Cytocentrifuged biopsy fixative preparation: A simple cost-effective technique facilitating microscopic diagnosis of lumen-dwelling intestinal parasites.

OBJECTIVE: Direct microscopic visualization is the most specific method for detecting intestinal parasites and is commonly achieved by stool examination or mucosal biopsy. However, postfixation, the intestinal biopsy fragment is often curled, and the entire surface of the biopsied mucosa is seldom viewed microscopically. Tissue processing further distorts morphology of the organisms and causes diagnostic difficulties. Examining multiple sections for parasite detection is time-consuming and often requires aid of special stains and/or immunohistochemistry. To overcome these disadvantages, we hypothesized that the fixative in which biopsies are transferred may provide a valid representation of the biopsied mucosal surface and therefore aid in the identification of mucosal surface parasites. MATERIALS AND METHODS: Formalin in which biopsies were transferred was retained, stored at 4°C and processed with a cytocentrifuge. Totally, 120 consequent duodenal biopsy fixatives were processed in this way and the cytocentrifuged smears visualized after May-Grunwald-Giemsa staining. Findings of these smears were correlated with their corresponding formalin fixed paraffin embedded tissue sections. RESULTS: Cytocentrifuged formalin preparations were found to be representative of the mucosal surface contents. Giardia trophozoites were visualized in 10/120 preparations with distinct morphological characteristics which were seldom appreciable in tissue sections, eliminating the need for special stains. Furthermore, two of the corresponding histology sections did not demonstrate the parasites despite step sections, while in one case few parasites could be identified in the step sections. CONCLUSIONS: Cytocentrifuged fixative preparation is a simple and cost-effective technique which can be routinely employed for intestinal parasite characterization.

An image-based algorithm for precise and accurate high throughput assessment of drug activity against the human parasite Trypanosoma cruzi.

We present a customized high content (image-based) and high throughput screening algorithm for the quantification of Trypanosoma cruzi infection in host cells. Based solely on DNA staining and single-channel images, the algorithm precisely segments and identifies the nuclei and cytoplasm of mammalian host cells as well as the intracellular parasites infecting the cells. The algorithm outputs statistical parameters including the total number of cells, number of infected cells and the total number of parasites per image, the average number of parasites per infected cell, and the infection ratio (defined as the number of infected cells divided by the total number of cells). Accurate and precise estimation of these parameters allow for both quantification of compound activity against parasites, as well as the compound cytotoxicity, thus eliminating the need for an additional toxicity-assay, hereby reducing screening costs significantly. We validate the performance of the algorithm using two known drugs against T.cruzi: Benznidazole and Nifurtimox. Also, we have checked the performance of the cell detection with manual inspection of the images. Finally, from the titration of the two compounds, we confirm that the algorithm provides the expected half maximal effective concentration (EC50) of the anti-T. cruzi activity.

Portable and cost-effective pixel super-resolution on-chip microscope for telemedicine applications.

We report a field-portable lensless on-chip microscope with a lateral resolution of <1 µm and a large field-of-view of ~24 mm(2). This microscope is based on digital in-line holography and a pixel super-resolution algorithm to process multiple lensfree holograms and obtain a single high-resolution hologram. In its compact and cost-effective design, we utilize 23 light emitting diodes butt-coupled to 23 multi-mode optical fibers, and a simple optical filter, with no moving parts. Weighing only ~95 grams, we demonstrate the performance of this field-portable microscope by imaging various objects including human malaria parasites in thin blood smears.