N-acetyl-L-cystein Research Articles

Proteome-wide analysis reveals molecular pathways affected by AgNP in a ROS-dependent manner

The use of mass spectrometry-based proteomics has been increasingly applied in nanomaterials risk assessments as it provides a proteome-wide overview of the molecular disturbances induced by its exposure. Here, we used this technique to gain detailed molecular insights into the role of ROS as an effector of AgNP toxicity, by incubating Bend3 cells with AgNP in the absence or presence of an antioxidant N-acetyl L-cystein (NAC). ROS generation is a key player in AgNP-induced toxicity, as cellular homeostasis was kept in the presence of NAC. By integrating MS/MS data with bioinformatics tools, in the absence of NAC, we were able to pinpoint precisely which biological pathways were affected by AgNP. Cells respond to AgNP-induced ROS generation by increasing their antioxidant pool, via NRF2 pathway activation. Additionally, cell proliferation-related pathways were strongly inhibited in a ROS-dependent manner. These findings reveal important aspects of the AgNP mechanism of action at the protein level.

Bavachin Induces Apoptosis through Mitochondrial Regulated ER Stress Pathway in HepG2 Cells.

As a traditional herbal medicine, the fruits of Psoralea corylifolia L. (Fructus Psoraleae (FP)) have been widely used for the treatment of various skin diseases for hundred years. Recently, the emerging FP-induced toxic effects, especially hepatotoxicity, in clinic are getting the public's attention. However, its exact toxic components and mechanisms underlying remain unclear. Bavachin, one of flavonoids in FP, has been documented as a hepatotoxic substance, and the present study aimed to determine the toxicity caused by bavachin and the possible toxic mechanisms involved using human hepatocellular carcinoma (HepG2) cells. Our results showed that bavachin could significantly inhibited cell proliferation and trigger the endoplasmic reticulum (ER) stress in a dose dependent manner. Downregulating ER stress using tauroursodeoxycholic acid (TUDCA) obvious attenuated bavachin-triggerd cell apoptosis. Then, small interfering RNA (siRNA) knock-down of Mitofusion2 (Mfn2) resulted in a remarkable aggravation of ER stress through the inhibition of the phosphorylation of protein kinase B (Akt). Additionally, suppression of reactive oxygen species (ROS) by ROS Scavenger (N-acetyl-l-cystein (NAC)) also reduced bavachin-induced ER stress. Taken together, our study demonstrated that bavachin-induced ER stress caused cell apoptosis by Mfn2-Akt pathway, and that ROS may participate upstream in this mechanism. Here, we not only provide a new understanding of ROS/Mfn2/Akt pathway in bavachin-induced cytotoxicity via the ER stress, but also identify a new specific intervention to prevent FP-induced hepatotoxicity in the future.

PM2.5 exposure stimulates COX-2-mediated excitatory synaptic transmission via ROS-NF-κB pathway

Long-term exposure to fine particulate matter (PM2.5) has been reported to be closely associated with the neuroinflammation and synaptic dysfunction, but the mechanisms underlying the process remain unclear. Cyclooxygenase-2 (COX-2) is a key player in neuroinflammation, and has been also implicated in the glutamatergic excitotoxicity and synaptic plasticity. Thus, we hypothesized that COX-2 was involved in PM2.5-promoted neuroinflammation and synaptic dysfunction. Our results revealed that PM2.5 elevated COX-2 expression in primary cultured hippocampal neurons and increased the amplitude of field excitatory postsynaptic potentials (fEPSPs) in hippocampal brain slices. And the administration of NS398 (a COX-2 inhibitor) prevented the increased fEPSPs. PM2.5 also induced intracellular reactive oxygen species (ROS) generation accompanied with glutathione (GSH) depletion and the loss of mitochondrial membrane potential (MMP), and the ROS inhibitor, N-acetyl-L-cystein (NAC) suppressed the COX-2 overexpression and the increased fEPSPs. Furthermore, the nuclear factor kappa B (NF-κB) was involved in ROS-induced COX-2 and fEPSP in response to PM2.5 exposure. These findings indicated that PM2.5 activated COX-2 expression and enhanced the synaptic transmission through ROS-NF-κB pathway, and provided possible biomarkers and specific interventions for PM2.5-induced neurological damage.

