• Korean Journal of Remote Sensing
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• v.21 no.4
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• pp.253-271
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• 2005

We have analyzed surface water temperature and seasonal stratification of lakes in the Han river system using time-series Landsat images and in situ measurement data. Using NASA equation, at-satellite temperature is derived from 29 Landsat-5 TM and Landsat-7 ETM+ images obtained from 1994 to 2004, and was compared with in situ surface temperature on river-type dam lakes such as Paro, Chuncheon, Euiam, Chongpyong, Paldang, and with 10m-depth temperature on lake-type dam lake Soyang. Although the in situ temperature at the time of satellite data acquisition was interpolated from monthly measurements, the number of images with standard deviation of temperature difference (at-satellite temperature - in situ interpolated temperature) less than $2^{\circ}C$ was 24 on which a novel statistical atmospheric correction could be applied. The correlation coefficient at Lake Soyang was 0.915 (0.950 after correction) and 0.951-0.980 (0.979-0.997 after correction) at other lakes. This high correlation implies that there exist a mixed layer in the shallow river-like dam lakes due to physical mixing from continuous influx and efflux, and the daily and hourly temperature change is not fluctuating. At Lake Soyang, an anomalous temperature difference was observed from April to July where at-satellite temperature is $3-5^{\circ}C$ higher than in situ interpolated temperature. Located in the uppermost part of the Han river system and its influx is governed only by natural precipitation, Lake Soyang develops stratification during this time with rising sun elevation and no physical mixture from influx in this relatively dry season of the year.

• Korean Journal of Clinical Laboratory Science
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• v.53 no.2
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• pp.158-164
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• 2021

Hypertriglyceridemia is the main risk factor for atherosclerosis. It is reported that triglyceride (TG) induces macrophage cell death, and is involved in the formation of plaques and development of atherosclerosis. We previously reported that TG-induced cell death of macrophages is mediated via pannexin-1 activation, which increases the extracellular ATP and subsequent increase in potassium efflux, thereby activating the caspase-2/caspase-1/apoptotic caspases, including the caspase-8 pathway. Contrarily, some studies have reported that caspase-8 is an upstream molecule of caspase-1 and caspase-2 in several cellular processes. Therefore, this study was undertaken to investigate whether caspase-8 influences its upstream molecules in TG-stimulated macrophage cell death. We first confirmed that caspase-8 induces caspase-3 activation and poly ADP-ribose polymerase (PARP) cleavage in TG-treated macrophages. Next, we determined that the inhibition of caspase-8 results in reduced caspase-1 and -2 activity, which are upstream molecules of caspase-8 in TG-induced cell death of macrophages. We also found that ATP treatment restores the caspase-8 inhibitor-induced caspase-2 activity, thereby implying that caspase-8 affects the upstream molecules responsible for increasing the extracellular ATP levels in TG-induced macrophage cell death. Taken together, these findings indicate that caspase-8 potentiates the TG-induced macrophage cell death by activating its upstream molecules.

• Korean Journal of Agricultural and Forest Meteorology
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• v.25 no.2
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• pp.71-79
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• 2023

The quantification of soil respiration rates is important to understand carbon cycles of forest ecosystems. Soil respiration rates were assessed using Li-8100A soil flux system in one evergreen broadleaved (Quercus glauca Thunb.) and two coniferous (Cryptomeria japonica D. Don and Chamaecyparis obtusa Endl.) stands from May 2020 to April 2022 in southern Korea. Monthly variations of soil respiration rates were higher in the Q. glauca stand than in the C. japonica and the C. obtusa stands. The mean soil respiration rates were significantly higher in the Q. glauca stand (2.63µmol m^-2 s^-1) than in the C. japonica (0.93µmol m^-2 s^-1) and C. obtusa (0.99µmol m^-2 s^-1) stands. The three stands showed exponential relationships between soil respiration rates and soil temperature (R² = 0.44-0.80). The sensitivity of temperature (Q10 values) to soil respiration rates was highest in the Q. glauca stand (5.13), followed by the C. obtusa (3.10) and C. japonica (2.58) stands. These results indicate that soil respiration rates can be increased more in evergreen broadleaved stands than in coniferous stands under enhanced soil temperature.

