Bone loss and aggravated autoimmune arthritis in HLA-DRβ1-bearing humanized mice following oral challenge with Porphyromonas gingivalis

BACKGROUND: The linkage between periodontal disease and rheumatoid arthritis is well established. Commonalities among the two are that both are chronic inflammatory diseases characterized by bone loss, an association with the shared epitope susceptibility allele, and anti-citrullinated protein antibodies. METHODS: To explore immune mechanisms that may connect the two seemingly disparate disorders, we measured host immune responses including T-cell phenotype and anti-citrullinated protein antibody production in human leukocyte antigen (HLA)-DR1 humanized C57BL/6 mice following exposure to the Gram-negative anaerobic periodontal disease pathogen Porphyromonas gingivalis. We measured autoimmune arthritis disease expression in mice exposed to P. gingivalis, and also in arthritis-resistant mice by flow cytometry and multiplex cytokine-linked and enzyme-linked immunosorbent assays. We also measured femoral bone density by microcomputed tomography and systemic cytokine production. RESULTS: Exposure of the gingiva of DR1 mice to P. gingivalis results in a transient increase in the percentage of Th17 cells, both in peripheral blood and cervical lymph nodes, a burst of systemic cytokine activity, a loss in femoral bone density, and the generation of anti-citrullinated protein antibodies. Importantly, these antibodies are not produced in response to P. gingivalis treatment of wild-type C57BL/6 mice, and P. gingivalis exposure triggered expression of arthritis in arthritis-resistant mice. CONCLUSIONS: Exposure of gingival tissues to P. gingivalis has systemic effects that can result in disease pathology in tissues that are spatially removed from the initial site of infection, providing evidence for systemic effects of this periodontal pathogen. The elicitation of anti-citrullinated protein antibodies in an HLA-DR1-restricted fashion by mice exposed to P. gingivalis provides support for the role of the shared epitope in both periodontal disease and rheumatoid arthritis. The ability of P. gingivalis to induce disease expression in arthritis-resistant mice provides support for the idea that periodontal infection may be able to trigger autoimmunity if other disease-eliciting factors are already present

Intercomparison of cloud model simulations of Arctic mixed‐phase boundary layer clouds observed during SHEBA/FIRE‐ACE

An intercomparison of six cloud‐resolving and large‐eddy simulation models is presented. This case study is based on observations of a persistent mixed‐phase boundary layer cloud gathered on 7 May, 1998 from the Surface Heat Budget of Arctic Ocean (SHEBA) and First ISCCP Regional Experiment ‐ Arctic Cloud Experiment (FIRE‐ACE). Ice nucleation is constrained in the simulations in a way that holds the ice crystal concentration approximately fixed, with two sets of sensitivity runs in addition to the baseline simulations utilizing different specified ice nucleus (IN) concentrations. All of the baseline and sensitivity simulations group into two distinct quasi‐steady states associated with either persistent mixed‐phase clouds or all‐ice clouds after the first few hours of integration, implying the existence of multiple states for this case. These two states are associated with distinctly different microphysical, thermodynamic, and radiative characteristics. Most but not all of the models produce a persistent mixed‐phase cloud qualitatively similar to observations using the baseline IN/crystal concentration, while small increases in the IN/crystal concentration generally lead to rapid glaciation and conversion to the all‐ice state. Budget analysis indicates that larger ice deposition rates associated with increased IN/crystal concentrations have a limited direct impact on dissipation of liquid in these simulations. However, the impact of increased ice deposition is greatly enhanced by several interaction pathways that lead to an increased surface precipitation flux, weaker cloud top radiative cooling and cloud dynamics, and reduced vertical mixing, promoting rapid glaciation of the mixed‐phase cloud for deposition rates in the cloud layer greater than about 1 − 2 × 10−5 g kg−1 s−1 for this case. These results indicate the critical importance of precipitation‐radiative‐dynamical interactions in simulating cloud phase, which have been neglected in previous fixed‐dynamical parcel studies of the cloud phase parameter space. Large sensitivity to the IN/crystal concentration also suggests the need for improved understanding of ice nucleation and its parameterization in models

