Lipid peroxidation, protein thiol oxidation and DNA damage in hydrogen peroxide-induced injury to endothelial cells: role of activation of poly(ADP-ribose)polymerase

These experiments are a continuation of work investigating the mechanism of oxidant-induced damage to cultured bovine pulmonary artery endothelial cells (BPEC). Earlier experiments implicated DNA strand breakage and activation of poly(ADP-ribose)polymerase as critical steps in cell injury. In the current report, a better defined model of oxidant stress was used to investigate DNA damage, lipid peroxidation and protein thiol oxidation in BPEC following oxidant stress. The dose and time response of LDH release following exposure to H2O2 were established. H2O2 was metabolized rapidly by BPEC (t1/2 = 20 min). Hydrogen peroxide-induced increases in thiobarbituric acid (TBA) reactive material were prevented by pretreatment with the lipophilic antioxidant diphenylphenylinediamine (DPPD). However, DPPD did not decrease LDH release. Conversely, pretreatment with 5 mM 3-aminobenzamide (3AB), a competitive inhibitor of poly(ADP-ribose)polymerase, prevented LDH release from BPEC following H2O2 treatment. Dithiothreitol (DTT), a sulfhydryl reducing agent, also prevented LDH release. The effects of 3AB and DTT on H2O2-induced changes in DNA strand breaks and NAD+ and ATP levels were investigated as well as the effect of H2O2 on soluble and protein-bound thiols. As DPPD inhibited peroxidation without preventing LDH release, lipid peroxidation does not appear to play a role in the loss of BPEC viability in response to oxidant stress. As protein thiol oxidation was not caused by H2O2, it does not appear to play a causative role in cytotoxicity, although DTT may protect via maintenance of soluble thiols. H2O2 induces DNA strand breaks, which activate poly(ADP-ribose)polymerase, leading to depletion of cellular NAD+ and ATP and loss in cell viability. This supports earlier studies implicating the activation of poly(ADP-ribose)polymerase in oxidant injury to cultured endothelial cells.     

胶原蛋白肽经由Nrf2信号通路对H_2O_2诱导的肝细胞氧化损伤的保护作用(英文)

目的:氧化应激在肝脏疾病中扮演着重要的角色。胶原蛋白肽是天然的抗氧化剂,其在动物实验中已经被证实有抑制氧化应激的作用。最新研究证实胶原蛋白肽将有可能被应用在肝脏疾病的预防中,但是很少有研究报道其分子作用机制。因此本研究在胶原蛋白肽是对H2O2诱导的正常人的肝细胞系HL7702氧化损伤有保护作用的基础上,并探索其分子作用机制。方法:实验设空白对照组,H2O2模型组,胶原蛋白肽低、中、高剂量组(10,100,200μg/ml)。胶原蛋白肽各组加入相应浓度的药物预处理12 h后,与模型组一起加入300μM H2O2的H2O2共同培养12 h,空白对照组正常培养。细胞毒性是由CCK8和乳酸脱氢酶(LDH)的释放检测。抗氧化试剂盒检测细胞内活性氧的水平,超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性和丙二醛(MDA)含量的变化。Western blot检测细胞内Nrf2蛋白的表达水平。结果:胶原蛋白肽对H2O2诱导的正常人的肝细胞系HL7702氧化损伤有保护作用。胶原蛋白肽能够及时清除细胞内的活性氧,增加Nrf2的蛋白表达水平,提高超氧化物歧化酶(SOD)、过氧化氢酶(CAT)的活性,减轻脂质过氧化反应,从而保护正常人的肝细胞系HL7702。结论:总之,胶原蛋白肽通过增加Nrf2的蛋白表达水平,提高抗氧化活性,对H2O2诱导损伤的肝细胞发挥保护作用。本研究为胶原蛋白肽的分子作用机制提供了新的证据,将有助于预防氧化应激所致的肝损伤。     

