共查询到20条相似文献,搜索用时 31 毫秒
1.
Qi Wang Monica Pujol-Canadell Maria Taveras Guy Garty Jay Perrier Carlos Bueno-Beti Igor Shuryak David J. Brenner Helen C. Turner 《Radiation and environmental biophysics》2020,59(1):89-98
Environmental contamination and ingestion of the radionuclide Cesium-137 (137Cs) is a large concern in fallout from a nuclear reactor accident or improvised nuclear device, and highlights the need to develop biological assays for low-dose rate, internal emitter radiation. To mimic low-dose rates attributable to fallout, we have developed a VAriable Dose-rate External 137Cs irradiatoR (VADER), which can provide arbitrarily varying and progressive low-dose rate irradiations in the range of 0.1–1.2 Gy/day, while circumventing the complexities of dealing with radioactively contaminated biomaterials. We investigated the kinetics of mouse peripheral leukocytes DNA damage response in vivo after variable, low-dose rate 137Cs exposure. C57BL/6 mice were placed in the VADER over 7 days with total accumulated dose up to 2.7 Gy. Peripheral blood response including the leukocyte depletion, apoptosis as well as its signal protein p53 and DNA repair biomarker γ-H2AX was measured. The results illustrated that blood leukocyte numbers had significantly dropped by day 7. P53 levels peaked at day 2 (total dose = 0.91 Gy) and then declined; whereas, γ-H2AX fluorescence intensity (MFI) and foci number generally increased with accumulated dose and peaked at day 5 (total dose = 2.08 Gy). ROC curve analysis for γ-H2AX provided a good discrimination of accumulated dose < 2 Gy and ≥ 2 Gy, highlighting the potential of γ-H2AX MFI as a biomarker for dosimetry in a protracted, environmental exposure scenario. 相似文献
2.
Jorge Ramrez-Franco Rigoberto Oros-Pantoja Eugenio Torres-Garca Liliana Aranda-Lara Luis E. Daz-Snchez Claudia I. Herrera-Ayala Elvia Prez-Soto Erika P. Azorn-Vega 《Radiation and environmental biophysics》2020,59(2):257-263
The aim of this work is to determine the effect of chronic immobilization stress on kinetics and dosimetry of 67Ga in a mouse model. A control group (CG) and a stress group (SG), each with 15 mice, were included in the study, and the latter group was subjected to a chronic immobilization stress model 2 h daily for 14 consecutive days. At day 13, 67Ga-citrate was administered intraperitoneally (11.24 ± 0.44 MBq) to each mouse. Then, sets of three mice were obtained sequentially at 24, 36, 48, 60 and 72 h, in which the radionuclide activity was measured with an activity counter. The 67Ga biokinetic data showed a fast blood clearance in the SG, with a mean residence time of 0.06 h. The calculated mean radiation absorbed doses were: liver (2.45 × 10−03 Gy), heart (3.17 × 10−04 Gy) and kidney (1.88 × 10−04 Gy) in the SG. The results show that stress reduced weight gain by approximately 13% and also increased adrenal gland weight by 26%. On the other hand, chronic stress accelerates 67Ga clearance after 24 h compared to normal conditions. It is concluded that murine organisms under chronic immobilization stress have higher gallium-67 clearance rates, decreasing the cumulated activity and absorbed dose in all organs. 相似文献
3.
Vasin M. V. Ushakov I. B. Kovtun V. Yu. Komarova S. N. Semenova L. A. Koroleva L. V. Galkin A. A. Afanas’ev R. V. 《Biophysics》2011,56(5):917-920
Hybrid F1 mice (CBA × C57Bl/6) were subjected to irradiation at a nonlethal dose of 6.7 Gy that brought on acute radiation
sickness. In the experiments performed, we observed the beneficial effect of combined application of quercetin injected 30–60
min prior to irradiation with γ rays and the emergent radioprotector indralin injected after irradiation on development of
postradiation repair in hematopoietic tissue. This effect was expressed as accelerated formation of endogenous spleen colonies
and recovery of spleen weight and attenuation of leucopenia 12 and 16 days after acute irradiation. Treatment with only quercetin
was not radioprotective. 相似文献
4.
