Alendronate-Modified Nanoceria with Multiantioxidant Enzyme-Mimetic Activity for Reactive Oxygen Species/Reactive Nitrogen Species Scavenging from Cigarette Smoke.

Highly toxic radicals including reactive oxygen species (ROS) and reactive nitrogen species (RNS) in cigarette smoke play an important role in oxidative damage of the lungs, which cannot be efficiently scavenged by current filter techniques. Herein, a novel alendronate-coated nanoceria (CeAL) nanozyme is explored for cigarette filter modification for ROS/RNS scavenging. The CeAL nanozyme with an adjustable oxidation state and high thermal stability exhibits an excellent superoxide dismutase (SOD)-like activity, hydroxyl radical elimination capacity, catalase-mimicking activity, and nitric oxide radical scavenging ability. These synergistic antioxidant abilities make the CeAL nanozyme a lucrative additive for cigarette filters. The filter incorporated with the CeAL nanozyme can efficiently scavenge ROS/RNS in the hot smoke generated by burned commercial cigarettes, resulting in reduction of oxidative stress-induced pulmonary injury and acute inflammation of mice. The developed CeAL nanozyme opens up new opportunities for cigarette filter modification to decrease the toxicity of cigarette smoke and expands the application fields of nanoceria.

Radiation-modifying abilities of Nigella sativa and thymoquinone on radiation-induced nitrosative stress in the brain tissue.

To investigate Nigella sativa oil (NSO) and Thymoquinone (TQ) for their antioxidant effects on the brain tissue of rats exposed to ionizing radiation. Fifty-four male albino Wistar rats, divided into six groups, were designed as group I (normal control group) did not receive NSO, TQ or irradiation; group II (control group of TQ) received dimethyl sulfoxide and sham irradiation; group III (control group of NSO) received saline and sham irradiation; group IV (irradiation plus NSO group) received both 5 Gray of gamma irradiation to total cranium and NSO; group V (irradiation plus TQ group) received both irradiation and TQ; group VI (irradiation alone group) received irradiation plus saline. Alterations in nitric oxide (NO·) and peroxynitrite (ONOO(-)) levels, and nitric oxide synthase (NOS) enzyme activity were measured by biochemical methods in homogenized brain tissue of rats. Levels of NO· and ONOO(-), and enzyme activity of NOS in brain tissue of the rats treated with NSO or TQ were found to be lower than in received IR alone (p<0.002) Nigella sativa oil (NSO) and its active component, TQ, clearly protect brain tissue from radiation-induced nitrosative stress.

Voltammetric investigation of DNA damage induced by nitrofurazone and short-lived nitro-radicals with the use of an electrochemical DNA biosensor.

Electrochemical behavior of nitrofurazone (NFZ) was investigated with the use of cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods. The pH-dependence of NFZ was studied at a glassy carbon electrode (GCE) in ethanol/Britton-Robinson buffer (30:70), and short-lived nitro-radicals were generated by the reduction of NFZ at high pHs (>7.0). In the presence of DNA, the DPV peak current of NFZ decreased and the peak potential shifted negatively, which indicated that there was an electrostatic interaction between NFZ and DNA. An electrochemical dsDNA/GCE biosensor was prepared to study the DNA damage produced in the presence NFZ; this process was followed with the use of the Co(phen)(3)(2+) electroactive probe. Also, the oxidation peaks of guanosine (750 mV) and adenosine (980 mV) indicated that DNA damage was related directly to the nitro-radicals. Experiments demonstrated that DNA damage occurred via two different steps while NFZ was metabolized and nitro-radicals were produced. Novel work with AFM on the NFZ/DNA interaction supported the suggestion that in vivo, the nitro-radicals were more cytotoxic than the NFZ molecules. A linear DPV calibration plot was obtained for NFZ analysis at a modified dsDNA/GCE (concentration range: 2.50 × 10(-6)-3.75 × 10(-5) mol L(-1); limit of detection: 8.0 × 10(-7) mol L(-1)), and NFZ was determined successfully in pharmaceutical samples.

