1,377 research outputs found

    From bench to bedside: Tracing the payback forwards from basic or early clinical research – A preliminary exercise and proposals for a future study

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    EXECUTIVE SUMMARY Chapter 1 : Introduction • The members of the research team from HERG and the Wellcome Trust have conducted previous studies showing that it is possible both to assess the payback from applied health research, and to use bibliometrics to trace the links between generations of research and clinical guidelines. In another of the team’s studies, however, it proved difficult to replicate the major study by Comroe and Dripps (1976) that had identified clinical advances and then worked backwards to show that they had relied on earlier basic research. Therefore, the study reported here sets out to use the methods developed in our previous studies of payback to undertake analysis that starts with more basic or early clinical research and traces the research lines forwards to clinical applications. Whilst this preliminary study involved preparation for a future large-scale study, it was hoped that it would also provide an interesting case study. • Starting with the research outputs of one team 20 years ago, called the 1st generation papers, the preliminary study has three main elements: standard bibliometric analysis through several generations of papers; categorisation of the citations; and qualitative analysis using questionnaires, critical pathway analysis and interviews to trace the impact of the 1st generation of research. • Diabetes and cardiology were suggested as possible topics on which to base the study. Initial reviews identified two bodies of research in diabetes as being potentially suitable for reasons such as the continuing activity of key members of the team. • The research into diabetes conducted in 1981 by George Alberti and his team at Newcastle, and collaborators elsewhere, was selected to provide the case study for this preliminary stage for several reasons. It was thought to have been important science and there was a belief that some of it had made a contribution to clinical practice. Chapter 2 : Bibliometric analysis • An original plan to look at publications produced over a three year period was changed to looking at the output of just one year, 1981, because in that year alone Alberti and colleagues published 29 articles. These form the 1st generation papers and the average number of citations they received is high. Identifying the citations given to these 29 papers resulted in 799 2nd generation papers and 12,891 3rd generation papers. The numbers involved meant that it was impractical to go beyond the 3rd generation. Within the high overall average, the variation in the number of citations per paper was iii considerable going from 76 to just one. Similarly, the half-lives of the 29 papers, ie the time taken for an article to receive 50% of its citations, ranged from two years to 11. • Articles can be given a Research Level (ie one of four levels from clinical observation to basic) based on the journals in which they appear. Such analysis demonstrates the breadth of Alberti’s work because the 29 articles are spread across all four Research Levels. Crucially, there was not a shift from basic to more clinical levels across the generations. The higher than average number of authors and addresses per paper is testimony to Alberti’s extensive collaborations. • The funding acknowledgements reveal the high proportion of papers supported, at least partially, by one funder: the British Diabetic Association, now Diabetes UK, which provided core support for Alberti’s Newcastle team. Chapter 3 : Categorisation of citations • Traditional citation analysis does not allow identification of the importance of the cited article to the citing article, and therefore limits the ability to use citation analysis to trace the impact of basic or early research on later research. We conducted a review of the literature of the meaning of citations. • From this review, a template was devised that allowed the location, nature and importance of citations to be recorded as well as the type of research (basic or clinical) described in the paper. This was used by six assessors on a sample of papers and inter-rater reliability was tested. Further work is required to refine the template and its definitions, and to improve its consistency in application. • Nevertheless, for initial analysis, it was applied to 623 out of the 799 2nd generation papers. A four point scale was used for the importance of the cited paper to the citing paper. In just 9% of cases was the cited 1st generation paper thought to be in one of the top two categories, ie of Considerable or Essential importance to the citing paper. • Statistical analysis revealed no relationship between the number of citations a paper received and the proportion of citations where the cited paper was classified as being of high (ie. Considerable or Essential) importance to the citing paper. Self-citations, however, were shown to be significantly more likely to be in this category. • The classification of the type of research (basic or clinical) by our analysis of each paper broadly agreed with the classification of the journals by Research Level. • The time constraints involved in applying the template, plus the lack of any overall pattern in terms of correlations between number and importance of citations, might point to the desirability of adopting a more selective approach, guided by qualitative analysis. In any selective approach, however, it is likely that self-citations should feature. iv Chapter 4 : Qualitative analysis • Given the number of co-authors, it seemed appropriate to send them a questionnaire rather than attempt to interview