Études RMN en série hétérocyclique

Deux méthodes ont été utilisées pour essayer de déterminer la constante d’équilibre tautomère des pyrazoles non substitués à l’azote, à partir des déplacements chimiques 14N

A ^(15)N NMR Study of the Ring-Opening of Methylsydnonimine Hydrochloride

Nitrogen-15 NMR spectroscopy has been used to study the irreversible ring-cleavage or 3-methylsydnonimine hydrochloride samples separately labeled with ^(15)N at each or the three possible nitrogens. This reaction, which occurs in hydroxylic solvents on addition of base, initially yields principally the E and Z isomers or N-methyl-N-cyanomethylnitrosamine. While 3-methylsydnonimine itselr is surely a transient intermediate in the ring-opening, no measurable concentration of the free base could be detected by ^(15)N NMR. Hydrolysis or the cyano group of N-methyl-N-cyanomethylnitrosamine to give E and Z isomers of N-methyl-N-nitrosoglycine amide and N-methyl-N-nitrosoglycine could also be followed by ^(15)N NMR and is reasonably facile in that it occurs significantly at below room temperature

Metabolic syndrome is associated with similar long-term prognosis in non-obese and obese patients. An analysis of 45 615 patients from the nationwide LIPIDOGRAM 2004-2015 cohort studies

Aims We aimed to evaluate the association between metabolic syndrome (MetS) and long-term all-cause mortality. Methods The LIPIDOGRAM studies were carried out in the primary care in Poland in 2004, 2006 and 2015. MetS was diagnosed based on the National Cholesterol Education Program, Adult Treatment Panel III (NCEP/ATP III) and Joint Interim Statement (JIS) criteria. The cohort was divided into four groups: non-obese patients without MetS, obese patients without MetS, non-obese patients with MetS and obese patients with MetS. Differences in all-cause mortality was analyzed using Kaplan-Meier and Cox regression analyses. Results 45,615 participants were enrolled (mean age 56.3, standard deviation: 11.8 years; 61.7% female). MetS was diagnosed in 14,202 (31%) by NCEP/ATP III criteria, and 17,216 (37.7%) by JIS criteria. Follow-up was available for 44,620 (97.8%, median duration 15.3 years) patients. MetS was associated with increased mortality risk among the obese (hazard ratio, HR: 1.88 [95% CI, 1.79-1.99] and HR: 1.93 [95% CI 1.82-2.04], according to NCEP/ATP III and JIS criteria, respectively) and non-obese individuals (HR: 2.11 [95% CI 1.85-2.40] and 1.7 [95% CI, 1.56-1.85] according to NCEP/ATP III and JIS criteria respectively). Obese patients without MetS had a higher mortality risk than non-obese patients without MetS (HR: 1.16 [95% CI 1.10-1.23] and HR: 1.22 [95%CI 1.15-1.30], respectively in subgroups with NCEP/ATP III and JIS criteria applied). Conclusions MetS is associated with increased all-cause mortality risk in non-obese and obese patients. In patients without MetS obesity remains significantly associated with mortality. The concept of metabolically healthy obesity should be revised