Oncogenes, Oncogenesis, and Oxygen Radicals

The role that free radicals in general and oxygen radicals in particular play in carcinogenesis has attracted considerable attention in recent years. The oxygen radicals are undesirable but inevitable products of aerobic metabolism in the normal living cell. The cellular antioxidant defense system maintains an appropriate balance between necessary oxidative events and those that are excessive. When this critical balance cannot be maintained because of the overloading of the cellularredox system, oxygen radicals can induce cell damage. They can influence carcinogenesis by inducing DN A damage from direct oxidation or indirectly from DNA-binding products of lipid peroxidation. Oxygen radicals can induce conformational changes in the plasma membrane by lipid peroxidation and protein degradation, thus influencing membrane-associated cellular activities. They are capable of affecting membrane-bound protein kinases, growth factors and their receptors, and, therefore, signal transduction and oncogene activation. Thus, the oxygen radicals can have a major influence on oncogenes and oncogenesis. (C)1990 Academic Press.Inc.

Effect of resveratrol on pancreatic oxygen free radicals in rats with severe acute pancreatitis

AIM： To investigate the therapeutic effects of resveratrol （RESV） as a free radical scavenger on experimental severe acute pancreatitis （SAP）. METHODS： Seventy-two male Sprague-Dawley rats were divided randomly into sham operation group, SAP group, and resveratrol-treated group. Pancreatitis was induced by intraductal administration of 0.1 mL/kg 4% sodium taurocholate. RESV was given intravenously at a dose of 20 mg/kg body weight. All animals were killed at 3, 6, 12 h after induction of the model. Serum amylase, pancreatic superoxide dismutase （SOD）, malondialdehyde （MDA）, and myeloperoxidase （MPO） were determined. Pathologic changes of the pancreas were observed under optical microscope. RESULTS： The serum amylase, pancreatic MPO and the score of pathologic damage increased after the induction of pancreatitis, early （3, 6 h） SAP samples were characterized by decreased pancreatic SOD and increased pancreatic MDA. Resveratrol exhibited a protective effect against lipid peroxidation in cell membrane caused by oxygen free radicals in the early stage of SAP. This attenuation of the redox state impairment reduced cellular oxidative damage, as reflected by lower serum amylase, less severe pancreatic lesions, normal pancreatic MDA levels, as well as diminished neutrophil infiltration in pancreas. CONCLUSION： RESV may exert its therapeutic effect on SAP by lowering pancreatic oxidative free radicals and reducing pancreatic tissue infiltration of neutrophils.

Effect of Selenium Poisoning on Immune Function and Oxygen Free Radicals in Erythrocyte of Pig

[ Objective] This study was to investigate the effect of selenium（Se） on immune function and oxygen free radicals in erythrocyte of pig. [ Method] Fifteen weanling Landrace piglets as experimental animals were divided into three groups, two testing groups and one control group. For each group, Se content in whole blood, immune function of erythrocytes, activity of whole blood glutathione peroxidase（GSH-Px）, activity of blood plasma superoxide dismutase（SOD）, and blood plasma malondialdehyde（MDA） content were determined. [ Result] Compared with the control group, Se content in whole blood and blood plasma MDA content increased remarkably, while whole blood GSH-Px activity and blood plasma SOD activity decreased; RBC-C1 RR assumed a rise-fall trend, and RBC-ICR showed no obvious change. [Condusion] Se poisoning can reduce the activity of antioxidant enzymes, disturb the balance of oxygen free radicals metabolism, thereby inducing erythrooyte immune function in piglets.

THE ACTION OF CAPTOPRIL ON SCAVENGING OXYGEN FREE RADICALS

The protective effect of captopril on ischemic myocardium was studied in 40 patients with congenital heart disease accompanied with pulmonary hypertention.Twenty of these patients received captopril 50 mg b.i.d.for three months preoperatively (Group A).The other 20 patients without pretreatment with captopril were used as controls (Group B).In Group A,the cardiac output increased and the pulmonary pressure decreased significantly in the first 24 hours postoperatively,indicating a high cardiac output with a low vascular resistance.The differences or CPK,CPKMB,LDH release between Group A and Group B were highly significant or siguificant from the end of operation to 24 hours postoperatively. Myocardial protection in the reduction of the release of CPK, CPK-MB, LDH might be attributed to action on scavenging oxygen free radicals.

