[Recommendations of the Working Groups from the Spanish Society of Intensive and Critical Care Medicine and Coronary Units (SEMICYUC) for the management of adult critically ill patients in the coronavirus disease (COVID-19)]. / Recomendaciones de «hacer¼ y «no hacer¼ en el tratamiento de los pacientes críticos ante la pandemia por coronavirus causante de COVID-19 de los Grupos de Trabajo de la Sociedad Española de Medicina Intensiva, Crítica y Unidades Coronarias (SEMICYUC).

On March 11, 2020, the Director-General of the World Health Organization (WHO) declared the disease caused by SARS-CoV-2 (COVID-19) as a pandemic. The spread and evolution of the pandemic is overwhelming the healthcare systems of dozens of countries and has led to a myriad of opinion papers, contingency plans, case series and emerging trials. Covering all this literature is complex. Briefly and synthetically, in line with the previous recommendations of the Working Groups, the Spanish Society of Intensive, Critical Medicine and Coronary Units (SEMICYUC) has prepared this series of basic recommendations for patient care in the context of the pandemic.

Outcomes of very elderly trauma ICU patients. Results from the Spanish trauma ICU registry.

OBJECTIVE: To analyze outcomes and factors related to mortality among very elderly trauma patients admitted to intensive care units (ICUs) participating in the Spanish trauma ICU registry. DESIGN: A multicenter nationwide registry. Retrospective analysis. November 2012-May 2017. SETTING: Participating ICUs. PATIENTS: Trauma patients aged ≥80 years. INTERVENTIONS: None. MAIN VARIABLES OF INTEREST: The outcomes and influence of limitation of life sustaining therapy (LLST) were analyzed. Comparisons were established using the Wilcoxon test, Chi-squared test or Fisher's exact test as appropriate. Multiple logistic regression analysis was performed to analyze variables related to mortality. A p-value <0.05 was considered statistically significant. RESULTS: The mean patient age was 83.4±3.3 years; 281 males (60.4%). Low-energy falls were the mechanisms of injury in 256 patients (55.1%). The mean ISS was 20.5±11.1, with a mean ICU stay of 7.45±9.9 days. The probability of survival based on the TRISS methodology was 69.8±29.7%. The ICU mortality rate was 15.5%, with an in-hospital mortality rate of 19.2%. The main cause of mortality was intracranial hypertension (42.7%). The ISS, the need for first- and second-tier measures to control intracranial pressure, and being admitted to the ICU for organ donation were independent mortality predictors. LLST was applied in 128 patients (27.9%). Patients who received LLST were older, with more severe trauma, and with more severe brain injury. CONCLUSIONS: Very elderly trauma ICU patients presented mortality rates lower than predicted on the basis of the severity of injury.

Epidemiology of severe trauma in Spain. Registry of trauma in the ICU (RETRAUCI). Pilot phase. / Epidemiología del trauma grave en España. REgistro de TRAuma en UCI (RETRAUCI). Fase piloto.

OBJECTIVE: To describe the characteristics and management of severe trauma disease in Spanish Intensive Care Units (ICUs). Registry of trauma in the ICU (RETRAUCI). Pilot phase. DESIGN: A prospective, multicenter registry. SETTING: Thirteen Spanish ICUs. PATIENTS: Patients with trauma disease admitted to the ICU. INTERVENTIONS: None. MAIN VARIABLES OF INTEREST: Epidemiology, out-of-hospital attention, registry of injuries, resources utilization, complications and outcome were evaluated. RESULTS: Patients, n=2242. Mean age 47.1±19.02 years. Males 79%. Blunt trauma 93.9%. Injury Severity Score 22.2±12.1, Revised Trauma Score 6.7±1.6. Non-intentional in 84.4% of the cases. The most common causes of trauma were traffic accidents followed by pedestrian and high-energy falls. Up to 12.4% were taking antiplatelet medication or anticoagulants. Almost 28% had a suspected or confirmed toxic influence in trauma. Up to 31.5% required an out-of-hospital artificial airway. The time from trauma to ICU admission was 4.7±5.3hours. At ICU admission, 68.5% were hemodynamically stable. Brain and chest injuries predominated. A large number of complications were documented. Mechanical ventilation was used in 69.5% of the patients (mean 8.2±9.9 days), of which 24.9% finally required a tracheostomy. The median duration of stay in the ICU and in hospital was 5 (range 3-13) and 9 (5-19) days, respectively. The ICU mortality rate was 12.3%, while the in-hospital mortality rate was 16.0%. CONCLUSIONS: The pilot phase of the RETRAUCI offers a first impression of the epidemiology and management of trauma disease in Spanish ICUs.

