Biomedical subjects

Jae Y Han

Publications and source records attributed to Jae Y Han.

6 recordsLinked to original sources

PubMed2005

Selective decrease of chick embryonic primordial germ cells in vivo and in vitro by soft X-ray irradiation.

The feasibility of soft (low-energy) X-ray irradiation as a means of depleting the endogenous primordial germ cell(s) (PGC) of chicken embryos, to improve the efficiency of germ cell-mediated transgenesis, was investigated. Eggs were subjected to a non-irradiated control treatment and embryos were exposed for 40s to soft X-ray at 15, 16.5, or 18 kV ( approximately 1.5, 1.65, and 1.8 Gy, respectively). Exposure of stage X embryos to each dose of X-ray resulted in a reduction of approximately 50% in the number of PGC apparent at stage 28, whereas the total number of gonadal cells was unaffected. Irradiation (16.5 kV) of embryos at stage 9 or 14 also resulted in similar decreases in the number of PGC with no effect on the total number of gonadal cells. Irradiation did not affect embryo hatchability, compared with the non-irradiated control treatment, although the hatch rate increased with the age of embryos at the time of irradiation. Exposure of gonadal cells isolated from stage 28 embryos to X-ray (16.5 kV, approximately 0.8 Gy) prevented the increase in PGC number during subsequent culture for 10 days; the increase in the total number of gonadal cells was not affected. In conclusion, exposure of chicken embryos to a low dose of soft X-rays is effective for depleting the endogenous PGC population without affecting embryo hatchability or somatic cell viability.

Animals↗

PubMed2005

Development of a hamster superovulation program and adverse effects of gonadotropins on microfilament formation during oocyte development.

OBJECTIVE: To establish a superovulation procedure for the golden hamster (Mesocricetus auratus) by elucidating gonadotropin effects on oocyte development. DESIGN: Randomized, prospective study. SETTING: University laboratory of embryology and gamete biotechnology. ANIMAL(S): Twelve- to 15-week-old female and sexually mature male hamsters. INTERVENTION(S): Different doses of pregnant mare serum gonadotropin (PMSG) were injected into female hamsters in metestrus, diestrus, or proestrus. The same dose of hCG was injected 56 hours later. MAIN OUTCOME MEASURE(S): Embryo development and oocyte morphology after treatment. RESULT(S): First, 10 IU or 15 IU each of PMSG and hCG was injected into 10 hamsters weighing <110 or 110-130 g, respectively. All hamsters were mated, but none delivered live young after injection. Second, the doses of 15 IU, 7.5 IU, 5 IU, or 0 IU of each gonadotropin were injected into each hamster (regardless of body weight, 5 per each group). Increasing numbers of embryos were retrieved as the dosage was increased (11.2 to 46.6 embryos per hamster), whereas the percentage of two-cell embryos at retrieval was significantly decreased (100% to 3%, P<.05). In subsequent culture, none developed to blastocysts after 15-IU injection, whereas 47%, 55%, and 70% of two-cell embryos developed after 7.5-IU, 5-IU, and 0-IU treatments, respectively. As a result, females injected with 5 IU yielded more blastocysts than did females without injection (67 vs. 39). The number of inner cell mass cells per blastocyst was greatly increased in the control groups compared with the 5-IU and 7.5-IU treatment groups (22 vs. 14.3-14.7 cells per blastocyst). Third, the ultrastructure of oocytes was examined after injecting 5 IU each of PMSG and hCG (regardless of body weight). Superovulation did not affect oocyte maturation, but different patterns in microfilament formation were detected after the treatment. CONCLUSION(S): Female hamsters can be superovulated effectively by injecting equal amounts of PMSG and hCG, 56 hours apart. However, embryo development was adversely affected in a dose-dependent manner at all doses of gonadotropins, and microfilament distribution was affected by such treatment.

Actin Cytoskeleton↗

PubMed2005

Expressed sequence tag analysis of Eimeria-stimulated intestinal intraepithelial lymphocytes in chickens.

Intraepithelial lymphocytes (IELs) play a critical role in protective immune response to intestinal pathogens such as Eimeria, the etiologic agent of avian coccidiosis. A list of genes expressed by intestinal IELs of Eimeria-infected chickens was compiled using the expressed sequence tag (EST) strategy. The 14,409 ESTs consisted of 1851 clusters and 7595 singletons, which revealed 9446 unique genes in the data set. Comparison of the sequence data with chicken DNA sequences in GenBank identified 125 novel clones. This EST library will provide a valuable resource for profiling global gene expression in normal and pathogen-infected chickens and identifying additional unique immune-related genes.

Animals↗

PubMed2004

Development of a nonmechanical enucleation method using x-ray irradiation in somatic cell nuclear transfer.

Irradiation of in-vitro-matured bovine oocytes with x-rays of different durations was performed to develop an alternative to conventional mechanical enucleation methods in somatic cell nuclear transfer. No significant difference in embryo development to the blastocyst stage was detected between nonmechanical and mechanical methods, and cytologic analyses of karyotype and microtubule formation showed the potential availability of x-ray irradiation.

Animals↗

PubMed2004

An interclass nuclear transfer between fowl and mammal: in vitro development of chicken-to-cattle interclass embryos and the detection of chicken genetic complements.

An attempt was made to develop an interclass somatic cell nuclear transfer method as an alternative means of establishing chicken embryonic stem cells. Chicken-to-cattle interclass embryos that activated calcium ionophore, cycloheximide, and cytochalasin D were developed into blastocysts, and the developing interclass embryos had chicken genetic complements.

Animals↗

PubMed2003

Electrical conductivity imaging by magnetic resonance electrical impedance tomography (MREIT).

Magnetic resonance electrical impedance tomography (MREIT) is a recently developed imaging technique that combines MRI and electrical impedance tomography (EIT). In MREIT, cross-sectional electrical conductivity images are reconstructed from the internal magnetic field density data produced inside an electrically conducting subject when an electrical current is injected into the subject. In this work the results of an electrical conductivity imaging experiment are presented, along with some practical considerations regarding MREIT. The MREIT experiment was performed with a 0.3 Tesla MRI system on a phantom made of two compartments with different electrical conductivities. The current density inside the phantom was measured by the MR current density imaging (MRCDI) technique. The measured current density was then used for conductivity image reconstruction by the J-substitution algorithm. The conductivity phantom images obtained with an injection current of 28mA showed conductivity errors of about 25.5%.

Algorithms↗