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At least 469 records · Page 26Linked to original sources
PubMed1999

Simultaneous indocyanine green and fluorescein angiography in retinal pigment epithelium tear using the confocal scanning laser ophthalmoscope.

PURPOSE: To describe the indocyanine green angiographic pattern of retinal pigment epithelium tears in the setting of age-related macular degeneration compared with the fluorescein angiographic features. METHODS: Twelve consecutive patients (12 eyes) with a retinal pigment epithelium tear underwent simultaneous indocyanine green angiography and fluorescein angiography with the confocal scanning laser ophthalmoscope. The findings for the two modes were compared. RESULTS: Choroidal neovascular membrane was evident beneath the rolled retinal pigment epithelium on indocyanine green angiograms in 11(92%) of 12 eyes: a focal neovascular membrane was apparent in five (42%) of 12 eyes, whereas a plaque neovascular membrane was seen in six (50%) of 12 eyes. In comparison, fluorescein angiography demonstrated late leakage as a result of occult choroidal neovascular membrane in nine (82%) of 11 eyes but no well-defined choroidal neovascular membrane. CONCLUSIONS: Indocyanine green angiography is superior to fluorescein angiography for imaging choroidal neovascularization in cases of retinal pigment epithelium tear and may serve as an important adjunct to indocyanine green-guided laser treatment in selected cases.

Aged↗
PubMed2000

Comparison of fluorescein angiography and indocyanine green angiography for imaging of choroidal neovascularization in hemorrhagic age-related macular degeneration.

PURPOSE: To compare fluorescein angiography and indocyanine green angiography for imaging of choroidal neovascularization located under subretinal hemorrhage, in age-related macular degeneration. METHODS: In a retrospective study, 30 eyes of 30 consecutive patients with hemorrhagic age-related macular degeneration were evaluated with fluorescein angiography and indocyanine green angiography. In each eye, areas of macular hemorrhage, choroidal neovascularization, and total lesion (hemorrhage plus choroidal neovascularization) were measured, and the choroidal neovascularization was categorized as classic, occult, or mixed on fluorescein angiography, and as hot spot, plaque, or combined lesion on indocyanine green angiography. Results of the two techniques were compared for the ability to identify a laser-treatable lesion. RESULTS: Fluorescein angiography showed fluorescence in most cases (28, 93.3%). In 23 cases (76.6%), the fluorescence pattern was compatible with occult choroidal neovascularization. Indocyanine green angiography revealed defined patterns of fluorescence in 27 cases (90%): 12 hot spots, seven plaques, and eight combined hot spots and plaques. Twenty lesions (66.6%) detected by indocyanine green angiography were considered eligible for laser therapy. Nine of them (45%) were extrafoveal. CONCLUSIONS: Indocyanine green angiography is beneficial for imaging choroidal neovascularization located under subretinal hemorrhage. Choroidal neovascularization demonstrated on indocyanine green angiography may be considered eligible for laser treatment. Therefore, indocyanine green angiography should be considered in cases of hemorrhagic age-related macular degeneration.

Choroid↗
PubMed1994

High resolution structures of the 4-4-20 Fab-fluorescein complex in two solvent systems: effects of solvent on structure and antigen-binding affinity.

