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Rice protein, stands out as a high-quality plant-based protein, suitable for dietary supplementation and food processing. Traditional methods, involving alkaline extraction and acid precipitation, are challenged by the extensive use of chemicals and the difficulty in desalination. This study proposed a novel separation method that utilizes ceramic membranes for direct alkali filtration, eliminating the formation of salts by acid neutralization. The membrane pore size and the operating parameters such as transmembrane pressure, cross-flow velocity, and pH were optimized to enable a high flux (>80 L m−2·h−1) and favorable protein rejection (>95 %) while permitting the removal of excess alkali. Additionally, the effects of non-protein substances, e.g., starch, present in the alkaline extract on the separation performance were explored. Subsequently, an optimized strategy for starch removal was proposed, involving the concentration of the alkali extract using an ultrafiltration membrane, followed by enzymatic hydrolysis of starch and diafiltration to eliminate the residuals of starch hydrolysates and alkali. Under stabilization of protein particles by carboxymethyl cellulose, rice protein with a uniform particle size of 25 nm and a purity of over 80 % was produced. The direct removal of alkali from alkali extracts of rice by ceramic membranes presents a promising strategy for producing rice protein with high purity and reduced aggregation degree, enabling better functionalities such as solubility than the conventional alkali-extraction and acid-precipitation method. [Display omitted] • An acid-free approach was proposed for the extraction and purification of rice protein. • Ceramic ultrafiltration membrane exhibited a high rejection of protein and a high stable flux. • Rice protein with a uniform particle size of 25 nm and a purity level exceeding 80 % was obtained. [ABSTRACT FROM AUTHOR]

Remdesivir (RDV) is the first drug approved by the FDA for clinical treatment of hospitalized patients infected with COVID-19 because it has been shown to have good antiviral activity against a variety of viruses, including Arenaviridae and Coronaviridae viral families. However, it has been reported that its clinical treatment leads to the symptoms of sick sinus syndrome such as sinus bradycardia, conduction block, and sinus arrest, but the electrophysiological mechanism of its specific cardiac adverse events is still unclear. We report complementary, experimental, studies of its electrophysiological effects. In wireless cardiac telemetry experiments in vivo and electrocardiographic studies in ex vivo cardiac preparations, RDV significantly caused sinus bradycardia, sinus atrial block, and prolongation of the QT interval in guinea pigs. Dose-dependent effects of RDV on the electrical activities of sinoatrial node (SA node) preparations of guinea pigs were characterised by multielectrode, optical RH237 voltage mapping. These revealed reversibly reduced sinoatrial conduction time (SACT), increased AP durations (APDs), and decreased the pacemaking rate of the SA node. Patch-clamp experiments showed that RDV significantly inhibited the I f current of HCN4 channels, resulting in a significant decrease in the spontaneous firing rate of SA node cells, which may underlie the development of sick sinus node syndrome. In addition, RDV significantly inhibits I Kr currents in hERG channels, leading to prolongation of the QT interval and playing a role in bradycardia. Therefore, these findings provide insights into the understanding the bradycardia effect of RDV, which may be used as basic theoretical guidance for the intervention of its adverse events, and prompt safety investigations of RDV's cardiac safety in the future., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Li, Yue, Xie and Zhang.)