Tryptophan transport gene inactivation promotes the development of antibiotic resistance in Escherichia coli.

Indole serves as a signaling molecule that could regulate different bacterial physiological processes, including antibiotic resistance through biofilm formation and drug efflux pump activity. In Escherichia coli, indole is produced through the tryptophan pathway, which involves three permeases (Mtr, AroP, and TnaB) that can transport the amino acid tryptophan. Although these permeases play distinct roles in the secretion of indole biosynthesis, their impact on multidrug resistance mediated by indole remaines unclear. This study was designed to investigate the connection between the tryptophan transport system and antibiotic resistance by constructing seven gene deletion mutants from E. coli MG1655 (wild type). Our result showed that deletion of the aroP or tnaB gene led to increased antibiotic resistance as evaluated by MICs for different antibiotics. Efflux activity test results revealed that the increased antibiotic resistance was related with the AcrAB-Tolc drug efflux pump in the mutants. The transcriptome analysis further demonstrated that decreased susceptibility to kanamycin and ampicillin in E. coli was accompanied by reduced accumulation of reactive oxygen species and decreased motility. These findings highlight the substantial influence of the tryptophan transport system on antibiotic resistance in E. coli, which is crucial for developing strategies against antibiotic resistance in bacterial infections.

Chemical exchange saturation transfer (CEST) magnetic resonance imaging (MRI) quantification of transient ischemia using a combination method of 5-pool Lorentzian fitting and inverse Z-spectrum analysis.

Background: Chemical exchange saturation transfer (CEST) is a promising method for the detection of biochemical alterations in cancers and neurological diseases. However, the sensitivity of the currently existing quantitative method for detecting ischemia needs further improvement. Methods: To further improve the quantification of the CEST signal and enhance the CEST detection for ischemia, we used a quantitative analysis method that combines an inverse Z-spectrum analysis and a 5-pool Lorentzian fitting. Specifically, a 5-pool Lorentzian simulation was conducted with the following brain tissue parameters: water, amide (3.5 ppm), amine (2.2 ppm), magnetization transfer (MT), and nuclear Overhauser enhancement (NOE; -3.5 ppm). The parameters were first calculated offline and stored as the initial value of the Z-spectrum fitting. Then, the measured Z-spectrum with the peak value set to 0 was fitted via the stored initial value, which yielded the reference Z-spectrum. Finally, the difference between the inverse of the Z-spectrum and the inverse of the reference Z-spectrum was used as the CEST definite spectrum. Results: The simulation results demonstrated that the Z-spectra of the rat brain were well simulated by a 5-pool Lorentzian fitting. Further, the proposed method detected a larger difference than did either the saturation transfer difference or the 5-pool Lorentzian fitting, as demonstrated by simulations. According to the results of the cerebral ischemia rat model, the proposed method provided the highest contrast-to-noise ratio (CNR) between the contralateral and the ipsilateral striatum under various acquisition conditions. The results indicated that the difference of fitted amplitudes generated with a 5-pool Lorentzian fitting in amide at 3.5 ppm (6.04%±0.39%; 6.86%±0.39%) was decreased in a stroke lesion compared to the contralateral normal tissue. Moreover, the difference of the residual of inversed Z-spectra in which 5-pool Lorentzian fitting was used to calculate the reference Z-spectra ( M T R R e x 5 L ) amplitudes in amide at 3.5 ppm (13.83%±2.20%, 15.69%±1.99%) was reduced in a stroke lesion compared to the contralateral normal tissue. Conclusions: M T R R e x 5 L is predominantly pH-sensitive and is suitable for detecting tissue acidosis following an acute stroke.

Liver cancer cells as the model for developing liver-targeted RNAi therapeutics.

