A new environmentally-friendly route to in situ form a high-corrosion-resistant nesquehonite film on pure magnesium.

Magnesium-based materials are promising lightweight structural materials due to their excellent properties. However, their extensive application has been severely limited due to their high corrosion susceptibility. The inadequate corrosion resistance of Mg is mainly attributed to the porous and unprotective native surface film formed on Mg in aggressive environments. Here, we demonstrated a new environment-friendly route for the growth of a continuous nesquehonite (MgCO3·3H2O) protective film on the surface of pure Mg metal at a relatively low temperature via an in situ reaction of the Mg surface with gaseous phase CO2 in humid environments. The protective film consists solely of highly crystalline MgCO3·3H2O that is compact and has an umbrella-like structure. Electrochemical tests showed that compared to the untreated Mg substrate, the protective film can effectively improve the corrosion resistance of the substrate by nearly two orders of magnitude. Additionally, a possible formation mechanism of the nesquehonite film on the pure Mg was proposed and the effect of the carbonation time on the film was investigated. This environmentally-friendly surface treatment method is promising for use in the protection of magnesium-based materials.

B7-H4 deficiency in salivary gland of patients with primary Sjögren's syndrome impairs the regulatory effect on T cells.

AIM: Our previous study confirmed the defect of B7-H4 expression in peripheral blood and salivary glands of patients with primary Sjögren's syndrome (pSS). The aim of this study was to analyze the effect of the deficit expression of B7-H4 on CD4+ T cells. METHODS: CD4+ T cells were purified by magnetic-activated cell sorting MACS. The proliferation and cytokine production of CD4+ T cells co-cultured with purified salivary gland epithelial cells (SGECs) from pSS or non-SS sicca syndrome were detected. RESULTS: By co-culturing the gland cells with CD4+ T cells, we found the proliferation of CD4+ T cells was significantly suppressed. The effect was weaker when SGECs from pSS patients were used compared to that from non-pSS sicca syndrome controls. Simultaneously, the productions of cytokines interleukin (IL)-5, IL-13, IL-17A, IL-6 in supernatant were reduced and also SGECs from pSS patients decreased them less than that from non-SS controls. CONCLUSIONS: The decrease of B7-H4 expression in salivary glands of SS patients contributes to the defect of negatively regulating the inflammation caused by CD4+ T cells, thereby providing new insights into the role of B7-H4 in the inflammatory process of salivary glands in SS.

Mechanistic model for interpreting the toxic effects of sulfonamides on nitrification.

Antibiotics are categorized as pseudopersistent compounds because of their widespread use and continuous emission into the environment. Biological systems such as active sludge and biofilms are still the principal tools used to remove antibiotics in wastewater treatment plants (WWTPs). Consequently, it is important to determine the relationship between toxic effects in biological WWTPs and the structural characteristics of antibiotics. In the present study, toxic effects of 10 sulfonamides (SAs) on nitrification in an active sludge system were studied. The toxicity results (half-effective concentrations, EC50) indicated that the toxicity of sulfadimethoxine (SDM) is approximately 4 times as large as that of sulfadiazine (SD). Based on the toxicity mechanism and the partial least squares regression (PLS) method, an optimum quantitative structure-activity relationship (QSAR) model was developed for the test system. The mechanistic model showed that the pKa, the binding energies between SAs with dihydropteroate synthetase ( [Formula: see text] ) and the binding energies between SAs with ammonia monooxygenase ( [Formula: see text] ) are the key factors affecting the toxic effects of SAs on nitration process in active sludge system, following an order of importance of [Formula: see text] > [Formula: see text] >pKa.

Mechanistic QSAR models for interpreting degradation rates of sulfonamides in UV-photocatalysis systems.

Photocatalysis is one of the most effective methods for treating antibiotic wastewater. Thus, it is of great significance to determine the relationship between degradation rates and structural characteristics of antibiotics in photocatalysis processes. In the present study, the photocatalytic degradation characteristics of 10 sulfonamides (SAs) were studied using two photocatalytic systems composed of nanophase titanium dioxide (nTiO2) plus ultraviolet (UV) and nTiO2/activated carbon fiber (ACF) plus UV. The results indicated that the largest apparent SA degradation rate constant (Kapp) is approximately 5 times as large as that of the smallest one. Based on the degradation mechanism and the partial least squares regression (PLS) method, optimum Quantitative Structure Activity Relationship (QSAR) models were developed for the two systems. Mechanistic models indicated that the degradation rule of SAs in the TiO2 systems strongly relates to their highest occupied molecular orbital (Ehomo), the maximum values of nucleophilic attack (f(+)x), and the minimum values of the most negative partial charge on a main-chain atom (q(C)min), whereas the maximum values of OH radical attack (f(0)x) and the apparent adsorption rate constant values (kad) are key factors affecting the degradation rule of SAs in the TiO2/ACF system.

CD4+CXCR5+ follicular helper T cells in salivary gland promote B cells maturation in patients with primary Sjogren's syndrome.

