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Galilean and Carrollian algebras acting on two-dimensional Newton-Cartan and Carrollian manifolds are isomorphic. A consequence of this property is a duality correspondence between one-dimensional Galilean and Carrollian fluids. We describe the dynamics of these systems as they emerge from the relevant limits of Lorentzian hydrodynamics, and explore the advertised duality relationship. This interchanges longitudinal and transverse directions with respect to the flow velocity, and permutes equilibrium and out-of-equilibrium observables, unveiling specific features of Carrollian physics. We investigate the action of local hydrodynamic-frame transformations in the Galilean and Carrollian configurations, i.e. dual Galilean and Carrollian local boosts, and comment on their potential breaking. Emphasis is laid on the additional geometric elements that are necessary to attain complete systems of hydrodynamic equations in Newton-Cartan and Carroll spacetimes. Our analysis is conducted in general Cartan frames as well as in more explicit coordinates, specifically suited to Galilean or Carrollian use. [ABSTRACT FROM AUTHOR]

Endothelin-1 (ET-1) is a potent vasoconstrictor produced by endothelial cells and cleared from circulating blood mainly in the pulmonary vasculature. In a healthy pulmonary circulation, the rate of local production of ET-1 is less than its rate of clearance. In the present study, we aimed to investigate whether the abnormal pulmonary circulatory handling of ET-1 relates to poor clinical outcomes in patients with coronavirus disease 2019 (COVID-19)-induced acute respiratory distress syndrome (ARDS). To this end, central venous and systemic arterial ET-1 plasma levels were simultaneously measured on Days 1 and 3 following ICU admission in mechanically ventilated COVID-19 patients with ARDS (COVID-19 ARDS, N = 18). Central venous and systemic arterial ET-1 plasma levels were also measured in two distinct SARS-CoV-2-negative mechanically ventilated critically ill patient groups, matched for age, sex, and critical illness severity, with ARDS (non-COVID-19 ARDS, N = 14) or without ARDS (non-COVID-19 non-ARDS, N = 20). Upon ICU admission, COVID-19-induced ARDS patients had higher systemic arterial and central venous ET-1 levels compared to the non-COVID-19 ARDS and non-COVID-19 non-ARDS patients (p < 0.05), yet a normal systemic arterial:central venous (A:V) ET-1 ratio [0.63 (0.49–1.02)], suggesting that pulmonary ET-1 clearance is intact in these patients. On the other hand, the non-COVID-19 ARDS patients demonstrated abnormal ET-1 handling [A:V ET-1 ratio 1.06 (0.93–1.20)], while the non-COVID-19 non-ARDS group showed normal ET-1 handling [0.79 (0.52–1.11)]. On Day 3, the A:V ratio in all three groups was <1. When the COVID-19 ARDS patients were divided based on 28-day ICU mortality, while their systemic arterial and central venous levels did not differ, the A:V ET-1 ratio was statistically significantly higher upon ICU admission in the non-survivors [0.95 (0.78–1.34)] compared to the survivors [0.57 (0.48–0.92), p = 0.027]. Our results highlight the potential importance of ET-1 as both a biomarker and a therapeutic target in critically ill COVID-19 patients. The elevated A:V ET-1 ratio in non-survivors suggests that the early disruption of pulmonary ET-1 handling may be a key marker of poor prognosis. [ABSTRACT FROM AUTHOR]

INTRODUCTION: The majority of fatal drug overdose cases are due to acute hypoxemic respiratory failure (AHRF). We examined whether AHRF associated with drug overdose has distinct features from AHRF associated with other risk factors. METHODS: We performed a secondary analysis of patient-level data from the LOTUS FRUIT study, a multicenter, prospective, observational study conducted by the PETAL Network. We classified patients with AHRF into the 'drugoverdose associated AHRF' (when PETAL investigators listed drug overdose as a risk factor of AHRF) versus the 'non-drug-overdose associated AHRF' group. To assess the association between drug overdose and 28-day mortality, we used a Cox proportional hazards regression analysis, both unadjusted and adjusted, and a mediation analysis. RESULTS: Of the 1280 patients with AHRF, 48 (3.8%) had drug-overdose associated AHRF. They were younger (42.0 vs 60.0 years), more likely to develop rapidly improving AHRF (50.0% vs 24.5%) and had lower unadjusted mortality than patients with non-drug-overdose associated AHRF (16.7% vs 34.4.%) (hazard ratio, HR=0.450; 95% CI: 0.223-0.905). However, after adjustment, drug overdose was no longer associated with lower mortality (adjusted hazard ratio, AHR=0.584; 95% CI: 0.288-1.185). Also, in mediation analysis, lower unadjusted mortality among patients with drug-overdose AHRF was significantly mediated by the development of rapidly improving AHRF (p<0.001 for the average causal mediation effect). CONCLUSIONS: Patients with drug-overdose associated AHRF were younger and had lower unadjusted mortality than patients with non-drug-overdose associated AHRF. However, this difference in mortality seemed to be due to confounders, such as age, and to be mediated by the development of rapidly improving AHRF. [ABSTRACT FROM AUTHOR]

