Reactive oxygen species participate in peroxynitrite-induced apoptosis in HL-60 cells

Effects of chronic hydrogen peroxide exposure on mitochondrial oxidative stress genes, ROS production and lipid peroxidation in HL60 cells

Hydrogen peroxide (H2O2) is a reactive species that is also involved in the redox regulation of cells because of it is relative stability. In numerous pathological situations, a chronic increase in the production of reactive species is observed, which is related to oxidative stress and cellular damage. This study aimed to evaluate the effects of long-term exposure to different H2O2 concentrations on oxidative stress biomarkers and mitochondrial dynamics in HL60 cells. HL60 cells were treated with a sustained production (0.1, 1.0 and 10.0 nM/s) of H2O2 for one hour. H2O2 production and malondialdehyde (MDA) levels, as a lipid peroxidation marker, increased progressively in HL60 cells in accordance with higher H2O2 exposure, with significant differences between the 10 nM/s H2O2 group and the control and 0.1 nM/s groups. Similarly, progressive increased expression in genes related to the mitochondrial antioxidant defences and mitochondrial dynamics were also observed. Significantly increased gene expression in the 10 nM/s H2O2 with respect to the control group was observed for manganese superoxide dismutase (MnSOD), peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PCG1α), nuclear respiratory factor 2 (Nrf2), mitochondrial transcription factor A (Tfam), mitofusins 1 and 2 (Mfn1 and Mfn2) and uncoupling protein 3 (UCP3), whereas no significant changes were observed in the cytochrome c oxidase subunit IV (COXIV) gene expression. In conclusion, exposure to different sustained production of H2O2 is related to a progressive increase in the gene expression of mitochondrial dynamics and redox processes in HL60 cells, but also to oxidative damage at higher H2O2 production levels.

The Role of the Vascular System in Degenerative Diseases: Mechanisms and Implications

Degenerative diseases, encompassing a wide range of conditions affecting various organ systems, pose significant challenges to global healthcare systems. This comprehensive review explores the intricate interplay between the vascular system and degenerative diseases, shedding light on the underlying mechanisms and profound implications for disease progression and management. The pivotal role of the vascular system in maintaining tissue homeostasis is highlighted, as it serves as the conduit for oxygen, nutrients, and immune cells to vital organs and tissues. Due to the vital role of the vascular system in maintaining homeostasis, its dysfunction, characterized by impaired blood flow, endothelial dysfunction, and vascular inflammation, emerges as a common denominator of degenerative diseases across multiple systems. In the nervous system, we explored the influence of vascular factors on neurodegenerative diseases such as Alzheimer's and Parkinson's, emphasizing the critical role of cerebral blood flow regulation and the blood-brain barrier. Within the kidney system, the intricate relationship between vascular health and chronic kidney disease is scrutinized, unraveling the mechanisms by which hypertension and other vascular factors contribute to renal dysfunction. Throughout this review, we emphasize the clinical significance of understanding vascular involvement in degenerative diseases and potential therapeutic interventions targeting vascular health, highlighting emerging treatments and prevention strategies. In conclusion, a profound appreciation of the role of the vascular system in degenerative diseases is essential for advancing our understanding of degenerative disease pathogenesis and developing innovative approaches for prevention and treatment. This review provides a comprehensive foundation for researchers, clinicians, and policymakers seeking to address the intricate relationship between vascular health and degenerative diseases in pursuit of improved patient outcomes and enhanced public health.

Role of Nanoparticle-Conjugates and Nanotheranostics in Abrogating Oxidative Stress and Ameliorating Neuroinflammation

Oxidative stress is a deteriorating condition that arises due to an imbalance between the reactive oxygen species and the antioxidant system or defense of the body. The key reasons for the development of such conditions are malfunctioning of various cell organelles, such as mitochondria, endoplasmic reticulum, and Golgi complex, as well as physical and mental disturbances. The nervous system has a relatively high utilization of oxygen, thus making it particularly vulnerable to oxidative stress, which eventually leads to neuronal atrophy and death. This advances the development of neuroinflammation and neurodegeneration-associated disorders such as Alzheimer's disease, Parkinson's disease, epilepsy, dementia, and other memory disorders. It is imperative to treat such conditions as early as possible before they worsen and progress to irreversible damage. Oxidative damage can be negated by two mechanisms: improving the cellular defense system or providing exogenous antioxidants. Natural antioxidants can normally handle such oxidative stress, but they have limited efficacy. The valuable features of nanoparticles and/or nanomaterials, in combination with antioxidant features, offer innovative nanotheranostic tools as potential therapeutic modalities. Hence, this review aims to represent novel therapeutic approaches like utilizing nanoparticles with antioxidant properties and nanotheranostics as delivery systems for potential therapeutic applications in various neuroinflammation- and neurodegeneration-associated disease conditions.

Antitumour Effects of Selected Pyridinium Salts on Sensitive Leukaemia HL60 Cells and Their Multidrug Resistant Topoisomerase II-Defective HL60/MX2 Counterparts

Multidrug resistance (MDR), having a multifactorial nature, is one of the major clinical problems causing the failure of anticancer therapy. The aim of this study was to examine the antitumour effects of selected pyridinium salts, 1-methyl-3-nitropyridine chloride (MNP) and 3,3,6,6,10-pentamethyl-3,4,6,7-tetrahydro-[1,8(2H,5H)-dion]acridine chloride (MDION), on sensitive leukaemia HL60 cells and resistant topoisomerase II-defective HL60/MX2 cells. Cell growth was determined by the MTT test. Intracellular ROS level was measured with the aid of 2′,7′-DCF-DA. The cell cycle distribution was investigated by performing PI staining. DSB formation was examined using the γ-H2AX histone phosphorylation assay. The activity of caspase-3 and caspase-8 was measured with the use of the FLICA test. The assays for examining the lysosome membrane permeabilization were carried out with the aid of LysoTracker Green DND-26. Both studied compounds exerted very similar cytotoxic activities towards sensitive HL60 cells and their MDR counterparts. They modulated the cellular ROS level in a dose-dependent and time-dependent manner and significantly increased the percentage of sensitive HL60 and resistant HL60/MX2 cells with sub-diploid DNA (sub-G1 fraction). However, the induction of DSB formation was not a significant mechanism of action of these pyridinium salts in studied cells. Both examined compounds triggered caspase-3/caspase-8-dependent apoptosis of sensitive HL60 cells and their MDR counterparts. Additionally, the findings of the study indicate that lysosomes may also participate in the programmed death of HL60 as well as HL60/MX2 cells induced by MDION. The data obtained in this work showed that both examined pyridinium salts, MNP and MDION, are able to retain high antileukaemic effects against multidrug resistant topoisomerase II-defective HL60/MX2 cells.

The Interplay between cGMP and Calcium Signaling in Alzheimer’s Disease

Cyclic guanosine monophosphate (cGMP) is a ubiquitous second messenger and a key molecule in many important signaling cascades in the body and brain, including phototransduction, olfaction, vasodilation, and functional hyperemia. Additionally, cGMP is involved in long-term potentiation (LTP), a cellular correlate of learning and memory, and recent studies have identified the cGMP-increasing drug Sildenafil as a potential risk modifier in Alzheimer’s disease (AD). AD development is accompanied by a net increase in the expression of nitric oxide (NO) synthases but a decreased activity of soluble guanylate cyclases, so the exact sign and extent of AD-mediated imbalance remain unclear. Moreover, human patients and mouse models of the disease present with entangled deregulation of both cGMP and Ca²⁺ signaling, e.g., causing changes in cGMP-mediated Ca²⁺ release from the intracellular stores as well as Ca²⁺-mediated cGMP production. Still, the mechanisms governing such interplay are poorly understood. Here, we review the recent data on mechanisms underlying the brain cGMP signaling and its interconnection with Ca²⁺ signaling. We also discuss the recent evidence stressing the importance of such interplay for normal brain function as well as in Alzheimer’s disease.

