Hydrogen gas inhalation protects against cutaneous ischaemia/reperfusion injury in a mouse model of pressure ulcer.

Pressure ulcer formation depends on various factors among which repetitive ischaemia/reperfusion(I/R) injury plays a vital role. Molecular hydrogen (H2 ) was reported to have protective effects on I/R injuries of various internal organs. In this study, we investigated the effects of H2 inhalation on pressure ulcer and the underlying mechanisms. H2 inhalation significantly reduced wound area, 8-oxo-dG level (oxidative DNA damage) and cell apoptosis rates in skin lesions. H2 remarkably decreased ROS accumulation and enhanced antioxidant enzymes activities by up-regulating expression of Nrf2 and its downstream components in wound tissue and/or H2 O2 -treated endothelia. Meanwhile, H2 inhibited the overexpression of MCP-1, E-selectin, P-selectin and ICAM-1 in oxidant-induced endothelia and reduced inflammatory cells infiltration and proinflammatory cytokines (TNF-α, IL-1, IL-6 and IL-8) production in the wound. Furthermore, H2 promoted the expression of pro-healing factors (IL-22, TGF-ß, VEGF and IGF1) and inhibited the production of MMP9 in wound tissue in parallel with acceleration of cutaneous collagen synthesis. Taken together, these data indicated that H2 inhalation suppressed the formation of pressure ulcer in a mouse model. Molecular hydrogen has potentials as a novel and alternative therapy for severe pressure ulcer. The therapeutic effects of molecular hydrogen might be related to its antioxidant, anti-inflammatory, pro-healing actions.

Novel findings of secreted cyclophilin A in diabetic nephropathy and its association with renal protection of dipeptidyl peptidase 4 inhibitor.

BACKGROUND: Our previous clinical indicated that urinary cyclophilin A was a good marker for diabetic nephropathy. METHODS: We used animal and cell models of diabetic nephropathy to examine the role of cyclophilin A in disease progression. RESULTS: Significantly increased urinary cyclophilin A could be detected in db/db at the 8th week. Linagliptin (3mg/kg/day and 15mg/kg/day) could suppress urinary 8-hydroxy-2'-deoxyguanosine at the 8th and 16th week but only the high dose Linagliption could suppress cyclophilin A at the 8th week. Compared to 8-hydroxy-2'-deoxyguanosine, cyclophilin A was a stronger, earlier, and more sensitive marker. Immunohistochemical staining for cyclophilin A was also positive for db/db. In cell studies, oxidative stress and hyperglycemia could stimulate MES-13 and HK-2 cells to secrete cyclophilin A. Hyperglycemia stimulated HK-2 cells to secrete TGFß1, which caused secretion of cyclophilin A. The secreted cyclophilin A further stimulated CD 147 to move outward from cytosol onto cell membrane in confocal microscopy, which was associated with the p38 MAPK pathway in the downstream. CONCLUSIONS: Secreted cyclophilin A may play an important role in diabetic nephropathy in the mouse model and is associated with TGFß1, CD 147, and the p38 MAPK pathway.

A mushroom-derived amino acid, ergothioneine, is a potential inhibitor of inflammation-related DNA halogenation.

Myeloperoxidase (MPO)-generated halogenating molecules, such as hypochlorous acid and hypobromous acid (HOBr), in inflammatory regions are postulated to contribute to disease progression. In this study, we showed that ergothioneine (EGT), derived from an edible mushroom, inhibited MPO activity as well as the formation of 8-bromo-2'-deoxyguanosine in vitro. The HOBr scavenging effect of EGT is higher than those of ascorbic acid and glutathione. We initially observed that the administration of Coprinus comatus, an edible mushroom containing a high amount of EGT, inhibited the UV-B-induced inflammatory responses and DNA halogenation, suggesting that EGT is a promising anti-inflammatory agent from mushrooms.

Molecular hydrogen attenuates neuropathic pain in mice.

