Fast detection and structural identification of carbocations on zeolites by dynamic nuclear polarization enhanced solid-state NMR

Acidic zeolites are porous aluminosilicates used in a wide range of industrial processes such as adsorption and catalysis. The formation of carbocation intermediates plays a key role in reactivity, selectivity and deactivation in heterogeneous catalytic processes. However, the observation and determination of carbocations remain a significant challenge in heterogeneous catalysis due to the lack of selective techniques of sufficient sensitivity to detect their low concentrations. Here, we combine 13C isotopic enrichment and efficient dynamic nuclear polarization magic angle spinning nuclear magnetic resonance spectroscopy to detect carbocations in zeolites. We use two dimensional 13C-13C through-bond correlations to establish their structures and 29Si-13C through-space experiments to quantitatively probe the interaction between multiple surface sites of the zeolites and the confined hydrocarbon pool species. We show that a range of various membered ring carbocations are intermediates in the methanol to hydrocarbons reaction catalysed by different microstructural β-zeolites and highlight that different reaction routes for the formation of both targeted hydrocarbon products and coke exist. These species have strong van der Waals interaction with the zeolite framework demonstrating that their accumulation in the channels of the zeolites leads to deactivation. These results enable understanding of deactivation pathways and open up opportunities for the design of catalysts with improved performances.

GLI-1 facilitates the EMT induced by TGF-β1 in gastric cancer

OBJECTIVE

To explore how GLI-1 affects the EMT induced by TGF-β1 in gastric cancer.

MATERIALS AND METHODS

Following 24 hours of culture of SGC-7901 cells in presence of TGF-β1, we observed the changes in morphology as well as mRNA and protein expressions of GLI-1, E-cadherin and Vimentin by RT-PCR and Western blot. Transwell assay was conducted to evaluate the changes in invasion ability of SGC-7901 cells. Then, SGC-7901 cells were co-treated with TGF-β1 and GANT 61, and changes of the above indexes were also detected using the corresponding methods.

RESULTS

In presence of TGF-β1, EMT was initiated in SGC-7901 cells EMT with increased cell invasion ability, and the mRNA and protein expressions of E-cadherin were downregulated, while those of the GLI-1 and Vimentin were upregulated. Conversely, the co-treatment of TGF-β1 and GANT 61 suppressed the increased cell invasion ability induced only by TGF-β1, and the changes in mRNA and protein expressions of these factors were abolished.

CONCLUSIONS

We found that GLI-1 facilitates the EMT induced by TGF-β1 in SGC-7901 cells, which may serve as a potential target in developing the clinical treatment of gastric cancer.

Measurement of the Branching Fraction For the Semileptonic Decay D^{0(+)}→π^{-(0)}μ^{+}ν_{μ} and Test of Lepton Flavor Universality

Using a data sample corresponding to an integrated luminosity of 2.93  fb^{-1} taken at a center-of-mass energy of 3.773 GeV with the BESIII detector operated at the BEPCII collider, we perform an analysis of the semileptonic decays D^{0(+)}→π^{-(0)}μ^{+}ν_{μ}. The branching fractions of D^{0}→π^{-}μ^{+}ν_{μ} and D^{+}→π^{0}μ^{+}ν_{μ} are measured to be (0.272±0.008_{stat}±0.006_{syst})% and (0.350±0.011_{stat}±0.010_{syst})%, respectively, where the former is of much improved precision compared to previous results and the latter is determined for the first time. Using these results along with previous BESIII measurements of D^{0(+)}→π^{-(0)}e^{+}ν_{e}, we calculate the branching fraction ratios to be R^{0}≡B_{D^{0}→π^{-}μ^{+}ν_{μ}}/B_{D^{0}→π^{-}e^{+}ν_{e}}=0.922±0.030_{stat}±0.022_{syst} and R^{+}≡B_{D^{+}→π^{0}μ^{+}ν_{μ}}/B_{D^{+}→π^{0}e^{+}ν_{e}}=0.964±0.037_{stat}±0.026_{syst}, which are compatible with the theoretical expectation of lepton flavor universality within 1.7σ and 0.5σ, respectively. We also examine the branching fraction ratios in different four-momentum transfer square regions, and find no significant deviations from the standard model predictions.

