Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “FLUORESCENCE”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 649 records · Page 36Linked to original sources
PubMed2000

Electrically driven microseparation methods for pesticides and metabolites: IV. Effects of the nature of fluorescent labels on the enantioseparation of pesticides and their degradation products by capillary zone electrophoresis with UV and laser-induced fluorescence detection.

Three different fluorescent tags, namely 5-aminonaphthalene-1-sulfonic acid (ANSA), 7-aminonaphthalene-1,3-disulfonic acid (ANDSA), and 8-aminonaphthalene-1,3,6-trisulfonic acid (ANTS) were evaluated in the precolumn derivatization of some chiral phenoxy acid herbicides, some chiral transformation products of pyrethroid insecticides, and in their subsequent enantiomeric separation by capillary electrophoresis (CE). The electrolyte systems consisted of sodium phosphate buffers containing chiral surfactants such as octylglucoside (OG) or octylmaltoside (OM) at concentrations above the critical micellar concentration (CMC). Among the three different tags investigated, the ANDSA derivatives of the various solutes were more readily enantioseparated than the ANSA and ANTS derivatives. While the tagging with ANSA allowed the enantioseparation of a limited number of the chiral solute-ANSA derivatives investigated, the ANTS derivatization yielded derivatives that could not be enantioseparated. The polarity of the three different tags increases by increasing the number of sulfonic acid groups in the molecule in the following order: ANSA (one sulfonic acid) < ANDSA (two sulfonic acid groups) < ANTS (three sulfonic acid groups). This seems to indicate that the intermediate polarity of the ANDSA tag allowed more equitable nonpolar/polar interactions of the ANDSA-derivatized solutes with the OG or OM micelles, and consequently the enantioseparation of the solute-ANDSA derivatives. Thus, there is a solute polarity window for enantioresolution with alkylglycoside micelle by CE. Solutes of intermediate polarity that undergo more equitable nonpolar/polar interactions with the micelles exhibited chiral separations.

Electrophoresis, Capillary↗
PubMed2002

Micellar electrokinetic chromatography with diode laser-induced fluorescence detection as a tool for investigating the fluorescence labeling of proteins.

We describe the use of micellar electrokinetic chromatography with diode laser-induced fluorometry (MEKC-DLIF) as a tool to characterize a labeling reaction between sulfoindocyanine succinimidyl ester (Cy5), a cyanine fluorescent dye, and a model protein, bovine serum albumin (BSA). To decrease the influence of imprecise injection, methylene blue was added as an internal standard. Labeled BSA was completely separated from the unconjugated Cy5, and methylene blue under optimized conditions. A kinetic study of the reaction was performed by changing some parameters, such as reaction buffer pH, reaction buffer concentration and the initial concentration of BSA. A comparison between the current method and traditional methods was made.

Animals↗
PubMed1992

Platelet aggregation inhibiting and anticoagulant effects of oligoamines, XVII: Oligoamines with fluorescent properties. Part A: Fluorescent bridged nitrogen functions.

Eleven dimethanamines and one disydnonimine with fluorescent properties have been synthesized. All of them show antiplatelet activities (IC50, Born-test) in concentrations between 14-75 mumol/L. Five of them inhibited fibrin formation induced by thromboplastin by more than 75% in a 200 mu molar concentration. Both effect do not run parallel. The most space consuming fluorophores show the smallest inhibition of the platelet aggregation. Best results were obtained with an azulene, acenaphthene or naphthalene moiety between the two basic nitrogen functions.

Anticoagulants↗
PubMed1997

Capillary electrophoresis of pesticides: V. Analysis of pyrethroid insecticides via their hydrolysis products labeled with a fluorescing and UV absorbing tag for laser-induced fluorescence and UV detection.

Some representative standard pyrethroid insecticides, namely permethrin, phenotrin, cypermethrin, sanmarton and fenpropathrin, were subjected to base hydrolysis with the aim of facilitating the indirect determination of these neutral species of low water solubilities by aqueous capillary electrophoresis. This first involved the base fragmentation of the pyrethroids in alcohol buffer (pH 12.0), and then the selective tagging of the carboxylated hydrolytic products with 7-aminonaphthalene-1,3-disulfonic acid (ANDSA) via a condensation reaction in the presence of organic soluble carbodiimide. The tagging of the hydrolytic products with ANDSA imparted each of the derivatives with two strong sulfonic acid groups whose permanent charges were necessary for achieving aqueous capillary electrophoresis. In addition, the labeling with ANDSA allowed the detection of the derivatives at low levels by capillary electrophoresis laser-induced fluorescence. The geometric and optical isomers of the ANDSA derivatives of the pyrethroid hydrolytic products were best separated when using electrolyte systems composed of sodium phosphate buffer, pH 6.5, containing n-octylglucoside chiral surfactant in the presence of small amounts of acetonitrile (e.g., 10% v/v).

