1,229 research outputs found

    Carcinoma-associated fibroblasts stimulate tumor progression of initiated human epithelium

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    The present study demonstrates that fibroblasts associated with carcinomas stimulate tumor progression of initiated nontumorigenic epithelial cells both in an in vivo tissue recombination system and in an in vitro coculture system. Human prostatic carcinoma-associated fibroblasts grown with initiated human prostatic epithelial cells dramatically stimulated growth and altered histology of the epithelial population. This effect was not detected when normal prostatic fibroblasts were grown with the initiated epithelial cells under the same experimental conditions. In contrast, carcinoma-associated fibroblasts did not affect growth of normal human prostatic epithelial cells under identical conditions. From these data, we conclude that in this human prostate cancer model, carcinoma-associated fibroblasts stimulate progression of tumorigenesis. Thus, carcinoma-associated fibroblasts can direct tumor progression of an initiated prostate epithelial cell

    Study Effort and Student Success: A MOOC Case Study

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    Learning was once defined as the function of efforts spent in relation to efforts needed [3]. Provided that effort is closely linked to time, previous research has found a positive relationship between student effort over time and student success, both in university education and Massive Open Online Courses (MOOCs). With the complex environment of tracing and identifying relevant data of student learning processes in MOOCs, this study employs learning analytics to examine this relationship for MITx 6.00x, an introductory programming and computer science MOOC hosted on the edX MOOC platform. A population sample from the MOOC (N = 32,621) was examined using logistic regression, controlling for variables that may also influence the outcome. Conversely, the outcome of this research study suggests that there is a curvilinear relationship between effort over time and student success, meaning those who exert effort for the longest amount of time in the MOOC actually have a lower probability of obtaining a certificate than others who exert effort over somewhat less time. Finally, research implications are discussed.acceptedVersio

    Low cognitive ability in early adulthood is associated with reduced lung function in middle age: the Vietnam Experience Study

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    Objective Reduced lung function has been linked to poorer cognitive ability later in life. In the present study, the authors examined the converse: whether there was a prospective association between cognitive ability in early adulthood and lung function in middle age.Methods Participants were 4256 male Vietnam-era US veterans. Cognitive ability was assessed by the Army General Technical Test on enlistment when participants were, on average, 20 years old (range: 17-34). Data on ethnicity and place of service were extracted from army files. Smoking behaviour, alcohol consumption, basic socio-demographics and whether participants had a physician-diagnosed chronic disease were determined by telephonic interview in middle age in 1985. Forced expiratory volume in one second (FEV1) was measured by spirometry at a 3-day medical examination in 1986. Height and weight were also measured.Results In linear regression models, poor cognitive ability in early adulthood was associated with reduced lung function in middle age, first adjusting for age and height, beta=0.17, p<0.001, then additionally adjusting for circumstantial, socio-demographic, lifestyle and health factors, beta=0.12, p=0.001. The same results were obtained when the analysis was confined to nonsmokers.Conclusion Not only is lung function related to subsequent cognitive ability, but poor cognitive ability earlier in life is also associated with reduced lung function in middle age

    Cortisol, dehydroepiandrosterone sulphate, their ratio and hypertension: evidence of associations in male veterans from the Vietnam Experience Study.

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    Although clinical observations implicate cortisol in hypertension, the epidemiological evidence is less compelling. Little is known about the relationship between dehydroepiandrosterone sulphate (DHEAS) and hypertension, and nothing about the association with the cortisol: DHEAS ratio. The present analyses of data obtained from Vietnamera US veterans examined the associations between cortisol, DHEAS, their ratio and hypertension. Participants were 4180 male veterans. From military files, telephone interviews and a medical examination, sociodemographic and health data were collected. At medical examination, a fasted morning blood sample was collected to assay serum cortisol and DHEAS, blood pressure measured and body mass index (BMI) determined. Hypertension was defined by having one of the following: a reported physician diagnosis, taking antihypertensive medication, an average systolic blood pressure >= 140 mm Hg and an average diastolic blood pressure >= 90 mm Hg. Cortisol and the cortisol: DHEAS ratio were positively associated with hypertension (P < 0.001), whereas DHEAS was negatively associated; the latter relationship was attenuated to non-significance (P = 0.06) in models that adjusted for age, sociodemographics, place of service, health behaviours and BMI. The present analyses provide confirmation of a positive association between cortisol and the cortisol: DHEAS ratio and population hypertension. Journal of Human Hypertension (2011) 25, 418-424; doi:10.1038/jhh.2011.6; published online 10 February 201

    Glauber theory of initial- and final-state interactions in (p,2p) scattering

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    We develop the Glauber theory description of initial- and final-state interactions (IFSI) in quasielastic A(p,2p) scattering. We study the IFSI-distortion effects both for the inclusive and exclusive conditions. In inclusive reaction the important new effect is an interaction between the two sets of the trajectories which enter the calculation of IFSI-distorted one-body density matrix for inclusive (p,2p) scattering and are connected with incoherent elastic rescatterings of the initial and final protons on spectator nucleons. We demonstrate that IFSI-distortions of the missing momentum distribution are large over the whole range of missing momentum both for inclusive and exclusive reactions and affect in a crucial way the interpretation of the BNL data on (p,2p) scattering. Our numerical results show that in the region of missing momentum p_{m}\lsim 100-150 MeV/c the incoherent IFSI increase nuclear transparency by 5-10\%. The incoherent IFSI become dominant at p_{m}\gsim 200 MeV/c.Comment: Accepted in Z. Phys.A, Latex, 26 pages, uuencoded 9 figure

