Ultrafast Toluidine Blue Staining for Rapid On-Site Evaluation of Cytological Smears

Rapid on-site evaluation (ROSE) is one of cytopathology's "unique selling propositions." The quality, speed, and ease of handling of the staining used is a critical factor for the efficacy of the ROSE procedure. Here, we describe a modification of rapid toluidine blue staining that can be performed within 25 s, provides excellent nuclear morphology, and is compatible with subsequent Papanicolaou staining of the slides. Furthermore, exposure to hazardous chemicals is minimized, as no organic solvents other than the alcohol-based fixative and glycerin for temporary mounting and coverslipping are required. We have used this protocol successfully in our ROSE practice and have not observed any discrepancies between toluidine blue- and permanent Papanicolaou-stained slides.

Antimicrobial photodynamic activity of toluidine blue-carbon nanotube conjugate against Pseudomonas aeruginosa and Staphylococcus aureus - Understanding the mechanism of action

BACKGROUND

The emergence of drug-resistant bacterial strains has raised the need to develop alternative treatment modalities to combat infectious diseases. Antimicrobial photodynamic therapy (aPDT) is an alternative to conventional treatment modalities. aPDT integrates a photosensitizer, which, after exposure to light of an appropriate wavelength, leads to the generation of cytotoxic reactive oxygen species (ROS).

METHODS

The aim of the present study was to synthesize a toluidine blue/multiwalled carbon nanotube conjugate (TBCNT) for enhanced photoinactivation of Pseudomonas aeruginosa and Staphylococcus aureus. Synthesized TBCNT conjugate was characterized and its antibacterial and antibiofilm activity was determined.

RESULTS

During TBCNT synthesis, dye loading, and entrapment efficiency of the CNT were 12.04 ± 0.55% and 48.99 ± 2.33%, respectively. The photo-destruction of planktonic cells of the test bacteria was performed by exposure to a 125 mW red laser with a wavelength of 670 nm (radiant exposure of 58.49 J/cm²) for 3 min. Photoinactivation using TBCNT resulted in a 4.91- and 5.47-log10 reduction in P. aeruginosa and S. aureus, respectively. The mechanism of this aPDT was studied by measuring intracellular ROS generation, protein leakage, and lipid peroxidation in the test bacteria after light irradiation. The antibiofilm activity of TBCNT after light exposure was 69.94% and 75.54% for P. aeruginosa and S. aureus, respectively. Photoinactivation of test bacteria treated with TBCNT reduced cell viability and exopolysaccharide production. Confocal laser-scanning microscopy revealed a significant biofilm inhibition efficacy of the TBCNT conjugate.

CONCLUSION

Therefore, TBCNT conjugates may be used for the eradication of P. aeruginosa and S. aureus biofilms.

Chitosan Inhibits the Rehabilitation of Damaged Microbes Induced by Photodynamic Inactivation

Previously, we showed that chitosan could augment the biocidal efficacy mediated by photodynamic treatment against Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans. In this study, we showed that the antimicrobial action of chitosan in augmenting photodynamic inactivation (PDI) is related to the increase in cell surface destruction. The microbial cell surfaces exhibit severe irregular shapes after PDI in the presence of chitosan as demonstrated by transmitted electron microscopy. Furthermore, increases in the concentration or incubation time of chitosan significantly reduced the amounts of photosensitizer toluidine blue O required, indicating that chitosan could be an augmenting agent used in conjunction with PDI against S. aureus, P. aeruginosa, and C. albicans. A prolonged lag phase was found in microbial cells that survived to PDI, in which chitosan acted to completely eradicate the cells. Once the exponential log stage and cell rebuild began, their cellular functions from PDI-induced damage returned and the increased cytotoxic effect of chitosan disappeared. Together, our results suggest that chitosan can prevent the rehabilitation of PDI-surviving microbial cells, leading to increased biocidal efficacy.

The efficacy of photodynamic and photothermal therapy on biofilm formation of Streptococcus mutans: An in vitro study

BACKGROUND

The alternative antibacterial treatments of photodynamic therapy (PDT) and photothermal therapy (PTT) significantly affect microbiota inactivation. The aim of the present research was the assessment of the antimicrobial and anti-biofilm effects of PDT with toluidine blue O (TBO) and PTT with indocyanine green (ICG) on Streptococcus mutans as a cariogenic bacterium.

MATERIALS AND METHODS

The S. mutans ATCC 35668 strain was treated with final concentrations of 0.1mg/mL TBO and 1mg/mL ICG with energy densities of 17.18 and 15.62J/cm², respectively. Cell viability was evaluated after culturing and anti-biofilm potential was analyzed using crystal violet assay and scanning electron microscopy.

