Concentration Of Sodium Fluorescein Research Articles

Increased Permeability of the Blood-Brain Barrier in a Diabetic Mouse Model (Leprdb/db Mice).

Type 2 Diabetes Mellitus (T2DM) is linked to multiple complications, including cognitive impairment, and the prevalence of memory-related neurodegenerative diseases is higher in T2DM patients. One possible theory is the alteration of the microvascular and macrovascular environment of the blood-brain barrier (BBB). In this study, we employed different approaches, including RT-PCR, functional pharmacokinetic studies using sodium fluorescein (NaFL), and confocal microscopy, to characterize the functional and molecular integrity of the BBB in a T2DM animal model, leptin receptor-deficient mutant mice (Leprdb/db mice). As a result, VCAM-1, ICAM-1, MMP-9, and S100b (BBB-related markers) dysregulation was observed in the Leprdb/db animal model compared to littermate wild-type mice. The brain concentration of sodium fluorescein (NaFL) increased significantly in Leprdb/db untreated mice compared to insulin-treated mice. Therefore, the permeability of NaFL was higher in Leprdb/db control mice than in all remaining groups. Identifying the factors that increase the BBB in Leprdb/db mice will provide a better understanding of the BBB microvasculature and present previously undescribed findings of T2DM-related brain illnesses, filling knowledge gaps in this emerging field of research.

Zero-Order Controlled Release of Water-Soluble Drugs Using a Marker Pen Platform.

Zero-order drug release that releases drugs at a constant rate is beneficial to prolong the therapeutic effect and avoid the side effects of drugs. However, due to the weak interaction between the drug and the carrier, it is particularly challenging to achieve zero-order release of water-soluble drugs. Inspired by the marker pen, which stores the water-based ink in the sponge core and releases a constant amount of ink from the tip for writing, we explore the marker pen as a drug delivery platform to achieve zero-order release of water-soluble drugs. Through the capillary interaction between the material and water, the pen core can absorb the aqueous drug solution to encapsulate and store the water-soluble drug model sodium fluorescein (SF) and can release the encapsulated SF by moving the pen tip across the surface. The results show that the marker pen can release a constant amount of SF at the nanogram level per unit length of the line drawn with the pen, and the cumulative SF release amount has a linear relationship with the length of the line. In addition, the amount of released SF is linear with respect to the SF concentration in the aqueous solution. Moreover, the SF-filled marker pen has excellent long-term stability as evidenced by that the amount of SF released from the pen remains constant within two weeks after filling.

Infusion efficiency of sodium fluorescein into various starches.

The objective of this study was to develop new drug delivery systems (DDS) and nutrient delivery systems (NDS), using starch as a carrier material for infusion technology. Corn, waxy rice, non-waxy rice, and potato starches were used as carrier materials. Sodium fluorescein was used as an infusion material for easy detection. Each starch suspension with sodium fluorescein was reacted in a water bath at 40, 50, and 60°C for 30min. After each reaction, the concentration of sodium fluorescein in the supernatant was measured using a fluorescence detector. Precipitated starch was observed using fluorescence microscopy. About 70% of sodium fluorescein infused in waxy rice and corn starches at 60°C. Additionally, the granules of these two starches were luminous by green light when exposed to a fluorescence detector, suggesting that corn and waxy rice starches can be used as carrier materials in infusion technology for DDS and NDS.

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.

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.

Effect of sodium fluorescein on release characteristics of a macromolecule from calcium alginate gel beads

This study describes a detailed investigation of swelling and release behavior of a macromolecule from calcium alginate gel (CAG) beads in the presence of a small molecule, sodium fluorescein (SF). Blue dextran (BD) was used as a model macromolecule. The bead diameter was slightly different after soaking in various concentrations of SF although the SF uptake into calcium gel beads is markedly different. The swelling kinetics of CAG beads showed the rapid hydration and reached a maximum within 6 h. It is thought that the effect of SF, which is predominant in the swelling of CAG beads without BD, was hindered by the entanglement of BD. It appeared that the SF concentration has an effect on the BD release; the higher the SF concentration, the higher amount of BD released from the CAG beads. The release from this system basically follows Fick's law (Higuchi's expression). The increase in SF concentration decreased the Higuchi release coefficient. It was observed that the effect of small molecule is quite obvious, since the difference in Higuchi release coefficients of the CAG beads soaked in 1000-μg SF is less than non-soaked beads, about 25%.

