Hepatoprotective role of captopril on paraquat induced hepatotoxicity

Paraquat (PQ) is a highly toxic herbicide that is used in most of the countries without restriction. The cytotoxic effect of PQ is mediated by radicals, which are the products of PQ reduction in cells. The anti-oxidative action of captopril, an angiotensin-converting enzyme inhibitor, appears to be through its ability to scavenge reactive oxygen species. In this study, the heptoprotective effect of captopril against PQ-induced hepatotoxicity was evaluated using primary cultured rat hepatocytes. Hepatocytes were isolated from male Wistar rats using a two-step collagenase perfusion, following incubation in the presence of captopril at 0.1, 0.2, 0.4 and 0.8 mM with or without PQ (5 mM). Hepatoprotective effects of captopril were studied indicating glutathione level intensity, thiobarbituric acid reactive substances (TBARs) formation, lactate dehydrogenase (LDH) leakage and cell viability every 70 min for 210 min. Captopril at 0.2 mM concentration maintained the LDH leakage, glutathione level and cell viability in the presence of 5 mM PQ. In spite of a significant elevation in TBARs formation in the PQ group, captopril did not show any significant protection. In conclusion, our data reveals that incubation of freshly isolated rat hepa-tocytes with captopril (0.2 mM) significantly protected the hepatocytes against the cytotoxicity of PQ ( P < 0.05). Human & Experimental Toxicology (2007) 26, 789— 794

Deferoxamine preconditioning to restore impaired HIF-1α-mediated angiogenic mechanisms in adipose-derived stem cells from STZ-induced type 1 diabetic rats

OBJECTIVES

Both excessive and insufficient angiogenesis are associated with progression of diabetic complications, of which poor angiogenesis is an important feature. Currently, adipose-derived stem cells (ADSCs) are considered to be a promising source to aid therapeutic neovascularization. However, functionality of these cells is impaired by diabetes which can result from a defect in hypoxia-inducible factor-1 (HIF-1), a key mediator involved in neovascularization. In the current study, we sought to explore effectiveness of pharmacological priming with deferoxamine (DFO) as a hypoxia mimetic agent, to restore the compromised angiogenic pathway, with the aid of ADSCs derived from streptozotocin (STZ)-induced type 1 diabetic rats ('diabetic ADSCs').

MATERIALS AND METHODS

Diabetic ADSCs were treated with DFO and compared to normal and non-treated diabetic ADSCs for expression of HIF-1α, VEGF, FGF-2 and SDF-1, at mRNA and protein levels, using qRT-PCR, western blotting and ELISA assay. Activity of matrix metalloproteinases -2 and -9 were measured using a gelatin zymography assay. Angiogenic potential of conditioned media derived from normal, DFO-treated and non-treated diabetic ADSCs were determined by in vitro (in HUVECs) and in vivo experiments including scratch assay, three-dimensional tube formation testing and surgical wound healing models.

RESULTS

DFO remarkably enhanced expression of noted genes by mRNA and protein levels and restored activity of matrix metalloproteinases -2 and -9. Compromised angiogenic potential of conditioned medium derived from diabetic ADSCs was restored by DFO both in vitro and in vivo experiments.

CONCLUSION

DFO preconditioning restored neovascularization potential of ADSCs derived from diabetic rats by affecting the HIF-1α pathway.

Acute inhalation exposure to titanium ethanolate as a possible cause of metal fume fever

Occupational inhalation exposure to noxious agents is not uncommon. Herein, we present a 26-year-old male student who had accidental acute inhalation exposure to a large quantity of titanium ethanolate and hydrogen chloride in chemistry lab. He was referred to the emergency department of our hospital with low-grade fever, dyspnea, headache, fatigue and myalgia. After 24 hrs of symptomatic treatment (oxygen therapy and acetaminophen), the fever was subsided and the patient discharged home in a good clinical condition. The presented symptoms could be interpreted as a form of metal fume fever. It can therefore be concluded that organo-metallic compound of titanium metal may have the potential to produce metal fume fever in human.

