Strategies for Safe and Effective Therapeutic Measures for Chronic Arsenic and Lead Poisoning

Impact of arsenic on male and female reproductive function: a review of the pathophysiology and potential therapeutic strategies

Arsenic is a ubiquitous metalloid and heavy metal that contributes to the global decline in human fertility. Humans are constantly exposed to arsenic through biotic and abiotic sources, especially ingestion of arsenic-contaminated food and water. Its exposure is associated with several adverse health challenges, including reproductive toxicity. In spite of its reported adverse effects, arsenic exposure remains a global challenge. Hence, this study provides a comprehensive review of the literature on the impact and mechanism of arsenic on male and female reproductive function. Additionally, a review of the potential therapeutic strategies is presented. Evidence from the literature reveals that arsenic upregulates reactive oxygen species (ROS) generation which mediates arsenic-induced suppression of the hypothalamic-pituitary-gonadal axis and inactivation of 3β-HSD and 17β-HSD activities, leading to reduced gonadal steroidogenesis. Through several oxidative stress-dependent signaling, arsenic induces the apoptosis of the germ cells, thus contributing to the development of infertility. At the moment, there is no specific treatment for arsenic-induced reproductive toxicity. However, increasing data form the scientific literature reveals the benefits of antioxidants in ameliorating arsenic-induced reproductive toxicity. These molecules suppress ROS generation and maintain optimal activities of the hypothalamic-pituitary-gonadal axis, leading to optimal steroidogenesis and gametogenesis as well as improved germ cells. Overall, this study revealed the impact and associated mechanism of arsenic-induced reproductive toxicity. It also provides evidence from the literature demonstrating potential therapeutic measures in managing arsenic-induced reproductive toxicity.

Proteomic analysis of the effects of Dictyophora polysaccharide on arsenic-induced hepatotoxicity in rats

Arsenic (As) is a highly toxic environmental toxicant and a known human carcinogen. Long-term exposure to As can cause liver injury. Dictyophora polysaccharide (DIP) is a biologically active natural compound found in the Dictyophora with excellent antioxidation, anti-inflammation, and immune protection properties. In this study, the Sprague-Dawley (SD) rat model of As toxicity was established using a feeding method, followed by DIP treatment in rats with As-induced liver injury. The molecular mechanisms of As toxicity to the rat liver and the protective effect of DIP were investigated by proteomic studies. The results showed that 172, 328 and 191 differentially expressed proteins (DEPs) were identified between the As-exposed rats versus control rats (As/Ctrl), DIP treated rats versus As-exposed rats (DIP+As/As), and DIP treated rats versus control rats (DIP+As /Ctrl), respectively. Among them, the expression of 90 DEPs in the As/Ctrl groups was reversed by DIP treatment. As exposure caused dysregulation of metabolic pathways, mitochondria, oxidative stress, and apoptosis-related proteins in the rat liver. However, DIP treatment changed or restored the levels of these proteins, which attenuated the damage to the livers of rats caused by As exposure. The results provide new insights into the mechanisms of liver injury induced by As exposure and the treatment of DIP in As poisoning.

Do Nanoparticles of Calcium Disodium EDTA Minimize the Toxic Effects of Cadmium in Female Rats?

The present study aims to investigate the ability of CaNa2EDTA (ethylenediaminetetraacetic acid) macroparticles and nanoparticles to treat cadmium-induced toxicity in female rats and to compare their efficacies. Forty rats were divided into 4 equal groups: control, cadmium, cadmium + CaNa2EDTA macroparticles and Cd + CaNa2EDTA nanoparticles. Cadmium was added to the drinking water in a concentration of 30 ppm for 10 weeks. CaNa2EDTA macroparticles and nanoparticles (50 mg/kg) were intraperitoneally injected during the last 4 weeks of the exposure period. Every two weeks, blood and urine samples were collected for determination of urea, creatinine, metallothionein and cadmium concentrations. At the end of the experiment, the skeleton of rats was examined by X-ray and tissue samples from the kidney and femur bone were collected and subjected to histopathological examination. Exposure to cadmium increased the concentrations of urea and creatinine in the serum and the concentrations of metallothionein and cadmium in serum and urine of rats. A decrease in bone mineralization by X-ray examination in addition to various histopathological alterations in the kidney and femur bone of Cd-intoxicated rats were also observed. Treatment with both CaNa2EDTA macroparticles and nanoparticles ameliorated the toxic effects induced by cadmium on the kidney and bone. However, CaNa2EDTA nanoparticles showed a superior efficacy compared to the macroparticles and therefore can be used as an effective chelating antidote for treatment of cadmium toxicity.

Toxicity and bioremediation of the lead: a critical review

Lead is a naturally occurring, bluish-gray metal that is found in small quantities in the earth's crust. The existing literature demonstrates that non-biodegradable character and continuous use results in accumulation of lead concentration in the environment and causes various ill effects such as neurotoxicity, change in psychological and behavioral development of different organisms. Nowadays the most effective technique in the revival of the environment is bioremediation and it is environmentally friendly and cost-effective. Bacterial strains such as Oceanobacillus profundus and Lactobacillus acidophilus ATCC4356 have the ability to reduce lead 97% and 73.9%, respectively. Similarly some species of algae and fungal strains also showed lead removal efficiency as 74% (spirulina), 97.1% (Chlorella kessleri), 95.5% (Penicillium janthinillum) and 86% (Aspergillus flavus). Biodegradation of lead by various microbes would be the most efficient and sustainable approach. This review focuses on toxicity, fate of lead in the environment and its microbial degradation.

Thallium uptake and risk in vegetables grown in pyrite past-mining contaminated soil amended with organic fertilizer (compost): A potential method for Tl contamination remediation

Thallium (Tl) is a highly toxic trace metal that can cause severe pollution and damage to the ecological system. In this study, a field trial was conducted in a Tl-rich pyrite-barite past-mining area to unveil the fate of Tl in agricultural practice. Tuscany kale and red chicory cultivated in soil impacted by the dismissed mine of Valdicastello Carducci (Northern Tuscany, Italy) displayed significantly different uptake behaviors of Tl. Hyper-accumulation of Tl was observed in kale leaves and its content reached up to 17.1 mg kg-1 whereas only <0.70 mg kg-1 of Tl was found in leaves of red chicory. Due to the regionally polymetallic pollution, Tuscany kale grown in this area possessed a great Tl intake risk for the residents. As for the fertilization treatment, Tl in Tuscany kale leaves fertilized with mineral fertilizer (NPK) and compost were 21.4 and 12.8 mg kg-1. The results suggested a potential remediation ability of compost in diminishing Tl in the vegetable leaves and thus may reduce its risk in the soil-crop system. Since Tl poisoning emergency may occur in agricultural fields near past-mining zones, it is critical to establish possible remediation measures to ensure food safety surrounding former mining areas likewise.

Uptake of lead by bacteria isolated from industrial effluents and their potential use in bioremediation of wastewater

Due to rising populations and human activities, heavy metals (HM) toxicity has become a serious problem for all life forms. The present study deals with isolating and identifying lead-resistant bacteria from contaminated wastewater of tanneries effluents. Two isolated strains were identified as Bacillus cereus (ID1), and Bacillus sp. (ID3), and both strains resisted a 25 mM concentration of Lead nitrate (Pb (NO3)2). After four days of treatment, Bacillus cereus (ID1) showed 80% lead uptake, and Bacillus sp. (ID3) showed 88%. Lead uptake was confirmed by Energy dispersive X-Ray (EDX) analysis. Fourier transform infrared spectroscopy (FTIR) showed that structural alterations had occurred in functional groups of the treated samples compared to the controls. Our research indicates that these Bacillus strains may be useful in bioremediating heavy metals from polluted environments. Further investigation into the processes involved in the uptake and homeostasis of heavy metals by these strains is required, as is the identification of the genes and enzymes responsible for Pb-bioremediation.

Thymoquinone supplementation mitigates arsenic-induced cytotoxic and genotoxic alterations in rat liver

Arsenic, a widespread environmental toxin, produces multiple organ toxicity, including hepatotoxicity. Thymoquinone (TQ) is known to restore liver functions in several hepatic injury models. This study aims to assess the mitigative potential of TQ against sodium arsenate (NaAs)-induced cytotoxic and genotoxic alterations in the liver. Rats were randomly distributed to control, NaAs, TQ, and NaAs+TQ groups. NaAs+TQ and TQ group of rats were pre-treated with TQ (1.5 mg/kg bwt, orally) for 14 days, and the treatment was further continued for 30 days, with and without NaAs treatment (5 mg/kg bwt, orally), respectively. The deleterious histological alterations in the liver of arsenic intoxicated animals were accompanied by an upsurge in the activities of serum ALT and AST, the diagnostic indicators of liver injury. NaAs caused pronounced alterations in the activities of membrane marker and carbohydrate metabolic enzymes and the enzymatic and non-enzymatic components of hepatic antioxidant defense. Significant hepatocyte DNA damage and hepatic arsenic accumulation were also observed in arsenic-exposed rats. TQ supplementation alleviated these adverse alterations and improved the overall hepatic metabolic and antioxidant status in NaAs-administered rats. Prevention of oxidative injury could be the key mechanism of TQ-elicited protective effects. TQ may have an excellent scope as a dietary supplement in the management of arsenic-induced hepatic pathophysiology.

