• Journal of dental hygiene science
• /
• v.5 no.3
• /
• pp.105-112
• /
• 2005

In spite of relatively low level of radiation dose used at dental clinics, long term exposure may be harmful, so radiation workers at dental clinics must be well aware of its danger. This study was to analyze the factors to have an influence on safety management behavior in the radiography chamber by understanding the relationship among the knowledge, attitudes and behavior in regard with radiation safety management by dental hygienists in order to take preventive measures for dental hygienists and suggest ideas to develop radiation safety training programs. For this, we contacted dental hygienists working at the local dental clinics for 4 months from December of 2003 to march of 2004 and obtained the following findings. 1. Concering the knowledge level of radiation safety management, $8.59{\pm}2.36$ was average score with the highest of 13 and the lowest of 3 from 15-scale test. In addition, knowledge level of radiation safety management by general characteristics showed statistically significant difference according to working experience (p < 0.001), marital status (p < 0.001), attendance rate of radiation safety management training program (p < 0.001), and type of clinic (p < 0.001). 2. Concering the attitude level of radiation safety management, $4.08{\pm}0.50$ is average score with the highest of $4.31{\pm}0.73$ and the lowest of $3.82{\pm}0.89$ by item from 5-scale test. Besides, attitude level of radiation safety management by general characteristics showed statistically significant difference according to age (p < 0.001), working experience (p < 0.05), attendance rate of radiation safety management training program (p < 0.01), and type of clinic (p < 0.001). 3. Concering the behavior level of radiation safety management, $2.89{\pm}0.77$ is average score from 5-scale test, which was relatively low in comparison with the level of attitude and the highest score was $3.82{\pm}0.94$ and the lowest $2.37{\pm}1.04$ by item. Behavior level of radiation safety management by general characteristics showed statistically significant difference according to working experience (p < 0.001) and type of clinic (p < 0.001). 4. From the survey of relationship among knowledge, attitude and behavior of radiation safety management was, we found that the higher the knowledge level of radiation safety management, the higher the level of attitude and behavior, and the higher the attitude level was, the higher the level of behavior.

• Journal of Marine Life Science
• /
• v.2 no.1
• /
• pp.20-26
• /
• 2017

In this study, we evaluated the toxic effects of heavy metals (As, Cr and Pb) on the population growth rate (r) of the marine diatom, Skeletonema costatum. The r of the species was determined after 96 h (4 days) exposure to As (0, 0.31, 0.63, 1.25, 2.50 and 5.00 mg L^-1), Cr (0, 0.16, 0.31, 0.63, 1.25 and 2.50 mg L^-1) and Pb (0, 1.25, 2.50, 5.00, 10.00 and 20.00 mg L^-1). It was observed that r in the control (absence of As, Cr and Pb) were greater than 0.04, however suddenly decreased with increased heavy metal concentrations. As, Cr and Pb reduced r in a dose-dependent manner and a significant reduction were occurred at concentration of greater than 0.31, 0.31 and 5.00 mg L^-1, respectively. Based on the toxicity, the heavy metal were ranked as Cr>As>Pb, with EC₅₀ (50% effective concentration) values of 0.80, 2.57 and 13.88 mg L^-1, respectively. The lowest-observed-effective-concentration (LOEC) of r in exposed to As, Cr and Pb were 0.63, 0.63 and 10.00 mg L^-1, respectively. Precisely, a concentration of greater than 0.63 mg L^-1 of As, 0.63 mg L^-1 of Cr and 10.00 mg L^-1 of Pb in marine ecosystems induced toxic effect on the r of S. costatum. Based on our results, we suggested that the r of S. costatum might be a useful bio-indicator for the toxicity assessment of heavy metals on the producer in marine ecosystems.

• Proceedings of the Korean Environmental Health Society Conference
• /
• 2003.06a
• /
• pp.24-25
• /
• 2003

