Publications by authors named "Merchant S"

Previously, transplantation of ovaries from young, cycling mice into old, postreproductive-age mice increased life span and decreased cardiomyopathy at death. We anticipated that the same factors that increased life span and decreased cardiomyopathy could also influence the progression of orthopedic disease. At 11 months of age, prepubertally ovariectomized and ovary-intact mice (including reproductively cycling and acyclic mice) received new 60-day-old ovaries.

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Photosynthetic microorganisms typically have multiple isoforms of the electron transfer protein ferredoxin, although we know little about their exact functions. Surprisingly, a Chlamydomonas reinhardtii mutant null for the ferredoxin-5 gene (FDX5) completely ceased growth in the dark, with both photosynthetic and respiratory functions severely compromised; growth in the light was unaffected. Thylakoid membranes in dark-maintained fdx5 mutant cells became severely disorganized concomitant with a marked decrease in the ratio of monogalactosyldiacylglycerol to digalactosyldiacylglycerol, major lipids in photosynthetic membranes, and the accumulation of triacylglycerol.

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Background And Aims: EMR and endoscopic submucosal dissection (ESD) are widely accepted in Asia for treatment of early gastric cancer (EGC). Few studies have examined lymph node (LN) metastasis of EGC in Western populations. We sought to examine EGC and LN metastasis in a heterogeneous Western population.

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Purpose: To seek a better understanding of the effect of organized capillary flow on the MR diffusion-weighted signal.

Methods: A theoretical framework was proposed to describe the diffusion-weighted MR signal, which was then validated both numerically using a realistic model of capillary network and experimentally in an animal model of isolated perfused heart preparation with myocardial blood flow verified by means of direct arterial spin labeling measurements.

Results: Microcirculation in organized tissues gave rise to an MR signal that could be described as a combination of the bi-exponential behavior of conventional intravoxel incoherent motion (IVIM) theory and diffusion tensor imaging (DTI) -like anisotropy of the vascular signal, with the flow-related pseudo diffusivity represented as the linear algebraic product between the encoding directional unit vector and an appropriate tensor entity.

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Background And Objectives: Central apnea complicates, and may be the presenting complaint in, bronchiolitis. Our objective was to prospectively derive candidate clinical decision rules (CDRs) to identify infants in the emergency department (ED) who are at risk for central apnea.

Methods: We conducted a prospective observational study over 8 years.

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Reactive oxygen species (ROS) are produced by and have the potential to be damaging to all aerobic organisms. In photosynthetic organisms, they are an unavoidable byproduct of electron transfer in both the chloroplast and mitochondrion. Here, we employ the reference unicellular green alga Chlamydomonas reinhardtii to identify the effect of H2O2 on gene expression by monitoring the changes in the transcriptome in a time-course experiment.

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The green alga Chlamydomonas reinhardtii undergoes gametogenesis and mating upon nitrogen starvation. While the steps involved in its sexual reproductive cycle have been extensively characterized, the genome-wide transcriptional and epigenetic changes underlying different life cycle stages have yet to be fully described. Here, we performed transcriptome and methylome sequencing to quantify expression and DNA methylation from vegetative and gametic cells of each mating type and from zygotes.

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The green alga Chlamydomonas reinhardtii is a useful model organism for investigating diverse biological processes, such as photosynthesis and chloroplast biogenesis, flagella and basal body structure/function, cell growth and division, and many others. We combined a highly synchronous photobioreactor culture system with frequent temporal sampling to characterize genome-wide diurnal gene expression in Chlamydomonas. Over 80% of the measured transcriptome was expressed with strong periodicity, forming 18 major clusters.

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The efficiency of gene expression in all organisms depends on the nucleotide composition of the coding region. GC content and codon usage are the two key sequence features known to influence gene expression, but the underlying molecular mechanisms are not entirely clear. Here we have determined the relative contributions of GC content and codon usage to the efficiency of nuclear gene expression in the unicellular green alga Chlamydomonas reinhardtii.

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Although interactions of metallic nanoparticles (NPs) with various microorganisms have been previously explored, few studies have examined how metal sensitivity impacts NP toxicity. The present study investigated the effects of copper NPs (Cu-NP) exposure on the model alga Chlamydomonas reinhardtii in the presence and absence of the essential micronutrient copper. The toxic ranges for Cu-NPs and the ionic control, CuCl2 , were determined using a high-throughput adenosine triphosphate (ATP)-based fluorescence assay.

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Chlamydomonas reinhardtii is a widely used reference organism in studies of photosynthesis, cilia, and biofuels. Most research in this field uses a few dozen standard laboratory strains that are reported to share a common ancestry, but exhibit substantial phenotypic differences. In order to facilitate ongoing Chlamydomonas research and explain the phenotypic variation, we mapped the genetic diversity within these strains using whole-genome resequencing.

