Search results for "Cell Surface"
showing 10 items of 201 documents
Contribution of sponge genes to unravel the genome of the hypothetical ancestor of Metazoa (Urmetazoa)
2001
Recently the term Urmetazoa, as the hypothetical metazoan ancestor, was introduced to highlight the finding that all metazoan phyla including the Porifera (sponges) are derived from one common ancestor. Sponges as the evolutionarily oldest, still extant phylum, are provided with a complex network of structural and functional molecules. Analyses of sponge genomes from Demospongiae (Suberites domuncula and Geodia cydonium), Calcarea (Sycon raphanus) and Hexactinellida (Aphrocallistes vastus) have contributed also to the reconstruction of the evolutionary position of Metazoa with respect to Fungi. Furthermore, these analyses have provided evidence that the characteristic evolutionary novelties…
Alternative pathway activation of T cells by binding of CD2 to its cell-surface ligand.
1987
Activation of resting T lymphocytes is initiated by the interaction of cell-surface receptors with their corresponding ligands. In addition to activation through the CD3 (T3)-Ti antigen-receptor complex1, recent experiments have demonstrated induction of T-cell proliferation through the CD2 (T11) molecule2–4, traditionally known as the erythrocyte(E)-receptor, through which T cells can bind red blood cells (RBC)5–7. This 'alternative pathway' of T-cell activation2 was observed in vitro in response to combinations of anti-CD2 monoclonal antibodies (mAbs) that bind to distinct epitopes of CD2, such as mAbs against T112 plus T113 (ref. 2). The physiological importance of this activation pathwa…
Cloning and characterization of PRA1, a gene encoding a novel pH-regulated antigen of Candida albicans.
1998
ABSTRACT Candida albicans is an opportunistic fungal pathogen of humans. The cell wall of the organism defines the interface between the pathogen and host tissues and is likely to play an essential and pivotal role in the host-pathogen interaction. The components of the cell wall critical to this interaction are undefined. Immunoscreening of a lambda expression library with sera raised against mycelial cell walls of C. albicans was used to identify genes encoding cell surface proteins. One of the positive clones represented a candidal gene that was differentially expressed in response to changes in the pH of the culture medium. Maximal expression occurred at neutral pH, with no expression d…
Folate-mediated targeting of polymeric conjugates of gemcitabine.
2005
The synthesis of two new macromolecular prodrugs for active tumor targeting was set up. Gemcitabine (2'-deoxy-2',2'-difluorocytidine) was conjugated to alpha,beta-poly(N-2-hydroxyethyl)-DL-aspartamide (PHEA) through succinyl or diglycolyl hydrolysable spacers. The targeting agent folic acid was attached to the macromolecular backbone through the aminocaproic spacer. The two conjugates [PHEA-(5'-succinylgemcitabine)-1'-carboxypentyl-folamide and PHEA-(5'-diglycolyl-gemcitabine)-1'-carboxypentyl-folamide], were purified and extensively characterised by spectroscopic (UV, IR and NMR) and chromatographic analyses to determine the correct chemical structure, the purity degree and the reaction yi…
Functional Role of Lipoprotein Receptors in Alzheimers Disease
2008
The LDL receptor gene family constitutes a class of structurally closely related cell surface receptors fulfilling diverse functions in different organs, tissues, and cell types. The LDL receptor is the prototype of this family, which also includes the VLDLR, ApoER2/LRP8, LRP1 and LRP1B, as well as Megalin/GP330, SorLA/LR11, LRP5, LRP6 and MEGF7. Recently several lines of evidence have positioned the LDL receptor gene family as one of the key players in Alzheimer's disease (AD) research. Initially this receptor family was of high interest due to its key function in cholesterol/apolipoprotein E (ApoE) uptake, with the epsilon4 allele of ApoE as the strongest genetic risk factor for late-onse…
Pharmacological blockade of the fatty acid amide hydrolase (FAAH) alters neural proliferation, apoptosis and gliosis in the rat hippocampus, hypothal…
2015
Endocannabinoids participate in the control of neurogenesis, neural cell death and gliosis. The pharmacological effect of the fatty acid amide hydrolase (FAAH) inhibitor URB597, which limits the endocannabinoid degradation, was investigated in the present study. Cell proliferation (phospho-H3(+) or BrdU(+) cells) of the main adult neurogenic zones as well as apoptosis (cleaved caspase-3(+)), astroglia (GFAP(+)), and microglia (Iba1(+) cells) were analyzed in the hippocampus, hypothalamus and striatum of rats intraperitoneally treated with URB597 (0.3 mg/kg/day) at one dose/4-days resting or 5 doses (1 dose/day). Repeated URB597 treatment increased the plasma levels of the N-acylethanolamine…
Occurrence of a common binding site in Mamestra brassicae, Phthorimaea operculella, and Spodoptera exigua for the insecticidal crystal proteins CryIA…
1997
Specific binding to midgut membrane proteins is required for the toxicity of insecticidal crystal proteins (ICP) from Bacillus thuringiensis. A direct relationship between toxicity and binding has been proposed. It has been hypothesized that sharing of a single receptor by more than one ICP could lead to the occurrence of multiple resistance in the event of an alteration in the common receptor. Binding of CryIA(a), CryIA(b) and CryIA(c), three structurally related ICPs, has been studied in Phthorimaea operculella, Mamestra brassicae and, Spodoptera exigua using brush border membrane vesicles (BBMV) from the midgut tissue. Using iodinated CryIA(b), the three insects showed similar results: o…
Common receptor for Bacillus thuringiensis toxins Cry1Ac, Cry1Fa, and Cry1Ja in Helicoverpa armigera, Helicoverpa zea and Spodoptera exigua
2005
ABSTRACT Binding studies using 125 I-Cry1Ac and biotinylated Cry1Fa toxins indicate the occurrence of a common receptor for Cry1Ac, Cry1Fa, and Cry1Ja in Helicoverpa armigera , Helicoverpa zea , and Spodoptera exigua . Our results, along with previous binding data and the observed cases of cross-resistance, suggest that this pattern seems to be widespread among lepidopteran species.
Vitamin C blocks inflammatory platelet-activating factor mimetics created by cigarette smoking.
1997
Cigarette smoking within minutes induces leukocyte adhesion to the vascular wall and formation of intravascular leukocyte-platelet aggregates. We find this is inhibited by platelet-activating factor (PAF) receptor antagonists, and correlates with the accumulation of PAF-like mediators in the blood of cigarette smoke-exposed hamsters. These mediators were PAF-like lipids, formed by nonenzymatic oxidative modification of existing phospholipids, that were distinct from biosynthetic PAF. These PAF-like lipids induced isolated human monocytes and platelets to aggregate, which greatly increased their secretion of IL-8 and macrophage inflammatory protein-1alpha. Both events were blocked by a PAF r…
Lyophilization of lepidopteran midguts: a preserving method for Bacillus thuringiensis toxin binding studies
2004
Binding assays with brush border membrane vesicles (BBMV) from insect midguts are commonly used in the study of the interactions between Bacillus thuringiensis Cry toxins and their receptors. Collaboration between laboratories often require that frozen insect samples are sent in dry ice. Because of customs restrictions and delays, sample thawing is always a risk and often the biological material becomes ruined during shipping. We have tested lyophilization as an alternative method for preserving insect midguts for binding studies with B. thuringiensis Cry toxins. For this purpose, BBMV were prepared from both frozen and lyophilized midguts from three lepidopteran species: Spodoptera exigua,…