Water Exclusion at the Nanometer Scale Provides Long-Term Passivation of Silicon (111) Grafted with Alkyl Monolayers

This work is a quantitative study of the conditions required for a long-term passivation of the interface silicon-alkyl monolayers prepared by thermal hydrosilyation of neat 1-alkenes on well-defined H-Si(111) surfaces. We present electrochemical capacitance measurements (C-U) in combination with ex situ atomic force microscopy (AFM) observations and X-ray photoelectron spectroscopy (XPS) measurements. Capacitance measurements as a function of the reaction time and XPS data reveal close correlations between the chemical composition at the interface and its electronic properties. A very low density of states is found if suboxide formation is carefully prevented. The monitoring of C-U plots and AFM imaging upon exposure of the sample in diverse conditions indicate that the initial electronic properties and structure of the interface are long-lasting only when the monolayer surface coverage is theta > 0.42. A model demonstrates that this threshold value corresponds to a monolayer with intermolecular channels narrower than approximately 2.82 A, which is equal to the diameter of a water molecule. Water exclusion from the monolayer promotes long-term passivation of the silicon surface against oxidation in air and water as well as perfect corrosion inhibition in 20% NH(4)F. We provide two criteria to assess when a sample is optimized: The first one is an effective dielectric constant <2.5, and the second one is a very characteristic energy diagram at open circuit potential.

Design, synthesis, and structure-activity relationships of 1-,3-,8-, and 9-substituted-9-deazaxanthines at the human A2B adenosine receptor

Over two hundred 1-, 3-, 8-, and 9-substituted-9-deazaxanthines were prepared and evaluated for their binding affinity at the recombinant human adenosine receptors, in particular at the hA(2B) and hA(2A) subtypes. Several ligands endowed with sub-micromolar to low nanomolar binding affinity at hA(2B) receptors, good selectivity over hA(2A) and hA(3), but a relatively poor selectivity over hA(1) were obtained. Good antagonistic potencies and efficacies, with pA(2) values close to the corresponding pK(i)s, were observed in functional assays in vitro performed on a selected series of compounds. 1,3-Dimethyl-8-phenoxy-(N-p-halogenophenyl)-acetamido-9-deazaxanthine derivatives appeared as the most interesting leads, some of them showing outstanding hA(2B) affinities, high selectivity over hA(2A) and hA(3), but low selectivity over hA(1). Structure-affinity relationships suggested that the binding potency at the hA(2B) receptor was mainly modulated by the steric (lipophilic) properties of the substituents at positions 1 and 3 and by the electronic and lipophilic characteristics of the substituents at position 8. A comparison among affinity and selectivity profiles of 9-deazaxanthines with the corresponding xanthines suggested some possible differences in their binding mode.

Inspired oxygen fraction achieved with a portable ventilator: determinant factors

INTRODUCTION

Non-invasive positive pressure ventilation (NIPPV) is an effective treatment in respiratory failure. Continuous positive pressure (CPAP) may also be useful in acute hypoxaemic patients. Supplementary oxygen is usually necessary in both systems. However, the inspired oxygen fraction (FiO2) delivered by a NIV portable ventilator is unknown. The main objectives of this study were to establish the maximal FiO2 that could be achieved by these devices and to analyse the FiO2 determinant factors.

METHOD

Ten healthy volunteers were evaluated using a BiPAP ST30 ventilator (Respironics, USA) with a single-limb circuit, expiratory port and nasal mask (Respironics, USA). Oxygen (15 L/min) was administered at two connection points (proximal and distal). Each volunteer carried out a NIPPV (inspiratory pressure 20 cmH2O [1.95 kPa]-expiratory pressure 8 cmH2O [0.78 kPa]) and a CPAP (10 cmH2O [0.981 kPa]) session. FiO2 was analysed by a probe located in the mask. Minute volume (MV) was measured using a pneumotachograph.

RESULTS

Maximal FiO2 was obtained with CPAP and distal oxygen connection point (67.39 +/- 15.39%). NIPPV achieved higher MV than CPAP. FiO2 was inversely correlated with MV.

