Lead-induced downregulation of soluble guanylate cyclase in isolated rat aortic segments mediated by reactive oxygen species and cyclooxygenase-2

Associations of multiple plasma metals with chronic kidney disease in patients with diabetes

As common contaminants, metals are non-negligible risk factors for diabetes and chronic kidney disease. However, whether there is an association between multiple metals exposure and incident chronic kidney disease (CKD) risk in patients with diabetes is unclear. We conducted a prospective study to evaluate these associations. In total, 3071 diabetics with baseline estimated glomerular filtration rate (eGFR) ≥ 60 mL/min/1.73 m² from the Dongfeng-Tongji cohort were included. We measured baseline plasma concentrations of 23 metals and investigated the associations between plasma metal concentrations and CKD in diabetics using logistic regression, the least absolute shrinkage and selection operator (LASSO), and the Bayesian Kernel Machine Regression (BKMR) models. During average 4.6 years of follow-up, 457 diabetics developed CKD (14.9 %). The three models consistently found plasma levels of zinc, arsenic, and rubidium had a positive association with incident CKD risk in patients with diabetes, while titanium, cadmium, and lead had an inverse correlation. The results of BKMR showed a significant and positive overall effect of 23 metals on the risk of CKD, when all of the metals were above the 50th percentile as compared to the median value. In addition, potential interactions of zinc and arsenic, zinc and cadmium, zinc and lead, titanium and arsenic, and cadmium and lead on CKD risk were observed. In summary, we found significant associations of plasma titanium, zinc, arsenic, rubidium, cadmium, and lead with CKD in diabetes and interactions between these metals except for rubidium. Co-exposure to multiple metals was associated with increased CKD risk in diabetics.

Effect of iron and folate supplementation on Pb levels in pregnant anemic women: a prospective study

There are few reports revealing association between iron intake and environmental lead exposure during pregnancy. Therefore, the present study was undertaken to investigate the effect of iron supplementation on biochemical modulation of certain lead toxicity markers associated with pregnancy. Iron and folic acid supplementations were given to 250 pregnant anemic women (mild = 100, moderate = 100 and severe = 50) and 100 age matched nonanemic pregnant women as controls for 100 days. Lead (Pb) toxicity markers, enzymatic and nonenzymatic antioxidant were estimated as per standard protocols. The levels of Pb, serum transferrin receptors (sTfR), zinc protoporphyrin (ZPP), δ-aminolevulinic acid (δ-ALA, both in blood and urine) were found significantly increased in all pretreated subjects and these were decreased after oral iron supplementation. Iron-deficient pregnant women reflected a significant increase in lipid peroxide levels (LPO) and protein carbonyl levels (PC) which were found to be further increased after iron supplementation. The levels of iron (Fe), haemoglobin (Hb), ferritin, delta aminolevulinic acid dehydratase (δ-ALAD), catalase (CAT), superoxide dismutase (SOD), and reduced glutathione levels (GSH) were significantly decreased in pretreated groups and these parameters were found significantly increased in all supplemented subjects after treatment. Antioxidant vitamins viz. C and E were found significantly decreased in all post treated groups. Our observation suggests that recommended iron dose is not only effective for blood indices parameters, but it also decreases Pb concentrations in the blood during pregnancy. However, further studies with larger sample size are needed to confirm these findings.

Lead (Pb) exposure and heart failure risk

Lead (Pb) is a heavy metal with widespread industrial use, but it is also a widespread environmental contaminant with serious toxicological consequences to many species. Pb exposure adversely impacts the cardiovascular system in humans, leading to cardiac dysfunction, but its effects on heart failure risk remain poorly elucidated. To better understand the pathophysiological effects of Pb, we review potential mechanisms by which Pb exposure leads to cardiac dysfunction. Adverse effects of Pb exposure on cardiac function include heart failure risk, pressure overload, arrhythmia, myocardial ischemia, and cardiotoxicity. The data reviewed clearly establish that Pb exposure can play an important role in the occurrence and development of heart failure. Future epidemiological and mechanistic studies should be developed to better understand the involvement of Pb exposure in heart failure.

Platelet-rich plasma as a potential therapeutic approach against lead nitrate- and/or gamma radiation-induced hepatotoxicity

Because of the potential regenerative and cytoprotective effects of its content of numerous bioactive growth factors and cytokines, platelet-rich plasma (PRP) became an attractive biomaterial for therapeutic purposes. Therefore, the current study was designed to investigate the potential therapeutic effect of PRP against lead nitrate- and/or γ-radiation-induced hepatotoxicity. To do so, hepatotoxicity was induced in rats by intraperitoneal administration of lead nitrate (7.5 mg/kg) thrice weekly for two consecutive weeks and/or a whole-body γ-irradiation at a single dose of 6 Gy. Activated PRP (0.5 ml/kg) was injected subcutaneously 24 h after the last dose of lead nitrate and/or γ-irradiation and continued twice weekly for three successive weeks. Lead nitrate intoxication and/or γ-irradiation resulted in a significant elevation of serum alanine transaminase and aspartate transaminase activities accompanied with a significant decrease in serum levels of total protein and albumin. Further, a significant increase in malondialdehyde level and nitric oxide content accompanied with a significant decrease in the reduced glutathione content and the enzyme activities of glutathione-S-transferase, superoxide dismutase, and catalase were observed. Additionally, hepatic extracellular signal-regulated kinase (ERK) and Akt signaling pathways were stimulated. PRP treatment notably ameliorated the induced cell injury, reduced the intracellular oxidative and interestingly increased the upregulation of phosphorylated ERK1/2 and Akt. Moreover, PRP treatment relieved lead nitrate and/or γ-radiation-induced hepatic histological damages. In conclusion, this study sheds the light on a probable therapeutic role of PRP against lead nitrate- and/or γ-radiation-induced hepatotoxicity which might attribute to its ability to activate ERK and Akt signaling pathways.

Assessing lead toxicity in the clam Ruditapes philippinarum: Bioaccumulation and biochemical responses

Lead (Pb) is a non-essential metal. Its occurrence in the environment is related principally to anthropogenic contamination. Pb is toxic to aquatic organisms and can provoke damage to membranes and inhibit the activity of essential enzymes. The filter-feeding, Manila clam Ruditapes philippinarum is widely used as a biomonitor organism to assess metal toxicity. Among biomarkers related to the Pb toxicity, the enzymatic activity of δ-aminolevulinic acid dehydratase (δ-ALAD) has been adopted as a specific tool. Metallothionein (MT), lipid peroxidation (LPO) and antioxidant enzymes activities, such as catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR) and glutathione S-transferase (GST) and superoxidase dismutase (SOD) have also been employed to assess the toxic effect of metals. Two target tissues, the gills and the digestive gland, were selected to examine biomarker responses. In order to assess the effects of Pb accumulation and the mechanisms involved in the recovery from it, clams were exposed at two Pb levels (10 and 100 µg/L) for 7 days and were later maintained in clean water for 7 days as a depuration period. Pb accumulation was dependent on the exposure concentration and higher Pb levels were observed in the gills compared to the digestive gland. Inhibition of δ-ALAD, GST and SOD and the induction of MT and LPO over the exposure period were observed in the gills and the digestive gland of R. philippinarum. The depuration period showed a continuous inhibition of the δ-ALAD activity and induction of MT and LPO in both tissues. These results demonstrate that lead induced an exposure effect and the 7 days of depuration were not sufficient to recover the basal health status of the clams.

