Oxidative Stress Indices as Markers of Lead and Cadmium Exposure Toxicity in Auto Technicians in Ibadan, Nigeria

In silico prediction aided preparation of antioxidant soybean peptides by enzymatic hydrolysis for ameliorating lead exposure-induced toxicity

Food derived bioactive peptides are prominent dietary supplements to protect against oxidative stress induced by lead (Pb) exposure. This study aimed to develop a new strategy for rapid preparation of highly active antioxidant soybean polypeptides (ASPs) against Pb toxicity. In silico enzymatic hydrolysis simulation and antioxidant activity prediction showed that pepsin, chymotrypsin and bromelain can produce peptides with the highest activity. The preparation process was then optimized, and the obtained ASP showed good antioxidant and metal-chelating activities in vitro. An in vivo study showed that ASP exerted prominent protective effects against Pb-induced cognitive impairment and tissue damage in mice by reducing Pb deposition and enhancing the antioxidant capacity in tissues and was superior to Vc, DMSA or their combination in some aspects. ASP composition analysis demonstrated that its prominent antioxidant activity might be attributed to the high proportion of amino acid residues E, L, P and V in the peptide sequence and L, V and A at the C- and N-termini. In conclusion, in silico prediction could facilitate the preparation of ASP. And the ASP prepared with the new strategy exerted prominent protective effects against Pb toxicity.

The deleterious effects of cadmium on oxidative stress markers, drug-metabolizing, and antioxidant enzyme activities: Role of Silymarin and Garlic as Antioxidants

Exposure to cadmium has been related to liver and kidney diseases such as polycystic and nephrotic syndrome. It is still unclear how cadmium contributes to these diseases. It is believed that the induction of oxidative stress resulting from the inhibition of antioxidant enzyme activities and changes in drug-metabolizing enzymes in the liver could explain the role of cadmium in the development of different diseases in the kidney and probably other organs. Changes in oxidative stress markers, antioxidant enzymes, and drug-metabolizing enzyme activities were assessed in the liver of male rats exposed to cadmium chloride. Additionally, the protective effects of silymarin and garlic extract against cadmium toxicosis were evaluated. Rats were randomly divided into eight groups as follows, groups 1, 2, 3, 4, and 5, received orally saline, CdCl2 (1 mg/kg), garlic extract [800 mg/kg], silymarin (25 mg/kg) and silymarin plus garlic extract respectively for 28 consecutive days. Rats in groups 6, 7, and 8 were pretreated with the same doses of garlic, silymarin, and garlic plus silymarin, respectively for two hours before cadmium administration. The Western immunoblotting technique was used to investigate the protein expression of cytochrome P450 isozymes. Spectrophotometric methods were used to assess the activity of both antioxidant- and drug-metabolizing enzymes. Free radical levels [measured as thiobarbituric acid reactive substances (TBARS)], catalase, superoxide dismutase, and glutathione peroxidase activities increased whereas the levels of glutathione and the activities of glutathione S-transferase, glutathione reductase, and glutamyl transferase, cytochrome P450, aryl hydrocarbon dehydrogenase (AHH), dimethylnitrosamine-N-demethylase I (DMN-dI), 7-ethoxycoumarine-O-deethylase (ECOD), cytochrome b5 and NADPH-Cytochrome-c-reductase enzyme activities decreased after cadmium treatment. Furthermore, Western immunoblotting data revealed that glutathione peroxidase protein expression increased following cadmium exposure, but cytochrome P450 2E1 and 3A4 expressions were downregulated. However, pretreatment of rats with silymarin or garlic extract or both before cadmium administration was found to restore the protein expression of cytochrome P450 2E1 and 3A4, the level of free radicals, antioxidant enzymes, drug-metabolizing enzyme activities to their normal levels. Similarly, histological studies revealed that silymarin and/or garlic extract reduced the liver damage caused by cadmium. Silymarin and/or garlic extract reduced the adverse effects of cadmium on the activity of both drug-metabolizing and antioxidant enzymes activity. These antioxidants could be provided to those who work in cadmium-based sectors to help them cope with the adverse effects of cadmium on their kidneys. In addition, Inhibiting drug-metabolizing enzyme activity should be considered when administering therapeutic medications to persons exposed to cadmium because most therapeutic drugs and many endogenous substances are largely metabolized by these enzymes.

