For a long time, superoxide generation by an NADPH oxidase was considered as an oddity only found in professional phagocytes. Over the last years, six homologs of the cytochrome subunit of the phag...

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The NOX Family of ROS-Generating NADPH Oxidases: Physiology and Pathophysiology

Acute kidney injury (AKI) is a complex disorder for which currently there is no accepted definition. Having a uniform standard for diagnosing and classifying AKI would enhance our ability to manage these patients. Future clinical and translational research in AKI will require collaborative networks of investigators drawn from various disciplines, dissemination of information via multidisciplinary joint conferences and publications, and improved translation of knowledge from pre-clinical research. We describe an initiative to develop uniform standards for defining and classifying AKI and to establish a forum for multidisciplinary interaction to improve care for patients with or at risk for AKI. Members representing key societies in critical care and nephrology along with additional experts in adult and pediatric AKI participated in a two day conference in Amsterdam, The Netherlands, in September 2005 and were assigned to one of three workgroups. Each group's discussions formed the basis for draft recommendations that were later refined and improved during discussion with the larger group. Dissenting opinions were also noted. The final draft recommendations were circulated to all participants and subsequently agreed upon as the consensus recommendations for this report. Participating societies endorsed the recommendations and agreed to help disseminate the results. The term AKI is proposed to represent the entire spectrum of acute renal failure. Diagnostic criteria for AKI are proposed based on acute alterations in serum creatinine or urine output. A staging system for AKI which reflects quantitative changes in serum creatinine and urine output has been developed. We describe the formation of a multidisciplinary collaborative network focused on AKI. We have proposed uniform standards for diagnosing and classifying AKI which will need to be validated in future studies. The Acute Kidney Injury Network offers a mechanism for proceeding with efforts to improve patient outcomes.

Acute Kidney Injury Network: report of an initiative to improve outcomes in acute kidney injury

The goal of this review is to present a comprehensive survey of the many intriguing facets of creatine (Cr) and creatinine metabolism, encompassing the pathways and regulation of Cr biosynthesis an...

http://www.afboard.com/library/creatinemetabolism.pdf

Creatine and Creatinine Metabolism

Free radicals and other reactive species (RS) are thought to play an important role in many human diseases. Establishing their precise role requires the ability to measure them and the oxidative damage that they cause.


This article first reviews what is meant by the terms free radical, RS, antioxidant, oxidative damage and oxidative stress.


It then critically examines methods used to trap RS, including spin trapping and aromatic hydroxylation, with a particular emphasis on those methods applicable to human studies.


Methods used to measure oxidative damage to DNA, lipids and proteins and methods used to detect RS in cell culture, especially the various fluorescent ‘probes' of RS, are also critically reviewed.


The emphasis throughout is on the caution that is needed in applying these methods in view of possible errors and artifacts in interpreting the results.





Keywords: Cell culture, free radical, reactive species, antioxidant, oxidative stress, oxidative damage, fluorescent probe, lipid peroxidation, superoxide


Introduction
Free radicals and other ‘reactive oxygen (ROS)/nitrogen/chlorine species' (for an explanation of these terms see Table 1) are widely believed to contribute to the development of several age-related diseases, and perhaps, even to the aging process itself (Halliwell & Gutteridge, 1999; Sohal et al., 2002) by causing ‘oxidative stress' and ‘oxidative damage' (terms explained in Table 2). For example, many studies have shown increased oxidative damage to all the major classes of biomolecules in the brains of Alzheimer's patients (Halliwell, 2001; Butterfield, 2002; Liu et al., 2003). Other diseases in which oxidative damage has been implicated include cancer, atherosclerosis, other neurodegenerative diseases and diabetes (Hagen et al., 1994; Chowienczyk et al., 2000; Halliwell, 2000a, 2001, 2002a, 2002b; Parthasarathy et al., 2000). If oxidative damage contributes significantly to disease pathology (Table 3 lists the criteria needed to establish this), then actions that decrease it should be therapeutically beneficial (Halliwell, 2001; Lee et al., 2002a; Liu et al., 2003). If the oxidative damage is involved in the origin of a disease, then successful antioxidant treatment should delay or prevent the onset of that disease (Halliwell, 1991, 2002a, 2002b; Galli et al., 2002; Steinberg & Witztum, 2002). To establish the role of oxidative damage (Table 3), it is therefore essential to be able to measure it accurately. For example, the failure of interventions with antioxidants such as vitamin E, β-carotene or ascorbate to decrease disease incidence in several human intervention trials may have simply been due to the failure of these compounds to decrease oxidative damage in the subjects tested (Halliwell, 1999a, 2000c; Levine et al., 2001; Meagher et al., 2001). In this review, we will examine the methods available to measure reactive species (RS) and oxidative damage, with a particular emphasis on those applicable to human studies.