Three-dimensional structures were determined for three crystal forms of the antigen binding fragment (Fab) of anti-fluorescein antibody 4-4-20 in complex with fluorescein. These included 1) a triclinic (P1) form crystallized in 47% (v/v) 2-methyl-2,4-pentanediol (MPD); 2) a triclinic (P1) form crystallized in 16% (w/v) poly(ethylene glycol), molecular weight 3350 (PEG); and 3) a monoclinic (P21) form crystallized in 16% PEG. Solvent molecules were added to the three models and the structures were refined to their diffraction limits (1.75-A, 1.78-A, and 2.49-A resolution for the MPD, triclinic PEG, and monoclinic PEG forms, respectively). Comparisons of these structures were interesting because 4-4-20 exhibited a lower antigen-binding affinity in 47% MPD (Ka = 1.3 x 10(8) M-1) than in either 16% PEG (Ka = 2.9 x 10(9) M-1) or phosphate-buffered saline (Ka = 1.8 x 10(10) M-1). Even though the solution behavior of the antibody was significantly different in MPD and PEG, the crystal structures were remarkably similar. In all three structures, the fluorescein-combining site was an aromatic slot formed by tyrosines L32, H96, and H97 and tryptophans L96 and H33. In addition, several active site constituents formed an electrostatic network with the ligand. These included a salt link between arginine L34 and one of fluorescein's enolate oxygen atoms, a hydrogen bond between histidine L27d and the second enolic group, a hydrogen bond between tyrosine L32 and the phenylcarboxylate group, and two medium range (approximately 5 A) electrostatic interactions with lysine L50 and arginine H52. The only major difference between the triclinic MPD and PEG structures was the degree of hydration of the antigen-combining site. Three water molecules participated in the above electrostatic network in the MPD structure, while eight were involved in the PEG structure. Based on this observation, we believe that 4-4-20 exhibits a lower affinity in MPD due to the depletion of the hydration shell of the antigen-combining site.

Amino Acid Sequence↗
PubMed2003

Idiopathic epiretinal membranes: cell type, growth factor expression, and fluorescein angiographic and retinal photographic correlations.

BACKGROUND: We studied the cellular constituents and the expression of vascular endothelial growth factor (VEGF) and transforming growth factor-beta (TGF-beta2) in idiopathic epiretinal membranes (ERMs), attempting to correlate the presence of these growth factors with fluorescein leakage during angiography and with the amount of macular scar tissue. METHODS: Idiopathic ERMs were excised at vitrectomy in 41 consecutive cases and stained for glial fibrillary acidic protein (GFAP), vimentin, cytokeratin, desmin and actin. A subset of 13 cases for which fluorescein angiograms and colour retinal photographs were available was further studied for the presence of VEGF and TGF-beta2 in the ERMs, fluorescein leakage and amount of macular scar tissue. RESULTS: Of the 41 ERMs, 31 (76%) were found to be fibroglial by light microscopy; 40 (98%) stained for GFAP, 39 (95%) for vimentin, 10 (24%) for cytokeratin, 3 (7%) for desmin and 11 (27%) for actin. Of the 13 ERMs in the subset, staining was positive for VEGF in 11 (85%) and for TGF-beta2 in 11 (85%). There was no statistically significant relationship between the presence of VEGF and leakage (p = 0.68) or between the presence of TGF-beta2 and scar size (p = 0.90). When both VEGF and TGF-beta2 were present, there was likely to be leakage or a large scar, or both, which suggested that an interaction exists between the two growth factors (p = 0.057). When leakage occurred, large scars were 2.5 times less likely to be present; when no leakage occurred, large scars were 2.5 times more likely to be present (odds ratio 0.4; Yules association coefficient -0.43). INTERPRETATION: The cells constituting idiopathic ERMs were primarily fibroglial with minimal staining evidence for the presence of contractile proteins in their cytoplasm. VEGF and TGF-beta2 were present in 85% of specimens. Although there was no direct correlation between the presence of these growth factors and either fluorescein leakage or the abundance of scar tissue respectively, there was some evidence for the interaction of these growth factors in producing either leakage or abundance of scar tissue.

Capillary Permeability↗
PubMedDate not supplied

Fluorescein and indocyanine green videoangiography of choroidal melanomas.

