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ABSTRACT: Adult male ICR mice were pre-exposed to non-ionizing radiofrequency fields (RF), 900MHz at 120μW/cm(2) power density for 4hours/day for 7 days (adaptation dose, AD) and then subjected to an acute whole body dose of 3Gy γ-radiation (challenge dose, CD). The classical micronucleus (MN) assay was used to determine the extent of genotoxicity in immature erythrocytes in peripheral blood and bone marrow. The data obtained in mice exposed to AD+CD were compared with those exposed to CD alone. The results indicated that in both tissues, the MN indices were similar in un-exposed controls and those exposed to AD alone while a significantly increased MN frequency was observed in mice exposed to CD alone. Exposure of mice to AD+CD resulted in a significant decrease in MN indices compared to those exposed to CD alone. Thus, the data suggested that pre-exposure of mice to non-ionizing RF is capable of 'protecting' the erythrocytes in the blood and bone marrow from genotoxic effects of subsequent γ-radiation. Such protective phenomenon is generally described as 'adaptive response' (AR) and is well documented in human and animal cells which were pre-exposed to very low doses of ionizing radiation. It is interesting to observe AR being induced by non-ionizing RF.
Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis 01/2013; · 2.85 Impact Factor
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ABSTRACT: Radon and its progeny are confirmed to be type I carcinogenic agents accounting for increased risks in 10% of observed lung cancers globally. However, the underlying carcinogenic mechanisms are largely unknown. In the present study, BEAS2B cells were directly exposed twice to 20,000 Bq/m(3) radon gas for 20 min once (first passage) and subsequently 10 times (fifth passage). The fifth-passage cells were then subcultured for 1 and 20 generations (named Rn5-1 and Rn5-20, respectively). Molecular mechanisms indicative of malignant transformation were assessed by determination of apoptosis, seroresistance, and microRNA (miRNA) expression profiles. The microRNA profiles were used to assess the functional annotations of the target genes. Data indicated an increased seroresistance and colony efficiency on soft agar, and enhanced apoptosis resistance in the Rn5-20 cells with significant differential expressions in some miRNA, including hsa-miR-483-3p, hsa-miR-494, hsa-miR-2115*, hsa-miR-33b, hsa-miR-1246, hsa-miR-3202, hsa-miR-18a, hsa-miR-125b, hsa-miR-17*, and hsa-miR-886-3p. Functional annotation demonstrated that these miRNA target genes were predominantly involved in the regulation of cell proliferation, differentiation, and adhesion during the process of malignant transformation, which is associated with signal pathways such as mitogen-activated protein kinase (MAPK), Int and Wg (Wnt), reactive oxygen species (ROS), nuclear factor κB (NF-κB), and other genes regulating cell cycles.
Journal of Toxicology and Environmental Health Part A 01/2013; 76(2):107-19. · 1.83 Impact Factor
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ABSTRACT: To study the chronotoxicity and mechanism of fenvalerate (Fen) on the male reproductive system.
Forty-nine healthy clean SD rats in a 12h: 12h light-dark photoperiod, which were divided into seven groups: control group and six Fen groups (Fen 2, Fen 6, Fen 10, Fen 14, Fen 18, Fen 22). Fen groups were administered by intra-gastric injection of Fen (12 mg/kg BW) respectively at corresponding zeitgeber time (ZT 02, ZT 06, ZT 10, ZT 14, ZT 18, ZT 22) for 30 days. The control group rats were administered with equal volume of edible blend oil. One side testicular was used to make HE paraffin slice. Germ cell (Daily sperm production, DSP. Sperm live rate, SLR. Abnormal sperm rate, ASR), the activities testicular mark enzymes and the levels of Sex hormones (testosterone, T, estradiol, E2) in testicular were measured.
Compared with the control group, Fen cause the pathological changes of testicular tissue in rats, and the most serious injuries occurred in ZT 18. DSP, SLR, ACP and T in testicular were decreased, ASR and E2 were increased. Results from Cosinor analysis showed that Circadian rhythms of the changes compared to the control group in DSP, SLR and ACP were validated, and sensitive point in time to Fen was respectively at ZT 04, ZT 14, ZT 23.
