Characterization of a novel Klebsiella pneumoniae sequence type 476 carrying both bla KPC-2 and bla IMP-4

Carbapenemase-producing Klebsiella pneumoniae has recently spread rapidly throughout China. In this study, we characterized a carbapenem-resistant K. pneumoniae isolate that produced both KPC-2 and IMP-4 type carbapenemases. A clinical isolate of K. pneumoniae, resistant to both meropenem and imipenem, was recovered from a urine sample. Antibiotic susceptibility was determined using the broth microdilution method and Etest (bioMérieux, France). Pulsed-field gel electrophoresis and multilocus sequence typing (MLST) were used for gene type analysis. bla (KPC) and the encoding genes of ESBLs and plasmid-mediated AmpC enzymes were polymerase chain reaction (PCR) amplified and sequenced. Plasmids were analyzed by transformation, enzyme restriction and Southern blot. PCR analysis revealed that the isolate was simultaneously carrying bla (KPC-2), bla (IMP-4), bla (TEM-1), and bla (OKP-B) genes. MLST assigned the isolate to a novel sequence type, ST476. bla (KPC-2)-harbouring plasmids of the isolate and comparative strains had similar EcoRI and HindIII restriction maps, while IMP-4-harbouring plasmids had variable HindIII restriction maps. Coexistence of bla (KPC-2) and bla (IMP-4) was probably due to bla (IMP-4)-harbouring plasmid transmission into KPC-2-producing K. pneumoniae (ST476). The concomitant presence of these genes is alarming and poses both therapeutic and infection control problems.

Core/shell structured NaYF4:Yb3+/Er3+/Gd+3 nanorods with Au nanoparticles or shells for flexible amorphous silicon solar cells

A simple approach for preparing near-infrared (NIR) to visible upconversion (UC) NaYF4:Yb/Er/Gd nanorods in combination with gold nanostructures has been reported. The grown UC nanomaterials with Au nanostructures have been applied to flexible amorphous silicon solar cells on the steel substrates to investigate their responses to sub-bandgap infrared irradiation. Photocurrent–voltage measurements were performed on the solar cells. It was demonstrated that UC of NIR light led to a 16-fold to 72-fold improvement of the short-circuit current under 980 nm illumination compared to a cell without upconverters. A maximum current of 1.16 mA was obtained for the cell using UC nanorods coated with Au nanoparticles under 980 nm laser illumination. This result corresponds to an external quantum efficiency of 0.14% of the solar cell. Mechanisms of erbium luminescence in the grown UC nanorods were analyzed and discussed.

Coronary CT angiography: current status and continuing challenges

Coronary CT angiography has been increasingly used in the diagnosis of coronary artery disease owing to rapid technological developments, which are reflected in the improved spatial and temporal resolution of the images. High diagnostic accuracy has been achieved with multislice CT scanners (64 slice and higher), and in selected patients coronary CT angiography is regarded as a reliable alternative to invasive coronary angiography. With high-quality coronary CT imaging increasingly being performed, patients can benefit from an imaging modality that provides a rapid and accurate diagnosis while avoiding an invasive procedure. Despite the tremendous contributions of coronary CT angiography to cardiac imaging, study results reported in the literature should be interpreted with caution as there are some limitations existing within the study design or related to patient risk factors. In addition, some attention must be given to the potential health risks associated with the ionising radiation received during cardiac CT examinations. Radiation dose associated with coronary CT angiography has raised serious concerns in the literature, as the risk of developing malignancy is not negligible. Various dose-saving strategies have been implemented, with some of the strategies resulting in significant dose reduction. The aim of this review is to present an overview of the role of coronary CT angiography on cardiac imaging, with focus on coronary artery disease in terms of the diagnostic and prognostic value of coronary CT angiography. Various approaches for dose reduction commonly recommended in the literature are discussed. Limitations of coronary CT angiography are identified. Finally, future directions and challenges with the use of coronary CT angiography are highlighted.

