Recommending Mobile Microblog Users via a Tensor Factorization Based on User Cluster Approach

User influence is a very important factor for microblog user recommendation in mobile social network. However, most existing user influence analysis works ignore user’s temporal features and fail to filter the marketing users with low influence, which limits the performance of recommendation methods. In this paper, a Tensor Factorization based User Cluster (TFUC) model is proposed. We firstly identify latent influential users by neural network clustering. Then, we construct a features tensor according to latent influential user’s opinion, activity, and network centrality information. Furthermore, user influences are predicted by the latent factors resulting from the temporal restrained CP decomposition. Finally, we recommend microblog users considering both user influence and content similarity. Our experimental results show that the proposed model significantly improves recommendation performance. Meanwhile, the mean average precision of TFUC outperforms the baselines with 3.4% at least

Synthesis and In Vitro Antitumor Activity of Two Mixed-Ligand Oxovanadium(IV) Complexes of Schiff Base and Phenanthroline

Two oxovanadium(IV) complexes of [VO(msatsc)(phen)], (1) (msatsc = methoxylsalicylaldehyde thiosemicarbazone, phen = phenanthroline) and its novel derivative [VO (4-chlorosatsc)(phen)], (2) (4-chlorosatsc = 4-chlorosalicylaldehyde thiosemicarbazone), have been synthesized and characterized by elemental analysis, IR, ES-MS, 1H NMR, and magnetic susceptibility measurements. Their antitumor effects on BEL-7402, HUH-7, and HepG2 cells were studied by MTT assay. The antitumor biological mechanism of these two complexes was studied in BEL-7402 cells by cell cycle analysis, Hoechst 33342 staining, Annexin V-FITC/PI assay, and detection of mitochondrial membrane potential (ΔΨm). The results showed that the growth of cancer cells was inhibited significantly, and complexes 1 and 2 mainly caused in BEL-7402 cells G0/G1 cell cycle arrest and induced apoptosis. Both 1 and 2 decreased significantly the ΔΨm, causing the depolarization of the mitochondrial membrane. Complex 2 showed greater antitumor efficiency than that of complex 1

Bismuth-Induced Inactivation of Ferric Uptake Regulator from <i>Helicobacter pylori</i>

Ferric uptake regulator (Fur) of <i>Helicobacter pylori</i> is a global regulator that is important for bacterial colonization and survival within the gastric mucosa. <i>H. pylori</i> Fur (<i>Hp</i>Fur) is unique in its ability to regulate gene expression in both metal-bound (holo-Fur) and metal-free (apo-Fur) forms. Bismuth-based drugs are widely used for the treatment of <i>H. pylori</i> infection. However, the mechanism of action of bismuth drug was not fully understood. Recently, it has been reported that bismuth drugs could interfere with the bacterial ferric uptake pathway and inhibit bacterial growth, implying intrinsic correlation between bismuth drug and bacterial iron metabolism. Herein, we demonstrate that Bi­(III) binds to <i>Hp</i>Fur protein specifically at the physiologically important S1 site, which further leads to protein oligomerization and loss of DNA binding capability. The targeting of <i>Hp</i>Fur by bismuth drugs significantly reduced transcription levels of its regulated genes, which are crucial for bacterial physiology and metabolism. Our studies present direct evidence that perturbation of iron metabolism in <i>H. pylori</i> by bismuth might serve as one of the mechanisms for the antimicrobial activity of bismuth drugs

Targeting the Thioredoxin Reductase–Thioredoxin System from <i>Staphylococcus aureus</i> by Silver Ions

The thioredoxin system, which is composed of NADPH, thioredoxin reductase (TrxR), and thioredoxin (Trx), is one of the major disulfide reductase systems used by bacteria against oxidative stress. In particular, this reductase system is crucial for the survival of the pathogenic bacterium <i>Staphylococcus aureus</i>, which lacks a natural glutathione/glutaredoxin (Grx) system. Although silver ions and silver-containing materials have been used as antibacterial agents for centuries, the antibacterial mechanism of silver is not well-understood. Herein, we demonstrate that silver ions bind to the active sites of <i>S. aureus</i> TrxR and Trx with dissociation constants of 1.4 ± 0.1 μM and 15.0 ± 5.0 μM and stoichiometries of 1 and 2 Ag⁺ ions per protein, respectively. Importantly, silver ion binding leads to oligomerization and functional disruption of TrxR as well as Trx. Silver also depleted intracellular thiol levels in <i>S. aureus</i>, disrupting bacterial thiol-redox homeostasis. Our study provides new insights into the antibacterial mechanism of silver ions. Moreover, the Trx and TrxR system might serve as a feasible target for the design of antibacterial drugs