Cytotoxicity of dental disclosing solution on gingival epithelial cells in vitro.

OBJECTIVE: Coloring dental biofilm and plaque with a dental disclosing solution is visually effective in dental treatment and oral hygiene education. Despite continuous reports of the risk of the product ingredients, dental disclosing solution are widely used in dentistry. However, the cytotoxic mechanism of dental disclosing solution is not known. Here we elucidated the tissue dyeing range and investigated the cytotoxic mechanism of dental disclosing solution. MATERIALS AND METHODS: Gingival epithelial cells and mouse head and neck tissue were stained with dental disclosing solution. Changes in the cell cycle distribution by the dental disclosing solution treatment were analyzed. A deoxynucleotidyl transferase dUTP nick and labeling (TUNEL) assay was performed to examine the apoptotic features of the gingival epithelial cells. RESULTS: Dental disclosing solution stained the chromosome strongly, as well as both the hard and soft tissue of the mouse head and neck. The results of flow cytometric analysis and TUNEL analyses revealed that the cytotoxicity associated with dental disclosing solution was related to the induction of apoptosis. However, the staining of porcine skin by dental disclosing solution was not easily removed, even with a wide range of pH solutions. CONCLUSIONS: These results suggest that dental disclosing solution had strong cytotoxicity and safer alternatives are needed.

Antimicrobial effect of photodynamic therapy using erythrosine/methylene blue combination on Streptococcus mutans biofilm.

BACKGROUND: Photodynamic therapy (PDT) has demonstrated promising results in the treatment of several clinical pathologies through the photochemical reaction caused by the combination of a photosensitizer and a light source. The objective of this study was to evaluate the antimicrobial effect of the combination of the photosensitizers (PSs) erythrosine/methylene blue activated by a white halogen light device on Streptococcus mutans biofilm. METHODS: Two separate experiments were conducted, the first using the PSs at the concentration of 100 µM, and the second 250 µM. The PSs were tested on S. mutans biofilms cultured for 24 h in isolation, in combination, with and without light activation for 2 min fractionated in 4 periods of 30 s. After treatment, biofilms were diluted and plated on BHI medium and incubated for 24 h for colony forming units (CFU) counting. The results (log10) were analyzed with ANOVA followed by Tukey test (p < 0.05). RESULTS: The erythrosine/methylene blue combination activated by white halogen light at 100 and 250 µM, and erythrosine at 250 µM, methylene blue at 250 µM presented significantly reduced cell counts (3.2 log10, 5.3 log10, 4.5 log10, 4.3 log10, respectively) when compared to controls (p < 0.05). CONCLUSION: PDT with the combination of erythrosine/methylene blue demonstrated better results that the PSs in isolation regardless of the concentration. The use of this combination at the concentration of 250 µM shows promise as an antibacterial treatment for carious lesions and should be further assessed.

Immobilization of triclosan and erythrosine in layer-by-layer films applied to inactivation of microorganisms.

The use of layer-by-layer (LbL) deposition technique allows materials, such as drugs, to be self-assembled in multilayers with other electrolytes by combining their properties in a nanostructured system. Triclosan (TCS) is commonly used as a drug because of its bactericidal action, while erythrosine (ERY) has been used as a photosensitizer in photodynamic therapies because of its high light absorptivity in the visible region of the electromagnetic spectrum. The major advantage of investigating systems immobilized in LbL films is the benefit of characterizing the interaction through available substances in solid state techniques. It was possible to immobilize in LbL films, ERY, and ERY + TCS. The results show that the growth of the films was linear, indicating the deposition of the same amount of material from the first bilayer without substrate interference. The release analysis showed slow kinetics, which occurred more rapidly for ERY LbL films, probably due to apparent activation energy, which were higher for films with TCS. The combination of TCS, ERY, and laser light (532 nm) for photodynamic inactivation of the fungus Candida albicans was analyzed, and the results were promising for future studies in applications, such as coating surfaces of dental implants.

Singlet oxygen production by combining erythrosine and halogen light for photodynamic inactivation of Streptococcus mutans.