The results suggested that the effects of Fen on male reproductive function were time-dependent in a circadian day.
Wei sheng yan jiu = Journal of hygiene research 11/2012; 41(6):905-10.
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ABSTRACT: Radon and radon progeny inhalation exposure are recognized to induce lung cancer. To explore the role of mitochondria in radon-induced carcinogenesis in humans, an in vitro partially depleted mitochondrial DNA (mtDNA) cell line (ρ-) was generated by treatment of human bronchial epithelial (HBE) cells (ρ+) with ethidium bromide (EB). The characterization of ρ- cells indicated the presence of dysfunctional mitochondria and might thus serve a reliable model to investigate the role of mitochondria. In a gas inhalation chamber, ρ- and ρ+ cells were exposed to radon gas produced by a radium source. Results showed that apoptosis was significantly increased both in ρ- and ρ+ cells irradiated by radon. Moreover, apoptosis in ρ- cells showed a lower level than in ρ+ cells. Radon was further found to depress mitochondrial membrane potential (MMP) of HBE cells with knockdown mtDNA. Production of reactive oxygen species (ROS) was markedly elevated both in ρ- and ρ+ cells exposed to radon. The distribution of phases of cell cycle was different in ρ- compared to ρ+ cells. Radon irradiation induced a rise in G2/M and decrease in S phase in ρ+ cells. In ρ- cells, G1, G2/M, and S populations remained similar to cells exposed to radon. In conclusion, radon-induced changes in ROS generation, MMP and cell cycle are all attributed to reduction of apoptosis, which may trigger and promote cell transformation, leading to carcinogenesis. Our study indicates that the use of the ρ- knockdown mtDNA HBE cells may serve as a reliable model to study the role played by mitochondria in carcinogenic diseases.
Journal of Toxicology and Environmental Health Part A 09/2012; 75(18):1111-9. · 1.83 Impact Factor
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ABSTRACT: Radiofrequency fields (RF) at 1800 MHz are known to affect melatonin (MEL) and testosterone in male rats, but it remains to be determined whether RF affected circadian rhythm of these plasma hormones. Male Sprague-Dawley rats were exposed to 1800-MHz RF at 208 μw/cm² power density (SAR: 0.5762 W/kg) at different zeitgeber (ZT) periods of the day, including 0 (ZT0), 4 (ZT4), 8 (ZT8), 12 (ZT12), 16 (ZT16), and 20 (ZT20) h. RF exposure was 2 h/d for 32 d. From each rat, the concentrations of plasma MEL and testosterone were determined in plasma after RF exposure and compared with controls. The results confirmed the existence of circadian rhythms in the synthesis of MEL and testosterone, but revealed an inverse relationship in peak phase of these rhythms. These rhythms were disturbed after exposure to RF, with the effect being more pronounced on MEL than testosterone. The most pronounced effect of RF exposure on MEL and testosterone appears to be in rats exposed to RF at ZT 16 and ZT0 h, respectively. Data suggest that regulation of testosterone is controlled by MEL and that MEL is more sensitive to RF exposure.
Journal of Toxicology and Environmental Health Part A 09/2012; 75(18):1120-8. · 1.83 Impact Factor
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ABSTRACT: Despite the fact that animal and human epidemiological studies confirmed a link between radon exposure in homes and increased risk of lung cancer in general population, other types of cancers induced by radon, such as leukemia, have not been consistently demonstrated. The aim of this review was to summarize data published thus far from ecological and case-control studies in exposed populations, taking into account radon dose estimation and evidence of radon-induced genotoxicity, in an effort to clarify the correlation between home radon exposure and incidence of childhood leukemia. Among 12 ecological studies, 11 reported a positive association between radon levels and elevated frequency of childhood leukemia, with 8 being significant. In conjunction with ecological studies, several case-control studies on indoor radon exposure and childhood leukemia were examined, and most investigations indicated a weak association with only a few showing significance. A major source of uncertainty in radon risk assessment is radon dose estimate. Methods for radon exposure measurement in homes of children are one of the factors that affect the risk estimates in a case-control study. The effects of radon-induced genetic damage were studied both in vitro and in vivo using genetic endpoints including chromosomal aberration (CA), micronuclei (MN) formation, gene mutation, and deletions and insertions. By applying a meta-analysis, an increased risk of childhood leukemia induced by indoor radon exposure was noted for overall leukemia and for acute lymphoblastic leukemia (ALL). Data thus indicated an association between environmental radon exposure and elevated leukemia incidence, but more evidence is required in both human investigations and animal mechanistic research before this assumption may be confirmed with certainty.
