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Results for “CELL STRUCTURE”

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At least 19 recordsLinked to original sources
PubMed2003

Mast cell-IgE-and mast cell-structural cell interactions in allergic airway disease.

Allergic diseases like atopic rhinitis, bronchial asthma, and urticaria are prevalent and on the rise. Mast cells are known to play a central role in the immediate phase reaction of allergic diseases through the IgE-mediated release of a variety of chemical mediators like histamine, leukotrienes, and prostaglandins. On the other hand, T lymphocytes, basophils and eosinophils are thought to be responsible in inducing the late phase response. Yet, recent studies show that the mast cell cannot be simplistically assigned a role in the immediate phase allergic response, and that this cell plays a crucial role in ongoing allergic inflammation, including the development of hyper-responsiveness. In the present article, the author will try to discuss the integrated roles of mast cells in IgE-mediated allergic inflammation with specific emphasis on the roles of mast cell-IgE networking and mast cell-structural cell interactions in the late phase allergic response and chronic allergic inflammation.

Asthma↗
PubMed1995

Rethinking cell structure.

Cell structure, emerging from behind the veil of conventional electron microscopy, appears far more complex than formerly realized. The standard plastic-embedded, ultrathin section can image only what is on the section surface and masks the elaborate networks of the cytoplasm and nucleus. Embedment-free electron microscopy gives clear, high-contrast micrographs of cell structure when combined with removal of obscuring material such as soluble proteins. The resinless ultrathin section is the technique of choice; it is simple and inexpensive, and it uses ordinary electron microscopes. The resulting pictures reveal a world of complex cell structure and function. These images necessarily change our conception of the cytoskeleton, nuclear matrix, mitosis, and the relation of membranes to cytostructure.

Animals↗
PubMed1994

Coupling of cell structure to cell metabolism and function.

The fact that cells make directed decisions regarding how to use energy, i.e., where to direct intracellular particles or where to move, suggests that energy can be, and is, harnessed in specific ways. It is now well established that the chemical reactions of the cell do not occur in nonorganized soup, but rather in the context of ordered structure. The physical components that make up this ordered structure of the cell are part of the tissue matrix, which consists of the dynamic linkages between the skeletal networks of the nucleus (the nuclear matrix), the cytoplasm (the cytoskeleton), and the extracellular environment (the extracellular matrix). To understand gene function and how the energy of the cell is directed towards accomplishing the tasks directed by DNA (gene expression), a further understanding of how cell structure is tied to cellular energy and function is required. We propose that the structural components of the cell harness cellular energy to direct cell functions by providing a dynamic bridge between thermodynamics and gene expression.

Animals↗
PubMed2006

Cell expression of a four extra octarepeat mutated PrPC modifies cell structure and cell cycle regulation.

RK13 cell lines generated to express bovine PrP(C) with a four extra octarepeat insertional mutation (Bo-10ORPrP(C)) show partially insoluble PrP(C) and lower rates of cell growth when compared to either the same cells expressing wild type Bo-6ORPrP(C) or the original RK13 cell line. The expression of Bo-10ORPrP(C) in cell cultures was also associated with changes in cell size and reorganization of the actin cytoskeleton. This last process was reversed by Clostridium difficile toxin-B, a specific inhibitor of small GTPase proteins. Further, in clones expressing Bo-10ORPrP(C), increased proportions of cells at cell cycle stage G2/M were observed. Proteasome inhibitors caused a further expansion of G2/M-stage cells that was more marked in cell lines expressing Bo-10ORPrP(C) than those expressing Bo-6ORPrP(C), while this effect was minimal or null in the original RK13 cell line. Hence, the presence of Bo-10ORPrP(C) in RK13 cells promotes cell cycle arrest at G2/M, and the effect is amplified by proteasome inhibition. These findings suggest a role for PrP(C) in cell morphology and cell cycle regulation, and open new avenues for understanding the mechanisms underlying PrP mutation-associated diseases.

Animals↗
PubMed2006

High-pressure freezing, cellular tomography, and structural cell biology.

Structural cell biology, which we define as electron microscopic analysis of intact cells, suffered a loss of interest and activity following the advances in light microscopy beginning in the 1990s. Interestingly, it is the wealth of detailed observation in the light microscope that is one of the driving forces for the current renewed interest in electron microscopy (EM). A great many cellular details are simply beyond the resolving power of the light microscope. In this article, we describe how electron microscopists are responding to the demands for better preservation of cells and for ways to view cell ultrastructure in three dimensions at high resolution. We discuss how low temperature methods, especially high-pressure freezing and freeze substitution, reduce the artifacts of conventional EM specimen preparation. We also give a brief introduction to cellular electron tomography, a powerful analytical method that can give near-atomic resolution of cell ultrastructure in three-dimensional (3-D) models.

Animals↗
PubMed1997

High D-glucose induces alterations of endothelial cell structure in a cell-culture model.