First Observation of the Doubly Charmed Baryon Decay Ξ_{cc}^{++}→Ξ_{c}^{+}π^{+}

The doubly charmed baryon decay Ξ_{cc}^{++}→Ξ_{c}^{+}π^{+} is observed for the first time, with a statistical significance of 5.9σ, confirming a recent observation of the baryon in the Λ_{c}^{+}K^{-}π^{+}π^{+} final state. The data sample used corresponds to an integrated luminosity of 1.7  fb^{-1}, collected by the LHCb experiment in pp collisions at a center-of-mass energy of 13 TeV. The Ξ_{cc}^{++} mass is measured to be 3620.6±1.5(stat)±0.4(syst)±0.3(Ξ_{c}^{+})  MeV/c^{2} and is consistent with the previous result. The ratio of branching fractions between the decay modes is measured to be [B(Ξ_{cc}^{++}→Ξ_{c}^{+}π^{+})×B(Ξ_{c}^{+}→pK^{-}π^{+})]/[B(Ξ_{cc}^{++}→Λ_{c}^{+}K^{-}π^{+}π^{+})×B(Λ_{c}^{+}→pK^{-}π^{+})]=0.035±0.009(stat)±0.003(syst).

Mean standardized uptake value (SUVmean) and global hepatic glycolysis as potential imaging markers reflecting hepatic functional capacity: evidence from 18F-FDG PET/CT

BACKGROUND

Hepatic cirrhosis caused by hepatic steatosis and hepatitis is irreversible. Early and non-invasive diagnosis of these diffuse hepatopathies calls for possible imaging markers. The purpose of this study was to explore the changes in global hepatic glucose metabolism following hepatic steatosis, hepatitis, or cirrhosis on ¹⁸F-2-fluoro-2-D-deoxyglucose-positron emission tomography (¹⁸F-FDG PET)/computed tomography (CT).

METHODS

A total of 178 subjects (51 healthy controls, 41 patients with hepatic steatosis, 50 patients with chronic hepatitis, and 36 patients with hepatic cirrhosis) were recruited, and their hepatic ¹⁸F-FDG PET/CT images were reviewed retrospectively. The hepatic volume (HV; cm³), mean standardized uptake value (SUV_mean) in the global liver, and accordingly, global hepatic glycolysis (GHG; cm³) were measured. SPSS 19.0 was used for statistical analysis with ANOVA and LSD t-tests, and p <0.05 was considered statistically significant.

RESULTS

Statistical differences were observed in SUV_mean among the hepatic steatosis group (2.44 ± 0.40), hepatitis group (2.47 ±0 .37), control group (2.23 ± 0.42), and hepatic cirrhosis group (2.01 ± 0.36) except between the steatosis group and hepatitis group. Statistical differences were observed in GHG among the hepatic steatosis group (2,918.44 ± 962.67), hepatitis group (2,466.66 ± 668.33), control group (2,230.46 ± 549.47), and hepatic cirrhosis group (1,693.81 ± 666.21) except between the hepatitis group and control group.

CONCLUSIONS

SUV_mean, together with GHG, can reflect hepatic functional capacity, which can be regarded as potential imaging markers in assessing diffuse hepatopathies. HIPPOKRATIA 2018, 22(4): 162-166.

miR-155 accelerates proliferation of mouse hepatocytes during liver regeneration by directly targeting SOCS1

