Measurement of Fluorescein and Fluorescein Monoglucuronide in the Living Human Eye

Fluorescein monoglucuronide is a fluorescent metabolite of fluorescein, and is '/»to V34 as fluorescent as fluorescein, depending on the wavelength of excitation. After systemic administration, fluorescein glucuronide reaches concentrations many times greater than fluorescein. In order to study the effect of fluorescein glucuronide on the measurement of ocular dynamics, we devised a technique to measure fluorescein and fluorescein glucuronide in the anterior segment of the living human eye. Concentrations of each fluorophore were determined by differential spectrofluorophotometry from measurements at excitation wavelengths of 457.9 nm and 488.0 nm. Measurements were made on normal volunteers after oral and intravenous administration of fluorescein. Fluorescein was the dominant fluorophore during the first hour, while fluorescein glucuronide became dominant after 3 hours. By 6 hours there was 10 to 30 times more fluorescein glucuronide than fluorescein in the anterior chamber after oral administration, and three to ten times more after intravenous administration. The blood aqueous diffusion coefficient k<\ estimated from the apparent concentration of fluorescein measured at 457.9 nm was consistently greater than k<j estimated from measurements at 488.0 nm. Estimates of k<j, which were made on the basis of concentrations of fluorescein determined from measurements at both wavelengths, were lower than estimates based on measurements at either wavelength. These results indicate that wavelength of excitation may influence the determination of ocular parameters when systemic fluorescein is used. Care must be taken in the interpretation of measurements when metabolites of a fluorophore can interfere with measurement of the fluorophore itself. Invest Ophthalmol Vis Sci 27: [966][967][968][969][970][971][972][973][974] 1986 When fluorescein is given systemically, it is rapidly metabolized to other compounds. 1 " 4 Three of these metabolites have been examined and characterized by Chen et al. 1 ' 2 The metabolite of most importance in ocular fluorophotometry is fluorescein monoglucuronide (FG), since it is highly fluorescent, although not as fluorescent as fluorescein, and it appears in relatively high concentration. In the blood, concentrations of FG are several times greater than concentrations of fluorescein several hours after oral or intravenous administration of fluorescein. 5 A significant portion of the fluorescence measured from the plasma after a systemic dose of fluorescein may originate from FG because of its fluorescence and relative abundance. It is not clear how much FG crosses the blood-ocular barrier in the vitreous body or anterior segment. One might expect that, due to its lower lipid solubility, 5 it might cross the blood-ocular barrier less freely than fluorescein. On the other hand, since there is a high molar ratio of FG to fluorescein in the blood after a systemic dose, there may be a greater difference in concentration of FG across the blood-ocular barrier. The extent to which FG contributes to ocular fluorescence after a systemic dose is unknown. The concentration of FG in a solution can be determined by measuring fluorescence before and after breakdown with /3-glucuronidase. 1 ' 2 This technique is well suited for measuring FG in blood and urine, but for obvious reasons is not suited for measuring ocular concentrations of FG in human subjects. A noninvasive technique would be preferable, such as that proposed by Grotte and his associates, 5 which utilizes differential spectrofluorophotometry. This technique makes use of differences in excitation spectra of fluorescein and FG. Excitation of both fluorophores peaks near 495 nm. At this wavelength at pH 7.3, the molar fluorescent intensity of fluorescein is about 34 times that of FG. 5 Excitation of fluorescein decreases rapidly at shorter wavelengths, while excitation of FG decreases more gradually. At 445 nm this ratio is only about 5. Because of these spectral differences, the extent to which FG contributes to fluorescence measured from a mixed solution of the two fluorophores is greatly dependent upon wavelength of excitation. 96

