Heavy metal chelation in neurotoxic exposures

Phytochemical: a treatment option for heavy metal induced neurotoxicity

Heavy metals are known to be carcinogenic, mutagenic, and teratogenic. Some heavy metals are necessary while present in the growing medium in moderate concentrations known to be essential heavy metals as they required for the body functioning as a nutrient. But there are some unwanted metals and are also toxic to the environment and create a harmful impact on the body, which termed to be non-essential heavy metals. Upon exposure, the heavy metals decrease the major antioxidants of cells and enzymes with the thiol group and affect cell division, proliferation, and apoptosis. It interacts with the DNA repair mechanism and initiates the production of reactive oxygen species (ROS). It subsequently binds to the mitochondria and may inhibit respiratory and oxidative phosphorylation in even low concentrations. This mechanism leads to damage antioxidant repair mechanism of neuronal cells and turns into neurotoxicity. Now, phytochemicals have led to good practices in the health system. Phytochemicals that are present in the fruits and herbs can preserve upon free radical damage. Thus, this review paper summarized various phytochemicals which can be utilized as a treatment option to reverse the effect of the toxicity caused by the ingestion of heavy metals in our body through various environmental or lifestyles ways.

Exposure of metal toxicity in Alzheimer’s disease: An extensive review

Metals serve important roles in the human body, including the maintenance of cell structure and the regulation of gene expression, the antioxidant response, and neurotransmission. High metal uptake in the nervous system is harmful because it can cause oxidative stress, disrupt mitochondrial function, and impair the activity of various enzymes. Metal accumulation can cause lifelong deterioration, including severe neurological problems. There is a strong association between accidental metal exposure and various neurodegenerative disorders, including Alzheimer’s disease (AD), the most common form of dementia that causes degeneration in the aged. Chronic exposure to various metals is a well-known environmental risk factor that has become more widespread due to the rapid pace at which human activities are releasing large amounts of metals into the environment. Consequently, humans are exposed to both biometals and heavy metals, affecting metal homeostasis at molecular and biological levels. This review highlights how these metals affect brain physiology and immunity and their roles in creating harmful proteins such as β-amyloid and tau in AD. In addition, we address findings that confirm the disruption of immune-related pathways as a significant toxicity mechanism through which metals may contribute to AD.

Protective Effect of Wheat and Barley Grass Against the Acute Toxicological Effects of the Concurrent Administration of Excessive Heavy Metals in Drinking Water on the Rats Liver and Brain

Heavy metal contaminated water is a great concern because of its high toxiciy, non-biodegradability, and bioaccumulation. Therefore, non-contaminated water is fundamental for a healthy life. Special attention is paid to the health-promoting ingredients of germinated whole cereal products. This study aimed to (1) examine the potentially harmful effects of Cu, Mn, and Zn on rat livers and brains, and (2) the potentially protective action of wheat and barley grasses against the expected harmful effects of these metals. The rats were treated with water contaminated by heavy metals (HMs) and germinated wheat and barley for 60 days. The rat liver functions and histopathological examinations were analyzed. Comet assay was evaluated to assess the damage in the DNA of rat livers and brains. The results indicated a significant alteration in liver functions in rats exposed to HMs; however, wheat and barley grasses at high doses decreased the harmful effects. An insignificant difference was noticed in total protein, albumin, and globulin of rats treated with HMs compared with the control. A significant increase in the serum and liver levels of HMs was recorded; however, they were reduced by wheat and barley grasses. Rat livers treated with HMs exhibited severe histological effects. The groups treated with wheat and barley grasses showed a normal liver architecture. A significant increase in DNA damage in the livers and brains was observed in rats treated with HMs, which was reduced when treated with wheat and barley grasses. Thus, using germinated seeds is promising to avoid damaging of HMs.

A common theme for axonopathies? The dependency cycle of local axon homeostasis

The number of acquired or inherited conditions leading to axon degeneration (from now on referred to as axonopathies) is vast. To diagnose patients, clinicians use a range of indicators including physiology, morphology, family and patient history, as well as genetics, with the specific location of the lesion within the nervous system being a prominent feature. For the neurobiologist, these criteria are often unsatisfactory, and key questions remain unanswered. For example, does it make sense that different axonopathies affect distinct neuron groups through distinct mechanisms? Would it not be more likely that there are common routes to axon degeneration? In this opinion piece, I shall pose this fundamental question and try to find answers that are hopefully thought-provoking and trigger some conceptual rethinking in the field. I will conclude by describing the 'dependency cycle of axon homeostasis' as a new approach to make sense of the intricate connections of axon biology and physiology, also suggesting that different axonopathies might share common paths to axon degeneration.

