Search

The choice of fixation method significantly impacts tissue morphology and visualization of gene expression and proteins after in situ hybridization chain reaction (HCR) or immunohistochemistry (IHC), respectively. In this study, we compared the effects of paraformaldehyde (PFA) and trichloroacetic acid (TCA) fixation techniques prior to HCR and IHC on chicken embryos. Our findings underscore the importance of optimizing fixation methods for accurate visualization and subsequent interpretation of HCR and IHC results, with implications for probe and antibody validation and tissue-specific protein localization studies. We found that TCA fixation resulted in larger and more circular nuclei and neural tubes compared to PFA fixation. Additionally, TCA fixation altered the subcellular fluorescence signal intensity of various proteins, including transcription factors, cytoskeletal proteins, and cadherins. Notably, TCA fixation revealed protein signals in tissues that may be inaccessible with PFA fixation. In contrast, TCA fixation proved ineffective for mRNA visualization. These results highlight the need for optimization of fixation protocols depending on the target and model system, emphasizing the importance of methodological considerations in biological analyses. [Display omitted] • TCA fixation alters cell and tissue morphology compared to PFA fixation. • PFA fixation is superior to TCA fixation prior to fluorescence in situ hybridization chain reaction (HCR). • Signals are detectable after immunohistochemistry (IHC) by fluorescence microscopy using both PFA and TCA fixation methods. • Tissue-specific fluorescence intensity of cadherin and microtubule protein signals differ between PFA and TCA-fixed embryos. [ABSTRACT FROM AUTHOR]

One‐pot synthesis of spirooxindoles bearing α‐metylene‐γ‐butyrolactone moiety has been carried out by the reaction of Morita–Baylis–Hillman (MBH) carbonates of isatins and paraformaldehyde in the presence of 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) in refluxing 1,2‐dichloroethane in moderate yields. The reaction proceeded via (i) the formation of resonance‐stabilized N‐ylide from DBU and the MBH carbonate of isatin, (ii) a selective γ‐attack of N‐ylide to formaldehyde, (iii) lactonization to liberate methoxide ion, (iv) addition of methoxide ion to the iminium part of DBU, (v) intramolecular hydride transfer via a six‐membered transition state, and finally (vi) elimination of DBU. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the potential of ozone as a sanitizer compared to commercial sanitizers for hatching eggs stored in hatching machines using different turning systems. The eggs (n = 120) were distributed in a completely randomized design using a factorial scheme (6x2) where the treatments were constituted by different sanitizers applied (non-treated eggs, Ozone 1.6 mg L-1, Ozone 3.2 mg L-1, Cyphenothrin, UVC, and paraformaldehyde) and two turning systems (vertical and horizontal) with 10 eggs each, with the egg considered as a replicate. Data collected were subjected to the Tukey test at 0.05. We observed a very similar performance in the incubation yield results of the hatching machines with different turning systems, where the hatching percentage of eggs stored in the hatching machine using vertical turning presented better (p < 0.05) results. Comparing ozone to other sanitizers, we observed that paraformaldehyde and UVC provided better (p < 0.05) hatching percentage. However, both ozone concentrations used also presented good hatching percentage results. Chicks from treated eggs, except those from eggs treated with the highest ozone concentration (3.2 mg L-1), were heavier (p < 0.05) at hatch. Chicks from eggs treated with the low concentration of ozone (1.6 mg L-1) presented, in several scenarios, higher (p < 0.05) weight at hatch than chicks from eggs treated with sanitizers commonly used, especially paraformaldehyde and UVC. Conclusively, ozone can be used as a sanitizer to treat eggs from older breeders, presenting potential to replace commonly used sanitizers stored in hatching machines using both vertical and horizontal turning systems.

The SARS-CoV-2 pandemic required the immediate need to transfer inactivated tissue from biosafety level (BSL)-3 to BSL-1 areas to enable downstream analytical methods. No validated SARS-CoV-2 inactivation protocols were available for either formaldehyde (FA)-fixed or glutaraldehyde (GA)-fixed tissues. Therefore, representative tissue from ferrets and hamsters was spiked with 2.2 × 106 tissue culture infectious dose 50% per ml (TCID50/ml) SARS-CoV-2 or were obtained from mice experimentally infected with SARS-CoV-2. SARS-CoV-2 inactivation was demonstrated with 4% FA or 5% GA at room temperature for 72 hours by a titer reduction of up to 103.8 TCID50/ml in different animal tissues with a maximum protein content of 100 µg/mg and a thickness of up to 10 mm for FA and 8 mm for GA. Our protocols can be easily adapted for validating the inactivation of other pathogens to allow for the transfer of biological samples from BSL-3 areas to BSL-1 laboratories. [ABSTRACT FROM AUTHOR]

Rift Valley fever phlebovirus (RVFV) is a highly pathogenic mosquito-borne virus with bioweapon potential due to its ability to be spread by aerosol transmission. Neurological symptoms are among the worst outcomes of infection, and understanding of pathogenesis mechanisms within the brain is limited. RVFV is classified as an overlap select agent by the CDC and USDA; therefore, experiments involving fully virulent strains of virus are tightly regulated. Here, we present two methods for inactivation of live virus within samples derived from mouse microglia cells using commercially available kits for the preparation of cells for flow cytometry and RNA extraction. Using the flow cytometry protocol, we demonstrate key differences in the response of primary murine microglia to infection with fully virulent versus attenuated RVFV. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the potential of ozone as a sanitizer compared to commercial sanitizers for hatching eggs stored in hatching machines using different turning systems. The eggs (n = 120) were distributed in a completely randomized design using a factorial scheme (6x2) where the treatments were constituted by different sanitizers applied (non-treated eggs, Ozone 1.6 mg L-1, Ozone 3.2 mg L-1, Cyphenothrin, UVC, and paraformaldehyde) and two turning systems (vertical and horizontal) with 10 eggs each, with the egg considered as a replicate. Data collected were subjected to the Tukey test at 0.05. We observed a very similar performance in the incubation yield results of the hatching machines with different turning systems, where the hatching percentage of eggs stored in the hatching machine using vertical turning presented better (p < 0.05) results. Comparing ozone to other sanitizers, we observed that paraformaldehyde and UVC provided better (p < 0.05) hatching percentage. However, both ozone concentrations used also presented good hatching percentage results. Chicks from treated eggs, except those from eggs treated with the highest ozone concentration (3.2 mg L-1), were heavier (p < 0.05) at hatch. Chicks from eggs treated with the low concentration of ozone (1.6 mg L-1) presented, in several scenarios, higher (p < 0.05) weight at hatch than chicks from eggs treated with sanitizers commonly used, especially paraformaldehyde and UVC. Conclusively, ozone can be used as a sanitizer to treat eggs from older breeders, presenting potential to replace commonly used sanitizers stored in hatching machines using both vertical and horizontal turning systems. [ABSTRACT FROM AUTHOR]

