• 대한방사선기술학회지:방사선기술과학
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• 제41권6호
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• pp.611-616
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• 2018

Lead apron is harmful to the human body because it is made at heavy metals, and when worn for long periods of time, it causes pain. Therefore, this paper intended to improve the defects of lead apron by using new material shields. For the comparative evaluation of lead and new material shieldes, the shielding rate and weight were measured and tested based on lead 0.5 mmPb. The rate of shielding was 97% based on lead at 0.5 mm thickness, while The new material shield T3 showed similar shielding rates as lead in 8 layers, and in T2 these values were measured in 11 layers. In addition, similar shielding rate was measured in 12 layers at B2, and 8 layers in BF, and 4 layers in $BF_2$. Comparing the weight of cases when commercialized with apron, T3, T2 and B2 were heavier than lead apron. But BF, $BF_2$ were lighter than the lead apron. Based on the results of the experiment, T3 and T2 can be used as an alternative to lead if human or environmental hazards are considered a priority. However, BF and $BF_2$ should be used if the reduction of external exposure is considered a priority.

• Safety and Health at Work
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• 제9권4호
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• pp.473-478
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• 2018

Background: Multiple Chemical Sensitivity (MCS) is an acquired disease which etiology remains unknown. It is characterized by the development of sensitivity to certain chemical products. Most of the hypotheses formulated to explain the syndrome associate it to a previous exposition to some kind of volatile chemical. University researchers in chemical laboratories suffer a phenomenon of multi-exposition to chemical agents at low concentration during long periods of time although in an irregular form. Many of these chemical agents have similar properties to those suspicious of causing MCS. This article studies the prevalence of MCS in laboratory researchers. Methods: The study group is university researchers in chemical laboratories. The control group was obtained from administrative personnel who work in the same universities and therefore, are not exposed to chemical products from the laboratories, but have the same exposition to the rest of environmental polluting agents from the area and from the buildings of the university. In this study, it is used the Quick Environmental Exposure and Sensitivity Inventory (QEESI) (sensitivity of 92%/specificity of 95%). Results: The results showed that the prevalence of MCS for the university researchers is not related to exposition by inhalation to multiple chemical agents, at low concentration. Conclusions: The results disagree with one of the main etiological hypotheses of MCS, which is based on the existence of hypersensitive people, who presents a response after prolonged expositions to very low concentrations during a long period of time.

• Journal of Forest and Environmental Science
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• 제26권3호
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• pp.171-179
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• 2010

Effect of chromium (Cr) stress on antioxidant enzyme activities and malondialdehyde (MDA) content were investigated in leaves and roots of mangrove (italic (L.) Druce) seedlings. Cr toxicity effects were also assessed on young seedlings. The seedlings were grown in green house condition for three months in nutrient solution with 0, 0.5, 1, 1.5, 2, 2.5, and 3 mg $L^{-1}$ $CrCl_3$. This study showed that Cr led to the change of antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) and activities at different concentrations. The activity of antioxidant enzymes in leaves of K. candel seedlings indicates that enzymes engaged in antioxidant defense in certain level especially in low concentration of Cr treatments. The activities of SOD and POD were activated by Cr in the root level, while CAT activity was inhibited. CAT activity decreased in response to high concentrations of Cr. In the present study indicated that SOD in root was active in scavenging the superoxide produced by Cr. Both in roots and leaves, an increase in malondialdehyde (MDA) content was observed with increase in metal concentration and exposure periods. Our finding indicated that the high concentration of excessive Cr supply may interfere with several metabolic processes of seedlings, causing toxicity to plants as exhibited by chlorosis, necrosis, photosynthetic impairing and finally, plant death.

• The Korean Journal of Physiology
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• 제8권2호
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• pp.67-74
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• 1974

