Anti-endotoxin antibodies consumption in cardiovascular collapse: Pathophysiological concerns

OBJECTIVE

Abnormal endotoxin activity in critically ill patients has been described in the absence of Gram-negative bacterial (GNB) infection. As disease severity seems to be crucial in the detection of this phenomenon, we decided to assess and compare endotoxin exposure in those patients representing the critical situation: septic shock and cardiogenic shock.

DESIGN

Prospective, observational non intervention study.

SETTING

Critical Care Department of a University tertiary hospital.

PATIENTS

Cardiogenic shock (CS) and septic shock (SS) patients.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Follow-up was performed for the first three days. Inflammatory biomarkers (C-reactive protein, procalcitonin and interleuquin-6) and IgM antiendotoxin-core antibodies titter (IgM EndoCAb) were daily analyzed. Sixty-two patients were included; twenty-five patients with SS and thirty-seven with CS. Microbial etiology was established in 23 SS patients (92%) and GNB were present in 13 cases (52%). Although infection was suspected and even treated in 30 CS patients (81%), any episode could be finally confirmed. EndoCAb consumption was more intense in SS patients, although twenty-two CS patients (59.5%) had IgM anti-endotoxin value below 10th percentile range for healthy people. No statistically significant difference in endotoxin exposure was detected between Gram-positive and Gram-negative infections in the SS group. Endotoxin exposure ability to distinguish between SS and CS was moderate (AUC 0.7892, 95% IC: 0.6564-0.9218).

CONCLUSIONS

In the severely ill patient some mechanisms take place allowing endotoxin incursion and therefore blurring the limits of diseases pathophysiology. Our work representatively shows how exposure to endotoxin was not fully capable of distinguishing between CS and SS.

Competency assessment of residents of Intensive Care Medicine through a simulation-based objective structured clinical evaluation (OSCE). A multicenter observational study

OBJECTIVES

The current official model of training in Intensive Care Medicine (ICM) in Spain is based on exposure to experiences through clinical rotations. The main objective was to determine the level of competency (I novice to V independent practitioner) achieved by the residents at the end of the 3rd year of training (R3) in ICM through a simulation-based OSCE. Secondary objectives were: (1) To identify gaps in performance, and (2) To investigate the reliability and feasibility of conducting simulation-based assessment at multiple sites.

DESIGN

Observational multicenter study.

SETTING

Thirteen Spanish ICU Departments.

PARTICIPANTS

Thirty six R3.

INTERVENTION

The participants performed on five, 15-min, high-fidelity crisis scenarios in four simulation centers. The performances were video recorded for later scoring by trained raters.

MAIN VARIABLES OF INTEREST

Via a Delphi technique, an independent panel of expert intensivists identified critical essential performance elements (CEPE) for each scenario to define the levels of competency.

RESULTS

A total of 176 performances were analyzed. The internal consistency of the check-lists were adequate (KR-20 range 0.64-0.79). Inter-rater reliability was strong [median Intraclass Correlation Coefficient across scenarios: 0.89 (0.65-0.97)]. Competency levels achieved by R3 were: Level I (18.8%), II (35.2%), III (42.6%), IV/V (3.4%). Overall, a great heterogeneity in performance was observed.

CONCLUSION

The expected level of competency after one year in the ICU was achieved only in half of the performances. A more evidence-based educational approach is needed. Multiple center simulation-based assessment showed feasibility and reliability as an evaluation method of competency.

TRIAL REGISTRATION

COBALIDATION. NCT04278976. (https://register.

CLINICALTRIALS

gov).

Acceptance and validity of the methods used to implement a competency based medical education programme in an Intensive Care Department of a teaching referral center

OBJECTIVES

1. To determine the satisfaction of tutors and residents with a specific methodology used to implement CoBaTrICE. 2. To determine the reliability and validity of the global rating scales designed ad hoc to assess the performance of the residents for training purposes.

DESIGN

Prospective cohort study.

PARTICIPANTS

All the residents and tutors of the ICU Department of the Hospital Universitario y Politécnico la Fe de Valencia.

INTERVENTION

CoBaTrICE implementation started in March 2016, it was based on: (1) Training the tutors in feedback techniques; (2) Performing multiple objective and structured work based assessments to achieve the competences of the program; and (3) The use of an electronic portfolio to promote learning reflection and to collect the evidence that learning was taking place.

