• Current Optics and Photonics
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• v.3 no.1
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• pp.54-65
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• 2019

To develop a biomarker predicting tumor treatment efficacy is helpful to reduce time, medical expenditure, and efforts in oncology therapy. In clinics, microvessel density using immunohistochemistry has been proposed as an indicator that correlates with both tumor size and metastasis of cancer. In the preclinical study, we hypothesized that vascular morphometrics using optical coherence tomography angiography (OCTA) could be potential indicators to estimate the treatment efficacy of breast cancer. To verify this hypothesis, a 13762-MAT-B-III rat breast tumor was grown in a dorsal skinfold window chamber which was applied to a nude mouse, and the change in vascular morphology was longitudinally monitored during tumor growth and metronomic cyclophosphamide treatment. Based on the daily OCTA maximum intensity projection map, multiple vessel parameters (vessel skeleton density, vessel diameter index, fractal dimension, and lacunarity) were compared with the tumor size in no tumor, treated tumor, and untreated tumor cases. Although each case has only one animal, we found that the vessel skeleton density (VSD), vessel diameter index and fractal dimension (FD) tended to be positively correlated with tumor size while lacunarity showed a partially negative correlation. Moreover, we observed that the changes in the VSD and FD are prior to the morphological change of the tumor. This feasibility study would be helpful in evaluating the tumor vascular response to treatment in preclinical settings.

• Nuclear Engineering and Technology
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• v.55 no.11
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• pp.4167-4172
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• 2023

Miniaturized tissue equivalent proportional counters (mini-TEPCs) are proper for radiation dosimetry in medical application because the small size of the dosimeter could prevent pile-up effect under the high intensity of therapeutic beam. However, traditional methods of calibrating mini-TEPCs using internal alpha sources are not feasible due to their small size. In this study, we investigated the use of electron and proton edges on Monte Carlo-generated lineal energy spectra as markers for calibrating a 0.9 mm diameter and length mini-TEPC. Three possible markers for each spectrum were calculated and compared using different simulation tools. Our simulations showed that the electron edge markers were more consistent across different simulation tools than the proton edge markers, which showed greater variation due to differences in the microdosimetric spectra. In most cases, the second marker, y_δδ, had the smallest uncertainty. Our findings suggest that the lineal energy spectra from mini-TEPCs can be calibrated using Monte Carlo simulations that closely resemble real-world detector and source geometries.

• Animal Systematics, Evolution and Diversity
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• v.40 no.4
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• pp.294-301
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• 2024

The genus Notoplax is characterized by a fleshy girdle with shiny, hairy needles and a tegmentum of intermediate valves that extend greatly forward with a very narrow jugum. To date, 41 species of Notoplax have been recorded worldwide; however, relatively little is known about this genus in Korea, with only a single species. Notoplax kaasi previously reported. Here, we first report N. odysseyi Sirenko & Saito, 2017, which is the second Notoplax species from South Korea. N. odysseyi is a medium-sized chiton species distinguished from other congeneric species by a highly expanded, thick, hairy girdle, with inter-valve areas that are completely eroded. In addition, detailed microstructures of the shell and radula characters of N. odysseyi were described using scanning electron microscopy, providing valuable taxonomic information for the species identification of N. odysseyi. To confirm the species identification based on morphological data, we also performed a molecular phylogenetic analysis based on partial COI nucleotide sequences (550 bp) of 18 Acanthochitonidae. The resulting maximum-likelihood tree showed that N. odysseyi and N. conica formed a monophyletic group, which clustered with Leptoplax doederleini.

• Proceedings of the Materials Research Society of Korea Conference
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• 2007.11a
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• pp.156.1-156.1
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• 2007

• Polymer Science and Technology
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• v.25 no.5
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• pp.411-416
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• 2014

• Biomaterials and Biomechanics in Bioengineering
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• v.1 no.1
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• pp.27-39
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• 2014

We have previously described a new multilayer alginate microcapsule system, and the goals of the present study were to assess the in vitro function of islets encapsulated in its inner layer, and the angiogenic ability of FGF-1 delivered from the external layer in an omentum pouch. Following isolation and culture, islets were encapsulated in the inner core of microspheres ($500-600{\mu}m$ in diameter) with a semi-permeable poly-L-ornithine (PLO) membrane separating two alginate layers, and both unencapsulated and encapsulated islet function was assessed by a dynamic glucose perifusion. For angiogenesis experiments, one group of microcapsules without FGF-1 (control) and another (test) containing FGF-1 with heparin encapsulated in the external layer were made. One hundred microcapsules of each group were transplanted in Lewis rats (n = 5/group) and were retrieved after 14 days for assessment of angiogenesis. Glucose perifusion of unencapsulated and encapsulated islets resulted in similar stimulation indices. The release of FGF-1 resulted in increased vascular density compared to controls. In conclusion, islets encapsulated in the core of multilayer alginate microcapsules maintain functionality and the microcapsule's external layer is effective in delivery of FGF-1 to enhance graft neovascularization in a retrievable omentum pouch.