The influence of ultraviolet blood irradiation and oxygenation on oxygen free radicals metabolism in rabbits with soman intoxication

Objective: To investigate the effect of ultraviolet blood irradiation and oxygenation (UBIO) on the metabolism of oxygen free radicals in rabbits with acute soman intoxication. Methods: One hundred rabbits were randomly divided into 5 groups: normal control group, intoxication group, routine therapy group. UBIO therapy group and combined therapy group. After 14 d, the concentration of malondiadehyde(MDA) and activity of superoxide dismutase(SOD), glutathionperoxidase(GSH-Px), catalase (CAT) and total antioxidative capacity (T-AOC) in serum were determined respectively. Results: Compared with the normal control group, the concentration of MDA and activity of CAT in the intoxication group were significantly higher (P < 0. 05). but SOD. GSH-Px activity and T-AOC were significantly lower (P<0. 05). After UBIO or combined therapy, serum MDA level was significantly lower in comparison with intoxication group (P<0. 05). but the activity of SOD. GSH-Px, CAT and T-AOC were higher than intoxication group(P<0. 05). Conclusion: There is an obvious oxygen free radical injury in rabbits with a-cute soman intoxication. UBIO can improve the antioxidation ability of rabbits and may be applied to treat acute soman intoxication as adjunctive therapy.

Direct Measurement of Oxygen Free Radicals of the Liver Tissue Following Shock/Reperfusion and Its Significance

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Oxygen radical formation does not have an impact in the treatment of severe acute experimental pancreatitis using free cellular hemoglobin

AIM： Microcirculatory dysfunction and free oxygen radicals are important factors in the pathogenesis of severe acute pancreatitis. Additional oxygen delivery might enhance lipid peroxidation but may also improve pancreatic microcirculation. This study assesses the effect of free cellular bovine hemoglobin on the formation of oxygen radicals and microcirculation in a rodent model of severe acute pancreatitis. METHODS： Fifteen minutes after induction of acute pancreatitis Wistar rats received either 0.8 mL bovine hemoglobin （HBOC-200）, hydroxyethyl starch （HES） or 2.4 mL of normal saline to ensure normovolemic substitution. After 6 h of examination the pancreas was excised and rapidly processed for indirect measurement of lipid peroxidation products malondialdehyde （MDA） and reduced glutathione （GSH） in pancreatic tissue. RESULTS： The single application of HBOC-200 improved pancreatic microcirculation and reduced histopathological tissue damage significantly. Tissue concentration of MDA did not differ between the groups. Also no differences in GSH levels were detected.CONCLUSION： Though the single application of HBOC-200 and HES improve pancreatic microcirculation, no differences in lipid peroxidation products were detected. The beneficial effect of additional oxygen supply （HBOC-200） does not lead to enhanced lipid peroxidation.

The Maturation and Senescence in Relation to Ca^2+,CaMContent and Ca^2+-ATPase Activity and Active OxygenMetabolism in Strawberry Fruits

The changes in content of Ca2 + and CaM, Ca2 + -ATPase activity and active oxygen metabolism during strawberry (Fragaria ananassa Duch. cv. Chunxing) fruits maturation and senescence were investigated in this study. The results showed that the soluble Ca2+ content and SOD activity in fruits tended to decline and O2 production rate to increase, the Ca2 + -ATPase activity peaked at first and then declined during fruits maturation and senescence. There were the highest CaM content at white stage in preharvest fruits and at marked senescence stage in postharvest ones. The above biochemical changes in fruits stored at low temperature (4℃)were slower than those stored at normal temperature(25℃). Thus, it indicated that the stimulation of calcium messenger system and accumulation of active oxygen free radical were closely related to fruits maturation and senescence.

