Sildenafil Prevents Endothelial Dysfunction Induced by Ischemia and Reperfusion via Opening of Adenosine Triphosphate–Sensitive Potassium Channels

Background— Animal studies have demonstrated that administration of sildenafil can limit myocardial damage induced by prolonged ischemia, an effect that appears to be mediated by opening of adenosine triphosphate–sensitive potassium (K ATP ) channels. No study has investigated whether sildenafil can also prevent the impairment in endothelium-dependent vasodilatation induced by ischemia-reperfusion (IR) in humans. Methods and Results— In a double-blind, placebo-controlled, crossover design, 10 healthy male volunteers (25 to 45 years old) were randomized to oral sildenafil (50 mg) or placebo. Two hours later, endothelium-dependent, flow-mediated dilatation (FMD) of the radial artery was measured before and after IR (15 minutes of ischemia at the level of the brachial artery followed by 15 minutes of reperfusion). Seven days later, subjects received the other treatment (ie, placebo or sildenafil) and underwent the same protocol. Pre-IR radial artery diameter and FMD, as well as baseline radial artery diameter after IR, were similar between visits ( P =NS). After placebo administration, IR significantly blunted FMD (before IR: 7.9±1.1%; after IR: 1.2±0.7%, P <0.01). Importantly, sildenafil limited this impairment in endothelium-dependent vasodilatation (before IR: 7.0±0.9%; after IR: 6.2±1.1%, P =NS; P <0.01 compared with placebo). In a separate protocol, this protective effect was completely prevented by previous administration of the sulfonylurea glibenclamide (glyburide, 5 mg), a blocker of K ATP channels (n=7; FMD before IR: 10.3±1.5%; after IR: 1.3±1.4%, P <0.05). Conclusions— In humans, oral sildenafil induces potent protection against IR-induced endothelial dysfunction through opening of K ATP channels. Further studies are needed to test the potential clinical implications of this finding

Microservices: Yesterday, Today, and Tomorrow

The microservice architecture is a style inspired by service-oriented computing that has recently started gaining popularity. Before presenting the current state-of-the-art in the field, this chapter reviews the history of software architecture, the reasons that led to the diffusion of objects and services first, and microservices later. Finally, open problems and future challenges are introduced. This survey addresses mostly newcomers to the discipline and offers an academic viewpoint on the topic. In addition, practical aspects are investigated and solutions proposed

Comparable Post-Vaccination Decay of Neutralizing Antibody Response to Wild-Type and Delta SARS-CoV-2 Variant in Healthcare Workers Recovered from Mild or Asymptomatic Infection

: We described the long-term decay of neutralizing antibody (NtAb) to the wild-type and Delta SARS-CoV-2 variant after three antigen stimulations (mild or asymptomatic natural infection followed by two doses of the BNT162b2 mRNA vaccine after a median of 296 days) in immunocompetent healthcare workers (HCWs). Live virus microneutralization against the B.1 and Delta SARS-CoV-2 variants was performed in VERO E6 cell cultures. The median NtAb titers for B.1 and Delta were comparable and highly correlated at both 20 and 200 days after the second vaccine dose in the 23 HCWs enrolled (median age, 46 years). A small group of naturally infected unvaccinated HCWs had comparable NtAb titers for the two strains after a median follow-up of 522 days from infection diagnosis. The NtAb response to the Delta VoC appears to follow the same long-term dynamics as the wild-type response regardless of the vaccinal boost; data collected after three antigen stimulations (natural infection followed by two doses of the BNT162b2 mRNA vaccine) may be helpful for tailoring the continuous monitoring of vaccine protection against SARS-CoV-2 variants over time

Single-dose BNT162b2 mRNA COVID-19 vaccine significantly boosts neutralizing antibody response in health care workers recovering from asymptomatic or mild natural SARS-CoV-2 infection

