Oxidative stress induced by iron released from transferrin in low pH peritoneal dialysis solution

Iron increases the profibrotic properties of the senescent peritoneal mesothelial cells

BACKGROUND

Treatment of anemia in peritoneal dialysis patients often requires intravenous iron supplementation. Iron diffuses into the peritoneal cavity and is injurious to the peritoneum. We studied how intermittent exposure to iron changes the properties of the senescent peritoneal mesothelial cells (MC).

METHODS

Replicative senescence was induced in MC in control medium (Con) or in control medium with intermittent exposure to iron isomaltoside 15 µg/dL (Con-IIS). After 10 passages properties of MC from both groups were compared to MC not exposed to replicative senescence.

RESULTS

In senescent MC population doubling time was elongated, intracellular generation of free radicals and staining for β-galactosidase was stronger than in MC not exposed to replicative senescence. All these effects were stronger in MC intermittently exposed to IIS. In these cells intracellular iron content was also higher. Also expression of genes p21 and p53 was stronger in MC intermittently treated with IIS. In senescent cells higher release and expression of IL6 and TGFβ1 was observed and that effect was stronger in MC treated with iron. Senescent MC had reduced fibrinolytic activity, what may predispose to the peritoneal fibrosis. Synthesis of collagen was higher in senescent cells, more in MC treated with iron.

CONCLUSION

MC aging results in change of their genotype and phenotype which lead to their profibrotic effect. Exposure to iron enhances these changes.

High glucose dialysate-induced peritoneal fibrosis: Pathophysiology, underlying mechanisms and potential therapeutic strategies

Peritoneal dialysis is an efficient renal replacement therapy for patients with end-stage kidney disease. However, continuous exposure of the peritoneal membrane to dialysate frequently leads to peritoneal fibrosis, which alters the function of the peritoneal membrane and results in withdrawal from peritoneal dialysis in patients. Among others, high glucose dialysate is considered as a predisposing factor for peritoneal fibrosis in patients on peritoneal dialysis. Glucose-induced inflammation, metabolism disturbance, activation of the renin-angiotensin-aldosterone system, angiogenesis and noninflammation-induced reactive oxygen species are implicated in the pathogenesis of high glucose dialysate-induced peritoneal fibrosis. Specifically, high glucose causes chronic inflammation and recurrent peritonitis, which could cause migration and polarization of inflammatory cells, as well as release of cytokines and fibrosis. High glucose also interferes with lipid metabolism and glycolysis by activating the sterol-regulatory element-binding protein-2/cleavage-activating protein pathway and increasing hypoxia inducible factor-1α expression, leading to angiogenesis and peritoneal fibrosis. Activation of the renin-angiotensin-aldosterone system and Ras-mitogen activated protein kinase signaling pathway is another contributing factor in high glucose dialysate-induced fibrosis. Ultimately, activation of the transforming growth factor-β1/Smad pathway is involved in mesothelial-mesenchymal transition or epithelial-mesenchymal transition, which leads to the development of fibrosis. Although possible intervention strategies for peritoneal dialysate-induced fibrosis by targeting the transforming growth factor-β1/Smad pathway have occasionally been proposed, lack of laboratory evidence renders clinical decision-making difficult. We therefore aim to revisit the upstream pathways of transforming growth factor-beta1/Smad and propose potential therapeutic targets for high glucose-induced peritoneal fibrosis.

