Effect Of H2O2-induced Oxidative Stress Research Articles

70-PUB: Effect of H2O2-Induced Oxidative Stress on Volatile Organic Compounds in Differentiated 3T3-L1 Cells

70-PUB: Effect of H2O2-Induced Oxidative Stress on Volatile Organic Compounds in Differentiated 3T3-L1 Cells

Human gingival mesenchymal stem cells-lyosecretome attenuates adverse effect of hydrogen peroxide-induced oxidative stress on osteoblast cells

ObjectiveTo determine total protein content, antioxidant activity, and protective ability of lyophilized human gingival mesenchymal stem cells (hGMSCs)-secretome in hydrogen peroxide (H2O2) induced oxidative stress model. MethodsHuman GMSCs were cultured to obtain a conditioned medium (secretome), then lyophilized to produce lyosecretome. Total protein was determined by bicinchoninic acid assay (BCA) and SDS-PAGE to improve protein measurements. Antioxidant concentration was measured by ABTS assay, while the protective ability of lyosecretome against oxidative stress was determined by the metabolic activity of osteoblast cells. The study group was divided into a control group (culture medium) and a lyosecretome treatment group (0.0; 0.157, 0.313, 0.625, 1.25, 2.5, 5, and 10 mg/mL + H2O2). ResultsLyosecretome had a protein concentration of 2086.00 ± 0.20 μg/ml, with a molecular weight of 174, 74, 61, 55, and 26 kDa, which are thought to facilitate cell migration, as well as bind cytokines and growth factors. Lyosecretome also provided the highest antioxidant activity of 93.51% at a concentration of 4.8 mg/ml, with an IC50 value of 2.08 mg/ml. The highest cell metabolic activity (79.53 ± 2.41%) was shown in the 1.25 mg/ml lyosecretome treatment group. All concentrations of hGMSC-lyosecretome attenuate the adverse effect of H2O2-induced oxidative stress. ConclusionLyosecretome obtained from hGMSCs can maintain metabolic activity in osteoblast cells as protection against H2O2 oxidative stress.

The palm oil-based chlorophyll removal and the evaluation of antiaging properties on Centella asiatica ethanolic extract

Centella asiatica is an essential medicinal herb in numerous traditions. The high chlorophyll concentration of C. asiatica makes dosage form formulation challenging. On the other hand, palm oil is feasible to eliminate the chlorophyll from plant-based products. This research aim to analysis the phytochemical profile and in vitro anti-aging effects on chlorophyll removal of C. asiatica extract. The extract was soxhletated in 70% ethanol. The extract was partitioned with 50% ethanol and palm oil to create a dechlorophyllation extract. Asiaticoside was analyzed using TLC-densitometry. The cytoprotective effect of H2O2-induced oxidative stress in Vero cells was assessed using MTT assays. Flow cytometer analysis was used for quantifying the intracellular ROS. The senescence-associated-β-galactosidase assay was used to identify senescent cells. The efficiency of chlorophyll removal by palm oil was 90.94±0.62%. The dechlorophyllation extract (DE) showed a concentration of 1.58±0.02% for asiaticoside, but it was not found in the original extract (OE). DE significantly reduced H2O2-induced cytotoxicity in Vero cells compared to OE. Both DE and OE reduced intracellular ROS and senescent cells. Palm oil-based chlorophyll removal improved the phytochemical content and anti-aging effects of C. asiatica in ethanolic extract.

Can atypical response in endothelial dysfunction-related genes and microRNAs arise from low hydrogen peroxide exposure?

