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Found 37769 matches. Displaying 4541-4550
Gleicher N, Metzger J, Croft G, Kushnir VA, Albertini DF, Barad DH
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A single trophectoderm biopsy at blastocyst stage is mathematically unable to determine embryo ploidy accurately enough for clinical use

REPRODUCTIVE BIOLOGY AND ENDOCRINOLOGY 2017 APR 27; 15(?):? Article 33
Background: It has become increasingly apparent that the trophectoderm (TE) at blastocyst stage is much more mosaic than has been appreciated. Whether preimplantation genetic screening (PGS), utilizing a single TE biopsy (TEB), can reliably determine embryo ploidy has, therefore, increasingly been questioned in parallel. Methods: We for that reason here established 2 mathematical models to assess probabilities of false-negative and false-positive results of an on average 6-cell biopsy from an approximately 300-cell TE. This study was a collaborative effort between investigators at The Center for Human Reproduction in New York City and the Center for Studies in Physics and Biology and the Brivanlou Laboratory of Stem Cell Biology and Molecular Embryology, the latter two both at Rockefeller University in New York City. Results: Both models revealed that even under best case scenario, assuming even distribution of mosaicism in TE (since mosaicism is usually clonal, a highly unlikely scenario), a biopsy of at least 27 TE cells would be required to reach minimal diagnostic predictability from a single TEB. Conclusions: As currently performed, a single TEB is, therefore, mathematically incapable of reliably determining whether an embryo can be transferred or should be discarded. Since a single TEB, as currently performed, apparently is not representative of the complete TE, this study, thus, raises additional concern about the clinical utilization of PGS.
Wang WW, MacKinnon R
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Cryo-EM Structure of the Open Human Ether-a-go-go-Related K+ Channel hERG

CELL 2017 APR 20; 169(3):422-430.e10
The human ether-a-go-go-related potassium channel (hERG, Kv11.1) is a voltage-dependent channel known for its role in repolarizing the cardiac action potential. hERG alteration by mutation or pharmacological inhibition produces Long QT syndrome and the lethal cardiac arrhythmia torsade de pointes. We have determined the molecular structure of hERG to 3.8 angstrom using cryo-electron microscopy. In this structure, the voltage sensors adopt a depolarized conformation, and the pore is open. The central cavity has an atypically small central volume surrounded by four deep hydrophobic pockets, which may explain hERG's unusual sensitivity to many drugs. A subtle structural feature of the hERG selectivity filter might correlate with its fast inactivation rate, which is key to hERG's role in cardiac action potential repolarization.
Bowles NP, McEwen BS, Boutin-Foster C
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Trouble in transit: Organizational barriers to workers' health

AMERICAN JOURNAL OF INDUSTRIAL MEDICINE 2017 APR; 60(4):350-367
BackgroundValuable insights on the health and behavior of transit workers can be obtained from qualitative research that considers the social environment, which affects job performance and determines levels of perceived stress. MethodsUsing a grounded theory approach, semi-structured interviews were conducted with American transit workers (n=32). Recorded interviews were transcribed and analyzed using a constant comparative method. ResultsParticipants described categories related to entrenched organizational practices, particularly managements' leadership style, which created an atmosphere of distrust. High demanding work schedules, as a result of technological advances, were discussed in relation to diminished breaks, fatigue, and unhealthy diets. Transit workers also attributed increased work demands and irregular working hours to compromised time with family and friends. ConclusionsThe described barriers to positive health behaviors and social support underscore the need for interventions that ensure adequate breaks and recovery between shifts and increase safety for transit passengers. Am. J. Ind. Med. 60:350-367, 2017. (c) 2017 Wiley Periodicals, Inc.
Stevenson ML, Wang CQF, Abikhair M, Roudiani N, Felsen D, Krueger JG, Pavlick AC, Carucci JA
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Expression of Programmed Cell Death Ligand in Cutaneous Squamous Cell Carcinoma and Treatment of Locally Advanced Disease With Pembrolizumab