Intestinal obstruction in acute inhalational toluene 2,4-diisocyanate gas toxicity

The isocyanates are widely used as precursors of polyurethane products, as well as carbamate insecticides. Toluene 2,4-diisocyanate (TDI) is one of the most important commercially used isocyanates. Humans may be exposed to TDI by inhalation, ingestion, dermal and eye contact. TDI is a powerful irritant to the mucosal membranes of the gastrointestinal and respiratory tracts, eyes and the skin. Pulmonary manifestations, especially occupational asthma, are the predominant manifestations after TDI toxicity. Herein, we present intestinal obstruction as an extraordinary manifestation of acute TDI toxicity after occupational exposure. TDI toxicity may cause intestinal obstruction.

Enzymuria determination in children treated with aminoglycosides drugs

Although aminoglycosides antibiotics are used in children and adult commonly, they have serious side effects such as nephrotoxicity and ototoxicity. In clinical practice, for renal function, the levels of serum creatinine and blood urea nitrogen routinely are measured. Since these parameters have limitations such as unreliability, insensitivity, and nonspecificity, the rapid assessment of renal function based on these patients is very important. Increase in N-acetyl-β-D-glucosaminidase (NAG), a hydrolytic lysosomal enzyme, suggests proximal tubular cell damage. In this study, 32 children aged 2 months through 2 years, treated with gentamicin and amikacin for suspected infections at the pediatric ward of Alborz hospital from September 2006 to February 2007, were enrolled. Serum and fresh urine before and after drug infusion were obtained on the 1st, 3rd, and 5th days of antibiotic treatment. Serum urea and creatinine with urinary creatinine, albumin, NAG, lactate dehydrogenase (LDH) and alkaline phosphatase (AP) activity were then determined. A statistically significant increase in urinary NAG, LDH, and AP on 5th day was found compared with before gentamicin administration ( P < 0.001, P < 0.01, P < 0.05, respectively). The urinary NAG activity may be a useful indicator of renal injury in children treated with aminoglycosides drugs compared with other routine clinical indicators.

Alternative electron acceptors: Proposed mechanism of paraquat mitochondrial toxicity

Paraquat (PQ) is a relatively safe and effective herbicide used all over the world. PQ is very toxic to all living organisms; and many cases of acute poisoning and death have been reported over the past decade. The main suggested potential mechanism for PQ toxicity is the production of superoxide radicals from the metabolism of the PQ by microsomal enzyme systems, and by inducing mitochondrial toxicity. Mitochondria are considered to be a major source of reactive oxygen species in cells and according to this hypothesis, PQ, through suitable oxidation and reduction processes, is able to participate in the redox system in mitochondria. The potential ability of PQ to accept electrons from complex (I, II, III, IV) leads to rapid reaction with molecular oxygen to yield superoxide anion which can lead to the formation of more toxic reactive oxygen species, e.g., hydroxyl radical, often taken as the main toxicant. Lipid peroxidation due to PQ has been implicated in a number of deleterious effects such as increased membrane rigidity, osmotic fragility, decreased mitochondrial components, reduced mitochondrial survival and lipid fluidity. The biological effect of reactive oxygen species (ROS) is controlled by a wide spectrum of enzymatic and non-enzymatic defense mechanisms such as superoxide dismutas (SOD), catalase (CAT) and glutathione. According to this hypothesis, the chemical cascades lead to the reduction of PQ, which reacts quite rapidly with molecular oxygen to yield superoxide anion. The generation of free radicals and lipid peroxidation are the main factors that lead to mitochondrial damage.

Using Janus green B to study paraquat toxicity in rat liver mitochondria: role of ACE inhibitors (thiol and nonthiol ACEi)

