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At least 163 records · Page 9Linked to original sources
PubMed1996

Specific inhibition of beta-tryptase expression in a human mast cell line by granulocyte-macrophage colony-stimulating factor produced by airways structural cells.

The growth and differentiation of mast cells are regulated by cytokines produced in tissue microenvironments. We previously reported that mast cells isolated from the epithelial compartment of nasal polyp tissue contain significantly less tryptase when compared with mast cells isolated from the stroma of the same tissue. In an attempt to explore this finding, we analyzed the ability of supernatants obtained from cultured nasal polyp epithelial cells (NP-EpCM) or nasal polyp fibroblasts (NP-FbCM) to regulate the tryptase content of the immature human mast cell line HMC-1. HMC-1 cells were cultured for 7 days in Iscove's modified Dulbecco's medium (IMDM) with 30% of either NP-FbCM or NP-EpCM or 20% MoCM (supernatant of a leukemic T cell line). As assessed by radioimmunoassay and test for enzymatic activity, all three conditioned media were shown to significantly decrease tryptase protein expression in HMC-1, when compared with cultures performed with IMDM alone (NP-EpCM P < 0.001; NP-FbCM P < 0.04; MoCM P < 0.004). In addition, Northern blot analysis demonstrated lower tryptase mRNA levels upon exposure to all three conditioned media tested, suggesting that tryptase downregulation occurs at the transcriptional level. In further studies we found that preincubation of MoCM with anti-granulocyte-macrophage colony-stimulating factor (GM-CSF) completely blocked the observed downregulation of tryptase expression mediated by this conditioned medium. The findings suggest that GM-CSF has a suppressive effect on expression of protease in mast cells, and may thus play a modulatory role in determining the extent of tissue inflammation in allergic airways disease.

Blotting, Northern↗
PubMed2004

A study of pyramidal cell structure in the cingulate cortex of the macaque monkey with comparative notes on inferotemporal and primary visual cortex.

Recent studies have revealed a marked degree of variation in the pyramidal cell phenotype in visual, somatosensory, motor and prefrontal cortical areas in the brain of different primates, which are believed to subserve specialized cortical function. In the present study we carried out comparisons of dendritic structure of layer III pyramidal cells in the anterior and posterior cingulate cortex and compared their structure with those sampled from inferotemporal cortex (IT) and the primary visual area (V1) in macaque monkeys. Cells were injected with Lucifer Yellow in flat-mounted cortical slices, and processed for a light-stable DAB reaction product. Size, branching pattern, and spine density of basal dendritic arbors was determined, and somal areas measured. We found that pyramidal cells in anterior cingulate cortex were more branched and more spinous than those in posterior cingulate cortex, and cells in both anterior and posterior cingulate were considerably larger, more branched, and more spinous than those in area V1. These data show that pyramidal cell structure differs between posterior dysgranular and anterior granular cingulate cortex, and that pyramidal neurons in cingulate cortex have different structure to those in many other cortical areas. These results provide further evidence for a parallel between structural and functional specialization in cortex.

Animals↗
PubMed2002

Unconventional specimen preparation techniques using high resolution low voltage field emission scanning electron microscopy to study cell motility, host cell invasion, and internal cell structures in Toxoplasma gondii.

Apicomplexan parasites employ complex and unconventional mechanisms for cell locomotion, host cell invasion, and cell division that are only poorly understood. While immunofluorescence and conventional transmission electron microscopy have been used to answer questions about the localization of some cytoskeletal proteins and cell organelles, many questions remain unanswered, partly because new methods are needed to study the complex interactions of cytoskeletal proteins and organelles that play a role in cell locomotion, host cell invasion, and cell division. The choice of fixation and preparation methods has proven critical for the analysis of cytoskeletal proteins because of the rapid turnover of actin filaments and the dense spatial organization of the cytoskeleton and its association with the complex membrane system. Here we introduce new methods to study structural aspects of cytoskeletal motility, host cell invasion, and cell division of Toxoplasma gondii, a most suitable laboratory model that is representative of apicomplexan parasites. The novel approach in our experiments is the use of high resolution low voltage field emission scanning electron microscopy (LVFESEM) combined with two new specimen preparation techniques. The first method uses LVFESEM after membrane extraction and stabilization of the cytoskeleton. This method allows viewing of actin filaments which had not been possible with any other method available so far. The second approach of imaging the parasite's ultrastructure and interactions with host cells uses semithick sections (200 nm) that are resin de-embedded (Ris and Malecki, 1993) and imaged with LVFESEM. This method allows analysis of structural detail in the parasite before and after host cell invasion and interactions with the membrane of the parasitophorous vacuole as well as parasite cell division.

Actins↗
PubMed2005

[How to measure the structures, or new stereology. II. Methods of stereological estimation of the absolute dimensions of cell structures in light microscopy].

This review describes modern stereological estimators used for the counting of histological structures and their parameters determination at the light microscopic level. All of these estimators, as a rule, require the preliminary application of a disector for the sampling of images. Nucleator and rotator not only allow unbiased determination of structures absolute dimensions, but also help to save the time used for these operations. In the last years, these stereological estimators are being increasingly used in clinical practice and in electron microscopical analysis.