Multislice CT of the head and body routine scans: Are scanning protocols adjusted for paediatric patients?

PURPOSE

To investigate whether the multislice CT scanning protocols of head, chest and abdomen are adjusted according to patient's age in paediatric patients.

MATERIALS AND METHODS

Multislice CT examination records of paediatric patients undergoing head, chest and abdomen scans from three public hospitals during a one-year period were retrospectively reviewed. Patients were categorised into the following age groups: under 4 years, 5-8 years, 9-12 years and 13-16 years, while the tube current was classified into the following ranges: < 49 mA, 50-99 mA, 100-149 mA, 150-199 mA, > 200 mA and unknown.

RESULTS

A total of 4998 patient records, comprising a combination of head, chest and abdomen CT scans, were assessed, with head CT scans representing nearly half of the total scans. Age-based adjusted CT protocols were observed in most of the scans with higher tube current setting being used with increasing age. However, a high tube current (150-199 mA) was still used in younger patients (0-8 years) undergoing head CT scans. In one hospital, CT protocols remained constant across all age groups, indicating potential overexposure to the patients.

CONCLUSION

This analysis shows that paediatric CT scans are adjusted according to the patient's age in most of the routine CT examinations. This indicates increased awareness regarding radiation risks associated with CT. However, high tube current settings are still used in younger patient groups, thus, optimisation of paediatric CT protocols and implementation of current guidelines, such as age-and weight-based scanning, should be recommended in daily practice.

Ultrafast Raman laser mode-locked by nanotubes

We demonstrate passive mode-locking of a Raman fiber laser using a nanotube-based saturable absorber coupled to a net normal dispersion cavity. This generates highly chirped 500 ps pulses. These are then compressed down to 2 ps, with 1.4 kW peak power, making it a simple wavelength-versatile source for various applications.

Inhibition of β-catenin signaling by nongenomic action of orphan nuclear receptor Nur77

Dysregulation of β-catenin turnover due to mutations of its regulatory proteins including adenomatous polyposis coli (APC) and p53 is implicated in the pathogenesis of cancer. Thus, intensive effort is being made to search for alternative approaches to reduce abnormally activated β-catenin in cancer cells. Nur77, an orphan member of the nuclear receptor superfamily, has a role in the growth and apoptosis of cancer cells. Here, we reported that Nur77 could inhibit transcriptional activity of β-catenin by inducing β-catenin degradation via proteasomal degradation pathway that is glycogen synthase kinase 3β and Siah-1 independent. Nur77 induction of β-catenin degradation required both the N-terminal region of Nur77, which was involved in Nur77 ubiquitination, and the C-terminal region, which was responsible for β-catenin binding. Nur77/ΔDBD, a Nur77 mutant lacking its DNA-binding domain, resided in the cytoplasm, interacted with β-catenin, and induced β-catenin degradation, demonstrating that Nur77-mediated β-catenin degradation was independent of its DNA binding and transactivation, and might occur in the cytoplasm. In addition, we reported our identification of two digitalis-like compounds (DLCs), H-9 and ATE-i2-b4, which potently induced Nur77 expression and β-catenin degradation in SW620 colon cancer cells expressing mutant APC protein in vitro and in animals. DLC-induced Nur77 protein was mainly found in the cytoplasm, and inhibition of Nur77 nuclear export by the CRM1-dependent nuclear export inhibitor leptomycin B or Jun N-terminal kinase inhibitor prevented the effect of DLC on inducing β-catenin degradation. Together, our results demonstrate that β-catenin can be degraded by cytoplasmic Nur77 through their interaction and identify H-9 and ATE-i2-b4 as potent activators of the Nur77-mediated pathway for β-catenin degradation.