The currently employed red blood cell reagents have a short shelf life. Some hospitals with a small number of specimens will be unable to utilize them within the validity period, resulting in a substantial increase in the purchase price. Therefore, the method of developing long-term red blood cell reagents is a problem worthy of further study. In this experiment, the type and concentration of the red blood cell reagent treatment solution were evaluated based on the red blood cell antigen concentration 24 h after treatment. In addition, the qualified glutaraldehyde/paraformaldehyde reagent was stored for six months, and five red blood cell indices were measured every month. At the same time, the detection indices of treated red blood cell reagents and untreated red blood cell reagents were compared. It was discovered that treated red blood cells containing 0.005% GA and 0.05% PFA were more suitable for the preservation of red blood cells than other treated concentrations, and the preservation time could reach six months. The test tube method (n = 24) and microcolumn gel card (n = 35) were used to determine the accuracy of the treated blood cells containing 0.005% glutaraldehyde +0.05% paraformaldehyde, with an accuracy of 100%. This experiment resulted in the development of a novel reagent for treating red blood cells with glutaraldehyde/paraformaldehyde fixed solution that can effectively prolong its storage time by two to three times that of red blood cell reagents currently on the market. [ABSTRACT FROM AUTHOR]

The solvent-free reaction of 1,3,5-trioxane or paraldehyde with allyl alcohol under mild conditions afforded diallyloxymethane and 1,1-diallyloxyethane in up to 98% yields. The TsOH—CaCl2 (anhydrous) catalytic system used in the reaction allowed generation of HCl during the process. The use of paraformaldehyde instead of 1,3,5-trioxane increased the yield of diallyloxymethane up to 98%. [ABSTRACT FROM AUTHOR]

Integrating photocatalysis technology with peroxymonosulfate oxidation possesses huge potential for degrading stubborn pollutant. Herein, a porous ultra-thin carbon nitride with C-defect O-doping and advanced n - π* transition was customized by one-pot thermal-induced polymerization of molten urea assisted with paraformaldehyde. Via visible-light coupling peroxymonosulfate activation, the DCN-100 can completely photodegrade 2,4-dichlorophenol, and rate constant is 136.6 and 37.9 times that of CN and DCN-100 without peroxymonosulfate. The light-absorption of DCN-100 surpasses 550 nm, specific surface area rises from 45.03 to 98.58 m2/g, and charge behaviors are significantly improved. The effects of paraformaldehyde amount, PMS dosage, pH, 2,4-dichlorophenol concentration, different water-body, wavelength and recycling times on photodegradation performance were explored in detail. Via capture experiments, ESR, LC-MS, Fukui-function, TEXT toxicity assessment and DFT theoretical calculation, the main active substances, degradation pathway, intermediate toxicity and enhanced activity mechanism of DCN-100 were clarified. The research provides a cost-effective, high-efficiency and environmental-friendly photocatalysts to activate peroxymonosulfate for water remediating. [ABSTRACT FROM AUTHOR]

ABSTRACTObjective The currently employed red blood cell reagents have a short shelf life. Some hospitals with a small number of specimens will be unable to utilize them within the validity period, resulting in a substantial increase in the purchase price. Therefore, the method of developing long-term red blood cell reagents is a problem worthy of further study.Methods In this experiment, the type and concentration of the red blood cell reagent treatment solution were evaluated based on the red blood cell antigen concentration 24 h after treatment. In addition, the qualified glutaraldehyde/paraformaldehyde reagent was stored for six months, and five red blood cell indices were measured every month. At the same time, the detection indices of treated red blood cell reagents and untreated red blood cell reagents were compared.Results It was discovered that treated red blood cells containing 0.005% GA and 0.05% PFA were more suitable for the preservation of red blood cells than other treated concentrations, and the preservation time could reach six months. The test tube method (n = 24) and microcolumn gel card (n = 35) were used to determine the accuracy of the treated blood cells containing 0.005% glutaraldehyde +0.05% paraformaldehyde, with an accuracy of 100%.Conclusion This experiment resulted in the development of a novel reagent for treating red blood cells with glutaraldehyde/paraformaldehyde fixed solution that can effectively prolong its storage time by two to three times that of red blood cell reagents currently on the market.

A green and practical method for the electrochemical synthesis of tetrahydroimidazo[1,5‐a]quinoxalin‐4(5H)‐ones through the three‐component reaction of quinoxalin‐2(1H)‐ones, N‐arylglycines and paraformaldehyde was reported. In this strategy, EtOH played dual roles (eco‐friendly solvent and waste‐free pre‐catalyst) and the in situ generated ethoxide promoted triple sequential deprotonations. [ABSTRACT FROM AUTHOR]

A catalytic approach for the synthesis of N-[(alkylsulfanyl)methyl]- and N-[(arylsulfanyl)methyl]benzamides was developed via thiomethylation of 2-, 3- and 4-aminobenzamides with alkylthio- or arylthiomethanols. A moderate cytotoxic activity of 4-s[(heptylthio)methyl]aminobenzamide was established against a number of cell lines, with the most pronounced effect against the Jurkat leukemic T-cell line. [ABSTRACT FROM AUTHOR]

Rift Valley fever phlebovirus (RVFV) is a highly pathogenic mosquito-borne virus with bioweapon potential due to its ability to be spread by aerosol transmission. Neurological symptoms are among the worst outcomes of infection, and understanding of pathogenesis mechanisms within the brain is limited. RVFV is classified as an overlap select agent by the CDC and USDA; therefore, experiments involving fully virulent strains of virus are tightly regulated. Here, we present two methods for inactivation of live virus within samples derived from mouse microglia cells using commercially available kits for the preparation of cells for flow cytometry and RNA extraction. Using the flow cytometry protocol, we demonstrate key differences in the response of primary murine microglia to infection with fully virulent versus attenuated RVFV.

