Cadaver preservative properties of a solution composed of honey, ethyl alcohol, liquid paraffin, distilled water and citric acid: Experiments on rabbit cadavers.

The objective of this study is to assess the efficacy of a solution including honey, ethyl alcohol, liquid paraffin, distilled water and citric acid (HEFS) as a preservative for rabbit cadavers, serving as a potential substitute for formaldehyde. The cadavers underwent preservation using three distinct solutions: 10% formalin, 35% alcohol and HEFS. The cadavers were subjected to a total of four sampling events, occurring at 4-month intervals, in order to collect specimens for microanatomical, histological, microbiological, mycological, colourimetric, texture and odour analysis. In terms of hardness, suitability for dissection and joint mobility metrics, the cadavers fixed with HEFS had superior qualities to those fixed with formalin. The fixation quality of HEFS for histological analyses was deemed acceptable, except kidney and intestinal tissues. In texture analysis, differences only in the elasticity parameter (p < 0.05) in the same sampling period. A total of 10 (13.9) bacteria isolates were identified among which, Metasolibacillus meyeri 3 (30%) was predominantly followed by Staphylococcus aureus 2 (20%), Bacillus siamensis, Bacillus subtilis, Pseudarthrobacter oxydans, Bacillus licheniformis, Bacillus subtilis subsp. subtilis with a proportion of 1 (10%), respectively, by both microbiological and molecular analysis. However, no anaerobic bacteria and fungi were isolated. A considerable percentage of the students had the perception that HEFS was appropriate for utilization in laboratory settings due to its absence of unpleasant odours and detrimental impact on ocular and respiratory functions. In conclusion, we consider that HEFS may serve as a viable substitute for formalin solution in the preservation of rabbit cadavers.

Sirka: An alternative to the formalin fixative.

Formalin fixation is the most essential step of routine histopathology practice. During the last few years, various fixatives have been developed for use in histopathology practice as an alternative to formalin, to overcome its side effects on health. Here we have demonstrated an interesting and novel idea of using sirka or sugar cane vinegar as an alternative to the formalin with the adequate result.

Effects of Chemical Fixatives on Kinetic Measurements of Biomolecular Interaction on Cell Membrane.

Understanding the interaction between ligands and membrane proteins is important for drug design and optimization. Although investigation using live cells is desirable, it is not feasible in some circumstances and cell fixation is performed to reduce cell motion and degradation. This study compared the effects of five fixatives, i.e., formaldehyde vapor (FV), paraformaldehyde (PFA), acetone, methanol, and ethanol, on kinetic measurements via the LigandTracer method. We found that all five fixatives exerted insignificant effects on lectin-glycan interaction. However, antibody-receptor interaction is markedly perturbed by coagulant fixatives. The acetone fixation changed the binding of the anti-human epidermal growth factor receptor 2 (HER2) antibody to HER2 on the cell membrane from a 1:2 to a 1:1 binding model, while methanol and ethanol abolished the antibody binding possibly by removal of the HER2 receptors on the cell membrane. The capability of binding was retained when methanol fixation was performed at lower temperatures, albeit with a binding model of 1:1 instead. Moreover, whereas cell morphology does not exert a substantial impact on lectin-glycan interaction, it can indeed modify the binding model of antibody-receptor interaction. Our results provided insights into the selection of fixatives for cell-based kinetic studies.

Ethanol, Carnoy, and paraformaldehyde as fixative solutions for histological evaluation of preantral follicles in equine ovarian tissue.