Apocynin Ameliorates Pressure Overload-Induced Cardiac Remodeling by Inhibiting Oxidative Stress and Apoptosis

Oxidative stress plays an important role in pressure overload-induced cardiac remodeling. The purpose of this study was to determine whether apocynin, a nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitor, attenuates pressure overload-induced cardiac remodeling in rats. After abdominal aorta constriction, the surviving rats were randomly divided into four groups: sham group, abdominal aorta constriction group, apocynin group, captopril group. Left ventricular pathological changes were studied using Masson’s trichrome staining. Metalloproteinase-2 (MMP-2) levels in the left ventricle were analyzed by western blot and gelatin zymography. Oxidative stress and apoptotic index were also examined in cardiomyocytes using dihydroethidium and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), respectively. Our results showed that abdominal aorta constriction significantly caused excess collagen deposition and cardiac insult. Treatment with apocynin significantly inhibited deposition of collagen and reduced the level of MMP-2. Furthermore, apocynin also decreased the NADPH oxidase activity, reactive oxygen species production and cardiomyocyte apoptotic index. Interestingly, apocynin only inhibited NADPH oxidase activity without affecting its expression or the level of angiotension II in the left ventricle. In conclusion, apocynin reduced collagen deposition, oxidative stress, and inhibited apoptosis, ultimately ameliorating cardiac remodeling by mechanisms that are independent of the renin-angiotensin system.

Protective role of silymarin and D-penicillamine against lead-induced liver toxicity and oxidative stress

This study was performed to assess hepatotoxicity and alterations in liver antioxidant defence in acute lead (Pb) exposure and the protective effects of silymarin in comparison to D-penicillamine in rats. Forty eight Albino rats were divided in eight groups and received the following treatments in a 10-day experiment – group 1: normal saline as control; group 2: 25-mg/kg Pb acetate, intraperitoneally (IP) for the last 5 days; group 3: 100-mg/kg D-penicillamine, IP for the last 5 days; group 4: 200-mg/kg silymarin, orally for 10 days; and groups 5, 6, 7 and 8: in addition to Pb, they received D-penicillamine, for the last 5 days, silymarin for 10 days, a combination of silymarin for 10 days and D-penicillamine for the last 5 days and silymarin for the last 5 days, respectively. Pb acetate exposure induced significant elevation in serum alkaline phosphatase (ALP), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) enzyme activities in group 2 compared to control group. Significant reductions in serum total protein and albumin in all Pb-exposed groups and in serum glucose in groups 2, 6 and 8 were also observed. Liver tissue superoxide dismutase and glutathione peroxidase were significantly lower in groups 2 and 8 compared to control group. Silymarin pretreatment and D-penicillamine administration in groups 5, 7 and 8 could significantly lower ALP, ALT and AST and improve liver antioxidant enzymes. Thus, acute Pb exposure induced hepatotoxicity with suppression of liver antioxidant defence system and silymarin, as an antioxidant could alleviate this effect.

Low-level lead exposure changes endothelial modulation in rat resistance pulmonary arteries

Lead exposure induces hypertension and endothelial dysfunction. However, the effects on the pulmonary vasculature have not been explored. In this study, rats exposed to lead acetate for seven days (4μg/100g on the 1st day and 0.05μg/100g/day i.m. subsequently) had lead blood level of 3.9±0.7μg/dL and increased right ventricular pressures. There was an increased Pb deposition and superoxide anions production in the pulmonary arteries, associated with reduced vasoconstriction but unchanged endothelium-dependent vasodilatation to acetylcholine (ACh). In both groups, inhibition of the nitric oxide (NO) synthase with L-NAME blocked the response to ACh, while indomethacin (cycloxygenase inhibitor) had no effect. Incubation with nonspecific potassium channel blocker (tetraethylammonium) reduced the ACh-induced vasodilatation only in the Pb group. Apamin (SKCa channel blocker) and 4-aminopyridine (Kv channel blocker), but not iberiotoxin (BKCa channel blocker), also inhibited this response in the Pb group. The vasodilatation to exogenous NO was reduced by Pb, while relaxation to the cGMP analogue was similar between groups. Concordantly, the protein level of soluble guanylate cyclase (sGC) was reduced. In conclusion, short-term and low-level exposure to Pb changes pulmonary haemodynamic and increases oxidative stress. The pulmonary vasculature exhibited increased hyperpolarization by the Kv and SKCa channels, probably as a compensatory mechanism to the decreased responsiveness to NO.

Spatial Evaluation of Heavy Metals Concentrations in the Surface Sediment of Taihu Lake

With regard to the size of China's freshwater lakes, Taihu Lake ranks third and it plays an important role in the supply of drinking water, flood prevention, farming and navigation, as well as in the travelling industry. The problem of environmental pollution has attracted widespread attention in recent years. In order to understand the levels, distribution and sources of heavy metals in sediments of Taihu Lake, random selection was carried out to obtain 59 samples of surface sediment from the entire lake and study the concentrations of Pb, Cd, Cu, Zn, Cr and Ni. Toxic units were also calculated to normalize the toxicities caused by various heavy metals. As a result, Cd and Cu in sediment were considered lower than the effect range low (ERL) at all regions where samples were gathered, while Pb and Ni were categorized into ERL-effect range median (ERM) at over 22% of the regions where samples were obtained. Nevertheless, all average concentrations of the samples were below the level of potential effect. According to the findings of this research, significant spatial heterogeneity existed in the above heavy metals. In conclusion, the distribution areas of heavy metals with higher concentrations were mainly the north bays, namely Zhushan Bay, Meiliang Bay as well as Gonghu Bay. The distribution areas of Cu, Zn, Cr and Ni with higher concentration also included the lake's central region, whereas the uniform distribution areas of those with lower concentrations were the lake's southeast region. In addition, it was most probable that the spatial distribution of heavy metals was determined by river inputs, whereas atmospheric precipitation caused by urban and traffic contamination also exerted considerable effects on the higher concentrations of Pb and Cd. Through evaluating the total amount of toxic units (ΣTU), it was found that higher toxicity existed primarily in the north bays and central region of the lake. If the heavy metals were sorted by the reduction of mean heavy metal toxic units in Taihu Lake in descending order, it would be Pb, Cr, Ni, Cd, Zn and Cu. Generally speaking, these result of analyses are conducive to alleviating the contamination of heavy metals in Taihu Lake.

Evaluation of mesenchymal stem cells in treatment of infertility in male rats

INTRODUCTION

The present study aimed to elucidate the therapeutic effects of mesenchymal stem cells (MSCs) derived from the bone marrow of rats (BM) against toxic effects of lead (Pb) on the male gonads of experimental rats.

METHODS

The experimental animals were exposed to lead in the form of lead nitrate (LN) one quarter of the LD50. The efficacy of MSCs to reduce gonado-totoxicity induced by lead nitrate at 21, 30 and 60 days, was evaluated experimentally in male rats.