[Display omitted] • Design of a portable formaldehyde generation system with low gas consumption. • Dynamic generation with fast stabilisation rate. • Stability over a year for on and off generation of formaldehyde using a low-emission permeation tube. • Emission rate of formaldehyde from paraformaldehyde permeation depends only on temperature. Formaldehyde is a major indoor air pollutant. Accurate analysis of airborne formaldehyde is essential for effective monitoring and risk assessment. For many formaldehyde analysis techniques, the accuracy of the results depends on the calibration system. Existing formaldehyde calibration methods often face limitations, such as instability over time or limited concentration range. They also lack practicality for on-field calibration either because of bulkiness or because of high gas consumption. To address these challenges, a device using a paraformaldehyde permeation tube within a custom-built, temperature-controlled system was designed and evaluated. The device weighs less than 3 kg and operates using a nitrogen source. Its low gas consumption (30–100 mL min−1) enables the use of a portable gas cylinder of pure nitrogen (<2 kg) as gas supply. Formaldehyde concentrations ranging from 8.3 to 464 µg/m−3 were successfully generated, demonstrating the device's versatility. A custom-built high-emission permeation tube could generate concentrations from 5 940 to 49 471 µg/m−3 using the same system. Additionally, the emission rate is independent of the flow rate and follows Antoine's law with respect to temperature, enabling accurate prediction of concentration in various conditions over the evaluated range and beyond. Furthermore, the study confirms the long-term stability (1 year) of the low-emission paraformaldehyde permeation tube, with emission rates remaining mostly within ± 5 % of the average value for each temperature. The temperature-controlled permeation system approach enabled rapid stabilisation of formaldehyde generation at various concentrations and low flow rates, eliminating the need for additional dilution equipment and facilitating on-site instrument calibration at various gas concentrations. This reliable and efficient portable formaldehyde generator offers a valuable solution for field calibration, providing accurate and stable reference gas for diverse analytical needs. [ABSTRACT FROM AUTHOR]

ABSTRACT This study aimed to evaluate the effectiveness of ultraviolet light in reducing bacterial load of eggshells and the impact of experimental disinfection on hatching, embryo mortality, and time-borne distribution using broiler breeder hens of different ages (38, 42, and 48 weeks old). Fertile eggs were subjected to different exposure periods (5, 7, and 9 minutes) of UV light (UV-C) with a 254 nm wavelength. For controls, eggs disinfected with paraformaldehyde (5.3 g/m3) and eggs not disinfected (NC). After subjection to disinfection protocols, the eggs were placed into sterile plastic bags containing 20 mL of peptone saline solution (0.1% m:v) and massaged for 1 minute to release the bacterial load. Aliquots of this solution were incubated in specific medium for bacterial growth for 48 hours at 37ºC for subsequent CFU counts. To evaluate the effects of disinfection on production, eggs previously disinfected by UV-C (9 min) and paraformaldehyde and NC eggs were candled between incubation days 10 and 13 and at the end of the incubation period to assess embryonic mortality. Hatchability distribution was performed every 8 hours. The 9 minutes 254nm UV-C light exposure was able to disinfect viable eggs and matched the effectiveness of the paraformaldehyde technique.

Fixing cells with paraformaldehyde (PFA) is an essential step in numerous biological techniques as it is thought to preserve a snapshot of biomolecular transactions in living cells. Fixed-cell imaging techniques such as immunofluorescence have been widely used to detect liquid–liquid phase separation (LLPS) in vivo. Here, we compared images, before and after fixation, of cells expressing intrinsically disordered proteins that are able to undergo LLPS. Surprisingly, we found that PFA fixation can both enhance and diminish putative LLPS behaviors. For specific proteins, fixation can even cause their droplet-like puncta to artificially appear in cells that do not have any detectable puncta in the live condition. Fixing cells in the presence of glycine, a molecule that modulates fixation rates, can reverse the fixation effect from enhancing to diminishing LLPS appearance. We further established a kinetic model of fixation in the context of dynamic protein–protein interactions. Simulations based on the model suggest that protein localization in fixed cells depends on an intricate balance of protein–protein interaction dynamics, the overall rate of fixation, and notably, the difference between fixation rates of different proteins. Consistent with simulations, live-cell single-molecule imaging experiments showed that a fast overall rate of fixation relative to protein–protein interaction dynamics can minimize fixation artifacts. Our work reveals that PFA fixation changes the appearance of LLPS from living cells, presents a caveat in studying LLPS using fixation-based methods, and suggests a mechanism underlying the fixation artifact.

According to actual recommendations, the use of paraformaldehyde as a dental material should be significantly limited; however, it is still used in certain cases. Its use can cause delayed anaphylaxis, which can be life-threatening. We analyzed 157 patients admitted to an allergological clinic between 2017 and 2022 because of a hypersensitivity reaction after dental treatment. Paraformaldehyde was used in 24 of them. Positive specific IgE levels against paraformaldehyde were found in 12 patients, which constituted 50% of the whole group of patients who were treated with paraformaldehyde. Twelve patients had negative results of specific IgE against paraformaldehyde estimation (the PF group). Between the study and control groups, the anaphylactic reaction after paraformaldehyde application was analyzed from many aspects; the level of certainty of anaphylaxis according to Brighton criteria was significantly higher in the PF-positive group than in controls. None of the patients treated with paraformaldehyde as a dental material was informed by a dentist about this risk and symptoms of anaphylaxis. Patients who received paraformaldehyde during dental treatment should be informed of the possibility, symptoms, and treatment of an anaphylactic reaction, which might occur even 24 h after treatment. [ABSTRACT FROM AUTHOR]

Brain vascular staining is very important for understanding cerebrovascular pathologies. 4% paraformaldehyde is considered the gold standard fixation technique for immunohistochemistry and it revolutionized the examination of proteins in fixed tissues. However, this fixation technique produces inconsistent immunohistochemical staining results due to antigen masking. Here, we test a new fixation protocol using 3% glyoxal and demonstrate that this method improves the staining of the brain vasculature, pericytes, and tight junction proteins compared to 4% paraformaldehyde. Use of this new fixation technique will provide more detailed information about vascular protein expressions, their distributions, and colocalizations with other proteins at the molecular level in the brain vasculature. [ABSTRACT FROM AUTHOR]

