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Sample records for cellular radiobiological action

  1. Stochastic, weighted hit size theory of cellular radiobiological action

    International Nuclear Information System (INIS)

    Bond, V.P.; Varma, M.N.

    1982-01-01

    A stochastic theory that appears to account well for the observed responses of cell populations exposed in radiation fields of different qualities and for different durations of exposure is described. The theory appears to explain well most cellular radiobiological phenomena observed in at least autonomous cell systems, argues for the use of fluence rate (phi) instead of absorbed dose for quantification of the amount of radiation involved in low level radiation exposure. With or without invoking the cell sensitivity function, the conceptual improvement would be substantial. The approach suggested also shows that the absorbed dose-cell response functions currently employed do not reflect the spectrum of cell sensitivities to increasing cell doses of a single agent, nor can RBE represent the potency ratio for different agents that can produce similar quantal responses. Thus, for accurate comparison of cell sensitivities among different cells in the same individual, or between the cells in different kinds of individuals, it is necessary to quantify cell sensitivity in terms of the hit size weighting or cell sensitivity function introduced here. Similarly, this function should be employed to evaluate the relative potency of radiation and other radiomimetic chemical or physical agents

  2. History of radiobiology in Argentina

    International Nuclear Information System (INIS)

    Mayo, Jose

    2004-01-01

    Radiobiology is a multidisciplinary science dealing with ionising radiation effects on biological material. The history of Radiobiology begins in Germany and France around 1886. Radiobiology was introduced in Argentina in 1926 at the Institute of Oncology Angel H. Roffo as a biomedical research branch. Later on in 1957 was incorporated at the National Atomic Energy Commission (CNEA) of Argentina as a result of the newly started nuclear activities in Argentina. Prior that time no Radiobiology research existed in Argentina. To fill this need a Project to create new laboratories was elaborated by the CNEA. New laboratories in Radiobiodosimetry, Cellular Radiobiology, Radiopathology, Radiomicrobiology, Genetics and Somatic Effects were created. Human resources on different areas of Radiobiology were formed with the assistance of IAEA. With professional and technical personnel specialized in Radiobiology at the beginning of the 1970 decade, the transference of fundamental and applied research to others laboratories started. (author)

  3. Basic Radiobiology. Chapter 2

    Energy Technology Data Exchange (ETDEWEB)

    Dale, R. G. [Department of Surgery and Cancer, Faculty of Medicine, Imperial College London, London (United Kingdom); Wondergem, J. [Division of Human Health, International Atomic Energy Agency, Vienna (Austria)

    2014-12-15

    Radiobiology is the study (both qualitative and quantitative) of the actions of ionizing radiations on living matter. Since radiation has the ability to cause changes in cells which may later cause them to become malignant, or bring about other detrimental functional changes in irradiated tissues and organs, consideration of the associated radiobiology is important in all diagnostic applications of radiation. Additionally, since radiation can lead directly to cell death, consideration of the radiobiological aspects of cell killing is essential in all types of radiation therapy.

  4. DOE/CEC [Department of Energy/Commission of the European Communities] workshop on critical evaluation of radiobiological data to biophysical modeling

    International Nuclear Information System (INIS)

    1988-01-01

    The Department of Energy's Office of Health and Environmental Research and the Commission of the European Communities (CEC) Radiation Protection Program support the majority of Research in the Field of Radiobiological Modeling. This field of science develops models based on scientifically sound principles to predict biological response (at the cellular, molecular, and animal level) to exposure to low level ionizing radiation. Biophysical models are an important tool for estimating response of ionizing radiation at low doses and dose rates. Generally speaking, the biophysical models can be classified into two groups: (1) mechanistic models and (2) phenomenological models. Mechanistic models are based on some assumptions about the physical, chemical, or biological mechanisms of action in association with radiobiological data whereas the phenomenological models are based solely on available experimental data on radiobiological effects with less emphasis on mechanisms of action. There are a number of these models which are being developed. Since model builders rely on radiobiological data available in the literature either to develop mechanistic or phenomenological models, it is essential that a critical evaluation of existing radiobiological data be made and data that is generally considered good and most appropriate for biophysical modeling be identified. A Workshop jointly sponsored by the DOE and the CEC was held at Oak Ridge, Tennessee from June 23--25, 1988, to review the data available from physical and chemical, cellular and molecular and animal studies with ionizing radiation

  5. Biophysics of radiation action

    International Nuclear Information System (INIS)

    Dertinger, H.

    1984-01-01

    Understanding the cellular response to ionizing radiation is not only necessary to meet the requirements of radioprotection, but also for medical application of radiation in cancer treatment. In terms of radiobiology, cancer therapy means the selective inactivation of malignant cells without affecting the normal healthy tissue. However, for several physical and biological reasons, this ideal situation is normally not attained. The elaboration of biophysical parameters that could be used to improve the selective sterilization of tumor cells has become one of the main activities of cellular radiobiology during the last two decades. Progress in this field has been facilitated by the development of tissue culture techniques allowing to grow and analyze cells in a synthetic nutrient medium. This chapter describes the physical and biological factors which determine cellular radiosensitivity and which are important to know for better understanding the cellular radiation action, in particular with reference to cancer treatment

  6. Biophysical models of radiobiological effects

    International Nuclear Information System (INIS)

    Obaturov, G.M.

    1987-01-01

    Radiobiological effect models at different organization levels, developed by the author, are presented. Classification and analysis of concepts and biophysical models at molecular, genetic and cellular levels, developed by Soviet and foreign authors in comparison to inherent models, are conducted from the viewpoint of system approach to radiobiological processes and of modelling principles. Models are compared with each other, limits of their applicability and drawbacks are determined. Evaluation of the model truthfulness is conducted according to a number of criteria, ways of further investigations and experimental examination of some models are proposed

  7. Paradigms of modern radio-biology

    International Nuclear Information System (INIS)

    Grodzins'kij, D.M.

    2005-01-01

    The basic paradigms of modern radio-biology are considered as models of pictures of essence of radio-biology problems and methods of their decision. It is marked on absolute heuristics of these ascending conceptual assertions and their assistance to subsequent development of experimental science. That has the concrete display in the decision of actual tasks of protection of people from action of ionizing radiation

  8. Radiobiological Research in JINR

    CERN Document Server

    Krasavin, E A

    2000-01-01

    The results of long-term radiobiological and radiation-genetical research in DRRR (Division of Radiobiology) are summarized. The different radiation-induced effects in bacteria, yeasts, mammalian and human cells after irradiation by gamma-rays and heavy charged particles are considered. The important role of DNA repair processes in biological effectiveness of different types of radiation were shown. The data on mutagenic action of such kinds of radiation on pro- and eukaryotic cells were analyzed. On the basis of our data the hypersensitivity of human and mammalian chromosomes after low doses of gamma-rays (10-20 sGy) was revealed. The radiobiological effect of ^{211}At - methylene blue complex on human melanoma cells was studied. The extremely high effectiveness of this complex on melanoma cells was shown.

  9. An irradiation facility with a horizontal beam for radiobiological studies

    International Nuclear Information System (INIS)

    Czub, J.; Banas, D.; Braziewicz, J.; Choinski, J.; Jaskola, M.; Korman, A.; Szeflinski, Z.; Wojcik, A.

    2006-01-01

    A facility with a horizontal beam for radiobiological experiments with heavy ions has been designed and constructed at the Heavy Ion Laboratory in Warsaw Univ.. The facility is optimal to investigate the radiobiological effects of charged heavy particles on a cellular or molecular level as in the region of the Bragg peak. (authors)

  10. Experimental radiotherapy and clinical radiobiology. Vol. 20. Proceedings

    International Nuclear Information System (INIS)

    Baumann, Michael; Dahm-Daphi, Jochen; Dikomey, Ekkehard; Petersen, Cordula; Rodemannn, Hans-Peter; Zips, Daniel

    2011-01-01

    The proceedings include contributions on the following issues: laser driven proton accelerators on the way for radiotherapy, radiobiological evaluation of new radiations; molecular factors of radiation response; biological targeting; EGFR epidermal growth factor receptor/targeting - combined internal and external irradiation, radiobiology of normal tissues; dose-volume histograms for the radiotherapy: curves without radiobiological relevance or important information for the therapy planning; HPV (human papilloma virus) and radiation sensitivity of HNSCC (head and neck squamous cell carcinomas): evidence, radiobiological mechanism, clinical consequences and perspectives; mechanisms of action and intertumoral heterogeneity of response to EGFR inhibition in radiotherapy of solid tumors; evaluation of biomarkers for radiotherapy.

  11. Study of quality effects on radiobiological actions, 1

    International Nuclear Information System (INIS)

    Iwanami, Shigeru; Nakazawa, Keiji; Matsubayashi, Takashi; Hashimoto, Shozo.

    1979-01-01

    In order to interpret the quality effects of high LET radiation on the radiobiological actions, the target theory formulated by Oda on basis of the microdose concept introduced by Rossi has been developed to express intertrack effect (cumulative effect) and intratrack effect (non-cumulative effect) separately. Analysis for the dose-survival relation by this theory have been discussed with comparison of those of Rossi or Bender. If the target for the intertrack effect was the same one for the intratrack effect, it was found in this theory that the contribution of the intertrack effect for the cell lethality was larger than that of the intratrack effect in the case of high LET radiation as well as in that of low LET ones. The survival rates of Escherichia coli B/r and B sub(s-1) irradiated with heavy ions such as He, C, N and O at 4 MeV/a.m.u. and neutrons at 1, 2 and 5 MeV were calculated with this theory. The results were in reasonable agreement with experimental ones. (author)

  12. Radiobiology: radiotherapy and radiation protection, fundamental bases

    International Nuclear Information System (INIS)

    Tubiana, M.

    2008-01-01

    The radiobiology constitutes one of the most successful tools of the research in biology. It has for twenty years, as all the biology, strangely progressed with the increase of the knowledge in molecular biology and the new techniques of the genome exploration. It allows to dissect the living matter, to analyze the repair mechanisms of the damage in the molecular, cellular and tissular scale, to understand the transformation of a normal cell in cancer cell as well as the system of defence, multiple and powerful, against the carcinogenesis to mammals, notably to man. The radiobiology is the base on which the radiotherapy was built and perfected, now this one contributes largely to the cure of half of the cancers. With the increase of the number of the long-term cures, the indication of the second cancers provoked by the ionizing radiations and the cytotoxic largely increased: to reduce their frequency is an imperative, the radiobiology has to help to make it. (N.C.)

  13. CRC handbook of radiobiology

    International Nuclear Information System (INIS)

    Prasad, K.N.

    1984-01-01

    The author presents Development of Radiobiology. A Review. Basic Cell Biology. Physics of Radiation Biology. Cellular Radiation Damage. Modifications of Cellular Radiation Damage. Repair of Radiation Damage. Molecular Radiation Biology. Radiation Syndromes and their Modifications. Radiation Damage of Skin and Mucous Membrane. Radiation Damage of Nervous Tissue. Radiation Damage of Reproductive Organs. Radiation Damage of Other Organ Systems. Radiation Immunology. Background, Medical and Commercial Sources. Radiation Injuries to Human Fetuses. Radiation-Induced Genetic Damage. Radiation Carcinogenesis: Tissue Culture Model. Radiation Carcinogenesis: Animal Model. Radiation Carcinogenesis: Human Model. Radiation Carcinogenesis: Secondary Neoplasms. After Therapy of Tumors. Other Late Effects: Aging, Cataract, Aplastic Anemia. Maximum Permissible Dose (MPD). Radiation Response of Human Tumor. Radioisotopes in Biology and Medicine

  14. Oxygen as a product of water radiolysis in high-LET tracks. II. Radiobiological implications

    International Nuclear Information System (INIS)

    Baverstock, K.F.; Burns, W.G.

    1981-01-01

    Consideration is given to the possibility that molecular oxygen generated in the tracks of energetic heavy ions is responsible for the reduction in oxygen enhancement ratio (OER) with increasing linear energy transfer (LET) observed for the loss of reproductive capacity caused by radiation in many cellular organisms. Yields of oxygen relationship of OER to LET for two organisms, Chlamydomonas reinhardii and Shigella flexneri, using a simple diffusion kinetic model for radiobiological action which takes account of the diffusion of oxygen after its formation. The results of these calculations show that the model accounts well for the shape of the OER vs. LET relationship

  15. Introduction to radiobiology of targeted radionuclide therapy

    Directory of Open Access Journals (Sweden)

    Jean-Pierre ePOUGET

    2015-03-01

    Full Text Available During the last decades, new radionuclide-based targeted therapies have emerged as efficient tools for cancer treatment. Targeted radionuclide therapies (TRT are based on a multidisciplinary approach that involves the cooperation of specialists in several research fields. Among them, radiobiologists investigate the biological effects of ionizing radiation, specifically the molecular and cellular mechanisms involved in the radiation response. Most of the knowledge about radiation effects concerns external beam radiation therapy (EBRT and radiobiology has then strongly contributed to the development of this therapeutic approach. Similarly, radiobiology and dosimetry are also assumed to be ways for improving TRT, in particular in the therapy of solid tumors which are radioresistant. However, extrapolation of EBRT radiobiology to TRT is not straightforward. Indeed, the specific physical characteristics of TRT (heterogeneous and mixed irradiation, protracted exposure and low absorbed dose rate differ from those of conventional EBRT (homogeneous irradiation, short exposure and high absorbed dose rate, and consequently the response of irradiated tissues might be different. Therefore, specific TRT radiobiology needs to be explored. Determining dose-effect correlation is also a prerequisite for rigorous preclinical radiobiology studies because dosimetry provides the necessary referential to all TRT situations. It is required too for developing patient-tailored TRT in the clinic in order to estimate the best dose for tumor control, while protecting the healthy tissues, thereby improving therapeutic efficacy. Finally, it will allow to determine the relative contribution of targeted effects (assumed to be dose-related and non-targeted effects (assumed to be non-dose-related of ionizing radiation. However, conversely to EBRT where it is routinely used, dosimetry is still challenging in TRT. Therefore, it constitutes with radiobiology, one of the main

  16. The ATM gene and the radiobiology of ataxia-telangiectasia

    International Nuclear Information System (INIS)

    Jorgensen, T.J.; Shiloh, Y.

    1996-01-01

    Ataxia-telangiectasia (A-T) is the classic human genetic disease involving severe ionizing radiation sensitivity and as such has been intensely studied by radiation biologists over the years. Unlike its counterpart for UV light sensitivity -xeroderma pigmentosum - A-T has no obvious DNA repair defect; and there has been much speculation as to the mechanism underlying the altered radioresponses associated with this disease. The gene defective in A-T (ATM) has recently been cloned, and its primary coding sequence determined. The primary sequence of the ATM protein suggests that it has some regulatory functions related to cellular radioresponse and maintenance of genomic stability, and shares these functions with a growing family of other proteins in various organisms. At this juncture it is appropriate to review our current knowledge about the radiobiology of A-T and reflect on the possible radiobiological mechanisms that are suggested by the ATM gene itself. This article will attempt briefly to review current knowledge about the radiobiology of A-T and to introduce new speculations about underlying radiobiological mechanisms that are suggested by the primary amino acid sequence of the predicted ATM gene product. (Author)

  17. Radiobiology

    International Nuclear Information System (INIS)

    Kuruc, J.

    2009-01-01

    This text-book (electronic book - multi-media CD-ROM) constitutes a course-book - author's collection of lectures. It consists of 13 lectures in which the reader acquaints with the basis of radiobiology: Introduction to radiobiology; Physical fundamentals of radiobiology; Radiation of cells; Modification of radiation damage of cells; Reparation of radiation damage of cells; Radiation syndromes and their modification; Radiation injury; Radiation damage of tissues; Effect of radiation on embryo and fetus; Biological effects of incorporated radionuclides; Therapy of acute irradiation sickness; Delayed consequences of irradiation; Radiation oncology and radiotherapy. This course-book may be interesting for students, post-graduate students of chemistry, biology, physics, medicine as well as for teachers, scientific workers and physicians. (author)

  18. Applied radiobiology

    International Nuclear Information System (INIS)

    Sutton, M.L.; Hendry, J.H.

    1985-01-01

    The experience of courses in radiobiology suggests a very widespread failure to relate the phenomena of ''classical'' radiobiology to what is observed, or ought to be observed, in the clinic. This chapter describes the changes that occur in normal and malignant tissues during and after therapeutic irradiation as exemplified by treatments at the Christie Hospital. It is in no way intended as a substitute for the more comprehensive introductions to radiobiology which are to be found elsewhere. This chapter is intended to be interpretive with respect to current Christie Hospital clinical practice. For example, in the past, the authors chose not to participate in the evaluation of certain alleged advances in radiotherapy (most notably the use of the hyperbaric oxygen tank) though for some years a neutron generator was in clinical use at the Christie Hospital. Some of the radiobiological considerations behind these decisions are also discussed

  19. In vivo tumor radiobiology of heavy charged particles

    International Nuclear Information System (INIS)

    Curtis, S.B.; Tenforde, T.S.

    1980-01-01

    The response of tumor cells systems to irradiation with carbon, neon and argon beams at various positions in the plateau and extended-peak regions of the Bragg ionization curve is being evaluated from experiments conducted both in vivo and in vitro. The radiobiological end points being studied include: tumor volume response, cellular survival after tumor irradiation in situ, and cell-kinetic parameters

  20. Pulsed radiobiology with laser-driven plasma accelerators

    Science.gov (United States)

    Giulietti, Antonio; Grazia Andreassi, Maria; Greco, Carlo

    2011-05-01

    Recently, a high efficiency regime of acceleration in laser plasmas has been discovered, allowing table top equipment to deliver doses of interest for radiotherapy with electron bunches of suitable kinetic energy. In view of an R&D program aimed to the realization of an innovative class of accelerators for medical uses, a radiobiological validation is needed. At the present time, the biological effects of electron bunches from the laser-driven electron accelerator are largely unknown. In radiobiology and radiotherapy, it is known that the early spatial distribution of energy deposition following ionizing radiation interactions with DNA molecule is crucial for the prediction of damages at cellular or tissue levels and during the clinical responses to this irradiation. The purpose of the present study is to evaluate the radio-biological effects obtained with electron bunches from a laser-driven electron accelerator compared with bunches coming from a IORT-dedicated medical Radio-frequency based linac's on human cells by the cytokinesis block micronucleus assay (CBMN). To this purpose a multidisciplinary team including radiotherapists, biologists, medical physicists, laser and plasma physicists is working at CNR Campus and University of Pisa. Dose on samples is delivered alternatively by the "laser-linac" operating at ILIL lab of Istituto Nazionale di Ottica and an RF-linac operating for IORT at Pisa S. Chiara Hospital. Experimental data are analyzed on the basis of suitable radiobiological models as well as with numerical simulation based on Monte Carlo codes. Possible collective effects are also considered in the case of ultrashort, ultradense bunches of ionizing radiation.

  1. Experimental radiotherapy and clinical radiobiology. Vol. 20. Proceedings; Experimentelle Strahlentherapie und Klinische Strahlenbiologie. Bd. 20. Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Baumann, Michael; Dahm-Daphi, Jochen; Dikomey, Ekkehard; Petersen, Cordula; Rodemannn, Hans-Peter; Zips, Daniel (eds.)

    2011-07-01

    The proceedings include contributions on the following issues: laser driven proton accelerators on the way for radiotherapy, radiobiological evaluation of new radiations; molecular factors of radiation response; biological targeting; EGFR epidermal growth factor receptor/targeting - combined internal and external irradiation, radiobiology of normal tissues; dose-volume histograms for the radiotherapy: curves without radiobiological relevance or important information for the therapy planning; HPV (human papilloma virus) and radiation sensitivity of HNSCC (head and neck squamous cell carcinomas): evidence, radiobiological mechanism, clinical consequences and perspectives; mechanisms of action and intertumoral heterogeneity of response to EGFR inhibition in radiotherapy of solid tumors; evaluation of biomarkers for radiotherapy.

  2. Theory of targets and modern radiobiology

    International Nuclear Information System (INIS)

    Krasavin, E.A.; Kozubek, S.

    1988-01-01

    Detailed analysis of the history of classical radiobiology concepts was carried out and N.V. Timofeev-Resovskiy leading role in the formation of cell radiobiology was shown. Synthesis of penetration principle, target theory, microdosimetry, genetics and molecular radiobiology, disclosure of damage mechanisms of cell DNA by ionizing different LET radiation of, as well as, main mechanisms of cell repair have allowed to explain the nature of cell all radiobiological reactions

  3. Modern concepts for basic radiobiological factors characterizing tumor tissue radiosensitivity

    International Nuclear Information System (INIS)

    Gocheva, L.; Sergieva, K.

    2002-01-01

    Traditionally radiotherapy is prescribed at doses consistent with the expected therapeutic response and tolerance of tumor and normal tissues without consideration to individual differences in radiosensitivity. However, the basic radiobiological knowledge and clinical experience along this line point to significant variations in the observed therapeutic results. It has been established that cells and tissues under experimental and clinical conditions manifest a wide spectrum of individual radiosensitivity. The aim of this survey is to outline the current concepts for the basic radiobiological factors influencing tumor radiosensitivity. A thorough discussion is done of the essence, mechanisms of action, methods of determination and measurement, and effect on the prognosis in patients with malignant diseases of a number of radiobiological factors, such as: tumor-cell proliferation, apoptosis, tumor hypoxia and neovascularization. Although the knowledge of the mechanisms of radiosensitivity is constantly expanding, its clinical implementation is still rather limited. The true role of radiosensitivity in predicting the therapeutic response should be more accurately defined. (authors)

  4. Overview of research and therapy facilities for radiobiological experimental work in particle therapy. Report from the European Particle Therapy Network radiobiology group.

    Science.gov (United States)

    Dosanjh, Manjit; Jones, Bleddyn; Pawelke, Jörg; Pruschy, Martin; Sørensen, Brita Singers

    2018-04-24

    Particle therapy (PT) as cancer treatment, using protons or heavier ions, can provide a more favorable dose distribution compared to X-rays. While the physical characteristics of particle radiation have been the aim of intense research, less focus has been placed on the actual biological responses arising from particle irradiation. One of the biggest challenges for proton radiobiology is the RBE, with an increasing concern that the clinically-applied generic RBE-value of 1.1 is an approximation, as RBE is a complex quantity, depending on both biological and physical parameters, such as dose, LET, cellular and tissue radiobiological characteristics, as well as the endpoints being studied. Most of the available RBE data derive from in vitro experiments, with very limited in vivo data available, especially in late-reacting tissues, which provide the main constraints and influence the quality of life endpoints in radiotherapy. There is a need for systematic, large-scale studies to thoroughly establish the biology of particle radiation in a number of different experimental models in order to refine biophysical mathematical models that can potentially be used to guide PT. The overall objective of the European Particle Therapy Network (EPTN) WP6 is to form a network of research and therapy facilities in order to coordinate and standardize the radiobiological experiments, to obtain more accurate predictive parameters than in the past. Coordinated research is required in order to obtain the most appropriate experimental data. The aim in this paper is to describe the available radiobiology infrastructure of the centers involved in EPTN WP6. Copyright © 2018 Elsevier B.V. All rights reserved.

  5. Comparative radiobiology of genetic loci of eukaryots as the basis of the general theory of mutations

    International Nuclear Information System (INIS)

    Aleksandrov, I.D.

    1983-01-01

    One of the fundamental problems of modern molecular cellular radiobiology is to reveal general and peculiar processes of the formation of gene mutations and chromosome aberrations in each stage of their formation in the irradiated genome of the higher eukaryots. The solution of the problems depends on the development of research within the framework of comparative radiobiology of genetic loci of the higher eukaryots that makes it possible to study quantitative regularities in the formation of gene (point) mutations and chromosome aberrations in one object and in the same experiment

  6. Radiation Protection Research: Radiobiology

    International Nuclear Information System (INIS)

    Desaintes, C.

    2000-01-01

    The main objectives of research in the field of radiobiology and epidemiology performed at the Belgian Nuclear Research Centre SCK-CEN are (1) to study cancer mortality in nuclear workers in Belgium; to document the feasibility of retrospective cohort studies in Belgium; (2) to participate in the IARC study; (3) to elucidate the molecular basis of the effects of ionising radiation in the mammalian embryo during the early phases of its development; (4) to assess the genetic risk of maternal exposure to ionizing radiation; (5) to elucidate the cellular mechanisms leading to brain damage after prenatal irradiation; (6) to advise authorities and to provide the general population with adequate information concerning the health risk arising from radiation exposure. Progress and major achievements in these topical areas in 1999 are reported

  7. Radiation Protection Research: Radiobiology

    Energy Technology Data Exchange (ETDEWEB)

    Desaintes, C

    2000-07-01

    The main objectives of research in the field of radiobiology and epidemiology performed at the Belgian Nuclear Research Centre SCK-CEN are (1) to study cancer mortality in nuclear workers in Belgium; to document the feasibility of retrospective cohort studies in Belgium; (2) to participate in the IARC study; (3) to elucidate the molecular basis of the effects of ionising radiation in the mammalian embryo during the early phases of its development; (4) to assess the genetic risk of maternal exposure to ionizing radiation; (5) to elucidate the cellular mechanisms leading to brain damage after prenatal irradiation; (6) to advise authorities and to provide the general population with adequate information concerning the health risk arising from radiation exposure. Progress and major achievements in these topical areas in 1999 are reported.

  8. Development of a compact laser-produced plasma soft X-ray source for radiobiology experiments

    Energy Technology Data Exchange (ETDEWEB)

    Adjei, Daniel, E-mail: nana.adjeidan@gmail.com [Institute of Optoelectronics, Military University of Technology, 2, Kaliskiego Str., 00-908 Warsaw (Poland); Radiation Protection Institute, Ghana Atomic Energy Commission, P.O. Box LG 80, Legon, Accra (Ghana); Ayele, Mesfin Getachew; Wachulak, Przemyslaw; Bartnik, Andrzej; Wegrzynski, Łukasz; Fiedorowicz, Henryk [Institute of Optoelectronics, Military University of Technology, 2, Kaliskiego Str., 00-908 Warsaw (Poland); Vyšín, Luděk [Institute of Physics, Czech Academy of Sciences, Na Slovance 2, 182 21 Prague 8 (Czech Republic); Faculty of Nuclear Sciences and Engineering Physics, Czech Technical University in Prague, Břehová 7, 115 19 Prague 1 (Czech Republic); Wiechec, Anna; Lekki, Janusz; Kwiatek, Wojciech M. [Institute of Nuclear Physics, Polish Academy of Sciences, 152, Radzikowskiego Str., 31-342 Cracow (Poland); Pina, Ladislav [Faculty of Nuclear Sciences and Engineering Physics, Czech Technical University in Prague, Břehová 7, 115 19 Prague 1 (Czech Republic); Davídková, Marie [Institute of Nuclear Physics, Czech Academy of Sciences, Řež (Czech Republic); Juha, Libor [Institute of Physics, Czech Academy of Sciences, Na Slovance 2, 182 21 Prague 8 (Czech Republic)

    2015-12-01

    A desk-top laser-produced plasma (LPP) source of soft X-rays (SXR) has been developed for radiobiology research. The source is based on a double-stream gas puff target, irradiated with the focused beam of a commercial Nd:YAG laser. The source has been optimized to get a maximum photon emission from LPP in the X-ray “water window” spectral wavelength range from 2.3 nm (i.e., an absorption edge of oxygen) to 4.4 nm (i.e., an absorption edge of carbon) (280–540 eV in photon energy units) by using argon gas-puff target and spectral filtering by free-standing thin foils. The present source delivers nanosecond pulses of soft X-rays at a fluence of about 4.2 × 10{sup 3} photons/μm{sup 2}/pulse on a sample placed inside the vacuum chamber. In this paper, the source design, radiation output characterization measurements and initial irradiation experiments are described. The source can be useful in addressing observations related to biomolecular, cellular and organisms’ sensitivity to pulsed radiation in the “water window”, where carbon atoms absorb X-rays more strongly than the oxygen, mostly present in water. The combination of the SXR source and the radiobiology irradiation layout, reported in this article, make possible a systematic investigation of relationships between direct and indirect action of ionizing radiation, an increase of a local dose in carbon-rich compartments of the cell (e.g., lipid membranes), an experimental estimation of a particular role of the Auger effect (in particular in carbon atoms) in the damage to biological systems, and the study of ionization/excitation-density (LET – Linear Energy Transfer) and dose-rate effects in radiobiology.

  9. Radiobiology and Epidemiology

    International Nuclear Information System (INIS)

    Desaintes, C; Holmstock, L.

    2001-01-01

    The main objectives of research in the field of radiobiology and epidemiology performed at the Belgian Nuclear Research Centre SCK-CEN are: (1) to study cancer mortality in nuclear workers in Belgium and to co-ordinate the Belgian contribution to the 'International Collaborative Study of Cancer Risk among Radiation Workers in the Nuclear Industry'; (2) to elucidate the molecular basis of individual susceptibility to ionizing radiation in mammalian embryo during the early phases of its development; (3) to assess the genetic risk of maternal exposure to ionizing radiation; (4) to elucidate the cellular mechanisms leading to brain damage after prenatal irradiation; (5) to monitor the early variations of gene expression induced by ionising radiation and cytokines; (6) to evaluate the use of cytokines and natural substances for improving radiotherapy protocols; (6) to advise authorities and to provide the general population with adequate information concerning the health risk arising from radiation exposure. Progress and major achievements in these topical areas in 2000 are reported

  10. Radiobiology and Epidemiology

    Energy Technology Data Exchange (ETDEWEB)

    Desaintes, C; Holmstock, L

    2001-04-01

    The main objectives of research in the field of radiobiology and epidemiology performed at the Belgian Nuclear Research Centre SCK-CEN are: (1) to study cancer mortality in nuclear workers in Belgium and to co-ordinate the Belgian contribution to the 'International Collaborative Study of Cancer Risk among Radiation Workers in the Nuclear Industry'; (2) to elucidate the molecular basis of individual susceptibility to ionizing radiation in mammalian embryo during the early phases of its development; (3) to assess the genetic risk of maternal exposure to ionizing radiation; (4) to elucidate the cellular mechanisms leading to brain damage after prenatal irradiation; (5) to monitor the early variations of gene expression induced by ionising radiation and cytokines; (6) to evaluate the use of cytokines and natural substances for improving radiotherapy protocols; (6) to advise authorities and to provide the general population with adequate information concerning the health risk arising from radiation exposure. Progress and major achievements in these topical areas in 2000 are reported.

  11. The Future of Radiobiology.

    Science.gov (United States)

    Kirsch, David G; Diehn, Max; Kesarwala, Aparna H; Maity, Amit; Morgan, Meredith A; Schwarz, Julie K; Bristow, Robert; Demaria, Sandra; Eke, Iris; Griffin, Robert J; Haas-Kogan, Daphne; Higgins, Geoff S; Kimmelman, Alec C; Kimple, Randall J; Lombaert, Isabelle M; Ma, Li; Marples, Brian; Pajonk, Frank; Park, Catherine C; Schaue, Dörthe; Bernhard, Eric J

    2018-04-01

    Innovation and progress in radiation oncology depend on discovery and insights realized through research in radiation biology. Radiobiology research has led to fundamental scientific insights, from the discovery of stem/progenitor cells to the definition of signal transduction pathways activated by ionizing radiation that are now recognized as integral to the DNA damage response (DDR). Radiobiological discoveries are guiding clinical trials that test radiation therapy combined with inhibitors of the DDR kinases DNA-dependent protein kinase (DNA-PK), ataxia telangiectasia mutated (ATM), ataxia telangiectasia related (ATR), and immune or cell cycle checkpoint inhibitors. To maintain scientific and clinical relevance, the field of radiation biology must overcome challenges in research workforce, training, and funding. The National Cancer Institute convened a workshop to discuss the role of radiobiology research and radiation biologists in the future scientific enterprise. Here, we review the discussions of current radiation oncology research approaches and areas of scientific focus considered important for rapid progress in radiation sciences and the continued contribution of radiobiology to radiation oncology and the broader biomedical research community.

  12. Radiotherapy treatment planning linear-quadratic radiobiology

    CERN Document Server

    Chapman, J Donald

    2015-01-01

    Understand Quantitative Radiobiology from a Radiation Biophysics PerspectiveIn the field of radiobiology, the linear-quadratic (LQ) equation has become the standard for defining radiation-induced cell killing. Radiotherapy Treatment Planning: Linear-Quadratic Radiobiology describes tumor cell inactivation from a radiation physics perspective and offers appropriate LQ parameters for modeling tumor and normal tissue responses.Explore the Latest Cell Killing Numbers for Defining Iso-Effective Cancer TreatmentsThe book compil

  13. Quantitative clinical radiobiology

    International Nuclear Information System (INIS)

    Bentzen, S.M.

    1993-01-01

    Based on a series of recent papers, a status is given of our current ability to quantify the radiobiology of human tumors and normal tissues. Progress has been made in the methods of analysis. This includes the introduction of 'direct' (maximum likelihood) analysis, incorporation of latent-time in the analyses, and statistical approaches to allow for the many factors of importance in predicting tumor-control probability of normal-tissue complications. Quantitative clinical radiobiology of normal tissues is reviewed with emphasis on fractionation sensitivity, repair kinetics, regeneration, latency, and the steepness of dose-response curves. In addition, combined modality treatment, functional endpoints, and the search for a correlation between the occurrence of different endpoints in the same individual are discussed. For tumors, quantitative analyses of fractionation sensitivity, repair kinetics, reoxygenation, and regeneration are reviewed. Other factors influencing local control are: Tumor volume, histopathologic differentiation and hemoglobin concentration. Also, the steepness of the dose-response curve for tumors is discussed. Radiobiological strategies for improving radiotherapy are discussed with emphasis on non-standard fractionation and individualization of treatment schedules. (orig.)

  14. Radiobiology of normal tissue. Scientific advances and perspectives; Strahlenbiologie der Normalgewebe. Wissenschaftliche Fortschritte und Perspektiven

    Energy Technology Data Exchange (ETDEWEB)

    Doerr, W. [Medizinische Univ. Wien (Austria). Universitaetsklinik fuer Strahlentherapie; Medizinische Univ. Wien (Austria). Universitaetsklinik fuer Radioonkologie; Medizinische Univ. Wien (Austria). Christian Doppler Labor fuer Medizinische Strahlenforschung fuer die Radioonkologie; Herskind, C. [Universitaetsmedizin Mannheim, Heidelberg Univ., Mannheim (Germany). Labor fuer Zellulaere und Molekulare Radioonkologie

    2012-11-15

    Radiotherapy involves always the exposure of normal tissue, resulting in an excepted risk of complications. The side effect rate is therefore the compromise between optimized tumor doses and the side effect minimization. The report covers the issues target cell hypothesis and the consequences, new aspect of the pathogenesis of normal issue reactions and strategies of targeted reduction of normal tissue effects. The complexity of the radiobiological processes, the specificity and action mechanisms, the mutual interactions of chemical and radiological processes require further coordinated radiobiological research in the future.

  15. Cellular radiobiology of heavy-ion beams

    International Nuclear Information System (INIS)

    Tobias, C.A.; Blakely, E.A.; Ngo, F.Q.H.; Roots, R.J.; Yang, T.C.

    1981-01-01

    Progress is reported in the following areas of this research program: relative biological effectiveness and oxygen enhancement ratio of silicon ion beams; heavy ion effects on the cell cycle; the potentiation effect (2 doses of high LET heavy-ion radiations separated by 2 to 3 hours); potentially lethal damage in actively growing cells and plateau growth cells; radiation induced macromolecular lesions and cellular radiation chemistry; lethal effects of dual radiation; and the development of a biophysical repair/misrepair model

  16. Radiobiological Optimization in Lung Stereotactic Body Radiation Therapy: Are We Ready to Apply Radiobiological Models?

    Directory of Open Access Journals (Sweden)

    Marco D’Andrea

    2018-01-01

    Full Text Available Lung tumors are often associated with a poor prognosis although different schedules and treatment modalities have been extensively tested in the clinical practice. The complexity of this disease and the use of combined therapeutic approaches have been investigated and the use of high dose-rates is emerging as effective strategy. Technological improvements of clinical linear accelerators allow combining high dose-rate and a more conformal dose delivery with accurate imaging modalities pre- and during therapy. This paper aims at reporting the state of the art and future direction in the use of radiobiological models and radiobiological-based optimizations in the clinical practice for the treatment of lung cancer. To address this issue, a search was carried out on PubMed database to identify potential papers reporting tumor control probability and normal tissue complication probability for lung tumors. Full articles were retrieved when the abstract was considered relevant, and only papers published in English language were considered. The bibliographies of retrieved papers were also searched and relevant articles included. At the state of the art, dose–response relationships have been reported in literature for local tumor control and survival in stage III non-small cell lung cancer. Due to the lack of published radiobiological models for SBRT, several authors used dose constraints and models derived for conventional fractionation schemes. Recently, several radiobiological models and parameters for SBRT have been published and could be used in prospective trials although external validations are recommended to improve the robustness of model predictive capability. Moreover, radiobiological-based functions have been used within treatment planning systems for plan optimization but the advantages of using this strategy in the clinical practice are still under discussion. Future research should be directed toward combined regimens, in order to

  17. The radiobiology of laser-driven particle beams: focus on sub-lethal responses of normal human cells

    International Nuclear Information System (INIS)

    Manti, L.; Perozziello, F.M.; Romagnani, L.; Borghesi, M.; Doria, D.; Candiano, G.; Cirrone, G.A.P.; Leanza, R.; Romano, F.; Scuderi, V.; Tramontana, A.; Chaudhary, P.; Gwynne, D.; Prise, K. M.

    2017-01-01

    Accelerated proton beams have become increasingly common for treating cancer. The need for cost and size reduction of particle accelerating machines has led to the pioneering investigation of optical ion acceleration techniques based on laser-plasma interactions as a possible alternative. Laser-matter interaction can produce extremely pulsed particle bursts of ultra-high dose rates (≥ 10 9 Gy/s), largely exceeding those currently used in conventional proton therapy. Since biological effects of ionizing radiation are strongly affected by the spatio-temporal distribution of DNA-damaging events, the unprecedented physical features of such beams may modify cellular and tissue radiosensitivity to unexplored extents. Hence, clinical applications of laser-generated particles need thorough assessment of their radiobiological effectiveness. To date, the majority of studies have either used rodent cell lines or have focussed on cancer cell killing being local tumour control the main objective of radiotherapy. Conversely, very little data exist on sub-lethal cellular effects, of relevance to normal tissue integrity and secondary cancers, such as premature cellular senescence. Here, we discuss ultra-high dose rate radiobiology and present preliminary data obtained in normal human cells following irradiation by laser-accelerated protons at the LULI PICO2000 facility at Laser Lab Europe, France.

  18. Basics of radiobiology and nuclear medicine

    International Nuclear Information System (INIS)

    Kostadinova, I.; Hadjidekova, V.; Georgieva, R.

    2002-01-01

    The authors successively reveal the topics of the biological impact of radiation (radiobiology) and the diagnostic and the therapeutic application of radiopharmaceuticals (nuclear medicine). Data on the influence of radiation on subcellular, cellular, tissue and organ level are given, on early and late radiation changes, as well. Indication for the application of the different radionuclide methods in the diagnosis of the diseases in the endocrinology, nephrology, cardiology, gastroenterology, haematology of lungs, bones, tumors are pointed out and the main trends of the growing therapeutical use of nuclear medicine are presented. The aim is to teach students the nuclear medicine methods in the complex investigation of the patients, his preliminary preparation and the biological impact of radiation and its risk. Self assessment test for students are proposed and a literature for further reading

  19. Radiobiological analyse based on cell cluster models

    International Nuclear Information System (INIS)

    Lin Hui; Jing Jia; Meng Damin; Xu Yuanying; Xu Liangfeng

    2010-01-01

    The influence of cell cluster dimension on EUD and TCP for targeted radionuclide therapy was studied using the radiobiological method. The radiobiological features of tumor with activity-lack in core were evaluated and analyzed by associating EUD, TCP and SF.The results show that EUD will increase with the increase of tumor dimension under the activity homogeneous distribution. If the extra-cellular activity was taken into consideration, the EUD will increase 47%. Under the activity-lack in tumor center and the requirement of TCP=0.90, the α cross-fire influence of 211 At could make up the maximum(48 μm)3 activity-lack for Nucleus source, but(72 μm)3 for Cytoplasm, Cell Surface, Cell and Voxel sources. In clinic,the physician could prefer the suggested dose of Cell Surface source in case of the future of local tumor control for under-dose. Generally TCP could well exhibit the effect difference between under-dose and due-dose, but not between due-dose and over-dose, which makes TCP more suitable for the therapy plan choice. EUD could well exhibit the difference between different models and activity distributions,which makes it more suitable for the research work. When the user uses EUD to study the influence of activity inhomogeneous distribution, one should keep the consistency of the configuration and volume of the former and the latter models. (authors)

  20. Evaluation of radiobiological effects in 3 distinct biological models

    International Nuclear Information System (INIS)

    Lemos, J.; Costa, P.; Cunha, L.; Metello, L.F.; Carvalho, A.P.; Vasconcelos, V.; Genesio, P.; Ponte, F.; Costa, P.S.; Crespo, P.

    2015-01-01

    Full text of publication follows. The present work aims at sharing the process of development of advanced biological models to study radiobiological effects. Recognizing several known limitations and difficulties of the current monolayer cellular models, as well as the increasing difficulties to use advanced biological models, our group has been developing advanced biological alternative models, namely three-dimensional cell cultures and a less explored animal model (the Zebra fish - Danio rerio - which allows the access to inter-generational data, while characterized by a great genetic homology towards the humans). These 3 models (monolayer cellular model, three-dimensional cell cultures and zebra fish) were externally irradiated with 100 mGy, 500 mGy or 1 Gy. The consequences of that irradiation were studied using cellular and molecular tests. Our previous experimental studies with 100 mGy external gamma irradiation of HepG2 monolayer cells showed a slight increase in the proliferation rate 24 h, 48 h and 72 h post irradiation. These results also pointed into the presence of certain bystander effects 72 h post irradiation, constituting the starting point for the need of a more accurate analysis realized with this work. At this stage, we continue focused on the acute biological effects. Obtained results, namely MTT and clonogenic assays for evaluating cellular metabolic activity and proliferation in the in vitro models, as well as proteomics for the evaluation of in vivo effects will be presented, discussed and explained. Several hypotheses will be presented and defended based on the facts previously demonstrated. This work aims at sharing the actual state and the results already available from this medium-term project, building the proof of the added value on applying these advanced models, while demonstrating the strongest and weakest points from all of them (so allowing the comparison between them and to base the subsequent choice for research groups starting

  1. Beneficial liaisons: radiobiology meets cellular and molecular biology

    International Nuclear Information System (INIS)

    Stevenson, Mary Ann; Coleman, C. Norman

    1995-01-01

    Purpose: The purpose of this course is to familiarize radiation oncologists with the concepts and terminology and molecular and cellular biology that are especially relevant to radiation oncology. The ability of radiation oncologists to remain current with the new discoveries of modern biology is essential to the development of improved therapeutic strategies and, importantly, to the proper balance between investment in technology and biology. Objective: This year, this Refresher Course is part of a three-part ''series'' including Drs. Martin Brown and Amato Giaccia. The objective is to provide continuing education for the academic and practicing radiation oncologist, physicist and biologist in the modern biologic concepts of cancer and its treatment. An effort will be made to relate these general concepts to the clinic by providing a broad view as to potential new biological treatments which might enhance the efficacy of radiation therapy. The specific focus of this Course will vary from year to year. Some of the classic radiation biology models which form the basis of clinical practice and laboratory research will be examined and 'newer' models will be presented which take into account the emerging knowledge of cellular and molecular biology. A few techniques in molecular and cellular biology will be described to the extent necessary to understand their basic concepts and their applicability. Aspects of radiation biology which will be covered include cell cycle, radiation-induced changes in the cellular phenotype, and considerations of the effect of the tumor microenvironment. It is not the expectation that the attendees will become experts in the particular subjects presented. Rather, it is the intent to increase their curiosity as to the new knowledge that is emerging and to demonstrate that these seemingly complicated areas can be understood and appreciated with a modicum of the effort

  2. Checking the foundation: recent radiobiology and the linear no-threshold theory.

    Science.gov (United States)

    Ulsh, Brant A

    2010-12-01

    The linear no-threshold (LNT) theory has been adopted as the foundation of radiation protection standards and risk estimation for several decades. The "microdosimetric argument" has been offered in support of the LNT theory. This argument postulates that energy is deposited in critical cellular targets by radiation in a linear fashion across all doses down to zero, and that this in turn implies a linear relationship between dose and biological effect across all doses. This paper examines whether the microdosimetric argument holds at the lowest levels of biological organization following low dose, low dose-rate exposures to ionizing radiation. The assumptions of the microdosimetric argument are evaluated in light of recent radiobiological studies on radiation damage in biological molecules and cellular and tissue level responses to radiation damage. There is strong evidence that radiation initially deposits energy in biological molecules (e.g., DNA) in a linear fashion, and that this energy deposition results in various forms of prompt DNA damage that may be produced in a pattern that is distinct from endogenous (e.g., oxidative) damage. However, a large and rapidly growing body of radiobiological evidence indicates that cell and tissue level responses to this damage, particularly at low doses and/or dose-rates, are nonlinear and may exhibit thresholds. To the extent that responses observed at lower levels of biological organization in vitro are predictive of carcinogenesis observed in vivo, this evidence directly contradicts the assumptions upon which the microdosimetric argument is based.

  3. Radiobiology: Biologic effects of ionizing radiations

    International Nuclear Information System (INIS)

    Held, K.D.

    1987-01-01

    The biologic effects after exposure to ionizing radiation, such as cell death or tissue injury, result from a chain of complex physical, chemical, metabolic, and histologic events. The time scale of these radiation actions spans many orders of magnitude. The physical absorption of ionizing radiation occurs in about 10 -18 s, while late carcinogenic and genetic effects are expressed years or even generations later. Collectively, these effects form the science of radiobiology. Many of the concepts discussed in this chapter have been developed through the study of effects generated in tissues by external radiation sources, but they apply generally and often specifically to internally distributed radiopharmaceuticals which form the central topic of this book

  4. An irradiation facility with a horizontal beam for radiobiological studies

    International Nuclear Information System (INIS)

    Czub, J.; Adamus, T.; Banas, D.

    2006-01-01

    A facility with a horizontal beam for radiobiological experiments with heavy ions has been designed and constructed at the Heavy Ion Laboratory in Warsaw University. The facility is optimal to investigate the radiobiological effects of charged heavy particles on a cellular or molecular level as the plateau of the Bragg curve as well as in the Bragg peak. The passive beam spread out by a thin scattering foil provides a homogeneous irradiation field over an area of at least 1 x 1 cm 2 . For in vitro irradiation of biological samples the passive beam spreading combined with the x - y mechanical scanning of the irradiated sample was found to be an optimum solution. Using x - y step motor, the homogenous beam of ions with the energy loss range in the cells varied from 1 MeV/μm to 200 keV/μm is able to cover a 6 cm in diameter Petri dish that holds the biological samples. Moreover on-line fluence monitoring based on single-particle counting is performed to determine the dose absorbed by cells. Data acquisition system for dosimetry and ion monitoring based on a personal computer is described. (author)

  5. DMPD: Anti-inflammatory actions of PPAR ligands: new insights on cellular andmolecular mechanisms. [Dynamic Macrophage Pathway CSML Database

    Lifescience Database Archive (English)

    Full Text Available 17981503 Anti-inflammatory actions of PPAR ligands: new insights on cellular andmol...) (.html) (.csml) Show Anti-inflammatory actions of PPAR ligands: new insights on cellular andmolecular mech...anisms. PubmedID 17981503 Title Anti-inflammatory actions of PPAR ligands: new insight

  6. Status and role of radiobiology in veterinary medicine

    International Nuclear Information System (INIS)

    Benova, K.

    2013-01-01

    In this presentation history of radiobiology in University of Veterinary Medicine and Pharmacy in Kosice from 1949 is presented. Scientific and pedagogic programs, role of veterinary physician as well as concept of radiobiology and cooperation are reviewed. Changes in Poecilia reticulata and Artemia franciscana after gamma radiation are presented.

  7. Combined hit theory-microdosimetric explanation of cellular radiobiological action

    International Nuclear Information System (INIS)

    Bond, V.P.; Varma, M.N.

    1983-01-01

    Hit theory is combined with microdosimetry in a stochastic approach that explains the observed responses of cell populations exposed in radiation fields of different qualities. The central thesis is that to expose a population of cells in a low-level radiation field is to subject the cells to the potential for interaction with charged particles in the vicinity of the cells, quantifiable in terms of the charged particle fluence theta. When such an interaction occurs there is a resulting stochastic transfer of energy to a critical volume (CV) of cross section sigma, within the cell(s). The severity of cell injury is dependent on the amount of energy thus imparted, or the hit size. If the severity is above some minimal level, there is a non-zero probability that the injury will result in a quantal effect (e.g., a mutational or carcinogenic initial event, cell transformation). A microdosimetric proportional counter, viewed here as a phantom cell CV that permits measurements not possible in the living cell, is used to determine the incidence of hit cells and the spectrum of hit sizes. Each hit is then weighted on the basis of an empirically-determined function that provides the fraction of cells responding quantally, as a function of hit size. The sum of the hits so weighted provides the incidence of quantally-responding cells, for any amount of exposure theta in a radiation field of any quality or mixture qualities. The hit size weighting function for pink mutations in Tradescantia is discussed, as are its implications in terms of a replacement for RBE and dose equivalent. 14 references, 9 figures

  8. Radiobiology software for educational purpose

    International Nuclear Information System (INIS)

    Pandey, A.K.; Sharma, S.K.; Kumar, R.; Bal, C.S.; Nair, O.; Haresh, K.P.; Julka, P.K.

    2014-01-01

    To understand radio-nuclide therapy and the basis of radiation protection, it is essential to understand radiobiology. With limited time for classroom teaching and limited time and resources for radiobiology experiments students do not acquire firm grasp of theoretical mathematical models and experimental knowledge of target theory and Linear quadratic models that explain nature of cell survival curves. We believe that this issue might be addressed with numerical simulation of cell survival curves using mathematical models. Existing classroom teaching can be reoriented to understand the subject using the concept of modeling, simulation and virtual experiments. After completion of the lecture, students can practice with simulation tool at their convenient time. In this study we have developed software that can help the students to acquire firm grasp of theoretical and experimental radiobiology. The software was developed using FreeMat ver 4.0, open source software. Target theory, linear quadratic model, cell killing based on Poisson model have been included. The implementation of the program structure was to display the menu for the user choice to be made and then program flows depending on the users choice. The program executes by typing 'Radiobiology' on the command line interface. Students can investigate the effect of radiation dose on cell, interactively. They can practice to draw the cell survival curve based on the input and output data and they can also compare their handmade graphs with automatically generated graphs by the program. This software is in the early stage of development and will evolve on user feedback. We feel this simulation software will be quite useful for students entering in the nuclear medicine, radiology and radiotherapy disciplines. (author)

  9. Toward a national consensus: teaching radiobiology to radiation oncology residents

    International Nuclear Information System (INIS)

    Zeman, Elaine M.; Dynlacht, Joseph R.; Rosenstein, Barry S.; Dewhirst, Mark W.

    2002-01-01

    Purpose: The ASTRO Joint Working Group on Radiobiology Teaching, a committee composed of members having affiliations with several national radiation oncology and biology-related societies and organizations, commissioned a survey designed to address issues of manpower, curriculum standardization, and instructor feedback as they relate to resident training in radiation biology. Methods and Materials: Radiation biology instructors at U.S. radiation oncology training programs were identified and asked to respond to a comprehensive electronic questionnaire dealing with instructor educational background, radiation biology course content, and sources of feedback with respect to curriculum planning and resident performance on standardized radiation biology examinations. Results: Eighty-five radiation biology instructors were identified, representing 73 radiation oncology residency training programs. A total of 52 analyzable responses to the questionnaire were received, corresponding to a response rate of 61.2%. Conclusion: There is a decreasing supply of instructors qualified to teach classic, and to some extent, clinical, radiobiology to radiation oncology residents. Additionally, those instructors with classic training in radiobiology are less likely to be comfortable teaching cancer molecular biology or other topics in cancer biology. Thus, a gap exists in teaching the whole complement of cancer and radiobiology curricula, particularly in those programs in which the sole responsibility for teaching falls to one faculty member (50% of training programs are in this category). On average, the percentage of total teaching time devoted to classic radiobiology (50%), clinical radiobiology (30%), and molecular and cancer biology (20%) is appropriate, relative to the current makeup of the board examination. Nevertheless large variability exists between training programs with respect to the total number of contact hours per complete radiobiology course (ranging from

  10. Cellular and Molecular Targets of Menthol Actions

    Directory of Open Access Journals (Sweden)

    Murat Oz

    2017-07-01

    Full Text Available Menthol belongs to monoterpene class of a structurally diverse group of phytochemicals found in plant-derived essential oils. Menthol is widely used in pharmaceuticals, confectionary, oral hygiene products, pesticides, cosmetics, and as a flavoring agent. In addition, menthol is known to have antioxidant, anti-inflammatory, and analgesic effects. Recently, there has been renewed awareness in comprehending the biological and pharmacological effects of menthol. TRP channels have been demonstrated to mediate the cooling actions of menthol. There has been new evidence demonstrating that menthol can significantly influence the functional characteristics of a number of different kinds of ligand and voltage-gated ion channels, indicating that at least some of the biological and pharmacological effects of menthol can be mediated by alterations in cellular excitability. In this article, we examine the results of earlier studies on the actions of menthol with voltage and ligand-gated ion channels.

  11. National Radiobiology Archives distributed access programmer's guide

    International Nuclear Information System (INIS)

    Prather, J.C.; Smith, S.K.; Watson, C.R.

    1991-12-01

    The National Radiobiology Archives is a comprehensive effort to gather, organize, and catalog original data, representative specimens, and supporting materials related to significant radiobiology studies. This provides researchers with information for analyses which compare or combine results of these and other studies and with materials for analysis by advanced molecular biology techniques. This Programmer's Guide document describes the database access software, NRADEMO, and the subset loading script NRADEMO/MAINT/MAINTAIN, which comprise the National Laboratory Archives Distributed Access Package. The guide is intended for use by an experienced database management specialist. It contains information about the physical and logical organization of the software and data files. It also contains printouts of all the scripts and associated batch processing files. It is part of a suite of documents published by the National Radiobiology Archives

  12. Research in Radiobiology

    International Nuclear Information System (INIS)

    Miller, S.C.; Buster, D.S.

    1988-01-01

    This document contains the tables of contents for the reports published by the University of Utah Radiobiology Laboratory from 1953--1987. Also included is a keyword index for the reports, and references for all books, book and symposia chapters and journal article published by Laboratory staff between 1950 and 1988

  13. Tumor radiobiology studies with heavy charged-particle beams

    International Nuclear Information System (INIS)

    Curtis, S.B.; Tenforde, T.S.; Tenforde, S.D.; Parr, S.S.; Flynn, M.J.

    1981-01-01

    The response of tumor-cell systems to irradiation with carbon, neon, and argon beams at various positions in the plateau and extended peak regions of the Bragg ionization (dose versus depth) curve is being evaluated from experiments conducted both in vivo and in vitro. The radiobiological end points being studied include: tumor volume response, cellular survival after tumor irradiation in situ, cell-kinetic parameters measured by flow cytofluorometry and time-lapse cinematography, and survival of oxic and hypoxic cells irradiated in suspension. One focus of the research effort during the past year has been on the combined effect of radiosensitizing drugs and charged-particle irradiation. In this article, the results are presented of studies on combined drug and radiation treatment of a rat rhabdomyosarcoma tumor and a human melanoma tumor growing in athymic (thymus-less) nude mice

  14. Impact of radiobiological considerations on epidemiological inferences of age-dependent radiosensitivity

    International Nuclear Information System (INIS)

    Crawford-Brown, D.J.

    1983-01-01

    Current epidemiological studies of the age-dependent risk of radiogenic carcinomas are based on populations still in the early stages of cancer expression. The result is a set of logical uncertainties concerning the manner in which inferences may be drawn from the existing data. These uncertainties may be formalized and examined through the application of various radiobiological principles developed from more fundamental experimental data. Chief amongst these considerations are the time course of tumor expression, the role of relative and absolute risk models, the distribution of effects between initiation and promotion, the age-dependent fraction of time a critical cell remains in radiosensitive stages and the combinatorics of the critical cellular subpopulations. Each of these and the combinatorics of the critical cellular subpopulations. Each of these principles are examined in light of their impact on the structuring of epidemiologic data and the drawing of inferences concerning age-dependent radiogenic risk. The data on atomic bomb survivors are employed as a relevant example

  15. Radiobiological studies with marine fish

    International Nuclear Information System (INIS)

    Pentreath, R.J.

    1975-01-01

    The experimental methodology employed in radiobiological studies with fish is discussed and reviewed. The problems of care and maintenance of healthy stock fish are cons. (author)idered, including the techniques of egg and larval rearing. A variety of methods have been used to study the accumulation and loss of radionuclides, including labelled water, food and injections, and their relative merits are discussed in conjunction with the parameters affecting these processes. Other, more specialized, techniques that aid the physiological interpretation of tracer experiments are also discussed. Finally, consideration is given to some of the mathematical models that have been applied to radiobiological studies with fish, and of their value in extrapolating laboratory data to environmental conditions

  16. Radiobiological input to radiation protection standards

    International Nuclear Information System (INIS)

    Bond, V.P.

    1981-01-01

    A brief review of the radiobiological data relevant to radiation protection standards is given. In particular the nature of the dose-response relationships for mutagenesis and carcinogenesis in animals and man is discussed with reference to the BEIR 1 1972, the NRC75, the UNSCEAR 77 and the NCRP80 Reports. It was concluded that the linear-no-threshold relationship for mutagenesis and carcinogenesis is too simple and that the relationship is best described by curves of varying slopes depending on the dose rate. By examining the data on the incidence of actual tumour systems in animals and man in relation to radiation dose, it was shown that the relationships developed in the simple Tradescantia single-cell system appear to hold widely throughout radiobiology. In developing radiation protection standards, first animal and human radiobiological data were used in determining an appropriate risk coefficient for late and genetic effects for the human being, and second an appropriate comparison of radiation and other more common risks was used as a basis for setting limits of incidence in the exposed population/individual. (U.K.)

  17. Perspectives of genetic engineering in radiobiology

    International Nuclear Information System (INIS)

    Khanson, K.P.; Zvonareva, N.B.; Evtushenko, V.I.

    1988-01-01

    Present evidence on the use of genetic engineering methods in studying the molecular mechanism of radiation damage and repair of DNA, as well as radiation mutagenesis and carcinogenesis has been summarized. The new approach to radiobiological research has proved to be extremely fruitful. Some previously unknown types of structural disorders in DNA molecule have been discovered, some repair genes isolated and their primary structure established, some aspects of radiation mutagenesis elucidated, and research into disiphering the molecular bases of neoplastic transformations of exposed cells are being successfully investigated. The perspectives of using genetic engineering methods in radiobiology are discussed

  18. Radiobiological considerations in the treatment of neuroblastoma by total body irradiation

    International Nuclear Information System (INIS)

    Wheldon, T.E.; O'Donoghue, J.; Gregor, A.; Livingstone, A.; Wilson, L.; West of Scotland Health Boards, Glasgow

    1986-01-01

    Neuroblastoma is a radiosensitive neoplasm for which total body irradiation (TBI) is presently under clinical consideration. Collated data on the radiobiology of human neuroblastoma cells in vitro indicates moderate cellular radiosensitivity and low capacity for accumulation of sublethal damage. Mathematical studies incorporating these parameters suggest that low dose fractionated TBI is unlikely to achieve significant levels of tumour cell kill. When high dose TBI is used in conjuction with bone marrow rescue a tumour 'log cell kill' of 4-5 should be achievable. This effect would be additional to that acheived by chemotherapy. Fractionated TBI with bone marrow rescue may be curative for some patients in clinical remission who are presently destined to relapse. (Auth.)

  19. Cellular and biochemical actions of adrenal glucocorticoid hormones on rat thymic lymphocytes.

    OpenAIRE

    Young, D A; Voris, B P; Nicholson, M L

    1981-01-01

    The molecular, biochemical, and cellular effects of adrenal glucocorticoid hormones on thymic lymphocytes are reviewed, with emphasis on their relationship to the growth suppressive and lethal actions that occur in lymphoid tissues when glucocorticoids are administered to the whole animal. The data support the hypothesis that the hormonal inhibition of growth and development is a consequence of its ability to suppress cellular energy production, causing the cells to behave as though they were...

  20. An introduction to radiobiology

    International Nuclear Information System (INIS)

    Nias, A.H.W.; Dimbleby, R.

    1990-01-01

    This text provides an introduction to quantitative radiobiology with emphasis on practical aspects of the subject. Among the topics considered are reparable damage, densely ionizing radiation, normal and malignant cells, and whole body regulation. These and other aspects of radiation biology are described in detail

  1. Inducing repetitive action potential firing in neurons via synthesized photoresponsive nanoscale cellular prostheses.

    Science.gov (United States)

    Lu, Siyuan; Madhukar, Anupam

    2013-02-01

    Recently we reported an analysis that examined the potential of synthesized photovoltaic functional abiotic nanosystems (PVFANs) to modulate membrane potential and activate action potential firing in neurons. Here we extend the analysis to delineate the requirements on the electronic energy levels and the attendant photophysical properties of the PVFANs to induce repetitive action potential under continuous light, a capability essential for the proposed potential application of PVFANs as retinal cellular prostheses to compensate for loss of photoreceptors. We find that repetitive action potential firing demands two basic characteristics in the electronic response of the PVFANs: an exponential dependence of the PVFAN excited state decay rate on the membrane potential and a three-state system such that, following photon absorption, the electron decay from the excited state to the ground state is via intermediate state(s) whose lifetime is comparable to the refractory time following an action potential. In this study, the potential of synthetic photovoltaic functional abiotic nanosystems (PVFANs) is examined under continuous light to modulate membrane potential and activate action potential firing in neurons with the proposed potential application of PVFANs as retinal cellular prostheses. Copyright © 2013 Elsevier Inc. All rights reserved.

  2. New radiobiological, radiation risk and radiation protection paradigms

    International Nuclear Information System (INIS)

    Goodhead, Dudley T.

    2010-01-01

    The long-standing conventional paradigm for radiobiology has formed a logical basis for the standard paradigm for radiation risk of cancer and heritable effects and, from these paradigms, has developed the internationally applied system for radiation protection, but with many simplifications, assumptions and generalizations. A variety of additional radiobiological phenomena that do not conform to the standard paradigm for radiobiology may have potential implications for radiation risk and radiation protection. It is suggested, however, that the current state of knowledge is still insufficient for these phenomena, individually or collectively, to be formulated systematically into a new paradigm for radiobiology. Additionally, there is at present lack of direct evidence of their relevance to risk for human health, despite attractive hypotheses as to how they might be involved. Finally, it remains to be shown how incorporation of such phenomena into the paradigm for radiation protection would provide sufficient added value to offset disruption to the present widely applied system. Further research should aim for better mechanistic understanding of processes such as radiation-induced genomic instability (for all radiation types) and bystander effects (particularly for low-fluence high-LET particles) and also priority should be given to confirmation, or negation, of the relevance of the processes to human health risks from radiation.

  3. Proceedings of the 4th Radiobiological conference with international participation 2008

    International Nuclear Information System (INIS)

    Benova, K.; Falis, M.

    2008-06-01

    Scientific conference deals with problems in radiobiology, photobiology and radio-environmental sciences. The Conference included the following sessions: (i): Radiobiology; (ii) Biology. Proceedings contains thirty-two papers dealing with the scope of INIS

  4. Radiobiological experiments at the Munich ion microbeam SNAKE

    Energy Technology Data Exchange (ETDEWEB)

    Friedl, A.A.; Drexler, G.A.; Loewe, R. [Strahlenbiologisches Inst., Ludwig-Maximilians-Univ. Muenchen (Germany); Dollinger, G.; Hauptner, A.; Hable, V.; Greubel, C.; Kruecken, R. [Physik Dept. E12, Technische Univ. Muenchen, Garching (Germany); Cremer, T.; Dietzel, S. [Dept. Biologie II, Ludwig-Maximilians-Univ. Muenchen, Planegg-Martinsried (Germany)

    2005-07-01

    The ion microbeam SNAKE at the Munich 14 MV tandem accelerator was recently adapted for irradiation of cells and is now routinely used for radiobiological experiments. Several features, including ion-optical beam focussing to achieve a targeting accuracy of about 500 nm, fast movement of the beam by electrostatic deflection and single ion preparation make SNAKE an excellent tool for localized irradiation with a defined number of ions. The ion spectrum available ranges from 20 MeV protons to 200 MeV gold ions, thus allowing to vary the LET over four orders of magnitude and to conduct low and high LET irradiation in a single experimental set-up. This offers the possibility of a systematic analysis of the cellular response mechanisms in their dependence on dose and LET. Other current lines of research include analysis of the spatio-temporal dynamics of protein recruitment at damaged chromatin sites and determination of the mobility of damaged chromatin regions in the interphase nucleus. (orig.)

  5. Practical Radiobiology for Proton Therapy Planning

    Science.gov (United States)

    Jones, Bleddyn

    2017-12-01

    Practical Radiobiology for Proton Therapy Planning covers the principles, advantages and potential pitfalls that occur in proton therapy, especially its radiobiological modelling applications. This book is intended to educate, inform and to stimulate further research questions. Additionally, it will help proton therapy centres when designing new treatments or when unintended errors or delays occur. The clear descriptions of useful equations for high LET particle beam applications, worked examples of many important clinical situations, and discussion of how proton therapy may be optimized are all important features of the text. This important book blends the relevant physics, biology and medical aspects of this multidisciplinary subject. Part of Series in Physics and Engineering in Medicine and Biology.

  6. A combined hit theory-microdosimetric explanation of cellular radiobiological action

    International Nuclear Information System (INIS)

    Bond, V.P.; Varma, M.N.

    1983-01-01

    Hit theory is combined with microdosimetry in a stochastic approach that explains the observed responses of cell populations exposed in radiation fields of different qualities. The central thesis is that to expose a population of cells in a low-level radiation field is to subject the cells to the potential for interaction with charged particles, quantifiable in terms of the charged particle fluence PHI. When such an interaction occurs there is resulting stochastic transfer of energy to a critical volume (CV) of cross-section σ within the cell(s). The severity of cell injury is dependent on the amount of energy thus imparted, or the hit size. If the severity is above some minimal level, there is a non-zero probability that the injury will result in a quantal effect (e.g., a mutational or carcinogenic initial event, cell transformation). A microdosimetric proportional counter, viewed here as a phantom cell CV that permits measurements not possible in the living cell, is used to determine the incidence of hit cells and the spectrum of hit sizes. Each hit is then weighted on the basis of an empirically determined function that provides the fraction of cells responding quantally, as a function of hit size. The sum of the hits so weighted provides the incidence of quantally responding cells, for any amount of exposure PHI in a radiation field of any quality or mixture of qualities. The hit size weighting function for pink mutations in Tradescantia is discussed, as are its implications in terms of a replacement for relative biological effectiveness and dose equivalent. (author)

  7. National Radiobiology Archives distributed access programmer's guide

    Energy Technology Data Exchange (ETDEWEB)

    Prather, J. C. [Linfield Coll., McMinnville, OR (United States); Smith, S. K.; Watson, C. R. [Pacific Northwest Lab., Richland, WA (United States)

    1991-12-01

    The National Radiobiology Archives is a comprehensive effort to gather, organize, and catalog original data, representative specimens, and supporting materials related to significant radiobiology studies. This provides researchers with information for analyses which compare or combine results of these and other studies and with materials for analysis by advanced molecular biology techniques. This Programmer's Guide document describes the database access software, NRADEMO, and the subset loading script NRADEMO/MAINT/MAINTAIN, which comprise the National Laboratory Archives Distributed Access Package. The guide is intended for use by an experienced database management specialist. It contains information about the physical and logical organization of the software and data files. It also contains printouts of all the scripts and associated batch processing files. It is part of a suite of documents published by the National Radiobiology Archives.

  8. Fast neutrons: Inexpensive and reliable tool to investigate high-LET particle radiobiology

    International Nuclear Information System (INIS)

    Gueulette, J.; Slabbert, J.P.; Bischoff, P.; Denis, J.M.; Wambersie, A.; Jones, D.

    2010-01-01

    Radiation therapy with carbon ions as well as missions into outer space have boosted the interest for high-LET particle radiobiology. Optimization of treatments in accordance with technical developments, as well as the radioprotection of cosmonauts during long missions require that research in these domains continue. Therefore suitable radiation fields are needed. Fast neutrons and carbon ions exhibit comparable LET values and similar radiobiological properties. Consequently, the findings obtained with each radiation quality could be shared to benefit knowledge in all concerned domains. The p(66+Be) neutron therapy facilities of iThemba LABS (South Africa) and the p(65)+Be neutron facility of Louvain-la-Neuve (Belgium) are in constant use to do radiobiological research for clinical applications with fast neutrons. These beams - which comply with all physical and technical requirements for clinical applications - are now fully reliable, easy to use and frequently accessible for radiobiological investigations. These facilities thus provide unique opportunities to undertake radiobiological experimentation, especially for investigations that require long irradiation times and/or fractionated treatments.

  9. Novel aspects of cellular action of dipeptidyl peptidase IV/CD26.

    Science.gov (United States)

    Ansorge, Siegfried; Nordhoff, Karsten; Bank, Ute; Heimburg, Anke; Julius, Heiko; Breyer, Doreen; Thielitz, Anja; Reinhold, Dirk; Täger, Michael

    2011-03-01

    The cellular dipeptidyl peptidase IV (DPIV, E.C.3.4.14.5, CD26) is a type II membrane peptidase with various physio-logical functions. Our main knowledge on DPIV comes from studies of soluble DPIV which plays a role in regulation of glucose homeostasis by inactivation of the incretins glucagon-like peptide-1 and glucose-dependent insulinotropic poly-peptide. It has been reported that membrane-bound DPIV plays a crucial role in the immune system and in other tissues and cells, but the knowledge on the action of cellular DPIV and its regulation is limited. In this study, we show particularly for immune cells that DPIV and not DP8 or DP9 is the most potent member of the DPIV family in regulating cellular immune functions. Moreover, we provide evidence that soluble and cellular DPIV differ in functions and hand-ling of substrates and inhibitors owing to the different accessibility of peptide substrates to the two access paths of DPIV. The different functions are based on the favored access path of the central pore of cellular DPIV and a special central pore binding site which assists substrate access to the active site of the enzyme. The newly discovered central pore binding site mediates an autosterical regulation of cellular DPIV and is its most crucial target site to regulate cellular functions such as growth and cytokine production. Neuropeptide Y (NPY) processing by cellular DPIV was found to be inhibited by ligands which interact with the central pore binding site. This finding suggests a crucial role of the immunosuppressive cytokine NPY in the function of DPIV in growth regulation.

  10. With the Radiobiology Group

    CERN Multimedia

    CERN PhotoLab

    1980-01-01

    The Radiobiology Group carries out experiments to study the effect of radiation on living cells. The photo shows the apparatus for growing broad beans which have been irradiated by 250 GeV protons. The roots are immersed in a tank of running water (CERN Weekly Bulletin 26 January 1981 and Annual Report 1980 p. 160). Karen Panman, Marilena Streit-Bianchi, Roger Paris.

