32 research outputs found

    Metabolic glycan imaging by isonitrile-tetrazine click chemistry.

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    Seeing the sugar coating: N-Acetyl-glucosamine and mannosamine derivatives tagged with an isonitrile group are metabolically incorporated into cell-surface glycans and can be detected with a fluorescent tetrazine. This bioorthogonal isonitrile-tetrazine ligation is also orthogonal to the commonly used azide-cyclooctyne ligation, and so will allow simultaneous detection of the incorporation of two different sugars

    Evaluation of whole and core genome multilocus sequence typing allele schemes for Salmonella enterica outbreak detection in a national surveillance network, PulseNet USA

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    Salmonella enterica is a leading cause of bacterial foodborne and zoonotic illnesses in the United States. For this study, we applied four different whole genome sequencing (WGS)-based subtyping methods: high quality single-nucleotide polymorphism (hqSNP) analysis, whole genome multilocus sequence typing using either all loci [wgMLST (all loci)] and only chromosome-associated loci [wgMLST (chrom)], and core genome multilocus sequence typing (cgMLST) to a dataset of isolate sequences from 9 well-characterized Salmonella outbreaks. For each outbreak, we evaluated the genomic and epidemiologic concordance between hqSNP and allele-based methods. We first compared pairwise genomic differences using all four methods. We observed discrepancies in allele difference ranges when using wgMLST (all loci), likely caused by inflated genetic variation due to loci found on plasmids and/or other mobile genetic elements in the accessory genome. Therefore, we excluded wgMLST (all loci) results from any further comparisons in the study. Then, we created linear regression models and phylogenetic tanglegrams using the remaining three methods. K-means analysis using the silhouette method was applied to compare the ability of the three methods to partition outbreak and sporadic isolate sequences. Our results showed that pairwise hqSNP differences had high concordance with cgMLST and wgMLST (chrom) allele differences. The slopes of the regressions for hqSNP vs. allele pairwise differences were 0.58 (cgMLST) and 0.74 [wgMLST (chrom)], and the slope of the regression was 0.77 for cgMLST vs. wgMLST (chrom) pairwise differences. Tanglegrams showed high clustering concordance between methods using two statistical measures, the Baker’s gamma index (BGI) and cophenetic correlation coefficient (CCC), where 9/9 (100%) of outbreaks yielded BGI values ≥ 0.60 and CCCs were ≥ 0.97 across all nine outbreaks and all three methods. K-means analysis showed separation of outbreak and sporadic isolate groups with average silhouette widths ≥ 0.87 for outbreak groups and ≥ 0.16 for sporadic groups. This study demonstrates that Salmonella isolates clustered in concordance with epidemiologic data using three WGS-based subtyping methods and supports using cgMLST as the primary method for national surveillance of Salmonella outbreak clusters

    Recent Advances in the Classification and Treatment of Ependymomas

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    OPINION STATEMENT: Ependymomas are a subgroup of ependymal glia-derived neoplasms that affect children as well as adults. Arising within any CNS compartment, symptoms at presentation can range from acute onset due to increased intracranial pressure to insidious myelopathy. The overall survival (OS) outcomes in adult patients across the subgroups is heterogeneous with subependymoma having an excellent prognosis often even in the absence of any treatment, whereas supratentorial ependymomas tend to be higher grade in nature and may have an OS of 5 years despite gross total resection and adjuvant radiation. The rarity of ependymal tumors, together still only representing 1.8% of all primary CNS tumors, has been a long-standing challenge in defining optimal treatment guidelines via prospective randomized trials. Retrospective studies have supported maximal safe resection, ideally gross total resection, as the optimal treatment with adjuvant radiation therapy proffering additional tumor control. The evidence for efficacy of chemotherapy and targeted agents in adult ependymomas is minimal. Recent investigations of the molecular, genetic, and DNA methylation profiles of ependymal tumors across all age groups and CNS compartments have identified distinct oncogenic gene products as well as nine molecular subgroups correlating with similar outcomes. The 2016 World Health Organization of Tumors of the Central Nervous System update addresses some of these findings, although their clinical significance has not yet been fully validated. There are inconsistent survival outcomes in retrospective studies for ependymomas graded as II versus III, bringing into question the validity of histologic grading which is subject to high interobserver variability in part due to inconsistent application of mitotic count parameters

    The impact of mentoring on early career faculty: Assessment of a virtual mentoring program.

