• Korean Journal of Veterinary Research
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• v.23 no.1
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• pp.1-8
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• 1983

The purpose of the present study is to determine variations in synthesis of DNA in the nuclei of various elements of the golden hamster (Mesocricetus auratus) placenta with increasing gestational age from the eighth day post coitus to parturition. The method employed for such determination was autoradiography following injection of pregnant animals with tritiated thymidine. From the results reported, the following points are concluded. The mitotic activities of the endodermal cells of the visceral yolk sac and of the parietal yolk sac, the trophoblastic cells of the labyrinth and the trophospongium and the giant cells were decreased with increasing gestational age, The placentation was nearly completed by day 13 of pregnancy and the increase in size of labyrinth was by appositional growth from the trophospongial cells. It was considered that the inner trophoblastic cells in the vicinity of the fetal blood vessels were originated from the pure chorion. The interrelation among the various cells and the polyploidal giant cells in the placenta were discussed.

• Environmental Analysis Health and Toxicology
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• v.18 no.2
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• pp.111-120
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• 2003

The validation of many synthetic chemicals that may pose a genetic hazard in our environment is of great concern at present. Since these substances are not limited to the original products, and enter the environment, they have become widespread environmental pollutants, thus leading to a variety of chemicals that possibly threaten the public health. In this respect, the regulation and evaluation of the chemical hazard playa very important role to environment and human health. The clastogenicity of 17 synthetic chemicals was evaluated in Chinese hamster lung fibroblast cells in vitro. 2-Nitroaniline (CAS No. 88-74-4) induced chromosomal aberrations with statistical significance at the concentration of 86.3 ${\mu}$g/ml in the absence of metabolic activation system. 1-Chloroanthraquinone (CAS No. 82-44-0) which is one of the most cytotoxic chemical among 17 chemicals tested revealed no clastogenicity in the range of 0.8 ∼ 3.0 ${\mu}$g/ml both in the presence and absence of S-9 metabolic activation system. From the results of chromosomal aberration assay with 17 synthetic chemicals in Chinese hamster lung cells in vitro, 2-Nitroaniline (CAS No. 88-74-4) revealed weak positive clastogenic results in this study.

• The Korean Journal of Physiology
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• v.28 no.2
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• pp.215-224
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• 1994

The presence of a calcium current $(i_{Ca^{2+}})$ passed via a specific channel was examined in the unfertilized hamster egg using the whole-cell voltage clamp technique. Pure inward current was isolated using a $Ca^{2+}-rich$ pipette solution containing 10 mM TEA. This current was independent of external $Na^+$ and was highly sensitive to the $Ca^{2+}$ concentration in the bathing solution, indicating that the inward current is carried by $Ca^{2+}$. The maximal amplitude was $-4.12{\pm}0.58nA\;(n=12)$ with 10mM $Ca^{2+}$ at -3OmV from a holding potential of -8OmV. This current reached its maximum within 20ms beyond -3OmV and decayed rapidly with an inactivation time constant $({\tau})$ of 15ms. Activation and inactivation of this $i_{Ca^{2+}}$ was steeply dependent on the membrane potential. The $i_{Ca^{2+}}$ began to activate at the lower voltage of -55 mV and reached its peak at -35 mV, being completely inactivated at potentials more positive than -40 mV. These result suggest that $i_{Ca^{2+}}$ in hamster eggs passes through channels with electrical properties similar to low voltage-activated T-type channels. Other results from the present study support this suggestion; First, the inhibitory effect of $Ni^{2+}\;(IC_{50}=13.7\;{\mu}M)$ was more potent than $Cd^{2+}\;(IC_{50}=123\;{\mu}M)$. Second, $Ba^{2+}$ conductance was equal to or below that of $Ca^{2+}$. Third, $i_{Ca^{2+}}$ in hamster eggs was relatively insensitive to nifedipine $(IC_{50}=96.6\;{\mu}M)$, known to be a specific t-type blocker. The physiological role of $i_{Ca^{2+}}$ in the unfertilized hamster eggs remains unclear. Analysis from steady-state inactivation activation curves reveals that only a small amount of this current will pass in the voltage range $(-70{\sim}-30\;mV)$ which partially overlaps with the resting membrane potential. This current has the property that it can be easily activated by a weak depolarization, thus it may trigger a certain kind of a intracellular event following fertilization which may cause oscillations in the membrane potential.