Simultaneous and selective measurement of dopamine and uric acid using glassy carbon electrodes modified with a complex of gold nanoparticles and multiwall carbon nanotubes

Abnormal levels of dopamine and uric acid are closely relative to some diseases of human body and can serve as key indicators for human health monitoring. As the primary products of purine metabolism, dopamine and uric acid generally coexist in the extracellular fluid of central nervous system and serum. The sensitive and simultaneous analysis of dopamine and uric acid is urgent in clinical diagnosis of some diseases. Herein, carboxylated-multiwall carbon nanotubes (MWCNTs) were functionalized with N-acetyl-l-cystein (NAC) stabilized Au clusters to generate Au@NAC- MWCNTs complex. By drop-coating the complex on glassy carbon electrode (GCE) surface, the complex-modified GCE was fabricated and used for a new working electrode for electrochemical sensing applications. Using cyclic voltammetry and differential pulse voltammetry measurements, the complex-modified GCE showed the capacity of highly sensitive, individual, and simultaneous electrochemical sensing of dopamine and uric acid. The linear detection ranges of dopamine and uric acid were 0.1–250μM and 0.1–300μM, respectively, accompanied by low detection limits of 30nM of dopamine and 40nM uric acid. In real human serum and urine samples, the complex- modified GCE exhibited a high performance for simultaneous and selective detection of dopamine and uric acid, together with high detection recoveries of 96.9–104.7% and low relative standard deviation of 1.1–3.7%.

Clinical Performances of Pure TB-Lamp Kit for <i>M. tuberculosis</i> Complex Detection in Sputum Samples

Tuberculosis represents a main concern for public health worldwide. In poor countries, the most prevalent method for bacteriological confirmation re- mains Smear Sputum Microscopy (SSM). This study objective was to assess clinical performances of Loop Mediated Isothermal Amplification for TB detection (Lamp-TB). Sputum of patients presenting symptoms consistent with tuberculosis were collected according to the National Tuberculosis Control Programme guidelines in Centre Antituberculeux de Yopougon. SSM after Ziehl-Neelsen staining and TB-Lamp were blindly performed with spot sputum specimen. Samples, transported at Institut Pasteur de Cote d’Ivoire were decontaminated according to N-acetyl-L-cystein (NALC) method. In Mycobacteria Growth Indicator Tube (MGIT), 500 μl of pellet were inoculated and incubated in MGIT 960 instrument. MPT64 antigen was detected on positive culture. Of 500 patients enrolled, 469 were included. Clinical isolates of M. tuberculosis Complex were detected for 157 (33.5%). Comparatively to culture, Sensitivity and Specificity of SSM were 86% (95% Confidence interval (CI): 81% - 91%) 96% (95%IC: 94% - 98%) respectively. TB-Lamp Sensitivity was 92% (95%CI: 88% - 96%), and Specificity 94% (95%CI: 91% - 97%). Positive Predictive Value of SSM and TB-Lamp was 91.8% and 88.8% respectively. Negative Predictive Value of TB-Lamp assay was 95.7% whereas this of SSM was 93.3%. Positive Likelihood Ratio was 15.3 for TB-Lamp and 21.5 for SSM 21.5 whereas negative Likelihood of TB-Lamp was lower than SSM. Active tuberculosis was detected in162/469 (34.5%) with TB-Lamp and 147 (31.3%) with SSM. TB-Lamp assay performances estimated from sputum samples may improve detection of active TB cases in routine.

Cadmium induces matrix metalloproteinase-9 expression via ROS-dependent EGFR, NF-кB, and AP-1 pathways in human endothelial cells.