RESULTS

The results showed that testosterone levels and semen quality ameliorated following treatment with MSCs. Also, superoxide dismutase, glutathione peroxidase and catalase levels were increased 21, 30 and 60 days post treatment of MSCs. Moreover, a decrease in genomic DNA alteration and percentage of fragmented DNA was recorded after MSCs treatment. Lead nitrate caused degeneration, necrosis, interstitial edema, and reduction in spermatogenic activity in some seminiferous tubules. The LN-induced changes in histopathologic findings of testis were partially reversed by treatment with MSCs. Histological examination of testis showed deformities in morphology of testis in test animals with gross damage within the seminiferous tubules in Lead nitrate group. The LN-induced changes in histopathologic findings of testis were partially reversed by treatment of MSCs.

CONCLUSIONS

It was concluded that lead is a gonadotoxic with a tendency of suppressing semen characteristics and testosterone levels of animals, the presence of MSCs was found to alleviate the toxic effects of lead. We conclude that MSCs derived from the bone marrow of rats can be an effective therapy of LN induced gonado toxicity, thus can contribute to the treatment of infertility.

Modulation of Pb(II) caused aortal constriction by eugenol and carvacrol

Exposure to lead is known to cause vasoconstriction, exact mechanism of which remains to be elucidated. In this study, we investigate contractile responses of rat aortal rings equilibrated with Pb(II) in organ bath system, explore pathways responsible for hypercontraction and examine two ameliorators of lead-induced hypercontraction. At 1 μmol L(-1) Pb(II), aortal rings showed an average increase of 50% in isometric contraction. Incubation of rings, unexposed to Pb(II), with 1 μmol L(-1) sodium nitroprusside (nitric oxide (NO) donor), 100 μmol L(-1) apocynin (reactive oxygen species (ROS) inhibitor), and 100 μmol L(-1) indomethacin (cyclooxygenase inhibitor) lead to decrease in phenylephrine-induced contraction by 31, 27, and 29%, respectively. This decrease of contraction for Pb(II)-exposed rings was 48, 53, and 38%, respectively, indicating that ROS- and NO-dependent components of contractions are significantly elevated in Pb(II)-induced hypercontraction. Cyclooxygenase-dependent contractile component did not show significant elevation. Eugenol and carvacrol are plant-derived phenols known to possess antioxidant activity and hence could act as possible ameliorators of hypercontraction. At saturating concentrations of 100 μmol L(-1), eugenol and carvacrol caused a decrease in contraction by 38 and 42% in unexposed rings and 46 and 50% in Pb(II)-exposed rings. Co-incubation of rings with eugenol/carvacrol and various inhibitors suggests that both these active principles exert their relaxant effect via quenching of ROS and stimulation of NO synthesis. To conclude, Pb(II) is shown to induce hypercontraction of aortal rings through elevation of ROS and depletion of NO. This hypercontraction is effectively mitigated by eugenol and carvacrol.

Protective role of omega-3 polyunsaturated fatty acid against lead acetate-induced toxicity in liver and kidney of female rats

The present study was conducted to investigate the protective role of Omega-3 polyunsaturated fatty acids against lead acetate-induced toxicity in liver and kidney of female rats. Animals were divided into four equal groups; group 1 served as control while groups 2 and 3 were treated orally with Omega-3 fatty acids at doses of 125 and 260 mg/kg body weight, respectively, for 10 days. These groups were also injected with lead acetate (25 mg/kg body weight) during the last 5 days. Group 4 was treated only with lead acetate for 5 days and served as positive control group. Lead acetate increased oxidative stress through an elevation in MDA associated with depletion in antioxidant enzymes activities in the tissues. Moreover, the elevation of serum enzymes activities (ALT, AST, ALP, and LDH) and the levels of urea and creatinine were estimated but total proteins were decreased. Also, lead acetate-treatment induced hyperlipidemia via increasing of lipid profiles associated with decline in HDL-c level. Significant changes of Hb, PCV, RBCs, PLT, and WBCs in group 4 were recorded. The biochemical alterations of lead acetate were confirmed by histopathological changes and DNA damage. The administration of Omega-3 provided significant protection against lead acetate toxicity.

A blunted anxiolytic like effect of curcumin against acute lead induced anxiety in rat: involvement of serotonin

Anxiety is one of the most common mental disorders sharing extreme or pathological anxiety states as the primary disturbance in mood or emotional tone, with increased fear and exaggerated acute stress responses. Medicinal plants are very variable, but some of them are used as a spice such as curcumin (Curcuma longa). Curcumin shows a wide range of pharmacological potentialities, however, little is known about its anxiolytic properties. The aim of our study was to assess the anti-anxiety potential of curcumin extract against experimental lead induced-anxiety in rats. Experiments were carried out on male Wistar rats intoxicated acutely with an intraperitoneal injection of Pb (25mg/kg B.W.) and/or concomitantly with administration of curcumin (30 mg/kg B.W.) for 3 days. Using immunohistochemistry and anxiety assessment tests (dark light box and elevated plus maze), we evaluated, respectively, the expression of serotonin (5HT) in the dorsal raphe nucleus (DRN) and the anxiety state in our animals. Our results showed, for the first time, a noticeable anxiolytic effect of curcumin against lead induced anxiety in rats and this may possibly result from modulation of central neuronal monoaminergic neurotransmission, especially serotonin, which has shown a significant reduction of the immunoreactivity within the DRN.

Lead modulation of macrophages causes multiorgan detrimental health effects

The environmental toxicant lead (Pb) has detrimental effects on a number of organ systems, including the immune system. Pb exposure decreases host immune defenses against numerous microorganisms and cancer. Although Pb effects on humoral and cell-mediated immunity as well as on erythrocyte, neural, and renal pathophysiology have been well documented, there are few reports regarding Pb's impact on innate immunity, which can affect multiorgan processes. This review focuses on Pb modulation of a key innate immune cell, the macrophage. The impact of Pb on macrophages in different organs, on immature versus mature macrophages, and on low versus high Pb concentrations is discussed. Pb decreases phagocytosis and chemotaxis of macrophages and affects nitric oxide production and eicosanoid metabolism in mature macrophages. Pretreatment of macrophages with Pb increases TNF-α secretion after in vitro stimulation with lipopolysaccharide; however, Pb exposure decreases in vivo intracellular pathogen killing. More recent evidence from mouse studies indicates that even low, environmentally relevant, blood concentrations of Pb result in increased phagocytosis of erythrocytes and decreased expression of interferon-gamma-inducible GTPases, p65-GBP, and p47-IRG, which are necessary for intracellular pathogen killing. Taking into account the effects of Pb on macrophages, the review describes posited mechanisms to account for Pb-altered health effects; Pb effects on heme levels may play a key role as well as Pb's preferential induction of helper type-2 T (Th2) cells and M2 macrophages, which is related to oxidative stress. The discussion links old findings with new, thereby adding new insight into the effects of Pb on macrophages and the resultant compromised immunity and health.