Oxidant Stress and Damage in Post-Ischemic Mouse Hearts: Effects of Adenosine

Despite the general understanding that ischemia-reperfusion (I/R) promotes oxidant stress, specific contributions of oxidant stress or damage to myocardial I/R injury remain poorly defined. Moreover, whether endogenous ‘cardioprotectants’ such as adenosine act via limiting this oxidant injury is unclear. Herein we characterized effects of 20 min ischemia and 45 min reperfusion on cardiovascular function, oxidative stress and damage in isolated perfused mouse hearts (with glucose or pyruvate as substrate), and examined whether 10 μM adenosine modified these processes. In glucose-perfused hearts post-ischemic contractile function was markedly impaired (< 50% of pre-ischemia), cell damage assessed by lactate dehydrogenase (LDH) release was increased (12 ± 2 IU/g vs. 0.2 ± 0.1 IU/g in normoxic hearts), endothelial-dependent dilation in response to ADP was impaired while endothelial-independent dilation in response to nitroprusside was unaltered. Myocardial oxidative stress increased significantly, based on decreased glutathione redox status ([GSSG]/[GSG + GSSH] = 7.8 ± 0.3% vs. 1.3 ± 0.1% in normoxic hearts). Tissue cholesterol, native cholesteryl esters (CE) and the lipid-soluble antioxidant α-tocopherol (α-TOH, the most biologically active form of vitamin E) were unaffected by I/R, whereas markers of primary lipid peroxidation (CE-derived lipid hydroperoxides and hydroxides; CE-O(O)H) increased significantly (14 ± 2 vs. 2 ± 1 pmol/mg in normoxic hearts). Myocardial α -tocopherylquinone (α-TQ; an oxidation product of α -TOH) also increased (10.3 ± 1.0 vs. 1.7 ± 0.2 pmol/mg in normoxic hearts). Adenosine treatment improved functional recovery and vascular function, and limited LDH efflux. These effects were associated with an anti-oxidant effect of adenosine, as judged by inhibition of I/R-mediated changes in glutathione redox status (by 60%), α-TQ (80%) and CE-O(O)H (100%). Provision of 10 mM pyruvate as sole substrate (to by-pass glycolysis) modestly reduced I/R injury and changes in glutathione redox status and α-TQ, but not CE-O(O)H. Adenosine exerted further protection and anti-oxidant actions in these hearts. Functional recoveries and LDH efflux correlated inversely with oxidative stress and α -TQ (but not CE-O(O)H) levels. Collectively, our data reveal selective oxidative events in post-ischemic murine hearts, which are effectively limited by adenosine (independent of substrate). Correlation of post-ischemic cardiovascular outcomes with specific oxidative events (glutathione redox state, α-TQ) supports an important anti-oxidant component to adenosinergic protection.     

Salicylic acid-induced hepatotoxicity triggered by oxidative stress

Salicylic acid is a widely used nonsteroidal anti-inflammatory drug (NSAID). But it is known to cause serious liver damage occasionally. Mitochondrial dysfunction and oxidative stress are predicted to be the major factors of salicylic acid-induced liver injury. We investigated the influence of salicylic acid on ATP contents, oxygen consumption and lipid peroxidation in the presence of the same concentration of salicylic acid. Leakage of lactate dehydrogenase (LDH) was significantly higher in the presence of 5 mM salicylic acid than in its absence. Salicylic acid-induced thiobarbituric acid-reactive substance (TBARS) formation and spontaneous chemiluminescence (CL) in rat hepatocytes, whereas antioxidants, such as promethazine (PMZ) and N,N-diphenylphenylenediamine (DPPD), suppressed both TBARS formation and LDH leakage. TBARS formation in rat liver microsomes was suppressed by diethyldithiocarbamate (a specific inhibitor of cytochrome P450 (CYP)2E1) and diclofenac (a specific inhibitor of CYP2C11). These results suggest that salicylic acid-induced lipid peroxidation was related to oxidative metabolism mediated by CYP2E1 and CYP2C11.On the other hand, 5 mM salicylic acid induced a drastic decrease of ATP contents in rat isolated hepatocytes. Furthermore, mitochondrial respiration control ratio (RC ratio), calculated by State 3/State 4 also decreased with the increase of salicylic acid concentration. These findings suggest that salicylic acid would trigger mitochondrial dysfunction and cause ATP decrease, leading to lethal liver cell injury by lipid peroxidation, although this hypothesis remains to be elucidated in vivo.     

