352 research outputs found

    Outer Retinal Structure in Best Vitelliform Macular Dystrophy

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    Importance Demonstrating the utility of adaptive optics scanning light ophthalmoscopy (AOSLO) to assess outer retinal structure in Best vitelliform macular dystrophy (BVMD). Objective To characterize outer retinal structure in BVMD using spectral-domain optical coherence tomography (SD-OCT) and AOSLO. Design, Setting, and Participants Prospective, observational case series. Four symptomatic members of a family with BVMD with known BEST1 mutation were recruited at the Advanced Ocular Imaging Program research lab at the Medical College of Wisconsin Eye Institute, Milwaukee. Intervention Thickness of 2 outer retinal layers corresponding to photoreceptor inner and outer segments was measured using SD-OCT. Photoreceptor mosaic AOSLO images within and around visible lesions were obtained, and cone density was assessed in 2 subjects. Main Outcome and Measure Photoreceptor structure. Results Each subject was at a different stage of BVMD, with photoreceptor disruption evident by AOSLO at all stages. When comparing SD-OCT and AOSLO images from the same location, AOSLO images allowed for direct assessment of photoreceptor structure. A variable degree of retained photoreceptors was seen within all lesions. The photoreceptor mosaic immediately adjacent to visible lesions appeared contiguous and was of normal density. Fine hyperreflective structures were visualized by AOSLO, and their anatomical orientation and size were consistent with Henle fibers. Conclusions and Relevance The AOSLO findings indicate that substantial photoreceptor structure persists within active lesions, accounting for good visual acuity in these patients. Despite previous reports of diffuse photoreceptor outer segment abnormalities in BVMD, our data reveal normal photoreceptor structure in areas adjacent to clinical lesions. This study demonstrates the utility of AOSLO for understanding the spectrum of cellular changes that occur in inherited degenerations such as BVMD. Photoreceptors are often significantly affected at various stages of inherited degenerations, and these changes may not be readily apparent with current clinical imaging instrumentation

    Complete genome sequence of the filamentous anoxygenic phototrophic bacterium Chloroflexus aurantiacus

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    <p>Abstract</p> <p>Background</p> <p><it>Chloroflexus aurantiacus </it>is a thermophilic filamentous anoxygenic phototrophic (FAP) bacterium, and can grow phototrophically under anaerobic conditions or chemotrophically under aerobic and dark conditions. According to 16S rRNA analysis, <it>Chloroflexi </it>species are the earliest branching bacteria capable of photosynthesis, and <it>Cfl. aurantiacus </it>has been long regarded as a key organism to resolve the obscurity of the origin and early evolution of photosynthesis. <it>Cfl. aurantiacus </it>contains a chimeric photosystem that comprises some characters of green sulfur bacteria and purple photosynthetic bacteria, and also has some unique electron transport proteins compared to other photosynthetic bacteria.</p> <p>Methods</p> <p>The complete genomic sequence of <it>Cfl. aurantiacus </it>has been determined, analyzed and compared to the genomes of other photosynthetic bacteria.</p> <p>Results</p> <p>Abundant genomic evidence suggests that there have been numerous gene adaptations/replacements in <it>Cfl. aurantiacus </it>to facilitate life under both anaerobic and aerobic conditions, including duplicate genes and gene clusters for the alternative complex III (ACIII), auracyanin and NADH:quinone oxidoreductase; and several aerobic/anaerobic enzyme pairs in central carbon metabolism and tetrapyrroles and nucleic acids biosynthesis. Overall, genomic information is consistent with a high tolerance for oxygen that has been reported in the growth of <it>Cfl. aurantiacus</it>. Genes for the chimeric photosystem, photosynthetic electron transport chain, the 3-hydroxypropionate autotrophic carbon fixation cycle, CO<sub>2</sub>-anaplerotic pathways, glyoxylate cycle, and sulfur reduction pathway are present. The central carbon metabolism and sulfur assimilation pathways in <it>Cfl. aurantiacus </it>are discussed. Some features of the <it>Cfl. aurantiacus </it>genome are compared with those of the <it>Roseiflexus castenholzii </it>genome. <it>Roseiflexus castenholzii </it>is a recently characterized FAP bacterium and phylogenetically closely related to <it>Cfl. aurantiacus</it>. According to previous reports and the genomic information, perspectives of <it>Cfl. aurantiacus </it>in the evolution of photosynthesis are also discussed.</p> <p>Conclusions</p> <p>The genomic analyses presented in this report, along with previous physiological, ecological and biochemical studies, indicate that the anoxygenic phototroph <it>Cfl. aurantiacus </it>has many interesting and certain unique features in its metabolic pathways. The complete genome may also shed light on possible evolutionary connections of photosynthesis.</p

    The Organization of Agricultural Research in Western Developed Countries

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    This paper reviews agricultural research structural and organization changes in western developed countries, examines new financing prospects for agricultural research, and provides some tentative conclusions about which organizations are best positioned to provide services for the 21st century. Giventhat these countries faces many similar economic, political, scientific, andagroclimatic factors and fiscal issues, we canexpect a similar set of similar new developments thathave potentially important and widespread long-run implications. After three common developments are outlined, principles ofimpure public good financing are applied leading to the following agricultural science policy recommendations (i) new political jurisdictions should be formed to finance research, e.g., new alliances across countries and subregions within large countries, (ii) intellecmal property rights should be strengthened to increase the total amount and share oftotal (public and private) agricultural research that is privately financed and conducted, i.e., the private sector should find it profitable to undertake a large share ofapplied research but not be expected to finance public sector agriculmral research, (iii) the public sector should redirect its research efforts increasingly to areas that are socially worthwhile but not privately undertaken, e.g.,in the basic and pretechnology areas, on envkonmental, resources, food safety and human nutrition, and policy. Finally, large countries that have developed asystem ofshared public and private financmg and performance and decentralized public support ofagricultural research seem best position for meeting the needs ofthe 21st centur

