Some ideas about electrochemical characterization of dental alloys

Extensions and modifications of standard electrochemical techniques, accounting for unique conditions related to biological considerations, have proved useful in attacking some problems related to biocompatibility of the Biomaterial. Some authors have demonstrated that modern electrochemical techniques can be used to clarify some difficult problems in the field of biomaterials. Precious alloys can not be apply for all cases especially such as long range bridges or prostheses. For this reason, Ni-Cr as well as Co-Cr casting alloys have been used for dental application as alternatives to precious alloys. The biocompatibility of Ni-Cr alloys have been questioned because of their corrosive, allergenic, and even mutagenic potentials. The nature of passive films on metals and alloys is the ultimate factor which controls their corrosion behavior. There is little reliable information on the effects of the physical and chemical factors involved in the tissue response to an implant and the associated ionic release on the cellmaterial interaction. Depending of the casting process during the production of a dental prosthesis, these alloys may show different phases, ones may be more stable than other. For this reason, the development of a quick and simple method for determining the corrosion behavior as a control test in the production Biomecánica, 9 (1), 2001, pp. 66-70 67 of a dental prosthesis is of great interest. The purpose of this work was to show some results on the corrosion behavior of two different commercial alloys: Wiron 99 ( Ni-Cr alloy) and Aurolloyd kf (Au alloy). These results were obtained by several electrochemical methods: Open Circuit Potential vs time and Liner Sweep Voltammetry for Wiron 99, and Open Circuit Potential vs time and Cyclic Voltammetry for Aurolloyd kf. In the case of the Ni-Cr alloys, it is concluded that with the combination of both methods, it is possible to know how the corrosion behavior of casting individual dental Ni-Cr alloy prosthesis is, and in the case of Au alloy, it is concluded that the differences in electrochemical behavior strongly depend of surface oxides formed. These results showed that one of the studied combination, Eoc-Rp or Eoc-CV characterization, could be selected as control test after casting of individual prosthesis.Peer Reviewe

An integrated MR/PET system: prospective applications

Radiology is strongly depending on medical imaging technology and consequently directing technological progress. A novel technology can only be established, however, if improved diagnostic accuracy influence on therapeutic management and/or overall reduced cost can be evidenced. It has been demonstrated recently that Magnetic Resonance Imaging (MRI) and Positron Emission Tomography (PET) can technologically be integrated into one single hybrid system. Some scientific arguments on the benefits are obvious, e.g., that simultaneous imaging of morphological and functional information will improve tissue characterization. However, crossfire of questions still remains: What unmet radiological needs are addressed by the novel system? What level of hardware integration is reasonable, or would software-based image co-registration be sufficient? Will MR/PET achieve higher diagnostic accuracy compared to separate imaging? What is the added value compared to other hybrid imaging modalities like PET/CT? And finally, is the system economically reasonable and has the potential to reduce overall costs for therapy planning and monitoring? This article tries to highlight some perspectives of applying an integrated MR/PET system for simultaneous morphologic and functional imaging

Catching Element Formation In The Act

Gamma-ray astronomy explores the most energetic photons in nature to address some of the most pressing puzzles in contemporary astrophysics. It encompasses a wide range of objects and phenomena: stars, supernovae, novae, neutron stars, stellar-mass black holes, nucleosynthesis, the interstellar medium, cosmic rays and relativistic-particle acceleration, and the evolution of galaxies. MeV gamma-rays provide a unique probe of nuclear processes in astronomy, directly measuring radioactive decay, nuclear de-excitation, and positron annihilation. The substantial information carried by gamma-ray photons allows us to see deeper into these objects, the bulk of the power is often emitted at gamma-ray energies, and radioactivity provides a natural physical clock that adds unique information. New science will be driven by time-domain population studies at gamma-ray energies. This science is enabled by next-generation gamma-ray instruments with one to two orders of magnitude better sensitivity, larger sky coverage, and faster cadence than all previous gamma-ray instruments. This transformative capability permits: (a) the accurate identification of the gamma-ray emitting objects and correlations with observations taken at other wavelengths and with other messengers; (b) construction of new gamma-ray maps of the Milky Way and other nearby galaxies where extended regions are distinguished from point sources; and (c) considerable serendipitous science of scarce events -- nearby neutron star mergers, for example. Advances in technology push the performance of new gamma-ray instruments to address a wide set of astrophysical questions.Comment: 14 pages including 3 figure

