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Human endothelial cells cultured from umbilical vein (HUVEC) were tested for their ability to synthesize nitric oxide (NO), which has been identified as an endothelium-derived relaxing factor. The synthesis of this free radical (detected as citrulline, which is produced stoichiometrically with NO from arginine) in HUVEC is Ca2+ dependent, is increased sevenfold by the calcium ionophore ionomycin, and accounts for most basal and ionomycin-induced guanosine 3',5'-cyclic monophosphate (cGMP) production. Loading of cells with reduced glutathione (GSH), but not with N-(2-mercaptopropionyl)- glycine (MPG), led to increased citrulline production, both basally and after ionomycin stimulation. When the cells were depleted of GSH by incubation with 1-chloro-2,4-dinitrobenzene (CDNB), citrulline synthesis and cGMP production were inhibited in a concentration-dependent way. CDNB was not cytotoxic and did not inhibit cGMP increase elicited by sodium nitroprusside; cell loading with GSH (but not with MPG) relieved the block of citrulline synthesis. These results suggest that GSH is necessary in HUVEC for NO synthesis rather than for the NO effect on guanylate cyclase.

Objectives To explore the perspective of urological patients on the possibility to defer elective surgery due to the fear of contracting COVID-19. Methods All patients scheduled for elective urological procedures for malignant or benign diseases at two high-volume Centres were administered a questionnaire, through structured telephone interviews, between 24 th and 27 th April 2020. The questionnaire included three questions: 1) In light of the COVID-19 pandemic, would you defer the planned surgical intervention? 2) If yes, when would you be willing to undergo surgery? 3) What do you consider potentially more harmful for your health: the risk of contracting COVID-19 during hospitalization or the potential consequences of delaying surgical treatment? Results Overall, 332 patients were included (51.5% and 48.5% in the oncology and benign groups, respectively). Of these, 47.9% patients would have deferred the planned intervention (33.3% vs 63.4%; p<0.001), while the proportion of patients who would have preferred to delay surgery for more than six months was comparable between the groups (87% vs 80%). These answers were influenced by patient age and ASA score (in the Oncology group) and by the underlying urological condition (in the benign group). Finally, 182 (54.8%) patients considered the risk of COVID-19 potentially more harmful than the risk of delaying surgery (37% vs 73%; p<0.001). This answer was driven by patient age and the underlying disease in both groups. Conclusions Our findings reinforce the importance of shared decision-making before urological surgery, leveraging patients’ values and expectations to refine the paradigm of evidence-based medicine during the COVID-19 pandemic and beyond.

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