Evaluation of oxidative stress and genotoxicity in organophosphorus insecticide formulators

Genetic variation in base excision repair pathway genes, pesticide exposure, and prostate cancer risk

BACKGROUND

Previous research indicates increased prostate cancer risk for pesticide applicators and pesticide manufacturing workers. Although underlying mechanisms are unknown, evidence suggests a role of oxidative DNA damage.

OBJECTIVES

Because base excision repair (BER) is the predominant pathway involved in repairing oxidative damage, we evaluated interactions between 39 pesticides and 394 tag single-nucleotide polymorphisms (SNPs) for 31 BER genes among 776 prostate cancer cases and 1,444 male controls in a nested case-control study of white Agricultural Health Study (AHS) pesticide applicators.

METHODS

We used likelihood ratio tests from logistic regression models to determine p-values for interactions between three-level pesticide exposure variables (none/low/high) and SNPs (assuming a dominant model), and the false discovery rate (FDR) multiple comparison adjustment approach.

RESULTS

The interaction between fonofos and rs1983132 in NEIL3 [nei endonuclease VIII-like 3 (Escherichia coli)], which encodes a glycosylase that can initiate BER, was the most significant overall [interaction p-value (pinteract) = 9.3 × 10-6; FDR-adjusted p-value = 0.01]. Fonofos exposure was associated with a monotonic increase in prostate cancer risk among men with CT/TT genotypes for rs1983132 [odds ratios (95% confidence intervals) for low and high use compared with no use were 1.65 (0.91, 3.01) and 3.25 (1.78, 5.92), respectively], whereas fonofos was not associated with prostate cancer risk among men with the CC genotype. Carbofuran and S-ethyl dipropylthiocarbamate (EPTC) interacted similarly with rs1983132; however, these interactions did not meet an FDR < 0.2.

CONCLUSIONS

Our significant finding regarding fonofos is consistent with previous AHS findings of increased prostate cancer risk with fonofos exposure among those with a family history of prostate cancer. Although requiring replication, our findings suggest a role of BER genetic variation in pesticide-associated prostate cancer risk.

Genetic variation in nucleotide excision repair pathway genes, pesticide exposure and prostate cancer risk

Previous research demonstrates increased prostate cancer risk for pesticide applicators and pesticide manufacturing workers. Although underlying mechanisms are unknown, human biomonitoring studies indicate increased genetic damage (e.g. chromosomal aberrations) with pesticide exposure. Given that the nucleotide excision repair (NER) pathway repairs a broad range of DNA damage, we evaluated interactions between pesticide exposure and 324 single-nucleotide polymorphisms (SNPs) tagging 27 NER genes among 776 prostate cancer cases and 1444 male controls in a nested case-control study of white Agricultural Health Study pesticide applicators. We determined interaction P values using likelihood ratio tests from logistic regression models and three-level pesticide variables (none/low/high) based on lifetime days of use weighted to an intensity score. We adjusted for multiple comparisons using the false discovery rate (FDR) method. Of the 17 interactions that met FDR <0.2, 3 displayed a monotonic increase in prostate cancer risk with increasing exposure in one genotype group and no significant association in the other group. Men carrying the variant A allele at ERCC1 rs2298881 exhibited increased prostate cancer risk with high versus no fonofos use [odds ratio (OR) 2.98; 95% confidence interval (CI) 1.65-5.39; P(interact) = 3.6 × 10(-4); FDR-adjusted P = 0.11]. Men carrying the homozygous wild-type TT genotype at two correlated CDK7 SNPs, rs11744596 and rs2932778 (r(2) = 1.0), exhibited increased risk with high versus no carbofuran use (OR 2.01; 95% CI 1.31-3.10 for rs11744596; P(interact) = 7.2 × 10(-4); FDR-adjusted P = 0.09). In contrast, we did not observe associations among men with other genotypes at these loci. While requiring replication, our findings suggest a role for NER genetic variation in pesticide-associated prostate cancer risk.

Influence of CYP2C9, GSTM1, GSTT1 and NAT2 genetic polymorphisms on DNA damage in workers occupationally exposed to organophosphate pesticides

Previous studies have revealed that organophosphate pesticides (OPs) are primarily metabolized by xenobiotic metabolizing enzymes (XMEs). Very few studies have explored genetic polymorphisms of XMEs and their association with DNA damage in pesticides-exposed workers. Present study was designed to determine the influence of CYP2C9, GSTM1, GSTT1 and NAT2 genetic polymorphisms on DNA damage in workers occupationally exposed to OPs. We examined 268 subjects including 134 workers occupationally exposed to OPs and an equal number of normal healthy controls. The DNA damage was evaluated using alkaline comet assay and genotyping was done using individual polymerase chain reaction (PCR) or polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Acetylcholinesterase and paraoxonase activity were found to be significantly lowered in workers as compared to control subjects which were analyzed as biomarkers of toxicity due to OPs exposure (p<0.001). Workers showed significantly higher DNA tail moment (TM) compared to control subjects (14.32±2.17 vs. 6.24±1.37 tail % DNA, p<0.001). GSTM1 null genotype was found to influence DNA TM in workers (p<0.05). DNA TM was also found to be increased with concomitant presence of NAT2 slow acetylation and CYP2C9*3/*3 or GSTM1 null genotypes (p<0.05). DNA TM was found increased in NAT2 slow acetylators with mild and heavy smoking habits in control subjects and workers, respectively (p<0.05). The results of this study suggest that GSTM1 null genotypes, and an association of NAT2 slow acetylation genotypes with CYP2C9*3/*3 or GSTM1 null genotypes may modulate DNA damage in workers occupationally exposed to OPs.

