The Phantom Urine: An Unexpected Finding during a Routine Cesarean Section.

We present here an atypical finding during an elective repeat cesarean section. Despite urine flow through an indwelling bladder catheter, bladder remains distended during the whole procedure. Unexpected anatomical variations and malformations can make routine surgery challenging. Urinary tract anomalies should be suspected in cases of unexpected difficult bladder catheterization

Collisional excitation rate coefficients of N2H+ by He

Using a recoupling technique with close-coupling spin-free calculations de-excitation rate coefficients are obtained among hyperfine transitions for He colliding with N2H+. A recently determined potential energy surface suitable for scattering calculations is used to investigate rate coefficients for temperatures between 5 and 50 K, and for the seven lowest rotational levels of N2H+. Fitting functions are provided for the Maxwellian averaged opacity tensors and for the rotational de-excitation collisional rate coefficients. The fitting functions for the opacity tensors can be used to calculate hyperfine (de)-excitation rate coefficients among elastic and inelastic rotational levels, and among the corresponding magnetic sublevels of the hyperfine structure. Certain dynamical approximations are investigated and found to be invali

MHC-correlated preferences in diestrous female horses (Equus caballus).

Genes of the major histocompatibility complex (MHC) have been shown to influence communication in many vertebrates, possibly with context-specific MHC-correlated reactions. Here we test for MHC-linked female preferences in the polygynous horse (Equus caballus) by repeatedly exposing 19 mares to a group of seven sexually experienced stallions. Each mare was tested four times during two consecutive reproductive cycles, twice during estrus and twice during diestrus. Male plasma testosterone concentrations were determined from weekly blood samples, and equine leukocyte antigen (ELA) class I and II alleles were determined serologically at the end of the experiments. Perception of male attractiveness was strongly dependent on estrous cycle: mean preference scores did not correlate for mares in diestrus and estrus and varied more during estrus than during diestrus. We found elevated female interests for MHC-dissimilar stallions, but only during diestrus, not during estrus. Female preferences were not significantly predicted by mean male testosterone plasma concentrations. However, testosterone concentrations changed during the 11 weeks of the experiment. By the end of the experiment, average testosterone concentration was significantly correlated to the average number of MHC alleles the stallions shared with the mares. We conclude that the MHC affects female preferences for stallions, but non-MHC linked male characteristics can overshadow effects of the MHC during estrus

Allosteric control of cyclic di-GMP signaling

Cyclic di-guanosine monophosphate is a bacterial second messenger that has been implicated in biofilm formation, antibiotic resistance, and persistence of pathogenic bacteria in their animal host. Although the enzymes responsible for the regulation of cellular levels of c-di-GMP, diguanylate cyclases (DGC) and phosphodiesterases, have been identified recently, little information is available on the molecular mechanisms involved in controlling the activity of these key enzymes or on the specific interactions of c-di-GMP with effector proteins. By using a combination of genetic, biochemical, and modeling techniques we demonstrate that an allosteric binding site for c-di-GMP (I-site) is responsible for non-competitive product inhibition of DGCs. The I-site was mapped in both multi- and single domain DGC proteins and is fully contained within the GGDEF domain itself. In vivo selection experiments and kinetic analysis of the evolved I-site mutants led to the definition of an RXXD motif as the core c-di-GMP binding site. Based on these results and based on the observation that the I-site is conserved in a majority of known and potential DGC proteins, we propose that product inhibition of DGCs is of fundamental importance for c-di-GMP signaling and cellular homeostasis. The definition of the I-site binding pocket provides an entry point into unraveling the molecular mechanisms of ligand-protein interactions involved in c-di-GMP signaling and makes DGCs a valuable target for drug design to develop new strategies against biofilm-related diseases

A high-resolution infrared spectroscopic investigation of the halogen atom-HCN entrance channel complexes solvated in superfluid helium droplets

Rotationally resolved infrared spectra are reported for the X-HCN (X = Cl, Br, I) binary complexes solvated in helium nanodroplets. These results are directly compared with that obtained previously for the corresponding X-HF complexes [J. M. Merritt, J. K\"upper, and R. E. Miller, PCCP, 7, 67 (2005)]. For bromine and iodine atoms complexed with HCN, two linear structures are observed and assigned to the $^{2}\Sigma_{1/2}$ and $^{2}\Pi_{3/2}$ ground electronic states of the nitrogen and hydrogen bound geometries, respectively. Experiments for HCN + chlorine atoms give rise to only a single band which is attributed to the nitrogen bound isomer. That the hydrogen bound isomer is not stabilized is rationalized in terms of a lowering of the isomerization barrier by spin-orbit coupling. Theoretical calculations with and without spin-orbit coupling have also been performed and are compared with our experimental results. The possibility of stabilizing high-energy structures containing multiple radicals is discussed, motivated by preliminary spectroscopic evidence for the di-radical Br-HCCCN-Br complex. Spectra for the corresponding molecular halogen HCN-X$_{2}$ complexes are also presented.Comment: 20 pages, 15 figures, 6 tables, RevTe

Reproducing kernel potential energy surfaces in biomolecular simulations: Nitric oxide binding to myoglobin

