Melatonin prevents oxidative stress resulting from iron and erythropoietin administration

Hemodialysis-induced chronodisruption and chronotype distribution in patients with chronic kidney disease

Changes in circadian rhythms have been observed in patients with chronic kidney disease (CKD), and evidence suggests that these changes can have a negative impact on health. This study aimed to investigate the existence of hemodialysis-induced chronodisruption, the chronotype distribution, and their association with sleep quality and quality of life (QoL). This was a cross-sectional study that enrolled 165 patients (mean age: 51.1 ± 12.5 y, 60.6% male) undergoing hemodialysis from three local units. The following instruments were used: the Morning-Eveningness Questionnaire (MEQ); a modified version of the Munich Chronotype Questionnaire (MCQT) to estimate hemodialysis-induced chronodisruption (HIC); the Kidney Disease QoL Short Form (KDQOL-SF); the Epworth Sleepiness Scale (ESS); the Pittsburgh Sleep Quality Index (PSQI) and the 10-Cognitive Screener (10-CS). HIC was present in 40.6% of CKD patients. Morning chronotype was prevalent in CKD patients (69%) compared to evening-type (17.1%) and significantly different from a paired sample from the general population (p < 0.001). HIC and chronotype were associated with different domains of QoL but not with sleep quality. This study suggests that there is a HIC and that morning chronotype is associated with CKD patients undergoing hemodialysis, with implications for QoL.

Subchronic Arsenite Exposure Induced Atrophy and Erythropoietin Sensitivity Reduction in Skeletal Muscle Were Relevant to Declined Serum Melatonin Levels in Middle-Aged Rats

Arsenic is a kind of widespread environmental toxicant with multiorgan-toxic effects, and arsenic exposure is associated with the occurrence and development of many chronic diseases. The influence of environmental arsenic exposure on skeletal muscle, which is a vital organ of energy and glucose metabolism, has received increasing attention. This study aimed to investigate the types of inorganic arsenic-induced skeletal muscle injury, and the potential regulatory effects of melatonin (MT) and erythropoietin (EPO) in young (3-month-old) and middle-aged (12-month-old) rats. Our results showed that 1 mg/L sodium arsenite exposure for 3 months could accelerate gastrocnemius muscle atrophy and promote the switch of type II fibers to type I fibers in middle-aged rats; however, it did not cause significant pathological changes of gastrocnemius muscle in young rats. In addition, arsenite could inhibit serum MT levels, and promote serum EPO levels but inhibit EPO receptor (EPOR) expression in gastrocnemius muscle in middle-aged rats, while serum MT levels and EPOR expression in gastrocnemius muscle showed an opposite effect in young rats. Importantly, exogenous MT antagonized the arsenite-induced skeletal muscle toxic effect and restored serum EPO and gastrocnemius muscle EPOR expression levels in middle-aged rats. There was a positive correlation among gastrocnemius muscle index, serum MT level, and gastrocnemius muscle EPOR protein level in arsenite-exposed rats. This study demonstrated that inorganic arsenic could accelerate skeletal muscle mass loss and type II fiber reduction in middle-aged rats, which may be related to decreased MT secretion and declined EPO sensitivity in skeletal muscle.

Melatonin: Potential avenue for treating iron overload disorders

Iron overload as a highly risk factor, can be found in almost all human chronic and common diseases. Iron chelators are often used to treat iron overload; however, patient adherence to these chelators is poor due to obvious side effects and other disadvantages. Numerous studies have shown that melatonin has a high iron chelation ability and direct free radical scavenging activity, and can inhibit the lipid peroxidation process caused by iron overload. Therefore, melatonin may become potential complementary therapy for iron overload-related disorders due to its iron chelating and antioxidant activities. Here, the research progress of iron overload is reviewed and the therapeutic potential of melatonin in the treatment of iron overload is analyzed. In addition, studies related to the protective effects of melatonin on oxidative damage induced by iron overload are discussed. This review provides a foundation for preventing and treating iron homeostasis disorders with melatonin.

Effects of short-term administration of melatonin before gonadectomy on oxidative stress, cortisol and sex hormones in male dogs

The aim of this study was to investigate gonadectomy stress, steroid hormones and serotonin in male dogs treated with melatonin before gonadectomy. Twenty-five mixed breed adult dogs were divided into five equal groups. The melatonin and melatonin + gonadectomized groups received melatonin treatment (3 mg/10 Kg, PO, TID) the day before gonadectomy; the gonadectomized and anaesthesia groups did not receive melatonin; and the control group just received the melatonin vehicle. Blood sampling was performed before melatonin administration (day -1) and on days 0 (gonadectomy), 1, 3 and 6 after gonadectomy. Superoxide dismutase and glutathione peroxidase concentrations decreased significantly in gonadectomized dogs compared with dogs treated with melatonin before gonadectomy and intact dogs. Gonadectomy led to a significant decrease in catalase concentration in gonadectomized dogs compared with other study groups. Malondialdehyde levels increased significantly in gonadectomized dogs compared with other groups. Melatonin administration before gonadectomy led to decreased malondialdehyde concentration in gonadectomized and intact dogs compared to the control group. Cortisol concentration increased significantly in gonadectomized dogs compared to the control dogs. Serotonin levels decreased in gonadectomized dogs, but melatonin treatment increased serotonin concentration in gonadectomized and intact dogs. Melatonin treatment before gonadectomy suppressed oxidative stress and the cortisol but increased serotonin level.

A systematic review of the relationship between night shift work and oxidative stress

Night shift workers make up an essential part of the modern workforce. However, night shift workers have higher incidences of late in life diseases and earlier mortality. Night shift workers experience circadian rhythm disruption due to working overnight. Sleep disruption is thought to increase oxidative stress, defined as an imbalance of excess pro-oxidative factors and reactive oxygen species over anti-oxidative activity. Oxidative stress can damage cells, proteins and DNA and can eventually lead to varied chronic diseases such as cancer, diabetes, cardiovascular disease, Alzheimer's and dementia. This review aimed to understand whether night shift workers were at greater risk of oxidative stress. Twelve correlational studies published in 2001-2019 were included in the review that measured the levels of oxidative stress indicators from working a single night shift as well as comparisons between those who regularly work night shifts and only day shifts. All studies had evidence to support the relationship between working night shifts and increased oxidative stress indicators. Specifically, night shift work was associated with increased DNA damage, reduced DNA repair capacity, increased lipid peroxidation, higher levels of reactive oxygen species, and to a lesser extent, a reduction in antioxidant defence. These results suggest a potential link between circadian rhythm disruption in night shift workers with oxidative stress and therefore disease. However, this review is limited by having no longitudinal or experimental studies. Further research is required to infer causality. This further research is recommended to promote the long-term health of night shift workers.

Possible benefits of exogenous melatonin for individuals on dialysis: a narrative review on potential mechanisms and clinical implications

Prevention of oxidative stress and inflammation in chronic kidney disease patients (CKD) on dialysis may reduce dialysis-associated complications. Administration of powerful antioxidants may improve the consequences of peritoneal dialysis (PD) and hemodialysis (HD). This narrative review aimed to show the potential therapeutic effects of melatonin (MLT) on the consequences of CKD patients receiving HD or PD. The results of preclinical and clinical studies have proven that CKD and dialysis are accompanied by reduced endogenous MLT levels and related complications such as sleep disorders. Enhanced oxidative stress, inflammation, cellular damages, and renal fibrosis, along with dysregulation of the renin-angiotensin system (RAS), have been observed in CKD and patients on dialysis. Results of studies have revealed that the restoration of MLT via the exogenous source may regulate oxidative stress, inflammation, and RAS functions, inhibit fibrosis, and improve complications in patients with long-term dialysis patients. In summary, treatment of patients with CKD and dialysis with exogenous MLT is suggested as a practical approach in reducing the outcomes and improving the quality of life in patients via antioxidant, anti-inflammatory, and anti-fibrotic signaling pathways. Therefore, this hormone can be considered in clinical practice to manage dialysis-related complications.

