Toxicodynamics of Lead, Cadmium, Mercury and Arsenic- induced kidney toxicity and treatment strategy: A mini review

Assessment of the toxicity and biochemical effects of detergent processed cassava on renal function of Wistar rats

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The acute toxicity showed increase mortality with increased detergent concentration.

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Plasma and urine creatinine and urea was found to be high in the treated rats.

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Renal photomicrographs showed distorted pattern of corpuscles and tubules.

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The practice of adding detergent to cassava should be discontinued.

Fufu is a major component of food in West Africa. Local cassava farmers use detergent to ferment cassava root tuber during processing into fufu. Studies have established the hazardous health effects of detergent in humans. This study was carried out to determine the median lethal toxicity of detergent-processed cassava, and assessed its effects on the renal function of male Wistar rats. Fufu with different concentrations of detergent (250, 500 and 750 g/l) were given as food twice daily to the rats for the acute toxicity study. The sub-chronic test lasted for four weeks, during which the fufu samples prepared with 10, 20, 30, 40 and 50 g/l of detergent, were separately given to five groups of five rats, respectively. The results of the acute toxicity test showed increase in mortality with corresponding increase in detergent concentration. Plasma and urine creatinine and urea concentrations of all the detergent-treated rats were significantly higher than that of the negative and positive controls. Urinalysis showed significant presence of glucose and ketone bodies, as well as, blood and protein. Renal photomicrographs showed deranged cortical structure with diffuse loss of tubules, inflammatory cells infiltrate in the interstitium. The study concluded that detergent-processed cassava has adverse effects on the structure and function of the kidneys of rats.

The mercury level in hair and breast milk of lactating mothers in Iran: a systematic review and meta-analysis

Exposure to mercury is one of the major global health concerns due to its stability, bioaccumulation and high toxicity. Therefore, the present study was conducted to assess the mean mercury level in hair and breast milk (BM) of Iranian lactating mothers (ILMs) through meta-analysis technique. We conducted a systematic literature search in online electronic databases included main domestic databases (SID, Magiran, Iran medex, Medlib and ISC) and international databases (Embase, Scopus and PubMed) for studies published between 2000 up 2018. Each process of research and evaluation of articles based on inclusion and exclusion criteria is done by two researchers, individually. From10 studies entered to meta-analysis process including 556 ILM, the mean hair mercury level (HML) and mean milk mercury level (MML) was estimated to be 0.15 μg/g (95 CI: 0.11-0.19, I2: 47.6%, P: 0.028) and 0.51 μg/l (95 CI: 0.28-0.74, I2: 1.9%, P: 0.421), respectively. In this meta-analysis, the mean HML and mean MML were estimated to be lower than the standard of World Health Organization (WHO). Although the mean mercury level in hair and BM of ILMs was lower than the WHO standard, but due to toxicity and serious concern of health, management and Periodic monitor are recommended in different cities of the country for evaluate the mercury levels in hair and BM of ILMs and to estimate the infant's exposure.

Secoisolariciresinol diglucoside protects against cadmium-induced oxidative stress-mediated renal toxicity in rats

BACKGROUND

Cadmium is a well known environmental pollutant and strong toxic heavy metal, that causes oxidative damage to various organs of the body, including the kidney. Cadmium (II) chloride (CdCl2) is a water-soluble crystalline form, which exhibits a higher affinity with chlorides at the target site. The current study examined the protective effects of Secoisolariciresinol diglucoside (SDG), a principal lignan extracted from flaxseeds against CdCl2-induced renal toxicity in rats.

METHODS

Twenty four healthy male Wistar rats with four groups of six animals each were used in the study. Group-1- Control was administered with saline. Group-2 -was treated with SDG; Group-3 with CdCl2 alone, and Group-4 were treated with CdCl2 plus SDG. The effect of Cd on kidney was assessed in terms of various parameters like lipid peroxidation, production of Nitric oxide (NO) and Myeloperoxidase (MPO), and kidney function markers like uric acid, urea, and creatinine. The levels of antioxidant molecules like glutathione content and the activities of superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase were also measured, apart from histopathological studies.

RESULTS

The animals that received CdCl2, exhibited changes in the concentration of Cd in the kidney. The levels of kidney function markers like uric acid, urea, and creatinine were found to be abnormal in serum, and also there was a drastic decrease in the levels of glutathione content and the activities of superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase. The treatment of SDG significantly decreased (p < 0.05) the levels of NO and MPO in the animals treated with CdCl2 plus SDG when compared to the animal group treated with CdCl2 alone. The treatment of SDG before CdCl2 injection exhibited significant changes in the activity of the antioxidant enzymes, which was evidenced by the restoration in their activities, when compared to CdCl2 alone treated group (p < 0.05), as observed in the results of histopathology.

CONCLUSIONS

The findings of the present investigation suggested that SDG exhibited anti-oxidant, anti-apoptotic and renoprotective properties. Thus, SDG may act as a supramolecular binding component and naturally occurring metal chelating agent for metal cations like Cd2+. Therefore, flaxseed lignan-SDG can be used as a therapeutic agent against nephrotoxicity caused by cadmium. However, detailed future studies are needed to know the underlying mechanism of action of SDG against the Cd and other heavy metals induced nephrotoxicity.

Cadmium sulfide-induced toxicity in the cortex and cerebellum: In vitro and in vivo studies

Living organisms have an innate ability to regulate the synthesis of inorganic materials, such as bones and teeth in humans. Cadmium sulfide (CdS) can be utilized as a quantum dot that functions as a unique light-emitting semiconductor nanocrystal. The increased use in CdS has led to an increased inhalation and ingestion rate of CdS by humans which requires a broader appreciation for the acute and chronic toxicity of CdS. We investigated the toxic effects of CdS on cerebellar cell cultures and rat brain. We employed a 'green synthesis' biosynthesis process to obtain biocompatible material that can be used in living organisms, such as Viridibacillus arenosi K64. Nanocrystal formation was initiated by adding CdCl2 (1 mM) to the cell cultures. Our in vitro results established that increased concentrations of CdS (0.1 μg/mL) lead to decreased cell viability as assessed using 3-[4,5-dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide (MTT), total antioxidant capacity (TAC), and total oxidant status (TOS). The in vivo studies showed that exposure to CdS (1 mg/kg) glial fibrillary acidic protein (GFAP) and 8-hydroxy-2' -deoxyguanosine (8-OHdG) were increased. Collectively, we describe a model system that addresses the process from the synthesis to the neurotoxicity assessment for CdS both in vitro and in vivo. These data will be beneficial in establishing a more comprehensive pathway for the understanding of quantum dot-induced neurotoxicity.

