Lead-induced oxidative stress adversely affects health of the occupational workers

The combined analysis of transcriptomics and metabolomics reveals the mechanisms by which dietary quercetin regulates growth and immunity in Penaeus vannamei

As a potent antioxidant, the flavonoid compound quercetin (QUE) has been widely used in the farming of aquatic animals. However, there are fewer reports of the beneficial effects, especially in improving immunity of Penaeus vannamei by QUE. The aim of this study was to investigate the effects of dietary QUE on growth, apoptosis, antioxidant and immunity of P. vannamei. It also explored the potential mechanisms of QUE in improving the growth and immunity of P. vannamei. P. vannamei were fed diets with QUE for 60 days. The results revealed that QUE (0.5 or 1.0 g/kg) ameliorated the growth, and the expressions of genes related to apoptosis, antioxidant, and immunity. The differentially expressed genes (DEGs) and differential metabolites (DMs) obtained through transcriptomics and metabolomics, respectively, enriched in pathways related to nutritional metabolism such as lipid metabolism, amino acid metabolism, and carbohydrate metabolism. After QUE addition, especially at 0.5 g/kg, DEGs were enriched into the functions of response to stimulus and antioxidant activity, and the pathways of HIF-1 signaling pathway, C-type lectin receptor signaling pathway, Toll-like receptor signaling pathway, and FoxO signaling pathway. In conclusion, dietary QUE can ameliorate growth, apoptosis, antioxidant and immunity of P. vannamei, the appropriate addition amount was 0.5 g/kg rather than 1.0 g/kg. Regulations of QUE on nutrient metabolism and immune-related pathways, and bioactive metabolites, were important factors for improving the aforementioned abilities in P. vannamei.

Mediating role of systemic inflammation in the association between heavy metals exposure and periodontitis risk

BACKGROUND

This study evaluated the mediating role of systemic inflammation in the association between exposure to heavy metals and periodontitis in a nationwide sample of adults.

METHODS

Pooled cross-sectional data from the National Health and Nutrition Examination Survey (NHANES 2009-2014) were used (n = 8993). Periodontitis was defined by a full-mouth examination and classified as no/mild and moderate/severe (mod/sev) groups. Blood and urinary heavy metal levels were investigated, including cadmium (Cd), lead (Pb), and mercury (Hg). In addition, systemic inflammation was assessed using circulatory leukocyte counts and C-reactive protein (CRP) levels.

RESULTS

Multivariable logistic regression analysis revealed the positive associations of blood and urinary levels of Cd and Pb with mod/sev periodontitis. In contrast,blood Hg levels did not show a significant association. The odds of having periodontitis were 1.233 and 1.311 times higher for each one-unit increment in Ln-transformed blood Cd (95% confidence interval [CI]: 1.109-1.371) and Pb (95% CI: 1.170-1.470), respectively. Mediation analysis suggested a 6.3% to 11.5% contribution of leucocyte counts in the association of blood Cd and Pb levels with periodontitis. Sensitivity analyses for urinary Cd levels yielded consistent mediating effects. However, no significant mediating effect of CRP was detected.

CONCLUSION

Higher exposures to Cd and Pb were positively associated with periodontitis risk. These associations might be partially mediated by the elevated levels of leukocytes rather than CRP. Further longitudinal studies are needed to elucidate the discordant results of the systemic inflammatory biomarkers.

Protective Effect of Protocatechuic Acid on Oxidative Damage and Cognitive Impairment in Pb-Induced Rats

Protocatechuic acid (PCA), a class of water-soluble phenolic acid abundant in the human diet, has been shown to be of great nutritional interest and to have medicinal value. However, the protective effects against lead (Pb)-induced body injury have not been elucidated. In this study, we explored the protective effect of PCA on Pb-induced oxidative damage and cognitive impairment in rats. The results showed that PCA could reduce the Pb content in rat bodies (blood, bone, brain, liver, and kidney) after Pb exposure. Moreover, PCA may inhibit Pb-induced oxidative damage by increasing the activity of antioxidant enzymes such as superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) and decreasing the level of malondialdehyde (MDA) in the brain, liver, and kidney. In addition, PCA may alleviate Pb-induced learning and memory impairment by upregulating neurotransmitter levels; maintaining the normal function of N-methyl-D-aspartate receptors (NMDARs); and promoting Ca2+ influx, thus activating signaling molecules, related protein kinases, and transcription factors in the cAMP-PKA-CREB pathway. In general, PCA could reduce oxidative stress and ameliorate the learning and memory deficits in Pb-treated rats, indicating that PCA may be an effective preventive agent and treatment or plumbism.

Renal tubular dysfunction in greenhouse farmers exposed to pesticides unveiled by a panel of molecular biomarkers of kidney injury

Growing evidence suggests that chronic exposure to pesticides may cause adverse effects on the health of the exposed population leading to organ-specific toxicity, including kidney damage. Traditional markers used to assess renal function (glomerular filtration rate (GFR), and serum creatinine and cystatin C -Cys-C-) are inadequate to evaluate a potential subclinical renal impairment linked to occupational exposure to pesticides, since levels above the upper limit of normal only occur when renal damage is very extensive. The use of more sensitive biomarkers is therefore needed. This study investigated novel urinary biomarkers of kidney function (microalbuminuria, osteopontin (OPN), trefoil factor 3 (TFF3), β-2-microglobulin, neutrophil gelatinase-associated lipocalin (NGAL), and Cys-C), together with the aforementioned traditional serum biomarkers, to assess potential kidney damage in farmers exposed to pesticides in an intensive agriculture setting. The study population consisted of 175 greenhouse workers and 91 healthy control subjects from Almeria (Southeastern Spain), a major hub of greenhouse agriculture. Data were collected at two different time-points of the same crop season: a period with greater pesticide use (high exposure period) and another with lower pesticide use (low exposure period). Significantly higher urinary levels of OPN and TFF3 were found in greenhouse workers than in controls, and in the high pesticide exposure period compared to that of low exposure. These changes suggest a subclinical tubular damage linked to pesticide exposure. In contrast, microalbuminuria, GFR, serum creatinine and Cys-C failed to be associated with pesticide exposure, suggesting that glomerular function was spared. Increased OPN and TFF3 levels over time may suggest a gradual progression from tubular dysfunction to chronic kidney disease in the exposed population.

Unravelling blood-based epigenetic mechanisms: the impact of hsa-miR-146a and histone H3 acetylation in lead-induced inflammation among occupational workers

BACKGROUND

Occupational and environmental exposure to lead (Pb) is a persistent health problem majorly in developing countries and has been implied to cause epigenetic alterations. Its effect on histone post-translational modifications is not explored in human population. MicroRNAs are epigenetic modulators reported to be differentially expressed under Pb exposure. The present study was targeted to find plausible association between the role of hsa-miR-146a and global histone (H3) acetylation in Pb-induced inflammation in occupationally exposed workers.

MATERIALS AND METHODS

A total of 100 occupationally exposed individuals working in different industries were recruited for the study and divided into 2 groups based on the median Pb levels [low Pb group (Pb < 5 μg/dL) and High Pb group (Pb > 5 μg/dL)]. The Pb levels were measured in whole blood using atomic absorption spectrometry to confirm Pb exposure. Histone H3 acetylation and serum interleukin-6 (IL-6) levels were measured using colorimetric methods and enzyme-linked immunosorbent assay (ELISA), respectively. MicroRNA-146a expression was quantified using TaqMan assay.

RESULTS

The median BLL of the study population was 5 μg/dL. BLL, IL-6, and Histone (H3) acetylation increased significantly with the duration of exposure. BLL level showed a significant positive correlation with IL-6 and histone H3 acetylation level. We also found that hsa-miR-146a exhibited significantly increased expression in the high Pb group compared to the low Pb group (Fold change: 2.56; P = 0.014). The linear regression model suggested that BLL has significantly predicted histone H3 acetylation, hsa-miR-146a, and IL-6 in the study subjects.

CONCLUSION

The finding that hsa-miR146a was significantly upregulated in individuals with high BLL and had a significant negative correlation with serum IL-6 suggests that Pb-induced oxidative stress likely activates H3 acetylation, which then releases inflammatory cytokines like IL-6.

Origin, dietary exposure, and toxicity of endocrine-disrupting food chemical contaminants: A comprehensive review

Endocrine-disrupting chemicals (EDCs) are a growing public health concern worldwide. Consumption of foodstuffs is currently thought to be one of the principal exposure routes to EDCs. However, alternative ways of human exposure are through inhalation of chemicals and dermal contact. These compounds in food products such as canned food, bottled water, dairy products, fish, meat, egg, and vegetables are a ubiquitous concern to the general population. Therefore, understanding EDCs' properties, such as origin, exposure, toxicological impact, and legal aspects are vital to control their release to the environment and food. The present paper provides an overview of the EDCs and their possible disrupting impact on the endocrine system and other organs.