  11. Novel Radiobiological Gamma Index for Evaluation of 3-Dimensional Predicted Dose Distribution

    Energy Technology Data Exchange (ETDEWEB)

    Sumida, Iori, E-mail: sumida@radonc.med.osaka-u.ac.jp [Department of Radiation Oncology, Osaka University Graduate School of Medicine, Osaka (Japan); Yamaguchi, Hajime; Kizaki, Hisao; Aboshi, Keiko; Tsujii, Mari; Yoshikawa, Nobuhiko; Yamada, Yuji [Department of Radiation Oncology, NTT West Osaka Hospital, Osaka (Japan); Suzuki, Osamu; Seo, Yuji [Department of Radiation Oncology, Osaka University Graduate School of Medicine, Osaka (Japan); Isohashi, Fumiaki [Department of Radiation Oncology, NTT West Osaka Hospital, Osaka (Japan); Yoshioka, Yasuo [Department of Radiation Oncology, Osaka University Graduate School of Medicine, Osaka (Japan); Ogawa, Kazuhiko [Department of Radiation Oncology, NTT West Osaka Hospital, Osaka (Japan)

    2015-07-15

    Purpose: To propose a gamma index-based dose evaluation index that integrates the radiobiological parameters of tumor control (TCP) and normal tissue complication probabilities (NTCP). Methods and Materials: Fifteen prostate and head and neck (H&N) cancer patients received intensity modulated radiation therapy. Before treatment, patient-specific quality assurance was conducted via beam-by-beam analysis, and beam-specific dose error distributions were generated. The predicted 3-dimensional (3D) dose distribution was calculated by back-projection of relative dose error distribution per beam. A 3D gamma analysis of different organs (prostate: clinical [CTV] and planned target volumes [PTV], rectum, bladder, femoral heads; H&N: gross tumor volume [GTV], CTV, spinal cord, brain stem, both parotids) was performed using predicted and planned dose distributions under 2%/2 mm tolerance and physical gamma passing rate was calculated. TCP and NTCP values were calculated for voxels with physical gamma indices (PGI) >1. We propose a new radiobiological gamma index (RGI) to quantify the radiobiological effects of TCP and NTCP and calculate radiobiological gamma passing rates. Results: The mean RGI gamma passing rates for prostate cases were significantly different compared with those of PGI (P<.03–.001). The mean RGI gamma passing rates for H&N cases (except for GTV) were significantly different compared with those of PGI (P<.001). Differences in gamma passing rates between PGI and RGI were due to dose differences between the planned and predicted dose distributions. Radiobiological gamma distribution was visualized to identify areas where the dose was radiobiologically important. Conclusions: RGI was proposed to integrate radiobiological effects into PGI. This index would assist physicians and medical physicists not only in physical evaluations of treatment delivery accuracy, but also in clinical evaluations of predicted dose distribution.

  12. Radiobiological research needed for the improvement of radiotherapy

    International Nuclear Information System (INIS)

    1977-01-01

    . Hyperthermia appears to be a promising way of treating various types of cancer either alone or in combination with radiation. Although the mechanisms of action of hyperthermia on tumour and normal cells is obscure at the moment, it has increased the radiation sensitivity of many types of tumours. Hyperthermia also increases cytotoxic effects of conventional chemotherapeutic agents and may therefore prove useful in combination with chemotherapy. The chemotherapy drugs extensively used in cancer treatment can be classified as alkylating agents, antimetabolites, mitotic inhibitors, anti-tumour antibiotics, and miscellaneous other chemicals whose mechanism of action has not been understood. Combination of radiation therapy with chemotherapy has proved to be the best mode of cancer treatment. During the discussions it became evident that radiation effects on cells are understood to a greater extent than are the effects of chemotherapeutic agents. It was therefore emphasized that more basic research ought to be done on the mechanism of action of chemotherapeutic drugs. Use of heavily ionizing radiations, such as neutrons, rr-mesons and stripped nuclei, has been advocated for treatment of certain tumours. Intensive research is underway on the effects of such radiations in the USA, Canada and Western Europe. In a panel discussion on future radiobiological research needs for radiotherapy, it was pointed out that radiobiologists and radiotherapists have so far worked on different platforms. Whereas the radiotherapist has been overburdened with treatment of patients, radiobiologists have mainly concentrated their efforts on in vitro systems which may or may not be of use in patient treatment. It was therefore emphasized that radiotherapy clinics must have consultant radiobiologists, and that radiobiologists ought to be familiar with the clinical problems in hospitals. In the UK and USA such arrangements have been mutually profitable. (author)

  13. New challenges in high-energy particle radiobiology

    Science.gov (United States)

    2014-01-01

    Densely ionizing radiation has always been a main topic in radiobiology. In fact, α-particles and neutrons are sources of radiation exposure for the general population and workers in nuclear power plants. More recently, high-energy protons and heavy ions attracted a large interest for two applications: hadrontherapy in oncology and space radiation protection in manned space missions. For many years, studies concentrated on measurements of the relative biological effectiveness (RBE) of the energetic particles for different end points, especially cell killing (for radiotherapy) and carcinogenesis (for late effects). Although more recently, it has been shown that densely ionizing radiation elicits signalling pathways quite distinct from those involved in the cell and tissue response to photons. The response of the microenvironment to charged particles is therefore under scrutiny, and both the damage in the target and non-target tissues are relevant. The role of individual susceptibility in therapy and risk is obviously a major topic in radiation research in general, and for ion radiobiology as well. Particle radiobiology is therefore now entering into a new phase, where beyond RBE, the tissue response is considered. These results may open new applications for both cancer therapy and protection in deep space. PMID:24198199

  14. (RadioBiological Optimization of External-Beam Radiotherapy

    Directory of Open Access Journals (Sweden)

    Alan E. Nahum

    2012-01-01

    Full Text Available “Biological optimization” (BIOP means planning treatments using (radiobiological criteria and models, that is, tumour control probability and normal-tissue complication probability. Four different levels of BIOP are identified: Level I is “isotoxic” individualization of prescription dose at fixed fraction number. is varied to keep the NTCP of the organ at risk constant. Significant improvements in local control are expected for non-small-cell lung tumours. Level II involves the determination of an individualized isotoxic combination of and fractionation scheme. This approach is appropriate for “parallel” OARs (lung, parotids. Examples are given using our BioSuite software. Hypofractionated SABR for early-stage NSCLC is effectively Level-II BIOP. Level-III BIOP uses radiobiological functions as part of the inverse planning of IMRT, for example, maximizing TCP whilst not exceeding a given NTCP. This results in non-uniform target doses. The NTCP model parameters (reflecting tissue “architecture” drive the optimizer to emphasize different regions of the DVH, for example, penalising high doses for quasi-serial OARs such as rectum. Level-IV BIOP adds functional imaging information, for example, hypoxia or clonogen location, to Level III; examples are given of our prostate “dose painting” protocol, BioProp. The limitations of and uncertainties inherent in the radiobiological models are emphasized.

  15. A model to describe potential effects of chemotherapy on critical radiobiological treatments

    Science.gov (United States)

    Rodríguez-Pérez, D.; Desco, M. M.; Antoranz, J. C.

    2016-08-01

    Although chemo- and radiotherapy can annihilate tumors on their own. they are also used in coadjuvancy: improving local effects of radiotherapy using chemotherapy as a radiosensit.izer. The effects of radiotherapy are well described by current radiobiological models. The goal of this work is to describe a discrete radiotherapy model, that has been previously used describe high radiation dose response as well as unusual radio-responses of some types of tumors (e.g. prostate cancer), to obtain a model of chemo+radiotherapy that can describe how the outcome of their combination is a more efficient removal of the tumor. Our hypothesis is that, although both treatments haven different mechanisms, both affect similar key points of cell metabolism and regulation, that lead to cellular death. Hence, we will consider a discrete model where chemotherapy may affect a fraction of the same targets destroyed by radiotherapy. Although radiotherapy reaches all cells equally, chemotherapy diffuses through a tumor attaining lower concentration in its center and higher in its surface. With our simulations we study the enhanced effect of combined therapy treatment and how it depends on the tissue critical parameters (the parameters of the lion-extensive radiobiological model), the number of “targets” aimed at by chemotherapy, and the concentration and diffusion rate of the drug inside the tumor. The results show that an equivalent, cliemo-radio-dose can be computed that allows the prediction of the lower radiation dose that causes the same effect than a radio-only treatment.

  16. Radiobiology, biochemistry and radiation biophysics at CYLAB

    International Nuclear Information System (INIS)

    Ftacnikova, S.

    1998-01-01

    The Cyclotron Laboratory (CYLAB) should fill the gap in the field of nuclear medicine, radiotherapy, basic research, metrology of ionizing radiation, education and implications of accelerator technology existing today in Slovak Republic. The main planned activities of this facility are in the fields of nuclear medicine (production of radioisotopes for Positron Emission Tomography - PET and for oncology) and radiotherapy (neutron capture therapy, fast neutron therapy and proton therapy). The radiobiological and biophysical research will be closely connected with medical applications, particularly with radiotherapy. Problems to be addressed include the determination of the values of Relative Biological Effectiveness (RBE) for different types of ionizing radiation involved in the therapy, microdosimetric measurements and calculations, which are indispensable in the calculation of the absorbed dose (lineal and specific energy spectra) at the cellular and macromolecular level. Radiation biophysics and medical physics help in creating therapeutic plans for radiotherapy (NCT and fast neutron therapy). In nuclear medicine, in diagnostic and therapeutical procedures it is necessary to assess the biodistribution of radiopharmaceuticals and to calculate doses in target and critical organs and to determine whole body burden - effective equivalent dose for newly developed radiopharmaceuticals

  17. Investigations of DNA damage induction and repair resulting from cellular exposure to high dose-rate pulsed proton beams

    International Nuclear Information System (INIS)

    Renis, M.; Malfa, G.; Tomasello, B.; Borghesi, M.; Schettino, G.; Favetta, M.; Romano, F.; Cirrone, G. A. P.; Manti, L.

    2013-01-01

    Studies regarding the radiobiological effects of low dose radiation, microbeam irradiation services have been developed in the world and today laser acceleration of protons and heavy ions may be used in radiation therapy. The application of different facilities is essential for studying bystander effects and relating signalling phenomena in different cells or tissues. In particular the use of ion beams results advantageous in cancer radiotherapy compared to more commonly used X-rays, since the ability of ions in delivering lethal amount of doses into the target tumour avoiding or limiting damage to the contiguous healthy tissues. At the INFN-LNS in Catania, a multidisciplinary radiobiology group is strategically structured aimed to develop radiobiological research, finalised to therapeutic applications, compatible with the use of high dose laser-driven ion beams. The characteristic non-continuous dose rates with several orders of magnitude of laser-driven ion beams makes this facility very interesting in the cellular systems' response to ultra-high dose rates with non-conventional pulse time intervals cellular studies. Our group have projected to examine the effect of high dose laser-driven ion beams on two cellular types: foetal fibroblasts (normal control cells) and DU145 (prostate cancer cells), studying the modulation of some different bio-molecular parameters, in particular cell proliferation and viability, DNA damage, redox cellular status, morphological alterations of both the cytoskeleton components and some cell organelles and the possible presence of apoptotic or necrotic cell death. Our group performed preliminary experiments with high energy (60 MeV), dose rate of 10 Gy/min, doses of 1, 2, 3 Gy and LET 1 keV/μm on human foetal fibroblasts (control cells). We observed that cell viability was not influenced by the characteristics of the beam, the irradiation conditions or the analysis time. Conversely, DNA damage was present at time 0, immediately

  18. Investigations of DNA damage induction and repair resulting from cellular exposure to high dose-rate pulsed proton beams

    Energy Technology Data Exchange (ETDEWEB)

    Renis, M.; Malfa, G.; Tomasello, B. [Drug Sciences Department, University of Catania, Catania (Italy); Borghesi, M.; Schettino, G. [Queen' s University Belfast, Northern Ireland (United Kingdom); Favetta, M.; Romano, F.; Cirrone, G. A. P. [National Institute for Nuclear Physics (INFN-LNS), Catania (Italy); Manti, L. [Physics Science Department, University of Naples Federico II, Naples, and National Institute for Nuclear Physics (INFN), Naples (Italy)

    2013-07-26

    Studies regarding the radiobiological effects of low dose radiation, microbeam irradiation services have been developed in the world and today laser acceleration of protons and heavy ions may be used in radiation therapy. The application of different facilities is essential for studying bystander effects and relating signalling phenomena in different cells or tissues. In particular the use of ion beams results advantageous in cancer radiotherapy compared to more commonly used X-rays, since the ability of ions in delivering lethal amount of doses into the target tumour avoiding or limiting damage to the contiguous healthy tissues. At the INFN-LNS in Catania, a multidisciplinary radiobiology group is strategically structured aimed to develop radiobiological research, finalised to therapeutic applications, compatible with the use of high dose laser-driven ion beams. The characteristic non-continuous dose rates with several orders of magnitude of laser-driven ion beams makes this facility very interesting in the cellular systems' response to ultra-high dose rates with non-conventional pulse time intervals cellular studies. Our group have projected to examine the effect of high dose laser-driven ion beams on two cellular types: foetal fibroblasts (normal control cells) and DU145 (prostate cancer cells), studying the modulation of some different bio-molecular parameters, in particular cell proliferation and viability, DNA damage, redox cellular status, morphological alterations of both the cytoskeleton components and some cell organelles and the possible presence of apoptotic or necrotic cell death. Our group performed preliminary experiments with high energy (60 MeV), dose rate of 10 Gy/min, doses of 1, 2, 3 Gy and LET 1 keV/μm on human foetal fibroblasts (control cells). We observed that cell viability was not influenced by the characteristics of the beam, the irradiation conditions or the analysis time. Conversely, DNA damage was present at time 0, immediately

  19. Thresholds in radiobiology

    International Nuclear Information System (INIS)

    Katz, R.; Hofmann, W.

    1982-01-01

    Interpretations of biological radiation effects frequently use the word 'threshold'. The meaning of this word is explored together with its relationship to the fundamental character of radiation effects and to the question of perception. It is emphasised that although the existence of either a dose or an LET threshold can never be settled by experimental radiobiological investigations, it may be argued on fundamental statistical grounds that for all statistical processes, and especially where the number of observed events is small, the concept of a threshold is logically invalid. (U.K.)

  20. Workshop on radiobiological effectiveness of neutrons

    International Nuclear Information System (INIS)

    Stapleton, G.E.; Thomas, R.G.; Thiessen, J.W.

    1985-09-01

    The radiobiological effectiveness (RBE) of neutrons has become the subject of some heated discussions in both scientific and radiation-protection oriented communities. This has become especially so since the realization that neutron exposures of A-bomb survivors in Hiroshima were considerably lower than previously assumed, thus ''devaluating'' the importance of what we thought was a solid human data base. At the same time, more recent data from radiobiological research appeared to indicate that, at least for some biological endpoints, the RBE of neutrons at low doses and low dose rates was increased dramatically compared to the RBE at higher dose and dose rates. As a consequence, the protection of health against neutrons became a subject of some urgency. The objective of this workshop was to evaluate the existing data base in order to determine the need for additional research in this field. 22 refs., 3 figs., 6 tabs

  1. Item 141 Radiotherapy. Radiobiological notions; main secondary effects

    International Nuclear Information System (INIS)

    Azria, David; Dubois, Jean-Bernard

    2006-11-01

    This document first gives definitions of ionizing radiations, photons, electrons and Gray (as a dose unit). It describes the mechanisms of action of ionizing radiations: physical, chemical, cellular actions, actions on tissues. It analyses and discusses the factors influencing the effects of radiations: intrinsic radio-sensitivity, cellular cycle, oxygen, time (session fractioning and organisation in time), and dose. The different types of radiotherapy are then presented: external radiotherapy, brachytherapy, radio-immunotherapy of internal radiotherapy. It discusses tissues tolerance doses and doses required to sterilize tumours, and discusses the various and main secondary effects: stochastic secondary effects and deterministic secondary effects. A table indicates possible early and late reactions for different organs (skin, lung, brain, medulla, nerves, oesophagus, heart, pancreas, stomach, liver, intestine, kidney, bladder, rectum, ENT, or eye's lens)

  2. Recent radiobiological findings from spaceflight and ground-based studies - an overview

    Energy Technology Data Exchange (ETDEWEB)

    Buecker, H.; Facius, R.

    1980-01-01

    An a priori risk assessment of radiobiological effects remains uncertain due to the unpredictable solar flare contribution to the low LET radiation or the unknown reaction mechanisms of heavy ions. Tests suggest that mechanisms inherent to biological systems may be impeded by physiological and psychological stress during spaceflight. The discovery of heavy ion induced late effects in rabbits demonstrates what might be experienced during longer space missions. The evidence for a specific radiobiological reaction mechanism of heavy ions as encountered in space is discussed. A report by Kovalev and Markelov (1979) on LET spectra is reviewed, and the use of absorbed dose as the quantity of reference in estimating an average radiobiological quality factor representative of cosmic particle radiation is criticized.

  3. Radiobiological comparison of pions and heavy ions

    International Nuclear Information System (INIS)

    Raju, M.R.

    1981-01-01

    The physical and radiobiological differences between some aspects of pions and heavy ions are discussed, followed by a discussion of acute and late effects of high LET radiations compared to low LET radiations

  4. WE-DE-202-02: Are Track Structure Simulations Truly Needed for Radiobiology at the Cellular and Tissue Levels?

    International Nuclear Information System (INIS)

    Stewart, R.

    2016-01-01

    processes are too complex for a mechanistic approach. Can computer simulations be used to guide future biological research? We will debate the feasibility of explaining biology from a physicists’ perspective. Learning Objectives: Understand the potential applications and limitations of computational methods for dose-response modeling at the molecular, cellular and tissue levels Learn about mechanism of action underlying the induction, repair and biological processing of damage to DNA and other constituents Understand how effects and processes at one biological scale impact on biological processes and outcomes on other scales J. Schuemann, NCI/NIH grantsS. McMahon, Funding: European Commission FP7 (grant EC FP7 MC-IOF-623630)

  5. WE-DE-202-02: Are Track Structure Simulations Truly Needed for Radiobiology at the Cellular and Tissue Levels?

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, R. [University of Washington (United States)

    2016-06-15

    processes are too complex for a mechanistic approach. Can computer simulations be used to guide future biological research? We will debate the feasibility of explaining biology from a physicists’ perspective. Learning Objectives: Understand the potential applications and limitations of computational methods for dose-response modeling at the molecular, cellular and tissue levels Learn about mechanism of action underlying the induction, repair and biological processing of damage to DNA and other constituents Understand how effects and processes at one biological scale impact on biological processes and outcomes on other scales J. Schuemann, NCI/NIH grantsS. McMahon, Funding: European Commission FP7 (grant EC FP7 MC-IOF-623630)

  6. A radiobiological review on melatonin. A novel radioprotector

    International Nuclear Information System (INIS)

    Shirazi, A.; Ghobadi, G.; Ghazi-Khansari, M.

    2007-01-01

    In spite of the fact that radiotherapy is a common and effective tool for cancer treatment; the radio sensitivity of normal tissues adjacent to the tumor which are unavoidably exposed to radiation limits therapeutic gain. For the sake of improvement in radiation therapy, radiobiology- the study of the action of ionizing radiation on living things- plays a crucial role through explaining observed phenomena, and suggesting improvements to existing therapies. Due to the damaging effects of ionizing radiation, radiobiologists have long been interested in identifying novel, nontoxic, effective, and convenient compounds to protect humans against radiation induced normal tissue injuries. In hundreds of investigations, melatonin (N-acetyl-5-methoxytryptamine), the chief secretory product of the pineal gland in the brain, has been documented to ameliorate the oxidative injuries due to ionizing radiation. This article reviews different features that make melatonin a potentially useful radioprotector. Moreover, based on radiobiological models we can hypothesize that melatonin may postpone the saturation of repair enzymes which leads to repairing more induced damage by repair system and more importantly allows the use of higher doses of radiation during radiotherapy to get a better therapeutic ratio. The implications of the accumulated observations suggest by virtue of melatonin's radioprotective and anticancer effects; it is time to use it as a radioprotector both for radiation workers and patients suffering from cancer either alone for cancer inhibition or in combination with traditional radiotherapy for getting a favorable efficacy/toxicity ratio during the treatment. Although compelling evidence suggests that melatonin may be effective for a variety of disorders, the optimum dose of melatonin for human radioprotection is yet to be determined. We propose that, in the future, melatonin improve the therapeutic ratio in radiation oncology. (author)

  7. Cellular radiosensitivity of small-cell lung cancer cell lines

    International Nuclear Information System (INIS)

    Krarup, Marianne; Poulsen, Hans Skovgaard; Spang-Thomsen, Mogens

    1997-01-01

    Purpose: The objective of this study was to determine the radiobiological characteristics of a panel of small-cell lung cancer (SCLC) cell lines by use of a clonogenic assay. In addition, we tested whether comparable results could be obtained by employing a growth extrapolation method based on the construction of continuous exponential growth curves. Methods and Materials: Fifteen SCLC cell lines were studied, applying a slightly modified clonogenic assay and a growth extrapolation method. A dose-survival curve was obtained for each experiment and used for calculating several survival parameters. The multitarget single hit model was applied to calculate the cellular radiosensitivity (D 0 ), the capacity for sublethal damage repair (D q ), and the extrapolation number (n). Values for α and β were determined from best-fit curves according to the linear-quadratic model and these values were applied to calculate the surviving fraction after 2-Gy irradiation (SF 2 ). Results: In our investigation, the extrapolation method proved to be inappropriate for the study of in vitro cellular radiosensitivity due to lack of reproducibility. The results obtained by the clonogenic assay showed that the cell lines studied were radiobiologically heterogeneous with no discrete features of the examined parameters including the repair capacity. Conclusion: The results indicate that SCLC tumors per se are not generally candidates for hyperfractionated radiotherapy

  8. Radiobiology of systemic radiation therapy.

    Science.gov (United States)

    Murray, David; McEwan, Alexander J

    2007-02-01

    Although systemic radionuclide therapy (SRT) is effective as a palliative therapy in patients with metastatic cancer, there has been limited success in expanding patterns of utilization and in bringing novel systemic radiotherapeutic agents to routine clinical use. Although there are many factors that contribute to this situation, we hypothesize that a better understanding of the radiobiology and mechanism of action of SRT will facilitate the development of future compounds and the future designs of prospective clinical trials. If these trials can be rationalized to the biological basis of the therapy, it is likely that the long-term outcome would be enhanced therapeutic efficacy. In this review, we provide perspectives of the current state of low-dose-rate (LDR) radiation research and offer linkages where appropriate with current clinical knowledge. These include the recently described phenomena of low-dose hyper-radiosensitivity-increased radioresistance (LDH-IRR), adaptive responses, and biological bystander effects. Each of these areas require a major reconsideration of existing models for radiation action and an understanding of how this knowledge will integrate into the evolution of clinical SRT practice. Validation of a role in vivo for both LDH-IRR and biological bystander effects in SRT would greatly impact the way we would assess therapeutic response to SRT, the design of clinical trials of novel SRT radiopharmaceuticals, and risk estimates for both therapeutic and diagnostic radiopharmaceuticals. We believe that the current state of research in LDR effects offers a major opportunity to the nuclear medicine community to address the basic science of clinical SRT practice, to use this new knowledge to expand the use and roles of SRT, and to facilitate the introduction of new therapeutic radiopharmaceuticals.

  9. Optimization in brachytherapy with the implementation of Radiobiology

    International Nuclear Information System (INIS)

    Duran, M.P.; Bourel, V.J.; Rodriguez, I.; Torre, M. de la; Caneva, S.

    1998-01-01

    In the brachytherapy planning treatments with High dose rates (HDR), the optimization algorithms used are based in dosimetric considerations and/or geometric ones, ignoring the radiobiological response of the tissue treated. In this work we wish to show the implementation of radiobiological concepts in the optimization. Assuming that the subtiles differences that result in the dose distribution among the different optimization models which are not visible in an isodose plane, it is studied how is classically make it , the quality implant through natural histograms about dose volumes and the resulting parameters. Also is studied the necrosis probability which may be caused by the choice of some optimization model, allowing with this the choice of the best implant. (Author)

  10. Molecular biology - Part II: Beneficial liaisons: Radiobiology meets cellular and molecular biology

    International Nuclear Information System (INIS)

    Stevenson, Mary Ann; Coleman, C. Norman

    1997-01-01

    Purpose: The purpose of this course is to familiarize radiation oncologists with the concepts and terminology of molecular and cellular biology that are especially relevant to radiation oncology. The ability of radiation oncologists to remain current with the new discoveries of modern biology is essential to the development of improved therapeutic strategies and, importantly, to the proper balance between investment in technology and biology. Objective: This year, this Refresher Course is part of a three-part ''series'' including Drs. McKenna and Dritschilo. The objective is to provide continuing education for the academic and practicing radiation oncologist, physicist and biologist in the modern biologic concepts of cancer and its treatment. An effort will be made to relate these general concepts to the clinic by providing a broad view as to potential new biological treatments which might enhance the efficacy of radiation therapy. The specific focus of this Course will vary from year to year. Some of the classic radiation biology models which form the basis of clinical practice and laboratory research will be examined and 'newer' models will be presented which take into account the emerging knowledge of cellular and molecular biology. A few techniques in molecular and cellular biology will be described to the extent necessary to understand their basic concepts and their applicability. Aspects of radiation biology which will be covered include cell cycle, radiation-induced changes in the cellular phenotype, and considerations of the effect of the tumor microenvironment. It is not the expectation that the attendees will become experts in the particular subjects presented. Rather, it is the intent to increase their curiosity as to the new knowledge that is emerging and to demonstrate that these seemingly complicated areas can be understood and appreciated with a modicum of the effort

  11. Molecular biology - Part II: Beneficial liaisons: Radiobiology meets cellular and molecular biology

    International Nuclear Information System (INIS)

    Stevenson, Mary Ann; Coleman, C. Norman

    1996-01-01

    Purpose: The purpose of this course is to familiarize radiation oncologists with the concepts and terminology of molecular and cellular biology that are especially relevant to radiation oncology. The ability of radiation oncologists to remain current with the new discoveries of modern biology is essential to the development of improved therapeutic strategies and, importantly, to the proper balance between investment in technology and biology. Objective: This year, this Refresher Course is part of a three-part 'series' including Drs. Martin Brown and Amato Giaccia. The objective is to provide continuing education for the academic and practicing radiation oncologist, physicist and biologist in the modern biologic concepts of cancer and its treatment. An effort will be made to relate these general concepts to the clinic by providing a broad view as to potential new biological treatments which might enhance the efficacy of radiation therapy. The specific focus of this Course will vary from year to year. Some of the classic radiation biology models which form the basis of clinical practice and laboratory research will be examined and 'newer' models will be presented which take into account the emerging knowledge of cellular and molecular biology. A few techniques in molecular and cellular biology will be described to the extent necessary to understand their basic concepts and their applicability. Aspects of radiation biology which will be covered include cell cycle, radiation-induced changes in the cellular phenotype, and considerations of the effect of the tumor microenvironment. It is not the expectation that the attendees will become experts in the particular subjects presented. Rather, it is the intent to increase their curiosity as to the new knowledge that is emerging and to demonstrate that these seemingly complicated areas can be understood and appreciated with a modicum of the effort

  12. Soft x rays for radiobiological studies

    International Nuclear Information System (INIS)

    Ban, Sadayuki; Iida, Shozo; Shimba, Hachiro; Awa, A.A.; Hamilton, H.B.; Clifton, K.H.

    1986-04-01

    Lethal effects and chromosome aberrations induced in cells exposed to low energy (soft) X rays demonstrated that these relatively low energy X rays are just as effective as those of higher energy for radiobiological studies, and even more effective for irradiating cultured mammalian cells than laboratory animals. (author)

  13. Radiobiological basis of radiation protection and ICRP 2007 general recommendations

    International Nuclear Information System (INIS)

    Rao, B.S.

    2014-01-01

    The ICRP 2007 General Recommendations are based on the detailed review of the new information on the biological effects and risk evaluation done during the last decade. Most of this information reinforces the validity of earlier findings. Since the publication of ICRP 60 general recommendations in 1991(ICRP 1991b), sufficient new information on the health effects of ionizing radiations has accrued based on radiobiological and epidemiological studies (UNSCEAR 2000, ICRP Publication 99). There is an improvement in understanding the mechanistic aspects of the induction of radiation damage at cellular level. Biophysical studies based on Monte Carlo track structure codes have provided information on the nature of critical damage to DNA leading to the radiation effects at cellular level. Experimental work with model animal systems has provided information on the role of post irradiation repair processes and the genes influencing the process of radiation carcinogenesis. Longer follow up of A-Bomb survivors of Hiroshima and Nagasaki now provides a more reliable risk estimate based on the cancer incidence data and also a better model for the transfer of risk among different populations with varying frequency of background incidence. At present it is clear that the breast cancer contributes substantially to the radiation risk and provides quantitative risk estimates for brain and salivary glands. In the light of the new information, Tissue Weighting factors (WT) have been revised

  14. A model to describe potential effects of chemotherapy on critical radiobiological treatments

    International Nuclear Information System (INIS)

    Rodríguez-Pérez, D.; Desco, M.M.; Antoranz, J.C.

    2016-01-01

    Although chemo- and radiotherapy can annihilate tumors on their own. they are also used in coadjuvancy: improving local effects of radiotherapy using chemotherapy as a radiosensit.izer. The effects of radiotherapy are well described by current radiobiological models. The goal of this work is to describe a discrete radiotherapy model, that has been previously used describe high radiation dose response as well as unusual radio-responses of some types of tumors (e.g. prostate cancer), to obtain a model of chemo+radiotherapy that can describe how the outcome of their combination is a more efficient removal of the tumor. Our hypothesis is that, although both treatments haven different mechanisms, both affect similar key points of cell metabolism and regulation, that lead to cellular death. Hence, we will consider a discrete model where chemotherapy may affect a fraction of the same targets destroyed by radiotherapy. Although radiotherapy reaches all cells equally, chemotherapy diffuses through a tumor attaining lower concentration in its center and higher in its surface. With our simulations we study the enhanced effect of combined therapy treatment and how it depends on the tissue critical parameters (the parameters of the lion-extensive radiobiological model), the number of “targets” aimed at by chemotherapy, and the concentration and diffusion rate of the drug inside the tumor. The results show that an equivalent, cliemo-radio-dose can be computed that allows the prediction of the lower radiation dose that causes the same effect than a radio-only treatment. (paper)

  15. Heavy-ion radiobiology: new approaches to delineate mechanisms underlying enhanced biological effectiveness

    Science.gov (United States)

    Blakely, E. A.; Kronenberg, A.; Chatterjee, A. (Principal Investigator)

    1998-01-01

    Shortly after the discovery of polonium and radium by Marie Curie and her husband and colleague, Pierre Curie, it was learned that exposure to these alpha-particle emitters produced deleterious biological effects. The mechanisms underlying the increased biological effectiveness of densely ionizing radiations, including alpha particles, neutrons and highly energetic heavy charged particles, remain an active area of investigation. In this paper, we review recent advances in several areas of the radiobiology of these densely ionizing radiations, also known as heavy ions. Advances are described in the areas of DNA damage and repair, chromosome aberrations, mutagenesis, neoplastic transformation in vitro, genomic instability, normal tissue radiobiology and carcinogenesis in vivo. We focus on technical innovations, including novel applications of pulsed-field gel electrophoresis, fluorescence in situ hybridization (FISH), linkage analysis, and studies of gene expression and protein expression. We also highlight the use of new cellular and animal systems, including those with defined DNA repair deficiencies, as well as epithelial cell model systems to assess neoplastic transformation both in vitro and in vivo. The studies reviewed herein have had a substantial impact on our understanding of the genotoxic effects of heavy ions as well as their distinct effects on tissue homeostasis. The use of these radiations in cancer therapy is also discussed. The use of both heavy-ion and proton therapy is on the upswing in several centers around the world, due to their unique energy deposition characteristics that enhance the therapeutic effect and help reduce damage to normal tissue.

  16. Radiobiological research for improving tumor radiotherapy - an Indian perspective

    International Nuclear Information System (INIS)

    Jain, Viney

    1990-01-01

    Radiation-induced damage to normal tissues within the non-target volume is a major limitation of tumor radiotherapy. Physical methods to obtain superior spatial dose distributions use sophisticated technology and are expensive. Large scale applications of these technologies in a developing country like India, with a large number of cancer patients, poor instrumental facilities and inadequate infrastructure face several problems. Radiobiological research aiming at developing simple, inexpensive and effective methods to increase the differential response between tumor and normal tissues should be, therefore, strengthened. Biological end-points are determined not only by the molecular lesions produced due to the absorption of the radiation energy but also by the cellular repair processes, which become operative in response to lesions in the living system. Therefore, enhancement of repair processes in the normal tissues and inhibition of the same in tumors should considerably improve the therapeutic index of radiation treatment. A combination of agents which can suitably alter the spectrum of important molecular lesions with modifiers of cellular repair could be an effective strategy. Initial experiments using halopyrimidines to increase repairable DNA lesions produced by sparsely ionizing radiations in combination with 2-deoxy-D-glucose to modulate differentially the repair and fixation processes in the tumor and normal tissues have provided promising results. Further research work is warranted since this strategy appears to have great potential for improving tumor radiotherapy. (author). 46 refs., 4 figs., 1 tab

  17. Press breakfast, radiobiology stakes: an European context, Thursday 25 March 2004

    International Nuclear Information System (INIS)

    2004-03-01

    The radiobiology endeavours to know the ionizing radiations effects on living systems, particular at low doses exposures. The researches in this area contribute to the elaboration of international regulation on nuclear industry. The individual radiosensitivity is an other aspect of the research in radiobiology. These studies should allow the establishing of radiation protection standards founded on a direct approach and an individual estimation of the level of acceptable dose. (N.C.)

  18. Advances and perspectives in radiobiological technology

    International Nuclear Information System (INIS)

    Kuzin, A.M.; Kaushanskij, D.A.

    1983-01-01

    On the basis of the analysis of experience in the USSR and in foreign countries nowadays the state and perspectives for the development of a new, in principle, aspect of technology is considered based on using ionizing radiations and radiobiological effects in agriculture, medical-, food-, microbiological and other branches of industry

  19. Recommendations for the future of translational radiobiology research: a Canadian perspective

    International Nuclear Information System (INIS)

    Bristow, Robert G.

    2004-01-01

    The use of molecular medicine is now merging into clinical practice with the advent of molecular targeting agents, molecular pathology and molecular imaging for both diagnosis and treatment response. Radiation oncologists must therefore gain expertise in utilizing this information to drive new treatment protocols. Recognizing the importance of this issue, the Canadian Association of Radiation Oncologists (CARO) charged a Task Force in Translational Radiobiology to: (1) critically assess training programs and research infrastructure in relation to current and future translational radiobiology requirements; and (2) make specific recommendations to accelerate the implementation of translational science into day-to-day practice. Selected Task Force recommendations included the principle that universities and departmental Chairs increase the opportunities for academic promotion, funding, and tenure track positions of radiobiologists and translational radiation oncologists. The dedication of 4 to 5 national centers as translational 'hubs', can serve as an interface between clinicians, clinical specimens and radiobiological sciences within the context of correlative clinical trials. The model of the clinician-scientist was encouraged as an important adjunct to good clinical care to be associated with strong enticement, training and mentoring programs and 75%-protected research time. Finally, an integrated model of radiobiological training programs and mutual continuing education between clinicians and basic scientists can be facilitated through a new national radiobiology meeting sponsored by CARO. These recommendations have been accepted by the national radiation oncology membership. Such a framework may serve useful for national programs wishing to develop rapid conduits from the lab to the clinic as a means of integrating molecular biology and the day-to-day practice of radiation oncology

  20. IAEA advisory group meeting on nuclear and atomic data for radiotherapy and related radiobiology in co-operation with the Radiobiological Institute of the Division for Health Research TNO, 16-20 September 1985, Rijswijk, the Netherlands

    International Nuclear Information System (INIS)

    Okamoto, K.

    1985-11-01

    The IAEA Advisory Group Meeting on ''Nuclear and Atomic Data for Radiotherapy and Related Radiobiology'' was held at Rijswijk, the Netherlands, from 16 to 20 September 1985, in co-operation with the Radiobiological Institute TNO. The meeting participants reviewed the current and future requirements on nuclear and atomic data for radiotherapy and radiobiology, identified data requirements and their priorities, and issued a number of specific recommendations for future technical work in nuclear and atomic data required to establish a more solid nuclear physics foundation of radiotherapy and related radiobiology. The recommendations in this report are directed to three areas, namely beam production and field description, dosimetry, and interpretation and optimization of biological effects. The final proceedings will be issued as an IAEA publication in 1986. (author)

  1. Small dose multi-fractionation therapy, its radiobiological aspects and clinics

    International Nuclear Information System (INIS)

    Iwai, Hiroshi; Katagiri, Shiro; Furuhata, Akihiko; Fukusi, Itsuhisa

    1979-01-01

    Recent radiobiological data reveal that cell killings by small dose fractionation are almost due to nonrepairable damage with low oxygen enhancement ratio. Then, Small dose multi-fractionation method suggests a higher therapeutic-ratio than that in conventional high dose fractionated irradiation. Using these data of radiobiology, intermittent irradiations three times a day, four hours interval, with 60 - 80 rads for multi-fractionation, with high total doses of 7,200 - 7,500 rads/6.5 - 7 weeks mainly on bladder, laryngeal and esophageal tumour are applied. The results obtained are slightly improved. (author)

  2. Influence of physical and biological factors in cellular radiosensitivity

    International Nuclear Information System (INIS)

    García Lima, Omar

    2016-01-01

    The use of therapeutic radiopharmaceuticals is associated with radiation damage, and this at-nuclear physical properties of radionuclides used and the characteristics of the irradiated cells. The work deals with the damage caused by radiation to DNA, factors that condition and tools that can be used to measure it. It presents current concepts of death and cellular radiosensitivity, based on the pioneering work in this field. Enter the neighborhood effect and adaptive response and evaluates the influence of the same in the paradigms of classical radiobiology. (author)

  3. The significance of the choice of radiobiological (NTCP) models in treatment plan objective functions

    International Nuclear Information System (INIS)

    Miller, J.; Fuller, M.; Vinod, S.; Holloway, L.

    2009-01-01

    Full text: A Clinician's discrimination between radiation therapy treatment plans is traditionally a subjective process, based on experience and existing protocols. A more objective and quantitative approach to distinguish between treatment plans is to use radiobiological or dosimetric objective functions, based on radiobiological or dosimetric models. The efficacy of models is not well understood, nor is the correlation of the rank of plans resulting from the use of models compared to the traditional subjective approach. One such radiobiological model is the Normal Tissue Complication Probability (NTCP). Dosimetric models or indicators are more accepted in clinical practice. In this study, three radiobiological models, Lyman NTCP, critical volume NTCP and relative seriality NTCP, and three dosimetric models, Mean Lung Dose (MLD) and the Lung volumes irradiated at lOGy (V|0) and 20 G y (V20), were used to rank a series of treatment plans using, harm to normal (Lung) tissue as the objective criterion. None of the models considered in this study showed consistent correlation with the Radiation Oncologists plan ranking. If radiobiological or dosimetric models are to be used in objective functions for lung treatments, based on this study it is recommended that the Lyman NTCP model be used because it will provide most consistency with traditional clinician ranking.

  4. Radiobiology of heavy charged particles

    International Nuclear Information System (INIS)

    Kraft, G.

    1996-11-01

    The increase in the biological efficiency is the major motivation to use ions heavier than protons for therapy. Therefore, the detailed understanding of the radiobiological potential of heavy ions like carbon or oxygen is the basic condition of a proper application of these ions in therapy. But also for the lightest ion, the proton, evidence accumulates that changes in the radiobiological properties at the end of the particle range influence the therapeutic effect. Compared to sparsely ionizing radiation heavy charged particles exhibit a different physical interaction with the target material: The highly charged ions interact mostly via Coulomb forces with the electrons of the target material producing a track of ionizations and highly kinetic electrons along the path of the primary ion. In these tracks damage to the biological structures like the DNA occurs in a non stochastic, but spatially correlated way yielding a dramatic variation in the biological severity of the created damage. In cell-experiments the variation in the relative biological efficiency has been measured for many biological reactions like cell inactivation, chromosome aberrations and DNA damage. An overview on the inactivation data will be given and theoretical approaches will be discussed and compared to experimental data. (orig.)

  5. Radiobiology with heavy charged particles: a historical review

    International Nuclear Information System (INIS)

    Skarsgard, L.D.

    1997-01-01

    The presentation will attempt to briefly review some of radiobiological data on the effects of heavy charged particles and to discuss the influence of those studies on the clinical application which followed. (orig./MG)

  6. A systemic approach to modelling of radiobiological effects

    International Nuclear Information System (INIS)

    Obaturov, G.M.

    1988-01-01

    Basic principles of the systemic approach to modelling of the radiobiological effects at different levels of cell organization have been formulated. The methodology is proposed for theoretical modelling of the effects at these levels

  7. Radiobiology with heavy charged particles: a historical review

    Energy Technology Data Exchange (ETDEWEB)

    Skarsgard, L D [Dept. of Medical Biophysics, B.C. Cancer Research Centre and TRIUMF, Vancouver (Canada)

    1997-09-01

    The presentation will attempt to briefly review some of radiobiological data on the effects of heavy charged particles and to discuss the influence of those studies on the clinical application which followed. (orig./MG)

  8. Radiobiological Impact of Planning Techniques for Prostate Cancer ...

    African Journals Online (AJOL)

    of gantry rotation speed, dose rate, and multi leaf collimator ... Background: The radiobiological models describe the effects of the radiation treatment on cancer and healthy ... delivery time and decrement in the number of monitor units.[3-5].

  9. Mathematical and physical models and radiobiology

    International Nuclear Information System (INIS)

    Lokajicek, M.

    1980-01-01

    The hit theory of the mechanism of biological radiation effects in the cell is discussed with respect to radiotherapy. The mechanisms of biological effects and of intracellular recovery, the cumulative radiation effect and the cumulative biological effect in fractionated irradiation are described. The benefit is shown of consistent application of mathematical and physical models in radiobiology and radiotherapy. (J.P.)

  10. National Radiobiology Archives Distributed Access user's manual

    International Nuclear Information System (INIS)

    Watson, C.; Smith, S.; Prather, J.

    1991-11-01

    This User's Manual describes installation and use of the National Radiobiology Archives (NRA) Distributed Access package. The package consists of a distributed subset of information representative of the NRA databases and database access software which provide an introduction to the scope and style of the NRA Information Systems

  11. Proceedings of the international conference on radiation biology and clinical applications: a molecular approach towards innovations in applied radiobiology and a workshop on strategies in radiation research

    International Nuclear Information System (INIS)

    2013-10-01

    Innovations in radiotherapy approaches to cancer and radiation biology research is of growing interest in radiation researchers to conduct preclinical studies at their centers and translating the results as soon as possible to clinical radiotherapy practice. Recent papers have greatly enriched the current knowledge of radiation oncology, especially radiobiology and molecular oncology, and this has radically changed the oncology practice in radiation therapy in just a few years. The conference theme highlights the molecular and cellular responses within tissue and higher levels of mammalian biological organization. New experimental radiobiology research to underpin current and future regulatory decisions setting workplace exposure limits. To develop rapid, high-precision analytical methods that assess radiation exposure doses from clinical samples and thus aid in the triage and medical management of radiological casualties. Innovative approaches to improve the accuracy, dose range, ease of use, and speed of classical biodosimetry. Papers relevant to INIS are indexed separately

  12. Research in radiobiology

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1959-10-15

    Safety in the production and use of radioactive substances and protection against ionizing radiation are matters of direct concern to the International Atomic Energy Agency. On the one hand, the Agency has been trying to establish standards of safe practice, and on the other, it has been trying to promote research on the biological effects of radiation. Radiobiological research is of basic importance in the context of the growing use of radiation sources all over the world, because measures of radiation protection or the treatment of radiation sickness can be adequate and effective only when there is a clear and thorough understanding of the effects of ionizing radiation on living organisms. IAEA has placed several contracts with scientific institutions in different countries for research on problems that may throw some light on various aspects of this problem. One line of research is to study the effects of small doses of radiation, a study that is essential in establishing the maximum permissible doses for radiation workers and others. A contract has been given to the Pharmacological Institute of Vienna University for the investigation of the response of cells, particularly of the nervous system, to low-level exposures. Another important field of research is the protective action of certain substances against the effects of radiation. Under a research contract given by IAEA, the mode of protective action of certain chemical compounds is being studied at the Physiological Institute of Vienna University. Of the possible effects of radiation, those of a genetic nature have caused widespread concern. Under an IAEA contract, cytogenetical investigations are being carried out at the Institute of Medical Genetics of Uppsala University on the effects of radiation on human cells grown in vitro. While certain conclusions about the effects of radiation on human cells can be deduced from test tube experiments, some valuable inferences can also be drawn from studies of the

  13. Melanomas: radiobiology and role of radiation therapy

    International Nuclear Information System (INIS)

    Peschel, Richard E.

    1995-01-01

    Purpose/Objective: This course will review the radiobiology of malignant melanoma (MM) and the clinical use of radiation therapy for metastatic melanoma and selected primary sites. The course will emphasize the scientific principles underlying the clinical treatment of MM. Introduction: The incidence of malignant melanoma has one of the fastest growth rates in the world. In 1991, there were 32,000 cases and 7,000 deaths from MM in the United States. By the year 2000, one of every 90 Americans will develop MM. Wide local excision is the treatment of choice for Stage I-II cutaneous MM. Five-year survival rates depend on (a) sex: female-63%, male-40%; (b) tumor thickness: t 4 mm-25%; (c) location: extremity-60%, trunk-41%; and (d) regional lymph node status: negative-77%, positive-31%. Despite adequate surgery, 45-50% of all MM patients will develop metastatic disease. Radiobiology: Both the multi-target model: S = 1-(1-e-D/Do)n and the linear quadratic mode: -In(S) = alpha x D + beta x D2 predict a possible benefit for high dose per fraction (> 400 cGy) radiation therapy for some MM cell lines. The extrapolation number (n) varies from 1-100 for MM compared to other mammalian cells with n=2-4. The alpha/beta ratios for a variety of MM cell lines vary from 1 to 33. Other radiobiologic factors (repair of potentially lethal damage, hypoxia, reoxygenation, and repopulation) predict a wide variety of clinical responses to different time-dose prescriptions including high dose per fraction (> 400 cGy), low dose per fraction (200-300 cGy), or b.i.d. therapy. Based on a review of the radiobiology of MM, no single therapeutic strategy emerges which could be expected to be successful for all tumors. Time-Dose Prescriptions: A review of the retrospective and prospective clinical trials evaluating various time-dose prescriptions for MM reveals: (1) MM is a radiosensitive tumor over a wide range of diverse time-dose prescriptions; and (2) The high clinical response rates to a

  14. Micro-and nanodosimetry for radiobiological planning in radiotherapy and cancer risk assessment in radiation environment

    International Nuclear Information System (INIS)

    Rosenfeld, A.B.

    2006-01-01

    Full text: Microdosimetry and nanodosimetry can provide unique information for prediction of radiobiological properties of radiation, which is important in radiation therapy for accurate dose planning and in radiation protection for cancer induction risk assessment. This demand measurements of the pattern of energies deposited by ionizing radiation on cellular scale and DNA levels.Silicon microelectronics technology is offering a unique opportunity for replacing gas proportional counters (TEPC) with miniature detectors for regional microdosimetry. Silicon on Insulator (SOI) technology has been used for the development of arrays of micron size sensitive volumes for modelling energy deposited in biological cells. The challenge in silicon microdosimetry is the development of well defined sensitive volume (SV) and full charge collection deposited by ionizing radiation in the SV. First generation SOI microdosimeters were developed at CMRP and investigated in a wide range of radiation fields for proton and neutron therapies and recently on isotopic neutron sources and heavy ions with energy up to lGeV/jj,m which are typical for deep space radiation environment. Microdosimetric spectra were obtained in a phantom that are well matched to TEPC and Monte Carlo simulations. Evidence that radiations with the same LET exhibit different biological effects demand development of new sensors sensitive to the track structure of ions or the type of particle for prediction of radiobiological effect of radiation using radiobiological models. New monolithic Si AE-E telescope of cellular size for simultaneous regional microdosimetry and particle identification will be presented and results will be discussed. The new design of the SOI microdosimeter is based on 3D micron and submicron size of Si SVs. This approach allows improvement in the accuracy of the Si microdosimetry because of full charge collection and the ability to measure low LET as low as 0.01 keV/jjm, which is similar to TEPC

  15. Influence of oxygen on the chemical stage of radiobiological mechanism

    International Nuclear Information System (INIS)

    Barilla, Jiří; Lokajíček, Miloš V.; Pisaková, Hana; Simr, Pavel

    2016-01-01

    The simulation of the chemical stage of radiobiological mechanism may be very helpful in studying the radiobiological effect of ionizing radiation when the water radical clusters formed by the densely ionizing ends of primary or secondary charged particle may form DSBs damaging DNA molecules in living cells. It is possible to study not only the efficiency of individual radicals but also the influence of other species or radiomodifiers (mainly oxygen) being present in water medium during irradiation. The mathematical model based on Continuous Petri nets (proposed by us recently) will be described. It makes it possible to analyze two main processes running at the same time: chemical radical reactions and the diffusion of radical clusters formed during energy transfer. One may study the time change of radical concentrations due to the chemical reactions running during diffusion process. Some orientation results concerning the efficiency of individual radicals in DSB formation (in the case of Co60 radiation) will be presented; the influence of oxygen present in water medium during irradiation will be shown, too. - Highlights: • Creation of the mathematical model. • Realization of the model with the help of Continuous Petri nets. • Obtain the time dependence of changes in the concentration of radicals. • Influence of oxygen on the chemical stage of radiobiological mechanism.

  16. Radiobiology studies for the evaluation of epithermal neutron beams used for BNCT

    International Nuclear Information System (INIS)

    Green, S.; Jones, B.; Mill, A.J.

    2006-01-01

    This paper outlines our plans for a study to establish the radiobiological effectiveness of the various mixes of radiation components present in an epithermal neutron beam designed for BNCT and to incorporate these data into clinical protocols for the treatment of malignant glioma. This is a description of work which is funded and just now beginning in Birmingham so no results can be presented. Our project will involve a combination of experimental measurements carried out in Birmingham and in Boston and mathematical modelling carried out in Birmingham. Despite all the extant in-vitro and in-vivo work, there is no widely accepted method to determine biological effect by accounting for variations in beam component mix, dose rate and treatment fractionation for disparate from the various BNCT centres. The objectives of this study are: To develop a cell-based radiobiology protocol to provide essential data on safety and efficacy of beams for Boron Neutron Capture Therapy (BNCT) in advance of clinical trials. To exploit the facilities at Massachusetts Institute of Technology for variable dose-rate epithermal irradiations to validate the above protocol. To develop mathematical models of this radiobiological system that can be used to inform decisions on dose selection, fractionation schedules, BNCT use as supplementary boosts or for re-treatment of recurrent cancers. To provide fundamental data relevant to the understanding of the radiobiology of simultaneous mixed high-and low-LET radiations over a clinically relevant dose-range. (author)

  17. Radiobiological studies with the nematode Caenorhabditis elegans. Genetic and developmental effects of high LET radiation

    International Nuclear Information System (INIS)

    Nelson, G.A.; Schubert, W.W.; Marshall, T.M.

    1992-01-01

    The biological effects of heavy charged particle (HZE) radiation are of particular interest to travellers and planners for long-duration space flights where exposure levels represents a potential health hazard. The unique feature of HZE radiation is the structured pattern of its energy deposition in targets. There are many consequences of this feature to biological endpoints when compared with effects of ionizing photons. Dose vs response and dose-rate kinetics may be modified, DNA and cellular repair systems may be altered in their abilities to cope with damage, and the qualitative features of damage may be unique for different ions. The nematode Caenorhabditis elegans is being used to address these and related questions associated with exposure to radiation. HZE-induced mutation, chromosome aberration, cell inactivation and altered organogenesis are discussed along with plans for radiobiological experiments in space. (author)

  18. National radiobiology archives Dr. J. Newell Stannard Collection Inventory Listing

    International Nuclear Information System (INIS)

    Watson, C.R.; Ligotke, E.K.; Smith, S.K.

    1994-11-01

    This document describes the National Radiobiology Archives (NRA) J. Newell Stannard Collection. Items in the Stannard Collection are available upon written request. The written correspondence should identify specific items, or the topic of the items, to be retrieved from the NRA holdings. The NRA is a Department of Energy Office of Health and Environmental Research (DOE/OHER) funded project at Pacific Northwest Laboratory (PNL). Dr. Charles R. Watson, telephone (509) 376-3483, is the project director. The NRA project is a comprehensive effort to gather, organize, and catalog data, tissues, and documents related to radiobiology studies. This archiving activity will provide future researchers with information for statistical analyses to compare results of these and other studies and materials for analysis and application of advanced molecular biology techniques

  19. Radiobiology of Proton Therapy - Results of an international expert workshop

    DEFF Research Database (Denmark)

    Lühr, Armin; von Neubeck, Cläre; Pawelke, Jörg

    2018-01-01

    The physical properties of proton beams offer the potential to reduce toxicity in tumor-adjacent normal tissues. Toward this end, the number of proton radiotherapy facilities has steeply increased over the last 10-15 years to currently around 70 operational centers worldwide. However, taking full...... in proton therapy combined with systemic treatments, and (4) testing biological effects of protons in clinical trials. Finally, important research avenues for improvement of proton radiotherapy based on radiobiological knowledge are identified. The clinical distribution of radiobiological effectiveness...... of protons alone or in combination with systemic chemo- or immunotherapies as well as patient stratification based on biomarker expressions are key to reach the full potential of proton beam therapy. Dedicated preclinical experiments, innovative clinical trial designs, and large high-quality data...

  20. Radiobiology of ultrasoft X-rays

    International Nuclear Information System (INIS)

    Raju, M.R.; Carpenter, S.; Chmielewski, J.; Schillaci, M.; Wilder, M.

    1985-01-01

    The goal of this program is to elucidate the principal physical, chemical, and biological mechanisms of radiation action in cells. The basic experiments for this program involve selected low- and high-energy x-ray sources and include studies of cell killing, both with and without modifiers (for example, hypoxia), determination of cellular age response, and measurement of induced DNA strand breaks, mutations, and chromosome aberrations. The theoretical effort involves Monte Carlo-based radiation track simulation codes to generate energy-deposition events and to follow the subsequent diffusion of chemical species. By combining the experimental and theoretical results, the authors plan to test assumptions used in existing models and to determine important parameters that should be included in any model. Ultrasoft x-rays (less than a few kiloelectron volts) provide a unique tool for studying induced biological lesions because x-rays produce photoelectrons with ranges much shorter than cellular dimensions but equivalent to the size of DNA strands and metaphase chromosomes

  1. Radiobiology of Cell Renewal Systems

    Energy Technology Data Exchange (ETDEWEB)

    Patt, H. M. [Laboratory of Radiobiology, University of California Medical Center, San Francisco, CA (United States)

    1968-08-15

    In recent years, considerable attention has been given to quantitative aspects of radiation effects on cell renewal systems. The behaviour of stem-type cells has been a focal point of interest, and it has been assumed by many that the fraction of surviving stem cells is the principal determinant of the probability of survival of the irradiated system or organism. The apparent close similarity in dose requirements for impairment of reproductive capacity, and the similarity in early repair and in stage sensitivity in vitro and in vivo.clearly indicate that purely cellular phenomena are reflected in the organized population. It does not necessarily follow, however, that there is a straightforward relationship between radiation effects on stem cells and the response of systems or organisms. Indeed, this is not so. It is abundantly clear that differential radiosensitivity is anchored in a number of variables that are associated with the organizational framework of the system and its environment. Many, but not all, effects can be understood in terms of the normal kinetics of the developmental pathway. Yet, deviations from normal kinetics that are minor in the steady state can have profound significance in the perturbed state. To understand the radiobiology of cell renewal systems and to place the many possible variables in reasonable perspective, we need to know a good deal more about the interplay of the component parts than we do at present. When we view the totality of an organized cell population, it seems necessary to postulate mechanisms external to any given cell in the regulation of the balanced sequence of proliferation and differentiation. At present, we have only a vague idea about this. Most attention has been directed to the proliferative process and it is encouraging to note the growing interest in the more developmental facets of cell renewal. (author)

  2. Neutron radiobiology. Summary of a workshop

    International Nuclear Information System (INIS)

    1978-01-01

    This report is a summary of a workshop held in June 1977 at Oak Ridge National Laboratory to evaluate the progress of research in the field of neutron radiobiology. The participants reviewed the results of current research and identified unresolved questions and areas of uncertainty. They then defined areas in which additional research should be undertaken, and, finally, they reviewed ways in which results from current and projected research could be applied to inform and influence regulatory decisions

  3. Cellular adverse actions of dibromoacetonitrile, a by-product in water bacterial control, at sublethal levels in rat thymocytes.

    Science.gov (United States)

    Kishida, Takumi; Akiyoshi, Kenji; Erdenedalai, Erdenebat; Enhetomuru, Anu; Imai, Shoji; Oyama, Yasuo

    2018-09-01

    The aim of this study was to investigate the effects of dibromoacetonitrile (DBAN), a by-product in water bacterial control, at sublethal concentrations on rat thymocytes, by using a cytometric technique with appropriate fluorescent dyes. By using this method, the possibility that DBAN induces cellular actions related to oxidative stress was assessed. DBAN reduced the content of cellular nonprotein thiols under Zn 2+ -free conditions. It elevated the intracellular level of Zn 2+ , being independent from external Zn 2+ . DBAN increased cell vulnerability to the cytotoxic action of hydrogen peroxide. These actions of DBAN were likely related to oxidative stress. DBAN is formed by the reaction of bromides and chlorinated oxidants during water disinfection. Hydrolysis of 2,2-dibromo-3-nitrilopropionamide, an antimicrobial used in hydraulic fracturing fluids for production of shale gas and oil, produces DBAN. Therefore, the concern regarding the levels of DBAN in industrial water systems is necessary to avoid the environmental risk to humans and wild mammals. Copyright © 2018 Elsevier Ltd. All rights reserved.

  4. The European Radiobiology Archives (ERA) - Content, structure and use illustrated by an example

    International Nuclear Information System (INIS)

    Gerber, G. B.; Wick, R. R.; Kellerer, A. M.; Hopewell, J. W.; Di Majo, V.; Dudoignon, N.; Goessner, W.; Stather, J.

    2006-01-01

    The European Radiobiology Archives (ERA), supported by the European Commission and the European Late Effect Project Group (EULEP), together with the US National Radiobiology Archives (NRA) and the Japanese Radiobiology Archives (JRA) have collected all information still available on long-term animal experiments, including some selected human studies. The archives consist of a database in Microsoft Access, a web site, databases of references and information on the use of the database. At present, the archives contain a description of the exposure conditions, animal strains, etc. from ∼350,000 individuals; data on survival and pathology are available from ∼200,000 individuals. Care has been taken to render pathological diagnoses compatible among different studies and to allow the lumping of pathological diagnoses into more general classes. 'Forms' in Access with an underlying computer code facilitate the use of the database. This paper describes the structure and content of the archives and illustrates an example for a possible analysis of such data. (authors)

  5. In vitro and in vivo ion beam targeted micro-irradiation for radiobiology

    International Nuclear Information System (INIS)

    Vianna, Francois

    2014-01-01

    The main goal of radiobiology is to understand the effects of ionizing radiations on the living. These past decades, ion microbeams have shown to be important tools to study for example the effects of low dose exposure, or the bystander effect. Since 2003, the CENBG has been equipped with a system to perform targeted micro-irradiation of living samples. Recently, microbeams applications on this subject have diversified and the study of DNA repair mechanisms at the cellular and multicellular scales, in vitro and in vivo, has become possible thanks to important evolutions of fluorescence imaging techniques and cellular biology. To take into account these new approaches, the CENBG micro-irradiation beamline has been entirely redesigned and rebuilt to implement new features and to improve the existing ones. My PhD objectives were i) commissioning the facility, ii) characterizing the system on track etch detectors, and on living samples, iii) implementing protocols to perform targeted irradiations of living samples with a con-trolled delivered dose, at the cellular and multicellular scales, and to visualize the early consequences online, iv) modelling these irradiations to explain the biological results using the calculated physical data. The work of these past years has allowed us i) to measure the performances of our system: a beam spot size of about 2 μm and a targeting accuracy of ± 2 μm, and to develop ion detection systems for an absolute delivered dose control, ii) to create highly localized radiation-induced DNA damages and to see online the recruitment of DNA repair proteins, iii) to apply these protocols to generate radiation-induced DNA damages in vivo inside a multicellular organism at the embryonic stage: Caenorhabditis elegans. These results have opened up many perspectives on the study of the interaction between ionizing radiations and the living, at the cellular and multicellular scales, in vitro and in vivo. (author) [fr

  6. Application of microdosimetry to radiobiology

    International Nuclear Information System (INIS)

    Zaider, M.; Rossi, H.H.

    1987-01-01

    The application of microdosimetry to radiobiology has frequently been based on the site model, i.e., the concept of a sensitive subcellular volume in which energy concentration determines the biological effect regardless of the nature of ionizing radiations. A later publication extended the treatment as to include the distance model in which lesion formation is assumed to depend on the initial separation of the two component sublesions. This was developed as a theoretical basis for the molecular ion experiment in which the biological effectiveness of pairs of ions is determined as a function of their separation. The results of this experiment made it evident that the effectiveness of single events must be largely determined by energy concentration in volumes having dimensions of less than a tenth of a micrometer. It can not be determined a priori whether this difference is due to a distance-dependent probability of combination between sublesions that are perhaps produced at random locations in a critical region of the cell (the gross sensitive volume, GSV), or whether the interaction probability is constant but the sensitive material is contained in a matrix that is within the GSV but has a complex geometrical shape. The generalized TDRA allows for either condition or their combination. In this paper it will be shown that regardless of the ultimate resolution of this question microdosimetry can retain its predictive role in radiobiology provided measurements are performed in a series of spherical sites (of different dimensions) rather than one single, micrometer-size volume

  7. Radiobiology of human cancer radiotherapy

    International Nuclear Information System (INIS)

    Andrews, J.R.

    1978-01-01

    The author has systematically collected and collated the scientific literature correlating the basic and clinical sciences in this field in order to produce a definitive treatise. The book thoroughly reviews the biology and biochemistry relevant to radiobiology and describes the critical locus for the extinction of cell reproductive capacity. Extensive coverage is given to oxygen effect, hyperthermia, high linear energy transfer, cell populations, and similar topics. Separate sections cover time, dose, and fractionation; radiation hematology; cancer chemotherapy; and cancer immunology. The book also contains invaluable discussions of techniques for optimizing radiotherapy alone and in combination with other therapies

  8. Characterization and performances of DOSION, a dosimetry equipment dedicated to radiobiology experiments taking place at GANIL

    Energy Technology Data Exchange (ETDEWEB)

    Boissonnat, Guillaume, E-mail: boissonnat@lpccaen.in2p3.fr [LPC (Normandie Univ-ENSICAEN-UNICAEN-CNRS/IN2P3), 6 Bd Maréchal Juin, 14050 Caen (France); Fontbonne, Jean-Marc [LPC (Normandie Univ-ENSICAEN-UNICAEN-CNRS/IN2P3), 6 Bd Maréchal Juin, 14050 Caen (France); Balanzat, Emmanuel [CIMAP (CEA/DSM-CNRS/INP-ENSICAEN-UNICAEN), Bd Henri Becquerel, 14076 Caen (France); Boumard, Frederic; Carniol, Benjamin [LPC (Normandie Univ-ENSICAEN-UNICAEN-CNRS/IN2P3), 6 Bd Maréchal Juin, 14050 Caen (France); Cassimi, Amine [CIMAP (CEA/DSM-CNRS/INP-ENSICAEN-UNICAEN), Bd Henri Becquerel, 14076 Caen (France); Colin, Jean; Cussol, Daniel; Etasse, David; Fontbonne, Cathy [LPC (Normandie Univ-ENSICAEN-UNICAEN-CNRS/IN2P3), 6 Bd Maréchal Juin, 14050 Caen (France); Frelin, Anne-Marie [GANIL (CEA/DSM-CNRS/IN2P3), Bd Henri Becquerel, 14076 Caen (France); Hommet, Jean; Salvador, Samuel [LPC (Normandie Univ-ENSICAEN-UNICAEN-CNRS/IN2P3), 6 Bd Maréchal Juin, 14050 Caen (France)

    2017-06-01

    Currently, radiobiology experiments using heavy ions at GANIL (Grand Accélérateur National d′Ions Lourds) are conducted under the supervision of the CIMAP (Center for research on Ions, MAterials and Photonics). In this context, a new beam monitoring equipment named DOSION has been developed. It allows to perform measurements of accurate fluence and dose maps in near real time for each biological sample irradiated. In this paper, we present the detection system, its design, performances, calibration protocol and measurements performed during radiobiology experiments. This setup is currently available for any radiobiology experiments if one wishes to correlate one's own sample analysis to state-of-the-art dosimetric references.

  9. Radiobiological researches on Dianthus caryophyllus L. carnation chimeras

    International Nuclear Information System (INIS)

    Pereau-Leroy, Pierre

    1975-01-01

    This research thesis reports a radiobiological study of Dianthus periclinal chimeras performed by submitting plants and plant cuttings at different physiological stages to cobalt-60 gamma irradiation under different dose conditions and rates. The effects of these treatments are studied while growing the so-processed plants and by microscopic examination of sections of irradiated meristems [fr

  10. Tritium radiobiology research in the US DOE program

    International Nuclear Information System (INIS)

    Carsten, A.L.

    1986-01-01

    The history of the original US Atomic Energy Commission, its replacement, the Energy Research and Development Administration, and the present Department of Energy's interest and sponsorship of tritium radiobiology is reviewed beginning in 1971 and continuing through 1986. In particular, the four remaining US Department of Energy, Division of Health and Environmental Research programs are described in some detail

  11. Research in radiobiology. Annual report, Internal Irradiation Program

    International Nuclear Information System (INIS)

    Miller, S.C.; Buster, D.S.

    1985-01-01

    The annual progress report for the Radiobiology Division of the University of Utah College of Medicine is presented. Summaries of twenty-four projects concerning the metabolism, dosimetry and toxicity of a variety of actinide elements in beagles or rats are given. Individual papers within this report have been separately indexed and abstracted for the data base

  12. What kind of radiobiology should be done at a hadron therapy center

    International Nuclear Information System (INIS)

    Kraft, G.; Kraft-Weyrather, W.; Taucher-Scholz, G.; Scholz, M.

    1997-01-01

    Although therapy with heavy particles like neutrons, protons or heavier ions has now a rather long history of several decades, but there are more open questions than settled problems. This fact is really amazing because the use of the high LET particles, neutrons and heavy ions was strongly motivated by radiobiological arguments. Presently, the use of protons with a better physical dose distribution is more widely accepted than neutrons or heavy ions where the expected high LET benefit could not be verified clinically. This demonstrates that predictions made on the basis of radiobiological experiments cannot be transferred directly from in vitro experiments to the therapy situation. In particular, it is not possible to transfer an average RBE value measured in vitro in an extended exposure field to the treatment situation. Therefore, in the following section the dependence of RBE on LET, dose and radiosensitivity will be summarized and compared to models. Basic experiments illustrating the RBE problem in a particle field will be described. The fundamentals of a recently developed track structure model will be given and calculations will be compared to experiments. Finally, a short outline of possible future developments for radiobiology will be presented. (orig.)

  13. Radiobiology and dosimetry

    International Nuclear Information System (INIS)

    Saenger, E.L.; Kereiakes, J.G.

    1975-01-01

    A brief review of radiobiology is presented that should indicate the reasonable limits of pediatric nuclear medicine. Together with the dosimetric information and the few caveats of laboratory procedure, the use of nuclear medicine as clinically indicated, maintaining doses as low as practicable, should be readily applied to pediatrics. In discussing benefits versus risks in nuclear medicine, the conscience guide (CG) was introduced as a unit, being defined as the referral rate to better qualified centers from a laboratory where expertise in a given test is lacking versus the total number of examinations done in that laboratory. When considering procedures in the pediatric age group, the physician is urged to use the CG to do only those procedures for which he and his staff have adequate equipment and experience. In this way, the best interests of the patient and physician can be insured. (auth)

  14. Radiobiological compensation: A case study of uterine cervix cancer with concurrent chemotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Herrera, Higmar; Yanez, Elvia; Lopez, Jesus [Centro Estatal de Cancerologia de Durango, Victoria de Durango, Durango (Mexico); ISSSTE General Hospital Dr. Santiago Ramon y Cajal, Victoria de Durango, Durango (Mexico)

    2012-10-23

    The case of a patient diagnosed with uterine cervix cancer is presented as an example of the clinical application of the radiobiological compensation method implemented at Centro Estatal de Cancerologia de Durango. Radiotherapy treatment was initially modified to compensate for the chemotherapy component and, as medical complications arose during treatment delivery resulting in an 18 days gap, new compensation followed. All physical and radiobiological assumptions to calculate the Biologically Effective Dose in the external beam and brachytherapy parts of the treatment are presented. Good local control of the tumor was achieved, the theoretical tolerance limits for the organs at risk were not surpassed and the patient manifested no extensive morbidity.

  15. National Radiobiology Archives Distributed Access user's manual

    Energy Technology Data Exchange (ETDEWEB)

    Watson, C.; Smith, S. (Pacific Northwest Lab., Richland, WA (United States)); Prather, J. (Linfield Coll., McMinnville, OR (United States))

    1991-11-01

    This User's Manual describes installation and use of the National Radiobiology Archives (NRA) Distributed Access package. The package consists of a distributed subset of information representative of the NRA databases and database access software which provide an introduction to the scope and style of the NRA Information Systems.

  16. Cancer radiobiology

    International Nuclear Information System (INIS)

    Almahi, W.A.A.

    2006-03-01

    The work i have done in this dissertation, was mainly aimed at the literature review of radiotherapy radiobiology discussing the cure of tumours with ionizing radiation, from both the biological and physical point of view. The first chapter an introduction about the radiotherapy and includes: definition, working dose, benefit of radiotherapy, risk of radiotherapy, external and internal radiotherapy and treatment planing. In chapter two the theories of radiobiology and main effects caused by the radiation in the interaction with the biological matter were explained, the damages caused by the use of low and high LET (linear energy transfer) particles to mammalian cells were discussed. And discuss a therapeutic advantage may be gained by one of four hypothetical mechanism: repair the damage of DAN, so when sublethal injury can be repaired if no further hits are sustained. Also the reoxygenation of tumor is important for its effects on stabilization of free radicals produced by ionizing radiation. Hypoxic cells generally require an increased dose of radiation for lethal effect, redistribution, within the cell cycle depends on location of cells and their radiosensitivity also cells undergoing DNA synthesis, the S phase, are much more radioresistant than cells in other phase of the cell cycle, and repopulation of tumor cells is indicator of the surviving cells respond by increased regeneration or repopulation. Repopulation is a greater problem with rapidly proliferating tumors than slower growing neoplasms. These mechanisms are known as the classical four R's of radiation biology. One of the important applications of radiobiology is the radiotherapy and cancer treatment, experimental and theoretical studies in radiation biology contribute to the development of radiotherapy, in this dissertation we discussed the dose response relation so as the size of the tumor increases, and the dose needed for local control like wise increases, the risk of injury to normal tissue

  17. Radiation monitoring considerations for radiobiology facilities

    International Nuclear Information System (INIS)

    McClelland, T.W.; McFall, E.D.