Vascular endothelium is a tissue in which several vasoactive substances are produced and secreted. Reactive oxygen species can cause endothelial dysfunction (ED). miRNAs can be implicated in the oxidative stress-related ED during vascular disease pathogeneses. Our aim is to investigate effect of H2O2-induced oxidative stress on expression levels of genes and miRNAs that are key players in ED. H2O2 effect on cell viability of human umbilical-vein endothelial cells (HUVEC) at 24-hour was measured with MTT. Low sub-cytotoxic H2O2 concentrations (25, 50µM) were selected to analyze their oxidative stress-inducing capacities with MDA assay and their effects on EDN1, NOS3, VCAM1, SERPINE1, miR21, miR22, miR126, and miR146a levels with RT-qPCR. Each tested H2O2 concentration reduced HUVEC cell viability. Fifty µM H2O2 augmented cellular MDA levels. Intriguingly, EDN1, VCAM1, and SERPINE1 and all analyzed miRNAs' levels attenuated upon H2O2 treatment whereas there was no change in NOS3 levels compared to control. There was a positive correlation between miR-21 and VCAM1. Rather than individual alterations in analyzed parameters, consistent changes in our findings i.e., parallel decreases in EDN1, VCAM1, SERPINE1 mRNA levels as well as miRNAs, suggests that H2O2 concentration-dependent modulation of expression patterns can bring about various impacts on ED (Tab. 1, Fig. 5, Ref. 63).

EFFECTS OF CASTRATION AND SEX HORMONES ON ANTIOXIDANT STATUS AND SOME BIOCHEMICAL PARAMETERS OF MALE RABBITS EXPOSED TO OXIDATIVE STRESS

The present study was aimed to investigate the effect of estrogen and testosterone as antioxidants and their ability to prevent the effect of H2O2-induced oxidative stress and their reflections on blood parameters and antioxidant status of male rabbits. 72 adult male rabbits were divided randomly into 12 groups (6/group), 1st group: Intact, 2nd group: Intact-H2O2, 3rd group: Castrated, 4th group: Castrated-H2O2, 5th group: Intact-H2O2-Testosterone, 6th group: Castrated-H2O2-Testoterone, 7th group: Intact-H2O2-Estrogen, 8th group: Castrated-H2O2-Estrogen, 9th group: Intact-Testosterone, 10th group: Castrated-Testosterone, 11th group: Intact-Estrogen, 12th group: Castrated-Estrogen, treatments continued for 4 weeks. Results showed that castration increased significantly GSH, TAC, TG, HDL-C levels, and significantly decreased MDA, AST, ALT levels. Treatment with H2O2 caused a significant decrease in the levels of GSH, TAC, HDL-C, total proteins, and a significant increase in the levels of MDA, cholesterol, TG, LDL-C, ALT, AST compared to untreated group. On the other hand, estrogen treatment improves TAC, GSH and lipid profile and reduce MDA significantly as compared with testosterone treatment and control group. In regard to interaction effects, castration without H2O2- estrogen treatment reduces the stress as represented by the reduction of MDA, risk index, ALT and elevate the GSH and TAC levels. These results indicate that castration and estrogen treatment of castrated and intact male rabbits reduce stress effects and improve the lipid profile and some immunological measures.

Dysregulation of X-ray repair cross-complementing 4 expression in the eutopic endometrium of women with endometriosis.

Recent data suggest that the DNA damage response (DDR) is altered in the eutopic endometrium (EE) of women with endometriosis and this probably ensues in response to higher DNA damage encountered by the EE in endometriosis. DDR operates in a tissue-specific manner and involves different pathways depending on the type of DNA lesions. Among these pathways, the non-homologous end joining (NHEJ) pathway plays a critical role in the repair of dsDNA breaks. The present study was undertaken to explore whether NHEJ is affected in the EE of women with endometriosis. Toward this, we focused on the X-ray repair cross-complementing 4 (XRCC4) protein, one of the core components of the NHEJ pathway. Endometrial XRCC4 protein levels in the mid-proliferative phase were found significantly (P < 0.05) downregulated in women with endometriosis, compared to control women. Investigation of a microarray-based largest dataset in the Gene Expression Omnibus database (GSE51981) revealed a similar trend at the transcript level in the EE of women with endometriosis, compared to control women. Further in vitro studies were undertaken to explore the effects of H2O2-induced oxidative stress on DNA damage, as assessed by γ-H2AX and 8-hydroxy-2'-deoxyguanosine (8-OHdG) immunolocalization, and XRCC4 protein levels in endometrial stromal (hTERT immortalized human endometrial stromal cell line (ThESCs)) and epithelial (Ishikawa) cells. A significant decrease in XRCC4 protein levels and significantly higher localization of γ-H2AX and 8-OHdG were evident in ThESCs and Ishikawa cells experiencing oxidative stress. Overall, the study demonstrates that the endometrial XRCC4 expression is dysregulated in women with endometriosis and this could be due to higher oxidative stress in endometriosis.

