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Rainer Malik, Martin Dichgans
Stroke, ischemic stroke and subtypes of ischemic stroke display substantial heritability. Compared to related vascular conditions, the number of established risk loci reaching genome-wide significance for association with stroke is still in the lower range, particularly for etiological stroke subtypes such as large artery atherosclerotic stroke or small vessel stroke. Nevertheless, for individual loci substantial progress has been made in determining the specific mechanisms mediating stroke risk. In this review, we present a roadmap for functional follow-up of common risk variants associated with stroke...
March 15, 2018: Cardiovascular Research
Kelvin G K Goh, Minh-Duy Phan, Brian M Forde, Teik Min Chong, Wai-Fong Yin, Kok-Gan Chan, Glen C Ulett, Matthew J Sweet, Scott A Beatson, Mark A Schembri
Uropathogenic Escherichia coli (UPEC) is a major cause of urinary tract and bloodstream infections and possesses an array of virulence factors for colonization, survival, and persistence. One such factor is the polysaccharide K capsule. Among the different K capsule types, the K1 serotype is strongly associated with UPEC infection. In this study, we completely sequenced the K1 UPEC urosepsis strain PA45B and employed a novel combination of a lytic K1 capsule-specific phage, saturated Tn 5 transposon mutagenesis, and high-throughput transposon-directed insertion site sequencing (TraDIS) to identify the complement of genes required for capsule production...
October 24, 2017: MBio
Cynthia A Kalita, Gregory A Moyerbrailean, Christopher Brown, Xiaoquan Wen, Francesca Luca, Roger Pique-Regi
Motivation: The majority of the human genome is composed of non-coding regions containing regulatory elements such as enhancers, which are crucial for controlling gene expression. Many variants associated with complex traits are in these regions, and may disrupt gene regulatory sequences. Consequently, it is important to not only identify true enhancers but also to test if a variant within an enhancer affects gene regulation. Recently, allele-specific analysis in high-throughput reporter assays, such as massively parallel reporter assays (MPRAs), have been used to functionally validate non-coding variants...
March 1, 2018: Bioinformatics
Ying Liu, Takuma Irie, Tetsushi Yada, Yutaka Suzuki
In recent years, the dramatic increase in the number of applications for massively parallel reporter assay (MPRA) technology has produced a large body of data for various purposes. However, a computational model that can be applied to decipher regulatory codes for diverse MPRAs does not exist yet. Here, we propose a new computational method to predict the transcriptional activity of MPRAs, as well as luciferase reporter assays, based on the TRANScription FACtor database. We employed regression trees and multivariate adaptive regression splines to obtain these predictions and considered a feature redundancy-dependent formula for conventional regression trees to enable adaptation to diverse data...
July 27, 2017: Nucleic Acids Research
Asha Kakkanat, Minh-Duy Phan, Alvin W Lo, Scott A Beatson, Mark A Schembri
Uropathogenic Escherichia coli (UPEC) is the cause of ~75% of all urinary tract infections (UTIs) and is increasingly associated with multidrug resistance. This includes UPEC strains from the recently emerged and globally disseminated sequence type 131 (ST131), which is now the dominant fluoroquinolone-resistant UPEC clone worldwide. Most ST131 strains are motile and produce H4-type flagella. Here, we applied a combination of saturated Tn5 mutagenesis and transposon directed insertion site sequencing (TraDIS) as a high throughput genetic screen and identified 30 genes associated with enhanced motility of the reference ST131 strain EC958...
2017: PloS One
Alexander D Giddey, Elise de Kock, Kehilwe C Nakedi, Shaun Garnett, Andrew J M Nel, Nelson C Soares, Jonathan M Blackburn
In the last 40 years only one new antitubercular drug has been approved, whilst resistance to current drugs, including rifampicin, is spreading. Here, we used the model organism Mycobacterium smegmatis to study mechanisms of phenotypic mycobacterial resistance, employing quantitative mass spectrometry-based proteomics to investigate the temporal effects of sub-lethal concentrations of rifampicin on the mycobacterial proteome at time-points corresponding to early response, onset of bacteriostasis and early recovery...
March 6, 2017: Scientific Reports
Haoyang Zeng, Matthew D Edwards, Yuchun Guo, David K Gifford
We present a novel ensemble-based computational framework, EnsembleExpr, that achieved the best performance in the Fourth Critical Assessment of Genome Interpretation expression quantitative trait locus "(eQTL)-causal SNPs" challenge for identifying eQTLs and prioritizing their gene expression effects. eQTLs are genome sequence variants that result in gene expression changes and are thus prime suspects in the search for contributions to the causality of complex traits. When EnsembleExpr is trained on data from massively parallel reporter assays, it accurately predicts reporter expression levels from unseen regulatory sequences and identifies sequence variants that exhibit significant changes in reporter expression...
