Dengue virus (DENV), a mosquito-borne flavivirus, is a major public health threat. The virus poses risk to 2.5 billion people worldwide and causes 50 to 100 million human infections each year. Neither a vaccine nor an antiviral therapy is currently available for prevention and treatment of DENV infection. Here, we report a previously undescribed adenosine analog, NITD008, that potently inhibits DENV both in vitro and in vivo. In addition to the 4 serotypes of DENV, NITD008 inhibits other flaviviruses, including West Nile virus, yellow fever virus, and Powassan virus. The compound also suppresses hepatitis C virus, but it does not inhibit nonflaviviruses, such as Western equine encephalitis virus and vesicular stomatitis virus. A triphosphate form of NITD008 directly inhibits the RNA-dependent RNA polymerase activity of DENV, indicating that the compound functions as a chain terminator during viral RNA synthesis. NITD008 has good in vivo pharmacokinetic properties and is biologically available through oral administration. Treatment of DENV-infected mice with NITD008 suppressed peak viremia, reduced cytokine elevation, and completely prevented the infected mice from death. No observed adverse effect level (NOAEL) was achieved when rats were orally dosed with NITD008 at 50 mg/kg daily for 1 week. However, NOAEL could not be accomplished when rats and dogs were dosed daily for 2 weeks. Nevertheless, our results have proved the concept that a nucleoside inhibitor could be developed for potential treatment of flavivirus infections.

The posttranslational modification of histone and other chromatin proteins has a well recognized but poorly defined role in the physiology of gene expression. With implications for interfering with these epigenetic mechanisms, we now report the existence of a relatively abundant secondary modification of chromatin proteins, the N 6 -formylation of lysine that appears to be uniquely associated with histone and other nuclear proteins. Using both radiolabeling and sensitive bioanalytical methods, we demonstrate that the formyl moiety of 3 -formylphosphate residues arising from 5 -oxidation of deoxyribose in DNA, caused by the enediyne neocarzinostatin, for example, acylate the N 6 -amino groups of lysine side chains. A liquid chromatography (LC)-tandem mass spectrometry (MS) method was developed to quantify the resulting N 6 -formyl-lysine residues, which were observed to be present histone acetylation ͉ oxidative stress ͉ enediyne

BackgroundThere is wide-spread human exposure to bisphenol A (BPA), a ubiquitous estrogenic endocrine disruptor that has been implicated as having potentially harmful effects on human heart health. Higher urine BPA concentrations have been shown to be associated with cardiovascular diseases in humans. However, neither the nature nor the mechanism(s) of BPA action on the heart are understood.Methodology/Principal FindingsThe rapid (<7 min) effects of BPA and 17β-estradiol (E2) in the heart and ventricular myocytes from rodents were investigated in the present study. In isolated ventricular myocytes from young adult females, but not males, physiological concentrations of BPA or E2 (10−9 M) rapidly induced arrhythmogenic triggered activities. The effects of BPA were particularly pronounced when combined with estradiol. Under conditions of catecholamine stimulation, E2 and BPA promoted ventricular arrhythmias in female, but not male, hearts. The cellular mechanism of the female-specific pro-arrhythmic effects of BPA and E2 were investigated. Exposure to E2 and/or BPA rapidly altered myocyte Ca2+ handling; in particular, estrogens markedly increased sarcoplasmic reticulum (SR) Ca2+ leak, and increased SR Ca2+ load. Ryanodine (10−7 M) inhibition of SR Ca2+ leak suppressed estrogen-induced triggered activities. The rapid response of female myocytes to estrogens was abolished in an estrogen receptor (ER) β knockout mouse model.Conclusions/SignificancePhysiologically-relevant concentrations of BPA and E2 promote arrhythmias in a female-specific manner in rat hearts; the pro-arrhythmic actions of estrogens are mediated by ERβ-signaling through alterations of myocyte Ca2+ handling, particularly increases in SR Ca2+ leak. Our study provides the first experimental evidence suggesting that exposure to estrogenic endocrine disrupting chemicals and the unique sensitivity of female hearts to estrogens may play a role in arrhythmogenesis in the female heart.

In an effort to define the prevalent DNA damage chemistry-associated chronic inflammation, we have quantified 12 DNA damage products in tissues from the SJL mouse model of nitric oxide (NO) overproduction. Using liquid chromatography-mass spectrometry/MS and immunoblot techniques, we analyzed spleen, liver and kidney from RcsX-stimulated and control mice for the level of the following adducts: the DNA oxidation products 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), guanidinohydantoin (Gh), oxazolone (Ox); 5-guanidino-4-nitroimidazole (NitroIm); spiroiminodihydantoin (Sp) and M(1)dG; the nitrosative deamination products 2'-deoxyxanthosine, 2'-deoxyoxanosine (dO), 2'-deoxyinosine and 2'-deoxyuridine and the lipid peroxidation-derived adducts 1,N(6)-etheno-deoxyadenosine and 1,N(2)-etheno-deoxyguanosine. The levels of dO, Gh, Ox, NitroIm and Sp were all below a detection limit of approximately 1 lesion per 10(7) bases. Whereas there were only modest increases in the spleens of RcsX-treated compared with control mice for the nucleobase deamination products (10-30%) and the DNA oxidation products 8-oxodG (10%) and M(1)dG (50%), there were large (3- to 4-fold) increases in the levels of 1,N(6)-etheno-deoxyadenosine and 1,N(2)-etheno-deoxyguanosine. Similar results were obtained with the liver and with an organ not considered to be a target for inflammation in the SJL mouse, the kidney. This latter observation suggests that oxidative and nitrosative stresses associated with inflammation can affect tissues at a distance from the activated macrophages responsible for NO overproduction during chronic inflammation. These results reveal the complexity of NO chemistry in vivo and support an important role for lipids in the pathophysiology of inflammation.