• Development and Reproduction
• /
• v.25 no.4
• /
• pp.293-298
• /
• 2021

Di(2-ethylhexyl)phthalate (DEHP) could induce metabolic disorders through interfering with thyroid homeostasis. Therefore, we evaluated the effects of short term to environmental relevant doses of DEHP on thyroid hormones. Four week old Sprague-Dawley (SD) rats were treated with vehicle (corn oil), and DEHP 0.75, 7.5, and 150 mg/kg/day. The rats were treated with once daily by oral gavage and were sacrificed with after 1 week. They were measured body weight and relative thyroid weight, serum thyroid hormones and histological changes of thyroid. There was no difference in body weight between the control and DEHP exposed rats. Relative thyroid weight in DEHP 150 mg/kg/day treated group was significantly lower than control. Serum thyroxine levels was decreased in rats exposed to 0.75 and 150 mg/kg/day DEHP. No histological changes were observed in the thyroid of rats administered DEHP compared to control. Exposure to DEHP at environmental relevant levels, even short-term exposure, can cause hypothyroidism in adolescent rats even the exposure period is relative short.

• Asian Journal of Turfgrass Science
• /
• v.3 no.2
• /
• pp.83-88
• /
• 1989

This Study was designed to know the growth Status under various photoperiod using Zoysia matrella. The experimental plots were split into such groups as control (full sunlight) 3hour, 6hour and 9hour photoperiod by three replication of completely randomized design. Chlorophyll content was analyized by mackine method and total soluble sugar by anthrone method. The result obtained from this experiment was as fol1 lows ; l. Dry weight was high in the control and 9hour plots. Its decrease remarkably occured in the short day plots 2. Leaf growth woes remarkaly decreased by short day condition. Six hour was considered as critical duration for leaf growth. 3. The growth of rhizome in the 9hour and control plots was good. New development of rhizome in the' short day plots was very slow compare to the control plot. 4. Chlorophyll content was high at l8 days after transplanting and then decreased. Its content in the short day plots severely decreased. 5. The content of soluble sugar in the control was low at early growth stage and high at late growth stage. It was found that the shorter the exposure time to sunlight, the higher the ratio of sugar content.

• Korean Journal of Exercise Nutrition
• /
• v.15 no.4
• /
• pp.173-182
• /
• 2011

Post-traumatic stress disorder (PTSD) is a stress-related mental disorder induced by severe external stressors such as assault, disaster or severe accident. We investigated the effects of treadmill exercise on short-term memory in relation to apoptosis and cell proliferation in the hippocampus following PTSD. Stress to the pregnant rats was induced by exposure of maternal rats to the hunting dog in an enclosed room. Exposure time was 10 min, repeated three times per day, with 1 hour interval. Exposure of maternal rats to the hunting dog was continued 7 days after pregnancy until delivery. The pregnant rats in the exercise groups were forced to run on a treadmill for 30 min once a day for the same duration of stress exposure. Step-down avoidance task for short-term memory, western blot for Bcl-2, Bax, and immunohistochemistry for caspase-3, 5-bromo-2'-deoxyuridine (BrdU), and Ki-67 were conducted. Maternal rats exposed to stress during pregnancy showed short-term memory impairment. Expressions of Bax, Bcl-2, ratio of Bax to Bcl-2, and caspase-3 in the hippocampus were increased in the PTSD rats. Cell proliferation in the hippocampal dentate gyrus was decreased in the PTSD rats. Treadmill exercise alleviated short-term memory impairment and suppressed expressions of Bax, the ratio of Bax to Bcl-2, and caspase-3. Treadmill exercise also increased cell proliferation. The present results indicate that treadmill exercise alleviated PTSD-induced short-term memory impairment by suppressing apoptotic cell death and enhancing cell proliferation in the hippocampus.

• Horticultural Science & Technology
• /
• v.19 no.4
• /
• pp.560-563
• /
• 2001

To determine the minimum number of short day (SD) required for flower initiation and development of chrysanthemum, plants were exposed to SD and long day (LD) conditions. Floral development was significantly different between continuous exposure of 16 hour long day (LD) condition and 2 or 4 SD prior to LD in chrysan-themum cvs. Envy and Lady Time, respectively. As more SD exposure was given, final leaf number was decreased and floral stage was advanced, suggesting a facultative response to photoperiodic cycles. Therefore, only 2-4 days of SD were enough to induce flower initiation. After 6 weeks of SD condition, the plants continued anthesis regardless of subsequent photoperiods. The long day leaf number (LDLN) varied between cultivars as 38.0 and 45.4 in Envy and Lady Time, respectively.