Liver regeneration after two-thirds partial hepatectomy (PH) is a clinically significant repair process for restoring proper liver architecture. Although microRNA-155 (miR-155) has been found to serve as a crucial microRNA regulator that controls liver cell function and proliferation, little is known about its specific role in the regenerating liver. Using a mouse model with miR-155 overexpression or miR-155 knockout, we investigated the molecular mechanisms of miR-155 in liver regeneration. We found a marked induction of miR-155 in C57BL/6 mice after PH. Furthermore, RL-m155 mice showed enhanced liver regeneration as a result of accelerated progression of hepatocytes into the cell cycle, mainly through an increase in cyclin levels. However, proliferation of hepatocytes was delayed in miR-155-deficient livers. Expression of suppressor of cytokine signaling 1 (SOCS1) was dramatically downregulated in the process of liver regeneration, and enhancement of SOCS1 contributed to impaired proliferation of hepatocytes. Additionally, in vitro and in vivo experiments showed that adenovirus- or adeno-associated virus-mediated overexpression of SOCS1 attenuated improved liver regeneration induced by miR-155 overexpression. Our study shows that miR-155 is a pro-proliferative regulator in liver regeneration by facilitating the cell cycle and directly targeting SOCS1. NEW & NOTEWORTHY Our findings suggest a microRNA-155 (miR-155)-mediated positive regulation pattern in liver regeneration. A series of in vivo and in vitro studies showed that miR-155 upregulation enhanced partial hepatectomy-induced proliferation of hepatocytes by promoting the cell cycle without inducing DNA damage or apoptosis. Suppressor of cytokine signaling 1, a target gene of miR-155, antagonized the proliferation-promoting effect of miR-155. Therefore, pharmacological intervention targeting miR-155 may be therapeutically beneficial in various liver diseases.

Recent Advances of Plasmonic Nanoparticles and their Applications

In the past half-century, surface plasmon resonance in noble metallic nanoparticles has been an important research subject. Recent advances in the synthesis, assembly, characterization, and theories of traditional and non-traditional metal nanostructures open a new pathway to the kaleidoscopic applications of plasmonics. However, accurate and precise models of plasmon resonance are still challenging, as its characteristics can be affected by multiple factors. We herein summarize the recent advances of plasmonic nanoparticles and their applications, particularly regarding the fundamentals and applications of surface plasmon resonance (SPR) in Au nanoparticles, plasmon-enhanced upconversion luminescence, and plasmonic chiral metasurfaces.

Liquid-crystal-loaded chiral metasurfaces for reconfigurable multiband spin-selective light absorption

Light absorption plays a key role in numerous photonic devices. In this work, we theoretically demonstrate that multiband circularly polarized light can be spin-selectively absorbed with a single-layered metasurface. The difference of absorption efficiency between left- and right-handed circularly polarized light can reach 40%. This giant chiroptical effect originates from different plasmonic resonances induced by the incident circularly polarized light with opposite spin states. Furthermore, by integrating the metasurface with nematic liquid crystals, the spin-selective absorption and the chirality can be dynamically reconfigured via applying a bias voltage. The advantageous features of being multiband-absorptive, backplane-free and reconfigurable make our proposed liquid-crystal-loaded chiral metasurfaces potentially useful for various photonic applications.

[Network pharmacology of flavonoids in Sophora alopecuroides]

The aim of this paper was to investigate the potential pharmacological effect of flavonoids in Sophora alopecuroides by network pharmacology. This study predicted the potential targets of 11 flavonoids of S. alopecuroides with help of reversed pharmacophore matching target recognition service platform (PharmMapper). The pathway information was acquired from DAVID and KEGG databases. Cytoscape software was used to construct the "ingredient-target-pathway" network of flavonoids active components of S. alopecuroides. The flavonoids active components of S. alopecuroides play anti-inflammatory, blood sugar regulating and other pharmacological effects by regulating 62 targets (such as INSR，KDR，MET) and intervening 44 pathways, such as B cell receptor signaling pathway, insulin signaling pathway, neurotrophin signaling pathway, and T cell receptor signaling pathway. In this study, the mechanism of "muti components-multitargets-multiple pathway" of flavonoids was studied. It reflects the multi-components, multi-targets and multiple pathway features of traditional Chinese medicine. Meanwhile, it provides a scientific basis for the elucidation the mechanism of S. alopecuroides as a medicine, and the development and utilization resources of S. alopecuroides.