The most adequate fixative solution for equine ovarian tissue is still to be determined as a tool to evaluate the improvement of methodological studies in assisted reproductive techniques and fertility preservation. This study aimed to evaluate a short-time ethanol 70% (ST-EtOH, 45 min) exposure as an alternative fixative compared with two classically fixatives [Carnoy's (CAR) solution and paraformaldehyde 4% (PFA)] at different fixation times (6 h, 12 h). The end points evaluated were morphology and classes of preantral follicles, follicular and stromal cell densities, and follicular and oocyte nuclear diameters in equine ovarian tissue. Ovaries (n = 6) from ovariectomized young mares were fragmented (3 × 3 × 1 mm; 20 fragments/ovary) and fixed in the tested treatments. Overall, a total of 11,661 preantral follicles were evaluated in 1444 histological slides. The ST-EtOH similarly preserved the preantral follicle morphometry and stromal cell density compared to the PFA fixative, regardless of the exposure time. Nonetheless, the CAR fixative solution had the greatest percentage of normal preantral follicles and the highest stromal cell density among all treatments. In conclusion, Carnoy's solution must be preferred compared with ST-EtOH and PFA fixatives for studies concerning the cellular morphology of equine ovarian tissue. Moreover, ST-EtOH fixative is a good alternative for equine ovarian tissue when a quick histological evaluation is required instead of more time-consuming and expensive techniques. Additional studies concerning the impact of different fixatives on the ultrastructure of cellular populations and their compatibility with IHC and molecular techniques in equine ovarian tissue are warranted.

Saline dry fixation for improved cell composition analysis using Raman spectroscopy.

Raman spectroscopy enables the label-free assessment of cellular composition. While live cell analysis is the most accurate approach for cellular Raman spectroscopy, the analysis of fixed cells has proved to be very useful, particularly in collaborative projects where samples need to be serially examined by different laboratories or stored and reanalyzed at a later date. However, many chemicals that are widely used for cell fixation directly affect cellular biomolecules, yielding Raman spectra with missing or altered information. In this article, we compared the suitability of dry-fixation with saline versus chemical fixatives. We compared the Raman spectroscopy of saline dry-fixed cells with the more commonly used formaldehyde and methanol fixation and found that dry-fixed cell spectra preserved more cellular information than either chemical fixative. We also assessed the stability of dry-fixed cells over time and found that they were stable for at least 5 months. Finally, a comparison of dry-fixed and live cell spectra revealed effects due to the hydration state of the cells since they were recovered upon rehydrating dry-fixed samples. Thus, for fixed cell Raman spectroscopy, we recommend dry-fixation with unbuffered saline as a superior method to formaldehyde or methanol fixation.

Prevention of mother-to-child transmission of hepatitis B virus: An observation of routine practice in a tertiary liver centre before and after the introduction of the global health sector strategy on viral hepatitis.

INTRODUCTION: Worldwide, around 296 million people have hepatitis B virus (HBV) infection, most commonly transmitted from mother-to-child. Global Health Sector Strategy on Viral Hepatitis (GHSSVH) was introduced in May 2016, calling for elimination of viral hepatitis by 2030. This study aims to compare practice in a tertiary liver centre before and after GHSSVH introduction for prevention of mother-to-child transmission (MTCT). MATERIALS AND METHODS: This retrospective cohort study was performed in a tertiary referral liver centre in Malaysia, using data from electronic medical record from January 2015 to December 2019. A total of 1457 medical records of female with HBV infection were screened. The inclusion criteria of the study were pregnant women with HBsAg positive or known to have HBV infection during the study period. We excluded patients with co-infections of other types of viral hepatitis or human immunodeficiency virus, concurrent liver diseases (e.g.: autoimmune hepatitis, Wilson's disease), previous organ transplant and malignancy­except for hepatocellular carcinoma (HCC). RESULTS: This study included 117 pregnancies and 21/117 (17.9%) were on antiviral therapy (AVT) for HBV. In 2017­ 2019, 13/18 (72.2%) of those with HBV DNA >200,000IU/ml were on AVT, compared to 5/9 (55.6%) for 2015­2016, indicating 58% (95% CI −63% to 568%) higher odds of being on AVT in post GHSSVH group after accounting for HBV DNA. CONCLUSION: Uptake of maternal AVT for the prevention of MTCT shows an increased trend since the introduction of GHSSVH, with room for improvement.

Natural fixatives alternative to formalin in histopathology: A systematic review.

