BACKGROUND: Eradication of endodontic biofilms from the infected root canal system is still the main concern in endodontics. In this study, the role of the power density parameter in the efficacy of antimicrobial photodynamic therapy (PDT) with toluidine blue O (TBO) and phycocyanin (PC) activated by a 635 nm diode laser (DL) against Enterococcus faecalis biofilm in the root canal model was investigated.
METHODS: The E. faecalis biofilm in the root canal was treated with TBO and PC with different power densities (636, 954, 1273, and 1592 W/cm2). The untreated biofilm represented the control group. After the treatments, the biofilms were analyzed based on the number of colonies per milliliter.
RESULTS: TBO and PC activated with 635 nm DL with a power density of 1592 W/cm2 were more efficient in removing E. faecalis biofilms within the root canals than those with a power density of 636 W/cm2 (p = 0.00).
CONCLUSIONS: The light power density optimized the bacterial reduction of E. faecalis biofilms in the root canal spaces. These results provide information on the decisive parameters for performing PDT on intracanal biofilms.

The comprehensive genomic impact of ionizing radiation (IR), a carcinogen, on healthy somatic cells remains unclear. Using large-scale whole-genome sequencing (WGS) of clones expanded from irradiated murine and human single cells, we revealed that IR induces a characteristic spectrum of short insertions or deletions (indels) and structural variations (SVs), including balanced inversions, translocations, composite SVs (deletion-insertion, deletion-inversion, and deletion-translocation composites), and complex genomic rearrangements (CGRs), including chromoplexy, chromothripsis, and SV by breakage-fusion-bridge cycles. Our findings suggest that 1 Gy IR exposure causes an average of 2.33 mutational events per Gb genome, comprising 2.15 indels, 0.17 SVs, and 0.01 CGRs, despite a high level of inter-cellular stochasticity. The mutational burden was dependent on total irradiation dose, regardless of dose rate or cell type. The findings were further validated in IR-induced secondary cancers and single cells without clonalization. Overall, our study highlights a comprehensive and clear picture of IR effects on normal mammalian genomes.

Different sterilization doses of the electron beam (E-beam) will change the properties of biomaterials and affect their clinical application. Acellular porcine cornea (APC) is a promising corneal substitute to alleviate the shortage of corneal resources. The residual DNA was significantly reduced to 18.50 ± 3.19 ng/mg, and the clearance rate of α-Gal was close to 100% after the treatment with freezing-thawing combined enzyme, indicating that the decellularization was effective. The effects of different E-beam doses at 0, 2, 8, 15, and 25 kGy on the APC were studied. With the increase in irradiation dose, the transmittance, tensile strength, and swelling ratio of APC gradually decreased, but the resistance to enzymatic degradation was stronger than that of non-irradiated APC, especially at 8 kGy. The structure of APC was denser after irradiation, but the dose of 25 kGy could cause partial collagen fiber fracture and increase the pore size. The cell viability of the APC irradiated by 15 and 25 kGy were greater than 80%. After the implantation in rabbit corneas, there was no obvious neovascularization and inflammation, but the dose of 25 kGy had a more destructive effect on the chemical bonds of collagen, which made the APC easier to be degraded. The thickness of APC in the 25 kGy group was thinner than that in the 15 kGy group 1 year after surgery, and the epithelium grew more slowly, so the E-beam dose of 15 kGy might be more suitable for the sterilization of APC.