Photo-induced luminescence degradation in Ce, Yb co-doped yttrium aluminum garnet phosphors

Photon-induced luminescence degradation of Ce, Yb co-doped yttrium aluminum garnet phosphors with different Yb concentrations under 457 nm irradiation is studied for the first time, to the best of our knowledge. The degradation behavior is more significant in nano-phosphors prepared via the solgel method, compared with bulkier samples prepared via solid-state reaction. Photoluminescence intensity of Ce³⁺ ions experiences a drop after initial illumination, due to photoionization of Ce³⁺ ions, whereas the down-converted luminescence of Yb³⁺ ions remains relatively stable. Co-doping Yb³⁺ contributes to the luminescence drop of Ce³⁺ with the excessive Yb³⁺ ions serving as additional electron traps. The results are in support of a charge transfer process.

A simple and fast quantitative analysis of quinolizidine alkaloids and their biosynthetic precursor, lysine, in Sophora alopecuroides by hydrophilic interaction chromatography coupled with triple-quadrupole tandem mass spectroscopy

INTRODUCTION

Different parts of Sophora alopecuroides L. (Fabaceae) have historically been used in traditional Chinese medicine for the treatment of dysentery and enteritis. This plant is also utilised as an important resource for industrial preparation of quinolizidine alkaloidal pharmaceuticals.

OBJECTIVE

Establish a reliable, simple and fast analytical method for the quantitative determination of the quinolizidine-type alkaloids and extend understanding of the metabolism of quinolizidine-type alkaloids in S. alopecuroides.

METHODS

Hydrophilic interaction chromatography coupled with triple-quadrupole tandem mass spectrometry (HILIC-TQ-MS/MS) in multiple-reaction monitoring (MRM) mode were used to determine seven quinolizidine-type alkaloids and their biosynthetic precursor, lysine, in S. alopecuroides.

RESULTS

A good separation was obtained on an ultra high-performance liquid chromatography (UHPLC) amide column within 7 min. The overall limits of detection (LODs) were between 1.13 and 2.81 ng/ml, and limits of quantitation (LOQs) were between 3.80 and 8.48 ng/ml. The developed method was successfully applied to 21 samples of S. alopecuroides. The seeds had the highest concentration of alkaloids among the different plant parts. Oxymatrine and oxysophocarpine were the two most abundant alkaloids in all of the different parts and at different phenological growth stages. The contents of quinolizidine alkaloids showed correlations with lysine.

CONCLUSION

A rapid and sensitive analytical method was established for the simultaneous determination of seven quinolizidine-type alkaloids and their biosynthetic precursor, lysine, in S. alopecuroides; the content of lysine may be used as a marker to predict alkaloid production.

Urinary tract infection control in intensive care patients

This retrospective study tried to find the potential approach for reducing the urinary tract infection (UTI) in intensive care patients (ICPs) among adult population.In total, 96 eligible ICP cases were included. Of these, 48 cases received 10% povidone-iodine and were assigned to the intervention group, while the other 48 cases underwent sterile water, and were assigned to the control group for the prevention of catheter-associated UTI before indwelling urinary catheter insertion in ICP. The primary outcome was the occurrence of an UTI after the indwelling catheter. The secondary outcome was the identification of pathogenic species. The outcomes were assessed after catheter removed.After catheter removal, the occurrence of an UTI did not differ significantly between the 2 groups (P = .34). In addition, no significant differences regarding the pathogenic species were detected between the 2 groups (Escherichia coli, P = .73; Candida albicans, P = .57; Enterococcus, P = .65; Proteus mirabilis, P = .50; Citrobacter, P = .50; Klebsiella pneumoniae, P = .57).The use of 10% povidone-iodine may not help reducing UTI in ICP.

