China 
Africa 
Explore chapters and articles related to this topic
The essence of R in head and neck cancer
Published in Ruijiang Li, Lei Xing, Sandy Napel, Daniel L. Rubin, Radiomics and Radiogenomics, 2019
Hesham Elhalawani, Arvind Rao, Clifton D. Fuller
With the advent of immunotherapy in head and neck cancers management, programmed death-ligand 1 (PD-L1) upregulation has been identified as a potential mechanism by which cancer cells evade human immune system, and hence a potential therapeutic target (Thompson et al. 2004). Radiomics has exhibited preliminary potential for linking 18F-FDG-PET textural features to PD-L1 expression, detected through immunohistochemistry (IHC) in a follow-up study by the same group on a cohort of 53 OPC patients. PD-L1 expression intensity was inversely associated with gray-level non-uniformity for run, run percentage, and short-zone low gray-level emphasis (SZLGE; p = 0.04, γ = −0.28). More specifically, some texture features could predict a PD-L1 expression intensity ≥5% with a similar pattern noticed when PD-L1 expression was dichotomized at 1%. Interestingly, on setting a cut-off of 0.26% for GLCM (one of the negative predictors of PD-L1 expression), its accuracy for predicting expression levels <5% almost tripled. Naturally, interpretation of this study results would be restricted by the small cohort size given the much bigger number of tested features. However, this was the first study to test the ability of quantitative metabolic imaging phenotypes to predict tumor PD-L1 expression, as well as other protein biomarkers of tumor microenvironment elements including hypoxia, angiogenesis, radioresistance, and tumor proliferation (Chen et al. 2018). In addition, this study paves the way for developing textural features that can predict or assess the therapeutic effects of PD-1 or PD-L1 antibodies, i.e., immune checkpoint inhibitors.
Why Human Enhancement is Necessary for Successful Human Deep-space Missions
Published in The New Bioethics, 2019
Konrad Szocik, Martin Braddock
One important scientific issue is the difference between short high exposures and long low exposures to radiation, which apply to space missions within and beyond the protective effects of the Van Allen belts outside of the solar system. The low dose may well have less impact as the human body has some ability to repair radiation damage. It is likely that short high doses will carry a greater level of risk and it is essential that astronauts shelter or are protected from events which generate short high doses such as solar particle events (SPE) (Hu 2017). Long, low exposures might be mitigated against if DNA repair mechanisms can be enhanced and the NASA roadmap for conferring radioresistance proposes some strategies, based in part upon identification of radioresistance factors from extremophiles (Cortese et al. 2018). The assessments ESA made 10–15 years ago noted that without a major advance in radiation protection (e.g. much better shielding, reduced travel time) astronauts may survive a mission to Mars and back to Earth but cannot go further into the solar system or beyond it. Space missions also cause a substantial loss of bone mineral density and the deleterious impact of microgravity may be augmented by space radiation (Vico and Hargens 2018), and vice versa (Moreno-Villanueva et al. 2017).
The role of BMP-2, low-level laser therapy and low x-ray doses in dental follicle stem cell migration
Published in Particulate Science and Technology, 2018
Ondine Lucaciu, Bogdan Crisan, Mihaela Hedesiu, Olga Soritau, Noemi Dirzu, Liana Crisan, Radu Campian, Grigore Baciut, Mihaela Baciut, Florin Onisor, Cristian Dinu, Simion Bran
No statistically significant differences between the groups were obtained. The only statistically significant differences are in favor for the group with BMP-2 growth factor compared to the control one in the case of nonirradiated group (Table 1). This result is in line with the idea that stem cells are radioresistant. A rational conclusion is that performing CBCT after bone reconstruction or implant placement will not decrease the migration potential of DFSCs and by that will not influence the dental implant osseointegration process or the bone reconstruction process. In a previous study, Tomuleasa et al. (2010) showed that ionizing radiation stimulated stem cell proliferation and differentiation at 0.5 Gy and 1 Gy. The radioresistance of MSCs with maintaining their stem cell characteristics even after high radiation doses was reported in several studies. Some mechanisms were investigated such as efficient DNA damage recognition, double-strand break repair, and evasion of apoptosis by Nicolay et al. (2015). Although irradiated MSCs at low doses induced reduction of cell cycling with triggering of senescence and noncycling cells showed some unrepaired damages, upon the whole, MSCs properly activated the DNA repair signaling (Alessio et al. 2015).