JAMA DERMATOLOGY 2017 APR 1; 153(4):299-303
IMPORTANCE Limited therapies are available in patients with inoperable locally advanced cutaneous squamous cell carcinoma (cSCC). OBJECTIVE To determine the efficacy of programmed cell death 1 receptor (PD-1) inhibitors in locally advanced cSCC. DESIGN, SETTING, AND PARTICIPANTS A single patient with locally advanced cSCC who declined surgery and radiotherapy underwent treatment with pembrolizumab, an anti-PD-1 antibody, at an academic dermatologic surgery section and cancer center. The patient was followed up for clinical and radiologic regression of cSCC. With the use of NanoString to amplify potential biomarkers, immunohistochemistry, and immunofluorescence, the ex vivo expression of PD-1 and a ligand (PD-L2) was assessed in 38 cSCC biopsy specimens from 24 patients with cSCC. Expression of PD-L1 and PD-L2 in the cSCC microenvironment was defined. INTERVENTION Pembrolizumab, 2mg/kg every 3 weeks, for 4 cycles. MAIN OUTCOMES AND MEASURES Expression of PD-L1 and PD-L2 in the cSCC microenvironment. RESULTS In 1 patient with locally advanced cSCC who was treated with pembrolizumab, nearly complete tumor regression was observed after 4 cycles of therapy. The NanoString technology used in 38 cSCC biopsy specimens from 24 patients with cSCC (19 men and 5 women; mean [SD] age, 76.4 [12.2] years) detected increased PD-1 and PD-L2 expression in high-risk cSCC. Immunohistochemical analysis confirmed enhanced expression of PD-1 and its ligands in cSCC with perineural invasion (mean [SEM] expression, 5.06 [1.27]; P =.05), superficial cSCC (mean [SEM] expression, 3.58 [1.50]; P =.15), organ transplant-associated cSCC (mean [SEM] expression, 3.01 [0.54]; P =.005), and infiltrative cSCC (mean [SD] expression, 2.01 [0.30]; P =.006) compared with normal skin specimens. In double-label immunofluorescence staining, CD11c(+), a marker ofmyeloid dendritic cells, colocalized with PD-L1 and PD-L2 in cSCC lesions. CONCLUSIONS AND RELEVANCE The favorable treatment response combined with significant involvement of PD-1 and PD ligands in cSCC lesions suggests that PD-1 blockade may be a viable therapeutic option for locally advanced cSCC and provides rationale for further investigation in future clinical trials.
Vargas FA, Furness AJS, Solomon I, Joshi K, Mekkaoui L, Lesko MH, Rota EM, Dahan R, Georgiou A, Sledzinska A, Ben Aissa A, Franz D, Sunderland MW, Wong YNS, Henry JY, O'Brien T, Nicol D, Challacombe B, Beers SA, Turajlic S, Gore M, Larkin J, Swanton C, Chester KA, Pule M, Ravetch JV, Marafioti T, Peggs KS, Quezada SA
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Fc-Optimized Anti-CD25 Depletes Tumor-Infiltrating Regulatory T Cells and Synergizes with PD-1 Blockade to Eradicate Established Tumors

IMMUNITY 2017 APR 18; 46(4):577-586
CD25 is expressed at high levels on regulatory T (Treg) cells and was initially proposed as a target for cancer immunotherapy. However, anti-CD25 antibodies have displayed limited activity against established tumors. We demonstrated that CD25 expression is largely restricted to tumor-infiltrating Treg cells in mice and humans. While existing anti-CD25 antibodies were observed to deplete Treg cells in the periphery, upregulation of the inhibitory Fc gamma receptor (Fc gamma R) IIb at the tumor site prevented intra-tumoral Treg cell depletion, which may underlie the lack of anti-tumor activity previously observed in pre-clinical models. Use of an anti-CD25 antibody with enhanced binding to activating Fc gamma Rs led to effective depletion of tumor-infiltrating Treg cells, increased effector to Treg cell ratios, and improved control of established tumors. Combination with anti-programmed cell death protein-1 antibodies promoted complete tumor rejection, demonstrating the relevance of CD25 as a therapeutic target and promising substrate for future combination approaches in immune-oncology.
Iaea DB, Mao S, Lund FW, Maxfield FR
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Role of STARD4 in sterol transport between the endocytic recycling compartment and the plasma membrane