Measurement of Angular and CP Asymmetries in D^{0}→π^{+}π^{-}μ^{+}μ^{-} and D^{0}→K^{+}K^{-}μ^{+}μ^{-} Decays

The first measurements of the forward-backward asymmetry of the dimuon pair (A_{FB}), the triple-product asymmetry (A_{2ϕ}), and the charge-parity-conjugation asymmetry (A_{CP}), in D^{0}→π^{+}π^{-}μ^{+}μ^{-} and D^{0}→K^{+}K^{-}μ^{+}μ^{-} decays are reported. They are performed using data from proton-proton collisions collected with the LHCb experiment from 2011 to 2016, corresponding to a total integrated luminosity of 5  fb^{-1}. The asymmetries are measured to be A_{FB}(D^{0}→π^{+}π^{-}μ^{+}μ^{-})=(3.3±3.7±0.6)%, A_{2ϕ}(D^{0}→π^{+}π^{-}μ^{+}μ^{-})=(-0.6±3.7±0.6)%, A_{CP}(D^{0}→π^{+}π^{-}μ^{+}μ^{-})=(4.9±3.8±0.7)%, A_{FB}(D^{0}→K^{+}K^{-}μ^{+}μ^{-})=(0±11±2)%, A_{2ϕ}(D^{0}→K^{+}K^{-}μ^{+}μ^{-})=(9±11±1)%, A_{CP}(D^{0}→K^{+}K^{-}μ^{+}μ^{-})=(0±11±2)%, where the first uncertainty is statistical and the second systematic. The asymmetries are also measured as a function of the dimuon invariant mass. The results are consistent with the standard model predictions.

Measurement of the Ω_{c}^{0} Baryon Lifetime

We report a measurement of the lifetime of the Ω_{c}^{0} baryon using proton-proton collision data at center-of-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of 3.0  fb^{-1} collected by the LHCb experiment. The sample consists of about 1000  Ω_{b}^{-}→Ω_{c}^{0}μ^{-}ν[over ¯]_{μ}X signal decays, where the Ω_{c}^{0} baryon is detected in the pK^{-}K^{-}π^{+} final state and X represents possible additional undetected particles in the decay. The Ω_{c}^{0} lifetime is measured to be τ_{Ω_{c}^{0}}=268±24±10±2  fs, where the uncertainties are statistical, systematic, and from the uncertainty in the D^{+} lifetime, respectively. This value is nearly four times larger than, and inconsistent with, the current world-average value.

Observation of a New Ξ_{b}^{-} Resonance

From samples of pp collision data collected by the LHCb experiment at sqrt[s]=7, 8 and 13 TeV, corresponding to integrated luminosities of 1.0, 2.0 and 1.5  fb^{-1}, respectively, a peak in both the Λ_{b}^{0}K^{-} and Ξ_{b}^{0}π^{-} invariant mass spectra is observed. In the quark model, radially and orbitally excited Ξ_{b}^{-} resonances with quark content bds are expected. Referring to this peak as Ξ_{b}(6227)^{-}, the mass and natural width are measured to be m_{Ξ_{b}(6227)^{-}}=6226.9±2.0±0.3±0.2  MeV/c^{2} and Γ_{Ξ_{b}(6227)^{-}}=18.1±5.4±1.8  MeV/c^{2}, where the first uncertainty is statistical, the second is systematic, and the third, on m_{Ξ_{b}(6227)^{-}}, is due to the knowledge of the Λ_{b}^{0} baryon mass. Relative production rates of the Ξ_{b}(6227)^{-}→Λ_{b}^{0}K^{-} and Ξ_{b}(6227)^{-}→Ξ_{b}^{0}π^{-} decays are also reported.

Measurement of the Absolute Branching Fraction of the Inclusive Decay Λ_{c}^{+}→Λ+X

Based on an e^{+}e^{-} collision data sample corresponding to an integrated luminosity of 567  pb^{-1} taken at the center-of-mass energy of sqrt[s]=4.6  GeV with the BESIII detector, we measure the absolute branching fraction of the inclusive decay Λ_{c}^{+}→Λ+X to be B(Λ_{c}^{+}→Λ+X)=(38.2_{-2.2}^{+2.8}±0.9)% using the double-tag method, where X refers to any possible final state particles. In addition, we search for direct CP violation in the charge asymmetry of this inclusive decay for the first time, and obtain A_{CP}≡[B(Λ_{c}^{+}→Λ+X)-B(Λ[over ¯]_{c}^{-}→Λ[over ¯]+X)]/[B(Λ_{c}^{+}→Λ+X)+B(Λ[over ¯]_{c}^{-}→Λ[over ¯]+X)]=(2.1_{-6.6}^{+7.0}±1.6)%, a statistically limited result with no evidence of CP violation.

