DRDE-07 and its analogues as promising cytoprotectants to nitrogen mustard (HN-2)—An alkylating anticancer and chemical warfare agent

Nitrogen mustard (HN-2), also known as mechlorethamine, is an alkylating anticancer agent as well as blister inducing chemical warfare agent. We evaluated the cytoprotective efficacy of amifostine, DRDE-07 and their analogues, and other antidotes of mustard agents against HN-2. Administration of 1 LD₅₀ of HN-2 (20 mg/kg) percutaneously, decreased WBC count from 24 h onwards. Liver glutathione (GSH) level decreased prominently and the maximum depletion was observed on 7th day post-HN-2 administration. Oxidised glutathione (GSSG) level increased significantly at 24 h post-administration and subsequently showed a progressive decrease. Hepatic malondialdehyde (MDA) level and percent DNA damage increased progressively following HN-2 administration. The spleen weight decreased progressively and reached a minimum on 3–4 days with subsequent increase. The antidotes were administered repeatedly for 4 and 8 days after percutaneous administration of single sublethal dose (0.5 and 0.25 LD₅₀) of HN-2. Treatment with DRDE-07, DRDE-30 and DRDE-35 significantly protected the changes in spleen weight, WBC count, GSH, GSSG, MDA and DNA damage following HN-2 administration (0.5 and 0.25 LD₅₀). There was no alteration in the transaminases (AST and ALT), and alkaline phosphatase (ALP) activities, neither with HN-2 nor with antidotes. The present study shows that HN-2 is highly toxic by percutaneous route and DRDE-07, DRDE-30 and DRDE-35 can partially protect it.     

Functional and inflammatory alterations in the lung following exposure of rats to nitrogen mustard

Nitrogen mustard is a vesicant that causes damage to the respiratory tract. In these studies, we characterized the acute effects of nitrogen mustard on lung structure, inflammatory mediator expression, and pulmonary function, with the goal of identifying mediators potentially involved in toxicity. Treatment of rats (male Wistar, 200-225 g) with nitrogen mustard (mechlorethamine hydrochloride, i.t., 0.25 mg/kg) resulted in marked histological changes in the respiratory tract, including necrotizing bronchiolitis, thickening of alveolar septa, and inflammation which was evident within 24 h. This was associated with increases in bronchoalveolar lavage protein and cells, confirming injury to alveolar epithelial regions of the lung. Nitrogen mustard administration also resulted in increased expression of inducible nitric oxide synthase and cyclooxygenase-2, pro-inflammatory proteins implicated in lung injury, in alveolar macrophages and alveolar and bronchial epithelial cells. Expression of connective tissue growth factor and matrix metalloproteinase-9, mediators regulating extracellular matrix turnover was also increased, suggesting that pathways leading to chronic lung disease are initiated early in the pathogenic process. Following nitrogen mustard exposure, alterations in lung mechanics and function were also observed. These included decreases in baseline static compliance, end-tidal volume and airway resistance, and a pronounced loss of methacholine responsiveness in resistance, tissue damping and elastance. Taken together, these data demonstrate that nitrogen mustard induces rapid structural and inflammatory changes in the lung which are associated with altered lung functioning. Understanding the nature of the injury induced by nitrogen mustard and related analogs may aid in the development of efficacious therapies for treatment of pulmonary injury resulting from exposure to vesicants.     

The generation of 4-hydroxynonenal,an electrophilic lipid peroxidation end product,in rabbit cornea organ cultures treated with UVB light and nitrogen mustard

