Oxidative Assault Research Articles

Outstanding Antibiofilm Features of Quanta-CuO Film on Glass Surface.

Intelligently designed surface nanoarchitecture provides defined control over the behavior of cells and biomolecules at the solid-liquid interface. In this study, CuO quantum dots (quanta-CuO; ∼3-5 nm) were synthesized by a simple, low-temperature solution process and further formulated as paint to construct quanta-CuO thin film on glass. Surface morphological characterizations of the as-coated glass surface reveal a uniform film thickness (∼120 ± 10 nm) with homogeneous distribution of quanta-CuO. The antibiofilm assay showed a very high contact bacteria-killing capacity of as-coated quanta-CuO glass surfaces toward Staphylococcus aureus and Escherichia coli. This efficient antibacterial/antibiofilm activity was ascribed to the intracellular reactive oxygen species (ROS) generated by the quanta-CuO attached to the bacterial cells, which leads to an oxidative assault and finally results in bacterial cell death. Although there is a significant debate regarding the CuO nanostructure's antibacterial mode of action, we propose both contact killing and/or copper ion release killing mechanisms for the antibiofilm activity of quanta-CuO paint. Moreover, synergism of quanta-CuO with conventional antibiotics was also found to further enhance the antibacterial efficacy of commonly used antibiotics. Collectively, this state-of-the-art design of quanta-CuO coated glass can be envisioned as promising candidates for various biomedical and environmental device coatings.

Sexual alteration in antioxidant response and esterase profile in Hyalomma anatolicum anatolicum (Acari: Ixodidae) ticks.

The objective of the study was to reveal physiological link between sex specific engorgement pattern and evading mechanism of ticks against oxidative stress as well as acaricides. Quantitative determination of nitric oxide radical scavenging, superoxide dismutase activity and reduced glutathione (GSH) concentrations in salivary gland and gut extracts of male and female Hyalomma anatolicum anatolicum (Acari: Ixodidae) ticks established significant variation in antioxidant responses between two sexes of the ticks. Higher activity of these antioxidants and GSH depletion in females clearly indicate stronger antioxidant defense in female ticks which is to combat host mediated oxidative assault during feeding for greater engorgement and reproductive stress. The females are also better equipped with the mechanism of acaricide resistance as evidenced by higher expression of esterases than males in unfed whole tick extracts in current study.

Prenatal exposure to cigarette smoke enhances oxidative stress in astrocytes of neonatal rat

Oxidative stress is involved in the pathogenesis of smoking-related disease. Protection of astrocytes from oxidative insult appears essential to maintain brain function. In this study, we have investigated the effect of gestational cigarette exposure on astrocyte survival. Pregnant female were randomly allocated to the control group or to the cigarette smoke group in which they were placed in an exposure chamber and inhale three cigarettes smoke twice a day for a period of 20 days. The control group was kept in the exposure chamber for the same duration, but without exposure to cigarette smoke. Newborn rats from both groups were weighed 24 h after birth and then cerebral hemispheres were collected for astrocyte culture. Incubation of astrocytes isolated from animals exposed to cigarette smoke with 300 μM H2O2 for 1 h induced a significant decrease of the proportion of surviving cells compared to cells isolated form control animals. We have observed that H2O2-treated astroglial cells derived from cigarette smoke exposure showed more reduced superoxide dismutase and catalase activities than H2O2-treated astroglial cells from control animals. In conclusion, this study indicates that astroglial cells derived from newborn rats exposed in utero to cigarette smoke are more vulnerable to oxidative assault than cultured astrocytes obtained from control animals. These results point out the existence of excitotoxic lesions in newborn exposed in utero to cigarette smoke and suggest that despite their high antioxidative activities, astrocytes cannot survive and protect neurons under massive oxidative stress.

