[Respiratory infections caused by Aspergillus spp. in critically ill patients admitted to the intensive care units]. / Infecciones respiratorias por Aspergillus spp. en pacientes críticos ingresados en unidades de cuidados intensivos.

UNLABELLED: The presence of respiratory fungal infection in the critically ill patient is associated with high morbidity and mortality. OBJECTIVES: To assess the incidence of respiratory infection caused by Aspergillus spp. independently of the origin of infection in patients admitted to Spanish ICUs, as well as to describe the rates, characteristics, outcomes and prognostic factors in patients with this type of infection. MATERIAL AND METHODS: An observational, retrospective, open-label and multicenter study was carried out in a cohort of patients with respiratory infection caused by Aspergillus spp. admitted to Spanish ICUs between 2006 and 2012 (months of April, May and June), and included in the ENVIN-HELICS registry (108,244 patients and 825,797 days of ICU stay). Variables independently related to in-hospital mortality were identified by multiple logistic regression analysis. RESULTS: A total of 267 patients from 79 of the 198 participating ICUs were included (2.46 cases per 1000 ICU patients and 3.23 episodes per 10,000 days of ICU stay). From a clinical point of view, infections were classified as ventilator-associated pneumonia in 93 cases (34.8%), pneumonia unrelated to mechanical ventilation in 120 cases (44.9%), and tracheobronchitis in 54 cases (20.2%). The study population included older patients (mean 64.8±17.1 years), with a high severity level (APACHE II score 22.03±7.7), clinical diseases (64.8%) and prolonged hospital stay before the identification of Aspergillus spp. (median 11 days), transferred to the ICU mainly from hospital wards (58.1%) and with high ICU (57.3%) and hospital (59.6%) mortality rates, exhibiting important differences depending on the type of infection involved. Independent mortality risk factors were previous admission to a hospital ward (OR=7.08, 95%CI: 3.18-15.76), a history of immunosuppression (OR=2.52, 95%CI: 1.24-5.13) and severe sepsis or septic shock (OR=8.91, 95%CI: 4.24-18.76). CONCLUSIONS: Respiratory infections caused by Aspergillus spp. in critically ill patients admitted to the ICU in Spain are infrequent, and affect a very selected group of patients, characterized by high mortality and conditioned by non-modifiable risk factors.

[Impact of the premature discharge on hospital mortality after a stay in an intensive care unit]. / Impacto de las altas no programadas en la mortalidad hospitalaria tras la estancia en una unidad de cuidados intensivos.

OBJECTIVE: To determine the frequency and to evaluate the relationship between premature discharge and post-ICU hospital mortality. DESIGN: A prospective registry was made for patients admitted during six consecutive years, performing a retrospective analysis of the data on the first admission of ICU survivors. SETTING: A 10-bed general ICU in a 540-bed tertiary-care community hospital. PATIENTS: 1,521 patients with an ICU stay longer than 12 hours, discharged alive to wards with known hospital outcome. INTERVENTIONS: None. MAIN VARIABLES: We recorded the patient data, including types of ICU discharge, normal or premature, and studying their relationship with post-ICU hospital mortality. The types of ICU discharge were also evaluated versus ICU readmission rate and post-ICU length of stay. RESULTS: There were 165 patients (10.8%) with premature discharge. Mortality rate was 11.6% (176 patients). The factors related with mortality were withdrawal and limitation of life-sustaining treatments (OR=14.02 [4.6-42.6]), readmissions to ICU (OR=3.46 [1.76-6.78]), premature discharge (OR=2.6 [1.06-4.41]), higher organ failure score on discharge from the ICU (OR=1.16 [1.01-1.32]) and age (OR=1.03 [1.01-1.05]). Readmission rates and post-ICU length of stay were similar among patients with premature and normal discharge (7.3% vs. 8.2%, P=.68 and 16.7±16.7 days vs. 18.7±21.3 days, respectively, P=.162). CONCLUSIONS: Premature discharges appear to be common in our setting and have a significant impact on mortality. Types of ICU discharge do not seem to be related with other outcome variables in the hospital care of critically ill patients.

A complex plant cell wall polysaccharide: rhamnogalacturonan II. A structure in quest of a function.

