Apolipoprotein B carbonyl formation is enhanced by lipid peroxidation during copper-mediated oxidation of human low-density lipoproteins.

To determine whether lipid peroxidation is required for apolipoprotein B (apoB) carbonyl formation of human low-density lipoproteins (LDL) during copper-mediated oxidation, we investigated oxidation of native and probucol-preloaded LDL by measuring thiobarbituric acid-reactive substances (TBARS) and apoB carbonyls. Probucol was used because it is known to inhibit lipid peroxidation, but not protein modification. During copper-mediated oxidation, apoB carbonyls formed in a time-dependent manner; high copper concentrations (> or = 30 microM) resulted in saturation of apoB carbonyl content.

Interactions between vitamin E homologues and ascorbate free radicals in murine skin homogenates irradiated with ultraviolet light.

The mechanism of oxidation of ascorbic acid in mouse skin homogenates by UV light was investigated by measuring ascorbate free radical formation using electron spin resonance signal formation. Addition of vitamin E (alpha-tocopherol or alpha-tocotrienol) had no effect, whereas short-chain homologues (2,5,7,8-tetramethyl-6-hydroxychroman-2-carboxylic acid [Trolox] and 2,2,5,7,8-pentamethyl-6-hydroxychromane [PMC]) accelerated ascorbate oxidation. The similar hydrophilicity of ascorbate, Trolox and PMC increased their interaction, thus rapidly depleting ascorbate.

Ozone depletes tocopherols and tocotrienols topically applied to murine skin.

To evaluate ozone damage to hairless mouse skin, two parameters of oxidative damage, vitamin E depletion and malondialdehyde (MDA) production, were measured in vitamin E-enriched and in control skin from mice exposed to ozone (10 ppm). A 5% vitamin E solution (tocotrienol-rich fraction, TRF) in polyethylene glycol (PEG) was applied to 2 sites on the back of hairless mice, PEG to 2 sites. After 2 h, the sites were washed, one of each pair of sites covered and the mice exposed ozone for 2 h.

Cellular and molecular mechanisms of oxidants and antioxidants.

This report summarizes the major categories of oxidants and antioxidants. The mechanisms for modulating the most potent antioxidant in plasma, vitamin E, are described. The roles of oxidants and antioxidants in the redox-sensitive signal transduction pathway of NF-kappa B are discussed.

In vivo exposure to ozone depletes vitamins C and E and induces lipid peroxidation in epidermal layers of murine skin.

To evaluate skin susceptibility to ozone (O3) and to localize possible oxidative damage within the skin layers, hairless mice were exposed to 10 ppm O3 or air (0 ppm O3) for 2 h. The mice were euthanized, the skin removed and frozen. Three skin layers (upper epidermis, lower epidermis/papillary dermis, and dermis) were separated, antioxidant concentrations (alpha-tocopherol and ascorbic acid) and the lipid peroxidation product malondialdehyde (MDA) measured.

Efficacy of topically applied tocopherols and tocotrienols in protection of murine skin from oxidative damage induced by UV-irradiation.

To assess the efficacy of various forms of vitamin E in protection of skin from UV-light-induced oxidative stress, vitamin E (tocotrienol-rich fraction of palm oil, TRF) was applied to mouse skin and the contents of antioxidants before and after exposure to UV-light were measured. Four polypropylene plastic rings (1 cm2) were glued onto the animals' backs, and 20 microliters 5% TRF in polyethylene glycol-400 (PEG) was applied to the skin circumscribed by two rings and 20 microliters PEG to the other two rings. After 2 h, the skin was washed and half of the sites were exposed to UV-irradiation (2.

Redox regulation of NF-kappa B activation.

Cytosolic reactions of the nuclear factor kappa B/inhibitor (NF-kappaB/IkappaB) complex leading to its activation, NF-kappaB translocation into the nucleus, DNA binding, and transactivation have been described with some degree of clarity, but the upstream processes that stimulate those cytosolic reactions remain obscure. These processes definitely involve multiple protein serine/threonine kinases, as proximal modifiers of IkappaB, as well as the corresponding phosphatases, upstream kinases, and phosphatases, including those acting on tyrosine residues. This complex cascade of phosphorylation and dephosphorylation is modulated by redox reactions of unknown nature in the sense that the oxidant status of the cytosol increases the phosphorylation and degradation of IkappaB.

Kinetic study of cutaneous and subcutaneous distribution following topical application of [7,8-14C]rac-alpha-lipoic acid onto hairless mice.