CONCLUSIONS

FiO2 obtained while using a NIPPV portable ventilator depends on the ventilatory assistant mode, the oxygen connection point and the MV reached.

Dielectric properties of self-assembled layers of octadecylamine on mica in dry and humid environments

Atomic force microscopy operating in noncontact electrostatic force mode was used to study the interaction of water with films of alkylamines and alkylsilanes on mica. The films efficiently block water adsorption except in exposed mica areas, where it strongly modifies the mobility of surface ions. We also studied the molecular orientation of octadecylamine molecules forming monolayers and multilayer islands. In monolayer films the molecules bind to mica through the amino group, producing a positive contact potential relative to mica (dipole pointing up). In multilayer films the methyl and amino group terminations are exposed in alternating layers that give rise to alternating values of the contact potential. These findings correlate with low and high friction forces measured in the methyl termination and amino terminations.

Cu(II) complexes with a sulfonamide derived from benzoguanamine. Oxidative cleavage of DNA in the presence of H2O2 and ascorbate

Reaction between benzoguanamine (2,4-diamino-6-phenyl-1,3,5-triazine) and 2-mesitylenesulfonyl chloride leads to formation of a sulfonamide able to form two mononuclear Cu(II) complexes with a CuL(2) stoichiometry. The local environment of the metal cation is a distorted octahedron, with two ligands and two solvent molecules; both complexes crystallize in the monoclinic structure, space group P2(1), with Z=2. In the presence of ascorbate/H(2)O(2,) the two complexes significantly cleavage double-strand pUC18 DNA plasmid. Both complexes exhibit more nuclease efficiency that the copper phenantroline complex. From scavenging reactive oxygen studies we conclude that the hydroxyl radical and a singlet oxygen-like entity, such a peroxide copper complex, are the radical species involved in the DNA damage.

[Cervical myelopathy: retrospective analysis of surgical results in 53 cases treated by anterior cervical discectomy and interbody fusion]

PATIENTS AND METHODS

We perform a retrospective analysis of clinical results in 53 consecutive patients surgically treated for cervical myelopathy or myelo-radiculopathy with anterior cervical discectomy and interbody fusion by means of the Cloward procedure.

RESULTS

64.2% of the patients had good outcome as measured by the improvement in one or more grades in the Nurick's scale. No mortality related to the surgical procedure was noted, although 9.4% of the cases suffered neurological deterioration. Correct fusion was achieved in 92.5% of the patients, with a rate of post-surgical kyphosis of 9.4%. Multivariate analysis identified as factors related to the clinical outcome: age (p = 0.008), vascular risk factors (p = 0.031), duration of symptoms (p = 0.002), pre-surgical neurological status (p < 0.001), neuroradiological diagnosis (p = 0.014), intra-medullary high signal intensity changes in T2-weighted images (p = 0.008), prolongation of the central somato-sensory or motor conduction times (p = 0.004) and neurologic complications (p = 0.012)

CONCLUSIONS

Treatment optimisation of the patient suffering cervical spondylotic myelopathy requires individualised evaluation. Prospective randomised studies are needed to answer the questions when and how to operate.

Anchor−GRIND: Filling the Gap between Standard 3D QSAR and the GRid-INdependent Descriptors

The aim of this work is to present the anchor-GRIND methodology. Anchor-GRIND efficiently combines a priori chemical and biological knowledge about the studied compounds with alignment-independent molecular descriptors derived from molecular interaction fields. Such descriptors are particularly useful for series of ligands sharing a common scaffold but with very diverse substituents. The method uses a specific position of the molecular structure (the "anchor point") to compare the spatial distribution of the molecular interaction fields of the substituents. The descriptors produced are more detailed and specific than the original GRIND while still avoiding the bias introduced by the alignment. Three data sets have been studied to demonstrate the usefulness of the anchor-GRIND methodology for 3D-QSAR modeling. The two first data sets respectively include congeneric series of the hepatitis C virus NS3 protease and of the acetylcholinesterase inhibitors. The third data set discriminates between factor Xa inhibitors of high and low affinity. In all the series presented, the models obtained with the anchor-GRIND are statistically sound and easy to interpret.

