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Effect of albumin binding on the hepatic transport of rose bengal: surface-mediated dissociation of limited capacity.

We have studied the steady-state removal of rose bengal by perfused rat livers to decide whether the tight association of this anion with albumin is consistent with the conventional view that only the free fraction in the sinusoidal lumen is available for hepatic transport. The results show that the concentration of free dye is not nearly high enough to account for the observed removal rate. From these observations we argue that the liver cell surface reduces the affinity of rose bengal for albumin by a factor of approximately 100 below that observed in free solution. The findings extend and refine the results of a similar experiment with taurocholate we reported previously and they confirm the suggestion by others that the dissociation mechanism displays saturation kinetics as the albumin concentration increases.

Animals↗

Importance of photo activation of rose bengal for platelet activation in experimental models of photochemically induced thrombosis.

Generation of oxygen free radicals in the lumen of a vessel leads to NO inactivation, modification of lipid components of platelets and endothelial cell membranes, and platelet activation. On this basis, many experimental models of thrombosis have been developed, where the formation of a platelet rich thrombus follows the illumination of a vessel with an appropriately filtered light after intravenous administration of Rose Bengal or another sensitizing dye. However the detailed mechanism of thrombus formation remains poorly known. This work appreciates the contribution of platelet activation directly induced by oxygen free radicals in formation of the platelet rich thrombus, from a study of human platelet aggregation in presence of photo-activated Rose Bengal. The results demonstrate that direct activation of platelets by free radicals generated by Rose Bengal is of low or no importance in formation of the thrombus. Therefore, the main trigger of platelet aggregation and thrombosis in these models is primary endothelial cells injury.

Fluorescent Dyes↗

The investigation of neonatal obstructive jaundice using 123I rose bengal.

With the development of new surgical techniques the outlook for infants with biliary atresia has improved significantly. It has therefore become increasingly important to identify these patients quickly in order to allow prompt surgical intervention. Differentiation of biliary atresia from other causes of jaundice, in particular idiopathic neonatal hepatitis, is often difficult as there is considerable clinical and histological overlap of the two conditions. Demonstration of biliary patency using radiopharmaceuticals is a well established technique. 131I rose bengal and the 99Tcm-labelled iminodiacetic acid derivatives have both been used, but are not completely satisfactory, and controversy still exists as to which is the most suitable agent. Nine infants with prolonged jaundice have been studied using 123I-labelled rose bengal. All infants with biliary atresia and neonatal hepatitis were correctly identified. The results indicate that 123I rose bengal provides a reliable tracer for assessing biliary patency and is the agent of choice in the investigation of neonatal obstructive jaundice.

Bile Ducts↗

131-I rose bengal liver scanning in the differential diagnosis of neonatal jaundice.

Results of a series of 2i liver scans with 131-I rose bengal in 21 patients who developed progressive jaundice in the neonatal period are described. Using the 131-I rose bengal scan alone, an attempt was made to separate the patients into two groups, the first with total bile obstruction (biliary atresia) and the second with only partial biliary tract obstruction (intrinsic liver disease). The diagnostic accuracy of the scan was 82%. An additional diagnostic criterion, the count radio, is suggested. The determination of this ratio requires no additional effort or expense and would improve the diagnostic accuracy of the scan used alone in this series of patients.

Biliary Tract↗

Photothrombosis of corneal neovascularization by intravenous rose bengal and argon laser irradiation.

Management of corneal neovascularization by photocoagulation has been limited and rarely successful. We evaluated the efficacy and safety of the novel technique of photothrombosis to occlude corneal neovascularization. Sixteen rabbit corneas with previous ocular surface wounds that had healed with 360 degrees extensive neovascularization (persistent for 20 months) were used. After an intravenous injection of rose bengal solution (40 mg/kg of body weight [BW]), each vessel on the upper half of the cornea was occluded with a photochemically induced thrombus within ten shots of argon laser irradiation (514.5 nm, 130 mW, 63 microns, 0.2 s); those on the lower half were used as an internal control. Throughout the four-month study period, the treated vessels remained occluded, as evidenced by corneal fluorescein angiography. Corneal clarity was improved after treatment. A single injection of rose bengal at a dose of 8 mg/kg of BW or higher was sufficient for successful photothrombotic occlusion of corneal vessels within one hour of experimentation. Transient elevations of serum urea nitrogen, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, and total bilirubin levels and decrease of serum phosphorus level were noted on the first day after injection with 40 mg/kg of BW of rose bengal solution.

