Single-holed cobalt - nitrogen - carbon hollow structure with oxidase-mimicking activity for the chemiluminescence determination of ß - galactosidase activity.

A single-holed cobalt - nitrogen - carbon (Co - N - C) hollow structure nanozyme has been fabricated by in situ growth of zeolitic imidazolate framework (ZIF - 67) on the polystyrene (PS) sphere and following treatment by high-temperature carbonization. The Co - N - C nanostructure mimics the activity of oxidase and can activate O2 into reactive oxygen species (ROS), giving a remarkable enhancement on the chemiluminescence (CL) signal of luminol - O2 reaction. The Co - N - C oxidase mimic has further been exploited in the biosensing field by the determination of the activity of ß - galactosidase (ß - gal). The CL method for ß - gal activity has a linear range of 0.5 mU·L-1 to 5.0 U·L-1, a detection limit of 0.167 mU·L-1, and the precision of 3.1% (5.0 U·L-1, n = 11). This method has been employed to assess inhibitor screening of ß - gal and determine activity of ß - gal in spiked human serum samples.

Pseudomonas Acts as a Reservoir of Novel Tigecycline Resistance Efflux Pump tmexC6D6-toprJ1b and tmexCD-toprJ Variants.

Several variants of the plasmid-carried tigecycline resistance gene cluster, tmexCD-toprJ, have been identified. This study characterized another novel variant, tmexC6D6-toprJ1b, located on the chromosome of environmental-origin Pseudomonas mendocina. TMexC6D6-TOprJ1 mediates resistance to multiple drugs, including tigecycline. The promoter activity of tmexC6D6-toprJ1b and negative transcriptional repression by the upstream regulator tnfxB6 are crucial for the expression of tmexC6D6-toprJ1b. tmexC6D6-toprJ1b was found in the plasmids or chromosomes of different Pseudomonas species from six countries. Two genetic backgrounds, class 1 integrons and int-carrying integrase units, were found adjacent to the tmexC6D6-toprJ1b gene cluster and might mediate the transfer of this novel efflux pump gene cluster in Pseudomonas. Further phylogenetic analysis revealed Pseudomonas as the major reservoir of tmexCD-toprJ variants, warranting closer monitoring in the future. IMPORTANCE Tigecycline is one of the treatment options for serious infections caused by multidrug-resistant bacteria, and tigecycline resistance has gained extensive attention. The emergence of a transferable tigecycline resistance efflux pump gene cluster, tmexCD-toprJ, severely challenged the efficiency of tigecycline. In this study, we identified another novel tmexCD-toprJ variant, tmexC6D6-toprJ1b, which could confer resistance to multiple classes of antibiotics, including tigecycline. Although tmexC6D6-toprJ1b was found only in Pseudomonas species, tmexC6D6-toprJ1b might spread to Enterobacteriaceae hosts via mobile genetic elements resembling those of other tmexCD-toprJ variants, compromising the therapeutic strategies. Meanwhile, novel transferable tmexCD-toprJ variants are constantly emerging and mostly exist in Pseudomonas spp., indicating Pseudomonas as the important hidden reservoir and origin of tmexCD-toprJ variants. Continuous monitoring and investigations of tmexCD-toprJ are urgent to control its spread.

Optimization of Benzamide Derivatives as Potent and Orally Active Tubulin Inhibitors Targeting the Colchicine Binding Site.

Targeting the colchicine binding site on tubulin is a promising strategy to develop cancer therapeutics. Herein, we describe our systematic structure-activity relationship studies of benzamide derivatives that lead to an identification of a potent and orally active tubulin inhibitor 48, which occupied all three zones of the colchicine binding site in the X-ray co-crystal structure, inhibited tubulin polymerization, promoted mitotic blockade and apoptosis, and exhibited significant antiproliferative activities against various cancer cell lines. Compound 48 demonstrated favorable pharmacokinetic profiles, robust in vivo antitumor efficacies, and acceptable safety profiles. Furthermore, 48 overcame drug resistance in the paclitaxel-resistant A549 xenograft model. Collectively, 48 has been advanced into further preclinical evaluation for the development of next-generation microtubule-targeting drugs.