Expression of Transketolase like gene 1 (TKTL1) predicts disease-free survival in patients with locally advanced rectal cancer receiving neoadjuvant chemoradiotherapy

<p>Abstract</p> <p>Background</p> <p>For patients with locally advanced rectal cancer (LARC) neoadjuvant chemoradiotherapy is recommended as standard therapy. So far, no predictive or prognostic molecular factors for patients undergoing multimodal treatment are established. Increased angiogenesis and altered tumour metabolism as adaption to hypoxic conditions in cancers play an important role in tumour progression and metastasis. Enhanced expression of Vascular-endothelial-growth-factor-receptor <it>(VEGF-R</it>) and Transketolase-like-1 (<it>TKTL1</it>) are related to hypoxic conditions in tumours. In search for potential prognostic molecular markers we investigated the expression of <it>VEGFR-1</it>, <it>VEGFR-2 </it>and <it>TKTL1 </it>in patients with LARC treated with neoadjuvant chemoradiotherapy and cetuximab.</p> <p>Methods</p> <p>Tumour and corresponding normal tissue from pre-therapeutic biopsies of 33 patients (m: 23, f: 10; median age: 61 years) with LARC treated in phase-I and II trials with neoadjuvant chemoradiotherapy (cetuximab, irinotecan, capecitabine in combination with radiotherapy) were analysed by quantitative PCR.</p> <p>Results</p> <p>Significantly higher expression of <it>VEGFR-1/2 </it>was found in tumour tissue in pre-treatment biopsies as well as in resected specimen after neoadjuvant chemoradiotherapy compared to corresponding normal tissue. High <it>TKTL1 </it>expression significantly correlated with disease free survival. None of the markers had influence on early response parameters such as tumour regression grading. There was no correlation of gene expression between the investigated markers.</p> <p>Conclusion</p> <p>High <it>TKTL-1 </it>expression correlates with poor prognosis in terms of 3 year disease-free survival in patients with LARC treated with intensified neoadjuvant chemoradiotherapy and may therefore serve as a molecular prognostic marker which should be further evaluated in randomised clinical trials.</p

A Decade of Incorporating Social Sciences in the Integrated Marine Biosphere Research Project (IMBeR): Much Done, Much to Do?

Successful management and mitigation of marine challenges depends on cooperation and knowledge sharing which often occurs across culturally diverse geographic regions. Global ocean science collaboration is therefore essential for developing global solutions. Building effective global research networks that can enable collaboration also need to ensure inter- and transdisciplinary research approaches to tackle complex marine socio-ecological challenges. To understand the contribution of interdisciplinary global research networks to solving these complex challenges, we use the Integrated Marine Biosphere Research (IMBeR) project as a case study. We investigated the diversity and characteristics of 1,827 scientists from 11 global regions who were attendees at different IMBeR global science engagement opportunities since 2009. We also determined the role of social science engagement in natural science based regional programmes (using key informants) and identified the potential for enhanced collaboration in the future. Event attendees were predominantly from western Europe, North America, and East Asia. But overall, in the global network, there was growing participation by females, students and early career researchers, and social scientists, thus assisting in moving toward interdisciplinarity in IMBeR research. The mainly natural science oriented regional programmes showed mixed success in engaging and collaborating with social scientists. This was mostly attributed to the largely natural science (i.e., biological, physical) goals and agendas of the programmes, and the lack of institutional support and push to initiate connections with social science. Recognising that social science research may not be relevant to all the aims and activities of all regional programmes, all researchers however, recognised the (potential) benefits of interdisciplinarity, which included broadening scientists’ understanding and perspectives, developing connections and interlinkages, and making science more useful. Pathways to achieve progress in regional programmes fell into four groups: specific funding, events to come together, within-programme-reflections, and social science champions. Future research programmes should have a strategic plan to be truly interdisciplinary, engaging natural and social sciences, as well as aiding early career professionals to actively engage in such programmes.This publication resulted in part from support from the U.S. National Science Foundation (Grant OCE-1840868) to the Scientific Committee on Oceanic Research (SCOR)

Technically advanced and SF6-free 145 kV blue GIS

SF6, the most commonly used arc extinguishing and insulating gas in gas-insulated switchgears (GIS), is a greenhouse gas with high global warming potential, requiring careful handling throughout its life cycle. In order to reduce the GIS-related global warming impact, innovative solutions using alternative gases have been developed by different manufacturers, especially the blue GIS from Siemens – available for 145 kV / 40 kA / 3150 A – with clean air insulation and vacuum switching technology shows many technical advantages

