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Results for “Fluorescence Microscopy”

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At least 1,315 records · Page 73Linked to original sources
PubMed1998

Time-gated fluorescence microscopy in cellular and molecular biology.

An experimental set-up for time-gated fluorescence spectroscopy and microscopy is described, and some recent applications in cellular and molecular biology are summarized. Selective detection of intrinsic fluorophores, in particular nicotinamide adenine dinucleotide (NADH) and flavins was demonstrated in living cells. Non-radiative energy transfer from reduced NADH to the mitochondrial marker rhodamine 123 was evaluated for probing mitochondrial malfunction in living cells. An increase of "energy transfer efficacy" up to a factor 4 was detected after inhibition of enzyme complexes of the respiratory chain. Two different fluorescence lifetimes of calcium orange were evaluated, whose relative intensities depended on calcium concentration. Therefore, fluorescence measured within two different time gates appeared to be suitable for ratio fluorometry of calcium. Time-gated fluorescence spectra of the membrane marker laurdan showed more pronounced changes than steady state spectra when temperature was increased from 24 degrees C to 38 degrees C. This may improve measurements of intracellular temperature. Time-gated detection of small amounts of porphyrins and their discrimination from a large fluorescent background caused by chlorophyll in transgenic tobacco plants again proved the advantages of time-gated fluorescence spectroscopy.

2-Naphthylamine↗
PubMed1999

[Micromorphological findings in jaw bone after radiotherapy. Confocal laser scanning microscopy and fluorescence darkfield microscopy studies].

Early radiation effects on human bone may lead to osteoradionecrosis (ORN). Direct bone cellular lesions [28] as well as fibrous degeneration of blood vessels [21] are considered to be pathologically relevant. Only few data on initial subclinical radiation effects are available. Patients were grouped according to the dose of radiation and clinical findings. Group 1: sound human bone of lower jaw, mostly collected during orthodontic surgery (n = 10 patients); group 2: specimens of lower jaw from patients with ORN (n = 12 patients); group 3: specimens of lower jaw from patients with head and neck cancer who were preoperatively treated with 36 Gy radiation; group 4: specimens of lower jaw from patients with head and neck cancer (n = 9) who were treated with 60-70 Gy radiation. Specimens were studied by confocal laser scanning microscopy (CLSM), by conventional light microscopy (DL) and by fluorescence darkfield microscopy (DFM) after bisbenzimide staining (H 33258) of the viable cellular nuclei. For the correlating study of identical areas in CLSM and DL the specimens were prepared according to the sawing and grinding technique [8]. All the radiated bony specimens, regardless of the dose of radiation, showed areas of extensive or total loss of vitality of the osteocytes. This finding was also evident after 36 Gy and a short interval between radiation and sample collection (group 3). Additionally, in CLSM micromorphologic lesions of the lamellate structure were seen. With these results we can confirm the loss of vitality of the osteocytes as an initial radiation effect as described earlier [10, 23, 28]. In addition to these findings, alteration of the lamellate microstructure was found in the early phase after radiation. The functional and mechanical significance of these findings should be the subject of further studies.

Bone and Bones↗
PubMed1976

Renal test dyes IV. Intravital Fluorescence microscopy and microphotometry of the tubularly secreted dye sulfonefluorescein.

The present study describes for the first time the use of the fluorescent dye sulfonefluorescein for intravital microscopy and microphotometry on the renal surface of rats. With help of this dye tubular secretion can be observed in mammalian kidney in vivo. Tubular secretion can further be quantified with microphotometrical measurements. The molecular structure of sulfonefluorescein is closely related to phenol red, which is known for its tubular secretion. Clearance experiments also show a secretion of sulfonefluorescein. The secretion can be inhibited by probenecid. Ureter ligation causes a strong increase in tubular concentration of the dye. After a temporary ischemia dye accumulation in tubular lumen is greatly reduced.

Animals↗
PubMed2002

Lytic and contracture-lytic prenecrotic damage to cardiomyocytes: photochemical fluorochrome staining and fluorescent microscopy of the myocardium.

Acute prenecrotic damage to cardiomyocytes of lytic (myocytolysis, cytolysis) and contracture-lytic (primary lumpy degradation of myofibrils) types during ischemic and metabolic alteration of the myocardium are detected at the photooptic level by means of photochemical fluorochrome staining and examination under fluorescent light. Comparison of the fluorescent and polarization microscopic pictures showed that changes in cardiomyocytes are determined by local mass redistribution in the sarcomere compartments and transformations of birefraction of myofibrillar system components during necrobiosis. These changes are determined by lysis and coagulation processes in protein structures of sarcomeres.

Animals↗
PubMed1993

A simple optical fiber device for quantitative fluorescence microscopy of single living cells.

A simple and relatively inexpensive system is described for obtaining quantitative fluorescence measurements on single living cells loaded with a fluorescent probe to study cell physiological processes. The light emitted from the fluorescent cells is captured by and transported through an optical fiber. After passage through appropriate filters the light is measured using a photomultiplier tube. The optical fiber is mounted in one of the microscope outlets. Signals derived from the photomultiplier are converted to voltage, amplified, and displayed on a recorder. In the excitation pathway a shutter control unit is mounted. With this control unit the period that the excitation pathway is 'opened' and 'closed' can be adjusted, to reduce cell damage and/or bleaching of the probe. This option allows time-lapse recording of experiments up to 1 h. We have used this set-up with a single and dual emission fluorescent probe to determine intracellular calcium concentrations and pH, respectively. In Fluo-3-loaded K562 target cells bound to natural killer cells, a temporary rise in [Ca2+]i was accompanied by bleb formation. The simple construction of this set-up is interchangeable between different types of fluorescence microscopes and can easily be combined with other microscopy techniques, e.g., patch clamp.

Calcium↗
PubMed2001

Prenecrotic contracture damage in cardiomyocytes: photochemical fluorochrome staining and fluorescent microscopy of the myocardium.

Prenecrotic contracture changes in cardiomyocytes during ischemic and metabolic alteration of the myocardium are detected at the photooptic level by photochemical fluorochrome staining and examination in fluorescent light. Comparison of the fluorescent and polarization microscopic pictures of damaged cardiomyocytes showed relationships between optically active and isotropic constituents of the cell myofibrillar system. Contracture changes are determined by local mass redistribution in contractile compartments and transformations of the myofibril components, caused by protein structure coagulation in cardiomyocyte sarcomers.

Acute Disease↗
PubMed1992

Procion yellow fluorescent microscopy: a new method of studying arterial and venous pathology.

A new means of studying vessel wall pathology is presented. This technique utilizes Procion yellow, a vital fluorescent dye, to stain and delineate the connective elements, matrix, and elastic tissue within the arterial wall. In addition, penetration of the dye into cells provides evidence of membrane pathology. A canine model was used, and clamped segments of femoral artery were stained and examined. The appreciation of this approach for the examination of the vessel wall shows alterations in tissue elements that have not been reported previously. This technique makes possible a unique means of studying connective tissue elements as well as membrane integrity.

Animals↗