Transport fluorescein

To visualize the iontophoretic transport pathways of fluorescein across mammalian skin, Burnette and Ongpipattanakul [61] positioned an optical microscope on the receiver (dermal) side of excised human skin and iontophoresed the fluorophore. Discrete, localized sites of fluorescein transport were visualized (see Fig. 6). A set of microelectrodes were then rastered across the visualized pathways and the corresponding voltage gradient was measured. For each of the resistance measurements, the maximum potential difference detected was directly over the center of the visualized pathways, verifying that the discrete sites of fluorescein transport did, indeed, correspond to sites of... 

Masereeuw R, vandenBergh EJ, Bindels RJ. Characterization of fluorescein transport in isolated proximal tubular cells of the rat evidence for mitochondrial accumulation. J Pharmacol ExpTher 1994 269 1261-1267. 

FIGURE 20.6 (a) A backscattering electron (BSE) image of a nanoporous membrane after it was soaked with GNPs. EDX data are shown in the inset of this figure, (b) A plot of absorbance at 490 nm of fluorescein versus time (min) for fluorescein transport through stretched (circle), unstretched (triangle), and an unstretched with no pores (square) PDMS membranes, respectively. (From Jiao, K. et al., J. Membr. Sci., 401, 25, 2012. With permission.)... 

Chemical modification studies with fluorescein-5 -isothiocyanate support the proximity of Lys515 to the ATP binding site [98,113-117,212,339]. Fluorescein-5 -isothiocyanate stoichiometrically reacts with the Ca -ATPase in intact or solubilized sarcoplasmic reticulum at a mildly alkaline pH, causing inhibition of ATPase activity, ATP-dependent Ca transport, and the phosphorylation of the Ca " -ATPase by ATP the Ca uptake energized by acetylphosphate, carbamylphos-phate or j -nitrophenyl phosphate is only partially inhibited [113,114,212,339]. The reaction of -ATPase with FITC is competitively inhibited by ATP, AMPPNP, TNP-ATP, and less effectively by ADP or ITP the concentrations of the various nucleotides required for protection are consistent with their affinities for the ATP binding site of the Ca -ATPase [114,212,340]. 

N., Horie, T., Characteristics of transport of fluoresceinated methotrexate in rat small intestine, Life Sci. 2001, 69, 739-747. 

Sun H, Johnson DR, Finch RA, Sartorelli AC, Miller DW, Elmquist WF. Transport of fluorescein in MDCKII-MRP1 transfected cells and mrpl-knock-out mice. Biochem Biophys Res Com-mun 2001 284(4) 863-869. 

Hoogstraate AJ, Cullander C, Nagelkerke JF, Senel S, Verhoef JC, Junginger HE, Bodde HE (1994) Diffusion rates and transport pathways of fluorescein isothiocyanate (FITC)-labeled model compounds through buccal epithelium. Pharm Res 11 83-89... 

An alternative method for assessing cell layer integrity is through the use of hydrophilic paracellular transport markers (e.g., radiolabeled D-mannitol or fluorescein-Na+), which passively traverse cells by the paracellular route. Small amounts of compound required for in vitro conjunctival cell culture transport experiments make this approach well suited for screening purposes. Relative absorption index of a series of pharmacologically active molecules can be ranked against known markers for the identification of candidates with potential absorption problems, which is a reliable tool to select drug candidates with optimal characteristics. 

C. B. Engler, B. Sander, M. Larsen, P. Koefoed, H. H. Parving, and H. Lund-Andersen. Probenecid inhibition of the outward transport of fluorescein across the human blood-retina barrier. Acta Ophthalmol. 72 663-667 (1994). 

Buolamwini JK, Craik JD, Wiley JS, Robins MJ, Gati WP, et al. 1994. Conjugates of fluorescein and SAENTA (5 -S-(2-ami-noethyl)-N -(4-nitrobenzyl)-5 -thioadenosine) flow cytometry probes for the es nucleoside transporter elements of the plasma membrane. Nucleosides Nucleotides 13 737-751. 

Gati WP, Paterson ARP, Larratt LM, Turner AR, Belch AR 1997. Sensitivity of acute leukemia cells to cytarabine is a correlate of cellular es nucleoside transporter site content measured by flow cytometry with SAENTA-fluorescein. Blood 90 346-53. 

The research group led by Dr. Djilali at the University of Victoria has developed an ex situ experimental technique using fluorescent microscopy to study the liquid water transport mechanisms inside diffusion layers and on their surfaces [239-243]. The diffusion layer is usually placed between two plates (the top plate may or may not have a channel) the liquid water, which is pumped through a syringe pump, flows from the bottom plate through the DL. Fluorescein dye is added to the water for detection with the microscope. 

A series of analogs with probes of varying size and polarity was prepared to determine the effect on siderophore receptor transport. These include 7-nitrobenz-2-oxa-l,3-diazole (NBD) (176-179), fluorescein-5-isothiocyanate methyl ether methyl ester (diMe-FITC)... 

The emission of fluorescein is strongly self-quenched at higher concentrations (> 10-4 M) of the dye. Thus the yellow-green fluorescence gives way to a dull orange solution at high concentrations. Transport of solutes across a membrane is accompanied by a change in volume. Thus Chen et al. [34] and... 

Techniques which allow one to monitor the boundary layer as a function of time, such as total internal reflection fluorescence (TIRF) spectroscopy 4 43), permit a quantitative evaluation of interfacial mass transport processes using, for example, fluorescently-tagged macromolecules which do not adsorb, such as fluorescein-labeled dextran 40 ... 

Konishi Y, Hagiwara K, Shimizu M. 2002. Transepithelial transport of fluorescein in Caco-2 cell monolayers and use of such transport in in vitro evaluation of phenolic acid availability. Biosci Biotechnol Biochem 66 2449-2457. 

Kuwayama K, Miyauchi S, Tateoka R, Abe H, Kamo N. 2002. Fluorescein uptake by a monocarboxylic acid transporter in human intestinal Caco-2 cells. Biochem Pharmacol 63 81-88. 

At the inner border of ONH, the ILM becomes continuous with the basement membrane of fibrous astrocytes lining the internal surface of the ONH [21]. However, the lateral borders between the ONH and the adjacent choroid and retina are not well defined. Furthermore, it was reported [49] that micro vessels in the prelaminar region of the ONH lack classical blood-brain barrier characteristics and display nonspecific permeability, possibly mediated by vesicular transport. Thus, there is a theoretical possibility that topically applied drugs can penetrate indirectly through the retrobulbar space and then, through the ONH, reach the posterior choroid and retina. It was reported that following retrobulbar administration of fluorescein, the dye rapidly accumulated in the ONH and penetrated later to the vitreous [50],... 

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