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At least 19 recordsLinked to original sources
PubMedDate not supplied

[Registration by dynamic phase microscopy of characteristic frequencies of phase height fluctuations of the myelin nerve fiber at rest and under stimulation].

The method of dynamic phase microscopy was used to study the dynamics of changes in the structure of paranodal and nodal regions of a myelin nerve fiber of brown frog Rana temporaria at rest and under stimulation. Regular structural changes with frequencies of 5.3 and 10.8 Hz in the nodal region of the myelin nerve fiber were detected. A rhythmic excitation leads to additional changes in the structure of the nodal region with a new frequency of 5.6 Hz. It is likely that the regular changes in the nodal region of the myelin nerve induced by rhythmic excitation are due to slow changes in the axolemma (changes in the mode of lateral diffusion of membrane phospholipids), induced by developing trace changes in the membrane potential of the axolemma. The fact that these changes do not occur in the paranodal region of the fibre may indicate either the localization of regular structural changes in the axolemma or the difficulties that arise during the registration of the useful signal in the vicinity of myelin by this method.

Animals↗
PubMedDate not supplied

Doppler flow imaging of cytoplasmic streaming using spectral domain phase microscopy.

Spectral domain phase microscopy (SDPM) is a function extension of spectral domain optical coherence tomography. SDPM achieves exquisite levels of phase stability by employing common-path interferometry. We discuss the theory and limitations of Doppler flow imaging using SDPM, demonstrate monitoring the thermal contraction of a glass sample with nanometer per second velocity sensitivity, and apply this technique to measurement of cytoplasmic streaming in an Amoeba proteus pseudopod. We observe reversal of cytoplasmic flow induced by extracellular CaCl2, and report results that suggest parabolic flow of cytoplasm in the A. proteus pseudopod.

Amoeba↗
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↗
PubMedDate not supplied

Enumeration of previously frozen platelets using the Coulter Counter, phase microscopy, and the technicon optical system.

The Coulter Counter, phase microscopy, and the Technicon optical system were used to enumerate platelets in samples of whole blood, platelet-rich plasma, platelet concentrates before and after addition of DMSO, and on platelet concentrates that had been frozen, thawed, and washed. We observed agreement among the three counting methods when platelet counts were determined in whole blood, platelet-rich plasma, and platelet concentrate before and after DMSO addition. Enumeration after the cryopreservation process, however, showed highly significant differences among the counting systems. Platelet counts on platelet concentrates after freezing the thawing performed with the Coulter Counter were 25 per cent greater than with phase microscopy and 55 per cent greater than with Technicon. Counts with phase microscopy were 30 per cent greater than Technicon values. These data indicate that the method used to enumerate previously frozen platelets affects the apparent platelet count.

Cryoprotective Agents↗
PubMedDate not supplied

[Cooperative processes in mitochondria: registration by dyanmic phase microscopy].

The spectra of phase fluctuations in mitochondria were measured by the method of dynamic phase microscopy. Contrasting components were revealed whose intensity markedly changed at distances of 100-300 nm. Similar frequency components were observed in the spectra of ATP-stimulated fluctuations in liposomes with the incorporated ATPase. The values of the frequency and intensity of contrasting components in spectra of liposomes, mitochondria, and cells are presented. The possibility of determining the position of active enzyme complexes from their characteristic frequencies is discussed.

Adenosine Triphosphatases↗
PubMed2004

Quantitative phase microscopy: a new tool for investigating the structure and function of unstained live cells.

1. The optical transparency of unstained live cell specimens limits the extent to which information can be recovered from bright-field microscopic images because these specimens generally lack visible amplitude-modulating components. However, visualization of the phase modulation that occurs when light traverses these specimens can provide additional information. 2. Optical phase microscopy and derivatives of this technique, such as differential interference contrast (DIC) and Hoffman modulation contrast (HMC), have been used widely in the study of cellular materials. With these techniques, enhanced contrast is achieved, which is useful in viewing specimens, but does not allow quantitative information to be extracted from the phase content available in the images. 3. An innovative computational approach to phase microscopy, which provides mathematically derived information about specimen phase-modulating characteristics, has been described recently. Known as quantitative phase microscopy (QPM), this method derives quantitative phase measurements from images captured using a bright-field microscope without phase- or interference-contrast optics. 4. The phase map generated from the bright-field images by the QPM method can be used to emulate other contrast image modes (including DIC and HMC) for qualitative viewing. Quantitative phase microscopy achieves improved discrimination of cellular detail, which permits more rigorous image analysis procedures to be undertaken compared with conventional optical methods. 5. The phase map contains information about cell thickness and refractive index and can allow quantification of cellular morphology under experimental conditions. As an example, the proliferative properties of smooth muscle cells have been evaluated using QPM to track growth and confluency of cell cultures. Quantitative phase microscopy has also been used to investigate erythrocyte cell volume and morphology in different osmotic environments. 6. Quantitative phase microscopy is a valuable, new, non-destructive, non-interventional experimental tool for structural and functional cellular investigations.

