Investigation of the use of gelatine-glycerine and gelatine-polyvinyl alcohol mixtures as tissue consistency preservatives in cadavers fixed with modified SEFS solution

This study aimed to improve the effectiveness of SEFS, a fixing solution composed of soap and ethanol. This was achieved by modifying the formulation of SEFS. Additionally, this study aimed to preserve the consistency of organs by perfusing cadavers with mixtures of gelatine-glycerin (gelatine-Gls) and gelatine-polyvinyl alcohol (gelatine-PVA) through vascular access. The modified SEFS embalmed cadavers were divided into two groups: Group I was treated with gelatine-glycerin, and Group II was treated with gelatine-polyvinyl alcohol and each group comprised of two goats and three rabbits. Over one year, cadavers were objectively assessed for hardness, colour, and joint range of motion. Additionally, the cadavers were subjectively evaluated after dissection and palpation. For the modified SEFS embalmment haptic and optic examinations of the muscles revealed they maintained a vivid colour tone, closely resembling their natural colour. The thoracic organs displayed natural colour, with the lungs retaining their shape without collapse. Notably, the walls of the atrium and ventricles of the heart remained intact without inward collapse. The use of gelatine-PVA yielded better outcomes than gelatine-Gls in preserving the volumes of both chest and abdominal organs. This was particularly evident in the heart, lungs, liver, spleen, and kidney. Overall, the modified SEFS and gelatin-PVA mixtures were superior in maintaining certain properties better than expected from cadavers.

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.

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.

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.

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.

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 malignancy—except 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 2015–2016, 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.

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.

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-P^TM, 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-P^TM (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-P^TM, 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.

Universal NicE-seq for high-resolution accessible chromatin profiling for formaldehyde-fixed and FFPE tissues

Accessible chromatin plays a central role in gene expression and chromatin architecture. Current accessible chromatin approaches depend on limited digestion/cutting and pasting adaptors at the accessible DNA, thus requiring additional materials and time for optimization. Universal NicE-seq (UniNicE-seq) is an improved accessible chromatin profiling method that negates the optimization step and is suited to a variety of mammalian cells and tissues. Addition of 5-methyldeoxycytidine triphosphate during accessible chromatin labeling and an on-bead library making step substantially improved the signal to noise ratio while protecting the accessible regions from repeated nicking in cell lines, mouse T cells, mouse kidney, and human frozen tissue sections. We also demonstrate one tube UniNicE-seq for the FFPE tissue section for direct NGS library preparation without sonication and DNA purification steps. These refinements allowed reliable mapping of accessible chromatin for high-resolution genomic feature studies.

Measurement and visualization of cell membrane surface charge in fixed cultured cells related with cell morphology

The diagnosis of patients with malignancies relies on the results of a clinical cytological examination. To enhance the diagnostic qualities of cytological examinations, it is important to have a detailed analysis of the cell’s characteristics. There is, therefore, a need for developing a new auxiliary method for cytological diagnosis. In this study, we focused on studying the charge of the cell membrane surface of fixed cells, which is one of important cell’s characteristics. Although fixed cells lose membrane potential which is observed in living cells owing to ion dynamics, we hypothesized that fixed cells still have a cell membrane surface charge due to cell membrane components and structure. We used 5 cell lines in this study (ARO, C32TG, RT4, TK, UM-UC-14). After fixation with CytoRich Red, we measured the cell membrane surface charge of fixed cells in solution using zeta potential measurements and fixed cells on glass slides, visualizing it using antibody-labeled beads and positively-charged beads. Furthermore, we measured the cell membrane surface charge of fixed cells under different conditions, such as different solution of fixative, ion concentration, pH, and pepsin treatments. The zeta potential measurements and visualization using the beads indicated that the cell membrane surface of fixed cells was negatively charged, and also that the charge varied among fixed cells. The charge state was affected by the different treatments. Moreover, the number of cell-bound beads was small in interphase, anaphase, and apoptotic cells. We concluded that the negative cell membrane surface charge was influenced by the three-dimensional structure of proteins as well as the different types of amino acids and lipids on the cell membrane. Thus, cell surface charge visualization can be applied as a new auxiliary method for clinical cytological diagnosis. This is the first systematic report of the cell membrane surface charge of fixed cells.

Cytologic evaluation of p16 staining in head and neck squamous cell carcinoma in CytoLyt versus formalin-fixed material

BACKGROUND

The management of high-risk human papillomavirus (HR-HPV)-related oropharyngeal head and neck squamous cell carcinomas (HNSCCs) are distinct from HNSCC linked to smoking and alcohol use. HR-HPV-positive HNSCC frequently presents as a cervical lymph node metastasis. Because fine-needle aspiration (FNA) is often the initial diagnostic procedure, evaluating HR-HPV status in cytology specimens is important. The overexpression of p16 is a surrogate for HR-HPV; however, the evaluation of p16 in FNAs remains controversial.

METHODS

From September 2015 to December 2016, cytopathologists performed 25 FNAs of neck lymph nodes that were suspicious for HR-HPV-positive HNSCC. Initial passes produced smears for on-site evaluation and CytoLyt material. Additional passes were formalin-fixed. A CytoLyt cell block (CCB) and a formalin-fixed cell block (FFCB) were prepared, and p16 immunocytochemistry was performed.

RESULTS

In 24 of 25 cases, the FFCB had diffuse (≥70% of cells), strong nuclear/cytoplasmic p16 staining. In all 24 of these cases, HR-HPV was detected by in situ hybridization. The corresponding CCB had weak-to-moderate p16 staining in <70% of cells (range, 5%-60% of cells) in 17 cases, 4 had weak-to-moderate diffuse staining, and 4 were acellular. The percentage of p16-positive cells was significantly higher with FFCB than with CCB (formalin: 94% ± 2%; CytoLyt, 38% ± 7%; 2-tailed, paired Student t test; P < .001; Fisher exact test, P < .001).

CONCLUSIONS

The fixative used had a drastic impact on p16 staining, which explained the staining variability reported in the literature. FFCBs show a diffuse staining pattern, which correlates with HR-HPV status, whereas CCBs show a weaker and inconsistent staining pattern, which is more difficult to interpret.

