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Results for “Fluorescence Microscopy”

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At least 1,369 records · Page 76Linked to original sources
PubMed1994

Innervation and vasculature of human sweat glands: an immunohistochemistry-laser scanning confocal fluorescence microscopy study.

Secreting tubules, nerves fibers, and blood vessels in human sweat glands (SGs) were fluorescently stained by immunohistochemical and lectin methods for examination with a laser scanning confocal microscope (LSCM). Using these techniques, the three-dimensional distribution of up to three substances within a single specimen was investigated by collecting a series of optical sections for each of three fluorophores. Each SG received several nerve fibers. These branched into delicate bands of one or more axons that ran longitudinal to the sweat tubule then encircled the tubule. A heavy complement of capillaries was interwoven among the sweat tubules. Sweat ducts were accompanied from the SG toward the skin surface by one or two longitudinally oriented nerve fibers and capillaries. Immunoreactive staining of nerves was heaviest with protein gene product 9.5 antibody, but triple labeling showed that immunoreactivity to calcitonin gene-related peptide, vasoactive intestinal polypeptide, and synaptophysin was also present in the same axons. Substance P-immunoreactive axons were sparse in SGs but were present in other areas of the skin. The techniques used have considerable potential in examination of human skin biopsies for diagnosis of disorders affecting the somatic and autonomic nervous systems.

Adolescent↗
PubMed1988

Intracellular distribution of photosensitizing porphyrins measured by video-enhanced fluorescence microscopy.

The intracellular distribution of photosensitizing porphyrins with different amounts of aggregates was measured in a fluorescence microscope using video-intensified detection and image processing. Porphyrin fluorescence was localized in the plasma membrane, cytoplasm, nuclear membrane and nucleoli. The fluorescence intensity in the plasma membrane decreased with increasing aggregation of the photosensitizers. In addition, a redistribution of the porphyrin molecules from the plasma membrane to the nuclear membrane and adjacent intracellular sites was observed with increasing incubation time. Photobleaching of porphyrin fluorescence was most pronounced in the plasma membrane and least efficient within the nucleoli.

Chromatography, High Pressure Liquid↗
PubMed1988

Assay of lectin binding sites in colon cancer-associated mucins: comparison of fluorescence microscopy with a quantitative chromatographic technique.

We have developed a technique for quantitation of binding of fluorescent lectins to glycoconjugates in specimens of tumors derived from cultured human colorectal cancer cells. Tumor cells were injected subcutaneously into nude mice, giving rise to xenografts that resemble primary human colorectal cancers. The tumors were extracted with saline and were subjected to dialysis and lyophilization. Standardized amounts of the tumor extract were then incubated with fluorescent lectins and subjected to gel permeation liquid chromatography to separate lectin bound to high molecular weight glycoproteins from free (unbound) lectin, and were quantitated using a spectrofluorometer. This assay permitted quantitative measurement of the lectin bound to high molecular weight glycoconjugates such as mucin. The results of this assay were compared with the standard histochemical assessment of tissue labeling by fluorescent lectins. A close correlation between the two techniques was found, especially when little or no labeling was present. Greater variations were observed at higher levels of labeling. The quantitative assay confirms that lectins bind to high molecular weight mucin-type glycoconjugates on fixed sections of tumors, and supports the use of semi-quantitative histochemical assessments of tissue labeling.

Adenocarcinoma↗
PubMed1998

Bacillus subtilis cell cycle as studied by fluorescence microscopy: constancy of cell length at initiation of DNA replication and evidence for active nucleoid partitioning.

Fluorescence microscopic methods have been used to characterize the cell cycle of Bacillus subtilis at four different growth rates. The data obtained have been used to derive models for cell cycle progression. Like that of Escherichia coli, the period required by B. subtilis for chromosome replication at 37 degrees C was found to be fairly constant (although a little longer, at about 55 min), as was the cell mass at initiation of DNA replication. The cell cycle of B. subtilis differed from that of E. coli in that changes in growth rate affected the average cell length but not the width and also in the relative variability of period between termination of DNA replication and septation. Overall movement of the nucleoid was found to occur smoothly, as in E. coli, but other aspects of nucleoid behavior were consistent with an underlying active partitioning machinery. The models for cell cycle progression in B. subtilis should facilitate the interpretation of data obtained from the recently introduced cytological methods for imaging the assembly and movement of proteins involved in cell cycle dynamics.

