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  • Humans
  • While LD100 is estimated around 1000 rads for humans, and 56,128 rads (64,000 roentgens) for the fruit fly Drosophila melanogaster, a study showed that H. hebetor survived X-ray radiations of 158,080 rads (180,250 R). In this study, irradiated groups even had an increased life span compared to non-irradiated control groups, an effect attributed to the lack of activity of irradiated individuals. (wikipedia.org)
  • Studying dose response, and developing dose-response models, is central to determining "safe", "hazardous" and (where relevant) beneficial levels and dosages for drugs, pollutants, foods, and other substances to which humans or other organisms are exposed. (wikipedia.org)
  • While the effects of high and acute doses of ionising radiation are easily observed and understood in humans (e.g. (wikipedia.org)
  • However, they cautioned that it is not yet known if radiation hormesis occurs outside the laboratory, or in humans. (wikipedia.org)
  • Reports by the United States National Research Council and the National Council on Radiation Protection and Measurements and the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) argue that there is no evidence for hormesis in humans and in the case of the National Research Council hormesis is outright rejected as a possibility. (wikipedia.org)
  • organisms
  • The median infective dose (ID50) is the number of organisms received by a person or test animal qualified by the route of administration (e.g., 1,200 org/man per oral). (wikipedia.org)
  • Because of the difficulties in counting actual organisms in a dose, infective doses may be expressed in terms of biological assay, such as the number of LD50's to some test animal. (wikipedia.org)
  • In toxicology it is specifically the highest tested dose or concentration of a substance (i.e. a drug or chemical) or agent (e.g. radiation), at which no such adverse effect is found in exposed test organisms where higher doses or concentrations resulted in an adverse effect. (wikipedia.org)
  • dosage
  • Wing has quarreled with an assumption regarding the dosage of radiation the populate sustained. (albionmonitor.com)
  • The former means dosage or amount of dose administered to a person, whereas the latter means the time-dependent concentration (often in the circulatory blood or plasma) or concentration-derived parameters such as AUC (area under the concentration curve) and Cmax (peak level of the concentration curve) of the drug after its administration. (wikipedia.org)
  • In biological warfare infective dosage is the number of infective doses per minute for a cubic meter (e.g. (wikipedia.org)
  • 1000
  • 1000 times background (average 47.7 mSv, maximum 2360 mSv excess cumulative dose) - it was not until 1992 that the radioactive contamination was discovered. (wikipedia.org)
  • Gamma Rays
  • The goal of this research is to establish a more mechanistic approach to estimating risk and to answer questions, including whether HZE effects can be scaled from those of gamma rays, whether risk is linear with low dose-rate, and how individual radiation sensitivity impacts the risks for astronauts, a population that is selected for many factors related to excellence in health. (wikipedia.org)
  • toxins
  • Environmental factors, including toxins, radiation, and ultraviolet light, have cumulative effects, which are worsened by the loss of protective and restorative mechanisms due to alterations in gene expression and chemical processes within the eye. (wikipedia.org)
  • It is conjectured that low doses of toxins or other stressors might activate the repair mechanisms of the body. (wikipedia.org)
  • pneumonitis
  • Despite recent technological advances in radiation therapy (RT) such as three-dimensional (3D) conformal RT and intensity-modulated RT and even 4D RT (although 4DRT is not being practiced in most of the centres in our country), radiation pneumonitis (RP) remains an important dose-limiting toxicity in thoracic RT [ 2 ]. (omicsonline.org)
  • risks
  • The assessment of carcinogenic risks associated with doses of ionizing radiation from 0.2 Sv to 5 Sv is based on numerous epidemiological data. (blogspot.com)
  • Epidemiological studies have been carried out to determine the possible carcinogenic risk of doses lower than 100 mSv, and they have not been able to detect statistically significant risks even on large cohorts or populations. (blogspot.com)
  • It is highly unlikely that putative carcinogenic risks could be estimated or even established for such doses through case-control studies or the follow-up of cohorts. (blogspot.com)
  • Because of these epidemiological limitations, the only method for estimating the possible risks of low doses ( (blogspot.com)