Cadmium (Cd), a widespread cumulative pollutant, is a known human carcinogen, associated with inflammation and tumors. Matrix metalloproteinase-9 (MMP-9) plays a pivotal role in tumor metastasis; however, the mechanisms underlying the MMP-9 expression induced by Cd remain obscure in human endothelial cells. Here, Cd elevated MMP-9 expression in dose- and time-dependent manners in human endothelial cells. Cd increased ROS production and the ROS-producing NADPH oxidase. Cd translocates p47(phox), a key subunit of NADPH oxidase, to the cell membrane. Cd also activated the phosphorylation of EGFR, Akt, Erk1/2, and JNK1/2 in addition to promoting NF-кB and AP-1 binding activities. Specific inhibitor and mutagenesis studies showed that EGFR, Akt, Erk1/2, JNK1/2 and transcription factors NF-κB and AP-1 were related to Cd-induced MMP-9 expression in endothelial cells. Akt, Erk1/2, and JNK1/2 functioned as upstream signals in the activation of NF-κB and AP-1, respectively. In addition, N-acetyl-l-cystein (NAC), diphenyleneiodonium chloride (DPI) and apocynin (APO) inhibited the Cd-induced activation of EGFR, Akt, Erk1/2, JNK1/2, and p38 MAPK, indicating that ROS production by NADPH oxidase is the furthest upstream signal in MMP-9 expression. At present, it states that Cd displayed marked invasiveness in ECV304 cells, which was partially abrogated by MMP-9 neutralizing antibodies. These results demonstrated that Cd induces MMP-9 expression via ROS-dependent EGFR->Erk1/2, JNK1/2->AP-1 and EGFR->Akt->NF-κB signaling pathways and, in turn, stimulates invasiveness in human endothelial cells.

Withaferin A-caused production of intracellular reactive oxygen species modulates apoptosis via PI3K/Akt and JNKinase in rabbit articular chondrocytes.

Withaferin A (WFA) is known as a constituent of Ayurvedic medicinal plant, Withania somnifera, and has been used for thousands of years. Although WFA has been used for the treatment of osteoarthritis (OA) and has a wide range of biochemical and pharmacologic activities, there are no findings suggesting its properties on chondrocytes or cartilage. The aim of the present study is to investigate the effects of WFA on apoptosis with focus on generation of intracellular reactive oxygen species (ROS). Here we showed that WFA significantly increased the generation of intracellular ROS in a dose-dependent manner. We also determined that WFA markedly leads to apoptosis as evidenced by accumulation of p53 by Western blot analysis. N-Acetyl-L-Cystein (NAC), an antioxidant, prevented WFA-caused expression of p53 and inhibited apoptosis of chondrocytes. We also found that WFA causes the activation of PI3K/Akt and JNKinase. Inhibition of PI3K/Akt and JNKinase with LY294002 (LY)/triciribine (TB) or SP600125 (SP) in WFA-treated cells reduced accumulation of p53 and inhibited fragmented DNA. Our findings suggested that apoptosis caused by WFA-induced intracellular ROS generation is regulated through PI3K/Akt and JNKinase in rabbit articular chondrocytes.Graphical

Rats with metabolic syndrome resist the protective effects of N-acetyl l-cystein against impaired spermatogenesis induced by high-phosphorus/zinc-free diet

Consumption of relatively high amounts of processed food can result in abnormal nutritional status, such as zinc deficiency or phosphorus excess. Moreover, hyperphosphatemia and hypozincemia are found in some patients with diabetic nephropathy and metabolic syndrome. The present study investigated the effects of high-phosphorus/zinc-free diet on the reproductive function of spontaneously hypertensive rats/NDmcr-cp (SHR/cp), a model of the metabolic syndrome. We also investigated the effects of antioxidant, N-acetyl-l-cysteine (NAC), on testicular dysfunction under such conditions. Male SHR/cp and control rats (Wistar Kyoto rats, WKY) were divided into three groups; rats fed control diet (P 0.3%, w/w; Zn 0.2%, w/w), high-phosphorus and zinc-deficient diet (P 1.2%, w/w; Zn 0.0%, w/w) with vehicle, or high-phosphorus and zinc-deficient diet with NAC (1.5mg/g/day) for 12 weeks (n=6 or 8 rats/group). The weights of testis and epididymis were significantly reduced by high-phosphate/zinc-free diet in both SHR/cp and WKY. The same diet significantly reduced caudal epididymal sperm count and motility and induced histopathological changes in the testis in both strains. Treatment with NAC provided significant protection against the toxic effects of the diet on testicular function in WKY, but not in SHR/cp. The lack of the protective effects of NAC on impaired spermatogenesis in SHR/cp could be due to the more pronounced state of oxidative stress observed in these rats compared with WKY.

