Selective inhibition by the sulfhydryl reagent maleimide of zymosan particle phagocytosis by neutrophils

Yamashita, Tatsuhisa

doi:10.1016/0014-5793(82)80018-5

Cited by 9 publications

(3 citation statements)

References 30 publications

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“…The production of 0% by cells was measured by SOD-inhibitable cytochrome c reduction as in [20]. Neutrophils (5 x 106/ml) were incubated for 10 min at 37°C with 50 pg/ml Con A in the presence of 60pM ferricytochrome c with or without 20pg/ml SOD with constant shaking in a total volume of 3.0 ml PBS containing 1 mM CaC12.…”

Section: Measurement Of Superoxide Anion Releasementioning

confidence: 99%

Effect of maleimide derivatives, sulfhydryl reagents, on stimulation of neutrophil superoxide anion generation with concanavalin A

Yamashita

1983

FEBS Letters

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Using maleimide derivatives with relatively rare side reactions, their effect on stimulation of 02 production by guinea-pig neutrophils with Con A was studied. Showdomycin, a very slowly penetrating agent, did not affect 02 production whereas NEM, a rapidly penetrating agent, markedly inhibited 02 production without interference with binding of Con A to cells. Particulate fractions from neutrophils stimulated with Con A showed markedly increased NADPH-dependent 02 production compared with fractions from unstimulated cells. Treatment of neutrophils with NEM before exposure to Con A inhibited the enhancement of NADPH-dependent 02 production of particulate fractions by Con A. However, particulate fractions from Con A-stimulated and unstimulated cells hardly exhibited reduced NADPH oxidase activity after direct exposure to NEM. Treatment of neutrophils with NEM after activation by Con A had no effect on NADPH-dependent 02 production of particulate fractions. These results indicate that NEM inhibits the activation process of the OS-generating enzyme, probably NADPH oxidase with Con A.

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Section: Measurement Of Superoxide Anion Releasementioning

confidence: 99%

Effect of maleimide derivatives, sulfhydryl reagents, on stimulation of neutrophil superoxide anion generation with concanavalin A

Yamashita

1983

FEBS Letters

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“…The mixture was irradiated with visible light (irradiation energy 80 mW/cm 2 ) under constant stirring. Superoxide concentration was measured in a spectrophotometer (Shimadzu UV-1700) by the increase in maximum absorbance at 550 nm (molar absorption 21/mol/L per centimeter)[37]. …”

Section: Methodsmentioning

confidence: 99%

Lipofuscins prepared by modification of photoreceptor cellsviaglycation or lipid peroxidation show the similar phototoxicity

Донцов¹,

Koromyslova²,

Оstrovsky³

et al. 2016

WJEM

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AIMTo investigate the effect of two ways of lipofuscin production (lipid peroxidation and glycation) on lipofuscin fluorescence characteristics and phototoxicity and to compare them with the properties of natural lipofuscin.METHODSModel lipofuscins were prepared on the basis of bovine photoreceptor outer segments (POS) with bisretinoid A2E addition. One set of samples was prepared from POS modified by lipid peroxidation, while another set from POS modified by glycation with fructose. Fluorescent properties and kinetics of photoinduced superoxide generation of model lipofuscins and human retinal pigment epithelium (RPE) lipofuscin were compared. The fluorescence spectra of samples were measured at 365 nm excitation wavelength and 380-650 emission wavelength.RESULTSThe fluorescence spectra of model lipofuscins are almost the same as the spectrum of natural lipofuscin. Visible light irradiation of both model lipofuscins and natural lipofuscin isolated from RPE cells leads to decrease of a fluorescence maximum at 550 nm and to appearance of a distinct, new maximum at 445-460 nm. The rate of photogeneration of reactive oxygen forms by both model lipofuscins was almost the same and approximately two times less than that of RPE lipofuscin granules.CONCLUSIONThese data suggest that fluorescent characteristics and phototoxicity of lipofuscin granules depend only to an insignificant degree on the oxidative modification of POS proteins and lipids, and generally are defined by the bisretinoid fluorophores contained in them.

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“…The reaction mixture contained 0.1 M K-phosphate buffer, pH 7.6, 100 µM cytochrome c, 0.05% cetyl trimethyl ammonium bromide, and various amounts of water-soluble melanin oxidative degradation products. The mixture was irradiated by blue light from an LED source at an irradiation energy of 4 mW/cm 2 and an irradiation wavelength of 450 nm, with constant stirring, after which the absorption maximum was measured at a wavelength of 550 nm (molar absorption coefficient 21 mM −1 cm −1 ) [40]. Samples were incubated in the dark and samples containing no melanin degradation products were used as controls.…”

Section: Measurement Of Photoinduced Superoxide Radicals Generated By...mentioning

confidence: 99%

Understanding the Mechanism of Light-Induced Age-Related Decrease in Melanin Concentration in Retinal Pigment Epithelium Cells

Dontsov,

Yakovleva,

Vasin

et al. 2023

IJMS

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It is known that during the process of aging, there is a significant decrease in the number of melanosomes in the retinal pigment epithelium (RPE) cells in the human eye. Melanosomes act as screening pigments in RPE cells and are fundamentally important for protection against the free radicals generated by light. A loss or change in the quality of melanin in melanosomes can lead to the development of senile pathologies and aggravation in the development of various retinal diseases. We have previously shown that the interaction between melanin melanosomes and superoxide radicals results in oxidative degradation with the formation of water-soluble fluorescent products. In the present study, we show, using fluorescence analysis, HPLC, and mass spectrometry, that visible light irradiation on melanolipofuscin granules isolated from RPE cells in the human eye results in the formation of water-soluble fluorescent products from oxidative degradation of melanin, which was in contrast to lipofuscin granules and melanosomes irradiation. The formation of these products occurs as a result of the oxidative degradation of melanin by superoxide radicals, which are generated by the lipofuscin part of the melanolipofuscin granule. We identified these products both in the composition of melanolipofuscin granules irradiated with visible light and in the composition of melanosomes that were not irradiated but were, instead, oxidized by superoxide radicals. In the melanolipofuscin granules irradiated by visible light, ions that could be associated with melanin oxidative degradation products were identified by applying the principal component analysis of the time-of-flight secondary ion mass spectrometry (ToF-SIMS) data. Degradation of the intact melanosomes by visible light is also possible; however, this requires significantly higher irradiation intensities than for melanolipofuscin granules. It is concluded that the decrease in the concentration of melanin in RPE cells in the human eye with age is due to its oxidative degradation by reactive oxygen species generated by lipofuscin, as part of the melanolipofuscin granules, under the action of light.

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Selective inhibition by the sulfhydryl reagent maleimide of zymosan particle phagocytosis by neutrophils

Cited by 9 publications

References 30 publications

Effect of maleimide derivatives, sulfhydryl reagents, on stimulation of neutrophil superoxide anion generation with concanavalin A

Effect of maleimide derivatives, sulfhydryl reagents, on stimulation of neutrophil superoxide anion generation with concanavalin A

Lipofuscins prepared by modification of photoreceptor cellsviaglycation or lipid peroxidation show the similar phototoxicity

Understanding the Mechanism of Light-Induced Age-Related Decrease in Melanin Concentration in Retinal Pigment Epithelium Cells

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