Mercury Chloride but Not Lead Acetate Causes Apoptotic Cell Death in Human Lung Fibroblast MRC5 Cells via Regulation of Cell Cycle Progression

Heavy metals are important for various biological systems, but, in excess, they pose a serious risk to human health. Heavy metals are commonly used in consumer and industrial products. Despite the increasing evidence on the adverse effects of heavy metals, the detailed mechanisms underlying their action on lung cancer progression are still poorly understood. In the present study, we investigated whether heavy metals (mercury chloride and lead acetate) affect cell viability, cell cycle, and apoptotic cell death in human lung fibroblast MRC5 cells. The results showed that mercury chloride arrested the sub-G₁ and G₂/M phases by inducing cyclin B1 expression. In addition, the exposure to mercury chloride increased apoptosis through the activation of caspase-3. However, lead had no cytotoxic effects on human lung fibroblast MRC5 cells at low concentration. These findings demonstrated that mercury chloride affects the cytotoxicity of MRC5 cells by increasing cell cycle progression and apoptotic cell death.

Unsafe herbal sex enhancement supplements in Nigerian markets: a human risk assessment

High rates of irreversible oligo- or azoospermia are found among Nigerian men, leading many to consume herbal male sex enhancement products. The possibility of reproductive toxicity due to heavy metal contamination (Cr, As, Co, Hg, Cd, and Pb) of herbal products commonly used to boost libido or treat erectile dysfunction necessitated this study. In this study, herbal sex enhancement supplements were bought from pharmaceutical shops in Port Harcourt, Nigeria, and analyzed for heavy metals (Cr, As, Co, Hg, Cd, and Pb) contents using atomic absorption spectroscopy. The estimated daily metal intake (EDImetal), target hazard quotients (THQ), and total target hazard quotients (TTHQ) were determined. All the herbal sex enhancers used in this study contained heavy metals in these ranges: lead (0.032-0593), cobalt (0.025-0.075), cadmium (0.0011-0.048), and chromium (0.016-0.49) mg/kg. About 24.32% of the samples had TTHQ greater than 1. The EDImetal, THQ, and TTHQ of herbal sex enhancement supplements suggest that the use of some of these herbal sex enhancement supplements may not be risk-free after chronic exposure. Herbal sex enhancement supplements sold in Nigeria contain high levels of lead and cadmium. Since these metals are known to have male reproductive toxicity, these supplements may be adding to both the body burden of these metals and also implicated in the increasing incidence of male infertility in Nigeria.

Metals and Neurodegeneration

Metals play important roles in the human body, maintaining cell structure and regulating gene expression, neurotransmission, and antioxidant response, to name a few. However, excessive metal accumulation in the nervous system may be toxic, inducing oxidative stress, disrupting mitochondrial function, and impairing the activity of numerous enzymes. Damage caused by metal accumulation may result in permanent injuries, including severe neurological disorders. Epidemiological and clinical studies have shown a strong correlation between aberrant metal exposure and a number of neurological diseases, including Alzheimer’s disease, amyotrophic lateral sclerosis, autism spectrum disorders, Guillain–Barré disease, Gulf War syndrome, Huntington’s disease, multiple sclerosis, Parkinson’s disease, and Wilson’s disease. Here, we briefly survey the literature relating to the role of metals in neurodegeneration.

Detection of Ni, Cd, and Cu in green leafy vegetables collected from different cultivation areas in and around Colombo District, Sri Lanka

Five types of green leafy vegetables ["Kankun" (Ipomoea aquatica), "Mukunuwenna" (Alternanthera sessilis), "Thampala" (Amaranthus viridis), "Nivithi" (Basella alba), and "Kohila leaves" (Lasia spinosa)] were randomly collected from six different locations (Wellampitiya, Kolonnawa, Kottawa, Piliyandala, Bandaragama, and Kahathuduwa) in and around Colombo District, Sri Lanka, and subjected to analysis of three heavy metals [nickel (Ni), cadmium (Cd), and copper (Cu)] by atomic absorption spectrometry. Soils from green leafy vegetable cultivation lands and irrigated water were also tested. The average concentrations of heavy metals Ni, Cd, and Cu in soils were 51.5 ± 45.5, 1.4 ± 1.1, and 66.5 ± 59.5 mg kg(-1), respectively. The highest Ni contamination was detected in the irrigated water samples from Wellampitiya (2.02 mg L(-1)) followed by Kolonnawa (1.02 mg L(-1)) and Kahathuduwa (0.25 mg L(-1)) areas. This has exceeded the WHO/FAO guideline (0.2 mg L(-1)). However, Cd and Cu contents in all tested irrigated water samples were well below the detection limits. Significant differences were observed in Ni, Cd, and Cu levels, between both production sites and green leafy vegetables analyzed (P < 0.05). The mean concentrations (mg kg(-1), dry weight basis) of heavy metals in all green leafy vegetable samples collected from six areas varied as 0.23 ± 0.15 for Cd, 12.60 ± 9.01 for Cu, and 7.62 ± 8.41 for Ni. Maximum Ni, Cd, and Cu contaminations were found in the green leafy vegetables collected from Kolonnawa area. Among the green leafy vegetables analyzed, "Kohila leaves" have the highest tendency to accumulate Ni, Cd, and Cu from the environment.

Peripheral neuropathy due to vitamin deficiency, toxins, and medications

PURPOSE OF REVIEW

Peripheral neuropathies secondary to vitamin deficiencies, medications, or toxins are frequently considered but can be difficult to definitively diagnose. Accurate diagnosis is important since these conditions are often treatable and preventable. This article reviews the key features of different types of neuropathies caused by these etiologies and provides a comprehensive list of specific agents that must be kept in mind.