Effects of Long-Term Lead Exposure on Antioxidant Enzyme Defense System in Organs of Brown Hare (Lepus europaeus Pallas) as a Bioindicator of Environmental Pollution in Croatia

In Croatia, Podravina is a well-known lead-polluted region due to the intensive exploitation of natural gas, a highly developed agricultural industry, and a traffic hub with several heavily traveled roads. It represents a natural environment with a great variety of wildlife, especially hares (Lepus europaeus Pallas), which may serve as an indicator for environmental quality assessment. This study was conducted to estimate the bioaccumulation of lead in hare liver, kidney, muscle, and brain during long-term exposure and its impact on the oxidative status of the organism and to investigate a possible lead exchange ionic mechanism in the brain. In the organs of two hare groups (experimental from polluted area and control from the island of Krk), Ca, Fe, Mg, Na, lead concentrations, and antioxidant enzyme defense system were analyzed. The accumulation of lead was highest in the brain (3.7-fold higher compared to the control group) and lowest in the liver (1.6-fold higher compared to the control group). Kendall-Tau and multiple regression analysis showed that the increased lead content caused a stronger exchange of Ca and Na ions in the brain. We proposed that lead either mobilizes intracellular cation stores or causes competitive displacement of Ca from the binding site in intoxicated cells. A linear predictive model for cell intoxication by lead was proposed, where GPx and SOD were predominantly influenced by long-term lead exposure. The presented results showed that long-term lead exposure in hares negatively affected their oxidative status and caused the strongest toxicity in the brain and muscles, making their survival and/or population vulnerable.

Mutagenic, Carcinogenic, and Teratogenic Effect of Heavy Metals

Heavy metal (HM)-induced toxicity and its associated complications have become a major issue in the medical world. HMs are not biodegradable, enter into the food chain, and gets accumulated in the living systems. Increased concentrations and accumulation of HMs can cause severely damaging effects and severe complications in living organisms and can even lead to the death of the organism. In Ayurvedic medicine, ingredients of natural origin, including whole plants or certain portions of the plant, animal sources, and minerals, are used for therapeutic purposes as medicine, both alone and in combination. HM such as cadmium, copper, zinc, lead, chromium, nickel, and arsenic cause hazardous effects on animals, human health, and the environment. This review focuses on mutagenic, carcinogenic, and teratogenic effects of HM , mechanism, organ toxicity, available remedies in the market, and their side effects. Also, emphasis is given to alternative systems of medicine to treat HM toxicity.

Chemistry, Pharmacology, and Toxicology of Monoisoamyl Dimercaptosuccinic Acid: A Chelating Agent for Chronic Metal Poisoning

Arsenic, a metalloid, is known to cause deleterious effects in various body organs, particularly the liver, urinary bladder, and brain, and these effects are primarily mediated through oxidative stress. Chelation therapy has been considered one of the promising medical treatments for arsenic poisoning. Meso 2,3- dimercaptosuccinic acid (DMSA) has been recognized as one of the most effective chelating drugs to treat arsenic poisoning. However, the drug is compromised with a number of shortcomings, including the inability to treat chronic arsenic poisoning due to its extracellular distribution. Monoisoamyl 2,3-dimercaptosuccinic acid, one of the analogues of meso 2,3-dimeraptosuccinic acid (DMSA), is a lipophilic chelator and has shown promise to be considered as a potential future chelating agent/antidote not only for arsenic but also for a few other heavy metals like lead, mercury, cadmium, and gallium arsenide. The results from numerous studies carried out in the recent past, mainly from our group, strongly support the clinical application of MiADMSA. This review paper summarizes most of the scientific details including the chemistry, pharmacology, and safety profile of MiADMSA. The efficacy of MiADMSA mainly against arsenic toxicity but also a few other heavy metals was also discussed. We also reviewed a few other strategies in order to achieve the optimum effects of MiADMSA, like combination therapy using two chelating agents or coadministration of a natural and synthetic antioxidant (including phytomedicine) along with MiADMSA for treatment of metal/metalloid poisoning. We also briefly discussed the use of nanotechnology (nano form of MiADMSA i.e. nano-MiADMSA) and compared it with bulk MiADMSA. All these strategies have been shown to be beneficial in getting more pronounced therapeutic efficacy of MiADMSA, as an adjuvant or as a complementary agent, by significantly increasing the chelating efficacy of MiADMSA.

Sesamin: Insights into its protective effects against lead-induced learning and memory deficits in rats

BACKGROUND

Lead (Pb) is one of the most hazardous pollutants that induce a wide spectrum of neurological changes such as learning and memory deficits. Sesamin, a phytonutrient of the lignan class, exhibits anti-inflammatory, anti-apoptotic, and neuroprotective properties. The present study was designed to investigate the effects of sesamin against Pb-induced learning and memory deficits, disruption of hippocampal theta and gamma rhythms, inflammatory response, inhibition of blood δ-aminolevulinic acid dehydratase (δ-ALA-D) activity, Pb accumulation, and neuronal loss in rats.

METHODS

Sesamin treatment (30 mg/kg/day; P.O.) was started simultaneously with Pb acetate exposure (500 ppm in standard drinking water) in rats, and they continued for eight consecutive weeks.

RESULTS

The results showed that chronic exposure to Pb disrupted the learning and memory functions in both passive-avoidance and water-maze tests, which was accompanied by increase in spectral theta power and theta/gamma ratio, and a decrease in spectral gamma power in the hippocampus. Additionally, Pb exposure resulted in an enhanced tumor necrosis factor-alpha (TNF-α) content, decreased interleukin-10 (IL-10) production, inhibited blood δ-ALA-D activity, increased Pb accumulation, and neuronal loss of rats. In contrast, sesamin treatment improved all the above-mentioned Pb-induced pathological changes.

CONCLUSION

This data suggests that sesamin could improve Pb-induced learning and memory deficits, possibly through amelioration of hippocampal theta and gamma rhythms, modulation of inflammatory status, restoration of the blood δ-ALA-D activity, reduction of Pb accumulation in the blood and the brain tissues, and prevention of neuronal loss.

Resveratrol and neuroprotection: an insight into prospective therapeutic approaches against Alzheimer's disease from bench to bedside

Alzheimer's disease (AD) is the most common cause of dementia and cognitive impairment; yet, there is currently no treatment. A buildup of Aβ, tau protein phosphorylation, oxidative stress, and inflammation in AD is pathogenic. The accumulation of amyloid-beta (Aβ) peptides in these neurocognitive areas is a significant characteristic of the disease. Therefore, inhibiting Aβ peptide aggregation has been proposed as the critical therapeutic approach for AD treatment. Resveratrol has been demonstrated in multiple studies to have a neuroprotective, anti-inflammatory, and antioxidant characteristic and the ability to minimize Aβ peptides aggregation and toxicity in the hippocampus of Alzheimer's patients, stimulating neurogenesis and inhibiting hippocampal degeneration. Furthermore, resveratrol's antioxidant effect promotes neuronal development by activating the silent information regulator-1 (SIRT1), which can protect against the detrimental effects of oxidative stress. Resveratrol-induced SIRT1 activation is becoming more crucial in developing novel therapeutic options for AD and other diseases that have neurodegenerative characteristics. This review highlighted a better knowledge of resveratrol's mechanism of action and its promising therapeutic efficacy in treating AD. We also highlighted the therapeutic potential of resveratrol as an AD therapeutic agent, which is effective against neurodegenerative disorders.

A Bibliometric Analysis of Research on Selenium in Drinking Water during the 1990-2021 Period: Treatment Options for Selenium Removal

A bibliometric analysis based on the Scopus database was carried out to summarize the global research related to selenium in drinking water from 1990 to 2021 and identify the quantitative characteristics of the research in this period. The results from the analysis revealed that the number of accumulated publications followed a quadratic growth, which confirmed the relevance this research topic is gaining during the last years. High research efforts have been invested to define safe selenium content in drinking water, since the insufficient or excessive intake of selenium and the corresponding effects on human health are only separated by a narrow margin. Some important research features of the four main technologies most frequently used to remove selenium from drinking water (coagulation, flocculation and precipitation followed by filtration; adsorption and ion exchange; membrane-based processes and biological treatments) were compiled in this work. Although the search of technological options to remove selenium from drinking water is less intensive than the search of solutions to reduce and eliminate the presence of other pollutants, adsorption was the alternative that has received the most attention according to the research trends during the studied period, followed by membrane technologies, while biological methods require further research efforts to promote their implementation.