PURPOSE: This study was performed to determine what role indocyanine green video angiography might play in the evaluation of choroidal melanomas, and to compare this role with that of fluorescein angiography. METHODS: Six patients with posterior segment uveal melanoma underwent digital fluorescein and indocyanine green videoangiography. All patients were women and their mean age was 50.7 years. RESULTS: In all eyes with melanoma, fluorescein angiography revealed irregular hyperfluorescence in the early phase and staining of the tumor in the late phase. A double circulation pattern was obvious in 1 eye with a mushroom-shaped melanoma. The patterns of indocyanine green videoangiography varied, depending on the degree of tumor pigmentation, thickness, and vascularity. Early frames of indocyanine green video angiography demonstrated hypofluorescence in all eyes, and the intrinsic choroidal vasculature was obvious in 3 eyes. In the late phase of indocyanine green videoangiograms, different patterns (hyperfluorescence, three-ring pattern) were observed. CONCLUSION: Indocyanine green videoangiography may be a useful adjunct to fluorescein angiography in the evaluation of choroidal melanomas.

Adult↗
PubMed1982

Fluorescein dilaurate--tubeless test for pancreatic exocrine failure.

The usefulness of fluorescein dilaurate as an indicator of pancreatic exocrine failure has been assessed in 70 patients and normal volunteers. The test consisted of a comparison of urinary fluorescein excretion after ingestion of fluorescein dilaurate with that after ingestion of unesterified fluorescein. The test was easy to perform and acceptable to the patients. The sensitivity of the test was 95%. There was a false-positive rate of 11% in a group of patients who had steatorrhoea which was non-pancreatic in origin. The test can be a useful screening test for the exclusion of pancreatic exocrine failure as a cause of steatorrhoea and can be conducted in outpatients.

Celiac Disease↗
PubMed1998

Effects of secondary forces on a high affinity monoclonal IgM anti-fluorescein antibody possessing cryoglobulin and other cross-reactive properties.

The effects of secondary forces on monoclonal IgM anti-fluorescein antibody 18-2-3 reactivity were investigated and the results correlated with similar studies characterizing anti-fluorescein mAbs 4-4-20 and 9-40. mAb 18-2-3 was considered an important model for further elucidation of secondary forces since it possessed ligand binding properties similar to mAb 4-4-20, such as a similar affinity, but due to a very different primary structure it was idiotypically and metatypically distinct. mAb 18-2-3 also possessed cryoglobulin (anti-Ig) and extensive cross-reactive properties (e.g. anti-phenyloxazolone) suggestive of an atypical anti-fluorescein active site. The reactivity of mAb 18-2-3 with model fluorescein-peptides was modulated by secondary forces in a manner that differed from both mAbs 4-4-20 and 9-40. Thus, the effects of secondary forces seemed to vary with each monoclonal antibody even though each of the immunoglobulins studied were specific for the same homologous ligand. Results indicated that secondary forces impacted immune complex stability, variable domain conformation and protein dynamics. Models were postulated to account for secondary effects on the mAb 18-2-3 active site relative to mAbs 4-4-20 and 9-40. Levels of hydration, active site architecture and local amino acid dynamics were among the models cited.

Animals↗
PubMed1979

Fluorescein angiography in retrolental fibroplasia: experience from 1969-1977.

Acute proliferative retrolental fibroplasia (RLF) has been studied in premature infants employing a Zeiss fundus camera and fluorescein angiography. A total of 164 angiograms have been performed on 122 infants. At the present time, angiography is reserved for studying infants with peculiar or puzzling fundus pictures. A dose of 0.1-0.4 cc of 10% sodium fluoresceinate is employed, depending on the age and the weight of the baby. Fluorescein clearly outlines the major arteriovenous shunt in the retina, which is the hallmark of acute RLF. The shunt fills with fluorescein and leaks it profusely. On regression, a fine brush border of capillaries is seen in the region where the shunt previously had been located. Study of the population susceptible to RLF reveals it to be the smallest sickest babies in the premature nursery.

Female↗
PubMed1985

Measurement of fluorescein angiograms of the optic disc and retina using computerized image analysis.

