Synthesis, antibacterial activity, and biocompatibility of new antibacterial dental monomers.

PURPOSE: To synthesize a small library of antibacterial dental monomers based on quaternary ammonium salts and to test their antibacterial activity against cariogenic bacteria. METHODS: Five new antibacterial monomers were synthesized and characterized by NMR, IR and HRMS. RESULTS: Cytotoxicity assays using human gingival fibroblast cells showed that these new antibacterial monomers were biocompatible at concentrations of 10⁻5 M and displayed less cytotoxicity than BisGMA, a common dental monomer. When analyzed in vitro, all new monomers demonstrated strong inhibitory activity against biofilm formation by cariogenic Streptococcus mutans and Lactobacillus casei. Results indicated that antibacterial monomers containing a long alkyl (i.e. hexadecyl) chain are superior to their shorter-chain counterparts. The cross-linking monomers based on glycerol dimethacrylate also consistently outperformed their monomethacrylate analogs. Finally, the ammonium salts containing the dimethylbenzyl moiety were superior to the similar structures containing 1,4-diazabicyclo[2.2.2]octane (DABCO) in some cases. CLINICAL SIGNIFICANCE: All five new monomers were deemed biocompatible at concentrations of 10⁻5 M or less, and most had better biocompatibility than BisGMA. Dimethacrylate monomers 5 and 6 generally demonstrated high antibacterial activities, with the highest activity shown for the most lipophilic monomer 6, and these new antibacterial monomers have potential future application in dental composites and bonding agents.

Efficacy and safety of Runzao Zhiyang capsule for chronic urticaria: a systematic review and meta-analysis of randomized controlled trials.

Background: Chronic urticaria (CU) is a commonly seen skin disorder featured by recurring wheals, with or without angioedema, lasting for at least 6 weeks. Runzao Zhiyang capsule (RZC) has been widely applied to treat patients with CU. This study is aimed at systematically evaluating the efficacy and safety of RZC in treating CU. Materials and Methods: Randomized controlled trials (RCTs) of RZC on treating CU from Chinese and English databases were searched. Data were collected by two independent researchers. The Cochrane Collaboration tool was adopted for evaluating the risk of bias. The meta-analysis was performed with Review Manager 5.3 software. Sensitivity analysis and publication bias assessment were conducted by Stata 14.0 software. Results: Totally 27 studies were included in the analysis, involving 2,703 patients. The pooled results showed that compared with second-generation H1-antihistamines (sgAHs) therapy alone, RZC combined with sgAHs is more effective in improving the total effective rate (RR = 1.32, 95% CI: 1.25 to 1.39, p < 0.00001), the quality of life measured by Dermatology Life Quality Index (DLQI) (MD = -2.63, 95% CI: -3.68 to -1.58, p < 0.00001) and the serum IFN-γ level (SMD = 3.10, 95% CI: 1.58 to 4.62, p < 0.0001), and reducing the recurrence rate (RR = 0.39, 95% CI: 0.27 to 0.55, p < 0.00001), the serum total IgE level (SMD = -2.44, 95% CI: -3.51 to -1.38, p < 0.00001), the serum IL-4 level (SMD = -2.96, 95% CI: -4.10 to -1.83, p < 0.00001), and the incidence of adverse events including dizziness, fatigue, dry mouth, and constipation (RR = 0.53, 95% CI: 0.33 to 0.85, p = 0.009; RR = 0.46, 95% CI: 0.26 to 0.84, p = 0.01; RR = 0.57, 95% CI: 0.34 to 0.95, p = 0.03; RR = 0.24, 95% CI: 0.07 to 0.85, p = 0.03). Conclusion: The current evidence indicates that RZC may be an efficient therapeutic regimen in patients with CU. Nevertheless, owing to the suboptimal quality of the included studies, more large-scale, well-designed RCTs are required to verify the obtained findings. Systematic Review Registration: https://www.crd.york.ac.uk/PROSPERO/; Identifier: CRD42022313177.

