Active control of terahertz waves based on hybrid VO2 periodic corrugated waveguides.

We describe a method for the active control of terahertz (THz) waves using hybrid vanadium dioxide (VO2) periodic corrugated waveguide. Unlike liquid crystals, graphene and semiconductors and other active materials, VO2 exhibits a unique insulator-metal transition characteristic by the electric fields, optical, and thermal pumps, resulting in five orders of magnitude changes in its conductivity. Our waveguide consists of two gold coated plates with the VO2-embedded periodic grooves, which are placed in parallel with the grooves face to face. Simulations show that this waveguide can realize mode switching by changing the conductivity of the embedded VO2 pads, whose mechanism is attributed to the local resonance induced by defect mode. Such a VO2-embedded hybrid THz waveguide is favorable in practical applications such as THz modulators, sensors and optical switches, and provides an innovative technique for manipulating THz waves.

The potential influence of long non-coding RNA PRKG1-AS1 on oral squamous cell carcinoma: A comprehensive study based on bioinformatics and in vitro validation.

BACKGROUND: Oral squamous cell carcinoma (OSCC) is one of the most frequent malignancies in oral cancer. Herein, we aimed to investigate the influence of lncRNA protein kinase cGMP-dependent type I-Antisense RNA 1 (PRKG1-AS1) in OSCC progression. METHODS: Basing on the data acquired from TCGA database, the expression and prognostic value of PRKG1-AS1 in OSCC patients were assessed. The expression of PRKG1-AS1 in OSCC cells was determined by quantitative real-time polymerase chain reaction (qRT-PCR). Cell growth was evaluated by Cell Counting Kit-8 (CCK8) and colony-forming assays. Transwell assay was employed to test cell invasion and migration. The protein expression of epithelial-mesenchymal transition (EMT)-related markers was detected by Western blotting. RESULTS: The consequences displayed that PRKG1-AS1 was highly expressed in OSCC tissues and high expression of PRKG1-AS1 predicted poor outcomes. The expression of PRKG1-AS1 was higher in CAL27, SCC-9, and SCC-4 than that in normal human oral keratinocytes (NHOK). The results of biological experiments showed that deficiency of PRKG1-AS1 suppressed cell growth, invasion, and migration in CAL27 cells, and over-expression of PRKG1-AS1 accelerated cell growth, invasion, and migration in SCC-4 cells. Finally, silencing of PRKG1-AS1 obviously facilitated the protein expression levels of E-cadherin and reduced levels of N-cadherin, Vimentin, and Snail in CAL27 cells whereas over-expression of PRKG1-AS1 led to opposite results in SCC-4 cells. CONCLUSION: These outcomes indicated that PRKG1-AS1 functioned as a facilitator in OSCC cell growth, migration, and invasion, which all might be achieved by regulating EMT.

ClpP affects biofilm formation of Streptococcus mutans differently in the presence of cariogenic carbohydrates through regulating gtfBC and ftf.

The abilities to form biofilms on teeth surface and to metabolize a wide range of carbohydrates are key virulence attributes of Streptococcus mutans. ClpP has been proved to play an important role in biofilm development in streptococci. Here we demonstrated that ClpP was involved in biofilm formation of S. mutans. ClpP inactivation resulted in enhanced biofilm formation or initial cell adherence in broth supplemented with sucrose, while reduced in broth supplemented with glucose or fructose. Our results also indicated that the enhanced capacities of biofilm formation and initial cell adherence were achieved through regulating the expression of a number of extracellular sucrose-metabolizing enzymes, such as glucosyltransferases (GTFB and GTFC) at early-exponential growth phase and fructosyltransferase at late-exponential growth phase in the presence of sucrose.

Aerobic biodegradation of trichloroethylene and phenol co-contaminants in groundwater by a bacterial community using hydrogen peroxide as the sole oxygen source.

