Search

This study developed a new single-tube multiplex real-time PCR method for detecting toxigenic C. difficile directly from fecal samples using tcdA, tcdB, cdtB, and internal gene tpi as targets, which could be performed on kinds of polymerase chain reaction device including point-of-care testing (POCT), with improved detection efficiency. The specificity, sensitivity, and repeatability of each gene was evaluated using 69 C. difficile isolates and 74 fecal samples. Results were compared with established PCR, qPCR, and ELISA methods. Interspecies specificity was 100% based on six common intestinal pathogens (Escherichia coli, Enterococcus Faecium, Enterococcus faecalis, Clostridium perfringens, Bacteroides fragilis, Clostridium botulinum). The lower detection limit (LDL) for tcdA, tcdB, and cdtB with pure C. difficile DNA was 101,100, and 100 copies/μL, respectively, the coefficients of variation among different experimental batches and within each experimental batch were both less than 3%, which shows that this method has strong repeatability. And the LDL of fecal DNA was 5 × 100, 5 × 103, and 5 × 102 colony-forming units (CFU)/g, respectively. In addition, the efficiency for detection of tcdA was compared with established PCR and real-time PCR methods, demonstrating high consistency (98.4%) and similar sensitivity. ELISA was used to confirm inconsistent results, which were identical with our method. The sensitivity and specificity for detecting toxigenic C. difficile in fecal samples were 96.49% and 94.12% compared with the toxigenic culture (TC). This method effectively identified the toxigenic and non-toxigenic strains with high specificity, sensitivity, and repeatability, and could reduce the false positive rate of tcdA, and accurately identify the typical Asian strain RT017, making it potentially contribute to the surveillance of CDI in China.

Clostridioides difficile is the predominant antibiotic-associated enteropathogen associated with diarrhoea or pseudomembranous colitis in patients worldwide. Previously, we identified C. difficile RT078 isolates (CD21062) from elderly patients in China, including two new ribotype strains (CD10010 and CD12038) belonging to the ST11 group, and their genomic features were also investigated. This study compared sporulation, spore germination, toxin expression, flagellar characteristics, and adhesion among these strains in vitro and analysed their pathogenic ability in vivo using animal models. The results showed sporulation and spore germination did not significantly differ among the three C. difficile strains. CD10010 and CD12038 showed higher transcriptional levels of toxins until 48 h; thereafter, the transcriptional levels of toxins remained constant among RT078, CD10010, and CD12038. RT078 showed a loss of flagellum and its related genes, whereas CD12038 showed the highest motility in vitro. Both CD10010 and CD12038 initially showed flg phase OFF, and the flagellar switch reversed to phase ON after 48 h in swim agar. Flagellar proteins and toxins were both upregulated when flg phase OFF changed to flg phase ON status, enhancing their pathogenic ability. CD12038 showed the highest adhesion to Hep-2 cells. Histopathology and inflammation scores demonstrated that CD12038 caused the most severe tissue damage and infection in vivo. The new ribotype strains, particularly CD12038, exhibit higher pathogenic ability than the typical RT078 strain, both in vitro and in vivo. Therefore, more attention should be paid to this new C. difficile strain in epidemiological research; further studies are warranted.

Background Clostridioides difficile is a major cause of antibiotic associated diarrhea. Several animal models are used to study C. difficile infection (CDI). The tree shrew has recently been developed as a model of primate processes. C. difficile infection has not been examined in tree shrews. We infected tree shrews with hyper-virulent C. difficile strains and examined the alterations in gut microbiota using 16S rRNA gene sequencing. Results C. difficile colonized the gastrointestinal tract of tree shrew and caused diarrhea and weight loss. Histopathologic examination indicated structures and mucosal cell destruction in ileal and colonic tissues. The gut microbial community was highly diversity before infection and was dominated by Firmicutes, Fusobacteria, Bacteroidetes, and Proteobacteria. Antibiotic administration decreased the diversity of the gut microbiota and led to an outgrowth of Lactobacillus. The relative abundance of Proteobacteria, Gammaproteobacteria, Enterobacteriales, Lachnospiraceae, Enterobacteriaceae, Escherichia, Blautia, and Tyzzerella increased following C. difficile infection. These taxa could be biomarkers for C. difficile colonization. Conclusions In general, the disease symptoms, histopathology, and gut microbiota changes following C. difficile infection in tree shrews were similar to those observed in humans.

Background It has been performed worldwidely to explore the potential of animals that might be a reservoir for community associated human infections of Clostridioides difficile. Several genetically undistinguished PCR ribotypes of C. difficile from animals and human have been reported, illustrating potential transmission of C. difficile between them. Pig and calf were considered as the main origins of C. difficile with predominant RT078 and RT033, respectively. As more investigations involved, great diversity of molecular types from pig and calf were reported in Europe, North American and Australia. However, there were quite limited research on C. difficile isolates from meat animals in China, leading to non-comprehensive understanding of molecular epidemiology of C. difficile in China. Results A total of 55 C. difficile were isolated from 953 animal stool samples, within which 51 strains were from newborn dairy calf less than 7 days in Shandong Province. These isolates were divided into 3 STs and 6 RTs, of which ST11/RT126 was predominant type, and responsible for majority antibiotic resistance isolates. All the isolates were resistant to at least one tested antibiotics, however, only two multidrug resistant (MDR) isolates were identified. Furthermore, erythromycin (ERY) and clindamycin (CLI) were the two main resistant antibiotics. None of the isolates were resistant to vancomycin (VAN), metronidazole (MTZ), tetracycline (TET), and rifampin (RIF). Conclusions In this study, we analyzed the prevalence, molecular characters and antibiotic resistance of C. difficile from calf, sheep, chicken, and pig in China. Some unique features were found here: first, RT126 not RT078 were the dominant type from baby calf, and none isolates were got from pig; second, on the whole, isolates from animals display relative lower resistant rate to these 11 tested antibiotics, compared with isolates from human in China in our previous report. Our study helps to deep understanding the situation of C. difficile from economic animals in China, and to further study the potential transmission of C. difficile between meat animals and human.