To date, there is scant information on in vivo induction of chromosomal damage by heavy ions found in space (i.e. 56Fe ions). For radiation-induced response to be useful for risk assessment, it must be established in in vivo systems especially
in cells that are known to be at risk for health problems associated with radiation exposure (such as hematopoietic cells,
the known target tissue for radiation-induced leukemia). In this study, the whole genome multicolor fluorescence in situ hybridization
(mFISH) technique was used to examine the in vivo induction of chromosomal damage in hematopoietic tissues, i.e. bone marrow
cells. These cells were collected from CBA/CaJ mice at day 7 following whole-body exposure to different doses of 1 GeV/amu
56Fe ions (0, 0.1, 0.5 and 1.0 Gy) or 137Cs γ rays as the reference radiation (0, 0.5, 1.0 and 3.0 Gy, at the dose rate of 0.72 Gy/min using a GammaCell40). These
radiation doses were the average total-body doses. For each radiation type, there were four mice per dose. Several types of
aberrations in bone marrow cells collected from mice exposed to either type of radiation were found. These were exchanges
and breaks (both chromatid- and chromosome-types). Chromosomal exchanges included translocations (Robertsonian or centric
fusion, reciprocal and incomplete types), and dicentrics. No evidence of a non-random involvement of specific chromosomes
in any type of aberrations observed in mice exposed to 56Fe ions or 137Cs γ rays was found. At the radiation dose range used in our in vivo study, the majority of exchanges were simple. Complex
exchanges were detected in bone marrow cells collected from mice exposed to 1 Gy of 56Fe ions or 3 Gy of 137Cs γ rays only, but their frequencies were low. Overall, our in vivo data indicate that the frequency of complex chromosome
exchanges was not significantly different between bone marrow cells collected from mice exposed to 56Fe ions or 137Cs γ rays. Each type of radiation induced significant dose-dependent increases (ANOVA, P < 0.01) in the frequencies of chromosomal damage, including the numbers of abnormal cells. Based upon the linear-terms of
dose-response curves, 56Fe ions were 1.6 (all types of exchanges), 4.3 (abnormal cells) and 4.2 (breaks, both chromatid- and chromosome-types) times
more effective than 137Cs γ rays in inducing chromosomal damage. 相似文献
5.
Kanokporn Noy Rithidech Paiboon Reungpatthanaphong Louise Honikel Adam Rusek Sanford R. Simon 《Radiation and environmental biophysics》2010,49(3):405-419
The objective of this study was to determine the kinetics of nuclear factor-kappa B (NF-κB) activation and cytokine expression
in bone marrow (BM) cells of exposed mice as a function of the dose rate of protons. The cytokines included in this study
are pro-inflammatory [i.e., tumor necrosis factor-alpha (TNF-α), interleukin-1beta (IL-1β), and IL-6] and anti-inflammatory
cytokines (i.e., IL-4 and IL-10). We gave male BALB/cJ mice a whole-body exposure to 0 (sham-controls) or 1.0 Gy of 100 MeV
protons, delivered at 5 or 10 mGy min−1, the dose and dose rates found during solar particle events in space. As a reference radiation, groups of mice were exposed
to 0 (sham-controls) or 1 Gy of 137Cs γ rays (10 mGy min−1). After irradiation, BM cells were collected at 1.5, 3, 24 h, and 1 month for analyses (five mice per treatment group per
harvest time). The results indicated that the in vivo time course of effects induced by a single dose of 1 Gy of 100 MeV protons
or 137Cs γ rays, delivered at 10 mGy min−1, was similar. Although statistically significant levels of NF-κB activation and pro-inflammatory cytokines in BM cells of
exposed mice when compared to those in the corresponding sham controls (Student’s t-test, p < 0.05 or <0.01) were induced by either dose rate, these levels varied over time for each protein. Further, only a dose rate
of 5 mGy min−1 induced significant levels of anti-inflammatory cytokines. The results indicate dose-rate effects of protons. 相似文献
6.
Helal Ragab Moussa 《Russian Journal of Plant Physiology》2006,53(2):193-197
The changes in the growth indices and certain metabolic activities in response to different doses of γ-irradiation (0, 20,
50, 100, and 200 Gy) were studied, using rocket seedlings. The total yield, seed mass, and essential oil content increased
significantly by 20 Gy dose of γ-irradiation as compared with the control samples. In addition, total sugars, total free amino
acids, total soluble phenols, kinetin, GA3, nitrate reductase activity, and total protein increased significantly at 20 Gy dose. Meanwhile, NO3 content decreased significantly at 20 Gy dose. The nitrogen and potassium content increased at the same dose of gamma rays
of 20 Gy. While the phosphorus content showed no significant effect at all the γ-irradiation doses used. The results obtained
in this work revealed that the most effective dose was 20 Gy of gamma rays. It was suggested that pretreatment of rocket seeds
before planting with 20 Gy dose of γ-irradiation, may oppose the harsh effect of NO3 accumulation and increased the quality and quantity of rocket yield.
