Earth is home to a remarkable diversity of plant forms and life histories, yet comparatively few essential trait combinations have proved evolutionarily viable in today's terrestrial biosphere. By ...analysing worldwide variation in six major traits critical to growth, survival and reproduction within the largest sample of vascular plant species ever compiled, we found that occupancy of six-dimensional trait space is strongly concentrated, indicating coordination and trade-offs. Three-quarters of trait variation is captured in a two-dimensional global spectrum of plant form and function. One major dimension within this plane reflects the size of whole plants and their parts; the other represents the leaf economics spectrum, which balances leaf construction costs against growth potential. The global plant trait spectrum provides a backdrop for elucidating constraints on evolution, for functionally qualifying species and ecosystems, and for improving models that predict future vegetation based on continuous variation in plant form and function.
Forte des travaux pionniers de ses figures historiques emblématiques comme Pierre et Marie Curie, Claudius Regaud ou Antoine Lacassagne, la radiobiologie française se trouve aujourd’hui dans une ...situation dramatique en matière de ressources humaines et d’expertise, comme la plupart des pays développés. Pourtant, les progrès considérables dans la thérapie des cancers et dans le radiodiagnostic, les enjeux de Défense Nationale et de l’exploration spatiale ainsi qu’une attente sociétale grandissante pour une évaluation objective des risques liés aux radiations ionisantes devrait encourager nos institutions à maintenir et préserver le savoir et le savoir-faire des radiobiologistes. Sans proposer un catalogue des thèmes et des laboratoires, l’objectif de cet article, est de mieux analyser et comprendre l’évolution historique et scientifique de la radiobiologie française pour mieux en dégager les enjeux de demain.
Despite of the pioneering works of its emblematic historical figures such as Pierre and Marie Curie, Claudius Regaud and Antoine Lacassagne, French radiobiology today finds itself in a dramatic situation in terms of human resources and expertise, like most developed countries. However, the considerable advances in cancer therapy and in radiodiagnosis, the issues of National Defense and space exploration as well as a growing societal expectation for an objective assessment of the risks linked to ionizing radiation should encourage the French institutions to maintain and preserve the knowledge and know-how of radiobiologists. Without offering a catalog of themes and laboratories, the objective of this article is to better analyze and understand the historical and scientific evolution of French radiobiology in order to better identify the challenges of tomorrow.
•FLASH radiation dose-rates consume all the local tissue O2 to form reactive organic hydroperoxides.•Fenton type reactions will be limited in normal vs. cancer tissues due to lower levels of labile ...Fe.•Normal tissues are expected to remove organic hydroperoxides more effectively relative to tumor tissues.•Since tumor tissue cannot remove hydroperoxides as effectively, FLASH and conventional dose rate irradiation are more isoefficient at killing tumor cells compared to normal cells.
For decades the field of radiation oncology has sought to improve the therapeutic ratio through innovations in physics, chemistry, and biology. To date, technological advancements in image guided beam delivery techniques have provided clinicians with their best options for improving this critical tool in cancer care. Medical physics has focused on the preferential targeting of tumors while minimizing the collateral dose to the surrounding normal tissues, yielding only incremental progress. However, recent developments involving ultra-high dose rate irradiation termed FLASH radiotherapy (FLASH-RT), that were initiated nearly 50 years ago, have stimulated a renaissance in the field of radiotherapy, long awaiting a breakthrough modality able to enhance therapeutic responses and limit normal tissue injury. Compared to conventional dose rates used clinically (0.1–0.2 Gy/s), FLASH can implement dose rates of electrons or X-rays in excess of 100 Gy/s. The implications of this ultra-fast delivery of dose are significant and need to be re-evaluated to appreciate the fundamental aspects underlying this seemingly unique radiobiology. The capability of FLASH to significantly spare normal tissue complications in multiple animal models, when compared to conventional rates of dose-delivery, while maintaining persistent growth inhibition of select tumor models has generated considerable excitement, as well as skepticism. Based on fundamental principles of radiation physics, radio-chemistry, and tumor vs. normal cell redox metabolism, this article presents a series of testable, biologically relevant hypotheses, which may help rationalize the differential effects of FLASH irradiation observed between normal tissue and tumors.
Bioinformatics has become increasingly integral to radiation biology, also known as radiobiology, providing substantial support through data storage, conversion, visualization, and sharing. This ...review aims to deepen understanding of bioinformatics application in radiobiology by introducing key databases and analytical tools in radiobiology, including general bioinformatics databases, radiobiology-specific databases, data processing tools, and statistical analysis tools for differentially expressed genes (DEGs) and LC/MS analysis. This review also discusses bioinformatics applications in radiobiological fields, such as radioresistance and immune cell enrichment. Despite these advances, challenges such as data interoperability remain. Methods and projects to address these issues, such as GeCo and GMQL, are also examined.
Radiation on Earth or in Space: What Does It Change? Restier-Verlet, Juliette; El-Nachef, Laura; Ferlazzo, Mélanie L ...