RESULTS

The number of S. mutans colony forming unit (CFU)/mL was significantly lower in the groups submitted to PDT (12.5-100μg/mL TBO) and PTT (62.5-1000μg/mL) compared to the control (untreated group). 0.1mg/mL TBO-PDT and 1mg/mL ICG-PTT showed stronger inhibitory effects on biofilm formation in S. mutans than other concentration levels, with a reduction of 63.87% and 67.3%, respectively.

CONCLUSION

Photo-elimination by high concentrations of TBO-PDT and ICG-PTT exhibited significantly stronger inhibitory effects on biofilm formation and cell viability in S. mutans.

Assessment of cervical passage of vital dyes in pregnant, nonpregnant, and mated rats and mice

Risk assessment for indirect exposure to small molecule pharmaceuticals in semen to the conceptus has traditionally been handled by calculations based on assumptions that any embryo-fetal exposure would be secondary to maternal absorption and redistribution. This study was designed to assess the potential for transcervical passage of drugs from semen. Reproductive tracts of rodents were examined following vaginal dosing with vital dyes during the estrous cycle, mating, and pregnancy. Toluidine Blue was not observed beyond the cervix after vaginal administration in pregnant rats; additionally, it did not pass the cervix in rats during any phase of estrous. In order to address the effects of semen, rats were dosed at receptivity and mated. Vital dyes were not visually evident in the uterus despite vaginal and sperm plug staining. This study provides evidence that direct transcervical passage is not a substantial route of direct embryo-fetal exposure for small molecule drugs in semen.

Vulvoscopy: review of a diagnostic approach requiring clarification

The objective of this review is to clarify what, if any, role there is for colorimetric (acetic acid and toluidine blue) testing and colposcopic examination of the vulva by reviewing the literature regarding use of the colposcope and colorimetric tests in the diagnosis of vulvar disorders. The lack of established usefulness of colposcopic observation for common dermatologic entities affecting the vulva markedly reduces the need for the colposcopist's skills in dealing with disorders of the vulva. Conversely, vulvar, as opposed to cervical, disorders place more emphasis on a gynecologist's knowledge and experience with dermatologic disease. The use of the colposcope and acetic acid, toluidine blue or both adds little or nothing to "naked-eye" examination of the vulva. The term vulvoscopy is appropriate and useful because it is easy to comprehend. However, vulvoscopy should be defined as a composite diagnostic act composed of careful naked-eye and low-power magnified examination carried out by those with interdisciplinary skills, such as vulvologists.

Potential of photodynamic therapy in treatment of fungal infections of the mouth. Design and characterisation of a mucoadhesive patch containing toluidine blue O

Mucocutaneous oropharyngeal candidiasis is predominately caused by Candida albicans. The overall incidence of oral candidiasis in young adults has increased dramatically with the spread of HIV/AIDS. Conventional treatments have been shown to have a fungistatic rather than a fungicidal effect, resulting in an inadequate treatment outcome for patients. In addition, increasing resistance of C. albicans to antifungal agents has made effective treatment more difficult. Accordingly, interest has arisen in development of new prophylaxis/treatment regimens. One such alternative treatment is photodynamic antimicrobial chemotherapy (PACT), in which a combination of a photosensitising drug and visible light cause selective destruction of microbial cells. Due to the highly coloured nature of photosensitisers and the potential for staining of teeth, lips and buccal mucosa, administration of photosensitisers to humans as a liquid mouthwash is undesirable. Targeted delivery of the photosensitiser directly to the site of infection should be the aim. The current study, therefore, reports on a mucoadhesive patch containing toluidine blue O (TBO), as a potential delivery system for use in PACT of oropharyngeal candidiasis. Patches prepared from aqueous blends of poly(methyl vinyl ether/maleic anhydride) and tripropyleneglycol methyl ether possessed suitable properties for use as mucoadhesive drug delivery systems and were capable of resisting dissolution when immersed in artificial saliva. When releasing directly into an aqueous sink, patches containing 50 and 100mg TBO cm(-2) both generated receiver compartment concentrations exceeding the concentration (2.0-5.0 mg ml(-1)) required to produce high levels of kill (>90%) of both planktonic and biofilm-grown C. albicans upon illumination. However, the concentrations of TBO in the receiver compartments separated from patches by membranes intended to mimic biofilm structures were an order of magnitude below those inducing high levels of kill, even after 6h release. Therefore, short application times of TBO-containing mucoadhesive patches should allow treatment of recently-acquired oropharyngeal candidiasis, caused solely by planktonic cells. Longer patch application times may be required for persistent disease where biofilms are implicated.

