• Title/Summary/Keyword: repeated exposure

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Effect of Lipopolysaccharide (LPS) Exposure on the Reproductive Organs of Immature Female Rats

  • Yoo, Da Kyung;Lee, Sung-Ho
    • Development and Reproduction
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    • v.20 no.2
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    • pp.91-99
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    • 2016
  • Lipopolysaccharide (LPS), an endotoxin, elicits strong immune responses in mammals. Several lines of evidence demonstrate that LPS challenge profoundly affects female reproductive function. For example, LPS exposure affects steroidogenesis and folliculogenesis, resulting in delayed puberty onset. The present study was conducted to clarify the mechanism underlying the adverse effect of LPS on the delayed puberty in female rats. LPS was daily injected for 5 days ($50{\mu}g/kg$, PND 25-29) to treated animals and the date at VO was evaluated through daily visual examination. At PND 39, animals were sacrificed, and the tissues were immediately removed and weighed. Among the reproductive organs, the weights of the ovaries and oviduct from LPS-treated animals were significantly lower than those of control animals. There were no changes in the weights of uterus and vagina between the LPS-treated and their control animals. immunological challenge by LPS delayed VO. Multiple corpora lutea were found in the control ovaries, indicating ovulations were occurred. However, none of corpus luteum was present in the LPS-treated ovary. The transcription level of steroidogenic acute regulatory protein (StAR), CYP11A1, CYP17A1 and CYP19 were significantly increased by LPS treatment. On the other hand, the levels of $3{\beta}$-HSD, $17{\beta}$-HSD and LH receptor were not changed by LPS challenge. In conclusion, the present study demonstrated that the repeated LPS exposure during the prepubertal period could induce multiple alterations in the steroidogenic machinery in ovary, and in turn, delayed puberty onset. The prepubertal LPS challenge model used in our study is useful to understand the reciprocal regulation of immune (stress) - reproductive function in early life.

The Optimization Experience of Occupational Exposure during Unclear Power Plant Outage (원자력발전소 계획예방정비 기간중 피폭최적화 경험)

  • Song, Young-Il;Kim, Hyung-Jin;Park, Hun-Kook;Kim, Hee-Geun
    • Journal of Radiation Protection and Research
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    • v.28 no.2
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    • pp.145-154
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    • 2003
  • By optimizing the radiation protection the collective dose and individual dose could be reduced during YGN #4 $5^{th}$ outage in 2001. The collective doses for the two high radiation jobs decreased to 85% and 65% of expected doses. The proportion of workers with low dose (below 1mSv) exposure increased 4% while the proportion of workers with over 3mSv and 5mSv exposure are decreased to 2%, 1% respectively. But none is exposed over 8mSv for the annual dose. To aid decision of utilizing the robot, cost- benefit analysis was performed and reasonable point was proposed to use the robot. For the first time job, repeated ALARA meeting and mock up training were implemented to set up working procedure by identifying the trouble. To easily set up standard procedure, mockup process was videotaped and reviewed during ALARA meeting. Monitoring is a good approach to chase radiological working condition such as working time, dose rate. behavior of workers, especially for high radiation work. Those data were estimated and adjusted from the stage of work planning to mock up. At the stage of actual work the monitoring data were compared to the estimation and recorded to database. This database will not only be used as a powerful tool for dose optimization at the following outage but also as a guideline to dose constraint set up for optimization for each specific situation.

Development and Evaluation of a Dust Generator Using Soil Samples (토양 분진발생장치의 개발과 평가)

