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Results for “MICROSCOPY, PHASE CONTRAST”

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At least 955 records · Page 53Linked to original sources
PubMed1988

High-pressure pulsation of central and microvessel pulmonary artery endothelial cells.

We developed an in vitro method of pulsating central and microvessel pulmonary artery endothelial cells that would allow us to study the effects of increased distending pressures over a prolonged period of time. Preservation of the contact-inhibited monolayer was assessed on phase contrast microscopy and, in addition, scanning and transmission electron microscopy (SEM, TEM) were used to determine whether there were alterations in the surface characteristics or intracytoplasmic organelles that suggested cellular damage. The cells used were obtained from Rambouillet lambs, age 3-5 days, anesthetized with halothane and ventilated. The endothelium was harvested from the central pulmonary artery (CPA) by scraping the luminal surface and from the microvessels (MPA) by infusing microcarrier beads 40-140 microns external diameter. After the second passage in culture, the cells were seeded onto the translucent, flexible polyvinylchloride membrane of a transducer dome and grown to confluence. The cell dome was then connected to a blank dome with an attached quartz transducer, to a reservoir, and to stainless steel bellows tubing, all filled with culture medium and affixed to a pulsation generator. By varying the height of the reservoir, the amplitude of excursion of the bellows tubing, and the rate, the cells could be pulsated at a given distending pressure and frequency. Confluent CPA endothelial cells from three lambs and MPA cells from two others were studied after pulsation at both 100/60 and 20/10 mmHg, 60 times/min for 48 h and after nonpulsation. On phase contrast light microscopy and on SEM, the cells remained confluent.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1965

[Demonstration of single elements of the endoplasmic reticulum in the living state].

By means of a special selective preparation technique, it is possible to investigate in thin sections, by electron microscopy, areas of a cell that have been observed in the living state, by phase-contrast microscopy, up to the time of fixation. Structures recorded in the living state can thus be compared to structures seen in electron micrographs. In cells of the fungus Polystictus versicolor, aggregates of membrane systems as well as single cisternae with a diameter of approximately 200 to 300 A can be detected with phase optics. It can be shown, by calculation, that these structures, which are far below the limit of resolution of the light optical system, give enough contrast to be discernible by phase optics. Thus a basis is provided for observing the dynamics of membrane systems which perhaps may contribute to the analysis of the functional significance of these cell components.

Basidiomycota↗
PubMed1982

Improved spatial and temporal resolution in an apparatus for time-lapse phase contrast ciné micrography of cells in vitro.

An apparatus for time-lapse cinemicrography of living animal cells in vitro is described. It has an increased information capacity in comparison with conventional types of equipment in that successful combination of the highest possible spatial resolution with phase contrast microscopy and an improved temporal resolution provided by flash light illumination has been achieved. The interval between exposures of 1/200 s approximately can be reduced to 1/4s using a negative phase-contrast objective of NA 1 . 3. Negative phase-contrast also appeared to be the best technique for imaging of tiny cell surface structures. Thus the new apparatus is suitable for the study of the patterns of cell surface motility in vitro.

Animals↗
PubMedDate not supplied

Comparison of methods of assessing asbestos fiber concentrations.

Dimensional measurement of the counted fibers has important implications for setting of environmental standards to protect workers' health. Results of fiber concentrations as determined by different methods were compared. Each method was used to determine concentration by examining one sector of membrane filter on which fibrous dust was collected in various workplaces. The concentrations measured by the Asbestos International Association (AIA) method for 35 samples were, on the average, greater than the concentrations determined by the modified British Occupational Hygiene Society--Asbestosis Research Council (BOHS-ARC) method. The AIA and modified BOHS-ARC methods were found to be linearly correlated (r = 0.82). The mean of total fiber concentrations obtained by using the indirect transmission electron microscopy (TEM) method was 15.5 times the mean obtained by using the direct TEM method. The difference in concentrations determined by the two TEM methods resulted from disintegration of fiber bundles into single fibers during the ashing and ultrasonifying processes used in the indirect method. At least 83.5% of total fibers observed by TEM escaped detection by phase contrast microscopy.

Air Pollutants, Occupational↗
PubMedDate not supplied

Optical reflectance assay for the detection of biofilm formation.

We describe the protocol for an inexpensive and nondestructive optical reflectance assay for the measurement of biofilm formation. Reflectance data are obtained using an Ocean Optics (Dunedin, Florida) USB 2000 spectrometer with a polychromatic light source. A fiber optic cable is used both for illumination and collection, and Ocean Optics OOIBase32 Platinum software is used for preliminary processing of the data. Differences in reflectance data collected at times ranging from 2 to 24 h distinguish between cell attachment and volume growth for two strains of Enterococci. Confocal scanning laser microscopy imaging is used to confirm these results. Phase contrast microscopy images are also obtained in conjunction with reflectance measurements for several different biofilm specimens. The experiments consider biofilm formation on glass and polystyrene substrata, but the method can be used for many other abiotic substrata of interest, both opaque and nonopaque.

Biofilms↗
PubMed1970

K plus-dependent deplasmolysis of a marine pseudomonad plasmolyzed in a hypotonic solution.

When cells of a marine pseudomonad were washed with a solution consisting of 0.3 m NaCl, 0.05 m MgSO(4), and 0.01 m KCl (complete salts), they maintained their normal morphology. When washed with a solution of 0.05 m MgSO(4), they became plasmolyzed as indicated by both phase and electron microscopy. Suspensions of cells washed with 0.05 m MgSO(4) showed an increase in optical density (OD) when 0.3 m NaCl was added, and this was followed by a decrease in OD upon the further addition of 0.01 m KCl. Salts of other monovalent cations were not effective in replacing K(+) in producing the OD decrease. Phase-contrast microscopy revealed that the increase in OD was accompanied by a decrease in cell size, and the decrease in OD, by an increase in the cell size. Both phase and electron microscopy showed that the K(+)-dependent decrease in OD was accompanied by deplasmolysis of the cells. Na(+) was required in the suspending medium in addition to K(+) to obtain deplasmolysis. The intracellular K(+) concentration in cells which had been washed with complete salts and which had retained their normal morphology was found to be 0.290 m. In cells plasmolyzed by washing with 0.05 m MgSO(4), the intracellular K(+) concentration was 0.004 m. Deplasmolyzed cells contained 0.330 m K(+). The membrane profile of plasmolyzed cells was retained when protoplasts were formed. The protoplasts became spherical if incubated in a solution permitting the deplasmolysis of the parent cells. The evidence obtained indicates that plasmolysis and deplasmolysis under the conditions described was due to the loss and gain, respectively, of K(+) by the cells. The effect of Na(+) could be ascribed to its capacity to control the porosity of the cytoplasmic membrane of this organism.

Biological Transport, Active↗
PubMed2005

Spectral-domain optical coherence phase microscopy for quantitative phase-contrast imaging.

We describe a novel microscopy technique for quantitative phase-contrast imaging of a transparent specimen. The technique is based on depth-resolved phase information provided by common path spectral-domain optical coherence tomography and can measure minute phase variations caused by changes in refractive index and thickness inside the specimen. We demonstrate subnanometer level path-length sensitivity and present images obtained on reflection from a known phase object and human epithelial cheek cells.

Cells, Cultured↗