Neuropathic pain remains intractable and the development of new therapeutic strategies are urgently required. Accumulating evidence indicates that overproduction of oxidative stress is a key event in the pathogenesis of neuropathic pain. However, repeated intra-peritoneal or intrathecal injections of antioxidants are unsuitable for continuous use in therapy. Here we show a novel therapeutic method against neuropathic pain: drinking water containing molecular hydrogen (H2) as antioxidant. The effect of hydrogen on neuropathic pain was investigated using a partial sciatic nerve ligation model in mice. As indicators of neuropathic pain, temporal aspects of mechanical allodynia and thermal hyperalgesia were analysed for 3 weeks after ligation. Mechanical allodynia and thermal hyperalgesia were measured using the von Frey test and the plantar test, respectively. When mice were allowed to drink water containing hydrogen at a saturated level ad libitum after ligation, both allodynia and hyperalgesia were alleviated. These symptoms were also alleviated when hydrogen was administered only for the induction phase (from day 0 to 4 after ligation). When hydrogen was administered only for the maintenance phase (from day 4 to 21 after ligation), hyperalgesia but not allodynia was alleviated. Immunohistochemical staining for the oxidative stress marker, 4-hydroxy-2-nonenal and 8-hydroxydeoxyguanosine, showed that hydrogen administration suppressed oxidative stress induced by ligation in the spinal cord and the dorsal root ganglion. In conclusion, oral administration of hydrogen water may be useful for alleviating neuropathic pain in a clinical setting.

Silibinin attenuates sulfur mustard analog-induced skin injury by targeting multiple pathways connecting oxidative stress and inflammation.

Chemical warfare agent sulfur mustard (HD) inflicts delayed blistering and incapacitating skin injuries. To identify effective countermeasures against HD-induced skin injuries, efficacy studies were carried out employing HD analog 2-chloroethyl ethyl sulfide (CEES)-induced injury biomarkers in skin cells and SKH-1 hairless mouse skin. The data demonstrate strong therapeutic efficacy of silibinin, a natural flavanone, in attenuating CEES-induced skin injury and oxidative stress. In skin cells, silibinin (10 µM) treatment 30 min after 0.35/0.5 mM CEES exposure caused a significant (p<0.05) reversal in CEES-induced decrease in cell viability, apoptotic and necrotic cell death, DNA damage, and an increase in oxidative stress. Silibinin (1 mg) applied topically to mouse skin 30 min post-CEES exposure (2 mg), was effective in reversing CEES-induced increases in skin bi-fold (62%) and epidermal thickness (85%), apoptotic cell death (70%), myeloperoxidase activity (complete reversal), induction of iNOS, COX-2, and MMP-9 protein levels (>90%), and activation of transcription factors NF-κB and AP-1 (complete reversal). Similarly, silibinin treatment was also effective in attenuating CEES-induced oxidative stress measured by 4-hydroxynonenal and 5,5-dimethyl-2-(8-octanoic acid)-1-pyrolline N-oxide protein adduct formation, and 8-oxo-2-deoxyguanosine levels. Since our previous studies implicated oxidative stress, in part, in CEES-induced toxic responses, the reversal of CEES-induced oxidative stress and other toxic effects by silibinin in this study indicate its pleiotropic therapeutic efficacy. Together, these findings support further optimization of silibinin in HD skin toxicity model to develop a novel effective therapy for skin injuries by vesicants.

Selenium compound protects corneal epithelium against oxidative stress.

The ocular surface is strongly affected by oxidative stress, and anti-oxidative systems are maintained in corneal epithelial cells and tear fluid. Dry eye is recognized as an oxidative stress-induced disease. Selenium compound eye drops are expected to be a candidate for the treatment of dry eye. We estimated the efficacy of several selenium compounds in the treatment of dry eye using a dry eye rat model. All of the studied selenium compounds were uptaken into corneal epithelial cells in vitro. However, when the selenium compounds were administered as eye drops in the dry eye rat model, most of the selenium compounds did not show effectiveness except for Se-lactoferrin. Se-lactoferrin is a lactoferrin that we prepared that binds selenium instead of iron. Se-lactoferrin eye drops suppressed the up-regulated expression of heme oxygenase-1, cyclooxygenase-2, matrix metallopeptidase-9, and interleukin-6 and also suppressed 8-OHdG production in the cornea induced by surgical removal of the lacrimal glands. Compared with Se-lactoferrin, apolactoferrin eye drops weakly improved dry eye in high dose. The effect of Se-lactoferrin eye drops on dry eye is possibly due to the effect of selenium and also the effect of apolactoferrin. Se-lactoferrin is a candidate for the treatment of dry eye via regulation of oxidative stress in the corneal epithelium.