Melatonin protects against tenofovir-induced nephrotoxicity in rats by targeting multiple cellular pathways

Nephrotoxicity is a dose-limiting side effect of long-term use of tenofovir, a reverse transcriptase inhibitor that is used for the treatment of HIV infection and chronic hepatitis B infection. Identifying an agent that prevents tenofovir disoproxil fumarate (TDF)-induced renal injury can lead to its better tolerance, and a more effective treatment can be achieved. The present study is aimed at investigating whether melatonin, a potent antioxidant and anti-inflammatory agent, protects against TDF nephrotoxicity in rats and to determine its cellular targets. Rats were divided into groups and treated as follows. Group I (control): Rats in this group (n = 6) received sterile water only by gavage for 35 days. Group II: Rats (n = 6) in this group received 600 mg/kg body weight TDF in sterile water by gavage for 35 days. Group III: Rats (n = 6) in this group received once daily 20 mg/kg bodyweight melatonin i.p. 2 h before the administration of 600 mg/kg body weight TDF in sterile water by gavage for 35 days. Group IV: Rats were pretreated daily with 20 mg/kg body weight melatonin i.p. 2 h before the administration of sterile water by gavage. All the rats were sacrificed on the 36th day, after overnight fast. Melatonin pretreatment protected the rats against TDF nephrotoxicity both histologically and biochemically. Biochemically, melatonin pretreatment attenuated TDF-induced, oxidative stress, nitrosative stress, mitochondrial pathway of apoptosis, PARP overactivation and preserved proximal tubular function (p < 0.01). This suggests that melatonin may be useful in ameliorating TDF nephrotoxicity.

Melatonin ameliorates the drug induced nephrotoxicity: Molecular insights

BACKGROUND

Drug-induced nephrotoxicity is a frequent adverse event that can lead to acute or chronic kidney disease and increase the healthcare expenditure. It has high morbidity and mortality incidence in 40-70% of renal injuries and accounts for 66% cases of renal failure in elderly population.

OBJECTIVE

Amelioration of drug-induced nephrotoxicity has been long soughed to improve the effectiveness of therapeutic drugs. This study was conducted to review the melatonin potential to prevent the pathogenesis of nephrotoxicity induced by important nephrotoxic drugs.

METHODS

We analyzed the relevant studies indexed in Pubmed, Medline, Scielo and Web of science to explain the molecular improvements following melatonin co-administration with special attention to oxidative stress, inflammation and apoptosis as key players of drug-induced nephrotoxicity.

RESULTS

A robust consensus among researchers of these studies suggested that melatonin efficiently eradicate the chain reaction of free radical production and induced the endogenous antioxidant enzymes which attenuate the lipid peroxidation of cellular membranes and subcellular oxidative stress in drug-induced nephrotoxicity. This agreement was further supported by the melatonin role in disintegration of inflammatory process through inhibition of principle pro-inflammatory or apoptotic cytokines such as TNF-α and NF-κB. These studies highlighted that alleviation of drug-induced renal toxicity is a function of melatonin potential to down regulate the cellular inflammatory and oxidative injury process and to stimulate the cellular repair or defensive mechanisms.

CONCLUSION

The comprehensive nephroprotection and safer profile suggests the melatonin to be a useful adjunct to improve the safety of nephrotoxic drugs.

Endothelial Injury Markers With High-dose IntravenousIron Therapy in Renal Failure

Endothelial injury is prevalent in patients with chronic renal failure (CRF) and may be exacerbated by commonly used intravenous (IV) iron therapy. The effects of high-dose IV iron sucrose treatment (200 mg daily in 250 mL of 0.9% saline, administered over 1 hour, median treatment duration 5 days) on circulating endothelium and/or tissue injury markers such as hepatocyte growth factor, thrombomodulin, von Willebrand factor, and C-reactive protein levels were studied. The markers were determined in 24 anemic (mean hemoglobin 9.48 g/dL) pre-dialysis (median creatinine clearance 21.5 mL/min) patients with CRF and defined absolute and/or functional iron deficiency. The measurements were performed before iron administration and 24 hours after the last infusion. All the markers remained unchanged following the IV iron therapy (all p < 0.172); no thrombotic or other adverse effects were observed. In conclusion, the above high-dose IV iron sucrose supplementation does not cause evident endothelial or other tissue injury in patients with CRF, and is clinically safe.

Melatonin improves sleep quality in hemodialysis patients

Disturbed sleep is common in end-stage renal disease (ESRD). Exogenous melatonin has somniferous properties in normal subjects and can improve sleep quality (SQ) in several clinical conditions. Recent studies have shown that melatonin may play a role in improving sleep in patients undergoing dialysis. The goal of the present study was to assess the effect of exogenous melatonin administration on SQ improvement in daytime hemodialysis patients. Lipid profile and the required dose of erythropoietin (EPO) are also reported as secondary outcomes. In a 6-week randomized, double-blind cross-over clinical trial, 3 mg melatonin or placebo was administered to 68 patients at bedtime. A 72-h washout preceded the switch from melatonin to placebo, or vice versa. SQ was assessed by the Pittsburgh sleep quality index (PSQI). Sixty-eight patients completed the study protocol and were included in the final analysis. Melatonin treatment significantly improved the global PSQI scores (P < 0.001), particularly subjective SQ (P < 0.001), sleep efficiency (P = 0.005) and sleep duration (P < 0.001). No differences in sleep latency and daytime sleepiness were observed. Melatonin also increased the high-density lipoprotein (HDL) cholesterol (P = 0.003). The need for EPO prescription decreased after melatonin treatment (P < 0.001). We conclude that melatonin can improve sleep in ESRD. The modest increase in HDL cholesterol and decrease in the EPO requirement are other benefits associated with this treatment

Pomegranate juice intake attenuates the increase in oxidative stress induced by intravenous iron during hemodialysis

The hemodialysis (HD) procedure induces oxidative stress (OS), which is further aggravated by intravenous (IV) iron administration, aimed at correcting anemia of patients with HD. We have recently shown that 1 year of pomegranate juice (PJ) intake attenuated OS and inflammation in patients with HD. In the current study, we hypothesized that a single dose of PJ can attenuate the enhanced OS and inflammation induced by both the dialysis procedure and IV iron administration during HD session. Twenty-seven patients with HD were randomized to receive PJ or placebo during 1 dialysis session with IV iron. Blood samples were drawn before and after the session to asses OS biomarkers such as advanced oxidation protein products and myeloperoxidase (MPO), whereas polymorphonuclear leukocyte (PMNL) counts served as an indirect measure of inflammation. At the end of the dialysis session, an increase in advanced oxidation protein products and MPO levels as well as a decrease in PMNLs counts were observed in the placebo group, whereas no significant changes occurred in the PJ group. The postdialysis increase in MPO levels in the placebo group is a direct result of PMNL degranulation, associated with postdialysis decrease in PMNL counts. Degranulation of PMNLs leads to the release of other cell moieties, such as inflammatory mediators and proteases that enhance inflammation. We conclude that PJ intake attenuated the increase in systemic OS and inflammation induced by IV iron administration during the dialysis session. These beneficial effects illuminate the previously observed attenuation in OS and inflammation in patients with HD on prolonged PJ intake.

