• 대한치과교정학회지
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• 제45권4호
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• pp.198-208
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• 2015

Objective: To quantify, for each activation, the effect of preactivations of differing distribution and intensity on the neutral position of T-loops (7-mm height), specifically the horizontal force, moment to force (M/F) ratio, and load to deflection ratio. Methods: A total 100 loops measuring $0.017{\times}0.025$ inches in cross-section were divided into two groups (n = 50 each) according to composition, either stainless steel or beta-titanium. The two groups were further divided into five subgroups, 10 loops each, corresponding to the five preactivations tested: preactivations with occlusal distribution ($0^{\circ}$, $20^{\circ}$, and $40^{\circ}$), gingival distribution ($20^{\circ}$), and occlusal-gingival distribution ($40^{\circ}$). The loops were subjected to a total activation of 6-mm with 0.5-mm iterations. Statistical analysis was performed using comprised ANOVA and Bonferoni multiple comparison tests, with a significance level of 5%. Results: The location and intensity of preactivation influenced the force intensity. For the M/F ratio, the highest value achieved without preactivation was lower than the height of the loop. Without preactivation, the M/F ratio increased with activation, while the opposite effect was observed with preactivation. The increase in the M/F ratio was greater when the preactivation distribution was partially or fully gingival. Conclusions: Depending on the preactivation distribution, displacement of uprights is higher or lower than the activation, which is a factor to consider in clinical practice.

• 한국가축번식학회지
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• 제21권3호
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• pp.229-238
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• 1997

Chromosome condensation and swelling of the donor nucleus have been known as the early morphological indicators of chromatin remodelling after injection of a foreign nucleus into an enucleated recipient cytoplasm. The effects of non-preactivation and electrical preactivation of recipient cytoplasm, prior to fusing a donor nucleus, on the profile of nuclear remodelling in the nuclear transplant rabbit embryos were evaluated. The embryos of 16-cell stage were collected and synchronized to G1 phase of 32-cell stage. The recipient cytoplasms were obtained by removing the first polar body and chromosome mass by non-disruptive microsurgical procedure. The separated G1 phase blastomeres of 32-cell stage were injected into non-preactivated recipient cytoplasms. Otherwise, the enucleated recipient cytoplasms were preactivated by electrical stimulation and the separated G1 phase blastomeres of 32-cell stage were injected. After culture until 20h post-hCG injection, the nuclear transplant oocytes were electrofused by electrical stimulation. The nuclei of nuclear transplant embryos fused into non-preactivated and/or preactivated recipient cytoplasm were stained by Hoechst 33342 at 0, 1.5, 2, 4, 6, 8, 10 hrs post-fusion and were observed under an fluorescence microscopy. Accurate measurements of nuclear diameter were revealed with an ocular micrometer at 200$\times$. Upon blastomere fusion into non-preactivated recipient cytoplasm, a prematurely chromosome condensation at 1.5 hrs post-fusion and nuclear swelling at 8 hrs post-fusion were occurred as 91.6% and 86.1%, respectively. But the nuclei of nuclear transplant embryos fused into preactivated recipient cytoplasm, as o, pp.sed to non-preactivated recipient cytoplasm, were not occurred chromosome condensation and extensive nuclear swelling. Nuclear diameter fused into non-preactivated and preactivated recipient cytoplasm at hrs post-fusion was 30.2$\pm$0.74 and 15.2$\pm$1.32${\mu}{\textrm}{m}$, respectively. These results indicated that onset of unclear condensation and swelling which was associated with oocytes activation were critical steps in the process of chromatin swelling. Futhermore, complete reprogramming seemed only possible after remodelling of the donor nucleus by chromosome condensation and nuclear swelling.