Comparison of Two Laboratory Methods of Preservation for Preclinical Preparation of Bovine Aortic Heart Valve Suitable for Human Use

The present experimental study was carried out as an experimental study in the department of Cardiac Surgery at Bangabandhu Sheikh Mujib Medical University, Dhaka, Bangladesh from July 2011 to May 2013 to see which preservation techniques give us morphologically and histologically suitable xenograft heart valve for clinical use. We reviewed 20 bovine aortic valves in 2 years. Each of 10 samples was grouped as glutaraldehyde (1.5%) preservation and cryopreservation (-180°C). After collecting each specimen, sterilization of valve was done in low concentration of sterile antibiotic solution (CLPVA). Then 10 dissected valves were immersed each in 250ml of 1.5% glutaraldehyde solution at 4°C. Another 10 dissected valves were placed in a solution of 100ml 10% DMSO and suspended in vapor phase of liquid nitrogen at -180°C. Then after 4 weeks, the valves were examined for naked eye (color change, shrinkage, swelling, pliability, stiffness of leaflet) and histological (endothelial cells, leaflet extracellular matrix preservation, fibroblast preservation, inflammation, necrosis and other pathological conditions on valve leaflet) examination. Statistical analysis showed that morphological changes were not significant in both groups but in histological examination, cryopreservation showed effective preservation of fibroblast and extracellular matrix than glutaraldehyde preservation.

Optimization of fixative solution for retinal morphology: a comparison with Davidson's fixative and other fixation solutions

PURPOSE

Numerous fixative solutions are available but many are not amenable to the histomorphological preservation of retinae. The investigators specifically focused on retinal histological studies, which rather than 4% formaldehyde (FA), often use Davidson's fixative. However the latter has its limitations. The purpose of this study was to produce a new fixative which maintains retinae closer to the in vivo conditions.

STUDY DESIGN

Experimental design.

METHODS

Four fixative formulations (4% paraformaldehyde, Davidson's fixative, modified Davidson's fixative and an in-house fixative - TB-Fix) were tested on retinae and the outcomes on histomorphology and immunohistochemical staining for selected antigenic markers was compared.

RESULTS

TB-Fix markedly improved morphological detail following hematoxylin and eosin staining, most importantly eliminating the spongiform appearance in the plexiform layer and the swelling of somata (including Müller cells), when compared to FA, Davidson's fixative and its modified version. Retinal samples fixed with TB-Fix or FA showed comparable results in immunohistological staining for neurons and glia in the retina. Importantly, while the whole eye fixed with FA collapsed in shape and induced artificial retinal detachment, the eye fixed with TB-Fix avoided deformation and detachment. Furthermore, we found that TB-Fix also prevented detachment from the culture plate when used to fix HEK293 cells, which are known to detach from the plate easily.

CONCLUSION

It was demonstrated that TB-Fix provides an overall improvement in the preservation of retinal morphology and chemical composition.

Penetration of formaldehyde based fixatives into heart

OBJECTIVES

To investigate the penetration depth of formaldehyde-based fixatives into cardiac muscle samples over the course of fixation.

BACKGROUND

Fixation is the essential step in anatomical studies. However, very little is known about penetration of most common fixatives into cardiac tissue.

METHODS

A total of 40 heart samples were investigated. 4 study groups (n=10 in each case) were formed in such manner they differed only in concentration and type of fixative (1) - 2% formaldehyde phosphate-buffered solution (FPBS); (2) - 4% FPBS (formalin); (3) - 10% FPBS; (4) - alcoholic formalin. Samples were measured before fixation and in the following time points: 24 hours, 72 hours, 168 hours.

RESULTS

The penetration depth differed significantly among studied fixatives (p<0.0001). 100% penetration occurred in all samples after 72 hours in alcoholic formalin solution and after 168 hours in 10% FPBS. After alcoholic formalin fixation, the tissue is more brittle and sub-epicardial blisters were observed in some cases.

CONCLUSIONS

Alcoholic formalin solution is the fastest fixative among the studied ones, however it has several adverse effects on tissue structure. It was found that 10% FPBS is the best and a relatively fast fixative for cardiac morphometric studies.

Pathogen Inactivating Properties and Increased Sensitivity in Molecular Diagnostics by PAXgene, a Novel Non-Crosslinking Tissue Fixative

Background

Requirements on tissue fixatives are getting more demanding as molecular analysis becomes increasingly relevant for routine diagnostics. Buffered formaldehyde in pathology laboratories for tissue fixation is known to cause chemical modifications of biomolecules which affect molecular testing. A novel non-crosslinking tissue preservation technology, PAXgene Tissue (PAXgene), was developed to preserve the integrity of nucleic acids in a comparable way to cryopreservation and also to preserve morphological features comparable to those of formalin fixed samples.

Methods

Because of the excellent preservation of biomolecules by PAXgene we investigated its pathogen inactivation ability and biosafety in comparison to formalin by in-vitro testing of bacteria, human relevant fungi and human cytomegalovirus (CMV). Guidelines for testing disinfectants served as reference for inactivation assays. Furthermore, we tested the properties of PAXgene for detection of pathogens by PCR based assays.

Results

All microorganisms tested were similarly inactivated by PAXgene and formalin except Clostridium sporogenes, which remained viable in seven out of ten assays after PAXgene treatment and in three out of ten assays after formalin fixation. The findings suggest that similar biosafety measures can be applied for PAXgene and formalin fixed samples. Detection of pathogens in PCR-based diagnostics using two CMV assays resulted in a reduction of four to ten quantification cycles of PAXgene treated samples which is a remarkable increase of sensitivity.

Conclusion

PAXgene fixation might be superior to formalin fixation when molecular diagnostics and highly sensitive detection of pathogens is required in parallel to morphology assessment.

The Immune Responses and Calcification of Bioprostheses in the α1,3-Galactosyltransferase Knockout Mouse

BACKGROUND

The study aim was to evaluate the immune reaction, difference of degenerative calcification, and anti-calcification effect of decellularization with or without α-galactosidase in bovine pericardium and porcine heart valves, using an α1,3-galactosyltransferase (α-Gal) knockout (KO) mouse model.

METHODS

In order to elucidate the anti-calcification effect of decellularization with or without α-galactosidase, bovine pericardium and porcine heart valve tissues were assigned to four groups according to the tissue preparation method: (i) glutaraldehyde (GA) fixation only; (ii) decellularization + GA fixation (Decell); (iii) α-galactosidase + GA fixation (α-galactosidase); and (iv) decellularization +α-galactosidase + GA fixation (Decell + α-galactosidase). Each prepared tissue was implanted subcutaneously into α-Gal KO mice. Anti-α-Gal immunoglobulin (Ig) G and IgM antibody titers were monitored prior to implantation and at four, eight and 12 weeks after implantation using an enzyme-linked immunosorbent assay. Calcium contents of explanted tissues were measured at 12 weeks after implantation.

