Search results for "ionizing"

Ionizing radiation but not anticancer drugs causes cell cycle arrest and failure to activate the mitochondrial death pathway in MCF-7 breast carcinom…

2001

There is considerable evidence that ionizing radiation (IR) and chemotherapeutic drugs mediate apoptosis through the intrinsic death pathway via the release of mitochondrial cytochrome c and activation of caspases -9 and -3. Here we show that MCF-7 cells that lack caspase-3 undergo a caspase-dependent apoptotic cell death in the absence of DNA fragmentation and alpha-fodrin cleavage following treatment with etoposide or doxorubicin, but not after exposure to IR. Re-expression of caspase-3 restored DNA fragmentation and alpha-fodrin cleavage following drug treatment, but it did not alter the radiation-resistant phenotype of these cells. In contrast to the anticancer drugs, IR failed to induc…

Zur Pharmakologie ionisierender Strahlen

1954

Unter Verwendung des Mause-Ascitestumors wurden eine Reihe von Veranderungen der hormonalen Situation des Wirtstieres auf das Tumorwachstum untersucht: Exstirpation von innersekretorischen Drusen, Rontgenbestrahlung, Ultraviolettbestrahlung, Kalte, Zufuhr verschiedener Hormone. Alle diese Eingriffe hatten keinen Einflus auf das Tumorwachstum. In gleicher Weise wurde mit 2000 r in vivo bestrahlter Ascitestumor verwendet. Hierbei ergab eine Vorbestrahlung des Thymus der Empfangertiere eine Steigerung der Lebenserwartung gegenuber den unbehandelten Kontrolltieren.

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…

PROPERTIES OF IONIZING RADIATION CURED POLYMER MATRICES FOR CARBON FIBER COMPOSITES AFTER AGEING DUE TO MOISTURE ABSORPTION AND THERMAL TREATMENT

2008

Vibrational effects in Na2( , v′)+Na(3p3/2) associative ionization

1999

Abstract Associative ionizing Na2( A 1 Σ + u , v′)+Na(3p3/2) collisions have been studied in a single supersonic beam with respect to the influence of the initial vibrational excitation of the molecules on the reaction efficiency. An enhancement of trimer ion yield of nearly one order of magnitude has been observed as the vibrational excitation increases from v′=0 to v′=14.

Nitric Oxide Is a Promising Enhancer for Cancer Therapy

2010

This report summarizes the present state of our knowledge pertaining to the nitric oxide (NO)-induced sensitization of tumor cell death. The effects of NO and its synergy with ionizing radiations, with members of the TNF family, and with chemotherapy have been investigated. The effect of NO-induced sensitization and the underlying molecular mechanisms are discussed.

Micronucleus frequencies and clonogenic cell survival in TK6 cells exposed to changing dose rates under controlled temperature conditions.

2014

In most exposure scenarios the dose rate of exposure is not constant. Despite this, very little information exists on the possible biological effects of exposing cells to radiation under the conditions of a changing dose rate. The current study highlights interesting effects following exposure under these conditions.We constructed a new exposure facility that allows exposing cells inside an incubator and used it to irradiate human lymphoblastoid TK6 cells both after a moderate (0.48 Gy) and a high (1.1 Gy) dose, where the change in dose rate was, respectively, ≈ 17-fold (2.2-37 mGy/min) and ≈ 39-fold (2.7-106 mGy/min). Clonogenic survival and micronuclei (MN) induction were the chosen endpo…

2019

From the very beginnings of radiotherapy, a crucial question persists with how to target the radiation effectiveness into the tumor while preserving surrounding tissues as undamaged as possible. One promising approach is to selectively pre-sensitize tumor cells by metallic nanoparticles. However, though the “physics” behind nanoparticle-mediated radio-interaction has been well elaborated, practical applications in medicine remain challenging and often disappointing because of limited knowledge on biological mechanisms leading to cell damage enhancement and eventually cell death. In the present study, we analyzed the influence of different nanoparticle materials (platinum (Pt), and gold (Au)…

DNA damage-induced cell death: From specific DNA lesions to the DNA damage response and apoptosis

2011

DNA damaging agents are potent inducers of cell death triggered by apoptosis. Since these agents induce a plethora of different DNA lesions, it is firstly important to identify the specific lesions responsible for initiating apoptosis before the apoptotic executing pathways can be elucidated. Here, we describe specific DNA lesions that have been identified as apoptosis triggers, their repair and the signaling provoked by them. We discuss methylating agents such as temozolomide, ionizing radiation and cisplatin, all of them are important in cancer therapy. We show that the potentially lethal events for the cell are O(6)-methylguanine adducts that are converted by mismatch repair into DNA dou…

Determination of New Radical Species in Ammonium Tartrate Dosimeters by CW- and Pulsed-EPR Techniques

2015

Samples of ammonium tartrate irradiated with doses of about 0.1–1 kGy by different beams of ionizing radiation (60Co–γ, 19 MeV protons and 62 MeV per nucleon carbon ions) were studied by continuous-wave electron paramagnetic resonance (cw-EPR) and by pulse-EPR techniques. Careful analysis of the cw-EPR and of the echo-detected EPR spectra allowed the identification of a second radical in the system besides the already known radical formed at high temperature by an hydrogen elimination at C(2) position [M. Brustolon et al., Res. Chem. Int 4:359, 1996]. The spectrum of the radical is compatible with that of a radical obtained by hydroxyl elimination.