MOLECULAR BIOLOGY OF THE CELL 2017 APR 15; 28(8):1111-1122
Cholesterol is an essential constituent of membranes in mammalian cells. The plasma membrane and the endocytic recycling compartment (ERC) are both highly enriched in cholesterol. The abundance and distribution of cholesterol among organelles are tightly controlled by a combination of mechanisms involving vesicular and nonvesicular sterol transport processes. Using the fluorescent cholesterol analogue dehydroergosterol, we examined sterol transport between the plasma membrane and the ERC using fluorescence recovery after photobleaching and a novel sterol efflux assay. We found that sterol transport between these organelles in a U2OS cell line has a t(1/2) = 12-15 min. Approximately 70% of sterol transport is ATP independent and therefore is nonvesicular. Increasing cellular cholesterol levels dramatically increases bidirectional transport rate constants, but decreases in cholesterol levels have only a modest effect. A soluble sterol transport protein, STARD4, accounts for similar to 25% of total sterol transport and similar to 33% of nonvesicular sterol transport between the plasma membrane and ERC. This study shows that nonvesicular sterol transport mechanisms and STARD4 in particular account for a large fraction of sterol transport between the plasma membrane and the ERC.
Yang H, Adam RC, Ge YJ, Hua ZL, Fuchs E
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Epithelial-Mesenchymal Micro-niches Govern Stem Cell Lineage Choices

CELL 2017 APR 20; 169(3):483-496.e13
Adult tissue stem cells (SCs) reside in niches, which, through intercellular contacts and signaling, influence SC behavior. Once activated, SCs typically give rise to short-lived transit-amplifying cells (TACs), which then progress to differentiate into their lineages. Here, using single-cell RNA-seq, we unearth unexpected heterogeneity among SCs and TACs of hair follicles. We trace the roots of this heterogeneity to micro-niches along epithelial-mesenchymal interfaces, where progenitors display molecular signatures reflective of spatially distinct local signals and intercellular interactions. Using lineage tracing, temporal single-cell analyses, and chromatin landscaping, we show that SC plasticity becomes restricted in a sequentially and spatially choreographed program, culminating in seven spatially arranged unilineage progenitors within TACs of mature follicles. By compartmentalizing SCs into microniches, tissues gain precise control over morphogenesis and regeneration: some progenitors specify lineages immediately, whereas others retain potency, preserving self-renewing features established early while progressively restricting lineages as they experience dynamic changes in microenvironment.
McEwen BS
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Integrative medicine: Breaking down silos of knowledge and practice an epigenetic approach

METABOLISM-CLINICAL AND EXPERIMENTAL 2017 APR; 69(?):S21-S29
The future of medicine is discussed in the context of epigenetic influences during the entire life course and the lived experiences of each person, avoiding as much as possible the "medicalization" of the individual and taking a more humanistic view. The reciprocal communication between brain and body via the neuroendocrine, autonomic, metabolic and immune systems and the plasticity of brain architecture provide the basis for devising better "top down" interventions that engage the whole person in working towards his or her welfare. The life course perspective emphasizes the importance of intervening early in life to prevent adverse early life experiences, including the effects of poverty, that can have lifelong consequences, referred to as "biological embedding". In the spirit of integrative, humanistic medicine, treatments that "open windows of plasticity" allow targeted behavioral interventions to redirect brain and body functions and behavior in healthier directions. Policies of government and the private sector, particularly at the local, community level, can create a supporting environment for such interventions. See "Common Ground for Health: Personalized, Precision and Social Medicine McEwen & Getz (C) 2017 Published by Elsevier Inc.
de Souza TL, Fernandes RCDC, da Silva JA, Alves VG, Coelho AG, Faria ACS, Simao NMMS, Souto JT, Deswarte C, Boisson-Dupuis S, Torgerson D, Casanova JL, Bustamante J, Medina-Acosta E
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Microbial Disease Spectrum Linked to a Novel IL-12R beta 1 N-Terminal Signal Peptide Stop-Gain Homozygous Mutation with Paradoxical Receptor Cell-Surface Expression