  • Estimating risks of radiotherapy complications as part of informed consent: the high degree of variability between radiation oncologists may be related to experience. (biomedsearch.com)
  • METHODS AND MATERIALS: A survey was mailed to Australian radiation oncologists, who were asked to estimate risks of RT complications given 49 clinical scenarios. (biomedsearch.com)
  • A TMI Public Health Fund then was established to fund research into radiation heath effects and radiation protection, hiring investigators from Columbia University to see if "risks from specified cancers may have been raised by exposure to radiation emanating from the Three Mile Island Nuclear power plant. (albionmonitor.com)
  • The International Commission on Radiological Protection maintains a model of these risks as a function of absorbed dose and other factors. (wikipedia.org)
  • toxicology
  • In toxicology, the lethal dose (LD) is an indication of the lethal toxicity of a given substance or type of radiation. (wikipedia.org)
  • In toxicology, hormesis is a dose response phenomenon characterized by a low dose stimulation, high dose inhibition, resulting in either a J-shaped or an inverted U-shaped dose response. (wikipedia.org)
  • In 2010, a paper published in the journal Environmental Toxicology & Chemistry showed that low doses of methylmercury, a potent neurotoxic pollutant, improved the hatching rate of mallard eggs. (wikipedia.org)
  • damage
  • Recent works suggest that there is a threshold of damage under which low doses and dose rates do not activate intracellular signalling and repair systems, a situation leading to cell death. (blogspot.com)
  • Biophysical models have shown that the energy deposition events by high-LET radiation produce differential DNA lesions, including complex DNA breaks, and that there are qualitative differences between high- and low-LET radiation, in both the induction and the repair of DNA damage. (wikipedia.org)
  • Complex damage is uncommon for endogenous damage or low-LET radiation, and has been associated with the increased RBE of densely ionizing radiation. (wikipedia.org)
  • However, the quality of chromosome damage is different when heavy ions are compared to sparsely ionizing radiation. (wikipedia.org)
  • mutations
  • the probable mechanism is radiation-induction of mutations in the coronary arteries, resulting in dysfunctional clones (mini-tumors) of smooth muscle cells. (ratical.org)
  • tissue
  • the consequences of the difference on the dose-effect relations for normal tissue injury were studied by comparing different NTCP model/parameters extracted from a review of published studies. (nih.gov)
  • The material absorbing the radiation can be human tissue or silicon microchips or any other medium (for example, air, water, lead shielding, etc. (wikipedia.org)
  • The Röntgen equivalent physical (rep), introduced by Herbert Parker in 1945, was the absorbed energetic dose to tissue before factoring in relative biological effectiveness. (wikipedia.org)
  • This limitation is caused by the complexity of biological systems and the often unknown biological processes operating between the external exposure and the adverse cellular or tissue response. (wikipedia.org)
  • Studies with protons and HZE nuclei of relative biological effectiveness for molecular, cellular, and tissue endpoints, including tumor induction, demonstrate risk from space radiation exposure. (wikipedia.org)
  • Radiography
  • In March-August 1962, a radiation incident in Mexico City occurred when a ten-year-old boy took home an unprotected industrial radiography source. (wikipedia.org)
  • Four people died from overexposure to radiation from a 5-Ci cobalt-60 capsule, an industrial radiography orphaned source that was not contained in its proper shielding. (wikipedia.org)
  • genes
  • Modern transcriptional analysis of cellular genes using microarray technology reveals that many genes are activated following doses much lower than those for which mutagenesis is observed. (blogspot.com)
  • These methods have been a source of considerable progress by showing that depending on the dose and the dose rate not the same genes are transcribed. (blogspot.com)
  • Statistical analysis identified modulated genes at each of the individual doses. (nih.gov)
  • Twenty-nine genes were common to all doses with expression levels ranging from 2-10 fold relative to control treatment group. (nih.gov)
  • Box-plots of the responding genes from the WBC qPCR dataset allowed for a visual comparison of the two radiation types and the range in inter-individual variability between transcripts (Figure 5). (nih.gov)
  • Furthermore, the majority of genes displayed dose-response trends for both α-particle and X-ray radiation. (nih.gov)
  • lethal
