Feasibility of MALDI-MSI-Based Proteomics Using Bouin-Fixed Pathology Samples: Untapping the Goldmine of Nephropathology Archives.

The application of innovative spatial proteomics techniques, such as those based upon matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) technology, has the potential to impact research in the field of nephropathology. Notwithstanding, the possibility to apply this technology in more routine diagnostic contexts remains limited by the alternative fixatives employed by this ultraspecialized diagnostic field, where most nephropathology laboratories worldwide use bouin-fixed paraffin-embedded (BFPE) samples. Here, the feasibility of performing MALDI-MSI on BFPE renal tissue is explored, evaluating variability within the trypsin-digested proteome as a result of different preanalytical conditions and comparing them with the more standardized formalin-fixed paraffin-embedded (FFPE) counterparts. A large proportion of the features (270, 68.9%) was detected in both BFPE and FFPE renal samples, demonstrating only limited variability in signal intensity (10.22-10.06%). Samples processed with either fixative were able to discriminate the principal parenchyma regions along with diverse renal substructures, such as glomeruli, tubules, and vessels. This was observed when performing an additional "stress test", showing comparable results in both BFPE and FFPE samples when the distribution of several amyloid fingerprint proteins was mapped. These results suggest the utility of BFPE tissue specimens in MSI-based nephropathology research, further widening their application in this field.

A High-Throughput PIXUL-Matrix-Based Toolbox to Profile Frozen and Formalin-Fixed Paraffin-Embedded Tissues Multiomes.

Large-scale high-dimensional multiomics studies are essential to unravel molecular complexity in health and disease. We developed an integrated system for tissue sampling (CryoGrid), analytes preparation (PIXUL), and downstream multiomic analysis in a 96-well plate format (Matrix), MultiomicsTracks96, which we used to interrogate matched frozen and formalin-fixed paraffin-embedded (FFPE) mouse organs. Using this system, we generated 8-dimensional omics data sets encompassing 4 molecular layers of intracellular organization: epigenome (H3K27Ac, H3K4m3, RNA polymerase II, and 5mC levels), transcriptome (messenger RNA levels), epitranscriptome (m6A levels), and proteome (protein levels) in brain, heart, kidney, and liver. There was a high correlation between data from matched frozen and FFPE organs. The Segway genome segmentation algorithm applied to epigenomic profiles confirmed known organ-specific superenhancers in both FFPE and frozen samples. Linear regression analysis showed that proteomic profiles, known to be poorly correlated with transcriptomic data, can be more accurately predicted by the full suite of multiomics data, compared with using epigenomic, transcriptomic, or epitranscriptomic measurements individually.

Quantitative intracellular retention of delivered RNAs through optimized cell fixation and immunostaining.

Detection of nucleic acids within subcellular compartments is key to understanding their function. Determining the intracellular distribution of nucleic acids requires quantitative retention and estimation of their association with different organelles by immunofluorescence microscopy. This is particularly important for the delivery of nucleic acid therapeutics, which depends on endocytic uptake and endosomal escape. However, the current protocols fail to preserve the majority of exogenously delivered nucleic acids in the cytoplasm. To solve this problem, by monitoring Cy5-labeled mRNA delivered to primary human adipocytes via lipid nanoparticles (LNP), we optimized cell fixation, permeabilization, and immunostaining of a number of organelle markers, achieving quantitative retention of mRNA and allowing visualization of levels that escape detection using conventional procedures. The optimized protocol proved effective on exogenously delivered siRNA, miRNA, as well as endogenous miRNA. Our protocol is compatible with RNA probes of single molecule fluorescence in situ hybridization (smFISH) and molecular beacon, thus demonstrating that it is broadly applicable to study a variety of nucleic acids in cultured cells.

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.

Optimization of PAS stain and similar Schiff's based methods for glycogen demonstration in liver tissue.

