The antioxidant acetylcysteine reduces cardiovascular events in patients with end-stage renal failure: a randomized, controlled trial

Antioxidant therapy does not ameliorate oxidative stress and inflammation in patients with end-stage renal disease

Oxidative stress and inflammation are common manifestations and major mediators of cardiovascular and many other complications of end-stage renal disease (ESRD). Oxidative stress and inflammation are intimately interrelated as each can cause the other. The present study tested the hypothesis that antioxidant therapy may alleviate oxidative stress and improve inflammation in ESRD patients. We studied 37 hemodialysis patients, of whom 20 were treated daily with a combination of vitamin E, 800 lU; vitamin C, 250 mg; vitamin B6, 100 mg; vitamin B12, 250 microg; and folic acid, 10 mg; whereas 17 patients were given placebo for 8 weeks. Predialysis levels of f-2 isoprostane and protein carbonyl (markers of oxidative stress), C-reactive protein (CRP) and IL6 (markers/ mediators of inflammation) were measured prior to and at 4 and 8 weeks after the onset of therapy. Kt/V, predialysis and postdialysis blood pressure, blood hemoglobin, erythropoietin requirement, plasma ferritin and transferrin saturation, and nutritional indexes were similar among the 2 groups at baseline and remained virtually unchanged throughout the study period. Likewise, plasma f-2 isoprostane, protein carbonyl, CRP, and IL-6 levels remained unchanged and were unaffected by antioxidant administration. In conclusion, the addition of a potent antioxidant cocktail to conventional vitamin supplements had no effect on severity of ESRD-induced oxidative stress, inflammation, hypertension, anemia, or nutritional disorders in hemodialysis patients. Thus, high doses of vitamins beyond the routinely prescribed vitamin supplements do not appear to be indicated in this population.

Astaxanthin, oxidative stress, inflammation and cardiovascular disease

It is accepted that oxidative stress and inflammation play an integral role in the pathophysiology of many chronic diseases including atherosclerotic cardiovascular disease. The xanthophyll carotenoid dietary supplement astaxanthin has demonstrated potential as an antioxidant and anti-inflammatory therapeutic agent in models of cardiovascular disease. There have been at least eight clinical studies conducted in over 180 humans using astaxanthin to assess its safety, bioavailability and clinical aspects relevant to oxidative stress, inflammation or the cardiovascular system. There have been no adverse outcomes reported. Studies have demonstrated reduced markers of oxidative stress and inflammation and improved blood rheology. A larger number of experimental studies have been performed using astaxanthin. In particular, studies in a variety of animals using a model of myocardial ischemia and reperfusion have demonstrated protective effects from prior administration of astaxanthin both intravenously and orally. Future clinical studies and trials will help determine the efficacy of antioxidants such as astaxanthin on vascular structure, function, oxidative stress and inflammation in a variety of patients at risk of, or with, established cardiovascular disease. These may lead to large intervention trials assessing cardiovascular morbidity and mortality.

Advances and new frontiers in the pathophysiology of venous neointimal hyperplasia and dialysis access stenosis

Hemodialysis vascular access dysfunction is a major cause of morbidity and mortality in hemodialysis patients. The most common cause of this vascular access dysfunction is venous stenosis as a result of venous neointimal hyperplasia within the perianastomotic region (arteriovenous fistula) or at the graft-vein anastomosis (polytetrafluoroethylene, or PTFE, grafts). There have been few effective treatments to date for venous neointimal hyperplasia, in part, because of the poor understanding of the pathogenesis of venous neointimal hyperplasia. Therefore, this article will (1) describe the pathology of hemodialysis access stenosis in arteriovenous fistulas and grafts, (2) review and describe both current and novel concepts in the pathogenesis of neointimal hyperplasia formation, (3) discuss current and future novel therapies for treating venous neointimal hyperplasia, and (4) suggest future research areas in the field of hemodialysis vascular access dysfunction.

Low expression of thiosulfate sulfurtransferase (rhodanese) predicts mortality in hemodialysis patients

OBJECTIVES

To test the hypothesis that impaired expression of the thiosulfate sulfurtransferase rhodanese is associated with oxidative stress and may predict mortality in hemodialysis patients.

DESIGN AND METHODS

Sixty-two hemodialysis patients were investigated to determine protein and mRNA expression of rhodanese in monocytes. Whole cell reactive oxygen species and mitochondrial superoxide production were measured by fluorescence spectrophotometry.

RESULTS

Compared to healthy subjects, hemodialysis patients showed significantly lower rhodanese mRNA and protein expression and significantly increased reactive oxygen species. Lower rhodanese protein expression was significantly associated with higher mitochondrial superoxide production. The hazard ratio for mortality in hemodialysis patients with rhodanese mRNA below compared to patients above the median was 2.22. Survival was shorter with rhodanese mRNA below compared to patients above the median.

CONCLUSION

Impaired rhodanese expression is associated with increased whole cell reactive oxygen species as well as higher mitochondrial superoxide production and predicts mortality in hemodialysis patients.

Cardiovascular risk factors in patients with chronic kidney disease

Patients with chronic kidney disease have a higher burden of cardiovascular disease, which increases in a dose-dependent fashion with worsening kidney function. Traditional cardiovascular risk factors, including advanced age, diabetes mellitus, hypertension and dyslipidemia, have an important role in the progression of cardiovascular disease in patients who have a reduced glomerular filtration rate, especially in those with mild-to-moderate kidney disease. In patients with severe kidney disease, nontraditional or 'novel' risk factors, including inflammation, oxidative stress, vascular calcification, a prothrombotic milieu, and anemia, seem to confer additional risk. In this Review, we highlight factors that increase cardiovascular risk in patients with a reduced estimated glomerular filtration rate. In addition, we discuss therapeutic strategies for reducing cardiovascular risk in patients with kidney disease, whose unique atherosclerotic phenotype might require an approach that differs from traditional models developed in populations with normal kidney function. Therapeutic paradigms for patients with chronic kidney disease and cardiovascular risk factors must be evaluated in randomized trials, from which such patients have often been excluded.

Cardiovascular risk and management in chronic kidney disease

Chronic kidney disease (CKD) is associated with accelerated progression of cardiovascular disease, perhaps because patients with CKD have a high burden of traditional cardiovascular risk factors in addition to a range of nontraditional risk factors such as inflammation and abnormal metabolism of calcium and phosphate. Although the cardiovascular burden of CKD is well documented, potentially beneficial therapies are sometimes underused in patients with stage 3-4 CKD and are rarely studied in patients on dialysis. In this Review, we describe the epidemiology of cardiovascular disease in patients with stage 3-5 CKD (excluding kidney transplant recipients) and outline cardiovascular risk factors that are relevant in this population; we then discuss the implications of this knowledge for the optimal management of cardiovascular risk in this setting. Finally, we highlight opportunities for further research.

