A large reduction of the ρ 0 mass in the nuclear medium is reported, inferred from dipion photopr... more A large reduction of the ρ 0 mass in the nuclear medium is reported, inferred from dipion photoproduction spectra in the 1 GeV region, for the reaction 3 He(γ,π + π -)X with a 10% duty factor tagged-photon beam and the TAGX multi-particle spectrometer. The energy range covered (800≤Eγ ≤1120 MeV) lies mostly below the free ρ 0 production threshold, a region which is believed sensitive to modifications of light vector-meson properties at nuclear-matter densities. The ρ 0 masses extracted from the MC fitting of the data, m * ρ 0 = 642±40, 669±32, and 682±56 MeV/c 2 for Eγ in the 800-880, 880-960, and 960-1040 MeV regions respectively, are independently corroborated by a measured, assumption-free, kinematical observable. This mass shift, far exceeding current mean-
Applied Biochemistry and Biotechnology, May 7, 2010
To understand the yeast response to high-linear energy transfer (LET) ionizing radiation (IR), we... more To understand the yeast response to high-linear energy transfer (LET) ionizing radiation (IR), we investigated global gene expression in yeast irradiated by three types of high-LET IR (fast neutrons, heavy ions, and thermal neutrons) and gamma rays using DNA microarray analysis. Stationary cells were irradiated by each IR and recultured in yeastpeptone-dextrose medium to allow repair for 40 min. RNA was then isolated from three independent samples of irradiated yeast. Genes involved in the Mec1p kinase pathway, which functions in DNA damage response, were induced by all forms of high-LET IR and by gamma rays. Some genes related to oxidative stress and the cell wall were induced by all forms of high-LET IRs. Gene expression patterns as a function of each type of high-LET IR were examined statistically by one-way analysis of variance. This analysis demonstrated the existence of irradiation-specific responses. For example, genes involved in ribosomal DNA synthesis were specifically induced by fast neutron irradiation, while the ubiquitinproteasome system and heat shock response were specifically induced by thermal neutron irradiation. The study characterizes high-LET IR-induced gene expression and provides a molecular understanding of subsequent adaptation in yeast.
Manganese-56 (56Mn) was one of the dominant neutron-activated radionuclides during the first hour... more Manganese-56 (56Mn) was one of the dominant neutron-activated radionuclides during the first hours following the atomic-bombing of Hiroshima and Nagasaki. The radiation spectrum of 56Mn and the radiation emission from excited levels of 56Fe following 56Mn beta-decay include gamma-quanta, beta-particles, Auger electrons and X-rays. The dispersion of neutron activated 56Mn in the air can lead to entering of radioactive microparticles into the lungs. The investigation of spatial microdistribution of an internal dose in biological tissue exposed to 56Mn is an important matter with regards to the possible elevated irradiation of the lung alveoli and alveolar ducts. The Monte Carlo code (MCNP-4C) was used for the calculation of absorbed doses in biological tissue around 56Mn dioxide microparticles. The estimated absorbed dose has a very essential gradient in the epithelium cells of lung alveoli and alveolar duct: from 61 mGy/decay on the surface of simple squamous cells of epithelium to 0.15 mGy/decay at distance of 0.3 μm, which is maximal cell thickness. It has been concluded that epithelial cells of these pulmonary microstructures are selectively irradiated by low-energy electrons: short-range component of beta-particles spectrum and Auger electrons. The data obtained are important for the interpretation of biological experiments implementing dispersed neutron-activated 56Mn dioxide powder.