• 한국수정란이식학회지
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• 제12권1호
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• pp.1-10
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• 1997

The present study was conducted to investigate the influence of embryo cell stage at 18h post-fusion and oocyte preactivation on sebsequent in vitro developmental potential in the nuclear transplant rabbit embryos. The embryos of 16-cell stage were collected and synchronized to G$_1$ phase of 32-cell stage. The recipient cytoplasms were obtained by removing the first polar body and chromosome rnass from the oocytes collected by non-dis-ruptive microsurgery procedure. The separated G$_1$ phase blastomeres of 32-cell stage were injected into non-preactivated recipient cytoplasms. Otherwise, the enucleated recipient cytoplasms were preactivated by electrical stimulation at 18h post-hCG injection and the separated G$_1$ phase blastomeres of 32-cell stage were injected. Mter culture until 20h post-hOG injection, the nuclear transplant oocytes were electrofused by electrical stimulation. The fused nuclear transplant embryos were classified into 3~4-cell, 2-cell and 1-cell stage at 18 hrs post-fusion and cultured until the embryos reached blastocyst stage. The developmental rate to blastocyst stage was significantly (P <0.05) higher in all the reconstituted embryos of 3~4-cell stage(58.0%) than in 2 and icell stage. The developmental rate to blastocyst stage in the embryos of 3~4-cell stage at 18 hrs post-fusion was significantly (P<0.05) higher in the reconstituted without oocyte preactivation(77.8%) than in the oocyte-preactivated embryos (33.3%). These results indicated that the higher rate of in the in vitro development to blastocyst stage might be obtained form the embryos which were reconstituted with nuclear donor of G$_1$ phase and non-preactivated oocyte, and developed more rapidly for 18 hrs post-fusion.

• 한국가축번식학회지
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• 제21권3호
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• pp.219-228
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• 1997

To examine the efficiency of nuclear transplantation the influence of electrical preactivation of recipient cytoplasm on the in vitro developmental potentyl in the nuclear transplant rabbit embryos were evaluated. The embryos of 16-cell stage were collected and synchronized to G1 phase of 32-cell stage. The recipient cytoplasms were obtained by removing the first polar body and chromosome mass by non-disruptive microsurgery procedure. The separated G1 phase blastomeres of 32-cell stage were put into the non-preactivated and/or the preactivated recipient cytoplasm by electrical stimulation. After culture until 20h post-hCG injection, the nuclear transplant oocytes were electrofused. The fused nuclear transplant embryos were co-cultured with rabbit oviduct epithelial cells and monitored every 24h to assess for developmental rate. After in vitro culture for 120h, the nuclear transplant embryos developed to blastocyst stage were stained with Hoechst 33342 and their blastomere were counted. The electrofusion rate was similar to the non-preactivated and preactivated recipient cytoplasm(81.8 and 85.7%, respectively). However, the in vitro developmental rate to blastocyst stage with the non-preactivated recipient cytoplasm (57.1%) was found significantly (P<0.05) higher, compared to the preactivated recipient cytoplasm(20.8%). The cell counts of nuclear transplant embryos developed to blastosyst stage were increased significantly (P<0.05) more in the non-preactivated recipient cytoplasm (163.7 cells), as compared with the preactivated recipient cytoplasm(85.4 cells). These results considered better that non-preactivated oocytes, MII phase oocytes, were used for recipient cytoplasms in the rabbit nuclear transplant procedure.

• PNF and Movement
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• 제2권1호
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• pp.25-33
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• 2004

Purpose : The purpose of this article is to summarize the characteristics of isotonic combination. Method : Some studies of the motor unit activation patterns during isometric, concentric, and eccentric actions, neural strategies in the control of muscle force, and concentric versus combined concentric-eccentric training were reviewed. Results & Conclusions : Eccentric torque may be relatively higher than concentric torque for two potential reasons: 1) stretch responses in the antagonist are not elicited to restrain the motion as can occur concentrically and 2) stretch responses in the agonist may augment eccentric torque production. Concentric-eccentric training has a greater influence on functional capacity than that of concentric training. Both maximal force and average force throughout the motion were significantly higher when the dynamic action was started with preactivation as compared to the mode without preactivation. The peak torques observed during the concentric phase of the eccentric-concentric muscle actions were higher than those noted in the pure concentric contraction.