• The Korean Journal of Pesticide Science
• /
• v.9 no.4
• /
• pp.347-353
• /
• 2005

Pesticide risk assessment for pesticide operators as well as for consumers has become one of the pesticide regulatory tools to reduce any unreasonable adverse health effects from pesticide use. The risk for pesticide operators can be quantified by comparing the acceptable operator exposure level(AOEL) with exposure level during pesticide application. This study is to evaluate the risk of benzimidazole fungicides application worker. The exposure level of pesticide applicators were calculated using Japanese operator exposure study tested with EPN 45% EC. The AOELs for pesticides were obtained dividing relevant lowest no observed abuse effect levels(NOAELs) for the exposure scenario into uncertainty factor, 100. For the non-cancer and cancer occupational risk assessment, $Q_1^*$ produced by US/EPA and life time average daily dose(LADD) calculated from average daily dose(ADD), treatment days per year, worked years for life time were used. Operator exposure for benzimidazole fungicides application were benomyl 0.2, carbendazim 0.36 and thiophanate-methyl 0.42 mg/kg/day. Short-term AOELs for benomyl, carbendazim and thiophanate-methyl were 0.3, 0.1, and 0.2 mg/kg/day, and long-term AOEL were 0.025, 0.025, 0.08 mg/kg/day, respectively. LADDs were benomyl 0.0038, carbendazim 0.0067, thiophanate-methyl 0.0081 mg/kg/day. The ratios of exposure to AOEL were $0.28{\sim}1.5$ for short-term and $3.73{\sim}9.88$ for long-term. Cancer risk for operator were $9.12{\times}10^{-6}$ for benomyl, $1.61{\times}10^{-5}$ for carbendazim and $1.13{\times}10^{-4}$ for thiophanate-methyl by the standard application scenario. The result showed 3 fungicides exceed the risk criteria, $1.0{\times}10^{-6}$. The above risk assessments were based upon conservative assumptions and therefore are believed to be protective of the applicator. To refine the risk at the more actual conditions, further risk assessment with more realistic data would be needed.

• Kosin Medical Journal
• /
• v.33 no.2
• /
• pp.171-180
• /
• 2018

Objectives: We investigated whether asthma attacks in asthmatic children were caused by short-term exposure to particulate $matter(PM)_{2.5}$. Methods: Subjects were 411 patients who received inhalation therapy in National Fukuoka Hospital, from March to May 2013. All subjects were outpatients. We surveyed the air quality measurement results in the stations closest to the address of the patients. Data were used from the City of Fukuoka website data on air pollution. We carried out a case-crossover study and compared $PM_{2.5}$ concentration between 7 days after asthma attack occurred and the day asthma attack occurred and 1, 2 and 3 days before asthma attack occurred. Results: Highest hourly concentration of the day (OR 1.013, 95%CI 1.000-1.025) showed a significant association with 1 day before $PM_{2.5}$ concentration statistically. And 0-1 year-old infants were more vulnerable to the highest concentration of 1 day before $PM_{2.5}$ concentration(P < 0.05). Average concentration of $NO_2$ and $O_3$ and asthma attack also showed a significant association. Conclusions: Maximal daily $PM_{2.5}$ concentrations within 24 hours prior to the attack affect asthma exacerbation. 0-1 year-old infants are particularly vulnerable to $PM_{2.5}$ concentration. Asthma exacerbation is aggravated by $NO_2$ and $O_3$ concentration on the day of the asthma attack.

• Journal of Preventive Medicine and Public Health
• /
• v.38 no.4
• /
• pp.465-472
• /
• 2005

Objectives : The aim of this study was to assess the effect of air pollution on the daily respiratory symptoms of elementary school children in Seoul. Methods : Using the panel study design, we collected diary data for the children's respiratory symptoms during the 1st day$\sim$15th day of April, July, October and December in 2003 among the 2nd and 3rd grade elementary school students. We merged the respiratory symptom data with the ambient air pollution data that was monitored by Ministry of Environment. Using a generalized estimate equation, we evaluated the relationship between the daily symptoms of the subjects and the exposure to ai r pollution after controlling for various potential confounders. Results : The nitrogen dioxide (NO2) exposure of the current day significantly increased the upper respiratory symptoms (adjusted odds ratio=1.12, 95% CI=1.01-1.24) and the lower respiratory symptoms (adjusted odds ratio=1.18, 95% CI=1.06-1.31) in the elementary school children. The sulfur dioxide (SO2) and carbon monoxide (CO) exposure in the current day was associated with the lower respiratory symptoms (adjusted odds ratio=1.12, 95% CI=1.01-1.25 for SO2; adjusted odds ratio=1.16, 95% CI=1.02-1.32 for CO). Conclusions : We found that exposure to air pollution affects the daily respiratory symptoms in children. This study suggests that the effect on children's health? due to the short term changes in air pollution levels needs to be considered as an important public health problem.