Adaptive changes in redox response and decreased platelet aggregation in lead-exposed workers

Chronic lead exposure can generate pro-oxidative and pro-inflammatory conditions in the blood, related to high platelet activation and aggregation, altering cell functions. We studied ADP-stimulated aggregation and the oxidant/antioxidant system of platelets from chronically lead-exposed workers and non-exposed workers. Platelet aggregation was low in lead-exposed workers (62 vs. 97%), who had normal platelet counts and showed no clinical manifestations of hemostatic failure. ADP-activated platelets from lead-exposed workers failed to increase superoxide release (3.3 vs. 6.6 µmol/g protein), had low NADPH concentration (60 vs. 92 nmol/mg protein), high concentration of hydrogen peroxide (224 vs. 129 nmol/mg protein) and high plasma PGE₂ concentration (287 vs. 79 pg/mL). Altogether, those conditions, on the one hand, could account for the low platelet aggregation and, on the other, indicate an adaptive mechanism for the oxidative status of platelets and anti-aggregating molecules to prevent thrombotic problems in the pro-oxidant and pro-inflammatory environment of chronic lead exposure.

Potential diagnostic biomarkers for lead-induced hepatotoxicity and the role of synthetic chelators and bioactive compounds

Lead (Pb2+) poisoning is a public health concern of global dimensions. Although several public health guidelines and workplace safety policies are existing and enforced, lead toxicity cases are drastically increasing. Lead exposure leads to numerous harmful consequences and causes adverse effects on different body organs and systems, mainly via the generation of reactive oxygen species, leading to augmented oxidative stress, competing with metal ions, and binding with the sulfhydryl groups. In several instances, lead poisoning cases remain undiagnosed and untreated or receive only symptomatic treatment. Estimation of blood lead levels reflects only a recent exposure, however, which does not reveal the total body burden. This review summarizes the effects of lead with special reference to hepatotoxicity and some of the potential diagnostic biomarkers. Furthermore, it also focuses on synthetic chelators used in the treatment of lead poisoning and the advantage of using bioactive compounds with an emphasis on the ameliorative effect of garlic.

Clerodendrum viscosum leaves attenuate lead-induced neurotoxicity through upregulation of BDNF-Akt-Nrf2 pathway in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Clerodendrum viscosum is an important medicinal plant in Ayurveda in Bangladesh and its leaves are used as a remedy for various diseases such as anti-inflammatory, antibacterial, hyperglycemic, hepatoprotective effects.

AIM OF THE STUDY

The present study aimed to evaluate the protective effect of aqueous extract of C. viscosum leaves against Pb-induced neurobehavioral and biochemical changes in mice.

MATERIALS AND METHODS

Swiss albino mice were divided as a) control, b) lead treated (Pb) and c) C. viscosum leaves (Cle) d) Pb plus Cle groups. Pb-acetate (10 mg/kg body weight) was given to Pb and Pb + Cle groups mice, and water extract of leaves (50 mg/kg body weight) was provided as supplementation to Cle and Pb + Cle groups mice for 30 days. Elevated plus maze and Morris water maze tests were used for evaluating anxiety, spatial memory and learning, respectively. Status of cholinesterase, SOD, GSH enzyme activity and neurotoxicity markers such BDNF and Nrf2 levels were analyzed in the brain tissue of experimental mice.

RESULTS

Poorer learning, inferior spatial memory, and increased anxiety-like behavior in Pb-exposure mice were noted when compared to control mice in Morris water maze and elevated plus maze test, respectively. In addition, expression of BDNF and Nrf2, cholinesterase activity along with antioxidant activity were significantly reduced compared to control group (p < 0.01). Interestingly, C. viscosum leaves' aqueous extract supplementation in Pb-exposed mice provide a significant improved neurochemical and antioxidant properties through the augmentation of activity of cholinergic enzymes, and upregulation of BDNF and Nrf2 levels in the brain tissue compared to Pb-exposed mice.

CONCLUSIONS

This study suggested that C. viscosum leaves restore the cognitive dysfunction and reduce anxiety-like behavior through upregulation of BDNF mediated Akt-Nrf2 pathway in Pb-exposure mice.

High-density lipoprotein cholesterol modifies the association between blood lead and uric acid: results from NHANES 2005-2016

BACKGROUND

The association between blood lead (PbB) and uric acid (SUA) remains unclear in US adults without a high level of lead exposure. Additionally, the effects of high-density lipoprotein cholesterol (HDL-C) modifying this association are still unclear. Therefore, this study aims to assess the effect of modification of high-density lipoprotein cholesterol on the association between PbB and SUA.

METHOD

This research analyzed National Health and Nutrition Examination Survey (NHANES) data from 2005 to 2016. Through several screenings, 18,578 participants over the age of 20 were eligible for the analysis. Multivariable linear regression was used to evaluate the association between PbB and SUA. By having stratified participants based on the HDL-C intake category (low HDL-C intake < 50 mg/dl; high HDL-C intake ≥ 50 mg/dl), effect modification by HDL-C was assessed through a likelihood ratio test between PbB and SUA.

RESULT

Multivariable linear regression indicated that PbB positively affects SUA (β = 0.19, 95% CI 0.16-0.22). The relationship between PbB and SUA was different in the low and high HDL-C intake group (β 0.12 95% Cl 0.08-0.16 vs. β 0.26 95% Cl 0.22 ~ - 0.30). Furthermore, high-density lipoprotein cholesterol significantly modified the relationship between PbB and SUA in all models which indicates that the interaction of lead exposure and HDL-C is more dangerous than the sum of the individual effects.

CONCLUSIONS

Our study shows that high-density lipoprotein cholesterol and blood lead have an interactive effect on increasing uric acid, which may have great importance for clinical medication.

The health effects of low blood lead level in oxidative stress as a marker, serum gamma-glutamyl transpeptidase level, in male steelworkers

Background

This study aimed to investigate the association between lead exposure and serum gamma-glutamyl transpeptidase (γGT) levels as an oxidative stress marker in male steelworkers.

Methods

Data were collected during the annual health examination of workers in 2020. A total of 1,654 steelworkers were selected, and the variables for adjustment included the workers' general characteristics, lifestyle, and occupational characteristics. The association between the blood lead level (BLL) and serum γGT level was investigated by multiple linear and logistic regression analyses. The BLL and serum γGT values that were transformed into natural logarithms were used in multiple linear regression analysis, and the tertile of BLL was used in logistic regression analysis.

Results

The geometric mean of the participants' BLLs and serum γGT level was 1.36 μg/dL and 27.72 IU/L, respectively. Their BLLs differed depending on age, body mass index (BMI), smoking status, drinking status, shift work, and working period, while their serum γGT levels differed depending on age, BMI, smoking status, drinking status, physical activity, and working period. In multiple linear regression analysis, the difference in models 1, 2, and 3 was significant, obtaining 0.326, 0.176, and 0.172 (all: p < 0.001), respectively. In the multiple linear regression analysis stratified according to drinking status, BMI, and age, BLLs were positively associated with serum γGT levels. Regarding the logistic regression analysis, the odds ratio of the third BLL tertile in models 1, 2, and 3 (for having an elevated serum γGT level within the first tertile reference) was 2.74, 1.83, and 1.81, respectively.

Conclusions

BLL was positively associated with serum γGT levels in male steelworkers even at low lead concentrations (< 5 μg/dL).

Role of Ape1 in Impaired DNA Repair Capacity in Battery Recycling Plant Workers Exposed to Lead

Exposure to lead in environmental and occupational settings continues to be a serious public health problem. At environmentally relevant doses, two mechanisms may underlie lead exposition-induced genotoxicity, disruption of the redox balance and an interference with DNA repair systems. The aim of the study was to evaluate the ability of lead exposition to induce impaired function of Ape1 and its impact on DNA repair capacity of workers chronically exposed to lead in a battery recycling plant. Our study included 53 participants, 37 lead exposed workers and 16 non-lead exposed workers. Lead intoxication was characterized by high blood lead concentration, high lipid peroxidation and low activity of delta-aminolevulinic acid dehydratase (δ-ALAD). Relevantly, we found a loss of DNA repair capacity related with down-regulation of a set of specific DNA repair genes, showing specifically, for the first time, the role of Ape1 down regulation at transcriptional and protein levels in workers exposed to lead. Additionally, using a functional assay we found an impaired function of Ape1 that correlates with high blood lead concentration and lipid peroxidation. Taken together, these data suggest that occupational exposure to lead could decrease DNA repair capacity, inhibiting the function of Ape1, as well other repair genes through the regulation of the ZF-transcription factor, promoting the genomic instability.