胶原蛋白肽经由Nrf2信号通路对H2O2诱导的肝细胞氧化损伤的保护作用

目的：氧化应激在肝脏疾病中扮演着重要的角色。胶原蛋白肽是天然的抗氧化剂,其在动物实验中已经被证实有抑制氧化应激的作用。最新研究证实胶原蛋白肽将有可能被应用在肝脏疾病的预防中,但是很少有研究报道其分子作用机制。因此本研究在胶原蛋白肽是对H2O2诱导的正常人的肝细胞系HL7702氧化损伤有保护作用的基础上,并探索其分子作用机制。方法：实验设空白对照组,H2O2模型组,胶原蛋白肽低、中、高剂量组（10,100,200μg/ml）。胶原蛋白肽各组加入相应浓度的药物预处理12 h后,与模型组一起加入300μM H2O2的H2O2共同培养12 h,空白对照组正常培养。细胞毒性是由CCK8和乳酸脱氢酶（LDH）的释放检测。抗氧化试剂盒检测细胞内活性氧的水平,超氧化物歧化酶（SOD）、过氧化氢酶（CAT）活性和丙二醛（MDA）含量的变化。Western blot检测细胞内Nrf2蛋白的表达水平。结果：胶原蛋白肽对H2O2诱导的正常人的肝细胞系HL7702氧化损伤有保护作用。胶原蛋白肽能够及时清除细胞内的活性氧,增加Nrf2的蛋白表达水平,提高超氧化物歧化酶（SOD）、过氧化氢酶（CAT）的活性,减轻脂质过氧化反应,从而保护正常人的肝细胞系HL7702。结论：总之,胶原蛋白肽通过增加Nrf2的蛋白表达水平,提高抗氧化活性,对H2O2诱导损伤的肝细胞发挥保护作用。本研究为胶原蛋白肽的分子作用机制提供了新的证据,将有助于预防氧化应激所致的肝损伤。     

Age-dependent effect of oxidative stress on cardiac sarcoplasmic reticulum vesicles

The oxidative stress hypothesis of aging suggests that accumulation of oxidative damage is a key factor of the alterations in physiological function during aging. We studied age-related sensitivity to oxidative modifications of proteins and lipids of cardiac sarcoplasmic reticulum (SR) isolated from 6-, 15- and 26-month-old rats. Oxidative stress was generated in vitro by exposing SR vesicles to 0.1 mmol/l FeSO4/EDTA + 1 mmol/l H2O2 at 37 degrees C for 60 min. In all groups, oxidative stress was associated with decreased membrane surface hydrophobicity, as detected by 1-anilino-8-naphthalenesulfonate as a probe. Structural changes in SR membranes were accompanied by degradation of tryptophan and significant accumulation of protein dityrosines, protein conjugates with lipid peroxidation products, conjugated dienes and thiobarbituric acid reactive substances. The sensitivity to oxidative damage was most pronounced in SR of 26-month-old rat. Our results indicate that aging and oxidative stress are associated with accumulation of oxidatively damaged proteins and lipids and these changes could contribute to cardiovascular injury.     

Role of glutathione S-transferases in oxidative stress-induced male germ cell apoptosis

Cellular apoptosis in a tissue may occur for the maintenance of proper ratio of cells or because of toxic effects of free radicals or other agents. Male germ cell apoptosis is pivotal in maintaining the proper functioning of the testis, but it is not clear how free radicals affect germ cells and what the defense mechanisms are that are used by these cells to combat the toxic effects of the products of oxidative stress. This study shows that male germ cells are susceptible to H(2)O(2)-induced stress and, upon exposure to H(2)O(2) in vitro, demonstrate a typical apoptotic phenotype that includes DNA fragmentation and formation of DNA ladders. Other changes include considerable accumulation of products of lipid peroxidation in the germ cells after exposure to H(2)O(2). Evidence is presented for the existence of multiple isoforms of glutathione S-transferases (GSTs) that possess both transferase and Se-independent peroxidase activity. Germ cell GST activity increases after H(2)O(2) exposure. If this increase in activity is inhibited with suitable inhibitors, the formation of products of lipid peroxidation is augmented, resulting in germ cell apoptosis. Also, when constitutive GST activity is inhibited, accumulation of products of lipid peroxidation occurs, resulting in increased cellular apoptosis. These data show that GSTs form a part of adaptive response of germ cells to oxidative stress and are important constituents in detoxifying the products of lipid peroxidation.     

