Search results for " Radiation."
showing 10 items of 2788 documents
Erythropoietin restores the anemia-induced reduction in radiosensitivity of experimental human tumors in nude mice
2003
Abstract Purpose The effect of recombinant human erythropoietin (rhEPO) on the radiosensitivity of human tumor xenografts growing in anemic and nonanemic nude mice was studied. Methods and materials Anemia was induced by total body irradiation ([TBI], 2 × 4 Gy) of mice before tumor implantation into the subcutis of the hind leg. The development of anemia was prevented by rhEPO (750 U/kg s.c.) given 3 times weekly starting 2 weeks before TBI. Fourteen days after fractionated TBI (tumor volume of approx. 40 mm 3 ), single-dose irradiation of the tumor with varying doses was performed so that in full dose–response relationship for the probability of tumor cure was obtained. Results Radiation-i…
Lovastatin protects human endothelial cells from killing by ionizing radiation without impairing induction and repair of DNA double-strand breaks.
2006
Abstract Purpose: 3-hydroxy-3-methylglutaryl CoA reductase inhibitors (statins) are frequently used lipid-lowering drugs. Moreover, they are reported to exert pleiotropic effects on cellular stress responses, proliferation, and apoptosis. Whether statins affect the sensitivity of primary human cells to ionizing radiation (IR) is still unknown. The present study aims at answering this question. Experimental Design: The effect of lovastatin on IR-provoked cytotoxicity was analyzed in primary human umbilical vein endothelial cells (HUVEC). To this end, cell viability, proliferation, and apoptosis as well as DNA damage–related stress responses were investigated. Results: The data show that lova…
Wavelength dependence of oxidative DNA damage induced by UV and visible light.
1997
DNA damage induced by UV radiation and visible light (290-500 nm) in AS52 Chinese hamster cells was analysed by an alkaline elution assay with specific repair endonucleases. Cells were exposed to extensively filtered monochrome or broad-band radiation. Between 290 and 315 nm, the ratio of base modifications sensitive to Fpg protein (i.e. 8-hydroxyguanine and formamidopyrimidines) and T4 endonuclease V (i.e. cyclobutane pyrimidine dimers) was constant (approximately 1:200), indicating that the direct excitation of DNA is responsible for both types of damage in this range of the spectrum. While the yield of pyrimidine dimers per unit dose continued to decrease exponentially beyond 315 nm, the…
Prostate Metabolism After the Completion of Exclusive Radiation Is More Depleted After Seeds Brachytherapy Compared to External Beam Radiation Therap…
2012
International audience; Biochemical outcome after radiation therapy requires a protracted time. PSA decreases slowly over time so that it is difficult to differentiate immediately after the completion of radiation the impact of radiation in the prostate using brachytherapy or external radiotherapy. At 3 months, the mean PSA values were similar between the 2 groups: 2.54 ng/mL (±1.59) in the EBRT group and 1.88 ng/mL (±1.14) in the PPI group (p=0.23). For Choline levels, 3-months Choline / Baseline Choline ratios were 1.13 (±0.60) after EBRT vs. 0.45 (±0.23) in the PPI group (p=0.003). Similar results were observed for Citrate levels: 3-months Citrate level / Baseline Citrate level ratios we…
Fractionated External Beam Radiotherapy as a Suitable Preparative Regimen for Hepatocyte Transplantation After Partial Hepatectomy
2010
Purpose Hepatocyte transplantation is strongly considered to be a promising option to correct chronic liver failure through repopulation of the diseased organ. We already reported on extensive liver repopulation by hepatocytes transplanted into rats preconditioned with 25-Gy single dose selective external beam irradiation (IR). Herein, we tested lower radiation doses and fractionated protocols, which would be applicable in clinical use. Methods and Material Livers of dipeptidylpeptidase IV (DPPIV)-deficient rats were preconditioned with partial liver external beam single dose IR at 25 Gy, 8 Gy, or 5 Gy, or fractionated IR at 5 × 5 Gy or 5 × 2 Gy. Four days after completion of IR, a partial …
The association between extremely low-frequency electromagnetic fields and childhood leukaemia in epidemiology: enough is enough?
2010
Background: Previous pooled analyses have reported an association between magnetic fields and childhood leukaemia. We present a pooled analysis based on primary data from studies on residential magnetic fields and childhood leukaemia published after 2000. Methods: Seven studies with a total of 10 865 cases and 12 853 controls were included. The main analysis focused on 24-h magnetic field measurements or calculated fields in residences. Results: In the combined results, risk increased with increase in exposure, but the estimates were imprecise. The odds ratios for exposure categories of 0.1–0.2 μT, 0.2–0.3 μT and ⩾0.3 μT, compared with <0.1 μT, were 1.07 (95% CI 0.81–1.41), 1.16 (0.69–1.93)…
Primary optic nerve sheath meningioma
2007
BACKGROUND. Radiotherapy (RT) has occasionally been practiced in the treatment of optic nerve sheath meningioma (ONSM). Recently, stereotactic fractionated RT (SFRT) has been introduced as a tool with better precision for RT delivery. A comprehensive review was undertaken to provide more insight into this matter. METHODS. A literature search was performed to identify reports dealing with both clinical aspects (diagnosis) and treatment in ONSM, focusing on RT in primary (p)ONSM. In particular, major emphasis was placed on the role of SFRT in pONSM. RESULTS. SFRT was capable of achieving excellent local tumor control, with improved/stable functional capacity in ≥80%, accompanied with very low…
Remote Estimation of Canopy Water Content in Different Crop Types with New Hyperspectral Indices
2018
A diverse range of vegetation indices have earlier been developed for the remote estimation of canopy water content (CWC), but most of them are not universally applicable. The aim of this study is to define new indices valid for a wide variety of crop types, that allow to obtain CWC maps at a large spatial scale. These indices were developed based on PROSAIL simulations and then optimized with an experimental dataset (SPARC03; Barrax, Spain), which consists of field data including water content and other biophysical parameters collected for 6 different crops (lucerne, corn, potato, sugar beet, garlic and onion) and associated TOC reflectance spectra acquired by the HyMap airborne sensor. Sp…
Estimating chlorophyll content of crops from hyperspectral data using a normalized area over reflectance curve (NAOC)
2010
Abstract The Normalized Area Over reflectance Curve (NAOC) is proposed as a new index for remote sensing estimation of the leaf chlorophyll content of heterogeneous areas with different crops, different canopies and different types of bare soil. This index is based on the calculation of the area over the reflectance curve obtained by high spectral resolution reflectance measurements, determined, from the integral of the red–near-infrared interval, divided by the maximum reflectance in that spectral region. For this, use has been made of the experimental data of the SPARC campaigns, where in situ measurements were made of leaf chlorophyll content, LAI and fCOVER of 9 different crops – thus, …