Free Radicals

Free Radicals

The electrons that revolve around the nucleus of an atom occupy regions known as orbitals, each of which can be occupied by two electrons. An atom is most stable when each orbital is occupied by two electrons. An atom containing a single electron in its outermost orbital is known as a free radical, as are molecules containing such atoms. Most free radicals react rapidly with other atoms, thereby filling the unpaired orbital thus free radicals normally exist for only brief periods of time before combining with other atoms. Free radicals are diagramed with a dot next to the atomic symbol. Examples of biologically important free radicals are superoxide anion, O2 hydroxyl radical, OH and nitric oxide, NO . Note that a free radical configuration can occur in either an ionized or an un-ionized atom. A number of free radicals play important roles in the normal and abnormal functioning of the body.

Antioxidant Defenses

Thioredoxin, a thiol-disulfide oxidoreductase, is possibly involved in antioxidant protection in human coronary arteries (424). 2. Exercise-induced plasma oxidative stress could be responsible for the prevention of atherosclerosis by stimulating arterial antioxidant response. In addition, vitamin E could be deleterious in exercisers by inhibiting antioxidant enzyme buildup in the arterial wall in LDL receptor - - male mice fed an atherogenic diet (425). 3. In humans, a greater activity of antioxidant enzyme in intracranial arteries may contribute to their greater resistance to atherosclerosis. With increasing age intracranial arteries respond with accelerated atherogenesis when their antioxidant protection decreases, relatively more than that of extracranial arteries (426).

Oxygen Free Radicals

Free Radicals Iron Copper

Although oxygen must ultimately completely oxidize all biological matter, its propensity for biological oxidation is considerably slowed by the fact that in its ground state (lowest energy state), it exists as a triplet spin state (Figure 1.2), whereas most biological molecules are in the singlet state as their lowest energy level. Spin inversion is relatively slow, so that oxygen reacts much more easily with other triplet-state molecules or with free radicals than it does with singlet-state molecules. The arrangement of electrons in most atoms and molecules is such that they occur in pairs, each of which have opposite intrinsic spin angular momentum. Molecules having one or more unpaired electrons are termed free radicals they are generally very reactive, and will act as chain carriers in chemical reactions. Thus, the hydrogen atom, with one unpaired electron, is a free radical, as are most transition metals and the oxygen molecule itself. The dioxygen molecule has two unpaired...


It has been proposed that one of the causes for the retarded development of preimplantation embryos in culture compared to those developed in vivo is oxidative stress. Potential sources of such stress include the use of high oxygen tension (i.e., 20 ), exposure to light, and the presence of transitional metals in the culture medium (162). Therefore, several studies have examined the effect of known antioxidants on preimplantation embryo development, although the data to date remain rather contradictory. Supplementation of medium with superoxide dismutase (SOD), which dis-mutases superoxide radicals, increased the development of mouse zygotes beyond the 2-cell block to the blastocyst stage (163,164). However, several studies have reported that SOD had no effect on either mouse (165), rabbit (166) or bovine (167) embryo development in vitro. The conflicting reports as to the benefits of adding antioxidants to culture media may in part be explained by their use in isolation and not as...

Edited by Ira Wolinsky

Klimis-Zacas Nutrients and Gene Expression Clinical Aspects, Carolyn D. Berdanier Antioxidants and Disease Prevention, Harinda S. Garewal Advanced Nutrition Micronutrients, Carolyn D. Berdanier Nutrition and Women's Cancers, Barbara Pence and Dale M. Dunn Nutrients and Foods in AIDS, Ronald R. Watson Nutrition Chemistry and Biology, Second Edition, Julian E. Spallholz,

Mechanical Disruption of Microbial Cells

The liquid shear cell disruption is often associated with the cavitation phenomenon that involves formation of vapor cavities in liquid due to local reduction in pressure that could be affected by ultrasonic vibrations, local increase in velocity, and so forth. Collapse and rebound of the cavities will occur until an increase in pressure causes their destruction. On the collapse of the cavitation bubble, a large amount of energy is released as mechanical energy in the form of elastic waves that disintegrate into eddies. According to Doulah (1977), the eddies larger than the dimension of the cell will move it from place to place whereas the smaller eddies will impart motions of different intensities to the cell, creating a pressure difference across the cell. When the kinetic energy content of the cell exceeds the cell wall strength, the cell disintegrates. Cavitation also produces free radicals that lead to protein denaturation (Save et al. 1997).

Classification of Materials According to their Magnetic Properties

For substances with w 0, the induced magnetic moment caused by the external field, points in the same direction as the external field. Materials with positive but very small (for most materials w 10 6) susceptibility are called paramagnets (some gases, organic free radicals, most metals).

The Specific Gene Complements of L pneumophila Paris Lens and Philadelphia

O-type cytochrome ubiquinol oxidase and a type V secretion system (autotransporter). Strain Lens contains four specific transcriptional regulators and three specific proteins with eukaryotic domains (Table 1.2A), two of which are ankyrin repeat proteins. Except four specific transcriptional regulators, Strain Philadelphia 1 codes two specific ankyrin repeat and one F-box domain protein. Strain Philadelphia 1 codes, in addition to the three peptide methionine sulfoxide reductase regulators msrA that are conserved in all strains, three additional orthologs msrA1,2,3 on its specific 65-kb pathogenicity island. msrA2 and msrA3 are homologous to msrA and msrB encoding antioxidant repair enzymes, characterized as virulence determinants in E. coli, Neisseria gonorrhea and Mycoplasma genitalium (Dhandayuthapani et al. 2001 Moskovitz et al. 1995 Skaar et al. 2002). In the same island the Philadelphia 1 specific magA gene, coding a protein putatively implicated in the maturation of the...

Dxidt Vjk kjX vxy 0 vy9k3y vy

Oxidation of lipids with participation of free radicals. There exists an intermediate state in which lipids themselves become radicals, and this process is auto-catalytic. Characteristic concentrations of radicals are 1CT6 mole liter and the half-renovation time is 1 sec.

Physiological mechanisms increasing risk of cardiovascular disease from smoking

There is a growing body of evidence suggesting that oxidation of low density lipoprotein (LDL)-cholesterol particles may be a pivotal step in atherogenesis (28-30). Cigaret smoking, even for brief periods, can markedly enhance LDL-cholesterol oxidation as well as decrease high-density lipoprotein cholesterol (31). It also depletes body stores of vitamin C that may be an important antioxidant protection. Intake of the anti-oxidant beta carotene has been shown to be inversely related to the risk of coronary events among current smokers (relative risk 0.30) and former smokers (relative risk 0.60), but was not beneficial in persons who had never smoked (32,33).

Conventional Msbased Proteomics Technologies

Several candidate tumor markers were identified to be upregulated (1.4- to 10.6-fold) in lung adenocarcinomas when compared with normal lung tissue. Among these, the antioxidant enzyme AOE372, cytosolic inorganic pyrophosphatase (PPase), mu-class glutathione transferase 4 (GSTM4), and ubiquitin carboxy-terminal hydrolase L1 (UCHL1) were increased 10.6-, 7.6-, 4.0-, and 3.5-fold, respectively. The frequency of elevated expression of these proteins in lung adenocarcinomas was found to range from 35.5 to 96.8 among the 93 tumors examined. GSTM4 was the most consistently over-expressed protein, being upregulated in 96.8 of the tumors. Correlations were observed between overexpression of some proteins and specific clin-icopathological variables, including tumor differentiation (AOE372), tumor subhistology (PPase), and a positive smoking history (PPase and UCHL1). In addition, the increased abundance of both AOE372 and UCHL1 correlated with the upregulation of these genes at the mRNA level.

Iron Metabolism and Oxidative Stress Response

From these observations, it is understandable why the Fur protein is not only autoregulated and regulated by cAMP-CAP (De Lorenzo et al., 1988), but also by OxyR and SoxRS (Zheng et al, 1999). After treatment of cells with H2O2, OxyR induces a set of genes with clear antioxidant activities. OxyR induction of Fur synthesis should diminish the formation of HO radicals generated by the reaction of H2O2 with intracellular iron. SoxRS induces oxidative stress-response genes after treatment of cells with O2-generating compounds. The induction of Fur by SoxRS should decrease the generation of HO radicals (Zheng et al., 1999).

CLS Formation Requires Activation of Apoptotic Pathways Mediated by Mitochondrial Cytochrome c Release and Caspase3

Pathways of capillary-like structure (CLS) formation. (A) Fas-FasL croslinkage does not modify CLS formation. (A1) Cells treated with anti-Fas blocking antibody (A2) Control, non-treated cells. (B) Flow cytometry analysis of melanoma cells stained with PI. (B1) Control cells were detached from plastic 10 h after seeding (B2) cells were detached from Matrigel 10 h after seeding (B3) cells were incubated with 10 M RT for 24 h, detached from plastic, seeded on Matrigel, then detached from Matrigel and analyzed. (C) CLS formation requires activation of apoptotic pathways mediated by mitochondrial cytochrome c release and caspase-3 activation. (Ca) Time-dependent cytochrome c release into cytosol. Lane 1, cells grown on plastic for 10 h, lanes 2-5, cells grown on Matrigel for 2, 4, 6, and 8 h. (Cb) Active caspase-3 in cytosol. Lane 1, cells grown on plastic lanes 2-5, cells grown on Matrigel for 2, 4, 8, and 10 h . (Cc) Effect of antioxidants on active caspase-3. Lane 1, active...