Chronic lead exposure increases blood pressure and myocardial contractility in rats

We investigated the cardiovascular effects of lead exposure, emphasising its direct action on myocardial contractility. Male Wistar rats were sorted randomly into two groups: control (Ct) and treatment with 100 ppm of lead (Pb) in the drinking water. Blood pressure (BP) was measured weekly. At the end of the treatment period, the animals were anaesthetised and haemodynamic parameters and contractility of the left ventricular papillary muscles were recorded. Blood and tissue samples were properly stored for further biochemical investigations. Statistical analyses were considered to be significant at p<0.05. The lead concentrations in the blood reached approximately 13 µg/dL, while the bone was the site of the highest deposition of this metal. BP in the Pb-treated group was higher from the first week of lead exposure and remained at the same level over the next four weeks. Haemodynamic evaluations revealed increases in systolic (Ct: 96±3.79 vs. Pb: 116±1.37 mmHg) and diastolic blood pressure (Ct: 60±2.93 vs. Pb: 70±3.38 mmHg), left ventricular systolic pressure (Ct: 104±5.85 vs. Pb: 120±2.51 mmHg) and heart rate (Ct: 307±10 vs. Pb: 348±16 bpm). Lead treatment did not alter the force and time derivatives of the force of left ventricular papillary muscles that were contracting isometrically. However, our results are suggestive of changes in the kinetics of calcium (Ca⁺⁺) in cardiomyocytes increased transarcolemmal Ca⁺⁺ influx, low Ca⁺⁺ uptake by the sarcoplasmic reticulum and high extrusion by the sarcolemma. Altogether, these results show that despite the increased Ca⁺⁺ influx that was induced by lead exposure, the myocytes had regulatory mechanisms that prevented increases in force, as evidenced in vivo by the increased systolic ventricular pressure.

Vardenafil improves penile erection in type 2 diabetes mellitus patients with erectile dysfunction: role of tropomyosin

INTRODUCTION

Evidences have been suggested that phosphodiesterase type 5 (PDE5) inhibition promotes vasculoprotective benefits in patients with cardiovascular diseases.

AIM

The aim of this study is to analyze the systemic effect of PDE5 inhibition in type 2 diabetes mellitus patients with erectile dysfunction (ED) determining changes in the expression levels of plasma proteins.

METHODS

Seventeen patients with controlled type 2 diabetes mellitus and ED were included in the study. Patients received vardenafil hydrochloride 20 mg on demand during 12 weeks. At the beginning and 12 weeks after vardenafil administration, plasma samples were collected and analyzed using proteomics.

MAIN OUTCOME MEASURES

International Index of Erectile Function-Erectile Function Domain (IIEF-EFD) and plasma protein expression before and after vardenafil administration. Nitrate/nitrite release, PDE5, and soluble guanylate cyclase (sGC) expression and cyclic guanosine monophosphate (cGMP) content in cultured bovine aortic endothelial cells (BAECs).

RESULTS

The IIEF-EFD score was markedly improved after 12 weeks of vardenafil administration. Plasma levels of alpha 1-antitrypsin isotypes 4 and 6 and β-tropomyosin were decreased, whereas apolipoprotein AI isoype 5 was increased 12 weeks after vardenafil administration. Only β-tropomyosin plasma levels were inversely correlated with IIEF-EFD score. Tropomyosin has been added to cultured BAECs and after 24 hours reduced the protein expression level of sGC-β1 subunit and decreased the cGMP content. Tropomyosin did not modify PDE5 expression and nitric oxide release in BAECs as compared with control BAECs. Vardenafil (10 μg/mL) did not modify sGC-β1 subunit expression in tropomyosin + vardenafil-incubated BAECs; however, vardenafil significantly reversed the reduction of cGMP content induced by tropomyosin.

CONCLUSION

Vardenafil administration improved erectile functionality in controlled type 2 diabetes mellitus patients with ED, which was associated with reduction of circulating plasma β-tropomyosin levels. Tropomyosin affected by itself the cGMP generating system suggesting a possible new mechanism involved in ED. Vardenafil reversed the reduction effect of cGMP content elicited by tropomyosin in BAECs.

Cytoprotective and antioxidant effects of the edible halophyte Sarcocornia perennis L. (swampfire) against lead-induced toxicity in renal cells

Lead (Pb) exposure is considered as a risk factor responsible for renal impairment in humans. On the other hand, the halophyte Sarcocornia perennis is a fresh vegetable crop suitable for leafy vegetable production. This study was designed to evaluate the in vitro protective activity of S. perennis against lead-induced damages in HEK293 kidney cells. Morphological and biochemical indicators were used to assess cytotoxicity and oxidative damages caused by Pb treatment on the cells. Our results showed that lead induced (1) a decrease in cell viability (MTT), (2) cell distortion and cohesion loss, (3) superoxide anion production and lipid peroxidation. Conversely, addition of S. perennis extract to the lead-containing medium alleviated every above syndrome. Thus, cell survival was increased and the production of reactive oxygen species caused by Pb treatment was inhibited. Taken together, our study revealed that S. perennis has potent cytoprotective effect against Pb-induced toxicity in HEK 293 cell. Such action would proceed through the decrease in ROS levels and resulting oxidative stress, which suggests a potential interest of this halophyte in the treatment of oxidative-stress related diseases.

Erectogenic and Aphrodisiac Effects of Butea frondosa Koenig ex Roxb. in Rats: Involvement of Enzyme Inhibition

Butea frondosa Koenig ex Roxb. (BF) is traditionally used to manage male sexual disorders including erectile dysfunction (ED). Methanol extract of BF (bark) inhibited Rho-kinase 2 (ROCK-II) enzyme activity in vitro with an IC₅₀ of 20.29 ± 1.83 μg/mL. The relaxant effect of methanol extract of BF (MEBF) was studied on phenylephrine precontracted corpus cavernosum smooth muscle (CCSM) isolated from young rats. The effect of MEBF treatment on sexual behaviour of both young (5 month) and aged (24 month) rats was also studied in addition to the influence on smooth muscle, collagen (collagen-I and -III) level in penis, and sperm characteristics of young and aged rats. MEBF relaxed CCSM up to 21.77 ± 2.57% and increased sexual behavior of young and aged rats. This increase in sexual function could be attributed to ROCK-II inhibition and increase in ratio of smooth muscle to collagen level in rat penile tissue. Increased sperm production and decreased defective sperms in young and aged rats corroborate the usefulness of Butea frondosa in male infertility in addition to ED.

Catalase activity and innate immune response of Caenorhabditis elegans against the heavy metal toxin lead

The heavy metal lead-induced oxidative stress on Caenorhabditis elegans was examined at the level of catalase activity and on innate immunity. Stress-induced C. elegans was exposed to Pseudomonas aeruginosa PA14::GFP for monitoring the impact at the physiological level. Role of catalase on the innate-immune responses of C. elegans was examined. PA14::GFP did not colonize lead pretreated C. elegans intestinal cells significantly compared to untreated controls, indicating stress-mediated upregulation of host-immunity. Semiquantitative PCR analyses of lead-exposed and PA14-infected C. elegans mRNA showed significant upregulation of candidate antimicrobial enzyme gene lys-7 after 24 h of exposures. Upregulation of metallothionein(mtl-1) when compared to mtl-2 in response to the lead suggesting active detoxification of metal by mtl-1. Exogenously provided Catalase (0.4-3.2 U) induced significant upregulation of lys-7 compared to controls. lys-7 upregulation during lead exposure was reconfirmed by real-time PCR. Confocal microscopy and fluorescence spectrophotometer analyses indicated that the lead pretreated C. elegans was significantly less colonized by PA14::GFP when compared to controls. Relative expression of ctl-1 and ctl-2 mRNA was measured using real time PCR and found to be regulated during lead exposures. Over all, the upregulation of antimicrobial gene expression appears to be correlated with the level of catalase during stress emphasizing their key roles in defensive mechanism(s). These results provide a link between the stress and related immune responses which can be explored in higher systems.

