RECOVERY FROM RADIATION-INDUCED LETHAL SECTORING IN YEAST

1968 ◽  
Vol 10 (2) ◽  
pp. 283-293 ◽  
Author(s):  
A. P. James ◽  
Alexa S. Saunders
Keyword(s):  
Gradual Decline ◽  
X Ray ◽  
Post Irradiation ◽  
Lethal Damage ◽  
Radiation Induced ◽  
Lines Of Descent ◽  
Successive Generations

Recovery from the X-ray-induced damage responsible for lethal sectoring was investigated in diploid yeast. Lethal sectoring, an important factor in lethal damage, is characterized by the sporadic appearance of clusters of dead cells in earlier post-irradiation vegetative generations of surviving cells. Recovery from the instability responsible for sectoring was evident in a gradual decline in the frequency with which sectors were initiated through successive generations. This decline was shown to result from the fact that unstable cells, though able to persist indefinitely, had a propensity for reversion as well as for lethal sectoring. Some lines of descent from unstable cells lost their ability to revert without losing their ability to produce lethal sectors.

ATM and RAD51 Repair Pathways in Human Lymphocytes Irradiated with 70 MeV Therapeutic Proton Beam

2021 ◽  
Author(s):  
Agnieszka Panek ◽  
Justyna Miszczyk
Keyword(s):  
Proton Beam ◽  
Human Lymphocytes ◽  
Strand Break ◽  
Double Strand Break ◽  
Double Strand Break Repair ◽  
X Rays ◽  
X Ray ◽  
Post Irradiation ◽  
Repair Protein ◽  
Radiation Induced

The repair of radiation-induced DNA damage is a key factor differentiating patients in terms of the therapeutic efficacy and toxicity to surrounding normal tissue. Proton energy substantially determines the types of cancers that can be treated. The present work investigated the DNA double-strand break repair systems, represented by phosphorylated ATM and Rad51. The status of proton therapy energy used to treat major types of cancer is summarized. Here, human lymphocytes from eight healthy donors (male and female) were irradiated with a spread-out Bragg peak using a therapeutic 70 MeV proton beam or with reference X rays. For both types of radiation, the kinetics of pATM and Rad51 repair protein activation (0–24 h) were estimated as determinants of homologous and non-homologous double-strand break repair. Additionally, γ-H2AX was used as the gold standard marker of double-strand breaks. Our results showed that at 30 min postirradiation there was significantly greater accumulation of γ-H2AX (0.6-fold), pATM (2.0-fold), and Rad51 (0.6-fold) in the proton-irradiated cells compared with the X-ray-treated cells. At 24 h post irradiation, for both types of radiation and all investigated proteins, the foci number was still significantly higher when compared with control. Furthermore, the mean value of pATM and Rad51 repair effectiveness was higher in cells exposed to protons than in cells exposed to X rays; however, the difference was significant only for pATM. The largest inter-individual differences in the repair capabilities were noted for Rad51. The association between the frequency of repair protein foci and the frequency of lymphocyte viability at 1 h post irradiation showed a positive correlation for protons but a negative correlation for X rays. These findings indicate that the accumulation of radiation-induced repair protein foci after proton versus X-ray irradiation differs between patients, consequently affecting the cellular responses to particle therapy and conventional radiation therapy.

X-Ray Induced Inactivation of the Sulfhydryl Enzyme Malate Synthase in the Presence of Various Additives Probing the Extent of Primary and Post-Irradiation Inactivation and Repair by Rapid Screening on the Microlevel

1990 ◽  
Vol 45 (6) ◽  
pp. 645-654 ◽  
Author(s):  
Helmut Durchschlag ◽  
Peter Zipper
Keyword(s):  
Enzymic Activity ◽  
Malate Synthase ◽  
Rapid Screening ◽  
X Ray ◽  
Post Irradiation ◽  
Screening Experiments ◽  
X Irradiation ◽  
Radiation Induced ◽  
Irradiation Period ◽  
Induced Changes

Abstract The sulfhydryl enzyme malate synthase was inactivated by X-irradiation in air-saturated aqueous solution, in the absence or presence of a variety of additives (thiols, antioxienzymes, typical radical scavengers, inorganic salts, buffer components, substrates, products, analogues). Radiation-induced changes of enzymic activity were registered immediately after stop of irradiation and in the post-irradiation period. Repair experiments were initiated by postirradiation addition of dithiothreitol. Additionally, post-irradiation inactivation was modulated by some further additives. Probing the extent of primary and post-irradiation inactivation and repair was accomplished effectively by screening experiments on the microlevel, and by derivation of normalized efficiency parameters which allowed quick comparisons of the various additives with respect to their protective and repair-promotive efficiencies. Correlations between the efficiency parameters were studied by means of binary and ternary diagrams. Most of the substances added before irradiation were found to protect the enzyme against primary and post-irradiation inactivation and to increase the reparability of the enzyme by dithiothreitol, the extent of the effects depending on the nature (and concentration) of the additives used. Our results indicate that both specific protection (by substrates, products, analogues, and by sulfhydryl agents) and scavenging are responsible for the radioprotective efficiencies of the additives.

