Toxic Effects Of Free Radicals Research Articles

Effects of Borassus flabellifer L. fruit seed coat on HSC-3 cell line

Background: The seed coat of Borassus flabellifer L. fruit contains antioxidants that can neutralize the toxic effects of free radicals and can fight DNA damage due to exposure to oxidative stress. The extract of B. flabellifer is proven to have cytotoxic effects and can inhibit the growth of several types of cancer cells such as HeLa cell lines. Objective: To determine the cytotoxicity effect of extract of B. flabellifer L. fruit seed coat against HSC-3 cell line. Methods: Laboratory experimental research was conducted using HSC-3 cell lines treated with B. flabellifer L. fruit seed coat extract at concentrations of 93.75 µg/mL, 187.5 µg/mL, 375 µg/mL, 750 µg/mL, and 1,500 µg/mL, negative control DMEM-FBS 20%, and positive control anti cancer drugs Doxorubicin 3 µM. HSC-3 cell line cytotoxicity assay was performed using CCK-8 reagent. Micro plate reader at 450 nm wavelength was used to determine the viability of HSC-3 cell lines by measuring the optical density of formazan. Results: B. flabellifer fruit L. seed coat extract was able to reduce viability and was cytotoxic to HSC-3 cell lines at concentrations of 93.75 µg/mL, 187.5 µg/mL, 375 µg/mL, 750 µg/mL, and 1,500 µg/mL, with an IC50 value of 141.9 µg/mL. Conclusion: B. flabellifer L. fruit seed coat extract can reduce the ability of HSC-3 cell line cancer cells to survive by inhibiting cell proliferation due to its cytotoxicity effect.

The Applications and Mechanisms of Superoxide Dismutase in Medicine, Food, and Cosmetics.

Superoxide dismutase (SOD) is a class of enzymes that restrict the biological oxidant cluster enzyme system in the body, which can effectively respond to cellular oxidative stress, lipid metabolism, inflammation, and oxidation. Published studies have shown that SOD enzymes (SODs) could maintain a dynamic balance between the production and scavenging of biological oxidants in the body and prevent the toxic effects of free radicals, and have been shown to be effective in anti-tumor, anti-radiation, and anti-aging studies. This research summarizes the types, biological functions, and regulatory mechanisms of SODs, as well as their applications in medicine, food production, and cosmetic production. SODs have proven to be a useful tool in fighting disease, and mimetics and conjugates that report SODs have been developed successively to improve the effectiveness of SODs. There are still obstacles to solving the membrane permeability of SODs and the persistence of enzyme action, which is still a hot spot and difficulty in mining the effect of SODs and promoting their application in the future.

Brief Oxygen Exposure after Traumatic Brain Injury Hastens Recovery and Promotes Adaptive Chronic Endoplasmic Reticulum Stress Responses.

Traumatic brain injury (TBI) is a major public health concern, particularly in adolescents who have a higher mortality and incidence of visual pathway injury compared to adult patients. Likewise, we have found disparities between adult and adolescent TBI outcomes in rodents. Most interestingly, adolescents suffer a prolonged apneic period immediately post-injury, leading to higher mortality; therefore, we implemented a brief oxygen exposure paradigm to circumvent this increased mortality. Adolescent male mice experienced a closed-head weight-drop TBI and were then exposed to 100% O2 until normal breathing returned or recovered in room air. We followed mice for 7 and 30 days and assessed their optokinetic response; retinal ganglion cell loss; axonal degeneration; glial reactivity; and retinal ER stress protein levels. O2 reduced adolescent mortality by 40%, improved post-injury visual acuity, and reduced axonal degeneration and gliosis in optical projection regions. ER stress protein expression was altered in injured mice, and mice given O2 utilized different ER stress pathways in a time-dependent manner. Finally, O2 exposure may be mediating these ER stress responses through regulation of the redox-sensitive ER folding protein ERO1α, which has been linked to a reduction in the toxic effects of free radicals in other animal models of ER stress.

Salivary superoxide dismutase activity in smokeless tobacco consumers and non-consumers: A biochemical study.