Determine Whether Exposure Prevalence Varies as Expected Among the Controls

An empirical application of this strategy comes from a study of serum lycopene (an antioxidant form of carotenoid found in fruits and vegetables) in relation to the risk of prostate cancer (Vogt et al., 2002). A multicenter case-control study was conducted in the late 1980s in Atlanta, Detroit, and 10 counties in New Jersey. Controls were chosen through random-digit dialing for men under age 65 and through the Health Care Financing Administration records for men age 65 and older. Among a much larger pool of participants, 209 cases and 228 controls had blood specimens analyzed for lycopenes. Serum lycopene was inversely associated with risk of prostate cancer and found to be lower among African-American controls as compared to white controls (Table 5.4). To corroborate the plausibility of lower levels among African Americans (who experience a markedly higher risk of prostate cancer generally), the authors examined pertinent data from the National Health and Nutrition Examination...

Health Supplement Alert Melatonin

Melatonin is a hormone produced by the pineal gland in the brain. The use of melatonin obtained from animal pineal tissue is not recommended because of the risk of contamination. The synthetic form of melatonin does not carry this risk. However, melatonin is an over-the-counter dietary supplement and has not been evaluated for safety, effectiveness, and purity by the FDA. All of the potential risks and benefits may not be known. Supplements should be purchased from a reliable source to minimize the risk of contamination. Melatonin has been used in treating insomnia, overcoming jet lag, improving the effectiveness of the immune system, and as an antioxidant. The most significant use is for the short-term treatment of insomnia at low doses. Individuals wishing to use melatonin should consult with their primary health care provider or a pharmacist before using the supplement. Possible adverse reactions include headache and depression. Drowsiness may occur within 30 minutes after taking...

Regulation of the Pulmonary Vascular Signaling System by ROS and RNS

Cells are normally protected from the cytotoxic effects of02' by SOD, but when elevated, 02 can either be dismutated to produce H202, or it can interact with NO to produce 0N00 An overproduction of free radicals exert cytotoxic effects, but these oxidants species can also interact with cell-control mechanisms and potentially contribute to signaling processes. As shown in the Figure 1, certain signaling systems are very sensitive to low levels of 02' and H202 normally produced by cells, and these mechanisms are likely to participate in physiological regulation. In addition, other signaling systems activated by conditions generating higher levels of oxidants are generally associated with the mechanisms contributing to pathophysiological processes and cellular responses to oxidative stress. Observations demonstrating the potential importance of oxidant regulation of ion transport mechanisms are slowly accumulating. It has been shown that elevated levels ofH202 cause K+ channel-dependent...

Regulation of Pulmonary Vascular Remodeling by ROS and RNS During Pulmonary Hypertension

Other examples of up-regulated gene expression by redox or ROS signaling are adhesion proteins, antioxidant enzymes, NOS, receptors, and many respiratory adaptations to hypoxic environments. ROS and RNS can also influence the growth and death ofcells through a variety ofmechanisms. Cellular release of ROS is now know to serve as an intercellular messenger to stimulate proliferation via mechanisms common to natural growth factors. For example, growth factors appear to activate Akt protein kinase B pathways through oxidant mechanisms and initiate cell division. 02' seems to mediate the downstream effects of Ras and Rac in non-phagocytic cells, and it contributes to the unchecked proliferation ofRas-transformed cells (15).

Dietary lipids and cancer

As reviewed above, the evidence is strong for a link between adiposity and breast cancer and for endometrial cancer, both in post-menopausal women. The most consistent theory implicates the production of oestrogens by the excess adipose tissue. Adipose tissue is an important site for the conversion of androgens (particularly androstene-dione, secreted from the adrenal cortex) to oestrogens, oestradiol and oestrone. The development of some forms of breast and endometrial cancer is stimulated by oestrogens, and hence the association with dietary fat or obesity. The intake of some antioxidants, including tocopherols and lycopene (the red carotenoid pigment of tomatoes), has been linked to protection against certain cancers, including prostate. Even if these findings should be confirmed, it should be emphasized that cancer prevention may not be as simple as supplementation with the antioxidant vitamins at high doses. A number of supplementation studies has been carried out, none so far...

Pentose Phosphate Pathway of Glucose Oxidation

In other tissues, the essential product of the pentose phosphate pathway is not the pentoses but the electron donor NADPH, needed for reductive biosynthesis or to counter the damaging effects of oxygen radicals. Tissues that carry out extensive fatty acid synthesis (liver, adipose, lactating mammary gland) or very active synthesis of cholesterol and steroid hormones (liver, adrenal gland, gonads) require the NADPH provided by the pathway. Erythrocytes and the cells of the lens and cornea are directly exposed to oxygen and thus to the damaging free radicals generated by oxygen.

Modulation Of The Respiratory Burst

Ceruloplasmin, lactoferrin, and transferrin are proteins that bind 2 moles of metal ion per mole of protein, thus reducing the ions available for facilitation of chemical reactions. Ceruloplasmin binds copper while lactoferrin and transferrin bind iron without the release of free radicals (Urban et al., 1995).

Is cADPR Accumulation by Hypoxia Mediated by the Production of Reactive Oxygen Species by the Mitochondrial Electron

In addition to their studies on the whole lung, however, Waypa et al. (85) presented data from cultured pulmonary artery smooth muscle cells. These data are consistent with the idea that an increase in ROS production, measured by dichlorofluorescein fluorescence, at complex III in the ETC triggers an increase in cytoplasmic Ca2+ concentration. It is notable, however, that the increase in the Fura-2 fluorescence ratio reported is small and non-uniform in individual cells, and does not appear to be associated with cell contraction. Furthermore, one glance at the literature informs us that investigations from a variety of laboratories have provided contrary data (32). For example, in pulmonary arteries a decrease in ROS has been measured by lucigenin chemiluminescence (5, 6, 8), consistent with the classical view that a fell in Po2 results in a consequent fall in ROS (15). Not surprisingly, therefore, it has been stated that the direct measurements of ROS are so demanding that they...

Immune Privilege 11 The Problem

A functional central nervous system (CNS) is essential for mammalian survival therefore, the CNS must be defended from insults and other pathogens. The molecules (e.g., free radicals, cytokines, proteases) produced in vast quantities by the activated immune system to combat pathogens have the demonstrated potential to disrupt CNS function (1-3). To balance these opposing needs, (sufficient defense of the CNS without loss of CNS function), the CNS and immune system have developed a unique relationship referred to as immune privilege. Disruptions in this unique relationship leading to disregulated CNS inflammation are now thought to contribute to the onset and progression of many diverse types of CNS pathology, including CNS autoimmune diseases such as multiple sclerosis (MS), Rasmussen's encephalitis, and narcolepsy neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and stroke and the secondary neurodegeneration associated with spinal cord injury (3-10)....

The Big the Old and the Immortal

Random damage theories emphasize the wear and tear on the body that accumulates with metabolic action. It is the source of damage that differs from one theory to another. One holds that the buildup of metabolically produced antioxidants is the key factor, a spinoff of the long-standing conjecture that the faster an animal's metabolism is, the shorter its life span. A second theory focuses on proteins that change over time until their effect on the body alters for the worse, especially when the proteins are involved in cellular repair. There is, for example, the altered connective tissue that causes the cross-connections stiffening tendons and ligaments. Another such change is the glyco-sylation of proteins or nucleic acids, in which a carbohydrate is added. Glycosylation is involved

How Does The Cholesterol Get Into The Wall Of The Artery

The bad LDL cholesterol circulates in the blood and sticks to the wall of the arteries. Cholesterol is more likely to be forced into the wall of the artery in people with high blood pressure. The LDL cholesterol is taken up by the cells of the artery wall after it has been changed or oxidized by the addition of oxygen. This is why it was thought that foods and drugs containing antioxidants might reduce the amount of cholesterol in the artery. Unfortunately, none of these antioxidants, for example, vitamin E, has been shown to be helpful. Indeed, vitamin E may be harmful.

ROS May Contribute to Insulin Resistance

Adipocytes exposed to H2O2 in vitro manifest impaired lipid synthesis, glycogen synthetase activity, and glucose uptake in response to insulin (105). Type II diabetics show an inverse relationship between measures of oxidant stress and insulin action (106,107). Antioxidant therapy with vitamin E was associated with improved glucose metabolism in some studies of diabetics (108). Collectively, the studies implicate oxidant stress in the metabolic components of insulin resistance observed in subjects with the risk factor cluster. If ROS participate in cardiovascular risk and disease, then benefits of antioxidants should be evident among high-risk subjects, e.g., those in the heart outcomes prevention evaluation (HOPE) study (109). In this study, vitamin E had no significant benefit, whereas the ACE inhibitor ramipril reduced risk. However, vitamin E in a wide range of concentrations of the racemic mixture as well as specific enantiomers had no effect on ROS produced by VSMCs stimulated...

Importance of Cytoprotection

Such a plethora of radicals produced as a result of normal cellular metabolism needs to be rapidly scavenged by cytoprotective enzymes and antioxidants present in the cell and cellular membranes, both hydrophobic and hydrophilic compartments. The Figure 10.1 'Ward' cascade showing the cooperation between cytoprotective enzymes and antioxidants for scavenging of reactive oxygen and reactive nitrogen species.

