Free Radical Biology and Medicine (v.31, #3)

Acetaminophen (AAP), the analgesic hepatotoxicant, is a powerful inducer of oxidative stress, DNA fragmentation, and apoptosis. The anti-apoptotic oncogene bcl-XL, and the pro-apoptotic oncogene p53 are two key regulators of cell cycle progression and/or apoptosis subsequent to DNA damage in vitro and in vivo. This study investigated the effect of AAP on the expression of these oncogenes and whether agents that modulate DNA fragmentation (chlorpromazine, CPZ) and DNA repair through poly(ADP-Ribose) polymerase (PARP) activity (4-AB: 4-aminobenzamide) can protect against AAP-induced hepatotoxicity by inhibiting oxidative stress, DNA fragmentation, and/or by altering the expression of bcl-XL and p53. In addition, the protective effect of supplemental nicotinamide (NICO), known to be depleted in cells with high PARP activity during DNA repair, is similarly evaluated. Male ICR mice (3 months old) were administered vehicle alone; nontoxic doses of 4-AB (400 mg/kg, ip), NICO (250 mg/kg, ip) or CPZ (25 mg/kg, ip), hepatotoxic dose of AAP alone (500 mg/kg, ip), or AAP plus one of the protective agents 1 h later. All animals were sacrificed 24 h following AAP administration. Serum alanine aminotransferase activity (ALT), hepatic histopathology and lipid peroxidation, DNA damage, and expression of bcl-XL and p53 (western blot analysis) were compared in various groups. All of the three agents significantly prevented AAP-induced liver injury, lipid peroxidation, DNA damage, and associated apoptotic and necrotic cell deaths, 4-AB being the most effective and NICO the least. Compared to control, there was a considerable decrease in bcl-XL expression, and an increase in p53 expression in AAP-exposed livers. The effect of AAP on bcl-XL was antagonized and that on p53 was synergized by the PARP-modulator 4-AB as well as NICO, whereas the endonuclease inhibitor CPZ was without effect on either bcl-XL or p53 expression. These results suggest that the hepatotoxic effect of AAP involves multiple mechanisms including oxidative stress, upregulation of endonuclease (or caspase-activated DNAse) and alteration of pro- and anti-apoptotic oncogenes. The observed antagonism of AAP-induced hepatocellular apoptosis and/or necrosis by modulators of multiple processes including DNA repair suggests the likelihood that a more effective therapy against AAP intoxication should involve a combination of antidotes.
Keywords: Acetaminophen; Apoptosis; bcl-XL; p53; Poly(ADP-ribose)polymerase; Chlorpromazine; 4-Aminobenzamide; Nicotinamide; DNA-repair; Free radicals;

Peroxiredoxins are antioxidant enzymes whose peroxidase activity depends on a redox-sensitive cysteine residue at the active center. In this study we investigated properties of the active center cysteine of bovine 1-Cys peroxiredoxin using a recombinant protein (BRPrx). The only cysteine residue of the BRPrx molecule was oxidized rapidly by an equimolar peroxide or peroxynitrite to the cysteine sulfenic acid. Approximate rates of oxidation of BRPrx by different peroxides were estimated using selenium glutathione peroxidase as a competitor. Oxidation of the active center cysteine of BRPrx by H2O2 proceeded only several times slowly than that of the selenocysteine of glutathione peroxidase. The rate of oxidation varied depending on peroxides tested, with H2O2 being about 7 and 80 times faster than tert-butyl hydroperoxide and cumene hydroperoxide, respectively. Peroxynitrite oxidized BRPrx slower than H2O2 but faster than tert-butyl hydroperoxide. Further oxidation of the cysteine sulfenic acid of BRPrx to higher oxidation states proceeded slowly. Oxidized BRPrx was reduced by dithiothreitol, dihydrolipoic acid, and hydrogen sulfide, and demonstrated peroxidase activity (about 30 nmol/mg/min) with these reductants as electron donors. β-Mercaptoethanol formed a mixed disulfide and did not support peroxidase activity. Oxidized BRPrx did not react with glutathione, cysteine, homocysteine, N-acetyl-cysteine, and mercaptosuccinic acid.
Keywords: Peroxiredoxin; Peroxynitrite; Dihydrolipoic acid; Peroxidase; Sulfenic acid; Cysteine; Eye; Bovine; Free radicals;