Published in Russian in Fiziologiya Rastenii, 2006, Vol. 53, No. 2, pp. 215–219.
The text was submitted by the author in English. 相似文献
7.
Lees CJ Apostolopoulos V Acres B Ong CS Popovski V McKenzie IF 《Cancer immunology, immunotherapy : CII》2000,48(11):644-652
MUC1 is a mucin over-expressed in breast cancer and a proposed target for immunotherapy. By immunising mice with MUC1 conjugated
to mannan (M-FP), CD8+ MHC-class-I restricted cytotoxic T lymphocytes (CTL), of high CTL precursor (CTLp) frequency (1/8000) and with significant
tumour protection, can be induced. The effect of various cytokines [interleukin-2 (IL-2), IL-4, IL-6, IL-7, interferon γ (IFNγ),
and granulocyte/macrophage-colony-stimulating factor (GM-CSF)] on the MUC1 CTL immune response was investigated (a) by measuring
the frequencies of CTLp in mice immunised with vaccinia virus constructs containing recombinant cytokines and M-FP, or (b)
by immunising cytokine- or cytokine-receptor-knockout (−/−) mice with M-FP. Vaccinia virus (VV) constructs containing recombinant
cytokines were used either individually or in combination in vivo with M-FP immunisation. M-FP immunisations combined with
VV-IL-2, VV-IL-7 and VV-GM-CSF, and combinations of VV-IFNγ + VV-IL-2, VV-IFNγ + VV-IL-4 or VV-GM-CSF + VV-IL-7 increased
CTLp frequencies up to threefold (1/17 666: M-FP + VV-GM-CSF + VV-IL-7) compared to M-FP (1/77 500) alone. By contrast, M-FP
combined with VV-IL-4 decreased the CTLp frequency threefold whereas VV-IL-6 and VV-IFNγ had no effect. Studies in cytokine-
and cytokine-receptor-gene-knockout (−/−) mice demonstrated that mice that are IL-2 −/− and IL-7 receptor −/− produce the
same CTLp response to M-FP as do control mice, whereas responses in the IL-6 −/−, IL-10 −/− and IFNγ−/− mice were marginally
improved and responses to M-FP in IL-4 −/− and tumour necrosis factor receptor 2 −/− mice were weaker. In spite of the increase
in CTLp frequency, this was not reflected in an in vivo tumour model. Tumour challenges using MUC1+ P815 cells, demonstrated that the addition of cytokines had little additive effect on the already effective tumour-regression
capabilities of M-FP alone.
Received: 24 September 1998 / Accepted: 21 September 1999 相似文献
8.
The effect of combined action of cadmium chloride at a dose of 0.5 mg/kg of body weight and γ-radiation of 1 Gy on induction
of DNA damage in thymocytes and the total number of cells in the thymus of mice was studied. We found that injection of CdCl2 0.5 h prior to irradiation decreased the number of single-strand DNA breaks and the number of alkali-labile sites in thymocytes
48 h after irradiation as compared to the γ-radiation effect only. This effect was associated with a strong decrease in the
total number of thymocytes in this organ as compared to the action of cadmium ions and γ radiation separately. This masked
the general genotoxic effect of combined treatment and created an illusion of a radioprotective effect of cadmium ions. Injection
of cadmium chloride into mice 24 h prior to irradiation was followed by an additive increase in the number of the single-strand
DNA breaks and the number of alkali-labile sites in thymocytes as compared to the respective controls such as the separate
effects of cadmium ions and irradiation. We revealed a simultaneous decrease in the part of DNA tightly bound to proteins,
i.e., DNA-protein cross-links as compared to the effect of γ-radiation only. We did not observe any statistically significant
changes in the total number of thymocytes as compared to the separate effects of cadmium ions and irradiation. Thus, our data
show that exposure of murine thymocytes to combined action of cadmium ions and γ-radiation at the doses and with the methods
of treatment used induced additive effects but not antagonistic effects or protection against radiation. 相似文献
9.
