Search results for "complex"
showing 10 items of 5889 documents
Defective T cell receptor/CD3 complex signaling in human type I diabetes
1994
The autoimmune process leading to the destruction of pancreatic β-cells is mediated by T lymphocytes. Peripheral T cells from subjects with preclinical and clinical type I diabetes respond weakly in vitro to lectin stimulation. We, therefore, investigated in a group of newly diagnosed diabetic patients the presence of a defect in the signal transduction pathway of the T cell receptor (TcR)/CD3 complex. Following stimulation with anti-CD3-coupled beads, the proliferative response in diabetic T cells was significantly decreased in comparison with that from normal T cells. Interestingly, addition of either recombinant interleukin (IL)-2 or phorbol 12-myristate 13-acetate to the cell culture wa…
Role of paramagnetic polyconjugated clusters in lignin antioxidant activity(in vitro)
2012
Using physico-chemical methods (EPR, SEC, Py-GC/MS and UV/VIS spectroscopy) and wet chemical analysis, the characteristics of 6 hardwood lignins in terms of functionality, molecular weight and composition of lignin substructures were determined and considered together with the results of DPPH•, ABTS•+ and O2•− antioxidant assays with the aim to understand the relationships governing antioxidant properties of lignin. The strong positive linear correlation between lignin antioxidant capacity in the three assays used and the extent of conjugation of paramagnetic polyconjugated clusters in lignin macromolecules was found. The biological activity of the most active alkaline lignins was assessed …
Evaluation of whole antioxidant defenses of human mononuclear cells by a new in vitro biological test: lack of correlation between erythrocyte and mo…
2009
1873-2933 (Electronic) Journal Article; OBJECTIVES: This work aims to evaluate the resistance of mononuclear cells to oxidative stress using a "KRL" test, formerly utilized to evaluate the resistance of erythrocyte to free radicals. METHODS: The "KRL" test evaluates the resistance to lysis of cells treated by free radicals generated under standardized conditions. RESULTS: We defined new analytical parameters (level of radical production, time course, number of cells) to obtain an accurate assay determining the resistance to oxidative stress of mononuclear cells, in comparison to that of erythrocytes. This test allows the evaluation of change in the redox state of mononuclear cells (improved…
Oxidative stress protection by manganese complexes of tail-tied aza-scorpiand ligands.
2015
The Mn2+ coordination chemistry of double scorpiand ligands in which two polyazacyclophane macrocycles have been connected by pyridine, phenanthroline and bipyridine spacers has been studied by potentiometry, paramagnetic NMR and electrochemistry. All ligands show high stability with Mn2+ and the complexes were formed in a wide pH range. DFT calculations support the structures and coordination geometries derived from the study. A remarkable antioxidant activity was evidenced for these systems by the McCord-Fridovich assay and in Escherichiacoli sodAsodB deficient bacterial cells. The three systems were tested as anti-inflammatory drugs in human macrophages measuring the accumulation of cyto…
Stability and bioaccessibility of EGCG within edible micro-hydrogels. Chitosan vs. gelatin, a comparative study
2016
Micro-hydrogels are very promising systems for the protection and controlled delivery of sensitive bioactives, but limited knowledge exists regarding the impact of this encapsulation on their bioaccessibility. In this work, two different hydrogel-forming biopolymers (gelatin and chitosan) were compared as wall materials for the microencapsulation of a model flavonoid, (−)-epigallocatechin gallate (EGCG). Results showed that gelatin was more adequate as wall material for the encapsulation of EGCG than chitosan, achieving higher encapsulation efficiencies (95% ± 6%), being more effective in delaying EGCG release and degradation in aqueous solution and exhibiting a 7 times higher bioaccessibil…
Novel imine antioxidants at low nanomolar concentrations protect dopaminergic cells from oxidative neurotoxicity.
2009
Strong evidence indicates that oxidative stress may be causally involved in the pathogenesis of Parkinson's disease. We have employed human dopaminergic neuroblastoma cells and rat primary mesencephalic neurons to assess the protective potential of three novel bisarylimine antioxidants on dopaminergic cell death induced by complex I inhibition or glutathione depletion. We have found that exceptionally low concentrations (EC(50) values approximately 20 nM) of these compounds (iminostilbene, phenothiazine, and phenoxazine) exhibited strong protective effects against the toxicities of MPP(+), rotenone, and l-buthionine sulfoximine. Investigating intracellular glutathione levels, it was found t…
Sustainable bioactive pectin-based films to improve fruit safety via a circular economy approach.
2023
This work reports on the valorisation of persimmon (Diospyros kaki Thunb.) for the development of food-grade antiviral coatings against major viral foodborne pathogens, human noroviruses (NoVs) and hepatitis A virus (HAV). Initially, the antiviral activity of polyphenol-rich pectin extracts with abundant non-covalent interactions (PPN), pectin extracts enriched with intact pectin-polyphenol ester and O-glycosyl bonds (PPC) and hydro-ethanolic polyphenol-rich extracts (EPE) was compared. Higher viral reductions were found for the pectin extracts rich in polyphenols, mainly in those containing covalent pectin-polyphenol interactions. This specific extract was mixed with commercial citrus pect…
Leucocytozoon muscicapa n. sp. (Leucocytozoidae: Apicomplexa) from the pied flycatcherFicedula hypoleuca (Pallas) (Passeriformes: Muscicapinae)
1995
Leucocytozoon muscicapa n. sp. is described from the pied flycatcherFicedula hypoleuca (Pallas) (Passeriformes: Muscicapinae) from Finland and compared with other leucocytozoids of the family Muscicapidae.
Apolipoprotein E Regulates Amyloid Formation within Endosomes of Pigment Cells.
2015
International audience; Accumulation of toxic amyloid oligomers is a key feature in the pathogenesis of amyloid-related diseases. Formation of mature amyloid fibrils is one defense mechanism to neutralize toxic prefibrillar oligomers. This mechanism is notably influenced by apolipoprotein E variants. Cells that produce mature amyloid fibrils to serve physiological functions must exploit specific mechanisms to avoid potential accumulation of toxic species. Pigment cells have tuned their endosomes to maximize the formation of functional amyloid from the protein PMEL. Here, we show that ApoE is associated with intraluminal vesicles (ILV) within endosomes and remain associated with ILVs when th…
Haptoglobin interacts with apolipoprotein E and beta-amyloid and influences their crosstalk.
2014
Beta-amyloid accumulation in brain is a driving force for Alzheimer's disease pathogenesis. Apolipoprotein E (ApoE) represents a critical player in beta-amyloid homeostasis, but its role in disease progression is controversial. We previously reported that the acute-phase protein haptoglobin binds ApoE and impairs its function in cholesterol homeostasis. The major aims of this study were to characterize the binding of haptoglobin to beta-amyloid, and to evaluate whether haptoglobin affects ApoE binding to beta-amyloid. Haptoglobin is here reported to form a complex with beta-amyloid as shown by immunoblotting experiments with purified proteins, or by its immunoprecipitation in brain tissues …