Energy metabolism and lipid peroxidation of human erythrocytes as a function of increased oxidative stress.

To study the influence of oxidative stress on energy metabolism and lipid peroxidation in erythrocytes, cells were incubated with increasing concentrations (0.5-10 mM) of hydrogen peroxide for 1 h at 37 degrees C and the main substances of energy metabolism (ATP, AMP, GTP and IMP) and one index of lipid peroxidation (malondialdehyde) were determined by HPLC on cell extracts. Using the same incubation conditions, the activity of AMP-deaminase was also determined. Under nonhaemolysing conditions (at up to 4 mM H2O2), oxidative stress produced, starting from 1 mM H2O2, progressive ATP depletion and a net decrease in the intracellular sum of adenine nucleotides (ATP + ADP + AMP), which were not paralleled by AMP formation. Concomitantly, the IMP level increased by up to 20-fold with respect to the value determined in control erythrocytes, when cells were challenged with the highest nonhaemolysing H2O2 concentration (4 mM). Efflux of inosine, hypoxanthine, xanthine and uric acid towards the extracellular medium was observed. The metabolic imbalance of erythrocytes following oxidative stress was due to a dramatic and unexpected activation of AMP-deaminase (a twofold increase of activity with respect to controls) that was already evident at the lowest dose of H2O2 used; this enzymatic activity increased with increasing H2O2 in the medium, and reached its maximum at 4 mM H2O2-treated erythrocytes (10-fold higher activity than controls). Generation of malondialdehyde was strictly related to the dose of H2O2, being detectable at the lowest H2O2 concentration and increasing without appreciable haemolysis up to 4 mM H2O2. Besides demonstrating a close relationship between lipid peroxidation and haemolysis, these data suggest that glycolytic enzymes are moderately affected by oxygen radical action and strongly indicate, in the change of AMP-deaminase activity, a highly sensitive enzymatic site responsible for a profound modification of erythrocyte energy metabolism during oxidative stress.     

Apolipoprotein E protects against oxidative stress in mixed neuronal-glial cell cultures by reducing glutamate toxicity

Apolipoprotein E (ApoE) deficiency has been shown to adversely affect outcome after transient cerebral ischemia and head trauma. Since oxidative stress contributes to these injuries, the ability of ApoE to reduce irreversible oxidative damage was studied in primary mixed neuronal-glial cell cultures. Cells (13-16 days in vitro) were exposed to 50 microM hydrogen peroxide (H2O2) for 30 min, and toxicity was determined by the release of lactate dehydrogenase (LDH) 24 h after exposure. The presence of recombinant human ApoE2 (100, 300, or 1000 nM) in the culture media partially protected against oxidative injury. This protection was not reversed by pre-treatment with receptor associated protein. The NMDA receptor antagonist, MK-801, also provided partial protection against H2O2 toxicity. The degree of protection was similar to that conferred by ApoE treatment. The protective effects of ApoE and MK-801 were not additive; no ApoE protection was observed in cultures treated with MK-801 prior to H2O2 exposure. ApoE treatment had no effect on H2O2 stimulated glutamate release, but did increase the rate of glutamate uptake via the high affinity glutamate transporter in H2O2 treated cultures. Pre-treatment with ApoE also conferred partial protection against glutamate-induced LDH release. Taken together, these findings suggest that ApoE protects mixed neuronal-glial cell cultures against irreversible oxidative injury from H2O2 by reducing secondary glutamate excitotoxicity.     

Protective effect of Homer 1a against hydrogen peroxide-induced oxidative stress in PC12 cells

Oxidative stress-induced cell damage is involved in many neurological diseases. Homer protein, as an important scaffold protein at postsynaptic density, regulates synaptic structure and function. Here, we reported that hydrogen peroxide (H(2)O(2)) induced the expression of Homer 1a. Down-regulation of Homer 1a with a specific small interfering RNA (siRNA) exacerbated H(2)O(2)-induced cell injury. Up-regulation of Homer 1a by lentivirus transfection did not affect the anti-oxidant activity, but significantly reduced the reactive oxygen species (ROS) production and lipid peroxidation after H(2)O(2)-induced oxidative stress. Overexpression of Homer 1a attenuated the loss of mitochondrial membrane potential (MMP) and ATP production induced by H(2)O(2), and subsequently inhibited mitochondrial dysfunction-induced cytochrome c release, increase of Bax/Bcl-2 ratio and caspase-9/caspase-3 activity. Furthermore, in the presence of BAPTA-AM, an intracellular free-calcium (Ca(2+)) chelator, overexpression of Homer 1a had no significant effects on H(2)O(2)-induced oxidative stress. These results suggest that Homer 1a has protective effects against H(2)O(2)-induced oxidative stress by reducing ROS accumulation and activation of mitochondrial apoptotic pathway, and these protective effects are dependent on the regulation of intracellular Ca(2+) homeostasis.     