To evaluate the shrinkage rate of small cervical lymph nodes (SCLNs) at different levels in patients with nasopharyngeal carcinoma (NPC) treated with radiotherapy retrospectively. 96 adult patients with NPC who underwent intensity-modulated radiotherapy (IMRT) at our institution were analyzed and followed-up. Evaluation of the response (shrinking rate) of SCLNs was determined by the bidimensional tumor area. Binary logistic regression was conducted to explore the risk factors associated with the shrinking rate of SCLNs. Of the 96 patients included in this study, 1,194 SCLNs were identified. Among the SCLNs, 28.6% were level IIb and 21.3% were level IIa. SCLNs at level IIa (96.1%), tended to have a response effect of no change (NC) with shrinking rate <50% (odds ratio [OR]=0.007; 95% CI: 0.003-0.021, P=5.287×10-25). Conversely, the most proportionate share of SCLNs for shrinking rate ≥50% (complete response (CR) or partial response (PR)) was observed at level IIb (67.2%) (OR=6.104; 95% CI: 3.267-11.407, P=1.420×10-8). There was no significant difference of shrinking rate between irradiation doses of 60Gy and 63Gy. Most SCLNs at level IIa were not shrunk after radiotherapy. The irradiation dose of SCLNs at level IIa should be not more than 60Gy to reduce side effects.

The work investigates the effects of CO2 laser parameters (laser power and raster density) on wood mass loss in oak wood and impacts on its morphology, chemical structure, and surface properties (colour and hydrophilicity). The energy amount supplied onto the wood surface with a laser beam under different combinations of the irradiation parameters was expressed through a single variable-total irradiation dose. The mass loss was confirmed as linear-dependent on the irradiation dose. With the mass reduction, the roughness was enhanced. The roughness parameters Ra and Rz increased linearly with the mass loss associated with the increasing irradiation dose. The FTIR (Fourier transform infrared spectroscopy) spectroscopy also detected chemical changes in the main wood components, influencing primarily the wood colour space. Conspicuous discolouration of the engraved wood surface was observed, occurring just at the minimum laser power and raster density. The additional increasing of laser parameters caused a novel colour compared to the original one. The detected dependence of wood discolouration on the total irradiation dose enables us to perform targeted discolouration of the oak wood. The engraved surfaces manifested significantly better wettability with standard liquids, both polar and non-polar, and higher surface energy values. This guarantees appropriate adhesion of film-forming materials to wood. Identification of the changes in wood surface structure and properties, induced by specific CO2 laser-treatments, is important for obtaining targeted discolouration of the wood surface as well as for the gluing or finishing of the surfaces treated in this way.

The ionising radiation created by high intensity and high repetition rate lasers can cause significant radiological hazard. Earlier defined electron temperature scalings are used for dose characterisation and prediction using Monte Carlo modelling. Dosimetric implications of different electron temperature scalings are investigated and the resulting equivalent doses are compared. It was found that scaling defined by Beget al(1997Phys. Plasmas4447-57) predicts the highest electron temperatures for given intensities, and subsequently the highest doses. The atomic number of the target, x-ray generation efficiency and interaction volume are the other parameters necessary for the dose evaluation. The set of these operational parameters should be sufficient to characterise radiological characteristics of ultrashort laser pulse based x-ray generators and evaluate radiological hazards of the laser processing facilities.

Protons may have contributed to the evolution of plants as a major component of cosmic-rays and also have been used for mutagenesis in plants. Although the mutagenic effect of protons has been well-characterized in animals, no comprehensive phenotypic and genomic analyses has been reported in plants. Here, we investigated the phenotypes and whole genome sequences of Arabidopsis M2 lines derived by irradiation with proton beams and gamma-rays, to determine unique characteristics of proton beams in mutagenesis. We found that mutation frequency was dependent on the irradiation doses of both proton beams and gamma-rays. On the basis of the relationship between survival and mutation rates, we hypothesized that there may be a mutation rate threshold for survived individuals after irradiation. There were no significant differences between the total mutation rates in groups derived using proton beam or gamma-ray irradiation at doses that had similar impacts on survival rate. However, proton beam irradiation resulted in a broader mutant phenotype spectrum than gamma-ray irradiation, and proton beams generated more DNA structural variations (SVs) than gamma-rays. The most frequent SV was inversion. Most of the inversion junctions contained sequences with microhomology and were associated with the deletion of only a few nucleotides, which implies that preferential use of microhomology in non-homologous end joining was likely to be responsible for the SVs. These results show that protons, as particles with low linear energy transfer (LET), have unique characteristics in mutagenesis that partially overlap with those of low-LET gamma-rays and high-LET heavy ions in different respects.