Objectives: To measure SARS-CoV-2 neutralizing antibody (NtAb) titres in previously infected or uninfected health care workers who received one or two doses of BNT162b2 mRNA COVID-19 vaccine. Methods: NtAbs were titrated as dose-inhibiting 50% virus replication (ID50) by live virus microneutralization. We evaluated 41 health care workers recovering from mild or asymptomatic infection at first vaccination dose (T1_inf) and 21 days later (T2_inf). Sixteen uninfected health care workers were evaluated 20 days after first dose (T2_uninf) and 20 days after second vaccine dose (T3_uninf). Results: At T2_inf, but not at T1_inf, there was a significant correlation between days from diagnosis (median 313, interquartile range 285–322) and NtAb levels (P = 0.011). NtAb titres increased at T2_inf with respect to T1_inf (1544 (732–2232) vs 26 (10–88), P < 0.001). Similarly, there was a significant increase in NtAb titres at T3_uninf compared with T2_uninf (183 (111–301) vs 5 (5–15), P < 0001). However, NtAb levels at T2_inf were significantly higher than those at T2_uninf and T3_uninf (P < 0.0001 for both analyses). Conclusions: A single vaccination in people with mild or asymptomatic previous infection further boosts SARS-CoV-2 humoral immunity to levels higher than those obtained by complete two-vaccination in uninfected subjects

BNT162b2 SARS-CoV-2 Vaccination Elicits High Titers of Neutralizing Antibodies to Both B.1 and P.1 Variants in Previously Infected and Uninfected Subjects

: We aimed to investigate neutralizing antibody titers (NtAbT) to the P.1 and B.1 SARS-CoV-2 variants in a cohort of healthy health care workers (HCW), including 20 previously infected individuals tested at baseline (BLinf, after a median of 298 days from diagnosis) and 21 days after receiving one vaccine dose (D1inf) and 15 uninfected subjects tested 21 days after the second-dose vaccination (D2uninf). All the subjects received BNT162b2 vaccination. D1inf NtAbT increased significantly with respect to BLinf against both B.1 and P.1 variants, with a fold-change significantly higher for P.1. D1inf NtAbT were significantly higher than D2uninf NtAbT, against B.1 and P.1. NtAbT against the two strains were highly correlated. P.1 NtAbT were significantly higher than B.1 NtAbT. This difference was significant for post-vaccination sera in infected and uninfected subjects. A single-dose BNT162b2 vaccination substantially boosted the NtAb response to both variants in the previously infected subjects. NtAb titers to B.1 and P.1 lineages were highly correlated, suggesting substantial cross-neutralization. Higher titers to the P.1 than to the B.1 strain were driven by the post-vaccination titers, highlighting that cross-neutralization can be enhanced by vaccination

Faster decay of neutralizing antibodies in never infected than previously infected healthcare workers three months after the second BNT162b2 mRNA COVID-19 vaccine dose

Objectives: Our aim was to describe the longitudinal evolution of neutralizing antibody titres (NtAb) in three different cohorts of healthcare workers including vaccinated individuals with and without a previous SARS-CoV-2 infection and previously infected unvaccinated subjects. COVID-19 was mild or asymptomatic in those experiencing infection. Methods: NtAb was tested before BNT162b2 mRNA COVID-19 vaccine (V0), 20±2 days after the first dose (V1_20), 20±3 days (V2_20) and 90±2 days (V2_90) after the second dose in vaccinated HCW and after about 2 months (N_60), 10 months (N_300) and 13 months (N_390) from natural infection in unvaccinated HCW. NtAb was measured by authentic virus neutralization with a SARS-CoV-2 B.1 isolate circulating in Italy at HCW enrolment. Results: Sixty-two HCW were enrolled. NtAb were comparable in infected HCW with no or mild disease at all the study points. NtAb of uninfected HCW were significantly lower with respect to those of previously infected subjects at V1_20, V2_20 and V2_90. The median NtAb fold decrease from V2_20 to V2_90 was higher in the uninfected subjects with respect to subjects with mild infection (6.26 vs 2.58, p=0.03) and to asymptomatic HCW (6.26 vs 3.67, p=0.022). The median Nabt at N_390 was significantly lower with respect to N_60, p=0.007). Conclusions: In uninfected subjects completing the two-dose vaccine schedule, a third mRNA vaccine dose is a reasonable option to counteract the substantial NtAb decline occurring at a significantly higher rate compared to previously infected, vaccinated subjects. Although at low level Nabt are still at detectable level after 13 months in two third of previously infected and not vaccinated subjects