    1976-01-01

    Battelle, Pacific Northwest Laboratories, conducts a wide variety of radiobiology and radioecology research in a number of facilities on the Hanford Reservation. Review of radiation monitoring problems associated with storage, plant and animal experiments, waste handling and sterile facilities shows that careful monitoring, strict procedural controls and innovative techniques are required to minimize occupational exposure and control contamination. Although a wide variety of radioactivity levels are involved, much of the work is with extremely low level materials. Monitoring low level work is mundane and often impractical but cannot be ignored in today's ever tightening controls

  18. Physics and radiobiology of nuclear medicine

    CERN Document Server

    Saha, Gopal B

    2010-01-01

    From a distinguished author comes this new edition for technologists, practitioners, residents, and students in radiology and nuclear medicine. Encompassing major topics in nuclear medicine from the basic physics of radioactive decay to instrumentation and radiobiology, it is an ideal review for Board and Registry examinations. The material is well organized and written with clarity. The book is supplemented with tables and illustrations throughout. It provides a quick reference book that is concise but comprehensive, and offers a complete discussion of topics for the nuclear medicine and radi

  19. SU-F-T-03: Radiobiological Evaluation of a Directional Brachytherapy Device Surgically Implanted Following EBRT

    Energy Technology Data Exchange (ETDEWEB)

    Rivard, MJ [Tufts University School of Medicine, Boston, MA (United States); Emrich, JG; Poli, J [Drexel University College of Medicine, Philadelphia, PA (United States)

    2016-06-15

    Purpose: Preceding surgical implantation following external-beam radiotherapy (EBRT) delivery, a radiobiological evaluation was performed for a new LDR Pd-103 directional brachytherapy device (CivaSheet). As this was the first case with the device used in combination with EBRT, there was concern to determine the appropriate prescription dose. Methods: The radiobiological model of Dale (1985, 1989) was used for a permanent LDR implant including radioactive decay. The biological effective dose (BED) was converted to the equivalent dose in 2 Gy fractions (EQD2) for comparison with EBRT prescription expectations. Given IMRT delivery of 50.4 Gy, an LDR brachytherapy dose of approximately 15–20 Gy EQD2 was desired. To be specific to the treatment site (leiomyosarcoma T2bN0M0, grade 2 with R1 surgical margin), the radiobiological model required several radiobiological parameters with values taken from the literature. A sensitivity analysis was performed to determine their relative importance on the calculated BED and subsequent EQD2. The Pd-103 decay constant (λ=0.0017 h{sup −1}) was also used. DVHs were prepared for pre- and post-surgical geometries to glean the possible and realized implant geometric configuration. DVHs prepared in VariSeed9 were converted to BEDVHs and subsequently EQD2 values for each volume-element. Results: For a physical dose of 28 Gy to a 0.5 cm depth, BED=21.7 Gy and EQD2=17.6 Gy, which was near the center of the desired EQD2 range. Tumor bed (CTV=4 cm{sup 3}) coverage was 99.2% with 48 sources implanted. In order of decreasing importance from the sensitivity analysis, the radiobiological parameters were α=0.25 Gy{sup −1}, T{sub POT}=23 days, α/β=8.6 Gy, and T=1.5 h. Percentage variations in these values produced EQD2 variations of 40%, 20%, 18%, and 1%, respectively. Conclusion: This radiobiological evaluation indicated that prescription dose may be determined for comparison with the desired EQD2, and that radiobiologicalparameter

  20. Radiobiological compensation: A case study of uterine cervix cancer with concurrent chemotherapy

    International Nuclear Information System (INIS)

    Herrera, Higmar; Yañez, Elvia; López, Jesús

    2012-01-01

    The case of a patient diagnosed with uterine cervix cancer is presented as an example of the clinical application of the radiobiological compensation method implemented at Centro Estatal de Cancerología de Durango. Radiotherapy treatment was initially modified to compensate for the chemotherapy component and, as medical complications arose during treatment delivery resulting in an 18 days gap, new compensation followed. All physical and radiobiological assumptions to calculate the Biologically Effective Dose in the external beam and brachytherapy parts of the treatment are presented. Good local control of the tumor was achieved, the theoretical tolerance limits for the organs at risk were not surpassed and the patient manifested no extensive morbidity.

  1. Radiobiological compensation: A case study of uterine cervix cancer with concurrent chemotherapy

    Science.gov (United States)

    Herrera, Higmar; Yañez, Elvia; López, Jesús

    2012-10-01

    The case of a patient diagnosed with uterine cervix cancer is presented as an example of the clinical application of the radiobiological compensation method implemented at Centro Estatal de Cancerología de Durango. Radiotherapy treatment was initially modified to compensate for the chemotherapy component and, as medical complications arose during treatment delivery resulting in an 18 days gap, new compensation followed. All physical and radiobiological assumptions to calculate the Biologically Effective Dose in the external beam and brachytherapy parts of the treatment are presented. Good local control of the tumor was achieved, the theoretical tolerance limits for the organs at risk were not surpassed and the patient manifested no extensive morbidity.

  2. Wavefront cellular learning automata.

    Science.gov (United States)

    Moradabadi, Behnaz; Meybodi, Mohammad Reza

    2018-02-01

    This paper proposes a new cellular learning automaton, called a wavefront cellular learning automaton (WCLA). The proposed WCLA has a set of learning automata mapped to a connected structure and uses this structure to propagate the state changes of the learning automata over the structure using waves. In the WCLA, after one learning automaton chooses its action, if this chosen action is different from the previous action, it can send a wave to its neighbors and activate them. Each neighbor receiving the wave is activated and must choose a new action. This structure for the WCLA is necessary in many dynamic areas such as social networks, computer networks, grid computing, and web mining. In this paper, we introduce the WCLA framework as an optimization tool with diffusion capability, study its behavior over time using ordinary differential equation solutions, and present its accuracy using expediency analysis. To show the superiority of the proposed WCLA, we compare the proposed method with some other types of cellular learning automata using two benchmark problems.

  3. Wavefront cellular learning automata

    Science.gov (United States)

    Moradabadi, Behnaz; Meybodi, Mohammad Reza

    2018-02-01

    This paper proposes a new cellular learning automaton, called a wavefront cellular learning automaton (WCLA). The proposed WCLA has a set of learning automata mapped to a connected structure and uses this structure to propagate the state changes of the learning automata over the structure using waves. In the WCLA, after one learning automaton chooses its action, if this chosen action is different from the previous action, it can send a wave to its neighbors and activate them. Each neighbor receiving the wave is activated and must choose a new action. This structure for the WCLA is necessary in many dynamic areas such as social networks, computer networks, grid computing, and web mining. In this paper, we introduce the WCLA framework as an optimization tool with diffusion capability, study its behavior over time using ordinary differential equation solutions, and present its accuracy using expediency analysis. To show the superiority of the proposed WCLA, we compare the proposed method with some other types of cellular learning automata using two benchmark problems.

  4. The status and role of radiobiology in veterinary medicine

    International Nuclear Information System (INIS)

    Benova, K.

    2007-01-01

    In this presentation author deals with history of the University of Veterinary Medicine in Kosice as well as with the status and role of radiobiology in veterinary medicine. Some results of gamma irradiation of Pecilia reticulata are presented. Activity levels of cesium-137 in contaminated mushrooms gathered in Slovakia in 2001 are presented.

  5. Scientific projection paper for space radiobiological research

    International Nuclear Information System (INIS)

    Vinograd, S.P.

    1980-01-01

    A nationale for the radiobiological research requirements for space is rooted in a national commitment to the exploration of space, mandated in the form of the National Space Act. This research is almost entirely centered on man; more specifically, on the effects of the space radiation environment on man and his protection from them. The research needs discussed in this presentation include the space radiation environment; dosimetry; radiation biology-high LET particles (dose/response); and operational countermeasures

  6. Problems of radiation medicine and radiobiology

    International Nuclear Information System (INIS)

    Bazyka, D.A.

    2014-01-01

    Research activities and scientific advance achieved in 2013 at the State Institution 'National Research Center for Radiation Medicine of the National Academy of Medical Sciences of Ukraine' (NRCRM) concerning medical problems of the Chornobyl disaster, radiation medicine, radiobiology, radiation hygiene and epidemiology in collaboration with the WHO network of medical preparedness and assistance in radiation accidents are outlined in the annual report. Key points include the research results of XRCC1 and XPD gene polymorphism in thyroid cancer patients, CD38 gene GG genotype as a risk factor for chronic lymphocytic leukemia, frequency of 185delAG and 5382insC mutations in BRCA1 gene in women with breast cancer, cognitive function and TERF1, TERF2, TERT gene expression both with telomere length in human under the low dose radiation exposure. The 'source-scattering/shielding structures-man' models for calculation of partial dose values to the eye lens and new methods for radiation risk assessment were developed and adapted. Radiation risks of leukemia including chronic lymphocytic leukemia in the cohort of liquidators were published according to the 'case-control' study results after 20 years of survey. Increase of non-tumor morbidity in liquidators during the 1988-2011 with the maximum level 12-21 years upon irradiation was found. Incidence in evacuees appeared being of two-peak pattern i.e. in the first years after the accident and 12 years later. Experimental studies have concerned the impact of radio-modifiers on cellular systems, reproductive function in the population, features of the child nutrition in radiation contamination area were studied. Report also shows the results of scientific and organizational, medical and preventive work, staff training, and implementation of innovations. The NRCRM Annual Report was approved at the Scientific Council meeting of NAMS on March 3, 201

  7. Radiation induced DNA damage and repair in mutagenesis

    International Nuclear Information System (INIS)

    Strniste, G.F.; Chen, D.J.; Okinaka, R.T.

    1987-01-01

    The central theme in cellular radiobiological research has been the mechanisms of radiation action and the physiological response of cells to this action. Considerable effort has been directed toward the characterization of radiation-induced DNA damage and the correlation of this damage to cellular genetic change that is expressed as mutation or initiating events leading to cellular transformation and ultimately carcinogenesis. In addition, there has been a significant advancement in their understanding of the role of DNA repair in the process of mutation leading to genetic change in cells. There is extensive literature concerning studies that address radiation action in both procaryotic and eucaryotic systems. This brief report will make no attempt to summarize this voluminous data but will focus on recent results from their laboratory of experiments in which they have examined, at both the cellular and molecular levels, the process of ionizing radiation-induced mutagenesis in cultured human cells

  8. Radiation biology. Chapter 20

    Energy Technology Data Exchange (ETDEWEB)

    Wondergem, J. [International Atomic Energy Agency, Vienna (Austria)

    2014-09-15

    Radiation biology (radiobiology) is the study of the action of ionizing radiations on living matter. This chapter gives an overview of the biological effects of ionizing radiation and discusses the physical, chemical and biological variables that affect dose response at the cellular, tissue and whole body levels at doses and dose rates relevant to diagnostic radiology.

  9. BNL ACCELERATOR-BASED RADIOBIOLOGY FACILITIES

    International Nuclear Information System (INIS)

    LOWENSTEIN, D.I.

    2000-01-01

    For the past several years, the Alternating Gradient Synchrotron (AGS) at Brookhaven National Laboratory (USA) has provided ions of iron, silicon and gold, at energies from 600 MeV/nucleon to 10 GeV/nucleon, for the US National Aeronautics and Space Administration (NASA) radiobiology research program. NASA has recently funded the construction of a new dedicated ion facility, the Booster Applications Facility (BAF). The Booster synchrotron will supply ion beams ranging from protons to gold, in an energy range from 40--3,000 MeV/nucleon with maximum beam intensities of 10 10 to 10 11 ions per pulse. The BAF Project is described and the future AGS and BAF operation plans are presented

  10. Radiobiology Department. Report of Activities 1977-1980

    International Nuclear Information System (INIS)

    1982-02-01

    The different research activities carried out by the Radiobiology Department of the CNEA over the 4-year period 1977-1980 are summarized. These activities were devoted to the study of the effects of radiation on different biological systems, to the search for adequate experimental models, and to the development of techniques permiting a correct evaluation of the information obtained. Topics covered are genetics, microbiology, somatic effects of radiation, pathology and the operation of the animal's house. (M.E.L.) [es

  11. Biometrical analysis in radiobiological works of N.V. Luchnik

    International Nuclear Information System (INIS)

    Glotov, N.V.

    1996-01-01

    The contribution of the famous Russian geneticist and biophysics N.V. Luchnik into biometrical analysis of radiobiological data is discussed. His works on radiation mortality of mice (2) and the process of post-radiation repair of chromosome aberrations (10) are thoroughly observed. The conclusion of necessity to develop biometrical analysis as separate part of biometry is made

  12. Experimental radiotherapy and clinical radiobiology. Vol. 8, special issue 1. Proceedings

    International Nuclear Information System (INIS)

    Doerr, W.; Baumann, M.; Herrmann, T.

    1999-01-01

    The publication contains the abstracts of all papers and posters presented at the symposium. The headings were as follows: Radiobiology of the lung, mediation of radiation damage in the lung, clinical studies, future clinical directions, as well as documentation and management. (MG)

  13. Development of fast neutron therapy worldwide. Radiobiological, clinical and technical aspects

    International Nuclear Information System (INIS)

    Wambersie, A.; Richard, F.; Breteau, N.

    1994-01-01

    Radiobiological data indicate that fast neutrons could bring a benefit in the treatment of some tumour types, and suggest mechanisms through which this benefit could be achieved. However, radiobiology also clearly indicates that there is a need for patient selection as well as for a high-physical selectivity. The main difficulty when interpreting the results of neutron therapy are the poor technical conditions in which the first treatments were applied. This explains why the value and the place of neutron therapy are not universally recognized, although more than 15000 patients have been treated so far worldwide. There are, however, clinical indications of fast neutrons bringing a benefit for the following tumour sites: salivary glands, paranasal sinuses, soft tissue sarcomas, prostatic adenocarcinomas, palliative treatment of melanoma and rectum. These tumours represent about 10-15% of all patients currently referred to the radiation therapy departments. (orig.)

  14. Some applications of radiation chemistry to biochemistry and radiobiology

    International Nuclear Information System (INIS)

    Wardman, P.

    1987-01-01

    In this chapter illustrate the use of radiation chemistry as a tool in investigating biologically important radical reactions, and also outline some studies of models for radiobiological damage. Because aqueous solutions usually offer the most important matrix, an appreciation of the main features of water radiolysis will be essential. Most of the illustrations involve pulse radiolysis, and some familiarity with chemical kinetics is assumed. In addition to these and other chapters in this book, readers find the proceedings of a recent NATO Advanced Study Institute most useful. The authors shall not try to review here all the applications of radiation chemistry to biochemistry and biology, but they will illustrate, using selected examples, the main principles and practical advantages and problems. Another recent volume covers the main contributions of flash photolysis and pulse radiolysis to the chemistry of biology and medicine, complementing earlier reviews. Papers from symposia on radical processes in radiobiology and carcinogenesis, and on super-oxide dismutases, and proceedings of recent international congresses of radiation research, together with the other publications referred to above will enable the reader to gain a comprehensive overview of the role of radicals in biological processes and the contributions of radiation chemistry

  15. The challenge for the paradigms heat have guided the radiobiology in the past

    International Nuclear Information System (INIS)

    Real, A.

    2001-01-01

    Until recently, it has been commonly accepted that the biological consequences following ionizing radiation exposure are attributable to direct DNA damage. However, in the last decade some evidence have emerged to suggest that the classical genetic effects associated with radiation exposure (i.e. mutations, chromosomal aberrations, micronucleus) are not necessarily the result of the direct damage induced in the cellular DNA. These effects have been termed non-targeted and include radiation-induced genomic instability, effects detected after cytoplasmic irradiation and bystander effects. All of them support the hypothesis that important genetic consequences of radiation may arise in cells that in themselves receive no direct radiation exposure at all. The radioinduced damage signals could be transmitted to these cells from those that have been directly irradiated. The non-targeted effects challenge the paradigms that have guided radiobiology in the past and may change our thinking about the early events in the carcinogenic process and in particular about the critical targets for genetic and carcinogenic damage by radiation. These effects could be particularly important at low doses, when non all the cells are directly exposed to an ionizing track. (Author) 45 refs

  16. Dosimetry and radiobiology of negative pions and heavy ions

    International Nuclear Information System (INIS)

    Raju, M.R.

    1978-01-01

    The depth dose distribution of pion beams has not been found superior to protons. Pion radiation quality at the plateau region is comparable to conventional low-LET radiations, and radiobiology results also indicate RBE values close to unity. In the pion stopping region, the radiation quality increases considerably. Radiobiology data for negative pions at the Bragg peak position clearly indicate the increase in RBE and the reduction in OER. Even at the Bragg peak position, compared to fast neutrons, the average LET of negative pions is lower. Pion radiobiology data have indicated lower RBE values and higher OER values compared to fast neutrons. The radiation quality of fast neutrons is in between that of carbon and neon ions at the peak region and that of neon ions at the plateau is lower than for fast neutrons. The mean LET value for helium ions, even at the distal end of the peak, is lower than for fast neutrons. Dose localization of heavy ions has been found to decrease slowly with increasing charge of the heavy ion. The intercellular contact that protects cells after exposure to low-LET radiations is not detected after exposure to heavy ions. Single and fractionated doses of heavy ions produce dose-response curves for heavy ions having reduced shoulders but similar slopes when compared to gamma rays. Fractionated treatments of heavy ions produce an enhanced effect in the peak region compared to the plateau region and could lead to a substantial gain in therapeutic ratio. The OER for protons was similar to that for x rays. The OER values for negative pions, helium ions, and carbon ions were larger, for neon ions similar, and for argon ions smaller when compared to fast neutrons.Negative pions, helium ions, and carbon ions may be very effective clinically because the radiation quality of these beams is similar to that of the mixed scheme of neutrons and x rays

  17. Monte Carlo studies on photon interactions in radiobiological experiments

    Science.gov (United States)

    Shahmohammadi Beni, Mehrdad; Krstic, D.; Nikezic, D.

    2018-01-01

    X-ray and γ-ray photons have been widely used for studying radiobiological effects of ionizing radiations. Photons are indirectly ionizing radiations so they need to set in motion electrons (which are a directly ionizing radiation) to perform the ionizations. When the photon dose decreases to below a certain limit, the number of electrons set in motion will become so small that not all cells in an “exposed” cell population can get at least one electron hit. When some cells in a cell population are not hit by a directly ionizing radiation (in other words not irradiated), there will be rescue effect between the irradiated cells and non-irradiated cells, and the resultant radiobiological effect observed for the “exposed” cell population will be different. In the present paper, the mechanisms underlying photon interactions in radiobiological experiments were studied using our developed NRUphoton computer code, which was benchmarked against the MCNP5 code by comparing the photon dose delivered to the cell layer underneath the water medium. The following conclusions were reached: (1) The interaction fractions decreased in the following order: 16O > 12C > 14N > 1H. Bulges in the interaction fractions (versus water medium thickness) were observed, which reflected changes in the energies of the propagating photons due to traversals of different amount of water medium as well as changes in the energy-dependent photon interaction cross-sections. (2) Photoelectric interaction and incoherent scattering dominated for lower-energy (10 keV) and high-energy (100 keV and 1 MeV) incident photons. (3) The fractions of electron ejection from different nuclei were mainly governed by the photoelectric effect cross-sections, and the fractions from the 1s subshell were the largest. (4) The penetration fractions in general decreased with increasing medium thickness, and increased with increasing incident photon energy, the latter being explained by the corresponding reduction in

  18. Monte Carlo studies on photon interactions in radiobiological experiments.

    Directory of Open Access Journals (Sweden)

    Mehrdad Shahmohammadi Beni

    Full Text Available X-ray and γ-ray photons have been widely used for studying radiobiological effects of ionizing radiations. Photons are indirectly ionizing radiations so they need to set in motion electrons (which are a directly ionizing radiation to perform the ionizations. When the photon dose decreases to below a certain limit, the number of electrons set in motion will become so small that not all cells in an "exposed" cell population can get at least one electron hit. When some cells in a cell population are not hit by a directly ionizing radiation (in other words not irradiated, there will be rescue effect between the irradiated cells and non-irradiated cells, and the resultant radiobiological effect observed for the "exposed" cell population will be different. In the present paper, the mechanisms underlying photon interactions in radiobiological experiments were studied using our developed NRUphoton computer code, which was benchmarked against the MCNP5 code by comparing the photon dose delivered to the cell layer underneath the water medium. The following conclusions were reached: (1 The interaction fractions decreased in the following order: 16O > 12C > 14N > 1H. Bulges in the interaction fractions (versus water medium thickness were observed, which reflected changes in the energies of the propagating photons due to traversals of different amount of water medium as well as changes in the energy-dependent photon interaction cross-sections. (2 Photoelectric interaction and incoherent scattering dominated for lower-energy (10 keV and high-energy (100 keV and 1 MeV incident photons. (3 The fractions of electron ejection from different nuclei were mainly governed by the photoelectric effect cross-sections, and the fractions from the 1s subshell were the largest. (4 The penetration fractions in general decreased with increasing medium thickness, and increased with increasing incident photon energy, the latter being explained by the corresponding reduction in

  19. Feasibility studies of colorless LR 115 SSNTD for alpha-particle radiobiological experiments

    International Nuclear Information System (INIS)

    Chan, K.F.; Tse, A.K.W.; Fong, W.F.; Yu, K.N.

    2006-01-01

    The feasibility of using the active layer of the colorless LR 115 SSNTD for alpha-particle radiobiological experiments was studied. The track revelation time on the bottom side (the side attached to the polyester base) was much longer than that on the top side (the side not attached to the polyester base) of the active layer so track formation on the top side was more desirable. In relation to this, culture of HeLa cells on the bottom side of the active layer was found feasible although the cultured cell number was relatively smaller. The feasibility of using this SSNTD for alpha-particle radiobiological experiments was demonstrated by culturing cells on the bottom side while performing alpha-particle irradiation and chemical etching on the top side, and by taking photographs of the cells and alpha-particle tracks together under the optical microscope

  20. Radiobiological effects in small mammals populations dwelled at radioactive waste disposal sites

    International Nuclear Information System (INIS)

    Sypin, V.D.; Osipov, A.N.; Pol'skij, O.G.; Elakov, A.L.; Egorov, V.G.; Synsynys, B.I.

    2004-01-01

    A major issue in evaluating the ecological acceptability of a disposal system for radioactive waste is in preventing the ecological risk that may arise from exposures in the distant future. There is uncertainty surrounding any estimate of these doses or risks due to lack of knowledge about future conditions. Therefore, the adequate estimation of the ecological acceptability of a radioactive waste disposal system required a complex radioecological and radiobiological approach. Environmental surveillance at the Sergievo-Posadsky radioactive waste disposal system of the Scientific and Industrial Association Radon in additional to a standard complex radiological testing includes also the study of the radiobiological effects in different biological objects sampled from the contaminated areas. In present report the results obtained on small rodents (mice and voles) sampled from the strict mode and fence zones of this disposal system are displayed and discussed. (author)

  1. Computer simulation in cell radiobiology

    International Nuclear Information System (INIS)

    Yakovlev, A.Y.; Zorin, A.V.

    1988-01-01

    This research monograph demonstrates the possible ways of using stochastic simulation for exploring cell kinetics, emphasizing the effects of cell radiobiology. In vitro kinetics of normal and irradiated cells is the main subject, but some approaches to the simulation of controlled cell systems are considered as well: the epithelium of the small intestine in mice taken as a case in point. Of particular interest is the evaluation of simulation modelling as a tool for gaining insight into biological processes and hence the new inferences from concrete experimental data, concerning regularities in cell population response to irradiation. The book is intended to stimulate interest among computer science specialists in developing new, more efficient means for the simulation of cell systems and to help radiobiologists in interpreting the experimental data

  2. Experimental radiotherapy and clinical radiobiology. Vol. 18. Proceedings

    International Nuclear Information System (INIS)

    Baumann, Michael; Dahm-Daphi, Jochen; Dikomey, Ekkehard; Petersen, Cordula; Rodemann, H. Peter; Zips, Daniel

    2009-01-01

    The proceedings on experimental radiotherapy and clinical radiobiology contain two review articles (prediction of normal tissue reactions after radiotherapy, ?H2AX foci as a marker for DNA double-strand breaks) and 34 contributions to the following topics: Hypoxia and molecular mechanisms of radiation resistance; biological imaging of the tumor micromilieu; DNA repair, genomic instability and carcerogenesis; molecular factors of radiation resistance; actual controversial discussion on possible irradiation caused metastasis risk enhancement; EGFR inhibition and irradiation; biology of experimental radiation/ normal tissue toxicity

  3. Apoptosis, energy metabolism, and fraction of radiobiologically hypoxic cells: a study of human melanoma multicellular spheroids.

    Science.gov (United States)

    Rofstad, E K; Eide, K; Skøyum, R; Hystad, M E; Lyng, H

    1996-09-01

    The magnitude of the fraction of radiobiologically hypoxic cells in tumours is generally believed to reflect the efficiency of the vascular network. Theoretical studies have suggested that the hypoxic fraction might also be influenced by biological properties of the tumour cells. Quantitative experimental results of cell energy metabolism, hypoxia- induced apoptosis, and radiobiological hypoxia are reported here. Human melanoma multicellular spheroids (BEX-c and WIX-c) were used as tumour models to avoid confounding effects of the vascular network. Radiobiological studies showed that the fractions of hypoxic cells in 1000-microM spheroids were 32 +/- 12% (BEX-c) and 2.5 +/- 1.1% (WIX-c). The spheroid hypoxic volume fractions (28 +/- 6% (BEX-c) and 1.4 +/- 7% (WIX-c)), calculated from the rate of oxygen consumption per cell, the cell packing density, and the thickness of the viable rim, were similar to the fractions of radiobiologically hypoxic cells. Large differences between tumours in fraction of hypoxic cells are therefore not necessarily a result of differences in the efficiency of the vascular network. Studies of monolayer cell cultures, performed to identify the biological properties of the BEX-c and WIX-c cells leading to this large difference in fraction of hypoxic cells, gave the following results: (1) WIX-c showed lower cell surviving fractions after exposure to hypoxia than BEX-c, (2) WIX-c showed higher glucose uptake and lactate release rates than BEX-c both under aerobic and hypoxic conditions, and (3) hypoxia induced apoptosis in WIX-c but not in BEX-c. These observations suggested that the difference between BEX-c and WIX-c spheroids in fraction of hypoxic cells resulted partly from differences in cell energy metabolism and partly from a difference in capacity to retain viability under hypoxic stress. The induction of apoptosis by hypoxia was identified as a phenomenon which has an important influence on the magnitude of the fraction of

  4. Physics and radiobiology of nuclear medicine

    CERN Document Server

    Saha, Gopal B

    2013-01-01

    The Fourth Edition of Dr. Gopal B. Saha’s Physics and Radiobiology of Nuclear Medicine was prompted by the need to provide up-to-date information to keep pace with the perpetual growth and improvement in the instrumentation and techniques employed in nuclear medicine since the last edition published in 2006. Like previous editions, the book is intended for radiology and nuclear medicine residents to prepare for the American Board of Nuclear Medicine, American Board of Radiology, and American Board of Science in Nuclear Medicine examinations, all of which require a strong physics background. Additionally, the book will serve as a textbook on nuclear medicine physics for nuclear medicine technologists taking the Nuclear Medicine Technology Certification Board examination.

  5. Amchitka radiobiological program progress report, January 1976--December 1976

    International Nuclear Information System (INIS)

    Nelson, V.A.; Seymour, A.H.

    1977-05-01

    The Amchitka Radiobiological Program is a continuing program to collect biological and environmental samples for radiometric analyses. Results of analyses for samples collected during 1976 include gamma-emitting radionuclides in air filters, freshwater, birds, lichens, marine algae, marine invertebrates, fish, aufwuchs, and freshwater moss and plants; 90 Sr in rats, birds, and soil; 239 240 Pu in sand, soil, marine algae and fish; and tritium ( 3 H) in seawater, freshwater, and biological organisms

  6. Claudius Regaud (1870-1940): A pioneer of radiobiology and radiotherapy

    International Nuclear Information System (INIS)

    Foray, N.

    2012-01-01

    Born in 1870, Claudius Regaud was a pioneer of radiobiology and radiotherapy. As histologist, he developed a new staining technique that allowed him to describe in detail all the reproduction system of a number of animal models. As radio-biologist, he contradicted the interpretations of Tribondeau and Bergonie about relationships between cell proliferation and radiosensitivity. In 1908, he suggested that chromatin was the main target of radiation. As physician, he defined the first bases of anti-cancer radiation treatments and treated patients suffering from incurable cancer from 1911. As military doctor, he organized war hospitals by creating multidisciplinary teams for the surgery of hurts. Organizer, he was one of the founders of the League against Cancer. As radiotherapist and brachy-therapist, he contributed to make Institut Curie an international reference center for research and teaching, with nearly a thousand treated patients. As globe-trotter, he was at the origin of the creation of numerous worldwide radiotherapy and radiobiology centers. He died in December 1940 and let an impressive but still mis-known scientific heritage. A re-reading of the familial archives and the Regaud Fund of Institut Curie is the occasion to remind the contribution of Regaud. (authors)

  7. A radiobiological review on melatonin. A novel radioprotector

    International Nuclear Information System (INIS)

    Shirazi Hosseinidokht, A.

    2007-01-01

    Complete text of publication follows. For the sake of improvement in radiation therapy, radiobiology plays a crucial role through explaining observed phenomena, and suggesting improvements to existing therapies. Due to the damaging effects of ionizing radiation, radiobiologists have long been interested in identifying novel, nontoxic, effective, and convenient compounds to protect humans against radiation induced normal tissue injuries. Melatonin (N-acetyl-5-methoxytryptamine), the chief secretory product of the pineal gland in the brain, has been documented to ameliorate the oxidative injuries due to ionizing radiation. This article reviews different features that make melatonin a potentially useful radioprotector. Moreover, based on radiobiological models we hypothesize that melatonin may postpone the saturation of repair enzymes which leads to repairing more induced damage by repair system and more importantly allows the use of higher doses of radiation during radiotherapy to get a better therapeutic ratio. The implications of the accumulated observations suggest by virtue of melatonin's radioprotective and anticancer effects; it is time to use it as a radioprotector both for radiation workers and patients suffering from cancer either alone for cancer inhibition or in combination with traditional radiotherapy for getting a favorable efficacy/toxicity ratio during the treatment. Although compelling evidence suggests that melatonin may be effective for a variety of disorders, the optimum dose of melatonin for human radioprotection is yet to be determined by further research. We propose that, in the future melatonin improve therapeutic ratio in radiation oncology.

  8. Mixed-field GCR Simulations for Radiobiological Research using Ground Based Accelerators

    Science.gov (United States)

    Kim, Myung-Hee Y.; Rusek, Adam; Cucinotta, Francis

    Space radiation is comprised of a large number of particle types and energies, which have differential ionization power from high energy protons to high charge and energy (HZE) particles and secondary neutrons produced by galactic cosmic rays (GCR). Ground based accelerators such as the NASA Space Radiation Laboratory (NSRL) at Brookhaven National Laboratory (BNL) are used to simulate space radiation for radiobiology research and dosimetry, electronics parts, and shielding testing using mono-energetic beams for single ion species. As a tool to support research on new risk assessment models, we have developed a stochastic model of heavy ion beams and space radiation effects, the GCR Event-based Risk Model computer code (GERMcode). For radiobiological research on mixed-field space radiation, a new GCR simulator at NSRL is proposed. The NSRL-GCR simulator, which implements the rapid switching mode and the higher energy beam extraction to 1.5 GeV/u, can integrate multiple ions into a single simulation to create GCR Z-spectrum in major energy bins. After considering the GCR environment and energy limitations of NSRL, a GCR reference field is proposed after extensive simulation studies using the GERMcode. The GCR reference field is shown to reproduce the Z and LET spectra of GCR behind shielding within 20 percents accuracy compared to simulated full GCR environments behind shielding. A major challenge for space radiobiology research is to consider chronic GCR exposure of up to 3-years in relation to simulations with cell and animal models of human risks. We discuss possible approaches to map important biological time scales in experimental models using ground-based simulation with extended exposure of up to a few weeks and fractionation approaches at a GCR simulator.

  9. Radiobiological heterogeneity of leukemic lymphocyte precursors from acute lymphoblastic leukemia patients

    International Nuclear Information System (INIS)

    Uckun, F.M.; Kim, T.H.; Ramsay, N.C.; Min, W.S.; Song, C.W.

    1989-01-01

    The report outlines the authors' findings on the radiobiological features of leukemic lymphocyte precursors from acute lymphoblastic leukemia (ALL) patients. A marked heterogeneity existed between different cell lines, with a remarkable radioresistance and repair capacity in some ALL patients and an acute radiosensitivity in the absence of a detectable repair capacity in others. (U.K.)

  10. Harmonization of radiobiological assays: why and how?

    International Nuclear Information System (INIS)

    Prasanna, Pataje G.

    2014-01-01

    The International Atomic Energy Agency has made available a technical manual for cytogenetic biodosimetry assays (dicentric chromosome aberration (DCA) and cytokinesis-block micronucleus (CBMN) assays) used for radiation dose assessment in radiation accidents. The International Standardization Organization, which develops standards and guidelines, also provides an avenue for laboratory accreditation, has developed guidelines and recommendations for performing cytogenetic biodosimetry assays. Harmonization of DCA and CBMN assays, has improved their accuracy. Double-blinded inter-laboratory comparison studies involving several networks have further validated DCA and CBMN assays and improved the confidence in their potential use for radiation dose assessment in mass casualties. This kind of international harmonization is lacking for pre-clinical radiobiology assays. The widely used pre-clinical assays that are relatively important to set stage for clinical trials include clonogenic assays, flow-cytometry assays, apoptotic assays, and tumor regression and growth delay assays. However, significant inter-laboratory variations occur with respect to data among laboratories. This raises concerns on the reliability and reproducibility of preclinical data that drives further development and translation. Lack of reproducibility may stem from a variety of factors such as poor scientist training, less than optimal experimental design, inadequate description of methodology, and impulse to publish only the positive data etc. Availability of technical manuals, standard operating procedures, accreditation avenues for laboratories performing such assays, inter-laboratory comparisons, and use of standardized protocols are necessary to enhance reliability and reproducibility. Thus, it is important that radiobiological assays are harmonized for laboratory protocols to ensure successful translation of pre-clinical research on radiation effect modulators to help design clinic trials with

  11. Comparative study on fast neutrons radiobiological effect on Chinese hamster cells in culture depending on regime of irradiation

    International Nuclear Information System (INIS)

    Elisova, T.V.; Feoktistova, T.P.; Stavrakova, N.M.

    1988-01-01

    Comparative study of regularities of fast neutron radiobiological effect on Chinese hamster cells in culture under pulse and statistic irradiation regimes that was estimated by reproductive death of cells and induced frequency of resistence mutations to 6-tioguanine is carried out. It is stated that with the dose rate increase approximately by 6 orders radiobiological efficiency of fast neutrons decreases. It is suggested that one of the causes of decreasing pulse irradiation efficiency are processes on radiation-chemical level. 9 refs.; 3 figs

  12. Radiobiological studies using gamma and x rays.

    Energy Technology Data Exchange (ETDEWEB)

    Potter, Charles Augustus; Longley, Susan W.; Scott, Bobby R.; Lin, Yong; Wilder, Julie; Hutt, Julie A.; Padilla, Mabel T.; Gott, Katherine M.

    2013-02-01

    There are approximately 500 self-shielded research irradiators used in various facilities throughout the U.S. These facilities use radioactive sources containing either 137Cs or 60Co for a variety of biological investigations. A report from the National Academy of Sciences[1] described the issues with security of particular radiation sources and the desire for their replacement. The participants in this effort prepared two peer-reviewed publications to document the results of radiobiological studies performed using photons from 320-kV x rays and 137Cs on cell cultures and mice. The effectiveness of X rays was shown to vary with cell type.

  13. Radiation biophysicl study of biological molecules. Progress report, February 1, 1975--June 30, 1976

    International Nuclear Information System (INIS)

    Fluke, D.J.

    1976-01-01

    Progress is reported on the following research projects: direct action target investigation of molecular weights of enzymes exposed to fast electrons; direct action gamma radiation dosimetry with T 1 bacteriophage; uv radiation sensitivity of T 1 bacteriophage on various host strains of E. coli; temperature dependence of uv radiation direct action on dry T 1 bacteriophage; investigation of light and temperature effects during incubation of T 1 bacteriophage exposed to fast electrons; test of superoxide anion as a radiation intermediate in cellular radiobiology; uv action spectra related to error-prone repair; uv-reactivation experiments with T 1 and lambda bacteriophages; and split-dose uv mutagenesis in E. coli

  14. AFRRI (Armed Forces Radiobiology Research Institute) Reports, October, November and December 1987.

    Science.gov (United States)

    1988-03-01

    pulsive motility (7), diarrhea (10), anorexia (29, present ported by the Armed Forces Radiobiology Research Institute, Defense Nuclear Agency, under...there was no significant interaction be- food than the rats with VMH lesions alone this was teen time and treatment groups (h’= 1.74. df= 12. not a

  15. Design study of the ESS-Bilbao 50 MeV proton beam line for radiobiological studies

    Energy Technology Data Exchange (ETDEWEB)

    Huerta-Parajon, M., E-mail: mhuerta@essbilbao.org; Martinez-Ballarin, R., E-mail: rmartinez@essbilbao.org; Abad, E., E-mail: eabad@essbilbao.org

    2015-02-01

    The ESS-Bilbao proton accelerator facility has been designed fulfilling the European Spallation Source (ESS) specifications to serve as the Spanish contribution to the ESS construction. Furthermore, several applications of the ESS-Bilbao proton beam are being considered in order to contribute to the knowledge in the field of radiobiology, materials and aerospace components. Understanding of the interaction of radiation with biological systems is of vital importance as it affects important applications such as cancer treatment with ion beam therapy among others. ESS-Bilbao plans to house a facility exclusively dedicated to radiobiological experiments with protons up to 50 MeV. Beam line design, optimisation and initial calculations of flux densities and absorbed doses were undertaken using the Monte Carlo simulation package FLUKA. A proton beam with a flux density of about 10{sup 6} protons/cm{sup 2} s reaches the water sample with a flat lateral distribution of the dose. The absorbed dose at the pristine Bragg peak calculated with FLUKA is 2.4 ± 0.1 Gy in 1 min of irradiation time. This value agrees with the clinically meaningful dose rates, i.e. around 2 Gy/min, used in hadrontherapy. Optimisation and validation studies in the ESS-Bilbao line for radiobiological experiments are detailed in this article.

  16. Radiobiologically based treatment plan evaluation for prostate seed implants

    Directory of Open Access Journals (Sweden)

    Sotirios Stathakis

    2011-07-01

    Full Text Available Purpose: Accurate prostate low dose-rate brachytherapy treatment plan evaluation is important for future care decisions. Presently, an evaluation is based on dosimetric quantifiers for the tumor and organs at risk. However, these do not account for effects of varying dose-rate, tumor repopulation and other biological effects. In this work, incorporation of the biological response is used to obtain more clinically relevant treatment plan evaluation.Material and methods: Eleven patients were evaluated. Each patient received a 145 Gy implant. Iodine-125 seeds were used and the treatment plans were created on the Prowess system. Based on CT images the post-implant plan was created. In the post-plan, the tumor, urethra, bladder and rectum were contoured. The biologically effective dose was used to determine the tumor control probability and the normal tissue complication probabilities for the urethra, bladder, rectum and surrounding tissue. Results: The average tumor control probability and complication probabilities for the urethra, bladder, rectum and surrounding tissue were 99%, 29%, 0%, 12% and 6%, respectively. These measures provide a simpler means for evaluation and since they include radiobiological factors, they provide more reliable estimation of the treatment outcome. Conclusions: The goal of this work was to create more clinically relevant prostate seed-implant evaluation by incorporating radiobiological measures. This resulted in a simpler descriptor of treatment plan quality and was consistent with patient outcomes.

  17. LDR vs. HDR brachytherapy for localized prostate cancer: the view from radiobiological models.

    Science.gov (United States)

    King, Christopher R

    2002-01-01

    Permanent LDR brachytherapy and temporary HDR brachytherapy are competitive techniques for clinically localized prostate radiotherapy. Although a randomized trial will likely never be conducted comparing these two forms of brachytherapy, a comparative radiobiological modeling analysis proves useful in understanding some of their intrinsic differences, several of which could be exploited to improve outcomes. Radiobiological models based upon the linear quadratic equations are presented for fractionated external beam, fractionated (192)Ir HDR brachytherapy, and (125)I and (103)Pd LDR brachytherapy. These models incorporate the dose heterogeneities present in brachytherapy based upon patient-derived dose volume histograms (DVH) as well as tumor doubling times and repair kinetics. Radiobiological parameters are normalized to correspond to three accepted clinical risk factors based upon T-stage, PSA, and Gleason score to compare models with clinical series. Tumor control probabilities (TCP) for LDR and HDR brachytherapy (as monotherapy or combined with external beam) are compared with clinical bNED survival rates. Predictions are made for dose escalation with HDR brachytherapy regimens. Model predictions for dose escalation with external beam agree with clinical data and validate the models and their underlying assumptions. Both LDR and HDR brachytherapy achieve superior tumor control when compared with external beam at conventional doses (LDR brachytherapy as boost achieves superior tumor control than when used as monotherapy. Stage for stage, both LDR and current HDR regimens achieve similar tumor control rates, in agreement with current clinical data. HDR monotherapy with large-dose fraction sizes might achieve superior tumor control compared with LDR, especially if prostate cancer possesses a high sensitivity to dose fractionation (i.e., if the alpha/beta ratio is low). Radiobiological models support the current clinical evidence for equivalent outcomes in localized

  18. SU-F-J-11: Radiobiologically Optimized Patient Localization During Prostate External Beam Localization

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Y; Gardner, S; Liu, C; Zhao, B; Wen, N; Brown, S; Chetty, I [Henry Ford Health System, Detroit, MI (United States)

    2016-06-15

    Purpose: To present a novel positioning strategy which optimizes radiation delivery with radiobiological response knowledge, and to evaluate its application during prostate external beam radiotherapy. Methods: Ten patients with low or intermediate risk prostate cancer were evaluated retrospectively in this IRB-approved study. For each patient, a VMAT plan was generated on the planning CT (PCT) to deliver 78 Gy in 39 fractions with PTV = prostate + 7 mm margin, except for 5mm in the posterior direction. Five representative pretreatment CBCT images were selected for each patient, and prostate, rectum, and bladder were delineated on all CBCT images. Each CBCT was auto-registered to the corresponding PCT. Starting from this auto-matched position (AM-position), a search for optimal treatment position was performed utilizing a score function based on radiobiological and dosimetric indices (D98-DTV, NTCP-rectum, and NTCP-bladder) for the daily target volume (DTV), rectum, and bladder. DTV was defined as prostate + 4 mm margin to account for intra-fraction motion as well as contouring variability on CBCT. We termed the optimal treatment position the radiobiologically optimized couch shift position (ROCS-position). Results: The indices, averaged over the 10 patients’ treatment plans, were (mean±SD): 77.7±0.2 Gy (D98-PTV), 12.3±2.7% (NTCP-rectum), and 53.2±11.2% (NTCP-bladder). The corresponding values calculated on all 50 CBCT images at the AM-positions were 72.9±11.3 Gy (D98-DTV), 15.8±6.4% (NTCP-rectum), and 53.0±21.1% (NTCP-bladder), respectively. In comparison, calculated on CBCT at the ROCS-positions, the indices were 77.0±2.1 Gy (D98-DTV), 12.1±5.7% (NTCP-rectum), and 60.7±16.4% (NTCP-bladder). Compared to autoregistration, ROCS-optimization recovered dose coverage to target volume and lowered the risk to rectum. Moreover, NTCPrectum for one patient remained high after ROCS-optimization and therefore could potentially benefit from adaptive planning

  19. Radiobiological research at its best. Does a low radiation dose involve risks?

    International Nuclear Information System (INIS)

    Baatout, S.; Jacquet, P.; Derradji, H.

    2011-01-01

    Radiotherapy, radiation protection, nuclear medicine, etc.: there is a growing interest in radio(bio)logy in the health care sector. The number of medical treatments with ionising radiation per year will increase even more. It is therefore increasingly important to closely monitor the possible harmful effects of low radiation doses.

  20. Cytokine modulation by glucocorticoids: mechanisms and actions in cellular studies.

    Science.gov (United States)

    Brattsand, R; Linden, M

    1996-01-01

    cascades, this means that steroid treatment can block expression of the subsequent cytokines. The blocked cytokine activity does not depend on a reduced cytokine receptor expression; in fact available in vitro investigations show that while the cytokine expression is blunted, its receptor is upregulated. The cellular studies presented here may represent the maximum potential of steroids to modulate cytokine expression in human mononuclear cells. It remains to be determined by clinical-experimental studies how effective cytokine modulation can be achieved in situ in inflamed bowel by systemic or by topical steroid therapy. Such studies may also answer whether a blocked cytokine production/action is the key or just a secondary mechanism behind the unique efficacy of steroids in active inflammatory bowel disease.

  1. Defining the action spectrum of potential PGC-1α activators on a mitochondrial and cellular level in vivo.

    Science.gov (United States)

    Hofer, Annette; Noe, Natalie; Tischner, Christin; Kladt, Nikolay; Lellek, Veronika; Schauß, Astrid; Wenz, Tina

    2014-05-01

    Previous studies have demonstrated a therapeutic benefit of pharmaceutical PGC-1α activation in cellular and murine model of disorders linked to mitochondrial dysfunction. While in some cases, this effect seems to be clearly associated with boosting of mitochondrial function, additional alterations as well as tissue- and cell-type-specific effects might play an important role. We initiated a comprehensive analysis of the effects of potential PGC-1α-activating drugs and pharmaceutically targeted the PPAR (bezafibrate, rosiglitazone), AMPK (AICAR, metformin) and Sirt1 (resveratrol) pathways in HeLa cells, neuronal cells and PGC-1α-deficient MEFs to get insight into cell type specificity and PGC-1α dependence of their working action. We used bezafibrate as a model drug to assess the effect on a tissue-specific level in a murine model. Not all analyzed drugs activate the PGC pathway or alter mitochondrial protein levels. However, they all affect supramolecular assembly of OXPHOS complexes and OXPHOS protein stability. In addition, a clear drug- and cell-type-specific influence on several cellular stress pathways as well as on post-translational modifications could be demonstrated, which might be relevant to fully understand the action of the analyzed drugs in the disease state. Importantly, the effect on the activation of mitochondrial biogenesis and stress response program upon drug treatment is PGC-1α dependent in MEFs demonstrating not only the pleiotropic effects of this molecule but points also to the working mechanism of the analyzed drugs. The definition of the action spectrum of the different drugs forms the basis for a defect-specific compensation strategy and a future personalized therapeutic approach.

  2. A comparison of physically and radiobiologically based optimization for IMRT

    International Nuclear Information System (INIS)

    Jones, Lois; Hoban, Peter

    2002-01-01

    Many optimization techniques for intensity modulated radiotherapy have now been developed. The majority of these techniques including all the commercial systems that are available are based on physical dose methods of assessment. Some techniques have also been based on radiobiological models. None of the radiobiological optimization techniques however have assessed the clinically realistic situation of considering both tumor and normal cells within the target volume. This study considers a ratio-based fluence optimizing technique to compare a dose-based optimization method described previously and two biologically based models. The biologically based methods use the values of equivalent uniform dose calculated for the tumor cells and integral biological effective dose for normal cells. The first biologically based method includes only tumor cells in the target volume while the second considers both tumor and normal cells in the target volume. All three methods achieve good conformation to the target volume. The biologically based optimization without the normal tissue in the target volume shows a high dose region in the center of the target volume while this is reduced when the normal tissues are also considered in the target volume. This effect occurs because the normal tissues in the target volume require the optimization to reduce the dose and therefore limit the maximum dose to that volume

  3. Research trends in radiobiology since 40 years. a new approach: the enzymatic repair function of DNA, internal factor in evolution of biological systems under irradiation

    International Nuclear Information System (INIS)

    Mouton, R.

    1968-01-01

    In the first part of the report, the author attempts to draw an historical scheme of successive research working hypotheses in radiobiology since 1924. Less than a generation ago the effect of radiation exposure were viewed as being direct, immediate, irreparable and unmodifiable. Now it is generally accepted that radiation lesion can also be indirect, delayed, reparable and often modified with appropriate chemical or biochemical treatment. It was however in 1962-1964 that came the decisive breakthrough in radiobiology with the discovery that the cell possesses a natural active self-defense mechanism against whatever stress would affect the integrity of the genetic message contained in the DNA structure itself. The existence of what could be considered as a fourth DNA function i.e. self-repair by enzymatic action under genetic control-brings at least to radiobiology the missing molecular biology basis it needed to get out of its 'phenomenological night' after abandon of the generalization of Lea's theory through lack of experimental evidence. In the second part, which is a prospective one, the author tries to set an enlarged synthesis considering the possible role of DNA repair system not only in cell survival - in presence or absence of dose modifiers or mutagens - but also in the artificial and natural evolution of biological system exposed to sub-lethal doses of radiation. Most recent data from the literature fit well with what must be still considered as a general working hypothesis. Studies dealing with phenotypic and genotypic characters linked with the acquisition of gamma and UV radiation resistance in 'Escherichia coli K12' has been started by the author, in collaboration with O. Tremeau, in order to bring a new experimental contribution in this respect. (author) [fr

  4. Relationships Between Rectal Wall Dose-Volume Constraints and Radiobiologic Indices of Toxicity for Patients With Prostate Cancer

    International Nuclear Information System (INIS)

    Marzi, Simona; Arcangeli, Giorgio; Saracino, Bianca; Petrongari, Maria G.; Bruzzaniti, Vicente; Iaccarino, Giuseppe; Landoni, Valeria; Soriani, Antonella; Benassi, Marcello

    2007-01-01

    Purpose: The purpose of this article was to investigate how exceeding specified rectal wall dose-volume constraints impacts on the risk of late rectal bleeding by using radiobiologic calculations. Methods and Materials: Dose-volume histograms (DVH) of the rectal wall of 250 patients with prostate cancer were analyzed. All patients were treated by three-dimensional conformal radiation therapy, receiving mean target doses of 80 Gy. To study the main features of the patient population, the average and the standard deviation of the distribution of DVHs were generated. The mean dose , generalized equivalent uniform dose formulation (gEUD), modified equivalent uniform dose formulation (mEUD) 0 , and normal tissue complication probability (NTCP) distributions were also produced. The DVHs set was then binned into eight classes on the basis of the exceeding or the fulfilling of three dose-volume constraints: V 40 = 60%, V 50 = 50%, and V 70 = 25%. Comparisons were made between them by , gEUD, mEUD 0 , and NTCP. Results: The radiobiologic calculations suggest that late rectal toxicity is mostly influenced by V 70 . The gEUD and mEUD 0 are risk factors of toxicity always concordant with NTCP, inside each DVH class. The mean dose, although a reliable index, may be misleading in critical situations. Conclusions: Both in three-dimensional conformal radiation therapy and particularly in intensity-modulated radiation therapy, it should be known what the relative importance of each specified dose-volume constraint is for each organ at risk. This requires a greater awareness of radiobiologic properties of tissues and radiobiologic indices may help to gradually become aware of this issue

  5. Radiobiology at GANIL: local project and others fields studied

    International Nuclear Information System (INIS)

    Anon.

    2001-01-01

    This article reviews the research that is led in the field of radiobiology using heavy ions at Ganil. Our first studies with heavy ions were mainly focused on chromosome rearrangements induced in irradiated human cells. We analyzed R-banded chromosome rearrangements in human lymphocytes irradiated with several ions having a wide range of linear energy transfer (LET). Damage increased with the fluence and LET but at the higher LET, damage decreased for fluences above 10 7 particles/cm 2 . Chromosome rearrangements of high complexity involve several breaks. DNA strand breaks are concentrated in localized areas and their complexity is greatly increased by high-LET radiations. Our study was mainly qualitative and we showed a clear shift and dispersion of comet distribution towards high tail moments when particle LET and fluence increased. The higher the LET, the greater the level of DNA breaks observed for the same fluence. Gamma rays were more effective in producing DNA breaks than all the ions, at least in the lower dose range. In addition to early damage, high-LET irradiation also induces delayed lesions, and genomic instability occurs after many generations in the progeny of irradiated cells. We observed delayed chromosome instability on human dermis fibroblasts exposed to heavy ions, neon, argon, and lead but not after gamma rays. Various fields of radiobiology are now explored by different research groups. One of the studies aims to detect locally multiple damage sites (LMDS) formed in DNA after exposure to heavy ions. (A.C.)

  6. Radioprotective action of endoneous and exogenous natural compounds

    International Nuclear Information System (INIS)

    Del Mastro, N.L.

    1991-04-01

    In last years at the Radiobiology Division of our Institute several studies have been performed to determine the radioprotective capacity of some natural products from microbial, vegetal or endogenous origin. This substances have been chosen for some of their specific biological characteristics, among them: immunoestimulating (bacillus of Calmette-Guerin, Corynebacterium parvum), anti-inflammatory (Cordia verbanacea), anti-carcinogenic and anti-oxidant ones (α-tocopherol). Assays were performed using albino mice previously injected intraperitoneally with those agents and then irradiated with lethal doses of sup(60)Co gamma radiation. Survival and body weight curves after irradiation have been studied during 30 days comparing to normal controls. Depending on the specific properties of tested substances the induction of splenomegalia and the behavior of peritoneal cellularity were concomitantly analyzed. (author)

  7. Cellular function of neuropathy target esterase in lysophosphatidylcholine action

    International Nuclear Information System (INIS)

    Vose, Sarah C.; Fujioka, Kazutoshi; Gulevich, Alex G.; Lin, Amy Y.; Holland, Nina T.; Casida, John E.

    2008-01-01

    Neuropathy target esterase (NTE) plays critical roles in embryonic development and maintenance of peripheral axons. It is a secondary target of some organophosphorus toxicants including analogs of insecticides and chemical warfare agents. Although the mechanistic role of NTE in vivo is poorly defined, it is known to hydrolyze lysophosphatidylcholine (LPC) in vitro and may protect cell membranes from cytotoxic accumulation of LPC. To determine the cellular function of NTE, Neuro-2a and COS-7 cells were transfected with a full-length human NTE-containing plasmid yielding recombinant NTE (rNTE). We find the same inhibitor sensitivity and specificity profiles for rNTE assayed with LPC or phenyl valerate (a standard NTE substrate) and that this correlation extends to the LPC hydrolases of human brain, lymphocytes and erythrocytes. All of these LPC hydrolases are therefore very similar to each other in respect to a conserved inhibitor binding site conformation. NTE is expressed in brain and lymphocytes and contributes to LPC hydrolase activities in these tissues. The enzyme or enzymes responsible for erythrocyte LPC hydrolase activity remain to be identified. We also show that rNTE protects Neuro-2a and COS-7 cells from exogenous LPC cytotoxicity. Expression of rNTE in Neuro-2a cells alters their phospholipid balance (analyzed by liquid chromatography-mass spectrometry with single ion monitoring) by lowering LPC-16:0 and LPC-18:0 and elevating glycerophosphocholine without a change in phosphatidylcholine-16:0/18:1 or 16:0/18:2. NTE therefore serves an important function in LPC homeostasis and action

  8. 5. workshop on heavy charged particles in biology and medicine. Book of abstracts

    International Nuclear Information System (INIS)

    1995-08-01

    This book contains about 90% of the abstracts of the papers presented at the workshop. The headings were as follows: DNA, mutations and chromosomal aberrations, cellular radiobiology, modelling in radiobiology, space research, clinical radiobiology, status reports of heavy ion radiotherapy, dosimetry and instrumentation and finally, 3-D-planning and clinical indications. (MG)

  9. Optimization in brachytherapy with the implementation of Radiobiology; Optimizacion en Braquiterapia con la implementacion de la Radiobiologia

    Energy Technology Data Exchange (ETDEWEB)

    Duran, M.P.; Bourel, V.J.; Rodriguez, I.; Torre, M. de la; Caneva, S. [Braqui S.R.L. Viamonte 1861, Buenos Aires (Argentina)

    1998-12-31

    In the brachytherapy planning treatments with High dose rates (HDR), the optimization algorithms used are based in dosimetric considerations and/or geometric ones, ignoring the radiobiological response of the tissue treated. In this work we wish to show the implementation of radiobiological concepts in the optimization. Assuming that the subtiles differences that result in the dose distribution among the different optimization models which are not visible in an isodose plane, it is studied how is classically make it , the quality implant through natural histograms about dose volumes and the resulting parameters. Also is studied the necrosis probability which may be caused by the choice of some optimization model, allowing with this the choice of the best implant. (Author)

  10. Radiobiological influence of megavoltage electron pulses of ultra-high pulse dose rate on normal tissue cells.

    Science.gov (United States)

    Laschinsky, Lydia; Karsch, Leonhard; Leßmann, Elisabeth; Oppelt, Melanie; Pawelke, Jörg; Richter, Christian; Schürer, Michael; Beyreuther, Elke

    2016-08-01

    Regarding the long-term goal to develop and establish laser-based particle accelerators for a future radiotherapeutic treatment of cancer, the radiobiological consequences of the characteristic short intense particle pulses with ultra-high peak dose rate, but low repetition rate of laser-driven beams have to be investigated. This work presents in vitro experiments performed at the radiation source ELBE (Electron Linac for beams with high Brilliance and low Emittance). This accelerator delivered 20-MeV electron pulses with ultra-high pulse dose rate of 10(10) Gy/min either at the low pulse frequency analogue to previous cell experiments with laser-driven electrons or at high frequency for minimizing the prolonged dose delivery and to perform comparison irradiation with a quasi-continuous electron beam analogue to a clinically used linear accelerator. The influence of the different electron beam pulse structures on the radiobiological response of the normal tissue cell line 184A1 and two primary fibroblasts was investigated regarding clonogenic survival and the number of DNA double-strand breaks that remain 24 h after irradiation. Thereby, no considerable differences in radiation response were revealed both for biological endpoints and for all probed cell cultures. These results provide evidence that the radiobiological effectiveness of the pulsed electron beams is not affected by the ultra-high pulse dose rates alone.

  11. Radiobiological influence of megavoltage electron pulses of ultra-high pulse dose rate on normal tissue cells

    International Nuclear Information System (INIS)

    Laschinsky, Lydia; Karsch, Leonhard; Schuerer, Michael; Lessmann, Elisabeth; Beyreuther, Elke; Oppelt, Melanie; Pawelke, Joerg; Richter, Christian

    2016-01-01

    Regarding the long-term goal to develop and establish laser-based particle accelerators for a future radiotherapeutic treatment of cancer, the radiobiological consequences of the characteristic short intense particle pulses with ultra-high peak dose rate, but low repetition rate of laser-driven beams have to be investigated. This work presents in vitro experiments performed at the radiation source ELBE (Electron Linac for beams with high Brilliance and low Emittance). This accelerator delivered 20-MeV electron pulses with ultra-high pulse dose rate of 10"1"0 Gy/min either at the low pulse frequency analogue to previous cell experiments with laser-driven electrons or at high frequency for minimizing the prolonged dose delivery and to perform comparison irradiation with a quasi-continuous electron beam analogue to a clinically used linear accelerator. The influence of the different electron beam pulse structures on the radiobiological response of the normal tissue cell line 184A1 and two primary fibroblasts was investigated regarding clonogenic survival and the number of DNA double-strand breaks that remain 24 h after irradiation. Thereby, no considerable differences in radiation response were revealed both for biological endpoints and for all probed cell cultures. These results provide evidence that the radiobiological effectiveness of the pulsed electron beams is not affected by the ultra-high pulse dose rates alone. (orig.)

  12. Understanding the cellular mode of action of vernakalant using a computational model: answers and new questions

    Directory of Open Access Journals (Sweden)

    Loewe Axel

    2015-09-01

    Full Text Available Vernakalant is a new antiarrhythmic agent for the treatment of atrial fibrillation. While it has proven to be effective in a large share of patients in clinical studies, its underlying mode of action is not fully understood. In this work, we aim to link experimental data from the subcellular, tissue, and system level using an in-silico approach. A Hill’s equation-based drug model was extended to cover the frequency dependence of sodium channel block. Two model variants were investigated: M1 based on subcellular data and M2 based on tissue level data. 6 action potential (AP markers were evaluated regarding their dose, frequency and substrate dependence. M1 comprising potassium, sodium, and calcium channel block reproduced the reported prolongation of the refractory period. M2 not including the effects on potassium channels reproduced reported AP morphology changes on the other hand. The experimentally observed increase of ERP accompanied by a shortening of APD90 was not reproduced. Thus, explanations for the drug-induced changes are provided while none of the models can explain the effects in their entirety. These results foster the understanding of vernakalant’s cellular mode of action and point out relevant gaps in our current knowledge to be addressed in future in-silico and experimental research on this aspiring antiarrhythmic agent.

  13. A note on modeling of tumor regression for estimation of radiobiological parameters

    International Nuclear Information System (INIS)

    Zhong, Hualiang; Chetty, Indrin

    2014-01-01

    Purpose: Accurate calculation of radiobiological parameters is crucial to predicting radiation treatment response. Modeling differences may have a significant impact on derived parameters. In this study, the authors have integrated two existing models with kinetic differential equations to formulate a new tumor regression model for estimation of radiobiological parameters for individual patients. Methods: A system of differential equations that characterizes the birth-and-death process of tumor cells in radiation treatment was analytically solved. The solution of this system was used to construct an iterative model (Z-model). The model consists of three parameters: tumor doubling time T d , half-life of dead cells T r , and cell survival fraction SF D under dose D. The Jacobian determinant of this model was proposed as a constraint to optimize the three parameters for six head and neck cancer patients. The derived parameters were compared with those generated from the two existing models: Chvetsov's model (C-model) and Lim's model (L-model). The C-model and L-model were optimized with the parameter T d fixed. Results: With the Jacobian-constrained Z-model, the mean of the optimized cell survival fractions is 0.43 ± 0.08, and the half-life of dead cells averaged over the six patients is 17.5 ± 3.2 days. The parameters T r and SF D optimized with the Z-model differ by 1.2% and 20.3% from those optimized with the T d -fixed C-model, and by 32.1% and 112.3% from those optimized with the T d -fixed L-model, respectively. Conclusions: The Z-model was analytically constructed from the differential equations of cell populations that describe changes in the number of different tumor cells during the course of radiation treatment. The Jacobian constraints were proposed to optimize the three radiobiological parameters. The generated model and its optimization method may help develop high-quality treatment regimens for individual patients

  14. A comparative study of the radiobiologic risks from three different TMJ (temporary modular joint) radiographic techniques using a pan-tomographic system

    International Nuclear Information System (INIS)

    Chilvarquer, Israel.

    1992-01-01

    The aim of this study was the obtention of the absorbed doses to critical organs for evaluating and comparing the radiobiologic risks from three different TMJ radiographic techniques, using a pantomographic system, utilizing a combination of rare-earth screens to fast films. The compared techniques were the conventional panoramic technique, the Manufacture's recommended technique for TMJ and the Chilvarquer's technique. The absorber doses were measured by exposing a phantom, fitted with fluoride TLD in fourteen sites distributed at the Thyroid, Pituitary, Salivary glands sites distributed at the Thyroid, Pituitary, Salivary glands and at the bone marrow. The radiobiologic risks were calculated using the UNSCEAR 34 (1977), and the fatal cancer incidence for age and sex was calculated using the ICRP 29 (1977). Based on the obtained data, it was concluded that the Chilvarquer's technique induced the lowest absorbed doses and the estimated radiobiologic risks were lower than a cancer per a million of examinations. (author). 108 refs., 19 figs., 14 tabs

  15. SU-E-T-194: From Dicom-RT to Radiobiological Dose Metrics in 5 Minutes

    Energy Technology Data Exchange (ETDEWEB)

    Whelan, B; Holloway, L

    2014-06-01

    Purpose: To develop a flexible and standalone framework for batch calculation of radiobiological dose metrics from Dicom-RT. Methods: Software has been developed which allows (1) The calculation of DVH data from DICOM dose and structure files (DVHgenerator), (2) Calculation of a wide range of radiobiological metrics from this data (CompPlanGui). Both these tools are run via graphical user interface (GUI), making them fast and simple. Part 1 is a new tool which has not previously been published, whilst part 2 is a GUI overlay for the previously published software ‘Comp-Plan’ (Holloway et. al., Medical Dosimetry, 2012), previously reliant on command line interface. The time taken for an experienced user to evaluate a test case of 6 plans with and without CompPlanGUI was quantified. Results: The DVH-generator has been found to be faster, more robust and require far less physical memory then using alternative software solutions for the same purpose. The Comp Plan GUI significantly reduces the amount of time required to set up a base directory, eliminates code crashes arising from typographical errors, and renders the code far more accessible to non-expert users. It took an experienced user of the code around 3 minutes to set up a base directory of 6 plans compared around 8 minutes without, indicating that using CompPlanGUI reduced setup time by over 50%. Conclusion: A standalone GUI based framework has developed which allows for the batch calculation of radiobiological dose metrics directly from Dicom-RT files. As with the original code, this work will be made freely available on request, as well as via matlab file exchange.

  16. Radon: current challenges in cellular radiobiology

    International Nuclear Information System (INIS)

    Brenner, D.J.

    1992-01-01

    Most of what is known about the hazards of radon daughters comes from epidemiological studies of miners. There are a few well defined areas in which in vitro research can complement such studies: More data on the relative effects of differing energy (LET) α-particles would help: (1) understand the significance of the depth of sensitive cells in the bronchial epithelium-which varies between individuals, as well as between smokers and non-smokers, and between miners and non-miners; (2) understand the relative hazards of radon and thoron daughters. Reliable methods for predicting high LET responses from low LET response, would enable Japanese A-bomb survivor data to be applied with confidence. Understanding the effects of single-particle traversals of cells relative to multiple traversals could allow reliable extrapolation of epidemiological miner data to low exposures. A better understanding of the nature of the interaction between tobacco and radiation damage would help predict the effect of radon on non-smokers. (author)

  17. Installation of a flow cytometry facility and some applications in radiobiology

    International Nuclear Information System (INIS)

    Walsh, M.; Kellington, J.P.

    1988-01-01

    Flow cytometry has enormous potential in many areas of experimental pathology. Details of the installation and commissioning of a flow cytometer at the Harwell Laboratory are described. Following an explanation of the principles of flow cytometry, several applications to specific problems in radiobiology are discussed. Also included are results of some preliminary studies with the Harwell flow cytometer on samples such as blood, bone marrow, macrophages and cell cultures, and a discussion of future applications. (author)

  18. [From microdosimetry to nanodosimetry--the link between radiobiology and radiation physics].

    Science.gov (United States)

    Fu, Yuchuan; Li, Ping

    2014-06-01

    The link between micro- and macro-parameters for radiation interactions that take place in living biological systems is described in this paper. Meanwhile recent progress and development in microdosimetry and nanodosimetry are introduced, including the methods to measure and calculate these micro- or nano-parameters. The relationship between radiobiology and physical quantities in microdosimetry and nanodosimetry was presented. Both the current problems on their applications in radiation protection and radiotherapy and the future development direction are proposed.

  19. Biophysical and biomathematical adventures in radiobiology

    International Nuclear Information System (INIS)

    Scott, B.R.

    1991-01-01

    Highlights of my biophysical and biomathematical adventures in radiobiology is presented. Early adventures involved developing ''state-vector models'' for specific harmful effects (cell killing, life shortening) of exposure to radiation. More recent adventures led to developing ''hazard-function models'' for predicting biological effects (e.g., cell killing, mutations, tumor induction) of combined exposure to different toxicants. Hazard-function models were also developed for predicting harm to man from exposure to large radiation doses. Major conclusions derived from the modeling adventures are as follows: (1) synergistic effects of different genotoxic agents should not occur at low doses; (2) for exposure of the lung or bone marrow to large doses of photon radiation, low rates of exposure should be better tolerated than high rates; and (3) for some types of radiation (e.g., alpha particles and fission neutrons), moderate doses delivered at a low rate may be more harmful than the same dose given at a high rate. 53 refs., 7 figs

  20. Radiation oncology: radiobiological and physiological perspectives

    International Nuclear Information System (INIS)

    Awwad, H.K.

    1990-01-01

    This book deals with the normal tissue and tumor radiation-induced responses in terms of the underlying radiobiological and physiological process. Coverage includes the following topics: Functional test for normal tissue responses. Relation to the underlying target cell, Clinical structural end-points, e.g., increased lung density in CT-scan. Conditions and parameters of the LQ-model in clinical applications. An NSD-type of formalism is still clinically applicable. Clinical importance of the kinetics of recovery. The notion of normal tissue tolerance and tumor control. The steepness of the response curve. How accurate radiotherpy should be. The volume effect: clinical, biological and physiological perspectives. The tumor bed effect, residual damage and the problems of reirradiation. Radiation-induced perturbations of the immune response. Clinical consequences. Exploitation to a therapeutic benefit. Hypoxia in human solid tumors. Probing and methods of control. Growth of human tumors. Parameters, measurement and clinical implications. The dose-rate effect. The optimum use of low dose rate irradiation in human cancer

  1. Radiobiology 2000: advances in fundamental and clinical radiobiology. Programme and abstracts: 1st international congress of the South African Radiobiology Society (SARS) in conjunction with the South African Association of Physicists in Medicine and Biology (SAAPMB) and the University of Stellenbosch, 10-13 December 2000, Music Conservatoire, University of Stellenbosch

    International Nuclear Information System (INIS)

    2000-12-01

    Programme and abstracts of the 1st international congress of the South African Radiobiology Society, held in conjunction with the South African Association of Physicists in Medicine and Biology and the University of Stellenbosch, from 10-13 December 2000. This publication contain the abstracts of the forty-four papers and posters that were presented

  2. A detailed radiobiological and dosimetric analysis of biochemical outcomes in a case-control study of permanent prostate brachytherapy patients

    International Nuclear Information System (INIS)

    Butler, Wayne M.; Stewart, Renee R.; Merrick, Gregory S.

    2009-01-01

    The purpose of this study is to determine dosimetric and radiobiological predictors of biochemical control after recalculation of prostate implant dosimetry using updated AAPM Task Group 43 (TG-43) parameters and the radiobiological parameters recommended by TG-137. All biochemical failures among patients implanted with 125 I or 103 Pd sources between 1994 and March 2006 were matched 2:1 with nonfailure controls. The individual matching was by risk group, radionuclide, prescribed dose, and time of implant (one match before and one after the failed patient) resulting in a median follow-up of 10.9 years. Complete dose volume histogram (DVH) data were recalculated for all 55 cases and 110 controls after updating the original source strength by the retrospectively determined ratios of TG-43. Differential DVH data were acquired in 179 increments of prostate volume versus percentage prescribed dose. At each incremental dose level i, the biologically equivalent dose BED i , equivalent uniform dose EUD i , and tumor control probability TCP i were calculated from the implant dose plus any external beam delivered to the patient. Total BED, EUD, and TCP were then derived from the incremental values for comparison with single point dosimetric quality parameters and DVH-based averages. There was no significant difference between failures and controls in terms of total BED (143 vs 142 Gy), EUD (95 vs 94 Gy), or TCP (0.87 vs 0.89). Conditional logistic regression analysis factored out the matching variables and stratified the cohort into each case and its controls, but no radiobiological parameter was predictive of biochemical failure. However, there was a significant difference between radiobiological parameters of 125 I and 103 Pd due to less complete coverage of the target volume by the former isotope. The implant BED and TCP were highly correlated with the D 90 and natural prescription doses and a series of mean DVH-based doses such as the harmonic mean and expressions of the

  3. Conjunct action of gamma radiation and casiopeinas in two cellular types

    International Nuclear Information System (INIS)

    Ramos V, N.I.