Tobacco can alter the antioxidative capacity of saliva, and it is the first fluid that is exposed to tobacco. Superoxide dismutase (SOD) is the first line defense antioxidant that plays an important protective role against peroxidation of lipids, converts superoxide radicals into hydrogen peroxide, and decreases the toxic effects of free radicals. The aim of this study was to estimate and compare the levels and activity of SOD in the saliva of smokeless tobacco (SLT) consumers and non-consumers. Total of 64 individuals were divided into two groups (study and control) with 32 patients each. The patients were divided into two groups-Group I: 32 healthy individuals who do not consume SLT (control group) and Group II: 32 individuals who consume SLT for a period more than 1 year (study group). Saliva samples were collected for analysis from both the groups. The results of this study showed that antioxidant salivary SOD enzyme activity in tobacco chewers is higher in comparison to non-chewers. The present study enlightens us to the possible relationship between SOD enzyme levels, oxidative stress, and tobacco habit. In initial or early stages, antioxidant levels increase, thereby showing an evidence of endogenous activity. But as the duration of the habit increases, there is decrease in the body's defense mechanism, and the level of SOD starts to fall resulting in oral lesions. This will help in establishing the reliability of SOD in saliva as a potential biomarker of oxidative stress in tobacco chewers. Further, it may also help in establishing the role of oxidative stress in the pathogenesis of premalignant lesions and oral cancer.

The Roles of Coenzyme Q in Disease: Direct and Indirect Involvement in Cellular Functions.

Coenzyme Q (CoQ) is a key component of the respiratory chain of all eukaryotic cells. Its function is closely related to mitochondrial respiration, where it acts as an electron transporter. However, the cellular functions of coenzyme Q are multiple: it is present in all cell membranes, limiting the toxic effect of free radicals, it is a component of LDL, it is involved in the aging process, and its deficiency is linked to several diseases. Recently, it has been proposed that coenzyme Q contributes to suppressing ferroptosis, a type of iron-dependent programmed cell death characterized by lipid peroxidation. In this review, we report the latest hypotheses and theories analyzing the multiple functions of coenzyme Q. The complete knowledge of the various cellular CoQ functions is essential to provide a rational basis for its possible therapeutic use, not only in diseases characterized by primary CoQ deficiency, but also in large number of diseases in which its secondary deficiency has been found.

A Concise Review of Current In Vitro Chemical and Cell-Based Antioxidant Assay Methods.

Antioxidants remain interesting molecules of choice for suppression of the toxic effects of free radicals in foods and human systems. The current practice involves the use of mainly synthetic molecules as potent antioxidant agents. However, due to the potential negative impact on human health, there is an intensive effort within the research community to develop natural alternatives with similar antioxidant efficacy but without the negative side effects of synthetic molecules. Still, the successful development of new molecules depends on the use of reliable chemical or cell culture assays to screen antioxidant properties. Chemical antioxidant assays include the determination of scavenging ability against free radicals such as DPPH, superoxide anion radicals, hydroxyl radicals, hydrogen peroxide, and nitric oxide. Other antioxidant tests include the ability of compounds to bind and sequester prooxidant metal cations, reduce ferric iron, and attenuate the rate of lipid oxidation. Ex vivo tests utilize cell cultures to confirm entry of the molecules into cells and the ability to quench synthetic intracellular free radicals or to stimulate the increased biosynthesis of endogenous antioxidants. In order to assist researchers in their choice of antioxidant evaluation methods, this review presents background scientific information on some of the most commonly used antioxidant assays with a comparative discussion of the relevance of published literature data to food science and human nutrition applications.

Detection of superoxide dismutase (Cu–Zn) isoenzymes in leaves and pseudobulbs of Bulbophyllum morphologlorum Kraenzl orchid by comparative proteomic analysis

Typically, biological systems are protected from the toxic effect of free radicals by antioxidant defense. Extracts from orchids have been reported to show high levels of exogenous antioxidant activity including Bulbophyllum orchids but so far, there have been no reports on antioxidant enzymes. Therefore, differences in protein expression from leaves and pseudobulbs of Bulbophyllum morphologlorum Kraenzl and Dendrobium Sonia Earsakul were studied using two-dimensional gel electrophoresis and mass spectrometry (LC/MS/MS). Interestingly, the largest group of these stress response proteins were associated with antioxidant defense and temperature stress, including superoxide dismutase (Cu–Zn) and heat shock protein 70. The high expression of this antioxidant enzyme from Bulbophyllum morphologlorum Kraenzl was confirmed by activity staining on native-PAGE, and the two Cu/Zn-SODs isoenzymes were identified as Cu/Zn-SOD 1 and Cu/Zn-SOD 2 by LC/MS/MS. The results suggested that Bulbophyllum orchid can be a potential plant source for medicines and natural antioxidant supplements.