scholarly journals Radiation-Induced Metabolic Shifts in the Hepatic Parenchyma: Findings from 18F-FDG PET Imaging and Tissue NMR Metabolomics in a Mouse Model for Hepatocellular Carcinoma

Molecules ◽  
2021 ◽  
Vol 26 (9) ◽  
pp. 2573
Author(s):  
Yi-Hsiu Chung ◽  
Cheng-Kun Tsai ◽  
Ching-Fang Yu ◽  
Wan-Ling Wang ◽  
Chung-Lin Yang ◽  
...  
Keyword(s):  
Fdg Pet ◽  
Liver Parenchyma ◽  
Metabolic Alterations ◽  
Nmr Metabolomics ◽  
Post Irradiation ◽  
The Third ◽  
Radiation Induced ◽  
18F Fdg ◽  
The Right ◽  
Over Time

Purpose: By taking advantage of 18F-FDG PET imaging and tissue nuclear magnetic resonance (NMR) metabolomics, we examined the dynamic metabolic alterations induced by liver irradiation in a mouse model for hepatocellular carcinoma (HCC). Methods: After orthotopic implantation with the mouse liver cancer BNL cells in the right hepatic lobe, animals were divided into two experimental groups. The first received irradiation (RT) at 15 Gy, while the second (no-RT) did not. Intergroup comparisons over time were performed, in terms of 18F-FDG PET findings, NMR metabolomics results, and the expression of genes involved in inflammation and glucose metabolism. Results: As of day one post-irradiation, mice in the RT group showed an increased 18F-FDG uptake in the right liver parenchyma compared with the no-RT group. However, the difference reached statistical significance only on the third post-irradiation day. NMR metabolomics revealed that glucose concentrations peaked on day one post-irradiation both, in the right and left lobes—the latter reflecting a bystander effect. Increased pyruvate and glutamate levels were also evident in the right liver on the third post-irradiation day. The expression levels of the glucose-6-phosphatase (G6PC) and fructose-1, 6-bisphosphatase 1 (FBP1) genes were down-regulated on the first and third post-irradiation days, respectively. Therefore, liver irradiation was associated with a metabolic shift from an impaired gluconeogenesis to an enhanced glycolysis from the first to the third post-irradiation day. Conclusion: Radiation-induced metabolic alterations in the liver parenchyma occur as early as the first post-irradiation day and show dynamic changes over time.

Gamma-Ray Radiation-Induced Surface Hydrophobic Effects in Invar Alloy

2012 ◽  
Vol 482-484 ◽  
pp. 1585-1591 ◽  
Author(s):  
Cheng Fu Yang ◽  
Wei Wen Wang ◽  
Hsin Hwa Chen ◽  
Wei Tan Sun ◽  
Chi Lin Shiau ◽  
...  
Keyword(s):  
Radiation Dose ◽  
Structural Changes ◽  
Gamma Ray ◽  
Small Deviation ◽  
Contact Angles ◽  
Invar Alloy ◽  
Hydrophobic Effects ◽  
Post Irradiation ◽  
Radiation Induced ◽  
Gamma Ray Irradiation

In this paper, we report a new phenomenon observed in the gamma-ray radiation-induced hydrophobic effects on an Invar surface: When the Invar alloy is subjected to different doses of gamma-ray irradiation, the contact angle increases with the radiation dose. Invar samples with exposed to a higher dose appear more hydrophobic, but this tendency disappears following post-irradiation etching. The contact angles of the irradiated and etched Invar samples can be restored back to a stable value with small deviation after 30 min of annealing at 150°C. X-ray diffraction (XRD) analysis found no crystalline structural changes. High resolution field emission scanning microscope (FE-SEM) analyses showed that irradiation might induce crack-like surfaces which could be removed at higher radiation dose in the following acid etchings. It is believed that the chemical bonds of Invar oxide on the surface were broken by the gamma-ray irradiation, thus raising the likelihood of binding with free ions in the air and resulting in the exclusion of the hydrophilic OH bonds, leaving a hydrophobic post-irradiation Invar surface.

G0Cell Cycle Arrest Alone is Insufficient for Enabling the Repair of Ionizing Radiation-Induced Potentially Lethal Damage

2008 ◽  
Vol 170 (2) ◽  
pp. 184-191 ◽  
Author(s):  
Chris van Bree ◽  
Hans M. Rodermond ◽  
Rosemarie ten Cate ◽  
Judith de Vos ◽  
Lukas J. A. Stalpers ◽  
...  
Keyword(s):  
Ionizing Radiation ◽  
Cycle Arrest ◽  
Lethal Damage ◽  
Radiation Induced

X-Ray-Radiation-Induced Cooperative Atomic Movements in Protein

2009 ◽  
Vol 387 (5) ◽  
pp. 1092-1105 ◽  
Author(s):  
Tatiana Petrova ◽  
Vladimir Y. Lunin ◽  
Stephan Ginell ◽  
Isabelle Hazemann ◽  
Krzysztof Lazarski ◽  
...  
Keyword(s):  
X Ray ◽  
Radiation Induced
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