Background: Human thyroid gland is generally regarded as a relatively low-risk organ in terms of ... more Background: Human thyroid gland is generally regarded as a relatively low-risk organ in terms of developing radiation-induced tumorigenesis. However, a rapid increase in the incidents of thyroid cancer after the Chernobyl nuclear reactor accident in 1986 provided additional insight into the risk of thyroid cancer. Three key risk factors have been identified to be involved in this increase: (1) internal irradiation from 131I fallout, (2) young age, and (3) a low-iodine diet. Our previous study demonstrated that the thyroid radiation dose was highest in the newborn rats fed with low-iodine diet when rats of varying ages were internally exposed to 131I at the same radioactivity per body weight. Objective: To examine the short-term effects of a low dose internal irradiation of 131I on the status of the thyroid hormone in rats of three different ages maintained on either standard diet or low-iodine diet. Methods: 131I was injected intraperitoneally in F344 rats at the ages of 1, 4, and 9 weeks. Animals were maintained with an iodine-deficient (IDD) or a standard (SD) diet. Changes in serum levels of triiodothyronine (T3), thyroxine (T4), and thyroid-stimulating hormone (TSH) were examined. Results: Dramatic changes in hormone levels were found only in the rats belonging to 1-week-old IDD group, in which T3 levels rapidly dropped and TSH levels increased after 131I irradiation, whereas they remained unchanged in the SD group. In 4- and 9-week-old rats, hormone levels were also steady after irradiation, with no differences between the IDD and SD groups. Conclusions: These data suggest that under low-iodine conditions, the status of thyroid hormone of newborn rats is particularly sensitive to internal irradiation of 131I.
were automatically shut down and all off-site power supplies were soon lost; however, emergency d... more were automatically shut down and all off-site power supplies were soon lost; however, emergency diesel generators started up and began to supply power. About 45 min after the earthquake, a tsunami with a height of 4-5 m above ground level (14-15 m above sea level) rushed toward areas deep within the plant site, resulting in the loss of all power sources except for one emergency diesel generator in Unit 6. With no means to control or cool the reactor units, the cores of Units 1-3 began to overheat because of the usual radioactive decay in the reactor. The fuel pool in Unit 4 also began to heat up because of the decay heat of the spent fuel. Efforts were made to maintain ventilation to reduce the increased pressure within the containment vessels of Units 1-3. However, severe damage to the fuel occurred, leading to melt-downs and/ or melt-throughs. In Units 1 and 3, and even in Unit 4, hydrogen explosions occurred on the top floors of the reactor buildings. As a result, large amounts of radionuclides, especially volatile radionuclides such as 131 I, 134 Cs, and 137 Cs were
h i g h l i g h t s ESR signals were examined in individual deciduous tooth enamel samples. The R... more h i g h l i g h t s ESR signals were examined in individual deciduous tooth enamel samples. The RIS sensitivity of deciduous teeth are similar with that in permanent teeth while its variation is larger. The BGS intensity of deciduous teeth are also similar with that in permanent teeth while its variation is also larger. The average of the line width of BGS in deciduous and permanent teeth are indistinguishable due to variation. The line position (g factors) of BGS in deciduous teeth is at slightly higher field than in permanent teeth. With these similarities and differences, ESR dosimetry with deciduous teeth will be also useful as with permanent teeth.
Introduction. Atrial septal defect (ASD) is an abnormal opening in the wall between the two atria... more Introduction. Atrial septal defect (ASD) is an abnormal opening in the wall between the two atrias of the heart. A catheter-based treatment in a heamodynamic room is a well established procedure. International literature has extremely limited data on related radiation dose levels. Purpose. To determine radiation dose (RD) fluoroscopy time (FT) and Number of images (I) in ASD treatment in both paediatric and adult patients in a major cardiosurgery center in Greece. Materials and methods. A sample of 161 patients were included in the study, divided in the following age categories: (1) 5-10 y, (2) 10-15 y, (3) 15-18;y and (4) >18 y. The X-ray machine used was a Siemens Artis Zee digital flat panel system. Various clinical (weight, body mass index, (BMI), etc.) and radiation related data (Kerma Area Product (KAP), fluoroscopy time (T) and number of images (F)) were recorded. Results. Median W (kg), BMI (kg/m 2), KAP (Gycm 2), T (min) and F for the 4 weight categories were:
Estimates of external absorbed dose in experimental animals exposed to sprayed neutron-activated ... more Estimates of external absorbed dose in experimental animals exposed to sprayed neutron-activated 56Mn powder are necessary for comparison with internal absorbed doses estimated under the same exposure conditions, which is required for a correct interpretation of the observed biological effects. It has been established that the measured dose of external absorbed dose as a result of gamma irradiation range 1–15 mGy, which is order of magnitude less than the maximal dose of internal gamma and beta irradiation of the whole body of the same experimental animals irradiated under the same conditions: according to the available literature data, the maximal values of absorbed dose of internal gamma-beta irradiation of the whole body are in the range of 330 mGy–1200 mGy for mice and 100 mGy–150 mGy for rats. It is concluded that under the conditions of experiments with dispersed neutron-activated powder 56MnO2, internal gamma-beta irradiation of experimental animals is the main factor of radiation exposure compared to external gamma irradiation.