Managing the difficult airway: A survey of doctors with different seniority in China.

ABSTRACT: Although equipment and human resources are vital elements of difficult airway management (DAM). But the approach and practice of DAM are more important. So, we conducted the present survey to address anesthesiologists of different working years in this knowledge gap.This nationwide cross-sectional study was conducted from October 27, 2016 to November 27, 2016. The survey was completed online in New Youth Anesthesia Forum including DAM assessment, anticipated and unanticipated DAM, difficult airway algorithm, use of the front of neck access (FONA) technique and training, DAM outside the operation room, and difficult extubation management.We received 1935 replies (44%). Mouth opening and Mallampati classification were the most common methods to evaluate difficult airways. When suffering from unanticipated difficult airway 63% less than 10 years anesthesiologists (LA) and 65% more than 10 years anesthesiologists (MA) would ask for help after trying 1 to 2 times (P = .000). More than 70% of LA and MA respondents reported preferring cannula cricothyrotomy to deal with emergency airway, 507 (41.6%) MA respondents reported that they used FONA techniques to save patients' lives (P = .000). Nearly 70% respondents worried full stomach when intubated outside operation room and more than 80% respondents selected auscultation to identify the placement. More than 80% respondents had not used Bougie to assist extubation. A 73.2% respondents know ABS algorithm and 96.4% know Chinese airway expert consensus among MA respondents, this was significant to LA respondents (P = .000).The respondents in the LA and MA have a training gap in their evaluation of difficult airways, trained and used FONA emergency skills, facilitated of the airway guidelines at home and abroad. Also, we should provide more airway theory and skill training to our young doctors to advanced airway skills.

Fabrication of cross-linked polyethyleneimine microfibers by reactive electrospinning with in situ photo-cross-linking by UV radiation.

The objective of this work is to demonstrate the feasibility of fabrication of cross-linked polyethyleneimine microfibers by a reactive photo-electrospinning technology. Linear polyethyleneimine (L-PEI) has been grafted with cross-linkable methacrylate moiety by reaction with glycidyl methacrylate (GMA), enabling the polymer to cross-link upon UV exposure. The photo-cross-linking reaction was characterized by a photo-rheometer. Neat L-PEI or methacrylated L-PEI tends to aggregate rendering it very difficult to electrospin into microfibers. A high molecular weight polyvinylpyrrolidone (PVP) is an efficient chain entanglement enhancer for both L-PEI and methacrylated L-PEI and helpful to maintain fibrous structure. An optimized composition consisted of 10% methacrylated L-PEI (less than 14.8% methacrylation of total L-PEI) combined with 2% PVP and 1% photoinitiator in ethanol was successfully electrospun into smooth cross-linked microfibers using the reactive electrospinning device. Diameters of cross-linked fibers can be controlled from 419 nm to 2 µm depending on methacrylation degree and UV irradiation intensity. The resultant cross-linked L-PEI microfibers have demonstrated significantly improved solvent resistance, thermal stability, and mechanical properties. The distinguished characteristics of this novel reactive electrospinning technology are the high cross-linking efficiency and minimal toxic chemical residues in the products. The stability of the fibers can be readily modified and controlled by the cross-linking degree, which is of great importance for biomedical applications.

3D Finite Element Analysis of the Modular Prosthesis with Tooth Mechanism of the Femoral Shaft.

