• Biomedical Science Letters
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• v.11 no.3
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• pp.327-332
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• 2005

Sf21 cells become popular as the host permissive cell line to support the baculovirus AcNPV replication and protein synthesis. The cells grow well on TC-100 medium that contains $0.1\%$ D-glucose as the major carbon source, strongly suggesting the presence of endogenous glucose transporters. However, unlike human glucose transporters, very little is known about the characteristics of the endogenoussugar transporter(s) in Sf21 cells. Thus, some kinetic properties of the sugar transport system were investigated, involving the uptake of 2-deoxy-D-glucose (2dG1c). In order to obtain a true measure of the initial rate of uptake, the uptake of $[^3H]2dGlc$ from both low $(100{\mu}M)$ and high (10 mM) extracellular concentrations was measured over periods ranging from 30 sec to30 min. The data obtained indicated that the uptake was linear for at least 2 min at both concentrations, suggesting that measurements made over a 1min time course would reflect initial rates of the jexpse uptake. To determine $K_m\;and\;V_{max}$ of the endogenous glucose transporter(s) in Sf21 cells, the uptake of 2dG1c was measured over a range of substrate concentrations $(50{\mu}M\~10mM)$ 2dG1c uptake by the Sf21 cells appeared to involve both saturable and non-saturable (or very low affinity) components. A saturable transport system for 2dG1c was relatively high, the $K_m$ value for uptake being < 0.45 mM. The $V_{max}$ value obtained for 2dG1c transport in the Sf21 cells was about 9.7-folds higher than that reported for Chinese hamster ovary cells, which contain a GLUT1 homologue. Thus, it appeared that the transport activity of the Sf21 cells was very high. In addition, the Sf21 glucose transporter was found to have very low affinity for cytochalasin B, a potent inhibitor of human erythrocyte glucose transporter

• 한국생물공학회:학술대회논문집
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• 2000.04a
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• pp.161-164
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• 2000

In hybridoma cell culture, $NH_4{^+}$ is the most important toxic byproduct so far identified. It has been postulated that $NH_4{^+}$, which is similar to $K^+$ in size, is taken up non-specifically by the cells through a potassium transport system, and that the addition of $K^+$ to the culture medium may have a detoxifying effect of $NH_4{^+}$. Thus, in this article the effects of high $K^+$ concentrations in the range of 10 mM to 60mM on hybridoma cell growth and metabolism were investigated. No significant differences in growth were found for $K^+$ concentrations up to 40 mM, but cell death in the death phase was slightly delayed in the cultures with $K^+$ addition. At 60mM, growth was initially poor but the cells could be adapted after approximately 13 passages. With similar growth levels for high $K^+$ concentrations having been Identified in batch cultivations using basal medium, we are currently investigating how such high levels of $K^+$ will affect cell growth in fortified batch cultures where the accumulation of $NH_4{^+}$ is more problematical.

• Nuclear Engineering and Technology
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• v.49 no.7
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• pp.1489-1494
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• 2017

The use of a room-temperature gamma spectrometer is an issue in environmental radiation monitoring. To monitor radionuclides released around a nuclear power plant, suitable instruments giving fast and reliable information are required. High-pressure xenon (HPXe) chambers have range of resolution and efficiency equivalent to those of other medium resolution detectors such as those using NaI(Tl), CdZnTe, and $LaBr_3:Ce$. An HPXe chamber could be a cost-effective alternative, assuming temperature stability and reliability. The CEA LIST actively studied and developed HPXe-based technology applied for environmental monitoring. Xenon purification and conditioning was performed. The design of a 4-L HPXe detector was performed to minimize the detector capacitance and the required power supply. Simulations were done with the MCNPX2.7 particle transport code to estimate the intrinsic efficiency of the HPXe detector. A behavioral study dealing with ballistic deficits and electronic noise will be utilized to provide perspective for further analysis.

• Journal of the Korean Applied Science and Technology
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• v.15 no.4
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• pp.11-20
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• 1998

The propagation of light radiation in a turbid medium is an important problem that confronts dosimetry of therapeutic laser delivery and the development of diagnostic spectroscopy. Scattered light is measured as a function of the position(distance r, depth z) between the axis of the incident beam and the detection spot. Turbid sample yields a very forward-directed scattering pattern at short range of position from source to detector, whereas the thicker samples greatly attenuated the on-axis intensity at long range of position. The portions of scattered light reflected from or transmitted throughphantom depend upon internal reflectance and absorption properties of the phantom. Monte Carlo simulation method for modelling light transport in tissue is applied. It uses the photon is moved a distance where it may be scattered, absorbed, propagated, internally reflected, or transmitted out of tissue. The photon is repeatedly moved until it either escape from or is absorbed by the phantom. In order to obtain an optimum therapeutic ratio in phantom material, optimum control the light energy fluence rate is essential. This study is to discuss the physical mechanisms determining the actual light dose in phantom. Permitting a qualitative understanding of the measurements. It may also aid in designing the best model for laser medicine and application of medical engineering.