The purpose of this study was to estimate the internal dose of radiation in Japanese macaques (ak... more The purpose of this study was to estimate the internal dose of radiation in Japanese macaques (aka Nihonzaru or snow monkey) due to the Fukushima nuclear power plant accident. Images of a male Japanese macaque weighing ~10 kg were acquired using a multi-slice computed tomography (CT) scan with a 64-row segment detector. The CT images were used to create voxel phantoms of the bones, bone marrow, brain, eyes, heart, lungs, stomach, liver, spleen, pancreas, kidneys, intestines, bladder, testes, thyroid and miscellaneous tissue. The Particle and Heavy Ion Transport System (PHITS) Monte Carlo code was used to calculate the internal exposure rate conversion factors for 134Cs, 137Cs and 131I isotopes for the created voxel phantoms with a statistical precision higher than 1%. The PHITS-calculated energy deposits were compared with those for rhesus monkeys. The results showed that the fractions of energy deposits for β-radiation in different organs were almost identical between the two speci...
Electron spin resonance (ESR) dosimetry was applied to human tooth enamel in order to obtain indi... more Electron spin resonance (ESR) dosimetry was applied to human tooth enamel in order to obtain individual absorbed doses for victims of the Hiroshima bomb who lived in the ‘black rain’ area. The so-called ‘black rain’ fell in the form of precipitation on the western part of Hiroshima city and the northwestern suburbs within a few hours after the explosion of the atomic bomb on 6 August 1945, and exposed the population in this area. Only three tooth samples were collected from this area. Since the teeth were located at positions 1, 2 and 4, only the lingual portion was used for the analysis. The results showed that the excess dose after subtracting natural radiation for one (position 4; hh1) was background, for the second (position 2; hh2) it was 133 mGy, and for the other (position 1; hh3) it was 243 mGy. Based on these results, we further investigated the radiation dose attributed to dental X-rays and head CT scan. Such dose of the hh3 radiographic examination was estimated to be 57–...
A large reduction of the ρ 0 mass in the nuclear medium is reported, inferred from dipion photopr... more A large reduction of the ρ 0 mass in the nuclear medium is reported, inferred from dipion photoproduction spectra in the 1 GeV region, for the reaction 3 He(γ,π + π -)X with a 10% duty factor tagged-photon beam and the TAGX multi-particle spectrometer. The energy range covered (800≤Eγ ≤1120 MeV) lies mostly below the free ρ 0 production threshold, a region which is believed sensitive to modifications of light vector-meson properties at nuclear-matter densities. The ρ 0 masses extracted from the MC fitting of the data, m * ρ 0 = 642±40, 669±32, and 682±56 MeV/c 2 for Eγ in the 800-880, 880-960, and 960-1040 MeV regions respectively, are independently corroborated by a measured, assumption-free, kinematical observable. This mass shift, far exceeding current mean-
Applied Biochemistry and Biotechnology, May 7, 2010
To understand the yeast response to high-linear energy transfer (LET) ionizing radiation (IR), we... more To understand the yeast response to high-linear energy transfer (LET) ionizing radiation (IR), we investigated global gene expression in yeast irradiated by three types of high-LET IR (fast neutrons, heavy ions, and thermal neutrons) and gamma rays using DNA microarray analysis. Stationary cells were irradiated by each IR and recultured in yeastpeptone-dextrose medium to allow repair for 40 min. RNA was then isolated from three independent samples of irradiated yeast. Genes involved in the Mec1p kinase pathway, which functions in DNA damage response, were induced by all forms of high-LET IR and by gamma rays. Some genes related to oxidative stress and the cell wall were induced by all forms of high-LET IRs. Gene expression patterns as a function of each type of high-LET IR were examined statistically by one-way analysis of variance. This analysis demonstrated the existence of irradiation-specific responses. For example, genes involved in ribosomal DNA synthesis were specifically induced by fast neutron irradiation, while the ubiquitinproteasome system and heat shock response were specifically induced by thermal neutron irradiation. The study characterizes high-LET IR-induced gene expression and provides a molecular understanding of subsequent adaptation in yeast.