Clostridioides difficile is the predominant pathogen responsible for antimicrobial associated diarrhea (AAD) and health care facility-associated infectious diarrhea. The role of C. difficile in China and its impact on public health have gained attention in recent years. Most clinical C. difficile isolates in China belong to multilocus sequence type clade 1 with sequence types (STs) 3, 35 and 54 predominating. Of note, the proportion of C. difficile isolates from clade 4, especially ST37 (PCR ribotype 17), is much higher in China than in other areas. In China, the antimicrobial-resistance profile of C. difficile is similar to that of other countries, demonstrating a higher resistance rate to erythromycin, clindamycin, and fluoroquinolones (ciprofloxacin, levofloxacin, and moxifloxacin). In general, susceptibility to vancomycin and metronidazole of clinical C. difficile in China is high, however, some resistance to metronidazole have recently been reported. Preclinical research on C. difficile in animals in China is limited, and different studies have reported varied isolation rates and antimicrobial resistance profiles. The diverse molecular types of C. difficile in China merit further epidemiological, genomic and evolutionary investigation. While the use of probiotics in preventing C. difficile infection (CDI) have received both support and opposition, the discovery of new probiotics and new formulations are showing promising results in combating the threat posed by CDI.

The effects of grain size on the tellurium corrosion behaviors have been investigated systematically in GH3535 alloy. After the exposure to Te vapor, the triple-layer scales, which consist of Ni3Te2, Cr3Te4, MnTe, M6C carbides and Fe-riched γ phase, occur in both the fine-grained and coarse-grained specimens. The thicker outer layer, the more discrete inner layer, the shallower Te permeation and Cr3Te4 existence along grain boundaries can be observed in the fine-grained specimens. By comparing the Gibbs free energies and calculating the effective diffusion coefficients, the tellurization mechanism and the role of grain size were discussed.

To identify the prevalence and characteristics of community-acquired Clostridium difficile infection (CA-CDI) in southwest China, we conducted a cross-sectional study. 978 diarrhea patients were enrolled and stool specimens’ DNA was screened for virulence genes. Bacterial culture was performed and isolates were characterized by PCR ribotyping and multilocus sequence typing. Toxin genes tcdA and/or tcdB were found in 138/978 (14.11%) cases for fecal samples. A total of 55 C. difficile strains were isolated (5.62%). The positive rate of toxin genes and isolation results had no statistical significance between children and adults groups. However, some clinical features, such as fecal property, diarrhea times before hospital treatment shown difference between two groups. The watery stool was more likely found in children, while the blood stool for adults; most of children cases diarrhea ≤3 times before hospital treatment, and adults diarrhea >3 times. Independent risk factor associated with CA-CDI was patients with fever. ST35/RT046 (18.18%), ST54/RT012 (14.55%), ST3/RT001 (14.55%) and ST3/RT009 (12.73%) were the most distributed genotype profiles. ST35/RT046, ST3/RT001 and ST3/RT009 were the commonly found in children patients but ST54/RT012 for adults. The prevalence of CA-CDI in Yunnan province was relatively high, and isolates displayed heterogeneity between children and adults groups.

The effect of grain boundary engineering (GBE) on the Te diffusion along the surface grain boundaries was investigated in GH3535 alloy. It can be found that GBE treatment increases obviously the fraction of low-Σ coincidence site lattice (CSL) boundaries, especially the Σ3 ones, and introduces the large-size grain clusters. When the as-received (AR) and GBE-treated (GBET) specimens were exposed to Te vapor, only Σ3 boundaries were found to be resistant to Te diffusion. From the cross section and the surface, the fewer Te-attacked grain boundaries and the thinner corrosion layer can be observed in the GBET sample. The improvement of resistance to Te diffusion in the GBET sample can be attributed to the large size grain-clusters associated with high proportion of the Σ3n boundaries.

The evolution of grain boundary MC carbides during the thermal exposure has been investigated in the Ti-modified Hastelloy N alloy. MC carbides precipitate at the grain boundaries after exposed at 650 °C and 750 °C for 500 hours (h). The morphology of MC carbides at the grain boundaries was characterized as separated particles with a cube-on-cube orientation relationship with the matrix. The MC/Matrix interface exhibits a semi-coherent character, on which misfit dislocations are repeated in every sixth layer of (111) MC . With the further thermal exposure, the size of MC carbides remain stable at 650 °C. By contrast, M 2 C carbides undergo the initial coarsening and subsequent re-dissolution at 750 °C. At the same time, the deviation angles from the cube-cube orientation relationship (OR) between MC carbides and the matrix become larger at both 650 °C and 750 °C, which indicate the semi-coherent interfaces are transforming to the incoherent ones.

The effect of silicon additions on the primary carbides and second grain boundary carbides has been investigated in as-cast and wrought Ni-Mo-Cr based alloys, respectively. With the increase of Si content in the as-cast alloys, the lamellar M2C eutectic carbides at grain boundaries were replaced by skeleton-shape M6C eutectic carbides in interdendritic regions. The wrought alloys with different Si contents were thermal exposed at 750 °C for 1, 500 and 2000 h, respectively. It can be observed that the initial M2C carbides formed at grain boundaries were replaced by M6C carbides in the low-Si alloys (0.051 and 0.188 wt.%) with the increase of exposure time. Only M6C carbides precipitated at grain boundaries in the alloy with 0.562 wt.% Si, which coarsened during the thermal exposure. Similar trends also existed in the high-Si alloy except an abnormal formation of M2C carbides after 2000 h' exposure. The effect of Si additions on the types of carbides was attributed to competitive nucleation between M2C carbides and M6C carbides based on classical nucleation theory. Keywords: Si content, Grain boundary carbides, Electron backscatter diffraction, Ni-Mo-Cr

