Fluorescein Concentration Research Articles

Effects of loading concentration, blood and synovial fluid on antibiotic release and anti-biofilm activity of bone cement beads

Antibiotic loaded cement beads are commonly used for the treatment of biofilm related orthopaedic periprosthetic infections; however the effects of antibiotic loading and exposure of beads to body fluids on release kinetics are unclear. The purpose of this study was to determine the effects of (i) antibiotic loading density (ii) loading amount (iii) material type and (iv) exposure to body fluids (blood or synovial fluid) on release kinetics and efficacy of antibiotics against planktonic and lawn biofilm bacteria. Short-term release into an agar gel was evaluated using a fluorescent tracer (fluorescein) incorporated in the carrier materials calcium sulfate (CaSO4) and poly methyl methacrylate (PMMA). Different fluorescein concentrations in CaSO4 beads were evaluated. Mechanical properties of fluorescein-incorporated beads were analyzed. Efficacy of the antibiotics vancomycin (VAN) or tobramycin (TOB) alone and in combination was evaluated against lawn biofilms of bioluminescent strains of Staphylococcus aureus and Pseudomonas aeruginosa. Zones of inhibition of cultures (ZOI) were measured visually and using an in-vivo imaging system (IVIS). The influence of body fluids on release was assessed using CaSO4 beads that contained fluorescein or antibiotics and were pre-coated with human blood or synovial fluid. The spread from the beads followed a square root of time relationship in all cases. The loading concentration had no influence on short-term fluorescein release and pre-coating of beads with body fluids did not affect short-term release or antibacterial activity. Compared to PMMA, CaSO4 had a more rapid short term rate of elution and activity against planktonic and lawn biofilms. This study highlights the importance of considering antibiotic loading and packing density when investigating the clinical application of bone cements for infection management.

Determination of Microbial Activities and Biomass in Biofilm Associated with Treatment Wetlands Compartments to Investigate Active Pollutant Processing Site

Although Floating treatment wetlands (FTWs) provide immense advantages over other natural treatment facilities, there is no information about biofilm functioning and microbial-based processes in FTW. Therefore, this study was aimed to evaluate the magnitude of microbial-based processes in the root, bottom and water column zones of the FTW by employing of macrophytes. For this experiment, primary domestic wastewater effluent was used in two pairs of FTWs (I. psuedacorus and P. stratiotes) and a pair of control. Total microbial activity was estimated using FDA hydrolytic activity and specific microbial activities were examined as denitrification and nitrification activities, whilst viable microbial number and distribution in the FTW compartments were determined using ATP assay. The average nitrification rates in the FTWs were 0.55, 0.81 and 2.75 μg/ml of water, gravel and root surface per hour respectively; and denitrification rates were 0.022, 0.053 and 0.132 μg/ml of water, gravel and roots surface respectively. The mean fluorescein concentration for the FTWs were 9.2, 1.1 and 0.06 μg/ml of root, gravel and freewater respectively, indicating that the highest total microbial activity in the FTW occurs in the biofilm associated with the root system. Mean viable microbial community 3.85 × 108, 3.7 × 107 and 1.3 × 107 cells/ml of root surface, water and gravel surface. Therefore, all the result suggested that active pollutant removal in all FTW stakes place in the root zone.

Electroconvulsive stimulation transiently enhances the permeability of the rat blood-brain barrier and induces astrocytic changes