Structural characterization of HBXIP: the protein that interacts with the anti-apoptotic protein survivin and the oncogenic viral protein HBx.

Hepatitis B X-interacting protein (HBXIP) is a ubiquitous protein that was originally identified as a binding partner of the hepatitis B viral protein HBx. HBXIP is also thought to serve as an anti-apoptotic cofactor of survivin, promoting the suppression of pro-caspase-9 activation. Here were port the crystal structure of the shortest isoform of HBXIP (91 aa long,∼11 kDa) at 1.5 Å resolution. HBXIP crystal shows a monomer per asymmetric unit, with a profilin-like fold which is common to a super family of proteins, the Roadblock/LC7 domain family involved in protein-protein interactions. Based on this fold, we propose that HBXIP can form a dimer that can indeed be found in the crystal when symmetric molecules are generated around the asymmetric unit. This dimer shows an extended ß-sheet area formed by 10 anti-parallel ß-strands from both subunits. Another interesting aspect of the proposed HBXIP dimer interface is the presence of a small leucine zipper between the two α2 helices of each monomer. In solution, the scattering curve obtained by small-angle X-ray scattering for the sample used for crystallization indicates that the protein is dimeric form in solution. The fit between the experimental small angle X-ray scattering curve and the back calculated curves for two potential crystal dimers shows a significant preference for the Roadblock/LC7 fold dimer model. Moreover, the HBXIP crystal structure represents a step towards understanding the cellular role of HBXIP.

The three-dimensional structure of VIM-2, a Zn-beta-lactamase from Pseudomonas aeruginosa in its reduced and oxidised form.

The crystal structures of the universally widespread metallo-beta-lactamase (MBL) Verona integron-encoded MBL (VIM)-2 from Pseudomonas aeruginosa have been solved in their native form as well as in an unexpected oxidised form. This carbapenem-hydrolysing enzyme belongs to the so-called B1 subfamily of MBLs and shares the folding of alpha beta/beta alpha sandwich, consisting of a core of beta-sheet surrounded by alpha-helices. Surprisingly, it showed a high tendency to be strongly oxidised at the catalytic cysteine located in the Cys site, Cys221, which, in the oxidised structure, becomes a cysteinesulfonic residue. Its native structure was obtained only in the presence of Tris(2-carboxyethyl)phosphine. This oxidation might be a consequence of a lower affinity for the second Zn located in the Cys site that would also explain the observed susceptibility of VIM-2 to chelating agents. This modification, if present in nature, might play a role in catalytic down-regulation. Comparison between native and oxidised VIM-2 and a predicted model of VIM-1 (which shows one residue different in the Cys site compared with VIM-2) is performed to explain the different activities and antibiotic specificities.

Human kinetochore-associated kinesin CENP-E visualized at 17 A resolution bound to microtubules.

The highly dynamic process of cell division is effected, in part, by molecular motors that generate the forces necessary for its enactment. Several members of the kinesin superfamily of motor proteins are implicated in mitosis, such as CENP-E, which plays essential roles in cell division, including association with the kinetochore to stabilize attachment of chromosomes to microtubules prior to and during their separation. Neither the functional assembly state of CENP-E nor its direction of motion along the polar microtubule are certain. To determine the mode of interaction between CENP-E and microtubules, we have used cryo-electron microscopy to visualize CENP-E motor domains complexed with microtubules and calculated a density map of the complex to 17 A resolution by combining helical and single-particle reconstruction methods. The interface between the motor domain and microtubules was modeled by docking atomic-resolution models of the subunits into the cryoEM density map. Our results support a plus end motion for CENP-E, consistent with features of the crystallographic structure. Despite considerable functional differences from the monomeric transporter kinesin KIF1A and the oppositely directed ncd kinesin, CENP-E appears to share many features of the intermolecular interactions, suggesting that differences in motor function are governed by small variations in the loops at the microtubule interface.