Ultrasound-enhanced drug delivery through sclera.

Achieving an increase in drug delivery through the sclera is important in the treatment of the back of the eye diseases including macular degeneration, diabetic retinopathy, etc. Our objective is to utilize therapeutic ultrasound in enhancing drug delivery through the sclera. Porcine sclera was placed in a standard diffusion cell at a normal physiological temperature of 34 °C. Solution of sodium fluorescein, a hydrophilic drug-mimicking compound, was added to donor compartment, and receiver compartment was filled with saline. The sclera was exposed to ultrasound for 5 min (intensities 1.2–1.8 W/cm2 and frequencies 0.5 to 5 MHz). After 60 min, solution samples were taken from the receiver compartment to determine the concentration of sodium fluorescein. The sclera permeability to the drug mimicking agent in vitro increased 3.5 times at 0.5 MHz (p-value of less than 0.05), 1.7 times at 1 MHz, 3.5 times at 3.5 MHz (p-value of less than 0.05), and 1.5 times at 5 MHz. The average temperature of the sclera during ultrasound exposure was 42 °C. No gross changes were observed in the sclera due to ultrasound application. Future work will focus on determination of optimal ultrasound parameters for the drug delivery through the sclera.

フルオレセインの土壌吸着挙動に関する研究―Ｆｒｅｕｎｄｌｉｃｈ吸着式による解析―

In order to examine soil adsorption behavior of fluorescein, adsorption-equilibrium experiments were carried out. The soil samples used in this study are Kuroboku soil, Yellow brown forest soil, Kanuma soil and Peat. The parameters on the experiments were the initial concentration of sodium fluorescein (0.1, 1, 10 mg/l) and the mass ratio of soil to liquid (0.001, 0.01, 0.1). When the mass ratio were 0.001 and 0.1, the quantity of fluorescein adsorbed on soils was Kuroboku ≒ Yellow brown forest > Peat >> Kanuma. However, the adsorbed amount on Kanuma was remarkably small and there was not so different among the adsorbed amounts on the other soils. The particle size of soils did not affect the absorbed amount. The BET specific surface area was ranged as Kanuma > Yellow brown forest > Kuroboku > Peat. The absorbed amount on Kanuma having the largest BET specific surface area was the least. Therefore the number of the pore effectively utilized for the adsorption of fluorescein seems to be dependent on the type of soil. The clear correlation could not be found between absorbed amount of fluorescein and each chemical composition which constitutes the soils. It is found that the soil adsorption behavior of fluorescein can be prescribed in the Freundlich's adsorption equation. The adsorption behaviors on Kuroboku, Yellow brown forest and Peat are independent of the initial concentration of fluorescein and the mass ratio of soil to liquid. Although the adsorption behavior on Kanuma is dependent on the mass ratio of soil to liquid, the behavior could be represented by one Freundlich's adsorption equation if the mass ratio is constant.

Oral sodium fluorescein to improve visualization of clear vitreous during vitrectomy for proliferative diabetic retinopathy

To evaluate the efficacy and safety of orally administered sodium fluorescein to stain the clear vitreous before vitrectomy for proliferative diabetic retinopathy (PDR). Twenty-two consecutive eyes of 20 patients with PDR and five eyes of five patients with proliferative vitreoretinopathy (PVR) were included. The average patient age was 52 years (range 46-58). Closed pars plana vitrectomy, proliferative membrane peeling and endolaser photocoagulation were performed. Vitreous and blood samples were collected to measure sodium fluorescein concentrations by high pressure liquefied chromatography. The degree of staining of the clear vitreous was evaluated by colour photographs, videos and the concentration of sodium fluorescein in the vitreous and blood samples. The clear vitreous in all 22 eyes with PDR ranged from slightly to markedly green, but the clear vitreous in five eyes with PVR was not stained with sodium fluorescein. The sodium fluorescein concentration in the vitreous samples ranged from 122 to 282.0 ng/mL and from 64 to 74 ng/mL in the blood samples in patients with diabetes and PVR. No urticaria, nausea or other side-effects developed. The clear vitreous can be stained markedly green by sodium fluorescein administered 12-16 h before surgery. Surgeons can easily differentiate residual clear vitreous. The stained vitreous may be made more visible by photocoagulation. This method is also helpful in teaching surgical procedures, and fewer side-effects compared with intravenous and intravitreal fluorescein and intravitreal triamcinolone.