V. A. Tronov Yu. V. Vinogradova M. Yu. Loginova V. A. Poplinskaya M. A. Ostrovsky 《Cell and Tissue Biology》2012,6(3):219-227
Retinopathy of animals is induced by many DNA-damaging agents. This fact shows that DNA lesions may initiate retinal degeneration.
The aim of our work was to study the effects of gamma and proton irradiation and single administration of methylnitrosourea
(MNU) on mice retina. We assessed morphological changes, DNA damage and repair, as well as expression of proteins (p53, ATM,
PARP, FasR, and caspase 3) participating in apoptosis in retina. 14 Gy was the equitoxic dose for induction of DNA single-strand
breaks by both gamma- and proton irradiation. However, protons were twice as effective as γ rays in induction of DNA double-strand
breaks. All breaks have been repaired for ≤10 h. Irradiation resulted in increased expression of p53 and ATM. Seven days after
irradiation, no signs of cell death and retinal degeneration were observed. Proton irradiation with 25 Gy resulted in destructive
changes in retina localized mainly in the photoreceptor layer. These changes were accompanied by enhanced expression of proapoptotic
proteins. A single systemic administration of MNU (70 mg/kg) increased intracellular levels of p53, PARP, FasR, and Caspase
3 followed by destructive changes in retina with sings of apoptosis in photoreceptors. Similarly to irradiation, a halved
MNU dose did not exhibit a cytotoxic effect on retina. A high level of spontaneous DNA damage at apurine and apyrimidine sites
were observed in mouse retina. The results show that there is a genotoxic threshold in initiation of retinal cell death in
vivo. It is suggested that topoisomerase 2 translates primary DNA damage into a cytotoxic effect in retina. 相似文献
10.
Changes in leukocyte counts and in the gut microflora of laboratory rats irradiated with a single whole-body dose of γ rays
(5.0 Gy) were determined. The number of leukocytes was lower especially 1 and 2 weeks after irradiation. A significant decrease
in lymphocytes was observed 1 week and in monocytes 1 and 2 weeks after irradiation. In parallel with these changes, an increase
in common microflora was observed; some microorganisms, which normally are not present in duodenum, liver and mouth cavity,
were detected in these organs. 相似文献
11.
An adaptive response induced by long-term low-dose-rate irradiation in mice was evaluated in terms of the amount of DNA damage in the spleen analyzed by a comet assay. C57BL/ 6N female mice were irradiated with 0.5 Gy of (137)Cs gamma rays at 1.2 mGy/h; thereafter, a challenge dose (0.4, 0.8 or 1.6 Gy) at a high dose rate was given. Less DNA damage was observed in the spleen cells of preirradiated mice than in those of mice that received the challenge dose only; an adaptive response in terms of DNA damage was induced by long-term low-dose-rate irradiation in mice. The gene expression of catalase and Mn-SOD was significantly increased in the spleen after 23 days of the low-dose-rate radiation (0.5 Gy). In addition, the enzymatic activity of catalase corresponded to the gene expression level; the increase in the activity was observed at day 23 (0.5 Gy). These results suggested that an enhancement of the antioxidative capacities played an important role in the reduction of initial DNA damage by low-dose-rate radiation. 相似文献
12.
Annique C. Dombrowsky Karin Burger Ann-Kristin Porth Marlon Stein Martin Dierolf Benedikt Gnther Klaus Achterhold Bernhard Gleich Annette Feuchtinger Stefan Bartzsch Elke Beyreuther Stephanie E. Combs Franz Pfeiffer Jan J. Wilkens Thomas E. Schmid 《Radiation and environmental biophysics》2020,59(1):111-120
Microbeam radiation therapy (MRT), a preclinical form of spatially fractionated radiotherapy, uses an array of microbeams of hard synchrotron X-ray radiation. Recently, compact synchrotron X-ray sources got more attention as they provide essential prerequisites for the translation of MRT into clinics while overcoming the limited access to synchrotron facilities. At the Munich compact light source (MuCLS), one of these novel compact X-ray facilities, a proof of principle experiment was conducted applying MRT to a xenograft tumor mouse model. First, subcutaneous tumors derived from the established squamous carcinoma cell line FaDu were irradiated at a conventional X-ray tube using broadbeam geometry to determine a suitable dose range for the tumor growth delay. For irradiations at the MuCLS, FaDu tumors were irradiated with broadbeam and microbeam irradiation at integral doses of either 3 Gy or 5 Gy and tumor growth delay was measured. Microbeams had a width of 50 µm and a center-to-center distance of 350 µm with peak doses of either 21 Gy or 35 Gy. A dose rate of up to 5 Gy/min was delivered to the tumor. Both doses and modalities delayed the tumor growth compared to a sham-irradiated tumor. The irradiated area and microbeam pattern were verified by staining of the DNA double-strand break marker γH2AX. This study demonstrates for the first time that MRT can be successfully performed in vivo at compact inverse Compton sources. 相似文献
13.