Influence of H2O2-Induced Oxidative Stress on In Vitro Growth and Moniliformin and Fumonisins Accumulation by Fusarium proliferatum and Fusarium subglutinans.

Fusarium proliferatum and Fusarium subglutinans are common pathogens of maize which are known to produce mycotoxins, including moniliformin (MON) and fumonisins (FBs). Fungal secondary metabolism and response to oxidative stress are interlaced, where hydrogen peroxide (H2O2) plays a pivotal role in the modulation of mycotoxin production. The objective of this study is to examine the effect of H2O2-induced oxidative stress on fungal growth, as well as MON and FBs production, in different isolates of these fungi. When these isolates were cultured in the presence of 1, 2, 5, and 10 mM H2O2, the fungal biomass of F. subglutinans isolates showed a strong sensitivity to increasing oxidative conditions (27–58% reduction), whereas F. proliferatum isolates were not affected or even slightly improved (45% increase). H2O2 treatment at the lower concentration of 1 mM caused an almost total disappearance of MON and a strong reduction of FBs content in the two fungal species and isolates tested. The catalase activity, surveyed due to its crucial role as an H2O2 scavenger, showed no significant changes at 1 mM H2O2 treatment, thus indicating a lack of correlation with MON and FB changes. H2O2 treatment was also able to reduce MON and FB content in certified maize material, and the same behavior was observed in the presence and absence of these fungi, highlighting a direct effect of H2O2 on the stability of these mycotoxins. Taken together, these data provide insights into the role of H2O2 which, when increased under stress conditions, could affect the vegetative response and mycotoxin production (and degradation) of these fungi.

Nrf2 drives oxidative stress-induced autophagy in nucleus pulposus cells via a Keap1/Nrf2/p62 feedback loop to protect intervertebral disc from degeneration

Intervertebral disc (IVD) degeneration is known to aggravate with age and oxidative stress is implicated in the pathogenesis of many age-related diseases. Nuclear factor (erythroid-derived-2)-like 2 (Nrf2) can confer adaptive protection against oxidative and proteotoxic stress in cells. In this study, we assessed whether Nrf2 can protect against oxidative stress in nucleus pulposus (NP) cells. In addition, we investigated Nrf2 expression in NP tissue samples from patients with different degrees of IVD degeneration and a mouse model of aging and IVD degeneration and the influence of H2O2-induced oxidative stress on autophagic pathways in NP cells. Autophagy was assessed by measuring levels of autophagy-related protein (ATG) family members and the autophagic markers, p62 and LC3. We found that expression of Nrf2 progressively decreased in human NP tissue samples of patients with increasing degrees of IVD degeneration. Nrf2 deficiency leads to the degeneration of IVDs during aging. Nrf2 knockout also aggravates IVD degeneration and reduces autophagic gene expression in an induced mouse model of IVD degeneration. The detrimental effects of H2O2-induced oxidative stress were increased in autophagy-deficient cells via reduced expression of Atg7 and the Keap1–Nrf2–p62 autophagy pathway. Taken together, these results suggest that excessive oxidative stress causes the upregulation of autophagy, and autophagy acts as an antioxidant feedback response activated by a Keap1-Nrf2-p62 feedback loop in IVD degeneration.