A novel PI3K inhibitor XH30 suppresses orthotopic glioblastoma and brain metastasis in mice models.

Glioblastoma is carcinogenesis of glial cells in central nervous system and has the highest incidence among primary brain tumors. Brain metastasis, such as breast cancer and lung cancer, also leads to high mortality. The available medicines are limited due to blood-brain barrier. Abnormal activation of phosphatidylinositol 3-kinases (PI3K) signaling pathway is prevalent in glioblastoma and metastatic tumors. Here, we characterized a 2-amino-4-methylquinazoline derivative XH30 as a potent PI3K inhibitor with excellent anti-tumor activity against human glioblastoma. XH30 significantly repressed the proliferation of various brain cancer cells and decreased the phosphorylation of key proteins of PI3K signaling pathway, induced cell cycle arrest in G1 phase as well. Additionally, XH30 inhibited the migration of glioma cells and blocked the activation of PI3K pathway by interleukin-17A (IL-17A), which increased the migration of U87MG. Oral administration of XH30 significantly suppressed the tumor growth in both subcutaneous and orthotopic tumor models. XH30 also repressed tumor growth in brain metastasis models of lung cancers. Moreover, XH30 reduced IL-17A and its receptor IL-17RA in vivo. These results indicate that XH30 might be a potential therapeutic drug candidate for glioblastoma migration and brain metastasis.

The effect of targeted nursing on the quality of sleep and life in lung cancer patients undergoing chemotherapy.

OBJECTIVE: To explore the effect of targeted nursing on the quality of sleep and life in lung cancer patients undergoing chemotherapy. METHODS: This study was conducted in 88 lung cancer patients who underwent chemotherapy. According to the random number table, these patients were assigned to the control group (n=44) and the experimental group (n=44). In the control group, patients received routine nursing. Meanwhile, patients in the experimental group received both routine nursing and targeted nursing. The quality of sleep score, quality of life score, psychological state-related score, and visual analogue scale (VAS) score on admission and 1 week after discharge were compared between the two groups. RESULTS: There were no differences in the quality of sleep score, quality of life score, psychological state-related score, and VAS score between the two groups of patients on admission (all P>0.05). Compared with those on admission, the quality of sleep score, quality of life score, psychological state-related score, and VAS score in both groups 1 week after discharge were declined (all P<0.05). Additionally, the changes in the experimental group were much bigger than those in the control group (all P<0.001). Satisfaction in nursing in the experimental group was higher than that in the control group (P<0.05). CONCLUSION: Targeted nursing can improve the quality of sleep, quality of life, psychological state, and satisfaction in nursing in lung cancer patients undergoing chemotherapy.

A novel orally active microtubule destabilizing agent S-40 targets the colchicine-binding site and shows potent antitumor activity.

The tubulin colchicine binding site has been recognized as an attractive drug target to combat cancer, but none of the candidate drugs have been approved for medical treatment. We recently identified a structurally distinct small molecule S-40 as an oral potent tubulin destabilizing agent. Crystal structure analysis of S-40 in a complex with tubulin at a resolution of 2.4 Å indicated that S-40 occupies all 3 zones in the colchicine pocket with interactions different from known microtubule inhibitors, presenting unique effects on assembly and curvature of tubulin dimers. S-40 overcomes paclitaxel resistance and lacks neurotoxicity, which are the main obstacles limiting clinical applications of paclitaxel. Moreover, S-40 harbors the ability to inhibit growth of cancer cell lines as well as patient-derived organoids, induce mitotic arrest and cell apoptosis. Xenograft mouse models of human prostate cancer DU145, non-small cell lung cancer NCI-H1299 and paclitaxel-resistant A549 were strongly restrained without apparent side effects by S-40 oral administration once daily. These findings provide evidence for the development of S-40 as the next generation of orally effective microtubule inhibitors for cancer therapy.

An Appraisal of Lung Nodules Automatic Classification Algorithms for CT Images.