Intestinal release and uptake of phenolic antioxidant diferulic acids by Mette F Andreasen; Paul A Kroon; Gary Williamson; Maria-Teresa Garcia-Conesa (304-314).
Diferulic acids are potent antioxidants and are abundant structural components of plant cell walls, especially in cereal brans. As such, they are part of many human and animal diets and may contribute to the beneficial effect of cereal brans on health. However, these phenolics are ester-linked to cell wall polysaccharides and cannot be absorbed in this form. This study provides the first evidence that diferulic acids can be absorbed via the gastrointestinal tract. The 5-5-, 8-O-4-, and 8-5-diferulic acids were identified in the plasma of rats after oral dosing with a mixture of the three acids in oil. Our study also reveals that human and rat colonic microflora contain esterase activity able to release 5-5-, 8-O-4-, and 8-5-diferulic acids from model compounds and dietary cereal brans, hence providing a mechanism for release of dietary diferulates prior to absorption of the free acids. In addition, cell-free extracts from human and rat small intestine mucosa exhibited esterase activity towards diferulate esters. Hence, we have shown that esterified diferulates can be released from cereal brans by intestinal enzymes, and that free diferulic acids can be absorbed and enter the circulatory system. Our results suggest that the phenolic antioxidant diferulic acids are bioavailable.
Keywords: Ferulic acid dehydrodimers; Diferulic acids; Wheat; Rye; Bran; Absorption; Intestinal esterases; Bioavailability; Rat; Human; Free radicals;

Some catecholamines and indolamines inhibit lipid peroxidation. Recent studies indicate that catecholaminergic inhibition of lipid peroxidation may be receptor mediated in vivo and in cell cultures. Because oxidative stress is one of the hypothesized pathogenic mechanisms for neurodegenerative diseases, including Alzheimer’s disease (AD), we hypothesized that catecholaminergic and indolaminergic inhibition of lipid peroxidation would be altered in AD as compared to age-matched non-AD. To test this hypothesis we studied the effect of a variety of neurotransmitters and their antagonists on ascorbate-stimulated lipid peroxidation in membrane fragment preparations derived from postmortem human brain. In this in vitro system, the inhibition of lipid peroxidation by dopamine and serotonin did not appear to be receptor mediated. Further, our findings indicate that there is no apparent effect of age or AD on the inhibition of lipid peroxidation by catecholaminergic and indolaminergic agents.
Keywords: Catecholamines; Serotonin; Lipid peroxidation; Ascorbate; Human brain; Aging; Alzheimer’s disease; Free radicals;

Arsenite induces oxidative DNA adducts and DNA-protein cross-links in mammalian cells by Tsu-Shing Wang; Tsung-Yang Hsu; Chiao-Hui Chung; Alexander S.S Wang; Da-Tian Bau; Kun-Yan Jan (321-330).
Arsenic is generally recognized as a nonmutagenic carcinogen because sodium arsenite induces DNA damage only at very high concentrations. In this study we demonstrate that arsenite concentrations above 0.25 μM induce DNA strand breaks in both human leukemia cells and Chinese hamster ovary cells. Therefore, DNA damage may be involved in arsenic-induced carcinogenesis. Formamidopyrimidine-DNA glycosylase and proteinase K greatly increased DNA strand breaks in arsenite-treated cells, providing evidence that a large portion of arsenite-induced DNA strand breaks come from excision of oxidative DNA adducts and DNA-protein cross-links. Because DNA strand breaks appear only temporarily during excision repair, the level of detectable DNA strand breaks will be low at any given time point. For this reason many previous studies have only detected low levels of DNA strand breaks. We also show that catalase, and inhibitors of calcium, nitric oxide synthase, superoxide dismutase, and myeloperoxidase, could modulate arsenite-induced DNA damage. We conclude that arsenite induces DNA adducts through calcium-mediated production of peroxynitrite, hypochlorous acid, and hydroxyl radicals.
Keywords: Comet assay; Arsenic; DNA damages; DNA-protein cross-links; 8OH-dG; Peroxynitrite; Hypochlorous acid; Hydroxyl radicals; Free radicals;