Measurement of the Lifetime of the Doubly Charmed Baryon Ξ_{cc}^{++}

The first measurement of the lifetime of the doubly charmed baryon Ξ_{cc}^{++} is presented, with the signal reconstructed in the final state Λ_{c}^{+}K^{-}π^{+}π^{+}. The data sample used corresponds to an integrated luminosity of 1.7  fb^{-1}, collected by the LHCb experiment in proton-proton collisions at a center-of-mass energy of 13 TeV. The Ξ_{cc}^{++} lifetime is measured to be 0.256_{-0.022}^{+0.024}(stat)±0.014(syst)  ps.

Observation of a_{0}^{0}(980)-f_{0}(980) Mixing

We report the first observation of a_{0}^{0}(980)-f_{0}(980) mixing in the decays of J/ψ→ϕf_{0}(980)→ϕa_{0}^{0}(980)→ϕηπ^{0} and χ_{c1}→a_{0}^{0}(980)π^{0}→f_{0}(980)π^{0}→π^{+}π^{-}π^{0}, using data samples of 1.31×10^{9}  J/ψ events and 4.48×10^{8}  ψ(3686) events accumulated with the BESIII detector. The signals of f_{0}(980)→a_{0}^{0}(980) and a_{0}^{0}(980)→f_{0}(980) mixing are observed at levels of statistical significance of 7.4σ and 5.5σ, respectively. The corresponding branching fractions and mixing intensities are measured and the constraint regions on the coupling constants, g_{a_{0}K^{+}K^{-}} and g_{f_{0}K^{+}K^{-}}, are estimated. The results improve the understanding of the nature of a_{0}^{0}(980) and f_{0}(980).

Structure-Activity Relationship of Novel and Selective Biaryl-Chroman GPR40 AgoPAMs

A series of biaryl chromans exhibiting potent and selective agonism for the GPR40 receptor with positive allosteric modulation of endogenous ligands (AgoPAM) were discovered as potential therapeutics for the treatment of type II diabetes. Optimization of physicochemical properties through modification of the pendant aryl rings resulted in the identification of compound AP5, which possesses an improved metabolic profile while demonstrating sustained glucose lowering.

Precision Study of η^{'}→γπ^{+}π^{-} Decay Dynamics

Using a low background data sample of 9.7×10^{5}  J/ψ→γη^{'}, η^{'}→γπ^{+}π^{-} events, which are 2 orders of magnitude larger than those from the previous experiments, recorded with the BESIII detector at BEPCII, the decay dynamics of η^{'}→γπ^{+}π^{-} are studied with both model-dependent and model-independent approaches. The contributions of ω and the ρ(770)-ω interference are observed for the first time in the decays η^{'}→γπ^{+}π^{-} in both approaches. Additionally, a contribution from the box anomaly or the ρ(1450) resonance is required in the model-dependent approach, while the process specific part of the decay amplitude is determined in the model-independent approach.

Abnormalities of hair structure and skin histology derived from CRISPR/Cas9-based knockout of phospholipase C-delta 1 in mice

BACKGROUND

Hairless mice have been widely applied in skin-related researches, while hairless pigs will be an ideal model for skin-related study and other biomedical researches because of the similarity of skin structure with humans. The previous study revealed that hairlessness phenotype in nude mice is caused by insufficient expression of phospholipase C-delta 1 (PLCD1), an essential molecule downstream of Foxn1, which encouraged us to generate PLCD1-deficient pigs. In this study, we plan to firstly produce PLCD1 knockout (KO) mice by CRISPR/Cas9 technology, which will lay a solid foundation for the generation of hairless PLCD1 KO pigs.

METHODS

Generation of PLCD1 sgRNAs and Cas 9 mRNA was performed as described (Shao in Nat Protoc 9:2493-2512, 2014). PLCD1-modified mice (F0) were generated via co-microinjection of PLCD1-sgRNA and Cas9 mRNA into the cytoplasm of C57BL/6J zygotes. Homozygous PLCD1-deficient mice (F1) were obtained by intercrossing of F0 mice with the similar mutation.