Comparative efficacy of silibinin and nano-silibinin on lead poisoning in Male Wistar rats

Lead (Pb) is an environmental neurotoxin that can lead to toxicity. It has shown that tissues can be exposed to oxidative stress in lead poisoning. Since silymarin is a natural agent with antioxidant effects, this study aimed to investigate the antioxidant and chelation effects of silibinin and nano-silibinin on the oxidative stress status in lead-poisoned rats. Sixty male Wistar rats randomly divided into ten groups (n = 6). Control and Pb groups treated with or without silibinin and nano-silibinin for six days. Following measuring of weight and blood lead levels, biochemical antioxidant parameters evaluated. Finally, a histopathological examination of the liver performed. In this experiment, silibinin and more efficiently nano-silibinin prevented weight loss and blood lead level elevation induced by lead. Also, they increased the attenuated levels of superoxide dismutase (SOD) activity, catalase (CAT), total thiol molecules (TTM), glutathione (GSH), and total antioxidant capacity (TAC). Lead-induced elevation of lipid peroxidation products (MDA) and nitric oxide (NO) normalized to the standard level in silibinin and especially nano-silibinin groups. These data suggested that silibinin and especially nano-silibinin can decrease blood lead levels and prevent weight loss and oxidative stress in the lead-poisoned rat's model.

Parental Lead Exposure Promotes Neurobehavioral Disorders and Hepatic Dysfunction in Mouse Offspring

Lead (Pb) induces neurotoxicity in both children and adults. Children are more vulnerable to Pb toxicity than adults. Little is known about the effects of Pb on the mental health of the children who are prenatally exposed. Therefore, we designed an animal experiment to compare the adverse effects of Pb on neurobehavioral and hepatic functions between Pb-exposed (Pb mice) and parental Pb-exposed (P-Pb mice) group mice. Mice were treated with Pb-acetate (10 mg/kg bodyweight/day) via drinking water. Male mice from unexposed parents treated with Pb for 90 days were defined as Pb mice, whereas male mice from Pb-exposed parents treated with Pb for further 90 days were defined as P-Pb mice. Anxiety-like behavior and spatial memory and learning were assessed by elevated plus maze and Morris water maze. Serum hepatic enzyme activities and butyrylcholinesterase activity were measured by an analyzer. P-Pb mice displayed increased anxiety-like behavior and memory and learning impairments compared to Pb mice. BChE activity was significantly decreased in P-Pb mice compared to Pb mice. Pb levels in the brains of P-Pb mice were significantly higher than those of Pb mice. The activities of serum hepatic enzymes of P-Pb mice were also higher than those of Pb mice. Additionally, histopathology data revealed that hepatic tissue injury was more pronounced in P-Pb mice than in Pb mice. Thus, the results suggest that persistent exposure to Pb from fetus to adult causes more severe neurobehavioral changes and hepatic toxicities than adult exposure only.

Association between occupational lead exposure and immunotoxicity markers: A systematic review and meta-analysis

Recent evidences suggest the role of chronic lead (Pb) exposure in altering immunological parameters. Present study aimed to systematically review existing literature and synthesize quantitative evidence on the association between chronic Pb exposure and changes in immunological markers. Observational studies reporting immunological markers such as leukocyte derivative counts (CD3⁺, CD4⁺, CD8⁺, CD45⁺, CD56⁺, lymphocyte, and total leukocyte), cytokine, Immunoglobulin (Igs), C-reactive protein (CRP) among Pb-exposed and unexposed controls were systematically searched from PubMed, Scopus and Embase digital databases from inception to January 2021. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were adhered during systematic review. Mean differences in the immunological markers between Pb-exposed and control groups were pooled using random-effects model. The heterogeneity was assessed using Cochran-Q test and I² statistic. The review included forty studies reporting immunological markers in Pb-exposed and unexposed control groups. The occupational Pb-exposed group exhibited significantly higher BLL, impaired immunological markers, characterized by a marginal lowering in lymphocyte count, lymphocyte subsets (CD3⁺, CD4⁺, CD4⁺/CD8⁺ ratio), IFN-γ and IgG levels, while CD8⁺, IgM, IgA, IgE, and cytokines (IL-4, IL-6, IL-10, and TNF-α) exhibited a trend of higher values in comparison to the control group. Further, inflammatory marker viz., total leukocyte count was significantly higher among Pb-exposed. The included studies exhibited high levels of heterogeneity. In conclusion, Occupational Pb exposure alters the immunological markers such as the circulating cytokines and leukocyte counts. However, high-quality, multicentered studies are required to strengthen present observations and further understand the Pb's role on the immune system. Prospero Registration ID: CRD42021228252.

Ambient air pollution and inflammatory effects in a Canadian pregnancy cohort

Supplemental Digital Content is available in the text.

Background:

Epidemiologic studies have consistently reported associations between air pollution and pregnancy outcomes including preeclampsia and gestational diabetes. However, the biologic mechanisms underlying these relationships remain unclear as few studies have collected relevant biomarker data. We examined relationships between ambient PM_2.5 and NO₂ with markers of inflammation during pregnancy in a prospective cohort of Canadian women.

Methods:

We analyzed data from 1170 women enrolled in the Maternal-Infant Research on Environmental Chemicals study. Daily residential PM_2.5 and NO₂ exposures during pregnancy were estimated using satellite-based and land-use regression models and used to create 14-day and 30-day exposure windows before blood-draw. Inflammatory markers C-reactive protein, interleukin-6, interleukin-8, and tumor necrosis factor-α were measured in third trimester plasma samples. Multivariable linear regression was used to estimate associations for an interquartile range (IQR) increase in PM_2.5 and NO₂ and markers of inflammation, while adjusting for individual-level confounders.

Results:

Fourteen-day (IQR: 6.85 µg/m³) and 30-day (IQR: 6.15 µg/m³) average PM_2.5 exposures before blood-draw were positively associated with C-reactive protein after adjustment for covariates (24.6% [95% CI = 9.4, 41.9] and 17.4% [95% CI = 1.0, 35.0] increases, respectively). This association was found to be robust in several sensitivity analyses. Neither PM_2.5 nor NO₂ exposures were associated with interleukin-6, interleukin-8, or tumor necrosis factor-α.

Conclusion:

Exposure to ambient PM_2.5 is positively associated with maternal inflammatory pathways in late pregnancy. This may contribute to positive associations between ambient PM_2.5 and risk of adverse pregnancy outcomes.

Blood lead level and nutritional status indicators in preadolescent Polish schoolchildren

BACKGROUND

Environmental pollutions with heavy metals may have toxic effects on human health and development. One of the most detrimental is lead exposure, which may disturb neurodevelopment and linear growth in children. However, data on the effect of lead exposure on nutritional and weight status in children are limited, thus this study aimed to assess the effect of blood lead (Pb) level on nutritional and weight status in preadolescent schoolchildren from the industrialized, mining region in southwestern Poland.

METHODS

Our study sample involved N = 709 schoolchildren (402 boys and 307 girls) in the preadolescent developmental period (7-11 years of age for boys and 7-10 years of age for girls). Anthropometric measurements were used to assess nutritional and weight status: body mass index (BMI), mid-upper arm circumference (MUAC) and skinfolds thicknesses (triceps, subscapular, abdominal and the sum of skinfolds). Blood Pb level was evaluated and divided into two groups: above (>3.7 μg/dL) and below median value (≤3.7 μg/dL).

RESULTS

Analysis of covariance (with children's age controlled as a covariate) revealed that children with blood Pb level above median value had significantly lower values of BMI, MUAC and all skinfolds (at least p < 0.01). However, this effect was significant only in boys, whereas in girls differences were non-significant (p > 0.05). The highest effect size of blood Pb level was noted for skinfolds thicknesses (partial η²: 0.015 for the sum of skinfolds).

CONCLUSIONS

Nutritional status in children with higher blood Pb level is significantly impaired in preadolescent boys, who appear to be more sensitive to this environmental factor. Our findings indicate a particular need for nutritional and environmental interventions among preadolescent children in regions with higher lead exposure.

Medicolegal Implications of Mild Neurocognitive Disorder

INTRODUCTION

The syndromes of mild cognitive impairment (MCI) or mild neurocognitive disorder (MiND), often prodromal to dementia (Major Neurocognitive Disorder), are characterized by acquired clinically significant changes in one or more cognitive domains despite preserved independence. Mild impairment has significant medicolegal consequences for an affected person and their care system. We review the more common etiologies of MiND and provide a systematic review of its medicolegal implications.

