570 research outputs found

    Imaging spectroscopy and combinatorial mutagenesis of light harvesting II antenna from Rhodobacter capsulatus

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    Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 1994.Includes bibliographical references (leaves 102-112).by Ellen R. Goldman.Ph.D

    Isolation of anti-toxin single domain antibodies from a semi-synthetic spiny dogfish shark display library

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    <p>Abstract</p> <p>Background</p> <p>Shark heavy chain antibody, also called new antigen receptor (NAR), consists of one single Variable domain (V<sub>H</sub>), containing only two complementarity-determining regions (CDRs). The antigen binding affinity and specificity are mainly determined by these two CDRs. The good solubility, excellent thermal stability and complex sequence variation of small single domain antibodies (sdAbs) make them attractive alternatives to conventional antibodies. In this report, we construct and characterize a diversity enhanced semi-synthetic NAR V display library based on naturally occurring NAR V sequences.</p> <p>Results</p> <p>A semi-synthetic shark sdAb display library with a complexity close to 1e9 was constructed. This was achieved by introducing size and sequence variations in CDR3 using randomized CDR3 primers of three different lengths. Binders against three toxins, staphylococcal enterotoxin B (SEB), ricin, and botulinum toxin A (BoNT/A) complex toxoid, were isolated from panning the display library. Soluble sdAbs from selected binders were purified and evaluated using direct binding and thermal stability assays on the Luminex 100. In addition, sandwich assays using sdAb as the reporter element were developed to demonstrate their utility for future sensor applications.</p> <p>Conclusion</p> <p>We demonstrated the utility of a newly created hyper diversified shark NAR displayed library to serve as a source of thermal stable sdAbs against a variety of toxins.</p

    Assuring access to data for chemical evaluations

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    Background: A database for studies used for U.S. Environmental Protection Agency (EPA) pesticide and chemical reviews would be an excellent resource for increasing transparency and improving systematic assessments of pesticides and chemicals. There is increased demand for disclosure of raw data from studies used by the U.S. EPA in these reviews. Objectives: Because the Information Quality Act (IQA) of 2001 provides an avenue for request of raw data, we reviewed all IQA requests to the U.S. EPA in 2002–2012 and the U.S. EPA’s responses. We identified other mechanisms to access such data: public access databases, the Freedom of Information Act (FOIA), and reanalysis by a third party. Discussion: Only two IQA requests to the U.S. EPA were for raw data. Both of these were fulfilled under FOIA, not the IQA. Barriers to the U.S. EPA’s proactive collection of all such data include costs to the U.S. EPA and researchers, significant time burdens for researchers, and major regulatory delays. The U.S. EPA regulatory authority in this area is weak, especially for research conducted in the past, not funded by the U.S. government, and/or conducted abroad. The U.S. EPA is also constrained by industry confidential business information (CBI) claims for regulatory testing data under U.S. chemical and pesticide laws. The National Institutes of Health Clinical Trials database systematically collects statistical data about clinical trials but not raw data; this database may be a model for data from studies of chemicals and pesticides. Conclusions: A database that registers studies and obtains systematic sets of parameters and results would be more feasible than a system that attempts to make all raw data available proactively. Such a proposal would not obviate rights under the IQA to obtain raw data at a later point

    Anatomical Knowledge Retention in Changing Curricula

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    Traditionally anatomy is one of the first subjects taught in medical school. Practicing physicians have commented on medical students’ poor anatomical knowledge in surgically oriented clerkships. Literature also shows that correlating clinical and anatomical sciences throughout early medical education may improve anatomical knowledge retention. With major medical school curricular changes happening across the nation, more quantitative data confirming this correlation is needed. The medical curriculum at the George Washington University School of Medicine recently underwent reorganization, transforming an earlier discipline-based curriculum to that of an integrated system-based one. In order to determine whether reorganization has an effect on anatomical knowledge retention, comparisons of anatomical knowledge between classes in the different curricula were made. Students from the last class of the discipline-based curriculum and students from the first class of the new, integrated curriculum completed the same 27question test before beginning their general surgery and obstetrics and gynecology (OB/Gyn) rotations. Scores for specific anatomy categories related to general surgery and OB/Gyn were then analyzed and compared between classes. Comparing the scores from the 2013 and 2016 cohorts, there was an overall decrease in retention from 65.69% to 63.64% (Table 1). Item analysis per topic revealed a mean decrease in surgical anatomy and OB/Gyn anatomy retention of 2.53% and 1.58%, respectively. There was a 21.6% increase in inguinal canal anatomy retention and a 17.33% increase in appendix related questions. There was also a 12.02% decrease in fallopian tube anatomy retention. In conclusion, when comparing the 2013 to the 2016 data there were overall decreases in retention for the anatomy as it relates to general surgery and OB/Gyn; however improvements were noted for specific topic areas. These results suggest that the change in retention is apparent and multifactorial. The differences between surgical anatomy retention and OB/Gyn anatomy retention scores may be related to the way the subject matter was organized and presented, or how the anatomic foundational knowledge was integrated with its clinical relevance. Although integrative learning has been associated with better retention, more studies will have to be conducted to validate this statement. Finally, analyzing the subject matter, curriculum structure, clinical focus, and objectives should be evaluated moving forward

    Further Expansion of Nested E-Modules to Address Anatomical Knowledge Retention in Medical Students entering the Obstetrics and Gynecology Clinical Rotation

