scholarly journals Relating Linear Energy Transfer to the Formation and Resolution of DNA Repair Foci After Irradiation with Equal Doses of X-ray Photons, Plateau, or Bragg-Peak Protons

2018 ◽  
Vol 19 (12) ◽  
pp. 3779 ◽  
Author(s):  
Sebastian Oeck ◽  
Klaudia Szymonowicz ◽  
Gesa Wiel ◽  
Adam Krysztofiak ◽  
Jamil Lambert ◽  
...  
Keyword(s):  
Dna Damage ◽  
Energy Transfer ◽  
Linear Energy Transfer ◽  
Bragg Peak ◽  
Cultured Cells ◽  
Human Cancer ◽  
Proton Beam Therapy ◽  
X Ray ◽  
Cellular Repair ◽  
Set Up

Proton beam therapy is increasingly applied for the treatment of human cancer, as it promises to reduce normal tissue damage. However, little is known about the relationship between linear energy transfer (LET), the type of DNA damage, and cellular repair mechanisms, particularly for cells irradiated with protons. We irradiated cultured cells delivering equal doses of X-ray photons, Bragg-peak protons, or plateau protons and used this set-up to quantitate initial DNA damage (mainly DNA double strand breaks (DSBs)), and to analyze kinetics of repair by detecting γH2A.X or 53BP1 using immunofluorescence. The results obtained validate the reliability of our set-up in delivering equal radiation doses under all conditions employed. Although the initial numbers of γH2A.X and 53BP1 foci scored were similar under the different irradiation conditions, it was notable that the maximum foci level was reached at 60 min after irradiation with Bragg-peak protons, as compared to 30 min for plateau protons and photons. Interestingly, Bragg-peak protons induced larger and irregularly shaped γH2A.X and 53BP1 foci. Additionally, the resolution of these foci was delayed. These results suggest that Bragg-peak protons induce DNA damage of increased complexity which is difficult to process by the cellular repair apparatus.

scholarly journals The effect of low LET (Linear Energy Transfer) ionizing radiation to catalase activity of wistar’s submandibular gland

2016 ◽  
Vol 1 (3) ◽  
pp. 145
Author(s):  
Nevy T. Putri ◽  
Sarianoferni Sarianoferni ◽  
Endah Wahjuningsih
Keyword(s):  
Energy Transfer ◽  
Ionizing Radiation ◽  
Submandibular Gland ◽  
Rattus Norvegicus ◽  
Catalase Activity ◽  
Linear Energy Transfer ◽  
Submandibular Salivary Gland ◽  
X Rays ◽  
X Ray ◽  
Bonferroni Test

Intraoral periapical radiograph examination is the additional examination which is the most widely used in Dentistry. This radiograph examination using an x-ray ionizing radiation with low LET (Linear Energy Transfer), and may affect submandibular salivary gland. Ionizing radiation exposure can cause damage by inducing a series of changes at the molecular and cellular level. This study aimed to prove the effects of x-ray ionizing radiation with low LET towards the catalase activity of Rattus norvegicus strain Wistar’s submandibular gland. The subjects were 28 male Wistar rats and divided into 4 groups (n=7). Three groups were exposed 4, 8 and 14 times to radiation with 0.002 µSv for each exposure. The catalase activity of each rat was examined by a spectrophotometer. Data were analyzed using one-way ANOVA followed by Bonferroni test. The results showed the average of catalase activity on Wistar rat’s submandibular gland, respectively for: 0.150±0.0895 (KK), 0.1405±0.0607 (K1), 0.1228±0.0290 (K2), 0.1227±0.0556 (K3). Data showed significant differences of catalase activity between test groups, but showed not significant differences of catalase activity between each groups of Rattus norvegicus strain Wistar’s submandibular gland. In this study concluded decreased catalase activity of Rattus norvegicus strain Wistar’s submandibular gland resulting from x-rays ionizing radiation by 4 times, 8 times and 14 times exposures.

scholarly journals The Radiobiological Effects of Proton Beam Therapy: Impact on DNA Damage and Repair

Cancers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 946 ◽  
Author(s):  
Eirini Terpsi Vitti ◽  
Jason L Parsons
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Proton Beam ◽  
Bragg Peak ◽  
Proton Beam Therapy ◽  
High Energy ◽  
High Let ◽  
Repair Pathways ◽  
Radiobiological Effects ◽  
Photon Radiotherapy