    2006-01-01

    In Mexico the cancer occupies the second place in the causes of death and although already there are diverse useful treatments to attack this suffering, the search of new pharmaceuticals that present positive effect in the treatment of the cancer there is taken to the development of a group of substances called Casiopeinas. Its are coordination compounds constituted by a central atom of copper (Cu II) joined to organic ligands, with general condensed formula [Cu (NN)(ON)]NO 3 , or [Cu(NN)(OO)]NO 3 . Its present different cytotoxicity levels, as well as in vitro antineoplastic activity in diverse tissues derived of tumors. Even its ignore the mechanisms of it action, but one of them, it could be by generation of reactive species of oxygen (ERO), mediated by the metallic center that contain. Thinking of this possibility was carried out in vitro experiments, exposing lymphocytes or HeLa cells, to ionizing radiation, at two casiopeinas (Casiopeina llgly and the Casiopeina Ill-e-a) or the combination of both agents, in order to determine if the antineoplastic capacity of both types of treatments increase in conjunct action. To determine it its were carried out cytotoxicity tests by means of the differential dyeing of fluorescein diacetate and etidio bromide, in these the cells alive fluorescein in green color while the dead ones only the nucleus of red tinged. The genotoxicity was evaluated by means of the comet essay. The results hurtled that as much the casiopeinas as the radiation by separate don't present difference among both cellular types, probably due to the used method that only quantifies the damages at the moment and not to long term. And according to those treatments on the whole only to the concentrations and the doses more high it favors the additive effect due to an overproduction of free radicals that not can be neutralized. According to the genotoxicity, only proven for the radiation indicates that the HeLa cells presents a major number of cells with

  4. Proceedings of 6th International Microbeam Workshop/12th L.H. Gray Workshop Microbeam Probes of Cellular Radiation Response

    International Nuclear Information System (INIS)

    Prise, Kevin M.

    2004-01-01

    The extended abstracts which are submitted here present a summary of the proceedings of the 6th International Workshop/12th LH Gray Workshop: Microbeam Probes of Cellular Radiation Response, held at St. Catherine's College, University of Oxford, UK on March, 29th-31st, 2003. In 1993 the 4th LH Gray Workshop entitled ''Microbeam Probes of Cellular Radiation Response'' was held at the Gray Cancer Institute in Northwood. This was organized by Prof BD Michael, Dr M. Folkard and Dr KM Prise and brought together 40 participants interested in developing and applying new microbeam technology to problems in radiation biology (1). The workshop was an undoubted success and has spawned a series of subsequent workshops every two years. In the past, these workshops have been highly successful in bringing together groups interested in developing and applying micro-irradiation techniques to the study of cell and tissue damage by ionizing radiations. Following the first microbeam workshop, there has been a rapid growth in the number of centres developing radiobiology microbeams, or planning to do so and there are currently 15-20 worldwide. Much of the recent research using microbeams has used them to study low-dose effects and ''non-targeted'' responses such bystander effects, genomic instability and adaptive responses. The goal of the 6th workshop was to build on our knowledge of the development of microbeam approaches and the application to radiation biology in the future with the meeting stretching over a 3 day period. Over 80 participants reviewed the current state of radiobiology microbeam research worldwide and reported on new technological developments both in the fields of physics and biology

  5. IMRT optimization: Variability of solutions and its radiobiological impact

    International Nuclear Information System (INIS)

    Mattia, Maurizio; Del Giudice, Paolo; Caccia, Barbara

    2004-01-01

    We aim at (1) defining and measuring a 'complexity' index for the optimization process of an intensity modulated radiation therapy treatment plan (IMRT TP), (2) devising an efficient approximate optimization strategy, and (3) evaluating the impact of the complexity of the optimization process on the radiobiological quality of the treatment. In this work, for a prostate therapy case, the IMRT TP optimization problem has been formulated in terms of dose-volume constraints. The cost function has been minimized in order to achieve the optimal solution, by means of an iterative procedure, which is repeated for many initial modulation profiles, and for each of them the final optimal solution is recorded. To explore the complexity of the space of such solutions we have chosen to minimize the cost function with an algorithm that is unable to avoid local minima. The size of the (sub)optimal solutions distribution is taken as an indicator of the complexity of the optimization problem. The impact of the estimated complexity on the probability of success of the therapy is evaluated using radiobiological indicators (Poissonian TCP model [S. Webb and A. E. Nahum, Phys. Med. Biol. 38(6), 653-666 (1993)] and NTCP relative seriality model [Kallman et al., Int. J. Radiat. Biol. 62(2), 249-262 (1992)]). We find in the examined prostate case a nontrivial distribution of local minima, which has symmetry properties allowing a good estimate of near-optimal solutions with a moderate computational load. We finally demonstrate that reducing the a priori uncertainty in the optimal solution results in a significant improvement of the probability of success of the TP, based on TCP and NTCP estimates

  6. Method for validating radiobiological samples using a linear accelerator.

    Science.gov (United States)

    Brengues, Muriel; Liu, David; Korn, Ronald; Zenhausern, Frederic

    2014-04-29

    There is an immediate need for rapid triage of the population in case of a large scale exposure to ionizing radiation. Knowing the dose absorbed by the body will allow clinicians to administer medical treatment for the best chance of recovery for the victim. In addition, today's radiotherapy treatment could benefit from additional information regarding the patient's sensitivity to radiation before starting the treatment. As of today, there is no system in place to respond to this demand. This paper will describe specific procedures to mimic the effects of human exposure to ionizing radiation creating the tools for optimization of administered radiation dosimetry for radiotherapy and/or to estimate the doses of radiation received accidentally during a radiation event that could pose a danger to the public. In order to obtain irradiated biological samples to study ionizing radiation absorbed by the body, we performed ex-vivo irradiation of human blood samples using the linear accelerator (LINAC). The LINAC was implemented and calibrated for irradiating human whole blood samples. To test the calibration, a 2 Gy test run was successfully performed on a tube filled with water with an accuracy of 3% in dose distribution. To validate our technique the blood samples were ex-vivo irradiated and the results were analyzed using a gene expression assay to follow the effect of the ionizing irradiation by characterizing dose responsive biomarkers from radiobiological assays. The response of 5 genes was monitored resulting in expression increase with the dose of radiation received. The blood samples treated with the LINAC can provide effective irradiated blood samples suitable for molecular profiling to validate radiobiological measurements via the gene-expression based biodosimetry tools.

  7. Saturation in dual radiation action

    International Nuclear Information System (INIS)

    Rossi, H.H.; Zaider, M.

    1988-01-01

    The theory of dual radiation action (TDRA) was developed with the aim of applying microdosimetry to radiobiology. It therefore can deal only with the first phases in a long chain of events that results in patent effects. It is, however, clear that the initial spatial and temporal pattern of energy deposition has a profound influence on the ultimate outcome. As often happens, the early formulation of the theory contained a number of simplifying assumptions. Although most of these were explicitly stated when the first version of the TDRA was published experimental data obtained when the limitations are important were cited as contrary evidence causing considerable confusion. A more advanced version eliminated some of the restrictions but there remain others, one of which relates to certain aspects of saturation which are addressed here

  8. Radiological and Environmental Research Division, Center for Human Radiobiology. Annual report, July 1980-June 1981

    International Nuclear Information System (INIS)

    1982-03-01

    Separate abstracts were prepared for the 22 papers of this annual report of the Center for Human Radiobiology. Abstracts were not written for 2 appendices which contain data on the exposure and radium-induced malignancies of 2259 persons whose radium content has been determined at least once

  9. Realization of radiobiological in vitro cell experiments at conventional X-ray tubes and unconventional radiation sources

    International Nuclear Information System (INIS)

    Beyreuther, Elke

    2010-01-01

    More than hundred years after the discovery of X-rays different kinds of ionizing radiation are ubiquitous in medicine, applied to clinical diagnostics and cancer treatment as well. Irrespective of their nature, the widespread application of radiation implies its precise dosimetric characterization and detailed knowledge of the radiobiological effects induced in cancerous and normal tissue. Starting with in vitro cell irradiation experiments, which define basic parameters for the subsequent tissue and animal studies, the whole multi-stage process is completed by clinical trials that translate the results of fundamental research into clinical application. In this context, the present dissertation focuses on the establishment of radiobiological in vitro cell experiments at unconventional, but clinical relevant radiation qualities. In the first part of the present work the energy dependent biological effectiveness of photons was studied examining low-energy X-rays (≤ 50 keV), as used for mammography, and high-energy photons (≥ 20 MeV) as proposed for future radiotherapy. Cell irradiation experiments have been performed at conventional X-ray tubes providing low-energy photons and 200 kV reference radiation as well. In parallel, unconventional quasi-monochromatic channeling X-rays and high-energy bremsstrahlung available at the radiation source ELBE of the Forschungszentrum Dresden-Rossendorf were considered for radiobiological experimentation. For their precise dosimetric characterization dosimeters based on the thermally stimulated emission of exoelectrons and on radiochromic films were evaluated, whereas just the latter was found to be suitable for the determination of absolute doses and spatial dose distributions at cell position. Standard ionization chambers were deployed for the online control of cell irradiation experiments. Radiobiological effects were analyzed in human mammary epithelial cells on different subcellular levels revealing an increasing amount

  10. Realization of radiobiological in vitro cell experiments at conventional X-ray tubes and unconventional radiation sources

    Energy Technology Data Exchange (ETDEWEB)

    Beyreuther, Elke

    2010-09-10

    More than hundred years after the discovery of X-rays different kinds of ionizing radiation are ubiquitous in medicine, applied to clinical diagnostics and cancer treatment as well. Irrespective of their nature, the widespread application of radiation implies its precise dosimetric characterization and detailed knowledge of the radiobiological effects induced in cancerous and normal tissue. Starting with in vitro cell irradiation experiments, which define basic parameters for the subsequent tissue and animal studies, the whole multi-stage process is completed by clinical trials that translate the results of fundamental research into clinical application. In this context, the present dissertation focuses on the establishment of radiobiological in vitro cell experiments at unconventional, but clinical relevant radiation qualities. In the first part of the present work the energy dependent biological effectiveness of photons was studied examining low-energy X-rays (≤ 50 keV), as used for mammography, and high-energy photons (≥ 20 MeV) as proposed for future radiotherapy. Cell irradiation experiments have been performed at conventional X-ray tubes providing low-energy photons and 200 kV reference radiation as well. In parallel, unconventional quasi-monochromatic channeling X-rays and high-energy bremsstrahlung available at the radiation source ELBE of the Forschungszentrum Dresden-Rossendorf were considered for radiobiological experimentation. For their precise dosimetric characterization dosimeters based on the thermally stimulated emission of exoelectrons and on radiochromic films were evaluated, whereas just the latter was found to be suitable for the determination of absolute doses and spatial dose distributions at cell position. Standard ionization chambers were deployed for the online control of cell irradiation experiments. Radiobiological effects were analyzed in human mammary epithelial cells on different subcellular levels revealing an increasing amount

  11. Activities of the radiobiological institute, the institute for experimental gerontology, and the primate center. Annual report, 1976

    International Nuclear Information System (INIS)

    1976-01-01

    Activities, presented by way of concise articles, cover the following subjects: radiation physics, radiobiology, experimental tumor therapy, tumor induction and tumor biology, immunology, transplantation and immunogenetics, hematology, gerontology, ethology, microbiology and quotobiology, techniques, and animals

  12. A community call for a dedicated radiobiological research facility to support particle beam cancer therapy

    DEFF Research Database (Denmark)

    Holzscheiter, Michael H.; Bassler, Niels; Dosanjh, Manjit

    2012-01-01

    Recently more than one hundred researchers followed an invitation to a brainstorming meeting on the topic of a future dedicated radio-biological and radio-physical research center. 100 more joint the meeting via webcast. After a day of presentations and discussions it was clear, that an urgent need...

  13. Use of the NASA Space Radiation Laboratory at Brookhaven National Laboratory to Conduct Charged Particle Radiobiology Studies Relevant to Ion Therapy.

    Science.gov (United States)

    Held, Kathryn D; Blakely, Eleanor A; Story, Michael D; Lowenstein, Derek I

    2016-06-01

    Although clinical studies with carbon ions have been conducted successfully in Japan and Europe, the limited radiobiological information about charged particles that are heavier than protons remains a significant impediment to exploiting the full potential of particle therapy. There is growing interest in the U.S. to build a cancer treatment facility that utilizes charged particles heavier than protons. Therefore, it is essential that additional radiobiological knowledge be obtained using state-of-the-art technologies and biological models and end points relevant to clinical outcome. Currently, most such ion radiotherapy-related research is being conducted outside the U.S. This article addresses the substantial contributions to that research that are possible at the NASA Space Radiation Laboratory (NSRL) at Brookhaven National Laboratory (BNL), which is the only facility in the U.S. at this time where heavy-ion radiobiology research with the ion species and energies of interest for therapy can be done. Here, we briefly discuss the relevant facilities at NSRL and how selected charged particle biology research gaps could be addressed using those facilities.

  14. Radiobiological effects of heavy ions and protons. [on cells of mammals, bacteria and viruses

    Science.gov (United States)

    Ryzhov, N. I.; Vorozhtsova, S. V.; Krasavin, Y. A.; Mashinskaya, T. Y.; Savchenko, N. Y.; Fedorov, B. S.; Khlaponina, V. F.; Shelegedin, V. N.; Gut, L.; Sabo, L.

    1974-01-01

    Radiobiological effects of heavy ions and protons are studied on cells of mammals, bacteria, viruses and DNA of bacteria. Results show that the dose effect dependence bears an exponential character; the reduction of RBE as LET of particle increases reflects the different character of microdistribution of absorbed energy in biological objects with different levels of biological organization.

  15. In vitro irradiation system for radiobiological experiments

    International Nuclear Information System (INIS)

    Tesei, Anna; Zoli, Wainer; D’Errico, Vincenzo; Romeo, Antonino; Parisi, Elisabetta; Polico, Rolando; Sarnelli, Anna; Arienti, Chiara; Menghi, Enrico; Medri, Laura; Gabucci, Elisa; Pignatta, Sara; Falconi, Mirella; Silvestrini, Rosella

    2013-01-01

    Although two-dimensional (2-D) monolayer cell cultures provide important information on basic tumor biology and radiobiology, they are not representative of the complexity of three-dimensional (3-D) solid tumors. In particular, new models reproducing clinical conditions as closely as possible are needed for radiobiological studies to provide information that can be translated from bench to bedside. We developed a novel system for the irradiation, under sterile conditions, of 3-D tumor spheroids, the in vitro model considered as a bridge between the complex architectural organization of in vivo tumors and the very simple one of in vitro monolayer cell cultures. The system exploits the same equipment as that used for patient treatments, without the need for dedicated and highly expensive instruments. To mimic the passage of radiation beams through human tissues before they reach the target tumor mass, 96-multiwell plates containing the multicellular tumor spheroids (MCTS) are inserted into a custom-built phantom made of plexiglass, the material most similar to water, the main component of human tissue. The system was used to irradiate CAEP- and A549-derived MCTS, pre-treated or not with 20 μM cisplatin, with a dose of 20 Gy delivered in one session. We also tested the same treatment schemes on monolayer CAEP and A549 cells. Our preliminary results indicated a significant increment in radiotoxicity 20 days after the end of irradiation in the CAEP spheroids pre-treated with cisplatin compared to those treated with cisplatin or irradiation alone. Conversely, the effect of the radio- chemotherapy combination in A549-derived MCTS was similar to that induced by cisplatin or irradiation alone. Finally, the 20 Gy dose did not affect cell survival in monolayer CAEP and A549 cells, whereas cisplatin or cisplatin plus radiation caused 100% cell death, regardless of the type of cell line used. We set up a system for the irradiation, under sterile conditions, of tumor cells

  16. Radiobiological modelling of dose-gradient effects in low dose rate, high dose rate and pulsed brachytherapy

    International Nuclear Information System (INIS)

    Armpilia, C; Dale, R G; Sandilos, P; Vlachos, L

    2006-01-01

    This paper presents a generalization of a previously published methodology which quantified the radiobiological consequences of dose-gradient effects in brachytherapy applications. The methodology uses the linear-quadratic (LQ) formulation to identify an equivalent biologically effective dose (BED eq ) which, if applied uniformly to a specified tissue volume, would produce the same net cell survival as that achieved by a given non-uniform brachytherapy application. Multiplying factors (MFs), which enable the equivalent BED for an enclosed volume to be estimated from the BED calculated at the dose reference surface, have been calculated and tabulated for both spherical and cylindrical geometries. The main types of brachytherapy (high dose rate (HDR), low dose rate (LDR) and pulsed (PB)) have been examined for a range of radiobiological parameters/dimensions. Equivalent BEDs are consistently higher than the BEDs calculated at the reference surface by an amount which depends on the treatment prescription (magnitude of the prescribed dose) at the reference point. MFs are closely related to the numerical BED values, irrespective of how the original BED was attained (e.g., via HDR, LDR or PB). Thus, an average MF can be used for a given prescribed BED as it will be largely independent of the assumed radiobiological parameters (radiosensitivity and α/β) and standardized look-up tables may be applicable to all types of brachytherapy treatment. This analysis opens the way to more systematic approaches for correlating physical and biological effects in several types of brachytherapy and for the improved quantitative assessment and ranking of clinical treatments which involve a brachytherapy component

  17. Paul Scherrer Institut annual report 1995. Annex II: PSI life sciences and institute for medical radiobiology newsletter 1995

    Energy Technology Data Exchange (ETDEWEB)

    Blaeuenstein, P; Gschwend, B [eds.

    1996-09-01

    The newsletter presents the 1995 progress report of PSI F2-Department and of the Institute for Medical Radiobiology in the fields of radiation medicine, radiopharmacy and radiation hygiene. figs., tabs., refs.

  18. Paul Scherrer Institut annual report 1995. Annex II: PSI life sciences and institute for medical radiobiology newsletter 1995

    International Nuclear Information System (INIS)

    Blaeuenstein, P.; Gschwend, B.

    1996-01-01

    The newsletter presents the 1995 progress report of PSI F2-Department and of the Institute for Medical Radiobiology in the fields of radiation medicine, radiopharmacy and radiation hygiene. figs., tabs., refs

  19. Method for validating radiobiological samples using a linear accelerator

    International Nuclear Information System (INIS)

    Brengues, Muriel; Liu, David; Korn, Ronald; Zenhausern, Frederic

    2014-01-01

    There is an immediate need for rapid triage of the population in case of a large scale exposure to ionizing radiation. Knowing the dose absorbed by the body will allow clinicians to administer medical treatment for the best chance of recovery for the victim. In addition, today's radiotherapy treatment could benefit from additional information regarding the patient's sensitivity to radiation before starting the treatment. As of today, there is no system in place to respond to this demand. This paper will describe specific procedures to mimic the effects of human exposure to ionizing radiation creating the tools for optimization of administered radiation dosimetry for radiotherapy and/or to estimate the doses of radiation received accidentally during a radiation event that could pose a danger to the public. In order to obtain irradiated biological samples to study ionizing radiation absorbed by the body, we performed ex-vivo irradiation of human blood samples using the linear accelerator (LINAC). The LINAC was implemented and calibrated for irradiating human whole blood samples. To test the calibration, a 2 Gy test run was successfully performed on a tube filled with water with an accuracy of 3% in dose distribution. To validate our technique the blood samples were ex-vivo irradiated and the results were analyzed using a gene expression assay to follow the effect of the ionizing irradiation by characterizing dose responsive biomarkers from radiobiological assays. The response of 5 genes was monitored resulting in expression increase with the dose of radiation received. The blood samples treated with the LINAC can provide effective irradiated blood samples suitable for molecular profiling to validate radiobiological measurements via the gene-expression based biodosimetry tools. (orig.)

  20. Radon as a remedy - radiobiological and medical aspects, risk

    International Nuclear Information System (INIS)

    Schwarz, E.R.; Nuernberger, E.; Martignoni, K.

    1995-01-01

    For years there have been controversial discussions about the benefit and risk of radon-balneo-therapy. This is particularly true where the inhalation of radon and its daughter products in curative galleries is concerned. Animal experiments and studies on uranium miners have clearly shown that the exposure with radon and its daughter products is connected with an additional risk for lung cancer. Findings on balneo-therapeutic mechanisms are, at best, incomplete and the topic of controversial discussions in radiobiology. This applies specifically to 'hormesis' or 'adaptive response', as indicated in this context. Given the numerous reports of therapeutic results, there appear to be curative effects from radon-balneotherapy for special indications. (orig.) [de

  1. GBD 2000 - Proceedings of the 4. annual meeting of 'Gesellschaft fuer Biologische Strahlenforschung'; GBS 2000 - Proceedings der 4. Jahrestagung der Gesellschaft fuer Biologische Strahlenforschung

    Energy Technology Data Exchange (ETDEWEB)

    Eckardt-Schupp, F.; Ahne, F.; Kistler, M. (eds.) [Gesellschaft fuer Strahlen- und Umweltforschung mbH Muenchen, Neuherberg (Germany). Inst. fuer Strahlenbiologie

    2000-07-01

    The headings of the meeting were as follows: Radiation chemistry and micro beam irradiation; DNA radiation damage and biological models; DNA repair; genetic radiation effects; radiation effects and stress effects on gene expression; cellular radiobiology; radiobiology of tumors and normal tissues; epidemiology.

  2. GBD 2000 - Proceedings of the 4. annual meeting of 'Gesellschaft fuer Biologische Strahlenforschung'

    International Nuclear Information System (INIS)

    Eckardt-Schupp, F.; Ahne, F.; Kistler, M.

    2000-01-01

    The headings of the meeting were as follows: Radiation chemistry and micro beam irradiation; DNA radiation damage and biological models; DNA repair; genetic radiation effects; radiation effects and stress effects on gene expression; cellular radiobiology; radiobiology of tumors and normal tissues; epidemiology

  3. Preliminary study on proteomic technique in radiobiological characteristics in nasopharyngeal carcinoma cell line

    International Nuclear Information System (INIS)

    Wang Hui; Yi Xuping; Hu Bingqiang; Zeng Liang; Liu Yisong; Liang Songping

    2007-01-01

    Objective: To examine the variation of protein expression in nasopharyngeal carcinoma cell lines with different biological characteristics and to identify the radiobiological associated proteins. Methods: Biological characteristics of 5-8F and 6-10B were compared by flow cytometry assay after irradiation. The total proteins of 5-8F and 6-10B were separated by immobilized pH gradient(IPG) IEF-SDS two-dimensional gel eleetrophoresis technique. The differentially expressed proteins were cut from the gel and digested into peptides for MALDI-TOF MS and the Q-TOF mass spectrometric analysis. Identification of protein was made through searching in protein sequence database. Protein expressions were examined by western blot and immunohistochemistry method. Results: Nine most differentially expressed proteins between 5-8F cell and 6-10B cell were identified, p73 and CK19 expression examined by western blot were conformal with that by proteomic method, p73 expression in 5-8F cell was higher than in 6-10B cell. CK19 expression in 6- 10B cell was higher than in 5-8F cell. Conclusion: Differentially expression of proteins exist in nasopharyngeal carcinoma cell lines with different biological characteristics. These proteins may be associated with cell radiobiological characteristic with the p73 as a potential biomarker. (authors)

  4. Design of a radiation facility for very small specimens used in radiobiology studies

    Science.gov (United States)

    Rodriguez, Manuel; Jeraj, Robert

    2008-06-01

    A design of a radiation facility for very small specimens used in radiobiology is presented. This micro-irradiator has been primarily designed to irradiate partial bodies in zebrafish embryos 3-4 mm in length. A miniature x-ray, 50 kV photon beam, is used as a radiation source. The source is inserted in a cylindrical brass collimator that has a pinhole of 1.0 mm in diameter along the central axis to produce a pencil photon beam. The collimator with the source is attached underneath a computer-controlled movable table which holds the specimens. Using a 45° tilted mirror, a digital camera, connected to the computer, takes pictures of the specimen and the pinhole collimator. From the image provided by the camera, the relative distance from the specimen to the pinhole axis is calculated and coordinates are sent to the movable table to properly position the samples in the beam path. Due to its monitoring system, characteristic of the radiation beam, accuracy and precision of specimen positioning, and automatic image-based specimen recognition, this radiation facility is a suitable tool to irradiate partial bodies in zebrafish embryos, cell cultures or any other small specimen used in radiobiology research.

  5. Dictionary of radiation protection, radiobiology and nuclear medicine. English-German-French-Russian

    International Nuclear Information System (INIS)

    Sube, R.

    1985-01-01

    This multilingual dictionary covers the subject fields of radiation protection, radiobiology, and nuclear medicine with about 12,000 terms in each language. All terms are supplemented by one or more abbreviations of 22 special branches to assure the use of the very relevant terms. Special branches listed are for instance decontamination, dosimetry, atomic legislation, radiation detectors, radiography (medical), radiotherapy, safeguards, shielding, tansportation and storage. The terminology used in the International Nuclear Information System (INIS) of the IAEA has been completely taken into account

  6. Radiobiological parameters of a human tumor parent line and four tumor clones of a human epidermoid carcinoma

    International Nuclear Information System (INIS)

    Weichselbaum, R.R.; Beckett, M.; Dahlberg, W.

    1987-01-01

    The authors examined the radiobiological parameters of a parent tumor line and four tumor clones of a human squamous cell carcinoma of the skin. The parent line and clones have a tumor morphology, aneuploid karyotype, and the ability to passage continuously in vitro. With the exception of clone F2A, all cell lines form tumors in nude mice. The parent line, SCC-12 has a D/sub o/ of 154 and an n 7.5 In four tumor clones, D/sub o/ ranges from 131 (clone V) to 266 (clone B2); n ranges from 22.8 in clone V to 2.1 in clone B2. PLDR following 1100 rad ranges from 1.7 in clone B2 to 13.1 in clone V. However, PLDR following equitoxic doses of radiation is similar in the parent and all sub-clones. Radiobiological heterogeneity may complicate predictive assays for clinical radiotherapy

  7. Radiobiological work using a negative pion beam at the Rutherford Laboratory 1971-76

    International Nuclear Information System (INIS)

    Ellis, R.E.; Lindop, P.J.; Coggle, J.E.; Fraser, G.

    1976-08-01

    The subject is discussed in two sections: physics experiments (including, inter alia, dose measurement, LET distribution, radiation products of spallation); radiobiological studies (including separate reports as follows: review of experimental programme; some in vivo effects of negative pions in mice; survival and recovery of Hela cells in vitro; negative pion dose-response curves for frozen Hela cells; response of vicia faba to irradiation with negative pions; pion experiments with chromosome aberrations). (U.K.)

  8. Influence of the radio-tracer used in diagnostic nuclear medicine upon the dose at the nucleus of cellular localisation

    International Nuclear Information System (INIS)

    Gardin, I.; Faraggi, M.; Stievenart, J.L; Le Guludec, D.; Bok, B.

    1997-01-01

    In the classical dosimetry one supposes a uniform distribution of the radio-pharmaceuticals at the source organ level as well as a homogeneous distribution of the absorbed dose. This hypotheses are not always verified in biology, and the influence of the tracer localisation on the dose delivered at the cellular nucleus has been studied. The average dose delivered by the electron emission of different radio-isotopes used in diagnosis has been calculated by taking into account the radioactivity localized upon the target cell (Dself), and upon the neighbouring cells (Dcross). Nuclear, cytoplasmic and membranous localizations of the tracer were simulated for different cellular sizes. In the particular case of 99m Tc and cells of nuclear radius about 4 μm and cellular radios about 8 μ, Dcross is independent of the intra-cellular localisation of the tracer. On the contrary, for a nuclear localisation Dself is 52 and 157 times more important than for the cytoplasmic and membranous localisation, respectively. The dose at the cellular nucleus due to electron emission of 99m Tc is under-estimated by a factor 2.6 by classical dosimetry when the radioactivity is nuclear. On the contrary, the classical model over-estimates by a factor 1.2 the dose at nucleus for cytoplasmic and membranous localizations. This study shows that the dose delivered at cellular nucleus by the electron emissions of 99m Tc depends on the localisation of the tracer. The modelling proposed allows a better evaluation of the radiobiological hazards related to the administration of radiopharmaceuticals in diagnostic nuclear medicine

  9. Osteopontin and splice variant expression level in human malignant glioma: Radiobiologic effects and prognosis after radiotherapy

    International Nuclear Information System (INIS)

    Güttler, Antje; Giebler, Maria; Cuno, Peter; Wichmann, Henri; Keßler, Jacqueline; Ostheimer, Christian; Söling, Ariane; Strauss, Christian; Illert, Jörg; Kappler, Matthias; Vordermark, Dirk; Bache, Matthias

    2013-01-01

    Background and purpose: We investigated the role of the hypoxia-associated secreted glycoprotein osteopontin (OPN) in the response of malignant glioma to radiotherapy by characterizing OPN and its splice variants in vitro and in patient material. Material and methods: The effect of siRNA knockdown of OPN splice variants on cellular and radiobiologic behavior was analyzed in U251MG cells using OpnS siRNA (inhibition of all OPN splice variants) and OpnAC siRNA (knockdown only of OPNa and OPNc). OPN and splice variant mRNA levels were quantified in archival material of 41 glioblastoma tumor samples. Plasma OPN was prospectively measured in 33 malignant glioma patients. Results: Inhibition of OPNa and OPNc (OpnAC) reduced clonogenic survival in U251MG cells but did not affect proliferation, migration or apoptosis. Knockdown of all OPN splice variants (OpnS) resulted in an even stronger inhibition of clonogenic survival, while cell proliferation and migration were reduced and rate of apoptosis was increased. Additional irradiation had additive effects with both siRNAs. Plasma OPN increased continuously in malignant glioma patients and was associated with poor survival. Conclusions: OPNb is partially able to compensate the effects of OPNa and OPNc knockdown in U251MG cells. High OPN plasma levels at the end of radiotherapy are associated with poor survival

  10. Paul Scherrer Institut annual report 1996. Annex II: PSI life sciences and Institute for Medical Radiobiology Newsletter 1996

    International Nuclear Information System (INIS)

    Kuehne, G.; Gschwend, B.

    1997-01-01

    This annex to the PSI Annual Report 1996 reports on the progress achieved by the PSI Department II during 1996 in the fields of radiation medicine, radiopharmacy, radiation hygiene, positron emission tomography and medical radiobiology. figs., tab., refs

  11. Dictionary of radiation protection, radiobiology and nuclear medicine

    Energy Technology Data Exchange (ETDEWEB)

    Sube, R [comp.

    1986-01-01

    Radiation protection, including aspects of radiobiology, nuclear medicine, and nuclear legislation, has an important role within nuclear research and the use of radioactive materials. Radiation protection comprises all measures and efforts to prevent the unwanted distribution and negative influence of ionizing radiation, especially where the human organism and the living environment are involved. The increasing role of radiation protection is reflected by the foundation of institutes in all industrial countries to control such radiant energy and prevent radiation damage. Nowadays ionizing radiation is employed on a large scale for basic investigations in biochemistry, molecular biology and genetics, in soil tests, fertilization problems and pest control in agriculture, as well as for medicinal diagnoses and therapy. This dictionary is a thematic enlargement of the four-language 'Dictionary of Nuclear Engineering', compiled by the same author. It comprises about 12,000 terms in each language.

  12. Linear versus non-linear: a perspective from health physics and radiobiology

    International Nuclear Information System (INIS)

    Gentner, N.E.; Osborne, R.V.

    1998-01-01

    There is a vigorous debate about whether or not there may be a 'threshold' for radiation-induced adverse health effects. A linear-no threshold (LNT) model allows radiation protection practitioners to manage putative risk consistently, because different types of exposure, exposures at different times, and exposures to different organs may be summed. If we are to argue to regulators and the public that low doses are less dangerous than we presently assume, it is incumbent on us to prove this. The question is, therefore, whether any consonant body of evidence exists that the risk of low doses has been over-estimated. From the perspectives of both health physics and radiobiology, we conclude that the evidence for linearity at high doses (and arguably of fairly small total doses if delivered at high dose rate) is strong. For low doses (or in fact, even for fairly high doses) delivered at low dose rate, the evidence is much less compelling. Since statistical limitations at low doses are almost always going to prevent a definitive answer, one way or the other, from human data, we need a way out of this epistemological dilemma of 'LNT or not LNT, that is the question'. To our minds, the path forward is to exploit (1) radiobiological studies which address directly the question of what the dose and dose rate effectiveness factor is in actual human bodies exposed to low-level radiation, in concert with (2) epidemiological studies of human populations exposed to fairly high doses (to obtain statistical power) but where exposure was protracted over some years. (author)

  13. Probing Cellular Dynamics with Mesoscopic Simulations

    DEFF Research Database (Denmark)

    Shillcock, Julian C.

    2010-01-01

    Cellular processes span a huge range of length and time scales from the molecular to the near-macroscopic. Understanding how effects on one scale influence, and are themselves influenced by, those on lower and higher scales is a critical issue for the construction of models in Systems Biology....... Advances in computing hardware and software now allow explicit simulation of some aspects of cellular dynamics close to the molecular scale. Vesicle fusion is one example of such a process. Experiments, however, typically probe cellular behavior from the molecular scale up to microns. Standard particle...... soon be coupled to Mass Action models allowing the parameters in such models to be continuously tuned according to the finer resolution simulation. This will help realize the goal of a computational cellular simulation that is able to capture the dynamics of membrane-associated processes...

  14. Biochemical and Radiobiological Factors in the Early Detection of Radiation Injury in Mammals

    Energy Technology Data Exchange (ETDEWEB)

    Cole, L. J. [Life Sciences Division, Stanford Research Institute, Menlo Park, CA (United States)

    1971-03-15

    In considering the body of radiobiological knowledge upon which the present possibilities for the development of an objective quantitative laboratory procedure for early detection of radiation injury depend, it is evident that there are at least three general categories of radiation effects which are relevant to this objective: (1) Products of the enzymatic-chemical breakdown of macromolecules, and lysis of killed or dying cells from radiosensitive tissues, for example deoxypolynucleotides from lymphoid tissues and bone marrow; (2) Radiation-induced inhibition of synthesis of deoxyribonucleic acid (DNA) and/or other macromolecules, eliciting alterations in tissue and blood concentrations and pool size of metabolic intermediates in the synthesis, for example, deoxycytidine; (3) Radiation-induced alterations, suppression, or cessation of specialized cell function; of particular interest here is the immunological functions of lymphocytes, including those in the circulating blood. For rodents, the exquisite radiosensitivity of bone-marrow-stem cells as well as of lymphocytes has been precisely measured by modern cellular radiobiological techniques: the colony-forming technique of Till and McCulloch, yielding a D{sub 0} for bone-marrow cells of about 80 R; and the graft-versus-host reactivity of transplanted lymphocytes yielding a similar D{sub 0} value. In our own hands, a modified colony-formation technique for dog bone-marrow cells irradiated in.vitro and in vivo give D{sub 0} values of {approx}100 R. Thus, on the basis of radiation sensitivity and the time-relationships for interphase cell death for lymphocytes, it appears that this cell class is probably the best ''candidate'' source for an early radiation-injury detection system. However,- the important report by Zicha and Buric indicates that extrapolation of biochemical data on radiation dosimetry from rodents to man is not necessarily feasible, at least in the. case of the urinary excretion of deoxycytidine

  15. Mechanism of action of sodium hypochlorite

    Directory of Open Access Journals (Sweden)

    Estrela Carlos

    2002-01-01

    Full Text Available The choice of an irrigating solution for use in infected root canals requires previous knowledge of the microorganisms responsible for the infectious process as well as the properties of different irrigating solutions. Complex internal anatomy, host defenses and microorganism virulence are important factors in the treatment of teeth with asymptomatic apical periodontitis. Irrigating solutions must have expressive antimicrobial action and tissue dissolution capacity. Sodium hypochlorite is the most used irrigating solution in endodontics, because its mechanism of action causes biosynthetic alterations in cellular metabolism and phospholipid destruction, formation of chloramines that interfere in cellular metabolism, oxidative action with irreversible enzymatic inactivation in bacteria, and lipid and fatty acid degradation. The aim of this work is to discuss the mechanism of action of sodium hypochlorite based on its antimicrobial and physico-chemical properties.

  16. European Society for Radiation Biology 21. annual meeting

    International Nuclear Information System (INIS)

    1988-01-01

    The volume contains about 100 abstracts of lectures presented to the conference covering a large variety of topics like: Radiobiology as a base for radiotherapy, radiation carcinogenesis and cellular effects, late and secondary effects of radiotherapy, radioprotection and radiosensitization, heavy ions in radiobiology and space research, microdosimetry and biological dosimetry, radiation effects on the mature and the developing central nervous system, DNA damage and repair and cellular mutations, the imact of radiation on the environment, free radicals in radiation biology

  17. MO-D-BRD-03: Radiobiology and Commissioning of Electronic Brachytherapy for IORT

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, J. [Oregon Health & Science Univ (United States)

    2015-06-15

    Electronic brachytherapy (eBT) has seen an insurgence of manufacturers entering the US market for use in radiation therapy. In addition to the established interstitial, intraluminary, and intracavitary applications of eBT, many centers are now using eBT to treat skin lesions. It is important for medical physicists working with electronic brachytherapy sources to understand the basic physics principles of the sources themselves as well as the variety of applications for which they are being used. The calibration of the sources is different from vendor to vendor and the traceability of calibrations has evolved as new sources came to market. In 2014, a new air-kerma based standard was introduced by the National Institute of Standards and Technology (NIST) to measure the output of an eBT source. Eventually commercial treatment planning systems should accommodate this new standard and provide NIST traceability to the end user. The calibration and commissioning of an eBT system is unique to its application and typically entails a list of procedural recommendations by the manufacturer. Commissioning measurements are performed using a variety of methods, some of which are modifications of existing AAPM Task Group protocols. A medical physicist should be familiar with the different AAPM Task Group recommendations for applicability to eBT and how to properly adapt them to their needs. In addition to the physical characteristics of an eBT source, the photon energy is substantially lower than from HDR Ir-192 sources. Consequently, tissue-specific dosimetry and radiobiological considerations are necessary when comparing these brachytherapy modalities and when making clinical decisions as a radiation therapy team. In this session, the physical characteristics and calibration methodologies of eBt sources will be presented as well as radiobiology considerations and other important clinical considerations. Learning Objectives: To understand the basic principles of electronic

  18. Simple preparation of thin CR-39 detectors for alpha-particle radiobiological experiments

    International Nuclear Information System (INIS)

    Chan, K.F.; Lau, B.M.F.; Nikezic, D.; Tse, A.K.W.; Fong, W.F.; Yu, K.N.

    2007-01-01

    Alpha-particle radiobiological experiments involve irradiating cells with alpha particles and require accurate positions where the alpha particles hit the cells. In the present work, we prepared thin CR-39 detectors from commercially available CR-39 SSNTDs with a thickness of 100 μm by etching them in 1 N NaOH/ethanol at 40 deg. C to below 20 μm. The desired final thickness was achieved within ∼8 h. Such etching conditions can provide relatively small roughness of the detector as revealed by atomic force microscope, and thus provide transparent detectors for radiobiological experiments. UV radiation was employed to shorten track formation time on these thin CR-39 detectors. After exposure to UV light (UVA + B radiation) for 2-3 h with doses from 259 to 389 W/cm 2 , 5 MeV alpha-particle tracks can be seen to develop on these CR-39 detectors clearly under the optical microscope within 2 h in 14 N KOH at 37 deg. C. As an example for practical use, custom-made petri dishes, with a hole drilled at the bottom and covered with a thin CR-39 detector, were used for culturing HeLa cells. The feasibility of using these thin CR-39 detectors is demonstrated by taking photographs of the cells and alpha-particle tracks together under the optical microscope, which can allow the hit positions on the cells by the alpha particles to be determined accurately

  19. Radiobiological Determination of Dose Escalation and Normal Tissue Toxicity in Definitive Chemoradiation Therapy for Esophageal Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Warren, Samantha, E-mail: Samantha.warren@oncology.ox.ac.uk [Department of Oncology, Gray Institute of Radiation Oncology and Biology, University of Oxford, Oxford (United Kingdom); Partridge, Mike [Department of Oncology, Gray Institute of Radiation Oncology and Biology, University of Oxford, Oxford (United Kingdom); Carrington, Rhys [Velindre Cancer Centre, Velindre Hospital, Cardiff (United Kingdom); Hurt, Chris [Wales Cancer Trials Unit, School of Medicine, Heath Park, Cardiff (United Kingdom); Crosby, Thomas [Velindre Cancer Centre, Velindre Hospital, Cardiff (United Kingdom); Hawkins, Maria A. [Department of Oncology, Gray Institute of Radiation Oncology and Biology, University of Oxford, Oxford (United Kingdom)

    2014-10-01

    Purpose: This study investigated the trade-off in tumor coverage and organ-at-risk sparing when applying dose escalation for concurrent chemoradiation therapy (CRT) of mid-esophageal cancer, using radiobiological modeling to estimate local control and normal tissue toxicity. Methods and Materials: Twenty-one patients with mid-esophageal cancer were selected from the SCOPE1 database (International Standard Randomised Controlled Trials number 47718479), with a mean planning target volume (PTV) of 327 cm{sup 3}. A boost volume, PTV2 (GTV + 0.5 cm margin), was created. Radiobiological modeling of tumor control probability (TCP) estimated the dose required for a clinically significant (+20%) increase in local control as 62.5 Gy/25 fractions. A RapidArc (RA) plan with a simultaneously integrated boost (SIB) to PTV2 (RA{sub 62.5}) was compared to a standard dose plan of 50 Gy/25 fractions (RA{sub 50}). Dose-volume metrics and estimates of normal tissue complication probability (NTCP) for heart and lungs were compared. Results: Clinically acceptable dose escalation was feasible for 16 of 21 patients, with significant gains (>18%) in tumor control from 38.2% (RA{sub 50}) to 56.3% (RA{sub 62.5}), and only a small increase in predicted toxicity: median heart NTCP 4.4% (RA{sub 50}) versus 5.6% (RA{sub 62.5}) P<.001 and median lung NTCP 6.5% (RA{sub 50}) versus 7.5% (RA{sub 62.5}) P<.001. Conclusions: Dose escalation to the GTV to improve local control is possible when overlap between PTV and organ-at-risk (<8% heart volume and <2.5% lung volume overlap for this study) generates only negligible increase in lung or heart toxicity. These predictions from radiobiological modeling should be tested in future clinical trials.

  20. Radiological and Environmental Research Division, Center for Human Radiobiology. Annual report, July 1980-June 1981. [Lead abstract

    Energy Technology Data Exchange (ETDEWEB)

    1982-03-01

    Separate abstracts were prepared for the 22 papers of this annual report of the Center for Human Radiobiology. Abstracts were not written for 2 appendices which contain data on the exposure and radium-induced malignancies of 2259 persons whose radium content has been determined at least once. (KRM)

  1. Radiobiological experiments with heavy ions

    International Nuclear Information System (INIS)

    Kraft, G.

    1988-11-01

    In experiments, performed at the Unilac, Bevalac, and Ganil a large body of radiobiological data, cross sections for cell inactivation and mutation, induction of both, chromosome aberrations, and strand breaks of DNA have been measured for different atomic numbers, from helium (Z=2) to uranium (Z=92), and at an LET range from 10 to 16000 keV/μm. These data exhibit a common feature: At LET values below 100 keV/μm all data points of one specific effect form one single curve as a function of LET, independent from the atomic number of the ion. In this LET range, the biological effects are independ from the particle energy or track structure and depend only on the energy transfer. Therefore, LET is a good parameter in this regime. For LET values greater than 100 keV/μm, the curves for the different ions separate from the common curve in order of increasing atomic numbers. In this regime LET is no longer a good parameter and the physical parameters of the formation of particle tracks are important. The similarity of the σ-LET curves for different endpoints shows that the 'hook-structure' is produced by physical and chemical effects which occur before the biologically relevant lesions are formed. For this part of the reaction chain only a very limited amount of data are available. (orig./MG)

  2. Dictionary of radiation protection, radiobiology and nuclear medicine

    International Nuclear Information System (INIS)

    Sube, R.

    1986-01-01

    Radiation protection, including aspects of radiobiology, nuclear medicine, and nuclear legislation, has an important role within nuclear research and the use of radioactive materials. Radiation protection comprises all measures and efforts to prevent the unwanted distribution and negative influence of ionizing radiation, especially where the human organism and the living environment are involved. The increasing role of radiation protection is reflected by the foundation of institutes in all industrial countries to control such radiant energy and prevent radiation damage. Nowadays ionizing radiation is employed on a large scale for basic investigations in biochemistry, molecular biology and genetics, in soil tests, fertilization problems and pest control in agriculture, as well as for medicinal diagnoses and therapy. This dictionary is a thematic enlargement of the four-language 'Dictionary of Nuclear Engineering', compiled by the same author. It comprises about 12,000 terms in each language. (orig.)

  3. Characteristics of Middle School Students Learning Actions in Outdoor Mathematical Activities with the Cellular Phone

    Science.gov (United States)

    Daher, Wajeeh; Baya'a, Nimer

    2012-01-01

    Learning in the cellular phone environment enables utilizing the multiple functions of the cellular phone, such as mobility, availability, interactivity, verbal and voice communication, taking pictures or recording audio and video, measuring time and transferring information. These functions together with mathematics-designated cellular phone…

  4. Development of a compact laser-produced plasma soft X-ray source for radiobiology experiments

    Czech Academy of Sciences Publication Activity Database

    Adjei, D.; Ayele, M. G.; Wachulak, P.; Bartnik, A.; Wegrzynski, L.; Fiedorowicz, H.; Vyšín, Luděk; Wiechec, A.; Lekki, J.; Kwiatek, W. M.; Pina, L.; Davídková, Marie; Juha, Libor

    2015-01-01

    Roč. 364, Dec (2015), s. 27-32 ISSN 0168-583X R&D Projects: GA ČR(CZ) GBP108/12/G108; GA ČR GA13-28721S EU Projects: European Commission(XE) 284464 - LASERLAB-EUROPE Institutional support: RVO:68378271 ; RVO:61389005 Keywords : laser-produced plasma * soft X-rays * radiobiology * gas puff target * water window Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.389, year: 2015

  5. SU-G-TeP3-11: Radiobiological-Cum-Dosimetric Quality Assurance of Complex Radiotherapy Plans

    Energy Technology Data Exchange (ETDEWEB)

    Paudel, N; Narayanasamy, G; Zhang, X; Penagaricano, J; Morrill, S [University of Arkansas for Medical Sciences, Little Rock, AR (United States); Mavroidis, P [University North Carolina, Chapel Hill, NC (United States); Pyakuryal, A [National Cancer Institute, Rockville, MD (United States); Han, E [UT MD Anderson Cancer Center, Houston, TX (United States); Liang, X [University of Florida Health Proton Therapy Institute, Jacksonville, FL (United States); Kim, D [Kyung Hee University Hospital, Seol (Korea, Republic of)

    2016-06-15

    Purpose: Dosimetric gamma-analysis used for QA of complex radiotherapy plans tests the dosimetric equivalence of a delivered plan with the treatment planning system (TPS) optimized plan. It does not examine whether a dosimetric difference results in any radiobiological difference. This study introduces a method to test the radiobiological and dosimetric equivalence between a delivered and the TPS optimized plan. Methods: Six head and neck and seven lung cancer VMAT or IMRT plans optimized for patient treatment were calculated and delivered to an ArcCheck phantom. ArcCheck measured dose distributions were compared with the TPS calculated dose distributions using a 2-D gamma-analysis. Dose volume histograms (DVHs) for various patient structures were obtained by using measured data in 3DVH software and compared against the TPS calculated DVHs using 3-D gamma analysis. DVH data were used in the Poisson model to calculate tumor control probability (TCP) for the treatment targets and in the sigmoid dose response model to calculate normal tissue complication probability (NTCP) for the normal structures. Results: Two-D and three-D gamma passing rates among six H&N patient plans differed by 0 to 2.7% and among seven lung plans by 0.1 to 4.5%. Average ± SD TCPs based on measurement and TPS were 0.665±0.018 and 0.674±0.044 for H&N, and 0.791±0.027 and 0.733±0.031 for lung plans, respectively. Differences in NTCPs were usually negligible. The differences in dosimetric results, TCPs and NTCPs were insignificant. Conclusion: The 2-D and 3-D gamma-analysis based agreement between measured and planned dose distributions may indicate their dosimetric equivalence. Small and insignificant differences in TCPs and NTCPs based on measured and planned dose distributions indicate the radiobiological equivalence between the measured and optimized plans. However, patient plans showing larger differences between 2-D and 3-D gamma-analysis can help us make a more definite conclusion

  6. Radiobiological research for improving cancer therapy in India: rationale, problems and prospects

    International Nuclear Information System (INIS)

    Kalia, Vijay K.; Shobha, A.G.; KaIia, Anita; Saxena, Amit

    2012-01-01

    Cancer is emerging as a very important health hazard in India. According to recent studies by the Indian Council of Medical Research, about 2.25 million patients are presently suffering from different types of cancer in India. Approximately one million new cases are diagnosed, and nearly 0.3 million deaths occur every year on account of this disease. About 2/3rd of the cancers are at an advanced stage at the time of diagnosis. However, the allocation of funds for healthcare in India to support the research efforts for developing more potent radio-chemotherapy protocols for cancer treatment is too little. Studies by the W.H.O. have estimated that less developed countries including India use less than 5% of world resources destined for cancer control. It follows from the above discussions that it is imperative to further encourage and diversify the radiobiological research in India. This can be achieved by creating radiobiological research facilities, mainly in all the cancer centers and post graduate medical institutions, and further expanding the upcoming laboratories in the universities such as Bikaner. Collaborative research programs between laboratories at different centers could facilitate systematic evaluation of various pharmacological agents and neutraceuticals for potential application for treatment of different cancers. Our studies on combination of radiation with temozolomide and certain adjuvants with selective effects on brain tumour cells will be very briefly discussed in this presentation. Finally the possible administrative set up and multi dimensional collaborations for cost effective utilization of existing resources to further augment radiation biology research will also be discussed

  7. Radiobiological research on carnation chimerae Dianthus Caryophyllus L

    International Nuclear Information System (INIS)

    Pereau-Leroy, Pierre.

    1975-01-01

    A radiobiological study of periclinal carnation chimerae is carried out by subjecting whole plants and cuttings at different physiological stages to cobalt 60 gamma radiation under different dose and dose rate conditions. The effects of these treatments are observed during cultivation of the treated plants and by microscopic examination of irradiated meristem sections. The destruction of meristem cells in proportions varying with the irradiation conditions leads to structural changes in the chimerae; the more frequent change is the formation of genetically homogeneous stalks from different genotypes existing in the irradiated plant. Treatment by ionizing radiations is thus a practical means of detecting periclinical chimerae which, as in the case of carnations, are very common in plants grown by vegetative propagation. However since more than two independent meristem cell groups are usually present it is not possible by this method alone to define the distribution of the differentent genotypes in these groups; additional genetic studies or cell labelling such as chlorophyll or genoma mutations are then necessary [fr

  8. The Influence of nonuniform activity distribution on cellular dosimetry

    International Nuclear Information System (INIS)

    Naling, Song; Yuan, Tian; Liangan, Zhang; Guangfu, Dai

    2008-01-01

    S value is an important parameter in determination of absorbed dose in nuclear medicine and radiobiology. The distribution of radioactivity shows significant influence on the S value especially in microdosimetry. In present work, a semi Monte Carlo Model is developed to calculate the microdosimetric cellular S value for different micro-distributions of radioactivity, i.e. uniform, linear increase, linear decrease, exponential increase, exponential decrease and centroid distribution. Emission of alpha particles is simulated by Monte Carlo model and the energy imparted to the target volume is calculated by the analytical Continuous Slowing Down Approximation (CSDA) model and the spline interpolation of range-energy relationship. We calculate tables of S values for 213 Po and 210 Po with various dimensions and most important with various possible micro-distributions of radioactivity, such as linear increase, linear decrease, exponential increase and exponential decrease. Then we compare the S values from cell to cell of uniform distribution with the Hamacher's results to test the feasibility of our model. S values of some nonuniform micro-distributions are compared to the corresponding data of the uniform distribution. The possible sources of these differences are theoretical analyzed. (author)

  9. Interface between technical physics and technological irradiation with reference to applications in vegetal and animal radiobiology

    International Nuclear Information System (INIS)

    Peteu, G.; Opris, M.

    1994-01-01

    The main goals of vegetal and animal radiobiology in a specific correlation with technical physics are the stimulation of germination and induced mutations; vegetal and animal food conservation, sterilization techniques, and modifications in the radiosensitivity of biological systems. The existing correlation between the effects of exposed and absorbed doses, and the behaviour of the 'microflora' (microbes, fungi), are discussed. (Author)

  10. Co-ordinate action of bacterial adhesins and human carcinoembryonic antigen receptors in enhanced cellular invasion by capsulate serum resistant Neisseria meningitidis.

    Science.gov (United States)

    Rowe, Helen A; Griffiths, Natalie J; Hill, Darryl J; Virji, Mumtaz

    2007-01-01

    Neisseria meningitidis (Nm) is a human specific opportunistic pathogen that occasionally penetrates mucosal barriers via the action of adhesins and invasins and evades host immune mechanisms during further dissemination via capsule expression. From in vitro studies, the primary adhesion of capsulate bacteria is believed to be mediated by polymeric pili, followed by invasion via outer membrane adhesins such as Opa proteins. As the latter requires the surface capsule to be down-modulated, invading bacteria would be serum sensitive and thus avirulent. However, there is recent evidence that capsulate bacteria may interact via Opa proteins when host cells express high levels of carcinoembryonic antigen-related cell adhesion molecules (CEACAMs), their target receptors. Such a situation may arise following increased circulation of inflammatory cytokines that upregulate certain adhesion molecules on host cells. In this study, using a tetracycline controlled expression system, we have developed cell lines with inducible CEACAM expression to mimic post-inflammation state of target tissues and analysed the interplay between the three surface components capsule, pili and Opa proteins in cellular interactions. With two distinct cell lines, not only the level but also the rate of adhesion of capsulate Opa-expressing Nm increased concurrently with CEACAM density. Moreover, when threshold levels of receptor were reached, cellular invasion ensued in an Opa-dependent manner. In studies with cell lines intrinsically expressing pilus receptors, notable synergism in cellular interactions between pili and Opa of several meningococcal strains was observed and was independent of capsule type. A number of internalized bacteria were shown to express capsule and when directly isolated from host cells, these bacteria were as serum resistant as the inoculated phenotype. Furthermore, we observed that agents that block Opa-CEACAM binding substantially reduced cellular invasion, while maintaining

  11. Direct evaluation of radiobiological parameters from clinical data in the case of ion beam therapy: an alternative approach to the relative biological effectiveness

    International Nuclear Information System (INIS)

    Cometto, A; Russo, G; Giordanengo, S; Marchetto, F; Cirio, R; Attili, A; Bourhaleb, F; Milian, F M

    2014-01-01

    The relative biological effectiveness (RBE) concept is commonly used in treatment planning for ion beam therapy. Whether models based on in vitro/in vivo RBE data can be used to predict human response to treatments is an open issue. In this work an alternative method, based on an effective radiobiological parameterization directly derived from clinical data, is presented. The method has been applied to the analysis of prostate cancer trials with protons and carbon ions. Prostate cancer trials with proton and carbon ion beams reporting 5 year-local control (LC5) and grade 2 (G2) or higher genitourinary toxicity rates (TOX) were selected from literature to test the method. Treatment simulations were performed on a representative subset of patients to produce dose and linear energy transfer distribution, which were used as explicative physical variables for the radiobiological modelling. Two models were taken into consideration: the microdosimetric kinetic model (MKM) and a linear model (LM). The radiobiological parameters of the LM and MKM were obtained by coupling them with the tumor control probability and normal tissue complication probability models to fit the LC5 and TOX data through likelihood maximization. The model ranking was based on the Akaike information criterion. Results showed large confidence intervals due to the limited variety of available treatment schedules. RBE values, such as RBE = 1.1 for protons in the treated volume, were derived as a by-product of the method, showing a consistency with current approaches. Carbon ion RBE values were also derived, showing lower values than those assumed for the original treatment planning in the target region, whereas higher values were found in the bladder. Most importantly, this work shows the possibility to infer the radiobiological parametrization for proton and carbon ion treatment directly from clinical data. (paper)

  12. Preliminary results in the application of radiobiological models in the evaluation of radiotherapy plans

    International Nuclear Information System (INIS)

    Calderon, Carlos; Napoles, Mysleidis; Asencion, Yudy; Yanes, Yahima; Alfonso, Rodolfo; Gonzalez, Joaquin

    2009-01-01

    Notwithstanding the limitations of radiobiological models in the clinical application, its use is becoming more widespread in order to quantitatively assess the bioequivalence of different regimens of irradiation, the effective comparison between different treatment plans by estimating the probability tumor control (TCP) or the probability of normal tissue complication (NTCP), or solve problems, such as the rescheduling of treatments in case of failure. The response to irradiation in the tissues at risk (OARS) depends on factors such as volume irradiated or its organizational structure and behavior can vary for a given dose distribution. Another important aspect is the sensitivity of these models to the variation of parameters (α, α / β, proliferation, clonogenic density, etc.) Measuring the difference between-subjects. Commercial planning systems do not always possible to estimate the biological response of the OARS and CTV. This study presents an assessment of the results of two applications (free ware) and Albireo Target BIOPLAN Cygnus X1 that calculate statistical parameters of the DVH: equivalent uniform dose (EUD), equivalent biological dose (BED), medium dose and other to estimate TCP (Poisson model) and NTCP (Lyman-Kutcker models-Burman and relative seriality) for the calculation of the objective functions: the probability of uncomplicated control (UTCP) based on generalized EUD (f). We studied the response of both systems to the variation of relevant radiobiological parameters and the shape of the DVH. (Author)

  13. Preliminary results in the application of radiobiological models in the evaluation of radiotherapy plans

    International Nuclear Information System (INIS)

    Calderon, Carlos; Napoles, Mysleidis; Asencion, Yudy; Yanes, Yahima; Alfonso, Rodolfo; Gonzalez Joaquin

    2009-01-01

    Notwithstanding the limitations of radiobiological models in the clinical application, its use is becoming more widespread in order to quantitatively assess the bioequivalence of different regimens of irradiation, the effective comparison between different treatment plans by estimating the probability tumor control (TCP) or the probability of normal tissue complication (NTCP), or solve problems, such as the rescheduling of treatments in case of failure. The response to irradiation in the tissues at risk (OARS) depends on factors such as volume irradiated or its organizational structure and behavior can vary for a given dose distribution. Another important aspect is the sensitivity of these models to the variation of parameters (a, a / β, proliferation, clonogenic density, etc.) Measuring the difference between-subjects. Commercial planning systems do not always possible to estimate the biological response of the OARS and CTV. This study presents an assessment of the results of two applications (free ware) and Albireo Target BIOPLAN Cygnus X1 that calculate statistical parameters of the DVH: equivalent uniform dose (EUD), equivalent biological dose (BED), medium dose and other to estimate TCP (Poisson model) and NTCP (Lyman-models-Kutcker Burman and relative seriality) for the calculation of the objective functions: the probability of uncomplicated control (UTCP) based on generalized EUD (f). We studied the response of both systems to the variation of relevant radiobiological parameters and the shape of the DVH. (author)

  14. Radiobiological response to ultra-short pulsed megavoltage electron beams of ultra-high pulse dose rate.

    Science.gov (United States)

    Beyreuther, Elke; Karsch, Leonhard; Laschinsky, Lydia; Leßmann, Elisabeth; Naumburger, Doreen; Oppelt, Melanie; Richter, Christian; Schürer, Michael; Woithe, Julia; Pawelke, Jörg

    2015-08-01

    In line with the long-term aim of establishing the laser-based particle acceleration for future medical application, the radiobiological consequences of the typical ultra-short pulses and ultra-high pulse dose rate can be investigated with electron delivery. The radiation source ELBE (Electron Linac for beams with high Brilliance and low Emittance) was used to mimic the quasi-continuous electron beam of a clinical linear accelerator (LINAC) for comparison with electron pulses at the ultra-high pulse dose rate of 10(10) Gy min(-1) either at the low frequency of a laser accelerator or at 13 MHz avoiding effects of prolonged dose delivery. The impact of pulse structure was analyzed by clonogenic survival assay and by the number of residual DNA double-strand breaks remaining 24 h after irradiation of two human squamous cell carcinoma lines of differing radiosensitivity. The radiation response of both cell lines was found to be independent from electron pulse structure for the two endpoints under investigation. The results reveal, that ultra-high pulse dose rates of 10(10) Gy min(-1) and the low repetition rate of laser accelerated electrons have no statistically significant influence (within the 95% confidence intervals) on the radiobiological effectiveness of megavoltage electrons.

  15. Radiobiological effect of different irradiation fractionated regimens in human brain glioma

    International Nuclear Information System (INIS)

    Gai Xue; Yang Weizhi; Gao Li; Jiang Heng; Wang Mianrong; Shi Huizhen

    2010-01-01

    Objective: To evaluate the radiobiological effect of different irradiation fractionated regimens in human glioma cells (BT 325 cell line). Methods: The xenografts in Balb/c-nude mice were irradiated with different single and fractionated regimens. The single fraction dose was 10, 20, 30, 40 and 60 Gy, respectively. The fractionated regimens were 2 Gy x 5 fractions ( irradiated every day), and 3 Gy x 3 fractions (irradiated every other day), 3 Gy x 5 fractions (irradiated every day) and 4 Gy x 3 fractions (irradiated every other day), with total doses of 125 Gy, 114 Gy, 126 Gy and 112 Gy, respectively. The growth curve was used to evaluate the tumor doubling time. clonogenic assays was performed to draw the cell survival curve and analyze the radiobiological parameters with doses of 1, 2, 4, 6, 8 and 10 Gy. T 1/2 was measured by comet assay. Results: Tumor regression were not observed by single fraction irradiation, 2 Gy x 5 fractions and 3 Gy x 3 fractions irradiation regimens. The tumor regress was more significant with the increas of fraction dose. The 4 Gy x 3 fractions inhibited tumor more though not curing tumor. The cell doubling time of the BT 325 cell was 30. 16 h and the tumor doubling time of the xenograft was 43 days.When fitted with L-Q model, α was 0. 36 Gy -1 and β was 0. 057 Gy -2 . When fitted with the single-hit multi target model, D 0 was 1. 394 Gy, Dq was 2. 127 Gy and SF 2 was 0.714, respectively. The T 1/2 was 9.999 min. Conclusions: Glioma is a radioresistant tumor. Increase of the fraction dose improves recent effect.Further study is needed to control the tumor stem cells. (authors)

  16. Cellular Mechanisms of Action of Drug Abuse on Olfactory Neurons

    Directory of Open Access Journals (Sweden)

    Thomas Heinbockel

    2015-12-01

    Full Text Available Cannabinoids (Δ9-tetrahydrocannabinol are the active ingredient of marijuana (cannabis which is the most commonly abused illicit drug in the USA. In addition to being known and used as recreational drugs, cannabinoids are produced endogenously by neurons in the brain (endocannabinoids and serve as important signaling molecules in the nervous system and the rest of the body. Cannabinoids have been implicated in bodily processes both in health and disease. Recent pharmacological and physiological experiments have described novel aspects of classic brain signaling mechanisms or revealed unknown mechanisms of cellular communication involving the endocannabinoid system. While several forms of signaling have been described for endocannabinoids, the most distinguishing feature of endocannabinoids is their ability to act as retrograde messengers in neural circuits. Neurons in the main olfactory bulb express high levels of cannabinoid receptors. Here, we describe the cellular mechanisms and function of this novel brain signaling system in regulating neural activity at synapses in olfactory circuits. Results from basic research have the potential to provide the groundwork for translating the neurobiology of drug abuse to the realm of the pharmacotherapeutic treatment of addiction, specifically marijuana substance use disorder.

  17. Action-based mechanisms of attention.

    OpenAIRE

    Tipper, S P; Howard, L A; Houghton, G

    1998-01-01

    Actions, which have effects in the external world, must be spatiotopically represented in the brain. The brain is capable of representing space in many different forms (e.g. retinotopic-, environment-, head- or shoulder-centred), but we maintain that actions are represented in action-centred space, meaning that, at the cellular level, the direction of movement is defined by the activity of cells. In reaching, for example, object location is defined as the direction and distance between the or...

  18. Philosophy of veterinary radiobiology twenty years after the Chernobyl disaster

    International Nuclear Information System (INIS)

    Dvorak, P.; Toropila, M.

    2006-01-01

    The basic objective is to provide safe foodstuffs. This approach has connection with the food chain protection including the diagnostics and the acute radiation disease therapy at the farm animals. The extra significance is given to the research of technologies which can reduce the activity of the contaminated foodstuffs. In the field of the ionizing radiation effect research in live organisms attention should be devoted to the new alternative bio-tests. The low-dose effect or the interaction with other negative physical and chemical aspects of the environment is mainly considered. In cooperation with human medicine, it is necessary to develop radiotherapy and to study the effects of therapy and radiotherapy. From the standpoint of perspective technologies, it is advisable to focus on irradiation of the foodstuffs in veterinary radiobiology. (authors)

  19. Molecular substrates of action control in cortico-striatal circuits.

    Science.gov (United States)

    Shiflett, Michael W; Balleine, Bernard W

    2011-09-15

    The purpose of this review is to describe the molecular mechanisms in the striatum that mediate reward-based learning and action control during instrumental conditioning. Experiments assessing the neural bases of instrumental conditioning have uncovered functional circuits in the striatum, including dorsal and ventral striatal sub-regions, involved in action-outcome learning, stimulus-response learning, and the motivational control of action by reward-associated cues. Integration of dopamine (DA) and glutamate neurotransmission within these striatal sub-regions is hypothesized to enable learning and action control through its role in shaping synaptic plasticity and cellular excitability. The extracellular signal regulated kinase (ERK) appears to be particularly important for reward-based learning and action control due to its sensitivity to combined DA and glutamate receptor activation and its involvement in a range of cellular functions. ERK activation in striatal neurons is proposed to have a dual role in both the learning and performance factors that contribute to instrumental conditioning through its regulation of plasticity-related transcription factors and its modulation of intrinsic cellular excitability. Furthermore, perturbation of ERK activation by drugs of abuse may give rise to behavioral disorders such as addiction. Copyright © 2011 Elsevier Ltd. All rights reserved.

  20. Model for radiation damage in cells by direct effect and by indirect effect: a radiation chemistry approach

    International Nuclear Information System (INIS)

    Michaels, H.B.; Hunt, J.W.

    1978-01-01

    A model is presented to describe the contributions of direct and indirect effects to the radiation damage of cells. The model is derived using principles of radiation chemistry and of pulse radiolysis in particular. From data available in the literature, parameters for cellular composition and values of rate constants for indirect action have been used in preliminary applications of the model. The results obtained in calculations of the protective effect of .OH and .H scavengers are consistent with experimental data. Possible modifications and improvements to the model are suggested, along with proposed future applications of the model in radiobiological studies

  1. Tcp and NTCP radiobiological models: conventional and hypo fractionated treatments in radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Astudillo V, A.; Paredes G, L. [ININ, Carretera Mexico-Toluca s/n, Ocoyoacac 52750, Estado de Mexico (Mexico); Resendiz G, G.; Posadas V, A. [Hospital Angeles Lomas, Av. Vialidad de la Barranca s/n, Col. Valle de las Palmas, 52763 Huixquilucan de Degallado, Estado de Mexico (Mexico); Mitsoura, E. [Universidad Autonoma del Estado de Mexico, Facultad de Medicina, Paseo Tollocan, Esq. Jesus Carranza s/n, Col. Moderna de la Cruz, 50180 Toluca, Estado de Mexico (Mexico); Rodriguez L, A.; Flores C, J. M., E-mail: armando.astudillo@inin.gob.mx [Hospital Medica Sur, Puente de Piedra 150, Col. Toriello Guerra, 14050 Tlalpan, Mexico D. F. (Mexico)

    2015-10-15

    The hypo and conventional fractionated schedules performance were compared in terms of the tumor control and the normal tissue complications. From the records of ten patients, treated for adenocarcinoma and without mastectomy, the dose-volume histogram was used. Using radiobiological models the probabilities for tumor control and normal tissue complications were calculated. For both schedules the tumor control was approximately the same. However, the damage in the normal tissue was larger in conventional fractionated schedule. This is important because patients assistance time to their fractions (15 fractions/25 fractions) can be optimized. Thus, the hypo fractionated schedule has suitable characteristics to be implemented. (Author)

  2. Tcp and NTCP radiobiological models: conventional and hypo fractionated treatments in radiotherapy

    International Nuclear Information System (INIS)

    Astudillo V, A.; Paredes G, L.; Resendiz G, G.; Posadas V, A.; Mitsoura, E.; Rodriguez L, A.; Flores C, J. M.