The cornea is highly sensitive to oxidative stress, a process that can lead to lipid peroxidation. Ultraviolet light B (UVB) and nitrogen mustard (mechlorethamine) are corneal toxicants known to induce oxidative stress. Using a rabbit air-lifted corneal organ culture model, the oxidative stress responses to these toxicants in the corneal epithelium was characterized. Treatment of the cornea with UVB (0.5 J/cm²) or nitrogen mustard (100 nmol) resulted in the generation of 4-hydroxynonenal (4-HNE), a reactive lipid peroxidation end product. This was associated with increased expression of the antioxidant, heme oxygenase-1 (HO-1). In human corneal epithelial cells in culture, addition of 4-HNE or 9-nitrooleic acid, a reactive nitrolipid formed during nitrosative stress, caused a time-dependent induction of HO-1 mRNA and protein; maximal responses were evident after 10 h with 30 μM 4-HNE or 6 h with 10 μM 9-nitrooleic acid. 4-HNE and 9-nitrooleic acid were also found to activate Erk1/2, JNK and p38 MAP kinases, as well as phosphoinositide-3-kinase (PI3)/Akt. Inhibition of p38 blocked 4-HNE- and 9-nitrooleic acid-induced HO-1 expression. Inhibition of Erk1/2, and to a lesser extent, JNK and PI3K/Akt, suppressed only 4-HNE-induced HO-1, while inhibition of JNK and PI3K/Akt, but not Erk1/2, partly reduced 9-nitrooleic acid-induced HO-1. These data indicate that the actions of 4-HNE and 9-nitrooleic acid on corneal epithelial cells are distinct. The sensitivity of corneal epithelial cells to oxidative stress may be an important mechanism mediating tissue injury induced by UVB or nitrogen mustard.     

新型氮芥衍生物XHH诱导K562细胞凋亡的研究

目的探讨新型氮芥衍生物N-[4-(二氯乙基)丁胺]-1,8-萘酰亚胺(XHH)对K562细胞的抗肿瘤作用及其机制。方法采用MTT法检测XHH对K562细胞增殖的影响;用Annexin V-FITC/Hoechst33342、PI/Hoechst33342和Rh123/Hoechst33342双染法高内涵观察细胞的形态学变化、凋亡率及线粒体膜电位;用分光光度法检测caspase-3、caspase-9的活性。结果在一定浓度范围内,XHH能抑制K562细胞的增殖且抗肿瘤活性优于美法仑,呈剂量和时间依赖性地诱导细胞凋亡、降低线粒体膜电位、活化caspase-3和caspase-9。结论 XHH具有较好的抗肿瘤活性,可通过线粒体/caspase-9/caspase-3途径诱导K562细胞凋亡。     

The effect of sulfur mustard and nitrogen mustard on corneal collagen degradation induced by the enzyme collagenase

Objective: Sulfur mustard (SM) is an alkylating agent that can affect cornea and induce various complications. With regard to the role of the enzyme collagenase in dermatologic complications induced by SM and its role in other ocular disorders, we studied the effect of SM and nitrogen mustard (NM) on collagen degradation by collagenase.

Materials and methods: This study included 7 groups of samples: The negative control group contained collagen without collagenase and toxins, the control group contained collagen and collagenase without any toxin, the positive control groups of NM and SM contained collagen and NM or SM without collagenase, the experimental groups of NM and SM contained collagen that was affected by NM or SM and collagenase, and the control group of collagenase contained only collagenase without containing collagen or receiving toxins. After incubation for 3.5 hours, the amount of hydroxyproline and the protein content of the samples were measured. Data were analyzed by analysis of variance (ANOVA).

Results: The protein concentrations of the negative control group and the positive control groups of SM and NM were significantly lower than those for all other groups of the study. There was a significant difference in hydroxyproline concentration of control group and negative control group; however, there was no significant difference between experimental group of SM and the positive conrol group of SM. There was no significant difference between the negative control group and the positive control group of SM in the hydroxyproline concentration of sediment samples.

Conclusion: According to the results of this study, SM can affect the corneal collagen in a way in which collagenase cannot degrade it. In addition, it can be hypothesized that ineffective activity of this enzyme can result in increasing concentration of collagenase, which can lead to the destruction of the normal collagen of the cornea. The main result of this study confirms the hypothesis that SM inhibits the effect of collagenase on corneal collagen.     