Remediation of noxious wastewater using nanohybrid adsorbent for preventing water pollution

Removal of toxic elements from wastewater effluent has got a lot of attention because of their severe negative effects on human and environmental health. In the past few years, rapid urbanization and industrial activities in developing countries have exacerbated the destruction of the environment. Most of the wastewater effluents are discharged untreated or inadequately treated, which has become a major concern due to its impact on sustainability and the environment. This is imperative to implement, innovative and resourceful wastewater treatment technologies requiring low investment. Among the various treatment technologies, cutting-edge processes in nano-material sciences have recently piqued the interest of scientists. Nanohybrid absorbents have the potential in improving wastewater treatment and increase water supply by utilizing unconventional water resources. Carbon nanotubes, titanium oxide, manganese oxide, activated carbon (AC), magnesium oxide, graphene, ferric oxides, and zinc oxide are examples of nano-adsorbents that are used to eliminate pollutants. This also demonstrated the effective removal of contaminants along with the harmful effects of chemicals, colorants, and metals found in wastewater. The present manuscript examines potential advances in nanotechnology in wastewater treatment for the prevention of water and soil pollution. This systematic review aims to highlight the importance of nanohybrid absorbents treatment technology for wastewater treatment and to explain how nanohybrid absorbents have the potential to revolutionize industrial pollution. There are also other published review articles on this topic but the present review covers an in-depth information on nano-adsorbents and their targeted contaminants.

Evaluation of divalent metal transporter 1 (DMT1) (rs224589) polymorphism on blood lead levels of occupationally exposed individuals

Lead (Pb) is an environmental and public health toxicant. It affects various organ systems of the body, thereby disrupting their normal functions. To date, several genes that are known to influence the mechanism of action of lead and toxicity have been studied. Among them, the iron transporter gene, SLC11A2 (Solute Carrier 11 group A member 2) which codes for the transmembrane protein, DMT1 (Divalent Metal Transporter 1) has shown to transport other metals including zinc, copper, and lead. We investigated the influence of DMT1 polymorphism (rs224589) on blood lead (Pb-B) levels. In the present study, we enrolled 113 lead-exposed workers and performed a comprehensive biochemical analysis and genetic composition. The frequency of DMT1 variants observed in the total subjects (n = 113) was 42 % for homozygous CC wild type, 54 % for heterozygous CA, and 4 % for homozygous AA mutant. The heterozygous CA carriers presented higher Pb-B levels compared to wild type CC and mutant AA carriers. Further, a negative association was observed between Pb-B levels and hemoglobin in heterozygous CA carriers. Hence, C allele may be the risk allele that contributes to increased susceptibility to high Pb-B retention, and genotyping of DMT1 in lead exposed subjects might be used as a prognostic marker to impede organ damage due to lead toxicity.

Blood lead levels in Peruvian adults are associated with proximity to mining and DNA methylation

BACKGROUND

Inorganic lead (Pb) is common in the environment, and is toxic to neurological, renal, and cardiovascular systems. Pb exposure influences the epigenome with documented effects on DNA methylation (DNAm). We assessed the impact of low levels of Pb exposure on DNAm among non-miner individuals from two locations in Peru: Lima, the capital, and Cerro de Pasco, a highland mining town, to study the effects of Pb exposure on physiological outcomes and DNAm.

METHODS

Pb levels were measured in whole blood (n = 305). Blood leukocyte DNAm was determined for 90 DNA samples using the Illumina MethylationEPIC chip. An epigenome-wide association study was performed to assess the relationship between Pb and DNAm.

RESULTS

Individuals from Cerro de Pasco had higher Pb than individuals from Lima (p-value = 2.00E-16). Males had higher Pb than females (p-value = 2.36E-04). Pb was positively associated with hemoglobin (p-value = 8.60E-04). In Cerro de Pasco, blood Pb decreased with the distance from the mine (p-value = 0.04), and association with soil Pb was approaching significance (p-value = 0.08). We identified differentially methylated positions (DMPs) associated with genes SOX18, ZMIZ1, and KDM1A linked to neurological function. We also found 45 differentially methylated regions (DMRs), seven of which were associated with genes involved in metal ion binding and nine to neurological function and development.

CONCLUSIONS

Our results demonstrate that even low levels of Pb can have a significant impact on the body including changes to DNAm. We report associations between Pb and hemoglobin, Pb and distance from mining, and between blood and soil Pb. We also report associations between loci- and region-specific DNAm and Pb.

Aqueous fruit pulp extract of Adansonia digitata (L) protects against lead-acetate-induced hepato-renal damage in rat model

Background

Adansonia digitata (L) fruit has a multi-purpose function one among many, is the antioxidant activities of the fruit by preventing oxidative stress. The effect of Adansonia digitata (L) fruit on lead-induced liver and kidney damage is not clear. Hence, the study was aimed to assessed the protective role of Adansonia digitata (L) fruits against lead acetate induced changes in the liver and kidney function test parameters and the histology of both organ in experimental rats. The rats were divided into five groups with five rats each. All the rats were administered with respective assigned treatment once daily for 6 weeks. Rats in groups I were administered with just distil water (2 ml/kg). Rats in groups II were administered with lead acetate (30 mg/kg) while rats in groups III–V were administered Adansonia digitatata (L) fruit extract (250 mg/kg and 500 mg/kg) and Succimer (5 mg/kg) respectively, then additionally challenged with lead acetate (30 mg/kg) immediately after. At the end of the administration, the blood serum from the experimental rats were used for biochemical analysis. Then, the the organs such as the liver and kidney collected for histological study.

Results

Rats administered with Lead acetate showed an increase in AST, ALP and ALT as well as increase in urea and creatinine level (p < 0.001), when compared with the control group (group I), where as Adansonia digitatata (L) fruit prevented the effect (upsurge of serum, Urea, Creatinine, AST, ALP and ALT) of lead acetate. Rats administer with only Lead acetate revealed marked liver steatosis and the degeneration of the kidney glomerulus. The Adansonia digitatata (L) fruit extract and Succimer prevented the histological liver steatosis, as well as the degeneration of the glomerulus of the kidney cytoarchitecture.

Conclusion

The findings in this study suggest that Adansonia digitata fruits extract has a protective potentials against lead acetate induced liver and kidney toxicity by preventing the upsurge of liver function enzymes and kidney function parameters. Hence, Adansonia digitata fruits can serve as a natural plant agent that can prevent hepato-renal toxicity. Therefore, Adansonia digitata holds future prospects in preclinical framework to ameliorate organs toxicity for oral therapeutic applications.

Evaluation of the Role of KIM-1 in Detecting Early Nephrotoxicity in Lead-Exposed Workers

OBJECTIVES

Lead nephropathy usually starts silent. This study aimed to evaluate using kidney injury molecule 1 (KIM-1) as an early nephrotoxicity predictor of long-term low-level occupational lead exposure.

METHODS

History, examination, and laboratory investigations including: blood lead, urinary KIM-1, serum uric acid, creatinine, urea, sodium, potassium, serum albumin, and urine analysis were done on 35 lead-exposed workers and a matched control group.

RESULTS

Higher blood lead levels were found among the exposed group compared to the control one. No statistically significant difference was found regarding renal failure manifestations or standard renal functions (uric acid, blood urea, and creatinine). Urinary KIM-1 was statistically significantly increased among the exposed group.

CONCLUSION

Renal adverse effects were associated to lead fumes exposure. KIM-1 can be used as biomarker for detecting early renal affection among lead-exposed workers.

Ameliorative effect of ZnO-NPs against bioaggregation and systemic toxicity of lead oxide in some organs of albino rats

Lead is one of the major environmental pollutions worldwide, particularly in developing countries. Though, various occupational and public health measures have been undertaken to control lead exposure. The present study is designed to investigate the role of zinc oxide nanoparticles (ZnO-NPs) to reduce the bioaggregation of lead in the brain, liver, and kidneys and prevent these organ oxidative damage and apoptosis. Twenty male Wistar rats were grouped into 4 gatherings and exposed to the following materials daily on the skin for 2 weeks: 1-normal saline, 2-ZnO-NPs, 3-PbO, and 4-ZnO-NPs+ PbO. Topical application of PbO to rats increased lead contents in blood and different organs causing remarkable oxidative stress damage, apoptosis, and histopathological alterations in these organs. Moreover, PbO-receiving group showed strong positive caspase-3 protein expression with up-regulation of mRNA levels of BAX and COX-2. Co-treatment of ZnO-NPs with PbO could diminish the toxicologic parameters and the above-mentioned immune marker and gene expression levels. Our data suggest the role of ZnO-NPs cream to reduce the risk of lead dermal exposure via preventing absorption and accumulation of it in the internal organs so that it protects these organs from further damage.