Walls of growing plants are extremely complex and sophisticated composite materials incorporating a dynamic assembly of polysaccharides, proteins and phenolics. Among the polysaccharides, the pectins encompass a group of acidic heteropolysaccharides; they offer a repertoire of structural complexity associated with the occurrence of, at least, three specific domains. Whereas most of these domains are notable for their structural heterogeneity, one of these, the so-called rhamnogalacturonan II (RG-II) exhibits a remarkable conservation throughout the plant kingdom. RG-II is thought to be the most complex plant polysaccharide on Earth (MW 5-10 kDa); its occurrence and strong conservation may indicate that it plays a major role in the structure and growth of higher plants. The present paper examines the most recent findings related to the occurrence, the structures, biosynthesis, biological role and properties, functional properties and technological applications of RG-II. Particular emphasis is given on the description of the three-dimensional structures of RG-II, in its monomeric and dimeric form as elucidated from the concerted investigations throughout 800 MHz NMR spectroscopy, light scattering, atomic force microscopy along with molecular mechanics and dynamics. Some attempts of deciphering of the structural role that RG-II may play in the cell wall of growing plants are presented.

Studies on the solution conformation and dynamics of a polysaccharide from Sinorhizobium fredii HH103 and its monosaccharide repeating unit.

The conformational behavior of the homopolysaccharide isolated from Sinorhizobium fredii HH103 and its monosaccharide repeating unit (5-acetamido-3,5,7,9-tetradeoxy-7-(3-hydroxybutyramido)-L-glycero- L- manno-nonulosonic acid) was analyzed by nuclear magnetic resonance (NMR) spectroscopy and extensive molecular dynamics simulations (MD). The results indicate that the glycosidic linkages and lateral chains may adopt a variety of conformations. MD simulations using the generalized Born solvent-accessible surface area (GB/SA) continuum solvent model for water and the MM3* force field provide a population distribution of conformers that satisfactorily agrees with the experimental NMR data for the torsional degrees of freedom of the molecule.

Structural analysis of the exopolysaccharide produced by Pediococcus damnosus 2.6.

The exopolysaccharide produced by a ropy strain of Pediococcus damnosus (2.6) in a semi-defined medium was found to be an homopolymer composed of D-glucose. On the basis of monosaccharide and methylation analysis, 1H, 13C, 1D and 2D NMR experiments the polysaccharide was shown to consist of repeating units with the following structure. [sequence: see text]

Structural analysis of the exopolysaccharides produced by Lactobacillus spp. G-77.

The exopolysaccharide produced by a ropy strain of Lactobacillus spp. G-77 in a semi-defined medium, was found to be a mixture of two homopolymers composed of D-Glc. The two poly-saccharides were separated and, on the basis of monosaccharide and methylation analyses, 1H, 13C, 1D and 2D NMR experiments, one of the polysaccharides was shown to be a 2-substituted-(1-3)-beta-D-glucan, identical to that described for the EPS from Pediococcus damnosus 2.6 (M.T. Dueñas-Chasco, M.A. Rodríguez-Carvajal, P. Tejero-Mateo, G. Franco-Rodríguez, J. L. Espartero, A. Irastorza-Iribar, and A.M. Gil-Serrano, Carbohydr. Res., 303 (1997) 453-458), and the other polysaccharide was shown to consist of repeating units with the following structure [formula: see text]

Growth and exopolysaccharide (EPS) production by Oenococcus oeni I4 and structural characterization of their EPSs.

AIMS: To study the influence of medium constituents on growth, and exopolysaccharide (EPS) production by a strain of Oenococcus oeni. The structure of one of the EPSs has also been characterized. METHODS AND RESULTS: EPS concentration was estimated by the phenol/sulfuric acid method. After purification and fractionation of crude EPSs, the sugar composition was determined by GLC-MS of the TMS methyl glycosides. The major polysaccharide is 2-substituted-(1-3)-beta-D-glucan. This structure was determined by methylation analysis and conventional (1)H- and (13)C-nuclear magnetic resonance spectroscopy. In addition, O. oeni synthesized two heteropolysaccharides, although a lesser proportion, constituted by galactose and glucose, and one of them also showed rhamnose. The sugar source has a clear influence on growth and EPS synthesis, and EPS production was not enhanced by adding ethanol or increasing the nitrogen source. EPS biosynthesis starts in the exponential growth phase, and continued during the stationary growth phase. CONCLUSIONS: Higher EPS yields were obtained on cultures grown on glucose + fructose. O. oeni produces a beta-glucan, as the predominant EPS, and it is also able to produce two heteropolysaccharides. SIGNIFICANCE AND IMPACT OF THE STUDY: This work provides a better understanding of EPS synthesis by O. oeni and shows the first EPS structure described for this species.