Manganese-56 (56Mn) was one of the dominant neutron-activated radionuclides during the first hour... more Manganese-56 (56Mn) was one of the dominant neutron-activated radionuclides during the first hours following the atomic-bombing of Hiroshima and Nagasaki. The radiation spectrum of 56Mn and the radiation emission from excited levels of 56Fe following 56Mn beta-decay include gamma-quanta, beta-particles, Auger electrons and X-rays. The dispersion of neutron activated 56Mn in the air can lead to entering of radioactive microparticles into the lungs. The investigation of spatial microdistribution of an internal dose in biological tissue exposed to 56Mn is an important matter with regards to the possible elevated irradiation of the lung alveoli and alveolar ducts. The Monte Carlo code (MCNP-4C) was used for the calculation of absorbed doses in biological tissue around 56Mn dioxide microparticles. The estimated absorbed dose has a very essential gradient in the epithelium cells of lung alveoli and alveolar duct: from 61 mGy/decay on the surface of simple squamous cells of epithelium to 0.15 mGy/decay at distance of 0.3 μm, which is maximal cell thickness. It has been concluded that epithelial cells of these pulmonary microstructures are selectively irradiated by low-energy electrons: short-range component of beta-particles spectrum and Auger electrons. The data obtained are important for the interpretation of biological experiments implementing dispersed neutron-activated 56Mn dioxide powder.
Background: Human thyroid gland is generally regarded as a relatively low-risk organ in terms of ... more Background: Human thyroid gland is generally regarded as a relatively low-risk organ in terms of developing radiation-induced tumorigenesis. However, a rapid increase in the incidents of thyroid cancer after the Chernobyl nuclear reactor accident in 1986 provided additional insight into the risk of thyroid cancer. Three key risk factors have been identified to be involved in this increase: (1) internal irradiation from 131I fallout, (2) young age, and (3) a low-iodine diet. Our previous study demonstrated that the thyroid radiation dose was highest in the newborn rats fed with low-iodine diet when rats of varying ages were internally exposed to 131I at the same radioactivity per body weight. Objective: To examine the short-term effects of a low dose internal irradiation of 131I on the status of the thyroid hormone in rats of three different ages maintained on either standard diet or low-iodine diet. Methods: 131I was injected intraperitoneally in F344 rats at the ages of 1, 4, and 9 weeks. Animals were maintained with an iodine-deficient (IDD) or a standard (SD) diet. Changes in serum levels of triiodothyronine (T3), thyroxine (T4), and thyroid-stimulating hormone (TSH) were examined. Results: Dramatic changes in hormone levels were found only in the rats belonging to 1-week-old IDD group, in which T3 levels rapidly dropped and TSH levels increased after 131I irradiation, whereas they remained unchanged in the SD group. In 4- and 9-week-old rats, hormone levels were also steady after irradiation, with no differences between the IDD and SD groups. Conclusions: These data suggest that under low-iodine conditions, the status of thyroid hormone of newborn rats is particularly sensitive to internal irradiation of 131I.
were automatically shut down and all off-site power supplies were soon lost; however, emergency d... more were automatically shut down and all off-site power supplies were soon lost; however, emergency diesel generators started up and began to supply power. About 45 min after the earthquake, a tsunami with a height of 4-5 m above ground level (14-15 m above sea level) rushed toward areas deep within the plant site, resulting in the loss of all power sources except for one emergency diesel generator in Unit 6. With no means to control or cool the reactor units, the cores of Units 1-3 began to overheat because of the usual radioactive decay in the reactor. The fuel pool in Unit 4 also began to heat up because of the decay heat of the spent fuel. Efforts were made to maintain ventilation to reduce the increased pressure within the containment vessels of Units 1-3. However, severe damage to the fuel occurred, leading to melt-downs and/ or melt-throughs. In Units 1 and 3, and even in Unit 4, hydrogen explosions occurred on the top floors of the reactor buildings. As a result, large amounts of radionuclides, especially volatile radionuclides such as 131 I, 134 Cs, and 137 Cs were
h i g h l i g h t s ESR signals were examined in individual deciduous tooth enamel samples. The R... more h i g h l i g h t s ESR signals were examined in individual deciduous tooth enamel samples. The RIS sensitivity of deciduous teeth are similar with that in permanent teeth while its variation is larger. The BGS intensity of deciduous teeth are also similar with that in permanent teeth while its variation is also larger. The average of the line width of BGS in deciduous and permanent teeth are indistinguishable due to variation. The line position (g factors) of BGS in deciduous teeth is at slightly higher field than in permanent teeth. With these similarities and differences, ESR dosimetry with deciduous teeth will be also useful as with permanent teeth.