Protective potential of Black grapes against lead induced oxidative stress in rats

From time immemorial Vitis vinifera (Black grapes) have been used both for medicinal and nourishment purposes. The aim of this study is to investigate the protective effect of Black grapes against lead nitrate induced oxidative stress. Exposure to lead significantly increased malondialdehyde levels with a significant decrease in superoxide dismutase and catalase activities, and the concentration of GSH in the liver and kidneys of rats. Significantly increased levels of AST, ALT, ALP, BUN and serum creatinine and decreased levels of total protein were observed. The administration of lead significantly decreased the body weight and organ weights at the end of the experimental period. Statistically significant decrease in hemoglobin, red blood cell and total leukocyte count was observed. Pretreatment of hydroalcoholic extract of Black grapes to lead exposed rats significantly ameliorated lead-induced oxidative stress in tissues and produced improvement in hematological parameters over lead-exposed rats, indicating the beneficial role of Black grapes to counteract the lead-induced oxidative stress.

Cellular defense mechanisms against lead toxicity in the vascular system

Lead is a toxic heavy metal that can cause a range of health problems. In this context, the vascular system is a particular target of the deleterious effects of lead. Lead exerts its toxicity through substitution of other divalent cations such as calcium and zinc, resulting in disruption of homeostasis. Based on the evidence that lead up-regulates endoplasmic reticulum (ER) chaperone glucose-regulated protein 78 (GRP78) and/or antioxidant proteins such as hemeoxygenase-1, it is believed that the heavy metal is able to induce ER and/or oxidative stress in cells. These events also suggest that the unfolded protein response (UPR) system and the antioxidant defense system Kelch-like ECH-associated protein 1-nuclear factor (NF)-E2-related factor 2 (Keap1-Nrf2) play a critical role in adaptive response to lead. In this review, we summarize recent progress in lead toxicity in terms of cellular defense systems, including stress proteins and transcription factors involved in the vascular system.

The effect of lead acetate on oxidative stress and antioxidant status in rat bronchoalveolar lavage fluid and lung tissue

Despite the wide spread of lead environmental pollution, the effect of this heavy metal on respiratory disease was not shown yet. In respect to increased oxidative stress is an important mechanism in the pathogenesis of respiratory disease, the present study was designed to examine the association between lead toxicity and lung disease via measuring oxidative stress biomarkers in bronchoalveolar lavage fluid (BALF) and lung tissue of rat. For this aim, 32 rats were divided into the following groups of eight animals each: control, three lead tested (received lead acetate in the drinking water for a period of 14 d at concentrations of 250, 500 and 1000 ppm) groups. At the end of the 2 week period, malondialdehyde (MDA), nitric oxide (NO) and reduced glutathione (GSH) contents were measured to assess free radical activity in the BALF and lung tissue. Superoxide dismutase (SOD) was also determined. A significant dose-dependent increase in the BALF supernatant and lung homogenate levels of MDA and NO with decrease GSH level and SOD activity were observed in the lead-treated groups compared with the control group (p < 0.05). Thus, lead acetate may be contributed to respiratory disorders via increased oxidative stress.

Pyruvate kinase activity and δ-aminolevulinic acid dehydratase activity as biomarkers of toxicity in workers exposed to lead

Lead (Pb(2+)) is a heavy metal that has long been used by humans for a wide range of technological purposes, which is the main reason for its current widespread distribution. Pb(2+) is thought to enter erythrocytes through anion exchange and to remain in the cell by binding to thiol groups. Pyruvate kinase (PK) is a thiol-containing enzyme that plays a key role in erythrocyte cellular energy homeostasis. δ-aminolevulinic acid dehydratase (δ-ALAD) is the second enzyme in the heme biosynthetic pathway and plays a role in the pathogenesis of Pb poisoning. Our primary objective was to investigate the effect of Pb(2+) on the activity of the thiolenzymes δ-ALAD and PK and on the concentration of glutathione (GSH), a nonenzymatic antioxidant defense, in erythrocytes from Pb-exposed workers. The study sample comprised 22 male Pb workers and 21 normal volunteers (15 men and 6 women). The Pb-exposed workers were employed in manufacturing and recycling of automotive batteries. Basic red-cell parameters were assayed and total white blood cell counts performed. PK and δ-ALAD activity and blood Pb (BPb) concentrations were determined in all subjects. Pb-exposed individuals had significantly greater BPb levels than controls. Both PK and δ-ALAD activity levels were significantly lower in Pb-exposed individuals than in controls. Pb significantly inhibited PK and δ-ALAD activity in a dose-dependent manner. We found that erythrocyte GSH levels were lower in Pb-exposed individuals than normal volunteers. Pb-exposed individuals had lower values than controls for several red cell parameters (hemoglobin, hematocrit, red blood cell count, mean corpuscular volume). These results suggest that Pb inhibits δ-ALAD and PK activity by interacting with their thiol groups. It is therefore possible that Pb disrupts energy homeostasis and may be linked with decreased glucose metabolism because it affects the heme synthesis pathway in erythrocytes, contributing to the cell dysfunction observed in these in Pb-exposed individuals. These results indicate an apparent dose-effect relationship between PK activity and BPb. PK activity in human erythrocytes can be used for biological monitoring of Pb exposure. Study of the mechanisms by which Pb acts may contribute to greater understanding of the symptoms caused by Pb.

Cultivation of unculturable soil bacteria

Despite the abundance of bacterial species in soil, more than 99% of these species cannot be cultured by traditional techniques. In addition, the less than 1% of bacteria that can be cultured are not representative of the total phylogenetic diversity. Hence, identifying novel species and their new functions is still an important task for all microbiologists. Cultivating techniques have played an important role in identifying new species but are still low-throughput processes. This review discusses the issues surrounding cultivation, including achievements, limitations, challenges, and future directions.

Evaluation of Low Blood Lead Levels and Its Association with Oxidative Stress in Pregnant Anemic Women: A Comparative Prospective Study

To correlate blood lead levels (BLLs) and oxidative stress parameters in pregnant anemic women. A total of 175 pregnant women were found suitable and included for this study. Following WHO criteria, 50 each were identified as non-anemic, mild anemic and moderate anemic and 25 were severe anemic. The age of all study subjects ranged from 24-41 years. At admission, BLLs and oxidative stress parameters were estimated as per standard protocols and subjected with ANOVA, Pearson correlation analysis and cluster analysis. Results showed significantly (p < 0.01) high BLLs, zinc protoporphyrin (ZPP), oxidized glutathione (GSSG), lipid peroxide (LPO) levels while low delta aminolevulinic acid dehydratase (δ-ALAD), iron (Fe), selenium (Se), zinc (Zn), haemoglobin (Hb), haematocrit (Hct), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC), red blood cell (RBC) count, reduced glutathione (GSH), superoxide dismutase (SOD), catalase (CAT) and total antioxidant capacity (TAC) in all groups of anemic pregnant women as compared with non anemic pregnant women. In all groups of pregnant women, BLLs showed significant (p < 0.01) and direct association with ZPP, GSSG and LPO while inverse relation with δ-ALAD, Fe, Se, Zn, Hb, Hct, MCV, MCH, MCHC, RBC, GSH, SOD, CAT and TAC. Study concluded that low BLLs perturb oxidant-antioxidant balance and negatively affected hematological parameters which may eventually Pb to Fe deficiency anemia during pregnancy.