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Radiation therapists (RTs) plan and deliver radiotherapy treatment for patients diagnosed with cancer. They need to communicate regularly with their patients and may have a role to play in reducing patient anxiety and distress. The objectives were to explore how the environment of radiotherapy departments supports or inhibits communication generally and information giving and supportive care provision in particular.

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Autophagy is an intracellular self-degradation pathway by which eukaryotic cells recycle their own material in response to specific stress conditions. Exposure to high concentrations of metals causes cell damage, although the effect of metal stress on autophagy has not been explored in photosynthetic organisms. In this study, we investigated the effect of metal excess on autophagy in the model unicellular green alga Chlamydomonas reinhardtii.

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Background: Readmission rates after cancer surgery are infrequently reported, and better understanding of the etiologies for readmission is necessary. We sought to investigate the frequency, timing, and etiologies for hospital readmission after surgery for gastric cancer and whether readmission correlates with clinical outcomes.

Study Design: Hospital readmission was examined through linkage of the California Cancer Registry with the Office of Statewide Health Planning and Development database.

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The world's crop productivity is stagnating whereas population growth, rising affluence, and mandates for biofuels put increasing demands on agriculture. Meanwhile, demand for increasing cropland competes with equally crucial global sustainability and environmental protection needs. Addressing this looming agricultural crisis will be one of our greatest scientific challenges in the coming decades, and success will require substantial improvements at many levels.

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Background: Immediate reconstruction rates after mastectomy are increasing but remain low. Little is known about hospital readmissions after these procedures. The authors studied unscheduled readmissions after immediate reconstruction.

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Mutation of Arabidopsis thaliana NAD(P)H DEHYDROGENASE C1 (NDC1; At5g08740) results in the accumulation of demethylphylloquinone, a late biosynthetic intermediate of vitamin K1. Gene coexpression and phylogenomics analyses showed that conserved functional associations occur between vitamin K biosynthesis and NDC1 homologs throughout the prokaryotic and eukaryotic lineages. Deletion of Synechocystis ndbB, which encodes for one such homolog, resulted in the same defects as those observed in the cyanobacterial demethylnaphthoquinone methyltransferase knockout.

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Recent animal work has suggested that cochlear synapses are more vulnerable than hair cells in both noise-induced and age-related hearing loss. This synaptopathy is invisible in conventional histopathological analysis, because cochlear nerve cell bodies in the spiral ganglion survive for years, and synaptic analysis requires special immunostaining or serial-section electron microscopy. Here, we show that the same quadruple-immunostaining protocols that allow synaptic counts, hair cell counts, neuronal counts and differentiation of afferent and efferent fibers in mouse can be applied to human temporal bones, when harvested within 9 h post-mortem and prepared as dissected whole mounts of the sensory epithelium and osseous spiral lamina.

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Background: Hospital cancer registries are only required to report gastrointestinal stromal tumors (GISTs) if labeled malignant or metastatic, leading to potential loss of cases in national cancer registries. Our objective was to determine whether GISTs are underreported in the US.

Methods: Retrospective review of pathology reports between 2010 and 2013 with diagnosis of GIST was performed at two academic medical centers.

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The reaction between vinyl radical, C2H3, and 1,3-butadiene, 1,3-C4H6, has long been recognized as a potential route to benzene, particularly in 1,3-butadiene flames, but the lack of reliable rate coefficients has hindered assessments of its true contribution. Using laser flash photolysis and visible laser absorbance (λ = 423.2 nm), we measured the overall rate coefficient for C2H3 + 1,3-C4H6, k1, at 297 K ≤ T ≤ 494 K and 4 ≤ P ≤ 100 Torr.

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Hydatid disease is commonly encountered in specific geographic areas of the world. Hydatidosis affects multiple organs and has diverse radiologic presentations. Sonography remains an important modality for diagnosing this condition, as it optimally detects cystic structures, floating membranes, and debris.

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Background: Irreversible electroporation (IRE) is a non-thermal injury tissue ablation technique that uses electrical pulses to cause cell death. IRE damages the endothelial cells of blood vessels; however these cells re-grow, and thus IRE does not result in permanent damage to blood vessels. We report the novel use of IRE for ablation of microscopically positive margins after resection of colorectal liver metastases (CRLM) impinging on hepatic veins.

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The biogenesis of the major thylakoid protein complexes of the photosynthetic apparatus requires auxiliary proteins supporting individual assembly steps. Here, we identify a plant lineage specific gene, CGL160, whose homolog, atp1, co-occurs with ATP synthase subunits in an operon-like arrangement in many cyanobacteria. Arabidopsis thaliana T-DNA insertion mutants, which no longer accumulate the nucleus-encoded CGL160 protein, accumulate less than 25% of wild-type levels of the chloroplast ATP synthase.

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