Performance of Frontloading for Smear Microscopy in the Diagnosis of Pulmonary Tuberculosis: A Cross-Sectional Study at a Referral Hospital in Uganda

ObjectiveTo compare the performance of frontloading and the standard WHO method for diagnosis of pulmonary TB at Mulago Hospital in order to validate the technique in this setting.MethodsThis was a cross-sectional study in which 229 adult (≥18 years) TB suspects were consecutively enrolled. Suspects submitted three sputum samples as follows: at initial presentation, one hour after the first sample, and the next morning. The first and next morning samples formed the standard WHO method, while the first and the one hour later samples formed the frontloading method. Sample processing was by the standard N-acetyl L-cystein (NALC)-NaOH method, and fluorescent microscopy was done for both methods, while cultures of the first sample on Lowenstein-Jensen slants acted as a gold standard. The sensitivity, specificity and predictive values for the WHO standard and frontloading methods were compared.ResultsThe sensitivity of both the frontloading and standard schemes was 91.1% while their specificities were 86.2% and 91.7% respectively. There was excellent agreement between the diagnostic capacity of the two methods (kappa statistic = 0.87, P<0.0001). The positive predictive value for the frontloading scheme was 87.2% and that for the standard approach was 91.9%, while the negative predictive values were 90.4% and 90.9%, respectively. Among the HIV positive patients, frontloading identified 59/79 (74.7%) culture positive samples while the standard approach identified 55/79 (69.6%). In the HIV sero-negative category, on the other hand, front-loading identified 48/110 (43.6%) culture positive samples compared to 45/110 (40.9%) by the standard approach.ConclusionFrontloading based on smear examination of two same-day sputum samples has a similar performance to the current standard method and would not be associated with any significant missed diagnosis. It may therefore be advocated for use in our setting so as to reduce time to completion of diagnosis and patient loss to follow-up.

Hydrogen sulfide protects against chemical hypoxia-induced injury by inhibiting ROS-activated ERK1/2 and p38MAPK signaling pathways in PC12 cells.

Hydrogen sulfide (H2S) has been proposed as a novel neuromodulator and neuroprotective agent. Cobalt chloride (CoCl2) is a well-known hypoxia mimetic agent. We have demonstrated that H2S protects against CoCl2-induced injuries in PC12 cells. However, whether the members of mitogen-activated protein kinases (MAPK), in particular, extracellular signal-regulated kinase1/2(ERK1/2) and p38MAPK are involved in the neuroprotection of H2S against chemical hypoxia-induced injuries of PC12 cells is not understood. We observed that CoCl2 induced expression of transcriptional factor hypoxia-inducible factor-1 alpha (HIF-1α), decreased cystathionine-β synthase (CBS, a synthase of H2S) expression, and increased generation of reactive oxygen species (ROS), leading to injuries of the cells, evidenced by decrease in cell viability, dissipation of mitochondrial membrane potential (MMP) , caspase-3 activation and apoptosis, which were attenuated by pretreatment with NaHS (a donor of H2S) or N-acetyl-L cystein (NAC), a ROS scavenger. CoCl2 rapidly activated ERK1/2, p38MAPK and C-Jun N-terminal kinase (JNK). Inhibition of ERK1/2 or p38MAPK or JNK with kinase inhibitors (U0126 or SB203580 or SP600125, respectively) or genetic silencing of ERK1/2 or p38MAPK by RNAi (Si-ERK1/2 or Si-p38MAPK) significantly prevented CoCl2-induced injuries. Pretreatment with NaHS or NAC inhibited not only CoCl2-induced ROS production, but also phosphorylation of ERK1/2 and p38MAPK. Thus, we demonstrated that a concurrent activation of ERK1/2, p38MAPK and JNK participates in CoCl2-induced injuries and that H2S protects PC12 cells against chemical hypoxia-induced injuries by inhibition of ROS-activated ERK1/2 and p38MAPK pathways. Our results suggest that inhibitors of ERK1/2, p38MAPK and JNK or antioxidants may be useful for preventing and treating hypoxia-induced neuronal injury.