Leptins and leptin receptor expression in the goldfish (Carassius auratus). Regulation by food intake and fasting/overfeeding conditions

Intermedin (IMD)(1-53) is a novel member of the calcitonin gene-related peptide superfamily and has potent cardioprotective effects against myocardial injury induced by ischemia-reperfusion (I/R). To explore the mechanism of the IMD(1-53) cardioprotective effect, we studied the anti-oxidant effects of IMD(1-53) on myocardial injury induced by I/R in vivo in rat and H(2)O(2) treatment in vitro in rat cardiomyocytes. Compared with sham treatment, I/R treatment induced severe lipid peroxidation injury in rat myocardium: plasma malondialdehyde (MDA) content and myocardial LDH activity was increased by 34% and 85% (all P<0.01); Mn-superoxide dismutase (Mn-SOD) and catalase (CAT) activity was reduced 80% and 86% (all P<0.01), respectively, and the protein levels of the NADPH oxidase complex subunits gp91(phox) and p47(phox) were markedly increased, by 86% (P<0.05) and 95% (P<0.01), respectively; IMD(1-53) treatment ameliorated lipid peroxidation injury: plasma MDA content and myocardial LDH activity was decreased by 30% (P<0.05) and 36% (P<0.01); Mn-SOD and CAT activity was elevated 1.0- and 4.3-fold (all P<0.01), respectively; and the protein levels of gp91(phox) and p47(phox) were reduced, by 28% and 36% (both P<0.05), respectively. Concurrently, IMD(1-53) treatment markedly promoted cell viability and inhibited apoptosis in cardiomyocytes as compared with H(2)O(2) treatment alone. Furthermore, IMD(1-53) increased the ratio of p-ERK to ERK by 66% (P<0.05) as compared with I/R alone, and the protective effect of IMD(1-53) on H(2)O(2)-induced apoptosis was abolished by preincubation with PD98059, a MEK inhibitor. IMD(1-53) may improve the oxidative stress injury induced by I/R via inhibiting the production of reactive oxygen species and enhancing ERK phosphorylation.     

Synergistic interactions of Ferulic acid with Ascorbic acid: Its cardioprotective role during isoproterenol induced myocardial infarction in rats

Studies on the lipid peroxidation and antioxidant changes and their significance during myocardial injury have provided a new insight into the pathogenesis of heart disease. The heart failure subsequent to myocardial infarction may be associated with an antioxidant deficit as well as increased myocardial oxidative stress. The present study was designed to evaluate the effect of the combination of ferulic acid and ascorbic acid on antioxidant defense system and lipid peroxidation against isoproterenol (ISO)-induced myocardial infarction in rats. Induction of rats with isoproterenol (150 mg/kg body weight daily, i.p.) for 2 days resulted in a marked elevation in lipid peroxidation, serum marker enzymes (LDH, CPK, GOT, and GPT), and a significant decrease in activities of endogenous antioxidants (SOD, GPx, GST, CAT, and GSH). Pre-co-treatment with the combination of ferulic acid (20 mg/kg body weight/day) and ascorbic acid (80 mg/kg body weight/day) orally for 6 days, significantly attenuated these changes when compared to the individual treatment groups. Histopathological observations were also in correlation with the biochemical parameters. Thus, ferulic acid and ascorbic acid significantly counteracted the pronounced oxidative stress effect of ISO by the inhibition of lipid peroxidation, restoration of antioxidant status, and myocardial marker enzymes levels. In conclusion, these findings indicate the synergistic protective effect of ferulic acid and ascorbic acid on lipid peroxidation and antioxidant defense system during ISO-induced myocardial infarction and associated oxidative stress in rats.     