Diabetes mellitus leads to micro- and macroangiopathy with endothelial dysfunction. To investigate the direct influence of high glucose on endothelial cell structure and possible pharmacologic effects, seven different experimental protocols were carried out on endothelial cells in culture. There were four control groups with either 5 mM D-glucose alone, 5 mM D-glucose plus 15 mM L-glucose (for osmotic control), 5 mM D-glucose plus 500 nM celiprolol, or 5 mM D-glucose plus 57 nM nitrendipine. Three experimental groups had either 20 mM D-glucose alone, 20 mM D-glucose plus 500 nM celiprolol or 20 mM D-glucose plus 57 nM nitrendipine. Treatment of all groups started at the third passage of the cells and lasted until confluence was reached (5-8 days). The endothelial cells were fixed in paraformaldehyde and stained either with hematoxylin-eosin solution, with nitro blue tetrazolium for nicotinamide adenine dinucleotide phosphate (NADPH)- diaphorase staining, or actin staining with phalloidin was carried out. For quantitative analysis of the histologic specimens, the slides were viewed via a microscope and a videocamera. The pictures were converted digitally and could be analyzed with the videopicture-analyzing system, JAVA. In the four control groups, neither treatment with 15 mM L-glucose nor administration of celiprolol or nitrendipine had an effect on cell, cytoplasm, and nuclear area. The number of giant or polynuclear cells and the histochemical NADPH-diaphorase activity were not altered. Incubation of endothelial cells with 20 mM D-glucose for 5-8 days resulted in a significant increase in total and cytoplasmic area, as well as in the number of giant and polynuclear cells, whereas the nuclear area and the NADPH-diaphorase activity were significantly reduced. Concomitant treatment with celiprolol was able to reverse these alterations in endothelial structure significantly but had only a weak effect on the NADPH-diaphorase. Nitrendipine had no beneficial effect on the high D-glucose-induced cell alterations. The actin staining of the control cells showed the typical actin pattern with most of the actin filaments arranged at the periphery of the cells. Administration of 20 mM D-glucose resulted in a disturbance of the actin pattern, with most of the actin filaments now arranged in the middle of the cells. However, neither celiprolol nor nitrendipine exhibited a significant influence on this altered actin structure. High D-glucose treatment over several days thus leads to severe changes in endothelial cell structure, and celiprolol may have a beneficial effect on these hyperglycemia-induced cell alterations.

Actins↗
PubMed2005

Ricinosomes and endosperm transfer cell structure in programmed cell death of the nucellus during Ricinus seed development.

The ricinosome (precursor protease vesicle) is an organelle found exclusively in plant cells. Ricinosomes contain a 45-kDa pro-cysteine endopeptidase (CysEP) with a C-terminal KDEL endoplasmic reticulum retention signal. CysEP is a member of a unique group of papain-type cysteine peptidases found specifically in senescing and ricinosome-containing tissues. During seed development in the castor oil plant (Ricinus communis L.), the cells of the nucellus are killed as the major seed storage organ, the cellular endosperm, expands and begins to accumulate reserves. The destruction of the maternal seed tissues is a developmentally programmed cell death. Terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling revealed that nuclear DNA fragmentation occurs in the nucellar cells adjacent to the expanding endosperm. These cells exhibit ultrastructural features consistent with programmed cell death, including vesiculation of the cytosol, development of irregularly shaped nuclei, vacuolar collapse, and shrinkage of the cytoplasm. Ricinosomes containing the CysEP were identified in the nucellar cells by light and electron microscopy and immunocytochemistry. Both proCysEP and mature CysEP are present in protein extracts of the nucellar tissues during seed development. Upon collapse of the nucellar cells, the content of the ricinosomes is released into the cytoplasm, where the activated CysEP digests the remaining proteinaceous cellular debris. Digestion products of the nucellar cells are presumed taken up by the outermost cells of the endosperm, which have labyrinthine ingrowths of the outer walls typical of transfer cells.

Apoptosis↗
PubMed1990

Cancer cell structure: actin changes in tumour cells--possible mechanisms for malignant tumour formation.

Improvement in treatment of solid tumours is likely to depend on a better knowledge of the biological mechanisms of malignant tumour formation. Over the past few years a great deal of progress has occurred in our understanding of cell biology, and one of the main areas of development has been the cell cytoskeleton. The cytoskeleton contributes to maintenance of cell structure and to a variety of other cell functions. Several studies have implicated one of the elements of the cytoskeleton, the microfilaments, in malignant change, and these microfilaments are directly affected by the activity of some 'oncogenes'. Changes in the control of filament polymerization and organization have been demonstrated in response to the activity of the src oncogene. The protease trypsin has been shown to affect the actin cytoskeleton grossly and illustrates that proteases released in the vicinity of tumours may have a biologically significant effect on the internal structure and stability of the cell. Further investigation of the microfilament system may reveal important clues for future manipulation of the cancer cell and the treatment of the patient with advanced cancer.

Actins↗
PubMed2004

The co-workers of actin filaments: from cell structures to signals.

Cells have various surface architectures, which allow them to carry out different specialized functions. Actin microfilaments that are associated with the plasma membrane are important for generating these cell-surface specializations, and also provide the driving force for remodelling cell morphology and triggering new cell behaviour when the environment is modified. This phenomenon is achieved through a tight coupling between cell structure and signal transduction, a process that is modulated by the regulation of actin-binding proteins.

Actin Cytoskeleton↗
PubMed2004

Effects of corticosteroids on structural cells in asthma and chronic obstructive pulmonary disease.

Structural cells such as airway smooth muscle, myofibroblasts, and fibroblasts play important roles in the pathogenesis of asthma and chronic obstructive pulmonary disease. Although considerable research effort has focused on the effects of steroids on leukocyte function and airway inflammation, few studies have investigated the effects of steroids on structural cell function. There is evidence that structural cells, apart from maintaining the integrity of the bronchial wall, may also participate in airway inflammatory responses. New data suggest that steroids inhibit some but not all proliferative and migratory responses in structural cells. Further, in structural cells the downstream signaling effects altered by glucocorticoids appear to differ from those observed in leukocytes. Therapeutic approaches designed to modulate chemokine and cytokine secretion by structural cells may offer new opportunities to treat diseases characterized by airway obstruction.

Adrenal Cortex Hormones↗