Accuracy of blood culture for early diagnosis of mediastinitis in febrile patients after cardiac surgery

Postsurgical mediastinitis (PSM) remains a major cause of morbidity and mortality in patients undergoing cardiac surgery procedures. Although prompt diagnosis is crucial in these patients, neither clinical data nor imaging techniques have shown enough sensitivity or specificity for early diagnosis of PSM. The aim of the present study was to assess the validity of blood cultures as a diagnostic test for the early detection of PSM in patients who become febrile after cardiac surgery procedures. During a 4-year period (1999-2002), patients who developed fever (>37.8 degrees C) in the first 60 days after a cardiac surgery procedure were evaluated. Blood cultures were drawn from these patients. PSM was defined as deep infection involving retrosternal tissue and/or the sternal bone directly observed by the surgeon and confirmed microbiologically. Three criteria for positivity of blood cultures were applied: bacteremia, staphylococcal bacteremia, or Staphylococcus aureus bacteremia. For purposes of the analysis, a positive blood culture in patients with PSM was considered a true-positive test and a negative blood culture a false-negative test. Otherwise, in febrile patients without PSM in the postsurgery period, a positive blood culture was considered a false-positive test and a negative blood culture a true-negative test. Blood cultures were drawn from 266 febrile patients in the postsurgery period. PSM occurred in 38 patients (26 cases due to S. aureus, 8 to Staphylococcus epidermidis, 3 to gram-negative enteric bacteria, and one to Pseudomonas aeruginosa). Within the 60-day postsurgical period, blood culture as a diagnostic test was most accurate in patients with S. aureus bacteremia, providing 68% sensitivity, 98% specificity, a positive predictive value of 87%, and a negative predictive value of 95%. If the analysis was limited to the period during which patients are at maximum risk for PSM (day 7-20), the values in patients with S. aureus bacteremia were as follows: 73% sensitivity, 98% specificity, 90% positive predictive value, and 93% negative predictive value. Blood culture is an accurate test for the early diagnosis of PSM in febrile patients after cardiac surgery, particularly in institutions where S. aureus is prevalent in this context. A negative blood culture practically excludes PSM and, during the period of maximum risk for PSM, the presence of S. aureus bacteremia should compel early surgical management.

INFOBIOMED: European Network of Excellence on Biomedical Informatics to support individualised healthcare

INFOBIOMED is an European Network of Excellence (NoE) funded by the Information Society Directorate-General of the European Commission (EC). A consortium of European organizations from ten different countries is involved within the network. Four pilots, all related to linking clinical and genomic information, are being carried out. From an informatics perspective, various challenges, related to data integration and mining, are included.

Continuing education and community pharmacists in Galicia: a study of opinions

AIM OF THE STUDY

To determine the opinions of a volunteer group of community pharmacists concerning general and specific issues related to continuing education.

METHODS

Participants were required to complete questionnaires before and after attendance at a refresher course, and score the relevant options provided on a scale from 0 to 10. The responses of the survey were analyzed to identify preferences and to detect any possible changes in opinion.

MAIN OUTCOME MEASURE

Arithmetic means of pharmacists' opinions.

RESULTS

The teaching methods preferred by the community pharmacists were workshops for resolution of practical cases (9 +/- 0.25 and 8.88 +/- 0.13) and the distance-learning computer programmes (6.74 +/- 0.25 and 8.18 +/- 0.20). In selecting which topics that should be taught, the participants gave the highest ratings to healthcare needs (8.75 +/- 0.14 and 8.57 +/- 0.15) and the demands of the pharmacists (8.15 +/- 0.16 and 8.40 +/- 0.16), with pharmaceutical care being the most requested topic (29 points). Participants preferred courses lasting 20 to 50 hours (6.94 +/- 0.26 and 7.89 +/- 0.16), without preference for schedule.