Iron and iron-related proteins in COVID-19

COVID-19 can cause detrimental effects on health. Vaccines have helped in reducing disease severity and transmission but their long-term effects on health and effectiveness against future viral variants remain unknown. COVID-19 pathogenesis involves alteration in iron homeostasis. Thus, a contextual understanding of iron-related parameters would be very valuable for disease prognosis and therapeutics.Accordingly, we reviewed the status of iron and iron-related proteins in COVID-19. Iron-associated alterations in COVID-19 reported hitherto include anemia of inflammation, low levels of serum iron (hypoferremia), transferrin and transferrin saturation, and high levels of serum ferritin (hyperferritinemia), hepcidin, lipocalin-2, catalytic iron, and soluble transferrin receptor (in ICU patients). Hemoglobin levels can be low or normal, and compromised hemoglobin function has been proposed. Membrane-bound transferrin receptor may facilitate viral entry, so it acts as a potential target for antiviral therapy. Lactoferrin can provide natural defense by preventing viral entry and/or inhibiting viral replication. Serum iron and ferritin levels can predict COVID-19-related hospitalization, severity, and mortality. Serum hepcidin and ferritin/transferrin ratio can predict COVID-19 severity. Here, serum levels of these iron-related parameters are provided, caveats of iron chelation for therapy are discussed and the interplay of these iron-related parameters in COVID-19 is explained.This synopsis is crucial as it clearly presents the iron picture of COVID-19. The information may assist in disease prognosis and/or in formulating iron-related adjunctive strategies that can help reduce infection/inflammation and better manage COVID-19 caused by future variants. Indeed, the current picture will augment as more is revealed about these iron-related parameters in COVID-19.

N-Acetylcysteine: more than preventing contrast-induced nephropathy in uremic patients-focus on the antioxidant and anti-inflammatory properties

Oxidative stress (OS) has been recognized as a pathophysiologic mechanism underlying the development and progression of chronic kidney disease (CKD). OS, which results from the disturbance of balance among pro-oxidants and antioxidants favoring the pro-oxidants, is present even in early CKD and increases progressively along with deterioration of kidney function to end-stage kidney disease (ESKD). In ESKD, OS is further exacerbated mainly due to dialysis procedures per se and predisposes to increased cardiovascular morbidity and mortality. Therefore, since OS plays a pivotal role in the pathogenesis and progression of atherosclerosis in uremic patients, several strategies aiming to ameliorate OS in these patients have been proposed. Among those, N-acetylcysteine (NAC), a thiol-containing antioxidant agent, has attracted special attention due to its pleiotropic functions and beneficial effect in various OS-related entities including paracetamol overdose and prevention of contrast-induced nephropathy. In this review, we present the currently available literature on the antioxidant and anti-inflammatory properties of NAC in CKD, including hemodialysis and peritoneal dialysis.

Transferrin-mediated increase of labile iron Pool following simulated ischemia causes lipid peroxidation during the early phase of reperfusion

Heart ischemia/reperfusion (I/R) injury is related to iron content. However, the occurrence and mechanism of changes in labile iron pool (LIP) during I/R is debatable. Moreover, the identity of the iron form dominant in LIP during I/R is unclear. Herein, we measured changes of LIP during simulated ischemia (SI) and reperfusion (SR), in which ischemia was simulated in vitro with lactic acidosis and hypoxia. Total LIP did not change in lactic acidosis, whereas LIP, especially Fe³⁺, increased in hypoxia. Under SI, accompanied by hypoxia with acidosis, both Fe²⁺ and Fe³⁺ were significantly increased. Increased total LIP was maintained at 1 h post-SR. However, the Fe²⁺ and Fe³⁺ portion was changed. The increased Fe²⁺ was decreased, and conversely the Fe³⁺ was increased. BODIPY oxidized signal increased and through the time-course these changes correlated with blebbing of cell membrane and SR-induced LDH release. These data suggested lipid peroxidation occurred via Fenton's reaction. The experiments using bafilomycin A1 and zinc protoporphyrin suggested no role of ferritinophagy or heme oxidation in the increase of LIP during SI. The extracellular source, transferrin assessed using serum transferrin bound iron (TBI) saturation showed that the depletion of TBI reduced SR-induced cell damages and additive saturation of TBI accelerated SR-induced lipid peroxidation. Furthermore, Apo-Tf dramatically blocked the increase of LIP and SR-induced damages. In conclusion, Tf-mediated iron induces the increase of LIP during SI, and it causes Fenton reaction-mediated lipid peroxidation during the early phase of SR.