Transepithelial Transport of Folic Acid in Human Trophoblastic BeWo Cells

Transport of folate across the placental interface may be an important determinant of availability of maternal folate for proper embryonic development. The present aim was to develop a method for studying transepithelial folate transport across monolayers of human trophoblastic BeWo cells. To ensure the suitability of BeWo cells as a model for folate transport, we determined the expression of folate transport-related genes using real time PCR-based reverse transcription-PCR detection and found that transcripts for Folate Receptors α, β and γ and also Reduced Folate Carrier-1 were expressed. For transport studies, the apical surface of 14 day old BeWo cell monolayers maintained on (12 well dish) permeable membrane supports were exposed to transport buffer consisting of 200 nM of folic acid conjugated to rhodamine dye and equimolar concentration of sodium fluorescein (paracellular marker) dissolved in Hanks’ Balanced Salt Solution (HBSS) while the monolayer's basolateral side was bathed in HBSS, followed by sampling at various time points from basolateral chamber for fluorescence quantitation. The rate of transcellular transport of folic acid, calculated by subtracting the paracellular component from total folic acid-rhodamine transported, was 185 ± 24 femtomoles/minute/well in the apical (maternal) to basolateral (fetal) direction. Support: Young Investigator Award 2005, Spina Bifida Association of America.

Differential Stripping: Determination of the Amount of Topically Applied Substances Penetrated into the Hair Follicles

The determination of penetration pathways of topically applied substances into the skin is the subject of several investigations. Recently, follicular penetration has become a major focus of interest. To date, a direct, non-invasive quantification of the amount of topically applied substance penetrated into the follicles had not been possible. The development of such a method was the aim of this study. Therefore, the advantages of both stripping techniques, tape stripping and cyanoacrylate skin surface biopsy, were combined and evaluated. Tape stripping was used to remove the part of the stratum corneum that contained the topically applied dye. Subsequently, the follicular contents were ripped off by cyanoacrylate skin surface biopsy. The combined method termed "differential stripping" was evaluated in vitro and in vivo, and the amount of topically applied fluorescent dye penetrated into the hair follicles was quantified after different penetration times. After 30 min, 5% of the recovered concentration of sodium fluorescein was found in the follicular infundibula, where it was still detectable after 48 h. Altogether, the results of this investigation revealed that differential stripping is a new method that can be used to study the penetration of topically applied substances into the follicular infundibula non-invasively and selectively.

Sodium fluorescein as a retinal pH indicator?

Retinal neovascularization is a symptom associated with various diseases revealing ocular fundus manifestation. Often, these neovascularizations originate from retinal hypoxia. A concomitant phenomenon of hypoxia is acidosis. To recognise this would permit the identification and treatment of hypoxic fundus areas long before first vascular modifications are seen. Thus, the goal of this investigation was to elucidate whether sodium fluorescein could be used as a retinal pH indicator. Sodium fluorescein solution was diluted in PBS (ratio: 1:150 000). The pH was varied from 6.5 to 8.6 by supplementation of HCl or NaOH, respectively. The fluorescence was excited by a pulsed diode laser (wavelength: 446 nm, pulse width: 100 ps) and detected by time-correlated single photon counting (TCSPC) technique. A least-squares fit of the measured fluorescence decay versus time by an exponential function results in the fluorescence lifetime. Ten measurements were taken at each pH for statistical analysis. The dependence of the fluorescence lifetime on the temperature and the concentration of sodium fluorescein was investigated in the same way. The fluorescence lifetime was found to rise from 3.775 ns to 4.11 ns with increasing pH (6.5 to 8.6). However, the gradient decreases with increasing pH. We found highly significant differences (Student's t-test, P < 0.0005) of the fluorescence lifetimes for pH values with a mean difference of 0.125 at pH < 7.65 whereas the differences were still significant (P ⩽ 0.02) at pH > 7.65 and mean pH differences of 0.2. The fluorescence lifetime was independent of the temperature (22 °C to 37 °C) and the concentration of sodium fluorescein (dilution 1:150 000 to 1:2000). The fluorescence lifetime of sodium fluorescein depends on the pH but not on temperature and concentration. Thus, the discrimination of areas with retinal acidosis should be possible by combination of the TCSPC technique with scanning laser ophthalmoscopy. Further investigations have to clarify whether the accuracy of the measurement at the fundus in vivo is sufficient.