Green synthesis of silver nanoparticles in xylan solution via Tollens reaction and their detection for Hg2+

This work reported a facile and green method to prepare highly stable and uniformly distributed Ag nanoparticles (AgNPs), in which a biopolymer xylan was used as the stabilizing and reducing agent via the Tollens reaction under microwave irradiation. Different variables were evaluated to optimize the reaction conditions. Complete characterization was performed using UV-Vis, XRD, TEM, size distribution analysis and XPS. The results revealed that AgNPs were well dispersed with diameters of 20-35 nm due to the packing of xylan. The optimal conditions were as follows: microwave irradiation temperature was 60-70 degrees C, microwave power was 800 W, microwave time was 30 min, the ratio of xylan to AgNO3 was 50 mg: 0.13 mmol, and ammonia concentration was 2%. In addition, the AgNPs were collected via highspeed centrifugal separation, and the supernatant was tested by HPAEC, GPC, FT-IR, and NMR. By comparing the structure of xylan before and after the reaction, the reaction mechanism was discussed. It was noted that the xylan-AgNPs composites showed high selectivity and sensitivity for Hg2+ detection. The other 15 metal ions used had no obvious effect on the detection of Hg2+, and the limit of detection (LOD) was 4.6 nM, which is lower than the allowed maximum level of 30 nM for drinking water by WHO. In addition, the xylan-AgNPs composites can be applied for Hg2+ detection in real water samples. This study provides a novel way for the high-value utilization of a rich biomass resource, and a green method for the synthesis of AgNPs for the selective and sensitive detection of harmful heavy metals

One-pot green synthesis and antimicrobial activity of exfoliated Ag NP-loaded quaternized chitosan/clay nanocomposites

A rapid and green method is reported to synthesize silver nanoparticles (Ag NPs) and simultaneously achieve exfoliated chitosan/clay nanocomposite under microwave irradiation, in which quaternized chitosan (QCS), montmorillonite (MMT) and Gemini surfactant were used as reducing and stabilizing agents, other chemical reductants were not involved. XRD, FT-IR, NMR, TEM and AAS were performed to characterize Ag NP-loaded QCS/clay nanocomposites. The results indicated that the formation of spherical Ag NPs (about 26 nm) were mainly associated with reduction effect of QCS, surfactant and clay hardly participate in the synthesis of Ag NP, but benefited its formation. During the formation of Ag NPs, the layers of clay were peeled, the exfoliated Ag NP-loaded QCS/clay nanocomposites were obtained. Moreover, Ag NP-loaded QCS/clay nanocomposites showed excellent antimicrobial activity. The lowest minimum inhibition concentration against microorganisms was 0.00001 wt%. At last, the antimicrobial mechanism was evaluated by TEM and SEM micrographs

Prediction of thin shoal-facies reservoirs in the carbonate platform interior: A case from the Cambrian Xixiangchi Group of the Weiyuan area, Sichuan Basin

This paper presents a geological prediction method of thin shoal facies reservoir through the analysis of shoal facies reservoir's genetic mechanism of the Middle-Upper Cambrian Xixiangchi Group in the Weiyuan area, Sichuan Basin. The development of shoal facies reservoirs is controlled by shoal thickness. Both sedimentary rates and scales of the shoal are closely related to microtopographic highs, which can develop inheritably for a long time under a stable tectonic background. So we present a prediction method that depositional microtopographic highs and shoal reservoirs' development probability can be portrayed by the thickness variation of isochronal geological bodies, which mainly composed of grain stone formed in a short time. Based on it, a prediction model was built for thin shoal facies reservoirs of the Middle-Upper Cambrian Xixiangchi Group, where useful geological data are extremely poor. The method was used to predict the distribution of shoal facies reservoirs within the research area. Later drilling showed that the prediction is consistent with the drilling result. This study can provide reference to the exploration of shoal facies reservoirs. Key words: carbonate platform, shoal, thin reservoir, prediction method, Cambrian Xixiangchi Grou

Multi-objective optimization design of a connection frame in macro-micro motion platform

10.1016/j.asoc.2015.03.044Applied Soft Computing32369-38