Binding of Vitamin E in Model Membranes Studied by Umbrella Sampling Simulations

Alpha tocopherol (αtoc), the form of vitamin E that is retained in the human body, is a lipid-soluble anti-oxidant. Its presumptive role is to protect polyunsaturated fatty acids (PUFA) from oxidation in cell membranes. The global concentration of αtoc in the plasma membrane is low (generally < 1 mol%), so preferential interaction with PUFA-containing phospholipids has been hypothesized to optimize protection of the lipid species most vulnerable to oxidative assault. To test this hypothesis we are investigating the desorption energy of αtoc in model membranes using umbrella sampling molecular dynamics (USMD) simulations. Insight into the flip-flop of αtoc across the membrane will also be obtained from the free energy barrier at the center of the bilayer. USMD simulations of αtoc molecules in membranes composed of 1-stearoyl-2-docosahexaenoylphosphatidylcholine (SDPC, 18:0-22:6PC) and, as a monounsaturated reference, 1-stearoyl-2-oleoylphosphatidylcholine (SOPC, 18:0-18:1PC) are now ongoing. The position of the chromanol group of αtoc in the membrane-normal direction is chosen to be the reaction coordinate. The simulations consist of 45 windows separated by 1 Å and arranged from the center of bilayer all the way to the bulk water, each sampled for 200 ns. Preliminary calculation of the mean force in SDPC shows that the equilibrium position for the chromanol group is around 12 Å from the bilayer center, consistent with our earlier simulations. More accurate calculation of the potential of mean force (PMF) is being performed using the weighted histogram analysis method (WHAM).

Metallothionein, oxidative stress and trace metals in gills and liver of demersal and pelagic fish species from Kuwaits’ marine area

Two fish species yellowfin seabream (Acanthopagrus latus) and tonguesole (Cynoglossus arel) were collected from two locations in Kuwait’s territorial waters in non-reproductive periods and used as bio-indicator organism for the assessment of metals in the marine environment. Species variation in fish was observed; seabream contained high metal content and metallothionein in liver and gill tissues compared to tonguesole, especially from Kuwait Bay area. Oxidative injury was registered in the gills of both species, but in tonguesole liver was also involved. Consequently, antioxidant enzyme catalase was elevated in tonguesole enabling bottom dwelling fish to combat oxidative assault. The study provided information about the current status of metals in marine sediment and levels of metals accumulated in representative species along with oxidative damage in exposed tissues and the range of biomarker protein metallothionein and enzymes of antioxidant defence mechanism enhancing our understanding about the biological response to the existing marine environment in Kuwait.

Preclinical efficacy of Dexmedetomidine on spinal cord injury provoked oxidative renal damage

Purpose: Oxidative renal injury is the mainstay in patients with spinal cord injury (SCI) and it may eventuate to chronic renal failure. In our study, we investigated the potential of α2-adrenoreceptor agonist Dexmedetomidine (Dex) in ameliorating SCI provoked oxidative renal assault. Methods: Complete SCI was generated by surgical transaction of the cord at the T10–12 level. Dex administration (50 mcg/kg, b.wt, intraperitoneally) was initiated 12 h after the surgery for 10 days. Then, blood was collected and kidneys were removed to evaluate the efficacy of Dex on post-SCI renal complications. Results: Dex treatment significantly attenuated elevated serum creatinine and blood urea nitrogen in SCI rats to normalcy. Further in SCI rats elevated level of MDA, protein carbonyl and myeloperoxidase (MPO) were observed and Dex treatment significantly attenuated these toxic manifestations to normalcy. Besides in SCI rats, the antioxidants (SOD, CAT, Gpx and GST and GSH) levels were significantly diminished and Dex treated rats significantly restored the antioxidants level in renal tissue to normalcy. Notably, in our study the protein expression of inflammatory cytokines (TNF-α and IL-6) and cleaved caspase-3 were upregulated in renal tissue of SCI rats. Fascinatingly, Dex treatment downregulated the protein expression of TNF-α, IL-6 and cleaved caspase-3 by anti-inflammatory, antiapoptotic mechanism. Furthermore, SCI rats displayed upregulated protein expression of kidney of SCI rats. Dex treatment diminished the renal apoptosis by downregulating the cleaved caspase-3 expression. Conclusion: Taken together, these results accentuate that Dex may be a beneficial clinical agent to combat post-SCI renal complications.

The variable chemotherapeutic response of Malabaricone-A in leukemic and solid tumor cell lines depends on the degree of redox imbalance

The variable chemotherapeutic response of Malabaricone-A in leukemic and solid tumor cell lines depends on the degree of redox imbalance

Investigation on the Origin of Sperm DNA Fragmentation: Role of Apoptosis, Immaturity and Oxidative Stress.