Prevention of bleomycin-induced lung fibrosis in mice by a novel approach of parallel inhibition of cyclooxygenase and nitric-oxide donation using NCX 466, a prototype cyclooxygenase inhibitor and nitric-oxide donor.

Cyclooxygenase (COX)-inhibiting nitric oxide (NO) donors (CINODs) are designed to inhibit COX-1 and COX-2 while releasing NO. COX inhibition is responsible for anti-inflammatory and pain-relieving effects, whereas NO donation can improve microcirculation and exert anti-inflammatory and antioxidant actions. In an in vivo mouse model of bleomycin-induced lung fibrosis, we evaluated whether a prototype CINOD compound, (S)-(5S)-5,6-bis(nitrooxy)hexyl)2-(6-methoxynaphthalen-2-yl)propanoate (NCX 466), may show an advantage over naproxen, its congener drug not releasing NO. Bleomycin (0.05 IU) was instilled intratracheally to C57BL/6 mice, which were then treated orally with vehicle, NCX 466 (1.9 or 19 mg/kg), or an equimolar dose of naproxen (1 or 10 mg/kg) once daily for 14 days. Afterward, airway resistance, assumed as lung stiffness index, was assayed, and lung specimens were collected for analysis of lung inflammation and fibrosis. NCX 466 and naproxen dose-dependently prevented bleomycin-induced airway stiffness and collagen accumulation. NCX 466, at the highest dose, was significantly more effective than naproxen in reducing the levels of the profibrotic cytokine transforming growth factor-ß and the oxidative stress markers thiobarbituric acid reactive substance and 8-hydroxy-2'-deoxyguanosine. NCX 466 also decreased myeloperoxidase activity, a leukocyte recruitment index, to a greater extent than naproxen. A similar inhibition of prostaglandin E2 was achieved by both compounds. In conclusion, NCX 466 has shown a significantly higher efficacy than naproxen in reducing lung inflammation and preventing collagen accumulation. These findings suggest that COX inhibition along with NO donation may possess a therapeutic potential in lung inflammatory diseases with fibrotic outcome.

Biphasic effects of free radical scavengers against bleomycin-induced pulmonary fibrosis.

Oxidative stress plays a critical role in the development of pulmonary fibrosis. However, the effects of treatment with anti-oxidant agents against pulmonary fibrosis have not yet been thoroughly investigated. In this study, the effect of MCI-186, a novel free radical scavenger, on bleomycin-induced pulmonary fibrosis was investigated. Bleomycin (0.05units/mouse) was administered intratracheally into C57Bl/6 mice. MCI-186 was given to bleomycin-treated mice intraperitoneally from (i) day -3 to day 7, or from (ii) day 10 to day 28 after bleomycin administration in successive days. At 28 days after bleomycin administration, pulmonary fibrosis was then assessed by lung histology and hydroxyproline. MCI-186 inhibited H(2)O(2)-induced DNA damage in bronchial epithelium in vitro. MCI-186 decreased the lipid peroxide content, a marker for DNA damage, in the lung and reduced 8-OHdG positive cells in the lung in vivo. During the early period (day -3 to day 7) administration, MCI-186 partially attenuated bleomycin-induced pulmonary fibrosis. However, during the late period (day 10 to day 28) MCI-186 exacerbated pulmonary fibrosis, based on the histology and hydroxyproline content. In this condition, MCI-186 in the late period decreased the number of apoptosis cells induced by bleomycin, and therefore it might contribute to the deterioration of pulmonary fibrosis. These data indicate that MCI-186, radical scavenger, has a biphasic effect on bleomycin-induced pulmonary fibrosis in mice. Careful attention should be paid before clinical application of new remedies for pulmonary fibrosis.

alpha-tocopherol supplementation reduces the elevated 8-hydroxy-2-deoxyguanosine blood levels induced by training in basketball players.