The blood-brain barrier (BBB) plays important roles in both the physiological and pharmacological state of the brain. Transiently enhancing the permeability of the BBB may allow use of more types of medications for neuropsychiatric diseases. Several studies have demonstrated that seizures cause a transient decrease in BBB integrity. We studied the timing of BBB changes following seizures and the role of astrocytes in this process. Rats received 10 applications of electroconvulsive stimulation (ECS). They were then infused with sodium fluorescein, a fluorescent substance that rarely passes the BBB, via the inferior vena cava. After 120min of circulation, the amount of sodium fluorescein in the brain was measured by two methods in vivo fluorescence imaging (total radiant efficiency) and the brain concentration of sodium fluorescein. To assess any changes to the BBB, we measured S100Β in serum, which is a standard marker of BBB breakdown that is expressed by astrocytes. We also examined ultrastructural changes following ECS. Total radiant efficiency and the brain concentration of sodium fluorescein were significantly increased in treated rats compared to controls when sodium fluorescein was injected immediately after ECS but not when the injection was performed more than 15 min after ECS. Astrocytic endfeet showed swelling around brain capillaries following ECS. In conclusion, ECS transiently enhances the permeability of the BBB, which may be accompanied by changes in astrocytic endfeet.

Pancreatic Functional Evaluation in Metabolic Syndrome

Introduction: Metabolic Syndrome (MS) has insulin resistance as main metabolic alteration. Insulin secretion involves directly the islets of Langerhans, which are the endocrine component of the pancreas. Through interaction of the exocrine-endocrine axis, it affects the pancreatic acinus, which is the exocrine component of the gland. The Pancreolauryl Test (PLs) measures indirectly the exocrine function through the action of an enzyme, the specific pancreatic cholesterol esterase, inside the intestinal lumen. The Pancreatogram evaluates globally the pancreatic function. Objective: To evaluate in MS patients, in distinction to the control patients, the pancreatic exocrine-endocrine function. Methods: Patients of both genders, range (33-72) years old: control (n=30) and MS (n=41), diagnosed regarding the ATPIII criteria. The endocrine-exocrine axis was evaluated through: Pancreatogram: amplified oral glucose tolerance test, we determine the 0,30,60 and 120minutes post stimulation (mps) values in serum, of glucose(Glu) and Insuline(Ins). Also, amylase(Ami), pancreatic amylase(AMI-P) and lipase(LIP) activity at time 0. PLs: It's determined at 0,60,120,150,180,210,240 mps. We measure serum concentration of fluorescein, which is released from fluorescein dilaurate, substrate of the pancreatic enzyme. Statistic analysis: Student Test. InfoStat. p < 0,05 Results: results are shown at the table as Mean± Standard Deviation Results: Table 1 Conclusion: hyperglucemia with hyperinsulimenia at all points of the curve manifests insulin resistance in the fasting state (hepatic) and peripheral tissue resistance is put in evidence at points 30 and 60 of the Pancreatogram. The insulin values in MS patients double the control values. AMY and LIP activity in MS patients is within reference values, but AMI activity is significantly higher than the control at expense of the AMI-P isoenzyme, which suggests insulin's action in the pancreon. The classic hyperinsulinemia found in MS, would stimulate amylase secretion and would inhibit partially lipase secretion. PLs of MS patients were significantly lower than those of the control, in fact, 46% (19) showed results below the cut value (4,5 mg/l), evidence of a diminished exocrine function. These results show the need to perform a pancreatogram and the importance of evaluating insulin in MS patients. We proved the gland's alteration at its endocrine component, in the context of a syndrome based on an endocrine metabolic alteration.Figure 1

Cobalt thiolate complexes catalyst in noble-metal-free system for photocatalytic hydrogen production

Thiolate complexes Co(bpy)(pyS)2 (M) were synthesized, the effect of reaction conditions (such as pH values, solvents, electron donor, photosensitizers, catalyst, and concentrations) on catalytic performance of catalyst M was studied and the optimum reaction conditions were selected. The results of catalytic performance imply that complexes M showed good catalytic activity when concentration of catalyst M was 2.5 μM, concentration of fluorescein was 2.0 mM, pH value was 11.6, electron donor was triethylamine (5%), and the solvent was EtOH/H2O (1: 1 V/V). The catalysis system presented the best performance and hydrogen production reached 369.2 μmol h–1 after reacting for 15 h; the life of catalyst M was 41 h investigated under the optimum conditions.