September 2017: Human Mutation
Michael A Beer
We participated in the Critical Assessment of Genome Interpretation eQTL challenge to further test computational models of regulatory variant impact and their association with human disease. Our prediction model is based on a discriminative gapped-kmer SVM (gkm-SVM) trained on genome-wide chromatin accessibility data in the cell type of interest. The comparisons with massively parallel reporter assays (MPRA) in lymphoblasts show that gkm-SVM is among the most accurate prediction models even though all other models used the MPRA data for model training, and gkm-SVM did not...
September 2017: Human Mutation
Brett B Maricque, Joseph D Dougherty, Barak A Cohen
Recent large-scale genomics efforts to characterize the cis-regulatory sequences that orchestrate genome-wide expression patterns have produced impressive catalogues of putative regulatory elements. Most of these sequences have not been functionally tested, and our limited understanding of the non-coding genome prevents us from predicting which sequences are bona fide cis-regulatory elements. Recently, massively parallel reporter assays (MPRAs) have been deployed to measure the activity of putative cis-regulatory sequences in several biological contexts, each with specific advantages and distinct limitations...
October 23, 2016: Nucleic Acids Research
Jason Ernst, Alexandre Melnikov, Xiaolan Zhang, Li Wang, Peter Rogov, Tarjei S Mikkelsen, Manolis Kellis
Massively parallel reporter assays (MPRAs) enable nucleotide-resolution dissection of transcriptional regulatory regions, such as enhancers, but only few regions at a time. Here we present a combined experimental and computational approach, Systematic high-resolution activation and repression profiling with reporter tiling using MPRA (Sharpr-MPRA), that allows high-resolution analysis of thousands of regions simultaneously. Sharpr-MPRA combines dense tiling of overlapping MPRA constructs with a probabilistic graphical model to recognize functional regulatory nucleotides, and to distinguish activating and repressive nucleotides, using their inferred contribution to reporter gene expression...
November 2016: Nature Biotechnology
Ryan N Doan, Byoung-Il Bae, Beatriz Cubelos, Cindy Chang, Amer A Hossain, Samira Al-Saad, Nahit M Mukaddes, Ozgur Oner, Muna Al-Saffar, Soher Balkhy, Generoso G Gascon, Marta Nieto, Christopher A Walsh
Comparative analyses have identified genomic regions potentially involved in human evolution but do not directly assess function. Human accelerated regions (HARs) represent conserved genomic loci with elevated divergence in humans. If some HARs regulate human-specific social and behavioral traits, then mutations would likely impact cognitive and social disorders. Strikingly, rare biallelic point mutations-identified by whole-genome and targeted "HAR-ome" sequencing-showed a significant excess in individuals with ASD whose parents share common ancestry compared to familial controls, suggesting a contribution in 5% of consanguineous ASD cases...
October 6, 2016: Cell
Peicheng Du, Charles D Sohaskey, Lanbo Shi
Mycobacterium tuberculosis can persist for years in the hostile environment of the host in a non-replicating or slowly replicating state. While active disease predominantly results from reactivation of a latent infection, the molecular mechanisms of M. tuberculosis reactivation are still poorly understood. We characterized the physiology and global transcriptomic profiles of M. tuberculosis during reactivation from hypoxia-induced non-replicating persistence. We found that M. tuberculosis reactivation upon reaeration was associated with a lag phase, in which the recovery of cellular physiological and metabolic functions preceded the resumption of cell replication...
2016: Frontiers in Microbiology
Ilias Georgakopoulos-Soares, Naman Jain, Jesse M Gray, Martin Hemberg
MOTIVATION: With the rapid advances in DNA synthesis and sequencing technologies and the continuing decline in the associated costs, high-throughput experiments can be performed to investigate the regulatory role of thousands of oligonucleotide sequences simultaneously. Nevertheless, designing high-throughput reporter assay experiments such as massively parallel reporter assays (MPRAs) and similar methods remains challenging. RESULTS: We introduce MPRAnator, a set of tools that facilitate rapid design of MPRA experiments...
January 1, 2017: Bioinformatics
Jacob C Ulirsch, Satish K Nandakumar, Li Wang, Felix C Giani, Xiaolan Zhang, Peter Rogov, Alexandre Melnikov, Patrick McDonel, Ron Do, Tarjei S Mikkelsen, Vijay G Sankaran
Genome-wide association studies (GWAS) have successfully identified thousands of associations between common genetic variants and human disease phenotypes, but the majority of these variants are non-coding, often requiring genetic fine-mapping, epigenomic profiling, and individual reporter assays to delineate potential causal variants. We employ a massively parallel reporter assay (MPRA) to simultaneously screen 2,756 variants in strong linkage disequilibrium with 75 sentinel variants associated with red blood cell traits...
