Fluoresceinated IgG was injected centrally into the rabbit's cornea and both its rate of loss from the tissue and its rate of spread in the stroma were estimated by objective fluorometry. A new technique for determining the rate of loss was established which required only the measurement of the maximum fluorescence in the tissue. The rate at which freshly formed IgG in the blood would arrive at...

The analysis of the fluorescence decay using discrete exponential components assumes that a small number of species is present. In the absence of a definite kinetic model or when a large number of species is present, the exponential analysis underestimates the uncertainty of the recovered lifetime values. A different approach to determine the lifetime of a population of molecules is the use of ...

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 specime...

A sensitive and selective method for simultaneous determination of carvedilol and dopamine was described. The emission wavelengths of carvedilol and dopamine were at 354 nm and 314 nm with the excitation at 290 nm, respectively. The determination of carvedilol and dopamine by normal fluorometry was difficult because the emission spectra of carvedilol and dopamine were overlapped seriously. The ...

Proton channels have evolved to provide a pH regulatory mechanism, affording the extrusion of protons from the cytoplasm at all membrane potentials. Previous evidence has suggested that channel-mediated acid extrusion could significantly change the local concentration of protons in the vicinity of the channel. In this work, we directly measure the proton depletion caused by activation of Hv1 pr...

Calcium interaction with phospholipid membranes containing phosphatidic acid is studied by multifrequency phase fluorometry, using DPH as fluorescent molecule. DPH decay is analysed by a continuous distribution of lifetimes. The results suggest an increase of membrane heterogeneity at low calcium concentrations, without changes in the polarity of the environment surrounding the probe.

Time-resolved fluorometry was used for the detection of DNA probes labeled directly with europium (Eu3+) chelate. The sensitivity of this nonisotopic hybridization assay was 100 pg of homologous DNA. Equivalent results with reference tests were obtained in the detection of adenoviruses in clinical specimens.

A detailed procedure for the quantitative determination of metanephrine and normetanephrine is given. Epinephrine and norepinephrine are eliminated by selective adsorption on an alumina column. Metanephrine and normetanephrine are isolated with a cation-exchange resin. Fluorescence is developed by a two-step ferricyanide oxidation at two different pH values followed by tautomerization. The conc...