Design and Testing of a New Diatom-Based Index for Heavy Metal Pollution.

The Tinto and Odiel river basins (SW Spain) are known worldwide for their unique water characteristics. Such uniqueness is a consequence of their flow through the Iberian Pyrite Belt (an area rich in metal sulphides) and the mining activities in the basins. A process of sulphide oxidation occurs in this region, which acidifies the water and increases the amount of heavy metals in it. As a result, the rivers suffer the so-called "acid mine drainage" (AMD). Traditional biotic diatom-based indexes (IPS, IBD, EPI-D, etc.) do not take into account the pollution caused by AMD. The purpose of this paper is to develop a new diatom-based index which can serve as a useful and quick monitoring tool. Such tool must reflect the level of AMD while being user friendly. We present the development and validation of the ICM (Índice de Contaminación por Metales or Metal Pollution Index). ICM demonstrated to meet successfully the above criteria and, therefore, can assess water quality in the Tinto and Odiel Rivers. In addition, ICM was applied with satisfactory results in the Guadiamar River (SW Spain), which was subjected to AMD too. Thus, we propose to make use of it in any other basin with the same type of pollution.

Oral Immunotherapy for Food Allergy: A Spanish Guideline. Immunotherapy Egg and Milk Spanish Guide (ITEMS Guide). Part I: Cow Milk and Egg Oral Immunotherapy: Introduction, Methodology, Rationale, Current State, Indications, Contraindications, and Oral Immunotherapy Build-up Phase.

BACKGROUND AND OBJECTIVE: Cow milk and egg are the most frequent causes of food allergy in the first years of life. Oral immunotherapy (OIT) has been investigated as an alternative to avoidance diets. No clinical practice guidelines on the management of OIT with milk and egg are currently available. Objectives: To develop clinical guidelines for OIT based on available scientific evidence and the opinions of experts. METHODS: A review was made of studies published between 1984 and June 2016, doctoral theses published in Spain, summaries of communications at scientific meetings (SEAIC, SEICAP, EAACI, and AAAAI), and the consensus of opinion established by a group of experts from the scientific societies SEICAP and SEAIC. RESULTS: Recommendations were established regarding the indications, requirements and practical aspects of the different phases of OIT, as well as special protocols for patients at high risk of adverse reactions. CONCLUSIONS: Clinical practice guidelines based on the consensus reached between Spanish experts are presented for the management of OIT with milk and egg.

Oral Immunotherapy for Food Allergy: A Spanish Guideline. Egg and Milk Immunotherapy Spanish Guide (ITEMS GUIDE). Part II: Maintenance Phase of Cow Milk (CM) and Egg Oral Immunotherapy (OIT), Special Treatment Dosing Schedules. Models of Dosing Schedules of OIT With CM and Egg.

BACKGROUND AND OBJECTIVE: Cow milk and egg are the most frequent causes of food allergy in the first years of life. Oral immunotherapy (OIT) has been investigated as an alternative to avoidance diets. No clinical practice guidelines on the management of OIT with milk and egg are currently available. Objectives: To develop clinical guidelines for OIT based on available scientific evidence and the opinions of experts. METHODS: A review was made of studies published between 1984 and June 2016, doctoral theses published in Spain, summaries of communications at scientific meetings (SEAIC, SEICAP, EAACI, and AAAAI), and the consensus of opinion established by a group of experts from the scientific societies SEICAP and SEAIC. RESULTS: Recommendations were established regarding the indications, requirements and practical aspects of the different phases of OIT, as well as special protocols for patients at high risk of adverse reactions. CONCLUSIONS: Clinical practice guidelines based on the consensus reached between Spanish experts are presented for the management of OIT with milk and egg.

Oral immunotherapy for food allergy: A Spanish guideline. Egg and milk immunotherapy Spanish guide (ITEMS GUIDE). Part 2: Maintenance phase of cow milk (CM) and egg oral immunotherapy (OIT), special treatment dosing schedules. Models of dosing schedules of OIT with CM and EGG.