Morphological and biochemical correlates of chemical induced injury in the lung

We have reviewed some of the factors which contribute to lung damage by various toxicants. These include disposition of the chemical, its metabolism, individual cell type susceptibility and the potential for the tissue to repair. We have discussed the use of biochemical parameters to measure the functional activity of individual cell types in order to predict the damage to specific cell types and concluded that careful morphological analysis of lung tissue is likely to provide a more sensitive and informative measure of specific cell type injury. However, in order to investigate the mechanism of toxicity of pulmonary toxicants it is essential to establish the primary biochemical event that leads to cell damage and morphological change. The importance of separating the relevant biochemical change(s) from the cascade of biochemical events associated with dead and dying cells and the reparative response of the lung is emphasised.This report results from a discussion sponsored and organised by the Advisory Subgroup in Toxicology (AST) of the European Science Foundation's Standing Committee for the European Medical Research Councils and held at the Medical Research Council Toxicology Unit, Carshalton, U. K. Those taking part were: W. N. Aldridge (AST; as above); J. Bignon (Unit for Research in Renal and Pulmonary Pathology, University of Paris, Creteil, France); P. H. Burri (Section of Developmental Biology, Institute of Anatomy, University of Berne, Switzerland); G. M. Cohen (as above); D. Dinsdale (MRC Toxicology Unit, Carshalton U. K.); P. Hedqvist (Dept. of Physiology, Karolinska Institute, Stockholm, Sweden); D. Henschler (AST; Dept. of Toxicology and Pharmacology, University of Wurzburg, FDR); G. J. Laurent (Biochemistry Unit, Cardiothoracic Institute, University of London, London, U. K.); R. Lauwerys (AST Industrial and Medical Toxicology Unit, University of Louvain, Brussels, Belgium); F. Lembeck (AST; Dept. for Experimental and Clinical Pharmacology, University of Graz, Austria); N. Lery (AST; Poison Control Centre, Lyon, France); P. Moldeus (Dept. of Forensic Medicine, Karolinska Institute, Stockholm, Sweden); B. Nemery (MRC Toxicology Unit, Carshalton, U. K.); A. Saria (Dept. for Experimental and Clinical Pharmacology, University of Graz, Austria); L. L. Smith (as above);B. Terracini (AST; Dept. of Pathology and Cancer Epidemiology, University of Turin, Italy)     

Sulfur mustard causes oxidants/antioxidants imbalance through the overexpression of free radical producing-related genes in human mustard lungs

The aim of this study is to analyze oxidative stress (OS) and changes in expression of reactive oxygen species (ROS) producing-related genes in mustard lungs. Human lung biopsies provided from controls (n = 5) and sulfur mustard (SM)-exposed patients (n = 6). Changes in expression of dual oxidases (DUOXs), aldehyde oxidase 1 (AOX1), thyroid peroxidase (TPO), myeloperoxidase (MPO) and eosinophil Peroxidase (EPO) were measured using RT² Profiler™ PCR Array. OS was evaluated by determining bronchoalveolar lavage fluids (BALF) levels of total antioxidant capacity (TAC) and malondialdehyde (MDA). Higher TAC value was observed in BALF of controls compared with patients (0.138 ± 0.02683 μmol/l vs 0.0942 ± 0.01793 μmol/l), whereas a significant increase in MDA concentration was found in patients (0.486 ± 0.04615 nmol/l vs 0.6467 ± 0.05922 nmol/l). All ROS producing-related genes were overexpressed in the order AOX1> MPO> DUOX2> DUOX1> TPO> EPO. Upregulation of these genes may be a reason for overproduction of ROS, oxidants/antioxidants imbalance, OS and respiratory failures in mustard lungs.     

Oxidative stress and oxidative damage in chemical carcinogenesis

Reactive oxygen species (ROS) are induced through a variety of endogenous and exogenous sources. Overwhelming of antioxidant and DNA repair mechanisms in the cell by ROS may result in oxidative stress and oxidative damage to the cell. This resulting oxidative stress can damage critical cellular macromolecules and/or modulate gene expression pathways. Cancer induction by chemical and physical agents involves a multi-step process. This process includes multiple molecular and cellular events to transform a normal cell to a malignant neoplastic cell. Oxidative damage resulting from ROS generation can participate in all stages of the cancer process. An association of ROS generation and human cancer induction has been shown. It appears that oxidative stress may both cause as well as modify the cancer process. Recently association between polymorphisms in oxidative DNA repair genes and antioxidant genes (single nucleotide polymorphisms) and human cancer susceptibility has been shown.     