The main defence mechanisms against cellular stress

Korsloot et al. (2004) reviewed the cellular stress-defence responses with an emphasis on arthropods. In the book, the authors distinguished five different systems (i) basal signal transduction systems, (ii) stress proteins, (iii) the oxidative stress response, (iv) metallothionein and associated systems, and (v) mixed-function oxygenase. It was also noted that there are many crosslinks between the different stress-defence systems. These crosslinks help to coordinate the cellular response, which is needed to maintain integrity. In addition, many genes of the stress-defence system have promoters responding to more than one challenge. For example, the metallothionein promoter has metal-responsive elements enabling induction by metal stress, but it also has antioxidant-responsive elements and steroid hormone receptor-binding sites. Korsloot et al. (2004) even went one step further and argued that the different systems cooperate as a single, integrated, cellular stress-defence system. In...

Importance of Cell Type in Response to Oxidative Stress

Over the past years it has become apparent that the cell type is an important determinant of the extent of oxidative stress that may occur. Both the latent activities of cytoprotective enzymes in specific cell types, as well as the ability of the cell to respond rapidly to an oxidative insult by the upregulation of such enzymes, will be important predeterminants of the fate of the cell. Table 10.1 shows the concentrations of both antioxidants and cytoprotective enzymes in a variety of tissues. While the liver is well provided with antioxidant protection, the brain has very low levels, so the ability to respond rapidly to an oxidative insult by upregulation of gene transcription and translation will be an important determinant of survival or death. Cells such as hepatocytes have high levels of expression and Table 10.1 Antioxidant and cytoprotective enzyme content in a variety of rat tissues Antioxidants Cytoprotective enzymes Table 10.1 Antioxidant and cytoprotective enzyme content in...

Results And Discussion

There are a variety of antioxidants in herbs and plants that, when ingested, could provide important protection from strong oxidants, e.g., peroxynitrite and hypochlorite hydrogen peroxide. It is important to supplement our major antioxidants, such as vitamins C and E, uric acid, and glutathione in the reduced state. These substances protect us against attack by oxidants, which can damage our important macromolecules including DNA, RNA, proteins, and lipids. Therefore, new nontoxic dietary antioxidants were explored that could supplement the usual fare of antioxdants. Dose response was determined for the following extracts PBE, HBE, and green tea at full strength and at 1 10, 1 100, and 1 1000 dilutions. The final concentration in the tube was actually one fifth of these concentrations. Using the NG and the superoxide together produced peroxynitrite, which reacts with luminol to produce light. The light is used as an easily determined end point to measure antioxidant effect or...

Modelling Treatment Scenarios General Comments

Itively, some combinations of therapies have been shown, for various reasons, to be less effective than each of the therapies separately. Fairly recently, it was found that ionizing radiation can inhibit chemotherapy-induced cell death (apoptosis) in certain glioblas-toma cells (Yount et al. 1998). (There have also been suggestions that antioxidants may in fact be exploited by the cancer cells to help prevent their destruction.) This type of multimodality treatment failure can be attributed to the induced mutation of cells exposed to harsh chemicals or radiation. Cancer cells are, by definition, mutated 'normal' cells, so with the accumulation of mutations, the cancerous cells progressively become more malignant and treatment-resistant. We discuss polyclonal models later when we discuss a modification of the basic model to consider chemotherapy treatment.

Prevention Of H Pylorirelated Gastric Cancer

Alternative targets for gastric cancer prevention involve environmental cofactors. As mentioned previously, dietary supplementation with antioxidants, or diets rich in fresh fruit have been associated with a decreased gastric cancer risk and are beneficial for many reasons (198,199). Cigarette smoking has also been linked to gastric tumors, among many other conditions (171).

Summary And Conclusions

In isolated, perfused rodent hearts, acetaminophen has modest, but statistically significant, concentration-dependent cardiac and coronary vascular properties. It displays cardioprotection, both ultrastruc-turally and functionally, in the reperfused, stunned myocardium. One mechanism of protection appears to involve antioxidant actions against both hydroxyl radical and peroxynitrite. More work is needed to confirm these results, and to extend them to include regional myocardial ischemia reperfusion, chronic vs. acute administration of acetaminophen, and experiments in whole animals. Collectively, results from such investigations should guide us to the future design of experiments in cardiac patients.

Glutamate Channels And Disease

Numerous studies have indicated that overstimulation of Ca2+-permeable glutamate receptors has neurotoxic effects. John Olney has coined the term 'excitotoxicity' to describe this process. Excessive activation of NMDA, AMPA, or kainate receptors is associated with a large increase in intracellular calcium, which triggers a cascade of events that can lead to neuronal death. The rise in intracellular calcium comes from Ca2+ influx, both through glutamate receptors themselves and through voltage-gated Ca2+ channels activated by the depolarisation which results from GluR activation. The reason why elevation of Ca2+ causes cell death is less clear, but has been postulated to include the activation of Ca2+-dependent proteases, disturbance of cellular metabolism, accumulation of toxic free radicals, and macromolecular degradation. Overactivation of glutamate receptors is also associated with enhanced neuronal excitation and may lead to recurrent excitation of neuronal circuits and thus to...

Implications for control

Chemical and physical hazards may also become significant in addition to microbiological hazards. Chemical contaminants can be naturally present in foods or can be introduced during processing when compounds generally recognized as safe (GRAS) (e.g. antioxidants, sulfiting agents, preservatives) are not used according to government regulatory guidelines. It is incumbent upon the processor to ensure that chemical compounds such as sanitizers and lubricants are used with strict adherence to existing regulations and product specifications. Physical contaminants can be defined as any materials not normally found in food that can produce an injury or illness in the consumer. They can enter the food supply through contaminated raw materials, faulty processing equipment, improper packaging and poor employee hygiene practices. Examples of physical hazards that can compromise food safety include metal fragments, gravel, plastic, glass particles and jewelry. These hazards affect the product's...

The mixedfunction oxygenase system

Proteins) before phase II metabolism can detoxify them. This process is called bioactivation. A well-known example is the activation of certain polycyclic aromatic hydrocarbons (a group of chemicals occurring in crude oil, diesel exhaust, and tar) to very reactive intermediates that are highly mutagenic and carcinogenic. The production of such very reactive compounds with obvious negative metabolic effects can be seen as an unavoidable evolutionary trade-off against the capacity to metabolize toxins and xenobiotics. In addition, with some substrates cytochrome P450 produces large amounts of ROS as a by-product. These two negative side effects of biotransformation may explain why upregulated monooxygenase is often accompanied by upregulation of antioxidant enzymes and heat-shock proteins. Fig. 6.8 provides an overview of the different possibilities for the fate of a foreign compound that undergoes biotransformation.

Restrict Inference to Disease Outcome That Can Be Ascertained Accurately

In a case-control study of prostate cancer, analyses were divided based on case aggressiveness to evaluate the potential implications of both selection bias (incomplete ascertainment of cases) as well as true biologic differences in etiology for more versus less aggressive tumors (Vogt et al., 2002). This multicenter case-control study was conducted in the late 1980s in Atlanta, Detroit, and 10 counties in New Jersey. Controls were chosen through random-digit dialing for men under age 65 and through the Health Care Financing Administration records for men age 65 and older. Among a much larger pool of participants, 209 cases and 228 controls had blood specimens analyzed for lycopenes and other specific types of carotenoids, antioxidants found in fruits and vegetables. For lycopenes (Table 9.5), the inverse association with prostate cancer risk was much more pronounced among aggressive cases as compared to nonaggressive cases (as defined in the footnote to the table), with odds ratios...

Long Term Effects ofET1 on Blood Vessels in Experimental Hypertension

Increased collagen, fibronectin, and intercellular adhesion molecule (ICAM-1) content in the vessel wall of aldosterone-infused rats. ETA receptor antagonism decreased oxidative stress, normalized the hypertrophic remodeling, decreased collagen and fibronectin deposition, and reduced ICAM-1 abundance in the vascular wall of aldosterone-infused rats, whereas hydralazine lowered blood pressure and reduced NADPH activity in aorta but did not affect the other vascular changes. ET blockade thus exerts beneficial effects on vascular remodeling, fibrosis, oxidative stress, and adhesion molecule expression in aldos-terone-induced hypertension (31). In salt-loaded stroke-prone SHR (SHR-SP) rats, whose hypertension has an ET-1 component, administration of antioxidants such as the superoxide dismutase mimetic Tempol decreased the media to lumen ratio of mesenteric arteries (32). However, whereas in mice NADPH oxidase appears to be of major importance in mediation of ROS generation induced by...

Methods of detection and quantification of foodborne pathogens

In general, the above-mentioned problems can be solved by using anti-oxidant buffer mixes consisting of phenolic compounds absorbers (e.g. polyvinylpolypirrolidone PVPP), antioxidants (e.g. ascorbic acid, glutha-tion), mild detergents (e.g.Tween 20), and buffers (e.g. buffered phosphate) (Rossen et al., 1992). Also, to increase the efficiency of microbial removal, large volumes of extracting buffers are needed in relation to the amount of material processed (50-250ml). However, the methods of analysis only permit processing small amounts of extracted material (less than 1 ml). Thus, an additional stage of removal of large particulate debris, and separation or concentration of microbial cells, is required. The removal of large materials which are generated by more vigorous extraction methods is simply accomplished by cheese-cloth filtration. Separation and concentration of microbial cells from the suspension can be performed by membrane filtration, centrifugation or immunomagnetic...