Sperm DNA fragmentation (sDF) represents a threat to male fertility, human reproduction and the health of the offspring. The causes of sDF are still unclear, even if apoptosis, oxidative assault and defects in chromatin maturation are hypothesized. Using multicolor flow cytometry and sperm sorting, we challenged the three hypothesized mechanisms by simultaneously evaluating sDF and signs of oxidative damage (8-hydroxy, 2'-deoxyguanosine [8-OHdG] and malondialdehyde [MDA]), apoptosis (caspase activity and cleaved poly[ADP-ribose] polymerase [cPARP]) and sperm immaturity (creatine phosphokinase [CK] and excess of residual histones). Active caspases and c-PARP were concomitant with sDF in a high percentage of spermatozoa (82.6% ± 9.1% and 53.5% ± 16.4%, respectively). Excess of residual histones was significantly higher in DNA-fragmented sperm versus sperm without DNA fragmentation (74.8% ± 17.5% and 37.3% ± 16.6%, respectively, p < 0.005), and largely concomitant with active caspases. Conversely, oxidative damage was scarcely concomitant with sDF in the total sperm population, at variance with live sperm, where 8-OHdG and MDA were clearly associated to sDF. In addition, most live cells with active caspase also showed 8-OHdG, suggesting activation of apoptotic pathways in oxidative-injured live cells. This is the first investigation on the origin of sDF directly evaluating the simultaneous presence of the signs of the hypothesized mechanisms with DNA breaks at the single cell level. The results indicate that the main pathway leading to sperm DNA breaks is a process of apoptosis, likely triggered by an impairment of chromatin maturation in the testis and by oxidative stress during the transit in the male genital tract. These findings are highly relevant for clinical studies on the effects of drugs on sDF and oxidative stress in infertile men and for the development of new therapeutic strategies.

African eggplant (Solanum anguivi Lam.) fruit with bioactive polyphenolic compounds exerts in vitro antioxidant properties and inhibits Ca2+-induced mitochondrial swelling

ObjectiveTo evaluate the antioxidant and radical scavenging activities of Solanum anguivi fruit (SAG) and its possible effect on mitochondrial permeability transition pore as well as mitochondrial membrane potential (ΔΨm) isolated from rat liver. MethodsAntioxidant activity of SAG was assayed by using 2,2-diphenyl-1-picrylhydrazyl (DPPH), reducing power, iron chelation and ability to inhibit lipid peroxidation in both liver and brain homogenate of rats. Also, the effect of SAG on mitochondrial membrane potential and mitochondrial swelling were determined. Identification and quantification of bioactive polyphenolics was done by HPLC-DAD. ResultsSAG exhibited potent and concentration dependent free radical-scavenging activity (IC50/DPPH=275.03±7.8 μg/mL). Reductive and iron chelation abilities also increase with increase in SAG concentration. SAG also inhibited peroxidation of cerebral and hepatic lipids subjected to iron oxidative assault. SAG protected against Ca2+ (110 μmol/L)-induced mitochondrial swelling and maintained the ΔΨm. HPLC analysis revealed the presence of gallic acid [(17.54±0.04) mg/g], chlorogenic acid (21.90±0.02 mg/g), caffeic acid (16.64±0.01 mg/g), rutin [(14.71±0.03) mg/g] and quercetin [(7.39±0.05) mg/g]. ConclusionsThese effects could be attributed to the bioactive polyphenolic compounds present in the extract. Our results suggest that SAG extract is a potential source of natural antioxidants that may be used not only in pharmaceutical and food industry but also in the treatment of diseases associated with oxidative stress.

