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PubMed1997

Electrical and mechanical modulations by oxygen-derived free-radical generating systems in guinea-pig heart muscles.

The effects of free-radical generating systems and angiotensin-converting enzyme (ACE) inhibitors on the action potentials and contractile force in guinea-pig cardiac muscles were examined using conventional microelectrode and whole-cell voltage-clamp methods at 36 degrees C. Hydrogen peroxide (30-100 microM) prolonged 50%, 75% and 90% repolarization of action-potential duration (APD) approximately 15-25 min after its application. But the longer exposure reversed the APD shortening in a concentration-dependent manner. Other action-potential parameters were not altered to a significant extent. The contractile force was increased. Longer exposure inhibited the enhanced force (but it was still larger than control). The effects on the spontaneous action potential from right atrial muscle were almost the same. In whole-cell voltage-clamp experiments, H2O2 (100 microM) inhibited L-type Ca2+ current and enhanced delayed rectifier K+ current. The effects of light-activated rose bengal (10-100 nM) on the APD were similar to, but more potent than, those of H2O2. The response was observed rapidly after a light illumination. During exposure to rose bengal (100 nM), abnormal spontaneous action potentials or arrhythmias such as a bigeminy occurred, presumably because of early and delayed afterdepolarizations. The responses were irreversible. At 300 microM ACE inhibitors, captopril and enalapril, protected the changes induced by these free radicals. These results indicate that H2O2 has a dual, time-dependent, action on the APD and rose bengal with light illumination produced the responses rapidly. The oxygen-derived free radicals increased [Ca]i and then cellular Ca2+ overload occurred. These responses were protected by ACE inhibitors.

Action Potentials↗
PubMed1976

Dissociation kinetics of complexes between the antibiotic rifamycin and DNA-dependent RNA polymerase from Escherichia coli.

Phosphocellulose chromatography was employed to measure the binding of 3-(2-[14C]acetamidoethyl)-thiorifamycin(abbreviated[14C]AcNHEtS-Rif) to RNA polymerase core enzyme. The technique yielded a correct value for the stoichiometry of interaction. The same method was successfully applied to an investigation of the dissociation kinetics of the [14C]AcNHEtS-Rif - core-polymerase complex. We observed biphasic dissociation kinetics not in agreement with the existence of one single first-order dissociation step. Assuming two independent dissociation reactions, rate constants have been evaluated differing roughly by 10-fold (1.7 X 10(-3) s-1 and 1.5 X 10(-4) s-1 at 25 degrees C). The ratio of the amplitudes of the biphasic dissociation kinetics changed with temperature. The kinetic data are interpreted as indirect evidence for the existence of two enzyme species differing in their dynamic properties with respect to the binding of the antibiotic rifamycin. Our data furthermore lend support to the assumption that the two enzyme forms are in equilibrium. The observed sigmoidal dependence of the dissociation rate on temperature could indicate a conformational transition of RNA core polymerase with a transition midpoint at around 20 degrees C. The dye, rose bengal, was found to be as effective as AcNHEtS-Rif itself as a competing agent. The dissociation kinetics of the [14C]-AcNHEtS-Rif - core-polymerase complex in the presence of an excess of the dye rose bengal were found to be very similar to those measured in the presence of AcNHEtS-Rif. This could mean that rose bengal and AcNHEtS-Rif compete for the same site at RNA core polymerase. The dissociation of the ternary complex [14C]AcNHEtS-Rif - core-polymerase - poly[d(A-T)] was followed by gel filtration. Up to the extent of dissociation measured, the reaction appeared to follow first-order kinetics. The dissociation rate constant was calculated to be 1.7 X 10(-4) s-1. Experiments to determine the effect of the antibiotic streptolydigin on the dissociation kinetics of the [14C]AcNHEtS-Rif - core-polymerase complex have not led to conclusive results.

Binding Sites↗
PubMed1990

Exacerbation of reperfusion arrhythmias by sudden oxidant stress.

