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Tumor production in Syrian hamsters following inhalation of PuO/sub 2/--ZrO/sub 2/ aerosol

Description: Syrian golden hamsters of both sexes were exposed to aerosols of ZrO/sub 2/ containing PuO/sub 2/. The starting material in the aerosol generator also had a small amount of /sup 57/Co added as a tracer. The mixture of all three constituents was nebulized and the droplets passed through a heating column at 1000/sup 0/C. Aerosol sampling was accomplished with a cascade impactor and electrostatic precipitator. The median aerodynamic diameters in all inhalation runs were approximately 2 ..mu..m wit… more
Date: January 1, 1978
Creator: Thomas, R. G. & Smith, D. M.
Partner: UNT Libraries Government Documents Department
open access

Clonal theory of radiation carcinogenesis

Description: In some cases, usually involving high-LET radiations, the dose response at low doses follows a power function of dose with exponent less than one over a wide dose range. This type of response is of great interest since (a) it implies greater effect per unit dose at progressively smaller doses, and (b) it is not predicted by most models and theories of radiobiology. A theoretical framework is presented for responses having the above characteristics over a dose range extending over a factor of 10… more
Date: January 1, 1982
Creator: Baum, J.W.
Partner: UNT Libraries Government Documents Department
open access

TRITOX: a multiple parameter evaluation of tritium toxicity

Description: The increased use of nuclear reactors for power generation will lead to the introduction of tritium into the environment. The need for assessing possible immediate and long-term effects of exposure to this tritium led to the development of a broad program directed towards evaluating the possible somatic and genetic effects of continuous exposure to tritiated water (HTO). Among the parameters measured are the genetic, cytogenetic, reproductive efficiency, growth, nonspecific lifetime shortening,… more
Date: January 1, 1982
Creator: Carsten, A.L.
Partner: UNT Libraries Government Documents Department
open access

Analytical review of structure and regulation of hemopoiesis

Description: The development of knowledge on the structure of hemopoiesis and its regulation can be divided into four broad areas: descriptive morphology, kinetics of cell proliferation, regulation of rates of cell proliferation through interaction of molecular regulators and their cell surface receptors, and clinical applications. 60 refs., 6 figs.
Date: January 1, 1987
Creator: Cronkite, E.P.
Partner: UNT Libraries Government Documents Department
open access

DNA repair in spermatocytes and spermatids of the mouse

Description: When male mice are exposed to chemical agents that reach the germ cells several outcomes are possible in terms of the germ cell unscheduled DNA synthesis (UDS) response and removal of DNA adducts. It is possible that: the chemical binds to the DNA and induces a UDS response with concomittant removal of DNA adducts; the chemical binds to the DNA but no UDS response is induced; or the chemical does not bind to DNA and no UDS is induced. Many mutagens have been shown to induce a UDS response in po… more
Date: January 1, 1982
Creator: Sega, G.A.
Partner: UNT Libraries Government Documents Department
open access

Dose-rate models for human survival after exposure to ionizing radiation

Description: This paper reviews new estimates of the L/sub 50/ in man by Mole and by Rotblat, the biological processes contributing to hematologic death, the collection of animal experiments dealing with hematologic death, and the use of regression analysis to make new estimates of human mortality based on all relevant animal studies. Regression analysis of animal mortality data has shown that mortality is dependent strongly on dose rate, species, body weight, and time interval over which the exposure is de… more
Date: January 1, 1986
Creator: Jones, T.D.; Morris, M.D. & Young, R.W.
Partner: UNT Libraries Government Documents Department
open access

Qualitative analysis of mouse specific-locus mutations: information on genetic organization, gene expression, and the chromosomal nature of induced lesions

Description: Analysis of mouse specific-locus (SL) mutations at three loci has identified over 33 distinct complementation groups - most of which are probably overlapping deficiencies - and 13 to 14 new functional units. The complementation maps that have been generated for the d-se and c regions include numerous vital functions; however, some of the genes in these regions are non-vital. At such loci, hypomorphic mutants must represent intragenic alterations, and some viable nulls could conceivably be intra… more
Date: January 1, 1982
Creator: Russell, L.B.
Partner: UNT Libraries Government Documents Department
open access

Presence of UV-endonuclease sensitive sites in daughter DNA of UV-irradiated mammalian cells. [3H-thymidine tracer]

Description: Asynchronous Chinese hamster cells were irradiated with 10 Jm/sup -2/ uv radiation and 0.25 to 4 hours later pulse-labeled with (/sup 3/H)thymidine. Cells synchronized by shaking off mitotic and G/sub 1/ cells were irradiated in either the G/sub 1/-phase or S-phase of the cell cycle and pulse-labeled with (/sup 3/H)thymidine in the S-phase. After a 12 to 14 hour chase in unlabeled medium, the DNA was extracted, incubated with Micrococcus luteus uv-endonuclease and sedimented in alkaline sucrose… more
Date: February 1, 1978
Creator: D'Ambrosio, S. & Setlow, R.B.
Partner: UNT Libraries Government Documents Department
open access