Hydrogen peroxide-induced oxidative stress upregulates ght5 gene belonging to hexose transporters in Schizosaccharomyces pombe

Hydrogen peroxide is an agent that triggers oxidative stress. Glucose, which is a source of carbon and energy has a regulatory role in many metabolic processes such as growth rate, fermentation capacity and stress response. Schizosaccharomyces pombe has eight hexose transporters with a different affinity for glucose and/or related monosaccharides. In S. pombe, Ght5 is a glucose transporter with high-affinity. We aimed to investigate the effects of H2O2-induced oxidative stress on hexose transporters using glucose repression-resistant mutant strains (ird5 and ird11) of S. pombe. We analyzed the percentage of glucose consumption in S. pombe wild-type and mutant cells under stressed and non-stressed conditions. Then we compared the expression levels of the genes encoding hexose transporters under the same conditions. We confirmed that the glucose consumption efficiencies of the mutants were slower than the wild-type as in earlier study under non-stressed condition. The percentage of glucose consumption reduced by approximately two-fold in ird11 and wild-type, but not change in ird5, under a stressed condition. There is no difference between cells shape and size of S. pombe strains under stressed and non-stressed conditions. Under stress-induced condition, the expression levels of ght3, ght4 genes in ird11 and wild-type, and ght4, ght6 genes in ird5 decreased, but that of ght5 gene remarkably increased in only wild-type. We suggested that oxidative stress caused by H2O2 leads to upregulation of the ght5 gene in S. pombe.

Involvement of NADPH Oxidase 1 in Liver Kinase B1-Mediated Effects on Tumor Angiogenesis and Growth.

The liver kinase B1 (LKB1) gene is a tumor suppressor with an established role in the control of cell metabolism and oxidative stress. However, whether dis-regulated oxidative stress promotes growth of LKB1-deficient tumors remains substantially unknown. Through in vitro studies, we observed that loss of LKB1 perturbed expression of several genes involved in reactive oxygen species (ROS) homeostasis. In particular, this analysis evidenced strongly up-modulated NADPH oxidase 1 (NOX1) transcript levels in tumor cells lacking LKB1. NOX1 accounted in part for enhanced cytotoxic effects of H2O2-induced oxidative stress in A549 LKB1-deficient tumor cells. Notably, genetic and pharmacologic inhibition of NOX1 activity reduced angiogenesis and growth of A549 tumors in mice. These results suggest that NOX1 inhibitors could counteract ROS production and the angiogenic switch in LKB1-deficient tumors.

Effects of flavonoids from Gynostemma pentaphyllum on A549 cells damaged by hydrogen peroxide

This study focuses on the therapeutical effect of flavonoids from Gynostemma pentaphyllum on human lung carcinoma A549 cells induced by H₂O₂ oxidative stress and its possible mechanisms. The oxidative damage model was established using different concentrations H₂O₂ to induce A549 cell for different hours, and then treated with the flavonoids for 10 hours. The effects of flavonoids from G. pentaphyllum on cell viability of A549 cell damaged by H₂O₂ were detected by MTT assay. The contents of ROS were detected by DCFH-DA fluorescent probe method via flow cytometer. The contents of MDA, SOD and GSH were detected by TBA，NBT and DTNB-linked colorimetry assay, respectively. Expressions levels of Nrf2, NQO1 and HO-1 in A549 cells were evaluated by Western blot. The results showed that the cell activity was decreasing with the rise of H₂O₂ concentration within the range of 200-700 μmol·L⁻¹. The cell viability was 60.4% after treated with 500 μmol·L⁻¹H₂O₂ for 10 h, so it was chosen to be as an oxidant stress model. Compared with normal group，the contents of SOD, GSH and HO-1 expressions were lower after damaged with H₂O₂. On the contrary, the contents of ROS and MDA expressions were increased. Compared with model group, the contents of SOD, GSH and the expressions of Nrf2, NQO1 and HO-1 were increased after treated with flavonoids from G. pentaphyllum. The above results demonstrate that flavonoids from G. pentaphyllum may attenuate the effect of H₂O₂-induced oxidative stress on A549 cell by resisting oxidation. The finding may provide a biological evidence for the application of the G. pentaphyllum to fight the oxidative stress related diseases.