Effects of lead and cadmium co-exposure on liver function in residents near a mining and smelting area in northwestern China

Chronic exposure to environmental cadmium (Cd) and lead (Pb) may have adverse effects on the human health. In this study, we aimed to determine the primary and interactive effects of Cd and Pb exposure on liver function in residents near a mining and smelting area in northwestern China. A total of 451 subjects were recruited, from which blood samples were collected to determine the levels of Cd, Pb, and liver function indices. Additionally, the association between the levels of exposure markers and liver function indices was analysed. Cd and Pb levels were significantly higher in subjects living in the polluted area than in those living in the non-polluted reference area. The liver function levels of subjects in the polluted area were poor compared with those in the reference area. In addition, Cd and Pb levels in the blood were positively associated with gamma glutamyl transpeptidase (GGT) levels and negatively associated with direct bilirubin (DBil) levels. Cd and Pb may be risk factors for abnormal liver function. The risk of abnormal liver function was higher in subjects with moderate Cd and Pb levels, high Cd levels, high Pb levels, and high Cd and Pb levels than in those with low Cd and Pb levels. Our data show that exposure to Cd and/or Pb can cause abnormal liver function. Cd and Pb may have an antagonistic effect on liver function, and high Cd exposure alone has a more profound effect on abnormal liver function compared with co-exposure to Pb and Cd.

A new discovery of polystyrene microplastics toxicity: The injury difference on bladder epithelium of mice is correlated with the size of exposed particles

Microplastics (MPs), as widespread hazardous substances in the environment, can cause potential adverse effects on biological health. However, reports on the toxic effects of different diameters MPs on urinary system are limited. Here, we investigated the types and mechanisms of damage to mice bladder epithelial cells treated with diameter (1-10 μm and 50-100 μm) polystyrene microplastics (PS-MPs). The results showed that exposure to PS-MPs of both diameters resulted in necroptosis and inflammation to bladder epithelium. However, 1-10 μm PS-MPs posed more severe necroptosis and 50-100 μm PS-MPs led to a higher degree of inflammatory injury at the same exposure concentration. Mechanistically, PS-MPs were found to induce necroptosis as well as p-NFκB-mediated inflammation by triggering oxidative stress and excessive release of reactive oxygen species (ROS). Furthermore, N-Acetyl-l-cysteine (NAC) attenuated the toxic effects of PS-MPs on bladder epithelial cells. In conclusion, our study demonstrated for the first time that PS-MPs caused necroptosis and inflammation in mice bladders tissues, and the difference of injury correlates with the size of PS-MPs particles.

Prolonged blood coagulation time among occupationally exposed automobile technicians in Abeokuta, Nigeria

Automobile technicians in resource-poor settings often work in poor environments and are exposed to chemicals that put them at risk of ill health and disease. These chemical exposures could affect blood coagulation, leading to bleeding disorders or thrombosis. The present study is aimed at assessing prothrombin test (PT) and activated partial thromboplastin test (aPTT) values, serum zinc (Zn) and copper (Cu) concentrations, and blood lead level (BLL) among occupationally exposed automobile technicians compared to unexposed controls. A total of 140 consenting participants comprising 70 automobile technicians and 70 unexposed controls were recruited for this case-control study. A 6-mL blood sample was drawn from each participant for estimation of BLL, serum Zn and Cu concentrations, and PT and aPTT values. Blood lead level, and serum Zn and Cu concentrations were determined using atomic absorption spectrophotometry, while PT and aPTT values were determined using Innovin PT and Actin FS Activated PTT reagents on the Sysmex CA-101 coagulation analyser. Data were analysed using t-tests, chi-square tests, and logistic and multiple linear regression analyses with statistical significance set at p < 0.05. The mean BLL, serum Zn concentration, and PT and aPTT values were significantly higher in automobile technicians compared to controls. Binary logistic regression showed that automobile technicians had higher odds of elevated PT value (OR = 21.769; p = 0.000), aPTT value (OR = 1.348; p = 0.018), BLL (OR = 1.261; p = 0.000) and serum Zn concentration (OR = 1.063; p = 0.005) than unexposed controls. Linear regression showed significant positive association of PT value with BLL and with serum Zn concentration. Higher PT and aPTT values reflect prolonged blood coagulation time among automobile technicians, which indicates impairment of extrinsic and intrinsic coagulation pathways associated with work-related exposures.

