Gemcitabine (1) is a promising new anticancer agent used in pancreatic cancer. Improvement in the selective targeting of compound 1 and other cytotoxic agents to solid tumors may be enhanced by conjugation to ligands that target peripheral benzodiazepine receptors (PBRs) located on mitochondria and known to be overexpressed in human brain tumors. Development of such chemical conjugates requires selective protection on 4-NH(2), 3'-OH, and 5'-OH of compound 1. All three monoprotected and three diprotected gemcitabine derivatives (2 to 7) were synthesized in good yield by employing a single commonly used protecting reagent, di-tert-butyl dicarbonate, under different conditions. Consequently, the three mono-ligand-gemcitabine conjugates coupled at 4-NH(2), 3'-OH, and 5'-OH respectively (14 to 16) were synthesized in high yield using the PBR ligand PK11195. This selective protection/deprotection strategy offers a relatively straightforward means to modify other nucleosides.

Spamming is emerging as a key threat to Internet of Things (IoT)-based social media applications. It will pose serious security threats to the IoT cyberspace. To this end, artificial intelligence-based detection and identification techniques have been widely investigated. The literature works on IoT cyberspace can be categorized into two categories: 1) behavior pattern-based approaches; and 2) semantic pattern-based approaches. However, they are unable to effectively handle concealed, complicated, and changing spamming activities, especially in the highly uncertain environment of the IoT. To address this challenge, in this paper, we exploit the collaborative awareness of both patterns, and propose a Collaborative neural network-based Spammer detection mechanism (Co-Spam) in social media applications. In particular, it introduces multi-source information fusion by collaboratively encoding long-term behavioral and semantic patterns. Hence, a more comprehensive representation of the feature space can be captured for further spammer detection. Empirically, we implement a series of experiments on two real-world datasets under different scenario and parameter settings. The efficiency of the proposed Co-Spam is compared with five baselines with respect to several evaluation metrics. The experimental results indicate that the Co-Spam has an average performance improvement of approximately 5% compared to the baselines.

This study was designed to investigate the neuroprotective effect of intrinsic and extrinsic erythropoietin (EPO) against hypoxia/ischemia, and determine the optimal time-window with respect to the EPO-induced neuroprotection. Experiments were conducted using primary mixed neuronal/astrocytic cultures and neuron-rich cultures. Hypoxia (2%) induces hypoxia-inducible factor-1a (HIF-1a) activity followed by strong EPO expression in mixed cultures and weak expression in neuron-rich cultures as documented by both western blot and RT-PCR. Immunoreactive EPO was strongly detected in astrocytes, whereas EPOR was only detected in neurons. Neurons were significantly damaged in neuron-rich cultures but were distinctly rescued in mixed cultures. Application of recombinant human EPO (rhEPO) (0.1 U/mL) within 6 h before or after hypoxia significantly increased neuronal survival compared with no rhEPO treatment. Application of rhEPO after onset of reoxygenation achieved the maximal neuronal protection against ischemia/reperfusion injury (6 h hypoxia followed 24 h reoxygenation). Our results indicate that HIF-1a induces EPO gene released by astrocytes and acts as an essential mediator of neuroprotection, prove the protective role of intrinsic astrocytic-neuronal signaling pathway in hypoxic/ischemic injury and demonstrate an optimal therapeutic time-window of extrinsic rhEPO in ischemia/reperfusion injury in vitro. The results point to the potential beneficial effects of HIF-1a and EPO for the possible treatment of stroke. Keywords: erythropoietin, hypoxia-inducible factor-1, hypoxia/ischemia injury, neuroprotection. Erythropoietin (EPO) has emerged as a potent neuroprotectant in vivo and in vitro (Morishita et al. 1997;Bernaudin et al. 1999;Siren et al. 2001a). In the brain, EPO gene expression is regulated by the transcription factor hypoxiainducible factor-1 (HIF-1), which is activated by a variety of stressors, including hypoxia (Semenza 2000). EPO-induced neuroprotection is mediated by interaction with the cognate receptor EPOR (Chong et al. 2002;Marti 2004). The main cellular source of intrinsic EPO in the brain appears to be astrocytes (Masuda et al. 1994;Marti et al. 1996). In addition Bernaudin et al. (2000) provided direct evidence that not only astrocytes but also neurons express and produce EPO after hypoxia.However, there are no studies that compared the EPO expression levels and the neuroprotective effect between mixed neuronal/astrocytic cultures and neuron-rich cultures. In the present study, we determined EPO expression levels and its neuroprotective effect using both mixed neuronal/astrocytic cultures and neuron-rich cultures exposed to hypoxia and reoxygenation. We considered that the in vitro model of mixed culture might be more physiological than separate cultures for addressing the protective role of intrinsic astrocytic-neuronal signaling in hypoxic/ischemic injury. Furthermore, we compared neuronal survival in the presence or absence of antibodies against EPOR to examine whether neuroprotection i...

No abstract

No abstract

Background and Aims Nuclear‐located covalently closed circular DNA (cccDNA) of hepatitis B virus (HBV) is a determining factor for HBV persistence and the key obstacle for a cure of chronic hepatitis B. However, it remains unclear whether and how the host immune system senses HBV cccDNA and its biological consequences. Approach and Results Here, we demonstrated that interferon‐inducible protein 16 (IFI16) could serve as a unique innate sensor to recognize and bind to HBV cccDNA in hepatic nuclei, leading to the inhibition of cccDNA transcription and HBV replication. Mechanistically, our data showed that IFI16 promoted the epigenetic suppression of HBV cccDNA by targeting an interferon‐stimulated response element (ISRE) present in cccDNA. It is of interest that this ISRE was also revealed to play an important role in IFI16–activated type I interferon responses. Furthermore, our data revealed that HBV could down‐regulate the expression level of IFI16 in hepatocytes, and there was a negative correlation between IFI16 and HBV transcripts in liver biopsies, suggesting the possible role of IFI16 in suppressing cccDNA function under physiological conditions. Conclusions The nuclear sensor IFI16 suppresses cccDNA function by integrating innate immune activation and epigenetic regulation by targeting the ISRE of cccDNA, and IFI16 may present as a therapeutic target against HBV infection.

No abstract

Targeting intracellular PBRs is a new drug delivery strategy based on the use of low molecular weight drug conjugates that can be administered systemically. It was demonstrated under steady-state conditions that PK11195-GEM possessed a twofold enhancement in brain tumor selectivity compared to GEM alone. This type of target selectivity would allow higher tumor concentrations to be achieved in conjunction with lower drug concentrations in normal or non-target tissues.