Biochemical evidence on the potential role of organophosphates in hepatic glucose metabolism toward insulin resistance through inflammatory signaling and free radical pathways

Several studies show that organophosphate pesticides exert several effects on glucose homeostasis. The current study investigates the influence of subchronic exposure to malathion (MT) on hepatic gluconeogenesis in relation to acetyl cholinesterase (AChE) inhibition, oxidative stress and inflammatory response in the rat. MT was administered by gavage at doses of 25, 50 and 100 mg/kg for 32 days. Fasting hyperglycemia was seen in line with an increased activity of hepatic phosphoenolpyruvate carboxykinase, glucose 6-phosphatase and tumor necrosis factor α. In addition to the impaired glucose tolerance and inhibition of AChE in a dose-dependent manner, there were significant increases in hepatic lipid peroxidation, carbonyl groups and 8-deoxyguanosine as the biomarkers of reactive oxygen species–mediated damage to lipid, protein and DNA, respectively. Altered quality of the liver in glucose production especially gluconeogenesis could be a compensatory mechanism against MT toxicity or even result in tissue damage. MT-induced insulin resistance in the liver occurs through oxidative and inflammatory signaling pathways.

Malathion and fenvalerate induce micronuclei in mouse bone marrow cells

Health effects of pesticides are a major public health concern. In this study, the genotoxic effects of two commonly-used pesticides, malathion, and fenvalerate, were investigated in mice in vivo. Induction of micronuclei in bone marrow cells was used as the test parameter following exposure to 2.5, 5 or 10 mg/kg malathion by intraperitoneal (i.p.) or per oral (p.o.) exposure. Exposure by both routes was found to cause a significant increase in micronucleated polychromatic erythrocytes (PCEs) in a dose-dependent manner (r = 0.9769; P < 0.05). The highest dose (10 mg/kg) induced significant (P < 0.05) cytotoxicity. In contrast, fenvalerate caused an increase in micronucleated PCEs only at higher doses (10 and 20 mg/kg) via i.p. injection, and was not associated with cytotoxicity. A significant dose-response correlation was not observed in the dose ranges tested for fenvalerate (r = 0.8704; P > 0.05). The results suggest that technical grade malathion is a genotoxic agent. In contrast, technical grade fenvalerate appears to be a potent genotoxic agent, but this observation should be confirmed with further investigation(s).

Role of genetic polymorphisms of CYP1A1, CYP3A5, CYP2C9, CYP2D6, and PON1 in the modulation of DNA damage in workers occupationally exposed to organophosphate pesticides

Organophosphate pesticides (OPs) are primarily metabolized by several xenobiotic metabolizing enzymes (XMEs). Very few studies have explored genetic polymorphisms of XMEs and their association with DNA damage in pesticide-exposed workers. The present study was designed to determine the role of genetic polymorphisms of CYP1A1, CYP3A5, CYP2C9, CYP2D6, and PON1 in the modulation of DNA damage in workers occupationally exposed to OPs. We examined 284 subjects including 150 workers occupationally exposed to OPs and 134 normal healthy controls. The DNA damage was evaluated using the alkaline comet assay and genotyping was done using PCR-RFLP. The results revealed that the PONase activity toward paraoxonase and AChE activity was found significantly lowered in workers as compared to control subjects (p<0.001). Workers showed significantly higher DNA damage compared to control subjects (14.37±2.15 vs. 6.24±1.37 tail% DNA, p<0.001). Further, the workers with CYP2D6*3PM and PON1 (QQ and MM) genotypes were found to have significantly higher DNA damage when compared to other genotypes (p<0.05). In addition, significant increase in DNA damage was also observed in workers with concomitant presence of certain CYP2D6 and PON1 (Q192R and L55M) genotypes which need further extensive studies. In conclusion, the results indicate that the PON1 and CYP2D6 genotypes can modulate DNA damage elicited by some OPs possibly through gene-environment interactions.

Effects of the organophosphate insecticide azinphos-methyl on the reproduction and cholinesterase activity of Biomphalaria glabrata

Azinphos-methyl is an organophosphate insecticide used for pest control on a number of food crops in many parts of the world. The snail Biomphalaria glabrata is a freshwater gastropod widely distributed in South America, Central America and Africa. The aim of the present work was to investigate whether azinphos-methyl causes alterations in the reproduction of B. glabrata. To this end, gastropod pigmented specimens were exposed to various concentrations of the insecticide (0.021, 0.5, 2.5, and 5 mg L(-1)) for either 2 or 14 d. Along 14 d, several reproduction parameters and cholinesterase (ChE) activity were evaluated. In each group, the number of egg masses, the number of eggs per mass, the number of hatchings, the time to hatching, and the survival of the offspring after one month of treatment was evaluated. The results showed that, depending on the concentration and time of exposure, azinphos-methyl induced alterations in the reproduction of B. glabrata. These alterations were mainly represented by a decrease in the number of egg masses, and, in some cases, by a lower number or even the total absence of hatchings. Thus, the gastropods exposed to 2.5 and 5 mg L(-1) of azinphos-methyl for 14 d showed ChE inhibitions higher than 35% along time and completely lost their ability to reproduce. On the other hand, exposure to high acute concentrations or exposure to low concentrations for 14 d resulted in ChE inhibition equal to or lower than 35% between 7 and 14 d of treatment and similar alterations in reproduction. These were represented by a decrease in the number of egg masses. At low pestice levels, the number of egg masses and the number of offspring resulted to be more sensitive biomarkers than ChE inhibition. It is concluded that the insecticide azinphos-methyl can cause a decline in the reproductive performance of B. glabrata.

