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The present study was designed to determine the radioprotective effects of Malaysian Gelam honey on gene expression and enzyme activity of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) of human diploid fibroblasts (HDFs) subjected to gamma-irradiation. Six groups of HDFs were studied: untreated control, irradiated HDFs, Gelam honey-treated HDFs and HDF treated with Gelam honey pre-, during- and post-irradiation. HDFs were treated with 6 mg/mL of sterilized Gelam honey (w/v) for 24 h and exposed to 1 Gray (Gy) of gamma rays at the dose rate of 0.25 Gy/min. Gamma-irradiation was shown to down-regulate SOD1, SOD2, CAT and GPx1 gene expressions (p < 0.05). Conversely, HDFs treated with Gelam honey alone showed up-regulation of all genes studied. Similarly, SOD, CAT and GPx enzyme activities in HDFs decreased with gamma-irradiation and increased when cells were treated with Gelam honey (p < 0.05). Furthermore, of the three different stages of study treatment, pre-treatment with Gelam honey caused up-regulation of SOD1, SOD2 and CAT genes expression and increased the activity of SOD and CAT. As a conclusion, Gelam honey modulates the expression of antioxidant enzymes at gene and protein levels in irradiated HDFs indicating its potential as a radioprotectant agent.

Electron paramagnetic resonance (EPR) measurements have been carried out on various types of natural fused silica (I301, Q310 and H102) irradiated with gamma-ray doses up to 14 MGy. Paramagnetic defects E′ γ as well as the non-bridging oxygen-hole centre (NBOHC), the peroxide radical (POR) and the aluminium oxygen-hole centre (AlOHC) account for all lines observed in the EPR spectra of irradiated samples. The growth kinetics of AlOHC has been followed and analysed. It is found that AlOHC defects are produced by two processes. One of them, called rapid process, saturates at low doses and has been related to the precursor {AlO 4 − /H + }, H + acting as charge compensator. The second one, called slow process, takes place up to the highest dose and has been related to the precursor {AlO 4 − /M + }, the compensator M + being an alkaline-earth ion Li + , Na + or K + . [ABSTRACT FROM AUTHOR]

The present study was designed to determine the radioprotective effects of Malaysian Gelam honey on gene expression and enzyme activity of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) of human diploid fibroblasts (HDFs) subjected to gamma-irradiation. Six groups of HDFs were studied: untreated control, irradiated HDFs, Gelam honey-treated HDFs and HDF treated with Gelam honey pre-, during- and post-irradiation. HDFs were treated with 6 mg/mL of sterilized Gelam honey (w/v) for 24 h and exposed to 1 Gray (Gy) of gamma rays at the dose rate of 0.25 Gy/min. Gamma-irradiation was shown to down-regulate SOD1, SOD2, CAT and GPx1 gene expressions (p < 0.05). Conversely, HDFs treated with Gelam honey alone showed up-regulation of all genes studied. Similarly, SOD, CAT and GPx enzyme activities in HDFs decreased with gamma-irradiation and increased when cells were treated with Gelam honey (p < 0.05). Furthermore, of the three different stages of study treatment, pre-treatment with Gelam honey caused up-regulation of SOD1, SOD2 and CAT genes expression and increased the activity of SOD and CAT. As a conclusion, Gelam honey modulates the expression of antioxidant enzymes at gene and protein levels in irradiated HDFs indicating its potential as a radioprotectant agent. [ABSTRACT FROM AUTHOR]

Transmission characteristics of gamma-irradiated LiNbO3 waveguides, made by five different methods, are measured and studied. All samples were irradiated with a dosage of 800 krad/h to a total amount of 10 Mrad. With the increasing gamma-irradiation intensity, the annealed proton-exchange waveguide shows the most anti-irradiative ability and the lowest transmission loss, where the measurements were carried out at a wavelength of 633 nm in a harsh gamma-irradiative environment. [ABSTRACT FROM PUBLISHER]