OBJECTIVES: To evaluate the mechanical properties and provide a theoretical basis of a diaphyseal prosthesis with tooth mechanism using the finite element analysis method from the point of view of biomechanics. METHODS: A 3D digital femur model was generated based on a 28-year-old healthy man's femoral computed tomography (CT) data in Mimics 17.0 and the customized diaphyseal prostheses with/without tooth mechanism were designed in SolidWorks 2016. The 3D femur model after 8 cm osteotomy in the middle of its shaft and the prostheses with/without tooth mechanism was imported into Abaqus 2016 and the finite element analysis models were established. Three biomechanical tests (compression test, torsion test, and 3P-bending test) under broken load were simulated in FEA to evaluate the performance of the prostheses. RESULTS: The stress distributions of the two prostheses were similar and the maximum von Mises stresses placed on them were very close in each test. The maximum von Mises stresses on the prosthesis with tooth mechanism were 31.55, 319.7, and 447.4 MPa, respectively, and those on the prosthesis without tooth mechanism were 26.26, 300.4, and 455.2 MPa, respectively, in the compression, torsion, and 3P-bending tests. The maximum von Mises stresses on them were far below the ultimate tensile strength or ultimate compressive strength of the titanium alloy. CONCLUSIONS: The diaphyseal prosthesis with tooth mechanism is helpful to adjust the rotation of the long bone during operation. Compared with the conventional diaphyseal prosthesis (without tooth mechanism), the diaphyseal prosthesis with tooth mechanism also has a good biomechanical performance and does not increase the risk of prosthetic failure.

[Synthesis of methotrexate-poly (ethylene glycol) conjugate and their anti-tumor activity in vitro].

To improve the physical property and bioactivity of methotrexate, this paper investigated the new formation of conjugate methotrexate-poly (ethylene glycol) and in vitro anti-tumor activity of the synthesized conjugate. The conjugate of methotrexate-poly (ethylene glycol), which was verified by the spectroscopy analysis of UV, IR and 13C NMR, was synthesized by chemical catalysis and micro-wave irritation. The determination for the conjugate of solubility in water and distribution coefficient in octanol-water system of the conjugate was done to examine its deliquescence property. The solubility in water and the distribution coefficient of the conjugate was greatly improved, which was increased by 128 folds and 5 folds, respectively. The in vitro anti-tumor activity of the conjugate was tested by mouse L(1210) leukaemia cells, and the synthesized conjugate showed the same anti-tumor activity as the original methotrexate. Compared to the reported literature, the modification of methotrexate by poly (ethylene glycol) is more rapid and convenient.

Photo-cross-linked Antibacterial Zein Nanofibers Fabricated by Reactive Electrospinning and its Effects against Streptococcus mutans.

Native zein electrospun nanofibers have shown poor solvent resistance and low mechanical strength. Compared to other toxic cross-linkers, a safer method of stabilizing zein based fibers while retaining or with improved mechanical strength is needed to convert these materials for biomedical applications where culture media or body fluids may be present. We report here a method of fabricating non-toxic zein nanofibers using reactive electrospinning coupled with in situ photo-cross-linking. The cross-linked zein nanofibers exhibited significantly improved mechanical strength and sustained morphology against water and aqueous ethanol solution. This process doesn't require additional conventional cross-linking agents to form cross-linking network, which is advantageous for biomedical applications. Antimicrobial monomer with photo-reactive moiety was coupled with methacrylate zein nanofibers and showed strong inhibitory activity against cariogenic Streptococcus mutans. Cytotoxicity test with human gingival fibroblasts revealed high biocompatibility.

Physical characterization of coupled poly(lactic acid)/starch/maleic anhydride blends plasticized by acetyl triethyl citrate.

Acetyl triethyl citrate (ATC) was used as a plasticizer for poly(lactic acid) (PLA)/starch blends coupled with maleic anhydride and an initiator of 2,5-bis(tert-butylperoxy)-2,5-dimethylhexane (L101). Elongation of the blend at break was markedly increased when the ATC content was above the 8% loading level, which is referred to as the percolation threshold. The extended elongation was achieved at the expense of tensile strength and elastic modulus. Thermal transitions of the blend, including the glass transition temperature (T(g)), cold crystallization temperature (T(c)) and melting temperature (T(m)), decreased with ATC content. Thermally induced ATC migration affected the thermal behavior of the plasticized blends and reduced elongation and tensile strength, whereas the elasticity modulus increased. ATC migration increased with ambient temperature, which was controlled by the activation energy of the blend system. Leaching of ATC was slow at room temperature in distilled water, but significant in boiling water. Additionally, the leaching rate was also directly proportional to the ATC content of the blend. Glass transition temperatures of PLA/starch/MA/L101 blends with various acetryl triethyl citrate contents.