Symptoms Associated with Low Threshold Lead Poisoning Among Roadside and Organized Panel Beaters in Enugu Metropolis, Nigeria

BACKGROUND

There is no safe level of human exposure to lead (Pb). Detecting common early symptoms of low threshold Pb poisoning can help to prevent the damaging effects of higher doses and chronic low dose exposures. Panel beaters or auto body mechanics are exposed to Pb through their occupational duties.

OBJECTIVES

The present study aimed to determine common early symptoms associated with lower threshold Pb poisoning among roadside and organized panel beaters in Enugu Metropolis, Nigeria.

METHODS

This was a comparative cross-sectional study of 428 panel beaters in Enugu metropolis. A multi-stage sampling method was used to select 214 respondents each from the roadside and organized sectors. A semi-structured interviewer-administered questionnaire was used for data collection. Samples were collected under aseptic procedures. Blood Pb samples were extracted using the conventional wet acid digestion method and analyzed using a flame atomic absorption spectrometer (wavelength 283.3 nm). Comparative analysis was performed using the chi - square and Mann-Whitney U test. Statistical significance was set at P < 0.05.

RESULTS

Median Pb levels were 3.0 ug/dL and 16.0 ug/dL among roadside and organized panel beaters, respectively, with a significant difference. Numbness of limbs (P = 0.010) and fatigue (χ² = 5.294, P = 0.023) were found to be associated with roadside panel beaters, while weakness (χ² = 6.185, P = 0.019) and fatigue (χ² = 4.206, P = 0.046) were associated with organized panel beaters.

CONCLUSIONS

Nonspecific constitutional symptoms were common early symptoms of Pb poisoning irrespective of workplace occupational practices. These symptoms will help in early detection and control of occupational lead exposures.

PARTICIPANT CONSENT

Obtained.

ETHICS APPROVAL

Ethics approval was obtained from the Health Research Ethics Committee of the University of Nigeria Teaching Hospital, Ituku Ozalla, Enugu.

COMPETING INTERESTS

The authors declare no competing financial interests.

Back to Nucleus: Combating with Cadmium Toxicity Using Nrf2 Signaling Pathway as a Promising Therapeutic Target

There are concerns about the spread of heavy metals in the environment, and human activities are one of the most important factors in their spread. These agents have the high half-life resulting in their persistence in the environment. So, prevention of their spread is the first step. However, heavy metals are an inevitable part of modern and industrial life and they are applied in different fields. Cadmium is one of the heavy metals which has high carcinogenesis ability. Industrial waste, vehicle emissions, paints, and fertilizers are ways of exposing human to cadmium. This potentially toxic agent harmfully affects the various organs and systems of body such as the liver, kidney, brain, and cardiovascular system. Oxidative stress is one of the most important pathways of cadmium toxicity. So, improving the antioxidant defense system can be considered as a potential target. On the other hand, the Nrf2 signaling pathway involves improving the antioxidant capacity by promoting the activity of antioxidant enzymes such as catalase and superoxide dismutase. At the present review, we demonstrate how Nrf2 signaling pathway can be modulated to diminish the cadmium toxicity.