P,p′-Dichlorodiphenoxydichloroethylene induced apoptosis of Sertoli cells through oxidative stress-mediated p38 MAPK and mitochondrial pathway

p,p′-DDE, the major metabolite of dichlorodiphenoxytrichloroethane (DDT), is a known persistent organic pollutant and male reproductive toxicant. However, the mechanism underlying its male reproductive toxicity remains limited. Our previous studies have demonstrated that p,p′-DDE could induce mitochondria-mediated apoptosis of cultured rat Sertoli cells. In the present study, we investigated mitogen-activated protein kinase pathways as well as other mitochondria-related molecules including Bax family members and cytochrome c. Results showed that p,p′-DDE could induce oxidative stress-mediated p38 and JNK phosphorylation. In addition, elevated mRNA levels of cytochrome c and ratios of bax/bcl-w and bak/bcl-w were induced by p,p′-DDE treatment, which could be inhibited by RNA synthesis inhibitor (actinomycin D). p,p′-DDE-induced apoptosis was blocked by NAC (N-acetyl-L-cystein) preincubation and attenuated by pretreatment with p38 inhibitor (SB202190) or actinomycin D, but not with JNK inhibitor (SP600125). All of the findings suggested that oxidative stress-mediated p38 MAPK pathway and the balance between pro- and anti-apoptotic bax-gene family might play critical roles in p,p′-DDE-induced apoptosis.

Oxidation of Cell Surface Thiol Groups by Contact Sensitizers Triggers the Maturation of Dendritic Cells

p38 mitogen-activated protein kinase (MAPK) has a crucial role in the maturation of dendritic cells (DCs) by sensitizers. Recently, it has been reported that the oxidation of cell surface thiols by an exogenous impermeant thiol oxidizer can phosphorylate p38 MAPK. In this study, we examined whether sensitizers oxidize cell surface thiols of monocyte-derived DCs (MoDCs). When cell surface thiols were quantified by flow cytometry using Alexa fluor maleimide, all the sensitizers that we examined decreased cell surface thiols on MoDCs. To examine the effects of decreased cell surface thiols by sensitizers on DC maturation, we analyzed the effects of an impermeant thiol oxidizer, o-phenanthroline copper complex (CuPhen). The treatment of MoDCs with CuPhen decreased cell surface thiols, phosphorylated p38 MAPK, and induced MoDC maturation, that is, the augmentation of CD83, CD86, HLA-DR, and IL-8 mRNA, as well as the downregulation of aquaporin-3 mRNA. The augmentation of CD86 was significantly suppressed when MoDCs were pretreated with N-acetyl-L-cystein or treated with SB203580. Finally, we showed that epicutaneous application of 2,4-dinitrochlorobenzene on mouse skin significantly decreased cell surface thiols of Langerhans cells in vivo. These data suggest that the oxidation of cell surface thiols has some role in triggering DC maturation by sensitizers.