• Korean Journal of Environmental Agriculture
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• v.22 no.1
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• pp.41-46
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• 2003

The suitability of the life Cycle Assessment (LCA) methodology to analyze the environmental impact of rice cultivation with different fertilizing systems is investigated. The arst part of an LCA is an inventory of parameters used and emissions released due to the system under investigation. In the following step, the Life Cycle Impact Assessment the inventory data were analyzed and aggregated in order to finally get one index representing the total environmental burden. For the life Cycle Impact Assessment (LCIA) the Eco-indicator 95 method has been chosen because this is well documented and regularly applied impact assessment method. The resulting index is called Eco-indicator value. The higher the Eco-indicator value the stronger is the total environmental impact of an analyzed fertilizing system. The rice field experiment conducted in middle parts of korea was chosen as an example for the life cycle impact analysis. In this experiment the treatments were consisted of none fertilizer plot (NF), standard fertilizer plot (SF) applied chemical fertilizers based on soil chemical analysis before rice transplanting, and efflux fertilized plot (EF) applied with pig wastes fermented as the same rates of SF plot as basis on total nitrogen content. The obtained Eco-indicator values were clearly different among the treatments in the rice trial. The total Eco-indicator values for SF and EF have been observed 58 and 38% relative to the NF, respectively. For all the treatments the environmental effects of eutrophication contributed most to the total Eco-indicator value. The results appeared that the LCA methodology is basically suitable to assess the environmental impact associated with different fertilizer applications for rice cultivation. A comparative analysis of the fertilizing system's contribution to global warming and eutrophication is possible.

• Journal of Life Science
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• v.27 no.1
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• pp.15-22
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• 2017

Streptococcus mutans (S. mutans), which plays a major role in the etiology of human dental caries, is able to tolerate exposure to acid shock in addition to its acidogenicity. We investigated the effects of pH stress on membrane fluidity, activities and expression levels of F-ATPase, and proton permeability in S. mutans. Using 1,6-diphenyl-1,3,5-hexatriene, we observed membrane ordering at pH 4.8 and pH 8.8. The ordering effects were larger at pH 4.8 in cytoplasmic membranes isolated from S. mutans (CMSM). Increasing pH resulted in a decrease in the activities and expression levels of F-ATPase. The proton permeability was decreased at both acidic and alkaline pHs, and the lowest permeability was observed at pH 4.8. The lower permeability at pH 8.8 than pH 6.8 is likely to be caused by the decreased proton influx due to the decreased CMSM fluidity. In addition, it seems to be evident that extremely low permeability at pH 4.8 was caused by the decreased proton influx due to the decreased CMSM fluidity as well as the increased proton efflux due to the increased activity and expression level of F-ATPase. It is likely that CMSM fluidity and F-ATPase activity are two major key factors that determine proton permeability in S. mutans. We suggest that CMSM fluidity plays an important role in the determination of proton permeability, which sheds light on the possibility of using nonspecific membrane fluidizers, e.g., ethanol, for anti-caries purposes.

• 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.

• The Korean Journal of Pharmacology
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• v.30 no.1
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• pp.29-37
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• 1994

Inhibition of the nociceptive Tail Flick Reflex (TFR) was observed with electrical stimulation of the locus coeruleus/subcoeruleus (LC/SC) in the male Sprague - Dawley rats under light anesthesia, and the involved neurotransmitter (s) were characterized. Electrical stimulation of LC/SC induced the analgesia with the stimulation threshold (intensity of the current, given for 100 usec and in 100 Hz frequency, which caused the TF latency longer than 6.5 sec) around 55 uA. Intrathecal administrations of ${\alpha}_2$ antagonist, yohimbine (30 ug) or opioid antagonist, naloxone (20 ug) increased the stimulation threshold by 147% and 123% respectively (from 55 uA to 135 uA,9 and from 54 uA to 123 uA;P0.01, n=5, each). The basal TF latency without stimulation (3.1 sec) was reduced by the antagonists (to 2.5 sec by yohimbine, p<0.05, n=5; to 2.6 sec by naloxone, p<0.1, n=5), vehicle only did not show any effect. Noradrenaline(NA) in the spinal cord superfusates measured with HPLC was increased by the LC/SC stimulation, from 4.18 ng/ml before to 7.74 ng/ml after stimulation (P<0.05, n=10). The result suggest that analgesia induced by LC/SC stimulation is mediated, at least in part, by the noradrenergic system in which ${\alpha}_2$ receptor is involved, as well as the opioid system.

• Journal of Yeungnam Medical Science
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• v.10 no.2
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• pp.432-444
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• 1993