Electrophoresis, Capillary↗
PubMed1981

Fluorescent observations on the stress fiber system of neural crest cells after con A treatment. A simple, quick, fluorescent method.

Concanavalin A (Con A), 25 microgram/ml in the tetrameric form, inhibits migration and differentiation of cultured amphibian neural crest. Affected cells loose their angulated morphology and become rounded. A correlation exists between the lectin treatment and the overall cellular and stress fiber morphology. We describe a quick, simple method for disclosing the stress fiber system using fluorescence microscopy after staining with 1% alcoholic eosin.

Ambystoma↗
PubMed1997

Capillary electrophoresis of carboxylated carbohydrates. III. Selective precolumn derivatization of glycosaminoglycan disaccharides with 7-aminonaphthalene-1,3-disulfonic acid fluorescing tag for ultrasensitive laser-induced fluorescence detection.

Eight different glycosaminoglycan-derived disaccharides were selectively labeled via their carboxylic acid group with 7-aminonaphthalene-1,3-disulfonic acid (ANDSA) by a condensation reaction between the amino group of ANDSA and the carboxylic acid group of the saccharides in the presence of water-soluble carbodiimide. This derivatization reaction yielded stable derivatives with percentage yields as high as 97%. The ANDSA disaccharide derivatives were readily detected by on-column laser induced fluorescence (LIF) with a He-Cd laser at 325 nm. With LIF, the limit of detection was at the nanomolar level, three orders of magnitude lower than the limit of detection of underivatized disaccharides in the uv at 231 nm. In addition, due to the presence of two strong sulfonic acid groups in the ANDSA tag, the derivatives were readily separated at acidic pH (i.e., pH 4.0-5.0) using 100 mM sodium acetate buffers as the running electrolytes. The addition of polycationic spermine in small amounts to the running electrolytes provided different selectivity with baseline resolution in the pH range 6.0-7.0, and the excess ANDSA migrated ahead of the ANDSA disaccharides.

2-Naphthylamine↗
PubMed1976

Effects of ATP and magnesium ions on the fluorescence of harmala alkaloids. Restrictions for the use of harmala alkaloids as fluorescent probes for (Na+ + K+)-ATPase.

1. Harmine and harmaline were investigated as potentially useful fluorescent inhibitors of (Na+ + K+) activated ATPase. 29 From spectroscopic measurements both compounds were shown to form 1 : 1 complexes with ATP, the dissociation constants being 0.65 mM and 1.83 mM for harmine and harmaline respectively. Addition of Mg2+ and enzyme further affected these equilibria. 3. Although it was possible to demonstrate a competitive effect of harmine at the sodium-loading site of the enzyme, other inhibitory effects, including inhibitions of ouabain binding and the ouabain-insensitive ATPase were found. 4. It was concluded that the harmala alkaloids can inhibit (Na+ + K+)-activated ATPase in a complex way involving both Na- and ATP-binding sites. This severely limits their usefulness as spectroscopic probes.

Adenosine Triphosphatases↗
PubMed1987

Preparation of fluorescent derivatives of lipases and their use in fluorescence energy transfer studies in hydrocarbon/water interfaces.

Fluorescein isothiocyanate reacted with a chromobacter and pseudomonad lipase to yield mono-substituted, fully active, enzymes. With the carbocyanine dye 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI) in the non-aqueous phase, fluorescence energy transfer was used to follow the lipase and similarly labelled model proteins in and out of the interface in heptane, and heptane/di-O-palmitoyl-rac-glycerol (a substrate analogue), emulsions. Competitive binding, and displacement by other proteins could also be followed.

Bacteria↗
PubMed1988

Fluorescence quenching of fluorescein by R-phycoerythrin. A pitfall in dual fluorescence analysis.

The use of a single laser fluorescence-activated cell sorter (FACS) to analyse cellular subpopulations by immunochemical staining requires an alternative dye to fluorescein with appropriate spectral characteristics. R-phycoerythrin (RPE) is widely employed for this purpose. In this study the ability of RPE to quench the fluorescein emission when both are attached to the same cell has been demonstrated by dual labelling of tonsil lymphocytes with pairs of monoclonal antibodies. Reduction of the fluorescein signal correlated with the amount of RPE attached and the relative intensity of emission from the two fluorochromes. The possible photochemical mechanisms which result in a reduction of the fluorescein signal by RPE are discussed. The inclusion of control tests, in which RPE is omitted, is recommended in order to avoid misinterpretation of the results of subpopulation analysis by single laser FACS - especially when low levels of fluorescein staining are obtained.

