Investigation of dissimilatory nitrate reduction to ammonium (DNRA) in urban river network along the Huangpu River, China: rates, abundances, and microbial communities.

Dissimilatory nitrate reduction to ammonium (DNRA) is an essential intermediate step in the nitrogen cycle, and different sediment physicochemical properties can affect the DNRA process. But the detailed research on the environmental nitrogen cycling in urban river networks based on DNRA communities and the functional gene nrfA is lacking. In this study, the flow line of the Huangpu River in Shanghai was analyzed using isotope tracer, quantitative real-time PCR, and high-throughput sequencing techniques to evaluate the role of DNRA on the stability of the river network and marine. The significant positive correlation between the rate of DNRA and sediment organic carbon was identified. At the genus level, Anaeromyxobacter is the most dominant. Notably, both heterotrophic and autotrophic DNRA species were discovered. This study added diversity to the scope of urban freshwater river network ecosystem studies by investigating the distribution of DNRA bacteria along the Huangpu River. It provided new insights into the biological nitrogen cycle of typical urban inland rivers in eastern China.

Silk fibroin/reduced graphene oxide composite mats with enhanced mechanical properties and conductivity for tissue engineering.

In this work, we described a green and simple approach for fabricating regenerated silk fibroin (RSF)/reduced graphene oxide (RGO) fibrous mats by reducing GO in the RSF/GO mats through hydrothermal treatment. As a comparison, RSF mat incorporated with graphene (Gr) was fabricated by solution mixing method. Results showed that the reduction of GO in the mats did take place during hydrothermal treatment. An increase in the crystallinity of the mats was induced by hydrothermal treatment. The maximum Young's modulus of RSF/RGO mats reached (122.7 ± 3.1) MPa, which was at least 9-fold higher than RSF mats. As the mass ratio of RGO/RSF was 1.5/100, the average sheet resistance of RSF/RGO mats reached (1.2 ± 0.1)×108 Ω/sq, which was better and more stable than that of RSF/Gr mats. Furthermore, cellular tests and antibacterial tests demonstrated that RSF/RGO mats possessed better biocompatibility and antibacterial property in comparison with RSF mats incorporated with GO or Gr. Thus, the RSF/RGO mats could be a good candidate for tissue engineering applications.

Analysis of immune-related signatures of colorectal cancer identifying two different immune phenotypes: Evidence for immune checkpoint inhibitor therapy.

Immune checkpoint inhibitor (ICI) therapy has revolutionized the treatment of numerous types of cancer, including colorectal cancer (CRC). Patients with CRC and deficient mismatch repair or high microsatellite instability could benefit from ICI treatment, although the response rate of most patients is low. Therefore, the immune subtyping of patients with CRC is required in order to determine the subtypes suitable for ICI treatment. The present study used a cohort of patients with CRC from The Cancer Genome Atlas (TCGA) to perform molecular subtyping, with results validated in three CRC cohorts from the Gene Expression Omnibus. Non-negative matrix factorization was used to achieve consensus molecular subtyping. The tumor immune dysfunction and exclusion algorithm was used to predict potential ICI therapy responses and gene set enrichment analysis was performed to define different pathways associated with the immune response. Two distinct subtypes of CRC were finally identified in TCGA cohorts, which were characterized as significantly different prognostic subtypes (low-risk and high-risk subtypes). Higher expression of programmed death-ligand 1, higher proportion of tumor-infiltrating lymphocytes and tumor mutation burden were significantly enriched in the low-risk subtype. Further pathway analysis revealed that the low-risk subtype was associated with immune response activation and signaling pathways involved in 'antigen processing and presentation'. Three independent CRC cohorts were used to validate the above findings. In summary, two clinical CRC subtypes were identified, which are characterized by significantly different survival outcomes and immune infiltration patterns. The findings of the present study suggest that ICI treatment may be more effective in the low-risk CRC subtype.

Peripheral Blood miR-451 May Serve as a Biomarker of Ischemic Stroke.

BACKGROUND: The current study aims to investigate the correlation between the expression level of miR-451 in peripheral blood and the risk of ischemic stroke, and its feasibility as a biomarker of ischemic stroke. METHODS: Three hundred and two cases of ischemic stroke diagnosed in Qianfoshan Hospital Affiliated to Shandong University from April 2017 to Dec 2017 and 302 cases matched for age and gender were selected from routine health examination subjects. Real-time quantitative PCR was used to detect the expression of microRNA in peripheral blood. Receiver operating curve (ROC) was used to analyze whether miR-451 could be used as a basis for judging ischemic stroke. RESULTS: The expression level of miR-451 in peripheral blood of patients with ischemic stroke was higher than that of the control group (p < 0.05). ROC analysis demonstrated that peripheral blood miR-451 could screen ischemic stroke patients from healthy controls, with the AUC of 0.912. In addition, the expression level of miR-451 was negatively correlated with the number of platelets and platelet hematocrit (p < 0.05). CONCLUSIONS: There is a significant correlation between the expression level of miR-451 in peripheral blood and the occurrence of ischemic stroke. miR-451 is expected to be a biomarker of ischemic stroke.