A burst of free oxygen radical production has been demonstrated during the early moments of reperfusion, coincident with the onset of reperfusion arrhythmias, which can be attenuated by antioxidants. We have investigated whether a sudden burst of oxidant stress, superimposed on that occurring during reperfusion, can exacerbate reperfusion arrhythmias. Rat hearts (n = 12/group) were subjected to 12 minutes of aerobic perfusion; during the last 2 minutes, rose bengal (1 mumol/l) was added to the perfusion fluid. Then, regional ischemia was induced, and rose bengal-free perfusion was restored. After 5 minutes of ischemia, reperfusion was initiated for 5 minutes, and during the first 30 seconds of reperfusion, hearts were uniformly illuminated (8,500 lux) with green light (530-590 nm). The photoactivation of rose bengal trapped in the tissue, producing singlet oxygen and superoxide, resulted in an exacerbation of reperfusion arrhythmias. Thus, 92% of hearts developed ventricular premature beats, 83% ventricular tachycardia, and 33% ventricular fibrillation. In contrast, hearts with regional ischemia and reperfusion in the absence of rose bengal and/or illumination did not develop ventricular fibrillation; only one heart exhibited ventricular tachycardia, and the incidence of ventricular premature beats was lower (42-50%). Furthermore, the burst of oxidant stress shortened the time to onset of ventricular premature beats from 21.7 +/- 5.6 to 9.9 +/- 2.1 seconds. Additional studies revealed that rose bengal photoactivation without reperfusion was less arrhythmogenic compared with the combination of reperfusion plus photoactivation. These results demonstrate that a sudden burst of oxidant stress during the early moments of reperfusion can exacerbate the vulnerability to reperfusion arrhythmias.

Animals↗
PubMed1979

A study of inheritance in progressive intrahepatic cholestasis: hepatic excretory function in unaffected family members.

In an attempt to identify the heterozygotes state for progressive intrahepatic cholestasis (PIC), hepatic excretory function (131I rose bengal half-life (t1/2) and bromosulpthalein-transport maximum (BSP-Tm) was studied in controls and in eight members of a family, two of whom are affected with PIC. Values for 131I rose bengal t1/2 varied over a wide range in normal controls and were normal in patients with the syndrome of cholestasis and peripheral pulmonic stenosis in whom BSP-Tm and 45 min % retention were abnormal. 131I rose bengal t1/2 was abnormal in seven of eight family members. Despite this, BSP studies, including Tm, percent retention at 45 min, clearance were normal in all unaffected family members with the exception of the mother who has a reduced BSP-Tm. Fasting serum bile acid studies were normal in all unaffected family members. These studies do not clearly define the inheritance in this syndrome and suggest that any of the following three possibilities exist: 1) that the methods employed were not sensitive enough to detect heterozygotes, 2) that the inheritance in this syndrome is heterogenous; for instance, compound heterozygotes or autosomal dominant, or 3) that the family studies here represents a syndrome different from PIC.

Adult↗
PubMed1990

[An investigation of vital staining of the ocular surface and BUT of the tear film in Chinese].

Vital staining of the ocular surface with fluorescein and rose bengal and the tear film breakup time were studied in 268 healthy Chinese with the following results: Fluorescein did not stain the conjunctiva while it stained the cornea increasingly with age after 31 years. Rose bengal did not usually stain the cornea before the age of 30, the lacrimal caruncle and the semilunar fold before the age of 10, while it stained the bulbar conjunctiva of any age. BUT was 11-50 sec for 68.9% of the 268 subjects and the percentage less than or equal to 10 sec was 22.6%, which increased with age. The author concluded that rose bengal staining and BUT determination reflected the aging changes of the ocular surface and lacrimal secretion; however, for the Chinese, Rb staining of bulbar conjunctiva and BUT less than or equal to 10 sec alone should not be regarded as morbid.

Adolescent↗
PubMed1978

Vital staining properties of neutral red. Vital staining of cornea and conjunctiva.