INTRODUCTION: Since constant long-term exposure to formaldehyde endangers the health of laboratory personnel, sugar-based natural products have become interesting alternative fixatives to formaldehyde because of their preservative and antibacterial properties. However, there are controversial findings on the fixative effects of natural fixatives. This study systematically reviews the evidence comparing natural fixatives' types, dilutions, fixative properties and staining quality in normal tissues and histopathological specimens. MATERIALS AND METHODS: A comprehensive search was performed for studies comparing the natural fixatives- and formaldehyde-fixed tissues using databases from inception to January 2022: PubMed, Ovid Medline and Google Scholar. Two independent reviewers did data extraction. The data were pooled for the type of natural fixatives, their concentrations and fixative qualities compared to formaldehyde. RESULTS: Fifteen studies were included in this systematic review. Nine studies used one natural fixative with different dilutions, while six used several natural fixatives to compare their fixative properties with formaldehyde. The most used natural fixative was honey (n = 12) followed by jaggery (n = 8), sugar (n = 3) and others (n = 1). Honey showed the most promising results in fixation and staining, which are compatible with formalin. Jaggery and sugar also showed the possibility of replacing formaldehyde in tissue fixation and staining in smaller tissue samples. CONCLUSION: Natural fixatives showed promising results in tissue fixation. However, optimising the concentrations and conditions of natural fixatives is difficult because of the different chemical constituents and production steps. More comprehensive studies are necessary for application.

The effect of different combinations of fixatives and decalcifying agents on rat and rabbit hard tissues, a guide for histologic processing.

BACKGROUND AND PURPOSE: In order to acquire the best method that can simultaneously maximize tissue morphology and staining quality, we compared the effect of different fixative and decalcifying solutions on the quality of rabbit and rat bone histology. METHOD: Fifty-four rat hemimaxillae and 54 rabbit quarter-parietal bones were allocated into 3 fixation groups (formalin, 10 %sodium-phosphate-buffered-formalin and 10 %calcium-phosphate-buffered-formalin). Each fixative was divided into 6 groups and decalcified with 5 % and 10 % nitric acid (NA), 5 % and 10 % formic acid (FA), Gooding-Stewart liquid (GSL) and EDTA. Slide quality was evaluated on hematoxylin/eosin slides by 3 observers and mean-scores for total-cell-characteristics (TCC) and total-tissue-characteristics (TTC) were statistically analyzed. RESULT: Significant differences in decalcification-time were observed in different combinations of decalcifiers and fixatives in both animals. In rats, TCC was better preserved when using 10 %NA/calcium-phosphate-buffered-formalin compared to 10 %NA/sodium-phosphate-buffered-formalin (P = 0.03). GSL/sodium-phosphate-buffered-formalin performed better than both other fixatives (P < 0.001). TCC differed among the decalcifiers in each of the fixatives. In rabbits, there were differences in TCC among the decalcifiers when formalin (P = 0.001) and sodium-phosphate-buffered-formalin (P = 0.01) were used. TTC only showed significant difference when 10 %FA was used in rats (P = 0.044), with formalin performing better than sodium-phosphate-buffered-formalin (P = 0.01). CONCLUSION: Based on our results, if time is an issue, 10 %NA/calcium-phosphate-buffered-formalin could provide good cellular quality and if time is not a consideration, FA (5 % or 10 %) with sodium-phosphate-buffered-formalin followed by EDTA with formalin, would have the best performance. In rabbits, GSL provides the fastest results, regardless of the fixative and FA/sodium-phosphate-buffered-formalin gives the best cellular quality.

Compounds to mitigate cyanobacterial blooms affect growth and toxicity of Microcystis aeruginosa.

Numerous products and techniques are used to combat harmful cyanobacterial blooms in lakes. In this study, we tested nine products, the phosphate binders Phoslock® and Aqual-PTM, the coagulant chitosan, the phosphorus binder and coagulant aluminum salts (aluminum sulphate and sodium aluminate), the copper-based algicides SeClear, Captain® XTR and CuSO4·5H2O, the antibiotic Streptomycin and the oxidant hydrogen peroxide (H2O2) on their efficiency to manage the cyanobacterium Microcystis aeruginosa (M. aeruginosa). To this end, 7 days of laboratory experiments were conducted and effects were determined on chlorophyll-a, photosystem II efficiency (PSII), soluble reactive phosphorus (SRP) and intracellular and extracellular microcystin (MC) concentrations. The algicides, chitosan and H2O2 were the most powerful in reducing cyanobacteria biomass. Biomass reductions compared to the controls yielded: Chitosan (99.8%) > Hydrogen peroxide (99.6%) > Captain XTR (98.2%) > SeClear (98.1%) > CuSO4·5H2O (97.8%) > Streptomycin (86.6%) > Phoslock® (42.6%) > Aqual-PTM (28.4%) > alum (5.5%). Compounds that caused the largest reductions in biomass also strongly lowered photosystem II efficiency, while the other compounds (Phoslock®, Aqual-PTM, aluminum salts) had no effect on PSII, but strongly reduced SRP. Intracellular MC concentration followed the biomass patterns, extracellular MC was generally lower at higher doses of algicides, chitosan and H2O2 after one week. Recovery of PSII was observed in most algicides and chitosan, but not at the highest doses of SeClear and in all streptomycin treatments. Our results revealed that M. aeruginosa can be killed rapidly using several compounds, that in some treatments already signs of recovery occurred within one week. P fixatives are efficient in reducing SRP, and thus acting via resource suppression, which potentially may provide an addition to fast-acting algicides that kill most of the cells, but allow rapid regrowth as sufficient nutrients remain.