Capicor in the treatment of patients with combined cerebral and cardial pathology

In the context of the treatment of endothelial dysfunction, as a predictor of acute cerebrovascular disorder, the medicinal product Capicor (a combination of meltedonium dihydrate and gamma-butyrobetaine dihydrate) deserves attention.Such a combination provides a more powerful and faster cardio-and cerebroprotective effect of the drug under conditions of ischemia and stress of various genesis (including oxidative).Influencing the induction of biosynthesis NO, gamma-butyrobatein dihydrate protects cells from the toxic effects of free radicals, normalizes oxidative homeostasis at the cellular level, positively affects the function of the endothelium.Meltedium dihydrate preserves the aerobic pathway of metabolism under tissue hypoxia, prevents the depletion of ATP and creatinine phosphate stores in cells, the accumulation of lactic acid and the occurrence of cellular acidosis, violation of enzymatic processes and dysfunction of ion channels.These mechanisms provide pronounced and rapid NO-dependent effects: vasodilatation, anti-aggregate, anticoagulant, antioxidant. This, in turn, positively affects apoptosis and proliferation, and maintains vascular homeostasis.The drug has anti-ischemic, cerebro-, cardioprotective and immunoregulatory effects.With heart failure, Capicor improves the contractility of the myocardium, increases tolerance to physical activity, with stable angina - reduces the frequency of heart attacks. In addition, the device provides a moderate antihypertensive effect and normalizes the heart rate.In case of vascular lesions of the brain, Capicor improves cerebral hemodynamics, normalizes the metabolism in nerve cells, optimizes the consumption of oxygen by brain tissue, which results in the effect of improving cognitive functions, mental and physical activity, and the normalization of the psycho-emotional state.

Acute pancreatitis and olanzapine–valproate association: A pilot study

Introduction Drugs are responsible for 0.1–2% of acute pancreatitis incidents, which is characterized by the onset of parenchymal fat necrosis with inflammation in a previously healthy individual (Jones, 2015). Elevation of serum amylase is an effective marker of disease (de Berardinis, 1999). Valproic acid induces acute pancreatitis as a direct toxic effect of free radicals on the pancreatic tissue (Kaurich, 2008). Most cases of pancreatitis occurred within 6 months after the start of therapy with one or more antipsychotic agents (Koller, 2003). The temporal relationship of the onset of pancreatitis with the start of drug therapy further supports a cause-and-effect relationship (Alonso-Alonso, 2006). Some clinical reports noticed sporadic acute pancreatitis in patients taking both valproate and olanzapine. Methods We selected 50 psychiatric inpatients taking both olanzapine and valproate, presenting acute and aspecific gastroenteric symptomatology. We measured out their serum amylase and the time between drug prescription and start of gastroenteric simptomatology. Results and conclusions A large part of subjects associated olanzapine and valproate over 6 months before gastroenteric symptoms would start. Elevation of serum amylase rates does not suggest a link between this drug association and acute pancreatitis. Meanwhile, larger populations surveys could be helpful in early detecting sporadic cases.

Xanthine oxidase, adenosine deaminase and vitamin E levels in patients with schizophrenia

Objective: Neuronal damage caused by free radicals is believed to be effective in pathogenesis of several psychiatric disorders. This belief is due to the toxic effects of free radicals that play a role in oxidative stress. Considering that the brain is one of the most sensitive organs to the oxidative damage, the importance of oxidative stress in psychiatric disorders will become more apparent. Additionally, high oxygen use in the brain, and its structure rich in lipid, which is one of the most sensitive molecules to the free radical damage, and its having the average antioxidant system yield support oxidative stress theory in the pathogenesis of psychiatric disorders. This study aimed to determine xanthine oxidase (XO), adenosine deaminase (ADA) and vitamins E levels in patients with schizophrenia and control groups, and to investigate the relationship between schizophrenia and the parameters by comparing the measured parameters with each other. Methods: Our study sample included 30 patients diagnosed with schizophrenia. The control group consisted of 30 healthy volunteers matched by sex with similar age and smoking habits. In the patient group and the control group, adenosine deaminase, xanthine oxidase, and vitamin E were measured manually using spectrophotometric methods. Results: Serum xanthine oxidase levels in the schizophrenic group were significantly higher than the control group levels. Serum vitamin E and adenosine deaminase levels in the schizophrenia group were significantly lower than the levels of the control group. Discussion and Conclusion: The fact that mechanism of schizophrenia pathogenesis which has a wide variety of clinical symptoms and a disease process is yet to be elucidated reveals the importance of this kind of studies. In this study, low levels of antioxidant vitamin E and adenosine deaminase, and high levels of xanthine oxidase suggest that oxidative stress-mediated neuronal damage may play a role in the pathogenesis of schizophrenia. Therefore, we believe that further research with larger sample groups should be conducted.

