Copper doping enhanced the oxidative stress-mediated cytotoxicity of TiO2 nanoparticles in A549 cells

Physicochemical properties of titanium dioxide nanoparticles (TiO₂ NPs) can be tuned by doping with metals or nonmetals. Copper (Cu) doping improved the photocatalytic behavior of TiO₂ NPs that can be applied in various fields such as environmental remediation and nanomedicine. However, interaction of Cu-doped TiO₂ NPs with human cells is scarce. This study was designed to explore the role of Cu doping in cytotoxic response of TiO₂ NPs in human lung epithelial (A549) cells. Characterization data demonstrated the presence of both TiO₂ and Cu in Cu-doped TiO₂ NPs with high-quality lattice fringes without any distortion. The size of Cu-doped TiO₂ NPs (24 nm) was lower than pure TiO₂ NPs (30 nm). Biological results showed that both pure and Cu-doped TiO₂ NPs induced cytotoxicity and oxidative stress in a dose-dependent manner. Low mitochondrial membrane potential and higher caspase-3 enzyme (apoptotic markers) activity were also observed in A549 cells exposed to pure and Cu-doped TiO₂ NPs. We further observed that cytotoxicity caused by Cu-doped TiO₂ NPs was higher than pure TiO₂ NPs. Moreover, antioxidant N-acetyl cysteine effectively prevented the reactive oxygen species generation, glutathione depletion, and cell viability reduction caused by Cu-doped TiO₂ NPs. This is the first report showing that Cu-doped TiO₂ NPs induced cytotoxicity and oxidative stress in A549 cells. This study warranted further research to explore the role of Cu doping in toxicity mechanisms of TiO₂ NPs.

Rotenone-induced oxidative stress and apoptosis in human liver HepG2 cells

Rotenone, a commonly used pesticide, is well documented to induce selective degeneration in dopaminergic neurons and motor dysfunction. Such rotenone-induced neurodegenration has been primarily suggested through mitochondria-mediated apoptosis and reactive oxygen species (ROS) generation. But the status of rotenone induced changes in liver, the major metabolic site is poorly investigated. Thus, the present investigation was aimed to study the oxidative stress-induced cytotoxicity and apoptotic cell death in human liver cells-HepG2 receiving experimental exposure of rotenone (12.5-250 μM) for 24 h. Rotenone depicted a dose-dependent cytotoxic response in HepG2 cells. These cytotoxic responses were in concurrence with the markers associated with oxidative stress such as an increase in ROS generation and lipid peroxidation as well as a decrease in the glutathione, catalase, and superoxide dismutase levels. The decrease in mitochondrial membrane potential also confirms the impaired mitochondrial activity. The events of cytotoxicity and oxidative stress were found to be associated with up-regulation in the expressions (mRNA and protein) of pro-apoptotic markers viz., p53, Bax, and caspase-3, and down-regulation of anti-apoptotic marker Bcl-2. The data obtain in this study indicate that rotenone-induced cytotoxicity in HepG2 cells via ROS-induced oxidative stress and mitochondria-mediated apoptosis involving p53, Bax/Bcl-2, and caspase-3.