Multidimensional potential energy surfaces based on reproducing kernel-interpolation are employed to explore the energetics and dynamics of free and bound nitric oxide in myoglobin (Mb). Combining a force field description for the majority of degrees of freedom and the higher-accuracy representation for the NO ligand and the Fe out-of-plane motion allows for a simulation approach akin to a mixed quantum mechanics/molecular mechanics treatment. However, the kernel-representation can be evaluated at conventional force-field speed. With the explicit inclusion of the Fe-out-of-plane (Fe-oop) coordinate, the dynamics and structural equilibrium after photodissociation of the ligand are correctly described compared to experiment. Experimentally, the Fe-oop coordinate plays an important role for the ligand dynamics. This is also found here where the isomerization dynamics between the Fe-ON and Fe-NO state is significantly affected whether or not this co-ordinate is explicitly included. Although the Fe-ON conformation is metastable when considering only the bound (2)A state, it may disappear once the (4)A state is included. This explains the absence of the Fe-ON state in previous experimental investigations of MbNO

Entrance Channel X-HF (X=Cl, Br, and I) Complexes studied by High-Resolution Infrared Laser Spectroscopy in Helium Nanodroplets

Rotationally resolved infrared spectra are reported for halogen atom - HF free radical complexes formed in helium nanodroplets. An effusive pyrolysis source is used to dope helium droplets with Cl, Br and I atoms, formed by thermal dissociation of Cl$_2$, Br$_2$ and I$_2$. A single hydrogen fluoride molecule is then added to the droplets, resulting in the formation of the X-HF complexes of interest. Analysis of the resulting spectra confirms that the observed species have $^2\Pi_{3/2}$ ground electronic states, consistent with the linear hydrogen bound structures predicted from theory. Stark spectra are also reported for these species, from which the permanent electric dipole moments are determined.Comment: 41 pages, 16 figures, 5 table

Potential energy surfaces and bound states for the open-shell van der Waals cluster Br–HF

Semiempiricalpotential energy surfaces for the lowest three electronic states of the open-shell complex Br–HF are constructed, based on existing empirical potentials for Kr–HF and Kr–Ne and coupled-clusterelectronic structure calculations for Br–Ne. Coupled cluster calculations are also described for He–F, Ne–F and Ar–F. Electrostaticinteractions that arise from the quadrupole of the Br atom and the permanent multipoles of HF are also included in the Br–HF surfaces. The well depth of the lowest adiabatic surface is found to be 670 cm−1 at a linear equilibrium geometry. The results of helicity decoupled and full close-coupling calculations of the bound states of the complex are also described. The ground state, with total angular momentum projection quantum number |P|=3/2, is found 435 cm−1 below dissociation to Br (2P3/2)+HF (j=0). The lowest-frequency intermolecular bending and stretching vibrations are predicted around 145 and 211 cm−1, respectively. Parity splittings are found to be extremely small for bound states with projection quantum number |P|=3/2. The relevance of the results to recently recorded spectra of Br–HF is discussed

Impact de l'introduction des panels gastro-intestinaux par PCR multiplex sur le traitement des infections digestives

Cette étude vise à évaluer l’intérêt des nouvelles PCR (Polymerase Chain Reaction) multiplex du laboratoire microbiologique du CHUV (Centre Hospitalier Universitaire Vaudois) dans la prise en charge clinique des gastroentérites. Les PCR sont actuellement implantée dans beaucoup de laboratoire. Leur supériorité technique sur les méthodes de détections traditionnelles a été largement étudiée. Cependant peu d’études se sont intéressées à l’influences des PCR sur la prise en charge cliniques des patients. Nous avons voulu dans cette étude, analyser les différences de prises en charge clinique en fonction de l’outil diagnostique. Deux groupes de patients consultant en ambulatoires pour des symptomes de gastroentérite les urgences du CHUV ou de la PMU (Policlinique Médicale Universitaire) ont été comparés sur une période de deux ans. Le premier groupe a été investigué par les méthodes de laboratoire microbiologique traditionnelles (culture, test Elisa, microscopie, test d’antigène ou de toxine) et le second par PCR multiplex (panels de bactéries entéropathogènes, protozoaires digestif, C.difficile ou Norovirus). Ces deux cohortes ont été comparées selon les résultats d’examens et les décisions cliniques des médecins, notamment en termes de traitement anti-infectieux. Dans la cohorte de patients étant investigués par panels PCR, nous avons relevés trois changements significatifs. 1. Une baisse de 44% du nombre de patients traités par traitements anti-infectieux prescrits dans leur entier ; 2. Une augmentation de 80% du nombre de bactéries détectées ; 3. Une baisse de 64% du nombre de patients ayant reçu un résultat négatif qui avaient été traités par traitement anti-infectieux empirique. Malgré une augmentation de détection des bactéries, il est observé une baisse des prescriptions d’antiinfectieux. Ce qui peut être expliqué d’une part par le fait que les cliniciens, sachant qu’ils vont obtenir rapidement un résultat, peuvent se permettre de ne pas traiter empiriquement certains patients et de les réévaluer lorsqu’ils auront obtenu le résultat d’examen de selle. D’autre part, le fait d’obtenir un résultat précoce permet d’arrêter les thérapies inutiles que ce soit chez les patients avec un résultat négatifs ou ceux positifs pour des pathogènes qui ne nécessitent pas forcément de traitement. Globalement, les médecins prescrivent moins de traitements empiriques lorsqu’ils savent que les résultats de laboratoire seront rapidement disponibles et que la suspicion d’enteropathogènes bactériens est faible. Grâce au court délai des panels PCR, les traitements anti-infectieux prescrits sont ainsi plus adéquats, évités ou interrompus précocement lorsqu’ils sont inutiles ou mieux ciblés lorsqu’ils sont nécessaires L’introduction des panels PCR, a donc permis d’améliorer la prise en charge ambulatoire des gastroentérites, tout en diminuant la prescription d’antibiotiques