Ionizing Radiation Research Papers - Academia.edu (original) (raw)

Nuclear medicine workers are occupationally exposed to chronic ionizing radiation. It is known that ionizing radiation may have damaging effects on chromosomes. In the present study, we investigated the genotoxic effects of ionizing... more

Nuclear medicine workers are occupationally exposed to chronic ionizing radiation. It is known that ionizing radiation may have damaging effects on chromosomes. In the present study, we investigated the genotoxic effects of ionizing radiation on nuclear medicine workers. We used two different indicators of genotoxicity methods: sister chromatid exchange (SCE) and micronucleus (MN).

Este articulo presenta una revision de los fundamentos de la tomografia computarizada, empezando por un recuento de los inicios y progresos de esta tecnica a traves del tiempo, y continuando con una descripcion de los principios fisicos... more

Este articulo presenta una revision de los fundamentos de la tomografia computarizada, empezando por un recuento de los inicios y progresos de esta tecnica a traves del tiempo, y continuando con una descripcion de los principios fisicos que rigen la produccion de los rayos X. El articulo tambien discute las bases matematicas para la reconstruccion de las imagenes a partir de proyecciones utilizando metodos analiticos o iterativos. En una seccion independiente, se revisan los conceptos mas importantes relacionados con los riesgos de la radiacion ionizante y se discuten investigaciones recientes, algunas polemicas, acerca de los beneficios y riesgos asociados con la tomografia computarizada y como estos afectan los protocolos de adquisicion de las imagenes. Finalmente, con base en los avances cientificos y tendencias mas recientes, el articulo propone las areas que, presumiblemente, continuaran siendo el centro de atencion de la tomografia computarizada de rayos X en los proximos anos.

Chest ultrasonography is a useful tool for assessing disease activity in the peripheral lung parenchyma, pleura, chest wall, diaphragm, and mediastinum. Ultrasound imaging also provides highly useful guidance in invasive diagnostic and... more

Chest ultrasonography is a useful tool for assessing disease activity in the peripheral lung parenchyma, pleura, chest wall, diaphragm, and mediastinum. Ultrasound imaging also provides highly useful guidance in invasive diagnostic and therapeutic procedures. The main advantages of this imaging technology are the absence of ionizing radiation and the possibility of real-time bedside applications. The chief indications and limitations of chest ultrasonography and the principal sonographic signs are reviewed.

Phosphors are key components of x-ray framing cameras. On implosion experiments at the National Ignition Facility, the x-ray framing cameras must operate in a harsh neutron induced ionizing radiation. One promising approach of neutron... more

Phosphors are key components of x-ray framing cameras. On implosion experiments at the National Ignition Facility, the x-ray framing cameras must operate in a harsh neutron induced ionizing radiation. One promising approach of neutron induced background reduction is separation of the neutron background with using difference of x-ray and neutron time-of-flight. To complete x-ray imaging before arrival of the neutron induced radiation to the detector, it is crucial to find a phosphor which has high efficiency and fast decay time. We tested various phosphor materials to optimize design of framing cameras for implosion experiments.

Allelic loss is an important mutational mechanism in human carcinogenesis. Loss of heterozygosity (LOH) at an autosomal locus is one outcome of the repair of DNA double-strand breaks (DSBs) and can occur by deletion or by mitotic... more

Allelic loss is an important mutational mechanism in human carcinogenesis. Loss of heterozygosity (LOH) at an autosomal locus is one outcome of the repair of DNA double-strand breaks (DSBs) and can occur by deletion or by mitotic recombination. We report that mitotic recombination between homologous chromosomes occurred in human lymphoid cells exposed to densely ionizing radiation. We used cells derived from the same donor that express either normal TP53 (TK6 cells) or homozygous mutant TP53 (WTK1 cells) to assess the influence of TP53 on radiation-induced mutagenesis. Expression of mutant TP53 (Met 237 Ile) was associated with a small increase in mutation frequencies at the hemizygous HPRT (hypoxanthine phosphoribosyl transferase) locus, but the mutation spectra were unaffected at this locus. In contrast, WTK1 cells (mutant TP53) were 30-fold more susceptible than TK6 cells (wild-type TP53) to radiation-induced mutagenesis at the TK1 (thymidine kinase) locus. Gene dosage analysis c...

Human population throughout the world is surrounded by an invisible continuously increasing web of radiation, originating from both natural and non-natural sources. Radiation is of two types: ionizing and non-ionizing depending upon their... more

Human population throughout the world is surrounded by an invisible continuously increasing web of radiation, originating from both natural and non-natural sources. Radiation is of two types: ionizing and non-ionizing depending upon their energy. The exposure to radiation has increased many folds in the recent years with the invention and launch of many electromagnetic devices. Exposure to ionizing radiations has been found to cause severe abnormalities in human beings such as DNA damage, cancer, infertility, electro-hypersensitivity, etc. which however is of different intensity depending upon the age group of human beings, with children and fetus being the maximum sufferers because of immature immune system and also various other cells in their body are still at the stage of division and differentiation. Present study has been aimed to investigate a generalized preliminary idea of various health related complications caused by ionizing radiations to human beings with special emphasis to fetus and children.

Here we have used an intrachromosomal substrate to monitor the end joining of distant ends, which leads to DNA rearrangements in mammalian cells. We show that silencing Mre11 reduces the efficiency of nonhomologous end joining (NHEJ),... more

Here we have used an intrachromosomal substrate to monitor the end joining of distant ends, which leads to DNA rearrangements in mammalian cells. We show that silencing Mre11 reduces the efficiency of nonhomologous end joining (NHEJ), affecting both the canonical and alternative pathways, partly in a manner that is independent of the ataxia-telangiectasia mutated kinase (ATM). Silencing of Rad50 or CtIP decreases end-joining efficiency in the same pathway as Mre11. In cells defective for Xrcc4, the MRE11-RAD50-NBS1 (MRN) complex inhibitor MIRIN decreases end-joining frequencies, demonstrating a role for MRN in alternative NHEJ. Consistently, MIRIN sensitizes both complemented and NHEJ-defective cells to ionizing radiation. Conversely, overexpression of Mre11 stimulates the resection of single-stranded DNA and increases alternative end joining, through a mechanism that requires Mre11's nuclease activity, but in an ATM-independent manner. These data demonstrate that, in addition to its role in ATM activation, Mre11 can favor alternative NHEJ through its nuclease activity.

Page 1. 1484 IEEE TRANSACTIONS ON NUCLEAR SCIENCE, VOL. 40, NO. 6, DECEMBER 1993 Altitude and Latitude Variations in Avionics SEU and Atmospheric Neutron Flux E. Normand and T. J. Baker Boeing Defense & Space Group, Seattle, WA... more

Page 1. 1484 IEEE TRANSACTIONS ON NUCLEAR SCIENCE, VOL. 40, NO. 6, DECEMBER 1993 Altitude and Latitude Variations in Avionics SEU and Atmospheric Neutron Flux E. Normand and T. J. Baker Boeing Defense & Space Group, Seattle, WA 98124-2499 Abstract ...