INTRODUCTION: Cow's milk and egg are the most frequent causes of food allergy in the first years of life. Treatments such as oral immunotherapy (OIT) have been investigated as an alternative to avoidance diets. No clinical practice guides on the management of OIT with milk and egg are currently available. OBJECTIVES: To develop a clinical guide on OIT based on the available scientific evidence and the opinions of experts. METHODS: A review was made of studies published in the period between 1984 and June 2016, Doctoral Theses published in Spain, and summaries of communications at congresses (SEAIC, SEICAP, EAACI, AAAAI), with evaluation of the opinion consensus established by a group of experts pertaining to the scientific societies SEICAP and SEAIC. RESULTS: Recommendations have been established regarding the indications, requirements and practical aspects of the different phases of OIT, as well as special protocols for patients at high risk of suffering adverse reactions. CONCLUSIONS: A clinical practice guide is presented for the management of OIT with milk and egg, based on the opinion consensus of Spanish experts.

Oral immunotherapy for food allergy: A Spanish guideline. Immunotherapy egg and milk Spanish guide (items guide). Part I: Cow milk and egg oral immunotherapy: Introduction, methodology, rationale, current state, indications contraindications and oral immunotherapy build-up phase.

INTRODUCTION: Cow's milk and egg are the most frequent causes of food allergy in the first years of life. Treatments such as oral immunotherapy (OIT) have been investigated as an alternative to avoidance diets. No clinical practice guides on the management of OIT with milk and egg are currently available. OBJECTIVES: To develop a clinical guide on OIT based on the available scientific evidence and the opinions of experts. METHODS: A review was made of studies published in the period between 1984 and June 2016, Doctoral Theses published in Spain, and summaries of communications at congresses (SEAIC, SEICAP, EAACI, AAAAI), with evaluation of the opinion consensus established by a group of experts pertaining to the scientific societies SEICAP and SEAIC. RESULTS: Recommendations have been established regarding the indications, requirements and practical aspects of the different phases of OIT, as well as special protocols for patients at high risk of suffering adverse reactions. CONCLUSIONS: A clinical practice guide is presented for the management of OIT with milk and egg, based on the opinion consensus of Spanish experts.

Tolerance to COX-2 inhibitors in children with hypersensitivity to nonsteroidal anti-inflammatory drugs.

BACKGROUND: Hypersensitivity to nonsteroidal anti-inflammatory drugs (NSAIDs) can affect children, with the mechanism proposed being inhibition of the cyclooxygenase enzyme-1 (COX-1). In these patients nonchemically related NSAIDs, including COX-2 inhibitors, can induce the reaction, hampering treatment of fever and inflammatory processes. OBJECTIVES: To analyse retrospectively tolerance to etoricoxib, a selective COX-2 inhibitor, and to meloxicam, a preferential COX-2 inhibitor, in children with hypersensitivity to NSAIDs. METHODS: Clinical records of children (aged 1-14 years) diagnosed with hypersensitivity reactions to NSAIDs from January 2006 to January 2013 were included. The diagnosis was confirmed by oral drug provocation test (DPT) with the culprit NSAIDs and acetylsalicylic acid (ASA). Tolerance to paracetamol, etoricoxib and meloxicam was also evaluated. RESULTS: The study included 41 children with a positive DPT with ASA and the culprit NSAID. DPT with paracetamol and etoricoxib was negative in all children, although two (4.9%) children developed a reaction after the administration of meloxicam. CONCLUSIONS: These data indicate that both etoricoxib and meloxicam are good alternatives for treatment in older children with hypersensitivity to NSAIDs.

Are hip hemiarthroplasty and total hip arthroplasty infections different entities? The importance of hip fractures.