Granulocyte colony-stimulating factor increases extracellular glutamic acid uptake and suppresses free radicals in an experimental model of amyotrophic lateral sclerosis

Excitatory amino acid toxicity and free radical damage play important roles in amyotrophic lateral sclerosis. Granulocyte colony-stimulating factor （G-CSF） protects nerve cells exposed to high-concentrations of glutamic acid, suggesting positive effects in the treatment of amyotrophic lateral sclerosis. The present study induced in vitro motor neuron injury using glutamic acid excitotoxicity, and the biochemical effects of G-CSF on glutamic acid concentration were determined. In addition, the effects of G-CSF on superoxide dismutase, glutathione peroxidase activity in motor neurons, and malondialdehyde and nitric oxide contents were analyzed. Immunohistochemistry was performed to measure neuronal survival. Results revealed that G-CSF significantly suppressed free radical activity, inhibited excitotoxicity, and reduced apoptosis and loss of motor neurons in the anterior horn of the spinal cord.

Oxygen Radical Generation as an Index of Neurotoxic Damage

Biochemical, anatomical, and physiological characteristics of the brain make it especially vulnerable to insult. Specifically, some of these characteristics such as myelin and a high energy requirement provide for the introduction of free radical-induced insult. Recently, the biochemistry of free radicals has received considerable attention. It also has become increasingly suggestive that many drug and chemical-induced toxicities may be evoked via free radicals and oxidative stress. Major points addressed in this work are the regulation of neural-free radical generation by antioxidants and protective enzymes, xenobiotic-induced disruption of cerebral redox status, and specific examples of neurotoxic agent-induced alterations in free radicals as measured by the fluorescent probe dichlorofluorescein. This article considers that free radical mechanisms may contribute significantly to the properties of several diverse neurotoxic agents and proposes that free radicals may be common phenomena of neurotoxicity.

Inactivation of Bacillus Subtilis by Atomic Oxygen Radical Anion

UAtomic oxygen radical anion （O-） is one of the most active oxygen species, and has extremely high oxidation ability toward small-molecules of hydrocarbons. However, to our knowledge, little is known about the effects of O- on cells of micro-organisms. This work showed that O- could quickly react with the Bacillus subtilis cells and seriously damage the cell walls a s well as their other contents, leading to a fast and irreversible inactivation. SEM micrographs revealed that the cell structures were dramatically destroyed by their exposure to O-. The inactivation efficiencies of B. subtilis depend on the O- intensity, the initial population of cells and the treatment temperature, but not on the pH in the range of our investigation. For a cell concentration of 10^6 cfu/ml, the number of survived cells dropped from 10^6 cfu/ml to 10^3 cfu/ml after about five-minute irradiation by an O- flux in an intensity of 233 nA/cm^2 under a dry argon environment （30 ℃, 1 atm, exposed size： 1.8 cm^2）. The inactivation mechanism of micro-organisms induced by O- is also discussed.

The effect of reactive oxygen species of inducing apoptosis on the hepatocacinoma in the rabbits

Objective:To study the effect of reactive oxygen species of inducing apoptosis on the heptocacinoma tissues following ischemia and reperfusion and perfusion hyperoxia liquid of hepatocarcinoma. Methods: The hepatocarcinoma animal models ware established by implantation of VX2 tumor constitution mass into the left middle lobe of liver of rabbits. The animals were subjected to 60 min clamp-induced ischemia of hepatic artery distributing in the left middle lobe followed by reperfusion at 1 h, 1 d, 3 d and 7 d, respectively, and perfusion hyperoxia liquid (partial pressure of oxygen, PO2>80 kPa) at the same time with reperfusion beginning. The concentration of MDA and NO ware tested. Apoptotic changes in the hepatocarcinoma and normal hepatic tissues were observed by means of HE staining and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL). Results:The concentration of MDA in normal hepatic tissues and hepatocarcinoma tissue increased followed ischemia and reperfusion especially for reperfusion 1 h (4.61±0.40, 3.10±0.23) and restored to normal level at reperfusion 7 d in normal hepatic tissues but still kept high concentration in the hepatocarcinoma tissue. Even though concentration of MDA in normal hepatic tissues is higher than that of before ischemia and reperfusion, no difference have been found after perfusion of hyperoxia liquid, and in the hepatocarcinoma tissue, the increasing of concentration of MDA was obvious after simply ischemia and reperfusion at reperfusion 1 d (4.25±0.45). The concentration of NO in normal hepatic tissues increased for reperfusion 3 d and 7 d(18.17±0.13, 17.45±0.23),while that of hepatocarcinoma tissue decreased at reperfusion 3 d(15.95±043). After perfusion of hyperoxia liquid, the concentration of NO in normal hepatic tissues kept increasing and that decreased in the hepatocarcinoma tissues in all time point and reached the lowest level at reperfusion 1 d(14.62±0.45).The result demonstrated the changes of concentration of NO and MDA in the hepatocarcinoma tissues ware more obvious than that of normal hepatic tissues(P<0.01). Conclusion:Perfusion of hyperoxia liquid from hepatic portal vein can intensify ischemia and reperfusion injury but less so for normal hepatic tissues.