RNAi is a sequence-specific gene regulation mechanism that involves small interfering RNAs (siRNAs). RNAi therapeutic has become a new class of precision medicine and has shown great potential in treating liver-associated diseases, especially metabolic diseases. To facilitate the development of liver-targeted RNAi therapeutics in cell model, we surveyed a panel of liver cancer cell lines for the expression of genes implicated in RNAi therapeutics including the asialoglycoprotein receptor (ASGR) and metabolic disease associated genes PCSK9, ANGPTL3, CIDEB, and LDLR. A high-content screen assay based on lipid droplet staining confirmed the involvement of PCSK9, ANGPTL3, and CIDEB in lipid metabolism in selected liver cancer cell lines. Several liver cancer cell lines have high levels of ASGR1 expression, which is required for liver-specific uptake of GalNAc-conjugated siRNA, a clinically approved siRNA delivery platform. Using an EGFP reporter system, we demonstrated Hep G2 can be used to evaluate gene knockdown efficiency of GalNAc-siRNA. Our findings pave the way for using liver cancer cells as a convenient model system for the identification and testing of siRNA drug candidate genes and for studying ASGR-mediated GalNAc-siRNA delivery in liver.

[Concentration Levels and Impact Factors of Benzene Series in Chinese Residential Building].

From December 2016 to December 2017, the concentrations of the benzene series (benzene, toluene, xylene, and ethyl-benzene) in air were analyzed in 223 residential buildings in five climatic regions of China during different seasons. The arithmetic average concentrations of benzene, toluene, xylene, and ethyl-benzene were 6.78, 17.4, 17.68, and 9.87 µg·m-3, respectively. Indoor benzene series concentrations in China were slightly higher than that in other countries; the standard limits for indoor benzene series concentrations in China are much higher than those of other countries and organizations. Among the many factors affecting the concentration of the benzene series in the rooms, the relationship between the completion time of decoration, smoking, and cooking frequency and the concentration of benzene homologues was studied. The results showed that the concentration of toluene decreased with the prolongation of decoration time, the concentration of benzene in smoking households was higher than that in non-smoking families, and there was no direct correlation between cooking frequency and indoor concentration of the benzene series. The study provides statistical data on exposure to the benzene series in decorated homes and a discussion of setting values of relevant standards.

Heat shock transcription factor 1 affects kidney tubular cell migration by regulating the TGF­ß1­Smad2/3 signaling pathway.

Cell migration is important for renal recovery from tubular cell injury. Heat shock transcription factor 1 (HSF1) is a well­studied regulatory factor that is active during acute kidney injury. HSF1 is also involved in the migration process during tumor metastasis. Therefore, we hypothesized that HSF1 may promote the recovery of renal function by affecting kidney tubular cell migration. A wound healing assay was used to examine the cell migration rate. The results demonstrated that the migration of rat kidney proximal tubular cells (RPTCs) was increased following knockdown of HSF1. In addition, the invasion ability of HSF1 knockdown RPTCs was also significantly upregulated. The present study also identified that transforming growth factor­ß1 (TGF­ß1) was highly expressed at the edge of the wound in control cells, and its expression was further increased upon knockdown of HSF1. Inhibition of TGF­ß1 signaling prevented RPTC HSF1 knockdown cell migration, suggesting that HSF1­regulated RPTC cell migration was dependent on the TGF­ß1 signaling pathway. Furthermore, phosphorylation of TGF­ß1 and Smad2/3 was induced in HSF1 knockdown cells. Together, these results suggest that HSF1 may suppress RPTC migration by inhibiting the activation of the TGF­ß1­Smad2/3 signaling pathway.

FoxO3a inhibiting expression of EPS8 to prevent progression of NSCLC: A new negative loop of EGFR signaling.