Vital staining by instillation in the conjunctival sac of 1% neutral red in 54 normal and 153 differently affected eyes was studied by slit lamp examination. Of these, 134 eyes were after-stained by a mixture of 1% tetrazolium and 1/4% alcian blue and 73 eyes were after-stained by a mixture of 1% rose bengal and 1% fluorescein. Microscopy of a further 10 conjunctival scrapings and 40 mucous conjunctival threads disclosed neutral-red-stained inclusion bodies in the cytoplasm of the epithelial cells and the granulocytes. In the slit lamp the cornea and the conjunctiva were seen to be stained only rarely and, if so, poorly by neutral red, both in normal and affected eyes. Better staining was obtained with tetrazolium, and the best with rose bengal. The plica semilunaris, Marx' line, and the mucous thread were stained by neutral red, more intensely by rose bengal, and the least by tetrazolium. The inferior fornix and the tarsus were rarely stained by any of the three dyes. Neutral red seems to offer no diagnostic advantages over the vital stains with which the dye has been compared in the present study. More particularly we found no pathological processes that were stained more intensely by neutral red than by the other vital stains.

Cataract↗
PubMed1985

Inability of chemically generated singlet oxygen to break the DNA backbone.

The capacity of a photodynamic and a chemical source of singlet molecular oxygen to cause DNA strand breakage at pH 7.8 was compared in the following systems: (1) dissolved rose bengal plus light (400-660 nm), (2) a novel water-soluble naphthalene-derived endoperoxide showing temperature-dependent singlet oxygen release, in the absence of light. Covalently closed circular DNA was efficiently converted to the open (relaxed) form upon exposure to dissolved rose bengal plus light in a time-dependent reaction, showing that this system was capable of causing DNA strand breakage at pH 7.8. The reaction was greatly reduced under hypoxic conditions (less than 5 p.p.m. O2), was stimulated when using D2O instead of H2O as a solvent and was not inhibitable by superoxide dismutase, indicating that singlet oxygen was a critical intermediate. However, comparatively large fluxes of singlet oxygen generated by the endoperoxide completely failed to produce DNA strand breaks. We conclude that, although singlet oxygen seems to play a role in DNA strand breakage by rose bengal plus light, singlet oxygen per se is very inefficient if not completely incapable of causing DNA strand breakage.

DNA Damage↗
PubMed2004

Rebamipide increases the amount of mucin-like substances on the conjunctiva and cornea in the N-acetylcysteine-treated in vivo model.

PURPOSE: Rebamipide increases the amount of mucin-like substances in the stomach. We aimed to determine the effects of rebamipide on the amount of mucin-like substances in the conjunctiva and cornea of N-acetylcysteine-treated eyes. Furthermore, we attempted to evaluate the effects of rebamipide on the wound healing of N-acetylcysteine-treated eyes. METHODS: The model was created by instilling 10% N-acetylcysteine solutions into rabbit eyes. Rebamipide was then applied on the day following the completion of N-acetylcysteine treatment. The amount of mucin-like substances on the conjunctiva and cornea was measured using the Alcian-blue binding method. The degree of damage was evaluated using scores based on the areas and densities of the cornea and conjunctival after staining using a rose Bengal solution under blind conditions. RESULTS: Rebamipide increased the level of mucin-like substances on the conjunctiva of N-acetylcysteine-treated eyes when instilled at concentrations of 0.3% or higher, and 1% rebamipide increased the amount of mucin-like substances covering the cornea. Moreover, 1% rebamipide improved the rose Bengal scores of the cornea and conjunctiva in N-acetylcysteine-treated eyes. CONCLUSIONS: Rebamipide increased mucin-like substances on the cornea and conjunctiva of N-acetylcysteine-treated eyes. In accordance with the mucin-increasing effects, rebamipide improved the rose Bengal scores for the cornea and conjunctiva of N-acetylcysteine-treated eyes. However, the relevance of these findings to dry eyes is unclear because it is not known whether the change in mucus expression in the N-acetylcysteine model is similar to what occurs in aqueous tear deficiency. Consequently, it may be worth trying on an animal model of keratoconjunctivitis sicca.

Acetylcysteine↗
PubMed1979

Pharmacokinetics of hepatobiliary imaging agents in rats: concise communication.

