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We obtained chest computed tomography (CT) sections in 12 normal subjects (controls) and 17 patients with the adult respiratory distress syndrome (ARDS) to investigate regional lung inflation. A basal CT section (just above the diaphragm) was obtained in the supine position at zero cm H2O end-expiratory pressure. In each CT section the distance from ventral to dorsal surface (hT) was divided into 10 equal intervals, and 10 lung levels from ventral (no. 1) to dorsal (no. 10) were defined. Knowing the average density and the volume of each level, we computed: (1) the tissue volume; (2) the gas/tissue (g/t) ratio (index of regional inflation); (3) the hydrostatic pressure superimposed on each level (SPL), estimated as density x height. The total volume of the basal CT section was 49 +/- 2.5 ml x m-2 (mean +/- SE) in control subjects and 43 +/- 2.3 ml x m-2 in patients with ARDS (p = not significant [NS]). The tissue volume, however, was 16.7 +/- 0.8 ml x m-2 in control subjects and 31.6 +/- 1.7 ml x m-2 in patients with ARDS (p < 0.01). The g/t ratio in level 1 averaged 4.7 +/- 0.5 in control subjects and 1.2 +/- 0.2 in patients with ARDS (p < 0.01), and this ratio decreased exponentially from level 1 to level 10, both in controls and patients with ARDS. The Kd constant of the exponential decrease was 13.9 +/- 1.3 cm in control subjects and 7.8 +/- 0.8 cm in patients with ARDS (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Free radicals have acquired growing importance in the fields of biology and medicine. They are produced during many different endogenous and exogenous processes. Mitochondria are the main source of endogenous reactive oxygen species (ROS) produced at cell level. The overproduction of free radicals can damage macromolecules such as nucleic acids, proteins and lipids. This leads to tissue damage in various chronic and degenerative diseases. Antioxidants play a crucial role in the body’s defense against free radicals. This review concerns the main properties of free radicals, their sources and deleterious effects. It highlights the potential role of the dietary supplementation of antioxidants and discusses unsolved problems regarding antioxidant supplements in the prevention and therapy of diseases.

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Purpose : To investigate retinal vessel density changes in macular and papillary regions in post SARS-CoV-2 pneumonia patients by means of optical coherence tomography angiography (OCTA). Design : Prospective, observational, cohort study. Methods : Forty eyes of 40 patients (mean age 49.7 ± 12.6) post SARS-CoV-2 infection and 40 healthy subjects were enrolled in this study. Covid-19 patients had to be fully recovered from Covid-19 pneumonia and were evaluated 6 months after Covid-19 infection. The primary outcome was the results of the OCTA study of the following vascular structures: vessel density (VD) in the retinal superficial capillary plexus (SCP), deep capillary plexus (DCP), radial peripapillary capillaries (RPC), compared to those of controls. We also evaluated the structural spectral domain (SD)-OCT parameters: ganglion cell complex (GCC) and retinal nerve fiber layer (RNFL). Results : The patients showed a significant reduction in VD of the SCP in whole image and in the DCP in all sectors compared to healthy subjects (p<0.05). Covid-19 patients featured a reduced VD of the RPC compared to controls (p<0.001). No difference was found in the GCC, while the RNFL was reduced in the COVID-19 group compared to controls (p=0.012). Significant correlations were found between the RNFL and VD of the SCP, DCP, RPC and FAZ area in the Covid-19 group (p<0.05). Conclusion : OCTA showed retinal vascular changes in subjects fully recovered from Covid-19 pneumonia. These findings could be a consequence of a thrombotic microangiopathy that affected retinal structures as well as other systemic organs. OCTA could represent a valid, non-invasive biomarker of early vascular dysfunction after SARS-CoV-2 infection.