Meconium aspiration induces oxidative injury in the hippocampus of newborn piglets

Background

Meconium aspiration-induced hypertensive lung injury has been associated with neuronal damage in the newborn, but the mechanisms of the injury are poorly known.

Aims

The aim of the study was to determine the contribution of oxidative stress to the brain damage after pulmonary meconium contamination.

Study design

Sixteen anesthetized and ventilated newborn piglets were studied for 6 h. Eight piglets were instilled with a bolus of human meconium intratracheally and eight piglets with saline instillation served as controls. Brain tissue lipid peroxidation products (TBARS), reduced glutathione (GSH), myeloperoxidase activity and oxidized DNA were analyzed as indicators of oxidative stress.

Results

Meconium aspiration did not change the systemic or carotid hemodynamics, but caused a well-established pulmonary hypertensive response. Sustained increase in additional oxygen demand was also observed after meconium insult, but no actual hypoxemia or hypercarbia was evident during the whole study period. Myeloperoxidase activity was elevated in the cerebellum after pulmonary meconium instillation, whereas concentrations of peroxidation products and glutathione were similar in the cortical, cerebellar and hippocampal regions of the two groups. Still, the amount of oxidized DNA was increased in the hippocampus of the meconium-aspirated piglets when compared to controls.

Conclusions

Our data thus suggest that oxidative injury associated with pulmonary, but not systemic, hemodynamic disturbances may contribute to hippocampal damage after meconium aspiration in newborns.     

A two-year dietary carcinogenicity study of cyadox in Sprague-Dawley rats

To investigate the potential carcinogenicity of cyadox, an antimicrobial agent, four groups of Sprague-Dawley rats (50 rats/sex/group) were fed diets containing cyadox (0, 200, 600 or 2000 mg/kg) for up to two years. There were significant decreases in body weight, feed intake and feed efficiency in both genders during most of the period in the 2000 mg/kg group. Significant decreases in serum ALT were observed in the 2000 mg/kg group at weeks 52, 78 and 104. For the control, 200, 600, and 2000 mg/kg groups, the tumor incidence in females was 33.3%, 37.2%, 40.0% and 19.0%, while it in males it was 18.9%, 2.6%, 17.1% and 13.6%, respectively. At histopathology, no increases in tumor incidence were attributed to treatment with cyadox. The mild swelling and fatty degeneration in hepatocytes, and mild swelling and tubular necrosis in the kidney were observed in 2000 mg/kg group. The no-observed-effect-level (NOEL) for carcinogenicity of cyadox fed to rats was 2000 mg/kg diet (132.18–156.28 mg/kg b.w./day). In conclusion, cyadox was not carcinogenic to rats with the liver and kidney as the target organs, and the side chain may be involved in toxicity and carcinogenicity mediated by QdNOs.     

A novel chitosan based antimalarial drug delivery against Plasmodium berghei infection

Chitosan is a natural polysaccharide that has attracted significant scientific interest during the last two decades and chitosan based nanodrug delivery systems seem to be a hopeful and viable strategy for improving disease treatment. This study aims to evaluate the potency of the polymer based nanochloroquine in application for attenuation of Plasmodium berghei infection in Swiss mice and effectiveness against the parasite induced oxidative stress and deoxyribo nucleic acid (DNA) damage in lymphocytes. Nanoparticle was prepared by ionotropic gelation between chitosan and sodium tripolyphosphate. The chloroquine was treated by the actual drug content of effective nanochloroquine and the nanodrug was charged with its effective dose for fifteen days, after successive infection development in Swiss mice. Gimsa staining of thin smear and flow cytometry analysis was pursued to reveal the parasitemia. Different oxidative markers, inflammatory markers, antioxidant enzymes level and also lymphocytic deoxyribo nucleic acid damage study were performed. The present study reveals the potency of the nanodrug which has been found as more prospective than only chloroquine treatment to combat the parasite infection, oxidative stress as well as inflammation and DNA damage. From the study, we conclude this nanodrug may be applicable as potent therapeutic agent than only chloroquine.     