  • Lee, Ji-Yeon;Lee, Ki-Young
    • Journal of Environmental Health Sciences
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    • v.36 no.5
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    • pp.383-390
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    • 2010
  • Exposure to fugitive dust can contribute to several respiratory health problems, and proper sampling of fugitive dust is necessary to assess exposure. However, field sampling of soil dust encounters problems from spatial and temporal differences in soil properties, field operations, and meteorological conditions. To minimize these problems, we designed a dust generator that simulates dust generation from soil. The dust generator consisted of a rotating chamber where soil samples were loaded and tumbled, and a settling chamber, where airborne soil dust samples were collected. As standard operating conditions, we decided on 2 g soil mass, 10 min sampling time, and 20 rpm rotating speed, with a flow rate of 30 l/min, based on three common soil textures of loam, sandy loam and silt loam. To evaluate optimal operating conditions, we used mixtures of Joomoonjin silica sand and clay. Although the average $PM_{10}$ concentration of Joomoonjin silica sand was low, dust concentrations were increased by an increased content of clay. The dust concentrations were consistent across repeated experiments, and showed similar concentration profiles during the sampling time with mixtures of clay and sand (coefficient of variation was $13.6{\pm}w;7.1%$). The results demonstrated that these standard operating conditions were suitable for the dust generator, which can be used to investigate variations in soil properties that affect dust production and potential potency of fugitive dust exposure.

Spatial pattern and surface exposure ages of cryoplanation surface at Mt. Moodeung (무등산 평활사면(cryoplanation surface)의 형성시기와 분포특성)

  • OH, Jong Joo;PARK, Seoung-Phil;SEONG, Yeong Bae
    • Journal of The Geomorphological Association of Korea
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    • v.19 no.1
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    • pp.83-97
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    • 2012
  • Slopes of Seoseokdea~ Jangbuljae, at Mt. Moodeung, appears repeatedly the cliffs are mostly greater than $70^{\circ}$, and the planations maintain around $5^{\circ}$ in general. They studied the creation of development environments, cryoplanation are mainly facing the southwest. It is assumed that rock falling had been wostly occurred under a periglacial environment through jointing due to repeated freezing and thawing. Planation at the bottom of Columnar joint are described structural benches. Movement precesses of planation matrix are solifluction or jelifluction. The result of age determination of the slopes in Jangbuljae tells that the upper part of Ibseokdae has been remaining exposed to the land surface from 110,000 year ago. The blocks in the bottom part has been exposed to the surface around 10,000 year ago while Jangbuljae has been exposed to the surface about 50,000 year ago. It was assumed that they moved to the current location since being separated from columnar joint after exposure to the surface.

Application of Total Variation Optimization for Reduction of Head CT Dose (두부 CT 선량감소를 위한 총변량 최적화의 적용)

  • Choi, Seokyoon
    • Journal of the Korean Society of Radiology
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    • v.12 no.6
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    • pp.707-712
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    • 2018
  • The number of CT examinations is increasing, and radiation exposure is also increasing. repeated tests can affect the lens and thyroid. In hospitals, there is a tendency to lack interest in major long-term radiation exposure compared to the interest in increasing image information and image quality with head CT. In this study, we analyzed the improvement of image quality by proposed method to the noisy CT images. The proposed denoising method total variance optimization only for the impulsive noise candidate pixels. Experimental results show that edge information is well preserved and impulse noise can be effectively removed. and worked very well for the images according to tube voltage and rotation time. applied to the clinical setting, it can be used as the lowest exposure condition without worrying about the image quality and it will be helpful for the CT application.

PM10 Exposure Characteristics During the Harvesting, Plowing, Sowing, Planting, and Decapitation Tasks of Agricultural Workplaces in South Korea (수확, 경운정지, 파종, 정식, 순지르기 작업에서 발생하는 PM10 노출 특성)

