Influence of G4 Poly(Amidoamine)-Gold Nanocomposites on <i>Arthrospira platensis</i>

Human papillomavirus (HPV) infection represents the most important risk factor for cervical carcinoma. Levels of expression of E6 and E7 transforming oncoproteins of high risk HPV genotypes (i.e., HPV-16 and HPV-18) have been linked specifically to the mitotic activity of cervical carcinoma and appear to be necessary for maintaining the malignant phenotype. However, E6/E7 viral proteins recently have been reported to be effective tumor rejection antigens in animal models and humans. Radiation treatment represents a standardized and effective modality for contemporary cervical carcinoma therapy. However, although the physiologic and cellular changes associated with high doses of irradiation have been well documented it has been shown only recently that an increased synthesis of specific cellular proteins is observed after irradiation. In this study, the authors analyzed the effects of high doses of gamma irradiation on the expression of E6/E7 oncoproteins in HPV-16-infected cervical carcinoma cell lines. In addition, the effects of radiation on major histocompatibility complex (MHC) restriction elements also were studied. The effect of high doses of gamma irradiation (i.e., 1250, 2500, 5000, and 10,000 centigray [cGy]) on the kinetics of E6/E7 oncoprotein expression in two HPV-16 positive cervical carcinoma cell lines (i.e., CaSki and SiHa) was evaluated by Northern blot analysis. In addition, the effect of radiation on the expression of MHC molecules also was studied by Northern blot and fluorescence activator cell sorter (FACS) analysis. Dose ranging from 1250 (sublethal) to 10,000 (lethal) cGy significantly increased the expression of E6/E7 oncoproteins as well as MHC Class I molecules in CaSki and SiHa cell lines when compared with untreated tumor cells. Both cell lines showed increased mRNA expression for MHC Class I molecules in a dose-dependent manner. E6/E7 oncoproteins also were up-regulated in a dose-dependent manner in the CaSki cell line, whereas in the SiHa cell line their expression plateau at 5000 cGy. When the kinetics of radiation-induced up-regulation of E6/E7 were studied, persistent up-regulation of the viral oncoproteins was noted for all doses of irradiation, with the lower and sublethal doses (i.e., 1250-2500 cGy) inducing the most significant enhancement. High doses of irradiation can induce a significant and long-lasting up-regulation of E6/E7 oncogenes and MHC Class I restriction elements on HPV positive cervical carcinoma cell lines. These effects by themselves suggest that irradiation could enhance local tumor immunogenicity in patients receiving radiation therapy. However, in contrast to this possible beneficial effect, sublethal tumor irradiation (up-regulating E6/E7 transforming oncoproteins) also could confer a significant growth advantage to radiation-resistant tumor cells. These findings, combined with the previously reported acquisition of a radiation-induced drug resistance, could provide a biologic basis for the poor prognosis of patients with cervical carcinoma recurrence after radiation therapy.

Third order optical nonlinear properties of gold (Au) nanoparticles synthesized by green laser ablation in bio-based Poly(ε-caprolactone) solution

Two hundred and eighteen female rats were utilized in this study to evaluate the indirect effect of maternal x-irradiation on embryonic development and survival. There were two control groups and ten experimental groups receiving 0, 60, 150, 275, or 400 R on the afternoon of the first day. The use of special shielding devices permitted irradiation of either the mother or the zygote. Several groups of pregnant rats were exposed to 150 R on the afternoon of the first day of gestation. Irradiation of the oviduct and the ova resulted in a 60 to 70% resorption of the implanted ova. Irradiation of the maternal organism while the oviduct was shielded did not increase the resorption rate above control levels. Thus, no indirect effect was demonstrated when the maternal organism received 150 R. When the maternal rats received 400 R and the ova were shielded, 25 % of the implanted embryos resorbed. This was apparently not due to leakage of irradiation around or through the special shielding. Thus, high doses of irradiation in the rat have a moderate indirect effect, but this indirect effect first becomes manifest when the dose of irradiation is above the LD,0 following direct irradiation of the ova. Neither maternal irradiation nor zygote irradiation on the first day of gestation results in an increase in gross congenital malformations or produces fetal growth retardation.