Markers of Oxidative Stress, Inflammation, and Endothelial Dysfunction in Diabetic and Nondiabetic Patients with Chronic Kidney Disease on Peritoneal Dialysis

Chronic kidney disease (CKD) is a low-grade inflammatory state which is accom-panied by elevated markers of oxidative stress, inflammatory, and endothelial dysfunction in patients on peritoneal dialysis (PD). These represent a key triad for the development and progression of atherosclerosis. The present study assessed the markers of oxidative stress, inflammatory and endothelial dysfunction in diabetic and non-diabetic CKD patients on PD. A cross-sectional study was undertaken on 100 CKD patients on PD, of whom 52 patients were nondiabetic and 48 were diabetic patients. Blood samples were estimated for malondialdehyde (MDA) and ferric reducing ability of plasma (FRAP) as markers of oxidative stress; interleukin (IL)-6, high-sensitivity C-reactive protein (hs-CRP), and fibrinogen as inflammatory markers; and markers of endothelial dysfunction such as nitric oxide (NO), carotid wall intimal medial thickness (CIMT), and number of plaques, among others. The MDA levels increased and FRAP levels decreased in both diabetic and nondiabetic CKD patients on PD. The levels of IL-6, hs-CRP, fibrinogen, NO, CIMT, and the number of plaques were significantly higher in diabetic patients than in nondiabetic CKD patients on PD. The lipid profile was significantly atherogenic in diabetic patients compared with nondiabetics CKD patients. The results showed increased oxidative stress, inflammation, and endothelial dysfunction in diabetic patients compared with nondiabetics CKD patients on PD.

Adverse effects of iron toward the peritoneal mesothelial cells are reversible

INTRODUCTION

Evaluation of the effects of the drugs used for iron supplementation on the peritoneal mesothelial cells.

METHODS

Acute effects during18-h incubation of iron sucrose, ferric carboxymaltose, and iron isomaltoside in concentrations 1, 5, and 20 ug/dl on properties of the human peritoneal mesothelial cells in in vitro culture were evaluated, and their reversibility after the following culture for 14 days in the iron-free medium was studied.

RESULTS

All studied compounds reduced viability of mesothelial cells and proliferation rate and increased intracellular oxidative stress and iron content in the cytosol. Secretion of monocyte chemoattractant protein-1 was increased and tissue plasminogen activator (t-PA) decreased. After 14 days of culture in iron-free medium, reversibility of all these effects was observed.

CONCLUSION

Iron compounds impair the functional properties of mesothelial cells in a dose-dependent manner, but these effects are reversible after the following culture of the cells in an iron-free medium.

Polymorphism of Transferrin Gene Impacts the Mediating Effects of Psychotic Symptoms on the Relationship between Oxidative Stress and Cognition in Patients with Chronic Schizophrenia

A series of studies indicated that iron distribution that partly derives from transferrin-bound iron in the peripheral nervous system in the brain may act in processes such as myelination and brain development. However, the relationship between schizophrenia, its psychotic symptoms, and the transferrin (TF) gene has not been systematically explored. Our study aimed to investigate how a particular polymorphism of the transferrin gene, rs3811655, affects the superoxide dismutase (SOD), malondialdehyde (MDA), psychotic symptoms, cognition, or the mediation model between antioxidant enzymes and cognition via symptoms. A total of 564 patients with chronic schizophrenia and 468 healthy control subjects were recruited. The psychotic symptoms and cognition were assessed by the Positive and Negative Syndrome Scale (PANSS) and the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), respectively. Furthermore, the serum SOD, MDA activity, and transferrin gene polymorphism were measured in patients. Our results demonstrated that patients with the G allele possessed more severe negative symptoms, worse cognitive performance with respect to attention, and higher serum Mn-SOD activity. Additionally, the rs3811655 polymorphism may act as a moderator in the association between Cu/Zn-SOD activity and cognition, as well as psychotic symptoms in patients suffering from schizophrenia. According to this study, the single nucleotide polymorphism (SNP) rs3811655 polymorphism may fail to contribute to the susceptibility of schizophrenia in an individual but is involved in the iron-induced oxidative stress disturbance and cognitive impairment in schizophrenia. This deepens our understanding of the critical role of iron-induced oxidative stress that might underlie the pathophysiology of schizophrenia.