• Journal of Oral Medicine and Pain
• /
• v.35 no.1
• /
• pp.49-59
• /
• 2010

The purpose of this study was to investigate short-term masticatory muscle reactions in response to simulated noise and music sound. Hypothesis of this study was that loud noise would cause increased stiffness and decreased elasticity of the masticatory muscles compared to low level of noise or identical sound level of music. Fifteen male volunteers were recruited for the study. The sound levels of noise and music used here were 60 dB and 100 dB. The experiment comprised 4 sessions, Session 1 with 100 dB of noise for the 1st day of experiment: Session 2 with 100 dB of music for the $2^{nd}$ day: Session 3 with 60 dB of noise for the $3^{rd}$ day: Session 4 with 60 dB of music for the $4^{th}$ day. Stiffness and elasticity on the anterior temporalis and superficial masseter muscles were measured with tactile sensor before and 2, 4 and 6 minutes after exposure of sound. The study indicated that, in short-term exposure of sound, there was no significant difference between noise and music at both 60 and 100 dB of sound level, but that there were partially significant differences between 60 and 100 dB of sound level regardless of sound type. This suggest that high level of sounds like 100 dB used in this study, in spite of short term exposure of several minutes, would lead to masticatory muscle contraction, especially in the masseter muscles.

• Clinical and Experimental Pediatrics
• /
• v.61 no.5
• /
• pp.150-155
• /
• 2018

Purpose: Infantile spasms, also known as West syndrome, is an age-specific epileptic seizure. Most patients with this condition also exhibit delayed development. This study aimed to determine the effect of long-term prenatal stress on susceptibility to infantile spasms. Methods: We subjected pregnant rats to acute or chronic immobilization stress. Resulting offspring received N-methyl-D-aspartic acid (15 mg/kg, intraperitoneally) on postnatal day 15, and their behaviors were observed 75 minutes after injection. The expression of KCC2 and GAD67 was also determined using immunohistochemistry. Results: Exposure to long-term prenatal stress increased the frequency of spasms and decreased the latency to onset of spasms compared with offspring exposed to short-term prenatal stress. Expression of KCC2 and GAD67 also decreased in the group exposed to long-term prenatal stress compared with the group exposed to short-term prenatal stress. Conclusion: Our study suggests that exposure to long-term prenatal stress results in increased susceptibility to seizures.

• Tuberculosis and Respiratory Diseases
• /
• v.41 no.4
• /
• pp.328-338
• /
• 1994

Background: Effect of sulfur dioxide($SO_2$) exposure on airway is well known but little about the effect of $SO_2$ exposure on lung parenchyme. This study is to determine if short tenn exposure to $SO_2$ in concentration commonly found in industrialized environment cause potentially harmful effect on the lung parenchyme, and to evaluate the exposure time-response relationship between short tenn exposure to $SO_2$ and the inflammatory response in mouse lung. Method: 5ppm $SO_2$ gas was used and 48 mice were grouped into control(10), 30(9), 60(11), and 120 minute exposure(18) group. In each group, bronchoalveolar lavage(BAL) was done immediately after and at 1,2,3 days after exposure. Histological examination was performed in control and 120 minute exposure group. Results: 1) Cell response in bronchoalveolar lavage fluid. In 30 and 60 minute exposure group, compared to the control group, lymphocyte count has significantly increased(p<0.05) at 1 day after exposure but did not differ at 2 days after exposure. In 120 minute exposure group, also compared to the control group, there was significant increase in total cell, macrophage, and lymphocyte count at 1 day after exposure, (p<0.05) which lasted for 2 days but did not significantly differ at 3 days after exposure. 2) Histological findings in 120 minute exposure group. In the airway, mild epithelial cell damage and ciliary loss were noted but there was no evidence of inflammatory cell infiltration. Interstitial inflammatory infiltration was noted at 1 day after exposure, which lasted for 3 days after exposure and there was no evidence of edema or fibrosis in the interstitium Conclusions: These data indicate potentially noxious effect of $SO_2$ on the lung parenchyme as well as the airway at exposure level that are regarded as relatively safe, and the duration of injury depends on the exposure time.