Trichloroethylene (TCE) and phenol were often found together as co-contaminants in the groundwater of industrial contaminated sites. An effective method to remove TCE was aerobic biodegradation by co-metabolism using phenol as growth substrates. However, the aerobic biodegradation process was easily limited by low concentration of dissolved oxygen (DO) in groundwater, and DO was improved by air blast technique with difficulty. This study enriched a bacterial community using hydrogen peroxide (H2O2) as the sole oxygen source to aerobically degrade TCE by co-metabolism with phenol in groundwater. The enriched cultures were acclimatized to 2-8 mM H2O2 which induced catalase, superoxide dismutase and peroxidase to decompose H2O2 to release O2 and reduce the toxicity. The bacterial community could degrade 120 mg/L TCE within 12 days by using 8 mM H2O2 as the optimum concentration, and the TCE degradation efficiency reached up to 80.6%. 16S rRNA gene cloning and sequencing showed that Bordetella, Stenotrophomonas sp., Sinorhizobium sp., Variovorax sp. and Sphingobium sp. were the dominant species in the enrichments, which were clustered in three phyla: Alphaproteobacteria, Betaproteobacteria and Gammaproteobacteria. Polymerase chain reaction detection proved that phenol hydroxylase (Lph) gene was involved in the co-metabolic degradation of phenol and TCE, which indicated that hydroxylase might catalyse the epoxidation of TCE to form the unstable molecule TCE-epoxide. The findings are significant for understanding the mechanism of biodegradation of TCE and phenol co-contamination and helpful for the potential applications of an aerobic bioremediation in situ the contaminated sites.

Contribution of ClpP to stress tolerance and virulence properties of Streptococcus mutans.

Abilities to tolerate environmental stresses and to form biofilms on teeth surface are key virulence attributes of Streptococcus mutans, the primary causative agent of human dental caries. ClpP, the chief intracellular protease of S. mutans, along with ATPases degrades altered proteins that might be toxic for bacteria, and thus plays important roles in stress response. To further understand the roles of ClpP in stress response of S. mutans, a ClpP deficient strain was constructed and used for general stress tolerance, autolysis, mutacins production, and virulence assays. Here, we demonstrated that inactivation of ClpP in S. mutans resulted in a sensitive phenotype to several environmental stresses, including acid, cold, thermal, and oxidative stresses. The ClpP deficient strain displayed slow growth rates, poor growth yields, formation of long chains, increased clumping in broth, and reduced capacity to form biofilms in presence of glucose. Mutacins production and autolysis of S. mutans were also impaired by mutation of clpP. Animals study showed that clpP mutation increased virulence of S. mutans but not significant. However, enhanced abilities to survive lethal acid and to form biofilm in sucrose were observed in ClpP deficient strain. Our findings revealed a broad impact of ClpP on several virulence properties of S. mutans and highlighted the relevance of ClpP proteolysis with progression of diseases caused by S. mutans.

Effects of phlorizin on diabetic retinopathy according to isobaric tags for relative and absolute quantification-based proteomics in db/db mice.