CONCLUSION

Community pharmacists in Galicia show a great interest in the provision and organization of continuing education activities that meet their needs and expectations.

Oxidative dissolution of chalcopyrite by Acidithiobacillus ferrooxidans analyzed by electrochemical impedance spectroscopy and atomic force microscopy

The microbiological leaching of chalcopyrite (CuFeS(2)) is of great interest because of its potential application to many CuFeS(2)-rich ore materials. However, the efficiency of the microbiological process is very limited because this mineral is one of the most refractory to bacterial attack. Knowledge of bacterial role during chalcopyrite oxidation is very important in order to improve the efficiency of bioleaching operation. The oxidative dissolution of a massive chalcopyrite electrode by Acidithiobacillus ferrooxidans was evaluated by electrochemical impedance spectroscopy (EIS) and atomic force microscopy (AFM). A massive chalcopyrite electrode was utilized in a Tait-type electrochemical cell in acid medium for different immersion times in the presence or absence of bacterium. The differences observed in the impedance diagrams were correlated with the adhesion process of bacteria on the mineral surface.

Comparative Analysis of Putative Agonist-Binding Modes in the Human A1 Adenosine Receptor

A recent study reported a model of the human A(1) adenosine receptor and its agonist binding site, proposing two putative binding modes in the same binding site for the natural agonist, adenosine. The present work investigates the flexibility of this binding site by exhaustive exploration with the natural agonist and with three other adenosine derivatives: N6-cyclopentyladenosine (CPA), 2-chloro-N6-cyclopentyladenosine (CCPA), and 5'-N-ethylcarboxamidoadenosine (NECA). Our aim was to find a common binding mode for agonists that would explain the role in the binding process of the different substitutions allowed at the 2, N6, and 5' positions of adenosine. This problem was addressed through docking simulations, molecular dynamics studies, and estimations of the ligand-binding free energy with both the AUTODOCK scoring function and the linear interaction energy (LIE) approach. The results point to a single receptor-binding position that explains the effects of the different chemical modifications on the adenosine derivatives considered here.

Towards a MIP-based alignment and docking in computer-aided drug design

Structural alignment of ligands in their biological conformation is a crucial step in the building of pharmacophoric models in structure-based drug design. In addition, docking algorithms are limited in some cases by the quality of the scoring functions and the limited flexibility of the environment that the different programs allow. On the other hand, GRID molecular interaction potentials (MIPs) have been used for a long time in 3D-QSAR studies. However, in most of these studies the alignment of the molecules is performed on the basis of geometrical or physico-chemical criteria that differ from the MIPs used in the partial least squares statistical analysis. We have previously developed a method to use the same scoring function for the molecular alignment and for 3D-QSAR studies. This methodology, based on the use of GRID potentials, consists in the weighted averaging of similarities of the relevant MIPs of the molecules to be aligned. Here we present a method to obtain the weights for the different GRID probes in the average based on the structural information on protein-ligand complexes for relevant systems. The method, implemented in MIPSIM, is shown to yield good accuracy in the prediction of the alignments for two systems: a set of three inhibitors of dihydrofolate reductase and a set of fifteen non-nucleoside HIV-1 reverse transcriptase inhibitors (NNRTIs). The smooth GRID potentials are shown to capture the flexible character of the active site, as opposed to traditional docking scoring energy functions.

Incorporating Molecular Shape into the Alignment-free GRid-INdependent Descriptors

The recently introduced GRid-INdependent Descriptors (GRIND) were designed to provide a suitable description of a series of ligands for 3D-QSAR studies not requiring the spatial superimposition of their structures. Despite the proven usefulness of the method, it was recognized that the original GRIND failed to describe appropriately the shape of the ligand molecules, which in some cases plays a major role in ligand-receptor binding. For this reason, the original descriptors have been enhanced with the addition of a molecular shape description based on the local curvature of the molecular surface. The integration of this description into the GRIND allows the generation of 3D-QSAR models able to identify both favorable and unfavorable shape complementarity in a simple and alignment-independent way. The usefulness of the new GRIND-shape description in 3D-QSAR is illustrated using two structure-activity studies: one performed on a set of xanthine-like antagonists of the A(1) adenosine receptor; another performed on a series of Plasmodium falciparum plasmepsin II inhibitors.