BACKGROUND: The aim of the present study was to investigate the effect of alpha-tocopherol (alpha-Te) supplementation on DNA oxidative damage induced by heavy training in basketball players. METHODS: Blood was obtained from 10 players before (group A) and after training (group B) and after 1 month on alpha-Te (200 mg/day, orally) supplementation, before (group C) and after training (group D). Total antioxidant status (TAS), muscle enzyme activities and the biomarker of DNA oxidation, 8-hydroxy-2-deoxyguanosine (8-OHdG), were measured using commercial kits. alpha-Te and catecholamine blood levels were determined using HPLC methods. RESULTS: TAS was higher in the groups with alpha-Te (groups C and D). Levels of 8-OHdG and muscle creatine kinase (CK) and lactate dehydrogenase (LDH) were remarkably lower (0.20+/-0.03 ng/mL, 120+/-15 U/L and 430+/-90 U/L, respectively) in the group with alpha-Te (group D) than in group B (0.42+/-0.05 ng/mL, 286+/-12 U/L and 688+/-88 U/L, respectively; p<0.001). 8-OHdG levels were negatively correlated to TAS and positively to CK levels. CONCLUSIONS: alpha-Te supplementation may reduce DNA oxidation induced by training by protecting muscle cell "death" from glutamate entry and/or by elevation of TAS via amelioration of lipid peroxidation.

Creatine in Huntington disease is safe, tolerable, bioavailable in brain and reduces serum 8OH2'dG.

In a randomized, double-blind, placebo-controlled study in 64 subjects with Huntington disease (HD), 8 g/day of creatine administered for 16 weeks was well tolerated and safe. Serum and brain creatine concentrations increased in the creatine-treated group and returned to baseline after washout. Serum 8-hydroxy-2'-deoxyguanosine (8OH2'dG) levels, an indicator of oxidative injury to DNA, were markedly elevated in HD and reduced by creatine treatment.

Reduction of antigen-induced respiratory abnormalities and airway inflammation in sensitized guinea pigs by a superoxide dismutase mimetic.

Reactive oxygen species have been implicated in the pathogenesis of asthma and, in atopic asthmatics, endogenous superoxide dismutase (SOD) enzyme levels are known to decrease. This suggests that replacing a failed endogenous SOD enzyme system with a mimetic of the endogenous enzyme would be beneficial and protective. In this study we demonstrate that removal of superoxide by the SOD mimetic (SODm) M40403 reduces the respiratory and histopathological lung abnormalities due to ovalbumin (OA) aerosol in a model of allergic asthma-like reaction in sensitized guinea pigs. Both respiratory abnormalities and bronchoconstriction in response to OA challenge are nearly absent in naïve animals, while they sharply became severe in sensitized animals. In addition, OA aerosol induced a reduction of MnSOD activity which was paralleled with bronchiolar lumen reduction, pulmonary air space hyperinflation, mast cell degranulation, eosinophil infiltration, bronchial epithelial cell apoptosis, increase in myeloperoxidase activity, malonyldialdehyde production and 8-hydroxy-2'-deoxyguanosine formation in the lung tissue, as well as elevation of PGD2 in the bronchoalveolar lavage fluid. Treatment with M40403 restored the levels of MnSOD activity and significantly reduced all the above parameters. In summary, our findings support the potential therapeutic use of SOD mimetics in asthma and anaphylactic reactions and account for a critical role for superoxide in acute allergic asthma-like reaction in actively sensitized guinea pig.

Low dose DDT inhibition of hepatocarcinogenesis initiated by diethylnitrosamine in male rats: possible mechanisms.

Previously we reported a tendency for reduction of the development of glutathione-S-transferase placental form (GST-P) positive foci, recognized as preneoplastic changes in rat liver, by a low dose of 1,1-bis(p-chlorophenyl)-2,2,2-trichloroethane (DDT), which belongs to the same group of hepatic cytochrome P-450 inducers as phenobarbital and is itself a non-genotoxic hepatocarcinogen. In order to clarify the biological significance of this phenomenon, we investigated the reproducibility and changes in other parameters using an initiation-promotion model in which male F344 rats were treated with DDT at doses of 0, 0.005, 0.5, 500 ppm in the diet for 11 or 43 weeks after initiation of hepatocarcinogenesis with N-diethylnitrosamine (DEN). When 500 ppm DDT was applied, the formation of GST-P positive foci and tumor were markedly elevated. In contrast, induction of GST-P positive foci and liver tumors tended to be inhibited at a dose of 0.005 ppm, correlating with protein levels of cytochrome P450 2B1 and 3A2 (CYP2B1 and 3A2) and generation of 8-hydroxy-2'-deoxyguanosine (8-OHdG), a marker of oxidative DNA damage. mRNA levels for 8-oxoguanine glycosylase 1 (OGG1), an 8-OHdG repair enzyme, connexin 32 (Cx32), a major component of Gap junctions, and hepatic nuclear factor 1alpha (HNF-1alpha), a Cx32 regulator, were inversely correlated with GST-P positive foci and tumor formation. These results indicate that low dose DDT may indeed exhibit inhibitory effects on chemically initiated-rat hepatocarcinogenicity, in contrast to the promotion observed with high doses, and that this is related to changes in metabolizing enzymes, cell communication, and DNA damage and its repair.