Hydrogen Peroxide Prolongs Mitotic Arrest in a Dose Dependent Manner and Independently of the Spindle Assembly Checkpoint Activity in Saccharomyces cerevisiae

Oxidative stress and chromosome missegregation are important factors that are linked to aneuploidy. A major reason for chromosome missegragation is the inappropriate activity of the spindle assembly checkpoint (SAC), a conserved surveillance mechanism that monitors the state of kinetochore-microtubule attachments to ensure equal chromosome segregation in mitosis. SAC-activation induces a prolonged mitotic arrest. Mitosis is considered the most vulnerable cell cycle phase to several external signals, therefore increasing the time cells spent in this phase via mitotic arrest induction by SAC-activating agents is favorable for cancer therapy. Cancer cells also display elevated oxidative stress due to abnormally high production of reactive oxygen species (ROS). However, the effect of increased oxidative stress on the duration of mitotic arrest remains largely unknown. In this study, we investigated the effect of H2O2-induced oxidative stress on the mitotic arrest induced by a SAC-activating agent (nocodazole) in Saccharomyces cerevisiae. Our data suggest that oxidative stress prolongs SAC-activation induced mitotic arrest in a dose dependent manner. We, in addition, investigated the effect of H2O2 treatment on the mitotic arrest induced independently of SAC-activation by using a conditional mutant (cdc23) and showed that the effect of H2O2-induced oxidative stress on mitotic arrest is independent of the SAC activity.

The role of Golgi reassembly and stacking protein 65 phosphorylation in H2O2-induced cell death and Golgi morphological changes

This study aimed to investigate the effects of H2O2-induced oxidative stress on cell viability and survival, as well as changes in the distribution of Golgi apparatus and in the level of Golgi reassembly and stacking protein 65 (GRASP65). Cell viability of cultured N2a cells treated with H2O2 was measured by the MTT assay. Apoptosis was measured by flow cytometry analyses. Cells labeled by indirect immunofluorescence were observed under confocal microscope to detect any Golgi morphological alterations; electron microscopy of Golgi apparatus was also done. Expression of GRASP65 and phospho-GRASP65 was examined by immunoblotting. H2O2 treatment reduced the cell viability and raised the cell mortality of N2a cells in a time-dependent manner. Notable changes were only observed in the distribution and morphology of Golgi apparatus at 6h after H2O2 treatment. The expression of GRASP65 showed no significant changes at different time points; the phosphorylated GRASP65 level was significantly increased after H2O2 treatment, peaked at 3h, and finally dropped at 6h. Taken together, GRASP65 phosphorylation may have a critical role in inducing cell death at the early stage after H2O2 treatment, while its role in H2O2-induced Golgi morphological changes may be complex.

H2O2-Induced Oxidative Stress Affects SO4= Transport in Human Erythrocytes.

The aim of the present investigation was to verify the effect of H2O2-induced oxidative stress on SO4= uptake through Band 3 protein, responsible for Cl-/HCO3- as well as for cell membrane deformability, due to its cross link with cytoskeletal proteins. The role of cytoplasmic proteins binding to Band 3 protein has been also considered by assaying H2O2 effects on hemoglobin-free resealed ghosts of erythrocytes. Oxidative conditions were induced by 30 min exposure of human erythrocytes to different H2O2 concentrations (10 to 300 μM), with or without GSH (glutathione, 2 mM) or curcumin (10 μM), compounds with proved antioxidant properties. Since SO4= influx through Band 3 protein is slower and better controllable than Cl- or HCO3- exchange, the rate constant for SO4= uptake was measured to prove anion transport efficiency, while MDA (malondialdehyde) levels and –SH groups were estimated to quantify the effect of oxidative stress. H2O2 induced a significant decrease in rate constant for SO4= uptake at both 100 and 300 μM H2O2. This reduction, observed in erythrocytes but not in resealed ghosts and associated to increase in neither MDA levels nor in –SH groups, was impaired by both curcumin and GSH, whereas only curcumin effectively restored H2O2-induced changes in erythrocytes shape. Our results show that: i) 30 min exposure to 300 μM H2O2 reduced SO4= uptake in human erythrocytes; ii) oxidative damage was revealed by the reduction in rate constant for SO4= uptake, but not by MDA or –SH groups levels; iii) the damage was produced via cytoplasmic components which cross link with Band 3 protein; iv) the natural antioxidant curcumin may be useful in protecting erythrocytes from oxidative injury; v) SO4= uptake through Band 3 protein may be reasonably suggested as a tool to monitor erythrocytes function under oxidative conditions possibly deriving from alcohol consumption, use of drugs, radiographic contrast media administration, hyperglicemia or neurodegenerative diseases.