Hepatoprotective properties of kombucha tea against TBHP-induced oxidative stress via suppression of mitochondria dependent apoptosis

Kombucha, a fermented tea (KT) is claimed to possess many beneficial properties. Recent studies have suggested that KT prevents paracetamol and carbon tetrachloride-induced hepatotoxicity. We investigated the beneficial role of KT was against tertiary butyl hydroperoxide (TBHP) induced cytotoxicity and cell death in murine hepatocytes. TBHP is a well known reactive oxygen species (ROS) inducer, and it induces oxidative stress in organ pathophysiology. In our experiments, TBHP caused a reduction in cell viability, enhanced the membrane leakage and disturbed the intra-cellular antioxidant machineries while simultaneous treatment of the cells with KT and this ROS inducer maintained membrane integrity and prevented the alterations in the cellular antioxidant status. These findings led us to explore the detailed molecular mechanisms involved in the protective effect of KT. TBHP introduced apoptosis as the primary phenomena of cell death as evidenced by flow cytometric analyses. In addition, ROS generation, changes in the mitochondrial membrane potential, cytochrome c release, activation of caspases (3 and 9) and Apaf-1 were detected confirming involvement of mitochondrial pathway in this pathophysiology. Simultaneous treatment of KT with TBHP, on the other hand, protected the cells against oxidative injury and maintained their normal physiology.In conclusion, KT was found to modulate the oxidative stress induced apoptosis in murine hepatocytes probably due to its antioxidant activity and functioning via mitochondria dependent pathways and could be beneficial against liver diseases, where oxidative stress is known to play a crucial role.     

DNA damage in organs of mice treated acutely with patulin, a known mycotoxin

Patulin, a known mycotoxin, is considered a significant contaminant in apples, apple-derived products and feeds. This study investigated the genotoxic effects of patulin in multiple organs (brain, kidney, liver and urinary bladder) of mice using an in vivo comet assay. We assessed the mechanism underlying this genotoxicity by measuring the GSH content and the thiobarbituric acid-reactive species (TBARS) level. Male CF-1 mice were given 1.0-3.75mg/kg patulin intraperitoneally. The effect of patulin was dose-dependent and the highest patulin dose induced DNA strand breaks in the brain (damage index, DI, in hippocampus increased from 36.2 in control animals to 127.5), liver (44.3-138.4) and kidneys (31.5-99); decreased levels of GSH (hippocampus - from 46.9 to 18.4nmol/mg protein); and an increase in lipid peroxidation (hippocampus - from 5.8 to 20.3 MDA equivalents/mg protein). This finding establishes an interrelationship between the pro-oxidant and genotoxic effects of patulin. Pre-treatment administration of N-acetyl-cysteine reduced patulin-induced DNA damage (hippocampus - DI from 127.5 to 39.8) and lipid peroxidation (hippocampus - 20.3 to 12.8 MDA equivalents/mg protein) by restoring cellular GSH levels, reinforcing the positive relationship between patulin-induced GSH depletion and DNA damage caused by systemic administration of this mycotoxin.     

Lupeol protects against acetaminophen-induced oxidative stress and cell death in rat primary hepatocytes

Drug induced hepatotoxicity is a major problem where phytochemicals hold promise for its abrogation. This study was carried out to explore cytoprotective potential of lupeol, a triterpene, against acetaminophen (AAP)-induced toxicity in rat hepatocytes. AAP exposure significantly (p < 0.05) reduced cell viability, disturbed Bcl-2 family pro/anti-apoptotic protein balance, increased ROS production and altered redox homeostasis. It also induced mitochondria-mediated hepatocellular injury by significant mitochondrial depolarization, caspase-9/3 activation and subsequent DNA fragmentation. Our results suggest that lupeol pre-treatment effectively restored antioxidant enzyme levels, decreased lipid peroxidation, inhibited ROS generation and depolarization of mitochondria. Lupeol also attenuated mitochondria-mediated signaling pathway and DNA damage as evident from TUNEL assay and cell cycle studies leading to prevention of cytotoxicity. This study confirms the efficacy of lupeol, a food derived antioxidant, in abrogating ROS generation, maintaining redox balance and providing significant protection against mitochondria-mediated cell death during AAP-induced toxicity.     

Alpha-lipoic acid protects against myocardial ischemia/reperfusion injury via multiple target effects

Myocardial ischemia/reperfusion (MI/R) is a major cause for the events of cardiovascular disease. Oxidative stress plays a critical role in the development of ischemia/reperfusion (IR) injury. As a potent antioxidant, alpha-lipoic acid (LA) has been shown to provide a benefit for the inhibition of IR injury and inhibit reactive oxygen species (ROS) generation during MI/R in rats. However, the mechanism on the protective effect of LA is still to be clarified. The present study was aimed to investigate the protective effect of LA against MI/R injury and its mechanisms. We found that 2 h of myocardial ischemia followed by different time periods of reperfusion resulted in significant increase of creatine kinase (CK) activity. MI/R also significantly promoted oxidative stress and decreased the activities of antioxidant enzymes. In addition, apoptosis and inflammatory response were activated and aggravated in a time-dependent manner by MI/R. All these alterations induced by MI/R were attenuated by the administration of LA 30 min before reperfusion. These results suggested that LA played a protective effect against MI/R injury via antioxidant, anti-apoptotic and anti-inflammatory effects. These findings may significantly better the understanding of the pharmacological actions of LA and advance therapeutic approaches to MI/R injury and cardiovascular diseases.     