International journal of molecular sciences,
04/2021, Letnik:
22, Številka:
7
Journal Article
Recenzirano
Odprti dostop
After having been an instrument of the Cold War, space exploration has become a major technological, scientific and societal challenge for a number of countries. With new projects to return to the ...Moon and go to Mars, radiobiologists have been called upon to better assess the risks linked to exposure to radiation emitted from space (IRS), one of the major hazards for astronauts. To this aim, a major task is to identify the specificities of the different sources of IRS that concern astronauts. By considering the probabilities of the impact of IRS against spacecraft shielding, three conclusions can be drawn: (1) The impacts of heavy ions are rare and their contribution to radiation dose may be low during low Earth orbit; (2) secondary particles, including neutrons emitted at low energy from the spacecraft shielding, may be common in deep space and may preferentially target surface tissues such as the eyes and skin; (3) a "bath of radiation" composed of residual rays and fast neutrons inside the spacecraft may present a concern for deep tissues such as bones and the cardiovascular system. Hence, skin melanoma, cataracts, loss of bone mass, and aging of the cardiovascular system are possible, dependent on the dose, dose-rate, and individual factors. This suggests that both radiosusceptibility and radiodegeneration may be concerns related to space exploration. In addition, in the particular case of extreme solar events, radiosensitivity reactions-such as those observed in acute radiation syndrome-may occur and affect blood composition, gastrointestinal and neurologic systems. This review summarizes the specificities of space radiobiology and opens the debate as regards refinements of current radiation protection concepts that will be useful for the better estimation of risks.
•Bottom-up radiation chemistry study reproduced observed radiolytic oxygen depletion (ROD) with high accuracy.•Dynamical nature of oxygen depletion and its impact on OER taken into account for the ...first time.•Negligible impact of ROD on radiosensitivity through transient hypoxia in conditions of reported experiments.•ROD impact on therapeutic window occurs eventually in opposite direction.
Recent observations in animal models show that ultra-high dose rate (“FLASH”) radiation treatment significantly reduces normal tissue toxicity maintaining an equivalent tumor control. The dependence of this “FLASH” effect on target oxygenation has led to the assumption that oxygen “depletion” could be its major driving force.
In a bottom-up approach starting from the chemical track evolution of 1 MeV electrons in oxygenated water simulated with the TRAX-CHEM Monte Carlo code, we determine the oxygen consumption and radiolytic reactive oxygen species production following a short radiation pulse. Based on these values, the effective dose weighted by oxygen enhancement ratio (OER) or the in vitro cell survival under dynamic oxygen pressure is calculated and compared to that of conventional exposures, at constant OER.
We find an excellent agreement of our Monte Carlo predictions with the experimental value for radiolytic oxygen removal from oxygenated water. However, the application of the present model to published radiobiological experiment conditions shows that oxygen depletion can only have a negligible impact on radiosensitivity through oxygen enhancement, especially at typical experimental oxygenations where a FLASH effect has been observed.
We show that the magnitude and dependence of the “oxygen depletion” hypothesis are not consistent with the observed biological effects of FLASH irradiation. While oxygenation plays an undoubted role in mediating the FLASH effect, we conclude that state-of-the-art radiation chemistry models do not support oxygen depletion and radiation-induced transient hypoxia as the main mechanism.
As part of the special issue on 'Women in Science', this review offers a perspective on past and ongoing work in the field of normal (non-cancer) tissue radiation biology, highlighting the work of ...many of the leading contributors to this field of research. We discuss some of the hypotheses that have guided investigations, with a focus on some of the critical organs considered dose-limiting with respect to radiation therapy, and speculate on where the field needs to go in the future.
The scope of work that makes up normal tissue radiation biology has and continues to play a pivotal role in the radiation sciences, ensuring the most effective application of radiation in imaging and therapy, as well as contributing to radiation protection efforts. However, despite the proven historical value of preclinical findings, recent decades have seen clinical practice move ahead with altered fractionation scheduling based on empirical observations, with little to no (or even negative) supporting scientific data. Given our current appreciation of the complexity of normal tissue radiation responses and their temporal variability, with tissue- and/or organ-specific mechanisms that include intra-, inter- and extracellular messaging, as well as contributions from systemic compartments, such as the immune system, the need to maintain a positive therapeutic ratio has never been more urgent. Importantly, mitigation and treatment strategies, whether for the clinic, emergency use following accidental or deliberate releases, or reducing occupational risk, will likely require multi-targeted approaches that involve both local and systemic intervention. From our personal perspective as five 'Women in Science', we would like to acknowledge and applaud the role that many female scientists have played in this field. We stand on the shoulders of those who have gone before, some of whom are fellow contributors to this special issue.
Proton radiobiology Tommasino, Francesco; Durante, Marco
Cancers,
02/2015, Letnik:
7, Številka:
1
Journal Article, Book Review
Recenzirano
Odprti dostop
In addition to the physical advantages (Bragg peak), the use of charged particles in cancer therapy can be associated with distinct biological effects compared to X-rays. While heavy ions (densely ...ionizing radiation) are known to have an energy- and charge-dependent increased Relative Biological Effectiveness (RBE), protons should not be very different from sparsely ionizing photons. A slightly increased biological effectiveness is taken into account in proton treatment planning by assuming a fixed RBE of 1.1 for the whole radiation field. However, data emerging from recent studies suggest that, for several end points of clinical relevance, the biological response is differentially modulated by protons compared to photons. In parallel, research in the field of medical physics highlighted how variations in RBE that are currently neglected might actually result in deposition of significant doses in healthy organs. This seems to be relevant in particular for normal tissues in the entrance region and for organs at risk close behind the tumor. All these aspects will be considered and discussed in this review, highlighting how a re-discussion of the role of a variable RBE in proton therapy might be well-timed.
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