Nitric Oxide/Peroxynitrite Redox Imbalance in Endothelial Cells Measured with Amperometric Nanosensors

The cytoprotective messenger nitric oxide (NO) and cytotoxic peroxynitrite (ONOO-) are the main components of oxidative stress and can be generated by endothelial cells. A tandem of electrochemical nanosensors (diameter 200-300 nm) were used to measure, in situ, the balance between NO and ONOO-produced by human umbilical vein endothelial cells (HUVEC’s). The amperometric nanosensors were placed 5 ± 2 μm from the surface of the endothelial cells and the concentration of NO and ONOO- was measured at 630 mV and -300 mV (vs Ag/AgCl) respectively. Normal, functional, endothelial cells produced maximal 450 ± 25 nmol.L-1 of NO and 180 ± 15 nmol.L-1 of ONOO- in about 3 s, after stimulation with calcium ionophore. The in situ measurements of NO and ONOO- were validated using nitric oxide synthase inhibitor L-NMMA, ONOO- scavenger Mn(III) porphyrin, and superoxide dismutase (PEG-SOD). The ratio of NO concentration to ONOO- concentration ([NO]/[ONOO-]) was introduced for quantification of both, the redox balance and the level of the nitroxidative stress in the endothelium. [NO]/[ONOO-] was 2.7 ± 0.1 in a functional endothelium. The model of the dysfunctional endothelium was made by the treatment of HUVEC’s with angiotensin II for 20 min. Dysfunctional HUVEC’s produced only 115 ± 15 nmol.L-1 of NO, but generated a significantly higher concentration of ONOO- of 490 ± 30 nmol.L-1. The [NO]/[ONOO-] ratio decreased to 0.23 ± 0.14 in the dysfunctional endothelium. Electrochemical nanosensors can be effectively used for in situ monitoring of changing levels of nitroxidative/ oxidative stress, and may be useful in early medical diagnosis of the cardiovascular system.

The Role of Chest X-Ray in Monitoring Lung Changes among COVID-19 Patients in Gaza Strip

Objective: To investigate the time course and findings severity of COVID-19 infection at chest radiography based on a 6-point radiological severity score, and correlates these with patients’ age and gender. Methods: This is a retrospective study of COVID-19 patients who were admitted at European Gaza Hospital and evaluated between October 6, 2020, and November 30, 2020. Baseline and serial chest radiographs, up to 4 images per patient, were reviewed and assessed for predominant pattern, side, and location of lung opacity. Utilized a 6-point scoring system, which divides the chest X-ray into 6 zones, to assess chest X-ray changes and correlate them with the severity of infection, age, and gender of patients. Results: The study included 136 COVID-19 patients: (51/136, 37%) were males and (85/136, 62.5%) were females, while age ranged from 7 months to 90 years with a mean age of 41.7 ± (19.5) years. Negative Chest x-rays were more observed than positive images. Ground-glass opacity was the most frequent pattern with a decreasing trend from 1st to 4th chest X-ray (from 33.8% to 3.7%), followed by consolidation (from 16.2% to 2.9%). Also, the commonest pattern of opacity was seen in peripheral areas (27/136, 19.9%), lower zone location (23/136, 16.9%), and bilateral opacity involvement (43/136;31.6%). No significant correlation was noticed between the patient’s gender, age, and severity score (P > 0.05). Conclusions: The 6-point chest X-ray severity score as a predictive tool in assessing the severity due to provide an assessment of the progression or regression pathway.