Lung cancer is one of the most deadly diseases around the world representing about 26% of all cancers in 2017. The five-year cure rate is only 18% despite great progress in recent diagnosis and treatment. Before diagnosis, lung nodule classification is a key step, especially since automatic classification can help clinicians by providing a valuable opinion. Modern computer vision and machine learning technologies allow very fast and reliable CT image classification. This research area has become very hot for its high efficiency and labor saving. The paper aims to draw a systematic review of the state of the art of automatic classification of lung nodules. This research paper covers published works selected from the Web of Science, IEEEXplore, and DBLP databases up to June 2018. Each paper is critically reviewed based on objective, methodology, research dataset, and performance evaluation. Mainstream algorithms are conveyed and generic structures are summarized. Our work reveals that lung nodule classification based on deep learning becomes dominant for its excellent performance. It is concluded that the consistency of the research objective and integration of data deserves more attention. Moreover, collaborative works among developers, clinicians, and other parties should be strengthened.

DNA recognition patterns of the multi-zinc-finger protein CTCF: a mutagenesis study.

CCCTC-binding factor (CTCF) is a zinc-finger protein, serving an important part in the genome architecture as well as some biochemical processes. Over 70,000 CTCF binding DNA sites have been detected genome-wide, and most anchors of chromatin loops are demarcated with the CTCF binding. Various protein or RNA molecules interact with DNA-bound CTCF to conduct different biological functions, and potentially the interfaces between CTCF and its cofactors can be targets for drug development. Here we identify the effective region of CTCF in DNA recognition, which defines the exposed CTCF surface feature for the interaction of cofactors. While the zinc-finger region contributes the most in DNA association, its binding affinity varies based on different DNA sequences. To investigate the effectiveness of individual zinc-fingers, the key residues are mutated to inactivate the DNA binding ability, while the finger configuration and the spacing between fingers are preserved. The strategy is proved to be successful, while clear differences are observed in the DNA binding affinities among the 11 finger mutants and the result is consistent to previous studies in general. With the help of inactivated finger mutants, we identify the ineffective fingers and the dominant effective fingers, which form distinctive patterns on different DNA targets.

A Case Study on Attribute Recognition of Heated Metal Mark Image Using Deep Convolutional Neural Networks.

Heated metal mark is an important trace to identify the cause of fire. However, traditional methods mainly focus on the knowledge of physics and chemistry for qualitative analysis and make it still a challenging problem. This paper presents a case study on attribute recognition of the heated metal mark image using computer vision and machine learning technologies. The proposed work is composed of three parts. Material is first generated. According to national standards, actual needs and feasibility, seven attributes are selected for research. Data generation and organization are conducted, and a small size benchmark dataset is constructed. A recognition model is then implemented. Feature representation and classifier construction methods are introduced based on deep convolutional neural networks. Finally, the experimental evaluation is carried out. Multi-aspect testings are performed with various model structures, data augments, training modes, optimization methods and batch sizes. The influence of parameters, recognitio efficiency and execution time are also analyzed. The results show that with a fine-tuned model, the recognition rate of attributes metal type, heating mode, heating temperature, heating duration, cooling mode, placing duration and relative humidity are 0.925, 0.908, 0.835, 0.917, 0.928, 0.805 and 0.92, respectively. The proposed method recognizes the attribute of heated metal mark with preferable effect, and it can be used in practical application.

Identification of a Novel Liver X Receptor Agonist that Regulates the Expression of Key Cholesterol Homeostasis Genes with Distinct Pharmacological Characteristics.