Reaction conditions affecting the relationship between thiobarbituric acid reactivity and lipid peroxidesin human plasma by Domenico Lapenna; Giuliano Ciofani; Sante D Pierdomenico; Maria Adele Giamberardino; Franco Cuccurullo (331-335).
The thiobarbituric acid (TBA) reactivity of human plasma was studied to evaluate its adequacy in quantifying lipid peroxidation as an index of systemic oxidative stress. Two spectrophotometric TBA tests based on the use of either phosphoric acid (pH 2.0, method A) or trichloroacetic plus hydrochloric acid (pH 0.9, method B) were employed with and without sodium sulfate (SS) to inhibit sialic acid (SA) reactivity with TBA. To correct for background absorption, the absorbance values at 572 nm were subtracted from those at 532 nm, which represent the absorption maximum of the TBA:MDA adduct. Method B gave values of TBA-reactive substances (TBARS) 2-fold higher than those detected with method A. SS lowered TBARS by about 50% with both methods, indicating a significant involvement of SA in plasma TBA reactivity. Standard SA, at a physiologically relevant concentration of 1.5 mM, reacted with TBA, creating interference problems, which were substantially eliminated by SS plus correction for background absorbance. When method B was carried out in the lipid and protein fraction of plasma, SS inhibited by 65% TBARS formation only in the latter. Protein TBARS may be largely ascribed to SA-containing glycoproteins and, to a minor extent, protein-bound MDA. Indeed, EDTA did not affect protein TBARS assessed in the presence of SS. TBA reactivity of whole plasma and of its lipid fraction was instead inhibited by EDTA, suggesting that lipoperoxides (and possibly monofunctional lipoperoxidation aldehydes) are involved as MDA precursors in the TBA test. Pretreatment of plasma with KI, a specific reductant of hydroperoxides, decreased TBARS by about 27%. Moreover, aspirin administration to humans to inhibit prostaglandin endoperoxide generation reduced plasma TBARS by 40%. In conclusion, reaction conditions affect the relationship between TBA reactivity and lipid peroxidation in human plasma. After correction for the interfering effects of SA in the TBA test, 40% of plasma TBARS appears related to in vivo generated prostaglandin endoperoxides and only about 60% to lipoperoxidation products. Thus, the TBA test is not totally specific to oxidant-driven lipid peroxidation in human plasma.
Keywords: Thiobarbituric acid; Malondialdehyde; Alkadienals; Alkenals; Lipoperoxides; Hydroperoxides; Cyclic peroxides; Sialic acid; Plasma; Free radicals;

Measurement of 8-hydroxy-2′-deoxyadenosine in DNA by liquid chromatography/mass spectrometry by Pawel Jaruga; Henry Rodriguez; Miral Dizdaroglu (336-344).
8-Hydroxyadenine (8-OH-Ade) is one of the major lesions, which is formed in DNA by hydroxyl radical attack on the C-8 position of adenine followed by oxidation. We describe the measurement of the nucleoside form of this compound, 8-hydroxy-2′-deoxyadenosine (8-OH-dAdo) in DNA by liquid chromatography/mass spectrometry (LC/MS). The developed methodology enabled the separation by LC of 8-OH-dAdo from intact and modified nucleosides in enzymic hydrolysates of DNA. Measurements by MS were performed using atmospheric pressure ionization-electrospray process. Isotope-dilution MS was applied for quantification using a stable isotope-labeled analog of 8-OH-dAdo. The level of sensitivity of LC/MS with selected-ion monitoring (SIM) for 8-OH-dAdo amounted to approximately 10 femtomol of this compound on the LC column. This level of sensitivity is similar to that previously reported using LC-tandem MS (LC/MS/MS) with multiple-reaction monitoring mode (MRM) (7.5 femtomol). This compound was quantified in DNA at a level of approximately one molecule/106 DNA bases using amounts of DNA as low as 5 μg. The results suggested that this lesion may be quantified in DNA at even lower levels, when more DNA is used for analysis. In addition, gas chromatography/isotope-dilution mass spectrometry with SIM (GC/IDMS-SIM) was applied to measure 8-OH-Ade in DNA following its removal from DNA by acidic hydrolysis. The background levels of 8-OH-dAdo and 8-OH-Ade measured by LC/IDMS-SIM and GC/IDMS-SIM, respectively, were nearly identical. In addition, DNA samples, which were exposed to ionizing radiation at different radiation doses, were analyzed by these techniques. Nearly identical results were obtained, indicating that both LC/IDMS-SIM and GC/IDMS-SIM can provide similar results. The level of sensitivity of GC/MS-SIM for 8-OH-Ade was also measured and found to be significantly greater than that of LC/MS-SIM and the reported sensitivity of LC/MS/MS-MRM for 8-OH-dAdo. The results show that the LC/MS technique is well suited for the measurement of 8-OH-dAdo in DNA.
Keywords: Liquid chromatography/mass spectrometry; Modified nucleosides; Oxidative damage to DNA; Free radicals;

