Publications by authors named "MacIsaac K"

Polygenic risk scores (PRSs) hold promise for disease risk assessment and prevention. The Genomic Medicine at Veterans Affairs (GenoVA) Study is addressing three main challenges to the clinical implementation of PRSs in preventive care: defining and determining their clinical utility, implementing them in time-constrained primary care settings, and countering their potential to exacerbate healthcare disparities. The study processes used to test patients, report their PRS results to them and their primary care providers (PCPs), and promote the use of those results in clinical decision-making are modeled on common practices in primary care.

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Polygenic risk scores (PRS) may improve risk-stratification in preventive care. Their clinical implementation will depend on primary care physicians' (PCPs) uptake. We surveyed PCPs in a national physician database about the perceived clinical utility, benefits, and barriers to the use of PRS in preventive care.

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Tumor heterogeneity is a major challenge for oncology drug discovery and development. Understanding of the spatial tumor landscape is key to identifying new targets and impactful model systems. Here, we test the utility of spatial transcriptomics (ST) for oncology discovery by profiling 40 tissue sections and 80,024 capture spots across a diverse set of tissue types, sample formats, and RNA capture chemistries.

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Background: Validated computable eligibility criteria use real-world data and facilitate the conduct of clinical trials. The Genomic Medicine at VA (GenoVA) Study is a pragmatic trial of polygenic risk score testing enrolling patients without known diagnoses of 6 common diseases: atrial fibrillation, coronary artery disease, type 2 diabetes, breast cancer, colorectal cancer, and prostate cancer. We describe the validation of computable disease classifiers as eligibility criteria and their performance in the first 16 months of trial enrollment.

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Despite the increasing interest in targeting stromal elements of the tumor microenvironment, we still face tremendous challenges in developing adequate therapeutics to modify the tumor stromal landscape. A major obstacle to this is our poor understanding of the phenotypic and functional heterogeneity of stromal cells in tumors. Herein, we perform an unbiased interrogation of tumor mesenchymal cells, delineating the co-existence of distinct subsets of cancer-associated fibroblasts (CAFs) in the microenvironment of murine carcinomas, each endowed with unique phenotypic features and functions.

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Interferons (IFNs) are cytokines that play a critical role in limiting infectious and malignant diseases . Emerging data suggest that the strength and duration of IFN signaling can differentially impact cancer therapies, including immune checkpoint blockade . Here, we characterize the output of IFN signaling, specifically IFN-stimulated gene (ISG) signatures, in primary tumors from The Cancer Genome Atlas.

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Article Synopsis
  • Racial and ethnic disparities in breast cancer mortality are increasing, yet genomic studies often overlook diverse populations, highlighting a gap in research.
  • The study analyzed 194 breast cancer patients from Nigeria alongside 1,037 patients from The Cancer Genome Atlas (TCGA), revealing that Nigerian tumors have distinct genomic features indicating more aggressive cancer biology.
  • Key findings include higher rates of specific mutations in Nigerian patients and the identification of novel genes linked to breast cancer, potentially paving the way for tailored treatments for underrepresented groups.
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Cancer-associated fibroblasts (CAFs) are generally associated with poor clinical outcome. CAFs support tumor growth in a variety of ways and can suppress antitumor immunity and response to immunotherapy. However, a precise understanding of CAF contributions to tumor growth and therapeutic response is lacking.

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Nasopharyngeal carcinoma (NPC) is an Epstein-Barr virus (EBV) associated cancer characterized by a poor prognosis and a high level of lymphocyte infiltrate. Genetic hallmarks of NPC are not completely known but include deletion of the p16 () locus and mutations in NF-κB pathway components, with a relatively low total mutational load. To better understand the genetic landscape, an integrated genomic analysis was performed using a large clinical cohort of treatment-naïve NPC tumor specimens.

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Background: HPV infection causes cervical cancer, mediated in part by the degradation of Scribble via the HPV E6 oncoprotein. Recently, Scribble has been shown to be an important regulator of the Hippo signaling cascade. Deregulation of the Hippo pathway induces an abnormal cellular transformation, epithelial to mesenchymal transition, which promotes oncogenic progression.

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Recent studies have elucidated the molecular mechanism of RORγT transcriptional regulation of Th17 differentiation and function. RORγT was initially identified as a transcription factor required for thymopoiesis by maintaining survival of CD4CD8 (DP) thymocytes. While RORγ antagonists are currently being developed to treat autoimmunity, it remains unclear how RORγT inhibition may impact thymocyte development.

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Objectives: Human airway epithelial cells are the principal target of human rhinovirus (HRV), a common cold pathogen that triggers the majority of asthma exacerbations. The objectives of this study were 1) to evaluate an in vitro air liquid interface cultured human airway epithelial cell model for HRV infection, and 2) to identify gene expression patterns associated with asthma intrinsically and/or after HRV infection using this model.

