• 한국초등과학교육학회지:초등과학교육
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• 제25권4호
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• pp.396-406
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• 2006

In this study, elementary school students' science learning characteristics together with the levels of inquiry requirement in elementary school science experiment instruction were investigated in terms of the affective domain. We divided seventy-three students of the fifth ade into two groups according to the levels of inquiry requirement. After each instruction had been implemented, the characteristics of the students' learning in terms of the affective domain were compared and analyzed within the context of the levels of inquiry requirement. There were no significant differences between Level 1(LL) and Level 2(HL) groups in terms of the affective characteristics. These results may be caused by the burden imposed by the difficulty in thinking through and setting up the experimental methods. However, the HL group students' levels of interest in science experiments was higher than that of the LL group. In conclusion, the HL instruction contributed little to the improvement of affective characteristics. Some possible reasons might be that students felt difficulties with the somewhat unfamiliar instructions which required them to design and perform experiments. Higher levels of interest in science experiments amongst HL students' implies that well-organized and continuous exercises involving the design and performance of experiments could improve students' scientific affective characteristics.

• 대한예방의학회:학술대회논문집
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• 대한예방의학회 1994년도 교수 연수회(환경)
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• pp.549-559
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• 1994

A subgroup or workers from a secondary lead smelter was defined to include those with blood lead levels not exceeding $80{\mu}g/100\;ml$ and with no pest history of elevated blood lead. Central nervous system symptoms (tiredness, sleeplessness, irritability, headache) were reported by 55% of the group and muscle and joint pain by 39%. Zinc proteporphyrin (ZPP) levels were elevated in 71% or cases. Low hemoglobin levels (less than 14 gm/l00 ml) were round in more than a third of the workers. While BUN and creatinine were mostly in the normal range, there - nevertheless n correlation between ZPP and both BUN and creatinine. Reduced nerve-conduction velocities were present in 25% or the group; this was not significantly different from findings in Ii control group. The data indicate that n blood level of $80{\mu}g/100\;ml$ is an inappropriate biological guide in the prevention or lead disease.

• 한국학교보건학회지
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• 제14권2호
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• pp.269-277
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• 2001

This study examined the health conditions of schoolteachers in terms of the prevalence rate and risk factors for liver disease. A cohort design was conducted for 21,319 teachers who were born from 1953 to 1957. The cohort was constructed for teachers who had no disease history such as liver disease, hypertension, cerebral vascular disease, heart disease, diabetes mellitus and cancer, and had 'normal' results from liver disease examinations in 1998. They were followed up from 1998 to 2000. SAS 6.12 was used for the data analysis. The results were as follows; (1) Prevalence rates of liver disease per 1,000 people in 1998 were 43.0. (2) The 2-year cumulative incidence of liver disease was 433/16,103(26.9/1000 persons). (3) Factors such as sex, age, school type(private or public), drinking, smoking, exercise, BMI, weight gain, fasting-blood sugar levels and total cholesterol levels were statistically significant. The significant risk factors of liver disease be identified from the multiple logistic regression analysis were age, sex(male), drinking, smoking, BMI, weight gain, fasting-blood sugar levels, and total cholesterol levels.

• BMB Reports
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• 제44권7호
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• pp.473-477
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• 2011

Periodontitis is a very prevalent disease. Therefore, biomarkers for the early and standard diagnoses of periodontitis are urgently needed. TACE is a membrane-bound metalloprotease. Although a recent study suggested that TACE levels in GCF are elevated during periodontal disease, the levels of TACE in GCF at different stages of chronic periodontitis have not been determined. Here, we analyzed the protein levels of TACE in GCF from periodontal disease subjects and confirmed that the protein levels of TACE were higher in the moderate periodontitis groups. TACE is known to be a NF-${\kappa}B$ ligand that stimulates RANKL secretion in osteoblasts. To understand the effects of TACE on RANKL and OPG in osteoblasts, we treated MG63 cells with TACE. We observed an increase in RANKL protein expression but a decrease in OPG protein expression. Our data suggest that TACE can induce RANKL expression and promote osteoclastogenesis, thus worsening the outcome of periodontitis.

• BMB Reports
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• 제57권2호
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• pp.116-121
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• 2024

We investigated the therapeutic potential of bone marrow-derived mesenchymal stem cell-conditioned medium (BMSC-CM) on immortalized renal proximal tubule epithelial cells (RPTEC/TERT1) in a fibrotic environment. To replicate the increased stiffness characteristic of kidneys in chronic kidney disease, we utilized polyacrylamide gel platforms. A stiff matrix was shown to increase α-smooth muscle actin (α-SMA) levels, indicating fibrogenic activation in RPTEC/TERT1 cells. Interestingly, treatment with BMSC-CM resulted in significant reductions in the levels of fibrotic markers (α-SMA and vimentin) and increases in the levels of the epithelial marker E-cadherin and aquaporin 7, particularly under stiff conditions. Furthermore, BMSC-CM modified microRNA (miRNA) expression and reduced oxidative stress levels in these cells. Our findings suggest that BMSC-CM can modulate cellular morphology, miRNA expression, and oxidative stress in RPTEC/TERT1 cells, highlighting its therapeutic potential in fibrotic kidney disease.