Three-dimensional structure of FEZ-1, a monomeric subclass B3 metallo-beta-lactamase from Fluoribacter gormanii, in native form and in complex with D-captopril.

The beta-lactamases are involved in bacterial resistance to penicillin and related compounds. Members of the metallo-enzyme class are now found in many pathogenic bacteria and are thus becoming of major clinical importance. The structures of the Zn-beta-lactamase from Fluoribacter gormanii (FEZ-1) in the native and in the complex form are reported here. FEZ-1 is a monomeric enzyme, which possesses two zinc-binding sites. These structures are discussed in comparison with those of the tetrameric L1 enzyme produced by Stenotrophomonas maltophilia. From this analysis, amino acids involved in the oligomerization of L1 are clearly identified. Despite the similarity in fold, the active site of FEZ-1 was found to be significantly different. Two residues, which were previously implicated in function, are not present in L1 or in FEZ-1. The broad-spectrum substrate profile of Zn-beta-lactamases arises from the rather wide active-site cleft, where various beta-lactam compounds can be accommodated.

Purification of the Caenorhabditis elegans transposase Tc1A refolded during gel filtration chromatography.

Full-length recombinant transposase Tc1A from Caenorhabditis elegans (343 amino acids) expressed in Escherichia coli BL21 in inclusion bodies has been purified in a high yield in a soluble form. The procedure includes denaturation of the inclusion bodies followed by refolding of the Tc1A protein by gel filtration. This last step is absolutely crucial to give a high yield of soluble and active protein since it allows the physical separation of the aggregates from intermediates that give rise to correctly refolded protein. This step is very sensitive to the concentration of protein. Good yields of refolded protein are obtained by refolding 2 to 12 mg of denatured protein. The other purification steps involve the initial use of gel filtration under denaturing conditions and a final step of ion-exchange chromatography. Biological activity of the purified protein was confirmed in an in vitro transposon excision assay and its DNA-binding capacity by UV crosslinking. This new Tc1A purification procedure gives a yield of 12-16 mg/liter E. coli culture, in a form suitable for crystallization studies.

The three-dimensional structure of a class-Pi glutathione S-transferase complexed with glutathione: the active-site hydration provides insights into the reaction mechanism.

The structure of mouse liver glutathione S-transferase P1-1 complexed with its substrate glutathione (GSH) has been determined by X-ray diffraction analysis. No conformational changes in the glutathione moiety or in the protein, other than small adjustments of some side chains, are observed when compared with glutathione adduct complexes. Our structure confirms that the role of Tyr-7 is to stabilize the thiolate by hydrogen bonding and to position it in the right orientation. A comparison of the enzyme-GSH structure reported here with previously described structures reveals rearrangements in a well-defined network of water molecules in the active site. One of these water molecules (W0), identified in the unliganded enzyme (carboxymethylated at Cys-47), is displaced by the binding of GSH, and a further water molecule (W4) is displaced following the binding of the electrophilic substrate and the formation of the glutathione conjugate. The possibility that one of these water molecules participates in the proton abstraction from the glutathione thiol is discussed.

On the reaction mechanism of class Pi glutathione S-transferase.

Theoretical calculations were performed to examine the ionization of the phenolic group of Tyr7 and the thiol group of glutathione in aqueous solution and in the protein class-pi glutathione S-transferase (GST-Pi). Three model systems were considered for simulations in the protein environments the free enzyme, the complex between glutathione and the enzyme, and the complex between 1-chloro-2.4-dinitrobenzene, glutathione, and the enzyme. The structures derived from Molecular Dynamics simulations were compared with the crystallographic data available for the complex between the inhibitor S-(p-nitrobenzyl)glutathione and GST-Pi, the glutathione-bound form of GST-Pi, and the free enzyme carboxymethylated in Cys47. Free-energy perturbation techniques were used to determine the thermodynamics quantities for ionization of the phenol and thiol groups. The functional implications of Tyr7 in the activation of the glutathione thiol group are discussed in the light of present results, which in agreement with previous studies suggest that Tyr7 in un-ionized form contributes to the catalytic process of glutathione S-transferase, the thiolate anion being stabilized by hydrogen bond with Tyr7 and by interactions with hydrating water molecules.

