The most common cystic fibrosis (CF) causing mutation, deletion of phenylalanine 508 (deltaF508 or Phe508del), results in functional expression defect of the CF transmembrane conductance regulator ...(CFTR) at the apical plasma membrane (PM) of secretory epithelia, which is attributed to the degradation of the misfolded channel at the endoplasmic reticulum (ER). Deletion of phenylalanine 670 (deltaF670) in the yeast oligomycin resistance 1 gene (YOR1, an ABC transporter) of Saccharomyces cerevisiae phenocopies the deltaF508-CFTR folding and trafficking defects. Genome-wide phenotypic (phenomic) analysis of the Yor1-deltaF670 biogenesis identified several modifier genes of mRNA processing and translation, which conferred oligomycin resistance to yeast. Silencing of orthologues of these candidate genes enhanced the deltaF508-CFTR functional expression at the apical PM in human CF bronchial epithelia. Although knockdown of RPL12, a component of the ribosomal stalk, attenuated the translational elongation rate, it increased the folding efficiency as well as the conformational stability of the deltaF508-CFTR, manifesting in 3-fold augmented PM density and function of the mutant. Combination of RPL12 knockdown with the corrector drug, VX-809 (lumacaftor) restored the mutant function to ~50% of the wild-type channel in primary CFTRdeltaF508/deltaF508 human bronchial epithelia. These results and the observation that silencing of other ribosomal stalk proteins partially rescue the loss-of-function phenotype of deltaF508-CFTR suggest that the ribosomal stalk modulates the folding efficiency of the mutant and is a potential therapeutic target for correction of the deltaF508-CFTR folding defect.
Background. Abciximab during percutaneous coronary revascularization reduces ischemic complications, but concern exists regarding increased bleeding risk should emergency coronary surgical procedures ...be required.
Methods. Outcomes were assessed among 85 patients who required coronary artery bypass grafting operations after coronary intervention in two randomized placebo-controlled trials of abciximab. Comparisons were made between patients in the pooled placebo and abciximab groups.
Results. The incidence of coronary surgical procedures was 2.17% and 1.28% among patients randomized to placebo and abciximab, respectively (
p = 0.021). Platelet transfusions were administered to 32% and 52% of patients in the placebo and abciximab groups, respectively (
p = 0.059). Rates of major blood loss were 79% and 88% in the placebo and abciximab groups, respectively (
p = 0.27); transfusions of packed red blood cells or whole blood were administered in 74% and 80% of patients, respectively (
p = 0.53). Surgical reexploration for bleeding was required in 3% and 12% of patients, respectively. Death and myocardial infarction tended to occur less frequently among patients who had received abciximab.
Conclusions. Urgent coronary artery bypass grafting operations can be performed without an incremental increase in major hemorrhagic risk among patients on abciximab therapy.
Background Directional coronary atherectomy and percutaneous transluminal coronary angioplasty have both been used in symptomatic patients with coronary saphenous vein bypass graft stenoses. The ...relative merits of plaque excision and removal versus balloon dilatation remain uncertain. We compared outcomes after directional coronary atherectomy or angioplasty in patients with de novo bypass graft stenoses. Methods and Results Fifty-four North American and European sites randomized 305 patients with de novo vein graft lesions to atherectomy (n=149) or angioplasty (n=156). Quantitative coronary angiography at a core laboratory assessed initial and 6-month results. Initial angiographic success was greater with atherectomy (89.2% versus 79.0%), as was initial luminal gain (1.45 versus 1.12 mm, P <.001). Distal embolization was increased with atherectomy ( P =.012), and a trend was shown toward more non–Q-wave myocardial infarction ( P =.09). Although the 6-month net minimum luminal diameter gain was 0.68 mm for atherectomy and 0.50 mm for angioplasty, the restenosis rates were similar, 45.6% for atherectomy and 50.5% for angioplasty ( P =.491). At 6 months, there was a trend toward decreased repeated target-vessel interventions for atherectomy ( P =.092); in addition, 13.2% of patients treated with atherectomy versus 22.4% of the angioplasty patients ( P =.041) required repeated percutaneous intervention of the initial target lesion. Conclusions Atherectomy of de novo vein graft lesions was associated with improved initial angiographic success and luminal diameter but also with increased distal embolization. There was no difference in 6-month restenosis rates, although primary atherectomy patients tended to require fewer target-vessel revascularization procedures.
