Nonvesicular extracellular RNAs (nv-exRNAs) constitute the majority of the extracellular RNAome, but little is known about their stability, function, and potential use as disease biomarkers. Herein, we measured the stability of several naked RNAs when incubated in human serum, urine, and cerebrospinal fluid (CSF). We identified extracellularly produced tRNA-derived small RNAs (tDRs) with half-lives of several hours in CSF. Contrary to widespread assumptions, these intrinsically stable small RNAs are full-length tRNAs containing broken phosphodiester bonds (i.e., nicked tRNAs). Standard molecular biology protocols, including phenol-based RNA extraction and heat, induce the artifactual denaturation of nicked tRNAs and the consequent in vitro production of tDRs. Broken bonds are roadblocks for reverse transcriptases, preventing amplification and/or sequencing of nicked tRNAs in their native state. To solve this, we performed enzymatic repair of nicked tRNAs purified under native conditions, harnessing the intrinsic activity of phage and bacterial tRNA repair systems. Enzymatic repair regenerated an RNase R-resistant tRNA-sized band in northern blot and enabled RT-PCR amplification of full-length tRNAs. We also separated nicked tRNAs from tDRs by chromatographic methods under native conditions, identifying nicked tRNAs inside stressed cells and in vesicle-depleted human biofluids. Dissociation of nicked tRNAs produces single-stranded tDRs that can be spontaneously taken up by human epithelial cells, positioning stable nv-exRNAs as potentially relevant players in intercellular communication pathways.

Introduction Acute respiratory failure (ARF) is the main clinical sign of coronavirus disease-2019 (COVID-19), but little is known about the outcome of acute kidney injury (AKI) associated with ARF. Study design Retrospective cohort study on clinical features of adult patients hospitalized with COVID-19 between March 1st and April 30th, 2020 in the district of Piacenza (Italy). Results Among 1894 hospitalized patients, 1701 affected by COVID-19 underwent at least two serum creatinine evaluations. According to KDIGO definitions, 233 of 1,701 patients (13.7%) developed AKI: 159, 34, and 40 had stage 1, 2 and 3 AKI, respectively. Patients with AKI were older (mean age 73.5 ± 14 years, range 24–95) than those without AKI (72 ± 14 years, range 20–102). In-hospital mortality was high in COVID patients (567/1701 patients, 33%), which almost doubled among AKI patients (132/233 patients, 57%), compared with those without AKI ( p < 0.01). Risk factors for AKI included older age, male gender, diabetes and need for ventilation. Fourteen patients with stage 3 AKI underwent renal replacement therapy (RRT). Conclusions Hospitalized COVID-19 patients with AKI associated with ARF have poor chances of survival. Diagnosing and preventing the progression of renal damage is fundamental in order to delay initiating RRT, especially when resources are limited.

Normal values for 13 chemical constituents of plasma were estimated from results for 837 presumably healthy children. Ninety microliters of specimen was analyzed for lactate dehydrogenase, aspartate aminotransferase, alkaline phosphatase, inorganic phosphorus, total calcium, total cholesterol, total proteins, albumin, uric acid, urea nitrogen, alanine aminotransferase, total bilirubin, and glucose. We used two Abbott ABA-100 Bichromatic Analyzers interfaced directly to the ABA Data Management System. For each test age- and sex-related variations were assessed and normal values were estimated for six different age groups.

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