Nucleoside Analogs with Selective Antiviral Activity against Dengue Fever and Japanese Encephalitis Viruses.

Dengue virus (DENV) and Japanese encephalitis virus (JEV) are important arthropod-borne viruses from the Flaviviridae family. DENV is a global public health problem with significant social and economic impacts, especially in tropical and subtropical areas. JEV is a neurotropic arbovirus endemic to east and southeast Asia. There are no U.S. FDA-approved antiviral drugs available to treat or to prevent DENV and JEV infections, leaving nearly one-third of the world's population at risk for infection. Therefore, it is crucial to discover potent antiviral agents against these viruses. Nucleoside analogs, as a class, are widely used for the treatment of viral infections. In this study, we discovered nucleoside analogs that possess potent and selective anti-JEV and anti-DENV activities across all serotypes in cell-based assay systems. Both viruses were susceptible to sugar-substituted 2'-C-methyl analogs with either cytosine or 7-deaza-7-fluoro-adenine nucleobases. Mouse studies confirmed the anti-DENV activity of these nucleoside analogs. Molecular models were assembled for DENV serotype 2 (DENV-2) and JEV RNA-dependent RNA polymerase replication complexes bound to nucleotide inhibitors. These models show similarities between JEV and DENV-2, which recognize the same nucleotide inhibitors. Collectively, our findings provide promising compounds and a structural rationale for the development of direct-acting antiviral agents with dual activity against JEV and DENV infections.

Depressed Immune Responses and Accelerated Splenic Apoptosis due to Experience of Food Deprivation and Inequality but not Unstable Social Status in Balb/c Mice.

OBJECTIVE(S): We aimed to show that the immune system is sensitive to the detrimental effects of inequality and social injustice, and splenic vulnerability to apoptosis may also increase. METHODS: In order of better determination of immune responses to chronic social stress, we implemented food deprivation, food intake inequality, and unstable social status (a change of cage-mate every 3 days) for a period of 14 days in 60 male Balb/c mice. At the end of this stress period, nitric oxide (NO) production by peritoneal adherent cells and the serum concentration of corticosterone were measured. Moreover, the viability of peritoneal adherent cells and spleen lymphocytes was evaluated by MTT assay. The terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay was done to reveal the TUNEL-reactive apoptotic bodies in the spleen. RESULTS: Our results showed that food deprivation and inequality caused significant changes in the apoptosis of splenic cells in comparison with the control group (p < 0.05). Moreover, the vital activities of lymphocytes and peritoneal adherent cells, as well as NO production by the latter, increased significantly (p < 0.05). However, the experience of unstable social status did not cause a further increase in the viability of lymphocytes and peritoneal adherent cells, or NO production in animals that were food-deprived or experienced inequality. Serum concentration of corticosterone in all experimental groups, except for animals that experienced unstable social status only, significantly decreased versus the control group (p < 0.05). CONCLUSIONS: The results suggest that poverty and social inequality, but not unstable social status, affect immune responses and are likely involved in the induction of splenic apoptosis in mice.

Acute sleep deprivation (ASD) and cardioprotection: Impact of ASD on oxytocin-mediated sympathetic nervous activation preceding myocardial infarction.

INTRODUCTION: This study explored how acute sleep deprivation (ASD) before myocardial ischemia influences oxytocin release from paraventricular (PVN) neurons and its correlation with sympathetic nervous system (SNS) activity post-acute sleep loss, impacting subsequent left ventricular (LV) remodeling following myocardial infarction (MI). METHODS: The study was conducted in two phases: induction of ASD, inducing MI, blood sampling, euthanizing animals and collecting their heart and brain for histological and gene expression evaluations. The animals in first and second phase were euthanized 24 h and 14 days after MI, respectively. RESULTS: Pre-MI ASD, accompanied by increased serum epinephrine levels within 24 h of MI, upregulated oxytocin and cFos expression in the PVN. Also, pre-MI ASD resulted in decreased serum PAB levels 14 days post-MI (P < 0.001). While notable echocardiographic changes were seen in MI versus sham groups, ASD demonstrated protective effects. This was evidenced by reduced infarct size, elevated TIMP1, MMP2, and MMP9 in the LV of SD + MI animals versus MI alone (P < 0.05). Additionally, histological analysis showed reduced LV fibrosis in pre-MI ASD subjects (P < 0.05). CONCLUSION: Our study supports the notion that activation of oxytocin neurons within the PVN subsequent to ASD interacts with autonomic centers in the central nervous system. This enhanced sympathetic outflow to the heart prior to MI triggers a preconditioning response, thereby mediating cardioprotection through decreased oxidative stress biomarkers and regulated extracellular matrix (ECM) turnover.

Conserved OprF as a Selective Immunogen against Pseudomonas aeruginosa.