BACKGROUND: Photodynamic inactivation of microorganisms is based on a photosensitizing substance which, in the presence of light and molecular oxygen, produces singlet oxygen, a toxic agent to microorganisms and tumor cells. This study aimed to evaluate singlet oxygen quantum yield of erythrosine solutions illuminated with a halogen light source in comparison to a LED array (control), and the photodynamic effect of erythrosine dye in association with the halogen light source on Streptococcus mutans. METHODS: Singlet oxygen quantum yield of erythrosine solutions was quantified using uric acid as a chemical-probe in an aqueous solution. The in vitro effect of the photodynamic antimicrobial activity of erythrosine in association with the halogen photopolimerizing light on Streptococcus mutans (UA 159) was assessed during one minute. Bacterial cultures treated with erythrosine alone served as negative control. RESULTS: Singlet oxygen with 24% and 2.8% degradation of uric acid in one minute and a quantum yield of 0.59 and 0.63 was obtained for the erythrosine samples illuminated with the halogen light and the LED array, respectively. The bacterial cultures with erythrosine illuminated with the halogen light presented a decreased number of CFU mL(-1) in comparison with the negative control, with minimal inhibitory concentrations between 0.312 and 0.156mgmL(-1). CONCLUSIONS: The photodynamic response of erythrosine induced by the halogen light was capable of killing S. mutans. Clinical trials should be conducted to better ascertain the use of erythrosine in association with halogen light source for the treatment of dental caries.

A study of the control of oral plaque biofilms via antibacterial photodynamic therapy.

AIM: The aim of this study was to provide preliminary data on the most effective erythrosine concentration and light dose for the erythrosine-based photodynamic therapy (PDT) of oral plaque biofilms formed in vivo. METHOD: A randomised controlled study with 15 volunteers was carried out to investigate the effect of photo-sensitiser and light dose on the killing of bacteria in oral plaque biofilms formed in vivo. All volunteers wore a removable in situ appliance carrying six enamel slabs for two phases of 2 weeks each. During this time, plaque biofilms accumulated on the enamel slabs. The slabs were then removed from the appliances for PDT treatment in vitro. In the first phase of the study, erythrosine doses of 22 and 220 µM were used for the photodynamic treatment of the biofilms. In the second phase, the erythrosine concentration was kept constant, and the light dose was varied. Following treatment, the biofilms were disaggregated, and the total bacterial killing was determined using colony counting. RESULTS: The erythrosine dose of 220 µM caused the most cell killing relative to controls. Fifteen minutes of continuous irradiation with light and light fractionation of 5 × 1 min irradiation separated by 2-min-dark recovery periods were found to be the most effective bactericidal regimes. CONCLUSION: Erythrosine-based PDT shows promise as an antibacterial treatment for oral plaque biofilms. Further research is needed to prove its clinical and cost-effectiveness compared with current best practice.

Development and characterization of erythrosine nanoparticles with potential for treating sinusitis using photodynamic therapy.

BACKGROUND: Antimicrobial therapy for sinusitis has been shown to reduce or eliminate pathologic bacteria associated with rhinosinusitis and improve the symptoms associated with the disease. However, the continuing rise in antibiotic resistance, the ongoing problem with patient compliance, and the intrinsic difficulty in eradication of biofilms complicates antibiotic therapy. The introduction of photodynamic antimicrobial therapy (PAT) using erythrosine, a photosensitizer, could eliminate the bacteria without inducing antibiotic resistance or even requiring daily dosing. In the present study, erythrosine nanoparticles were prepared using poly-lactic-co-glycolic acid (PLGA) and evaluated for their potential in PAT against Staphylococcus aureus cells. METHODS: PLGA nanoparticles of erythrosine were prepared by nanoprecipitation technique. Erythrosine nanoparticles were characterized for size, zeta potential, morphology and in vitro release. Qualitative and quantitative uptake studies of erythrosine nanoparticles were carried out in S. aureus cells. Photodynamic inactivation of S. aureus cells in the presence of erythrosine nanoparticles was investigated by colony forming unit assay. RESULTS: Nanoprecipitation technique resulted in nanoparticles with a mean diameter of 385nm and zeta potential of -9.36mV. Erythrosine was slowly released from nanoparticles over a period of 120h. The qualitative study using flow cytometry showed the ability of S. aureus cells to internalize erythrosine nanoparticles. Moreover, erythrosine nanoparticles exhibited a significantly higher uptake and antimicrobial efficacy compared to pure drug in S. aureus cells. CONCLUSION: In conclusion, erythrosine-loaded PLGA nanoparticles can be a potential long term drug delivery system for PAT and are useful for the eradication of S. aureus cells.

Biomimetic nanocrystalline apatites: Emerging perspectives in cancer diagnosis and treatment.