ROS systems are a new integrated network for sensing homeostasis and alarming stresses in organelle metabolic processes

Reactive oxygen species (ROS) are critical for the progression of cardiovascular diseases, inflammations and tumors. However, the mechanisms of how ROS sense metabolic stress, regulate metabolic pathways and initiate proliferation, inflammation and cell death responses remain poorly characterized. In this analytic review, we concluded that: 1) Based on different features and functions, eleven types of ROS can be classified into seven functional groups: metabolic stress-sensing, chemical connecting, organelle communication, stress branch-out, inflammasome-activating, dual functions and triple functions ROS. 2) Among the ROS generation systems, mitochondria consume the most amount of oxygen; and nine types of ROS are generated; thus, mitochondrial ROS systems serve as the central hub for connecting ROS with inflammasome activation, trained immunity and immunometabolic pathways. 3) Increased nuclear ROS production significantly promotes cell death in comparison to that in other organelles. Nuclear ROS systems serve as a convergent hub and decision-makers to connect unbearable and alarming metabolic stresses to inflammation and cell death. 4) Balanced ROS levels indicate physiological homeostasis of various metabolic processes in subcellular organelles and cytosol, while imbalanced ROS levels present alarms for pathological organelle stresses in metabolic processes. Based on these analyses, we propose a working model that ROS systems are a new integrated network for sensing homeostasis and alarming stress in metabolic processes in various subcellular organelles. Our model provides novel insights on the roles of the ROS systems in bridging metabolic stress to inflammation, cell death and tumorigenesis; and provide novel therapeutic targets for treating those diseases. (Word count: 246).

Quercetin Triggers Induction of Apoptotic and Lysosomal Death of Sensitive and Multidrug Resistant Leukaemia HL60 Cells

Multidrug resistance (MDR) constitutes the major cause of the failure in anticancer therapy. One of the most important mechanisms leading to the occurrence of MDR is related to the modulation of cellular death pathways. The aim of this study was to determine the effect of quercetin (Q) on triggering the programed death of human promyelocytic leukemia sensitive cells HL60 as well as multidrug resistant HL60/VINC cells overexpressing P-glycoprotein and HL60/MX2 cells characterized by the presence of mutated α isoform of topoisomerase II and the absence of β isoform of this enzyme. Q exerted comparable cytotoxic activities toward sensitive HL60 cells and their MDR counterparts. It was also found that this compound modulated the cellular level of reactive oxygen species (ROS) and led to the marked decrease in cellular GSH level. Furthermore, it was demonstrated that Q used at IC₅₀ and IC₉₀ significantly increased the percentage of sub-G1 subpopulation of all studied leukemia cells causing oligonucleosomal DNA fragmentation. The present study also indicated that Q used at IC₉₀ triggers predominantly programed cell death of sensitive HL60 cells and their MDR counterparts by induction of apoptosis occurring with the involvement of caspase-3 and caspase-8 as well as by lysosome membrane permeabilization-dependent mechanisms.

Prognostic Value of Oxidative Stress Markers in Patients with Pulmonary Arterial or Chronic Thromboembolic Pulmonary Hypertension

Oxidative stress is regarded to play a crucial role in the pathophysiology of pulmonary arterial hypertension (PAH) and inoperable chronic thromboembolic pulmonary hypertension (CTEPH). This study evaluated the prognostic value of serum oxidative stress markers (malondialdehyde (MDA), total antioxidant capacity (TAC), catalase activity (CAT), and superoxide activity (SOD)) in patients with PAH and CTEPH (n = 45). During 13 months of follow-up (median 9 months), clinical deterioration occurred in 14 patients (including 2 deaths). On the Cox regression analysis, MDA, TAC, and CAT were associated with clinical deterioration (p = 0.0068, HR = 1.42, 95% CI: 1.10-1.82; p = 0.0038, HR = 0.033, 95% CI: 0.0032-0.33; and p = 0.046, HR = 0.20, 95% CI: 0.04-0.98, respectively). There was no significant difference in SOD (p = 0.53, HR = 0.97, 95% CI: 0.87-1.08). The cut-off value derived from ROC curve analysis was 3.79 μM (p = 0.0048, AUC = 0.76, 95% CI: 0.62-0.91) for MDA, 0.49 mM (p = 0.027, AUC = 0.71, 95% CI: 0.18-0.47) for TAC, and 1.34 U/L (p = 0.029, AUC = 0.71, 95% CI: 0.55-0.86) for CAT. MDA in the group with deterioration was higher (p = 0.0041), while TAC as well as CAT were lower (p = 0.027 and p = 0.028, respectively) when compared to stable patients. Survival without clinical deterioration was significantly longer in patients with lower MDA (p = 0.037, HR = 0.37, 95% CI: 0.12-1.14, log-rank), higher TAC (p = 0.0018, HR = 0.19, 95% CI: 0.06-0.60, log-rank), and higher CAT (p = 0.044, HR = 0.31 95% CI: 0.11-0.88, log-rank). Markers of oxidative stress such as MDA, TAC, and CAT were associated with adverse clinical outcomes in patients with PAH and inoperable or residual CTEPH.

Neuroprotective effects of N-acetylcysteine via inhibition of matrix metalloproteinase in a mouse model of transient global cerebral ischemia

N-acetylcysteine (NAC) is known to serve many biological functions including acting as an antioxidant, and electing antiinflammatory effects. Previous reports have revealed that NAC may have neuroprotective effects against the deleterious effects of brain ischemia. Despite of this, the mechanism by which NAC prevents neuronal damage after brain ischemia remains unclear. The current study aimed to investigate this mechanism in a mouse model of transient global brain ischemia. In the present study, mice were subjected to 20 min of transient global brain ischemia, proceeded by intraperitoneal administration of NAC (150 mg/kg) in one group. The mice were then euthanized 72 h after this ischemic insult for collection of experimental tissues. The effect of NAC on neuronal damage and matrix metalloproteinase (MMP)-9 activity were assessed and immunofluorescence, and hippocampal terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling (TUNEL) assay experiments were conducted and results compared between NAC- and vehicle-treated groups. Neuronal damage was primarily observed in the hippocampal CA1 and CA2 regions. In NAC-treated mice, neuronal damage was significantly reduced after ischemia when compared to vehicle-treated animals. NAC also inhibited increased MMP-9 activity after global brain ischemia. NAC increased laminin and NeuN expression and inhibited increases in TUNEL-positive cells, all in the hippocampus. These results suggest that NAC reduces hippocampal neuronal damage following transient global ischemia, potentially via reductions in MMP-9 activity.

Antitumour effects of selected plant polyphenols, gallic acid and ellagic acid, on sensitive and multidrug-resistant leukaemia HL60 cells

The aim of this study was to examine the antitumour effects of plant phenolic acids, gallic acid (GA) and ellagic acid (EA), on human promyelocytic leukaemia sensitive HL60 cell line and its resistant sublines exhibiting two MDR phenotypes: HL60/VINC (overexpressing P-glycoprotein) and HL60/MX2 (characterized by the presence of mutated α isoform of topoisomerase II). Both studied compounds exerted comparable cytotoxic activities towards sensitive HL60 cells and their MDR counterparts. It was also found that GA and EA modulated the cellular level of reactive oxygen species in a dose-dependent and time-dependent manner. Furthermore, it was demonstrated that GA (IC₉₀ ) and EA (IC₅₀ and IC₉₀ ) significantly increased the percentage of sub-G1 subpopulation of all studied leukaemia cells causing oligonucleosomal DNA fragmentation. Both compounds used at IC₉₀ triggered mainly the apoptotic death of these cells. However, GA had no effect on the activity of caspase-3 as well as caspase-8 in sensitive HL60 cells and their MDR counterparts. In contrast, EA provoked a significant activation of these caspases in all studied leukaemia cells. It was also found that lysosomes were not involved in triggering programmed death of sensitive HL60 and MDR cells by GA and EA.