Effect on Subarachnoid Hemorrhage

Activated neutrophils may play a major role in the pathogenesis of cerebral arterial vasospasm or cerebral injury. Such processes cause neutrophils to degranulate, aggregate, adhere to the endothelium, infiltrate, and release highly reactive compounds that promote inflammatory local responses. Oxygen radicals released from neutrophils are considered to be toxic to en-dothelial cells and to cause endothelial damage. Additionally, it is considered that free radicals from neutrophils induce cellular injury with inactivation of nitric oxide, a known vasodilator (Kajita et al 1994). We reported that inacti-vation of nitric oxide by superoxide anions contributes to the development of vasospasm (Suzuki et al. 1992). A later report (Arai et al. 1993) demonstrated that HA1077 can prevent the production of superoxide anions in neutrophils as well as the migration of neutrophils.

Cobalt Chemistry and Biochemistry

Cobalt, like iron and nickel, has access to a variety of oxidation and spin states and has more than five 3d electrons in its lower oxidation state (i.e. it is electron rich). Cobalt (and nickel) are special, in that they are not only generally electron rich, especially in lower oxidation states and in low-spin states, but that some of their 3d electrons are forced into exposed s- (or p-) orbitals in these low-spin states by the preferred symmetry of their complexes. This means that the tetragonal low-spin d7 Co(II) ion is a reactive free radical, and this property is exploited in vitamin B12, a coenzyme required for many enzymatic transformations requiring a source of free radicals, such as the Class II ribonucleotide reductases of Lactobacillus sp. (Chapter 2). Some eight years after its isolation in 1948, the structure of the 'anti pernicious anaemia factor', vitamin B12, was determined. Vitamin B12 is an alkyl-cobalt(III) complex of a substituted corrin (Figure 12.5), certainly...

Cytokines In Noninfectious Central Nervous System Disease

Movement, and postural instability or impaired balance and coordination. PD is distinguished neu-ropathologically by the selective loss of dopaminergic neurons of the substantia nigra and in related brainstem nuclei. Loss of the neurotransmitter dopamine results in uncontrolled firing of spared neurons, resulting in movement disorders in patients. The causes of PD as well as the mechanisms that result in neurodegeneration are largely unknown. Inheritance contributes to the development of familial forms of the disease, which represent only about 10 of all cases of PD. Most forms of PD are sporadic in nature and are not inherited. Oxidative stress and mitochondrial dysfunction have been suggested to have roles in PD (445). Metabolism of dopamine results in increased production of free radicals that may be toxic to dopaminergic neurons. Increased lipid peroxidation and iron levels and decreased glutathione transferase observed in the substantia nigra of patients with PD supports a...

Concluding Remarks

Fig. 1 a Some proposed roles of NK cells as modulators of adaptive immune responses. Immunoregulation such as this could occur anywhere in the body, e.g., blood, secondary lymphoid organs, and target tissues. Key to this complex pattern may be the regulation of cytokine responses in NK cells. The right part of the picture reflects disease-promoting roles. For example, IFN-y maydirectlystimulate Th1 development in T cells (upper right) and this cytokine may also prime DC to become better stimulators (lower right). DC may also be killed by NK cells (lower left), which would downregulate T cell responses. TGF-p secreted by NK cells has been reported to downregulate Ab production via CD8+ T cells (middle left), and NK cells showing a Th2-like cytokine pattern may counteract IFN-y and downregulate Th1 responses (upper left). b In tissues, NK cells could potentially contribute to tissue destruction by direct cytotoxicity, perhaps triggered via activating KIR or by NKG2D. In addition, IFN-y...

Dna Damage By Radiation And Oxidation

It has been demonstrated repeatedly that ionizing radiation damages the DNA in cells, often leading to both chromosomal aberrations and mutations. The direct effects of ionizing radiation include breaks to single or both DNA strands, base modifications, and damage to the carbohydrate components associated with the DNA. The most important indirect effect of radiation is the production of free radicals from cellular water, which react with the DNA (reviewed in Reference 388). Tumors may develop when the cellular DNA repair mechanisms fail to detect and correct these changes or are themselves compromised. Mass spectrometric methodologies have been developed for the study of oxidative DNA damage produced by free radicals, particularly by the highly reactive hydroxyl radical ( OH), as well as for the investigation of enzymatic repair of the DNA (reviewed in Reference 390). Enzymatic hydrolysis, with deoxyribonuclease and or exonucleases, produced nucleosides from DNA. This was followed by...

Influences on Thrombogenecity

Vascular thrombogenicity is induced by progressive LDL oxidation, and alterations of the antioxidant oxidant balance of LDL particle in favor of the antioxidant tone are protective against the thrombotic response triggered by oxidative stress (399). oxLDL may promote expression of CD40 and CD40L in human atheromas. Platelet-enriched plasma of mice deficient in CD40L showed markedly delayed fibrin clot formation (400). oxLDL induces surface tissue factor pathway and dysregulates fibrinolysis with a net increase in the inhibitory rate (reviewed in ref. 401).

Plant Chemical Defenses

Aspergillus Flavus

Photooxidants, such as the quinones (Fig. 3.3) and furanocoumarins, increase epidermal sensitivity to solar radiation. Assimilation of these compounds can result in severe sunburn, necrosis of the skin, and other epidermal damage on exposure to sunlight. Feeding on furanocoumarin-producing plants in daylight can cause 100 mortality to insects, whereas feeding in the dark causes only 60 mortality. Insect herbivores can circumvent this defense by becoming leaf rollers or nocturnal feeders (Harborne 1994) or by sequestering antioxidants (Blum 1992).

Flavonoids And Stilbenes

Both structures nicely illustrate the different characteristic oxygenation patterns in aromatic rings derived from the acetate or shikimate pathways. With the stilbenes, it is noted that the terminal ester function is no longer present, and therefore hydrolysis and decarboxylation have also taken place during this transformation. No intermediates, e.g. carboxylated stilbenes, have been detected, and the transformation from cinnamoyl-CoA malonyl-CoA to stilbene is catalysed by the single enzyme. Resveratrol has assumed greater relevance in recent years as a constituent of grapes and wine, as well as other food products, with antioxidant, anti-inflammatory, anti-platelet, and cancer preventative properties. Coupled with the cardiovascular benefits of moderate amounts of alcohol, and the beneficial antioxidant effects of flavonoids (see page 151), red wine has now emerged as an unlikely but most acceptable medicinal agent. flavonoids are particularly beneficial, acting as antioxidants...

Gsh H202 Gssg 2h20 2gsh Rooh Gssg H20

It shares this function with but the substrate specificity and affinity and cellular location of these two antioxidant enzymes are different. CAT is a tetramer with a molecular weight of 240 kDa. CAT is mainly localized to peroxisomes, but mitochondria and other intracellular organelles such as endoplasmic reticulum may also contain some CAT activity. It is detectable in alveolar type II pneumocytes and macrophages (14). Heme (Fe3+) is a required to be bound to the enzyme's active site for its catalytic functions. The primary function of CAT is to remove H202 produced in the peroxisomes due to enzymes such as flavoprotein dehydrogenase in the (3-oxidation of fatty acids, urate oxidase, and the metabolism of D-amino acids.

Evaluation and Preparation of the Infertile Couple for In Vitro Fertilization

Cases of unexplained failure of fertilization have been found to be due to unrecognized subtle abnormalities of sperm structure. When strict morphology shows 4 or fewer normal sperm, the chance of failed fertilization is high. Insemination with a larger sperm number raises the fertilization rate to almost normal but the percentages of implantation and ongoing pregnancy delivery are reduced by 40-50 (19), whereas intracytoplasmic sperm injection (ICSI) has been as successful as with other infertility factors (20). These findings suggest an embryotoxic effect of a high concentration of these very abnormal sperm which can be avoided by achieving fertilization with ICSI. In some cases, sperm morphology improves with observation or treatment with antioxidants. Sperm morphology may be impaired in smokers and may be improved by giving vitamin C, 1.0 g daily. Fragmented DNA can be an unrecognized cause of infertility. This can now be determined clinically by flow cytometry sperm chromatin...