Antibodies, Monoclonal↗
PubMed1996

Sequence verification by hybridisation with fluorescent octanucleotides as a first step to a fluorescent sequencing by hybridisation protocol.

Three sets of partly overlapping octanucleotides are 5' labelled with derivates of the fluorescence dyes fluorescein-, coumarine- and rhodamine, respectively. Hybridisation conditions are determined, under which all octanucleotides hybridise correctly against complementary target sequences bound on nylon membranes. Target sequences are three synthetic 48-mer oligonucleotides and herring sperm DNA, a positive control containing almost all possible octanucleotides. None of the octanucleotides hybridised to incorrect target sequences. Analysing these results, a given sequence could be unambiguously verified. A feature critical for the accuracy of the hybridisation is the temperature during the last washing step. This temperature can be estimated using the equation T = 19 - 0.4(G + C) + 0.15(G + C)2. Using octanucleotides labelled with three different colors, three hybridisations can be performed simultaneously.

Animals↗
PubMed1980

Torison dynamics and depolarization of fluorescence of linear macromolecules. II. Fluorescence polarization anisotropy measurements on a clean viral phi 29 DNA.

The decay of the fluorescence polarization anisotropy (FPA) of ethidium bromide bound to DNA has been studied over a range of time-spans from 18 ns to 120 ns with the aid of a picosecond dye laser. These FPA data have been fitted to three different functional forms: (1) the single-exponential-decay-plus-baseline employed by Wahl et al.; (2) the Initial Exponential Decay Zone formula of a recently developed rigid-rod and torsion spring model for the torsion dynamics of DNA; (3) the Intermediate Zone formula of that same model. At any fixed experimental time-span the formulas (2) and (3) provide slightly better fits than formula (1), but cannot be distinguished from each other by reduced chi-squared values alone, However, only the Intermediate Zone formula fits the data from all different time-spans with the same set of physical parameters The parameters determined for formulas (1) and (2) vary with the time-span of the experiment in a characteristic manner that can be rationalized in the event that the FPA actually follows the Intermediate Zone curve. The fact that the torsion dynamics for this DNA is well described by the Intermediate Zone formula discounts the possibility of distinct widely spaced torsion joints in such clean DNAs. We are able to provide the first reliable value for the torsional rigidity of DNA, C = 1.29 +/- 0.10 X 10(-19) dyne cm2 in 0.01 M NaCl at 25 degree C.

Coliphages↗
PubMed2006

Structure elucidation of laser dye coumarin-540A by joint application of X-ray diffraction, X-ray fluorescence, prompt fluorescence, UV and visible spectroscopy.

X-ray, ultraviolet, and visible light induced photophysical changes of coumarin-540A in ethanol have been studied by the joint applications of X-ray, ultraviolet, and visible spectroscopy. Some impurities were found by X-ray fluorescence measurements. During the high power optical pumping, coumarin showed photochemical changes. Photoproduct emission spectra characteristics showed that photoproduct molecules can also be used as a laser dye at a different emission frequency in the ultraviolet region.

Coumarins↗
PubMed1986

Fluorescence polarization spectroscopy and time-resolved fluorescence kinetics of native cancerous and normal rat kidney tissues.

Steady state fluorescence polarization spectra and time-resolved emission decay kinetics have been measured in vitro from malignant and normal rat kidney tissue. The degrees of polarization and emission lifetimes from the cancerous and normal systems are different. The spectroscopic differences are attributed to environmental transformations local to the native flavin and porphyrin fluorophors' binding sites.

Animals↗
PubMed1995

Analytical approach to the recovery of short fluorescence lifetimes from fluorescence decay curves.

Considerable effort in instrument development has made possible detection of picosecond fluorescence lifetimes by time-correlated single-photon counting. In particular, efforts have been made to narrow markedly the instrument response function (IRF). Less attention has been paid to analytical methods, especially to problem of discretization of the convolution integral, on which the detection and quantification of short lifetimes critically depends. We show that better discretization methods can yield acceptable results for short lifetimes even with an IRF several times wider than necessary for the standard discretization based on linear approximation (LA). A general approach to discretization, also suitable for nonexponential models, is developed. The zero-time shift is explicitly included. Using simulations, we compared LA, quadratic, and cubic approximations. The latter two proved much better for detection of short lifetimes and, in that respect, they do not differ except when the zero-time shift exceeds two channels, when one can benefit from using the cubic approximation. We showed that for LA in some cases narrowing the IRF beyond FWHM = 150 ps is actually counterproductive. This is not so for quadratic and cubic approximations, which we recommend for general use.