Carnosic Acid, a Natural Diterpene, Attenuates Arsenic-Induced Hepatotoxicity via Reducing Oxidative Stress, MAPK Activation, and Apoptotic Cell Death Pathway

The present studies have been executed to explore the protective mechanism of carnosic acid (CA) against NaAsO₂-induced hepatic injury. CA exhibited a concentration dependent (1–4 μM) increase in cell viability against NaAsO₂ (12 μM) in murine hepatocytes. NaAsO₂ treatment significantly enhanced the ROS-mediated oxidative stress in the hepatic cells both in in vitro and in vivo systems. Significant activation of MAPK, NF-κB, p53, and intrinsic and extrinsic apoptotic signaling was observed in NaAsO₂-exposed hepatic cells. CA could significantly counteract with redox stress and ROS-mediated signaling and thereby attenuated NaAsO₂-mediated hepatotoxicity. NaAsO₂ (10 mg/kg) treatment caused significant increment in the As bioaccumulation, cytosolic ATP level, DNA fragmentation, and oxidation in the liver of experimental mice (n = 6). The serum biochemical and haematological parameters were significantly altered in the NaAsO₂-exposed mice (n = 6). Simultaneous treatment with CA (10 and 20 mg/kg) could significantly reinstate the NaAsO₂-mediated toxicological effects in the liver. Molecular docking and dynamics predicted the possible interaction patterns and the stability of interactions between CA and signal proteins. ADME prediction anticipated the drug-likeness characteristics of CA. Hence, there would be an option to employ CA as a new therapeutic agent against As-mediated toxic manifestations in future.

Protocatechuic Acid, a Phenolic from Sansevieria roxburghiana Leaves, Suppresses Diabetic Cardiomyopathy via Stimulating Glucose Metabolism, Ameliorating Oxidative Stress, and Inhibiting Inflammation

Persistent hyperglycemia, impairment of redox status and establishment of inflammatory pathophysiology integrally play important role in the pathogenesis of diabetic cardiomyopathy (DC). Present study examined the therapeutic potential of protocatechuic acid isolated from the Sansevieria roxburghiana rhizomes against DC employing rodent model of type 2 diabetes (T2D). T2D was induced by high fat diet + a low-single dose of streptozotocin (35 mg/kg, i.p.). T2D rats exhibited significantly (p < 0.01) high fasting blood glucose level. Alteration in serum lipid profile (p < 0.01) and increased levels of lactate dehydrogenase (p < 0.01) and creatine kinase (p < 0.01) in the sera of T2D rats revealed the occurrence of hyperlipidemia and diabetic pathophysiology. A significantly (p < 0.01) high levels of serum C-reactive protein and pro-inflammatory mediators revealed the establishment of inflammatory occurrence in T2D rats. Besides, significantly high levels of troponins in the sera revealed the establishment of cardiac dysfunctions in T2D rats. However, protocatechuic acid (50 and 100 mg/kg, p.o.) treatment could significantly reverse the changes in serum biochemical parameters related to cardiac dysfunctions. Molecular mechanism studies demonstrated impairment of signaling cascade, IRS1/PI3K/Akt/AMPK/p 38/GLUT4, in glucose metabolism in the skeletal muscle of T2D rats. Significant (p < 0.01) activation of polyol pathway, enhanced production of AGEs, oxidative stress and up-regulation of inflammatory signaling cascades (PKC/NF-κB/PARP) were observed in the myocardial tissue of T2D rats. However, protocatechuic acid (50 and 100 mg/kg, p.o.) treatment could significantly (p < 0.05–0.01) stimulate glucose metabolism in skeletal muscle, regulated glycemic and lipid status, reduced the secretion of pro-inflammatory cytokines, and restored the myocardial physiology in T2D rats near to normalcy. Histological assessments were also in agreement with the above findings. In silico molecular docking study again supported the interactions of protocatechuic acid with different signaling molecules, PI3K, IRS, Akt, AMPK PKC, NF-κB and PARP, involved in glucose utilization and inflammatory pathophysiology. In silico ADME study predicted that protocatechuic acid would support the drug-likeness character. Combining all, results would suggest a possibility of protocatechuic acid to be a new therapeutic agent for DC in future.

Sansevieria roxburghiana Schult. & Schult. F. (Family: Asparagaceae) Attenuates Type 2 Diabetes and Its Associated Cardiomyopathy

BACKGROUND

Sansevieria roxburghiana Schult. & Schult. F. (Family: Asparagaceae) rhizome has been claimed to possess antidiabetic activity in the ethno-medicinal literature in India. Therefore, present experiments were carried out to explore the protective role of edible (aqueous) extract of S. roxburghiana rhizome (SR) against experimentally induced type 2 diabetes mellitus (T2DM) and its associated cardiomyopathy in Wistar rats.

METHODS

SR was chemically characterized by GC-MS analysis. Antidiabetic activity of SR (50 and 100 mg/kg, orally) was measured in high fat diets (ad libitum) + low-single dose of streptozotocin (35 mg/kg, intraperitoneal) induced type 2 diabetic (T2D) rat. Fasting blood glucose level was measured at specific intermissions. Serum biochemical and inflammatory markers were estimated after sacrificing the animals. Besides, myocardial redox status, expressions of signal proteins (NF-κB and PKCs), histological and ultrastructural studies of heart were performed in the controls and SR treated T2D rats.

RESULTS

Phytochemical screening of the crude extract revealed the presence of phenolic compounds, sugar alcohols, sterols, amino acids, saturated fatty acids within SR. T2D rats exhibited significantly (p < 0.01) higher fasting blood glucose level with respect to control. Alteration in serum lipid profile (p < 0.01) and increased levels of lactate dehydrogenase (p < 0.01) and creatine kinase (p < 0.01) in the sera revealed the occurrence of hyperlipidemia and cell destruction in T2D rats. T2DM caused significant (p < 0.05-0.01) alteration in the biochemical markers in the sera. T2DM altered the redox status (p < 0.05-0.01), decreased (p < 0.01) the intracellular NAD and ATP concentrations in the myocardial tissues of experimental rats. While investigating the molecular mechanism, activation PKC isoforms was observed in the selected tissues. T2D rats also exhibited an up-regulation in nuclear NF-κB (p65) in the cardiac tissues. So, oral administration of SR (50 and 500 mg/kg) could reduce hyperglycemia, hyperlipidemia, membrane disintegration, oxidative stress, vascular inflammation and prevented the activation of oxidative stress induced signaling cascades leading to cell death. Histological and ultra-structural studies of cardiac tissues supported the protective characteristics of SR.

CONCLUSIONS

From the present findings it can be concluded that, SR could offer protection against T2DM and its associated cardio-toxicity via multiple mechanisms viz. hypoglycemic, antioxidant and anti-inflammatory actions.

Cytoprotective and Antioxidant Effects of an Edible Herb, Enhydra fluctuans Lour. (Asteraceae), against Experimentally Induced Lead Acetate Intoxication

Background

Enhydra fluctuans Lour. (Asteraceae), an edible aquatic herb, is traditionally employed against toxic effects of heavy metals in India. The present study was planned to discover the protective effect of edible extract of E. fluctuans (AEEF) against Pb toxicity.

Methods

The cytoprotective role of AEEF was determined on murine hepatocytes employing MTT assay and Hoechst staining. The effects on lipid peroxidation, protein carbonylation, endogenous redox systems and the transcription levels of apoptotic proteins were studied after incubating the hepatocytes with AEEF (400 μg/ml) + Pb-acetate (6.8 μM). The defensive role of AEEF (100 mg/kg) against Pb-acetate (5 mg/kg) intoxication was measured in mice by in vivo assays. Biochemical, haematological and histological parameters, intracellular Pb burden and redox status were measured.