Could Antioxidant Supplementation Delay Progression of Cardiovascular Disease in End-Stage Renal Disease Patients?

In end-stage renal disease patients, the leading causes of mortality are of cardiovascular (CV) origin. The underlying mechanisms are complex, given that sudden heart failure is more common than acute myocardial infarction. A contributing role of oxidative stress is postulated, which is increased even at early stages of chronic kidney disease, is gradually augmented in parallel to progression to endstage renal disease and is further accelerated by renal replacement therapy. Oxidative stress ensues when there is an imbalance between reactive pro-oxidants and physiologically occurring electron donating antioxidant defence systems. During the last decade, a close association of oxidative stress with accelerated atherosclerosis and increased risk for CV and all-cause mortality has been established. Lipid peroxidation has been identified as a trigger for endothelial dysfunction, the first step towards atherogenesis. In order to counteract the deleterious effects of free radicals and thereby ameliorate, or delay, CV disease, exogenous administration of antioxidants has been proposed. Here, we attempt to summarize existing data from studies that test antioxidants for CV protection, such as vitamins E and C, statins, omega-3 fatty acids and N-acetylcysteine.

Mitochondrial Dysfunction Plays a Relevant Role in Pathophysiology of Peritoneal Membrane Damage Induced by Peritoneal Dialysis

Preservation of the peritoneal membrane is an essential determinant of the long-term outcome of peritoneal dialysis (PD). Epithelial-to-mesenchymal transition (EMT) plays a central role in the pathogenesis of PD-related peritoneal membrane injury. We hypothesized that mitochondria may be implicated in the mechanisms that initiate and sustain peritoneal membrane damage in this setting. Hence, we carried out ex vivo studies of effluent-derived human mesothelial cells, which disclosed a significant increase in mitochondrial reactive oxygen species (mtROS) production and a loss of mitochondrial membrane potential in mesothelial cells with a fibroblast phenotype, compared to those preserving an epithelial morphology. In addition, in vitro studies of omentum-derived mesothelial cells identified mtROS as mediators of the EMT process as mitoTEMPO, a selective mtROS scavenger, reduced fibronectin protein expression induced by TGF-ß1. Moreover, we quantified mitochondrial DNA (mtDNA) levels in the supernatant of effluent PD solutions, disclosing a direct correlation with small solute transport characteristics (as estimated from the ratio dialysate/plasma of creatinine at 240 min), and an inverse correlation with peritoneal ultrafiltration. These results suggest that mitochondria are involved in the EMT that human peritoneal mesothelial cells suffer in the course of PD therapy. The level of mtDNA in the effluent dialysate of PD patients could perform as a biomarker of PD-induced damage to the peritoneal membrane.

Leukocyte Activation and Antioxidative Defense Are Interrelated and Moderately Modified by n-3 Polyunsaturated Fatty Acid-Enriched Eggs Consumption-Double-Blind Controlled Randomized Clinical Study

