Helen C. Yeo

Immobilization stress causes oxidative damage to lipid, protein, and DNA in the brain of rats.

Immobilization stress of male Spra‐ gue‐Dawley rats induces oxidative damage to lipid, protein, and DNA in the brain. Significant increases in lipid peroxidation were found in the cerebral cortex, cerebellum, hippocampus, and midbrain compared to the unstressed controls. Significant in‐creases in levels of protein oxidation were also found in the cortex, hypothalamus, striatum, and medulla oblongata. Oxidative nuclear DNA damage increased after stress in all brain regions, although only the cerebral cortex showed a significant increase. Depletion of glutathione showed some stimulation to oxidative damage in the unstressed control and stressed animals. Further studies of the mitochondrial and cytosol fractions of cerebral cortex demonstrated that mitochondria showed a significantly greater increase in lipid peroxidation and protein oxidation than cytosol. Data from plasma and liver showed oxidative damage similar to that of the brain. These findings provide evidence to support the idea that stress produces oxidants, and that the oxidative damage in stress could contribute to the degenerative diseases of aging, including brain dysfunction.—Liu, J., Wang, X., Shigenaga, M. K., Yeo, H. C., Mori, A., Ames, B. N. Immobilization stress causes oxidative damage to lipid, protein, and DNA in the brain of rats. FASEB J. 10,1532‐1538 (1996)

ASSAY OF MALONDIALDEHYDE AND OTHER ALKANALS IN BIOLOGICAL FLUIDS BY GAS CHROMATOGRAPHY-MASS SPECTROMETRY

The method described in this chapter allows the accurate measurement of MDA in diverse biological samples and can be extended to measurements of other alkanals. The use of GC/MS-NCI ensures specificity and sensitivity, and the ability to prepare samples without heating limits oxidation artifact. Although the widely used TBA assay for MDA does not require sophisticated equipment, its results may be of limited value as the assay is hindered by the possibility of cross reactivity and by heat-induced oxidation artifact. This GC-MS technique offers the additional advantages of efficient processing of large numbers of samples and the elimination of recovery errors by inclusion of an internal standard.

Chemical comparison of flavours in microwaved and conventionally heated foods

Abstract This paper reviews the chemical differences between the flavour compounds of microwaved and conventionally heated Maillard model systems, meat, baked products and vegetables. Both the food temperature and the length of time the food is heated play important roles in the development of flavour compounds in microwaved systems. Water content also affects the generation of volatile compounds during microwave irradiation; volatiles were produced earlier in cabbage microwaved in the absence of water than in cabbage microwaved in the presence of water. Perceived ‘doneness’ and flavour acceptability are lower in microwaved systems than in conventional systems.