Biomedical subjects

V H Tomasi

Publications and source records attributed to V H Tomasi.

3 recordsLinked to original sources

PubMed2003

A new technique for staining mast cells using ferroin.

We describe here a new method for specific staining of mast cells using ferroin. Different hamster tissues were fixed in 4% formalin and processed for paraffin embedding. Sections were stained with hematoxylin followed by ferroin acidified with 2.5 N sulfuric acid to pH 4.0. Mast cells stained an intense orange color that contrasted markedly with bluish violet nuclei. High contrast was also observed when ferroin colored sections were counterstained with light green instead of hematoxylin. To evaluate the specificity of the stain, hamster cheek pouch sections were stained with toluidine blue, alcian blue-safranin O, and ferroin. Quantitative evaluation of mast cells stained with the three techniques showed no statistical difference. The simplicity and selectivity of this method is sufficient for image analysis of mast cells.

Alcian Blue↗

PubMed2001

Modified silver staining of nucleolar organizer regions to improve the accuracy of image analysis.

Silver staining of nucleolar organizer regions (NORs) and their subsequent quantification by image analysis are used increasingly in human pathological specimens and experimental models. Because certain conditions determined by the type of tissue and/or its fixation render AgNOR segmentation for image analysis difficult due to insufficient contrast or nonspecific silver precipitation, we propose three improvements to the original technique to overcome these difficulties. Pretreatment with 7% nitric acid produced very distinct dark brown images of AgNORs on a yellow background. The gradient of background colors allowed easy discrimination of nucleolar, nuclear and cytoplasmic structures. Seven morphometric parameters related to number, size and shape of AgNORs were evaluated quantitatively by image analysis on sections pretreated with nitric acid and on adjacent sections treated with citrate buffer in a wet autoclave according to the most widely accepted method for image analysis of AgNOR. Both methods yielded similar results. A second improvement was achieved by coating the slides with 7% celloidin solution in ethyl alcohol-ether prior to AgNOR staining and acid pretreatment. This coating prevented nonspecific silver deposition on argyrophilic bacteria and other tissue debris in human vaginal smears that could make visualizing AgNOR sites difficult. Finally, placing sections face down on the staining solution prevents the formation of nonspecific silver precipitates. These procedures can be applied together or separately according to the requirements of the material to be evaluated.

Adenocarcinoma↗

PubMed1997

Softening of plant specimens (Equisetaceae) to improve the preparation of paraffin sections.

A method is presented for softening the hard tissues of stem and strobile of Equisetum giganteum allowing the preparation of representative histological slides suitable for teaching and research. Segments of aerial portions of the Equisetum giganteum shoot system were fixed with formaldehyde:ethanol:acetic acid (5:10:5) for 24 hr at room temperature, washed in distilled water and immersed in a mixture of 5% hydrofluoric acid and 0.5% sulfuric acid for 1 hr at room temperature. Hydrofluoric acid has a higher affinity for silica components, and the sulfuric acid acts as a catalyst favoring the separation of calcium silcates. This simple, inexpensive and rapid method allows paraffin sections to be prepared while preserving the topographic microanatomy by decreasing technical artifacts produced by conventional softeners, and preserving PAS-positive polysaccharides.

Paraffin Embedding↗