Comparison of the surface hardness among 3 materials used in an experimental apexification model under moist and dry environments.

INTRODUCTION: Procedures used in single-visit or multiple-visit approaches to apical barrier creation were used with an experimental apexification model to test the surface hardness of 3 materials. The purpose of this study was to examine the microhardness of the materials after setting in moist or dry conditions. METHODS: A simulated open apex and periapical environment model was created using polyethylene tubes placed into a porous block filled with phosphate-buffered saline. White ProRoot Mineral Trioxide Aggregate (MTA; Dentsply Tulsa Dental, Tulsa, OK), EndoSequence Root Repair Material (ESRRM; Brasseler USA, Savannah, GA), and Biodentine (BD; Septodont, Louisville, CO) were mixed and placed into the apical 4 mm of the tubes (N = 15). The moist group had a damp cotton pellet above the test materials (mineral trioxide aggregate or ESSRM) with Fuji II LC (GC America, Alsip, IL) sealing the coronal segment. The dry group had gutta-percha placed directly against the test materials with amalgam sealing the coronal segment. After 10 days of storage in 100% humidity at 37°C, samples were sectioned, and microhardness was independently measured at 2 mm and 4 mm from the apical end. Differences were assessed using analysis of variance and a Tukey post hoc test (α = .05). RESULTS: Analysis of variance analyses showed no significant effect of wet or dry conditions on resultant material hardness. A Tukey post hoc test showed that using ESRRM and BD would not result in a significant difference in hardness, but using MTA would result in statistically significant different hardness values when compared with ESRRM or BD. CONCLUSIONS: Either a moist or dry environment could allow hardening of materials; thus, both methods could be acceptable for clinical treatment procedures.

In vitro fracture resistance of three commercially available zirconia crowns for primary molars.

PURPOSE: The purpose of this study was to measure the fracture resistance of primary mandibular first molar zirconia crowns from three different manufacturers-EZ Pedo (EZP), NuSmile (NSZ), and Kinder Krowns (KK)-and compare it with the thickness of the zirconia crowns and the measured fracture resistance of preveneered stainless steel crowns (SSCs). METHODS: The thickness of 20 zirconia crowns from three manufacturers were measured. The mean force required to fracture the crowns was determined. Preveneered NuSmile (NSW) SSCs were tested as a control. RESULTS: EZP crowns were significantly thicker in three of the six measured locations. The force required to fracture the EZP crown was significantly higher than that required for NSZ and KK. There was a positive correlation between fracture resistance and crown thickness in the mesial, distal, mesioocclusal, and distoocclusal dimensions. None of the zirconia crowns proved to be as resistant to fracture as the preveneered SSCs. CONCLUSIONS: Statistically significant differences were found among the forces required to fracture zirconia crowns by three different manufacturers. The increase in force correlated with crown thickness. The forces required to fracture the preveneered stainless steel crowns were greater than the forces required to fracture all manufacturers' zirconia crowns.

Development of a novel liposomal nanodelivery system for bioluminescence imaging and targeted drug delivery in ErbB2-overexpressing metastatic ovarian carcinoma.