Hip hemiarthroplasty (HHA) and total hip arthroplasty (THA) infections are usually considered as one entity; however, they may show important differences. We analyze these differences, as well as predictors of treatment failure (TF) and poor functional status among patients with prosthetic hip infections (PHIs). A multicenter cohort study of consecutive patients with PHIs was performed. The main outcome variable was TF after the first surgical treatment performed to treat the infection. Multivariate analysis was used to identify predictors of TF. A total of 127 patients with PHI were included (43 HHA, 84 THA). Patients with HHA infections were more frequently women (88% vs. 54%; p < 0.001), had comorbidities (86% vs. 67%, p = 0.02), and were older (median age 79 vs. 65 years, p < 0.001), and the reason for arthroplasty was more frequently a fracture (100% vs. 18%, p < 0.001). Failure of initial treatment and crude mortality were more frequent among HHA patients (44% vs. 23%, p = 0.01 and 28% vs. 7%, p = 0.001, respectively). However, HHA was not associated with TF in the multivariate analysis when hip fracture was considered; thus, variables independently associated with TF were hip fracture, inadequate surgical management, prosthesis retention, and higher C-reactive protein level. Failure of the first surgical treatment was associated with poorer functional status. HHA and THA infections showed significant differences in epidemiology, clinical features, and outcome. Although patients with HHA infections had a higher risk of TF, this was related to the reason for hip implant: a hip fracture. Success of the initial management of infection is a predictor of better clinical and functional outcome.

Tolerability during double-blind randomized phase I trials with the house dust mite allergy immunotherapy tablet in adults and children.

BACKGROUND AND OBJECTIVE: The orodispersible house dust mite (HDM) sublingual immunotherapy (SLIT)-tablet (ALK, Denmark) is being developed for the treatment of HDM respiratory allergic disease. The objective of the 2 phase I trials was to investigate tolerability and the acceptable dose range of HDM SLIT-tablet treatment in adults and children with HDM respiratory allergic disease. PATIENTS AND METHODS: The trials were randomized, multiple-dose, dose-escalation, double-blind, placebo-controlled phase I trials including patients with HDM-induced asthma, with or without rhinoconjunctivitis. Both trials were registered in EudraCT (Trial 1: 2005-002151-41; Trial 2: 2007-000402-67). Trial 1 included 71 adults (18-63 years) and trial 2 included 72 children (5-14 years). Both trials included 6 dose groups that were randomized 3:1 to active treatment or placebo once daily for 28 days. Adverse events (AEs) were coded in MedDRA (version 8.1 or later). Immunological variables included specific IgE and IgE-blocking factor. RESULTS: No serious AEs were reported. In trial 1 (maximum dose, 32 development units [DU]), 1 patient in the 16 DU group discontinued due to AEs. The entire 32 DU group was discontinued as 1 patient had a severe adverse reaction. In trial 2 (maximum dose, 12 DU), no patients discontinued prematurely. The most frequently reported AEs were mild application-site related events. The total number of events was dose-related within each trial. HDM SLIT-tablet treatment induced changes in immunological parameters in a dose-dependent manner. CONCLUSIONS: These trials demonstrate that doses up to 12 DU of HDM SLIT-tablet were tolerated in the selected populations, and thus are suitable for further clinical investigations in adults and children with HDM respiratory allergic disease.

Clinical standards for the diagnosis and management of asthma in low- and middle-income countries.