A freeze-substitution approach with solvent-based glyoxal fixative to prevent distortion of ocular structures.

Investigating the function of delicate mammalian eyes often requires chemical fixation, histological sectioning, immunohistochemistry (IHC) and in situ hybridization (ISH). One of the long-standing challenges in the ocular histology field is the limited success of maintaining intact morphology via cryo- or paraffin procedures. Although our latest protocol significantly improved the morphology of mouse eyeball sections, the window technique is time-consuming and requires extensive practice to avoid damage while making windows. In this study, we present a novel glyoxal fixative that is suitable for a freeze-substitution approach to improve both morphology and molecular target preservation of mouse eyes. The method prevents morphology distortion in all tested eyeballs. Therefore, it suits a variety of research needs from morphological examination to investigation of single-molecule RNA expression, using hematoxylin and eosin (H&E) stain, IHC, and ISH assays on either frozen (cryo) or paraffin-infiltrated tissue sections. In addition, this method can be easily performed in many histology laboratories.

Anatomo-comparative study of formaldehyde, alcohol, and saturated salt solution as fixatives in Wistar rat brains.

Although formaldehyde is the most widely used and largely available fixative for preserving cadavers through decomposition prevention, it promotes darkening and weight gain, in addition to being considered carcinogenic. Ethyl alcohol has been proven a potential substitute to formaldehyde due to its effectiveness in tissue penetration, thus preventing proliferation of microorganisms; however, it can only be used alone for fixation of small parts. In view of such fixatives limitations, saturated salt solution has been widely employed based on its antimicrobial effect and ability to maintain tissue similar to the original one, in addition to exerting no hazardous effects as there is no evaporation of harmful substances. This research aimed to observe anatomical brain behaviour submitted to formaldehyde, alcohol, and saturated salt solution as fixatives. Fixatives were tested in 15 adult Wistar rats' brain, submerged in 10 ml of intended solution after removal for 4 weeks. Weight of the brains fixed in saturated salt did not change over the weeks. However, the weight of formaldehyde-fixed brains increased and the weight in alcohol-fixed brains decreased; in addition, modifications in all solutions measures were also observed. Alcohol provides a peculiar dehydrating effect as formaldehyde clearly increases the length of the pieces. Thus, since the saturated salt solution showed no important adjustment over the experimental time, it proved an efficient alternative for replacing formaldehyde and alcohol as fixative solutions of anatomical study of the brain.

Chemical and cryo-collection of muscle samples for transmission electron microscopy using Methacarn and dimethyl sulfoxide✰.

