Search results for "Cytoplasmic Granule"
showing 10 items of 31 documents
Impaired Platelet Function in Sept8-Deficient Mice In Vitro.
2020
AbstractSeptins (Septs) are a widely expressed protein family of 13 mammalian members, recognized as a unique component of the cytoskeleton. In human platelets, we previously described that SEPT4 and SEPT8 are localized surrounding α-granules and move to the platelet surface after activation, indicating a possible role in platelet physiology. In this study, we investigated the impact of Sept8 on platelet function in vitro using Sept8-deficient mouse platelets. Deletion of Sept8 in mouse platelets caused a pronounced defect in activation of the fibrinogen receptor integrin αIIbβ3, α-granule exocytosis, and aggregation, especially in response to the glycoprotein VI agonist convulxin. In contr…
Taking the stock of granule cargo: Platelet releasate proteomics.
2016
Human platelets are key players in a multitude of physiological and pathological processes. Upon activation they release cargo from different types of granules as well as microparticles in an apparently well-regulated and orchestrated manner. The resulting specific platelet releasates create microenvironments of biologically active compounds and proteins during platelet aggregation and thrombus formation, allowing efficient delivery of growth factors and immune modulators to their sites of effect and enhancing the coagulative response in a positive feedback loop. Thus, platelet releasates play a central role in the regulation of platelet homeostasis and heterotypic cell interaction. Additio…
Gamma delta T cells inhibit in vitro growth of the asexual blood stages of Plasmodium falciparum by a granule exocytosis-dependent cytotoxic pathway …
2004
Several reports have stated the ability of gamma delta T cells to inhibit the growth of the asexual blood stages of Plasmodium falciparum in vitro. However, little information is available about the mechanisms involved. In this study, in vitro systems were used to study the role of the granule exocytosis-dependent cytotoxic pathway in the growth inhibition/killing of P. falciparum by human gamma delta T cells. Our results show that the inhibition requires cell-to-cell contact and that gamma delta T cells kill the asexual blood stages of P. falciparum through a granule exocytosis-dependent cytotoxic pathway after recognition of certain ligands or molecules expressed on the surface of infecte…
Use of electron spectroscopic imaging to determine element composition of the melanin granules in the stria vascularis of the guinea pig.
1998
Electron spectroscopic imaging (ESI) was used to analyze the element content of melanin granules in the stria vascularis seen in ultrathin sections of Spurr-embedded cochleae of the guinea pig. To determine element composition, ESI images were taken at different ionization edges, and non-specific background signals were subtracted digitally by an image processing system. The presence of calcium and nitrogen in the melanin granules could be demonstrated clearly. The calcium identified in the melanin granules was then compared with the spatial distributions of calcium binding sites after the application of an antimonate precipitation method, which was used to localize loosely bound calcium. D…
The histone deacetylase sirtuin 2 is a new player in the regulation of platelet function
2015
SummaryBackground Histone deacetylases (HDACs) play a key role in signaling in many cell types. However, little is known about the participation of HDACs, particularly sirtuins (SIRTs), in platelet reactivity. Objective To investigate the role of HDACs in platelets, we examined the effects of SIRT inhibition on platelet function and protein acetylation in human platelets. Methods We used washed platelets obtained from healthy subjects. Cambinol (SIRT1 and SIRT2 inhibitor), AGK2 (specific SIRT2 inhibitor) and EX527 (specific SIRT1 inhibitor) were used as SIRT inhibitors. Platelets were stimulated with collagen, thrombin, or U46619, and platelet responses were determined according to optical …
Human HepG2 and rat Fao hepatic-derived cell lines show different responses to ciprofibrate, a peroxisome proliferator: analysis by flow cytometry.
1996
Abstract Peroxisome proliferators, and especially hypolipidemic drugs such as ciprofibrate, are known to be hepatocarcinogens in rodents, but their effect in humans is controversial. In an attempt to investigate the effects of ciprofibrate at a cellular level, the analysis of individual whole cells was performed by flow cytometry on samples from two hepatic-derived cell lines: the rat Fao cell line and the human HepG2 cell line. The increase of light scatter signals in rat Fao cells treated for 3 days with ciprofibrate at 250 μMwas related to modifications of intrinsic cellular parameters, such as size and cytoplasmic granularity. Conversely, no variations appeared in human HepG2-treated ce…
Zur Ultrastruktur des Neurofibroms
1970
Elektronenmikroskopische Untersuchung eines Neurofibroms von einem 72 jahrigen Mann mit Morbus Recklinghausen. Der Tumor besteht aus verzweigten Schwannschen Zellen, die in ein kollagenfasriges Zwischengewebe eingelagert sind. Die Schwannschen Zellen sind von einer Basalmembran und einen Reticulinfasernetz umgeben. Wahrscheinlich sind die Schwannschen Zellen eines Neurofibroms befahigt fibrillare Zwischensubstanz zu bilden.
Automatic Counting of Intra-Cellular Ribonucleo-Protein Aggregates in Saccharomyces cerevisiae Using a Textural Approach.
2019
AbstractIn the context of microbiology, recent studies show the importance of ribonucleo-protein aggregates (RNPs) for the understanding of mechanisms involved in cell responses to specific environmental conditions. The assembly and disassembly of aggregates is a dynamic process, the characterization of the stage of their evolution can be performed by the evaluation of their number. The aim of this study is to propose a method to automatically determine the count of RNPs. We show that the determination of a precise count is an issue by itself and hence, we propose three textural approaches: a classical point of view using Haralick features, a frequency point of view with generalized Fourier…
An Ovalbumin Peptide-Specific Cytotoxic T Cell Clone with Antigen Self-Presentation Capacity Uses Two Distinct Mechanisms to Kill Target Cells
1993
Abstract Cloned 10BK.1 T cells with specificity for the ovalbumin peptide OVA257-264 are representative of a novel cell type within the CD8 + subset of T cells. In the presence and in the absence of added antigen presenting cells these T cells react toward antigen (Ag) by proliferation and lymphokine production. These data suggest self-presentation of the Ag by 10BK.1 cells. Here we present evidence that 10BK.1 cells exhibit cytotoxic activity that involves two different cytotoxic effector mechanisms. (i) One mechanism is fast killing activity, apparent within 4 hr. Constitutive mouse T cell-specific proteinase-1 (MTSP-1) activity, constitutive expression of MTSP-1 RNA, increased by Ag chal…
Quantitative electron microscopic observations on Paneth cells of germfree and ex-germfree Wistar rats.
1986
Ultrastructural changes of Paneth cells of germfree (Gf) rats which had been inoculated with bacteria-containing feces from conventionally-reared (SPF) rats were quantitatively examined. 12 and 24 h after inoculation, the Paneth cells showed a striking decrease in the number of secretory granules and the occurrence of large vacuoles. Phagosomes containing bacteria were not seen. After 4 days, the secretory granules reaccumulated and smooth-surfaced apical vesicles increased in number. It is discussed that the large vacuoles may be related to membrane-retrieval events following the massive extrusion of secretory granules whereas the apical vesicles appear to serve this function when exocytos…