This placebo-controlled, double-blind, randomized, interventional study investigated the effects of low/intermediate doses of n-3 polyunsaturated fatty acids (PUFAs) on the endothelial function, markers of leukocyte activation, and oxidative status following dietary intake of n-3 PUFA-enriched hen eggs in young healthy individuals. Twenty young healthy adults of both sexes who consumed n-3 PUFA-enriched hen eggs (two eggs per day, for three weeks, total of approximately 407 mg/day n-3 PUFAs) or regular eggs (two eggs per day for three weeks, total of approximately 75 mg/day n-3 PUFAs) participated in this study. Skin microvascular endothelium-independent and endothelium-dependent vasodilation were assessed by laser Doppler flowmetry. Serum lipid profile and content of free fatty acids, markers of leukocyte activation, biochemical parameters of oxidative stress, as well as antioxidative enzymes serum activity were measured before and after respective dietary protocol. The results of this study revealed significant differences in the markers of leukocyte activation (such as CD11a/LFA-1) and antioxidative defense, which are related to increased intake of n-3 PUFAs, providing the evidence that consumption of nutritionally enriched hen eggs may affect physiological processes related to oxidative balance. The absence of significant changes in microvascular reactivity following supplementation with a low-intermediate dose of n-3 PUFAs, unlike in our previous studies where functional eggs contained ~1 g of n-3 PUFA, suggests the existence of a dose-dependent effect.

Unfavorable Effects of Peritoneal Dialysis Solutions on the Peritoneal Membrane: The Role of Oxidative Stress

One of the main limitations to successful long-term use of peritoneal dialysis (PD) as a renal replacement therapy is the harmful effects of PD solutions to the structure and function of the peritoneal membrane (PM). In PD, the PM serves as a semipermeable membrane that, due to exposure to PD solutions, undergoes structural alterations, including peritoneal fibrosis, vasculopathy, and neoangiogenesis. In recent decades, oxidative stress (OS) has emerged as a novel risk factor for mortality and cardiovascular disease in PD patients. Moreover, it has become evident that OS plays a pivotal role in the pathogenesis and development of the chronic, progressive injury of the PM. In this review, we aimed to present several aspects of OS in PD patients, including the pathophysiologic effects on the PM, clinical implications, and possible therapeutic antioxidant strategies that might protect the integrity of PM during PD therapy.

Agents that Modulate Peritoneal Membrane Structure and Function

Extensive experience with chronic peritoneal dialysis has identified a series of functional and anatomical pathologic changes in the peritoneal membrane thought to be the result of repeated insults from bioincompatible solutions. Laboratory and clinical findings from recent investigations often conflict and are difficult to interpret due to variations in methodologies, animal models, study designs, and data analyses. The principal pathophysiologic mechanisms identified thus far are oxidative stress, inflammation, and their consequences. Many substances used to neutralize the action of these insults, prevent formation of toxic compounds, or directly alter solute and water transport to improve peritoneal membrane performance have been studied. We herein review the most promising of these substances or those that deserve attention because their use has contributed to better understanding of peritoneal pathophysiology. Most peritoneal solution additives have proved useless due to their toxicity and undesirable effects, ineffectiveness, or manufacturing limitations. A few substances deserve more attention, particularly those capable of restoring negatively charged membrane sites, those that somehow improve permselectivity, scavengers of oxidants, and advanced glycation end-product inhibitors and breakers. Recent publications on clinical experience with neutral pH, low glucose degradation product (GDP) peritoneal solutions, although few and preliminary, are most encouraging. The virtual elimination of GDPs in these novel solutions will probably preclude the need for GDP scavengers and inhibitors. Nonetheless, there is room for further significant improvement in solution biocompatibility and for compounds that may restore peritoneal function.

Is oxidative stress an issue in peritoneal dialysis?

During the last two decades, oxidative stress (OS) has emerged as a novel risk factor for a variety of adverse events, including atherosclerosis and mortality in chronic kidney disease (CKD) patients. Increased OS occurs even in early stages of the disease, progresses with deterioration of renal function and is further aggravated by hemodialysis (HD), due to the bioincompatibility of the method. Compared to HD, peritoneal dialysis (PD) is a more biocompatible dialysis modality, characterized by a significantly reduced, but still high, OS status. The culprit for OS in PD is mainly the composition of PD solutions (low pH, lactate buffer, increased osmolarity and high glucose concentration). After heat sterilization of PD solutions, formation of glucose degradation products (GDPs) and advanced glycation end-products (AGEs) trigger inflammation and enhance OS. Chronic exposure of the peritoneum to this toxic, hyperglycemic environment leads to OS-derived morphologic damage of peritoneal cells, loss of ultrafiltration capacity and decreased technique survival. Moreover, OS is linked with peritonitis, loss of residual renal function, inflammation, atherosclerosis, cardiovascular (CV) disease, and increased mortality. To ameliorate OS status in PD, a multitargeted approach is necessary that includes use of neutral pH, low GDP, low lactate and iso-ismolar PD solutions, strict glycemic control, optimal volume management and, probably supplementation with antioxidants, N-acetylcysteine being the most promising among them.

