The marine cytotoxin portimine is a potent and selective inducer of apoptosis.

Portimine is a recently discovered member of a class of marine micro-algal toxins called cyclic imines. In dramatic contrast to related compounds in this toxin class, portimine has very low acute toxicity to mice but is highly cytotoxic to cultured cells. In this study we show that portimine kills human Jurkat T-lymphoma cells and mouse embryonic fibroblasts (MEFs), with LC values of 6 and 2.

Protein thiol oxidation and formation of S-glutathionylated cyclophilin A in cells exposed to chloramines and hypochlorous acid.

Neutrophil oxidants, including the myeloperoxidase products, HOCl and chloramines, have been linked to endothelial dysfunction in inflammatory diseases such as atherosclerosis. As they react preferentially with sulfur centers, thiol proteins are likely to be cellular targets. Our objectives were to establish whether there is selective protein oxidation in vascular endothelial cells treated with HOCl or chloramines, and to identify sensitive proteins.

Roles of superoxide and myeloperoxidase in ascorbate oxidation in stimulated neutrophils and H2O2-treated HL60 cells.

Ascorbate is present at high concentrations in neutrophils and becomes oxidized when the cells are stimulated. We have investigated the mechanism of oxidation by studying cultured HL60 cells and isolated neutrophils. Addition of H(2)O(2) to ascorbate-loaded HL60 cells resulted in substantial oxidation of intracellular ascorbate.

Assessment of redox changes to hydrogen peroxide-sensitive proteins during EGF signaling.

Hydrogen peroxide acts as a second messenger in growth factor signaling where it can oxidize and modify the function of redox-sensitive proteins. While selective thiol oxidation has been measured, there has been no global assessment of protein oxidation following growth factor activation. Significant changes to the abundant and widely distributed redox sensitive thiol proteins were observed in A431 epidermoid carcinoma cells exposed to hydrogen peroxide, but no changes were observed following treatment with epidermal growth factor (EGF).

Proteomic detection of oxidized and reduced thiol proteins in cultured cells.

The oxidation and reduction of cysteine residues is emerging as an important post-translational control of protein function. We describe a method for fluorescent labelling of either reduced or oxidized thiols in combination with two-dimensional sodium dodecyl sulphate polyacrylamide gel electrophoresis (2DE) to detect changes in the redox proteome of cultured cells. Reduced thiols are labelled with the fluorescent compound 5-iodoacetamidofluorescein.

Inhibition of receptor-mediated apoptosis upon Bcl-2 overexpression is not associated with increased antioxidant status.

Bcl-2 is reported to augment the antioxidant capacity of cells and this is hypothesized to contribute to the anti-apoptotic activity of this oncoprotein. We generated a number of stable Jurkat cell lines expressing varying levels of Bcl-2, and showed a strong correlation between Bcl-2 levels and resistance to Fas-mediated apoptosis. While individual differences could be detected, there was no overall correlation between Bcl-2 and the expression and activity of superoxide dismutases, catalase, glutathione peroxidases, thioredoxin, thioredoxin reductases, and peroxiredoxins.

Induction of apoptosis by phenethyl isothiocyanate in cells overexpressing Bcl-XL.

Isothiocyanates are a class of phytochemicals able to induce apoptosis in numerous cells including Jurkat T-lymphoma cells overexpressing the oncoprotein Bcl-2. To test if isothiocyanates are also effective against other anti-apoptotic members of the Bcl-2 family we generated Jurkat cells stably overexpressing Bcl-X(L). Phenethyl isothiocyanate (PEITC) was cytotoxic to these cells, with an LD(50) ranging from 9 to 18 microM depending on the level of Bcl-X(L) expression.

Ascorbate interacts with reduced glutathione to scavenge phenoxyl radicals in HL60 cells.

We have compared the abilities of ascorbate and reduced glutathione (GSH) to act as intracellular free radical scavengers and protect cells against radical-mediated lipid peroxidation. Phenoxyl radicals were generated in HL60 cells, through the action of their myeloperoxidase, by adding H2O2 and phenol. Normally cultured cells, which contain no ascorbate; cells that had been preloaded with ascorbate; and those that had been depleted of GSH with buthionine sulfoximine were investigated.

Prolonged alpha-tocopherol deficiency decreases oxidative stress and unmasks alpha-tocopherol-dependent regulation of mitochondrial function in the brain.

Vitamin E is the major lipid-soluble chain-breaking antioxidant in mammals and plays an important role in normal development and physiology. Deficiency (whether dietary or genetic) results in primarily nervous system pathology, including cerebellar neurodegeneration and progressive ataxia (abnormal gait). However, despite the widely acknowledged antioxidant properties of vitamin E, only a few studies have directly correlated levels of reactive oxygen species with vitamin E availability in animal models.

Long-term vitamin E deficiency in mice decreases superoxide radical production in brain.

We investigated the effect of long-term vitamin E deficiency (38 weeks) on free radical (superoxide) production and free radical products (neuroprostanes and isoprostanes) and on mitochondrial function (oxygraph and electron transport chain activities) in C57B6J mice. We found that after 38 weeks, while liver was approximately 95% deficient, the brain had retained approximately 50% of its alpha-tocopherol. We also found that superoxide production was lowered in multiple brain regions of male vitamin E-deficient mice, as were neuroprostanes.

A comparison of plasma vitamin C and E levels in two Antarctic and two temperate water fish species.

Antarctic fish have a high polyunsaturated lipid content and their muscle cells have a high mitochondria density suggesting that Antarctic fish are under greater oxidative stress than temperate water fish. To test this hypothesis, the plasma concentrations of the antioxidant vitamins E and C were measured in two Antarctic fish species, Pagothenia borchgrevinki and Trematomus bernacchii, and compared with the plasma concentrations of these vitamins in two New Zealand temperate water fish species, blue cod (Parapercis colias) and banded wrasse (Notolabrus fucicola). Neither vitamin is known to be synthesised in fish and so must be obtained from the diet.

Cerebellar vermis diameter at cranial sonography for assessing gestational age in low-birth-weight infants.

Background: Clinical assessment of gestational age for very-low-birth-weight infants is often inaccurate. Survival rates are more dependent on gestational age than on the birth weight.

Objective: To assess whether cerebellar vermis diameter might predict gestational age in infants under 2,000 g and/or under 32 weeks' gestation.

Psychological stress and blood glucose regulation in type I diabetic patients.

Fifteen Type I diabetic patients self-monitored daily mean blood glucose levels (BGL), psychological stress, diet, exercise, and insulin injections for a period of 8 weeks. Separate multiple-regression analyses were conducted for each subject to assess the predictability of BGL from stress reports, independent of the effects of diet, exercise, and insulin self-administration. Considerable individual variability in findings was evident, with stress predicting BGL in a statistically significant manner in 7 of the 15 subjects.