Characterization and in vivo evaluation of ocular bioadhesive minitablets compressed at different forces

The influence of the compression force on the physical properties, the in vitro release and the in vivo behavior of ocular minitablets is evaluated in the present study. The bioerodible minitablets (Ø 2 mm, 6 mg) were produced at different compression forces. The crushing strength, friability, water uptake, hydration and swelling of the minitablets both in vitro as well as in vivo after application in the cul-de-sac were evaluated. The friability remained below 1% only for the minitablets made at 0.500 and 0.750 kN. The crushing strength measured was 3.53±0.98, 12.34±1.69 and 18.64±2.37 N for minitablets made at 0.250, 0.500 and 0.750 kN, respectively. The full hydration time equalled 20 and 30 min for minitablets compressed at 0.250 kN and 0.500–0.750 kN, respectively. Increasing the compression force resulted in a decreased swelling capacity. The in vivo release was evaluated in healthy volunteers using a non-invasive method to measure the apparent sodium fluorescein concentration in the tearfilm–cornea compartment as a function of time. The longest residence time of the fluorescent tracer at the administration site was obtained by the minitablets compressed at 0.750 kN. The in vitro release was evaluated with three different dissolution methods: the reciprocating cylinder method, vials in an oscillatory shaking bath and a static method with vials. The best correlation with the in vivo behavior of the matrix minitablets was obtained with the shaking bath method.

Transport of a hydrophilic compound into the cerebrospinal fluid during experimental allergic encephalomyelitis and after lipopolysaccharide administration.

The transport of the hydrophilic model compound sodium fluorescein into the cerebrospinal fluid (CSF) of rats was studied during experimental allergic encephalomyelitis (EAE), as a model for local central nervous system (CNS) inflammatory disease, and after a single injection of a pyrogenic dose of lipopolysaccharide (LPS), as a model for a general inflammation. Transport of sodium fluorescein was measured by means of serial CSF and plasma sampling. Transport of this hydrophilic model compound was studied in Lewis rats suffering from EAA and three hours after LPS administration in male Wistar rats. During acute EAE, sodium fluorescein concentrations in the CSF increased twofold compared to control animals, whereas plasma kinetics were comparable within both groups. After i.v. LPS administration, however, plasma as well as CSF kinetic parameters of sodium fluorescein concentration were significantly changed from those seen in control animals. Transport of sodium fluorescein from plasma into the CSF was calculated as the ratio Area Under the Curve (AUC)CSF/AUCPLASMA. During acute EAE this ratio increased 2-fold compared to control animals, whereas after i.v. LPS administration it was not significantly different from the one obtained in control animals. These results suggest an opening of the blood-brain barrier (BBB) during a cerebral inflammatory response, like acute EAE, but not after LPS administration.

Shear rate and hematocrit dependence of fluorescence from retinal vessels in fluorescein angiography.

The purpose of this work was to obtain more quantitative knowledge about the yield of fluorescence from retinal vessels during fluorescein angiography. The influence of shear rate, concentration of sodium fluorescein, hematocrit, and layer thickness on the yield of fluorescence from blood were investigated. Measurements were performed in vitro on samples of human blood in a cone-plate shear chamber using frontal illumination. Application of physiologically relevant levels of shear (> 88/sec) decreased the yield of fluorescence from the blood sample considerably as compared with stasis. The yield of fluorescence was proportionally related to the logarithm of the sodium fluorescein concentration in blood up to a sodium fluorescein concentration of 1.2 mg/ml. Above that concentration quenching occurred. An increase in layer thickness at a hematocrit of 45% resulted only in an increase of the yield of fluorescence up to a layer thickness of 25 microns. In conclusion, the sodium fluorescein concentration in blood is the only important factor that determines the yield of fluorescence from the larger retinal vessels in the successive phases of the fluorescein angiogram in a subject with a given hematocrit and hemoglobin concentration. The yield of fluorescence from retinal vessels (> 25 microns) is proportionally related to the logarithm of the sodium fluorescein concentration over a broad range of concentrations.