    2015-10-01

    The hypo and conventional fractionated schedules performance were compared in terms of the tumor control and the normal tissue complications. From the records of ten patients, treated for adenocarcinoma and without mastectomy, the dose-volume histogram was used. Using radiobiological models the probabilities for tumor control and normal tissue complications were calculated. For both schedules the tumor control was approximately the same. However, the damage in the normal tissue was larger in conventional fractionated schedule. This is important because patients assistance time to their fractions (15 fractions/25 fractions) can be optimized. Thus, the hypo fractionated schedule has suitable characteristics to be implemented. (Author)

  3. SU-E-T-399: Determination of the Radiobiological Parameters That Describe the Dose-Response Relations of Xerostomia and Disgeusia From Head and Neck Radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Mavroidis, P; Stathakis, S; Papanikolaou, N [University of Texas Health Science Center, UTHSCSA, San Antonio, TX (United States); Peixoto Xavier, C [University of Coimbra, Coimbra, Coimbra (Portugal); Costa Ferreira, B [University of Aveiro, Coimbra, Coimbra (Portugal); Khouri, L; Carmo Lopes, M do [IPOCFG, EPE, Coimbra, Coimbra (Portugal)

    2014-06-01

    Purpose: To estimate the radiobiological parameters that describe the doseresponse relations of xerostomia and disgeusia from head and neck cancer radiotherapy. To identify the organs that are best correlated with the manifestation of those clinical endpoints. Finally, to evaluate the goodnessof- fit by comparing the model predictions against the actual clinical results. Methods: In this study, 349 head and neck cancer patients were included. For each patient the dose volume histograms (DVH) of parotids (separate and combined), mandible, submandibular glands (separate and combined) and salivary glands were calculated. The follow-up of those patients was recorded at different times after the completion of the treatment (7 weeks, 3, 7, 12, 18 and 24 months). Acute and late xerostomia and acute disgeusia were the clinical endpoints examined. A maximum likelihood fitting was performed to calculate the best estimates of the parameters used by the relative seriality model. The statistical methods of the error distribution, the receiver operating characteristic (ROC) curve, the Pearson's test and the Akaike's information criterion were utilized to assess the goodness-of-fit and the agreement between the pattern of the radiobiological predictions with that of the clinical records. Results: The estimated values of the radiobiological parameters of salivary glands are D50 = 25.2 Gy, γ = 0.52, s = 0.001. The statistical analysis confirmed the clinical validity of those parameters (area under the ROC curve = 0.65 and AIC = 38.3). Conclusion: The analysis proved that the treatment outcome pattern of the patient material can be reproduced by the relative seriality model and the estimated radiobiological parameters. Salivary glands were found to have strong volume dependence (low relative seriality). Diminishing the biologically effective uniform dose to salivary glands below 30 Gy may significantly reduce the risk of complications to the patients irradiated for

  4. SU-E-T-399: Determination of the Radiobiological Parameters That Describe the Dose-Response Relations of Xerostomia and Disgeusia From Head and Neck Radiotherapy

    International Nuclear Information System (INIS)

    Mavroidis, P; Stathakis, S; Papanikolaou, N; Peixoto Xavier, C; Costa Ferreira, B; Khouri, L; Carmo Lopes, M do

    2014-01-01

    Purpose: To estimate the radiobiological parameters that describe the doseresponse relations of xerostomia and disgeusia from head and neck cancer radiotherapy. To identify the organs that are best correlated with the manifestation of those clinical endpoints. Finally, to evaluate the goodnessof- fit by comparing the model predictions against the actual clinical results. Methods: In this study, 349 head and neck cancer patients were included. For each patient the dose volume histograms (DVH) of parotids (separate and combined), mandible, submandibular glands (separate and combined) and salivary glands were calculated. The follow-up of those patients was recorded at different times after the completion of the treatment (7 weeks, 3, 7, 12, 18 and 24 months). Acute and late xerostomia and acute disgeusia were the clinical endpoints examined. A maximum likelihood fitting was performed to calculate the best estimates of the parameters used by the relative seriality model. The statistical methods of the error distribution, the receiver operating characteristic (ROC) curve, the Pearson's test and the Akaike's information criterion were utilized to assess the goodness-of-fit and the agreement between the pattern of the radiobiological predictions with that of the clinical records. Results: The estimated values of the radiobiological parameters of salivary glands are D50 = 25.2 Gy, γ = 0.52, s = 0.001. The statistical analysis confirmed the clinical validity of those parameters (area under the ROC curve = 0.65 and AIC = 38.3). Conclusion: The analysis proved that the treatment outcome pattern of the patient material can be reproduced by the relative seriality model and the estimated radiobiological parameters. Salivary glands were found to have strong volume dependence (low relative seriality). Diminishing the biologically effective uniform dose to salivary glands below 30 Gy may significantly reduce the risk of complications to the patients irradiated for

  5. Radiobiological considerations in magna-field irradiation

    International Nuclear Information System (INIS)

    Evans, R.G.

    1983-01-01

    Radiobiological considerations are described for total body irradiation (TBI) as given to patients undergoing bone marrow transplantation (BMT). Although much progress has been made in the use of BMT for refractory leukemias, many patients still die from interstitial pneumonia and relapse. Fractionated TBI has been introduced in order to improve leukemic cell kill, while increasing the degree of normal tissue tolerance. Traditionally, bone marrow stem cells, leukemic cells and immunocytes have been considered as having a limited ability to repair radiation damage while cells of lung tissue and intestinal epithelial cells have a greater capacity. During fractionated radiation therapy or continuous low-dose rate exposure, repair of sublethal damage between fractions allows greater recovery in the cells of lung tissue to those in the bone marrow. Clinically, the potential benefit of six fractions over one fraction or low dose-rate TBI has yet to be proved, although there is suggestive evidence for a reduced incidence of interstitial pneumonitis. However, other extraneous factors such as doses to the lung, differences in conditioning regimens, effect of increased delay in BMT for patients receiving fractionated TBI, and the unmeasurable differences between institutions make definite conclusions impossible. Despite this, a consensus for dose fractionation has developed and most centers are moving away from the use of large single dose TBI

  6. The linearity of quantum mechanics from the perspective of Hamiltonian cellular automata

    International Nuclear Information System (INIS)

    Enrico Fermi, Università di Pisa, Largo Pontecorvo 3, I-56127 Pisa (Italy))" data-affiliation=" (Dipartimento di Fisica Enrico Fermi, Università di Pisa, Largo Pontecorvo 3, I-56127 Pisa (Italy))" >Elze, Hans-Thomas

    2014-01-01

    We discuss the action principle and resulting Hamiltonian equations of motion for a class of integer-valued cellular automata introduced recently [1]. Employing sampling theory, these deterministic finite-difference equations are mapped reversibly on continuum equations describing a set of bandwidth limited harmonic oscillators. They represent the Schrödinger equation. However, modifications reflecting the bandwidth limit are incorporated, i.e., the presence of a time (or length) scale. When this discreteness scale is taken to zero, the usual results are obtained. Thus, the linearity of quantum mechanics can be traced to the postulated action principle of such cellular automata and its conservation laws to discrete ones. The cellular automaton conservation laws are in one-to-one correspondence with those of the related quantum mechanical model, while admissible symmetries are not.

  7. Determination of the accuracy for targeted irradiations of cellular substructures at SNAKE

    Energy Technology Data Exchange (ETDEWEB)

    Siebenwirth, C. [Department of Radiation Oncology, Klinikum rechts der Isar, Technische Universität München, Munich (Germany); Institut für Angewandte Physik und Messtechnik (LRT2), Universität der Bundeswehr München, Neubiberg (Germany); Greubel, C. [Institut für Angewandte Physik und Messtechnik (LRT2), Universität der Bundeswehr München, Neubiberg (Germany); Drexler, S.E. [Department of Radiation Oncology, Ludwig-Maximilians-Universität München, Munich (Germany); Girst, S.; Reindl, J. [Institut für Angewandte Physik und Messtechnik (LRT2), Universität der Bundeswehr München, Neubiberg (Germany); Walsh, D.W.M. [Institut für Angewandte Physik und Messtechnik (LRT2), Universität der Bundeswehr München, Neubiberg (Germany); Department of Radiation Oncology, Klinikum rechts der Isar, Technische Universität München, Munich (Germany); Dollinger, G. [Institut für Angewandte Physik und Messtechnik (LRT2), Universität der Bundeswehr München, Neubiberg (Germany); Friedl, A.A. [Department of Radiation Oncology, Ludwig-Maximilians-Universität München, Munich (Germany); and others

    2015-04-01

    In the last 10 years the ion microbeam SNAKE, installed at the Munich 14 MV tandem accelerator, has been successfully used for radiobiological experiments by utilizing pattern irradiation without targeting single cells. Now for targeted irradiation of cellular substructures a precise irradiation device was added to the live cell irradiation setup at SNAKE. It combines a sub-micrometer single ion irradiation facility with a high resolution optical fluorescence microscope. Most systematic errors can be reduced or avoided by using the same light path in the microscope for beam spot verification as well as for and target recognition. In addition online observation of the induced cellular responses is possible. The optical microscope and the beam delivering system are controlled by an in-house developed software which integrates the open-source image analysis software, CellProfiler, for semi-automatic target recognition. In this work the targeting accuracy was determined by irradiation of a cross pattern with 55 MeV carbon ions on nucleoli in U2OS and HeLa cells stably expressing a GFP-tagged repair protein MDC1. For target recognition, nuclei were stained with Draq5 and nucleoli were stained with Syto80 or Syto83. The damage response was determined by live-cell imaging of MDC1-GFP accumulation directly after irradiation. No systematic displacement and a random distribution of about 0.7 μm (SD) in x-direction and 0.8 μm (SD) in y-direction were observed. An independent analysis after immunofluorescence staining of the DNA damage marker yH2AX yielded similar results. With this performance a target with a size similar to that of nucleoli (i.e. a diameter of about 3 μm) is hit with a probability of more than 80%, which enables the investigation of the radiation response of cellular subcompartments after targeted ion irradiation in the future.

  8. Determination of the accuracy for targeted irradiations of cellular substructures at SNAKE

    International Nuclear Information System (INIS)

    Siebenwirth, C.; Greubel, C.; Drexler, S.E.; Girst, S.; Reindl, J.; Walsh, D.W.M.; Dollinger, G.; Friedl, A.A.

    2015-01-01

    In the last 10 years the ion microbeam SNAKE, installed at the Munich 14 MV tandem accelerator, has been successfully used for radiobiological experiments by utilizing pattern irradiation without targeting single cells. Now for targeted irradiation of cellular substructures a precise irradiation device was added to the live cell irradiation setup at SNAKE. It combines a sub-micrometer single ion irradiation facility with a high resolution optical fluorescence microscope. Most systematic errors can be reduced or avoided by using the same light path in the microscope for beam spot verification as well as for and target recognition. In addition online observation of the induced cellular responses is possible. The optical microscope and the beam delivering system are controlled by an in-house developed software which integrates the open-source image analysis software, CellProfiler, for semi-automatic target recognition. In this work the targeting accuracy was determined by irradiation of a cross pattern with 55 MeV carbon ions on nucleoli in U2OS and HeLa cells stably expressing a GFP-tagged repair protein MDC1. For target recognition, nuclei were stained with Draq5 and nucleoli were stained with Syto80 or Syto83. The damage response was determined by live-cell imaging of MDC1-GFP accumulation directly after irradiation. No systematic displacement and a random distribution of about 0.7 μm (SD) in x-direction and 0.8 μm (SD) in y-direction were observed. An independent analysis after immunofluorescence staining of the DNA damage marker yH2AX yielded similar results. With this performance a target with a size similar to that of nucleoli (i.e. a diameter of about 3 μm) is hit with a probability of more than 80%, which enables the investigation of the radiation response of cellular subcompartments after targeted ion irradiation in the future

  9. Lipopolysaccharide recognition, internalisation, signalling and other cellular effects

    NARCIS (Netherlands)

    Diks, S. H.; van Deventer, S. J.; Peppelenbosch, M. P.

    2001-01-01

    Despite the importance of bacterial lipopolysaccharide (LPS) in infection and inflammation, many aspects of LPS action remain poorly understood. Especially, the mechanisms by which cells recognise and react to endotoxins or endotoxin-containing particles and how cellular responses are translated

  10. High value of the radiobiological parameter Dq correlates to expression of the transforming growth factor beta type II receptor in a panel of small cell lung cancer cell lines

    DEFF Research Database (Denmark)

    Hougaard, S; Krarup, M; Nørgaard, P

    1998-01-01

    Our panel of SCLC cell lines have previously been examined for their radiobiological characteristics and sensitivity to treatment with TGF beta 1. In this study we examined the possible correlations between radiobiological parameters and the expression of the TGF beta type II receptor (TGF beta......-rII). We have, in other studies, shown that the presence of TGF beta-rII was mandatory for transmitting the growth inhibitory effect of TGF beta. The results showed a statistically significant difference in Dq, i.e. the shoulder width of the survival curve, between cell lines expressing TGF beta......-rII and cell lines which did not express the receptor (P = 0.01). Cell lines expressing TGF beta-rII had a high Dq-value. TGF beta-rII expression did not correlate with any other radiobiological parameters. We suggest that an intact growth inhibitory pathway mediated by the TGF beta-rII may have a significant...

  11. Environmental Research Division annual report: Center for Human Radiobiology, July 1982-June 1983

    International Nuclear Information System (INIS)

    1984-03-01

    This is the fourteenth Annual Report of the Center for Human Radiobiology. New cases of bone cancer and carcinoma of head sinuses are occurring at a rate of about one per year in patients who acquired radium burdens 50 to 60 years ago. Several papers deal with dosimetry of alpha-emitting radionuclides in man, in animals, or in the environment. The report concludes with an appendix containing data on the exposure of 2312 persons whose radium content has been determined and an appendix listing the classical radium-related malignancies (osteosarcomas and carcinomas of the paranasal sinuses and mastoid)

  12. Research in radiobiology: Annual report of work in progress in the internal irradiation program

    International Nuclear Information System (INIS)

    Miller, S.C.; Buster, D.S.

    1987-01-01

    In the early 1950's the Atomic Energy Commission established at the University of Utah a large, long-term study designed to investigate the toxicity of internally deposited radionuclides in beagles. The first animals were injected on December 1, 1952 and thus began an odyssey unusual in modern science both for its duration and continued scientific interest and relevance. The original dogs were injected with 239 Pu and 226 Ra. Later, studies were initiated with 241 Am, 249 Cf, 252 Cf, 253 Es, 224 Ra, 228 Ra, 90 Sr, and 228 Th. These studies were unique and have and will continue to contribute valuable scientific information on the behavior and effects of these substances in biological systems. We feel that the data collected from these studies will be useful for many decades to come as we ask more demanding questions relative to radionuclides and environmental, biological and health issues. While this publication will be the last of our series Research in Radiobiology, the lifespan carcinogenesis studies are continuing under a collaborative arrangement with the I.T.R.I. Beginning in 1988, the colony status tables of dogs in the Utah studies and reports of research by the Radiobiology faculty will be included in the annual I.T.R.I. report. Under our new collaborative arrangements with the I.T.R.I. for the conduct of the lifespan carcinogenesis studies, we expect a continued high level of scientific productivity from our faculty

  13. Magnetic Hyperthermia and Radiation Therapy: Radiobiological Principles and Current Practice †

    Directory of Open Access Journals (Sweden)

    Spiridon V. Spirou

    2018-06-01

    Full Text Available Hyperthermia, though by itself generally non-curative for cancer, can significantly increase the efficacy of radiation therapy, as demonstrated by in vitro, in vivo, and clinical results. Its limited use in the clinic is mainly due to various practical implementation difficulties, the most important being how to adequately heat the tumor, especially deep-seated ones. In this work, we first review the effects of hyperthermia on tissue, the limitations of radiation therapy and the radiobiological rationale for combining the two treatment modalities. Subsequently, we review the theory and evidence for magnetic hyperthermia that is based on magnetic nanoparticles, its advantages compared with other methods of hyperthermia, and how it can be used to overcome the problems associated with traditional techniques of hyperthermia.

  14. Construction of cell model of silenced Ku80 and the radiobiology change of HeLa cell

    International Nuclear Information System (INIS)

    Zhuang Liang; Yu Shiying; Huang Xiaoyuan; Xiong Huihua; Xiong Hua; Li Xiaolan; Leng Yan

    2007-01-01

    Objective: To construct the cell model of Ku80 with expression inhibited by siRNA and to explore the role of Ku80 in radiobiology. Methods: Ku80-siRNA expression plasmids were constructed and HeLa cells were transfected with these plasmids by lipofectamine. Western blotting was used to measure the expression of Ku80. After irradiation with 6 MV X ray, cells were collected and analyzed by flow cytometry for apoptosis and cell cycle at 24, 48 and 72 h; The radiobiology parameters of four cell lines were acquired by clone formation array. Results: Three stable transfected cell clones were obtained, and the inhibition rates of Ku80 protein expression of two positive clones were 89.3% and 96.4%; The apoptosis rates of HeLa cells Ku80 inhibited were higher than control cells at 48 and 72 after X ray irradiation (P 0.05). HeLa cells of silenced Ku80 had lower SF 2 and D 0 than control cells, and their SER (sensitization enhancement ratio) based on D 10 were 1.315 and 1.365, respectively. Conclusions: The HeLa cell models with Ku80 expression suppressed were successfully established; the inhibition of Ku80 by siRNA could enhance the radiosensitivity of HeLa cells. (authors)

  15. Radiobiological and PK assays at advance Centre for Training Research and Education in Cancer (ACTREC)

    International Nuclear Information System (INIS)

    Sastri, Goda Jayant; Gota, Vikram

    2014-01-01

    Radiobiological, pharmacokinetic and biodistribution studies are of paramount importance for drug development and more so in the development of newer radiation modulators. Radiobiological studies have now graduated from simple cell survival and viability assays to more complex molecular and imaging studies to study radiation modulation both in in-vitro and in-vivo models. Tata Memorial Centre and its research centre (ACTREC) is a premiere cancer centre in India dedicated to cancer research. The Department of Radiation Oncology treats approximately 7000 new patients in a year and is uniquely placed to do both translational radiation and clinical research in the field of drug development. The Clinical Biology Lab of the Department of Radiation Oncology at ACTREC in collaboration with other labs at ACTREC has standardized cell survival assays, DNA damage assays such as Gamma H2AX assay (by flow as well as confocal microscopy), Micronuclei assay and COMET assays using CASP software for quantification. We have also done apoptotic assays. These assays have been conducted for development newer drug formulations (for e.g liposomal radiosensitizers). We also have a strong imaging division having sophisticated microscopes (confocal and single molecule super resolution microscopes) for in-vitro optical imaging and a dedicated preclinical PET/CT/SPECT for in-vivo imaging. The clinical 3T MRI and PET/CT is being used to study the effect of hypoxia in various cancers

  16. Light ions radiobiological effects on human tumoral cells: measurements modelling and application to hadron-therapy

    International Nuclear Information System (INIS)

    Jalade, P.

    2005-11-01

    In classical radiotherapy, the characteristics of photons interactions undergo limits for the treatment of radioresistant and not well located tumours. Pioneering treatments of patients at the Lawrence Laboratory at Berkeley has demonstrated two advantages of hadrons beams: the Relative Biologic Effect (the RBE) and the ballistic of the beams. Since 1994, the clinical centre at Chiba, has demonstrated successfully the applicability of the method. A physics group, managed by G. Kraft, at Darmstadt in Germany, has underlined the advantages of carbon beams. An European pool, called ENGIGHT (European Network for LIGHt ion Therapy) has been created in which the French ETOILE project appeared. The purpose of the thesis concerns measurements and models of 'in vitro' human cells survival. In the first part, the nowadays situation in particles interactions, tracks and cells structures and radiobiology is presented here. The second is devoted to the models based on the beam tracks and localization of the physical dose. Discussion of sensitivity to various parameters of the model has been realized with the help of numerical simulations. Finally the predictions of the improved model has been compared to experimental irradiations of human cells with argon and carbon beams of the GANIL machine. Conclusion of such study shows the performance and limits of a local model for predicting the radiobiological efficiency of light ions in hadron-therapy. (author)

  17. An Estimation of Radiobiological Parameters for Head-and-Neck Cancer Cells and the Clinical Implications

    International Nuclear Information System (INIS)

    Qi, X. Sharon; Yang, Qiuhui; Lee, Steve P.; Li, X. Allen; Wang, Dian

    2012-01-01

    In vitro survival measurements using two human head-and-neck cancer (HNC) cell lines were performed. The specially designed split-dose surviving fraction was obtained and fitted to the linear-quadratic formalism. The repair halftime (Tr), the potential doubling time (T d ), α/β and radiosensitivity α, were estimated. Other radiobiological models: EUD, BED, TCP, etc., were used to examine the potential treatment effectiveness of different IMRT techniques. Our data indicated the repair halftime of ~17 min based on two HNC cell lines. The combined α/β, α and T d are α/β = 8.1 ± 4.1 Gy, α = 0.22 ± 0.08 Gy −1 , T d = 4.0 ± 1.8 day, respectively. The prolonged IMRT dose delivery for entire HNC treatment course could possibly result in the loss of biological effectiveness, i.e., the target EUDs decreased by 11% with fraction dose delivery time varying from 5 to 30 min. We determined the sublethal damage repair halftime and other radiobiological parameters for HNC cells, and to evaluate treatment effectiveness of the prolonged dose delivery times associated with different IMRT techniques. The estimated repair halftime for HNC is relatively short and may be comparable to the step-and-shoot IMRT fraction dose delivery time. The effectiveness of IMRT treatment may be improved by reducing the fraction delivery time for HNC treatment

  18. Limitations of a convolution method for modeling geometric uncertainties in radiation therapy: the radiobiological dose-per-fraction effect

    International Nuclear Information System (INIS)

    Song, William; Battista, Jerry; Van Dyk, Jake

    2004-01-01

    The convolution method can be used to model the effect of random geometric uncertainties into planned dose distributions used in radiation treatment planning. This is effectively done by linearly adding infinitesimally small doses, each with a particular geometric offset, over an assumed infinite number of fractions. However, this process inherently ignores the radiobiological dose-per-fraction effect since only the summed physical dose distribution is generated. The resultant potential error on predicted radiobiological outcome [quantified in this work with tumor control probability (TCP), equivalent uniform dose (EUD), normal tissue complication probability (NTCP), and generalized equivalent uniform dose (gEUD)] has yet to be thoroughly quantified. In this work, the results of a Monte Carlo simulation of geometric displacements are compared to those of the convolution method for random geometric uncertainties of 0, 1, 2, 3, 4, and 5 mm (standard deviation). The α/β CTV ratios of 0.8, 1.5, 3, 5, and 10 Gy are used to represent the range of radiation responses for different tumors, whereas a single α/β OAR ratio of 3 Gy is used to represent all the organs at risk (OAR). The analysis is performed on a four-field prostate treatment plan of 18 MV x rays. The fraction numbers are varied from 1-50, with isoeffective adjustments of the corresponding dose-per-fractions to maintain a constant tumor control, using the linear-quadratic cell survival model. The average differences in TCP and EUD of the target, and in NTCP and gEUD of the OAR calculated from the convolution and Monte Carlo methods reduced asymptotically as the total fraction number increased, with the differences reaching negligible levels beyond the treatment fraction number of ≥20. The convolution method generally overestimates the radiobiological indices, as compared to the Monte Carlo method, for the target volume, and underestimates those for the OAR. These effects are interconnected and attributed

  19. 7th International Workshop on Microbeam Probes of Cellular Radiation Response

    Energy Technology Data Exchange (ETDEWEB)

    Brenner, David J.

    2009-07-21

    The extended abstracts that follow present a summary of the Proceedings of the 7th International Workshop: Microbeam Probes of Cellular Radiation Response, held at Columbia University’s Kellogg Center in New York City on March 15–17, 2006. These International Workshops on Microbeam Probes of Cellular Radiation Response have been held regularly since 1993 (1–5). Since the first workshop, there has been a rapid growth (see Fig. 1) in the number of centers developing microbeams for radiobiological research, and worldwide there are currently about 30 microbeams in operation or under development. Single-cell/single-particle microbeam systems can deliver beams of different ionizing radiations with a spatial resolution of a few micrometers down to a few tenths of a micrometer. Microbeams can be used to addressquestions relating to the effects of low doses of radiation (a single radiation track traversing a cell or group of cells), to probe subcellular targets (e.g. nucleus or cytoplasm), and to address questions regarding the propagation of information about DNA damage (for example, the radiation-induced bystander effect). Much of the recent research using microbeams has been to study low-dose effects and ‘‘non-targeted’’ responses such as bystander effects, genomic instability and adaptive responses. This Workshop provided a forum to assess the current state of microbeam technology and current biological applications and to discuss future directions for development, both technological and biological. Over 100 participants reviewed the current state of microbeam research worldwide and reported on new technological developments in the fields of both physics and biology.

  20. Radiobiologic comparison of helical tomotherapy, intensity modulated radiotherapy, and conformal radiotherapy in treating lung cancer accounting for secondary malignancy risks

    Energy Technology Data Exchange (ETDEWEB)

    Komisopoulos, Georgios [Department of Medical Physics, Medical School, University of Patras, Patras (Greece); Mavroidis, Panayiotis, E-mail: mavroidis@uthscsa.edu [Department of Radiation Oncology, University of Texas Health Sciences Center at San Antonio, San Antonio, TX (United States); Department of Medical Radiation Physics, Karolinska Institutet and Stockholm University, Stockholm (Sweden); Rodriguez, Salvador; Stathakis, Sotirios; Papanikolaou, Nikos [Department of Radiation Oncology, University of Texas Health Sciences Center at San Antonio, San Antonio, TX (United States); Nikiforidis, Georgios C.; Sakellaropoulos, Georgios C. [Department of Medical Physics, Medical School, University of Patras, Patras (Greece)

    2014-01-01

    The aim of the present study is to examine the importance of using measures to predict the risk of inducing secondary malignancies in association with the clinical effectiveness of treatment plans in terms of tumor control and normal tissue complication probabilities. This is achieved by using radiobiologic parameters and measures, which may provide a closer association between clinical outcome and treatment delivery. Overall, 4 patients having been treated for lung cancer were examined. For each of them, 3 treatment plans were developed based on the helical tomotherapy (HT), multileaf collimator-based intensity modulated radiation therapy (IMRT), and 3-dimensional conformal radiation therapy (CRT) modalities. The different plans were evaluated using the complication-free tumor control probability (p{sub +}), the overall probability of injury (p{sub I}), the overall probability of control/benefit (p{sub B}), and the biologically effective uniform dose (D{sup ¯¯}). These radiobiologic measures were used to develop dose-response curves (p-D{sup ¯¯} diagram), which can help to evaluate different treatment plans when used in conjunction with standard dosimetric criteria. The risks for secondary malignancies in the heart and the contralateral lung were calculated for the 3 radiation modalities based on the corresponding dose-volume histograms (DVHs) of each patient. Regarding the overall evaluation of the different radiation modalities based on the p{sub +} index, the average values of the HT, IMRT, and CRT are 67.3%, 61.2%, and 68.2%, respectively. The corresponding average values of p{sub B} are 75.6%, 70.5%, and 71.0%, respectively, whereas the average values of p{sub I} are 8.3%, 9.3%, and 2.8%, respectively. Among the organs at risk (OARs), lungs show the highest probabilities for complications, which are 7.1%, 8.0%, and 1.3% for the HT, IMRT, and CRT modalities, respectively. Similarly, the biologically effective prescription doses (D{sub B}{sup ¯¯}) for the

  1. Theoretical aspects of cellular decision-making and information-processing.

    Science.gov (United States)

    Kobayashi, Tetsuya J; Kamimura, Atsushi

    2012-01-01

    Microscopic biological processes have extraordinary complexity and variety at the sub-cellular, intra-cellular, and multi-cellular levels. In dealing with such complex phenomena, conceptual and theoretical frameworks are crucial, which enable us to understand seemingly different intra- and inter-cellular phenomena from unified viewpoints. Decision-making is one such concept that has attracted much attention recently. Since a number of cellular behavior can be regarded as processes to make specific actions in response to external stimuli, decision-making can cover and has been used to explain a broad range of different cellular phenomena [Balázsi et al. (Cell 144(6):910, 2011), Zeng et al. (Cell 141(4):682, 2010)]. Decision-making is also closely related to cellular information-processing because appropriate decisions cannot be made without exploiting the information that the external stimuli contain. Efficiency of information transduction and processing by intra-cellular networks determines the amount of information obtained, which in turn limits the efficiency of subsequent decision-making. Furthermore, information-processing itself can serve as another concept that is crucial for understanding of other biological processes than decision-making. In this work, we review recent theoretical developments on cellular decision-making and information-processing by focusing on the relation between these two concepts.

  2. SU-E-T-70: A Radiobiological Model of Reoxygenation and Fractionation Effects

    Energy Technology Data Exchange (ETDEWEB)

    Guerrero, M [University of Maryland School of Medicine, Baltimore, MD (United States); Carlson, DJ [Yale Univ. School of Medicine, New Haven, CT (United States)

    2015-06-15

    Purpose: To develop a simple reoxygenation model that fulfills the following goals:1-Quantify the reoxygenation effect in biologically effective dose (BED) and compare it to the repopulation effect.2-Model the hypoxic fraction in tumors as a function of the number of fractions.3-Develop a simple analytical expression for a reoxygenation term in BED calculations. Methods: The model considers tumor cells in two compartments: one normoxic population of cells and one hypoxic compartment including cells under a range of reduced oxygen concentrations. The surviving fraction is predicted using the linear-quadratic (LQ) model. A hypoxia reduction factor (HRF) is used to quantify reductions in radiosensitivity parameters α-A and β-A as cellular oxygen concentration decreases. The HRF is defined as the ratio of the dose at a specific level of hypoxia to the dose under fully aerobic conditions to achieve equal cell killing. The model assumes that a fraction of the hypoxic cells ( ) moves from the hypoxic to the aerobic compartment after each daily fraction. As an example, we consider standard fractionation for NSCLC (d=2Gy,n=33) versus a SBRT (n=5, d=10Gy) fractionation and compare the loss in reoxygenation biological effect with the gain in repopulation biological effect. Results: An analytic expression for the surviving fraction after n daily treatments is derived and the reoxygenation term in the biological effect is calculated. Reoxygenation and repopulation effects are the same order of magnitude for potential doubling time Td values of 2 to 5 days. The hypoxic fraction increases or decreases with n depending on the reoxygenation rate Δ. For certain combinations of parameters, the biological effect of reoxygenation goes as -(n-1)*ln(1-Δ) providing a simple expression that can be introduced in BED calculations. Conclusion: A novel radiobiological model was developed that can be used to evaluate the effect of reoxygenation in fractionated radiotherapy.

  3. Silver Nanoparticle-Mediated Cellular Responses in Various Cell Lines: An in Vitro Model

    Directory of Open Access Journals (Sweden)

    Xi-Feng Zhang

    2016-09-01

    Full Text Available Silver nanoparticles (AgNPs have attracted increased interest and are currently used in various industries including medicine, cosmetics, textiles, electronics, and pharmaceuticals, owing to their unique physical and chemical properties, particularly as antimicrobial and anticancer agents. Recently, several studies have reported both beneficial and toxic effects of AgNPs on various prokaryotic and eukaryotic systems. To develop nanoparticles for mediated therapy, several laboratories have used a variety of cell lines under in vitro conditions to evaluate the properties, mode of action, differential responses, and mechanisms of action of AgNPs. In vitro models are simple, cost-effective, rapid, and can be used to easily assess efficacy and performance. The cytotoxicity, genotoxicity, and biocompatibility of AgNPs depend on many factors such as size, shape, surface charge, surface coating, solubility, concentration, surface functionalization, distribution of particles, mode of entry, mode of action, growth media, exposure time, and cell type. Cellular responses to AgNPs are different in each cell type and depend on the physical and chemical nature of AgNPs. This review evaluates significant contributions to the literature on biological applications of AgNPs. It begins with an introduction to AgNPs, with particular attention to their overall impact on cellular effects. The main objective of this review is to elucidate the reasons for different cell types exhibiting differential responses to nanoparticles even when they possess similar size, shape, and other parameters. Firstly, we discuss the cellular effects of AgNPs on a variety of cell lines; Secondly, we discuss the mechanisms of action of AgNPs in various cellular systems, and try to elucidate how AgNPs interact with different mammalian cell lines and produce significant effects; Finally, we discuss the cellular activation of various signaling molecules in response to AgNPs, and conclude with

  4. Cell survivor: Modeling radiobiological phenomena with a new kind of simulation

    Science.gov (United States)

    Spencer, Melissa A.

    Despite widespread societal fear of radiation, whether justified or unjustified, and whether related to medicine (e.g., CT scans) or other forms of nuclear and atomic radiation (e.g., nuclear power) there is a fundamental lack of basic understanding of radiation effects on the human body. Different types of radiation are psychologically grouped into the same general fear category irrespective of their different potential to do harm, and this fear is not balanced by their potential beneficial effects. By modeling certain types of radiation biology experiments within a game engine, it is possible to enhance the player's intuitive understanding of radiobiology, both the effects of different types of radiation as well as different environmental factors that can enhance or suppress repair. For this dissertation, a game/simulation has been developed that intends to narrow the gap between public perception and the reality of these physical processes. The building blocks of this simulation are cells, which are damaged by incident radiation, accumulating either single or double strand breaks. They grow and reproduce, and are especially vulnerable during certain phases of the cell cycle (e.g. mitosis). Two dominant damage mechanisms are modeled, along with multiple repair mechanisms, for example, double strand breaks can be repaired by either non-homologous end joining or homologous repair. The output of the developed simulation was compared to data collected in experimental studies and the simulation appears to be a valid representation of the dominant mechanisms of radiobiology, as far as can be determined within the scope of this dissertation. Cell survival curves generated from playtest data display shoulders that depend on the LET of incident radiation, and rest time restores repair capability. In addition to public outreach, the presented code can be used to aid investigators by collecting data during play that can be used as a distributed Monte Carlo simulation

  5. Radiobiological inactivation of Epstein-Barr virus

    International Nuclear Information System (INIS)

    Henderson, E.; Heston, L.; Grogan, E.; Miller, G.

    1978-01-01

    Lymphocyte transforming properties of B95-8 strain Epstein-Barr virus (EBV) are very sensitive to inactivation by either uv or x irradiation. No dose of irradiation increases the transforming capacity of EBV. The x-ray dose needed for inactivation of EBV transformation (dose that results in 37% survival, 60,000 rads) is similar to the dose required for inactivation of plaque formation by herpes simplex virus type 1 (Fischer strain). Although herpes simplex virus is more sensitive than EBV to uv irradiation, this difference is most likely due to differences in the kinetics or mechanisms of repair of uv damage to the two viruses. The results lead to the hypothesis that a large part, or perhaps all, of the EBV genome is in some way needed to initiate transformation. The abilities of EBV to stimulate host cell DNA synthesis, to induce nuclear antigen, and to immortalize are inactivated in parallel. All clones of marmoset cells transformed by irradiated virus produce extracellular transforming virus. These findings suggest that the abilities of the virus to transform and to replicate complete progeny are inactivated together. The amounts of uv and x irradiation that inactivate transformation by B95-8 virus are less than the dose needed to inactivate early antigen induction by the nontransforming P 3 HR-1 strain of EBV. Based on radiobiological inactivation, 10 to 50% of the genome is needed for early antigen induction

  6. Hypo-fractionated treatment in radiotherapy: radio-biological models Tcp and NTCP

    International Nuclear Information System (INIS)

    Astudillo V, A. J.; Mitsoura, E.; Paredes G, L.; Resendiz G, G.

    2014-08-01

    At the present time the breast cancer in Mexico has the first place of incidence of the malignant neoplasia s in the women, and represents 11.34% of all the cancer cases. On the other hand, the treatments for cancer by means of ionizing radiations have been dominated under the approaches of the medical radio-oncologists which have been based on test and error by many years. The radio-biological models, as the Tcp, NTCP and dosimetric variables, for their clinical application in the conventional radiotherapy with hypo-fractionation have as purpose predicting personalized treatment plans that they present most probability of tumor control and minor probability of late reactions, becoming this way support tools in the decisions taking for the patient treatments planning of Medical Physicists and Radio-oncologists. (Author)

  7. Cellular and Molecular Aspects of the β-N-Methylamino-l-alanine (BMAA Mode of Action within the Neurodegenerative Pathway: Facts and Controversy

    Directory of Open Access Journals (Sweden)

    Nicolas Delcourt

    2017-12-01

    Full Text Available The implication of the cyanotoxin β-N-methylamino-l-alanine (BMAA in long-lasting neurodegenerative disorders is still a matter of controversy. It has been alleged that chronic ingestion of BMAA through the food chain could be a causative agent of amyotrophic lateral sclerosis (ALS and several related pathologies including Parkinson syndrome. Both in vitro and in vivo studies of the BMAA mode of action have focused on different molecular targets, demonstrating its toxicity to neuronal cells, especially motoneurons, and linking it to human neurodegenerative diseases. Historically, the hypothesis of BMAA-induced excitotoxicity following the stimulation of glutamate receptors has been established. However, in this paradigm, most studies have shown acute, rather than chronic effects of BMAA. More recently, the interaction of this toxin with neuromelanin, a pigment present in the nervous system, has opened a new research perspective. The issues raised by this toxin are related to its kinetics of action, and its possible incorporation into cellular proteins. It appears that BMAA neurotoxic activity involves different targets through several mechanisms known to favour the development of neurodegenerative processes.

  8. Cellular and molecular radiobiology of heavy-ion beams

    International Nuclear Information System (INIS)

    Tobias, C.A.; Blakely, E.A.; Ngo, F.Q.H.; Roots, R.J.; Yang, T.C.H.; Chang, P.Y.; Lommel, L.; Craise, L.M.; Yezzi, M.J.

    1982-01-01

    Accelerated heavy particles are candidates for use in cancer radiotherapy, and the major goal of our program has been to characterize the biological potential of Bevalac beams for this purpose. Relative biological effectiveness (RBE) values and oxygen enhancement ratio (OER) properties of monoenergetic carbon, neon, and argon beams with initial energies of several hundred MeV/u have been measured as a function of residual range. Bevalac beams with Bragg peaks modified to encompass tumors of various sizes have also been studied using cultured cells in vitro

  9. Research in radiobiology. Annual report of work in progress in the Internal Irradiation Program

    International Nuclear Information System (INIS)

    Miller, S.C.

    1980-01-01

    Survival data on 160 nonirradiated control beagles of the University of Utah's Radiobiology Laboratory were analyzed. The animals died during a period from 1958 into 1979. The average age at death of animals which died during the 1958 to 1965 interval was significantly less than that of those whose deaths occurred in the 1965 to 1979 interval. The best estimate for average age at death for Super-Selected nonirradiated control beagles of the colony is 4864 +- 901 days. The Super-Selected dogs excluded those dying because of epilepsy, lymphosarcoma, lymphoma or accidents, and also excluded all dogs dying before 1966

  10. Minimal entropy approximation for cellular automata

    International Nuclear Information System (INIS)

    Fukś, Henryk

    2014-01-01

    We present a method for the construction of approximate orbits of measures under the action of cellular automata which is complementary to the local structure theory. The local structure theory is based on the idea of Bayesian extension, that is, construction of a probability measure consistent with given block probabilities and maximizing entropy. If instead of maximizing entropy one minimizes it, one can develop another method for the construction of approximate orbits, at the heart of which is the iteration of finite-dimensional maps, called minimal entropy maps. We present numerical evidence that the minimal entropy approximation sometimes outperforms the local structure theory in characterizing the properties of cellular automata. The density response curve for elementary CA rule 26 is used to illustrate this claim. (paper)

  11. The Non-Genomic Actions of Vitamin D

    Directory of Open Access Journals (Sweden)

    Charles S Hii

    2016-03-01

    Full Text Available Since its discovery in 1920, a great deal of effort has gone into investigating the physiological actions of vitamin D and the impact its deficiency has on human health. Despite this intense interest, there is still disagreement on what constitutes the lower boundary of adequacy and on the Recommended Dietary Allowance. There has also been a major push to elucidate the biochemistry of vitamin D, its metabolic pathways and the mechanisms that mediate its action. Originally thought to act by altering the expression of target genes, it was realized in the mid-1980s that some of the actions of vitamin D were too rapid to be accounted for by changes at the genomic level. These rapid non-genomic actions have attracted as much interest as the genomic actions and they have spawned additional questions in an already busy field. This mini-review attempts to summarise the in vitro and in vivo work that has been conducted to characterise the rapid non-genomic actions, the mechanisms that give rise to these properties and the roles that these play in the overall action of vitamin D at the cellular level. Understanding the effects of vitamin D at the cellular level should enable the design of elegant human studies to extract the full potential of vitamin D to benefit human health.

  12. Experimental radiotherapy and clinical radiobiology. Vol. 22. Proceedings; Experimentelle Strahlentherapie und Klinische Strahlenbiologie. Bd. 25. Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Baumann, Michael; Krause, Mechthild [Universitaetsklinikum Technische Univ. Dresden (Germany). Klinik und Poliklinik fuer Strahlentherapie und Radiologie; Cordes, Nils [Universitaetsklinikum Technische Univ. Dresden (Germany). OncoRay - Nationales Zentrum fuer Strahlenforschung in der Radioonkologie; Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany); Petersen, Cordula [Universitaetsklinikum Hamburg-Eppendorf, Hamburg (Germany). Klinik und Poliklinik fuer Strahlentherapie und Radioonkologie; Rodemann, H. Peter [Universitaetsklinikum Tuebingen (Germany). Sektion fuer Strahlenbiologie; Rothkamm, Kai [Universitaetsklinikum Hamburg-Eppendorf, Hamburg (Germany). Lab. fuer Strahlentherapie und Experimentelle Radioonkologie; Zips, Daniel (ed.) [Tuebingen Univ. (Germany). Universitaetsklinik fuer Radioonkologie

    2016-05-01

    The proceedings of the 25th symposium on experimental radiotherapy and clinical radiobiology include papers on the following issues: radiotherapy individualization based on imaging; pre-clinic imaging and new experimental methods; methods and models, micromilieu and metabolism, combined therapy; secondary tumors following radiotherapy; radiogenic effects in normal tissue; resistance mechanism of tumors and normal tissue; personalized radio-oncology - which biological data are needed; pre-clinic and personalized radio-oncology; biomarkers - pre-clinic and translational; translational examinations for personalized radio-oncology.

  13. Experimental radiotherapy and clinical radiobiology. Vol. 18. Proceedings; Experimentelle Strahlentherapie und Klinische Strahlenbiologie. Bd. 18. Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Baumann, Michael; Dahm-Daphi, Jochen; Dikomey, Ekkehard; Petersen, Cordula; Rodemann, H Peter; Zips, Daniel [eds.

    2009-07-15

    The proceedings on experimental radiotherapy and clinical radiobiology contain two review articles (prediction of normal tissue reactions after radiotherapy, ?H2AX foci as a marker for DNA double-strand breaks) and 34 contributions to the following topics: Hypoxia and molecular mechanisms of radiation resistance; biological imaging of the tumor micromilieu; DNA repair, genomic instability and carcerogenesis; molecular factors of radiation resistance; actual controversial discussion on possible irradiation caused metastasis risk enhancement; EGFR inhibition and irradiation; biology of experimental radiation/ normal tissue toxicity.

  14. Photobiology of animal cells. Fotobiologiya zhivotnoi kletki

    Energy Technology Data Exchange (ETDEWEB)

    Troshin, A S; Krauzova, N F; Samoilova, K A

    1979-01-01

    A presentation is made of studies concerned with cellular and molecular mechanisms of joint and separate effects on the part of various components of solar radiation upon non-photosynthesizing organisms. An analysis is made of the action of ecological types of solar radiation, such as long-wave ultraviolet beams and those of visible light as well as the effect of laser radiation. The collection of articles will be of interest to biologists working in the field of photo- and radiobiology, cytology, molecular biology, genetics, experimental oncology, biophysics as well as to physicians and agricultural specialists who use optical radiation for therapeutic and sanitation purposes. 83 figures, 34 tables.

  15. Radiobiological characteristics of cervical cancer

    International Nuclear Information System (INIS)

    Kagabu, Teruo; Kobayashi, Takashi; Nanayama, Kunihiko

    1976-01-01

    In order to observe the radiobiological characteristics of cervical cancer, the author carried out irradiation of 60 Co in 16 cases of cervical cancer. The primary lesion of each case was exposed to radiation of 100 R once a day, 40 times in sequence, totaling 4,000 R. To evaluate this results, the vaginal smears were obtained everyday and examined for changes in cancerous cells caused by the irradiation. The results of our study showed that cervical cancer could be classified into three groups according to the radiosensitivity of its cancerous cells. In the group of low-radiosensitivity (11 cases of 16), the cancerous cells decreased gradually, and enlargement of the nuclei of the cancerous cells was observed from 2,000 R of irradiation, but the majority of the cancerous cells were those of nucleus after the irradiation of 4,000 R. In all of the 5 uterus removed, residual cancer lesion was noted. The radiocuability was unfavourable. In the group of high-radiosensitivity (4 cases of 16), the cancerous cells decreased remarkablly. Enlargement of nucleus was noted from 1,000 R of the irradiation, the cancerous cells of small-sized nucleus appeared with the irradiation of 3,000 R but the cancerous cells almost disappeared with the irradiation of 4,000 R. The radiocuability was favourable. In the group of combination of high-radiosensitivity and low-radiosensitivity portions (one case of 16), the cancerous cells decreased remarkablly until the exposure to the radiation of 2,000 R but thereafter did slowly. In a removed uterus, the cancer lesion was noted, but the prognosis was favourable. The foregoing results suggest that changes in the nuclear diameter of the cancerous cells in vaginal smears during irradiation can tell the radiosensitivity of the cancerous cells. (Kanao, N.)

  16. Cellular radiosensitivity of small-cell lung cancer cell lines

    DEFF Research Database (Denmark)

    Krarup, M; Poulsen, H S; Spang-Thomsen, M

    1997-01-01

    PURPOSE: The objective of this study was to determine the radiobiological characteristics of a panel of small-cell lung cancer (SCLC) cell lines by use of a clonogenic assay. In addition, we tested whether comparable results could be obtained by employing a growth extrapolation method based...

  17. Biochemical basis for the action of radioprotective drugs

    International Nuclear Information System (INIS)

    Romantsev, E.F.; Blokhina, V.D.; Zhulanova, Z.I.; Koshcheenko, N.N.; Filippovich, I.V.

    1977-01-01

    The hypothesis of complex biochemical mechanism of action of radioprotective drugs is described. Shortly after injection of radioprotective aminothiols into animals the inhibition of radiosensitive biochemical processes: DNA and RNA synthesis, protein synthesis and oxidative phosphorylation has been observed. The molecular mechanism of these phenomena consists of radioprotectors ability to form adsorption, thioester, amide, and disulphide bonds with appropriate enzymes. The curve reflecting the formation and breakdown of mixed disulphides between radioprotectors and proteins coincides well with that reflecting the radioprotective effect dependence on time. The radiobiological significance of molecular interactions observed may be interpreted as the diminution in ''spoiled'' molecules formation (inhibition of replication) and elevation in repartion rate. The inhibition of biochemical processes has the reversible nature and last for short time. The drugs acting according to so-called oxygen effect protect also by means of biochemical mechanisms. The molecular mechanism is mediated through their ability to bind to receptors, and biologically important molecules and macromolecules. As a result the inhibition of radiosensitive processes occurs, the ''spoiled'' molecules number is diminished and reparation takes place more easily. The idea on the complex biochemical mechanism of action of radioprotectors correlates with the proposal on complex biochemical mechanism responsible for interphase death occured after irradiation

  18. Radiobiological arguments for and clinical possibilities of unconventional fractionating rhythms

    International Nuclear Information System (INIS)

    Herrmann, T.; Voigtmann, L.

    1986-01-01

    Radiobiological considerations are presented using unconventional fractionating rhythms. The aim of this method is to enlarge the therapeutic dimensions between maximum tumor destruction and most careful treatment of late responding cell systems. These late responding tissues show a very similar dose-time reaction, probably by reason of a causal injury on cells of the capillary endothelium. In linear-quadratic models for the estimation of the parameters of the number of fractions and total treatment period it becomes evident that a careful treatment of late responding tissue can be attained by reduction of the single dose per fraction. Because with partition of a total dose in several fractions at daily irradiation a longer repopulation period is available also for the tumor irradiations are presented, done repeatedly during the day. Accelerated fractionation (same fractionating number in reduced treatment period) are contrasted to hyperfractionation (increased fractionating number within the same total treatment period) and possibilities in application are suggested. (author)

  19. Estimation of the radiobiological and kinetic factors of radiosensitivity and radiocurability of metastases of squamous cell carcinoma of the larynx to neck lymph nodes

    International Nuclear Information System (INIS)

    Maciejewski, B.

    1985-01-01

    The usefulness of theoretical model of tumour growth and experimental methods of kinetic and radiobiological factors for analysis of clinical data to improve the effectiveness of dose fractionation are checked. 176 refs., 27 figs., 19 tabs. (author)

  20. Radiobiological basis of SBRT and SRS.

    Science.gov (United States)

    Song, Chang W; Kim, Mi-Sook; Cho, L Chinsoo; Dusenbery, Kathryn; Sperduto, Paul W

    2014-08-01

    Stereotactic body radiation therapy (SBRT) and stereotactic radiosurgery (SRS) have been demonstrated to be highly effective for a variety of tumors. However, the radiobiological principles of SBRT and SRS have not yet been clearly defined. It is well known that newly formed tumor blood vessels are fragile and extremely sensitive to ionizing radiation. Various lines of evidence indicate that irradiation of tumors with high dose per fraction, i.e. >10 Gy per fraction, not only kills tumor cells but also causes significant damage in tumor vasculatures. Such vascular damage and ensuing deterioration of the intratumor environment then cause ischemic or indirect/secondary tumor cell death within a few days after radiation exposure, indicating that vascular damage plays an important role in the response of tumors to SBRT and SRS. Indications are that the extensive tumor cell death due to the direct effect of radiation on tumor cells and the secondary effect through vascular damage may lead to massive release of tumor-associated antigens and various pro-inflammatory cytokines, thereby triggering an anti-tumor immune response. However, the precise role of immune assault on tumor cells in SBRT and SRS has not yet been clearly defined. The "4 Rs" for conventional fractionated radiotherapy do not include indirect cell death and thus 4 Rs cannot account for the effective tumor control by SBRT and SRS. The linear-quadratic model is for cell death caused by DNA breaks and thus the usefulness of this model for ablative high-dose SBRT and SRS is limited.

  1. Comparison of volumetric modulated arc therapy and intensity modulated radiation therapy for whole brain hippocampal sparing treatment plans based on radiobiological modeling

    Directory of Open Access Journals (Sweden)

    Ethan Kendall

    2018-01-01

    Full Text Available Introduction: In this article, we report the results of our investigation on comparison of radiobiological aspects of treatment plans with linear accelerator-based intensity-modulated radiation therapy and volumetric-modulated arc therapy for patients having hippocampal avoidance whole-brain radiation therapy. Materials and Methods: In this retrospective study using the dose-volume histogram, we calculated and compared biophysical indices of equivalent uniform dose, tumor control probability, and normal tissue complication probability (NTCP for 15 whole-brain radiotherapy patients. Results and Discussions: Dose-response models for tumors and critical structures were separated into two groups: mechanistic and empirical. Mechanistic models formulate mathematically with describable relationships while empirical models fit data through empirical observations to appropriately determine parameters giving results agreeable to those given by mechanistic models. Conclusions: Techniques applied in this manuscript could be applied to any other organs or types of cancer to evaluate treatment plans based on radiobiological modeling.

  2. Radiobiological effects in organisms of plants and animals exposed to ionizing irradiation in the Chernobyl NPP zone

    International Nuclear Information System (INIS)

    Panchenko, N.A.; Arkhipov, N.P.; Alesina, M.Y.; Kuchma, V.I.; Gaschak, S.P.; Burov, N.I.

    1997-01-01

    Influence of ionizing radiation on forest ecosystems most clearly revealed itself near the Chernobyl NPP (ChNPP), were magnitudes of absorbed doses reached 'lethal' values, as applied to conifers. Main contribution to absorbed dose was due to beta-radiation of short-living radionuclides. To largest extent the radiobiological effects appeared at injured plantations of pines and firs. Nevertheless, during the first year maximum absorbed doses influenced also on leaf-bearing trees (birch, alder, asp) which then rehabilitated themselves completely

  3. Morphological differences in the response of mouse small intestine to radiobiologically equivalent doses of X and neutron irradiation

    International Nuclear Information System (INIS)

    Carr, K.E.; Hamlet, R.; Nias, A.H.; Watt, C.

    1984-01-01

    A scale has been developed to describe the effects of radiation on small intestinal villi. The scale has been used to compare the damage done to the villi in the period 0-5 days after irradiation by X-irradiation or neutron irradiation, using 10 Gy X-rays and 5 Gy neutrons, doses which are radiobiologically equivalent when assessed by the microcolony assay method. Use of the scale indicates that the damage done to the villi by neutrons is greater than that produced by X-rays. This has implications for the interpretation of radiobiological equivalent doses (R.B.E.). Resin light microscopy and transmission electron microscopy (T.E.M.) have also been used to examine small intestinal damage after 10 Gy X-irradiation and 5 Gy neutron irradiation. Differences include variations in crypt shape, mitotic activity and the proportion of crypts which are heavily parasitised. As well as the differences in villous shape which have been reflected in the different values on the scoring system, there are also variations in the response of the constituent cells of the epithelial compartment of the villi. In general, the effect of the neutron irradiation is more severe than that of the X-rays, particularly as would be suggested by a simple quantitation of crypt regeneration

  4. ‘Survival’: a simulation toolkit introducing a modular approach for radiobiological evaluations in ion beam therapy

    Science.gov (United States)

    Manganaro, L.; Russo, G.; Bourhaleb, F.; Fausti, F.; Giordanengo, S.; Monaco, V.; Sacchi, R.; Vignati, A.; Cirio, R.; Attili, A.

    2018-04-01

    One major rationale for the application of heavy ion beams in tumour therapy is their increased relative biological effectiveness (RBE). The complex dependencies of the RBE on dose, biological endpoint, position in the field etc require the use of biophysical models in treatment planning and clinical analysis. This study aims to introduce a new software, named ‘Survival’, to facilitate the radiobiological computations needed in ion therapy. The simulation toolkit was written in C++ and it was developed with a modular architecture in order to easily incorporate different radiobiological models. The following models were successfully implemented: the local effect model (LEM, version I, II and III) and variants of the microdosimetric-kinetic model (MKM). Different numerical evaluation approaches were also implemented: Monte Carlo (MC) numerical methods and a set of faster analytical approximations. Among the possible applications, the toolkit was used to reproduce the RBE versus LET for different ions (proton, He, C, O, Ne) and different cell lines (CHO, HSG). Intercomparison between different models (LEM and MKM) and computational approaches (MC and fast approximations) were performed. The developed software could represent an important tool for the evaluation of the biological effectiveness of charged particles in ion beam therapy, in particular when coupled with treatment simulations. Its modular architecture facilitates benchmarking and inter-comparison between different models and evaluation approaches. The code is open source (GPL2 license) and available at https://github.com/batuff/Survival.

  5. Arginine vasopressin increases cellular free calcium concentration and adenosine 3',5'-monophosphate production in rat renal papillary collecting tubule cells in culture

    International Nuclear Information System (INIS)

    Ishikawa, S.; Okada, K.; Saito, T.

    1988-01-01

    The role of calcium (Ca) in the cellular action of arginine vasopressin (AVP) was examined in rat renal papillary collecting tubule cells in culture. AVP increased both the cellular free Ca concentration ([Ca2+]i) using fura-2, and cAMP production in a dose-dependent manner. AVP-induced cellular Ca mobilization was totally blocked by the antagonist to the antidiuretic action of AVP, and somewhat weakened by the antagonist to the vascular action of AVP. 1-Deamino-8-D-AVP (dDAVP). an antidiuretic analog of AVP, also increased [Ca2+] significantly. Cellular Ca mobilization was not obtained with cAMP, forskolin (a diterpene activator of adenylate cyclase), or phorbol-12-myristate-13-acetate. The early phase of [Ca2+]i depended on the intracellular Ca pool, since an AVP-induced rise in [Ca2+]i was obtained in cells pretreated with Ca-free medium containing 1 mM EGTA, verapamil, or cobalt, which blocked cellular Ca uptake. Also, AVP increased 45 Ca2+ influx during the initial 10 min, which initiated the sustained phase of cellular Ca mobilization. However, cellular cAMP production induced by AVP during the 10-min observation period was diminished in the cells pretreated with Ca-free medium, verapamil, or cobalt, but was still significantly higher than the basal level. This was also diminished by a high Ca concentration in medium. These results indicate that 1) AVP concomitantly regulates cellular free Ca as well as its second messenger cAMP production; 2) AVP-induced elevation of cellular free Ca is dependent on both the cellular Ca pool and extracellular Ca; and 3) there is an optimal level of extracellular Ca to modulate the AVP action in renal papillary collecting tubule cells

  6. Literature study of the radiobiological parameters of Caesium-137 required for evaluating internal irradiation doses as a function of age

    International Nuclear Information System (INIS)

    Garnier, A.

    1968-01-01

    This document reassembles information published in scientific literature on radiobiological parameters of Cs-137, necessary for the estimate of the internal irradiation dose of man according to his age (during growth). The data are completed by a commented review of the mathematical models, proposed in order to value the irradiation doses from ingested cesium and the biological parameters. (author) [fr

  7. Radiobiological considerations in gynaecological HDR and LDR brachytherapy

    International Nuclear Information System (INIS)

    Bauer, M.; Schulz-Wendtland, R.

    1989-01-01

    In brachytherapy the advantages of high dose rate over low dose rate afterloading therapy were obvious. Out-patient treatment becomes possible, the position of the sources is reproducible and can be observed during the treatment and the patients have to be immobilised for only a short time, giving less psychological stress and a decreased risk of thrombosis and embolism. When changing from LDR to HDR afterloading therapy we are not yet able to evaluate its biological impact. Radiobiological considerations and our experimental data, however, give us the following clinical consequences by using HDR brachytherapy: There is a need for about 15 fractions or more and each increase in dose rate requires higher fractioning. Due to the steep dose rate decline and the inhomogeneous dose distribution, multiple equivalence factors are necessary when fractioning is not sufficiently high. Correction factors to reduce the dose close to the source are low, with increasing distance from the source they increase. If HDR radiation therapy is used, the percutaneous dose in the pelvic wall region should be reduced. The reduction of the dose in HDR brachytherapy is a compromise to limit the side effects caused by the radiation. The drawback is a small therapeutic range and reduced therapeutic effectivity at the tumour. (orig.) [de

  8. A study of the radiobiological modeling of the conformal radiation therapy in cancer treatment

    Science.gov (United States)

    Pyakuryal, Anil Prasad

    Cancer is one of the leading causes of mortalities in the world. The precise diagnosis of the disease helps the patients to select the appropriate modality of the treatments such as surgery, chemotherapy and radiation therapy. The physics of X-radiation and the advanced imaging technologies such as positron emission tomography (PET) and computed tomography (CT) plays an important role in the efficient diagnosis and therapeutic treatments in cancer. However, the accuracy of the measurements of the metabolic target volumes (MTVs) in the PET/CT dual-imaging modality is always limited. Similarly the external beam radiation therapy (XRT) such as 3D conformal radiotherapy (3DCRT) and intensity modulated radiation therapy (IMRT) is the most common modality in the radiotherapy treatment. These treatments are simulated and evaluated using the XRT plans and the standard methodologies in the commercial planning system. However, the normal organs are always susceptible to the radiation toxicity in these treatments due to lack of knowledge of the appropriate radiobiological models to estimate the clinical outcomes. We explored several methodologies to estimate MTVs by reviewing various techniques of the target volume delineation using the static phantoms in the PET scans. The review suggests that the more precise and practical method of delineating PET MTV should be an intermediate volume between the volume coverage for the standardized uptake value (SUV; 2.5) of glucose and the 50% (40%) threshold of the maximum SUV for the smaller (larger) volume delineations in the radiotherapy applications. Similarly various types of optimal XRT plans were designed using the CT and PET/CT scans for the treatment of various types of cancer patients. The qualities of these plans were assessed using the universal plan-indices. The dose-volume criteria were also examined in the targets and organs by analyzing the conventional dose-volume histograms (DVHs). The biological models such as tumor

  9. Abstracts of the 10. Annual meeting of the Federation of the Experimental Biological Societies; Resumos da 10. Reuniao anual da Federacao de Sociedades de Biologia Experimental

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-12-31

    The meeting was about experimental biology and it was discussed topics related to medicine, pharmacology, cellular biology, biophysics, toxicology, physiology, immunology, radiobiology, photobiology, natural products and environment.

  10. Abstracts of the 10. Annual meeting of the Federation of the Experimental Biological Societies

    International Nuclear Information System (INIS)

    1995-01-01

    The meeting was about experimental biology and it was discussed topics related to medicine, pharmacology, cellular biology, biophysics, toxicology, physiology, immunology, radiobiology, photobiology, natural products and environment

  11. 2. International conference. Radiobiological consequences of nuclear accidents; Russian-Norwegian Satellite Symposium on nuclear accidents, radioecology and health. Abstracts. Part 2

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1994-12-31

    Materials on radiobiological effect of ionizing radiation under emergency situations are presented. The radiation contamination of environmental media after the Chernobyl NPP accident (ground, earth and water ecological systems), effect of external and internal irradiation on the inhabitants of the region are estimated. Time characteristic of radiation risk of originating tumors and genetic injuries is given.

  12. 2. International conference. Radiobiological consequences of nuclear accidents; Russian-Norwegian Satellite Symposium on nuclear accidents, radioecology and health. Abstracts. Part 2

    International Nuclear Information System (INIS)

    1994-01-01

    Materials on radiobiological effect of ionizing radiation under emergency situations are presented. The radiation contamination of environmental media after the Chernobyl NPP accident (ground, earth and water ecological systems), effect of external and internal irradiation on the inhabitants of the region are estimated. Time characteristic of radiation risk of originating tumors and genetic injuries is given

  13. Action spectra in mammalian cells exposed to ultraviolet radiation

    International Nuclear Information System (INIS)

    Anon.

    1981-01-01

    A review is given of the literature published since 1977 on action spectra in mammalian cells exposed to ultraviolet radiation in the wavelength region above 220 nm. Action spectra for lethal events are discussed for cell inactivation in normal cells, growth arrested cells and photosensitive cells. Action spectra for non-lethal events are also discussed in relation to pyrimidine dimer formation, photoreactivation and the use of photosensitisers. It was concluded from these studies that damage to the DNA, and the extent of the repair of this damage, seems to determine a cell's response to such parameters as inactivation, mutation, transformation, latent viral activation, cellular viral capacity and ultraviolet enhanced viral reactivation. In addition to the direct effects of UV on DNA, photosensitization of cellular responses with chemicals such as 8-MOP extend the wavelength range at which damage can be demonstrated. (U.K.)

  14. Amchitka Radiobiological Program progress report, January 1979-December 1979

    International Nuclear Information System (INIS)

    Thornberg, L.D.; Sibley, T.H.; Nakatani, R.E.

    1980-07-01

    The objective of the Amchitka Radiobiological Program for the period 1970-1979 was to determine the extent of radionuclide contamination from world-wide atmospheric fallout and from the detonation of three underground nuclear blasts on Amchitka Island. The objective is achieved, by the collection and radiological analyses of biological and environmental samples and by background radiation measurements. Leakage of radionuclides from the underground sites of the Amchitka nuclear detonations would be suspected if the contamination was significntly greater than would be expected from world fallout. An account of the program from July 1970 to December 1978 has been given in nine previous reports from the Laboratory of Radiation Ecology to the Nevada Operations Office of the US Department of Energy. This report is an account of the program for calendar year 1979. The results of analyses of the samples collected in 1979 lead to the same conclusions as in previous years; i.e., there is no evidence that the radionuclide contamination at Amchitka Island is greater than would be expected from world fallout except for a slight contamination of the Long Shot Mud Pits with tritium

  15. Hidden stressors in the clonogenic assay used in radiobiology experiments

    International Nuclear Information System (INIS)

    Potter, M.D.E.; Suchowerska, N.; Rizvi, S.; McKenzie, D.R.

    2011-01-01

    Full text: While clonogenic assays are extensively used in radiobiology, there is no widely accepted procedure for choosing the composition of the cell culture media. Cell line suppliers recommend a specific culture medium for each cell line, however a researcher will frequently customize this aspect of the protocol by supplementing the recommended support medium with additives. For example, many researchers add antibiotics, in order to avoid contamination of cells and the consequent loss of data, with little discussion of the influence of the antibiotics on the clonogenic survival of the cells. It is assumed that the effect of any variables in the growth medium on cell survival is taken into consideration by comparing the survival fraction relative to that of controls grown under the same conditions. In the search for better cancer treatment, the effect of various stressors on clonogenic cell survival is under investigation. This study seeks to identify and test potential stressors commonly introduced into the cell culture medium, which may confound the response to radiation. (author)

  16. The molecular basis of radiation action

    International Nuclear Information System (INIS)

    Smith, K.C.

    1985-01-01

    Before turning his full attention to research on oncogenic viruses, Henry S. Kaplan made seminal contributions to the field of molecular radiobiology during the years from 1960 to 1975. One of his first areas of interest in microbial radiobiology was the radiation sensitization of cells by the incorporation into DNA of analogs of the natural purines and pyrimidines. This fundamental work ultimately led to clinical trials using halogenated pyrimidines in conjunction with radiation therapy. Dr Kaplan published the first method for assaying for the formation and repair of DNA double-strand breaks, and made other major contributions to our understanding of the biological importance of X-ray-induced DNA strand breaks, and the modulation of their repair. The specifics of Dr. Kaplan's discoveries in these areas are discussed, as well as some recent work from the author's laboratory that unifies some of the earlier work of Dr. Kaplan on the repair of DNA strand breaks

  17. Development of a tool computer to compensate for interruptions of treatment and radiobiological comparisons Tr in external radiotherapy; Desarrollo de una herramienta informatica para la compensacion de interrupciones de tratamiento y comparaciones radiobiologicas en radioterapia externa

    Energy Technology Data Exchange (ETDEWEB)

    Ramos Pacho, J. A.; Sena Espinel, E.; Verde Velasco, J. M.; Garcia Repiso, S.; Perez Alvarez, M. E.; Delgado Apaaricio, J. M.; Martin Rincon, C.; Saez Beltran, M.; Gomez Gonzalez, N.; Cons Perez, N.

    2013-07-01

    Outages unscheduled in the course of external beam radiation treatments, and the loss of probability of tumour control (TCP), which make it necessary to have a tool that allows the adjustment of the compensation of the absorbed dose required to keep the biological effect on the tumor, controlling the possible impact on the organ at risk. In order to perform this radiobiological quickly setting has been developed a software application that also allows comparison of treatments with different subdivisions from the point of view of radiobiological. (Author)

  18. Modeling of coupled differential equations for cellular chemical signaling pathways: Implications for assay protocols utilized in cellular engineering.

    Science.gov (United States)

    O'Clock, George D

    2016-08-01

    Cellular engineering involves modification and control of cell properties, and requires an understanding of fundamentals and mechanisms of action for cellular derived product development. One of the keys to success in cellular engineering involves the quality and validity of results obtained from cell chemical signaling pathway assays. The accuracy of the assay data cannot be verified or assured if the effect of positive feedback, nonlinearities, and interrelationships between cell chemical signaling pathway elements are not understood, modeled, and simulated. Nonlinearities and positive feedback in the cell chemical signaling pathway can produce significant aberrations in assay data collection. Simulating the pathway can reveal potential instability problems that will affect assay results. A simulation, using an electrical analog for the coupled differential equations representing each segment of the pathway, provides an excellent tool for assay validation purposes. With this approach, voltages represent pathway enzyme concentrations and operational amplifier feedback resistance and input resistance values determine pathway gain and rate constants. The understanding provided by pathway modeling and simulation is strategically important in order to establish experimental controls for assay protocol structure, time frames specified between assays, and assay concentration variation limits; to ensure accuracy and reproducibility of results.

  19. A study of the mechanism of action of pyridoxal isonicotinoyl hydrazone at the cellular level using reticulocytes loaded with non-heme 59Fe

    International Nuclear Information System (INIS)

    Huang, A.R.; Ponka, P.; McGill Univ., Montreal, Quebec; Jewish General Hospital, Montreal, Quebec

    1983-01-01

    Pyridoxal isonicotinoyl hydrazone (PIH) has recently been identified as a new iron chelating agent with a high degree of iron mobilizing activity in vitro and in vivo which makes this compound a candidate drug in the treatment of iron overload. This study was undertaken to elucidate the mechanism of action of the iron mobilizing activity of PIH at the cellular level. An in vitro system of rabbit reticulocytes with a high level of non-heme 59 Fe was used as a model of iron overload. The effects of various biochemical and physiological manoeuvers on the mobilization of 59 Fe by PIH from the cells were studied. The fate of [ 14 C]-PIH in the in vitro system was also studied. Studies were also carried out using a crude mitochondrial fraction. (orig./AJ)

  20. Amchitka Radiobiological Program. Final report, July 1970-December 1979

    International Nuclear Information System (INIS)

    Sibley, T.H.; Tornberg, L.D.

    1982-11-01

    The Amchitka Radiobiological Program, to collect biological and environmental samples for radiological analyses, began in 1970 and continued through 1979. The principal objective was to determine the extent of radionuclide contamination from worldwide atmospheric fallout and from the detonation of three underground nuclear tests on Amchitka. Leakage of radionuclides from the underground test sites would be suspected if the amount of contamination was significantly greater than could be attributed to worldwide fallout or if an unexpected assemblage of radionuclides was detected. No radionuclides from the underground sites were detected, except for tritium from the Long Shot test (1965) which produced increased tritium concentrations in surface water and freshwater plants near the test site. This final report compiles all previous data into one report and considers the temporal trends in these data. Two naturally occurring radionuclides, 40 K and 7 Be, were the most abundantly occurring radionuclides in most samples; in lichen samples either 137 Cs or 144 Ce had the highest activity. All samples were below applicable Radiation Protection Guides and by 1979 most samples were near or below the statistical detection limits. Increased concentrations of short-lived fallout radionuclides following the Chinese atmospheric tests were found in freshwater and seawater samples and in most indicator organisms

  1. Quantum features of natural cellular automata

    International Nuclear Information System (INIS)

    Elze, Hans-Thomas

    2016-01-01

    Cellular automata can show well known features of quantum mechanics, such as a linear rule according to which they evolve and which resembles a discretized version of the Schrödinger equation. This includes corresponding conservation laws. The class of “natural” Hamiltonian cellular automata is based exclusively on integer-valued variables and couplings and their dynamics derives from an Action Principle. They can be mapped reversibly to continuum models by applying Sampling Theory. Thus, “deformed” quantum mechanical models with a finite discreteness scale l are obtained, which for l → 0 reproduce familiar continuum results. We have recently demonstrated that such automata can form “multipartite” systems consistently with the tensor product structures of nonrelativistic many-body quantum mechanics, while interacting and maintaining the linear evolution. Consequently, the Superposition Principle fully applies for such primitive discrete deterministic automata and their composites and can produce the essential quantum effects of interference and entanglement. (paper)

  2. The relationships between radiation doses and their effects

    International Nuclear Information System (INIS)

    Beau, P.G.; Nenot, J.C.

    1982-01-01

    Dose-effect relationships have been developed both for the biological effects studied by Radiobiology and the long-term pathological effects (malignant diseases) studied by Radiation Protection. The former approach chiefly considers the primary biological injuries at the cellular level, and the relationship between the dependent variable characteristic of the effect and the dose -an independent variable- has an explanatory meaning. The parameters associated to the independent variable have a biophysical signification and fit into a model of the action of ionizing radiations. In the latter approach, the relationship is pragmatic and the previous parameters are just the results of a curve-fitting procedure realized on experimental or human data. The biophysical models have led to a general formulation associating a linear term to a quadratic term both of them weighted by an exponential term describing cellular killing at the highest doses. To a certain extent the curves obtained for leukemias, bronchopulmonary and breast cancers prove the validity of the pragmatic model [fr

  3. Dictionary of radiation protection, radiobiology and nuclear medicine. English-German-French-Russian. Strahlenschutz, Strahlenbiologie, Nuklearmedizin. Englisch-Deutsch-Franzoesisch-Russisch

    Energy Technology Data Exchange (ETDEWEB)

    Sube, R

    1985-01-01

    This multilingual dictionary covers the subject fields of radiation protection, radiobiology, and nuclear medicine with about 12,000 terms in each language. All terms are supplemented by one or more abbreviations of 22 special branches to assure the use of the very relevant terms. Special branches listed are for instance decontamination, dosimetry, atomic legislation, radiation detectors, radiography (medical), radiotherapy, safeguards, shielding, tansportation and storage. The terminology used in the International Nuclear Information System (INIS) of the IAEA has been completely taken into account.

  4. Track structure and dose: Alternative conceptual bases for nuclear therapy

    International Nuclear Information System (INIS)

    Katz, R.