Computerized image analysis was used to quantify objectively fluorescein angiograms of the optic disc, peripapillary choroid, and retina. Techniques were developed to measure fluorescein filling rates of the optic disc and the retinal vessels and the area of fluorescein filling defects within the optic disc. Two subjects, one with glaucoma and the other with ocular hypertension, showed increases of areas of fluorescein filling defects of the optic disc on follow-up and are presented here as examples of the application of these techniques. This methodology can be applied to the longitudinal follow-up of individual patients with glaucoma and retinal diseases, as well as to cross-sectional studies of patient populations.

Adolescent↗
PubMed1987

Increase of pallor and fluorescein-filling defects of the optic disc in the follow-up of ocular hypertensives measured by computerized image analysis.

In 24 ocular hypertensive patients, two optic disc fluorescein angiograms were obtained a mean of 3.9 years apart. Using computerized image analysis, we measured the area of pallor and the fluorescein-filling defect area within the disc and the fluorescein circulation parameters representing the filling rates of optic disc, choroid, and retinal vessels. The results indicated that increase in pallor and fluorescein-filling defect areas, as well as a slowed filling rate of the retinal veins, correlated with glaucomatous progression.

Aged↗
PubMed1991

Effect of contact lens biomicroscopy on the clarity of fluorescein angiography.

To study the effect of contact lens fundus biomicroscopy on the clarity of subsequent fluorescein angiography, the authors compared the fluorescein angiogram from 20 eyes recently examined using a fundus contact lens with fellow control eyes. Saline solution was used to couple the lens to the cornea. In 15 (75%) of the 20 pairs of eyes studied, there was no difference in the fluorescein angiogram clarity between examined and control eyes. In five (25%) patients, there was a slight asymmetry in clarity between the examined and control eyes, but this did not affect the ability to interpret the angiogram. The results were verified by comparing the overall quality of the transit phase of the angiograms. The application of a fundus contact lens to the cornea using saline solution as a coupling agent does not adversely affect the clarity of subsequent fluorescein angiography.

Contact Lenses↗
PubMed1995

Fundus photographic and fluorescein angiographic characteristics of pseudoholes of the macula in eyes with epiretinal membranes.

BACKGROUND: The fluorescein angiographic characteristics in eyes with pseudoholes of the macula associated with epiretinal membranes have not been studied extensively. METHODS: Stereo photographs and fluorescein angiograms from 83 consecutive eyes of 80 patients with pseudoholes of the macula were evaluated by two independent graders for epiretinal membrane opacity, fluorescence in the base of the pseudohole, and late perifoveal pooling of dye. RESULTS: Hyperfluorescence in synchrony with choroidal fluorescence appeared within the base of the pseudohole in 52 (63%) of the 83 eyes studied. The hyperfluorescence was smaller than the pseudohole in 37 (45%) eyes. Diffuse hyperfluorescence filled the pseudohole in 15 (18%) eyes. No fluorescence was seen in 20 (24%) eyes. Eleven (13%) eyes could not be graded due to coexistent macular disease or media opacity. Fluorescence within the area of pseudohole was less common in eyes with opaque epiretinal membranes than in eyes with visible or transparent epiretinal membranes (P = 0.002). Fluorescence within the area of the pseudohole was also less common in eyes with evidence of macular edema on fluorescein angiography (P < 0.001). The mean visual acuity was better for eyes with hyperfluorescence within the area of the pseudohole than for eyes without hyperfluorescence (P < 0.01). CONCLUSION: A common fluorescein angiographic characteristic associated with pseudoholes of the macula is early hyperfluorescence within the area of the pseudohole. This hyperfluorescence coincides with choroidal filling and appears to be a form of transmission defect rather than a blocking of surrounding choroidal fluorescence by the epiretinal membrane. This central hyperfluorescence may result in misdiagnosis of the macular pseudohole as a full-thickness macular hole.

Basement Membrane↗
PubMed1997

Synthesis, physical and biological properties of lithocholyl-lysyl-fluorescein: a fluorescent monohydroxy bile salt analogue with cholestatic properties.

