Impulsive noise removal from color images with morphological filtering

This paper deals with impulse noise removal from color images. The proposed noise removal algorithm employs a novel approach with morphological filtering for color image denoising; that is, detection of corrupted pixels and removal of the detected noise by means of morphological filtering. With the help of computer simulation we show that the proposed algorithm can effectively remove impulse noise. The performance of the proposed algorithm is compared in terms of image restoration metrics and processing speed with that of common successful algorithms.Comment: The 6th international conference on analysis of images, social networks, and texts (AIST 2017), 27-29 July, 2017, Moscow, Russi

Heme oxygenase-1 derived carbon monoxide suppresses Aβ1-42 toxicity in astrocytes

Neurodegeneration in Alzheimer’s disease (AD) is extensively studied, and the involvement of astrocytes and other cell types in this process has been described. However, the responses of astrocytes themselves to amyloid β peptides ((Aβ; the widely accepted major toxic factor in AD) is less well understood. Here, we show that Aβ(1-42) is toxic to primary cultures of astrocytes. Toxicity does not involve disruption of astrocyte Ca2+ homeostasis, but instead occurs via formation of the toxic reactive species, peroxynitrite. Thus, Aβ(1-42) raises peroxynitrite levels in astrocytes, and Aβ(1-42) toxicity can be inhibited by antioxidants, or by inhibition of nitric oxide (NO) formation (reactive oxygen species (ROS) and NO combine to form peroxynitrite), or by a scavenger of peroxynitrite. Increased ROS levels observed following Aβ(1-42) application were derived from NADPH oxidase. Induction of heme oxygenase-1 (HO-1) protected astrocytes from Aβ(1-42) toxicity, and this protective effect was mimicked by application of the carbon monoxide (CO) releasing molecule CORM-2, suggesting HO-1 protection was attributable to its formation of CO. CO suppressed the rise of NADPH oxidase-derived ROS caused by Aβ(1-42). Under hypoxic conditions (0.5% O2, 48h) HO-1 was induced in astrocytes and Aβ(1-42) toxicity was significantly reduced, an effect which was reversed by the specific HO-1 inhibitor, QC-15. Our data suggest that Aβ(1-42) is toxic to astrocytes, but that induction of HO-1 affords protection against this toxicity due to formation of CO. HO-1 induction, or CO donors, would appear to present attractive possible approaches to provide protection of both neuronal and non-neuronal cell types from the degenerative effects of AD in the central nervous system

Heme oxygenase-1 derived carbon monoxide suppresses Aβ1-42 toxicity in astrocytes

Neurodegeneration in Alzheimer’s disease (AD) is extensively studied, and the involvement of astrocytes and other cell types in this process has been described. However, the responses of astrocytes themselves to amyloid peptides ((A; the widely accepted major toxic factor in AD) is less well understood. Here, we show that A(1-42) is toxic to primary cultures of astrocytes. Toxicity does not involve disruption of astrocyte Ca2+ homeostasis, but instead occurs via formation of the toxic reactive species, peroxynitrite. Thus, A(1-42) raises peroxynitrite levels in astrocytes, and A(1-42) toxicity can be inhibited by antioxidants, or by inhibition of nitric oxide (NO) formation (reactive oxygen species (ROS) and NO combine to form peroxynitrite), or by a scavenger of peroxynitrite. Increased ROS levels observed following A(1-42) application were derived from NADPH oxidase. Induction of heme oxygenase-1 (HO-1) protected astrocytes from A(1-42) toxicity, and this protective effect was mimicked by application of the carbon monoxide (CO) releasing molecule CORM-2, suggesting HO-1 protection was attributable to its formation of CO. CO suppressed the rise of NADPH oxidase-derived ROS caused by A(1-42). Under hypoxic conditions (0.5% O2, 48h) HO-1 was induced in astrocytes and A(1-42) toxicity was significantly reduced, an effect which was reversed by the specific HO-1 inhibitor, QC-15. Our data suggest that A(1-42) is toxic to astrocytes, but that induction of HO-1 affords protection against this toxicity due to formation of CO. HO-1 induction, or CO donors, would appear to present attractive possible approaches to provide protection of both neuronal and non-neuronal cell types from the degenerative effects of AD in the central nervous system

Effect of native and oxidized low-density lipoprotein on endothelial nitric oxide and superoxide production : key role of L-arginine availability.