Effect of H2O2-Induced Oxidative Stress on Sclerotial Differentiation and Asa-GSH Cycle of Penicillium thomii Q1 Strain

Penicillium thomii Q1 strain was able to form abundant orange, sand-shaped sclerotia in which carotenoids were accumulated. The aim of this work was to determine the effects of H2O2-induced oxidative stress on the sclerotial differentiation and ascorbate-glutathione (AsA-GSH) cycle of Q1 strain. Results showed that the oxidative stress induced by H2O2 was clearly dependent on the H2O2 concentrations in media. The higher the concentration of H2O2 was, the higher the sclerotial biomass and carotenoids content in sclerotia (Rbiomass=0.972, Rcontent=0.941) (P<0.05). H2O2- induced oxidative stress favored the sclerotial differentiation. Results indicated that H2O2-induced oxidative stress can improve the contents of reduced form of ascorbate (ASC) and dehydroascorbate (DHA) and the ratio of ASC/DHA in sclerotia of Penicillium thomii Q1 strain (RASC=0.727, RDHA=0.640, RASC/DHA=0.929). The contents of DHA and ASC were increased by 1.9-fold and 2.4-fold with respect to control. At the same oxidative stress condition, DHA content was higher than ASC content. Oxidative stress may increase the contents of reduced glutathione (GSH) and oxidized glutathione (GSSG) in sclerotia of Penicillium thomii Q1 strain (RGSH=0.888, RGSSG=0.997). The value of the ratio of GSH/GSSG had a negative correlation with the oxidative stress (R=-0.933). At the same oxidative stress condition, GSH content was higher than GSSG content. The values of Ascorbate peroxidase (APX) and Glutathione reductase (GR) activities had negative correlation with the oxidative stress (R APX=-0.555) (RGR=-0.420). The values of Monodehydroascorbate reductase (MDHAR) and Dehydroascorbate reductase (DHAR) activities had positive correlation with the oxidative stress (RMDHAR=0.448) (R DHAR=0.603).

Mitochondrial Apoptotic Pathway Is Activated by H2O2-Mediated Oxidative Stress in BmN-SWU1 Cells from Bombyx mori Ovary.

Apoptosis is a known regulator of morphogenetic events. In mammals, the critical role of oxidative stress-induced apoptosis has been well-studied; however, in insects the role of oxidative stress in apoptosis is not clear. In a previous study, we showed that apoptosis-related genes are present in the silkworm Bombyx mori, an important lepidopteran insect model. In this study, we evaluated the effect of H2O2-induced oxidative stress on apoptosis, reactive oxygen species (ROS) levels, mitochondrial response, cytochrome c release and apoptosis-related gene expression in the BmN-SWU1 cell line from B. mori ovaries. Our results showed that BmN-SWU1 cells exposed to H2O2 showed cell protuberances, cytoplasmic condensation, apoptotic bodies, DNA ladder formation and caspase activities indicating apoptosis. H2O2-induced apoptosis also increased intracellular ROS level, changed mitochondrial distribution, reduced mitochondrial membrane potential and increased the release of cytochrome c from mitochondria. Furthermore, western blot analysis revealed a significant increase in p53 and cytochrome c expression, and a decrease in Bcl-2 expression compared to the controls. Moreover, quantitative real-time PCR (qRT-PCR) showed an increase in the transcript levels of BmICE, Bmapaf-1 and BmEndoG by 439.5%, 423.9% and 42.2%, respectively, after treatment with 1 μM H2O2 for 24 h. However, the transcript levels of Bmbuffy declined by 41.4% after 24 h of exposure to 1 μM H2O2. These results show that H2O2 treatment induced apoptosis in BmN-SWU1 cells via the mitochondrial apoptotic pathway. Further, it appears that oxidative stress induced by H2O2 activates both caspase-dependent and caspase-independent mitochondrial apoptotic pathways in silkworm cells. Taken together, these findings improve our knowledge of apoptosis in silkworm and the apoptotic pathways in insects.

