Abstract：
:Hematoporphyrin (Hp) solutions were subjected to a wide range high intensity (0.2-10.0 GW/cm2) near-UV laser pulse radiation (lambda exc = 355 nm, pulse duration 30 ps). The formation of stable Hp photoproducts was followed by UV-VIS absorption spectroscopy and liquid-gel column chromatography. As judged by the influence of free radial scavengers, a significant part of the products is assigned to arise from the reaction of Hp with OH.(and H.) radicals. Using nitroxide radicals (TEMPO and TEMPONE) and the spin trap DMPO the generation of primary transient photoproducts, hydrated electrons (eaq-), OH. and H. radicals, was studied varying the pulse intensity at a constant absorbed light energy. The results showed that bi-photonic processes are responsible for the observed product generation (different for eaq- photoejection and OH.(H.) formation). A tentative diagram of the Hp excitation routes involved in the present high intensity laser flash photolysis is suggested. According to it, OH. and H. radicals are supposed to be generated in a resonance energy transfer reaction from highly excited Hp** to water molecules (H2O sensitization).
journal_name
Radiat Environ Biophysjournal_title
Radiation and environmental biophysicsauthors
Gantchev T,Keskinova E,Kaltchev M,Angelov Ddoi
10.1007/BF01210525subject
Has Abstractpub_date
1990-01-01 00:00:00pages
225-39issue
3eissn
0301-634Xissn
1432-2099journal_volume
29pub_type
杂志文章abstract：:Within the Theory of Dual Radiation Action, the heuristically useful function, gamma(chi), that two energy depositions, a distance chi apart, will result in observable damage can be written in terms of two more fundamental quantities: One, s(chi), describes the structure of the sensitive matrix of the cell. The other,...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/BF01210836
更新日期：1988-01-01 00:00:00
abstract：:We examined, by the fluorescent halo assay, alterations in the nucleoid structure (structure formed from cells under mild lysis conditions: in non-ionic detergent Triton X-100, 0.0005% and 1.5 mol/l NaCl) of L5178Y (LY) cell sublines which had been untreated, treated with reducing/chelating agents (beta-mercaptoethano...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/BF01210211
更新日期：1992-01-01 00:00:00
abstract：:The radiation-induced process of strand breaks on pBR322 plasmid DNA in aqueous solution for different energy electrons was studied by Monte Carlo simulation. Assumptions of induction mechanisms of single- and double-strand breaks (SSBs and DSBs) used in the simulation are that SSB is induced by OH or H reaction with ...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/s00411-002-0161-8
更新日期：2002-09-01 00:00:00
abstract：:Beginning in 1950, people living on the banks of the Techa River received chronic low-dose-rate internal and external radiation exposures as a result of releases from the Mayak nuclear weapons plutonium production facility in the Southern Urals region of the Russian Federation. The Techa River cohort includes about 30...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/s00411-009-0257-5
更新日期：2010-05-01 00:00:00
abstract：:Responses of the S/S variant of the L5178Y murine leukemic lymphoblast, the photoreceptor cell of the rabbit retina and the lenticular epithelium of the rabbit to heavy ions (20Ne, 28Si, 40Ar and 56Fe) are described and discussed primarily from the standpoint of the need for a comprehensive theory of cellular radiosen...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/BF01209679
更新日期：1986-01-01 00:00:00
abstract：:The migration of radionuclides from waste repositories to the biosphere potentially leads to a contamination of soil. Due to the importance of food production, the mobilisation and accumulation behaviour of long-lived radionuclides in the soil plays a key role in performance assessment studies. In this paper, the main...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章,评审
doi：10.1007/s004110100098
更新日期：2001-06-01 00:00:00
abstract：:It is shown by UV absorption and absolute fluorescence spectroscopy of solutions containing both DNA and quinacrine that the components experience mutual radio-protection due to scavenging of water radicals. From measurements at different ionic strengths it is inferred that quinacrine bound to DNA is more efficiently ...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/BF02339804
更新日期：1975-06-13 00:00:00
abstract：:Preliminary results on the spectral dependence of the absorption of light in tissue are presented and discussed with respect to medical laser application. ...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/BF01323942
更新日期：1977-10-12 00:00:00
