Radical yields in DNA exposed to ionizing radiation: Role of energy and charge transfer

1990 ◽  
Vol 68 (9) ◽  
pp. 962-966 ◽  
Author(s):  
John H. Miller ◽  
Charles E. Swenberg
Keyword(s):  
Charge Transfer ◽  
Ionizing Radiation ◽  
Mechanistic Model ◽  
Experimental Studies ◽  
High Mobility ◽  
Orientation Dependence ◽  
Model Calculations ◽  
Insight Into ◽  
High Linear Energy Transfer

Theoretical and experimental studies of free-radical yields in oriented DNA samples exposed to ionizing radiation with high linear energy transfer at 77 K are discussed. The dependence of radical yields on the orientation of DNA chains relative to the particle flux is being investigated to gain insight into the role of intramolecular energy and charge transfer processes in radical production and decay. Model calculations based on a thermal-spike approximation are presented and their limitations for predicting the orientation dependence of radical yields observed after neutron irradiation (see C. M. Arroyo et al. Int. J. Radiat. Biol. 50, 789 (1986)) are discussed. A more mechanistic model based on the high mobility of excess electrons in hydrated DNA (D. van Lith et al. J. Chem. Soc. Faraday Trans. 1, 82, 2933 (1986)) is outlined.

Neural Foundations of Variability in Attachment

2017 ◽  
Author(s):  
Allyson J. Bennett ◽  
William D. Hopkins ◽  
Ruth Feldman ◽  
Valeria Gazzola ◽  
Jay Giedd ◽  
...  
Keyword(s):  
Brain Development ◽  
Animal Studies ◽  
Experimental Studies ◽  
Theory Development ◽  
Single Type ◽  
Negative Consequences ◽  
Cultural Contexts ◽  
The Social ◽  
Insight Into

Neuroscience offers insight into processes that support the development of the social brain within the cultural contexts that permit attachment relationships to form. Both human and nonhuman animal studies are critical to inform theory development and hypothesis testing via descriptive and experimental studies. A scientifically valid evolutionary theory is necessary to account for the remarkable diversity of parenting systems across human and many nonhuman animals. This chapter examines the neural foundations of attachment and poses critical questions that relate to the initiation of this relationship: How does attachment interface with brain development? What is the interplay between attachment and brain development (including elements of bidirectionality)? Are there negative consequences associated with variation in attachment, and are they reversible? Rather than conceptualizing attachment in terms of a single type of relationship, or a rigid developmental channel, this chapter proposes that an expanded consideration of variation is necessary to understand the neural foundations of infant-caregiver relationships, and the role of those relationships in developing competence across the life span. This approach will permit identification of common neurobiological elements of attachment as well as the remarkable plasticity and diversity within and across individuals, cultures, and species.

scholarly journals Effect of the Air-Water Interface on the Conformation of Amyloid Beta

2020 ◽  
Author(s):  
Suman Samantray ◽  
David Cheung
Keyword(s):  
Conformational Change ◽  
Amyloid Beta ◽  
Md Simulation ◽  
Experimental Studies ◽  
Water Interface ◽  
Air Water Interface ◽  
Protein Conformational Change ◽  
Protein Fibrillation ◽  
Insight Into

Using MD simulation the conformation of the fibril forming protein amyloid beta at the air-water interface. It is found that adsorption at the air-water interface induces the formation of aggregation prone alpha-helical conformations, consistent with experimental studies of amyloid beta. Adsorption on the air-water interface also reduces the number of distinct conformations that the protein exhibits. This provides insight into the role of protein conformational change into the enhancement of protein fibrillation at interfaces.

scholarly journals Effect of the Air-Water Interface on the Conformation of Amyloid Beta

2020 ◽  
Author(s):  
Suman Samantray ◽  
David Cheung
Keyword(s):  
Conformational Change ◽  
Amyloid Beta ◽  
Md Simulation ◽  
Experimental Studies ◽  
Water Interface ◽  
Air Water Interface ◽  
Protein Conformational Change ◽  
Protein Fibrillation ◽  
Insight Into

Using MD simulation the conformation of the fibril forming protein amyloid beta at the air-water interface. It is found that adsorption at the air-water interface induces the formation of aggregation prone alpha-helical conformations, consistent with experimental studies of amyloid beta. Adsorption on the air-water interface also reduces the number of distinct conformations that the protein exhibits. This provides insight into the role of protein conformational change into the enhancement of protein fibrillation at interfaces.