Transcriptomic analysis of lead-induced hepatoxicology in female Japanese quails (Coturnix japonica): Implications of triglyceride synthesis, degradation and transport disruption

Lead (Pb) pollution poses great threats to mammals including human and it is also hazardous to bird life. In this study, RNA sequencing analysis was employed to examine the molecular responses to lead exposure in the liver of a toxicological model species Japanese quails (Coturnix japonica). Female birds were exposed to 0, 50, 500 and 1000 ppm waterborne Pb for 49 days. The results showed that hepatic microstructure was damaged under lead exposure featured by sinusoids dilation and irregularity as well as cell necrosis. Moreover, ultrastructural injury in the liver including mitochondrial swelling and vacuolization as well as nuclear deformation was induced by lead exposure. Lead exposure also caused the decrease of lipid droplets in the liver by oil red O staining. In addition, liver transcriptomic analysis revealed that molecular signaling and functional pathways were disrupted by lead exposure. Meanwhile, the expression of genes involved with hepatic glycerophospholipids metabolism of triglyceride synthesis and lipid transport of triglyceride transfer was significantly down-regulated by lead exposure. Moreover, the up-regulation of genes associated with fatty acid oxidation and the down-regulation of genes related with fatty acid synthesis were caused by lead exposure. The present study implied that lead induced liver malfunction and bird health risks through histopathological damages, molecular signaling disruption, genetic expression alteration and triglyceride metabolism disturbance.

Biosynthesized Iron Oxide Nanoparticles from Petroselinum crispum Leaf Extract Mitigate Lead-Acetate-Induced Anemia in Male Albino Rats: Hematological, Biochemical and Histopathological Features

This study aimed to investigate the ameliorative effects of iron oxide nanoparticles (IONPs) prepared from leaf extract of Petroselinum crispum compared to those prepared using a chemical method in lead-acetate-induced anemic rats. Twenty rats were divided into four groups (five rats each). Throughout the experimental period (8 weeks), the rats in group 1 were not given any therapy. The rats in groups 2, 3 and 4 were given 400 ppm lead acetate orally for 2 weeks to make them anemic. Following that, these rats were either left untreated, given 27 ppm of chemical IONPs orally or given 27 ppm of natural IONPs orally for the remaining 6 weeks of the experiment. TEM analysis indicated that the chemically and naturally prepared IONPs had sizes of 6.22–9.7  and 64–68 nm, respectively. Serum ferritin and iron concentrations were reduced, whereas the total iron-binding capacity (TIBC), ALT, AST, urea and creatinine were significantly increased in the non-treated lead-acetate-induced anemic rats compared to those of the control. In addition, congestion, hemorrhage, necrosis, vacuolation and leukocytic infiltration in the kidneys, liver and spleen were observed in non-treated lead-acetate-induced anemic rats compared to the control. The effects of lead acetate were mitigated by IONPs, particularly the natural one. In conclusion, IONPs produced from Petroselinum crispum leaf extract can be used as an efficient and safe therapy in lead-acetate-induced anemic rats.

D-Penicillamine: The State of the Art in Humans and in Dogs from a Pharmacological and Regulatory Perspective

Chelant agents are the mainstay of treatment in copper-associated hepatitis in humans, where D-penicillamine is the chelant agent of first choice. In veterinary medicine, the use of D-penicillamine has increased with the recent recognition of copper-associated hepatopathies that occur in several breeds of dogs. Although the different regulatory authorities in the world (United States Food and Drugs Administration-U.S. FDA, European Medicines Agency-EMEA, etc.) do not approve D-penicillamine for use in dogs, it has been used to treat copper-associated hepatitis in dogs since the 1970s, and is prescribed legally by veterinarians as an extra-label drug to treat this disease and alleviate suffering. The present study aims to: (a) address the pharmacological features; (b) outline the clinical scenario underlying the increased interest in D-penicillamine by overviewing the evolution of its main therapeutic goals in humans and dogs; and finally, (c) provide a discussion on its use and prescription in veterinary medicine from a regulatory perspective.

Arsenate-Induced Changes in Bacterial Metabolite and Lipid Pools during Phosphate Stress

Agrobacterium tumefaciens GW4 is a heterotrophic arsenite-oxidizing bacterium with a high resistance to arsenic toxicity. It is now a model organism for studying the processes of arsenic detoxification and utilization. Previously, we demonstrated that under low-phosphate conditions, arsenate [As(V)] could enhance bacterial growth and be incorporated into biomolecules, including lipids. While the basic microbial As(V) resistance mechanisms have been characterized, global metabolic responses under low phosphate remain largely unknown. In the present work, the impacts of As(V) and low phosphate on intracellular metabolite and lipid profiles of GW4 were quantified using liquid chromatography-mass spectroscopy (LC-MS) in combination with transcriptional assays and the analysis of intracellular ATP and NADH levels. Metabolite profiling revealed that oxidative stress response pathways were altered and suggested an increase in DNA repair. Changes in metabolite levels in the tricarboxylic acid (TCA) cycle along with increased ATP are consistent with As(V)-enhanced growth of A. tumefaciens GW4. Lipidomics analysis revealed that most glycerophospholipids decreased in abundance when As(V) was available. However, several glycerolipid classes increased, an outcome that is consistent with maximizing growth via a phosphate-sparing phenotype. Differentially regulated lipids included phosphotidylcholine and lysophospholipids, which have not been previously reported in A. tumefaciens The metabolites and lipids identified in this study deepen our understanding of the interplay between phosphate and arsenate on chemical and metabolic levels.IMPORTANCE Arsenic is widespread in the environment and is one of the most ubiquitous environmental pollutants. Parodoxically, the growth of certain bacteria is enhanced by arsenic when phosphate is limited. Arsenate and phosphate are chemically similar, and this behavior is believed to represent a phosphate-sparing phenotype in which arsenate is used in place of phosphate in certain biomolecules. The research presented here uses a global approach to track metabolic changes in an environmentally relevant bacterium during exposure to arsenate when phosphate is low. Our findings are relevant for understanding the environmental fate of arsenic as well as how human-associated microbiomes respond to this common toxin.

Low-level Eexposure to lead dust in unusual work schedules and hematologic, renal, and hepatic parameters

BACKGROUND

Many workers are exposed to lead dust in lead-‑zinc mines. Exposure to this heavy toxic metal and its compounds can cause irreversible adverse health effects.

OBJECTIVE

To assess possible hematotoxic, nephrotoxic, and hepatotoxic potentials of low levels of lead in a group of mine workers exposed to this heavy metal in an unusual work schedule.

METHODS

A total of 73 exposed and 70 non-exposed employees were interviewed. Demographic data, and occupational and medical history of the employees were obtained by questionnaires. Air monitoring was performed to determine the workers' time-weighted average (TWA) exposure to lead dust. The threshold limit value (TLV) for lead was adjusted for unusual work schedules according to the model developed by the University of Montreal and the Institute de Recherche en Sante et en Securite du Travail (IRSST). Blood samples were collected for complete blood count, liver and kidney function tests. Data were analyzed using version 21.0 of the SPSS software.

RESULTS

The TWA exposure of workers was 24 μg/m³. On average, the worker's exposure to lead dust did not exceed the 8-h OSHA and ACGIH TLV-TWA of 50 μg/m³. Significant associations were found only between exposure to lead and platelet count, red cell distribution width, total protein, and albumin.

CONCLUSIONS

Exposure to low levels of lead dust in unusual work schedules was not associated with overt hematotoxicity, hepatotoxicity or nephrotoxicity. However, mild, sub-clinical, pre-pathologic significant changes were noted in some blood parameters of the exposed employees as compared with their referent counterparts.

