• Korean Journal of Environmental Biology
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• v.24 no.2 s.62
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• pp.102-111
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• 2006

The increased occurrence of hyperglycemia and oxidative stress in streptozotocin (STZ) induced type I diabetes has been implicated in the etiology and pathology of disease complication. STZ has known to be genotoxic in a variety of assays including tests for microbial mutagenesis and unscheduled DNA synthesis in rat kidney. Diabetes mellitus (DM) is a pathologic condition, resulting in severe metabolic imbalances and non-physiologic changes in many tissues. We examined the effect of gamma radiation and KWNP on preventing the development of insulin dependent diabetes mellitus using streptozotocin-induced Fisher 344 diabetic rats. The hematological values (red blood cell and white blood cell), serum biochemical constituents-alkaline phosphatase (ALP), total cholesterol, triglycerides and insulin-were checked and the organs (testis, spleen and kidney) were weighed. The gonad indices of the STZ treated groups were much lower than the value of the control group. But the gonad indices of the KWNP treated groups were higher than those of the treated groups. The ratio of the weight of kidney to the body weight of the STZ treated groups was higher than that of the control group. The value of the diabetic group treated with KWNP after irradiation (F group) was lower than the other STZ treated groups. The white blood cell and ALP values of the F group were lower than the other STZ groups, as well. The cholesterol and triglyceride values of all the KWNP treated groups were significantly lower than the other groups. A significant increase (about 10 times) of insulin was detected in the F group. The results of hematological assay showed the distinctive damage in the irradiated and STZ treated groups. The quantity of apoptotic cells in seminiferous tubule of testis confirmed a serious damage as assessed in the STZ treated groups. These experimental results have revealed that treatment of the products of KWNP after irradiation has the antidiabetic effect in the STZ-induced diabetic rats. But the F group showed higher recuperative power. These experimental results have revealed that treatment of the gamma irradiation and KWNP have the recovering effect in the STZ-induced diabetic rats.

• The Korean Journal of Pharmacology
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• v.30 no.1
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• pp.67-73
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• 1994

Na-Ca exchange transports calcium ion either into (reverse mode Na-Ca exchange) or out of the cell (forward mode Na-Ca exchange) according to the direction of driving force produced by the changes in ratio of intra- and extra-cellular Na concentrations. Thus, Na-Ca exchange is regarded as the regulator of myocardial contraction. However, the existence of reverse mode Na-Ca exchange and its role in myocardial contraction is still questioned. Present study was performed to identify the presence of reverse mode Na-Ca exchange and its possible involvement in the regulation of myocardial contraction in rat heart. Using the left atria of rat, contraction was induced by electrical field stimulation (EFS, 0.5 msec duration and supramaximal voltage). Changing of the stimulation frequencies from resting 4 Hz to 0.4, 1 or 8 Hz caused typical negative staircase effect in twitch tension, but $^{45}Ca$ uptake showed bimodal increase. When the stimulation frequency was abruptly changed from 4 Hz to 0.4 Hz the atrial twitch tension showed three phased-enhancement, that is, the initial rapid increase (the first phase) followed by rapid decrease (the second phase) and stabilization (the third phase). $^{45}Ca$ uptake was equivalent to tension, i.e. initial significant increase in first 30 second and then decrease. Benzamil treatment abolished the first phase of increase in a dose dependent manner from $10^{-5}\;to\;3{\times}10^{-4}M.$ Bay k 8644 $(3{\times}10^{-5}M)$ treatment enhanced the inotropy induced by frequency reduction and abolished the second and third phase decreases. Benzamil treatment also suppressed the contraction stimulated by Bay K 8644. Although the contraction at 4 Hz stimulation was completely abolished by verapamil $3{\times}10^{-5}\;M$ pretreatment, the contraction reappeared as soon as the stimulation frequency was changed into 0.4 or 1 Hz and interstingly,$^{45}Ca$ uptake were significantly higher than no treatment. From these results, it is concluded that reduction of stimulation frequency causes calcium influx by the reverse mode Na-Ca exchange, resulting in initial rapid increase of twitch tension. then it turns into forward mode exchange to efflux the calcium, resulting in decrease of the twitch tension in left atria of rat.