METHODS

We conducted a systematic review of the peer-reviewed English literature on medicolegal aspects of MCI or MiND using comprehensive search terms and expanding our review to include sources cited by these reports.

RESULTS

Impairment of memory, executive function, social cognition, judgment, insight or abstraction can alter an individual's abilities in a variety of areas that include decision making, informed consent, designation of a surrogate decision-maker such as a health care proxy, understanding and management of financial affairs, execution of a will, or safe driving.

CONCLUSION

Even mild cognitive impairment can have significant behavioral consequences. Clinicians can assist care partners and persons with MCI or MiND by alerting them to the medicolegal concerns that often accompany cognitive decline. Early recognition and discussion can help a care system manage medicolegal risk more effectively and promote thoughtful advance planning.

Systemic inflammation mediates the association of heavy metal exposures with liver injury: A study in general Chinese urban adults

Heavy metal exposures have been reported to be associated with increased risk for liver injury. However, the potential mechanisms of the association remain unclear. A repeated-measure study of 9367 observations was conducted to quantify the associations of urinary heavy metals with serum alanine aminotransferase (ALT), a biomarker for liver injury, and assess the mediating role of systemic inflammation in such associations among general Chinese adults. In single-metal models, positive dose-response relationships between urinary vanadium (V), chromium (Cr), copper (Cu), arsenic (As), cadmium (Cd), tungsten (W), and lead (Pb) and serum ALT were observed. In the multiple-metal model containing the seven metals mentioned above, V and Cu remained positively associated with ALT. In longitudinal analyses of 3-6 years, each 1-unit increase in log-transformed levels of V and Cu was associated with an additional rate of annual ALT increase (95% CI) for 1.3% (0.7-1.8%) and 1.3% (0.7-2.0%), respectively. Plasma CRP concentrations were not only positively associated with urinary Cu and Cd, but also positively related with ALT. Furthermore, mediation analyses showed that CRP mediated 4.70% and 7.03% of urinary Cu- and Cd-associated ALT elevations. Our study provides clues for the prevention of heavy metal-induced liver injury.

Lead (Pb) induced Oxidative Stress as a Mechanism to Cause Neurotoxicity in Drosophila melanogaster

The widespread use of lead (Pb) has caused global contamination, inevitable human exposure, and public health problems. Pb neurotoxicity has been linked to various human diseases, but its associated mechanism causing neurotoxicity is unknown. Drosophila melanogaster as a model organism has been used to study the mechanism involved in Pb-caused neurotoxicity and the potential role of antioxidants in ameliorating its harmful effects. The larval feeding technique was adopted to administer different concentrations of Pb (0.2-0.8 mM) to Oregon-R (ORR), superoxide dismutase (Sod), or catalase (Cat) overexpressing, and Sod or Cat knockdown flies to analyse Pb load, oxidative stress components, DNA damage, apoptosis and vacuolation in the brain. The results revealed that Pb accumulation in the Drosophila brain induces oxidative stress by generating reactive oxygen species (ROS) and lipid peroxidation (LPO), depleting antioxidant enzymes. Molecular docking studies have evidenced it. Pb directly binds to antioxidants and major grooves of DNA, leading to DNA damage. Increased DNA damage, apoptosis, vacuolation in brains of Pb-treated ORR, Sod, or Cat knockdown flies; and on the contrary, reduced oxidative DNA damage, apoptosis, and vacuolation in brains of Pb treated Sod or Cat overexpressed flies put forward that oxidative stress is the mechanism in Pb caused neurotoxicity.

The correlation between uremic pruritus and blood lead levels in prevalent hemodialysis patients and its relation to the severity of pruritus using visual analog score

Background

Pruritus is a common and often distressing symptom in patients with chronic kidney disease. Though the pathogenesis of uremic pruritus remains poorly understood, systemic inflammation has presented itself as one of the possible explanations. High blood lead levels (BLLs) have been noted to be associated with inflammation and poor nutritional status in hemodialysis patients. Our aim is to study the relation between blood lead levels and uremic pruritus. This is a cross-sectional study that enrolled 50 patients; all were on regular hemodialysis 3 times per week for at least 6 months. Patients were divided into 2 groups, group 1 (n =10) with no pruritus and group 2 (n=40) with varying degrees of pruritus. Group 2 was further divided according to intensity of pruritus by visual analog score (VAS) into mild (n=10), moderate (n=20), and severe pruritus (n=10).

Results

There was a significant difference in serum lead levels and ferritin levels between groups 1 and 2 (p value < 0.01 and < 0.05, respectively). There was a statistically significant difference in serum lead levels in the groups with varying intensity of pruritus, having higher serum lead levels in patients who exhibited severe pruritus (p value < 0.005) Moreover, a statistically significant relation between elevated blood lead levels and the duration of dialysis was observed in this study.

Conclusion

Uremic pruritus is a multi-factorial phenomenon, and our study showed that blood lead levels in hemodialysis patients might be associated with increased intensity of pruritus.

Early occupational exposure to lead on neutrophil-to-lymphocyte ratio and genotoxicity

BACKGROUND

Lead (Pb) is known to induce detrimental health effects in exposed populations, including hematotoxicity and genotoxicity. Complete blood count (CBC) is a cost-effective and easy way to determine toxicity, and variations in proportion of different types of leukocytes: neutrophil-to-lymphocyte ratio (NLR) and lymphocyte-to-monocyte ratio (LMR) are further evidence of hematotoxicity. However, few studies have been conducted to systematically evaluate effects of occupational Pb exposure on NLR and LMR, and their associations with genotoxicity.

OBJECTIVES

Our study was aimed to systematically assess the effects of current occupational Pb exposure on NLR and LMR, and their associations with genotoxicity.

METHODS

Our investigation was performed on 1176 workers from a newly built battery factory in North China. The workers had just entered their current job position in recent years and most of them had no previous history of occupational exposure to Pb. Blood lead levels (BLLs) and leukocytes indices were detected for all participants. Cytokinesis-blocked micronucleus assay (MN; n = 675) and alkaline comet assay (% tail DNA; n = 869) were used to assess genotoxicity. Multivariate linear and Poisson regression analyses were conducted to examine associations between leukocytes indices, genotoxic biomarkers and BLLs with adjustment for covariates. Spearman correlation and mediation analyses were used to investigate relationships between NLR and genotoxicity.

RESULTS

Among all the exposed workers, NLR increased with increasing BLLs. However, WBC and LMR did not change significantly. Significant and dose-dependent increases in both MN frequencies and % tail DNA were observed among groups with different exposure doses. Compared with the normal NLR group (1.48 ≤ NLR < 4.58), the high NLR group (NLR ≥ 4.58) had higher % tail DNA. In addition, there was a significant and positive association between NLR and % tail DNA among all the workers, and % tail DNA mediated 15% of the effect of Pb on increasing NLR.

CONCLUSION

Our large-scale population study shows that Pb exposure increased NLR and induced genotoxicity. There was an association between elevated NLR and DNA damage. In addition, the mediation effect of % tail DNA on the relationship between BLLs and NLR provided mechanistic evidence that certain mechanisms, e.g. inflammation, may be involved in elevation of NLR from Pb exposure. Therefore, NLR may be a convenient and sensitive biomarker for indication of Pb toxicity. Further studies are needed to validate the proposed mechanism and NLR as a biomarker.

Relations of blood lead levels to echocardiographic left ventricular structure and function in preschool children

Lead (Pb) has been proved to exert adverse effect on human cardiovascular system. However, the cardiotoxicity of Pb on children is still unclear. The aim of this study was to evaluate left ventricular (LV) structure and function, by using echocardiographic indices, in order to elucidate the effect of Pb on low-grade inflammation related to left ventricle in healthy preschool children. We recruited a total of 486 preschool children, 310 from Guiyu (e-waste-exposed area) and 176 from Haojiang (reference area). Blood Pb levels, complete blood counts, and LV parameters were evaluated. Associations between blood Pb levels and LV parameters and peripheral leukocyte counts were analyzed using linear regression models. The median blood level of Pb and the counts of white blood cells (WBCs), monocytes, and neutrophils were higher in exposed group. In addition, the exposed group showed smaller left ventricle (including interventricular septum, LV posterior wall, and LV mass index) and impaired LV systolic function (including LV fractional shortening and LV ejection fraction) regardless gender. After adjustment for confounding factors, elevated blood Pb levels were significantly associated with higher counts of WBCs and neutrophils, and lower levels of LV parameters. Furthermore, counts of WBCs, monocytes, and neutrophils were negatively correlated with LV parameters. Taken together, smaller left ventricle and impaired systolic function were found in e-waste-exposed children and associated with chronic low-grade inflammation and elevated blood Pb levels. It indicates that the heart health of e-waste-exposed children is at risk due to the long-term environmental chemical insults.