Muscle samples are commonly chemically fixed or frozen immediately upon collection for biochemical and morphological analysis. Certain fixatives such as glutaraldehyde and osmium tetroxide are widely used for transmission electron microscopy (TEM) and lead to adequate preservation of muscle ultrastructure, but do not preserve the molecular features of samples. Methacarn is suggested to be a preferable chemical fixative for light microscopy because it maintains immunohistological features of samples. However, the efficacy of methacarn to preserve ultrastructural features as a primary chemical fixative for TEM is currently unclear. Additionally, cryo-preservation of samples for TEM analysis involves freezing processes such as plunge freezing, slam freezing, or high pressure freezing. High pressure freezing is the considered the gold standard but requires costly equipment and may not be a viable option for many labs collecting tissue samples from remote locations. Dimethyl sulfoxide (DMSO) is a commonly used cryoprotectant that may allow for better structural preservation of samples by impairing ice damage that occurs during plunge/snap freezing. We aimed to assess the effectiveness of methacarn as a primary chemical fixative and determine the effect of pre-coating samples with DMSO before plunge/snap freezing tissues to be prepared for TEM. The micrographs of the methcarn-fixed samples indicate a loss of Z-disk integrity, intermyofibrillar space, mitochondria structure, and lipids. Ultimately, methacarn is not a viable primary fixative for tissue sample preparation for TEM. Similarly, liquid nitrogen freezing of samples wrapped in aluminum foil produced non-uniform Z-disk alignments that appeared smeared with swollen mitochondria. DMSO coating before freezing appears to lessen the alterations to contractile and mitochondrial morphological structures. DMSO appears to be useful for preserving the ultrastructure of sarcomeres if samples are covered before freezing.

Comparación de resultados entre soluciones con y sin formol como medios de fijación y conservación en corazones de Gallus gallus domesticus / Comparison of results between solutions with and without formaldehyde as means of fixation and conservation in Gallus gallus domesticus hearts

RESUMEN: La solución de formol es utilizada en las Escuelas de medicina como medio de fijación y conservación de cadáveres para el estudio de la Anatomía, a la que están expuestos estudiantes, técnicos y personal docente; es alergénica e irritante a las mucosas, y reconocida carcinogénica en humanos por International Agency for Research on Cancer (2006). El objetivo del presente estudio fue comparar resultados cuantitativos y cualitativos entre corazones de Gallus gallus domesticus, luego de aplicarles soluciones con y sin formol. Se formaron dos grupos al azar, a uno se le aplicó solución de formol al 10 %, y al otro solución libre de formol. Se realizaron medidas antropométricas, organolépticas, y de fotografía (Pretest, durante y Postest). Se elaboró base datos en Microsoft Excel (2019), y su procesamiento en SPSS Statistics 2017 Versión 25. Para variables cuantitativas se aplicó la prueba de Shapiro-Wilk, y t-Student pareada. Para variables cualitativas el test Alfa de Cronbach, Chi cuadrado (X2) y los correspondientes coeficientes de asociación (D de Somers y Tau b de Kendal). Los resultados obtenidos de las variables peso, largo, y altura presentaron diferencia estadística significativa (p-valor <0,05), siendo diferente para el ancho y grosor de la pared del ventrículo izquierdo. Las variables color y consistencia presentaron diferencias significativa (p-valor <0,05). El olor irritante a las mucosas estuvo presente durante todo el estudio con la solución con formol. A la inspección, ninguno de los dos grupos presento colonización - descomposición. Se concluye que, los órganos en experimentación que se les aplicó solución libre de formol, presentaron mejores resultados con respecto a los que se les aplico formol al 10 %.

SUMMARY: The formaldehyde solution is used in medical schools as a means of fixing and preserving corpses for the study of Anatomy, to which students, technicians and teaching personnel are exposed; it is allergenic and irritant to the mucosa, and recognized as a human carcinogen by the International Agency for Research on Cancer (2006). The objective of the present study was to compare quantitative and qualitative results between Gallus gallus domesticus hearts, after applying solutions with and without formaldehyde. Two groups were formed at random, to one a 10 % formaldehyde solution was applied, and to the other formaldehyde- free solution. Anthropometric, organoleptic, and photographic measurements were carried out (Pretest, during and Posttest). A database was prepared in Microsoft Excel (2019), and its processing in SPSS Statistics 2017 Version 25. For quantitative variables, the Shapiro-Wilk test and t-Student paired were applied. For qualitative variables the Cronbach's Alpha test, Chi square (X2) and the corresponding association coefficients (Somers D and Kendal's Tau b). The results obtained from the variables weight, length, and height presented a statistically significant difference (p-value <0.05), being different for the width and thickness of the left ventricular wall. The variables color and consistency showed significant differences (p-value <0.05). The irritating smell to the mucous membranes was present throughout the study with the formaldehyde solution. Upon inspection, neither group showed colonization - decomposition. It is concluded that the organs in experimentation that were applied formaldehyde-free solution presented better results compared to those that were applied 10 % formaldehyde.