• Current Research on Agriculture and Life Sciences
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• v.6
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• pp.181-186
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• 1988

This experiment was conducted to examine the $PGF{2{\alpha}}$-induced changes in concentrations of ovarian and pituitary hormones of Korean native goats. Each goats received two injections of $PGF{2{\alpha}}$ (5mg each ; 3 hours apart) on day 10 of the estrous cycle. Jugular venous blood samples were collected at 0, 3, 6, 12, 24, 48 and 72 hours postinjection for quantification of LH, FSH, prolactin, progesterone and estradiol-$17{\beta}$. The results were summarized as follows ; The blood serum concentration of progesterone was decreased from pretreatment level of $4.15{\pm}1.8ng/ml$ to $2.52{\pm}1.2ng/ml$ (about 60%) within 3 hours and to $0.81{\pm}0.3ng/ml$ at 12 hours of the $PGF{2{\alpha}}$ injection. After 12 hours, the concentrations of progesterone were less than 1.02ng/ml by 72 hours postinjection. The concentrations of estradiol-$17{\beta}$ following treatment increased (p < 0.05) over the 72 hours. Initial concentration of LH was $3.0{\pm}0.3{\mu}IU/ml$. After treatment with $PGF{2{\alpha}}$, concentrations of LH increased within 12 hours but declined 12 and 72 hours from $4.1{\mu}IU/ml$ to $2.5{\mu}IU/ml$. Prior to administration of $PGF{2{\alpha}}$, mean concentration of FSH was $3.5{\pm}0.5{\mu}IU/ml$. Concentrations of FSH declined over time in goats treated with $PGF{2{\alpha}}$ on day 10 postestrus. The mean prolactin concentrations in the blood serum after $PGF{2{\alpha}}$ treatment were not significantly different from those of the pretreatment. It is concluded that the initial increase in LH is dependent on a decrease in serum progesterone and differences in patterns of secretion of gonadotropins might be caused by differences in progesterone or progesterone-estradiol ratio when luteal regression is induced on day 10 of the estrous cycle.

• Journal of Intelligence and Information Systems
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• v.21 no.2
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• pp.19-47
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• 2015

In this era of knowledge economy, a variety of virtual communities are proliferating for the purpose of knowledge creation and utilization. Since the voluntary contributions of members are the essential source of knowledge, member turnover can have significant implications on the survival and success of virtual communities. However, there is a dearth of research on the effect of membership turnover and even the method of measurement for membership turnover is left unclear in virtual communities. In a traditional context, membership turnover is calculated as the ratio of the number of departing members to the average number of members for a given time period. In virtual communities, while the influx of newcomers can be clearly measured, the magnitude of departure is elusive since explicit withdrawals are seldom executed. In addition, there doesn't exist a common way to determine the average number of community members who return and contribute intermittently at will. This study initially examines the limitations in applying the concept of traditional turnover to virtual communities, and proposes five membership fluidity measures based on a preliminary analysis of editing behaviors of 2,978 featured articles in English Wikipedia. Subsequently, this work investigates the relationships between three selected membership fluidity measures and group collaboration performance, reflecting a moderating effect dependent on work characteristic. We obtained the following results: First, membership turnover relates to collaboration efficiency in a right-shortened U-shaped manner, with a moderating effect from work characteristic; given the same turnover rate, the promotion likelihood for a more professional task is lower than that for a less professional task, and the likelihood difference diminishes as the turnover rate increases. Second, contribution period relates to collaboration efficiency in a left-shortened U-shaped manner, with a moderating effect from work characteristic; the marginal performance change per unit change of contribution period is greater for a less professional task. Third, the number of new participants per month relates to collaboration efficiency in a left-shortened reversed U-shaped manner, for which the moderating effect from work characteristic appears to be insignificant.

