Three-dimensional analysis of biplanar cephalograms.

The aims of this study were to reconstruct a three-dimensional (3D) model, to provide a 3D analysis using biplanar cephalograms [postero-anterior (PA) and lateral] with orthogonal projection, and to compare the differences between the 3D and two-dimensional (2D) analyses. The procedures were as follows: (1) to identify landmarks from a dry skull and to construct the norms for the spatial information of the skull from the 3D reconstruction using computerized tomography (CT); (2) to reconstruct a 3D model using biplanar cephalograms (PA and lateral); and (3) to compare the differences between the 2D and 3D analyses. Fifteen clearly visible landmarks identified on both films were used in this study. By comparing the data from the CT and the biplanar cephalograms, it was found that the accuracy for the 3D linear measurements from biplanar cephalograms was 98.9 per cent. However, the accuracy for the linear measurements from 2D and CT data was only 89.2 per cent. If the measurement of gonion (Go) to menton (Me) was excluded, the accuracy for the linear measurements from 2D and CT data was 95.1 per cent. When using a t-test to compare the linear distances of 2D-CT and 3D-CT data (Go to Me excluded), the difference was statistically significant (P < 0.05). The findings indicate that biplanar cephalograms with orthogonal projection are able to provide a 3D analysis that is more accurate than 2D analysis.

Changes in membrane cholesterol of pituitary tumor (GH3) cells regulate the activity of large-conductance Ca2+-activated K+ channels.

The effects of changes in membrane cholesterol on ion currents were investigated in pituitary GH3 cells. Depletion of membrane cholesterol by exposing cells to methyl-beta-cyclodextrin (MbetaCD), an oligosaccharide, resulted in an increase in the density of Ca2+-activated K+ current (IK(Ca)). However, no significant change in IK(Ca) density was demonstrated in GH3 cells treated with a mixture of MbetaCD and cholesterol. Cholesterol depletion with MbetaCD (1.5 mg/ml) slightly suppressed the density of voltage-dependent L-type Ca2+ current. In inside-out patches recorded from MbetaCD-treated cells, the activity of large-conductance Ca2+-activated K+ (BK(Ca)) channels was enhanced with no change in single-channel conductance. In MbetaCD-treated cells, voltage-sensitivity of BK(Ca) channels was increased; however, no change in Ca2+-sensitivity could be demonstrated. A negative correlation between adjacent closed and open times in BK(Ca) channels was observed in MbetaCD-treated cells. In inside-out patches from MbetaCD-treated cells, dexamethasone (30 microM) applied to the intracellular surface did not increase BK(Ca)-channel activity, although caffeic acid phenethyl ester and cilostazol still opened its probability effectively. However, no modification in the activity of ATP-sensitive K+ channels could be seen in MbetaCD-treated cells. Current-clamp recordings demonstrated that the cholesterol depletion maneuver with MbetaCD reduced the firing of action potentials. Therefore, the increase in BK(Ca)-channel activity induced by membrane depletion may influence the functional activities of neurons or neuroendocrine cells if similar results occur in vivo.

Tissue image interpolation based on fractional Brownian motion.

Fractal Brownian Motion (fBm) has been proven in a viewpoint of irregularity characterization for quantifying the structure of the tissue images. Breast masses were selected as the target sample because breast-associated diseases have become prevalent in Taiwan. In this paper, the ability of fractal dimension in fractal interpolation schemes is investigated and compared with the traditional interpolation schemes including bilinear and bicubic methods. Using three image quality indices the difference between original and interpolated images may have evaluated. Interpolated images by fractal interpolation can maintain fractal characteristics better than traditional interpolation methods. Fractal features can be preserved in the interpolated images. Thus, interpolated tissue images based on fBm model are superior to conventional methods.