PURPOSE: Diabetic retinopathy (DR) is a leading cause of vision loss in working-age people. To retard the development and progression of retina lesions, effective therapeutic strategies directed toward key molecular targets are desired. Phlorizin is effective in treating diabetic complications, but little is known about functional protein changes that may mediate its actions. The aim of this study was to identify retinal proteomic alterations in db/db mice treated with phlorizin. METHODS: We used C57BLKS/J db/db mice as a type 2 diabetic animal model, while C57BLKS/J db/m mice were selected as the control. Phlorizin (20 mg/kg bodyweight /d) was administrated to db/db mice for ten weeks. Serum fasting blood glucose and advanced glycation end products were determined. Meanwhile, retina cell apoptosis was determined with terminal transferase dUTP nick end labeling. Isobaric tags for relative and absolute quantification and subsequent liquid chromatography-tandem mass spectrometry (LC-MS/MS) were used to identify and profile retinal proteins among control, untreated diabetic, and phlorizin-treated db/db mice. The expression of glial fibrillary acidic protein was measured in retinas using western blotting analysis. RESULTS: Phlorizin treatment significantly reduced fasting blood glucose and levels of advanced glycation end products (p<0.05) and remarkably inhibited retina cell apoptosis and the expression of glial fibrillary acidic protein in the retinas of db/db mice. In addition, we identified 1,636 proteins from retina tissue in total, of which 348 proteins were differentially expressed in db/db mice compared with the controls. Only 60 proteins in the retinas of the db/db mice were found to be differentially changed following phlorizin treatment, including 33 proteins that were downregulated and 27 proteins that were upregulated. Most of these differentially changed proteins were involved in oxidative stress, apoptosis, energy metabolism, and signaling transduction. CONCLUSIONS: Our study revealed the expression of proteins differentially changed after phlorizin therapy. These proteins are most likely to participate in the development and recovery of DR. Our findings help expand understanding of the mechanism underlying the onset and progression of DR, and provide novel targets for evaluating the effects of phlorizin therapy.

The effect of human papillomavirus status on prognosis and local treatment strategies of T1-2N0 oropharyngeal squamous cell cancer.

Purpose: To explore the effect of human papillomavirus (HPV) status on prognosis and further investigate whether human papillomavirus (HPV) status has an impact on the local treatment strategies for T1-2N0 oropharyngeal squamous cell cancer (OPSCC) patients. Methods: Patients diagnosed with T1-2N0 OPSCC between 2010 and 2015 were included from the Surveillance, Epidemiology, and End Results database. Data were analyzed using propensity score matching (PSM), Chi-square test, Kaplan-Meier survival analysis, and Cox multivariable analyses. Results: A total of 1,004 patients were identified, of whom 595 (59.3%) had HPV-related tumors. Of all the patients, 386 (38.4%) and 618 (61.6%) received definitive radiotherapy and radical surgery, respectively. HPV status had no significant effect on local treatment strategies for early-stage OPSCC (P = 0.817). The 3-year cancer-specific survival (CSS) and overall survival (OS) were 89.6 and 80.1%, respectively. Compared to those with HPV-negative diseases, patients with HPV-positive diseases had better CSS and OS. A total of 222 pairs of patients were completely matched after PSM. The results of multivariate Cox regression analysis showed that patients with HPV-positive disease had significantly better CSS (P = 0.001) and OS (P < 0.001) compared to those with HPV-negative tumors. However, local treatment strategy was not associated with survival outcomes after PSM (CSS, P = 0.771; OS, P = 0.440). The subgroup analysis showed comparable CSS and OS between those treated with radical surgery and definitive radiotherapy regardless of HPV status. Conclusions: HPV status is an independent prognostic factor for the survival of stage T1-2N0 OPSCC patients. Local treatment strategies had no significant effect on the survival of early-stage OPSCC regardless of HPV status. Patients with early-stage OPSCC should be informed regarding the pros and cons of definitive radiotherapy or radical surgery.

[Purification Efficiency and Microbial Characteristics of Four Biofilters Operated Under Different Conditions].