Ex-vivo study of high-magnification chromoendoscopy in the gastrointestinal tract to determine the optimal staining conditions for endocytoscopy

BACKGROUND AND STUDY AIMS

Endocytoscopy allows the observation of living cells in the gastrointestinal tract. Consistently clear views are essential for clinical application of the technique, but these are not always obtained. The aim of this study was to determine an appropriate staining regimen for endocytoscopy.

MATERIALS AND METHODS

This was an ex-vivo animal study in which we stained freshly resected porcine esophagus, stomach, and colon with different concentrations of three dyes (1%, 0.5%, and 0.25% crystal violet; 5%, 2.5%, and 1% methylene blue; and 1%, 0.5%, and 0.25% toluidine blue) and assessed them after different exposure times (10 seconds, 30 seconds, 60 seconds, and 90 seconds). The images obtained were evaluated according to the staining status of the cytoplasm and the nucleus, and the contrast between the cytoplasm and the nuclei, and the optimal staining conditions for each organ were determined. Additionally, freshly resected human esophagus, stomach, and colon tissues were tested under the dye/exposure conditions that were found to be the most appropriate in the animal study.

RESULTS

After intensive mucus removal, high-quality images were obtained using methylene blue and toluidine blue. The optimum conditions for endocytoscopic observation were obtained after staining with 1% methylene blue in the esophagus and with 0.25% toluidine blue in the stomach and the colon, after 60 seconds of exposure to the dye. This was confirmed in the human specimens.

CONCLUSIONS

This study provides important information on appropriate staining conditions for endocytoscopy. Further ex-vivo and in-vivo studies are necessary before this technique comes into standard use, however.

Pharmacokinetics and toxicity of tolonium chloride in sheep

The pharmacokinetic disposition, urinary excretion and toxicity of tolonium chloride were determined after i.v. administration to sheep. Pretreatment with sodium nitrite significantly decreased the volume of the central compartment, apparent volume of distribution, area under the concentration-time curve, and total body clearance of tolonium chloride. Urinary excretion of tolonium chloride and its metabolite, leucotolonium chloride, together accounted for less than 15% of the administered dose in sheep receiving sodium nitrite and less than 10% of the administered dose in control sheep. The LD50 of tolonium chloride was 10 mg/kg with a 95% confidence interval of 7.35-13.60 mg/kg. Comparison with previously published data describing the pharmacokinetics and toxicity of a related compound, methylene blue, indicated that tolonium chloride has a higher volume of distribution and a narrower therapeutic index.

Sensitisation of Candida albicans to killing by low-power laser light

The purpose of this study was to determine whether Candida albicans, and other Candida spp. responsible for HIV-associated candidosis, could be sensitised to killing by low-power laser light. Suspensions of C. albicans were treated with a number of potential photosensitisers, exposed to laser light from a Helium/Neon (HeNe) or Gallium aluminium arsenide (GaAs) laser for 120 s and survivors enumerated. Toluidine blue O (TBO), thionin and crystal violet were able to sensitise the yeast to killing by light from the HeNe laser (energy dose = 876 mJ at a density of 66.36 J/cm2), the kills achieved being 6.8 x 10(6) cfu/ml, 3.1 x 10(6) cfu/ml and 1.3 x 10(6) cfu/ml respectively. TBO was also able to sensitise several other Candida spp. to killing by HeNe laser light. Dihaematoporphyrin ester was not an effective photosensitiser under the conditions employed. Methylene blue, but not aluminium disulphonated phthalocyanine, was able to sensitise C. albicans to killing by light from the GaAs laser (energy dose 1.32 J at a density of 2.04 J/cm2). The viability of the yeast was not affected by exposure to laser light in the absence of the photosensitisers. As killing of dye-sensitised C. albicans, and other Candida spp., could be achieved by exposure to low-power laser light for short periods of time, this approach merits further investigation as a potential therapeutic modality for HIV-associated candidosis.

