Construction and preservation of a stable and highly expressed recombinant Helicobacter pylori vacuolating cytotoxin A with apoptotic activity

Background H. pylori is closely related to the occurrence and development of various digestive gastritis, peptic ulcer and mucosa-associated lymphoid tissue (MALT) lymphoma. H. pylori is also a class I carcinogen of gastric cancer. VacA is the only exocrine toxin of H. pylori, which plays a very important role in the pathogenesis of H. pylori. The production of VacA in natural circumstances is complex with heavy workload and low yield. Therefore, it is very important to obtain recombinant VacA protein which is stable and biologically active. This study therefore aims to explore the expression, purification and stable storage of VacA toxin of H. pylori in E.coli, and to provide experimental basis for further exploration of the role of VacA in H. pylori -induced inflammation of cancer. Results A 2502-bp fragment and VacA gene were identified. An 89.7-kDa VacA34–854 recombinant protein was expressed and purified from the recombinant engineering bacteria and was preserved stably in 50 mM acetic acid buffer (pH 2.9). The amount of the recombinant protein was larger in the inclusion bodies than in the supernatant. In addition, after a 24-h culture with VacA recombinant protein, GES-1 cells demonstrated evidence of apoptosis including early nuclear immobilization and clustering under inverted microscope and TEM. It was found that VacA recombinant protein induced apoptosis by TUNEL assay. Conclusions A VacA recombinant protein that is stably and highly expressed and possesses pro-apoptotic activity is successfully constructed. The protein is stably preserved in 50 mM acetic acid buffer (pH 2.9).

Construction and Preservation of a Stable and Highly Expressed Recombinant Helicobacter pylori Vacuolating Cytotoxin A with Apoptotic Activity

Background: VacA is the only exocrine toxin of H. pylori, which plays a very important role in the customization of H. pylori in the gastric mucosa, contributing to the pathogenesis of gastritis-cancer. Studies about vacA structure and function was hindered by the lack of efficient production system. In this study, we developed methodology for expression, purification and stable storage of a functionally active vacA toxin in E.coli.Results: A 2502-bp fragment and vacA gene were identified. An 89.7-kDa VacA34-854 recombinant protein was expressed and purified from the recombinant engineering bacteria and was preserved stably in 50 mM acetic acid buffer (pH 2.9). The amount of the recombinant protein was larger in the inclusion bodies than in the supernatant. In addition, after a 24-h culture with VacA recombinant protein, GES-1 cells demonstrated evidence of apoptosis including early nuclear immobilization and clustering under inverted microscope and TEM. It was found that VacA recombinant protein induced apoptosis by TUNEL assay.Conclusions: A VacA recombinant protein that is stably and highly expressed and possesses pro-apoptotic activity is successfully constructed. The protein is stably preserved in 50 mM acetic acid buffer (pH 2.9).

Surface-Step-Induced Magnetic Anisotropy in Epitaxial LSMO Deposited on Engineered STO Surfaces

Changes in stoichiometry, temperature, strain and other parameters dramatically alter properties of LSMO perovskite. Thus, the sensitivity of LSMO may enable control of the magnetic properties of the film. This work demonstrates the capabilities of interface engineering to achieve the desired effects. Three methods of preparing STO substrates were conducted, i.e., using acid, buffer solution, and deionized water. The occurrence of terraces and their morphology depend on the preparation treatment. Terraces propagate on deposited layers and influence LSMO properties. The measurements show that anisotropy depends on the roughness of the substrate, the method of preparing the substrate, and oxygen treatment. The collected results suggest that the dipolar mechanism may be the source of LSMO anisotropy.

Chemical characteristics of thermo-hydrolytically recycled particles

Particles from waste laminated particleboards were recovered using various thermo-hydrolytic treatments. The size distribution and three main chemical properties, such as pH, buffer capacity, and nitrogen content of the control and resulting particles were determined. The effects of treatment temperature and duration on the chemical properties of recycled particles were investigated. The effects of the resulting particles on the gel time of urea-formaldehyde (UF) resin were also measured. The test results suggested that the pH of particles after hot water soaking pre-treatment and the different thermo-hydrolytic treatments increased to different extents, with the exception of the particles treated at 140 °C for 50 min and 160 °C for 20 min. The acid buffer capacity and base buffer capacity of particles treated at 140 °C for 50 min and 160 °C for 20 min had no statistical difference, but they were much higher than those of other types of treated particles. A high treatment temperature facilitated the decomposition of wood polymers and UF resin. Both temperature and treatment duration had significant effects on pH, acid buffer capacity, and base buffer capacity of wood particles. Wood particles recycled at a high temperature had a negative effect on the gel time of UF resin.

Mechanical and Functional Properties of a Novel Apatite-Ionomer Cement for Prevention and Remineralization of Dental Caries

Especially in pediatric dentistry, prevention by the control of initial lesions prior to cavitation is very important, and application of a pit and fissure sealant is essential to achieve this. Numerous reports have suggested that resin-based sealants are inferior to sealants based on glass-ionomer cement (GIC), because of GIC’s many advantages, such as fluoride ion release properties and its good adhesion to tooth structures. However, the use of GIC is impeded due to its low flexural strength and fracture toughness. In this paper, we developed and characterized an apatite-ionomer cement (AIC) that incorporates hydroxyapatite (HAp) into the GIC; this development was aimed at not only reinforcing the flexural and compressive strength but also improving some functional properties for the creation of the material suitable for sealant. We examined the influence of differences in the compounding conditions of GIC powder, liquid, and HAp on flexural and compressive strengths, fracture toughness, fluoride ion release property, shear bond strength to bovine enamel, surface pH of setting cements, and acid buffer capability. These methods were aimed at elucidating the reaction mechanism of porous spherical-shaped HAp (HApS) in AIC. The following observations were deduced. (1) HAp can improve the mechanical strengths of AIC by strengthening the cement matrix. (2) The functional properties of AIC, such as acid buffer capability, improved by increasing the releasing amounts of various ions including fluoride ions. The novel AIC developed in this study is a clinically effective dental material for prevention and remineralization of tooth and initial carious lesion.