Dietary magnesium intake influences circulating pro-inflammatory neuropeptide levels and loss of myocardial tolerance to postischemic stress

Severe dietary Mg restriction (Mg(9), 9% of recommended daily allowance [RDA], plasma Mg = 0.25 mM) induces a pro-inflammatory neurogenic response in rats (substance P [SP]), and the associated increases in oxidative stress in vivo and cardiac susceptibility to ischemia/reperfusion (I/R) injury were previously shown to be attenuated by SP receptor blockade and antioxidant treatment. The present study assessed if less severe dietary Mg restriction modulates the extent of both the neurogenic/oxidative responses in vivo and I/R injury in vitro. Male Sprague-Dawley rats maintained on Mg(40) (40% RDA, plasma Mg = 0.6 mM) or Mg(100) (100% RDA, plasma Mg = 0.8 mM) diets were assessed for plasma SP levels (CHEM-ELISA) during the first 3 weeks and were compared with the Mg(9) group; red blood cell (RBC) glutathione and plasma malondialdehyde levels were compared at 3 weeks in Mg(9), Mg(20) (plasma Mg = 0.4 mM), Mg(40), and Mg(100) rats; and 40-min global ischemia/30-min reperfusion hearts from 7-week-old Mg(20), Mg(40), and Mg(100) rats were compared with respect to functional recovery (cardiac work, and diastolic, systolic, and developed pressures), tissue LDH release, and free radical production (ESR spectroscopy and alpha-phenyl-N-tert butylnitrone [PBN; 3 mM] spin trapping). The Mg(40) diet induced smaller elevations in plasma SP (50% lower) compared with Mg(9), but with a nearly identical time course. RBC glutathione and plasma malondialdehyde levels revealed a direct relationship between the severity of oxidative stress and hypomagnesemia. The dominant lipid free radical species detected in all I/R groups was the alkoxyl radical (PBN/alkoxyl: alpha(H) = 1.93 G, alpha(N) = 13.63 G); however, Mg(40) and Mg(20) hearts exhibited 2.7- and 3.9-fold higher alkoxyl levels, 40% and 65% greater LDH release, and lower functional recovery (Mg(20) < Mg(40)) compared with Mg(100). Our data suggest that varying dietary Mg intake directly influences the magnitude of the neurogenic/oxidative responses in vivo and the resultant myocardial tolerance to I/R stress.     

Effects of Selenium on Calcium Signaling and Apoptosis in Rat Dorsal Root Ganglion Neurons Induced by Oxidative Stress

Ca(2+) is well known for its role as crucial second messenger in modulating many cellular physiological functions, Ca(2+) overload is detrimental to cellular function and may present as an important cause of cellular oxidative stress generation and apoptosis. The aim of this study is to investigate the effects of selenium on lipid peroxidation, reduced glutathione (GSH), glutathione peroxidase (GSH-Px), cytosolic Ca(2+) release, cell viability (MTT) and apoptosis values in dorsal root ganglion (DRG) sensory neurons of rats. DRG cells were divided into four groups namely control, H(2)O(2) (as a model substance used as a paradigm for oxidative stress), selenium, selenium + H(2)O(2). Moderate doses and times of H(2)O(2) and selenium were determined by MTT test. Cells were preterated 200 nM selenium for 30 h before incubatation with 1 μM H(2)O(2) for 2 h. Lipid peroxidation levels were lower in the control, selenium, selenium + H(2)O(2) groups than in the H(2)O(2) group. GSH-Px activities were higher in the selenium groups than in the H(2)O(2) group. GSH levels were higher in the control, selenium, selenium + H(2)O(2) groups than in the H(2)O(2) group. Cytosolic Ca(2+) release was higher in the H(2)O(2) group than in the control, selenium, selenium + H(2)O(2) groups. Cytosolic Ca(2+) release was lower in the selenium + H(2)O(2) group than in the H(2)O(2). In conclusion, the present study demonstrates that selenium induced protective effects on oxidative stress, [Ca(2+)](c) release and apoptosis in DRG cells. Since selenium deficiency is a common feature of oxidative stress-induced neurological diseases of sensory neurons, our findings are relevant to the etiology of pathology in oxidative stress-induced neurological diseases of the DRG neurons.     

