Assessment of bone dose response using ATR-FTIR spectroscopy: A potential method for biodosimetry.

The health care application of ionizing radiation has expanded worldwide during the last several decades. While the health impacts of ionizing radiation improved patient care, inaccurate handling of radiation technology is more prone to potential health risks. Therefore, the present study characterizes the bone dose response using bovine femurs from a slaughterhouse. The gamma irradiation was designed into low-doses (0.002, 0.004 and 0.007 kGy) and high-doses (1, 10, 15, 25, 35, 50 and 60 kGy), all samples received independent doses. The combination of FTIR spectroscopy and PLS-DA allows the detection of differences in the control group and the ionizing dose, as well as distinguishing between high and low radiation doses. In this way, our findings contribute to future studies of the dose response to track ionizing radiation effects on biological systems.

Effect of topical 5-ALA mediated photodynamic therapy on proliferation index of keratinocytes in 4-NQO-induced potentially malignant oral lesions.

Fractionation can improve photodynamic therapy (PDT) efficacy for potentially malignant oral lesion treatment. The aim of this study was to demonstrate the apoptosis/proliferation index of oral keratinocytes after two sessions of topical 5-ALA-mediated PDT in 4-Nitroquinoline-1-oxide-induced potentially malignant oral lesion, and to suggest the ideal interval between PDT sessions. Immuno-histochemical tests for proliferating cell nuclear antigen and caspase-3, and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay were performed at 6h, 24h, 48h, and 72h time intervals after PDT. The number of positive cells showing caspase-3 expression was significantly higher, mainly at 6h after PDT. In the first cycle of PDT, the highest frequency of positive cells for TUNEL was found at 24h. At 72h after PDT, proliferating cell nuclear antigen positive cells increased significantly, indicating that there was an epithelial response in direction towards DNA repair and cell proliferation at this time. Because cell proliferation increases and cell death index decreases at 72h after PDT, it is recommended that the interval between the PDT sessions must not be longer than 2days up to total lesion remission.

Dental discolouration after thermal treatment.

Enamel and dentin discolouration have extrinsic and intrinsic origins. Possible causes include pigmented food or drink, caries, clinical chemical treatments, trauma and, high temperature. In the oral cavity, dental hard tissues can be heated when irradiated with high-intensity lasers. This paper, reports initial results on the discolouration of enamel and dentin induced by thermal treatment. The samples used in this work were bovine incisor teeth. Enamel and dentin discolouration were verified using microscopy and transmission spectroscopy. Thermal treatment was carried out at temperatures of 140 and 200 degrees C. The natural transparent aspect of the enamel became opaque after thermal treatment, it whitened following treatment at 140 degrees C, and turned completely opaque after treatment at 200 degrees C. With the same thermal treatment, dentin became light brown after treatment, at 140 degrees C, and the brown pattern was more evident after treatment at 200 degrees C. Although there is no conclusive evidence, non-enzymatic browning, collagen denaturation or oxidation of some chemical component of the dentin, may be intensified or produced by the thermal treatment. In enamel, water loss and the consequent increase in light scattering explain the observed opacity.