Janus green B (JG-B) dye is used for vital staining of mitochondria and its reduction and oxidation shows the electron transfer chain alteration. The defect in electron transfer chain of mitochondria by paraquat is linked to free radical formation. In this present study we compared the abilities of different angiotensin-converting enzyme inhibitors, captopril (a thiol ACEi), enalapril, and lisinopril (two nonthiol ACEi) on mitochondria toxicity due to paraquat. The rat liver mitochondria were first isolated by centrifuge (at 4 degrees C at a speed of 7,000 g) in a mixture of 0.25 M saccharose solution and 0.05 M Tris buffer. Various concentrations of paraquat (1, 5, 10 mM), enalapril (0.25, 0.5, 1 mM), lisinopril (0.01, 0.05, 0.1 mM), and captopril (0.08, 0.1, 1 mM) on the mitochondria isolated from the liver with respect to time were investigated. Paraquat at a concentration of 5 mM was determined to be significantly different compared to control values (P<0.05) and captopril at a concentration of 0.08 mM, lisinopril (0.01 mM), and enalapril (0.25 mM) were found not to be significantly different from controls as found by spectroscopy at wavelength of 607 nm. Simultaneous treatment of mitochondria with captopril (0.08 mM) and paraquat (5 mM) significantly ameliorates the mitochondria toxicity of paraquat (5 mM) alone (P<0.05). Our results show that captopril is a more effective antioxidant than the nonthiol ACEi. Lisinopril (0.01 mM) and enalapril (0.25 mM) did not significantly change the mitochondrial toxicity by paraquat (5 mM) (P>0.05). The antioxidative action of captopril appears to be attributable to the sulfahydryl group (SH) in the compound. This effect may be due to captopril's abilities to scavenge reactive oxygen species.

Captopril ameliorates toxicity induced by paraquat in mitochondria isolated from the rat liver

The aim of the present study was to show the abilities of captopril as a thiol ACEi (angiotensin converting enzyme inhibitor), on mitochondria toxicity due to paraquat. Mitochondrial isolation from rat liver was divided into 4 groups. Group 1 was considered as control, group 2 received paraquat (5 mM), group 3 received captopril (0.08 mM) and group 4 received paraquat (5 mM)+captopril (0.08 mM). Lipid peroxidation, catalase activity, GSH (reduced glutathione) and GSSG (oxidized glutathione) concentrations were determined in isolated rat liver mitochondria. Simultaneous treatment of mitochondria with captopril (0.08 mM)+paraquat (5 mM) significantly ameliorate the mitochondria toxicity induced by paraquat (5 mM) alone. The results confirm antioxidant effect of captopril. This effect appears to be attributable to the Sulfhydryl Groups (SH) in the compound which may be due to captopril abilities to scavenge reactive oxygen species. The results indicate that captopril may prevent oxidative stress induced by paraquat.

Protective effect of melatonin against multistress condition induced lipid peroxidation via measurement of gastric mucosal lesion and plasma malondialdehyde levels in rats

AIM

To study the protective effect of a natural antioxidant, melatonin, against multistress condition induced lipid peroxidation via determination of gastric damage and plasma malondialdehyde (MDA) level by high performance liquid chromatography in rats.

METHODS

We compared indomethacin-induced gastric damage and MDA plasma level in three groups of rats: unoperated, bile duct ligated and sham-operated and evaluated the role of the melatonin on gastric damage and plasma MDA level. Indomethacin and melatonin were injected intraperitoneally in doses of 50 mg/kg and 20 mg/kg, respectively. Animals were killed 4 h after indomethacin injection.

RESULTS

Indomethacin induced more severe gastric damage and plasma MDA level in bile duct ligated animals was significantly higher (3.1 +/- 0.04 micromol/L) than sham (2.8 +/- 0.04 micromol/L) and unoperated animals (1.4 +/- 0.08 micromol/L). Pretreatment with melatonin reduced indomethacin-induced gastric damage and plasma MDA level.

CONCLUSION

Considering the results of this study, we suggest that in multistress conditions the intensity of gastric damage and the plasma MDA level are great and melatonin reduces the negative effect of lipid peroxidation and cell damage by oxidative stress in multistress conditions due to its antioxidizing activity.

Heavy metals (Ni, Cr, Cu) in the Karoon waterway river, Iran

Environmental pollution is a world-wide problem, heavy metals belonging to the most important pollutants. The progress of industries has led to increased emission of pollutants into ecosystems. Karoon is the biggest and only navigable river in the South of Iran. Along the Karoon industrial units such as piping, steel, paint making, agriculture, paper mill, fish cultivation, abbottiors, electroplating industries drain their wastewater into the river. In this study, the concentrations of heavy metals (Ni, Cr, Cu) in the Karoon river have been determined. Samples were collected from 16 stations along the river, in winter and spring 1996. Heavy metal concentrations were measured by graphite furnace atomic absorption spectrometry. The minimal and maximal concentrations of these metals in winter were 69.3-110.7, 1.7-118.3, and 5.5-70.3 microg/l, for Ni, Cr, and Cu, respectively. The minimal and maximal concentrations of these metals in spring were 41.0-60.7, 0.7-19.8, and 0.5-28.7 microg/l, for Ni, Cr, and Cu, respectively. The results show that the pollution has increased along the river, down to the estuary at the Persian Gulf.