Journal of Toxicology and Environmental Health Part B 07/2012; 15(5):332-47. · 4.72 Impact Factor
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ABSTRACT: Oxidative damage can be induced by many environmental stressors. 8-Hydroxydeoxyguanosine (8-OHdG) has been used as a biomarker of oxidative DNA damage in both in vitro and in vivo studies. In the present study, Wistar rats were exposed to radon gas at a concentration of 100,000Bq/m(3) for 12 h/d for 30, 60, and 120 d, equivalent to cumulative doses of 60, 120, and 240 working level months (WLM), respectively. Changes in levels of 8-OHdG, reactive oxygen species (ROS), and total antioxidant (T-AOC), as well as expressions of some DNA repair enzymes such as 8-oxoguanine DNA glycosylase (OGG1) and MutT homolog 1 (oxidized purine nucleoside triphosphatase, MTH1), were determined in rat urine, peripheral blood lymphocytes, and lung after exposure to radon. The results revealed an increase in 8-OHdG and ROS levels, a decrease in T-AOC levels, and reduced OGG1 and MTH1 expression levels. The elevated amount of 8-OHdG in urine or lymphocytes was positively correlated with the cumulative exposure dose, whereas OGG1 and MHT1 expression levels in lung were inversely correlated with cumulative exposure dose. These findings indicate that oxidative damage induced by radon may be involved in radon-induced carcinogenesis.
Journal of Toxicology and Environmental Health Part A 06/2012; 75(12):694-9. · 1.83 Impact Factor
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ABSTRACT: The lack of apoptotic pathways may lead to undesirable cell survival and proliferation, which are recognized hallmarks of cancer. It is well known that exposure to cigarette smoke induces DNA lesions in pulmonary cells. At present, it is not fully elucidated whether these lesions are repaired to restore normal functions or induce apoptosis. In order to examine the role of apoptosis in smoking-induced effects, immortalized human bronchial epithelial cells (BEAS-2B) were exposed to cigarette smoke and examined for parameters associated with apoptosis and neoplastic transformation. Our results indicated a significant reduction in apoptosis and enhanced neoplastic transformation and decreased mitochondrial membrane potential Δψm of mitochondria compared to control cells. Time-course experiments revealed increased aberrant methylation of CpG islands of RAS-associated domain family protein 1A (RASSF1A) and O (6)-methylguanine-DNA-methyltransferase (MGMT). The activities were downregulated and repair of DNA adducts was inhibited. Our observations suggested that although cigarette smoke-induced damage in BEAS-2B cells after chronic exposure is not necessarily lethal, as evidenced by cell viability, the protein expression levels of caspase-3 showed a decrease in the S20 passage (metaphase) but subsequently increased from S30 to S40 (anaphase). Survivin expression was significantly changed in S5 cells, and this rise was maintained until S40. Our data suggest that the potency of cigarettes as carcinogens may be due to their ability to induce aberrant gene expression and failure to trigger apoptosis leads to subsequent neoplastic transformation.