Animals↗

Functional study with 131I-rose bengal in chronic active hepatitis and nonactive cirrhosis using a three-compartment model.

The authors, using 131I-Rose Bengal, determined the fractional transfer constants of a three-compartmental model in 30 patients divided into two groups (chronic active hepatitis and nonactive cirrhosis) on a histological basis. Other functional indexes were also taken into consideration. In nonactive cirrhosis, the results show a greater impairment of Rose Bengal transfer from plasma to liver. In chronic active hepatitis K32 (fractional transfer coefficient from the second to the third compartment) appears significantly lower than in nonactive cirrhosis. No significant differences have been found for K12 and K03. The best differentiation between the two groups (consistent with histological data in 29 of 30 cases) was obtained by grouping K21, retention index (RI) and SGOT in the discrimination function: L=4.88 K21-0.016RI+0.0034SGOT. The ratio K12/K21 seems meaningful for diagnostic purposes and in the evaluation of the hepatocellular damage in single cases.

Aspartate Aminotransferases↗

Inhibition of vesicular glutamate storage and exocytotic release by Rose Bengal.

It had been thought that quantal size in synaptic transmission is invariable. Evidence has been emerging, however, that quantal size can be varied under certain conditions. We present evidence that alteration in vesicular [(3)H]L-glutamate (Glu) content within the synaptosome (a pinched-off nerve ending preparation) leads to a change in the amount of exocytotically released [(3)H]Glu. We found that Rose Bengal, a polyhalogenated fluorescein derivative, is a quite potent membrane-permeant inhibitor (K(i) = 19 nM) of glutamate uptake into isolated synaptic vesicles. This vesicular Glu uptake inhibition was achieved largely without affecting H(+)-pump ATPase. We show that various degrees of reduction elicited by Rose Bengal in [(3)H]Glu in synaptic vesicles inside the synaptosome result in a corresponding decrease in the amount of [(3)H]Glu released in a depolarization- (induced by 4-aminopyridine) and Ca(2+)-dependent manner. In contrast, fluorescein, the halogen-free analog of Rose Bengal, which is devoid of inhibitory activity on vesicular [(3)H]Glu uptake, failed to change the amount of exocytotically released [(3)H]Glu. These observations suggest that glutamate synaptic transmission could be altered by pharmacological intervention of glutamate uptake into synaptic vesicles in the nerve terminal, a new mode of synaptic manipulation for glutamate transmission.

4-Aminopyridine↗

Modification of pig kidney diamine oxidase with ethoxyformic anhydride and rose bengal: evidence for essential histidyl residue at the active site.

Purified diamine oxidase from pig kidney showed time dependent inactivation by ethoxyformic anhydride and photooxidation with Rose Bengal. Modification of histidine either by ethoxyformic anhydride or by Rose Bengal was the sole cause of enzyme inactivation. The inactivated enzyme showed no significant perturbation in structure. The protection against photooxidation of enzymatic activity and histidine residues by inhibitor (phenylenediamine hydrochloride) and substrate (putrescine) protected the photooxidation of two histidyl residues. However, kinetic analysis of photooxidation of histidyl residues and inactivation of the enzyme conclusively suggested the involvement of one histidyl residue, which seems to be located at the active site of diamine oxidase.

Amine Oxidase (Copper-Containing)↗

The photodynamic effect of rose bengal on proteins of the mitochondrial inner membrane.

Photodynamic action promoted by Rose Bengal was evaluated in solutions of unsaturated fatty acids or histidine, and on beef heart submitochondrial particles. Rose Bengal-promoted photooxidation of histidine was mainly due to the opening up of the imidazole ring by singlet oxygen. Photosensitization of polyunsaturated fatty acids (PUFA) resulted in oxygen consumption and thiobarbituric acid-reactive substances (TBARS) formation, the extent of which was linearly related to the increasing degree of unsaturation. Photosensitization of submitochondrial particles caused oxygen consumption and TBARS production. These processes involved two different reaction components: during the first, most of the mitochondrial proteins were inactivated, the most sensitive being succinate dehydrogenase and cytochrome c. The values for the rate ratios of [TBARS] formation/[O2] consumption for the first and second phase were 0.36 and 1.32%, respectively, pointing to a larger contribution of lipid peroxidation during the second phase. The calculation of the rate constants for reaction of singlet oxygen with mitochondrial proteins suggests that singlet oxygen is more reactive towards proteins than to PUFA. The biological role of this selectivity is discussed in terms of the mitochondria as one of the first targets for photosensitized reactions.