abstract：:Investigation of cell-free DNA (cf-DNA) in body fluids, as a potential biomarker for assessing the effect of ionizing radiation on the organism, is of considerable interest. We investigated changes in the contents of cell-free mitochondrial DNA (cf-mtDNA) and cell-free nuclear DNA (cf-nDNA) in the urine of X-ray-expos...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/s00411-015-0599-0
更新日期：2015-08-01 00:00:00
abstract：:Our recent results suggest that 50 Hz magnetic fields (MF) enhance ultraviolet (UV)-induced tumorigenesis in mouse skin. The aim of the present experiment was to study suppression of apoptosis as a possible mechanism for MF effects on skin tumorigenesis. Another aim was to test the importance of a UV and MF exposure s...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/s00411-002-0153-8
更新日期：2002-06-01 00:00:00
abstract：:In the mountainous "Hohe Tauern" region of Salzburg (Austria), milk samples have been collected in a long-term montitoring programme since 1988, at eight alpine sites used for extensive, seasonal stock farming. For this alpine environment with its acidic soils developed on silicate bedrock, high soil-to-plant transfer...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/s00411-008-0192-x
更新日期：2009-02-01 00:00:00
abstract：:Combined action of irradiation (IR), shear stress, and high blood pressure is well recognized to induce damage to vasculature, while data on pathological effects of IR in large peripheral vessels with low blood pressure are scarce. The purpose of the present study was hence to investigate time- and dose-dependent effe...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/s00411-013-0492-7
更新日期：2014-03-01 00:00:00
abstract：:The non-random distribution of DNA breakage in pulsed-field gel electrophoresis (PFGE) experiments poses a problem of proper subtraction of the background damage to obtain a fragment-size distribution due to radiation only. As been pointed out by various authors, a naive bin-to-bin subtraction of the background signal...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/s00411-007-0098-z
更新日期：2007-06-01 00:00:00
abstract：:Working from the general postulate that natural selection of plant form operates so as to maximize the survival potential of a species, this paper examines the hypothesis that the mechanical support of tree foliage must approach optimality in the use of wood, i.e., that tree stems and branches will have "optimal form"...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/BF01323263
更新日期：1978-08-10 00:00:00
abstract：:A Monte Carlo model is presented to study details of the energy deposition inside tracks of heavy charged particles in water vapor. The input data for most of the calculations based on the binary encounter approximation are double-differential cross sections for electron emission after heavy-ion impact. The paths of t...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章,评审
doi：10.1007/BF01219334
更新日期：1994-01-01 00:00:00
abstract：:The observable responses of living systems to ionizing radiation depend on the level of biological organization studied. Understanding the relationships between the responses characteristic of the different levels of organization is of crucial importance. The main objective of the present study is to investigate how s...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/s00411-011-0382-9
更新日期：2011-11-01 00:00:00
abstract：:The rate constants for the photodynamic inactivation of hen egg-white lysozyme at different temperatures were studied. Arrhenius plots of the methylene blue sensitized photo-inactivation of lysozyme gave an experimental activation energy of 7.5 kcal/mol. The rate constants for the photodynamic inactivation of lysozyme...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/BF01326898
更新日期：1979-02-23 00:00:00
abstract：:In this study, temporal variations of indoor radon concentrations in Bulgaria were investigated. The radon concentrations were measured by nuclear track detectors as part of the Bulgarian National Survey, performed in the dwellings of 28 regional districts. The detectors were exposed through a year in two consecutive ...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/s00411-019-00789-y
更新日期：2019-08-01 00:00:00
abstract：:A human total-body counter was designed and built with two 20 X 10 cm NaI (Tl) crystals suspended over an "isoresponse surface" upon which the subject reclines. This surface is curved from head to knee and from left to right, so that a gamma-ray emitting object is detected with equal efficiency when placed anywhere up...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/BF01323223
更新日期：1979-04-30 00:00:00