Reactive species and DNA damage in chronic inflammation: reconciling chemical mechanisms and biological fates.

Chronic inflammation has long been recognized as a risk factor for many human cancers. One mechanistic link between inflammation and cancer involves the generation of nitric oxide, superoxide and other reactive oxygen and nitrogen species by macrophages and neutrophils that infiltrate sites of inflammation. Although pathologically high levels of these reactive species cause damage to biological molecules, including DNA, nitric oxide at lower levels plays important physiological roles in cell signaling and apoptosis. This raises the question of inflammation-induced imbalances in physiological and pathological pathways mediated by chemical mediators of inflammation. At pathological levels, the damage sustained by nucleic acids represents the full spectrum of chemistries and likely plays an important role in carcinogenesis. This suggests that DNA damage products could serve as biomarkers of inflammation and oxidative stress in clinically accessible compartments such as blood and urine. However, recent studies of the biotransformation of DNA damage products before excretion point to a weakness in our understanding of the biological fates of the DNA lesions and thus to a limitation in the use of DNA lesions as biomarkers. This review will address these and other issues surrounding inflammation-mediated DNA damage on the road to cancer.

Bystander effect of vinorelbine alters antitumor immune response.

The bystander effect (BE) is the ability of malignant cells affected by an anticancer agent to induce damage in neighboring cancer cells. In this study, we showed that it could also affect immune cells surrounding the tumor and interfere with the antitumor immune response. We observed that the exposure of human lung cancer cells A549 to vinorelbine induced a BE on neighboring human peripheral blood mononuclear cells (PBMCs) in vitro and on mice splenocytes in vivo. In vitro, the number of PBMCs killed because of their coculture with vinorelbine-pretreated A549 cells was 33% higher than those killed by A549 control cells (p = 0.003). In addition, we showed that when vinorelbine-pretreated A549 cells were injected into immunocompetent mice, splenocyte proliferation ex vivo toward tumor cells decreased by 27% compared with that seen in mice injected with untreated A549 cells (p = 0.03). Finally, in vivo experiment in A549 tumor bearing nude mice showed that adoptive transfer of A549 immune splenocytes was not able to delay tumor growth when vinorelbine-pretreated A549 cells were used for immunization. Inhibition of the BE by the nitric oxide synthase inhibitor, N(G)-nitro-L-arginine methyl ester, and the superoxide dismutase mimic, mangafodipir, suggested that it was mediated by oxidative and nitrosative stress. In conclusion, exposure of cancer cells to vinorelbine alters the antitumor immune response through a BE mediated by cellular oxidative and nitrosative stress. Our results offer new prospects for using oxidative stress modulators to restore the antitumor immune response in patients treated with anticancer agents.

Protective effects of polyphenolics in red wine on diabetes associated oxidative/nitrative stress in streptozotocin-diabetic rats.

Increased accumulation of NT (3-nitrotyrosine) and PARylated [poly(ADP-ribosyl)ated] proteins in the tissues of diabetics are associated with diabetes complications (diabetes neuropathy, nephropathy and retinopathy). Red wine (its polyphenols are considered to be the main active components) can act as ROS (reactive oxygen species) scavengers, iron chelators and enzyme modulators. This study is novel in investigating the effect of red wine in preventing the accumulation of NT and PARylated proteins in the sciatic nerve, DRG (dorsal root ganglia), spinal cord, kidney and retina of diabetic animals. We have shown that during the experiment the body weight of control and diabetic groups of rats with consumption of red wine was significantly increased, by 52% and 19% accordingly. The significant increase in the content of NT in the sciatic nerve, DRG, spinal cord, kidney and retina, and PARylated proteins in the sciatic nerve, renal glomeruli and retinae of diabetic rats was partly or completely prevented by treatment with red wine. Red wine and its polyphenol preparations might be a promising option in the prevention and treatment of diabetic complications.

