Death-associated Protein 3 Regulates Mitochondrial-encoded Protein Synthesis and Mitochondrial Dynamics.

Mitochondrial morphologies change over time and are tightly regulated by dynamic machinery proteins such as dynamin-related protein 1 (Drp1), mitofusion 1/2, and optic atrophy 1 (OPA1). However, the detailed mechanisms of how these molecules cooperate to mediate fission and fusion remain elusive. DAP3 is a mitochondrial ribosomal protein that involves in apoptosis, but its biological function has not been well characterized. Here, we demonstrate that DAP3 specifically localizes in the mitochondrial matrix. Knockdown of DAP3 in mitochondria leads to defects in mitochondrial-encoded protein synthesis and abnormal mitochondrial dynamics. Moreover, depletion of DAP3 dramatically decreases the phosphorylation of Drp1 at Ser-637 on mitochondria, enhancing the retention time of Drp1 puncta on mitochondria during the fission process. Furthermore, autophagy is inhibited in the DAP3-depleted cells, which sensitizes cells to different types of death stimuli. Together, our results suggest that DAP3 plays important roles in mitochondrial function and dynamics, providing new insights into the mechanism of a mitochondrial ribosomal protein function in cell death.

Subjective and photometric determination of bleaching outcomes.

OBJECTIVE: Subjective and objective measures were used to determine the relative efficacy of 10% and 35% carbamide peroxide gels in bleaching extracted human teeth. METHOD AND MATERIALS: Fifty-five teeth (premolars and molars) were sectioned longitudinally, and one-half of each tooth was assigned to group A (10%) and the other half to group B (35%). Prebleaching shades were evaluated subjectively by 5 experienced observers using standard shade tabs. Photographs were also taken with a calibrated digital camera. Luminosity, R, G, and B levels were determined with Photoshop software. The specimens were then bleached by either 10% or 35% carbamide peroxide, after which they were reexamined by the 5 observers and rephotographed. RESULTS: All bleached specimens were subjectively assessed as "lighter", but there was no perceived difference in final shade between groups. Objective measurement showed that the greatest spread in the 0 to 255 scales was in the B levels. Mean (and range) of pre- and postbleaching B levels and their differences, by group, were group A, 96.2 (76.5 to 117.1), 113.6 (87.7 to 129.1), difference 17.4, and group B, 95.4 (72.1 to 118.8), 110.5 (88.0 to 138.5), difference 15.1. Statistics were performed using paired t tests. These pre- and postbleaching differences were significant (P < .002). The difference between mean postbleaching B values was not significant (P = .479). The greatest change in luminosity occurred in initially dark teeth treated with 35% carbamide peroxide (P = .036). CONCLUSIONS: Subjective determinations suggest that the bleaching protocols tested were equally effective, but the objective measurements implied that the higher concentration of carbamide peroxide was more effective for darker teeth.

Brightness (value) sequence for the Vita Lumin Classic shade guide reassessed.

The purpose of this study was to locate the 16 shade tabs from the Vita Lumin 'Classic' shade guide within the quantitative Luminosity, R, G and B scales (0-255 scales) using Photoshop software. A new value order arranged according to the Photoshop scale demonstrated a more linear relationship between the 16 shade tabs than the order given by the manufacturer. A Brightness Index representing the percentage difference in value between pairs of reordered shade tabs is suggested as a more realistic determinant of change in shade tab value.

Protective effect of grape seed extracts on human lymphocytes: a preliminary study.

Grape seed extracts (GSEs) possess a broad spectrum of antioxidative properties that protects various cells from free radicals and oxidative stress. In this study, the genoprotective effect of GSE on human lymphocytic DNA was studied using standard and lysed cell comet assays. Lymphocytes from 5 healthy subjects were pretreated with GSE in different concentrations. The standard and lysed cell comet assays were performed on treated, untreated, challenged, and unchallenged cells in parallel. Cells were then subjected to an oxidant challenge induced with 5-min exposures to hydrogen peroxide. In the standard comet assay, GSE significantly diminished hydrogen-peroxide-induced DNA damage in a dose-dependent manner. In the lysed cell assay, however, the antioxidant effect was diminished at a higher GSE concentration. Data indicate that the cell membrane might play a role in limiting cellular access to antioxidants, which directly affects the genoprotective or potential pro-oxidant effect of antioxidants on human DNA. Using both standard and lysed cell comet assays in parallel could be a useful way to elucidate the mechanism of protection or damage by antioxidants.