• The Korean Journal of Physiology
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• v.24 no.1
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• pp.27-37
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• 1990

The extrafetal transfer of $Li^{+}$ in amniotic fluid was studied in 45 pregnant rabbits. LiCl solution was administered either intravenously to mother or directly into the amniotic sac and monitored the appearance and disappearance of $Li^{+}$ in the amniotic fluid, then calculated the transfer rate of $Li^{+}$ of extrafetal origin. To study the transplacental $Li^{+}$ transfer, a solution of 150 mM LiCl was infused continuously via maternal vein (initial dose: 0.7 mmol/kg, maintaining dose: 0.03 mmol/kg/min) and the $Li^{+}$ concentration was measured in maternal blood and amniotic fluid after 60 and 120 minutes of infusion. Change in the volume of aminotic fluid was determined by Congo red dilution method at the same time. Effects of duration of gestation was not considered in this study. Extrafetal transport of $Li^{+}$ into the amniotic fluid was estimated by comparing the $Li^{+}$ concentration and volume of amniotic fluid determined before and after ligating the placental vessels. Extrafetal $Li^{+}$ transport from the amniotic fluid was determined by observing the time dependent disappearance of $Li^{+}$ and Congo red in amniotic fluid after injecting 0.5 ml solution of 15 mM or 90 mM LiCl and 50 mg/ml Congo red. Following are the results obtained: 1) During infusion of LiCl through maternal vein the ratio of the aminotic $Li^{+}$/maternal plasma $Li^{+}$ increased significantly along with the increment of fetal weight. 2) The volume of amniotic fluid of larger fetuses than 20.5 gm increased significantly during administration of LiCl while that of smaller fetuses did not change. 3) After umbilical cord ligation the $Li^{+}$ concentration of amniotic fluid of larger fetuses than 20.5 gm was decreased to $59.9{\pm}10.3%$ and $56.9{\pm}42.9%$ $(mean{\pm}S.D.)$ of those of control group after 60 and 120 minutes of LiCl infusion respectively. In amniotic fluid of smaller fetuses than 20.5 gm, there was no significant difference between control and ligation groups. 4) The disappearance rate of Congo red in the amniotic fluid was $45.2{\pm}8.2%/hr$. 5) The disappearance rate of $Li^{+}$ after intraamniotic injection of LiCl depended on the amount injected. On injecting $7.5\;{\mu}mol$ LiCl, $Li^{+}$ disappeared rapidly from the amniotic fluid and the rates after 60 min and 90 min were $97.0{\pm}2.8,\;98.5{\pm}2.0%$ respectively. On injecting $45\;{\mu}mol$ LiCl, the rates were $56.0{\pm}15.4,\;78.9{\pm}14.5%$ at 60 and 90 min. 6) From the above results it was concluded: a) $Li^{+}$ transfer into the amniotic fluid increased along with the fetal growth and one half of $Li^{+}$ influx is through the extrafetal route even after the maturation of fetal kidney. b) One half of the $Li^{+}$ transfer from the amniotic fluid was through swallowing of fetus, while the remaining half was transfered rapidly through amniotic membrane, which was concentration limited.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.38 no.1
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• pp.15-31
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• 2012