Activation of liver X receptor (LXR) is associated with cholesterol metabolism and anti-inflammatory processes, which makes it beneficial to antiatherosclerosis therapy. Nevertheless, existing agonists that target LXR, for example TO901317, are related to unwanted side effects. In the present study, using a screening method we identified IMB-808, which displayed potent dual LXRα/ß agonistic activity. In vitro, IMB-808 effectively increased the expressing quantity of genes related to reverse cholesterol transport process as well as those associated with cholesterol metabolism pathway in multiple cell lines. Additionally, IMB-808 remarkably promoted cholesterol efflux from RAW264.7 as well as THP-1 macrophage cells and reduced cellular lipid accumulation accordingly. Interestingly, compared with TO901317, IMB-808 almost did not increase the expressing quantity of genes related to lipogenesis in HepG2 cells, which indicated that IMB-808 could exhibit fewer internal lipogenic side effects with a characteristic of selective LXR agonist. Furthermore, in comparison with the full LXR agonist TO901317, IMB-808 recruits coregulators differently and possesses a distinct predictive binding pattern for the LXR ligand-binding domain. In summary, our study demonstrated that IMB-808 could act as an innovative partial LXR agonist that avoids common lipogenic side effects, providing insight for the design of novel LXR modulators. Our data indicate that this compound might be used as a promising therapeutic agent for the prospective treatment of atherosclerosis in the future.

The Ikaros family of zinc-finger proteins.

Ikaros represents a zinc-finger protein family important for lymphocyte development and certain other physiological processes. The number of family members is large, with alternative splicing producing various additional isoforms from each of the five homologous genes in the family. The functional forms of Ikaros proteins could be even more diverse due to protein-protein interactions readily established between family members. Emerging evidence suggests that targeting Ikaros proteins is feasible and effective in therapeutic applications, although the exact roles of Ikaros proteins remain elusive within the intricate regulatory networks in which they are involved. In this review we collect existing knowledge as to the functions, regulatory pathways, and molecular mechanisms of this family of proteins in an attempt to gain a better understanding through the comparison of activities and interactions among family members.

E17110 promotes reverse cholesterol transport with liver X receptor ß agonist activity in vitro.

Liver X receptor (LXR) plays an important role in reverse cholesterol transport (RCT), and activation of LXR could reduce atherosclerosis. In the present study we used a cell-based screening method to identify new potential LXRß agonists. A novel benzofuran-2-carboxylate derivative was identified with LXRß agonist activity: E17110 showed a significant activation effect on LXRß with an EC50 value of 0.72 µmol/L. E17110 also increased the expression of ATP-binding cassette transporter A1 (ABCA1) and G1 (ABCG1) in RAW264.7 macrophages. Moreover, E17110 significantly reduced cellular lipid accumulation and promoted cholesterol efflux in RAW264.7 macrophages. Interestingly, we found that the key amino acids in the LXRß ligand-binding domain had distinct interactions with E17110 as compared to TO901317. These results suggest that E17110 was identified as a novel compound with LXRß agonist activity in vitro via screening, and could be developed as a potential anti-atherosclerotic lead compound.

TRANSCRIPTION. Structures of the RNA polymerase-σ54 reveal new and conserved regulatory strategies.

Transcription by RNA polymerase (RNAP) in bacteria requires specific promoter recognition by σ factors. The major variant σ factor (σ(54)) initially forms a transcriptionally silent complex requiring specialized adenosine triphosphate-dependent activators for initiation. Our crystal structure of the 450-kilodalton RNAP-σ(54) holoenzyme at 3.8 angstroms reveals molecular details of σ(54) and its interactions with RNAP. The structure explains how σ(54) targets different regions in RNAP to exert its inhibitory function. Although σ(54) and the major σ factor, σ(70), have similar functional domains and contact similar regions of RNAP, unanticipated differences are observed in their domain arrangement and interactions with RNAP, explaining their distinct properties. Furthermore, we observe evolutionarily conserved regulatory hotspots in RNAPs that can be targeted by a diverse range of mechanisms to fine tune transcription.

Molecular basis of nucleotide-dependent substrate engagement and remodeling by an AAA+ activator.