scholarly journals Evaluating the Protective Effect of a Combination of Curcumin and Selenium-L-Methionine on Radiation Induced Dual Oxidase Upregulation

2018 ◽  
Vol 24 (4) ◽  
pp. 340-345 ◽  
Author(s):  
Peyman Amini ◽  
Saeed Rezapoor ◽  
Dheyauldeen Shabeeb ◽  
Ahmed Eleojo Musa ◽  
Masoud Najafi ◽  
...  
Keyword(s):  
Ionizing Radiation ◽  
Atomic Bomb ◽  
Heart Diseases ◽  
Experimental Studies ◽  
Epidemiological Studies ◽  
Left Breast ◽  
Interleukin 4 ◽  
Breast Cancer Patients ◽  
Radiation Induced

Background: Epidemiological studies have shown an increased incidence of heart diseases among survivors of Chernobyl disaster as well as Hiroshima and Nagasaki atomic bomb explosion. Similar results were observed for lung and left breast cancer patients. Experimental studies have proposed the chronic upregulation of some pro-inflammatory and pro-fibrotic cytokines. Recent studies have shown that upregulation of pro-oxidant enzymes play a key role in the development of late effects of ionizing radiation such as fibrosis. Interleukin-4 (IL-4) and Interleukin-13 (IL-13) are two important cytokines that have shown ability to induce production of free radicals through dual oxidases (Duox) i.e. Duox1 and Duox2. In this study, we aimed to detect the expression of IL-4 receptor-a1 (IL-4Ra1), IL-13 receptor-a2 (IL-13Ra2), Duox1 and Duox2 genes following irradiation of rat’s heart. In addition, we evaluated the possible role of the combination of curcumin and selenium-L-methionine on the regulation of these genes. Methods: Twenty rats were divided into 4 groups as follows; G1: control; G2: treatment with the combination of curcumin and selenium-L-methionine; G3: radiation; G4: radiation plus treatment with the combination of curcumin and selenium-L-methionine. Rats were sacrificed 10 weeks after irradiation for detecting the expression of IL-4Ra1, IL-13Ra2, Duox1 and Duox2. Results: Results showed that exposure to ionizing radiation caused upregulation of IL-4Ra1 by more than 4-fold as well as Duox1 and Duox2 by more than 5-fold. However, results showed no detectable expression for IL-13Ra2. Treatment with the combination of curcumin and selenium-L-methionine could attenuate the upregulation of all genes. Conclusion: This study has shown that exposing rat’s heart tissues to radiation leads to chronic upregulation of IL-4Ra1, Duox1 and Duox2 as well as pro-oxidant enzymes. Treatment with the combination of curcumin and selenium-L-methionine showed ability to attenuate the upregulation of these genes.

scholarly journals Spectral signatures of charge transfer in assemblies of molecularly-linked plasmonic nanoparticles

2017 ◽  
Vol 31 (24) ◽  
pp. 1740002 ◽  
Author(s):  
Sarah Lerch ◽  
Björn M. Reinhard
Keyword(s):  
Charge Transfer ◽  
Self Assembly ◽  
Experimental Studies ◽  
Blue Shift ◽  
Spectral Signatures ◽  
Sensor Platform ◽  
Interparticle Separation ◽  
Plasmon Spectrum ◽  
Significant Blue Shift

Self-assembly of functionalized nanoparticles (NPs) provides a unique class of nanomaterials for exploring and utilizing quantum-plasmonic effects that occur if the interparticle separation between NPs approaches a few nanometers and below. We review recent theoretical and experimental studies of plasmon coupling in self-assembled NP structures that contain molecular linkers between the NPs. Charge transfer through the interparticle gap of an NP dimer results in a significant blue-shift of the bonding dipolar plasmon (BDP) mode relative to classical electromagnetic predictions, and gives rise to new coupled plasmon modes, the so-called charge transfer plasmon (CTP) modes. The blue-shift of the plasmon spectrum is accompanied by a weakening of the electromagnetic field in the gap of the NPs. Due to an optical far-field signature that is sensitive to charge transfer across the gap, plasmonic molecules represent a sensor platform for detecting and characterizing gap conductivity in an optical fashion and for characterizing the role of molecules in facilitating the charge transfer across the gap.

scholarly journals The effect of Cr alloying on defect migration at Ni grain boundaries

