232 Matching Results

Search Results

Advanced search parameters have been applied.

in subjects: "Radiation Injuries"

open access

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

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.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

UV dose-effect relationships and current protection exposure standards

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.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Ultrastructural effects of radiation on cells and tissues: concluding remarks

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.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Radiation damage and its influence on source requirements for high resolution x-ray holography

Soft x-ray holography offers the possibility of obtaining high resolution, 3-D images of living cells and organelles therein. To achieve a specified resolution, a certain number of photons must be scattered by the smallest features of interest within the sample. This requires a certain irradiating fluence, the magnitude of which depends on the wavelength of the x rays and the scattering cross- sections of the features. Unfortunately, irradiation of the sample will be accompanied by the absorpti… more

Date: January 1, 1989

Creator: London, R. A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Feasibility of using sup 129 I concentrations in human tissue to estimate radiation dose from sup 131 I

To use data on {sup 129}I in human tissue to estimate an individual's past exposure to that radionuclide, it is necessary to know when and how the exposure occurred, and to know about any other prior and/or ongoing exposures. Moreover, to use {sup 129}I data to estimate past exposure to {sup 131}I, it is also necessary to know the relationship of the two radionuclides at the time of exposure. The relative quantities of {sup 131}I and {sup 129}I in gaseous effluents from Hanford Site facili… more

Date: October 1, 1989

Creator: McCormack, W.D.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Damage and repair of irradiated mammalian brain

We have demonstrated that focal charged particle irradiation of the rabbit brain can create well-defined lesions which are observable by nuclear magnetic resonance imaging (NMR) and positron emission tomography (PET) imaging techniques. These are similar, in terms of location and characteristic NMR and PET features, to those that occur in the brain of about 10% of clinical research human subjects, who have been treated for intracranial vascular malformations with stereotactic radiosurgery. Thes… more

Date: July 1, 1989

Creator: Frankel, K.; Lo, E.; Phillips, M.; Fabrikant, J.; Brennan, K.; Valk, P. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Spermatogonial stem cell renewal following irradiation

The spermatogonial cell renewal system can maintain function and a steady level of cell population for relatively long periods of continuous low-level irradiation indicating that there does not appear to be a serious accumulation, over many generations, of damage affecting proliferation. Provided the dose-rate is quite low, there is an effective selective removal of damaged cells with almost complete repair of cellular nonlethal damage. At dose-rates greater than 2 rad/day, spermatogonia are ve… more

Date: May 1, 1979

Creator: Fabrikant, Jacob I.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Laser protective eyewear program at the Los Alamos Scientific Laboratory

The proliferation of lasers at Los Alamos focused considerable attention on providing adequate eye protection for experimenters involved in the use of a wide variety of nonionizing radiation. Experiments with fast-pulsed lasers (Nd:YAG, HF, and CO/sub 2/) were performed to gain biological threshold data on ocular damage. In parallel, eye protection devices were evaluated, which resulted in the development of lightweight, comfortable spectacles of colored glass filters that can be ground to pres… more

Date: January 1, 1980

Creator: Winburn, D. C.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Effect of radiation quality and repair processes on the incidence of neoplastic transformation in vitro. [X radiation, mice]

Studies of the effect of radiation dose fractionation on survival of mammalian cells show that x-ray dose fractionation results in a substantial increase in net survival due to the rapid repair of sublethal damage. For high LET radiations, however, the magnitude of any net survival increase is appreciably less and may be essentially absent. Thus the capacity of cells to repair sublethal damage is an important factor in considering the effect of fractionation radiation exposure in the potential … more

Date: January 1, 1979

Creator: Han, A. & Elkind, M. M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Cells, targets, and molecules in radiation biology

Cellular damage and repair are discussed with regard to inactivation models, dose-effect curves and cancer research, repair relative to damage accumulation, potentially lethal damage, repair of potentially lethal vs. sublethal damage, cell killing and DNA damage due to nonionizing radiation, and anisotonicity vs. lethality due to nonionizing radiation. Other topics discussed are DNA damage and repair in cells exposed to ionizing radiation, kinetics of repair of single-strand DNA breaks, effects… more

Date: January 1, 1979

Creator: Elkind, M. M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Dosimetry of x-ray beams: The measure of the problem

This document contains the text of an oral presentation on dosimetry of analytical x-ray equipment presented at the Denver X-Ray Conference. Included are discussions of sources of background radiation, exposure limits from occupational sources, and the relationship of these sources to the high dose source of x-rays found in analytical machines. The mathematical basis of x-ray dosimetry is reviewed in preparation for more detailed notes on personnel dosimetry and the selection of the most approp… more

Date: August 1, 1986

Creator: de Castro, T.M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

In vitro enzymatic studies on the nature and repair of x-ray induced lesions in DNA

Areas studied include: purification and properties of enzyme probes for x-ray induced DNA lesions using E. Coli x-ray endonuclease and S. cerevisiae endonuclease E; use of enzymes probes; and use of physical, chemical and enzymatic probes to quantify x-ray-induced lesions in viruses and cells. (PCS)

Date: January 1, 1979

Creator: Wallace, S. S.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Ultraviolet-light-induced transformation of human primary cells

The development of model systems for probing the ultraviolet radiation induced oncogenic transformation of human skin cells is described. (ACR)

Date: January 1, 1981

Creator: Sutherland, B.M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Pacific Northwest Laboratory annual report for 1984 to the DOE Office of Energy Research. Part 4. Physical sciences

Progress is reported in the following areas: (1) chemical basis for the biological response to complex organic mixtures; (2) supercritical fluid analytical methods; (3) lasers in analytical chemistry; (4) initial interaction processes in radiation physics; (5) track structure; (6) radiation dosimetry; (7) modeling and cellular studies; (8) radiation biophysics; (9) modeling cellular response to genetic damage; and (10) internal microdosimetry. (ACR)

Date: February 1, 1985

Creator: Danko, J.E. (ed.)