Genetic polymorphisms of GSTM1, GSTT1 and GSTP1 and susceptibility to DNA damage in workers occupationally exposed to organophosphate pesticides

GSTM1, T1 and P1 are important enzymes of glutathione S-transferases (GSTs), involved in the metabolism of many endogenous and exogenous compounds. Individual genetic variation in these metabolizing enzymes may influence the metabolism of their substrates. The present study was designed to determine the genotoxic effects using DNA damage and its association with GSTM1, GSTT1, and GSTP1 (Ile105Val) genetic polymorphisms in workers occupationally exposed to organophosphate pesticides (OPs). We examined 230 subjects including 115 workers occupationally exposed to OPs and an equal number of normal healthy controls. The DNA damage was evaluated using the alkaline comet assay and genotyping was done using individual PCR or PCR-RFLP. Significantly higher DNA tail moment (TM) was observed in workers as compared to control subjects (14.41 ± 2.25 vs. 6.36 ± 1.41 tail % DNA, p<0.001). The results revealed significantly higher DNA TM in workers with GSTM1 null genotype than those with GSTM1 positive (15.18 vs. 14.15 tail % DNA, p=0.03). A significantly higher DNA TM was also observed in workers with homozygous Ile-Ile GSTP1 genotype than heterozygous (Ile-Val) and mutant (Val-Val) GSTP1 genotype (p=0.02). In conclusion, the results show that null deletion of GSTM1 and homozygote wild GSTP1 genotype could be related to inter-individual differences in DNA damage arises from the gene-environment interactions in workers occupationally exposed to OPs.

Electroencephalogram, cognitive state, psychological disorders, clinical symptom, and oxidative stress in horticulture farmers exposed to organophosphate pesticides

The aim of this paper was to study the toxicity of organophosphate (OP) pesticides in exposed farmers for electroencephalography, cognitive state, psychological disorders, clinical symptom, oxidative stress, acetylcholinesterase, and DNA damage. A comparative cross-sectional analysis was carried out in 40 horticulture farmers who were exposed to OPs in comparison to a control group containing 40 healthy subjects with the same age and sex and education level. Lipid peroxidation (LPO), superoxide dismutase (SOD), catalase, glutathione peroxidase, DNA damage, total antioxidant capacity (TAC), total thiol molecules, and acetylcholinesterase (AChE) activity were measured in the blood of subjects. Clinical examination and complete blood test were undertaken in order to record any abnormal sign or symptoms. Cognitive function, psychological symptoms, and psychological distress were examined and recorded. Comparing with controls, the farmers showed higher blood levels of SOD and LPO while their TAC decreased. Farmers showed clinical symptoms such as eczema, breathing muscle weakness, nausea, and saliva secretion. Regarding cognitive function, the orientation, registration, attention and calculation, recall, and language were not significantly different in farmers and controls. Among examinations for psychological distress, only labeled somatization was significantly higher in farmers. The present findings indicate that oxidative stress and inhibition of AChE can be seen in chronically OP-exposed people but incidence of neuropsychological disorders seems a complex multivariate phenomenon that might be seen in long-term high-dose exposure situations. Use of supplementary antioxidants would be useful in the treatment of farmers.

Genotoxicity in agricultural farmers from Guntur district of South India—A case study

Background: Pesticides play an important role in controlling the pests on agricultural crops and thereby to increase the yield of agricultural produce. Farmers occupationally exposed to pesticides during spraying activities are more prone to genotoxicity than unexposed. Aim: To assess the genotoxicity in farmers, engaged in spraying complex mixture of pesticides in the cultivation of cotton crops. Material and methods: A total number of 152 male subjects were selected randomly from Guntur district of Andhra Pradesh (AP), South India. The demographic particulars viz., personal habits, duration of exposure to pesticides, types of pesticides used were collected from the study subjects using an interview schedule. Among them 76 subjects were farmers and the remaining individuals served as unexposed or controls. Blood samples from these subjects were collected for assessing the genetic damage by chromosomal aberrations (CAs) test and micronucleus test (MNT). Results: The results of the study indicated that CA was significantly higher with 2.8% in farmers who were exposed to pesticides when compared to unexposed (0.72%). However, there was a minor difference in MN with 0.13% and 0.12% between exposed and unexposed which was not statistically significant ( p < 0.05). Conclusion: A correlation between CA frequency and exposure to benzene hexachloride (BHC) pesticide residue was observed.

Oxidative stress in the blood of farm workers following intensive pesticide exposure

The aim of this study was to evaluate oxidative stress in workers who formulate organophosphate, synthetic pyrethroid and carbamate pesticides. In this survey, blood erythrocytes from a group of 94 pesticide-formulating workers (at least 5-years experience in pest-control in apple and cherry production) and 45 control subjects were examined for oxidative stress parameters. The control group was composed of 45 healthy people living in the same region with no exposure to pesticides. Lipid peroxidation level, catalase, superoxide dismutase and glutathione peroxidase activities in erythrocytes were analysed as biomarkers of oxidative stress. In addition, the acetylcholinesterase activity was measured as a biomarker of toxicity. Results indicated that chronic exposure to organophosphate, synthetic pyrethroid and carbamate pesticides were associated with increased activities of catalase, SOD and lipid peroxidation in erythrocytes (p < 0.05). Acetylcholinesterase activity did not show any significant differences between the two groups (p > 0.05). It is concluded that human chronic exposure to pesticides may result in stimulated antioxidant enzymes.

