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System Cells (system + cell)

Distribution by Scientific Domains
Medical Sciences50%

Kinds of System Cells

  • immune system cell
    		•

    Selected Abstracts

    Modulation and metamodulation of synapses by adenosine

    ACTA PHYSIOLOGICA, Issue 2 2010
    J. A. Ribeiro
    Abstract The presence of adenosine in all nervous system cells (neurones and glia) together with its intensive release following insults makes adenosine as a sort of ,regulator' of synaptic communication, leading to the homeostatic coordination of brain function. Besides the direct actions of adenosine on the neurosecretory mechanisms, to tune neurotransmitter release, adenosine receptors interact with other receptors as well as with transporters as part of its attempt to fine-tune synaptic transmission. This review will focus on examples of the different ways adenosine can use to modulate or metamodulate synapses, in other words, to trigger or brake the action of some neurotransmitters and neuromodulators, to cross-talk with other G protein-coupled receptors, with ionotropic receptors and with receptor kinases as well as with transporters. Most of these interactions occur through A2A receptors, which in spite of their low density in some brain areas, such as the hippocampus, may function as amplifiers of the signalling of other mediators at synapses. [source]

    An In Vivo Study of the Host Response to Starch-Based Polymers and Composites Subcutaneously Implanted in Rats

    MACROMOLECULAR BIOSCIENCE, Issue 8 2005
    Alexandra P. Marques
    Abstract Summary: Implant failure is one of the major concerns in the biomaterials field. Several factors have been related to the fail but in general these biomaterials do not exhibit comparable physical, chemical or biological properties to natural tissues and ultimately, these devices can lead to chronic inflammation and foreign-body reactions. Starch-based biodegradable materials and composites have shown promising properties for a wide range of biomedical applications as well as a reduced capacity to elicit a strong reaction from immune system cells in vitro. In this work, blends of corn starch with ethylene vinyl alcohol (SEVA-C), cellulose acetate (SCA) and polycaprolactone (SPCL), as well as hydroxyapatite (HA) reinforced starch-based composites, were investigated in vivo. The aim of the work was to assess the host response evoked for starch-based biomaterials, identifying the presence of key cell types. The tissues surrounding the implant were harvested together with the material and processed histologically for evaluation using immunohistochemistry. At implant retrieval there was no cellular exudate around the implants and no macroscopic signs of an inflammatory reaction in any of the animals. The histological analysis of the sectioned interface tissue after immunohistochemical staining using ED1, ED2, CD54, MHC class II and ,/, antibodies showed positively stained cells for all antibodies, except for ,/, for all the implantation periods, where it was different for the various polymers and for the period of implantation. SPCL and SCA composites were the materials that stimulated the greatest cellular tissue responses, but generally biodegradable starch-based materials did not induce a severe reaction for the studied implantation times, which contrasts with other types of degradable polymeric biomaterials. [source]

    A critical review of the cannabinoid receptor as a drug target for obesity management

    OBESITY REVIEWS, Issue 1 2009
    F. Akbas
    Summary The discovery of cannabinoids, with the well-known stimulatory effect of Cannabis sativa on appetite, has offered a new drug target for obesity treatment. Cannabinoids act on two different receptors: CB1 receptors which are sited in the brain and many peripheral tissues, and CB2 receptors which are primarily found in immune system cells. Cannabinoid receptor antagonists act centrally by blocking CB1 receptors, thereby reducing food intake. Moreover, they probably also act peripherally by increasing thermogenesis and therefore energy expenditure, as has been suggested by animal experiments. Despite these promising mechanisms of action, recent clinical studies examining the effect of the two CB1 receptor antagonists rimonabant and taranabant showed that the attained weight loss did not exceed that attained with other currently approved anti-obesity medications. Moreover, potentially severe psychiatric adverse effects limit their clinical use. As several new CB1 receptor antagonists are presently undergoing development, it remains to be elucidated to what extent they differ in terms of efficacy and safety. This review primarily discusses how close cannabinoid receptor antagonists are to the ideal anti-obesity drug, with respect to their mechanisms of action, clinical effectiveness and safety. [source]

    REVIEW ARTICLE: RCAS1, MT, and Vimentin as Potential Markers of Tumor Microenvironment Remodeling

    AMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 3 2010
    Magdalena Dutsch-Wicherek
    Citation Dutsch-Wicherek M. RCAS1, MT, and vimentin as potential markers of tumor microenvironment remodeling. Am J Reprod Immunol 2010; 63: 181,188 A tumor stimulates the remodeling of its microenvironment for its own survival. To protect its own growth and induce angiogenesis, the tumor changes the structure of extracellular matrix and the function of existing cells; it thus chemo-attracts immune system cells altering their function. In our study, we discuss the potential markers of tumor microenvironment remodeling. For instance, RCAS1 is a protein responsible for tumor escape from host immunologic surveillance that additionally seems to be involved in the remodeling of the microenvironment. Another protein, metallothionein, which is both anti-apoptotic and pro-proliferative, is also responsible for modulating the response of immune system cells. Most likely, the expression of this protein by the fibroblasts of tumor microenvironment is related to the remodeled phenotype of these cells because of the tumor influence on cancer-associated fibroblasts. Lastly, vimentin is a protein that would appear to be the marker for the mesenchymal transition of cells from the epithelial phenotype. These cells seem to acquire the mesenchymal phenotype to migrate so that they can facilitate the development of metastases. Interestingly, the expression of vimentin has also been observed in the tumor microenvironment as well and may serve as a marker of a remodeled stroma in the process of facilitating tumor spread. [source]