Potency and Sterility of 10% Sodium Fluorescein Injection, USP Stored in Sterile Polypropylene Syringes for Use During Cystoscopy.

Background: A shortage of indigotindisulfonate sodium has led to a search for an alternative visualizing agent. Objective: The primary objective of this study was to evaluate the potency and sterility of 10% sodium fluorescein, USP solutions stored in sterile polypropylene syringes and refrigerated. Methods: Four samples of 10% fluorescein injection, USP were aseptically drawn up in 3 mL polypropylene syringes and stored in a refrigerator at an average temperature of 3.9°C for 7 days. After 7 days, the samples were cultured for microbial growth. Four other samples were assayed by UV/VIS spectroscopy. Concentration measurements were made at day 0 and at day 7. The pH was also measured at day 0 and day 7. Results: There was no statistical difference between the mean sodium fluorescein concentration at day 0 and at day 7 (α = 0.05, p = .622). There was no statistical difference in the pH of the samples at day 0 and at day 7 (α = 0.05, p = .0689). There was no evidence of microbial growth in any of the samples for the duration of the study period. Conclusions: The findings of this study demonstrate that a sterile solution of 10% sodium fluorescein, USP retained its potency and showed no signs of microbial growth for a period of 7 days when refrigerated and stored in sterile polypropylene syringes.

Water transport in leaf vein systems and the flow velocity measurement with a new method

As an exploration to the nature, research about plants⿿ physiological properties have never been suspended. Water transport in leaf vein systems is an essential part of plant growth and development. In this paper, a simple but efficient method combined the fluorescence labeling technology frequently used in bioresearch and the image-processing technology in the computer realm was developed to measure the flow velocity, which was used as a quantitative description to reveal the regulation of water transport in leaf vein systems. Three ordinary species of plants were selected for the experiments and the influence of the experimental conditions, such as the concentration of fluorescein and illumination intensity of LEDs, was investigated. Differences among the flow velocities of different leaf veins of the same leaf as well as the flow velocities of different species were shown in bar charts. The mean measured flow velocities of the midrib and secondary vein of Ficus virens Ait. var. sublanceolata (Miq.) Corner were 4.549m/h and 3.174m/h. As for Plumeria rubra L. cv. Acutifolia and Hamelia patens, that were 0.339m/h and 0.463m/h, 2.609m/h and 2.586m/h, respectively. With the algorithm developed in this paper, the variation of the flow velocity in leaf veins was investigated by setting a constant time interval. Then a verification of the flow velocity measured by the algorithm was performed. Finally, according to the natural conditions of a plant leaf, a simulation about the water transport in leaf vein systems was carried out, which is especially different from the previous research.

Aqueous Flow Measured by Fluorophotometry in the Mouse.

PurposeA fluorophotometer designed to measure aqueous flow in murine eyes was tested with artificial fluorescein chambers and in live mice with different anesthesia regimens, aqueous flow suppressants, and an anterior chamber cannulation method.MethodsTwo hours following topical fluorescein application, one group of CD-1 mice was anesthetized with ketamine/xylazine, 2,2,2-tribromoethanol, or ketamine alone. Cornea and anterior chamber fluorescein concentrations were measured periodically for 60 to 90 minutes by fluorophotometric scans to calculate aqueous flow. Later, a subgroup of mice underwent aqueous flow measurement by anterior chamber cannulation. A third group was treated with timolol, dorzolamide, and vehicle in a crossover manner 1 hour prior to fluorophotometric scans.ResultsAqueous flow with ketamine/xylazine anesthesia (0.09 ± 0.05 μL/min, mean ± SD, n = 24) was slower than with tribromoethanol or ketamine alone (P < 0.001). Timolol reduced aqueous flow from 0.20 ± 0.07 μL/min to 0.07 ± 0.03 μL/min (P = 0.001) under tribromoethanol anesthesia and from 0.14 ± 0.03 μL/min to 0.10 ± 0.02 μL/min (P = 0.004) under ketamine anesthesia but not under ketamine/xylazine anesthesia. Dorzolamide reduced aqueous flow from 0.09 ± 0.03 to 0.06 ± 0.03 μL/min (P = 0.04) under ketamine/xylazine anesthesia. Aqueous flow by anterior chamber cannulation (0.20 ± 0.13 μL/min) was greater (P = 0.05) than by fluorophotometry (0.09 ± 0.07 μL/min).ConclusionsA new noninvasive fluorophotometric method detected effects of general anesthesia and known aqueous suppressants on aqueous flow in mice. Aqueous flow measured by fluorophotometry was slower than by cannulation, and was technically easier with less variability. The mouse fluorophotometer is useful for repeated measurements of aqueous flow in the murine eye making crossover and longitudinal studies possible.