BACKGROUND & OBJECTIVES: Due to the importance of Pseudomonas aeruginosa in severe inpatient infections and high mortality, the need for an efficient vaccine against these bacteria is increasing. In this regard, the general outer membrane porin of the most problematic microorganism P. aeruginosa, outer membrane protein F (OprF), is a good vaccine candidate. METHODS: The databank of NCBI was used to retrieve protein sequences recorded for OprF in P. aeruginosa.The current study aimed at investigating the conservation of the OprF in 150 reference sequences, clinical, and environmental strains of P. aeruginosa from different countries via bioinformatic tools.T-COFFEE and PRALINE software were used for alignment. RESULTS: Of these, 134 strains were isolated from clinical specimens and other strains from environmental samples. Evaluation of alignment by the mentioned software clearly showed that this protein was conserved. Antigenicity and grand average of hydropathicity were favorable. CONCLUSION: Conservation of OprF in all pathogenic and environmental strains of P. aeruginosa indicated that it can be considered as a good immunogen; however, the protectivity of OprF should be validated experimentally.

Post-infarct sleep disruption and its relation to cardiac remodeling in a rat model of myocardial infarction.

Sleep disruption after myocardial infarction (MI) by affecting ubiquitin-proteasome system (UPS) is thought to contribute to myocardial remodeling and progressive worsening of cardiac function. The aim of current study was to test the hypothesis about the increased risk of developing heart failure due to experience of sleep restriction (SR) after MI. Male Wistar rats (n = 40) were randomly assigned to four experimental groups: (1) Sham, (2) MI, (3) MI and SR (MI + SR) (4) Sham and SR (Sham + SR). MI was induced by permanent ligation of left anterior descending coronary artery. Twenty-four hours after surgery, animals were subjected to chronic SR paradigm. Blood sampling was performed at days 1, 8 and 21 after MI for determination of serum levels of creatine kinase-MB (CK-MB), corticosterone, malondialdehyde (MDA) and nitric oxide (NO). Finally, at 21 days after MI, echocardiographic parameters and expression of MuRF1, MaFBx, A20, eNOS, iNOS and NF-kB in the heart were evaluated. We used H&E staining to detect myocardial hypertrophy. We found out that post infarct SR increased corticosterone levels. Our results highlighted deteriorating effects of post-MI SR on NO production, oxidative stress, and echocardiographic indexes (p < 0.05). Moreover, its detrimental effects on myocardial damage were confirmed by overexpression of MuRF1, MaFBx, iNOS and NF-kB (p < 0.001) in left ventricle and downregulation of A20 and eNOS (p < 0.05). Furthermore, histological examination revealed that experience of SR after MI increased myocardial diameter as compared to Sham subjects (p < 0.05). Our data suggest that SR after MI leads to an enlargement of the heart within 21 days, marked by an increase in oxidative stress and NO production as well as an imbalance in UPS that ultimately results in cardiac dysfunction and heart failure.

Antiviral activity of silymarin against chikungunya virus.

The mosquito-borne chikungunya virus (CHIKV) causes chikungunya fever, with clinical presentations such as severe back and small joint pain, and debilitating arthritis associated with crippling pains that persist for weeks and even years. Although there are several studies to evaluate the efficacy of drugs against CHIKV, the treatment for chikungunya fever is mainly symptom-based and no effective licensed vaccine or antiviral are available. Here, we investigated the antiviral activity of three types of flavonoids against CHIKV in vitro replication. Three compounds: silymarin, quercetin and kaempferol were evaluated for their in vitro antiviral activities against CHIKV using a CHIKV replicon cell line and clinical isolate of CHIKV of Central/East African genotype. A cytopathic effect inhibition assay was used to determine their activities on CHIKV viral replication and quantitative reverse transcription PCR was used to calculate virus yield. Antiviral activity of effective compound was further investigated by evaluation of CHIKV protein expression using western blotting for CHIKV nsP1, nsP3, and E2E1 proteins. Briefly, silymarin exhibited significant antiviral activity against CHIKV, reducing both CHIKV replication efficiency and down-regulating production of viral proteins involved in replication. This study may have important consequence for broaden the chance of getting the effective antiviral for CHIKV infection.

Tick-borne viruses: a review from the perspective of therapeutic approaches.