Results

AEEF exhibited a concentration dependent cytoprotective effect against Pb-induced cytotoxicity in vitro. Pb-acetate incubation significantly (p < 0.01) altered the extents of ROS production ↑, protein carbonylation ↑, lipid peroxidation ↑, endogenous antioxidant enzymes ↓ and GSH ↓ in vitro. Besides, Pb-acetate significantly (p < 0.01) induced apoptosis in the hepatocytes apparent from the altered expressions of apoptotic proteins viz. Apaf-1 ↑, Bad ↑, Bcl-2 ↓, Cyt C ↑, cleaved caspases↑, Bid ↑ and Fas ↑. However, AEEF (400 μg/ml) could significantly (p < 0.05–0.01) attenuate the Pb-acetate mediated toxic manifestation in vitro. In in vivo assay, Pb-acetate (5 mg/kg) treated mice exhibited significantly (p < 0.01) high intracellular Pb content. A high Pb-burden within the tissues caused significant (p < 0.05–0.01) patho-physiological alterations viz. ROS production ↑, protein carbonylation↑, lipid peroxidation ↑, DNA fragmentation ↑, ATP formation ↑, mitochondrial co-enzymes Q ↓, endogenous antioxidant enzymes ↓ and GSH ↓ within the selected tissues. The haematological and serum biochemical parameters were significantly (p < 0.05–0.01) different in the Pb-acetate treated mice. Finally, histological assessment imposed significant toxic occurrence within the organs of Pb-intoxicated animals. However, concurrent administration of AEEF (100 mg/kg) could significantly (p < 0.05–0.01) reinstate the Pb-acetate mediated toxicity.

Conclusion

Presence of metal chelators and phyto-antioxidants within AEEF would offer overall protection through promoting Pb clearance coupled with restoring redox balance.

Oxidative Stress and Inflammation in Hepatic Diseases: Therapeutic Possibilities of N-Acetylcysteine

Liver disease is highly prevalent in the world. Oxidative stress (OS) and inflammation are the most important pathogenetic events in liver diseases, regardless the different etiology and natural course. N-acetyl-l-cysteine (the active form) (NAC) is being studied in diseases characterized by increased OS or decreased glutathione (GSH) level. NAC acts mainly on the supply of cysteine for GSH synthesis. The objective of this review is to examine experimental and clinical studies that evaluate the antioxidant and anti-inflammatory roles of NAC in attenuating markers of inflammation and OS in hepatic damage. The results related to the supplementation of NAC in any form of administration and type of study are satisfactory in 85.5% (n = 59) of the cases evaluated (n = 69, 100%). Within this percentage, the dosage of NAC utilized in studies in vivo varied from 0.204 up to 2 g/kg/day. A standard experimental design of protection and treatment as well as the choice of the route of administration, with a broader evaluation of OS and inflammation markers in the serum or other biological matrixes, in animal models, are necessary. Clinical studies are urgently required, to have a clear view, so that, the professionals can be sure about the effectiveness and safety of NAC prescription.

Regulation of apoptosis through bcl-2/bax proteins expression and DNA damage by Zanthoxylum alatum

CONTEXT

Many of the major chemotherapeutic agents are secondary metabolites found in nature. Zanthoxylum alatum Roxb. (Rutaceae) is traditionally used in the treatment of various diseases.

OBJECTIVE

The present study evaluates the apoptotic activity of methanol extract of Z. alatum (MEZA) on Ehrlich ascites tumor (EAT) in Swiss albino mice.

MATERIALS AND METHODS

The presence of flavonoids in MEZA was standardized by HPLC. The in vitro cytotoxicity of MEZA was measured by the MTT assay. The in vivo antitumor activity of MEZA (100 and 200 mg/kg b.w., i.p. for 9 days) was also evaluated. On the 10th day, EAT tumor volume, cell viability, and hematological parameters were assayed. Apoptotic morphology was determined by acredine orange/ethedium bromide using fluorescence microscopy. Apoptosis percentage was measured by flow cytometric analysis using annexine-V-FITC. Also, DNA damage and bcl-2/bax were estimated by UV-method and western blot, respectively.

RESULTS AND DISCUSSION

HPLC analysis revealed presence of three flavonoids, rutin, myricetin, and quercetin. MEZA showed satisfactory cytotoxicity in MTT assay (IC50 = 111.50 µg/ml). The extract significantly (p < 0.01) changed the tumor volume, viable, non-viable cell count, and hematological parameters towards the normal. Apoptotic activity of MEZA was confirmed by acridine orange/ethidium bromide staining, annexin-V-FITC staining, DNA fragmentation, and Bcl-2/Bax ratio.

CONCLUSION

The study showed that MEZA has antitumor activity which may be due to the presence of flavonoids in the extract.

Protective effect of arjunolic acid against atorvastatin induced hepatic and renal pathophysiology via MAPK, mitochondria and ER dependent pathways

3-Hydroxy-3-methylglutaryl-CoA reductase inhibitor, atorvastatin (ATO), is a highly effective drug used for the treatment of hypercholesterolemia and hypertriglyceridemia. Its application is restricted now-a-days due to several acute and chronic side effects. ATO induced anti hypercholesterolemia and hepatic tissue toxicity has been reported to follow different mechanisms. The present study has been carried out to investigate the protective role of arjunolic acid (AA) against ATO induced oxidative impairment and cell death in hepatic and renal tissue in mice. Administration of ATO (at a dose 30 mg/kg/day for 8 weeks) enhanced serum markers, increased reactive oxygen species (ROS) production and altered the pro oxidant-antioxidant status of liver and kidney tissues. Our experimental evidence suggests that ATO exposure induces apoptotic cell deathby the activation of caspase-3 and reciprocal regulation of Bcl-2/Bax with the concomitant reduction of mitochondrial membrane potential and increased level of cytosolic cytochrome c, Apaf1, caspase-9. Besides, ATO markedly increased the phosphorylation of MAPKs, enhanced caspase-12 and calpain level. Histological studies and DNA fragmentation analysis also support the toxic effect of ATO in these organs pathophysiology. Post treatment with AA (at a dose of 20 mg/kg body weight for 4 days), however, reduced ATO-induced oxidative stress and suppressed all these apoptotic events. Results suggest that AA could effectively and extensively counteract these adverse effects and might protect liver and kidney from ATO-induced severe tissue toxicity.

Protective effects of blueberries (Vaccinium corymbosum L.) extract against cadmium-induced hepatotoxicity in mice

The oxidative status and morphological changes of mouse liver exposed to cadmium chloride (Cd(II)) and therapeutic potential of blueberry (Vaccinium corymbosum L.) extract against Cd(II)-induced hepatic injury were investigated. A variety of parameters were evaluated, including lipid peroxidation (LPO), protein carbonyl (PCO) level, DNA fragment, as well as antioxidative defense system (i.e., superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH)). Elemental analysis and evaluation of morphological changes and NO levels were also performed. Exposure to Cd(II) led to increased LPO and PCO as well as DNA fragment and a reduction of SOD and CAT activities, however, the content of GSH elevated probably due to biological adaptive-response. In contrast, co-treatment of anthocyanin (Ay) inhibited the increased oxidative parameters as well as restored the activities of antioxidative defense system in a dose-dependent manner. Ay administration regained these morphological changes caused by intoxication of Cd(II) to nearly normal levels. Moreover, the accumulation of Cd(II) in liver may be one of the reasons for Cd(II) toxicity and Ay can chelate with Cd(II) to reduce Cd(II) burden. The influence of Cd(II) on the Zn and Ca levels can also be adjusted by the co-administration of Ay. Exposure to Cd(II) led to an increase of NO and Ay reduced NO contents probably by directly scavenging. Potential mechanisms for the protective effect of Ay have been proposed, including its anti-oxidative and anti-inflammatory effect along with the metal-chelating capacity. These results suggest that blueberry extract may be valuable as a therapeutic agent in combating Cd(II)-induced tissue injury.

