Ionic Strength-Dependent, Reversible Pleomorphism of Recombinant Newcastle Disease Virus

ABSTRACT A genetically modified, recombinant form of Newcastle disease virus (rNDV) undergoes ionic strength-dependent changes in morphology, as observed by cryo-electron microscopy (cEM). In hypotonic solutions with ionic strengths ranging from < 0.01 to 0.02 M, rNDV virions are spherical or predominantly spherical. In isotonic and hypertonic solutions, rNDV displays pleomorphism and contains a mixed population of spherical and elongated particles, indicating that a change from spherical to elongated shape is induced with increasing salt concentration. This ionic strength-dependent transition is largely reversible, as determined by cEM. Concomitantly, we measured infectious titers of these same rNDV samples at different ionic strengths using a fluorescent focus assay (FFA). The infectivity of oncolytic rNDV was found to be independent of ionic strength, ranging from 0.01 M to approximately 0.5 M. These structural and functional observations, in combination, suggest that infectivity (and, by inference, oncolytic activity) of rNDV virions is fully maintained in their pleomorphic forms. IMPORTANCE Oncolytic viruses are being developed for cancer therapy, as they selectively target, infect, and kill cancer cells. NDV is particularly attractive because while it is pathogenic to avians (e.g., chickens), it does not cause significant viremia in humans. We have developed a genetically modified recombinant NDV (rNDV) that has much reduced pathogenicity in chickens but is highly oncolytic. The morphology of rNDV transitions from spherical at very low salt concentrations to a heterogeneous population of spherical and elongated virions in isotonic (physiologic salt concentration) and hypertonic solutions. The infectivity (cell-killing activity by infecting cells) of rNDV is unaltered by changes in salt concentration despite morphological changes. These observations are significant for purification and formulation of rNDV, as exposure to different salt concentrations may be needed. Importantly, at physiological salt concentration, relevant to clinical testing, infectivity and, therefore, oncolytic activity will not be compromised despite morphological heterogeneity.

Worth Their Salt: One Hundred Years of Hyperosmolar Therapy

In this article, we commemorate the centenary of the discovery and clinical implementation of hyperosmolar therapy for the treatment of increased intracranial pressure (ICP). Following the pioneering work of anatomists Weed and McKibben in 1919, the use of hypertonic solutions was soon adopted into clinical practice, even though the preferred hypertonic agent, route of administration, and ideas regarding the physiological mechanism by which it reduced ICP diverged. These divergent conceptions and practices have continued to surround the use of hyperosmolar therapy into present times.

Effect of osmotic drying on physicochemical properties of pansies (viola × wittrockiana)

The objective of this work was to study the effect of osmotic drying, using different hypertonic solutions (sucrose and sodium chloride), on physicochemical characteristics of pansies (Viola × wittrockiana). The same treatments were applied to lettuce to compare the behavior of flowers with other vegetables. Pansies' superhydrophobic surface structure, called papillae, increased the resistance to exchanges with hypertonic solutions. No weight loss was observed after most treatments (sucrose: between 2.2 and 6.8 %; NaCl: between -23.0 % and 1.5 %), aw maintained high values (>0.94) and monomeric anthocyanins were preserved (fresh 0.10 and 0.19 mg Cy-3glu/g fresh matter for 20%/1 h in NaCl and 60%/1 h in sucrose). When applying more drastic conditions, as sodium chloride for more than 1 hour, undesirable textural and color changes were observed. For lettuce, all treatments caused osmotic dehydration, weight loss (ranged between -9.3 to -30.3 % for 80%/1 h in sucrose and 15%/1 h in NaCl) and a reduction on aw (<0.97) and carotenoids, with sodium chloride causing more damage in visual appearance than sucrose. Therefore, immersion in osmotic solutions can be applied to lettuce but the desired effect was not achieved for pansies due to the morphological structure of the flowers' epidermis.

Efficacy of liposomal dosage forms and hyperosmolar salines in experimental pharmacotherapy of acute lung injury

Introduction: Hypertonic sodium chloride solutions and liposomal drugs with pulmotropic effect are of great interest for the treatment of acute lung injury (ALI). The results of the studies on the efficacy of hypertonic solutions and liposomes in ALI treatment are currently controversial.Materials and methods: For the experiment, liposomes with dexamethasone, N-acetylcysteine (NAC), aprotinin and dye Cyanine-7 (Cy-7) were obtained. A liposome analysis was performed by means of spectrophotometry. ALI was modeled in rats by the administration of the damaging agents into the trachea. The experimental agents were injected once intravenously after the modeling of ALI. For experimental therapy used liposomal agents, 7.5% hypertonic saline (HS) and HyperHAES solutions in the respective groups. The efficacy of the therapy was assessed by the survival of animals, functional indicators of the cardiovascular and respiratory systems, and by the lung-body ratio. The biodistribution of liposomes after intravenous administration was investigated in mice through using a fluorescent dye Cy-7. The biodistribution of liposomes with Cy-7 was assessed using bioimaging according to the fluorescence intensity of internal organs (lungs, liver, and kidneys) and blood, expressed as dye concentration according to the calibration dependence of dye concentrarion on fluorescence intensity.Results and discussion: All the studied liposomal drugs were effective for the pharmacological correction of ALI. Hypertonic solutions, unlike liposomal drugs, were less likely to prevent the development of pulmonary edema. All the studied therapeutic agents increased the survival rate of the laboratory animals with ALI. The most effective experimental agent was liposomal dexamethasone. The use of drugs in form of simple liposomes with average diameter of 350 nm provided for a higher concentration of the drug in the lungs within the first 40 minutes after intravenous administration.Conclusion: Intravenous administration of liposomal forms is promising for the pharmacotherapy of acute lung injury.