The bacterial endotoxin lipopolysaccharide enhances seizure susceptibility in mice: involvement of proinflammatory factors: nitric oxide and prostaglandins

Central nervous system (CNS) inflammation in cases such as head trauma, infection and stroke has been associated with the occurrence of epileptic seizures. Microglia, the principal immune cells in the brain, readily become activated in response to injury, infection or inflammation. The bacterial endotoxin lipopolysaccharide (LPS) induces the activation of microglia and the production of proinflammatory factors including nitric oxide (NO) and prostaglandins (PGs). We examined the effect of LPS on seizure susceptibility of mice, by using the sensitive test, threshold of clonic seizures induced by i.v. infusion of pentylenetetrazole. LPS decreased the seizure threshold in a dose- and time-dependent manner. Pretreatment of mice with the NO synthase inhibitor, N(G)-nitro-L-arginine methyl ester or cyclooxygenase inhibitor, piroxicam or the opioid receptor antagonist, (-)-naloxone completely reversed the proconvulsant effect of LPS. These results indicate that NO, PGs and endogenous opioid peptides seem to be involved in LPS-induced decrease in seizure threshold.

Survey of the natural occurrence of zearalenone in maize from northern Iran by thin-layer chromatography densitometry

During September 2000, forty samples of preharvest maize from the province of Mazandaran, north Iran, were randomly collected. Samples were analysed for zearalenone (ZEA) by a thin-layer chromatography (TLC) method (AOAC Official Method). ZEA was extracted with chloroform, purified through a chromatographic column containing silica gel, separated on a TLC plate and quantified by densitometry. The analytical method was validated and was adequately reliable and sensitive. The mean recovery rate of ZEA from spiked samples was 92%. The absolute amount of ZEA standard detectable on a TLC plate was 20 ng, giving a limit of detection (LOD) of 100 ng g(-1). In some samples, it was shown that aflatoxins interfere with ZEA. Therefore, to remove this interference, the TLC mobile phase was changed. Data revealed that three of 40 (7.5%) maize samples contained ZEA in the range 100-212 ng g(-1), with a mean of 141+/-51 ng g(-1). This study, which is the first report of ZEA occurrence in Iranian maize, showed that the ZEA level in maize of Mazandaran province was lower than maximum limit for this mycotoxin in Iran.

In vitro inhibitory effects of antioxidants on cytotoxicity of T-2 toxin

T-2 toxin is a secondary fungal metabolite produced by various species of Fusarium. It is capable of killing cells by causing extensive damage to the cellular membrane. In this study, cytotoxicity of T-2 toxin in combination with different antioxidant materials, including vitamin C (vit. C), vitamin E (vit. E) and selenium (sel) was investigated in vitro using the neutral red cytotoxicity assay. Eleven primary and transformed cell lines established from different tissues were used in pre-test experiments to identify the most sensitive and resistant lines by measuring the half lethal concentration (LC(50)) of the toxin. Three cell lines including human gingival fibroblast (HGF), the most sensitive (LC(50)=0.25 ng/ml), human colorectal adenocarcinoma (SW742), the most resistant (LC(50)=5.5 ng/ml) and human hepatoma (HepG2), with median susceptibility (LC(50)=2 ng/ml) were selected to investigate the inhibitory effects of the antioxidant agents, on cytotoxicity of T-2 toxin. Our results demonstrated that co-incubation of cell lines with different concentrations of T-2 toxin and antioxidants decreased significantly, but did not totally inhibit, the cytotoxicity of T-2 toxin (P<0.001). These findings suggest that in addition to lipid peroxidation, which is inhibited by antioxidants, other unidentified mechanism(s) seem to be involved in cytotoxicity of T-2 toxin.

