Effect of polyhydroxy-terminated PAMAM dendrimer on dentin matrix metalloproteinases within the hybrid layers.

BACKGROUND: Intrafibrillar remineralization within the hybrid layers (HLs) has recently attracted extensive attention in achieving durable resin-dentin bonds. The polyhydroxy-terminated poly(amidoamine) dendrimer (PAMAM-OH) at fourth generation becomes a desirable candidate to induce intrafibrillar remineralization to protect exposed collagen fibrils within HLs based on the size exclusion effect of fibrillar collagen. However, the remineralization process in vivo is time-consuming, during which the exposed collagen fibrils are vulnerable to enzymatic degradation, resulting in unsatisfactory remineralization. Thereby, if PAMAM-OH itself possesses concomitant anti-proteolytic activity during the induction of remineralization, it would be very beneficial to obtain satisfactory remineralization. METHODS: Binding capacity tests using adsorption isotherm and confocal laser scanning microscopy (CLSM) were performed to assess if the PAMAM-OH had adsorption capacity on dentin. Anti-proteolytic testings were detected by MMPs assay kit, in-situ zymography and ICTP assay. Adhesive infiltration of resin-dentin interface and tensile bond strength before and after thermomechanical cycling were implemented to assess if the PAMAM-OH adversely affected resin-dentin bonds. RESULTS: Anti-proteolytic testings performed using MMPs assay kit, in-situ zymography and ICTP assay indicated that PAMAM-OH inhibited exogenous soluble MMP-9 as well as had inhibitory effect on the endogenous proteases. Adhesive infiltration of resin-dentin interface and tensile bond strength before and after thermomechanical cycling were implemented to indicate that the PAMAM-OH pretreatment had no adverse effects on immediate dentin bonding and prolonged the durability of resin-dentin bonds. CONCLUSIONS: PAMAM-OH possesses anti-proteolytic activity and prevents exposed collagen fibrils within HLs from degradation, which lays the foundation for the satisfactory intrafibrillar remineralization induced by PAMAM-OH within HLs to achieve durable resin-dentin bonds in the next work.

The environmental benefit of Beijing-Tianjin-Hebei coal banning area for North China.

In order to achieve the targets specified in the Action Plan for Air Pollution Prevention and Control (APAPPC), a limited coal banning area (10,000 km2) was designated in the heavily polluted Beijing-Tianjin-Hebei region (BTH) for the first time in 2017. PM2.5 and elements were sampled by the network of BTH to evaluate the effectiveness of this policy. This study found that the fine days with PM2.5 < 75 µg m-3 accounted for 74.3% in the autumn and winter of 2017, which was significantly higher than that in 2016 (43%). The heavily polluted days (PM2.5 > 150 µg m-3) also decreased from 32.2% in 2016 to 4.9% in 2017. Arsenic (As) is an important tracer in coal consumption, which can be used to reflect the influence of the establishment of coal banning areas on north China. The cluster analysis of air mass forward trajectory identified that the number of polluted trajectories with PM2.5 and As in 2017 decreased by 47.6% and 49.7%, respectively. Under the implementation of the coal banning policy, the weighted concentration of PM2.5 and As decreased by 94.2 µg m-3 and 5.1 ng m-3 in the coal banning area, 60.9 µg m-3 and 3.4 ng m-3 in the no coal banning area in BTH, respectively. The influence of weighted concentration of PM2.5 and As in coal banning area on North China were 1.6-49.2 µg m-3 and 0.15-2.8 ng m-3, respectively, which was 38.8% and 29.7% lower than 2016. In coal banning area, BTH and other parts of North China, the reduction of the weight concentration of PM2.5 in 2017 accounted for 41.4%, 26.8% and 31.8% of the total reduction, respectively, so was the As in 39%, 26.3% and 34.6%, indicating that setting up a coal banning area scientifically in limited areas can produce remarkable regional benefit.

Effect of Cavity Cleanser With Long-Term Antibacterial and Anti-Proteolytic Activities on Resin-Dentin Bond Stability.