EFFECT OF ACUPUNCTURE ON BLOOD OXYGEN FREE RADICAL AND NO LEVELS IN TREATMENT OF APOPLECTIC SEQUELAE

Objective: To observe the effect of acupuncture on blood oxygen free radical (OFR) and nitric oxide (NO) levels in the treatment of apoplectic sequelae. Methods: A total of 61 cases of apoplectic patients were subjected into this study and randomly divided into "JIN San Zhen" group (n=30) and control group (n=31). Blood lipid peroxidase (LPO), superoxide dismutase (SOD), glutathione peroxidase(GSH Px) and nitric oxide (NO) contents before and after acupuncture treatment were determined with radioimmunoassay. In both groups, acupuncture was given once daily, six times a week, with 4 weeks being a therapeutic course and with the interval between two weeks being a week, 3 courses all together. In "JIN San Zhen" group, acupoints of "JIN San Zhen" were used predominately, while in control group, scalp point Motor Sensory Area (MS 8) was used as the main point. Results: Self comparison showed that after 3 courses of treatment, in both groups, LPO and NO levels decreased significantly (P<0.05-0.01), SOD and GST Px values increased considerably (P<0.05-0.01). Comparison between two groups indicated that the effects of "JIN San Zhen" group are significantly superior to those of control group in raising blood SOD and GST Px levels (P<0.05-0.01) and in lowering blood NO content (P<0.01). Analysis on the correlation between the restoration of neural function and the changes of LPO, SOD and GST Px levels suggested that the effect of acupuncture in improving neural function may be related to changes of the aforementioned indexes. Conclusion: Acupuncture therapy can significantly lower blood LPO and NO levels and evidently raise blood SOD and GST Px levels in stroke patients.

Effect of Cistanoside Compounds on Oxidative Stress and Immunity

Cistanoside compounds were studied as the scavengers of hydroxyl and superoxide anion free radicals with spin trapping ESR method in vitro. Low-temperature ESR technique, experimental technique of immunotoxicology and biochemical method were used to detect the level of reactive oxygen radicals in kidney tissue of rats and SOD level and GSH-Px activity in rat serum. The results indicated that cistanoside compounds could inhibit reactive oxygen free radicals in vitro and prevent and repair the free radical damages for diabetic nephropathy. The experimental data of 揷arbon-particle detection in mouse serum?showed that cistanoside compounds could improve the phagocytotis index of macrophages (Mj) in mice blood and increase the weights of immune organs of mice.

Induction of ischemic tolerance in rat liver via reduced nicotinamide adenine dinucleotide phosphate oxidase in Kupffer cells