The Footprints of Oxidative Stress and Mitochondrial Impairment in Arsenic Trioxide-Induced Testosterone Release Suppression in Pubertal and Mature F1-Male Balb/c Mice via the Downregulation of 3β-HSD, 17β-HSD, and CYP11a Expression

Exposure to arsenic (AS) causes abnormalities in the reproductive system; however, the precise cellular pathway of AS toxicity on steroidogenesis in developing F1-male mice has not been clearly defined. In this study, paternal mice were treated with arsenic trioxide (As₂O₃; 0, 0.2, 2, and 20 ppm in drinking water) from 5 weeks before mating until weaning and continued for male offspring from weaning until maturity (in vivo). Additionally, Leydig cells (LCs) were isolated from the testes of sacrificed F1-intact mature male mice and incubated with As₂O₃ (0, 1, 10, and 100 μM) for 48 h (in vitro). Biomarkers of mitochondrial impairment, oxidative stress, and several steroidogenic genes, including the steroidogenic acute regulatory (StAR) protein, cytochrome P450 side-chain cleaving enzyme (P450scc; Cyp11a), 3β-hydroxysteroid dehydrogenase (3β-HSD), and 17β-hydroxysteroid dehydrogenase (17β-HSD), were evaluated. High doses of As₂O₃ interrupted testosterone (T) biosynthesis and T-related gene expression in these experimental models. Altogether, overconsumption of As₂O₃ can cause testicular and LC toxicity through mitochondrial-related pathways and oxidative stress indices as well as downregulation of androgenic-related genes in mice and isolated LCs. These results could lead to the development of preventive/therapeutic procedures against As₂O₃-induced reproductive toxicity. Graphical Abstract Mohammad Mehdi Ommati and Reza Heidari contributed equally to this study.

Enhancement of Pb (II) adsorption by boron doped ordered mesoporous carbon: Isotherm and kinetics modeling

Boron doped ordered mesoporous carbon (BMC) was prepared to improve the adsorption of Pb(II). The effects of several parameters such as contact time, pH, and ionic strength on the adsorption by both pristine ordered mesoporous carbon (OMC) and BMC were investigated. Thermodynamic, sorption isotherm and adsorption kinetics models were used to study the adsorption mechanisms by each of the adsorbents. Based on intraparticle diffusion model, the adsorption process by the two adsorbents mainly involved the quick liquid-film diffusion stage and slow pore diffusion portion, and fitting experimental data with Temkin model indicates that the adsorption process by both of the adsorbents involve physisorption and chemisorption. Based on Langmuir model, the estimated maximum adsorption capacity for BMC was about 1.3 times higher than the pristine OMC. Moreover, BMC retained good adsorption performance in tap and lake water, and could be regenerated effectively and recycled using EDTA. The results suggested that BMC, with enhanced adsorption performance compared with OMC, could be considered as very effective and promising materials for Pb (II) removal from wastewater.

Changes in rat myocardium contractility under subchronic intoxication with lead and cadmium salts administered alone or in combination

Subchronic intoxications induced in male rats by repeated intraperitoneal injections of lead acetate and cadmium chloride, administered either alone or in combination, are shown to affect the biochemical, cytological and morphometric parameters of blood, liver, heart and kidneys. The single twitch parameters of myocardial trabecular and papillary muscle preparations were measured in the isometric regime to identify changes in the heterometric (length-force) and chronoinotropic (frequency-force) contractility regulation systems. Differences in the responses of these systems in trabecules and papillary muscles to the above intoxications are shown. A number of myocardium mechanical characteristics changing in rats under the effect of a combined lead-cadmium intoxication and increased proportion of α-myosin heavy chains were observed to normalize fully or partially if such intoxication was induced against background administration of a proposed bioprotective complex. Based on the experimental results and literature data, some assumptions are suggested concerning the mechanisms of the cardiotoxic effects produced by lead and cadmium.

Xanthones protects lead-induced chronic kidney disease (CKD) via activating Nrf-2 and modulating NF-kB, MAPK pathway

Xanthones from a tropical fruit of Garcinia mangostana L. is known to possess a wide spectrum of pharmacologic properties, including antioxidant, anti-bacterial, anti-inflammatory, and antidiabetic activities. The current study aimed to assess the possible protective effects of xanthones against lead acetate (PbAc)-induced chronic kidney disease (CKD). To accomplish, in vitro antioxidant assays of xanthones, in vivo oxidative stress parameters, histopathology, inflammatory parameters were evaluated using PbAc-induced IRC male mice. The study was supported by in silico molecular docking of respective organ receptor protein-ligand interaction. Results revealed that xanthones potentially scavenged the DPPH, superoxide, hydroxyl, and nitric oxide radicals. Oxidative stress, kidney dysfunction, inflammatory markers, and kidney apoptosis increased by PbAc were attenuated with the co-treatment of xanthones. The treatment remarkably improved the tissue architecture. Of note, in silico prediction of activity study showed that protective role of xanthones could be due to its efficacy to activate the Nrf-2, regulate the intracellular [Ca2+], as well as downregulate the NF-kB, MAPK pathway. In a nutshell, xanthones could be a potential candidate for the management of PbAc-induced kidney damage.