Human Red Blood Cells Alterations in Primary Aldosteronism

Aldosterone (Aldo) effects include NADPH oxidase activation involved in Aldo-related oxidative stress. Red blood cells (RBCs) are particularly sensitive to oxidative assault, and both the formation of high molecular weight aggregates (HMWAs) and the diamide-induced Tyr phosphorylation (Tyr-P) level of membrane band 3 can be used to monitor their redox status. The Aldo-related alterations in erythrocytes were evaluated by comparing in vitro evidence. This was a multicenter comparative study. The study included 12 patients affected by primary aldosteronism (PA) and 6 healthy control subjects (HCs), whose RBCs were compared with those of patients with PA. For in vitro experiments, RBCs from HCs were incubated with increasing Aldo concentrations. The Tyr-P level, band 3 HMWA formation, and autologous IgG binding were evaluated. In patients with PA, both Tyr-P levels and band 3 HMWAs were higher than those in HCs. RBCs from HCs were treated with increasing Aldo concentrations in both platelet-poor plasma (PPP) and charcoal-stripped (CS)-PPP. Results showed that Aldo had dose- and time-dependent effects on band 3 Tyr-P and HMWA formation in CS-PPP more than in PPP. These effects were almost completely prevented by canrenone or cortisol. Aldo-related membrane alterations led to increased autologous IgG binding. Erythrocytes from patients with PA show oxidative-like stress evidenced by increased HMWA content and diamide-induced band 3 Tyr-P level. Aldo effects are mediated by the mineralocorticoid receptor, as suggested by the inhibitory effects of canrenone, an antagonist of Aldo. In CS-PPP, in which Aldo induces remarkable membrane alterations leading to IgG binding, Aldo may be responsible for premature RBC removal from circulation.

Oxidative Insults of 2, 2-dichlorovinyl-dimethyl phosphate (DDVP), an Organophosphate Insecticide in Rats Brain

The oxidative insult of 2, 2-dichlorovinyl-dimethyl phosphate (DDVP) in male rats brain was investigated. Rats were grouped into four: A, B, C and D where A, (the control) received orally 1 mL of distilled water; B, C and D (test groups) received orally 2.5, 5 and 10 mg/kg body weight of DDVP respectively for 28 days. DDVP administration caused significant decrease (P&lt;0.05) in the activities of superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase in the brain. Brain levels of glutathione (GSH), total thiol, vitamins C and E were also significantly reduced (P&lt;0.05), while peroxide glutathione (GSSG) level increased significantly (P&lt;0.05). Brain malonidialdehyde and lipid hydroperoxide also increased significantly (P&lt;0.05) in all DDVP treated groups. The available data from this study revealed that DDVP brings about its toxicity through depletion of the antioxidant systems and thus exposing the cells and cellular macromolecules to oxidative assault by reactive oxygen species generated either from its metabolites or other in vivo means. Â

Antioxidant and phytochemical profile of aqueous and ethanolic extract of Garcinia kola

Garcinia kola is widely consumed habitually and used as traditional remedy for various diseases in Nigeria. However, information with respect to the effect of using different solvents of extraction on its antioxidant properties is scanty. Therefore, the present study investigates the effect of different solvents on the phytochemical constituents and antioxidant properties of G. kola. Phytochemicals measured were the total phenolics, flavonoids and vitamin C content while the antioxidant parameters assessed were the free radical scavenging, Fe (II) - chelating and Fe3+ reducing properties. Finally, the ability of both extracts to offer protective benefits to both hepatic and cerebral tissues placed under oxidative assault induced by FeSO4 and sodium nitroprusside (SNP) was also investigated. The phenolic content of G. kola was estimated to be 45.2 ± 0.9 mg/g and 30.3 ± 0.4 mg/g gallic acid equivalent (GAE) for the ethanolic and aqueous extracts, respectively. Whereas the flavonoid content was estimated to be 29.2 ± 0.2 mg/g and 10.8 ± 0.2 mg/g quercetin equivalent (QE) for the ethanolic and aqueous extracts, respectively. In addition, the vitamin C contents were 21.2 ± 0.4 mg/g and 20.8 ± 0.1 mg/g for the ethanolic and aqueous extract of dried G. kola, respectively. In all the antioxidant indices measured, the ethanolic extract possessed significantly higher properties than the aqueous extract (p < 0.05). In view of all, the use of G. kola for the treatment of cough and liver disorders in folkloric medicines may be related to its phytochemical content. Hence, moderate consumption of the fruit should be encouraged as antioxidant supplement. Key words: Garcinia kola, antioxidant, ethanolic, aqueous and phytochemical.