Graphene-based biosensors

Results of developing and testing graphene-based sensors capable of detecting protein molecules are presented. The biosensor operation was checked using an immunochemical system comprising fluorescein dye and monoclonal antifluorescein antibodies. The sensor detects fluorescein concentration on a level of 1–10 ng/mL and bovine serum albumin–fluorescein conjugate on a level of 1–5 ng/mL. The proposed device has good prospects for use for early diagnostics of various diseases.

Corneal permeability changes in dry eye disease: an observational study.

BackgroundDiagnostic tests for dry eye disease (DED), including ocular surface disease index (OSDI), tear breakup time (TBUT), corneal fluorescein staining, and lissamine staining, have great deal of variability. We investigated whether fluorophotometry correlated with previously established DED diagnostic tests and whether it could serve as a novel objective metric to evaluate DED.MethodsDry eye patients who have had established signs or symptoms for at least 6 months were included in this observational study. Normal subjects with no symptoms of dry eyes served as controls. Each eye had a baseline fluorescein scan prior to any fluorescein dye. Fluorescein dye was then placed into both eyes, rinsed with saline solution, and scanned at 5, 10, 15, and 30 min. Patients were administered the following diagnostic tests to correlate with fluorophotometry: OSDI, TBUT, fluorescein, and lissamine. Standard protocols were used. P < 0.05 was considered significant.ResultsFifty eyes from 25 patients (DED = 22 eyes, 11 patients; Normal = 28 eyes, 14 patients) were included. Baseline scans of the dry eye and control groups did not show any statistical difference (p = 0.84). Fluorescein concentration of DED and normal patients showed statistical significance at all time intervals (p < 10−5, 0.001, 0.002, 0.049 for 5, 10, 15, & 30 min respectively). Fluorophotometry values converged towards baseline as time elapsed, but both groups were still statistically different at 30 min (p < 0.01). We used four fluorophotometry scoring methods and correlated them with OSDI, TBUT, fluorescein, and lissamine along with adjusted and aggregate scores. The four scoring schemes did not show any significant correlations with the other tests, except for correlations seen with lissamine and 10 (p = 0.045, 0.034) and 15 min (p = 0.013, 0.012), and with aggregate scores and 15 min (p = 0.042, 0.017).ConclusionsFluorophotometry generally did not correlate with any other DED tests, even though it showed capability of differentiating between DED and normal eyes up to 30 min after fluorescein dye instillation. There may be an aspect of DED that is missed in the current regimen of DED tests and only captured with fluorophotometry. Adding fluorophotometry may be useful in screening, diagnosing, and monitoring patients with DED.

Multicolor Fluorescence Detection for Droplet Microfluidics Using Optical Fibers

Fluorescence assays are the most common readouts used in droplet microfluidics due to their bright signals and fast time response. Applications such as multiplex assays, enzyme evolution, and molecular biology enhanced cell sorting require the detection of two or more colors of fluorescence. Standard multicolor detection systems that couple free space lasers to epifluorescence microscopes are bulky, expensive, and difficult to maintain. In this paper, we describe a scheme to perform multicolor detection by exciting discrete regions of a microfluidic channel with lasers coupled to optical fibers. Emitted light is collected by an optical fiber coupled to a single photodetector. Because the excitation occurs at different spatial locations, the identity of emitted light can be encoded as a temporal shift, eliminating the need for more complicated light filtering schemes. The system has been used to detect droplet populations containing four unique combinations of dyes and to detect sub-nanomolar concentrations of fluorescein.