Carcinogenic and non-carcinogenic health risk of arsenic ingestion via drinking water in Langat River Basin, Malaysia

The prolonged persistence of toxic arsenic (As) in environment is due to its non-biodegradable characteristic. Meanwhile, several studies have reported higher concentrations of As in Langat River. However, it is the first study in Langat River Basin, Malaysia, that As concentrations in drinking water supply chain were determined simultaneously to predict the health risks of As ingestion. Water samples collected in 2015 from the four stages of drinking water supply chain were analysed for As concentration by inductively coupled plasma mass spectrometry. Determined As concentrations along with the time series data (2004-2015) were significantly within the maximum limit 0.01 mg/L of drinking water quality standard set by World Health Organization. The predicted As concentration by auto-regression moving average was 3.45E-03 mg/L in 2020 at 95% level based on time series data including climatic control variables. Long-term As ingestion via household filtration water at Langat Basin showed no potential lifetime cancer risk (LCR) 9.7E-06 (t = 6.68; p = 3.37E-08) as well as non-carcinogenic hazard quotient (HQ) 4.8E-02 (t = 6.68; p = 3.37E-08) risk at 95% level. However, the changing landscape, ex-mining ponds and extensive use of pesticides for palm oil plantation at Langat Basin are considered as the major sources of increased As concentration in Langat River. Therefore, a two-layer water filtration system at Langat Basin should be introduced to accelerate the achievement of sustainable development goal of getting safe drinking water supply.

Antioxidative properties of Ocimum gratissimum alters Lead acetate induced oxidative damage in lymphoid tissues and hematological parameters of adult Wistar rats

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Chronic lead toxicity was induced in male rats by oral administration of lead acetate.

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Effect of Ocimum gratissimum in lead acetate toxicity on spleen, thymus, and blood.

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Oral lead acetate administration led to oxidative damage in spleen, thymus and blood.

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Ocimum gratissimum extract reversed oxidative stress and enhanced antioxidant enzymes.

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Ocimum gratissimum averts lead acetate-induced toxicity in the blood, thymus and spleen.

Lead exposure is a well-known environmental hazard. Its accumulation in humans may pose a danger to health. The present study investigated the beneficial effect of Ocimum gratissimum extract (OG) in reducing lead acetate (LA) induced oxidative damage in the spleen, thymus, and hematological indices. We employed an in vivo model of LA induced Wistar rats and administered 125 mg/kg/bw and 250 mg/kg/bw of OG extracts respectively. Our control groups were divided into 2; the first group received normal saline, feed, and water while the second group was administered OG extracts only. We assessed the levels of malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT) in the thymus and spleen and estimated percentages of blood cells. Our results showed that LA induces oxidative damage by significantly elevating MDA and diminishing GSH levels, SOD, and CAT activities. LA administration led to a significant decline in blood parameters. However, co-administration with OG compensated oxidative stress by significantly reducing MDA, increasing GSH, SOD, and CAT. Oral administration of OG to rats attenuated anemia, thrombocytopenia, leucocytosis, eosinophilia, monocytosis, and neutropenia induced by LA. The present study indicates that LA induced Spleen, thymus, and blood toxicity, which was reversed by oral OG administration.

Associations between and risks of trace elements related to skin and liver damage induced by arsenic from coal burning

Long-term exposure to high levels of arsenic has been documented to induce skin and liver damage, affecting hundreds of millions of people. While arsenic-induced skin and liver damage and trace element alterations have been studied, their correlations and risks have not been explained. Based on the above premise, this study included a total of 172 subjects from a coal-burning arsenic poisoning area. The levels of 18 trace elements in hair and six liver function indices in serum were detected, and the associations between and risks of trace elements related to skin and liver damage were analyzed. Finally, the receiver operating characteristic (ROC) curve and areas under the curve (AUC) were used to analyze the diagnostic values of certain trace elements for arsenic-induced skin and liver damage. The results found that a decrease in Se was a risk factor for arsenic-induced skin and liver damage (OR = 8.33 and 1.92, respectively). Furthermore, increases in Al and V were risk factors for arsenic-induced skin damage (OR = 1.05) and liver damage (OR = 13.16), respectively. In addition, the results found that Se and Al possessed certain diagnostic values for arsenic-induced skin damage (AUC = 0.93, 0.80), that Se possessed a diagnostic value for liver damage (AUC = 0.93), and that the combination of Se and Al increased the diagnostic value for skin damage (AUC = 0.96). This study provides an important research basis for further understanding the reasons for arsenic-induced skin and liver damage, for screening and identifying candidate diagnostic biomarkers, and for improving prevention and control strategies for arsenism.

Zinc offers splenic protection through suppressing PERK/IRE1-driven apoptosis pathway in common carp (Cyprinus carpio) under arsenic stress

Arsenic (As) occurs naturally and concentrations in water bodies can reach high levels, leading to accumulation in vital organs like the spleen. Being an important organ in immune response and blood development processes, toxic effects of As on the spleen could compromise immunity and cause associated disorders in affected individuals. Splenic detoxification is key to improving the chances of survival but relatively little is known about the mechanisms involved. Essential trace elements like zinc have shown immune-modulatory effects humans and livestock. This study aimed to investigate the mechanisms involved in As-induced splenic toxicity in the common carp (Cyprinus carpio), and the protective effects of zinc (Zn). Our findings suggest that environmental exposure to As caused severe histological injuries and Ca²⁺ accumulation in the spleen of common carp. Additionally, transcriptional and translational profiles of endoplasmic reticulum stress, apoptosis and autophagy-related genes of the spleen showed upward trends under As toxicity. Treatment with Zn appears to offer protection against As-induced splenic injury in common carp and the pathologic changes above were alleviated. Our results provide additional insight into the mechanism of As toxicity in common carp while elucidating the role of Zn, a natural immune-modulator, as a potential antidote against As poisoning.

Characteristics and mechanisms of Pb(II) sorption onto Fe-rich waste water treatment residue (WTR): A potential sustainable Pb immobilisation technology for soils

Pb contamination of soils is a global problem. This paper discusses the ability of an Fe-rich waste, water treatment residual (WTR), to adsorb Pb(II). This was investigated using batch sorption experiments, X-ray diffraction, electron microprobe microanalysis, PHREEQC modeling and Extended X-ray Absorption Fine Structure (EXAFS) analysis. The WTR is composed of approximately 23 wt. % natural organic matter (NOM), 70 wt. % ferrihydrite and <10 wt. % silicate material. Pb(II) sorption to WTR was dependent on initial Pb(II) load, particle size, time and pH, but not on ionic strength. EXAFS analysis at the Pb L_III-edge confirmed that Pb(II) sorbed to WTR by co-existing bidentate edge-sharing and monodentate or corner-sharing complexes, with 2 O at ∼2.31-2.34 Å, 1 Fe at ∼3.32-3.34 Å, 2 Fe at ∼3.97-3.99 Å and 1 Pb at ∼3.82-3.85 Å. Linear combination showed that the Pb(II)-sorbed spectra were best fit with a ∼0.9 ± 0.1 and 0.1 ± 0.1 contribution from Pb(II)-sorbed ferrihydrite and Pb(II)-sorbed humic acid end members, respectively. Overall, we show that Pb(II) sorbs via strong inner-sphere complexation of Pb(II) to the ferrihydrite component of the WTR, which itself is stable over a wide pH range. Therefore, we suggest that Fe-rich WTR wastes could be used as effective adsorbents in Pb(II)-contaminated soils to help ensure sustainable terrestrial ecosystems.

Exposure of lead on intestinal structural integrity and the diversity of gut microbiota of common carp

Lead is an environmental toxicant that has toxicity effect to the health of aquatic organisms. Gut microbiota has been reported to be closely related to human health. The aim of this study was to investigate the effects of lead exposure on the composition of gut microbiota. The composition of gut microbiota alteration was detected by 16S rRNA gene sequencing, following a 42-day exposure of lead (1 mg/L). The results showed that compared with the normal control group, the carp of lead group showed severe intestinal tissues injury and decreased Zona Occludens 1 (ZO-1) and occludin expression. The production of LPS in serum was increased by the treatment of lead exposure. Our results showed gut bacterial diversity in lead-treated common carp was lower than the control group. At the phylum level, the abundance of Bacteroidetes (LPS producing bacteria) and Fusobacteria in lead-treated carp were much higher than the control carp. And the abundance of Actinobacteria decreased by lead exposure. At the genus level, we found the abundance of Bacteroides (LPS producing bacteria) and Plesiomonas (an important pathogenic bacteria), increased significantly by lead exposure. And the abundance of Akkermansia, a critical probiotics, was markedly inhibited by lead exposure. In conclusion, this study indicated exposure of carp to lead causes gut microbiota alterations and intestinal structural integrity destruction.