Biomonitoring of Lead Exposure in Children from Two Fishing Communities at Northern Colombia

Lead (Pb) exposure is a growing concern in developing countries, especially in vulnerable children. The objective of this study was to evaluate blood lead levels (BLL) in children from two fishing populations at Northern Colombia, Loma de Arena and Tierrabomba, as well as their association with morphometric parameters, markers of hematological status, liver function, and mRNA expression of genes related to Pb toxicity. A total of 198 blood samples were collected from participants aged 5-16 years old. The mean (± standard error) BLL for the studied sample was 3.6 ± 0.3 μg/dL, and the 97.5th percentile was 21.0 μg/dL. The participants of Loma de Arena and Tierrabomba presented BLL of 3.9 ± 0.5 and 2.9 ± 0.3 μg/dL, respectively. Children born preterm had greater BLL than those born at full term. Boys had greater BLL than girls, which also occurred for participants between 12 and 16 years old, compared with those aged 5-11 years old. The BLL were negatively correlated with body mass index in children from Loma de Arena, but an opposite behavior was observed for Tierrabomba. In Loma de Arena, the mRNA expression of interferon gamma, a pro-inflammatory cytokine, increased with the BLL, but that of δ-aminolevulinic acid dehydrogenase, a sensor for Pb poisoning, decreased. In Tierrabomba, gene expression did not change with BLL. These results show that in fishing communities, lead exposure promotes different health impacts depending on age, sex, and other site-specific factors. In any case, appropriate educational and intervention programs should be carried out to minimize Pb exposure in children.

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.

The protective effect of Ocimum sanctum leaf extract against lead acetate-induced nephrotoxicity and hepatotoxicity in mice (Mus musculus)

AIM

The liver and kidneys are the most sensitive organs to lead exposure. Drugs that inhibit the actions of lead in the liver and kidneys are required to protect them from such an exposure. This study investigates the protective effect of the leaf extract of Ocimum sanctum (OS) against lead acetate-induced nephrotoxicity and hepatotoxicity in mice.

MATERIALS AND METHODS

A total of 20 male mice were divided into five equal groups for the 24-day testing period. The negative control group was administered Tween-80 1% orally for 24 days. The positive control group was administered Tween-80 1% orally for 24 days and, starting on day 4, 20 mg/kg BW lead acetate orally once a day for 21 days 1 h after the administration of Tween-80 1%. The other three treatment groups were administered BW OS leaf extract orally in the amount of 140, 280, and 560 mg/kg once a day for 24 days and, starting on day 4, 20 mg/kg BW lead acetate orally for 21 days 1 h after the administration of OS leaf extract. On day 25, the mice were sacrificed to assess the levels of blood urea nitrogen (BUN), creatinine, malondialdehyde (MDA), serum glutamic-oxaloacetic transaminase (SGOT), and serum glutamic-pyruvic transaminase (SGPT) as well as the histopathological changes.

RESULTS

The OS leaf extract caused a decrease in the scores for hepatocyte degeneration and portal inflammation (p<0.05) but not for hepatic necrosis (p>0.05) in mice exposed to lead. Similar patterns were observed in the effect of OS leaf extract on the renal morphofunction. The OS leaf extract decreased the scores for hydropic degeneration, tubular necrosis, and glomerular necrosis. The levels of MDA, SGOT, SGPT, BUN, and creatinine decreased in the lead-exposed mice treated with OS leaf extract (p<0.05).

CONCLUSION

The administration of OS leaf extract has a protective effect against lead acetate-induced hepatotoxicity and nephrotoxicity in mice.

Umbelliferone Inhibits Spermatogenic Defects and Testicular Injury in Lead-Intoxicated Rats by Suppressing Oxidative Stress and Inflammation, and Improving Nrf2/HO-1 Signaling

INTRODUCTION

Lead (Pb) is an environmental toxic metal that threatens human health. Umbelliferone (UMB) is a coumarin with known medicinal and protective properties against cytotoxicity. This study explored the ameliorative effect of UMB against Pb-induced testicular toxicity in rats, focusing on steroidogenesis, oxidative stress and inflammation.

MATERIALS AND METHODS

Rats received lead acetate (50 mg/kg) and UMB (25, 50 or 100 mg/kg) via oral gavage for 4 weeks.

RESULTS

Pb-intoxicated rats exhibited testicular tissue injury and decreased serum levels of LH, FSH and testosterone. The count, viability, motility and normal morphology of the sperms were decreased accompanied with downregulated steroidogenesis markers in Pb-induced group. UMB prevented testicular injury, increased serum levels of LH, FSH and testosterone, upregulated steroidogenesis markers and improved the semen quality. In addition, UMB attenuated oxidative stress and oxidative DNA damage, downregulated the expression of pro-inflammatory mediators and Bax, boosted antioxidant defenses and Bcl-2, and upregulated Nrf2/HO-1 signaling in Pb-intoxicated rats.

CONCLUSION

UMB prevents Pb-induced testicular injury by suppressing oxidative damage, inflammation and cell death, and boosting antioxidant defenses, Nrf2/HO-1 signaling and pituitary-gonadal axis. Thus, UMB may represent a protective and cost-effective agent against Pb testicular toxicity, pending further investigations to elucidate other underlying mechanisms.

Elevated, sustained, and yet reversible biotoxicity effects of lead on cessation of exposure: Melatonin is a potent therapeutic option

Melatonin (Mel) is known to prevent and mitigate lead (Pb)-induced gonadotoxicity. However, there is no report in literature on the endogenous levels of different biomarkers after the cessation of Pb exposure, with or without treatment with Mel. Fifty adult male Wistar rats were divided into five groups (N = 10), which included control ((vehicle (normal saline) - treated) - 0.1 ml/day); lead chloride (PbCl₂) untreated (3 weeks vehicle + 3 weeks Pb); Pb recovery (3 weeks Pb + 3 weeks vehicle); Pb + Mel (3 weeks Pb + 3 weeks Mel); and Mel (3 weeks vehicle + 3 weeks Mel) groups. Pb and Mel were administered at 50 and 10 mg/kg B.W. (p.o.), respectively. The results showed that Pb caused significant decreases in total bilirubin (TB), phospholipids (PLP), superoxide dismutase (SOD), catalase (CAT), and total antioxidant capacity (TAC), but significant elevations in alkaline phosphatase (ALP), aspartate aminotransferase (AST), triglyceride (TG), and malondialdehyde (MDA). Although the adverse effects of Pb on TB, ALP, AST, SOD, MDA, and TAC were sustained after the cessation of exposure, a reversal was observed in total cholesterol (TC), TG, PLP, CAT, and c-reactive protein (CRP) results. Nevertheless, the detrimental effects of Pb on alanine aminotransferase (ALT), albumin, and globulin were only expressed post-exposure. Treatment with Mel caused no significant effect on TB and albumin levels. However, unlike TAC and CRP, the hormone significantly reduced ALP, AST, ALT, TC, low-density lipoprotein cholesterol, PLP, SOD, CAT, MDA, and globulin to levels comparable to the control group. In conclusion, following the cessation of Pb exposure, alterations in physiological balance could be elevated, sustained, or reversible. However, Mel enhanced the reestablishment homeostatic status after Pb administration.

Antioxidant, anti-inflammatory and anti-apoptotic effects of hydro-ethanolic extract of Cyperus esculentus L. (tigernut) on lead acetate-induced testicular dysfunction in Wistar rats

AIM

Lead acetate impairs testicular function by enhancing testicular oxidative stress and apoptosis. Cyperus esculentus possesses antioxidants and has shown great improvement of testicular function. This study investigated the protective effect of hydro-ethanolic extract of Cyperus esculentus on lead acetate-induced testicular dysfunction in Wistar rats.

MATERIALS AND METHODS

Twenty-five male Wistar rats (180-195 g) were randomly divided into 5 groups (n = 5) namely: Normal control (NC), Lead control (PbC) (20 mg/kg b.w. i.p.), C. esculentus-treated (CE) (500 mg/kg b.w p.o.), Pb + CE(500) (20 mg/kg of lead and 500 mg/kg of extract) and Pb + CE(1000) (20 mg/kg of lead and 1000 mg/kg of extract). Administration lasted for 21 days.