Mobile genetic elements play a key role in the continuing evolution of Clostridium difficile, resulting in the emergence of new phenotypes for individual isolates. On the basis of whole-genome sequencing analysis, we comprehensively explored transposons, CRISPR, prophage, and genetic sites for drug resistance within clade 4 C. difficile isolates with different sequence types. Great diversity in MGEs and a high rate of multidrug resistance were found within this clade, including new transposons, Tn4453a/b with aac(6′) aph(2′′) instead of catD, and a relatively high rate of prophage-carried CRISPR arrays. These findings provide important new insights into the mechanism of genome remodeling within clade 4 and offer a new method for typing and tracing the origins of closely related isolates., Horizontal gene transfer of mobile genetic elements (MGEs) accounts for the mosaic genome of Clostridium difficile, leading to acquisition of new phenotypes, including drug resistance and reconstruction of the genomes. MGEs were analyzed according to the whole-genome sequences of 37 C. difficile isolates with a variety of sequence types (STs) within clade 4 from China. Great diversity was found in each transposon even within isolates with the same ST. Two novel transposons were identified in isolates ZR9 and ZR18, of which approximately one third to half of the genes showed heterogenous origins compared with the usual intestinal bacterial genes. Most importantly, catD, known to be harbored by Tn4453a/b, was replaced by aac(6′) aph(2′′) in isolates 2, 7, and 28. This phenomenon illustrated the frequent occurrence of gene exchanges between C. difficile and other enterobacteria with individual heterogeneity. Numerous prophages and CRISPR arrays were identified in C. difficile isolates of clade 4. Approximately 20% of spacers were located in prophage-carried CRISPR arrays, providing a new method for typing and tracing the origins of closely related isolates, as well as in-depth studies of the mechanism underlying genome remodeling. The rates of drug resistance were obviously higher than those reported previously around the world, although all isolates retained high sensitivity to vancomycin and metronidazole. The increasing number of C. difficile isolates resistant to all antibiotics tested here suggests the ease with which resistance is acquired in vivo. This study gives insights into the genetic mechanism of microevolution within clade 4. IMPORTANCE Mobile genetic elements play a key role in the continuing evolution of Clostridium difficile, resulting in the emergence of new phenotypes for individual isolates. On the basis of whole-genome sequencing analysis, we comprehensively explored transposons, CRISPR, prophage, and genetic sites for drug resistance within clade 4 C. difficile isolates with different sequence types. Great diversity in MGEs and a high rate of multidrug resistance were found within this clade, including new transposons, Tn4453a/b with aac(6′) aph(2′′) instead of catD, and a relatively high rate of prophage-carried CRISPR arrays. These findings provide important new insights into the mechanism of genome remodeling within clade 4 and offer a new method for typing and tracing the origins of closely related isolates.

Background: Adhesion, biofilm formation, yeast-hyphal transition, secretion of enzymes, and hemolytic activity are all considered important factors in Candida tropicalis infection. However, DNA sequence data for this pathogen are limited. In this study, the polymorphism and heterogeneity of genes agglutinin-like sequences (ALS)2, Lipase (LIP)1, LIP4, and secretory aspartyl proteinase tropicalis (SAPT)1-4 as well as the relationship between phenotype and genotype were analyzed. Methods: This study started in August 2013, and ended in July 2017. The complete length of ALS2, LIP1, LIP4, and SAPT1-4 of 68 clinical C. tropicalis isolates was sequenced. Single nucleotide polymorphisms (SNPs) as well as insertions and deletions (indels) were identified within these genes. In addition, phenotypic characteristics of the virulent factors, including adhesion and the secretion of aspartyl proteinases and phospholipases, were determined. Results: There were 73, 24, 17, 16, 13, and 180 SNPs in the genes LIP1, LIP4, SAPT1, SAPT2, SAPT3, and SAPT4, respectively. Furthermore, 209 SNPs were identified in total for the gene ALS2. Interestingly, large fragment deletions and insertions were also found in ALS2. Isolate FXCT 01 obtained from blood had deletions on all 4 sites and showed the lowest adhesion ability on the polymethylpentene surface. In addition, isolates with deletions in the regions 1697 to 1925 and 2073 to 2272 bp displayed relatively low abilities for adhesion and biofilm formation, and this phenotype correlated with the deletions found in ALS2. LIP1, SAPT4, and ALS2 displayed great heterogeneity among the isolates. Large deletions found in gene ALS2 appeared to be associated with the low ability of adhesion and biofilm formation of C. tropicalis. Conclusion: This study might be useful for deeper explorations of gene function and studying the virulent mechanisms of C. tropicalis. Key words: Candida tropicalis; Virulence-related genes; Phylogenetic analysis; Gene ALS; Gene LIP; Gene SAP

BackgroundClade 5Clostridioides difficilediverges significantly from the other clades and is therefore, attracting increasing attention due its great heterogeneity. In this study, we used third-generation sequencing techniques to sequence the complete whole genomes of three ST11C. difficileisolates, RT078 and another two new ribotypes (RTs), obtained from three independent hospitalized elderly patients undergoing antibiotics treatment. Mobile genetic elements (MGEs), antibiotic-resistance, drug resistance genes, and virulent-related genes were analyzed and compared within these three isolates.ResultsIsolates 10,010 and 12,038 carried a distinct deletion intcdAcompared with isolate 21,062. Furthermore, all three isolates had identical deletions and point-mutations intcdC, which was once thought to be a unique characteristic of RT078. Isolate 21,062 (RT078) had a unique plasmid, different numbers of transposons and genetic organization, and harboring special CRISPR spacers. All three isolates retained high-level sensitivity to 11 drugs and isolate 21,062 (RT078) carried distinct drug-resistance genes and loss of numerous flagellum-related genes.ConclusionsWe concluded that capillary electrophoresis based PCR-ribotyping is important for confirming RT078. Furthermore, RT078 isolates displayed specific MGEs, indicating an independent evolutionary process. In the further study, we could testify these findings with more RT078 isolates of divergent origins.

