• Korean Journal of Environmental Agriculture
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• v.37 no.3
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• pp.213-220
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• 2018

BACKGROUND: This study was carried out to determine characteristics of residual pesticides in time-dependent manner and calculate half-lives of the residual pesticides in fresh and dried Chinese matrimony vine. In addition, processing factors were calculated based on the residual concentrations in them. METHODS AND RESULTS: The test pesticides, etofenprox and fenitrothion, were sprayed onto the Chinese matrimony vine plants at once or twice (at seven-day interval) and then samples were collected at 0 (after 3 hours), 1, 3, 5 and 7 days after the last spraying. Dried samples were prepared in hot-air drying oven at $60^{\circ}C$ for 48 hours until water content of less than 20%. Residual concentrations of etofenprox in fresh and dried samples decreased by 54.0-60.9% after 7 days of the last pesticide-application. In case of fenitrothion, the concentrations were found to have decreased by 69.2-76.5%. Processing factors of etofenprox were 2.6-3.0 for the one-time spraying and 2.5-3.0 for the two-time spraying and those of fenitrothion were found to be 1.5-22 for the one-time spraying and 1.6-2.0 for the two-time spraying. First half-lives of etofenprox and fenitrothion in fresh and dried samples ranged from 5.0 to 6.3 and from 3.4 to 4.0 days, respectively. The third half-lives were found to be 15.0-18.9 and 10.2-12.1 days, respectively. CONCLUSION: Residual concentrations of the tested pesticides in the studied crop decreased, but those in the dried samples appeared to have increased. In addition, processing factor and half life were constant regardless of spraying times.

• Biomolecules & Therapeutics
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• v.8 no.2
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• pp.171-178
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• 2000

To evaluate the pharmacokinetic properties and tissue distribution of a newly developed recombinant human erythropoietin (GC-rhEPO), we analyzed the plasma and tissue levels of erythropoietin by an ELISA after intravenous (IV) and subcutaneous (SC) adminstration to the male rats at the doses of 20, 100, 500 or 2,500 unit/kg. After single IV bolus injection of GC-rhEPO, the plasma concentration was rapidly increased and decreased with two phases with half-lives of 13.4 min and 2.94 hours. AUC was increased dose- dependently but plasma half-lives remained constant regardless of GC-rhEPO doses. Following SC administration, the plasma concentration increased slowly with half-life of 9.2 hours and reached peak at 8 hours. Mean residence time and bioavailability were 18.2 hours and 44%, respectively. After single IV dose of 100 unit/kg, tissue GC-rhEPO level was higher in bone marrow and spleen, while the depletion rate was slower in liver and bone marrow, indicating the higher affinity of GC-rhEPO to bone marrow. Taken together, the experimental results indicate that GC-rhEPO contained the typical pharmacokinetic properties and the tissue distribution patterns inherent to human erythropoietin.

• YAKHAK HOEJI
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• v.15 no.2
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• pp.41-52
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• 1971

Cu(II) chelates of several sulfanilamide derivatives (Sulfa-Cu) were prepared and their effects on solubility, absorptivity in intestinal lumen, biding tendency with serum protein and erythrocytes, concentration in rabbit blood, and acetylation rate were studied in comparison with their free ligand forms. For solubility concerned, the partition coefficients of Sulfa-Cu are decreased as following order: Sulfadimethoxine Copper chelate (SDM-Cu), Sulfamethoxypyridazine Copper chelate (SD-Cu), Sulfamerazine Copper chelate (SM-Cu), Sulfaisoxazole Copper chelate (SIX-Cu). The partition coefficients of SDM-Cu and ST-Cu were much greater than those of ligands. this phenomenone acounts for the rapid absorption of SDM-Cu and ST-Cu in the rat small intestine (in situ). The Sulfa-Cu were absorbed at the intestinal lumen of a rat in the rate of first order and there was no difference between long acting sulfa drugs and their Cu0chelates in biological half lives. In binding experiments, sulfa-Cu binded with serum protein in lower ratio than their ligands except SIX-Cu. On other hand, acetylation rates of sulfa-Cu were higher than those of free sulfa drugs and the acetylation rate were higher than those of free sulfa drugs and powder. In a experiment on Sulfa-Cu concentration in rabbit blood, the half lives of SD-Cu, SIX-cu, ST-Cu, and SM-Cu were longer than those of their ligands. Above all, the half life of SD-Cu appeared to be approximately 3.5 times logner than that of corresponding ligand, SD. When absorption of sulfa drugs or sulfa-Cu at the small intestinal lumen of a rat and the concentration in rabbit blood after absorption were compared, it was found that there was not always conrrelated.

