Biomedical subjects

Joo-Young Lee

Publications and source records attributed to Joo-Young Lee.

10 recordsLinked to original sources

PubMed2006

Validity and reliability of an alginate method to measure body surface area.

The purpose of this study was to evaluate the validity and reliability of coating methods (plaster bandage, inelastic tape, and the alginate method) and an indirect method using a three dimensional (3D) whole body scanner. The surface area of geometric solids was measured five times using the three coating methods, and analyzed through 2D scanning and a planimeter. Second, to examine the accuracy of the alginate method more closely, the surface areas of boards with different surface properties at various inclines were measured and compared. Lastly, the surface area of a human arm was measured using the three coating methods and a 3D scanning method. The results are as follows: 1) The three coating methods were statistically valid and reliable for measuring the surface area of geometric solids. 2) The planimeter was rejected because the mean error was bigger than in 2D scanning. 3) The method showing the least error was the inelastic tape method, but that method was not recommended because it was too tiresome and laborious. 4) The greater the curvature and smaller the size of a geometric solid, the greater the error. 5) In measuring surface area using the alginate method, the objects that were smoother and had steeper angles showed a greater surface area: however, the mean error was less than 1%. 6) In measuring a human arm, the surface area obtained by 3D scanning was less than any other surface area obtained in the three coating methods, because the 3D scanner could not discern the armpit and fingers. In conclusion, the method using alginate was statistically valid and reliable in the measuring of surface area both of geometric solids and real human skin.

Anthropometry↗

PubMed2004

Inhibition of trypsin-induced mast cell activation by water fraction of Lonicera japonica.

Lonicera japonica Thunb.(Caprifoliaceae) has long been known as an anti-inflammatory. In the present study, the effect of water fraction of Lonicera japonica (LJ) on trypsin-induced mast cell activation was examined. HMC-1 cells were stimulated with trypsin (100 nM) in the presence or absence of LJ (10, 100, and 1000 microg/mL). TNF-alpha and tryptase production were measured by enzyme-linked immunosorbent assay (ELISA) and reverse transcription-PCR. Extracellular signal-regulated kinase (ERK) phosphorylation was assessed by Western blot. Trypsin activity was measured by using Bz-DL-Arg-p-nitroanilide (BAPNA) as substrate. LJ (10, 100, and 1000 microg/mL) inhibited TNF-alpha secretion in a dose-dependent manner. LJ (10, 100, and 1000 microg/mL) also inhibited TNF-alpha and tryptase mRNA expression in trypsin-stimulated HMC-1. Furthermore, LJ inhibited trypsin-induced ERK phosphorylation. However, LJ did not affect the trypsin activity even 1000 microg/mL. These results indicate that LJ may inhibit trypsin-induced mast cell activation through the inhibition of ERK phosphorylation than the inhibition of trypsin activity.

Cell Line, Tumor↗

PubMed2003

Enantiomeric discrimination of pyrethroic acid esters on polysaccharide derived chiral stationary phases.

Enantiomeric separation of pyrethroic acid methyl and ethyl esters was examined on cellulose-based chiral stationary phases (CSPs): chiralcel OD (cellulose tris(3,5-dimethylphenyl carbamate)) and chiralcel OF (cellulose tris(4-chlorophenyl carbamate)). The good resolution of pyrethroic acid esters was achieved on chiralcel OD and OF. Separation factors ranged from 1.19-5.12 for Chiralcel OD and 1.00-1.59 for chiralcel OF. Hexane/2-propanol (100:0.15, v/v %) was used as the eluent. The resolution capability of CSPs was greater chiralcel OD than chiralcel OF in the case of the pyrethroic acid esters. The flow rate was 0.8 ml/min and detection was set at 230 nm. The results of the chromatographic data and molecular mechanics suggest that steric effect was a major factor in the enantioseparation. Furthermore, the hydrogen bond between analytes and CSP played an important role in the chiral recognition.

Hydrogen Bonding↗

PubMed2003

Enhanced menadione cytotoxicity in platelets isolated from streptozotocin-induced diabetic rats.

To study whether chemically induced cytotoxicity occurs in diabetic platelets, platelets isolated from rats made hyperglycemic (diabetic) by a prior intravenous administration of streptozotocin were incubated with menadione and the cytotoxicity was assessed by the amount of lactate dehydrogenase (LDH) released from the menadione exposed platelets as a function of time. Platelets isolated from diabetic rats released greater amount of LDH in response to menadione than those from normal rats. Consistent with this finding, induction of menadione cytotoxicity was not dependent on glutathione depletion, but on greater generation of free radicals in diabetic platelets. Greater sensitivity of diabetic platelets to the menadione-induced cytotoxicity was accompanied by release of serotonin from dense granules, suggesting that this mechanism contributes to cardiovascular diseases in diabetic subjects.