Abstract BACKGROUND: Native and oxidized LDLs (n-LDL and ox-LDL) are involved in the atherogenic process and affect endothelium-dependent vascular tone through their interaction with nitric oxide (NO). METHODS AND RESULTS: In this study we evaluated directly, by using a porphyrinic microsensor, the effect of increasing lipoprotein concentrations on endothelial NO and superoxide (O(2)(-)) production. We investigated where lipoproteins may affect the L-arginine-NO pathway by pretreating cells with L-arginine, L-N-arginine methyl ester (L-NAME), and superoxide dismutase. Bovine aortic endothelial cells were exposed for 1 hour to increasing concentrations of n-LDL (from 0 to 240 mg cholesterol/dL) and ox-LDL (from 0 to 140 mg cholesterol/dL). A stimulated (calcium ionophore) NO concentration decreased to 29% of the control at n-LDL concentration of 80 mg cholesterol/dL and to 15% of the control at 20 mg cholesterol/dL of ox-LDL. L-Arginine partially neutralized the inhibitory effect of n-LDL and ox-LDL on the NO generation. Superoxide dismutase pretreatment did not modify NO production, whereas L-NAME blunted NO generation at all LDL concentrations. O(2)(-) production was increased at low n-LDL and very low ox-LDL concentrations; this was reversed by L-arginine. CONCLUSIONS: These findings confirm the inhibitory role of n-LDL and ox-LDL on NO generation and suggest that lipoproteins may induce a decreased uptake of L-arginine. The local depletion of the L-arginine substrate may derange the NO synthase, leading to overproduction of O(2)(-) from oxygen, the other substrate of NO synthase

Tetrahydrobiopterin alters superoxide and nitric oxide release in prehypertensive rats.

Constitutive nitric oxide synthase (cNOS) with insufficient cofactor (6R)-5,6,7,8-tetrahydrobiopterin (H4B) may generate damaging superoxide (O2-). This study was designed to determine whether cNOS-dependent generation of O2- occurs in spontaneously hypertensive rats (SHR) before the onset of hypertension. Aortas from 4-wk-old SHR and Wistar-Kyoto rats were used. cNOS was stimulated by calcium ionophore A23187. In situ measurements of nitric oxide and hydrogen peroxide by electrochemical sensors and O2- production by chemiluminescence method were performed. Isometric tension was continuously recorded. H4B by high performance liquid chromatography and [3H]citrulline assay were determined in homogenized tissue. The A23187-stimulated production of O2- and its superoxide dismutase product hydrogen peroxide were significantly higher, whereas nitric oxide release was reduced in SHR aortas, with opposite results in the presence of exogenous H4B. Furthermore, NG-monomethyl-L-arginine inhibited the generation of cNOS-dependent O2- by approximately 70%. Natural H4B levels were similar in both strains; however, equivalent cNOS activity required additional H4B in SHR. The endothelium-dependent relaxations to A23187 were significantly inhibited by catalase, and enhanced by superoxide dismutase, only in SHR; however, these enzymes had no effect in the presence of H4B. Thus, dysfunctional cNOS may be a source of O2- in prehypertensive SHR and contribute to the development of hypertension and its vascular complications

Tetrahydrobiopterin alters superoxide and nitric oxide release in prehypertensive rats.

Constitutive nitric oxide synthase (cNOS) with insufficient cofactor (6R)-5,6,7,8-tetrahydrobiopterin (H4B) may generate damaging superoxide (O2-). This study was designed to determine whether cNOS-dependent generation of O2- occurs in spontaneously hypertensive rats (SHR) before the onset of hypertension. Aortas from 4-wk-old SHR and Wistar-Kyoto rats were used. cNOS was stimulated by calcium ionophore A23187. In situ measurements of nitric oxide and hydrogen peroxide by electrochemical sensors and O2- production by chemiluminescence method were performed. Isometric tension was continuously recorded. H4B by high performance liquid chromatography and [3H]citrulline assay were determined in homogenized tissue. The A23187-stimulated production of O2- and its superoxide dismutase product hydrogen peroxide were significantly higher, whereas nitric oxide release was reduced in SHR aortas, with opposite results in the presence of exogenous H4B. Furthermore, NG-monomethyl-L-arginine inhibited the generation of cNOS-dependent O2- by approximately 70%. Natural H4B levels were similar in both strains; however, equivalent cNOS activity required additional H4B in SHR. The endothelium-dependent relaxations to A23187 were significantly inhibited by catalase, and enhanced by superoxide dismutase, only in SHR; however, these enzymes had no effect in the presence of H4B. Thus, dysfunctional cNOS may be a source of O2- in prehypertensive SHR and contribute to the development of hypertension and its vascular complications