NMR investigations of the interaction between the azo-dye sunset yellow and Fluorophenol

The interaction of small molecules with larger noncovalent assemblies is important across a wide range of disciplines. Here, we apply two complementary NMR spectroscopic methods to investigate the interaction of various fluorophenol isomers with sunset yellow. This latter molecule is known to form noncovalent aggregates in isotropic solution, and form liquid crystals at high concentrations. We utilize the unique fluorine-19 nucleus of the fluorophenol as a reporter of the interactions via changes in both the observed chemical shift and diffusion coefficients. The data are interpreted in terms of the indefinite self-association model and simple modifications for the incorporation of a second species into an assembly. A change in association mode is tentatively assigned whereby the fluorophenol binds end-on with the sunset yellow aggregates at low concentration and inserts into the stacks at higher concentrations

Monitoring changes of paramagnetically-shifted 31P signals in phospholipid vesicles

Phospholipid vesicles are commonly used as biomimetics in the investigation of the interaction of various species with cell membranes. In this paper we present a 31P NMR investigation of a simple vesicle system using a paramagnetic shift reagent to probe the inner and outer layers of the lipid bilayer. Time-dependent changes in the 31P NMR signal are observed, which differ whether the paramagnetic species is inside or outside the vesicle, and on the choice of buffer solution used. An interpretation of these results is given in terms of the interaction of the paramagnetic shift reagent with the lipids

The Influence of Moderate Hypercapnia on Neural Activity in the Anesthetized Nonhuman Primate

Hypercapnia is often used as vasodilatory challenge in clinical applications and basic research. In functional magnetic resonance imaging (fMRI), elevated CO2 is applied to derive stimulus-induced changes in the cerebral rate of oxygen consumption (CMRO2) by measuring cerebral blood flow and blood-oxygenation-level–dependent (BOLD) signal. Such methods, however, assume that hypercapnia has no direct effect on CMRO2. In this study, we used combined intracortical recordings and fMRI in the visual cortex of anesthetized macaque monkeys to show that spontaneous neuronal activity is in fact significantly reduced by moderate hypercapnia. As expected, measurement of cerebral blood volume using an exogenous contrast agent and of BOLD signal showed that both are increased during hypercapnia. In contrast to this, spontaneous fluctuations of local field potentials in the beta and gamma frequency range as well as multiunit activity are reduced by ∼15% during inhalation of 6% CO2 (pCO2 = 56 mmHg). A strong tendency toward a reduction of neuronal activity was also found at CO2 inhalation of 3% (pCO2 = 45 mmHg). This suggests that CMRO2 might be reduced during hypercapnia and caution must be exercised when hypercapnia is applied to calibrate the BOLD signal

Advances, Challenges and Opportunities in 3D CMOS Sequential Integration

3D sequential integration enables the full use of the third dimension thanks to its high alignment performance. In this paper, we address the major challenges of 3D sequential integration: in particular, the control of molecular bonding allows us to obtain pristine quality top active layer. With the help of Solid Phase Epitaxy, we can match the performance of top FET, processed at low temperature (600°C), with the bottom FET devices. Finally, the development of a stable salicide enables to retain bottom performance after top FET processing. Overcoming these major technological issues offers a wide range of applications

Epidemiology of intra-abdominal infection and sepsis in critically ill patients: “AbSeS”, a multinational observational cohort study and ESICM Trials Group Project

Purpose: To describe the epidemiology of intra-abdominal infection in an international cohort of ICU patients according to a new system that classifies cases according to setting of infection acquisition (community-acquired, early onset hospital-acquired, and late-onset hospital-acquired), anatomical disruption (absent or present with localized or diffuse peritonitis), and severity of disease expression (infection, sepsis, and septic shock). Methods: We performed a multicenter (n = 309), observational, epidemiological study including adult ICU patients diagnosed with intra-abdominal infection. Risk factors for mortality were assessed by logistic regression analysis. Results: The cohort included 2621 patients. Setting of infection acquisition was community-acquired in 31.6%, early onset hospital-acquired in 25%, and late-onset hospital-acquired in 43.4% of patients. Overall prevalence of antimicrobial resistance was 26.3% and difficult-to-treat resistant Gram-negative bacteria 4.3%, with great variation according to geographic region. No difference in prevalence of antimicrobial resistance was observed according to setting of infection acquisition. Overall mortality was 29.1%. Independent risk factors for mortality included late-onset hospital-acquired infection, diffuse peritonitis, sepsis, septic shock, older age, malnutrition, liver failure, congestive heart failure, antimicrobial resistance (either methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, extended-spectrum beta-lactamase-producing Gram-negative bacteria, or carbapenem-resistant Gram-negative bacteria) and source control failure evidenced by either the need for surgical revision or persistent inflammation. Conclusion: This multinational, heterogeneous cohort of ICU patients with intra-abdominal infection revealed that setting of infection acquisition, anatomical disruption, and severity of disease expression are disease-specific phenotypic characteristics associated with outcome, irrespective of the type of infection. Antimicrobial resistance is equally common in community-acquired as in hospital-acquired infection

