This work is an overview of the literature in the area of microwave treatment of starch strongly related to changes in its physicochemical, functional and structural properties. The importance of ...good knowledge of the microwave parameters and starch dielectric properties is highlighted to avoid the improper microwave application on starch or starch‐based materials. Future perspectives of microwave processing of starch are suggested.
Radiation hormesis in plants Volkova, Polina Yu; Bondarenko, Ekaterina V.; Kazakova, Elizaveta A.
Current opinion in toxicology,
June 2022, 2022-06-00, Letnik:
30
Journal Article
Recenzirano
In plants, radiation hormesis phenomenon occurs as enhanced growth, accelerated development, increased tolerance to stressors, or accumulation of compounds of interest in response to low-dose ...irradiation. This review summarizes the recent findings regarding radiation hormesis in plants in response to ionising or UV-radiation. While molecular mechanisms of UV-hormesis are clearer and involve sensing of UV-radiation by the specific photoreceptors, the precise molecular events underlying hormetic responses to ionising radiation are yet to be uncovered. Based on the available information, the scheme of possible pathways triggering radiation stimulation response in cells is discussed. It is argued that beneficial responses to low-dose ionising radiation may depend on the optimization of hydrogen peroxide (H2O2) levels and the interplay between the signalling pathways of reactive oxygen species (ROS) and phytohormones.
The cyclic GMP–AMP synthase–stimulator of interferon genes (cGAS–STING) pathway is an essential component of the innate immune system and is central to the identification of abnormal DNA leakage ...caused by ionising radiation (IR) damage. Cell‐intrinsic cGAS–STING initiation has been revealed to have tremendous potential for facilitating interferon synthesis and T‐cell priming. Targeting the cGAS–STING axis has been proposed as a strategy to improve radiosensitivity or enhance immunosurveillance. However, due to the complex biology of the irradiated tumour microenvironment and the extensive involvement of the cGAS–STING pathway in various physiological and pathological processes, many defects in this strategy limit the therapeutic effect. Here, we outline the molecular mechanisms by which IR activates the cGAS–STING pathway and analyse the dichotomous roles of the cGAS–STING pathway in modulating cancer immunity after radiotherapy (RT). Then, based on the crosstalk between the cGAS–STING pathway and other signalling events induced by IR, such as necroptosis, autophagy and other cellular effects, we discuss the immunomodulatory actions of the broad cGAS–STING signalling network in RT and their potential therapeutic applications. Finally, recent advances in combination therapeutic strategies targeting cGAS–STING in RT are explored.
Ionising radiation (IR)‐induced activation of the cGAS–STING cytosolic nucleic acid sensing pathway has a dichotomous role in initiating cancer immunosurveillance and immunosuppression, which is critical for remodelling the tumour microenvironment. Other signalling events activated after IR, such as various cell death modalities, can further regulate cancer immunity indirectly by enhancing or inhibiting cGAS–STING signalling. Therefore, targeting the cGAS–STING pathway in radiotherapy (RT) to enhance antitumour immune activation without causing negative effects such as immunosuppression and RT resistance is a promising combination therapy approach.
Purpose:
This work provides an interpretation of the chromatic properties of GafChromic™EBT3 films based on the chemical nature of the polydiacetylene (PDA) molecules formed upon interaction with ...ionizing radiation. The EBT3 films become optically less transparent with increasing radiation dose as a result of the radiation-induced polymerization of diacetylene monomers. In contrast to empirical quantification of the chromatic properties, less attention has been given to the underlying molecular mechanism that induces the strong decrease in transparency.
Methods:
Unlaminated GafChromic™EBT3 films were irradiated with a 6 MV photon beam to dose levels up to 20 Gy. The optical absorption properties of the films were investigated using visible (vis) spectroscopy. The presence of PDA molecules in the active layer of the EBT3 films was investigated using Raman spectroscopy, which probes the vibrational modes of the molecules in the layer. The vibrational modes assigned to PDA’s were used in a theoretical vis-absorption model to fit our experimental vis-absorption spectra. From the fit parameters, one can assess the relative contribution of different PDA conformations and the length distribution of PDA’s in the film.