DNA damage and cholinesterase activity in occupational workers exposed to pesticides

The present study was designed to evaluate genotoxicity, acetyl cholinesterase (AChE) activity, hepatic and renal toxicity in occupational workers exposed to mixture of pesticides (n=70) with same number of healthy subjects as controls. The mean comet tail DNA % (TD %) and tail moment (TM) were used to measure DNA damage, while AChE activity and other biochemical parameters such as markers of nephrotoxicity (urea and creatinine) and hepatotoxicity (AST, ALT and ALP) were measured as biomarkers for toxicity due to exposure of pesticides. The occupational workers were continuously exposed to mixture of pirimiphos methyl, chlorpyrifos, temephos and malathion on a regular interval as per usage and activity. The comet assay using lymphocytes of exposed workers showed significantly higher TD percentage value (60.43% vs. 31.86%, p<0.001) and TM value (14.48 μm vs. 6.42 μm, p<0.001) in occupational workers as compared to controls. AChE activity in erythrocytes was found to be decreased (3.45 KAU/L vs. 9.55 KAU/L in controls, p<0.001) and associated with the duration of exposure to pesticides used by the workers. Enzyme levels for hepatic and renal functions were also found significantly different in occupational workers than healthy controls (p<0.001). These results suggest that the exposure to mixture of pirimiphos methyl, chlorpyrifos, temephos and malathion may induce DNA damage, decrease in AChE activity, hepatotoxicity as well as nephrotoxicity. Periodic biomonitoring of these biomarkers along with imparting education and training to occupational workers for safe application of pesticides is recommended for its potential hazards.

Benefit of nanocarrier of magnetic magnesium in rat malathion-induced toxicity and cardiac failure using non-invasive monitoring of electrocardiogram and blood pressure

Medical management in acute organophosphate (OP) poisoning is not always successful because of tissue hypoxia which results in a reduction of heart contractility and cell damage. This study reports improvement of malathion (MAL)-induced cardiac failure by a nanocarrier of magnetic isotope of Mg (PMC16). A rat model of acute MAL poisoning was set up. PMC16 nanoparticle at doses of 0.05, 0.1, 0.2 LD50 = 896 mg/kg) were administered intravenously (iv) 30 minutes after a single intraperitoneal (ip) injection of MAL (0.25 LD50= 207 mg/kg). Atropine (AT; 40 mg/kg, ip) plus pralidoxime (PAM; 40 mg/kg, ip) and magnesium sulfate (MgSO₄; 600 mg/kg, iv) were used as standard therapy or controls. Anesthetized animals were monitored for heart rate, electrocardiogram, blood pressure, and blood oxidative stress biomarkers like cellular lipid peroxidation, total thiol molecules, antioxidant power, gamma glutamil transpeptidase, and acetylcholinesterase (AChE) as a marker of OP toxicity. Results indicated that after MAL administration, heart rate and BP decreased and R-R duration increased. PMC16 markedly restored BP at all doses as compared with MgSO₄. PMC16 at the dose of 0.05 LD50 significantly increased BP in comparison to AT + PAM. PMC16 restored heart rate at dose of 0.2 LD50 and reduced lipid peroxidation at dose of 0.05 LD50 as compared to MgSO₄. PMC16 also improved total antioxidant power at all doses when compared to AT + PAM and reduced GGT activity at dose of 0.2 LD50 but did not affect total thiol molecules. MgSO₄ could improve MAL-induced reduction of total antioxidant power. After 24 h, PMC16 significantly improved MAL-suppressed AChE activity at doses of 0.05 and 0.1 LD50. PMC16 at all doses significantly recovered MAL-induced arrhythmia when compared to standard therapies. It is concluded that PMC16 is able to control OP-induced cardiac failure and toxicity.

Bilateral loculated pleural effusion as a manifestation of acute parenteral organophosphate intoxication: a case report

BACKGROUND

Acute organophosphate (OP) toxicity causes a wide range of clinical effects on the respiratory system, including pulmonary bronchoconstriction and bronchorrhea. Morbidity and mortality from acute OP toxicity correlate best with pulmonary secretions.

OBJECTIVE

In this article, we report bilateral loculated pleural effusion as a rare pulmonary effect in a patient with acute parenteral OP toxicity.

CASE REPORT

A 25-year-old, previously healthy woman was transferred to our Poison Department 3 days after suicidal injection of malathion. At the time of presentation her vital signs were normal, except that her respiratory rate was 24 breaths/min. She complained of pleuritic chest pain and had a cough productive of yellow sputum. She had generalized chest wall tenderness, and breath sounds were decreased in the base of both lung fields. Standard therapy for OP toxicity, including atropine, pralidoxime, and diazepam, was initiated. Due to persistent pleuritic chest pain, a computed tomography (CT) scan was performed that showed bilateral loculated pleural effusions. Shortly after hospital admission, the patient developed respiratory distress, for which she was intubated and transferred to the Intensive Care Unit. She received continued medical therapy and was extubated on hospital day 3. A CT scan of the chest on hospital day 9, after completion of the treatment, documented resolution of the effusions.

CONCLUSION

Parenteral OP toxicity occurs rarely, and in this case it was associated with bilateral loculated pleural effusions. In this regard, it should be considered in a patient with acute parenteral OP toxicity and persistent chest wall pain.

Correlating neurobehavioral performance with biomarkers of organophosphorous pesticide exposure

There is compelling evidence that adverse neurobehavioral effects are associated with occupational organophosphorous pesticide (OP) exposure in humans. Behavioral studies of pesticide applicators, greenhouse workers, agricultural workers and farm residents exposed repeatedly over months or years to low levels of OPs reveal a relatively consistent pattern of neurobehavioral deficits. However, only two studies have demonstrated a link between neurobehavioral performance and current biomarkers of OP exposure including blood cholinesterase (ChE) activity and urinary levels of OP metabolites. A variety of reasons may explain why so few studies have reported such correlations, including differing individual and group exposure histories, differing methodologies for assessing behavior and exposure, and lack of a reliable index of exposure. Alternatively, these data may suggest that current biomarkers (ChE, urine metabolites) are neither predictive nor diagnostic of the neurobehavioral effects of chronic OP pesticide exposures. This review focuses on the evidence that neurobehavioral performance deficits are associated with occupational OP pesticide exposure and concludes that research needs to return to the basics and rigorously test the relationships between neurobehavioral performance and both current (ChE and urine metabolites) and novel (e.g., inflammation and oxidative stress) biomarkers using human and animal models. The results of such studies are critically important because OP pesticides are widely and extensively used throughout the world, including situations where exposure controls and personal protective equipment are not routinely used.