Malabaricone-A induces a redox imbalance that mediates apoptosis in U937 cell line.

BackgroundThe ‘two-faced’ character of reactive oxygen species (ROS) plays an important role in cancer biology by acting both as secondary messengers in intracellular signaling cascades and sustaining the oncogenic phenotype of cancer cells, while on the other hand, it triggers an oxidative assault that causes a redox imbalance translating into an apoptotic cell death.Principal FindingsUsing a tetrazolium [{3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl}-2H-tetrazolium] based cell viability assay, we evaluated the cytotoxicity of a plant derived diarylnonanoid, malabaricone-A on leukemic cell lines U937 and MOLT-3. This cytotoxicity hinged on its ability to cause a redox imbalance via its ability to increase ROS, measured by flow cytometry using 5-(and-6)-chloromethyl-2′,7′-dichlorodihydrofluorescein diacetate and by decreasing glutathione peroxidase activity. This redox imbalance mediated apoptosis was evident by an increase in cytosolic [Ca2+], externalization of phosphatidyl serine as also depolarization of the mitochondrial membrane potential as measured by flow cytometry. There was concomitant peroxidation of cardiolipin, release of free cytochrome c to cytosol along with activation of caspases 9, 8 and 3. This led to cleavage of the DNA repair enzyme, poly (ADP-ribose) polymerase that caused DNA damage as proved by labeling with 4′,6-diamidino-2-phenylindole (DAPI); furthermore, terminal deoxy ribonucleotide transferase catalysed incorporation of deoxy uridine triphosphate confirmed DNA nicking and was accompanied by arrest of cell cycle progression.ConclusionsTaken together, compounds like MAL-A having pro-oxidant activity mediate their cytotoxicity in leukemic cells via induction of oxidative stress triggering a caspase dependent apoptosis.

Mechanisms of Trypanosoma cruzi persistence in Chagas disease

Trypanosoma cruzi infection leads to development of chronic Chagas disease. In this article, we provide an update on the current knowledge of the mechanisms employed by the parasite to gain entry into the host cells and establish persistent infection despite activation of a potent immune response by the host. Recent studies point to a number of T. cruzi molecules that interact with host cell receptors to promote parasite invasion of the diverse host cells. T. cruzi expresses an antioxidant system and thromboxane A(2) to evade phagosomal oxidative assault and suppress the host's ability to clear parasites. Additional studies suggest that besides cardiac and smooth muscle cells that are the major target of T. cruzi infection, adipocytes and adipose tissue serve as reservoirs from where T. cruzi can recrudesce and cause disease decades later. Further, T. cruzi employs at least four strategies to maintain a symbiotic-like relationship with the host, and ensure consistent supply of nutrients for its own survival and long-term persistence. Ongoing and future research will continue to help refining the models of T. cruzi invasion and persistence in diverse tissues and organs in the host.

γ-Tocotrienol does not substantially protect DS neurons from hydrogen peroxide-induced oxidative injury

BackgroundDown syndrome (DS) neurons are more susceptible to oxidative stress and previous studies have shown that vitamin E was able to reduce oxidative stress and improve DS neurons' viability. Therefore, this study was done to investigate the protective role of γ-tocotrienol (γT3) in DS neurons from hydrogen peroxide (H2O2) -induced oxidative stress. The pro-apoptosis tendency of γT3 was compared to α-tocopherol (αT) in non-stress condition as well.MethodsPrimary culture of DS and euploid neurons were divided into six groups of treatment: control, H2O2, γT3 pre-treatment with H2O2, γT3 only, αT pre-treatment with H2O2 and αT only. The treatments were assessed by MTS assay and apoptosis assay by single-stranded DNA (ssDNA) apoptosis ELISA assay, Hoechst and Neu-N immunofluorescence staining. The cellular uptake of γT3 and αT was determined by HPLC while protein expressions were determined by Western blot. Comparison between groups was made by the Student's t test, one-way ANOVA and Bonferroni adjustment as well as two-way ANOVA for multiple comparisons.ResultsOne day incubation of γT3 was able to reduced apoptosis of DS neurons by 10%, however γT3 was cytotoxic at longer incubation period (14 days) and at concentrations ≥ 100 μM. Pre-treatment of αT and γT3 only attenuate apoptosis and increase cell viability in H2O2-treated DS and euploid neurons by 10% in which the effects were minimal to maintain most of the DS cells' morphology. γT3 act as a free radical scavenger by reducing ROS generated by H2O2. In untreated controls, DS neurons showed lower Bcl-2/Bax ratio and p53 expression compared to normal neurons, while cPKC and PKC-δ expressions were higher in DS neurons. On the other hand, pre-treatment of γT3 in H2O2-treated DS neurons have reduced Bcl-2/Bax ratio, which was not shown in euploid neurons. This suggests that pre-treatment of γT3 did not promote DS cell survival. Meanwhile γT3 and αT treatments without H2O2 as well as pre-treatment of γT3 and αT induced changes in cPKC and PKC-δ expression in DS neurons suggesting interaction of γT3 and αT with PKC activity.ConclusionOur study suggests that γT3 pre-treatment are not sufficient to protect DS neurons from H2O2-induced oxidative assault, instead induced the apoptosis process.