To diminish oxidative injury, topically applied antioxidants must reach susceptible cells. alpha-Lipoic acid is a potent thiol antioxidant that might be useful for skin protection; therefore, its skin penetration kinetics were assessed. The cutaneous and subcutaneous distributions of [7,8-14C]rac-alpha-lipoic acid were studied in anesthetized hairless mice after application of a 5% solution in propylene glycol for 0.

Phenotypic analysis of mice expressing exclusively apolipoprotein B48 or apolipoprotein B100.

Apolipoprotein (apo)-B is found in two forms in mammals: apo-B100, which is made in the liver and the yolk sac, and apo-B48, a truncated protein made in the intestine. To provide models for understanding the physiologic purpose for the two forms of apo-B, we used targeted mutagenesis of the apo-B gene to generate mice that synthesize exclusively apo-B48 (apo-B48-only mice) and mice that synthesize exclusively apo-B100 (apo-B100-only mice). Both the apo-B48-only mice and apo-B100-only mice developed normally, were healthy, and were fertile.

Simultaneous determination of tissue tocopherols, tocotrienols, ubiquinols, and ubiquinones.

A tissue-specific distribution of the various vitamin E forms, tocotrienols and tocopherols, has been found, suggesting that these forms have unique roles in cellular functions. A sensitive procedure is described for the simultaneous determination of individual tocopherols, tocotrienols, ubiquinols, and ubiquinones using gradient high pressure liquid chromatography (HPLC) and electrochemical detection for vitamin E homologues and ubiquinols, and in-line UV detection for ubiquinones. Using this method, the lipophilic antioxidant complement of a variety of hairless mouse tissues was analyzed.

Efficacy of hypochlorous acid scavengers in the prevention of protein carbonyl formation.

We observed that protein (bovine serum albumin) carbonyl content increases upon hypochlorite oxidation, and this increase is inhibited in a concentration-dependent manner in the presence of hypochlorite scavengers. Based on this observation, we tested whether some known hypochlorite scavengers (lipoic acid, cysteine, and glutathione) and some other antioxidants (uric acid, ascorbic acid, alpha-tocopherol, and probucol) could prevent protein carbonyl formation. N-acetylcysteine, dihydrolipoic acid, cysteine, and glutathione (reduced form, GSH), which otherwise could not be tested in a previously reported 5-thio-2-nitrobenzoic acid test system, were successfully evaluated in our assay.

Vitamin E in humans: demand and delivery.

How much vitamin E is enough? An established use of supplemental vitamin E in humans is in the prevention and therapy of deficiency symptoms. The cause of vitamin E deficiency, characterized by peripheral neuropathy and ataxia, is usually malabsorption-a result of fat malabsorption or genetic abnormalities in lipoprotein metabolism. Genetic abnormalities in the hepatic alpha-tocopherol transfer protein also cause vitamin E deficiency-defects in this protein cause an impairment in plasma vitamin E transport.

The phorbol 12-myristate 13-acetate (PMA)-induced oxidative burst in rat peritoneal neutrophils is increased by a 0.1 mT (60 Hz) magnetic field.

Magnetic fields (MF) may affect biological systems by increasing free radical concentrations. To test this, we have investigated whether low frequency (60 Hz) low intensity (0.1 mT) MF can modulate the phorbol 12-myristate 13- acetate (PMA) induced respiratory burst in primed rat peritoneal neutrophils, followed in real time using the dye 2',7'-dichlorofluorescin (DCFH), which reacts with free radical-derived oxidants such as H2O2 (which is formed from the dismutation of superoxide) to become 2',7'-dichlorofluorecein (DCF), a highly fluorescent compound.

Lipoproteins containing apolipoprotein B isolated from patients with abetalipoproteinemia and homozygous hypobetalipoproteinemia: identification and characterization.

Abetalipoproteinemia (ABL) and homozygous hypobetalipoproteinemia (HBL) are inherited disorders which are classically characterized by progressive retinal and spinocerebellar disease, fat-soluble vitamin deficiency, and absence of apolipoprotein (apo) B from the plasma. Using immunoaffinity chromatography with an anti-apo B antiserum, we isolated apo B-containing lipoprotein (LpB) particles from the plasma of 4 ABL and 2 HBL patients. The LpB particles were characterized and compared with low density lipoprotein (LDL) and LpB isolated from normal plasma.

Vitamin E: beyond antioxidant function.