June 2, 2016: Cell
Ryan Tewhey, Dylan Kotliar, Daniel S Park, Brandon Liu, Sarah Winnicki, Steven K Reilly, Kristian G Andersen, Tarjei S Mikkelsen, Eric S Lander, Stephen F Schaffner, Pardis C Sabeti
Although studies have identified hundreds of loci associated with human traits and diseases, pinpointing causal alleles remains difficult, particularly for non-coding variants. To address this challenge, we adapted the massively parallel reporter assay (MPRA) to identify variants that directly modulate gene expression. We applied it to 32,373 variants from 3,642 cis-expression quantitative trait loci and control regions. Detection by MPRA was strongly correlated with measures of regulatory function. We demonstrate MPRA's capabilities for pinpointing causal alleles, using it to identify 842 variants showing differential expression between alleles, including 53 well-annotated variants associated with diseases and traits...
June 2, 2016: Cell
Leonardo M R Ferreira, Torsten B Meissner, Tarjei S Mikkelsen, William Mallard, Charles W O'Donnell, Tamara Tilburgs, Hannah A B Gomes, Raymond Camahort, Richard I Sherwood, David K Gifford, John L Rinn, Chad A Cowan, Jack L Strominger
HLA-G, a nonclassical HLA molecule uniquely expressed in the placenta, is a central component of fetus-induced immune tolerance during pregnancy. The tissue-specific expression of HLA-G, however, remains poorly understood. Here, systematic interrogation of the HLA-G locus using massively parallel reporter assay (MPRA) uncovered a previously unidentified cis-regulatory element 12 kb upstream of HLA-G with enhancer activity, Enhancer L Strikingly, clustered regularly-interspaced short palindromic repeats (CRISPR)/Cas9-mediated deletion of this enhancer resulted in ablation of HLA-G expression in JEG3 cells and in primary human trophoblasts isolated from placenta...
May 10, 2016: Proceedings of the National Academy of Sciences of the United States of America
Aditi Sharma, Tige Rustad, Gaurang Mahajan, Arun Kumar, Kanury V S Rao, Sharmistha Banerjee, David R Sherman, Shekhar C Mande
The 60 kDa heat shock proteins, also known as Cpn60s (GroELs) are components of the essential protein folding machinery of the cell, but are also dominant antigens in many infectious diseases. Although generally essential for cellular survival, in some organisms such as Mycobacterium tuberculosis, one or more paralogous Cpn60s are known to be dispensable. In M. tuberculosis, Cpn60.2 (GroEL2) is essential for cell survival, but the biological role of the non-essential Cpn60.1 (GroEL1) is still elusive. To understand the relevance of Cpn60...
March 2016: Tuberculosis
Xiaogang Wang, Wen Chen, Shengtao Mei, Xudong Chen
We propose an algorithm for jointly designing two phase-only masks (POMs) that allow for the encryption and noise-free retrieval of triple images. The images required for optical retrieval are first stored in quick-response (QR) codes for noise-free retrieval and flexible readout. Two sparse POMs are respectively calculated from two different images used as references for authentication based on modified Gerchberg-Saxton algorithm (GSA) and pixel extraction, and are then used as support constraints in a modified double-phase retrieval algorithm (MPRA), together with the above-mentioned QR codes...
2015: Scientific Reports
Samaneh Saedi, Masoud Youssefi, Hadi Safdari, Saman Soleimanpour, Parviz Marouzi, Kiarash Ghazvini
Advances in DNA sequencing have greatly enhanced the molecular epidemiology studies. In order to assess evolutionary and phylogenetic relation of Mycobacterium tuberculosis isolates several gene targets were evaluated. In this study, appropriate fragments of 5 highly variable genes (rpsL, mprA, lipR, katG, and fgd1 genes) were sequenced. The sequence data were analyzed with neighbor-joining method using mega and Geneious software. The phylogenetic trees analyzes revealed that the discriminatory power of lipR is much stronger than that observed in the other genes...
October 2015: Current Microbiology
Ravindranath Dhulipalla, Shruthi Bade, Appaiah Chowdary Bollepalli, Kishore Kumar Katuri, Narasimha Swamy Devulapalli, Chakrapani Swarna
OBJECTIVE: The aim of the present study was to evaluate the periodontal risk of individuals using periodontal risk assessment (PRA) model and modified PRA model. MATERIALS AND METHODS: A total of 50 patients with chronic periodontitis, age 30-60 years were selected randomly and charting of the periodontal status was performed and those who met the inclusion criteria were enrolled in the study. Parameters recorded were- percentage of sites with bleeding on probing (BOP), number of sites with pocket depths (PD) ≥ 5mm, number of the teeth lost, bone loss (BL)/age ratio, Clinical attachment loss(CAL)/age ratio, diabetic and smoking status, dental status, systemic factors like diabetes were assessed...
February 2015: Journal of Clinical and Diagnostic Research: JCDR
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