Synthesis of 13C labeled sulfur and nitrogen mustard metabolites as mass spectrometry standards for monitoring and detecting chemical warfare agents

¹³C labeled (>M + 4) metabolites of nitrogen and sulfur‐based chemical warfare agent metabolites were prepared from readily available and ¹³C labeled commercial starting materials. The new chemical routes are efficient in the number of chemical steps, can be scaled to afford gram quantities, and occur in good yields on the basis of the ¹³C label. These labeled compounds are useful as internal standards in mass spectrometry for monitoring chemical warfare agents and their metabolites. Published 2012. This article is a US Government work and is in the public domain in the USA.     

Efficacy of diphenyl diselenide against cerebral and pulmonary damage induced by cadmium in mice

This study was designed to examine if diphenyl diselenide (PhSe)(2), an organoselenium compound, attenuates pulmonar and cerebral oxidative stress caused by sub-chronic exposure to CdCl(2). Male adult Swiss albino mice received CdCl(2) (10 micromol/kg, subcutaneously), 5 times/week, for 4 weeks. (PhSe)(2) (10 micromol/kg or 20 micromol/kg, orally) was given concomitantly with CdCl(2) to mice. A number of toxicological parameters in lung and brain of mice were examined including delta-aminolevulinic acid dehydratase (delta-ALA-D), superoxide dismutase (SOD) and catalase activities, lipid peroxidation, non-protein thiols (NPSH) and ascorbic acid content. Na(+),K(+)-ATPase activity, acetylcholinesterase (AChE) activity, [(3)H]glutamate uptake and [(3)H]glutamate release were also carried out in brain. Cadmium concentration and histopathological analysis were carried out in lung tissue. (PhSe)(2) at the dose of 20 micromol/kg protected the inhibition of delta-ALA-D, SOD and CAT activities, the reduction of vitamin C content and the increase of lipid peroxidation levels caused by CdCl(2) in lungs. At 10 micromol/kg, (PhSe)(2) protected cerebral AChE and CAT activities inhibited by CdCl(2). There were no histopathological alterations in the lung of mice after CdCl(2) exposure. The pulmonary cadmium concentration was higher (2.8-fold) in the group exposed to CdCl(2) than in control mice. (PhSe)(2) at dose of 20 micromol/kg reduced cadmium concentration towards the control level. The results suggest that oral administration of (PhSe)(2) attenuated the oxidative damage induced by CdCl(2) in lung and brain of mice.     

Melatonin treatment against remote organ injury induced by renal ischemia reperfusion injury in diabetes mellitus

Oxidative stress may have a role in liver damage after acute renal injury due to various reasons such as ischemia reperfusion (IR). Diabetes mellitus (DM) is an important disease for kidneys and may cause nephropathy as a long term complication. The aim of this study was to investigate protective effect of melatonin, a potent antioxidant, against distant organ injury on liver induced by renal IR in rats with or without DM. The rats were divided into six groups: control (n=7), DM (n=5), IR (n=7), DM+IR (n=7), melatonin+IR (Mel+IR) (melatonin, 4 mg/ kg during 15 days) (n=7), and Mel+DM+IR groups (n=7). Diabetes developed 3 days after single i.p. dose of 45 mg/kg streptozotocin. After 15 day, the left renal artery was occluded for 30 min followed 24 h of reperfusion in IR performed groups. DM did not alter oxidative parameters alone in liver tissue. The levels of malondialdehyde, protein carbonyl and nitric oxide with activities of xanthine oxidase and myeloperoxidase were increased in liver tissues of diabetic and non-diabetic IR groups. Nitric oxide level in DM was higher than control. The activities of catalase and superoxide dismutase were increased in IR groups in comparison with control and DM. ALT and AST levels were higher in IR and DM+IR groups than control and DM. Melatonin treatment reversed all these oxidant and antioxidant parameters to control values as well as serum liver enzymes. We concluded that renal IR may affect distant organs such as liver and oxidative stress may play role on this injury, but DM has not an effect on kidney induced distant organ injury via oxidant stress. Also, it was concluded that melatonin treatment may prevent liver oxidant stress induced by distant injury of kidney IR.     