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Radioactive fallout

Potential radiation doses from several scenarios involving nuclear attack on an unsheltered United States population are calculated for local, intermediate time scale and long-term fallout. Dose estimates are made for both a normal atmosphere and an atmosphere perturbed by smoke produced by massive fires. A separate section discusses the additional doses from nuclear fuel facilities, were they to be targeted in an attack. Finally, in an appendix the direct effects of fallout on humans are consi… more

Date: December 1, 1985

Creator: Shapiro, C. S.; Harvey, T. F. & Peterson, K. R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

What Has Happened to the Survivors of the Early Los Alamos Nuclear Accidents?

Abstract: Two nuclear accidents involving a plutonium sphere just subcritical in size occurred at the Los Alamos Laboratory, LA-1 in 1945 and LA-2 in 1946. Because remote control devices were deemed unreliable at the time, the tamper material (tungsten carbide bricks in LA-1 and beryllium hemispheres in LA-2) was added by hand with the operator standing next to the assembly. In each case the critical size of the assembly was accidentally exceeded and the resultant exponentially increasing chain… more

Date: 1979

Creator: Hempelman, Louis Henry; Lushbaugh, Clarence C. & Voelz, George L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Repair of ultraviolet-light-induced damage

Studies are reviewed which present three major new findings in the photobiology of skin. First, detectable numbers of dimers are formed even at sub-erythymal doses. Second, excision of dimers is much more rapid than would be predicted from results obtained in cell culture. Third, comparison of the rates of excision and photoreactivation in skin indicates that in normal sunlight exposure, photoreactivation may well be the predominant repair pathway in skin. (ACR)

Date: January 1, 1981

Creator: Sutherland, B.M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Environmental and biological behaviour of plutonium and some other transuranium elements

The objectives are to summarize our knowledge of the way in which plutonium and some other transuranium elements migrate through ecosystems; to consider how the physiochemical state of these elements and the biological systems through which they pass may influence this movement; and to put into perspective the risks of serious illness in man resulting from his exposure to these elements in the environment.

Date: April 7, 1983

Creator: Richmond, C.R.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Effects of x-irradiation on lens reducing systems. [Rabbits]

Studies have been made of the effects of x ray on various lens reducing systems including the levels of NADPH and glutathione (GSH), the activity of the hexose monophosphate shunt (HMS), and the activities of certain enzymes including glutathion reductase, glutathione peroxidase, and glucose-6-phosphate dehydrogenase (G-6-PD). It was found that during several weeks following x irradiation but prior to cataract formation there was very little change in the number of reduced -SH groups per unit w… more

Date: January 1, 1978

Creator: Giblin, F. J.; Chakrapani, B. & Reddy, V. N.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Possibilities and problems in uv radiation carcinogenesis experiments

Experiments were designed to solve problems in dose-response relationships in uv-induced carcinogenesis. Two strains of hairless mice were exposed to 300 to 400 nm, 320 to 400 nm, and 365 nm wavelength emissions following exposure to 8-methoxy-psoralen; various fractionation regimes were used. Results showed that the number of psoralen-DNA crosslinks per cell increased linearly with dose. The importance of wavelength in the initiation and the expression of tumors is emphasized. (HLW)

Date: January 1, 1978

Creator: Fry, R.J.M.; Ley, R.D. & Grube, D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Oxygen effects in radiation biology and radiation chemistry

The question of the influence of O/sub 2/ on the radiation sensitivity of organisms, cells and biomolecules is reviewed. Evidence is presented to show that there are two mechanisms that govern the manner in which O/sub 2/ acts in cells. It is also suggested that these may in addition be other mechanisms but no evidence is presented to support this. (ACR)

Date: January 1, 1979

Creator: Powers, E. L. & Held, K. D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

The economic costs of radiation-induced health effects: Estimation and simulation

This effort improves the quantitative information available for use in evaluating actions that alter health risks due to population exposure to ionizing radiation. To project the potential future costs of changes in health effects risks, Pacific Northwest Laboratory (PNL) constructed a probabilistic computer model, Health Effects Costs Model (HECOM), which utilizes the health effect incidence estimates from accident consequences models to calculate the discounted sum of the economic costs assoc… more

Date: August 1988

Creator: Nieves, L. A. & Tawil, J. J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Photoreactivation in bacteria and in skin

In many procaryotic and eucaryotic cells, photoreactivating enzyme mediates light-dependent repair of uv-induced damage; the enzyme binds to a pyrimidine dimer in DNA, and, on absorption of a photon (300 to 600 nm), specifically monomerizes the dimer, thus repairing the DNA. Photoreactivating enzyme has been found in human tissues and human cells in culture can photoreactivate cellular dimers, and can mediate photoreactivation of Herpes (human fibroblasts) and Epstein-Barr virus (human leukocyt… more

Date: January 1, 1980

Creator: Sutherland, B. M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Mechanisms for radiation damage in DNA, Progress report, November 1, 1977--October 31, 1978. [Gamma radiation]

In this project we have proposed several mechanisms for radiation damage to DNA constituents and DNA, and have detailed a series of experiments utilizing electron spin resonance spectrometry to test the proposed mechanisms. In the past we have concentrated chiefly on the direct affect of radiation on DNA. We are currently investigating systems of DNA constituents and peptides which may shed light on indirect effects. Studies which we have completed during the past year are: ..pi..-cation radica… more

Date: June 1, 1978

Creator: Sevilla, M. D.

Item Type: Report

Partner: UNT Libraries Government Documents Department