The synthesis of homolimonenol by Prins condensation of limonene and paraformaldehyde over heterogeneous tin-based catalysts is reported for the first time. The tin supported MCM-41, SBA-15, and KIT-6 materials were prepared by incipient wetness impregnation method, using SnCl 2 ·2H 2 O as a tin precursor. The synthesized catalysts were characterized by N 2 -physisorption, X-ray diffraction (XRD), diffuse reflectance-infrared Fourier transform spectroscopy (DRIFTS), pyridine adsorption (Py-FTIR), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and chemical analysis. Sn4+ species were identified on the surface of the catalysts, and the materials showed mainly Lewis acid sites, which are responsible for the activity in the Prins reaction. Production of homolimonenol was confirmed by GC-MS and NMR analysis. Among the evaluated catalysts, the best conversion (26%), selectivity (90%) and TOF (12.7 h−1) were obtained over Sn-SBA-15, in the presence of ethyl acetate; Sn-SBA-15 catalyst was reused five times without loss of activity. The reaction was scaled up from 2 to 200 mL glass reactor with a local orange oil (93% wt/wt limonene) as a substrate, obtaining a 30% conversion of limonene and a 93% selectivity to homolimonenol. [Display omitted] • Novel application of tin-supported mesoporous catalysts for homolimonenol synthesis. • Sn4+ species on the surface were identified by XPS, acidity was mainly Lewis. • Homolimonenol from oxyfunctionalization of a sample of orange oil. • Sn-SBA-15 catalyst can be reused up to 5 times without loss of activity. [ABSTRACT FROM AUTHOR]

Here we report the efficient synthesis of a series of 1,3-dioxane derivatives from aromatic alkynes, paraformaldehyde, and a Lewis acid catalyzed reaction at room temperature. This reaction is metal-free and atom-economic. Single crystals of two typical 1,3-dioxane derivatives are obtained. A mechanism that the reaction proceeds through a six- or eight-membered ring intermediate is proposed. [ABSTRACT FROM AUTHOR]

The condensation/heterocyclization of 2-aminoethanol with formaldehyde and various alcohols afforded 3-(organyloxymethyl)-1,3-oxazolidines. Their yields depended on the nature of the hydroxy compound and increased in parallel with its size. 3,3′-Methylenebis(1,3-oxazolidine) was formed as by-product; it was also synthesized independently by the condensation of 2-aminoethanol with formaldehyde at a ratio of 2:3. Physico-chemical characteristics and 13C NMR spectra of the synthesized compounds are given. NMR signals were assigned using 13C–{1H} heteronuclear double-resonance technique. [ABSTRACT FROM AUTHOR]

In this study, a phosphorous‐containing benzoxazine was synthesized using a bio‐based primary amine, vanillin diamine true sample 2 (VDTS2, IUPAC name: 4‐(([3‐aminopropyl] imino) methyl)‐2‐methoxyphenyl(4‐(([3‐aminopropyl] imino) methyl)‐2‐methoxyphenyl) phenylphosphonate), paraformaldehyde and vanillin and tested for its use as a flame‐retardant. The molecular structure of the synthesized benzoxazines was characterized by FTIR spectroscopy and 1H NMR spectroscopy. Polybenzoxazine was obtained through the ring‐opening polymerization of the benzoxazine monomer, and the formation of the same was confirmed through FTIR spectroscopy. The polymerization mechanism of the benzoxazine was investigated using thermogravimetric analysis (TGA). The thermal properties of the benzoxazine were studied using differential scanning calorimetry and TGA. The flame‐retardant properties of the polybenzoxazine films obtained were investigated by the LOI. Due to the highly brittle nature of the polybenzoxazine, the synthesized polybenzoxazine was further crushed and incorporated into an epoxy system to investigate its use as a flame‐retardant additive. The thermal property and flame‐retardant property of the epoxy films were then studied. The flame‐retardant and thermal stability test results of the epoxy‐pbz films showed that the epoxy‐pbz films showed improved thermal stability and achieved a UL‐94 V‐0 rating and an LOI of 28% at 15% by weight of the polybenzoxazine concentration. SEM analysis was also conducted to study the surface morphology of the polybenzoxazine and epoxy‐pbz films pre and post the flame test. FTIR analysis was carried out to study the flame retardant mechanism of the polybenzoxazine and the epoxy‐pbz film. The respective films' mechanical properties were also investigated to study the film‐forming capability of the films. [ABSTRACT FROM AUTHOR]

Background. Complete relief of pain due to irreversible pulpitis is challenging to obtain with analgesic medications. The high incidence of an inferior alveolar nerve block (IANB) failure makes it difficult for practitioners to perform endodontic treatment without implementing other anesthetic techniques, especially mandibular molars. The aim of this study was to compare efficacies of two different quantities of paraformaldehyde based pulpal medicaments to relieve the pain and control hyperemic pulp post-failure of IANB and supplementary technique in patients experiencing this symptomatic irreversible pulpitis in the permanent mandibular tooth. Method. Eighty-two participants with severe pain pre-operatively (Heft Parker Visual Analogue Scale, VAS > 114 mm) were enrolled, and pain responses were recorded at different time intervals using the Heft Parker visual analogue scale. To the patients experiencing pain even after the administration of the standard IANB and supplemental intraligamentary injection, one of the two paraformaldehyde based pulpal medicaments was placed in the pulp chamber and sealed. Participants were recalled after 24-48 h (second visit) to assess pain and bleeding reduction. Results. Results showed a significant decrease in pain severity and bleeding score post medicament placement (p<:05). Hence judicious use within a recommended period, pulpal medicaments can be considered safe. Conclusion. Paraformaldehyde based pulpal medicament can be used as an alternative to manage pain in patients having severe irreversible pulpitis and hyperalgesia. [ABSTRACT FROM AUTHOR]

Introduction Paraformaldehyde has been used in endodontics when effective anaesthesia could not be achieved. However, this agent has many adverse effects including gingival, bone necrosis, osteomyelitis and allergy on account of systemic exposure. Therefore, the use of pastes containing paraformaldehyde should be avoided in contemporary dental practice. Objective The aim of this case report was to present the application of platelet-rich fibrin(PRF) in combination with a coronally advanced flap in the treatment of gingival and bone necrosis associated with paraformaldehyde containing devitalizing paste toxicity. PRF is an autogenous resorbable membrane composed of platelets, cytokines, leukocytes and growth factors. Results and conclusions Four weeks following burgery, the wound was completely healed with epithelial cells covering the interdental crater. On the basis of literature and of the present case, it can be stated that the use of PRF significantly reduces postoperative pain and promotes tissue healing.