them. Therefore the interviewing was rather more concentrated than originally intended. Only one formal critical pathway was created, but it was undertaken by an expert in the field who worked with Alberti at Newcastle. • Some problems emerged in taking 1981 as the starting point for the study. Alberti identified 10 selected papers from the 1970s and 1980s that he felt had had most impact on clinical practice. These helped to give us both a better understanding of the payback from our 1st generation, or 1981, papers, and provided further material for analysis. • Attempting to describe the impact from the 1981 body of work, and from the 10 selected papers, underlines the complex reality of how science advances and influences clinical practice. If they make a contribution at all, most studies make a small, incremental one. • A few papers, however, have been shown to have a considerably greater impact. A possible key to the level of payback indicated is the enormous breadth of Alberti’s contacts, and fields and methods of working, to which various references were made. This is well illustrated in the account of how the idea for subcutaneous pumps came about. Similarly, the ability to produce the very important guidelines on treating diabetics during surgery, and diabetic coma, partly resulted from the application to clinical problems of the understandings gained from some of the basic/early clinical studies. It is significant that the key papers on these issues, all of which come from the list of 10 selected papers from the 1970s and 1980s, were having an impact on the 1981 work. • How far the collection of papers from 1981 have been drawn upon in similar ways is less clear. Nevertheless, papers on treating diabetics during open heart surgery, and on bolus delivery of insulin at meal times, were key parts of these wider streams, despite variable citation levels. Furthermore, various papers, including on acarbose, on portal infusion of insulin, and on semi-human insulin, were important steps in bodies of work in their respective areas. The complexity was illustrated by a paper that helped debunk the Chlorpropamide alcohol flushing hypothesis, and thus end a line of scientific enquiry: there was payback in stopping an incorrect line of inquiry, but nothing on which to build. • Each technique in the qualitative study produced information about the successful subsequent careers followed by many researchers trained through working with Alberti. • Historical perspectives, and insider expert opinions, were important in the qualitative analysis. Overall, the qualitative methods highlighted some limitations in the bibliometric approach but also showed how aspects of the citation analysis can complement the opinions expressed, for example about the importance of the breadth of Alberti’s work. v Chapter 5 : Lessons learnt and the way forward • Lessons learnt: a variety of methods can be used successfully to gather considerable data about the payback from a body of research undertaken 20 years ago. Traditional citation analysis alone, however, is not sufficient: the importance of the surgery papers despite their relatively low citation rates illustrates this. The qualitative methods are important and much of the analysis is strengthened by drawing on multiple approaches. Several problems remain, including: identifying a coherent starting point for the analysis; coping with the enormous number of papers involved in later generations; and refining the template for categorising citations and developing ways of fully utilising the results from applying it. • Preparing for the large-scale study: this preliminary study provides a basis on which to attempt to undertake the larger study we envisaged. Issues now being addressed include identification of the level of bibliometric/citation analysis necessary to complement any qualitative studies. To provide confidence in the findings from an eventual large-scale study, we will need to expand the focus. The study will need to cover at least four sets of case studies. Ideally, each set should focus on a number of research groups working in a country in the same field. We hope there will be sets of case studies in two or three fields and in at least two countries. The issues to be explored will include ones highlighted by this study such as breadth of work, level of collaboration, and the role of core funding. • Methods for the large-scale study: for each case study we now propose to employ two methodological elements based on the qualitative and quantitative techniques adopted in the preliminary study. They will work in parallel but the quantitative bibliometric analysis would be applied selectively to parts of ‘research lines’ (ie discrete themes of research) identified in the qualitative studies as being important in influencing clinical practice. • Presenting the findings: each research line could be written-up in a standardised document that would use the HERG payback model and categories to describe the impact of that research. We shall use the qualitative and quantitative data to compare and contrast the ‘payback’ of research lines by country and disease, and then identify common factors that correlate with the translation of basic or early clinical research. • Concluding comments: in the era of ‘evidence based policy’, research funders are looking for value for money in the research they support and for evidence on the effectiveness of different research strategies. In this study we have begun developing a methodology that will allow us to understand the complexity of research development over a series of generations. The utility of the policy research we propose here will only be realised when it is scaled up to cover a number of different fields in different settings.NHS Executive, London Regio