In vitro antioxidant properties of aqueous and ethanolic extracts of walnut (Juglans regia)

Walnut has been reported to exhibit several pharmacological properties and widely used in folkloric medicine for the traditional treatment of ailments. Hence, this study sought to investigate the antioxidant properties of the aqueous and ethanolic extract of walnut seed using several antioxidant parameters. Both extracts were tested for free radical scavenging ability against 2, 2 diphenyl-1-picryl hydrazyl (DPPH) radical, ferric reducing and iron (II) chelating ability. Furthermore, the ability of both extracts to offer protective benefit against lipid peroxidation was assessed. Moreover, the phytochemical constituents (total phenolics, flavonoids and vitamin C) of both extracts were measured. Generally, ethanolic extract was found to exhibit a significantly higher antioxidant activity than do aqueous in all parameters determined. Result showed that both extracts demonstrated potent free radical scavenging and ferric reducing ability and iron chelating activity in vitro. Moreover, both extracts demonstrated potent inhibitory effect on proxidant induced oxidative assault against cerebral and hepatic lipid. The phenolic content of Juglans regia was estimated to be 35.22 ± 0.75 mg/g (GAE) for ethanolic and 20.26 ± 0.55 mg/g (GAE) for aqueous extract whereas the flavonoid content was estimated to be 20.02 ± 0.12 mg/g (QE) for ethanolic and 14.82 ± 0.15 mg/g (QE). In addition, the vitamin C contents were 18.22 mg/g and 10.18 mg/g respectively for ethanolic and aqueous extract of dried J. regia. From the foregoing, the wide usage of walnut seed as remedy for ailment in folk medicine may be due to its high phytochemical constituents and potent antioxidant properties in vitro. Hence, information from this study would provide the underlying mechanisms through which walnut seed exhibit its pharmacological properties which when exploited could be helpful in the management of degenerative diseases. Key words: Phytochemical, oxidative assault, proxidant.

Oh the irony: Iron as a cancer cause or cure?

Iron-oxide nanoparticles facilitate cancer diagnosis through enhanced contrast, selectively enhance tumor cell death with magnetic hyperthermia, and improve drug delivery with magnetic drug targeting. One application that remains largely unexplored is using the iron-oxide nanoparticles themselves to selectively inhibit tumor growth. In this leading opinion paper, we propose that high doses of iron-oxide nanoparticles can be used as a treatment for cancer by generating an oxidative assault against cancer. This proposal may be met with resistance considering the controversy surrounding iron in the field of cancer. Iron generates reactive oxygen species through the Fenton reaction, which may both cause – or cure cancer. Additionally, high demand for iron by cancer cells leads to contradictory therapeutic approaches: iron deprivation or overdose are both potential cancer therapies.