UV action spectra for mammalian systems: their implications for the predicted effects of ozone depletion on skin cancer incidence

Description: The predicted environmental effect of UV-B depend on the action spectrum for the response studied. Since such spectra change rapidly - usually decreasing with increasing wavelength - and since the biological effects depend on the product of the action spectrum and the sun's spectrum at the surface of the earth which decreases with decreasing wavelength, a slight change in action spectrum will markedly influence the predicted effects of ozone depletion on biological systems. Thus, the key, but b… more
Date: January 1, 1982
Creator: Setlow, R.B.
Partner: UNT Libraries Government Documents Department
open access

Removal of uv-induced pyrimidine dimers from the replicated and unreplicated DNA of human fibroblasts

Description: Excision repair in uv irradiated human fibroblasts has been examined in portions of DNA replicating after irradiation versus those remaining unreplicated. Two approaches, one using a uv-endonuclease to estimate pyrimidine dimers remaining in DNA, the other using density labeling to measure excision resynthesis, indicate that the extent of repair is the same for both replicated and unreplicated DNA.
Date: January 1, 1978
Creator: Waters, R.
Partner: UNT Libraries Government Documents Department
open access

Distinction between the roles of O/sub 2/ and of O/sup -//sub 2/ in biological radiodamage

Description: The paper attempts to elucidate the roles of oxygen and superoxide radical in biological damage due to ionizing radiation. Specifically, the effect of gamma radiation on the survival of T4 bacteriophage and of E. coli B has been investigated. (ACR)
Date: January 1, 1978
Creator: Samuni, A.; Chevion, M.; Halpern, Y. S.; Ilan, Y. A. & Czapski, G.
Partner: UNT Libraries Government Documents Department
open access

Excision repair in mammalian cells. [uv radiation, N-acetoxy-2-acetylaminofluorene]

Description: Excision repair after combined treatments of uv and N-acetoxy-2-acetylaminofluorene (AAAF) was studied by three different techniques in cells proficient in uv excision repair and in cells deficient in uv repair. Two patterns of repair were observed: in repair proficient cells total repair was additive, and in repair deficient cells total repair was much less than additive--usually less than observed for separate treatments--and AAAF inhibited dimer excision. We conclude that in the 1st class of… more
Date: January 1, 1978
Creator: Ahmed, F.E. & Setlow, R.B.
Partner: UNT Libraries Government Documents Department
open access

Assessment of the response of spent fuel transports to malevolent acts

Description: This paper describes the results of a program conducted at Sandia National Laboratories (SNL) for the US Department of Energy to provide an experimental data base for more accurately assessing the radiological consequences from a hypothetical sabotage attack on a spent fuel shipping cask. The primary objectives of the program were limited to: (1) evaluating the effectiveness of selected high explosive devices (HED) in breaching full-size spent fuel casks, (2) quantifying and characterizing rele… more
Date: December 20, 1983
Creator: Sandoval, R.P.
Partner: UNT Libraries Government Documents Department
open access

Response of the Asiatic clam, Corbicula manilensis, to gamma radiation

Description: When heat exchangers for reactors were plugged by the Asiatic clam, acute gamma radiation was considered as a possible control. Clams were collected and sorted by size; during irradiation the clams were submerged in natural water. Clams of both sizes survived large doses with no radiation damage evident in 30 days. Mortality rose steeply at doses of 2.4 x 10/sup 4/ Rad and above; smaller clams showed a greater resistance than large ones. The feasibility of using periodic exposure to gamma radia… more
Date: January 1, 1977
Creator: Tilly, L. J.; Corey, J. C. & Bibler, N. E.
Partner: UNT Libraries Government Documents Department
open access

Problems in mechanistic theoretical models for cell transformation by ionizing radiation

Description: A mechanistic model based on yields of double strand breaks has been developed to determine the dose response curves for cell transformation frequencies. At its present stage the model is applicable to immortal cell lines and to various qualities (X-rays, Neon and Iron) of ionizing radiation. Presently, we have considered four types of processes which can lead to activation phenomena: (1) point mutation events on a regulatory segment of selected oncogenes, (2) inactivation of suppressor genes, … more
Date: October 1, 1991
Creator: Chatterjee, A. & Holley, W. R.
Partner: UNT Libraries Government Documents Department
open access

Utilization of critical periods during development to study the effects of low levels of environmental agents

Description: Careful definition of critical periods in the development of selected characters can result in experimental systems that may be highly useful in studying risk at low levels of exposure. Three examples are presented. Epidemiological investigations can lose much of their value unless critical periods are known for the end points being studied.
Date: January 1, 1980
Creator: Russell, L.B.
Partner: UNT Libraries Government Documents Department
open access