OBJECTIVE: To examine amount of CD4+CXCR5+Tfh cells and B cells subsets in salivary gland and peripheral blood from patients with primary Sjogren's syndrome (pSS) and to analyze whether the frequency of CD4+CXCR5+Tfh cells is associated with pSS pathologic process. METHODS: The percentages of CD4+CXCR5+Tfh cells and B cell subsets were examined by flow cytometry. B-lymphocyte chemoattraetant (BLC; also called CXCL13), IL-21, IL-6 from the serum of pSS patients was assessed by polymerase chain reaction-enzyme-linked immunosorbent assay (ELISA). RESULTS: The percentages of CD4+CXCR5+Tfh cells in peripheral blood were increased in pSS patients, but decreased after treatment with glucocorticoid and/or immunosuppressive drugs. Abnormal B cell subsets appeared in salivary and peripheral blood of pSS patients. The frequency of salivary CD4+CXCR5+Tfh cells was positively correlated with CD19+CD27+ memory B cells and CD19+CD27high plasma cells. Also increase of salivary CD19+CD27high plasma cells was positively associated with serum ANA titer of pSS patients. CONCLUSIONS: CD4+CXCR5+Tfh cells are significantly increased in salivary and peripheral blood in pSS patients with aberrant CD19+CD27+ memory B cells and CD19+CD27high plasma cells, suggesting that CD4+CXCR5+Tfh cells may contribute to the pathogenesis of pSS by promoting the maturation of B cells.

[Changes in serum levels of resistin and visfatin in pediatric patients with acute Kawasaki disease following intravenous immune globulin treatment].

OBJECTIVE: To determine serum levels of resistin and visfatin in the patients with acute Kawasaki disease before and after intravenous immune globulin (IVIG) treatment. METHODS: A total of 50 children with acute Kawasaki disease were treated with IVIG for 48 hours between January 2011 and January 2013. As controls, 30 healthy children and 30 children with acute infectious diseases were included. Serum levels of resistin and visfatin were measured by ELISA both before and after the treatment. RESULTS: The baseline serum levels of resistin and visfatin were significantly higher in patients with acute Kawasaki disease than in the two control groups of subjects (i.e., healthy children and patients with acute infectious diseases; P<0.05). In the 50 patients with Kawasaki disease, 38 were not responding and 12 were responding. Serum resistin levels before treatment were significantly higher in non-responders than those in responders (P<0.05). A significant decrease in serum levels of resistin after treatment was observed in IVIG responders (P<0.05). Serum visfatin levels were not significantly different between IVIG responders and non-responders (P>0.05). Additionally, serum resistin and visfatin levels were not significantly different between acute Kawasaki disease patients with and without coronary artery lesions. CONCLUSIONS: Resistin and visfatin may play important roles in the development of Kawasaki disease and serum resistin may be used as a novel outcome indicator of the IVIG treatment.

CD4(+)CD25 (+)CD127 (low/-) T cells: a more specific Treg population in human peripheral blood.

The quantitative identification and enrichment of viable regulatory T cells (Treg) requires reliable surface markers that are selectively expressed on Treg. Foxp3 is the accepted marker of nTreg, but it cannot be used to isolate cells for functional studies. In this study, we compared four staining profiles of Treg, including CD4(+)CD25(high) T cells, CD4(+)CD39(+) T cells, CD4(+)CD73(+) T cells, and CD4(+)CD25(+)CD127(low/-) T cells. We found that CD4(+)CD25(+)CD127(low/-) T cells expressed the highest level of Foxp3 and had the strongest correlation with CD4(+)CD25(+)Foxp3(+) T cells, the accepted identifying characteristics for "real" nTreg cells. Moreover, functional data showed that CD4(+)CD25(+)CD127(low/-) T cells could effectively suppress the proliferation of CD4(+)CD25(-) T cells, suggesting that compared with the other three populations, CD4(+)CD25(+)CD127(low/-) T cells best fit the definition of naturally occurring regulatory T cells in human peripheral blood. Finally, we showed that CD4(+)CD25(+)CD127(low/-) can be used to quantitate Treg cells in individuals with systemic lupus erythematosus supporting the use of CD4(+)CD25(+)CD127(low/-) to identify human Treg cells.

[B7-H4 expression of salivary gland and sera in patients with primary Sjogren's syndrome].

OBJECTIVE: To detect the expression of B7-H4 in salivary gland and sera in patients with primary Sjogren's syndrome (pSS). METHODS: A total of 40 pSS patients were referred to our department from June 2009 to January 2011. Immunohistochemistry and flow cytometry were used to detect the expression of B7-H4 in salivary gland from pSS patients and disease controls. Enzyme-linked immunosorbent assay (ELISA) was used to detect soluble B7-H4 of serum from pSS patients and healthy donors. RESULTS: Immunohistological staining revealed that B7-H4 antigen was restricted to tubular epithelium. The B7-H4 positive expression of tubules in salivary gland biopsies from pSS patients (18 ± 14)% were lower than that of controls (85 ± 13)% (P < 0.05). Flow cytometry revealed that the B7-H4 expression of cell suspensions from salivary gland from pSS patients (42 ± 21)% were lower than that of controls (48 ± 22)% (P < 0.01). And the serum level of soluble B7-H4 detected in pSS patients (49 ± 31)µg/L significantly decreased than that in healthy donors (71 ± 27) µg/L (P < 0.05) and positively correlated with saliva and tear flow rates (P < 0.01) respectively. CONCLUSION: The expression of B7-H4 molecule may play some roles in the progression of pSS. And a further understanding of its mechanism helps to elucidate the pathogenesis of pSS.