RESULTS

There were no significant differences in the anti-α-Gal IgG antibody titers according to the type of bioprosthetic material or tissue preparation method (p >0.05). The calcium content was significantly lower in porcine heart valves than in bovine pericardium when implanted in α-Gal-KO mice (p <0.001). Calcium contents in bovine pericardium and porcine heart valves were significantly lower in the Decell, α-galactosidase and Decell + α-galactosidase groups than in the GA group (all p <0.05).

CONCLUSIONS

The porcine heart valve induced lower levels of calcium deposition than did the bovine pericardium, but the anti-α-Gal IgG antibody titers did not differ significantly between the bioprosthetic tissues. Decellularization had significant anticalcification effects in both the bovine pericardium and porcine heart valves, though there was no significant difference in the anti-α-Gal IgG antibody titers among tissue preparation methods.

Fixation strategies for retinal immunohistochemistry

Immunohistochemical and ex vivo anatomical studies have provided many glimpses of the variety, distribution, and signaling components of vertebrate retinal neurons. The beauty of numerous images published to date, and the qualitative and quantitative information they provide, indicate that these approaches are fundamentally useful. However, obtaining these images entailed tissue handling and exposure to chemical solutions that differ from normal extracellular fluid in composition, temperature, and osmolarity. Because the differences are large enough to alter intercellular and intracellular signaling in neurons, and because retinae are susceptible to crush, shear, and fray, it is natural to wonder if immunohistochemical and anatomical methods disturb or damage the cells they are designed to examine. Tissue fixation is typically incorporated to guard against this damage and is therefore critically important to the quality and significance of the harvested data. Here, we describe mechanisms of fixation; advantages and disadvantages of using formaldehyde and glutaraldehyde as fixatives during immunohistochemistry; and modifications of widely used protocols that have recently been found to improve cell shape preservation and immunostaining patterns, especially in proximal retinal neurons.

Paraformaldehyde Fixation May Lead to Misinterpretation of the Subcellular Localization of Plant High Mobility Group Box Proteins

Arabidopsis High Mobility Group Box (HMBG) proteins were previously found associated with the interphase chromatin but not the metaphase chromosome. However, these studies are usually based on immunolocalization analysis involving paraformaldehyde fixation. Paraformaldehyde fixation has been widely adapted to preserved cell morphology before immunofluorescence staining. On one hand, the processed cells are no longer living. On the other hand, the processing may lead to misinterpretation of localization. HMGBs from Arabidopsis were fused with enhanced green fluorescence protein (EGFP) and transformed into tobacco BY-2 cells. Basically, the localization of these HMGB proteins detected with EGFP fluorescence in interphase agreed with previous publications. Upon 4% paraformaldehyde fixation, AtHMGB1 was found associated with interphase but not the metaphase chromosomes as previously reported. However, when EGFP fluorescence signal was directly observed under confocal microscope without fixation, association of AtHMGB1 with metaphase chromosomes can be detected. Paraformaldehyde fixation led to dissociation of EGFP tagged AtHMBG1 protein from metaphase chromosomes. This kind of pre-processing of live specimen may lead to dissociation of protein-protein or protein-nucleic acid interaction. Therefore, using of EGFP fusion proteins in live specimen is a better way to determine the correct localization and interaction of proteins.

Determining optimal ultrasound off time with micropulse longitudinal phacoemulsification

PURPOSE

To evaluate the optimum off time for the most efficient removal of lens fragments using micropulse ultrasound (US).

SETTING

John A. Moran Eye Center Laboratories, University of Utah, Salt Lake City, Utah, USA.

DESIGN

Experimental study.

METHODS

Porcine lens nuclei were soaked in formalin for 2 hours and then cut into 2.0 mm cubes using the Signature US machine with a bent 0.9 mm phaco tip with a 30-degree bevel. The on time was 7 milliseconds (ms), and the off time was varied from 2 to 20 ms in 2 ms steps. Phacoemulsification efficiency (time for fragment removal) and chatter (number of times the fragment bounced from the tip) were measured.

RESULTS

A nonsignificant linear increase in efficiency was observed with 2 to 6 ms of off time (R(2) = .87, P = .24). A significant linear decrease in efficiency was observed with 6 to 20 ms (R(2) = .74, P = .006).

CONCLUSIONS

With micropulse longitudinal US, 6 to 7 ms of off time was as efficient as shorter off times; longer off times (8 to 20 ms) showed decreased efficiency. Chatter was minimal and statistically similar throughout. To maximize phacoemulsification US efficiency, an off-time setting of 6 ms is recommended.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

Sequestration Revisited: Integrating Traditional Electron Microscopy, De Novo Assembly and New Results

Electron microscopy analysis of the autophagic sequestration membrane (SM) in various metazoan cell types after different fixation methods shows that: (1) the growing SM cannot derive from preformed rough surfaced endoplasmic reticulum (RER) membranes by transformation; (2) the empty cleft between the two layers of the SM after aldehyde fixation is an artifact of sample preparation; (3) the SM emerges from and grows de novo in cytoplasmic areas where membranous precursors cannot be identified by traditional electron microscopy; (4) the growing SM consists of two tightly packed membrane layers with a sharp bend at the edge; (5) changes in the environment of the growing SM participate in the determination of the size and shape of the autophagosome. We suggest that expansion as well as regression takes place at the edge of the growing SM. Stabilization and irreversibility of formation of the SM is achieved by closure. The immediate source of lipids for the SM must be in the cytoplasmic matrix, supposedly in the form of special phospholipid carrying vesicles that might involve the transmembrane Atg9 protein. To explain the apparent lack of such vesicles by electron microscopy we suggest that they are too small, have a similar density to other frequently occurring structures, or are destroyed during sample preparation.

Aβ seeds resist inactivation by formaldehyde

Cerebral β-amyloidosis can be exogenously induced by the intracerebral injection of brain extracts containing aggregated β-amyloid (Aβ) into young, pre-depositing Aβ precursor protein- (APP) transgenic mice. Previous work has shown that the induction involves a prion-like seeding mechanism in which the seeding agent is aggregated Aβ itself. Here we report that the β-amyloid-inducing activity of Alzheimer's disease (AD) brain tissue or aged APP-transgenic mouse brain tissue is preserved, albeit with reduced efficacy, after formaldehyde fixation. Moreover, spectral analysis with amyloid conformation-sensitive luminescent conjugated oligothiophene dyes reveals that the strain-like properties of aggregated Aβ are maintained in fixed tissues. The resistance of Aβ seeds to inactivation and structural modification by formaldehyde underscores their remarkable durability, which in turn may contribute to their persistence and spread within the body. The present findings can be exploited to establish the relationship between the molecular structure of Aβ aggregates and the variable clinical features and disease progression of AD even in archived, formalin-fixed autopsy material.