Oxidative Stress and Down Syndrome. Do Antioxidants Play a Role in Therapy?

Oxidative stress is a phenomenon associated with imbalance between production of free radicals and reactive metabolites (e.g. superoxide and hydrogen peroxide) and the antioxidant defences. Oxidative stress in individuals with Down syndrome (DS) has been associated with trisomy of the 21st chromosome resulting in DS phenotype as well as with various morphological abnormalities, immune disorders, intellectual disability, premature aging and other biochemical abnormalities. Trisomy 21 in patients with DS results in increased activity of an important antioxidant enzyme Cu/Zn superoxide dismutase (SOD) which gene is located on the 21st chromosome along with other proteins such as transcription factor Ets-2, stress inducing factors (DSCR1) and precursor of beta-amyloid protein responsible for the formation of amyloid plaques in Alzheimer disease. Mentioned proteins are involved in the management of mitochondrial function, thereby promoting mitochondrial theory of aging also in people with DS. In defence against toxic effects of free radicals and their metabolites organism has built antioxidant defence systems. Their lack and reduced function increases oxidative stress resulting in disruption of the structure of important biomolecules, such as proteins, lipids and nucleic acids. This leads to their dysfunctions affecting pathophysiology of organs and the whole organism. This paper examines the impact of antioxidant interventions as well as positive effect of physical exercise on cognitive and learning disabilities of individuals with DS. Potential therapeutic targets on the molecular level (oxidative stress markers, gene for DYRK1A, neutrophic factor BDNF) after intervention of natural polyphenols are also discussed.

Assessment of the (anti)genotoxicity of brown propolis extracts from Brazilian Cerrado biome in a Drosophila melanogaster model

Among the great number of studies on the chemical and biological features of propolis from Brazil, none have been found on the evaluation of the biological properties of propolis from the Cerrado biome of Center-West Brazil. Propolis biological activities have principally been attributed to its phenolic compounds, notable for significant antioxidant properties responsible for reducing the toxic effects of free radicals, in addition to the anticancer potential of these compounds. The purposes of the present investigation were to determine the DPPH-radical-scavenging activities of extracts and fractions of a propolis sample from the Brazilian Cerrado biome and to evaluate their genotoxicities by performing the somatic mutation and recombination test (SMART) on wing cells of Drosophila melanogaster, using standard (ST) and high bioactivation (HB) crosses, with regular and enhanced levels of metabolizing enzymes of the cytochrome P450 type, respectively. The protective effects of propolis on the genotoxicity of doxorubicin (DXR), as well as the correlation between the radical-scavenging ability of propolis and its antigenotoxic potential were also evaluated. The ethanol extract of propolis (EEP) showed a significant level of phenolic compounds, as well as great antioxidant potential, unlike the hexane extract (HEP), of inexpressive radical-scavenging activity. Neither HEP nor EEP proved genotoxic to the offspring of ST and HB crosses, while co-treatments with DXR demonstrated the antigenotoxic properties of EEP on the ST cross, albeit proving genotoxic at the highest concentrations tested under conditions of high metabolic activation (HB cross). Solvent partitioning of EEP revealed expressive protective effects against DXR-induced genotoxicity exhibited by the n-butanol fraction, which were potentiated in HB strains, possibly due to the higher total phenolic content and more pronounced radical-scavenging properties of this fraction.