Blood lead level modifies the association between dietary antioxidants and oxidative stress in an urban adult population

Oxidative stress may be affected by lead exposure as well as antioxidants, yet little is known about the interaction between dietary antioxidants and blood lead levels (BLL) on oxidative stress level. We investigated the interaction between dietary antioxidants and BLL on oxidative stress level. As part of the Biomarker Monitoring for Environmental Health conducted in Seoul and Incheon, Korea, between April and December 2005, we analysed data from 683 adults (female = 47·4 %, mean age 51·4 (sd 8·4) years) who had complete measures on BLL, dietary intakes and oxidative stress marker (urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG)). Dietary intakes were assessed by a validated semi-quantitative FFQ, BLL was measured using atomic absorption spectrophotometry, and 8-OHdG by ELISA. Multivariate linear regression analyses were used to evaluate the influence of BLL on the association between dietary antioxidants and 8-OHdG. Geometric means of BLL and 8-OHdG concentrations were 4·1 (sd 1·5) μg/dl and 5·4 (sd 1·9) μg/g creatinine, respectively. Increases of vitamins C and E were significantly associated with the decrease of log10 8-OHdG in the adults from the lowest quartile of the BLL group (≤ 3·18 μg/dl, geometric mean = 2·36 μg/dl) than those of the highest quartile BLL group (>5·36 μg/dl, geometric mean = 6·78 μg/dl). Regarding antioxidant-related foods, vegetables excluding kimchi showed a higher inverse relationship with 8-OHdG in the lowest quartile BLL group than the highest group. These findings suggest a rationale for lowering the BLL and increasing the intake of dietary antioxidants in the urban population in Korea.

Protective role of puerarin on lead-induced alterations of the hepatic glutathione antioxidant system and hyperlipidemia in rats

Puerarin (PU), a natural flavonoid, has been reported to have many benefits and medicinal properties. The aim of the present study was to investigate the effects of puerarin on hepatic oxidative stress and hyperlipidemia in rats exposed to lead. Our data showed that puerarin significantly prevented lead-induced hepatotoxicity, indicated by both diagnostic indicators of liver damage (serum aminotransferase levels) and histopathological analysis. Moreover, lead-induced profound elevation of ROS production and oxidative stress, as evidenced by increasing of lipid peroxidation level, reducing of GPx, GST, GR and GCL activities and depleting of intracellular reduced GSH level in liver, were suppressed by treatment with puerarin. Furthermore, the increase of serum cholesterol, triglycerides and LDL induced by lead was effectively suppressed by puerarin. The HDL level in the lead treatment rats was also increased by puerarin. Western blot analysis showed that puerarin remarkably inhibited hyperlipidemia by regulating the expression of cholesterol 7a-hydroxylase (CYP7A1), 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR) and low-density lipoprotein receptor (LDL-R) in liver of lead treated rats. Altogether, these results suggest that puerarin could protect the lead-induced liver injury and hyperlipidemia by reducing ROS production, renewing the activities of antioxidant enzymes and influencing expression of hepatic lipid biosynthesis and metabolism genes.

The association between total urinary arsenic concentration and renal dysfunction in a community-based population from central Taiwan

Arsenic (As) is an important environmental toxicant that can cause cancer and cardiovascular disease, but the relationship between As exposure and renal dysfunction is not clear. The aim of this study is to examine the association between As exposure and renal dysfunction in a community-based population in central Taiwan. One thousand and forty-three subjects were recruited between 2002 and 2005. The risk for type 2 diabetes was increased by 2-fold (p<0.05) in subjects with total urinary As (U-As)>75 μg g(-1) creatinine as compared with subjects whose U-As was ≤ 35 μg g(-1) creatinine after the adjustment for potential confounders. The adjusted odds ratio for an abnormal β2 microglobulin (B2MG>0.154 mg L(-1)) was significantly higher in subjects with U-As>35 μg g(-1) creatinine as compared with the reference group adjusted for age, sex, living area, cigarette smoking, diabetes, and hypertension. The risk for abnormal B2MG and estimated glomerular filtration rate (eGFR<90 mL min(-1)(1.73 m(2))(-1)) was both increased around 2-fold (p<0.05) in subjects with U-As>75 μg g(-1) creatinine as compared with those with U-As ≤ 35 μg g(-1) creatinine adjusted for all the risk factors plus lead (Pb), cadmium and nickel. The prevalence of abnormal B2MG was 4.82 times higher in subjects with both over the median levels of U-As (85.1 μg L(-1)) and urinary Pb (18.9 μg L(-1)) as compared to both lower than the median (p<0.001). These results indicate that U-As might relate to renal dysfunction even other important risk factors were taken into account. Follow-up studies for causal inference are warranted.

Low-level lead exposure increases systolic arterial pressure and endothelium-derived vasodilator factors in rat aortas

Chronic lead exposure induces hypertension and alters endothelial function. However, treatment with low lead concentrations was not yet explored. We analyzed the effects of 7 day exposure to low lead concentrations on endothelium-dependent responses. Wistar rats were treated with lead (1st dose 4 µg/100 g, subsequent dose 0.05 µg/100 g, i.m. to cover daily loss) or vehicle; blood levels attained at the end of treatment were 9.98 µg/dL. Lead treatment had the following effects: increase in systolic blood pressure (SBP); reduction of contractile response to phenylephrine (1 nM–100 µM) of aortic rings; unaffected relaxation induced by acetylcholine (0.1 nM–300 µM) or sodium nitroprusside (0.01 nM–0.3 µM). Endothelium removal, N^G-nitro-L-arginine methyl ester (100 µM) and tetraethylammonium (2 mM) increased the response to phenylephrine in treated rats more than in untreated rats. Aminoguanidine (50 µM) increased but losartan (10 µM) and enalapril (10 µM) reduced the response to phenylephrine in treated rats. Lead treatment also increased aortic Na⁺/K⁺-ATPase functional activity, plasma angiotensin-converting enzyme (ACE) activity, protein expression of the Na⁺/K⁺-ATPase alpha-1 subunit, phosphorylated endothelial nitric oxide synthase (p-eNOS), and inducible nitric oxide synthase (iNOS). Our results suggest that on initial stages of lead exposure, increased SBP is caused by the increase in plasma ACE activity. This effect is accompanied by increased p-eNOS, iNOS protein expression and Na⁺/K⁺-ATPase functional activity. These factors might be a compensatory mechanism to the increase in SBP.

H2O2 regulation of vascular function through sGC mRNA stabilization by HuR

OBJECTIVE

Hydrogen peroxide (H(2)O(2)) is an important mediator in the vasculature, but its role in the regulation of soluble guanylate cyclase (sGC) activity and expression is not completely understood. The aim of this study was to test the effect of H(2)O(2) on sGC expression and function and to explore the molecular mechanism involved.