The object of this research is aimed to determine the activity of adenyl cyclase in both skeletal muscle sarcolemma and fat cell ghost of epididymal adipose tissue isolated from rats exposed to cold for various length of time in an attempt to evaluate whether the tissue sensitivity to catecholamine is increased when rats are exposed to cold for long periods of time Methods: a)Animals: Albino rats ranging in weight from 150 to 200 gm were used throughout this study. For experimental purposes, the rats are divided into two groups: experimental animals were place4 in a cold room at $4^{\circ}C$, controls being kept at $25^{\circ}C$. At the end of 2, 4, 6, 12, and 16 weeks. exposure to cold the rats were used to measure the adenyl cyclase activity. b) Isolation of plasma membrane from skeletal muscle and adipose tissue: The Plasma membrane of skeletal muscle from hind limbs of rats are prepared by the method employed by Rosenthal et at. and fat cell ghost of epididymal adipose tissue of rats by the method employed by Rodbell. c) Adenyl cyclase assay: Adenyl cyclase activity were measured by the method employed by Marinetti et al. Briefly, plasma membrane was incubated with $3^H-ATP$, various amount of noradrenaline and other incubation mixture at $37^{\circ}C$ for 20 minutes. After stopping the enzyme reaction by immersion in boiling water, carrier 3',5'-AMP was added to the system as a marker and $100\;{\mu}1$ aliquots of incubation mixture were pipetted on $20{\time}20$ Whatman No. 3 MM filter paper for one dimensional chromatography. The cyclic AMP spots were cut off and placed in counting vials containing 10ml of Bray's scintillation cocktail. Radioactivity was determined with a Packard Tri-Carb liquid scintillation counter. The enzyme activity is expressed as nanomoles of cyclic AMP produced per mg of membrane per hour. Result: 1. Average adenyl cyclase activity in the plasma membrane of skeletal muscle before and after noradrenaline administration was significantly higher in the cold-exposed rats as compared to the control. Continuous exposure to cold Produced an increased adenyl cyclase activity before and after noradrenaline administration. Adenyl cyclase activity reached peak levels at the 6 weeks exposure to told and level of adenyl cyclase activity remained high. Noradrenaline administration to the incubation medium induced a significant increase in adenyl cyclase activity and the degree of stimulation were proportional to the hormonal concentration But the rate of inclement in adenyl cyclase activity by noradreasline was the same in both groups. 2. Adenyl cyclase activity in fat cell ghost between cold exposed and control rats showed no significant differences before and after noradreualine administration. In summary, it can be concluded that cold adaptation give rise an increased activity of adenyl cyclase in plasma membrane of skeletal muscle in rats.

• 한국의료질향상학회지
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• 제10권2호
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• pp.190-203
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• 2003

Background: Dental hygienists are at risk of acquiring infections through exposure to infectious agents. This study explores the frequency of exposure to infectious agents and infection control practices among dental hygienists. Methods: We undertook a cross-sectional survey to examine the exposure to infectious agents and infection control practices among dental hygienists through questionnaire. Data were obtained from 124 dental hygienists attending educational conferences. A multiple logistic regression analysis was conducted to determine the factors that effect infection control practices in relation to age, completion of infection control education, recognition of their own serum hepatitis Ag/Ab status, the number of one day patients, location of clinics, type of clinics, and career years. Result: Of the 124 dental hygienists, 91.7% were exposed to at least one accident such as needle stick injuries during their practices periods. The health screening coverage rate in dental hygienists was 16.5%. The number of one day patients and career years were important in relation to infection control practices among dental hygienists. The adjusted odds ratio estimates for career years were 5.049 times greater(95% Cl 1.238-20.597) for groups with over 4 career years than under 2 career years. That for the number of one day patients were 0.261(95% Cl 0.071-0.955) lower for through 20 up to 30 patients, 0.531(95% Cl 0.102-2.78) lower for through 30 up to 40 patients and 0.498(95% Cl 0.123-2.017) lower for more than 40 patients than under 20 patients. Conclusion: From these results, prevalence of infection control practices among dental hygienists is related to the number of one day patients and career years. Prevention of cross infection and reduction of future transmission should be a priority to dental hygienists for promotion of infection control and further efforts to educate newcomers on infection prevention should be made.

• Journal of Radiation Protection and Research
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• 제37권2호
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• pp.96-102
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• 2012

2011년 국제방사선방호위원회(ICRP)는 최근 역학 조사들을 근거로 방사선영향으로 발생할 수 있는 암 외 질환의 위험에 대한 권고를 개정하였다. 특히 수정체 조직반응의 발단선량을 0.5 Gy로 하향 조정하면서, 계획 피폭상황에서 직무 피폭 시 수정체 등가선량한도를 "정해진 5년 기간 동안 평균해서 연간 20 mSv, 그 중 어느 한 해에도 50 mSv를 초과하지 않아야 한다"로 권고하였다. 방사선작업종사자의 외부선량은 개인 열형광선량계(TLD)를 사용하여 감시하고 있으며 판독한 열형광소자별 반응도를 선량평가 알고리즘에 적용하면 개인의 수정체 등가선량을 구할 수 있다. 본 논문에서는 성능검사에 사용된 Harshaw TLD의 소자반응도를 사용하여 현재 사용 중인 알고리즘들에 의한 수정체 등가선량을 평가하였다. 그 결과 성능검사에 사용된 TLD의 소자반응도를 사용하여 수정체 등가선량을 평가한 경우 알고리즘 간의 상대오차는 최대 48.84% 내에 있는 것으로 나타났다.