Effect of radiation on regeneration of Chinese narcissus and analysis of genetic variation with AFLP and RAPD markers 总被引:1,自引:0,他引:1
Gang Lu Xiaoying Zhang Yijing Zou Qingcheng Zou Xun Xiang Jiashu Cao 《Plant Cell, Tissue and Organ Culture》2007,88(3):319-327
The aim of our study was to establish an efficient in vitro propagation protocol for Chinese narcissus (Narcissus tazetta var. chinensis) to obtain variants of this species using γ-radiation treatment and evaluate the effectiveness of this system for variant
induction using amplification fragment length polymorphism (AFLP) and randomly amplified polymorphic DNA (RAPD) analysis.
Various doses (5–100 Gy) of gamma rays were applied to investigate the effect of radiation on adventitious bud formation from
bulb-scales and the survival rate of plantlets. It was demonstrated that the regeneration of Chinese narcissus was very sensitive
to gamma radiation even at low doses. The survival and multiplication rate significantly decreased with an increase of radiation
dose. The optimal irradiation dose for survival and mutation induction was approximately 10 Gy. The genetic variations among
the regenerants derived from irradiated explants were evaluated by DNA fingerprinting using RAPD and AFLP markers which detected
a variation frequency of 8.33% and 15.48% respectively. The high frequency of mutants detected by molecular markers indicated
that treatment of in vitro cultures with γ-rays may be an effective way to improve narcissus cultivars. 相似文献
14.
Irradiation stress adversely affects plant growth and development. The radio protective activity by glycinebetaine in plants
has not been reported, and its mechanism has not been known. Gamma rays at doses 0.0, 25, 50, 100, and 150 Gray (Gy) when
applied pre-sowingly to dry seeds of fenugreek from a cobalt source (60Co) with strength of 500 Ci and the dose rate of 0.54 Gy/min significantly reduced chlorophyll content, total protein, photosynthetic
efficiency (14CO2-fixation), total dry weight, the accumulation of reducing, non-reducing and total soluble sugars in comparison with un-irradiated
control. It also significantly repressed the activities of hydrolytic enzymes (α-amylase and invertase), the carboxylating
enzyme (ribulose-1,5-bisphosphate-carboxylase/oxygenase) in the developed fenugreek plants. Soaking irradiated seeds with
glycinebetaine (50 mM) for 24 h partially alleviated the depression effects of irradiation in these parameters. γ-irradiation
treatment increased significantly H2O2 content. Presoaking irradiated seeds with GB decreased significantly the H2O2 level. The magnitude of the reversal decreased with increasing the irradiation dose. γ-irradiation induced a significant
decrease in the level of nucleic acids (DNA and RNA) accompanied by a corresponding induction of hydrolytic activities of
DNase and RNase in the developed plants in comparison with un-irradiated control. Those changes were more significant at higher
γ-ray doses. Post-treatment of irradiated seeds with GB partially alleviated the adverse effects of radiation. It significantly
increased nucleic acid levels and repressed the activities of DNase and RNase. The protective role played by glycinebetaine
was more significant at lower γ-ray doses. Pretreatment of seeds with GB may play an effective role in the radio-repair mechanism. 相似文献
15.