Animals↗

Serial scintigraphy of choledochal cysts using 131I-rose bengal and 131I-bromsulphalein.

Nine cases of congenital choledochal cysts are reported which were correctly diagnosed by 131I-rose bengal or 131I-bromsulphalein (BSP) serial scintigraphy. They were classified by scintigraphic patterns into two types depending on whether biliary obstruction was complete or incomplete. All but two showed incomplete obstruction. The correct diagnosis may be difficult to make by scintigraphy if complete biliary obstruction is present. In such cases the clinical findings and other diagnostic studies, such as angiography or ultrasound, should be carefully considered. Serial scintigraphy with 131I-rose bengal or 131I-BSP is nontraumatic, safe, and provides increased diagnostic accuracy. It is the examination of choice when choledochal cysts are suspected clinically.

Adolescent↗

Evaluation of a modified Rose Bengal test and an indirect enzyme-linked immunosorbent assay for the diagnosis of Brucella melitensis infection in sheep.

A modified Rose Bengal test (mRB) and an indirect ELISA (iELISA) with Protein G as the conjugate, were evaluated for the diagnosis of Brucella melitensis infection in unvaccinated sheep with a known bacteriological status, and their diagnostic efficacy was compared with that of the standard Rose Bengal (RB) and Complement Fixation (CF) tests used in the current eradication campaign in EU countries. All tests showed 100% specificity when testing the sera from 212 Brucella-free sheep. When testing the sera from 219 Brucella melitensis culture-positive sheep, both the mRB and iELISA tests were more sensitive (98.6% and 96.8%, respectively) than the RB and CF tests (95.0% and 92.7%, respectively). These results were similar when testing the sera from 181 animals belonging to infected flocks but found bacteriologically negative, suggesting that the mRB or iELISA tests could advantageously replace the current RB procedure used as the screening test.

Animals↗

Interaction of nitric oxide with photoexcited rose bengal: evidence for one-electron reduction of nitric oxide to nitroxyl anion.

The interaction of nitric oxide (.NO) with Rose Bengal (RB) in the presence of electron donors was investigated. Upon illumination of a mixture of RB and .NO with visible light, an enhancement in the rate of .NO consumption was observed that increased with increasing RB concentration. In the presence of electron donors (NADH, glutathione, or ascorbate), the rates of .NO depletion increased further. NADH enhanced .NO depletion to a greater extent than either glutathione or ascorbate. Photoactivated RB under anaerobic conditions reacts with NADH to form the RB anion radical (RB.-), which has a characteristic visible absorption band centered at 418 nm. Rose Bengal anion radical disporportionates to give RB and a colorless reduced form of RB, RBH-. The net result of this process is the photobleaching of RB. The presence of .NO during irradiation of RB and NADH introduced a lag time into the kinetics of RB photobleaching. The length of this lag time was proportional to the concentration of .NO. A similar lag time, which was also dependent on the .NO concentration, was observed in the kinetics of formation of RB.-. The three-line electron spin resonance (ESR) spectrum of RB.-, with an intensity ratio 1:2:1, was obtained during irradiation of RB and NADH under anaerobic conditions. .NO introduced a concentration-dependent lag time into the kinetics of the appearance of this ESR signal. We propose that .NO oxidizes RB.- to regenerate RB and thus inhibit photobleaching until .NO is consumed. This reaction predicts the formation of NO-, the one-electron reduced form of .NO. Nitrous oxide, a characteristic dimerization product of NO-, was detected by gas chromatography. This evidence indicates the occurrence of a Type I mechanism between photoactivated RB and .NO.

Anions↗

Technetium-99m-pyridoxylideneglutamate, a new agent for gallbladder imaging: comparison with 131I-rose bengal.

Two agents used for hepatobiliary studies, 131I-rose bengal and 99mTc-pyridoxylideneglutamate, have been compared in rabbits. The 99mTc radiopharmaceutical is rapidly cleared from the blood by the liver and rapidly excreted through the common bile duct into the duodenum. Because of its rapid removal from the liver, visualization of the gallbladder and biliary passages was obtained within 15 min after injection in experimental animals.

Animals↗

Spectroscopic and electrochemical study of Rose Bengal in aqueous solutions of cyclodextrins.