Nickel and some nickel-base alloys are extremely sensitive to intergranular embrittlement and tellurium (Te) enhanced cracking, which should be concerned during their serving in molten salt reactors. Here, a systematic study about the effects of its temperature on the reaction products at its surface, the intergranular diffusion of Te in its body and its embrittlement for a Ni-16Mo-7Cr alloy contacting Te is reported. For exposed to Te vapor at high temperature (823-1073 K), the reaction products formed on the surface of the alloy were Ni3Te2, CrTe, and MoTe2, and the most serious embrittlement was observed at 1073 K. The kinetic measurement in terms of Te penetration depth in the alloy samples gives an activation energy of 204 kJ/mol. Electron probe microanalysis confirmed the local enrichment of Te at grain boundaries. And clearly, the embrittlement was results from the intergranular diffusion and segregation of element Te. (C) 2015 Elsevier B.V. All rights reserved.

It is known that antibiotic usage is associated with the development of Clostridioides difficile infection (CDI), especially clindamycin, third-generation cephalosporins, and fuoroquinolones. Antibiotic resistance rates to many antibiotics varies a lot by study. We performed a study focused on antibiotic resistance in clinical isolates of C. difficile from more widespread geographic regions across China. Of 319 C. difficile isolates tested against 11 antibiotics, 313 (98.1%) were resistant to at least one antibiotic. The highest rate of resistance was to ciprofloxacin, clindamycin, and erythromycin across all age groups, similar to previous studies. However, all isolates were susceptible to metronidazole and vancomycin. Overall the resistance rate to tested antibiotics was lower than other reports in China except for chloramphenicol and meropenem. Genotype ST37/RT017 in clade 4 was resistant to more antibiotics than other types. Unexpectedly, RT078 isolates in this study were susceptible to almost all tested antibiotics. In addition, the proportion of multi-drug resistant (MDR) isolates observed (17%) in this study was much lower than several European studies (up to 55%) and a previous study in China (78%). Although isolates from patients aged between 65 and 85 were more resistant to antibiotics in comparison to other age groups, MDR isolates were still detected in children below 2-years of age. The highest percentage of MDR isolates was determined in South China, an area that is most developed economically. The clade 4, RT017 (ST37) has been associated with outbreaks in Europe and North America and is responsible for most C. difficile infections (CDIs) in Asia. In addition, RT017 is often clindamycin and fluoroquinolone resistant. This study provided a relatively comprehensive description of antibiotic resistance of C. difficile in China, and further elucidates the epidemiology and antibiotic resistance of clinical isolates of C. difficile in China at a national level.

Clostridium difficile infection (CDI) has become a worldwide public health problem causing high mortality and a large disease burden. Molecular typing and analysis is key important for surveillance and infection control of CDI. However, molecular characterization of C. difficile across China is extremely rare. To investigate the multicenter data of C. difficile isolates across China, the toxin profile, molecular types, and epidemiological characteristics of C. difficile were analyzed. A total of 199 C. difficile isolates collected from 2010-2015 were analyzed using multilocus sequence typing (MLST), PCR ribotyping, and toxin genes amplification. There were 35 STs and 27 ribotypes (RTs) identified in this study, in which ST35 (15.58%), ST3 (15.08%), ST37 (12.06%) and RT017 (14.07%), RT001 (12.06%), RT012 (11.56%), are the most prevalent types, respectively. One isolate with ST1 and 8 isolates with ST 11 were identified. We identified a new ST in this study, denoted ST332. The toxin profile tcdA+tcdB+tcdC+tcdR+tcdE+CDT- (65.83%) was the predominant profile. Furthermore, 11 isolates with positive binary toxin genes were discovered. According to the PCR ribotyping, ST1 was confirmed as RT 027, and 6 out of the 8 ST11 strains were confirmed as RT 078. The epidemiological characteristics of C. difficile in China shows geographical differences, and both the toxin profile and molecular types exhibit great diversity across the different areas.

A microfluidic chip with integrated microelectrodes for real-time dopamine (DA) detection was designed and fabricated. The chip consisted of a polydimethylsiloxane (PDMS) channel plate and a glass electrode plate. One central channel as the culture chamber of neural stem cells and two lateral channels for the transportation of the culture medium were integrated on the PDMS channel plate. Microelectrodes for real-time dopamine detection were integrated on the glass electrode plate. To solve the problem in demoulding the PDMS channel plate from the silicon mold, a novel demoulding method was developed. An Au-Au-Au three-electrode system was constructed, and it performed well in electrochemical detection. The performance of the microfluidic chip was primarily studied by detecting dopamine dissolved in the medium for the culture of neural stem cells. The detection limit of dopamine was 3.92 μM, the linear detection range was from 10 μM to 500 μM, and the detection reproducibility from different chips was less than 4%.

BACKGROUND In this work, novel multisensitive composites of poly(N-isopropylacrylamide-co-acrylic acid-co-cobalt tetra(N-carbonylacrylic) aminophthalocyanine))/TiO2 (poly(NIPAM-co-AAc-co-CoMPc)/TiO2) were prepared to address the problems of low efficiency for utilizing solar light and difficult separation and recovery of nanometer sized TiO2 particles in the photocatalytic degradation of dinitro butyl phenol (DNBP) in wastewater. RESULTS The results showed that nanometer sized TiO2 particles were successfully encapsulated in multisensitive polymer carriers of spherical shape and that the composite photocatalyst can be activated by both ultraviolet and visible light. The synthesized composites exhibited high sensitivity to external temperature and pH stimuli. The satisfactory removal of DNBP from aqueous solution can be achieved at pH 5.62 with catalyst concentration of 6 g L−1 under visible light irradiation for 5 h. The multisensitive composites prepared in this study have repeatability. CONCLUSION The synthesized multisensitive composites can be used to perform ‘on-off’ photocatalytic degradation of organic contaminants in water under visible light irradiation by controlling temperature or pH. © 2013 Society of Chemical Industry