Malnutrition and wasting in renal disease

PURPOSE OF REVIEW

Malnutrition and accelerated catabolism frequently complicate chronic kidney disease and end-stage renal disease. This review provides an update on the recent advances in the understanding of the mechanisms underlying protein-energy wasting, both in experimental and human models, and on the currently available therapeutic approaches.

RECENT FINDINGS

Increased levels of circulating cytokines, metabolic acidosis, oxidative stress and insulin resistance all appear to be variably implicated in muscle protein breakdown during end-stage renal disease and dialysis. The individual role of each component in the pathogenesis of chronic kidney disease-related wasting is still unclear, but recent clinical data show a positive relationship between inflammation and muscle protein catabolism as a major contributing factor.

SUMMARY

The basis for appropriate therapeutic approaches to protein-energy wasting in chronic kidney disease and end-stage renal disease relies entirely on the understanding of its pathophysiology. Our knowledge of the pathogenesis of malnutrition and hypercatabolism in renal disease is still limited and mostly based on experimental data, but the currently available evidence suggests that multimodal preventive and therapeutic strategies should be entertained.

Treatment with N-acetylcysteine in stable renal transplantation

The primary cause of morbidity and mortality in renal transplantation is cardiovascular disease. Increased oxidative stress implies a greater degree of atherogenesis in these patients. N-acetylcysteine (NAC) which has a thiol group that is the source of l-cysteine and reduced glutathione, acts against atherosclerosis via a decrease in apoptosis, vasoconstriction, and endothelial dysfunction. Experimental models have examined the antioxidant effects of NAC during and after ischemia-reperfusion, but few studies have shown an effect in renal transplantation in human beings. In 8 months, we studied the effect of NAC treatment on oxidative stress, lipids, and renal function in 25 patients with stable renal function and no diabetes after transplantation. Data were collected on oxidative parameters: malondialdehyde, glutathione peroxidase, catalase, superoxide dismutase, glutathione reductase, lipid profile, and renal function (creatinine concentration, Cockroft-Gault formula, and Modified Diet in Renal Disease study). There were no significant differences in oxidative profile before and after treatment with NAC. The mean serum high-density lipoprotein cholesterol fraction increased after treatment and showed a significant positive correlation with glutathione peroxidase (r = 0.495). Serum creatinine concentration decreased, and Cockroft-Gault and Modified Diet in Renal Disease study estimates of renal function increased in the treatment period. In conclusion, NAC treatment in patients with stable renal function after transplantation increased high-density lipoprotein cholesterol and antioxidant molecules in relation to glutathione peroxidase, with a positive influence on renal function.

Hemodialysis versus peritoneal dialysis: a case control study of survival in patients with chronic kidney disease stage 5

It is still controversial whether the mode of dialysis or preexisting comorbidities may influence the prognosis of patients with chronic kidney disease stage 5. Therefore, we performed a prospective case control study to evaluate whether the mode of dialysis may influence outcome. We found 25 cases on peritoneal dialysis (PD) treatment and 75 age and sex-matched controls on hemodialysis (HD) treatment for more than 3 months. Analysis was by intention-to-treat. During the follow up of 58 months, 6 out of 25 patients (24%) died in the PD group, whereas in the HD group 26 out of 75 patients (35%) died (relative risk 0.69 [95% CI 0.32 to 1.49]; P = 0.46). Survival was not significantly different between the groups as indicated by Mantel-Cox log-rank test (hazard ratio 0.52 [95% CI 0.25 to 1.10]; P = 0.11). Multiple variable regression showed that age and diabetes mellitus, but not mode of dialysis, predicted death in patients with chronic kidney disease. It is concluded that age and comorbidities but not mode of dialysis are important to predict survival in patients with chronic kidney disease stage 5.

Review article: Biomarkers of clinical outcomes in advanced chronic kidney disease

Chronic kidney disease (CKD) is a complex condition, where the decrease in kidney function is accompanied by numerous metabolic changes affecting virtually all the organ systems of the human body. Many of the biomarkers characteristic of the individually affected organ systems have been associated with adverse outcomes including higher mortality in advanced CKD, whereas in persons without CKD these biomarkers may have no bearing on survival. It is believed that the high mortality seen in CKD is a result of several abnormalities conspiring to induce or aggravate a heightened degree of cardiovascular morbidity and predisposition to wasting syndrome. Not all the biomarkers may, however, be causally responsible for the adverse outcomes associated with them. We review various biomarkers of protein-energy wasting, inflammation, oxidative stress, potassium disarrays, acid-base disorders, bone and mineral disorders, glycemic status, and anemia. Although all of these biomarkers have shown associations with worsened outcomes in CKD, markers of protein-energy wasting, especially serum albumin, remain the strongest predictor of survival in CKD patients, especially those undergoing maintenance dialysis treatment. We also review the putative pathophysiologic mechanisms behind these associations, and present potential therapeutic interventions that could result in remedies to improve poor clinical outcomes in CKD, pending the results of current and future controlled trials.

Glutathione, vitamin E and oxidative stress in coronary artery disease: relevance of age and gender

BACKGROUND

Observational studies suggest that low levels of antioxidants are associated with high risk for coronary artery disease (CAD). We investigated whether the biomarkers of oxidative balance undergo the same modifications in all CAD patient groups, regardless of gender and age.

MATERIALS AND METHODS

One hundred sixty-eight CAD patients and 107 healthy controls were assayed for plasma levels of reduced glutathione (GSH), alpha- and gamma-tocopherol (alpha- and gamma-T) as endogenous antioxidants. A damage score (DS), representative of oxidative stress status, was calculated. ANCOVA models were used to test the association between antioxidants, DS and CAD and its modulation by age and gender.

RESULTS

The DS was higher in CAD than in controls. GSH levels, were lower in CAD patients (mean +/- SEM: 57.61 +/- 1.87 micromol 10 g(-1) haemoglobin vs. 68.55 +/- 2.23 in controls, P < 0.0006) in males and in older subjects. Levels of other antioxidants exhibited a complex pattern. Overall, no difference was found in alpha- and gamma-T contents between CAD and controls, but lower alpha-T values were observed in CAD females. A significant interaction between CAD status and gender was observed (P = 0.003).

CONCLUSIONS

Our study shows that the involvement of antioxidants in CAD is related to patients' characteristics. These findings may be relevant in planning antioxidant therapies.

Carbocysteine: clinical experience and new perspectives in the treatment of chronic inflammatory diseases

BACKGROUND

Carbocysteine is a muco-active drug with free radical scavenging and anti-inflammatory properties. It is actually approved for clinical use as adjunctive therapy of respiratory tract disorders characterized by excessive, viscous mucus, including chronic obstructive airways disease (COPD).

OBJECTIVE

The intriguing antioxidant and anti-inflammatory properties of carbocysteine, beyond its known mucolytic activity, are described to explain its therapeutic efficacy and suggest new clinical uses.