• Journal of Advanced Navigation Technology
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• v.13 no.6
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• pp.933-942
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• 2009

In this paper, the WAVE technology for IT based on Intelligent Transport System(ITS) which using by IEEE 802.11a PHY, IEEE 802.11p MAC(Medium Access Control) and IEEE P1609.3 was implemented. The WAVE system was designed that has maximum 0.5km communication range for RSU(Road Side Equipment) between vehicle, 12Mbps transfer speed when downlink at maximum 120km/h vehicle speed. To verify suitableness of the WAVE system for ITS, we measured several parameters on the real road: communication range when low and high speed, link establishment time, data transfer speed, PER (Percent Error Rate), and latency. From the experiment results, we demonstrated that WAVE is a suitable technology for IT based on ITS.

• The Korean Journal of Physiology and Pharmacology
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• v.3 no.5
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• pp.513-519
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• 1999

Direct exposure of renal tubular brush-border membranes (BBM) to free cadmium (Cd) causes a reduction in phosphate (Pi) transport capacity. Biochemical mechanism of this reduction was investigated in the present study. Renal proximal tubular brush-border membrane vesicles (BBMV) were isolated from rabbit kidney outer cortex by Mg precipitation method. Vesicles were exposed to $50{\sim}200\;{\mu}M\;CdCl_2$ for 30 min, then the phosphate transporter activity was determined. The range of Cd concentration employed in this study was comparable to that of the unbound Cd documented in renal cortical tissues of Cd-exposed animals at the time of onset of renal dysfunction. The rate of sodium-dependent phosphate transport $(Na^+-Pi\;cotransport)$ by BBMV was determined by $^{32}P-Iabeled$ inorganic phosphate uptake, and the number of $Na^+-Pi$ cotransporters in the BBM was assessed by Pi-protectable $^{14}C-labeled$ phosphonoformic acid $([^{14}C]PFA)$ binding. The exposure of BBMV to Cd decreased the $Na^+-Pi$ cotransport activity in proportion to the Cd concentration in the preincubation medium, but it showed no apparent effect on the Pi-protectable PFA binding. These results indicate that an interaction of renal BBM with free Cd induces a reduction in $Na^+-Pi$ cotransport activity without altering the carrier density in the membrane. This, in turn, suggest that the suppression of phosphate transport capacity $(V_{max})$ observed in Cd-treated renal BBM is due to a reduction in $Na^+-Pi$ translocation by existing carriers, possibly by Cd-induced fall in membrane fluidity.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.5
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• pp.775-781
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• 2002

The T-type amino acid transporter 1 (TATI) is a Na$^{+}$-independent amino acid transporter which selectively trans- ports aromatic amino acids subserving the amino acid transport system T. To understand the transport properties of aromatic amino acids by human TAT1 (hTATl ), we have examined the hTATl -mediated aromatic amino acid transports using a Xenopus laeuis oocyte expression system. When expressed in Xenopin laeuis oocytes, hTATl induced L- [$^{14}$ C]tryptophan transport which was not dependent on Na$^{+}$ or Cl$^{[-10]}$ in the medium. Uptake was time-dependent and exhibited a linear dependence on incubation time up to 30 min. The L- ($^{14}$ C)tryptophan uptake was highly inhibited by L-isomers of tryptophan, tyrosine and phenylalanine, whereas other L-amino acids did not inhibit hTATl -mediated L- ($^{14}$ C)tryptophan uptake. The hTATl induced the relatively low-affinity transport of aromatic amino acids such as L- ($^{14}$ C)tryptophan, L- ($^{14}$ C)tyrosine and L- ($^{14}$ C)phenylalanine (Km values: 450～750 $\mu$M), consistent with the properties of classical amino acid transport system T. The L- ($^{14}$ C)tryptophan uptake did not show any remarkable pH dependence within the pH range of 5.5 to 8.5. The time-dependent efflux of L- ($^{14}$ C)tryptophan was detected from the oocytes expressing hTATl, which was not affected by the presence or absence of L-tryptophan in the extracellular medium, indicating that hTATl-mediated transport is due to the facilitated diffusion. Expression of hTATl in Xenopu laevis oocytes induced the transport of tryptophan, tyrosine and phenylalanine, indicating that hTATl is a transporter subserving system T These results suggest that hTATl has essential roles in the absorption of aromatic amino acids from epithelial cells to the blood stream. Hecause hTATl is proposed to be crucial to the efficient absorption of aromatic amino acids from intestine and kidney, its defect such as blue diaper syndrome could be involved in the disruption of aromatic amino acid transport.ort.