Demonstration of glycogen in tissue holds considerable diagnostic relevance across various pathological conditions, particularly in certain tumors. The histochemical staining of glycogen using methods utilizing Schiff's reagents is subject to influences arising from the type of fixative, fixation temperature, and oxidizing agents employed. This study aimed to assess diverse fixatives, fixation temperatures, and oxidizing agents, each with variable treatment durations, in conjunction with Schiff's reagent for optimal glycogen demonstration. Paraffin blocks derived from a rabbit's liver served as the experimental substrate, encompassing 340 paraffin sections subjected to different procedures. For tissues fixed at 4 °C, good staining outcomes, as determined by the periodic acid-Schiff (PAS) stain, were observed with 10% neutral buffered formalin (NBF), 80% alcohol, and Bouin's solution. Tissues fixed at room temperature (RT) demonstrated good PAS staining results with both 10% NBF and 80% alcohol. Notably, other oxidizing agents exhibited poor outcomes across all fixatives and fixation temperature, with two exceptions, as satisfactory staining results were obtained when using 5% chromic acid. Consequently, Both 10% NBF and 80% emerge as preferred fixatives of choice for glycogen demonstration when coupled with PAS stain. It is noteworthy that Bouin's solution could also provide good outcomes when fixation occurred at 4 °C.

Glyoxal-methyl-ethylene sulfonic acid fixative enhances the fixation of cytoskeletal structures for Förster resonance energy transfer measurements.

Förster resonance energy transfer (FRET) serves as a tool for measuring protein-protein interactions using various sensor molecules. The tension sensor module relies on FRET technology. In our study, this module was inserted within the actinin molecule to measure the surface tension of the cells. Given that the decay curve of FRET efficiency correlates with surface tension increase, precise and accurate efficiency measurement becomes crucial. Among the methods of FRET measurements, FRET efficiency remains the most accurate if sample fixation is successful. However, when cells were fixed with 4% paraformaldehyde (PFA), the actinin-FRET sensor diffused across the cytoplasm; this prompted us to explore fixation method enhancements. Glyoxal fixative has been reported to improve cytoskeletal morphologies compared to PFA. However, it was not known whether glyoxal fits FRET measurements. Glyoxal necessitates an acetic acid solution for fixation; however, acidic conditions could compromise fluorescence stability. We observed that the pH working range of glyoxal fixative aligns closely with MES (methyl-ethylene sulfonic acid) Good's buffer. Initially, we switched the acidic solution for MES buffer and optimized the fixation procedure for in vitro and in vivo FRET imaging. By comparing FRET measurements on hydrogels with known stiffness to tumor nodules in mouse lung, we estimated in vivo stiffness. The estimated stiffness of cancerous tissue was harder than the reported stiffness of smooth muscle. This discovery shed lights on how cancer cells perceive environmental stiffness during metastasis.

An optimized workflow for transcriptomic analysis from archival paraformaldehyde-fixed retinal tissues collected by laser capture microdissection.

RNA sequencing (RNA-seq) coupled with laser capture microdissection (LCM) is a powerful tool for transcriptomic analysis in unfixed fresh-frozen tissues. Fixation of ocular tissues for immunohistochemistry commonly involves the use of paraformaldehyde (PFA) followed by embedding in Optimal Cutting Temperature (OCT) medium for long-term cryopreservation. However, the quality of RNA derived from such archival PFA-fixed/OCT-embedded samples is often compromised, limiting its suitability for transcriptomic studies. In this study, we aimed to develop a methodology to extract high-quality RNA from PFA-fixed canine eyes by utilizing LCM to isolate retinal tissue. We demonstrate the efficacy of an optimized LCM and RNA purification protocol for transcriptomic profiling of PFA-fixed retinal specimens. We compared four pairs of canine retinal tissues, where one eye was subjected to PFA-fixation prior to OCT embedding, while the contralateral eye was embedded fresh frozen (FF) in OCT without fixation. Since the RNA obtained from PFA-fixed retinas were contaminated with genomic DNA, we employed two rounds of DNase I treatment to obtain RNA suitable for RNA-seq. Notably, the quality of sequencing reads and gene sets identified from both PFA-fixed and FF tissues were nearly identical. In summary, our study introduces an optimized workflow for transcriptomic profiling from PFA-fixed archival retina. This refined methodology paves the way for improved transcriptomic analysis of preserved ocular tissue, bridging the gap between optimal sample preservation and high-quality RNA data acquisition.

Impact of the quality of resected thyroid cancer tissue sample on next-generation sequencing testing.

