PrestoBlue® and AlamarBlue® are equally useful as agents to determine the viability of Acanthamoeba trophozoites.

Acanthamoeba is an opportunistic pathogen which is the causal agent of several human infections such as Granulomatous Amoebic Encephalitis, Acanthamoeba keratitis and other disseminated infections. Furthermore, current therapeutic measures against Acanthamoeba infections are arduous, and show limited efficacy against the cyst stage of Acanthamoeba. There is a pressing need to search and evaluate new therapeutic agents against these protozoa. Our approach for evaluating possible new drugs is an initial in vitro screening assay based on general metabolic activity of the cells. In this study we compare two agents, AlamarBlue® and PrestoBlue® for this initial screen. Both reagents can be used to indicate metabolism by changes in their absorbance or fluorescence. The assay is carried out in a 96-well plate format and fluorescence can be measured after an inoculation period of as little as 10 min, but more typically 96 h. This to the best of our knowledge this is the first time that both compounds are directly compared using absorbance and fluorescence measurement. We conclude that for the specific case of Acanthamoeba both agents AlamarBlue® and PrestoBlue® are equally useful to determine cell viability.

Rhodamine conjugates:specific and nonspecific binding properties in immunohistochemistry.

Anionic-exchange fractions of IgG labeled with FITC, MRITC, RB200SC, or RBITC were tested on different substrates, and the resultant fluorescence was evaluated with the Ploem optical system. Conjugations with MRITC or RB200SC were found to afford the following advantages over FITC: immunofluorescence sensitivity was elevated six to seven times on a molar basis; high sensitivity could be combined with a wide specificity interval; there was negligible fading of emitted light; there was negligible tissue autofluorescence at the excitation wavelength (546 nm); because of the two latter points, repeated observations could be made on tissue sections stored for several years; and eosinophilic leukocytes that are prone to yield nonspecific staining could easily by identified by switching to ultraviolet-blue light excitation.

Fine needle aspiration of parathyroid lesions.

OBJECTIVE: To assess the cytologic features of parathyroid lesions and to determine if it is possible to differentiate between parathyroid hyperplasia (PH) and parathyroid adenoma (PA) based on fine needle aspiration (FNA). STUDY DESIGN: FNAs of 14 parathyroid lesions were performed during intraoperative consultation. Alcohol-fixed, Papanicolaou-stained smears and air-dried Diff-Quik-stained smears were prepared in each case. Cytologic features were evaluated. RESULTS: All cases, PA and PH, showed numerous bare nuclei in the background. Ninety percent of PA contained microfollicular groups in addition to sheets and syncytia, while PH was arranged primarily in sheets and syncytia without microfollicles. Nuclear pleomorphism was seen in 33% of PA and absent from PH. CONCLUSION: Careful evaluation of cytologic features might help to differentiate between PA and PH on FNA.

Identification of the source of reagent variability in the xanthydrol/urea method.

Contamination of food and food packaging material by rodent urine is evidence of insanitary conditions. Urea from rodent urine is used as a chemical indicator of contamination. The limit of detection of the xanthydrol/urea AOAC Method 959.14 by formation of dixanthylurea crystals is 4 micrograms urea isolated from urine on packaging material. Six different lots of xanthydrol from 5 different manufacturers were compared. Differences in urea detection sensitivity of the xanthydrol of up to 1000-fold were observed. Melting points showed further evidence of variability and impurities in xanthydrol lots. A liquid chromatographic method was developed to separate and identify the impurities. Confirmation of analytes was performed by gas chromatography/mass spectrometry.

Use of telecytology for the immediate assessment of CT guided and endoscopic FNA cytology: diagnostic accuracy, advantages, and pitfalls.

Telecytology (TC) can assist cytopathologists in efficiently providing immediate evaluation for fine needle aspirations (FNAs) performed at remote locations. Our aim was to evaluate the accuracy and feasibility of TC for immediate assessments of FNAs. Phase I: Diff-Quik and Pap stained smears from two retrospective sets of 20 pilot cases each (n = 40) were included for TC assessments. For the first set, diagnoses were rendered by four pathologists and for the second set, in addition, four cytotechnologists also participated. Diagnostic concordance with the final diagnosis was assessed. Phase IIA: These were followed by real time assessments (RTA) of 56 TC FNAs and diagnostic concordance was compared to that of 100 conventional in-person immediate assessments (Phase IIB). Phase I: 79/80 (98.8%) diagnoses (20 cases × 4 pathologists) from the first set were accurate. On the second set, 160 diagnoses were rendered on Pap stained slides and 160 on Diff-Quik stained slides. The accuracy rate was 95% (76/80) for malignant diagnoses and 96.2% (77/80) for benign diagnoses on Pap stain. Diff-Quik stains were more difficult to interpret than Pap stains and accuracy rates for them were lower. Endoscopic bronchial ultrasound guided (EBUS) FNAs of paratracheal nodes were more difficult to interpret. Phase IIA and B: 95% (53/56) RTAs by TC were concordant with the final diagnoses compared with 97% (97/100) for in-person assessments. TC is a useful aid and yields concordance rates comparable to in-person assessments. Individual practices should perform pilot studies to understand the pitfalls and limitations before employing telecytology.