Visualization of fungi in histological sections

Deparaffinized kidney sections from mice infected with Candida albicans and lung sections from mice infected with Blastomyces dermatitides were stained with the stilbene derivative, Uvitex 2B (1%), and counterstained with haemalum and eosin. Fungi selectively stained with Uvitex 2B are visualized by blue fluorescence under incident illumination with ultraviolet light. Simultaneous or consecutive illumination with transmitted light permits the assignment of fluorescent fungi to haemalum-eosin-stained structures in the section. The most practical means of achieving a high optical contrast with Uvitex 2B in sections and good haemalum-eosin staining is to use the established haemalum-eosin technique, but with a solution containing both 1% eosin and 1% Uvitex 2B in place of eosin alone. Since Uvitex 2B stains all fungi investigated so far, it affords a simple, sensitive and inexpensive method of selectively detecting opportunistic fungal infections in conventional histopathology.     

Immunocytochemical identification of amyloid in formalin-fixed paraffin sections

Summary Formalin-fixed paraffin sections of livers, spleens and kidneys from patients with primary, secondary and familial amyloidosis as well as from a casein-induced murine amyloid model were analysed by an immunocy-tochemical (unlabeled antibody enzyme) method utilizing antisera to amyloid-related proteins. All amyloid deposits of all amyloid types showed positive reactions with anti-AP of the respective species. Positive reaction of anti-human AA to human secondary amyloid deposits and of anti-mouse AA to the deposits of casein-induced murine amyloid was also observed, but there was no species cross reactivity. No significant deposition of the reaction products was produced by anti-immunoglobulin light chains on deposits of any amyloid type, or by anti-AA in the tissues from primary or familial amyloidosis. The results indicate that amyloid proteins AA and AP can survive as antigens through routine histologic preparation, that anti-AP can be a universal marker for deposits of any amyloid type within the same species, and that AA-type amyloid can be identified by this method while there may as yet be no feasible universal marker for the AL-type at present.Presented in part at the 64th Annual Meeting of the Federation of American Societies for Experimental Biology, Anaheim, California, April, 1980     

TdTomato and EGFP identification in histological sections: insight and alternatives

Abstract

Tandem dimer Tomato (tdTomato) provides a useful alternative to enhanced green fluorescent protein (eGFP) for performing simultaneous detection of fluorescent protein in histological sections together with fluorescence immunohistochemistry (IHC). eGFP has many properties that make it useful for cell labeling; however, during simultaneous fluorescence IHC, the usefulness of eGFP may be limited. This limitation results from a fixation step required to identify eGFP in histological tissue sections that can mask antibody epitopes and adversely affect staining intensity. An alternative fluorescent protein, tdTomato, may assist concurrent detection of fluorescent protein within tissue sections and fluorescence IHC, because detection of tdTomato does not require tissue fixation. Tissue sections were obtained from various organs of mice ubiquitously expressing eGFP or tdTomato that were either unfixed or fixed with 4% paraformaldehyde. These tissues later were combined with fluorescence IHC. Both eGFP and tdTomato displayed robust signals in fixed frozen sections. Only tdTomato fluorescence, however, was detected in unfixed frozen sections. Simultaneous detection of fluorescence IHC and fluorescent protein in histological sections was observed only in unfixed frozen tdTomato tissue. For this reason, tdTomato is a useful substitute for eGFP for cell labeling when simultaneous fluorescence IHC is required.     

Evaporation process in histological tissue sections for neutron autoradiography

The analysis of the distribution and density of nuclear tracks forming an autoradiography in a nuclear track detector (NTD) allows the determination of ¹⁰B atoms concentration and location in tissue samples from Boron Neutron Capture Therapy (BNCT) protocols. This knowledge is of great importance for BNCT dosimetry and treatment planning. Tissue sections studied with this technique are obtained by cryosectioning frozen tissue specimens. After the slicing procedure, the tissue section is put on the NTD and the sample starts drying. The thickness varies from its original value allowing more particles to reach the detector and, as the mass of the sample decreases, the boron concentration in the sample increases. So in order to determine the concentration present in the hydrated tissue, the application of corrective coefficients is required. Evaporation mechanisms as well as various factors that could affect the process of mass variation are outlined in this work. Mass evolution for tissue samples coming from BDIX rats was registered with a semimicro analytical scale and measurements were analyzed with software developed to that end. Ambient conditions were simultaneously recorded, obtaining reproducible evaporation curves. Mathematical models found in the literature were applied for the first time to this type of samples and the best fit of the experimental data was determined. The correlation coefficients and the variability of the parameters were evaluated, pointing to Page’s model as the one that best represented the evaporation curves. These studies will contribute to a more precise assessment of boron concentration in tissue samples by the Neutron Autoradiography technique.     

Involvement of endogenous digitalis-like substance in genesis of deoxycorticosterone-salt hypertension

In an attempt to evaluate the role of endogenous digitalis-like substance in the genesis of deoxycorticosterone (DOCA) -salt hypertension, the effects of intravenous anti-digoxin antibody on the blood pressure response were observed in male Wistar rats that underwent heminephrectomy followed by treatment with DOCA and saline. Administration of anti-digoxin antibody caused a marked decrease in the blood pressure which continued for about an hour. Such a change in the blood pressure was not observed in pertinent control animals. Thus, it seems that endogenous digitalis-like substance plays an important role in the genesis of DOCA-salt hypertension.