METHODS

After reviewing physiology and preclinical studies, human studies on the use of carbocysteine in chronic inflammatory diseases, i.e., COPD and cancer cachexia, are reviewed.

RESULTS/CONCLUSIONS

Carbocysteine has been recently recognized as an effective and safe treatment for the long-term management of COPD, able to reduce the incidence of exacerbations and improve patient quality of life. Moreover, carbocysteine was effective in counteracting some symptoms associated with cancer cachexia. Preclinical and clinical studies have demonstrated that the antioxidant and anti-inflammatory properties of carbocysteine are more important than mucolysis itself for its therapeutic efficacy. Therefore, carbocysteine may be able to reverse the oxidative stress associated with several chronic inflammatory diseases, such as cardiovascular diseases and neurodegenerative disorders. Controlled, randomized studies in humans are warranted.

The LDL modification hypothesis of atherogenesis: an update

The accumulated evidence that oxidative modification of LDL plays an important role in the pathogenesis of atherosclerosis in animal models is very strong. The negative results in recent clinical studies have caused many to conclude that LDL oxidation may not be relevant in the human disease. Yet many of the lines of evidence that support the hypothesis have been demonstrated to apply also in humans. In this review, we briefly summarize the lines of evidence on which the hypothesis rests, its strengths, and its weaknesses.

Nontraditional risk factors for cardiovascular disease in patients with chronic kidney disease

Patients with chronic kidney disease (CKD) have a reduced lifespan, and a substantial proportion of these individuals die from cardiovascular disease. Although a large percentage of patients with CKD have traditional cardiac risk factors such as diabetes, hypertension and abnormalities in cholesterol, interventions to address these factors--which have significantly decreased cardiovascular mortality in the general population--have not shown such benefit in the CKD population. In addition, the severity and extent of cardiovascular complications in patients with CKD is disproportionate to the number and severity of traditional risk factors. This realization has focused attention on nontraditional cardiac risk factors that are particularly relevant to patients with CKD, including decreased hemoglobin levels, microalbuminuria, increased inflammation and oxidative stress, and abnormalities in bone and mineral metabolism. However, large prospective trials in patients with advanced CKD or in those requiring chronic dialysis have not shown that normalization of these nontraditional risk factors improves survival. Moreover, the mechanisms by which these nontraditional risk factors contribute to cardiovascular disease are unknown. Therefore, although current treatment of patients with CKD includes management of traditional and nontraditional risk factors, the value of modifying some nontraditional risk factors remains unclear.

Iron, oxidative stress, and clinical outcomes

It is well known that iron is pro-oxidant. Chronic kidney disease (CKD) is a pro-oxidant state, and intravenous administration of iron is frequently used to correct anemia. On one hand, there is little doubt that iron causes oxidative stress. On the other, it is far from clear whether oxidative stress, so generated, leads to poor clinical outcomes. Iron has benefits that may be independent of the correction of anemia. Furthermore, concerns surround the use of high doses of erythropoietin in causing excess heart failure and death in patients with CKD. Thus, it would be prudent if iron were to continue to be used judiciously in patients who require erythropoietin. Iron, given orally, would be the preferred first-line agent in patients not on hemodialysis. In patients with sepsis, intravenous treatment with iron should be avoided, because, in animal experiments, intravenous administration of iron can compound the inflammatory response and increase mortality. Clinical trials are needed to ascertain the risk and benefits of the intravenous administration of iron in patients with CKD.

Randomized, blinded, placebo-controlled clinical trial of N-acetylcysteine in dogs with spinal cord trauma from acute intervertebral disc disease

STUDY DESIGN

The effect of N-acetylcysteine administration intravenously before hemilaminectomy surgery on neurologic outcome and 15F 2t isoprostane excretion in dogs was examined in a blinded, placebo-controlled trial.

OBJECTIVE

To determine the effect of N-acetylcysteine administration on urinary 15F 2t isoprostane excretion and neurologic outcome following hemilaminectomy for intervertebral disc disease.

SUMMARY OF BACKGROUND DATA

Oxidative stress is a mediator of secondary injury to the spinal cord following trauma. Acute intervertebral disc disease is associated with increased oxidative damage in dogs. N-acetylcysteine has preserved neurologic function following experimental spinal cord injury.

METHODS

Seventy dogs with naturally occurring acute intervertebral disc disease were administered either with saline placebo or N-acetylcysteine intravenously before hemilaminectomy surgery. Serial neurologic examinations were performed before and 1, 2, 7, 14, and 42 days following treatment. Urinary excretion of 15F 2t isoprostane excretion was determined before treatment and 1 hour after surgery.

RESULTS

Analysis of subjective data did not reveal any significant effect of N-acetylcysteine on neurologic outcome or rate of improvement of neurologic score in the 42 days following treatment. Urinary 15F 2t isoprostane excretion was not significantly different between treatment groups (P > 0.05).

CONCLUSION

N-acetylcysteine intravenously before hemilaminectomy has no effect on urinary 15F 2t isoprostane excretion or neurologic outcome. Treatment of dogs with the antioxidant N-acetylcysteine before hemilaminectomy, while not detrimental, does not affect neurologic outcome in the 42 days following surgery.

Cytokine dysregulation in chronic kidney disease: how can we treat it?

As the kidney is the major site for elimination of many cytokines, the delicate equilibrium of pro-inflammatory cytokines and their inhibitors is clearly dysregulated in chronic kidney disease (CKD) patients. The consequences of the altered immune response in uremia lead to a state of persistent inflammation which is highly prevalent among CKD patients and is linked to complications such as the development of protein-energy wasting and atherosclerotic vascular disease. The present review aims at reviewing this complex orchestration of uremic cytokines beyond the well-studied interleukin-6 and tumor necrosis factor-alpha. Finally, we update our current understanding on anti-inflammatory treatment strategies in CKD patients, including nutritional and lifestyle measurements, pharmacological intervention and specific anticytokine strategies targeting the dialytic procedure.

Cognitive function in chronic kidney disease

Chronic kidney disease (CKD) is a growing public health problem. The incidence of kidney failure is rising in all age groups but particularly in older adults. Individuals in all stages of CKD are at higher risk for development of cognitive impairment and this may be a major determinant in their quality of life. Furthermore, cognitive impairment is associated with an increased risk of death in dialysis patients. Cerebrovascular disease is a strong risk factor for development of cognitive impairment and vascular disease is a more likely cause of cognitive impairment than Alzheimer's disease in patients with CKD. Both traditional and nontraditional vascular risk factors are more common in CKD and dialysis patients may also be at risk for cognitive impairment via nonvascular risk factors and the hemodialysis procedure itself. Unfortunately, because risk factors for cognitive impairment in CKD have not been thoroughly ascertained, evaluation of potential treatments has been limited. Given the high prevalence of cognitive impairment in all stages of CKD, additional studies are needed to evaluate potential risk factors and treatments in this vulnerable population.