Oxidative Stress in Patients Undergoing Peritoneal Dialysis: A Current Review of the Literature

Peritoneal dialysis (PD) patients manifest excessive oxidative stress (OS) compared to the general population and predialysis chronic kidney disease patients, mainly due to the composition of the PD solution (high-glucose content, low pH, elevated osmolality, increased lactate concentration and glucose degradation products). However, PD could be considered a more biocompatible form of dialysis compared to hemodialysis (HD), since several studies showed that the latter results in an excess accumulation of oxidative products and loss of antioxidants. OS in PD is tightly linked with chronic inflammation, atherogenesis, peritoneal fibrosis, and loss of residual renal function. Although exogenous supplementation of antioxidants, such as vitamins E and C, N-acetylcysteine, and carotenoids, in some cases showed potential beneficial effects in PD patients, relevant recommendations have not been yet adopted in everyday clinical practice.

Antidiabetic andantioxidant properties, and α-amylase and α-glucosidase inhibition effects of triterpene saponins from Piper auritum

Bioactivity-guided fractionation of methanol extracts from leaves of Piper auritum produced four triterpenoid saponin compounds 1-4. Structures were established based on interpretation of mass spectrometry (MS), nuclear magnetic resonance (NMR) data. 21-(p-methoxycinnamoyl)-olean-12-ene-28oic cid-3-O-α-L-arabinopyranosyl-(1→2)-β-D-glucopyranoside (1) and olean-12-ene-28 methyl ester-3-O-α-L-arabinofuranosyl-(1→2)-β-D-glucopyranoside (2) were orally administered to diabetic mice at dosage of 10 mg/kg of body weight per day for 30 days and resultant biochemical parameters were studied. Both compounds significantly (p<0.05) decreased serum glucose, total cholesterol, and triglyceride levels, compared with controls. Low density lipoprotein and high density lipoprotein cholesterol levels were ameliorated. The effects of lipid peroxidation and oxidative stress in the liver, pancreas, and kidney were reversed, with reductions insulin resistance and stimulation of insulin production. β-Glucosidase activities were studied in vitro. Compounds 1 and 2 can be used to improve glucose and lipid metabolism and to reduce the imbalance between generation of reactive oxygen species and scavenging enzyme activities for prevention of diabetic complications.

Effects of dialysis solution on the cardiovascular function in peritoneal dialysis patients

Objective Peritoneal dialysis (PD) patients have an increased cardiovascular burden. In this study, we aimed to compare certain PD solutions (Physioneal(®) and Dianeal(®)) in terms of the ambulatory blood pressure, echocardiographic parameters (ECHO), carotid atherosclerosis, endothelial function and serum asymmetric dimethylarginine (ADMA) level. Methods A total of 45 PD patients were enrolled in this prospective randomized controlled study: 23 patients in the Dianeal(®) group and 22 patients in the Physioneal(®) group. Ambulatory blood pressure measurements, echocardiography, carotid artery intima-media thickness measurements and flow mediated dilatation (FMD) and ADMA values were obtained at baseline and 12 months. Results The baseline parameters were similar between the groups with respect to the echocardiographic parameters, 24-hour ambulatory blood monitoring measurements and ADMA and FMD levels. All 24-hour blood pressure monitoring measurements, except for the average daytime systolic blood pressure, were significantly decreased in both groups at the first year. In the Physioneal(®) group, a significant decrease was observed with regard to the ADMA levels. Considering the FMD values, significant augmentation was seen at the end of the first year in both groups. Improvements in the FMD measurements were prominent in the Physioneal(®) group; however, this finding was not statistically significant. Conclusion The use of solutions with a neutral pH in PD patients results in decreased ADMA levels, which may be an important contributor to reductions in the incidence of cardiovascular events and deaths in this population.