Hazards of Free Radicals in Various Aspects of Health – A Review

Hazards of Free Radicals in Various Aspects of Health – A Review The recent growth in the knowledge of free radicals and reactive oxygen species (ROS) in biology is producing a medical revolution that promises a new age of health and disease management. Free radicals are intimately involved in the cellular damage - the common pathway for cancer, aging, and a variety of diseases. Formation of free radicals has been implicated as playing a role in the etiology of cardiovascular disease, cancer, Alzheimer’s disease Parkinson’s disease, and many more. The scientific community has begun to unveil some of the mysteries surrounding this topic, and the media has begun whetting our thirst for knowledge. So that it is a basic need to know about toxic effects of free radicals affecting general health of human body.

In Vitro Effects of Isoorientin, Forsythoside B, and Verbascoside on Bovine Kidney Cortex Glutathione Reductase

Glutathione reductase (GR; E.C 1.6.4.2) catalyzes the reduction of oxidized glutathione to reduced glutathione by the nicotinamide adenine dinucleotide phosphate (NADPH) dependent mechanism. GR participates in the protection of the cell from the toxic effects of free radicals. In this study, we have investigated in vitro effects of isoorientin (C-glycosyl flavonoid), verbascoside, and forsythoside B (phenylethanoids) on purified bovine kidney cortex GR. These compounds present in many plant species that have been used as medicinal plants and have an interesting spectrum of biological activity. We have demonstrated that these compounds inhibit bovine kidney cortex GR in a concentration-dependent manner. Kinetic characterization of the inhibition is also done. Isoorientin is a noncompetitive inhibitor with respect to both glutathione disulfide (GSSG) (KiGSSG 0.023 ± 0.001 mM) and NADPH (KiNADPH 0.032 ± 0.001 mM). Forsythoside B acts as an uncompetitive inhibitor with respect to GSSG (KiGSSG 0.20 ± 0.014 mM) and NADPH (KiNADPH 0.267 ± 0.028 mM). Verbascoside acts as an uncompetitive inhibitor with respect to both GSSG (KiGSSG 0.242 ± 0.024 mM) and NADPH (KiNADPH 0.175 ± 0.016 mM). Inhibition of GR causes accumulation of reactive oxygen species and depletion of the glutathione pool. Inhibition of this enzyme may be significant in drug resistance.

Antioxidant Therapy and Neuroprotection in the Newborn

Injury to the perinatal brain is a leading cause of childhood mortality and lifelong disability. Despite recent improvements in neonatal care, no effective treatment for perinatal brain lesions is available. The newborn, especially if preterm, is highly prone to oxidative stress (OS) and to the toxic effect of free radicals (FRs). At birth, the newborn is exposed to a relatively hyperoxic environment caused by an increased oxygen bioavailability with greatly enhanced generation of FRs. Additional sources (e.g., inflammation, hypoxia, ischemia, glutamate and free iron release) occur, magnifying OS. In the preterm baby, the perinatal transition is accompanied by the immaturity of the antioxidant systems and the reduced ability to induce efficient homeostatic mechanisms designed to control overproduction of cell-damaging FRs. Improved understanding of the pathophysiological mechanism involved in perinatal brain lesions helps to identify potential targets for neuroprotective interventions, and the knowledge of these mechanisms has enabled scientists to develop new therapeutic strategies that have confirmed their neuroprotective effects in animal studies. Considering the growing role of OS in preterm newborn morbidity in respect to the higher risk of FR damage in these babies, erythropoietin, allopurinol, melatonin and hypothermia demonstrate great promise as potential neuroprotectans. This article provides an overview of the pathogenesis of FR-mediated diseases of the newborn and the antioxidant strategies now tested in order to reduce OS and its damaging effects.