Mechanism of H2O2-induced oxidative stress regulating viability and biocontrol ability of Rhodotorula glutinis

The use of antagonistic yeasts to control postharvest pathogens is a promising alternative to fungicides. The effectiveness of the antagonists against fungal pathogens is greatly dependent on their viability, which is usually mediated by reactive oxygen species (ROS). Here, we investigated the effects of H2O2-induced oxidative stress on the viability and biocontrol efficacy of Rhodotorula glutinis and, using flow cytometric analysis, observed the changes of ROS accumulation and apoptosis in the yeast cells with or without H2O2 treatment. We found that the viability of R. glutinis decreased in a time- and dose-dependent manner under H2O2-induced oxidative stress. Compared to the control, yeast cells exposed to oxidative stress exhibited more accumulation of ROS and higher levels of protein oxidative damage, but showed lower efficacy for biocontrol of Penicillium expansum causing blue mold rot on peach fruit. The results indicate that apoptosis is a main cause of the cell viability loss in R. glutinis, which is attributed to ROS accumulation under oxidative stress. These findings offer a plausible explanation that oxidative stress affects biocontrol efficacy of R. glutinis via regulating its viability and cell apoptosis.

Enhanced gellan gum production by hydrogen peroxide (H2O2) induced oxidative stresses in Sphingomonas paucimobilis

In this study, the effect of H2O2-induced oxidative stress on gellan gum production and cell growth were investigated. Gellan gum production was improved and cell growth was inhibited by H2O2. A multiple H2O2 stresses with different concentrations were developed to optimize gellan gum production. A maximal gellan gum yield (22.52g/L), which was 35.58% higher than the control, was observed with 2, 2, 3, 4mmol/L H2O2 added at 6, 12, 18, 24h, respectively. Moreover, UDP-glucose pyrophosphorylase activity and glucosyltransferase activity were increased with H2O2 stresses. This new strategy of multiple H2O2-induced oxidative stresses would be further applied to gellan gum production in future study.

Exogenous proline alleviates the effects of H2O2-induced oxidative stress in wild almond species

The effect of proline on the antioxidant system in the leaves of eight species of wild almond (Prunus spp.) exposed to H2O2-mediated oxidative stress was studied. The levels of endogenous proline (Pro) and hydrogen peroxide, and the activities of total superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), glutathione reductase (GR), and guaiacol peroxidase (POD) were measured. The degradation of chlorophyll but not carotenoids occurred in leaves in the solution of 5 mM H2O2. An increase in membrane lipid peroxidation was observed in H2O2 treatment, as assessed by MDA level and percentage of membrane electrolyte leakage (EL). Significant increases in total SOD and CAT activities, as well as decreases in APX and POD activities, were detected in H2O2-treated leaves. The three SOD isoforms showed different behavior, as Mn-SOD activity was enhanced by H2O2, whereas Fe-SOD and Cu/Zn-SOD activities were inhibited. In addition, Pro accumulation up to 0.1 μmol/g fr wt, accompanied by significant decreases in ascorbate and glutathione levels, was observed in H2O2-treated leaves. After two different treatments with 10 mM Pro + 5 mM H2O2, total SOD and CAT activities were similar to the levels in control plants, while POD and APX activities were higher if compared to the leaves exposed only to H2O2. Pro + H2O2 treatments also caused a strong reduction in the cellular H2O2 and MDA contents and EL. The results showed that Pro could have a key role in protecting against oxidative stress injury of wild almond species by decreasing membrane oxidative damage.