(Ascorb)ing Pb Neurotoxicity in the Developing Brain

Lead (Pb) neurotoxicity is a major concern, particularly in children. Developmental exposure to Pb can alter neurodevelopmental trajectory and has permanent neuropathological consequences, including an increased vulnerability to further stressors. Ascorbic acid is among most researched antioxidant nutrients and has a special role in maintaining redox homeostasis in physiological and physio-pathological brain states. Furthermore, because of its capacity to chelate metal ions, ascorbic acid may particularly serve as a potent therapeutic agent in Pb poisoning. The present review first discusses the major consequences of Pb exposure in children and then proceeds to present evidence from human and animal studies for ascorbic acid as an efficient ameliorative supplemental nutrient in Pb poisoning, with a particular focus on developmental Pb neurotoxicity. In doing so, it is hoped that there is a revitalization for further research on understanding the brain functions of this essential, safe, and readily available vitamin in physiological states, as well to justify and establish it as an effective neuroprotective and modulatory factor in the pathologies of the nervous system, including developmental neuropathologies.

Metal toxicity and natural antidotes: prevention is better than cure

Toxicity due to heavy metals (HM), specifically mercury (Hg), arsenic (As), lead (Pb), and cadmium (Cd) remains a challenge to scientists till date. This review gives insights into natural antidotes for the management and prevention of HM toxicity. Various databases such as PubMed, Embase, and Science Direct were searched for available facts on natural antidotes and their commercial products against HM toxicity till date. Toxicity owing to such metals needs prevention rather than therapy. Natural antidotes, fruits and vegetables, rich in antioxidant are the answers to such toxicities. Synthetic chelators impart a major drawback of removing essential metals required for normal body function, along with the toxic one. Natural antioxidants are bestowed with scavenging and chelation properties and can be alternative for synthetic chelating agents. Natural compounds are abundantly available, economic, and have minimal side effects when compared with classical chelators. Prevention is better than cure and thus adding plentiful vegetables and fruits to our diet can combat HM toxicity-related illness. Graphical abstract.

Potential amelioration of waterborne iron toxicity in channel catfish (Ictalurus punctatus) through dietary supplementation of vitamin C

Iron overload in water is a problem in many areas of the world, which could exert toxic effects on fish. To achieve maximum growth and overall fitness, iron induced toxicity must be alleviated. Therefore, this research was undertaken to investigate the potential mitigation of iron toxicity by dietary vitamin C supplementation in channel catfish (Ictalurus punctatus). Two doses of vitamin C (143 and 573 mg/kg diet) were tested against high environmental iron (HEI, 9.5 mg/L representing 25% of 96 h LC₅₀). Fish were randomly divided into six groups with four replicated tanks. The groups were Control (vitamin C deficient feed), LVc (143 mg vitamin C supplemented per kg diet), HVc (573 mg vitamin C supplemented per kg diet), Con + Fe (control exposed to HEI), LVc + Fe (LVc exposed to HEI) and HVc + Fe (HVc exposed to HEI). Following an 8 week trial, there was a significant reduction in weight gain (WG%) in Con + Fe compared to the control, indicating a toxic effect of HEI on fish growth performance. Interestingly, WG% in both LVc + Fe and HVc + Fe groups were significantly higher than Cont + Fe, signifying that HEI inhibited growth, but this was alleviated by vitamin C. Both hemoglobin content and hematocrit were higher in LVc + Fe compared to the control and Con + Fe. In addition, exposure to HEI (Con + Fe) incited hepatic oxidative stress based on an over-accumulation of malondialdehyde (MDA) along with a significant inhibition in superoxide dismutase (SOD) and catalase (CAT) activities; whereas in LVc + Fe and HVc + Fe, the MDA content restored to basal level. A series of histopathological alterations were observed in the liver and gills, with the most severe lesions in Con + Fe, which was also complemented with a remarkable increase in hepatic iron accumulation. Vitamin C supplementations reduced the augmented concentrations of iron accumulation to that of the control. No effect, regardless of the treatments, was noted for fatty acid composition of muscle. Overall, our findings suggest that the vitamin C supplementation can be an effective therapeutic approach for boosting growth as well as alleviating iron toxicity in catfish.

Effects of Essential Trace Elements and Oxidative Stress on Endemic Arsenism Caused by Coal Burning in PR China

Few studies have investigated the association between essential trace elements and oxidative stress in environmental media and populations with endemic arsenism caused by coal burning. Element contents and oxidative stress indicators were measured. Moreover, the expression of genes related to the nuclear factor E2-related factor 2 (Nrf2)/Kelch-like ECH-associated protein 1 (Keap1)-antioxidant response element (ARE) signaling pathway and Nrf2-ARE binding ability is detected. The results show that the contents of arsenic, copper, iron, and chromium were increased in environmental media from the arsenism area compared with the control area; however, the selenium content decreased. The arsenic, iron, chromium, and copper contents and the copper/zinc ratio were also increased in the arsenic-exposed population; however, the selenium content decreased. The results also show that the concentrations of arsenic, iron, and chromium and the copper/zinc ratio increased gradually with the severity of arsenism. However, selenium concentrations decreased gradually with the severity of arsenism. The contents of malondialdehyde, 8-hydroxyldeoxyguanosine, and protein carbonyl in plasma increased, while the levels of sulfhydryl, thioredoxin reductase (TrxR), glutathione peroxidase (Gpx), and superoxide dismutase 1 (SOD1) decreased. The mRNA expression of Keap1 and TrxR1 decreased in the blood, while the mRNA expression of Nrf2, GPx1, and SOD1 increased. Moreover, the Nrf2 protein content and Nrf2-ARE binding ability increased, and the Keap1 protein content decreased. In conclusion, our data suggest that the increased arsenic content in environmental media and populations was accompanied by abnormal levels of essential trace elements. Insufficient selenium intake, copper, and chromium overload and a high copper/zinc ratio might be some of the causes of arsenism, which might be related to the Nrf2/Keap1-ARE signaling pathway.

Heavy Metal-Induced Cerebral Small Vessel Disease: Insights into Molecular Mechanisms and Possible Reversal Strategies

Heavy metals are considered a continuous threat to humanity, as they cannot be eradicated. Prolonged exposure to heavy metals/metalloids in humans has been associated with several health risks, including neurodegeneration, vascular dysfunction, metabolic disorders, cancer, etc. Small blood vessels are highly vulnerable to heavy metals as they are directly exposed to the blood circulatory system, which has comparatively higher concentration of heavy metals than other organs. Cerebral small vessel disease (CSVD) is an umbrella term used to describe various pathological processes that affect the cerebral small blood vessels and is accepted as a primary contributor in associated disorders, such as dementia, cognitive disabilities, mood disorder, and ischemic, as well as a hemorrhagic stroke. In this review, we discuss the possible implication of heavy metals/metalloid exposure in CSVD and its associated disorders based on in-vitro, preclinical, and clinical evidences. We briefly discuss the CSVD, prevalence, epidemiology, and risk factors for development such as genetic, traditional, and environmental factors. Toxic effects of specific heavy metal/metalloid intoxication (As, Cd, Pb, Hg, and Cu) in the small vessel associated endothelium and vascular dysfunction too have been reviewed. An attempt has been made to highlight the possible molecular mechanism involved in the pathophysiology, such as oxidative stress, inflammatory pathway, matrix metalloproteinases (MMPs) expression, and amyloid angiopathy in the CSVD and related disorders. Finally, we discussed the role of cellular antioxidant defense enzymes to neutralize the toxic effect, and also highlighted the potential reversal strategies to combat heavy metal-induced vascular changes. In conclusion, heavy metals in small vessels are strongly associated with the development as well as the progression of CSVD. Chelation therapy may be an effective strategy to reduce the toxic metal load and the associated complications.

Arsenic intoxication: general aspects and chelating agents

Arsenic (As) is widely used in the modern industry, especially in the production of pesticides, herbicides, wood preservatives, and semiconductors. The sources of As such as contaminated water, air, soil, but also food, can cause serious human diseases. The complex mechanism of As toxicity in the human body is associated with the generation of free radicals and the induction of oxidative damage in the cell. One effective strategy in reducing the toxic effects of As is the usage of chelating agents, which provide the formation of inert chelator–metal complexes with their further excretion from the body. This review discusses different aspects of the use of metal chelators, alone or in combination, in the treatment of As poisoning. Consideration is given to the therapeutic effect of thiol chelators such as meso-2,3-dimercaptosuccinic acid, sodium 2,3-dimercapto-1-propanesulfonate, 2,3-dimercaptopropanol, penicillamine, ethylenediaminetetraacetic acid, and other recent agents against As toxicity. The review also considers the possible role of flavonoids, trace elements, and herbal drugs as promising natural chelating and detoxifying agents.