RESULTS

PLCD1-modified mice (F0) showed progressive hair loss after birth and the genotype of CRISPR/Cas9-induced mutations in exon 2 of PLCD1 locus, suggesting the sgRNA is effective to cause mutations that lead to hair growth defect. Homozygous PLCD1-deficient mice (F1) displayed baldness in abdomen and hair sparse in dorsa. Histological abnormalities of the reduced number of hair follicles, irregularly arranged and curved hair follicles, epidermal hyperplasia and disturbed differentiation of epidermis were observed in the PLCD1-deficient mice. Moreover, the expression level of PLCD1 was significantly decreased, while the expression levels of other genes (i.e., Krt1, Krt5, Krt13, loricrin and involucrin) involved in the differentiation of hair follicle were remarkerably increased in skin tissues of PLCD1-deficient mice.

CONCLUSIONS

In conclusion, we achieve PLCD1 KO mice by CRISPR/Cas9 technology, which provide a new animal model for hair development research, although homozygotes don't display completely hairless phenotype as expected.

Precision Measurement of the e^{+}e^{-}→Λ_{c}^{+}Λ[over ¯]_{c}^{-} Cross Section Near Threshold

The cross section of the e^{+}e^{-}→Λ_{c}^{+}Λ[over ¯]_{c}^{-} process is measured with unprecedented precision using data collected with the BESIII detector at sqrt[s]=4574.5, 4580.0, 4590.0 and 4599.5 MeV. The nonzero cross section near the Λ_{c}^{+}Λ[over ¯]_{c}^{-} production threshold is cleared. At center-of-mass energies sqrt[s]=4574.5 and 4599.5 MeV, the higher statistics data enable us to measure the Λ_{c} polar angle distributions. From these, the Λ_{c} electric over magnetic form-factor ratios (|G_{E}/G_{M}|) are measured for the first time. They are found to be 1.14±0.14±0.07 and 1.23±0.05±0.03, respectively, where the first uncertainties are statistical and the second are systematic.

Gambogic Acid Efficiently Kills Stem-Like Colorectal Cancer Cells by Upregulating ZFP36 Expression

BACKGROUND/AIMS

Gambogic acid (GA), the main active compound of Gamboge hanburyi, has been reported to be a potential novel antitumor drug. Whether GA inhibits putative cancer stem cells (CSCs), which are considered to be the major cause of cancer treatment failure, remains largely unknown. This study investigated whether GA inhibits the CSCs of colorectal cancer (CRC) and its possible mechanisms.

METHODS

We performed CCK8 and tumor sphere formation assays, percentage analysis of both side population and CD133+CD44+ cells, and the detection of stem cells markers, in order to assess the role of GA in inhibiting the stem celllike features of CRC. An mRNA microarray was performed to identify the downstream gene affected by GA and rescue assays were performed to further clarify whether the downstream gene is involved in the GA induced decrease of the stem cell-like CRC population. CRC cells were engineered with a CSC detector vector encoding GFP and luciferase (Luc) under the control of the Nanog promoter, which were utilized to investigate the effect of GA on putative CSC in human tumor xenograft-bearing mice using in vivo bioluminescence imaging.

RESULTS

Our results showed that GA significantly reduced tumor sphere formation and the percentages of side population and CD133+CD44+ cells, while also decreasing the expression of stemness and EMT-associated markers in CRC cells in vitro. GA killed stem-like CRC cells by upregulating the expression of ZFP36, which is dependent on the inactivation of the EGFR/ ERK signaling pathway. GFP+ cells harboring the PNanog-GFP-T2A-Luc transgene exhibited CSC characteristics. The in vivo results showed that GA significantly inhibited tumor growth in nude mice, accompanied by a remarkable reduction in the putative CSC number, based on whole-body bioluminescence imaging.

CONCLUSION

These findings suggest that GA significantly inhibits putative CSCs of CRC both in vitro and in vivo by inhibiting the activation of the EGFR/ ERK/ZFP36 signaling pathway and may be an effective drug candidate for anticancer therapies.