Toxic influence of organophosphate, carbamate, and organochlorine pesticides on cellular metabolism of lipids, proteins, and carbohydrates: a systematic review

Pesticides, including organophosphate (OP), organochlorine (OC), and carbamate (CB) compounds, are widely used in agricultural and indoor purposes. OP and CB act as acetyl cholinesterase (AChE) inhibitors that affect lots of organs such as peripheral and central nervous systems, muscles, liver, pancreas, and brain, whereas OC are neurotoxic involved in alteration of ion channels. There are several reports about metabolic disorders, hyperglycemia, and also oxidative stress in acute and chronic exposures to pesticides that are linked with diabetes and other metabolic disorders. In this respect, there are several in vitro and in vivo but few clinical studies about mechanism underlying these effects. Bibliographic databases were searched for the years 1963-2010 and resulted in 1652 articles. After elimination of duplicates or irrelevant papers, 204 papers were included and reviewed. Results indicated that OP and CB impair the enzymatic pathways involved in metabolism of carbohydrates, fats and protein within cytoplasm, mitochondria, and proxisomes. It is believed that OP and CB show this effect through inhibition of AChE or affecting target organs directly. OC mostly affect lipid metabolism in the adipose tissues and change glucose pathway in other cells. As a shared mechanism, all OP, CB and OC induce cellular oxidative stress via affecting mitochondrial function and therefore disrupt neuronal and hormonal status of the body. Establishing proper epidemiological studies to explore exact relationships between exposure levels to these pesticides and rate of resulted metabolic disorders in human will be helpful.

Prognostic value of long QT interval in acute and severe organophosphate poisoning

INTRODUCTION

Suicidal poisoning with organophosphorus (OP) pesticides is common, particularly from rural areas. This highlights the importance of determining an OP poisoning prognosis to decide how aggressive treatment should be. There are reports suggesting a relationship between prolonged corrected QT (QTC) interval and the severity of poisoning. We aimed to evaluate the prognostic utility of this clinical tool in OP poisoning (OPP) patients.

METHODS

Patients with the primary diagnosis of OPP who were admitted to the intensive care unit (ICU) of Loghman-Hakim Hospital Poison Centre (LHHPC) were the subjects of this prospective study. Cholinesterase (CE) activity and the QTC interval was determined for each patient using the Bazett formula and considering <440 msec as normal. Comparative outcomes of the study were duration of both hospitalization and mechanical ventilation, serum CE activity on admission and its daily level, total amount of atropine administered, analysis of the QT and QTC intervals in the primary ECG on admission and at the end of hospitalization, and rate of mortality.

RESULTS

The study included 42 patients with a diagnosis of OPP. The mean age of the patients was 32, ranged from 12 to 81 years old. The mortality rate was 37.5%. There was no significant difference between two groups (prolonged and normal QTC intervals) according to gender and age (p=.491 and p=.133, respectively). The CE level for long and normal QTC interval groups was 3.90+/-0.33 kU/L vs. 4.41+/-0.23 kU/L, respectively. The mortality rate in the long QTC group was significantly higher than that of the normal QTC group (p=.044). Moreover, the average period of hospitalization in patients with prolonged QTC interval was higher than the other group (p=.02). The average atropine required to control the muscarinic signs and symptoms such as salivation, bronchorrehea, and miosis in patients with prolonged QTC interval was 38.60 mg; in patients with normal QTC interval it was 20.02 mg (p=.013).

CONCLUSION

QTC interval prolongation may have prognostic value in OPP.

Reaction pathway and free-energy barrier for reactivation of dimethylphosphoryl-inhibited human acetylcholinesterase

The dephosphorylation/reactivation mechanism and the corresponding free-energy profile of the dimethylphosphoryl-inhibited conjugate of human acetylcholinesterase (AChE) has been studied by performing first-principles quantum mechanical/molecular mechanical free-energy (QM/MM-FE) calculations. On the basis of the QM/MM-FE results, for the favorable reaction pathway, the entire dephosphorylation/reactivation process consists of three reaction steps, including the nucleophilic water attack on the P atom, the spatial reorganization of the dimethylphosphoryl group, and the dissociation between the dimethylphosphoryl group and Ser203 of AChE. The overall free-energy barrier for the entire dephosphorylation/reactivation reaction is found to be the free-energy change from the initial reactant to the transition state associated with the spatial reorganization step, and the calculated overall free-energy barrier (20.1 to 23.5 kcal/mol) is reasonably close to the experimentally derived activation free energy of 22.3 kcal/mol. In addition, key amino acid residues and their specific roles in the reaction process have been identified.

Evaluation of the impacts of antibiotic drugs on PON 1; a major bioscavenger against cardiovascular diseases

Paraoxonase 1 (PON1) is an antiatherogenic enzyme which is also an organophosphate hydrolyzer. It has crucial roles in detoxification of highly toxic substances and protecting LDL against oxidation. Decrease in the levels of this enzyme is a great risk for the patients with cardiovascular diseases, diabetes mellitus, chronic renal failure, rheumatoid arthritis, hyperthyroidism, and age-related macular degeneration. Therefore, inhibitors and activators of PON1 must be well-characterized, and drug studies would be a good starting point in this regard. Moreover, purification of PON1 has been a challenge for scientists due to its tight association with HDL. Here we report the purification of human serum PON1 using very simple methods and investigation of the interactions between the enzyme and some commonly used antibiotics. We purified PON1 from human serum with a high specific activity, and used the pure enzyme for inhibition studies. We observed that some antibiotics inhibit the enzyme at very low doses while some are efficient at higher doses. The antibiotics exhibited different inhibition mechanisms. We concluded that usage of these antibiotics would be very dangerous in some cases.