• The Korean Journal of Pesticide Science
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• v.9 no.3
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• pp.231-236
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• 2005

This study was conducted to determine the amounts of pesticide residues after treatment of criterion dose with 4 pesticides(tolclofos-m, folpet, procymidone, and triflumizole) under cultivated period and to compare the biological half-life of pesticides with 6 kinetic models(first, zero and second order kinetics, power function, elovich and parabolic model) and to establish proposed field tolerance using biological half-lives. Recovery of 4 pesticides form strawberry was ranged from 85.1 to 105.5%. For all of 4 pesticides, dissipation rate was over 73% at 5 days after application. Among 6 kinetic models, first order kinetic model (FO) was best fit to describe the relationship between residual pattern of pesticides and time. Therefore, half-lives were calculated by FO for establishing the field tolerance. These results showed that half-life should be calculated by comparative best fit kinetic model and field tolerance can help to prevent unacceptable agricultural products from marketing. It is good for both consumers and farmers having safe agricultural products and financial benefits, respectively.

• Korean Journal of Environmental Agriculture
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• v.31 no.1
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• pp.45-51
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• 2012

BACKGROUND: This study was carried out to establish pre-harvest residue limit of fungicides pyrimethanil and trifloxystrobin in persimmon, based on dissipation and biological half-lives of two fungicides residue. METHODS AND RESULTS: Both pyrimethanil and trifloxystrobin were extracted with acetonitrile, clean-up with $NH_2$ SPE cartridge and residue were analyzed by HPLC/DAD. Limit of Detection was 0.01 mg/kg. Average recovery were $81{\pm}1.62%$, $98{\pm}1.58%$ of pyrimethanil, and $91{\pm}2.94%$, $98{\pm}1.25%$ of trifloxystrobin at fortification levels at 0.1 and 0.5 mg/kg, respectively. CONCLUSION: The biological half-lives of pyrimethanil were 15.6 and 11.6 days at sprayed with recommended and double dosage, respectively. The biological half-lives of trifloxystrobin were 10.4 and 10.3 days at sprayed with recommended and double dosage, respectively. The pre-harvest residue limit of pyrimethanil and trifloxystrobin were recommended as 2.69 and 0.83 mg/kg for 10 days before harvest, respectively.

• Journal of Pharmaceutical Investigation
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• v.22 no.4
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• pp.281-287
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• 1992

Omeprazole (OMZ) is very unstable in acidic solution, which selectively inhibit the release of the gastric juice in the gastric mucosa, In order to stabilize (OMZ) in oral solid dosage form, the enteric-coated microcapsules and compression-coated OMZ tablets containing lysine or arginine as stabilizer were prepared and their dissolution and stability test were performed. The haif life of OMZ microcapsules containing arginine was 194 days at $30^{\circ}C$ and OMZ was completely released in 60 min. The half-lives of enteric coated and non-coated compression-coated OMZ tablets with lysine were 292 and 95 days at $30^{\circ}C$, respectively. The half-lives of enteric coated and non-coated compression-coated tablets with arginine were 1752 and 293 days at $30^{\circ}C$, respectively, and OMZ were released completely in 20 min in the 2nd fluid of K.P.VI. Consequently, the enteric-coated compression-coated OMZ tablets with arginine as stabilizer provided a good formulation for oral solid dosage form.

• Journal of Pharmaceutical Investigation
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• v.29 no.1
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• pp.47-53
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• 1999

Gastrodia elata (GE) is an oriental medicinal herb which has been used traditionally for the treatment of various brain diseases including convulsion and epilepsy. The purpose of this study was to determine pharmacokinetic parameters of 4-hydroxy-3-methoxybenzaldehyde (HMBA) and p-hydroxybenzaldehyde (PHBA), constituents of GE, in rats. Male rats were cannulated in the femoral vein, femoral artery, bile duct and ureter. They received a single i.v. bolus dose of either HMBA or PHBA through the femoral vein. The concentration of HMBA or PHBA in plasma, bile and urine samples were analyzed by reversed-phase HPLC. HMBA and PHBA have very short half-lives, i.e. 4.03 and 2.26 minutes respectively. Most of HMBA and PHBA were thought to be eliminated through metabolism as the metabolized fraction approaches unity. Derivatives of HMBA or PHBA with longer biological half-lives should be designed to develop better anticonvulsants and more complete qualitative and quantitative understanding of the overall pharmacokinetic fate of these compounds awaits further investigation.