AIM: To elucidate the mechanisms of hepatocyte preconditioning by H2O2 to better understand the pathophysiology of ischemic preconditioning. METHODS: The in vitro effect of H2O2 pretreatment was investigated in rat isolated hepatocytes subjected to anoxia/reoxygenation. Cell viability was assessed with propidium iodide fluorometry. In other experiments, rat livers were excised and subjected to warm ischemia/ reperfusion in an isolated perfused liver system to determine leakage of liver enzymes. Preconditioning was performed by H2O2 perfusion, or by stopping the perfusion for 10 min followed by 10 min of reperfusion. To inhibit Kupffer cell function or reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, gadolinium chloride was injected prior to liver excision, or diphenyleneiodonium, an inhibitor of NADPH oxidase, was added to the perfusate, respectively. Histological detection of oxygen radical formation in Kupffer cells was performed by perfusion with nitro blue tetrazolium. RESULTS: Anoxia/reoxygenation decreased hepatocyte viability compared to the controls. Pretreatment with H2O2 did not improve such hepatocyte injury. In liver perfusion experiments, however, H2O2 preconditioning reduced warm ischemia/reperfusion injury, which wasreversed by inhibition of Kupffer cell function or NADPH oxidase. Histological examination revealed that H2O2 preconditioning induced oxygen radical formation in Kupffer cells. NADPH oxidase inhibition also reversed hepatoprotection by ischemic preconditioning. CONCLUSION: H2O2 preconditioning protects hepato- cytes against warm ischemia/reperfusion injury via NADPH oxidase in Kupffer cells, and not directly. NADPH oxidase also mediates hepatoprotection by ischemic preconditioning.

Molecular chaperones and hypoxic-ischemic encephalopathy

Hypoxic-ischemic encephalopathy（HIE） is a disease that occurs when the brain is subjected to hypoxia,resulting in neuronal death and neurological deficits,with a poor prognosis.The mechanisms underlying hypoxic-ischemic brain injury include excitatory amino acid release,cellular proteolysis,reactive oxygen species generation,nitric oxide synthesis,and inflammation.The molecular and cellular changes in HIE include protein misfolding,aggregation,and destruction of organelles.The apoptotic pathways activated by ischemia and hypoxia include the mitochondrial pathway,the extrinsic Fas receptor pathway,and the endoplasmic reticulum stress-induced pathway.Numerous treatments for hypoxic-ischemic brain injury caused by HIE have been developed over the last half century.Hypothermia,xenon gas treatment,the use of melatonin and erythropoietin,and hypoxic-ischemic preconditioning have proven effective in HIE patients.Molecular chaperones are proteins ubiquitously present in both prokaryotes and eukaryotes.A large number of molecular chaperones are induced after brain ischemia and hypoxia,among which the heat shock proteins are the most important.Heat shock proteins not only maintain protein homeostasis; they also exert anti-apoptotic effects.Heat shock proteins maintain protein homeostasis by helping to transport proteins to their target destinations,assisting in the proper folding of newly synthesized polypeptides,regulating the degradation of misfolded proteins,inhibiting the aggregation of proteins,and by controlling the refolding of misfolded proteins.In addition,heat shock proteins exert anti-apoptotic effects by interacting with various signaling pathways to block the activation of downstream effectors in numerous apoptotic pathways,including the intrinsic pathway,the endoplasmic reticulum-stress mediated pathway and the extrinsic Fas receptor pathway.Molecular chaperones play a key role in neuroprotection in HIE.In this review,we provide an overview of the mechanisms of HIE and discuss the various treatment strategies.Given their critical role in the disease,molecular chaperones are promising therapeutic targets for HIE.

Mechanistic Investigation on the Reaction of O- with CH3CN Using Density Functional Theory

The potential energy profile of the reaction between the atomic oxygen radical anion and acetonitrile has been mapped at the G3MP2B3 level of theory. Geometries of the reactants, products, intermediate complexes, and transition states involved in this reaction have been optimized at the （U）B3LYP/6-31＋G（d,p） level, and then their accurate relative energies have been improved using the G3MP2B3 method. The potential energy profile is confirmed via intrinsic reaction coordinate calculations of transition states. Four possible production channels are examined respectively, as H＋ transfer, H-atom transfer, H2＋ transfer, and bi- molecular nucleophilic substitution （SN2） reaction pathways. Based on present calculations, the H2＋ transfer reaction is major among these four channels, which agrees with previous experimental conclusions.