BACKGROUND: The resistance to EGF receptor (EGFR) tyrosine kinase inhibitors (TKI) is a major challenge in the treatment of non-small cell lung cancer (NSCLC). Understanding the molecular mechanisms behind resistance is therefore an important issue. Here we assessed the role of EGFR pathway substrate 8 (EPS8) and Forkhead box O 3a (FoxO3a) as potentially valuable targets in the resistance of NSCLC . METHODS: The expression levels of EPS8 and FoxO3a in patients with NSCLC (n = 75) were examined by immunohistochemistry staining, while in cells were detected by qPCR and western blot. The effects of EPS8 and FoxO3a on resistance, migration and invasion, cell cycle arrest were detected by MTT, transwell and flow cytometry, respectively. Chromatin immunoprecipitation and luciferase reporter assays were performed to determine the mechanisms of EPS8 expression and FoxO3a regulation. FINDINGS: We observed that the expression of EPS8 inversely correlated with FoxO3a in NSCLC cell lines and NSCLC patients. FoxO3a levels were significantly decreased in tumor tissues compared with para-carcinoma tissues, while EPS8 is opposite. Besides, they play reverse roles in the resistance to gefitinib, the migration and invasion abilities, the cell cycle arrest in vitro and the tumor growth in vivo. Mechanistically, FoxO3a inhibits EPS8 levels by directly binding its gene promoter and they form a negative loop in EGFR pathway. INTERPRETATION: Targeting FoxO3a and EPS8 in EGFR signaling pathway prevents the progression of NSCLC, which implied that the negative loop they formed could served as a therapeutic target for overcoming resistance in NSCLC. FUNDS: National Natural Science Foundation of China, Science and Technology Project of Henan, Outstanding Young Talent Research Fund of Zhengzhou University and the National Scholarship Fund.

3D multi-view convolutional neural networks for lung nodule classification.

The 3D convolutional neural network (CNN) is able to make full use of the spatial 3D context information of lung nodules, and the multi-view strategy has been shown to be useful for improving the performance of 2D CNN in classifying lung nodules. In this paper, we explore the classification of lung nodules using the 3D multi-view convolutional neural networks (MV-CNN) with both chain architecture and directed acyclic graph architecture, including 3D Inception and 3D Inception-ResNet. All networks employ the multi-view-one-network strategy. We conduct a binary classification (benign and malignant) and a ternary classification (benign, primary malignant and metastatic malignant) on Computed Tomography (CT) images from Lung Image Database Consortium and Image Database Resource Initiative database (LIDC-IDRI). All results are obtained via 10-fold cross validation. As regards the MV-CNN with chain architecture, results show that the performance of 3D MV-CNN surpasses that of 2D MV-CNN by a significant margin. Finally, a 3D Inception network achieved an error rate of 4.59% for the binary classification and 7.70% for the ternary classification, both of which represent superior results for the corresponding task. We compare the multi-view-one-network strategy with the one-view-one-network strategy. The results reveal that the multi-view-one-network strategy can achieve a lower error rate than the one-view-one-network strategy.

Microsphere Assisted Super-resolution Optical Imaging of Plasmonic Interaction between Gold Nanoparticles.

Conventional far-field microscopy cannot directly resolve the sub-diffraction spatial distribution of localized surface plasmons in metal nanostructures. Using BaTiO3 microspheres as far-field superlenses by collecting the near-field signal, we can map the origin of enhanced two-photon photoluminescence signal from the gap region of gold nanosphere dimers and gold nanorod dimers beyond the diffraction limit, on a conventional far-field microscope. As the angle θ between dimer's structural axis and laser polarisation changes, photoluminescence intensity varies with a cos4θ function, which agrees quantitatively with numerical simulations. An optical resolution of about λ/7 (λ: two-photon luminescence central wavelength) is demonstrated at dimer's gap region.

Controlled co-release of doxorubicin and reactive oxygen species for synergistic therapy by NIR remote-triggered nanoimpellers.

How to encapsulate and transport the payload of multiple therapeutic compounds avoiding premature leakage, and simultaneously co-release them rapidly at specific lesions still remains the major concern in clinic. Herein, we designed the UCN@mSiO2-(Azo+RB) (azobenzene groups and Rose Bengal) nanoimpellers, which used the multicolor-emission capability of the core-shell upconverting nanoparticles (UCNs) at a single excitation wavelength to co-release anticarcinogen doxorubicin (Dox) and reactive oxygen species (ROS) for combined chemotherapy and photodynamic therapy (PDT). The nanoimpeller was formed from UCN inner core, mesoporous silica shell, and light triggers Azo and RB molecules. The UCNs emitting UV/blue and green/red multiband light were used to activate the photoresponsive Azo and photosensitizer RB molecules; The mesoporous silica shell offered the possibilities to load anticancer drug and conjugate the light triggers; As there are strong charge interaction and hydrogen bonds between Dox and surface silanols of mesoporous silica, the azobenzene molecules worked as "gatekeeper" and "molecular stirrer" to precisely trap and propel the release of Dox under the external stimuli. The time-dependent drug release analysis, ROS production test and PDT test suggested that the nanoparticles may serve as a useful multifunctional nanoplatform for synergistic therapy and cancer diagnostic.

