• Journal of Radiation Protection and Research
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• v.40 no.1
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• pp.25-35
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• 2015

We analyzed the differential effects of histopathology, apoptosis and expression of radiation response genes after chronic low dose rate (LDR) and acute high dose rate (HDR) radiation exposure in spleen, lung and liver of rats. Female 6-week-old Sprague-Dawley rats were used. For chronic low-dose whole body irradiation, rats were maintained for 14 days in a $^{60}Co$ gamma ray irradiated room and received a cumulative dose of 2 Gy or 5 Gy. Rats in the acute whole body exposure group were exposed to an equal dose of radiation delivered as a single pulse ($^{137}Cs$-gamma). At 24 hours after exposure, spleen, lung and liver tissues were extracted for histopathologic examination, western blotting and RT-PCR analysis. 1. The spleen showed the most dramatic differential response to acute and chronic exposure, with the induction of substantial tissue damage by HDR but not by LDR radiation. Effects of LDR radiation on the lung were only apparent at the higher dose (5 Gy), but not at lower dose (2 Gy). In the liver, HDR and LDR exposure induced a similar damage response at both doses. RT-PCR analysis identified cyclin G1 as a LDR-responsive gene in the spleen of rats exposed to 2 Gy and 5 Gy gamma radiation and in the lung of animals irradiated with 5 Gy. 2. The effects of LDR radiation differed among lung, liver, and spleen tissues. The spleen showed the greatest differential effect between HDR and LDR. The response to LDR radiation may involve expression of cyclin G1.

• Journal of Preventive Medicine and Public Health
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• v.33 no.2
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• pp.165-173
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• 2000

Objectives : To assess the availability of the glycophorin A (GPA) assay to detect the biological effect of ionizing radiation in workers exposed to low-doses of radiation. Methods : Information on confounding factors, such as age and cigarette smoking was obtained on 144 nuclear power plant workers and 32 hospital workers, by a self-administered questionnaire. Information on physical exposure levels was obtained from the registries of radiation exposure monitoring and control at each facility. The GPA mutant assay was performed using the BR6 method with modification by using a FACScan flow cytometer. Results : As confounders, age and cigarette smoking habits showed increasing trends with GPA variants, but these were of no statistical significance. Hospital workers showed a higher frequency of the GPA variant than nuclear power plant workers in terms of the NO variant. Significant dose-response relationships were obtained from in simple and multiple linear regression models. The slope of the regression equation for nuclear power plant workers was much smaller than that of hospital workers. These findings suggest that there may be apparent dose-rate effects. Conclusion : In population exposed to chronic low-dose radiation, the GPA assay has a potential to be used as an effective biologic marker for assessing the bone marrow cumulative exposure dose.

• Journal of Environmental Health Sciences
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• v.37 no.2
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• pp.81-93
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• 2011

Although pesticides have increased crop production and controlled disease, they have produced a number of adverse health effects. Pesticides have potential human toxicity and a variety of groups, such as farmers or industrial workers, as well as the general population, are exposed to pesticides. The purpose of this article, therefore, is to provide an overview of pesticide exposure and health through a literature review, focusing on exposure assessment, acute poisoning, chronic health effects, and future research needs. The exposure types and levels of pesticides vary by study subjects and need to be assessed by integrating several methods focused on the epidemiological purpose. Acute pesticide poisoning is a major public health problem in the world. Paraquat is the main causative pesticide for acute poisoning in Korea and should be banned in order to save several thousands of lives every year. Occupational pesticide exposure also causes numerous chronic diseases among farmers and industrial workers, including cancers, respiratory diseases, depression, retinal degeneration, diabetes, and abnormal menstrual cycle. However, controversy exists regarding the long-term effects of low-dose environmental pesticide exposure. The area of pesticide study is relatively new with broad study populations and it has received little academic and policy attention, particularly in Korea. More detailed studies investigating the risk of pesticide-related health effects and intervention efforts to reduce the problems are needed in Korea.