Activating rearranged during transfection (RET) proto-oncogene alterations can be identified using next-generation sequencing (NGS) of tumor DNA/RNA. We assessed factors associated with NGS (Oncomine Dx Target Test [ODxTT]) success for resected thyroid cancer (TC) specimens, including sample age, processing conditions, and DNA/RNA quality. TC samples were from three Japanese hospitals, with sample age <1-<10 years, fixative 10%/15% neutralized buffered formalin (NBF), and fixation time ≤48 h/>48 h-≤72 h. NGS success rate was defined as the percentage of samples returning validated NGS results (RET fusion-positive/negative [RNA] or RET mutation-positive/negative [DNA], detected using ODxTT). DNA/RNA quality was assessed with indexes based on electrophoresis (DNA/RNA integrity number, DV200 ) and quantitative polymerase chain reaction (DNA/RNA integrity score [ddCq/ΔCq]). NGS success rate (N = 202) was 90%/93% (DNA/RNA) overall, 98%-100% (DNA and RNA) for samples <3 years old, and 91% (DNA and RNA) for samples ≥3-<5 years old fixed in 10% NBF for ≤48 h. Multivariate logistic regression analysis identified ddCq and ΔCq as significant predictors of DNA and RNA NGS success rates, respectively. Quality assessment of nucleic acid extracted from archival tissue samples is important for achieving high NGS success rates in clinical practice, especially for samples ≥3 years old.

Methods for Fixing Biofilms of Staphylococcus aureus and Salmonella enterica for Microscopic Examination.

Different methods for fixing biofilms of Staphylococcus aureus and Salmonella enterica for light and electron microscopy were compared. Paraformaldehyde fixation did not preserve biofilm integrity during dehydration; Ito-Karnovsky fixation revealed cell morphology, but did not preserve the matrix. Ruthenium red combined with aldehydes allowed the matrix to be preserved and visualized. An analysis of the ultrastructure of S. aureus and S. enterica cells in biofilms and suspensions at various fixations is presented. The ultrastructure of the biofilm matrix has been described.

Screening of voice disorders concerning anatomy teachers who use formaldehyde cadaveric parts in laboratory classes.

Voice disorders are common among teachers and, in particular, anatomy teachers are exposed to a potential enemy for dysphonia, irritating chemicals, that is, formaldehyde. We seek to verify the association between: (1) teaching time, (2) type of cadaveric conservation to which the teacher is exposed and (3) hours of exposure to cadaveric preservative related to the different categories of voice disorders screening (ITDV). The sample consisted of 111 teachers who answered to 02 data collection instruments: I - Sociodemographic Data; II - ITDV. Among participating teachers there were 71 male and 40 female, with an average age of 43 years and 11 months and an average teaching time of 16 years and 5 months. Association tests between teaching time and ITDV demonstrate a significant result in the relationship between voice failure and teaching time (p<0.05). All 111 teachers use their voices in laboratory classes and use cadaveric material. From those, 107 teachers are exposed to formaldehyde as cadaveric parts' conservative solution. There was a significant association (p<0.05) between voice failure and the type of cadaveric conservative solution but non-significant relationship (p>0.05) between ITDV and the time of exposure to formaldehyde preservative. Teachers' ITDV showed vocal signs and symptoms. In particular, voice loss due to time of teaching in anatomy, and voice failure, due to exposure to formaldehyde and combinations used in anatomical parts and cadavers, were significant.

Assessment of formalin preserved and fresh frozen quadriceps tendon graft-suture constructs for load to failure testing: a biomechanical cadaveric study.