Deficiency in Beclin1 attenuates alcohol-induced cardiac dysfunction via inhibition of ferroptosis

BackgroundBinge drinking leads to compromised mitochondrial integrity and contractile function in the heart although little effective remedy is readily available. Given the possible derangement of autophagy in ethanol-induced cardiac anomalies, this study was designed to examine involvement of Beclin1 in acute ethanol-induced cardiac contractile dysfunction, in any, and the impact of Beclin1 haploinsufficiency on ethanol cardiotoxicity with a focus on autophagy-related ferroptosis.MethodsWT and Beclin1 haploinsufficiency (BECN^+/?) mice were challenged with ethanol for one week (2 g/kg, i.p. on day 1, 3 and 7) prior to assessment of cardiac injury markers (LDH, CK-MB), cardiac geometry, contractile and mitochondrial integrity, oxidative stress, lipid peroxidation, apoptosis and ferroptosis.ResultsEthanol exposure compromised cardiac geometry and contractile function accompanied with upregulated Beclin1 and autophagy, mitochondrial injury, oxidative stress, lipid peroxidation and apoptosis, and ferroptosis (GPx4, SLC7A11, NCOA4). Although Beclin1 deficiency did not affect cardiac function in the absence of ethanol challenge, it alleviated ethanol-induced changes in cardiac injury biomarkers, cardiomyocyte area, interstitial fibrosis, echocardiographic and cardiomyocyte mechanical properties along with mitochondrial integrity, oxidative stress, lipid peroxidation, apoptosis and ferroptosis. Ethanol challenge evoked pronounced ferroptosis (downregulated GPx4, SLC7A11 and elevated NCOA4, lipid peroxidation), the effect was alleviated by Beclin1 haploinsufficiency. Inhibition of ferroptosis using LIP-1 rescued ethanol-induced cardiac mechanical anomalies. In vitro study noted that ferroptosis induction using erastin abrogated Beclin1 haploinsufficiency-induced response against ethanol.ConclusionsIn sum, our data suggest that Beclin1 haploinsufficiency benefits acute ethanol challenge-induced myocardial remodeling and contractile dysfunction through ferroptosis-mediated manner.     

氧化胁迫对水稻幼苗抗冷力的影响

利用Ｈ２Ｏ２和甲基紫精（ＭＶ）对水稻幼苗作三种不同程度的氧化胁迫预处理。结果表明：轻度氧化胁迫预处理（１０ｕｍｏｌ／ＬＨ２Ｏ２或１０ｕｍｏｌ／ＬＭＶ处理４ｈ）提高了水稻幼苗的抗冷力,严重氧化胁迫预处理（１０ｕｍｏｌ／ＬＨ２Ｏ２或１０ｕｍｏｌ／ＬＭＶ分别处理１６ｈ和４０ｈ）则削弱水稻幼苗的抗冷力。氧化胁迫预处理刺激了水稻幼苗叶片抗氧化酶（ＳＯＤ,ＣＡＴ,ＰＯＸ和ＡＰＸ）的活性。经冷胁迫后,不同预处理苗的叶片抗氧化酶活性、膜脂过氧化和膜结构的变化趋势不同：轻度氧化胁迫预处理使幼苗仍保持较高的抗氧化酶活性,减轻了由冷胁迫引起的膜脂过氧化和细胞膜的渗漏程度,而严重氧化胁迫预处理则相反。因此,水稻幼苗对氧化胁迫感知并作出反应的机制（氧化应激机制）在水稻幼苗对低温反应和适应过程中起着很重要的调节作用。     

神经元缺氧复氧损伤时氧自由基的毒性作用及其机制

在原代分离培养Ｗｉｓｔａｒ乳鼠大脑皮质神经元上研究了缺氧复氧损伤（Ｈ／Ｒ）对神经细胞乳酸脱氢酶（ＬＤＨ）,漏出率,死亡率和脂质过氧化物含量的影响,并选用一氧化氮（ＮＯ）合酶抑制剂Ｌ－ＮＧ－硝基－精氨酸（Ｌ－ＮＮＡ）巯基供体Ｎ－乙酰半胱氨酸（ＮＡＣ）和超氧化物歧化酶（Ｃｕ,Ｚｎ－ＳＯＤ）三种自由基清除剂进行预保护等方法来探讨机制。结果表明 Ｈ／Ｒ损伤引起ＬＤＨ漏出率,细胞死亡率和脂过氧化物含量极显著     

Magnesium deficiency in vitro enhances free radical-induced intracellular oxidation and cytotoxicity in endothelial cells.

