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At least 289 records · Page 16Linked to original sources
PubMed1969

Detection of group A streptococci in throat swabs by direct fluorometry.

A direct fluorometric test for the rapid detection of group A streptococci from throat swabs was compared with the microscopic fluorescent-antibody test. Formalinized throat swab cultures (490) were examined by the two methods, and the results agreed on 84% of the specimens. In another comparison, 15-hr broth cultures of 103 freshly taken throat swabs were tested by both methods. Of the specimens tested, 101 (98%) were either positive or negative by both methods. In all cases, the latter results correlated with the demonstration of presence or absence of group A streptococci in the specimens by cultural isolation and precipitin grouping tests. It may be feasible to use the direct fluorometric test in a diagnostic laboratory as described or possibly to adapt it for automatic processing of throat swab cultures.

Bacteriological Techniques↗
PubMed1994

Compensation for changes in tissue light absorption in fluorometry of hypoxic perfused rat hearts.

Fluorescence studies of NADH and various dyes in tissue are complicated by changes in light absorption, causing spurious results. Methods were developed to reduce and compensate for changes in light absorption in perfused rat hearts, subjected to normoxia and hypoxia. Isosbestic wavelengths were determined (i.e., absorption independent of oxygenation) in the whole ventricular wall and in the epicardium using transmitted and reflected light, respectively. Isosbestic wavelengths were found at approximately 385, 427, 455, 510, and 525 nm, similar in the epicardium, throughout the ventricle, in beating and arrested hearts, although the exact wavelengths varied among experiments. Furthermore, absolute light absorption was identical in the epicardium and endocardium. At nonisosbestic wavelengths, the effect of changing light absorption on fluorescence was quantified at various detection wavelengths using a reference dye. New correction methods were also developed and used to correct indo 1 fluorescence ratios for changing absorption so that results were independent of detection wavelengths. These methods can be used to greatly reduce artifacts due to changing tissue light absorption in a variety of fluorescence experiments.

Adaptation, Physiological↗
PubMed1990

Quantitation of total carbon dioxide in nanoliter samples by flow-through fluorometry.

A new ultramicrofluorometric assay for the measurement of picomole amounts of total CO2 is described. The assay is based on a sequence of two linked enzymatic reactions: HCO3 reacts with phosphoenolpyruvate forming oxaloacetate, and oxaloacetate is then converted to malate with associated oxidation of NADH to NAD+. The fluorescence of NADH is measured in a modified ultramicrofluorometer. The HCO3 content of the sample is proportional to the decrease in NADH fluorescence. The method can resolve differences as small as 5.5 pmol total CO2 in 3-nl samples containing 0-160 pmol. The assay is 5- to 10-fold more sensitive than the widely used microcalorimetric assay. The assay can also measure total CO2 in biological samples. The assay will be useful in measuring transepithelial total CO2 transport in short distal nephron segments with low rates of total CO2 transport without resorting to extremely long collection times.

Carbon Dioxide↗
PubMed1998

Time-resolved fluorometry based sandwich hybridisation assay for HLA-DQA1 typing.

A microtitration plate based time-resolved fluorescence (TRF) hybridisation assay was developed for HLA typing utilising biotinylated sequence-specific catching probes and europium (Eu) labelled gene locus-specific detection probe to allow time-resolved fluorometer reading of the reaction. In an application for HLA-DQA typing a 228 base pair long region of the polymorphic exon 2 of DQA1 gene was amplified and the denatured PCR product distributed into streptavidin-coated microtitration wells together with the detection probe and one of the catching probes. After incubation and washes, the enhancement solution was added and specific hybridisation signal detected by measuring the emitted light. A series of 100 isolated genomic DNA samples were studied using biotinylated probes specific for DQA1*01, *0101/0104, *0103/0201/0601, *0201, *03, *0401/0601, *05 and *0502 alleles with results demonstrating the capacity of the test to detect aimed alleles. A series of whole blood spot samples were also studied and the results confirmed the applicability of this modification of the test.

DNA Primers↗
PubMed1992

Detection of dysplasia and carcinoma in situ by ratio fluorometry.