118 ONOBOTULINUMTOXIN A AMELIORATES OXIDATIVE STRESS-INDUCED DETRUSOR OVERACTIVITY

You have accessJournal of UrologyUrodynamics/Incontinence/Female Urology: Basic Research II1 Apr 2012118 ONOBOTULINUMTOXIN A AMELIORATES OXIDATIVE STRESS-INDUCED DETRUSOR OVERACTIVITY Alex Lin, C.C. Lin, Y.Z. Shu, and K.K. Chen Alex LinAlex Lin Taipei, Taiwan More articles by this author , C.C. LinC.C. Lin Taipei, Taiwan More articles by this author , Y.Z. ShuY.Z. Shu Taipei, Taiwan More articles by this author , and K.K. ChenK.K. Chen Taipei, Taiwan More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2012.02.166AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES We investigated the effect of onobotulinumtoxin A on the detrusor overactivity resulting from H2O2-induced oxidative stress. METHODS The urinary bladders of male New Zealand rabbit were treated with intravesical protamine sulfate followed by instillation of either 50 units onobotulinumtoxin A (BTX-H2O2 group, n=6) or normal saline (NS- H2O2 group, n=6) for one hour. One week later continuous cystometry with 1% hydrogen peroxide (H2O2) or normal saline (NS-NS, n=6) was performed for one hour. Contractile responses to 120mM KCl, field stimulation and bethanechol were then tested on bladder strips with (Uro+) and without (Uro−) urothelial layer in organ bath. Separate groups of animals received subcutaneous capsaicin (n=3) 4 days before or intravenous indomethacin (n=3) during intravesical H2O2 infusion. Expression of nitrotyrosine was determined with immunohistochemistry. RESULTS Comparing with NS-NS group, intravesical H2O2(NS-H2O2) induced detrusor overactivity with a significant reduction in the cystometric bladder capacity and inter-contraction interval. Prior treatment with intravesical onobotulinumtoxin A abolished the stimulatory effects of H2O2. Pre-treatment with subcutaneous capsaicin or intravenous indomethacin during H2O2 infusion also abolished the stimulation of H2O2 on bladder activity. The contractile response of detrusor strips of NS- H2O2 group to KCl, field stimulation and bethanechol was significantly higher than that of strips obtained from NS-NS group. But the contractile response of strips obtained from BTX-H2O2 was similar to those of strips from NS-NS. The contractile response of Uro- strips was significantly greater than those of Uro+ strips in both NS-NS and BTX-H2O2 groups. However, in NS-H2O2 group the contractile response was not different between Uro+ and Uro- strips. Expression of nitrotyrosine was increased following H2O2 infusion, but there was no difference between BTX-H2O2 and NS-H2O2 groups. CONCLUSIONS H2O2-induced oxidative stress results in enhanced detrusor contractility and a loss of urothelial inhibitory activity on detrusor contraction. Capsaicin pre-treatment, intravenous indomethacin and pre-treatment with intravesical onobotulinumtoxin A ameliorate the stimulatory effect of H2O2 on bladder activity. We postulate that stimulatory effect of H2O2-induced oxidative stress on the bladder might be secondary to the enhanced prostaglandin synthesis mediating via c-fiber activation, which could be inhibited by onobotulinumtoxin A. © 2012 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 187Issue 4SApril 2012Page: e48 Advertisement Copyright & Permissions© 2012 by American Urological Association Education and Research, Inc.MetricsAuthor Information Alex Lin Taipei, Taiwan More articles by this author C.C. Lin Taipei, Taiwan More articles by this author Y.Z. Shu Taipei, Taiwan More articles by this author K.K. Chen Taipei, Taiwan More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...