Carvedilol reduces plasma 8-hydroxy-2'-deoxyguanosine in mild to moderate hypertension: a pilot study.

The purpose of this pilot study was to test whether carvedilol has a protective effect against oxidative deoxyribonucleic acid (DNA) damage in human hypertension in vivo. Carvedilol's antioxidant effect has mostly focused on lipid or amino acid so far. However, there has been no data that carvedilol reduces DNA damage in human hypertension. Never-treated mild to moderate hypertension patients and age- and sex-matched control subjects volunteered for the study. The hypertension subjects were given 12.5 or 25 mg of carvedilol or hydrochlorothiazide orally for 2 months and controls were not given any. Fasting blood samples were collected before and after carvedilol. Plasma highly sensitive 8-hydroxy-2'-deoxyguanosine (hs8-OHdG) and high-sensitivity C-reactive protein (hsCRP) were checked with the samples. There were no statistical differences in clinical characteristics in 3 groups. The hs8-OHdG declined from 9.07+/-4.23 ng/mL to 5.74+/-3.89 ng/mL (P=0.002) after carvedilol. However, it did not show significant reduction after hydrochlorothiazide (9.01+/-3.89 versus 8.23+/-4.12 ng/mL; P=NS). In the control group, the hs8-OHdG concentration was 3.41+/-2.03 ng/mL and 3.01+/-2.65 ng/mL at baseline and 2 months later, respectively (P=NS). The baseline hs8-OHdG levels were higher in hypertension groups compared with control (P=0.000). The hsCRP had no significant difference before and after the tested drugs in 2 hypertension groups (group A: 0.21+/-0.51 versus 0.19+/-0.37 mg/dL; group B: 0.20+/-0.45 versus 0.18+/-0.42 mg/dL). In conclusion, DNA damage caused by reactive oxygen species occurs more in the hypertension patients than normals. Carvedilol significantly reduces DNA damage in the hypertension patients.

Inhibition by allyl sulfides and crushed garlic of O6-methylguanine formation in liver DNA of dimethylnitrosamine-treated rats.

Garlic consumption is linked with lower incidences of certain cancers perhaps because garlic-derived allyl sulfides inhibit nitrosamine activation by cytochrome P450s. To help evaluate this view, effects of allyl sulfides on O6-methylguanine (O6MG) levels were examined in liver of rats injected with 20 mg/kg of liver carcinogen dimethylnitrosamine (DMN) and killed 3 h later. DNA was isolated and hydrolyzed, and O6MG/guanine ratios were determined by HPLC-fluorescence. Mean inhibition of O6MG formation fell from 89% for 200 to 33% for 12 mg diallyl sulfide (DAS) per kilogram gavaged 18 h before DMN injection. Gavage of DAS 3 or 6 h (instead of 18 h) before DMN injection significantly reduced inhibitions. Mean inhibitions for diallyl disulfide, diallyl sulfoxide, and diallyl sulfone (75-100 mg/kg) gavaged 18 h before DMN were 39%, 72%, and 82%. In lung and kidney, DAS produced mean inhibitions of 98% and 74% compared with 89% in liver. When methylnitrosourea was injected instead of DMN, neither DAS nor DADS inhibited O6MG formation in liver DNA. Feeding 2.5% garlic for 7 days inhibited DMN-induced O6MG formation in liver DNA by 46%, similar to that expected from the estimated yield of allyl sulfides from garlic. Hence, dosing with DAS or feeding garlic may be useful chemopreventive strategies against nitrosamine-induced cancers.

Oxidative damage of biomolecules in mouse liver induced by morphine and protected by antioxidants.