In this paper, the protective electroless Ni-P/SiC gradient coatings on AZ91D magnesium alloy substrate were successfully prepared. The prepared Ni-P/SiC gradient coatings were characterized for its microstructure, morphology, microhardness and adhesion to the substrate. The deposition reaction kinetics was investigated and an empirical rate equation for electroless Ni-P/SiC plating on AZ91D magnesium alloy was developed. The anticorrosion properties of the Ni-P/SiC gradient coatings in 3.5 wt.% NaCl solution were evaluated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) studies. The potentiodynamic polarization measurements revealed that the SiC concentration in the bath and heat treatment can influence the corrosion protection performance of electroless deposited Ni-P/SiC gradient coatings. EIS studies indicated that higher charge transfer resistance and slightly lower capacitance values were obtained for Ni-P/SiC gradient coatings compared to Ni-P coatings. The corrosion resistance of the Ni-P/SiC gradient coatings increases initially and decreases afterwards with the sustained increasing of immersion time in the aggressive medium. The electroless Ni-P/SiC gradient coatings can afford better corrosion protection for magnesium alloy substrate compared with Ni-P coatings.

Co-diffusion characteristics of Er3+ and Tm3+ ions in LiNbO3 crystal have been studied, together with two other properties: doping effect on refractive index of substrate, and Li out-diffusion. Er3+/Tm3+-codoped LiNbO3 single-crystals were prepared by co-diffusion of stacked Er- and Tm-metal thin films, coated onto parts of the surfaces of X- and Z-cut congruent LiNbO3 crystal plates, at different temperatures and different durations in air. After diffusion, the surface refractive indices of the doped and undoped parts were measured by prism coupling technique, and the surface composition was evaluated from the measured indices. The results show that the dopings have negligible effect on the substrate index and the Li out-diffusion depends mainly on the diffusion temperature. The Er3+ and Tm3+ profiles were studied using secondary ion mass spectrometry, and a co-diffusion dynamical model is proposed and verified experimentally. From the measured profiles, the temperature-dependent Er3+/Tm3+ diffusivity and solubility were obtained together with other relevant parameters, such as diffusion constant, activation energy, solubility constant and heat of solution. The Er3+ and Tm3+ co-diffusion exhibits similar temperature dependent diffusivity, and the dependence is similar to that of single-diffusion. In the co-diffusion case, the total solubility consists of two parts: Er3+ and Tm3+ parts, there is no anisotropy, and the value is equal to that of single-diffusion case, in which both ions have the similar solubility. The Er3+ and Tm3+ parts of solubility change relatively with the initial metal film thicknesses and hence have different temperature dependences. Nevertheless, their sum, i.e., the co-diffusion solubility, remains a constant at a given temperature.

Diffusion properties of Tm3+ in congruent LiNbO3 crystal have been investigated, together with other two related issues, i.e., Tm3+-doping contribution to refractive index of LiNbO3 substrate and Li out-diffusion. Four X-cut and four Z-cut congruent LiNbO3 substrates locally coated with 15–31 nm-thick Tm-metal films were annealed in surrounding air under different temperatures of 1030°C–1130°C for different durations of 20–70 h. After anneal, refractive index at Tm3+-doped and Tm3+-free parts of crystal surface was measured at the wavelengths of 1311 and 1553 nm and surface Li2O contents were evaluated from measured refractive index. The results show that Tm3+ doping has a weak effect on substrate index and a small contribution to index increment in waveguide layer in comparison with Ti4+- or Zn2+ doping. The Li2O content at the Tm3+-doped surface equals that at the Tm3+-free surface. The Li out-diffusion depends mainly on the diffusion temperature. Below 1100°C, the Li out-diffusion is not measurable. At 1130°C, a 30-h diffusion procedure may cause 0.2–0.3 mol% slight loss of Li2O content. Secondary ion mass spectrometry was used to study the Tm3+ diffusion properties. The results show that the diffused Tm3+ ions in all samples follow a complementary error function profile. From measured Tm3+ profiles, characteristic diffusion parameters such as diffusivity, diffusion constant, activation energy, solubility, solubility constant, and heat of solution were obtained and discussed in comparison with the case of Er3+ diffusion. In comparison with Er3+ diffusion, the Tm3+ diffusion shows similar anisotropy and temperature dependence of solubility. In the aspect of diffusivity, under lower temperature the Tm3+ has a lower diffusivity than the Er3+, and their diffusivity difference reduces with the increased temperature and becomes null at 1130°C.

Based on the unique temperature responsive characters of polymeric material based on N-isopropylacrylamide (NIPAM), a capacity for organic molecular inclusion of maleic anhydride (MAH) modified β-cyclodextrin (β-CD), and the enhancements in photocatalytic activity of TiO2 doped with multi-walled carbon nanotubes (MWCNTs), the novel thermosensitive poly(NIPAM-co-MAH-β-CD)/(TiO2-MWCNTs) composite photocatalysts were prepared by UV light photoinitiating method. Fourier transform infrared spectra (FTIR), X-ray diffraction (XRD), thermal gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), BET surface area and UV–Vis diffuse reflectance spectra (UV–Vis/DRS) were used to characterize the structure, morphology and composition of the as-prepared composites. Results showed that TiO2-MWCNTs nanoparticles were embedded evenly within the thermally responsive copolymer of NIPAM and MAH-β-CD. The thermoresponsive property of the synthesized composites was investigated by using swelling ratio measurements. The photocatalytic performances of the thermosensitive composite catalysts were evaluated for the degradation of 2-sec-butyl-4,6-dinitrophenol (DNBP) solution under visible light irradiation. The effect of operational parameters, i.e. pH of the solution, catalyst concentration, irradiation time, initial DNBP concentration on the photocatalytic degradation efficiency was explored and the results obtained were fitted with modified Langmuir–Hinshelwood model to investigate the degradation kinetics and discussed in detail. The repeatability of photocatalytic activity was also tested. The thermosensitive composite photocatalysts exhibited easy separation and less deactivation after several runs. A plausible mechanism is proposed for the photocatalytic degradation pathway of DNBP. The results of this study showed the feasible and potential use of the thermosensitive composites in photodegradation of organic pollutants by controlling temperature simply.