In our previous studies, the antioxidant, anti-aging, and antibacterial activities of Persicaria hydropipier L. extract, and the moisturizing effect of cream containing P. hydropipier extract were investigated. In this study, the cellular protective effects of P. hydropipier extract and isoquercitrin, main component from P. hydropipier in $^1O_2$-induced photohemolysis of human erythrocytes and ultraviolet B (UVB)-exposed HaCaT cells were investigated. Liposomes such as ethosome and elastic liposome for enhanced transdermal delivery were prepared. Size, loading efficiency, stability, and cumulative permeated amounts of ethosomes and elastic liposomes were evaluated. P. hydropipier extract and isoquercitrin showed more prominent cellular protective effect than (+)-${\alpha}$-tocopherol, known as lipid antioxidant at $5{\mu}g/mL$. P. hydropipier extract didn't show any characteristics of cytotoxicity at $50{\mu}g/mL$. When HaCaT cells were exposed to a single large dose ($400mJ/cm^2$) of UVB, the extract protected the cells against UVB radiation in a concentration dependent manner ($12.5{\sim}50{\mu}g/mL$). Cell viability of HaCaT cells exposed to UVB $400mJ/cm^2$ was increased by treatment with P. hydropipier extract or isoquercitrin from 36 % (cell viability of positve control groups) to 90 % (cell viability of P. hydropipier extract or isoquercitrin- treated groups). The size of 0.04 % P. hydropiper extract loaded ethosomes was 173.0 nm and the loading efficiency was 55.58 %. 0.04 % P. hydropiper extract loaded ethosomes were stable with as monodisperse particles for 1 week. The ethosome exhibited more skin permeability than general liposome and ethanol solution. The optimal ratio of lipid to surfactant ($Tego^{(R)}$ care 450) of 0.1 % P. hydropiper extract loaded elastic liposomes was observed to be 95 : 5. Vesicle size of 0.1 % P. hydropiper extract loaded elastic liposome was 176.5 nm. The deformability index of the elastic liposome was 16.4. The loading efficiency was 68.8 %. The elastic liposome containing P. hydropiper extract showed more skin permeability than liposome without surfactant ($Tego^{(R)}$ care 450).

• Korean Journal of Soil Science and Fertilizer
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• v.26 no.1
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• pp.37-42
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• 1993

Influences of metal concentration, pH and temperature on metal-ligand precipitate formation were investigated, as a part of projects for removing heavy metals from aqueous solution employing the principles in metal-ligand complexation. Aqueous solutions of HA or FA were reacted with those of heavy metals with 1:1 ratio. Efficiency of humic (HA) or fulvic acid (FA) on removing metals was evaluated by separating the precipitates from soltuions with the filtering method. When HA was a counter ligand, there existed three ranges of metal concentrations affecting precipitation : precipitate fromation was not available, was reached to the maximum, and afterwards was decreased again. The concentration ratios of metal to HA for initiating complexation were dependent upon kinds of metal and concentrations of ligand. Amount of Pb to form maximum precipitates per unit mg of HA was 1.3 times higher than that of Cu. When FA was a counter ligand, concentrations of metal-FA precipitates were increased proportionally with the treated metal concentrations. Efficiency of FA fro removing Pb was nearly 100%, but it was ranged from 12 to 19% for Cu, depending on FA concentration. pH exerted a considerable effect on complexation between Pb and FA, showing precipitates were increased six times at most per unit increase of pH. Ranges of pH increasing significantly the mounts of precipitates were coincied with pH jump ranges of the titration curve of organic ligands. As increasing temperature from 15 to $55^{\circ}C$, increases of FA-Cu precipitates were doubled, but those of FA-Pb were accounted for only 6%, However, HA-metal complexation was not affected by temperature.

• Management & Information Systems Review
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• v.36 no.4
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• pp.117-127
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• 2017

In recent times the size of the world IPO in general has skyrocketed. Specifically, China's financial market development is becoming important as both the size of China's capital market and the number of companies going public are gradually increasing. This has led to a rapid development of venture vapital(VC) institutions in China for the past couple of decades. This study focuses on one of the three markets of China's Shenzhen Stock Exchange-the Growth Enterprise Board((GEB) hereafter, ChiNext). The ChiNext is established in October, 2009 to enable hi-tech or high growth potential technology companies that find it relatively difficult to fulfil the listing requirements of either the Shenzhen Main Board or Small and Medium Size Enterprise Board(SMEB) to go public. This study covers a three-year period(2012/01/-2015/01) and analyze first day initial return of 83 venture capital-backed companies and 53 non-venture capital-backed companies using T-test. Regression analysis is used as to examine the variables affecting IPO's first-day return. The empirical results are four-fold. First, the level of first day return of venture-backed is significantly lower than non venture capital backed support in the Chinese venture capital market. Second, the level of first-day return of listed companies supported by foreign venture capital is significantly higher than that of companies receiving domestic venture capital support. Third, the firms that have a large number of venture capital firms showed a low level of first-day return. Fourth, regression result for the IPO first-day return which is as dependent variable indicates that the venture capital support(VCAP), number of venture capital(VCNum), offering size(Lnsize) and PER all affect have negative effect on the first day initial return. Also, the venture capital type(VCType), turnover ratio and the the firm type(Tech-firms) statistically affect IPO first day return positively. Finally, by shedding more light on the IPO first-day return, this paper provides meaningful information to investors about the Chinese IPO market.