To explore the effects of aeration, microbial acclimation period, and pool shape or flow pattern change on the purification efficiency of biofilters at the microbiological level, four biofilters with different working conditions, that is, MAVF, NAVF, NVF, and BHF, were studied. The first three are vertical-flow biofilters and the last one is a baffled-flow biofilter. The four filters filled with the same ceramsite were made of organic glass. The MAVF filter was connected with the BHF filter in series and was operated for one year prior to the trial. The NAVF and NVF filters are newly activated filters. The four filters that were used to treat domestic sewage were synchronously operated in batch mode in this study. The MAVF and NAVF filters were intermittently aerated in contrast to the other two. During the period of microbial acclimation of the newly activated filters, the purification efficiency of the four filters was continuously monitored and the microbial community structure characteristics were analyzed at the end of microbial acclimation. The results show that the purification efficiency of the three vertical-flow filters is significantly higher than that of the horizontal-flow one and aeration significantly enhances the purification efficiency. However, aeration has a weaker effect on the efficiency than the microbial maturity of the filter. An apparent accumulation of nitrates or nitrites in the four filters was not observed, indicating that the denitrification was rather thorough. The 16S rDNA high-throughput sequencing analysis shows that the diversity index of the four filters is BHF > MAVF > NAVF > NVF, indicating that the more mature the filter is, the higher is the diversity index. Most of the packing microorganisms are facultative heterotrophic bacteria and the most abundant are heterotrophic denitrifying bacteria. Heterotrophic nitrification occurs in the NVF and BHF filters and aeration promotes the enrichment of aerobic ammonium-oxidizing bacteria. Aerobic phosphorus-accumulating organisms were not detected in the four filters. Therefore, phosphorus was mainly removed via denitrifying phosphorus accumulation. Under the test conditions, the removal rate of total nitrogen was not high, mainly because nitrifying bacteria were not enriched in the filter or their abundance was insufficient. The latter resulted in the limited ammonium-oxidizing ability of the filter, thus affecting the removal of total nitrogen. The above-mentioned results show that the adjustment of different working conditions will affect the redox status and associated enrichment of functional bacteria inside the biofilter, which will ultimately affect the purification efficiency.

[Purification Efficiency and Influencing Factors of Combined Bio-filters for Aquaculture Wastewater].

As an effective technology for wastewater treatment, bio-filter has been widely used. Nevertheless, there is still a lack of systematic report on purification efficiency and influencing factors of combined bio-filters. To this end, a novel combined system that consisted of aerated vertical-flow filter (AVF) followed by baffled horizontal-flow filter (BHF) was designed. After setting a series of hydraulic loading rates (131, 94 and 60 mm·d-1) and diversion ratios (8:2、6:4、4:6), we comprehensively assessed the impact of running condition adjustment on treatment performance by multiple statistical analyses. The results showed that, the average removal rates of organic matter, ammonia nitrogen and dissolved nitrogen in AVF were all above 80%, while the average removal rates of ammonia nitrogen, total nitrogen and dissolved nitrogen in BHF were all below 40%. Different running conditions had a significant (P<0.05) impact on treatment performance. Meanwhile, there were significant differences in purification efficiency between the two different kinds of filters. Oxidative degradation was one of the main ways to remove organic matter in the two kinds of filters. There were obvious nitrification and denitrification processes within the two kinds of filters. Nitrification followed by denitrification was the main way to remove total nitrogen since ammonium occupied the most portion of total nitrogen in the synthetic wastewater. Meanwhile, the intensity of nitrification and denitrification in AVF was obviously higher than that in BHF. Phosphorus removal was mainly controlled by hydraulic loading rate, temperature, dissolved oxygen, organic matter, etc. This might indicate that microbial absorption was one of the main ways to remove phosphorus for the two filters. Compared to the sole AVF, the removal of total organic matter and total phosphorus in the combined system was increased by 4.4% and 23.2%, respectively, but the removal of total nitrogen was reduced by 12.1%. Reducing the diversion ratio was helpful to improve the denitrification intensity in BHF. However, due to the introduction of excessive ammonia from the raw wastewater, as well as the limited nitrification capacity in BHF, the removal rate of total nitrogen for the combined system was decreased. Therefore, according to the composition of treated raw wastewater, the control of appropriate diversion ratio, residence time and redox conditions inside the filter bed was the key to enhance the overall performance of the combined system.

Differences in esophageal cancer characteristics and survival between Chinese and Caucasian patients in the SEER database.

