Decrease In Reactive Oxygen Species Formation Research Articles

Does Cell-Type-Specific Silencing of Monoamine Oxidase B Interfere with the Development of Right Ventricle (RV) Hypertrophy or Right Ventricle Failure in Pulmonary Hypertension?

Increased mitochondrial reactive oxygen species (ROS) formation is important for the development of right ventricular (RV) hypertrophy (RVH) and failure (RVF) during pulmonary hypertension (PH). ROS molecules are produced in different compartments within the cell, with mitochondria known to produce the strongest ROS signal. Among ROS-forming mitochondrial proteins, outer-mitochondrial-membrane-located monoamine oxidases (MAOs, type A or B) are capable of degrading neurotransmitters, thereby producing large amounts of ROS. In mice, MAO-B is the dominant isoform, which is present in almost all cell types within the heart. We analyzed the effect of an inducible cardiomyocyte-specific knockout of MAO-B (cmMAO-B KO) for the development of RVH and RVF in mice. Right ventricular hypertrophy was induced by pulmonary artery banding (PAB). RV dimensions and function were measured through echocardiography. ROS production (dihydroethidium staining), protein kinase activity (PamStation device), and systemic hemodynamics (in vivo catheterization) were assessed. A significant decrease in ROS formation was measured in cmMAO-B KO mice during PAB compared to Cre-negative littermates, which was associated with reduced activity of protein kinases involved in hypertrophic growth. In contrast to littermates in which the RV was dilated and hypertrophied following PAB, RV dimensions were unaffected in response to PAB in cmMAO-B KO mice, and no decline in RV systolic function otherwise seen in littermates during PAB was measured in cmMAO-B KO mice. In conclusion, cmMAO-B KO mice are protected against RV dilatation, hypertrophy, and dysfunction following RV pressure overload compared to littermates. These results support the hypothesis that cmMAO-B is a key player in causing RV hypertrophy and failure during PH.

Biosynthesis of copper oxide nanoparticles and its therapeutic efficacy against colon cancer

Abstract In the present study, pumpkin seed extract was used to synthesize copper oxide nanoparticles (CuO NPs) along with evaluating its anticancer activity using different molecular biology tools in the human colorectal cancer cell line (HCT-116). Morphological and structural properties of the biogenically synthesized CuO NPs were characterized by UV-visible spectrophotometry (UV-vis), energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). For estimating the anticancer efficacy, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide cytotoxicity, morphological alteration, reactive oxygen species (ROS) formation, and alterations in the mitochondrial membrane potential (MMP) were determined. SEM and TEM data revealed the formation of spherical nanoparticles possessing an average size of 20 nm. The CuO NPs showed 50% inhibitory concentration (IC50) at 25 µg/mL against the HCT-116 cell line. The treatment with IC50 concentration of CuO NPs showed significant shrinking, detachment, membrane blebbing, and shape distortion of cancer cells. Similarly, the IC50 dose of CuO NPs showed significantly early apoptosis in cancer cells compared to late apoptosis. The cancer cell line also showed a dose-dependent increase and decrease in ROS formation and MMP, respectively. The results obtained through various assays indicated significant anticancer efficacy of biogenically synthesized CuO NPs. Thus, further studies are recommended to validate our results using ex vivo and in vivo models.

NADPH-Oxidase-derived reactive oxygen species are required for cytoskeletal organization, proper localization of E-cadherin and cell motility during zebrafish epiboly

Cell movements are essential for morphogenesis during animal development. Epiboly is the first morphogenetic process in zebrafish in which cells move en masse to thin and spread the deep and enveloping cell layers of the blastoderm over the yolk cell. While epiboly has been shown to be controlled by complex molecular networks, the contribution of reactive oxygen species (ROS) to this process has not previously been studied. Here, we show that ROS are required for epiboly in zebrafish. Visualization of ROS in whole embryos revealed dynamic patterns during epiboly progression. Significantly, inhibition of NADPH oxidase activity leads to a decrease in ROS formation, delays epiboly, alters E-cadherin and cytoskeleton patterns and, by 24 h post-fertilization, decreases embryo survival, effects that are rescued by hydrogen peroxide treatment. Our findings suggest that a delicate ROS balance is required during early development and that disruption of that balance interferes with cell adhesion, leading to defective cell motility and epiboly progression.