Melatonin: comprehensive profile

This chapter includes the aspects of melatonin. The drug is synthesized in the pineal gland starting from tryptophane or synthetically by using indole as starting material. Melatonin has been used as an adjunct to interleukin-2 therapy for malignant neoplasms, as contraceptive, in the management of various forms of insomnia, to alleviate jet lag following long flights, and finally as free radical scavenger and hence as an antioxidant and an anti-inflammatory. The chapter discusses the drug metabolism and pharmacokinetics and presents various method of analysis of this drug such as biological analysis, spectroscopic analysis, and chromatographic techniques of separation. It also discusses its physical properties such as solubility characteristics, X-ray powder diffraction pattern, and thermal methods of analysis. The chapter is concluded with a discussion on its biological properties such as activity, toxicity, and safety.

Ischemia modified albumin and carbonyl protein as potential biomarkers of protein oxidation in hemodialysis

OBJECTIVE

The aim of this study was to evaluate the effect of HD on ischemia modified albumin (IMA) and protein carbonyl groups in order to investigate the role of IMA as a marker of protein oxidation.

DESIGN AND METHODS

This study was conducted with 23 chronic hemodialysis patients. The serum IMA levels and protein carbonyl groups were measured immediately before hemodialysis (pre-HD) and after the end of hemodialysis (post-HD).

RESULTS

IMA concentrations were significantly higher in post-HD than those of the pre-HD and carbonyl protein concentrations were higher in post-HD in comparison with pre-HD. A significant correlation was observed between IMA and carbonyl protein levels.

CONCLUSIONS

The increase of IMA levels and protein carbonyl groups post-HD could be attributed to the increase of oxidative stress associated with HD, and IMA appears to be an important biomarker for assessing protein oxidation after HD.

Role of hesperetin (a natural flavonoid) and its analogue on apoptosis in HT-29 human colon adenocarcinoma cell line--a comparative study

Colon cancer is one of the serious health problems in most developed countries and its incidence rate is increasing in India. Hesperetin (HN) (3',5,7-trihydroxy-4'-methoxyflavonone) and hesperetin analogue (HA) were tested for their apoptosis inducing ability. Methyl thiazolyl tetrazolium assay revealed a dose as well as duration-dependent reduction of HT-29 (colon adenocarcinoma) cellular growth in response to HN and HA treatment. At 24 h 70 μM of HN and 32 μM of HA showed 50% reduction of HT-29 cellular growth. Acridine orange/ethidium bromide staining showed apoptotic features of cell death induced by HN and HA. Rhodamine 123 staining showed significant reduction in mitochondrial membrane potential induced by HN and HA. HN and HA induced DNA damage was confirmed by comet tail formation. Lipid peroxidation markers (TBARS) and protein oxidation marker (PCC) were significantly elevated in HN and HA treated groups. Enzymic antioxidants such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) were slightly decreased in their activities compared to control (untreated HT-29 cells). Results of Western blot analysis of apoptosis associated genes revealed an increase in cytochrome C, Bax, cleaved caspase-3 expression and a decrease in Bcl-2 expression. These findings indicate that HN and HA induce apoptosis on HT-29 via Bax dependent mitochondrial pathway involving oxidant/antioxidant imbalance.

Erythropoietin Increases Expression and Function of Transient Receptor Potential Canonical 5 Channels

Hypertension is a common complication in hemodialysis patients during erythropoietin (EPO) treatment. The underlying mechanisms of EPO-induced hypertension still remain to be determined. Increased transient receptor potential canonical (TRPC) channels have been associated with hypertension. Now, TRPC gene expression was investigated using quantitative real-time RT-PCR and immunoblotting in cultured human endothelial cells and in monocytes from hemodialysis patients. EPO dose-dependently increased TRPC5 mRNA in endothelial cells. EPO increased TRPC5 mRNA stability, that is, EPO prolonged the half-life period for TRPC5 mRNA from 16 hours (control) to 24 hours ( P <0.05). The poly(A) tail length was measured by rapid amplification of cDNA ends-poly(A) test. Increased TRPC5 mRNA stability was attributed to longer 3′ poly(A) tail lengths after EPO administration. EPO also significantly increased TRPC5 channel protein abundance by 70% ( P <0.05). Whole-cell patch clamp showed that angiotensin II–induced, TRPC5-mediated currents were dramatically increased in endothelial cells treated with EPO. Fluorescent dye techniques confirmed that increased calcium influx after EPO treatment was abolished after TRPC5 knockdown ( P <0.05). EPO also significantly increased intracellular reactive oxygen species production. Knockdown of TRPC5 alleviated EPO-induced reactive oxygen species generation in endothelial cells ( P <0.05). In vivo, EPO-treated hemodialysis patients showed significantly increased amounts of TRPC5 mRNA in monocytes compared with EPO-free hemodialysis patients (6.0±2.4 [n=12] versus 1.0±0.5 [n=9]; P <0.01). Patients undergoing EPO treatment also showed significantly elevated systolic blood pressure (160±7 versus 139±6 mm Hg; P <0.05). Our findings suggest that upregulated functional TRPC5 gene may be one cause of EPO-induced hypertension in patients with chronic kidney disease.

A new perspective in Oral health: potential importance and actions of melatonin receptors MT1, MT2, MT3, and RZR/ROR in the oral cavity

BACKGROUND

Melatonin is involved in many physiological processes in mammals, amongst others; it is implicated in sleep-wake regulation. It has antioxidant and anti-inflammatory properties. It also acts as an immunomodulator, stimulates bone metabolism and inhibits various tumours. Additionally an abnormal melatonin rhythm may contribute to depression and insomnia. The mechanisms of action of melatonin include the involvement of membrane receptors (MT1, MT2), cytosolic binding sites (MT3 and calmodulin), and nuclear receptors of the RZR/ROR family. Melatonin also has receptor-independent activity and can directly scavenge free radicals. The current review addresses the functions of melatonin in the oral cavity in relation to its receptors.

METHODS

An extensive search was conducted on the following scientific databases Pub Med, Science Direct, ISI Web of Knowledge and Cochrane database in order to review all pertinent literature.

RESULTS

Melatonin from the blood into the saliva may play an important role in suppressing oral diseases. It may have beneficial effects in periodontal disease, herpes and oral cancer, amongst others.

CONCLUSIONS

Melatonin contributes to protecting of oral cavity from tissue damage due to its action of different receptors. From the reviewed literature it is concluded that experimental evidence suggests that melatonin can be useful in treating several common diseases of the oral cavity. Specific studies are necessary to extend the therapeutic possibilities of melatonin to other oral diseases.

Oxidative stress, renal anemia, and its therapies: is there a link?

In chronic kidney disease, anemia and oxidative stress are common features and both are involved in increasing morbidity and mortality. However, their relationship is still a matter of debate. This article is a review of published data and our experience and is intended to debate the pro and contra arguments concerning renal anemia and its 2 main therapeutic approaches, that are, erythropoietin and intravenous iron supplementation, as additional causes of oxidative stress in end-stage renal disease patients. To date, it seems more likely that renal anemia itself is the main contributor, and intravenous iron further enhances oxidative stress associated with chronic kidney disease. Future randomized prospective trials, with "hard" clinical end-points, are needed to establish the real effect of biochemical pro-oxidative changes on patient's outcome.