    The interaction of Trypanosoma congolense with endothelial cells

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    Factors which affect adhesion of cultured Trypanosoma congolense bloodstream forms to mammalian feeder cells have been examined. Using an in vitro binding assay, the initial events following interaction of trypanosomes with bovine aorta endothelial (BAE) cells were monitored by both light- and electron microscopy. Metabolic inhibitors and other biochemicals were incubated with either cells or parasites, to test whether any inhibited the process. Our findings suggest that adhesion of the parasites is an active process requiring metabolic energy from the trypanosomes, but not from endothelial cells. We also provide data suggesting that T. congolense bloodstream forms possess a lectin-like domain, localized at distinct sites on their flagellar surface, which interacts with specific carbohydrate receptors, most likely sialic acid residues, on the endothelial cell plasma membrane. We also suggest that the cytoskeletal protein actin is probably involved in this interactio

    FAK acts as a suppressor of RTK-MAP kinase signalling in Drosophila melanogaster epithelia and human cancer cells

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    Receptor Tyrosine Kinases (RTKs) and Focal Adhesion Kinase (FAK) regulate multiple signalling pathways, including mitogen-activated protein (MAP) kinase pathway. FAK interacts with several RTKs but little is known about how FAK regulates their downstream signalling. Here we investigated how FAK regulates signalling resulting from the overexpression of the RTKs RET and EGFR. FAK suppressed RTKs signalling in Drosophila melanogaster epithelia by impairing MAPK pathway. This regulation was also observed in MDA-MB-231 human breast cancer cells, suggesting it is a conserved phenomenon in humans. Mechanistically, FAK reduced receptor recycling into the plasma membrane, which resulted in lower MAPK activation. Conversely, increasing the membrane pool of the receptor increased MAPK pathway signalling. FAK is widely considered as a therapeutic target in cancer biology; however, it also has tumour suppressor properties in some contexts. Therefore, the FAK-mediated negative regulation of RTK/MAPK signalling described here may have potential implications in the designing of therapy strategies for RTK-driven tumours

    Projective dynamics and first integrals

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    We present the theory of tensors with Young tableau symmetry as an efficient computational tool in dealing with the polynomial first integrals of a natural system in classical mechanics. We relate a special kind of such first integrals, already studied by Lundmark, to Beltrami's theorem about projectively flat Riemannian manifolds. We set the ground for a new and simple theory of the integrable systems having only quadratic first integrals. This theory begins with two centered quadrics related by central projection, each quadric being a model of a space of constant curvature. Finally, we present an extension of these models to the case of degenerate quadratic forms.Comment: 39 pages, 2 figure

    Energy cost and return for hunting in African wild dogs and Cheetahs

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    African wild dogs (Lycaon pictus) are reported to hunt with energetically costly long chase distances. We used high-resolution GPS and inertial technology to record 1,119 high-speed chases of all members of a pack of six adult African wild dogs in northern Botswana. Dogs performed multiple short, high-speed, mostly unsuccessful chases to capture prey, while cheetahs (Acinonyx jubatus) undertook even shorter, higher-speed hunts. We used an energy balance model to show that the energy return from group hunting and feeding substantially outweighs the cost of multiple short chases, which indicates that African wild dogs are more energetically robust than previously believed. Comparison with cheetah illustrates the trade-off between sheer athleticism and high individual kill rate characteristic of cheetahs, and the energetic robustness of frequent opportunistic group hunting and feeding by African wild dogs