Therapeutic potential of different commercially available synbiotic on acetaminophen-induced uremic rats

BACKGROUND

Currently kidney disease appears a foremost problem across the world. Acetaminophen is a commonly used antipyretic agent, which in high doses, causes uremia and used for experimentally induction of kidney disease. Bacteriotherapy affords a promising approach to mitigate uremic toxins by ingestion of urease positive bacteria, probiotics and symbiotic able to catabolize uremic solutes within the gut. The present study evaluates the effect of seven commercial symbiotic on kidney disease.

METHODS

Fifty-four albino male rats were randomly divided into nine groups. Control group (Group-I) received distilled water interperitoneally for 7 days. Positive control group (Group-II) received 500 mg/kg acetaminophen interperitoneally for 7 days. Commercially available seven symbiotic combinations at a dose of 10(9)cells/day for 3 weeks was administered to the tested groups (Group III-IX) after receiving 500 mg/kg/day acetaminophen interperitoneally for 7 days. Blood, kidney, liver and stool samples were collected after scarification for biochemical tests and DNA fragmentation assay of kidney tissue, kidney histological studies. Limited fecal analysis was conducted.

RESULT

Blood urea nitrogen and toxicity indicators were increased, and antioxidant enzymes were decreased in Group-II. Blood urea nitrogen, toxicity indicators, glomerular necrosis, DNA damage of kidney tissue were reduced, and antioxidant enzymes were increased significantly in the treated Groups IV and IX (p < 0.05) in response to Group-II. Number of pathogenic bacteria decreased in synbiotic treated groups than Group I and II.

CONCLUSION

The study demonstrated that some of commercial symbiotic combination can reduce the sever effect of kidney disease.

In vitro effect of cadmium and copper on separated blood leukocytes of Dicentrarchus labrax

The immunotoxic effects of heavy metals on blood leukocytes of sea bass (Dicentrarchus labrax) were examined. The cells, separated by a discontinuous Percoll-gradients, were exposed in vitro to various sublethal concentrations of cadmium and copper (10(-7)M, 10(-5)M, and 10(-3)M) and their immunotoxic effect was then evaluated by measuring neutral red uptake, MTT assay, DNA fragmentation and Hsp70 gene expression. First of all, we demonstrated that the cells treated in vitro could incorporate Cd and Cu. A relationship between heavy metal exposure and dose-time-dependent alterations in responses of leukocytes from blood was found for both metals, but copper was more immunotoxic than cadmium in all assays performed. A significant reduction in the cells׳ ability to uptake neutral red and viability by MTT assay was recorded, indicating that both cadmium and copper could change the membrane permeability, inducing cellular apoptosis when the concentration of metals reached 10(-3)M. The apoptotic effect may also explain the high level of cytotoxicity found when the leukocytes were exposed to higher concentration of metals. These results demonstrated that toxic effect of copper and cadmium affect on the mechanisms of cell-mediated immunity reducing the immune defences of the organism.

Early weaning PCB 95 exposure alters the neonatal endocrine system: thyroid adipokine dysfunction

Polychlorinated biphenyls (PCBs) are persistent environmental pollutants that can severely disrupt the endocrine system. In the present study, early-weaned male rats were administered a single dose of 2,3,6-2',5'-pentachlorinated biphenyl (PCB 95; 32 mg/kg per day, by i.p. injection) for two consecutive days (postnatal days (PNDs) 15 and 16) and killed 24 and 48 h after the administration of the last dose. Compared with the control group, administration of PCB 95 induced a reduction (P<0.01) in serum concentrations of thyroxine, triiodothyronine, and GH and an increase (P<0.01) in the serum concentration of TSH at PNDs 17 and 18. These conspicuous perturbations led to some histopathological deterioration in the thyroid gland characterized by follicular degeneration, edema, fibrosis, hemorrhage, luminal obliteration, and hypertrophy with reduced colloidal contents at PND 18. The dyshormonogenesis and thyroid dysgenesis may be attributed to the elevation of DNA fragmentation at PNDs 17 and 18. Furthermore, this hypothyroid state revealed higher (P<0.01) serum concentrations of leptin, adiponectin, and tumor necrosis factor and lower (P<0.01) serum concentrations of IGF1 and insulin at both PNDs compared with the control group. Interestingly, the body weight of the neonates in the PCB 95 group exhibited severe decreases throughout the experimental period in relation to that of the control group. These results imply that PCB 95 may act as a disruptor of the developmental hypothalamic-pituitary-thyroid axis. Hypothyroidism caused by PCB 95 may impair the adipokine axis, fat metabolism, and in general postnatal development. Thus, further studies need to be carried out to understand this concept.

Effect of ascorbic acid and X-irradiation on HL-60 human leukemia cells: the kinetics of reactive oxygen species

Ascorbic acid (AsA) treatment is expected to be a potential cancer therapy strategy with few side-effects that can be used alone or in combination with chemotherapy. However, the combination of AsA, a free radical scavenger, with radiation is not clearly understood; conflicting data are reported for cancer cell death. We conducted this study to determine the effect of AsA treatment combined with X-irradiation and the role of reactive oxygen species (ROS) in HL-60 human promyelocytic leukemia cells. Additive cytotoxic effects were observed when the cells were exposed to 2 Gy X-irradiation after 2.5 mM AsA treatment. When catalase was added to the culture with AsA alone, the cytotoxic effects of AsA disappeared. X-irradiation increased intercellular ROS levels and mitochondrial superoxide levels. By contrast, AsA alone and in combination with X-irradiation decreased ROS levels. However, in the presence of catalase neutralizing H2O2, AsA alone or in combination with X-irradiation only slightly decreased the intercellular ROS. Moreover, AsA decreased the mitochondrial membrane potential, which is commonly associated with apoptosis. These results suggest that the reduction of ROS did not result from ROS scavenging by AsA, and AsA induced apoptosis through a ROS-independent pathway. This study reports that a combination of AsA with radiation treatment is effective in cancer therapy when considering ROS in cancer cells.

Cadmium induced pathophysiology: prophylactic role of edible jute (Corchorus olitorius) leaves with special emphasis on oxidative stress and mitochondrial involvement

The present study was undertaken to evaluate the protective effect of aqueous extract of Corchorus olitorius leaves (AECO) against CdCl₂ intoxication. In vitro bioassay on isolated mice hepatocytes confirmed dose dependent cytoprotective effect of AECO. The CdCl₂ (30 μM) exhibited a significantly increased levels of lipid peroxidation, protein carbonylation along with the reduction of antioxidant enzymes and reduced glutathione levels in hepatocytes. AECO (200 and 400 μg/ml) + CdCl₂ (30 μM) could significantly restore the aforementioned oxidation parameters in hepatocytes. Beside this, AECO could significantly reduce Cd-induced increase in Bad/Bcl-2 ratio and the over-expression of NF-κB, caspase 3 and caspase 9. In in vivo assay, CdCl₂ (4 mg/kg body weight, for 6 days) treated rats exhibited a significantly increased intracellular Cd accumulation, oxidative stress and DNA fragmentation in the organs. In addition, the haematological parameters were significantly altered in the CdCl₂ treated rats. Simultaneous administration of AECO (50 and 100 mg/kg body weight), could significantly restore the biochemical, antioxidant and haematological parameters near to the normal status. Histological studies of the organs supported the protective role of jute leaves. Presence of substantial quantity of phenolic compounds and flavonoids in extract may be responsible for overall protective effect.