We have synthesised and characterised a fluorescent monohydroxy bile salt analogue, lithocholyl-lysyl-fluorescein and compared its physical and biological properties with those of lithocholate, glycolithocholate, sulpholithocholate, lithocholic acid glucuronide and taurocholate. The synthetic method used excess N-epsilon-CBZ-L-lysine methyl ester hydrochloride and lithocholic acid via N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinolone (EEDQ) to give lithocholyl-lysine. Lithocholyl-lysyl-fluorescein (LLF) was then prepared using equimolar amounts of lithocholyl-lysine and fluorescein isothiocyanate (FITC) in bicarbonate buffer. LLF retained an apple green fluorescence, similar to that of fluorescein. Unlike lithocholate, the critical micellar concentrations (CMCs) of LLF, glycolithocholate (GLC), lithocholic acid glucuronide (LG) and sulpholithocholic acid (SLC) were similar. HPLC retention times (tRs) of LLF and GLC were similar with a ratio of LLF/GLC of 1.05. In contrast, the tR of SLC (6.52 min) but not of LG (21.2 min) was more comparable to that of taurocholate (5.73 min). In rats under pentobarbital anaesthesia, the plasma half-life (t(1/2alpha)) (min) was 4.5 +/- 1.3 (n = 6) for LLF, 2.9 +/- 0.4 (n = 5) for [14C]sulpholithocholate (14C-SLC) and 4.3 +/- 0.3 (min) for [14C]lithocholic acid glucuronide (14C-LG). Plasma clearances of 14C-SLC, LLF and 14C-LG were 15.5 +/- 2.2 (n = 6), 18.1 +/- 4.2 (n = 6) and 17.8 +/- 0.5 ml/min/kg (n = 6) (P = 0.15), respectively. Biliary excretion in bile-fistula rats gave cumulative 20 min biliary output as a percentage of injected dose as follows: LLF, 71.6 +/- 0.8% (n = 10); 14C-SLC, 75.5 +/- 2.8% (n = 6) and 14C-LG, 61.7 +/- 0.5% (n = 6) (P = NS). Peak biliary excretion rates, given as % dose/2 min, were 10.2 +/- 0.3 for LLF, 13.5 +/- 0.6 for 14C-SLC and 12.8 +/- 0.4 for 14C-LG. In another group of bile-fistula rats, a 3.0 micromol/500 microl saline i.v. bolus of LLF caused a 15.4 +/- 1.9% decrease in bile flow and, similarly, sodium lithocholate in a solution of albumin caused a 17.9 +/- 1.8% (P = NS) diminution in bile flow. Despite the similar cholestatic properties of LLF and lithocholate, LLF was more soluble than lithocholate, with a relative retention time on HPLC similar to that of GLC. LLF is a divalent 'unipolar' anionic fluorescent monohydroxy bile salt analogue with physical, biological and cholestatic properties that are similar to those of lithocholate, glycolithocholate and their derivatives and thus offers a potentially useful probe for studying mechanisms of monohydroxy bile salt-induced cholestasis at the hepatocellular level.

Animals↗
PubMed1998

Dynamics of the Lens culinaris agglutinin-lactotransferrin and serotransferrin complexes, followed by fluorescence intensity quenching of fluorescein (FITC) with iodide and temperature.