BACKGROUND: To compare the clinicopathologic characteristics and survival of Chinese and Caucasian esophageal cancer (EC) patients residing in the US, using a population-based national registry (Surveillance Epidemiology and End Results [SEER]) database. METHODS: Patients with EC were identified from the SEER program from 1988 to 2012. Kaplan-Meier survival methods and Cox proportional hazards regression were performed. RESULTS: A total of 479 Chinese and 35,748 Caucasian EC patients were identified. Compared with Caucasian patients, the Chinese patients had a later year of diagnosis, remained married after EC was diagnosed, had esophageal squamous cell carcinomas (ESCCs) more frequently, had tumors located in the upper-third and middle-third of the esophagus more frequently, and fewer patients presented with poorly/undifferentiated EC and underwent cancer-directed surgery. In Chinese patients, the incidence of esophageal adenocarcinomas (EACs) increased from 1988 to 2012 (P=0.054), and the majority of EAC patients had tumors located in the lower thoracic esophagus. The overall survival (OS) was not significantly different between Chinese and Caucasian patients (P=0.767). However, Chinese patients with ESCC had a significantly better OS when compared to their Caucasian counterparts, whereas there was no significant difference in the OS between Chinese and Caucasian patients with EAC. CONCLUSION: The presenting demographic features, tumor characteristics, and outcomes of EC patients differed between Chinese and Caucasian patients residing in the US. Chinese patients diagnosed with EAC tended to share similar clinical features with their Caucasian counterparts, and the Chinese patients with ESCC had better OS than their Caucasian counterparts.

Molecular characterization of multidrug-resistant Klebsiella pneumoniae isolates.

Klebsiella pneumoniae is an important cause of healthcare-associated infections worldwide. Selective pressure, the extensive use of antibiotics, and the conjugational transmission of antibiotic resistance genes across bacterial species and genera facilitate the emergence of multidrug-resistant (MDR) K. pneumoniae. Here, we examined the occurrence, phenotypes and genetic features of MDR K. pneumoniae isolated from patients in intensive care units (ICUs) at the First Affiliated Hospital of Xiamen University in Xiamen, China, from January to December 2011. Thirty-eight MDR K. pneumoniae strains were collected. These MDR K. pneumoniae isolates possessed at least seven antibiotic resistance determinants, which contribute to the high-level resistance of these bacteria to aminoglycosides, macrolides, quinolones and ß-lactams. Among these isolates, 24 strains were extended-spectrum ß-lactamase (ESBL) producers, 2 strains were AmpC producers, and 12 strains were both ESBL and AmpC producers. The 38 MDR isolates also contained class I (28/38) and class II integrons (10/38). All 28 class I-positive isolates contained aacC1, aacC4, orfX, orfX' and aadA1 genes. ß-lactam resistance was conferred through bla SHV (22/38), bla TEM (10/38), and bla CTX-M (7/38). The highly conserved bla KPC-2 (37/38) and bla OXA-23(1/38) alleles were responsible for carbapenem resistance, and a gyrAsite mutation (27/38) and the plasmid-mediated qnrB gene (13/38) were responsible for quinolone resistance. Repetitive-sequence-based PCR (REP-PCR) fingerprinting of these MDR strains revealed the presence of five groups and sixteen patterns. The MDR strains from unrelated groups showed different drug resistance patterns; however, some homologous strains also showed different drug resistance profiles. Therefore, REP-PCR-based analyses can provide information to evaluate the epidemic status of nosocomial infection caused by MDR K. pneumoniae; however, this test lacks the power to discriminate some isolates. Thus, we propose that both genotyping and REP-PCR typing should be used to distinguish genetic groups beyond the species level.

The first tritopic bridging ligand 1,3,5-tris(4-carboxyphenyl)-benzene (H3BTB) functionalized porous polyoxometalate-based metal-organic framework (POMOF): from design, synthesis to electrocatalytic properties.