The three-dimensional structure of human procarboxypeptidase A2. Deciphering the basis of the inhibition, activation and intrinsic activity of the zymogen.

The three-dimensional structure of human procarboxypeptidase A2 has been determined using X-ray crystallography at 1.8 A resolution. This is the first detailed structural report of a human pancreatic carboxypeptidase and of its zymogen. Human procarboxypeptidase A2 is formed by a pro-segment of 96 residues, which inhibits the enzyme, and a carboxypeptidase moiety of 305 residues. The pro-enzyme maintains the general fold when compared with other non-human counterparts. The globular part of the pro-segment docks into the enzyme moiety and shields the S2-S4 substrate binding sites, promoting inhibition. Interestingly, important differences are found in the pro-segment which allow the identification of the structural determinants of the diverse activation behaviours of procarboxypeptidases A1, B and A2, particularly of the latter. The benzylsuccinic inhibitor is able to diffuse into the active site of procarboxypeptidase A2 in the crystals. The structure of the zymogen-inhibitor complex has been solved at 2.2 A resolution. The inhibitor enters the active site through a channel formed at the interface between the pro-segment and the enzyme regions and interacts with important elements of the active site. The derived structural features explain the intrinsic activity of A1/A2 pro-enzymes for small substrates.

Characterisation and preliminary X-ray diffraction analysis of human pancreatic procarboxypeptidase A2.

Human procarboxypeptidase A2 has been expressed in a Pichia pastoris heterologous system and purified by hydrophobic interaction and anion exchange chromatographies. The hydrolytic action of carboxypeptidase A2 on peptide substrates with different lengths and residues at the C-terminus was analysed, and a preference towards long substrates with aromatic amino acids in their C-terminal end, particularly tryptophan, was found; with such substrates its activity is similar or higher than that of bovine carboxypeptidase A1. Procarboxypeptidase A2 has been crystallised using a vapour diffusion approach; the crystals obtained belong to the monoclinic system, spacegroup P2(1), and present one procarboxypeptidase A2 molecule per asymmetric unit. The crystals diffract beyond 1.8 A resolution and are suitable for detailed X-ray analysis.

Three-dimensional crystal structure of the A-tract DNA dodecamer d(CGCAAATTTGCG) complexed with the minor-groove-binding drug Hoechst 33258.

The molecular structure of the DNA A-tract dodecamer d(CGCAAATTTGCG) complexed with the drug Hoechst 33258 has been determined by X-ray diffraction analysis. The Hoechst molecule binds in the DNA minor groove covering the sequence AATTT of the central A-tract, with the piperazine group close to one of the GC regions. The drug molecule makes two three-centered hydrogen bonds from the nitrogen atoms of the benzimidazole rings to the N3 and O2 atoms of the DNA bases. Although a high propeller twist is observed in the A-tract, only one unsymmetrical three-centered hydrogen bond is present in the DNA major groove. The structure is compared with other minor-groove-binding drug complexes and the influence of these drugs on DNA A-tracts is discussed.

Molecular structure at 1.8 A of mouse liver class pi glutathione S-transferase complexed with S-(p-nitrobenzyl)glutathione and other inhibitors.

The three-dimensional crystal structure of pi class glutathione S-transferase YfYf from mouse liver complexed with the inhibitor S-(p-nitrobenzyl)glutathione has been determined at 1.8 A resolution by X-ray diffraction. In addition two complexes with glutathione sulphonic acid and S-hexylglutathione have been determined at resolutions of 1.9 and 2.2 A, respectively. The high resolution of the S-(p-nitrobenzyl)glutathione complex allows a detailed analysis of the active site including the hydrophobic (H-) subsite. The nitrobenzyl moiety occupies a hydrophobic pocket with its aromatic ring sandwiched between Phe8 and the hydroxyl group of Tyr108. An insertion of two residues Gly41 and Leu42, with respect to the pig enzyme, splits helix alpha B into an alpha-helix and a 3(10) helix. Water bridges between carbonyl oxygen atoms of the alpha-helix at its C terminus and the amide NH groups of the 3(10) helix at its N terminus provide structural continuity between these two secondary elements. Tyr7 appears to be the only residue close to the sulphur atom of glutathione, while three conserved water molecules lie in the surrounding area in all complexes. The enzyme mechanism is discussed on the basis of the structural analysis.