    Basin-scale inputs of cobalt, iron, and manganese from the Benguela-Angola front to the South Atlantic Ocean

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    Author Posting. © Association for the Sciences of Limnology and Oceanography, 2012. This article is posted here by permission of Association for the Sciences of Limnology and Oceanography for personal use, not for redistribution. The definitive version was published in Limnology and Oceanography 57 (2012): 989-1010, doi:10.4319/lo.2012.57.4.0989.We present full-depth zonal sections of total dissolved cobalt, iron, manganese, and labile cobalt from the South Atlantic Ocean. A basin-scale plume from the African coast appeared to be a major source of dissolved metals to this region, with high cobalt concentrations in the oxygen minimum zone of the Angola Dome and extending 2500 km into the subtropical gyre. Metal concentrations were elevated along the coastal shelf, likely due to reductive dissolution and resuspension of particulate matter. Linear relationships between cobalt, N2O, and O2, as well as low surface aluminum supported a coastal rather than atmospheric cobalt source. Lateral advection coupled with upwelling, biological uptake, and remineralization delivered these metals to the basin, as evident in two zonal transects with distinct physical processes that exhibited different metal distributions. Scavenging rates within the coastal plume differed for the three metals; iron was removed fastest, manganese removal was 2.5 times slower, and cobalt scavenging could not be discerned from water mass mixing. Because scavenging, biological utilization, and export constantly deplete the oceanic inventories of these three hybrid-type metals, point sources of the scale observed here likely serve as vital drivers of their oceanic cycles. Manganese concentrations were elevated in surface waters across the basin, likely due to coupled redox processes acting to concentrate the dissolved species there. These observations of basin-scale hybrid metal plumes combined with the recent projections of expanding oxygen minimum zones suggest a potential mechanism for effects on ocean primary production and nitrogen fixation via increases in trace metal source inputs.This research was supported US National Science Foundation Chemical Oceanography (Division of Ocean Sciences OCE-0452883, OCE-0752291, OCE-0928414, OCE-1031271), the Center for Microbial Research and Education, the Gordon and Betty Moore Foundation, the WHOI Coastal Ocean Institute, and the WHOI Ocean Life Institute

    Measurement of the Total Active 8B Solar Neutrino Flux at the Sudbury Neutrino Observatory with Enhanced Neutral Current Sensitivity

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    The Sudbury Neutrino Observatory (SNO) has precisely determined the total active (nu_x) 8B solar neutrino flux without assumptions about the energy dependence of the nu_e survival probability. The measurements were made with dissolved NaCl in the heavy water to enhance the sensitivity and signature for neutral-current interactions. The flux is found to be 5.21 +/- 0.27 (stat) +/- 0.38 (syst) x10^6 cm^{-2}s^{-1}, in agreement with previous measurements and standard solar models. A global analysis of these and other solar and reactor neutrino results yields Delta m^{2} = 7.1^{+1.2}_{-0.6}x10^{-5} ev^2 and theta = 32.5^{+2.4}_{-2.3} degrees. Maximal mixing is rejected at the equivalent of 5.4 standard deviations.Comment: Submitted to Phys. Rev. Let

    Second Generation Leptoquark Search in p\bar{p} Collisions at s\sqrt{s} = 1.8 TeV

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    We report on a search for second generation leptoquarks with the D\O\ detector at the Fermilab Tevatron ppˉp\bar{p} collider at s\sqrt{s} = 1.8 TeV. This search is based on 12.7 pb1^{-1} of data. Second generation leptoquarks are assumed to be produced in pairs and to decay into a muon and quark with branching ratio β\beta or to neutrino and quark with branching ratio (1β)(1-\beta). We obtain cross section times branching ratio limits as a function of leptoquark mass and set a lower limit on the leptoquark mass of 111 GeV/c2^{2} for β=1\beta = 1 and 89 GeV/c2^{2} for β=0.5\beta = 0.5 at the 95%\ confidence level.Comment: 18 pages, FERMILAB-PUB-95/185-