The chemistry and biological activities of N-acetylcysteine

BACKGROUND

N-acetylcysteine (NAC) has been in clinical practice for several decades. It has been used as a mucolytic agent and for the treatment of numerous disorders including paracetamol intoxication, doxorubicin cardiotoxicity, ischemia-reperfusion cardiac injury, acute respiratory distress syndrome, bronchitis, chemotherapy-induced toxicity, HIV/AIDS, heavy metal toxicity and psychiatric disorders.

SCOPE OF REVIEW

The mechanisms underlying the therapeutic and clinical applications of NAC are complex and still unclear. The present review is focused on the chemistry of NAC and its interactions and functions at the organ, tissue and cellular levels in an attempt to bridge the gap between its recognized biological activities and chemistry.

MAJOR CONCLUSIONS

The antioxidative activity of NAC as of other thiols can be attributed to its fast reactions with OH, NO2, CO3(-) and thiyl radicals as well as to restitution of impaired targets in vital cellular components. NAC reacts relatively slowly with superoxide, hydrogen-peroxide and peroxynitrite, which cast some doubt on the importance of these reactions under physiological conditions. The uniqueness of NAC is most probably due to efficient reduction of disulfide bonds in proteins thus altering their structures and disrupting their ligand bonding, competition with larger reducing molecules in sterically less accessible spaces, and serving as a precursor of cysteine for GSH synthesis.

GENERAL SIGNIFICANCE

The outlined reactions only partially explain the diverse biological effects of NAC, and further studies are required for determining its ability to cross the cell membrane and the blood-brain barrier as well as elucidating its reactions with components of cell signaling pathways.

Sodium arsenite-induced cardiotoxicity in rats: protective role of p-coumaric acid, a common dietary polyphenol

This study was performed to investigate the ameliorative role of p-coumaric acid against sodium arsenite-induced cardiotoxicity in rats. Sodium arsenite (5 mg/kg/b.wt) was orally administered once a day for 30 days to the animals to induce cardiotoxicity. After the experimental period, cardiotoxicity was assessed by estimating the levels of lipid peroxidation, anti-oxidant status (superoxide dismutase, catalase, glutathione peroxidase, glutathione S-transferase, glutathione reductase, total reduced glutathione, protein sulfyhydryl and non-protein sulfhydryl groups) and DNA fragmentation in the cardiac tissue of control and experimental rats. In addition, cardiac tissue specific serum markers (triacylglycerides, total cholesterol, low-density lipoprotein cholesterol and high density lipoprotein cholesterol) in serum and histopathological changes in the cardiac tissue were also evaluated. From the results obtained in our study, sodium arsenite administration to the rats increased lipid peroxidation, DNA fragmentation, triacylglycerides, total cholesterol and low-density lipoprotein cholesterol, whereas antioxidant status and high-density lipoprotein cholesterol were found to be reduced. However, p-coumaric acid (75 and100 mg/kg/b.wt) treatment orally once per day for 30 days, immediately before a daily administration of sodium arsenite protected the abnormal biochemical abnormalities observed in the cardiac tissue of sodium arsenite treated rats as evidenced by the cardiac histopathology. For comparison purpose, a standard antioxidant vitamin C (100 mg/kg/b.wt) was used. In conclusion, this study concluded that p-coumaric acid could be a promising candidate for protecting the sodium arsenite-induced cardiotoxicity in rats through its antioxidant character.

Toxic effects of lead exposure in Wistar rats: involvement of oxidative stress and the beneficial role of edible jute (Corchorus olitorius) leaves

Lead (Pb) is considered to be a multi-target toxicant. The present study was undertaken to evaluate the protective effect of aqueous extract of Corchorus olitorius leaves against Pb-acetate induced toxic manifestation in blood, liver, kidney, brain and heart of Wistar rats. The Pb-acetate (5mg/kg body weight) treated rats exhibited a significant inhibition of co-enzymes Q, antioxidant enzymes and reduced glutathione levels in the tissues. In addition, the extent of lipid peroxidation, DNA fragmentation and haematological parameters were significantly altered in the Pb-acetate treated rats as compared to control. Simultaneous administration of test extract (25, 50 and 100mg/kg body weight), could significantly restore the biochemical and haematological parameters near to the normal status through antioxidant activity and/or by preventing bioaccumulation of Pb within the tissues of experimental rats. Presence of substantial quantity of phenolics and flavonoids in the extract may be responsible for the observed protective role against Pb-intoxication.

Nitric oxide-mediated apoptosis in rat macrophages subjected to Shiga toxin 2 from Escherichia coli

Shiga toxin-producing Escherichia coli are important food-borne pathogens. The main factor conferring virulence on this bacterium is its capacity to secrete Shiga toxins (Stxs), which have been reported to induce apoptosis in several cell types. However, the mechanisms of this apoptosis have not yet been fully elucidated. In addition, Stxs have been shown to stimulate macrophages to produce nitric oxide (NO), a well-known apoptosis inductor.The aim of this study was to investigate the participation of NO in apoptosis of rat peritoneal macrophages induced by culture supernatants or Stx2 from E. coli. Peritoneal macrophages incubated in the presence of E. coli supernatants showed an increase in the amounts of apoptosis and NO production. Furthermore, inhibition of NO synthesis induced by addition of aminoguanidine (AG) was correlated with a reduction in the percentage of apoptotic cells, indicating participation of this metabolite in the apoptotic process. Similarly, treatment of cells with Stx2 induced an increase in NO production and amount of apoptosis, these changes being reversed by addition of AG. In summary, these data show that treatment with E. coli supernatants or Stx2 induces NO-mediated apoptosis of macrophages.

Effects of verbascoside, biotechnologically purified by Syringa vulgaris plant cell cultures, in a rodent model of periodontitis

Objectives

Verbascoside has previously been characterized as an effective scavenger of active free radicals and an inhibitor of lipid peroxidation. In the present study, we have investigated the effects of verbascoside from Syringa vulgaris in a rat model of ligature-induced periodontitis.

Methods

Male Sprague–Dawley rats were lightly anaesthetized with pentobarbitone (35 mg/kg). Sterile, 2-0 black braided silk thread was placed around the cervix of the lower left first molar and knotted medially. Animals received vebascoside 2 mg/kg orally, daily for 8 days.

Key findings

On the eighth day after placement of the ligature, we evaluated several markers of inflammation: (i) myeloperoxidase activity, (ii) thiobarbituric acid-reactant substance measurements, (iii) NF-κB expression, (iv) iNOS expression, (v) the nitration of tyrosine residues, (vi) activation of the nuclear enzyme poly(ADP-ribose) polymerase, (vii) Bax and Bcl-2 expression and (viii) a degree of gingivomucosal tissue injury. Oral administration of verbascoside (2 mg/kg daily for 8 days) significantly decreased all of the parameters of inflammation as described above.

Conclusions

These results demonstrate that verbascoside exerts an anti-inflammatory role during experimental periodontitis and is able to ameliorate the tissue damage associated with ligature-induced periodontitis.

Ultraviolet B light-induced nitric oxide/peroxynitrite imbalance in keratinocytes--implications for apoptosis and necrosis

Elevation of nitric oxide (NO*) can either promote or inhibit ultraviolet B light (UVB)-induced apoptosis. In this study, we determined real-time concentration of NO* and peroxynitrite (ONOO(-)) and their role in regulation of membrane integrity and apoptosis. Nanosensors (diameter 300-500 nm) were used for direct in situ simultaneous measurements of NO* and ONOO(-) generated by UVB in cultured keratinocytes and mice epidermis. An exposure of keratinocytes to UVB immediately generated ONOO(-) at maximal concentration of 190 nm followed by NO(*) release with a maximal concentration of 91 nm. The kinetics of UVB-induced NO*/ONOO(-) was in contrast to cNOS agonist stimulated NO*/ONOO(-) from keratinocytes. After stimulating cNOS by calcium ionophore (CaI), NO* release from keratinocytes was followed by ONOO(-) production. The [NO*] to [ONOO(-)] ratio generated by UVB decreased below 0.5 indicating a serious imbalance between cytoprotective NO* and cytotoxic ONOO(-)-a main component of nitroxidative stress. The NO*/ONOO(-) imbalance increased membrane damage and cell apoptosis was partially reversed in the presence of free radical scavenger. The results suggest that UVB-induced and cNOS-produced NO* is rapidly scavenged by photolytically and enzymatically generated superoxide (O(2) (-)) to produce high levels of ONOO(-), which enhances oxidative injury and apoptosis of the irradiated cells.