METHODS

The acceptance of CoBaTrICE was explored through a satisfaction survey conducted after 9 months of implementation of the training program. The 15 residents and 5 tutors of the ICU Department were asked about the methodology of the formative assessments, the quality of the feedback, self-learning regulation and the electronic portfolio usefulness. The validity of the global rating scales was assessed through the tests alfa de Cronbach, reliability and generalizability indexes, and intraclass correlation coefficient.

RESULTS

The implementation of CoBaTrICE was satisfactory in all the dimensions studied. The global rating scales used for formative purposes showed reliability and validity.

CONCLUSIONS

The methodology used to implement CoBaTrICE was highly valued by tutors and residents. The global rating scales used for formative purposes showed reliability and validity.

Haemodialysis significantly reduces serum levetiracetam levels inducing epileptic seizures: Case report

WHAT IS KNOWN AND OBJECTIVE

Levetiracetam is used in the treatment of some forms of epilepsy. In renal impairment and patients on chronic haemodialysis, dose adjustment is required. We report a case.

CASE DESCRIPTION

This case report describes a woman on levetiracetam treatment who presented with generalized tonic-clonic seizures during a haemodialysis session. We report on treatment adjustment and on the impact of dialysis on levetiracetam levels.

WHAT IS NEW AND CONCLUSION

Haemodialysis reduces serum levetiracetam concentration and can lead to subtherapeutic levels. Close monitoring is necessary when dialysis is used on patients receiving anticonvulsant drugs that are extensively eliminated by the procedure.

Sulfur Groups Improve the Performance of Triazole- and Triazolium-Based Interaction Units in Anion Binding

An NMR comparative study of 1,2,3-triazole and triazolium anion recognition units containing sulfoxide, sulfone, and sulfoximine groups at C₄ unveils an enhancement in binding ability up to ≈1 kcal/mol in acetone-d₆ correlated with a theoretical increase of H₅ acidity. DFT calculations provide insight into binding modes in line with experimental data for these receptors.

Unique solubility of polyoxoniobate salts in methanol: coordination to cations and POM methylation

In methanolic solutions of A₄[{LM′}₂M₆O₁₉] ({LM′} = {Cp*Rh}²⁺, {Cp*Ir}²⁺, {(C₆H₆)Ru}²⁺; M = Nb, Ta; A = Na, K) formation of methoxo complexes [{LM′}₂M₆O_19−n(OMe)n] (n = 1–3) and coordination of CH₃OH to A⁺ take place.

Platinum polyoxoniobates

Coordination of {Pt(OH)₂}²⁺ fragments to Lindqvist type hexaniobates

Grafting {Cp*Rh}2+ on the surface of Nb and Ta Lindqvist-type POM

Structure of a new hybrid organometallic-pom complex [trans-{Cp*Rh}₂M₆O₁₉]⁴⁻ (M = Nb, Ta).

Cooperative hydrogen bonding in glyco-oligoamides: DNA minor groove binders in aqueous media

A strategy to create cooperative hydrogen-bonding centers by using strong and directional intramolecular hydrogen-bonding motifs that can survive in aqueous media is presented. In particular, glyco-oligoamides, a family of DNA minor groove binders, with cooperative and non-cooperative hydrogen-bonding donor centers in the carbohydrate residues have been designed, synthesized, and studied by means of NMR spectroscopy and molecular modeling methods. Indeed, two different sugar moieties, namely, β-D-Man-Py-γ-Py-Ind (1; Ind=indole, Man=mannose, Py=pyrrole) and β-D-Tal-Py-γ-Py-Ind (2; Tal=talose), were chosen according to our design. These sugar molecules should present one- or two-directional intramolecular hydrogen bonds. The challenge has been to study the conformation of the glyco-oligoamides at low temperature in physiological media by detecting the exchangeable protons (amide NH and OH resonances) by means of NMR spectroscopic analysis. In addition, two more glyco-oligoamides with non-cooperative hydrogen-bonding centers, that is, β-D-Glc-Py-γ-Py-Ind (3; Glc=glucose), β-D-Gal-Py-γ-Py-Ind (4; Gal=galactose), and the model compounds β-D-Man-Py-NHAc (5) and β-D-Tal-Py-NHAc (6) were synthesized and studied for comparison. We have demonstrated the existence of directional intramolecular hydrogen bonds in 1 and 2 in aqueous media. The unexpected differences in terms of stabilization of the intramolecular hydrogen bonds in 1 and 2 relative to 5 and 6 promoted us to evaluate the influence of CH-π interactions on the establishment of intramolecular hydrogen bonds by using computational methods. Initial binding studies of 1 and 2 with calf-thymus DNA and poly(dA-dT)2 by NMR spectroscopic analysis and molecular dynamics simulations were also carried out. Both new sugar-oligoamides are bound in the minor groove of DNA, thus keeping a stable hairpin structure, as in the free state, in which both intramolecular hydrogen-bonding and CH-π interactions are present.