Table 1

Nomenclature of reactive species





Table 2

Some key definitions





Table 3

Criteria for implicating RS as a significant mechanism of tissue injury in human disease




Measuring RS in vivo: basic principles

Some fascinating techniques such as L-band electron spin resonance (ESR) with nitroxyl probes and magnetic resonance imaging spin trapping are under development to measure RS directly in whole animals (e.g. Berliner et al., 2001; Han et al., 2001; Utsumi & Yamada, 2003), but no probes are currently suitable for human use. Most RS persist for only a short time in vivo and cannot be measured directly. There are a few exceptions: examples include H2O2 (discussed below), and perhaps, NO•, in the sense that serum levels of NO2− have been claimed to measure vascular endothelial NO• synthesis (Kelm et al., 1999), despite the fact that NO2− is quickly oxidized to NO3− in vivo (Kelm et al., 1999; Oldreive & Rice-Evans, 2001). Essentially, there are two approaches to detecting transient RS: 


attempting to trap these species and measure the levels of the trapped molecules and


measuring the levels of the damage done by RS, that is, the amount of oxidative damage.




Sometimes other approaches are used. They include measurements of erythrocyte antioxidant defences and of total antioxidant activity of body fluids; falls in these parameters are often taken as evidence of oxidative stress. Erythrocytes cannot synthesize proteins, however, and their antioxidant enzyme levels may drop as they ‘age' in the circulation (Denton et al., 1975). Thus changes in their levels are more likely to reflect changes in the rates of red blood cell turnover: if this slows down, the circulating erythrocytes will be older on average and so levels of antioxidant enzymes in them will appear to fall. Vice versa, if an intervention accelerates red cell removal or increases erythropoiesis, levels of antioxidants in red cells will seem to rise. Hence, such data should be interpreted with caution.

Depending on the method that is used to measure it, the plasma or serum ‘total antioxidant capacity' (TAC) usually involves major contributions from urate, ascorbate and sometimes albumin −SH groups (Benzie & Strain, 1996; Halliwell & Gutteridge, 1999; Prior & Cao, 1999; Rice-Evans, 2000; Bartosz, 2003), although different methods measure different things (Schlesier et al., 2002; Bartosz, 2003). Thus, for example, if plasma albumin levels fall, TAC will fall. If urate levels rise, TAC will rise. The multiple changes in blood chemistry that occur in sick people mean that TAC changes should be interpreted with caution. TAC is also influenced by diet, often because consumption of certain foods may produce changes in plasma ascorbate and/or urate levels (Halliwell, 2003b).

/pdf/measuring-reactive-species-and-oxidative-damage-in-vivo-and-5a9iiwcjlt.pdf

Measuring reactive species and oxidative damage in vivo and in cell culture: how should you do it and what do the results mean?

Free radical production occurs continuously in all cells as part of normal cellular function. However, excess free radical production originating from endogenous or exogenous sources might play a role in many diseases. Antioxidants prevent free radical induced tissue damage by preventing the formation of radicals, scavenging them, or by promoting their decomposition. This article reviews the basic chemistry of free radical formation in the body, the consequences of free radical induced tissue damage, and the function of antioxidant defence systems, with particular reference to the development of atherosclerosis.

https://jcp.bmj.com/content/jclinpath/54/3/176.full.pdf

Antioxidants in health and disease

Calprotectin (CLP) belonging to the S-100 protein family is a heterodimeric complex (S100A8/S100A9) formed by two binding proteins. Upon cell activation, CLP stored in neutrophils is released extracellularly in response to inflammatory stimuli and acts as damage-associated molecular patterns (DAMPs). S100A8 and S100A9 possess both anti-inflammatory and anti-bacterial properties. The complex is a ligand of the toll-like receptor 4 (TLR4) and receptor for advanced glycation end (RAGE). At sites of infection and inflammation, CLP is a target for oxidation due to its co-localization with neutrophil-derived oxidants. In the heart, oxidative stress (OS) responses and S100 proteins are closely related and intimately linked through pathophysiological processes. Our review summarizes the roles of S100A8, S100A9 and CLP in the inflammation in relationship with vascular OS, and we examine the importance of CLP for the mechanisms driving in the protection of myocardium. Recent evidence interpreting CLP as a critical modulator during the inflammatory response has identified this alarmin as an interesting drug target.