Lead is ubiquitous in the human environment as a result of industrialization. China's rapid industrialization and traffic growth have increased the potential for lead emissions. Lead poisoning in children is one of the most common public health problems today, and it is entirely preventable. Children are more vulnerable to lead pollution and lead in their bodies can affect their nervous, circulatory, and digestive systems. Children are exposed to lead from different sources (such as paint, gasoline, and solder) and through different pathways (such as air, food, water, dust, and soil). Although all children are exposed to some lead from food, air, dust, and soil, some children are exposed to high dose sources of lead. Significant sources of lead for China's children include industrial emissions (often close to housing and schools), leaded gasoline, and occupational exposure that occurs when parents wear lead-contaminated clothing home from work, burning of coal for home heat and cooking, contaminated food, and some traditional medicines. To assess the blood lead level in children in China, a large-scale study was conducted in 19 cities among 9 provinces during 1997 to 2000. There were 6502 children, aged 3-5 years, were recruited in the study The result indicates that the mean blood lead level was 8.83ug/dl 3-5 year old living in city area. The mean blood lead level of boys was higher than that of girls (9.1l ug/dl vs 8.73ug/dl). Almost 30 percent childrens blood lead level exceeded 10ug/dl. The average blood lead level was higher than that of in 1985 (8.83ug/dl vs 8.lug/dl). An epidemiological study was carried on the children living around the cottage industries recycling the lead from battery. Nine hundreds fifty nine children, aged 5-12 years, living in lead polluted villages where the lead smelters located near the residential area and 207 control children live in unpolluted area were recruited in the study. The lead levels in air, soil, drinking water and crops were measured. The blood lead and ZnPP level were tested for all subjects. The results show that the local environment was polluted. The lead levels both in the air and crops were much higher than that of in control area. In the polluted area, the average blood level was 49.6ug/dl (rang 19.5-89.3ug/dl). Whereas, in the unpolluted area, the average blood level was 12.4ug/dl (rang 4.6-24.8ug/dl). This study indicates that in some countryside area, some cottage industries induce seriously lead pollution and cause children health problem. For the introducing of unleaded gasoline in some large cities, such as Beijing and Shanghai, the blood lead level showed a declined trend since 1997. By 2000, the use of leaded gasoline in motor vehicles has been prohibited in China. The most recent data available show that levels of lead in blood among children in Shanghai decreased from 8.3ug/dl in 1997 to 7.6ug/dl in 1999. The prevalence rate of children lead poisoning (blood lead >10ug/dl) was also decreased from 37.8% to 24.8%. In children living in downtown area, the blood lead level reduced dramatically. To explore the relationship between gene polymorphisms and individual susceptibility of lead poisoning, a molecular epidemiological study was conducted among children living in lead polluted environment. The result showed that the subjects with ALAD2 allele has higher ZPP level, and the subjects with VDR B allele has larger head circumference than only with b allele. In the present study, we demonstrated that ALAD genotypes modify lead effects on heme metabolism and VDR gene variants influence the skull development in highly exposed children. The polymorphism of ALAD and VDR genes might be the molecular inherited factor modifying the susceptibility of lead poisoning. Recently, Chinese government pays more attention to lead pollution and lead poisoning in children problem. The leaded gasoline was prohibited used in motor vehicles since 2000. The government has decided to have a clampdown on the high-polluted lead smelters for recycling the lead from battery in countryside. It is hopeful that the risk of lead poisoning in children will be decreased in the further

• Radiation Oncology Journal
• /
• v.12 no.1
• /
• pp.27-31
• /
• 1994

There are a number of reports suggesting that there may be a correlation between the clinical response to radiotherapy in various tumors and the clonogenic survival of cell lines derived from these tumors following exposure to 2 Gy(SF2). Authors conducted this study to determine SF2 for cells in primary culture from surgical specimens. The tumor tissues with squamous cell carcinoma of uterine cervix and head and neck were obtained. The tumor tissues were disaggregated to single cells by incubating with collagenase type w for 2 hours with constant stirring. Single cell suspensions were inoculated in four 24-well plates precoated with cell adhesive matrix. After 24 hours of incubation at 37$ ^{\circ}C $, rows of four wells were then irradiated, consisting of control set and five other sets each receiving doses of 1,2,3,4, and 6 Gy. After incubation for a total of 13 days, the cultures were stained with crystal violet and survival at each dose was determined by quantitative image analysis system, To determine whether cell growth was of epithelial origin, immunocytochemical staining with a mixture of cytokeratin and epithelial monoclonal antibodies were performed on cell cultures. During the period of this study, we received 5 squamous cell carcinoma specimens of head and neck and 20 of uterine cervical carcinoma. Of these, 15 yielded enough cells for radiosensitivity testing. This resulted an overall success rate of 60$ \% $. The mean SF2 value for 15 tumours was 0.55$\pm$0.17 ranging from 0.20 to 0.79. These results indicate that there is a broad range of sensitivities to radiation in same histologic type. So with a large patient population, we plan to determine whether a different SF2 value is associated with tumours that are controlled with radiotherapy than those that are not.

• Journal of Life Science
• /
• v.23 no.2
• /
• pp.197-206
• /
• 2013

The present study investigated whether leukemia-maintaining cells reside in a differentiation-resistant fraction using a megakaryocytic differentiation model of K562 cells. Treatment with phorbol-12-myristate-13-acetate (PMA) significantly inhibited the colony-forming efficiency of the K562 cells. At a PMA concentration of 1 nM or higher, colony was not formed, but approximately 40% of K562 cells still survived in soft agar. Approximately 70% of colony-forming cells that were isolated following the removal of PMA after exposure to the agent were differentiated after treatment with 10 nM PMA for 3 days. The differentiation rate of the colony-forming cells was gradually increased and reached about 90% 6 weeks after colony isolation, which was comparable to the level of a PMA-treated K562 control. Meanwhile, imatinib-resistant variants from the K562 cells, including K562/R1, K562/R2, and K562/R3 cells, did not show any colony-forming activity, and most imatinib-resistant variants were CD44 positive. After 4 months of culture in drug-free medium, the surface level of CD44 was decreased in comparison with primary imatinib-resistant variants, and a few colonies were formed from K562/R3 cells. In these cells, Bcr-Abl, which was lost in the imatinib-resistant variants, was re-expressed, and the original phenotypes of the K562 cells were partially recovered. These results suggest that leukemia-maintaining cells might reside in a differentiation-resistant population. Differentiation therapy to eliminate leukemia-maintaining cells could be a successful treatment for leukemia if the leukemia-maintaining cells were exposed to a differentiation inducer for a long time and at a high dose.