RESULTS

Sperm count, motility, viability, serum testosterone and follicle stimulating hormone, Johnsen's score, Leydig cell count, Sertoli cell count, testicular testosterone, B-cell lymphoma protein-2 (Bcl-2), steroidogenic acute regulatory protein, cytochrome P450 A1, 3β-hydroxysteroid dehydrogenase (HSD), 17β-HSD, enzymatic antioxidant activities and total antioxidant capacity were significantly (p < 0.05) decreased in PbC compared with NC. These parameters however increased significantly (p < 0.05) in Pb + CE(500) and Pb + CE(1000) compared with PbC. Lead acetate upregulated (p < 0.05) testicular malondialdehyde, nitric oxide, glucose, lactate, lactate dehydrogenase, C-reactive protein, tumor necrosis factor-α, interleukin (IL)-6, IL-1β, Bcl-2 associated X (Bax), Bax/Bcl-2 and cleaved caspase-3 levels. All these parameters were downregulated (p < 0.05) in Pb + CE(500) and Pb + CE(1000) in comparison with PbC.

CONCLUSION

C. esculentus exhibited a dose-dependent mitigation of lead acetate-induced testicular dysfunction in Wistar rats via its antioxidant, anti-inflammatory and anti-apoptotic effects.

Microanatomy, lipid peroxidation and antioxidant system of the visual cortex of rats following withdrawal from prolonged lead nitrate administration

Exposure to lead (Pb) has been shown to alter the function of central nervous system and affect cholinergic neurons of the visual cortex in animal models. This study sought to investigate the withdrawal symptoms and oxidative stress on the visual cortex after lead exposure. A total of 20 healthy male Wistar rats were randomly divided into two groups (n=10): group A, control, received 10 ml/kg of distilled water for 30 days orally; group B, lead treated group, received 10 mg/kg of lead nitrate solution for 30 days orally. Group B was divided into two subgroups, group B1 serves as non-recovery while B2 serves as recovery (withdrawal). Five rats from each group were sacrificed under ether anesthesia 24 hours after the last oral administration of lead, while the remaining 5 rats (withdrawal subgroup) were sacrificed 30 days after the last oral administration of lead. The visual cortex was grossed from the brain tissue and processed for histology. Blood/serum samples were obtained and markers of oxidative stress (superoxide dismutase [SOD], catalase [CAT], glutathione peroxidase [GPX]), and lipid peroxidation (malondialdehyde [MDA]) were analyzed. Lead-exposed rats display a significant reduction in the SOD, CAT, and GPX level as well as increased in MDA level. However, following a recovery period, a non-significant improvement was seen in the histoarchitecture of the visual cortex.

Leukocyte apoptosis, TNF-α concentration and oxidative damage in lead-exposed workers

Lead intoxication can generate pro-inflammatory conditions that have been proposed to be associated with cell injuries and oxidative stress. The pro-inflammatory state can participate in the pathophysiology of this toxicity to generate immune response dysfunctions, which could condition the presence of clinical manifestations and susceptibility to infections already described in lead-exposed patients. In the present work, we study workers of a battery recycler factory (n = 24) who are chronically exposed to lead and compared them with non-lead exposed workers (n = 17). Lead-exposed workers had high lead concentrations in blood (med 69.8 vs. 1.7 μg/dL), low δ-ALAD activity (med 149 vs. 1100 nmol PBG/h/mL), high lipid peroxidation (med 0.86 vs. 0.69 nmol/mL) and high erythrocytes apoptosis (med 0.81 vs. 0.50% PS externalization) in relation to non-lead exposed workers. Also, lead-exposed workers had a high incidence of signs and symptoms related to lead intoxication and a higher frequency of infections. The higher leukocyte apoptosis (med 18.3 vs. 8.2% PS externalization) and lower basal TNF-α concentration (med 0.38 vs. 0.94 pg/mL) in lead-exposed workers imply an immune response dysfunction; however, there was no difference in the TNF-α concentration when leukocytes were stimulated with lipopolysaccharide in whole blood (med 44 vs. 70 pg/mL), suggesting that lead-exposed workers might develop adaptation mechanisms to reduce basal TNF-α release through downregulation processes proposed for this cytokine.

Increased blood lead level induces oxidative stress and alters the antioxidant status of spray painters

Background The aim of this study was to know the present scenario of blood lead level and its effect on serum lipid peroxide and antioxidant parameters of spray painters. Methods We included 42 male spray painters and 50 control subjects with an age range of 20-45 years. Blood lead level, serum lipid peroxide and antioxidant parameters, i.e. erythrocyte catalase, superoxide dismutase (SOD), plasma ceruloplasmin, nitric oxide, uric acid and bilirubin, were quantified by standard methods. Results We observed the significant elevated blood lead (p < 0.001, 458%), lipid peroxide (p < 0.001, 170%), uric acid (p < 0.001, 25.6%) and bilirubin (p < 0.01, 24.5%) and the significant decrease in antioxidant enzymes like SOD (p < 0.001, -50.4%), catalase (p < 0.001, -34.33%), ceruloplasmin (p < 0.001, -32.7%) and nitric oxide (p < 0.001, -39.58%) in the study group as compared to control. A significant positive correlation coefficient (r) of blood lead level with lipid peroxide (r = 0.44, p < 0.001), uric acid (r = 0.33 p < 0.05) and bilirubin (r = 0.35, p < 0.05) and a negative correlation with SOD (r = -0.32, p < 0.05), catalase (r = -0.33, p < 0.05), ceruloplasmin (r = -0.27, p < 0.05) and nitric oxide (r = 0.30, p < 0.05) were observed. Conclusions Elevated blood lead level induces serum lipid peroxide and alters the antioxidant enzymes of spray painters. Therefore, it is necessary to reduce the blood lead level by taking proper precautions while spraying the paints, and additional antioxidant supplementation like vitamin C, multivitamin and multiminerals will be useful in reducing oxidative stress.

Arctium lappa Root Extract Prevents Lead-Induced Liver Injury by Attenuating Oxidative Stress and Inflammation, and Activating Akt/GSK-3β Signaling

Arctium lappa L. (A. lappa) is a popular medicinal plant with promising hepatoprotective activity. This study investigated the protective effect of A. lappa root extract (ALRE) on lead (Pb) hepatotoxicity, pointing to its ability to modulate oxidative stress, inflammation, and protein kinase B/Akt/glycogen synthase kinase (GSK)-3β signaling. Rats received 50 mg/kg lead acetate (Pb(Ac)₂) and 200 mg/kg ALRE or vitamin C (Vit. C) for 7 days, and blood and liver samples were collected. Pb(Ac)₂ provoked hepatotoxicity manifested by elevated serum transaminases and lactate dehydrogenase, and decreased total protein. Histopathological alterations, including distorted lobular hepatic architecture, microsteatotic changes, congestion, and massive necrosis were observed in Pb(II)-induced rats. ALRE ameliorated liver function and prevented all histological alterations. Pb(II) increased hepatic lipid peroxidation (LPO), nitric oxide (NO), caspase-3, and DNA fragmentation, and serum C-reactive protein, tumor necrosis factor-α, and interleukin-1β. Cellular antioxidants, and Akt and GSK-3β phosphorylation levels were decreased in the liver of Pb(II)-induced rats. ALRE ameliorated LPO, NO, caspase-3, DNA fragmentation and inflammatory mediators, and boosted antioxidant defenses in Pb(II)-induced rats. In addition, ALRE activated Akt and inhibited GSK-3β in the liver of Pb(II)-induced rats. In conclusion, ALRE inhibits liver injury in Pb(II)-intoxicated rats by attenuating oxidative injury and inflammation, and activation of Akt/GSK-3β signaling pathway.

Curcumin Ameliorates Lead-Induced Hepatotoxicity by Suppressing Oxidative Stress and Inflammation, and Modulating Akt/GSK-3β Signaling Pathway

Lead (Pb) is a toxic heavy metal pollutant with adverse effects on the liver and other body organs. Curcumin (CUR) is the principal curcuminoid of turmeric and possesses strong antioxidant and anti-inflammatory activities. This study explored the protective effect of CUR on Pb hepatotoxicity with an emphasis on oxidative stress, inflammation and Akt/GSK-3β signaling. Rats received lead acetate and CUR and/or ascorbic acid (AA) for seven days and samples were collected for analyses. Pb(II) induced liver injury manifested by elevated serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) and lactate dehydrogenase (LDH), as well as histopathological alterations, including massive hepatocyte degeneration and increased collagen deposition. Lipid peroxidation, nitric oxide, TNF-α and DNA fragmentation were increased, whereas antioxidant defenses were diminished in the liver of Pb(II)-intoxicated rats. Pb(II) increased hepatic NF-κB and JNK phosphorylation and caspase-3 cleavage, whereas Akt and GSK-3β phosphorylation was decreased. CUR and/or AA ameliorated liver function, prevented tissue injury, and suppressed oxidative stress, DNA damage, NF-κB, JNK and caspase-3. In addition, CUR and/or AA activated Akt and inhibited GSK-3β in Pb(II)-induced rats. In conclusion, CUR prevents Pb(II) hepatotoxicity via attenuation of oxidative injury and inflammation, activation of Akt and inhibition of GSK-3β. However, further studies scrutinizing the exact role of Akt/GSK-3β signaling are recommended.