Fluorescence bronchoscopy was performed in 82 volunteers recruited from occupational groups at risk of exposure to asbestos and/or diesel fumes to determine whether differences in tissue autofluorescence between normal and malignant bronchial tissues can be used to improve the sensitivity of standard fiberoptic bronchoscopy in detecting dysplasic and carcinoma in situ (CIS). This study consisted of 25 nonsmokers, 40 exsmokers, and 17 current smokers with mean ages of 52, 55, and 49 yr, respectively. Tissue autofluorescence was induced by a blue light from an He-Cd laser coupled to the illumination channel of the bronchoscope and analyzed by a ratiofluorometer. One or more sites of moderate or severe dysplasia were found in 12% of the exsmokers and current smokers but in none of the nonsmoker volunteers. CIS was found in two of the exsmokers. The sensitivity of fluorescence bronchoscopy (86%) was found to be 50% better than that of conventional white-light bronchoscopy (52%) in detecting dysplasia and CIS. Pre- and post-bronchoscopy sputum cytology failed to detect these precancerous lesions. Our results suggest that fluorescence bronchoscopy may be an important new method that can improve the ability to detect and localize precancerous and/or CIS lesions.

Asbestos↗
PubMed2006

Simultaneous fluorometry and phosphorometry of Langendorff perfused rat heart: ex vivo animal studies.

Fluorescence imaging of intrinsic fluorophores of tissue is a powerful method to assess metabolic changes at the cellular and intracellular levels. At the same time, exogenous phosphorescent probes can be used to accurately measure intravascular tissue oxygenation. Heart failure is the leading cause of death in America. A rat heart can potentially model the human heart to study failures or other abnormalities optically. We report simultaneous fluorescence and phosphorescence measurements performed on a rat heart. We have used two different optical systems to acquire fluorescence signals of flavoprotein and nicotinamide adenine dinucleotide--the two intrinsic fluorophores of mitochondria--and the phosphorescence signal of an intravascular oxygen probe to extract intracellular and intravascular metabolism loads, respectively.

Animals↗
PubMed1992

Quantitative fluorometry of abnormal mouse sperm nuclei.

An extensive quantitative analysis of deformed mouse spermatozoa was undertaken. Improvements over previous studies included the isolation and purification of sperm nuclei, a multifaceted analytical approach using several fluorochromes and the analysis of individual nuclei classified into shape categories. Malformed sperm nuclei in BALB/c mice could not be distinguished from normal ones in terms of total and basic proteins, sulfhydryl and disulfide group concentration, DNA concentration and chromatin organization. The shape of sperm nuclei is therefore probably determined by the manner in which the internal biochemical components are assembled.

Animals↗
PubMedDate not supplied

Comparison by PAM fluorometry of photosynthetic activity of nine marine phytoplankton grown under identical conditions.

The photosynthetic activity of marine phytoplankton from five algal classes (Phaeodactylum tricornutum, Skeletonema costatum, Thalassiosira oceanica, Thalassiosira weissflogii, Dunaliella tertiolecta, Mantoniella squamata, Emiliania huxleyi, Pavlova lutheri and Heterosigma akashiwo) was investigated under identical growth conditions to determine interspecies differences. Primary photochemistry and electron transport capacity of individual species were examined by pulse amplitude-modulated (PAM) fluorescence. Although few differences were found in maximal photosystem II (PSII) photochemical efficiency between various species, large differences were noticed in their PSII-photosystem I (PSI) electron transport activity. We found that species such as T. oceanica and M. squamata have much lower photochemical activity than H. akashiwo. It appeared that processes involved in electron transport activity were more susceptible to change during algal evolution compared with the primary photochemical act close to PSII. Large variations in the nonphotochemical energy dissipation event among species were also observed. Light energy required to saturate photosynthesis was very different between species. We have shown that M. squamata and H. akashiwo required higher light energy (>1300 micromol m(-2) s(-1)) to saturate photosynthesis compared with S. costatum and E. huxleyi (ca 280 micromol m(-2) s(-1)). These differences were interpreted to be the result of variations in the size of light-harvesting complexes associated with PSII. These disparities in photosynthetic activity might modulate algal community structure in the natural environment where light energy is highly variable. Our results suggest that for an accurate evaluation of primary productivity from fluorescence measurements, it is essential to know the species composition of the algal community and the individual photosynthetic capacity related to the major phytoplankton species present in the natural phytoplankton assemblage.

