Search results for "erythrocytes"
showing 10 items of 218 documents
Role of β1H for the binding of C3b-coated particles to human lymphoid and phagocytic cells
1981
Coating of EAC14oxy23b with highly purified human serum beta 1H globulin (beta 1H) led to acceleration of rosette formation with human peripheral blood lymphocytes (PBL), tonsil lymphocytes, B lymphoblastoid (Raji) cells, granulocytes and monocytes. This reaction was discernible from C3bi-dependent rosette formation. Enhancement of rosette formation of C3b cells by beta 1H was most effective at limiting amounts of C3 per EAC14oxy23b. The beta 1H effect was not due to trace contamination with C3b inactivator. beta 1H-dependent rosette formation with the various lymphoid and phagocytic cells could be suppressed by the F(ab')2 fragment of anti-beta 1H suggesting beta 1H-mediated binding of bet…
Enzymes involved in the dynamic equilibrium of core histone acetylation ofPhysarum polycephalum
1992
DEAE-Scpharose chromatography of extracts from plasmodia of the myxomyccte PI~.~suru~~t ,~/.~crpl~~ho~~ revealed the presence of multiple histone acetyltransferases and histonc deacctylascs. A cyloplasmic histonc acctyltransferase B, specific for histonc H4, and two nuclear acetyltransferases Al and A2 were identilied; Al acetylates all core hislones with a preference for l-13 and H2A. whereas A2 is specific for H3 and also slightly for H2B. Two hislone deacetylases. HDI and HD2, could be discriminated. They differ with respect to subslralc speciliciiy and pH dependence. For the first time the substrate specificity of histonc deacetylascs was determined using HPLC-purilicd individual core h…
Gcn5p is involved in the acetylation of histone H3 in nucleosomes.
1997
Abstract Enzymatic extracts from a gcn5 mutant and wild-type strains of Saccharomyces cerevisiae were chromatographically fractionated and the histone acetyltransferase activities compared. When free histones were used as substrate, extracts from wild-type cells showed two peaks of activity on histone H3 but extracts from gcn5 mutant cells showed only one. With nucleosomes as substrate, the histone acetyltransferase activities present in extracts from the gcn5 mutant strain were not able to modify H3 whereas wild-type cell extracts acetylated intensely this histone. The activity that acetylated nucleosome-bound H3 behaved as a 170-kDa complex. We suggest that Gcn5p represents a catalytic su…
Mobility of Acetylated Histones in Sodium Dodecyl Sulfate–Polyacrylamide Gel Electrophoresis
1999
Abstract We describe an altered mobility for acetylated histone isoforms in sodium dodecyl sulfate–polyacrylamide gel electrophoresis. Isoforms of histones H3 and H4 with a higher acetylation degree have a slightly faster electrophoretic mobility. Since acetylation neutralizes the positive charge of the e-amino group of lysine, without significantly changing the molecular mass of the protein, the acetylation-dependent mobility shift could be explained by the increase of the net negative charge of the SDS–histone complexes. A possible consequence of this differential mobility for the acetylation site determination by protein microsequencing from SDS gels is discussed.
Phosphotransferase properties of human erythrocyte phosphoglycolate phosphatase.
1982
Abstract 1. 1. Human erythrocyte phosphoglycolate phosphatase (PGP) (EC 3.1.3.18) shows transferase properties. Using p -nitrophenylphosphate ( p -NPP) as substrate, methanol, at a concentration of 4.9 M. was the most efficient phosphate acceptor tested (60% phosphate transfer). 2. 2. The branched alcohols i -propanol and i -butanol accept the phosphate better than the unbranched compounds. The acceptor potency is methanol > ethanol > i -propanol > n -propanol > i -butanol > n -butanol. 3. 3. The relative transferase activity could be demonstrated to be independent of substrate concentration, pH. and the inhibitory effect of NaF at 2 and 4 mM. 4. 4. POP shows no transferase activity towards…
Two new biologically active triterpenoidal saponins acylated with salicylic acid from Albizia adianthifolia
2003
International audience; Two new oleanane-type triterpene saponins, adianthifoliosides A (1) and B (2), were isolated from a 95% ethanolic extract of roots of Albizia adianthifolia. Their structures were elucidated mainly by using a combination of 600 MHz 1D and 2D NMR techniques (COSY, NOESY, TOCSY, HSQC, and HMBC) and by FABMS and HRESIMS. Compounds 1 and 2 were characterized as glycosides of acacic acid acylated by an o-hydroxybenzoyl unit. The crude saponin mixture (CSM), compounds 1 and 2 together with 3 and 4 (prosapogenins obtained from the mild alkaline hydrolysate of the CSM), were evaluated for immunomodulatory activity on the Jurkat T cell line and for hemolytic property against s…
AN IL-6/IL-6 SOLUBLE RECEPTOR (IL-6R) HYBRID PROTEIN (H-IL-6) INDUCES EPO-INDEPENDENT ERYTHROID DIFFERENTIATION IN HUMAN CD34+CELLS
2000
H-IL-6 is a hybrid protein constructed to contain IL-6 and its soluble receptor linked by a flexible peptide chain. Here we show that H-IL-6 strongly enhances proliferation of human CD34(+)cells in serum-free liquid culture, and that the majority of the cells generated belong to the erythroid lineage, being positive for the marker Glycophorin A. Conversely, H-IL-6 does not increase the number of myeloid, CD13-positive cells. Comparable effects are observed on progenitors from cord blood and adult peripheral blood. Therefore, H-IL-6 triggers an erythroid-inducing signal in haematopoietic progenitor cells, independently from erythropoietin (EPO).
Digestive vacuoles of Plasmodium falciparum are selectively phagocytosed by and impair killing function of polymorphonuclear leukocytes.
2011
AbstractSequestration of parasitized erythrocytes and dysregulation of the coagulation and complement system are hallmarks of severe Plasmodium falciparum malaria. A link between these events emerged through the discovery that the parasite digestive vacuole (DV), which is released together with infective merozoites into the bloodstream, dually activates the intrinsic clotting and alternative complement pathway. Complement attack occurs exclusively on the membrane of the DVs, and the question followed whether DVs might be marked for uptake by polymorphonuclear granulocytes (PMNs). We report that DVs are indeed rapidly phagocytosed by PMNs after schizont rupture in active human serum. Uptake …
Exposure to malondialdehyde induces an early redox unbalance preceding membrane toxicity in human erythrocytes.
2002
This work investigated the oxidative injury to human red blood cells (RBCs) by the exposure to exogenous malondialdehyde (MDA), in a physiological environment. When a 10% RBC suspension was incubated in autologous plasma, in the presence of 50 microM MDA, 30% of MDA entered into the cells. A time-course study showed that MDA caused early (30-120 min) and delayed (3-18 h) effects. MDA caused a fast depletion of reduced glutathione, and loss of the glucose-6-phosphate dehydrogenase activity, followed by a decrease of HbO2. Accumulation of methemoglobin, and formation of small amounts of hemichrome were later evident. Also, an HbO2-derived fluorescent product was measured in the membrane. The …
Suppression of humoral antibody formation against sheep red blood cells by infections with HSV-2 and the influence of mouse cytomegalovirus
1987
HSV-2 infections suppress the antibody response to HSV-1 but do not impair the mouse cytomegalo virus (MCMV) antibody generating system. In contrast, the sheep red blood cell (SRBC) IgM response is impaired by preinfections with HSV-2 but not with HSV-1. From the time kinetics of this suppression it can be concluded that only a certain submechanism "spills over" to the SRBC system. MCMV suppresses the antibody formation induced by HSV-1.