• Journal of Nutrition and Health
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• v.27 no.1
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• pp.12-22
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• 1994

Effects of very low level of lead in diet and exposure time on the accumulation and distribution in organs and tissues was investigated with growing rats. 21 days old Sprague-Dawley rats were exposed to lead for 7, 14 and 21 days by feeding of 0.03, 0.42, 0.92 and 1.46mg/kg Pb as Pb-acetate containing diet, respectively. Lead concentrations in blood, liver, kidney and bone exhibit a linear relationship with lead levels in diet. After 7 days of exposure, the greatest dose dependent accumulation of lead was found in kidney and followed in bone. However, after 14 and 21 days, the dose dependent accumlation of lead in bone was about two fold greater than that in kidney. The accumulation of lead in liver and blood was relatively low. As continuous exposure to lead, the concentrations of lead in liver, kidney, blood and intestinal tracts were rather not increased with exposure time. However, bone lead concentration was increased with exposure time by feeding of 0.92 and 1.46mg/kg Pb in diet, but not 0.42mg/kg. The lead concentration in gastrointestinal tracts tends also to increasing with lead levels in diet after 7 and 14 days of exposure. However, by 21 days of exposure the lead concentration revealed relatively constant value regardless of the dietary lead levels. It is concluded that the binding capacity of the lead in blood, liver, kidney and bone seems to be increased with increasing lead levels in diet. The lead concentration in these organs, with the exception of the lead in bone, seems, however, to be standing under steady state regulation by continued exposure with the same dietary lead level. Therefore, by chronic exposure condition with environmental relevant lead level bone might be a principle targe organ for lead and blood lead repesents better the current lead exposure than the lead body burden.

• Korean Journal of Environmental Biology
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• v.21 no.4
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• pp.321-327
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• 2003

Differences between the principles for the radiological protection of man and the environment are compared. The derived levels of exposure for man and biota recommended by the international agencies with dose rates for chronic radiation producing effects at different levels of biological organization were given in terms of the biological effects. Cytogenetic effects on plants after an exposure to ionizing radiation at low doses alone and in combination with other factors are discussed. A wide range of experimental data were analysed and the general conclusions were extracted to cover the topics such as non-linearity of dose response, synergistic and antagonistic effects of the combined exposure of different factors, radiation-induced genomic instability, and the phenomena of radioadaptation.

• Development and Reproduction
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• v.23 no.3
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• pp.263-275
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• 2019

Based on our preliminary results, we examined the possible role of low-dose and chronic-exposing of the chemicals those are known as endocrine disrupting chemical (EDC), on the proliferation of uterine endometrium and the localization of steroid receptors. Immunohistochemical or immunofluorochemical methodology were employed to evaluate the localization of antigen identified by monoclonal antibody Ki 67 protein (MKI67), estrogen receptor 1 (ESR1), estrogen receptor 2 (ESR2), and progesterone receptor (PGR). In $133{\mu}g/L$ and $1,330{\mu}g/L$ di(2-ethylhexyl) phthalate (DEHP) and $50{\mu}g/L$ nonylphenol (NP) groups, the ratio of MKI67 positive stromal cells was significantly increased but not in $500{\mu}g/L$ NP group. The ratios of MKI67 positive glandular and luminal epithelial cells were also changed by the chronic administration of NP and DEHP in tissue with dose specific manner. ESR1 signals were localized in nucleus in glandular and luminal epithelia of control group but its localization was mainly in cytoplasm in DEHP and NP administered groups. On the other hand, it was decreased at nucleus of stromal cells in $1,330{\mu}g/L$ DEHP group. The colocalization patterns of these nuclear receptors were also modified by the administration of these chemicals. Such a tissue specific and dose specific localization of ESR2 and PGR were detected as ESR1 in all the uterine endometrial tissues. These results show that the chronic lows-dose exposing of NP or DEHP modify the localization and colocalization of ESRs and PGR, and of the proliferation patterns of the endometrial tissues.

• Biomedical Science Letters
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• v.26 no.4
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• pp.249-255
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• 2020

Radiation therapy is one of the primary options for the treatment of malignant tumors. Even though it is an effective anti-cancer treatment, it can cause serious complications owing to radiation-induced damage to the normal tissue around the tumor. It was recently reported that normal stem cell response to the genotoxic stress of ionizing radiation can boost the therapeutic effectiveness of radiation by repairing damaged cells. Therefore, we focused on annexin A-1 (ANXA1), one of the genes induced by low-dose irradiation, and assessed whether it can protect adipose-derived stem cells (ADSCs) against oxidative stress-induced damage caused by low-dose irradiation and improve effectively cell survival. After confirming ANXA1 expression in ADSCs transfected with an ANXA1 expression vector, exposure to hydrogen peroxide (H2O2) was used to mimic cellular damage induced by a chronic oxidative environment to assess cell survival under oxidative conditions. ANXA1-transfected ADSCs demonstrated that increased viability compared with un-transfected cells and exhibited enhanced anti-oxidative properties. Taken together, these results suggest that ANXA1 could be used as a potential therapeutic target to improve the survival of stem cells after low-dose radiation treatment.