New Markers of Oxidative Damage to Macromolecules

New Markers of Oxidative Damage to Macromolecules The presence of free radicals in biological material has been discovered some 50 years ago. In physiological conditions, free radicals, in the first place the ones of oxygen and nitrogen, are continuously synthesized and involved in the regulation of a series of physiological processes. The excess of free radicals is efficiently eliminated from the body in order to prevent their toxic effects. Toxic effects of free radicals may be classified into three groups: a) change of intracellular redox potential, b) oxidative modification of lipids, proteins and DNA, and c) gene activation. Lipid peroxidation involving cell membranes, lipoproteins and other molecules leads to the production of primary high-reactive intermediaries (alkyl radicals, conjugated dienes, peroxy- and alkoxyl radicals and lipid hydroperoxide), whose further breakdown generates the secondary products of lipid peroxidation: short-chain evaporable hydrocarbons, aldehydes and final products of lipid peroxidation: isoprostanes, MDA, 4-hydroxy-2, 3-transnonenal and 4,5-dihydroxydecenal which are important mediators of atherosclerosis, coronary disease, acute myocardial infarction, rheumatoid arthritis, systemic sclerosis and lupus erythematodes. Oxidative modification of proteins is manifested by changes in their primary, secondary and tertiary structures. Proteins have a specific biological function, and therefore their modification results in unique functional consequences. The nature of protein modification may provide valid information on the type of oxidants causing the damage. Chlorotyrosyl is a specific marker of oxidative damage to tyrosine caused by HOCl action, which most commonly reflects the involvement of neutrophils and monocytes in oxidative stress, while nitrotyrosyl indicates the presence of higher peroxy-nitrite synthesis. Methyonin and cysteine are the amino acids most sensitive to oxidative stress, carbonyl groups are markers of severe damage caused by free radicals, and di-tyrosyl is the most significant and sensitive marker of oxidative modification made by γ rays. >Carbonyl stress< is an important form of the secondary oxidation of proteins, where reducing sugars non-enzymatically react with amino groups of proteins and lipids and give rise to the production of covalent compounds known as advanced glycosylated end products (AGE-products). A hydroxyl radical damages the DNA, leading to a loss of base and the formation of abasic sites (AP sites), break of DNA chain and sugar modification. Final lipid peroxidation products (MDA) may covalently bind to DNA, producing the >DNA radicals< which are responsible for mutations. Measurement of an adequate oxidative stress biomarker may not only point to an early onset of disease, its progression and assessment of therapy effectiveness, but can also help in the clarification of the pathophysiological mechanisms of tissue damage caused by oxidative stress, prediction of disease prognosis and choice of appropriate treatment in the early stages of disease.

Protective effect of recombinant human somatotropin on amyloid β-peptide induced learning and memory deficits in mice

This study aimed to examine the effects of the recombinant human somatotropin (rhGH) on protecting neuronal function, and improving learning and memory deficits in mice. Mice were intracerebroventricularly (icv) injected with the aggregated amyloid β-peptide (Aβ) to mimic the Alzheimer’s disease (AD). The learning and memory functions in mice were examined by the step through test (an index of long-term memory) and the water maze performance (an index of spatial recognition memory). The results indicated that the mice treated with rhGH showed significant reduction of the error counts and the long memory retentions in the step-through test, and short swimming times in the water maze performance. Toxic effects of free radicals, damages of cholinergic neurons, and increased lipid peroxidation appeared in the cerebra of Aβ-treated mice, manifesting an increase of malondialdehyde (MDA) and decline of glutathione (GSH) level, an increment of choline acetyltransferase (ChAT) and acetylcholinesterase (AChE) activities, and a reduction of the acetylcholine (ACh) level. The gel electrophoresis pattern of the cerebra of mice treated with Aβ showed a typical DNA ladder of apoptosis. The in vivo experiments showed that the rhGH treatment significantly reversed the elevated MDA, ChAT, AChE, and the decreased GSH, ACh levels in the Aβ model mice. The results suggested that there were potential uses of the neuroprotective action of rhGH in the remedy of AD.

Molecular characterization of the Fur protein of Listeria monocytogenes

Iron is essential for the survival of almost all organisms, although excess iron can result in the generation of free radicals which are toxic to cells. To avoid the toxic effects of free radicals, the concentration of intracellular iron is generally regulated by the ferric uptake regulator Fur in bacteria. The 150 aa fur ORF from Listeria monocytogenes was cloned into pRSETa, and the His-tagged fusion protein was purified by nickel affinity column chromatography. DNA binding activity of this protein was studied by an electrophoretic mobility shift assay using the end-labelled promoters P(fhuDC) and P(fur). The results showed a decrease in migration for both promoter DNAs in the presence of the Fur protein, and the change in migration was competitively inhibited with an excess of the same unlabelled promoters. No shift in migration was observed when a similar assay was performed using non-specific end-labelled DNA. The assay showed that binding of Fur to P(fur) or P(fhuDC) was independent of iron or manganese ions, and was not inhibited in the presence of 2 mM EDTA. Inductively coupled plasma MS of the Fur protein showed no iron or manganese, but 0.48 mole zinc per mole protein was detected. A DNase I protection assay revealed that Fur specifically bound to and protected a 19 bp consensus Fur box sequence located in the promoters of fur and fhuDC. There was no requirement for iron or manganese in this assay also. However, Northern blot analysis showed an increase in fur transcription under iron-restricted compared to high-level conditions. Thus, the study suggests that under in vitro conditions, the affinity of the Fur protein for the 19 bp Fur box sequence does not require iron, but iron availability regulates fur transcription in vivo. Thus, the regulation by Fur in this intracellular pathogen may be dependent on either the structure of the DNA binding domain or other intracellular factors yet to be identified.