• Journal of dental hygiene science
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• v.16 no.3
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• pp.217-224
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• 2016

The aim of this study was to evaluate whether the number of existing permanent teeth is associated with chronic obstructive pulmonary disease (COPD) in a representative sample of Korean adults. Data from 3,107 subjects who participated in the 2009 Korea National Health and Nutrition Examination Survey were examined. The dependent variable was COPD and the independent variable was the number of existing permanent teeth. Spirometry results were classified into three groups (normal pattern, restrictive pattern, and obstructive pattern) by trained technicians. We used dichotomized COPD variables (no vs. yes). The number of existing permanent teeth was evaluated by oral examination and divided into 3 groups (0~19, 20~27, and 28). Demographic factors (age group and sex group), socioeconomic status (education and income), health behaviors (smoking and drinking), oral health and behavior (frequency of toothbrushing; periodontitis; decayed, missing, filled, permanent teeth index; and denture status), and general health status (body mass index, diabetes mellitus, and hypertension) were included as confounders in the analysis. Bivariate analysis and multivariate logistic regression analyses including confounders were applied, and all analyses considered a complex sampling design. Stratified analysis was performed by smoking status. After controlling for various confounders, there was a significant association between the number of existing permanent teeth and COPD (odds ratio [OR], 1.90; 95% confidence interval [CI], 1.20~3.00 for the 20~27 group; OR, 3.93; 95% CI, 1.75~8.84 for the 0~19 group). The association was more significant in current smokers (OR, 8.90; 95% CI, 2.53~31.33). Our data indicate that the number of existing permanent teeth was independently associated with COPD, especially in current smokers. Further longitudinal research is needed to determine whether oral health promotion plays a role in the improvement of lung function and prevention of COPD.

• Journal of Aquaculture
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• v.9 no.2
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• pp.141-149
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• 1996

Effects of $17{\alpha}$-methyltestosterone ($17{\alpha}-MT$) in rearing water on sex reversal of Nile tilapia (Oreochromis niloticus) were investigated and optimum conditions as initial treatment time, concentrations and treatment durations of hormone were evaluated in this study. For the study of the optimum initial treatment time, 0 to 20-day-old fry were treated by immersion in a 500 ppb solution of $17{\alpha}-MT$. Desirable results were obtained at 12-day-old fish as $86.4\%$ of male induction rates and this frequency was obviously higher than the other age groups. Twelve-day-old fry were immersed in $17{\alpha}-MT$ solutions at concentrations of $0\~2,000$ ppb for 24 hours for the study of dose dependent relationship between sex ratios and concentrations of $17{\alpha}-MT$, Male induction rates of all treated groups were higher than $80\%$, $X^2$ values against the sex ratio of control group indicate that sex reversal has taken place effectively in all experimental groups (P<0.001). Futhermore, 500 ppb treated groups showed highest male incidence of $86.4\%$. Effects of 5 different durations (0, 12, 18, 24 and 30 hours) treated with 1,000 ppb of $17{\alpha}-MT$ were also evaluated. Male induction rate from 0 to 24 hours treated group was increased with treatment durations. However, male incidence of 30-hour treated group ($84.0\%$) was sligthly decreased compare to the 24-hour treated group ($85.2\%$). It is concluded that immersion treatment using $17{\alpha}-MT$ on O. niloticus is possible on sex reversal at low concentration of 500 ppb and short treatment durations within 24 hours with 12-old-day fry.