The therapeutic effects of MSc1 nanocomplex, synthesized by nanochelating technology, on experimental autoimmune encephalomyelitic C57/BL6 mice

Purpose

Currently approved therapies for multiple sclerosis (MS) at best only slow down its progression. Therefore, it is necessary to utilize novel technologies in order to synthesize smart multifunctional structures. In the present study, for the first time we evaluated the therapeutic potential of MSc1 nanocomplex, which was designed based on novel nanochelating technology.

Materials and methods

MSc1 cell-protection capacity, with and without iron bond, was evaluated against hydrogen peroxide (H₂O₂)-induced oxidative stress in cultured rat pheochromocytoma-12 cells. The ability of MSc1 to maintain iron bond at pH ranges of 1–7 was evaluated. Nanocomplex toxicity was examined by estimating the intraperitoneal median lethal dose (LD₅₀). Experimental autoimmune encephalomyelitic mice were injected with MSc1 14 days after disease induction, when the clinical symptoms appeared. The clinical score, body weight, and disease-induced mortality were monitored until day 54. In the end, after collecting blood samples for assessing hemoglobin and red blood cell count, the brains and livers of the mice were isolated for hematoxylin and eosin staining and analysis of iron content, respectively.

Results

The results showed that MSc1 prevented H₂O₂-induced cell death even after binding with iron, and it preserved its bond with iron constant at pH ranges 1–7. The nanocomplex intraperitoneal LD₅₀ was 1,776.59 mg/kg. MSc1 prompted therapeutic behavior and improved the disabling features of experimental autoimmune encephalomyelitis, which was confirmed by decreased clinical scores versus increased body mass and 100% survival probability. It did not cause any adverse effects on hemoglobin or red blood cell count. Histopathological studies showed no neural loss or lymphocyte infiltration in MSc1-treated mice, while the hepatic iron content was also normal.

Conclusion

These results demonstrate that MSc1 could be a promising beneficial novel agent and has the capacity to be evaluated in further studies.

Effects of elevated dietary iron on the gastrointestinal expression of Nramp genes and iron homeostasis in rainbow trout (Oncorhynchus mykiss)

Diet is the primary source of iron (Fe) for freshwater fish, and the absorption of Fe is believed to occur via the Nramp family of divalent metal transporters (also called DMT1). Presently, the homeostatic regulation of dietary Fe absorption in fish is poorly understood. This study examined the gastrointestinal mRNA expression of two Nramp isoforms, Nramp-β and Nramp-γ, in the freshwater rainbow trout (Oncorhynchus mykiss), following exposure to elevated dietary Fe [1,256 mg Fe/kg food vs. 136 mg Fe/kg food (control)] for 14 days. The physiological performance, plasma Fe status and tissue-specific accumulation of Fe were also evaluated. In general, the mRNA expression level of Nramp was higher in the intestine relative to the stomach. Interestingly, fish fed on a high-Fe diet exhibited a significant induction in Nramp expression after 7 days, followed by a decrease to the level observed in control fish on day 14. The increase in Nramp expression correlated with the elevated gastrointestinal and plasma Fe concentrations. However, the hepatic Fe concentration remained unchanged during the entire exposure period, indicating strong homeostatic regulation of hepatic Fe level in fish. Fish appeared to handle increased systemic Fe level by elevating the plasma transferrin level, thereby enhancing the Fe-binding capacity in the plasma. Overall, our study provides new interesting insights into the homeostatic regulation of dietary Fe uptake and handling in freshwater fish.