Mouse tissue fixation

One of the primary goals of fixation is to stop postmortem changes that degrade the tissue and allow optimal preservation of morphologic and cytological detail as well as nucleic acid integrity. Following death, tissues soon undergo autolysis, and if organisms from the gastrointestinal, urinary, or respiratory tracts are present, their colonization can soon cause putrefaction. Time is of the essence because warmer temperatures accelerate both types of degradation. Placing the tissue into a fixative stops the postmortem changes. Fixatives have their effect on tissue by cross-linking, coagulation, or a combination of both. This article outlines the basic tissue fixation procedure and offers guidance on choosing an appropriate fixative, the timing and duration of fixation, sample storage, and quality issues.

Inactivation and ultrastructure analysis of Bacillus spp. and Clostridium perfringens spores

Bacterial endospores are resistant to many environmental factors from temperature extremes to ultraviolet irradiation and are generally more difficult to inactivate or kill than vegetative bacterial cells. It is often considered necessary to treat spores or samples containing spores with chemical fixative solutions for prolonged periods of time (e.g., 1-21 days) to achieve fixation/inactivation to enable electron microscopy (EM) examination outside of containment laboratories. Prolonged exposure to chemical fixatives, however, can alter the ultrastructure of spores for EM analyses. This study was undertaken to determine the minimum amount of time required to inactivate/sterilize and fix spore preparations from several bacterial species using a universal fixative solution for EM that maintains the ultrastructural integrity of the spores. We show that a solution of 4% paraformaldehyde with 1% glutaraldehyde inactivated spore preparations of Bacillus anthracis, Bacillus cereus, Bacillus megaterium, Bacillus thuringiensis, and Clostridium perfringens in 30 min, and Bacillus subtilis in 240 min. These results suggest that this fixative solution can be used to inactivate and fix spores from several major groups of bacterial spore formers after 240 min, enabling the fixed preparations to be removed from biocontainment and safely analyzed by EM outside of biocontainment.

ERK MAP kinase activation in spinal cord regulates phosphorylation of Cdk5 at serine 159 and contributes to peripheral inflammation induced pain/hypersensitivity

Cyclin-dependent kinase 5 is a proline-directed serine/threonine kinase and its activity participates in the regulation of nociceptive signaling. Like binding with the activators (P35 or P25), the phosphorylation of Cdk5 plays a critical role in Cdk5 activation. However, it is still unclear whether Cdk5 phosphorylation (p-Cdk5) contributes to pain hyperalgesia. The aim of our current study was to identify the roles of p-Cdk5 and its upstream regulator in response to peripheral inflammation. Complete Freund's adjuvant (CFA) injection induced acute peripheral inflammation and heat hyperalgesia, which was accompanied by sustained increases in phospho-ERK1/2 (p-ERK1/2) and phospho-Cdk5^S159 (p-Cdk5^S159) in the spinal cord dorsal horn (SCDH). CFA-induced p-ERK primarily colocalized with p-Cdk5^S159 in superficial dorsal horn neurons. Levels in p-ERK and p-Cdk5 were also increased in the 2^nd phase of hyperalgesia induced by formalin injection, which can produce acute and tonic inflammatory pain. MAP kinase kinase inhibitor U0126 intrathecal delivery significantly suppressed the elevation of p-Cdk5^S159, Cdk5 activity and pain response behavior (Heat hyperalgesia, Spontaneous flinches) induced by CFA or formalin injection. Cdk5 inhibitor roscovitine intrathecal administration also suppressed CFA-induced heat hyperalgesia and Cdk5 phosphorylation, but did not attenuate ERK activation. All these findings suggested that p-Cdk5^S159 regulated by ERK pathway activity may be a critical mechanism involved in the activation of Cdk5 in nociceptive spinal neurons contributes to peripheral inflammatory pain hypersensitivity.

Mechanical compliance and immunological compatibility of fixative-free decellularized/cryopreserved human pericardium

BACKGROUND

The pericardial tissue is commonly used to produce bio-prosthetic cardiac valves and patches in cardiac surgery. The procedures adopted to prepare this tissue consist in treatment with aldehydes, which do not prevent post-graft tissue calcification due to incomplete xeno-antigens removal. The adoption of fixative-free decellularization protocols has been therefore suggested to overcome this limitation. Although promising, the decellularized pericardium has not yet used in clinics, due to the absence of proofs indicating that the decellularization and cryopreservation procedures can effectively preserve the mechanical properties and the immunologic compatibility of the tissue.

PRINCIPAL FINDINGS

The aim of the present work was to validate a procedure to prepare decellularized/cryopreserved human pericardium which may be implemented into cardiovascular homograft tissue Banks. The method employed to decellularize the tissue completely removed the cells without affecting ECM structure; furthermore, uniaxial tensile loading tests revealed an equivalent resistance of the decellularized tissue to strain, before and after the cryopreservation, in comparison with the fresh tissue. Finally, immunological compatibility, showed a minimized host immune cells invasion and low levels of systemic inflammation, as assessed by tissue transplantation into immune-competent mice.

CONCLUSIONS

Our results indicate, for the first time, that fixative-free decellularized pericardium from cadaveric tissue donors can be banked according to Tissue Repository-approved procedures without compromising its mechanical properties and immunological tolerance. This tissue can be therefore treated as a safe homograft for cardiac surgery.

Enhanced stability of microRNA expression facilitates classification of FFPE tumour samples exhibiting near total mRNA degradation

BACKGROUND

As degradation of formalin-fixed paraffin-embedded (FFPE) samples limits the ability to profile mRNA expression, we explored factors predicting the success of mRNA expression profiling of FFPE material and investigated an approach to overcome the limitation.

METHODS

Bladder (n=140, stored 3-8 years) and cervix (n=160, stored 8-23 years) carcinoma FFPE samples were hybridised to Affymetrix Exon 1.0ST arrays. Percentage detection above background (%DABG) measured technical success. Biological signal was assessed by distinguishing cervix squamous cell carcinoma (SCC) and adenocarcinoma (AC) using a gene signature. As miR-205 had been identified as a marker of SCC, precursor mir-205 was measured by Exon array and mature miR-205 by qRT-PCR. Genome-wide microRNA (miRNA) expression (Affymetrix miRNA v2.0 arrays) was compared in eight newer FFPE samples with biological signal and eight older samples without.