Synergistic neuroprotective effect of combined low concentrations of galantamine and melatonin against oxidative stress in SH-SY5Y neuroblastoma cells

Melatonin is a potent free radical scavenger, antioxidant and neuroprotective drug. On the other hand, galantamine is a cholinergic drug with antioxidant and neuroprotective properties linked to inhibition of acetylcholinesterase and allosteric modulation of nicotinic receptors. This investigation evaluated a possible synergistic neuroprotective effect of subeffective concentrations of combined galantamine and melatonin. Human neuroblastoma SH-SY5Y cells were subjected to a mitochondrial oxidative stress, by blockade of mitochondrial complexes I and V with rotenone and oligomycin-A (R/O); cells were treated for 24 hr with R/O. This caused 40% of the cell to die as measured by lactate dehydrogenase (LDH) release. Cell incubation with increasing concentrations of galantamine (10-300 nm) or melatonin (0.3-10 nm) for 24 hr, followed by a 24-hr period with R/O, caused a concentration-dependent protection; maximum protection was achieved with 300 nm galantamine (56% protection) and 10 nm melatonin (50% protection). Combination of subeffective concentrations of melatonin (0.3 nm) and galantamine (30 nm) caused a synergistic and significant protection that was similar to the maximum protection afforded by effective concentrations of melatonin or galantamine alone. This protective effect was completely reversed when nicotinic and melatonin receptors were blocked respectively by mecamylamine and luzindole. The neuroprotective effect was prevented by chelerythrine, LY294002, and Sn (IV) protoporphyrin IX dichloride (SnPP), indicating the participation of the PKC/PI3K/Akt activation and induction of the antioxidant enzyme heme oxygenase-1. The synthesis of novel multitarget compounds having in a single molecule the combined neuroprotective properties of galantamine and melatonin could be a new strategy for potential therapeutic agents in neurodegenerative diseases.

Involvement of mitochondria mediated pathways in hepatoprotection conferred by Fumaria parviflora Lam. extract against nimesulide induced apoptosis in vitro

Nimesulide, a popular nonsteroidal anti-inflammatory drug, has been associated with serious hepatotoxicity. Reactive oxygen species (ROS) and mitochondrial perturbations have been implicated in drug induced hepatotoxicity, although their role in the pathway needs exploration. Study was undertaken to elucidate the effect of Fumaria parviflora Lam. (Fp) on nimesulide induced cell death in primary rat hepatocyte cultures. Fp extract treated cells showed increased viability as compared to nimesulide stressed cells as assessed by MTT assay. LDH leakage increased significantly at 500microM nimesulide, and the data suggested that apoptosis was the predominant mechanism responsible for cell death. Nimesulide induced apoptosis was further confirmed by DNA fragmentation and chromatin condensation. Nimesulide exposure increased intracellular ROS, translocation of Bax and Bcl2 followed by mitochondrial depolarization and cytochrome c (Cyt c) release along with caspase-9/-3 activity confirming involvement of mitochondria in nimesulide induced apoptosis. Events like membrane depolarization of mitochondria, expression of Bax, Bcl2, externalization of phosphatidyl serine are substantially reversed by the pre-treatment of Fp extract. Thus, the study indicates that Fp extract modulates critical events regulating pro and anti-apoptotic proteins in mitochondria dependent apoptosis induced by nimesulide.

Iron behaving badly: inappropriate iron chelation as a major contributor to the aetiology of vascular and other progressive inflammatory and degenerative diseases

BACKGROUND

The production of peroxide and superoxide is an inevitable consequence of aerobic metabolism, and while these particular 'reactive oxygen species' (ROSs) can exhibit a number of biological effects, they are not of themselves excessively reactive and thus they are not especially damaging at physiological concentrations. However, their reactions with poorly liganded iron species can lead to the catalytic production of the very reactive and dangerous hydroxyl radical, which is exceptionally damaging, and a major cause of chronic inflammation.

REVIEW

We review the considerable and wide-ranging evidence for the involvement of this combination of (su)peroxide and poorly liganded iron in a large number of physiological and indeed pathological processes and inflammatory disorders, especially those involving the progressive degradation of cellular and organismal performance. These diseases share a great many similarities and thus might be considered to have a common cause (i.e. iron-catalysed free radical and especially hydroxyl radical generation).The studies reviewed include those focused on a series of cardiovascular, metabolic and neurological diseases, where iron can be found at the sites of plaques and lesions, as well as studies showing the significance of iron to aging and longevity. The effective chelation of iron by natural or synthetic ligands is thus of major physiological (and potentially therapeutic) importance. As systems properties, we need to recognise that physiological observables have multiple molecular causes, and studying them in isolation leads to inconsistent patterns of apparent causality when it is the simultaneous combination of multiple factors that is responsible.This explains, for instance, the decidedly mixed effects of antioxidants that have been observed, since in some circumstances (especially the presence of poorly liganded iron) molecules that are nominally antioxidants can actually act as pro-oxidants. The reduction of redox stress thus requires suitable levels of both antioxidants and effective iron chelators. Some polyphenolic antioxidants may serve both roles.Understanding the exact speciation and liganding of iron in all its states is thus crucial to separating its various pro- and anti-inflammatory activities. Redox stress, innate immunity and pro- (and some anti-)inflammatory cytokines are linked in particular via signalling pathways involving NF-kappaB and p38, with the oxidative roles of iron here seemingly involved upstream of the IkappaB kinase (IKK) reaction. In a number of cases it is possible to identify mechanisms by which ROSs and poorly liganded iron act synergistically and autocatalytically, leading to 'runaway' reactions that are hard to control unless one tackles multiple sites of action simultaneously. Some molecules such as statins and erythropoietin, not traditionally associated with anti-inflammatory activity, do indeed have 'pleiotropic' anti-inflammatory effects that may be of benefit here.

CONCLUSION

Overall we argue, by synthesising a widely dispersed literature, that the role of poorly liganded iron has been rather underappreciated in the past, and that in combination with peroxide and superoxide its activity underpins the behaviour of a great many physiological processes that degrade over time. Understanding these requires an integrative, systems-level approach that may lead to novel therapeutic targets.

Intravenous iron exacerbates oxidative DNA damage in peripheral blood lymphocytes in chronic hemodialysis patients

Patients undergoing maintenance hemodialysis have elevated markers of oxidative stress, but the reasons for this are not fully understood. Intravenous administration of iron, which many of these patients receive, may provoke the generation of bioactive iron, which enhances oxidative stress and lipid peroxidation. In this study, 110 hemodialysis patients were randomly assigned to five groups that were administered single intravenous doses of iron sucrose, ranging from 20 to 500 mg. A time- and dosage-dependent rise in lymphocyte 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels in lymphocyte DNA, a marker of oxidative DNA damage, with a significant increase at 2 h after intravenous iron of > or = 200 mg (P < 0.05). Four weeks later, patients were randomly assigned to weekly iron sucrose (100 mg of elemental iron) or saline for 12 wk, and 89 patients completed the study. Mean lymphocyte 8-OHdG content was significantly higher in patients receiving intravenous iron compared with control subjects (P < 0.05), especially in those with ferritin levels > 500 microg/L. In addition, flow cytometric techniques revealed increased production of reactive oxygen species in lymphocytes among those treated with intravenous iron. Treatment with intravenous iron but not saline was also associated with decreased plasma ascorbate and alpha-tocopherol levels and increased oxidized glutathione/reduced glutathione ratio (P < 0.05). In summary, intravenous iron sucrose provokes oxidative damage to peripheral blood lymphocyte DNA in hemodialysis patients, especially among those with high levels of ferritin.

Anemia and anemia correction: surrogate markers or causes of morbidity in chronic kidney disease?

Observational studies have shown a strong positive correlation between the severity of anemia and the risk of poor outcomes in patients with chronic kidney disease (CKD). This observation was initially taken to imply that adverse outcomes in CKD are caused by anemia. However, the assumption of causality ignores the possibility that anemia and adverse outcomes might be unrelated and that both are caused by underlying inflammation, oxidative stress and comorbid conditions. Randomized clinical trials of anemia correction have revealed an increased risk of adverse cardiovascular outcomes in patients assigned to normal, rather than subnormal, hemoglobin targets. As a result, correction of anemia is now considered potentially hazardous in patients with CKD. Notably, individuals who did not reach the target hemoglobin level in the clinical trials, despite receiving high doses of erythropoietin and iron, experienced a disproportionately large share of the adverse outcomes. These observations point to overdose of erythropoietin and iron, rather than anemia correction per se, as the likely culprit. This Review explores the reasons for the apparent contradiction between the findings of observational studies and randomized clinical trials of anemia treatment in CKD. I have focused on data from basic and translational studies, which are often overlooked in the design and interpretation of clinical studies and in the formulation of clinical guidelines.