Kyung-Wan Baek Da-In Lee Shin Ae Kang Hak Sun Yu 《Journal of physiology and biochemistry》2020,76(1):159-168
Animal studies have demonstrated that the ratio of M1 (M1Φ) to M2 (M2Φ) macrophage-specific gene expression in adipose tissue (AT) may be altered by chronic exercise; however, whether macrophage polarization is induced under these conditions has not yet been reported. Therefore, this study aimed to investigate the effect of chronic exercise on M1Φ/M2Φ polarization in the AT of high-fat diet (HFD)-induced obese mice. Exercise-induced differences in M1Φ/M2Φ polarization were verified via an exercise intensity study (EIS) in which different levels of exercise intensity were evaluated. Obesity was induced in male C57BL/6 J mice by feeding them with an HFD for 6 weeks. The study consisted of four groups: control group (CON), HFD-fed group (HFD), HFD-fed with exercise group (HFD + EXE), dietary conversion from HFD to normal diet (ND) group (DC), and dietary conversion from HFD to ND group (DC + EXE). For EIS, the HFD + EXE group was divided into three subgroups: low- (LI), mid- (MI), and high- (HI) intensity exercise. The total intervention period was 8 weeks. M1Φ/M2Φ polarization was confirmed by flow cytometry. M2Φ polarization in the AT of obese mice was significantly higher in HFD + EXE mice than in HFD mice, despite the HFD intake. In the EIS, M2Φ polarization was most pronounced in HFD + EXE-HI mice than in HFD mice. It can be proposed that the enhanced insulin resistance and inflammation by obesity can be improved by the increase of M2Φ polarization which is achieved by relatively high-intensity exercise. 相似文献
16.
We present an analysis of X-ray-induced damage in ΦX174 plasmid DNA, applying doses between D = 250 and 1,500 Gy. To analyse this damage in detail, the distribution of plasmid fragments after irradiation have been determined
by scanning force microscopy. The results show that even for the lowest dose of D = 250 Gy, a significant amount of double-strand breaks are observed. For increasing dose, the percentage of small fragments
increases and is accompanied by a shortening of the average fragment length from < L> = 1,400 nm for a dose of D = 250 Gy to < L> = 1,080 nm after irradiation with D = 1,500 Gy. The most crucial parameter, the average number of double-strand breaks per broken plasmid (<DSBb> ) has been determined for the first time for the applied doses. The results show that the average number of DSBs per broken
plasmid <DSBb> increases almost linearly from a value of <DSBb> = 1.3 after irradiation with D = 250 Gy to <DSBb> = 1.7 after exposure to D = 1,500 Gy. The presented results show that the amount of DSBs induced by X-ray radiation in plasmid DNA can be calculated
with high accuracy by means of scanning force microscopy, providing relevant information regarding the interaction of X-rays
with DNA molecules.
相似文献
M. BrezeanuEmail: |
17.
Aqueous extract of Podophyllum hexandrum (RP-1), which has been reported to render more than 82% survival against whole body lethal (10 Gy) gamma-irradiation in mice,
was further investigated for its immunomodulatory potential. In this study, no significant change could be scored in peritoneal
macrophages survival up to 8th day after whole body irradiation. RP-1 treatment (200 mg/kg body weight, i.p.) alone or 2 h
before whole body irradiation enhanced macrophage survival significantly (p < 0.05) as compared to irradiated control mice. In irradiated animals, there was significant (p < 0.01) reduction in splenocyte survival and proliferation as revealed by 3H-TdR method. RP-1 treatment (200 mg/kg) alone
or 2 h before irradiation countered the decrease in survival of splenocytes and proliferation significantly (p < 0.05) as compared to irradiated control group. Whole body irradiation also significantly (p < 0.05) reduced the population of CD4+ and CD8+ T cells and bone marrow GM-CFU at 24 h and 72 h post-irradiation intervals,
respectively, as compared to unirradiated control. RP-1 treatment 2 h before whole body irradiation countered the decrease
in CD4+ and CD8+ T cells populations and CGM-CFU. Nitric oxide free radicals generation was enhanced significantly (p < 0.05) in the supernatant of peritoneal macrophage cultures exposed to 2 Gy gamma radiation ex vivo in comparison to unirradiated control, which was reduced by pre-irradiation (−2 h) administration of RP-1. Whole body irradiation
(10 Gy) also reduced the serum titres of IL-3, IL-1 and various IgG isotypes observed at different post-irradiation time interval.
RP-1 treatment alone or before whole body irradiation countered radiation induced decrease in the titre of IL-1, IL-3 and
IgG’s in the serum of mice. These findings indicate immunostimulatory potential of RP-1. 相似文献
18.