Melatonin alleviates memory deficits and neuronal degeneration induced by intracerebroventricular administration of streptozotocin in rats

In the present study the effect of melatonin on intracerebroventricularly administered streptozotocin (STZ)-induced neurodegeneration was investigated in rats. STZ (3 mg/kg), administered twice with an interval of 48 h between the two doses, showed impairment in spatial memory tested by water maze test after 14 days of 1st dose. Administration of melatonin (2.5, 5.0 and 10 mg/kg, i.p.) was started 1 h prior to 1st dose of STZ and continued up to 14 days. Glutathione and malondialdehyde were used as biochemical markers of oxidative stress in different brain regions. Histopathological changes were examined by using hematoxylin and eosin stain. STZ administration caused significant decrease in glutathione and increase in malondialdehyde as compared to control and artificial Cerebrospinal Fluid treated rats indicating oxidative stress. Brain sections of STZ-treated rats showed increased vacuoles in the periventricular cortical area, damaged periventricular cells and damaged cells in the hippocampal CA4 region as compared to control and artificial Cerebrospinal Fluid treated groups. Melatonin treatment significantly attenuated the effect of STZ-induced oxidative stress and histopathological changes. The results indicate that melatonin is effective in providing protection against memory deficit, oxidative stress and neuronal damage induced by STZ.     

Melatonin reduces oxidative damage induced by aluminium in rat kidney

We evaluated the effect of melatonin (Mel), in male Wistar rats which received aluminium (Al) lactate for 12 weeks (0.57 mg Al/100 g body weight (b.w.), i.p. three times per week). Moreover rats received Mel (10 mg/kg b.w. i.p. 5 days/weeks) for 12 weeks. At the end of the treatment water and sodium balances were studied, and nephrogenic cyclic adenosine monophosphate (cAMP) was also measured. Urinary osmolality was measured after the administration of desmopressin (vasopressin agonist) to assess concentrating capacity. Oxidative stress in renal tissue and Na⁺–K⁺ATPase and gamma-glutamyl transferase (GGT) activities in whole plasma membrane were determined. Sodium and water balances were impaired by Al. We found decreased urinary concentrating ability and nephrogenic cAMP excretion. Al increased the Na⁺–K⁺ATPase activity, and serum aldosterone concentration. Mel normalized serum aldosterone level, the Na⁺–K⁺ATPase activity and potassium urinary without improving water and sodium excretion. Mel treatment did not improve the impaired urinary concentrating ability. Al reduced the GGT activity, an effect that persists in Al⁺ Mel. Al exposure promoted oxidative stress with an increase in lipid peroxidation (LPO), and a decrease in glutathione (GSH) and glutathione peroxidase (GSH-Px) and catalase (CAT) activities. Mel markedly attenuated oxidative stress produced by Al. This may result from the higher efficacy of melatonin in scavenging various free radicals and also because of its ability in stimulating the antioxidant enzymes. However, it only reduced some alterations in the renal functions particularly related to the water and sodium excretion, which would be independent of the increased production of reactive oxygen substances.     

