Search results for "Iodide"

Biological activities of the LXRα and β agonist, 4β-hydroxycholesterol, and of its isomer, 4α-hydroxycholesterol, on oligodendrocytes: effects on cel…

2013

The biochemical and biological properties of 4β-hydroxycholesterol and of its isomer, 4α-hydroxycholesterol, are not well known. So, we determined the ability of 4α- and 4β-hydroxycholesterol to react with LXRα and LXRβ, and we characterized the activities of these oxysterols on oligodendrocytes which are myelin synthesizing cells. The effects of 4α- and 4β-hydroxycholesterol were studied on 158N murine oligodendrocytes to assess their activities on cell growth and viability, oxidative and inflammatory status. To this end different parameters were used: cell counting with trypan blue; identification of dead cells and cell cycle analysis with propidium iodide; evaluation of mitochondrial dep…

Characterization of cells with different mitochondrial membrane potential during apoptosis.

2005

Background Until now, the simultaneous analysis of several parameters during apoptosis, including DNA content and mitochondrial membrane potential (ΔΨ), has not been possible because of the spectral characteristics of the commonly used dyes. Using polychromatic flow cytometry based upon multiple laser and UV lamp excitation, we have characterized cells with different ΔΨ during apoptosis. Methods U937 cells were treated with the flavonoid quercetin (Qu) and stained with JC-1 to detect ΔΨ, propidium iodide (PI) for cell viability, Hoechst 33342 for DNA content, Annexin V conjugated with Alexa Fluor-647 for detection of phosphatidilserine (PS) exposure, marker of early apoptosis, or Mitotracke…

Natural and induced apoptosis during lymphocyte development in the axolotl

1999

Lymphocytes apoptosis was characterized in a urodele amphibian, the axolotl, by morphology using electron microscopy and by flow cytometry after propidium iodide staining, as well as by biochemical criteria with the detection of DNA ladders after glucocorticoid treatment. The morphological and biochemical features observed in treated axolotls are in accordance with the criteria of apoptosis found in different models of mammalian lymphocyte programmed cell death. The onset of natural apoptosis was then detected by DNA fragmentation in thymus and in spleen during lymphocyte development and ontogenesis. A typical DNA ladder characteristic of apoptosis is detectable in the thymus as early as 5 …

Parthenolide induces caspase-independent and AIF-mediated cell death in human osteosarcoma and melanoma cells

2013

The mechanism of the cytotoxic effect exerted by parthenolide on tumor cells is not clearly defined today. This article shows that parthenolide stimulates in human osteosarcoma MG63 and melanoma SK-MEL-28 cells a mechanism of cell death, which is not prevented by z-VAD-fmk and other caspase inhibitors. In particular treatment with parthenolide rapidly stimulated (1-2 h) reactive oxygen species (ROS) generation by inducing activation of extracellular signal-regulated kinase 1/2 (ERK 1/2) and NADPH oxidase. This event caused depletion of thiol groups and glutathione, NF-κB inhibition, c-Jun N-terminal kinase (JNK) activation, cell detachment from the matrix, and cellular shrinkage. The increa…

Induction of oxiapoptophagy, a mixed mode of cell death associated with oxidative stress, apoptosis and autophagy, on 7-ketocholesterol-treated 158N …

2013

7-Ketocholesterol (7KC) has been suggested to induce a complex mode of cell death on monocytic cells: oxiapoptophagy (OXIdation, APOPTOsis, and autoPHAGY) (Monier et al. (2003) [12]). The aim of the present study, realized on 158N murine oligodendrocytes, was to bring new evidence on this mixed form of cell death. On 158N cells, 7KC induces an overproduction of reactive oxygen species (ROS) revealed by dihydroethidium staining, a loss of transmembrane mitochondrial potential measured with DiOC6(3), caspase-3 activation, and condensation and/or fragmentation of the nuclei which are typical criteria of oxidative stress and apoptosis. Moreover, 7KC enhances cytoplamic membrane permeability to …

Swelling and death of neuronal cells by lactic acid.

1993

Lactacidosis occurring in cerebral ischemia or trauma is a major mechanism of cytotoxic brain edema and brain damage. Respective effects of lactacidosis were currently analyzed in vitro by employment of the murine neuronal cell line, Neuro-2A, in order to obtain a better understanding of specific mechanisms underlying cell swelling and cell death in comparison with glial cells. The cells were suspended in a physiological medium in the presence of lactic acid at increasing concentrations. Levels of acidosis reaching from pH 6.8-5.6 were obtained while other parameters, such as osmolarity and electrolyte concentrations, were maintained in the physiological range. Assessment of cell swelling a…

Biocatalytic formation of synthetic melanin: The role of vanadium haloperoxidases, L-DOPA and iodide

2011

The vanadium haloperoxidase (V-HPO) enzyme, extracted from the brown alga Laminaria saccharina, is able to catalyze the formation of a black precipitate, using as precursor the amino acid L-dopa in the presence of hydrogen peroxide and iodide, in one-pot synthesis. The L-dopa oxidation is a multistep reaction with a crucial role played by the iodide in the enzyme catalyzed peroxidative production of dopachrome, a well known intermediate in the synthesis of melanin. Dopachrome is then converted to a synthetic form of melanin through a polymerization reaction. Factors, such as buffer composition and pH, influence significantly the reaction first steps, but further steps of melanin production …

NEUROPHYSIOLOGICAL AND NEUROCHEMICAL STUDIES WITH THE ISONICOTINOYLHYDRAZONE OF PYRIDOXAL 5-PHOSPHATE.

1964

Luminescence and ultraviolet excitation spectroscopy of SrI2 and SrI2:Eu2+

2013

Abstract We report measurements of luminescence and its ultraviolet excitation spectra in SrI2 and SrI2:Eu2+ at temperatures of 10 and 300 K. Attention is focused on determining the exciton energy and its temperature shift from features of the excitation spectra and limits placed by absorption spectroscopy on a 120 μm thin crystal, on observation of a broadened Eu emission band attributed to trace Eu associated with oxygen in nominally undoped crystals, and on adding observations concerning the 3.4 eV band at low temperature attributed by Pustovarov et al. to the self-trapped exciton.

Optical, infrared and electron-microscopy studies of metallic clusters in layered crystals

2007

Abstract An influence of ( Cd i ) n metallic clusters on the optical absorption and phonon spectra of CdI 2 crystals was studied. Metallic clusters of spherical shape were formed during the growth of non-stoichiometric crystals. Radii of clusters are in range from 10 to 500 nm according to scanning electron microscopy (SEM) data. The density of clusters was estimated from fractal dimension calculations. The fractal dimension of ( Cd i ) n clusters has been found to be varied from 1.488 to 1.793. In the framework of Mie theory the spectral and size dependencies of extinction coefficients were calculated. From the experimentally obtained spectra it is evident that the metallic clusters are re…