  • The linear quadratic model is now most often used to describe the cell survival curve, assuming that there are two mechanisms to cell death by radiation: A single lethal event or an accumulation of harmful but non-lethal events. (wikipedia.org)
  • Whereas single lethal events lead to an exponent that is linearly related to dose, the survival fraction function for a two-stage mechanism carries an exponent proportional to the square of dose. (wikipedia.org)
  • Because resistance varies from one individual to another, the "lethal dose" represents a dose (usually recorded as dose per kilogram of subject body weight) at which a given percentage of subjects will die. (wikipedia.org)
  • The lethal concentration is a lethal dose measurement used for gases or particulates. (wikipedia.org)
  • The median lethal dose, LD50 (abbreviation for "lethal dose, 50%"), LC50 (lethal concentration, 50%) or LCt50 (lethal concentration and time) of a toxin, radiation, or pathogen is the dose required to kill half the members of a tested population after a specified test duration. (wikipedia.org)
  • LD50 i.v." The related quantities LD50/30 or LD50/60 are used to refer to a dose that without treatment will be lethal to 50% of the population within (respectively) 30 or 60 days. (wikipedia.org)
  • The lowest lethal dose (LDLo) is the least amount of drug that can produce death in a given animal species under controlled conditions. (wikipedia.org)
  • 1953
  • It was originally defined in CGS units in 1953 as the dose causing 100 ergs of energy to be absorbed by one gram of matter. (wikipedia.org)
  • In 1953 the ICRU recommended the rad, equal to 100 erg/g as a new unit of absorbed radiation, but then promoted a switch to the gray in the 1970s. (wikipedia.org)
  • duration
  • It either does not provide the effects of drug with respect to duration and dose, or it does not address the interpretation of risk based on toxicologically relevant effects. (wikipedia.org)
  • Curves
  • Statistical analysis of dose-response curves may be performed by regression methods such as the probit model or logit model, or other methods such as the Spearman-Karber method. (wikipedia.org)
  • Dose-response curves are generally sigmoidal and monophasic and can be fit to a classical Hill equation. (wikipedia.org)
  • lung
  • However, children are particularly sensitive to radioactivity, with childhood leukemias and other cancers increasing even within natural and man-made background radiation levels (under 4 mSv cumulative with 1 mSv being an average annual dose from terrestrial and cosmic radiation excluding radon which primarily doses the lung). (wikipedia.org)
  • threshold
  • A linear no-threshold relationship (LNT) describes well the relation between the dose and the carcinogenic effect in this dose range where it could be tested. (blogspot.com)
  • Biologically based models using dose are preferred over the use of log(dose) because the latter can visually imply a threshold dose when in fact there is none. (wikipedia.org)
  • The first point along the graph where a response above zero (or above the control response) is reached is usually referred to as a threshold-dose. (wikipedia.org)
  • For most beneficial or recreational drugs, the desired effects are found at doses slightly greater than the threshold dose. (wikipedia.org)
  • Therefore, estimating Linear no-threshold model (LNT) continues to be the model generally used by regulatory agencies for human radiation exposure. (wikipedia.org)
  • chemotherapy
  • Recent interim analysis of the HD11 trial of the GHSG: intensification of chemotherapy and reduction of radiation dose in early unfavorable stage Hodgkin's lymphoma. (springer.com)
  • Ten-year results of a German Hodgkin Study Group randomized trial of standard and increased dose BEACOPP chemotherapy for advanced Hodgkin lymphoma (HD9). (springer.com)
  • Standard and increased-dose BEACOPP chemotherapy compared with COPP-ABVD for advanced Hodgkin's disease. (springer.com)
  • Dose escalation of BEACOPP chemotherapy for advanced Hodgkin's disease in the HD9 trial of the German Hodgkin's Lymphoma Study Group (GHSG). (springer.com)
  • Further chemotherapy versus low-dose involved-field radiotherapy as consolidation of complete remission after six cycles of alternating chemotherapy in patients with advance Hodgkin's disease. (springer.com)
  • irradiation
  • Only comparisons between geographical regions with high and low natural irradiation and with similar living conditions could provide valuable information for this range of doses and dose rates. (blogspot.com)
  • hormesis
  • Hormesis is any process in a cell or organism that exhibits a biphasic response to exposure to increasing amounts of a substance or condition. (wikipedia.org)
  • A pollutant or toxin showing hormesis thus has the opposite effect in small doses as in large doses. (wikipedia.org)