Vitamin E, a potent peroxyl radical scavenger, is a chain-breaking antioxidant that prevents the propagation of free radical damage in biological membranes. We consider the evidence for potential sites in cellular metabolism and signal transduction where vitamin E may have a structure-specific role in addition to its antioxidant function. The roles of tocopherol-binding proteins in cellular trafficking of vitamin E, especially the incorporation of RRR-alpha-tocopherol into nascent lipoproteins, and the delivery of RRR-alpha-tocopherol to the nucleus are considered.

Exencephaly and hydrocephaly in mice with targeted modification of the apolipoprotein B (Apob) gene.

Apolipoprotein B (apoB) is a key structural component of several lipoproteins. These lipoproteins transport cholesterol, lipids, and vitamin E in the circulation. Humans that produce truncated forms of apoB have low plasma concentrations of apoB, beta-lipoproteins, cholesterol, and often vitamin E.

Human plasma vitamin E kinetics demonstrate rapid recycling of plasma RRR-alpha-tocopherol.

A kinetic model of vitamin E transport in humans is described using data from our studies with deuterium-labeled stereoisomers of alpha-tocopherol (RRR- and SRR-). In normal subjects, both alpha-tocopherols are present at similar concentrations in chylomicrons, but by 24 hr, RRR-alpha-tocopherol is at higher plasma concentrations because RRR-alpha-tocopherol is preferentially incorporated into very low density lipoproteins, which are then secreted into plasma. In three nondiscriminator patients with familial isolated vitamin E deficiency, the fractional disappearance rates (mean +/- SD) of deuterium-labeled RRR- and SRR-alpha-tocopherols in plasma were 1.

beta-Carotene transport in human lipoproteins. Comparisons with a-tocopherol.

The purpose of this study was to investigate the temporal relationships of the transport of beta-carotene in human lipoproteins. We administered 60 mg beta-carotene with breakfast to nine fasting subjects, then blood samples were collected at intervals of up to 75 h, lipoproteins were isolated, and beta-carotene was quantitated. beta-Carotene concentrations in chylomicrons and very low density lipoproteins (VLDL) peaked at 6 and 9 h, respectively.

Discrimination between RRR- and all-racemic-alpha-tocopherols labeled with deuterium by patients with abetalipoproteinemia.

The ability to discriminate between stereoisomers of alpha-tocopherol was studied in five patients with abetalipoproteinemia (ABL) because an impairment in secretion of apolipoprotein B-containing lipoproteins might impede the normally enhanced plasma transport of RRR-alpha-tocopherol. An oral dose containing 3.7 g of each 2R, 4'R,8'R-alpha-[5-C2H3]tocopheryl acetate (d3RRR-alpha-tocopheryl acetate) and 2RS,4'RS,8'RS-alpha-[5,7-(C2H3)2]tocopheryl acetate (d6 all rac-alpha-tocopheryl acetate) was administered, then the labeled and unlabeled alpha-tocopherol contents of plasma and red blood cells from multiple blood samples obtained at selected times up to 72 h following the dose were quantitated.

Efficacy of water-soluble vitamin E in the treatment of vitamin E malabsorption in short-bowel syndrome.

A water-soluble form of vitamin E, tocopheryl succinate polyethylene glycol 1000 (TPGS), was used as an oral vitamin E supplement in a 71-y-old patient with severe fat malabsorption and vitamin E deficiency secondary to short-bowel syndrome. An absorption test with deuterium-labeled TPGS demonstrated that TPGS was absorbed and the released alpha-tocopherol was transported normally in lipoproteins. The disappearance portion of the deuterated alpha-tocopherol curves were parallel to those in control subjects, suggesting normal metabolic turnover of alpha-tocopherol.

Concomitant brainstem axonal dystrophy and necrotizing myopathy in vitamin E-deficient rats.

The purpose of this study was to simultaneously evaluate in rats the effects of vitamin E depletion on tissue alpha-tocopherol (alpha-T) concentrations, electrophysiologic measurements and histopathology. Rats (21-day-old male Wistar) were fed either vitamin E-deficient or supplemented (control) diets (n = 6/group) for 10, 16, and 61 weeks. At these times, electrophysiologic tests (electromyography, spinal and somatosensory evoked potentials, and motor nerve conduction velocity) were performed, the rats were killed and alpha-T concentrations of adipose tissue, sciatic nerve, and cervical and lumbar spinal cord were measured along with histopathologic evaluation of skeletal muscles and the nervous system.