Neuraminidases-Key Players in the Inflammatory Response after Pathophysiological Cardiac Stress and Potential New Therapeutic Targets in Cardiac Disease

Oseltamivir (Tamiflu), a Commonly Prescribed Antiviral Drug, Mitigates Hearing Loss in Mice

Hearing loss affects up to 10% of all people worldwide, but currently there is only one FDA-approved drug for its prevention in a subgroup of cisplatin-treated pediatric patients. Here, we performed an unbiased screen of 1,300 FDA-approved drugs for protection against cisplatin-induced cell death in an inner ear cell line, and identified oseltamivir phosphate (brand name Tamiflu), a common influenza antiviral drug, as a top candidate. Oseltamivir phosphate was found to be otoprotective by oral delivery in multiple established cisplatin and noise exposure mouse models. The drug conferred permanent hearing protection of 15-25 dB SPL for both female and male mice. Oseltamivir treatment reduced in mice outer hair cells death after cisplatin treatment and mitigated cochlear synaptopathy after noise exposure. A potential binding protein, ERK1/2, associated with inflammation, was shown to be activated with cisplatin treatment and reduced by oseltamivir cotreatment in cochlear explants. Importantly, the number of infiltrating immune cells to the cochleae in mice post noise exposure, were significantly reduced with oseltamivir treatment, suggesting an anti-inflammatory mechanism of action. Our results support oseltamivir, a widespread drug for influenza with low side effects, as a promising otoprotective therapeutic candidate in both cisplatin chemotherapy and traumatic noise exposure.

Sialic acid as the potential link between lipid metabolism and inflammation in the pathogenesis of atherosclerosis

In the modern world, cardiovascular diseases have a special place among the most common causes of death. Naturally, this widespread problem cannot escape the attention of scientists and researchers. One of the main conditions preceding the development of fatal cardiovascular diseases is atherosclerosis. Despite extensive research into its pathogenesis and possible prevention and treatment strategies, many gaps remain in our understanding of this disease. For example, the concept of multiple low-density lipoprotein modifications was recently stated, in which desialylation is of special importance. Apart from this, sialic acids are known to be important contributors to processes such as endothelial dysfunction and inflammation, which in turn are major components of atherogenesis. In this review, we have collected information on sialic acid metabolism, analyzed various aspects of its implication in atherosclerosis at different stages, and provided an overview of the role of particular groups of enzymes responsible for sialic acid metabolism in the context of atherosclerosis.

LRP-1 Binds Fibrinogen in a Sialylation-Dependent Manner: A Quartz Crystal Microbalance Study

Cardiovascular disease (CVD) is the leading cause of mortality in the United States. Atherosclerosis, the dominant condition leading to CVD, is characterized by fibrofatty plaque formation. Fibrinogen, an important clotting factor, has been known to promote atherogenesis as it retains the ability to trigger smooth muscle cell proliferation, localize in areas crucial to plaque progression, and bind both platelets and leukocytes. Yet, these consequences can be suppressed through anti-inflammatory receptors like LRP-1─an endocytic receptor part of the LDLR family responsible for the endocytosis of cell debris and protein degradation products. However, the continual progression of atherosclerosis in many patients indicates that such clearance mechanisms, deemed efferocytosis, are impaired during atherosclerosis. Using the quartz crystal microbalance with dissipation monitoring (QCM-D) as a platform to investigate receptor-ligand interactions, we identify fibrinogen to be a ligand of LRP-1 and characterize its binding with LRP-1. By examining a key player in atherosclerosis development─the effect of sialidase on receptor efficacy─we found that the desialylation of LRP-1 reduces its ability to bind fibrinogen. Protein docking simulations highlighted the N-terminus portion of fibrinogen's α domain as the LRP-1 docking site. The sialylated O-linked glycans at T894 and T935 have the potential to mediate direct binding of LRP-1 to fibrinogen and support the tertiary structure of LRP-1. These phenomena are important in showing a probable cause of defective efferocytosis that occurs readily during atherosclerosis.

Determination of Oseltamivir in Human Plasma by HPLC-MS/MS

A procedure for the determination of oseltamivir in human plasma by high-performance liquid chromatography( tandem mass spectrometry (HPLC-MS/MS) was proposed and validated. Arapid and easy-to-use method of liquid(liquid extraction with ethyl acetate using venlafaxine as an internal standard was used during sample preparation. The addition of benzoic acid to aqueous acetonitrile solutions of the analyte was shown to prevent its oxidative degradation. The detection limit and limit of quantitation were 0.08 and 0.30 ng/mL, respectively; the calibration range, 0.3-200 ng/mL (R ² = 0.9937); the total analysis time, 3.2 min. The within- and between-run accuracy ranged from 97 to 105%. The precision was <10%. The proposed procedure was characterized by selective determination of the analyte, the absence of significant matrix effects, the ability to dilute samples with high analyte concentrations, and satisfactory extraction recovery (≥89%). The analyte was stable when stored in plasma samples (4 h at room temperature, 31 d at (80°C, after three freeze(thaw cycles) and extracts under autosampler storage conditions (24 h at 15°C). The procedure was successfully used for oseltamivir quantitation in actual plasma samples from healthy volunteers obtained during a bioequivalence study of the new generic drug.