Degradation in Kapton foil after gamma irradiation at low fluence is presented. These foils are irradiated for doses ranging from 10 to 500 kGy. The irradiated (10–50 kGy) Kapton foils show an uniform increase in visible absorption from 500 to 800 nm that decreases for further irradiation up to 500 kGy. FTIR spectra show first decrease in the absorption for all the peaks from 10 to 50 kGy and then increase from 50 to 500 kGy irradiation. Absorption of water moisture has also been observed at low fluence (∼10 kGy) that decreases at higher doses of irradiation. Difference spectra of Kapton before and after irradiation show chain scission at low fluence. This chain scission creates various types of defects, radicals and color centers. The reorganization/cross-linking of bonds is found at higher doses (>50 kGy) of irradiation, where the moisture absorbed at low doses of irradiation plays an important role. The Kapton foil shows opposite nature in terms of chain scission and cross-linking in comparison to the Poly (methyl methacrylate) irradiated in similar conditions.

Effect of gamma-irradiation on (PEO/PVP)/Au nanocomposite: Materials for electrochemical and optical applications

Tumor cells from five freshly isolated ovarian tumors and four established human ovarian carcinoma cell lines were analyzed for the production of the immunoinhibitory cytokine transforming growth factor-beta (TGF-beta) before and after exposure to gamma irradiation and/or the cytokines TNF-alpha plus IFN-gamma. All fresh tumors secreted high levels of TGF-beta when compared to the levels produced by the established ovarian carcinoma cell lines. TGF-beta produced by fresh tumors was significantly reduced after high doses of gamma irradiation (10,000 cGy). In contrast with the established cell lines, irradiation significantly increased TGF-beta secretion. Exposure of fresh tumor cells to cytokines followed by irradiation caused significant reduction of TGF-beta released when compared to the amount released after exposure to cytokines only. However, in the established cell lines, cytokines followed by irradiation again significantly increased TGF-beta production. These data indicate that high doses of irradiation in fresh ovarian tumors, unlike established ovarian carcinoma cell lines, can significantly reduce the local production of this potent immunoinhibitory cytokine. This effect could work to further amplify weak immunological responses within the tumor. In addition, these findings indicate major differences between fresh tumor samples and established cell lines and warn against the sole use of continuous cell lines as models for tumors growing in vivo.

Influence of silica fillers during the electron irradiation of DGEBA/TETA epoxy resins, part II: Study of the thermomechanical properties

The present study focuses on the synthesis of efficient nano photocatalysts (pure and gadolinium‐doped zinc oxide: gold nanocomposites) for the degradation of malachite green dye in polluted water. The synthesis of nanocomposites was achieved by the less time‐consuming sonochemical method under ambient laboratory conditions. The synthesized nanocomposites were characterized by various spectroscopic techniques, namely X‐ray diffraction (for structural and phase analysis), field emission scanning electron microscopy (for morphological studies and average particle size determination), and energy dispersive X‐ray spectroscopy. Optical studies were done with UV–vis absorption spectroscopy and photoluminescence spectroscopy to determine the suitability of nanocomposites as nanophotocatalysts. The synthesized nanocomposites were employed for the degradation of malachite green dye under UV irradiation. The dependence of degradation efficiency on pH, concentration of dye, and nanocomposites was also studied, along with the reusability of nanophotocatalyst. Due to the presence of gadolinium as a dopant and gold nanoparticles, the synthesized ZnO‐based nanocomposites are found to be the most efficient photocatalysts for the degradation of malachite green dye in basic conditions under UV irradiation.

Plasmonic CsPbBr3–Au nanocomposite for excitation wavelength dependent photocatalytic CO2 reduction