Study of the stereochemistry of silver(I) bis(pyridine-2-carbaldehyde-imine) triflate complexes in solution: application of INEPT109Ag and 1H-{109Ag}NMR

[Ag}I{L{2}](O{3}SCF{3}) complexes have been obtained from the 21 reaction of pyridine-2-carbaldehyde-imine (L) with AgO{3}SCF{3}. Inept }1{}0{}9{Ag and }1{H-{}1{}0{}9{Ag} NMR studies of [Ag{(S)(6-Me-2-C{5}H{3}N)C(H)=NC(H)PhMe}{2}](O{3}SCF{3}) reveal that the tetrahedral Ag}I{L{2} cation of this complex exists below 235 K in two diastereoisomeric forms with a strong preference for one of the molecular configurations (probably the A(S)(S))

Application of INEPT 109Ag and 15N NMR spectroscopy for the study of metal-ligand interaction of silver analogues of Copper(I) model compounds

Because of the presence of copper (in its reduced state) at active sites in protein it has become very important to study copper(I) model complexes by spectroscopic techniques.We now report that if copper(I) in model complexes can be substituted by silver(I) with retention of the structural features then }1{}0{}7{Ag or }1{}0{}9{Ag NMR spectroscopy (natural abundances 50% I = 12) using the recently developed polarization transfer sequence INEPT (Insensitive Nuclei Enhanced by Polarization Transfer) [1] provides an excellent tool for studying the metal IB-ligand interaction}1{H NMR studies show that the analogous copper(I) and silver(I) complexes of potentially quadridentate N{4} (R)(S)-1, 2-(6-R-pyridine-2-CH@?N){2}-cyclohexane (R = H or Me) as well as the N{2}S{2} donor ligand (R)(S)-1,2-(5-R-thiophene-2-CH@?N){2}-cyclohexane (R = H or Me) have similar structures (confirmed by X-ray studies [2]). However, study of the direct coordination sphere and copper(I)-ligand interactions in these model complexes by Cu NMR is hampered by the large quadropole moments of both }6{}3{Cu and }6{}5{Cu (natural abudances 70 and 30% respectively, I = 32).We have measured directly }1{}0{}9{Ag NMR (INEPT) spectra with large enhancements in signal to noise and enormous experimental time saving (a factor 400-500) as compared to the conventional methods (see Fig. 1) [3]. the influence of the nature of the hetero-atoms coordinating the metal centre is directly reflected in the chemical shift differences of the }1{}0{}9{Ag resonances.It is shown that for silver(I) coordination complexes information about the ligand-to-metal interaction can be obtained by using not only direct }1{}0{}9{Ag NMR, but also INEPT }1{}5{N NMR spectroscopy. In particular the }1{}5{N NMR (INEPT) spectra of the silver(I) complexes [M{2}(N{4}){2}]}2{}+{ 2O{3}SCF}-{{3} show that the structure of these complexes as found in the solid by X-ray methods, in which each metal ion has a distorted tetrahedral coordination geometry of four N-atoms, is fully retained in solution. From different }1{J(}1{}5{N@?}1{}0{}7{},{}1{}0{}9{Ag) coupling constants the relative bond strengths of the various Ag@?N interactions can be deduced.Where Cu}I{ can be substituted by Ag}I{ either in coordination (model) complexes or biological systems (bovine superoxide dismutase [4]) INEPT }1{}0{}9{Ag NMR spectroscopy has potential as a novel technique for the study of the coordinating properties of the metal centres