Search results for "Complement"

Graphical perception: a case study at the university level

2012

Fanconi's anaemia cells have normal steady-state levels and repair of oxidative DNA base modifications sensitive to Fpg protein

1998

Abstract Cells from Fanconi's anaemia (FA) patients are abnormally sensitive to oxygen. However, a distinct genetic defect in either the cellular defence against reactive oxygen species (ROS) or in their metabolic generation has not been identified to date. Recently, the gene for the human 8-hydroxyguanine (8-oxoG) glycosylase, which removes this oxidative base modification from the genome, has been localized on chromosome 3p25, i.e., in the same region as the FA complementation group D (FAD) gene. We therefore studied the removal of photosensitization-induced 8-oxoG residues from the DNA of FA cells, using Fpg protein, the bacterial 8-oxoG glycosylase, to quantify the lesions by alkaline e…

The catalytic properties of DNA G-quadruplexes rely on their structural integrity

2021

International audience; The influence of the G-quartet structural integrity on the catalytic activity of the G-quadruplex (G4) was investigated by comparing the G4-DNAzyme performances of a series of G4s with a G-vacancy site and a G-triplex (G-tri). The results presented herein not only confirm that the structural integrity of the 3’-end G-quartet is necessary for G4s to be catalytically competent but also show how to remediate G-vacancy-mediated catalytic activity losses via the addition of guanine surrogates in an approach referred to as G-vacancy complementation strategy that is applicable to parallel G4s only. Furthermore, this study demonstrates that the terminal G-quartet could act a…

In vitro synthesis of factor B of the alternative pathway of complement activation by mouse peritoneal macrophages

1976

Factor B of the alternative pathway of complement activation was shown to be synthesized and secreted by unstimulated mouse peritoneal macrophages. The activity of B in the culture supernatants from macrophage monolayers was detected by consumption of C3 in reaction mixtures containing supernatant and guinea pig factors C3, D and insoluble C3b. Using a monospecific antiserum, factor B in concentrated culture supernatants was shown by immunodiffusion and immunoelectrophoresis to be identical to factor B in mouse plasma and to form a characteristic complex with cobra venom factor in the presence of D. A steady rate of factor B secretion was observed for 4 days providing the medium was changed…

Influence of Macrophage Activation on the Synthesis of Complement Components C2, C3, C4

1982

Macrophages are a major site of complement synthesis. In the guinea pig production of complement components C1, C2, C4, C3, D, B, and P by peritoneal macrophages has been demonstrated (reviewed in Ref. 1). Whereas marked differences exist in biological activity between resident, elicited and activated macrophages (2), we investigated whether this holds true for the synthesis and secretion of complement components C2, C3, and C4.

Akupunktur und körperliche Leistungsfähigkeit – Der Einfluss der Nadelung einzelner Akupunkturpunkte auf Parameter der Fahrrad-Spiroergometrie

2004

Zusammenfassung Zielsetzung Untersuchung der Auswirkung der Nadelung einzelner Akupunkturpunkte auf die korperliche Leistungsfahigkeit. Kollektiv 12 mannliche Probanden im Alter von 21–26 Jahren Methodik Fahrrad-Spiroergometrie mit Laktat-Messung Setting insgesamt 6 Testwiederholungen, davor jeweils eine Verum-Akupunktur an verschiedenen Punkten oder eine Placebo-Akupunktur an 5 aufeinanderfolgenden Tagen Design einfach-blinde, Placebo-kontrollierte Studie mit sechsfachem Cross-over Ergebnisse Die Nadelung der Punkte Ma 36 und Di 4 fuhrte in der Tendenz zu einer erhohten maximalen Leistung, jedoch signifikant zu einer erhohten Wattzahl und Sauerstoffaufnahme an der anaeroben Schwelle. Schlu…

Biological properties of carotenoids extracted from Halobacterium halobium isolated from a Tunisian solar saltern

2013

Abstract Background Bioactive molecules have received increasing attention due to their nutraceutical attributes and anticancer, antioxidant, antiproliferative and apoptosis-inducing properties. This study aimed to investigate the biological properties of carotenoids extracted from Archaea. Methods Halophilic Archaea strains were isolated from the brine of a local crystallizer pond (TS7) of a solar saltern at Sfax, Tunisia. The most carotenoid-producing strain (M8) was investigated on heptoma cell line (HepG2), and its viability was assessed by the MTT-test. The cells were incubated with different sub-lethal extract rates, with carotenoid concentrations ranging from 0.2 to 1.5 μM. Antioxida…

Potential multidrug resistance genePOHL: An ecologically relevant indicator in marine sponges

2001

Sponges are sessile filter feeders found in all aquatic habitats from the tropics to the arctic. Against potential environmental hazards, they are provided with efficient defense systems, e.g., protecting chaperones and/or the P-170/multidrug resistance pump system. Here we report on a further multidrug resistance pathway that is related to the pad one homologue (POH1) mechanism recently identified in humans. It is suggested that proteolysis is involved in the inactivation of xenobiotics by the POH1 system. Two cDNAs were cloned, one from the demosponge Geodia cydoniumand a second from the hexactinellid sponge Aphrocallistes vastus. The cDNA from G. cydonium, termed GCPOHL, encodes a deduce…

Protein Tyrosine Nitration Induced by Heme/Hydrogen Peroxide: Inhibitory Effect of Hydroxycinnamoyl Conjugates

2006

The present study was designed to optimize the experimental conditions that govern the heme-catalyzed nitration of protein tyrosine residues by nitrite, and, within this framework, to study the effects of 3,5-dicaffeoylquinic acid and its methyl ester, both of which have been previously reported to be antioxidants and inhibitors of leukocyte functions. Although the presence of hydrogen peroxide is essential in cell-free systems, an excess of this compound was found to be detrimental, so much so that an increase in hemin concentration actually resulted in an inverse effect on the reaction, depending on the levels of fixed hydrogen peroxide. Unlike previous reports on nitrite-induced albumin …

Digestive vacuole of Plasmodium falciparum released during erythrocyte rupture dually activates complement and coagulation.

2012

Abstract Severe Plasmodium falciparum malaria evolves through the interplay among capillary sequestration of parasitized erythrocytes, deregulated inflammatory responses, and hemostasis dysfunction. After rupture, each parasitized erythrocyte releases not only infective merozoites, but also the digestive vacuole (DV), a membrane-bounded organelle containing the malaria pigment hemozoin. In the present study, we report that the intact organelle, but not isolated hemozoin, dually activates the alternative complement and the intrinsic clotting pathway. Procoagulant activity is destroyed by phospholipase C treatment, indicating a critical role of phospholipid head groups exposed at the DV surfa…