The Hilbert matrix Hn,m=(n+m+1)−1$\mathcal {H}_{n,m} = (n+m+1)^{-1}$ has been extensively studied in the previous literature. In this paper, we look at generalized Hilbert operators arising from measures on the interval [0,1], such that the Hilbert matrix is obtained by the Lebesgue measure. We provide a necessary and sufficient condition for these operators to be bounded in ℓp$\ell ^p$ and calculate their norm. Interestingly, we obtain complete results in this direction for both p=1,∞$p=1, \infty$. [ABSTRACT FROM AUTHOR]

Severe COVID-19 is related to hyperinflammation and multiple organ injury, including respiratory failure, thus requiring intensive care unit (ICU) admission. Galectin-3, a carbohydrate-binding protein exhibiting pleiotropic effects, has been previously recognized to participate in inflammation, the immune response to infections and fibrosis. The aim of this study was to evaluate the relationship between galectin-3 and the clinical severity of COVID-19, as well as assess the prognostic accuracy of galectin-3 for the probability of ICU mortality. The study included 235 COVID-19 patients with active disease, treated in two different Greek hospitals in total. Our results showed that median galectin-3 serum levels on admission were significantly increased in critical COVID-19 patients (7.2 ng/mL), as compared to the median levels of patients with less severe disease (2.9 ng/mL, p = 0.003). Galectin-3 levels of the non-survivors hospitalized in the ICU were significantly higher than those of the survivors (median 9.1 ng/mL versus 5.8 ng/mL, p = 0.001). The prognostic accuracy of galectin-3 for the probability of ICU mortality was studied with a receiver operating characteristic (ROC) curve and a multivariate analysis further demonstrated that galectin-3 concentration at hospital admission could be assumed as an independent risk factor associated with ICU mortality. Our results were validated with galectin-3 measurements in a second patient cohort from a different Greek university hospital. Our results, apart from strongly confirming and advancing previous knowledge with two patient cohorts, explore the possibility of predicting ICU mortality, which could provide useful information to clinicians. Therefore, galectin-3 seems to establish its involvement in the prognosis of hospitalized COVID-19 patients, suggesting that it could serve as a promising biomarker in critical COVID-19. [ABSTRACT FROM AUTHOR]

Aging negatively affects the endothelium. Endocan (ESM-1), an endothelium-derived soluble proteoglycan, participates in fundamental biological processes of endothelial cells. We aimed to examine the role of endothelial dysfunction and age in poor outcomes in critical illness. ESM-1 levels were measured in the sera of mechanically ventilated critically ill patients, including COVID-19, non-septic, and septic patients. The 3 patient cohorts were divided based on age (≥65 and <65). Critically ill COVID-19 patients had statistically higher ESM-1 levels compared to critically ill septic and non-septic patients. Only in critically ill septic patients were ESM-1 levels higher in older compared to younger patients. Finally, the age-subgrouped patients were further subdivided based on intensive care unit (ICU) outcome. ESM-1 levels were similar in COVID-19 survivors and non-survivors, irrespective of age. Interestingly, only for the younger critically ill septic patients, non-survivors had higher ESM-1 levels compared to survivors. In the non-septic survivors and non-survivors, ESM-1 levels remained unaltered in the younger patients and tended to be higher in the elderly. Even though endocan has been recognized as an important prognostic biomarker in critically ill patients with sepsis, in our patient cohort, increased age, as well as the extent of endothelial dysfunction, seemed to affect its prognostic ability. [ABSTRACT FROM AUTHOR]

Summary: Growing evidence suggests that sleep could affect the immunological response after vaccination. The aim of this prospective study was to investigate possible associations between regular sleep disruption and immunity response after vaccination against coronavirus disease 2019 (COVID‐19). In total, 592 healthcare workers, with no previous history of COVID‐19, from eight major Greek hospitals were enrolled in this study. All subjects underwent two Pfizer–BioNTech messenger ribonucleic acid (mRNA) COVID‐19 vaccine BNT162b2 inoculations with an interval of 21 days between the doses. Furthermore, a questionnaire was completed 2 days after each vaccination and clinical characteristics, demographics, sleep duration, and habits were recorded. Blood samples were collected and anti‐spike immunoglobulin G antibodies were measured at 20 ± 1 days after the first dose and 21 ± 2 days after the second dose. A total of 544 subjects (30% males), with median (interquartile range [IQR]) age of 46 (38–54) years and body mass index of 24·84 (22.6–28.51) kg/m2 were eligible for the study. The median (IQR) habitual duration of sleep was 6 (6–7) h/night. In all, 283 participants (52%) had a short daytime nap. In 214 (39.3%) participants the Pittsburgh Sleep Quality Index score was >5, with a higher percentage in women (74·3%, p < 0.05). Antibody levels were associated with age (r = −0.178, p < 0.001), poor sleep quality (r = −0.094, p < 0.05), insomnia (r = −0.098, p < 0.05), and nap frequency per week (r = −0.098, p < 0.05), but after adjusting for confounders, only insomnia, gender, and age were independent determinants of antibody levels. It is important to emphasise that insomnia is associated with lower antibody levels against COVID‐19 after vaccination. [ABSTRACT FROM AUTHOR]