Search results for "fluorescence"
showing 10 items of 2463 documents
Evaluation of the Architect Epstein-Barr Virus (EBV) Viral Capsid Antigen (VCA) IgG, VCA IgM, and EBV Nuclear Antigen 1 IgG Chemiluminescent Immunoas…
2014
ABSTRACTCommercial immunoassays for detecting IgG and IgM antibodies against Epstein-Barr virus (EBV), viral capsid antigens (VCA), and IgGs toward EBV nuclear antigen-1 (EBNA-1) are routinely used in combination to categorize EBV infection status. In this study, we evaluated the performances of the Architect EBV VCA IgG, VCA IgM, and EBNA-1 IgG chemiluminescent microparticle assays (CMIAs) in EBV serological analyses using indirect immunofluorescence assays and anticomplement immunofluorescence assays as the reference methods for VCA IgG, VCA IgM, and EBNA-1 IgG antibody detection, respectively. A total of 365 serum samples representing different EBV serological profiles were included in t…
Ethidium bromide: a fast fluorescent staining procedure for the detection of symbiotic partnership of flagellates and prokaryotes
1999
The hindgut of 'lower' termites harbors a dense population of flagellates and bacteria. The flagellates possess ecto- and endosymbiotic prokaryotes. Most of them are hardly visible in the phase contrast microscope. Staining with the DNA-intercalating agent ethidium bromide visualizes the nuclei of the flagellates as well as the ecto- and endosymbiotic bacteria as red objects. Furthermore, it is possible to distinguish between endosymbiotic methanogens and other bacteria. Following UV excitation, the blue-green autofluorescence of the methanogenic bacteria eclipses the red fluorescence light of the intercalated ethidium bromide. The dye facilitates the observation of symbiotic bacteria and h…
Flow cytometric assay for quantifying opsonophagocytosis and killing of Staphylococcus aureus by peripheral blood leukocytes.
1992
We describe a novel flow cytometric method for quantifying opsonophagocytosis and killing of Staphylococcus aureus in cell-rich plasma obtained after dextran sedimentation of erythrocytes. To analyze opsonophagocytosis, phagocytes were labeled with a phycoerythrin-conjugated monoclonal antibody and were incubated with viable staphylococci containing carboxyfluorescein as a vital fluorescent dye. Phagocytosing cells assumed a dual, orange-green fluorescence. The relative numbers of bacteria associating with phagocytes could be determined by quantifying the decrease of free green fluorescent particles. A parallel incubation of fluorescent bacteria with unlabeled cell-rich plasma was performed…
Characterization of a complex rearrangement involving chromosomes 1, 4 and 8 by fish and array-CGH
2012
Complex chromosomal rearrangements (CCRs) are structural aberrations involving more than two chromosomes with at least three breakpoints. CCRs can be divided into familial and de novo. Balanced CCR are extremely rare in humans and are at high risk of producing unbalanced gametes. Individuals with balanced CCR are usually phenotipically normal but report fertility problems, recurrent miscarriages or congenital anomalies in newborn offsprings as consequence of either meiotic failure or imbalanced chromosomes segregation.We describe the case of an unbalanced CCR involving chromosomes 1, 4 and 8 found in a girl with developmental delay, hexadactilia and microcephaly. The rearrangement, apparent…
Domain Structures in Langmuir-Blodgett Films Investigated by Atomic Force Microscopy
1993
Investigations of phase-separated Langmuir-Blodgett films by atomic force microscopy reveal that on a scale of 30 to 200 micrometers, these images resemble those observed by fluorescence microscopy. Fine structures (less than 1 micrometer) within the stearic acid domains were observed, which cannot be seen by conventional optical microscopic techniques. By applying the force modulation technique, it was found that the elastic properties of the domains in the liquid condensed phase and grains observed within the liquid expanded phase were comparable. Small soft residues in the domains could also be detected. The influence of trace amounts of a fluorescence dye on the micromorphology of monol…
Nile Red lifetime reveals microplastic identity
2020
Microplastic pollution is recognized as a worldwide environmental problem. The increasing daily use and release of plastics into the environment have led to the accumulation of fragmented microplastics, with potentially awful consequences for the environment, and animal and human health. The detection and identification of microplastics are of utmost importance, but available methods are still limited. In this work, a new approach is presented for the analysis of microplastics based on hydrophobic fluorescence staining with Nile Red, using spectrally resolved confocal fluorescence microscopy and fluorescence lifetime imaging microscopy (FLIM). Significant differences were observed in the em…
Identification of microplastics using 4‐dimethylamino‐4′‐nitrostilbene solvatochromic fluorescence
2021
In this work, we introduce the use of 4-dimethylamino-4'-nitrostilbene (DANS) fluorescent dye for applications in the detection and analysis of microplastics, an impendent source of pollution made of synthetic organic polymers with a size varying from less than 5 mm to nanometer scale. The use of this dye revealed itself as a versatile, fast and sensitive tool for readily discriminate microplastics in water environment. The experimental evidences herein presented demonstrate that DANS efficiently absorbs into a variety of polymers constituting microplastics, and its solvatochromic properties lead to a positive shift of the fluorescence emission spectrum according to the polarity of the poly…
Frequency selective excitation of single chromophores within shape-persistent multichromophoric dendrimers
2003
Isolated multichromophoric dendrimers containing four perylenemonoimide chromophores were investigated in a confocal microscope which allowed imaging of the same set of dendrimers over a wide temperature range. Emission spectra at low temperature (2 K) reveal narrow zero-phonon lines although the electron-phonon coupling is not negligible. By using fluorescence excitation spectroscopy, the sharp purely electronic zero-phonon lines of single chromophores within a single multichromophoric unit could be isolated in the frequency domain. Selective excitation into a higher energy chromophoric site is followed by rapid directional energy transfer into the lowest energy site from which emission th…
Dynamic behaviors of fractal-like domains in monolayers
1996
In this paper we report our recent investigations on the morphological evolution of fractal-like domains of the liquid-condensed (LC) phase in lipid monolayers. It is demonstrated that the dimension of the LC domains increases upon continuous illumination of microscope light. The experimental data indicate that the increasing rate of fractal dimension of the LC domains depends on the concentration of fluorescence probes. By analyzing the domain growth process we find that the self-similarity of the pattern disappears gradually during its growth. The possible mechanism behind the observed phenomena is discussed.
A Setup for Microscopic Studies of Ultrasounds Effects on Microliters Scale Samples: Analytical, Numerical and Experimental Characterization
2021
International audience; Sonoporation is the process of cell membrane permeabilization, due to exposure to ultrasounds. There is a lack of consensus concerning the mechanisms of sonoporation: Understanding the mechanisms of sonoporation refines the choice of the ultrasonic parameters to be applied on the cells. Cells’ classical exposure systems to ultrasounds have several drawbacks, like the immersion of the cells in large volumes of liquid, the nonhomogeneous acoustic pressure in the large sample, and thus, the necessity for magnetic stirring to somehow homogenize the exposure of the cells. This article reports the development and characterization of a novel system allowing the exposure to …