BACKGROUND: The aim of these clinical standards is to aid the diagnosis and management of asthma in low-resource settings in low- and middle-income countries (LMICs).METHODS: A panel of 52 experts in the field of asthma in LMICs participated in a two-stage Delphi process to establish and reach a consensus on the clinical standards.RESULTS: Eighteen clinical standards were defined: Standard 1, Every individual with symptoms and signs compatible with asthma should undergo a clinical assessment; Standard 2, In individuals (>6 years) with a clinical assessment supportive of a diagnosis of asthma, a hand-held spirometry measurement should be used to confirm variable expiratory airflow limitation by demonstrating an acute response to a bronchodilator; Standard 3, Pre- and post-bronchodilator spirometry should be performed in individuals (>6 years) to support diagnosis before treatment is commenced if there is diagnostic uncertainty; Standard 4, Individuals with an acute exacerbation of asthma and clinical signs of hypoxaemia or increased work of breathing should be given supplementary oxygen to maintain saturation at 94-98%; Standard 5, Inhaled short-acting beta-2 agonists (SABAs) should be used as an emergency reliever in individuals with asthma via an appropriate spacer device for metered-dose inhalers; Standard 6, Short-course oral corticosteroids should be administered in appropriate doses to individuals having moderate to severe acute asthma exacerbations (minimum 3-5 days); Standard 7, Individuals having a severe asthma exacerbation should receive emergency care, including oxygen therapy, systemic corticosteroids, inhaled bronchodilators (e.g., salbutamol with or without ipratropium bromide) and a single dose of intravenous magnesium sulphate should be considered; Standard 8, All individuals with asthma should receive education about asthma and a personalised action plan; Standard 9, Inhaled medications (excluding dry-powder devices) should be administered via an appropriate spacer device in both adults and children. Children aged 0-3 years will require the spacer to be coupled to a face mask; Standard 10, Children aged <5 years with asthma should receive a SABA as-needed at step 1 and an inhaled corticosteroid (ICS) to cover periods of wheezing due to respiratory viral infections, and SABA as-needed and daily ICS from step 2 upwards; Standard 11, Children aged 6-11 years with asthma should receive an ICS taken whenever an inhaled SABA is used; Standard 12, All adolescents aged 12-18 years and adults with asthma should receive a combination inhaler (ICS and rapid onset of action long-acting beta-agonist [LABA] such as budesonide-formoterol), where available, to be used either as-needed (for mild asthma) or as both maintenance and reliever therapy, for moderate to severe asthma; Standard 13, Inhaled SABA alone for the management of patients aged >12 years is not recommended as it is associated with increased risk of morbidity and mortality. It should only be used where there is no access to ICS.The following standards (14-18) are for settings where there is no access to inhaled medicines. Standard 14, Patients without access to corticosteroids should be provided with a single short course of emergency oral prednisolone; Standard 15, Oral SABA for symptomatic relief should be used only if no inhaled SABA is available. Adjust to the individual's lowest beneficial dose to minimise adverse effects; Standard 16, Oral leukotriene receptor antagonists (LTRA) can be used as a preventive medication and is preferable to the use of long-term oral systemic corticosteroids; Standard 17, In exceptional circumstances, when there is a high risk of mortality from exacerbations, low-dose oral prednisolone daily or on alternate days may be considered on a case-by-case basis; Standard 18. Oral theophylline should be restricted for use in situations where it is the only bronchodilator treatment option available.CONCLUSION: These first consensus-based clinical standards for asthma management in LMICs are intended to help clinicians provide the most effective care for people in resource-limited settings.

Endoscopic management of brainstem injury due to ventriculoperitoneal shunt placement.

INTRODUCTION: We report a patient who suffered from brainstem injury following ventriculoperitoneal (VP) shunt placement in the fourth ventricle. DISCUSSION: A 20-year-old man with complex hydrocephalus and trapped fourth ventricle underwent a suboccipital placement of a VP shunt. Postprocedure patient developed double vision. Magnetic resonance imaging showed that the catheter was penetrating the dorsal brainstem at the level of the pontomedullary junction. Patient was referred to our Neuroendoscopic Clinic. Physical exam demonstrated pure right VI cranial nerve palsy. Patient underwent flexible endoscopic exploration of the ventricular system. Some of the endoscopic findings were severe aqueductal stenosis and brainstem injury from the catheter. Aqueductoplasty, transaqueductal approach into the fourth ventricle, and endoscopic repositioning of the catheter were some of the procedures performed. Patient recovered full neurological function. The combination of endoscopic exploration and shunt is a good alternative for patients with complex hydrocephalus. A transaqueductal approach to the fourth ventricle with flexible scope is an alternative for fourth ventricle pathology.

