Involvement of vitamin E and protein thiols in the inhibition of microsomal lipid peroxidation by glutathione

Iron-ascorbate stimulated lipid peroxidation in rat liver microsomes can be inhibited by glutathione (GSH). The role of protein thiols and vitamin E in this process was studied in liver microsomes isolated from rats fed diets either sufficient or deficient in vitamin E and incubated at 37°C unde 100% O₂. Lipid peroxidation was induced by adding 400 μM adenosine 5′-triphosphate, 2.5 to 20 μM FeCl₃, and 450 μM ascorbic acid. One mL of the incubation mixture was removed at defined intervals for the measurement of thiobarbituric acid reactive substances (TBARS), protein thiols and vitamin E. In vitamin E sufficient microsomes, the addition of GSH enhanced the lag time prior to the onset of maximal TBARS accumulation and inhibited the loss of vitamin E. Treatment of these microsomes with the protein thiol oxidant diamide resulted in a 56% loss of protein thiols, but did not significantly change vitamin E levels. However, diamide treatment abolished the GSH-mediated protection against TBARS formation and loss of vitamin E during ascorbate-induced peroxidation. Liver microsomes isolated from rats fed a vitamin E deficient diet contained 40-fold less vitamin E and generated levels of TBARS similar to vitamin E sufficient microsomes at a 4-fold lower concentration of iron. GSH did not affect the lag time prior to the onset of maximal TBARS formation in vitamin E deficient microsomes although total TBARS accumulation was inhibited. Similar to what was previously found in vitamin E sufficient microsomes [Palamanda and Kehrer, (1992)Arch. Biochem. Biophys. 293, 103–109], GSH prevented the loss of protein thiols in vitamin E deficient microsomes. However, GSH did not protect efficiently against the loss of residual vitamin E in deficient microsomes. These data provide support for the concept that GSH protects against microsomal lipid peroxidation by maintaining protein thiols, and consequently vitamin E, in the reduced state. The lack of protection in vitamin E deficient microsomes may be related to the inability of such low levels of vitamin E to inhibit peroxidation.     

Ionizing radiation and marketing simulation on bioactive compounds and quality of grapefruit (Citrus paradisi c.v. Rio Red)

Bioactive compounds in citrus fruits have been shown to be protective against chronic diseases such as cancer and heart disease, but their levels may be affected by postharvest treatments such as storage and irradiation. In this study, grapefruits were exposed to gamma irradiation at 0, 150 and 300 Gy and then stored at 10 °C for 36 d, followed by an additional 20 d at 20 °C. Flavonoid content, terpenoid content, quality (acidity and total soluble solids) and phenylalanine ammonia-lyase (PAL) activity were evaluated at regular intervals during storage. Irradiation and storage affected (P ? 0.05) the levels of bioactive compounds in grapefruit; however, the effect of storage was prominent. Irradiation differentially affected the flavonoid content of pulp and peel. Fruits exposed to 300 Gy had higher (P ? 0.01) narirutin content in peel compared to control fruits at 12 and 56 d after storage. While storage increased the d-limonene and myrcene content in all treatments, control fruit had higher terpenoid content at the end of the storage. PAL activity was found to be in traces in the peel. In general, irradiation or storage had no considerable effect on total soluble solids; however, acidity decreased (P ? 0.05) with storage.     

Helping students soar to success on computers: An investigation of the SOAR study method for computer-based learning.

This study used self-report and observation techniques to investigate how students study computer-based materials. In addition, it examined if a study method called SOAR can facilitate computer-based learning. SOAR is an acronym that stands for the method's 4 theoretically driven and empirically supported components: select (S), organize (O), associate (A), and regulate (R). There were 2 experiments. In Experiment 1, 114 undergraduates completed a questionnaire about how they study computer-based materials. Students reported using more ineffective study strategies than effective SOAR strategies. In Experiment 2, 108 different undergraduates read an online text about wildcats and then created materials that reflected their preferred study method, the full SOAR method, or parts of the SOAR method. Specifically, the control group created their preferred study notes; the S group created a complete set of linear notes; the SO group created graphically organized matrix notes; the SOA group created a matrix and associations; and the SOAR group created a matrix, associations, and practice questions that aid self-regulation. The SOAR materials were also created in line with four theoretical principles for technology design (Mayer, 2009). Students studied their materials in preparation for fact and relationship tests. Results from both tests showed that those using the full SOAR method outscored the control group and most other groups using parts of the SOAR method. In addition, observations of students' preferred study methods confirmed the Experiment 1 self-reports that unaided students use ineffective study strategies. Study limitations, suggestions for future research, and instructional implications are presented. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Food systems approach to cancer prevention