Resveratrol as a therapeutic agent for neurodegenerative diseases.

Excess production of reactive oxygen species in the brain has been implicated as a common underlying risk factor for the pathogenesis of a number of neurodegenerative disorders, including Alzheimer's disease (AD), Parkinson's disease (PD), and stroke. In recent years, there is considerable interest concerning investigation of antioxidative and anti-inflammatory effects of phenolic compounds from different botanical sources. In this review, we first describe oxidative mechanisms associated with stroke, AD, and PD, and subsequently, we place emphasis on recent studies implicating neuroprotective effects of resveratrol, a polyphenolic compound derived from grapes and red wine. These studies show that the beneficial effects of resveratrol are not only limited to its antioxidant and anti-inflammatory action but also include activation of sirtuin 1 (SIRT1) and vitagenes, which can prevent the deleterious effects triggered by oxidative stress. In fact, SIRT1 activation by resveratrol is gaining importance in the development of innovative treatment strategies for stroke and other neurodegenerative disorders. The goal here is to provide a better understanding of the mode of action of resveratrol and its possible use as a potential therapeutic agent to ameliorate stroke damage as well as other age-related neurodegenerative disorders.

Effects of cigarette smoke borne reactive nitrogen species on salivary alpha-amylase activity and protein modifications.

Cigarette smoke (CS) is associated with a variety of human pathologies including cardiovascular disease and cancer. Oral squamous cell carcinoma (OSCC) is the most common malignancy of the head and neck. The major inducer of OSCC is exposure to tobacco. Recent studies demonstrated that oxidative and nitrosative stress contributes to the development of oral carcinogenesis through DNA damage. All salivary reactive nitrogen species (RNS) analyzed from OSCC patients are significantly higher in comparison with healthy subjects. Our findings show that CS and external RNS addition induced reduction in alpha-amylase activity and produced some excited carbonyl formation, but to a much less extant than CS. The addition of epigallocatechine-3-gallate (EGCG) to saliva produced no protective effect against damage to alpha-amylase activity. Our proposed mechanism for the decrease in alpha-amylase activity is the formation of adducts at SH groups of the alpha-amylase active site. In this case, EGCG was unable to counteract this phenomenon, as it does not reduce the concentration of disulfides, and does not alter the amount of protein-SH moieties. However, EGCG did reduce the levels of excited carbonyl formation. Our results indicate that although RNS are abundant in CS, a significant decrease in amylase activity is due to other components in CS, probably aldehydes, reacting with the thiol group of proteins by the Michael addition reaction.

Epidemic inflammation: pondering obesity.

Over the past two decades, inflammation has been recognized as a major driver in the pathogenesis of several common diseases, including atherosclerosis, diabetes, cancer, and asthma. Over the same period, there has been a steep rise in the incidence of obesity, a major risk factor for these disorders. Inflammation of adipose tissue is now recognized to accompany obesity and contribute to its sequelae. Thus, whereas obesity is primarily a disorder of energy balance, it may be helpful to consider it also as a form of epidemic inflammation that predisposes to other forms of epidemic inflammation. It is a fundamental biologic challenge to understand how a positive energy balance and inflammation are linked. This work reviews evidence that reactive oxygen and nitrogen intermediates (ROI and RNI) help drive chronic inflammation in the obese. This is proposed to be a maladaptive instance of our evolved dependence on ROI and RNI for both homeostatic signaling and host defense. ROI and RNI are well suited for these seemingly contradictory dual functions by their metabolic origin, high diffusibility in water and lipid, atomic specificity, and large number of molecular targets. When we eat so much and work so little that we repeatedly generate reactive compounds at levels normally reserved for emergencies, we treat our own cells like invading microbes.

Cigarette smoke induces an unfolded protein response in the human lung: a proteomic approach.