Urinary Biomarkers of Oxidative Status in a Clinical Model of Oxidative Assault

We used doxorubicin-based chemotherapy as a clinical model of oxidative assault in humans. The study recruited newly diagnosed breast cancer patients (n = 23). Urine samples were collected immediately before (T0) and at 1 hour (T1) and 24 hours (T24) after i.v. administration of treatment. Measurements included allantoin and the isoprostanes iPF(2alpha)-III, iPF(2alpha)-VI, and 8,12-iso-iPF(2alpha)-VI along with the prostaglandin 2,3-dinor-iPF(2alpha)-III, a metabolite of iPF(2alpha)-III. All biomarkers were quantified using liquid chromatography-tandem mass spectrometry. In all subjects, the levels of the biomarkers increased at T1: allantoin by 22% (P = 0.06), iPF(2alpha)-III by 62% (P < 0.05), iPF(2alpha)-VI by 41% (P < 0.05), 8,12-iso-iPF(2alpha)-VI by 58% (P < 0.05), and 2,3-dinor-iPF(2alpha)-III by 52% (P < 0.05). At T24, the F2-isoprostanes returned to their baseline levels; the levels of allantoin continued to increase, although the T24-T0 difference was not statistically significant. These results indicate that urinary F2-isoprostanes are valid biomarkers and allantoin is a promising biomarker of oxidative status in humans. The levels of biomarkers change quickly in response to oxidative assault and can be used to monitor oxidative status in humans in response to treatments related either to generation of free radicals (chemotherapy and radiation therapy) or to antioxidants (inborn metabolic diseases and Down syndrome).

Model Studies of Membrane Disruption by Photogenerated Oxidative Assault

We have investigated the response of solid-supported phospholipid bilayers to short doses of photogenerated oxidative stress to characterize physical membrane changes during early phases of membrane oxidation. The low-dose oxidative stress is generated by uniformly exposing the bilayer samples using short-wavelength UV radiation (184-257 nm) for short periods (approximately 3 min) and resulting membrane morphological transformations characterized using a combination of wide-field epifluorescence microscopy and imaging ellipsometry measurements. Our results establish that the early phase of membrane oxidation is characterized by the nucleation and growth of discrete microscopic voids within the bilayer. The locations of the voids are randomly distributed throughout the sample surface, despite the uniform illumination. Over longer time scales, the voids continue to grow after the termination of the UV radiation. We also find that the voids heal as sample temperature is raised and that the supported bilayers consisting of fully saturated lipids are less susceptible to the mild oxidation conditions used, regardless of phase state. Analyzing these results in terms of (1) reactive-oxygen species mediated oxidative attack, (2) in situ generation of membrane oxidation products, and (3) their reequilibration between the membrane and the bulk aqueous phase explains the membrane morphological changes observed and provides insights into membrane perturbations following oxidative assault. Specifically, molecular properties of oxidation products (e.g., intrinsic curvature) account for formation and stabilization of voids within contiguous bilayers, and the long-term structural evolution is consistent with slow kinetics of the desorption of these oxidation products from the bilayer into bulk solution. A corollary benefit from our study is that the thermal properties of voids appear to offer a useful means to measure the thermal expansivity of supported membranes.

Biopreservation of red blood cells – the struggle with hemoglobin oxidation

One of the least recognized causes of cellular damage during ex vivo preservation of red blood cells is oxidative injury to the hemoglobin. The latter has been associated with hemolysis through the release of toxic substances and oxidation of vital cell components. This review delineates some of the major pathways that link hemoglobin oxidation and cellular damage, and summarizes the incidence of red blood cell oxidative injury during hypothermic storage, cryopreservation and desiccation stress. Red blood cell hypothermic storage, despite its success, is not exempt from oxidative injury. Growing evidence portrays a time-dependant oxidative assault including formation of reactive oxygen species, attachment of denatured hemoglobin to membrane phospholipids and the release of hemoglobin-containing membrane microvesicles throughout storage. Similar symptoms have been observed in attempts to stabilize red blood cells in the dried state, in which methemoglobin levels of reconstituted red blood cells reached 50%. Factors affecting the rate of hemoglobin oxidation during red blood cell ex vivo storage include compromised antioxidant activity, high concentrations of glucose in the storage media and the presence of molecular oxygen. Hemoglobin oxidation largely dictates our ability to effectively preserve red blood cells. Understanding its origins along with investigating methods to minimize it can significantly improve the quality of our future blood products.