Mechanisms of Inhibitory Effects of Breviscapine on Lipid Peroxidation in Rat Brain Mitochondria

The mechanisms by which breviscapine (Bre) inhibits the lipid preoxidation in rat brain mitochondria were investigated. The mitochondrial lipid peroxidation of rat brain induced by oxygen free radical was measured by thiobarbituric acid spectrophotometry. The chelating activities of Bre for Fe 2+ were tested by differential spectrum. Superoxide anion (O 2)from xanthine xanthine oxidase (Xan XO) system and hydroxyl radical (·OH) from FeSO 4 H 2O 2 system were determined with spectrophotometry. It was found that Bre could effectively inhibit the lipid peroxidation of brain mitochondria induced by free radicals driven from Xan XO and FeSO 4 H 2O 2 system. The IC 50 of Bre were 93 01 μmol·L -1 for Xan XO system and 62 18 μmol·L -1 for FeSO 4 H 2O 2 system. Bre also scavenged O 2 and ·OH produced by Xan XO and FeSO 4 H 2O 2 systems. The IC 50 of Bre were 32 63 μmol·L -1 for O - 2 and 20 22 μmol·L -1 for ·OH. Furthermore, the chelating Fe 2+ activity of Bre was shown. It may be concluded that Bre inhibited lipid peroxidation at different stages of the reaction of oxygen free redial with the mitochondria membrane: (1) the formation of ·OH; (2) the initiation of the lipid peroxidation, by chelating Fe 2+ and scavenging O 2 as well as ·OH. The scavenging oxygen free radicals and chelating iron are the mechanisms of inhibitory effect of Bre on lipid peroxidation.

Puerarin prevents high glucose-induced apoptosis of Schwann cells by inhibiting oxidative stress

Oxidative stress may be the unifying factor for the injury caused by hyperglycemia in diabetic peripheral neuropathy. Puerarin is the major isoflavonoid derived from Radix puerariae and has been shown to be effective in increasing superoxide dismutase activity. This study sought to investigate the neuroprotective effect of puerarin on high glucose-induced oxidative stress and Schwann cell apoptosis in vitro. Intracellular reactive oxygen radicals and mitochondrial transmembrane potential were detected by flow cytometry analysis. Apoptosis was confirmed by TUNEL and oxidative stress was monitored using an enzyme-linked immunosorbent assay for the DNA marker 8-hydroxy-2-deoxyguanosine. The expression levels of bax and bcl-2 were analyzed by quantitative real-time reverse transcriptase-PCR, while protein expression of cleaved caspase-3 and -9 were analyzed by means of western blotting. Results suggested that puerarin treatment inhibited high glucose-induced oxidative stress, mitochondrial depolarization and apoptosis in a dose-dependent manner. Furthermore, puerarin treatment downregulated Bax expression, upregulated bcl-2 expression and attenuated the activation of caspase-3 and -9. Overall, our results indicated that puerarin antagonized high glucose-induced oxidative stress and apoptosis in Schwann cells.

Pathogenesis of pancreatic encephalopathy in severe acute pancreatitis

BACKGROUND: Pancreatic encephalopathy (PE) is a serious complication of severe acute pancreatitis (SAP). In recent years, more and more PE cases have been reported worldwide, and the onset PE in the early stage was regarded as a poor prognosis sign of SAP, but the pathogenesis of PE in SAP still has not been clarified in the past decade. The purpose of this review is to elucidate the possible pathogenesis of PE in SAP. DATA SOURCES: The English-language literature concerning PE in this review came from the Database of MEDLINE (period of 1991-2005), and the keywords of severe acute pancreatitis and pancreatic encephalopathy were used in the searching. RESULTS: Many factors were involved in the pathogenesis of PE in SAP. Pancreatin activation, excessive release of cytokines and oxygen free radicals, microcirculation abnormalities of hemodynamic disturbance, ET-1/NO ratio, hypoxemia, bacterial infection, water and electrolyte imbalance, and vitamin B1 deficiency participated in the development of PE in SAP. CONCLUSIONS: The pathogenesis of PE in SAP has not yet been fully understood. The development of PE in SAP may be a multi-factor process. To find out the possible inducing factor is essential to the clinical management of PE in SAP.