Bacillus subtilis↗
PubMed1999

Video-rate scanning two-photon excitation fluorescence microscopy and ratio imaging with cameleons.

A video-rate (30 frames/s) scanning two-photon excitation microscope has been successfully tested. The microscope, based on a Nikon RCM 8000, incorporates a femtosecond pulsed laser with wavelength tunable from 690 to 1050 nm, prechirper optics for laser pulse-width compression, resonant galvanometer for video-rate point scanning, and a pair of nonconfocal detectors for fast emission ratioing. An increase in fluorescent emission of 1.75-fold is consistently obtained with the use of the prechirper optics. The nonconfocal detectors provide another 2.25-fold increase in detection efficiency. Ratio imaging and optical sectioning can therefore be performed more efficiently without confocal optics. Faster frame rates, at 60, 120, and 240 frames/s, can be achieved with proportionally reduced scan lines per frame. Useful two-photon images can be acquired at video rate with a laser power as low as 2.7 mW at specimen with the genetically modified green fluorescent proteins. Preliminary results obtained using this system confirm that the yellow "cameleons" exhibit similar optical properties as under one-photon excitation conditions. Dynamic two-photon images of cardiac myocytes and ratio images of yellow cameleon-2.1, -3.1, and -3.1nu are also presented.

Biophysical Phenomena↗
PubMed1995

Determination of the Na permeability of the tight junctions of MDCK cells by fluorescence microscopy.

The kinetics of Na movement across the tight junctions of MDCK cells, grown on coverslips and perfused with HEPES or bicarbonate Ringer at 37 degrees C, were investigated after filling the lateral intercellular spaces (LIS) of the epithelium with SBFO, an Na-sensitive fluorescent dye. Dilution and bi-ionic potential measurements showed that MDCK cell tight junctions, although cation-selective, were poorly permeable to N-methyl-D-glucamine Cl (NMDG) but freely permeable to Li. In previous experiments in which Na was replaced by NMDG, a very slow decrease in LIS Na concentration (time constant = 4.8 min) resulted. In the present study, reduction of perfusate Na from 142 to 14 or 24 mM with Na replaced by Li caused LIS Na concentration to decrease with a time constant of 0.43 min. The time constant for Na increase of the LIS was 0.28 min, significantly shorter than that for Na decrease because of the additional component of transcellular Na influx. Ouabain eliminated the transcellular component and equalized the time constants for Na influx and efflux. These results were incorporated into a mathematical model which enabled calculation of the transcellular and paracellular Na fluxes during fluid reabsorption. Regulation of the Na permeability of individual tight junctions by protein kinase A (PKA) was evaluated by treating the monolayers with the Sp-cAMPS, a cAMP substitute, or Rp-cAMPS, a specific inhibitor of PKA. Stimulation of PKA strikingly increased tight junctional permeability while PKA inhibition diminished junctional Na permeability.

Animals↗
PubMed1991

The long-distance effects of brain lesions: visualization of myelinated pathways in the human brain using polarizing and fluorescence microscopy.

We describe several new possibilities for the study of degenerated myelinated tracts in the human central nervous system (CNS). The methods are based on the visualization of myelin breakdown products that show birefringence in polarized light and, when stained with Nile blue and benzpyrene-3,4, exhibit fluorescence. Even after lengthy formalin fixation, the methods permit the localization of anterogradely degenerated tracts in a variety of fiber systems in the brains of patients who died between five and 20 months after the onset of neurological symptoms. Particularly the polarizing technique, because of its simplicity, can be added to the usual neuropathological methods for demonstrating the long-distance effects of a brain lesion. As research tools, these methods would also aid in the study of the anatomical substrate of human neurological symptomatology.

Birefringence↗