Journal of Toxicology and Environmental Health Part A 06/2012; 75(12):707-20. · 1.83 Impact Factor
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ABSTRACT: The aim of this study was to characterize genomic instability induced by ionizing radiation (IR) in human hepatocytes as reflected by alterations in cloning efficiency, micronucleus (MN) frequency, and apoptosis. The human normal liver 7702 cell line (HL7702) was subjected to initial irradiation of (60)Co-γ ray at doses of 0 (control group), 2, 4, 6, 8, or 10 Gy in each group. Progeny of surviving cells from a second irradiation at dose of 2 Gy were cultured for 15 passages until they were transferred. The cloning efficiency, MN frequency, and apoptotic rate were measured after the initial irradiation, and repeated at passage 15 before and after the second irradiation. The initial irradiation resulted in a dose-dependent decline in cloning efficiency and an increase in MN frequency and apoptotic rate. At passage 15 in progeny of initially irradiated cells, cloning efficiency, MN frequency returned to control levels while apoptotic rate rose. After the second irradiation, cloning efficiency fell while a rise in MN frequency and apoptosis occurred. Our results show that the second irradiation may further enhance cell progeny injury induced by initial irradiation, such that genomic instability that may be difficult to detect after one irradiation is more apparent with subsequent irradiation.
Journal of Toxicology and Environmental Health Part A 06/2012; 75(12):700-6. · 1.83 Impact Factor
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ABSTRACT: Numbers of epidemiological studies assessing residential radon exposure and risk of lung cancer have yielded inconsistent results.
We therefore performed a meta-analysis of relevant published case- control studies searched in the PubMed database through July 2011 to examine the association. The combined odds ratio (OR) were calculated using fixed- or random-effects models. Subgroup and dose-response analyses were also performed.
We identified 22 case-control studies of residential radon and lung cancer risk involving 13,380 cases and 21,102 controls. The combined OR of lung cancer for the highest with the lowest exposure was 1.29 (95% CI 1.10-1.51). Dose-response analysis showed that every 100 Bq/m3 increment in residential radon exposure was associated with a significant 7% increase in lung cancer risk. Subgroup analysis displayed a more pronounced association in the studies conducted in Europe. Studies restricted to female or non-smokers demonstrated weakened associations between exposure and lung cancer.
This meta- analysis provides new evidence supporting the conclusion that residential exposure to radon can significantly increase the risk of lung cancer in a dose-response manner.
Asian Pacific journal of cancer prevention: APJCP 01/2012; 13(6):2459-65. · 0.66 Impact Factor
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ABSTRACT: The phenomenon of adaptive response (AR) in animal and human cells exposed to ionizing radiation is well documented in scientific literature. We have examined whether such AR could be induced in mice exposed to non-ionizing radiofrequency fields (RF) used for wireless communications. Mice were pre-exposed to 900 MHz RF at 120 µW/cm(2) power density for 4 hours/day for 1, 3, 5, 7 and 14 days and then subjected to an acute dose of 3 Gy γ-radiation. The primary DNA damage in the form of alkali labile base damage and single strand breaks in the DNA of peripheral blood leukocytes was determined using the alkaline comet assay. The results indicated that the extent of damage in mice which were pre-exposed to RF for 1 day and then subjected to γ-radiation was similar and not significantly different from those exposed to γ-radiation alone. However, mice which were pre-exposed to RF for 3, 5, 7 and 14 days showed progressively decreased damage and was significantly different from those exposed to γ-radiation alone. Thus, the data indicated that RF pre-exposure is capable of inducing AR and suggested that the pre-exposure for more than 4 hours for 1 day is necessary to elicit such AR.
PLoS ONE 01/2012; 7(2):e32040. · 4.09 Impact Factor
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ABSTRACT: Human promyelocytic leukemia HL-60 cells were pre-exposed to non-ionizing 900 MHz radiofrequency fields (RF) at 12 µW/cm(2) power density for 1 hour/day for 3 days and then treated with a chemotherapeutic drug, doxorubicin (DOX, 0.125 mg/L). Several end-points related to toxicity, viz., viability, apoptosis, mitochondrial membrane potential (MMP), intracellular free calcium (Ca(2+)) and Ca(2+)-Mg(2+) -ATPase activity were measured. The results obtained in un-exposed and sham-exposed control cells were compared with those exposed to RF alone, DOX alone and RF+DOX. The results indicated no significant differences between un-exposed, sham-exposed control cells and those exposed to RF alone while treatment with DOX alone showed a significant decrease in viability, increased apoptosis, decreased MMP, increased Ca(2+) and decreased Ca(2+)-Mg(2+-)ATPase activity. When the latter results were compared with cells exposed RF+DOX, the data showed increased cell proliferation, decreased apoptosis, increased MMP, decreased Ca(2+) and increased Ca(2+)-Mg(2+)-ATPase activity. Thus, RF pre-exposure appear to protect the HL-60 cells from the toxic effects of subsequent treatment with DOX. These observations were similar to our earlier data which suggested that pre-exposure of mice to 900 MHz RF at 120 µW/cm(2) power density for 1 hours/day for 14 days had a protective effect in hematopoietic tissue damage induced by subsequent gamma-irradiation.