  • Jung, Wongeon;Seo, Mintae;Kim, Hyocher
    • Journal of Korean Society of Occupational and Environmental Hygiene
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    • v.32 no.2
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    • pp.137-145
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    • 2022
  • Objectives: This study aimed to identify PM10 mass concentration levels and conduct peak identification during five tasks in agricultural works. Methods: We investigated five agricultural tasks in 12 farms, which were harvesting, plowing, sowing, planting, and decapitation. All samples were measured by using the portable aerosol spectrometer(PAS 1.108) and the aerosol monitor(SidePak AM520). The collected data were compared with the national PM10 concentrations. They were calculated to descriptive statistics, independent t-test, or ANOVA, and the peak identification on time series graph. Results: The ten investigated farms showed no significant difference with the national PM10 concentrations, but the two greenhouses(AM, 143.31, 85.16 ㎍/m3) showed significant difference(p<0.05). As a result of the peak identification, the harvesting tasks showed repeated peak occurrence with the background concentration level of about 50 ㎍/m3. For plowing and sowing tasks, the peak occurred intermittently when the working was conducted near the sampling sites. Among the five tasks, the arithmetic mean of the harvesting task was 138.84±294.71 ㎍/m3, which was significantly higher than the other tasks(p<0.05). In addition, the case of using a tractor was higher than the case of not using the tractor(p<0.05), and the driver's seat showed the highest concentration(AM, 95.81 ㎍/m3). Conclusions: Works in greenhouses might have exposure to PM10, while outdoor works is similar to general atmospheric PM10 concentration levels. However, there is a possibility of intermittent exposure to high concentrations of PM10 depending on the characteristics of agricultural tasks.

Residual Level, Histology, and Blood Biochemistry of Tebuconazole: A Repeated Dose 28-Day Oral Toxicity Study in Pigs

  • Jeong, Jin Young;Kim, Minji;Park, Seol Hwa;Kim, Byeonghyeon;Oh, Sang-Ik;Kim, Eunju;Jung, Hyunjung
    • Food Science of Animal Resources
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    • v.42 no.4
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    • pp.712-722
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    • 2022
  • In this study, we investigated the residual properties of tebuconazole-treated pigs. Twenty pigs were treated with different concentrations (0.25, 1.25, 2.5, 12.5, and 25 mg/kg bw/d) of tebuconazole for 28 d. Blood biochemistry, histology, and residual levels were analyzed using the VetTest analyzer, Masson's trichrome staining kit, and liquid chromatography-mass spectrometry, respectively. The final body weights were not significantly different between the control and treatment groups. Alkaline phosphatase, blood urea nitrogen, cholesterol, and gamma-glutamyl transpeptidase levels were significantly different from those of the control after exposure for 14 d. However, alanine aminotransferase levels showed changes only after exposure to pesticides for 28 d. The biochemical parameters were separated during the experimental period (14 d versus 28 d) by principal component analysis. Based on variable importance plots, blood urea nitrogen/creatinine ratio, blood urea nitrogen, glucose, and gamma-glutamyl transpeptidase are candidate biomarkers for tebuconazole exposure. The residual levels were observed at T4 (12.5 mg/kg bw/d) and T5 (25 mg/kg bw/d) in the liver and fat tissues, respectively. Fibrosis increased in the liver, kidney, and fat tissues, depending on the tebuconazole concentration. In conclusion, the residue limits of tebuconazole and the physiological changes caused by dietary tebuconazole in pigs provide important information for establishing maximum residue limits of pork and pork products.

Use of autonomous maximal smile to evaluate dental and gingival exposure

  • Wang, Shuai;Lin, Hengzhe;Yang, Yan;Zhao, Xin;Mei, Li;Zheng, Wei;Li, Yu;Zhao, Zhihe
    • The korean journal of orthodontics
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    • v.48 no.3
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    • pp.182-188
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    • 2018
  • Objective: This study was performed to validate the autonomous maximal smile (AMS) as a new reference for evaluating dental and gingival exposure. Methods: Digital video clips of 100 volunteers showing posed smiles and AMS at different verbal directives were recorded for evaluation a total of three times at 1-week intervals. Lip-teeth relationship width (LTRW) and buccal corridor width (BCW) were measured. LTRW represented the vertical distance between the inferior border of the upper vermilion and the edge of the maxillary central incisors. Intraclass correlation coefficients (ICCs) for reproducibility, and the m-value (minimum number of repeated measurements required for an ICC level over 0.75), were calculated. Results: LTRW and BCW of the AMS were 1.41 and 2.04 mm, respectively, greater than those of the posed smile (p < 0.05), indicating significantly larger dental and gingival exposure in the AMS. The reproducibility of the AMS (0.74 to 0.77) was excellent, and higher than that of the posed smile (0.62 to 0.65), which had fair-to-good reproducibility. Moreover, the m-value of the AMS (0.88 to 1.05) was lower than that of the posed smile (1.59 to 1.85). Conclusions: Compared to the posed smile, the AMS shows significantly larger LTRW and BCW, with significantly higher reproducibility. The AMS might serve as an adjunctive reference, in addition to the posed smile, in orthodontic and other dentomaxillofacial treatments.