Decrease of premature mothers' stress levels in the intensive care unit. / Disminución del nivel de estrés en madres de prematuros en la unidad de cuidados intensivos.

OBJECTIVE: To determine the effectiveness of the 'Creating Opportunities for Parent Empowerment' (COPE) programme in reducing stress levels in mothers of preterm infants in the neonatal intensive care unit (NICU). METHODS: Clinical trial performed in Colombia, including mothers of infants younger than 34 weeks of gestation, hospitalized, without a history of premature delivery. The mothers with psychiatric illnesses, language disorders, history of use of psychoactive substances and whose newborns had a congenital malformation were excluded. A group intervened with the COPE programme and a control group with the usual institutional management were formed. Block randomization and masking was used for mothers and evaluators. The Parental Stress Scale was applied: NICU; Shapiro Wilk normality test, Wilcoxon test and covariance analysis (ANCOVA) with a significance level of p<.05, 95% CI. RESULTS: 66 mothers were enrolled. The two groups were similar in their demographic characteristics and in the initial stress level score. The control group increased the final stress score in two categories and the intervention group decreased final values in all categories. The initial and final scores of the overall general stress level showed a significant decrease (p<.01), but when comparing with the ANCOVA analysis there was no significant difference (p=.4). CONCLUSIONS: The COPE programme reduces the level of maternal stress, strengthening aspects during hospitalization, such as: emotional support, strengthening their role as caregivers and interaction with their babies and the development of a friendly environment in the NICU.

[Statins and brain protection mechanisms]. / Estatinas y mecanismos de proteccion cerebral.

INTRODUCTION: The 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA) inhibitors or statins are drugs used in the treatment of dyslipidemies. The clinical trials performed for evaluation of the efficacy observed a reduced incidence of stroke and other trials have demonstrated a better outcome after stroke and subrachnoid hemorrhage. DEVELOPMENT: In the last years, new actions of statins have been described (pleiotropics). The statins seem to originate neuroprotector effects, such as up-regulation of endothelial nitric oxide synthase; creation of a fibrinolytic profile with suppression of the intravascular stability of the clot; immunomodulation by regulation of cytokines and cellular adhesion molecules; anti-oxidation by reduction of lipidic peroxidation; induction of neuroplasticity by increment of neurotrophic factors and protection of neuroexcitotoxicity, maybe by regulation of intracellular calcium or depletion of intracellular sterols. All these actions can be explained by decreament of isoprenoids synthesis. CONCLUSION: The pleiotropic properties of the statins offer the possibility to consider them as possible neuroprotectors, which should be evaluated in pathologies where the molecular ways interfered are involved, for example head injury and stroke.

[Consensus-based approach for severe paediatric asthma in routine clinical practice]. / Consenso para el abordaje del asma grave pediátrica en la práctica clínica habitual.

INTRODUCTION: Accurate identification of paediatric patients with severe asthma is essential for an adequate management of the disease. However, criteria for defining severe asthma and recommendations for control vary among different guidelines. MATERIAL AND METHODS: An online survey was conducted to explore expert opinions about the definition and management of severe paediatric asthma. To reach a consensus agreement, a modified Delphi technique was used, and practice guidelines were prepared after the analysis of the results. RESULTS: Eleven paediatric chest disease physicians and allergy specialists with wide expertise in severe asthma responded to the survey. Consensus was reached in 50 out of 65 questions (76.92%). It was considered that a patient has severe asthma if during the previous year they have required 2 or more cycles of oral steroids, required daily treatment with medium doses of inhaled corticosteroids (with other controller medication) or high doses (with or without other controller medication), did not respond to optimised conventional treatment, or if the disease threatened the life of the patient or seriously impairs their quality of life. The definition of severe asthma may also include patients who justifiably use health resources on a regular basis, or have psychosocial or environmental factors impeding control. For monitoring, the use of questionnaires designed specifically for paediatric population, such as CAN or ACT, is recommended. As regards treatment, the use of omalizumab should be considered prior to the use of oral corticosteroids. CONCLUSIONS: This paper provides consensus recommendations that may be useful in the management of severe paediatric asthma.

