The development of novel technologies for the safe and effective delivery of radiation is critical to advancing the field of radiation oncology. The Emerging Technology Committee of the American Society for Therapeutic Radiology and Oncology appointed a Task Group...
Radiation Research
CT guidance is needed to achieve reproducible positioning of the mouse head for repeat precision cranial irradiation
To study the effects of cranial irradiation, we have constructed an all-plastic mouse bed equipped with an immobilizing head holder. The bed integrates with our in-house Small Animal Radiation Research Platform (SARRP) for precision focal irradiation experiments and...
Recognition of O6MeG lesions by MGMT and mismatch repair proficiency may be a prerequisite for low-dose radiation hypersensitivity.
Low-dose hyper-radiosensitivity (HRS) is the phenomenon whereby cells exposed to radiation doses of less than ∼0.5 Gy exhibit increased cell killing relative to that predicted from back-extrapolating high-dose survival data using a linear-quadratic model. While the exact mechanism remains to be elucidated, the involvement of several molecular repair pathways has been documented. These processes in turn are also associated with the response of cells to O6-methylguanine (O6MeG) lesions. We propose a model in which the level of low-dose cell killing is determined by the efficiency of both pre-replicative repair by the DNA repair enzyme O6-methylguanine methyltransferase (MGMT) and post-replicative repair by the DNA mismatch repair (MMR) system. We therefore hypothesized that the response of cells to low doses of radiation is dependent on the expression status of MGMT and MMR proteins. MMR (MSH2, MSH6, MLH1, PMS1, PMS2) and MGMT protein expression signatures were determined in a panel of normal (PWR1E, RWPE1) and malignant (22RV1, DU145, PC3) prostate cell lines and correlated with clonogenic survival and cell cycle analysis. PC3 and RWPE1 cells (HRS positive) were associated with MGMT and MMR proficiency, whereas HRS negative cell lines lacked expression of at least one (MGMT or MMR) protein. MGMT inactivation had no significant effect on cell survival. These results indicate a possible role for MMR-dependent processing of damage produced by low doses of radiation.
Lynn Martin, Brian Marples, Mary Coffey, Mark Lawler, Donal Hollywood, and Laure Marignol
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Courtship raises male fertilization success through post-mating sexual selection in a spider.
Courtship is well known for its positive effects on mating success. However, in polyandrous species, sexual selection continues to operate after copulation. Cryptic female choice is expected under unpredictable mating rates in combination with sequential mate encounters. However, there are very few accounts of the effects of courtship on cryptic female choice, and the available evidence is often correlative.
Mature Argiope bruennichi females are always receptive and never attack or reject males before mating, although sexual cannibalism after mating occurs regularly. Still, males usually perform an energetic vibratory display prior to copulation. We tested the hypothesis that beneficial effects of courtship arise cryptically, during or after mating, resulting in increased paternity success under polyandry. Manipulating courtship duration experimentally, we found that males that mated without display had a reduced paternity share even though no differences in post-copulatory cannibalism or copulation duration were detected. This suggests that the paternity advantage associated with courtship arose through female-mediated processes after intromission, meeting the definition of cryptic female choice.
Jutta M Schneider and Kristiani Lesmono
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Towards real-time radiation therapy: GPU accelerated superposition/convolution.
We demonstrate the use of highly parallel graphics processing units (GPUs) to accelerate the superposition/convolution (S/C) algorithm to interactive rates while reducing the number of approximations. S/C first transports the incident fluence to compute the total...
A comprehensive system for dosimetric commissioning and Monte Carlo validation for the small animal radiation research platform
Our group has constructed the small animal radiation research platform (SARRP) for delivering focal, kilo-voltage radiation to targets in small animals under robotic control using cone-beam CT guidance. The present work was undertaken to support the SARRP's treatment...
Image Guided Small Animal Radiation Research Platform: Calibration of Treatment Beam Alignment
Small animal research allows detailed study of biological processes, disease progression, and response to therapy, with the potential to provide a natural bridge to the clinical environment. The Small Animal Radiation Research Platform (SARRP) is a portable system for...
The 2007 AAPM response to the CRCPD request for recommendations for the CRCPD’s model regulations for electronic brachytherapy (2009)
The American Association of Physicists in Medicine (AAPM) formed a Task Group under the Unconventional Brachytherapy Working Group of the Brachytherapy Subcommittee and the Radiation Safety Subcommittee of the Therapy Physics Committee (TPC). This Task Group, TG-152,...
Precision radiotherapy for small animal research
Preclinical research using well characterized small animal models has provided tremendous benefits to medical research, enabling low cost, large scale trials with high statistical significance of observed effects. The goal of the Small Animal Radiation Research...