/pdf/involvement-of-oxidative-stress-in-protective-cardiac-1hwx027x.pdf

Involvement of Oxidative Stress in Protective Cardiac Functions of Calprotectin

We investigated the influence of PUFA in phospholipids (PL) on the functional characteristics of cultured cardiomyocytes (CM) in basal conditions and during free radical (FR) stress provoked either by the xanthine/xanthine oxidase (X/XO) system or by a (9Z, 11E, 13 (S), 15Z)-13-hydroperoxyoctadecatrienoic acid (13-HpOTrE). CM were grown in media containing either n - 3 (eicosapentaenoic acid, EPA, and docosahexaenoic acid, DHA) or n - 6 (arachidonic acid, AA). These two groups of CM displayed different PUFA n - 6/n - 3 ratio in PL. However, their basal electromechanical characteristics were similar. The X/XO system drastically altered CM functions, without difference between the two groups of CM. 13-HpOTrE caused a moderate and reversible depression in action potential parameters, which was dependent upon the PL PUFA, since the n - 3-enriched CM exhibited an earlier functional depression but faster recovery. Thus, the peroxidative damage of CM depended on a cross relationship between FR species and the PL PUFA composition.

Dependence on the phospholipid polyunsaturated fatty acids of the oxidative injury of isolated cardiomyocytes.

Cardiovascular manifestations in acute poisoning by antidepressive agents. Discussion and review of the literature

Antioxidants and Diabetes

In order to establish the possible existence of a cardiac converting enzyme and its role in the pathophysiology of the myocardial ischemia, the direct cardiac effects of IEC and AI or AII were studied on the isolated rat heart perfused through the left atria. Three series of seven hypertensive rats (SHR) were used. The reduction of the aortic flow (QAO) due to ischemia (produced by a left coronary artery ligation of 10 mn) was brought into line with the reduction of the coronary flow (QCORO) and the weight of the heart. This reduction was 2.06 +/- 1.8 for the control, 1.96 +/- 1.27 when captopril (CAP) (10(-5) M) was added to the perfusion liquid and 1 +/- 0.42 when perindopril (PER) (1.2 x 10(-5) M) was added to the perfusion liquid (p less than 0.05 vs CAP). Four series of 10 rat hearts (Sprague Dawley) were used to study the changes on the working heart caused by short perfusions of AI or AII (10(-7) M) in the presence of IEC or saralasin (SAR 10(-7) M). AII caused a reduction of the QCORO of 2.1 +/- 0.26 ml/mn, an increase of the QAO of 2.5 +/- 0.9 ml/mn and an increase of the heart rate (HR) of 9 +/- 3.24 beats/mn. In the presence of CAP or PER the effects of AII were the same, however in the presence of SAR these effects were prevented. AI caused a reduction of the QCOR of 2.5 +/- 0.4 ml/mn, an increase of the QAO of 2.5 +/- 0.8 ml/mn and an increase of the HR of 18 +/- 4 beats/mn.(ABSTRACT TRUNCATED AT 250 WORDS)

Direct cardiac effects of angiotensins I and II and 2 converting enzyme inhibitors (captopril and perindopril). Indirect demonstration of a converting enzyme in the rat heart

Luc Rochette

Papers

Involvement of Oxidative Stress in Protective Cardiac Functions of Calprotectin

Dependence on the phospholipid polyunsaturated fatty acids of the oxidative injury of isolated cardiomyocytes.

Cardiovascular manifestations in acute poisoning by antidepressive agents. Discussion and review of the literature

Antioxidants and Diabetes

Direct cardiac effects of angiotensins I and II and 2 converting enzyme inhibitors (captopril and perindopril). Indirect demonstration of a converting enzyme in the rat heart