Dynamics of the fluorescent Lens culinaris agglutinin-fluorescein complex (LCA-FITC) are studied in absence and in presence of two glycoproteins, lactotransferrin (LTF) and serotransferrin (STF). Glycans of the serotransferrin are not fucosylated, while those of the lactotransferrin have an alpha-1,6-fucose bound to the N-acetylglucosamine residue linked to the peptide chain, and an alpha-1,3-fucose bound to the N-acetyllactosamine residues. Interaction between the lectin and the two glycoproteins occurs via the carbohydrate residues. Affinity between LCA and LTF is 50 times higher than that between LCA and STF, as a result of the alpha-1, 6-fucose-LCA linkage. In the present work, we studied the effect of the tight bond between the alpha-1,6-fucose and LCA on the dynamics of the amino acids of the lectin, by fluorescence intensity quenching with iodide and by thermal intensity quenching. Fluorescence intensity quenching with iodide indicates that the bimolecular diffusion constant of iodide is 2.402+/-0.068x109 and 1. 160+/-0.090x109 M-1 s-1, when the interaction occurs with free fluorescein and with fluorescein bound to LCA, respectively. Binding of STF or LTF to the LCA-FITC complex yields a bimolecular diffusion constant of 1.675+/-0.06x109 and 1.155+/-0.087x109 M-1 s-1, respectively. Thermal intensity quenching does not occur for fluorescein free in solution while it is linear with temperature with a relative change of 0.656%, 0.889% and 0.488% for FITC-LCA, FITC-LCA-LTF and FITC-LCA-STF complexes, respectively. Fluorescence intensity quenching with iodide and thermal quenching experiments indicate that the dynamics of LCA increase as the result of the flexibility of the carbohydrate residues (case of STF-LCA complex), and the presence of the alpha-1,6-fucose inhibits the effect of the other carbohydrate residues as the result of the tight bond that exists between the fucose and the lectin (case of LTF-LCA complex).

Fluorescein-5-isothiocyanate↗
PubMed2002

Novel caged fluorescein diphosphates as photoactivatable substrates for protein tyrosine phosphatases.

We have characterized some novel caged fluorescein diphosphates as photoactivatable, cell-permeable substrates for protein tyrosine phosphatases and explored their usefulness in identifying inhibitors of tyrosine phosphatases. 1-(2-Nitrophenyl)ethyl protected fluorescein diphosphate (NPE-FDP) undergoes rapid photolysis to release FDP upon irradiation with a 450-W UV immersion lamp and its by-product does not inactivate protein tyrosine phosphatase 1B (PTP1B) or alters the viability of cells. The generated FDP from photolysis of NPE-FDP was shown to have exactly the same properties as FDP, which can be used as a PTP substrate in pure enzyme assays. We have also demonstrated that the PTP activity can be measured using NPE-FDP in small droplets. Its advantage as an inert substrate before photolysis allows the possibility of applying nanospray technology in screening and optimizing PTP inhibitors through a large chemical library. Like other caged bioeffectors such as nucleotide and inositol trisphosphate, NPE-FDP is cell-permeable. The NPE-FDP can be photolyzed to generate FDP inside cells, and then can be hydrolyzed by phosphatases to produce fluorescein monophosphate and subsequently to fluorescein. Although Jurkat cells contain high concentrations of CD45, it has not been possible to use FDP as a substrate to measure CD45 activity in the intact cell. This is due to the hydrolysis of FDP by several other cellular phosphatases. However, NPE-FDP can be useful as a cell-permeable substrate for overexpressed phosphatases such as alkaline phosphatase.

Animals↗
PubMed1994

Investigation of specific binding of antifluorescyl antibody and Fab to fluorescein lipids in Langmuir-Blodgett deposited films using quartz crystal microbalance methodology.

Antifluorescyl IgG antibody and Fab binding to two fluorescein-conjugated lipids was measured using the quartz crystal microbalance methodology. By use of the Langmuir-Blodgett technique, the fluorescein lipids, which were diluted to 5% in a L-alpha-dipalmitoyl phosphatidylethanolamine (DPPE) matrix, were deposited directly onto one gold electrode of the quartz crystal. Binding to films containing the fluorescein hapten was significantly enhanced compared to films of the pure DPPE matrix lipid, indicating that binding occurred primarily through a specific interaction. Association constants were 40-300 times less than for binding to haptens free in solution. Binding of IgG to the lipid in which the hydrocarbon chains and the fluorescein hapten were linked via a hydrophilic spacer was approximately 7 times as great as to the lipid containing no spacer. IgG binding to the lipid containing the spacer was increased 1.5-4.4 times compared to Fab binding for the same lipid. Equilibrium binding curves and kinetic measurements are analyzed quantitatively and compared.