New cancer cases are expected to surge 57% worldwide in the next two decades. The greatest burden will be in low- and middle-income countries that are ill equipped to face this epidemic. Similarly, in the United States, low-income populations are at greater risk for cancer. As most cancers contain over 50 genetic alterations, and as these alterations define dysregulation of over 10 different critical cellular signaling pathways, a “silver bullet” treatment is not effective against most cancers. Instead, the latest World Cancer Report (2012) suggests a research shift toward developing prevention strategies for cancer. Accumulating evidence suggests that a diet high in plant-based foods is preventive of a variety of chronic diseases, including cancer. A plethora of bioactive compounds—such as polyphenols, glucosinolates and carotenoids in fruits, vegetables, grains, and legumes—are shown to suppress a variety of biological capabilities required for tumor growth. While much research has shown that plant bioactive compounds can suppress sustained proliferative signaling, angiogenesis, and metastasis, as well as promote cancer stem cell apoptosis, public health campaigns to increase fruit and vegetable consumption have, overall, been less effective than desired. Thus, there is a need for innovative strategies to support increased consumption of bioactive compounds for cancer prevention particularly in vulnerable populations. Many practices of the farm-to-fork continuum, including preharvest practices, postharvest storage, and processing and consumer practices, affect a food's bioactive compound content, composition, and chemopreventive bioactivity. Food system practices may be adjusted to reduce the toxic compound levels (e.g., glycoalkaloids in potatoes) and improve the bioactive compound profile, thus, elevate the cancer fighting properties of fruits, vegetables, and other food products. This review presents current scientific evidence outlining farm-to-fork effects on fruit and vegetable bioactive compounds in order to aid the development of new and reasonable strategies for cancer prevention.     

Photoluminescence and thermoluminescence studies of Tb3+ doped ZnO nanorods

Here in, the synthesis of the terbium doped zinc oxide (ZnO:Tb³⁺) nanorods via room temperature chemical co-precipitation was explored and their structural, photoluminescence (PL) and thermoluminescence (TL) studies were investigated in detail. The present samples were found to have pure hexagonal wurtzite crystal structure. The as obtained samples were broadly composed of nanoflakes while the highly crystalline nanorods have been formed due to low temperature annealing of the as synthesized samples. The diameters of the nanoflakes are found to be in the range 50–60 nm whereas the nanorods have diameter 60–90 nm and length 700–900 nm. FTIR study shows ZnO stretching band at 475 cm^?1 showing improved crystal quality with annealing. The bands at 1545 and 1431 cm^?1 are attributed to asymmetric and symmetric CO stretching vibration modes. The diffuse reflectance spectra show band edge emission near 390 nm and a blue shift of the absorption edge with higher concentration of Tb doping. The PL spectra of the Tb³⁺-doped sample exhibited bright bluish green and green emissions at 490 nm (⁵D₄ → ⁷F₆) and 544 nm (⁵D₄ → ⁷F₅) respectively which is much more intense then the blue (450 nm), bluish green (472 nm) and broad green emission (532 nm) for the undoped sample. An efficient energy transfer process from ZnO host to Tb³⁺ is observed in PL emission and excitation spectra of Tb³⁺-doped ZnO ions. The doped sample exhibits a strong TL glow peak at 255 °C compared to the prominent glow peak at 190 °C for the undoped sample. The higher temperature peaks are found to obey first order kinetics whereas the lower temperature peaks obey 2nd order kinetics. The glow peak at 255 °C for the Tb³⁺ doped sample has an activation energy 0.98 eV and frequency factor 2.77 × 10⁸ s^?1.     

SrWO4: Er3+; an efficient green phosphor for LED and optical thermometry applications

Journal of Materials Science: Materials in Electronics - The present article reports the up- and down-conversion photoluminescence studies of Er3+-activated SrWO4 (SWO) phosphors. The synthesized...     

Extraction of coal using supercritical water

An experimental apparatus was developed to inject coal into an autoclave containing preheated supercritical water. The supercritical water appears to act as both solvent and reactant in the conversion of coal to gases and liquids. Experiments were carried out with German brown coal, lignite and bituminous coal and with glucose at both subcritical and supercritical water densities. A significantly larger quantity of char was obtained when operating at subcritical densities and when the coal was mixed with water before heating to supercritical conditions. Smaller amounts of char were obtained as density increased and as reaction time increased.     

American India Pale Ale matrix rich in xanthohumol is potent in suppressing proliferation and elevating apoptosis of human colon cancer cells

American India Pale Ales (IPAs) with and without addition of dark/roasted malts (DRM) and dry hopping (DP) were analysed to determine whether these processes will increase total phenolic content (TP), antioxidant capacity (AA) and the levels of bioactive compounds (xanthohumol, XN and isoxanthohumol, IX). In addition, bioactivity of whole beer matrices, that is, the ‘phytochemical team approach,’ was compared to isolated compounds, the ‘silver bullet approach,’ by measuring antiproliferative and pro‐apoptotic properties using HCT 116 human colon cancer cells. DP and addition of DRM elevated the XN, IX, TP and AA. Dark malts reduced losses in XN and TP due to filtration. Xanthohumol content positively correlated with phenolic content (r = 0.88, P = 0.0002), indicating that the processes which increased xanthohumol content also elevated other bioactive compounds in beer. However, whole extract from IPAs were more potent in suppressing proliferation and elevating apoptosis in colon cancer cells compared with xanthohumol alone.