Taurine protects acetaminophen-induced oxidative damage in mice kidney through APAP urinary excretion and CYP2E1 inactivation

Acute exposure of acetaminophen (APAP), a widely used analgesic and antipyretic drug, causes severe renal damage and no specific agent has been reported so far that plays any beneficial role in this organ pathophysiology. In the present study, the protective role of taurine on APAP-induced nephrotoxicity was investigated in mice. In order to induce acute nephrotoxicity, APAP was administered at a single dose of 2g/kg body weight orally to male adult albino mice of Swiss strain. APAP exposure for 24h significantly increased plasma level of blood urea nitrogen (BUN), creatinine, uric acid, TNF-alpha, NO production, urinary gamma-glutamyl transpeptidase (gamma-GT) activity, total urinary protein and urinary glucose level accompanied by a decrease in Na(+)-K(+)-ATPase activity. Moreover, APAP administration significantly increased MDA, protein carbonylation, GSSG level, intracellular ROS production and cytochrome P450 enzyme (CYPP450) activity. The same exposure decreased GSH level, ferric reducing/antioxidant power (FRAP) as well as the activities of antioxidant enzymes indicating that APAP-induced renal damage was mediated through oxidative stress. Besides, APAP exposure significantly reduced mitochondrial membrane potential and induced up-regulation of CYP2E1 in renal tissues although JNK did not play any significant role in this APAP-induced renal pathophysiology. Caspase 9/3 immunoblot and DNA fragmentation analyses showed that APAP-induced renal cell damage was mostly necrotic in nature, although some apoptosis also occurred simultaneously. Taurine treatment both pre and post (150 mg/kg body weight for 3 days, orally) to APAP exposure, however, significantly reduced APAP-induced nephrotoxicity through its antioxidant properties, urinary excretion of APAP and suppression of CYP2E1. Results suggest that taurine might be a potential therapeutic candidate against APAP-induced acute nephrotoxicity.

Protective effect of Corchorus olitorius leaves on sodium arsenite-induced toxicity in experimental rats

The present study was undertaken to evaluate the protective effect of aqueous extract of Corchorus olitorius leaves (AECO) against sodium arsenite-induced toxicity in experimental rats. The animals exposed to sodium arsenite at a dose of 10mg/kg body weight p.o. for 10days exhibited a significant inhibition (p<0.01) of hepatic and renal antioxidant enzymes namely superoxide dismutase, catalase, glutathione-S-transferase, glutathione peroxidase and glutathione reductase. In addition, arsenic intoxication significantly decreased (p<0.01) the level of reduced glutathione and increased (p<0.01) the levels of oxidized glutathione and thiobarbituric acid reactive substances in selected tissues. Treatment with AECO at doses of 50 and 100mg/kg body weight p.o. for 15days prior to arsenic intoxication significantly improved hepatic and renal antioxidant markers in a dose dependant manner. AECO treatment also significantly reduced the arsenic-induced DNA fragmentation of hepatic and renal tissues. Histological studies on the ultrastructural changes of liver and kidney supported the protective activity of the AECO. The results concluded that the treatment with AECO prior to arsenic intoxication has significant role in protecting animals from arsenic-induced hepatic and renal toxicity.

Taurine plays a beneficial role against cadmium-induced oxidative renal dysfunction

The present study has been carried out to investigate the role of taurine (2-aminoethanesulfonic acid), a conditionally essential amino acid, in ameliorating cadmium-induced renal dysfunctions in mice. Cadmium chloride (CdCl(2)) has been selected as the source of cadmium. Intraperitoneal administration of CdCl(2 )(at a dose of 4 mg/kg body weight for 3 days) caused significant accumulation of cadmium in renal tissues and lessened kidney weight to body weight ratio. Cadmium administration reduced intracellular ferric reducing/antioxidant power (FRAP) of renal tissues. Levels of serum marker enzymes related to renal damage, creatinine and urea nitrogen (UN) have been elevated due to cadmium toxicity. Cadmium exposure diminished the activities of enzymatic antioxidants, superoxide dismutase (SOD), catalase (CAT), glutathione-S-transferase (GST), glutathione reductase (GR), glutathione peroxidase (GPx) and glucose-6-phosphate dehydrogenase (G6PD) as well as non-enzymatic antioxidant, reduced glutathione (GSH) and total thiols. On the other hand, the levels of oxidized glutathione (GSSG), lipid peroxidation, protein carbonylation, DNA fragmentation, concentration of superoxide radicals and activities of cytochrome P450 enzymes (CYP P450s) have been found to increase due to cadmium intoxication. Treatment with taurine (at a dose of 100 mg/kg body weight for 5 days) before cadmium intoxication prevented the toxin-induced oxidative impairments in renal tissues. The beneficial role of taurine against cadmium-induced renal damage was supported from histological examination of renal segments. Vitamin C, a well-established antioxidant was used as the positive control in the study. Experimental evidence suggests that both taurine and vitamin C provide antioxidant defense against cadmium-induced renal oxidative injury. Combining all, results suggest that taurine protects murine kidneys against cadmium-induced oxidative impairments, probably via its antioxidative property.

Cadmium-induced neurological disorders: prophylactic role of taurine

The present study was conducted to investigate whether the conditionally essential amino acid taurine could play any protective role against the potent neurotoxin cadmium (Cd)-induced oxidative impairment in mice brain. Cd administration in the form of CdCl(2 )(at a dose of 4 mg kg(-1) body weight for 3 days, orally) increased the intracellular accumulation of metallic Cd, reactive oxygen species and super oxide radicals. The toxin also augmented the extent of lipid peroxidation, protein carbonylation and the levels of glutathione disulfide. Activities of the antioxidant enzymes and the levels of reduced glutathione as well as total thiols have been significantly decreased due to Cd exposure. In addition, the toxin also caused significant DNA degradation (as evidenced from DNA smearing and diphenylamine reaction). Oral administration of taurine (at a dose of 100 mg kg(-1) body weight for 5 days) was found to be very effective in the prevention of Cd-induced oxidative impairment in the brain tissue of experimental mice. In addition, taurine treatment could also prevent the reduction in the in vivo antioxidant power linearly up to a dose of 100 mg kg(-1) body weight. The preventive role of taurine against Cd-induced cerebral oxidative damage was supported by the observation under scanning electron microscope as well as histological examination of brain segments. To validate the experimental results, a well-known water soluble antioxidant, vitamin C, was used as the positive control in the study. In all, the results suggest that taurine plays a beneficial role against Cd-induced cerebral oxidative stress.