Carbohydrate recognition at the minor-groove of the self-complementary duplex d(CGCGAATTCGCG)2 by a synthetic glyco-oligoamide

The structure of a neutral glyco-conjugate β-Gal-Py-γ-Py-Ind (1), designed as a probe for analyzing sugar-DNA interactions, when bound to a self-complementary oligonucleotide duplex d(CGCG AATT CGCG)(2) has been deduced by employing (1)H NMR techniques. Analysis of the formed 1:1 complex demonstrated that the glycol ligand is bound in a hairpin-like conformation in which both pyrrole amino acid moieties are stacked, whereas the indole and the sugar residues are spatially close. The binding site is defined by the minor groove formed by the -AATT- stretch. In particular, the -Py-γ-Py- region of the ligand is sited near the A5-A6 oligonucleotide residues, whereas the indole and the sugar rings are next to the T7-T8 base pairs. More relevant, the existence of a variety of intermolecular NOE correlations permitted the close proximity of the sugar to the minor groove to be assessed, thus showing that the binding of the glycoconjugate at the minor groove is the origin of the specificity of the glycoconjugate-DNA interaction. The experimental NMR data have been combined with restrained and unrestrained molecular dynamics calculations, to provide the 3D structure of the complex.

A synthetic lectin for O-linked beta-N-acetylglucosamine

Changing employment: Receptor 1 binds beta-N-acetylglucosaminyl (beta-GlcNAc) up to 100 times more strongly than it does glucose. This synthetic lectin shows affinities similar to wheat germ agglutinin (WGA), a natural lectin used to bind GlcNAc. Remarkably, 1 is more selective than WGA. It favors especially the glycoside unit in glycopeptide 2, a model of the serine-O-GlcNAc posttranslational protein modification.

Carbohydrate-based DNA ligands: sugar-oligoamides as a tool to study carbohydrate-nucleic acid interactions

Sugar-oligoamides have been designed and synthesized as structurally simple carbohydrate-based ligands to study carbohydrate-DNA interactions. The general design of the ligands 1-3 has been done as to favor the bound conformation of Distamycin-type gamma-linked covalent dimers which is a hairpin conformation. Indeed, NMR analysis of the sugar-oligoamides in the free state has indicated the presence of a percentage of a hairpin conformation in aqueous solution. The DNA binding activity of compounds 1-3 was confirmed by calf thymus DNA (ct-DNA) NMR titration. Interestingly, the binding of the different sugar-oligoamides seems to be modulated by the sugar configuration. Semiquantitative structural information about the DNA ligand complexes has been derived from NMR data. A competition experiment with Netropsin suggested that the sugar-oligoamide 3 bind to DNA in the minor groove. The NMR titrations of 1-3 with poly(dA-dT) and poly(dG-dC) suggested preferential binding to the ATAT sequence. TR-NOE NMR experiments for the sugar-oligoamide 3-ct-DNA complex both in D(2)O and H(2)O have confirmed the complex formation and given information on the conformation of the ligand in the bound state. The data confirmed that the sugar-oligoamide ligand is a hairpin in the bound state. Even more relevant to our goal, structural information on the conformation around the N-glycosidic linkage has been accessed. Thus, the sugar asymmetric centers pointing to the NH-amide and N-methyl rims of the molecule have been characterized.