Effects on Patient Exposure Dose and Image Quality by Increasing Focal Film Distance in Abdominal Radiography (복부 일반촬영시 초점-필름간거리 변화가 피폭선량 및 화질에 미치는 영향)

  • Kim, You-Hyun;Kwon, Soo-Il
    • Journal of radiological science and technology
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    • v.21 no.1
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    • pp.52-58
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    • 1998
  • We can and must improve the diagnostic images using available knowledge and technology. At the same time we must strive to reduce the patient's integral and entrance radiation dose. Reducing the integral dose to the patient during the radiologic procedure is a primary concern of the patient, especially the pediatric patient, the radiologist and the technologist. A 100cm focal film distance generally is used for most over-table radiography. The early x-ray tubes and screen film combinations required long exposures, which often resulted in motion artifacts. But nowaday, we have the generators and x-ray tubes that can deliver the energy necessary in a very short time and the receptors that can record the information just as rapidly. And, we performed this studies to evaluate the patient exposure dose and the image quality by increasing focal film distance in diagnostic radiography. There are many factors which affected to exposure factor, but we studied to verify of FFD increase, only. Effect of increasing the focal film distance to a 140 cm distance was tested as follows; 1. The focal film distances were set at 100, 120, and 140cm. 2. A 18cm acryl(tissue equivalent) phantom was placed on the table top. 3. An Capintec 192 electrometer with PM 05 ion chamber was placed at the entrance surface of the phantom, and exposure were made at each focal film distances. 4. The procedure was repeated in the same manner as above except the ion chamber was placed beneath the phantom at the film plane. 5. Exit exposure were normalize to 8mR for each portions of the experiment. Based on the success of the empirical measurements, a detailed mathematical analysis of the dose reduction was performed using the percent depth dose data. The results of this study can be summerized as followings ; 1) Increasing FFD from 100 cm to 140 cm, we would create a situation that would have a significant effect on the overall quality of radiograph and achive the 17.42% reduction of entrance dose and the 18.95% reduction of integral dose that the patient receives. 2) Thickness of Al step wedge for equal film density increased with the long distance. 3) Increasing FFD, Magnification of image was lowered. 4) Resolution of image also increased with the FFD. As the results described above, we strongly recommend using the long FFD to provide better information for our patients and profession in abdomen radiographic studies.

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Photoimmunological and Photobiological Action of Infrared Radiation

  • Danno, Kiichiro
    • Journal of Photoscience
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    • v.9 no.2
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    • pp.194-196
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    • 2002
  • While ultraviolet radiation alters various cutaneous cell functions, little is known about photo-immunological and photobiological effects of infrared radiation (IR) on the skin except its local thermal effects. The fIrst part of this study demonstrated that single exposure of mouse skin to near IR (0.7 - 1.3 $\mu$m) reversibly suppressed the proliferating activity of the epidermis, the density of Langerhans cells, and the ability of skin to induce contact hypersensitivity reaction. The second part demonstrated that the rate of wound closure was significantly accelerated by repeated exposures in animal models. The production of transforming growth factor-$\beta$l and matrix metalloproteinase-2, which are responsible for the wound healing processes, was significantly upregulated by irradiation, as shown by enzyme immunoassay, zymography, and reverse transcription polymerase chain reaction. Thermal controls were negative. The results suggest that near-IR irradiation can modulate the epidermal proliferation and part of the skin immune system, and stimulate the wound healing processes, presumably by non-thermal effects.

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