PLoS ONE 01/2012; 7(9):e46102. · 4.09 Impact Factor
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ABSTRACT: To study the effect and mechanism of Soybean Isoflavones (SIF) on the cognitive performance of female mice after sleep deprivation for 72h.
Forty female mice were randomly divided into 5 groups:the control, sleep deprivation control (SDC), and three SIF groups (SIF L, SIF M and SIF H). SIF groups were administered by intra-gastric injection of SIF 20, 40 and 80 mg/kg bw respectively for 30 days. The control and SDC groups were administered with equal volume of normal saline. The 72h SD mice model was induced by the single platform technique. The cognitive ability of mice was tested by Y-maze. Antioxidant indicators (CAT, MDA and T-AOC) and neurotransmitters (NO, Glu and Ach) in cerebra were measured.
Compared with the control group, the cognitive abilities, CAT activities, T-AOC and Ach levels were decreased and NO, MDA and GLu contents were increased in mice after sleep deprivation for 72h. Compared with the SDC group, the cognitive abilities were improved and Ach contents were increased in SIF M and SIF H groups, T-AOC levels were improved in three SIF groups. CAT activities, MDA, NO and Glu contents were decreased in SIF H group only.
The cognitive ability of 72h SD female mice could be improved by SIF, the mechanism of which might be involved in increasing antioxidant function, decreasing the damage of free radicals on cranial nerves and adjusting the neuron transmitter of cerebra.
Wei sheng yan jiu = Journal of hygiene research 07/2011; 40(4):499-502.
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ABSTRACT: To investigate whether impaired osteogenesis resulting from vitamin D deficiency can influence hematopoiesis recovery after radiation, the 25-hydroxyvitamin D-1α-hydroxylase (1α-hydroxylase) gene knockout (KO) mice and wild type (WT) mice were subjected to different doses of gamma ray. The survival rates, peripheral blood cell counts and bone marrow cellularity were studied after irradiation (IR). The survival rates of the KO mice were significantly lower than that of WT mice after 6 or 8 Gy dose of radiation. The recovery of white blood cells in KO mice was significantly delayed compared with that in WT mice after radiation. The red blood cell number in WT mice was observed to increase more than that in KO mice at days 14 and 28 after radiation. The nadir platelet count in KO mice was nearly half of that in WT mice. Dramatically higher bone marrow cell numbers were found in WT mice compared with KO mice. Our findings demonstrate the enhanced radiosensitivity in 1,25-dihydroxyvitamin D3 (1,25-(OH)(2)D(3)) deficient mice.
Journal of Radiation Research 02/2011; 52(2):215-9. · 1.68 Impact Factor
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ABSTRACT: To investigate whether an adaptive response can be induced in mice which were pre-exposed to 900 MHz radiofrequency fields.
Adult male Kunming mice were exposed to 900 MHz radiofrequency fields (RF) at power intensities of 12, 120 and 1200 μW/cm(2) for 1 h/day for 14 days and then subjected to whole body gamma-irradiation. The results were compared with those in unexposed control animals and those exposed to gamma-irradiation alone (without pre-exposure to RF). The extent of survival and hematopoietic tissue damage (assessed in the form of nucleated colony forming cells in the bone marrow and colony forming cells in the spleen of lethally irradiated 'recipient' mice) as well as the expression of cell cycle-related genes were investigated.