Kinetics↗
PubMed2001

Complete karyotype characterization of the K562 cell line by combined application of G-banding, multiplex-fluorescence in situ hybridization, fluorescence in situ hybridization, and comparative genomic hybridization.

This study combines conventional cytogenetics, fluorescence in situ hybridization (FISH), multiplex-FISH and comparative genomic hybridization (CGH). In applying this multimodal approach on the human leukemia cell line K562, the chromosome composition was refined in detail and compared with data from the literature. A hypotriploid karyotype with a modal chromosome number of 67, and 21 unique marker chromosomes were identified. The classification of six markers was identical to published data and the composition of five further markers from the literature could be fully clarified for the first time. The composition of another five markers, which have been interpreted in divergent ways in different studies, were elucidated without doubt. Finally, five new markers of our study seem to have no equivalents in former studies, very likely due to limitations of conventional cytogenetics. The combinatory application of complementary techniques as shown in this study will be very useful to provide the basis of a refined genotype analysis on the chromosomal level.

Chromosome Mapping↗
PubMed2001

The use of multicolor fluorescence technologies in the characterization of prostate carcinoma cell lines: a comparison of multiplex fluorescence in situ hybridization and spectral karyotyping data.

Recent studies have identified several chromosome regions that are altered in primary prostate cancer and prostatic carcinoma cell lines. These targeted regions may harbor genes involved in tumor suppression. We used multiplex fluorescence in situ hybridization (M-FISH) to screen for genetic rearrangements in four prostate cancer cell lines, LNCaP, LNCaP.FCG, DU145, and PC3, and compared our results with those recently obtained using spectral karyotyping (SKY). A number of differences was noted between abnormalities characterized by SKY and M-FISH, suggesting variation in karyotype evolution and characterization by these two methodologies. M-FISH analysis showed that hormone-resistant cell lines (DU145 and PC3) contained many genetic alterations (> or =15 per cell), suggesting high levels of genetic instability in hormone-refractory prostate cancer. Most chromosome regions previously implicated in prostate cancer were altered in one or more of these cell lines. Several specific chromosome aberrations were also detected, including a del(4)(p14) and a del(6)(q21) in the hormone-insensitive cell lines, a t(1;15)(p?;q?) in LNCaP, LNCaP, and PC3, and a i(5p) in LNCaP.FCG, DU145, and PC3. These clonal chromosome abnormalities may pinpoint gene loci associated with prostate tumourigenesis, cancer progression, and hormone sensitivity.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed2002

RARA fluorescence in situ hybridization overcomes the drawback of PML/RARA fluorescence in situ hybridization in follow-up of acute promyelocytic leukemia.

Determination of the remission of acute promyelocytic leukemia (APL) after chemotherapy can be difficult because many cases of APL show reverse transcription polymerase chain reaction positivity after consolidation treatment. Moreover, the discrimination of leukemic promyelocytes and regenerating promyelocytes by morphology is sometimes difficult. Although PML/RARA fluorescence in situ hybridization (FISH) can help, the major drawback of FISH is its high false positive rate, which reaches up to 5-10%. We used RARA FISH at the initial diagnosis (16 cases) and follow-up of APL patients (21 cases) with t(15;17), though RARA FISH was originally designed to detect translocations involving the RARA gene rather than t(15;17), and compared the results with those of PML/RARA FISH. A reference range for PML/RARA and RARA FISH was set using 50 normal control specimens. Using a RARA split probe, we were able to lower the reference range for RARA rearrangement down to 1.5%, which is significantly lower than that of PML/RARA (8%). Actually 74.2% (46/62 cases) of cases with positive signals of the PML/RARA rearrangement by the PML/RARA probe, showed absolutely negative results with the RARA split probe. By conducting RARA FISH, we were able to significantly resolve the difficulty in interpreting results around cut-off value in PML/RARA FISH. In conclusion, we believe that once the PML/RARA rearrangement is confirmed either by G-banding or FISH, RARA FISH is more effective than PML/RARA during the follow-up of APL after treatment.

Biomarkers, Tumor↗