• Journal of Radiation Protection and Research
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• v.38 no.4
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• pp.166-171
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• 2013

While high-dose ionizing radiation results in long term cellular cytotoxicity, chronic low-dose (<0.2 Gy) of X- or ${\gamma}$-ray irradiation can be beneficial to living organisms by inducing radiation hormesis, stimulating immune function, and adaptive responses. During chronic low-dose-rate radiation (LDR) exposure, whole body of mice is exposed to radiation, however, it remains unclear if LDR causes changes in gene expression of the whole brain. Therefore, we aim to investigate expressed genes (EGs) and signaling pathways specifically regulated by LDR-irradiation ($^{137}Cs$, a cumulative dose of 1.7 Gy for total 100 days) in the whole brain. Using microarray analysis of whole brain RNA extracts harvested from ICR and AKR/J mice after LDR-irradiation, we discovered that two mice strains displayed distinct gene regulation patterns upon LDR-irradiation. In ICR mice, genes involved in ion transport, transition metal ion transport, and developmental cell growth were turned on while, in AKR/J mice, genes involved in sensory perception, cognition, olfactory transduction, G-protein coupled receptor pathways, inflammatory response, proteolysis, and base excision repair were found to be affected by LDR. We validated LDR-sensitive EGs by qPCR and confirmed specific upregulation of S100a7a, Olfr624, and Gm4868 genes in AKR/J mice whole brain. Therefore, our data provide the first report of genetic changes regulated by LDR in the mouse whole brain, which may affect several aspects of brain function.

• Journal of Multimedia Information System
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• v.7 no.2
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• pp.189-196
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• 2020

We have developed a device for recording biological data by inserting three electrodes and a needle with an angular velocity sensor into the moth for the purpose of measuring the electromyogram of the flapping and the corresponding lift force. With this measurement, it is possible to evaluate the moth-physiological function of moths, and the amount of pesticides that insects are exposed to (currently LD50-based standards), especially the amount of chronic low-concentration exposure, can be reduced the dose. We measured and recorded 2-channel electromyography (EMG) and angular velocity corresponding to pitch angle (pitch-like angle) associated with wing flapping for 100 sweet potato hawkmoths (50 females and 50 males) with the animals suspended and constrained in air. Overall, the angular velocity and amplitude of EMG signals demonstrated high correlation, with a correlation coefficient of R = 0.792. In contrast, the results of analysis performed on the peak-to-peak (PP) EMG intervals, which correspond to the RR intervals of ECG signals, indicated a correlation between ΔF fluctuation and angular velocity of R = 0.379. Thus, the accuracy of the regression curve was relatively poor. Using a DC amplification circuit without capacitive coupling as the EMG amplification circuit, we confirmed that the baseline changes at the gear change point of wing flapping. The following formula gives the lift provided by the wing: angular velocity × thoracic weight - air resistance - (eddy resistance due to turbulence). In future studies, we plan to attach a micro radio transmitter to the moths to gather data on potential energy, kinetic energy, and displacement during free flight for analysis. Such physiological functional evaluations of moths may alleviate damage to insect health due to repeated exposure to multiple agrochemicals and may lead to significant changes in the toxicity standards, which are currently based on LD50 values.

• Journal of Preventive Medicine and Public Health
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• v.27 no.3 s.47
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• pp.557-567
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• 1994

This study was conducted to examine the effect of chronic low dose organic solvent exposures in the industries towards then neurobehavioral functions of workers. Subjective symptoms on neurobehavioral function as well as a visual reaction time test (Flicker test) were administered to 94 exposed and 162 unexposed workers in a oil refinery and some other auto-repair shops. The results obtained were as follows : 1. Symptom complaints were higher and Flicker test values were lower in exposed workers than in unexposed workers. 2. Flicker valus were Inversely correlated with urinary Hippuric acid concentration in exposed workers(r=-0.26, p<0.05). 3. Flicker valus were inversely co..elated with Subjective symptom score(r=-0.15, p<0.05). Low Flicker value were also related with some subjetive symptoms such as 'Dimmed vision', 'Nightmare', 'Weakness on extrimity' in workers as a whole. While symptoms of 'Dimmed vision ', 'Nightmare' only observed among exposed workers.