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At least 901 records · Page 50Linked to original sources
PubMed1998

Towards automatic cell identification in DIC microscopy.

A general method is proposed for constructing templates of cells in differential interference contrast (DIC) microscopy. This takes account of the optics which generate DIC images, and is applicable to both transparent and semi-transparent cells of simple and complex shapes. Then, a template matching methodology is presented, which uses fast Fourier transforms to fit templates of a range of sizes and orientations to images. For illustration, this is used to automatically identify and measure individual Candida yeast cells in clusters.

Automation↗
PubMed1999

Adhesion-induced receptor segregation and adhesion plaque formation: A model membrane study.

A model system to study the control of cell adhesion by receptor-mediated specific forces, universal interactions, and membrane elasticity is established. The plasma membrane is mimicked by reconstitution of homophilic receptor proteins into solid supported membranes and, together with lipopolymers, into giant vesicles with the polymers forming an artificial glycocalix. The homophilic cell adhesion molecule contact site A, a lipid-anchored glycoprotein from cells of the slime mold Dictyostelium discoideum, is used as receptor. The success of the reconstitution, the structure and the dynamics of the model membranes are studied by various techniques including film balance techniques, micro fluorescence, fluorescence recovery after photobleaching, electron microscopy, and phase contrast microscopy. The interaction of the functionalized giant vesicles with the supported bilayer is studied by reflection interference contrast microscopy, and the adhesion strength is evaluated quantitatively by a recently developed technique. At low receptor concentrations adhesion-induced receptor segregation in the membranes leads to decomposition of the contact zone between membranes into domains of strong (receptor-mediated) adhesion and regions of weak adhesion while continuous zones of strong adhesion form at high receptor densities. The adhesion strengths (measured in terms of the spreading pressure S) of the various states of adhesion are obtained locally by analysis of the vesicle contour near the contact line in terms of elastic boundary conditions of adhesion: the balance of tensions and moments. The spreading pressure of the weak adhesion zones is S approximately 10(-9) J/m(2) and is determined by the interplay of gravitation and undulation forces whereas the spreading pressure of the tight adhesion domains is of the order S approximately 10(-6) J/m(2).

Adsorption↗
PubMed1991

Visualization of bacterial flagella by video-enhanced light microscopy.

We have imaged individual flagellar filaments of Escherichia coli, a motile Streptococcus sp., and Rhizobium meliloti by video-enhanced differential interference-contrast microscopy (Nomarski DIC) and computer-based image processing. This approach has advantages over existing methods in that filaments on living cells can be seen over their entire lengths.

Cell Movement↗
PubMed1997

Combined light microscopy and attenuated total reflection fourier transform infrared spectroscopy for integration of biofilm structure, distribution, and chemistry at solid-liquid interfaces.

Reflected differential interference contrast microscopy and attenuated total reflection Fourier transform infrared spectroscopy were used to obtain complementary data on the structural and chemical properties of a biofilm. This information was obtained nondestructively, quasisimultaneously, and in real time, thereby permitting the verification of time-dependent relationships between the biofilm's population structure, distribution, and interfacial chemistry. The approach offers opportunities to examine these relationships on a variety of substrata in the presence of a bulk aqueous phase under controlled hydrodynamic conditions.

Journal Article↗
PubMed1993

Neurotransmitter-induced exocytosis in goblet and acinar cells of rat nasal mucosa studied by video microscopy.

To investigate the mechanism and neural control of the nasal secretion, we observed the isolated rat nasal mucosa by video-enhanced differential interference contrast microscopy. This technique allowed us to visualize abrupt changes of the individual granules leading to degranulation in the acinar cells and in epithelial goblet cells during secretory stimulation. This image provided evidence that exocytosis is the major mode for regulated secretion in the nasal acinar cells and goblet cells. Acetylcholine (ACh, 0.1-100 microM), substance P (SP, 0.1-10 microM), and vasoactive intestinal peptide (VIP, 0.1-1 microM) induced exocytotic responses and shrinkage of the acinus in a concentration-dependent manner. The effects of ACh (10 microM) on the acinus were clearly inhibited by atropine (5 microM), but the effects of SP (1 microM) and VIP (1 microM) were not. The acinar shrinkage always started before exocytosis, suggesting that the fluid secretion precedes the mucus release. In goblet cells, SP (1 microM) and ACh (10 microM) increased the frequency of exocytotic responses significantly, suggesting that these substances truly play the role of a neurotransmitter for nasal secretion. Histamine (HIST) induced no visible response. The effect of HIST on secretory cells may be neuronally mediated in vivo.

Acetylcholine↗
PubMed1989

Confocal scanning fluorescence microscopy: a new method for phagocytosis research.

An important new method for phagocytosis research, confocal scanning fluorescence light microscopy (CSFM), is demonstrated using fluorescent microspheres ingested by murine macrophages. CSFM, in combination with Nomarski differential interference contrast microscopy (DIC), can resolve microspheres inside cells from microspheres attached to the surface of cells. Further, combined CSFM and DIC images can quantitate phagocytosis by individual cells aggregated together. No other method offers these capabilities. A comparison of CSFM and conventional epifluorescence light microscopy (EFM) images shows that CSFM produces significantly higher-resolution images of microspheres than EFM, primarily because CSFM excludes the out-of-focus light artifacts of EFM.

Animals↗
PubMed1984

Novel morphological approaches for the study of oocyte maturation.

Recent advances in light microscopy are discussed with respect to their application for the study of cell surface, cytoskeletal and organellar changes that occur during meiotic maturation in mammalian oocytes. Three techniques are considered: 1) multiple fluorochrome labeling using immunocytochemical or pharmacological probes to analyze the spatial and temporal disposition of components in oocytes fixed at various stages of meiosis, 2) the use of vital fluorescence stains to study the actual movement of organelles in living oocytes, and 3) video image intensification microscopy of living cells to record dynamic cellular changes with enhanced optical capabilities for fluorescence, polarization and differential interference contrast microscopy. A method is described for simultaneously localizing chromosomes, microtubules and f-actin in fixed rodent oocytes using, respectively, Hoechst 33258, antitubulin antibodies and NBD-phallicidin. Acridine orange and the laser dye rhodamine 123 are employed as vital stains to visualize lysosomes and mitochondria, respectively, in rat oocytes undergoing meiotic maturation. Finally, the application of time-lapse video image intensification microscopy for the study of fluorescently labeled cellular components is discussed with special reference to extended monitoring of cellular organelles for the analysis of dynamic movements of oocyte constituents during maturation.

Actins↗
PubMed1980

[Measurement of the thickness of a histological preparation by the interference method].

The proposed method allows to measure the thickness of microscopic section by combing the method of air optical wedge and smooth alteration of wave length by means of monochromator. The latter provides exact localization of the interference fringe on the desired zone of the wedge thus sparing the necessity of measuring the interference fringe on the wedge.

Histological Techniques↗