ABSTRACT
In this work we review all the available experimental neutron data for the (7)Li(p,n) reaction near threshold which is necessary to obtain an accurate source model for Monte Carlo simulations in Boron Neutron Capture Therapy. Scattered published experimental results such as cross sections, differential neutron yields and total yields were collected and analyzed, exploring the sensitivity of the fitting parameters to the different possible variables and deriving a consistent working set of parameters to evaluate the neutron source near threshold.
Subject(s)
Beryllium/radiation effects , Boron Neutron Capture Therapy/instrumentation , Lithium/radiation effects , Models, Statistical , Particle Accelerators/instrumentation , Beryllium/chemistry , Computer Simulation , Computer-Aided Design , Equipment Design , Equipment Failure Analysis , Isotopes/chemistry , Isotopes/radiation effects , Lithium/chemistry , Neutrons , Radiometry , Radiotherapy DosageABSTRACT
PURPOSE: The aim of this study was to evaluate the induction and rejoining of DNA double strand breaks (DSBs) in melanoma cells exposed to low and high linear energy transfer (LET) radiation. METHODS AND MATERIALS: DSBs and survival were determined as a function of dose in melanoma cells (B16-F0) irradiated with monoenergetic proton and lithium beams and with a gamma source. Survival curves were obtained by clonogenic assay and fitted to the linear-quadratic model. DSBs were evaluated by the detection of phosphorylated histone H2AX (gammaH2AX) foci at 30 min and 6 h post-irradiation. RESULTS: Survival curves showed the increasing effectiveness of radiation as a function of LET. gammaH2AX labeling showed an increase in the number of foci vs. dose for all the radiations evaluated. A decrease in the number of foci was found at 6 h post-irradiation for low LET radiation, revealing the repair capacity of DSBs. An increase in the size of gammaH2AX foci in cells irradiated with lithium beams was found, as compared with gamma and proton irradiations, which could be attributed to the clusters of DSBs induced by high LET radiation. Foci size increased at 6 h post-irradiation for lithium and proton irradiations in relation with persistent DSBs, showing a correlation with surviving fraction. CONCLUSIONS: Our results showed the response of B16-F0 cells to charged particle beams evaluated by the detection of gammaH2AX foci. We conclude that gammaH2AX foci size is an accurate parameter to correlate the rejoining of DSBs induced by different LET radiations and radiosensitivity.
Subject(s)
DNA Breaks, Double-Stranded , DNA Repair , Histones/metabolism , Linear Energy Transfer , Melanoma, Experimental/radiotherapy , Biomarkers/analysis , Biomarkers/metabolism , Cell Survival , Dose-Response Relationship, Radiation , Histones/analysis , Humans , Lithium/therapeutic use , Melanoma, Experimental/genetics , Melanoma, Experimental/metabolism , Phosphorylation , Proton Therapy , Radiation Tolerance , Radioisotopes/therapeutic useABSTRACT
The effects of copper and cadmium on metabolism through the pentose phosphate pathway were evaluated in Bufo arenarum toad ovary. The effects of the two metals on dehydrogenases from this pathway were evaluated by three experiments: (1) in samples obtained from control females with addition of the metals to the reaction mixture (in vitro), (2) in samples obtained from control females and after long-term exposure of females to 4 and 100 microg/L of Cu or Cd in the incubation media (in vitro after exposure to the metals in vivo), and (3) 14CO2 production through the pentose phosphate pathway was evaluated after [U-14C]glucose microinjection on ovulated oocytes (in vivo after microinjection of the metals). Results from (1) evidenced inhibition of both enzyme activities but only above 1.5 mM Cu and Cd added to the reaction mixture. In (2) both glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase activities decreased in samples from the ovaries of females exposed in vivo to Cu, in a concentration-dependent manner (up to 90% in females exposed to 100 microg/L Cu: 2.12 +/- 1.57 NADPH micromol/min microg protein x 10(-5) vs 19.97 +/- 8.54 in control females). Cd treatment of the toads only rendered an inhibitory effect on 6-phosphogluconate dehydrogenase activity after exposure to 4 microg/L of the bivalent cation. (3) In vivo 14CO2 evolution significantly decreased in oocytes coinjected with 6.3 x 10(-3) mM Cu (calculated intracellular final concentration of the metal injected) and radioactive glucose. Cu and Cd concentration in samples from exposed females were always under detection limit by particle-induced X-ray emission. The results presented here are in agreement with a role for both glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase activities determination as biomarkers of effect and exposure for Cu but not for Cd toxicity.
Subject(s)
Biomarkers/analysis , Bufonidae/physiology , Cadmium/toxicity , Copper/toxicity , Glucosephosphate Dehydrogenase/pharmacology , Pentose Phosphate Pathway/drug effects , Pentose Phosphate Pathway/physiology , Phosphogluconate Dehydrogenase/pharmacology , Water Pollutants/toxicity , Animals , Carbon Dioxide/analysis , Female , Glucose/metabolism , Ovary/physiologyABSTRACT
La técnica PIXE (Particle Induced X-Ray Emission), una técnica analítica multielemental de alta sensibilidad fue puesta a punto en la Argentina utilizando haces de iones pesados provistos por el acelerador Tandem TANDAR para su uso en la determinación de trazas. En este trabajo se discuten características generales de la técnica, se pasa revista a las aplicaciones implementadas localmente enfatizando aquellas relacionadas con problemas ambientales, como la determinación de la contaminación del aire, agua y suelo; y se la compara con otras técnicas analíticas
Subject(s)
Water Microbiology , Water Pollution , Environmental Pollution , X-Rays , Water Microbiology , Air Analysis , Soil AnalysisABSTRACT
La técnica PIXE (Particle Induced X-Ray Emission), una técnica analítica multielemental de alta sensibilidad fue puesta a punto en la Argentina utilizando haces de iones pesados provistos por el acelerador Tandem TANDAR para su uso en la determinación de trazas. En este trabajo se discuten características generales de la técnica, se pasa revista a las aplicaciones implementadas localmente enfatizando aquellas relacionadas con problemas ambientales, como la determinación de la contaminación del aire, agua y suelo; y se la compara con otras técnicas analíticas