Novel targets and new potential: developments in the treatment of inflammation in chronic kidney disease

BACKGROUND

Patients with chronic kidney disease (CKD) of all stages experience extremely high mortality, with cardiovascular causes accounting for about half of all their deaths. Traditional risk factors such as hypertension, hypercholesterolemia and diabetes mellitus cannot explain the excessively high cardiovascular mortality in CKD. Chronic inflammation is one of the novel risk factors that appear to contribute to the increased mortality seen in patients with CKD. Therapeutic interventions targeting chronic inflammation in CKD may lead to improved outcomes.

OBJECTIVES

To describe the role of inflammation in CKD and to review anti-inflammatory pharmacologic therapies that could have a role in its therapy.

METHODS

A review of the literature was carried out and expert opinion expressed.

RESULTS/CONCLUSION

Inflammation is a common and significant problem in CKD. There are currently no approved pharmacologic anti-inflammatory therapies in CKD but several agents are being studied in early clinical trials, while others could become viable alternatives in the future.

Aberrant insulin receptor signaling and amino acid homeostasis as a major cause of oxidative stress in aging

The mechanisms leading to the increase in free radical-derived oxidative stress in "normal aging" remains obscure. Here we present our perspective on studies from different fields that reveal a previously unnoticed vicious cycle of oxidative stress. The plasma cysteine concentrations during starvation in the night and early morning hours (the postabsorptive state) decreases with age. This decrease is associated with a decrease in tissue concentrations of the cysteine derivative and quantitatively important antioxidant glutathione. The decrease in cysteine reflects changes in the autophagic protein catabolism that normally ensures free amino acid homeostasis during starvation. Autophagy is negatively regulated by the insulin receptor signaling cascade that is enhanced by oxidative stress in the absence of insulin. This synopsis of seemingly unrelated processes reveals a novel mechanism of progressive oxidative stress in which decreasing antioxidant concentrations and increasing basal (postabsorptive) insulin receptor signaling activity compromise not only the autophagic protein catabolism but also the activity of FOXO transcription factors (i.e., two functions that were found to have an impact on lifespan in several animal models of aging). In addition, the aging-related decrease in glutathione levels is likely to facilitate certain "secondary" disease-related mechanisms of oxidative stress. Studies on cysteine supplementation show therapeutic promise.

Emerging biomarkers for evaluating cardiovascular risk in the chronic kidney disease patient: how do new pieces fit into the uremic puzzle?

Premature cardiovascular disease (CVD), including stroke, peripheral vascular disease, sudden death, coronary artery disease, and congestive heart failure, is a notorious problem in patients with chronic kidney disease (CKD). Because the presence of CVD is independently associated with kidney function decline, it appears that the relationship between CKD and CVD is reciprocal or bidirectional, and that it is this association that leads to the vicious circle contributing to premature death. As randomized, placebo-controlled trials have so far been disappointing and unable to show a survival benefit of various treatment strategies, such a lipid-lowering, increased dialysis dose and normalization of hemoglobin, the risk factor profile seems to be different in CKD compared with the general population. Indeed, seemingly paradoxical associations between traditional risk factors and cardiovascular outcome in patients with advanced CKD have complicated our efforts to identify the real cardiovascular culprits. This review focuses on the many new pieces that need to be fit into the complicated puzzle of uremic vascular disease, including persistent inflammation, endothelial dysfunction, oxidative stress, and vascular ossification. Each of these is not only highly prevalent in CKD but also more strongly linked to CVD in these patients than in the general population. However, a causal relationship between these new markers and CVD in CKD patients remains to be established. Finally, two novel disciplines, proteomics and epigenetics, will be discussed, because these tools may be helpful in the understanding of the discussed vascular risk factors.

Applying Translational Research in Understanding Complications and Defining Targets for Intervention: Inflammation in PD as a Model

The bench-to-bedside approach to translational research is becoming increasingly important to efficiently advance understanding of the mechanisms underlying disease and to improve the quality of patient care. Although this investigation model has been practiced since the early days of the therapy, robust research platforms built to practice translational research have only recently been structured in the field of peritoneal dialysis. Experience with a translational research environment that generated most of the information cited in this overview is the core of this manuscript. The central investigation theme described is how to approach the cardiovascular complications of peritoneal dialysis. The research question was, could the continuous activation of inflammatory pathways be central in this process and represent a relevant target for interventions?

Cardiovascular disease in dialysis patients: do some antihypertensive drugs have specific antioxidant effects or is it just blood pressure reduction? Does antioxidant treatment reduce the risk for cardiovascular disease?

PURPOSE OF REVIEW

Patients with end-stage renal disease have an extremely high cardiovascular disease mortality. Oxidative stress is one of the 'nontraditional' risk factors for cardiovascular disease mortality in dialysis patients. This review discusses antioxidant activity of the commonly prescribed antihypertensive agents and the effects of antioxidant interventions on cardiovascular disease mortality in patients with end-stage renal disease.

RECENT FINDINGS

Several lines of evidence confirm antioxidant activity of the renin-angiotensin-aldosterone antagonists, some of the calcium channel blockers, carvedilol, and hydralazine. This appears to be independent of their antihypertensive activity. Clinical evidence of their superiority in improving cardiovascular disease endpoints in end-stage renal disease, however, is lacking. There are no randomized trials that have examined the effect of correcting oxidative stress on clinical endpoints. One randomized study in patients on hemodialysis reported a reduction in oxidative stress and the plasma methylarginines with valsartan and amlodipine but no clinical endpoints were examined.

SUMMARY

The effects of the antihypertensive agents with antioxidant activity on cardiovascular disease mortality in end-stage renal disease have not been examined in randomized clinical trials. These agents may offer specific clinical advantage in addition to lowering the blood pressure, but this remains to be proven. Two studies show a reduction in cardiovascular disease events with vitamin E and N-acetylcysteine in patients on hemodialysis without an effect on overall mortality.

Kinetic studies of atherogenic lipoproteins in hemodialysis patients: do they tell us more about their pathology?