• Korean Journal of Animal Reproduction
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• v.23 no.1
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• pp.29-36
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• 1999

This study were performed the effect of methylxanthine derivatives on hamster epididymal sperm motility. To assess the effect of methylxanthine derivatives on motility kinematics of epididymal sperm, pentoxifylline, 2-deoxy-adenosine and hypoxanthine were added to TALP medium. 1 mM of pentoxifylline, significantly increased VCL, VAP, VSL of spermatozoa obtained from corpus and cauda epididymis. With 1 mM of 2-deoxyadenosine, VCL, VAP, VSL of spermatozoa obtained from corpus and cauda epididymis were significantly increased, but 2 mM ADE for cauda spermatozoa was effective than 1 mM. In the case of hypoxanthine, various concentrations were not significantly effective, but 2 mM HX showed higher effect than other concentrations. pentoxifylline 1 mM and 2-deoxyadenosine 1 mM significantly increased VCL, VAP of corpus and cauda epididymal spermatozoa and VSL of cauda epididymal spermatozoa. From these results it could be concluded that the addition of methylxanthine increase motility kinematics of hamster spermatozoa collected from epididymis.

• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.153-158
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• 2003

The genome-wide program of gene expression during the cell division cycle response to serum free media in chinese hamster ovary(CHO) cells was characterized using cDNA microarrays. Many transcripts of genes showed variation during the cell cycle. Characterization is critical step toward understanding the basic cell cycle processes and serum-free media role in CHO cells

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.231.2-231.2
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• 2003

The efficient EPO (Erythropoietin) expression system in Chinese Hamster Ovary (CHO) cells was devised through the removal of ammonium ion accumulated in the media by introducing urea cycle enzymes. Previously, we developed C05 cell by transfecting the carbamoly phosphate synthase (CPS) and ornithine transcarbamoylase (OTC) into the EPO expressing CHO cell, IBE. (omitted)

• Journal of Nutrition and Health
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• v.36 no.1
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• pp.24-31
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• 2003

The present study was attempted to investigate the antioxidant capacity of popular yellow-green vegetable juices (kale, Angelica keishei, carrot, small water dropwort) and to investigate the effect of vegetable juices on protecting oxidative damage to DNA in cultured Chinese hamster lung (CHL) cells. Antioxidant capacity was analyzed by TRAP assay (Total radical-trapping antioxidant potential). Cellular DNA dmamage was measured by SCGE (single-cell gel electrophoresis, also known as comet assay. Cells incubated in medium with PBS (negative control) or with various concentration of the freeze dried green juices (25, 50, 100, 250 $\mu\textrm{g}$/$m\ell$) resuspended in PBS were treated with $H_2O_2$ (200 ${\mu}{\textrm}{m}$) as an oxidative stimulus for 5 min at 4$^{\circ}C$. The physiological function of each vegetable juice on oxidative DNA damage was analyzed and expressed as tail moment (tail length X percentage migrated DNA in tail) . Kale juice had the highest TRAP value suggesting that kale has the highest antioxidant capacity followed by Angelica keishei, small water dropwort and carrot. Cells treated with $H_2O_2$ had extensive DNA damage compared with cells treated with PBS or pre-treated with vegetable juice extracts. All green juices inhibited $H_2O_2$-induced DNA damage with kale being the most effective juice among the tested juices. These results indicate that green juice supplementation to CHL cells followed by oxidative stimulus inhibited damage to cellular DNA, supporting a protective effect against oxidative damage induced by reactive oxygen species. (Korean J Nutrition 36(1) : 24-31, 2003)

• Environmental Mutagens and Carcinogens
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• v.21 no.1
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• pp.14-22
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• 2001