Association of Typical Toxic Heavy Metals with Schizophrenia

Toxic heavy metals (THMs) are contaminants commonly found in the environment. Although a large number of studies have demonstrated their damage to the biological functions of the human being, their potential associations with the risk of developing schizophrenia remain controversial. In this study, we investigated the associations between four THMs (chromium (Cr), cadmium (Cd), lead (Pb) and arsenic (As)) in serum and the risk of schizophrenia. In total, 95 patients with schizophrenia (cases) and 95 normal subjects (controls) were recruited from Hebei Province, China. The serum concentrations of the 4 THMs were analyzed by inductively coupled plasma mass spectrometry (ICP-MS). A higher concentration of Pb was found significantly associated with an elevated risk of schizophrenia (OR = 3.146; 95%CI: 1.238–7.994, p = 0.016), while significant association for the other three THMs were not observed. Besides, significant correlations were found between the metabolic biomarkers and the concentrations of Pb and As, respectively. In order to further characterize the association between these THMs and schizophrenia with greater statistical power, we conducted meta-analysis by including 538 cases and 1040 controls from the current study and 5 available datasets published from 2002 to 2018. Using a random-effect model, Cr was significantly associated with schizophrenia (SMD = 0.3246; 95%CI: 0.0166–0.6326, p < 0.01). Overall, this study suggested that higher levels of Pb and Cr may be one of the factors associated with an elevated risk of schizophrenia.

The effect of subacute lead exposure on selected blood inflammatory biomarkers and angiogenetic factors

Objectives:

The aim of the study was to examine blood levels of selected pro-inflammatory cytokines, C reactive protein (CRP), and selected factors that influence angiogenesis in workers exposed to lead for a short period of time.

Methods:

The study population consisted of 36 male workers (mean age 41 ± 14 years) exposed to lead for 40 days.

Results:

The mean blood lead level (BLL) was 10.7 ± 7.67 μg/dl at the beginning of the study, and increased to 49.1 ± 14.1 μg/dl at the end of the study period. The levels of macrophage inflammatory protein 1-α (MIP-1α) were significantly higher after the studied exposure to lead compared to the baseline by 71%. Similarly, the values of CRP increased by 35%. Conversely, the values of soluble vascular endothelial growth factor receptor-1 (sVEGFR-1) and fibroblast growth factor-basic (FGF-basic) decreased by 14% and 21%, respectively. After the examined period of lead exposure, analysis of correlations showed positive correlations between vascular endothelial growth factor (VEGF) levels and the levels of interleukin 1β (IL-1β) (R = 0.39), interleukin 6 (IL-6) (R = 0.42), and MIP-1α (R = 0.54). Positive correlations were identified between MIP-1α and FGF-basic (R = 0.38), soluble angiopoietin receptor (sTie-2) (R = 0.41), and sVEGFR-1 (R = 0.47).

Discussion:

Short-term exposure to lead induces the inflammatory response; however, these mechanisms seem to be different from those observed in chronic lead exposure. Subacute exposure to lead may dysregulate angiogenesis via modifications in the levels of angiogenic factors.

Lead (Pb) Exposure Enhances Expression of Factors Associated with Inflammation

The human immune system is constantly exposed to xenobiotics and pathogens from the environment. Although the mechanisms underlying their influence have already been at least partially recognized, the effects of some factors, such as lead (Pb), still need to be clarified. The results of many studies indicate that Pb has a negative effect on the immune system, and in our review, we summarize the most recent evidence that Pb can promote inflammatory response. We also discuss possible molecular and biochemical mechanisms of its proinflammatory action, including the influence of Pb on cytokine metabolism (interleukins IL-2, IL-4, IL-8, IL-1b, IL-6), interferon gamma (IFNγ), and tumor necrosis factor alpha (TNF-α); the activity and expression of enzymes involved in the inflammatory process (cyclooxygenases); and the effect on selected acute phase proteins: C-reactive protein (CRP), haptoglobin, and ceruloplasmin. We also discuss the influence of Pb on the immune system cells (T and B lymphocytes, macrophages, Langerhans cells) and the secretion of IgA, IgE, IgG, histamine, and endothelin.

Cardiovascular-Related Outcomes in U.S. Adults Exposed to Lead

Cardiovascular-related clinical markers were evaluated in this cross-sectional study of United States adults (aged ≥ 20) exposed to lead via the National Health and Nutrition Examination Survey 2007-2008 and the 2009-2010 datasets. In four quartiles of exposure-0-2 μg/dL, 2-5 μg/dL, 5-10 μg/dL, and 10 μg/dL and over, clinical and anthropometric markers were evaluated-to examine how the markers manifested in the quartiles. Associations were determined via linear regression. Finally, clinical makers, and how they manifested between exposed and less-exposed occupations, were explored in addition to how duration of exposure altered these clinical markers. In regression analysis, Diastolic Blood Pressure (DBP) and high-density lipoprotein (HDL) cholesterol, were significantly associated with blood lead level (BLL). In the occupational analysis, Systolic Blood Pressure (SBP), DBP, C-reactive protein (CRP), triglycerides, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, showed differences between populations in the exposed and less-exposed occupations. Regarding Agriculture, Forestry & Fishing, the duration of exposure altered SBP, CRP, and LDL cholesterol. With mining, the duration of exposure altered SBP, DBP, triglycerides, and HDL cholesterol, whereas in construction, the duration in occupation altered SBP, triglycerides, and CRP. In conclusion, lead exposure has a profound effect on the cardiovascular system, with potentially adverse outcomes existing at all exposure levels.

Hearing loss, lead (Pb) exposure, and noise: a sound approach to ototoxicity exploration

To determine the state of the research on ototoxic properties of Pb, evaluate possible synergistic effects with concurrent noise exposure, and identify opportunities to improve future research, we performed a review of the peer-reviewed literature to identify studies examining auditory damage due to Pb over the past 50 years. Thirty-eight studies (14 animal and 24 human) were reviewed. Of these, 24 suggested potential ototoxicity due to Pb exposure, while 14 found no evidence of ototoxicity. More animal studies are needed, especially those investigating Pb exposure levels that are occupationally and environmentally relevant to humans. Further investigations into potential interactions of Pb in the auditory system with other hazards and compounds that elicit ototoxicity are also needed in animal models. To better assess the effects of Pb exposure on the human auditory system and the possibility of a synergism with noise, future epidemiological studies need to carefully consider and address four main areas of uncertainty: (1) hearing examination and quantification of hearing loss, (2) Pb exposure evaluation, (3) noise exposure evaluation, and (4) the personal characteristics of those exposed. Two potentially confounding factors, protective factors and mixtures of ototoxicants, also warrant further exploration.

Decreased zinc and increased lead blood levels are associated with endometriosis in Asian Women

Endometriosis is an inflammatory disease associated with multiple pathogenic factors and studies regarding roles of trace metals in endometriosis have been inconsistent and limited. The aim of this cross-sectional study was to compare the blood levels of miscellaneous trace metals measured by inductively coupled plasma mass spectrometry in infertile women with and without endometriosis. Zinc level is associated with declining odds (adjusted OR=0.39, 95% CI=0.18-0.88) of endometriosis. By contrast, lead level is associated with increasing odds (adjusted OR=2.59, 95% CI=1.11-6.06) of endometriosis. The cadmium levels were higher in women with endometriosis, but the aOR was not significant. Zinc has anti-inflammatory characteristics and regulates homeostasis of zinc-containing superoxide dismutase. High lead levels might induce reactive oxygen species and deplete antioxidant defense mechanisms. Further prospective study is needed to test for their causal associations.

Toxic Metal Pollution in Pakistan and Its Possible Risks to Public Health

Environmental pollution has increased many folds in recent years and in some places has reached levels that are toxic to living things. Among pollutant types, toxic heavy metals and metalloids are among the chemicals that pose the highest threat to biological systems (Jjemba 2004). Unlike organic pollutants, which are biodegradable, heavy metals are not degraded into less hazardous end products (Gupta et al. 2001). Low concentrations of some heavy metals are essential for life, but some of them like Hg, As, Pb and Cd are biologically non-essential and very toxic to living organisms. Even the essential metals may become toxic if they are present at a concentration above the permissible level (Puttaiah and Kiran 2008). For example, exposure to Zn and Fe oxides produce gastric disorder and vomiting, irritation of the skin and mucous membranes. Intake of Ni, Cr, Pb, Cd and Cu causes heart problems, leukemia and cancer, while Co and Mg can cause anemia and hypertension (Drasch et al. 2006). Similarly, various studies indicated that overexposure to heavy metals in air can cause cardiovascular disorders (Miller et al. 2007; Schwartz 2001), asthma (Wiwatanadate and Liwsrisakun 2011), bronchitis/emphysema (Pope 2000), and other respiratory diseases (Dominici et al. 2006).