Toxicological studies on 2,4,6-tribromoanisole

TBA, or 2,4,6-tribromoanisole, is a musty-smelling metabolite of 2,4,6-tribromophenol that is used as a flame retardant and an antifungal agent for wooden pallets and packaging materials. The compound can impart its peculiar, often offensive, odor on product packaging to the concern of consumers for the safety of the package contents. These studies were conducted to evaluate the safety of TBA to humans ingesting products tainted with TBA. In addition to the 28-day oral study, a bacterial reverse mutation study was conducted, and confirmed that TBA was not mutagenic. To evaluate oral safety, TBA was evaluated in single dose and 5-day and 4-week repeated dose oral toxicity studies in rats. The test article, administered in single gavage doses of 2000, 5000 and 7500 mg/kg body weight (bw), in 5 daily repeated doses of 1000, 2000 or 3000 mg/kg bw/day or in 28 daily oral gavage doses of 0 001, 0.01, 100, and 1000 mg/kg bw/day did not result in any deaths. Also, the single and repeat dose studies resulted in no significant differences between control and treated groups on body weight gain, food consumption, clinical observations, blood biochemical values, and hematology findings. Treatment-related adverse findings were only detected in male rats during repeated dose studies and were associated with high plasma concentrations of TBA. The test article-related finding of hyaline droplets in the cortical tubular epithelium of kidneys was associated with increases in α_2μ-globulin content in the kidneys as indicated by the intensity of immunohistochemical staining. These findings were correlated with an increased weight of kidneys in males administered 1000 mg/kg bw/day for 28 days. Chemical induction of hyaline droplets containing α_2μ-globulin in the renal proximal tubule is a process unique to the male rat and is not relevant for human risk assessment. Findings of increased liver weight with minimal centrilobular to diffuse hepatocellular hypertrophy in males treated with TBA at 1000 mg/kg bw/day for 28 days were considered to be an adaptive metabolic response to xenobiotic administration. The increased volume of urine, noted in both males and females treated with 1000 mg/kg bw/day was considered adaptive and necessary to excrete the high xenobiotic burden resulting from TBA administration. TBA appeared to be highly bioavailable since high concentrations of TBA were detected in plasma, at 1, 4 and 8 h after administration of TBA at 100 and 1000 mg/kg bw for 1 and 28 days. Levels were dose-related but did not clarify the course of TBA elimination with time after administration. These studies indicate that TBA, administered orally to rats, produced male rat-specific, treatment-related toxicity at the highest orally administered dose in repeated dose (5-day at 3000 mg/kg bw and 28-day at 1000 mg/kg bw) studies. Therefore, the NOAEL for the 28-day oral study was determined to be 1000 mg/kg bw/day for the rat.     

Hepatoprotective effect of ethanolic extract of Phyllanthus amarus Schum. et Thonn. on aflatoxin B1-induced liver damage in mice

Phyllanthus amarus Schum. et Thonn. (Bhuia amla; Euphorbiacae) is a herb common to central and southern India. It is an ayurvedic herb and has a wide range of traditional uses in different diseases. The aim of this work was to evaluate the hepatoprotective effect of ethanolic extract of Phyllanthus amarus (Phyllanthus amarus) on aflatoxin B(1)-induced liver damage in mice using different biochemical parameters and histopathological studies. Aflatoxin was administered orally (66.6 microg kg(-1)BW 0.2 ml(-1)day(-1)) to the mice of each group except control to which normal saline and ascorbic acid (0.1g kg(-1)BW 0.2 ml(-1)day(-1)) were given, respectively. Ethanolic extract of Phyllanthus amarus (0.3g kg(-1)BW 0.2 ml(-1)day(-1)) was given to all groups except control groups (gp. I and gp. V) after 30 min of aflatoxin administration. The entire study was carried out for 3 months and animals were sacrificed after an interval of 30 days till the completion of study. Phyllanthus amarus extract was found to show hepatoprotective effect by lowering down the content of thiobarbituric acid reactive substances (TBARS) and enhancing the reduced glutathione level and the activities of antioxidant enzymes, glutathione peroxidase (GPx), glutathione-S-transferase (GST), superoxide dismutase (SOD) and catalase (CAT). Histopathological analyses of liver samples also confirmed the hepatoprotective value and antioxidant activity of the ethanolic extract of the herb, which was comparable to the standard antioxidant, ascorbic acid. The overall data indicated that Phyllanthus amarus possesses a potent protective effect against aflatoxin B(1)-induced hepatic damage, and the main mechanism involved in the protection could be associated with its strong capability to reduce the intracellular level of reactive oxygen species by enhancing the level of both enzymatic and non-enzymatic antioxidants.