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Oxidative stress is an imbalance between oxidants (reactive oxygen and nitrogen species) and antioxidants that may affect lipids, DNA, carbohydrates and proteins. The lung is continuously exposed to endogenous and exogenous oxidants (cigarette smoke, mineral dust, ozone, radiation). Reactive oxygen and nitrogen species are mainly produced by phagocytes as well as by polymorphonuclear, alveolar, bronchial and endothelial cells. A potential role of oxidative stress in the pathogenesis of diffuse lung diseases (particularly idiopathic pulmonary fibrosis) has been demonstrated. Increased oxidant levels and decreased antioxidant defences can contribute to the progression of idiopathic pulmonary fibrosis and other diffuse lung diseases. The growing number of papers on the different aspects of oxidant/antioxidant imbalance in diffuse lung diseases in the last decade reflects increasing interest in this topic and suggests that specific DLDs may be characterized by specific patterns of oxidation and antioxidant responses. The study of oxidative stress can provide insights into etiopathogenesis and favour the discovery of new treatments. In this review of the literature on oxidants and antioxidants in diffuse lung diseases, the focus is on idiopathic pulmonary fibrosis, sarcoidosis, pneumoconiosis and pulmonary fibrosis associated with systemic sclerosis.

Chitotriosidase proved to be a biomarker with good sensitivity and specificity that is easily detected in serum. It can be proposed in clinical practice to identify progressive patients requiring close follow-up, to detect relapses and to evaluate the effects of therapy.

Severe acute respiratory syndrome coronavirus 2–induced direct cytopathic effects against type I and II pneumocytes mediate lung damage. Krebs von den Lungen‐6 (KL‐6) is mainly produced by damaged or regenerating alveolar type II pneumocytes. This preliminary study analyzed serum concentrations of KL‐6 in patients with coronavirus disease (COVID‐19) to verify its potential as a prognostic biomarker of severity. Twenty‐two patients (median age [interquartile range] 63 [59‐68] years, 16 males) with COVID‐19 were enrolled prospectively. Patients were divided into mild‐moderate and severe groups, according to respiratory impairment and clinical management. KL‐6 serum concentrations and lymphocyte subset were obtained. Peripheral natural killer (NK) cells/µL were significantly higher in nonsevere patients than in the severe group (P = .0449) and the best cut‐off value was 119 cells/µL. KL‐6 serum concentrations were significantly higher in severe patients than the nonsevere group (P = .0118). Receiver operating characteristic analysis distinguished severe and nonsevere patients according to KL‐6 serum levels and the best cut‐off value was 406.5 U/mL. NK cell analysis and assay of KL‐6 in serum can help identify severe COVID‐19 patients. Increased KL‐6 serum concentrations were observed in patients with severe pulmonary involvement, revealing a prognostic value and supporting the potential usefulness of KL‐6 measurement to evaluate COVID‐19 patients' prognosis.

Data availabilitySummary statistics generated by COVID-19 Host Genetics Initiative are available online (https://www.covid19hg.org/results/r6/). The analyses described here use the freeze 6 data. The COVID-19 Host Genetics Initiative continues to regularly release new data freezes. Summary statistics for samples from individuals of non-European ancestry are not currently available owing to the small individual sample sizes of these groups, but the results for 23 loci lead variants are reported in Supplementary Table 3. Individual-level data can be requested directly from the authors of the contributing studies, listed in Supplementary Table 1.

Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research. Patient consent for publication Not required. Provenance and peer review Not commissioned; internally peer reviewed. This article is made freely available for use in accordance with BMJ's website terms and conditions for the duration of the covid-19 pandemic or until otherwise determined by BMJ. You may use, download and print the article for any lawful, non-commercial purpose (including text and data mining) provided that all copyright notices and trade marks are retained.

A new proton anisotropic-isotropic shift correlation experiment is described which operates with ultrafast MAS, resulting in good resolution of isotropic proton shifts in the detection dimension. The new experiment makes use of a recoupling sequence designed using symmetry principles which reintroduces the proton chemical shift anisotropy in the indirect dimension. The experiment has been used to measure the proton shift tensor parameters for the OH hydrogen-bonded protons in tyrosine.HCl and citric acid at Larmor frequencies of up to 850 MHz.

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