• 한국수정란이식학회지
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• 제14권3호
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• pp.195-201
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• 1999

This study was carried out to improve a technique of cloned animal prodcution by preactivation of nuclear recipient oocytes with ionomycin and 6-dimethylaminopurine (6-DMAP) in rabbits. The oocytes were collected from the oviduct of superovulated rabbit at 19∼20 hours post hCG injection. The collected oocytes were preactivated and self-enucleated by treating 5 uM ionoycin for 5 min, and 2.0 mM 6-DMAP for two hours. Microsurgical removel of the chromation complex in the second polar bodies was effectively performd and single blastomere separated from 32-cell stage rabbit embryos was injected into the perivitelline space of the enculeated recipient oocyts. Follwoing electrofusion and in vitro culture for 18 hours, the nuclear transplant(NT) embryos were transferred into the uterine horns of naturally mated or synchronized recipient does. When 32 NT embryous reconstituted with preactivated oocytes were transferred to 2 recipient does, one foster doe delivered two offspring (6.3%), while not a offspring was delivered from three foster does which received 17 NT embryos reconstituted with non-preactivated oocytes. A total of 68 NT embryos reconstituted with preactivated oocytes were transferred into the uterine horns of 7 synchronized ecipient does. Among them, two recipients were pregnant and delivered three offspring(5.9%).

• 한국가축번식학회지
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• 제21권3호
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• pp.293-302
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• 1997

Follicular oocytes of Grade I and II were collected from 2~6 mm ovarian follicles and matured in vitro (IVM) for 24 hrs in TCM-199 su, pp.emented with 35$\mu\textrm{g}$/ml FSH, 10$\mu\textrm{g}$/ml LH, and 1$\mu\textrm{g}$/ml estradiol-17$\beta$ at 39$^{\circ}C$ under 5% CO2 in air. They were fretilized in vitro (IVF) by epididymal spermatozoa capacitated with heparin for 12 hrs. The zygotes were then co-cultured in vitro with bovine oviducted epithelial cells (BOEC) for 7 to 9 days. The optimal time for IVM, the successful enucleation of IVM oocytes by micromanipulation at different oocyte ages after IVM, and the ideal culture system for IVM for effective IVF and in vitro development of IVM-IVF embryos was examined for in vitro production of nuclear recipient oocytes and nuclear donor embryos. To improve the efficiency of nuclear transplantation (NT) of IVF embryo into IVM follicular oocytes, this study evaluated the optimal electric condition and oocytes age for activation of IVM oocytes and in vitro development of NT embryos. In vitro development of NT embryos with preactivation or non-preactivation in enucleation oocytes, cell number of IVN-IVF embryos, and NT embryos wre also examined. The results obtained were as follows; 1. The most suitable enucleation time was at 24 hpm (83.3%) rather than that of 28 hpm(69.6%) and 32 hpm(50.0%). 2. There was no difference among the fusion rates of NT embryos at the voltages of 0.75, 1.0 and 1.5 kV/cm, but the in vitro development rates to morule and blastocyst were significantly (P<0.05) higher at the voltage of 0.75(12.5%) and 1.0kV/cm (12.6%) compared to 1.5kV/cm(0%). 3. No significant difference in activation rates were seen in NT embryos stimulated for 30, 60 and 120 $\mu$sec (71.7, 85.2 and 71.9%, respectively), but the in vitro development rates to morulae and blastocyst were significantly (P<0.05) higher in the oocytes stimulated for 30 $\mu$sec (11.6%) and 60 $\mu$sec(10.7%) than 120 $\mu$sec(0.0%). 4. The fusion rates (71.0 and 87.3%) and the in vitro development rates (9.1 and 12.7%) to morula and blastocyst were seen in the NT embryos stimulated at 28 and 32 hpm under the condition of 1.0 kV/ml, 60 $\mu$sec. However, at 24 hpm the fusion rates were 64.8% and the in vitro development to morula and blastocyst were not seen. 5. The fusion rates between the 8~12, 13~17 and 18~22-cell stage of IVM-IVF embryos were not significantly different. The in vitro development rates of the fused embryos to morula and blastocyst which were received from a blastomere of 8~12, 13~17 and 18~22-cell stages of IVM-IVF embryos were 14.9, 8.3 and 6.5%, respectively. 6. The in vitro development rate of the enucleated recipient oocytes with preactivation (24.2%) to morula and blastocyst was significantly (P<0.05) higher than that of non-preactivation (12.8%). 7. The cell numbers of NT blastocyst and IVM-IVF blastocyst cultured during 7~9 days were 63$\pm$11 and 119$\pm$23, and then their the mean cell cycle number were 5.98 and 6.89, respectively.

