Modeling the distribution of malachite green in zebrafish using matrix-assisted laser desorption/ionization mass spectrometry imaging.

Understanding the spatial distribution of bioactive small molecules is indispensable for elucidating their biological or pharmaceutical roles. Here, a rapid and effective analysis strategy was introduced to study the distribution of veterinary drugs in aquatic products. Malachite green (MG), one of the most widely used veterinary drugs in aquaculture, was selected as the targeted compound. Zebrafish (Danio rerio) was used as a model organism. After an exposure test, the matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) technique was applied to directly analyze the content changes of malachite green in zebrafish tissues. The reliable relationship of exposure time and content change of MG was described precisely by the extended Freundlich equation. The process of modeling was discussed in detail, and some important parameters or trend information was obtained, including the maximum content of MG in different fish tissues, time to maximum content, elimination time, equilibrium content, and so on. With a simplification of sample pretreatment, this research strategy can be used for monitoring the spatial distribution of veterinary drugs and related metabolites of laboratory-exposed fish. The obtained model can provide a perspective for rational drug use in aquaculture and precise drug residue detection in production activities.

Diagnostic utility of touch imprint cytology for intraoperative assessment of surgical margins and sentinel lymph nodes in oral squamous cell carcinoma patients using four different cytological stains.

BACKGROUND: OSCC is most commonly associated with positive surgical margins. The important cause of loco regional recurrence is histologically positive or closed margins. Clear surgical margins might favor the patient with a better prognosis and prevent repetitive surgeries. The present study was designed to the diagnostic utility of touch imprint (TI) smears using H and E, Pap, Giemsa and Feulgen stains, so that they can be used on a routine basis. MATERIALS AND METHODS: A total of 720 smears from 130 margins resected from 32 patients who underwent surgical resection of OSCC were prospectively evaluated. The slides were fixed in alcohol and randomly divided into four different batches for staining with H&E, rapid Pap, Giemsa, Feulgen stain. TI of 30 sentinel lymph node were fixed in 95% alcohol, stained by (H&E) and evaluated by two independent observers. The results were compared with gold standard histopathology. RESULTS: H&E stain showed sensitivity 44%, rapid Pap 35%, Giemsa 29% and Feulgen stain 25%. Positive predictive value-100% for all the four stains. NPV-H&E 70%, Pap 66%, Giemsa 62%, Feulgen 59%. Diagnostic test accuracy of H&E stained smears was higher 72%, compared to Pap 67%. Giemsa 65%, and Feulgen 63%. In lymph nodes, Specificity was 94.74%, PPV 90.91%, NPV 94.74%, diagnostic accuracy 93.33%. CONCLUSION: TIC is effective in identifying an inadequate or severe dysplasia margin comparable to gold standard histopathology. It might be used to intraoperatively identify metastases in sentinel lymph nodes in clinically N0 Patients.

Diagnostic application of patent blue V in sentinel lymph node biopsy for breast cancer - Is it time for a change?

Sentinel lymph node biopsy (SLNB) was introduced in the 1990s, as a minimally invasive procedure for staging the axilla with less morbidity to the traditional axillary lymph node dissection and is now standard management of the axilla in the early breast cancer. SLNB using the combined technique of blue dye and radioisotope is currently the recommended method for lymphatic mapping, and studies have shown high identification rates (IR) (>95%) and low false-negative rates (FNR) 5-10%. However, there are several reports raising awareness regarding patent blue V dye-induced peri-operative anaphylaxis. The main aim of this article is to highlight the emergence of patent blue dye as a new allergen and present evidence regarding the utility of alternative safer methods of evaluation of early breast cancer without compromising IR.

Spritzer: For diagnostic cytopathology.