The detection of many synthetic chemicals used in industry that may pose a genetic hazard in our environment is of great concern at present. In this respect, administrative authorities has great concern to regulate and to evaluate the chemical hazard to environment and human health. The clastogenicity of 28 synthetic chemicals was evaluated in Chinese hamster lung fibroblast cells in vitro. Glycidylacrylate which is one of the most cytotoxic chemical among 28 chemicals tested revealed clastogenicity in the range of 0.31-1.25 $\mu\textrm{g}$/$m\ell$ both in the presence and absence of metabolic activation system. Neopentyl glycol (340-1360 $\mu\textrm{g}$/$m\ell$) also revealed weak positive result both in the presence and absence of metabolic activation system. Cyanoguanidine (/$420.5-841 $\mu\textrm{g}$m\ell$) and N-butylchloride ($231.5-926 $\mu\textrm{g}$/m\ell$) revealed weak positive result only in the absence of S-9 metabolic activation system. Nevertheless total aberration percentages of N-butylchloride in the presence of metabolic activation system, and 3,4＇-dichlorobenztrifluoride in the absence of S-9 metabolic activation revealed above 5% aberration, there is no statistical significance. From the results of chromosomal aberration assay with 28 synthetic chemicals in Chinese hamster lung cells, glycidylacrylate (CAS No. 106-90-0), neopentyl glycol (CAS No. 126-30-7), N-butyl chloride (CAS No. 109-69-3) and cyanoguanidine (CAS No. 461-58-5) revealed positive clastogenic results in this study.

• Environmental Mutagens and Carcinogens
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• v.22 no.4
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• pp.215-222
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• 2002

The detection of many synthetic chemicals used in industry that may pose a genetic hazard in our environment is of great concern at present. Since these substances are not limited to the original products, and enter the environment, they have become widespread environmental pollutants, thus leading to a variety of chemicals that possibly threaten the public health. In this respect, to regulate and to evaluate the chemical hazard will be important to environment and human health. The clastogenicity of 17 synthetic chemicals was evaluated in Chinese hamster lung fibroblast cells in vitro. Two most cytotoxic chemicals, dodecyl methacrylate (CAS No. 142-90-5) and 2-ethylhexyl methacrylate (CAS No. 688-84-6), among 17 chemicals tested revealed no clastogenicity in the range of 0.0165-0.066 $\mu\textrm{g}$/$m\ell$ and 0.006-0.024 $\mu\textrm{g}$/$m\ell$ both in the presence and absence of metabolic activation system, respectively. All 17 chemicals revealed no significant induction of chromosomal aberration both in the presence and absence of metabolic activation system in this assay. From the results of chromosomal aberration assay with 17 synthetic chemicals in Chinese hamster lung cells in vitro, we did not observed positive clastogenic results in this study.

• The Korean Journal of Physiology and Pharmacology
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• v.4 no.5
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• pp.403-408
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• 2000

The outward currents elicited in hamster eggs by depolarizing pulses were studied. The currents appeared to comprise at least two components, a transient outward component $(I_{to})$ and a steady-state outward component $(I_{\infty}).\;I_{to}$ was transiently followed by the cessation of inward $Ca^{2+}$ current $(I_{Ca}),$ and its current-voltage (I-V) relation was a mirror image of that of $(I_{Ca}).$ Either blockade of $(I_{Ca})$ by $Co^{2+}$ or replacement of $Ca^{2+}$ with $Sr^{2+}$ abolished $I_{to}$ without change in $I_{\infty}.$ Intracellular EGTA (10 mM) inhibited $I_{to}$ but not $I_{\infty}.$ suggesting strongly that generation of $I_{to}$ requires intracellular $Ca^{2+}.$ Apamin (1 nM) abolished selectively $I_{to},$ indicatingthat $I_{to}$ is $Ca^{2+}-dependent\;K^+$ current. On the other hand, $I_{\infty}$ was $Ca^{2+}-independent.$ Both $I_{to}$ and $I_{\infty}$ were completely inhibited by internal $Cs^+$ and external TEA. The estimated reversal potential of $I_{to}$ was close to the theoretical $E_K.$ Taken together, both outward currents were carried by $K^+$ channels. From these results, $I_{to}$ is likely to be a current responsible for the hyperpolarizing responses seen in hamster eggs at fertilization.