Colorectal cancer (CRC) screening in the United States is suboptimal. We conducted a national survey to learn about CRC screening perceptions and practices among trainees who perform CRC screening ...tests including those enrolled in Gastroenterology and Hepatology (GIH), General and Colorectal Surgery, and Diagnostic and Abdominal Radiology training programs.
Program directors/administrators (PDs/PAs) from 642 programs were contacted by e-mail with an invitation to forward our survey to trainees in their programs. Participating trainees then completed an anonymous, Web-based questionnaire.
A total of 130/642 (20%) PDs/PAs forwarded our survey to their trainees, with responses received from 476 trainees (80 GIH, 261 surgery, 135 radiology). Colonoscopy was felt to be the best CRC screening test at reducing CRC mortality, with patient-related factors perceived as greater barriers than system-related factors. No single guideline was deemed very influential on CRC screening practices by most trainees. A total of 2 of 5 above-average risk patient profiles were not recognized by most trainees. Colonoscopy was selected as the preferred follow-up test for a positive CRC screening test by most trainees. However, 34% of respondents chose an option other than colonoscopy alone for follow-up of a positive fecal occult blood test.
Based on data from this national survey of gastroenterology, surgery, and radiology trainees, opportunities exist for curricular changes that may help enhance current perceptions and practices of trainees who perform CRC screening tests.
A low loss, high isolation, broadband RF switch has been developed using a novel type of field effect transistor structure that exploits the use of a super-lattice structure in combination with a ...three dimensional, castellated gate to achieve excellent RF switch performance. Using an AlGaN/GaN super-lattice epitaxial layer, this Super-Lattice Castellated Field Effect Transistor (SLCFET) was used to build 1-18 GHz SPDT RF switches. Measured insertion loss of the SPDT at 10 GHz was -0.4 dB, with -35 dB of isolation and -23 dB of return loss, along with a measured linearity OIP3 value 62 dBm and a P0.1dB of 34 dBm.
Areas of variable lung attenuation forming a "mosaic pattern" are occasionally seen on computed tomography (CT) or high-resolution CT (HRCT) images of the lungs. This CT mosaic pattern of lung ...attenuation is a nonspecific finding that can reflect the presence of vascular disease, airway abnormalities, or ground-glass interstitial or air-space infiltrates. However, it is often possible to distinguish among these categories. In small airways disease and pulmonary vascular disease, the pulmonary vessels within the lucent regions of lung are small relative to the vessels in the more opaque lung. In infiltrative diseases, the vessels are more uniform in size throughout the different regions of lung attenuation. The distinction of small airways disease from primary vascular disease requires the use of paired inspiratory/expiratory CT scans. The terms "mosaic perfusion" or "mosaic oligemia" have also been used to describe this heterogeneous pattern of lung attenuation. We believe that the term "mosaic pattern of lung attenuation" is preferable when describing areas of variable lung attenuation because the term "mosaic perfusion" implies pulmonary vascular pathology.