Construction of near infrared light triggered nanodumbbell for cancer photodynamic therapy.

The application of photodynamic therapy (PDT) in deep tissue has been severely restricted by the poor photosensitizers loading and tissue-penetration of visible light for exciting the photosensitizers. How to prepare a nanocarrier with high drug loading amount and remote controllability still remains the challenge. In this article, a novel drug delivery system nanodumbbell was designed. The nanodumbbell was assembled from the hydrophobic upconverting nanoparticle (UCN) core and hydrophilic polymersome shell. The "nanodumbbell" offers possibilities to overcome the problem mentioned above. The UCN core works as a transducer to convert deeply penetrating near-infrared light to visible light to activate photosensitizers zinc (II) phthalocyanine (ZnPc) for photodynamic therapy. The polymersome lipid shell is used for loading ZnPc and protecting the whole system from nonspecific absorbance or corrosion during the transportation. The nanodumbbell is appealing because it can simultaneously achieve the high loading amount of ZnPc while avoiding UCNs aggregation. The reactive oxygen species (ROS) production test and PDT test in vitro suggested that the fluorescence emitted from the UCNs can be effectively transferred to the photosensitizers to produce cytotoxic ROS. When the UCN@lipid@polymersome nanodumbbell was decorated with targeting peptide (RGD), it presented better target specificity to cells. Our data suggest that this nanoparticle may serve as a useful nanoplatform for PDT treatment in deep-cancer therapy based on upconverting mechanism.

NIR-Remote Selected Activation Gene Expression in Living Cells by Upconverting Microrods.

An NIR-controlled gene expression system based on upconverting rods (UCRs) is demonstrated. The UCRs can harvest the "biocompatible" NIR light and convert it into local UV light, resulting in cleavage of the photosensitive molecule (4-(hydroxymethyl)-3-nitrobenzoic acid, ONA) and on-demand release of gene carriers, thus realizing target gene expression at high spatial and temporal resolutions.

A UCN@mSiO2@cross-linked lipid with high steric stability as a NIR remote controlled-release nanocarrier for photodynamic therapy.

In clinics, the application of photodynamic therapy (PDT) in deep tissue is severely constrained by the limited penetration depth of visible light that was used for activating the photosensitizer (PS). In this work, a protocol of a UCN@SiO2@crosslinked lipid triple layer nanoparticle was developed successfully. The triple layer nanoparticle was assembled from the hydrophobic upconverting nanoparticle (UCN) core, the mesoporous silica middle shell and the cross-linked lipid out shell. The photosensitizer zinc phthalocyanine (ZnPc) loaded triple layer nanoparticle offers possibilities to solve the problem mentioned above. The UCN core works as a transducer to convert deeply penetrating near infrared light to visible light for activating ZnPc for photo dynamic therapy. The middle shell is used for loading ZnPc and the out shell can prevent the drug leaking effectively. The experiment results showed that with the help of the cross-linked lipid shell, the triple layer nanoparticle could prevent the drug leaking and particle aggregation. The ROS production test and PDT test suggested that the fluorescence emitted from the UCNs excited by NIR can effectively activate the photosensitizer ZnPc to generate cytotoxic ROS. The UCN@SiO2@crosslinked lipid triple layer nanoparticle modified with RGD has a much better treatment effect in cancer cells. Our data suggest that the UCN@SiO2@crosslinked lipid triple layer nanoparticle may be a useful nanoplatform for future PDT treatment in deep cancer therapy based on the upconverting mechanism.