Detection of key enzymes,free radical reaction products and activated signaling molecules as biomarkers of cell damage induced by benzo[a]pyrene in human keratinocytes

Benzo[a]pyrene (BaP) is a known carcinogenic and cell damaging agent. The underlying cell damaging pathomechanisms have not been totally revealed. Especially BaP-related induction of oxidative and nitrosative stress has not been previously investigated in detail. The presented study investigated these effects in order to elucidate the pathomechanism and as well to identify potential biological markers that may indicate a BaP exposure. Human immortalized keratinocytes (HaCaT cells) were exposed to BaP (1 μM) for either 5 min or 6 h, respectively. BaP-induced cellular damage was evaluated by immunocytochemistry analysis of multiple signaling cascades (e.g. apoptosis, Akt, MAPK, NOS, nitrotyrosine and 8-isoprostane formation), detection of nitrosative stress using diaminofluorescein (DAF-FM) and oxidative stress using 3′ -(p-aminophenyl)fluorescein (APF).Our results show that BaP exposure significantly enhanced NO and ROS productions in HaCaT cells. BaP led to eNOS-phosphorylation at Ser¹¹⁷⁷, Thr⁴⁹⁵ and Ser¹¹⁶ residues. Using specific inhibitors, we found that the Erk1/2 pathways seemed to have strong impact on eNOS phosphorylation. In addition, BaP-induced apoptosis was observed by caspase-3 activation and PARP cleavage.Our results suggest that BaP mediates its toxic effect in keratinocytes through oxidative and nitrosative stress which is accompanied by complex changes of eNOS phosphorylation and changes of Akt and MAPK pathways.     

Effects of neuropeptide S on seizures and oxidative damage induced by pentylenetetrazole in mice

Neuropeptide S (NPS) and its receptor were recently discovered in the central nervous system. In rodents, NPS promotes hyperlocomotion, wakefulness, anxiolysis, anorexia, and analgesia and enhances memory when injected intracerebroventricularly (i.c.v.). Herein, NPS at different doses (0.01, 0.1 and 1 nmol) was i.c.v. administered in mice challenged with pentylenetetrazole (PTZ; 60 mg/kg) repeatedly injected. Aiming to assess behavioral alterations and oxidative damage to macromolecules in the brain, NPS was injected 5 min prior to the last dose of PTZ. The administration of NPS only at 1 nmol increased the duration of seizures evoked by PTZ, without modifying frequency and latency of seizures. Biochemical analysis revealed that NPS attenuated PTZ-induced oxidative damage to proteins and lipids in the hippocampus and cerebral cortex. In contrast, the administration of NPS to PTZ-treated mice increased DNA damage in the hippocampus, but not cerebral cortex. In conclusion, this is the first evidence of the potential proconvulsive effects of NPS in mice. The protective effects of NPS against lipid and protein oxidative damage in the mouse hippocampus and cerebral cortex evoked by PTZ-induced seizures are quite unexpected. The present findings were discussed analyzing the paradoxical effects of NPS: facilitation of convulsive behavior and protection against oxidative damage to lipids and proteins.     

Defining the timing of 25(OH)D rescue following nitrogen mustard exposure

Objective: Mass exposure to alkylating agents such as nitrogen mustard (NM), whether accidental or intentional as during warfare, are known to cause systemic toxicity and severe blistering from cutaneous exposure. Thus, establishing the timing and appropriate dose of any potential drug designed to reverse or impede these toxicities is critical for wound repair and survival. Our previous data demonstrates that a single intraperitoneal injection of low-dose 25-hydroxyvitamin D3 (25(OH)D) given as early as 1?h following NM exposure is sufficient to rescue mice from pancytopenia and death. However, the duration of time following exposure where intervention is still effective as a countermeasure is unknown. In this study, we sought to assess the maximal time permissible following NM exposure where 25(OH)D still affords protection against NM-induced cutaneous injury. Additionally, we determined if a higher dose of 25(OH)D would be more efficacious at time interval where low dose 25(OH)D is no longer effective.

Methods: Low (5?ng) and high (50?ng) doses of 25(OH)D were administered intraperitoneally to mice following exposure to topical NM to assess wound resolution and survival. Mice were imaged and weighed daily to measure wound healing and to monitor systemic toxicity.

