by ribonuclease P (RNase P). RNase P is either a ribonucleoprotein complex with a catalytic RNA subunit or a protein-only RNase P (PRORP). In most land plants, algae, and Euglenozoa, PRORP is a single-subunit enzyme. There are currently no inhibitors of PRORP for use as tools to study the biological function of this enzyme. Therefore, we screened for compounds that inhibit the activity of a model PRORP from A. thaliana organelles (PRORP1) using a high throughput fluorescence polarization cleavage assay. Two compounds, gambogic acid and juglone (5-hydroxy-1,4-naphthalenedione) that inhibit PRORP1 in the 1 µM range were identified and analyzed. We found these compounds similarly inhibit human mtRNase P, a multisubunit protein enzyme and are 50-fold less potent against bacterial RNA-dependent RNase P. Our biochemical measurements indicate that gambogic acid is a rapid-binding, uncompetitive inhibitor targeting the PRORP1-substrate complex, while juglone acts as a time-dependent PRORP1 inhibitor. Additionally, X-ray crystal structures of PRORP1 in complex with juglone demonstrate the formation of a covalent complex with cysteine side chains on the surface of the protein. Finally, we propose a model consistent with the kinetic data that involves juglone binding to PRORP1 rapidly to form an inactive enzyme-inhibitor complex and then undergoing a slow step to form an inactive covalent adduct with PRORP1. These inhibitors have the potential to be developed into tools to probe PRORP structure and function relationships.

Genomic Variation across a Clinical Cryptococcus Population Linked to Disease Outcome.

Cryptococcus neoformans is the causative agent of cryptococcosis, a disease with poor patient outcomes that accounts for approximately 180,000 deaths each year. Patient outcomes may be impacted by the underlying genetics of the infecting isolate; however, our current understanding of how genetic diversity contributes to clinical outcomes is limited. Here, we leverage clinical, in vitro growth and genomic data for 284 C. neoformans isolates to identify clinically relevant pathogen variants within a population of clinical isolates from patients with human immunodeficiency virus (HIV)-associated cryptococcosis in Malawi. Through a genome-wide association study (GWAS) approach, we identify variants associated with the fungal burden and the growth rate. We also find both small and large-scale variation, including aneuploidy, associated with alternate growth phenotypes, which may impact the course of infection. Genes impacted by these variants are involved in transcriptional regulation, signal transduction, glycosylation, sugar transport, and glycolysis. We show that growth within the central nervous system (CNS) is reliant upon glycolysis in an animal model and likely impacts patient mortality, as the CNS yeast burden likely modulates patient outcome. Additionally, we find that genes with roles in sugar transport are enriched in regions under selection in specific lineages of this clinical population. Further, we demonstrate that genomic variants in two genes identified by GWAS impact virulence in animal models. Our approach identifies links between the genetic variation in C. neoformans and clinically relevant phenotypes and animal model pathogenesis, thereby shedding light on specific survival mechanisms within the CNS and identifying the pathways involved in yeast persistence. IMPORTANCE Infection outcomes for cryptococcosis, most commonly caused by C. neoformans, are influenced by host immune responses as well as by host and pathogen genetics. Infecting yeast isolates are genetically diverse; however, we lack a deep understanding of how this diversity impacts patient outcomes. To better understand both clinical isolate diversity and how diversity contributes to infection outcomes, we utilize a large collection of clinical C. neoformans samples that were isolated from patients enrolled in a clinical trial across 3 hospitals in Malawi. By combining whole-genome sequence data, clinical data, and in vitro growth data, we utilize genome-wide association approaches to examine the genetic basis of virulence. Genes with significant associations display virulence attributes in both murine and rabbit models, demonstrating that our approach can identify potential links between genetic variants and patho-biologically significant phenotypes.

Safety and acceptability with the use of a contraceptive vaginal ring after surgical or medical abortion.

OBJECTIVE: The study was conducted to determine if a contraceptive vaginal ring (CVR) is a safe and acceptable method of contraception when used in the proximate postabortion period following first-trimester surgical or medical abortion. METHODS: A CVR was inserted within 1 week following a medical or surgical abortion. Participants were followed up for 3 months to determine safety and acceptability. Safety was measured by the absence of signs of infection or serious adverse events. Acceptability was assessed by the CVR satisfaction survey, completed at the 3-month follow-up visit. RESULTS: Of 81 participants enrolled in the study, 69 (85%) completed the first-month follow-up visit, and 54 (67%) completed the final 3-month follow-up visit. There were no serious adverse events and no signs of infection on physical exam. Most adverse events were mild and not specifically related to the CVR. Related adverse events were those commonly associated with hormonal contraception use. Eighty-nine percent of participants chose to continue the CVR as their birth control method. CONCLUSION: The CVR is potentially safe and has high acceptability when used in the proximate postabortion period following a first-trimester abortion.

Hemophagocytosis-Related (Asian Variant) Intravascular Large B-Cell Lymphoma in a Hispanic Patient: A Case Report Highlighting a Micronodular Pattern in the Spleen.

OBJECTIVES: We report a case of hemophagocytosis-related (Asian variant) intravascular large B-cell lymphoma (IVLBCL) in a patient of Western origin initially diagnosed by splenectomy with diffuse large B-cell lymphoma (DLBCL) with a micronodular pattern. The clonal relationship between these two DLBCL subtypes is also investigated. METHODS: Hemophagocytosis-related (Asian variant) IVLBCL was identified at autopsy in a 62-year-old Hispanic woman, in North America, following an antemortem diagnosis of massive splenic involvement by DLBCL with a micronodular pattern, a feature not expected of IVLBCL. RESULTS: These two apparently distinct lymphoma types demonstrated similar immunophenotypic profiles and IgH gene rearrangements of identical size suggesting a clonal relationship. The 2008 WHO classification system describes IVLBCL in the spleen as having a sinusoidal pattern. CONCLUSIONS: Our observations provide the first molecular genetic support for a seemingly underrecognized micronodular pattern of IVLBCL in the spleen and further support the proposal of a "mixed variant" of IVLBCL with concomitant "intravascular" and "solid" phases of disease.