Radio-Frequency Safety Assessment of Stents in Blood Vessels During Magnetic Resonance Imaging

Purpose: The purpose of this study was to investigate the need for high-resolution detailed anatomical modeling to correctly estimate radio-frequency (RF) safety during magnetic resonance imaging (MRI). RF-induced heating near metallic implanted devices depends on the electric field tangential to the device (Etan). Etan and specific absorption rate (SAR) were analyzed in blood vessels of an anatomical model to understand if a standard gel phantom accurately represents the potential heating in tissues due to passive vascular implants such as stents.Methods: A numerical model of an RF birdcage body coil and an anatomically realistic virtual patient with a native spatial resolution of 1 mm3 were used to simulate the in vivo electric field at 64 MHz (1.5 T MRI system). Maximum values of SAR inside the blood vessels were calculated and compared with peaks in a numerical model of the ASTM gel phantom to see if the results from the simplified and homogeneous gel phantom were comparable to the results from the anatomical model. Etan values were also calculated in selected stent trajectories inside blood vessels and compared with the ASTM result.Results: Peak SAR values in blood vessels were up to ten times higher than those found in the ASTM standard gel phantom. Peaks were found in clinically significant anatomical locations, where stents are implanted as per intended use. Furthermore, Etan results showed that volume-averaged SAR values might not be sufficient to assess RF safety.Conclusion: Computational modeling with a high-resolution anatomical model indicated higher values of the incident electric field compared to the standard testing approach. Further investigation will help develop a robust safety testing method which reflects clinically realistic conditions

Arguably big biology: Sociology, spatiality and the knockout mouse project

© 2013 copyright Palgrave MacmillanThis is a post-peer-review, pre-copyedit version of an article published in BioSocieties. The definitive publisher-authenticated version BioSocieties, 2013, Vol. 8, pp. 417-431 is available online at: http://www.palgrave-journals.com/biosoc/journal/v8/n4/full/biosoc201325a.htmlFollowing the completion of the Human Genome Project (HGP), a critical challenge has been how to make biological sense of the amassed sequence data and translate this into clinical applications. A range of large biological research projects, as well as more distributed experimental collaborations, are seeking to realise this through translational research initiatives and postgenomic approaches. Drawing on interviews with key participants, this article explores the biological assumptions, sociological challenges and spatial imaginaries at play in arguments around one of these developments, which is using genetically altered mice to understand gene function. The knockout mouse project (KOMP) is a large-scale initiative in functional genomics, seeking to produce a ‘knockout mouse’ for each gene in the mouse’s genome, which can then be used to answer questions about gene function in mammals. KOMP is frequently framed as one successor to the HGP, emblematic of the ambitions of internationally coordinated biological research. However, the development of new technologies for generating and managing genetically altered mice, alongside the challenge of asking biologically meaningful questions of vast numbers of animals, is creating new frictions in this extension and intensification of biological research practices. This article introduces two separate approaches to the future of international research using mutant mice as stakeholders to negotiate the biological, sociological and spatial challenges of collaboration. The first centres on the directed research practices and sociological assumptions of KOMP, as individual researchers are reorganised around shared animals, databases and infrastructures. The second highlights an alternative vision of the future of biomedical research, using distributed management to enhance the sensitivities and efficiencies of existing experimental practices over space. These exemplify two different tactics in the organisation of an ‘arguably’ big biology. They also critically embody different sociological and spatial imaginaries for the collaborative practices of international translational research

Governing stem cell therapy in India: regulatory vacuum or jurisdictional ambiguity?

Stem cell treatments are being offered in Indian clinics although preclinical evidence of their efficacy and safety is lacking. This is attributed to a governance vacuum created by the lack of legally binding research guidelines. By contrast, this paper highlights jurisdictional ambiguities arising from trying to regulate stem cell therapy under the auspices of research guidelines when treatments are offered in a private market disconnected from clinical trials. While statutory laws have been strengthened in 2014, prospects for their implementation remain weak, given embedded challenges of putting healthcare laws and professional codes into practice. Finally, attending to the capacities of consumer law and civil society activism to remedy the problem of unregulated treatments, the paper finds that the very definition of a governance vacuum needs to be reframed to clarify whose rights to health care are threatened by the proliferation of commercial treatments and individualized negligence-based remedies for grievances