OBJECTIVE: To investigate the doses of total body (TBI) and whole abdominal irradiation (WAI) induced lethal intestinal injury, healthy C57BL/6 J mice were divided randomly into 7 groups: control group; 6, 7, and 8 Gy TBI groups; and 5, 10, and 15 Gy WAI groups. The survival length, general conditions, body weight, daily food and water intake of the mice and the histopathological changes of small intestine were observed.
RESULTS: Lethal injury among C57BL/6 J mice was caused by ≥6 Gy TBI and 15 Gy WAI. Their body weight and food intake decreased, the structure of their small intestinal villi was destroyed, and the number of surviving crypts per circumference of the jejunum decreased in ≥6 Gy TBI groups and 15 Gy WAI group. The mice in the 10 Gy WAI group significantly lost weight within 5 days but recovered slowly thereafter. They also had poor appetite and reversibly damaged intestinal mucosa.
CONCLUSIONS: Nonlethal intestinal injury could be induced by 10 Gy WAI, whereas lethal intestinal injury could be triggered by ≥6 Gy TBI and >15 Gy WAI in mice. Our results provided a basis for establishing radiation-induced intestinal injury models with C57BL/6 J mice.

This study investigated the effect of irradiation (0, 3, 5 or 7 kGy) on the tenderness changes of pork during storage at 4 °C for two weeks by determining the total carbonyl, sulfhydryl groups, peptidomic profiles, Warner-Bratzler (WB) shear force value and by gel electrophoresis (SDS-PAGE) experiment. The results showed that, irradiation significantly increased total carbonyl content of pork but had no significant effect on sulfhydryl groups. Protein thiol loss induced by irradiation was greatly promoted after storage for 3 days. Increasing irradiation dose level could significantly decrease the WB shear force value of samples (P < .05) by provoking degradation of myofibrillar protein and collagen fragments. During refrigerated conditioning, however, the WB shear force values increased significantly despite irradiation (P < .05). This was attributed to increasing amount of collagen solubilized from muscle, protein aggregation induced by carbonylation of troponin T (at 7 days of storage) and further cross-linking of myosin heavy chain (MHC) (at 14 days of storage).

OBJECTIVE: The aim of the study was an evaluation of I-125 brachytherapy patients with uveal melanoma with special consideration for the relationship of the treatment results and the irradiation dose applied to the tumor apex.
METHODS: Medical records of 344 adults with uveal melanoma treated with I-125 brachytherapy in the Department of Ophthalmology and Ocular Oncology of the Jagiellonian University, Medical College in Cracow, Poland were retrospectively analyzed. The study was conducted between 2003 and 2012, and the study group was divided into two subgroups depending on the irradiation dose applied to the top of the tumor: 80 Gy to 100 Gy (n = 177) and 100 Gy to 120 Gy (n = 167).
RESULTS: It was found that the height of the tumor and the largest diameter of the tumor base decreased with every consecutive follow-up measurement and differed significantly in all comparisons (p < 0.0001). No significant correlation between frequency of complications was found between both study groups (χ2 = 0.27; p = 0.6067). The correlation between survival and the irradiation dose as applied to the tumor top was statistically irrelevant (χ2 = 0.44; p = 0.5084). A logistic regression model showed that patient survival depended on the largest diameter of the base and the height of tumor (p = 0.0216), and the risk of death was larger as these dimensions increased (IR, 1.17). An increase of the largest diameter of the base by 1 mm meant a 17% increase in chances of death. In 13.4% of cases, an enucleation was necessary.
CONCLUSIONS: The treatment of choroidal melanomas with I-125 iodine isotope brachytherapy is an efficient and recommended method of treatment and in many cases, an alternative to the enucleation of an eyeball.