Animals↗

PubMed2003

Arsenic-induced dysfunction in relaxation of blood vessels.

Several epidemiological studies have suggested that exposure to arsenic is strongly correlated with the development of cardiovascular diseases such as hypertension. To determine whether arsenic affects vasomotor tone in blood vessels, we investigated the effect of arsenic on vasorelaxation using isolated rat aortic rings in an organ-bath system. Treatment with arsenite inhibited acetylcholine-induced relaxation of the aortic rings in a concentration-dependent manner, whereas several other arsenic species did not have any effect. Consistent with these findings, the levels of guanosine 3',5'-cyclic monophosphate (cGMP) in the aortic rings were significantly reduced by arsenite treatment. In cultured human aortic endothelial cells, treatment with arsenite resulted in a concentration-dependent inhibition of endothelial nitric oxide synthase (eNOS). In addition, higher concentrations of arsenite decreased the relaxation induced by sodium nitroprusside (an NO donor) and 8-Br-cGMP (a cGMP analog) in aortic rings without endothelium. These in vitro results indicate that arsenite is capable of suppressing relaxation in blood vessels by inhibiting eNOS activity in endothelial cells and by impairing the relaxation machinery in smooth muscle cells. In vivo studies revealed that the reduction of blood pressure by acetylcholine infusion was significantly suppressed after arsenite was administered intravenously to rats. These data suggest that an impairment of vasomotor tone due to arsenite exposure may be a contributing factor in the development of cardiovascular disease.

Animals↗

PubMed2003

Effects of thermal underwear on thermal and subjective responses in winter.

This study was conducted to obtain basic data in improving the health of Koreans, saving energy and protecting environments. This study investigated the effects of wearing thermal underwear for keeping warm in the office in winter where temperature is not as low as affecting work efficiency, on thermoregulatory responses and subjective sensations. In order to create an environment where every subject feels the same thermal sensation, two experimental conditions were selected through preliminary experiments: wearing thermal underwear in 18 degrees C air (18-condition) and not wearing thermal underwear in 23 degrees C air (23-condition). Six healthy male students participated in this study as experiment subjects. Measurement items included rectal temperature (T(re)), skin temperature (T(sk)), clothing microclimate temperature (T(cm)), thermal sensation and thermal comfort. The results are as follows: (1) T(re) of all subjects was maintained constant at 37.1 degrees C under both conditions, indicating no significant differences. (2) (T)(sk) under the 18-condition and the 23-condition were 32.9 degrees C and 33.7 degrees C, respectively, indicating a significant level of difference (p<0.05). (3) Among local skin temperature, trunk part (forehead and abdomen) did not show significant differences. After 90-min exposure, the skin temperature of hands and feet under the 18-condition was significantly lower than that under the 23-condition (p<0.001). (4) More than 80% of all the respondents felt comfortable under both conditions. It was found (T)(sk) decreased due to a drop in the skin temperature of hands and feet, and the subjects felt cooler wearing only one layer of normal thermal underwear at 18 degrees C. Yet, the thermal comfort level, T(re) and T(cm) of chest part under the 18-condition were the same as those under the 23-condition. These results show that the same level of comfort, T(re) and T(cm) can be maintained as that of an environment about 5 degrees C higher in the office in winter, by wearing one layer of thermal underwear. In this regard, this study suggests that lowering indoor temperature by wearing thermal underwear in winter can contribute to saving energy and improving health.

Adult↗

PubMed2003

Antithrombotic activity of LB30057, a newly synthesized direct thrombin inhibitor.

An amidrazonophenylalanine derivative, LB30057, inhibits the catalytic activity of thrombin potently by interaction with the active site of thrombin, and has high water solubility. In the present study, we evaluated the effect of LB30057 on the biological activities of thrombin at various tissues, and determined whether thrombin inhibition by LB30057 could reduce the incidence of occlusive thrombosis in an in vivo animal model. Treatment with LB30057 to human plasma prolonged clotting times in a concentration-dependent manner. LB30057 suppressed significantly thrombin-induced phosphatidylserine (PS) exposure in platelets, suggesting that LB30057 could inhibit blood coagulation accelerated by PS exposure. In human platelets, soluble thrombin- and clot-induced platelet aggregation was inhibited by LB30057 potently. Consistent with this finding, LB30057 showed concentration-dependent inhibitory effects on serotonin secretion and P-selectin expression induced by thrombin in platelets. In the blood vessel isolated from the guinea pig, treatment with LB30057 resulted in a concentration-dependent inhibition of thrombin-induced vascular contraction. In vivo study revealed that LB30057 following oral administration significantly increased the time to occlusion and improved carotid arterial patency using rat carotid artery thrombosis model. All these results suggest that LB30057 is a potent inhibitor of biological activities of thrombin at various target tissues and, therefore, might be developed as an antithrombotic agent for treatment and prevention of thrombotic diseases.