Effects of Glycyrrhiza glabra polysaccharides on immune and antioxidant activities in high-fat mice

The purpose of this study was to investigate the immune and antioxidant activities of Glycyrrhiza glabra polysaccharides (GGP) in rats fed high-fat diet. The experiment was performed on four groups of growing Kunming mice. The results of the experiment showed a statistically significant decrease in serum antioxidant enzyme activities in high-fat group. Administration of GGP dose-dependently significantly enhanced immune and antioxidant enzyme activities in the GGP-treated mice compared to the high-fat model mice. It is concluded that GGP treatment can enhance immune activities, and reduce oxidative stress in high-fat mice.

Comparative Effects of Calcium Channel Blockers, Autonomic Nervous System Blockers, and Free Radical Scavengers On Diazinon-Induced Hyposecretion Of Insulin From Isolated Islets of Langerhans in Rats

Hyperglycaemia has been observed with exposure to organophosphate insecticides. This study was designed to compare the effects of calcium channel blockers, alpha-adrenergic, beta-adrenergic, and muscarinic receptor blockers, and of free radical scavengers on insulin secretion from diazinon-treated islets of Langerhans isolated from the pancreas of rats using standard collagenase digestion, separation by centrifugation, and hand-picking technique. The islets were then cultured in an incubator at 37 °C and 5 % CO2. In each experimental set 1 mL of 8 mmol L-1 glucose plus 125 μg mL-1 or 625 μg mL-1 of diazinon were added, except for the control group, which received 8 mmol L-1 glucose alone. The cultures were then treated with one of the following: 30 μmol L-1 atropine, 100 μmol L-1 ACh + 10 μmol L-1 neostigmine, 0.1 μmol L-1 propranolol, 2 μmol L-1 nifedipine, 50 μmol L-1 phenoxybenzamine, or 10 μmol L-1 alphatocopherol. In all experiments, diazinon significantly reduced glucose-stimulated insulin secretion at both doses, showing no dose dependency, as the average inhibition for the lower dose was 62.20 % and for the higher dose 64.38 %. Acetylcholine and alpha-tocopherol restored, whereas atropine potentiated diazinon-induced hyposecretion of insulin. Alpha-, beta- and calcium channel blockers did not change diazinon-induced effects. These findings suggest that diazinon affects insulin secretion mainly by disturbing the balance between free radicals and antioxidants in the islets of Langerhans and by inducing toxic stress.

Occupational exposure of farm workers to pesticides: biochemical parameters and evaluation of genotoxicity

To assess the effects of exposure to complex mixtures of pesticides in farm workers from two communities from Rio Grande do Sul, Brazil, we evaluated the activities of butyrylcholinesterase (BChE) and delta-aminolevulinic acid dehydratase (ALA-D) enzymes, hematological, lipid parameters, and genotoxicity using two tests to detect DNA damage, the Comet assay in peripheral blood leukocytes and the micronucleus (MN) test in oral mucosa cells. The use of personal protective equipment (PPE), age and smoke habits were considered in the analysis. There was a significant decrease in the BChE and ALA-D activities in farm workers (n=37) relative to the control group (n=20) (P< or =0.05 and P< or =0.001, respectively). The Comet assay in peripheral blood leukocytes showed that the Damage index and Damage frequency observed in the exposed group were significantly higher in relation to the controls (P< or =0.001, and P< or =0.05, respectively). No differences were detected regarding the hematological parameters, lipids profile, and MN frequencies. In addition, no significant differences were observed between younger (< or =38 years) and older subjects (>38 years), or between smokers and non-smokers within the groups, either by Comet assay or MN test. However, the use of PPE seems to be important in the prevention of contamination, as suggested by BChE levels and Comet assay results.

DNA damage after acute and chronic treatment with malathion in rats

Malathion is an insecticide widely used in agriculture and in public health programs that when used indiscriminately in large amounts can cause environmental pollution and risk to human health. However, it is possible that during the metabolism of malathion, reactive oxygen species can be generated, and malathion may produce oxidative stress in intoxicated rats that can be responsible for alterations in DNA molecules related in some studies. As a result, the present study aimed to investigate the DNA damage of cerebral tissue and peripheral blood in rats after acute and chronic malathion exposure. We used single cell gel electrophoresis (Comet assay) to measure early damage in hippocampus and peripheral blood and the Micronucleus test in total erythrocytes samples. Malathion was administered intraperitoneally once a day for one day (acute) or for 28 days (chronic) protocols (in both protocols, malathion was administered at 25, 50, 100, and 150 mg/kg). Our results showed that malathion (100 and 150 mg/kg) increased the DNA damage index in the peripheral blood and in the hippocampus after both chronic and acute treatment. Malathion increased the frequency of micronuclei only in chronic treatment at 150 mg/kg dose, and induced a cytotoxic dose-dependent decrease in the frequency of polychromatic erythrocytes in the peripheral blood of rats. In conclusion, since malathion increased both the peripheral blood and hippocampus DNA damage index using the Comet assay and increased the frequency of micronuclei in the total peripheral blood, it can be regarded as a potential mutagen/carcinogenic agent.

Fetal effects of environmental exposure of pregnant women to organophosphorus compounds in a rural farming community in Sri Lanka

BACKGROUND

The possible deleterious effects of low-grade, chronic environmental and occupational exposure to organophosphorus compounds (OPCs) are not well documented.