Background Complete relief of pain due to irreversible pulpitis is challenging to obtain with analgesic medications. The high incidence of an inferior alveolar nerve block (IANB) failure makes it difficult for practitioners to perform endodontic treatment without implementing other anesthetic techniques, especially mandibular molars. The aim of this study was to compare efficacies of two different quantities of paraformaldehyde based pulpal medicaments to relieve the pain and control hyperemic pulp post-failure of IANB and supplementary technique in patients experiencing this symptomatic irreversible pulpitis in the permanent mandibular tooth. Method Eighty-two participants with severe pain pre-operatively (Heft Parker Visual Analogue Scale, VAS > 114 mm) were enrolled, and pain responses were recorded at different time intervals using the Heft Parker visual analogue scale. To the patients experiencing pain even after the administration of the standard IANB and supplemental intraligamentary injection, one of the two paraformaldehyde based pulpal medicaments was placed in the pulp chamber and sealed. Participants were recalled after 24–48 h (second visit) to assess pain and bleeding reduction. Results Results showed a significant decrease in pain severity and bleeding score post medicament placement (p

Abstract Background Collagen cross-linking of the sclera is a promising approach to strengthen scleral rigidity and thus to inhibit eye growth in progressive myopia. Additionally, cross-linking might inhibit degrading processes in idiopathic melting or in ocular inflammatory diseases of the sclera. Different cross-linking treatments were tested to increase resistance to enzymatic degradation of the rabbit sclera. Methods Scleral patches from rabbit eyes were cross-linked using paraformaldehyde, glutaraldehyde or riboflavin combined with UV-A-light or with blue light. The patches were incubated with collagenase I (MMP1) for various durations up to 24 h to elucidate differences in scleral resistance to enzymatic degradation. Degraded protein components in the supernatant were detected and quantified using measurements of Fluoraldehyde o-Phthaldialdehyde (OPA) fluorescence. Results All cross-linking methods reduced the enzymatic degradation of rabbit scleral tissue by MMP1. Incubation with glutaraldehyde (1%) and paraformaldehyde (4%) caused nearly a complete inhibition of enzymatic degradation (down to 7% ± 2.8 of digested protein compared to control). Cross-linking with riboflavin/UV-A-light reduced the degradation by MMP1 to 62% ± 12.7 after 24 h. Cross-linking with riboflavin/blue light reduced the degradation by MMP1 to 77% ± 13.5 after 24 h. No significant differences could be detected comparing different light intensities, light exposure times or riboflavin concentrations. Conclusions The application of all cross-linking methods increased the resistance of rabbit scleral tissue to MMP1-degradation. Especially, gentle cross-linking with riboflavin and UV-A or blue light might be a clinical approach in future.

BackgroundCharacterising the correlates of HIV persistence improves understanding of disease pathogenesis and guides the design of curative strategies. This study investigated factors associated with integrated HIV-1 DNA load during consistently suppressive first-line antiretroviral therapy (ART).MethodTotal, integrated, and 2-long terminal repeats (LTR) circular HIV-1 DNA, residual plasma HIV-1 RNA, T-cell activation markers, and soluble CD14 (sCD14) were measured in peripheral blood of 50 patients that had received 1-14 years of efavirenz-based or nevirapine-based therapy.ResultsIntegrated HIV-1 DNA load (per 10(6) peripheral blood mononuclear cells) was median 1.9 log10 copies (interquartile range 1.7-2.2) and showed a mean difference of 0.2 log10 copies per 10 years of suppressive ART (95% confidence interval - 0.2, 0.6; p = 0.28). It was positively correlated with total HIV-1 DNA load and frequency of CD8(+)HLA-DR/DP/DQ(+) cells, and was also higher in subjects with higher sCD14 levels, but showed no correlation with levels of 2-LTR circular HIV-1 DNA and residual plasma HIV-1 RNA, or the frequency of CD4(+)CD38(+) and CD8(+)CD38(+) cells. Adjusting for pre-ART viral load, duration of suppressive ART, CD4 cell counts, residual plasma HIV-1 RNA levels, and sCD14 levels, integrated HIV-1 DNA load was mean 0.5 log10 copies higher for each 50% higher frequency of CD8(+)HLA-DR/DP/DQ(+) cells (95% confidence interval 0.2, 0.9; p = 0.01).ConclusionsThe observed positive association between integrated HIV-1 DNA load and frequency of CD8(+)DR/DP/DQ(+) cells indicates that a close correlation between HIV persistence and immune activation continues during consistently suppressive therapy. The inducers of the distinct activation profile warrant further investigation.

Protocols for characterizing cellular phenotypes commonly use chemical fixatives to preserve anatomical features, mechanically stabilize tissue, and stop physiological responses. Formaldehyde, diluted in either phosphate-buffered saline or phosphate buffer, has been widely used in studies of neurons, especially in conjunction with dyes and antibodies. However, previous studies have found that these fixatives induce the formation of bead-like varicosities in the dendrites and axons of brain and spinal cord neurons. We report here that these formaldehyde formulations can induce bead formation in the dendrites and axons of adult rat and rabbit retinal ganglion cells, and that retinal ganglion cells differ from hippocampal, cortical, cerebellar, and spinal cord neurons in that bead formation is not blocked by glutamate receptor antagonists, a voltage-gated Na(+) channel toxin, extracellular Ca(2+) ion exclusion, or temperature shifts. Moreover, we describe a modification of formaldehyde-based fixatives that prevents bead formation in retinal ganglion cells visualized by green fluorescent protein expression and by immunohistochemistry.