  • The hormesis model of dose response is vigorously debated. (wikipedia.org)
  • Radiation hormesis is the hypothesis that low doses of ionizing radiation (within the region of and just above natural background levels) are beneficial, stimulating the activation of repair mechanisms that protect against disease, that are not activated in absence of ionizing radiation. (wikipedia.org)
  • The reserve repair mechanisms are hypothesized to be sufficiently effective when stimulated as to not only cancel the detrimental effects of ionizing radiation but also inhibit disease not related to radiation exposure (see hormesis). (wikipedia.org)
  • Government and regulatory bodies disagree on the existence of radiation hormesis and research points to the "severe problems and limitations" with the use of hormesis in general as the "principal dose-response default assumption in a risk assessment process charged with ensuring public health protection. (wikipedia.org)
  • Quoting results from a literature database research, the Académie des Sciences - Académie nationale de Médecine (French Academy of Sciences - National Academy of Medicine) stated in their 2005 report concerning the effects of low-level radiation that many laboratory studies have observed radiation hormesis. (wikipedia.org)
  • small
  • Many earlier researchers, as well as government and industry officials, accept as fact that only small amounts of radiation were released into the atmosphere, Wing said. (albionmonitor.com)
  • Prolongation of life of Tribolium confusum apparently due to small doses of X-rays. (wikipedia.org)
  • German pharmacologist Hugo Schulz first described such a phenomenon in 1888 following his own observations that the growth of yeast could be stimulated by small doses of poisons. (wikipedia.org)
  • cells
  • Identification of gene-based responses in human blood cells exposed to alpha particle radiation. (nih.gov)
  • Peripheral blood mononuclear cells (PBMCs) were used to identify sensitive and robust gene-based biomarkers of α-particle radiation exposure. (nih.gov)
  • Cells were isolated from healthy individuals and were irradiated at doses ranging from 0-1.5 Gy. (nih.gov)
  • Dataset is obtained from qPCR results in isolated white blood cells exposed to α-particle and X-ray radiation. (nih.gov)
  • It depicts the relationship between the fraction of cells retaining their reproductive integrity and the absorbed dose of radiation. (wikipedia.org)
  • Such phytochemicals trigger hormetic responses in brain cells which can improve brain function and may increase the resistance of neurons to injury and age-related neurodegenerative disorders such as Alzheimer's disease and Parkinson's disease. (wikipedia.org)
  • commonly
  • In the 1930s the roentgen was the most commonly used unit of radiation exposure. (wikipedia.org)
  • A commonly used dose-response curve is the EC50 curve, the half maximal effective concentration, where the EC50 point is defined as the inflection point of the curve. (wikipedia.org)
  • These measures are used more commonly with radiation, as survival beyond 60 days usually results in recovery. (wikipedia.org)
  • Cataracts are most commonly due to aging but may also occur due to trauma or radiation exposure, be present from birth, or occur following eye surgery for other problems. (wikipedia.org)
  • adverse
  • Relation between benchmark dose and no-observed-adverse-effect level in clinical research: Effects of daily alcohol intake on blood pressure in Japanese salesmen" (Submitted manuscript). (wikipedia.org)
  • nuclear
  • Also debunking false claims about radiation, and nuclear power. (blogspot.com)
  • The Committee for Nuclear Responsibility, Inc. (CNR) is a non-profit educational group organized in 1971 to provide independent analyses of the health effects and sources of ionizing radiation. (ratical.org)
  • Radiation-hardened components designed for military or nuclear applications can survive up to 100 Mrad (1 MGy). (wikipedia.org)
  • These radioactive particles are by-products generated as a result of activities related to nuclear energy and constitute a pollution and a radiotoxicity problem (with serious health and ecological consequences) due to its unstable nature of ionizing radiation emissions. (wikipedia.org)
  • Hodgkin's
  • Eight cycles of escalated-dose BEACOPP compared with four cycles of escalated-dose BEACOPP followed by four cycles of baseline-dose BEACOPP with or without radiotherapy in patients with advanced-stage Hodgkin's lymphoma: final analysis of the HD12 trial of the German Hodgkin Study Group. (springer.com)
  • microarray
  • A comparison of the differential gene responses obtained from the qPCR of WBCs and microarray analysis of PBMCs showed similar fold change and statistical significance for the majority of the 68 transcripts that were assessed (Table 5). (nih.gov)