An NMR study of d(CTACTGCTTTAG).d(CTAAAGCAGTAG) showing hydration water molecules in the minor groove of a TpA step.

International audienceThe hydration properties of the non-palindromic duplex d(CTACTGCTTTAG). d(CTAAAGCAGTAG) were investigated by NMR spectroscopy. The oligonucleotide possesses a heterogeneous B-DNA structure. The H2(n)-H1'(m+1) distances reflect a minor groove narrowing within the TTT/AAA segment (approximately 3.9A) and a sudden widening at the T10:A15 base-pair (approximately 5.3A), the standard B-DNA distance being approximately 5A. The facing T10pA11 and T14pA15 steps at the end of the TTTA/AAAT segment have completely different behaviors. Only A15 ending the AAA run displays NMR features comparable to those shown by adenines of TpA steps occupying the central position of TnAn (n> or =2) segments. These involve particular chemical shifts and line broadening of the H2 and H8 protons. Positive NOESY cross-peaks were measured between the water protons and the H2 protons of A15, A16 and A17 reflecting the occurrence of hydration water molecules with residence times longer than 500 picoseconds along the minor groove of the TTT/AAA segment. In contrast no water molecules with long residence times were observed neither for A3, A20 and A23 nor for A11 ending the 5'TTTA run. We confirm thus that the binding of water molecules with long residence time to adenine residues correlates with the minor groove narrowing. In contrast, the widening of the minor groove at the A11:T14 base-pair ending the TTTA/TAAA segment, likely associated to a high negative propeller twist value at this base-pair, prevents the binding of a water molecule with long residence time to A11 but not to A15 of the preceding T10:A15 base-pair. Thus, in our non-palindromic oligonucleotide the water molecules bind differently to A11 and A15 although both adenines are part of a TpA step. The slower motions occurring at A15 compared to A11 are also well explained by the present results

Epidemiology and prognosis of anti-infective therapy in the ICU setting during acute pancreatitis: a cohort study

International audienceBACKGROUND: Recent international guidelines for acute pancreatitis (AP) recommend limiting anti-infective therapy (AIT) to cases of suspected necrotizing AP or nosocomial extrapancreatic infection. Limited data are available concerning empirical and documented AIT prescribing practices in patients admitted to the intensive care unit (ICU) for the management of AP.METHODS: Using a multicentre, retrospective (2009-2014), observational database of ICU patients admitted for AP, our primary objective was to assess the incidence of AIT prescribing practices during the first 30 days following admission. Secondary objectives were to assess the independent impact of centre characteristics on the incidence of AIT and to identify factors associated with crude hospital mortality in a logistic regression model.RESULTS: In this cohort of 860 patients, 359 (42%) received AIT on admission. Before day 30, 340/359 (95%) AIT patients and 226/501 (45%) AIT-free patients on admission received additional AIT, mainly for intra-abdominal and lung infections. A large heterogeneity was observed between centres in terms of the incidence of infections, therapeutic management including AIT and prognosis. Administration of AIT on admission or until day 30 was not associated with an increased mortality rate. Patients receiving AIT on admission had increased rates of complications (septic shock, intra-abdominal and pulmonary infections), therapeutic (surgical, percutaneous, endoscopic) interventions and increased length of ICU stay compared to AIT-free patients. Patients receiving delayed AIT after admission and until day 30 had increased rates of complications (respiratory distress syndrome, intra-abdominal and pulmonary infections), therapeutic interventions and increased length of ICU stay compared to those receiving AIT on admission. Risk factors for hospital mortality assessed on admission were age (adjusted odds ratio [95% confidence interval] 1.03 [1.02-1.05]; p < 0.0001), Balthazar score E (2.26 [1.43-3.56]; p < 0.0001), oliguria/anuria (2.18 [1.82-4.33]; p < 0.0001), vasoactive support (2.83 [1.73-4.62]; p < 0.0001) and mechanical ventilation (1.90 [1.15-3.14]; p = 0.011), but not AIT (0.63 [0.40-1.01]; p = 0.057).CONCLUSIONS: High proportions of ICU patients admitted for AP receive AIT, both on admission and during their ICU stay. A large heterogeneity was observed between centres in terms of incidence of infections, AIT prescribing practices, therapeutic management and outcome. AIT reflects the initial severity and complications of AP, but is not a risk factor for death

Self-association and domains of interactions of an amphipathic helix peptide inhibitor of HIV-1 integrase assessed by analytical ultracentrifugation and NMR experiments in trifluoroethanol/H(2)O mixtures.

International audienceEAA26 (VESMNEELKKIIAQVRAQAEHLKTAY) is a better inhibitor of human immunodeficiency virus, type 1, integrase than its parent Lys-159, reproducing the enzyme segment 147-175 with a nonpolar-polar/charged residue periodicity defined by four helical heptads (abcdefg) prone to collapse into a coiled-coil. Circular dichroism, nuclear magnetic resonance, sedimentation equilibrium, and chemical cross-linking were used to analyze EAA26 in various trifluoroethanol/H(2)O mixtures. In pure water the helix content is weak but increases regularly up to 50-60% trifluoroethanol. In contrast the multimerization follows a bell-shaped curve with monomers in pure water, tetramers at 10% trifluoroethanol, and dimers at 40% trifluoroethanol. All suggest that interhelical interactions between apolar side chains are required for the coiled-coil formation of EAA26 and subsist at medium trifluoroethanol concentration. The N(H) temperature coefficients measured by nuclear magnetic resonance show that at low trifluoroethanol concentration the amide groups buried in the hydrophobic interior of four alpha-helix bundles are weakly accessible to trifluoroethanol and are only weakly subject to its hydrogen bond strengthening effect. The increased accessibility of trifluoroethanol to buried amide groups at higher trifluoroethanol concentration entails the reduction of the hydrophobic interactions and the conversion of helix tetramers into helix dimers, the latter displaying a smaller hydrophobic interface. The better inhibitory activity of EAA26 compared with Lys-159 could arise from its better propensity to form a helix bundle structure with the biologically important helical part of the 147-175 segment in integrase

Du théâtre amateur. Approche historique et anthropologique.M.-M. Mervant-Roux (dir.)

Collection Arts du spectacle / Spectacles, histoire, sociét