    1987-01-01

    As one departs from the island of radiation quality encompassing photons and electrons of initial energy from about 100 keV to about 10 MeV toward increasingly higher LET particle irradiations, and from relatively uniform to inherently non-uniform radiation fields, dose and LET become less useful indices of radiation effect. Isodose profiles are not isoeffect profiles. RBEs vary with end point, with the state of oxygenation, with cell line, with tissue identity and with dose, and are multiple valued functions of LET. Dose, microdose and LET lack the descrimination needed to predict biological end points. RBE calculations made from cellular radiosensitivity parameters are consistent with RBEs measured both in vitro and in vivo. For such calculations, we must know the spectrum of particles and particle energies making up a high LET radiation field. To sharpen the calculations and make them directly relevant to therapy, we need to evaluate radiosensitivity parameters for human tissues. Both physical and biological data are needed for radiobiology and radiotherapy. For the question of hazard evaluation, we need to know the relation between transformations in vitro and cancer production in vivo. Using the same model as was used earlier for cellular inactivations, we have fitted tentative radiosensitivity parameters to recent data for cell transformations. The model is consistent with both gamma ray and fission neutron measurements. But a wider range of irradiations is needed to test these results. Delta rays play an important role in heavy ion radiobiology, but we do not now know either the cross-sections for delta ray production or the radial deposition of their energy with sufficient precision or generality. But it is this, the radial dose deposition, which is the physical basis for the calculation of action cross-sections. Studies for radiobiology and radiotherapy should also include the response of different physical detectors to a range of radiations, especially

  5. 76 FR 82179 - Drivers of CMVs: Restricting the Use of Cellular Phones

    Science.gov (United States)

    2011-12-30

    ... DEPARTMENT OF TRANSPORTATION Federal Motor Carrier Safety Administration 49 CFR Part 390 Drivers of CMVs: Restricting the Use of Cellular Phones AGENCY: Federal Motor Carrier Safety Administration (FMCSA), DOT. ACTION: Final rule; correction. SUMMARY: FMCSA is correcting a Final Rule that appeared in...

  6. Radiobiological aspects of application of interleucine as agents for the first aid under strong radiation action

    International Nuclear Information System (INIS)

    Rozhdestvensij, L.M.

    1997-01-01

    The paper substantiates the application of the interleucine-1 beta (IL-1) as an emergency medical care agent in case of the acute emergency exposure of a human being. During simulation experiments a human recombinant IL-1 was added to suspension of the affected bony marrow-cells extracted a few minutes following the total 5 Gy exposure of Fi male-mice (CBAxC57B1). Recombinant mouse IL-3 and GM-CSF agents (produced by Bering company, Germany) were used for comparison purpose (agent concentration constituted 100-10000 unit/ml). The incubated bony marrow cells were tested for trunk potencies in mice-recipients irradiated by 8.5 Gy dose during 24 h. Following nine days the colonies in their spleen and bony marrow cellular texture were estimated. IL-1 was shown to have the protective effect both on separated trunk type hemopoietic cells and on the whole body irradiated hemopoietic system. IL-1 turned to be similar to radiation-protective agents of polysaccharide nature and to radiation-protective EIR procedure. It is pointed out that IL-1 has no whole body toxic or any other by effects [ru

  7. Skin, eye, and testis: current exposure problems and recent advances in radiobiology

    International Nuclear Information System (INIS)

    Charles, M.W.

    1986-01-01

    Three organs, the skin, eye and testis are potentially at risk from poorly penetrating radiations such as beta particles or low energy X-Rays. They may be preferentially irradiated in fields with steep depth - dose gradients and thereby dictate radiological protection procedures. Since there is not a wide margin of safety in the annual permissible dose limits for these organs it is important to have clearly defensible methods of dose assessment. This requires both an adequate understanding of the radiobiology of these organs and the availability of experimental techniques for measuring doses at various depths near the surface of the body. This paper reviews the current state of knowledge in this field, drawing partly on information from two recent CEC workshops on the 'Dosimetry of Beta Particles and Low Energy X-Rays' and 'Radiation Damage to the Skin'. It is concluded that protection criteria for the limitation of skin dose are in need of revision. (author)

  8. An in vitro study of the radiobiological effects of flattening filter free radiotherapy treatments

    International Nuclear Information System (INIS)

    King, R B; Hyland, W B; McGarry, C K; Hounsell, A R; Cole, A J; Butterworth, K T; McMahon, S J; Redmond, K M; Trainer, C; Prise, K M

    2013-01-01

    Flattening filter free (FFF) linear accelerators allow for an increase in instantaneous dose-rate of the x-ray pulses by a factor of 2–6 over the conventional flattened output. As a result, radiobiological investigations are being carried out to determine the effect of these higher dose-rates on cell response. The studies reported thus far have presented conflicting results, highlighting the need for further investigation. To determine the radiobiological impact of the increased dose-rates from FFF exposures a Varian Truebeam medical linear accelerator was used to irradiate two human cancer cell lines in vitro, DU-145 prostate and H460 non-small cell lung, with both flattened and FFF 6 MV beams. The fluence profile of the FFF beam was modified using a custom-designed Nylon compensator to produce a similar dose profile to the flattened beam (6X) at the cell surface but at a higher instantaneous dose-rate. For both cell lines there appeared to be no significant change in cell survival. Curve fitting coefficients for DU145 cells irradiated with constant average dose-rates were 6X: α = 0.09 ± 0.03, β = 0.03 ± 0.01 and 6FFF: α = 0.14 ± 0.13, β = 0.03 ± 0.02 with a significance of p = 0.75. For H460 cells irradiated with the same instantaneous dose-rate but different average dose-rate the fit coefficients were 6FFF (low dose-rate): α = 0.21 ± 0.11, 0.07 ± 0.02 and 6FFF (high dose-rate): α = 0.21 ± 0.16, 0.07 ± 0.03, with p = 0.79. The results indicate that collective damage behaviour does not occur at the instantaneous dose-rates investigated here and that the use of either modality should result in the same clinical outcome, however this will require further validation in vivo. (note)

  9. Targeting the epidermal growth factor receptor in radiotherapy: radiobiological mechanisms, preclinical and clinical results

    International Nuclear Information System (INIS)

    Baumann, Michael; Krause, Mechthild

    2004-01-01

    Background and purpose: Inhibition of the epidermal growth factor receptor (EGFR) is a fastly developing field in preclinical and clinical cancer research. This review presents the current status of knowledge and discusses radiobiological mechanisms which may underly the efficacy of EGFR inhibitors combined with irradiation. Materials and methods: Preclinical and clinical results on combined targeting of the EGFR and irradiation from the literature and from this laboratory are reviewed. Focus is given to the radiobiological rationale of this approach and to endpoints of experimental radiotherapy. Results: Overexpression of the EGFR is associated with decreased local tumour control after radiotherapy, especially when the overall treatment time is long. Inhibition of the EGFR either alone or in combination with irradiation decreases the growth rate of tumours expressing this receptor. Preclinical data provide proof-of-principle that local tumour control may be improved by combining irradiation with C225 mAb. In a randomised phase III clinical trial, simultaneous irradiation and treatment with the EGFR antibody Cetuximab (Erbitux[reg]; C225) in head and neck cancer patients resulted in significantly improved locoregional tumour control and survival compared to curative irradiation alone. Acute skin reactions increased in the experimental arm. The underlying mechanisms of enhanced radiation effects of combined EGFR inhibition with irradiation and of the partly conflicting results in different studies are poorly understood. There is increasing evidence, that important intertumoral heterogeneity in the response to EGFR inhibition alone and combined with irradiation exists, which appears to be at least partly dependent on specific mutations of the receptor as well as of molecules that are involved in the intracellular signal transduction pathway. Conclusions and outlook: Further investigations at all levels of the translational research chain exploring the mechanisms of

  10. Mechanisms underlying prorenin actions on hypothalamic neurons implicated in cardiometabolic control

    Directory of Open Access Journals (Sweden)

    Soledad Pitra

    2016-10-01

    Conclusions: We identified novel neuronal targets and cellular mechanisms underlying PR/PRR actions in critical hypothalamic neurons involved in cardiometabolic regulation. This fundamental mechanistic information regarding central PR/PRR actions is essential for the development of novel RAS-based therapeutic targets for the treatment of cardiometabolic disorders in obesity and hypertension.

  11. Introduction to radiation biology

    International Nuclear Information System (INIS)

    Uma Devi, P.; Satish Rao, B.S.; Nagarathnam, A.

    2000-01-01

    This book is arranged in a logical sequence, starting from radiation physics and radiation chemistry, followed by molecular, subcellular and cellular effects and going on to the level of organism. Topics covered include applied radiobiology like modifiers of radiosensitivity, predictive assay, health physics, human genetics and radiopharmaceuticals. The topics covered are : 1. Radiation Physics, 2. Detection and Measurement of Radiation, 3. Radiation Chemistry, 4. DNA Damage and Repair, 5. Chromosomal Aberrations and Gene Mutations, 6. Cellular Radiobiology 7. Acute Radiation Effects, 8. Delayed Effects of Radiation, 9. Biological Basis of Radiotherapy, 10. Chemical Modifiers of Radiosensitivity, 11. Hyperthermia, 12. High LET Radiations in Cancer, Therapy, 13. Predictive Assays, 14. Radiation Effects on Embryos, 15. Human Radiation Genetics, 16. Radiolabelled Compounds in Biology and Medicine and 17. Radiological Health

  12. Effects of radiographic contrast media on cellular electrophysiology in the beating heart

    Energy Technology Data Exchange (ETDEWEB)

    Wolpers, H.G.; Baller, D.; Ensink, F.B.M.; Hoeft, A.; Korb, H.; Hellige, G.

    1982-01-01

    Electrophysiological effects of intracoronarily administered contrast media have been documented in 12 thoracotomized dogs at the cellular level by use of a modified microelectrode technique. Injections (n = 63) of 4 different contrast media uniformly led to a temporary cellular hyperpolarisation of the resting potential and prolongation of the action potential. Additional experiments with intracoronary injections of several electrolyte concentrations, mainly by a local deficiency of potassium ions and an excess of sodium ions. The significance of the findings for mechanisms underlying ECG-changes and ventricular arrhythmia by radiographic contrasts media will be discussed.

  13. Radiobiology in clinical radiation therapy part I - Systems and principles

    International Nuclear Information System (INIS)

    Hall, Eric J.

    1996-01-01

    Objective: This course is designed for residents in radiation oncology, preparing for their boards. It includes the physics and chemistry of the absorption of radiation, a description of the biological systems used to obtain a quantitative relationship between dose and biological effect, as well as a review of the basic principles in radiation biology that have been established. The biological effects of radiation may result from the direct action, which refers to ionizations in the DNA itself, or the indirect action which is mediated by free radicals. For x or gamma rays, about 70% of the damage is by the indirect action, which can be modified by oxygen and various chemical agents. Radiation-induced DNA damage may lead to carcinogenesis and hereditary effects, which are important in personnel protection, or to cell lethality which is the basis of radiotherapy. Chromosome aberrations and cell lethality appear to result from the interaction of two lesions (probably double strand breaks) which leads to the linear-quadratic relationship. This refers to mitotic death, which is the most common form of radiation induced death. Programmed cell death orApoptosis also occurs which appears to be important in more radiosensitive tumors, and relatively unimportant in radioresistant tumors. A number of quantitative biological test systems have been developed to quantify the effects of radiation as a function of dose. Cells may be cultured in vitro, of normal and neoplastic origin, and survival curves produced with reproductive integrity plotted as a function of dose. Normal tissue systems where reproductive integrity can be scored as an endpoint include skin, gut, colony forming units in the bone marrow, as well as breast, thyroid and testis. The response of some normal tissues depends, not only on the fraction of cells killed, but on the tissue architecture in terms of functional subunits, this will be discussed in Part III. A range of transplantable tumors have been studied

  14. Radiation biology of medical imaging

    CERN Document Server

    Kelsey, Charles A; Sandoval, Daniel J; Chambers, Gregory D; Adolphi, Natalie L; Paffett, Kimberly S

    2014-01-01

    This book provides a thorough yet concise introduction to quantitative radiobiology and radiation physics, particularly the practical and medical application. Beginning with a discussion of the basic science of radiobiology, the book explains the fast processes that initiate damage in irradiated tissue and the kinetic patterns in which such damage is expressed at the cellular level. The final section is presented in a highly practical handbook style and offers application-based discussions in radiation oncology, fractionated radiotherapy, and protracted radiation among others. The text is also supplemented by a Web site.

  15. The effect of ionizing radiation with different ionizing density on the uni-cellular Alga Micrasterias denticulate Breb

    International Nuclear Information System (INIS)

    Reubel, B.

    1982-01-01

    The uni-cellular green alga Micrasterias denticulata Breb is very suitable for cytological, ultrastructural investigations as well as for growth studies of cell populations because of its size and its specific cellular pattern. Therefore these cells were investigated for their cell-cycle-dependent reaction to different types of radiation, dose-rates and cumulated doses and compared with results from the literature on radiobiological effects on single cells. Different types of ionizing radiation were used such as gamma rays ( 60 Co, 241 Am), alpha rays ( 241 Am) neutrons ( 252 Cf and 14 MeV-neutrons from a particle-accelerator) and protons (20-MeV-protons from a particle-accelerator). Irradiation with low doses (gamma-, neutron irradiation) did not show any statistically significant results. No effects could be observed after alpha irradiation because of the alpha particles could not penetrate the mucus cover. Irradiation with gamma rays and protons showed statistically significant reversible and irreversible effects. The reversible effect appeared in a dose-dependent division-delay of the populations. The results from literature, cell-cycle observations and ultra-structural investigations point to a block in the G 2 -phase and prolongation of the S-phase. Irreversible irradiation damage is caused by neutron- and proton irradiation. In the first case the length of division delay shows no dose-dependence. In the second case the following cell-cycles are retarded. The dose-effect-curves of proton-irradiations with different dose-rates show a plateau at high doses, which seems to be effected by the turn-on of an additional repair-mechanism. (Author)

  16. The anticonvulsant action of the galanin receptor agonist NAX-5055 involves modulation of both excitatory- and inhibitory neurotransmission

    DEFF Research Database (Denmark)

    Walls, Anne B; Flynn, Sean P; West, Peter J

    2016-01-01

    -based anti-convulsant drugs was prompted. Based on this, a rationally designed GalR1 preferring galanin analogue, NAX-5055, was synthesized. This compound demonstrates anti-convulsant actions in several animal models of epilepsy. However, the alterations at the cellular level leading to this anti......-convulsant action of NAX-5055 are not known. Here we investigate the action of NAX-5055 at the cellular level by determining its effects on excitatory and inhibitory neurotransmission, i.e. vesicular release of glutamate and GABA, respectively, in cerebellar, neocortical and hippocampal preparations. In addition...

  17. Two distinct and competitive pathways confer the cellcidal actions of artemisinins

    Directory of Open Access Journals (Sweden)

    Chen Sun

    2015-01-01

    Full Text Available The biological actions of artemisinin (ART, an antimalarial drug derived from Artemisia annua, remain poorly understood and controversial. Besides potent antimalarial activity, some of artemisinin derivatives (together with artemisinin, hereafter referred to as ARTs, in particular dihydroartemisinin (DHA, are also associated with anticancer and other antiparasitic activities. In this study, we used baker’s yeast Saccharomyces cerevisiae as cellular and genetic model to investigate the molecular and cellular properties of ARTs. Two clearly separable pathways exist. While all ARTs exhibit potent anti-mitochondrial actions as shown before, DHA exerts an additional strong heme-dependent, likely mitochondria-independent inhibitory action. More importantly, heme antagonizes the mitochondria-dependent cellcidal action. Indeed, when heme synthesis was inhibited, the mitochondria-dependent cellcidal action of ARTs could be dramatically strengthened, and significant yeast growth inhibition at as low as 100 nM ART, an increase of about 25 folds in sensitivity, was observed. We conclude that ARTs are endowed with two major and distinct types of properties: a potent and specific mitochondria-dependent reaction and a more general and less specific heme-mediated reaction. The competitive nature of these two actions could be explained by their shared source of the consumable ARTs, so that inhibition of the heme-mediated degradation pathway would enable more ARTs to be available for the mitochondrial action. These properties of ARTs can be used to interpret the divergent antimalarial and anticancer actions of ARTs.

  18. Sub-cellular distribution and translocation of TRP channels.

    Science.gov (United States)

    Toro, Carlos A; Arias, Luis A; Brauchi, Sebastian

    2011-01-01

    Cellular electrical activity is the result of a highly complex processes that involve the activation of ion channel proteins. Ion channels make pores on cell membranes that rapidly transit between conductive and non-conductive states, allowing different ions to flow down their electrochemical gradients across cell membranes. In the case of neuronal cells, ion channel activity orchestrates action potentials traveling through axons, enabling electrical communication between cells in distant parts of the body. Somatic sensation -our ability to feel touch, temperature and noxious stimuli- require ion channels able to sense and respond to our peripheral environment. Sensory integration involves the summing of various environmental cues and their conversion into electrical signals. Members of the Transient Receptor Potential (TRP) family of ion channels have emerged as important mediators of both cellular sensing and sensory integration. The regulation of the spatial and temporal distribution of membrane receptors is recognized as an important mechanism for controlling the magnitude of the cellular response and the time scale on which cellular signaling occurs. Several studies have shown that this mechanism is also used by TRP channels to modulate cellular response and ultimately fulfill their physiological function as sensors. However, the inner-working of this mode of control for TRP channels remains poorly understood. The question of whether TRPs intrinsically regulate their own vesicular trafficking or weather the dynamic regulation of TRP channel residence on the cell surface is caused by extrinsic changes in the rates of vesicle insertion or retrieval remain open. This review will examine the evidence that sub-cellular redistribution of TRP channels plays an important role in regulating their activity and explore the mechanisms that control the trafficking of vesicles containing TRP channels.

  19. Relationship between radiobiological hypoxia in a C3H mouse mammary carcinoma and osteopontin levels in mouse serum

    DEFF Research Database (Denmark)

    Lukácová, Slávka; Khalil, Azza Ahmed; Overgaard, Jens

    2005-01-01

    To investigate the possible relationship between radiobiological hypoxia in a C3H mouse mammary carcinoma and osteopontin (OPN) levels measured in mouse serum. MATERIAL AND METHODS: Experiments were performed in CDF1 mice that were either non-tumour bearing or with different sized tumours implanted...... in the right rear foot. Osteopontin levels in extracted mouse blood serum and tissue from the transplanted tumours were measured using an ELISA assay. The tumour oxygenation status was estimated using the Eppendorf Histograph and the fraction of oxygen partial pressure (pO2) values =5 mm Hg (HF5...

  20. The effect of cellular aging on the dynamics of spiral waves

    International Nuclear Information System (INIS)

    Deng Min-Yi; Chen Xi-Qiong; Tang Guo-Ning

    2014-01-01

    Cellular aging can result in deterioration of electrical coupling, the extension of the action potential duration, and lower excitability of the cell. Those factors are introduced into the Greenberg—Hastings cellular automaton model and the effects of the cellular aging on the dynamics of spiral waves are studied. The numerical results show that a 50% reduction of the coupling strength of aging cells has a little influence on spiral waves. If the coupling strength of aging cells equals zero, the ability for the medium to maintain spiral waves will be reduced by approximately 50% when the aging cell ratio increases from 0 to 0.5, where the reduction of cell excitability plays a major role in inducing disappearance of spiral waves. When the relevant parameters are properly chosen, the cellular aging can lead to the meandering of spiral waves, the emergence of the binary spiral waves, and even the disappearance of spiral waves via the stopping rotation or shrinkage of wave. Physical mechanisms of the above phenomena are analyzed briefly. (general)

  1. Tail's Entropy and dose of critical annihilation: a new view of the problem radiobiological; Entropia de Tsallis y dosis de aniquilacion critica: una nueva vision del problema radiobiologico

    Energy Technology Data Exchange (ETDEWEB)

    Sotolongo Grau, O.; Rodriguez Perez, D.; Antoranz, J. C.

    2011-07-01

    The aim of this paper is to present a model based on a minimum radiobiological physical hypotheses containing known models as special cases, allowing to define operations of addition and multiplication dose survival probabilities to fit the experimental data.

  2. Light ion production for a future radiobiological facility at CERN: preliminary studies.

    Science.gov (United States)

    Stafford-Haworth, Joshua; Bellodi, Giulia; Küchler, Detlef; Lombardi, Alessandra; Röhrich, Jörg; Scrivens, Richard

    2014-02-01

    Recent medical applications of ions such as carbon and helium have proved extremely effective for the treatment of human patients. However, before now a comprehensive study of the effects of different light ions on organic targets has not been completed. There is a strong desire for a dedicated facility which can produce ions in the range of protons to neon in order to perform this study. This paper will present the proposal and preliminary investigations into the production of light ions, and the development of a radiobiological research facility at CERN. The aims of this project will be presented along with the modifications required to the existing linear accelerator (Linac3), and the foreseen facility, including the requirements for an ion source in terms of some of the specification parameters and the flexibility of operation for different ion types. Preliminary results from beam transport simulations will be presented, in addition to some planned tests required to produce some of the required light ions (lithium, boron) to be conducted in collaboration with the Helmholtz-Zentrum für Materialien und Energie, Berlin.

  3. Transformation of Physical DVHs to Radiobiologically Equivalent Ones in Hypofractionated Radiotherapy Analyzing Dosimetric and Clinical Parameters: A Practical Approach for Routine Clinical Practice in Radiation Oncology

    Directory of Open Access Journals (Sweden)

    Zoi Thrapsanioti

    2013-01-01

    Full Text Available Purpose. The purpose of this study was to transform DVHs from physical to radiobiological ones as well as to evaluate their reliability by correlations of dosimetric and clinical parameters for 50 patients with prostate cancer and 50 patients with breast cancer, who were submitted to Hypofractionated Radiotherapy. Methods and Materials. To achieve this transformation, we used both the linear-quadratic model (LQ model and the Niemierko model. The outcome of radiobiological DVHs was correlated with acute toxicity score according to EORTC/RTOG criteria. Results. Concerning the prostate radiotherapy, there was a significant correlation between RTOG acute rectal toxicity and ( and ( dosimetric parameters, calculated for  Gy. Moreover, concerning the breast radiotherapy there was a significant correlation between RTOG skin toxicity and dosimetric parameter, calculated for both  Gy ( and  Gy (. The new tool seems reliable and user-friendly. Conclusions. Our proposed model seems user-friendly. Its reliability in terms of agreement with the presented acute radiation induced toxicity was satisfactory. However, more patients are needed to extract safe conclusions.

  4. Biological Effects of Neutron and Proton Irradiations. Vol. II. Proceedings of the Symposium on Biological Effects of Neutron Irradiations

    International Nuclear Information System (INIS)

    1964-01-01

    During recent years the interest in biological effects caused by neutrons has been increasing steadily as a result of the rapid development of neutron technology and the great number of neutron sources being used. Neutrons, because of their specific physical characteristics and biological effects, form a special type of radiation hazard but, at the same time, are a prospective tool for applied radiobiology. This Symposium, held in Brookhaven at the invitation of the United States Government from 7-11 October 1963, provided an opportunity for scientists to discuss the experimental information at present available on the biological action of neutrons and to evaluate future possibilities. It was a sequel to the Symposium on Neutron Detection, Dosimetry and Standardization, which was organized by the International Atomic Energy Agency in December 1962 at Harwell. The Symposium was attended by 128 participants from 17 countries and 6 international organizations. Fifty-four papers were presented. The following subjects were discussed in various sessions: (1) Dosimetry. Estimation of absorbed dose of neutrons in biological material. (2) Biological effects of high-energy protons. (3) Cellular and genetic effects. (4) Pathology of neutron irradiation, including acute and chronic radiation syndromes (mortality, anatomical and histological changes, biochemical and metabolic disturbances) and delayed consequences. (5) Relative biological effectiveness of neutrons evaluated by different biological tests. A Panel on Biophysical Considerations in Neutron Experimentation, with special emphasis on informal discussions, was organized during the Symposium. The views of the Panel are recorded in Volume II of the Proceedings. Many reports were presented on the important subject of the relative effectiveness of the biological action of neutrons, as well as on the general pathology of neutron irradiation and the cellular and genetic effects related to it. Three survey papers considered

  5. Modeling volume effects of experimental brachytherapy in the rat rectum: uncovering the limitations of a radiobiologic concept

    International Nuclear Information System (INIS)

    Johannessen, Hans-Olaf; Dale, Einar; Hellebust, Taran P.; Olsen, Dag R.; Nesland, Jahn M.; Giercksky, Karl-Erik

    2002-01-01

    Purpose: To analyze the significance of volume effects in experimental brachytherapy, based on modeling normal tissue complication probability. Methods and Materials: Experimental brachytherapy in the rat rectum was based on an eight-step 2.5-mm step size source configuration for 192 Ir, afterloaded into an unshielded polystyrene applicator. Volume effects were studied using a half-circumferential lead-shielded applicator and a shorter (two-step) source configuration. The main end point was rectal stenosis. Results: Rectal stenosis was always caused by a radiation ulcer. With the shielded configuration, single-dose ED 50 (50% incidence of rectal stenosis) increased from 23 Gy to 36.5 Gy. Single-dose ED 50 for the short configuration was 77.9 Gy. The data showed a reasonable fit to a three-parameter version of the biophysical model described by Jackson et al. (1995). This model assumes that organs consist of a large number of radiobiologically independent subunits and that radiation causes a complication if the fraction of the organ damaged is greater than its functional reserve. The fraction of the organ damaged is calculated summing over fractions of the organ damaged at each dose level. The calculated mean functional reserve (ν 50 ) of the rat rectum, assuming a cumulative functional reserve distribution in the group of experimental rats, was 0.53. Conclusions: The volume effect observed within small brachytherapy volumes agreed well with clinical experience of large tolerance doses in contact X-ray therapy. However, the ν 50 value was comparable to the high functional reserve value reported for liver. Experimental volume effects probably reflect repair processes originating in the areas adjacent to small radiation fields of brachytherapy more than the radiobiologic characteristics of the cells in the irradiated volume

  6. Cellular dynamics of bovine aortic smooth muscle cells measured using MEMS force sensors

    Science.gov (United States)

    Tsukagoshi, Takuya; Nguyen, Thanh-Vinh; Hirayama Shoji, Kayoko; Takahashi, Hidetoshi; Matsumoto, Kiyoshi; Shimoyama, Isao

    2018-04-01

    Adhesive cells perceive the mechanical properties of the substrates to which they adhere, adjusting their cellular mechanical forces according to their biological characteristics. This mechanical interaction subsequently affects the growth, locomotion, and differentiation of the cell. However, little is known about the detailed mechanism that underlies this interaction between adherent cells and substrates because dynamically measuring mechanical phenomena is difficult. Here, we utilize microelectromechamical systems force sensors that can measure cellular traction forces with high temporal resolution (~2.5 µs) over long periods (~3 h). We found that the cellular dynamics reflected physical phenomena with time scales from milliseconds to hours, which contradicts the idea that cellular motion is slow. A single focal adhesion (FA) generates an average force of 7 nN, which disappears in ms via the action of trypsin-ethylenediaminetetraacetic acid. The force-changing rate obtained from our measurements suggests that the time required for an FA to decompose was nearly proportional to the force acting on the FA.

  7. Evaluation of the radiobiological impact of anatomic modifications during radiation therapy for head and neck cancer: Can we simply summate the dose?

    International Nuclear Information System (INIS)

    Orban de Xivry, Jonathan; Castadot, Pierre; Janssens, Guillaume; Lee, John Aldo; Geets, Xavier; Gregoire, Vincent; Macq, Benoit

    2010-01-01

    Background and purpose: Adaptive strategies in radiotherapy (RT) require the knowledge of the total dose given to every organ of the body. Because of anatomical changes and setup errors non-rigid registration is necessary to map the different dose fractions to a common reference. This study evaluates practically if the accumulation of all of these registered dose fractions must take radiobiology into account in a classical clinical setting. Materials and methods: Ten patients with head and neck tumors treated by chemo-RT were used. Contrast-enhanced CT scans were acquired prior and during RT following delivery of mean doses of 14.2, 24.5, 35.0 and 44.9 Gy and the planned pre-treatment helical tomotherapy sinograms were applied on the per-treatment CTs to create a series of per-treatment dose distributions corresponding to each per-treatment CT image. In order to calculate the cumulative dose distribution, the per-treatment dose maps were non-rigidly deformed by using the deformation map computed by a non-rigid registration. The deformed dose maps were then summed in two ways: one while taking radiobiology into account and one without. These two strategies were compared using clinical surrogates in the target volumes (TV) and in surrounding organs at risk (OAR). Results: The differences between the strategies, while statistically significant (p < 0.05), are clinically irrelevant. In the OARs, the mean differences stay in the 0.01-0.07 Gy range for the total dose. In the targets, all mean differences stay in the 0.001-0.012 Gy range. However, some local high difference spots appear leading to punctual errors as high as 2.5 Gy. Conclusion: If using current radiotherapy practices and clinical recommendations based on dose surrogates computed globally on OARs and TVs, one does not need to take radiobiological effects into account while accumulating total dose as these lead to very small differences compared to a simple accumulation technique consisting of a linear sum

  8. WE-E-BRE-04: Dual Focal Spot Dose Painting for Precision Preclinical Radiobiological Investigations

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, J; Lindsay, P [Princess Margaret Cancer Centre, Toronto (Canada); University of Toronto, Toronto (Canada); Jaffray, D [Princess Margaret Cancer Centre, Toronto (Canada); The Techna Institute for the Advancement of Technology for Health, Toronto (Canada)

    2014-06-15

    Purpose: Recent progress in small animal radiotherapy systems has provided the foundation for delivering the heterogeneous, millimeter scale dose distributions demanded by preclinical radiobiology investigations. Despite advances in preclinical dose planning, delivery of highly heterogeneous dose distributions is constrained by the fixed collimation systems and large x-ray focal spot common in small animal radiotherapy systems. This work proposes a dual focal spot dose optimization and delivery method with a large x-ray focal spot used to deliver homogeneous dose regions and a small focal spot to paint spatially heterogeneous dose regions. Methods: Two-dimensional dose kernels were measured for a 1 mm circular collimator with radiochromic film at 10 mm depth in a solid water phantom for the small and large x-ray focal spots on a recently developed small animal microirradiator. These kernels were used in an optimization framework which segmented a desired dose distribution into low- and high-spatial frequency regions for delivery by the large and small focal spot, respectively. For each region, the method determined an optimal set of stage positions and beam-on times. The method was demonstrated by optimizing a bullseye pattern consisting of 0.75 mm radius circular target and 0.5 and 1.0 mm wide rings alternating between 0 and 2 Gy. Results: Compared to a large focal spot technique, the dual focal spot technique improved the optimized dose distribution: 69.2% of the optimized dose was within 0.5 Gy of the intended dose for the large focal spot, compared to 80.6% for the dual focal spot method. The dual focal spot design required 14.0 minutes of optimization, and will require 178.3 minutes for automated delivery. Conclusion: The dual focal spot optimization and delivery framework is a novel option for delivering conformal and heterogeneous dose distributions at the preclinical level and provides a new experimental option for unique radiobiological investigations

  9. WE-E-BRE-04: Dual Focal Spot Dose Painting for Precision Preclinical Radiobiological Investigations

    International Nuclear Information System (INIS)

    Stewart, J; Lindsay, P; Jaffray, D

    2014-01-01

    Purpose: Recent progress in small animal radiotherapy systems has provided the foundation for delivering the heterogeneous, millimeter scale dose distributions demanded by preclinical radiobiology investigations. Despite advances in preclinical dose planning, delivery of highly heterogeneous dose distributions is constrained by the fixed collimation systems and large x-ray focal spot common in small animal radiotherapy systems. This work proposes a dual focal spot dose optimization and delivery method with a large x-ray focal spot used to deliver homogeneous dose regions and a small focal spot to paint spatially heterogeneous dose regions. Methods: Two-dimensional dose kernels were measured for a 1 mm circular collimator with radiochromic film at 10 mm depth in a solid water phantom for the small and large x-ray focal spots on a recently developed small animal microirradiator. These kernels were used in an optimization framework which segmented a desired dose distribution into low- and high-spatial frequency regions for delivery by the large and small focal spot, respectively. For each region, the method determined an optimal set of stage positions and beam-on times. The method was demonstrated by optimizing a bullseye pattern consisting of 0.75 mm radius circular target and 0.5 and 1.0 mm wide rings alternating between 0 and 2 Gy. Results: Compared to a large focal spot technique, the dual focal spot technique improved the optimized dose distribution: 69.2% of the optimized dose was within 0.5 Gy of the intended dose for the large focal spot, compared to 80.6% for the dual focal spot method. The dual focal spot design required 14.0 minutes of optimization, and will require 178.3 minutes for automated delivery. Conclusion: The dual focal spot optimization and delivery framework is a novel option for delivering conformal and heterogeneous dose distributions at the preclinical level and provides a new experimental option for unique radiobiological investigations

  10. Deep brain stimulation of the center median-parafascicular complex of the thalamus has efficient anti-parkinsonian action associated with widespread cellular responses in the basal ganglia network in a rat model of Parkinson's disease.

    Science.gov (United States)

    Jouve, Loréline; Salin, Pascal; Melon, Christophe; Kerkerian-Le Goff, Lydia

    2010-07-21

    The thalamic centromedian-parafascicular (CM/Pf) complex, mainly represented by Pf in rodents, is proposed as an interesting target for the neurosurgical treatment of movement disorders, including Parkinson's disease. In this study, we examined the functional impact of subchronic high-frequency stimulation (HFS) of Pf in the 6-hydroxydopamine-lesioned hemiparkinsonian rat model. Pf-HFS had significant anti-akinetic action, evidenced by alleviation of limb use asymmetry (cylinder test). Whereas this anti-akinetic action was moderate, Pf-HFS totally reversed lateralized neglect (corridor task), suggesting potent action on sensorimotor integration. At the cellular level, Pf-HFS partially reversed the dopamine denervation-induced increase in striatal preproenkephalin A mRNA levels, a marker of the neurons of the indirect pathway, without interfering with the markers of the direct pathway (preprotachykinin and preprodynorphin). Pf-HFS totally reversed the lesion-induced changes in the gene expression of cytochrome oxidase subunit I in the subthalamic nucleus, the globus pallidus, and the substantia nigra pars reticulata, and partially in the entopeduncular nucleus. Unlike HFS of the subthalamic nucleus, Pf-HFS did not induce per se dyskinesias and directly, although partially, alleviated L-3,4-dihydroxyphenylalanine (L-DOPA)-induced forelimb dyskinesia. Conversely, L-DOPA treatment negatively interfered with the anti-parkinsonian effect of Pf-HFS. Altogether, these data show that Pf-DBS, by recruiting a large basal ganglia circuitry, provides moderate to strong anti-parkinsonian benefits that might, however, be affected by L-DOPA. The widespread behavioral and cellular outcomes of Pf-HFS evidenced here demonstrate that CM/Pf is an important node for modulating the pathophysiological functioning of basal ganglia and related disorders.

  11. Radiobiological basis for setting neutron radiation safety standards

    International Nuclear Information System (INIS)

    Straume, T.

    1985-01-01

    Present neutron standards, adopted more than 20 yr ago from a weak radiobiological data base, have been in doubt for a number of years and are currently under challenge. Moreover, recent dosimetric re-evaluations indicate that Hiroshima neutron doses may have been much lower than previously thought, suggesting that direct data for neutron-induced cancer in humans may in fact not be available. These recent developments make it urgent to determine the extent to which neutron cancer risk in man can be estimated from data that are available. Two approaches are proposed here that are anchored in particularly robust epidemiological and experimental data and appear most likely to provide reliable estimates of neutron cancer risk in man. The first approach uses gamma-ray dose-response relationships for human carcinogenesis, available from Nagasaki (Hiroshima data are also considered), together with highly characterized neutron and gamma-ray data for human cytogenetics. When tested against relevant experimental data, this approach either adequately predicts or somewhat overestimates neutron tumorigenesis (and mutagenesis) in animals. The second approach also uses the Nagasaki gamma-ray cancer data, but together with neutron RBEs from animal tumorigenesis studies. Both approaches give similar results and provide a basis for setting neutron radiation safety standards. They appear to be an improvement over previous approaches, including those that rely on highly uncertain maximum neutron RBEs and unnecessary extrapolations of gamma-ray data to very low doses. Results suggest that, at the presently accepted neutron dose limit of 0.5 rad/yr, the cancer mortality risk to radiation workers is not very different from accidental mortality risks to workers in various nonradiation occupations

  12. Laser-driven proton beams applied to radiobiological experiments

    International Nuclear Information System (INIS)

    Yogo, Akifumi

    2012-01-01

    The proton accelerators based on the high intensity laser system generate shorter and higher pulse beams compared to the conventional particle accelerators used for the cancer therapy. To demonstrate the radiobiological effects of the new proton beams, the program to develop a biological irradiation instrument for the DNA double-strand break was started in the fiscal year 2008. A prototype instrument was made by making use of the J-KAREN (JAEA Kansai Advanced Relativistic Engineering) laser beam. Polyimide thin film targets were used to irradiate A-549 cells. The DNA double-strand break was tested by the fluorescence spectrometry. In the second year the quantitative yield of the DNA double-strand break and its proton dose dependence were measured. The results indicated that they were comparative to the cases of the conventional particle accelerators. In the fiscal year of 2010 the design of the magnetic field for the energy selection has been changed. The new irradiation instrument, the main part of which is only about 40 cm in length as illustrated in the figure, has been constructed and tested. The experiment has been carried out using the human cancer cells (HSG) and the relative biological effectiveness (RBE) has been quantitatively evaluated by the colony assay for varied distribution of the proton beam energy. The survival fractions plotted against the dose were in good agreement with the case of 3 He beam. RBE was found not to be changed up to 1x10 7 Gy/s. Stability of the energy peak, half width and the proton density has been confirmed for this very compact instrument. (S. Funahashi)

  13. Anticancer agent CHS-828 inhibits cellular synthesis of NAD

    DEFF Research Database (Denmark)

    Olesen, U.H.; Christensen, M.K.; Bjorkling, F.

    2008-01-01

    Malignant cells display increased demands for energy production and DNA repair. Nicotinamide adenine dinucleotide (NAD) is required for both processes and is also continuously degraded by cellular enzymes. Nicotinamide phosphoribosyltransferase (Nampt) is a crucial factor in the resynthesis of NAD......, and thus in cancer cell survival. Here, we establish the cytotoxic mechanism of action of the small molecule inhibitor CHS-828 to result from impaired synthesis of NAD. Initially, we detected cross-resistance in cells between CHS-828 and a known inhibitor of Nampt, FK866, a compound of a structurally...... different class. We then showed that nicotinamide protects against CHS-828-mediated cytotoxicity. Finally, we observed that treatment with CHS-828 depletes cellular NAD levels in sensitive cancer cells. In conclusion, these results strongly suggest that, like FK866, CHS-828 kills cancer cells by depleting...

  14. The Chernobyl accident: possible pathogenic mechanisms of origination of psychical and psychosomatic disadaptation

    International Nuclear Information System (INIS)

    Gelda, A.P

    1998-01-01

    The impact of the social-psychological and biological (low doze chronic irradiation, foods unbalance, local ecological hazards) factors increase a degree of pathogen influence on organism. It is known that chronic irradiation by low dozes promotes to an increase of sensitivity to damaging action other pathogenic factors. At the same time at the special functional condition (for example, stresses), radiosensitivity of organism and a number of non radiobiological agents in combined action with radiation enhances the radiobiological effect of irradiation. Predisposing factors have a certain significance. Taking into account a real social-psychological situation the problem of medico-biological consequences of the Chernobyl accident gets the special social-medical importance

  15. An Asynchronous Cellular Automata-Based Adaptive Illumination Facility

    Science.gov (United States)

    Bandini, Stefania; Bonomi, Andrea; Vizzari, Giuseppe; Acconci, Vito

    The term Ambient Intelligence refers to electronic environments that are sensitive and responsive to the presence of people; in the described scenario the environment itself is endowed with a set of sensors (to perceive humans or other physical entities such as dogs, bicycles, etc.), interacting with a set of actuators (lights) that choose their actions (i.e. state of illumination) in an attempt improve the overall experience of these users. The model for the interaction and action of sensors and actuators is an asynchronous Cellular Automata (CA) with memory, supporting a self-organization of the system as a response to the presence and movements of people inside it. The paper will introduce the model, as well as an ad hoc user interface for the specification of the relevant parameters of the CA transition rule that determines the overall system behaviour.

  16. Cellular and molecular mechanisms of metformin: an overview

    Science.gov (United States)

    Viollet, Benoit; Guigas, Bruno; Sanz Garcia, Nieves; Leclerc, Jocelyne; Foretz, Marc; Andreelli, Fabrizio

    2012-01-01

    Considerable efforts have been made since the 1950s to better understand the cellular and molecular mechanisms of action of metformin, a potent antihyperglycemic agent now recommended as the first line oral therapy for type 2 diabetes (T2D). The main effect of this drug from the biguanide family is to acutely decrease hepatic glucose production, mostly through a mild and transient inhibition of the mitochondrial respiratory-chain complex 1. In addition, the resulting decrease in hepatic energy status activates the AMP-activated protein kinase (AMPK), a cellular metabolic sensor, providing a generally accepted mechanism for metformin action on hepatic gluconeogenic program. The demonstration that the respiratory-chain complex 1, but not AMPK, is the primary target of metformin was recently strengthened by showing that the metabolic effect of the drug is preserved in liver-specific AMPK-deficient mice. Beyond its effect on glucose metabolism, metformin was reported to restore ovarian function in polycystic ovary syndrome, reduce fatty liver and to lower microvascular and macrovascular complications associated with T2D. Its use was also recently suggested as an adjuvant treatment for cancer or gestational diabetes, and for the prevention in pre-diabetic populations. These emerging new therapeutic areas for metformin will be reviewed together with recent data from pharmacogenetic studies linking genetic variations to drug response, a promising new step towards personalized medicine in the treatment of T2D. PMID:22117616

  17. Antibody dependent cellular phagocytosis by macrophages is a novel mechanism of action of elotuzumab.

    Science.gov (United States)

    Kurdi, Ahmed T; Glavey, Siobhan V; Bezman, Natalie A; Jhatakia, Amy; Guerriero, Jennifer L; Manier, Salomon; Moschetta, Michele; Mishima, Yuji; Roccaro, Aldo; Detappe, Alexandre; Liu, Chia-Jen; Sacco, Antonio; Huynh, Daisy; Tai, Yu-Tzu; Robbins, Michael D; Azzi, Jamil; Ghobrial, Irene M

    2018-04-13

    Elotuzumab, a recently approved antibody for the treatment of multiple myeloma (MM), has been shown to stimulate Fcγ receptor (FcγR)-mediated antibody-dependent cellular cytotoxicity (ADCC) by natural killer (NK) cells towards myeloma cells. The modulatory effects of elotuzumab on other effector cells in the tumor microenvironment, however, has not been fully explored. Antibody dependent cellular phagocytosis (ADCP) is a mechanism by which macrophages contribute to anti-tumor potency of monoclonal antibodies. Herein, we studied the NK cell independent effect of elotuzumab on tumor associated macrophages (TAMs) using a xenograft tumor model deficient in NK and adaptive immune cells. We demonstrate significant anti-tumor efficacy of single agent elotuzumab in immunocompromised xenograft models of multiple myeloma, which is in part mediated by Fc-FcγR interaction of elotuzumab with macrophages. Elotuzumab is shown in this study to induce phenotypic activation of macrophages in-vivo and mediates ADCP of myeloma cells though a FcγR dependent manner in-vitro. Together, these findings propose a novel immune mediated mechanism by which elotuzumab exerts anti-myeloma activity and helps to provide rationale for combination therapies that can enhance macrophage activity. Copyright ©2018, American Association for Cancer Research.

  18. Heavy charged particle radiobiology: using enhanced biological effectiveness and improved beam focusing to advance cancer therapy.

    Science.gov (United States)

    Allen, Christopher; Borak, Thomas B; Tsujii, Hirohiko; Nickoloff, Jac A

    2011-06-03

    Ionizing radiation causes many types of DNA damage, including base damage and single- and double-strand breaks. Photons, including X-rays and γ-rays, are the most widely used type of ionizing radiation in radiobiology experiments, and in radiation cancer therapy. Charged particles, including protons and carbon ions, are seeing increased use as an alternative therapeutic modality. Although the facilities needed to produce high energy charged particle beams are more costly than photon facilities, particle therapy has shown improved cancer survival rates, reflecting more highly focused dose distributions and more severe DNA damage to tumor cells. Despite early successes of charged particle radiotherapy, there is room for further improvement, and much remains to be learned about normal and cancer cell responses to charged particle radiation. 2011 Elsevier B.V. All rights reserved.

  19. Mitochondrial electron transport is the cellular target of the oncology drug elesclomol.

    Directory of Open Access Journals (Sweden)

    Ronald K Blackman

    Full Text Available Elesclomol is a first-in-class investigational drug currently undergoing clinical evaluation as a novel cancer therapeutic. The potent antitumor activity of the compound results from the elevation of reactive oxygen species (ROS and oxidative stress to levels incompatible with cellular survival. However, the molecular target(s and mechanism by which elesclomol generates ROS and subsequent cell death were previously undefined. The cellular cytotoxicity of elesclomol in the yeast S. cerevisiae appears to occur by a mechanism similar, if not identical, to that in cancer cells. Accordingly, here we used a powerful and validated technology only available in yeast that provides critical insights into the mechanism of action, targets and processes that are disrupted by drug treatment. Using this approach we show that elesclomol does not work through a specific cellular protein target. Instead, it targets a biologically coherent set of processes occurring in the mitochondrion. Specifically, the results indicate that elesclomol, driven by its redox chemistry, interacts with the electron transport chain (ETC to generate high levels of ROS within the organelle and consequently cell death. Additional experiments in melanoma cells involving drug treatments or cells lacking ETC function confirm that the drug works similarly in human cancer cells. This deeper understanding of elesclomol's mode of action has important implications for the therapeutic application of the drug, including providing a rationale for biomarker-based stratification of patients likely to respond in the clinical setting.

  20. Recent tasks and status of National Research Institute for Radiobiology and Radiohygiene as TSO

    International Nuclear Information System (INIS)

    Pellet, S.

    2007-01-01

    The technical support function of the National Research Institute for Radiobiology and Radiohygiene has been introduced at the time of its establishment. In order to support the actual requirements the Institute carries on extended research in the fields of radiation protection and radiation biology participating in national and international projects. Supporting the proper performance of national radiation protection and safety tasks the Institute gives professional directives and expert opinions for decision processes of authorities. The Institutes main areas of radiation protection activity are: - Radiation-related licensing, inspection, record keeping; - assuring safety of radiation sources; - National Personal Dosimetry Service; - radiological monitoring of the environment; - preparedness for radiological incidents and accidents; - radiation protection training activities. The Institute has an accredited Testing Laboratory with nearly sixty examination protocols. Together with its Central Environmental Testing Laboratory, the Institute thus provides a significant support for both theoretical and practical accomplishment of the national radiation protection and safety tasks. (author)

  1. Water versus DNA: new insights into proton track-structure modelling in radiobiology and radiotherapy.

    Science.gov (United States)

    Champion, C; Quinto, M A; Monti, J M; Galassi, M E; Weck, P F; Fojón, O A; Hanssen, J; Rivarola, R D

    2015-10-21

    Water is a common surrogate of DNA for modelling the charged particle-induced ionizing processes in living tissue exposed to radiations. The present study aims at scrutinizing the validity of this approximation and then revealing new insights into proton-induced energy transfers by a comparative analysis between water and realistic biological medium. In this context, a self-consistent quantum mechanical modelling of the ionization and electron capture processes is reported within the continuum distorted wave-eikonal initial state framework for both isolated water molecules and DNA components impacted by proton beams. Their respective probability of occurrence-expressed in terms of total cross sections-as well as their energetic signature (potential and kinetic) are assessed in order to clearly emphasize the differences existing between realistic building blocks of living matter and the controverted water-medium surrogate. Consequences in radiobiology and radiotherapy will be discussed in particular in view of treatment planning refinement aiming at better radiotherapy strategies.

  2. Action mechanisms of Liver X Receptors

    Energy Technology Data Exchange (ETDEWEB)

    Gabbi, Chiara; Warner, Margaret [Center for Nuclear Receptors and Cell Signaling, University of Houston, 3056 Cullen Blv, 77204 Houston, Texas (United States); Gustafsson, Jan-Åke, E-mail: jgustafs@central.uh.edu [Center for Nuclear Receptors and Cell Signaling, University of Houston, 3056 Cullen Blv, 77204 Houston, Texas (United States); Department of Biosciences and Nutrition, Karolinska Institutet, Novum S-141 86 (Sweden)

    2014-04-11

    Highlights: • LXRα and LXRβ are ligand-activated nuclear receptors. • They share oxysterol ligands and the same heterodimerization partner, RXR. • LXRs regulate lipid and glucose metabolism, CNS and immune functions, and water transport. - Abstract: The two Liver X Receptors, LXRα and LXRβ, are nuclear receptors belonging to the superfamily of ligand-activated transcription factors. They share more than 78% homology in amino acid sequence, a common profile of oxysterol ligands and the same heterodimerization partner, Retinoid X Receptor. LXRs play crucial roles in several metabolic pathways: lipid metabolism, in particular in preventing cellular cholesterol accumulation; glucose homeostasis; inflammation; central nervous system functions and water transport. As with all nuclear receptors, the transcriptional activity of LXR is the result of an orchestration of numerous cellular factors including ligand bioavailability, presence of corepressors and coactivators and cellular context i.e., what other pathways are activated in the cell at the time the receptor recognizes its ligand. In this mini-review we summarize the factors regulating the transcriptional activity and the mechanisms of action of these two receptors.

  3. Action mechanisms of Liver X Receptors

    International Nuclear Information System (INIS)

    Gabbi, Chiara; Warner, Margaret; Gustafsson, Jan-Åke

    2014-01-01

    Highlights: • LXRα and LXRβ are ligand-activated nuclear receptors. • They share oxysterol ligands and the same heterodimerization partner, RXR. • LXRs regulate lipid and glucose metabolism, CNS and immune functions, and water transport. - Abstract: The two Liver X Receptors, LXRα and LXRβ, are nuclear receptors belonging to the superfamily of ligand-activated transcription factors. They share more than 78% homology in amino acid sequence, a common profile of oxysterol ligands and the same heterodimerization partner, Retinoid X Receptor. LXRs play crucial roles in several metabolic pathways: lipid metabolism, in particular in preventing cellular cholesterol accumulation; glucose homeostasis; inflammation; central nervous system functions and water transport. As with all nuclear receptors, the transcriptional activity of LXR is the result of an orchestration of numerous cellular factors including ligand bioavailability, presence of corepressors and coactivators and cellular context i.e., what other pathways are activated in the cell at the time the receptor recognizes its ligand. In this mini-review we summarize the factors regulating the transcriptional activity and the mechanisms of action of these two receptors

  4. Decontamination activities at the National Institute of Oncology and Radiobiology in Havana, Cuba

    International Nuclear Information System (INIS)

    Castillo, R.; Salgado, M.; Madrazo, S.; Flores, J.; Marcos, J.

    2002-01-01

    The National Institute of Oncology and Radiobiology had a facility contaminated with 137 Cs. The contamination was produced by a leaking source stored in the place. First decontamination work was performed in 1988. Some highly contaminated floor tiles and other contaminated items were removed. Spent sealed sources stored in the facility were collected. The facility was closed because of the remaining contamination. As the Regulatory Body allowed the unrestricted use of the facility, decontamination and decommissioning were needed. D and D activities were requested to the CPHR. Contamination surveys conducted in 1999 confirmed the extent of contamination with 137 Cs. Items inside the contaminated area were carefully monitored and segregated. Six Radium sources were recovered. Physical and chemical methods of decontamination were used. For different reasons, the requirements established by the Regulatory Authority for decommissioning could not be achieved, and therefore the facility could not be released from regulatory control. A Radiological Status Report was done explaining the high cost of decontamination according to the established clearance levels. New alternatives were then proposed for decommissioning of this facility. (author)

  5. An automated method for breathing frequency determination for rat lung radiobiology in BNCT

    International Nuclear Information System (INIS)

    Kiger, J.L.; Coderre, J.A.; Kiger, W.S. III

    2006-01-01

    Whole-body plethysmography was used to the measure the breathing rate in rats as a functional indication of radiation-induced lung damage, either weekly or bi-weekly for a period of 180 days following thorax irradiations in a BNCT radiobiology study. A three-minute digital breathing signal was collected in each measurement. Software has been developed to automatically discriminate against large-amplitude noise due to animal movement. After segmenting the signal into consecutive, overlapping and circular blocks, the mean frequency spectrum of the processed signal was calculated using the Fast Fourier Transform (FFT). The breathing rate was defined as the primary frequency of the spectrum and the standard deviation was estimated using the bootstrap method. The mean standard deviation of all measurements in the data set (n=4269) was 2.4%. The improved accuracy with low standard deviation of the measurements ensures good sensitivity and a low threshold for detection of responding animals; breathing rates more than 20% (∼3 σ) above the control mean were considered responding. (author)

  6. Long-term radiobiological effects in rats after exposure of 131I in utero

    Directory of Open Access Journals (Sweden)

    V. V. Talko

    2017-12-01

    Full Text Available Remote radiobiological effects in male rats prenatally exposed by 131I in different periods of gestation were studied. It was established that the negative effects of irradiation of 131I in utero in the distant period are manifested by disorders of the functioning of the pituitary-thyroid link of endocrine regulation, pro-antioxidant equilibrium, changes in the lipid-lipoprotein spectrum of blood serum. As a result of irradiation of 131I in utero throughout the period of gestation, discoordination in the functioning of the pituitary-thyroid link of endocrine regulation, a violation of the pro-antioxidant balance by increasing the intensity of lipoperoxidation processes and the activity reducing of enzymes of antioxidant defense, the atherogenic orientation of changes in the lipid-lipoprotein spectrum was established. As a result of irradiation by 131I in utero during the third trimester of gestation, the development of hypothyroidism, changes in pro-antioxidant balance due to the activation of antioxidant defense, and the reduction of the concentration of the main classes of lipids have been established.

  7. A method for radiobiological investigations in radiation fields with different LET and high dose rates

    International Nuclear Information System (INIS)

    Grundler, W.

    1976-01-01

    For investigations: 1. Performed in the field of radiobiology with different LET-radiation and a relatively high background dose rate of one component (e.g. investigations with fast and intermediate reactor neutrons) 2. Concerning radiation risk studies within a wide range 3. Of irradiations, covering a long time period (up to 100 days) a test system is necessary which on the one hand makes it possible to analyze the influence of different LET radiation and secondly shows a relative radiation resistant behaviour and allows a simple cell cycle regulation. A survey is given upon the installed device of a simple cell observation method, the biological test system used and the analysis of effects caused by dose, repair and LET. It is possible to analyze the behaviour of the nonsurvival cells and to demonstrate different reactions of the test parameters to the radiation of different LET. (author)

  8. DNA-Destabilizing Agents as an Alternative Approach for Targeting DNA: Mechanisms of Action and Cellular Consequences

    Directory of Open Access Journals (Sweden)

    Gaëlle Lenglet

    2010-01-01

    Full Text Available DNA targeting drugs represent a large proportion of the actual anticancer drug pharmacopeia, both in terms of drug brands and prescription volumes. Small DNA-interacting molecules share the ability of certain proteins to change the DNA helix's overall organization and geometrical orientation via tilt, roll, twist, slip, and flip effects. In this ocean of DNA-interacting compounds, most stabilize both DNA strands and very few display helix-destabilizing properties. These types of DNA-destabilizing effect are observed with certain mono- or bis-intercalators and DNA alkylating agents (some of which have been or are being developed as cancer drugs. The formation of locally destabilized DNA portions could interfere with protein/DNA recognition and potentially affect several crucial cellular processes, such as DNA repair, replication, and transcription. The present paper describes the molecular basis of DNA destabilization, the cellular impact on protein recognition, and DNA repair processes and the latter's relationships with antitumour efficacy.

  9. Experimental radiotherapy and clinical radiobiology. Vol. 16

    International Nuclear Information System (INIS)

    Baumann, M.; Dahm-Daphi, J.; Dikomey, E.; Petersen, C.; Rodemann, H.P.; Zips, D.

    2007-01-01

    The following topics were dealt with: DNA repair as therapeutical target in radiation therapy, biological imaging and tumor microenvironment, molecular factors of radiation therapy, molecular factors and modulation of the radiation reaction of normal tissues, experimental tumor therapy, EGFR inhibition, the endothel cell as primary target of radiation therapy, molecular and cellular foundations of the radiation biology of protons and ions. (HSI)

  10. Effects of ionizing radiation and the molecular and cellular mechanisms

    International Nuclear Information System (INIS)

    1982-01-01

    This symposium with its 60 contributions presents a survey of the current state of the art in molecular radiation biophysics and radiobiology in the FRG. Many contributions show the trend of applying findings in these fields to cancer research. The various sessions have been devoted to: 1) Radiation chemistry of biomolecules; 2) DNA damage and repair; 3) Repair of DNA damage; 4) Cell proliferation and cell inactivation; 5) Cancerogenesis, mutation and chromosomal damage; 6) Effects of heavy ions. (AJ) [de

  11. DOE life-span radiation effects studies in experimental animals at University of Utah Division of Radiobiology

    International Nuclear Information System (INIS)

    Wrenn, M.E.; Taylor, G.N.; Stevens, W.

    1986-01-01

    The Radiobiology Laboratory at the University of Utah compared the long-term biological effects of 226 Ra and 239 Pu in adult beagles. The program includes the investigation of other radionuclides. More recently, groups of juvenile and aged beagles were added to the study to investigate the influence of age at exposure. These studies involved single intravenous injection of radionuclides to small groups of beagles, in graded doses from levels at which no effects were expected up to levels where a 100% incidence of bone tumors was sometimes found. Some of the principal effects were bone tumors, fractures, and other skeletal alterations observed radiographically and histologically; emphasis was placed on the detection of precancerous changes, hematological changes, and changes related to aging. Emphasis was also placed on metabolic and autoradiographic studies necessary for good radiation dosimetry

  12. Antibacterial Activity and Mode of Action of Mentha arvensis Ethanol ...

    African Journals Online (AJOL)

    Antibacterial Activity and Mode of Action of Mentha arvensis Ethanol Extract against ... the antibacterial effect of ethanol extract of Mentha arvensis against multi-drug ... Reactive oxygen species (ROS) generation and protein leakage from the ... A. baumannii and acts by inducing lethal cellular damage to the bacterium.

  13. AFRRI (Armed Forces Radiobiology Research Institute) Reports, October, January-March 1989

    Science.gov (United States)

    1989-01-01

    conservative synthesis 1,ir 301 mitn at room temperature. the MimxtUre wit’ centri- during the time allowed for repair. The photolysis tu~ get t1 2001i) g it...differeccs in rccow rv at thc cellular level. oft proteinas anrd iolher mnoleculecs to nucleic acids. In In Radiation andi Cellular C onio-ol Prmnt.ie

  14. The role of surface charge in cellular uptake and cytotoxicity of medical nanoparticles

    Directory of Open Access Journals (Sweden)

    Fröhlich E

    2012-11-01

    Full Text Available Eleonore FröhlichCenter for Medical Research, Medical University of Graz, Graz, AustriaAbstract: Many types of nanoparticles (NPs are tested for use in medical products, particularly in imaging and gene and drug delivery. For these applications, cellular uptake is usually a prerequisite and is governed in addition to size by surface characteristics such as hydrophobicity and charge. Although positive charge appears to improve the efficacy of imaging, gene transfer, and drug delivery, a higher cytotoxicity of such constructs has been reported. This review summarizes findings on the role of surface charge on cytotoxicity in general, action on specific cellular targets, modes of toxic action, cellular uptake, and intracellular localization of NPs. Effects of serum and intercell type differences are addressed. Cationic NPs cause more pronounced disruption of plasma-membrane integrity, stronger mitochondrial and lysosomal damage, and a higher number of autophagosomes than anionic NPs. In general, nonphagocytic cells ingest cationic NPs to a higher extent, but charge density and hydrophobicity are equally important; phagocytic cells preferentially take up anionic NPs. Cells do not use different uptake routes for cationic and anionic NPs, but high uptake rates are usually linked to greater biological effects. The different uptake preferences of phagocytic and nonphagocytic cells for cationic and anionic NPs may influence the efficacy and selectivity of NPs for drug delivery and imaging.Keywords: endocytosis, plasma membrane, lysosomes, polystyrene particles, quantum dots, dendrimers

  15. Interplay of drug metabolizing enzymes with cellular transporters.

    Science.gov (United States)

    Böhmdorfer, Michaela; Maier-Salamon, Alexandra; Riha, Juliane; Brenner, Stefan; Höferl, Martina; Jäger, Walter

    2014-11-01

    Many endogenous and xenobiotic substances and their metabolites are substrates for drug metabolizing enzymes and cellular transporters. These proteins may not only contribute to bioavailability of molecules but also to uptake into organs and, consequently, to overall elimination. The coordinated action of uptake transporters, metabolizing enzymes, and efflux pumps, therefore, is a precondition for detoxification and elimination of drugs. As the understanding of the underlying mechanisms is important to predict alterations in drug disposal, adverse drug reactions and, finally, drug-drug interactions, this review illustrates the interplay between selected uptake/efflux transporters and phase I/II metabolizing enzymes.

  16. New methodologies of biological dosimetry applied to human protection

    International Nuclear Information System (INIS)

    Catena, C.; Parasacchi, P.; Conti, D.; Righi, E.

    1995-04-01

    Biological dosimetry is a diagnostic methodology for the measurement of the individual dose absorbed in the case of accidental overexposition to ionizing radiation. It is demonstrated how in vitro radiobiological and chemobiological studies using cytogenetic methods (count of chromosomal aberrations and micronuclei) on human lymphocytes from healthy subjects and individuals undergoing radiotherapy or chemotherapy, as well as on lymphocytes of mammals other than man (comparative cytogenetics), can help to increase the basic radiobiological and chemobiological scientific information. Such information gives a valid contribution to understanding of the action of ionizing radiation or of pharmaceuticals on cells and, in return, can be of value to human radioprotection and chemoprotection. Cytogenetic studies can be summerized as follows: a) biodosimetry (estimate of dose received after accidental events); b) individual radiosensitivity (level of individual response); c) clinical radiobiology and chemobiology (individual response to radiopharmaceuticals, to radiotherapy and to chemopharmaceuticals); d) comparative radiobiology (cytogenetic studies on species other than man); e) animal model in the environmental surveillance

  17. Evaluation of the Cytotoxicity and Genotoxicity of Flavonolignans in Different Cellular Models

    Directory of Open Access Journals (Sweden)

    Michal Bijak

    2017-12-01

    Full Text Available Flavonolignans are the main components of silymarin, which represents 1.5–3% of the dry fruit weight of Milk thistle (Silybum marianum L. Gaernt.. In ancient Greece and Romania, physicians and herbalists used the Silybum marianum to treat a range of liver diseases. Besides their hepatoprotective action, silymarin flavonolignans have many other healthy properties, such as anti-platelet and anti-inflammatory actions. The aim of this study was to evaluate the toxic effect of flavonolignans on blood platelets, peripheral blood mononuclear cells (PBMCs and human lung cancer cell line—A549—using different molecular techniques. We established that three major flavonolignans: silybin, silychristin and silydianin, in concentrations of up to 100 µM, have neither a cytotoxic nor genotoxic effect on blood platelets, PMBCs and A549. We also saw that silybin and silychristin have a protective effect on cellular mitochondria, observed as a reduction of spontaneous mitochondrial DNA (mtDNA damage in A549, measured as mtDNA copies, and mtDNA lesions in ND1 and ND5 genes. Additionally, we observed that flavonolignans increase the blood platelets’ mitochondrial membrane potential and reduce the generation of reactive oxygen species in blood platelets. Our current findings show for the first time that the three major flavonolignans, silybin, silychristin and silydianin, do not have any cytotoxicity and genotoxicity in various cellular models, and that they actually protect cellular mitochondria. This proves that the antiplatelet and anti-inflammatory effect of these compounds is part of our molecular health mechanisms.

  18. Cellular dynamical mechanisms for encoding the time and place of events along spatiotemporal trajectories in episodic memory.

    Science.gov (United States)

    Hasselmo, Michael E; Giocomo, Lisa M; Brandon, Mark P; Yoshida, Motoharu

    2010-12-31

    Understanding the mechanisms of episodic memory requires linking behavioral data and lesion effects to data on the dynamics of cellular membrane potentials and population interactions within brain regions. Linking behavior to specific membrane channels and neurochemicals has implications for therapeutic applications. Lesions of the hippocampus, entorhinal cortex and subcortical nuclei impair episodic memory function in humans and animals, and unit recording data from these regions in behaving animals indicate episodic memory processes. Intracellular recording in these regions demonstrates specific cellular properties including resonance, membrane potential oscillations and bistable persistent spiking that could underlie the encoding and retrieval of episodic trajectories. A model presented here shows how intrinsic dynamical properties of neurons could mediate the encoding of episodic memories as complex spatiotemporal trajectories. The dynamics of neurons allow encoding and retrieval of unique episodic trajectories in multiple continuous dimensions including temporal intervals, personal location, the spatial coordinates and sensory features of perceived objects and generated actions, and associations between these elements. The model also addresses how cellular dynamics could underlie unit firing data suggesting mechanisms for coding continuous dimensions of space, time, sensation and action. Copyright © 2010 Elsevier B.V. All rights reserved.

  19. SU-F-T-670: From the OR to the Radiobiology Lab: The Journey of a Small X-Ray Source

    Energy Technology Data Exchange (ETDEWEB)

    Lehmann, J [Calvary Mater, Newcastle, NSW (Australia); The University of Sydney, Sydney, NSW (Australia); The University of Newcastle, Newcastle, NSW (Australia); Barry, M; Jones, R; Fay, M [Calvary Mater, Newcastle, NSW (Australia)

    2016-06-15

    Purpose: Irradiation of small animal tumor models within laboratories is vital to radiobiological experiments. Often the animals are not able to be brought back into the lab after being taken out for irradiation. Cell biology laboratories benefit from irradiation capability available around the clock without regard to patient load in an associated radiotherapy clinic. Commercial systems are available, but bulky and expensive. Methods: An intraoperative kV irradiation system (IntraBeam™) designed to deliver spherical dose distributions to surgical cavities has been repurposed for the irradiation of cell plates and small laboratory animals. An applicator has been altered to allow for simple, open fields. Special collimators are being developed. BEAMnrc Monte Carlo simulations with the “NRC swept BEAM” source model have been performed to characterize the dose distributions, to develop optimal collimators and as basis for dose prescription. Measurements with radiochromic film and with an ionization chamber were performed to characterize the beam and to validate the simulations. Results: Using its highest setting (50 kV and 40 µA) the x-ray unit is capable of delivering dose rates over 1 Gy/min homogeneously to standard cell plates even without an optimized collimator. Smaller areas (tumors in animals) can be irradiated with significantly higher dose rates (> 20 Gy/min) depending on distance of the source to the tumor. The HVL was found to be 0.21 mm Al which means the shielding requirements for the device are easily achievable in the lab. Conclusion: A mobile irradiation facility is feasible. It will allow easier access to radiation for radiobiology experiments. The modified system is versatile in that for cell plates homogenous irradiations can be achieved through distance from the source, while for high dose rate small field irradiations the source can be brought in close proximity to the target.

  20. Topology optimization of adaptive fluid-actuated cellular structures with arbitrary polygonal motor cells

    International Nuclear Information System (INIS)

    Lv, Jun; Tang, Liang; Li, Wenbo; Liu, Lei; Zhang, Hongwu

    2016-01-01

    This paper mainly focuses on the fast and efficient design method for plant bioinspired fluidic cellular materials and structures composed of polygonal motor cells. Here we developed a novel structural optimization method with arbitrary polygonal coarse-grid elements based on multiscale finite element frameworks. The fluidic cellular structures are meshed with irregular polygonal coarse-grid elements according to their natural size and the shape of the imbedded motor cells. The multiscale base functions of solid displacement and hydraulic pressure are then constructed to bring the small-scale information of the irregular motor cells to the large-scale simulations on the polygonal coarse-grid elements. On this basis, a new topology optimization method based on the resulting polygonal coarse-grid elements is proposed to determine the optimal distributions or number of motor cells in the smart cellular structures. Three types of optimization problems are solved according to the usages of the fluidic cellular structures. Firstly, the proposed optimization method is utilized to minimize the system compliance of the load-bearing fluidic cellular structures. Second, the method is further extended to design biomimetic compliant actuators of the fluidic cellular materials due to the fact that non-uniform volume expansions of fluid in the cells can induce elastic action. Third, the optimization problem focuses on the weight minimization of the cellular structure under the constraints for the compliance of the whole system. Several representative examples are investigated to validate the effectiveness of the proposed polygon-based topology optimization method of the smart materials. (paper)

  1. Toxicological characteristics and primary radiobiological screening of Cystizid-M

    International Nuclear Information System (INIS)

    Minkova, M.; Pantev, T.; Georgieva, R.

    1987-01-01

    The toxic and radioprotective properties of the potential radioprotector of the mollecular combination Cystisid-M (cysteamine-adenosin-5'-monophosphate - CAM) were investigated. The experiments were carried out on male mice C 57 BI irradiated with 137 Cs source. The intraperitoneal administration of 1000 mg/kg b.w. and 500 mg/kg b.w., injected 15 min prior to the irradiation with 8,5 Gr (LD 90/30 ) was performed, and orally 3000 mg/kg b.w. and 1500 mg/kg b.w. was introduced into the stomach 45 min prior to the irradiation with 8,2 Gr (LD 83/30 ). The radioprotective effect of CAM was recorded according to: individual survival curves up to the 30th day; the biometrical coefficients 'ALPHA' (the individual survival expectancy in the population); and S 30 (the group survival expectancy). At the intraperitoneal administration of the protector the values of LD 50 = 1390 mg/kg b.w. and MPD (maximum permissible dose) = 1200 mg/kg b.w. were found. At the oral administration these doses were LD 50/3 = 4630 mg/kg b.w. and MPD = 3500 mg/kg b.w. It was established that CAM injected intraperitoneally in a dose of 1000 mg/kg b.w. ensured 75% survival of the protected mice against 10% of the control ones, increased the mean survival of the deceased and reduced the percentage of the animals died during the height of the bone marrow syndrome. The twofold lower dose exetted a considerably slighter effect. At oral administration the protector did not significantly modify the survival of the animals. The data obtained revealed the perspectiveness of the tested protective agent radiobiological investigations are required

  2. Population of computational rabbit-specific ventricular action potential models for investigating sources of variability in cellular repolarisation.

    Directory of Open Access Journals (Sweden)

    Philip Gemmell

    Full Text Available Variability is observed at all levels of cardiac electrophysiology. Yet, the underlying causes and importance of this variability are generally unknown, and difficult to investigate with current experimental techniques. The aim of the present study was to generate populations of computational ventricular action potential models that reproduce experimentally observed intercellular variability of repolarisation (represented by action potential duration and to identify its potential causes. A systematic exploration of the effects of simultaneously varying the magnitude of six transmembrane current conductances (transient outward, rapid and slow delayed rectifier K(+, inward rectifying K(+, L-type Ca(2+, and Na(+/K(+ pump currents in two rabbit-specific ventricular action potential models (Shannon et al. and Mahajan et al. at multiple cycle lengths (400, 600, 1,000 ms was performed. This was accomplished with distributed computing software specialised for multi-dimensional parameter sweeps and grid execution. An initial population of 15,625 parameter sets was generated for both models at each cycle length. Action potential durations of these populations were compared to experimentally derived ranges for rabbit ventricular myocytes. 1,352 parameter sets for the Shannon model and 779 parameter sets for the Mahajan model yielded action potential duration within the experimental range, demonstrating that a wide array of ionic conductance values can be used to simulate a physiological rabbit ventricular action potential. Furthermore, by using clutter-based dimension reordering, a technique that allows visualisation of multi-dimensional spaces in two dimensions, the interaction of current conductances and their relative importance to the ventricular action potential at different cycle lengths were revealed. Overall, this work represents an important step towards a better understanding of the role that variability in current conductances may play in

  3. Population of computational rabbit-specific ventricular action potential models for investigating sources of variability in cellular repolarisation.