The results indicated a significant increase in survival time, reduction in the hematopoietic tissue damage in RF pre-exposed mice which were gamma-irradiated (as compared with those exposed to gamma-radiation alone). This was accompanied by significantly increased expression of cell cycle-related genes, namely, cyclin-D1, cyclin-E, cyclin-DK4 and cyclin-DK2 in hematopoietic cells.
Pre-exposure of mice to 900 MHz radiofrequency fields has resulted in a significant reduction in hematopoietic damage caused by subsequent exposure to ionising radiation. This phenomenon appears to be similar to that of the 'adaptive response' which is well documented in scientific literature.
International Journal of Radiation Biology 02/2011; 87(7):720-8. · 2.28 Impact Factor
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ABSTRACT: To investigate whether 25-hydroxyvitamin D [25(OH)D] can mediate effects without being converted to 1α,25-dihydroxyvitamin D [1,25(OH)2D].
Vitamin D3 (VD3) was injected intramuscularly to 25-hydroxyvitamin D-1α-hydroxylase [1α(OH)ase] gene knockout (KO) male mice with a dose of 10,000 IU per week for 4 weeks. Skeleton Parameters and Serum biochemistry in mice were assayed.
Serum 25(OH)D3 levels increased from 41 to 212 ng/mL in KO mice injected with VD3. Our results show that VD3 injections significantly increased the body weight of KO mice and there were no significant differences in body weight at 7 weeks of age between VD3-treated KO mice and wildtype (WT) mice. After 1 month injection, serum calcium and phosphorus levels of the KO mice were found indistinguishable from those of their WT littermates. Serum parathyroid hormone level declined significantly, but remained higher in treated KO mice. The dry weight, percentage ash weight, and calcium content of femur were returned to normal levels in VD3-treated KO mice whereas the femoral length, although increased significantly, remained significantly smaller than that of WT mice. VD3 injections also normalized the growth plate of KO mice within normal width.
Our results demonstrate that high-dose VD3 injections can partially rescue the phenotype in 1α-hydroxylase gene KO mice. 25-Hydroxyvitamin D can mediate effects in the absence of conversion to 1α,25-dihydroxyvitamin D was confirmed in this study.
Endocrine Research 02/2011; 36(3):101-8. · 0.97 Impact Factor
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ABSTRACT: To study the adaptive response mechanisms in high background radiation area (HBRA) among Yangjiang local people through gene and protein expression of receptor for advanced glycation end products (RAGE) and S100A6 in peripheral blood and sputum in inhabitants of HBRA.
A total of 53 male inhabitants were selected from HBRA in Yangjiang as the exposure group, while 53 male inhabitants were selected from Enping (control area, CA)as the control group. The content of RAGE and S100A6 gene and protein were detected by RT-PCR and Western blotting assay. Thermo luminescent dosemeter(TLD) assay was used to measure the outside dose and estimate the effective dose.
The effective dose in CA and HBRA was respectively 1.95 mSv and 6.24 mSv, which was 3 fold difference. Compared with CA, RAGE and S100A6 expression were significantly reduced in both gene and protein level in HBRA. The relative median mRNA expression of RAGE and S100A6 in peripheral blood were respectively 0.28, 1.06 and 0.16, 0.79 in CA and HBRA group, there was significance (with analysis Z values of -2.587 and -2.328 respectively, P < 0.05) with Wilcoxon rank test. For the protein of sputum, the relative median expression were respectively 2.98, 2.25 and 0.53, 0.47 with significant difference (with analysis Z values of -2.201 and -2.366 respectively, P < 0.05) by Wilcoxon rank test.
The low expression of RAGE and S100A6 in HBRA group might be correlated with the adaptive response and the low mortality of cancer in HBRA.
Zhonghua yu fang yi xue za zhi [Chinese journal of preventive medicine] 09/2010; 44(9):815-9.