• 대한방사성의약품학회지
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• 제5권2호
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• pp.158-162
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• 2019

[¹¹C]GR205171, a Neurokinin 1 (NK1) radioligand, has been known as such a promising PET probe for quantitation of NK1 receptors in the brain by positron emission tomography (PET) imaging. First trial to synthesis of [¹¹C]GR205171 was to use methylene chloride and tetrabutylammonium hydroxide for preactivation of precursor, but the result was not successful in radiochemical yield (0~25%) and unreliable. 7 years later, inorganic base (Cs₂CO₃) was tried to achieve higher radiochemical yield, and they showed higher yield (~53%). We have tried to repeat the same synthesis method, but it did not work properly, because there were the lack of the detail procedure and still reproducibility in radiochemical yield. Here we report the improved synthesis protocol to produce [¹¹C]GR205171 in high yield via commercial automated synthesizer. The sonicator which combines water heating bath was used to activate desmethyl-GR205171, and this method showed high efficiency and reasonable yields (4.7 ± 0.6%, non-decay corrected from molecular sieve trap) with >95% radiochemical purity.

• 한국임상수의학회지
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• 제16권1호
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• pp.163-176
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• 1999

The nuclear transplantation technique is known as the most potential and efficient method for producing large numbers of genetically identical animals from a single embryo and somatic cells. After Dolly was introduced in 1997, many scientists were amazed. A possibility came to a reality that live offspring could be produced with differentiated somatic cells from an adult animal. On the other side, many in the press and the sensationalists focused on the socially, ethically and scientifically unacceptable sides of the technology. In this article, the history, current status and prospects of the technological development of nuclear transplantation in mammals and its application to the production of cloned animals are described. For the efficient and successful production of cloned embryos by nuclear transplantation, the right selection, preactivation and micromanipulation of oocytes as capacious recipient cytoplasm, the adequate and benefitial preparation of multiple totipotent embryonic and somatic cells as donor nuclei, fusion of them and in vitro production of cloned embryos are very critical. Recently the overall efficiency of production of cloned embryos and offspring in livestock has been much improved. Cloning will also be a more efficient, faster and useful way of creating transgenic fetuses for gene therapies, gene pharming, organs for xenotransplantation by preselection and mass production of transgenic embryos and consequently improving the production efficiency in transgenic animals. Further technical development of nuclear transplantation will enable large-scale production of cloned livestock and in near future the commercial cloning of animals will become a reality.

• 대한수의학회지
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• 제38권3호
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• pp.652-658
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• 1998

The efficiency of nuclear transfer using donor embryos originated from ovum pickup(OPU) and activated recipient cytoplasts were examined for induction of twinning in Korean native cattle(KNC). After aspiration of follicle by OPU, regardless of the vacuum applied, we obtained same result in proportions of recovered cumulus-oocyte complex (COCs) with compact cumulus. Under electric stimulation(1.0kV/cm DC for $40{\mu}s$), most of activated oocytes proceed to anaphase II/telophase II within 3h(84.7%). In the treatment of oocyte activation, the preactivation which was performed before fusion had significant effect on the developmental rates to morula/blastocyst stage(9.4 vs 4.0%). In embryo transfer of nuclear transferred embryos, we obtained 2 twins from KNC recipients and 1 twin from a Holstein recipient. Our results showed that it is possible to obtain twins using nuclear transfer technique in KNC.