• Journal of Animal Science and Technology
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• 제63권6호
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• pp.1247-1264
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• 2021

Anabolic steroids are frequently used to increase the growth rate of meat-producing animals. Exposure to an anabolic-androgenic steroid, nandrolone decanoate (ND), is associated with expressional reduction of testicular steroidogenic enzymes. However, the effect of withdrawal of ND exposure on the expression of these testicular molecules has not been thoroughly explored. The current research investigated expression changes of testicular steroidogenic enzymes in rats at several recovery periods (2, 6, and 12 weeks) after the stop of ND treatment with different doses (2 and 10 mg/kg body weight) for 12 weeks. Body and testis weights were recorded, and transcript levels of molecules were determined by quantitative real-time polymerase chain reaction (PCR). The immunohistochemistry was used to examine the changes of immuno-intensities of molecules. At 6 and 12 weeks of the recovery period, the 10 mg/kg ND-treated rats were lighter than other experimental groups. The interstitial compartment vanished by ND treatment filled up as the recovery period became longer. The expression of steroidogenic acute regulatory protein was returned to the control level at 12 weeks of the recovery period. Expression levels of cytochrome P450 side-chain cleavage and 17a-hydroxylase were increased in 2 mg/kg ND-treated group at 6 weeks of the recovery period, and transcript levels of these molecules in 2 and 10 mg/kg ND-treated groups at 12 weeks of the recovery period were significantly lower than the control. Expression levels of 3β-hydroxysteroid dehydrogenase (HSD) type I and 17β-HSD type 3 in 2 mg/kg ND-treated group were comparable with those of control at 12 weeks of the recovery period, but not in 10 mg/kg ND-treated group. Expression of cytochrome P450 aromatase (Cyp19) was reverted to the control level at 2 weeks of the recovery period. Except for Cyp19, there was a visible increase of immuno-staining intensity of other testicular steroidogenic enzymes in the Leydig cells as the recovery period progressed. This research has demonstrated that the cease of ND administration could restore the expression of testicular steroidogenic enzymes close to the normal level. Nevertheless, a relatively long recovery period, compared to the ND-exposure period would be required to retrieve normal expression levels of testicular steroidogenic enzymes.

• Parasites, Hosts and Diseases
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• 제58권6호
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• pp.609-617
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• 2020

Plasmodium vivax reemerged in 1993. It has been sustained for more than 25 years and become one of the important indigenous parasitic diseases in northern and western parts of the Republic of Korea near the demilitarized zone. In particular, relapse is a significant concern for the control of malaria, as short- and long-term incubation periods vary among those infected in Korea. In this study, the prevalence of asymptomatic carriers was examined among residents of high endemic areas of vivax malaria during nonseasonal transmission of mosquitoes. Blood samples from 3 endemic regions in northwestern Korea were evaluated by microscopic examination, rapid diagnostic testing, and nested PCR to identify asymptomatic patients carrying malaria parasites in the community. However, no positive malaria case among residents of endemic areas was detected. Additionally, serological analysis was carried out to measure antibodies against 3 antigenic recombinant proteins of P. vivax, merozoite surface protein 1-19, circumsporozoite surface protein-VK210, and liver-stage antigen (PvLSA-N), by the protein array method. Interestingly, seropositivity of sera between previous exposure and samples without exposure to malaria was significantly higher using the PvLSA-N antigen than the other antigens, suggesting that PvLSA-N can be used as a serological marker to analyze the degree of exposure for malaria transmission in endemic areas. This indicates a very low asymptomatic carrier prevalence during the nonmalaria season in the endemic areas of Korea.

• 한국의학물리학회지:의학물리
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• 제11권2호
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• pp.123-130
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• 2000