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    Previous work has shown that a curriculum that included computer-based teaching modules (“e-modules”) improved retention of preclinical concepts of gross anatomy, as medical students transitioned to the third-year OBGYN clerkship. However, data showed that deficiencies still remained in areas not addressed by the curriculum. Two of these areas were microscopic anatomy and embryology, where retention scores were 4% and 38%, respectively (Jurjus et al., unpublished). Based on this research, an expanded series of e-modules will be created to target these anatomical topics that still require improvement, specifically in microscopic anatomy and embryology: 1) Ultrasound in Pregnancy using Embryological Knowledge 2) Pregnancy Timeline and the Embryo and 3) The Cervix in Health and Disease. The learning objectives correlate clinical medicine and anatomical categories. Once finalized, these e-modules will be live on the Himmelfarb Library website. By further expanding the number of e-modules available to students, we hope to improve retention of clinically relevant anatomical knowledge in adult learners. Funding: GW Office of the Vice Provost for Teaching and Learning, Spring 2013 Grants for High Impact Teaching and Learning Practices

    Improving Anatomical Knowledge Through Interactive Modules on the OB/GYN Clinical Clerkship

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    The goal of this study is to evaluate the impact of a newly designed interactive method of teaching clinically relevant anatomy to medical students on the OB/GYN clerkship. A 20-question multiple-choice exam was administered to 143 consenting third-year medical students at the beginning and end of each OB/GYN rotation. Students participated in a skills lab with preparatory e-modules that linked anatomy to clinical applications during each rotation. Topics included perineal muscle anatomy (laceration), anterior abdominal wall anatomy (cesarean section), vulvovaginal and uterine anatomy (IUD), and pelvic organ, vasculature, and neural anatomy (hysterectomy). Mean scores improved significantly after the nesting of interactive modules, increasing from 55.1% to 67.4% (p\u3c0.001). In comparing mean scores from questions that were covered in the e-modules (intervention) and questions that were not covered in the e-modules (non-intervention), students improved significantly after receiving an intervention (9.4% difference; p\u3c0.001). Therefore, completing the clerkship without an intervention did not yield significant improvement in relevant anatomical knowledge, compared to intervention. Thus, nesting anatomical science into the clinical curriculum through preparatory e-modules and hands-on anatomy lab sessions may improve clinically-significant anatomy knowledge. This data may be used to increase longitudinal integration of the various disciplines across the undergraduate medical curriculum

    A triangular three-dye DNA switch capable of reconfigurable molecular logic

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    Structural DNA nanotechnology has developed profoundly in the last several years allowing for the creation of increasingly sophisticated devices capable of discrete sensing, locomotion, and molecular logic. The latter research field is particularly attractive as it provides information processing capabilities that may eventually be applied in situ, for example in cells, with potential for even further coupling to an active response such as drug delivery. Rather than design a new DNA assembly for each intended logic application, it would be useful to have one generalized design that could provide multiple different logic gates or states for a targeted use. In pursuit of this goal, we demonstrate a switchable, triangular dye-labeled three-arm DNA scaffold where the individual arms can be assembled in different combinations and the linkage between each arm can be physically removed using toehold-mediated strand displacement and then replaced by a rapid anneal. Rearranging this core structure alters the rates of Förster resonance energy transfer (FRET) between each of the two or three pendant dyes giving rise to a rich library of unique spectral signatures that ultimately form the basis for molecular photonic logic gates. The DNA scaffold is designed such that different linker lengths joining each arm, and which are used as the inputs here, can also be used independently of one another thus enhancing the range of molecular gates. The functionality of this platform structure is highlighted by easily configuring it into a series of one-, two- and three-input photonic Boolean logic gates such as OR, AND, INHIBIT, etc., along with a photonic keypad lock. Different gates can be realized in the same structure by altering which dyes are interrogated and implementation of toehold-mediated strand displacement and/or annealing allows reconfigurable switching between input states within a single logic gate as well as between two different gating devices

    Virtual Coaching and Deliberate Practice to Enhance Medical Students\u27 Clinical Reasoning during Oral Case Presentations

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    ABSTRACT: Introduction Oral case presentations (OP) provide an opportunity for medical students to practice clinical reasoning and communication skills, and for faculty to provide assessment. Specific teaching strategies are needed to improve students’ OP skills. Objective To compare the effectiveness of Virtual Coaching (VC) to Small Group (SG) discussion or Traditional Feedback (TF/control) in improving clinical reasoning during OP, using a validated PBEAR (Problem Representation, Background Evidence, Analysis, Recommendation) tool. Design/Methods Students from two medical schools were randomly assigned to three groups during their inpatient pediatric clerkship. All completed an eLearning module about using illness scripts to promote clinical reasoning and presenting in the PBEAR format. TF/control students completed online “Aquifer” cases; VC students recorded abstracted data from the same cases with on-line faculty feedback and self-reflection; SG students attended faculty facilitated discussions of the same cases. Students were video recorded presenting pre- and post-curriculum cases. Reviewers blinded to assignment groups rated pre and post videos with the PBEAR OP tool. Results The overall score and sub-scale scores improved for all groups. VC students significantly improved in the Analysis subscale compared to SG or controls. Students rated the SG teaching sessions as more enjoyable and effective in improving their clinical reasoning and presentation skills. Conclusions A blended learning curriculum using VC significantly improved students’ clinical reasoning as assessed by the Analysis subscale
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