• Proceedings of the Korean Society of Applied Pharmacology
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• 2001.11a
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• pp.88-88
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• 2001

The effects of pH and temperature on the degradation of prokidn in various buffered aqueous solutions(pH 1.32~9.66) and temperatures (35, 45 and 6$0^{\circ}C$ were investigated. The effect of ionic strength on the degradation of prokidin was also measured by varying ionic strength (0.0466~1.5) at pH 1.35 and 45$^{\circ}C$ The effect of metal ions on the degradation of prokidin at pH 7.35 and 3.98 was observed. The degradation of prokidin followed the pseudo- first- order kinetics. The degradation rate of prokidin showed pH-dependent and temperature-dependent patterns. Prokidin was very stable at the pH below 3.95, where half-lives at 35, 45 and 6$0^{\circ}C$were 294, 206 and 107 day, respectively. However, it degraded very rapidly at pH above 6.49; the half-lives at 35, 45 and 6$0^{\circ}C$were 60, 25 and 13 day, respectively. As ionic strength increased, the degradation rate of prokidin increased. Some metal ions increased the degradation rate in the rank order of Mn > Fe > Cu >Fe On the other hand. other metal ions such as Bi, Ba. Zn, Ni, Co did not show unfavorable effect.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.2 no.1
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• pp.266-295
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• 1974

The purpose of this study is to make a contribution to the effective management of medical literature in Korean libraries and specifically to help to select medical books and periodicals by determining the value and life of medical literature by means of citation counting and analysis. This report will present methods of calculation and data collection to measure the importance, half life of medical literature and the authority of author for Korean medical libraries. The writer conducted comparative studies based on data covering a two-year period, 1970-1971, using about 16,899 citations in 1,032 articles of the above journals. The references and citations are counted and analyzed by the number of authors, periodicals. books and publication dates. By the following ratio. calculated by the citation counting and analysis, we can decide the rates of medical periodicals to books, foreign literature to domestic literature and literature of the most numerously cited. authors, for the selecting method of Korean Medical libraries. (1) It is disclosed that 61 main authors are cited 9 times. Most of them are Western authors, they are cited 14,374 times which represents 88.6 % of the total citations. (2) The cited medical literature is classified as follows: The ratio of cited medical periodicals to the cited medical books is 82.0%. (The books at a rate of 18.0%.) Therefore, the wnter concentrated the efforts on the analysis of periodicals. (3) Classification of the periodicals by countries indicates that about 11.2% of total citations are made from Korean medical literature. The medical activities in Korea are dependent on the advanced foreign countries at ratio of 88.8%. Of the foreign medical periodicals cited, Japanese literature represents only 4.5% while literature of European countries and America constitutes 84.3%. (4) If medical journals are arranged in order of decreasing productivity of articles on a given subject, they may be revealed that it is necessary to have 98 titles of key journals to cover 60% of information in the field of medical science and 60 titles for an average of 50%. (5) For the purpose of measuring the life of medical literature in Korea, the writer has calculated the half lives of periodicals and books as follows: Kinds of Literature 1. Periodicals 2. Books 3. Whole literature Half-lives 7.75 years 4.11 years 6.37 years (6) The half lives of domestic and Japanese literature in the medical science are comparatively short.

• Korean Journal of Environmental Agriculture
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• v.36 no.1
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• pp.50-56
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• 2017

BACKGROUND: The present study was carried out to identify the residue patterns of insecticide pyridalyl and fungicide fluopicolide in watermelon and calculate the biological half-lives for establishing the pre-harvest residue limits (PHRLs). METHODSANDRESULTS:The watermelon samples for residue analysis were harvested 7 times during 0~10 days (Field 1) and 0~20 days (Field 2) after treatment of pesticides on watermelon in two different fields at the recommended dose, respectively. The residue analysis was conducted with HPLC/UVD. The method limit of quantitation (MLOQ) were set at 0.05 and 0.02 mg/kg, respectively, and overall mean recoveries were 81.2~90.5% for pyridalyl and fluopicolide. The residues in sample were stable for 43~47 days. The initial residue amount in field 1 and 2 were 0.12~0.16 mg/kg for pyridalyl and 0.23~0.24 mg/kg for fluopicolide, which were below maximum residue limit (MRL). The biological half-lives in field 1 and 2 were 26.9 and 17.9 days for pyridalyl and 16.6 and 94.2 days for fluopicolide, respectively. CONCLUSION: The PHRL for watermelon were estimated as 0.21 and 1.03 mg/kg for pyridalyl and flopicolide at 10 days before harvesting. The residue patterns of pyridalyl and fluopicolide were characterized by a very slow decrease of residue levels in watermelon.