Effects of peripheral cold exposure on microvascular dynamics in systemic sclerosis.

To determine the influence of cold exposure on microvascular permeability in systemic sclerosis (SSc). Thirteen patients with SSc were studied by dynamic fluorescence videomicroscopy under basal conditions and after exposure to cold. Exposure to cold caused a significant reduction in the interstitial concentration of sodium fluorescein (P < 0.05 to 0.001). Our findings show that cold exposure has a striking effect on microvascular dynamics in SSc.

Design and calibration of a low volume fog sampler

In this work a small, portable fog droplet sampler is presented. The modified low volume round jet impactor consists of a Teflon® inlet and a Teflon® cup as impaction surface, where the fog elements are collected, form bigger drops and then flow into a receiver vessel. The sampling apparatus has been designed in order to establish constant impaction conditions and a sharp cut-off at a droplet diameter of 10 μ, such conditions differentiating between fog droplets and non-activated aerosol particles. The apparatus has been calibrated with monodisperse DOP aerosol as a model for water droplets at a constant flow rate of 1.6 m 3 h −1. The calibration resulted in an effective cut-off diameter of 10.2 μm and a sharp cut-off characteristic. To verify if evaporation of the collected droplets or condensation of water vapour during sampling occurs, the impactor was tested with water droplets of well-defined sodium fluorescein concentration. The liquid collected in the recipient did not exhibit a statistically significant change in concentration. A field test in a dense fog showed that it is possible to collect a volume of fog-water sufficient for ion chromatographic analysis within 1 h.

Selecting optimal dosage volumes for eye irritation tests in the rabbit

AbstractThe elimination kinetics of sodium fluorescein applied into the conjunctival sac of the rabbit eye was studied at two dosages, 100 μl and 50 μl Tear samples were taken during the first 30 min after application. The concentration of sodium fluorescein in the sample was determined using high performance liquid chromatography with UV-VIS detector. The pharmacokinetic parameters were calculated on computer with the ESTRIP program. From the results of this study it can be concluded that the drainage kinetics of sodium fluorescein consist of a rapid and a slow phase. After application of 100 μl into the conjunctival sac of the eye, a time lag was observed before the concentration started to decrease in the eye. The time lag of 5–8 min observed at 100 μl disappeared when a volume of 50 μl was applied. This difference in time lag is indicative for the difference in eye toxicity, which has been observed between dosage volumes of 100 μl and 50 μl in earlier studies. The other pharmacokinetic parameters were...

Ophthalmic fluorophotometry: A new solid state fluorophotometer

A new low-voltage ophthalmic fluorophotometer is described. A solid state photodetector has been combined with a high-gain, low-noise amplification and synchronous detection system to develop a stable, relatively inexpensive instrument. Reliable measurements of sodium fluorescein concentration in the eye can be made down to 100 ng/ml (0.26 μmol/l) which allows the estimation of corneal permeability and tear flow rates. Preliminary measurements of tear turnover rate using the fluorophotometer are presented.

Fluorescence characteristics of sodium fluorescein in plasma and whole blood

The present study encompasses in vitro measurements of the excitation and emission spectra of thin layers of plasma and whole blood containing sodium fluorescein. Measurements were performed using frontal illumination of the sample: that is, the emitted fluorescence was measured from the side of the sample which was illuminated by the excitation light beam, thereby simulating the conditions of fundus angiography. The influence of sodium fluorescein concentration, layer thickness, hematocrit, and oxygen saturation of the blood on the fluorescence characteristics was investigated. The experimental results were compared with a theoretical analysis of the effect of absorption by blood on the fluorescence of sodium fluorescein diluted in blood.