Nanocrystalline calcium phosphate apatites constitute the mineral part of hard tissues, and the synthesis of biomimetic analogs is now well-mastered at the lab-scale. Recent advances in the fine physico-chemical characterization of these phases enable one to envision original applications in the medical field along with a better understanding of the underlying chemistry and related pharmacological features. In this contribution, we specifically focused on applications of biomimetic apatites in the field of cancer diagnosis or treatment. We first report on the production and first biological evaluations (cytotoxicity, pro-inflammatory potential, internalization by ZR-75-1 breast cancer cells) of individualized luminescent nanoparticles based on Eu-doped apatites, eventually associated with folic acid, for medical imaging purposes. We then detail, in a first approach, the preparation of tridimensional constructs associating nanocrystalline apatite aqueous gels and drug-loaded pectin microspheres. Sustained releases of a fluorescein analog (erythrosin) used as model molecule were obtained over 7 days, in comparison with the ceramic or microsphere reference compounds. Such systems could constitute original bone-filling materials for in situ delivery of anticancer drugs.

Short-term erythrosine B-induced inhibition of the brain regional serotonergic activity suppresses motor activity (exploratory behavior) of young adult mammals.

Previous studies showed that repeated ingestion of erythrosine B (artificial food color) developed behavioral hyperactivity, but nothing is known about its single administration effect as well as the neurochemical (s) involvement. The present study provides evidence that a single higher dosage (10, 100 or 200 mg/kg, p.o.) of erythrosine administration to young adult male rats reduced motor activity (MA) maximally at 2 h and brain regional (medulla-pons, hippocampus and hypothalamus) serotonergic activity (measuring steady-state levels of 5-HT and 5-HIAA, pargyline-induced 5-HT accumulation and 5-HIAA declination rate and 5-HT receptor binding) under similar experimental condition. The degree of erythrosine-induced inhibition of both MA and brain regional serotonergic activity was dosage dependent. Lower dosage (1 mg/kg, p.o.) did not affect either of the above. Erythrosine (100 or 200 mg/kg, p.o.)-induced MA suppression was also observed in the presence of specific MAO-A inhibitor, clorgyline (5 mg/kg, i.p.) or MAO-B inhibitor, deprenyl (5 mg/kg, i.p.); but their co-application (5 mg/kg, i.p., each) effectively prevented the erythrosine-induced motor suppression. Altogether these results suggest that a single higher dosage of erythrosine (10-200 mg/kg, p.o.) may reduce MA by reducing serotonergic activity with modulation of central dopaminergic activity depending on the brain regions.

Suitable conditions for sealing of open dentinal tubules using a pulsed Nd:YAG laser.

UNLABELLED: BACKGROUND DATA AND OBJECTIVES: Nd:YAG laser radiation has been applied in treatment of dentine hypersensitivity; dentine melt created after irradiation on a tooth surface can occlude open dentinal tubules. Different conditions (energy of pulses, number of successive irradiations, and type of dye agent) have been reported in the literature. In our study, different conditions are compared and the most suitable ones are suggested. METHODS: One hundred nine dentine samples prepared from extracted human third molars in the form of 2- or 3-mm thick discs and facets from an outer convex surface of a root were irradiated by pulses with duration 0.3 ms and beam diameter 0.3 or 0.6 mm. The laser repetition rate was 15 Hz. Energies per pulse have been changed from 20 mJ to 250 mJ (the corresponding energy densities rho are 22 and 275 J/cm(2) for the beam diameter of 0.3 mm). Dyes including tartrazine, carmine indigo, erythrosin, and methylene blue have been used to cover dentine surfaces and to increase absorption of laser radiation. Irradiated dentine surfaces have been investigated using scanning electron microscopy. RESULTS: Sealing of open dentinal tubules can be accomplished even without dyes, provided that a sufficiently intense laser radiation level is used. To avoid damage to the dentine's surface the use of dyes is necessary. Erythrosin has been found to be the best agent, and closing of dentinal tubules occurred after four doses of irradiation with 30-mJ pulses with a beam diameter of 0.6 mm (energy density rho = 8.25 J/cm(2), total energy density rho(T) = 33 J/cm(2)). The upper limit has been reached using four doses of irradiation by 90-mJ pulses with a beam diameter of 0.3 mm (rho = 99 J/cm(2), rho(T) = 396 J/cm(2)). CONCLUSIONS: Occluding dentinal tubules can safely and effectively be accomplished using pulsed Nd:YAG laser radiation provided that the dentine surface is covered with erythrosin solution.