UV dose-effect relationships and current protection exposure standards

Description: In this paper we have attempted to quantify the health effects in man of uv-radiation exposure of wavelengths from 240 nm to 320 nm. Exposure to uv in this region could result in the formation of skin cancer or premature aging in man. The induction of cancer by uv radiation results from changes in genetic material. We have used the DNA action spectrum coupled with the uv skin cancer data available in the literature to derive the dose-effect relationships. The results are compared against the cu… more
Date: April 1, 1982
Creator: Singh, M.S. & Campbell, G.W.
Partner: UNT Libraries Government Documents Department
open access

The Toxicity of Inhaled Particles of Sup 238 PuO2 in Dogs

Description: This study was conducted to determine the toxicity of inhaled {sup 238}PuO{sub 2} in the dog. Inhalation was selected because it is the mostly likely route of human exposure in the event of an accidental airborne release. Of 166 dog in the study, 72 inhaled 1.5{mu}m and 72 inhaled 3.0 {mu}m activity median aerodynamic diameter particles of {sup 238}PuO{sub 2}. Another 24 dogs inhaled the aerosol vector without plutonium. The aerosol exposures resulted in initial pulmonary burdens ranging from 3… more
Date: January 1, 1991
Creator: Muggenburg, B. A.; Guilmette, R. A.; Griffith, W. C., (Jr.); Hahn, F. F.; Boecker, B. B. & Gillett, N. A.
Partner: UNT Libraries Government Documents Department
open access

DNA repair in human cells exposed to combinations of carcinogenic agents

Description: Normal human and XP/sup 2/ fibroblasts were treated with uv plus uv-mimetic chemicals. The uv dose used was sufficient to saturate the uv excision repair system. Excision repair after combined treatments was estimated by unscheduled DNA synthesis, BrdUrd photolysis, and the loss of sites sensitive to a uv specific endonuclease. Since the repair of damage from uv and its mimetics is coordinately controlled we expected that there would be similar rate-limiting steps in the repair of uv and chemic… more
Date: January 1, 1980
Creator: Setlow, R.B. & Ahmed, F.E.
Partner: UNT Libraries Government Documents Department
open access

Workshop on radiobiological effectiveness of neutrons

Description: 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… more
Date: September 1, 1985
Creator: Stapleton, G. E.; Thomas, R. G. & Thiessen, J. W.
Partner: UNT Libraries Government Documents Department
open access

Ultrastructural effects of radiation on cells and tissues: concluding remarks

Description: Concluding remarks which condense the subject matter covered in the preceding series of reports which indicate the complex nature of the biological response to ionizing radiation and the inherent difficulties associated with developing unifying concepts and definitions. The multiplicity of the major response variables, i.e., specimen type, radiation parameters, analytical approach and endpoints measured, is undoubtedly a major problem. In these studies, the specimens analyzed ranged from eucary… more
Date: January 1, 1982
Creator: Seed, T.M. & Carr, K.E.
Partner: UNT Libraries Government Documents Department
open access

Relating space radiation environments to risk estimates

Description: This lecture will provide a bridge from the physical energy or LET spectra as might be calculated in an organ to the risk of carcinogenesis, a particular concern for extended missions to the moon or beyond to Mars. Topics covered will include (1) LET spectra expected from galactic cosmic rays, (2) probabilities that individual cell nuclei in the body will be hit by heavy galactic cosmic ray particles, (3) the conventional methods of calculating risks from a mixed environment of high and low LET… more
Date: October 1, 1991
Creator: Curtis, S.B.
Partner: UNT Libraries Government Documents Department
open access

Mammary carcinogenesis in rats: basic facts and recent results in Brookhaven

Description: Some research results from experiments investigating neutron-induced mammary carcinogenesis in rats are presented. The additive effects of neutrons and 3-methylcholanthrene on mammary adenocarcinoma were determined. Synergism between diethylstilbestrol and neutrons was likewise studied. Differences in mammary neoplastic response between strains of laboratory rats was also investigated. (ACR)
Date: January 1, 1982
Creator: Shellabarger, C.J.; Stone, J.P. & Holtzman, s.
Partner: UNT Libraries Government Documents Department
open access

Low-exposure tritium radiotoxicity in mammals

Description: Studies of tritium radiotoxicity involving chronic /sup 3/H0H exposures in mammals demonstrate in both mice and monkeys that biological effects can be measured following remarkably low levels of exposure - levels in the range of serious practical interest to radiation protection. These studies demonstrate also that deleterious effects of /sup 3/H beta radiation do not differ significantly from those of gamma radiation at high exposures. In contrast, however, at low exposures tritium is signific… more
Date: February 11, 1982
Creator: Dobson, R.L.
Partner: UNT Libraries Government Documents Department
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