Preparation and Properties of the Full Series of Cuboidal Clusters [MoxW4-xSe4(H2O)12]n+ (n = 4−6) and Their Derivatives

Hydrothermal reactions between incomplete cuboidal cluster aqua complexes [M3Q4(H2O)9]4+ and M(CO)6 (M = Mo, W; Q = S, Se) offer easy access to the corresponding cuboidal clusters M4Q4. The complete series of homometal and mixed Mo/W clusters [Mo(x)W4-xQ4(H2O)12]n+ (x = 0-4, n = 4-6) has been prepared. Upon oxidation of the mixed-metal clusters, it is the W atom which is lost, allowing selective preparation of new trinuclear clusters [Mo2WSe4(H2O)9]4+ and [MoW2Se4(H2O)9]4+. The aqua complexes were converted by ligand exchange reactions into dithiophosphato and thiocyanato complexes, and crystal structures of [W4S4((EtO)2PS2)6], [MoW3S4((EtO)2PS2)6], [Mo4Se4((EtO)2PS2)6], [W4Se4((i-PrO)2PS2)6], and (NH4)6[W4Se4(NCS)12]-4H20 were determined. Cyclic voltammetry was performed on [Mo(x)W4-xCO4(H2O)12]n+, showing reversible redox waves 6+/5+ and 5+/4+. The lower oxidation states are more difficult to access as the number of W atoms increases. The [Mo2WSe4(H2O)9]4+ and [MoW2Se4(H2O)9]4+ species were derivatized into [Mo2WSe4(acac)3(py)3]+ and [MoW2Se4(acac)3(py)3]+, which were also studied by CV. When appropriate, the products were also characterized by FAB-MS and NMR (31P, 1H) data.

Hydrogen-Bonding Cooperativity: Using an Intramolecular Hydrogen Bond To Design a Carbohydrate Derivative with a Cooperative Hydrogen-Bond Donor Centre

Neighbouring groups can be strategically located to polarise HO.OH intramolecular hydrogen bonds in an intended direction. A group with a unique hydrogen-bond donor or acceptor character, located at hydrogen-bonding distance to a particular OH group, has been used to initiate the hydrogen-bond network and to polarise a HO.OH hydrogen bond in a predicted direction. This enhanced the donor character of a particular OH group and made it a cooperative hydrogen-bond centre. We have proved that a five-membered-ring intramolecular hydrogen bond established between an amide NH group and a hydroxy group (1,2-e,a), which is additionally located in a 1,3-cis-diaxial relationship to a second hydroxy group, can be used to select a unique direction on the six-membered-ring intramolecular hydrogen bond between the two axial OH groups, so that one of them behaves as an efficient cooperative donor. Talose derivative 3 was designed and synthesised to prove this hydrogen-bonding network by NMR spectroscopy, and the mannopyranoside derivatives 1 and 2 were used as models to demonstrate the presence in solution of the 1,2-(e,a)/five-membered-ring intramolecular hydrogen bond. Once a well-defined hydrogen-bond is formed between the OH and the amido groups of a pyranose ring, these hydrogen-bonding groups no longer act as independent hydrogen-bonding centres, but as hydrogen-bonding arrays. This introduces a new perspective on the properties of carbohydrate OH groups and it is important for the de novo design of molecular recognition processes, at least in nonpolar media. Carbohydrates 1-3 have shown to be efficient phosphate binders in nonpolar solvents owing to the presence of cooperative hydroxy centres in the molecule.

A prototype calix[4]arene-based receptor for carbohydrate recognition containing peptide and phosphate binding groups

A novel class of macrobicyclic receptors for carbohydrate recognition based on upper rim, peptide-bridged calix[4]arenes has been designed and synthesized. Receptor 12, in which a charged phosphate group cooperates with peptide hydrogen-bonding donor and acceptor groups in the binding process, is the most efficient and selective in the complexation of simple carbohydrate derivatives. The selectivity observed is toward beta-glucoside 13a, which is better bound (DeltaG degrees = 19.6 kJ mol(-)(1)) compared to the corresponding alpha anomer 13b (DeltaG degrees = 17.0 kJ mol(-)(1)) and to the beta-galactoside 13c (DeltaG degrees = 17.7 kJ mol(-)(1)) in CDCl(3). A substantial drop in the stability constant is observed by esterification of the phosphate group in the host 12 or by alkylation of the OH groups in the 2 and 3 positions in the beta-glucoside and beta-galactoside derivatives. On the basis of a careful analysis of the (1)H NMR data available, a binding mode of the beta-octylglucoside 13a to receptor 12 is proposed.