Bacterial cellulose nanofibers promote stress and fidelity of 3D-printed silk based hydrogel scaffold with hierarchical pores.

One of the latest trends in the regenerative medicine is the development of 3D-printing hydrogel scaffolds with biomimetic structures for tissue regeneration and organ reconstruction. However, it has been practically difficult to achieve a highly biomimetic hydrogel scaffolds with proper mechanical properties matching the natural tissue. Here, bacterial cellulose nanofibers (BCNFs) were applied to improve the structural resolution and enhance mechanical properties of silk fibroin (SF)/gelatin composite hydrogel scaffolds. The SF-based hydrogel scaffolds with hierarchical pores were fabricated via 3D-printing followed by lyophilization. Results showed that the tensile strength of printed sample increased significantly with the addition of BCNFs in the bioink. Large pores and micropores in the scaffolds were achieved by designing printing pattern and lyophilization after extrusion. The pores ranging from 10 to 20 µm inside the printed filaments served as host for cellular infiltration, while the pores with a diameter from 300 to 600 µm circled by printed filaments ensured sufficient nutrient supply. These 3D-printed composite scaffolds with remarkable mechanical properties and hierarchical pore structures are promising for further tissue engineering applications.

NiO/M-Sil-1 Catalysts by In-Situ Coupled Assembly of Metal Oxides and Silicalite-1 Zeolite with Improved Stability for Methane Steam Reforming Reaction.

NiO/M-Sil-1 catalysts were successfully prepared by in situ coupled assembly of metal oxides and silicalite-1 zeolite. All the NiO/M-Sil-1 samples had high surface areas, which resulted from the uniform dispersion and small particle size of the active components. Zr-doped Ni/M-Sil-1 exhibited a 20% lower NiO average particle size and a 6% lower NiO reduction temperature compared with those of the nondoped catalysts. Consequently, the Ni/Zr-Sil-1 catalyst exhibited the best catalytic performance, with the CO selectivity in methane steam reforming drastically decreasing by 11.5%, H2 concentration in the reformed gas increasing by about 1.7%, and H2/CO molar ratio increasing by 0.8. Moreover, its initial methane conversion efficiency was 99.8% and was retained by 97.7% after a 578 h continuous stability test. Furthermore, the traditional water/carbon molar ratio in methane steam reforming reduced from 3-5 to 2, and the methane conversion remained above 98.1%, with a high thermal stability that substantially increased the energy efficiency.

Super-strong and Intrinsically Fluorescent Silkworm Silk from Carbon Nanodots Feeding.

Fluorescent silk is fundamentally important for the development of future tissue engineering scaffolds. Despite great progress in the preparation of a variety of colored silks, fluorescent silk with enhanced mechanical properties has yet to be explored. In this study, we report on the fabrication of intrinsically super-strong fluorescent silk by feeding Bombyx mori silkworm carbon nanodots (CNDs). The CNDs were incorporated into silk fibroin, hindering the conformation transformation, confining crystallization, and inducing orientation of mesophase. The resultant silk exhibited super-strong mechanical properties with breaking strength of 521.9 ± 82.7 MPa and breaking elongation of 19.2 ± 4.3%, improvements of 55.1% and 53.6%, respectively, in comparison with regular silk. The CNDs-reinforced silk displayed intrinsic blue fluorescence when exposed to 405 nm laser and exhibited no cytotoxic effect on cells, suggesting that multi-functional silks would be potentially useful in bioimaging and other applications.

Angiogenesis Potential of Bladder Acellular Matrix Hydrogel by Compounding Endothelial Cells.

Rapid vascularization is very important in tissue engineering. Bladder acellular matrix (BAM) with inherent bioactive factors, a natural extracellular matrix (ECM) derived biomaterial, has been widely used as a scaffold to facilitate the repair and reconstruction of urinary tissues. However, the application of the traditional BAM scaffold has been limited due to the dense structure. To investigate the angiogenic potential of BAM, BAM hydrogels with tailored porous structures were prepared in this study by tuning BAM concentrations (4, 6, and 8 mg/mL). The 6 mg/mL BAM hydrogel was loaded with porcine iliac endothelial cells (PIECs), and their angiogenic potential was analyzed in vitro and in vivo. The mechanical strength and gelation speed of the BAM hydrogels increased, while their pore size decreased as concentration increased. Commercially available collagen hydrogel (2.5 mg/mL) showed weaker mechanical properties than BAM hydrogels but similar gelation speed and pore size as 6 mg/mL BAM hydrogel. To ensure a similar three-dimensional microenvironment for the PIECs, 6 mg/mL BAM and collagen hydrogels were selected for the in vitro and in vivo experiments. A significantly higher density of viable, fusiform PIECs of average length ∼50 µm was observed in the BAM hydrogel, while those inside the collagen hydrogel were spherical and ∼30 µm long. In addition, the PIECs/BAM hydrogel resulted in significantly higher revascularization compared with the PIECs/collagen and unloaded BAM hydrogels. The higher angiogenic potential of the PIECs/BAM hydrogel is due to the growth factors that promote PIEC proliferation and therefore vascularization.