The interaction of Rose Bengal (RB) in aqueous solution of LiClO4 0.1 M with alpha-cyclodextrin (alpha-CD), hydroxypropyl-beta-cyclodextrins (HP-beta-CD) and hydroxypropyl-gamma-cyclodextrins (HP-gamma-CD) were studied by spectrophotometric measurements. The presence of Induced Circular Signals and the results of the analysis of the modifications in the absorbance spectra of RB produced by the presence of CDs in solution indicate that RB forms inclusion complexes only with HP-beta-CD and with HP-gamma-CD.

Circular Dichroism↗

Hepatic storage and biliary excretion of rose bengal in the rat.

The distribution of intravenously administered rose bengal (RB) depends on its dose. At a low dose (10 mg/kg), RB can be found almost solely in the liver and plasma. However, at higher doses (from 25 up to 200 mg/kg) the amount of RB found in extra-hepatic tissues gradually increases. In this experiment the hepatic transfer maximum of RB amounted to 146 micrograms/kg/min. By increasing the dose from 10 to 200 mg/kg, the hepatic concentration of RB also approached a maximum (1250 micrograms/g). The storage capacity of the liver, however, did not limit the transfer maximum of RB.

Animals↗

Bovine brucellosis in the Highveld Region. 1. Effect of delay in transit on rose bengal test results.

Although the incidence of false negative rose bengal plate test (RBPT) results on sera which were delayed in transit for one to 17 days was greater than 0.65%, up to 7.2% of such reactions occurred in one infected herd. Since no correlation between the incidence of false negative RBPT results and delay in sera in transit could be found, it was postulated that this type of reaction should be attributed to animals in the early incubation stage of the disease or to individual variation in the rate of response to the RBPT; a problem which should resolve itself during consecutive tests. Blood samples taken from herds to be sold at sales or public auctions, however, should all be tested by the complement fixation test. No correlation between the serum agglutination test and complement fixation test results were noted except where serum agglutination test titres exceeded 134 IU ml-1.

Animals↗

Rose bengal positive epithelial microerosions as a manifestation of equine keratomycosis.

Purpose To describe the clinical appearance of corneal epithelial cell microerosions associated with keratomycosis in the horse. METHODS: Retrospective clinical study. RESULTS: Multifocal, punctate, superficial corneal opacities with positive rose bengal retention were noted in six horses with presumed 'viral keratitis'. Faint fluorescein staining was also present in three cases. Equine herpesvirus tissue culture inoculation was negative for a cytopathic effect in three cases. Aspergillus (n = 3), Curvularia (n = 1), and an unidentified fungus (n = 1) were cultured in five horses, and hyphae found on corneal cytology from the sixth. Mixed bacterial infections were present in three eyes. The eyes of two horses with Aspergillus progressed to deep melting corneal ulcers that required surgical therapy. The microerosions remained superficial, but persistent in the other four eyes. Natamycin was utilized topically in all six horses. Transmission electron microscopy from case 6 revealed mucin layer disruption, an intact corneal epithelial cell layer, and fungal attachment to degenerating epithelial cells. The visual outcome was positive in all six horses, although healing was prolonged (48.5 +/- 14.5 days on average in the horses with no surgery; 62 days on average in the two horses that required surgery). CONCLUSIONS: Complete removal or full-thickness penetration of the corneal epithelial cell barrier may not be necessary to allow fungal adherence and initiation of keratomycosis in the horse. Prior to colonization and invasion of the horse cornea, fungi may induce changes in the mucin layer of the tear film that result in or are associated with rose bengal positive microerosions of the superficial corneal epithelium. Horses with painful eyes, and eyes with superficial, multifocal corneal opacities should have their corneas stained with both fluorescein and rose bengal as fungal microerosions may stain weakly, or not at all, with fluorescein, and may thus be mistaken for presumed 'viral keratitis' of the horse.

Journal Article↗

Quantitative comparison of excited state properties and intensity- dependent photosensitization by rose bengal.

A quantitative (multistep) excitation-deactivation model of rose bengal (RB) has been developed which includes energy and electron transfer to oxygen and the possibility of photoproduct formation via higher excited triplet-singlet states. The model is based on previous measurements of non-linear absorption (NLA) and emission of RB with picosecond pulses at 532 nm and on NLA measurements with nanosecond pulses. A coupled rate equation and photon transport equation approach for non-linear light-matter interaction is used. The resulting term scheme with all relevant excited state parameters confirms that (i) in the first excited state of RB, relevant absorption at 532 nm takes place only in the triplet, and (ii) the previously reported intensity dependence of RB-sensitized enzyme inhibition is well modelled by the intensity-dependent RB-T1 population and (as the main process) subsequent energy transfer to form singlet oxygen.

Lasers↗