Increase by NO synthase inhibitor of lead-induced release of N-acetyl-beta-D-glucosaminidase from perfused rat kidney

Urinary N-acetyl-beta-D-glucosaminidase (NAG) had been shown to be a useful early marker of renal injury such as lead nephrotoxicity. This study investigated the effect of lead acetate on nephrotoxicity and its correlation with the nitric oxide (NO) system by determining the NAG release in perfused rat kidney. Lead acetate caused a time and concentration-dependent increase in enzymuria. The effect of concurrent perfusion with lead and L-arginine (L-arg) or L-N(G)-nitro arginine methyl ester (L-NAME) [substrate and inhibitor of NO synthase respectively] in the perfusion fluid was also studied by measuring NAG activity in the perfusate kidney rat. L-arg (2 mM) has significantly decreased the lead-induced NAG release (P < 0.001), and L-NAME (0.1 mM) has significantly increased the lead-induced enzyme release in a time-dependent manner (P < 0.001). Moreover, histological studies using light microscope showed that some of the epithelial cells of the proximal convoluted tubules are degenerated or necrotic and desquamated into the lumens in rat treated with lead acetate. This change occurs at 50 microg/dl of lead acetate and was increased by addition of L-NAME to lead acetate. However, addition of L-arg had no effect on histology of lead nephrotoxicity. This may suggest that lead may interfere with the NO system in rat kidney.

Effects of lead exposure on licking and yawning behaviour in rats

In the present study, effects of lead exposure on licking and yawning behaviour have been studied. The dopaminergic receptor agonist, apomorphine (0.15, 0.25 and 0.5 mg/kg), induced dose-dependent licking in rats. The maximum response was obtained with 0.5 mg/kg of the apomorphine. Lead acetate (0.05%) exposure significantly increased apomorphine-induced licking. Yawning induced by the D2 dopaminergic agonist, bromocriptine (2, 3, 4, 8 mg/kg), and the cholinergic drug, physostigmine (0.1 or 0.3 mg/kg), was significantly decreased by lead acetate (0.05%) exposure. It may be concluded that the behaviour induced by dopaminergic or cholinergic agents can be affected by lead subchronic exposure.

Effects of caerulein and CCK antagonists on tolerance induced to morphine antinociception in mice

Different groups of mice received one daily dose (50 mg/kg) of morphine subcutaneously (SC) for 3, 4 or 5 days to develop tolerance to the opioid. The antinociceptive response of morphine (9 mg/kg) was tested in the hot-plate test 24 h after the last dose of the drug. Tolerance to morphine was obtained in all groups. The group of mice that received morphine for 4 days was employed for the rest of the experiments. Pretreatment of animals with a single dose of caerulein (0.025, 0.05, and 0.1 mg/kg, SC) 30 min prior to receiving morphine (50 mg/kg; during the development of tolerance to the opioid) on day 1, 2, 3, 4 or 5 of morphine administration potentiate antinociception induced by morphine (test dose of 9 mg/kg). The dose of 0.05 mg/kg of caerulein, used 30 min before morphine administration on day 3, was also used to evaluate the effects of antagonists on caerulein-induced decrease in tolerance. The selective cholecystokinin (CCK) receptor antagonists, MK-329 [1-methyl-3-(2 indoloyl)amino-5-phenyl-3H-1,4-benzodiazepin-2-one; 0.25 and 0.5 mg/kg] or L-365,260 [3R(+)-N-(2,3-dihydro-1-methyl-2-oxo-5-phenyl-1H- 1,4-benzodiazepin-3-yl)-N-(3-methyl-phenyl)urea: 0.25 and 0.5 mg/kg] decreased potentiation of morphine response induced by caerulein. MK-329 or L-365,260, when were injected 35 min before morphine injection during the development of tolerance and on day 3, decreased the tolerance to morphine. A single administration of MK-329 or L-365,260 (in the absence of caerulein) 35 min and 48 h before the test dose of morphine (9 mg/kg) potentiated the antinociception of morphine in nontolerant animals. In conclusion, CCK mechanism(s) may interact with morphine tolerance.