RESULTS

RNA quality controls (QCs) (e.g., RNA integrity (RIN) number) failed to predict profiling success, but sample age correlated with %DABG in bladder (R=-0.30, P<0.01) and cervix (R=-0.69, P<0.01). Biological signal was lost in older samples and neither a signature nor precursor mir-205 separated samples by histology. miR-205 qRT-PCR discriminated SCC from AC, validated by miRNA profiling (26-fold higher in SCC; P=1.10 × 10(-5)). Genome-wide miRNA (R=0.95) and small nucleolar RNA (R=0.97) expression correlated well in the eight newer vs older FFPE samples and better than mRNA expression (R=0.72).

CONCLUSION

Sample age is the best predictor of successful mRNA profiling of FFPE material, and miRNA profiling overcomes the limitation of age and copes well with older samples.

Chromatin composition is changed by poly(ADP-ribosyl)ation during chromatin immunoprecipitation

Chromatin-immunoprecipitation (ChIP) employs generally a mild formaldehyde cross-linking step, which is followed by isolation of specific protein-DNA complexes and subsequent PCR testing, to analyze DNA-protein interactions. Poly(ADP-ribosyl)ation, a posttranslational modification involved in diverse cellular functions like repair, replication, transcription, and cell death regulation, is most prominent after DNA damage. Poly(ADP-ribose)polymerase-1 is activated upon binding to DNA strand-breaks and coordinates repair by recruitment or displacement of proteins. Several proteins involved in different nuclear pathways are directly modified or contain poly(ADP-ribose)-interaction motifs. Thus, poly(ADP-ribose) regulates chromatin composition. In immunofluorescence experiments, we noticed artificial polymer-formation after formaldehyde-fixation of undamaged cells. Therefore, we analyzed if the formaldehyde applied during ChIP also induces poly(ADP-ribosyl)ation and its impact on chromatin composition. We observed massive polymer-formation in three different ChIP-protocols tested independent on the cell line. This was due to induction of DNA damage signaling as monitored by γH2AX formation. To abrogate poly(ADP-ribose) synthesis, we inhibited this enzymatic reaction either pharmacologically or by increased formaldehyde concentration. Both approaches changed ChIP-efficiency. Additionally, we detected specific differences in promoter-occupancy of tested transcription factors as well as the in the presence of histone H1 at the respective sites. In summary, we show here that standard ChIP is flawed by artificial formation of poly(ADP-ribose) and suppression of this enzymatic activity improves ChIP-efficiency in general. Also, we detected specific changes in promoter-occupancy dependent on poly(ADP-ribose). By preventing polymer synthesis with the proposed modifications in standard ChIP protocols it is now possible to analyze the natural chromatin-composition.

Effect of glutaraldehyde fixation on bacterial cells observed by atomic force microscopy

Atomic force microscopy (AFM) is a promising microscopy technique that can provide high-resolution images of bacterial cells without fixation. Three species of bacteria, Xanthomonas campestris, Pseudomonas syringae, and Bacillus subtilis, were used in this study. AFM images were obtained from unfixed and glutaraldehyde-fixed cells, and cell height was measured. The mean height of bacterial cells prepared by fixation was higher than that of those prepared by nonfixation. However, the height changes were different between Gram-negative and Gram-positive bacteria: the mean height of two fixed Gram-negative bacteria, X. campestris and P. syringae, increased by 112.31 and 84.08%, respectively, whereas Gram-positive bacterium, B. subtilis, increased only by 38.79%. The results above indicated that glutaraldehyde fixation could affect the measured height of cells imaged by AFM; further more, the effect of glutaraldehyde fixation on the measured height of Gram-negative bacterial cells imaged by AFM seemed much more than on that of Gram-positive bacterial cells.

Genome-wide comparison of paired fresh frozen and formalin-fixed paraffin-embedded gliomas by custom BAC and oligonucleotide array comparative genomic hybridization: facilitating analysis of archival gliomas

Array comparative genomic hybridization (aCGH) is a powerful tool for detecting DNA copy number alterations (CNA). Because diffuse malignant gliomas are often sampled by small biopsies, formalin-fixed paraffin-embedded (FFPE) blocks are often the only tissue available for genetic analysis; FFPE tissues are also needed to study the intratumoral heterogeneity that characterizes these neoplasms. In this paper, we present a combination of evaluations and technical advances that provide strong support for the ready use of oligonucleotide aCGH on FFPE diffuse gliomas. We first compared aCGH using bacterial artificial chromosome (BAC) arrays in 45 paired frozen and FFPE gliomas, and demonstrate a high concordance rate between FFPE and frozen DNA in an individual clone-level analysis of sensitivity and specificity, assuring that under certain array conditions, frozen and FFPE DNA can perform nearly identically. However, because oligonucleotide arrays offer advantages to BAC arrays in genomic coverage and practical availability, we next developed a method of labeling DNA from FFPE tissue that allows efficient hybridization to oligonucleotide arrays. To demonstrate utility in FFPE tissues, we applied this approach to biphasic anaplastic oligoastrocytomas and demonstrate CNA differences between DNA obtained from the two components. Therefore, BAC and oligonucleotide aCGH can be sensitive and specific tools for detecting CNAs in FFPE DNA, and novel labeling techniques enable the routine use of oligonucleotide arrays for FFPE DNA. In combination, these advances should facilitate genome-wide analysis of rare, small and/or histologically heterogeneous gliomas from FFPE tissues.

[The effect of treatment of temporalis muscle fascia grafts with formaldehyde on the success rates of tympanoplasty]

OBJECTIVES

This study aims to investigate the effect of formaldehyde treatment of temporalis muscle fascia grafts used during tympanoplasty on the postoperative success rates.

PATIENTS AND METHODS

Fifty-four patients who underwent tympanoplasty between January 2006 and January 2007 in the Department of Otolaryngology, Medicine Faculty of Uludağ University and who were under regular follow-up were included in this prospectively planned study and divided into two groups: the study group (n=24) and the control group (n=30). Temporal muscle fascia grafts were used in all patients. The grafts were treated with formaldehyde in the study group. All the controls of the patients were performed by otomicroscopy. Audiometric tests were performed at the 6th month controls.

RESULTS

It was found out that perforation was permanently repaired in 79.2% of the study group and in 73.3% of the control group (p>0.05). We obtained an evident improvement in the average airway bone gap in both groups. We could not detect any statistical significance in the comparison of the operation duration between the groups although the operation duration in the study group was shorter (the study group: 735 seconds, the control group: 775 seconds).