Structural determination of a 5-O-methyl-deaminated neuraminic acid (Kdn)-containing polysaccharide isolated from Sinorhizobium fredii.

The structure of a polysaccharide from Sinorhizobium fredii SVQ293, a thiamine auxotrophic mutant of S. fredii HH103, has been determined. This polysaccharide was isolated following the protocol for lipopolysaccharide extraction. On the basis of monosaccharide analysis, methylation analysis, fast atom bombardment MS, collision-induced dissociation tandem MS, one-dimensional 1H and 13C NMR and two-dimensional NMR experiments, the structure was shown to consist of the following trisaccharide repeating unit-->2)-alpha-d-Galp-(1-->2)-beta-d-Ribf-(1-->9)-alpha-5-O-Me-++ +Kdnp- (2-->, in which Kdn stands for deaminated neuraminic acid; 25% of the Kdn residues are not methylated. The structure of this polysaccharide is novel and this is the first report of the presence of Kdn in a rhizobial polysaccharide, as well as being the first structure described containing 5-O-Me-Kdn. This Kdn-containing polysaccharide is not present in the wild-type strain HH103, which produces a 3-deoxy-d-manno-2-octulosonic acid (Kdo)-rich polysaccharide. We conclude that it is likely that the appearance of this new Kdn-containing polysaccharide is a consequence of the mutation.

Determination of the chemical structure of the capsular polysaccharide of strain B33, a fast-growing soya bean-nodulating bacterium isolated from an arid region of China.

We have determined the structure of a polysaccharide from strain B33, a fast-growing bacterium that forms nitrogen-fixing nodules with Asiatic and American soya bean cultivars. On the basis of monosaccharide analysis, methylation analysis, one-dimensional 1H- and 13C-NMR and two-dimensional NMR experiments, the structure was shown to consist of a polymer having the repeating unit -->6)-4-O-methyl-alpha-D-Glcp-(1-->4)-3-O-methyl-beta-D-GlcpA-(1--> (where GlcpA is glucopyranuronic acid and Glcp is glucopyranose). Strain B33 produces a K-antigen polysaccharide repeating unit that does not have the structural motif sugar-Kdx [where Kdx is 3-deoxy-D-manno-2-octulosonic acid (Kdo) or a Kdo-related acid] proposed for different Sinorhizobium fredii strains, all of them being effective with Asiatic soya bean cultivars but unable to form nitrogen-fixing nodules with American soya bean cultivars. Instead, it resembles the K-antigen of S. fredii strain HH303 (rhamnose, galacturonic acid)n, which is also effective with both groups of soya bean cultivars. Only the capsular polysaccharide from strains B33 and HH303 have monosaccharide components that are also present in the surface polysaccharide of Bradyrhizobium elkanii strains, which consists of a 4-O-methyl-D-glucurono-L-rhamnan.

Structural determination of a 5-acetamido-3,5,7, 9-tetradeoxy-7-(3-hydroxybutyramido)-L-glycero-L-manno-nonulos onic acid-containing homopolysaccharide isolated from Sinorhizobium fredii HH103.

The structure of a polysaccharide from Sinorhizobium fredii HH103 has been determined. This polysaccharide was isolated by following the protocol for lipopolysaccharide extraction. On the basis of monosaccharide analysis, methylation analysis, fast atom bombardment MS, matrix-assisted laser desorption ionization MS, electron-impact high-resolution MS, one-dimensional (1)H-NMR and (13)C-NMR and two-dimensional NMR experiments, the structure was shown to consist of a homopolymer of a 3:1 mixture of 5-acetamido-3,5,7, 9-tetradeoxy-7-[(R)- and (S)-3-hydroxybutyramido]-l-glycero-l-manno-nonulosonic acid. The sugar residues are attached via a glycosidic linkage to the OH group of the 3-hydroxybutyramido substituent and thus the monomers are linked via both glycosidic and amidic linkages. In contrast with the Sinorhizobium K-antigens previously reported, which are composed of a disaccharide repeating unit, the K-antigen polysacharide of S. fredii HH103 is a homopolysaccharide.