Induction of necrosis in cadmium-induced hepatic oxidative stress and its prevention by the prophylactic properties of taurine

The present study has been carried out to investigate the protective role of taurine against cadmium (Cd)-induced oxidative impairment in murine liver. Oral administration of cadmium chloride (CdCl(2)) at a dose of 4mg/kg body weight for 6 days increased the accumulation of the Cd in the liver and diminished the liver weight to body weight ratio. The CdCl(2) altered the levels of intracellular trace elements, cofactors of various metalloenzymes and increased the activities of serum marker enzymes related to liver dysfunction. In addition, Cd intoxication also attenuated intracellular antioxidant power, the activities of antioxidant enzymes as well as the levels of cellular metabolites. Moreover, level of hepatic metallothionein, lipid peroxidation, protein carbonylation, DNA fragmentation, concentration of intracellular reactive oxygen species (ROS) and the activities of cytochrome P450s have been increased due to Cd toxicity. In addition to the oxidative impairments, Cd exposure caused hepatic cell death mainly via the necrotic pathway. Oral administration of taurine at a dose of 100mg/kg body weight for 5 days prior to CdCl(2) intoxication prevented the alterations of all the toxic-induced hepatic damages. Histological studies also supported the beneficial role of taurine against Cd-induced hepatic damages. Combining all, results suggest that taurine could protect hepatic tissues against Cd-induced oxidative stress probably through its antioxidant activity.

Protection of Arsenic-Induced Hepatic Disorder by Arjunolic Acid

Arsenic is one of the ubiquitous environmental pollutants, which affects nearly all organ systems. The present study has been carried out to investigate the hepatoprotective role of arjunolic acid, a triterpenoid saponin, against arsenic-induced oxidative damages in murine livers. Administration of sodium arsenite at a dose of 10 mg/kg body weight for 2 days significantly reduced the activities of antioxidant enzymes, superoxide dismutase, catalase, glutathione S-transferase, glutathione reductase and glutathione peroxidase as well as depleted the level of reduced glutathione and total thiols. In addition, sodium arsenite also increased the activities of serum marker enzymes, alanine transaminase and alkaline phosphatase, enhanced DNA fragmentation, protein carbonyl content, lipid peroxidation end-products and the level of oxidized glutathione. Studies with arjunolic acid show that in vitro it possesses free radical-scavenging and in vivo antioxidant activities. Treatment with arjunolic acid at a dose of 20 mg/kg body weight for 4 days prior to arsenic administration prevents the alterations of the activities of all antioxidant indices and levels of the other parameters studied. Histological studies revealed less centrilobular necrosis in the liver treated with arjunolic acid prior to arsenic intoxication compared to the liver treated with the toxin alone. Effects of a known antioxidant, vitamin C, have been included in the study as a positive control. In conclusion, the results suggest that arjunolic acid possesses the ability to attenuate arsenic-induced oxidative stress in murine liver probably via its antioxidant activity.

Role of oxygen in postischemic myocardial injury

Myocardial function is dependent on a constant supply of oxygen from the coronary circulation. A reduction of oxygen supply due to coronary obstruction results in myocardial ischemia, which leads to cardiac dysfunction. Reperfusion of the ischemic myocardium is required for tissue survival. Thrombolytic therapy, coronary artery bypass surgery and coronary angioplasty are some of the treatments available for the restoration of blood flow to the ischemic myocardium. However, the restoration of blood flow may also lead to reperfusion injury, resulting in myocyte death. Thus, any imbalance between oxygen supply and metabolic demand leads to functional, metabolic, morphologic, and electrophysiologic alterations, causing cell death. Myocardial ischemia reperfusion (IR) injury is a multifactorial process that is mediated by oxygen free radicals, neutrophil activation and infiltration, calcium overload, and apoptosis. Controlled reperfusion of the ischemic myocardium has been advocated to prevent the IR injury. Studies have shown that reperfusion injury and postischemic cardiac function are related to the quantity and delivery of oxygen during reperfusion. Substantial evidence suggests that controlled reoxygenation may ameliorate postischemic organ dysfunction. In this review, we discuss the role of oxygenation during reperfusion and subsequent biochemical and pathologic alterations in reperfused myocardium and recovery of heart function.

Pro-apoptotic effect of fly ash leachates in hepatocytes of freshwater fish (Channa punctata Bloch)

The pro-apoptotic effect of fly ash leachates (FAL) was studied in the hepatocytes of an Indian freshwater fish, Channa punctata Bloch. Hepatocytes were exposed to different concentrations of '7-day' FAL for 24 and 48h and various parameters of apoptosis were studied using standardized procedures. FAL-induced apoptosis in hepatocytes was indicated by cytological examination, DNA fragmentation and DNA laddering. The induction in cytochrome-c release, caspases 3, 7, 10 and 9 activities and lactate dehydrogenase level provide mechanistic platform for FAL-induced apoptosis. Cytological examination showed an unambiguous apoptotic effect of ash leachates in fish hepatocytes. Exposed hepatocytes also showed increased production of H(2)O(2), superoxide ions and an increase in lipid peroxidation (LPO). The present study suggests a possible role of reactive oxygen species (ROS) in FAL-induced apoptosis in hepatocytes. Lactate dehydrogenase, LPO and apoptosis as biomarkers of cytotoxicity have recently been used for assessment of ecotoxicological impact of environmental chemicals. Our findings show that these biomarkers may also be used for evaluation of ecotoxicological impact of complex chemical mixture such as fly ash and its leachates.

Renal damage in rats induced by myocardial ischemia/reperfusion: Role of nitric oxide

BACKGROUND

It has been demonstrated that myocardial ischemia/reperfusion (MI/R) causes renal damage. However, the mechanism underlying this damage in kidneys during revascularization of myocardium is unclear. Direct renal ischemia/reperfusion has been implicated in the induction of inducible nitric oxide synthase (iNOS) that leads to increase production of nitric oxide (NO). Recently, excessive production of NO has been found to be involved in causing renal injury by formatting peroxinitrite (ONOO(-)). The aim of this study was to investigate whether NO has a role in this damage, using aminoguanidine (AMG), a known iNOS inhibitor and an antioxidant, in rats undergoing MI/R.

METHODS

Male Wistar rats were used for the experiments (n = 7 each group). In the MI/R group, the left coronary artery was occluded for 30 min and then reperfused for 120 min; the same procedure was used for the AMG group, with the additional step of AMG (200 mg/kg) administered 10 min prior to ischemia. A control group underwent sham operation. At the end of the reperfusion period, all rats were killed and their kidneys removed for biochemical determination and histopathological analysis.

RESULTS

Myocardial ischemia/reperfusion in the rat kidney was accompanied by a significant increase in malondialdehyde and NO production, and a decrease in glutathione content. Administration of AMG reduced malondialdehyde and NO production and prevented depletion of glutathione content. These beneficial changes in the biochemical parameters were also associated with parallel changes in histopathological appearance.

CONCLUSION

These findings suggest that MI/R plays a causal role in kidney injury and AMG exerts renal-protective effects, probably by inhibiting NO production and antioxidant activities.

Effect of aminoguanidine on ischemia-reperfusion induced myocardial injury in rats

Myocardial ischemia-reperfusion (MI/R) has been implicated in the induction of inducible nitric oxide synthase (iNOS) that leads to increase production of nitric oxide (NO). Recently, excessive production of NO has been involved in causing myocardial injury. In our in vivo model, we examined the effects of aminoguanidine (AMG), a known iNOS inhibitor, on percentage infarct size in anaesthetized rats. A total of 14 rats were equally divided into two groups (n = 7 in each group). To produce myocardial necrosis, the left main coronary artery was occluded for 30 min, followed by 120 min of reperfusion, in anesthetized rats. AMG (200 mg kg(-1)) was given intravenously 10 min before occlusion. The volume of infarct size and the risk zone were determined by planimentry of each tracing and multiplying by the slice thickness. Infarct size was normalized by expressing it as a percentage of the area at risk. Hemodynamic parameters were measured via the left carotid artery. Compared to MI/R group, whereas AMG administration elevated mean arterial blood pressure, statistically reduced the myocardial infarct size (21+/- 1 and 14+/- 4%, respectively) and infract size/risk zone (53+/- 3 and 37+/- 5%, respectively) in rat model of ischemia-reperfusion. In conclusion, this study indicates that iNOS inhibitor, AMG, show reduction in NO's side effect in I/R injury.