Multicolor Fluorescence Detection for Droplet Microfluidics Using Optical Fibers.

Fluorescence assays are the most common readouts used in droplet microfluidics due to their bright signals and fast time response. Applications such as multiplex assays, enzyme evolution, and molecular biology enhanced cell sorting require the detection of two or more colors of fluorescence. Standard multicolor detection systems that couple free space lasers to epifluorescence microscopes are bulky, expensive, and difficult to maintain. In this paper, we describe a scheme to perform multicolor detection by exciting discrete regions of a microfluidic channel with lasers coupled to optical fibers. Emitted light is collected by an optical fiber coupled to a single photodetector. Because the excitation occurs at different spatial locations, the identity of emitted light can be encoded as a temporal shift, eliminating the need for more complicated light filtering schemes. The system has been used to detect droplet populations containing four unique combinations of dyes and to detect sub-nanomolar concentrations of fluorescein.

A Supercritical Fluid-Based Process for the Production of Fluorescein-Loaded Liposomes

Fluorescein is a synthetic dye used as a marker to monitor the absorption of liposomes into tissues, but its efficient entrapment is still challenging. In this work, we apply a supercritical fluid process that allows the production of liposomes with a high drug encapsulation efficiency. The effects of operating parameters such as the diameter of the injector, the concentration of phospholipids, and the concentration of fluorescein were studied. Liposomes with mean diameters down to ∼300 nm were obtained with fluorescein encapsulation efficiencies of ≤96%. In detail, the increase in the concentration of phospholipids produced a relative increase in liposome mean diameter and particle size distribution width. With an increase in fluorescein theoretical loading, instead, a reduction in liposome mean diameters and standard deviation was obtained. Smaller liposomes were produced using smaller injector diameters; however, the reduction of the injector diameter from 80 to 40 μm caused a reduction in the fluoresc...

Fluorescence lifetime imaging microscopy reveals quenching of fluorescein within corneal epithelium

Topical application of fluorescein results in background fluorescence of normal corneal epithelial cells. The fluorescence appears relatively weak and is often ignored clinically. The concentrations of fluorescein applied clinically exceed the threshold for self quenching. The possibility that exuberant topical concentrations of fluorescein result in quenching of fluorescence in tears and normal corneal epithelium is explored. Fluorescence lifetime measurements are sensitive to quenching and are less vulnerable to inner filter effect than steady state measurements. The types of fluorescence lifetime quenching often report informative molecular interactions. Therefore, fluorescence lifetime confocal imaging was performed in solutions, tears and corneal epithelium removed by membrane cytology following applied fluorescein. Amplitude averaged fluorescence lifetimes (τamp) were measured with time resolved single photon counting using a pulsed diode laser for excitation of fluorescein. Lifetime decays were fit to multi-exponential models with least squares analysis. Stern-Volmer plots for both intensity (I) and (τamp) were determined. Stern-Volmer plots demonstrated both dynamic and static quenching components (R2 = 0.98 exponential fit, I0/I). Plots of τamp versus concentration of fluorescein revealed a linear relationship. Immediately after fluorescein application, quenching was evident in tears (τamp < 1 ns) versus tears sampled after 5 min (τamp = 3.7 ns). Corneal epithelium showed quenching (τamp ≤ 2 ns) from 1 to 16 min post fluorescein instillation. Clinical concentrations of fluorescein show self-quenching but rapidly dilute as tears turnover. Intracellular quenching occurs in normal corneal epithelium. Lifetime decay curves suggest complex mechanisms are involved. Quenching is a plausible explanation for the low fluorescence background observed clinically.