    Anti-cancer effects and mechanism of actions of aspirin analogues in the treatment of glioma cancer

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    INTRODUCTION: In the past 25 years only modest advancements in glioma treatment have been made, with patient prognosis and median survival time following diagnosis only increasing from 3 to 7 months. A substantial body of clinical and preclinical evidence has suggested a role for aspirin in the treatment of cancer with multiple mechanisms of action proposed including COX 2 inhibition, down regulation of EGFR expression, and NF-κB signaling affecting Bcl-2 expression. However, with serious side effects such as stroke and gastrointestinal bleeding, aspirin analogues with improved potency and side effect profiles are being developed. METHOD: Effects on cell viability following 24 hr incubation of four aspirin derivatives (PN508, 517, 526 and 529) were compared to cisplatin, aspirin and di-aspirin in four glioma cell lines (U87 MG, SVG P12, GOS – 3, and 1321N1), using the PrestoBlue assay, establishing IC50 and examining the time course of drug effects. RESULTS: All compounds were found to decrease cell viability in a concentration and time dependant manner. Significantly, the analogue PN517 (IC50 2mM) showed approximately a twofold increase in potency when compared to aspirin (3.7mM) and cisplatin (4.3mM) in U87 cells, with similar increased potency in SVG P12 cells. Other analogues demonstrated similar potency to aspirin and cisplatin. CONCLUSION: These results support the further development and characterization of novel NSAID derivatives for the treatment of glioma

    Cervical cancer screening: target age bracket, screening frequency and screening method: review of recent evidence and comparison with the Portuguese performance indicator

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    Esta revisão teve por objetivo avaliar a força de evidência do indicador de desempenho português relativo ao rastreio do Câncer do Colo do Útero (CCU): (1) limites etários das mulheres da população geral que o devem realizar, a (2) periodicidade com que deve ser realizado e (3) qual o melhor exame de rastreio. Foram pesquisados os seguintes termos MeSH: vaginal smears, age groups, periodicity, methods, uterine cervical cancer. Foram excluídos os artigos que não abordavam o objetivo da investigação ou que não fossem redigidos em Inglês, Português ou Espanhol. Para interpretar os artigos selecionados foi utilizada a classificação SORT. Foram encontrados 197 artigos, dos quais seleccionados 9: 1 revisão sistemática (RS), 1 estudo clínico controlado aleatorizado, 2 estudos observacionais retrospectivos e 5 normas de orientação clínica (NOC). Os autores optaram por incluir nesta revisão mais 4 NOCs e 2 RSs por considerarem ser relevantes para a população Portuguesa, apesar de não resultarem da pesquisa efectuada. Os estudos sugerem realização do rastreio entre os 21 e 25 até aos 65 anos, com uma periodicidade trienal usando a citologia convencional. Existe ainda controvérsia no que toca aos 3 objetivos deste artigo (limites etários, frequência e método).The scope of this review was to assess the strength of evidence of Portuguese performance indicators on Cervical Cancer screening: (1) age group of the women that should be screened for cervical cancer; (2) frequency of screening; and (3) the best method for screening. The following MeSH terms were searched: vaginal smears, age groups, periodicity, methods, uterine cervical cancer. Articles not reflecting the study objectives or not available in English, Portuguese or Spanish were excluded. The SORT classification was used to rate the articles selected.Of the 197 articles found, 9 that met all study criteria were selected for inclusion in this review. These included 1 systematic review, 1 randomized controlled clinical trial, 2 retrospective studies and 5 clinical guidelines. The authors also chose to include 4 clinical guidelines and two systematic reviews relevant to the Portuguese population even though they did not appear in the initial search of the literature. The studies suggest screening women between the ages of 21 to 25 years and 65 years of age, once every three years using conventional cytology. There is still controversy regarding the three objectives of this study (target age bracket, screening frequency and screening method)
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