Effects of combined administration of calcium, iron, zinc, chrysanthemum flavonoids, and DMSA on the treatment of lead intoxication in mice

The effect of combined administration of calcium (Ca), iron (Fe), zinc (Zn), chrysanthemum flavonoids, and meso-2,3-dimercaptosuccinic acid (DMSA) on the treatment of lead (Pb) intoxication in mice was studied. One hundred ninety female mice (SPF level, aged 18-22 days) were randomly divided into two groups as experimental animals. Mice in group I (10 mice) served as normal control animals, and were administered deionized water containing 12.5 μL/L acetate acid for 6 weeks, whereas mice in group II (180 mice) were exposed to 0.1% (wt/vol) of lead acetate in deionized water for 6 weeks and served as experimental animals. After 6 weeks of successful modeling, 180 mice from group II (lead-exposed) were divided into 18 groups of 10 mice each, 16 of which were treated by the combined administration of Ca, Fe, Zn, chrysanthemum flavonoids, and DMSA by L16 (215 ) orthogonal design. The remaining two groups were given treatment with low and high doses of DMSA, respectively. After three weeks of intervention (ig), the optimal treatment group was identified according to its blood lead level, as well as some antioxidant indices in the blood, liver, and hippocampus. The results indicated that the combined administration of Fe, Zn, chrysanthemum flavonoids, and DMSA with low dosage had the most significant effect on increasing the activities of blood delta-aminolevulinic acid dehydratase and superoxide dismutase (SOD), hepatic SOD and hippocampus nitric oxide synthase while decreasing the blood lead level, the content of hepatic malondialdehyde and hippocampus nitric oxide; this was considered the optimal treatment group. There was no difference in the level of blood hemoglobin between the optimal treatment group and the model control group (the first group of the orthogonal experiment). The activities of blood glutathione (GSH), hepatic GSH and glutathione peroxidase of the optimal treatment group were the same as other groups', and the recovery of the related indexes in the optimal effect group closely resembled the high dosage DMSA group. It can be concluded that the coadministration of Fe, Zn, and chrysanthemum flavonoids along with a low-dose DMSA effectively reduces Pb poisoning and lead-induced oxidative damage in lead-exposed mice; the result may provide a theoretical reference for the treatment of Pb poisoning.

Effect of arsenic and/or fluoride gestational exposure on renal autophagy in offspring mice

Both arsenic (As) and fluorine (F) are toxic substances widely found in the environment, which threaten to various organs of both human and animals, especially the kidney. In this study, to investigate the individual and combined effects of arsenic (15 mg/L As₂O₃(III)) and fluoride (100 mg/L NaF), arsenic (15 mg/L As₂O₃(III)) and fluoride-arsenic (15 mg/L As₂O₃(III)+100 mg/L NaF) on the renal autophagy during early life, a mouse model of gestationally exposed to As and/or F was established. The results showed that the mRNA expression levels of LC3, LC3I, LC3II, Beclin-1, ULK1, Atg13 and Atg14 were significantly increased with a concomitant decrease in mTOR and Bcl-2 up on individual exposure to As and F rather than in combined (As + F) exposure. In addition, the protein expression levels of LC3-II/LC3-I, Beclin-1, and LAMP1 were significantly increased with a concomitant decrease in mTOR and Bcl-2 in the mice subjected to individual exposure than the combined exposure. Based on the results, it was observed that renal tissue of mice was highly sensitive to F than As. Moreover, the toxicity of the combined (As + F) exposure was significantly lower than that of the individual exposure, which could be attributed due to the antagonism between As and F.

Antioxidant and Nephroprotective Effects of Okra Pods Extract (Abelmoschus esculentus L.) against Lead Acetate-Induced Toxicity in Mice

In this study, we determine the curative effects of okra pods (Abelmoschus esculentus L.) extract against lead acetate toxicity in mice kidney. n-Hexane, ethyl acetate, and methanol solvent were used for extracting okra pods. The role of the extract as an antioxidant was tested by DPPH and FRAP methods. The methanol extract was used for experiments in animals. A total of 30 male BALB/c mice were randomly divided into six equal groups: normal control, negative control (lead-induced), and treatment groups (lead-induced for 28 days and administration of methanol extract at doses of 50, 100, 200, and 400 mg/kg BW for the 28 days). The following were analyzed in all groups: activity of the antioxidant enzymes, namely, superoxide dismutase (SOD) and catalase (CAT); oxidant level, namely, malondialdehyde (MDA) and nitric oxide (NO); and markers of kidney injury, namely, blood urea nitrogen (BUN) and creatinine (Cre). Kidney histopathology was also evaluated. This study showed that the methanol extract showed the highest antioxidant activity (IC₅₀ is 35.21 µg/mL, and FRAP is 57.58 µM Fe^2+/g). The CAT and SOD activities increased significantly in okra-treated groups (P < 0.05). The okra administration groups experienced a significant decrease in MDA, NO, BUN, and Cre levels (P < 0.05). Thickness of the epithelial proximal tubule, diameter of the proximal tubule, and percentage of necrotic cells in proximal tubule decreased, but the diameter ratio of glomerular Bowman's capsule in mice treated with okra was optimally improved and repaired like normal control (P < 0.05). The results of this study reveal that methanol extract has a very strong antioxidant effect and can reduce the influence of toxicity induced by lead acetate in mice kidney.

Hepatorenal protective effect of flaxseed protein isolate incorporated in lemon juice against lead toxicity in rats

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Flaxseed protein isolate (FPI) is a good source of protein with potent antioxidant activity.

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Solubility and scavenging radical activity of FPI increased in the acidic medium.

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Lead intoxication elevated lipid peroxidation of kidney, urinary protein and creatinine as well as kidney and liver functions.

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lemon juice and FPI are considered protective sources of kidney and liver against lead toxicity.