• Measured susceptibility of mouse tissues with vibrating sample magnetometer. • Determined effect of chemical fixation on the magnetic properties of the tissues. • Serve as reference for MRI studies exploiting magnetic susceptibility contrast. Several magnetic resonance imaging (MRI) techniques exploit the difference in magnetic susceptibilities between tissues, but systematic measurements of tissue susceptibility are lacking. Furthermore, there is the question as to whether chemical fixation that is used for ex vivo MRI studies, affects the magnetic properties of the tissue. Here, we determined the magnetic susceptibility and water content of fresh and chemically fixed mouse tissue. Mass susceptibility of brain, heart, liver and skeletal muscle samples were determined on a vibrating sample magnetometer at room temperature. Measurements at 50, 125, 200 and 295 K were performed to assess the temperature dependence of susceptibility. Moreover, we measured water content of fresh and fixed samples. All samples show mass susceptibilities between −0.068 and −1.929 × 10−8 m3/kg, compared to −9.338 × 10−9 m3/kg of double distilled water. Heart tissue has a more diamagnetic susceptibility than the other tissues. Compared to fresh tissue, fixed tissue has a less diamagnetic susceptibility. Fixed tissue was not different in water content to fresh tissue and showed no consistent dependence of susceptibility with temperature, whereas fresh tissue shows a decrease to at least 125 K, indicative of a paramagnetic component. Biological tissues are diamagnetic in comparison to water, where the heart is more diamagnetic than the other tissues, with paramagnetic contributions. Fixation rendered tissue less diamagnetic compared to fresh tissue. Our measurements revealed differences in tissue susceptibility between VSM and QSM , inviting more research to compare susceptibility-based MRI methods with physical measurements of tissue susceptibility. [ABSTRACT FROM AUTHOR]

The first applying SrTiO 3 semiconductor as a photocatalyst in organic synthesis and using NPh 3 as a redox catalyst in photocatalysis was reported. With SrTiO 3 as the heterogeneous photocatalyst, NPh 3 as the homogeneous redox catalyst, H-bond as the promoter, paraformaldehyde as the cheap and atom economic methylene source, various 1,2,3,9b-tetrahydrobenzo[ d ]imidazo[1,5- b ]isothiazole 5,5-dioxides can be efficiently synthesized through the visible-light-induced cascade decarboxylative coupling/annulation reaction. [Display omitted] • Commercial SrTiO 3 semiconductor was firstly used for photocatalytic organic synthesis. • NPh 3 was firstly used as a redox catalyst in semiconductor photocatalysis. • Paraformaldehyde was used as the cheap and atom economic methylene source. • SrTiO 3 exhibits excellent photocatalytic activity for at least five catalytic cycles. The first applying SrTiO 3 semiconductor as a photocatalyst in organic synthesis and using NPh 3 as a redox catalyst in photocatalysis was reported. With SrTiO 3 as the heterogeneous photocatalyst, NPh 3 as the homogeneous redox catalyst, H-bond as the promoter, paraformaldehyde as the cheap and atom economic methylene source, various 1,2,3,9b-tetrahydrobenzo[ d ]imidazo[1,5- b ]isothiazole 5,5-dioxides can be efficiently synthesized through the visible-light-induced cascade decarboxylative coupling/annulation reaction. [ABSTRACT FROM AUTHOR]

Many of medicaments used historically in root canal treatment have been shown to be cytotoxic. Paraformaldehid agents (such as Toxavit and Depulpin) are used to devitalize inflamed pulp when local anesthesia is ineffective. The misuse of pulp devitalizing agents may cause damage to gingiva and alveolar bone. This case report demonstrates complications arising after application of paraformaldehyde containing paste, necrosis of the gingiva and alveolar cortical bone, which resulted in great loss of supporting bone. Surgical intervention was required wherein necrotic bone was removed and bone defect was filled with xenograft of bovine origin. After three months endodontic treatment was performed. After the treatment, the patient's complaints were resolved. The use of paraformaldehyde-based agents during endodontic therapy requires special caution.

[Display omitted] • Colombian sodium silicate is a promising silicon source to synthesize MCM-41. • Two Sn incorporation methods were tested in catalyst synthesis. • Sn/MCM-41 with Na 2 SiO 3 is highly active (TOF =476 h−1) to nopol synthesis. • An alternative low cost paraformaldehyde was effectively used. • Paraformaldehyde polymerization degree affect activity of nopol synthesis. Colombian sodium silicate was used as silicon source in the synthesis of MCM-41 with several surfactant: SiO 2 molar ratios (MR = 0.12, 0.30, 0.50 and 0.70). Sn was incorporated on MCM-41 by incipient impregnation and by wetness impregnation using a rotaevaporador. The materials were characterized by AAS, XRD, N 2 adsorption-desorption isotherms, TEM, adsorption of pyridine, NH 3 -TPD, UV–vis-DRS and XPS. Materials with Na 2 SiO 3 (MR = 0.70) showed crystalline, textural and structural properties very similar to MCM-41 synthesized with tetraethyl orthosilicate (TEOS). The highest total acidity of materials synthesized with Na 2 SiO 3 compared with materials synthesized with TEOS could be owing to the use of sulfuric acid in the synthesis or the presence of more silanol groups in the solid surface. TOF values obtained in nopol production over materials synthesized with TEOS and Na 2 SiO 3 (MR = 0.70), using wetness impregnation with rotoevaporation, were 420 and 476 h−1, respectively. Low cost paraformaldehyde with larger polymerization degree than Sigma-Aldrich source of formaldehyde was characterized by XRF, XRD, FTIR, TGA and DSC. Polymerization degree seems to affect TOF for nopol production; lower TOF values were obtained with paraformaldehyde with larger polymerization degree. Depolymerization occurs by two parallel reactions: Avrami-Erofeyev (A4) and contracting area (R2) models, with activation energies of 19.8 and 77.5 kJ mol−1, respectively. Sn-MCM-41 synthesized with Na 2 SiO 3 can be used four times without considerable loss of catalytic activity; furthermore, no Sn leaching was detected. [ABSTRACT FROM AUTHOR]