Liposomes as targeted drug delivery systems are an emerging strategy in the treatment of cancer to selectively target tumors or genes. In this study, we generated the recombinant protein, EC1-GLuc, by fusing the EC1 peptide, an artificial ligand of ErbB2, with Gaussia luciferase (GLuc). The purified EC1-GLuc was conjugated with a nickel-chelating liposome to construct the EC1-GLuc-liposome. In vitro experiments revealed that the EC1-GLuc-liposome selectively targeted and internalized into ErbB2-overexpressing SKOv3 cells for bioluminescence imaging. A cell-impermeable fluorescence dye (HPTS) encapsulated in the EC-GLuc-liposome was efficiently delivered into the SKOv3 cells. In addition, the EC1-GLuc-liposome also targeted metastatic SKOv3 tumors for bioluminescence imaging and effectively delivered HPTS into metastatic tumors in vivo. Therefore, the present study demonstrates the novel EC1-GLuc-liposome to be an effective theranostic system for monitoring and treating ErbB2-overexpressing metastatic ovarian carcinoma through a combination of targeted molecular imaging and DDS.

Novel dental composites reinforced with zirconia-silica ceramic nanofibers.

OBJECTIVE: To fabricate and characterize dental composites reinforced with various amounts of zirconia-silica (ZS) or zirconia-yttria-silica (ZYS) ceramic nanofibers. METHODS: Control composites (70 wt% glass particle filler, no nanofibers) and experimental composites (2.5, 5.0, and 7.5 wt% ZS or ZYS nanofibers replacing glass particle filler) were prepared by blending 29 wt% dental resin monomers, 70 wt% filler, and 1.0 wt% initiator, and polymerized by either heat or dental curing light. Flexural strength (FS), flexural modulus (FM), energy at break (EAB), and fracture toughness (FT) were tested after the specimens were stored in 37°C deionized water for 24h, 3 months, or 6 months. Degree of conversion (DC) of monomers in composites was measured using Fourier transformed near-infrared (FT-NIR) spectroscopy. Fractured surfaces were observed by field-emission scanning electron microscope (FE-SEM). The data were analyzed using ANOVA with Tukey's Honestly Significant Differences test used for post hoc analysis. RESULTS: Reinforcement of dental composites with ZS or ZYS nanofibers (2.5% or 5.0%) can significantly increase the FS, FM and EAB of dental composites over the control. Further increase the content of ZS nanofiber (7.5%), however, decreases these properties (although they are still higher than those of the control). Addition of nanofibers did not decrease the long-term mechanical properties of these composites. All ZS reinforced composites (containing 2.5%, 5.0% and 7.5% ZS nanofibers) exhibit significantly higher fracture toughness than the control. The DC of the composites decreases with ZS nanofiber content. SIGNIFICANCE: Incorporation of ceramic nanofibers in dental composites can significantly improve their mechanical properties and fracture toughness and thus may extend their service life.

Catalytic removal of acetaldehyde in saliva by a Gluconobacter strain.

Acetaldehyde (AA) accumulates in the oral cavity after alcohol intake and is responsible for an increased risk of alcohol-related upper aerodigestive tract (UDAT) cancer among aldehyde dehydrogenase 2-inactive heterozygotes in particular. Thus, the removal of AA from the saliva to a level below its mutagenic concentration (50 µM) after drinking is a potentially straightforward method for reducing the risk of alcohol-related UDAT cancer. Although microbial cells with AA-decomposing activity could potentially serve as a useful agent for the catalytic removal of AA from the saliva without the supplemental addition of cofactors, these cells generally exhibit strong AA-producing activity from ethanol, which is present in excess (50mM) over AA (100 µM) in the saliva after drinking. In this study, we observed that Gluconobacter kondonii (GK) cells efficiently decomposed salivary AA (100-390 µM) without the supplemental addition of cofactors irrespective of the type of alcoholic beverages consumed, even in the presence of an excess of ethanol (63 mM). Hydrogen peroxide, which is carcinogenic in animal experiments, was not produced because of the AA removal. The GK cells incubated at 45 °C and pH 3.5 for 15 h were killed, but they retained 80% of their original AA-decomposing activity. The treated cells were used as nonviable microcapsules that harbor a membrane-bound AA-decomposing activity.