Results:
Vis-spectroscopy shows that the optical density increases with dose in the full region of the visible spectrum. The Raman spectrum is dominated by two vibrational modes, most notably by the ν(C≡C) and the ν(C=C) stretching modes of the PDA backbone. By fitting the vis-absorption model to experimental spectra, it is found that the active layer contains two distinct PDA conformations with different absorption properties and reaction kinetics. Furthermore, the mean PDA conjugation length is found to be 2–3 orders of magnitude smaller than the crystals PDA’s are embedded in.
Conclusions:
Vis- and Raman spectroscopy provided more insight into the molecular nature of the radiochromic properties of EBT3 films through the identification of the excited states of PDA and the presence of two PDA conformations. The improved knowledge on the molecular composition of EBT3’s active layer provides a framework for future fundamental modeling of the dose–response.
Radiotherapy (ionising radiation; IR) is utilised in the treatment of ~50% of all human cancers, and where the therapeutic effect is largely achieved through DNA damage induction. In particular, ...complex DNA damage (CDD) containing two or more lesions within one to two helical turns of the DNA is a signature of IR and contributes significantly to the cell killing effects due to the difficult nature of its repair by the cellular DNA repair machinery. The levels and complexity of CDD increase with increasing ionisation density (linear energy transfer, LET) of the IR, such that photon (X-ray) radiotherapy is deemed low-LET whereas some particle ions (such as carbon ions) are high-LET radiotherapy. Despite this knowledge, there are challenges in the detection and quantitative measurement of IR-induced CDD in cells and tissues. Furthermore, there are biological uncertainties with the specific DNA repair proteins and pathways, including components of DNA single and double strand break mechanisms, that are engaged in CDD repair, which very much depends on the radiation type and associated LET. However, there are promising signs that advancements are being made in these areas and which will enhance our understanding of the cellular response to CDD induced by IR. There is also evidence that targeting CDD repair, particularly through inhibitors against selected DNA repair enzymes, can exacerbate the impact of higher LET, which could be explored further in a translational context.
Abstract DNA damage of exposed tumour tissue leading to cell death is one of the detrimental effects of ionising radiation that is exploited, with beneficial consequences, for radiotherapy. The ...pattern of the discrete energy depositions during passage of the ionising track of radiation defines the spatial distribution of lesions induced in DNA with a fraction of the DNA damage sites containing clusters of lesions, formed over a few nanometres, against a background of endogenously induced individual lesions. These clustered DNA damage sites, which may be considered as a signature of ionising radiation, underlie the deleterious biological consequences of ionising radiation. The concepts developed rely in part on the fact that ionising radiation creates significant levels of clustered DNA damage, including complex double-strand breaks (DSB), to kill tumour cells as clustered damage sites are difficult to repair. This reduced repairability of clustered DNA damage using specific repair pathways is exploitable in radiotherapy for the treatment of cancer. We discuss some potential strategies to enhance radiosensitivity by targeting the repair pathways of radiation-induced clustered damage and complex DNA DSB, through inhibition of specific proteins that are not required in the repair pathways for endogenous damage. The variety and severity of DNA damage from ionising radiation is also influenced by the tumour microenvironment, being especially sensitive to the oxygen status of the cells. For instance, nitric oxide is known to influence the types of damage induced by radiation under hypoxic conditions. A potential strategy based on bioreductive activation of pro-drugs to release nitric oxide is discussed as an approach to deliver nitric oxide to hypoxic tumours during radiotherapy. The ultimate aim of this review is to stimulate thinking on how knowledge of the complexity of radiation-induced DNA damage may contribute to the development of adjuncts to radiotherapy.