OBJECTIVE

To investigate the possible effects of low-level, chronic exposure of pregnant mothers to OPCs on the fetus by measuring OPC levels, and using markers of OPC exposure, oxidative stress and oxidative tissue damage.

METHODS

Toxicity was assessed by measuring (i) OPC levels in breast milk and plasma from maternal and cord blood using gas chromatography, (ii) maternal and fetal butyrylcholinesterase (BChE) activity using inhibition assays, (iii) antioxidant status of the fetus using superoxide dismutase activity assays, (iv) oxidative stress in the fetus by determining malondialdehyde (MDA) concentrations, and (v) examining for fetal DNA fragmentation using electrophoresis. Samples were obtained from consenting mothers living in a farming community in southern Sri Lanka at the end of the pesticide spray season (study group) and just before the commencement of the spray season (in-between spray season; control group).

RESULTS

Organophosphate residues were detected in only two subjects (chlorpyrifos in maternal and cord blood of one during the spray season and dimethoate in breast milk of another during the in between spray season), but the test employed was capable of only detecting concentrations above 0.05 mg/l. However, cord blood obtained during the spray season showed significant inhibition of BChE activity, increased oxidative stress and more DNA fragmentation when compared with cord blood obtained during the in-between spray season.

CONCLUSIONS

Inhibition of cord blood BChE activity indicates fetal exposure to organophosphorus compounds during times when there is a high probability of environmental drift. This provides a plausible explanation for the increased oxidative stress and high DNA fragmentation in the fetus. Long-term outcomes of such exposures are unknown.

Effects of azinphos-methyl exposure on enzymatic and non-enzymatic antioxidant defenses in Biomphalaria glabrata and Lumbriculus variegatus

Azinphos-methyl is an organophosphate insecticide used for pest control on a number of food crops in many parts of the world. The oligochaete Lumbriculus variegatus and pigmented and non-pigmented specimens of the gastropod Biomphalaria glabrata are freshwater invertebrates that have been recommended for contamination studies. Recently, it has been shown that L. variegatus worms exhibit a higher cholinesterase (ChE) activity and a greater sensitivity to in vivo ChE inhibition by azinphos-methyl than pigmented B. glabrata snails. The aims of the present study were (1) to investigate if, in addition to its anticholinesterase action, azinphos-methyl has also pro-oxidant activity in L. variegatus and B. glabrata, and (2) to examine if species that are highly susceptible to the neurotoxic effects of organophosphates also suffer a greater degree of oxidative stress. Therefore, total glutathione (t-GSH) levels and activities of cholinesterase (ChE), superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), and glucose 6-phosphate dehydrogenase (G6PDH) were measured in the whole body soft tissue of organisms exposed for 48 and 96 h to a level of azinphos-methyl that produces 50% of inhibition on ChE. Results showed different patterns of antioxidant responses between the gastropods and the oligochaetes, and even between the two phenotypes of gastropods: (1) in exposed L. variegatus t-GSH levels increased and CAT and SOD activities decreased with respect to control organisms, (2) in pigmented gastropods, SOD decreased while CAT transiently diminished, and (3) in non-pigmented gastropods, SOD activity showed a biphasic response. GST and G6PDH were not altered by azinphos-methyl exposure. Of note, t-GSH levels were 4-fold times higher in L. variegatus than in both phenotypes of B. glabrata. This may suggest that GSH could play a more important role in antioxidant defense in L. variegatus than in B. glabrata.

Effect of oral administration of fenitrothion on biochemical and hematological parameters in rats

The aim of this study was to evaluate the effects of acute exposure to various doses of fenitrothion (FNT) on level of serum glucose, total protein, triglycerides (TG), total cholesterol (TC) and some hematological parameters. The study was conducted on 8-week-old male Wistar rats that divided into four groups (three experimental groups and one control group), were treated orally with different doses (25, 50 and 100 mg kg(-1)) of fenitrothion for 28 consecutive day. After treatment, blood samples were collected for biochemical and hematological studies. Present results demonstrated that exposed groups led to significant dose-dependent increase in serum glucose and cholesterol levels. Significant decrease was observed in some hematological parameters [Red Blood Cell (RBC) counts, Hemoglobin (Hb), Haematocrite (Ht) and Mean Corpuscular Hemoglobin (MCH) values]. Serum total protein and triglycerides were also decreased not significantly in exposed groups when compared with control. Generally, the degrees of observed variations were found to be dose dependent.

Comet assay: a reliable tool for the assessment of DNA damage in different models

New chemicals are being added each year to the existing burden of toxic substances in the environment. This has led to increased pollution of ecosystems as well as deterioration of the air, water, and soil quality. Excessive agricultural and industrial activities adversely affect biodiversity, threatening the survival of species in a particular habitat as well as posing disease risks to humans. Some of the chemicals, e.g., pesticides and heavy metals, may be genotoxic to the sentinel species and/or to non-target species, causing deleterious effects in somatic or germ cells. Test systems which help in hazard prediction and risk assessment are important to assess the genotoxic potential of chemicals before their release into the environment or commercial use as well as DNA damage in flora and fauna affected by contaminated/polluted habitats. The Comet assay has been widely accepted as a simple, sensitive, and rapid tool for assessing DNA damage and repair in individual eukaryotic as well as some prokaryotic cells, and has increasingly found application in diverse fields ranging from genetic toxicology to human epidemiology. This review is an attempt to comprehensively encase the use of Comet assay in different models from bacteria to man, employing diverse cell types to assess the DNA-damaging potential of chemicals and/or environmental conditions. Sentinel species are the first to be affected by adverse changes in their environment. Determination of DNA damage using the Comet assay in these indicator organisms would thus provide information about the genotoxic potential of their habitat at an early stage. This would allow for intervention strategies to be implemented for prevention or reduction of deleterious health effects in the sentinel species as well as in humans.

