Search results for "T cell"
showing 10 items of 2228 documents
Enzymatic Biosynthesis of Vomilenine, a Key Intermediate of the Ajmaline Pathway, Catalyzed by a Novel Cytochrome P 450-Dependent Enzyme from Plant C…
1995
Abstract Microsomal preparations from Rauwolfia serpentina Benth. cell suspension cultures catalyze a key step in the biosynthesis of ajmaline -the enzymatic hydroxylation of the indole alkaloid vinorine at the allylic C-21 resulting in vomilenine. Vomilenine is an important branch-point intermediate, leading not only to ajmaline but also to several side reactions of the biosynthetic pathway to ajmaline. The investigation of the taxonomical distribution of the enzyme indicated that vinorine hydroxylase is exclusively present in ajmaline-producing plant cells. The novel enzyme is strictly dependent on NADPH2 and O2 and can be inhibited by typical cytochrome P450 inhibitors such as cytochrom…
Novel Stilbene-Based Antileukemic Agents Active in P-Glycoprotein Expressing and Apoptosis-Resistant Acute Leukaemia Cell Lines.
2005
Abstract The stilbene scaffold is a basic element for a number of biologically active natural and synthetic compounds and in accordance with Evans’ definition it can be considered as a privileged structure. One of the most relevant and studied stilbenes is Resveratrol, a phytoalexin present in grapes, endowed with chemopreventive and chemotherapeutic properties and able to induce apoptosis in different cancer cell lines. Since reduced apoptosis has been implicated in the development and progression of malignant tumors and in the occurrence of chemoresistant phenotypes, resveratrol-induced apoptosis might therefore contribute to its antitumor activity. However, resveratrol is a not potent cy…
Tuning antiviral CD8 T-cell response via proline-altered peptide ligand vaccination
2019
AbstractViral escape from CD8+cytotoxic T lymphocyte responses correlates with disease progression and represents a significant challenge for vaccination. Here, we demonstrate that CD8+T cell recognition of the naturally occurring MHC-I-restricted LCMV-associated immune escape variant Y4F is restored following vaccination with a proline-altered peptide ligand (APL). The APL increases MHC/peptide (pMHC) complex stability, rigidifies the peptide and facilitates T cell receptor (TCR) recognition through reduced entropy costs. Structural analyses of pMHC complexes before and after TCR binding, combined with biophysical analyses, revealed that although the TCR binds similarly to all complexes, t…
Pathways and Mechanisms of Human T Cell Activation
1985
The antigen receptor of T lymphocytes was recently identified as a complex consisting of a 90 KD disulfide linked heterodimer, termed Ti which is functionally and structurally associated with three additional molecular components, termed T3 (1). Whereas the former contains clonally unique epitopes and displays peptide variability among T cell clones of distinct specificities, no variability could be detected within any of the known three subunits of T3 (2,3). Monoclonal antibodies to T3 and Ti, respectively, in soluble form were capable of blocking antigen specific clonal T cell responses (4,5). Perhaps more importantly, when coupled to the surface of a solid support these antibodies produc…
The Formation of The Plant Vacuolar System
1999
The plant vacuole is a multifunctional subcellular compartment. In general, the vacuolar system is constituted of a single or few vacuoles. About 80% of the volume of mature plant cells is occupied by vacuoles. These organelles are limited by a single membrane, the tonoplast. According to the cell type and to particular functions, the vacuolar content can vary from a homogeneous consistency to a heterogeneous matrix containing crystalloid structures (Boiler, Wiemken, 1986; Marty et al., 1980). From the biotechnological point of view, the endomembrane system of plants, particularly the ER and vacuoles, can be envisioned as the ultimate environment for stable protein accumulation. Several rep…
Depressed Prostaglandin Release from Peritoneal Cells Induced by a T Cell Adjuvant, Lentinan
1979
Abstract PGE and PGF release from peritoneal exudate cells was studied in mice after injection with two s (1–3) glucans, the antitumor active lentinan and the inactive pachyman. 4 days after injection of both polysaccharides, the spontaneous and phagocytosis-induced PGE and PGF release was markedly suppressed. However, only the immunopotentiator lentinan induced peritoneal exudate cells which exhibited a longer lasting diminished PG release. The data suggest that the T cell adjuvant lentinan may potentiate cellular immune responses by reducing synthesis of immune suppressive prostaglandins from peritoneal exudate cells.
Riesenzellbildung und virusspezifische antigene bei herpesvirus hominis: Informationsflu� von der eltern-DNS
1969
Es wird uber den Einflus von Cytosin-Arabinosid, Hydroxy-Urea und von Mitomycin C auf die Entstehung membranstandiger oder extrahierbarer Antigene, auf die Riesenzellbildung sowie auf die Herpesvirus-bedingte Hemmung der Zell-RNS-Synthese berichtet. Durch die Verabreichung der drei Substanzen wird die Reduplikation der DNS des eingedrungenen Virus vollig blockiert. Trotzdem lassen sich die Phanomene der Riesenzellbildung, der Virus-Antigen-Synthese und der Synthesehemmung der Zell-RNS in vollem Umfange nachweisen.
Inverse correlated 1H-13C in vivo NMR as a probe to follow the metabolism of unlabeled vanillin by plant cell cultures
1997
Abstract Inverse correlated 2D 1H-13C NMR spectroscopy was used to follow the metabolism of vanillin (1) in vivo by plant cell suspension cultures of Nicotiana plumbaginifolia at the natural abundance of 13C. Under the non-invasive conditions four products could be detected: vanillylalcohol (2), vanillinglucoside (3) and the phenolic and benzylic glucosides of vanillylalcohol (4 and 5).
Retinoid acid and analogs as potent inducers of differentiation and apoptosis. New promising chemopreventive and chemotherapeutic agents in oncology
2001
Abstract In this report we will describe the preparation and the biological activity of a novel class of heterocyclic arotinoids endowed with potent cytotoxic and apoptotic acitivity. Structureactivity relationship studies revealed that the different stereochemistry at the C9 double bond of retinoids seems associated with a different biological activity: potent apoptotic activity for the cis-isomers, whereas differentiating activity for the trans structures. An interesting modified Wittig procedure that allows easily to arotinoids will also be described. The substitution of the alkenyl portion with a more flexible oxymethyl or aminomethyl moiety gave compounds with poor activity, whereas i…
Evaluation of the Cytotoxicity of Cholesterol Oxides in Human Colon Cancer Caco-2 Cells
2014
The content of cholesterol oxides (COPs) in foods varies between 0.1 and 294.3 mg/g. These oxides are formed by auto-oxidative enzymatic processes promoted by the heat treatment of food and/or to exposition of them to the presence of oxygen and sunlight during storage. Their importance is that they are associated with pathological processes like apoptosis, dyslipidemia and pro-oxidative states, among others. The objective was to evaluate the cytotoxicity, by means MTT assay, of 7-keto cholesterol (7KC), cholestane-triol (Triol), α-epoxy cholesterol (α-epoxy C), β-epoxy cholesterol (β-epoxy C) in differentiated Caco-2 cells at 120μM for 24, 48 and 72h.Triol was the most cytotoxic COP, with a…