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Sang Jun Uhm The Korean Society of Animal Reproduction and Biot 2023 한국동물생명공학회지 Vol.38 No.3
Background: The successful production of superior or transgenic offspring from in vitro produced embryos in cattle relies heavily on the quality of blastocyst stage embryos. In order to enhance the developmental competency of these embryos, a novel culture method was devised. Methods: This study utilized stem cell culture medium (SCM) from hESCs as a supplement within the culture medium for bovine in vitro produced embryos. To gauge the efficacy of this approach, in vitro fertilized embryos were subjected to culture in CR1aa medium enriched with one of three supplements: 0.3% BSA, 10% FBS, or 10% SCM. Results: The blastocyst development and hatching rates of one-cell zygotes cultured in CR1aa medium supplemented with SCM (23.9% and 10.2%) surpassed those cultured in CR1aa medium supplemented with BSA (9.3% and 0.0%) or FBS (3.1% and 0.0%) (p < 0.05). Furthermore, post-zygotic gene activation, cleaved embryos cultured in CR1aa medium supplemented with SCM (57.8% and 34.5%) exhibited notably higher rates (p < 0.05) compared to those cultured with BSA (12.9% and 0.0%) or FBS (45.7% and 22.5%) supplementation. Furthermore, the microinjection of SCM into the cytoplasm or pronucleus of fertilized zygotes resulted in elevated blastocyst development and hatching rates, particularly when the microinjected embryos were subsequently cultured in CR1aa medium supplemented with SCM from the 8-cell embryo stage onwards (p < 0.05), in contrast to those cultured with FBS supplementation. Conclusions: In conclusion, this study conclusively demonstrated that the incorporation of SCM into the culture medium significantly enhances the developmental progress of preimplantation embryos.
Further Results on Piecewise Constant Hazard Functions in Aalen's Additive Risk Model
Uhm, Dai-Ho,Jun, Sung-Hae The Korean Statistical Society 2012 응용통계연구 Vol.25 No.3
The modifications suggested in Uhm et al. (2011) are studied using a partly parametric version of Aalen's additive risk model. A follow-up time period is partitioned into intervals, and hazard functions are estimated as a piecewise constant in each interval. A maximum likelihood estimator by iteratively reweighted least squares and variance estimates are suggested based on the model as well as evaluated by simulations using mean square error and a coverage probability, respectively. In conclusion the modifications are needed when there are a small number of uncensored deaths in an interval to estimate the piecewise constant hazard function.
Uhm, Sang Jun,Gupta, Mukesh Kumar,Kim, Teoan,Lee, Hoon Taek JOHN WILEY & SONS LTD 2007 MOLECULAR REPRODUCTION AND DEVELOPMENT Vol.74 No.12
<P>Interspecies somatic cell nuclear transfer (iSCNT) has emerged as an important tool for studying nucleo-cytoplasmic interactions and cloning of animals whose oocytes are difficult to obtain. This study was designed to explore the feasibility of employing transgenic fibroblasts as donor cells for iSCNT. The study examined the chromatin morphology, in vitro development, and expression of an enhanced green fluorescent protein (EGFP) gene in porcine- and bovine-cloned embryos produced by iSCNT of fetal fibroblast transfected with a pLNβ-EGFP retroviral vector. Parthenogenetic and transfected or nontransfected intraspecies SCNT embryos were used as controls for comparison. Analysis of data revealed that xenogenic oocyte was able to reprogram somatic cells of different genus and supports their in vitro development to the blastocyst stage. However, the developmental rates of transgenic iSCNT embryos to the blastocyst stage were significantly lower than those of intraspecies SCNT embryos. The reduction in development rates was however, not due to integration of the transgene as the lower (P < 0.05) development rates of the intraspecies SCNT porcine or bovine embryos did not differ between transgenic and nontransgenic