Optimal rinsing time for intra-oral distribution (spread) of mouthwashes.

AIM: To investigate the intra-oral spread of an erythrosine mouthwash in relation to the rinsing period. MATERIAL AND METHODS: Thirty subjects were randomly divided into two equal groups and asked to rinse with 10 ml erythrosine mouthwash for cumulative periods of 15, 30 and 60 s (Group I) and 30, 60 and 90 s (Group II). Each rinsing session was followed by new plaque measurements. After rinsing plaque was finally assessed using the erythrosine mouthwash applied by means of a cotton swab. RESULTS: In Group I there was a difference observed between the 15 s rinsing period and those of 30 and 60 s. Explorative analysis for Group I suggested that differences in both jaws and approximal sites on both vestibular and lingual surfaces appeared to have contributed to the overall difference seen between 15 and 30 s rinsing periods. Also, pre-molars and front teeth seem to have contributed to this observed difference. No differences were noted between rinsing sessions and cotton swab application for Group II or Groups I+II combined. CONCLUSIONS: Rinsing for 30 s appeared to be sufficient for all plaque-covered surfaces of the dentition to come into contact with the mouthwash.

Assessment of the influence of energy under-reporting on intake estimates of four food additives.

Under-reporting has been identified as an important source of uncertainty in food chemical exposure assessments. The objective of the present study was to assess the influence of under-reporting on food additive intake estimates. Dietary survey data were derived from the North-South Ireland Food Consumption Survey (2001). Data from the Republic of Ireland (n = 958) were used. Energy under-reporters were identified using a ratio of energy intakes to estimated basal metabolic rate. First, food categories (n = 26) included in an assessment of exposure of four food additives were created and patterns of food intakes (i.e. likelihood of consumption, frequency of consumption and reported portion size) between acceptable and under-reporters compared. Second, for each food additive, deterministic intake estimates for the total sample (i.e. acceptable and under-reporters), under-reporters and acceptable reporters were calculated and compared. Differential reporting of the majority of food categories between acceptable and under-reporters was recorded. Under-reporters were less likely to record the consumption of a given food and more likely to under-report the frequency of consumption and portion size compared with acceptable reporters. Food additive intake estimates amongst acceptable reporters were higher than corresponding intake estimates amongst the total sample of reporters and amongst under-reporters. With the exception of one food additive (erythrosine), ratios of upper percentile additive intakes amongst acceptable reporters to corresponding intake estimates amongst the total sample of reporters did not exceed 1.06 when results were expressed as total population or consumer-only intakes. Findings illustrated that energy under-reporting does not materially influence estimates of food additive exposure based on the four food additives studied. However, a number of situations were identified where the under-reporting might exert a more significant impact on resulting exposure estimates.

Reproductive and neurobehavioural toxicity study of erythrosine administered to mice in the diet.

Erythrosine was given in the diet to provide levels of 0 (control), 0.005, 0.015 and 0.045% from 5 weeks of age of the F(0) generation to 9 weeks of age of the F(1) generation in mice, and selected reproductive and neurobehavioural parameters were measured. There were no adverse effects of erythrosine on either litter size, litter weight or sex ratio at birth. The average body weight of the offspring was significantly increased in the middle-dose group in both sexes during the lactation period. In behavioural developmental parameters, any variables showed no significant adverse effects in either sex in the lactation period. In movement activity of exploratory behaviour, several parameters were significantly changed in the high-dose group, and those effects were dose related in adult females in the F(0) and F(1) generations and in male offspring in the F(1) generation. The dose level of erythrosine in the present study produced few adverse effects in reproductive and neurobehavioural parameters in mice.

An assessment of the in vivo clastogenicity of erythrosine.

In an investigation of the in vivo clastogenic potential of the food colouring erythrosine (ER), male B6C3F1 mice were treated by ip injection at doses of 50, 100 and 200 mg/kg, repeated 24 hr apart. Signs of toxicity were observed at the highest dose of ER administered. The three cytogenetic endpoints analysed were sister chromatid exchanges (SCEs) in peripheral blood lymphocytes (PBLs), micronuclei in bone marrow polychromatic erythrocytes (PCEs), and micronuclei in peripheral blood reticulocytes (PBRs). SCE frequencies in PBLs were 4.13, 4.58, 4.33 and 4.60 SCE/cell at 0, 50, 100 and 200 mg ER/kg, respectively. At the same doses, the frequencies of micronucleated PCEs were 3.5, 3.2, 2.0 and 2.5/1000 PCEs. Micronuclei in PBRs ranged from 1.2 to 3.6 and from 1.4 to 3.0/1000 PBRs in control and treated mice, respectively. These results indicate that ER is inactive as a clastogen in mouse blood and marrow cells. This result supports the hypothesis of a non-genotoxic mechanism for ER carcinogenicity.