Cigarette smoking, which exposes the lung to high concentrations of reactive oxidant species (ROS) is the major risk factor for chronic obstructive pulmonary disease (COPD). Recent studies indicate that ROS interfere with protein folding in the endoplasmic reticulum and elicit a compensatory response termed the "unfolded protein response" (UPR). The importance of the UPR lies in its ability to alter expression of a variety of genes involved in antioxidant defense, inflammation, energy metabolism, protein synthesis, apoptosis, and cell cycle regulation. The present study used comparative proteomic technology to test the hypothesis that chronic cigarette smoking induces a UPR in the human lung. Studies were performed on lung tissue samples obtained from three groups of human subjects: nonsmokers, chronic cigarette smokers, and ex-smokers. Proteomes of lung samples from chronic cigarette smokers demonstrated 26 differentially expressed proteins (20 were up-regulated, 5 were down-regulated, and 1 was detected only in the smoking group) compared with nonsmokers. Several UPR proteins were up-regulated in smokers compared with nonsmokers and ex-smokers, including the chaperones, glucose-regulated protein 78 (GRP78) and calreticulin; a foldase, protein disulfide isomerase (PDI); and enzymes involved in antioxidant defense. In cultured human airway epithelial cells, GRP78 and the UPR-regulated basic leucine zipper, transcription factors, ATF4 and Nrf2, which enhance expression of important anti-oxidant genes, increased rapidly (< 24 h) with cigarette smoke extract. These data indicate that cigarette smoke induces a UPR response in the human lung that is rapid in onset, concentration dependent, and at least partially reversible with smoking cessation. We speculate that activation of a UPR by cigarette smoke may protect the lung from oxidant injury and the development of COPD.

Salivary uric acid at the acidic pH of the stomach is the principal defense against nitrite-derived reactive species: sparing effects of chlorogenic acid and serum albumin.

A complex antioxidant system is present in human saliva, with uric acid being the most concentrated component. Ascorbic acid, present at low concentrations in saliva, is actively secreted into the gastric lumen. We report that ascorbic acid added to human saliva at pH 2 was consumed within a few minutes, regenerating HNO(2), whereas uric acid was consumed relatively slowly in a nitrite-dependent manner. The consumption of uric acid was (i) rapid under normoxic conditions and slower at low oxygen tensions, (ii) coupled to *NO release, (iii) linked to the decrease in nitrite consumption and in nitrate formation, and (iv) unaffected by the nitrosation catalyst thiocyanate. Both chlorogenic acid and bovine serum albumin, representative of a phenol- and a protein-rich meal, respectively, were able to spare uric acid, although chlorogenic acid increased, whereas bovine serum albumin inhibited, *NO release. We hypothesize that the major role of uric acid in saliva at pH 2 could be to preserve the stomach from the formation of toxic nitrogen species and that low levels of uric acid, together with ascorbic acid consumption, may contribute to the high occurrence of tumors at the gastroesophageal junction and cardia. The sparing effects of dietary compounds may therefore be an important not fully appreciated effect.

Novel aspects of oxidative stress-associated carcinogenesis.

Oxidative stress is associated with carcinogenesis. Reactive oxygen and nitrogen species contribute to the accumulation of mutations in the genome, presumably followed by selective processes. Recent data suggest that preferred signaling pathways exist for oxidative stress-associated carcinogenesis. Whether this completely depends on random mutations induced by reactive species or whether instead some fragile genomic loci are sensitive to oxidative damage in association with changes of transcriptional activity or other topologic or nontopologic effects remains to be explored. Reliable markers for oxidative stress as well as for oxidative stress-induced preneoplastic lesions must be established.

Free radicals, metals and antioxidants in oxidative stress-induced cancer.