RECENT FINDINGS

While most agents that cause peripheral neuropathy have been known for years, newly developed medications that cause peripheral neuropathy are discussed.

SUMMARY

Peripheral nerves are susceptible to damage by a wide array of toxins, medications, and vitamin deficiencies. It is important to consider these etiologies when approaching patients with a variety of neuropathic presentations; additionally, etiologic clues may be provided by other systemic symptoms. While length-dependent sensorimotor axonal peripheral neuropathy is the most common presentation, several examples present in a subacute severe fashion, mimicking Guillain-Barré syndrome.

Toxic metals signature in the human seminal plasma of Pakistani population and their potential role in male infertility

Aims of this study were to provide firsthand data on the incidence of trace metals in human seminal plasma and find possible correlations between levels of toxic metals and semen quality of Pakistani population. Human semen samples were collected from male partners of couples undergoing infertility assessment at the National Institute of Health Islamabad (Pakistan). We investigated seventy-five seminal plasma samples, which were further categorized into three groups (normozoospermia, oligozoospermia and azoospermia) according to WHO guidelines. The concentration of 17 different toxic metals in human seminal plasma was determined simultaneously by using Inductively coupled plasma mass spectrometry (ICP-MS). Out of 17 trace metals, Cd and Ni showed significant difference (p < 0.05) among three monitored groups. Ni and Cd concentrations in the seminal plasma were negatively correlated with sperm concentration (r = -0.26, -0.29) and motility (r = -0.33, -0.37), respectively. This study suggested that exposure of Ni and Cd is mainly related with the consumption of contaminated dietary items, including ghee (cooking oil), flour and other agri-products. In some semen samples, the concentrations of Sn, V, Cu, Pb, Cr and Hg exhibited high levels suggesting a recent human exposure to surrounding sources. In Pakistani human semen samples, the levels of trace metals were lower and/or comparable to that found in populations of other countries. The results show the first evidence of the effect of toxic metals on semen quality and male infertility in Pakistan.

The risk of lead contamination in bone broth diets

The preparation and consumption of bone broth is being increasingly recommended to patients, for example as part of the gut and psychology syndrome (GAPS) diet for autism, attention-deficit hyperactivity disorder, dyslexia, dyspraxia, depression and schizophrenia, and as part of the paleolithic diet. However, bones are known to sequester the heavy metal lead, contamination with which is widespread throughout the modern environment. Such sequestered lead can then be mobilised from the bones. We therefore hypothesised that bone broth might carry a risk of being contaminated with lead. A small, blinded, controlled study of lead concentrations in three different types of organic chicken broth showed that such broths do indeed contain several times the lead concentration of the water with which the broth is made. In particular, broth made from skin and cartilage taken off the bone once the chicken had been cooked with the bones in situ, and chicken-bone broth, were both found to have markedly high lead concentrations, of 9.5 and 7.01 μg L(-1), respectively (compared with a control value for tap water treated in the same way of 0.89 μg L(-1)). In view of the dangers of lead consumption to the human body, we recommend that doctors and nutritionists take the risk of lead contamination into consideration when advising patients about bone broth diets.

Metals, oxidative stress and neurodegeneration: a focus on iron, manganese and mercury

Essential metals are crucial for the maintenance of cell homeostasis. Among the 23 elements that have known physiological functions in humans, 12 are metals, including iron (Fe) and manganese (Mn). Nevertheless, excessive exposure to these metals may lead to pathological conditions, including neurodegeneration. Similarly, exposure to metals that do not have known biological functions, such as mercury (Hg), also present great health concerns. This review focuses on the neurodegenerative mechanisms and effects of Fe, Mn and Hg. Oxidative stress (OS), particularly in mitochondria, is a common feature of Fe, Mn and Hg toxicity. However, the primary molecular targets triggering OS are distinct. Free cationic iron is a potent pro-oxidant and can initiate a set of reactions that form extremely reactive products, such as OH. Mn can oxidize dopamine (DA), generating reactive species and also affect mitochondrial function, leading to accumulation of metabolites and culminating with OS. Cationic Hg forms have strong affinity for nucleophiles, such as -SH and -SeH. Therefore, they target critical thiol- and selenol-molecules with antioxidant properties. Finally, we address the main sources of exposure to these metals, their transport mechanisms into the brain, and therapeutic modalities to mitigate their neurotoxic effects.

Oxidative stress and metal carcinogenesis

Occupational and environmental exposures to metals are closely associated with an increased risk of various cancers. Although carcinogenesis caused by metals has been intensively investigated, the exact mechanisms of action are still unclear. Accumulating evidence indicates that reactive oxygen species (ROS) generated by metals play important roles in the etiology of degenerative and chronic diseases. This review covers recent advances in (1) metal-induced generation of ROS and the related mechanisms; (2) the relationship between metal-mediated ROS generation and carcinogenesis; and (3) the signaling proteins involved in metal-induced carcinogenesis, especially intracellular reduction-oxidation-sensitive molecules.