Binding and hydrolysis of ATP is universally required by AAA+ proteins to underpin their mechano-chemical work. Here we explore the roles of the ATPase site in an AAA+ transcriptional activator protein, the phage shock protein F (PspF), by specifically altering the Walker B motif sequence required in catalyzing ATP hydrolysis. One such mutant, the E108Q variant, is defective in ATP hydrolysis but fully remodels target transcription complexes, the RNAP-σ(54) holoenzyme, in an ATP dependent manner. Structural analysis of the E108Q variant reveals that unlike wild-type protein, which has distinct conformations for E108 residue in the ATP and ADP bound forms, E108Q adapts the same conformation irrespective of nucleotide bound. Our data show that the remodeling activities of E108Q are strongly favored on pre-melted DNA and engagement with RNAP-σ(54) using ATP binding can be sufficient to convert the inactive holoenzyme to an active form, while hydrolysis per se is required for nucleic acid remodeling that leads to transcription bubble formation. Furthermore, using linked dimer constructs, we show that RNAP-σ(54) engagement by adjacent subunits within a hexamer are required for this protein remodeling activity while DNA remodeling activity can tolerate defective ATP hydrolysis of alternating subunits.

Drug resistance confounding prion therapeutics.

There is not a single pharmaceutical that halts or even slows any neurodegenerative disease. Mounting evidence shows that prions cause many neurodegenerative diseases, and arguably, scrapie and Creutzfeldt-Jakob disease prions represent the best therapeutic targets. We report here that the previously identified 2-aminothiazoles IND24 and IND81 doubled the survival times of scrapie-infected, wild-type mice. However, mice infected with Rocky Mountain Laboratory (RML) prions, a scrapie-derived strain, and treated with IND24 eventually exhibited neurological dysfunction and died. We serially passaged their brain homogenates in mice and cultured cells. We found that the prion strain isolated from IND24-treated mice, designated RML[IND24], emerged during a single passage in treated mice. Although RML prions infect both the N2a and CAD5 cell lines, RML[IND24] prions could only infect CAD5 cells. When passaged in CAD5 cells, the prions remained resistant to high concentrations of IND24. However, one passage of RML[IND24] prions in untreated mice restored susceptibility to IND24 in CAD5 cells. Although IND24 treatment extended the lives of mice propagating different prion strains, including RML, another scrapie-derived prion strain ME7, and chronic wasting disease, it was ineffective in slowing propagation of Creutzfeldt-Jakob disease prions in transgenic mice. Our studies demonstrate that prion strains can acquire resistance upon exposure to IND24 that is lost upon passage in mice in the absence of IND24. These data suggest that monotherapy can select for resistance, thus intermittent therapy with mixtures of antiprion compounds may be required to slow or stop neurodegeneration.

[C2H2 zinc-finger recognition of biomolecules].

C2H2 zinc-finger motif presents in 3% of proteins that are encoded in the human genome, and has the abilities to recognize DNA, RNA and protein. With nearly 3 decades of efforts, the mechanisms of zinc-finger mediated biomolecule recognitions have been studied to various extents. Zinc-finger binds into the major groove of DNA double helix, establishes an one-to-one recognition format between DNA bases and certain amino acids in a zinc-finger, and achieves specificity based on DNA sequences. While RNA molecules show a large variety in their structures, zinc-finger recognizes RNA through the collected information of specially displayed bases and special backbone folding. Initial studies have been performed on zinc-finger mediated protein-protein interactions. Existing data indicate multiple recognition modes. The studies on molecular mechanism have supported the development of engineered zinc-fingers, which have been introduced into applications. For its wide existence, large functional diversity and potential in translational applications, zinc-finger deserves a systematic study in every aspect.

Biaryl amides and hydrazones as therapeutics for prion disease in transgenic mice.

The only small-molecule compound demonstrated to substantially extend survival in prion-infected mice is a biaryl hydrazone termed "Compd B" (4-pyridinecarboxaldehyde,2-[4-(5-oxazolyl)phenyl]hydrazone). However, the hydrazone moiety of Compd B results in toxic metabolites, making it a poor candidate for further drug development. We developed a pharmacophore model based on diverse antiprion compounds identified by high-throughput screening; based on this model, we generated biaryl amide analogs of Compd B. Medicinal chemistry optimization led to multiple compounds with increased potency, increased brain concentrations, and greater metabolic stability, indicating that they could be promising candidates for antiprion therapy. Replacing the pyridyl ring of Compd B with a phenyl group containing an electron-donating substituent increased potency, while adding an aryl group to the oxazole moiety increased metabolic stability. To test the efficacy of Compd B, we applied bioluminescence imaging (BLI), which was previously shown to detect prion disease onset in live mice earlier than clinical signs. In our studies, Compd B showed good efficacy in two lines of transgenic mice infected with the mouse-adapted Rocky Mountain Laboratory (RML) strain of prions, but not in transgenic mice infected with human prions. The BLI system successfully predicted the efficacies in all cases long before extension in survival could be observed. Our studies suggest that this BLI system has good potential to be applied in future antiprion drug efficacy studies.