Teratogenic potential of FD&C Red No. 3 when given by gavage.

FD&C Red No. 3 (erythrosine) is a commonly used food additive. As part of a series of studies on the potential fetal developmental effects of food colors, FD&C Red No. 3 was administered by gavage to pregnant Osborne-Mendel rats at daily dose levels of 15, 30, 100, 200, 400, or 800 mg/kg on days 0-19 of gestation. Control animals were given distilled water by gavage. On gestation day 20, the animals were euthanized and cesarean sections were performed. During the entire treatment period, feed consumption by the animals given 400 mg/kg doses was increased significantly; the increases in the animals given 30 or 800 mg/kg were of borderline significance. The only significant increase in maternal weight gain, on days 0-7 in the animals given 30 mg/kg, was considered a random occurrence. No dose-related changes were seen in maternal clinical findings, implantations, fetal viability, or fetal size (weight and length). No fetal terata were seen, and neither skeletal nor visceral development was affected. FD&C Red No. 3 was neither fetotoxic nor teratogenic at 800 mg/kg when given by gavage.

Case study: erythrosine.

Erythrosine (FD & C Red No. 3) is an iodine-containing food colour which was used as an example in the application of the proposed approach of data-derived safety factors. The effect of erythrosine on the thyroid and the mechanism by which the effect is induced has been central to the discussion of the establishment of an Acceptable Daily Intake (ADI), or not, and a short account is given of the effect of erythrosine on the thyroid. The evaluation of erythrosine as a secondary tumorigenic agent was based on the evaluations of the Joint FAO/WHO Expert Committee on Food Additives (JECFA) and the Scientific Committee for Food of the Commission of the European Communities (SCF). In the proposed decision tree scheme, three different possibilities were examined. One was based on the long-term data and the second on the hormone data in the rat; the third was based on the NOEL for hormonal changes in humans. The three approaches with different NOEL and default values resulted in the following ADIs: 0.25, 0.3 and 0.1 mg/kg bw. The cases are discussed and it is concluded that the ADI based on the NOEL in human studies seems most appropriate. As there is most uncertainty about the default value for human pharmacokinetic variability, it is suggested that further human studies might elucidate this point.

Teratogenic potential of FD & C red no. 3 when given in drinking water.

FD & C Red No. 3 (erythrosine), a commonly used food additive, was administered to pregnant Osborne-Mendel rats to study its teratogenic potential. Dosing solutions of 0.05, 0.1, 0.2 or 0.4% in distilled water were available at all times and corresponded to daily doses of 64, 121, 248 and 472 mg FD & C Red No. 3/kg body weight. Distilled water served as the control. On gestation day 20, the animals were killed and caesarean sections were performed. The treated animals consumed less fluid than did the control animals, but only random decreases were statistically significant and no dose relationship was seen. Only the 0.2% group consumed significantly more feed than the controls during gestation. Maternal weight gain during days 0-20 was not significantly affected in any group. No dose-related changes were seen in maternal clinical findings, implantations, foetal viability, foetal size (weight and length) or visceral development. No dose-related teratogenesis was seen. Skeletal development was not affected; the few statistically significant increases in skeletal variations were not dose related and were considered to be random. FD & C Red No. 3 was neither foetotoxic nor teratogenic at the dose levels tested in drinking water.

The phototoxic effect of erythrosin B on third-stage larvae of gastrointestinal nematodes in sheep.

The phototoxic effect of erythrosin B on the infective third-stage larvae (L3) of naturally acquired mixed populations of ovine gastrointestinal nematodes was investigated. This xanthene dye was phototoxic when administered orally to parasitized lambs or applied directly to feces containing nematode ova. Phototoxicity was assessed by the lack of motility (non-swimming) exhibited by the L3 following their collection by Baermannization from cultured feces and exposure to fluorescent light for 360 min. When lambs were administered erythrosin B orally at dosages of O (control), 40, 60 and 80 mg dye kg-1 body weight daily for 10 consecutive days, the percentages of non-swimming L3 were 16%, 46%, 55% and 62%, respectively. However, erythrosin B phototoxicity did not persist after administration of the dye was discontinued and the percentage of non-swimming L3 declined to a level similar to that of the untreated controls within 2 days. The highest percentage of non-swimming L3 was observed when erythrosin B was added directly to feces containing nematode ova. A dose-response curve was evident from the successively higher percentages of non-swimming L3 with increasing concentrations of erythrosin B. Xanthene dyes have the potential to control parasites acquired by livestock on pasture by inducing a phototoxic reaction in the infective L3.

