DNA damage in lens epithelial cells exposed to occupationally-relevant X-ray doses and role in cataract formation

The current framework of radiological protection of occupational exposed medical workers reduced the eye-lens equivalent dose limit from 150 to 20 mSv per year requiring an accurate dosimetric evaluation and an increase understanding of radiation induced effects on Lens cells considering the typical scenario of occupational exposed medical operators. Indeed, it is widely accepted that genomic damage of Lens epithelial cells (LEC) is a key mechanism of cataractogenesis. However, the relationship between apoptosis and cataractogenesis is still controversial. In this study biological and physical data are combined to improve the understanding of radiation induced effects on LEC. To characterize the occupational exposure of medical workers during angiographic procedures an INNOVA 4100 (General Electric Healthcare) equipment was used (scenario A). Additional experiments were conducted using a research tube (scenario B). For both scenarios, the frequencies of binucleated cells, micronuclei, p21-positive cells were assessed with different doses and dose rates. A Monte-Carlo study was conducted using a model for the photon generation with the X-ray tubes and with the Petri dishes considering the two different scenarios (A and B) to reproduce the experimental conditions and validate the irradiation setups to the cells. The simulation results have been tallied using the Monte Carlo code MCNP6. The spectral characteristics of the different X-ray beams have been estimated. All irradiated samples showed frequencies of micronuclei and p21-positive cells higher than the unirradiated controls. Differences in frequencies increased with the delivered dose measured with Gafchromic films XR-RV3. The spectrum incident on eye lens and Petri, as estimated with MCNP6, was in good agreement in the scenario A (confirming the experimental setup), while the mean energy spectrum was higher in the scenario B. Nevertheless, the response of LEC seemed mainly related to the measured absorbed dose. No effects on viability were detected. Our results support the hypothesis that apoptosis is not responsible for cataract induced by low doses of X-ray (i.e. 25 mGy) while the induction of transient p21 may interfere with the disassembly of the nuclear envelop in differentiating LEC, leading to cataract formation. Further studies are needed to better clarify the relationship we suggested between DNA damage, transient p21 induction and the inability of LEC enucleation

Application of phasor measurement units for monitoring power system dynamic performance

This Working Group is a sequel to a previous working group on Wide Area Monitoring and Control for Transmission Capability Enhancement, which published the Technical Brochure 330 in 2007. Since then the synchrophasor technology has advanced rapidly and many utilities around the world have installed hundreds of PMUs in their networks. In this Technical Brochure, we look at the current state of the technology and the extent to which it has been used in the industry. As the technology has matured, it is also important to understand the communication protocols used in synchrophasor networks and their relevant cyber-security issues. These concerns are briefly discussed in the brochure. The applications of Phasor Measurement Units (PMU) measurements reported here are divided into three categories: (a) applications already installed in utility networks, (b) applications that are well-tested, but not yet installed, and (c) applications that are beneficial to the industry, but not fully developed yet. The most common and mature applications are wide area monitoring, state estimation, and model validation. Out of these three applications, wide area monitoring is well established in the industry. The protection and control applications are emerging as evident from the reported examples. The experience of using remote synchrophasor measurements as feedback control signals is not widely reported by the industry. In parallel to this Working Group, Study Committee B5 had a Working Group on “Wide area protection and control technologies.” The Technical Brochure 664 published by this Working Group in September 2016 reviews synchrophasor technology and discusses the industry experience with wide area protection and control. The North American synchrophasor Initiative (NASPI) is another technical group that has gathered and reported a wide range of PMU experiences of industry and researchers. In summary, the field-tested applications presented in this Technical Brochure are a testimony to the confidence of utilities in the synchrophasor technology. The progress in state estimation techniques indicates that synchrophasor measurements will become a standard part of energy management and security assessment systems in the near future

Non-linear vibrations of nuclear fuel rods

Single zirconium alloy nuclear fuel rods with clamped-clamped boundary conditions and subjected to harmonic excitation at various force levels were experimentally studied. Different configurations were implemented, and the fuel rods were tested in air and submerged in quiescent water. Moreover, the effect of the contained fuel pellets was also reproduced by representative metallic pellets inside the rods. Non-linear stiffness and damping parameters were extracted from experimental vibration response curves by means of a specifically-developed identification tool. For the cases where the fuel pellets were removed or axially compressed, it was found that the axial-symmetry of the fuel rod resulted in a pronounced one-to-one internal resonance. The internal motion of the fuel pellets is a source of friction and impacts during vibrations, thus complicating further the linear and non-linear dynamic behavior of the system. A very significant increase of the viscous modal damping with the vibration amplitude was observed during geometrically non-linear vibrations, which is particularly relevant and in advantage of safety

