Acid-base and metal ion binding properties of 2-thiocytidine in aqueous solution

The thionucleoside 2-thiocytidine (C2S) occurs in nature in transfer RNAs; it receives attention in diverse fields like drug research and nanotechnology. By potentiometric pH titrations we measured the acidity constants of H(C2S)(+) and the stability constants of the M(C2S)(2+) and M(C2S-H)(+) complexes (M2+ = Zn2+ , Cd2+), and we compared these results with those obtained previously for its parent nucleoside, cytidine (Cyd). Replacement of the (C2)=O unit by (C2)=S facilitates the release of the proton from (N3)H+ in H(C2S)(+) (pK (a) = 3.44) somewhat, compared with H(Cyd)(+) (pK (a) = 4.24). This moderate effect of about 0.8 pK units contrasts with the strong acidification of about 4 pK units of the (C4)NH2 group in C2S (pK (a) = 12.65) compared with Cyd (pK (a) approximate to 16.7); the reason for this result is that the amino-thione tautomer, which dominates for the neutral C2S molecule, is transformed upon deprotonation into the imino-thioate form with the negative charge largely located on the sulfur. In the M(C2S)(2+) complexes the (C2)S group is the primary binding site rather than N3 as is the case in the M(Cyd)(2+) complexes, though owing to chelate formation N3 is to some extent still involved in metal ion binding. Similarly, in the Zn(C2S-H)(+) and Cd(C2S-H)(+) complexes the main metal ion binding site is the (C2)S- unit (formation degree above 99.99 chelate formation with N3 must be surmised for the M(C2S-H)(+) species in accord with previous solid-state studies of related ligands. Upon metal ion binding, the deprotonation of the (C4)NH2 group (pK(a) = 12.65) is dramatically acidified (pK (a) approximate to 3), confirming the very high stability of the M(C2S-H)(+) complexes. To conclude, the hydrogen-bonding and metal ion complex forming capabilities of C2S differ strongly from those of its parent Cyd; this must have consequences for the properties of those RNAs which contain this thionucleoside

Differences in mortality in critically ill elderly patients during the second COVID-19 surge in Europe

Background!#!The primary aim of this study was to assess the outcome of elderly intensive care unit (ICU) patients treated during the spring and autumn COVID-19 surges in Europe.!##!Methods!#!This was a prospective European observational study (the COVIP study) in ICU patients aged 70 years and older admitted with COVID-19 disease from March to December 2020 to 159 ICUs in 14 European countries. An electronic database was used to register a number of parameters including: SOFA score, Clinical Frailty Scale, co-morbidities, usual ICU procedures and survival at 90 days. The study was registered at ClinicalTrials.gov (NCT04321265).!##!Results!#!In total, 2625 patients were included, 1327 from the first and 1298 from the second surge. Median age was 74 and 75 years in surge 1 and 2, respectively. SOFA score was higher in the first surge (median 6 versus 5, p < 0.0001). The PaO!##!Conclusion!#!An unexpected, but significant, decrease in 30-day and 90-day survival was observed during the second surge in our cohort of elderly ICU patients. The reason for this is unclear. Our main concern is whether the widespread changes in practice and treatment of COVID-19 between the two surges have contributed to this increased mortality in elderly patients. Further studies are urgently warranted to provide more evidence for current practice in elderly patients.!##!Trial registration number!#!NCT04321265 , registered March 19th, 2020

Health-related quality of life in older patients surviving ICU treatment for COVID-19: results from an international observational study of patients older than 70 years

International audienceBackground health-related quality of life (HRQoL) is an important patient-centred outcome in patients surviving ICU admission for COVID-19. It is currently not clear which domains of the HRQoL are most affected. Objective to quantify HRQoL in order to identify areas of interventions. Design prospective observation study. Setting admissions to European ICUs between March 2020 and February 2021. Subjects patients aged 70 years or older admitted with COVID-19 disease. Methods collected determinants include SOFA-score, Clinical Frailty Scale (CFS), number and timing of ICU procedures and limitation of care, Katz Activities of Daily Living (ADL) dependence score. HRQoL was assessed at 3 months after ICU admission with the Euro-QoL-5D-5L questionnaire. An outcome of ≥4 on any of Euro-QoL-5D-5L domains was considered unfavourable. Results in total 3,140 patients from 14 European countries were included in this study. Three months after inclusion, 1,224 patients (39.0%) were alive and the EQ-5D-5L from was obtained. The CFS was associated with an increased odds ratio for an unfavourable HRQoL outcome after 3 months; OR 1.15 (95% confidence interval (CI): 0.71–1.87) for CFS 2 to OR 4.33 (95% CI: 1.57–11.9) for CFS ≧ 7. The Katz ADL was not statistically significantly associated with HRQoL after 3 months. Conclusions in critically ill old intensive care patients suffering from COVID-19, the CFS is associated with the subjectively perceived quality of life. The CFS on admission can be used to inform patients and relatives on the risk of an unfavourable qualitative outcome if such patients survive