Silk scaffolds with gradient pore structure and improved cell infiltration performance.

Electrospun scaffold with three-dimensional (3D) geometry and appropriate pore structure is an important challenge to mimic natural tissues such as skin, cartilage, etc. In this work, 3D silk fibroin (SF) electrospun scaffolds with gradient pore size were prepared by combining multi-step electrospinning with low temperature (LTE) collecting. The LTE electrospun scaffolds achieved 3D macro-structure with large pore size. The effects of relative humidity (RH), collecting temperature on the morphology of the scaffolds were investigated by scanning electron microscopy and computed tomography. The pore size of the scaffolds was tailored by adjusting SF concentration, electric field, flow rate, needle gauge and collector temperature during electrospinning at 50% RH. L929 cell infiltration results of the scaffolds showed that conventional electrospun scaffolds with small pore size (average diameter 5.9 ±â€¯1.4 µm) restrained cell proliferation and infiltration. On the contrary, LTE electrospun scaffolds with medium pore size (average diameter 11.6 ±â€¯1.4 µm) improved cell proliferation obviously. Large pore size scaffolds (average diameter 37.2 ±â€¯12.9 µm) was beneficial to cell infiltration depth in the thickness direction of the scaffolds. The scaffolds, which were integrated with layers of small, medium and large pores, are promising in the repair of tissue with gradient pore structures.

Synthesis and evaluation of novel isoxazolyl chalcones as potential anticancer agents.

A series of novel isoxazolyl chalcones were synthesized and evaluated for their activities in vitro against four types of human non-small cell lung cancer cells, including H1792, H157, A549 and Calu-1 cells. The preliminary biological screening showed that compounds 5d and 5f-i exhibited significant cytotoxicity, particularly, compounds 5f and 5h were identified as the most potent anticancer agents with IC50 values 1.35-2.07 µM and 7.27-11.07 µM against H175, A549 and Calu-1 cell lines, respectively. Compounds 5f-i could induce apoptosis in A549 cells by death receptor 5 (DR5) mediated extrinsicpathways. The preliminary structure-activity relationship study showed that compounds bearing electron withdrawing groups (EWG) at the 2-position of the phenyl ring in Ar group were more effective than those with EWG at 4-position. These results further demonstrated that the scaffolds designed in this work might lead to the discovery of novel anti-lung cancer agents.

Synthesis, physical properties and cytotoxicity of stilbene-triazine derivatives containing amino acid groups as fluorescent whitening agents.

A series of novel stilbene-triazine derivatives containing amino acid groups were synthesized and screened to evaluate their cytotoxicity. The UV absorptions of the derivatives were in the range of 240-450 nm. The absorption peaks of the cis-isomers and trans-isomers were in 281-291 nm and 353-361 nm, respectively. Their fluorescence emission peaks of the derivatives were located in the range of 400-650 nm. The whiteness data indicated that all the stilbene-triazine-amino acid derivatives showed excellent whitening effect on cotton fiber compared to untreated cotton. The preliminary cytotoxicity of these derivatives on a mouse fibroblast cell line (L-929 cells) was also investigated. The results showed that the compounds (7a-h) were nontoxic to L-929 cells as fluorescent whitening agents.

A novel porcine acellular dermal matrix scaffold used in periodontal regeneration.

Regeneration of periodontal tissue is the most promising method for restoring periodontal structures. To find a suitable bioactive three-dimensional scaffold promoting cell proliferation and differentiation is critical in periodontal tissue engineering. The objective of this study was to evaluate the biocompatibility of a novel porcine acellular dermal matrix as periodontal tissue scaffolds both in vitro and in vivo. The scaffolds in this study were purified porcine acellular dermal matrix (PADM) and hydroxyapatite-treated PADM (HA-PADM). The biodegradation patterns of the scaffolds were evaluated in vitro. The biocompatibility of the scaffolds in vivo was assessed by implanting them into the sacrospinal muscle of 20 New Zealand white rabbits. The hPDL cells were cultured with PADM or HA-PADM scaffolds for 3, 7, 14, 21 and 28 days. Cell viability assay, scanning electron microscopy (SEM), hematoxylin and eosin (H&E) staining, immunohistochemistry and confocal microscopy were used to evaluate the biocompatibility of the scaffolds. In vitro, both PADM and HA-PADM scaffolds displayed appropriate biodegradation pattern, and also, demonstrated favorable tissue compatibility without tissue necrosis, fibrosis and other abnormal response. The absorbance readings of the WST-1 assay were increased with the time course, suggesting the cell proliferation in the scaffolds. The hPDL cells attaching, spreading and morphology on the surface of the scaffold were visualized by SEM, H&E staining, immnuohistochemistry and confocal microscopy, demonstrated that hPDL cells were able to grow into the HA-PADM scaffolds and the amount of cells were growing up in the course of time. This study proved that HA-PADM scaffold had good biocompatibility in animals in vivo and appropriate biodegrading characteristics in vitro. The hPDL cells were able to proliferate and migrate into the scaffold. These observations may suggest that HA-PADM scaffold is a potential cell carrier for periodontal tissue regeneration.