2022 ◽  
Author(s):  
Blas P. Uberuaga ◽  
Pauline Simonnin ◽  
Kevin M. Rosso ◽  
Daniel K. Schreiber ◽  
Mark Asta
Keyword(s):  
Grain Boundary ◽  
Mass Transport ◽  
Grain Boundaries ◽  
Experimental Studies ◽  
Boundary Mobility ◽  
Defect Migration ◽  
Grain Boundary Mobility ◽  
Tilt Boundaries ◽  
Insight Into

AbstractMass transport along grain boundaries in alloys depends not only on the atomic structure of the boundary, but also its chemical make-up. In this work, we use molecular dynamics to examine the effect of Cr alloying on interstitial and vacancy-mediated transport at a variety of grain boundaries in Ni. We find that, in general, Cr tends to reduce the rate of mass transport, an effect which is greatest for interstitials at pure tilt boundaries. However, there are special scenarios in which it can greatly enhance atomic mobility. Cr tends to migrate faster than Ni, though again this depends on the structure of the grain boundary. Further, grain boundary mobility, which is sometimes pronounced for pure Ni grain boundaries, is eliminated on the time scales of our simulations when Cr is present. We conclude that the enhanced transport and grain boundary mobility often seen in this system in experimental studies is the result of non-equilibrium effects and is not intrinsic to the alloyed grain boundary. These results provide new insight into the role of grain boundary alloying on transport that can help in the interpretation of experimental results and the development of predictive models of materials evolution.

scholarly journals The role of «metabolic memory» mechanisms in the development and progression of vascular complications of diabetes mellitus

10.14341/7674 ◽  
2017 ◽  
Vol 20 (2) ◽  
pp. 126-134
Author(s):  
Alexander Alexandrovich Chernikov ◽  
Anastasia Sergeevna Severina ◽  
Minara Shamhalovna Shamhalova ◽  
Marina Vladimirovna Shestakova
Keyword(s):  
Diabetes Mellitus ◽  
Experimental Studies ◽  
Vascular Complications ◽  
Late Complications ◽  
Metabolic Memory ◽  
Delayed Effect ◽  
Glycation End Products ◽  
Point Of No Return ◽  
Insight Into

The study of diabetes mellitus (DM), its complications and related pathologies has been continuously performed for many years; however, despite the substantial work and outstanding achievements in studying the mechanisms of DM development and the success of new medicinal products for controlling glycaemia, the problems associated with the late complications of DM continue to increase. The importance of glycaemic control in the early stages of DM for the development of complications is seen only after a sufficiently long period of observation. Such a delayed effect of primary good or unsatisfactory metabolic control, which shapes the patients clinical fate to a greater extent, is termed metabolic memory. The disorders developed under the influence of hyperglycaemia persist for long periods after the normalisation of carbohydrate metabolism; moreover, the effect of previous hyperglycaemia extends over the next 20 and even 30 years. Current research is focused on the possible mechanisms of metabolic memory development, including oxidative stress, advanced glycation end products and epigenetic mechanisms. This research will provide insight into potential markers for the early development and progression of vascular complications and new therapeutic possibilities for the future. However, determining the probable point of no return is more important, which implies that a point exists; after this point is crossed, the progression of vascular complications associated with DM cannot be prevented or reversed. The results of numerous experimental studies demonstrate that the prerequisite components of metabolic memory can be used as potential markers of the progression of DM complications, and may be potential therapeutic targets.

scholarly journals Single-Particle and Collective Structures in Neutron-Rich Sr Isotopes

Universe ◽  
2021 ◽  
Vol 8 (1) ◽  
pp. 23
Author(s):  
Kamila Sieja
Keyword(s):  
Shell Model ◽  
Ground State ◽  
Experimental Studies ◽  
Low Energy ◽  
Model Description ◽  
Sr Isotopes ◽  
Model Calculations ◽  
Spectroscopic Factors ◽  
Monte Carlo Shell Model ◽  
Insight Into

Neutron-rich Sr nuclei around N=60 exhibit a sudden shape transition from a spherical ground state to strongly prolate-deformed. Recently, much new insight into the structure of Sr isotopes in this region has been gained through experimental studies of the excited levels, transition strengths, and spectroscopic factors. In this work, a “classic” shell model description of strontium isotopes from N=50 to N=58 is provided, using a natural valence space outside the 78Ni core. Both even–even and even–odd isotopes are addressed. In particular, spectroscopic factors are computed to shed more light on the structure of low-energy excitations and their evolution along the Sr chain. The origin of deformation at N=60 is mentioned in the context of the present and previous shell model and Monte Carlo shell model calculations.

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