Rare-earth-doping and various post-growth heat treatments effects on OH − absorption in singly Er- and Yb-doped, doubly Er/Mg- and Er/Yb-doped LiNbO 3 crystals have been investigated. The OH − absorption in the rare-earth-doped crystals shows definite anisotropy and is stronger in a Z-cut plate. Rare-earth-doping causes considerable OH − absorption reduction. MgO-codoping induces additional reduction. Slight/heavy rare-earth-doping causes slight/considerable spectral shape change. Thermal reduction treatment causes OH − absorption vanishing whether the crystal is originally congruent or near-stoichiometric. Further oxidation treatment renders the absorption reemerged. Li-rich vapor transport equilibration (VTE) treatment causes significant absorption decrease. For a slightly rare-earth-doped Li-rich VTE-treated crystal, its spectral feature is similar to that of the undoped near-stoichiometric crystal; for a heavily rare-earth-doped VTE-treated crystal, its spectral shape preserves the feature of the heavily rare-earth-doped as-grown crystal. For the Er/Mg-codoped crystal studied, the Li-rich VTE also induces an abrupt conversion of peaking position from 3483 cm −1 to 3535 cm −1 . The absorption in the Li-rich VTE-treated crystals also reveals aging effects in spectral shape, peaking position and absorption intensity. Li-poor VTE induces significant absorption increase. In addition, the effect of OH − presence on lifetime of Er 3+ emission at 1.5 μm was also studied. The results show that the effect is small for the as-grown congruent crystals and slight for Li-rich VTE-treated ones.

Diffusion characteristics of Zr4+ in LiNbO3 single-crystal were studied. Zr4+-doped LiNbO3 crystal plates were prepared by in-diffusion of 100 nm thick ZrO2 film coated onto Z-cut congruent substrates in wet O2 at different temperatures. Zr4+-diffused profile was analyzed by secondary ion mass spectrometry. The results show that the Zr4+ diffusion follows the traditional diffusion theory. From the measured profiles, important diffusion parameters are obtained, such as diffusivity and its temperature dependence, diffusion constant, activation energy, surface concentration, and solubility. The Zr4+ has a diffusivity similar to that of Ti4+, implying that the Zr4+ doping and the Ti4+ diffusion can be performed simultaneously to simplify the fabrication process of a photorefractive-damage-resistant Zr4+-doped Ti-diffused LiNbO3 waveguide.

The aim of the study was to evaluate the potential role of CD40/CD40 ligand (CD40L) and CD134/CD134 ligand (CD134L) in the development of coronary heart disease (CHD) via the performance of a case-control study.The research objects were 234 cases of CHD patients and 120 cases of well-matched

Myocardial infarction (MI) remains the major cause of death and disability in the world, and intramyocardial administration of biomaterials (e.g., hydrogels) along the perimeter of MI region is demonstrated as an effective way for the treatment of MI. The curcumin has anti-inflammation, antioxidation, and antiapoptosis properties, and nitric oxide (NO) molecules are favorable for angiogenesis. This study prepares a mixed component hydrogel capable of releasing both bioactive curcumin and NO for the treatment of MI. The study shows that the combinational treatment of curcumin and NO can remarkably reduce collagen deposition, improve cardiac function, ameliorate adverse myocardium remodeling, suppress apoptosis, and hypertrophy as well as attenuate the expression of matrix metalloproteinases (MMPs) and transforming growth factor-β1 (TGF-β1) and upregulate the expression of silent information regulator 1 than curcumin alone, because of the synergistic action of both molecules and the angiogenesis promotion ability of NO. The results indicate that codelivery of curcumin and NO in a controllable manner by hydrogels might be considered as a promising option for treatment of cardiovascular disease.

To observe the clinical effects of partial revascularization on elderly patients with coronary artery diseases(CAD) METHODS: Percutaneous coronary interventions (PCI) of the most likely culprit vessels were performed in 37 patients over 80 years old with multivessel coronary artery diseases (CAD).The success rate of PCI was 100% in these elderly patients without serious complications. The in-hospital mortality rate was 2.7%, and all the other patients recovered and were discharged.Partial revascularization for elderly CAD patients can achieve satisfactory clinical results, and close attention should be given to the heart and kidney function of these patients.

To assess the therapeutic effect and safety of electroacupuncture (EA) at Zhigou (TE 6) on constipation induced by stagnation or deficiency of qi.Multi-central randomized controlled trials were adopted and the patients conforming to the criteria for diagnosis, enrolling and excluding were divided into an observation group and a control group according to random number table. The observation group were treated with EA at Zhigou (TE 6) and the control group with EA at non-acupoint for 4 weeks. The cumulative score of clinical symptoms, colon transmission test and various safety indexes were assessed. The following-up was carried out 1 and 3 months after the end of treatment.EA at Zhigou (TE 6) could obviously improve clinical symptoms and colon transmission time, decrease using rate of Kaisailu and cathartics, with an effective rate of 94.4%, which was better than 61.3% in the control group (P0.0001).EA at Zhigou (TE 6) has a function of regulating qi and relaxing the bowels and it is an effective method for treatment of constipation with safety and no adverse effect.

