Biomedical subjects

Sun-Bok Lee

Publications and source records attributed to Sun-Bok Lee.

3 recordsLinked to original sources

PubMed2005

Automatic noise robust registration of radiographs for subtraction using strategic local correlation: an application to radiographs of dental implants.

Most of digital subtraction methods in dental radiography are based on registration using manual landmarks. We have developed an automatic registration method without using the manual selection of landmarks. By restricting a geometrical matching of images to a region of interest (ROI), we compare the cross-correlation coefficient only between the ROIs. The affine or perspective transform parameters satisfying maximum of cross-correlation between the local regions are searched iteratively by a fast searching strategy. The parameters are searched on the 14 scale image coarsely and then, the fine registration is performed on the original scale image. The developed method can match the images corrupted by Gaussian noise with the same accuracy for the images without any transform simulation. The registration accuracy of the perspective method shows a 17% improvement over the manual method. The application of the developed method to radiographs of dental implants provides an automatic noise robust registration with high accuracy in almost real time.

Dental Implants↗

PubMed2004

Nelumbinis Semen reverses a decrease in 5-HT1A receptor binding induced by chronic mild stress, a depression-like symptom.

Depression is associated with a dysfunctional serotonin (5-hydroxytryptamine; 5-HT) system. More recently, several lines of evidence suggest that an important factor in the development of depression may be a deficit in the function and expression of 5-HT1A receptors. The present study assessed if Nelumbinis Semen (N.s.) had an anti-depression effect through reversing a decrease in 5-HT1A receptor binding in rats with depression-like symptoms induced by chronic mild stress. Using a 5-HT1A receptor binding assay, with a specific 5-HT1A receptor agonist, 8-OH-DPAT (8-hydroxy-2-(di-n-propylamino) tetralin), the mechanism of the anti-depression effect of N.s. on rats was investigated, and the effects compared with two well-known antidepressants, Hyperium Perforatum (St. Johns Wort) and fluoxetine (Prozac). Animals were divided into five groups: the normal (N) group without chronic mild stress (CMS), the control (C) group under CMS for 8 weeks, the Nelumbinis Semen (N.s.) treatment group under CMS for 8 weeks, the Hyperium Perforatum (H.p.) treatment group under CMS for 8 weeks and finally, the fluoxetine (F) treatment group under CMS for 8 weeks. Each treatment was administered to rats during the last 4 weeks of the 8-week CMS. A sucrose intake test was performed to test the anti-depression effect of N.s. The N.s. treatment significantly reversed the decreased sucrose intake under CMS (P < 0.05 compared to control group under CMS). In the CA2 and CA3 regions of the hippocampus, both N.s. and H.p. reversed the CMS-induced decrease in 5-HT1A receptor binding. In the I to II regions of the frontal cortex, N.s. and H.p. also reversed the CMS-induced decrease in 5-HT1A receptor binding, and even showed a significant increase in 5-HT1A receptor binding compared to the F treatment group (N.s. vs. P, p < 0.05, H.p. vs. P, p < 0.05). However, in the hypothalamus, all treatments reversed the CMS-induced decrease in 5-HT1A receptor binding. This reversal effect of N.s. on the decrease in 5-HT1A receptor binding in the frontal cortex, hippocampus and hypothalamus of rat brains was very similar to that of H.p, but different from that of F. It is concluded that N.s. presents an anti-depression effect through enhancing 5-HT1A receptor binding.

8-Hydroxy-2-(di-n-propylamino)tetralin↗

PubMed2003

Effect of different temperatures and penetration depths of a System B plugger in the filling of artificially created oval canals.

OBJECTIVES: The purpose of this study was to compare the gutta-percha-filled area in oval canals while varying the temperature and penetration depth of the System B plugger. STUDY DESIGN: Seventy-five resin blocks, with artificially created oval canals, were obturated by using a continuous wave technique. In groups 1, 2, and 3, the plugger was introduced to a depth of 4 mm from the apex at set temperatures of 100, 200, and 350 degrees C, respectively. In group 4, the plugger was inserted to a depth of 2 mm from the apex at a set temperature of 200 degrees C. Group 5 was obturated in the same way as group 2, and then an additional cold plugging was performed to a depth of 3 mm from the apex. The cross sections of the obturated canals were photographed, and the percentage of the gutta-percha-filled area (PGP) was measured. RESULTS: No significant differences were found between the 3 different temperature settings (P >.05). At 1 mm from the apex, group 4 showed the highest PGP (95.57% +/- 6.86), followed by group 5 (84.72% +/- 12.19), and group 2 (67.33 +/- 13.03) (P <.05). CONCLUSION: In artificially created oval canals, plugger temperature within the range used in this study did not affect the PGP. However, the penetration depth of the plugger was significantly related to PGP.

Acrylic Resins↗