Finding renal and hepatoprotective agents preferably with antioxidant activities against environmental pollutants especially lead which can adversely affect liver and kidney is a great demand. In the current study, flaxseed protein isolate (FPI) was extracted from defatted flaxseed meal. Amino acids profile, antioxidant capacity and solubility of the extracted FPI were determined. The solubility of FPI in the acidic media was exploited in preparation of lemon juice with FPI. Twenty four male rats were assigned to four groups; normal control, lead intoxicated (oral daily dose of 60 mg/kg b.w. in distilled water for four weeks), lead intoxicated and orally administrated with daily dose equal 1 ml of lemon juice as well as lead intoxicated and orally administered with FPI (daily dose equal 100 mg/kg) in 1 ml of lemon juice. The oral administration of FPI incorporated in lemon juice suppressed the elevation in kidney functions, lipid peroxidation of kidney tissues, urinary protein and creatinine as well as liver functions caused by lead intoxication. Additionally, lemon juice with FPI combated the reduction of GSH of kidney tissues. It was revealed also that lemon juice without FPI suppressed the elevation in kidney and liver functions caused by lead. It can be concluded that flaxseed protein isolate is a good source of protein with potent antioxidant activity. Additionally, lemon juice and FPI are considered protective sources of kidney and liver against lead toxicity.

Further verification of some postulates of the combined toxicity theory: New animal experimental data on separate and joint adverse effects of lead and cadmium

Outbred male rats were repeatedly injected intraperitoneally two-level sub-lethal doses of lead acetate and/or cadmium chloride solutions 3 times a week during 6 weeks. The animals developed explicit, even if moderate, subchronic intoxication characterized by a large number of indices, both common to both metals (including increased DNA fragmentation coefficient) and lead-specific. Special attention was paid to hemodynamic and electrocardiographic effects. The combined action of lead and cadmium was modeled with the help of the Response Surface Methodology to obtain additional support for the previously substantiated postulates of combined toxicity's typological ambiguity. This is dependent on which particular effect comes under consideration, on its level, and on the acting dose ratio. For one and the same toxic combination, the type of combined toxic action can vary from synergistic to contra-directional. In particular, the actions of lead and cadmium on blood pressure were found to be opposite in direction. Furthermore, it is shown once again that the systemic toxic effects of a metal combination, its in vivo genotoxicity included, can be more or less attenuated by background administration of a theoretically justified composition of biologically active agents.

Cadmium exposure triggers mitochondrial dysfunction and oxidative stress in chicken (Gallus gallus) kidney via mitochondrial UPR inhibition and Nrf2-mediated antioxidant defense activation

Cadmium (Cd) is a widespread environmental pollutant that accumulates in living systems and represents a significant global health hazard. Cd poses a toxicity threat to both human and animal health, including that of birds. Further knowledge of Cd toxicology pathways will allow for a better understanding of Cd-induced nephrotoxicity. To evaluate Cd-induced nephrotoxicity through potential oxidative damage, male chickens were treated with 0 mg/kg, 35 mg/kg or 70 mg/kg CdCl₂ in diet for 90 days. Markedly, histopathology indicated renal tubular epithelial cell swelling, renal function CREA content abnormalities, biochemical and morphologic indices indicative of Cd-induced kidney injury. Cd toxicity induced the up-regulation of Nrf2 and downstream target genes that relieve oxidative stress. Meanwhile, Cd disrupted the homeostasis of trace elements and promoted oxidative damage. Cd interfered with mitochondrial unfolded protein response (UPR^mt)-related factors (SIRT1, SIRT3, PGC-1α, TFAM, Nrf1, and HTRA2) and disrupted the homeostasis of mitochondrial dynamics (OPA1, MFN1, MFN2, Fis1 and MFF), thereby exacerbating mitochondrial structural damage and mitochondrial dysfunction. In conclusion, our study demonstrated that the nephrotoxicity of Cd exposure results in oxidative stress and mitochondrial dysfunction by activating the Nrf2 signaling pathway and inhibiting UPR^mt in the kidneys.

Nephrotoxic metals of cadmium, lead, mercury and arsenic and the odds of kidney stones in adults: An exposure-response analysis of NHANES 2007-2016

BACKGROUND

Nephrotoxic metals of arsenic, cadmium, lead and mercury exposures are common environmental pollutants. The associations between arsenic, cadmium, lead and mercury exposures and the risk of kidney stones are unclear.

OBJECTIVE

To explore the associations between biomarkers of arsenic, cadmium, lead and mercury exposures and the odds of kidney stones.

METHODS

Adult participants (≥20 years) from the 2007-2016 NHANES were included. Restricted cubic splines were adopted.

RESULTS

The odds ratio (95% confidence interval) of kidney stones increased with increasing blood cadmium and reached the maximum at 1.00 μg/L [1.38 (1.02-1.88) overall, 1.62 (1.11-2.32) for women and 1.53 (1.06-2.22) for non-Hispanic white]. The odds of kidney stones increased with increasing urinary cadmium and reached the maximum at 1.50 μg/L [2.56 (1.17-5.59) overall, 5.57 (1.88-16.49) for women, 4.31 (1.75-10.63) for obese individuals and 3.75 (1.60-8.78) for non-Hispanic white]. The odds of kidney stones increased with increasing total urinary arsenic and urinary dimethylarsinic acid in women, and reached the maximum of 1.69 (1.08-2.67) at 40 μg/L and 1.71 (1.07-2.72) at 10.00 μg/L, respectively. Inverse associations were found between the odds of kidney stones and blood lead within 5.00 μg/dL [0.64 (0.46-0.90) overall, 0.53 (0.33-0.84) for men and 0.58 (0.37-0.92) for non-Hispanic white], methyl mercury within 3.00 μg/L [non-obese individuals: 0.71 (0.51-0.99)] and urinary arsenous acid within 1.20 μg/L [individuals other than non-Hispanic white: 0.63 (0.41-0.95)]. No association was found with other biomarkers.

CONCLUSIONS

Several biomarkers of arsenic, cadmium, lead and mercury exposures were associated with the odds of kidney stones in adults.