Identification of non-linear vibration parameters of a nuclear fuel rod

In Pressurized Water Reactors (PWR), fuel assemblies are composed of fuel rods, long slender tubes filled with uranium pellets, bundled together using spacer grids. These structures are subjected to fluid-structure interactions, due to the flowing coolant surrounding the fuel assemblies inside the core, coupled with large-amplitude vibrations in case of external seismic excitation. Therefore, understanding the non-linear response of the structure and, particularly, its dissipation, is of paramount importance for the choice of safety margins. To model the nonlinear dynamic response of fuel rods, the identification of nonlinear stiffness and damping parameters is required. The case of a single fuel rod with clamped-clamped boundary conditions was investigated by applying harmonic excitation at various force levels. Different configurations were implemented testing the fuel rod in air and in still water; the effect of metal pellets simulating nuclear fuel pellets inside the rods was also recorded. Non-linear parameters were extracted from some of the experimental response curves by means of a numerical tool based on the harmonic balance method. The axisymmetric geometry of fuel rods resulted in the presence of a one-to-one internal resonance phenomenon, which has to be taken into account modifying accordingly the numerical identification tool. The internal motion of fuel pellets is a cause of friction and impacts, complicating further the linear and non-linear dynamic behavior of the system. An increase of the equivalent viscous-based modal damping with excitation amplitude is often shown during geometrically non-linear vibrations, thus confirming previous experimental findings in the literature

Virtual screening against nuclear factor \u3baB (NF-\u3baB) of a focus library: Identification of bioactive furocoumarin derivatives inhibiting NF-\u3baB dependent biological functions involved in cystic fibrosis.

In the present study, a structured-based virtual screening (VS) of differently substituted furocoumarins and analogues has been carried out against nuclear factor kappa B (NF-\u3baB), with the objective of selecting molecules able to inhibit the binding of this transcription factor to the DNA. The focus library was developed starting from chemical structures obtained from the literature, as well as retrieving compounds from available commercial databases. A two dimensional substructure searching method based on four different chemical scaffolds was used for this purpose. Among the 10 highest-scored ligands selected from the docking studies, five commercially available molecules were investigated in biological assays. Four furocoumarin derivatives showed IC(50) values in the range of 40-100 \u3bcM in inhibiting NF-\u3baB/DNA interactions studied by electrophoretic mobility shift assay (EMSA). Three compounds significantly inhibited NF-\u3baB dependent biological functions (expression of IL-8) in cellular analysis based on Pseudomonas aeruginosa infection of cystic fibrosis IB3-1 cells. These findings validated the virtual screening approach here presented and reinforce the successful results of our previously computational studies aimed at the identification of molecules targeting NF-\u3baB. The discovered novel compounds could be of relevance to identify more potent inhibitors of NF-\u3baB dependent biological functions beneficial to control lung inflammation occurring in patients affected by cystic fibrosis

Development of a Novel Furocoumarin Derivative Inhibiting NF-kB Dependent Biological Functions: Design, Synthesis and Biological Effects

Nuclear Factor kappaB (NF-\u3baB) plays a very important role in the control of gene expression and is deeply involved in several human pathologies. Accordingly, molecules targeting NF-\u3baB dependent biological functions are considered of great interest. Virtual screening of furocoumarin libraries against NF-\u3baB p50 allowed to rank compounds in respect to their expected ability to bind NF-\u3baB and the identified compound might be considered for the development of analogs to be tested for biological activity on inhibition of NF-\u3baB/DNA complex formation. The data reported in the present paper suggest that, following this approach, the best ranked compounds identified by virtual screening (a) strongly bind in silico to NF-\u3baB and (b) efficiently inhibit the molecular interactions between 32P-labeled NF-\u3baB double stranded DNA and p50 or p50/p65 complex. These data allowed to develop a novel lead of great interest for inhibiting NF-\u3baB dependent biological functions. This novel molecule (compound 2), bearing a methyl group in the 9 position of the psoralen nucleus, exhibits high efficiency in inhibiting NF-\u3baB/DNA interactions. In addition, we found that compound 2 is a potent inhibitor of IL-8 gene expression in TNF-\u3b1 treated IB3-1 cystic fibrosis cells. Taken together, our data indicate that compound 2 might find an important place in the set of molecules of interest for the development of pharmaceutical strategies against the inflammatory phenotype of cystic fibrosis