The distribution and elimination kinetics of Tc-99m pyridoxlidene glutamate (Tc-99m PG), of Tc-99m N-(2,6-dimethyl-phenylcarbamoylmethyl) iminodiacetic acid (Tc-99m HIDA), and of I-131 rose bengal in blood were quantitated after i.v. injection in rats. This was performed by use of a unique indwelling catheter that externalizes the systemic circulation, permitting continuous monitoring of blood radioactivity. The blood activity-time curves of Tc-99m PG and Tc-99m HIDA are described by the sum of three exponential functions. Only two exponentials are required in the case of I-131 rose bengal. The rank order for the rates of loss from blood was Tc-99m HIDA less than Tc-99m PG less than I-131 rose bengal. Bile was collected after administration of Tc-99m HIDA and Tc-99m PG. The total excretion of radioactivity over a 70-min period amounted to 95.7% and 42.8% of the dose of Tc-99m HIDA and Tc-99m PG, respectively. A linear compartmental kinetic model was developed to account for the disappearance from blood and the biliary excretion of these radiopharmaceuticals in rats.

Animals↗
PubMed1991

Photochemically induced thrombosis model in rat femoral artery and evaluation of effects of heparin and tissue-type plasminogen activator with use of this model.

We report a new and reproducible model of thrombosis in the rat femoral artery. The thrombosis is initiated by endothelial injury subsequent to photochemical reaction between systemically injected rose bengal (10 mg/kg, i.v.) and transillumination of filtered xenon lamp (wave length: 540 nm) from the outside of the vessel. The blood flow of the femoral artery, which was monitored by a pulsed doppler flow meter, was fully stopped in 348.68 +/- 36.18 sec (n = 12) after i.v. injection of rose bengal under irradiation with green light. The formation of massive thrombosis was readily evident by visual inspection. The processes of primary endothelial injury and the subsequent formation of thrombosis during this manipulation were observed by light microscopy and analysed by the scanning and transmission electron microscopy. Pretreatment with heparin (30, 100 or 300 units/kg, i.v.) 10 min before rose bengal injection dose-dependently prolonged the time required to interrupt the blood flow. The thrombolytic activity of a tissue-type plasminogen activator (tPA) was also investigated. After the establishment of stable thrombotic occlusion of the femoral artery, infusion of tPA was started from the contralateral femoral vein for 30 min at the rate of 30 or 100 micrograms/kg/min. The occluded artery was reperfused in 2 out of 10 rats and in 9 out of 12 at the lower and higher rates of tPA infusion, respectively. That heparin could prevent the arterial occlusion and that tPA could reperfuse the occluded artery are observations consistent with the histopathological ones that the primary lesion of endothelium injured photochemically activates the platelet aggregation to form platelet-rich thrombus with extensions of erythrocyte-rich lesions. This model is expected to be a useful tool for evaluating the antithrombotic and thrombolytic agents.

Animals↗
PubMed2004

An inter-laboratory evaluation of selective media for the detection and enumeration of yeasts from blue-veined cheese.

Five countries representative of laboratories 1-5 evaluated 11 different selective media, designed to suppress mould and bacterial growth and support yeasts growth, for the recovery of yeast populations from blue veined cheeses. In addition, qualitative results were also incorporated. The yeast enumeration values were subjected to statistical analysis using analysis of variance (ANOVA) and the Tukey-Kramer multiple comparison test. With the exception of Laboratory 3, none of the other laboratories was successful in recovering yeasts on all the media. Six of the media proved inadequate for the enumeration of yeasts in the mould invested environment and were therefore omitted from statistical analysis. No significant differences in quantitative data obtained on Rose-Bengal Chloramphenicol Agar (RBCA), Dichloran Rose-Bengal Chloramphenicol Agar (DRBC), Dichloran 18% Glycerol Agar (DG18), and Malt extract agar supplemented with NaCl and oxytetracycline (MES) were detected by four of the collaborating laboratories whereas one laboratory found RBCA to be superior for yeast enumeration. DG18 and Malt Extract Agar with Biphenyl (MEB), however, were ranked superior based on qualitative results compared to the other media, attributed to distinctive individual yeast colonies and mould inhibition. RBCA, DRBC, DG18, and MES on the other hand, all proved to be adequate in supporting yeast colony development for quantitative analysis in samples obtained from blue veined cheeses.

Agar↗
PubMed1975

Effect of age on liver function.