Co-exposures to toxic metals cadmium, lead, and mercury and their impact on unhealthy kidney function

Cross-sectional data (N = 25427) from the National Health and Nutrition Examination Survey for 2003-2014 for US adults were used to estimate the impact of co-exposure to high levels of cadmium, lead, and mercury on the unhealthy kidney function. If observed concentrations of cadmium, lead, and total mercury were above the 75th percentile of their respective distributions, the exposure to the corresponding metal was considered to be high. Logistic regression models were fitted to estimate the probabilities of an unhealthy kidney function. Two alternate definitions of unhealthy kidney function were used. First, if estimated, glomerular filtration rate (eGFR) was < 60 mL/min/1.73 m² (K_eGFR) and second, if the observed albumin creatinine ratio (ACR) was ≥ 30 mg/g creatinine (K_ACR). As compared with low exposures, adjusted odds ratios (AOR) for unhealthy kidney function when exposed to high levels of lead and cadmium were observed to be 1.567 (1.346-1.823) and 1.663 (1.376-2.010) respectively for K_eGFR. When exposed to high levels of both cadmium and lead, AORs for unhealthy kidney functions K_eGFR and K_ARC were found to be 2.369 (1.868-3.004) and 1.522 (1.216-1.905) respectively. When exposed to high levels of cadmium, lead, and mercury, AORs for unhealthy kidney functions K_eGFR and K_ARC were found to be 2.248 (1.428-3.538) and 1.502 (1.024-2.204) respectively. High exposure to lead along with any level of exposure to cadmium and total mercury was found to adversely affect the health of kidney function. High exposure to mercury does not affect unhealthy kidney function.

Golden mussel (Limnoperna fortunei) as a bioindicator in aquatic environments contaminated with mercury: Cytotoxic and genotoxic aspects

This study evaluated the Limnoperna fortunei (golden mussel) as a bioindicator of cytotoxicity and genotoxicity in aquatic environments contaminated by heavy metals. Five groups of 50 subjects each were exposed to different concentration of mercuric chloride (HgCl₂) (0.001 mg/L, group I; 0.005 mg/L, group II; 0.01 mg/L, group II; 0.02 mg/L, group IV; and 0.1 mg/L, group V). The control group for both chronic and acute treatment did not receive HgCl₂. For chronic exposure, the respective groups were placed in aquaria with water contaminated with the above concentrations of HgCl₂. For acute exposure, the different concentrations of HgCl₂ were injected into the posterior adductor muscle of the individuals belonging to the aforementioned groups. The biological matrix used in the tests was the whole body muscle. Tests (cell viability assay, alkaline comet test; enumeration of micronuclei and necrotic cells, quantification of Hg content in tissues and water, and histopathological analysis of tissues), were carried out on the 7th, 15th, and 30th treatment days or 2 h after injection. Our results demonstrated that L. fortunei showed cell damage in both chronic and acute exposure groups. Significant DNA damage was observed at both the 15th (0.1 mg/L) and 30th (0.01-0.1 mg/L) days of chronic exposure. However, in acute treatment all concentrations induced DNA breaks. The presence of necrosis increased at all concentrations tested for both acute and chronic exposure. Tissue mercury retention on the 15th day was higher than on the 30th day of exposure, while in the same period, there was a decrease in the mercury content of aquarium water. Taking the data together, it is concluded that L. fortunei as a possible bioindicator of the quality of aquatic environments.

Interaction of epitaxial graphene with heavy metals: towards novel sensing platform

Development of next-generation sensors based on graphene materials, especially epitaxial graphene (EG) as the most promising representative, with desirable cross-reactivity to heavy metals (HMs) is of great technological significance in the virtue of enormous impact on environmental sensorics. Nevertheless, the mechanisms by which EG responds to toxic HMs exposure and then produces the output signal are still obscure. In the present study, the nature of interaction of toxic HMs, e.g. Cd, Hg and Pb in neutral charge state and EG on Si-face SiC in the absence and in the presence of pure water solution has been investigated using density functional theory with the inclusion of dispersion correction and cluster model of EG. The gas-phase calculations showed that adsorbed electron-donating Cd and Hg adatoms on EG are most stable when bonded to hollow sites, while Pb species prefer to sit above bridge sites. By using non-covalent interaction analysis, charge decomposition analysis, overlap population density of states analysis and topological analysis, it was found that the interaction between Cd or Hg and EG is non-bonding in nature and is mainly governed by van der Waals forces, while Pb adsorption is followed by the formation of anti-bonding orbitals in vacuum conditions and bonding orbitals in water. The role of solvent in the adsorption behavior of HMs is studied and discussed. The present theoretical analysis is in good agreement with recent experimental results towards discriminative electrochemical analysis of the toxic HMs in aqueous solutions at critically low concentrations.

Role of Autophagy on Heavy Metal-Induced Renal Damage and the Protective Effects of Curcumin in Autophagy and Kidney Preservation

Curcumin is a hydrophobic polyphenol compound extracted from the rhizome of turmeric. The protective effect of curcumin on kidney damage in multiple experimental models has been widely described. Its protective effect is mainly associated with its antioxidant and anti-inflammatory properties, as well as with mitochondrial function maintenance. On the other hand, occupational or environmental exposure to heavy metals is a serious public health problem. For a long time, heavy metals-induced nephrotoxicity was mainly associated with reactive oxygen species overproduction and loss of endogenous antioxidant activity. However, recent studies have shown that in addition to oxidative stress, heavy metals also suppress the autophagy flux, enhancing cell damage. Thus, natural compounds with the ability to modulate and restore autophagy flux represent a promising new therapeutic strategy. Furthermore, it has been reported in other renal damage models that curcumin’s nephroprotective effects are related to its ability to regulate autophagic flow. The data indicate that curcumin modulates autophagy by classic signaling pathways (suppression of protein kinase B (Akt)/mammalian target of rapamycin (mTOR) and/or by stimulation of adenosine monophosphate-activated protein kinase (AMPK) and extracellular signal-dependent kinase (ERK) pathways). Moreover, it allows lysosomal function preservation, which is crucial for the later stage of autophagy. However, future studies of autophagy modulation by curcumin in heavy metals-induced autophagy flux impairment are still needed.