• Journal of Electrochemical Science and Technology
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• v.6 no.3
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• pp.106-110
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• 2015

This study investigates Cu(II) complexes of cyclam, propylene cross-bridged cyclam (PCB-cyclam), and propylene cross-bridged cyclam diacetate (PCB-TE2A) as homogeneous electrocatalysts for CO₂ reduction in comparison with Ni(II)-cyclam. It is found that Cu(II)-cyclam can catalyze CO₂ reduction at the potential close to its thermodynamic value (0.75 V vs. Ag/AgCl) in tris-HCl buffer (pH 8.45) on a glassy carbon electrode. Cu(II)-cyclam, however, suffers from severe demetalation due to the insufficient stability of Cu(I)-cyclam. Cu(II)-PCB-cyclam and Cu(II)-PCB-TE2A are revealed to exhibit much less demetalation behavior, but poor CO₂ reduction activities as well. The inferior electrocatalytic ability of Cu(II)-PCB-cyclam is ascribed to its redox potential that is too high for CO₂ reduction, and that of Cu(II)-PCB-TE2A to the steric hindrance preventing facile contact with CO₂ molecules. This study suggests that in addition to the redox potential and chemical stability, the stereochemical aspect has to be considered in designing efficient electrocatalysts for CO₂ reduction.

• International Journal of Vascular Biomedical Engineering
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• v.3 no.2
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• pp.1-9
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• 2005

Flow-induced dilation of blood vessel is the result of a series of bioreaction in vascular endothelial cells(VEC). Shear stress change by blood flow in human artery or vein is sensed by the mechanoreceptor and responsible for such a chain reaction. The inositol(1,4,5)-triphophate($IP_3$) is produced in the first stage to elevate permeability of the intercellular membrane to calcium ions by which the cytosolic calcium concentration is consequently increased. This intracellular calcium transient triggers synthesis of EDRF and prostacyclin. The mathematical model of this VEC calcium dynamics is reproduced from the literature. We then use the Computational Fluid Dynamics(CFD) technique to investigate the blood stream dictating the VEC calcium dynamics. The pulsatile blood flow in a stenosed blood vessel is considered here as a part of study on thrombogenesis. We calculate the pulsating shear stress (thus its temporal change) distributed over the stenosed artery that is implemented to the VEC calcium dynamics model. It has been found that the pulsatile shear stress induces larger intracellular $Ca^{2+}$ transient plus much higher amount of EDRF and prostacyclin release in comparison with the steady shear stress case. It is concluded that pulsatility of the physiological shear stress is important to keep the vasodilation function in the stenosed part of the blood vessel.

• Journal of Microbiology and Biotechnology
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• v.20 no.6
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• pp.959-967
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• 2010

Down syndrome (DS) is an abnormality of the 21st chromosome that commonly occurs in children born to older women. Thus, amniotic fluid (AF) is usually collected from such women for prenatal diagnosis. This study analyzed human AF supernatants (AFS) using a mass spectrometric (MS) approach to search for candidate biomarkers of a DS pregnancy. The AFS were collected from older pregnant women at weeks 16-18 of their gestation by amniocentesis for cytogenetic analysis. The AFS from the pregnancies carrying DS (n=4) or chromosomally normal (n=6) fetuses, as revealed by the cytogenetic analysis, were then subjected to global protein profiling based on liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS). Affinity chromatography was also applied prior to the LC-ESI-MS/MS to minimize the masking effect of highly abundant albumin and immunoglobulin and thereby increase the diversity of the identified proteins. As a result, at least 30 new AFS proteins were identified and 44 AFS proteins were found to be differentially expressed between the DS and normal cases, where 6 of the proteins were unique to the DS cases and 11 were unique to the chromosomally normal cases. In addition, in the DS cases, 19 AFS proteins were downregulated and 8 were upregulated to varying degrees. A Western blot analysis confirmed the LC-ESI-MS/MS data, indicating that the combined detection of apolipoprotein A-II (apoA-II) and alpha-fetoprotein (AFP) could be a potential tool for diagnosing DS cases.

• Journal of Biomedical Engineering Research
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• v.38 no.6
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• pp.302-307
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• 2017

This paper presents a paper-based concentration gradient chip to analyze colorimetric glucose assay. The paper-based concentration gradient chip was fabricated through a wax patterning technique that can design the fluidic channel by selectively printing hydrophobic and hydrophilic areas. Afterwards, glucose and dilution solutions were loaded into the inlet of a concentration gradient chip and each solution was then mixed sequentially at mixing channel. Finally, concentration gradient was formed at each outlet of the chip. To measure the glucose concentration of the solution in outlets, we conducted colorimetric glucose assay with fixed concentration of glucose solution (0, 5, 10, 15 and 20 mM) and obtained normalized intensity. Subsequently, glucose concentrations of the outlets were calculated by substituting the normalized intensity to linear regression function based on the normalized intensity of fixed glucose concentration. Finally, the concentration gradient of glucose was formed on the chip with the result of colorimetric assay. The concentration gradient paper chip has the potential to accurately analyze unknown glucose concentration.