Search results for "Cyclic compound"
showing 10 items of 819 documents
THE LIGHT-HARVESTING SYSTEM OF THE UNICELLULAR ALGA Mantoniella squamata (PRASINOPHYCEAE): EVIDENCE FOR THE LACK OF A PHOTOSYSTEM I-SPECIFIC ANTENNA …
1993
The light-harvesting complexes (LHC) were isolated from the unicellular alga Mantoniella squamata (Prasinophyceae) by sucrose-density centrifugation. Beside the major LHC (II), a photosystem I complex was obtained that could be dissociated into a photosystem I core complex and an associated LHC I. In contrast to other chlorophyll b-containing antennae, both LHC II as well as LHC I were observed to be identical with respect to the following features: the molecular weights, the isoelectric points and the retention behavior on anion-exchange chromatography of the apoproteins, the pigment content and the absorption and fluorescence spectra
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…
Cytotoxic effects of oxysterols associated with human diseases: Induction of cell death (apoptosis and/or oncosis), oxidative and inflammatory activi…
2009
Oxysterols resulting from spontaneous or enzymatic oxidation of cholesterol are present in numerous foodstuffs and have been identified at increased levels in the plasma and the vascular walls of patients with cardiovascular diseases, especially in atherosclerotic lesions. Consequently, their role in lipid disorders is widely suspected, but they may also contribute to the development of important degenerative diseases such as Alzheimer's disease, Parkinson's disease, multiple sclerosis, osteoporosis, age-related macular degeneration, and cataract. Since these pathologies can be associated with the presence of apoptotic cells, oxidative and inflammatory processes, and lipid disorders, the ab…
Absence of oxysterol-like side effects in human monocytic cells treated with phytosterols and oxyphytosterols
2012
Oxysterols, found in some commonly consumed foods, can induce a wide range of cytotoxic effects, which have been extensively studied. On the other hand, the side effects of phytosterols and oxyphytosterols are less well-known. Over the past few years, different types of foods have been enriched with phytosterols on the basis of the properties of these compounds that reduce circulating cholesterol levels in certain experimental conditions. It is therefore important to gain better knowledge of the risks and benefits of this type of diet. In this study, conducted in human monocytic U937 cells, the ability of phytosterols (sitosterol, campesterol) and oxyphytosterols (7 beta-hydroxysitosterol, …
Side effects of oxysterols: cytotoxicity, oxidation, inflammation, and phospholipidosis.
2008
Oxysterols are 27-carbon atom molecules resulting from autoxidation or enzymatic oxidation of cholesterol. They are present in numerous foodstuffs and have been demonstrated to be present at increased levels in the plasma of patients with cardiovascular diseases and in atherosclerotic lesions. Thus, their role in lipid disorders is widely suspected, and they might also be involved in important degenerative diseases such as Alzheimer's disease, osteoporosis, and age-related macular degeneration. Since atherosclerosis is associated with the presence of apoptotic cells and with oxidative and inflammatory processes, the ability of some oxysterols, especially 7-ketocholesterol and 7β-hydrox…
Human apolipoprotein A-I natural variants: molecular mechanisms underlying amyloidogenic propensity
2012
Human apolipoprotein A-I (apoA-I)-derived amyloidosis can present with either wild-type (Wt) protein deposits in atherosclerotic plaques or as a hereditary form in which apoA-I variants deposit causing multiple organ failure. More than 15 single amino acid replacement amyloidogenic apoA-I variants have been described, but the molecular mechanisms involved in amyloid-associated pathology remain largely unknown. Here, we have investigated by fluorescence and biochemical approaches the stabilities and propensities to aggregate of two disease-associated apoA-I variants, apoA-IGly26Arg, associated with polyneuropathy and kidney dysfunction, and apoA-ILys107-0, implicated in amyloidosis in severe…
Knowledge Gaps and Research Priorities in Immune Checkpoint Inhibitor–related Pneumonitis. An Official American Thoracic Society Research Statement
2019
Rationale: Immune checkpoint inhibitors (ICIs) have revolutionized cancer care but are associated with unique adverse events, including potentially life-threatening pneumonitis. The diagnosis of ICI-pneumonitis is increasing; however, the biological mechanisms, clinical and radiologic features, and the diagnosis and management have not been well defined. Objectives: To summarize evidence, identify knowledge and research gaps, and prioritize topics and propose methods for future research on ICI-pneumonitis. Methods: A multidisciplinary group of international clinical researchers reviewed available data on ICI-pneumonitis to develop and refine research questions pertaining to ICI-pneumonitis.…
Cercospora beticola toxins. Part XVII. The role of the beticolin/Mg2+ complexes in their biological activity Study of plasma membrane H+-ATPase, vacu…
1996
Beticolin-1 and beticolin-2, yellow toxins produced by the phytopathogenic fungus Cercospora beticola, inhibit the plasma membrane H(+)-ATPase. Firstly, since beticolins are able to form complexes with Mg2+, the role of the beticolin/Mg2+ complexes in the inhibition of the plasma membrane proton pump has been investigated. Calculations indicate that beticolins could exist under several forms, in the H(+)-ATPase assay mixture, both free or complexed with Mg2+. However, the percentage inhibition of the H(+)-ATPase activity is correlated to the concentration of one single form of beticolin, the dimeric neutral complex Mg2H2B2, which appears to be the active form involved in the H(+)-ATPase inh…
Is the repair of oxidative DNA base modifications inducible by a preceding DNA damage induction?
2007
In mammalian cells, 7,8-dihydro-8-oxoguanine (8-oxoG) and some other oxidative guanine modifications are removed from the DNA by base excision repair, which is initiated by OGG1 protein. We have tested whether this repair is inducible in mouse embryonic fibroblasts (MEFs), MCF-7 breast cancer cells and primary human fibroblasts by a pretreatment with the photosensitizer Ro19-8022 plus light, which generates predominantly 8-oxoG, or with methyl methanesulfonate (MMS), which generates alkylated bases and abasic sites (AP sites). The results indicate that the repair rate of the oxidative guanine modifications induced by the photosensitizer was not increased if a priming dose of the oxidative o…
Occupational exposure to chlorinated and petroleum solvents and mycosis fungoides.
2013
OBJECTIVE: To evaluate the potential association between occupational exposure to chlorinated and petroleum solvents and mycosis fungoides (MF).METHODS: A questionnaire on lifetime job history was administered to 100 patients diagnosed with MF and 2846 controls. Odds ratios (ORs) were calculated as the measure of the association between exposure to each specific solvent and MF.RESULTS: In the total sample and in men, cases and controls did not differ in relation to exposure to any of the solvents studied. In women, an association with MF was seen for the highest level of estimated exposure to perchloroethylene (OR = 11.38; 95% confidence interval: 1.04 to 124.85) and for exposure less than …