A Systematic Review on the Influences of Neurotoxicological Xenobiotic Compounds on Inhibitory Control

Background: Impulsive and compulsive traits represent a variety of maladaptive behaviors defined by the difficulties to stop an improper response and the control of a repeated behavioral pattern without sensitivity to changing contingencies, respectively. Otherwise, human beings are continuously exposed to plenty neurotoxicological agents which have been systematically linked to attentional, learning, and memory dysfunctions, both preclinical and clinical studies. Interestingly, the link between both impulsive and compulsive behaviors and the exposure to the most important xenobiotic compounds have been extensively developed; although the information has been rarely summarized. For this, the present systematic review schedule and analyze in depth the most important works relating different subtypes of the above-mentioned behaviors with 4 of the most important xenobiotic compounds: Lead (Pb), Methylmercury (MeHg), Polychlorinated biphenyls (PCB), and Organophosphates (OP) in both preclinical and clinical models.

Methods: Systematic search strategy on PubMed databases was developed, and the most important information was structured both in text and in separate tables based on rigorous methodological quality assessment.

Results: For Lead, Methylmercury, Polychlorinated biphenyls and organophosphates, a total of 44 (31 preclinical), 34 (21), 38 (23), and 30 (17) studies were accepted for systematic synthesis, respectively. All the compounds showed an important empirical support on their role in the modulation of impulsive and, in lesser degree, compulsive traits, stronger and more solid in animal models with inconclusive results in humans in some cases (i.e., MeHg). However, preclinical and clinical studies have systematically focused on different subtypes of the above-mentioned behaviors, as well as impulsive choice or habit conformations have been rarely studied.

Discussion: The strong empirical support in preclinical studies contrasts with the lack of connection between preclinical and clinical models, as well as the different methodologies used. Further research should be focused on dissipate these differences as well as deeply study impulsive choice, decision making, risk taking, and cognitive flexibility, both in experimental animals and humans.

Lead and kidney: Concentrations, variabilities, and associations across the various stages of glomerular function

Data (N = 9882) from National Health and Nutrition Examination Survey for 2003-2014 for US adults aged ≥20 years were analyzed to evaluate the variabilities in concentrations of blood and urine lead across various stages of glomerular function. Those who had estimated glomerular filtration rate (eGFR) >90 mL/min/1.73 m² were defined to be in glomerular function stage 1 (GF-1), those who had eGFR between 60 and 90 mL/min/1.73 m² were defined to be in GF-2, those who had eGFR between 45 and 60 mL/min/1.73 m² were defined to be in GF-3A, those who had eGFR between 15 and 45 mL/min/1.73 m² were defined to be in GF-3B/4. There were consistent increases in adjusted geometric means (AGM) for both blood and urine lead from GF-1 to GF-3A even though increases were not uniform from one GF stage to another. For the total population, AGMs for blood lead were 1.23, 1.78, 2.25, and 2.25 μg/dL for GF-1, GF-2, GF-3A, and GF-3B/4 respectively. AGMs for urine lead were 0.49, 0.61, 0.68, and 0.47 μg/L for GF-1, GF-2, GF-3A, and GF-3B/4 respectively. Thus, from GF-3A to GF-3B/4, AGMs for both blood and urine lead decreased. However, percent increases from GF-1 to GF-3A for urine lead were smaller than for blood lead and percent decreases from GF-3A to GF-3B/4 for urine lead were larger than for blood lead. Females had lower AGMs than males for both blood and urine lead. Also, smoker-nonsmoker differences for blood lead narrowed as kidney function deteriorated but smoker-nonsmoker differences for urine cadmium lead as kidney function deteriorated. Smokers had sharper increases in AGMs for blood and urine lead than nonsmokers from GF-1 to GF-3A but at GF-3B/4, this difference was reduced to 0.17 μg/dL.

Hepato-Renal protective Effects of Egyptian Purslane Extract against Experimental Cadmium Toxicity in Rats with Special Emphasis on the Functional and Histopathological Changes

The study was designed to clarify the hapato-nephroprotective effects of purslane ethanolic extract (PEE) against cadmium toxicity. Cadmium (Cd) is a toxic heavy metal. Cd occurs as environmental and food/ feed contamination causing public and animals health hazards. Liver and kidney are the main target organs for acute and chronic cadmium toxicity. Portulaca oleracea is rich in several vitamins, minerals, antioxidant components, and omega-3 fatty acids mainly α-linolenic acid and eicosapentaenoic acid. Results showed significant elevation of the liver and kidney functions, lipid profile and lipid peroxidation. In contrast to the antioxidants enzymatic were greatly decreased. The hepatic and renal tissues showed severe degeneration and necrosis accompanied by severe congestion and multifocal hemorrhages in Cd intoxicated rats. All parameters and tissues showed no changes in rates-treated with both Cd and purslane extract as compared with the control rats. The administration of PEE provided a significantly protection against Cd-induced hepato-nephrotoxicity.

Aromatic ginger (Kaempferia galanga L.) extracts with ameliorative and protective potential as a functional food, beyond its flavor and nutritional benefits

Aromatic ginger (Kaempferia galanga L) is native to India and believed to be originated in Burma. Despite substantial uses in a pickle and south-east Asian cuisines, aromatic ginger is chemically less studied than white and red ginger. Multi-directional investigations have been performed to evaluate chemical composition, nutritional values, ameliorative and protective potential of aromatic ginger (Kaempferia galanga) rhizome (KGR). Macro and micro components analysis confirmed that KGR contains protein, fiber, and high amount of essential minerals (potassium, phosphorous, and magnesium) along with appreciable amounts of iron, manganese, zinc, cobalt, and nickel. The anti-proliferative potential of KGR evaluated nine human cell lines. We have evaluated the anti-proliferative potential of hydrodistillate, extract, and key compound isolated from KGR on nine human cancer cell line and also reporting the safety to normal peritoneal macrophage cells. The current study demonstrates the anticancer potential of the KGR on MDA-MB-231 and WRL-68 cells. Very likely, results can be extrapolated to an animal or human system. Ethyl p-methoxy cinnamate (EPMC) was responsible for inhibiting the proliferation action which varied in a tested cell by intracellular reactive oxygen species (ROS) production. The present study demonstrates KGR as safe and high energy value medicinal spices with chemo-preventive action, without toxic phytochemicals, and tolerable other anti-nutritional factors.