Macro- and microelement content and health risk assessment of heavy metals in various herbs of Iran

In this study, element content and health risk of the most popular herbs from Iran were evaluated. The samples of raw materials from 30 different herbs were purchased from the local markets of Iran. The concentration levels of some elements including macroelements (N, P, K, Ca, and Mg), micronutrients (Fe, Zn, Cu, Mn, and Na), and heavy metals (Cd, Ni, and Pb) of studied herbs were evaluated. The potential of health risks was calculated by Estimated Daily Intake (EDI), Target Hazard Quotient (THQ), and Hazard Index (HI). The analysis of variance (ANOVA) is used to test a hypothesis about differences between the mean values. The highest levels of Ca (20,000 ± 26.3 mg/kg), Mg (9600 ± 45.4 mg/kg), N (59,955 ± 11.55 mg/kg), P (6544 ± 20 mg/kg), and K (56,563.2 ± 18 mg/kg) were found in Zataria multiflora, Malva sylvestris, Acasia arbus, Cannabis sativa, and Amomum subulatum, respectively. In addition, the highest concentration levels of Fe (987 ± 75.27 mg/kg), Zn (1187.5 ± 10 mg/kg), Cu (64.2 ± 2 mg/kg), Mn (272.3 ± 66.62 mg/kg), and Na (2658.8 ± 20.3 mg/kg) were recorded in Bunium persicum, Peganum harmala, Papaver somniferum, Alpinia officinalis, and Cuminum cyminum, respectively. Acasia arbus, Anethum graveolens, and Malva sylvestris showed the highest concentration of Ni (6.07 ± 0.04 mg/kg), Cd (1.64 ± 0.16 mg/kg), and Pb (9.27 ± 0.25 mg/kg). Based on performed health risk assessment on the studied plants, EDI, THQ, and HI values of all of them were less than 1. This study indicated that there were several harmful elements in the herbs. The healthier plant species are those with the least concentration of Pb, Ni, and Cd, which include Vitex agnus-custus and Teucrium polium. On the other hand, the toxic plants with a higher concentration of Pb, Ni, and Cd included Malva sylvestris, Acasia arbus, and Anethum graveolens. In addition, evaluation of human risk assessment is an important factor for investigating the concentration of heavy metals harmful for human beings.

A brief review of the latest pharmacological treatments of COVID-19

New Coronavirus which is called 2019-nCoV (2019-Novel-Coronavirus) or SARS-Cov-2 (Severe Acute respiratory Syndrome-Coronavirus 2) causes deadly pneumonia that first appeared in December 2019 in Wuhan city in China. This virus spreads all over the world quickly and made several problems for the community and healthcare system. Several drugs have been tried to manage COVID-19; however, our knowledge of this virus is not complete. At any rate, effective treatment or vaccine for this disease has not been discovered yet. Furthermore, to achieve this goal, more studies are needed on the structure of the virus and its pathogenesis mechanism. In this article, we summarized several articles suggesting treatments of COVID-19.

Risk Assessment of Contamination by Potentially Toxic Metals: A Case Study in the Vicinity of an Abandoned Pyrite Mine

Abandoned mining areas can display soil and water pollution and also a high incidence of endemic diseases. Here, based on preliminary results on mental retardation and high incidence rates of cancers, we investigate the contamination status and potential ecological risk at an abandoned pyrite mine located in Xianju village, Hubei province, central China. The study focused on the three potentially toxic metals As, Pb, and Zn and four other common elements, including Ca, Fe, S, and Se. Soil samples were collected from 12 sites and leachate seeping from five sites. Leachates were strongly acidic compared to the soil, with pH values <3.22. Soil As and Se concentrations exceeded the Chinese Grade II standards for soil environmental quality (GB 15618-2009) (30 and 3 mg·kg−1, respectively), ranging from 33.6 ± 0.7 to 78.2 ± 1.0 mg As·kg−1 dry matter (DM) and 5.3 ± 0.8 to 17.1 ± 1.4 mg Se·kg−1 DM. Arsenic, Fe, Se, and S in leachates all exceeded the Chinese Grade III standard for surface water environmental quality (GB 3838-2002) (0.1, 0.3, 0.03, and 1.0 mg·L−1). The potential ecological risks from Pb and Zn in soils were low, but As in soils and leachates represented a moderate or strong risk to children according to the Nemerow index and hazard quotient. Soil replacement combined with further remediation measures is required to remediate the contaminated area.

Heavy-Metals-Mediated Phospholipids Scrambling by Human Phospholipid Scramblase 3: A Probable Role in Mitochondrial Apoptosis

Human phospholipid scramblases are a family of four homologous transmembrane proteins (hPLSCR1-4) mediating phospholipids (PLs) translocation in plasma membrane upon Ca²⁺ activation. hPLSCR3, the only homologue localized to mitochondria, plays a vital role in mitochondrial structure, function, maintenance, and apoptosis. Upon Ca²⁺ activation, hPLSCR3 mediates PL translocation at the mitochondrial membrane enhancing t-bid-induced cytochrome c release and apoptosis. Mitochondria are important target organelles for heavy-metals-induced apoptotic signaling cascade and are the central executioner of apoptosis to trigger. Pb²⁺ and Hg²⁺ toxicity mediates apoptosis by increased reactive oxygen species (ROS) and cytochrome c release from mitochondria. To discover the role of hPLSCR3 in heavy metal toxicity, hPLSCR3 was overexpressed as a recombinant protein in Escherichia coli Rosetta (DE3) and purified by affinity chromatography. The biochemical assay using synthetic proteoliposomes demonstrated that hPLSCR3 translocated aminophospholipids in the presence of micromolar concentrations of Pb²⁺ and Hg²⁺. A point mutation in the Ca²⁺-binding motif (F258V) led to a ∼60% loss in the functional activity and decreased binding affinities for Pb²⁺ and Hg²⁺ implying that the divalent heavy metal ions bind to the Ca²⁺-binding motif. This was further affirmed by the characteristic spectra observed with stains-all dye. The conformational changes upon heavy metal binding were monitored by circular dichroism, intrinsic tryptophan fluorescence, and light-scattering studies. Our results revealed that Pb²⁺ and Hg²⁺ bind to hPLSCR3 with higher affinity than Ca²⁺ thus mediating scramblase activity. To summarize, this is the first biochemical evidence for heavy metals binding to the mitochondrial membrane protein leading to bidirectional translocation of PLs specifically toward phosphatidylethanolamine.

Hepatoprotective effects of zinc (II) via cytochrome P-450/reactive oxygen species and canonical apoptosis pathways after arsenite waterborne exposure in common carp

Chronic arsenicosis has threatened the survival of aquatic animals with molecular mechanisms yet clear. In the present study, liver damage was evident by fluctuated activities of transaminases and declined ATPases in common carp under arsenic (As) exposure for 30 days. Mechanically, As significantly decreased cytochrome P-1A (CYP1A) activity and increased reactive oxygen species (ROS) content, which corroborated mitochondrial dysfunction in the hepatocytes. This hypothesis was further suggested by Caspase-3-executed apoptosis by death receptor pathway (Fas, TNF-α and Caspase-8) and mitochondrial pathway (Bax, Bcl-2 and Caspase-9). The above results indicated that As-elicited oxidative damage lead to apoptotic hepatic injury in carp. On the contrary, zinc (Zn) exerted an ROS scavenger and an antidote to As in the present model evidenced by alleviated liver injury and restored liver function index. Moreover, Zn and As co-administration displayed partially recovered CYPs enzyme system and quenched apoptotic positive cells compared As treated alone. These outcomes could be applied to develop counter practices based on Zn preparations to decrease the biotoxicity of As.

Lead poisoning due to ingestion of lead-contaminated opium: A diagnostic study on patients' imaging findings

OBJECTIVES

Our study attempts to determine if for patients following ingestion of lead-contaminated opium, radiographs [plain X-ray (KUB)] or unenhanced computed tomography (CT scan) of the abdomen may be predictive of lead poisoning.

METHODS

Our study is concerned with patients of >21 years with elevated lead concentrations, who had undergone KUB or CT. Patients with other toxicities who had undergone similar imaging profiles but who had low blood lead level (BLL) were enrolled as controls.

RESULTS

We evaluated a total of 79 cases and 79 controls with median [IQR] BLLs of 126 [97.4, 160] μg/dL and 8.7 [5.5, 15] μg/dL. All cases and eleven controls (13.9%) were addicted to oral opium, and of these cases, anemia (94.9%) and abdominal pain (92.4%) were the two most common clinical manifestations. Two radiologists reviewed the X-ray and non-contrast CTs. Fifty (63.3%) and 53 (67.1%) cases and controls underwent CT scanning with 34 (68%) vs. 6 (11.3%) positive CTs (P < 0.001) while 43 (54.4%) and 39 (43.3%) underwent X-rays with 21 (48.8%) vs. 4 (11.8%) positive X-rays, respectively (P < 0.001). Positive CT is associated with BLL between 10 and 45 μg/dL with a specificity of 96.9%, 88.7% and positive predictive value of 97.5% and 85% respectively.