[Respiratory infection due to Chlamydia trachomatis in infants. Clinical presentation and outcome in 18 patients]

BACKGROUND

Among other diseases, Chlamydia trachomatis causes epididymitis and prostatitis in men and urethritis, cervicitis and pelvic inflammatory disease in women. In children, it most usually causes conjunctivitis and is also responsible for lower respiratory tract disease, occasionally requiring hospital admission.

OBJECTIVE

To draw attention to this disease, which is usually overlooked and which can be potentially serious.

METHODS

We retrospectively reviewed the medical records of infants aged less than 6 months with symptoms of lower respiratory tract disease in whom C. trachomatis antigen was detected by enzyme immunoassay.

RESULTS

We identified 18 patients with C. trachomatis between 1993 and 2002. Of these, 17 patients required hospital admission and five required monitoring in the pediatric intensive care unit. The mean length of hospital stay was 9.6 days. Three patients were immigrants. The mean age at admission was 6.6 weeks. Apnea occurred in five infants. Chest x-ray showed interstitial infiltrates in five infants. Sixteen patients were treated with erythromycin and all made a complete recovery.

CONCLUSIONS

Although lower respiratory tract disease caused by C. trachomatis is usually managed on an outpatient basis, it sometimes requires hospital admission or even management in the intensive care unit. Therefore, C. trachomatis infection should be ruled out in infants aged less than 6 months with clinical symptoms of lower respiratory tract disease for which no other pathogen can be found.

Sistemas informáticos de soporte a la decisión clínica

This review deals with the historical evolution and methodological basis of computerized medical decision support tools. It also reviews the verification, validation and impact evaluation methods of these systems. The acceptability of them from the health professionals depends on the pro-activity and usefulness of the systems, between other factors. The clinical impact evaluation methods are described in deep detail and the Hunt et al review of 1998 is updated.

Novel approaches for modeling of the A1adenosine receptor and its agonist binding site

The present work describes the building of a human A(1) adenosine receptor (hA(1)AR) model, based on the X-ray crystal structure of bovine rhodopsin, and its use as a basis for the investigation of some important structural characteristics of the receptor. One of the issues investigated was the protonation position of two histidine residues known to influence ligand binding, with protonation of His251 (6.52) in epsilon position and His278 (7.43) in delta position showing the best agreement with experimental evidence. The model was also used to study the position and structural role of water molecules present in the helical bundle. Finally, the binding site location and the ligand docking were investigated using an objective strategy. A suitable site for the binding of the ribose moiety of adenosine was first postulated and further confirmed by means of a novel chemometric strategy based on GRIND descriptors. Using this position as an anchor point, the binding of adenosine was studied by docking and molecular dynamics simulations obtaining two putative binding positions in good agreement with experimental data.

Structuring European biomedical informatics to support individualized healthcare: current issues and future trends

Bioinformatics and Medical Informatics are disciplines that up to now have followed separate development with few contacts and synergies between them in Europe. The elucidation of the human genome has however evidenced the need and the possibilities for a strong synergy between the two. Classical epidemiological and clinical research on the one hand, and genomic research on the other, separately considered, are no longer enough for advancing in the so-called genomic medicine, and a new integrative approach is required. Biomedical Informatics is the emerging discipline that aims to put these two worlds together so that the discovery and creation of novel diagnostic and therapeutic methods is fostered. On the basis of the results of the European Commission-funded BIOINFOMED Study, an INFOBIOMED Network of Excellence has been recently constituted with the main objective of setting a durable structure for the described collaborative approach at a European level. Initially formed by fifteen renowned European organisations, the main objective of the INFOBIOMED network is therefore to enable the reinforcement of European BMI as an integrative discipline.