Development of a fixative protocol using formaldehyde and gluteraldehyde for preservation of microbial art on agar plates.

AIMS: Agar art bridges the gap between science and art using microbes instead of paint. Afterwards, the art can change in response to microbial fluctuation, meaning preservation of the original art is essential. Here, formaldehyde and glutaraldehyde were investigated as preservatives, involving techniques used in healthcare settings to preserve samples. METHODS AND RESULTS: Formaldehyde was tested at 1.0%, 2.0% and 3.7%, w/v, whereas glutaraldehyde was tested at 1% and 2.5%, w/v. Both compounds and respective concentrations were tested for different time periods. Escherichia coli, Serratia marcescens, Staphlococcus aureus and Micrococcus luteus were used as bacteria for "drawing" the works of art. The effectiveness of fixation was determined using integrated densities and visual assessment. Initially, both compounds showed potential promise, albeit with a loss of bacteria. Ser. marcescens was prone to colour changes and glutaraldehyde caused discolouration of agar and bacteria. These could be caused by a pH decrease in the agar, due to residual free aldehyde groups. Reduction of this was tested using 300 mM sodium metabisulfite to neutralize excess aldehydes. This initially led to reduced bacterial loss and avoided colour changes, however measurements 24 h post-fixation showed colour loss to some bacterial clusters. CONCLUSIONS: Here, at least 2% formaldehyde for a short fixation period, typically 1 min, depending on the species, was most promising for the preservation of art. Given the success of this with different bacteria, it would make a good starting combination for anyone trying to fix agar art, although methodology refinement may be needed for optimisation depending on the bacterial species used. SIGNIFICANCE AND IMPACT OF STUDY: This study shows, for the first time, successful fixation and preservation of different bacterial species on agar. The impact of this is to preserve agar art while making it safe and non-infective to those in contact with the microbial art.

Glyoxal fixation: an immunohistochemistry assay evaluation.

Analysis of surgical pathology specimens by histological techniques including immunohistochemistry (IHC) assays is a mainstay of disease diagnosis in humans. Neutral buffered formalin (NBF) is currently the primary fixative used, but its use is not without risks due to toxicity and carcinogenicity. Several glyoxal-based fixatives have been commercially produced, are considered safer alternatives to NBF, and produce histochemical staining results comparable to that of tissues fixed in NBF. However, previous studies evaluating IHC assay results in tissues fixed in NBF and glyoxal solutions have indicated mixed results. This study demonstrated that while tissues fixed in NBF were slightly superior to tissues fixed in glyoxal solutions among the 34 antibodies assayed with IHC, all fixative solutions produced results compatible for use in an anatomic pathology laboratory.

Formalin-fixed paraffin-embedded tissues for microbiome analysis in rainbow trout (Oncorhynchus mykiss).

The gut microbiomes of rainbow trout (Oncorhynchus mykiss) reared at 16° and 22 °C were determined using formalin-fixed paraffin-embedded tissues (FFPE) and compared to fresh frozen tissue. The data revealed microbiomes could be successfully determined using FFPE tissue opening a new horizon in studying intestinal microbiota using archived histological samples.

Effect of formalin fixation on measured concentrations of deposited gadolinium in human tissue: an autopsy study.

BACKGROUND: Generally, studies of gadolinium (Gd) deposition in humans measure concentration by analyzing formalin fixed postmortem tissue. However, the effect of formalin fixation on measured Gd concentration has not been well investigated. PURPOSE: To evaluate the effect of fixation by comparing Gd concentration in fresh versus formalin-fixed postmortem human tissues. MATERIAL AND METHODS: Fresh samples of bone and skin were collected from autopsy cases with previous exposure to Gd-based contrast agents (GBCAs). The type of GBCA administered, dose, and estimated glomerular filtration rate were recorded. Each tissue sample was cut into three aliquots. Paired samples were stored fresh frozen while the remaining two were stored in 10% neutral buffered formalin for one and three months, respectively. Gd concentration was measured using ICP-MS. RESULTS: Of 18 autopsy cases studied, 12 were exposed to only macrocyclic GBCA, one to only linear agents, and five received both macrocyclic and linear agents. On average, Gd concentration for bone decreased 30.7% after one month of fixation (P = 0.043) compared to non-fixed values. There was minimal, if any, change in concentration between one and three months (average decrease 1.5%; P = 0.89). The findings were numerically similar for skin tissue with an average decrease of 36.9% after one month (P = 0.11) and 6.0% (P = 0.73) between one and three months. CONCLUSION: Formalin fixation appears to decrease Gd concentration in bone and skin by approximately 30%-40% on average. The largest decrease occurs within the first 30 days of fixation followed by a considerably smaller decrease at 60 days.