Administration, Oral↗

PubMed2002

Temperature-dependent quinone cytotoxicity in platelets involves arylation.

Menadione (MEN), a representative quinone compound, produces cytotoxicity in many cells by arylation with protein thiols and oxidative stress due to redox cycling. Previously it was demonstrated that protein arylation appears to be a primary mechanism for MEN-induced toxicity in platelets. To test the hypothesis that temperature conditions may be important in MEN-induced cytotoxicity in noncancer cells, platelets were incubated with menadione at 25, 37, or 42 degrees C. As temperature was increased, MEN significantly enhanced lactate dehydrogenase (LDH) leakage. MEN-induced depletion of protein thiol levels also increased as temperature was elevated. To investigate the mechanism of temperature-dependent MEN cytotoxicity, MEN-induced platelet toxicity was compared to two other quinone substances. Benzoquinone (BQ), which acts via arylation, produced cytotoxic effects similar to those of MEN. Dimethoxy-1,4-naphthoquinone (DMNQ), which exerts toxicity via oxidative radical generation, failed to produce cytotoxicity at all three temperatures. While MEN and DMNQ enhanced O(2) consumption in a temperature-dependent manner, BQ did not affect this parameter. MEN, which possesses an electrophilic 3-position, was found to react with thiols to form a thioether linkage, a direct indicator of arylation. In the case of MEN uptake kinetics, the amount of cellular uptake was not different at various temperatures, but concentration of MEN in extracellular medium decreased temperature dependently. This might be due to increased arylation capacity binding to cellular proteins as temperature rises. These data suggest that MEN-induced platelet cytotoxicity involves arylation that is temperature related.

Animals↗

PubMed2002

Enhancement of platelet aggregation and thrombus formation by arsenic in drinking water: a contributing factor to cardiovascular disease.

Arsenic in drinking water is a worldwide health problem that is associated with cardiovascular disease, but the cause is currently unknown. Arsenic effects on platelets, which are important in development of cardiovascular disease, were examined in vitro and in a drinking water study using a rat animal model. Trivalent inorganic arsenic (arsenite) induced in vitro aggregation when platelets were exposed to subthreshold challenge by thrombin and several other agonists in a concentration-dependent manner, with arsenite being the most potent form tested. Arsenite also induced significant increases in serotonin secretion, thromboxane A(2) formation, and adhesion protein expression in platelets. Consistent with the in vitro studies, 4-week ingestion of arsenite-contaminated drinking water resulted in enhanced arterial thrombosis. Human platelets showed similar responses, suggesting that the effects seen in animal experiments are applicable to humans. These results will provide new insights into the mechanism of arsenic-induced cardiovascular disease. They will also allow regulatory agencies to estimate risk from arsenic-induced cardiovascular disease and to determine if drinking water regulatory levels based on human cancer studies will protect against noncancer effects associated with cardiovascular disease.

Animals↗

PubMed2002

The roles of ATP and calcium in morphological changes and cytotoxicity induced by 1,4-benzoquinone in platelets.

To understand the mechanism of 1,4-benzoquinone-induced cytotoxicity in platelets, the roles of ATP and calcium in platelet toxicity and morphological changes were investigated. Using scanning electron microscopy, morphological changes including membrane blebbing were observed in rat platelets 5 min after exposure to 1,4-benzoquinone, which were significantly different from shape changes (pseudopod formation) observed in response to physiological agonists. Benzoquinone-induced membrane blebbing of platelets was associated with rapid depletion of intracellular ATP and was independent of the presence of extracellular calcium. Benzoquinone-induced platelet lysis observed between 20 and 30 min was dependent on extracellular calcium and associated with increased cytosolic calcium. Cytotoxicity induced by 1,4-benzoquinone was inhibited by antagonists of calmodulin, suggesting that calmodulin could play an important role in platelet toxicity. These results suggested that the progression of events for benzoquinone-induced cytotoxicity in platelets was as follows: 1,4-benzoquinone depletes intracellular ATP; membrane blebbing occurs; calcium homeostasis is disrupted, activation of calmodulin-dependent processes results; finally cytotoxicity occurs.

Adenosine Triphosphate↗