This study investigates the oxidative damage of biomolecules in livers of mice treated with morphine intraperitoneally. The oxidative damage of DNA as measured by single cell electrophoresis and high-performance liquid chromatography equipped with electrochemical and UV detection, the protein carbonyl content was measured by 2,4-dinitrophenylhydrazine method, and the malondialdehyde content was measured by the HPLC method. The activities of antioxidative enzymes, superoxide dismutase, catalase and glutathione peroxidase, and the activity of alanine aminotransferase were assayed by spectrophotometer method. Glutathione and oxidized glutathione were detected by fluorescence spectrophotometer method. All the indexes of oxidative damage, such as 8-OHdG, protein carbonyl group and malondialdehyde content, and the activity of alanine aminotransferase (n=27) increased significantly compared to those of control (n=27) (P<0.01) in livers of morphine-administered alone mice, while the indexes related with the in vivo antioxidative capacity, such as the ratio of glutathione and oxidized glutathione, activities of superoxide dismutase, catalase and glutathione peroxidase significantly decreased (P<0.01). When mice were treated with morphine combined with exogenous antioxidants, glutathione and ascorbic acid, all the indexes of oxidative damage and the activity of alanine aminotransferase showed no changes as compared to those of control (P>0.05), i.e., both glutathione and ascorbic acid completely abolished the damage of morphine on the hepatocyte. These results implied that morphine caused a seriously oxidative stress in mice livers and hence caused hepatotoxicity, while exogenous antioxidants were able to prevent the oxidative damage of biomolecules and hepatotoxicity caused by morphine. Thus, blocking oxidative damage may be a useful strategy for the development of a new therapy for opiate abuse.

Pyridoxal-aminoguanidine adduct is more effective than aminoguanidine in preventing neuropathy and cataract in diabetic rats.

We examined the ability of a pyridoxal-aminoguanidine adduct with both antiglycation and antioxidant activities in vitro to protect against neuropathy and cataract in streptozotocin-diabetic rats and compared the result with that of aminoguanidine. In vivo antiglycation and antioxidant activities were also compared between the adduct and aminoguanidine. Diabetic rats were given either of the compounds in their drinking water (9 mM) for 7 weeks. Neither compound affected body weight, blood glucose level or urine volume. The adduct, but not aminoguanidine, significantly improved motor nerve conduction velocity. The time to develop cataract was longer in adduct-treated rats than in untreated and aminoguanidine-treated rats. The increase in opacification of lenses in culture medium containing high glucose levels (55.5 mM) was more efficiently attenuated by the adduct than by aminoguanidine. Adduct and aminoguanidine similarly lowered glycated hemoglobin levels. The level of urinary 8-hydroxy-2'-deoxyguanosine, a marker of oxidative DNA damage, and the level of liver malondialdehyde plus 4-hydroxy-2-alkenals, a marker of tissue lipid peroxidation, both of which were elevated by diabetes, were significantly reduced by the adduct but not by aminoguanidine. These findings indicate that the pyridoxal-aminoguanidine adduct is superior to aminoguanidine in preventing diabetic neuropathy and cataracts, and we suggest that this may be at least partly due to the higher antioxidant activity of the former.

Translocation of glomerular p47phox and p67phox by protein kinase C-beta activation is required for oxidative stress in diabetic nephropathy.

Oxidative stress is implicated to play an important role in the development of diabetic vascular complications, including diabetic nephropathy. It is unclear whether oxidative stress is primarily enhanced in the diabetic glomeruli or whether it is merely a consequence of diabetes-induced glomerular injury. To address this issue, we examined diabetic glomeruli to determine whether oxidative stress is enhanced, as well as examined the role of protein kinase C (PKC)-beta activation in modulating NADPH oxidase activity. Urinary 8-hydroxydeoxyguanosine excretion and its intense immune-reactive staining in the glomeruli were markedly higher in diabetic than in control rats, and these alterations were ameliorated by a treatment with a selective PKC-beta inhibitor, ruboxistaurin (RBX; LY333531) mesylate, without affecting glycemia. NADPH oxidase activity, which was significantly enhanced in diabetic glomeruli and the source of reactive oxygen species (ROS) generation, was also improved by RBX treatment by preventing the membranous translocation of p47phox and p67phox from cytoplasmic fraction without affecting their protein levels. Adenoviral-mediated PKC-beta(2) overexpression enhanced ROS generation by modulating the membranous translocation of p47phox and p67phox in cultured mesangial cells. We now demonstrate that oxidative stress is primarily enhanced in the diabetic glomeruli due to a PKC-beta-dependent activation of NADPH oxidase resulting in ROS generation.