Latrunculins’ effects on intraocular pressure, aqueous humor flow

PURPOSE. To determine the effects of latrunculin (LAT)-A or -B on intraocular pressure (IOP), aqueous humor flow (AHF), anterior chamber (AC) protein concentration ([protein] AC ), corneal endothelial permeability and morphology, and corneal thickness in living cynomolgus monkeys. METHODS. Topical LAT-A or LAT-B was administered to one eye, and vehicle to the other. IOP was measured by Goldmann tonometry, AHF and corneal endothelium transfer coefficient (k a ) by fluorophotometry, [protein] AC by Lowry assay, corneal endothelial cell morphology by specular microphotography, and corneal thickness by ultrasound pachymetry. RESULTS. LAT-A began to lower IOP at 6 hours and maximally reduced IOP by 4.6 mm Hg at 9 hours. LAT-B lowered IOP within 1 hour and maximally reduced IOP by 3.1 mm Hg at 6 hours. LAT-A increased AHF by 87% for 3 hours and increased k a by 94% over 6 hours; LAT-B increased k a by 39% over 6 hours without affecting AHF. LAT-A increased IV fluorescein entry into the cornea approximately 10 fold, but did not affect IV fluorescein entry into the AC. LAT-A increased [protein] AC by 25% at 2 hours but not 5.5 hours. LAT-B variably and insignificantly increased [protein] AC at 1 hour but not at 6.5 hours. LAT-A induced extensive corneal endothelial pseudoguttata within 1 hour, with normal cell counts by 7 days. LAT-B increased central corneal thickness maximally by 47 m at 3.5 hours. CONCLUSIONS. LAT-A and -B significantly reduced IOP and were consistent in their facility-increasing effect, indicating that pharmacologic disorganization of the actin cytoskeleton in the trabecular meshwork by latrunculins may be a useful antiglaucoma strategy. However, effects on corneal endothelium or ciliary epithelium are a potential safety issue. (Invest Ophthalmol Vis Sci. 2000;41: 1749 -1758 L atrunculins, macrolides isolated from the marine sponge Latrunculia magnifica, are specific, and potent actindisrupting agents that sequester monomeric G-actin, leading to the disassembly of actin filaments

The Atacama Cosmology Telescope: Cosmological parameters from three seasons of data

We present constraints on cosmological and astrophysical parameters from high-resolution microwave background maps at 148 GHz and 218 GHz made by the Atacama Cosmology Telescope (ACT) in three seasons of observations from 2008 to 2010. A model of primary cosmological and secondary foreground parameters is fit to the map power spectra and lensing deflection power spectrum, including contributions from both the thermal Sunyaev-Zeldovich (tSZ) effect and the kinematic Sunyaev-Zeldovich (kSZ) effect, Poisson and correlated anisotropy from unresolved infrared sources, radio sources, and the correlation between the tSZ effect and infrared sources. The power ell^2 C_ell/2pi of the thermal SZ power spectrum at 148 GHz is measured to be 3.4 +\- 1.4 muK^2 at ell=3000, while the corresponding amplitude of the kinematic SZ power spectrum has a 95% confidence level upper limit of 8.6 muK^2. Combining ACT power spectra with the WMAP 7-year temperature and polarization power spectra, we find excellent consistency with the LCDM model. We constrain the number of effective relativistic degrees of freedom in the early universe to be Neff=2.79 +\- 0.56, in agreement with the canonical value of Neff=3.046 for three massless neutrinos. We constrain the sum of the neutrino masses to be Sigma m_nu < 0.39 eV at 95% confidence when combining ACT and WMAP 7-year data with BAO and Hubble constant measurements. We constrain the amount of primordial helium to be Yp = 0.225 +\- 0.034, and measure no variation in the fine structure constant alpha since recombination, with alpha/alpha0 = 1.004 +/- 0.005. We also find no evidence for any running of the scalar spectral index, dns/dlnk = -0.004 +\- 0.012.Comment: 26 pages, 22 figures. This paper is a companion to Das et al. (2013) and Dunkley et al. (2013). Matches published JCAP versio

Loudness and acoustic parameters of popular children's toys

ObjectiveThis project was conducted to evaluate the loudness and acoustic parameters of toys designed for children. In addition, we investigated whether occluding the toys' speaker with tape would result in a significant loudness reduction; thereby potentially reducing the risk of noise induced hearing loss.MethodsTwenty-six toys were selected after an initial screening at two national retailers. Noise amplitudes at 0.25, 0.5, 1, 2, 4, and 8kHz were measured using a digital sound level meter at a distance of 0 and 30cm. The toys' speakers were then occluded using adhesive tape and the same acoustic parameters were re-measured.ResultsMean maximum noise amplitude of the toys at 0cm and 30cm was 104dBA (range, 97-125dBA) and 76dBA (range, 67-86dBA), respectively. Mean maximum noise amplitude after occlusion at 0cm and 30cm distances was 88dBA (range, 73-110dBA) and 66dBA (range, 55-82dBA), respectively, with a p-value &lt;0.001.ConclusionsProper use of the loudest toys at a distant of 30cm between the speaker and the child's ear will likely not pose a risk of noise-induced hearing loss. However, since most toys are used at closer distances, use of adhesive tape is recommended as an effective modification to decrease the risk of hearing loss

Standardization of Corneal Haze Measurement in Confocal Microscopy

This paper describes standardization of corneal haze as measured by clinical confocal microscopy. Standardization allows investigators to compare measurements in longitudinal studies and across laboratories