• Journal of Embryo Transfer
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• v.25 no.4
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• pp.259-262
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• 2010

Optimization of the preimplantation mammalian embryo culture condition was widely focused on refining medium composition under the name of chemically defined media. However, recent research revealed that the alteration of physical environment can be a crucial factor to a successful embryo development. In this study, under the same embryo density, a novel culture device named oil-free micro tube culture (MTC) system was evaluated using porcine parthenogenetic embryos. The activated oocytes were placed into the 0.2 ml thin-wall flat cap PCR tube and cultured to the blastocyst stage. As a preliminary step, embryo density and culture medium volume were optimized under a standard drop culture system. The optimal embryo density range for in vitro culture was 0.5 embryos per ${\mu}l$ in $20\;{\mu}l$ drop (20.5%) and 1.0 embryos per ${\mu}l$ in $10\;{\mu}l$ drop (20.6%). Based on these results, we compared drop culture system and 'MTC' system in terms of the developmental rate to the blastocyst stage. In $20\;{\mu}l$ medium volume, the 'MTC' system showed similar blastocyst formation rate when compared with drop culture system (20.2% versus 20.5%, respectively) while the 'MTC' system showed lower blastocyst formation rate than drop culture system in $10\;{\mu}l$ one (12.7% versus 20.0%, respectively). Therefore the $20\;{\mu}l$ MTC system may be an alternative incubation system for short-distance embryo transport without carrying the $CO_2$ incubator and this provides novel embryo culture device to clinical veterinary embryologists.

• The Korean Journal of Physiology
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• v.17 no.2
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• pp.125-133
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• 1983

Red cell glycolytic intermediates, metabolites and metabolic ratios were studied. Glycolytic intermediates were measured in neutralized perchloric acid extracts of red cell suspensions after 3 hr incubation at $37^{\circ}C$ in the presence and absence of saponin. Adenosine triphosphate(ATP), adenosine diphosphate(ADP), pyruvate and lactate were measured by enzymatic procedures involving stoichiometric oxidation or reduction of a pyridine nucleotide. Glucose was determined using glucose oxidase after zinc hydroxide extraction. The redox state was calculated from the lactate dehydrogenase equilibrium. Adenosine triphosphatase activity(ATPase) was measured by determining the amount of phosphate released from ATP by washed erythrocyte membranes(ghost) during 20 min. incubation. Both total hydrolysis and the amount of hydrolysis that occured in the presence of ouabain were measured. The second measurement yields Mg-ATPase and represents nonspecific ATPase activity of the membranes. The difference between total and Mg-ATPase activity can be attributed to Na-K-ATPase. For the measurement of sodium fluxes, human erythrocytes were preincubated in $^{22}Na$ for 3 hr at $37^{\circ}C$, washed and suspended in a tracer-free medium. The amount of $^{22}Na$ transported out of cells at any time was determined by analysis of supernatant samples taken at various time after addition of the labeled cells to isotope-free medium. The cells and medium were separated and the radioactivity appearing in the medium was measured. From the total radioactivity in the suspension and the radioactivity appearing in the medium at known time, the rate constant for sodium release was computed. The results are summarized as follows: 1) ATP and ATP/ADP were found to increase at every concentration of saponin tested whereas ADP declined at every cone. of saponin. The increase in pyruvate and lactate were observed at every cone, of saponin and thus $NAD^+/NADH$ computed from pyruvate/lactate also increased. Glucose utilization was stimulated by saponin. 2) $Na^+-K^+-ATPase$ activities showed a biphasic response to saponin, first increasing in lower concentration and then decreasing in higher concentration of saponin. 3) The efflux of sodium was significantly increased by saponin in the range of 5 to 10 mg%. The stimulatory effect of saponin on the rate constants for active(ouabain-sensitive) sodium efflux was inhibited by addition of ouabain.

• Journal of Pharmaceutical Investigation
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• v.25 no.2
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• pp.137-143
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• 1995

The peptide transporter can be utilized for improving the bioavailability of compounds that are poorly absorbed. Characterization of the dipeptide uptake into the human intestinal epithelial cells, HT-29 was investigated. The uptake of tritiated glycylsarcosine $([^3H]-Gly-Sar,\;0.1\;{\mu}Ci/ml)$ was measured in confluent or subconfluent HT-29, Caco-2, and Cos-7 cells. Uptake medium was the Dulbecco's Modified Eagle's Media (DMEM) adjusted to pH 6.0. Both HT-29 and Caco-2 cells expressed the dipeptide transporter significantly (p<0.005) but Cos-7 did not. Certain portions of passive uptake were observed in all three cell lines. Uptake of Gly-Sar was largest at 7 days after plating HT-29 cells with significant inhibition with 25 mM cold Gly-Sar (p<0.05). but expression ratio of the dipeptide transporter was 0.7, suggesting lower expression. The effect of pH on Gly-Sar uptake was not significant in the range of pH 6 to 8. Gly-Sar uptake was also inhibited with 50 mM carnosine, 25 mM Gly-Sar, and 35 mM cephalexin significantly (p<0.05). From above results the dipeptide transporter was expressed well in HT-29 cells and was similar to that in the small intestine, suggesting that large amounts of mRNA of the transporter from the cells can be obtained.