Introduction. Paraformaldehyde has been used in endodontics when effective anaesthesia could not be achieved. However, this agent has many adverse effects including gingival, bone necrosis, osteomyelitis and allergy on account of systemic exposure. Therefore, the use of pastes containing paraformaldehyde should be avoided in contemporary dental practice. Objective. The aim of this case report was to present the application of platelet-rich fibrin(PRF) in combination with a coronally advanced flap in the treatment of gingival and bone necrosis associated with paraformaldehyde containing devitalizing paste toxicity. PRF is an autogenous resorbable membrane composed of platelets, cytokines, leukocytes and growth factors. Results and conclusions. Four weeks following burgery, the wound was completely healed with epithelial cells covering the interdental crater. On the basis of literature and of the present case, it can be stated that the use of PRF significantly reduces postoperative pain and promotes tissue healing. [ABSTRACT FROM AUTHOR]

E‐alkenes were synthesized with up to 100 % E/Z selectivity via ruthenium‐catalyzed partial hydrogenation of different aliphatic and aromatic alkynes under transfer‐hydrogenation conditions. Paraformaldehyde as a safe, cheap and easily available solid hydrogen carrier was used for the first time as hydrogen source in the presence of water for transfer‐hydrogenation of alkynes. Optimization reactions showed the best results for the commercially available binuclear [Ru(p‐cymene)Cl2]2 complex as pre‐catalyst in combination with 2,2‐bis(diphenylphosphino)‐1,1‐binaphthyl (BINAP) as ligand (1 : 1 ratio per Ru monomer to ligand). Mechanistic investigations showed that the origin of E‐selectivity in this reaction is the fast Z to E isomerization of the formed alkenes. Mild reaction conditions plus the use of cheap, easily available and safe materials as well as simple setup and inexpensive catalyst turn this protocol into a feasible and promising stereo complementary procedure to the well‐known Z‐selective Lindlar reduction in late‐stage syntheses. This procedure can also be used for the production of deuterated alkenes simply using d2‐paraformaldehyde and D2O mixtures. [ABSTRACT FROM AUTHOR]

An original procedure was proposed for the synthesis of a series of aminomethanesulfonic acids AlkNHCH2SO3 (Alk = n-Bu, n-Hept, n-Oct, Bn) and N-tris(hydroxymethyl)methylammonium hydroxymethanesulfonate. The structure of the compounds synthesized was examined by elemental analysis, X-ray diffraction, IR spectroscopy, and mass spectrometry. [ABSTRACT FROM AUTHOR]

The synthesis of benzyl alcohols (BAs) is highly vital for their wide applications in organic synthesis and pharmaceuticals. Herein, BAs was efficiently synthesized via hydroxymethylation of phenylboronic acids (PBAs) and paraformaldehyde over a simple RhPPh3 catalyst combined with an inorganic base (NaOH). A variety of BAs with the groups of CH3−, CH3O−, Cl−, Br−, and so on were obtained with moderate to good yields, indicating that the protocol had a good universality. Density functional theory (DFT) calculations proposed the Hayashi‐type arylation mechanism involved the arylation step of PBA and Rh(OH)(PPh3)2 catalyst to form Rh(I)‐bound aryl intermediates and the hydrolysis step of Rh(I)‐bound aryl intermediates and HCHO to generate BA product (the rate‐determining step). The present route provides a valuable and direct method for the synthesis of BAs and expands the application range of paraformaldehyde. [ABSTRACT FROM AUTHOR]

Vaccine-based autoimmune (anti-amyloid) treatments are currently being examined for their therapeutic potential in Alzheimer's disease. In the present study we examined, in a transgenic model of amyloid pathology, the expression of two molecules previously implicated in decreasing the severity of autoimmune responses: TREM2 (triggering receptor expressed on myeloid cells 2) and the intracellular tolerance-associated transcript, Tmem176b (transmembrane domain protein 176b). In situ hybridization analysis revealed that both molecules were highly expressed in plaque-associated microglia, but their expression defined two different zones of plaque-associated activation. Tmem176b expression was highest in the inner zone of amyloid plaques, whereas TREM2 expression was highest in the outer zone. Induced expression of TREM2 occurred co-incident with detection of thioflavine-S-positive amyloid deposits. Transfection studies revealed that expression of TREM2 correlated negatively with motility, but correlated positively with the ability of microglia to stimulate CD4(+) T-cell proliferation, TNF (tumour necrosis factor) and CCL2 (chemokine ligand 2) production, but not IFNgamma (interferon gamma) production. TREM2 expression also showed a positive correlation with amyloid phagocytosis in unactivated cells. However, activating cells with LPS (lipopolysaccharide), but not IFNgamma, reduced the correlation between TREM2 expression and phagocytosis. Transfection of Tmem176b into both microglial and macrophage cell lines increased apoptosis. Taken together, these data suggest that, in vivo, Tmem176b(+) cells in closest apposition to amyloid may be the least able to clear amyloid. Conversely, the phagocytic TREM2(+) microglia on the plaque outer zones are positioned to capture and present self-antigens to CNS (central nervous system)-infiltrating lymphocytes without promoting pro-inflammatory lymphocyte responses. Instead, plaque-associated TREM2(+) microglia have the potential to evoke neuroprotective immune responses that may serve to support CNS function during pro-inflammatory anti-amyloid immune therapies.

Background: Collagen cross-linking of the sclera is a promising approach to strengthen scleral rigidity and thus to inhibit eye growth in progressive myopia. Additionally, cross-linking might inhibit degrading processes in idiopathic melting or in ocular inflammatory diseases of the sclera. Different cross-linking treatments were tested to increase resistance to enzymatic degradation of the rabbit sclera.Methods: Scleral patches from rabbit eyes were cross-linked using paraformaldehyde, glutaraldehyde or riboflavin combined with UV-A-light or with blue light. The patches were incubated with collagenase I (MMP1) for various durations up to 24 h to elucidate differences in scleral resistance to enzymatic degradation. Degraded protein components in the supernatant were detected and quantified using measurements of Fluoraldehyde o-Phthaldialdehyde (OPA) fluorescence.Results: All cross-linking methods reduced the enzymatic degradation of rabbit scleral tissue by MMP1. Incubation with glutaraldehyde (1%) and paraformaldehyde (4%) caused nearly a complete inhibition of enzymatic degradation (down to 7% ± 2.8 of digested protein compared to control). Cross-linking with riboflavin/UV-A-light reduced the degradation by MMP1 to 62% ± 12.7 after 24 h. Cross-linking with riboflavin/blue light reduced the degradation by MMP1 to 77% ± 13.5 after 24 h. No significant differences could be detected comparing different light intensities, light exposure times or riboflavin concentrations.Conclusions: The application of all cross-linking methods increased the resistance of rabbit scleral tissue to MMP1-degradation. Especially, gentle cross-linking with riboflavin and UV-A or blue light might be a clinical approach in future. [ABSTRACT FROM AUTHOR]