Toxicological effects of toxic metals (cadmium and mercury) on blood and the thyroid gland and pharmacological intervention by vitamin C in rabbits

Cadmium and mercury are non-biodegradable toxic metals that may cause many detrimental effects to the thyroid gland and blood. Vitamin C has been found to be a significant chain-breaking antioxidant and enzyme co-factor against metal toxicity and thus make them less available for animals. The current study was performed to find the effect of individual metals (cadmium and mercury), their co-administration, and the ameliorative effects of vitamin C on some of the parameters that indicate oxidative stress and thyroid dysfunction. Cadmium chloride (1.5 mg/kg), mercuric chloride (1.2 mg/kg), and vitamin C (150 mg/kg of body weight) were orally administered to eight treatment groups of the rabbits (1. control; 2. Vit C; 3. CdCl₂; 4. HgCl₂; 5. Vit C + CdCl₂; 6. Vit C + HgCl₂; 7. CdCl₂ + HgCl₂, and 8. Vit C + CdCl₂ + HgCl₂). After the biometric measurements of all experimental rabbits, biochemical parameters viz. triidothyronine (T₃), thyroxine (T₄), thyroid-stimulating hormone (TSH), and triglycerides were measured using commercially available kits. The results exhibited significant decline (p < 0.05) in mean hemoglobin, corpuscular hemoglobin, packed cell volume, T₃ (0.4 ± 0.0 ng/ml), and T₄ (26.3 ± 1.6 ng/ml) concentration. While, TSH (0.23 ± 0.01 nmol/l) and triglyceride (4.42 ± 0.18 nmol/l) were significantly (p < 0.05) increased but chemo-treatment with Vit C reduces the effects of Cd, Hg, and their co-administration but not regained the values similar to those of controls. This indicates that Vit C had a shielding effect on the possible metal toxicity. The Cd and Hg also found to accumulate in vital organs when measured by atomic absorption spectrophotometer. The metal concentration trend was observed as follows: kidney > liver > heart > lungs. It was concluded that Cd and Hg are toxic and tended to bioaccumulate in different organs and their toxic action can be subdued by vitamin C in biological systems.

The association between lead and cadmium co-exposure and renal dysfunction

Both cadmium (Cd) and lead (Pb) exposure can induce kidney damage. However, the effects of combined exposure to Cd and Pb on renal function at environmental levels have not been fully clarified. In this study we investigated the renal function in a Chinese population co-exposed to Cd and Pb. A total of 331 subjects (215 women and 116 men), living in either a control or a polluted area, were included in this study. Cd and Pb in blood and urine (BCd, BPb, UCd, and UPb), and kidney effect markers including urinary N-acetyl-β-D-glucosaminidase (UNAG) and estimated glomerular filtration rate (eGFR), were determined, and the association between exposure markers and renal effect biomarkers were analyzed. The exposure levels in the polluted area were significantly higher than in the control area (all p < 0.01). The eGFR of subjects in the polluted area was decreased compared with that in the control area (p < 0.01). The subjects with high BCd/BPb (BCd ≥ 2 μg/L, BPb ≥ 100 μg/L) or high UCd/UPb (UCd ≥ 3 μg/g creatinine, UPb ≥ 10 μg/g creatinine) showed higher UNAG and UALB levels compared with other subgroups (p < 0.01). The probability of having elevated UNAG in subjects with high BCd/BPb was greater than those with low BCd/BPb [odds ratio (OR) = 2.6, 95% confidence interval (CI): 1.4-4.7), low BCd/high BPb (OR =3.1, 95% CI: 1.4-6.6), and high BCd/low BPb (OR = 1.7, 95% CI: 0.9-3.2). The OR of subjects with low UCd and high UPb, high UCd and low UPb, and high UCd/UPb were 2.9 (95% CI: 1.4-5.7), 3.3 (95% CI: 1.5-7.2), and 7.7 (95% CI: 4.0-14.7), respectively, compared with those with low UCd/UPb. The risk of decrease in eGFR was also higher in subjects with high UCd/UPb than for those with low UCd/UPb (OR = 7.2, 95% CI: 0.8-62.2). Our data demonstrate that Cd and Pb exposure, alone or in combination, are associated with renal impairment. In addition, co-exposure to Pb and Cd propagates the renal tubular dysfunction compared with Cd or Pb exposure alone.

The effects of lead on the development of somites in chick embryos (Gallus gallus domesticus) under in vitro conditions: a histological study

Lead (Pb) is one of the most abundant toxic metals in the environment that can cause a variety of harmful effects. During embryonic development of vertebrates, somites are temporary organs that give rise to skeletal muscle, cartilage, tendon, endothelial cells, and dermis. In this study, we investigated the effects of lead on the development of somites and their derivatives in chick embryos under in vitro conditions. For this propose, fertilized eggs of Gallus gallus domesticus were incubated until they reached the stage of 15-20 somites. The somites and notochord were isolated and treated with different concentrations of lead acetate (500, 1000, 2000, and 4000 ng ml-1) for 72 h. Our results indicated that high concentrations of lead reduced the nucleus diameter, reduced the synthesis of collagen, inhibited the formation of the cartilage matrix in somite cells, and disturbed the formation and order of myotubes. In conclusion, the results of the current study for the first time indicated the disturbing effects of lead on the development of somites in the chick embryo. Our results revealed that lead disturbed the development of somites in the chick embryo, which suggested that at high concentrations it can cause a serious mortal danger to life.