Multidrug resistance(MDR) phenotype is frequently observed in animal and human cancer cell lines selected for in vitro resistance to a single chemotherapeutic agent. It is characterized by the diminished drug accumulation and is related to the drug efflux mechanism in resistant cells. In the present study, adriamycin resistant cells(L1210-$AdR_6$ : $10^{-6}M$ adriamycin, $-AdR_5$ : $10^{-5}M$) and vincristine resistant cells (L1210-$VcR_7$ : $10^{-7}M$ vincristine, $-VcR_6$ : $10^{-6}M$) were produced from mouse lymphoblastic leukemia cell line L1210. Growth profiles of survived cells were observed for 5 days with MTT(thiazolyl blue) assay and resistance was compared with $IC_{50}$(drug concentration of 50% survival reduction in absorbance). Resistant cells proliferated more slowly than sensitive cell. Doubling times were 29.7hr in L1210, 68.7hr in L1210-$AdR_5$ and 58.2hr in $-VcR_6$. MDRs expressed as resistance factor were as follows, L1210-$AdR_5$ was 76.4 times for vincristine, L1210-$VcR_6$ was 96.4 times for adriamycin. The cell membrane proteins with three different M.W. were recognized to be related resistance, 220, 158, and 88 kd in L1210-$AdR_5$, 158, 140 and 88 kd in L1210-$VcR_6$ by SDS-PAG electrophoresis. Cell surface membrane proteins were identified by radio-iodination and autoradiogram, their molecular weights were 158, 72.8, and 42.4 Kd in L1210-$VcR_6$.

• Clinical and Experimental Pediatrics
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• v.52 no.5
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• pp.588-593
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• 2009

Purpose : To investigate whether growth hormone (GH) has a protective effect on neurons in hippocampal slice cultures of neonatal rats exposed to oxygen-glucose deprivation (OGD). Methods : Cultured hippocampal slices of 7-day-old rats were exposed to OGD for 60 min. Then, the slices were immediately treated with three doses of GH (5, 50, or $500{\mu}M$) in media. The relative fluorescent densities of propidium iodide (PI) uptake in the slices and relative lactate dehydrogenase (LDH) activities in the media were determined and compared between each GH- treated group of slices and untreated slices (control) at 12 and 24 h after OGD. Immunofluorescent staining for caspase-3 and TUNEL staining were performed to observe the effect of GH on apoptotic neuronal death. Results : The relative fluorescent densities of PI uptake in CA1 and dentate gyrus (DG) of the hippocampal slices in each GH-treated group were not significantly different from those in the untreated slices at 12 and 24 h after OGD (P>0.05). Treatment with GH could reduce the relative LDH activities in the media of the GH-treated groups only at 12 h after OGD (P<0.05). Expression of caspase-3 and TUNEL positivity in CA1 and DG of the slices treated with 50-iM GH were not different from those of the untreated slices at 12 and 24 h after OGD. Conclusion : Treatment of hippocampal slice cultures with GH after OGD does not show a definitive protective effect on neuronal death but can reduce the LDH efflux of the slices in media at 12 h after OGD.

• The Korean Journal of Nuclear Medicine
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• v.30 no.4
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• pp.507-515
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• 1996

Background : Potassium channel opener (K-opener) opens ATP-sensitive K'-channel located at cell membrane and induces potassium efflux from cytosol, resulting in intracellular hyperpolarization. Newly synthesized K-opener is currently examined for pharmacologic potency by means of rubidium release test from smooth muscle strip pre-incubated with Rb-86. Since in-vivo behavior of thallium is similar to that of rubidium, we hypothesized that K-opener can alter T1-201 kinetics in vivo. Purpose : This study was prepared to investigate the effects of pinacidil (one of potent K-openers) on the T1-201 uptake and clearance in cultured myocyte, and in-vivo biodistribution in mice. Methods : Spontaneous contracting myocytes were prepared to imitate in-vivo condition from 20 hearts of 3-5 days old Sprague-Dawley rat and cultured for 3-5 days before use ($5{\times}10^5$ cells/ml). Pinacidil was dissolved in 10% DMSO solution at a final concentration of 100nM or l0uM and was co-incubated with T1-201 in HBSS buffer for 20-min to evaluate its effect on cellular T1-uptake, or challenged to cell preparation pre-incubated with T1-201 for washout study. Two, 40 or $100{\mu}g$ of pinacidil was injected intravenously into ICR mice at 10 min after $5{\mu}Ci$ T1-201 injection, and organ uptake and whole body retention rate were measured at different time points. Results : Co-incubation of pinacidil with T1-201 resulted in a decrease in T1-201 uptake into cultured myocyte by 1.6 to 2.5 times, depending on pinacidil concentration and activity of T1-201 used. Pinacidil enhanced T1-201 washout by 1.6-3.1 times from myocyte preparations pre-incubated with T1-201. Pinacidil treatment appears to be resulted in mild decreases in blood and liver activity in normal mice, in contrast, renal and cardiac uptake were mildly decreased in a dose dependent manner. Whole body retention ratios of T1-201 were lower at 24 hour after injection with $100{\mu}g$ of pinacidil than control. Conclusion : These results suggest that treatment with K-opener may affect the interpretation of T1-201 myocardial images, due to decreasing thallium accumulation and enhancing washout from myocardium.