A biochemical study on variability of Superoxide dismutase, Catalase and Glutathione peroxidase in dry cleaners

Several chemicals which induce cytotoxicity are broadly classified into three types and they are organophosphate, organochlorine and carbomate compounds. Perchloroethylene has been clearly identified as a carcinogen in experimental animals and it's a very common carcinogen used for dry clean purpose. Hence, in the present study, blood samples from dry cleaners were taken, Superoxide dismutase, Catalase and Glutathione peroxidase activity was estimated in blood samples of dry cleaners. There was a significant increase in the activity of Catalase, Glutathione Peroxidase, Superoxide Dismutase in dry cleaners of chronically exposed to perchloroethylene as compared to controls. The increased activities of antioxidant enzymes may be a compensatory regulation in response to increased oxidative stress induced by perchloroethylene.

Biomonitoring of organochlorines, glutathione, lipid peroxidation and cholinesterase activity among pesticide sprayers in mango orchards

BACKGROUND

Pesticide sprayers in mango orchards of Malihabad, Lucknow (India) are generally exposed to organophosphate (OP) and pyrethroid pesticides. We determined the pesticide exposure levels along with their biochemical and clinical effects in 31 sprayers, compared with 18 controls.

METHODS

Assay of acetyl and butyrylcholinesterases (AChE, BChE respectively) as an indirect measurement of OP exposure and levels of malondialdehyde (MDA) and glutathione (GSH) were estimated in blood samples to determine their impact on redox potential. Organochlorines were estimated by GLC-ECD.

RESULTS

Significantly inhibited AChE, BChE activities and higher MDA level were found among sprayers compared to controls (p<0.05). Mean of total organochlorines were surprisingly higher (97.65+/-13.38 ppb) in sprayers than in those of controls (20.42+/-3.56 ppb) (p<0.05). Respiratory morbidity (32.4%), ocular problems (8.8%), gastrointestinal (17.6%) and skin problems (23.5%) were found in sprayers. There was significant correlation between AChE and GSH (r=0.29, p<0.05) and AChE with MDA (r=-0.34, p<0.05).

CONCLUSION

Results indicated the significantly enhanced lipid peroxidation in sprayers correlated with cholinesterases inhibition. A small sample size limits the significance of this study. However, it paves the way for a larger Indian study with extended practical significance.

Antioxidant Activity of Iranian Echium amoenum Fisch & C.A. Mey Flower Decoction in Humans: A cross-sectional Before/After Clinical Trial

Medicinal plants are recognized as sources of natural antioxidants that can protect from biological system oxidative stress. The present cross-sectional before/after clinical trial was carried out to investigate the antioxidant properties of the decoction of the flowers of Echium amoenum Fisch & C.A. Mey in humans. A group of 38 healthy subjects was invited to use the E. amoenum (7 mg kg(-1)) twice daily for 14 days. Blood samples before and after entering the study were measured for lipid peroxidation level (LPO), total antioxidant capacity (TAC) and total thiol (SH) molecules. A significant reduction of blood LPO (24.65 +/- 11.3 versus 19.05 +/- 9.7, P = 0.029) was observed after 14 days of E. amoenum consumption. Blood TAC (1.46 +/- 0.51 versus 1.70 +/- 0.36, P = 0.018) and total thiol molecules (0.49 +/- 0.11 versus 0.56 +/- 0.12, P = 0.001) increased after 14 days of E. amoenum consumption. In conclusion, this antioxidative stress potential of E. amoenum may be due to its bioactive antioxidant components, especially rosmarinic acid and flavonoids. In recent years the importance of oxidative stress in the pathophysiology of many human disorders has been confirmed, thus use of this plant as a dietary supplement is highly recommended.

Possible mechanism of pesticide toxicity-related oxidative stress leading to airway narrowing

The study was conducted to assess the magnitude of oxidative stress and lung function abnormalities in 34 male pesticide sprayers on exposure to pesticides in mango plantations. Biochemical studies on blood antioxidant enzymes revealed an unchanged glutathione level and increased level of malondialdehyde (P < 0.001), which indicates that pesticide sprayers may have suffered from oxidative stress. Decreased acetyl-cholinesterase levels (P < 0.001) in sprayers compared to the controls suggest inhibition of cholinesterase activity. The present study shows that pesticide toxicity might lead to oxidative stress and airway narrowing resulting in decreased peak expiratory flow rate.

Genotoxic evaluation of workers employed in pesticide production

Pesticides are widely used throughout the world in agriculture to protect crops and in public health to control diseases. Nevertheless exposure to pesticides can represent a potential risk to humans. Pesticide manufacturing unit workers are prone to possible occupational pesticide exposure. Therefore, this study was performed to evaluate the genotoxic effect of pesticide exposure in these workers. In the present investigation 54 pesticide workers and an equal number of control subjects were assessed for genome damage in blood lymphocytes utilizing the chromosomal aberration analysis and the buccal epithelial cell by adopting the micronucleus test. The results suggested that pesticide workers had a significantly increased frequency of chromosomal aberrations when compared with controls (mean+/-S.D., 8.43+/-2.36 versus 3.32+/-1.26; P<0.05). Similarly, the pesticides exposed workers showed a significant increase in micronucleated cells compared with controls (1.24+/-0.72 versus 0.32+/-0.26; P<0.05). Analysis of variance revealed that occupational exposure to pesticides had a significant effect on frequency of micronuclei (P<0.05), whereas smoking, age, gender and alcohol consumption had no significant effect on genetic damage (P>0.05). However, no association was found between years of exposure, smoking, age, gender, alcohol consumption and higher levels of genetic damage as assessed by the chromosomal aberration assay (P>0.05). Our findings indicate that occupational exposure to pesticides could cause genome damage in somatic cells.