The scientific community has responded to the coronavirus disease 2019 (COVID-19) pandemic by rapidly undertaking research to find effective strategies to reduce the burden of this disease. Encouragingly, researchers from a diverse array of fields are collectively working towards this goal. Research with infectious severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is undertaken in high-containment laboratories; however, it is often desirable to work with samples at lower-containment levels. To facilitate the transfer of infectious samples from high-containment laboratories, we have tested methods commonly used to inactivate virus and prepare the sample for additional experiments. Incubation at 80°C, a range of detergents, Trizol reagents, and UV energies were successful at inactivating a high titer of SARS-CoV-2. Methanol and paraformaldehyde incubation of infected cells also inactivated the virus. These protocols can provide a framework for in-house inactivation of SARS-CoV-2 in other laboratories, ensuring the safe use of samples in lower-containment levels. [ABSTRACT FROM AUTHOR]

Lignin is the second most abundant biopolymer and will be an important source for carbon-containing compounds in the future. Based on their similar phenolic structures, lignin has great potential to become a valuable substitute for phenol in phenol-formaldehyde resin adhesives. To meet this aim, the sodium hydroxide (NaOH)-catalyzed reaction of kraft lignin with formaldehyde was studied by using paraformaldehyde (PFA) as a formaldehyde source. The advantage of using PFA, the solid polymer of formaldehyde, is the simple composition of the depolymerized solution. According to the results of differential scanning calorimetry (DSC), the lignin reaction was found to require a high NaOH concentration in order for the reaction with PFA to proceed at reasonably low temperatures compared to the curing temperature of phenol-formaldehyde resins (approximately 150°C). On the other hand, high alkalinity conditions are known to favor the disproportionation of formaldehyde to formic acid and methanol. Due to the moderate reactivity of lignin, the Cannizzaro reaction can compete with the methylolation reaction of lignin. Based on the results of 13C, 31P and 1H-13C heteronuclear single quantum correlation nuclear magnetic resonance (HSQC NMR), methylolation was found to be the main reaction occurring in the lignin-formaldehyde reaction. [ABSTRACT FROM AUTHOR]

Objectives: Most attention has been focused on physiologically generated membrane blebs on the cellular cortex, whereas artificial membrane blebs induced by chemicals are studied to a lesser extent. Results: We found that exposure of HeLa human cervical cancer cells to paraformaldehyde (PFA), followed by incubation in phosphate-buffered saline (PBS) efficiently induced large membrane blebs on the cellular cortex. Intriguingly, sequential exposure of the PFA-treated cells to PBS containing dimethyl sulfoxide (DMSO) facilitated shedding of the blebs from the cellular cortex, yielding a high quantity of large extracellular vesicles in the supernatant, which was applicable to assess the potentials of compounds and proteins as membrane influencers. Similar effects of PFA and DMSO were detected on the cellular cortex of other human, mouse, and fish cells. Conclusions: Our procedure to facilitate membrane blebbing and vesicle shedding by chemicals may be practical for the manipulation of membrane dynamics and the development of vesicle-inspired technologies using a wide variety of cell types. [ABSTRACT FROM AUTHOR]

Cytoplasmic dislocation of NPM1 and PU.1 in NPM1-mutated leukaemia is obscured by paraformaldehyde fixation Keywords: NPM1; PU.1; leukaemia; paraformaldehyde EN NPM1 PU.1 leukaemia paraformaldehyde 578 581 4 04/30/20 20200501 NES 200501 To the Editor: Nucleophosmin (NPM1) is the most recurrently mutated gene in I de novo i acute myeloid leukaemia (AML), producing mutant-NPM1 that aberrantly accumulates in cytoplasm instead of nuclei. NPM1 dislocation into cytoplasm of I NPM1 i -mutated AML cells was first observed by Falini I et al. i ([3]) via immunohistochemical analysis of paraformaldehyde-fixed AML cells. [Extracted from the article]

Purpose: Chemical fixation is a critical step to retaining cellular targets as naturally as possible. Recent developments in microscopy allow sophisticated detection and measuring techniques with which spatio-temporal molecular alterations are conceivable. In this study, we compare two members of aldehyde fixatives [i.e., glyoxal (Gly) and paraformaldehyde (PFA)] to determine whether Gly, a less toxic dialdehyde fixative that is considered to retain immunoreactivity could provide a successful and consistent cell fixation in favor of PFA in various cell preparations and types. Methods: We document the fixation competence of Gly and PFA side-by-side (with or without Triton X-100 permeabilization) in live- and fixed-cell preparations in mouse oocytes, embryos, and human somatic cells (human umbilical cord-derived mesenchymal stromal cells) using protein quantification by Western blot assay and super-resolution microscopy. Results: Although Gly seemed to act faster than PFA, catastrophic consequences were found not acceptable, especially in oocytes and embryos. Due to cell lysate and immunocytochemistry surveys, it was obvious that PFA is superior to Gly in retaining cellular proteins in situ with little/no background staining. In many samples, PFA revealed more reliable and consistent results regarding the protein quantity and cellular localization corresponding to previously defined patterns in the literature. Conclusion: Although the use of Gly is beneficial as indicated by previous reports, we concluded that it does not meet the requirement for proper fixation, at least for the tested cell types and proteins. However, PFA alone with no addition of TX displayed a significant cytoplasmic loss by generating membrane blebs during fixation. [ABSTRACT FROM AUTHOR]

The use of Toxavit for pulpal devitalisation in a 30-year-old woman is presented. Improper use of this material resulted in necrosis of soft tissues and bone. The bone sequestrum was removed and examined under an electron microscope, revealing thick accumulation of plaque on the surface of thebone sequestrum and dissolution of bone material under the influence of microorgansims. [ABSTRACT FROM AUTHOR]