    Jet-induced cratering of a granular surface with application to lunar spaceports

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    The erosion of lunar soil by rocket exhaust plumes is investigated experimentally. This has identified the diffusion-driven flow in the bulk of the sand as an important but previously unrecognized mechanism for erosion dynamics. It has also shown that slow regime cratering is governed by the recirculation of sand in the widening geometry of the crater. Scaling relationships and erosion mechanisms have been characterized in detail for the slow regime. The diffusion-driven flow occurs in both slow and fast regime cratering. Because diffusion-driven flow had been omitted from the lunar erosion theory and from the pressure cratering theory of the Apollo and Viking era, those theories cannot be entirely correct.Comment: 13 pages, link to published version: http://cedb.asce.org/cgi/WWWdisplay.cgi?090000

    Protein disulfide-isomerase interacts with a substrate protein at all stages along its folding pathway

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    In contrast to molecular chaperones that couple protein folding to ATP hydrolysis, protein disulfide-isomerase (PDI) catalyzes protein folding coupled to formation of disulfide bonds (oxidative folding). However, we do not know how PDI distinguishes folded, partly-folded and unfolded protein substrates. As a model intermediate in an oxidative folding pathway, we prepared a two-disulfide mutant of basic pancreatic trypsin inhibitor (BPTI) and showed by NMR that it is partly-folded and highly dynamic. NMR studies show that it binds to PDI at the same site that binds peptide ligands, with rapid binding and dissociation kinetics; surface plasmon resonance shows its interaction with PDI has a Kd of ca. 10−5 M. For comparison, we characterized the interactions of PDI with native BPTI and fully-unfolded BPTI. Interestingly, PDI does bind native BPTI, but binding is quantitatively weaker than with partly-folded and unfolded BPTI. Hence PDI recognizes and binds substrates via permanently or transiently unfolded regions. This is the first study of PDI's interaction with a partly-folded protein, and the first to analyze this folding catalyst's changing interactions with substrates along an oxidative folding pathway. We have identified key features that make PDI an effective catalyst of oxidative protein folding – differential affinity, rapid ligand exchange and conformational flexibility

    Low levels of specularity support operational color constancy, particularly when surface and illumination geometry can be inferred

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    We tested whether surface specularity alone supports operational color constancy—the ability to discriminate changes in illumination or reflectance. Observers viewed short animations of illuminant or reflectance changes in rendered scenes containing a single spherical surface and were asked to classify the change. Performance improved with increasing specularity, as predicted from regularities in chromatic statistics. Peak performance was impaired by spatial rearrangements of image pixels that disrupted the perception of illuminated surfaces but was maintained with increased surface complexity. The characteristic chromatic transformations that are available with nonzero specularity are useful for operational color constancy, particularly if accompanied by appropriate perceptual organization

    The use of chiropractors by older adults in the United States

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    <p>Abstract</p> <p>Background</p> <p>In a nationally representative sample of United States Medicare beneficiaries, we examined the extent of chiropractic use, factors associated with seeing a chiropractor, and predictors of the volume of chiropractic use among those having seen one.</p> <p>Methods</p> <p>We performed secondary analyses of baseline interview data on 4,310 self-respondents who were 70 years old or older when they first participated in the Survey on Assets and Health Dynamics Among the Oldest Old (AHEAD). The interview data were then linked to their Medicare claims. Multiple logistic and negative binomial regressions were used.</p> <p>Results</p> <p>The average annual rate of chiropractic use was 4.6%. During the four-year period (two years before and two years after each respondent's baseline interview), 10.3% had one or more visits to a chiropractor. African Americans and Hispanics, as well as those with multiple depressive symptoms and those who lived in counties with lower than average supplies of chiropractors were much less likely to use them. The use of chiropractors was much more likely among those who drank alcohol, had arthritis, reported pain, and were able to drive. Chiropractic services did not substitute for physician visits. Among those who had seen a chiropractor, the volume of chiropractic visits was lower for those who lived alone, had lower incomes, and poorer cognitive abilities, while it was greater for the overweight and those with lower body limitations.</p> <p>Conclusion</p> <p>Chiropractic use among older adults is less prevalent than has been consistently reported for the United States as a whole, and is most common among Whites, those reporting pain, and those with geographic, financial, and transportation access.</p

    Consensus Statement on Bone Conduction Devices and Active Middle Ear Implants in Conductive and Mixed Hearing Loss

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    Nowadays, several options are available to treat patients with conductive or mixed hearing loss. Whenever surgical intervention is not possible or contra-indicated, and amplification by a conventional hearing device (e.g., behind-the-ear device) is not feasible, then implantable hearing devices are an indispensable next option. Implantable bone-conduction devices and middle-ear implants have advantages but also limitations concerning complexity/invasiveness of the surgery, medical complications, and effectiveness. To counsel the patient, the clinician should have a good overview of the options with regard to safety and reliability as well as unequivocal technical performance data. The present consensus document is the outcome of an extensive iterative process including ENT specialists, audiologists, health-policy scientists, and representatives/technicians of the main companies in this field. This document should provide a first framework for procedures and technical characterization to enhance effective communication between these stakeholders, improving health care
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