• Journal of Nutrition and Health
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• 제31권7호
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• pp.1165-1173
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• 1998

The effect of oral iron supplementation was assessed on blood iron levels and Pb and Cd levels in erythrocytes, hair and urine of 101 Puchon 5th grade school children with suboptimal iron status. Treatment with 25mg of elemental iron per day for 8weeks resulted in a significant increase in the intake of most nutrients in addition to iron. Iron supplementation resulted in significant improvements in hemoglobin, MU, MCH, MCHC, serum ferritin, serum iron, TIBC, and transferrin saturation of subjects(p<0.05 - p<0.01) and cocomitantly lowered Pb and Cd levels in erythrocytes, hair, and urine(p<0.01). Regression analysis showed that only iron intake contributed to significant increases in hemoglobin and serum ferritin. It seems that 25mg of iron supplementation is safe and adequate to improve iron status in school children with suboptimal iron status and it also has the benefit of alleviating Pb and Cd status. (Korean J Nutrition 31(7) : 1165-1173, 1998)

• Molecules and Cells
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• 제42권2호
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• pp.97-103
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• 2019

Androgens act in almost all tissues throughout the lifetime and have important roles in skeletal muscles. The levels of androgens increase during puberty and remain sustained at high levels in adulthood. Because androgens have an anabolic effect on skeletal muscles and muscle stem cells, these increased levels of androgens after puberty should lead to spontaneous muscle hypertrophy and hyperplasia in adulthood. However, the maintenance of muscle volume, myonuclei number per myofiber, and quiescent state of satellite cells in adulthood despite the high levels of androgens produces paradoxical outcomes. Our recent study revealed that the physiological increase of androgens at puberty initiates the transition of muscle stem cells from proliferation to quiescence by the androgen-Mindbomb1-Notch signaling axis. This newly discovered androgen action on skeletal muscles underscores the physiological importance of androgens on muscle homeostasis throughout life. This review will provide an overview of the new androgen action on skeletal muscles and discuss the paradoxical effects of androgens suggested in previous studies.

• 한국수학사학회지
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• 제34권1호
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• pp.21-37
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• 2021

The purpose of the present study is to compare the differences in levels per group of high school students regarding the self-regulated learning factors for mathematics. For this purpose, a self-regulated learning measurement tool was developed and surveys were conducted. And the statistical analysis was completed using the frequency analysis, Kolmogorov-Smirnov normality test, Mann-Whitney U test and the Kruskal-Wallis H test. As a result, it is found that self-efficacy is of statistically significant differences in self-regulated learning levels regardless of the group classifications but test anxiety does not show statistically significant differences in self-regulated learning levels regardless of the group classifications.

• International Journal of Oral Biology
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• 제37권3호
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• pp.115-120
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• 2012

Retinoic acid plays an important role in the regulation of cell growth and differentiation. In our present study, we evaluated the effects of all-trans retinoic acid (RA) on cell proliferation and on the cell cycle regulation of human gingival fibroblasts (HGFs). Cell proliferation was assessed using the MTT assay. Cell cycle analysis was performed by flow cytometry, and cell cycle regulatory proteins were determined by western blot. Cell proliferation was increased in the presence of a 0.1 nM to 1 ${\mu}M$ RA dose range, and maximal growth stimulation was observed in cells exposed to 1 nM of RA. Exposure of HGFs to 1 nM of RA resulted in an augmented cell cycle progression. To elucidate the molecular mechanisms underlying cell cycle regulation by RA, we measured the intracellular levels of major cell cycle regulatory proteins. The levels of cyclin E and cyclin-dependent kinase (CDK) 2 were found to be increased in HGFs following 1 nM of RA treatment. However, the levels of cyclin D, CDK 4, and CDK 6 were unchanged under these conditions. Also after exposure to 1 nM of RA, the protein levels of $p21^{WAF1/CIP1}$ and $p16^{INK4A}$ were decreased in HGFs compared with the control group, but the levels of p53 and pRb were similar between treated and untreated cells. These results suggest that RA increases cell proliferation and cell cycle progression in HGFs via increased cellular levels of cyclin E and CDK 2, and decreased cellular levels of $p21^{WAF1/CIP1}$ and $p16^{INK4A}$.

• 한국환경보건학회지
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• 제37권2호
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• pp.94-101
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• 2011

Objectives: The purpose of this study is to evaluate the noise exposures of firefighters according to their time-dependent activity patterns. Methods: Personal exposure levels were measured for six days and nights using noise dosimeters; three days and nights for on-duty tasks, the other days and nights for off-duty activities. Results: The total amount of time spent in the workplace was 13,677 min (67%), outside areas 4,833 min (23%), in transit 1,002 min (5%), and other indoor area 807 min (4%) during a working period. However, during off-days they spent 10,858 min (76%) at home, 1,382 min (10%) outdoors, 1,225 min (9%) other indoors, and 493 min (3%) in transit. As a result of individual exposure levels, TWA did not exceed 90 dBA of the occupational exposure limit for the majority of the firefighters, whereas the levels of Lmax were 119 dBA, which were higher than the noise levels of firefighters in USA. Sometimes during dispatching the levels of Lpeak exceeded the ACGIH exposure standard (140 dBC). The Leq levels in transit were higher than the levels in home and other indoors even though the activity time is short. Conclusions: This paper characterized the noise exposure patterns of firefighters in Korea. We suggest that special noise sources, including sirens and speaker phones, should be readjusted to reduce noise exposure.