Antifibrotic medication using a combination of N-acetyl- L-cystein (NAC) and ACE inhibitors can prevent the recurrence of Dupuytren’s disease

Dupuytren's disease is a progress fibromatosis of unknown origin first described in 1831. Nonoperative treatment options have been suggested involving radiation therapy, vitamin E, local injection therapy suing calcium channel blockers, interferon, corticosteroids or collagenase. Transforming growth factor-beta1 (TGF-beta1) and its downstream Smad signalling system is well established as a key player during fibrogenesis. A number of in vitro experiments have been assessed the blockade of TGF-beta1 and TGF-beta 2. Clinically, a number of antifibrotic agents are available such as N-acetyl-L-cysteins (NAC) as well as angiotensin-converting enzyme (ACE) inhibitors or AT II antagonists. However, to date none of the well known substances has been tested clinically in fibromatosis such as Dupuytren's disease especially to prevent recurrences after surgical release. Antifibrotic medication using a combination of N-acetyl-L-cystein (NAC) and ACE inhibitor can prevent the recurrence of Dupyutren's disease. Given the fact that recurrence rate in Dupuytren's disease is high and unpredictable after surgical release, an antifibrotic intervention might be worthwhile to consider in the clinical setting. Antifibrotic agents inhibit TGF-beta1, which play a key role in fibromatosis. Thus, antifibrotic medication might reduce the recurrence rate in fibromatosis such as Dupuytren's disease in a clinical significant way.

Infrared A-radiation alters the intracellular calciumhomeostasis in human dermal fibroblasts

Infrared-A radiation (IRA; 760–1440 nm), a major component of natural sunlight, accounts for one third of the energy reaching human skin. We have shown in previous studies that IRA irradiation of human dermal fibroblasts (HDF) leads to an increase in expression of matrix metalloproteinase 1 (MMP-1) via an increase in mitochondrial reactive oxygen species (ROS) and subsequent activation of the stress kinases ERK1/2. The aim of this study was to elucidate which retrograde signaling pathways are induced by IRA. Microarray analysis of the IRA response revealed the regulation of several genes related to calcium homeostasis and this together with the known influence of mitochondrial impairment on cellular calcium fluxes prompted us to focus on the effect of IRA on the cellular calcium homeostasis. Our results show for the first time that IRA irradiation (100 J/cm2) of HDF leads to a biphasic increase of the cytosolic calcium level ([Ca2+]c) in the cell. Experiments utilizing EGTA to complex all extracellular calcium confirmed, that the source of the cytosolic calcium increase are intracellular calcium storages. We previously showed that IRA induced MMP-1 expression is dependent on reactive oxygen species (ROS), so we tested whether use of an antioxidant affects the IRA-induced increase of [Ca2+]c. The treatment of HDF with N-acetyl-L-cystein (NAC) mitigates the IRA-induced rise in [Ca2+]c. To address the question of functional relevance of the IRA-induced calcium flux for IRA-induced gene regulation, we treated the cells with the calcium chelator BAPTA-AM. The complexation of intracellular calcium lowers the IRA-induced increase of MMP-1 expression, demonstrating the involvement of calcium in IRA-induced signaling. In conclusion, IRA irradiation leads to a ROS dependent calcium flux from intracellular storages into the cytosol. Interception of the calcium signaling by a calcium chelator affects the IRA induced gene regulation.

Redox regulation in radiation-induced cytochrome c release from mitochondria of human lung carcinoma A549 cells

Mitochondria in mammalian cells are well-known to play an important role in the intrinsic pathway of genotoxic-agent-induced apoptosis by releasing cytochrome c into cytosol and to be a major source of reactive oxygen species (ROS). The aim of this study was to examine whether mitochondrial ROS are involved in radiation-induced apoptotic signaling in A549 cells. Post-irradiation treatment with N-acetyl- l-cystein (NAC) inhibited cytochrome c release from mitochondria but did not affect expression levels of Bcl-2, Bcl-X L and Bax, suggesting that late production of ROS triggered cytochrome c release. Experiments using DCFDA (a classical ROS fluorescence probe) and MitoAR (a novel mitochondrial ROS probe) demonstrated that intracellular and mitochondrial ROS were enhanced 6 h after X irradiation. Furthermore, the O 2 - production ability of mitochondria isolated from A549 cells was evaluated by ESR spectroscopy combined with a spin-trapping reagent (CYPMPO). When isolated mitochondria were incubated with NADH, succinate and CYPMPO, an ESR spectrum due to CYPMPO–OOH was detected. This NADH/succinate-dependent O 2 - production from mitochondria of irradiated cells was significantly increased in comparison with that of unirradiated cells. These results indicate that ionizing radiation enhances O 2 - production from mitochondria to trigger cytochrome c release in A549 cells.