Utility of melatonin to treat surgical stress after major vascular surgery--a safety study

Surgery for abdominal aortic aneurysm is associated with elevated oxidative stress. As an antioxidant in animal and human studies, melatonin has the potential of ameliorating some of this oxidative stress, but melatonin has never been administered to adults during surgery for the purpose of reducing oxidative damage. The aim of this pilot study was to evaluate the safety of various doses of melatonin administered during or after surgery and to monitor the changes in biomarkers of oxidative stress and inflammation during the pre-, intra-, and postoperative period. Six patients undergoing aortic surgery received 10 (n = 2), 30 (n = 2) or 60 (n = 2) mg melatonin intravenously in the intraoperative phase and 10 mg orally for three nights after surgery. Patients were monitored for hemodynamic parameters during and after surgery. Any unexpected events during the hospitalization were registered. Blood samples were collected preoperatively and at 5 min, 6 hr and 24 hr after clamp removal or after re-circulation of the first leg and the samples were analyzed for malondialdehyde (MDA), ascorbic acid (AA), dehydroascorbic acid (DHA), and interleukin-6 (IL-6). Troponin I (TpI) and C-reactive protein (CRP) were also measured for 4 days after surgery. Melatonin administration did not change hemodynamic parameters (mean arterial pressure or pulse rate) during surgery (P = 0.499 and 0.149, respectively), but oxidative stress parameters (MDA and AA) decreased significantly (P = 0.014 and 0.001, respectively). There was a significant increase in the inflammatory parameters (IL-6 and CRP) (P = 0.001 and 0.001, respectively) and an increase in TpI (P = 0.009) as a consequence of surgery. These were not influenced by melatonin treatment. Treatment of patients undergoing major aortic surgery with melatonin intravenously up to 60 mg in the intraoperative phase was safe and without complications. Melatonin may decrease oxidative damage resulting from surgery, but randomized clinical trials are required before definitive conclusions can be drawn regarding the clinical benefit of melatonin in surgical situations.

Melatonin ameliorates oxidative stress, inflammation, proteinuria, and progression of renal damage in rats with renal mass reduction

The progressive deterioration of renal function and structure resulting from renal mass reduction are mediated by a variety of mechanisms, including oxidative stress and inflammation. Melatonin, the major product of the pineal gland, has potent_antioxidant and anti-inflammatory properties, and its production is impaired in chronic renal failure. We therefore investigated if melatonin treatment would modify the course of chronic renal failure in the remnant kidney model. We studied rats followed 12 wk after renal ablation untreated (Nx group, n = 7) and treated with melatonin administered in the drinking water (10 mg/100 ml) (Nx + MEL group, n = 8). Sham-operated rats (n = 10) were used as controls. Melatonin administration increased 13-15 times the endogenous hormone levels. Rats in the Nx + MEL group had reduced oxidative stress (malondialdehyde levels in plasma and in the remnant kidney as well as nitrotyrosine renal abundance) and renal inflammation (p65 nuclear factor-kappaB-positive renal interstitial cells and infiltration of lymphocytes and macrophages). Collagen, alpha-smooth muscle actin, and transforming growth factor-beta renal abundance were all increased in the remnant kidney of the untreated rats and were reduced significantly by melatonin treatment. Deterioration of renal function (plasma creatinine and proteinuria) and structure (glomerulosclerosis and tubulointerstitial damage) resulting from renal ablation were ameliorated significantly with melatonin treatment. In conclusion, melatonin administration improves the course of chronic renal failure in rats with renal mass reduction. Further studies are necessary to define the potential usefulness of this treatment in other animal models and in patients with chronic renal disease.

Long-term erythropoietin therapy does not affect endothelial markers, coagulation activation and oxidative stress in haemodialyzed patients

INTRODUCTION

Although the general improvement caused by recombinant human erythropoietin (rHuEPO) in the correction of uraemic anaemia cannot be questioned, some data suggest that the changes in the haemostasis, endothelial function and oxidative stress (SOX) are induced. The aim of the present study was to investigate the effect of one-year rHuEPO therapy on the coagulation activation, endothelial injury markers and SOX in haemodialysis (HD) patients.

MATERIALS AND METHODS

Assessment of coagulation activation pathway: tissue factor (TF), its inhibitor (TFPI) and prothrombin fragment 1+2 (F1+2); endothelial injury markers: von Willebrand factor antigen (vWF:Ag) and thrombomodulin (TM); and several parameters related to SOX: total peroxide, Cu/Zn superoxide dismutase (Cu/Zn SOD) and autoantibodies to oxidized LDL (OxLDL-Ab) levels were performed in stable HD patients, treated for 12 months with rHuEPO (n=18; mean dose 113.5+/-41 U/kg/week) or not (with Hg<10 g/dl, n=8 and with Hg>10 g/dl, n=12), none of them on iron therapy.

RESULTS

Patients with Hg<10 g/dl had a significantly lower erythrocytes count, Ht and Hg levels than those with Hg>10 g/dl and those on rHuEPO therapy. Long-term rHuEPO therapy does not affect coagulation pathway and SOX markers. Treatment with this hormone resulted in a tendency to decrease TM and vWF:Ag concentrations, however these changes did not reach a statistical significance.

CONCLUSIONS

These results suggest that one-year rHuEPO therapy seems to exert no additional influence on coagulation activation, endothelial cell damage/activation markers and oxidative stress in patients undergoing regular HD in the absence of concomitant iron supplementation and irrespective from haemoglobin levels.

Long-term erythropoietin therapy does not affect metalloproteinases and their inhibitor levels, oxidative stress and inflammation in hemodialyzed patients

BACKGROUND

Matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) play an important role in the atherosclerosis. Recombinant human erythropoietin (EPO) has become widely used to treat anemic hemodialyzed (HD) patients; however, an increased mortality has been reported for HD patients with cardiovascular disease when randomly assigned to normal hematocrit by EPO. Therefore, we conducted a study examining the effect of EPO on MMPs/TIMPs system, oxidative stress and inflammation in these patients.

METHODS

Assessment of MMP-2, MMP-9, TIMP-1 and TIMP-2 were performed in 20 stable HD patients and 15 healthy controls. Additionally, the effects of EPO on malondialdehyde (MDA)--a marker of SOX and C-reactive protein (CRP) levels--as a marker of inflammation were also investigated. Of the 20 patients, 10 were receiving EPO therapy [HD-EPO(+)] for 12 months or more and 10 were not receiving EPO therapy [HD-EPO(-)]. Both groups were not receiving iron supplementation.

RESULTS

All parameters, with the exception of MMP-9, were lower in the healthy subjects compared with the HD subjects, irrespective of EPO administration. There was no difference in MMPs/TIMPs system, MDA and C-reactive levels between HD-EPO(+) and HD-EPO(-) patients.

CONCLUSION

Erythropoietin therapy did not influence MMPs/TIMPs system, inflammation, or SOX in a low-risk HD patient population, in the absence of concomitant iron supplementation and mean Hg levels within target.

Impact of iron sucrose therapy on leucocyte surface molecules and reactive oxygen species in haemodialysis patients

BACKGROUND

It has been suggested that iron increases oxidative stress and that an excess of iron contributes to cardiovascular disease and infections in haemodialysis patients. In the present study, the effects of parenterally administered iron on leucocyte surface molecule expression and the production of reactive oxygen species (ROS) were evaluated.