CONCLUSION

The formaldehyde treatment of the temporalis muscle fascial graft used in tympanoplasty was not superior in closing perforation and operation length compared to its direct dry use. However, we concluded that the graft could be more easily manipulated during the operation.

[Effect of formaldehyde in low concentrations on the proliferation and organization of the cytoskeleton of cultured cells]

3-4% (1.07-1.42 M) formaldehyde is one of the most popular and well-known organs, tissues and cells fixer. In this manuscript we have shown that formaldehyde in concentrations of up to 60 microM (0.0002%) does not have any negative effect on the viability of cell lines A431, HEK293 and primary rat fibroblasts, but it is also increases the proliferative activity of A431. The influence on A431 cells might be explained by the activation of epidermal growth factor receptors as a result of their interaction with formaldehyde.

Influence of formalin fixation on the biomechanical properties of human diaphyseal bone

Owing to the lack of fresh human bones, formalin-fixed specimens are frequently used in biomechanical testing. However, formalin fixation is assumed to affect the biomechanical properties of bone. The aim of this study was to compare axial and torsional stiffness and bone mineral density in fresh and embalmed human bones. The subtrochanteric regions of 12 pairs of fresh human femora were randomised into two groups for paired comparison. After bone mineral density measurement, one group was preserved in 4% formalin. After 6 weeks, bone mineral density was remeasured and each specimen underwent axial and torsional loading. The formalin group showed significant higher stiffness values for torsional and axial loads than the fresh group. Axial stiffness increased by 14.1%, whereas torsional stiffness increased by 14.3%. These differences were not reflected in bone mineral density values. Formalin fixation significantly influences the stiffness of human cadaveric bones. Fresh bones represent the in vivo conditions better than formalin fixed bones.

[Role of the surgical pathology laboratory in the pre-analytical approach of molecular biology techniques]

The advent of the targeted cancer therapies administered to patients, according to the results of molecular biology techniques (in particular, in situ hybridization, "polymerase chain reaction" amplification and sequencing), has modified the practice of the surgical pathology laboratories. The necessity to answer to the needs of physicians for optimizing the medical care for patients who develop cancer has led to a policy of national debate, spurred by the National Institute of Cancer (INCa), in order to implement new procedures in the pathology laboratories. Thus, in addition to the structuring of molecular biology platforms and their labeling by INCa, the upstream control of the steps present between resection of tumor samples and molecular analysis has proved to be crucial. Indeed, the quality of this upstream time, called "pre-analytical" phase, determines the reliability of the molecular biology results and therefore the therapeutic strategy. We describe here the main steps to be checked in the pre-analytical phase. The optimization of this pre-analytical phase within the surgical pathology laboratory aims to reduce or render insignificant the risk of errors of molecular biology tests. These errors can indeed lead to false negative or false positive results whose therapeutic consequences can be particularly harmful to patients with cancer.

Comparison of red blood cell membrane microstructure after different physicochemical influences: atomic force microscope research

PURPOSE

After the influence of different actions on the blood, the erythrocytes may change their macrostructure. At the same time, the microstructure of cell membrane will be changed as well. This study provides the results of comparison of red blood cell membrane microstructure after they have been affected by different factors.

MATERIALS AND METHODS

Images and spatial profiles of the cell surface were obtained by atomic force microscope. It was proposed to use spatial Fourier transform to decompose the initial complex profile into series of simple ones. This made it possible to compare surface parameters after exposure of red blood cells to different external actions.

RESULTS

Quantitative differences between membrane profile harmonic composition parameters (amplitude and spatial period) after physical impact (impulse electrical field, osmotic swelling) and after chemical impact (the fixing fluid glutaraldehyde and the drug Esmeron) were experimentally confirmed.

CONCLUSIONS

Such experimental and theoretical approach may lay down the foundations of mechanisms of different factors' effect on red blood cells both in research and in clinics.

Immunocytochemical detection of tissue antigens after prolonged storage of specimens in methylsalicylate

The aim of the present work was to verify the possibility of detecting various tissue antigens using standard immunocytochemical methods in paraffin sections of specimens stored in methylsalicylate for two years and longer before embedding in paraffin. Using the immunocytochemical reaction for the intermediate filament proteins nestin, vimentin, and GFAP, the neuron marker NeuN, neuron-specific enolase, and doublecortin as examples, these experiments showed that prolonged storage of dehydrated specimens in methylsalicylate does not prevent detection of antigens using immunocytochemical reactions.

[Application of polyguanidine solution for fixation of biological and anatomical specimens]

A new method for fixation of biological material is described, and its effectiveness is compared to that one of formalin fixation. As an embalming agent, polyhexamethylenguanidine (PHMG) hydrochloride was used. Using the proposed method of fixation, the anatomical and histological preparations of human organs and of chick embryos at developmental 12 days, were produced. The anatomical preparations obtained show the appearance, similar to that of the recently removed organs. Histological preparations were free from significant distortions of the microscopic characteristics of the specimens, which are typical to the material fixed with formalin. The results of the study suggest the possibility of PHMG application in the morphological studies.

In vitroantioxidant activities of antioxidant-enriched toothpastes

Several forms of periodontal diseases (PD) are often associated with modified phagocytosing leukocytes and contemporary free radical production. Host antioxidant defenses could benefit from toothpastes used as adjuncts to counteract plaque-associated bacteria. The aim of the present study was to determine possible antioxidant activity (AA) of 12 differently antioxidant-enriched toothpastes, regardless of their efficacy as antimicrobial agents. Toothpastes were enriched alternatively with sodium ascorbyl phosphate, alpha-tocopherol acetate, pycnogenol, allantoin and methyl salycilate or a mixture of these. AA was tested in a cell-free system with a ABTS-decolorization assay improved by means of a flow injection analysis device. Comet assay, using NCTC 2544 keratinocytes, was performed to test if it was possible to identify any protection against in vitro DNA fragmentation provoked by a challenge with H(2)O(2) in cultures pre-incubated with toothpaste extracts. Only toothpastes containing sodium ascorbyl phosphate displayed clear AA with I(50) values ranging between 50 and 80 mg of toothpaste/ml water. COMET analysis of cells challenged with H(2)O(2) in presence of toothpaste extracts revealed a limited protection exerted by sodium ascorbyl phosphate. The results described herein indicate that toothpastes containing sodium ascorbyl phosphate possess AA. All the data were obtained in systems in vitro and the demonstration of in vivo AA is desirable. These findings could be useful in the treatment and maintenance of some forms of PD and should be considered when arranging new toothpaste formulations.