Reactive electrospinning and biodegradation of cross-linked methacrylated polycarbonate nanofibers.

The objectives of this study were to fabricate cross-linked biodegradable polycarbonate nanofibers and to investigate their biodegradability by different enzymes. Poly(2,3-dihydroxycarbonate) was synthesized from naturally occurring l-tartaric acid. The hydroxyl groups on the functional polycarbonate were converted to methacrylate groups to enable the polymer to cross-link under UV irradiation. Smooth cross-linked methacrylated polycarbonate nanofibers (300-1800 nm) were fabricated by a reactive electrospinning process with in situ UV radiation from a mixed solution of linear methacrylated polycarbonate (MPC) and poly(ethylene oxide) (PEO) (MPC:PEO = 9:1) in methanol/chloroform (50/50). These cross-linked nanofibers have shown excellent solvent resistance and their solubility decreases with increasing degree of cross-linking. The thermal properties of linear and cross-linked polycarbonate nanofibers were investigated by differential scanning calorimetry and thermogravimetric analysis. The cross-linked polycarbonate nanofibers show no melting point below 200 °C and their decomposition temperature increases with increasing cross-linking degree. Their biodegradation products by five different enzymes were analyzed using liquid chromatography-mass spectrometry (LC-MS). The biodegradability of the polycarbonate nanofibers decreases with increasing cross-linking degree. These nanofibers were found to support human fibroblast survival and to promote cell attachment. This study demonstrates that cross-linked biodegradable polycarbonate nanofibers with different chemical properties and biodegradability can be fabricated using the novel reactive electrospinning technology to meet the needs of different biomedical applications.

A xyloglucan endotransglucosylase/hydrolase involves in growth of primary root and alters the deposition of cellulose in Arabidopsis.

Xyloglucan endotransglucosylase/hydrolases (XTHs) are a class of enzymes that mediate the construction and restructure of the cellulose/xyloglucan framework by splitting and reconnecting xyloglucan molecule cross-linking among cellulose microfibrils. Remodification of cellulose microfibrils within cell-wall matrices is realized to be one of the most critical steps in the regulation of cells expansion in plants. Thirty-three XTH genes have been found in Arabidopsis thaliana but their roles remain unclear. AtXTH21 (At2g18800), an Arabidopsis XTH gene that mainly expresses in root and flower, exhibits different expression profiles from other XTH members under hormone treatment. We examined loss-of-function mutants using T-DNA insertion lines and overexpression lines and found that the AtXTH21 gene played a principal role in the growth of the primary roots by altering the deposition of cellulose and the elongation of cell wall.

Mechanical properties of poly(lactic acid)/starch composites compatibilized by maleic anhydride.

Blending poly(lactic acid) (PLA) with wheat starch compatibized by maleic anhydride (MA) was performed with a lab-scale co-extruder. An initiator, 2,5-bis(tert-butylperoxy)-2,5 dimethylhexane (L101), was used to improve compatability among PLA, starch and MA. Interfacial adhesion between PLA and starch was significantly improved. Mechanical properties increased markedly compared to the virgin composites of PLA/starch. The PLA/starch composites at a constant ratio of 55/45 compatibilized by 1% MA and initiated by 10% L101 (MA basis) resulted in the highest tensile strength and elongation.

Chemical modification of L-asparaginase from Escherichia coli with a modified polyethyleneglycol under substrate protection conditions.

L-Asparaginase was chemically modified with 2,4-bis(O-methoxypolyethyleneglycol)-6-chloro-S-triazine (mPEG2) in the presence of L-asparagine. Optimal modification was performed under the condition that the molar ratio of mPEG2/-NH2 is 10. The modified enzyme retained 33% of initial enzymatic activity with complete abolishment of immunogenicity. In vitro half-life increment from 4.6 h to 33 h has been obtained.