Environmental lead exposure as a risk for childhood aplastic anemia

Concern about environmental lead exposure as a significant public health threat has increased as evidence has accumulated regarding adverse health effects at successively lower levels. Aplastic anemia is a hematological disorder of unknown etiology with a high lethality rate. Lead is a known toxicant for the hematopoietic system. Oxidative stress appears to be the possible mode of lead toxicity. We evaluated the effects of blood lead level on oxidative stress parameters in children suffering from aplastic anemia disease. Seventeen children with aplastic anemia disease (15 male and 2 female, age 3-12 y) were recruited in the study group. Fifty one healthy children (45 male and 6 female, age 3-12 y) having normal blood profiles and not suffering from any chronic disease(s) were used as controls. Blood lead level and oxidative stress parameters were determined. Mean blood lead level was significantly higher while δ-aminolevulinic acid dehydratase (δ-ALAD) activity, a biomarker for lead exposure was significantly lower in the study group as compared to the control group (p < 0.05 for each). Thiobarbituric acid reactive species (TBARS), a marker of lipid peroxidation, was significantly higher while the antioxidant glutathione (GSH) level was significantly lower in the study group as compared to the control group (p < 0.05 for each). Activity of the antioxidant enzyme catalase (CAT) was significantly higher in the study group than in the control group (p < 0.05). There was a significant negative correlation of blood lead levels with δ-ALAD (r = -0.45; p < 0.05) and GSH (r = -0.32; p < 0.05), and a positive correlation with TBARS (r = 0.41; p < 0.05) and CAT (r = 0.37; p < 0.05). Although a causal pathway cannot be determined from this study, our results indicated that lead induces oxidative stress in children suffering from aplastic anemia. Lead-induced oxidative stress as an underlying mechanism for aplastic anemia warrants further research.

Effect of Trans-resveratrol on Rotenone-induced Cytotoxicity in Human Breast Adenocarcinoma Cells

Rotenone, a botanical insecticide is known to cause apoptosis in various cell types. Trans-resveratrol, a natural phytophenol present in red grapes and wine, is also well documented for its antioxidant, anti-inflammatory, anti-mutagenic, and anticarcinogenic activities. Therefore, the present investigations were carried out to assess the protective effect of trans-resveratrol against rotenone-induced cell death in human breast adenocarcinoma (MCF-7) cells. MCF-7 cells were exposed with various concentrations of rotenone for 24 h, and the loss in percent cell viability was evaluated by MTT [3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide] and neutral red uptake (NRU) assays. A significant decrease in percent cell viability in MCF-7 cells was observed at 50 μM and above concentrations of rotenone, as compared to untreated control. Furthermore, various concentrations (5, 10, and 25 μM) of trans-resveratrol were used to see its protective role on cell viability in rotenone-induced cell death in MCF-7 cells. Pre- or post- treatment of trans-resveratrol for 24 h was given to the cells. The data exhibited a significant dose dependent increase in the percent cell viability under pre- and post-treatment conditions. However, post-treatment of trans-resveratrol for 24 h after rotenone exposure to the cells was relatively less effective. Overall, the results suggest that trans-resveratrol significantly protects MCF-7 cells from rotenone-induced cell death. This model can be used as an effective and economical alternative to animal models for screening the antioxidant activity of a variety of natural compounds/drugs.

Low level lead exposure and oxidative stress: Current opinions

Lead continues to pose a serious threat to the health of many children as well as adults. Concern about lead exposure as a significant public health problem has increased as evidence has mounted regarding adverse health effects at successively lower levels. This issue is complicated by the fact that there is no demonstrated biological function of lead in human. Lead potentially induces oxidative stress and evidence is accumulating to support the role of oxidative stress in the pathophysiology of lead toxicity. Lead is capable of inducing oxidative damage to brain, heart, kidneys, and reproductive organs. The mechanisms for lead-induced oxidative stress include the effects of lead on membranes, DNA, and antioxidant defense systems of cells. Recent epidemiological and toxicological studies have reported that lead exposure causes several diseases including hypertension, kidney disease, neurodegenerative disease and cognitive impairment. Although all these diseases include components of oxidative stress, the relevance of oxidative stress to lead-related diseases with low lead exposure has been criticized because most of the mechanistic studies have been conducted at moderate to higher dose levels. The association between low level lead exposure and oxidative stress has not been explored systematically. The present review focuses on mechanisms for lead-induced oxidative stress and relevance of oxidative stress to lead-related human disease with low lead exposure.

Interaction of lead with some essential trace metals in the blood of anemic children from Lucknow, India

BACKGROUND

The effects of lead on the hematological system results in the inhibition of heme synthesis and in anemia. Lead may affect the absorption and metabolism of essential trace metals also. There is little information especially from the northern region of India regarding the relationship between blood lead levels>or=10 microg/dl and anemia in children. We performed a cross-sectional study to evaluate the association of blood lead levels>or=10 microg/dl with anemia, and its effect on hematological system and some essential trace metals in children.