Chromosome shattering: a mitotic catastrophe due to chromosome condensation failure

Chromosome shattering has been described as a special form of mitotic catastrophe, which occurs in cells with unrepaired DNA damage. The shattered chromosome phenotype was detected after application of a methanol/acetic acid (MAA) fixation protocol routinely used for the preparation of metaphase spreads. The corresponding phenotype in the living cell and the mechanism leading to this mitotic catastrophe have remained speculative so far. In the present study, we used V79 Chinese hamster cells, stably transfected with histone H2BmRFP for live-cell observations, and induced generalized chromosome shattering (GCS) by the synergistic effect of UV irradiation and caffeine posttreatment. We demonstrate that GCS can be derived from abnormal mitotic cells with a parachute-like chromatin configuration (PALCC) consisting of a bulky chromatin mass and extended chromatin fibers that tether centromeres at a remote, yet normally shaped spindle apparatus. This result hints at a chromosome condensation failure, yielding a "shattered" chromosome complement after MAA fixation. Live mitotic cells with PALCCs proceeded to interphase within a period similar to normal mitotic cells but did not divide. Instead they formed cells with highly abnormal nuclear configurations subject to apoptosis after several hours. We propose a factor depletion model where a limited pool of proteins is involved both in DNA repair and chromatin condensation. Chromosome condensation failure occurs when this pool becomes depleted.

Preliminary evidence that regular vinegar ingestion favorably influences hemoglobin A1c values in individuals with type 2 diabetes mellitus

This report examined whether daily acetic acid ingestion as vinegar, dill pickle, or commercial vinegar pill influenced hemoglobin A1c in diabetic patients. Hemoglobin A1c values fell 0.16% with vinegar use but rose 0.06% and 0.22% for pill and pickle use respectively (p=0.018). Hence, regular vinegar use modestly improved glycemic control.

Reduced antigenicity of formaldehyde-fixed arterial allografts and their potential clinical application

This study was performed to examine the antigenicity of formaldehyde-fixed arterial allografts and their potential clinical application for hemodialysis access. Human femoral arteries were fixed with formaldehyde. New Zealand white rabbits were immunized with antigens prepared from fixed or unfixed grafts followed by anti-serum collection. The antigenicity of fixed grafts was evaluated using double-diffusion in two dimensions. Seventy-six fixed allografts were transplanted into 50 patients with end-stage renal diseases as hemodialysis access and monitored for acute rejection, blood flow, and patency rates. Anti-HLA antibody was evaluated using a panel-reactive antibody (PRA) assay in 6 patients. Formaldehyde-fixed grafts demonstrated reduced antigenicity as determined using double-diffusion in two dimensions when compared with unfixed grafts. Histological evaluation of allografts demonstrated absence of cell-mediated acute rejection after transplantation. Allografts demonstrated satisfactory blood flow with primary and secondary patency rates at 1, 2, and 3 years after allotransplantation. Serum collected from 6 patients after transplantation (mean, 3.3 +/- 3.2 years) did not demonstrate increased anti-HLA antibody levels. The allograft intimal hyperplasia was characterized by proliferation of actin-expressing smooth muscle cells. This study demonstrated that formaldehyde fixation reduced the antigenicity of arterial allografts. Acute rejection was absent after allotransplantation. The lack of increased PRA levels after allotransplantation suggested that allo-sensitization is not induced by fixed allografts. The use of formaldehyde-fixed allografts as hemodialysis access demonstrated blood flow and patency rates. Intimal hyperplasia of allografts is characterized by proliferation of actin-expressing cells. Our results supported the clinical use of formaldehyde-fixed arterial allografts for hemodialysis access.

Preparative procedures markedly influence the appearance and structural integrity of protein storage vacuoles in soybean seeds

In legumes, vacuoles serve as the final depository for storage proteins. The protein storage vacuoles (PSVs) of soybean contain electron-transparent globoid regions in which phytic acid ( myo-inositol-1,2,3,4,5,6-hexakisphosphate) is sequestered. This paper reports the effect of preparative procedures on the appearance and ultrastructural integrity of PSVs in soybeans. Electron microscopy examination of both developing and mature soybean seeds that were postfixed with osmium tetroxide revealed PSVs that had a homogeneous appearance with very few globoid crystals dispersed in them. Numerous electron-dense lipid bodies were readily seen in these cells. Omission of osmium tetroxide strikingly altered the appearance of PSVs and aided the visualization of the location of the globoids in the PSVs. In contrast to the osmicated tissue, lipid bodies appeared as electron-transparent spheres. The choice of dehydration reagent or staining procedure had little influence on the appearance of the PSVs. The results of this study demonstrate the profound effect of osmium tetroxide on the appearance and structural integrity of PSVs in soybean.

Effect of modified Davidson's fixative on examined number of lymph nodes and TNM-stage in colon carcinoma

AIMS

We evaluated the effect of modified Davidson's fixative (mDF) on the number of lymph nodes examined and staging in patients with colon carcinoma.

METHODS

The results of two different fixation methods used in the pathological preparation of the resection specimens were analyzed. A traditional formalin preparation with manual dissection of all nodes was performed in 117 colon specimens between January 2003 and July 2004. After July 2004, the resected specimens of 125 patients was fixated in mDF. Differences in the retrieval and number of nodes and size of suspected nodal metastases were measured. All lymph nodes were stained with conventional H&E methods.

RESULTS

The median number of examined nodes increased from 5 (0-17) to 13 (0-35) nodes after the introduction of mDF (p<0.001). The type of resection and the T-stage influenced the number of retrieved nodes significantly. The percentage of node-positive cases increased from 30% to 41% (p=0.077) with mDF, the median size of the retrieved lymph nodes decreased from 9 mm before to 6 mm after mDF (p<0.001) and more micrometastases were found (6% vs. 16%, p=0.03).

CONCLUSIONS

With mDF technique more lymph nodes were retrieved in the resected colon specimens. Smaller nodes and more micrometastases were found, leading to more node positive patients.

