Ji-Suk Park

Terahertz dynamic imaging of skin drug absorption

Terahertz (THz) imaging is a nondestructive, label-free, rapid imaging technique which gives the possibility of a real-time tracing of drugs within the skin. We evaluated the feasibility of THz dynamic imaging for visualizing serial changes in the distribution and penetration of a topical agent, dimethyl sulfoxide (DMSO) containing ketoprofen, using excised mouse skins. THz imaging was performed for 6 h after drug application to the skin and was compared with the results obtained using the Franz cell diffusion test, a standard in vitro skin absorption test. THz dynamic reflection imaging showed that the reflection signals decreased rapidly during the early time period, and remained constant through the late time period. The area of drug permeation within the skin layer on THz imaging increased with time. The dynamic pattern of THz reflection signal decrease was similar to that of DMSO absorption analyzed by the Franz cell diffusion test, which indicates that THz imaging mainly reflects the DMSO component. This study demonstrates that THz imaging technique can be used for imaging the spatial distribution and penetration of drug-applied sites.

Terahertz Tomographic Imaging of Transdermal Drug Delivery

In vivo imaging methods to trace topical drugs within the skin are in high demand with recent advances in transdermal drug delivery technology. With imaging and chemical identification capabilities, terahertz (THz) spectroscopy can be a good modality for visualizing and quantifying transdermal drug delivery. In this study, we evaluated the feasibility of THz reflection tomographic imaging for visualizing the distribution and penetration of a topical agent, ketoprofen dissolved in DMSO, using ex vivo and in vivo mouse skins. THz reflection imaging of ex vivo and in vivo skins demonstrated greater contrast between the drug-applied sites and unapplied skin than that of visual images. The reflectance signal of drug-applied sites was determined by mixed THz response of skin tissue, diffused ketoprofen, and DMSO content. Interestingly, serial B-scan images revealed that a new dark layer appeared at the drug-applied sites 1 h after drug application, which might be related with permeated ketoprofen. This study demonstrates that THz imaging technique can be utilized for imaging the distribution of topically applied drugs.

Variation Patterns in Concentration of Inorganic Nitrogen from Liquid Grass Fertilizer during Aerobic Incubation

To assess fertilizer value of an quasi-aerobically fermented liquid clipped-grass fertilizer, aerobic incubation experiment using two texturally contrasting loam (L) and sandy loam (SL) soils was conducted for 60 days to investigate temporal variations in N mineralization pattern of the liquid fertilizer applied. To do so, the quasi-aerobically fermented liquid clipped-grass fertilizer was prepared, applied to each soil at a rate of 200 kg-N and aerobically in the dark. During incubation, soil water content was adjusted to field moisture capacity (-33 kPa of soil matric potential) by adding distilled water as necessary to maintain their initial weights. At desired time of incubation (0, 1, 5, 10, 20, 40, and 60 days after incubation), soil was sampled and analyzed for inorganic nitrogen (-N and -N) concentrations, pH, EC, total carbon contents and total nitrogen contents. Concentrations of -N began to decrease right after incubation for L soils, and 10 days after incubation for SL soils, while those of -N began to increase onset of -N disappearance. The results of this study showed that quasi-aerobically fermented liquid clipped-grass fertilizer could serve as an alternative to chemical N fertilizer.

Nitrogen removal through N cycling from sediments in a constructed coastal marsh as assessed by 15 N–isotope dilution

Constructed coastal marsh regulates land-born nitrogen (N) loadings through salinity-dependent microbial N transformation processes. A hypothesis that salinity predominantly controls N removal in marsh was tested through incubation in a closed system with added-15NH4+ using sediments collected from five sub-marshes in Shihwa marsh, Korea. Time-course patterns of concentrations and 15N-atom% of soil-N pools were analyzed. Sediments having higher salinity and lower soil organic-C and acid-extractable organic-N exhibited slower rates of N mineralization and immobilization, nitrification, and denitrification. Rates of denitrification were not predicted well by sediment salinity but by its organic-C, indicating heterotrophic denitrification. Denitrification dominated N-loss from this marsh, and nitrogen removal capacity of this marsh was estimated at 337 kg N day-1 (9.9% of the daily N-loadings) considering the current rooting depth of common reeds (1.0 m). We showed that sediment N removal decreases with increasing salinity and can increase with increasing organic-C for heterotrophic denitrification.

Terahertz tomographic imaging of topical drugs

THz technology can be good modality for studying transdermal drug delivery due to their chemical identification and imaging capabilities. We demonstrate THz reflection and tomographic imaging to visualize the distribution of topically applied drugs.

A comparative study of older adult learning in Korea and Japan: Focusing on learning after 70 years old

ABSTRACT This study compares older adult learning in Korean and Japanese sample populations, paying special attention to learning after age 70. Surveys with nearly identical questionnaires were conducted in the Bundang Senior Welfare Center in Korea (N = 549, mean age 73.6 years) and at Osaka Prefecture Senior College in Japan (N = 1,491, 787, mean age = 67.4, 69.5 years). The main results are as follows: (a) in terms of learning needs, selected ratios of topics of “life review” and “communication with other seniors” increased as respondents increased in age from their 60s to 70s in both countries; (b) attitudes toward learning and social activities changed from “Novelty” to “Continuity” to “Disengagement” as respondents increased in age in both countries; and (c) the threshold age to old age was identified at around 75 years, not 70 years, particularly in Korean data. These results suggest that old age is a diverse period, and that creating ways to facilitate learning after age 70 is an urgent issue in the field of educational gerontology.

Effect of Mixed Liquid Fertilization on Growth Responses of Red peppers and Soil Chemical Properties

We evaluated the effect of mixed liquid fertilizer (MLF) on growth responses of plants and soil chemical properties. A pot experiment with red pepper (Capsicum annuum L.) using loam soil was conducted for 81 days in a temperature-controlled glasshouse, and four N fertilization treatments were laid out in a completely randomized design with three replicates: control (C), chemical fertilizer treatment (CF), and two rates (MLF-0.5 and MLF-1.0) of MLF treatment. Soils were periodically sampled and analyzed for pH, EC(Electrical Conductivity), total N, inorganic N and total C, and some growth characteristics of red peppers were measured. During the experimental periods, the pH of MLF soils was higher than that of CF soils. Soil EC increased right after application of CF or MLF, and the intial increase persisted in CF and MLF soils at the end of experiment. Soil total-N increased right after application of CF or MLF, and this initial increase persisted only in MLF-1.0 soils. Soil inorganic N content initially increased in CF or MLF-1.0 soils, but the initial increase disappeared in 56 days after transplanting. Soil total-C was maintained higher in MLF-1.0 soils and lower in CF soils than in control soils, and the intial increase in MLF-1.0 soils finally disappeared to the level of control soils. Plant height, dry weight of plant organs (shoots, roots and fruit), and the number, diameter and length of red pepper fruits were greatest in CF plants. On the other hand, the effect of MLF-application was different depending on the rate of application. However, no consistent effect of N treatments on some major elements of the organs of red peppers was observed. The amounts of N taken up by plants were 1.3 g for CF, 0.8 g for MLF-1.0, 0.5 g for MLF-0.5 and 0.4 g for control treatments. The results of this study showed that mixed liquid fertilizer (MLF) could appropriately serve as an alternative to chemical N fertilizer in red pepper cultivation.

Imaging and quantification of fatty liver by terahertz wave

Recently, quantifying the progress of fatty liver disease has been recognized as an important practice in medical science. Such quantification is performed to enable the treatment and diagnosis of fatty liver disease.

Erratum to: Vascular disrupting effect of CKD-516: preclinical study using DCE-MRI

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