Influence of vitamin E and C supplementation on lipoprotein oxidation in patients with Alzheimer’s disease by Anatol Kontush; Ulrike Mann; Sönke Arlt; Amaar Ujeyl; Charlotte Lührs; Tomas Müller-Thomsen; Ulrike Beisiegel (345-354).
Because increased oxidation is an important feature of Alzheimer’s disease (AD) and low concentrations of antioxidant vitamins C and E have been observed in cerebrospinal fluid (CSF) of AD patients, supplementation with these antioxidants might delay the development of AD. Major targets for oxidation in brain are lipids and lipoproteins. We studied whether supplementation with antioxidative vitamins E and C can increase their concentrations not only in plasma but also in CSF, and as a consequence decrease the susceptibility of lipoproteins to in vitro oxidation. Two groups, each consisting of 10 patients with AD, were for 1 month supplemented daily with either a combination of 400 IU vitamin E and 1000 mg vitamin C, or 400 IU vitamin E alone. We found that supplementation with vitamin E and C significantly increased the concentrations of both vitamins in plasma and CSF. Importantly, the abnormally low concentrations of vitamin C were returned to normal level following treatment. As a consequence, susceptibility of CSF and plasma lipoproteins to in vitro oxidation was significantly decreased. In contrast, the supplementation with vitamin E alone significantly increased its CSF and plasma concentrations, but was unable to decrease the lipoprotein oxidizability. These findings document a superiority of a combined vitamin E + C supplementation over a vitamin E supplementation alone in AD and provide a biochemical basis for its use.
Keywords: Alzheimer’s disease; Oxidation; Vitamin E; Vitamin C; Lipoproteins; Cerebrospinal fluid; Plasma; Antioxidants; Free radicals;

NF-κB, inducible nitric oxide synthase and apoptosis by Helicobacter pylori infection by Joo Weon Lim; Hyeyoung Kim; Kyung Hwan Kim (355-366).
Oxygen radicals are considered as an important regulator in the pathogenesis of Helicobacter pylori (H. pylori)-induced gastric ulceration and carcinogenesis. Inflammatory genes including inducible nitric oxide synthase (iNOS) may be regulated by oxidant-sensitive transcription factor, nuclear factor-κB (NF-κB). iNOS induction has been related to gastric apoptosis. We studied the role of NF-κB on iNOS expression and apoptosis in H. pylori-stimulated gastric epithelial AGS cells. AGS cells were treated with antisense oligonucleotide (AS ODN) for NF-κB subunit p50, an antioxidant enzyme catalase, an inhibitor of NF-κB activation pyrrolidine dithiocarbamate (PDTC), iNOS inhibitors NG-nitro-L-arginine-methyl ester (L-NAME) and 2-amino-5,6-dihydro-6-methyl-4H-1,3-thiazine (AMT), a peroxynitrite donor SIN-1, and a nitric oxide donor NOC-18 in the presence or absence of H. pylori. H. pylori induced cytotocixity time- and dose-dependently, which occurred with induction in iNOS expression and nitrite production. SIN-1 and NOC-18 induced dose-dependent cytotoxicity in AGS cells. Catalase, PDTC, L-NAME, and AMT prevented H. pylori-induced cytotoxicity and apoptosis. It was related to their inhibition on iNOS expression and nitrite production. The cells treated with AS ODN had low levels of p50 and NF-κB and inhibited H. pylori-induced cytotoxicity, apoptosis, iNOS expression, and nitrite production. In conclusion, NF-κB plays a novel role in iNOS expression and apoptosis in H. pylori-infected gastric epithelial cells.
Keywords: Helicobacter pylori; NF-κB; Inducible nitric oxide synthase; Apoptosis; Free radicals;

It has been suggested that oxidative stress plays a major role in various forms of cell death, including necrosis and apoptosis. We have previously reported that fluoride (NaF) induces apoptosis in HL-60 cells by caspase-3 activation. The main focus of this investigation was to arrive at a possible pathway of the apoptosis induced by NaF upstream of caspase-3, because the mechanism is still unknown. The present study showed that after exposure to NaF, there was an increase in MDA and 4-HNE and a loss of mitochondrial membrane potential (δΨm) was also observed in NaF-treated cells.There was a significant increase in cytosolic cytochrome c, which is released from the mitochondria. We have reported a downregulation of Bcl-2 protein in NaF-treated cells. The antioxidants N-acetyl cysteine (NAC), glutathione (GSH) protected the cells from loss of δΨm, and there was no cytochrome c exit or Bcl-2 downregulation, and we suggest that these antioxidants prevent apoptosis induced by NaF. These results suggested that perhaps NaF induced apoptosis by oxidative stress-induced lipid peroxidation, causing loss of δΨm, and thereby releasing cytochrome c into the cytosol and further triggering the caspase cascade leading to apoptotic cell death in HL-60 cells.
Keywords: Apoptosis; Fluoride; Oxidative stress; Lipid peroxides; Cytochrome c; Bcl-2; Free radicals;