Animals↗
PubMed2001

Rational design of fluorescein-based fluorescence probes. Mechanism-based design of a maximum fluorescence probe for singlet oxygen.

Fluorescein is one of the best available fluorophores for biological applications, but the factors that control its fluorescence properties are not fully established. Thus, we initiated a study aimed at providing a strategy for rational design of functional fluorescence probes bearing fluorescein structure. We have synthesized various kinds of fluorescein derivatives and examined the relationship between their fluorescence properties and the highest occupied molecular orbital (HOMO) levels of their benzoic acid moieties obtained by semiempirical PM3 calculations. It was concluded that the fluorescence properties of fluorescein derivatives are controlled by a photoinduced electron transfer (PET) process from the benzoic acid moiety to the xanthene ring and that the threshold of fluorescence OFF/ON switching lies around -8.9 eV for the HOMO level of the benzoic acid moiety. This information provides the basis for a practical strategy for rational design of functional fluorescence probes to detect certain biomolecules. We used this approach to design and synthesize 9-[2-(3-carboxy-9,10-dimethyl)anthryl]-6-hydroxy-3H-xanthen-3-one (DMAX) as a singlet oxygen probe and confirmed that it is the most sensitive probe currently known for (1)O(2). This novel fluorescence probe has a 9,10-dimethylanthracene moiety as an extremely fast chemical trap of (1)O(2). As was expected from PM3 calculations, DMAX scarcely fluoresces, while DMAX endoperoxide (DMAX-EP) is strongly fluorescent. Further, DMAX reacts with (1)O(2) more rapidly, and its sensitivity is 53-fold higher than that of 9-[2-(3-carboxy-9,10-diphenyl)anthryl]-6-hydroxy-3H-xanthen-3-ones (DPAXs), which are a series of fluorescence probes for singlet oxygen that we recently developed. DMAX should be useful as a fluorescence probe for detecting (1)O(2) in a variety of biological systems.

Fluorescein↗
PubMed1990

Solute absorption from the airways of the isolated rat lung. II. Effect of surfactants on absorption of fluorescein.

To determine the effects on the pulmonary barrier of several surface active agents, a series of metered dose inhalers (MDIs) was prepared and used to dose aerosolized surfactant to the airways of isolated perfused rat lungs. The MDIs contained a range of concentrations, from 0.1 to 5.0% (w/w), of either oleic acid, oleyl alcohol, or Span 85, which released approximately 45 micrograms (0.1%, w/w) to approximately 1660 micrograms (5.0%, w/w) of surfactant per actuation. The permeability of the pulmonary barrier was assessed by the rate of transfer of disodium fluorescein dosed as 100 microliters of aqueous solution (1 mg/ml) after administering the surfactants. Some 12.1 +/- 4.7% of the recovered surfactant, per dose, was assessed to reach the pulmonary regions of the lung. All surfactants tested caused an increase in fluorescein transfer rates. A single actuation from the MDI containing 5% (w/w) oleic acid produced gross edema in all lungs tested within 40 min and the first-order half-lives of absorption were reduced almost threefold, from 12.9 +/- 2.5 min for controls to 4.5 +/- 0.8 min. Differences in absorption were noted between the acid and the alcohol, which is consistent with the hypothesis that both the hydrocarbon chain and the polar head group have roles in the altered permeability to fluorescein. The absorption of fluorescein when dosed from the MDI containing 5% (w/w) Span 85 was increased but all surfactants dosed from the lowest concentration MDI of 0.1% (w/w) did not alter absorption rates of the dye relative to those of controls. Results are discussed in light of current interest in absorption enhancement and the presence of surfactants in currently marked MDIs.

Absorption↗