전리계의 성능은 방사선 선량측정의 정확도와 정밀도에 직접적으로 영향을 준다. 본 연구에서는 전리계의 성능을 유지하기 위한 정도관리의 항목들을 제시하고 구체적인 성능검사를 시행하고자 한다. 선정된 성능평가 항목들은 적절한 인가전압, 예열 및 고전압 후의 평형시간, 누설에 의한 상쇄 전류, 방사선 측정 전후의 영점이동 (배경전류), 장시간 안정성, 선형성, 외부조건의 영향 등이었다. 전리계에 연결된 자루가 단단한 전리함과 방사선원으로 스트론티움-90이 내장된 검사기가 성능검사용으로 이용되었다. 인가전압의 측정은 전리함의 입력단자에서 직접 측정하였고 평형시간의 측정은 전리계에 전원을 연결한 후와 인가전압을 바꾼 후 검사기에 연결된 전리함의 반응이 안정을 가져오는 시간으로 측정하였다. 누설은 전리계가 안정된 후 방사선을 조사하지 않은 상태에서 전리계의 측정값이 영점에서 이동하는 것으로 나타냈으며 배경전류는 안정된 전리계의 영점을 조정하고 전리계에 연결된 검사기에서 전리함을 10분 조사한 후 영점의 변화로 나타냈다. 장시간의 안정성 3개월에 걸쳐 측정되었으며 이때 검사기의 측정값을 온도-기압에 대한 보정을 한 후 그 값을 비교하였다. 선형성은 전리계에 연결된 전리함을 n번 연속하여 조사하여 그 전체의 측정값과 초기값을 n번 곱한 값을 비교하였다. 외부조건의 영향은 인위적으로 외부온도를 17-34 $^{\circ}C$ 로 변화시켜서 환경변화에 의한 전리계의 영점이동으로 나타냈다. 인가전압의 측정에서 명목상의 인가전압 300, 500V에 대한 측정값은 각각 2.5%와 5.8% 작게 나타났다. 전원을 연결한 후 전리계가 실제로 평형에 도달하는 시간은 20분으로 이는 전리계의 안정성 표시기보다 9분 지연되었으며 인가전압을 바꾼 경우에는 1분 이내에 평형에 도달하였다. 전리계의 누설의 측정에서 영점의 이동은 0.002(스케일)/15분이었고 10분 조사 후 영점의 이동은 발견되지 않았다. 전리계는 3개월 동안 99.4%의 안정성을 유지하였다. 스케일 영역 0.000-9.991 에서 전리계의 선형성에서의 이탈은 0.9% 이었다. 온도 범위 17 - 34 $^{\circ}C$ 에서 전리계의 영점이동은 0.2% 이내였다. 본 연구에서는 임상에서 사용하고 있는 전리계에 대한 성능을 평가하는 항목을 제시하고 이를 전리계의 정도관리에 이용하도록 하였다. 이러한 프로그램의 운용을 통하여 전리계에 의한 오차를 줄임으로써 방사선측정에서의 정확도와 정밀도를 향상시킬 수 있을 것으로 사료된다.

• 치위생과학회지
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• 제14권1호
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• pp.7-14
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• 2014

구강 내 아말감 충전물에 의해 인체에 유리되는 수은이 요중 수은농도에 미치는 영향에 대하여 관련성을 평가하고자 하였다. 이 연구는 대도시 일부지역의 2개 초등학교 1~4학년 학생 317명을 대상으로 6개월 간격으로 총 4번의 구강검진과 소변검사를 실시하였으며, 자료를 수합하여 분석한 결과 다음과 같은 결론을 얻었다. 각 조사 시점별 아말감 충전 여부에 따라 요중 수은농도를 비교한 결과, 모든 연구시기에서 아말감 충전한 대상자에서 아말감 비충전군에 비해 요중 수은농도가 높게 나타났으며, 2차 추적조사와 3차 추적조사는 통계적으로 유의한 차이가 있었다. 혼합모형 분석한 결과 아말감 한 치면이 증가할수록 현재 요중 수은농도에서 $0.028{\mu}g/g$ creatinine 증가하였다(p<0.001). 남학생에 비해 여학생에서 $0.065{\mu}g/g$ creatinine (p<0.001), 생선섭취 빈도에서 일주일에 3회 이상 섭취군에서 $0.099{\mu}g/g$ creatinine 증가하였다(p=0.001). 누적 요중 수은농도에서 아말감 한 치면이 증가 할수록 누적 요중 수은농도에서 $0.017{\mu}g/g$ creatinine 증가 하였다(p<0.001). 남학생에 비해 여학생에서 $0.071{\mu}g/g$ creatinine (p<0.001), 생선섭취 빈도에서 일주일에 3회 이상 섭취군에서 $0.110{\mu}g/g$ creatinine 증가하였다(p<0.001). 구강 내 아말감 충전물은 미량이라도 수은을 유리시켜 체내 요중 수은농도의 변화에 영향을 미치므로 이 연구결과를 토대로 구강 내 수은흡수를 최소화할 수 있는 기준이나 방안이 마련되어야 할 것이다.