CONCLUSIONS

In suspected cases of lead exposure due to ingested opium, and if BLL is not readily available, a positive imaging result may guide radiologists and physicians to consider lead poisoning.

Zebrafish neurobehavioral phenomics applied as the behavioral warning methods for fingerprinting endocrine disrupting effect by lead exposure at environmentally relevant level

Environmental lead (Pb) exposure is a great hazard to the public health. Although environmentally relevant Pb poisoning is preventable, insidious Pb contaminants are still a major threat to human health. Herein, we reported that exposure to Pb at environmentally relevant concentration level (1 μg/L, 10 μg/L and 100 μg/L), disturbed the courtship behavior of adult male zebrafish and further altered the transcriptional patterns of key genes involved in testicular steroidogenesis (igf3, amh, piwil1, lhcgr, fshr, cyp11c1, star, cyp19a1a, cyp19a1b) and apoptosis (bax, cytoC, caspase 9, caspase 3, puma). Both the behavioral and the transcriptional profiles share a similar biphasic dose response, with stimulatory effects after low-level exposure and inhibitory effects after high-level exposure. This results revealed the endocrine disrupting effects of Pb even at an environmentally relevant level within the concentration range of ambient water quality criteria (AWQC) and the reliability of locomotion fingerprint as the indicator for detecting the risk induced by Pb pollution. Current research, for the first time, employed the ZebraTower system as the biological early warning system (BEWS) to find that Pb exerted biphasic effects on the courtship behavior and endocrine regulation of male adult zebrafish. Methodologically, we firstly propose an efficient solution to monitor and assess the risk of Pb exposure by combining the (BEWS) and data analyzing methods such as zebrafish phenomics, which would make a contribution to the detection and prevention of environmentally relevant Pb poisoning.

Combination therapy with vitamin C and DMSA for arsenic-fluoride co-exposure in rats

INTRODUCTION

Arsenic and fluoride are recognized globally as the most serious inorganic contaminants in drinking water. As there is no safe and effective treatment for the cases of fluoride poisoning and combined arsenic-fluoride toxicity, the present study was planned to assess (i) the mechanism of combined exposure to arsenic and fluoride via biochemical and spectroscopic data; (ii) the effect of a thiol chelating agent, meso-2,3-dimercaptosuccinic acid (DMSA), either individually or in combination with the antioxidant vitamin C in reversing arsenic-fluoride toxicity; and (iii) whether combination therapy enhances arsenic and fluoride removal from blood and soft tissues.

METHODS

Rats were exposed to arsenic (50 mg l-1) and fluoride (50 mg l-1) individually and in combination for 9 months and later administered DMSA (50 mg kg-1) via an i.p. route and vitamin C (25 mg kg-1) orally for 5 days. Biochemical parameters suggestive of alterations in the heme synthesis pathway, oxidative stress in blood, the liver and the kidneys, and concentrations of arsenic and fluoride in blood and soft tissues were studied. We also studied the infrared (IR) spectra of DNA extracted from the livers and kidneys of the normal and exposed animals.

RESULTS

It was found that chronic arsenic and fluoride exposure led to an increased oxidative stress condition and impaired heme synthesis (67% inhibition in δ-aminolevulinic acid dehydratase activity and 38% increase in δ-aminolevulinic acid synthetase activity). The decreased antioxidant defense mechanism was marked by a 2.25 fold increased concentration of Reactive Oxygen Species (ROS) and a 28% decrease in the Glutathione (GSH) level. Interestingly, concomitant exposure to arsenic and fluoride did not lead to antagonistic effects as the toxic effects were the same as those seen during the individual exposure to both the toxicants. It suggests that toxicity depends on the dose and duration of exposure. Combination therapy with DMSA and vitamin C showed a better efficacy than monotherapy in terms of reducing the arsenic and fluoride burden (more than 70% in blood and soft tissues) as well as reversal in the altered biochemical variables indicative of oxidative stress and tissue damage (80-85%). The infrared (IR) spectra of DNA isolated from the liver and kidneys suggested that the treatment with vitamin C and DMSA had no beneficial effects in terms of reversing DNA damage.

CONCLUSION

On the basis of the above observations, we suggest that the combinational therapy of DMSA and vitamin C would be more effective in arsenic and/or fluoride toxicity; however, more detailed studies are required to address recoveries in DNA damage.

Heavy metal toxicity: An update of chelating therapeutic strategies

AIM

This review illustrates heavy metals toxicity, currently available therapies and the role and efficacy of chelation therapy for its management.

SUMMARY

Heavy metals are necessary for various biological processes, but they become harmful in excess. Specifically, they induce oxidative stress by generating free radicals and reducing antioxidant levels. Heavy metals also alter the confirmation of protein and DNA and inhibit their function. Chelation therapy is commonly used to treat metals toxicity. Chelation is a chemical process that occurs when interaction between a central metal atom/ion and ligand leads to formation of a complex ring-like structure. The ligand has a donor ion/molecule, which has a lone pair of electrons and may be monodentate to polydentate. Each metal has a different reactivity with a ligand, so a specific chelation agent is required for each metal. Combination therapy with a chelating agent and an antioxidant led to improved outcome.

CONCLUSION

Heavy metal poisoning is a common health problem because of mining, smelting, industrial, agricultural and sewage waste. Heavy metals can be efficiently excreted from the body following treatment with proper chelation agents.

Probabilistic health risk assessment of heavy metals in honey, Manihot esculenta, and Vernonia amygdalina consumed in Enugu State, Nigeria

Honey is a nutritive fluid product of bees with an array of pharmacological/medicinal effects. As a natural product from honeybees, honey is regarded to be safe and free from any contaminants. Cassava tuber (Manihot esculenta)-based meal, Vernonia amygdalina (bitter leaf soup), and honey are common local cuisine in Nigeria. This is a human health risk assessment of heavy metals associated with the consumption of honey (Apis mellifera scutellata), cassava (Manihot esculenta), and bitter leaf (Vernonia amygdalina) in Enugu State, Nigeria. Concentrations of lead (Pb), Cd, As, Cu, Ni, Mn, Fe, Cr, and Fe in honey, soil, Manihot esculenta, and Vernonia amygdalina were determined using an atomic absorption spectrophotometer (AAS). The principal component analysis (PCA) was performed as a factor reduction technique among 12 factors (3 locations against 4 sources of heavy metals). The mean concentration of metals in honey, soil, Manihot esculenta, and Vernonia amygdalina ranged from 0.001 to 4.28 mg kg^-1, from 0.0026 to 170.52 mg kg^-1, from 0.012 to 80.63 mg kg^-1, and from 0.0016 to 126.48 mg kg^-1, respectively. Pb showed the highest carcinogenic risk with values of 3.18E-04-1.43E-01 in Vernonia amygdalina and 1.69E-04-3.47E-04 in Manihot esculenta for adults and children, respectively. In honey, Cd showed the highest carcinogenic risk with values of 1.26E-02-1.07E-01. About 51.5% of total cancer risk (TCR) was below 1E-04. Consumption of honey, Vernonia amygdalina, and Manihot esculenta in some urban parts of Enugu may pose some adverse health effects.

Consuming Blackberry as a Traditional Nutraceutical Resource from an Area with High Anthropogenic Impact

The most serious quality issue of natural resources for human consumption or medicinal purposes is the contamination with pollutants harmful to consumers. Common blackberry (Rubus fruticosus L.) is a sought-after nutraceutical and an important component in herbal medicine in many places around the globe. The present study aims to analyze the level of heavy metal bioaccumulation in blackberry organs, as well as its spatial distribution in two consecutive years immediately after the interruption of the extended activity of the industrial source of pollution. The research was conducted in one of the most polluted areas in Romania and Eastern Europe, within a 26 km radius of the source of pollution. The Pb, Cd, Cu, and Zn concentrations in the leaves, flowers, and unwashed blackberry fruits were analyzed spectrophotometrically through flame atomic absorption spectroscopy (FAAS). The results show that blackberry is an important bioaccumulator of these heavy metals—71% of the Pb concentration values and 100% of the Cd concentration values exceeded the World Health Organization thresholds by up to 29 and 15 times, respectively. Also, the leaves are the largest reservoirs of Pb and Zn (the median values: 51.4 mg/kg dry weight and 105.2 mg/kg d.w., respectively), and the flowers contained the largest quantities of Cd and Cu (2.54 mg/kg d.w. and 11.3 mg/kg d.w., respectively). The Pb concentrations decreased by a power function in relation to the distance from the source of pollution. The implications of these results on the safety of the use of blackberry are discussed. The urgent necessity for food education of the local population which consumes contaminated nutraceutical products is emphasized.