To study the expression of E-cadherin and beta-catenin in neuroblastomas of various degrees of differentiation, and to investigate their molecular mechanisms in correlation with clinicopathologic parameters.Immunohistochemistry EnVision method was used to detect E-cadherin and beta-catenin expression in 90 paraffin-embedded tissue samples of neuroblastomas. The methylation status of CpG islands of E-cadherin promoter was investigated by MSP in 7 fresh tissue and 24 paraffin-embedded tissue samples. The mutation status of exon 3 of beta-catenin gene was studied by PCR in 7 fresh tissue samples. Statistical analysis of the data was performed by SPSS software.E-cadherin and beta-catenin were abnormally expressed in neuroblastomas in general. The expression of beta-catenin in well-differentiated neuroblastoms was markedly higher (47/70, 67.1%) than that of the poorly differentiated tumors (8/20, 40.0%). There was a markedly decreased expression of both genes in tumors with lymph node metastasis than those without. Demethylation was seen in some regions of the promoter of E-cadherin in 31 cases of nuroblatomas. PCR of the exon 3 of beta-catenin followed by DNA sequencing demonstrated rearrangements and mutations in 7 cases, including 2 cases harboring identical point mutation at gene position 27184, leading to a T--A alteration.The abnormal over-expression of E-cadherin in neuroblastomas is independent of the methylation status of their promoter sequences. The abnormal expression of beta-catenin may be related to mutational changes at exon 3 of the gene.

Conotruncal defects (CTD) is a common type of cyanotic congenital heart defects. It was shown that CTD might be produced by ablation of cardiac neural crest during early stage embryos in experimental studies. There were many kinds of genes involved and cardiac alpha-actin (CAA) was one of them. The purpose of this study was to investigate the spatial expression of CAA gene during embryonic heart development, and to explore its role in the pathogenesis of congenital heart defects.Experimental chicken embryos were subjected to cardiac neural crest ablation by using electric stimulation at 36-40 hr incubation stage. The embryos and organs of experimental and normal control groups during different developing periods were taken out, RNA was extracted by Trizol, and then reverse transcription was done. The dynamic changes of CAA mRNA expression at different development stages of embryos were assayed by fluorescent real-time PCR. The embryos and tissues at different stages were taken out, and paraffin sections were made. The localizations of CAA antibody expression in the developmental embryos were detected by immunohistochemical analysis (peroxidase-DAB coloration).(1) The expression of CAA gene was detected at early embryo development, and increased subsequently to a stable level. Its expression was mainly limited to heart site, and could be increased along with the maturation of the cardiac muscle. There was no expression or little trace expression in liver, brain, and stomach. (2) There was a significantly low level of CAA gene expression on days 2-7 of chicken embryos whose cardiac neural crest were ablated in comparison with normal controls (P = 0.013). The level of CAA gene expression was also down-regulated on days 7, 9 and 15 of embryonic cardiac tissues (P = 0.029).CAA gene is closely associated with heart development, its expression was adjusted by cardiac neural crest, and its dysfunction may be an important factor leading to congenital heart defects.

Playing a central role in hepatic fibrosis, hepatic stellate cell (HSC) has made itself the major target of research. The limited supply of HSC, however, can not meet the ever growing need of experiment. Establishment and identification of novel immortalized HSC line thus may be urgently required.Primary HSCs were isolated from a normal adult male Sprague-Dawley rat by in situ perfusion with collagenase IV and pronase E, and then were purified by single-step density gradient centrifugation with nycodenz. Once they reached total activation in culture, a new immortalized myofibroblast-like HSC line was established through cellular cloning. Its characteristics were identified by means of immunocytochemical staining, light microscopy, transmission electron microscopy, and growth curve analysis.The novel HSC line, termed HSC-PQ, had a doubling time of about 75 hours in the Dulbecco's modified Eagle medium (DMEM) containing 20% fetal bovine serum. Most of the main morphological characteristics of the differentiated primary HSC could be detected in HSC-PQ cell, while functional features of activated HSC such as alpha-smooth muscle actin, desmin, collagen type I, collagen type III, fibronectin, laminin and other extracellular matrix proteins could also be found in it except for collagen type IV. In contrast, fat droplets and autofluorescence of vitamin A disappeared in the HSC-PQ line. This cell line had been maintained in culture for over 30 passages and more than 1 year with little alternation in biological characteristics.A new rat HSC line (HSC-PQ) has been successfully established. It consistently retains the characteristics of activated primary HSC, and has proved to be immortalized.

Objectives: The aim of this study was to verify the accuracy of using myocardial contrast echocardiography (MCE), to quantify regional myocardial blood flow (MBF), and to evaluate myocardial viability in comparison to that measured by radiolabeled microsphere and pathologic examination. Methods: Epicardial MCE was obtained in five myocardial ischemic dogs with constant microbubble intravenous infusion. After the video intensity (VI, y) versus pulsing interval plots derived from each myocardial pixel were fitted to an exponential function: y = A(1 − e−βt), the MBF was calculated as the product of A (microvascular cross-sectional area or myocardial blood volume) and β (mean myocardial microbubble velocity). The MBF was also obtained by radiolabeled microsphere method. Results: The MBF derived by radiolabeled microsphere method in the normal, ischemic, and infarcted region was 1.5 ± 0.3, 0.7 ± 0.3, and 0.3 ± 0.2 ml/min per gram, respectively; P < 0.01. The product of A and β in those regions was 52.5 ± 15.1, 24.4 ± 3.9, and 3.7 ± 3.8, respectively; P < 0.01. The normalized product of A and β correlated well with normalized MBF (r = 0.81, P = 0.001). Conclusion: Our initial study demonstrated that MCE has an ability to assess MBF in ischemic myocardium in the experimental model. It may provide a potential capability to detect viable myocardium noninvasively after total persistent coronary occlusion in the clinical setting. (ECHOCARDIOGRAPHY, Volume 21, July 2004)