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ABSTRACT: This study was designed to construct and identify the subtracted cDNA library in peripheral blood cells of BALB/c mice and tracheal-bronchial epithelial cells of Wistar rats following exposure to radon inhalation. Two groups of the animals were exposed in a radon chamber at an accumulative dose of 100 WLM, while control animals were housed in a room at a background dose of 1 WLM. To construct a subtracted cDNA library enriched with differentially expressed genes, the SMART technique and suppression subtractive hybridization (SSH) assay were performed. The obtained forward and reverse cDNA fragments were directly inserted into a pMD-18 vector and transformed into Escherichia coli JM109. In total, 593 white bacterial clones were selected from both forward- and reverse-subtracted libraries. Among them, 81 clones were chosen for their differential expressions based on reverse Northern blot. Portions of these cDNA clones were also verified by a quantitative real-time polymerase chain reaction (PCR). The screening resulted in 14 upregulative and 8 downregulative known function/annotation genes, which were revealed to be functionally related to cell proliferation, cell oxidative and DNA damage, apoptosis, and tumor promotion. Access numbers were obtained from the GenBank for 11 unknown expressed sequence tags (EST). Analysis of biological roles of these cDNA fragments may provide further insight into mechanisms underlying adverse molecular events induced by high-dose radon exposure.
Journal of Toxicology and Environmental Health Part A 01/2010; 73(7):499-506. · 1.83 Impact Factor
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ABSTRACT: The effects of in vitro irradiation on proliferation and hematopoietic supportive functions of stromal cells were studied. To assess the effects of radiation on stromal cells proliferation, marrow cells were exposed to a single dose of gamma radiation. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay showed that stromal cell proliferation was significantly suppressed after radiation in a dose-dependent manner. Stromal layers obtained from irradiated marrow cells failed to establish adherent layers after 6, 8, or 10 Gy of radiation. To assess the functions of stromal cells that survived radiation, stromal layers derived from irradiated marrow cells were cocultured with freshly isolated autologous hematopoietic cells and assayed for their capacity to support prolonged granulocyte-macrophage progenitors (CFU-GM) production. Stromal layers derived from 2-Gy-irradiated marrow cells resulted in similar CFU-GM production as control cells, while stromal layers derived from 4- to 10-Gy-irradiated marrow cells significantly decreased CFU-GM production. To study the influence of radiation on hematopoietic supportive capacity in established stromal layers, stromal layers generated from non-irradiated marrow cells were irradiated and cocultured with freshly isolated autologous hematopoietic cells. Established stromal layers irradiated up to 10 Gy sustained prolonged CFU-GM production, suggesting that hematopoietic stromal supportive functions remained intact at this dose of radiation. In conclusion, our results indicated that proliferation of stromal cells and bone-marrow stromal layer formation from stromal cells are sensitive to radiation in vitro, while established bone-marrow stromal layer originating from stromal cells is relatively resistant to radiation. Data generated may have implications in future bone-marrow transplantation research.
Journal of Toxicology and Environmental Health Part A 01/2010; 73(7):514-9. · 1.83 Impact Factor
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ABSTRACT: This study was designed to characterize the differential protein expression in the progeny of human liver cells surviving exposure to ionizing radiation. The progeny of irradiated cells were derived from a human liver cell line exposed to 0, 2, 4, or 6 Gy of (60)Co gamma-irradiation. Total protein of the cells was extracted by two-dimensional electrophoresis (2-DE) and analyzed with ImageMaster 2D Platinum software. In total, 42 differentially expressed proteins from the progeny of irradiated cells were screened, of which 17 were identified by matrix assistant laser desorption ion-top flight-mass spectrometry (MALDI-TOF-MS) analysis. There were 4 upregulated and 13 downregulated proteins detected. The upregulated expression of two proteins, mitochondrial heat-shock 60-kD protein (HSP60) and globin transcription factor 1 (GATA-1), was further confirmed by immunoblotting. Database search revealed that these differentially expressed proteins may function in cell cycle regulation, cytoskeleton maintenance, stress response, and tumor metastasis, indicating an effect of radiation-induced genomic instability (RIGI) in the progeny of irradiated cells. Analysis on functional roles of the screened proteins may provide insight into further mechanistic investigations underlying molecular events induced by RIGI.
Journal of Toxicology and Environmental Health Part A 01/2010; 73(7):520-8. · 1.83 Impact Factor
