Long-term effects of tongue piercing — a case control study

The aim of this study was to evaluate tooth and periodontal damage in subjects wearing a tongue piercing (TP) in comparison to matched control subjects without tongue piercing. Members of the German Federal Armed Forces who had TP (group TP) and a matched control group (group C) volunteered to take part in the study. The time in situ, localization and material of TP were documented. Dental examinations included DMF-T, oral hygiene, enamel fissures (EF), enamel cracks (EC) and recessions. Statistical analysis was determined by χ2 test and the t test. Both groups had 46 male subjects (mean age 22.1 years). The piercings had been in situ for 3.8 ± 3.1 years. Subjects in the TP group had a total of 1,260 teeth. Twenty-nine subjects had 115 teeth (9.1%) with EF (67% lingual). In group C (1,243 teeth), 30 subjects had 60 teeth with EF (4.8%, 78% vestibular) (p < 0.01). Thirty-eight subjects belonging to group TP had EC in 186 teeth (15%). In group C, 26 subjects with 56 teeth (4.5%) were affected by EC (p < 0.001). Twenty-seven subjects in group TP had 97 teeth (7.7%) with recessions. Lingual surfaces of anterior teeth in the lower jaw were affected most frequently (74%). In group C, 8 subjects had 19 teeth (1.5%) with recessions (65% vestibular). Differences between the two groups were statistically significant (p < 0.001). Tongue piercing is correlated with an increased occurrence of enamel fissures, enamel cracks and lingual recessions. Patients need better information on the potential complications associated with tongue piercing

Induction and processing of the radiation-induced gamma-H2AX signal and Its link to the underlying pattern of DSB: A combined experimental and modelling study

We present here an analysis of DSB induction and processing after irradiation with X-rays in an extended dose range based on the use of the γH2AX assay. The study was performed by quantitative flow cytometry measurements, since the use of foci counting would result in reasonable accuracy only in a limited dose range of a few Gy. The experimental data are complemented by a theoretical analysis based on the GLOBLE model. In fact, original aim of the study was to test GLOBLE predictions against new experimental data, in order to contribute to the validation of the model. Specifically, the γH2AX signal kinetics has been investigated up to 24 h after exposure to increasing photon doses between 2 and 500 Gy. The prolonged persistence of the signal at high doses strongly suggests dose dependence in DSB processing after low LET irradiation. Importantly, in the framework of our modelling analysis, this is related to a gradually increased fraction of DSB clustering at the micrometre scale. The parallel study of γH2AX dose response curves shows the onset of a pronounced saturation in two cell lines at a dose of about 20 Gy. This dose is much lower than expected according to model predictions based on the values usually adopted for the DSB induction yield (≈ 30 DSB/Gy) and for the γH2AX foci extension of approximately 2 Mbp around the DSB. We show and discuss how theoretical predictions and experimental findings can be in principle reconciled by combining an increased DSB induction yield with the assumption of a larger genomic extension for the single phosphorylated regions. As an alternative approach, we also considered in our model the possibility of a 3D spreading-mechanism of the H2AX phosphorylation around the induced DSB, and applied it to the analysis of both the aspects considered. Our results are found to be supportive for the basic assumptions on which GLOBLE is built. Apart from giving new insights into the H2AX phosphorylation process, experiments performed at high doses are of relevance in the context of radiation therapy, where hypo-fractionated schemes become increasingly popular

Measurement of the fluorescence lifetime of GFP in high refractive index levitated droplets using FLIM

Green fluorescent protein (GFP) is a widely used fluorescent probe in the life sciences and biosciences due to its high quantum yield and extinction coefficient, and its ability to bind to biological systems of interest. This study measures the fluorescence lifetime of GFP in sucrose/water solutions of known molarity in order to determine the refractive index dependent lifetime of GFP. A range of refractive indices from 1.43-1.53 were probed by levitating micron sized droplets composed of water/sucrose/GFP in an optical trap under well-constrained conditions of relative humidity. This setup allows for the first reported measurements of the fluorescence lifetime of GFP at refractive indices greater than 1.46. The results obtained at refractive indices less than 1.46 show good agreement with previous studies. Further experiments that trapped droplets of deionised water containing GFP allowed the hygroscopic properties of GFP to be measured. GFP is found to be mildly hygroscopic by mass, but the high ratio of molecular masses of GFP to water (ca. 1500 : 1) signifies that water uptake is large on a per-mole basis. Hygroscopic properties are verified using brightfield microscope imaging, of GFP droplets at low and high relative humidity, by measuring the humidity dependent droplet size. In addition, this experiment allowed the refractive index of pure GFP to be estimated for the first time (1.72 ± 0.07). This work provides reference data for future experiments involving GFP, especially for those conducted in high refractive index media. The work also demonstrates that GFP can be used as a probe for aerosol studies, which require determination of the refractive index of the aerosol of any shape