abstract：:The relationship between occupational exposure to extremely low-frequency electromagnetic fields and adult leukaemia has been studied extensively during the last decade. The first studies were based on crude exposure assessments, estimated through job titles, with no or only limited control confounding factors. The re...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章,评审
doi：10.1007/s004110050036
更新日期：1996-11-01 00:00:00
abstract：:Time-dependent yields of the most important products of water radiolysis E(aq)(-), (*)OH, H(*), H(3)O(+), H(2), OH(-) and H(2)O(2) have been calculated for (60)Co-photons, electrons, protons, helium- and carbon-ions incident onto water. G values have been evaluated for the interval from 1 ps to 1 mus after initial ene...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/s00411-008-0194-8
更新日期：2009-02-01 00:00:00
abstract：:Data on rats exposed to cigarette smoke before or after exposure to radon are used to estimate smoke-dependent parameters of the biologically based two-stage clonal expansion model. The baseline parameters and the action of radon acting on initiation and promotion were fixed based on earlier work. Cigarette smoke acti...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/s00411-005-0006-3
更新日期：2005-10-01 00:00:00
abstract：:Blue (F450) and green (F530) leaf fluorescence were studied together with the red chlorophyll fluorescence (emission maxima F690 and F735) during light-induced chlorophyll fluorescence induction kinetics (Kautsky effect) in predarkened leaves of wheat (Triticum aestivum L.) and soybean (Glycine max L.). The intensity ...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/BF01225923
更新日期：1993-01-01 00:00:00
abstract：:In this work, direct DNA damage induced by low-energy electrons (<5 keV) is simulated using Monte Carlo methods, and the resulting yield of various strand breaks and base damages in cellular environment is presented. The simulation is based on a new inelastic cross section for the production of electron track structur...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/s00411-009-0262-8
更新日期：2010-03-01 00:00:00
abstract：:The effect of gamma radiation on red blood cells have been examined using a spin labeling method. For this purpose two spin labels were used to monitor membrane fluidity: methyl 5-doxylpalmitate (Met 5-DP) and methyl 12-doxylstearate (Met 12-DS). The irradiation of red cells with the doses of 200 and 500 Gy caused dec...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/BF01595573
更新日期：1991-01-01 00:00:00
abstract：:Radiation is known to be carcinogenic to humans but attempts to demonstrate the process using human tissue culture models have met with little success. In the present study explants were established from urothelium and exposed to radiation and a range of chemical carcinogens, suspected promotor or metabolic agents. Th...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/BF01210524
更新日期：1990-01-01 00:00:00
abstract：:Radiological impact assessment for flora and fauna requires adequate dosimetric data. Due to the variability of habitats, shapes, and masses of the non-human biota, assessment of doses is a challenging task. External and internal dose conversion coefficients for photons and electrons have been systematically calculate...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/s00411-006-0061-4
更新日期：2006-09-01 00:00:00
abstract：:Within the track structure code PARTRAC, DNA strand break induction by direct and indirect radiation action was calculated for the E. coli catabolite gene activator protein (CAP) DNA complex with (125)I located at the position of the H(5) atom of the cytosine near the center. The shape of the resulting DNA fragment si...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/s00411-004-0231-1
更新日期：2004-05-01 00:00:00
abstract：:To explore possible applications of iodoacetate (IA), a glycolytic inhibitor, in cancer treatment, we screened its cytotoxicity and radioprotective/sensitizing efficacy in three different mammalian cell lines; A549 (human lung carcinoma), MCF7 (human mammary cancer), a non-cancerous CHO (Chinese hamster ovary) cells a...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/s00411-017-0699-0
更新日期：2017-08-01 00:00:00
abstract：:The potential of naturally occurring antioxidants to reduce the cellular oxidative damage induced by ionizing radiation has been studied for more than a decade for their pharmacological application during cancer treatment. It is already known that radioprotective efficacy of phytochemicals might influence various end ...
journal_title：Radiation and environmental biophysics
pub_type： 杂志文章
doi：10.1007/s00411-014-0551-8
更新日期：2014-11-01 00:00:00