Proton beam therapy (PBT) offers significant benefit over conventional (photon) radiotherapy for the treatment of a number of different human cancers, largely due to the physical characteristics. In particular, the low entrance dose and maximum energy deposition in depth at a well-defined region, the Bragg peak, can spare irradiation of proximal healthy tissues and organs at risk when compared to conventional radiotherapy using high-energy photons. However, there are still biological uncertainties reflected in the relative biological effectiveness that varies along the track of the proton beam as a consequence of the increases in linear energy transfer (LET). Furthermore, the spectrum of DNA damage induced by protons, particularly the generation of complex DNA damage (CDD) at high-LET regions of the distal edge of the Bragg peak, and the specific DNA repair pathways dependent on their repair are not entirely understood. This knowledge is essential in understanding the biological impact of protons on tumor cells, and ultimately in devising optimal therapeutic strategies employing PBT for greater clinical impact and patient benefit. Here, we provide an up-to-date review on the radiobiological effects of PBT versus photon radiotherapy in cells, particularly in the context of DNA damage. We also review the DNA repair pathways that are essential in the cellular response to PBT, with a specific focus on the signaling and processing of CDD induced by high-LET protons.

scholarly journals Measurement of complex DNA damage induction and repair in human cellular systems after exposure to ionizing radiations of varying linear energy transfer (LET)

2016 ◽  
Vol 50 (sup1) ◽  
pp. S64-S78 ◽  
Author(s):  
Zacharenia Nikitaki ◽  
Vladimir Nikolov ◽  
Ifigeneia V. Mavragani ◽  
Emil Mladenov ◽  
Anastasios Mangelis ◽  
...  
Keyword(s):  
Dna Damage ◽  
Energy Transfer ◽  
Linear Energy Transfer ◽  
Cellular Systems ◽  
Ionizing Radiations

scholarly journals Mechanisms of resistance to high and low linear energy transfer radiation in myeloid leukemia cells

Blood ◽  
2012 ◽  
Vol 120 (10) ◽  
pp. 2087-2097 ◽  
Author(s):  
Kurtis J. Haro ◽  
Andrew C. Scott ◽  
David A. Scheinberg
Keyword(s):  
Dna Damage ◽  
Energy Transfer ◽  
Linear Energy Transfer ◽  
Myeloid Leukemia ◽  
Hl60 Cell ◽  
Cross Resistance ◽  
Mechanisms Of Resistance ◽  
Acute Leukemias ◽  
Γ Rays ◽  
Α Particles

Abstract Low linear energy transfer (LET) ionizing radiation (IR) is an important form of therapy for acute leukemias administered externally or as radioimmunotherapy. IR is also a potential source of DNA damage. High LET IR produces structurally different forms of DNA damage and has emerged as potential treatment of metastatic and hematopoietic malignancies. Therefore, understanding mechanisms of resistance is valuable. We created stable myeloid leukemia HL60 cell clones radioresistant to either γ-rays or α-particles to understand possible mechanisms in radioresistance. Cross-resistance to each type of IR was observed, but resistance to clustered, complex α-particle damage was substantially lower than to equivalent doses of γ-rays. The resistant phenotype was driven by changes in: apoptosis; late G2/M checkpoint accumulation that was indicative of increased genomic instability; stronger dependence on homology-directed repair; and more robust repair of DNA double-strand breaks and sublethal-type damage induced by γ-rays, but not by α-particles. The more potent cytotoxicity of α-particles warrants their continued investigation as therapies for leukemia and other cancers.

scholarly journals Degradation of 4-Chlorophenol by Gamma Radiation of 137Cs and X-rays

2019 ◽  
Vol 54 (3) ◽  
Author(s):  
Julio César González-Juárez ◽  
Jaime Jiménez-Becerril ◽  
Jesús Cejudo-Álvarez
Keyword(s):  
Energy Transfer ◽  
Gamma Radiation ◽  
Crystalline Structure ◽  
Linear Energy Transfer ◽  
The Other ◽  
X Rays ◽  
137Cs Source ◽  
X Ray ◽  
Radiolytic Degradation ◽  
Radiation Sources

This paper presents results of radiolytic degradation of 4-chlorophenol in the presence of TiO2, Al2O3, y SiO2, using different radiation sources than 60Co, which is so common in this type of experiment. The radiation sources used were X-rays with energy of 100 keV and radiation from 137Cs (662 keV). After irradiation with a dose of 50 cGy X-ray and TiO2 obtained a degradation of about 5%, no degradation was obtained with 137Cs source and other oxides. This may be due to the fact that X-rays have a linear energy transfer (LET) greater value, and in the case of TiO2 present a crystalline structure, whereas the other two oxides are amorphous. Both characteristics result in better formation of a reactive species that allows the degradation of the compound.

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