Background The overall influence of gene interaction in human disease is unknown. In cystic fibrosis (CF) a single allele of the cystic fibrosis transmembrane conductance regulator (CFTR-DELAF508) ...accounts for most of the disease. In cell models, CFTR-DELAF508 exhibits defective protein biogenesis and degradation rather than proper trafficking to the plasma membrane where CFTR normally functions. Numerous genes function in the biogenesis of CFTR and influence the fate of CFTR-DELAF508. However it is not known whether genetic variation in such genes contributes to disease severity in patients. Nor is there an easy way to study how numerous gene interactions involving CFTR-DELAF would manifest phenotypically. Methods To gain insight into the function and evolutionary conservation of a gene interaction network that regulates biogenesis of a misfolded ABC transporter, we employed yeast genetics to develop a 'phenomic' model, in which the CFTR-DELAF508-equivalent residue of a yeast homolog is mutated (Yor1-DELAF670), and where the genome is scanned quantitatively for interaction. We first confirmed that Yor1-DELAF undergoes protein misfolding and has reduced half-life, analogous to CFTR-DELAF. Gene interaction was then assessed quantitatively by growth curves for approximately 5,000 double mutants, based on alteration in the dose response to growth inhibition by oligomycin, a toxin extruded from the cell at the plasma membrane by Yor1. Results From a comparative genomic perspective, yeast gene interactions influencing Yor1-DELAF biogenesis were representative of human homologs previously found to modulate processing of CFTR-DELAF in mammalian cells. Additional evolutionarily conserved pathways were implicated by the study, and a DELAF-specific pro-biogenesis function of the recently discovered ER membrane complex (EMC) was evident from the yeast screen. This novel function was validated biochemically by siRNA of an EMC ortholog in a human cell line expressing CFTR-DELAF508. The precision and accuracy of quantitative high throughput cell array phenotyping (Q-HTCP), which captures tens of thousands of growth curves simultaneously, provided powerful resolution to measure gene interaction on a phenomic scale, based on discrete cell proliferation parameters. Conclusion We propose phenomic analysis of Yor1-DELAF as a model for investigating gene interaction networks that can modulate cystic fibrosis disease severity. Although the clinical relevance of the Yor1-DELAF gene interaction network for cystic fibrosis remains to be defined, the model appears to be informative with respect to human cell models of CFTR-DELAF. Moreover, the general strategy of yeast phenomics can be employed in a systematic manner to model gene interaction for other diseases relating to pathologies that result from protein misfolding or potentially any disease involving evolutionarily conserved genetic pathways. Keywords: Gene interaction, Genetic buffering, Genotype-phenotype complexity, Phenomics, Quantitative high throughput cell array phenotyping (Q-HTCP), Cystic fibrosis transmembrane conductance regulator (CFTR), ER membrane complex (EMC), ATP binding cassette (ABC) transporter, Membrane protein biogenesis, Yeast model of human disease, Comparative functional genomics
Coccolithophores are an important component of the Earth system, and, as calcifiers, their possible susceptibility to ocean acidification is of major concern. Laboratory studies at enhanced pCO₂ ...levels have produced divergent results without overall consensus. However, it has been predicted from these studies that, although calcification may not be depressed in all species, acidification will produce "a transition in dominance from more to less heavily calcified coccolithophores" Ridgwell A, et al., (2009) Biogeosciences 6:2611-2623. A recent observational study Beaufort L, et al., (2011) Nature 476:80–83 also suggested that coccolithophores are less calcified in more acidic conditions. We present the results of a large observational study of coccolithophore morphology in the Bay of Biscay. Samples were collected once a month for over a year, along a 1,000-km-long transect. Our data clearly show that there is a pronounced seasonality in the morphotypes of Emiliania huxleyi, the most abundant coccolithophore species. Whereas pH and CaCO ₃ saturation are lowest in winter, the E. huxleyi population shifts from <10% (summer) to >90% (winter) of the heavily calcified form. However, it is unlikely that the shifts in carbonate chemistry alone caused the morphotype shift. Our finding that the most heavily calcified morphotype dominates when conditions are most acidic is contrary to the earlier predictions and raises further questions about the fate of coccolithophores in a high-CO₂ world.
We report that a single growth factor, NM23-H1, enables serial passaging of both human ES and iPS cells in the absence of feeder cells, their conditioned media or bFGF in a fully defined xeno-free ...media on a novel defined, xeno-free surface. Stem cells cultured in this system show a gene expression pattern indicative of a more "naive" state than stem cells grown in bFGF-based media. NM23-H1 and MUC1* growth factor receptor cooperate to control stem cell self-replication. By manipulating the multimerization state of NM23-H1, we override the stem cell's inherent programming that turns off pluripotency and trick the cells into continuously replicating as pluripotent stem cells. Dimeric NM23-H1 binds to and dimerizes the extra cellular domain of the MUC1* transmembrane receptor which stimulates growth and promotes pluripotency. Inhibition of the NM23-H1/MUC1* interaction accelerates differentiation and causes a spike in miR-145 expression which signals a cell's exit from pluripotency.
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