Human periodontal ligament cells reaction on a novel hydroxyapatite-collagen scaffold.

BACKGROUND: Periodontal tissue regeneration presents a highly promising method for restoring periodontal structures. The development of a suitable bioactive scaffold that promotes cell proliferation and differentiation is critical in periodontal tissue engineering. The aim of this study was to evaluate the biocompatibility of a novel 3-dimensional hydroxyapatite-collagen scaffold with human periodontal ligament (hPDL) cell culture. METHODS: The scaffold was produced from a natural collagen matrix - purified porcine acellular dermal matrix (PADM), which was then treated with hydroxyapatite (HA) through a biomimetic chemical process to obtain hydroxyapatite-porcine acellular dermal matrix (HA-PADM) scaffold. The hPDL cells were cultured with HA-PADM scaffolds for 1, 3, 6, 14, and 28 days. The cell viability assay, scanning electron microscopy (SEM), hematoxylin and eosin (H&E) staining, immunohistochemistry, and confocal microscopy were employed in different time points to evaluate the biocompatibility of the scaffolds with hPDL cells. RESULTS: The cell viability assay (WST-1 test) verified cell proliferation on the HA-PADM scaffolds. The SEM study showed unique morphology of hPDL cells, which attach and spread on the surface of the scaffolds. The H&E staining, immunohistochemistry, and confocal microscopy demonstrated that hPDL cells were able to grow into the HA-PADM scaffolds and maintain viability after prolonged culture. CONCLUSIONS: This study proved that HA-PADM scaffold is -biocompatible for hPDL cells. The cells were able to proliferate and migrate into the scaffold. These observations suggest that HA-PADM is a potential cell carrier for periodontal tissue regeneration.

In vitro biomimetic construction of hydroxyapatite-porcine acellular dermal matrix composite scaffold for MC3T3-E1 preosteoblast culture.

The application of porous hydroxyapatite-collagen (HAp-Collagen) as a bone tissue engineering scaffold is hindered by two main problems: its high cost and low initial strength. As a native 3-dimenssional collagen framework, purified porcine acellular dermal matrix (PADM) has been successfully used as a skin tissue engineering scaffold. Here we report its application as a matrix for the preparation of HAp to produce a bone tissue scaffold through a biomimetic chemical process. The HAp-PADM scaffold has two-level pore structure, with large channels (∼100 µm in diameter) inherited from the purified PADM microstructure and small pores (<100 nm in diameter) formed by self-assembled HAp on the channel surfaces. The obtained HAp-PADM scaffold (S15D) has a compressive elastic modulus as high as 600 kPa. The presence of HAp in sample S15D reduces the degradation rate of PADM in collagenase solution at 37°C. After 7 day culture of MC3T3-E1 pre-osteroblasts, MTT data show no statistically significant difference on pure PADM framework and HAp-PADM scaffold (p > 0.05). Because of its high strength and nontoxicity, its simple preparation method, and designable and tailorable properties, the HAp-PADM scaffold is expected to have great potential applications in medical treatment of bone defects.

Two-step modification of poly(D, L-lactic acid) by ethylenediamine-maleic anhydride.

Poly(lactic acid) (PLA) was modified by maleic anhydride (MAH), then the resultant MAH modified PLA (MPLA) was acylated with ethylenediamine (EDA), so EDA-MAH modified PLA (EMPLA) was prepared. The results of DSC, FT-IR and NMR testified that MAH and EAD were successfully introduced into the original polymer. The hydrophilicity of EMPLA was considerably increased compared with that of PLA. The degradation experiment showed that the introduction of EDA into the original polymer could neutralize the carboxyl end groups of the degradation products. The results of SEM and MTT of rat osteoblasts cultured in vitro showed that the cytocompatibility and cell adhesion of the modified materials were significantly increased compared with the original polymer, especially EMPLA; the number of cells were obviously increased and cells attached firmly to the material; these were ascribed to the EDA neutralizing the carboxyl end groups of the degradation products.