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Masking Effect (masking + effect)
Selected AbstractsP72 Pigmented patch-test substance and laser Doppler perfusion imagingCONTACT DERMATITIS, Issue 3 2004Bolli Bjarnason Objective:, To investigate if pigment of a dark patch-test substance may affect assessment of perfusion with the laser Doppler imaging technique. Materials:, 13 subjects who previously patch-tested positive with 25% balsam of Peru in petrolatum were re-tested with the same test substance and petrolatum controls applied directly by transparent foils and with much weaker and less pigmented serial doses tested with polyester squares. Readings of perfusion were performed through the test substances and the transparent foils at time intervals up to 4 days while tests were applied and for 5 days following detachment of tests. The instrument set-up of the LDPI was the same as we have suggested for non-pigmented patch-test substances tested on white skin. Results:, Results show that pigment remnants following detachment of the dark pigmented and pasty test substance containing the petrolatum vehicle were prone to affect perfusion assessments by masking detection of perfusion of parts of test sites. A real masking effect is supported by a similar effect with readings of the same tests while they were applied and by no such observable effect with the petrolatum controls or the non-pasty and much less pigmented squares. Conclusion:, The results show that pigment of patch-test substances may affect perfusion assessments with the instrument set-up suggested for non-pigmented substances. [source] Impact of five selected xenobiotics on isolated ammonium oxidizers and on nitrifying activated sludgeENVIRONMENTAL TOXICOLOGY, Issue 4 2006S. N. Dokianakis Abstract Sewage treatment plants (STPs) are usual receptors of xenobiotic compounds that have to be cotreated with municipal wastewaters before being discharged to the water environment. The presence of organic contaminants, such as surfactants, polycyclic aromatic hydrocarbons (PAHs), phthalates, and their primary degradation products in the influents of STPs may inhibit irreversibly sensitive biological processes, such as nitrification. The first step of nitrification, i.e., the oxidation of ammonium to nitrite (nitritification), is particularly sensitive. Inhibition of this step under uncontrolled conditions may completely inhibit biological nitrogen removal. The aim of this work was to study the possible inhibitory effect of five selected xenobiotics on (a) a mixed culture of ammonium-oxidizing bacteria isolated from activated sludge and (b) nitrifying activated sludge directly. The xenobiotics that were tested include nonylphenols (NP), nonylphenolethoxylates (NPEO), linear alkylbenzene sulfonates (LAS), di(2-ethylhexyl) phthalate (DEHP), as a representative phthalate ester, and the PAH phenanthrene. Remarkable inhibitory effects for all tested compounds were observed in this study even at xenobiotic concentrations as low as 1 mg/L. The observed inhibition of xenobiotics on nitrifying activated sludge was less pronounced, because of the masking effect exerted by the sludge flocs, but was still significant for many of the tested substances at concentrations up to 10 mg/L. © 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 310,316, 2006. [source] Assessing the influence of scanner background noise on auditory processing.HUMAN BRAIN MAPPING, Issue 8 2007Abstract Several studies reported decreased signal intensities within auditory areas for experimental designs employing continuous scanner background noise (SBN) in comparison to designs with less or no SBN. This study examined the source for this SBN-induced masking effect of the blood oxygenation level-dependent (BOLD) response by directly comparing two experimental sessions with the same auditory stimulation, which was presented either with or without recorded scanner background noise (RecSBN). Ten subjects listened to a series of four one-syllable words and had to decide whether two of the words were identical. The words were either presented with a silent background or with added RecSBN. This was then contrasted with either silence or RecSBN. A sparse temporal sampling method was used in both sessions, which enabled us to directly assess the influence of RecSBN without varying scanning parameters, acquisition quantities, or auditory stimulations. Our results suggest that previously reported SBN-induced masking of the BOLD response in experimental designs with SBN might be caused by an interaction between increased baseline levels and nonlinearity effects within auditory cortices. Adding SBN to an experimental condition does not enhance signal intensities to the same degree that SBN does when presented with a silent background, and therefore contrasting an experimental and baseline condition that both have SBN may lead to signal decreases. In addition, our study shows this effect is greatest in Heschl's gyrus, but can also be observed in higher-order auditory areas. Hum Brain Mapp, 2006. © 2006 Wiley-Liss, Inc. [source] Increased sialylation of polymeric ,-IgA1 in patients with IgA nephropathyJOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 1 2002Joseph C.K. Leung Abstract The mechanism of mesangial IgA deposition is poorly understood in IgA nephropathy (IgAN). Abnormal glycosylation of carbohydrate moieties in the hinge region of the IgA molecule has recently attracted much attention. In this report, we studied galactosylation and sialylation profiles in ,- and ,-IgA1 from patients with IgAN. Total serum IgA1 was isolated from patients with IgAN or healthy controls by jacalin-affinity chromatography. Six fractions of molecular weight (MW) 50,1,000 kDa were separated by fast protein liquid chromatography (FPLC). Four lectin-binding assays were used to study the sialylation and the presence of terminal galactose or N-acetylgalactosamine (GalNAc) in the O-linked carbohydrate moieties of ,- or ,-IgA1. Maackia amurensis agglutinin (MAA) and Sambucus nigra agglutinin (SNA) lectin recognize ,(2,3)- and ,(2,6)-linked sialic acid, respectively. Peanut agglutinin (PNA) and Helix aspersa (HA) lectin recognize terminal galactose and GalNAc, respectively. Reduced HA was demonstrated in macromolecular , or ,-IgA1 (300,825 kDa) isolated from patients with IgAN (P < 0.05 compared with healthy controls). Lambda- but not ,-IgA1 from patients with IgAN bound less to PNA (P < 0.05). The ,(2,3)-linked sialic acid content in ,- but not ,-IgA1 of MW 150,610 kDa from patients was higher than that of controls (P < 0.005). The ,(2,6)-linked sialic acid content in ,-IgA1 (300,825 kDa) and ,-IgA1 (150,610 kDa) from patients was also higher than that of controls. This unusual glycosylation and sialylation pattern of the ,-IgA1 may have important implications for the pathogenesis of IgAN, as both the masking effect of sialic acid on galactose and the reduced galactosylation will hinder the clearance of macromolecular ,-IgA1 by asialoglycoprotein receptor of hepatocytes. The negative charge from sialic acid may also favor mesangial deposition of macromolecular ,-IgA1 in IgAN. J. Clin. Lab. Anal. 16:11,19, 2002. © 2002 Wiley-Liss, Inc. [source] | ||||||||||