Characterization of an aromatic amino acid aminotransferase from Rhizobium leguminosarum biovar trifolii.

The most abundant aromatic amino acid aminotransferase of Rhizobium leguminosarum biovar trifolii was partially purified. The molecular mass of the enzyme was estimated to be 53 kDa by gel filtration. The enzyme transaminated aromatic amino acids and histidine. It used aromatic keto acids and alpha-ketoglutaric and oxalacetic acids as amino-group acceptors. The optimum temperature was 35 degrees C. Using phenylalanine and alpha-ketoglutaric acid as substrates the activation energy was 46.2 kJ.mol-1 and for the couple tryptophan:alpha-ketoglutaric acid it was 70.3 kJ.mol-1. The optimum pH was different for each substrate: 7.3 for phenylalanine, 7.9 for histidine and 8.7 for tryptophan.

High frequency of serious side effects from meglumine antimoniate given without an upper limit dose for the treatment of visceral leishmaniasis in human immunodeficiency virus type-1-infected patients.

Organic pentavalent antimonials are one of the mainstays of treatment for visceral leishmaniasis (VL). Few data are available on the toxicity and efficacy of these drugs at the dosing schedule recommended by the Centers for Disease Control and Prevention (CDC) (Atlanta, GA). We analyzed 25 VL episodes in human immunodeficiency virus (HIV)-infected patients who were treated with meglumine antimoniate (MA) at the CDC-recommended dose in southern Spain. Adverse effects were observed in 14 (56%) VL episodes. In 7 (28%), treatment with MA was permanently discontinued due to serious adverse effects that included acute pancreatitis, acute renal failure, and leukopenia. Three (12%) patients died during therapy due to severe acute pancreatitis attributable to MA. The dosing regimen of MA currently recommended for treating VL is associated with a high rate of serious side effects in HIV-1-infected patients.

Relationship between low bone mineral density and highly active antiretroviral therapy including protease inhibitors in HIV-infected patients.

PURPOSE: The objectives of this study were to determine the prevalence of osteopenia and the factors associated with its presence in HIV-infected patients under highly active antiretroviral therapy (HAART) and to assess the changes of bone mineral density (BMD) in a population followed prospectively. METHOD: BMD was assessed by dual-energy X-ray absorptiometry (DEXA) scans at the lumbar spine and at the femoral neck in 78 HIV-infected patients who had previously received HAART as the first antiretroviral regimen and in 11 antiretroviral-naive HIV-infected patients. BMD measurements were repeated in 70 treated patients who had completed 1 year of follow-up. RESULTS: Thirty-seven (42%) patients showed osteopenia at any localization. The prevalence of osteopenia in PI-naive patients was 23% versus 49% in individuals who had received PI at any moment [p =.001; adjusted odds ratio (95% CI) = 0.11 (0.02-0.48)]. The frequency of osteopenia was significantly higher among men than among women [50% vs. 17%; p =.016; adjusted OR (95% CI) = 12.1 (2.22-66.20)]. The level of plasma albumin was independently associated with osteopenia [adjusted OR (95% CI) per each g/dL of plasma albumin decrease 2.55 (1.18-10)]. In patients in whom a second DEXA was done, no significant changes in BMD were found. CONCLUSION: The prevalence of osteopenia in HIV-infected patients on HAART is high. Loss of BMD is associated with PI therapy, low plasma albumin level, and male sex. Osteopenia does not progress after 1 year of continued HAART.

Transient energy coupling between rhizobia and legume cells mediated by the peribacteroid membrane ATPase proton pump.