groups. Expression of EGFP was observed in 100% of blastocysts and mosaicism was not observed. Furthermore, after iSCNT of porcine or bovine donor nuclei into xenogenic ooplasm, patterns of nuclear remodeling in reconstructed embryos were similar. In conclusion, our data demonstrated the feasibility of producing transgenic iSCNT embryos. To our knowledge, this is the first report of transgenic cloned embryo production by iSCNT approach. In the future, this may provide a powerful research tool for studying developmental events in domestic animals and provide marked cell lines for other genetic manipulations. Mol. Reprod. Dev. 74: 1538–1547, 2007. © 2007 Wiley-Liss, Inc.</P>
Uhm, Sang Jun,Gupta, Mukesh Kumar,Chung, Hak-Jae,Kim, Jin Hoi,Park, Chankyu,Lee, Hoon Taek Asian Australasian Association of Animal Productio 2009 Animal Bioscience Vol.22 No.4
In vitro produced porcine embryos have potential application in reproductive biotechnology. However, their development potential has been very low. This study evaluated the in vitro developmental ability and quality of cloned and parthenogenetic porcine embryos having 2-4 cells or 5-8 cells on Day 2 of in vitro culture. Analysis of results showed that 2 to 4 cell embryos had higher ability to form blastocysts than 5 to 8 cell embryos (p<0.05). Blastocysts produced from culture of 2 to 4 cell embryos also contained higher cell numbers and had lower BAX:BCLxL transcript ratio than those produced from 5 to 8 cell embryos (p<0.05), thereby suggesting 2 to 4 cell embryos have higher development potential. Further investigation revealed that 5 to 8 cell embryos had higher incidence (100${\pm}$0.0%) of blastomeric fragmentation than 2 to 4 cell embryos (15.2${\pm}$5.5% for parthenogenetic and 27.7${\pm}$7.1% for cloned embryos). This suggests that low development potential of 5 to 8 cell embryos was associated with blastomeric fragmentation. In conclusion, we have shown that morphological selection of embryos based on cell number on Day 2 of in vitro culture could offer a practical and valuable non-invasive means to select good quality porcine embryos.
Uhm, Sang Jun,Gupta, Mukesh Kumar,Das, Ziban Chandra,Kim, Nam-Hyung,Lee, Hoon Taek Mary Ann Liebert 2011 Cellular reprogramming Vol.13 No.5
<P>UV-irradiation of oocytes during enucleation and serum starvation of donor cells during cell cycle synchronization may compromise the development competence of cloned embryos through excessive generation of reactive oxygen species (ROS). Here, we show that 3-hyroxyflavone (a flavonoid having hydroxyl group at 3 carbon position) inhibits UV- and serum starvation-induced ROS production in oocytes and donor cells, respectively, and thereby improves the in vitro development of cloned porcine embryos (p<0.05). In a parthenogenetic model, UV-irradiation for 5?sec or more was found to reduce the in vitro development and quality of the embryo, which could be rescued by their culture in the presence of 3-hydroxyflavone. The rescuing effect of 3-hydroxyflavone was associated with significant reduction in ROS level (14.41.0 vs. 47.16.7), increase in ERK signaling molecules by 2.1-fold, and decrease in Caspase3 expression by 3.2-fold. Culture of donor cells (18.51.4 vs. 13.01.7%) or cloned embryos (20.61.1 vs. 12.21.1%) in the presence of 3-hydroxflavone also increased (p<0.05) the rates of blastocyst formation in cloned embryos produced by the nuclear transfer of serum-starved donor cells into recipient cytoplasts exposed to UV-irradiation during the enucleation step. Importantly, both parthenotes and cloned embryos cultured in the presence of 3-hydroxyflavone had significantly increased ability to expand, and contained a higher number of cells than those of the control group (p<0.05). These results suggest that 3-hydroxyflavone may be useful for improving the in vitro developmental potential of cloned embryos through inhibition of ROS production induced by the UV-irradiation of oocyte and/or the serum starvation of donor cells.</P>