Virtual screening against nuclear factor kB (NF-kB) of a focus library: Identification of bioactive furocoumarin derivatives inhibiting NF-κB dependent biological functions involved in cystic fibrosis

In the present study, a structured-based virtual screening (VS) of differently substituted furocoumarins and analogues has been carried out against nuclear factor kappa B (NF-κB), with the objective of selecting molecules able to inhibit the binding of this transcription factor to the DNA. The focus library was developed starting from chemical structures obtained from the literature, as well as retrieving compounds from available commercial databases. A two dimensional substructure searching method based on four different chemical scaffolds was used for this purpose. Among the 10 highest-scored ligands selected from the docking studies, five commercially available molecules were investigated in biological assays. Four furocoumarin derivatives showed IC(50) values in the range of 40-100 μM in inhibiting NF-κB/DNA interactions studied by electrophoretic mobility shift assay (EMSA). Three compounds significantly inhibited NF-κB dependent biological functions (expression of IL-8) in cellular analysis based on Pseudomonas aeruginosa infection of cystic fibrosis IB3-1 cells. These findings validated the virtual screening approach here presented and reinforce the successful results of our previously computational studies aimed at the identification of molecules targeting NF-κB. The discovered novel compounds could be of relevance to identify more potent inhibitors of NF-κB dependent biological functions beneficial to control lung inflammation occurring in patients affected by cystic fibrosis

Development of a novel furocoumarin derivative inhibiting NF-κB dependent biological functions: Design, synthesis and biological effects

Nuclear Factor kappaB (NF-κB) plays a very important role in the control of gene expression and is deeply involved in several human pathologies. Accordingly, molecules targeting NF-κB dependent biological functions are considered of great interest. Virtual screening of furocoumarin libraries against NF-κB p50 allowed to rank compounds in respect to their expected ability to bind NF-κB and the identified compound might be considered for the development of analogs to be tested for biological activity on inhibition of NF-κB/DNA complex formation. The data reported in the present paper suggest that, following this approach, the best ranked compounds identified by virtual screening (a) strongly bind in silico to NF-κB and (b) efficiently inhibit the molecular interactions between (32)P-labeled NF-κB double stranded DNA and p50 or p50/p65 complex. These data allowed to develop a novel lead of great interest for inhibiting NF-κB dependent biological functions. This novel molecule (compound 2), bearing a methyl group in the 9 position of the psoralen nucleus, exhibits high efficiency in inhibiting NF-κB/DNA interactions. In addition, we found that compound 2 is a potent inhibitor of IL-8 gene expression in TNF-α treated IB3-1 cystic fibrosis cells. Taken together, our data indicate that compound 2 might find an important place in the set of molecules of interest for the development of pharmaceutical strategies against the inflammatory phenotype of cystic fibrosis

Targeting Transcription Factor Activity as a Strategy to Inhibit Pro-Inflammatory Genes Involved in Cystic Fibrosis: Decoy Oligonucleotides and Low-Molecular Weight Compounds

The development of drugs able to inhibit the expression of pro-inflammatory genes is of great interest in the treatment of cystic fibrosis (CF). Chronic pulmonary inflammation in the lungs of patients affected by CF is characterized by massive intra-bronchial infiltrates of neutrophils. This process is initiated upon interaction of pathogens (including Pseudomonas aeruginosa) with surface bronchial cells. Consequently, they release cytokines, the most represented being the potent neutrophilic chemokine Interleukin (IL)-8 and the pro-inflammatory cytokine IL-6. The chronic inflammatory process is crucial, since it leads to progressive tissue damage and severe respiratory insufficiency. In order to reduce the adverse effects of the excessive inflammatory response, one of the approaches leading to inhibition of IL-8 and IL-6 gene expression is the transcription factor (TF) decoy approach, based on intracellular delivery of double stranded oligodeoxynucleotides (ODNs) mimicking the binding sites of TFs and causing inhibition of binding of TFrelated proteins to regulatory sequences identified in the promoters of specific genes. Since the promoters of IL-8 and IL-6 contain consensus sequences for NF-κ B and Sp1, double stranded TF "decoy" ODNs targeting NF-κB and Sp1 can be used. Alternatively, screening of drugs targeting relevant TFs can be performed using drug cocktails constituted by extracts from medicinal plants inhibiting TF/DNA interactions. Finally, virtual screening might lead to identification of putative bioactive molecules to be validated using molecular and cellular approaches. By these means, low-molecular drugs targeting NF-κB and inhibiting IL-8 gene expression are available for pre-clinical testing using experimental systems recapitulating chronic pulmonary inflammation of patients affected by CF