Replacing the metal ions (or metal clusters) in routine MOFs with size-matched polyoxoanions to construct POM-based MOF materials (POMOF) combining well-defined crystalline structures, high surface area, regular and tunable cavities is the great challenge in the current POM chemistry area. In this work, we report a 2-fold interpenetrated porous POMOF, [TBA]6[H3PMo12O40]2[Zn8(BTB)2]·(∼35H2O), which exhibits effective catalytic activity towards bromate reduction, using the methodology of extension for the reduced transition-metal-grafted ε-Keggin polyoxoanions with an expanded tripodal bridging ligand of H3BTB. The simultaneous TGA/DSC-MS technique was applied in this work to identify the evolved gases and was proved to be an effective method for analysing the decomposition process.

Molecular characterization of multidrug-resistant Klebsiella pneumoniae isolates

Klebsiella pneumoniae is an important cause of healthcare-associated infections worldwide. Selective pressure, the extensive use of antibiotics, and the conjugational transmission of antibiotic resistance genes across bacterial species and genera facilitate the emergence of multidrug-resistant (MDR) K. pneumoniae. Here, we examined the occurrence, phenotypes and genetic features of MDR K. pneumoniae isolated from patients in intensive care units (ICUs) at the First Affiliated Hospital of Xiamen University in Xiamen, China, from January to December 2011. Thirty-eight MDR K. pneumoniae strains were collected. These MDR K. pneumoniae isolates possessed at least seven antibiotic resistance determinants, which contribute to the high-level resistance of these bacteria to aminoglycosides, macrolides, quinolones and β-lactams. Among these isolates, 24 strains were extended-spectrum β-lactamase (ESBL) producers, 2 strains were AmpC producers, and 12 strains were both ESBL and AmpC producers. The 38 MDR isolates also contained class I (28/38) and class II integrons (10/38). All 28 class I-positive isolates contained aacC1, aacC4, orfX, orfX’ and aadA1 genes. β-lactam resistance was conferred through bla_SHV (22/38), bla_TEM (10/38), and bla_CTX-M (7/38). The highly conserved bla_KPC-2 (37/38) and bla_OXA-23(1/38) alleles were responsible for carbapenem resistance, and a gyrAsite mutation (27/38) and the plasmid-mediated qnrB gene (13/38) were responsible for quinolone resistance. Repetitive-sequence-based PCR (REP-PCR) fingerprinting of these MDR strains revealed the presence of five groups and sixteen patterns. ...

Molecular characterization of multidrug-resistant Klebsiella pneumoniae isolates

Klebsiella pneumoniae is an important cause of healthcare-associated infections worldwide. Selective pressure, the extensive use of antibiotics, and the conjugational transmission of antibiotic resistance genes across bacterial species and genera facilitate the emergence of multidrug-resistant (MDR) K. pneumoniae. Here, we examined the occurrence, phenotypes and genetic features of MDR K. pneumoniae isolated from patients in intensive care units (ICUs) at the First Affiliated Hospital of Xiamen University in Xiamen, China, from January to December 2011. Thirty-eight MDR K. pneumoniae strains were collected. These MDR K. pneumoniae isolates possessed at least seven antibiotic resistance determinants, which contribute to the high-level resistance of these bacteria to aminoglycosides, macrolides, quinolones and β-lactams. Among these isolates, 24 strains were extended-spectrum β-lactamase (ESBL) producers, 2 strains were AmpC producers, and 12 strains were both ESBL and AmpC producers. The 38 MDR isolates also contained class I (28/38) and class II integrons (10/38). All 28 class I-positive isolates contained aacC1, aacC4, orfX, orfX’ and aadA1 genes. β-lactam resistance was conferred through blaSHV (22/38), blaTEM (10/38), and blaCTX-M (7/38). The highly conserved blaKPC-2 (37/38) and blaOXA-23(1/38) alleles were responsible for carbapenem resistance, and a gyrAsite mutation (27/38) and the plasmid-mediated qnrB gene (13/38) were responsible for quinolone resistance. Repetitive-sequence-based PCR (REP-PCR) fingerprinting of these MDR strains revealed the presence of five groups and sixteen patterns. ...