Role of ATF on Transcriptional Regulation of DNA Topoisomerase II a Gene in HL - 60 Arrested to G2 / M and M Phase / 대한암학회지

PURPOSE: To gain insight on transcriptional repression of Topo II a in HL-60 cells arrested to G2/M and M phase, the levels of Topo IIa mRNA and the binding activity of ATF have been investigated with Northern blot hybridization and DNA mobility shift assay, respectively. MATERIALS AND METHODS: HL-60 cells were grown in RPMI 1640 medium supplemented with 10% heat-mactivated fetal bovine serum and antibiotics in a humidified 5% CO2 at 37C degree. Total RNA was prepared by a modification of the method of Karlinsey et al. Northern blot hybridization was performed by the method of Virca et al. A Xho I-Mlu I fragment of phTOP2 was used as probe for Northern blot analysis of Topo II a mRNA. DNA mobility shift assay was performed by the method of Lim et al. End labeled DNA oligomer (upper strand, 5-TCTCCGCTATGACGCCGAGTGGTG-3) for ATF binding activity was mixed with nuclear extracts in a 20 pl reaction volume containing 60 mM KC1, 12 mM HEPES, pH 7.9, 5 mM MgCl2, 0.2 mM EDTA, 0.2 mM DTT, 12% glycerol, and 2 ug of poly [dI-dC]. RESULTS: HL-60 cells were arrested at G2/M phase and M phase after taxol or nocodazole treatment. The levels of Topo II a mRNA were reduced at 24 hours after exposure with nocodazole or taxol but the unknotting activities were not changed. DNA mobility shift assay using oligonucleotide containing the ATF binding site showed that ATF binding activity was reduced after pretreatment of nododazole or taxol. CONCLUSIONS: These results suggest that the reduction of ATF binding activity may be important to transcriptional repression of Topo II a gene by nocodazole and taxol in HL- 60 cells.

The Surgical Outcome of Clear Lens Extraction for Correction of High Myopia

In order to investigate the clinical results of clear lens extraction for high myopia, the effects of 5.5mm sutureless corneoscleral procedure with low power IOL insertion on 21 patients (31 eyes) who were followed up averagely for 9.43 months were analyzed retrospectively. Prophylactic retinal treatment with argon laser was performed in 23 eyes to prevent retinal detachment. Eighty-seven percent (25/31 eyes) of eyes were within +/-1D of targeted refractive error and all eyes were within +/-2D of targeted refractive error. The postoperative corrected visual acuities were increased in 96.8% (30/31 eyes) and 80.7% (25/31 eyes) among them gained two or more lines. the corrected visual acuity of 20/40 or better were increased from 35.5%(11/31 eyes) preoperatively to 93.6% (29/31 eyes) postoperatively. Posterior capsular opacification was developed in two eyes and YAG laser posterior capsulotomy was performed at 2 and 7 months postoperatively. No retinal break, no cystoid macular edema were developed during the follow up period. In conclusion, the clear lens extraction was effective method for correction of severe high myopia but longer follow-up is needed to evaluate it`s complications.