Objective: Secondary caries caused by oral microbiome dysbiosis and hybrid layer degradation are two important contributors to the poor resin-dentin bond durability. Cavity cleansers with long-term antimicrobial and anti-proteolytic activities are in demand for eliminating bacteria-induced secondary caries and preventing hybrid layers from degradation. The objectives of the present study were to examine the long-term antimicrobial effect and anti-proteolytic potential of poly(amidoamine) dendrimers with amino terminal groups (PAMAM-NH2) cavity cleanser. Methods: Adsorption tests by attenuated total reflectance-infrared (ATR-IR) spectroscopy and confocal laser scanning microscopy (CLSM) were first performed to evaluate whether the PAMAM-NH2 cavity cleanser had binding capacity to dentin surface to fulfill its relatively long-term antimicrobial and anti-proteolytic effects. For antibacterial testing, Streptococcus mutans, Actinomyces naeslundii, and Enterococcus faecalis were grown on dentin surfaces, prior to the application of cavity cleanser. Colony-forming unit (CFU) counts and live/dead bacterial staining were performed to assess antibacterial effects. Gelatinolytic activity within the hybrid layers was directly detected by in situ zymography. Adhesive permeability of bonded interface and microtensile bond strength were employed to assess whether the PAMAM-NH2 cavity cleanser adversely affected resin-dentin bonding. Finally, the cytotoxicity of PAMAM-NH2 was evaluated by the Cell Counting Kit-8 (CCK-8) assay. Results: Adsorption tests demonstrated that the binding capacity of PAMAM-NH2 on dentin surface was much stronger than that of 2% chlorhexidine (CHX) because its binding was strong enough to resist phosphate-buffered saline (PBS) washing. Antibacterial testing indicated that PAMAM-NH2 significantly inhibited bacteria grown on the dentin discs as compared with the control group (p < 0.05), which was comparable with the antibacterial activity of 2% CHX (p > 0.05). Hybrid layers conditioned with PAMAM-NH2 showed significant decrease in gelatin activity as compared with the control group. Furthermore, PAMAM-NH2 pretreatment did not adversely affect resin-dentin bonding because it did not decrease adhesive permeability and microtensile strength. CCK-8 assay showed that PAMAM-NH2 had low cytotoxicity on human dental pulp cells (HDPCs) and L929. Conclusions: PAMAM-NH2 cavity cleanser developed in this study could provide simultaneous long-term antimicrobial and anti-proteolytic activities for eliminating secondary caries that result from a dysbiosis in the oral microbiome and for preventing hybrid layers from degradation due to its good binding capacity to dentin collagen matrix, which are crucial for the maintenance of resin-dentin bond durability.

MICA enhances sensitivity to cisplatin in patients with extensive small cell lung cancer via downregulation of ABCG2.

Immunotherapy utilizing natural killer cell-activated receptor natural-killer group-2 member D ligands (NKG2DLs) has had preclinical success in the treatment of small cell lung cancer. The present study aimed to investigate the association between NKG2Ls and chemoresistance. The mRNA expression of six NKG2DLs associated with progression-free survival time (PFS) and first-line chemotherapy were assessed in the present study. Major histocompatibility complex class I polypeptide-related sequence A (MICA)-overexpressing NCI-H446 cell line was constructed, and the mRNA expression levels of 11 genes associated with chemotherapy sensitivity were determined. The results demonstrated that MICA was positively and significantly associated with PFS. Furthermore, MICA expression was 1.6 times higher in patients with prolonged PFS compared with the rapid chemoresistance group. ATP binding cassette subfamily G member 2 (ABCG2) mRNA expression was associated with chemotherapy resistance and significantly downregulated in the cell line overexpressing MICA. Moreover, following addition of nicardipine (an ABCG2 inhibitor), chemotherapeutic sensitivity increased in the MICA-overexpressing cell line. Taken together, the results of the present study suggested that MICA may enhance the chemosensitivity of patients with extensive small cell lung cancer by downregulating ABCG2.

Impact of the coal banning zone on visibility in the Beijing-Tianjin-Hebei region.

The Beijing-Tianjin-Hebei (BTH) region, which has the most severe air pollution in China, built a 10,000 km2 coal banning zone for pollution control in 2017. In this study, to evaluate the impact of banning coal zone on visibility (VIS), a chemical composition analysis, a chemical mass closure and the revised IMPROVE algorithm were applied to estimate the chemical components and lighting extinction coefficients (bext) of the fine particulate matter (PM2.5) collected at three urban sites (Beijing (BJ), Tianjin (TJ) and Shijiazhuang (SJZ)) and a regional background site (Xinglong (XL)) during autumn and winter of 2016-2017. Compared to measurements from 2016, the average PM2.5 from 2017 decreased by 44 µg m-3 (BJ), 37 µg m-3 (TJ), 69 µg m-3 (SJZ) and 10 µg m-3 (XL), respectively, accompanied by an improved VIS (3.2-4.6 km). The degradation of VIS caused by atmospheric aerosol is due to the light extinction. The bext clearly decreased by 58%, 51%, 56% and 54% at BJ, TJ, SJZ and XL, respectively. However, the reductions/improvements were more significant in winter than those in autumn, especially at BJ and TJ located in the coal banning zone. The decline (improvement) in PM2.5 (VIS) was 16%-37% (15%-27%) in autumn but 29%-60% (21%-83%) in winter. The reductions in SO42- (Cl-) in winter were 2.8 (3.2) and 7.4 (16.4) times larger than those in autumn at BJ and TJ, respectively. Reductions in ammonium sulfate, one of the main species of PM2.5 caused by coal burning, were particularly pronounced at three urban sites in winter (59%-68%). In addition, the reductions in bext in winter were 2.3 (BJ), 339.4 (TJ), 1.9 (SJZ) and 0.4 (XL) times larger than those in autumn. The results reveal that banning coal zone has a marked effect on controlling pollution in the BTH, especially in winter (scattering aerosol sulfate).