The role of p38 MAPK and JNK in Arsenic trioxide‐induced mitochondrial cell death in human cervical cancer cells

Previously, we have shown that the release of AIF from mitochondria is required for As2O3-induced cell death in human cervical cancer cells, and that reactive oxygen species (ROS) is necessary for AIF release from mitochondria. In this study, we further investigated the role of MAPKs in ROS-mediated mitochondrial apoptotic cell death triggered by As2O3. As2O3-induced apoptotic cell death in HeLa cells was associated with activation and mitochondrial translocation of Bax, a marked phosphorylation of Bcl-2, reduction of Bcl-2 and Bax interaction, dissipation of mitochondrial membrane potential. Using small interfering RNA, reduced Bax expression effectively attenuated As2O3-induced mitochondrial membrane potential loss and apoptotic cell death. Moreover, the phosphorylation of Bcl-2 induced by As2O3 diminished its ability to bind to Bax. Treatment of cells with As2O3 activated both the p38 MAPK and JNK pathways. Mitochondrial translocation of Bax was completely suppressed in the presence of p38 MAPK inhibitor PD169316 or si-p38 MAPK. The As2O3-induced Bcl-2 phosphorylation was attenuated largely by JNK inhibition using SP600125 or si-JNK and to some extent by p38 MAPK inhibition with PD169316 or si-p38 MAPK. In addition, N-acetyl-L-cystein (NAC), a thiol-containing anti-oxidant, completely blocked As2O3-induced p38 MAPK and JNK activations, mitochondria translocation of Bax, and phosphorylation of Bcl-2. These results support a notion that ROS-mediated activations of p38 MAPK and JNK in response to As2O3 treatment signals activation of Bax and phosphorylation of Bcl-2, resulting in mitochondrial apoptotic cell death in human cervical cancer cells.

Nitrogen and Oxygen Molecules in Meningitis-Associated Labyrinthitis and Hearing Impairment

Pneumococcal meningitis remains a serious disease with a case fatality rate of 15%-25%. Furthermore, long-term residues affect up to 50% of survivors. One of the most frequent sequelae is sensorineural hearing loss, which occurs in 26% of survivors of pneumococcal meningitis. Unfortunately, sufficient treatment regimens are still missing. New insights into the pathology and pathophysiology of meningitis-associated hearing loss have come from animal models of bacterial meningitis. Most likely, bacteria reach the cochlea through the cochlear aquaeduct. Once arrived in the perilymphatic spaces, they induce a severe suppurative labyrinthitis. The blood-labyrinth barrier breaks, hair cells are damaged, and neurons in the spiral ganglion undergo cell death, leading to meningitis-associated hearing loss. Reactive oxygen and nitrogen species, in particular peroxynitrite, seem to be among the crucial mediators of cochlear damage and hearing loss during meningitis. In our rat model of pneumococcal meningitis, adjunctive therapy with the antioxidants and peroxynitrite scavengers Mn(III)tetrakis(4-bencoic acid)-porphyrin (MnTBAP) and N-Acetyl-L-Cystein (NAC) significantly attenuated acute and long-term hearing loss. In several other animal studies of pneumococcal meningitis, adjunctive antioxidant therapy also protected infected animals from intracranial complications. Therefore, the use of antioxidants seems to be a promising future treatment option in pneumococcal meningitis.