Animals↗
PubMed2006

Full-field swept-source phase microscopy.

We present a full-field phase microscopy technique for quantitative nanoscale surface profiling of samples in reflection. This technique utilizes swept-source optical coherence tomography in a full-field common path interferometer for phase-stable cross-sectional acquisition without scanning. Subwavelength variations in surface sample features are measured without interference from spurious reflections by processing the interferometric phase at a selected depth plane, providing a 1.3 nm stability for high signal-to-noise ratio surface features. Nanoscale imaging was demonstrated by measuring the location of receptor sites on a DNA assay biochip and the surface topography of erythrocytes in a blood smear.

Cells, Cultured↗
PubMed2003

Emulated super-resolution using quantitative phase microscopy.

In the case of coherent illumination, knowledge of the phase and the amplitude of a light wave constitutes complete information. Phase and amplitude information can now be simply acquired using the technique of quantitative phase microscopy. It has been shown that this information allows other imaging modalities to be emulated. In this paper we consider how this information may be used to perform a form of super-resolution by emulating the effect of an annular pupil.

Image Processing, Computer-Assisted↗
PubMed2006

Diffraction phase microscopy for quantifying cell structure and dynamics.

We have developed diffraction phase microscopy as a new technique for quantitative phase imaging of biological structures. The method combines the principles of common path interferometry and single-shot phase imaging and is characterized by subnanometer path-length stability and millisecond-scale acquisition time. The potential of the technique for quantifying nanoscale motions in live cells is demonstrated by experiments on red blood cells.

Cell Movement↗
PubMed2005

Hilbert phase microscopy for investigating fast dynamics in transparent systems.

We introduce Hilbert phase microscopy (HPM) as a novel optical technique for measuring high transverse resolution quantitative phase images associated with optically transparent objects. Because of its single-shot nature, HPM is suitable for investigating rapid phenomena that take place in transparent structures such as biological cells. The potential of this technique for studying biological systems is demonstrated with measurements of red blood cells, and its ability to quantify dynamic processes on a millisecond scale is exemplified with measurements of evaporating micrometer-sized water droplets.

Computer Systems↗
PubMed1963

ULTRAVIOLET AND PHASE MICROSCOPY OF SPORULATING SACCHAROMYCES.

Miller, Glendon R. (Southern Illinois University, Carbondale), Dan O. McClary, and Wilbert D. Bowers, Jr. Ultraviolet and phase microscopy of sporulating Saccharomyces. J. Bacteriol. 85:725-731. 1963.-During active growth, the cytoplasm of yeast cells is densely absorbent to ultraviolet light at 260 mmu, whereas the nucleus is only faintly so, and the vacuole is nonabsorbent. After 24 hr on presporulation medium (about the age of transfer to acetate sporulation medium), the cells manifest many characteristics of starvation. The cytoplasm is weakly absorbent to ultraviolet light except for a dense zone immediately surrounding the vacuole and one or two groups of highly refractile granules clustered on one or both sides of the juncture of the nucleus and the vacuole. After several hours on the acetate sporulation medium, the cells undergo a progressive vacuolation until four or more large vacuoles appear, separated by granular cytoplasm. The nucleus is obscured to ultraviolet light during the vacuolation stage, at which time previous studies have shown its division to occur, and remains so during the rest of the cycle. Photographs of densely granulated cells, at various wavelengths of ultraviolet and visible light, indicated several different types of granules with respect to their absorption spectra. With continued development of the ascus, the granules increase in number until they fill the entire cell and obscure the vacuoles, after which they condense into a compact mass, leaving much of the cell empty. Spores emerge from the granular mass as separate, ultraviolet-absorbent regions without distinguishable cell walls, which seem to be the last structures formed. The rudimentary spores contain a central cluster of dense granules and are separated within the ascus by optically dense, granular partitions which diminish as spore walls are laid down. With the maturing of the ascus, the granules and epiplasm disappear, and the ascus wall is drawn tightly around the more or less homogeneously absorbent spores.

Cell Nucleus↗