Oxygen-free radicals, more generally known as reactive oxygen species (ROS) along with reactive nitrogen species (RNS) are well recognised for playing a dual role as both deleterious and beneficial species. The "two-faced" character of ROS is substantiated by growing body of evidence that ROS within cells act as secondary messengers in intracellular signalling cascades, which induce and maintain the oncogenic phenotype of cancer cells, however, ROS can also induce cellular senescence and apoptosis and can therefore function as anti-tumourigenic species. The cumulative production of ROS/RNS through either endogenous or exogenous insults is termed oxidative stress and is common for many types of cancer cell that are linked with altered redox regulation of cellular signalling pathways. Oxidative stress induces a cellular redox imbalance which has been found to be present in various cancer cells compared with normal cells; the redox imbalance thus may be related to oncogenic stimulation. DNA mutation is a critical step in carcinogenesis and elevated levels of oxidative DNA lesions (8-OH-G) have been noted in various tumours, strongly implicating such damage in the etiology of cancer. It appears that the DNA damage is predominantly linked with the initiation process. This review examines the evidence for involvement of the oxidative stress in the carcinogenesis process. Attention is focused on structural, chemical and biochemical aspects of free radicals, the endogenous and exogenous sources of their generation, the metal (iron, copper, chromium, cobalt, vanadium, cadmium, arsenic, nickel)-mediated formation of free radicals (e.g. Fenton chemistry), the DNA damage (both mitochondrial and nuclear), the damage to lipids and proteins by free radicals, the phenomenon of oxidative stress, cancer and the redox environment of a cell, the mechanisms of carcinogenesis and the role of signalling cascades by ROS; in particular, ROS activation of AP-1 (activator protein) and NF-kappaB (nuclear factor kappa B) signal transduction pathways, which in turn lead to the transcription of genes involved in cell growth regulatory pathways. The role of enzymatic (superoxide dismutase (Cu, Zn-SOD, Mn-SOD), catalase, glutathione peroxidase) and non-enzymatic antioxidants (Vitamin C, Vitamin E, carotenoids, thiol antioxidants (glutathione, thioredoxin and lipoic acid), flavonoids, selenium and others) in the process of carcinogenesis as well as the antioxidant interactions with various regulatory factors, including Ref-1, NF-kappaB, AP-1 are also reviewed.

Emerging concepts in periventricular white matter injury.

Approximately 10% of newborns are born prematurely. Of these children, more than 10% will sustain neurological injuries leading to significant learning disabilities, cerebral palsy, or mental retardation, with very low birth weight infants having an even higher incidence of brain injury. Whereas intraventricular hemorrhage was the most common form of serious neurological injury a decade ago, periventricular white matter injury (PWMI) is now the most common cause of brain injury in preterm infants. The spectrum of chronic PWMI includes focal cystic necrotic lesions (periventricular leukomalacia; PVL) and diffuse myelination disturbances. Recent neuroimaging studies support that the incidence of PVL is declining, whereas diffuse cerebral white matter injury is emerging as the predominant lesion. Factors that predispose to PVL include prematurity, hypoxia, ischemia, and inflammation. It is believed that injury to oligodendrocyte (OL) progenitors contributes to the pathogenesis of myelination disturbances in PWMI by disrupting the maturation of myelin-myelin-forming oligodendrocytes. Other potential mechanisms of injury include activation of microglia and axonal damage. Chemical mediators that may contribute to white matter injury include reactive oxygen (ROS) and nitrogen species (RNS), glutamate, cytokines, and adenosine. As our understanding of the pathogenesis of PWMI improves, it is anticipated that new strategies for directly preventing brain injury in premature infants will evolve.

Nanotransducers in cellular redox signaling: modification of thiols by reactive oxygen and nitrogen species.

The control of signal transduction involves post-translational modification of proteins at key amino acids. Cysteine residues are important in the control of 'redox' cell-signaling pathways, as thiol chemistry offers the possibility of modification by structurally diverse species, including those derived from oxidized lipids, peroxides or nitric oxide. An important and provocative study of the modification of thiols in the transcription factor OxyR recently extended this hypothesis. The findings offer the enticing possibility that the cell can distinguish between different degrees of oxidant and nitrosative exposure by modification at a single site on a signaling molecule.