Clinical Correlates

Lateral Cervical Cyst

Neural crest cells (Fig. 15.2) are essential for formation of much of the cran-iofacial region. Consequently, disruption of crest cell development results in severe craniofacial malformations. Since crest cells also contribute to the conotruncal endocardial cushions, which septate the outflow tract of the heart into pulmonary and aortic channels, many infants with craniofacial defects also have cardiac abnormalities, including persistent truncus arteriosus, tetralogy of Fallot, and transposition of the great vessels. Unfortunately, crest cells appear to be a particularly vulnerable cell population and are easily killed by compounds such as alcohol and retinoic acid. One reason for this vulnerability may be that they are deficient in superoxide dismutase (SOD) and catalase enzymes that are responsible for scavenging free radicals that damage cells. Examples of craniofacial defects involving crest cells include the following

Neutral Mg2dependent Sphingomyelinases nSMase

Sphingomyelin signaling in response to external agents (TNF-a, oxidized LDL) results in a SMase at the plasma membrane level. It is thus disappointing that none of the cloned nSMases are localized there. In contrast, two recent reports characterize plasma membrane-associated nSMases. Veldman et al. 65 described a nSMase in caveolae of human skin fibroblasts. This enzyme was inhibited by a peptide that corresponded to the scaffolding domain of caveolin, suggesting a direct molecular interaction of both proteins. Such interaction would in turn imply a cytosolic orientation of the caveolar nSMase. Stimulation of overexpressing fibro-blasts with TNF-a resulted in caveolin-sensitive nSMase activity in the non-caveo-lar fractions. These results suggest that caveolar nSMase may be involved in TNF-a-signaling. More recently, mechanical (haemodynamic) stress has been shown to stimulate the activity of nSMase, but not of aSMase, in caveolae, leading to the generation of ceramide 41 . Working on...

Saccharomyces Cerevisiae

Life Cycle Saccharomyces Cerevisiae

Or white rot fungus, which is found commonly on dead trees and wood fragments on the forest floor. To date, white rot fungus is the only basidomycete (mushroom-forming fungus) that has had its genome sequenced (Martinez et al. 2004). White rot owes its name to the fact that the fungus 'bleaches' wood by degrading the (brown-coloured) lignin, rendering the white cellulose visible. Lignin forms protective sheaths around cellulose fibrils in plant cell walls. The biodegradation of lignin by white rot is supported by unique extracellular oxidative enzymes (peroxidases and oxidases) that act non-specifically via the generation of free radicals attacking the lignin molecule. There are many other ecologically important fungi commonly found on dead organic material that contribute to processing of organic matter and cycling of nutrients in natural ecosystems (Aspergillus, Trichoderma, Cladosporium, Morteriella), but their genomes have yet to be sequenced.

The oxidative stressresponse system

Under the term oxidative stress come a variety of phenomena that are an unavoidable consequence of aerobic metabolism. By definition all aerobic organisms need oxygen, but at the same time they must avoid the inherently cytotoxic effects of oxygen. Toxicity of oxygen is not due to O2 itself but to reactive oxygen derivatives, generated by cellular processes. These derivatives are jointly referred to as reactive oxygen species (ROS). Several of these ROS are free radicals that is, molecules or elements with one or more unpaired electrons in the outer orbital. The best-known ROS are the free radicals superoxide radical (O*-), hydroxyl radical (OH*), and nitric oxide radical (NO* the lack of a paired electron is indicated by * in the chemical formula). Non-radical ROS are hydrogen peroxide (H2O2) and singlet oxygen ( O2). Molecular oxygen itself has two unpaired electrons, so strictly speaking it is also a radical, but the reactivity of O2 is limited due to the fact that the two...

Follicular Cells Synthesize Iodinated Thyroglobulin

The iodination of thyroglobulin is catalyzed by the enzyme thyroid peroxidase, which is bound to the apical membranes of follicular cells. Thyroid peroxidase binds an iodide ion and a tyrosine residue in the thyroglobulin precursor, bringing them in close proximity. The enzyme oxidizes the iodide ion and the tyrosine residue to shortlived free radicals, using hydrogen peroxide that has been generated within the mitochondria of follicular cells. The free radicals then undergo addition. The product formed is a monoiodotyrosine (MIT) residue, which remains in peptide linkage in the thyroglobulin structure. A second iodine atom may be added to a MIT residue by this same enzymatic process, forming a diiodotyrosine (DIT) residue (see Fig. 33.3). Iodinated tyrosine residues that are close together in the thyroglobulin precursor molecule undergo a coupling reaction, which forms the iodothyronine structure. Thyroid peroxidase, the same enzyme that initially oxidizes iodine, is believed to...

Glutathione Peroxidase

This is a tetrameric enzyme with identical subunits, each monomer containing one atom of selenium in the form of a selenocysteine residue. Non-selenium containing glutathione peroxidase enzymes have also been described (Ketterer and Meyer, 1989). Glutathione peroxidase is found both in the cytosol and the mitochondria, and catalyses the removal of hydrogen peroxide from the cell, converting reduced glutathione to oxidized glutathione in the process - thus being one of the key enzymes of the antioxidant system. Glutathione peroxidase can also terminate the chain reaction of lipid peroxidation by removing lipid hydroperoxides from the cell membrane.

Vitamins E and K and the Lipid Quinones Are Oxidation Reduction Cofactors

Vitamin E is the collective name for a group of closely related lipids called tocopherols, all of which contain a substituted aromatic ring and a long iso-prenoid side chain (Fig. 10-22a). Because they are hy-drophobic, tocopherols associate with cell membranes, lipid deposits, and lipoproteins in the blood. Tocopherols are biological antioxidants. The aromatic ring reacts with and destroys the most reactive forms of oxygen radicals and other free radicals, protecting unsaturated fatty acids from oxidation and preventing oxidative

Oxidative Stress in Mammalian Cells

Oxidative Stress Activates

Transcription factors that are exclusively activated by ROS, or those that selectively control expression of ROS-protective and repair enzymes, are slowly being identified. Much of this work has used different cell lines, indicating that ROS show cell type specificity with respect to transcription factors and their activation (Bonizzi et al., 1999). NFKappaB (NF-KB) was the first eukaryotic transcription factor shown to respond directly to oxidative stress, the oxidative stress being induced by hydrogen peroxide from which hydroxyl radicals were generated via Fenton chemistry (Schreck et al., 1991). However incubation with other ROS, e.g. superoxide, hydroxyl radical and NO donors, failed to activate NFKB. In other words NFKB is selectively mediated by peroxides in a fashion comparable to the bacterial activation of OxyR, and over-expression of either catalase or Cu Zn-SOD in cell lines induced either suppression or superinduction of NFKB respectively (Schmidt et al., 1995), while...

Box 163 The World Of Biochemistry

Citrate has a number of important industrial applications. A quick examination of the ingredients in most soft drinks reveals the common use of citric acid to provide a tart or fruity flavor. Citric acid is also used as a plasticizer and foam inhibitor in the manufacture of certain resins, as a mordant to brighten colors, and as an antioxidant to preserve the flavors of foods. Citric acid is produced industrially by growing the fungus Aspergillus niger in the presence of an inexpensive sugar source, usually beet molasses. Culture conditions are designed to inhibit the reactions of the citric acid cycle such that citrate accumulates.

Michela Zanetti Livius V dUscio Timothy E Peterson Zvonimir S Katusic and Timothy OBrien

Endothelial production of oxygen free radicals, especially superoxide anion (O2-), is an important mechanism of vascular dysfunction in hypertension. Overproduction of oxygen free radicals, mainly O2- occurs in human hypertension and in a wide variety of animal models. Thus, analysis of O2- generation represents a useful tool for identifying oxidative stress in hypertension. Among the methods used for O2- detection, the chemiluminescent probe lucigenin has been widely shown to be a useful method for detecting and quantifying the O2- formation. On the other hand, staining by the oxidative fluorescent probe dihydroethidine, which is freely permeable to cell membranes, is suitable to monitor in situ production of O2- and to provide a reliable marker of its intracellular presence. Dihydroethidine is oxidized in the presence of O2-to a fluorescent marker product, which is rapidly intercalated into DNA. Thus, nuclei are the primary fluorescent structures labeled. By simply incubating...

Metallothionein and associated systems


First, it turned out that metallothionein is induced not only by metal ions, but also by a variety of other stresses, including changes in redox state, oxidative stress and stress hormone signals. This suggests that the protein might be a member of the integrated stress response and has other roles as well. A function as a scavenger of free radicals is often suggested. Second, metal-lothionein should not be considered a single protein. Many organisms have more than one Mt gene the human genome has no less than 16 Mt genes. Most invertebrates investigated so far have two genes, one strongly inducible by cadmium and encoding a cadmium-binding protein, the other not inducible and encoding a copper-binding protein. The presence of a specific zinc-binding metallothionein in invertebrates is doubtful the copper- and cadmium-binding metallothioneins of Drosophila, nematodes, earthworms, and snails are not inducible by zinc. Third, other metal-chelating substances have been found this...

Coupling Between 02 Sensors and Regulators by Chemical Modifications

Supported by the finding that, similar to a typical response to hypoxia, treatment of healthy human volunteers with the antioxidant N-acetyl-cysteine (NAC) enhances the hypoxic ventilatory response (HVR) and blood erythropoietin concentration (40). Thus, NAC or its biochemical derivates, cysteine and glutathione, appear to mimic hypoxia. Furthermore, the proposal that H202 and derived ROS such as OH' can serve as mediators ofthe 02 signal was based on findings in HepG2 cells and carotid body preparations showing the presence of a low output oxidase which may be an NADPH oxidase isoform able to convert oxygen to superoxide and thus act as an oxygen sensor (33). Subsequently, Po2-dependent OH' production has been demonstrated in hepatoma cells and primary hepatocytes implicating that hypoxia is associated with decreased OH levels. The response to hypoxia can be mimicked under normoxia by the application of the OH' radical scavenger dimethyl thiurea (DMTU) which reduces OH' levels (20,...