Several important human diseases worldwide are caused by tick-borne viruses. These diseases have become important public health concerns in recent years. The tick-borne viruses that cause diseases in humans mainly belong to 3 families: Bunyaviridae, Flaviviridae, and Reoviridae. In this review, we focus on therapeutic approaches for several of the more important tick-borne viruses from these 3 families. These viruses are Crimean-Congo hemorrhagic fever virus (CCHF) and the newly discovered tick-borne phleboviruses, known as thrombocytopenia syndromevirus (SFTSV), Heartland virus and Bhanja virus from the family Bunyaviridae, tick-borne encephalitis virus (TBEV), Powassan virus (POWV), Louping-ill virus (LIV), Omsk hemorrhagic fever virus (OHFV), Kyasanur Forest disease virus (KFDV), and Alkhurma hemorrhagic fever virus (AHFV) from the Flaviviridae family. To date, there is no effective antiviral drug available against most of these tick-borne viruses. Although there is common usage of antiviral drugs such as ribavirin for CCHF treatment in some countries, there are concerns that ribavirin may not be as effective as once thought against CCHF. Herein, we discuss also the availability of vaccines for the control of these viral infections. The lack of treatment and prevention approaches for these viruses is highlighted, and we hope that this review may increase public health awareness with regard to the threat posed by this group of viruses.

Baicalin, a metabolite of baicalein with antiviral activity against dengue virus.

Baicalin, a flavonoid derived from Scutellaria baicalensis, is the main metabolite of baicalein released following administration in different animal models and human. We previously reported the antiviral activity of baicalein against dengue virus (DENV). Here, we examined the anti-DENV properties of baicalin in vitro, and described the inhibitory potentials of baicalin at different steps of DENV-2 (NGC strain) replication. Our in vitro antiviral experiments showed that baicalin inhibited virus replication at IC50 = 13.5 ± 0.08 µg/ml with SI = 21.5 following virus internalization by Vero cells. Baicalin exhibited virucidal activity against DENV-2 extracellular particles at IC50 = 8.74 ± 0.08 µg/ml and showed anti-adsorption effect with IC50 = 18.07 ± 0.2 µg/ml. Our findings showed that baicalin as the main metabolite of baicalein exerting in vitro anti-DENV activity. Further investigations on baicalein and baicalin to deduce its antiviral therapeutic effects are warranted.

Mechanical and in vitro biological performance of graphene nanoplatelets reinforced calcium silicate composite.

Calcium silicate (CaSiO3, CS) ceramic composites reinforced with graphene nanoplatelets (GNP) were prepared using hot isostatic pressing (HIP) at 1150°C. Quantitative microstructural analysis suggests that GNP play a role in grain size and is responsible for the improved densification. Raman spectroscopy and scanning electron microscopy showed that GNP survived the harsh processing conditions of the selected HIP processing parameters. The uniform distribution of 1 wt.% GNP in the CS matrix, high densification and fine CS grain size help to improve the fracture toughness by ∼130%, hardness by ∼30% and brittleness index by ∼40% as compared to the CS matrix without GNP. The toughening mechanisms, such as crack bridging, pull-out, branching and deflection induced by GNP are observed and discussed. The GNP/CS composites exhibit good apatite-forming ability in the simulated body fluid (SBF). Our results indicate that the addition of GNP decreased pH value in SBF. Effect of addition of GNP on early adhesion and proliferation of human osteoblast cells (hFOB) was measured in vitro. The GNP/CS composites showed good biocompatibility and promoted cell viability and cell proliferation. The results indicated that the cell viability and proliferation are affected by time and concentration of GNP in the CS matrix.

Synthesis, mechanical properties, and in vitro biocompatibility with osteoblasts of calcium silicate-reduced graphene oxide composites.

Calcium silicate (CaSiO3, CS) ceramics are promising bioactive materials for bone tissue engineering, particularly for bone repair. However, the low toughness of CS limits its application in load-bearing conditions. Recent findings indicating the promising biocompatibility of graphene imply that graphene can be used as an additive to improve the mechanical properties of composites. Here, we report a simple method for the synthesis of calcium silicate/reduced graphene oxide (CS/rGO) composites using a hydrothermal approach followed by hot isostatic pressing (HIP). Adding rGO to pure CS increased the hardness of the material by ∼40%, the elastic modulus by ∼52%, and the fracture toughness by ∼123%. Different toughening mechanisms were observed including crack bridging, crack branching, crack deflection, and rGO pull-out, thus increasing the resistance to crack propagation and leading to a considerable improvement in the fracture toughness of the composites. The formation of bone-like apatite on a range of CS/rGO composites with rGO weight percentages ranging from 0 to 1.5 has been investigated in simulated body fluid (SBF). The presence of a bone-like apatite layer on the composite surface after soaking in SBF was demonstrated by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The biocompatibility of the CS/rGO composites was characterized using methyl thiazole tetrazolium (MTT) assays in vitro. The cell adhesion results showed that human osteoblast cells (hFOB) can adhere to and develop on the CS/rGO composites. In addition, the proliferation rate and alkaline phosphatase (ALP) activity of cells on the CS/rGO composites were improved compared with the pure CS ceramics. These results suggest that calcium silicate/reduced graphene oxide composites are promising materials for biomedical applications.