Interference of fixatives and fixation period on the morphologic analysis of ovarian preantral follicles.

Ovine ovarian fragments (3 × 3 × 1 mm) were fixed in neutral buffered formalin (NBF), Carnoy's solution (CAR), Davidson's solution (DAV), or paraformaldehyde (PFA) for 12 h or 24 h. After this fixation time, each fragment was prepared for histological analysis. Although fixative and fixation period did not affect follicular and stromal cells density, the percentages of morphologically normal primordial and primary follicles was affected by the fixative type and period of fixation. Paraformaldehyde was not indicated as a fixative for ovarian fragments. Formalin was a suitable fixative only when the period of fixation was 12 h, while Carnoy was efficient after a fixation period of 24 h. In conclusion, the most indicated fixative for the morphological evaluation of ovarian preantral follicles was DAV, regardless of the fixation period, that is 12 or 24 h.

Neutrophil fixation protocols suitable for substrates to detect anti-neutrophil cytoplasmic antibodies by indirect immunofluorescence.

Anti-neutrophil cytoplasmic antibodies (ANCAs) are autoantibodies that recognize neutrophil cytoplasmic antigens. The major ANCA antigens are myeloperoxidase and proteinase 3. Necrotizing small vessel vasculitis accompanied by ANCA production is called ANCA-associated vasculitis (AAV). In addition to AAV, ANCA is sometimes produced in patients with connective tissue diseases, such as systemic lupus erythematosus, and inflammatory bowel diseases. Indirect immunofluorescence (IIF) and enzyme immunoassay (EIA) have been used to detect ANCAs. Recently, the accuracy of EIA has improved and it has become the gold standard for ANCA detection. However, IIF does not lose its role in ANCA detection because EIA cannot detect ANCAs that recognize antigens other than those coated on the plate. For IIF, neutrophil substrates prepared with two different fixations, namely, ethanol fixation and formalin fixation, are used. There is a recommended protocol for ethanol fixation but not for formalin fixation. This study prepared neutrophil substrates according to the recommended protocol for ethanol fixation and protocols in the literature and original protocols for formalin fixation and then examined ANCA specificity and how storage period would influence the number of cells, antigen distribution, and antigenicity of the substrates. As a result, the number of cells and antigen distribution did not change after storage for up to 2 months regardless of fixation protocols, whereas a time-dependent decline in ANCA antigenicity and a fixation protocol-dependent difference in ANCA specificity were observed. How neutrophils are fixed on the glass slide needs to be checked upon evaluation of ANCAs by IIF.

Neutralisation of SARS-CoV-2 by anatomical embalming solutions.

Teaching and learning anatomy by using human cadaveric specimens has been a foundation of medical and biomedical teaching for hundreds of years. Therefore, the majority of institutions that teach topographical anatomy rely on body donation programmes to provide specimens for both undergraduate and postgraduate teaching of gross anatomy. The COVID-19 pandemic has posed an unprecedented challenge to anatomy teaching because of the suspension of donor acceptance at most institutions. This was largely due to concerns about the potential transmissibility of the SARS-CoV-2 virus and the absence of data about the ability of embalming solutions to neutralise the virus. Twenty embalming solutions commonly used in institutions in the United Kingdom and Ireland were tested for their ability to neutralise SARS-CoV-2, using an established cytotoxicity assay. All embalming solutions tested neutralised SARS-CoV-2, with the majority of solutions being effective at high-working dilutions. These results suggest that successful embalming with the tested solutions can neutralise the SARS-CoV-2 virus, thereby facilitating the safe resumption of body donation programmes and cadaveric anatomy teaching.