FRONTIERS IN MICROBIOLOGY 2017 APR 13; 8(?):? Article 616
Patients with Mendelian Susceptibility to Mycobacterial Diseases (MSMD) exhibit variable vulnerability to infections by mycobacteria and other intramacrophagic bacteria (e.g., Salmonella and Klebsiella) and fungi (e.g., Histoplasma, Candida, Paracoccidioides, Coccidioides, and Cryptococcus). The hallmark of MSMD is the inherited impaired production of interferon gamma (IFN-gamma) or the lack of response to it. Mutations in the interleukin (IL)-12 receptor subunit beta 1 (IL12RB1) gene accounts for 38% of cases of MSMD. Most IL12RB1 pathogenic allele mutations, including ten known stop-gain variants, cause IL-12R beta 1 complete deficiency (immunodeficiency-30, IMD30) by knocking out receptor cell-surface expression. IL12RB1 loss-of-function genotypes impair both IL-12 and IL-23 responses. Here, we assess the health effects of a rare, novel IL12RB1 stop-gain homozygous genotype with paradoxical IL-12R beta 1 cell-surface expression. We appraise four MSMD children from three unrelated Brazilian kindreds by clinical consultation, medical records, and genetic and immunologic studies. The clinical spectrum narrowed down to Bacillus Calmette-Guerin (BCG) vaccine-related suppurative adenitis in all patients with one death, and recrudescence in two, histoplasmosis, and recurrence in one patient, extraintestinal salmonellosis in one child, and cutaneous vasculitis in another. In three patients, we established the homozygous Trp7Ter predicted loss-of-function inherited genotype and inferred it from the heterozygote parents of the fourth case. The Trp7Ter mutation maps to the predicted IL-12R beta 1 N-terminal signal peptide sequence. BCG- or phytohemagglutinin-blasts from the three patients have reduced cell-surface expression of IL-12R beta 1 with impaired production of IFN-gamma and IL-17A. Screening of 227 unrelated healthy subjects from the same geographic region revealed one heterozygous genotype (allele frequency 0.0022) vs. one in over 841,883 public genome/exomes. We also show that the carriers bear European ancestry-informative alleles and share the extended CACCAGTCCGG IL12RB1 haplotype that occurs worldwide with a frequency of 8.4%. We conclude that the novel IL12RB1 N-terminal signal peptide stop-gain loss-of-function homozygous genotype confers IL-12R beta 1 deficiency with varying severity and early-onset age through diminished cell-surface expression of an impaired IL-12R beta 1 polypeptide. We firmly recommend attending to warning signs of IMD30 in children who are HIV-1 negative with a history of adverse effects to the BCG vaccine and presenting with recurrent Histoplasma spp. and extraintestinal Salmonella spp. infections.
Arias CF, Arias CF
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How do red blood cells know when to die?

ROYAL SOCIETY OPEN SCIENCE 2017 APR; 4(4):? Article 160850
Human red blood cells (RBCs) are normally phagocytized by macrophages of splenic and hepatic sinusoids at 120 days of age. The destruction of RBCs is ultimately controlled by antagonist effects of phosphatidylserine (PS) and CD47 on the phagocytic activity of macrophages. In this work, we introduce a conceptual model that explains RBC lifespan as a consequence of the dynamics of these molecules. Specifically, we suggest that PS and CD47 define a molecular algorithm that sets the timing of RBC phagocytosis. We show that significant changes in RBC lifespan described in the literature can be explained as alternative outcomes of this algorithm when it is executed in different conditions of oxygen availability. The theoretical model introduced here provides a unified framework to understand a variety of empirical observations regarding RBC biology. It also highlights the role of RBC lifespan as a key element of RBC homeostasis.