Alterations in the properties of sperm protamine-like II protein after exposure of Mytilus galloprovincialis (Lamarck 1819) to sub-toxic doses of cadmium

Protamine-like proteins (PL-II, PL-III and PL-IV) represent the major basic nuclear component of Mytilus galloprovincialis L sperm chromatin. The present study investigates the effects induced on the properties of PL-II protein after exposure of Mytilus galloprovincialis L for 24 h to 1.5 and 5 µM CdCl₂. We found cadmium accumulation in protamine-like proteins with a linear grow up with the exposition dose. In particular, after 5 µM CdCl₂ mussels exposure, the mobility of PL-II band changed in SDS-PAGE, suggesting structural rearrangement in presence of cadmium. Structural analysis using fluorescent probes, indicated that at 5 µM CdCl₂ the complete conformational change of PL-II protein was reached. In the same condition of mussels exposure of 5 µM CdCl₂, PL-II protein changed its DNA binding mode, which determined a closer DNA binding, because higher amount of NaCl were required for PL-II protein release by sperm nuclei. These results supported the hypothesis that mussel exposure to this CdCl₂ dose, although lower to toxic ones, affects the properties of this protein and as a consequence chromatin organization of spermatozoa that is essential for the success of fertilization.

Renal toxicity of heavy metals (cadmium and mercury) and their amelioration with ascorbic acid in rabbits

Cadmium and mercury are among the most toxic and dangerous environmental pollutants that may cause fatal implications. Vitamin C is an important chain-breaking antioxidant and enzyme co-factor against heavy metals. The objective of the present study was to evaluate the toxicological effects of cadmium chloride, mercuric chloride, and their co-administration on biochemical parameters of blood serum and metal bioaccumulation in kidneys and also to elucidate the protective effect of vitamin C in rabbits against these metals. In the current research, cadmium chloride (1.5 mg/kg), mercuric chloride(1.2 mg/kg), and vitamin C (150 mg/kg of body weight) were orally administered to eight treatment groups of the rabbits (1, control; 2, vitamin; 3, CdCl₂; 4, HgCl₂; 5, vitamin + CdCl₂; 6, vitamin + HgCl₂; 7, CdCl₂ + HgCl₂, and 8, vitamin + CdCl₂ + HgCl₂). After the biometric measurements of all experimental rabbits, biochemical parameters viz. creatinine, cystatin C, uric acid, and alkaline phosphatase (ALP) and metal bioaccumulation were determined using commercially available kits and atomic absorption spectrophotometer, respectively. The levels of creatinine (28.3 ± 1.1 μmol/l), cystatin C (1932.5 ± 38.5 ηg/ml), uric acid (4.8 ± 0.1 mg/day), and ALP (51.6 ± 1.1 IU/l) were significantly (P < 0.05) increased due to administration of mercuric chloride but in the presence of vitamin C, the effects of mercuric chloride on creatinine (21.9 ± 1.4 μmol/l), cystatin C (1676.2 ± 42.2 ηg/ml), uric acid (3.9 ± 0.1 mg/day), and ALP (43.3 ± 0.8 IU/l) were less as compared to metal-exposed specimens. Similar results were found in rabbits treated with cadmium chloride and vitamin C and also with co-administration of both metals and vitamin C. Because of the bio-accumulative nature of cadmium chloride and mercuric chloride, these metals were accumulated in kidneys of rabbits, which might lead to deleterious effects. The results of the present study provide an insight into the toxicity of the cadmium chloride, mercuric chloride, and/or their combination on biochemical parameters as well as kidneys of the rabbits and the ameliorating potential of vitamin C against these metals is also evaluated.

The key effects of polymorphism during PbII uptake by calcite and aragonite

The efficiency of Pb uptake by CaCO₃ is different for calcite and aragonite due to surface passivation.

Exposure to mixtures of mercury, cadmium, lead, and arsenic alters the disposition of single metals in tissues of Wistar rats

Humans throughout the world are exposed regularly to mixtures of environmental toxicants. Four of the most common heavy metal toxicants in the environment are mercury (Hg), cadmium (Cd), lead (Pb), and arsenic (As). Numerous studies have assessed the effects and disposition of individual metals in organ systems; however, humans are usually exposed to mixtures of toxicants or metals rather than to a single toxicant. Therefore, the purpose of the current study was to test the hypothesis that exposure to a mixture of toxic heavy metals alters the disposition of single metals in target organs. Wistar rats (Rattus norvegicus) were exposed to Hg, Cd, Pb, or As as a single metal or as a mixture of metals. Rats were injected intravenously for three days, following which kidneys, liver, brain, and blood were harvested. Samples were analyzed for content of Hg, Cd, Pb, and As via inductively coupled plasma mass spectrometry. In general, exposure to a mixture of metals reduced accumulation of single metals in target organs. Interestingly, exposure to mixtures of metals with Pb and/or As increased the concentration of these metals specifically in the liver. The findings from this study indicate that exposure to mixtures of toxic heavy metals may alter significantly the distribution and accumulation of these metals in target organs and tissues.

Alteration in thiols homeostasis, protein and lipid peroxidation in renal tissue following subacute oral exposure of imidacloprid and arsenic in Wistar rats

The aim of present study was to assess whether No Observed Effect Level (NOEL) of imidacloprid (IMI) potentiates the arsenic induced renal toxicity at its maximum contaminant level in drinking water in Wistar rats. Significant elevation of lipid and protein oxidation with reduced level of total thiols and antioxidant enzymes (catalase, superoxide dismutase, glutathione reductase, glutathione peroxidase and glutathione-s-transferase) in renal tissue may have contributed to increased renal plasma biomarkers (creatinine and blood urea nitrogen) following repeated exposure of IMI and arsenic alone and in-combination. The altered renal biomarkers in co-exposed groups corroborated with histopathological alterations in renal tissue. The observations indicated that altered thiol homeostasis in renal tissue may be associated with increased lipid and protein oxidation in IMI and arsenic administered rats. It is concluded that administration of IMI potentiate the arsenic induced renal damage in Wistar rats.