Electron Transport↗
PubMed2005

Comparison of Cd, Cu, and Zn toxic effects on four marine phytoplankton by pulse-amplitude-modulated fluorometry.

The toxic effects of Cd, Cu, and Zn on four different marine phytoplankton, Dunaliella tertiolecta, Prorocentrum minimum, Synechococcus sp., and Thalassiosira weissflogii, were examined by comparing the cell-specific growth rate, pulse-amplitude-modulated (PAM) parameters (maximum photosystem II quantum yield phiM and operational quantum yield phi'M, chlorophyll a content, and cellular metal concentration, over a 96-h period. The calculated no-observed-effect concentration (NOEC) based on both cell-specific growth rate and two PAM parameters (phiM and phi'M) were mostly identical. Thus, these PAM parameters and cell-specific growth rate were comparable in their sensitivities as the biomarkers for trace metal toxicity to marine phytoplankton. The cyanobacteria Synechococcus sp. was the most sensitive species among the four algal species tested because of its higher cell surface to volume ratio. The toxicity of the three tested metals followed the order of Cd > Cu > Zn based on the cellular metal concentration of the four algae at the NOEC. The cellular metal bioaccumulation followed the same Freundlich isotherm for each metal regardless of the algal species, indicating that the metal accumulation was a nonmetabolic process under high ambient metal concentrations and that the cell surface metal binding was comparable among the different species. For all the algae examined in our study, the bioaccumulation potentials of Cu and Zn were similar to each other, while the Cd bioaccumulation was much lower under environmentally realistic metal concentration.

Biomarkers↗
PubMed2005

Simultaneous determination of carvedilol and ampicillin sodium by first-derivative fluorometry in the presence of human serum albumin.

A sensitive and selective method for the simultaneous determination of carvedilol and ampicillin sodium (AS) in the presence of human serum albumin (HSA) is described. The maximum emission wavelengths of carvedilol and AS are at 357 nm and 426 nm with excitation at 254 nm, respectively. The first-derivative peaks of carvedilol and AS were at 337 nm and 398 nm, respectively. The linear-regression equations of the calibration graphs of carvedilol and AS were C = 0.0001H - 0.0063 and C = 1.530H - 43.84; the correlation coefficients were 0.9990 and 0.9986, respectively. The detection limits were 1 ng ml(-1) for carvedilol and 23 microg ml(-1) for AS, respectively. The effects of the pH, the stability of carvedilol and AS and foreign ions on the determination of carvedilol and AS were examined. The recoveries of carvedilol and AS were measured. This method is simple and can be used for the determination of carvedilol and AS in human serum and urine samples with satisfactory results.

Adrenergic beta-Antagonists↗
PubMed1990

Analysis for the molecular motion of phospholipid bilayer with picosecond fluorometry.

The viscosity and the molecular motion of phospholipid molecule in biological and artificial phospholipid bilayers were studied using picosecond fluorescence depolarization method with rod-like fluorophore, DPH. From the relationship between the viscosity in the lipid bilayer and the free space of phospholipid acyl-chain, it is concluded that the viscosity is determined mainly by the range of wobbling motion of the acyl-chain. Motion of polar head group was also measured by the same method with a newly synthesized fluorescent phospholipid, dipalmitoyl-phosphatidyl-umbelliferone. The rate and the range in the motion of head group were faster and larger than those of acyl-chain and gave the viscosity of head group layer to be 0.03 poise, which was about one tenth of that of acyl-chain layer in the liquid crystalline phase. This fact indicates that the head group layer would not resist the lateral diffusion of molecules in membrane and that the lateral diffusion rate of molecules could be estimated from the viscosity in the acyl-chain layer.

1,2-Dipalmitoylphosphatidylcholine↗