    Science.gov (United States)

    Gemmell, Philip; Burrage, Kevin; Rodriguez, Blanca; Quinn, T Alexander

    2014-01-01

    Variability is observed at all levels of cardiac electrophysiology. Yet, the underlying causes and importance of this variability are generally unknown, and difficult to investigate with current experimental techniques. The aim of the present study was to generate populations of computational ventricular action potential models that reproduce experimentally observed intercellular variability of repolarisation (represented by action potential duration) and to identify its potential causes. A systematic exploration of the effects of simultaneously varying the magnitude of six transmembrane current conductances (transient outward, rapid and slow delayed rectifier K(+), inward rectifying K(+), L-type Ca(2+), and Na(+)/K(+) pump currents) in two rabbit-specific ventricular action potential models (Shannon et al. and Mahajan et al.) at multiple cycle lengths (400, 600, 1,000 ms) was performed. This was accomplished with distributed computing software specialised for multi-dimensional parameter sweeps and grid execution. An initial population of 15,625 parameter sets was generated for both models at each cycle length. Action potential durations of these populations were compared to experimentally derived ranges for rabbit ventricular myocytes. 1,352 parameter sets for the Shannon model and 779 parameter sets for the Mahajan model yielded action potential duration within the experimental range, demonstrating that a wide array of ionic conductance values can be used to simulate a physiological rabbit ventricular action potential. Furthermore, by using clutter-based dimension reordering, a technique that allows visualisation of multi-dimensional spaces in two dimensions, the interaction of current conductances and their relative importance to the ventricular action potential at different cycle lengths were revealed. Overall, this work represents an important step towards a better understanding of the role that variability in current conductances may play in experimentally

  4. Radiobiological mechanisms of stereotactic body radiation therapy and stereotactic radiation surgery

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Mi Sook; Kim, Won Woo; Park, In Hwan; Kim, Hee Jong; Lee, Eun Jin; Jung, Jae Hoon [Research Center for Radiotherapy, Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of); Cho, Lawrence Chin Soo; Song, Chang W. [Dept. of Radiation Oncology, University of Minnesota Medical School, Minneapolis (United States)

    2015-12-15

    Despite the increasing use of stereotactic body radiation therapy (SBRT) and stereotactic radiation surgery (SRS) in recent years, the biological base of these high-dose hypo-fractionated radiotherapy modalities has been elusive. Given that most human tumors contain radioresistant hypoxic tumor cells, the radiobiological principles for the conventional multiple-fractionated radiotherapy cannot account for the high efficacy of SBRT and SRS. Recent emerging evidence strongly indicates that SBRT and SRS not only directly kill tumor cells, but also destroy the tumor vascular beds, thereby deteriorating intratumor microenvironment leading to indirect tumor cell death. Furthermore, indications are that the massive release of tumor antigens from the tumor cells directly and indirectly killed by SBRT and SRS stimulate anti-tumor immunity, thereby suppressing recurrence and metastatic tumor growth. The reoxygenation, repair, repopulation, and redistribution, which are important components in the response of tumors to conventional fractionated radiotherapy, play relatively little role in SBRT and SRS. The linear-quadratic model, which accounts for only direct cell death has been suggested to overestimate the cell death by high dose per fraction irradiation. However, the model may in some clinical cases incidentally do not overestimate total cell death because high-dose irradiation causes additional cell death through indirect mechanisms. For the improvement of the efficacy of SBRT and SRS, further investigation is warranted to gain detailed insights into the mechanisms underlying the SBRT and SRS.

  5. Cellular gravity

    NARCIS (Netherlands)

    F.C. Gruau; J.T. Tromp (John)

    1999-01-01

    textabstractWe consider the problem of establishing gravity in cellular automata. In particular, when cellular automata states can be partitioned into empty, particle, and wall types, with the latter enclosing rectangular areas, we desire rules that will make the particles fall down and pile up on

  6. Large field radiotherapy

    International Nuclear Information System (INIS)

    Vanasek, J.; Chvojka, Z.; Zouhar, M.

    1984-01-01

    Calculations may prove that irradiation procedures, commonly used in radiotherapy and represented by large-capacity irradiation techniques, do not exceed certain limits of integral doses with favourable radiobiological action on the organism. On the other hand integral doses in supralethal whole-body irradiation, used in the therapy of acute leukemia, represent radiobiological values which without extreme and exceptional further interventions and teamwork are not compatible with life, and the radiotherapeutist cannot use such high doses without the backing of a large team. (author)

  7. Irradiations of human melanoma cells by 14 MeV neutrons; survival curves interpretation; physical simulation of neutrons interactions in the cellular medium

    International Nuclear Information System (INIS)

    Bodez, Veronique

    2000-01-01

    14 MeV neutrons are used to irradiate human melanoma cells in order to study survival curves at low dose and low dose rate. We have simulated with the MCNP code, transport of neutrons through the experimental setup to evaluate the contamination of the primary beam by gamma and electrons, for the feasibility of our experiments. We have shown a rapid decrease of the survival curve in the first cGy followed by a plateau for doses up to 30 cGy; after we observed an exponential decrease. This results are observed for the first time, for neutrons at low dose rate (5 cGy/h). In parallel with this experimental point, we have developed a simulation code which permitted the study of neutrons interactions with the cellular medium for individual cells defined as in our experimental conditions. We show that most of the energy is deposited by protons from neutron interactions with external medium, and by heavy ions for interactions into the cell. On the other hand the code gives a good order of magnitude of the dose rate, compared to the experimental values given by silicon diodes. The first results show that we can, using a theory based on induced repair of cells, give an interpretation of the observed experimental plateau. We can give an estimation of the radial distribution of dose for the tracks of charged ions, we show the possibility of calculate interaction cross sections with cellular organelles. Such a work gives interesting perspectives for the future in radiobiology, radiotherapy or radioprotection. (author) [fr

  8. [Radiobiology research.] Annual report, fiscal year 1984

    International Nuclear Information System (INIS)

    1985-11-01

    This report summarizes research activities for the period from 1 October 1983 to 30 September 1984 at the Laboratory for Energy-related Health Research (LEHR). This report has been divided into several topical sections outlining the scope of research at LEHR including ''Radionuclide Toxicity Studies,'' ''External Radiation Effect Studies,'' ''Skeletal Biology Studies,'' ''Cellular and Molecular Studies,'' ''Biomedical and Toxicological Studies,'' ''Physical and Chemical Studies,'' and ''Nuclear Medical Studies.''

  9. Monte Carlo dose calculations and radiobiological modelling: analysis of the effect of the statistical noise of the dose distribution on the probability of tumour control

    International Nuclear Information System (INIS)

    Buffa, Francesca M.

    2000-01-01

    The aim of this work is to investigate the influence of the statistical fluctuations of Monte Carlo (MC) dose distributions on the dose volume histograms (DVHs) and radiobiological models, in particular the Poisson model for tumour control probability (tcp). The MC matrix is characterized by a mean dose in each scoring voxel, d, and a statistical error on the mean dose, σ d ; whilst the quantities d and σ d depend on many statistical and physical parameters, here we consider only their dependence on the phantom voxel size and the number of histories from the radiation source. Dose distributions from high-energy photon beams have been analysed. It has been found that the DVH broadens when increasing the statistical noise of the dose distribution, and the tcp calculation systematically underestimates the real tumour control value, defined here as the value of tumour control when the statistical error of the dose distribution tends to zero. When increasing the number of energy deposition events, either by increasing the voxel dimensions or increasing the number of histories from the source, the DVH broadening decreases and tcp converges to the 'correct' value. It is shown that the underestimation of the tcp due to the noise in the dose distribution depends on the degree of heterogeneity of the radiobiological parameters over the population; in particular this error decreases with increasing the biological heterogeneity, whereas it becomes significant in the hypothesis of a radiosensitivity assay for single patients, or for subgroups of patients. It has been found, for example, that when the voxel dimension is changed from a cube with sides of 0.5 cm to a cube with sides of 0.25 cm (with a fixed number of histories of 10 8 from the source), the systematic error in the tcp calculation is about 75% in the homogeneous hypothesis, and it decreases to a minimum value of about 15% in a case of high radiobiological heterogeneity. The possibility of using the error on the

  10. Cardiac endothelial cells isolated from mouse heart - a novel model for radiobiology

    International Nuclear Information System (INIS)

    Jelonek, K.; Walaszczyk, A.; Gabrys, D.; Pietrowska, M.; Widlak, P.; Kanthou, Ch.

    2011-01-01

    Cardiovascular disease is recognized as an important clinical problem in radiotherapy and radiation protection. However, only few radiobiological models relevant for assessment of cardiotoxic effects of ionizing radiation are available. Here we describe the isolation of mouse primary cardiac endothelial cells, a possible target for cardiotoxic effects of radiation. Cells isolated from hearts of juvenile mice were cultured and irradiated in vitro. In addition, cells isolated from hearts of locally irradiated adult animals (up to 6 days after irradiation) were tested. A dose-dependent formation of histone γH 2 A.X foci was observed after in vitro irradiation of cultured cells. However, such cells were resistant to radiation-induced apoptosis. Increased levels of actin stress fibres were observed in the cytoplasm of cardiac endothelial cells irradiated in vitro or isolated from irradiated animals. A high dose of 16 Gy did not increase permeability to Dextran in monolayers formed by endothelial cells. Up-regulated expression of Vcam1, Sele and Hsp70i genes was detected after irradiation in vitro and in cells isolated few days after irradiation in vivo. The increased level of actin stress fibres and enhanced expression of stress-response genes in irradiated endothelial cells are potentially involved in cardiotoxic effects of ionizing radiation. (authors)

  11. Development of a single ion micro-irradiation facility for experimental radiobiology at cell level

    International Nuclear Information System (INIS)

    Barberet, Ph.

    2003-10-01

    A micro-irradiation device has been developed for radiobiology applications at the scale of the cell. This device is based on an upgrade of an existing micro-beam line that was already able to deliver a 1 to 3 MeV proton or alpha beam of low intensity and whose space resolution is lower than 1 micrometer in vacuum. The important part of this work has been the development of an irradiation stage designed to fit on the micro-probe and able to deliver ions in the air with an absolute accuracy of a few micrometers. A program has been set up to monitor the complete irradiation line in testing and in automatic irradiation operating phases. Simulation tools based on Monte-Carlo calculations have been validated through comparisons with experimental data particularly in the field of spatial resolution and of the number of ions delivered. The promising results show the possibility in a near future to use this tool to study the response of cells to very low irradiation doses down to the extreme limit of one ion per cell

  12. Radiobiology in clinical radiation therapy - Part I: Systems and principles

    International Nuclear Information System (INIS)

    Hall, Eric J.

    1997-01-01

    Objective: This course is designed for residents in radiation oncology, preparing for their boards. It begins with the principles of cell and molecular biology as they relate to carcinogenesis, and concentrates on the principles of radiation biology that have been established by the use of quantitative biological systems. Malignant cells are characterized by their capacity for unlimited proliferation; this change from normal cells is the consequence of genetic changes that may include the activation of dominantly acting oncogenes and/or the deletion of recessively acting tumor suppressor genes. The biological effects of radiation may result from the direct action, which refers to ionizations in the DNA itself, or the indirect action which is mediated by free radicals. Radiation-induced DNA damage may lead to carcinogenesis and hereditary effects, which are important in personnel protection, or to cell lethality which is the basis of radiotherapy. Chromosome aberrations and cell lethality appear to result from the interaction of two lesions (probably double strand breaks) which leads to the ubiquitous linear-quadratic relationship. This refers to mitotic death, which is the most common form of radiation induced death. Programmed cell death or Apoptosis also occurs which is important in more radiosensitive tumors, and relatively unimportant in radioresistant tumors. A number of quantitative biological test systems have been developed to quantify the effects of radiation as a function of dose. Cells may be cultured in vitro, of normal and neoplastic origin, and survival curves produced with reproductive integrity plotted as a function of dose. Normal tissue systems where reproductive integrity can be scored as an endpoint include skin, gut, colony forming units in the bone marrow, as well as breast, thyroid and testis. The response of some normal tissues depends, not only on the fraction of cells killed, but on the tissue architecture in terms of functional subunits

  13. Differential Action between Schisandrin A and Schisandrin B in Eliciting an Anti-Inflammatory Action: The Depletion of Reduced Glutathione and the Induction of an Antioxidant Response.

    Directory of Open Access Journals (Sweden)

    Pou Kuan Leong

    Full Text Available Schisandrin A (Sch A and schisandrin B (Sch B are active components of Schisandrae Fructus. We compared the biochemical mechanism underlying the anti-inflammatory action of Sch A and Sch B, using cultured lipopolysaccharide (LPS-stimulated RAW264.7 macrophages and concanavalin (ConA-stimulated mouse splenocytes. Pre-incubation with Sch A or Sch B produced an anti-inflammatory action in LPS-stimulated RAW264.7 cells, as evidenced by the inhibition of the pro-inflammatory c-Jun N-terminal kinases/p38 kinase/nuclear factor-κB signaling pathway as well as the suppression of various pro-inflammatory cytokines and effectors, with the extent of inhibition by Sch A being more pronounced. The greater activity of Sch A in anti-inflammatory response was associated with a greater decrease in cellular reduced glutathione (GSH level and a greater increase in glutathione S-transferase activity than corresponding changes produced by Sch B. However, upon incubation, only Sch B resulted in the activation of the nuclear factor (erythroid-derived 2-like factor 2 and the induction of a significant increase in the expression of thioredoxin (TRX in RAW264.7 cells. The Sch B-induced increase in TRX expression was associated with the suppression of pro-inflammatory cytokines and effectors in LPS-stimulated macrophages. Studies in a mouse model of inflammation (carrageenan-induced paw edema indicated that while long-term treatment with either Sch A or Sch B suppressed the extent of paw edema, only acute treatment with Sch A produced a significant degree of inhibition on the inflammatory response. Although only Sch A decreased the cellular GSH level and suppressed the release of pro-inflammatory cytokines and cell proliferation in ConA-simulated splenocytes in vitro, both Sch A and Sch B treatments, while not altering cellular GSH levels, suppressed ConA-stimulated splenocyte proliferation ex vivo. These results suggest that Sch A and Sch B may act differentially on

  14. Study on cellular survival adaptive response induced by low dose irradiation of 153Sm

    International Nuclear Information System (INIS)

    Zhu Shoupeng; Xiao Dong

    1999-01-01

    The present study engages in determining whether low dose irradiation of 153 Sm could cut down the responsiveness of cellular survival to subsequent high dose exposure of 153 Sm so as to make an inquiry into approach the protective action of adaptive response by second irradiation of 153 Sm. Experimental results indicate that for inductive low dose of radionuclide 153 Sm 3.7 kBq/ml irradiated beforehand to cells has obvious resistant effect in succession after high dose irradiation of 153 Sm 3.7 x 10 2 kBq/ml was observed. Cells exposed to low dose irradiation of 153 Sm become adapted and therefore the subsequent cellular survival rate induced by high dose of 153 Sm is sufficiently higher than high dose of 153 Sm merely. It is evident that cellular survival adaptive response could be induced by pure low dose irradiation of 153 Sm only

  15. Inhibitory effects of OK-432 (Picibanil) on cellular proliferation and adhesive capacity of breast carcinoma cells.

    Science.gov (United States)

    Horii, Yoshio; Iino, Yuichi; Maemura, Michio; Horiguchi, Jun; Morishita, Yasuo

    2005-02-01

    We investigated the potent inhibitory effects of OK-432 (Picibanil) on both cellular adhesion and cell proliferation of estrogen-dependent (MCF-7) or estrogen-independent (MDA-MB-231) breast carcinoma cells. Cellular proliferation of both MCF-7 and MDA-MB-231 cells was markedly inhibited in a dose-dependent manner, when the carcinoma cells were exposed to OK-432. Cell attachment assay demonstrated that incubation with OK-432 for 24 h reduced integrin-mediated cellular adhesion of both cell types. However, fluorescence activated cell sorter (FACS) analysis revealed that incubation with OK-432 for 24 h did not decrease the cell surface expressions of any integrins. These results suggest that the binding avidity of integrins is reduced by OK-432 without alteration of the integrin expression. We conclude that OK-432 inhibits integrin-mediated cellular adhesion as well as cell proliferation of breast carcinoma cells regardless of estrogen-dependence, and that these actions of OK-432 contribute to prevention or inhibition of breast carcinoma invasion and metastasis.

  16. Zinc Transporters, Mechanisms of Action and Therapeutic Utility: Implications for Type 2 Diabetes Mellitus

    Directory of Open Access Journals (Sweden)

    Stephen A. Myers

    2012-01-01

    Full Text Available Zinc is an essential trace element that plays a vital role in maintaining many biological processes and cellular homeostasis. Dysfunctional zinc signaling is associated with a number of chronic disease states including cancer, cardiovascular disease, Alzheimer’s disease, and diabetes. Cellular homeostasis requires mechanisms that tightly control the uptake, storage, and distribution of zinc. This is achieved through the coordinated actions of zinc transporters and metallothioneins. Evidence on the role of these proteins in type 2 diabetes mellitus (T2DM is now emerging. Zinc plays a key role in the synthesis, secretion and action of insulin in both physiological and pathophysiological states. Moreover, recent studies highlight zinc’s dynamic role as a “cellular second messenger” in the control of insulin signaling and glucose homeostasis. This suggests that zinc plays an unidentified role as a novel second messenger that augments insulin activity. This previously unexplored concept would raise a whole new area of research into the pathophysiology of insulin resistance and introduce a new class of drug target with utility for diabetes pharmacotherapy.

  17. Link between physics and biology

    International Nuclear Information System (INIS)

    Zaider, M.; Brenner, D.J.; Hall, E.J.; Kliauga, P.

    1988-01-01

    In the general causative chain: radiation physics-radiation chemistry - radiobiology - cancer treatment, physics, the initiating and therefore cardinal agent, continues to play the role of the poor relation. The main reason for this state of affairs rests with the fact that most models of radiation action - the actual link between physics and biology - make very little or no use of information concerning the radiation field: they are simply convenient vehicles for describing a large body of radiobiological data with analytical expressions containing a minimum number of parameters. In spite of their practical usefulness such models will not be further considered here. It is a reasonable assertion that the main goal of radiation biophysics is to elucidate the mechanisms of radiation action on biological entities

  18. Low LET protons focused to submicrometer shows enhanced radiobiological effectiveness

    Science.gov (United States)

    Schmid, T. E.; Greubel, C.; Hable, V.; Zlobinskaya, O.; Michalski, D.; Girst, S.; Siebenwirth, C.; Schmid, E.; Molls, M.; Multhoff, G.; Dollinger, G.

    2012-10-01

    This study shows that enhanced radiobiological effectiveness (RBE) values can be generated focusing low linear energy transfer (LET) radiation and thus changing the microdose distribution. 20 MeV protons (LET = 2.65 keV µm-1) are focused to submicrometer diameter at the ion microprobe superconducting nanoprobe for applied nuclear (Kern) physics experiments of the Munich tandem accelerator. The RBE values, as determined by measuring micronuclei (RBEMN = 1.48 ± 0.07) and dicentrics (RBED = 1.92 ± 0.15), in human-hamster hybrid (AL) cells are significantly higher when 117 protons were focused to a submicrometer irradiation field within a 5.4 × 5.4 µm2 matrix compared to quasi homogeneous in a 1 × 1 µm2 matrix applied protons (RBEMN = 1.28 ± 0.07; RBED = 1.41 ± 0.14) at the same average dose of 1.7 Gy. The RBE values are normalized to standard 70 kV (dicentrics) or 200 kV (micronuclei) x-ray irradiation. The 117 protons applied per point deposit the same amount of energy like a 12C ion with 55 MeV total energy (4.48 MeV u-1). The enhancements are about half of that obtained for 12C ions (RBEMN = 2.20 ± 0.06 and RBED = 3.21 ± 0.10) and they are attributed to intertrack interactions of the induced damages. The measured RBE values show differences from predictions of the local effect model (LEM III) that is used to calculate RBE values for irradiation plans to treat tumors with high LET particles.

  19. Testosterone deficiency syndrome: cellular and molecular mechanism of action.

    Science.gov (United States)

    Carruthers, Malcolm

    2013-02-01

    There is virtually no correlation between what are generally accepted to be the symptoms of deficient androgen in men and levels of androgens as measured in the laboratory. Now that androgen deficiency is being shown to play a part in conditions as diverse as metabolic syndrome, diabetes, and coronary heart disease, a hypothesis is needed to explain this apparent discrepancy between measured androgen levels and our understanding of the symptoms of androgen deficiency. When the possible mechanisms for androgen actions are considered, one explanation emerges that androgen may act much like insulin in persons with type 2 diabetes mellitus: the degree of androgen resistance may be variable depending on the organs or systems considered. Therefore, the symptoms can result from altered or damaged synthesis of androgen synthesis or regulation, elevated androgen binding, a reduction in tissue response, or decreased as a result of polymorphism and aging. Genomic transcription and translation may also be affected. As with diabetes, in adult male androgen deficiency, it is suggested that the definition of androgen deficiency should be based on individual physiology, with the requirements of the individual at a particular stage of life setting the baseline against which any deficiency of androgens or androgen metabolites, either absolute or relative, is determined. This approach will affect the terminology, etiology, diagnosis, and treatment of androgen deficiency.

  20. Cellular MR Imaging

    Directory of Open Access Journals (Sweden)

    Michel Modo

    2005-07-01

    Full Text Available Cellular MR imaging is a young field that aims to visualize targeted cells in living organisms. In order to provide a different signal intensity of the targeted cell, they are either labeled with MR contrast agents in vivo or prelabeled in vitro. Either (ultrasmall superparamagnetic iron oxide [(USPIO] particles or (polymeric paramagnetic chelates can be used for this purpose. For in vivo cellular labeling, Gd3+- and Mn2+- chelates have mainly been used for targeted hepatobiliary imaging, and (USPIO-based cellular imaging has been focused on imaging of macrophage activity. Several of these magneto-pharmaceuticals have been FDA-approved or are in late-phase clinical trials. As for prelabeling of cells in vitro, a challenge has been to induce a sufficient uptake of contrast agents into nonphagocytic cells, without affecting normal cellular function. It appears that this issue has now largely been resolved, leading to an active research on monitoring the cellular biodistribution in vivo following transplantation or transfusion of these cells, including cell migration and trafficking. New applications of cellular MR imaging will be directed, for instance, towards our understanding of hematopoietic (immune cell trafficking and of novel guided (stem cell-based therapies aimed to be translated to the clinic in the future.

  1. Analysis of a large number of clinical studies for breast cancer radiotherapy: estimation of radiobiological parameters for treatment planning

    International Nuclear Information System (INIS)

    Guerrero, M; Li, X Allen

    2003-01-01

    Numerous studies of early-stage breast cancer treated with breast conserving surgery (BCS) and radiotherapy (RT) have been published in recent years. Both external beam radiotherapy (EBRT) and/or brachytherapy (BT) with different fractionation schemes are currently used. The present RT practice is largely based on empirical experience and it lacks a reliable modelling tool to compare different RT modalities or to design new treatment strategies. The purpose of this work is to derive a plausible set of radiobiological parameters that can be used for RT treatment planning. The derivation is based on existing clinical data and is consistent with the analysis of a large number of published clinical studies on early-stage breast cancer. A large number of published clinical studies on the treatment of early breast cancer with BCS plus RT (including whole breast EBRT with or without a boost to the tumour bed, whole breast EBRT alone, brachytherapy alone) and RT alone are compiled and analysed. The linear quadratic (LQ) model is used in the analysis. Three of these clinical studies are selected to derive a plausible set of LQ parameters. The potential doubling time is set a priori in the derivation according to in vitro measurements from the literature. The impact of considering lower or higher T pot is investigated. The effects of inhomogeneous dose distributions are considered using clinically representative dose volume histograms. The derived LQ parameters are used to compare a large number of clinical studies using different regimes (e.g., RT modality and/or different fractionation schemes with different prescribed dose) in order to validate their applicability. The values of the equivalent uniform dose (EUD) and biologically effective dose (BED) are used as a common metric to compare the biological effectiveness of each treatment regime. We have obtained a plausible set of radiobiological parameters for breast cancer. This set of parameters is consistent with in vitro

  2. The radiobiological response of the thyroid

    International Nuclear Information System (INIS)

    O'Connor, M.K.; Malone, J.F.; Moriarty, M.; Cullen, M.J.

    1980-01-01

    The response of sheep thyroid cells in culture to single doses of X or γ rays is described. In the absence of cellular proliferation the cells were unusually radioresistant, showing little sign of interphase death at doses up to 9 krad. The follicular morphology characteristic of thyroid cells in vivo was also very radioresistant. Iodide trapping was reduced to 50% of the control value by doses of the order of 2 krad. When proliferation was induced the cells could be assayed for post-irradiation survival using a clonogenic endpoint. The survival curves were sigmoid with a Do of 410 rad and a very low extrapolation number. (author)

  3. Programmable cellular arrays. Faults testing and correcting in cellular arrays

    International Nuclear Information System (INIS)

    Cercel, L.

    1978-03-01

    A review of some recent researches about programmable cellular arrays in computing and digital processing of information systems is presented, and includes both combinational and sequential arrays, with full arbitrary behaviour, or which can realize better implementations of specialized blocks as: arithmetic units, counters, comparators, control systems, memory blocks, etc. Also, the paper presents applications of cellular arrays in microprogramming, in implementing of a specialized computer for matrix operations, in modeling of universal computing systems. The last section deals with problems of fault testing and correcting in cellular arrays. (author)

  4. Radiobiological waste treatment-ashing treatment and immobilization with cement

    Energy Technology Data Exchange (ETDEWEB)

    Shengtao, Feng; Li, Gong; Li, Cheng; Benli, Wang; Lihong, Wang [China Inst. for Radiation Protection, Taiyuan, Shanxi (China)

    1997-02-01

    This report describes the results of the study on the treatment of radioactive biological waste in the China Institute for Radiation Protection (CIRP). The possibility of radiobiological waste treatment was investigated by using a RAF-3 type rapid ashing apparatus together with the immobilization of the resulted ash. This rapid ashing apparatus, developed by CIRP, is usually used for pretreatment of samples prior to chemical analysis and physical measurements. The results show that it can ash 3 kg of animal carcasses a batch, the ashing time is 5-7 h and the ash content is less than 4 wt%. The ashing temperature not exceeding 450 deg. C was used without any risk of high losses of radionuclides. The ash from the rapid ashing apparatus was demonstrated to be immobilized with ordinary silicate cement. The optimum cement/ash/water formulation of the cemented waste form was 35 {+-} 5 wt% cement, 29 {+-} 2 wt% water, and 36 {+-} 6 wt% ash. The performance of the waste form was in compliance with the technical requirements except for impact resistance. Mixing additives in immobilization formulations can improve the performance of the cemented ash waste form. The additives chosen were DH{sub 4A} flow promoter as a cement additive and vermiculite or zeolite as a supplement. The recommended formulation, i.e. an improved formulation of the cemented ash waste form is that additives DH{sub 4A} flow promoter and vermiculite (or zeolite) are added on the ground of optimum cement/ash/water formulation of the cemented waste form, the dosage of water, DH{sub 4A} and vermiculite (or zeolite) is 70 wt%, 0.5 wt% and {<=} 5 wt% of the cement dosage, respectively. The cemented ash waste forms obtained meet all the requirements for disposal. (author). 12 refs, 7 figs, 13 tabs.

  5. Radiobiological waste treatment-ashing treatment and immobilization with cement

    International Nuclear Information System (INIS)

    Feng Shengtao; Gong Li; Cheng Li; Wang Benli; Wang Lihong

    1997-01-01

    This report describes the results of the study on the treatment of radioactive biological waste in the China Institute for Radiation Protection (CIRP). The possibility of radiobiological waste treatment was investigated by using a RAF-3 type rapid ashing apparatus together with the immobilization of the resulted ash. This rapid ashing apparatus, developed by CIRP, is usually used for pretreatment of samples prior to chemical analysis and physical measurements. The results show that it can ash 3 kg of animal carcasses a batch, the ashing time is 5-7 h and the ash content is less than 4 wt%. The ashing temperature not exceeding 450 deg. C was used without any risk of high losses of radionuclides. The ash from the rapid ashing apparatus was demonstrated to be immobilized with ordinary silicate cement. The optimum cement/ash/water formulation of the cemented waste form was 35 ± 5 wt% cement, 29 ± 2 wt% water, and 36 ± 6 wt% ash. The performance of the waste form was in compliance with the technical requirements except for impact resistance. Mixing additives in immobilization formulations can improve the performance of the cemented ash waste form. The additives chosen were DH 4A flow promoter as a cement additive and vermiculite or zeolite as a supplement. The recommended formulation, i.e. an improved formulation of the cemented ash waste form is that additives DH 4A flow promoter and vermiculite (or zeolite) are added on the ground of optimum cement/ash/water formulation of the cemented waste form, the dosage of water, DH 4A and vermiculite (or zeolite) is 70 wt%, 0.5 wt% and ≤ 5 wt% of the cement dosage, respectively. The cemented ash waste forms obtained meet all the requirements for disposal. (author). 12 refs, 7 figs, 13 tabs

  6. A cardiac electrical activity model based on a cellular automata system in comparison with neural network model.

    Science.gov (United States)

    Khan, Muhammad Sadiq Ali; Yousuf, Sidrah

    2016-03-01

    Cardiac Electrical Activity is commonly distributed into three dimensions of Cardiac Tissue (Myocardium) and evolves with duration of time. The indicator of heart diseases can occur randomly at any time of a day. Heart rate, conduction and each electrical activity during cardiac cycle should be monitor non-invasively for the assessment of "Action Potential" (regular) and "Arrhythmia" (irregular) rhythms. Many heart diseases can easily be examined through Automata model like Cellular Automata concepts. This paper deals with the different states of cardiac rhythms using cellular automata with the comparison of neural network also provides fast and highly effective stimulation for the contraction of cardiac muscles on the Atria in the result of genesis of electrical spark or wave. The specific formulated model named as "States of automaton Proposed Model for CEA (Cardiac Electrical Activity)" by using Cellular Automata Methodology is commonly shows the three states of cardiac tissues conduction phenomena (i) Resting (Relax and Excitable state), (ii) ARP (Excited but Absolutely refractory Phase i.e. Excited but not able to excite neighboring cells) (iii) RRP (Excited but Relatively Refractory Phase i.e. Excited and able to excite neighboring cells). The result indicates most efficient modeling with few burden of computation and it is Action Potential during the pumping of blood in cardiac cycle.

  7. A Computational Model of Cellular Response to Modulated Radiation Fields

    Energy Technology Data Exchange (ETDEWEB)

    McMahon, Stephen J., E-mail: stephen.mcmahon@qub.ac.uk [Centre for Cancer Research and Cell Biology, Queen' s University Belfast, Belfast, Northern Ireland (United Kingdom); Butterworth, Karl T. [Centre for Cancer Research and Cell Biology, Queen' s University Belfast, Belfast, Northern Ireland (United Kingdom); McGarry, Conor K. [Centre for Cancer Research and Cell Biology, Queen' s University Belfast, Belfast, Northern Ireland (United Kingdom); Radiotherapy Physics, Northern Ireland Cancer Centre, Belfast Health and Social Care Trust, Northern Ireland (United Kingdom); Trainor, Colman [Centre for Cancer Research and Cell Biology, Queen' s University Belfast, Belfast, Northern Ireland (United Kingdom); O' Sullivan, Joe M. [Centre for Cancer Research and Cell Biology, Queen' s University Belfast, Belfast, Northern Ireland (United Kingdom); Clinical Oncology, Northern Ireland Cancer Centre, Belfast Health and Social Care Trust, Belfast, Northern Ireland (United Kingdom); Hounsell, Alan R. [Centre for Cancer Research and Cell Biology, Queen' s University Belfast, Belfast, Northern Ireland (United Kingdom); Radiotherapy Physics, Northern Ireland Cancer Centre, Belfast Health and Social Care Trust, Northern Ireland (United Kingdom); Prise, Kevin M. [Centre for Cancer Research and Cell Biology, Queen' s University Belfast, Belfast, Northern Ireland (United Kingdom)

    2012-09-01

    Purpose: To develop a model to describe the response of cell populations to spatially modulated radiation exposures of relevance to advanced radiotherapies. Materials and Methods: A Monte Carlo model of cellular radiation response was developed. This model incorporated damage from both direct radiation and intercellular communication including bystander signaling. The predictions of this model were compared to previously measured survival curves for a normal human fibroblast line (AGO1522) and prostate tumor cells (DU145) exposed to spatially modulated fields. Results: The model was found to be able to accurately reproduce cell survival both in populations which were directly exposed to radiation and those which were outside the primary treatment field. The model predicts that the bystander effect makes a significant contribution to cell killing even in uniformly irradiated cells. The bystander effect contribution varies strongly with dose, falling from a high of 80% at low doses to 25% and 50% at 4 Gy for AGO1522 and DU145 cells, respectively. This was verified using the inducible nitric oxide synthase inhibitor aminoguanidine to inhibit the bystander effect in cells exposed to different doses, which showed significantly larger reductions in cell killing at lower doses. Conclusions: The model presented in this work accurately reproduces cell survival following modulated radiation exposures, both in and out of the primary treatment field, by incorporating a bystander component. In addition, the model suggests that the bystander effect is responsible for a significant portion of cell killing in uniformly irradiated cells, 50% and 70% at doses of 2 Gy in AGO1522 and DU145 cells, respectively. This description is a significant departure from accepted radiobiological models and may have a significant impact on optimization of treatment planning approaches if proven to be applicable in vivo.

  8. A Computational Model of Cellular Response to Modulated Radiation Fields

    International Nuclear Information System (INIS)

    McMahon, Stephen J.; Butterworth, Karl T.; McGarry, Conor K.; Trainor, Colman; O’Sullivan, Joe M.; Hounsell, Alan R.; Prise, Kevin M.

    2012-01-01

    Purpose: To develop a model to describe the response of cell populations to spatially modulated radiation exposures of relevance to advanced radiotherapies. Materials and Methods: A Monte Carlo model of cellular radiation response was developed. This model incorporated damage from both direct radiation and intercellular communication including bystander signaling. The predictions of this model were compared to previously measured survival curves for a normal human fibroblast line (AGO1522) and prostate tumor cells (DU145) exposed to spatially modulated fields. Results: The model was found to be able to accurately reproduce cell survival both in populations which were directly exposed to radiation and those which were outside the primary treatment field. The model predicts that the bystander effect makes a significant contribution to cell killing even in uniformly irradiated cells. The bystander effect contribution varies strongly with dose, falling from a high of 80% at low doses to 25% and 50% at 4 Gy for AGO1522 and DU145 cells, respectively. This was verified using the inducible nitric oxide synthase inhibitor aminoguanidine to inhibit the bystander effect in cells exposed to different doses, which showed significantly larger reductions in cell killing at lower doses. Conclusions: The model presented in this work accurately reproduces cell survival following modulated radiation exposures, both in and out of the primary treatment field, by incorporating a bystander component. In addition, the model suggests that the bystander effect is responsible for a significant portion of cell killing in uniformly irradiated cells, 50% and 70% at doses of 2 Gy in AGO1522 and DU145 cells, respectively. This description is a significant departure from accepted radiobiological models and may have a significant impact on optimization of treatment planning approaches if proven to be applicable in vivo.

  9. Immuno-pharmacodynamics for evaluating mechanism of action and developing immunotherapy combinations.

    Science.gov (United States)

    Parchment, Ralph E; Voth, Andrea Regier; Doroshow, James H; Berzofsky, Jay A

    2016-08-01

    Immunotherapy has become a major modality of cancer treatment, with multiple new classes of immunotherapeutics recently entering the clinic and obtaining market approval from regulatory agencies. While the promise of these therapies is great, so is the number of possible combinations not only with each other but also with small molecule therapeutics. Furthermore, the observation of unusual dose-response relationships suggests a critical dependency of drug effectiveness on the dosage regimen (dose and schedule). Clinical pharmacodynamic (PD) biomarkers will be useful endpoints for confirming drug mechanism of action, evaluating combination therapies for synergy or antagonism, and identifying optimal dosage regimens. In contrast to conventional PD in which drug action occurs entirely within a single target cell (ie, is self-contained within the malignant cell), immunotherapy involves a complex mechanism of action with sequential steps that propagate through multiple cell types, both normal and malignant. Its intercellular pharmacology begins with molecular target engagement either on an immune effector cell or a malignant cell, followed by stimulatory biochemical and biological signals in immune effector cells, and then finally ends with activation of cell death mechanisms in malignant cells lying within a certain distance from the activated effector cells (immune cell-tumor cell proximity). Evaluating such "trans-cellular pharmacology," in which different steps of drug action are distributed across multiple cell types, requires novel microscopy and image analysis tools capable of quantifying PD-biomarker responses, mapping the responses onto the cellular geography of the tumor using phenotypic biomarkers to identify specific cell types, and finally analyzing the spatial relationships between biomarkers in the context of each cell's biological role. We have termed this form of nearest neighbor image analysis of drug action "proximity PD microscopy," to indicate the

  10. Molecular processes in cellular arsenic metabolism

    International Nuclear Information System (INIS)

    Thomas, David J.

    2007-01-01

    Elucidating molecular processes that underlie accumulation, metabolism and binding of iAs and its methylated metabolites provides a basis for understanding the modes of action by which iAs acts as a toxin and a carcinogen. One approach to this problem is to construct a conceptual model that incorporates available information on molecular processes involved in the influx, metabolism, binding and efflux of arsenicals in cells. This conceptual model is initially conceived as a non-quantitative representation of critical molecular processes that can be used as a framework for experimental design and prediction. However, with refinement and incorporation of additional data, the conceptual model can be expressed in mathematical terms and should be useful for quantitative estimates of the kinetic and dynamic behavior of iAs and its methylated metabolites in cells. Development of a quantitative model will be facilitated by the availability of tools and techniques to manipulate molecular processes underlying transport of arsenicals across cell membranes or expression and activity of enzymes involved in methylation of arsenicals. This model of cellular metabolism might be integrated into more complex pharmacokinetic models for systemic metabolism of iAs and its methylated metabolites. It may also be useful in development of biologically based dose-response models describing the toxic and carcinogenic actions of arsenicals

  11. 47 CFR 22.970 - Unacceptable interference to part 90 non-cellular 800 MHz licensees from cellular radiotelephone...

    Science.gov (United States)

    2010-10-01

    ...-cellular 800 MHz licensees from cellular radiotelephone or part 90-800 MHz cellular systems. 22.970 Section... MOBILE SERVICES Cellular Radiotelephone Service § 22.970 Unacceptable interference to part 90 non-cellular 800 MHz licensees from cellular radiotelephone or part 90-800 MHz cellular systems. (a) Definition...

  12. Research and development program, fiscal year 1974

    Energy Technology Data Exchange (ETDEWEB)

    1972-04-01

    The biomedical program of the Laboratory of Nuclear Medicine and Radiation Biology for Fiscal Year 1974 is conducted within the scope of the following categories: Effects of Radiation of Living Organisms; Molecular and Cellular Radiobiology; Land and Fresh Water Environmental Sciences; Radiological and Health Physics and Instrumentation; and Nuclear Medical Research. (ACR)

  13. Suppression of cellular immunity in obstructive jaundice is caused by endotoxins: a study with germ-free rats

    NARCIS (Netherlands)

    Greve, J. W.; Gouma, D. J.; Soeters, P. B.; Buurman, W. A.

    1990-01-01

    The increased susceptibility to infections after surgery in jaundiced patients is considered to be caused by an impairment of cellular immunity and/or nutritional status. Endotoxins are suggested to play a role in the pathogenesis. However, the mechanism of action is unknown. Germ-free rats were

  14. Probabilistic cellular automata: Some statistical mechanical considerations

    International Nuclear Information System (INIS)

    Lebowitz, J.L.; Maes, C.; Speer, E.R.

    1990-01-01

    Spin systems evolving in continuous or discrete time under the action of stochastic dynamics are used to model phenomena as diverse as the structure of alloys and the functioning of neural networks. While in some cases the dynamics are secondary, designed to produce a specific stationary measure whose properties one is interested in studying, there are other cases in which the only available information is the dynamical rule. Prime examples of the former are computer simulations, via Glauber dynamics, of equilibrium Gibbs measures with a specified interaction potential. Examples of the latter include various types of majority rule dynamics used as models for pattern recognition and for error-tolerant computations. The present note discusses ways in which techniques found useful in equilibrium statistical mechanics can be applied to a particular class of models of the latter types. These are cellular automata with noise: systems in which the spins are updated stochastically at integer times, simultaneously at all sites of some regular lattice. These models were first investigated in detail in the Soviet literature of the late sixties and early seventies. They are now generally referred to as Stochastic or Probabilistic Cellular Automata (PCA), and may be considered to include deterministic automata (CA) as special limits. 16 refs., 3 figs

  15. Cellular reprogramming through mitogen-activated protein kinases

    Directory of Open Access Journals (Sweden)

    Justin eLee

    2015-10-01

    Full Text Available Mitogen-activated protein kinase (MAPK cascades are conserved eukaryote signaling modules where MAPKs, as the final kinases in the cascade, phosphorylate protein substrates to regulate cellular processes. While some progress in the identification of MAPK substrates has been made in plants, the knowledge on the spectrum of substrates and their mechanistic action is still fragmentary. In this focused review, we discuss the biological implications of the data in our original paper (Sustained mitogen-activated protein kinase activation reprograms defense metabolism and phosphoprotein profile in Arabidopsis thaliana; Frontiers in Plant Science 5: 554 in the context of related research. In our work, we mimicked in vivo activation of two stress-activated MAPKs, MPK3 and MPK6, through transgenic manipulation of Arabidopsis thaliana and used phosphoproteomics analysis to identify potential novel MAPK substrates. Here, we plotted the identified putative MAPK substrates (and downstream phosphoproteins as a global protein clustering network. Based on a highly stringent selection confidence level, the core networks highlighted a MAPK-induced cellular reprogramming at multiple levels of gene and protein expression – including transcriptional, post-transcriptional, translational, post-translational (such as protein modification, folding and degradation steps, and also protein re-compartmentalization. Additionally, the increase in putative substrates/phosphoproteins of energy metabolism and various secondary metabolite biosynthesis pathways coincides with the observed accumulation of defense antimicrobial substances as detected by metabolome analysis. Furthermore, detection of protein networks in phospholipid or redox elements suggests activation of downstream signaling events. Taken in context with other studies, MAPKs are key regulators that reprogram cellular events to orchestrate defense signaling in eukaryotes.

  16. Heterogeneous cellular networks

    CERN Document Server

    Hu, Rose Qingyang

    2013-01-01

    A timely publication providing coverage of radio resource management, mobility management and standardization in heterogeneous cellular networks The topic of heterogeneous cellular networks has gained momentum in industry and the research community, attracting the attention of standardization bodies such as 3GPP LTE and IEEE 802.16j, whose objectives are looking into increasing the capacity and coverage of the cellular networks. This book focuses on recent progresses,  covering the related topics including scenarios of heterogeneous network deployment, interference management i

  17. Cellular pharmacodynamics of the cytotoxic guanidino-containing drug CHS 828. Comparison with methylglyoxal-bis(guanylhydrazone).

    Science.gov (United States)

    Ekelund, S; Sjöholm, A; Nygren, P; Binderup, L; Larsson, R

    2001-04-20

    N-(6-(4-chlorophenoxy)hexyl)-N'-cyano-N"-4-pyridylguanidine (CHS 828) is a new guanidino-containing compound with antitumoral activity both in vitro and in vivo. Its activity profile differs from those of standard cytotoxic drugs but the mechanism of action is not yet fully understood. CHS 828 is presently in early phase I and II clinical trials. In the present study, the pharmacodynamic effects at the cellular level of CHS 828 was compared to another compound containing two guanidino groups, methylglyoxal-bis(guanylhydrazone) (MGBG). MGBG is known to inhibit the synthesis of polyamines, which are important in, e.g., proliferation and macromolecular synthesis. The concentration-response relationship of CHS 828 closely resembled that of MGBG and the drugs were similar with respect to inhibition of DNA and protein synthesis. On the other hand, CHS 828 induced a significant increase in cellular metabolism while MGBG did not. The cytotoxic effect of MGBG was reversed by the addition of exogenous polyamines, while that of CHS 828 was unaffected. Unlike MGBG, there was also no effect of CHS 828 on the levels of decarboxylating enzymes in the polyamine biosynthesis. In conclusion, CHS 828 does not appear to share any major mechanisms of action with the polyamine synthesis inhibitor MGBG. Further studies will be required to define the exact mechanism of action of CHS 828.

  18. Dosimetry and radiobiology at the new RA-3 reactor boron neutron capture therapy (BNCT) facility: Application to the treatment of experimental oral cancer

    Energy Technology Data Exchange (ETDEWEB)

    Pozzi, E. [Research and Production Reactors, National Atomic Energy Commission, Ezeiza Atomic Center (Argentina); Department of Radiobiology, National Atomic Energy Commission, Constituyentes Atomic Center (Argentina)], E-mail: epozzi@cnea.gov.ar; Nigg, D.W. [Idaho National Laboratory, Idaho Falls (United States); Miller, M.; Thorp, S.I. [Instrumentation and Control Department, National Atomic Energy Commission, Ezeiza Atomic Center (Argentina); Heber, E.M. [Department of Radiobiology, National Atomic Energy Commission, Constituyentes Atomic Center (Argentina); Zarza, L.; Estryk, G. [Research and Production Reactors, National Atomic Energy Commission, Ezeiza Atomic Center (Argentina); Monti Hughes, A.; Molinari, A.J.; Garabalino, M. [Department of Radiobiology, National Atomic Energy Commission, Constituyentes Atomic Center (Argentina); Itoiz, M.E. [Department of Radiobiology, National Atomic Energy Commission, Constituyentes Atomic Center (Argentina); Department of Oral Pathology, Faculty of Dentistry, University of Buenos Aires (Argentina); Aromando, R.F. [Department of Oral Pathology, Faculty of Dentistry, University of Buenos Aires (Argentina); Quintana, J. [Research and Production Reactors, National Atomic Energy Commission, Ezeiza Atomic Center (Argentina); Trivillin, V.A.; Schwint, A.E. [Department of Radiobiology, National Atomic Energy Commission, Constituyentes Atomic Center (Argentina)

    2009-07-15

    The National Atomic Energy Commission of Argentina (CNEA) constructed a novel thermal neutron source for use in boron neutron capture therapy (BNCT) applications at the RA-3 research reactor facility located in Buenos Aires. The aim of the present study was to perform a dosimetric characterization of the facility and undertake radiobiological studies of BNCT in an experimental model of oral cancer in the hamster cheek pouch. The free-field thermal flux was 7.1x10{sup 9} n cm{sup -2} s{sup -1} and the fast neutron flux was 2.5x10{sup 6} n cm{sup -2} s{sup -1}, indicating a very well-thermalized neutron field with negligible fast neutron dose. For radiobiological studies it was necessary to shield the body of the hamster from the neutron flux while exposing the everted cheek pouch bearing the tumors. To that end we developed a lithium (enriched to 95% in {sup 6}Li) carbonate enclosure. Groups of tumor-bearing hamsters were submitted to BPA-BNCT, GB-10-BNCT, (GB-10+BPA)-BNCT or beam only treatments. Normal (non-cancerized) hamsters were treated similarly to evaluate normal tissue radiotoxicity. The total physical dose delivered to tumor with the BNCT treatments ranged from 6 to 8.5 Gy. Tumor control at 30 days ranged from 73% to 85%, with no normal tissue radiotoxicity. Significant but reversible mucositis in precancerous tissue surrounding tumors was associated to BPA-BNCT. The therapeutic success of different BNCT protocols in treating experimental oral cancer at this novel facility was unequivocally demonstrated.

  19. Dosimetry and radiobiology at the new RA-3 reactor boron neutron capture therapy (BNCT) facility: Application to the treatment of experimental oral cancer

    International Nuclear Information System (INIS)

    Pozzi, E.; Nigg, D.W.; Miller, M.; Thorp, S.I.; Heber, E.M.; Zarza, L.; Estryk, G.; Monti Hughes, A.; Molinari, A.J.; Garabalino, M.; Itoiz, M.E.; Aromando, R.F.; Quintana, J.; Trivillin, V.A.; Schwint, A.E.

    2009-01-01

    The National Atomic Energy Commission of Argentina (CNEA) constructed a novel thermal neutron source for use in boron neutron capture therapy (BNCT) applications at the RA-3 research reactor facility located in Buenos Aires. The aim of the present study was to perform a dosimetric characterization of the facility and undertake radiobiological studies of BNCT in an experimental model of oral cancer in the hamster cheek pouch. The free-field thermal flux was 7.1x10 9 n cm -2 s -1 and the fast neutron flux was 2.5x10 6 n cm -2 s -1 , indicating a very well-thermalized neutron field with negligible fast neutron dose. For radiobiological studies it was necessary to shield the body of the hamster from the neutron flux while exposing the everted cheek pouch bearing the tumors. To that end we developed a lithium (enriched to 95% in 6 Li) carbonate enclosure. Groups of tumor-bearing hamsters were submitted to BPA-BNCT, GB-10-BNCT, (GB-10+BPA)-BNCT or beam only treatments. Normal (non-cancerized) hamsters were treated similarly to evaluate normal tissue radiotoxicity. The total physical dose delivered to tumor with the BNCT treatments ranged from 6 to 8.5 Gy. Tumor control at 30 days ranged from 73% to 85%, with no normal tissue radiotoxicity. Significant but reversible mucositis in precancerous tissue surrounding tumors was associated to BPA-BNCT. The therapeutic success of different BNCT protocols in treating experimental oral cancer at this novel facility was unequivocally demonstrated.

  20. Surface deformation during an action potential in pearled cells

    Science.gov (United States)

    Mussel, Matan; Fillafer, Christian; Ben-Porath, Gal; Schneider, Matthias F.

    2017-11-01

    Electric pulses in biological cells (action potentials) have been reported to be accompanied by a propagating cell-surface deformation with a nanoscale amplitude. Typically, this cell surface is covered by external layers of polymer material (extracellular matrix, cell wall material, etc.). It was recently demonstrated in excitable plant cells (Chara braunii) that the rigid external layer (cell wall) hinders the underlying deformation. When the cell membrane was separated from the cell wall by osmosis, a mechanical deformation, in the micrometer range, was observed upon excitation of the cell. The underlying mechanism of this mechanical pulse has, to date, remained elusive. Herein we report that Chara cells can undergo a pearling instability, and when the pearled fragments were excited even larger and more regular cell shape changes were observed (˜10 -100 μ m in amplitude). These transient cellular deformations were captured by a curvature model that is based on three parameters: surface tension, bending rigidity, and pressure difference across the surface. In this paper these parameters are extracted by curve-fitting to the experimental cellular shapes at rest and during excitation. This is a necessary step to identify the mechanical parameters that change during an action potential.

  1. 47 CFR 22.909 - Cellular markets.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 2 2010-10-01 2010-10-01 false Cellular markets. 22.909 Section 22.909... Cellular Radiotelephone Service § 22.909 Cellular markets. Cellular markets are standard geographic areas used by the FCC for administrative convenience in the licensing of cellular systems. Cellular markets...

  2. Screening action potentials: The power of light

    Directory of Open Access Journals (Sweden)

    Lars eKaestner

    2011-07-01

    Full Text Available Action potentials reflect the concerted activity of all electrogenic constituents in the plasma membrane during the excitation of a cell. Therefore, the action potential is an integrated readout and a promising parameter to detect electrophysiological failures or modifications thereof in diagnosis as well as in drug screens. Cellular action potentials can be recorded by optical approaches. To fulfill the pre-requirements to scale up for e.g. pharmacological screens the following preparatory work has to be provided: (i model cells under investigation need to represent target cells in the best possible manner; (ii optical sensors that can be either small molecule dyes or genetically encoded potential probes need to provide a reliable readout with minimal interaction with the naive behavior of the cells and (iii devices need to be capable to stimulate the cells, read out the signals with the appropriate speed as well as provide the capacity for a sufficient throughput. Here we discuss several scenarios for all three categories in the field of cardiac physiology and pharmacology and provide a perspective to use the power of light in screening cardiac action potentials.

  3. Basic principles of molecular effects of irradiation.

    Science.gov (United States)

    Selzer, Edgar; Hebar, Alexandra

    2012-02-01

    In order to understand the consequences of radiation a thorough understanding of the radiobiological mechanisms of the molecular up to the clinical level is of importance. Radiobiology therefore combines the basic principles of physics as well as biology and medicine and is concerned with the action of radiation from the subcellular level up to the living organism. Topics of interest and relevance are covered in much more broadness as is possible in the short following article in the literature to which the interested reader is referred to. Classical books in this field were written by Steel et al. (1989) as well as by Hall (1994). Topics usually covered by radiobiological reviews are the classification of different types of radiation, cell cycle dependency of radiation effects, types of radiation damage and cell death, dose response curves, measurement of radiation damage, the oxygen effect, relative biological effectiveness, the influence of dose rate, and several other important research areas. This short overview will concentrate on a subset of radiobiological topics of high importance and relative novelty.

  4. Abstracts of papers of international scientific conference 'Fundamental and applied aspects of radiobiology: Biological effects of low doses and radioactive contamination of environment (Radioecological and medical biological consequences of the Chernobyl NPP accident)'

    International Nuclear Information System (INIS)

    Konoplya, E.F.; Astakhov, A.I.; Bogdevich, I.M.; Borisevich, N.Ya.; Zubovich, V.K.; Knat'ko, V.A.; Lobanok, L.M.; Matsko, V.P.; Mrochek, A.G.

    1998-05-01

    The results of research works executed in Belarus, as well as in Ukraine and Russia, on various aspects of the Chernobyl problematic are given: radiation medicine and risks, radiobiological effects and their forecasting, radioecology and agricultural radiology, decontamination and radioactive wastes management, socio economic and psychological problems caused by the Chernobyl NPP accident

  5. Brachytherapy optimization using radiobiological-based planning for high dose rate and permanent implants for prostate cancer treatment

    Science.gov (United States)

    Seeley, Kaelyn; Cunha, J. Adam; Hong, Tae Min

    2017-01-01

    We discuss an improvement in brachytherapy--a prostate cancer treatment method that directly places radioactive seeds inside target cancerous regions--by optimizing the current standard for delivering dose. Currently, the seeds' spatiotemporal placement is determined by optimizing the dose based on a set of physical, user-defined constraints. One particular approach is the ``inverse planning'' algorithms that allow for tightly fit isodose lines around the target volumes in order to reduce dose to the patient's organs at risk. However, these dose distributions are typically computed assuming the same biological response to radiation for different types of tissues. In our work, we consider radiobiological parameters to account for the differences in the individual sensitivities and responses to radiation for tissues surrounding the target. Among the benefits are a more accurate toxicity rate and more coverage to target regions for planning high-dose-rate treatments as well as permanent implants.

  6. Low LET protons focused to submicrometer shows enhanced radiobiological effectiveness

    International Nuclear Information System (INIS)

    Schmid, T E; Zlobinskaya, O; Michalski, D; Molls, M; Multhoff, G; Greubel, C; Hable, V; Girst, S; Siebenwirth, C; Dollinger, G; Schmid, E

    2012-01-01

    This study shows that enhanced radiobiological effectiveness (RBE) values can be generated focusing low linear energy transfer (LET) radiation and thus changing the microdose distribution. 20 MeV protons (LET = 2.65 keV µm −1 ) are focused to submicrometer diameter at the ion microprobe superconducting nanoprobe for applied nuclear (Kern) physics experiments of the Munich tandem accelerator. The RBE values, as determined by measuring micronuclei (RBE MN = 1.48 ± 0.07) and dicentrics (RBE D = 1.92 ± 0.15), in human–hamster hybrid (A L ) cells are significantly higher when 117 protons were focused to a submicrometer irradiation field within a 5.4 × 5.4 µm 2 matrix compared to quasi homogeneous in a 1 × 1 µm 2 matrix applied protons (RBE MN = 1.28 ± 0.07; RBE D = 1.41 ± 0.14) at the same average dose of 1.7 Gy. The RBE values are normalized to standard 70 kV (dicentrics) or 200 kV (micronuclei) x-ray irradiation. The 117 protons applied per point deposit the same amount of energy like a 12 C ion with 55 MeV total energy (4.48 MeV u −1 ). The enhancements are about half of that obtained for 12 C ions (RBE MN = 2.20 ± 0.06 and RBE D = 3.21 ± 0.10) and they are attributed to intertrack interactions of the induced damages. The measured RBE values show differences from predictions of the local effect model (LEM III) that is used to calculate RBE values for irradiation plans to treat tumors with high LET particles. (paper)

  7. Radiobiologically based assessments of the net costs of fractionated radiotherapy

    International Nuclear Information System (INIS)

    Dale, Roger G.; Jones, Bleddyn

    1996-01-01

    Purpose: To examine how the long-term costs of radiation therapy may be influenced by modifications to fractionation schemes, and how any improvements in tumor control might, in principle, be translated into a potential cost saving for the responsible healthcare organization. Methods and Materials: Standard radiobiological modeling based on the linear-quadratic (LQ) model is combined with financial parameters relating to the estimated costs of different aspects of radiotherapy treatment delivery. The cost model includes provision for the long-term costs of treatment failure and enables the extra costs of near optimal radiotherapy to be balanced against suboptimal alternatives, which are more likely to be associated with further radiotherapy, salvage surgery, and continuing care. Results: A number of caveats are essential in presenting a model such as this for the first time, and these are clearly stated. However, a recurring observation is that, in terms of the whole cost of supporting a patient from first radiotherapy treatment onwards, high quality radiotherapy (i.e., based on individual patterns of fractionation that are near optimal for particular subpopulations of tumor) will frequently be associated with the lowest global cost. Conclusions: This work adds weight to the case for identifying fast and accurate predictive assay techniques, and supports the argument that suboptimal radiotherapy is usually more costly in the long term. Although the article looks only at the cost-benefit consequences of altered patterns of fractionation, the method will, in principle, have application to other changes in the way radiotherapy can be performed, e.g., to examining the cost-benefit aspects of tumor dose escalation as a consequence of using advanced conformal treatment planning

  8. AFRRI (Armed Forces Radiobiology Research Institute) reports, April, May, June 1987. Technical report

    Energy Technology Data Exchange (ETDEWEB)

    1987-07-01

    This document is a collection of reprinted technical reports. Partial contents include: Effect of ionizing radiation on prostaglandins and gastric secretion in rhesus monkeys; Characterization of rat prothymocyte with monoclonal antibodies recognizing rat lymphocyte membrane antigenic determinants; Effects of subdiaphragmatic vagotomy on the acquisition of a radiation-induced condition taste aversion; Ethanol-induced taste aversions; Lack of involvement of acetaldehyde and the area postrema; Dose and time relationships of the radioprotector WR-2721 on locomotor activity in mice; Purification and analysis of rat hematopoietic stem cells by flow cytometry, Plasma histamine and catecholamine levels during hypotension induced by morphine and compound 48/80; Effects of ionizing radiation on hippocampal excitability, Tumor necrosis factor/cachectin is a less-potent inducer of serum amyloid A synthesis than interleukin 1, Protection of mice against fission-neutron irradiation by WR-2721 or WR-151327, Induction of colony-stimulating factor in vivo by recombinant interleukin 1 a and recombinant tumor necrosis factor alpha; 16,16-Dimethyl prostaglandin E2 increases survival in mice following irradiation, Selenium pretreatment enhances the radioprotective effect and reduces the lethal toxicity of WR-2721; Rat phantom depth dose studies in electron, x-ray, gamma-ray, and reactor-radiation fields; Wall attenuation and scatter characteristics of ionization chambers at Armed Forces Radiobiology Research Institute.

  9. Radiobiological characterization of different energy-photon beams used in radiotherapy from linear accelerator

    International Nuclear Information System (INIS)

    Elata, A.; Hassan, A. M. E.; Ali, E.; Calzolari, P.; Bettega, D.

    2009-02-01

    The main objective of this study was to perform a radiobiological characterization of different energy photon beams (6 MV and 15 MV) from linear accelerator used in radiotherapy, and comparison of different treatment modalities, with special regard to late effects of radiation. Using two end points, cell survival and micronucleus induction, in the biological system (Chines hamster V79 cell line). Chromosomes number was counted and found to be 22 chromosomes per cell. Cells were kept in confluent growth for two days and then exposed to two photon beams and immediately after irradiation were counted and re seeded in different numbered for each dose. For evaluation of surviving fraction samples were incubated at 37o C for 6 days, five samples were counted for each dose. At the same time three samples were seeded for the micronuclei frequency and incubated at 37o C after 24 hours cytochalasin-B was added to block cells in cytokinesis. The survival curve showed similar curves for the two beams and decreased with dose. The micronuclei frequency was positively correlated with dose and the energy of the photon. This indicates the presence of low dose of photoneutrons produced by using high energy photon beams. (Author)

  10. The Nasa space radiation school, an excellent training in radiobiology and space radiation protection

    International Nuclear Information System (INIS)

    Vogin, G.

    2009-01-01

    The astronauts have to spend more time in space and the colonization of the moon and Mars are in the cross hairs of international agencies. The cosmic radiation from which we are protected on ground by atmosphere and by the terrestrial magnetosphere (.4 mSv/year according to Who) become really threatening since 20 km altitude, delivering an average radiation dose of a therapeutic kind to astronauts with peaks related to solar events. It is composed in majority of hadrons: protons (85%) and heavy ions (13%), but also photons (2%) of high energy (GeV/n)). the incurred risks are multiple: early ones(cataract, central nervous system damages, whole body irradiation) but especially delayed ones (carcinogenesis). The astronauts radiation protection turns poor and the rate of death risk by cancer returning from a mission on Mars has been estimated at 5%. The Nasa created in 2004 a summer school aiming to awareness young researchers to the space radiobiology specificities. Areas concerned as follow: radioinduced DNA damage and repair, cell cycle, apoptosis, bystander effect, genome instability, neuro degeneration, delayed effects and carcinogenesis in relation with radiation exposure. (N.C.)

  11. Conjunct action of gamma radiation and casiopeinas in two cellular types; Accion conjunta de radiacion gamma y casiopeinas en dos tipos celulares

    Energy Technology Data Exchange (ETDEWEB)

    Ramos V, N.I

    2006-07-01

    In Mexico the cancer occupies the second place in the causes of death and although already there are diverse useful treatments to attack this suffering, the search of new pharmaceuticals that present positive effect in the treatment of the cancer there is taken to the development of a group of substances called Casiopeinas. Its are coordination compounds constituted by a central atom of copper (Cu II) joined to organic ligands, with general condensed formula [Cu (NN)(ON)]NO{sub 3}, or [Cu(NN)(OO)]NO{sub 3}. Its present different cytotoxicity levels, as well as in vitro antineoplastic activity in diverse tissues derived of tumors. Even its ignore the mechanisms of it action, but one of them, it could be by generation of reactive species of oxygen (ERO), mediated by the metallic center that contain. Thinking of this possibility was carried out in vitro experiments, exposing lymphocytes or HeLa cells, to ionizing radiation, at two casiopeinas (Casiopeina llgly and the Casiopeina Ill-e-a) or the combination of both agents, in order to determine if the antineoplastic capacity of both types of treatments increase in conjunct action. To determine it its were carried out cytotoxicity tests by means of the differential dyeing of fluorescein diacetate and etidio bromide, in these the cells alive fluorescein in green color while the dead ones only the nucleus of red tinged. The genotoxicity was evaluated by means of the comet essay. The results hurtled that as much the casiopeinas as the radiation by separate don't present difference among both cellular types, probably due to the used method that only quantifies the damages at the moment and not to long term. And according to those treatments on the whole only to the concentrations and the doses more high it favors the additive effect due to an overproduction of free radicals that not can be neutralized. According to the genotoxicity, only proven for the radiation indicates that the HeLa cells presents a major number of

  12. Conjunct action of gamma radiation and casiopeinas in two cellular types; Accion conjunta de radiacion gamma y casiopeinas en dos tipos celulares

    Energy Technology Data Exchange (ETDEWEB)

    Ramos V, N I

    2006-07-01

    In Mexico the cancer occupies the second place in the causes of death and although already there are diverse useful treatments to attack this suffering, the search of new pharmaceuticals that present positive effect in the treatment of the cancer there is taken to the development of a group of substances called Casiopeinas. Its are coordination compounds constituted by a central atom of copper (Cu II) joined to organic ligands, with general condensed formula [Cu (NN)(ON)]NO{sub 3}, or [Cu(NN)(OO)]NO{sub 3}. Its present different cytotoxicity levels, as well as in vitro antineoplastic activity in diverse tissues derived of tumors. Even its ignore the mechanisms of it action, but one of them, it could be by generation of reactive species of oxygen (ERO), mediated by the metallic center that contain. Thinking of this possibility was carried out in vitro experiments, exposing lymphocytes or HeLa cells, to ionizing radiation, at two casiopeinas (Casiopeina llgly and the Casiopeina Ill-e-a) or the combination of both agents, in order to determine if the antineoplastic capacity of both types of treatments increase in conjunct action. To determine it its were carried out cytotoxicity tests by means of the differential dyeing of fluorescein diacetate and etidio bromide, in these the cells alive fluorescein in green color while the dead ones only the nucleus of red tinged. The genotoxicity was evaluated by means of the comet essay. The results hurtled that as much the casiopeinas as the radiation by separate don't present difference among both cellular types, probably due to the used method that only quantifies the damages at the moment and not to long term. And according to those treatments on the whole only to the concentrations and the doses more high it favors the additive effect due to an overproduction of free radicals that not can be neutralized. According to the genotoxicity, only proven for the radiation indicates that the HeLa cells presents a major number of cells

  13. Biomechanics of cellular solids.

    Science.gov (United States)

    Gibson, Lorna J

    2005-03-01

    Materials with a cellular structure are widespread in nature and include wood, cork, plant parenchyma and trabecular bone. Natural cellular materials are often mechanically efficient: the honeycomb-like microstructure of wood, for instance, gives it an exceptionally high performance index for resisting bending and buckling. Here we review the mechanics of a wide range of natural cellular materials and examine their role in lightweight natural sandwich structures (e.g. iris leaves) and natural tubular structures (e.g. plant stems or animal quills). We also describe two examples of engineered biomaterials with a cellular structure, designed to replace or regenerate tissue in the body.

  14. Epidemiological and radio-biological studies in high background radiation areas of Kerala coast: implications in radiation protection science and human health

    International Nuclear Information System (INIS)

    Das, Birajalaxmi

    2018-01-01

    Till date, Linear No Threshold hypothesis (LNT) is well accepted in radiation protection science in spite of its limitations. However, dose response studies using multiple biological end points from high-background radiation areas have challenged the linearity. Radio-biological and epidemiological studies from high level natural radiation areas of Kerala coast showed non-linearity as well as efficient repair of DNA damage in HLNRA indicating that dose limits for public exposure needs to be revisited which may have implications in radiation protection science, human health and low dose radiation biology. However, further studies using high throughput approach is required to identify chronic radiation signatures in human population exposed to elevated level of natural background radiation

  15. Cellular Reflectarray Antenna

    Science.gov (United States)

    Romanofsky, Robert R.

    2010-01-01

    The cellular reflectarray antenna is intended to replace conventional parabolic reflectors that must be physically aligned with a particular satellite in geostationary orbit. These arrays are designed for specified geographical locations, defined by latitude and longitude, each called a "cell." A particular cell occupies nominally 1,500 square miles (3,885 sq. km), but this varies according to latitude and longitude. The cellular reflectarray antenna designed for a particular cell is simply positioned to align with magnetic North, and the antenna surface is level (parallel to the ground). A given cellular reflectarray antenna will not operate in any other cell.

  16. Measuring in vitro cellular uptake of nanoparticles by transmission electron microscopy

    International Nuclear Information System (INIS)

    Brown, A P; Brydson, R M D; Hondow, N S

    2014-01-01

    Biomedical application of engineered nanoparticles (NPs) is a growing area of research and development. Uncertainty remains as to the mode of action of many NP types and TEM is a tool capable of addressing this if used in conjunction with standard cellular response assays. We will demonstrate imaging of thin sections of fixed, plastic embedded cells by analytical TEM to identify: superparamagnetic iron oxide NP translocation into cell compartments such as endosomes; amorphous silica NP penetration through a cell membrane without membrane encapsulation and zinc oxide NP degradation in cell compartments. We will then discuss how the in vitro cellular responses to a dose of NPs exposed to cell lines can be correlated to the internalized dose per cell section noting however that quantification of the latter requires random sampling procedures or correlation to higher throughout techniques to measure a population of whole cells. Similarly, analytical TEM measures of NP degradation within intracellular compartments will require a more appropriate sample preparation such as cryo-fixation

  17. Linearizable cellular automata

    International Nuclear Information System (INIS)

    Nobe, Atsushi; Yura, Fumitaka

    2007-01-01

    The initial value problem for a class of reversible elementary cellular automata with periodic boundaries is reduced to an initial-boundary value problem for a class of linear systems on a finite commutative ring Z 2 . Moreover, a family of such linearizable cellular automata is given

  18. Electromagnetic cellular interactions.

    Science.gov (United States)

    Cifra, Michal; Fields, Jeremy Z; Farhadi, Ashkan

    2011-05-01

    Chemical and electrical interaction within and between cells is well established. Just the opposite is true about cellular interactions via other physical fields. The most probable candidate for an other form of cellular interaction is the electromagnetic field. We review theories and experiments on how cells can generate and detect electromagnetic fields generally, and if the cell-generated electromagnetic field can mediate cellular interactions. We do not limit here ourselves to specialized electro-excitable cells. Rather we describe physical processes that are of a more general nature and probably present in almost every type of living cell. The spectral range included is broad; from kHz to the visible part of the electromagnetic spectrum. We show that there is a rather large number of theories on how cells can generate and detect electromagnetic fields and discuss experimental evidence on electromagnetic cellular interactions in the modern scientific literature. Although small, it is continuously accumulating. Copyright © 2010 Elsevier Ltd. All rights reserved.

