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Found 34655 matches. Displaying 21-30
Kerner G, Ramirez-Alejo N, Seeleuthner Y, Yang R, Ogishi M, Cobat A, Patin E, Quintana-Murci L, Boisson-Dupuis S, Casanova JL, Abel L
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Homozygosity for TYK2 P1104A underlies tuberculosis in about 1% of patients in a cohort of European ancestry

The human genetic basis of tuberculosis (TB) has long remained elusive. We recently reported a high level of enrichment in homozygosity for the common TYK2 P1104A variant in a heterogeneous cohort of patients with TB from non-European countries in which TB is endemic. This variant is homozygous in similar to 1/600 Europeans and similar to 1/5,000 people from other countries outside East Asia and sub-Saharan Africa. We report a study of this variant in the UK Biobank cohort. The frequency of P1104A homozygotes was much higher in patients with TB (6/620, 1%) than in controls (228/114,473, 0.2%), with an odds ratio (OR) adjusted for ancestry of 5.0 [95% confidence interval (CI): 1.96-10.31, P = 2 x 10(-3)]. Conversely, we did not observe enrichment for P1104A heterozygosity, or for TYK2 I684S or V362F homozygosity or heterozygosity. Moreover, it is unlikely that more than 10% of controls were infected with Mycobacterium tuberculosis, as 97% were of European genetic ancestry, born between 1939 and 1970, and resided in the United Kingdom. Had all of them been infected, the OR for developing TB upon infection would be higher. These findings suggest that homozygosity for TYK2 P1104A may account for similar to 1% of TB cases in Europeans.
Zaro BW, Vinogradova EV, Lazar DC, Blewett MM, Suciu RM, Takaya J, Studer S, de la Torre JC, Casanova JL, Cravatt BF, Teijaro JR
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Dimethyl Fumarate Disrupts Human Innate Immune Signaling by Targeting the IRAK4-MyD88 Complex

JOURNAL OF IMMUNOLOGY 2019 MAY 1; 202(9):2737-2746
Dimethyl fumarate (DMF) is a prescribed treatment for multiple sclerosis and has also been used to treat psoriasis. The electro-philicity of DMF suggests that its immunosuppressive activity is related to the covalent modification of cysteine residues in the human proteome. Nonetheless, our understanding of the proteins modified by DMF in human immune cells and the functional consequences of these reactions remains incomplete. In this study, we report that DMF inhibits human plasmacytoid dendritic cell function through a mechanism of action that is independent of the major electrophile sensor NRF2. Using chemical proteomics, we instead identify cysteine 13 of the innate immune kinase IRAK4 as a principal cellular target of DMF. We show that DMF blocks IRAK4-MyD88 interactions and IRAK4-mediated cytokine production in a cysteine 13-dependent manner. Our studies thus identify a proteomic hotspot for DMF action that constitutes a druggable protein-protein interface crucial for initiating innate immune responses.
McCarthy MW, de Asua DR, Gabbay E, Christos PJ, Fins JJ
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Frequency of Ethical Issues on a Hospitalist Teaching Service at an Urban, Tertiary Care Center

Little is known about the daily ethical conflicts encountered by hospitalists that do not prompt a formal clinical ethics consultation. We describe the frequencies of ethical issues identified during daily rounds on hospitalist teaching services at a metropolitan, tertiary-care, teaching hospital. Data were collected from September 2017 through May 2018 by two attending hospitalists from the ethics committee who were embedded on rounds. A total of 270 patients were evaluated and 113 ethical issues were identified in 77 of those patients. These issues most frequently involved discussions about goals of care, treatment refusals, decision-making capacity, discharge planning, cardiopulmonary resuscitation status, and pain management. Only five formal consults were brought to the Hospital Ethics Committee for these 270 patients. Our data are the first prospective description of ethical issues arising on academic hospitalist teaching services and are an important step in the development of a targeted ethics curriculum for hospitalists. (C) 2019 Society of Hospital Medicine
Dennis EJ, Goldman OV, Vosshall LB
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Aedes aegypti Mosquitoes Use Their Legs to Sense DEET on Contact

CURRENT BIOLOGY 2019 MAY 6; 29(9):1551-1556.e5
DEET (N, N-diethyl-meta-toluamide) is the most effective and widely used insect repellent, but its mechanism of action is both complex and controversial [1]. DEET acts on insect smell [2-6] and taste [7-11], and its olfactory mode of action requires the odorant coreceptor orco [2, 3, 6]. We previously observed that orco mutant female Aedes aegypti mosquitoes are strongly attracted to humans even in the presence of DEET, but they are rapidly repelled after contacting DEET-treated skin [6]. DEET inhibits food ingestion by Drosophila melanogaster flies, and this repellency is mediated by bitter taste neurons in the proboscis [9]. Similar neurons were identified in the mosquito proboscis, leading to the hypothesis that DEET repels on contact by activating an aversive bitter taste pathway [10]. To understand the basis of DEET contact chemorepellency, we carried out behavioral experiments and discovered that DEET acts by three distinct mechanisms: smell, ingestion, and contact. Like bitter tastants, DEET is a feeding deterrent when ingested, but its bitterness per se does not fully explain DEET contact chemorepellency. Mosquitoes blood fed on human arms treated with high concentrations of bitters, but rapidly avoided DEET-treated skin and did not blood feed. Insects detect tastants both through their proboscis and legs. We show that DEET contact chemorepellency is mediated exclusively by the tarsal segments of the legs and not the proboscis. This work establishes mosquito legs as the behaviorally relevant contact sensors of DEET. These results will inform the search for molecular mechanisms mediating DEET contact chemorepellency and novel contact-based insect repellents.
Schmidt F, Keele BF, Del Prete GQ, Voronin D, Fennessey CM, Soll S, Kane M, Raymond A, Gifford RJ, KewalRamani V, Lifson JD, Bieniasz PD, Hatziioannou T
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Derivation of simian tropic HIV-1 infectious clone reveals virus adaptation to a new host