PURPOSE: Fresh-frozen specimen availability and cost may be a barrier for initiation of biomechanical studies where soft tissue is used in a construct with other medical devices. The impact of soft tissue preservation method on the outcomes of biomechanical studies in the specific case of graft-suture constructs is relatively unexplored. This study aimed to observe peak loads and failure modes in biomechanical testing of fresh-frozen (FF) versus formalin embalmed (FE) quadriceps tendon (QT) graft-suture constructs for soft tissue fixation in ACLR and assess suitability of FE QT graft constructs for load-to-fail testing. METHODS: Twenty QT grafts were harvested from human cadaver specimens. Ten grafts came from fresh-frozen donors and 10 from embalmed donors. All grafts were prepared with the modified Prusik knot using a braided composite suture and subjected to tensile loading. Comparisons between the biomechanical properties of the graft-suture constructs were made with unpaired t tests with α = 0.05. RESULTS: FE and FF constructs displayed similar peak loads and failure modes. FF constructs had greater elongation after pre-tensioning than FE (7.3 vs. 5.5 mm, p = 0.02) and greater elongation after cyclic loading than FE constructs (17.5 vs. 10.5 mm, p = 0.01). Hysteresis was greater for FF constructs at the 50th, 100th, 150th, and 200th cycle (p = 0.02, p = 0.07, p < 0.001, p = 0.004, respectively). FE constructs were stiffer than fresh-frozen (103 vs. 84 N/mm, p < 0.001). CONCLUSION: FE constructs were significantly stiffer but displayed similar peak load and failure mode to FF which was reflective of the strength of the suture material. FE grafts can offer an alternative to FF grafts in graft-suture constructs for biomechanical studies where load at failure and knot security and strength is of main interest.

A Novel Tissue Preservation and Transport Solution as a Substitute for Formalin.

Formalin, a common laboratory fixative, is a type 1 carcinogen; a biohazard with risks, environmental, disposal, and legal costs; and a chemical modifier of protein epitopes in tissues. A less-toxic tissue preservation method is therefore badly needed. We have developed a novel tissue preservation medium, Amber, composed of low-potassium dextran glucose, 10% honey, and 1% coconut oil. This study investigates Amber as compared with formalin with respect to the following aspects: (1) histologic preservation, (2) epitope integrity with immunohistochemistry (IHC) and immunofluorescence (IF), and (3) integrity of tissue RNA. Rat and human lung, liver, kidney, and heart tissues were collected and stored for 24 hours at 4 °C in Amber or formalin. The tissues were evaluated with hematoxylin and eosin; IHC: thyroid transcription factor, muscle-specific actin, hepatocyte-specific antigen, and common acute lymphoblastic leukemia antigen; and IF: VE-cadherin, vimentin, and muscle-specific actin. RNA quality upon extraction was also assessed. Amber demonstrated superior and/or noninferior performance in rat and human tissue evaluation with respect to standard techniques of histology, IHC, IF, and extracted RNA quality. Amber maintains high-quality morphology without compromising the ability to perform IHC and nucleic acid extraction. As such, Amber could be a safer and superior substitute to formalin for clinical tissue preservation for contemporary pathological examination.

An optimized fixation method containing glyoxal and paraformaldehyde for imaging nuclear bodies.

The mammalian cell nucleus contains different types of membrane-less nuclear bodies (NBs) consisting of proteins and RNAs. Microscopic imaging has been widely applied to study the organization and structure of NBs. However, current fixation methods are not optimized for such imaging: When a fixation method is chosen to maximize the quality of the RNA fluorescence in situ hybridization (FISH), it often limits the labeling efficiency of proteins or affects the ultrastructure of NBs. Here, we report that addition of glyoxal (GO) into the classical paraformaldehyde (PFA) fixation step not only improves FISH signals for RNAs in NBs via augmented permeability of the fixed nucleus and enhanced accessibility of probes, but also largely preserves protein fluorescent signals during fixation and immunostaining. We also show that GO/PFA fixation enables the covisualization of different types of nuclear bodies with minimal impact on their ultrastructures under super-resolution microscopy.

Standardization of Grocott's methenamine (hexamine) silver method for glycogen demonstration in liver tissue.

Demonstration of glycogen can be done in different lesions and is considered diagnostically significant, mainly in some tumors. Glycogen staining is affected by the type of fixative, the temperature of fixation, and the staining technique.Grocott's methenamine (hexamine) silver technique quality was assessed after four different types of fixatives at two different temperatures [Bouin's solution, 10% neutral buffered formalin (NBF), 80% alcohol, and Rossman's solution at room temperature (RT) and 4 °C, for 24 h]. These variables were studied to optimize this technique for glycogen demonstration. Archived paraffin blocks were used in this study. They were prepared from one rabbit's liver, and 32 paraffin sections were prepared and stained with Grocott's methenamine (hexamine) silver technique. Eighty percent alcohol provided the highest staining quality scores at both RT and 4 °C in comparison with the other fixatives. We concluded that 80% alcohol at 4 °C seems to be the fixative of choice for glycogen with the Grocott's methenamine (hexamine) silver technique at the level of this study.