Effects of lead exposure on bromocriptine-induced penile erection in rats

In the present work we have studied the effects of lead exposure on penile erection induced by bromocriptine. Intraperitoneal injection of bromocriptine (2, 3, 4 and 8 mg/kg) induced dose-related penile erection in rats. Maximum response was observed with 4 mg/kg of the drug. Lead exposure (as Pb-acetate in drinking water) for periods of 7, 14, 21 and 28 days decreased the bromocriptine-induced penile erection response. Higher concentrations of lead (0.05%) were shown to cause a more prominent decrease of penile erection. The same procedure for lead administration did not significantly alter penile erection induced by physostigmine (0.1 and 0.3 mg/kg, intraperitoneally). In a series of experiments, blood lead concentrations were measured 7 and 21 days after lead exposure. Significant increases of lead concentrations were found after lead exposure. It is concluded that lead can influence bromocriptine-induced penile erection.

Effects of cholecystokinin receptor agonist and antagonists on morphine dependence in mice

In the present study, the effect of cholecystokinin agonists and antagonists on dependence to morphine in mice has been investigated. Mice were treated subcutaneously with morphine (50, 50 and 75 mg/kg) three times daily for 2-4 days, and a last dose of morphine (50 mg/kg) was administered on day 3, 4 or 5. Withdrawal syndrome (jumping) was precipitated by naloxone (2.5, 5 and 10 mg/kg) which was administered intraperitoneally 2 hr after the last dose of morphine. To study the effects of cholecystokinin receptor agonists or antagonists, 10 injection of morphine (3 administrations each day) for dependence and a dose of 5 mg/kg of naloxone for withdrawal induction were employed. Cholecystokinin-8 (0.001-0.01 mg/kg), low doses of the cholecystokinin agonists caerulein (0.00001 and 0.0001 mg/kg) and, unsulfated cholecystokinin (but not high doses) as well as the antagonists MK-329 (0.5-1 mg/kg) and L-365,260 (0.5-1 mg/kg) elicit reduction of the nalaxone-induced jumping. The inhibition of jumping induced by caerulein was reduced with the selective cholecystokinin antagonists MK-329 and L-365,260. It is concluded that cholecystokinin mechanism(s) may be involved in morphine dependence, that the agonists may act on a presynaptic receptors and that the antagonists may work on postsynaptic receptors.

A prospective study of fatal outcomes of poisoning in Tehran

Data on 194 fatal poisoning cases admitted to various hospitals in Tehran over a 1-y period showed an overall male:female ratio of 1.9:1, with females predominating only in the 13-19 y age group. Fifty-five percent of the deaths were attributed to suicide, affecting more females than males. Most cases were referred to hospitals between 1 pm and 1 am. There was a slight seasonal variation, with the highest number of cases in July and March and the lowest in April. Drugs were the most frequently used poison (27%) followed closely by pesticides (24%). Benzodiazepines and tricyclic antidepressants accounted for 38% of drug-related poisonings, with diazepam (61%), imipramine (44%) and amitriptyline (33%) the most commonly used agents in each group. Insecticides were responsible for 58% of pesticide-related deaths. Following pesticides, 13% of the deaths were due to chemicals, with depilator and solvent abuse accounting for 88% of the cases in this group.

Effects of 5-HT receptor antagonists on morphine-induced tolerance in mice

The effect of 5-HT receptor antagonists on tolerance to morphine antinociception was studied in mice. Slow release morphine suspension was injected subcutaneously (s.c.) in order to produce tolerance. When different doses of morphine (3, 6 and 9 mg/kg) were administered on the 4th day after injection of slow-release morphine suspension, tolerance to the test doses of morphine was observed. The tolerance obtained was decreased by pretreatment with the non-selective 5-HT receptor antagonist methysergide (1 and 2 mg/kg) or the 5-HT2 receptor antagonist ritanserin (1 and 2 mg/kg). When the 5-HT receptor antagonists were used on the 2nd and 3rd day after injection of slow-release morphine suspension or on the 4th day (60 min before last dose of morphine), a maximum reduction in morphine tolerance was observed on the 3rd day. Pretreatment of animals with metergoline (1 and 2 mg/kg) or mianserin (1 and 2 mg/kg) also decreased the tolerance to morphine. It may be concluded that at least a 5-HT2 receptor mechanism is involved in tolerance to morphine antinociception.