Rasha M. Khafagy

Taurine reverses endosulfan-induced oxidative stress and apoptosis in adult rat testis

The present study was aimed to investigate the mechanistic aspect of endosulfan toxicity and its protection by taurine in rat testes. Pre-treatment with taurine (100 mg/kg/day) significantly reversed the decrease in testes weight, and the reduction in sperm count, motility, viability and daily sperm production in endosulfan (5 mg/kg/day)-treated rats. Sperm chromatin integrity and epididymal L-carnitine were markedly decreased by endosulfan treatment. Endosulfan significantly decreased the level of serum testosterone and testicular 3β-HSD, 17β-HSD, G6PDH and LDH-X. Sperm Δψm and mitochondrial cytochrome c content were significantly decreased after endosulfan. Testicular caspases-3, -8 and -9 activities were significantly increased but taurine showed significant protection from endosulfan-induced apoptosis. Oxidative stress was induced by endosulfan treatment as evidenced by increased H2O2 level and LPO and decreased the antioxidant enzymes SOD, CAT and GPx activities and GSH content. These alterations were effectively prevented by taurine pre-treatment. In conclusion, endosulfan decreases rat testes weight, and inhibits spermatogenesis and steroidogenesis. It induces oxidative stress and apoptosis by possible mechanisms of both mitochondria and non-mitochondria pathways. These data provide insight into the mode of action of endosulfan-induced toxicity and the beneficial role provided by taurine to counteract endosulfan-induced oxidative stress and apoptosis in rat testis.

Structure–property behavior of polyethylene exposed to different types of radiation

A detailed study was performed on unirradiated low- and high-density polyethylene (LDPE and HDPE) films as well as irradiated films with different types of radiation such as 60Co γ rays, thermal and fast neutrons, and electron beam irradiation. The structural changes of PE films were characterized by Fourier transform infrared (FTIR), Fourier transform Raman (FT–Raman), and ultraviolet (UV) spectrometric techniques. The results showed significant radiation degradation, crosslinking, and changes in the crystalline and amorphous regions. The influence of γ-radiation on the structure of PE was found to be more prominent compared to that of thermal neutrons and electron beam irradiation. However, LDPE film was found to be more sensitive to these types of radiation in accordance with HDPE because of its lesser degree of crystallinity.

2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-induced cytotoxicity accompanied by oxidative stress in rat Sertoli cells: Possible role of mitochondrial fractions of Sertoli cells

TCDD, as an endocrine disruptor, is known to impair testicular functions and fertility. To elucidate the mechanism(s) underlying the testicular effects of TCDD, the potential toxicity of TCDD on Sertoli cells was investigated. Furthermore, the study aims to delineate whether mitochondrial fractions of Sertoli cells are involved in mediating the testicular effects of TCDD. Adult rat Sertoli cells were incubated with (5, 10 or 15nM) of TCDD for 6, 12 or 24h. Cell viability, lactate and LDH leakage into media along with lipid peroxidation, ROS generation, SOD, CAT, GPx, GR, γ-GT and β-glucuronidase activities, GSH content and Δψ(m) were measured. Superoxide anion production, COX and cardiolipin content were measured in mitochondrial fractions. Cell viability was significantly decreased while lactate and LDH leakage into media were increased. ROS generation along with lipid peroxidation was also increased. SOD, CAT, GPx, GR activities and GSH content were significantly decreased. γ-GT and β-glucuronidase activities were also decreased. Superoxide anion production was increased while COX activity and cardiolipin content were decreased in mitochondrial fractions. Moreover, the Δψ(m) was significantly decreased as measured in Sertoli cells. In conclusion, TCDD impairs Sertoli cell functions and this effect is, at least in part, attributed to oxidative stress. We have also found that TCDD increases mitochondrial superoxide anion production and decreases Δψ(m), COX activity and mitochondrial cardiolipin content. Our findings suggest that mitochondria may play an important role in ROS production, leading to the TCDD-induced oxidative stress response and resulting toxicological consequences in rat Sertoli cells.