Assessment of the Antioxidant and Reactive Oxygen Species Scavenging Activity of Methanolic Extract of Caesalpinia crista Leaf

"Oxidative stress" is initiated by reactive oxygen species (ROS), which are responsible for majority of the diseases. However, antioxidants with ROS scavenging ability may have great relevance in the prevention of oxidative stress. The present study was undertaken, using a 70% methanolic extract of Caesalpinia crista leaves, to examine different in vitro tests in diversified fields including total antioxidant activity, scavenging activities for various ROS, iron chelating activity and phenolic and flavonoid contents. Total antioxidant activity was evaluated as trolox equivalent antioxidant capacity value of 0.546 ± 0.014. The extract was investigated for different ROS scavenging activities and IC(50) values were found to be 0.44 ± 0.1 mg/ml, 24.9 ± 0.98 μg/ml, 33.72 ± 0.85 μg/ml, 61.13 ± 3.24 μg/mL and 170.51 ± 4.68 μg/mL for hydroxyl, superoxide, nitric oxide, singlet oxygen and hypochlorous acid, respectively; however, no significant results were obtained in scavenging of hydrogen peroxide and peroxynitrite anion. The extract was found to be a potent iron chelator with IC(50) = 279.85 ± 4.72 μg/mL. The plant extract (100 mg) yielded 50.23 ± 0.003 mg/mL gallic acid equivalent phenolic content and 106.83 ± 0.0003 mg/mL quercetin equivalent flavonoid content. In the in vivo experiments, the extract treatment showed significant increase in the level of superoxide dismutase, catalase, glutathione-S-transferase and reduced glutathione. In a word, it may be concluded that 70% methanol extract of C. crista leaves acts as an antioxidant and ROS scavenger; which may be due to the presence of phenolic and flavonoid compounds.

Intracellular free calcium concentration and calcium transport in human erythrocytes of lead-exposed workers

Erythrocytes are the route of lead distribution to organs and tissues. The effect of lead on calcium homeostasis in human erythrocytes and other excitable cells is not known. In the present work we studied the effect of lead intoxication on the uptake and efflux (measured as (Ca(2+)-Mg(2+))-ATPase activity) of calcium were studied in erythrocytes obtained from lead-exposed workers. Blood samples were taken from 15 workers exposed to lead (blood lead concentration 74.4+/-21.9 microg/dl) and 15 non-exposed workers (9.9+/-2 microg/dl). In erythrocytes of lead-exposed workers, the intracellular free calcium was 79+/-13 nM, a significantly higher concentration (ANOVA, P<0.01) than the one detected in control (30+/-9 nM). The enhanced intracellular free calcium was associated with a higher osmotic fragility and with important modifications in erythrocytes shape. The high intracellular free calcium in lead-exposed workers was also related to a 100% increase in calcium incorporation and to 50% reduction of (Ca(2+)-Mg(2+))-ATPase activity. Lipid peroxidation was 1.7-fold higher in erythrocytes of lead-exposed workers as compared with control. The alteration on calcium equilibrium in erythrocytes is discussed in light of the toxicological effects in lead-exposed workers.

Transferrin inhibits stress-induced apoptosis in a beetle

Transferrin in insects is known as an iron transporter, an antibiotic agent, a vitellogenin, and a juvenile hormone-regulated protein. We show here a novel functional role for insect transferrin. Stresses, such as iron overload, bacterial or fungal challenge, cold or heat shock, wounding, and H2O2 or paraquat exposure, cause upregulation of the beetle Apriona germari transferrin (AgTf) gene in the fat body and epidermis, and they cause increased AgTf protein levels. RNA interference (RNAi)-mediated AgTf reduction results in rapid induction of apoptotic cell death in the fat body during exposure to heat stress. The observed effect of AgTf RNAi indicates that AgTf inhibits heat stress-induced apoptotic cell death, suggesting a functional role for AgTf in defense and stress responses in the beetle.