Serum concentrations of bilirubin, alkaline phosphatase, and GOT as well as the retention of BSP and 131I-rose bengal were determined in 43 normal subjects over 50 years old for the purpose of evaluating age-dependent variations. The normalcy of the liver in all subjects was confirmed by biopsy. The values of serum bilirubin, alkaline phosphatase, and GOT were unaltered with increasing age. Age also had no effect on the retention of BSP and 131I-rose bengal, in contrast to some previous studies in which the normalcy of the liver was not satisfactorily established. No variations between the sexes were seen in our study. The median of the 45 minute BSP retention test was 4.2 percent, with a ninth decile of 7.5 percent. The median of the retention of 131I-rose bengal was 32 percent, with a ninth decile of 39.4 percent.

Aged↗
PubMed1988

[Evaluation of clinical symptoms and laboratory data as diagnostic criteria for Sjögren's syndrome].

In this study the authors evaluated the sensitivity, specificity and misclassification error rate of the following parameters: subjective xerophthalmia (questionnaire), positive Schirmer's I test less than or equal to 5 mm/5 min, positive rose-bengal staining on slit lamp examination, subjective xerostomia (questionnaire), abnormal stimulated parotid flow rate less than or equal to 0.5 ml/5 min and recurrent parotid gland enlargement. Thirty-two patients with primary SS (pSS), 40 patients with some of the criteria for pSS, 20 patients with SS in association with RA (sSS), 45 patients with RA and some of SS criteria and 29 RA patients without any clinical or histological manifestations of SS participated in this study. The minor salivary gland histopathology (focal lymphocytic infiltrates greater than or equal to 2+ (T. M. Tarpley et al., 1972) was taken as prerequisite for the diagnosis of SS and the absence of any clinical or serological manifestations of other autoimmune disease for the diagnosis of pSS. Based on this analysis the authors suggested that definite pSS can be diagnosed in the absence of any other autoimmune disease, positive labial biopsy and the presence of subjective xerostomia or parotid gland enlargement or positive rose-bengal staining, and definite sSS if a patient has RA, positive labial biopsy and subjective xerophthalmia or positive rose-bengal staining.

Diagnosis, Differential↗
PubMed1991

Singlet oxygen induced cerebral vasospasm: an experimental study in rats.

A new experimental model is described which can be used as an alternative to study the effects of subarachnoid hemorrhage (SAH) in rats. Vasospasm of the basilar artery is induced photochemically after transpalatal illumination of intracisternally injected rose bengal in two different rat strains. Singlet oxygen, generated in the subarachnoid space, elicits vasospasm which has been demonstrated angiographically at 90 min and 24 h after photosensitisation. Sprague Dawley rats responded better than Wistar rats. Dilution of rose bengal in water was more vasospastic than dilution of rose bengal in artificial CSF. Since the action of singlet oxygen is similar to that of free radicals, this experiment gives an argument for the hypothesis that free radicals play a leading role in the pathogenesis of cerebral vasospasm after subarachnoid hemorrhage.

Animals↗
PubMed1995

Vessel wall injury and arterial thrombosis induced by a photochemical reaction.

Arterial thrombosis may be initiated in an experimental animal by a photochemical reaction between transmural green light and i.v. administered Rose Bengal, a photosensitizer dye. In this study, scanning electron microscopy has been used to reveal the nature of vessel injury and the cellular composition of the photochemically induced thrombus. A 5 mm segment of the guinea pig femoral artery was occluded by a thrombus about 10 min after irradiation with green light in the presence of systemically administered Rose Bengal. Electron microscopy revealed that following photochemical reaction, endothelial cells first contract and, with further irradiation, become detached from the vessel wall, with their cell membrane being destroyed at the irradiated site where an occlusive platelet-rich thrombus was formed. Endothelial cell injury and vessel occlusion could be completely inhibited by the aminothiol, DL-cysteine administered i.v. 1 min after Rose Bengal. The mechanism of endothelial injury in this model appears to be by singlet molecular oxygen, 1O2 formed by energy transfer from the photo-excited dye to O2.

Animals↗
PubMed2005

[Tear film analysis and its relation with palpebral fissure height and exophthalmos in Graves' ophthalmopathy].