Tolonium (toluidine blue) rinse--a screening method for recognition of squamous carcinoma. Continuing study of oral cancer IV

Tolonium chloride (toluidine blue) application is useful for identifying malignant changes in squamous mucosa. However, early asymptomatic mucosal changes may remain undetected by tolonium application. A study was carried out to determine the feasibility of using a tolonium mouth rinse as a routine procedure after thorough clinical examination, to discover undetected cancers. A proved, effective tolonium application method was compared with a rinse sequence. One hundred five asymptomatic oral lesions (51 carcinomas and 54 nonmalignant lesions) that persisted for ten to 14 days were evaluated with application and rinse modalities and biopsies. There were 2% false-negatives (1/51) with the application as opposed to 5.9% (3/51) with the rinse and 9.3% false-positives (5/54) with the application as compared to 7.4% (4/54) with the rinse. Four inapparent, second primary cancers, unobserved for application, were delineated by the rinse (three oral, one pharyngeal). Tolonium blue rinse may be used to detect unobserved, asymptomatic oral mucosal cancers after clinical examination. After a positive rinse stain, a subsequent positive application stain ten to 14 days later mandates a biopsy of the lesion.

Dose dependent uptake of 125I-toluidine blue of 75Se-selenomethionine in the parathyroids of rabbits

Different dosages of 125I-toluidine blue and 75Se-selenomethionine were injected intravenously into rabbits, and the concentration of radioactivity was measured in the parathyroids and surrounding tissues. The response of i.v. injected glucagon was also determined. It was found that 0.16 mg 125I-toluidine blue gave a concentration ratio of parathyroid/thyroid and parathyroid/muscle which was significantly higher than both lower and higher doses at 1 minute after i.v. injection of the labelled dye. Glucagon had little or no effect on the uptake of 125I-toluidine blue and 75Se-selenomethionine.

Use of tolonium chloride in the diagnosis of malignant gastric ulcers

Peroral staining with tolonium chloride (toluidine blue) was performed in 45 patients with suspected gastric ulcer disease. During endoscopy, 19 of 21 malignant ulcers and one of 15 benign ulcers were stained. Following surgery, 18 of 21 malignant ulcers found in the surgical specimens were stained. Eleven patients with benign ulcers underwent surgery and none of these ulcers were found to be stained in the surgical specimens. Normal gastric mucosa and areas of gastritis appeared unchanged. The data suggest that tolonium chloride staining prior to endoscopy or surgery seems to be helful in differentiating between minute benign and malignant gastric ulcers.

Peroral staining method with toluidine blue as an aid in the diagnosis of malignant gastric lesions

Peroral, intragastric staining method with toluidine blue was performed in 42 patients with suspected neoplastic lesions of the stomach. Fifteen out of 18 malignant lesions and one out of 13 benign lesions were stained. Normal mucosa, areas of gastritis and most of the benign lesions appeared unchanged. According to our results, the use of toluidine blue staining method prior to endoscopy might be of help in demonstrating minute malignant lesions of gastric mucosa and in the differential diagnosis between benign and malignant ulcers of the stomach.

The use of toluidine blue in locating abnormal parathyroid tissue at operation

The use of toluidine blue solution infused intraoperatively in order to stain selectively abnormal parathyroid tissue was assessed in nine patients with the clinical diagnosis of hyperparathyroidism. There was one case of hyperplasia, one of carcinoma and seven of solitary adenoma. In all cases abnormal parathyroid tissue could be distinguished from adjacent neck tissue. Staining was of particular benefit in the cases of parathyroid tissue in ectopic sites. Dye infusion was tolerated well and all patients had an uncomplicated postoperative course. No cardiotoxicity was apparent. In five patients who had undergone radioimmunoassay studies of parathyroid hormone the use of toluidine blue was also found to be of assistance.

Structural features of histamine release in rat peritoneal mast cells. A study with toluidine blue

Cellular events correlated to the histamine release process were studied in rat peritoneal mast cells applying the dye toluidine blue as histamine-discharging agent. The effects of toluidine blue were studied both in the presence and absence of calcium. Histamine release was clearly dose-dependent within the range 2X10^––⁵ m toluidine blue to 4X10^––4 m. Whereas spontaneous histamine release values were in the order of a few percent, maximum release in the presence of calcium amounted to 65–80%. Histamine release was accompanied by characteristic morphologic changes in the cells: granule fine structure was markedly altered, perigranular vacuoles were formed and, through repeated fusions of the vacuole-delimiting membranes, large caveolae containing granule matrices arose. In fortuitous sections, these cavities were seen to communicate with the extracellular space through pores, often of substantial size. Granule extrusion from the cellular domain to the surrounding medium, although it did occur to a certain extent, was not a prominent feature of the histamine release process. The dose-response curve for histamine release was lowered by roughly one half in the absence of calcium. This was reflected in mast cell morphology by a decreased tendency towards granule alteration and vacuole formation. The present observations are viewed in the light of various suggested models for the mode of histamine release from mast cells.