The penetration of lavage solution into the periodontal pocket during ultrasonic instrumentation.

The purpose of this study was to evaluate the penetration depth of the water coolant for medicament lavage of an ultrasonic device into the periodontal pocket. Patients having teeth previously planned for extraction, and exhibiting probing depths 3 mm or greater were used in this study. A reference notch was placed on the tooth at the level of the gingival margin and the probing attachment level (PAL) was measured from the base of the notch to the base of the pocket. The ultrasonic device, with an EWPP tip and equipped with a reservoir of erythrocin dye colored coolant, was activated and moved in a vertical direction from the gingival margin to the apical extent of the pocket. The tooth was extracted and the penetration depth (PD) of the dye-colored water spray was measured from the reference notch to the apical limit of the stained subgingival plaque. The tooth was counter stained with methylene blue to determine the coronal extent of the connective tissue attachment. Pearsons' Product Moment Correlation Coefficient for the PAL and PD was calculated. Dye-stained root surface was observed along the full extent of the probe tip's penetration path. The dispersion of the dye-colored stain was localized to the area of the ultrasonic probe with very little lateral dispersion. The ultrasonic instrument may be an effective system to mechanically remove plaque and calculus at the same time as delivering a chemotherapeutic agent. The limited dispersion of the liquid dye would indicate that chemical plaque control with this delivery system is dependent upon thorough debridement with the instrument such that all affected surfaces are instrumented.

Effects of oral erythrosine (2',4',5',7'-tetraiodofluorescein) on the pituitary-thyroid axis in rats.

Erythrosine (FD&C Red Dye No.3) is a tetraiodinated derivative of fluorescein. Rats fed a 4% erythrosine diet for 30 months beginning in utero have an increased incidence of thyroid adenomas and adenocarcinomas. These tumors may be secondary to increased stimulation of the thyroid gland by TSH. This study was undertaken to determine if dietary erythrosine disrupts the pituitary-thyroid axis thereby altering serum thyroid hormone levels. TSH levels, or the pituitary's response to TRH. Rats were fed diets containing erythrosine (0.5, 1.0, 4.0%), sodium iodide (0.16%), or fluorescein (1.6%) for 3 weeks after which TRH testing was performed in vivo. Erythrosine produced a dose-dependent increase in serum T4 levels. With the 4% erythrosine diet, serum T4 and T3 levels and the free-T4 index were significantly increased, whereas the free-T3 index were significantly increased, whereas the free-T3 index was unchanged. Rats fed the 4.0% erythrosine diet had an exaggerated TSH response to TRH; 10 min after the TRH injection, serum TSH levels were 80% greater than TSH levels of control rats. Short-term administration of erythrosine to rats decreased hepatic T3 production by decreasing its conversion of T4 to T3, indicating that erythrosine decreases hepatic 5'-deiodinase activity. These data demonstrate that dietary ingestion of 4% erythrosine disrupts the pituitary-thyroid axis as evidenced by an increased TSH response to TRH. This effect is mediated by erythrosine or an iodinated metabolite, since ingestion of its fluorescein nucleus had no effect. Erythrosine's effects were not likely mediated by iodide, because serum T4 and T3 levels were elevated and iodide administration did not increase the TSH response to TRH. These data suggest that erythrosine increases the pituitary's TSH response to TRH by altering thyrotroph cell conversion of T4 to T3. Chronic erythrosine ingestion may promote thyroid tumor formation in rats via chronic stimulation of the thyroid by TSH.

Gastrulation in the sea urchin Strongylocentrotus purpuratus is blocked by the fluorescein dye erythrosin B.

Erythrosin B, a food, drug, and cosmetic dye, arrested gastrulation in embryos of the sea urchin Strongylocentrotus purpuratus. A 30 min pulse of 5 microM erythrosin B added at 18 hr postinsemination blocked gastrulation scored at 50 hr postinsemination when control embryos had completed gastrulation. Dye addition at later times had no detectable effects on development through 50 hr postinsemination. The dye may block primary invagination via its known effects on plasma membrane permeability and fluidity.