Human brain derived cells respond in a type-specific manner after exposure to urban particulate matter (PM)

Exposure to particulate matter (PM), a component of urban air pollution, may cause adverse effects in the brain. Although the exact mechanisms involved are unknown, both oxidative and inflammatory responses have been reported. Since the main route of exposure to particulate matter is through inhalation, there is a potential for compounds to directly enter the brain and alter normal cellular function. Enhancement in both oxidative stress and neuroinflammatory markers has been observed in neurodegenerative disorders and PM-induced potentiation of these events may accelerate the disease process. The objective of this pilot study was to use normal human brain cells, a model system which has not been previously used, to assess cell-type-specific responses after exposure to ultrafine particles (UFP). Human microglia, neurons, and astrocytes were grown separately or as co-cultures and then exposed to aqueous UFP suspensions. Reactive Oxygen Species (ROS) formation and the proinflammatory cytokine tumor necrosis factor alpha (TNF-α) were measured as markers of oxidative stress or inflammation respectively. Our results revealed that after exposure to 2μg/ml of particles, normal human neurons exhibit a decrease in ROS formation and an increase in TNF-α. The observed decrease in ROS formation persisted in the presence of glial cells, which contrasts previous studies done in rodent cells reporting that PM-induced microglial activation modulates neuronal responses. Our study indicates that human CNS cells may respond differently compared to rodent cells and that their use may be more predictive in risk assessment.

The effect of ATP-dependent K(+)-channel opener on transmembrane potassium exchange and reactive oxygen species production upon the opening of mitochondrial pore

The effect of mitochondrial ATP-dependent K(+)-channel (K(+)ATP-channel) opener diazoxide (DZ) on transmembrane potassium exchange and reactive oxygen species (ROS) formation under the opening of mitochondrial permeability transition pore (MPTP) was studied in rat liver mitochondria. The activation of K(+)-cycling (K(+)-uptake and K(+)/H(+)-exchange) by DZ was established with peak effect at < or = 500 nM. It was shown that MPTP opening as well resulted in the activation of K(+)-cycling together with simultaneous activation of Ca(2+)-cycle in mitochondria. In the absence of depolarization Ca(2+)-cycle is supported by MPTP and Ca(2+)-uniporter. The stimulation of K(+)/H(+)-exchange by MPTP opening led to the activation of K(+)-cycle, but further activation of K(+)/H(+)-exchange resulted in MPTP inhibition. Under the same conditions the decrease in mitochondrial ROS production was observed. It was proposed that the decrease in ROS formation together with K(+)/H(+)-exchange activation could be the constituents of the complex effect of MPTP inhibition induced by K(+)ATP-channel opener.

Cooperation of Non-Effective Concentration of Glutamatergic System Modulators and Antioxidant Against Oxidative Stress Induced by Quinolinic Acid

Excessive formation of reactive oxygen species (ROS) and disruption of glutamate uptake have been hypothesized as key mechanisms contributing to quinolinic acid (QA)-induced toxicity. Thus, here we investigate if the use of diphenyl diselenide (PhSe)(2), guanosine (GUO) and MK-801, alone or in combination, could protect rat brain slices from QA-induced toxicity. QA (1mM) increased ROS formation, thiobarbituric acid reactive substances (TBARS) and decreased cell viability after 2h of exposure. (PhSe)(2) (1μM) protected against this ROS formation in the cortex and the striatum and also prevented decreases in cell viability induced by QA. (PhSe)(2) (5μM) prevented ROS formation in the hippocampus. GUO (10 and 100μM) blocked the increase in ROS formation caused by QA and MK-801 (20 and 100μM) abolished the pro-oxidant effect of QA. When the noneffective concentrations were used in combination produced a decrease in ROS formation, mainly (PhSe)(2)+GUO and (PhSe)(2)+GUO+MK-801. These results demonstrate that this combination could be effective to avoid toxic effects caused by high concentrations of QA. Furthermore, the data obtained in the ROS formation and cellular viability assays suggest different pathways in amelioration of QA toxicity present in the neurodegenerative process.