Patients with chronic kidney disease have one of the highest risks for atherosclerotic complications. Several large epidemiological studies described an opposite association of total and low density lipoprotein (LDL) cholesterol with cardiovascular complications and total mortality compared to the general population, a circumstance often called "reverse epidemiology." Many factors might contribute to this reversal such as interaction with malnutrition/inflammation, pronounced fluctuations of atherogenic lipoproteins during the course of renal disease, heterogeneity of lipoprotein particles with preponderance of remnant particles, and chemical modification of lipoproteins caused by the uremic environment. A vicious cycle has been suggested in uremia in which the decreased catabolism of atherogenic lipoproteins such as LDL, IDL and Lp(a) leads to their increased plasma residence time and further modification of these lipoproteins by oxidation, carbamylation, and glycation. Using stable isotope techniques, it has been shown recently that the plasma residence time of these particles is more than twice as long in hemodialysis patients as in nonuremic subjects. This reduced catabolism, however, is masked by the decreased production of LDL, resulting in near-normal plasma levels of LDL. The production rate of Lp(a) in hemodialysis patients is similar to that in controls which together with the doubled residence time results in elevated Lp(a) levels. An increased clearance of these altered lipoproteins via the scavenger receptors of macrophages leads to the transformation of macrophages into foam cells in the vascular wall and might contribute to the pronounced risk for cardiovascular complications of these patients. These observations suggest that the real danger of these particles is not reflected by the measured concentrations but by their metabolic qualities.

Homocysteinemia correlates with plasma thiol redox status in patients with end-stage renal disease

BACKGROUND/AIMS

In end-stage renal disease (ESRD), hyperhomocysteinemia is a common finding associated with increased cardiovascular risk. However, the pathogenic role of homocysteine is still unclear. In vitro studies show that thiol redox status affects endothelial cell functions. We therefore investigated the possible association between homocysteinemia and plasma thiol redox status in ESRD patients.

METHODS

Total plasma homocysteine (Hcy), cysteine (Cys) and free thiols (SH) were measured both before and after a dialytic session in 54 ESRD patients receiving (n = 15) or not receiving (n = 39) folate supplementation, and 17 control subjects.

RESULTS

High predialysis levels of both Hcy and Cys were found to be negatively correlated with low SH levels both in supplemented (r = -0.680, p < 0.01 and r = -0.624, p < 0.02, respectively) and unsupplemented (r = -0.698, p < 0.001 and r = -0.445, p < 0.01, respectively) patients. Following dialysis, SH values returned to normal and the above correlations were no longer appreciable.

CONCLUSION

A strong, folate therapy-insensitive association between homocysteinemia and plasma free thiol levels was found in ESRD patients. These results support a role for oxidative stress in ESRD-related hyperhomocysteinemia and suggest the plasma thiol redox status alteration as a possible pathogenic mechanism underlying the cardiovascular toxicity of hyperhomocysteinemia in these patients.

Management of ischemic heart disease in patients with chronic kidney disease

Patients with chronic kidney disease (CKD) and ischemic heart disease (IHD) have strikingly high mortality rates. In the general population, there has been a reduction in the mortality and morbidity rates for IHD through the implementation of effective risk-factor-reduction programs and better interventions for patients with established IHD. No such trend has been observed in patients with end-stage kidney disease. This review article addresses the following topics: (i) epidemiology, pathogenesis, clinical CKD patients with IHD; (ii) diagnostic modalities for IHD and their limitation in CKD patients; (iii) medical treatment options and revascularization strategies for these high-risk patients; and (iv) optimal cardiovascular risk management. Generally, in CKD patients with IHD an aggressive approach to IHD is warranted, a low threshold for diagnostic testing should be employed, and awaiting a clinical trial targeting these patients they should be considered for all proven strategies to improve outcomes.

Gamma-tocopherol and docosahexaenoic acid decrease inflammation in dialysis patients

OBJECTIVE

Increased cardiovascular risk in hemodialysis patients may be related to augmented oxidative stress and inflammation, for which no proven beneficial therapies are available.

STUDY DESIGN

We examined the effects of gamma tocopherol and docosahexaenoic acid (DHA) administration on inflammation and oxidative stress markers in hemodialysis patients in a randomized, double-blinded, placebo-controlled, clinical trial. Active treatment consisted of capsules containing gamma tocopherol (308 mg) and DHA (800 mg).

SETTING

Outpatient dialysis center.

PATIENTS

Seventy maintenance hemodialysis patients.

MAIN OUTCOME MEASURES

Plasma concentrations of interleukin-6 (IL-6) and protein carbonyl content were determined by enzyme-linked immunosorbant assay. C-reactive protein was measured by nephelometry. The F(2) isoprostanes were measured by gas chromatography-mass spectrometry. Erythrocyte DHA content was measured by gas chromatography.

RESULTS

Sixty-three patients were enrolled, and 57 completed the study. No serious adverse events were attributed to either active treatment or placebo. In the treatment group, but not in the placebo group, there were significant decreases in IL-6 (21.4 +/- 3.5 to 16.8 +/- 3.7 pg/mL), white blood cell (WBC) count (7.4 +/- 0.3 to 6.9 +/- 0.4 10(3)/microL), and neutrophil fraction of WBCs (4.8 +/- 0.3 to 4.4 +/- 0.3 10(3)/microL), at P < .05 for all. There were no significant changes in plasma concentrations of CRP, F(2) isoprostanes, or carbonyls in either group.

CONCLUSION

Thus, gamma tocopherol and DHA are well-tolerated and reduce selected biomarkers of inflammation in hemodialysis patients. Larger randomized, clinical trials will be required to determine if gamma tocopherol and DHA can reduce cardiovascular complications in hemodialysis patients.

Novel pharmacological approaches to the treatment of renal ischemia-reperfusion injury: a comprehensive review

Renal ischemia-reperfusion (I-R) contributes to the development of ischemic acute renal failure (ARF). Multi-factorial processes are involved in the development and progression of renal I-R injury with the generation of reactive oxygen species, nitric oxide and peroxynitrite, and the decline of antioxidant protection playing major roles, leading to dysfunction, injury, and death of the cells of the kidney. Renal inflammation, involving cytokine/adhesion molecule cascades with recruitment, activation, and diapedesis of circulating leukocytes is also implicated. Clinically, renal I-R occurs in a variety of medical and surgical settings and is responsible for the development of acute tubular necrosis (a characteristic feature of ischemic ARF), e.g., in renal transplantation where I-R of the kidney directly influences graft and patient survival. The cellular mechanisms involved in the development of renal I-R injury have been targeted by several pharmacological interventions. However, although showing promise in experimental models of renal I-R injury and ischemic ARF, they have not proved successful in the clinical setting (e.g., atrial natriuretic peptide, low-dose dopamine). This review highlights recent pharmacological developments, which have shown particular promise against experimental renal I-R injury and ischemic ARF, including novel antioxidants and antioxidant enzyme mimetics, nitric oxide and nitric oxide synthase inhibitors, erythropoietin, peroxisome-proliferator-activated receptor agonists, inhibitors of poly(ADP-ribose) polymerase, carbon monoxide-releasing molecules, statins, and adenosine. Novel approaches such as recent research involving combination therapies and the potential of non-pharmacological strategies are also considered.