Cell Count↗
PubMed1990

Interactions of intermediate filaments with cell structures.

Intermediate filaments (IF) are unique components of the cytoskeleton of most eukaryotic cells. Also the nuclear lamins are now recognized to be IF-like proteins, providing the nucleus with a putative skeleton for chromatin attachment. Immunofluorescence and whole-mount electron microscopic studies reveal that IF form a cytoplasmic network that surrounds the nucleus and extends to cell surface, as 'mechanical integrators of cellular space'. It seems however unlikely that IF in the cell accomplish a merely structural role, considering the diversity of IF proteins and the complex regulation of their gene expression. In this work we primarily present electron microscopic data that points to the presence of interactions between IF and several cellular components, namely the nucleus, plasma membrane, other cytoskeletal elements, cytoplasmic organelles and ribonucleoproteins. Although the functional significance of such interactions remains to be demonstrated, assumptions like involvement of IF in information transfer or cytoskeleton-dependent control of gene expression represent attractive hypothesis for future research.

Animals↗
PubMed1965

Electron microscopy of the cell: cell structure and function.

The use of the electron microscope has added much to our knowledge of the cell. The fine structure of the component parts of the nucleus and the cytoplasm is described, and their functions are indicated. The nature and structural modifications of the plasma membrane are illustrated with particular reference to function. To illustrate the interrelationships of the nucleus and cytoplasm, the theory of protein secretion is discussed, the secretion of a particular protein or polypeptide being determined by a particular nucleotide sequence in the desoxyribonucleic acid of a chromosome, that is, by a gene. This information is transferred from nucleus to cytoplasm. It is in the cytoplasm that the majority of the work is performed while the nucleus directs the work of the cell.

Cell Biology↗
PubMed1990

Cell structure and response properties in the trigeminal subnucleus oralis.

Extra- and intracellular recording, electrical stimulation, receptive field mapping, and horseradish peroxidase injection techniques were used to study the structure of functionally identified neurons in trigeminal (V) brainstem subnucleus oralis of the rat. Of 15 heavily labeled cells located within oralis, 4 were local-circuit neurons with receptive fields restricted to either an incisor, guard hairs, one vibrissa, or deep facial tissue (nociceptors). Their morphologies were highly varied, with expansive and spiny dendritic trees and recurrent and intersubnuclear axon collaterals. Oralis local-circuit neurons therefore most closely resembled non-vibrissa-sensitive local-circuit cells in adjacent subnucleus interpolaris. Six other stained cells projected to contralateral thalamus, and two others projected to ipsilateral cerebellum. They typically had intramodality convergent receptive fields (i.e., spanning more than one receptor organ, such as multiple vibrissae or teeth) with widespread dendritic trees, and were therefore indistinguishable from similarly projecting cells in interpolaris. Two other cells projected to the ipsilateral spinal cord, as well as other V brainstem subnuclei. One of these responded to high-threshold mechanical stimulation of teeth; the other was discharged by deflection of one mystacial vibrissa. Their dendrites were very widespread and ended in spiny and bulbous appendages. Local axon collaterals were also extensive. The remaining oralis cell had two axons, one projecting to the thalamus, the other to the spinal cord. Its receptive field expressed convergence from multiple receptor organs, including vibrissae, guard hairs, and skin. Its somadendritic morphology was similar to that of oralis cells projecting only to thalamus. We conclude that, with some exceptions, the extensive dendritic trees, axon branching, convergence, and functional diversity of oralis cells approximate those described previously for functionally equivalent neurons in interpolaris (Jacquin et al., 1989a,b). Such anatomical and physiological properties are rarely seen, however, in nucleus principalis (Jacquin et al., 1988a). The structure and function of three atypical principalis cells with structural and functional characteristics typical of oralis cells are also described. It is argued that such cells are rostrally displaced oralis cells.

Afferent Pathways↗
PubMed1996

Effect of simulated microgravitation on phytohormones and cell structure of tropical orchids.

When studying the effect of two month clinostating on the phytohormonal system of orchids with different types of shoot system branching and different shoot morphology, it was determined that, as a result of simulated microgravitation, endogenous growth regulators changed less in the species with sympodial branching than in species with monopodial branching and without pseudobulbs. Stimulators prevail in the balance of growth regulators in species of the first type and inhibitors in species of the second type. Besides this, comparative analysis of structural organization of juvenile leaf surface tissue of tested orchids was carried out. Variability of size, number and structure of stomatal organization were found according to species belonging to each branching type after clinostating. Electronic microscope studies show some structural peculiarities of epidermal and mesophilous cells.

Gibberellins↗
PubMed2002

Cell structure and mobilization of lipids and proteins from cotyledon under microgravity influence.