Depression induces poor prognosis associates with the down-regulation brain derived neurotrophic factor of serum in advanced small cell lung cancer.

Patients with lung cancer often experience a state of depression, and these conditions may severely affect their quality of life (QoL) and prescription compliance. The current study was conducted to delineate the complex links between depression and the prognosis of patients with small cell lung cancer (SCLC) and the underlying mechanism was also explored.186 patients who received platinum-based chemotherapy for newly diagnosed stage III or stage IV SCLC were enrolled. The Self-Rating Depression Scale (SDS) questionnaire was completed the day before the start of chemotherapy to assess the depression status of the patients. Patients with stage IV SCLC or lower BMI have higher depression scores. In terms of the adverse effects of chemotherapy, depression severely decreases patient tolerance to chemotherapy and their QoL score (R2 = 0.2385) and is also associated with severe vomiting (P < 0.001), leukopenia (R2 = 0.2332), and prolonged hospital stay (R2 = 0.1961). More importantly, severe depression reduces the PFS (R2 = 0.1943) and OS (P < 0.01) of the patients. We found that patients with severe depression displayed a downregulated level of serum BDNF and that the level of serum BDNF was highly correlated with the OS of the patients (R2 = 0.2292). Using the MTT cell viability assay in vitro, we observed that cotreatment with BDNF clearly enhanced the chemosensitivity of NCI-H69 tumor cells to Cisplatin and induced the downregulation of ABCG2.Based on this evidence, it appears that a relationship does exist between depression and prognosis in SCLC and that the mechanism by which depression affects prognosis is achieved via the downregulation of BDNF expression.

Cellular retinoic acid binding protein 2 inhibits osteogenic differentiation by modulating LIMK1 in C2C12 cells.

Cellular retinoic acid binding protein 2 (CRABP2) is essential for myoblast differentiation, however, little is known about its role in osteogenic differentiation. This study mainly aims to explore the biological functions and the underlying molecular mechanisms of CRABP2 in osteogenesis. Using quantitative polymerase chain reaction and western blot assays, we found that the expression of CRABP2 at both mRNA and protein levels were downregulated during osteogenesis. Furthermore, CRABP2 knockdown displayed significant changes in the cell phenotype and the actin filaments (F-actin) polymerization in C2C12 cells treated with BMP2. Moreover, the western blotting of osteogenic differentiation biomarkers, alkaline phosphatase (ALP) staining and Alizarin red staining showed that CRABP2 dramatically inhibited osteogenic differentiation. The following investigation of molecular mechanisms implicated that CARBP2 specifically interacted with LIMK1, a key factor in acin cytoskeletal rearrangements in osteogenesis, to interrupt its activity and stability in an ubiquitin-proteasome pathway to prevent C2C12 cells from osteogenic differentiation in response to BMP2. Above all, our data suggest a novel function of CRABP2 in regulating actin remodeling and osteogenic differentiation via LIMK1, thus presenting a possible molecular target for promoting the osteogenic differentiation in bone degenerative diseases.

Cholesterol reduces the sensitivity to platinum-based chemotherapy via upregulating ABCG2 in lung adenocarcinoma.

Inoperable lung adenocarcinoma is currently treated with platinum-based chemotherapy. However, the effectiveness of these chemotherapeutic agents is not the same for all patients. Patients either show quick chemoresistance (QCR) or delayed chemoresistance (DCR), which are defined by 87 and 242 days of progression-free survival (PFS) after initial platinum-based treatment, respectively. We found that QCR patients displayed an elevated level of serum cholesterol and that their tumors showed upregulated ABCG2 expression. We propose that chemoresistance may be attributed to cholesterol-induced ABCG2 expression and hypothesize that blocking ABCG2 may increase the efficacy of platinum-based chemotherapeutic agents. Using the MTT cell viability assay, we observed that cotreatment with ABCG2 blocker Nicardipine and platinum-based drugs Cisplatin, Oxaliplatin or Carboplatin significantly decreased cell viability of tumor cells. Importantly, our results also showed that incubating cells with cholesterol prior to chemotherapy treatment or cotreatment increased cell viability of tumor cells relative to the controls.