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    Background: Participation in mentorship programs for early career physicians may be crucial to developing key skills and professional networks to navigate racial, ethnic and gender leadership disparities in medicine. A 6-month virtual facilitated peer mentorship program was developed and piloted through the Society for Neuro-Oncology (SNO) Women & Diversity Committee. The evaluation of the program’s feasibility to positively impact early career physicians, investigators and trainees is presented here. Methods: We designed and conducted a virtual mentoring program pilot open to SNO’s multidisciplinary members in residency, fellowship, or early career phase, leveraging peer-mentoring sessions with mid-to late-career physician mentors. A curriculum with online resources was provided recommending groups meet for 6 sessions: 3 involving the mentor and 3 dedicated to peer-mentoring. Group assignments were based on time-zones and interests. Pre- and post-participation surveys assessed mentee experience. Descriptive statistics were used to assess participant demographics and survey results. Results: Our call for participation was broad; all 20 mentee applicants participated in 5 groups. Mentees were 90% women and 60% were from diverse racial and ethnic backgrounds. Most were aged 31-40 (75%) and junior faculty (50%) in neuro-oncology (65%). The 5 senior mentors (3 men and 3 of diverse race and ethnic backgrounds) practiced either neuro-oncology (3), neurosurgery (1) or radiation oncology (1). The proportion who reporting having a signature lecture increased from 15% to 62% during the pilot. A large majority reported their participation was worthwhile (85%), that they would participate again (92%) and would recommend it to others (92%). Feedback themes included positive personal growth, peer support, networking and job opportunities, access to CV reviews, lack of and desire for late career female mentors, and virtual scheduling constraints. While the pilot was limited by several variables, it was timely to connect participants in Q3 of 2020 early in the COVID-19 global pandemic. The virtual meeting environment created a venue to share and discuss topics such as work-life balance, burnout, leading through change and social connection. Despite not achieving 100% professional concordance, participants found the experience worthwhile. The tools and curriculum of topics provided was implemented differently across groups, leading to varied experiences. Finally, we did not have 100% post pilot follow up despite multiple attempts limiting our complete understanding of the pilot. Conclusions: This virtual mentorship pilot program proved feasible and of value in development of early career women and diverse individuals. A resource toolkit has been designed to scale and diffuse

    Metabolic Glycan Labeling of Cancer Cells Using Variably Acetylated Monosaccharides.

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    Funder: Engineering and Physical Sciences Research CouncilMethylcyclopropene (Cyoc)-tagged tetra-acetylated monosaccharides, and in particular mannosamine derivatives, are promising tools for medical imaging of cancer using metabolic oligosaccharide engineering and the extremely fast inverse electron-demand Diels-Alder bioorthogonal reaction. However, the in vivo potential of these monosaccharide derivatives has yet to be fully explored due to their low aqueous solubility. To address this issue, we sought to vary the extent of acetylation of Cyoc-tagged monosaccharides and probe its effect on the extent of glycan labeling in various cancer cell lines. We demonstrate that, in the case of AcxManNCyoc, tri- and diacetylated derivatives generated significantly enhanced cell labeling compared to the tetra-acetylated monosaccharide. In contrast, for the more readily soluble azide-tagged sugars, a decrease in acetylation led to decreased glycan labeling. Ac3ManNCyoc gave better labeling than the azido-tagged Ac4ManNAz and has significant potential for in vitro and in vivo imaging of glycosylated cancer biomarkers.CRUK grants C9545/A29580, C197/ A17242 and C197/A16465 Studentship from the EPSR
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