Methods: Air-liquid interface (ALI) human airway epithelial cell cultures were prepared from 6 asthmatic and 6 non-asthmatic donors.

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Unlabelled: Approximately 30% of rheumatoid arthritis patients achieve inadequate response to anti-TNF biologics. Attempts to identify molecular biomarkers predicting response have met with mixed success. This may be attributable, in part, to the variable and subjective disease assessment endpoints with large placebo effects typically used to classify patient response.

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The high failure rate of new therapeutic mechanisms tested in clinical development has spurred an upsurge in research dedicated to discovering biomarker readouts that can improve decision-making. Increasingly, systems biology and genomic technologies, such as transcriptional profiling, are being leveraged to aid in the discovery of biomarker readouts. For inflammatory and immunological diseases, such as rheumatoid arthritis (RA) and asthma, progress has been made in developing biomarkers to monitor disease activity, prediction of response to therapy, and pharmacodynamic (PD) measurements.

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Background: Celiac disease can present with mild or nongastrointestinal symptoms, and may escape timely recognition. The treatment of celiac disease involves a gluten-free diet, which is complex and challenging.

Objective: To evaluate clinical features and symptom recovery on a gluten-free diet in a Canadian adult celiac population.

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Objective: Strict adherence to a gluten-free diet is the only treatment for coeliac disease. The gluten-free diet is complex, costly and impacts on all activities involving food, making it difficult to maintain for a lifetime. The purpose of this cross-sectional study was to evaluate the difficulties experienced, the strategies used and the emotional impact of following a gluten-free diet among Canadians with coeliac disease.

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We developed PolyA-seq, a strand-specific and quantitative method for high-throughput sequencing of 3' ends of polyadenylated transcripts, and used it to globally map polyadenylation (polyA) sites in 24 matched tissues in human, rhesus, dog, mouse, and rat. We show that PolyA-seq is as accurate as existing RNA sequencing (RNA-seq) approaches for digital gene expression (DGE), enabling simultaneous mapping of polyA sites and quantitative measurement of their usage. In human, we confirmed 158,533 known sites and discovered 280,857 novel sites (FDR < 2.

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Chromatin immunoprecipitation (ChIP) experiments allow the location of transcription factors to be determined across the genome. Subsequent analysis of the sequences of the identified regions allows binding to be localized at a higher resolution than can be achieved by current high-throughput experiments without sequence analysis and may provide important insight into the regulatory programs enacted by the protein of interest. In this chapter we review the tools, workflow, and common pitfalls of such analyses and recommend strategies for effective motif discovery from these data.

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Understanding the mechanistic basis of transcriptional regulation has been a central focus of molecular biology since its inception. New high-throughput chromatin immunoprecipitation experiments have revealed that most regulatory proteins bind thousands of sites in mammalian genomes. However, the functional significance of these binding sites remains unclear.

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The Wilms' tumor suppressor 1 (WT1) gene encodes a DNA- and RNA-binding protein that plays an essential role in nephron progenitor differentiation during renal development. To identify WT1 target genes that might regulate nephron progenitor differentiation in vivo, we performed chromatin immunoprecipitation (ChIP) coupled to mouse promoter microarray (ChIP-chip) using chromatin prepared from embryonic mouse kidney tissue. We identified 1663 genes bound by WT1, 86% of which contain a previously identified, conserved, high-affinity WT1 binding site.

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Src family tyrosine kinases are important signaling enzymes in the neuronal growth cone, and they have been implicated in axon guidance; however, the detailed localization, trafficking, and cellular functions of Src kinases in live growth cones are unclear. Here, we cloned two novel Aplysia Src kinases, termed Src1 and Src2, and we show their association with both the plasma membrane and the microtubule cytoskeleton in the growth cone by live cell imaging, immunocytochemistry, and cell fractionation. Activated Src2 is enriched in filopodia tips.

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We demonstrate that the binding sites for highly conserved transcription factors vary extensively between human and mouse. We mapped the binding of four tissue-specific transcription factors (FOXA2, HNF1A, HNF4A and HNF6) to 4,000 orthologous gene pairs in hepatocytes purified from human and mouse livers. Despite the conserved function of these factors, from 41% to 89% of their binding events seem to be species specific.

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Foxp3+CD4+CD25+ regulatory T (T(reg)) cells are essential for the prevention of autoimmunity. T(reg) cells have an attenuated cytokine response to T-cell receptor stimulation, and can suppress the proliferation and effector function of neighbouring T cells. The forkhead transcription factor Foxp3 (forkhead box P3) is selectively expressed in T(reg) cells, is required for T(reg) development and function, and is sufficient to induce a T(reg) phenotype in conventional CD4+CD25- T cells.

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