METHODS

A total of 75 children aged 1-7 years, 50 anemic (Hb<or=8 g%) and 25 non-anemic (Hb>8 g%), drawn from Lucknow, India and nearby areas were recruited to determine blood levels of lead, iron, zinc, copper, and calcium along with hematological parameters [delta-aminolevulinic acid dehydratase (delta-ALAD) hemoglobin (Hb), hematocrit, and ascorbic acid].

RESULTS

Based on Centre for Disease Control and Prevention's intervention level of blood lead, children were categorized into those with blood lead<10 microg/dl (6.89+/-2.44) (n=19) (GI) and those with blood lead<10 microg/dl (21.86+/-7.58) (n=56) (GII). After adjustment for child's age, sex, and area of residence, children with blood lead levels>or=10 microg/dl were 2.87 (95% CI: 1.60-2.87) times as likely to have anemia as children with blood lead levels<10 microg/dl. The differences of the adjusted mean values of Hb, delta-ALAD, and hematocrit were significantly lower in children from the GII group when compared to children from the GI group (p<0.01, p<0.01, and p<0.05, respectively). Among essential trace metals, adjusted mean levels of blood iron, zinc, and calcium were significantly lower in GII as compared to GI (P<0.05 each). There were significant negative correlations of blood lead levels with delta-ALAD (r=-0.612, p<0.01), hematocrit (r=-0.427, p<0.05), iron (r=-0.552, p<0.05) zinc (r=-0.427, p<0.05), and calcium (r=-0.324, p<0.05).

CONCLUSION

Results indicate that elevated blood lead levels (>or=10 microg/dl) in children were significantly associated with risk of anemia and that blood lead levels also influenced the status of essential trace metals. However, results of this study may be limited due to limited sample size but certainly form the basis of a larger sample size study, taking into account all the known potential confounders of anemia in children.

Delta-aminolevulinic acid dehydratase inhibition and oxidative stress in relation to blood lead among urban adolescents

To explore lead-induced oxidative stress among urban adolescents, the present study, the first from India, was designed to determine the proportion of urban adolescents with blood lead >10 microg/dL and its impact on selected oxidative stress parameters and delta-aminolevulinic acid dehydratase (delta-ALAD) inhibition, which could be used as biomarkers of lead intoxication. A total of 39, urban, male adolescents, drawn from Lucknow and adjoining areas, were recruited to determine lead, delta-ALAD, malondialdehyde (MDA) and glutathione (GSH) in blood and catalase (CAT) in RBCs. Mean level of blood lead was 9.96 +/- 3.63 microg/dL (4.62-18.64); 43% of adolescents crossed the Centre for Disease Control (CDC) intervention level of 10 pg/dL blood lead. On the basis of blood lead levels (BLLs), adolescents were categorized into two groups: Group I and Group II had a blood lead <10 microg/dL (7.40 +/- 1.62) and >10 microg/dL (13.27 +/- 2.67), respectively, with significantly different mean values (P <0.001). Age, sex, body mass index (BMI), Hb level (malnutrition), and area of living as confounders of lead exposure and toxicity were not statistically different between the two groups. However, delta-ALAD activity was significantly lower (P <0.001), while CAT activity was higher in Group II than in Group I (P <0.01). MDA level was also significantly higher in Group II compared to Group I (P <0.001). There were significant negative correlation of BLL with 6-ALAD (r= -0.592, P <0.001), and positive correlations with CAT (r=0.485, P <0.01) and MDA (r=0.717, P <0.001). Interestingly, delta-ALAD, in turn, had significant negative correlations with CAT (r= -0.456, P <0.01) and MDA (r= -0.507, P <0.01). Results of the present pilot study provide clues to the possible low level of lead-induced oxidative stress in urban adolescents, suggesting that lead-induced 6-ALAD inhibition can also be an indicator of oxidative stress. The potential of oxidative stress parameters to be used as biomarkers of lead toxicity warranted further investigation.