Experimental evidence for the existence of non-exo-anomeric conformations in branched oligosaccharides: NMR analysis of the structure and dynamics of aminoglycosides of the neomycin family

It is commonly known that the exo-anomeric effect is a major factor governing the conformational behavior of naturally occurring oligosaccharides. Conformational flexibility in these molecules mainly concerns the aglycon psi angle since phi is restricted by this stereo-electronic effect. In fact, to the best of our knowledge no case of a natural glycoside adopting a non-exo-anomeric conformation in solution has yet been reported. With respect to the flexibility among naturally occurring carbohydrates, branched type oligosaccharides including sugar residues glycosidated at contiguous positions (such as blood type carbohydrate antigens Lewis X) have been considered as the paradigm of rigid saccharides--the rigidity being enhanced by van der Waals interactions. Herein, we demonstrate unambiguously that both common beliefs are not to be generalized. For example in neomycin B, a branched oligosaccharide antibiotic, a large number of non-exo-anomeric conformations was detected in solution for the first time in naturally occurring sugars. This unusual behavior is attributed to branching. Here, polar contacts between non-vicinal sugar units lead to an enhanced flexibility of the ribose glycosidic torsion phi. The influence of sugar flexibility on RNA recognition will also be discussed.

Experimental evidence for the existence of non-exo-anomeric conformations in branched oligosaccharides: the neomycin-B case

For the first time in natural O-glycosides, a large amount of non-exo-anomeric conformation is experimentally detected, in solution.

Vibrational coupling as diagnostic for intramolecular hydrogen bonds of carbohydrates in aqueous solution

The coupling of nuC-O and deltaO-D vibrations in the 1200-900 cm(-1) IR range leads to band shifting in opposite directions, which provides information on intramolecular hydrogen bonding of carbohydrates in aqueous solution. The aqueous solution IR spectra of 2-acetamide-1,6-anhydro-2-deoxy-D-glucopyranose and cis-1,2-cyclopentanediol and tetrahydrofuran-ethanol mixtures are reported. Frequency upshifting upon deuteration is observed for the nuC-O bands of both a hydrogen bond acceptor and donor in ether-hydroxyl and hydroxyl-hydroxyl contacts. The 1200-900 cm(-1) range can be used to reveal the presence of intramolecular hydrogen bonds in aqueous carbohydrates, unlike the OH stretching region, which cannot be used in this sense due to carbohydrate band masking by the strong nuOH IR absorption of water.

The relevance of carbohydrate hydrogen-bonding cooperativity effects: a cooperative 1,2-trans-diaxial diol and amido alcohol hydrogen-bonding array as an efficient carbohydrate-phosphate binding motif in nonpolar media

Carbohydrates with suitably positioned intramolecularly hydrogen-bonded hydroxyl and amide groups have the potential to act as efficient bidentate phosphate binders by taking advantage of sigma- and/or ,sigma,pi-H-bonding cooperativity in nonpolar solvents. Donor-donor 1,2-trans-diaxial amido alcohol (1) and diol (3), in which one of the donor centres is cooperative, are very efficient carbohydrate-phosphate binding motifs. We have proven and quantified the key role of hydrogen-bonding centres indirectly involved in complexation, which serve to generate an intramolecular H-bond (six-membered cis H-bond) in 1 and 3. This motif enhances the donor nature of the H-bonding centres that are directly involved in complexation. A comparison of the thermodynamic parameters of the complexes formed between phosphate and a cooperative (1-Phos) or anti-cooperative (2-Phos) bidentate H-bonded motif of a carbohydrate has allowed us to quantify the energetic advantage of H-bonding cooperativity in CDCl3 and CDCl3/CCl4 (1:1.3) (Delta Delta G degrees=-2.2 and -2.0 kcal mol(-1), respectively). The solvent dependences of the entropy and enthalpy contributions to binding provide a valuable example of the delicate balance between entropy and enthalpy that can arise for a single process, providing effective cooperative binding in terms of Delta G degrees.