[The anti-aging effect of EPO and the preliminary probe into its mechanisms].

OBJECTIVE: To study whether erythropoietin ( EPO) has the anti-aging effect and the mechanisms of how it effects. METHODS: 5% D-galactose hypodermic injection for 6 weeks to establish the aging model. Divided rats into 5 groups randomly: the normal control (group A), the aging model (group B), the low dosage (1 000 U/ (kg x d)) of recombinant human erythropoietin (rhEPO) intervene (group C), the middle dosage (3 000 U/(kg x d)) of rhEPO intervene (group D) and the high dosage (5 000 U/(kg x d)) of rhEPO intervene (group E), 10 rats in each group. Morris water maze was used to comparing the behavioral indexes. After decapitating the rats, the malonaldehyde (MDA), Na(+)-K+ ATPase, total antioxidant capacity (T-AOC) and superoxide dismutase (SOD) of brain tissue were tested. One rat from each group was selected randomly to observe the hippocampal ultramicrostructure. RESULTS: (1) Compared with group A, the learning and memory ability of group B reduced, the level of MDA, the Na(+)-K+ ATPase, T-AOC and the SOD activities of brain tissue decreased (P < 0.05), besides, a series of aging changes were observed in the hippocampal ultramicro-structure in group B. (2) Compared with group B, an improved learning and memory ability of group D, a reduced MDA content and an increased activity of Na(+)-K+ ATPase, T-AOC and the SOD activities of brain tissue in group D were also observed with a improved hippocampal ultramicro-structure. (3) The low dosage of rhEPO intervention could against the decrease of the activities of brain Na(+)-K+ ATPase, SOD of aging rat (P < 0.05), but had no significant effects on the rest of the indicators. The high dosage of rhEPO intervention had no significant improvements on various indicators of aging rats in high dosage of rhEPO intervention group was noticed (P > 0.05). CONCLUSION: The middle dosage of EPO has the anti-aging effect, and its mechanisms may be related to enhancing the antioxidant enzymes activity and increasing the antioxidant capacity.

Structural basis for the recognition and cleavage of abasic DNA in Neisseria meningitidis.

Base excision repair (BER) is a highly conserved DNA repair pathway throughout all kingdoms from bacteria to humans. Whereas several enzymes are required to complete the multistep repair process of damaged bases, apurinic-apyrimidic (AP) endonucleases play an essential role in enabling the repair process by recognizing intermediary abasic sites cleaving the phosphodiester backbone 5' to the abasic site. Despite extensive study, there is no structure of a bacterial AP endonuclease bound to substrate DNA. Furthermore, the structural mechanism for AP-site cleavage is incomplete. Here we report a detailed structural and biochemical study of the AP endonuclease from Neisseria meningitidis that has allowed us to capture structural intermediates providing more complete snapshots of the catalytic mechanism. Our data reveal subtle differences in AP-site recognition and kinetics between the human and bacterial enzymes that may reflect different evolutionary pressures.

Analyzing interactions between SSB and proteins by the use of fluorescence anisotropy.

Fluorescence anisotropy is a useful tool to detect SSB interaction with SSB binding partners. Titrating an SSB protein partner into a solution containing fluorescently labeled SSB C-terminal tail (SSB-Ct) peptide results in formation of the protein complex with molecular weights greatly higher than SSB peptide alone. Thus the tumbling of the complexes in solution is slower, and the fluorescence anisotropy (FA) signal would be increased, indicating the binding. Based on the FA binding curve, the apparent dissociation constant (K(d,app)) of the binding reaction can also be calculated.