METHODS AND RESULTS

H(2)O(2) increased sGCβ1 protein steady-state levels in rat aorta and aortic smooth muscle cells (RASMCs) in a time- and dose-dependent manner, and this effect was blocked by catalase. sGCα2 expression increased along with β1 subunit, whereas α1 subunit remained unchanged. Vascular relaxation to an NO donor (sodium nitroprusside) was enhanced by H(2)O(2), and it was prevented by ODQ (sGC inhibitor). cGMP production in both freshly isolated vessels and RASMCs exposed to H(2)O(2) was greatly increased after sodium nitroprusside treatment. The H(2)O(2)-dependent sGCβ1 upregulation was attributable to sGCβ1 mRNA stabilization, conditioned by the translocation of the mRNA-binding protein HuR from the nucleus to the cytosol, and the increased mRNA binding of HuR to the sGCβ1 3' untranslated region. HuR silencing reversed the effects of H(2)O(2) on sGCβ1 levels and cGMP synthesis.

CONCLUSIONS

Our results identify H(2)O(2) as an endogenous mediator contributing to the regulation of vascular tone and point to a key role of HuR in sGCβ1 mRNA stabilization.

Apocynin attenuates pressure overload-induced cardiac hypertrophy in rats by reducing levels of reactive oxygen species

It has been shown that angiotensin II (Ang II) is involved in cardiac remodeling mediated by NADPH oxidase-dependent reactive oxygen species (ROS). Accordingly, NADPH oxidase-dependent ROS may play a role in cardiac hypertrophy induced by pressure overload. In the present study, we sought to determine whether inhibition of NADPH oxidase prevents cardiac hypertrophy. After abdominal aorta banding to induce cardiac hypertrophy, rats were treated for 8 weeks with apocynin (Apo) or captopril (Cap). Measures of cardiac hypertrophy were evaluated. Treatment with Cap or Apo reduced the left ventricle/body weight ratio (LV/BW), LV transnuclear myocyte diameter, and atrial natriuretic factor (ANF) mRNA expression relative to those of untreated rats subjected to aorta banding. The activity of NADPH oxidase and the ROS levels were decreased in treated animals. Cap, but not Apo, decreased Ang II levels and inhibited expression of p22phox and p67phox in LVs. In conclusion, local expression of Ang II appears to contribute to pressure overload-induced cardiac hypertrophy by upregulating NADPH oxidase expression and promoting ROS synthesis. Inhibition of NADPH oxidase and elimination of ROS may prevent or repair damage due to cardiac hypertrophy.

Quercetin protects the rat kidney against oxidative stress-mediated DNA damage and apoptosis induced by lead

Quercetin, a flavonoid, effectively improved the lead-induced histology changes including structure damage and leukocyte infiltration in rat kidney. The present study was designed to explore the protective mechanism of quercetin against lead-induced oxidative DNA damage and apoptosis in rat kidney. We found that quercetin markedly decreased the ROS level and lowered the GSH/GSSG ratio in the kidney of lead-treated rat. The increase of 8-hydroxydeoxyguanosine level in the kidney of lead-treated rat was effectively suppressed by quercetin. Furthermore, quercetin markedly restored Cu/Zn-SOD, CAT and GPx activities in the kidney of lead-treated rat. TUNEL assay showed that lead-induced apoptosis in rat kidney was significantly inhibited by quercetin, which might be attributed to its antioxidant property. In conclusion, these results suggested that quercetin could protect the rat kidney against lead-induced injury by improving renal function, attenuating histopathologic changes, reducing ROS production, renewing the activities of antioxidant enzymes, decreasing DNA oxidative damage and apoptosis.

Acute toxicity study of the interaction between titanium dioxide nanoparticles and lead acetate in mice

Titanium dioxide (TiO(2)) is one kind of widely used nanoparticle, which was used as a solid-phase extraction to preconcentrated and measured of lead (Pb) in river water and seawater. However the interaction of nanoparticle TiO(2) and Pb was unknown. The aim of this study is to investigate the potential acute toxicity of the interaction between nanoparticle TiO(2) (50 and 120nm) and lead acetate (PbAC) in adult mice. The animals were randomly divided into six groups: a control group and five treatment groups (TiO(2)-50, TiO(2)-120, PbAC, TiO(2)-50+PbAC and TiO(2)-120+PbAC groups). Suspensions of TiO(2) (5g/kg body weight), PbAC (500mg/kg body weigh) and TiO(2) (5g/kg body weight)+PbAC (500mg/kg body weigh) were administrated to mice via oral gavage, respectively. Seven days later, the animals were sacrificed after being anesthetized by ether. There were no significant changes of the body weight coefficients of liver, kidney and brain. However, the results of liver function and nephrotoxicity examination revealed that there were serious damages to liver and kidney between the group treated with the mix suspension and the one with TiO(2). After the mix suspension treatment, ROS levels were significantly increased in liver but not in kidney, cortex and hippocampus. There were no increase of MDA levels in these tissues, and no activity reductions of SOD and GSH-Px in liver and kidney but in the cortex and hippocampus. Therefore, though our results have not suggested that TiO(2) particle and PbAC have a synergistic acute toxicity in mice after oral administration, PbAC may increase the acute toxicity of TiO(2) nanoparticle in some degree. The potential toxic mechanism maybe related with oxidative damages.

Lead contributes to arterial intimal hyperplasia through nuclear factor erythroid 2-related factor-mediated endothelial interleukin 8 synthesis and subsequent invasion of smooth muscle cells

OBJECTIVE

To validate the hypothesis that the toxic heavy metal lead (Pb) may be linked to cardiovascular diseases via the initiation of atherosclerosis, in vivo and in vitro studies were conducted.

METHODS AND RESULTS

During the human study part of this project, serum Pb levels of healthy young women were correlated to carotid intima-media thickness. Multivariate logistic regression analyses showed that increased serum Pb levels were significantly associated with an increased intima-media thickness (P=0.01; odds ratio per SD unit, 1.6 [95% CI, 1.1 to 2.4]). In vitro, Pb induced an increase in interleukin 8 production and secretion by vascular endothelial cells. Nuclear factor erythroid 2-related factor-2 is the crucial transcription factor involved in Pb-induced upregulation of interleukin 8. Endothelial cell-secreted interleukin 8 triggered intimal invasion of smooth muscle cells and enhanced intimal thickening in an arterial organ culture model. This phenomenon was further enhanced by Pb-increased elastin synthesis of smooth muscle cells.

CONCLUSIONS

Our data support the hypothesis that Pb is a novel, independent, and significant risk factor for intimal hyperplasia.

Protective effect of N-acetylcysteine on experimental chronic lead nephrotoxicity in immature female rats

Oxidative stress plays a key role in lead (Pb)-induced nephrotoxicity. N-acetylcysteine (NAC) is a potent oxygen free radicals scavenger and a metal chelator. In the present study, female Sprague-Dawley rats received PbAc(2) (300 mg/L, via drinking water) and/or NAC (100 mg/kg/day, by intraperitoneal injection) to investigate the protective effect of NAC on Pb-induced renal damage and oxidative stress as well as its mechanism of action. Renal toxicity was evaluated by measuring urinary excretion of total protein, beta(2)-microglobulin, albumin and urinary enzyme markers of tubular necrosis, as well as serum urea nitrogen level. Activities of antioxidant enzymes, contents of glutathione and malondialdehyde in kidney were also measured. Renal cell damage was assessed by electron microscopy. Animals that received both Pb and NAC showed a better renal function than those receiving Pb alone. Lead-induced tubular lesions and mitochondrial damage were markedly reduced in rats that also received NAC. Also, NAC significantly reduced the levels of lipid peroxidation and markedly restored the enzymic and non-enzymatic antioxidants levels in kidney of Pb-treated rats. Moreover, NAC administration significantly increased urinary Pb excretion and decreased its level in the serum and kidney. In conclusion, NAC treatment prevents renal tubular damage induced by chronic Pb administration, most probably through its antioxidant properties and chelating ability.