Characterization of gamma irradiated polyethylene films by DSC and X‐ray diffraction techniques

The effect of gamma radiation on the thermal behavior and crystalline structure of low density polyethylene (LDPE) has been investigated using differential scanning calorimetry (DSC) and X-ray diffraction techniques (XRD). Gamma irradiation was carried out in atmospheric air to a maximum dose of 883 kGy. DSC results of the heating run from room temperature up to 150 °C showed that the melting temperature (Tm), and onset temperature of LDPE film decrease linearly with increasing irradiation dose. However, upon cooling LDPE film from 150 °C to room temperature, the crystallization temperature (Tc) and onset temperature were found to decrease non-linearly with increasing irradiation dose up to 500 kGy and then tended to level off. The change in heat of fusion (ΔHf) with irradiation dose was found to proceed with different behaviour, two stages, with a kink at irradiation dose of about 500 kGy, being observed. This suggests the occurrence of degradation and crosslinking at low and high doses, respectively. However, parameters of the X-ray diffraction pattern such as number of diffraction patterns, peak position (2θ) and width of the diffraction pattern, support the results of DSC measurements. © 2000 Society of Chemical Industry

Thermal annealing effect on the optical properties of Ag10As30S60 thin film

Chalcogenide Ag10As30S60 thin films are prepared using the thermal evaporation technique from the bulk alloy. Deferential Scanning Calorimetry (DSC) curve reveals two crystallization stages for the bulk. The X-ray examination of the as-prepared and annealed films shows that the sample is crystallized in preferential orientations indicated with peaks corresponding the S8 and ternary AsAg3S3 phases. Transmission spectra show that the as-prepared and annealed films have highly transparent over the visible region. The presence of a sharp absorption edge for all films in the transmission spectra recommends Ag10As30S60 thin films as a good optical filter material. The improvement in transparency upon annealing is due to the enhancement in the crystallinity. The decrease in both optical band gap and refractive index of annealed films after crystallization temperatures is discussed in accordance with the structure changes upon annealing.

Thermally Stimulated Depolarization Current and Thermal Analysis Studies of Gamma Irradiated Lithium‐Salt/Polymer Electrolyte Blends

Thermally stimulated depolarization current (TSDC) and thermal analysis studies of gamma irradiated LiOH/PVA blends were done. To study the mechanisms of conduction and TSDC in poly(vinyl alcohol) (PVA) and LiOH/PVA blends, short circuit TSDC at a polarizing temperature 353 K with a polarizing field of 3 kV cm−1 have been analyzed in the temperature range 300–410 K. Two peaks are evident from the global TSDC measurements on the pure PVA homopolymer. Meanwhile, in all blended samples; there is only one broad peak with a shoulder on the high temperature side due to the relaxation of the poly‐blend system. The temperature dependence, 300–408 K, of the current density (J) for pure PVA and its blended samples has been studied. It was observed that J values increase dramatically with increasing temperature (in the low temperature region from 300–340 K) owing to the formation of local ordered regions in the otherwise disordered amorphous matrix of PVA. Further increase in the temperature caused a marginal increase in J values. The temperature dependence of the specific heat for all samples was measured. A linear increase of C p was observed with an increase in temperature, which is ascribed to the increase in lattice vibration of linear macromolecules and consequently, increases in the number of internal degree of freedom of phonons.

Structural, Vibrational, Thermal And Electrical Characterization Of Gamma Radiation‐Crosslinked Poly (Vinyl Alcohol)‐Based Solid Polymer Electrolytes Blended With LiOH⋅H2O Salt

Solid polymer electrolytes based on poly(vinyl alcohol) (PVA) blended with different concentrations of LiOH⋅H2O salt were prepared using casting and γ‐irradiation techniques. The structure and blending of the poly‐electrolytes were studied by X‐ray diffraction (XRD) and Fourier transform Raman spectroscopy. The thermal properties of these solid polymer electrolytes were examined by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The XRD spectra for the electrolytes indicated that the crystalline ratio of PVA decreases with the concentration of Lithium salt. Crystallinity, isotacticity and syndiotacticity percentages were also determined from Raman spectra at different salt concentrations revealing that the crystallinity and the Isotactic regularity of PVA molecule is reduced with salt addition, while the syndiotacticity increases linearly. DSC thermograms showed good accordance with these facts by detecting two melting temperatures corresponding to the two regularities, and t...