In the context of high-energy physics experiments, particle accelerators create a significant dose of radiations, up to 106 Gy for example at the Large Hadron Collider (LHC, Cern). Control detectors, such as scintillators, are affected by these high irradiation levels. The literature mentions that the light yield of organic scintillators dramatically drops when strongly irradiated. However, the tested scintillators can recover some of their light output with time. To the best of our knowledge, only the luminescent properties of plastic scintillators were analyzed under high radiation fluxes. But, plastic scintillators are also able to discriminate fast neutrons from gamma rays. In this work, we characterized neutron/gamma discriminating as well as emissive properties of plastic scintillators after high dose irradiations. Two identical lab-made plastic scintillators containing a polystyrene-based matrix and two fluorophores were analyzed before and after high dose irradiation. Irradiation was performed using a Gamma-Cell 220 Excel with twelve 60Co sources and a 53.7 Gy/min dose rate at isocenter. These two scintillators were irradiated to reach a cumulative dose equal to 104 Gy. In order to measure their neutron/gamma discrimination ability, scintillators were coupled to a Hamamatsu R7724-100 photomultiplier tube and placed in front of a 252Cf source (Activity 580 kBq). The anode signal fed a digitizer. Scintillation pulses were then recorded and post-processed. A charge-comparison method was implemented and FoM was evaluated. Offline treatment allowed the estimation of fast and slow decay times of neutron pulses, as well as their relative intensities. In parallel, characterization of radioluminescence properties of irradiated and non-irradiated samples was performed. Results indicate a strong modification in the neutron/gamma discrimination capability before and after high dose irradiations and a redshift of the radioluminescence spectrum. In fact, a 103 Gy irradiation increases the FoM of both sensors by a factor 2.5 at least. Further, as recovery time passes after a 104 Gy cumulative dose, FoM improves for scintillators and is multiplied by 6 compared to the value at the zero dose. Thanks to evaluated decay times and relative intensities, we could infer that a strong irradiation does not produce a higher yield of triplet excited states but it impacts the slow decay time of the tested scintillator. This leads to a better neutron/gamma discrimination than at the zero dose. These observations lead us to believe that the intrinsic nature of the plastic material is modified under high dose irradiation. In this paper we present the current iteration of this ongoing work. The neutron/gamma discrimination properties are presented for both plastic scintillators and first characterization results are discussed. We show that material modification under high dose irradiation manages to an improvement in neutron/gamma discrimination opening the field to applications of very high dose measurements.

We have examined the effect of high-dose x-ray irradiation on electron transport in stabilized amorphous selenium (a-Se) x-ray photoconductive films (of the type used in x-ray image detectors) by measuring the electron lifetime τe through interrupted-field time-of-flight experiments. X-ray induced effects have been examined through two types of experiments. In recovery experiments, the a-Se was preirradiated with and without an applied field (5 V/μm) during irradiation with sufficient dose (typically ∼20 Gy at 21 °C) to significantly reduce the electron lifetime by ∼50%, and then the recovery of the lifetime was monitored as a function of time at three different temperatures, 10 °C, 21 °C, and 35 °C. The lifetime recovery kinetics was exponential with a relaxation time τr that is thermally activated with an activation energy of 1.66 eV. τr is a few hours at 21 °C and only a few minutes at 35 °C. In experiments examining the irradiation induced effects, the a-Se film was repeatedly exposed to x-ray radiation and the changes in the drift mobility and lifetime were monitored as a function of accumulated dose D. There was no observable change in the drift mobility. At 21 °C, the concentration of x-ray induced deep traps (or capture centers), Nd, increases linearly with D (Nd ∼ D) whereas at 35 °C, the recovery process prevents a linear increase in Nd with D, and Nd saturates. In all cases, even under high dose irradiation (∼50 Gy), the lifetime was recoverable to its original equilibrium (pre-exposure) value within a few relaxation times.

Effect of polyamidoamine dendrimer G3 and G4 on skin permeation of 8-methoxypsoralene—In vivo study

ZnO:Au nanocomposites with high photocatalytic activity prepared by liquid-phase pulsed laser ablation

Impact of Bladder Volume and Uterine and Vaginal Geometric Factors on the Irradiated Dose to the Bladder and Small Intestine in Cervical Cancer Patients Treated With Image Guided Brachytherapy

The objective of this study was to establish the effect of postirradiation melting as a function of irradiation dose on the wear behavior and material characteristics of ultrahigh molecular weight polyethylene. Our hypothesis was that a low dose of irradiation followed by melting would have the same improved wear performance as is found with higher doses of irradiation, but without the disadvantages associated with reduced fracture toughness. The hypothesis was tested by measuring the wear performance (wear track area, incidence of pitting and delamination) in a linear doubly curved-on-flat cyclic test, material behavior (elastic modulus, fracture toughness), and aging response (density changes through the thickness) of the following materials: elevated crosslinked groups--radiated at 25, 65, and 120 kGy, melted, sterilized and aged; a melted group--melted, sterilized, and aged; and a control group--sterilized and aged. Our findings suggest that postirradiation melting, not the irradiation dose, dominates the material property changes and wear response. Melting ensured reduced modulus and therefore decreased contact stresses, superior wear performance, and good resistance to aging, even after low levels of irradiation (25 kGy). The low modulus of the 25 kGy elevated crosslinked group, coupled with increased fracture toughness compared to samples irradiated at higher doses and a resistance to aging not found in the melted group, support our hypothesis. A low dose of irradiation followed by heat treatment has the same beneficial effects in terms of improved wear performance, but without the disadvantages of reduced fracture toughness found with higher doses of irradiation.