Quercetin protects rat liver against lead-induced oxidative stress and apoptosis

Quercetin, a flavonoid, effectively improved the lead-induced histology changes including structure damage and leukocyte infiltration in rat liver. The present study was designed to explore the protective mechanism of quercetin against lead-induced hepatic injury. We found that quercetin markedly decreased the MDA and H(2)O(2) levels and lowered the GSH/GSSG ratio in the liver of lead-treated rat. Moreover, quercetin markedly restored Cu/Zn-SOD, Mn-SOD, CAT and GPx activities and upregulated mRNA expression levels of these proteins in the liver of lead-treated rat. Western blot analysis showed that quercetin significantly inhibited apoptosis by modulating the ratio of Bax to Bcl-2 expression and suppressing the expression of phosphorylated JNK1/2 and cleaved caspase-3 in the liver of lead-treated rat. In conclusion, these data suggest that quercetin protects the rat liver from lead-induced injury by attenuating lipid peroxidation, renewing the activities of antioxidant enzymes and inhibiting apoptosis.

Amelioration of lead-induced hepatotoxicity by Allium sativum extracts in Swiss albino mice

Lead is a blue-gray and highly toxic divalent metal that occurs naturally in the earth's crust and is spread throughout the environment by various human activities. The efficacy of garlic (Allium sativum) to reduce hepatotoxicity induced by lead nitrate was evaluated experimentally in male mice. Oral treatment with lead nitrate at a dose of 50 mg/kg body weight daily for 40 days (1/45 of LD₅₀) induced a significant increase in the levels of hepatic aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, acid phosphatase, cholesterol, lipid peroxidation, and lead nitrate. In parallel, hepatic protein levels in lead-exposed mice were significantly depleted. Lead nitrate exposure also produced detrimental effects on the redox status of the liver indicated by a significant decline in the levels of liver antioxidants such as superoxide dismutase, catalase, and glutathione. After exposure to lead nitrate (50 mg/kg body weight for 10 days), the animals received aqueous garlic extract (250 mg/kg body weight and 500 mg/kg body weight) and ethanolic garlic extract (100 mg/kg body weight and 250 mg/kg body weight), and partially restored the deranged parameters significantly. Histological examination of the liver also revealed pathophysiological changes in lead nitrate-exposed group and treatment with garlic improved liver histology. Our data suggest that garlic is a phytoantioxidant that can counteract the deleterious effects of lead nitrate.

Amelioration of lead-induced hepatotoxicity by Allium sativum extracts in Swiss albino mice

Lead is a blue-gray and highly toxic divalent metal that occurs naturally in the earth's crust and is spread throughout the environment by various human activities. The efficacy of garlic (Allium sativum) to reduce hepatotoxicity induced by lead nitrate was evaluated experimentally in male mice. Oral treatment with lead nitrate at a dose of 50 mg/kg body weight daily for 40 days (1/45 of LD(50)) induced a significant increase in the levels of hepatic aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, acid phosphatase, cholesterol, lipid peroxidation, and lead nitrate. In parallel, hepatic protein levels in lead-exposed mice were significantly depleted. Lead nitrate exposure also produced detrimental effects on the redox status of the liver indicated by a significant decline in the levels of liver antioxidants such as superoxide dismutase, catalase, and glutathione. After exposure to lead nitrate (50 mg/kg body weight for 10 days), the animals received aqueous garlic extract (250 mg/kg body weight and 500 mg/kg body weight) and ethanolic garlic extract (100 mg/kg body weight and 250 mg/kg body weight), and partially restored the deranged parameters significantly. Histological examination of the liver also revealed pathophysiological changes in lead nitrate-exposed group and treatment with garlic improved liver histology. Our data suggest that garlic is a phytoantioxidant that can counteract the deleterious effects of lead nitrate.

Increased cyclic guanosine monophosphate production and endothelial nitric oxide synthase level in mononuclear cells from sildenafil citrate-treated patients with erectile dysfunction

Mononuclear cells express enzymes involved in the NO/cyclic guanosine monophosphate (cGMP) generating system, as well as PDE5. The objective of the study was to determine the effect of sildenafil citrate administration on the level of proteins involved in the NO/cGMP generating system in mononuclear cells from patients with ED. Twenty-one patients with ED (International Index of Erectile Function-Erectile Function Domain (IIEF-EFD) 17.9+/-0.8) were enrolled and 100 mg sildenafil citrate on-demand was administered during 12 weeks. All patients showed cardiovascular risk factors. After sildenafil citrate administration, IIEF-EFD score was improved (26+/-1.2 P<0.05). In the mononuclear cells, the protein level of endothelial NO synthase (eNOS) was higher after sildenafil citrate treatment. It was accompanied by reduction in the circulating plasma levels of both high-sensitive C-reactive protein and soluble intercellular adhesive molecule-1. The protein level of soluble guanylate cyclase and PDE5 did not change in the mononuclear cells after sildenafil citrate treatment. However, in the mononuclear cells exogenous NO induced a higher cGMP production after 12-weeks sildenafil citrate administration. In conclusion, in mononuclear cells from patients with ED sildenafil citrate administration increased the level of eNOS protein and increased cGMP production in response to NO. Moreover, sildenafil citrate administration reduced the plasma circulating levels of two biomarkers associated with inflammation.

Inhibition of bilirubin metabolism induces moderate hyperbilirubinemia and attenuates ANG II-dependent hypertension in mice

Population studies indicate that moderate hyperbilirubinemia is associated with reduced incidence of cardiovascular diseases, including hypertension. Despite this correlative evidence, no studies have directly tested the hypothesis that moderate increases in plasma bilirubin levels can attenuate the development of hypertension. This hypothesis was tested by treating mice with Indinavir, a drug that competes with bilirubin for metabolism by UDP-glucuronosyltransferase 1A1 (UGT1A1). Treatment of mice with Indinavir (500 mg x kg(-1) x day(-1), gavage) resulted in a twofold increase in plasma unconjugated bilirubin levels. Next, we determined the effect of Indinavir-induced changes in plasma bilirubin on the development of ANG II-dependent hypertension. Moderate hyperbilirubinemia was induced 3 days before the implantation of an osmotic minipump that delivered ANG II at a rate of 1 microg x kg(-1) x min(-1). ANG II infusion increased mean arterial pressure (MAP) by 20 mmHg in control mice but by only 6 mmHg in mice treated with Indinavir (n = 6). Similar to Indinavir treatment, direct infusion of bilirubin (37.2 mg x kg(-1) x day(-1) i.v.) resulted in a twofold increase in plasma bilirubin levels and also attenuated the development of ANG II-dependent hypertension. Moderate hyperbilirubinemia resulted in an increase in plasma nitrate/nitrite levels, which averaged 36 +/- 2 vs. 50 +/- 7 microM in ANG II vehicle vs. Indinavir-treated mice (n = 5). Moderate hyperbilirubinemia resulted in attenuation of vascular oxidative stress as determined by dihydroethidium staining of aortic segments. These results indicate that moderate hyperbilirubinemia prevents ANG II-dependent hypertension by a mechanism that may involve decreases in vascular oxidative stress.