Improvement and Interlaboratory Validation of the Lipophilic Oxygen Radical Absorbance Capacity: Determination of Antioxidant Capacities of Lipophilic Antioxidant Solutions and Food Extracts.

A lipophilic oxygen radical absorbance capacity (L-ORAC) assay is an evaluation of the antioxidant capacity of solutions of lipophilic compounds. The concentrations of fluorescein, radical generator, and Trolox standard solutions were optimized to improve the precision of the assay. An interlaboratory study using two antioxidant solutions and three food extracts as test samples conducted in accordance with harmonized protocol demonstrated satisfactory L-ORAC measurements; the intermediate precision relative standard deviations (RSD(int)) ranged from 7.0 to 16.7%, the reproducibility relative standard deviations (RSD(R)) ranged from 14.8 to 19.4%, and the HorRat values ranged from 1.35 to 1.78.

Experimental recovery of intrinsic fluorescence and fluorophore concentration in the presence of hemoglobin: spectral effect of scattering and absorption on fluorescence.

The ability to recover the intrinsic fluorescence of biological fluorophores is crucial to accurately identify the fluorophores and quantify their concentrations in the media. Although some studies have successfully retrieved the fluorescence spectral shape of known fluorophores, the techniques usually came with heavy computation costs and did not apply for strongly absorptive media, and the intrinsic fluorescence intensity and fluorophore concentration were not recovered. In this communication, an experimental approach was presented to recover intrinsic fluorescence and concentration of fluorescein in the presence of hemoglobin (Hb). The results indicated that the method was efficient in recovering the intrinsic fluorescence peak and fluorophore concentration with an error of 3% and 10%, respectively. The results also suggested that chromophores with irregular absorption spectra (e.g., Hb) have more profound effects on fluorescence spectral shape than chromophores with monotonic absorption and scattering spectra (e.g., black India ink and polystyrene microspheres).

Novel Fluorometric Method for the Determination of Production Rate and Steady-State Concentration of Photochemically Generated Superoxide Radical in Seawater Using 3',6'-(Diphenylphosphinyl)fluorescein.

Superoxide radical (O2(•-)) is an important reactive oxygen species in seawater. Measurements of its production rates and steady-state concentrations generated by photochemical processes have been a Herculean task over the years. In this study, a probe - 3'6'-(diphenylphosphinyl)fluorescein (PF-1) - was used to trap photochemically generated O2(•-) in seawater, thereby yielding fluorescein. The fluorescein produced was measured by an isocratic fluorescence HPLC at excitation/emission wavelengths of 490/513 nm, respectively. The reaction rate constant of PF-1 with O2(•-) (kPF-1) was pH-dependent: (3.2-23.5) × 10(7) M(-1) s(-1) at pHTOT 7.65-8.50. By applying appropriate equations, both the production rate and the steady-state concentration of O2(•-) generated by photochemical reactions in the seawater were quantified. Under the optimized experimental conditions, fluorescein standards (3-50 nM) exhibited linearity in the seawater by HPLC. The photoformation of fluorescein, due to the reaction of PF-1 with the O2(•-) photochemically produced in the seawater, was linear within the 20 min irradiation. The detection limit of the fluorescein photoformation rate was 0.03 pM s(-1), defined as 3σ of the lowest standard fluorescein concentration per 20 min irradiation. Using this value, the yield of fluorescein, and the fraction of O2(•-) that reacted with PF-1 in the seawater, the detection limit of the O2(•-) photoformation rate was 1.78 pM s(-1). Superoxide measurements using the proposed method were relatively unaffected by the potential interfering species in seawater. Application of the proposed method to ten (10) seawater samples from the Seto Inland Sea, Japan, resulted in measured O2(•-) photoformation rates of 3.1-8.5 nM s(-1), with steady-state concentrations ranging (0.06-0.3) × 10(-10) M. The method is simple, requires no technical sample preparation, and can be used to analyze a large number of samples.