BACKGROUND: Exfoliative cytology is an easy, economical, noninvasive, and feasible method for early detection and screening program of any premalignant or malignant lesion. In case of routine cytological procedure, classical Papanicolaou (PAP) stain is widely used while Romanowsky stains are sparingly used. Leishman-Giemsa (LG) cocktail, being a easier, cost effective staining technique, has not been used in exfoliative cytology. Therefore, this pilot study was carried out to compare and contrast the role of LG stain in routine cytological procedure which is very cost-effective, less time-consuming and requires less infrastructural support. AIM AND OBJECTIVES: To study the diagnostic efficiency of LG cocktail in comparison with PAP stain and Feulgen stain in mucosal cells for evaluating cellular changes of oral squamous cell carcinoma (OSCC). MATERIALS AND METHODS: Three cytological smears were prepared from 10 healthy controls and 10 patients clinically diagnosed with OSCC, and they were stained with LG cocktail stain, PAP stain, and Feulgen stain. The stained smears were evaluated for cytologic diagnosis and the staining characteristics such as nuclear and cytoplasmic details were recorded as per criteria by Sujathan et al. STATISTICAL ANALYSIS: The data were statistically evaluated with analysis of variance test using SPSS 15 software for windows. RESULTS: The results from the cases diagnosed as OSCC by PAP and LG cocktail were almost identical and superior to Feulgen stain both in diagnostic ability and in staining characteristics. CONCLUSION: The one-step LG cocktail is easy, very cost-effective, less time-consuming with less infrastructural support as compared to PAP stain; however, it warrants further evaluation for screening of oral cancer as a potential aid.

Variations in quality of carbol fuchsin stains collected from routine tuberculosis laboratories.

SETTING: In-use carbol fuchsin stains were collected from 10 different routine acid-fast bacilli smear microscopy laboratories. OBJECTIVE: To examine the variations in the composition of carbol fuchsin stains. METHOD: Carbol fuchsin concentrations were first determined spectrophotometrically by measuring absorbance at 547 nm. High-performance liquid chromatography (HPLC) separated and quantified the four basic fuchsin homologues: para-rosaniline, rosaniline, magenta II and new fuchsin, and identity was confirmed by mass spectrometry (MS). RESULTS: Absorbance measurement showed that three of 10 (30%) samples contained insufficient carbol fuchsin (<70%). Wide variations in relative proportions of fuchsin homologues were found. CONCLUSION: The relative abundance of rosaniline + new fuchsin was quite stable among the different laboratories. Spectrophotometry and HPLC/MS are necessary and sensitive tools for monitoring fuchsin quality.

Production of malachite green oxalate and leucomalachite green reference materials certified for purity.

Malachite green oxalate (MG oxalate) and leucomalachite green (LMG) have been prepared and certified as pure reference materials. The purities of MG oxalate and LMG were assessed by high-performance liquid chromatography-diode array detection (HPLC-DAD), nuclear magnetic resonance (NMR) spectroscopy, differential scanning calorimetry (DSC), Karl Fischer titration, ashing and thermogravimetric analysis (TGA). MG oxalate was purified by supercritical fluid extraction (SFE). Prior to purification, commercial MG oxalate purity was estimated to be about 90%. The main impurities present in SFE-purified MG oxalate were identified and quantified using HPLC-DAD. The main impurities were found to be monode-MG (monodemethylated MG oxalate synthesis impurity), 4-(dimethylamino)benzophenone (4-DMABP), MG-carbinol and LMG. The homogeneity of both reference materials was also determined. Issues associated with the stability of LMG and MG oxalate in solution forced an extensive study investigating different parameters i.e. solvent, acid, analyte concentration and temperature. MG oxalate (100 microg/mL) was found to be stable in acetonitrile containing 1% v/v glacial acetic acid for at least 155 days and LMG (100 microg/mL) was stable in acetonitrile for at least 133 days. The final purity value for MG oxalate was 94.3 +/- 1.4% m/m at the 95% confidence interval (or 67% m/m if MG cation is reported). For LMG, the certified purity was found to be 98.8 +/- 0.8% m/m at the 95% confidence interval.

Ziehl-Neelsen staining: theory and practice.