Anthocyanin-rich extract decreases indices of lipid peroxidation and DNA damage in vitamin E-depleted rats.

Anthocyanins are secondary plant metabolites responsible for the blue, purple, and red color of many plant tissues. The phenolic structure of anthocyanins conveys marked antioxidant activity in model systems via donation of electrons or hydrogen atoms from hydroxyl moieties to free radicals. Dietary intakes of anthocyanins may exceed 200 mg/day, however, little is known about their antioxidant potency in vivo. Consequently, the aim of this study was to establish whether anthocyanins could act as putative antioxidant micronutrients. Rats were maintained on vitamin E-deficient diets for 12 weeks in order to enhance susceptibility to oxidative damage and then repleted with rations containing a highly purified anthocyanin-rich extract at a concentration of 1 g/kg diet. The extract consisted of the 3-glucopyranoside forms of delphinidin, cyanidin, petunidin, peonidin, and malvidin. Consumption of the anthocyanin-repleted diet significantly improved (p <.01) plasma antioxidant capacity and decreased (p <.001) the vitamin E deficiency-enhanced hydroperoxides and 8-Oxo-deoxyguanosine concentrations in liver. These compounds are indices of lipid peroxidation and DNA damage, respectively. Dietary consumption of anthocyanin-rich foods may contribute to overall antioxidant status, particularly in areas of habitually low vitamin E intake.

Effects of benzo[a]pyrene DNA adducts on Escherichia coli DNA polymerase I (Klenow fragment) primer-template interactions: evidence for inhibition of the catalytically active ternary complex formation.

Benzo[a]pyrene diol epoxide (B[a]PDE) adducts are strong blocks of DNA replication in vitro, allowing the rare incorporation of a nucleotide across from the lesion and negligibly small extent of further bypass. To study the mechanistic details of this process, a gel-retardation assay was used to measure the dissociation constants for the binding of DNA polymerase I (Klenow fragment) (KF) to the primer-templates containing a (+)-trans- or (+)-cis-B[a]P-N(2)-dG adduct. When the primer was terminated one nucleotide before the adduct, the presence of a (+)-trans-B[a]P-N(2)-dG adduct did not affect the binding while a (+)-cis-B[a]P-N(2)-dG adduct caused a slight decrease in affinity. The presence of any dNTP decreased the affinity of KF to the modified primer-templates. (In contrast, a strong increase of the affinity to unmodified primer-templates was observed in the presence of the next correct dNTP.) Limited protease digestion experiments indicated that a closed ternary complex of KF with the modified primer-templates was not detectable in the presence of any dNTP, whereas it was clearly observed with unmodified template in the presence of the next correct nucleotide. These findings suggest that these adducts may interfere with the conformational change to the catalytically active closed ternary complex and/or cause significant destabilization of this complex. When the primers extended to the position across from the adduct, the affinity of KF was significantly decreased irrespective of the identity of the base across from the adduct, possibly explaining the low bypass of the lesion. Interestingly, the stability of these DNA-polymerase complexes correlated with nucleotide insertion kinetics for the unmodified and (+)-trans-B[a]PDE-modified templates.

Anti-8-oxo-2'-deoxyguanosine phage antibodies: isolation, characterization, and relationship to disease states.

We have used human single chain Fv (scFv) phage display antibody libraries to isolate recombinant antibodies against the DNA adduct 8-oxo-2'-deoxyguanosine (8-oxodG). One of these scFvs (175G) bound to several 8-oxodG-containing oligonucleotides whilst demonstrating no cross-reactivity with G-containing control oligonucleotides, and bound to 8-oxodG lesions introduced into DNA by treatment with methylene blue and white light. In addition, 175G inhibited the cleavage of an 8-oxodG-containing oligonucleotide by the Escherichia coli enzyme formamidopyrimidine-DNA glycosylase (Fpg). The nucleotide sequence of the 175G V(H) gene segment was 98% homologous to the published V(H) sequence of a human hybridoma derived from a patient with systemic lupus erythematosus (SLE). Sera from two SLE patients bound to damaged DNA, and this binding could be inhibited by 175G. The use of human scFv phage display libraries has thus produced a unique reagent with specificity for 8-oxodG, which may have a role in damage detection and quantitation and in modifying DNA repair activity. 175G also offers support to the hypothesis that SLE might be associated with oxidative damage to DNA.