Profitable failure: antidepressant drugs and the triumph of flawed experiments

Drawing on an analysis of Irving Kirsch and colleagues? controversial 2008 article in PLoS [Public Library of Science] Medicine on the efficacy of SSRI antidepressant drugs such as Prozac, I examine flaws within the methodologies of randomized controlled trials (RCTs) that have made it difficult for regulators, clinicians and patients to determine the therapeutic value of this class of drug. I then argue, drawing analogies to work by Pierre Bourdieu and Michael Power, that it is the very limitations of RCTs ? their inadequacies in producing reliable evidence of clinical effects ? that help to strengthen assumptions of their superiority as methodological tools. Finally, I suggest that the case of RCTs helps to explore the question of why failure is often useful in consolidating the authority of those who have presided over that failure, and why systems widely recognized to be ineffective tend to assume greater authority at the very moment when people speak of their malfunction

Bigger, Faster, Better? Rhetorics and Practices of Large-Scale Research in Contemporary Bioscience

publication-status: Publishedtypes: ArticleEditorial for Special Issu

Pecking order theory versus trade-off theory : are service SMEs’ capital structure decisions different?

This paper seeks to analyse if the capital structure decisions of service small and medium-sized enterprises (SMEs) are different from those of other types of firm. To do so, we consider four research samples: (i) 610 service SMEs; (ii) 126 service large firms; (iii) 679 manufacturing and construction SMEs; and (iv) 132 manufacturing and construction large firms. Using the two-step estimation method, the empirical evidence obtained in this study shows that the capital structure decisions of service SMEs are different from those of other types of firm. Service SMEs’ capital structure decisions are closer to the assumptions of Pecking Order Theory and further removed from those of Trade-Off Theory compared with the case of other types of firm

Captivating behaviour: mouse models, experimental genetics and reductionist returns in the neurosciences

This a post-print, author-produced version of an article accepted for publication in The Sociological Review. Copyright © 2010 Wiley Blackwell. The definitive version is available at www3.interscience.wiley.comNo Abstract availabl

Bioprospecting the African Renaissance: The new value of muthi in South Africa

This article gives an overview of anthropological research on bioprospecting in general and of available literature related to bioprospecting particularly in South Africa. It points out how new insights on value regimes concerning plant-based medicines may be gained through further research and is meant to contribute to a critical discussion about the ethics of Access and Benefit Sharing (ABS). In South Africa, traditional healers, plant gatherers, petty traders, researchers and private investors are assembled around the issues of standardization and commercialization of knowledge about plants. This coincides with a nation-building project which promotes the revitalization of local knowledge within the so called African Renaissance. A social science analysis of the transformation of so called Traditional Medicine (TM) may shed light onto this renaissance by tracing social arenas in which different regimes of value are brought into conflict. When medicinal plants turn into assets in a national and global economy, they seem to be manipulated and transformed in relation to their capacity to promote health, their market value, and their potential to construct new ethics of development. In this context, the translation of socially and culturally situated local knowledge about muthi into global pharmaceuticals creates new forms of agency as well as new power differentials between the different actors involved

Hyperpolarized 13C MRI: Path to Clinical Translation in Oncology.

This white paper discusses prospects for advancing hyperpolarization technology to better understand cancer metabolism, identify current obstacles to HP (hyperpolarized) 13C magnetic resonance imaging's (MRI's) widespread clinical use, and provide recommendations for overcoming them. Since the publication of the first NIH white paper on hyperpolarized 13C MRI in 2011, preclinical studies involving [1-13C]pyruvate as well a number of other 13C labeled metabolic substrates have demonstrated this technology's capacity to provide unique metabolic information. A dose-ranging study of HP [1-13C]pyruvate in patients with prostate cancer established safety and feasibility of this technique. Additional studies are ongoing in prostate, brain, breast, liver, cervical, and ovarian cancer. Technology for generating and delivering hyperpolarized agents has evolved, and new MR data acquisition sequences and improved MRI hardware have been developed. It will be important to continue investigation and development of existing and new probes in animal models. Improved polarization technology, efficient radiofrequency coils, and reliable pulse sequences are all important objectives to enable exploration of the technology in healthy control subjects and patient populations. It will be critical to determine how HP 13C MRI might fill existing needs in current clinical research and practice, and complement existing metabolic imaging modalities. Financial sponsorship and integration of academia, industry, and government efforts will be important factors in translating the technology for clinical research in oncology. This white paper is intended to provide recommendations with this goal in mind