Implication du stress oxydant dans la physiopathologie de la schizophrénie : revue de la literature

Background Schizophrenia is a devastating psychiatric disorder with a broad range of behavioural and biologic manifestations. There are several clinical characteristics of the illness that have been consistently associated with poor premorbid adjustment, long duration of psychosis prior to treatment and prominent negative symptoms. The etiopathogenic mechanisms of lack of insight in patients with schizophrenia are to date unknown, although several hypotheses have been suggested. A point of convergence for the theoretical models occurs with regard to the neuronal membrane. Neuronal membrane contains a high proportion of polyunsaturated fatty acid and is the site for oxidative stress. Oxidative stress is a state when there is unbalance between the generation of reactive oxygen species and antioxidant defence capacity of the body. It is closely associated with a number of diseases including Parkinson's disease, Alzheimer-type dementia and Huntington's chorea. Accumulating evidence points to many interrelated mechanisms that increase production of reactive oxygen or decrease antioxidant protection in schizophrenic patients. Objectives This review aims to summarize the perturbations in antioxidant protection systems during schizophrenia, their interrelationships with the characteristic clinics and therapeutics and the implications of these observations in the pathophysiology of schizophrenia are discussed. Literature findings In schizophrenia there is evidence for deregulation of free radical metabolism, as detected by abnormal activity of critical antioxidant enzymes (superoxide dismutase, glutathione peroxidase and catalase). Many studies conclude in the decrease in the activity of key antioxidant enzymes in schizophrenia. A few studies have examined levels of non enzymatic antioxidants such as plasma antioxidant proteins (albumin, bilirubine, uric acid) and trace elements. How showed decreased levels in schizophrenic patients. Others studies have provided evidence of oxidative membrane damage by examining levels of lipid peroxidation products. Such abnormalities have been associated with certain clinical symptoms and therapeutic features. Negative symptoms have been associated with low levels of GSH-Px. Positive symptoms have been positively correlated with SOD activity. Plasma TAS was significantly lower in drug-free and haloperidol treated patients with schizophrenia. A low erythrocyte SOD activity has been found in never-treated patients, but with haloperidol treatment, SOD activity increased. Discussion These results demonstrate altered membrane dynamics and antioxidant enzyme activity in schizophrenia. Membrane dysfunction can be secondary to free a radical-mediated pathology, and may contribute to specific aspects of the schizophrenia symptomatology. Membrane defects can significantly alter a broad range of membrane functions and presumably modify behavior through multiple downstream biological effects. Phospholipid metabolism in the brain may be perturbed in schizophrenia, with reduced amounts of phosphatidylcholins and phosphatidylethanolamine in post-mortem brain tissue from schizophrenic patients, and large amounts of lipofuscin-like materiel in the oligodendrocytes. The existence of these products within cell membranes results in an unstable membrane structure, altered membrane fluidity and permeability and impaired signal transduction. Recent findings suggest that multiple neurotransmitter systems may be faulty. CNS cells are more vulnerable to the toxic effects of free radicals because they have a high rate of catecholamine oxidative metabolic activity. Neurotransmitters, like glutamate, can induce the same metabolic processes that increase free radical production and can lead to impaired dopamine-glutamate balance. These results question the role of this imbalance in the biochemical basis evoked in the etipathogenic mechanisms of schizophrenia, as well as the role of antioxidants in the therapeutic strategy and their implication in preventive and early intervention approaches in populations at risk for schizophrenia.

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 2O 2-induced stress and, upon exposure to H 2O 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 2O 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 2O 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.