Tissue optimization strategies for high-quality ex vivo diffusion imaging.

Ex vivo diffusion imaging can be used to study healthy and pathological tissue microstructure in the rodent brain with high resolution, providing a link between in vivo MRI and ex vivo microscopy techniques. Major challenges for the successful acquisition of ex vivo diffusion imaging data however are changes in the relaxivity and diffusivity of brain tissue following perfusion fixation. In this study we address this question by examining the combined effects of tissue preparation factors that influence signal-to-noise ratio (SNR) and consequently image quality, including fixative concentration, contrast agent concentration and tissue rehydration time. We present an optimization strategy combining these factors to manipulate the T 1 and T 2 of fixed tissue and maximize SNR efficiency. We apply this strategy in the rat brain, for a diffusion-weighted spin echo protocol with TE = 27 ms on a 9.4 T scanner with a 39 mm volume coil and 660 mT/m 114 mm gradient insert. We used a reduced fixative concentration of 2% paraformaldehyde (PFA), rehydration time more than 20 days, 15 mM Gd-DTPA in perfusate and TR 250 ms. This resulted in a doubling of SNR and an increase in SNR per unit time of 135% in cortical grey matter and 88% in white matter compared with 4% PFA and no contrast agent. This improved SNR efficiency enabled the acquisition of excellent-quality high-resolution (78 µ m isotropic voxel size) diffusion data with b = 4000 s/mm 2 , 30 diffusion directions and a field of view of 40 × 13 × 18 mm3 in less than 4 days. It was also possible to achieve comparable data quality for a standard resolution (150 µ m) diffusion dataset in 2 1 4 h. In conclusion, the tissue optimization strategy presented here may be used to improve SNR, increase spatial resolution and/or allow faster acquisitions in preclinical ex vivo diffusion MRI experiments.

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.

Residual Humidity in Paraffin-Embedded Tissue Reduces Nucleic Acid Stability.

Molecular diagnostics in healthcare relies increasingly on genomic and transcriptomic methodologies and requires appropriate tissue specimens from which nucleic acids (NA) of sufficiently high quality can be obtained. Besides the duration of ischemia and fixation type, NA quality depends on a variety of other pre-analytical parameters, such as storage conditions and duration. It has been discussed that the improper dehydration of tissue during processing influences the quality of NAs and the shelf life of fixed tissue. Here, we report on establishing a method for determining the amount of residual water in fixed, paraffin-embedded tissue (fixed by neutral buffered formalin or a non-crosslinking fixative) and its correlation to the performance of NAs in quantitative real-time polymerase chain reaction (qRT-PCR) analyses. The amount of residual water depended primarily on the fixative type and the dehydration protocol and, to a lesser extent, on storage conditions and time. Moreover, we found that these parameters were associated with the qRT-PCR performance of extracted NAs. Besides the cross-linking of NAs and the modification of nucleobases by formalin, the hydrolysis of NAs by residual water was found to contribute to reduced qRT-PCR performance. The negative effects of residual water on NA stability are not only important for the design and interpretation of research but must also be taken into account in clinical diagnostics where the reanalysis of archived tissue from a primary tumor may be required (e.g., after disease recurrence). We conclude that improving the shelf life of fixed tissue requires meticulous dehydration and dry storage to minimize the degradative influence of residual water on NAs.

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.

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.

Glyoxal as an alternative fixative to formaldehyde in immunostaining and super-resolution microscopy.

Paraformaldehyde (PFA) is the most commonly used fixative for immunostaining of cells, but has been associated with various problems, ranging from loss of antigenicity to changes in morphology during fixation. We show here that the small dialdehyde glyoxal can successfully replace PFA Despite being less toxic than PFA, and, as most aldehydes, likely usable as a fixative, glyoxal has not yet been systematically tried in modern fluorescence microscopy. Here, we tested and optimized glyoxal fixation and surprisingly found it to be more efficient than PFA-based protocols. Glyoxal acted faster than PFA, cross-linked proteins more effectively, and improved the preservation of cellular morphology. We validated glyoxal fixation in multiple laboratories against different PFA-based protocols and confirmed that it enabled better immunostainings for a majority of the targets. Our data therefore support that glyoxal can be a valuable alternative to PFA for immunostaining.