The effect of ferulic acid was studied on γ-radiation-induced relaxation of plasmid pBR322 DNA and induction of DNA strand
breaks in peripheral blood leukocytes and bone marrow cells of mice exposed to whole body γ-radiation. Presence of 0.5 mM
ferulic acid significantly inhibited the disappearance of supercoiled (ccc) plasmid pBR322 with a dose modifying factor (DMF)
of 2.0. Intraperitoneal administration of different amounts (50, 75 and 100 mg/kg body weight) of ferulic acid 1 h prior to
4 Gy γ-radiation exposure showed dose-dependent decrease in the yield of DNA strands breaks in murine peripheral blood leukocytes
and bone marrow cells as evidenced from comet assay. The dose-dependent protection was more pronounced in bone marrow cells
than in the blood leukocytes. It was observed that there was a time-dependent disappearance of radiation induced strand breaks
in blood leukocytes (as evidenced from comet parameters) following whole body radiation exposure commensuration with DNA repair.
Administration of 50 mg/kg body weight of ferulic acid after whole body irradiation of mice resulted disappearance of DNA
strand breaks at a faster rate compared to irradiated controls, suggesting enhanced DNA repair in ferulic acid treated animals.
(Mol Cell Biochem xxx: 209–217, 2005) 相似文献
19.
The biological effectiveness of neutrons from the neutron therapy facility MEDAPP (mean neutron energy 1.9 MeV) at the new
research reactor FRM II at Garching, Germany, has been analyzed, at different depths in a polyethylene phantom. Whole blood
samples were exposed to the MEDAPP beam in special irradiation chambers to total doses of 0.14–3.52 Gy at 2-cm depth, and
0.18–3.04 Gy at 6-cm depth of the phantom. The neutron and γ-ray absorbed dose rates were measured to be 0.55 Gy min−1 and 0.27 Gy min−1 at 2-cm depth, while they were 0.28 and 0.25 Gy min−1 at 6-cm depth. Although the irradiation conditions at the MEDAPP beam and the RENT beam of the former FRM I research reactor
were not identical, neutrons from both facilities gave a similar linear-quadratic dose–response relationship for dicentric
chromosomes at a depth of 2 cm. Different dose–response curves for dicentrics were obtained for the MEDAPP beam at 2 and 6 cm
depth, suggesting a significantly lower biological effectiveness of the radiation with increasing depth. No obvious differences
in the dose–response curves for dicentric chromosomes estimated under interactive or additive prediction between neutrons
or γ-rays and the experimentally obtained dose–response curves could be determined. Relative to 60Co γ-rays, the values for the relative biological effectiveness at the MEDAPP beam decrease from 5.9 at 0.14 Gy to 1.6 at
3.52 Gy at 2-cm depth, and from 4.1 at 0.18 Gy to 1.5 at 3.04 Gy at 6-cm depth. Using the best possible conditions of consistency,
i.e., using blood samples from the same donor and the same measurement techniques for about two decades, avoiding the inter-individual
variations in sensitivity or the differences in methodology usually associated with inter-laboratory comparisons, a linear-quadratic
dose–response relationship for the mixed neutron and γ-ray MEDAPP field as well as for its fission neutron part was obtained.
Therefore, the debate on whether the fission-neutron induced yield of dicentric chromosomes increases linearly with dose remains
open. 相似文献
20.
D. Bhattacharjee R. Rajan L. Krishnamoorthy B. B. Singh 《Radiation and environmental biophysics》1997,36(2):125-128
Mouse spermatogonial germ cells are highly sensitive to ionizing radiation. Lithium salts are reported to stimulate the postirradiation
recovery of hematopoietic marrow cells. We have, therefore, examined whether administered lithium chloride (LiCl) would also
be able to protect the mouse germinal cells against radiation injury. Taking DNA synthesis as an endpoint, our results show
that the testicular DNA-specific activity in irradiated mice was higher by 61% on average when they had been pretreated with
LiCl both 24 h and 1 h prior to γ-irradiation (2.0 Gy). It was also observed that the DNA synthetic activity in the germinal cells fully recovered after LiCl
pretreatment at doses of 40 mg per kg body weight prior to total body irradiation of 0.05–0.25 Gy, whereas at doses of 0.5–6.0
Gy, following the same procedure of LiCl pretreatment, only an incomplete recovery was observed. The dose reduction factor
for LiCl is 1.84. The current findings indicate that pretreatment with LiCl provides considerable protection against radiation
damage in mouse spermatogonia.
Received: 18 October 1996 / Accepted in revised form: 3 April 1997 相似文献