The information provided in the guidelines of the World Health Organization and the International Union Against Tuberculosis and Lung Disease for Ziehl-Neelsen staining is not practical on a number of points. The advice given here is meant to supplement the guidelines. It is based on experiments on and field experience of basic fuchsin stain and staining solutions.

Lessons from a proficiency testing event for acid-fast microscopy.

OBJECTIVES: To evaluate the routine performance and the technical parameters of different acid-fast staining methods: Kinyoun, Ziehl-Neelsen (ZN), auramine, and auramine-rhodamine. DESIGN AND PARTICIPANTS: The performance of 167 laboratories was analyzed using prestained and unstained slides. SETTING: Laboratories holding New York State permits. RESULTS: The results revealed that Kinyoun's cold carbol fuchsin method is inferior to both the ZN and fluorochrome (auramine and/or auramine-rhodamine) methods. Even though 91% of the participants used commercial staining kits, the study identified unexpected errors concerning the concentration of carbol fuchsin, time for staining and counterstaining, and the concentration of acid alcohol for decolorization, which may significantly influence the sensitivity. Besides these findings, the present study showed that the examination of < 300 view fields may also decrease the sensitivity of acid-fast microscopy. In addition, we found that the sensitivity and specificity of the ZN and fluorochrome methods are comparable if the procedural standards are followed. CONCLUSIONS: The strict and ongoing quality control of the "simple to perform" acid-fast microscopy and the immediate review of commercially available staining kits are necessary. Because of the rapidity of the fluorochrome method, laboratories with large specimen numbers should use this technique. In all other cases, the ZN method should be used. Moreover, all clinicians should be aware of the method of acid-fast microscopy used and the proficiency of the laboratory in performing the assay.

Chemical composition of Schiff's reagent crystals.

Crystals were prepared by adding 0.04 M sulfuric acid to a Schiff's reagent made with 2.5 g pararosaniline (PR) chloride dissolved in a saturated SO2 solution. Elemental analysis of the crystals gave the composition C19H21N3S2O7.4H2O which corresponds to the sulfate of pararosanilinesulfonic acid (PRSA) tetrahydrate. The moisture content was ca. 5%. A reagent reconstituted by dissolving 0.2 grams of crystals in HCl 0.1 N contains ca. 3.5 x 10(-3) M or 0.11% PR. A solution prepared with 2.5 g PR in 100 ml O.1 N HCl plus 0.04 M M K2S2O5 gave only a few crystals after 0.04 M sulfuric acid was added. The PR content, determined colorimetrically, was 0.25% compared with 1.35% in saturated SO2. The per cent dye loss during charcoal purification was also higher. The low concentration of PR, caused both by the lower solubility and by the larger loss during charcoal purification explains the poor yield of crystals of a reagent prepared in HCl/K2S2O5, compared to a reagent prepared in saturated SO2. After crystallization is complete, the crystals are in equilibrium with a concentration of 0.2% of PR in the supernatant: when the initial concentration is close to this value crystallization is negligible or completely fails.

Effects of chemistry, manufacturing and concentration of the dye basic fuchsin regarding its use in quantitative cytophotometry.

Four separately manufactured preparations of basic fuchsin were compared to determine the effects of concentration, chemistry, and the manufacturing process for their quantitative value in the nuclear Feulgen reaction. In order to make the necessary comparisons, the two wavelength method of quantitative cytophotometry was employed to analyse each stain application regarding DNA measurements. Chicken erythrocytes, and myxamoebae and plasmodia of Didymium iridis were employed as experimental tissues. Results indicated that all four preparations of the stains yielded acceptable and valid quantitative data in relative DNA values. Differing manufacturers and dye concentrations had no appreciable effect on relative quantitative measurements. However, the maximum staining intensity was affected by differences both in the chemical structure of the individual stains and by the products from various manufacturers. The maximum dye intensity and accurate quantitative absolute values for DNA measurement were best obtained by the use of basic fuchsin having the same colour index (Cl) 42510 as that manufactured by Fisher Scientific Incorporated.