α-Tocopherol supplementation and the oxidative stress, homocysteine, and antioxidants in lead exposure

To investigate whether α-tocopherol supplementation in workers exposed to lead would reduce the oxidative stress intensity and decrease homocysteine level, the examined population was randomly divided into two groups. Workers in the first group (n = 49, reference group) were not administered any drugs. Workers in the second group (n = 34) were administered orally α-tocopherol, 200 mg per day for 12 weeks. The level of α-tocopherol significantly increased compared to the baseline and the reference group. The level of thiol groups significantly increased compared to the reference group. However, the levels of malondialdehyde and homocysteine did not significantly change. Animal studies suggest the ability of α-tocopherol administration to reverse adverse health effects of lead exposure, such as oxidative stress; however, the results of this study on humans do not confirm these protective effects.

Oxidative DNA damage and oxidative stress in lead-exposed workers

There are many discrepancies among the results of studies on the genotoxicity of lead. The aim of the study was to explore lead-induced DNA damage, including oxidative damage, in relation to oxidative stress intensity parameters and the antioxidant defense system in human leukocytes. The study population consisted of 100 male workers exposed to lead. According to the blood lead (PbB) levels, they were divided into the following three subgroups: a group with PbB of 20-35 μg/dL (low exposure to lead (LE) group), a group with a PbB of 35-50 µg/dL (medium exposure to lead (ME) group), and a group with a PbB of >50 μg/dL (high exposure to lead (HE) group). The control group consisted of 42 healthy males environmentally exposed to lead (PbB < 10 μg/dL). A comet assay was used to measure the DNA damage in leukocytes. We measured the activity of superoxide dismutase (SOD), catalase, glutathione reductase (GR), glucose-6-phosphate dehydrogenase (G6PD), and glutathione-S-transferase (GST) as well as the concentration of malondialdehyde (MDA), and the value of the total antioxidant capacity. The level of PbB was significantly higher in the examined subgroups than in the control group. The percentage of DNA in the tail was significantly higher in the LE, ME, and HE subgroups than in the control group by 10% ( p = 0.001), 15% ( p < 0.001), and 20% ( p < 0.001), respectively. The activity of GR was significantly lower in the LE and ME subgroups than in the control group by 25% ( p = 0.007) and 17% ( p = 0.028), respectively. The activity of G6PD was significantly lower in the ME subgroup by 25% ( p = 0.022), whereas the activity of GST was significantly higher in the HE subgroup by 101% ( p = 0.001) than in the control group. Similarly, the activity of SOD was significantly higher in the LE and ME subgroups by 48% ( p = 0.026) and 34% ( p = 0.002), respectively. The concentration of MDA was significantly higher in the LE, ME, and HE subgroups than in the control group by 43% ( p = 0.016), 57% ( p < 0.001), and 108% ( p < 0.001), respectively. Occupational lead exposure induces DNA damage, including oxidative damage, in human leukocytes. The increase in DNA damage was accompanied by an elevated intensity of oxidative stress.

PGC-1α controls mitochondrial biogenesis and dynamics in lead-induced neurotoxicity

Due to its role in regulation of mitochondrial function, PGC1α is emerging as an important player in ageing and neurodegenerative disorders. PGC1α exerts its neuroprotective effects by promoting mitochondrial biogenesis (MB) and functioning. However, the precise regulatory role of PGC1α in the control of mitochondrial dynamics (MD) and neurotoxicity is still unknown. Here we elucidate the role of PGC1α in vitro and in vivo in the regulatory context of MB and MD in response to lead (II) acetate as a relevant model of neurotoxicity. We show that there is an adaptive response (AR) to lead, orchestrated by the BAP31-calcium signalling system operating between the ER and mitochondria. We find that this hormetic response is controlled by a cell-tolerated increase of PGC1α expression, which in turn induces a balanced expression of fusion/fission genes by binding to their promoters and implying its direct role in regulation of MD. However, dysregulation of PGC1α expression through either stable downregulation or overexpression, renders cells more susceptible to lead insult leading to mitochondrial fragmentation and cell death. Our data provide novel evidence that PGC1α expression is a key regulator of MD and the maintenance of tolerated PGC1α expression may offer a promising strategy for neuroprotective therapies.

Association between subchronic and chronic lead exposure and levels of antioxidants and chemokines

Purpose

This study aimed to compare the influence of lead on the non-enzymatic antioxidant defenses and the levels of chemokines in workers subchronically and chronically exposed to lead.

Methods

The study population was divided into three groups. The first group consisted of male workers subchronically exposed to lead for 40 ± 3.2 days, while the second group included male workers chronically exposed to lead. The third group was a control group.

Results

The levels of uric acid and bilirubin were significantly higher after a subchronic exposure to lead compared to the baseline by 22 and 35 %, respectively. Similarly, the values of total antioxidant capacity (TAC), total oxidant status (TOS), and oxidative stress index (OSI) increased by 15, 50, and 33 %, respectively. At the same time, the levels of thiol groups and albumin decreased by 5 and 8 %, respectively. Additionally, the levels of interleukin-8 (IL-8) and macrophage inflammatory protein-1β (MIP-1β) were significantly higher after a subchronic exposure to lead compared to the baseline by 34 and 20 %, respectively. Moreover, IL-8 level was significantly higher by 40 % in the group of workers chronically exposed to lead than in the control group, while the level of interferon gamma-induced protein-10 (IP-10) was significantly lower by 28 %.

Conclusions

Similar to chronic lead exposure, subchronic exposure to lead is associated with elevated blood levels of uric acid and bilirubin in humans. This probably results in increased TAC value despite thiol depletion. However, the compensatory activation of non-enzymatic antioxidant defenses seems to be insufficient to protect against lead-induced oxidative stress, which may be additively enhanced by the pro-inflammatory action of chemokines, especially IL-8.

Do people from Taiwan have higher heavy metal levels than those from Western countries?

INTRODUCTION

This study investigated whether heavy metal levels were higher in people from Taiwan as compared to those from Western countries.

METHODS

We measured the level of heavy metals (lead, mercury, arsenic and cadmium) in the blood of 40 apparently healthy adults. Since mercury does not respond to ethylenediaminetetraacetic acid (EDTA) infusion, only urine lead, arsenic and cadmium levels were determined by applying the body burden concept after calcium disodium EDTA infusion. These three heavy metals were extracted from daily urine samples for three consecutive days.

RESULTS

The mean blood lead, mercury and cadmium levels of the Taiwanese individuals (24.46 ± 9.69 µg/L, 9.64 ± 6.98 µg/L and 0.73 ± 0.27 µg/L, respectively) were greater than those of the Americans. The Taiwanese also had greater blood mercury and cadmium levels than the Germans. The first-day urine lead, arsenic and cadmium levels were 77.9%, 33.1% and 62.4%, respectively, of the total lead, arsenic and cadmium excretion during the three days. This indicates that the first-day urine lead and cadmium excretion represented most (> 60%) of the lead and cadmium excretion in those three days.

CONCLUSION

This study demonstrated that the Taiwanese population has higher blood mercury and cadmium levels than Western populations. To study the urine lead and cadmium body burden of patients, detection of first-day, rather than three-day, urine lead and cadmium levels can be done, as the former yields results that are fairly representative, and is more time- and cost-effective.

Lead Exposure and Oxidative Stress: A Systematic Review

Lead is an environmental toxicant that can induce oxidative stress (OS) via reactive oxygen species (ROS) generation, which has been reported as an important mechanism underlying lead toxicity (Gurer and Ercal 2000; Pande and Flora 2002; Kasperczyk et al. 2004a; Farmand et al. 2005; Verstraeten et al. 2008; Wang et al. 2009; Martinez-Haro et al. 2011). OS occurs when the generation of ROS exceeds the antioxidant system's ability to defend cells against oxidized molecules. ROS is a term generally used to refer to free radicals derived from O2 (e.g., superoxide anions [O2-] and hydroxyl radicals [OH-]) or to non-radical species (e.g. hydrogen peroxide [H2O2]) (Halliwell and Cross 1994).