Physiological amounts of ascorbate potentiate phorbol ester-induced nuclear-binding of AP-1 transcription factor in cells of macrophagic lineage by Melek C Arkan; Gabriella Leonarduzzi; Fiorella Biasi; Hüveyda Başağa; Giuseppe Poli (374-382).
The aim of the reported research was to assess the potential modulatory effect exerted by physiological amounts of ascorbate complexed or not to iron on activator protein 1 (AP-1) nuclear binding. The metal-vitamin complex was shown able to strongly potentiate AP-1 binding as induced by phorbol 12-myristate 13-acetate (PMA). Such enhancing activity by ascorbate was not observed on PMA-dependent induction of another redox-sensitive transcription factor nuclear factor κB (NF-κB). Experiments performed in the presence of the metal chelator desferrioxamine (DFO) clearly indicated that ascorbate rather than iron was responsible for the potentiation of PMA effect. The composition of AP-1 heterodimers revealed c-Jun, Jun D, and c-Fos as the major subunits upon PMA ± ascorbate stimulation. The change in AP-1 components consequent to such stimuli was mainly dependent upon new synthesis. In fact, protein synthesis inhibitor cycloheximide (CHX) prevented the stimulation of AP-1 nuclear binding due to PMA and ascorbate plus PMA. Further, the vitamin was able to amplify the PMA-dependent induction of p38 and pJNK. Thus, a fine modulation of critical thiols by the vitamin along the MAPK pathway is conceivable.
Keywords: AP-1; NF-κB; Ascorbate; PMA; Oxidative burst; MAPKs; Free radicals;

Protein NMR spin trapping with [methyl-13C3]-MNP: application to the tyrosyl radical of equine myoglobin by Bidisha Bose-Basu; Eugene F DeRose; Yeong-Renn Chen; Ronald P Mason; Robert E London (383-390).
Direct spin trapping studies of protein radical adducts are limited as a consequence of the long rotational correlation times and consequent broadening of the ESR resonances. It can be difficult to determine both the nature and number of adduct species present. NMR detection of reduced spin adducts represents an alternate approach which, however, is subject to the limitations of lower sensitivity and a limited capability for isolating the resonances arising from the reduced adduct from other chemistry involving the spin trap. In the present study, we have utilized [methyl-13C3]-MNP for the detection and analysis of tyrosyl spin adducts formed as a result of exposure of equine myoglobin to hydrogen peroxide. The methyl-13C label allows high detection sensitivity in two dimensions, narrow line widths and most significantly, removal by dialysis of unreacted spin trap as well as any nonprotein derivatives that may form. For equine myoglobin, it is found that adduct formation involves a single residue—Tyr-103 and further that adduct formation occurs at the C-3 carbon of the amino acid. HMQC-NOESY experiments further revealed the proximity of the labeled methyl groups to both the three aromatic tyrosyl protons as well as the aromatic protons of the nearby Phe-106 residue.
Keywords: Myoglobin; Tyrosyl radical; Spin trapping; MNP; NMR; Free radicals;

17β-Estradiol affects in vivo the low density lipoprotein composition, particle size, and oxidizability by José Ignacio Ruiz-Sanz; Rosaura Navarro; Rosa Martı́nez; César Martı́n; Mercedes Lacort; Roberto Matorras; M.Begoña Ruiz-Larrea (391-397).
The aim of this study was to explore the possible modifications induced by 17β-estradiol (E2) in vivo on low-density lipoprotein (LDL) lipid composition, particle size, and oxidizability. For this purpose, women were recruited from an in vitro fertilization program, ranging their plasma E2 levels from less than 12 pg/ml to more than 2000 pg/ml at the end of the treatment. The LDL lipid constituents were analyzed by thin layer chromatography and image analysis, and the LDL diameter was calculated from the lipid data. The results showed that high plasma E2 levels were associated with smaller LDL particles, with lower amounts of free and esterified cholesterol and an increased relative content of α-tocopherol. The hormonal treatment produced a remodelation of the LDL acyl composition, rendering a lipoprotein enriched in saturated fatty acids, with a poorer polyunsaturated fatty acid content. These alterations in the physicochemical properties of LDL paralleled changes in the susceptibility of LDL to in vitro oxidation induced by both Cu2+ and the peroxyl radical generator, 2,2′-azobis (2-amidinopropane), these changes being mainly reflected in a reduced maximum oxidation rate. The in vivo changes in the physicochemical properties of LDL induced by E2 could explain some of the antiatherogenic actions of estrogens.
Keywords: Estrogen; 17β-Estradiol; Low-density lipoprotein; α-Tocopherol; Fatty acid composition; Free radicals;