This study investigates the influence of hepatic arterial occlusion (HAO) on blood perfusion of transplanted cancer in rat's liver, and the expression of vascular endothelial growth factor (VEGF) and matrix metalloproteinase-1 (MMP-1) and explores the mechanisms involved in transcatheter arterial embolization (TAE)-induced metastasis of liver cancer preliminarily.Walker 256 carcinosarcoma was transplanted into rat's liver to create the liver cancer model. Hepatic arterial ligation (HAL) was used to block the hepatic arterial blood supply and simulate TAE. Rats bearing tumor were divided into three groups: control, laparotomy control, and HAL groups. Blood perfusion of tumor was analyzed by a Hoechst 33342 labeling assay. The level of serum VEGF was assayed by ELISA; and the expression of VEGF and MMP-1 mRNA was detected by in situ hybridization.Two days after HAL, the number of Hoechst 33342 labeled cells which represent the blood perfusion of the tumor directly and hypoxia of tumor indirectly in the HAL group decreased significantly compared with that in the control group (329.1+/-29.3 vs. 383.6+/-19.2, P0.01). The level of serum VEGF in the HAL group increased significantly compared with that of the control group (92.5+/-43.9 pg/mL vs. 54.9+/-19.3 pg/mL, P0.05). The expression of VEGF and MMP-1 mRNA in the tumor tissue of the HAL group increased significantly compared with that of the control and the laparotomy control groups (P0.05). The blood perfusion data of the tumor, represented by number of Hoechst 33342 labeled cells, showed an inverse correlation with the expression of VEGF mRNA in tumor tissue (P0.05). While 6 days after HAL, the blood perfusion of tumor in HAL group decreased and the expression of VEGF and MMP-1 increased only slightly, not significantly, compared with that in the control group.In conclusion, blockage of hepatic arterial blood supply results in transient decreased blood perfusion and increased expression of metastasis-associated genes VEGF and MMP-1 of transplanted liver cancer in rats. Decreased blood perfusion and hypoxia may be the major reason for up-regulated expression of VEGF. Better understanding of the mechanisms involved with TAE-induced metastasis may lead to the enhancement of the long-term effects of TAE for liver cancer.

AIM: Ets1 proto-oncogene is a transcription factor involved in the activation of several genes of tumor invasion and metastasis. We aimed to determine the relationship between the extent and intensity of Ets1 expression and patients’ clinicopathological factors in gastric carcinoma. METHODS: Immunohistochemical analysis was performed for gastric tumor paraffin-embedded sections, followed by image analysis. RESULTS: Ets1 was not expressed in the normal gastric epithelium and its surrounding cells. The percentage of Ets1 expressing cells detected increased significantly in both epithelial tumor and stromal cells from high T classification, lymph node metastasis positive, clinical advanced-stage groups (P

To observe if octreotide can augment the effects of hepatic arterial occlusion for transplanted cancer in rat's liver.Walker 256 carcinosarcoma was transplanted into rat's liver to create the liver cancer model. Hepatic arterial ligation was used to block the hepatic arterial blood supply. Rats bearing tumor were divided into three groups: control group, HAL (hepatic arterial ligation) group, and HAL plus octreotide group. Change of tumor volume and tumor growth inhibiting rate after therapy were evaluated. Hoechst 33342 labeling assay was used to analyze the blood perfusion of tumor (the labeled cells' number presenting blood perfusion). Expression of vascular endothelial growth factor and matrix metalloproteinase-1 mRNA was detected by in situ hybridization, and the level of serum vascular endothelial growth factor was assayed by ELISA.Six days after hepatic arterial ligation, the mean tumor volume in control group, HAL group, and HAL plus octreotide group was 0.103 +/- 0.043 cm3, 0.030 +/- 0.018 cm3, and 0.016 +/- 0.005 cm3, respectively. The tumor volume in the two behind groups was smaller than that in the control group (P0.01), and the tumor growth-inhibiting rate was 70.8%, and 84.5%, respectively. Compared with the HAL group, the tumor volume in HAL plus octreotide group decreased significantly (P0.05). Hoechst 33342 labeled cells' number in control group, HAL group, and HAL plus octreotide group was 369.7 +/- 30.2, 344.1 +/- 26.0, and 323.2 +/- 40.4, respectively. The number in HAL combined with octreotide group decreased significantly compared with that in control group (P0.05), which suggested that the blood perfusion of tumor in HAL plus octreotide group decreased significantly. The expression of vascular endothelial growth factor and matrix metalloprotenase-1 mRNA decreased slightly, but not significantly in HAL plus octreotide group compared with that in HAL group (P0.05).The results suggest that octreotide can promote the effects of hepatic arterial occlusion therapy for transplanted cancer in rat's liver. Decreasing the blood perfusion of tumor after hepatic arterial blockage maybe one of its major mechanisms.

To investigate the influence of hepatic arterial blockage on blood perfusion of transplanted cancer in rat liver and the expression of vascular endothelial growth factor (VEGF) and matrix metalloproteinase-1 (MMP-1), and to explore the mechanisms involved in transarterial embolization (TAE)-induced metastasis of liver cancer preliminarily.Walker 256 carcinosarcoma was transplanted into rat liver to establish the liver cancer model. Hepatic arterial ligation (HAL) was used to block the hepatic arterial blood supply and simulate TAE. Blood perfusion of tumor in control, laparotomy control, and HAL group was analyzed by Hoechst 33342 labeling assay, the serum VEGF level was assayed by ELISA, the expression of VEGF and MMP-1 mRNA was detected by in situ hybridization.Two days after HAL, the number of Hoechst 33342 labeled cells which represent the blood perfusion of tumor directly and hypoxia of tumor indirectly in HAL group decreased significantly compared with that in control group (329+/-29 vs 384+/-19, P0.01). The serum VEGF level in the HAL group increased significantly as against that of the control group (93 ng.L(-1)+/-44 ng.L(-1) vs 55 ng.L(-1)+/-19 ng.L(-1), P0.05). The expression of VEGF and MMP-1 mRNA in the tumor tissue of the HAL group increased significantly compared with that of the control and the laparotomy control groups (P0.05). The blood perfusion data of the tumor, represented by the number of Hoechst 33342 labeled cells, showed a good linear inverse correlation with the serum VEGF level (r=-0.606, P0.05) and the expression of VEGF mRNA in the tumor tissue ( r =-0.338, P0.01).Blockage of hepatic arterial blood supply results in decreased blood perfusion and increased expression of metastasis-associated genes VEGF and MMP-1 of transplanted liver cancer in rats. Decreased blood perfusion and hypoxia may be the major cause of up-regulated expression of VEGF.