To replicate in a new host, lentiviruses must adapt to exploit required host factors and evade species-specific antiviral proteins. Understanding how host protein variation drives lentivirus adaptation allowed us to expand the host range of HIV-1 to pigtail macaques. We have previously derived a viral swarm(in the blood of infected animals) that can cause AIDS in this new host. To further exploit this reagent, we generated infectious molecular clones (IMCs) from the viral swarm. We identified clones with high replicative capacity in pigtail peripheral blood mononuclear cells (PBMC) in vitro and used in vivo replication to select an individual IMC, named stHIV-A19 (for simian tropic HIV-1 clone A19), which recapitulated the phenotype obtained with the viral swarm. Adaptation of HIV-1 in macaques led to the acquisition of amino acid changes in viral proteins, such as capsid (CA), that are rarely seen in HIV-1-infected humans. Using stHIV-A19, we show that these CA changes confer a partial resistance to the host cell inhibitor Mx2 from pigtail macaques, but that complete resistance is associated with a fitness defect. Adaptation of HIV-1 to a new host will lead to a more accurate animal model and a better understanding of virus-host interactions.
Vahidnezhad H, Youssefian L, Saeidian H, Mansoori B, Jazayeri A, Azizpour A, Hesari KK, Yousefi M, Zeinali S, Jouanguy E, Casanova JL, Uitto J
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A CIB1 Splice-Site Founder Mutation in Families with Typical Epidermodysplasia Verruciformis

Stanley SA, Friedman JM
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Electromagnetic Regulation of Cell Activity

Theability to observe theeffects of rapidly and reversibly regulating cell activity in targeted cell populations has provided numerous physiologic insights. Over the last decade, a wide rangeof technologies have emerged for regulating cellular activity using optical, chemical, and, more recently, electromagnetic modalities. Electromagnetic fields can freely penetrate cells and tissue and their energy can be absorbed by metal particles. When released, the absorbed energy can in turn gate endogenous or engineered receptors and ion channels to regulate cell activity. In this manner, electromagnetic fields acting on external nanoparticles have been used to exert mechanical forces on cell membranes and organelles to generate heat and interact with thermally activated proteins or to induce receptor aggregation and intracellular signaling. More recently, technologies using genetically encoded nanoparticles composed of the iron storage protein, ferritin, have been used for targeted, temporal control of cell activity in vitro and in vivo. These tools provide a means for non invasively modulating gene expression, intracellular organelles, such as endosomes, and whole-cell activity both in vitro and in freely moving animals. The use of magnetic fields interacting with external or genetically encoded nanoparticles thus provides a rapid noninvasive means for regulating cell activity.
Maji B, Gangopadhyay SA, Lee M, Shi MC, Wu P, Heler R, Mok B, Lim D, Siriwardena SU, Paul B, Dancik V, Vetere A, Mesleh MF, Marraffini LA, Liu DR, Clemons PA, Wagner BK, Choudhary A
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A High-Throughput Platform to Identify Small-Molecule Inhibitors of CRISPR-Cas9

CELL 2019 MAY 2; 177(4):1067-1079.e19
The precise control of CRISPR-Cas9 activity is required for a number of genome engineering technologies. Here, we report a generalizable platform that provided the first synthetic small-molecule inhibitors of Streptococcus pyogenes Cas9 (SpCas9) that weigh <500 Da and are cell permeable, reversible, and stable under physiological conditions. We developed a suite of high-throughput assays for SpCas9 functions, including a primary screening assay for SpCas9 binding to the protospacer adjacent motif, and used these assays to screen a structurally diverse collection of natural-product-like small molecules to ultimately identify compounds that disrupt the SpCas9-DNA interaction. Using these synthetic anti-CRISPR small molecules, we demonstrated dose and temporal control of SpCas9 and catalytically impaired SpCas9 technologies, including transcription activation, and identified a pharmacophore for SpCas9 inhibition using structure-activity relationships. These studies establish a platform for rapidly identifying synthetic, miniature, cell-permeable, and reversible inhibitors against both SpCas9 and next-generation CRISPR-associated nucleases.
Roongthumskul Y, Maoileidigh DO, Hudspeth AJ
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Bilateral Spontaneous Otoacoustic Emissions Show Coupling between Active Oscillators in the Two Ears

BIOPHYSICAL JOURNAL 2019 MAY 21; 116(10):2023-2034
Spontaneous otoacoustic emissions (SOAEs) are weak sounds that emanate from the ears of tetrapods in the absence of acoustic stimulation. These emissions are an epiphenomenon of the inner ear's active process, which enhances the auditory system's sensitivity to weak sounds, but their mechanism of production remains a matter of debate. We recorded SOAEs simultaneously from the two ears of the tokay gecko and found that binaural emissions could be strongly correlated: some emissions occurred at the same frequency in both ears and were highly synchronized. Suppression of the emissions in one ear often changed the amplitude or shifted the frequency of emissions in the other. Decreasing the frequency of emissions from one ear by lowering its temperature usually reduced the frequency of the contralateral emissions. To understand the relationship between binaural SOAEs, we developed a mathematical model of the eardrums as noisy nonlinear oscillators coupled by the air within an animal's mouth. By according with the model, the results indicate that some SOAEs are generated bilaterally through acoustic coupling across the oral cavity. The model predicts that sound localization through the acoustic coupling between ears is influenced by the active processes of both ears.
Galea S, Vaughan RD
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Health as a Means, Not an End: A Public Health of Consequence, May 2019