Liebig y la Farmacia (en francés)

Justus von Liebig (1803&ntilde;1873) n&Egrave; le 12 mai 1803 compte parmi les plus grands chimistes allemands. &nbsp;́ P&Euml;re de la chimie organique a, pionnier de la chimie agricole et cr&Egrave;ateur de &nbsp;́ l&iacute;extrait de viande a l&Egrave;gen- daire, il devint particuli&Euml;rement c&Egrave;l&Euml;bre. Une c&Egrave;l&Egrave;brit&Egrave; qui se refl&Euml;te dans la multitude d&iacute;&Egrave;crits consacr&Egrave;s &Dagger; sa vie et son travail. &iquest; part les biogra- phies d&Egrave;taill&Egrave;es (1-3), il existe &Egrave;galement plusieurs recueils de lettres (4- 6). Il parait donc &Egrave;tonnant que Liebig qui par moments travaillait dans une pharmacie, &Egrave;tait consid&Egrave;r&Egrave; si peu dans l&iacute;historiographie de la pharmacie (7). Ce texte regarde de plus pr&Euml;s sa relation avec la pharmacie.Justus von Liebig (1803&ntilde;1873) n&Egrave; le 12 mai 1803 compte parmi les plus grands chimistes allemands. &nbsp;́ P&Euml;re de la chimie organique a, pionnier de la chimie agricole et cr&Egrave;ateur de &nbsp;́ l&iacute;extrait de viande a l&Egrave;gen- daire, il devint particuli&Euml;rement c&Egrave;l&Euml;bre. Une c&Egrave;l&Egrave;brit&Egrave; qui se refl&Euml;te dans la multitude d&iacute;&Egrave;crits consacr&Egrave;s &Dagger; sa vie et son travail. &iquest; part les biogra- phies d&Egrave;taill&Egrave;es (1-3), il existe &Egrave;galement plusieurs recueils de lettres (4- 6). Il parait donc &Egrave;tonnant que Liebig qui par moments travaillait dans une pharmacie, &Egrave;tait consid&Egrave;r&Egrave; si peu dans l&iacute;historiographie de la pharmacie (7). Ce texte regarde de plus pr&Euml;s sa relation avec la pharmacie

HLA-E/human beta2-microglobulin transgenic pigs: protection against xenogeneic human anti-pig natural killer cell cytotoxicity

BACKGROUND: Natural killer (NK) cells participate in pig-to-primate xenograft rejection both by antibody-dependent and -independent mechanisms. A majority of human NK cells express the inhibitory receptor CD94/NKG2A, which binds specifically to human leukocyte antigen (HLA)-E, a trimeric complex consisting of the HLA-E heavy chain, beta2-microglobulin (beta2m), and a peptide derived from the leader sequence of some major histocompatibility complex class I molecules. METHODS: To use this mechanism for protection of pig tissues against human NK cell-mediated cytotoxicity, we generated transgenic pigs by pronuclear microinjection of genomic fragments of HLA-E with an HLA-B7 signal sequence and of human beta2-microglobulin (hubeta2m) into zygotes. RESULTS: Three transgenic founder pigs were generated. Northern blot analysis of RNA from peripheral blood mononuclear cells revealed the presence of the expected transcript sizes for both transgenes in two of the three founders. The founder with the highest expression and his offspring were characterized in detail. Fluorescence-activated cell sorting (FACS) and Western blot analyses demonstrated consistent expression of HLA-E and hubeta2m in peripheral blood mononuclear cells. Immunohistochemistry revealed the presence of HLA-E and hubeta2m on endothelial cells of many organs, including heart and kidney. In vitro studies showed that lymphoblasts and endothelial cells derived from HLA-E/hubeta2m transgenic pigs are effectively protected against human NK cell-mediated cytotoxicity, depending on the level of CD94/NKG2A expression on the NK cells. Further, HLA-E/hubeta2m expression on porcine endothelial cells inhibited the secretion of interferon (IFN)-gamma by co-cultured human NK cells. CONCLUSIONS: This novel approach against cell-mediated xenogeneic responses has important implications for the generation of multitransgenic pigs as organ donors for clinical xenotransplantation