The effect of magnesium (Mg)-deficient culture on endothelial cell susceptibility to oxidative stress was examined. Bovine endothelial cells were cultured in either control sufficient (0.8 mM) or deficient (0.4 mM) levels of MgCl2. Oxygen radicals were produced extracellularly by the addition of dihydroxyfumarate and Fe(3+)-ADP. Isolated Mg-deficient endothelial cells produced 2- to 3-fold higher levels of thiobarbituric acid (TBA)-reactive materials when incubated with this free radical system. Additional studies were performed using digitized video microscopy and 2',7'-dichlorofluorescein diacetate (DCFDA) as an intracellular indicator for oxidative events at the single cell level. In response to the exogenous oxidative stress, endothelial cells exhibited a time-dependent increase in fluorescence, suggestive of intracellular lipid peroxidation. The increase in cellular fluorescence began within 1 min of free radical addition; the Mg-deficient cells exhibited a more rapid increase in fluorescence than that of Mg-sufficient cells. In separate experiments, cellular viability was assessed using the Trypan blue exclusion assay. Mg deficiency increased cytotoxicity of the added oxyradicals, but the loss of cellular viability began to occur only after 15 min of free radical exposure, lagging behind the detection of intracellular oxidation products. These results suggest that increased oxidative endothelial cell injury may contribute to vascular injury during Mg deficiency.     

Salinity up-regulates the antioxidative system in root mitochondria and peroxisomes of the wild salt-tolerant tomato species Lycopersicon pennellii

The effect of salinity on the antioxidative system of root mitochondria and peroxisomes of a cultivated tomato Lycopersicon esculentum (Lem) and its wild salt-tolerant related species L. pennellii (Lpa) was studied. Salt stress induced oxidative stress in Lem mitochondria, as indicated by the increased levels of lipid peroxidation and H(2)O(2). These changes were associated with decreased activities of superoxide dismutase (SOD) and guaiacol peroxidases (POD) and contents of ascorbate (ASC) and glutathione (GSH). By contrast, in mitochondria of salt-treated Lpa plants both H(2)O(2) and lipid peroxidation levels decreased while the levels of ASC and GSH and activities of SOD, several isoforms of ascorbate peroxidase (APX), and POD increased. Similarly to mitochondria, peroxisomes isolated from roots of salt-treated Lpa plants exhibited also decreased levels of lipid peroxidation and H(2)O(2) and increased SOD, ascorbate peroxidase (APX), and catalase (CAT) activities. In spite of the fact that salt stress decreased activities of antioxidant enzymes in Lem peroxisome, oxidative stress was not evident in these organelles.     

氧化胁迫对Alkalibacterium sp. F26防御酶和辅因子的影响

将一株能够高产过氧化氢酶的低度嗜盐嗜碱茵Alkalibacterium sp.F26作为模式微生物,采用高效液相色谱技术测定胞内代谢物浓度,研究氧化胁迫对其防御酶活性和辅因子的影响.研究结果表明:相比低浓度H2O2(＜1 mmol/L)胁迫,此菌株在高浓度H2O2(＞1 mmol/L)胁迫下的应答表现曼为明显:经3 mmol/L H2O2胁迫后胞内CAT酶活为106.54 U/mg protein,是对照产量的1.76倍;ATP浓度则从对照浓度20.55 μmol/L下降到17.80 μmol/L;NAD 浓度自对照样品的69.89 μmol/L减少至31.77 μmol/L.由于ATP和NAD 浓度的减少,相比未经过H2O2胁迫菌体.细胞能荷值EC从0.77降低至0.68,NADH/NAD 则从0.08增加至0.41.然而,这种应答机制在细胞受到低浓度H2O2的胁迫后并不明显:除发现100 μmol/L H2O2能够导致细胞防御机制的激活而使胞内ATP浓度相比对照有所增加的情况外,经50 μmol/L和500 μmol/L H2O2胁迫后胞内ATP水平从对照的22.69 μmol/L只下降到22.38 μmol/L和13.70 μmol/L;并且此种胁迫条件下NADH浓度变化也不显著.