• Proceedings of the Korean Society of Medical Physics Conference
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• 2006.08a
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• pp.124-124
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• 2006

• Nuclear Engineering and Technology
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• v.55 no.1
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• pp.248-253
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• 2023

Directly, it is not possible to measure the absorbed dose of radiopharmaceuticals in the organs of the human body. Therefore, simulation methods are utilized to estimate the dose in distinct organs. In this study, individual organs were separately considered as the source organ or target organ to calculate the mean absorption dose, which SAF and S factors were then calculated according to the target uptake via MIRD method. Here, ^99mTc activity distribution within the target was analyzed using the definition and simulation of ideal organs by summing the fraction of cumulative activities of the heart as source organ. Thus, GATE code was utilized to simulate the Zubal humanoid phantom. To validate the outcomes in comparison to the similar results reported, the accumulation of activity in the main organs of the body was calculated at the moment of injection and cardiac rest condition after 60 min of injection. The results showed the highest dose absorbed into pancreas was about 21%, then gallbladder 18%, kidney 16%, spleen 15%, heart 8%, liver 8%, thyroid 7%, lungs 5% and brain 2%, respectively, after 1 h of injection. This distinct simulation model may also be used for different periods after injection and modifying the prescribed dose.

• Proceedings of the Korean Nuclear Society Conference
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• 2004.10a
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• pp.1186-1187
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• 2004

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.232.2-232.2
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• 2002

Corticosteroids have been used most frequently for inflammatory bowel disease. They are well absorbed and only a limited fraction of the dose is delivered to the inflammatory site in the colon. To reduce side effects by the systemic absorption. colon-specific delivery is highly desirable. We designed dexamethasone 21-sulfate sodium (DS) as a cOlon-specific prodrug of dexamethasone (D) expecting that it might be stable and non absorbable in the upper intestine and dissociate in the colon by the sulfatase, an enzyme solely found in the colon. (omitted)

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.357.2-357.2
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• 2002

Corticosteroids have been used most frequently for inflammatory bowel disease.They are well absorbed and only a limited fraction of the dose is delivered to the inflammatory site in the colon. To reduce side effects by the systemic absorption. cOlon-specific delivery is highly desirable. We prepared prednisolone 21-sulfate sodium (PDS) and investigated its suitability as a colon-specific prodrug of prednisolone(PD). (omitted)

• Nuclear Engineering and Technology
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• v.55 no.12
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• pp.4659-4663
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• 2023

The use of iodine S values derived using the International Commission Radiological Protection (ICRP) phantoms may introduce significant bias in internal dosimetry for Koreans due to anatomical variability. In the current study, we produced an extensive dataset of Korean S values for selected five iodine radioisotopes (I-125, I-129, I131, I-133, and I-134) for use in radiation protection. To calculate S values, we implemented Monte Carlo simulations using the Mesh-type Reference Korean Phantoms (MRKPs), developed in a high-quality/fidelity mesh format. Noticeable differences were observed in S value comparisons between the Korean and ICRP reference phantoms with ratios (Korean/ICRP) widely ranging from 0.16 to 6.2. The majority of S value ratios were lower than the unity in Korean phantoms (interquartile range = 0.47-1.28; mean = 0.96; median = 0.69). The S values provided in the current study will be extensively utilized in iodine internal dosimetry for Koreans.

• Archives of Pharmacal Research
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• v.26 no.4
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• pp.264-269
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• 2003

5-Aminosalicylic acid (5-ASA) is an active ingredient of therapeutic agents used for Crohn s disease and ulcerative colitis. Because it is absorbed rapidly and extensively in the upper intestine, delivery of the agent specifically to the colon is necessary. We selected taurine as a colon-specific promoiety and designed 5-aminosalicyltaurine (5-ASA-Tau) as a new colon-specific prodrug of 5-aminosalicylic acid (5-ASA). It was expected that introduction of taurine would restrict the absorption of the prodrug and show additive effect to the anti-inflammatory action of 5-ASA after hydrolysis. 5-ASA-Tau was prepared in good yield by a simple synthetic route. The apparent partition coefficient of 5-ASA-Tau in 1-octanol/pH 6.8 phosphate buffer or $CHCl_3$/pH 6.8 phosphate buffer was 0.10 or 0.18, respectively, at $37^{\circ}C$. To determine the chemical and biochemical stability in the upper intestinal environment, 5-ASA-Tau was incubated in pH 1.2 and 6.8 buffer solutions, and with the homogenates of tissue and contents of stomach or small intestine of rats at $37^{\circ}C$. 5-ASA was not detected from any of the incubation medium with no change in the concentration of 5-ASA-Tau. On incubation of 5-ASA-Tau with the cecal and colonic contents of rats, the fraction of the dose released as 5-ASA was 45% and 20%, respectively, in 8 h. Considering low partition coefficient and stability in the upper intestine, 5-ASA-Tau might be nonabsorbable and stable in the upper intestine. After oral administration, it would be delivered to the colon in intact form and release 5-ASA and taurine. These results suggested 5-ASA-Tau as a promising colon-specific prodrug of 5-ASA.