Mobilization of host stem cells enables long-term liver transplant acceptance in a strongly rejecting rat strain combination

Careful examination of liver, kidney and heart transplants in human recipients has revealed small numbers of host bone marrow derived stem cells in the graft. If the limited recipient repopulation of a donor graft that is currently observed could be facilitated, it is possible that conversion to a predominantly host phenotype would permit long-term graft function without immunosuppression. We proposed to "engineer" repopulation after transplant in a strain combination (dark agouti [DA] to Lewis green fluorescent protein+[LEW GFP+]) which rejects liver grafts strongly, a model that more closely resembles the situation in humans. Treatment on days 0, 1, 2, 3 and 7 after transplantation with low-dose (0.1 mg/kg) tacrolimus (T) designed to blunt rejection combined with plerixafor (P) to mobilize host stem cells resulted in greater than 180 days graft survival with extensive albeit spotty conversion of a small (50%) DA graft to the recipient LEW GFP+ genotype. Subsequent skin grafting revealed donor-specific graft prolongation. The T plus P treatment resulted in higher levels of Lin-Thy1+CD34+CD133+ stem cells and Foxp3+ regulatory T cells in the blood and liver at day 7. Thus, pharmacological mobilization of host stem cells sustains liver allografts by two mechanisms: repopulation of injured donor cells and regulation of the immune response.

Circadian epigenomic remodeling and hepatic lipogenesis: lessons from HDAC3

Circadian rhythms have evolved to anticipate metabolic needs across the 24-h light/dark cycle. This is accomplished by circadian expression of metabolic genes orchestrated by transcription factors through chromatin remodeling and histone modifications. Our recent genome-wide study on histone deacetylase 3 (HDAC3) in mouse liver provides novel insights into the molecular link between circadian rhythm and hepatic de novo lipogenesis. We found that liver-specific knockout of HDAC3 in adult mouse displays severe hepatic steatosis associated with enhanced de novo lipogenesis and increased expression of lipogenic genes. Genome-wide analysis (ChIP-seq) revealed a pronounced circadian pattern of HDAC3 occupancy on genes involved in lipid metabolism, which is inversely related to histone acetylation and RNA polymerase II recruitment at these sites. The cistromes of HDAC3 and its binding partner, nuclear receptor corepressor (NCoR), significantly overlap with that of Rev-erbα, a nuclear receptor directly involved in the core circadian machinery. Knockout of Rev-erbα in mouse also leads to hepatic steatosis and enhanced de novo lipogenesis. Collectively, these data suggest that the circadian epigenomic remodeling controlled by HDAC3, and largely directed by Rev-erbα, is essential for homeostasis of the lipogenic process in liver.

A study of diagnostic value of golgi protein GP73 and its genetic assay in primary hepatic carcinoma

This study aimed to investigate the diagnostic values of GP73 protein in patients' serum with primary hepatic carcinoma (PHC). Also GP73 mRNA expression level in peripheral blood mononuclear cells (PBMCs) and liver tissue between health controls and PHC patients was interrogated. Finally the role of combined detection of serum GP73 and alpha-fetoprotein (AFP) in high-risk population screening was evaluate, in an attempt to justify the new, sensitive, specific and rapid measure for the diagnosis and detection of PHC. Serum proteins of GP73 and AFP were examined in 73 patients with PHC, 13 patients with hepatic cirrhosis, 32 patients with hepatitis and 62 healthy subjects using enzyme-linked immunosorbent assay (ELISA). The relative expression levels of GP73 mRNA in PBMCs and liver tissues were examined by using SYBR Green quantitative reverse transcription polymerase chain reaction (RT-PCR) assay, calculated with the comparison of Cq value. In contrast to patients with cirrhosis and hepatitis, or healthy subjects, PHC patients had their serum GP73 and AFP significantly elevated (P < 0.05) while their PBMCs GP73 mRNA was not significantly different from those with cirrhosis and hepatitis, or healthy subjects (P > 0.05). The expression level of GP73 mRNA was significantly higher in PHC liver tissue than in normal liver tissue. The sensitivity for serum GP73 and AFP in PHC was 68.5% and 28.8%, respectively while that for the combined detection was up to 74%, justifying that the combined detection could prevent the false negative diagnosis by AFP alone and significantly improve the detection rate. As a new diagnostic biomarker of PHC, GP73 protein in serum was highly sensitive and specific. GP73 mRNA in PHC liver tissue specimens instead of whole blood could be used for the diagnosis of PHC as a tumor biomarker, whose detection was highly invasive, risky and afflicting otherwise. The combined detection of GP73 and AFP in serum effectively improved the diagnosis of PHC, in addition to the screening in high-risk population.