Angiotensin II-induced reactive oxygen species and the kidney

Angiotensin II (AngII) is an important mediator in renal injury. Accumulating evidence suggests that AngII stimulates intracellular formation of reactive oxygen species (ROS) such as the superoxide anion and hydrogen peroxide. AngII activates several subunits of the membrane-bound multicomponent NAD(P)H oxidase and also increases ROS formation in the mitochondria. Some of these effects may be induced by aldosterone and not directly by AngII. The superoxide anion and hydrogen peroxide influence other downstream signaling pathways, such as transcription factors, tyrosine kinases/phosphatases, ion channels, and mitogen-activated protein kinases. Through these signaling pathways, ROS have distinct functional effects on renal cells. They are transducers of cell growth, apoptosis, and cell migration and affect expression of inflammatory and extracellular matrix genes. For example, AngII-mediated expression of p27(Kip1), a cell-cycle regulatory protein, and induction of tubular hypertrophy depend on the generation of ROS. The effects of ROS generated within different renal cells ultimately depend on the locally generated concentrations and the balance of pro- and antioxidant pathways. Although the concept that AngII mediates oxidative stress in the kidney has been validated in experimental models, the exact role is still incompletely understood in human renal diseases.

Effect of N-Acetylcysteine on Endothelial Dysfunction in Dialysis Patients

BACKGROUND/AIMS

Patients with K/DOQI stage 5 chronic kidney disease (CKD) have higher incidence of cardiovascular events due to the oxidative stress and endothelial dysfunction (ED). The aim of this study is to evaluate the effects of N-acetylcysteine (NAC), which might prevent cardiovascular events by improving oxidative stress on endothelial cells in patients with CKD.

METHODS

Thirty uremic patients (age 40 +/- 12 years, 6 males) on hemodialysis (HD) were evaluated for ED by using high-resolution Doppler ultrasound of brachial artery before and after 6 weeks of oral NAC (2 x 600 mg) medication. Also, 13 healthy controls (35 +/- 9 years, 5 males) were included in the study. Reactive hyperemia following 5 min forearm ischemia was accepted as endothelium-dependent vasodilatation (flow-mediated dilatation; FMD) and compared to endothelium-independent vasodilatation in response to sublingual glyceril trinitrate (GTN).

RESULTS

Patients on HD had lower DeltaFMD (0.28 +/- 0.17 vs. 0.41 +/- 0.11, p < 0.05) and FMD% (7.5 +/- 5.05 vs. 11.33 +/- 2.95, p < 0.05) than the controls. Baseline DeltaGTN and GTN% were similar in two groups. NAC treatment significantly increased the DeltaFMD (0.41 +/- 0.11, p < 0.001 vs. baseline) and FMD% (10.59 +/- 3.22, p < 0.01 vs. baseline) of patients on HD, while it had no effect on DeltaGTN and GTN%.

CONCLUSION

These results suggest that NAC treatment could improve the ED by preventing the reduction of FMD in patients on HD.

The uremic solute indoxyl sulfate induces oxidative stress in endothelial cells

BACKGROUND

Endothelial dysfunction and oxidative stress are matters of concern in patients with chronic renal failure (CRF). Uremic solutes retained in these patients could be involved in these processes. Notably, the protein-bound uremic solute indoxyl sulfate induces endothelial dysfunction in vitro, and has shown pro-oxidant effects.

OBJECTIVE

To demonstrate that indoxyl sulfate is a potential mediator of oxidative stress in endothelial cells in vitro.

METHODS

Indoxyl sulfate-induced oxidative stress in human umbilical vein endothelial cells (HUVEC) was studied by measuring reactive oxygen specie (ROS) production by cytofluorimetry, by analyzing the involvement of the pro-oxidative enzymes NAD(P)H oxidase, xanthine oxidase, and NO synthase, and by measuring the levels of the non-enzymatic antioxidant glutathione.

RESULTS

We showed that indoxyl sulfate induced a significant production of ROS in HUVEC, with or without human serum albumin. We then investigated the role of pro-oxidative enzymes and measured the levels of the antioxidant glutathione. The NAD(P)H oxidase inhibitors, DPI, and apocynin, inhibited ROS production, whereas inhibitors of xanthine oxidase, NO synthase, and mitochondrial ROS had no effect. Interestingly, indoxyl sulfate strongly decreased the levels of glutathione, one of the most active antioxidant systems of the cell. In addition, the ROS production mediated by indoxyl sulfate was inhibited by the antioxidants vitamin C, vitamin E, and NAC.

CONCLUSION

The uremic solute indoxyl sulfate enhances ROS production, increases NAD(P)H oxidase activity, and decreases glutathione levels in endothelial cells. Thus, indoxyl sulfate induces oxidative stress by modifying the balance between pro- and antioxidant mechanisms in endothelial cells.

Gentamicin-induced ototoxicity in hemodialysis patients is ameliorated by N-acetylcysteine

Aminoglycoside (AG) antibiotics are associated with several side effects, including a reversible nephrotoxicity and a permanent ototoxicity. Oxidative stress is thought to contribute to the pathophysiology of both conditions. We studied the possible protective effect of the antioxidant N-acetylcysteine (NAC) in gentamicin-induced hearing loss in hemodialysis patients. This study includes 53 hemodialysis patients scheduled to receive gentamicin for dialysis catheter-related bacteremia that were randomized to receive the antibiotic with or without NAC. Hearing function was assessed by the standard technique of pure-tone audiograms over a range of frequencies. Audiometric evaluations were performed at baseline, 1 week and at 6 weeks after the completion of gentamicin therapy. A total of 40 patients completed the study protocol with a mean duration of therapy of almost 15 days. At both 1 and 6 weeks after the completion of antibiotic therapy, there were significantly more patients exhibiting ototoxicity in the control group compared with the group receiving NAC. Additionally, significantly more patients in the control group had bilateral ototoxicity. The greatest otoprotective effect of NAC was noticed in the high audiometric tone frequencies. Taken together, our study suggests that NAC treatment may ameliorate gentamicin-induced ototoxicity in hemodialysis patients.

Intravenous N-acetylcysteine during haemodialysis reduces the plasma concentration of homocysteine in patients with end-stage renal disease

BACKGROUND

Hyperhomocysteinaemia is an independent cardiovascular risk factor in patients with renal disease. The current study aimed to determine the effect of intravenous N-acetylcysteine on plasma homocysteine levels when administered during haemodialysis in patients with end-stage renal failure.

PATIENTS AND METHODS

Sixty patients with end-stage renal failure were randomised to receive a 4-hour intravenous infusion of N-acetylcysteine or placebo during a 4-hour haemodialysis session. Plasma homocysteine levels were measured before and after haemodialysis. Haemodynamic parameters, including pulse pressure, were also measured.

RESULTS

After haemodialysis in the placebo treatment group, plasma homocysteine was reduced by 23.7% from the pre-dialysis level, whereas patients treated with N-acetylcysteine exhibited an 88.3% decrease (p < 0.001). Reduction of plasma homocysteine concentration was significantly correlated with a reduction of pulse pressure (p = 0.001). A 10% decrease in plasma homocysteine concentration was associated with a 1.45mm Hg decrease in pulse pressure.