METHODS

Ten chronic haemodialysis (HD) patients without iron overload were studied. To each patient, four different regimens were applied: placebo; iron sucrose, either 30 or 100 mg, administered via the outflow dialyser line; and 100 mg of iron sucrose infused via the inflow dialyser line. Blood was sampled at different time points: before, during and after infusion and immediately before the next dialysis session. Levels of CD11b and CD45 expression on granulocytes and of CD11b, CD14 and CD36 on monocytes were determined using flow cytometric analysis. The generation of ROS was quantified using chemiluminescence with and without ex vivo stimulation by phorbol myristate acetate (PMA).

RESULTS

No significant differences among the four different treatment regimes were found, neither in chemilumescence activity nor in the expression of CD11b and CD45 on granulocytes, and of CD11b, CD14 and CD36 on monocytes.

CONCLUSIONS

Our results suggest that parenteral infusion of iron sucrose during haemodialysis in patients who have no signs of iron overload has no significant effect on the expression of leucocyte surface molecules and does not increase production of ROS.

Melatonin corrects reticuloendothelial blockade and iron status in haemodialysed patients

AIM

Treatment of anaemia in haemodialysed patients in the setting of inflammation usually displays high levels of serum ferritin (>800 ng/mL) and low transferrin saturation (TSAT) (<20%) despite i.v. iron supplementation, thus proving iron trapping in the reticuloendothelial system. Melatonin has been reported to reduce cytokine production and, in dialysis patients, to prevent oxidative stress resulting from iron and erythropoietin treatment.

METHOD

In this study, we evaluated a group of 10 patients undergoing haemodialysis who displayed elevated serum ferritin (981 +/- 44.6 ng/mL) and TSAT <20% (15.6 +/- 3.8%) after having received 1.2 g of i.v. iron dextran over a period of 8 weeks. These patients received oral melatonin, 6 mg/day at night for 30 days.

RESULTS

After this treatment, all of them markedly increased TSAT values, reaching 35.5 +/- 6.7% (P < 0.0001 vs basal values). In addition, ferritin values decreased to 754.4 +/- 263.7 ng/mL (P < 0.05), and serum iron dramatically increased in all of the patients under study (42.4 +/- 9.4 vs 109.7 +/- 24.3 microg/dL; P < 0.0001). Values for haematocrit (28.6 +/- 2.7 vs 31.9 +/- 3.57%; P < 0.05) and haemoglobin (9.19 +/- 0.97 vs 10.04 +/- 1.29 g/dL; P < 0.05) were also improved. Measurements were then repeated 2 weeks after melatonin withdrawal, showing an impressive decrease in TSAT (16.4 +/- 5.3%; P < 0.00001) and serum iron (48 +/- 14.7 microg/dL; P < 0.0001) values and an almost significant increase in ferritin values (954.4 +/- 86 ng/mL; P < 0.054).

CONCLUSION

The present study demonstrates that melatonin may strongly correct the reticuloendothelial blockade seen in dialysis patients under an inflammatory status, thus allowing a better management of iron derangements and renal anaemia.

Intravenous iron increases labile serum iron but does not impair forearm blood flow reactivity in dialysis patients

BACKGROUND

There are concerns about adverse vascular effects of intravenous iron by inducing oxidative stress. We therefore examined the effect of a single high dose of intravenous iron on endothelial function and biochemical markers of iron homeostasis.

METHODS

In a randomized, placebo-controlled, double-blind, parallel-group study, forearm blood flow (FBF) was assessed by strain-gauge plethysmography in 38 peritoneal dialysis patients before and after a single intravenous infusion of 300 mg iron sucrose.

RESULTS

Iron infusion increased total (Delta 601 microg/100 mL, CI 507, 696) and non-transferrin-bound iron (Delta 237.2 micromol/L, CI 173.6, 300.8) approximately 10-fold, as well as redox-active iron nearly five-fold (Delta 0.76 micromol/L, CI 0.54, 0.98). After iron infusion basal FBF was 59% higher than after placebo. FBF response to acetylcholine before and after iron infusion was 263 +/- 32% and 310 +/- 33%, corresponding to 304 +/- 43% and 373 +/- 29% in the placebo group, respectively. Before and after iron or placebo infusion, glyceryl-trinitrate increased resting FBF to 232 +/- 22% and 258 +/- 21% in the iron group, and to 234 +/- 18% and 270 +/- 30% in the placebo group. L-N-monomethyl-arginine decreased FBF to 70 +/- 4% and 72 +/- 3% before and after iron, and to 74 +/- 4% and 73 +/- 4% before and after placebo infusions, respectively. Despite higher basal FBF after iron infusion, absolute and relative FBF changes in response to vasoactive substances were not significantly different between iron and placebo groups.

CONCLUSION

Our data suggest that 300 mg intravenous iron sucrose has a vasodilatory effect, but does not impair vascular reactivity in dialysis patients, despite a significant increase in non-transferrin-bound and redox-active iron.

The basic physiology and pathophysiology of melatonin

Melatonin is a methoxyindole synthesized and secreted principally by the pineal gland at night under normal environmental conditions. The endogenous rhythm of secretion is generated by the suprachiasmatic nuclei and entrained to the light/dark cycle. Light is able to either suppress or synchronize melatonin production according to the light schedule. The nycthohemeral rhythm of this hormone can be determined by repeated measurement of plasma or saliva melatonin or urine sulfatoxymelatonin, the main hepatic metabolite. The primary physiological function of melatonin, whose secretion adjusts to night length, is to convey information concerning the daily cycle of light and darkness to body physiology. This information is used for the organisation of functions, which respond to changes in the photoperiod such as the seasonal rhythms. Seasonal rhythmicity of physiological functions in humans related to possible alteration of the melatonin message remains, however, of limited evidence in temperate areas in field conditions. Also, the daily melatonin secretion, which is a very robust biochemical signal of night, can be used for the organisation of circadian rhythms. Although functions of this hormone in humans are mainly based on correlative observations, there is some evidence that melatonin stabilises and strengthens coupling of circadian rhythms, especially of core temperature and sleep-wake rhythms. The circadian organisation of other physiological functions could depend on the melatonin signal, for instance immune, antioxidative defences, hemostasis and glucose regulation. Since the regulating system of melatonin secretion is complex, following central and autonomic pathways, there are many pathophysiological situations where the melatonin secretion can be disturbed. The resulting alteration could increase predisposition to disease, add to the severity of symptoms or modify the course and outcome of the disorder.

Influence of Epoietinum Therapy on the Oxidative Stress in Haemodialysis Patients

BACKGROUND

The causes of oxidative stress in haemodialysis (HD) patients are still controversial. Beside the uraemic state and dialysis-related factors, adjuvant drug therapies such as epoietinum (rHuEpo) and intravenous iron were involved.

METHODS

Several parameters related to oxidative stress were assessed by spectrophotometry in stable HD patients, treated for at least 2 months with epoietinum (n = 14; mean dose = 97.7 +/- 19.1 U/kg/week) or not (n = 15), none of them on iron therapy, and in 13 controls. Plasma thiobarbituric acid-reactive substances (TBARS) were used as markers of reactive species generation. Erythrocyte and plasma antioxidant systems, reflected by non-protein erythrocyte thiols, and erythrocyte enzyme activities -- superoxide dismutase (SOD), glutathione peroxidase, catalase and plasma total thiols, respectively -- were also investigated.

RESULTS

There were no differences between HD subgroups regarding haemoglobin levels. Plasma TBARS was increased in all HD patients as opposed to controls, irrespective of rHuEpo therapy. In addition, no change in antioxidant status parameters between rHuEpo-treated and -untreated patients was observed. Except for SOD, the other antioxidant indices were higher in all HD patients versus controls.

CONCLUSIONS

These results suggest that (1) chronic HD patients appear to have simultaneously enhanced reactive species generation and antioxidative systems efficiency, and (2) epoietinum therapy did not change their oxidative status, at least in the absence of concomitant iron supplementation and at similar haemoglobin levels.