MicroRNA-335 acts as a metastasis suppressor in gastric cancer by targeting Bcl-w and specificity protein 1

Aberrant expression of miR-335 has been frequently reported in cancer studies, suggesting that there is a close correlation between miR-335 and cancer during its development, progression, metastasis and prognosis. The expression of miR-335 in gastric cancer and its effects are not known. Relative expression of miR-335 in 4 gastric cancer cell lines and in 70 gastric cancer tissues was confirmed by real-time quantitative reverse transcriptase-PCR compared with controls. Transwell cell migration and Matrigel invasion assay in vitro and metastasis formation assay in vivo were used to examine the effects of miR-335 expression on gastric cancer cell invasion and metastasis. The effect of miR-335 expression on gastric cancer cell proliferation was estimated by the 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay. Luciferase reporter assay and western blot were used to examine the potential target genes and related pathways. Gene silencing with small-interfering RNA was used to examine the effects of target genes on gastric cancer cell invasion. miR-335 was dramatically downregulated in gastric cancer cell lines than in the normal gastric cell line GES-1. Low expression of miR-335 was significantly associated with lymph-node metastasis, poor pT stage, poor pN stage and invasion of lymphatic vessels. Overexpression of miR-335 suppressed gastric cancer cell invasion and metastasis in vitro and in vivo, but has no significant effects on cell proliferation. Furthermore, miR-335 might suppress gastric cancer invasion and metastasis by targeting Bcl-w and specificity protein 1 (SP1). Taken together, our results provide evidence that miR-335 might function as a metastasis suppressor in gastric cancer by targeting SP1 directly and indirectly through the Bcl-w-induced phosphoinositide 3-kinase-Akt-Sp1 pathway. miR-335 showing altered expression at different stages of gastric cancer could be a target for gastric cancer therapies and could be further developed as a potential prognostic factor.

Large-scale growth of Cu2ZnSnSe4 and Cu2ZnSnSe4/Cu2ZnSnS4 core/shell nanowires

We present a fast and simple protocol for large-scale preparation of quaternary Cu(2)ZnSnSe(4) (CZTSe), as well as CZTSe/Cu(2)ZnSnS(4) (CZTS) core/shell nanowires using CuSe nanowire bundles as self-sacrificial templates. CuSe nanowire bundles were synthesized by reacting Cu(2 - x)Se nanowire bundles with sodium citrate solution. CZTSe nanowires were prepared by reacting CuSe nanowire bundles with Zn(CH(3)COO)(2) and SnCl(2) in triethylene glycol. X-ray diffraction (XRD) and selected area electron diffraction studies show that stannite CZTSe is formed. The formed CZTSe nanowire bundles have diameters of 200-400 nm and lengths of up to hundreds of micrometers. CZTSe/CZTS nanocable bundles with similar morphologies were grown by the addition of some elemental sulfur to the reaction system for growth of CZTSe bundles. The stannite CZTSe/kesterite CZTS core/shell structure of the grown nanocables was confirmed by XRD and high-resolution transmission electron microscope investigation. The influence of S/Se molar ratio in the reaction system on the crystallographic structures and optical properties of CZTSe/CZTS nanocables was studied. The obtained CZTSe/CZTS core/shell nanocable bundles show broad and enhanced optical absorption over the visible and near-infrared region, which is promising for use in photovoltaic applications.