CONCLUSIONS

Intravenous administration of N-acetylcysteine during haemodialysis normalises plasma homocysteine concentration, and this is associated with improved pulse pressure in patients with end-stage renal failure. Intravenous administration of N-acetylcysteine during haemodialysis may be a promising approach to help reduce cardiovascular risk in this vulnerable group of patients.

Kidney Disease and Cardiovascular Risk

Kidney failure and chronic kidney disease (CKD) are associated with accelerated cardiovascular disease, apparently because of a high burden of traditional vascular risk factors and possibly nontraditional risk factors such as inflammation, chronic volume overload, and abnormal calcium-phosphate metabolism. Although the burden of cardiovascular disease in CKD patients is well documented, potentially beneficial therapies appear to be underused in mild to moderate CKD and are relatively understudied in those with kidney failure. This review describes the epidemiology and pathophysiology of cardiovascular disease in CKD. We also discuss the clinical and public health implications of current knowledge and outline opportunities for further research.

Modification of cardiovascular risk in hemodialysis patients: An evidence-based review

Cardiovascular disease accounts for 40% to 50% of deaths in dialysis populations. Overall, the risk of cardiac mortality is 10-fold to 20-fold greater in dialysis patients than in age and sex-matched controls without chronic kidney disease. The aim of this paper is to review critically the evidence that cardiac outcomes in dialysis patients are modified by cardiovascular risk factor interventions. There is limited, but as yet inconclusive controlled trial evidence that cardiovascular outcomes in dialysis populations may be improved by antioxidants (vitamin E or acetylcysteine), ensuring that hemoglobin levels do not exceed 120 g/L (especially in the setting of known cardiovascular disease), prescribing carvedilol in the setting of dilated cardiomyopathy, and by using cinacalcet in uncontrolled secondary hyperparathyroidism. Similarly, there are a number of negative controlled trials, which have demonstrated that statins, high-dose folic acid, angiotensin-converting enzyme inhibitors, multiple risk factor intervention via multidisciplinary clinics, and high-dose or high-flux dialysis are ineffective in preventing cardiovascular disease. Although none of these studies could be considered conclusive, the negative trials to date should raise significant concerns about the heavy reliance of current clinical practice guidelines on extrapolation of findings from cardiovascular intervention trials in the general population. It may be that cardiovascular disease in dialysis populations is less amenable to intervention, either because of the advanced stage of chronic kidney disease or because the pathogenesis of cardiovascular disease in dialysis patients is different from that in the general population. Large, well-conducted, multicenter randomized-controlled trials in this area are urgently required.

Effects of amlodipine and valsartan on oxidative stress and plasma methylarginines in end-stage renal disease patients on hemodialysis

Patients with end-stage renal disease (ESRD) receiving hemodialysis (HD) treatment have a markedly shortened life expectancy in large part owing to cardiovascular disease (CVD), not explained by established risk factors. We tested the hypothesis that therapy with valsartan, an angiotensin receptor blocker and amlodipine, an antioxidant calcium channel blocker will reduce oxidative stress and the plasma levels of asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase. We confirmed that compared with age- and gender-matched healthy controls, ESRD patients have excessive oxidative stress and arginine methylation as indexed by elevated plasma levels of oxidation products of lipids (13-hydroxyoctadecadienoic acid (13-HODE)), thiols (oxidized:reduced glutathione, oxidized glutathione (GSSG):GSH), proteins, and nucleic acids, and the methylation products ADMA and symmetric dimethylarginine (SDMA). We undertook a double blind, crossover study of equi-antihypertensive treatment with amlodipine and valsartan for 6 weeks each to test our hypothesis. Both treatments significantly reduced GSSG:GSH, 8-hydroxy 2-deoxyguanosine, ADMA, and SDMA levels and amlodipine reduced 13-HODE. We conclude that hypertensive patients with ESRD receiving HD have evidence of extensive oxidation of lipids, thiols, proteins, and nucleic acids and methylation of arginine that could contribute to CVD. Many of these changes can be reduced by short-term treatment with amlodipine and valsartan.

Spontaneous leukocyte activation and oxygen-free radical generation in end-stage renal disease

Oxidative stress and inflammation are common features and major mediators of atherosclerosis in end-stage renal disease (ESRD). Available evidence for oxidative stress in ESRD is indirect and based on accumulation of byproducts of interactions of reactive oxygen species (ROS) with various molecules. Inflammation is a major cause of oxidative stress. To explore the direct link between oxidative stress and inflammation in ESRD, we studied leukocyte integrin expression and ROS production in 18 ESRD patients and 18 controls. ESRD patients showed elevated plasma malondialdehyde (MDA) and increased superoxide and hydrogen peroxide (H(2)O(2)) production by granulocytes and monocytes before dialysis. Hemodialysis resulted in a further rise in plasma MDA and H(2)O(2) production by granulocytes and monocytes. Surface expression of Mac-1 (CD11b and CD18) on granulocytes and monocytes was significantly increased (denoting cell activation) in ESRD patients. Granularity of granulocytes was significantly reduced before dialysis and declined further after dialysis. The magnitude of ROS production by granulocytes and monocytes was directly related with CD11b expression as well as plasma ferritin and parathyroid hormone levels and was inversely related to protein catabolic rate. Thus, this study provides direct evidence of spontaneous leukocyte activation and increased ROS generation (hence the link between oxidative stress and inflammation) in ESRD patients.

Cardiovascular Biomarkers in CKD: Pathophysiology and Implications for Clinical Management of Cardiac Disease

Cardiovascular disease (CVD) is a major cause of morbidity and mortality in patients with all forms of chronic kidney disease (CKD). The underlying pathological state is caused by a complex interplay of traditional and nontraditional risk factors that results in atherosclerosis, arteriosclerosis, and altered cardiac morphological characteristics. This multifactorial disease introduces new challenges in predicting and treating patients with CVD sufficiently early in the course of CKD to positively alter patient outcome. Asymptomatic individuals with progressive CVD are a group of patients that deserve focused attention because early detection and intervention may provide the best opportunity for improved outcome. However, identifying CVD in asymptomatic patients with CKD or end-stage renal disease remains a significant hurdle in the management of these patients. Recently, a number of cardiovascular biomarkers were identified as predictors of patient outcome in individuals with CVD and, with additional research, may be used to guide the early diagnosis of and therapy for CVD in patients with CKD. This review examines the pathophysiological characteristics and potential clinical role of these novel cardiovascular biomarkers in risk stratification, risk monitoring, and selection of preventive therapies for patients with CKD.