Emerging drugs for renal failure

Renal failure involves a significant impairment of the essential functions of the kidney, which can be either acute with sudden and rapid onset (acute renal failure [ARF]) or chronic with gradual onset (chronic renal failure [CRF]). ARF, if detected early, may be halted or reversed, whereas CRF is generally irreversible. Without treatment or intervention, both forms of renal failure lead to end stage renal failure (ESRF) or end stage renal disease (ESRD), requiring renal replacement therapy (RRT) in the form of dialysis or renal transplantation for survival. However, provision of RRT requires expert teams working in specialised units, making therapy of patients with renal failure expensive; furthermore, RRT is complex, with its own complications. Although pharmacological interventions have shown promise in experimental models, these have not been as successful in the clinical setting (e.g., administration of atrial natriuretic peptide, low-dose dopamine). At present, drugs are administered during CRF to either reduce one of the many risk factors of CRF (e.g., angiotensin-converting enzyme inhibitors, statins) or to deal with the consequences of CRF (e.g., erythropoietin, calcitriol). Recent evidence suggests that some of these interventions may provide further direct beneficial effects via reduction of renal inflammation. Although these interventions have greatly improved the prospects for patients suffering ESRF, the development of novel drugs and therapies with which to reduce the consequences of renal failure and ESRD remain topics of great interest. This article reviews the therapies available for the prevention and management of renal failure in adults and describes, in detail, emerging drugs and novel interventions that may soon become available for the treatment or prevention of ESRF.

Erythropoietin Increases Asymmetric Dimethylarginine in Endothelial Cells: Role of Dimethylarginine Dimethylaminohydrolase

Recombinant human erythropoietin therapy frequently causes hypertension in humans and animals with chronic renal failure. Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of nitric oxide (NO) synthase, and its accumulation has been associated with reducing NO bioavailability and increasing superoxide generation. Whether epoetin beta (EPO) or darbepoetin alpha (NESP) can modify the levels of ADMA in endothelial cells was investigated. Endothelial cells from the third passage were incubated for 24 h in the presence of various concentrations of EPO or NESP (0, 0.1, 1, 10, 50, 100, and 200 U/ml). The levels of ADMA, allantoin, nitrate, and nitrite in conditioned media and the activity of dimethylarginine dimethylaminohydrolase (DDAH), the content of thiols and reactive oxygen species in endothelial cells, were determined. When endothelial cells were exposed to EPO or NESP, ADMA concentration in the cell culture medium increased significantly in a dose-dependent manner versus control. This effect was associated with a reduced activity of DDAH, the enzyme that degrades ADMA. Furthermore, EPO- or NESP-induced accumulation of ADMA was accompanied by a significant reduction of NO synthesis and an increase in oxidative stress. Both allantoin, a marker of oxygen free radical generation, and reactive oxygen species increased significantly after EPO or NESP treatment compared with control. The antioxidant pyrrolidine dithiocarbamate preserved DDAH activity and reduced ADMA accumulation in the same way as the co-incubation with anti-EPO neutralizing antibody. EPO and NESP posttranslationally impair DDAH activity via increased oxidative stress, causing ADMA as an important cardiovascular risk factor to accumulate and inhibit NO synthesis.

Potential risk for infection and atherosclerosis due to iron therapy

Iron is an essential nutrient, but carries potential risks. Iron therapy not only affects the functions of leukocytes, endothelial cells, and cytokine production, but also causes oxidative stress and can support bacterial growth. Intravenous iron therapy may result in nontransferrin-bound iron. This may act as a catalytic agent in the formation of hydroxyl radicals, and thus potentially contribute to cell damage and atherosclerosis. Potential long-term complications of intravenous iron therapy in end-stage renal disease patients include atherosclerosis and infection, particularly in patients with iron overload.

Sodium ferric gluconate causes oxidative stress but not acute renal injury in patients with chronic kidney disease: a pilot study

BACKGROUND

Intravenous (i.v) iron is widely used to treat anaemia in patients with chronic kidney disease (CKD). Although beneficial and usually well tolerated, concerns have been raised about its ability to cause oxidative stress and renal injury.

METHODS

To determine if i.v. iron causes oxidative stress [as assessed by plasma and urine malondialdehye (MDA)] and/or renal injury (as assessed by urinary albumin, total protein and enzymuria), we conducted a prospective, four-way randomized crossover, blinded end-point trial in eight patients with CKD. Two widely used doses of sodium ferric gluconate (125 mg infused over 1 h and 250 mg infused over 2 h) were given with or without the antioxidant N-acetylcysteine (NAC), resulting in four treatment dose-antioxidant/placebo combinations in each patient. Transferrin saturation was measured with urea polyacrylamide gel electrophoresis, MDA by high performance liquid chromatography, and albuminuria and proteinuria by standard clinical methods. Enzymuria was assessed by measurement of N-acetyl-beta-D-glucosaminidase (NAG) excretion by colorimetric assay.

RESULTS

I.v. ferric gluconate infusion at both doses resulted in a marked increase in transferrin saturation and a significant increase in plasma MDA levels. Urinary MDA levels also increased at the higher dose of iron. There was no evidence of acute renal injury, as assessed by albuminuria, proteinuria or enzymuria. Pre-treatment with NAC had no effect on oxidative stress or the above urinary parameters.

CONCLUSIONS

I.v. ferric gluconate caused oxidative stress (as reflected by increased MDA), but this was not associated with biochemical manifestations of acute renal injury.

Oxidative stress from rapid versus slow intravenous iron replacement in haemodialysis patients

METHODS AND RESULTS

Oxidative stress was examined in 19 erythropoietin-treated haemodialysis patients who were receiving 100 mg of iron sucrose every 2 weeks by two intravenous methods, rapid injection and slow infusion. There were no significant differences in incidence of iron oversaturation state between the two methods. Regarding oxidative stress markers, the values of plasma and red blood cell thiobarbituric acid reactive substances (TBARS) expressed in terms of malonyldialdehyde (MDA) equivalents following the two methods did not increase, and the values of area under the curve (AUC) of both markers were not different between both regimens. Also, there were no significant differences in the values of plasma and AUC of anti-oxidant markers including total anti-oxidant status, reduced thiols, and vitamin E among both periods treated with two intravenous iron methods.

CONCLUSION

As such, both intravenous iron methods could be safely used without enhancing oxidative stress in haemodialysis patients. The rapid injection method would be the preferred method of intravenous iron administration because it is more convenient while still retaining the safety profile.

Oxidative stress and renal injury with intravenous iron in patients with chronic kidney disease

BACKGROUND

Intravenous iron is widely prescribed in patients with chronic kidney disease (CKD) and can cause oxidative stress. The relationship of oxidative stress and renal injury in patients with CKD is unknown. Whether renal injury can occur at a time point when transferrin is incompletely saturated is also unclear.

METHODS

We conducted a randomized, open-label, parallel group trial to compare the oxidative stress induced by intravenous administration of 100 mg iron sucrose over 5 minutes and its protection with N-acetylcysteine (NAC) in 20 subjects with stage 3 or 4 CKD. Transferrin saturation was measured with urea polyacrylamide gel electrophoresis, oxidative stress by malondialdehyde (MDA) measurement by high-performance liquid chromatography, and renal injury by enzymuria and proteinuria. Reduced and oxidized glutathione and free radical scavengers as well as urinary monocyte chemoattractant protein-1 were also measured.

RESULTS

Parenteral iron increased plasma concentration and urinary excretion rate of MDA, a biomarker of lipid peroxidation, within 15 to 30 minutes of iron sucrose administration. This was accompanied by enzymuria and increase in proteinuria. In contrast, saturation of transferrin was not maximally seen until 3 hours after the end of infusion. Oxidative stress, enzymuria and proteinuria were transient and were completely resolved in 24 hours. NAC reduced acute generation of systemic oxidative stress but failed to abrogate proteinuria or enzymuria.