    On reminder effects, drop-outs and dominance: evidence from an online experiment on charitable giving

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    We present the results of an experiment that (a) shows the usefulness of screening out drop-outs and (b) tests whether different methods of payment and reminder intervals affect charitable giving. Following a lab session, participants could make online donations to charity for a total duration of three months. Our procedure justifying the exclusion of drop-outs consists in requiring participants to collect payments in person flexibly and as known in advance and as highlighted to them later. Our interpretation is that participants who failed to collect their positive payments under these circumstances are likely not to satisfy dominance. If we restrict the sample to subjects who did not drop out, but not otherwise, reminders significantly increase the overall amount of charitable giving. We also find that weekly reminders are no more effective than monthly reminders in increasing charitable giving, and that, in our three months duration experiment, standing orders do not increase giving relative to one-off donations

    The realistic performance achievable with mycobacterial automated culture systems in high and low prevalence settings

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    <p>Abstract</p> <p>Background</p> <p>Diagnostic tests are generally used in situations with similar pre-test probability of disease to where they were developed. When these tests are applied in situations with very different pre-test probabilities of disease, it is informative to model the likely implications of known characteristics of test performance in the new situation. This is the case for automated <it>Mycobacterium tuberculosis </it>(MTB) liquid culture systems for tuberculosis case detection which were developed and are widely used in low burden settings but are only beginning to be applied on a large scale in high burden settings.</p> <p>Methods</p> <p>Here we model the performance of MTB liquid culture systems in high and low tuberculosis (TB) prevalence settings using detailed published data concentrating on the likely frequency of cross-contamination events.</p> <p>Results</p> <p>Our model predicts that as the TB prevalence in the suspect population increases there is an exponential increase in the risk of MTB cross-contamination events expected in otherwise negative samples, even with equivalent technical performance of the laboratories. Quality control and strict cross-contamination measures become increasingly critical as the burden of MTB infection among TB suspects increases. Even under optimal conditions the realistically achievable specificity of these systems in high burden settings will likely be significantly below that obtained in low TB burden laboratories.</p> <p>Conclusions</p> <p>Liquid culture systems can play a valuable role in TB case detection in laboratories in high burden settings, but laboratory workers, policy makers and clinicians should be aware of the increased risks, independent of laboratory proficiency, of cross-contamination events in high burden settings.</p

    Identification of potential therapeutic targets in prostate cancer through a cross-species approach.

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    Genetically engineered mouse models of cancer can be used to filter genome-wide expression datasets generated from human tumours and to identify gene expression alterations that are functionally important to cancer development and progression. In this study, we have generated RNAseq data from tumours arising in two established mouse models of prostate cancer, PB-Cre/PtenloxP/loxP and p53loxP/loxPRbloxP/loxP, and integrated this with published human prostate cancer expression data to pinpoint cancer-associated gene expression changes that are conserved between the two species. To identify potential therapeutic targets, we then filtered this information for genes that are either known or predicted to be druggable. Using this approach, we revealed a functional role for the kinase MELK as a driver and potential therapeutic target in prostate cancer. We found that MELK expression was required for cell survival, affected the expression of genes associated with prostate cancer progression and was associated with biochemical recurrence

    The emerging structure of the Extended Evolutionary Synthesis: where does Evo-Devo fit in?

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    The Extended Evolutionary Synthesis (EES) debate is gaining ground in contemporary evolutionary biology. In parallel, a number of philosophical standpoints have emerged in an attempt to clarify what exactly is represented by the EES. For Massimo Pigliucci, we are in the wake of the newest instantiation of a persisting Kuhnian paradigm; in contrast, Telmo Pievani has contended that the transition to an EES could be best represented as a progressive reformation of a prior Lakatosian scientific research program, with the extension of its Neo-Darwinian core and the addition of a brand-new protective belt of assumptions and auxiliary hypotheses. Here, we argue that those philosophical vantage points are not the only ways to interpret what current proposals to ‘extend’ the Modern Synthesis-derived ‘standard evolutionary theory’ (SET) entail in terms of theoretical change in evolutionary biology. We specifically propose the image of the emergent EES as a vast network of models and interweaved representations that, instantiated in diverse practices, are connected and related in multiple ways. Under that assumption, the EES could be articulated around a paraconsistent network of evolutionary theories (including some elements of the SET), as well as models, practices and representation systems of contemporary evolutionary biology, with edges and nodes that change their position and centrality as a consequence of the co-construction and stabilization of facts and historical discussions revolving around the epistemic goals of this area of the life sciences. We then critically examine the purported structure of the EES—published by Laland and collaborators in 2015—in light of our own network-based proposal. Finally, we consider which epistemic units of Evo-Devo are present or still missing from the EES, in preparation for further analyses of the topic of explanatory integration in this conceptual framework
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