Reactive oxygen species mediate IAA-lnduced ethylene production in mungbean (Vigna radiata L.) hypocotyls

We reported previously that ROS may function as a downstream component for signaling auxin, a hormone that induces the ethylene production. Here we demonstrated that ROS can act upstream to promote auxin-induced ethylene production in mungbean hypocotyls. When plants were treated with AVG, ethyiene biosynthetic inhibitor, or ACC, ethylene precursor, we found that little effect on the ROS generation. Hypocotyls exposed to H2O2 showed higher ethylene accumulations compared with untreated samples. Furthermore, auxin-induced ethylene production was reduced when tissues were pre-treated with a ROS scavenger, N-acetyl-L-cystein (NAC). We attributed this stimulatory effect to the activation of ethylene biosynthetic enzymes that results from transcriptional up-regulation ofVR- ACS1 andVR- ACS7 to encode ACC synthase, as well as ofVR- ACO1 andVR- ACO2, which encode ACC oxidase.

Aging associated with mild dyslipidemia reveals that COX-2 preserves dilation despite endothelial dysfunction

The endothelial function declines with age, and dyslipidemia (DL) has been shown to hasten this process by favoring the generation of reactive oxygen species (ROS). Cyclooxygenase-2 (COX-2) can be induced by ROS, but its contribution to the regulation of the endothelial function is unknown. Since COX-2 inhibitors may be deleterious to the cardiovascular system, we hypothesized that DL leads to ROS-dependent endothelial damage and a protective upregulation of COX-2. Dilations to acetylcholine (ACh) of renal arteries isolated from 3-, 6-, and 12-mo-old wild-type (WT) and DL mice expressing the human ApoB-100 were recorded with or without COX inhibitors and the antioxidant N-acetyl-l-cystein (NAC). Nitric oxide (NO) and endothelium-derived hyperpolarizing factor (EDHF) were inhibited using N(omega)-nitro-l-arginine (l-NNA) and a depolarizing solution, respectively. In WT mice, the dilation to ACh declined at 12 mo but was insensitive to COX-1/2 inhibition alone or with NAC. DL led to an early endothelial dysfunction at 6 mo, normalized, however, by NAC. At 12 mo, vascular sensitivity to ACh was further reduced by DL. At this age, selective COX-2 inhibition reduced the dilation, whereas addition of NAC improved it. In 3- and 6-mo-old WT mice, l-NNA significantly reduced the dilation, whereas it limited the dilation only in 3-mo-old DL mice. EDHF-dependent dilation remains identical in both groups. These data suggest that COX-2 activity confers endothelium-dependent vasodilatory function in aged DL mice in the face of a pro-oxidative environment. Upregulation of this pathway compensates for the early loss of the contribution of NO in DL mice.

IL-18 enhances the migration ability of murine melanoma cells through the generation of ROI and the MAPK pathway

Interleukin-18 (IL-18) has multiple effects on various cells that are involved in immune escape of murine melanoma cells and in the inflammatory responses. This study investigated the effect of IL-18 on the ability of murine melanoma cells to migrate by using B16F10 cells and the IL-18 antisense transfectants of B16F10 cells (the B16F10/IL-18 antisense transfectant). The B16F10 cells were more able to migrate than were the B16F10/IL-18 antisense transfectants. An exogenous IL-18 treatment improved the ability of the B16F10/IL-18 antisense transfectant cells to migrate, indicating that IL-18 enhanced the migration ability of melanoma cells. To determine the signaling mechanisms involved in IL-18-enhanced migration, we measured the ROI levels. It was found that the ROI levels were increased by IL-18, and an antioxidant, N-acetyl- l-cystein (NAC), blocked the effect of IL-18 on migration, suggesting the involvement of ROI in the signal transduction of IL-18-enhanced cell migration. IL-18-enhanced cell migration was also reduced by PD98059. In addition, the level of ERK1/2 phosphorylation was markedly increased by treating with exogenous IL-18 at 20 min. These results suggest that IL-18 enhances the ability of melanoma cells to migrate via the generation of ROI and the MAPK pathway.