Understanding the effects of ionizing radiation (IR) on plants is important for environmental protection, for agriculture and horticulture, and for space science but plants have significant ...biological differences to the animals from which much relevant knowledge is derived. The effects of IR on plants are understood best at acute high doses because there have been; (a) controlled experiments in the field using point sources, (b) field studies in the immediate aftermath of nuclear accidents, and (c) controlled laboratory experiments. A compilation of studies of the effects of IR on plants reveals that although there are numerous field studies of the effects of chronic low doses on plants, there are few controlled experiments that used chronic low doses. Using the Bradford-Hill criteria widely used in epidemiological studies we suggest that a new phase of chronic low-level radiation research on plants is desirable if its effects are to be properly elucidated. We emphasize the plant biological contexts that should direct such research. We review previously reported effects from the molecular to community level and, using a plant stress biology context, discuss a variety of acute high- and chronic low-dose data against Derived Consideration Reference Levels (DCRLs) used for environmental protection. We suggest that chronic low-level IR can sometimes have effects at the molecular and cytogenetic level at DCRL dose rates (and perhaps below) but that there are unlikely to be environmentally significant effects at higher levels of biological organization. We conclude that, although current data meets only some of the Bradford-Hill criteria, current DCRLs for plants are very likely to be appropriate at biological scales relevant to environmental protection (and for which they were intended) but that research designed with an appropriate biological context and with more of the Bradford-Hill criteria in mind would strengthen this assertion. We note that the effects of IR have been investigated on only a small proportion of plant species and that research with a wider range of species might improve not only the understanding of the biological effects of radiation but also that of the response of plants to environmental stress.
In recent years, there has been an increased awareness and understanding of the varying gender identities within our society. Consequently, there has also been a need for healthcare providers to be ...cognizant of the unique needs of a gender-diverse population. Determining the pregnancy status of transgender, gender-diverse and non-binary patients in medical imaging settings has been poorly handled, and there is a lack of standardisation in the Australian and Aotearoa New Zealand setting. The potential risk of exposing a gender-diverse pregnant patient to ionising radiation increases the need for guidance to ensure potentially pregnant persons are not missed during screening questionnaires. This review article explores various approaches to pregnancy status determination for gender-diverse patients, recognising the complexities involved and emphasising the need for future work to establish a widely accepted solution.
Liquid crystals (LCs) can be promising for detection of ionising radiation (IR). However, there is little information about their interaction with IR and there are no systemic studies of the ...dosimetric application of LCs. In this communication, we show for the first time the capabilities of a new type of radiation detector - cholesteric liquid-crystalline dispersion (CLCD) of DNA obtained using polyethylene glycol (PEG) and salt indued condensation. Irradiation of the DNA CLCD samples with 0-100 kGy of 7.6 MeV bremsstrahlung led to significant change in their circular dichroism (CD): ≈5% and ≈12% increase in the signal was observed at 10 and 20 kGy, while in the range of 20-90 kGy the CD signal decreased linearly. Thus, detectors based on DNA CLCD could be of interest for such application of IR as material modification or radiation sterilisation. At the same time irradiation can help to stabilise dispersion particles and can be used to prevent their sedimentation. Unirradiated samples degraded within 24 h after preparation, while the irradiated ones were able to maintain the intensity of CD signal for more than 168 h.Schematic representation of the dual effect of radiation exposure the DNA CLCD.
The end of the 19th and the beginning of the 20th century marked a period of fundamental discoveries in the physics of ionising radiation (X radiation and radioactivity). Isolating radium, a highly ...radioactive element, immediately opened the way to its application for medical therapeutic purposes. It turned out that the sources of ionising radiation are very effective for changes localised on the skin and at small depths under the skin but not for lesions at greater depths. Interestingly, the inventor of the modern telephone, Alexander Graham Bell, was the first to come up with the idea of placing radium sources in glass tubes and placing them directly in the pathologically changed tissues of the patients to be treated (at greater depths). That period marked the beginning of a highly successful era in radium therapy, involving the use of capsules and needles filled with radium, which eventually led to the development of modern brachytherapy. Unfortunately, for several decades people believed in the universally therapeutic properties of radium, so that (fortunately in smaller quantities) it was added to water, food, hygiene products, etc.
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