The structural-functional organization of cotyledon parenchyma cells of 6-day soybean (Glycine max L.) seedlings that were grown on board the space Shuttle Columbia (STS-87) have been studied. The purafil (KMnO4) was used in the experiment for the removing of some part of ethylene that secretes out from seedlings. There were four variants of the experiment: ground control (+purafil), ground control (-purafil), microgravity (+purafil) and microgravity (-purafil). The electron microscopy, srereological, and pyroantimonate cytochemical methods have been used. It is established the some indices of changes of storage substances in cotyledon parenchyma cells under influence of microgravity. It is displayed in the change of cell ultrastructure, the decrease of relative volume of storage cytoplasmic lipid bodies, a disappearance of storage protein body into vacuole and the redistribution of ionized calcium in cell. It was supposed that microgravity is influenced on the acceleration of storage substances catabolism.

NASA Discipline Plant Biology↗
PubMed1982

Contribution of scanning electron microscopy to viewing internal cell structure.

Freeze-fracture provides a way of opening up cells and tissues for an internal view of cytoplasm and nucleus, and can give an internal view of a cytoplasmic organelle if the plane of fracture cuts through the organelle. Selective removal of soluble or other components is necessary for a deep view of structure at the fracture face. This may be achieved by osmium digestion, or by glycerol extraction, or by delaying fixation until after freeze-fracture and thawing, or by prior treatment with detergent to remove cell membranes and wash out soluble components. Cells may also be ruptured at room temperature, or in certain cases prepared to expose the inner surface of the plasma membrane for scanning electron microscopy (SEM) viewing. The problems and potential of SEM viewing of the cell interior are in certain respects similar to those encountered and derived from TEM replica study of freeze-fractured cells after deep etching. TEM replicas give better resolution, while SEM offers advantages in study of surfaces with considerable depth of structure. Study of fresh material, without fixation or alcohol dehydration, by rapid freezing and deep etching, is increasing our understanding of the artifacts that can be produced by these two preparative steps which are essential to critical point drying, whether used as a preparative step for SEM or for whole-mount high-voltage TEM microscopy.

Animals↗
PubMed2000

Bis(monoacylglycerol) phosphate in rat uterine stromal cells: structural characterization and specific esterification of docosahexaenoic acid.

In rat uterine stromal cells (U(III) cells), docosahexaenoic acid (DHA) was esterified extensively in alkenylacyl-glycerophosphoethanolamine and in an unknown phospholipid accounting for only 0.7% of the total phospholipid. The latter was identified as a bis(monoacylglycerol) phosphate (BMP) using MS. Incorporation studies using C(18:3)n-3 and C(20:5)n-3 demonstrated that BMP had a high specificity to incorporate DHA and C(22) polyunsaturated fatty acids of the (n-3) series. By contrast, polyunsaturated fatty acids of the (n-6) series were never incorporated into BMP. Incubation of U(III) cells with 5 microM DHA for 24 h increased the DHA content of BMP from 36 to 71% of the total acyl chains. [(3)H]DHA-labelled BMP purified as a single TLC spot was resolved into three peaks using HPLC. These peaks were also observed when cells were labelled with [(3)H]phosphatidylglycerol, an exogenous BMP precursor, and with [(33)P]P(i). Electrospray MS of BMP from control cells showed that the first two peaks contained the same molecular species (mainly C(22:6)n-3/C(22:6)n-3 and C(18:1)n-9/C(22:6)n-3) while the third peak mainly contained the C(18:1)n-9/C(18:1)n-9 species. The stereoconfiguration analysis of the compounds revealed an sn-glycero-3-phospho-1'-sn-glycerol configuration for the first peak and sn-glycero-1-phospho-1'-sn-glycerol configurations for the other two. BMP from rat testis was used to establish the positions of the acyl groups. More than 70% of its acyl chains were C(22:5) n-6. It was separated on HPLC into three peaks that co-migrated with the three peaks of BMP from U(III) cells. Lipase activity and NMR analysis of the second peak showed that fatty acids esterified the primary alcohol group on each glycerol moiety. We conclude that the three peaks are stereoisomeric compounds with different acyl-chain locations and may be the result of different metabolic fates depending on subcellular localization.

Animals↗
PubMed1973

Contraction of isolated smooth-muscle cells--structural changes.

The contraction of isolated smooth-muscle cells has been correlated with evagination of the cell membrane, a marked change in myofilament orientation, and a decrease in cellular volume. Both localized and full contractions have been elicited in the same cell by varying the intensity of electrical stimulation. These results may be explained by a model of the smooth-muscle cell in which the contractile apparatus extends between attachment sites on the cell membrane that are relatively closely spaced.

Animals↗
PubMed2002

Influence of surface cell structures on physicochemical properties of Escherichia coli.

The partition of cells in a polyethylene glycol-dextran two phase system was used to compare the relative hydrophobicity of E. coli strains expressing different surface structures. The role of fimbriae and surface antigens on the behavior partition was investigated. The strains expressing PAP fimbriae and/or O-antigen showed a higher surface hydrophobicity than strains which express only type 1 fimbriae and/or R-antigen. No relation was found between K and H antigen and hydrophobicity measurements. The influence of surface structures on electrophoretic mobility has been evaluated. The polysaccharide capsules of AL 213 and AL 499 strains generated a high EPM. For non capsulated E. coli the EPM of rough strains (AL 46, 382) is higher than smooth strain (AL52).

Animals↗