CONCLUSION

Intravenous iron produces oxidative stress that is associated with transient proteinuria and tubular damage. The rapid production of oxidative stress even when transferrin is not completely saturation suggests free iron independent mechanism(s) to be operative in producing oxidative stress and transient renal injury. Long-term implications of these findings need further study.

Oxidative stress, renal infiltration of immune cells, and salt-sensitive hypertension: all for one and one for all

Recent evidence indicates that interstitial infiltration of T cells and macrophages plays a role in the pathogenesis of salt-sensitive hypertension. The present review examines this evidence and summarizes the investigations linking the renal accumulation of immune cells and oxidative stress in the development of hypertension. The mechanisms involved in the hypertensive effects of oxidant stress and tubulointerstitial inflammation, in particular intrarenal ANG II activity, are discussed, focusing on their potential for sodium retention. The possibility of autoimmune reactivity in hypertension is raised in the light of the proinflammatory and immunogenic pathways stimulated by the interrelationship between oxidant stress and inflammatory response. Finally, we present some clinical considerations derived from the recognition of this interrelationship.

High-dose parenteral iron sucrose depresses neutrophil intracellular killing capacity

BACKGROUND

Iron is essential for the formation of hemoglobin. During long-term treatment with human recombinant erythropoietin (rhEPO), the majority of end-stage renal disease (ESRD) patients will not respond adequately to rhEPO unless substituted with intravenous iron. However, concern exists about possible detrimental effects of parenteral iron on cellular host defense and iron-mediated increments of oxidative stress.

METHODS

We analyzed phagocytic functions of polymorphonuclear leukocytes (PMN) isolated from 20 ESRD patients on peritoneal dialysis in response to 300 mg of iron sucrose or placebo administered intravenously over two hours in a randomized, double-blind manner. We evaluated Fc gamma R-dependent phagocytosis and killing (primary outcome variable) of opsonized Escherichia coli, Fc gamma R-dependent oxidative burst capacity, and complement receptor 3 (CR3, Mac1, CD11b/CD18)/tumor necrosis factor alpha (TNFalpha)-mediated release of bactericidal lactoferrin before, during, one hour, and two days after administration.

RESULTS

The absolute count and the percentage of E. coli killed by PMN of iron sucrose-treated peritoneal dialysis patients decreased significantly over time in comparison to placebo-treated patients (F = 3.48, df = 4, P = 0.008; F = 3.99, df = 4, P = 0.006, respectively). All secondary outcome variables were not different between both groups over time.

CONCLUSIONS

Killing capacity of PMN isolated from ESRD patients decreases in response to high-dose parenteral iron sucrose, possibly in part explaining reported higher hospitalization rates and lower survival rates of dialysis patients receiving frequent and high-dose parenteral iron.

Melatonin: clinical relevance

This chapter reviews the neural connections between the retinas and the pineal gland and summarizes the role of the light:dark cycle and the biological clock, i.e. the suprachiasmatic nuclei, in regulating pineal melatonin synthesis and secretion. The cellular mechanisms governing the nocturnal production of melatonin are described together with the way in which the misuse of light interferes with the circadian melatonin cycle and the total quantity of the indole generated. The chapter describes the nature of the membrane melatonin receptors and their signal transduction mechanisms in peripheral organs. The clinical implications and potential uses of melatonin in terms of influencing the biological clock (e.g. sleep and jet lag), immune function, and cancer initiation and growth are noted. Additionally, the chapter includes a description of the newly discovered free radical scavenging and antioxidant activities of melatonin; it also includes a list of clinical situations in which melatonin has been used with beneficial effects.

Elevation of blood thioredoxin in hemodialysis patients with hepatitis C virus infection

BACKGROUND

Thioredoxin (TRX) is a stress-inducible thiol-containing protein, which has been shown to be an indicator of oxidative stress in a variety of diseases. The association between oxidative stress and hepatitis C virus (HCV) infection, however, remains unknown in hemodialysis patients.

METHODS

We measured serum TRX levels in 85 hemodialysis patients positive for anti-HCV antibodies (age, 60 +/- 1 years old; hemodialysis duration, 17 +/- 1 years; M/F = 57/28) by enzyme-linked immunosorbent assay (ELISA), and examined whether blood TRX may be associated with HCV-related hepatic injury.

RESULTS

Serum TRX was significantly higher in hemodialysis patients with HCV infection (112.3 +/- 3.7 ng/mL, N = 85) than in those without HCV infection (69.7 +/- 3.3 ng/mL, N = 59) (age, 69 +/- 2 years old; hemodialysis duration, 6 +/- 1 years; M/F = 32/27, P < 0.01) or normal subjects (28.0 +/- 5.4 ng/mL, N = 9). TRX was significantly correlated with time on hemodialysis (r = 0.27, P = 0.01) in HCV-positive patients, while it was associated with the patient's age in HCV-negative patients (r = 0.42, P < 0.01). Blood TRX was significantly correlated with asparate aminotransferase in patients with HCV infection (r = 0.34, P < 0.01) and without HCV infection (r = 0.46, P < 0.01). However, serum TRX was not associated with blood alanine aminotransferase, a relatively specific marker of hepatic cellular damage, in HCV-infected hemodialysis patients. A significant relationship was found between serum ferritin and TRX (r = 0.25, P = 0.02) and malondialdehyde (MDA) values (r = 0.25, P = 002) in HCV-positive patients. Serum TRX was also higher in the patients receiving weekly iron supplement with HCV infection (135.3 +/- 10.2 ng/mL vs. 110.2 +/- 3.9 ng/mL, P = 0.06) and without HCV infection (91.8 +/- 12.1 ng/mL vs. 65.2 +/- 2.7 ng/mL, P < 0.01).

CONCLUSION

There was a greater increase in serum TRX in hemodialysis patients with HCV viremia than without HCV viremia. However, there may not be an association between serum TRX and HCV-related hepatic injury. TRX increased with serum ferritin in HCV-infected patients and further increased by iron infusion. These findings indicate that HCV infection and iron loading may aggravate oxidative stress in dialysis patients.

Carbonyl stress induced by intravenous iron during haemodialysis

BACKGROUND

Anaemic haemodialysis (HD) patients are treated with erythropoietin and intravenous iron for effective erythropoiesis. Since iron is a potent inducer and aggravator of pre-existing oxidative processes in HD patients, this study was aimed to evaluate the acute in vivo effect of two recommended iron doses on protein oxidation during the HD session.

METHODS

Iron gluconate was intravenously administered to HD patients in doses of 62.5 or 125 mg per session. A dialysis session without iron administration served as a control for each patient. Carbonylated fibrinogen and iron profile parameters were monitored before and after each session. Plasma carbonylated fibrinogen levels from healthy subjects and HD patients before dialysis were compared. Protein associated carbonyls were identified in plasma by derivatization with 2,4-dinitrophenylhydrazine followed by western analysis and were quantified by densitometry.

RESULTS

HD patients on maintenance iron showed elevated carbonylated fibrinogen compared with healthy subjects. During a HD session, carbonyls on fibrinogen further increased when 125 mg iron gluconate was administered, but no changes were detected with 62.5 mg iron gluconate or in the absence of iron. The changes in carbonylated fibrinogen during dialysis showed a significant linear correlation with the calculated values of transferrin saturation and free transferrin.

CONCLUSIONS

The significant acute increase in carbonylated fibrinogen with 125 mg iron gluconate suggests that this iron dose should be used with caution. As fibrinogen is highly susceptible to iron-induced oxidation in vivo, it may serve as a marker reflecting acute iron oxidative damage and as a tool in refinement of the existing clinical dose guidelines for intravenous iron therapy.