Evaluation of fluorescent dye degradation indirectly induced by x-ray ionizing radiation.

This work evaluated the fluorescent dye degradation indirectly induced by ionizing radiation with high energy photons (50keV). Aqueous gels of agarose with low concentrations of Rhodamine 6G and Fluorescein were submitted to doses of x-ray radiation up to 200Gy. The dye degradation was analyzed by fluorescence spectroscopy, using an excitation light-emitting diode with a peak wavelength of 462nm. A rate equation model of fluorophores and radicals' species populations was developed to describe the degradation time behavior of the fluorescent solutions. The model suggests fluorescent dyes should be used in dosimetry.

The Effects of Increasing Ocular Surface Stimulation on Blinking and Tear Secretion.

To investigate the effect of varying levels of ocular surface stimulation on the timing and amplitude of the blink and tear secretion. Following instillation of fluorescein dye, increasing levels of air flow were directed toward the central corneas of 10 healthy subjects. Interblink interval (IBI), tear meniscus height (TMH), and fluorescence intensity were measured simultaneously. Because blinking can obscure changes in TMH, we developed novel measures of tear secretion by calculating tear meniscus fluorescein concentration (TMFC) from intensity using a mathematical model. The change of TMH and TMFC over trials and the slope of the TMFC within each IBI (IBI-TTR) were further calculated. The mean IBI was decreased by 8.08 ± 8.54 seconds from baseline to maximum air stimulation. The TMH increase was highly variable (0.41 ± 0.39 mm) among subjects, compared to the fluorescence tear turnover metrics: decrease in TMFC of 2.84 ± 0.98 natural logarithm or ln(%) and IBI-TTR of 0.065 ± 0.032 ln(%)/sec. Ocular surface stimulation was highly correlated with the TMFC and IBI-TTR, but less so with TMH (Pearson's r = 0.71, 0.69, and 0.40, P < 0.01, respectively). Blinking and tearing were significantly correlated with each other (Pearson's r = 0.56, P < 0.01), but tearing lagged behind by an average of 6.54 ± 4.07 seconds. Blinking and tearing share a common origin with sensory stimulation at the ocular surface. Both showed a dose-response increase with surface stimulation and were correlated with each other. These methods can potentially be used to understand alterations in ocular surface sensory function and associated protective responses in dry eye and other disorders of the ocular surface.

Effects of Pringle maneuver and partial hepatectomy on the pharmacokinetics and blood–brain barrier permeability of sodium fluorescein in rats

Liver diseases are known to affect the function of remote organs. The aim of the present study was to investigate the effects of Pringle maneuver, which results in hepatic ischemia–reperfusion (IR) injury, and partial hepatectomy (Hx) on the pharmacokinetics and brain distribution of sodium fluorescein (FL), which is a widely used marker of blood–brain barrier (BBB) permeability. Rats were subjected to Pringle maneuver (total hepatic ischemia) for 20min with (HxIR) or without (IR) 70% hepatectomy. Sham-operated animals underwent laparotomy only. After 15min or 8h of reperfusion, a single 25-mg/kg dose of FL was injected intravenously and serial (0–30min) blood and bile and terminal brain samples were collected. Total and free (ultrafiltration) plasma, total brain homogenate, and bile concentrations of FL and/or its glucuronidated metabolite (FL-Glu) were determined by HPLC. Both IR and HxIR caused significant reductions in the biliary excretions of FL and FL-Glu, resulting in significant increases in the plasma AUC of the marker. Additionally, the free fraction of FL in plasma was significantly increased by HxIR. Although the brain concentrations of FL were increased by almost twofold in both IR and HxIR animals, the brain concentrations corrected by the free FL AUC (and not the total AUC) were similar in both groups at either time points. It is concluded that Pringle maneuver and/or partial hepatectomy substantially alters the hepatobiliary disposition, plasma AUC, plasma free fraction, and brain accumulation of FL without altering the BBB permeability to the marker.