Results: We demonstrated that 5?ng 25(OH)D administered as early as 1?h and as late as 24?h post-NM exposure is able to achieve 100% recovery in mice. In contrast, intervention at and beyond 48?h of NM exposure failed to achieve full recovery and resulted in ≥60% death between days 6 and 12, demonstrating the critical nature of timely intervention with 25(OH)D at each respective dose. In order to circumvent the observed failure at >48?h exposure, we provided two consecutive doses of 5?ng or 50?ng of 25(OH)D at 48?h and 72?h post-NM exposure. Repeat dosing with 25(OH)D at 48?h and beyond led to marked improvement of lesion size with 75% recovery from mortality.

Conclusions: The opportunity to use 25(OH)D as a medical countermeasure for NM-induced toxicity has a finite of window for intervention. However, modifications such as repeat dosing can be an effective strategy to extend the intervention potential of 25(OH)D.     

Thymoquinone effectively alleviates lung fibrosis induced by paraquat herbicide through down-regulation of pro-fibrotic genes and inhibition of oxidative stress

The potential preventive and therapeutic effects of thymoquinone (TQ) and its molecular mechanism were evaluated in paraquat (PQ)-induced pulmonary fibrosis in mice. TQ was administered orally at the doses of 20 and 40 mg/kg during the course and after development of fibrosis. Pathological changes, expressions of genes involved in fibrogenesis, hydroxyproline (HP) and oxidative stress parameters were determined in the lung tissues. TQ dose-dependently recovered the pathological changes induced by PQ. TQ decreased hydroxyproline content, lipid peroxidation and restored the antioxidant enzymes to the normal values. In molecular level, expressions of TGF-β1, α-SMA, collagen 1a1 and collagen 4a1 genes were also returned to the control level by TQ. This study indicated that TQ has the preventive and therapeutic potentials for the treatment of lung fibrosis by inhibition of oxidative stress and down-regulation of profibrotic genes.     

The oxidative damage and inflammatory response induced by lead sulfide nanoparticles in rat lung

Lead sulfide nanoparticles (PbS NPs) are one important nanoparticle materials which is widely used in photoelectric production, but its potential health hazard to respiratory system is not clear. This study aimed to explore the possible mechanism of lung injury induced by PbS NPs. Male SD rats were treated with nanoparticles of 60 nm and 30 nm lead sulfide. The main methods were detecting the vigor of superoxide dismutase (SOD) and total antioxidant capacity (T-AOC) and the content of malondialdehyde (MDA) in both blood and lung tissues and observing the pathological changes in lung tissue. PbS NPs suppressed the activity of SOD and T-AOC, and increased serum MDA content (P < 0.05); both effects were observed together in lung tissues of 30-nm group (P < 0.05) accompanied by an obviously inflammatory response. PbS NPs induced oxidative damage and inflammatory response in lung tissue, which may be an underlying mechanism for its pulmonary toxicity. Additionally, the toxicity of PbS NPs was closely related with the size of nanoparticles.     

DNA damage,signalling and repair after exposure of cells to the sulphur mustard analogue 2-chloroethyl ethyl sulphide

Sulphur mustard (SM) is a blistering agent that is directly toxic to the skin and mucosal surfaces of the eye and respiratory system. Symptoms take several hours to develop and the mechanism of action is poorly understood although SM is able to alkylate nucleic acids and proteins. The ability of SM to form adducts with DNA has been documented, although there are limited data demonstrating how cells respond to this insult to repair the damage. This study used the sulphur mustard surrogate 2-chloroethyl ethyl sulphide (CEES) to identify DNA damage repair pathways and signalling events that are activated after exposure to the agent. A dose-dependent increase in DNA damage was observed in TK6 lymphoblastoid cells, which was associated with a loss of cell viability. Using both model human lymphoblastoid cell lines and pharmacological inhibitors, it was found that DNA damage induced by CEES was repaired by base excision repair (BER) and nucleotide excision repair (NER) pathways. Finally, CEES was found to induce the phosphorylation of p53 and Chk2 and these events were mediated by both the ATM ataxia telangiectasia mutated and ATR (ATM and Rad-3 related) protein kinases.