    REVIEW ARTICLE: Tolerance Mechanisms in Pregnancy: A Reappraisal of the Role of Class I Paternal MHC Antigens,

    AMERICAN JOURNAL OF REPRODUCTIVE IMMUNOLOGY, Issue 2 2010
    David A. Clark
    Citation Clark DA, Chaouat G, Wong K, Gorczynski RM, Kinsky R. Tolerance mechanisms in pregnancy: a reappraisal of the role of class I paternal MHC antigens. Am J Reprod Immunol 2010; 63: 93,103 Problem, Allogeneic pregnancies have a survival advantage over syngeneic pregnancies, and paternal Class I MHC antigens have been implicated. In humans, HLA-C and HLA-G and E are expressed by subpopulations of fetal trophoblast. In mice, Qa-2, a Class Ib antigen, and classical H-2K antigens have been described. However, the mechanism of prevention of embryo demise in utero has not been critically assessed, and a number of conflicting ideas have not been addressed. The ,, T-cell receptor recognizes peptide bound to the groove in Class I MHC, and peptides have profound effects on the interaction of KIR receptors on T and NK cells with Class I MHC. Methods, Data on prevention of pregnancy loss (abortion) in poly IC-treated mice were reviewed along with information about prevention of losses in the abortion-prone CBA × DBA/2 model. This information was combined with data on paternal antigen expression at different times in pregnancy when key events determining outcome are thought to transpire, and role of tolerance signaling molecules such as CD200. Current data on models supporting a role for ,true' uterine NK cells (TuNKs) versus blood NK cells in the uterus (BuNKs) and role of MHC,KIR interaction were reviewed along with incompatible data in the literature. Results, Whilst paternal Class I MHC appears important, there is an important role for paternal non-MHC minor antigens (small peptides) that bind to the antigen-presenting groove of Class I MHC. BuNKs along with CD8+ T cells and Treg cells appear more important than TuNKs where the role of the latter appears primarily to promote angiogenesis. When during pregnancy the maternal immune system cells are first exposed to paternal Class I + peptide is uncertain, but at the time of implantation, if not earlier, seems likely. Conclusion, Suppression of pregnancy loss by paternal/embryo Class I MHC depends on the presence of paternal peptides. This greatly complicates existing models of Class I,KIR interactions in feto-maternal tolerance or rejection. It is important to consider all the data when devising explanatory models. [source]

    Gene Therapy in HIV-Infected Cells to Decrease Viral Impact by Using an Alternative Delivery Method

    CHEMMEDCHEM, Issue 6 2010
    Teresa Gonzalo Dr.
    Abstract The ability of dendrimer 2G-[Si{O(CH2)2N(Me)2+(CH2)2NMe3+(I,)2}]8 (NN16) to transfect a wide range of cell types, as well as the possible biomedical application in direct or indirect inhibition of HIV replication, was investigated. Cells implicated in HIV infection such as primary peripheral blood mononuclear cells (PBMC) and immortalized suspension cells (lymphocytes), primary macrophages and dendritic cells, and immortalized adherent cells (astrocytes and trophoblasts) were analyzed. Dendrimer toxicity was evaluated by mitochondrial activity, cell membrane rupture, release of lactate dehydrogenase, erythrocyte hemolysis, and the effect on global gene expression profiles using whole-genome human microarrays. Cellular uptake of genetic material was determined using flow cytometry and confocal microscopy. Transfection efficiency and gene knockdown was investigated using dendrimer-delivered antisense oligonucleotides and small interfering RNA (siRNA). Very little cytotoxicity was detected in a variety of cells relevant to HIV infection and erythrocytes after NN16 dendrimer treatment. Imaging of cellular uptake showed high transfection efficiency of genetic material in all cells tested. Interestingly, NN16 further enhanced the reduction of HIV protein 24 antigen release by antisense oligonucleotides due to improved transfection efficiency. Finally, the dendrimer complexed with siRNA exhibited therapeutic potential by specifically inhibiting cyclooxygenase-2 gene expression in HIV-infected nervous system cells. NN16 dendrimers demonstrated the ability to transfect genetic material into a vast array of cells relevant to HIV pathology, combining high efficacy with low toxicity. These results suggest that NN16 dendrimers have the potential to be used as a versatile non-viral vector for gene therapy against HIV infection. [source]