Kidney disease as an independent risk factor for cardiovascular events

Although the high risk for cardiovascular events in patients with end-stage renal disease (ESRD) is well known, recent data provide compelling evidence that even mild to moderate kidney disease is an important and independent risk factor for cardiac events. This increased risk does not seem to be explained by traditional risk factors as defined by the Framingham cohort. The examination of nontraditional risk factors has resulted in the identification of, among others, oxidant stress, hyperhomocystinemia, carbamylation, nitric oxide synthase inhibitors, and abnormal lipoproteins as potential pathways to explain the accelerated atherosclerosis in patients with kidney disease. Well-designed clinical trials should lead to the clarification of the relative importance of these factors in the pathogenesis of atherosclerotic disease.

Serum myeloperoxidase and mortality in maintenance hemodialysis patients

BACKGROUND

During inflammation, myeloperoxidase (MPO) is released, for which its measurement in systemic circulation may be used as an index of leukocyte activation and oxidant stress. MPO levels correlate with angiographic evidence of coronary atherosclerosis and cardiovascular events in subjects with chest pain within the general population. We hypothesized that serum MPO levels are associated with adverse clinical outcomes in maintenance hemodialysis (MHD) patients.

METHODS

MPO levels were determined in serum samples from 356 MHD patients at the start of a 3-year cohort.

RESULTS

Patients (46% women, 28% blacks, 54% with diabetes) were 54.6 +/- 14.6 (SD) years old and had undergone MHD for a median period of 26 months. Measured serum MPO level was 2,005 +/- 1,877 pmol/L (median, 1,444 pmol/L; interquartile range, 861 to 2,490 pmol/L). MHD patients with greater total body fat had greater MPO levels. MPO level had statistically significant (P < 0.01) and positive correlations with values for serum C-reactive protein (CRP; r = +0.15), interleukin 6 (IL-6; r = +0.23), tumor necrosis factor alpha (TNF-alpha; r = +0.21), and white blood cell count (r = +0.21). A death hazard ratio for each 1,000-pmol/L increase in serum MPO level was 1.14 (95% confidence interval [CI], 1.03 to 1.26; P = 0.01) after controlling for age, race (black), diabetes mellitus, dialysis vintage, Charlson comorbidity score, history of previous cardiovascular disease, blood hemoglobin level, and serum concentrations of albumin, CRP, IL-6, and TNF-alpha. After dividing MPO values into 3 equal groups (tertiles), the death hazard ratio of the highest tertile (versus the middle tertile) was 1.82 (95% CI, 1.07 to 3.10; P = 0.03).

CONCLUSION

Serum MPO levels correlate with levels of markers of inflammation and prospective mortality risk in MHD patients.

Effects of acetylcysteine and ischaemic preconditioning on muscular function and postoperative pain after orthopaedic surgery using a pneumatic tourniquet

BACKGROUND AND OBJECTIVE

The use of a pneumatic tourniquet can induce muscular and neurological complications in the operated limb. The genesis of these injuries could involve an ischaemia/reperfusion phenomenon and a compression under the cuff. We evaluated effects of an antioxidant, acetylcysteine and ischaemic preconditioning on the rhabdomyolysis and postoperative pain following a knee ligamentoplasty using a pneumatic tourniquet.

METHODS

We included 31 patients scheduled for a knee ligamentoplasty randomly assigned in three groups (control, acetylcysteine 1200 mg the day before and 600 mg at the operative day, ischaemic preconditioning).

RESULTS

There was a moderate rise in myoglobin and creatinine phosphokinase with no significant difference between the three groups. The muscular functional parameters were similar in all the groups. However, the morphine consumption within the first 48 h was smaller in the treatment groups (0.22 +/- 0.31 mg kg-1 and 0.22 +/- 0.23 mg kg-1 in the preconditioning and antioxidant groups, respectively) than in the control group (0.47 +/- 0.33 mg kg-1, P <0.05).

CONCLUSIONS

Acetylcysteine and ischaemic preconditioning do not decrease the extent of rhabdomyolysis related to the use of a pneumatic tourniquet and do not improve the postoperative muscle recovery. On the other hand, they allow a significant reduction in the postoperative morphine consumption.

N-3 Fatty Acids as Secondary Prevention against Cardiovascular Events in Patients Who Undergo Chronic Hemodialysis: A Randomized, Placebo-Controlled Intervention Trial

Patients who are treated with chronic hemodialysis (HD) experience premature cardiovascular disease and an increased mortality. N-3 polyunsaturated fatty acids (PUFA) may be effective in the secondary prevention of cardiovascular disease, but the effects of n-3 PUFA has not previously been examined in HD patients. It was hypothesized that secondary prevention with n-3 PUFA would reduce the number of cardiovascular events and death in patients who are treated with chronic HD. A randomized, double-blind, placebo-controlled intervention trial compared the effect of n-3 PUFA and a control treatment as secondary prevention of cardiovascular events in HD patients. The primary outcome was a composite of total cardiovascular events and death. A total of 206 patients were randomly assigned to treatment with n-3 PUFA or control treatment and followed for 2 yr or until reaching a predefined end point. During the trial, 121 (59%) of 206 patients reached a primary end point. N-3 PUFA had no significant effect on the primary composite end point of cardiovascular events and death (62 versus 59; NS). In the n-3 PUFA group, a significant reduction was seen in the number of myocardial infarctions (four versus 13; P = 0.036). This trial was limited by a relatively small number of patients and a large number of withdrawals. However, it is concluded that treatment with n-3 PUFA did not reduce the total number of cardiovascular events and death in this high-risk population. N-3 PUFA significantly reduced the number of myocardial infarctions as a secondary outcome, a finding that might be of clinical interest.

Recent advances in understanding the malnutrition-inflammation-cachexia syndrome in chronic kidney disease patients: What is next?

Several recent clinical trials using single modalities to correct the conventional cardiovascular risk factors in patients with chronic kidney disease (CKD) or to improve dialysis dose and techniques in maintenance dialysis patients have failed despite the high rate of cardiovascular mortality in these individuals. Protein-energy malnutrition and inflammation, two relatively common and concurrent conditions in CKD patients, have been implicated as the main cause of poor short-term survival in this population. The "malnutrition-inflammation-cachexia syndrome" (MICS) appears to be the main cause of worsening atherosclerotic cardiovascular disease in the CKD population. The MICS is associated with low serum cholesterol and homocysteine levels and leads to "cachexia in slow motion." Hence a reverse epidemiology of cardiovascular risk factors is observed in dialysis patients with a paradoxical association of obesity, hypercholesterolemia, and hyperhomocysteinemia with better survival. Correction of MICS can potentially ameliorate the cardiovascular epidemic in CKD patients. Because MICS is multifactorial, its correction will require an integral approach rather than a single intervention. The ongoing obsession with conventional cardiovascular risk factors largely reflecting overnutrition in a population that suffers from the short-term consequences of undernutrition and excessive inflammation may well be fruitless. Clinical trials focusing on the causes and consequences of MICS and its modulation using nutritional interventions may be the key to improving survival in these individuals.