Water Soluble Vitamins

Free radicals are highly reactive molecules that carry an unpaired electron. Such free radicals can damage tissues by removing an electron from, and thus oxidizing, other molecules. Vitamin C (a water-soluble vitamin) and vitamin E (a fat-soluble vitamin) function as antioxidants through their ability to inactivate free radicals. These vitamins may afford protection against some of the diseases that may be caused by free radicals.

Tissue Structure Alterations

In vivo experimental studies on swine intervertebral discs and in vitro tests on human discs with intradiscal administration of an O2-O3 mixture (at a concentration of 27 g mL) demonstrated dehydration of the fibrillary matrix of the nucleus pulposus that disclosed the collagen mesh network and regressive events of fragmentation and vacuole formation. Neuroangiogenesis was sometimes present, with mild hyperplasia of the chondrocytes in the matrix periphery. Such changes are thought to be due to the decomposition of ozone accompanied by the release of free radicals that act directly on the disc matrix or indirectly via proteolytic enzymes (Figure 19.4).

On Life Longevity Problems

Let us focus on the mitochondria of cells as an example. Like most manufacturing processes, this energy-production factory also produces toxic waste. The waste consists of excess electrons. Occasionally, those electrons do not crash into molecular oxygen and do make water. Instead, the electrons crash into other atoms creating molecules with unpaired electrons called free radicals. Free radicals are highly reactive and cause a lot of internal cellular damage. Oxygenated free radicals are also called ROS (Reactive Oxygen Species) molecules. Like a lot of industrial waste, ROS molecules can damage anything that they encounter in their way, including proteins, fats, RNA, and even DNA. On the other hand, there are the molecules that destroy free radicals, including vitamin E. They are called anti-oxidants. There is evidence 78 that in spite of anti-oxidants and some products of genes that destroy free radicals, ROS molecules damage DNA as we age. Similar processes take place not only in...

Dietary monounsaturated fat and cancer

The great interest during the past several decades on the relationship between diet and cancer derives from the large variations on rates of specific cancer among countries, coupled with the dramatic changes in the incidence of these conditions among populations emigrating to regions with different rates. Mediterranean populations are known to be partially protected against coronary heart disease and certain types of cancers (Trichopoulou and Critselis, 2004 La Vecchia, 2004). Their dietary habits with low intake of saturated and polyunsaturated fats together with the high intake of oleic acid, n-3 fatty acids, fibre and natural antioxidants have been proposed to explain this protection (Bingham and Riboli, 2004). Emerging data suggest that the strong protective associations reported for olive oil intake in dietary studies may be due to some other protective components. A multinational study carried out by Simonsen et al. (1998) in five European centres shows that the protective...

Cytochrome -c Is A Tunnel Protien

Bound in the membrane of phagocytic cells and are gp 91phox and p22-phox. When the enzyme is activated it is believed that various protien such as p40, p67, p47 Rap 1A, and p2 rac1 2 migrate to the membrane and attach in the manner shown in the diagram. An electron from the cofactor NADPH is trasferred to oxygen and NADP+ and H+ are produced. When this electron is transferred to molecular oxygen, it produces the free radical superoxide anion (O-). This avidly reacts with the free radical nitric oxide and produces peroxynitrite. If luminol is added the peroxynitrite or its carbon dioxide derivative reacts to produce blue light at 425 nm. It is known that the free radicals (NO and O-) have a high attraction for each other and, if found in sufficient quantity, they will produce substantial amounts of OONO- (Figure 26.7). This strong oxidant, peroxynitrite, attacks all the major biochemical entities, namely, carbohydrates, lipids, proteins, enzymes, and nucleic acids DNA and RNA. Some...

Hereditary Hyperferritinaemia Cataract Syndrome

However, mutations in the IRE of the ferritin L subunit mRNA and its gene have been found to be associated with an unusual autosomal dominant disorder, first described in 1995 in two families, one French and one Italian, as the Hereditary Hyperferritinaemia-Cataract Syndrome (HHCS) (Girelli et al., 1995a,b Bonneau et al., 1995). The condition is characterized by the combination of congenital bilateral cataract and marked elevation of serum ferritin levels ( 1000 g l). The hyperfer-ritinaemia was found not to be related to iron overload and entirely due to the increase of the L-subunit, as determined by subunit-specific immunoassay. It was clearly distinguishable from genetic haemochromatosis because of (i) dominant transmission (ii) lack of any relation with HLA, and (iii) normal to low serum iron and transferrin saturation without evidence of parenchymal iron overload. When patients with the syndrome are subjected to unnecessary phlebotomies, they rapidly develop iron-deficient...

Functions of Essential Minerals and Vitamins

Nucleoprotein synthesis Vitamin C (Ascorbic acid) vital to collagen formation, serves as an important antioxidant Vitamin D (Calciferol) increases calcium absorption from gut, bone and tooth formation Vitamin E (Tocopherol) maintains pregnancy in mammals serves as an important antioxidant Vitamin K (Naphthoquinone) required for synthesis of a protein necessary for blood clotting Biotin coenzyme for enzymes associated with protein synthesis Folic acid required for nucleoprotein synthesis

Hormone Replacement Therapy

Hormone Replacement Progress

Postmenopausal hormone replacement therapy has been suggested to reduce cardiovascular morbidity by up to 56 in healthy women who take estrogen compared to women who have never taken hormone replacement medications (56) however, these observations from small clinical trials may overestimate the actual cardiovascular benefits derived from hormone replacement therapy (Fig. 6). Theoretically, estrogen supplementation may reduce coronary events by improving cholesterol profiles, promoting endothelium-derived vasodilation, and by serving as an antioxidant (12,57-59). Despite these potential therapeutic benefits, the HERS trial failed to demonstrate the therapeutic efficacy of estrogen replacement therapy compared to placebo with respect to coronary heart disease, nonfatal myocardial infarction, or mortality at 5 yr follow-up (60). In fact,

Miscellaneous Forms of Therapy

For patients who have severe intolerable dyspnea, and are unresponsive to other treatment, opiates, such as hydrocodone and morphine, may improve their symptoms (28). These agents must be used with great care because of their potential side effects. Antioxidant therapy Lung damage from oxidants has been proposed as a mechanism for the development of COPD. There are reports suggesting the use of antioxidants, such as vitamin C, vitamin E, and -carotene, for lung protection and treatment of this disease (29). Further studies and additional evidence are required before these are routinely recommended. Noninvasive ventilatory support

Other Agents under Trial

Other agents under investigation in colorectal chemoprevention include difluoromethylornithine (DFMO), which irreversibly inhibits ornithine decarboxylase and blocks cell proliferation. Ursodeoxy-cholic acid reduces the concentration of the secondary bile acid deoxycholic acid in the colon and affects arachidonic acid metabolism 9-11 . 3-hydroxy-3-methylglutaryl Coenzyme A reductase inhibitors are usually used in the setting of lowering cholesterol but also have antioxidant anti-inflammatory properties and inhibit cell proliferation 12 . Preclinical work in mutant APC murine models have shown that sulin-dac in combination with EGFR inhibitor EKI-785 can decrease intestinal polyps 13 . Almost one-half the mice treated with the combination agents did not develop polyps. With the recent success of beva-cizumab, an antibody to the VEGF-receptor in metastatic colorectal cancer, and cetuximab, an antibody to EGFR, further strategies will be applied to prevention.

Intracellular Iron Storage

We have pointed out in an earlier chapter that while nearly all forms of life require iron, the element has unfavourable chemical properties that lead to the formation of insoluble ferric-hydroxide polymers and toxic free radicals. After dealing with the transport components involved in moving iron between cells and into cells, we now come to the storage forms of iron within cells, that sequester the metal in a non-toxic and bioavailable form. Historically, the first of these to be observed within mammalian cells was haemosiderin, which was identified histologically as iron-rich granules in tissues, that gave an intense Prussian blue reaction with potassium ferrocyanide (Perls, 1867). It was first isolated by Cook (1929) and described as consisting of 'organic granules impregnated with some form of ferric oxide'. It is insoluble, visible by light microscopy as golden-yellow intracellular granules and is localized in membranous structures termed siderosomes (Richter, 1978), which...

ROS and Hypoxic Pulmonary Vasoconstriction

Increase in ROS generation occurs during hypoxia. Data do support this model i) pharmacological antioxidants have been shown to block the hypoxic response in isolated buffered perfused lung suggesting an increase in ROS is required (32) ii) inhibition of CuZn-SOD to block hydrogen peroxide formation has been shown to abrogate HPV, suggesting that hydrogen peroxide is an important downstream signaling agent iii) Inhibition of catalase augments the HPV response (22) and iv) hydrogen peroxide constricts the pulmonary circulation in normoxia (31). Taken together, this suggests that increased hydrogen peroxide is the signaling molecule involved in HPV. Unfortunately, experiments opposing both models have been reported, thus the role of ROS and the mechanism involved in sensing oxygen in HPV remains unresolved.