In Vitro Study of Variables Relevant to Perioperative Care of the Surgical Patient: Glucose, Osmolarity, and Rewarming

We sought to determine the effects of altering osmolarity and the reversibility of the detrimental immunologic effects of hypothermia on human monocyte HLA-DR surface expression and reactive oxygen species (ROS) formation. The effects of altering osmolarity on HLA-DR surface expression and ROS formation were assessed using lipopolysaccharide (LPS)-treated samples treated with either saline, glucose, or mannitol, incubated at 37°C for 2 hours. HLA-DR surface receptor expression and ROS formation were determined after incubation. The effects of the reversibility of hypothermia were measured by incubating LPS-treated samples at 34°C, 37°C, and 40°C for 1 hour. The samples were subsequently rewarmed at 40°C for 1 and 2 hours. The effects of rewarming on HLA-DR surface receptor expression and ROS formation were reassessed. In the osmolarity experiments, there was a 49% decrease in ROS formation in samples treated with mannitol as compared with saline and glucose. Alterations of osmolarity had no significant effect on HLA-DR surface expression. In the rewarming experiments, rewarming for either 1 or 2 hours abolished any significant differences in HLA-DR surface expression and ROS formation between samples preincubated at the different temperatures. The presumed inert mannitol was found to significantly decrease ROS formation, but had no effect on HLA-DR surface expression. In addition, the effects of hypothermia on HLA-DR surface expression or ROS formation may be better reversed within 2 hours than in 1 hour.

Cell-density-dependent changes in mitochondrial membrane potential and reactive oxygen species production in human skin cells post sunlight exposure

Solar ultraviolet radiation (UVR) is the principal etiological factor in skin carcinogenesis. In vivo and in vitro studies have demonstrated previously that oxidative DNA damage, mitochondrial mass and mitochondrial membrane potential (MMP) changes are associated with skin cell response to UVR stress. Spontaneously immortalized human skin keratinocytes were irradiated with increasing sub-lethal doses of simulated sunlight irradiation (SSI) using a Q-Sun solar simulator. The effects of SSI on reactive oxygen species (ROS) formation, mitochondrial mass and MMP were then determined. SSI induced mitochondrial mass increase post low SSI (0.25-2.5 J/cm²), whereas higher SSI doses (5.0 and 7.5 J/cm²) decreased mitochondrial mass. Mitochondrial mass increased with time post 5.0 J/cm² irradiation and all changes in mass were independent of cell density status. Changes in ROS and MMP were cell density dependent. Additionally, an inverted dose-dependent decrease in ROS formation was observed 3 h post SSI with the lower SSI dose (0.25 J/cm²). Observations from the present study suggest that changes in the cell's microenvironment (modeled through varying cell density) influence changes in MMP and ROS detoxifying responses in sun-exposed skin cells.

Benidipine, a Long-Acting Calcium Channel Blocker, Inhibits Oxidative Stress in Polymorphonuclear Cells in Patients with Essential Hypertension

To study the relationship between blood pressure and oxidative stress in leukocytes, the effect of benidipine on these variables was compared with that of a placebo. Hypertensive patients were randomly assigned benidipine 4 mg (n=40) or placebo (n=40), and treated for 6 months. Oxidative stress in polymorphonuclear cells (PMNs) was measured by gated flow cytometry. There was a significant relationship between systolic or diastolic arterial pressure and reactive oxygen species (ROS) formation by PMNs in the benidipine group (r=0.61, p<0.01) and in the placebo group (r=0.58, p<0.01). After administration of 4 mg benidipine, ROS formation by PMNs fell by 32 arbitrary units (n=40, p<0.01). After administration of placebo, ROS formation by PMNs decreased by 0.6 arbitrary units (n=40, p=0.31) (p<0.01 for differing treatment effects). There was a significant relationship between the decrease in systolic arterial pressure and the decrease in ROS formation by PMNs in the benidipine group (r=0.52, p<0.01), but not in the placebo group (r=-0.08, p=0.61). There was also a significant relationship between the decrease in diastolic arterial pressure and decrease in ROS formation by PMNs in the benidipine group (r=0.65, p<0.01) but not in the placebo group (r=-0.09, p=0.59). In hypertensive patients, we observed a significant relationship between systolic or diastolic blood pressure and ROS formation by PMNs, and found that benidipine decreased oxidative stress in PMNs of hypertensive patients, at least in part by decreasing blood pressure.