Inhibition of adriamycin-promoted microsomal lipid peroxidation by β-carotene, α-tocopherol and retinol at high and low oxygen partial pressures

AbstractIron-dependent peroxidation of rat liver microsomes, enhanced by adriamycin, was measured in the presence of increasing concentrations of α-tocopherol, β-carotene and retinol at low and high pO2. β-Carotene and α-tocopherol inhibited lipid peroxidation by more than 60% when present at concentrations greater than 50 nmol/mg microsomal protein at both high and low pO2. Retinol inhibited peroxidation by 39% at concentrations greater than 100 nmol/mg microsomal protein. This maximal level of inhibition by retinol was unaltered by pO2. However, β-carotene was more effective than α-tocopherol or retinol at a pO2 of 4 mmHg, whereas α-tocopherol was more effective under aerobic conditions. Since adriamycin-dependent lipid peroxidation is maximal at low pO2, β-carotene may play a role in protecting against this process

Response of the benthic fauna of an urban stream during six years of restoration

Okeover Stream flows through the University of Canterbury campus and has been subject to restoration since 1998. While initially spring-fed, its main source of flow is now aquifer water, which has been used for cooling university buildings. Water quality is generally good, but the low-gradient streambed includes substantial amounts of fine inorganic sediment and organic matter including deciduous tree leaves. Restoration activities include riparian plantings, channel shaping, substratum manipulations and additions, the construction of sediment traps and macrophyte management. Thirty aquatic invertebrate taxa (13-19 per year) have been recorded in annual surveys since 2000. Paracalliope fluviatilis (Amphipoda), Copepoda and Oligochaeta were most abundant in all years, whereas Mollusca and Trichoptera always made up <4 % and <2 % of individuals, respectively. Furthermore, cased caddisflies were found only in the two (of four) downstream reaches, whereas Copepoda were predominantly in the upper two reaches where flow was generally slower. Low annual MCI (69-84) and SQMCI (3.5-4.8) values indicated the fauna comprised mainly species that are tolerant of poor water quality or degraded habitat conditions. Our data indicate that the invertebrate fauna has yet to respond positively to the changes in physical habitat and riparian conditions made along Okeover Stream. The introduction of pulses of poor quality water during heavy rainfalls, high levels of siltation, heavy metals in bed sediments, large accumulations of slowly decomposing leaves and an inadequate source of potential colonists may all contribute to the weak response of the invertebrate fauna to restoration activities

Investigation on the removal of the cavitation erosion risk in a control orifice inside a prototype diesel injector

A CFD investigation is in progress to study the cavitation characteristics and potential erosion risks of a control orifice in a prototype injector. An early design of the orifice resulted in cavitation erosion after endurance testing. A design modification eliminated the erosion and subsequent prototypes were free from damage. Initial results for the two designs using different simulation methods are discussed, along with the effects of different rates of evaporating and condensing mass transfer. Preliminary findings on possible erosion risk indicators comparing the eroding with the non-eroding design are presented

Cavitation erosion risk indicators for a thin gap within a diesel fuel pump

Real industrial examples have been used to evaluate the viability of several cavitation erosion risk indicators (ERIs). Industry standard endurance tests resulted in non-critical cavitation erosion of a shoe and shoe-guide assembly in a high-pressure fuel pump. A design modification was made which eliminated the erosion. Transient CFD simulations of the two designs were run. The distribution and intensity of the resulting ERIs were evaluated against photographic evidence of erosion taken after endurance testing. Details of the component dynamics and the resulting cavitation formation and collapse are presented, along with an analysis of the ERIs for their potential usefulness. Of the 11 ERIs studied, two were found to be particularly good indicators, one of which is newly derived for this research. It is now anticipated that using these ERIs to guide product design and development will save considerable time and cost

Biologically significant scavenging of the myeloperoxidase-derived oxidant hypochlorous acid by ascorbic acid Implications for antioxidant protection in the inflamed rheumatoid joint

AbstractAscorbic acid, at physiological concentrations, can scavenge the myeloperoxidase-derived oxidant hypochlorous acid at rates sufficient to protect α1-antiprotease against inactivation by this molecule. The rapid depletion of ascorbic acid at sites of inflammation, as in the inflamed rheumatoid joint, may therefore facilitate proteolytic damage