Carotenoids as scavengers of free radicals in a fenton reaction: antioxidants or pro-oxidants? by Nikolai E. Polyakov; Tatyana V. Leshina; Tatyana A. Konovalova; Lowell D. Kispert (398-404).
The spin trapping EPR technique was used to study the influence of carotenoids (β-carotene, 8′-apo-β-caroten-8′-al, canthaxanthin, and ethyl 8′-apo-β-caroten-8′-oate) on the yield of free radicals in the Fenton reaction (Fe2+ + H2O2 → Fe3+ + •OH + OH) in the organic solvents, DMSO, and methanol. DMPO and PBN were used as spin trapping agents. It was demonstrated that carotenoids could increase or decrease the total yield of free radicals depending on the oxidation potential of the carotenoids and the nature of the radicals. A reaction mechanism is suggested which includes the reduction of Fe3+ to Fe2+ by carotenoids. The effectiveness of this carotenoid-driven Fenton reaction increases with a decrease of the scavenging rates for free radicals and with decreasing oxidation potentials of carotenoids.
Keywords: Carotenoids; Free radicals; Antioxidant activity; Pro-oxidant activity; Fenton reaction; Spin trapping;

Hypothermia enhances bcl-2 expression and protects against oxidative stress-induced cell death in chinese hamster ovary cells by William Slikker; Varsha G Desai; Helen Duhart; Ritchie Feuers; Syed Z Imam (405-411).
Oxidative stress is one of the major causes of cellular injury. Various reactive oxygen (ROS) and nitrogen (RNS) species such as superoxide, hydroxyl radical, peroxynitrite, and nitric oxide are involved in the manifestations of different types of organ toxicity and the resultant syndromes, symptoms, or diseases. Hypothermic conditions have been reported to reduce the oxidative stress in various in vitro and in vivo studies. In the present study, we sought to determine the effect of lowered temperatures on oxidative stress-induced cell death in Chinese hamster ovary (CHO) cells. We also investigated the oxidative stress-induced alterations in the expression of anti-apoptotic protein, bcl-2, in CHO cells at lowered temperatures. CHO cells were incubated at four different temperatures of 30, 32, 35, and 37°C (control temperature) from 1 to 4 d. In another set, the cells were incubated with 100 μM hydrogen peroxide (H2O2) for 30 min before harvesting at different time points. The cells were harvested at 1, 2, 3, and 4 d. Cell survival was significantly higher at 30°C as compared to 37°C over 4 d of incubation. In cells incubated with H2O2, significantly higher cell viability was observed at lower temperatures as compared to the cells incubated at 37°C. The activity of glutathione peroxidase (GSH-Px) also increased significantly at lower temperatures. Lowered temperature also provided a significant increase in the expression of anti-apoptotic protein, bcl-2 after 4 d of incubation. These data suggest that hypothermic conditions lowers the risk of oxidative stress-induced cellular damage and programmed cell death by increasing the activity of GSH-Px and by the induction in the expression of the anti-apoptotic protein, bcl-2.
Keywords: Hypothermia; Oxidative stress; Glutathione peroxidase; Gene expression; Apoptosis; Free radicals;

Iron inhibits the nitric oxide synthesis elicited by asbestos in murine macrophages by Elisabetta Aldieri; Dario Ghigo; Maura Tomatis; Laura Prandi; Ivana Fenoglio; Costanzo Costamagna; Gianpiero Pescarmona; Amalia Bosia; Bice Fubini (412-417).
Crocidolite fibers stimulated nitric oxide synthase (NOS) activity and expression in glial and alveolar murine macrophages: this effect was inhibited by iron supplementation and enhanced by iron chelation. We suggest that in these cells crocidolite stimulates NOS expression by decreasing the iron bioavailability and activating an iron-sensitive transcription factor.
Keywords: Nitric oxide; Asbestos; Crocidolite; Macrophage; Iron; Free radicals;