PURPOSE: To evaluate tear film quality by rose bengal staining and its stability by breakup time, relating with palpebral fissure height and exophthalmos in patients with Graves' ophthalmopathy. METHODS: We studied 54 eyes of 27 patients with Graves' ophthalmopathy, either in the inflammatory or in the chronic phase of the disease. The evaluation consisted of tear film qualitative analysis by rose bengal staining using the van Bijsterveld grading scale, tear film stability analysis by breakup time, measurement of palpebral fissure height and exophthalmometry. Qui square test was used to perform statistical analysis. RESULTS: Among 27 studied patients, 77.8% were females and 22.2% males. Mean age was 44.26 years (SD 12.67). Mean disease time was 5.85 years (SD 4.47) and mean ophthalmopathy time was 5.81 years (SD 5.37). Among 54 studied eyes, 37% had positive test by van Bijsterveld's grading scale, 33.3% tear film breakup time lower than 5 seconds, 57.4% palpebral fissure height greater than 11 mm and 55.6% exophthalmometry greater than 19 mm. When relating tear film breakup time lower than 5 seconds with palpebral fissure height greater than 11 mm we found an odds ratio of 11.2 (p=0.0008). The remaining relationships did not show statistical significance. CONCLUSIONS: Dry eye diagnosed by rose bengal staining and tear film breakup time occurs frequently in Graves' ophthalmopathy. Palpebral fissure height correlates with tear film breakup time in Graves' ophthalmopathy. Its increase may lead to tear film instability.

Adult↗
PubMed1991

Photodynamic retinal vascular thrombosis. Rate and duration of vascular occlusion.

Dye-sensitized photochemical thrombosis is a new method of producing vascular occlusion in the eye for experimental purposes. The rate and duration of photodynamic occlusions of branch retinal vessels was measured in pigmented and albino rat eyes after intravenous injection of the photosensitizing dye, rose bengal. Selected vessels were exposed to focused, white light until vascular occlusion was observed biomicroscopically. A slit lamp was used for a light source in this procedure, allowing adjustment of spot size, shape, and orientation. Arterioles occluded more rapidly than venules, and the time required to produce vascular occlusion decreased when animals breathed pure oxygen administered by face mask. Rose bengal doses of 40 and 80 mg/kg were effective, 20 mg/kg was partially effective, and 1 and 10 mg/kg were ineffective in producing branch arteriole occlusion at a light intensity of 73.5 mW/cm2. The total light energy required to produce occlusion increased from an average of 0.06 J using 80 mg/kg to 0.50 J using 20 mg/kg of rose bengal. Lower light intensities produced vessel occlusion less rapidly (46 mW/cm2) or not at all (17.5 mW/cm2). The rate of retinal arteriolar occlusion was not affected by ocular pigmentation. The duration of branch vessel occlusion depended on length of vessel treated and did not exceed 3 days in arterioles and 4 days in venules. Histologic sections showed discrete areas of retinal and choroidal vascular thrombosis confined to the area of direct light exposure. Choroidal vascular thrombosis and outer retinal damage predominated in eyes treated at low light intensity. Thrombosis usually extended into the deep choroidal vessels in albino but not pigmented eyes.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1999

Inhibition of human aldehyde reductase by drugs for testing the function of liver and kidney.

Drugs for testing the function of liver and kidney (sulfobromophthalein, phenolsulfonphthalein, indigo carmine and indocyanine green) and other organic anions (rose bengal and haematin) were found to potently inhibit human liver aldehyde reductase that is involved in the detoxification of 3-deoxyglucosone and methylglyoxal, reactive intermediates, during the formation of advanced glycation end products. The inhibition patterns by the compounds were non-competitive with respect to both coenzyme (NADPH) and substrate (D-glucuronate). The kinetics of the inhibition by a mixture of the 2 inhibitors suggests that all the inhibitory compounds bind to overlapping sites on the enzyme. The binding of rose bengal, sulfobromophthalein and phenylsulfonphthalein to the free enzyme was detected by ultrafiltration assay. However, in the reverse reaction, the enzyme was inhibited competitively with respect to the alcohol substrate by rose bengal, haematin, phenolsulfonphthalein, sulfobromophthalein, indigo carmine and indocyanine green, which showed Ki values of 0.1, 1, 3, 4, 4 and 10 microM, respectively. The results suggest that these potent inhibitors bind weakly to the free enzyme and tightly to the enzyme-NADP binary complex.

Aldehyde Reductase↗