Skin entrance dose for digital and film radiography in Korean dental schools / 대한구강악안면방사선학회지

PURPOSE: This study was aimed to compare skin entrance dose of digital radiography with that of film radiography and to show the dose reduction achievement with digital systems at 11 dental schools in Korea. MATERIALS AND METHODS: Forty six intraoral radiographic systems in 11 dental schools were included in this study. Digital sensors were used in 33 systems and film was used in 13 systems. Researchers and the volunteer visited 11 dental schools in Korea. Researchers asked the radiologic technician (s) at each school to set the exposure parameters and aiming the x-ray tube for the periapical view of the mandibular molar of the volunteer. The skin entrance doses were measured at the same exposure parameters and distance by the technician for each system with a dosimeter (Multi-O-Meter : Unfors instruments, Billdal, Sweden). RESULTS: The median dose was 491.2micronGy for digital radiography and 1, 205.0 microGy for film radiography. The skin entrance dose in digital radiography was significantly lower than that of film radiography (p< 0.05). CONCLUSIONS: Fifty-nine percent skin entrance dose reduction with digital periapical radiography was achieved over the film radiography in Korean dental schools.

Proteomic analysis of the cellular proteins induced by adaptive concentrations of hydrogen peroxide in human U937 cells

When cells are first exposed to low levels of oxidative stress, they develop a resistance to a subsequent challenge of the same stress, even at higher levels. Although some protein(s) induced by oxidative stress likely mediated this adaptive response, the nature of these proteins is unknown. In this study, the total proteins extracted from human U937 leukemia cells exposed to 50 mM H2O2 for 24 h to induce an optimal protective response were analyzed by two-dimensional polyacrylamide gel electrophoresis. H2O2 treatment induced elevation of level of 34 protein spots. An analysis of these spots by a matrix associated laser desorption/ionization time-of-flight mass spectrometry identified 28 of the H2O2-induced proteins. These include proteins involved in energy metabolism, translation and RNA processing, chaperoning or mediating protein folding, cellular signaling, and redox regulation, as well as a mitochondrial channel component, and an actin-bundling protein. Therefore, it appears that the cellular adaptation to oxidative stress is a complex process, and is accompanied by a modulation of diverse cellular functions.