Knox Van Dyke Contents

The concept of oxidative stress (OS) is attributed to the German scientist Helmut Seis.1 OS occurs when there is a higher concentration of oxidants than of the opposing antioxidants, i.e., there is a shift in the ratio of oxidants to antioxidants to greater than 1. Basically, our body uses oxygen for the maintenance of life. Oxygen is used in the oxidation of carbohydrates to create energy to live and in the creation of oxidized lipids and nucleic acids to produce the four bases that form the code of life. Substances that protect us from infection are derived from oxygen molecules in one form or another. However, utilization of oxygen produces a long-term risk. This risk is related to attack on our cellular macromolecules, e.g., protein, DNA, RNA, and lipid, from the myriad of different oxygen-linked substances. Some of these are quite toxic depending on the form of oxygen and the atoms linked to it, which create new and possibly more toxic compounds. For example, oxygen can exist in...

Target cell sensitivity

That has been shown to exert direct toxic effects against neoplastic but not normal cells and to cause either lysis or growth inhibition of both autologous and heterologous tumour cells. The mechanism of TNFa cytotoxicity is at least partially mediated through generation of ROS. The susceptibility of a cell to killing by TNFa may be influenced by its content of antioxidant enzymes that specifically detoxify ROS to prevent cellular damage, such as catalase, superoxide dismutases (SOD), and glutathione peroxidase. SOD (CuZnSOD and MnSOD) are metalloproteins that participate in the inactivation of free oxygen radicals reducing superoxide to H202 and protecting cells from oxidative damage, whereas catalase and glutathione peroxidase scavenge H202. Several studies have shown that exposure to TNFa induces cells to synthesize MnSOD, which is essential for cellular resistance to TNFa toxicity. However, a wide spectrum of human and murine tumour cells fail to make the enzyme in response to...

Materials And Methods

Blood samples from healthy normolipidemic middle-aged volunteers were analyzed. Exclusion criteria were the intake of antioxidants such as probucol or a supplementation with vitamins A or E. The subjects had given their written consent, and the study protocol was approved by the Ethics Committee of the Medical Faculty Dresden.

Complement and Ocular Diseases

Other risk factors for the development of AMD include family history and smoking. Single nucleotide polymorphism variants of the genes for factors H and B, as well as LOC387715 24 , are associated with a 10.3-fold increased risk for the development of subretinal neovascularization in individuals with a sibling with exudative AMD. A positive family history also carries an important risk factor for non-exudative AMD. For example, the odds of developing RPE atrophy increases 8.2 times with a positive history in a sibling 25 . Smoking may effect the incidence of AMD via a reduction in macular carotenoids 26 , adverse effects on RPE drug detoxification mechanisms, or a decrease in choroidal blood flow and antioxidant levels 27, 28 .

Oxidative Stress in Bacteria

The genetic response to oxidative stress has been studied extensively in E. Coli. The synthesis of over 80 proteins is induced upon exposure to H2O2 and O -, and two transcription factors have been identified. Firstly the system OxyR which is activated by H2O2, resulting in the formation of an intracellular disulfide bond, that then switches on several genes encoding for antioxidant functions such as catalase. During aerobic growth, OxyR acts homeostatically to regulate cellular H2O2 levels. Secondly the transcription factors SoxR S are induced by superoxide anions or nitric oxide and activate expression of genes, the products of which are involved either in protection from oxidative stress or repair of ROS-mediated damage. The SoxR protein is activated by oxidation of its 2Fe-2S component and stimulates the SoxS gene. The SoxS protein then induces transcription of at least 15 genes encoding antioxidant functions, e.g. SOD, metabolic functions and antibiotic resistance by activation...

The respiratory burst

Interaction between superoxide and hydrogen peroxide leads to the formation of the hydroxyl anion or radical. All molecules with unpaired electrons are called free radicals. They are highly unstable and are capable of damaging proteins, lipids, DNA and cell membranes. Thus, they may be responsible for the destruction of phagocytosed microorganisms. Normally, endogenous, scavenger, enzymes (e.g. superoxide dismutase, catalase, glutathione peroxidase) destroy free radicals and hydrogen peroxide. However, in activated phagocytes they are produced in greater quantities than can be destroyed allowing them to accumulate and indeed to be secreted by the cells. Although the oxygen radicals are extremely short lived, superoxide and H2O2 are released in the tissues their persistence (and hence the degree of resulting tissue damage) depends on the ability of the cells in the locality to destroy them. In addition to these toxic oxygen metabolites, other microbicidal...


Oxidized molecules accumulate in atheroma, often in association with an undersupply of antioxidants in the microenvironment 59 , 35 . The excess of oxidants in vascular cells puts an 'oxidative stress' on the vessel wall which promotes atherosclerosis by impairing endothelial cell function and oxidizing LDL 59 , 35 .

Lifestyle Factors

Another important lifestyle factor that contributes to CHD risk is diet, particularly high intake of saturated fat (Hooper et al. 2001) and low intake of fiber or unsaturated fats (Kromhout 2001 Pereira and Pins 2000). Data from the Framingham Heart Study accrued over 50 years have clarified the importance of a balanced diet as a preventive measure for CHD (Millen and Quatromoni 2001). A comprehensive dietary intervention study performed in Finland aimed at cardiovascular disease risk reduction by altering the type of fats consumed, lowering sodium intake, and increasing vegetable and fruit consumption achieved dramatic reductions in cardiovascular mortality during the period 1972-1997, along with significant improvements in blood pressure and serum cholesterol levels (Piet-inen et al. 2001). Although antioxidants are quite popular as health care supplements, there is no convincing evidence that either vitamin E, caro-tenoids, or vitamin C protect against CHD. Multiple studies seem to...

AOS as a Mediator

AOS from mitochondria and other cellular sources have been traditionally regarded as toxic by-products of metabolism with the potential to cause damage to lipids, proteins, and DNA. To protect against the potentially damaging effects of AOS, cells possess several isoforms of the antioxidant enzyme as superoxide dismutase (SOD which reduces 02 to H202), as well as catalase (which reduces H202 to HjO and 02). Thus, oxidative stress may be broadly defined as an imbalance between oxidant production and the antioxidant capacity of the cell to prevent oxidative injury. Oxidative stress has been implicated in a large number of human diseases including atherosclerosis, pulmonary fibrosis, cancer, neurodegenerative diseases and aging (29). Yet the relationship between oxidative stress and pathobiology of these diseases is not clear, largely due to a lack of understanding of the mechanisms by which AOS function in both physiological and disease states. facilitated by higher concentrations of...

Loo No Roono

Antioxidant Defense Mechanisms Cellular antioxidant defenses can be separated into two types, enzymatic and non-enzymatic. Enzymatic defense systems include superoxide dismutase, glutathione peroxidases, and catalases. The non-enzymatic pathways include vitamin E, vitamin C and P carotene.

Ch3 Ch3

Vitamin E as an antioxidant Until the last decade of the twentieth century, almost all interest in vitamin E was concerned with its putative role as a natural antioxidant. a-Toco-pherol is present in the lipid bilayers of biological membranes (Section 6.5) and may play a structural role there. However, its main function is thought to be the prevention of the oxidation of the unsatu-rated lipids present in the membrane (Section 2.3.4 and Box 4.3). The products of lipid peroxidation can cause damage to cells if the oxidative process is not kept in check (Box 4.3). Such damage appears to be exacerbated in animals fed diets deficient in vitamin E. a-Tocopherol primarily acts as a terminator of the lipid peroxidation chain reactions by donating a hydrogen atom to a lipid radical (Section 2.3.4). The resulting tocopheryl radical is relatively unreactive and unable to attack adjacent unsatu-rated fatty acids because the unpaired electron becomes delocalized in the aromatic ring structure....


Are highly susceptible to peroxidation unless adequate vitamin E is available as an antioxidant. When diets that contain high levels of n-3 PUFA from fish oils are given, some diminution in the concentration of plasma vitamin E may be observed. This is because such diets contain relatively low levels of vitamin E. Concomitantly, some increase in the concentration of the products of lipid peroxidation may be measured in the plasma. Such changes do not occur when the sources of n-3 PUFA are plant oils, because they are richer in vitamin E than fish oils. There is limited evidence that the marked suppression by n-3 PUFA of lymphocyte proliferation in response to antigens or non-specific mitogens, does not occur when the diet is supplemented with vitamin E. Functions such as neutrophil phagocytosis are suppressed by vitamin E deficiency and enhanced by vitamin E supplementation. However, vitamin E supplementation decreases bactericidal activity, probably because such activity is promoted...

Future perspectives

The ecophysiology of supra- and eulittoral species needs to be investigated in more detail in field studies. To survive in the intertidal zone, algae need to protect their metabolism and particularly their photosynthetic apparatus against temporary light stress conditions, heat stress, cold, freezing and also against pollution. Virtually nothing is known about protective mechanisms in polar seaweeds. Therefore, a detailed analysis of such mechanisms ensuring homeostasis and functional integrity of the photosynthetic apparatus in supra-and eulittoral polar seaweeds is necessary. Changes in the expression of photo-synthetic key proteins (D1, RubisCO, ATP-synthase), and the synthesis of specific protective proteins (Heat Shock Proteins, Chaperonins, Cryoproteins) and protective metabolites (osmo-lytes, cryoprotectants, antioxidants, sunscreens etc.) in relation to stress exposure should be studied in the field, mesocosms and controlled laboratory experiments. So far, gene expression,...


Laminar flow exposure leads to activation of antioxidant genes in endothelial cell (EC) (21 jand promotes EC survival and quiescence and the secretion of substances that promote vasodilation and anticoagulation (22). Flow induces an increase in oxidative stress in EC, which is dependent on the pulsatile nature of flow (23).