Childhood aplastic anaemia in Lucknow, India: Incidence, organochlorines in the blood and review of case reports following exposure to pesticides

OBJECTIVES

A hospital-based case-control study, the first in India, was conducted to determine the incidence of childhood aplastic anaemia in and around Lucknow in the backdrop of organochlorine levels in the blood and review the database for any association between the disease and exposure to pesticides.

DESIGN AND METHODS

A total of 25 cases of childhood aplastic anaemia were identified as per established criteria and enrolled over the study period of 1 year. Their blood organochlorine levels were determined using a gas-liquid chromatograph equipped with an electron capture detector.

RESULTS

The annual incidence of childhood aplastic anaemia in and around Lucknow was found to be 6.8 cases per million which is higher than many countries (e.g., France, Brazil, UK, and United States) but lower than those reported in Sweden, China and an European-Israeli collaborative study. Blood levels of alpha-HCH, gamma-HCH, delta-HCH, total-HCH, and p, p'-DDE were higher in children with aplastic anaemia than in those of controls; only alpha-HCH differed significantly (P < 0.05).

CONCLUSIONS

Although this pilot study, with limited statistical power, did not support any association between exposure to organochlorines and risk of childhood aplastic anaemia, a possible association between the two could not be ruled out in view of several cases identified following exposure to pesticides.

Environmental exposure to lead and its correlation with biochemical indices in children

Lead is a global concern because of its ubiquity in the environment and known to be associated with abnormal neurobehavioral and cognitive development of young children. There is no study from India to describe a composite profile of blood lead and its biochemical influences in children. The present study was aimed at determining the proportion of children with >10 mug/dL blood lead levels (BLLs), association between BLLs, and sociodemographic characteristics, if any, and alterations in biochemical indices in the blood as an underlying mechanism of lead intoxication. A total of 62 children (4--12 y) of Lucknow and nearby areas were recruited to determine BLLs, delta-amimolevulinic acid dehydratase (delta-ALAD) activity, catalase (CAT) activity, and malondialdehyde (MDA) and glutathione (GSH) levels in the blood. Mean level of blood lead was 7.47+/-3.06 microg/dL (2.78--15.0) and 29%-exceeded 10 microg/dL, CDC intervention level. The BLLs were found to be significantly influenced by social status, area of residence, source of water supply, maternal educational status (p<0.001), type of house, and proximity to traffic density (p<0.01). delta-ALAD was significantly lower in the group of children with BLLs 11.39+/-1.39 microg/dL when compared to children with BLLs 7.11+/-1.25 microg/dL and 3.93+/-0.61 microg/dL (p=0.0007, 0.0005, respectively). However, CAT activity was higher in the groups of children with higher blood levels than with lower BLLs (p=0.0159, 0.0001, respectively). There was an increase in MDA level with a concomitant decrease of GSH in children with BLLs 11.39+/-1.39 microg/dL compared with those of children with BLLs 7.11+/-1.25 microg/dL and 3.93+/-0.61 microg/dL (p=0.0001, 0.0002, and p=0.0001, respectively). There was statistically significant correlation of BLLs with delta-ALAD (r=-0.44, p=0.00035), MDA (r=0.46, p=0.00018), GSH (r=-0.62, p=0.00001), and CAT (r=0.44, p=0.00035). Significantly, CAT activity, MDA, and GSH levels were in turn, found to be correlated with delta-ALAD (r=-0.45, p=0.00024; r=-0.43, p=0.00053; r=0.43, p=0.00053, respectively). Results of the present study indicate a declining trend of BLLs in children when compared with those reported from metropolitan cities of India when leaded gasoline was in practice and that the BLLs were significantly associated with biochemical indices in the blood which have the potential to be used as biomarkers of lead intoxication.