We present a model for the metabolic coupling between rhizobia and plant cell in the nitrogen-fixing legume root nodules. The symbiosome, an organelle-like structure formed by the modified rhizobia (the bacteroids) enclosed by a plant cell derived peribacteroid membrane, is an unique structure in which two energized membranes are closely packed: the inner bacteroid membrane and the peribacteroid membrane that possesses an ATPase proton pump. The model is based on the following points: (i) The permeability for hydrogen ions of the outer membrane of the rhizobia. (ii) The reversibility of the ATPase proton pump of the peribacteroid membrane [Szafran, M.M. and Haaker, H. (1995) Plant Physiol. 108, 1227-1232]. (iii) The relative affinites for oxygen of the bacteroid and plant mitochondria terminal oxidases, and the prevailing oxygen concentration inside the nodule, which results in aerobic metabolism for the bacteroid, but in quite fermentative catabolism for the host plant cell. We propose that the bacteroid can transiently supply free energy to the plant cell in the form of protonmotive force by the movement of hydrogen ions from the bacteroid periplasmic space to the plant cytoplasm through the peribacteroid membrane ATPase. The proposed hydrogen ion flux could be dependent on the phosphorylation potential in both the plant cell cytoplasm and the bacteroid, and the simultaneous ion movements to avoid the development of opposite delta psi. It could be important in situations of transient ATP depletion inside plant cell, which involves the block of ammonia assimilation and, subsequently, the inhibition of bacteroid nitrogenase.

Studies on the structure and the solution conformation of an acidic extracellular polysaccharide isolated from Bradyrhizobium.

The structure of an acidic extracellular polysaccharide isolated from Bradyrhizobium (Chamaecytisus proliferus) has been elucidated by hydrolysis, methylation analysis, and 1D and 2D 1H- and 13C-NMR spectroscopy of the complete polysaccharide. The NMR spectrum showed that microheterogeneity was present due to the minor existence of a variety of O-acetyl groups. Thus, a deacetylated sample was prepared by alkaline treatment which was then fully analysed. The deacetylated polysaccharide has the following sequence: -->3)-[alpha-D-Galp-(1-->6)-alpha-D-Glcp-(1-->3)-beta-D-Glcp-(1-->3)- alpha-D-GalpA-(1-->3)-alpha-D-Manp-(1--> The sample is partially O-methylated at position 4 of the alpha-D-Galp-(1-->6) unit. In addition, the same moiety of the native sample is also partially and heterogeneously O-acetylated. The conformational features of the deacetylated sample have been evaluated by molecular mechanics and dynamics calculations and NOE spectroscopy. The results indicate that the polysaccharide may adopt a variety of three dimensional shapes, and that there is a fair agreement between the NMR-derived distances and those provided by the calculations

Solution conformation and dynamics of an extracellular polysaccharide isolated from Bradyrhyzobium as deduced from 1H-NMR off resonance ROESY and 13C-NMR relaxation measurements.

The conformational and dynamical features of an extracellular branched deacetylated polysaccharide isolated from Bradyrhizobium (Chamaecytisus proliferus) have been investigated by homo and heteronuclear NMR methods. 1H-NMR cross relaxation rates have been obtained for this polysaccharide through regular NOESY and ROESY spectra as well as by modern off resonance ROESY techniques. Local proton-proton correlation times as well as interproton distances have been obtained. 13C-NMR relaxation parameters (T1, T2, NOE) have also been measured at two different magnetic fields and interpreted using different approximations based on the Lipari and Szabo model free approach. The analysis of the data indicates the existence of important flexibility for the different linkages of the polysaccharide. Motions in the range of several ns contribute to the relaxation of the macromolecule, although faster internal motions in the 600-800 ps time scales are also present. These time scales indicate that segmental motions as well as internal motions around the glycosidic linkages are the major sources of relaxation for this molecule at 299 K.