It can be concluded that CL methods were confirmed to be a very useful tool for the assessment of phagocyte-generated ROS and of the total radical-trapping antioxidant parameter of plasma (serum) as markers of oxidative stress induced by ischemia reperfusion of organs and tissues. Information on the intensity of ROS production and on the total peroxyl radical-trapping potential is of great importance in other pathophysiological conditions as well, because it provides basic data needed when indicating proper anti-inflammatory and antioxidative therapy, thus preventing oxidative damage to organs and tissues with serious clinical consequences.

Therapy Concepts

Significant lesion growth has been observed following successful reperfusion of the ischemic territory. Reperfusion damage is largely attributed to the high levels of oxygen free radicals, probably due to the fact that radical trapping mechanisms, for example, via superoxide dismutase activity have been downregulated during the ischemic episode. Administration of radical scavenging compounds (e.g., ascorbic acid) should lower the levels of reactive oxygen radicals and thereby the disastrous consequences thereof. In fact, administration of the free radical

Glutathione GSH

Glutathione (GSH), the tripeptide g-glutamylcysteinyl glycine, can exist both in a reduced and an oxidized form (the latter composed of two GSH molecules linked by a disulfide bridge). It is one of the most important cellular antioxidants since it supplies the electrons for the reduction of peroxides by the action of glutathione peroxidase. The oxidized glutathione GSSH formed is subsequently regenerated by the NADPH dependent glutathione reductase. Inside the cell, glutathione is present in millimolar concentrations mainly in the reduced form, GSH small changes in the ratio of reduced GSH to oxidized GSSG may have significant biological effects. GSH GSSG ratios vary enormously between intracellular compartments, being the highest in the nucleus 100 1 and lowest in the endoplasmic reticulum (Hwang


Previous studies have established that birds have higher concentrations of antioxidants in their bodies and appear more efficient in dealing with the oxidative stress compared to mammals.3'27 Iqbal et al.12'13 hypothesized that uric acid plays an important role in limiting oxidative stress and subsequent accumulation of advanced glycosylation end products (AGEs), such as Ps in birds. In previous studies, dose rates of allopurinol from 2 to 50 mg kg were used in laboratory rats,28


Even passive smoking has been shown to increase experimental atherosclerosis (133). Exposure of healthy nonsmoking subjects to passive smoking, in a follow-up study, caused an acute decrease in serum ascorbic acid levels and antioxidant defense, decreased LDL capacity to resist oxidation, increased serum levels of lipid peroxidation end products, and LDL isolated from these subjects was taken up by cultured macrophages at an increased rate (134). Secondhand smoke also caused endothelial dysfunction and increased adrenergic responsiveness (which was abolished by inhibition of NOS and removal of endothelium) and atherosclerosis in hypercholesterolemic rabbits. These effects were mitigated by l-arginine supplementation (135).

Haem Oxygenase

Haem oxygenase, HO-1 (also referred to as heat shock protein (hsp) 32) is a highly inducible stress protein that oxidatively cleaves haem molecules (derived from haemoglobin, cytochromes, etc.) to the bile pigments, biliverdin and bilirubin, together with the gaseous cellular messenger carbon monoxide and Fe2+. Ferris et al. (1999) suggested that HO-1 augmented iron efflux thereby modulating intracellular iron levels. The induction of HO-1 is reputed to be a protective event transition metal ions and oxidative stress can induce its transcription. Several authors have suggested that HO-1 confers cellular protection against a wide range of oxidant stresses both in vivo and in vitro, but the mechanism of protection is unclear. Neither bilirubin or biliverdin have strong antioxidant properties, particularly in vivo, while the production of free iron could be considered to be a prooxidant event. Some authors suggest that this free redox-active iron could induce ferritin synthesis, hence an...

Cancer Cells

Interestingly, the activity of some cytoprotective enzymes, particularly catalase and glutathione peroxidase, is low in animal and human cancers, suggesting that most cancer cell types cannot detoxify hydrogen peroxide, this reactive oxygen intermediate being an important secondary messenger for the stimulation of various pathways. Whether this reflects utilization or poor upregulation is unknown. Furthermore it is reported that all cancer cells have some imbalance in antioxidant enzyme levels by comparison with their cells of origin (Oberley and Oberley, 1997).


In these experiments, we used several plant-derived extracts as the source of antioxidants. We obtained dried powders of pine bark and hawthorn berry from the Montiff (Beverly Hills, CA). Green tea extract (Natural Brand) was purchased at a local General Nutrition Center (GNC) store. Potassium superoxide was obtained from Aldrich Chemicals (Milwaukee, WI). Potassium superoxide (KOS) solution was made by taking 45 mg KOS and dissolving it in 5 ml of phosphate-buffered saline (PBS) buffer. It is kept on ice prior to use. The NG in 0.6-mg tablets was obtained from Parke, Davis & Co. (Detroit, MI).

Ageing of Cells

The ageing of cells is associated with the loss of ability of the cell to maintain a variety of factors that include iron homeostasis and metabolic rate, so that the cell is more vulnerable to ROS, the net result being increased oxidative stress. In general there are significant decreases in the glutathione redox index with increasing age in both the heart and the liver (Stio et al., 1994). Other factors are also involved, including increase in iron content, decrease in antioxidant protection and over-expression of certain cytoprotective enzymes, for instance MnSOD is ageing brain - although the mechanisms mediating such upregulation are unknown. Generation of ROS by electrons escaping from the electron transport chain in mitochondria is by far the predominant process during the lifetime of a normal healthy cell. Mitochondrial malfunction has been suggested as the intracellular basis of ageing. There is also clear evidence that free-radical dependent reactions lead to lipofuscin...

Emerging Data

Antioxidants (especially vitamin E)i0 Antioxidants prevent plaque-forming effects of free radicals and may slow progression of plaques High fiber diets are lower in fat and cholesterol Water-soluble fibers may enhance the excretion of bile Dose to establish effect is unclear. Eating generous amounts of fruits and vegetables will optimize natural antioxidant sources 10. Stephens NG. Parsons A. Schofield PM. et al. Randomised controlled trial of vitamin E in patients with coronary disease Cambridge Heart Antioxidant Study. Lancet 1996 347 781-6.


Such sequences are present in the promoters of both phase I and phase II genes. Genes activated by the Ah receptor are jointly referred to as the Ah battery (Nebert et al. 2000). The group involves at least two P450 genes (Cyp1a1 and Cyp1a2) and four genes involved with phase II biotransformation and the antioxidant stress response. Interestingly, the promoters of phase II biotransformation enzyme genes in the Ah battery contain not only xenobiotic-responsive elements but also AREs. generated by P450 activity are very electrophilic, which means that they react easily with other compounds to compensate their shortage of electrons. Electrophiles and oxygen radicals induce antioxidant enzymes by the mechanisms discussed above. The presence of AREs in the promoters of phase II biotransformation enzymes ensures that these genes are also induced. The chronic toxicity of compounds such as dioxin is ascribed to a situation of sustained oxidative stress in the whole organism. Figure 6.9...


There is massive accumulation of iron in the tissues of thalassaemia patients primarily as a result of the influx of excessive haem breakdown both from the use of regular blood transfusions to correct the anaemia, and the increased breakdown of the erythrocytes as a result of the compromised status of the erythrocytes due to the imbalance in globin synthesis. In addition, iron absorption is increased as a result of the underlying anaemia. Splenectomy is often required because of the increased susceptibility of the patient to infection, resulting in even higher iron loading. The antioxidant status of such individuals is compromised, e.g. vitamin E and beta carotene levels are lower than controls while LDL conjugated dienes are three times higher than controls. This could lead to oxidative modification of low-density lipoprotein and an increased atherogenetic risk in beta thalassaemia patients.

Other Diseases

This chapter is designed to introduce you to our understanding of the immune mechanisms involved in atherosclerosis and cancer. A strange combination Perhaps, except in recent years our understanding of the molecular processes involved in these diseases has grown enormously and has demonstrated a clear similarity between them. Atherosclerosis is a disease affecting the large arteries of the body. It is characterised by proliferation of the smooth muscle cells of the arterial wall and the formation of a fatty streak. Evidence suggests that this characteristic lesion may be initiated by mutation of transformation of a single smooth muscle cell (SMC) (as a result of a chemical or infectious insult) leading to the clonal expansion of the cell. With extrapolation, this matches the clonal expansion hypothesis of carcinogenesis. Both diseases are characterised by tissue damage caused by the production of oxygen and nitrogen-derived free radicals as a result of oxidative stress. A wide range...

Lipoprotein Uptake

In addition to LPL, macrophages secrete oxygen-free radicals, proteases, and Apo E, all of which affect lipoprotein accumulation (350,353). In the ARIC study, Apo E epsilon 2 3 was associated with carotid atherosclerosis, probably through delayed clearance of TG-rich lipoproteins (367). Apo E-deficient mice develop hyperlipidemia and atherosclerosis, and the lipoprotein oxidation occurs in macrophage-rich areas in early lesions. However, in necrotic areas of advanced lesions oxidation occurs diffusely in the extracellular areas (368). Physiologic levels of Apo E in the vessel wall are antiatherogenic in conditions of severe hyperlipidemia, and can affect later stages of plaque development (369).