  19. Microdosimetric investigation of a fast neutron radiobiology facility utilising the d(4)-9Be reaction.

    Science.gov (United States)

    Waker, A J; Maughan, R L

    1986-11-01

    For fast neutron therapy and radiobiology beams, knowledge of the primary neutron spectrum is the most fundamental requirement for the definition of radiation quality. However, microdosimetric measurements in the form of single-event spectra not only complement the primary neutron spectrum as a statement of radiation quality but also provide a sensitive method of detecting changes in the radiation field in situations where it is no longer possible to have precise knowledge of the primary neutron spectrum, for example after collimator changes and in positions where the radiation field consists of a large scattered component. For the various collimator arrangements employed at the Gray Laboratory facility small perturbations of the radiation field are observed which can be related to a softening of the primary neutron spectrum with increasing field size of the collimator. Gamma fraction determinations are in very good agreement with measurements employing the dual chamber technique and also show small changes with collimator field size giving rise to gamma components ranging from 0.09 to 0.12, the higher values being measured for the larger field sizes. Quality changes represented by the shape of the measured event-size spectra and the derived microdosimetric parameters were greatest for off axis and phantom measurements. With increasing depth in water, yD was found to decrease from 47.3 keV micron-1 at 5 cm to 35.6 keV micron-1 at 15 cm depth, and the gamma fraction was found to increase from 0.23 to 0.40. Although there is no generally accepted and agreed method of relating microdosimetric information to biological effectiveness, the dual radiation theory in its original form (Kellerer and Rossi 1972) has been shown to be a very useful model for the assessment of the biological effectiveness of fast neutrons (Kellerer et al 1976). The microdosimetric parameter which is used in the dual radiation model is the dose mean specific energy corrected for saturation zeta

  20. Radiobiology of hypofractionated stereotactic radiotherapy: what are the optimal fractionation schedules?

    International Nuclear Information System (INIS)

    Shibamoto, Yuta; Miyakawa, Akifumi; Otsuka, Shinya; Iwata, Hiromitsu

    2016-01-01

    In hypofractionated stereotactic radiotherapy (SRT), high doses per fraction are usually used and the dose delivery pattern is different from that of conventional radiation. The daily dose is usually given intermittently over a longer time compared with conventional radiotherapy. During prolonged radiation delivery, sublethal damage repair takes place, leading to the decreased effect of radiation. In in vivo tumors, however, this decrease in effect may be counterbalanced by rapid reoxygenation. Another issue related to hypofractionated SRT is the mathematical model for dose evaluation and conversion. The linear–quadratic (LQ) model and biologically effective dose (BED) have been suggested to be incorrect when used for hypofractionation. The LQ model overestimates the effect of high fractional doses of radiation. BED is particularly incorrect when used for tumor responses in vivo, since it does not take reoxygenation into account. Correction of the errors, estimated at 5–20%, associated with the use of BED is necessary when it is used for SRT. High fractional doses have been reported to exhibit effects against tumor vasculature and enhance host immunity, leading to increased antitumor effects. This may be an interesting topic that should be further investigated. Radioresistance of hypoxic tumor cells is more problematic in hypofractionated SRT, so trials of hypoxia-targeted agents are encouraged in the future. In this review, the radiobiological characteristics of hypofractionated SRT are summarized, and based on the considerations, we would like to recommend 60 Gy in eight fractions delivered three times a week for lung tumors larger than 2 cm in diameter

  1. A Cellular Automata-based Model for Simulating Restitution Property in a Single Heart Cell.

    Science.gov (United States)

    Sabzpoushan, Seyed Hojjat; Pourhasanzade, Fateme

    2011-01-01

    Ventricular fibrillation is the cause of the most sudden mortalities. Restitution is one of the specific properties of ventricular cell. The recent findings have clearly proved the correlation between the slope of restitution curve with ventricular fibrillation. This; therefore, mandates the modeling of cellular restitution to gain high importance. A cellular automaton is a powerful tool for simulating complex phenomena in a simple language. A cellular automaton is a lattice of cells where the behavior of each cell is determined by the behavior of its neighboring cells as well as the automata rule. In this paper, a simple model is depicted for the simulation of the property of restitution in a single cardiac cell using cellular automata. At first, two state variables; action potential and recovery are introduced in the automata model. In second, automata rule is determined and then recovery variable is defined in such a way so that the restitution is developed. In order to evaluate the proposed model, the generated restitution curve in our study is compared with the restitution curves from the experimental findings of valid sources. Our findings indicate that the presented model is not only capable of simulating restitution in cardiac cell, but also possesses the capability of regulating the restitution curve.

  2. Actions of cholera toxin and the prevention and treatment of cholera

    Science.gov (United States)

    Holmgren, Jan

    1981-07-01

    The drastic intestinal secretion of fluid and electrolytes that is characteristic of cholera is the result of reasonably well understood cellular and biochemical actions of the toxin secreted by Vibrio cholerae. Based on this understanding it is possible to devise new techniques for the treatment and prophylaxis of cholera to complement those based on fluid replacement therapy and sanitation.

  3. Physical basis for biological effect

    International Nuclear Information System (INIS)

    Goodhead, D.T.

    1987-01-01

    Absorbed dose, or particle fluence, alone, are poor predictors of the biological effectiveness of ionizing radiations. Various radiation 'quality' parameters have been proposed to account quantitatively for the differences due to type of radiation. These include LET, quality factor (Q), lineal energy, specific energy and Z 2 /β 2 . However, all of these have major shortcomings, largely because they fail to describe adequately the microscopic stochastic properties of radiation which are primarily responsible for their relative effectiveness. Most biophysical models of radiation action now agree that the biological effectiveness of radiations are to a large extent determined by their very localized spatial properties of energy deposition (perhaps DNA and associated structures) and that the probability of residual permanent cellular damage (after cellular repair) depends on the nature of this initial macromolecular damage. Common features of these models make it clear that major future advances in identifying critical physical parameters of radiations for general practical application, or to describe their fundamental mechanisms of action, require accurate knowledge of the spatial patterns of energy deposition down to distances of the order of nanometres. Therefore, adequate descriptions are required of the nature and spatial distribution of the initial charged particles and of the interaction-by-interaction structure of the ensuing charged particle tracks. Recent development and application of Monte Carlo track structure simulations have already made it possible to commence such analyses of radiobiological data. (author). 56 refs, 7 figs

  4. Myokit: A simple interface to cardiac cellular electrophysiology.

    Science.gov (United States)

    Clerx, Michael; Collins, Pieter; de Lange, Enno; Volders, Paul G A

    2016-01-01

    Myokit is a new powerful and versatile software tool for modeling and simulation of cardiac cellular electrophysiology. Myokit consists of an easy-to-read modeling language, a graphical user interface, single and multi-cell simulation engines and a library of advanced analysis tools accessible through a Python interface. Models can be loaded from Myokit's native file format or imported from CellML. Model export is provided to C, MATLAB, CellML, CUDA and OpenCL. Patch-clamp data can be imported and used to estimate model parameters. In this paper, we review existing tools to simulate the cardiac cellular action potential to find that current tools do not cater specifically to model development and that there is a gap between easy-to-use but limited software and powerful tools that require strong programming skills from their users. We then describe Myokit's capabilities, focusing on its model description language, simulation engines and import/export facilities in detail. Using three examples, we show how Myokit can be used for clinically relevant investigations, multi-model testing and parameter estimation in Markov models, all with minimal programming effort from the user. This way, Myokit bridges a gap between performance, versatility and user-friendliness. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Skin carcinomas: Radiobiological principles, radiotherapeutic techniques and clinical management

    International Nuclear Information System (INIS)

    Schmidt-Ullrich, Rupert K.; Johnson, Christopher R.

    1997-01-01

    Purpose/Objective: The course will be divided into three major topics: (1) Review of radiobiological principles as they apply to the radiotherapeutic management of skin carcinomas; (2) review of radiotherapeutic techniques including beam qualities, beam collimation, tissue dose profiles, and the relative indications of external beam irradiation vs. brachytherapy; (3) comprehensive review of the tumor biology of skin malignancies, including malignant melanoma, and of the relative indications for radiotherapeutic and/or surgical management. (1) Review of critical data which have led to currently applied principles of time-dose-volume concepts in the radiotherapeutic management of skin carcinomas. Emphasis will be placed on the relative importance of fraction size and overall treatment time on tumor control probability and acute and late normal tissue toxicity. (2) Considering that radiotherapy in the management of skin carcinomas is often used to minimize patient disfiguration and to preserve critical body functions (e.g. eye lids) the technical aspects of radiotherapy delivery are most critical. Careful evaluation of the extent of the lesions including evaluation of their depth of invasion will determine the quality of the radiation beams, orthovoltage and low energy electrons being the most useful. Beam harding for orthovoltage beams and secondary and tertiary (skin) collimation of appropriate electron beams are critical. For more extensive and deeply invasive lesions contour-shaping through customized bolus material is essential. Equally important is the familiarity with custom shielding of critical structures, such as eyes, ears, oral cavity and central nervous system structures. Brachytherapy applications in the treatment of skin carcinomas is limited but should be considered when implants with high dose uniformity can be constructed. (3) The discussion of clinical management will start with a discussion of properties and routes of spread of the diverse

  6. Skin carcinomas: radiobiological principles, radiotherapeutic techniques and clinical management

    International Nuclear Information System (INIS)

    Schmidt-Ullrich, Rupert K. A.; Johnson, Christopher R.

    1995-01-01

    Purpose/Objective: The course will be divided into three major topics: (1) Review of radiobiological principles as they apply to the radiotherapeutic management of skin carcinomas; (2) review of radiotherapeutic techniques including beam qualities, beam collimation, tissue dose profiles, and the relative indications of external beam irradiation vs. brachytherapy; (3) comprehensive review of the tumor biology of skin malignancies, including malignant melanoma, and of the relative indications for radiotherapeutic and/or surgical management. (1) Review of critical data which have lead to currently applied principles of time-dose-volume concepts in the radiotherapeutic management of skin carcinomas. Emphasis will be placed on the relative importance of fraction size and overall treatment time on tumor control probability and acute and late normal tissue toxicity. (2) Considering that radiotherapy in the management of skin carcinomas is often used to minimize patient disfiguration and to preserve critical body functions (e.g. eye lids) the technical aspects of radiotherapy delivery are most critical. Careful evaluation of the extent of the lesions including evaluation of their depth of invasion will determine the quality of the radiation beams, orthovoltage and low energy electrons being the most useful. Beam harding for orthovoltage beams and secondary and tertiary (skin) collimation of appropriate electron beams are critical. For more extensive and deeply invasive lesions contour-shaping through customized bolus material is essential. Equally important is the familiarity with custom shielding of critical structures, such as eyes, ears, oral cavity and central nervous system structures. Brachytherapy applications in the treatment of skin carcinomas is limited but should be considered when implants with high dose uniformity can be constructed. (3) The discussion of clinical management will start with a discussion of tumor biological properties of the diverse malignant

  7. Formation and action of oxygen activated species in cell cultures

    International Nuclear Information System (INIS)

    Hoffmann, M.E.; Meneghini, R.

    1982-01-01

    The differences of hydrogen peroxide sensibility of mammal cell lineages (man, mouse, chinese hamster) in culture are studied. The cellular survival and the frequency of DNA induced breaks by hydrogen peroxide are analysed. The efficiency of elimination of DNA breaks by cells is determined. The possible relation between the cell capacity of repair and its survival to hydrogen peroxide action is also discussed. (M.A.) [pt

  8. Radiobiological studies of cells in multicellular spheroids using a sequential trypsinization technique

    International Nuclear Information System (INIS)

    Giesbrecht, J.L.; Wilson, W.R.; Hill, R.P.

    1981-01-01

    The radiation response of V79 Chinese hamster cells grown as multicellular spheroids has been investigated by determining survival curves for treatment under a variety of different oxygen concentrations. Spheroids were irradiated under fully oxygenated conditions in air-equilibrated medium at 37 0 C, in medium exposed to lower oxygen tension (5% O 2 ) for times varying from 1 hr to 3 days, or under anoxic conditions. For comparison with the spheroids, using identical treatment conditions, V79 cells were grown in suspension as a subconfluent monolayer attached to Sephadex (microcarrier) beads and irradiated under fully oxygenated or anoxic conditions. The radiation response of cells at different depths within the spheroid was investigated by using a sequential trypsinization technique developed to remove eight or nine shells of cells successively from the spheroid surface. When irradiation was given under fully oxygenated conditions the outer few cell layers were more sensitive than the inner cells, a finding which is not understood. As expected the inner cells in spheroids irradiated in air (at 37 0 C) or in 5% O 2 are more resistant than the outer cells. For an acute exposure to 5% O 2 (1 hr) in the inner cells displayed full radiobiological hypoxia; however, for chronic exposures to low oxygen this was not the case. These results with the sequential trypsinization procedure suggest that the radiation response of cells in spheroids is more complex than anticipted

  9. Nitric oxide-releasing prodrug triggers cancer cell death through deregulation of cellular redox balance

    Directory of Open Access Journals (Sweden)

    Anna E. Maciag

    2013-01-01

    Full Text Available JS-K is a nitric oxide (NO-releasing prodrug of the O2-arylated diazeniumdiolate family that has demonstrated pronounced cytotoxicity and antitumor properties in a variety of cancer models both in vitro and in vivo. The current study of the metabolic actions of JS-K was undertaken to investigate mechanisms of its cytotoxicity. Consistent with model chemical reactions, the activating step in the metabolism of JS-K in the cell is the dearylation of the diazeniumdiolate by glutathione (GSH via a nucleophilic aromatic substitution reaction. The resulting product (CEP/NO anion spontaneously hydrolyzes, releasing two equivalents of NO. The GSH/GSSG redox couple is considered to be the major redox buffer of the cell, helping maintain a reducing environment under basal conditions. We have quantified the effects of JS-K on cellular GSH content, and show that JS-K markedly depletes GSH, due to JS-K's rapid uptake and cascading release of NO and reactive nitrogen species. The depletion of GSH results in alterations in the redox potential of the cellular environment, initiating MAPK stress signaling pathways, and inducing apoptosis. Microarray analysis confirmed signaling gene changes at the transcriptional level and revealed alteration in the expression of several genes crucial for maintenance of cellular redox homeostasis, as well as cell proliferation and survival, including MYC. Pre-treating cells with the known GSH precursor and nucleophilic reducing agent N-acetylcysteine prevented the signaling events that lead to apoptosis. These data indicate that multiplicative depletion of the reduced glutathione pool and deregulation of intracellular redox balance are important initial steps in the mechanism of JS-K's cytotoxic action.

  10. Cellular Particle Dynamics simulation of biomechanical relaxation processes of multi-cellular systems

    Science.gov (United States)

    McCune, Matthew; Kosztin, Ioan

    2013-03-01

    Cellular Particle Dynamics (CPD) is a theoretical-computational-experimental framework for describing and predicting the time evolution of biomechanical relaxation processes of multi-cellular systems, such as fusion, sorting and compression. In CPD, cells are modeled as an ensemble of cellular particles (CPs) that interact via short range contact interactions, characterized by an attractive (adhesive interaction) and a repulsive (excluded volume interaction) component. The time evolution of the spatial conformation of the multicellular system is determined by following the trajectories of all CPs through numerical integration of their equations of motion. Here we present CPD simulation results for the fusion of both spherical and cylindrical multi-cellular aggregates. First, we calibrate the relevant CPD model parameters for a given cell type by comparing the CPD simulation results for the fusion of two spherical aggregates to the corresponding experimental results. Next, CPD simulations are used to predict the time evolution of the fusion of cylindrical aggregates. The latter is relevant for the formation of tubular multi-cellular structures (i.e., primitive blood vessels) created by the novel bioprinting technology. Work supported by NSF [PHY-0957914]. Computer time provided by the University of Missouri Bioinformatics Consortium.

  11. Multiple Molecular and Cellular Mechanisms of Action of Lycopene in Cancer Inhibition

    Directory of Open Access Journals (Sweden)

    Cristina Trejo-Solís

    2013-01-01

    Full Text Available Epidemiological studies suggest that including fruits, vegetables, and whole grains in regular dietary intake might prevent and reverse cellular carcinogenesis, reducing the incidence of primary tumours. Bioactive components present in food can simultaneously modulate more than one carcinogenic process, including cancer metabolism, hormonal balance, transcriptional activity, cell-cycle control, apoptosis, inflammation, angiogenesis and metastasis. Some studies have shown an inverse correlation between a diet rich in fruits, vegetables, and carotenoids and a low incidence of different types of cancer. Lycopene, the predominant carotenoid found in tomatoes, exhibits a high antioxidant capacity and has been shown to prevent cancer, as evidenced by clinical trials and studies in cell culture and animal models. In vitro studies have shown that lycopene treatment can selectively arrest cell growth and induce apoptosis in cancer cells without affecting normal cells. In vivo studies have revealed that lycopene treatment inhibits tumour growth in the liver, lung, prostate, breast, and colon. Clinical studies have shown that lycopene protects against prostate cancer. One of the main challenges in cancer prevention is the integration of new molecular findings into clinical practice. Thus, the identification of molecular biomarkers associated with lycopene levels is essential for improving our understanding of the mechanisms underlying its antineoplastic activity.

  12. Lethal action of ultraviolet and visible (blue violet) radiations at defined wavelengths on human lymphoblastoid cells; action spectra and interaction sites

    Energy Technology Data Exchange (ETDEWEB)

    Tyrrell, R.M.; Werfelli, P.; Moraes, E.C. (Institut Suisse de Recherches Experimentales sur le Cancer, Lausanne)

    1984-02-01

    The repair proficient human lymphoblastoid line (TK6) has been employed to construct an action spectrum for the lethal action of ultraviolet (UV) radiation in the range 254 to 434 nm and to examine possible interactions between longer (334, 365 and 405 nm) and shorter wavelength (254 and 313 nm) radiations. The action spectrum follows a DNA absorption spectrum fairly closely out to 360 nm. As in previously determined lethal action spectra for procaryotic and eucaryotic cell populations, there is a broad shoulder in the 334 to 405 nm region which could reflect the existence of either (a) a non-DNA chromophore or (b) a unique photochemical reaction in the DNA over this region. Pre-treatment with radiation at 334 or 365 nm causes either a slight sensitivity to (low fluences) or protection from (higher fluences) subsequent exposure to radiation at a shorter wavelength (254 or 313 nm). Pre-irradiation at a visible wavelength (405 nm) at all fluence levels employed sensitizes the populations to treatment with 254 or 313 nm radiations. These interactions will influence the lethal outcome of cellular exposure to broad-band radiation sources.

  13. Lethal action of ultraviolet and visible (blue violet) radiations at defined wavelengths on human lymphoblastoid cells; action spectra and interaction sites

    International Nuclear Information System (INIS)

    Tyrrell, R.M.; Werfelli, P.; Moraes, E.C.

    1984-01-01

    The repair proficient human lymphoblastoid line (TK6) has been employed to construct an action spectrum for the lethal action of ultraviolet (UV) radiation in the range 254 to 434 nm and to examine possible interactions between longer (334, 365 and 405 nm) and shorter wavelength (254 and 313 nm) radiations. The action spectrum follows a DNA absorption spectrum fairly closely out to 360 nm. As in previously determined lethal action spectra for procaryotic and eucaryotic cell populations, there is a broad shoulder in the 334 to 405 nm region which could reflect the existence of either (a) a non-DNA chromophore or (b) a unique photochemical reaction in the DNA over this region. Pre-treatment with radiation at 334 or 365 nm causes either a slight sensitivity to (low fluences) or protection from (higher fluences) subsequent exposure to radiation at a shorter wavelength (254 or 313 nm). Pre-irradiation at a visible wavelength (405 nm) at all fluence levels employed sensitizes the populations to treatment with 254 or 313 nm radiations. These interactions will influence the lethal outcome of cellular exposure to broad-band radiation sources. (author)

  14. Hypo-fractionated treatment in radiotherapy: radio-biological models Tcp and NTCP; Tratamiento hipofraccionado en radioterapia: modelos radiobiologicos TCP y NTCP

    Energy Technology Data Exchange (ETDEWEB)

    Astudillo V, A. J.; Mitsoura, E. [Universidad Autonoma del Estado de Mexico, Facultad de Medicina, Paseo Tollocan s/n, 50180 Toluca, Estado de Mexico (Mexico); Paredes G, L. [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Resendiz G, G., E-mail: lydia.paredes@inin.gob.mx [Hospital Medica Sur, Departamento de Radioterapia, Puente de Piedra 150, Col. Toriello Guerra, 14050 Mexico D. F. (Mexico)

    2014-08-15

    At the present time the breast cancer in Mexico has the first place of incidence of the malignant neoplasia s in the women, and represents 11.34% of all the cancer cases. On the other hand, the treatments for cancer by means of ionizing radiations have been dominated under the approaches of the medical radio-oncologists which have been based on test and error by many years. The radio-biological models, as the Tcp, NTCP and dosimetric variables, for their clinical application in the conventional radiotherapy with hypo-fractionation have as purpose predicting personalized treatment plans that they present most probability of tumor control and minor probability of late reactions, becoming this way support tools in the decisions taking for the patient treatments planning of Medical Physicists and Radio-oncologists. (Author)

  15. Postgraduate studies in radiation biology in Europe

    International Nuclear Information System (INIS)

    Trott, K.R.; Lohmann, P.H.M.; Zeeland, A.A. van; Natarajan, A.T.; Schibilla, H.; Chadwick, K.; Kellerer, A.M.; Steinhaeusler, F.

    1998-01-01

    The present system of radiobiological research in universities and research centres is no longer able to train radiobiologists who have a comprehensive understanding of the entire field of radiation biology including both 'classical' and molecular radiation biology. However, such experts are needed in view of the role radiation protection plays in our societies. No single institution in Europe could now run a 1-year, full-time course which covers all aspects of the radiobiological basis of radiation protection. Therefore, a cooperative action of several universities from different EU member states has been developed and is described herein. (orig.)

  16. SU-F-T-545: Dosimetric and Radiobiological Evaluation of Dose Calculation Algorithms On Prostate Stereotactic Body Radiotherapy Using Conventional Flattened and Flattening-Filter-Free Beam

    International Nuclear Information System (INIS)

    Kang, S; Suh, T; Chung, J; Eom, K; Lee, J

    2016-01-01

    Purpose: The purpose of this study is to evaluate the dosimetric and radiobiological impact of Acuros XB (AXB) and Anisotropic Analytic Algorithm (AAA) dose calculation algorithms on prostate stereotactic body radiation therapy plans with both conventional flattened (FF) and flattening-filter free (FFF) modes. Methods: For thirteen patients with prostate cancer, SBRT planning was performed using 10-MV photon beam with FF and FFF modes. The total dose prescribed to the PTV was 42.7 Gy in 7 fractions. All plans were initially calculated using AAA algorithm in Eclipse treatment planning system (11.0.34), and then were re-calculated using AXB with the same MUs and MLC files. The four types of plans for different algorithms and beam energies were compared in terms of homogeneity and conformity. To evaluate the radiobiological impact, the tumor control probability (TCP) and normal tissue complication probability (NTCP) calculations were performed. Results: For PTV, both calculation algorithms and beam modes lead to comparable homogeneity and conformity. However, the averaged TCP values in AXB plans were always lower than in AAA plans with an average difference of 5.3% and 6.1% for 10-MV FFF and FF beam, respectively. In addition, the averaged NTCP values for organs at risk (OARs) were comparable. Conclusion: This study showed that prostate SBRT plan were comparable dosimetric results with different dose calculation algorithms as well as delivery beam modes. For biological results, even though NTCP values for both calculation algorithms and beam modes were similar, AXB plans produced slightly lower TCP compared to the AAA plans.

  17. SU-F-T-545: Dosimetric and Radiobiological Evaluation of Dose Calculation Algorithms On Prostate Stereotactic Body Radiotherapy Using Conventional Flattened and Flattening-Filter-Free Beam

    Energy Technology Data Exchange (ETDEWEB)

    Kang, S; Suh, T [The catholic university of Korea, Seoul (Korea, Republic of); Chung, J; Eom, K [Seoul National University Bundang Hospital (Korea, Republic of); Lee, J [Konkuk University Medical Center (Korea, Republic of)

    2016-06-15

    Purpose: The purpose of this study is to evaluate the dosimetric and radiobiological impact of Acuros XB (AXB) and Anisotropic Analytic Algorithm (AAA) dose calculation algorithms on prostate stereotactic body radiation therapy plans with both conventional flattened (FF) and flattening-filter free (FFF) modes. Methods: For thirteen patients with prostate cancer, SBRT planning was performed using 10-MV photon beam with FF and FFF modes. The total dose prescribed to the PTV was 42.7 Gy in 7 fractions. All plans were initially calculated using AAA algorithm in Eclipse treatment planning system (11.0.34), and then were re-calculated using AXB with the same MUs and MLC files. The four types of plans for different algorithms and beam energies were compared in terms of homogeneity and conformity. To evaluate the radiobiological impact, the tumor control probability (TCP) and normal tissue complication probability (NTCP) calculations were performed. Results: For PTV, both calculation algorithms and beam modes lead to comparable homogeneity and conformity. However, the averaged TCP values in AXB plans were always lower than in AAA plans with an average difference of 5.3% and 6.1% for 10-MV FFF and FF beam, respectively. In addition, the averaged NTCP values for organs at risk (OARs) were comparable. Conclusion: This study showed that prostate SBRT plan were comparable dosimetric results with different dose calculation algorithms as well as delivery beam modes. For biological results, even though NTCP values for both calculation algorithms and beam modes were similar, AXB plans produced slightly lower TCP compared to the AAA plans.

  18. Dynamic behavior of cellular materials and cellular structures: Experiments and modeling

    Science.gov (United States)

    Gao, Ziyang

    Cellular solids, including cellular materials and cellular structures (CMS), have attracted people's great interests because of their low densities and novel physical, mechanical, thermal, electrical and acoustic properties. They offer potential for lightweight structures, energy absorption, thermal management, etc. Therefore, the studies of cellular solids have become one of the hottest research fields nowadays. From energy absorption point of view, any plastically deformed structures can be divided into two types (called type I and type II), and the basic cells of the CMS may take the configurations of these two types of structures. Accordingly, separated discussions are presented in this thesis. First, a modified 1-D model is proposed and numerically solved for a typical type II structure. Good agreement is achieved with the previous experimental data, hence is used to simulate the dynamic behavior of a type II chain. Resulted from different load speeds, interesting collapse modes are observed, and the parameters which govern the cell's post-collapse behavior are identified through a comprehensive non-dimensional analysis on general cellular chains. Secondly, the MHS specimens are chosen as an example of type I foam materials because of their good uniformity of the cell geometry. An extensive experimental study was carried out, where more attention was paid to their responses to dynamic loadings. Great enhancement of the stress-strain curve was observed in dynamic cases, and the energy absorption capacity is found to be several times higher than that of the commercial metal foams. Based on the experimental study, finite elemental simulations and theoretical modeling are also conducted, achieving good agreements and demonstrating the validities of those models. It is believed that the experimental, numerical and analytical results obtained in the present study will certainly deepen the understanding of the unsolved fundamental issues on the mechanical behavior of

  19. Molecular mechanisms of action of bacterial exotoxins.

    Science.gov (United States)

    Balfanz, J; Rautenberg, P; Ullmann, U

    1996-07-01

    Toxins are one of the inventive strategies that bacteria have developed in order to survive. As virulence factors, they play a major role in the pathogenesis of infectious diseases. Recent discoveries have once more highlighted the effectiveness of these precisely adjusted bacterial weapons. Furthermore, toxins have become an invaluable tool in the investigation of fundamental cell processes, including regulation of cellular functions by various G proteins, cytoskeletal dynamics and neural transmission. In this review, the bacterial toxins are presented in a rational classification based on the molecular mechanisms of action.

  20. Radiobiological significance of radioactive contamination - summary assessment based on great number of measurements

    International Nuclear Information System (INIS)

    Angelov, V.; Bonchev, Ts.; Mavrodiev, V.; Kyrdzhilov, N.

    1995-01-01

    In order to facilitate quantitative and qualitative characterisation of radioactive contamination the authors introduce a relative estimate of radionuclide activity by setting as a reference the most abundant element -Co-60 in the case of the Kozloduy NPP. The ratio η i of the mean annual permissible concentration in air for each radionuclide (RPC-92) to that of Co-60 is calculated. It is found that η i has the same or close values for groups of radionuclides, e.g. η i = 2.10 -4 for 238 Pu, 239 Pu, 240 Pu, 241 Am, 244 Cm; η i = 5 for 89 Sr, 91 Y; 93 Nb, 134 Cs, 137 Cs; η i = 50 for 55 Fe, 63 Ni, 95 Zr, 95 Nb, 140 Ba, 140 La. Then it is compared to the experimentally measured values of the same quantity η iexp , derived from surface contamination data. The ratio η iexp /η i is plotted against log η i . The resulting nomograms give graphic representation of the radiobiological significance of various radionuclide groups. Data from different locations at the Kozloduy NPP are presented. It is found that the alpha emitter contamination has highest values in the Unit 1 (WWER-440) control rooms after repair. The Unit 5 (WWER-1000) has lower alpha contamination compared to WWER-440 units. 1 ref., 5 figs., 1 tab

  1. Analysis of the radiobiology of ytterbium-169 and iodine-125 permanent brachytherapy implants

    Energy Technology Data Exchange (ETDEWEB)

    Lazarescu, G.R. [Windsor Regional Cancer Center, Ontario Cancer Treatment and Research Foundation, Windsor, Canada N8W 2X3 (Canada); Battista, J.J. [London Regional Cancer Center, Ontario Cancer Treatment and Research Foundation, Dept. of Oncology and Dept. of Medical Biophysics, University of Western Ontario, London, Canada N6A 4L6 (Canada)

    1997-09-01

    Recently, Yb-169 has been considered as a potential replacement for I-125 and Pd-103 in permanent implants. In spite of the uncertainties in the parameters necessary for an accurate radiobiological modelling, the linear quadratic model can be useful in the comparative evaluation of the radiotherapeutic merit of similar implants. In order to find out if a Yb-169 permanent implant can be made biologically 'equivalent' to an I-125 implant, we studied the dependence of local control on the tumour cell radiosensitivity and on the balance between the rate of tumour cell killing and tumour cell proliferation, for rapidly and slowly proliferating tumours. The extrapolated response dose (ERD) has been calculated for tumour and late reacting normal tissue for both types of implants and the possible biological restrictions due to the normal tissue tolerance have been discussed. Our theoretical analysis is consistent with the clinical results published for I-125 permanent implants in prostate tumours and meningiomas. It predicts that Yb-169, which has only recently been used in human tumours, can provide comparable tumour control for permanent implants in slowly proliferating tumours with an initial dose rate of 13 cGy h{sup -1}. Control might be extended to rapidly proliferating tumours by increasing the initial dose rate within a range consistent with an acceptable level of normal tissue late reaction. (author)

  2. Radiobiological experiments with heavy ions: a comparison of the cross sections of different biological endpoints

    International Nuclear Information System (INIS)

    Kraft, G.

    1989-01-01

    Biological effect of heavy charged particles was studied in experiment at the Unilac on different physical, chemical and biological levels. On these experiments a large body of radiobiological data, cross sections for cell inactivation and mutation, induction of both, chromosome aberrations, and strand breaks, of DNA have been measured for different atomic numbers, from helium (z=2) to uranium (z=92), and at an LET range from 10 to 16000 keV/μm. At LET values below 100 keV/μm all data points to one specific effect form one single curve as a function of LET, independent of the atomic number of the ion. In this LET range the biological effects are independent of the particle energy or track structure and depend only on the energy transfer. Therefore LET is a good parameter in this regime. For LET values greater than 100 keV/μm this regime LET is no longer a good parameter and the physical parameters of the formation of particle track are important. The energy and angular distribution of the electrons in a solid target has to be measured. 28 refs.; 14 figs

  3. Statistical mechanics of cellular automata

    International Nuclear Information System (INIS)

    Wolfram, S.

    1983-01-01

    Cellular automata are used as simple mathematical models to investigate self-organization in statistical mechanics. A detailed analysis is given of ''elementary'' cellular automata consisting of a sequence of sites with values 0 or 1 on a line, with each site evolving deterministically in discrete time steps according to p definite rules involving the values of its nearest neighbors. With simple initial configurations, the cellular automata either tend to homogeneous states, or generate self-similar patterns with fractal dimensions approx. =1.59 or approx. =1.69. With ''random'' initial configurations, the irreversible character of the cellular automaton evolution leads to several self-organization phenomena. Statistical properties of the structures generated are found to lie in two universality classes, independent of the details of the initial state or the cellular automaton rules. More complicated cellular automata are briefly considered, and connections with dynamical systems theory and the formal theory of computation are discussed

  4. [Mechanism of action of neurotoxins acting on the inactivation of voltage-gated sodium channels].

    Science.gov (United States)

    Benoit, E

    1998-01-01

    This review focuses on the mechanism(s) of action of neurotoxins acting on the inactivation of voltage-gated Na channels. Na channels are transmembrane proteins which are fundamental for cellular communication. These proteins form pores in the plasma membrane allowing passive ionic movements to occur. Their opening and closing are controlled by gating systems which depend on both membrane potential and time. Na channels have three functional properties, mainly studied using electrophysiological and biochemical techniques, to ensure their role in the generation and propagation of action potentials: 1) a highly selectivity for Na ions, 2) a rapid opening ("activation"), responsible for the depolarizing phase of the action potential, and 3) a late closing ("inactivation") involved in the repolarizing phase of the action potential. As an essential protein for membrane excitability, the Na channel is the specific target of a number of vegetal and animal toxins which, by binding to the channel, alter its activity by affecting one or more of its properties. At least six toxin receptor sites have been identified on the neuronal Na channel on the basis of binding studies. However, only toxins interacting with four of these sites (sites 2, 3, 5 et 6) produce alterations of channel inactivation. The maximal percentage of Na channels modified by the binding of neurotoxins to sites 2 (batrachotoxin and some alkaloids), 3 (alpha-scorpion and sea anemone toxins), 5 (brevetoxins and ciguatoxins) et 6 (delta-conotoxins) is different according to the site considered. However, in all cases, these channels do not inactivate. Moreover, Na channels modified by toxins which bind to sites 2, 5 and 6 activate at membrane potentials more negative than do unmodified channels. The physiological consequences of Na channel modifications, induced by the binding of neurotoxins to sites 2, 3, 5 and 6, are (i) an inhibition of cellular excitability due to an important membrane depolarization (site

  5. Radiobiology of Small Hive Beetle (Coleoptera: Nitidulidae) and Prospects for Management Using Sterile Insect

    International Nuclear Information System (INIS)

    Downey, Danielle; Chun, Stacey; Follett, Peter

    2016-01-01

    Small hive beetle, Aethina tumida Murray (Coleoptera: Nitidulidae), is considered a serious threat to beekeeping in the Western Hemisphere, Australia, and Europe mainly due to larval feeding on honey, pollen, and brood of the European honeybee, Apis mellifera L. Control methods are limited for this pest. Studies were conducted to provide information on the radiobiology of small hive beetle and determine the potential for sterile insect releases as a control strategy. Adult males and females were equally sensitive to a radiation dose of 80 Gy and died within 5–7 d after treatment. In reciprocal crossing studies, irradiation of females only lowered reproduction to a greater extent than irradiation of males only. For matings between unirradiated males and irradiated females, mean reproduction was reduced by >99% at 45 and 60 Gy compared with controls, and no larvae were produced at 75 Gy. Irradiation of prereproductive adults of both sexes at 45 Gy under low oxygen (1–4%) caused a high level of sterility (>99%) while maintaining moderate survivorship for several weeks, and should suffice for sterile insect releases. Sterile insect technique holds potential for suppressing small hive beetle populations in newly invaded areas and limiting its spread. (author)

  6. Wireless Cellular Mobile Communications

    OpenAIRE

    Zalud, V.

    2002-01-01

    In this article is briefly reviewed the history of wireless cellular mobile communications, examined the progress in current second generation (2G) cellular standards and discussed their migration to the third generation (3G). The European 2G cellular standard GSM and its evolution phases GPRS and EDGE are described somewhat in detail. The third generation standard UMTS taking up on GSM/GPRS core network and equipped with a new advanced access network on the basis of code division multiple ac...

  7. MSAT and cellular hybrid networking

    Science.gov (United States)

    Baranowsky, Patrick W., II

    Westinghouse Electric Corporation is developing both the Communications Ground Segment and the Series 1000 Mobile Phone for American Mobile Satellite Corporation's (AMSC's) Mobile Satellite (MSAT) system. The success of the voice services portion of this system depends, to some extent, upon the interoperability of the cellular network and the satellite communication circuit switched communication channels. This paper will describe the set of user-selectable cellular interoperable modes (cellular first/satellite second, etc.) provided by the Mobile Phone and described how they are implemented with the ground segment. Topics including roaming registration and cellular-to-satellite 'seamless' call handoff will be discussed, along with the relevant Interim Standard IS-41 Revision B Cellular Radiotelecommunications Intersystem Operations and IOS-553 Mobile Station - Land Station Compatibility Specification.

  8. Radiologic science for technologists: physics, biology, and protection

    International Nuclear Information System (INIS)

    Bushong, S.C.

    1980-01-01

    The second edition of a textbook primarily for students in radiologic technology is presented. Separate chapters discuss mammography, computed tomography, diagnostic ultrasound, and design of radiologic physics. Radiation protection is specifically presented in two chapters as well as being integrated throughout the text. The fundamentals of radiobiology, molecular and cellular effects of irradiation, and early and late radiation effects comprise four chapters

  9. Quantitative radiobiology: a method of in vivo study of germ cells exposed to gamma and neutron radiation, descriptive models

    International Nuclear Information System (INIS)

    Lemaire, Guy.

    1977-01-01

    A technique of quantitative analysis of in vivo cell survival of the germ cells of male rats was developed from the gonadal weight loss observed after irradiation. This technique - both global and functional - of quantifiying a cellular damage has several advantages: cell survival is completely studied in vivo; the dose range investigated is large; the results can be extended to man. The cell survival after γ and neutron exposure thus determined was investigated in the light of four cell survival theories: LEA's target theory; KELLERER and ROSSI's theory of dual action, CHADWICKS and LEENHOUT's molecular theory, and DELATTRE's general theory of transformation systems. The experimental results were well described by each theory. It was therefore concluded that the fundamental oneness of these theories should make it possible to include them all in a strict conceptual frame [fr

  10. Top-down cellular pyramids

    Energy Technology Data Exchange (ETDEWEB)

    Wu, A Y; Rosenfeld, A

    1983-10-01

    A cellular pyramid is an exponentially tapering stack of arrays of processors (cells), where each cell is connected to its neighbors (siblings) on its own level, to a parent on the level above, and to its children on the level below. It is shown that in some situations, if information flows top-down only, from fathers to sons, then a cellular pyramid may be no faster than a one-level cellular array; but it may be possible to use simpler cells in the pyramid case. 23 references.

  11. Cellular decomposition in vikalloys

    International Nuclear Information System (INIS)

    Belyatskaya, I.S.; Vintajkin, E.Z.; Georgieva, I.Ya.; Golikov, V.A.; Udovenko, V.A.

    1981-01-01

    Austenite decomposition in Fe-Co-V and Fe-Co-V-Ni alloys at 475-600 deg C is investigated. The cellular decomposition in ternary alloys results in the formation of bcc (ordered) and fcc structures, and in quaternary alloys - bcc (ordered) and 12R structures. The cellular 12R structure results from the emergence of stacking faults in the fcc lattice with irregular spacing in four layers. The cellular decomposition results in a high-dispersion structure and magnetic properties approaching the level of well-known vikalloys [ru

  12. Radiobiological impact of dose calculation algorithms on biologically optimized IMRT lung stereotactic body radiation therapy plans

    International Nuclear Information System (INIS)

    Liang, X.; Penagaricano, J.; Zheng, D.; Morrill, S.; Zhang, X.; Corry, P.; Griffin, R. J.; Han, E. Y.; Hardee, M.; Ratanatharathom, V.

    2016-01-01

    The aim of this study is to evaluate the radiobiological impact of Acuros XB (AXB) vs. Anisotropic Analytic Algorithm (AAA) dose calculation algorithms in combined dose-volume and biological optimized IMRT plans of SBRT treatments for non-small-cell lung cancer (NSCLC) patients. Twenty eight patients with NSCLC previously treated SBRT were re-planned using Varian Eclipse (V11) with combined dose-volume and biological optimization IMRT sliding window technique. The total dose prescribed to the PTV was 60 Gy with 12 Gy per fraction. The plans were initially optimized using AAA algorithm, and then were recomputed using AXB using the same MUs and MLC files to compare with the dose distribution of the original plans and assess the radiobiological as well as dosimetric impact of the two different dose algorithms. The Poisson Linear-Quadatric (PLQ) and Lyman-Kutcher-Burman (LKB) models were used for estimating the tumor control probability (TCP) and normal tissue complication probability (NTCP), respectively. The influence of the model parameter uncertainties on the TCP differences and the NTCP differences between AAA and AXB plans were studied by applying different sets of published model parameters. Patients were grouped into peripheral and centrally-located tumors to evaluate the impact of tumor location. PTV dose was lower in the re-calculated AXB plans, as compared to AAA plans. The median differences of PTV(D 95% ) were 1.7 Gy (range: 0.3, 6.5 Gy) and 1.0 Gy (range: 0.6, 4.4 Gy) for peripheral tumors and centrally-located tumors, respectively. The median differences of PTV(mean) were 0.4 Gy (range: 0.0, 1.9 Gy) and 0.9 Gy (range: 0.0, 4.3 Gy) for peripheral tumors and centrally-located tumors, respectively. TCP was also found lower in AXB-recalculated plans compared with the AAA plans. The median (range) of the TCP differences for 30 month local control were 1.6 % (0.3 %, 5.8 %) for peripheral tumors and 1.3 % (0.5 %, 3.4 %) for centrally located tumors. The lower

  13. Comparison of the dose-effect relationship for UV radiation and ionizing radiation

    International Nuclear Information System (INIS)

    Leenhouts, H.P.; Sijsma, M.J.; Chadwick, K.H.

    1990-06-01

    Ionizing radiation and ultraviolet radiation (UV) are both physical agents with mutagenic and carcinogenic properties. However, there are some basic differences in the fundamental mechanism of their interaction with biological material that may have consequences for risk assessment. In this paper the dose-effect relationships for gamma radiation and UV at cellular level will be used to demonstrate the different radio-biological effectiveness of both agents. The results will be discussed in the framework of a biophysical model, based on the assumption that DNA doublestranded lesions are crucial for the cytotoxic action. After exposure to ionizing radiation, the lesions are fixed immediately following irradiation, but after UV exposure the lethal lesions are recognized only in the next DNA synthesis phase. The combination of this concept with the mechanism of lesion induction and the possibility of repair, leads to different dose and time relationships for the radiation effects of both agents. The possible consequences for risk assessment at low levels will be discussed. (author). 9 refs.; 5 figs

  14. Lengthening our perspective: morphological, cellular, and molecular responses to eccentric exercise.

    Science.gov (United States)

    Hyldahl, Robert D; Hubal, Monica J

    2014-02-01

    The response of skeletal muscle to unaccustomed eccentric exercise has been studied widely, yet it is incompletely understood. This review is intended to provide an up-to-date overview of our understanding of how skeletal muscle responds to eccentric actions, with particular emphasis on the underlying molecular and cellular mechanisms of damage and recovery. This review begins by addressing the question of whether eccentric actions result in physical damage to muscle fibers and/or connective tissue. We next review the symptomatic manifestations of eccentric exercise (i.e., indirect damage markers, such as delayed onset muscle soreness), with emphasis on their relatively poorly understood molecular underpinnings. We then highlight factors that potentially modify the muscle damage response following eccentric exercise. Finally, we explore the utility of using eccentric training to improve muscle function in populations of healthy and aging individuals, as well as those living with neuromuscular disorders. Copyright © 2013 Wiley Periodicals, Inc.

  15. CELLULAR RESPONSES TO EGG-OIL (CHARISMON©

    Directory of Open Access Journals (Sweden)

    Jürgen Bereiter-Hahn

    2014-01-01

    Full Text Available Egg-oil (Charismon© is known for its beneficial action in wound healing and other skin irritancies and its antibacterial activity. The physiological basis for these actions has been investigated using cells in culture: HaCaT-cells (immortalized human keratinocytes, human endothelial cells in culture (HUVEC, peripheral blood mononuclear lymphocytes (PBML and a full thickness human skin model (FTSM. Emphasis was on the influence of egg-oil on cell migration and IL-8 production in HaCaT cells, respiration, mitochondrial membrane potential, reactive oxygen (ROS production and proliferation in HUVEC and HaCaT cells, cytokine and interleukin production in PBML and UV-light induced damage of FTSM. IL-8 production by HaCaT cells is stimulated by egg-oil whilst in phythemagglutinin-activated PBMLs production of the interleukins IL-2, IL-6, IL-10 and IFN-γ and TFN-α is reduced. ROS-production after H2O2 stimulation first is enhanced but later on reduced. Respiration becomes activated due to partial uncoupling of the mitochondrial respiratory chain and proliferation of HaCaT and HUVEC is reduced. Recovery of human epidermis cells in FTSM after UV-irradiation is strongly supported by egg-oil. These results support the view that egg-oil acts through reduction of inflammatory processes and ROS production. Both these processes are equally important in cellular aging as in healing of chronic wounds.

  16. WE-AB-202-11: Radiobiological Modeling of Tumor Response During Radiotherapy Based On Pre-Treatment Dynamic PET Imaging Data

    Energy Technology Data Exchange (ETDEWEB)

    Crispin-Ortuzar, M; Grkovski, M; Beattie, B; Lee, N; Riaz, N; Humm, J; Jeong, J; Fontanella, A; Deasy, J [Memorial Sloan Kettering Cancer Center, New York, NY (United States)

    2016-06-15

    Purpose: To evaluate the ability of a multiscale radiobiological model of tumor response to predict mid-treatment hypoxia images, based on pretreatment imaging of perfusion and hypoxia with [18-F]FMISO dynamic PET and glucose metabolism with [18-F]FDG PET. Methods: A mechanistic tumor control probability (TCP) radiobiological model describing the interplay between tumor cell proliferation and hypoxia (Jeong et al., PMB 2013) was extended to account for intra-tumor nutrient heterogeneity, dynamic cell migration due to nutrient gradients, and stromal cells. This extended model was tested on 10 head and neck cancer patients treated with chemoradiotherapy, randomly drawn from a larger MSKCC protocol involving baseline and mid-therapy dynamic PET scans. For each voxel, initial fractions of proliferative and hypoxic tumor cells were obtained by finding an approximate solution to a system of linear equations relating cell fractions to voxel-level FDG uptake, perfusion (FMISO K{sub 1}) and hypoxia (FMISO k{sub 3}). The TCP model then predicted their evolution over time up until the mid treatment scan. Finally, the linear model was reapplied to predict each lesion’s median hypoxia level (k{sub 3}[med,sim]) which in turn was compared to the FMISO k{sub 3}[med] measured at mid-therapy. Results: The average k3[med] of the tumors in pre-treatment scans was 0.0035 min{sup −1}, with an inter-tumor standard deviation of σ[pre]=0.0034 min{sup −1}. The initial simulated k{sub 3}[med,sim] of each tumor agreed with the corresponding measurements within 0.1σ[pre]. In 7 out of 10 lesions, the mid-treatment k{sub 3}[med,sim] prediction agreed with the data within 0.3σ[pre]. The remaining cases corresponded to the most extreme relative changes in k{sub 3}[med]. Conclusion: This work presents a method to personalize the prediction of a TCP model using pre-treatment kinetic imaging data, and validates the modeling of radiotherapy response by predicting changes in median hypoxia

  17. Biochemical endpoints of glucocorticoid hormone action

    Energy Technology Data Exchange (ETDEWEB)

    Young, D.A.; Nicholson, M.L.; Guyette, W.A.; Giddings, S.J.; Mendelsohn, S.L.; Nordeen, S.K.; Lyons, R.T.

    1978-01-01

    Both the rapidly evolving metabolic effects of glucocorticoids and the more slowly developing lethal actions appear to be initiated via the synthesis of new mRNAs and proteins. The chronic suppression of cell growth may be the consequence of suppression of overall rates of protein synthesis (and probably RNA and DNA synthesis as well) that in turn may represent the cellular response to the small changes in ratios of adenine nucleotides that result from the suppression of oxidative ATP production. The inhibition of glucose transport may also play a role here to prevent a compensatory increase in glycolytic ATP production. Some other hormone actions, the decrease in the ability of cells to concentrate AIB and the increase in nuclear fragility are unrelated to, and evolve separately from, the hormonal inhibitions on energy production. Cell killing is not the result of suppression of protein synthesis, nor of hormone-induced increases in calcium uptake. While the mechanisms are unknown, the increase in nuclear fragility appears to be the earliest measure of their operation. In tumor cells resistance to lethal actions of glucocorticoids may emerge via the selection of cells with hardier membranes, that are better able to withstand the intracellular destructive events set in motion by high levels of glucocorticoids.

  18. HSP as bio dosemeters; HSP como biodosimetros

    Energy Technology Data Exchange (ETDEWEB)

    Manzanares A, E; Vega C, H R [Grupo Academico de Radiobiologia, UAZ, A.P. 336, 98000 Zacatecas (Mexico)

    2005-07-01

    A review of the more important passages for the field of the radiological protection, from the discovery, beginnings of the utilization of the radiations emitting, passing to the legislation proposals and the transformations that had been suffer to establish the international standards of radiological protection. The paradigms on the effects and chronologically the emanated discoveries of the cellular research and the measurement of cellular products in the species and the diverse alive beings making emphasis in evaluating the expression of the heat-shock proteins caused by low doses of gamma radiation, these are used as radiation bio monitors and of other agents that cause cellular stress and lastly a prospective of the future of the radiobiology. (Author)

  19. HSP as bio dosemeters

    International Nuclear Information System (INIS)

    Manzanares A, E.; Vega C, H.R.

    2005-01-01

    A review of the more important passages for the field of the radiological protection, from the discovery, beginnings of the utilization of the radiations emitting, passing to the legislation proposals and the transformations that had been suffer to establish the international standards of radiological protection. The paradigms on the effects and chronologically the emanated discoveries of the cellular research and the measurement of cellular products in the species and the diverse alive beings making emphasis in evaluating the expression of the heat-shock proteins caused by low doses of gamma radiation, these are used as radiation bio monitors and of other agents that cause cellular stress and lastly a prospective of the future of the radiobiology. (Author)

  20. Cellular automata analysis and applications

    CERN Document Server

    Hadeler, Karl-Peter

    2017-01-01

    This book focuses on a coherent representation of the main approaches to analyze the dynamics of cellular automata. Cellular automata are an inevitable tool in mathematical modeling. In contrast to classical modeling approaches as partial differential equations, cellular automata are straightforward to simulate but hard to analyze. In this book we present a review of approaches and theories that allow the reader to understand the behavior of cellular automata beyond simulations. The first part consists of an introduction of cellular automata on Cayley graphs, and their characterization via the fundamental Cutis-Hedlund-Lyndon theorems in the context of different topological concepts (Cantor, Besicovitch and Weyl topology). The second part focuses on classification results: What classification follows from topological concepts (Hurley classification), Lyapunov stability (Gilman classification), and the theory of formal languages and grammars (Kůrka classification). These classifications suggest to cluster cel...

  1. The WLC principle for action-oriented perception

    Science.gov (United States)

    Arena, Paolo; Fortuna, Luigi; Lombardo, Davide; Patané, Luca; Velarde, Manuel G.

    2007-05-01

    In this paper a new methodology for action-oriented perception will be introduced. It is based on a previous method that used Turing Patterns in CNNs for the arousal of "perceptual states" as representation of the environmental condition. The emerging patterns were associated to codes which gave rise to learnable actions on a moving robot. Recently the new paradigm of Winnerless Competition (WLC) was taken into consideration to represent a suitable, bioinspired and efficient method to generate sequences of neural activations, strictly related to the spatial-temporal activity of input sensors. This fascinating property was recently peculiarly measured in the olfactory system, in particular in groups of neurons belonging to the insects' Antennal Lobe and to the mammalians' Olfactory Bulb. Taking inspiration from these experimental results and from the analytical model of the WLC, a cellular nonlinear model generating sequences of cell activation, representing the input pattern at the sensory level, will be used in an action-oriented perception framework. In fact simulation results showed the potentiality of the WLC approach to design dynamic networks for discrimination and classification, with a potentially huge memory capacity. In the present manuscript the WLC principle, implemented in a network of FitzHugh Nagumo neurons will be used within the whole framework for action-oriented perception, and the results will be applied to a roving robot.

  2. International conference '20 years after Chernobyl: strategy for recovery and sustainable development of the affected regions'. Abstracts proceeding; Mezhdunarodnaya konferentsiya 'Chernobyl' 20 let spustya. strategiya vosstanovleniya i ustojchivogo razvitiya postradavshikh regionov'. Sbornik tezisov

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2006-04-15

    Proceeding contains abstracts corresponding to main topics of the conference - Rehabilitation of the contaminated territories; Social and economic problems; Medical, social and psychological consequences; Dosimetry; Radioecological and radiobiological consequences; Joint action of Belarus and Russia to mitigate the consequences of the Chernobyl catastrophe.

  3. Physics and radiobiology of heavy charged particles in relation to the use of ion beams for therapy

    International Nuclear Information System (INIS)

    Kraft, G.; Haberer, T.; Schardt, D.; Scholz, M.

    1993-07-01

    Heavy charged particles are the most advanced tool of an external subcutane radiotherapy of deep seated tumors. Small angular- and lateral-scattering and the increase of the energy deposition with penetration depth are the physical basis for a more efficient tumor targeting. High biological efficiency in the tumor is the prerequisite for a successful treatment of tumors radioresistant against sparsely ionizing radiation. The possibility to perform target conform irradiation and to control the achieved/actual distribution using PET techniques guarantees that biological highly efficient stepping particles can be restricted to the tumor volume only. Although the physical and radiobiological properties of ion beams are very favourable for therapy, the necessity to produce these particles in an accelerator restricts a general application of heavy ions up to now. Presently the heavy ion accelerator SIS at GSI is the only source of heavy ion beams, sufficient in energy and intensity for therapy. A therapy unit is in preparation at GSI, the status of this project is given at the end of the paper. (orig.)

  4. Transfer of Minibeam Radiation Therapy into a cost-effective equipment for radiobiological studies: a proof of concept.

    Science.gov (United States)

    Prezado, Y; Dos Santos, M; Gonzalez, W; Jouvion, G; Guardiola, C; Heinrich, S; Labiod, D; Juchaux, M; Jourdain, L; Sebrie, C; Pouzoulet, F

    2017-12-11

    Minibeam radiation therapy (MBRT) is an innovative synchrotron radiotherapy technique able to shift the normal tissue complication probability curves to significantly higher doses. However, its exploration was hindered due to the limited and expensive beamtime at synchrotrons. The aim of this work was to develop a cost-effective equipment to perform systematic radiobiological studies in view of MBRT. Tumor control for various tumor entities will be addressable as well as studies to unravel the distinct biological mechanisms involved in normal and tumor tissues responses when applying MBRT. With that aim, a series of modifications of a small animal irradiator were performed to make it suitable for MBRT experiments. In addition, the brains of two groups of rats were irradiated. Half of the animals received a standard irradiation, the other half, MBRT. The animals were followed-up for 6.5 months. Substantial brain damage was observed in the group receiving standard RT, in contrast to the MBRT group, where no significant lesions were observed. This work proves the feasibility of the transfer of MBRT outside synchrotron sources towards a small animal irradiator.

  5. Radiobiological investigations of soft X-rays near carbon, nitrogen, oxygen K-shell edges on Aspergillus oryzae spores

    International Nuclear Information System (INIS)

    Chen, L.; Jiang, S. P.; Wan, L. B.; Ma, X. D.; Li, M. F.

    2008-01-01

    Soft X-rays at carbon, nitrogen, oxygen K-shell edges have special radiobiological effects. Using Aspergillus oryzae spores as sample, the radiation effects of soft X-rays near the K-shell edges of C, N and O elements from synchrotron radiation were investigated. Also the dose depositions of different X-ray energies in spore were discussed. At the same time, the spores were irradiated by gamma rays from 60 Co and relative biological effects were compared with those produced by soft X-rays. The results showed that soft X-rays near K-shell edges of O element had higher ability of radiation damage than that of X-rays near K-shell edges of C and N elements as compared with one another. But they all had higher killing abilities per unit dose than that of gamma rays from 60 Co. The relative biological effects (RBEs), the comparison of dose to gamma rays at 10% survival level, of the three soft X-rays were 1.65, 1.73 and 1.91, respectively. (authors)

  6. MIMO Communication for Cellular Networks

    CERN Document Server

    Huang, Howard; Venkatesan, Sivarama

    2012-01-01

    As the theoretical foundations of multiple-antenna techniques evolve and as these multiple-input multiple-output (MIMO) techniques become essential for providing high data rates in wireless systems, there is a growing need to understand the performance limits of MIMO in practical networks. To address this need, MIMO Communication for Cellular Networks presents a systematic description of MIMO technology classes and a framework for MIMO system design that takes into account the essential physical-layer features of practical cellular networks. In contrast to works that focus on the theoretical performance of abstract MIMO channels, MIMO Communication for Cellular Networks emphasizes the practical performance of realistic MIMO systems. A unified set of system simulation results highlights relative performance gains of different MIMO techniques and provides insights into how best to use multiple antennas in cellular networks under various conditions. MIMO Communication for Cellular Networks describes single-user,...

  7. Actions of vasoactive intestinal peptide and secretin on chief cells prepared from guinea pig stomach

    International Nuclear Information System (INIS)

    Sutliff, V.E.; Raufman, J.P.; Jensen, R.T.; Gardner, J.D.

    1986-01-01

    Vasoactive intestinal peptide and secretin increased cellular cAMP and pepsinogen secretion in dispersed chief cells from guinea pig gastric mucosa. With each peptide there was a close correlation between the dose-response curve for changes in cellular cAMP and that for changes in pepsinogen secretion. Vasoactive intestinal peptide- (10-28) and secretin- (5-27) had no agonist activity and antagonized the actions of vasoactive intestinal peptide and secretin on cellular cAMP and pepsinogen secretion. Studies of binding of 125 I-vasoactive intestinal peptide and of 125 -secretin indicated that gastric chief cells possess four classes of binding sites for vasoactive intestinal peptide and secretin and that occupation of two of these classes of binding sites correlates with the abilities of vasoactive intestinal peptide and secretin to increase cellular cAMP and pepsinogen secretion. What function, in any, is mediated by occupation by the other two classes of binding sites remains to be determined

  8. Assessment of the role of microdosimetry in radiobiology

    International Nuclear Information System (INIS)

    Goodhead, D.T.

    1982-01-01

    A brief outline is given of the concepts of microdosimetry and the development of the theory of dual radiation action, which was proposed as the link between the physical properties of radiation (microdosimetry) and their biological effects. A good deal of experimental evidence was consistent with the theory in its original site model form, but there were also areas of significant disagreement. More recent experiments with ultrasoft x rays and beams of correlated ions have provided critical tests which have shown that the site model does not give an adequate description of the mechanism of radiation action. A large proportion, at least, of the radiation-induced lesions are produced by highly localized energy concentrations without the need for long-range interaction of sublesions. Attempts have been made to allow for such lesions within the original postulates of the theory of dual radiation action by development of the distance model or generalized formalism using a distance-dependent interaction probability. Some of the present limitations of this approach are discussed. An alternative hypothesis, involving dose-dependent repair acting directly upon the lesions, is described. A comparison is made between consequences of these two alternative approaches. The validity of the application of microdosimetric measurements to a variety of problems is considered

  9. Cellular communications a comprehensive and practical guide

    CERN Document Server

    Tripathi, Nishith

    2014-01-01

    Even as newer cellular technologies and standards emerge, many of the fundamental principles and the components of the cellular network remain the same. Presenting a simple yet comprehensive view of cellular communications technologies, Cellular Communications provides an end-to-end perspective of cellular operations, ranging from physical layer details to call set-up and from the radio network to the core network. This self-contained source forpractitioners and students represents a comprehensive survey of the fundamentals of cellular communications and the landscape of commercially deployed

  10. Radioembolization of hepatocarcinoma with 90Y glass microspheres: development of an individualized treatment planning strategy based on dosimetry and radiobiology

    International Nuclear Information System (INIS)

    Chiesa, C.; Maccauro, M.; Aliberti, G.; Padovano, B.; Seregni, E.; Crippa, F.; Mira, M.; Negri, A.; Spreafico, C.; Morosi, C.; Civelli, E.; Lanocita, R.; Marchiano, A.; Romito, R.; Sposito, C.; Bhoori, S.; Facciorusso, A.; Mazzaferro, V.; Camerini, T.; Carrara, M.; Pellizzari, S.; Migliorisi, M.; De Nile, M.C.

    2015-01-01

    The aim of this study was to optimize the dosimetric approach and to review the absorbed doses delivered, taking into account radiobiology, in order to identify the optimal methodology for an individualized treatment planning strategy based on 99m Tc-macroaggregated albumin (MAA) single photon emission computed tomography (SPECT) images. We performed retrospective dosimetry of the standard TheraSphere registered treatment on 52 intermediate (n = 17) and advanced (i.e. portal vein thrombosis, n = 35) hepatocarcinoma patients with tumour burden < 50 % and without obstruction of the main portal vein trunk. Response was monitored with the densitometric radiological criterion (European Association for the Study of the Liver) and treatment-related liver decompensation was defined ad hoc with a time cut-off of 6 months. Adverse events clearly attributable to disease progression or other causes were not attributed to treatment. Voxel dosimetry was performed with the local deposition method on 99m Tc-MAA SPECT images. The reconstruction protocol was optimized. Concordance of 99m Tc-MAA and 90 Y bremsstrahlung microsphere biodistributions was studied in 35 sequential patients. Two segmentation methods were used, based on SPECT alone (home-made code) or on coregistered SPECT/CT images (IMALYTICS trademark by Philips). STRATOS trademark absorbed dose calculation was validated for 90 Y with a single time point. Radiobiology was used introducing other dosimetric variables besides the mean absorbed dose D: equivalent uniform dose (EUD), biologically effective dose averaged over voxel values (BED ave ) and equivalent uniform biologically effective dose (EUBED). Two sets of radiobiological parameters, the first derived from microsphere irradiation and the second from external beam radiotherapy (EBRT), were used. A total of 16 possible methodologies were compared. Tumour control probability (TCP) and normal tissue complication probability (NTCP) were derived. The area under the

  11. Characteristic 8 keV X rays possess radiobiological properties of higher-LET radiation.

    Science.gov (United States)

    Shridhar, Ravi; Estabrook, William; Yudelev, Mark; Rakowski, Joseph; Burmeister, Jay; Wilson, George D; Joiner, Michael C

    2010-03-01

    Electronic brachytherapy systems are being developed that can deliver X rays of varying energy depending on the material of a secondary target. A copper target produces characteristic 8 keV X rays. Our aim was to determine whether 8 keV X rays might deliver greater biological effectiveness than megavoltage photons. Cells of the U251 human glioma cell line were used to compare the biological effects of 8 keV X rays and (60)Co gamma rays in terms of relative biological effectiveness (RBE), oxygen enhancement ratio (OER), and DNA damage. The RBE at 50% and 10% survival was 2.6 and 1.9, respectively. At 50% survival, the OER for cells treated with 8 keV X rays was 1.6 compared with 3.0 for (60)Co gamma rays. The numbers of H2AX foci per Gy after treatment with 8 keV X rays and (60)Co gamma rays were similar; however, the size of the foci generated at 8 keV was significantly larger, possibly indicating more complex DNA damage. The mean area of H2AX foci generated by 8 keV X rays was 0.785 microm(2) (95% CI: 0.756-0.814) compared with 0.491 microm(2) (95% CI: 0.462-0.520) for (60)Co gamma rays (P X rays produce two to three times the biological effectiveness of megavoltage photons, with a radiobiological profile similar to higher-LET radiations.

  12. Functional and histological assessment of the radiobiology of normal rat lung in BNCT

    International Nuclear Information System (INIS)

    Kiger, J.L.; Riley, K.J.; Binns, P.J.; Harling, O.K.; Coderre, J.A.; Kiger, W.S. III; Patel, H.

    2006-01-01

    This study investigated the radiobiology and sensitivity of the normal rat lung to Boron Neutron Capture Therapy (BNCT) radiation. Rat thorax irradiations were carried out with x-rays or with neutrons in the presence or absence of p-boronophenylalanine (BPA). Lung damage were assessed functionally with breathing rate measurement up to 180 days after irradiation and then histologically. Breathing rates 20% (∼3 σ) above the control group (sham-irradiated rats) mean were considered as positive responses to lung radiation damage. Though most responding animals demonstrated radiation induced pneumonitis (≤110 days) as well as pulmonary fibrosis (>110 days), some animals receiving neutrons plus BPA showed only the latter. The breathing rate dose response data were fit using probit analysis. The ED 50 values measured for x-rays, neutron beam only, and neutrons plus BPA were 11.5±0.4 Gy, 9.2±0.5 Gy, and 6.7±0.4 Gy, respectively. The biological weighting factors for the neutron beam (n+γ), the thermal neutron dose component, and the 10 B dose component were determined to be 1.2±0.1, 2.2±0.4, and 2.3±0.3, respectively. The histological dose response curves were linear. Consistent with the functional assay, the weighting factors measured histologically were 1.2±0.1 for the thermal neutron beam and 1.9±0.2 for the 10 B dose component. (author)

  13. A review of the nonpressor and nonantidiuretic actions of the hormone vasopressin

    Directory of Open Access Journals (Sweden)

    Gaurang P Mavani

    2015-03-01

    Full Text Available The pressor and antidiuretic actions of arginine vasopressin (AVP have been well documented. This review focuses on the less widely appreciated actions of AVP which also have important physiologic functions and when better understood may provide important insights into common disease states. These actions include effects on pain perception and bone structure as well as important relationships to the varied components of metabolic syndrome. These include effects on blood glucose, lipid levels, and blood pressure. AVP may also play a role in the progression of chronic kidney disease and effect physiologic changes relating to aging, abnormal social behavior and cognitive function. Important cellular responses including cell proliferation, inflammation and control of infection and their relationship to AVP are described. Finally, the effects of AVP on hemostasis and the hypothalamic-pituitary-adrenal access are noted. The goal of this summary of the various actions of AVP is to direct attention to the potential benefits of research in these underemphasized areas of importance.

  14. Magnetohydrodynamics cellular automata

    International Nuclear Information System (INIS)

    Hatori, Tadatsugu.

    1990-02-01

    There has been a renewal of interest in cellular automata, partly because they give an architecture for a special purpose computer with parallel processing optimized to solve a particular problem. The lattice gas cellular automata are briefly surveyed, which are recently developed to solve partial differential equations such as hydrodynamics or magnetohydrodynamics. A new model is given in the present paper to implement the magnetic Lorentz force in a more deterministic and local procedure than the previous one. (author)

  15. Magnetohydrodynamic cellular automata

    Energy Technology Data Exchange (ETDEWEB)

    Hatori, Tadatsugu [National Inst. for Fusion Science, Nagoya (Japan)

    1990-03-01

    There has been a renewal of interest in cellular automata, partly because they give an architecture for a special purpose computer with parallel processing optimized to solve a particular problem. The lattice gas cellular automata are briefly surveyed, which are recently developed to solve partial differential equations such as hydrodynamics or magnetohydrodynamics. A new model is given in the present paper to implement the magnetic Lorentz force in a more deterministic and local procedure than the previous one. (author).

  16. Magnetohydrodynamic cellular automata

    International Nuclear Information System (INIS)

    Hatori, Tadatsugu

    1990-01-01

    There has been a renewal of interest in cellular automata, partly because they give an architecture for a special purpose computer with parallel processing optimized to solve a particular problem. The lattice gas cellular automata are briefly surveyed, which are recently developed to solve partial differential equations such as hydrodynamics or magnetohydrodynamics. A new model is given in the present paper to implement the magnetic Lorentz force in a more deterministic and local procedure than the previous one. (author)

  17. Modeling cellular systems

    CERN Document Server

    Matthäus, Franziska; Pahle, Jürgen

    2017-01-01

    This contributed volume comprises research articles and reviews on topics connected to the mathematical modeling of cellular systems. These contributions cover signaling pathways, stochastic effects, cell motility and mechanics, pattern formation processes, as well as multi-scale approaches. All authors attended the workshop on "Modeling Cellular Systems" which took place in Heidelberg in October 2014. The target audience primarily comprises researchers and experts in the field, but the book may also be beneficial for graduate students.

  18. Discrepancies between measured changes of radiobiological hypoxic fraction and oxygen tension monitoring using two assay systems

    International Nuclear Information System (INIS)

    Sasai, K.; Brown, J.M.

    1994-01-01

    This study was conducted to assess the ability of computerized pO 2 histography to measure changes in tumor oxygenation produced by low oxygen breathing. Female syngeneic C3H/Km mice bearing SCC VII/St carcinomas were used in these experiments. Changes in tumor oxygenation produced by the mice breathing 10% oxygen were assessed with computerized pO2 histography, 3 H-misonidazole binding, and the paired survival curve assay of radiosensitivity. The hypoxic cell fraction of the tumors in mice breathing 10% oxygen was 3.1 times higher than that of tumors in mice breathing normal air determined by an in vivo-in vitro clonogenic assay. Binding of radiolabeled misonidazole to the tumors in mice breathing 10% oxygen was also significantly higher than that to tumors in mice breathing normal air (p 2 value for the tumor. The number of pO 2 readings lower than 5 mmHg in the tumor was not affected by the 10% oxygen breathing. These findings indicate that increases in radiobiological hypoxic fraction produced by lower blood oxygen levels may not correlate well with the results of polarographic measurements of tumor pO 2 levels. 29 refs., 4 figs., 1 tab

  19. Curcumin-induced inhibition of cellular reactive oxygen species generation: novel therapeutic implications.

    Science.gov (United States)

    Balasubramanyam, M; Koteswari, A Adaikala; Kumar, R Sampath; Monickaraj, S Finny; Maheswari, J Uma; Mohan, V

    2003-12-01

    There is evidence for increased levels of circulating reactive oxygen species (ROS) in diabetics, as indirectly inferred by the findings of increased lipid peroxidation and decreased antioxidant status. Direct measurements of intracellular generation of ROS using fluorescent dyes also demonstrate an association of oxidative stress with diabetes. Although phenolic compounds attenuate oxidative stress-related tissue damage, there are concerns over toxicity of synthetic phenolic antioxidants and this has considerably stimulated interest in investigating the role of natural phenolics in medicinal applications. Curcumin (the primary active principle in turmeric, Curcuma longa Linn.) has been claimed to represent a potential antioxidant and antiinflammatory agent with phytonutrient and bioprotective properties. However there are lack of molecular studies to demonstrate its cellular action and potential molecular targets. In this study the antioxidant effect of curcumin as a function of changes in cellular ROS generation was tested. Our results clearly demonstrate that curcumin abolished both phorbol-12 myristate-13 acetate (PMA) and thapsigargin-induced ROS generation in cells from control and diabetic subjects. The pattern of these ROS inhibitory effects as a function of dose-dependency suggests that curcumin mechanistically interferes with protein kinase C (PKC) and calcium regulation. Simultaneous measurements of ROS and Ca2+ influx suggest that a rise in cytosolic Ca2+ may be a trigger for increased ROS generation. We suggest that the antioxidant and antiangeogenic actions of curcumin, as a mechanism of inhibition of Ca2+ entry and PKC activity, should be further exploited to develop suitable and novel drugs for the treatment of diabetic retinopathy and other diabetic complications.

  20. The use of flow cytometry in radiation biology

    International Nuclear Information System (INIS)

    Szekely, J.G.; Raaphorst, G.P.; Lobreau, A.U.; Einspenner, M.; Sargent, M.; Azzam, E.I.

    1989-09-01

    The flow cytometer has been used in a number of projects at the Whiteshell Nuclear Research Establishment, Pinawa, Manitoba, Canada. In this report we have summarized the methods and results obtained in the cellular radiobiology program. The techniques used in the program included live/dead analysis in lymphocytes, identification of bone-marrow subsets, chromosome analysis, cell-cycle analysis, cell sorting and the quantification of surface antigens