Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.3.1.51 (HDR)
 605 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Recent data suggest that aberrant function of the wild type p53 protein (WTp53) may alter cellular survival following DNA damage through cellular pathways involving apoptosis and cell-cycle checkpoints, but little is known concerning it's possible role in DNA repair. In the present study, the ionizing radiation sensitivity was determined for a series of rat embryo fibroblast (REF) cell lines transfected with an activated form of the H-ras oncogene alone, or in combination with a variety of missense-mutant p53 (MTp53) alleles. Transformed REF clones which expressed exogenous MTp53 and p21ras proteins (CLASS II clones) were generally radioresistant in culture as determined by higher values for the surviving fraction after 2 Gy (SF2 value) and the radiation dose required to reduce survival to a fraction of 0.1 (D10 value), compared either to transformed REF clones expressing p21ras protein alone (CLASS I clones), or to non-transfected REF control cell lines expressing baseline endogenous levels of p21ras and WTp53 protein. The increased radioresistance observed in the CLASS II clones (following both HDR- and LDR-irradiation), was significantly correlated with increased expression of MTp53 protein, and a decreased radiation-induced G1 arrest response. The variability observed in clonogenic radiosensitivity among REF clones was not explained by differential radiation-induced apoptosis. Using the Comet assay performed after continuous low dose-rate (LDR)-irradiation, MTp53-expressing REF clones were also found to be more proficient at the rejoining of DNA double-strand breaks (DNA-dsb), compared to WTp53-expressing REF clones. These results suggest that an enhanced DNA and cellular repair capacity may, in part, explain the increased radiation survival observed in some MTp53-expressing transformed fibroblasts and tumours.
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PMID:Radioresistant MTp53-expressing rat embryo cell transformants exhibit increased DNA-dsb rejoining during exposure to ionizing radiation. 958 77

There were analyzed dosimetric plans obtained during the first session of HDR brachytherapy in 70 primary prostate cancer patients. Assessments were subjected to dosimetric parameters (V100, D90, D2cc, D10) obtained after implantation in the prostate needle-intrastats estimated before and after adjustment of contours of the prostate and surrounding organs at risk. It was showed that in most cases they were matched to the intended dosimetric parameters: V100 average--94,1% (V100 more than 90% in 97.2% of cases), D90 average--104,3% (D90 100% achieved in 95.7% of cases). In contrast, when using primary plan dosimetry without estimation of changing the geometry of the prostate and organs at risk in 38.6% patients V100 value was below 80%, in 41.4% patients--was in the range from 80% to 90%. In 24.3% patients index D90 did not exceed 80%, in 31.4% patients determined in the range from 80% to 90% and in 24.3% patients was close to 100%. In the absence of correction of contours of the urethra and the prostate in 18% patients the value of D10 for the urethra was higher border 115% and could increase to critical 189%.
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PMID:[High-dose brachytherapy for prostate cancer in real time using 192-IR (specifics of dosimetric planning)]. 2601 59

During prostate cancer treatment with HDR brachytherapy, catheters are inserted into the prostate. Between planning and treatment, catheters may move inferiorly due to edema. If undetected, treatment proceeds without correcting the catheter displacement, and an incorrect treatment is delivered. The purpose of this study was to investigate the consequences of catheter displacement on prostate coverage and critical structure avoidance. Ten patient plans were selected in which movement of the catheters had been observed. The original treatment plan, generated using Nucletron PLATO (ver. 14.3.2), was adjusted introducing inferior catheter offsets of 5, 10, 20, and 30 mm. The original treatment dwell times were re-entered into the offset plans to determine the consequences of the displacement. DVH data was calculated for the prostate, rectum, urethra, and bladder. Prostate V100 decreased from 99% to 36% over the ten patients studied. For the urethra, the D10 increased (114.1% to 128.2%), as did the V125 (2.7% to 12.8%). In the rectum the V75 initially increased as the catheters shifted inferiorly, but dropped as the shift increased beyond 10 mm. In the penile bulb the V75 increased as a function of shift (from 2.1% to 44.8%). Every effort should be made to ensure that the catheters do not move during prostate treatment. A small shift, 5 mm, would result in a small deviation of the dose distribution. In this case a re-optimization of the plan is unnecessary. Larger shifts will have a serious impact on the dose delivered to the prostate and to sensitive normal structures.
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PMID:Sci-Sat AM(2): Brachy-09: Investigation of catheter displacement in HDR prostate brachytherapy. 2851 78