Introduction. Atrial septal defect (ASD) is an abnormal opening in the wall between the two atria... more Introduction. Atrial septal defect (ASD) is an abnormal opening in the wall between the two atrias of the heart. A catheter-based treatment in a heamodynamic room is a well established procedure. International literature has extremely limited data on related radiation dose levels. Purpose. To determine radiation dose (RD) fluoroscopy time (FT) and Number of images (I) in ASD treatment in both paediatric and adult patients in a major cardiosurgery center in Greece. Materials and methods. A sample of 161 patients were included in the study, divided in the following age categories: (1) 5-10 y, (2) 10-15 y, (3) 15-18;y and (4) >18 y. The X-ray machine used was a Siemens Artis Zee digital flat panel system. Various clinical (weight, body mass index, (BMI), etc.) and radiation related data (Kerma Area Product (KAP), fluoroscopy time (T) and number of images (F)) were recorded. Results. Median W (kg), BMI (kg/m 2), KAP (Gycm 2), T (min) and F for the 4 weight categories were:
Estimates of external absorbed dose in experimental animals exposed to sprayed neutron-activated ... more Estimates of external absorbed dose in experimental animals exposed to sprayed neutron-activated 56Mn powder are necessary for comparison with internal absorbed doses estimated under the same exposure conditions, which is required for a correct interpretation of the observed biological effects. It has been established that the measured dose of external absorbed dose as a result of gamma irradiation range 1–15 mGy, which is order of magnitude less than the maximal dose of internal gamma and beta irradiation of the whole body of the same experimental animals irradiated under the same conditions: according to the available literature data, the maximal values of absorbed dose of internal gamma-beta irradiation of the whole body are in the range of 330 mGy–1200 mGy for mice and 100 mGy–150 mGy for rats. It is concluded that under the conditions of experiments with dispersed neutron-activated powder 56MnO2, internal gamma-beta irradiation of experimental animals is the main factor of radiation exposure compared to external gamma irradiation.
The purpose of this study was to estimate the internal dose of radiation in Japanese macaques (ak... more The purpose of this study was to estimate the internal dose of radiation in Japanese macaques (aka Nihonzaru or snow monkey) due to the Fukushima nuclear power plant accident. Images of a male Japanese macaque weighing ~10 kg were acquired using a multi-slice computed tomography (CT) scan with a 64-row segment detector. The CT images were used to create voxel phantoms of the bones, bone marrow, brain, eyes, heart, lungs, stomach, liver, spleen, pancreas, kidneys, intestines, bladder, testes, thyroid and miscellaneous tissue. The Particle and Heavy Ion Transport System (PHITS) Monte Carlo code was used to calculate the internal exposure rate conversion factors for 134Cs, 137Cs and 131I isotopes for the created voxel phantoms with a statistical precision higher than 1%. The PHITS-calculated energy deposits were compared with those for rhesus monkeys. The results showed that the fractions of energy deposits for β-radiation in different organs were almost identical between the two speci...
Electron spin resonance (ESR) dosimetry was applied to human tooth enamel in order to obtain indi... more Electron spin resonance (ESR) dosimetry was applied to human tooth enamel in order to obtain individual absorbed doses for victims of the Hiroshima bomb who lived in the ‘black rain’ area. The so-called ‘black rain’ fell in the form of precipitation on the western part of Hiroshima city and the northwestern suburbs within a few hours after the explosion of the atomic bomb on 6 August 1945, and exposed the population in this area. Only three tooth samples were collected from this area. Since the teeth were located at positions 1, 2 and 4, only the lingual portion was used for the analysis. The results showed that the excess dose after subtracting natural radiation for one (position 4; hh1) was background, for the second (position 2; hh2) it was 133 mGy, and for the other (position 1; hh3) it was 243 mGy. Based on these results, we further investigated the radiation dose attributed to dental X-rays and head CT scan. Such dose of the hh3 radiographic examination was estimated to be 57–...
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