Real-time polymerase chain reaction assays for rapid detection and quantification of Noctiluca scintillans zoospore

Application and availability of real-time polymerase chain reaction (PCR) assay to detect and quantify the Noctiluca scintillans zoospore were investigated seasonally. Specific primer set for N. scintillans 18S rDNA was designed and applied to real-time PCR assay using the serial dilutions of N. scintillans zoospores. The real-time PCR assays with Ns63F and Ns260R primers were applied to sea water samples collected weekly in Manazuru Port of Sagami Bay, Japan from April 2005 to June 2006. We developed effective DNA preparation steps for collecting the template DNA of N. scintillans zoospore: size fraction and filter concentration of the water samples, fixation with Lugol solution, cell lysis, and purification. This method is useful for the monitoring of the zoospores of N. scintillans, and can also be used for other small and physiologically fragile planktonic cell. Variation in the density of zoospore was successfully detected in the field samples. The peak density of N. scintillans zoospore was observed to occur just before or at the same time as the peak of the vegetative cells. Moreover, zoospores were detected in seawater even when the vegetative cells were not observed. The presence of zoospore was found all year round in the present study. In this regards, this information is essential for the study of the life cycle and seasonal variation of N. scintillans in the coastal waters.

The effect of paraformaldehyde fixation and PBS storage on the water content of the human lens

PURPOSE

Fixation and phosphate buffered saline (PBS) storage are frequently used before studies of the morphological, biochemical, and optical properties of the human lens begin. It is assumed that this does not alter the properties being examined. The present study was undertaken to determine the effects of fixation and PBS storage on the human lens wet weight.

METHODS

Human donor lenses were incubated in a buffered paraformaldehyde (PF) solution or in PBS and their wet weights were monitored for up to 44 and 13 days, respectively.

RESULTS

PF fixation resulted in a large decrease in wet weight, averaging 25%+/-2.3% at 30 days for 14 human donor lenses, aged 49-80 years. The loss was essentially complete by 21 days. Out of the 10 lenses, aged 52-71 years, which were incubated in PBS alone, six of them increased in weight by an average of 38% over 13 days and four ruptured within four days. Comparison of literature data for a fixed eight-year-old lens with those for an unfixed seven-year-old lens indicated that the decrease in wet weight was due mainly to a loss of water from the cortex, which resulted in virtual disappearance of the water/protein gradient and the formation of a plateau containing 58% water in over 90% of the lens.

CONCLUSIONS

Fixation substantially alters the amount and distribution of water in the human lens. Caution should be exercised when interpreting data on water and protein distributions as well as cell dimensions obtained with lenses which have been fixed. In addition, prolonged storage of a lens in PBS will result in substantial water uptake, which may affect measurements of their dimensions and optical properties.

Comparison of the fixative properties of five disinfectant solutions

Following a French circular published in 2001, the use of glutaraldehyde for the disinfection of reusable medical devices was abandoned in favour of non-fixative disinfectants such as peracetic-acid-based solutions. Data published regarding the fixative properties of alternative disinfectants remain contradictory. We compared the effect of repetitive treatments of polytetrafluoroethylene (PTFE) tubes, contaminated by a liquid medium inoculated with Pseudomonas aeruginosa, using five different disinfectant solutions: two peracetic acid solutions (with and without an activator), glutaraldehyde, ortho-phthaldehyde and succine dialdehyde. The results confirmed that repeated treatments of a PTFE tube with a 2% glutaraldehyde solution induce an important accumulation and/or fixation of protein, compared to peracetic-acid-based disinfectants, for which the accumulation and/or fixation of proteins remain low and vary from one formulation to another.

A protocol for isolation and visualization of yeast nuclei by scanning electron microscopy

This article describes a protocol that details methods for the isolation of yeast nuclei from budding yeast (Saccharomyces cerevisiae) and fission yeast (Schizosaccharomyces pombe), immunogold labelling of proteins, and visualization by Field Emission Scanning Electron Microscopy (FESEM). This involves the removal of the yeast cell wall and isolation of the nucleus from within, followed by subsequent processing for high resolution microscopy. The nuclear isolation step is performed by enzymatic treatment of yeast cells to rupture the cell wall and generate spheroplasts (cells that have partially lost their cell wall and their characteristic shape), followed by isolation of nuclei by centrifugation. This protocol has been optimized for the visualization of the yeast nuclear envelope (NE), nuclear pore complexes (NPCs), and associated cytoskeletal structures. Samples, once processed for FESEM, can be stored under vacuum for weeks, allowing considerable time for image acquisition.

Long term formalin preserved stool specimens for detection of intestinal parasites from school aged children in Tripoli, Libya

A total of 949 single stool samples were collected from school aged children (5-14 years old) in the city of Tripoli. The samples were preserved in 10% formalin and examined by routine microscopy using normal saline and Lugol's iodine preparations as well as the formol ethyl concentration method after a storage period of twelve months at room temperature. Of 949 samples examined 4.5% were positive. Giardia lamblia and Entamoeba coli were the only protozoan parasites identified with an infection rate of 3.2% & 1.3% respecttively. No helminthes were detected in any of the samples. About 14% of the children had intestinal yeast infection Candida albicans in their stool of which 0.63% was infected with intestinal parasites. No distortion or alteration of morphology was observed particularly in G. lamblia. Preservation in 10% formalin is a very productive means for the accurate identification of protozoan parasites.

Clinical studies of hemodialysis access through formaldehyde-fixed arterial allografts

Efficient hemodialysis requires establishing a permanent stable vascular access. Our study was designed to evaluate formaldehyde-fixed arterial allografts as hemodialysis access for end-stage renal disease. Various parameters were determined for 68 formaldehyde-fixed, cadaver-derived allografts transplanted into 43 hemodialysis patients. The sources of the allografts were determined to be free of cytomegalovirus, hepatitis B and hepatitis C, and HIV infections. These allografts were monitored for rejection, blood flow, patency rates, and complications. Overall, antigenicity of the allografts was reduced after formaldehyde fixation with no acute rejection. The mean access blood flow was 696+/-282 ml with reasonable primary and secondary patency rates even after 3 years. Allograft intimal hyperplasia, determined by immunohistochemistry, was evident as the proliferation of smooth muscle-like cells expressing actin but cells not expressing the endothelial markers von Willebrand factor or CD34. The incidence of thrombus formation was about 37% after allograft transplant with other limited complications of pseudoaneurysms and local infection. Our results support the clinical use of formaldehyde-fixed arterial allografts for hemodialysis access.

Size variation of trichospores of Harpella melusinae in larval black flies

Trichospores of Harpella melusinae in larval black flies from four streams in northwestern South Carolina were measured. The longest fresh trichospore was 242 microm, 38% longer than the reported maximum length of trichospores for this species. After staining with lactophenol cotton blue, trichospore length was significantly reduced by up to 24.4% in fresh larvae and up to 4.9% in fixed larvae. Mean trichospore length differed significantly between seasons and between sampling sites but did not differ significantly between middle and final instars. Trichospore length correlated significantly with host size. We suggest that taxonomic descriptions of trichomycetes should include measurements of fresh, fixed and stained trichospores.