• Journal of Ginseng Research
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• v.10 no.1
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• pp.108-113
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• 1986

Ginseng saponin absorbed in rat blood and liver were analyzed by High Performance Liquid Chromatography. The amount of saponin was estimated from peak area of the corresponding fraction and the specific radioactivity was then calculated, The radioactivity of the methanol-water extract of blood serum and livers of ginseng saponin administered rats decreased rapidly during the first four hours after the saponin administration. However, the radioactivity disappearance rate was relatively slow when the radioactivity was below a certain level. It seemed that the glycosides of panax ginseng were absorbed partly in the undissociated form and the saponin level of the liver might be maintained at 10-6% - 10-5% for a considerable period of time in ginseng administered rats.

• Journal of Radiation Protection and Research
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• v.48 no.1
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• pp.44-51
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• 2023

Background: Aptamers are currently being used in various fields including medical treatments due to their characteristics of selectively binding to specific molecules. Due to their special characteristics, the aptamers are expected to be used to remove radionuclides from a large amount of liquid radioactive waste generated during the decommissioning of nuclear power plants. The radiological effects on the aptamers should be evaluated to ensure their integrity for the application of a radionuclide removal technique. Materials and Methods: In this study, Monte Carlo N-Particle transport code version 6 (MCNP6) and Monte Carlo damage simulation (MCDS) codes were employed to evaluate the radiological effects on the aptamers. MCNP6 was used to evaluate the secondary electron spectrum and the absorbed dose in a medium. MCDS was used to calculate the DNA damage by using the secondary electron spectrum and the absorbed dose. Binding experiments were conducted to indirectly verify the results derived by MCNP6 and MCDS calculations. Results and Discussion: Damage yields of about 5.00×10^-4 were calculated for 100 bp aptamer due to the radiation dose of 1 Gy. In experiments with radioactive materials, the results that the removal rate of the radioactive ⁶⁰Co by the aptamer is the same with the non-radioactive ⁵⁹Co prove the accuracy of the previous DNA damage calculation. Conclusion: The evaluation results suggest that only very small fraction of significant number of the aptamers will be damaged by the radioactive materials in the liquid radioactive waste.

• Korean Journal of Veterinary Research
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• v.5 no.1
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• pp.43-57
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• 1965

It has been-reported that rabbit serum exhibit an inhibitory action on avian infectious bronchitis virus in embryonating chicken embryo. In this thesis, the biological, serological, physical and chemical properties of normal rabbit serum on the effect of the virus propagation were studied. Throughout the studies, the following experimental results 'were obtained and summarized here. 1. An inhibitory action of rabbit serum on avian infectious bronchitis vrius is due to the normal serum constituents. 2. The nature of the neutralization between normal rabbit serum and the virus is similar to that of the specific antiserum and the virus. 3. Rabbit serum, heat inactivated at $56^{\circ}C$, for 30 minutes, showed its average $log_{10}El,D_{50}Nl$ of 3.7. 4. The inhibitory compound present in the normal rabbit serum is inactivated by means of 5 per cent trypsin, 0.01 M potassium periodate, and absorbed to zymosan. 5. The inhibitory compound was not affected by 0.05 M trichloroacetic acid and 0.005M $KH_2PO_4$. 6. The higher the temperature of heat inactivation of rabbit serum caused the lesser the neutralizing effect on the virus. Heating the serum at $66^{\circ}C$, for 30 minutes brought about a complete loss of the neutralizing index of the serum. 7. No ions, as a cofactor, was incorporated to the inhibitory action of rabbit serum on the virus. 8. The inhibitory compound amays be found in a fraction of serum globulin.