Exopolysaccharide is detrimental for the symbiotic performance of Sinorhizobium fredii HH103 mutants with a truncated lipopolysaccharide core.

The nitrogen-fixing rhizobia-legume symbiosis relies on a complex interchange of molecular signals between the two partners during the whole interaction. On the bacterial side, different surface polysaccharides, such as lipopolysaccharide (LPS) and exopolysaccharide (EPS), might play important roles for the success of the interaction. In a previous work we studied two Sinorhizobium fredii HH103 mutants affected in the rkpK and lpsL genes, which are responsible for the production of glucuronic acid and galacturonic acid, respectively. Both mutants produced an altered LPS, and the rkpK mutant, in addition, lacked EPS. These mutants were differently affected in symbiosis with Glycine max and Vigna unguiculata, with the lpsL mutant showing a stronger impairment than the rkpK mutant. In the present work we have further investigated the LPS structure and the symbiotic abilities of the HH103 lpsL and rkpK mutants. We demonstrate that both strains produce the same LPS, with a truncated core oligosaccharide devoid of uronic acids. We show that the symbiotic performance of the lpsL mutant with Macroptilium atropurpureum and Glycyrrhiza uralensis is worse than that of the rkpK mutant. Introduction of an exoA mutation (which avoids EPS production) in HH103 lpsL improved its symbiotic performance with G. max, M. atropurpureum, and G. uralensis to the level exhibited by HH103 rkpK, suggesting that the presence of EPS might hide the truncated LPS produced by the former mutant.

Increasing outer membrane complexity: the case of the lipopolysaccharide lipid A from marine Cellulophaga pacifica.

Gram-negative bacteria living in marine waters have evolved peculiar adaptation strategies to deal with the numerous stress conditions that characterize aquatic environments. Among the multiple mechanisms for efficient adaptation, these bacteria typically exhibit chemical modifications in the structure of the lipopolysaccharide (LPS), which is a fundamental component of their outer membrane. In particular, the glycolipid anchor to the membrane of marine bacteria LPSs, i.e. the lipid A, frequently shows unusual chemical structures, which are reflected in equally singular immunological properties with potential applications as immune adjuvants or anti-sepsis drugs. In this work, we determined the chemical structure of the lipid A from Cellulophaga pacifica KMM 3664T isolated from the Sea of Japan. This bacterium showed to produce a heterogeneous mixture of lipid A molecules that mainly display five acyl chains and carry a single phosphate and a D-mannose disaccharide on the glucosamine backbone. Furthermore, we proved that C. pacifica KMM 3664T LPS acts as a weaker activator of Toll-like receptor 4 (TLR4) compared to the prototypical enterobacterial Salmonella typhimurium LPS. Our results are relevant to the future development of novel vaccine adjuvants and immunomodulators inspired by marine LPS chemistry.

Bucking the trend: understanding lipopolysaccharide structure and outer membrane dynamics in cold-adapted Pseudomonas isolated from Enigma Lake, Antarctica.

Cold environments are predominant over the Earth and are inhabited by bacteria able to cope with a series of simultaneous environmental pressures. Gram-negative species of the Pseudomonas genus are the predominant ones isolated from cold habitats, making them an excellent model for studying the mechanisms of bacterial adaptation to the most extreme habitats on our planet. Here we focused on the lipopolysaccharide (LPS) structure and the outer membrane dynamics of Pseudomonas sp. EW#7, a strain isolated from Enigma Lake in Antarctica where, among other extreme characteristics, water temperature can reach 0.4 °C. We show that near-zero growth temperature mostly affects the LPS lipid A component. An uncommon tendency of decreasing lipid A secondary hydroxylation while increasing its phosphorylation degree was observed. This resulted in a faster lateral diffusion of lipid chains in the membrane and therefore in an enhancement of its fluctuations that guarantee membrane integrity and flexibility.

Early myocardial deformation changes in hypercholesterolemic and obese children and adolescents: a 2D and 3D speckle tracking echocardiography study.

Dyslipidemia and obesity are considered strong risk factors for premature atherosclerotic cardiovascular disease and increased morbidity and mortality and may have a negative impact on myocardial function.Our purpose was to assess the presence of early myocardial deformation abnormalities in dyslipidemic children free from other cardiovascular risk factors, using 2-dimensional speckle tracking echocardiography (2DSTE) and 3-dimensional speckle tracking echocardiography (3DSTE).We studied 80 consecutive nonselected patients (6-18 years of age) with hypercholesterolemia (low-density lipoprotein [LDL] cholesterol levels >95th percentile for age and sex). Forty of them had normal weight and 40 were obese (body mass index >95th percentile for age and sex). Forty healthy age-matched children were selected as controls. Left ventricular (LV) global longitudinal, circumferential, and radial strains were calculated by 2DSTE and 3DSTE. Global area strain (GAS) was calculated by 3DSTE as percentage of variation in surface area defined by the longitudinal and circumferential strain vectors. Right ventricular (RV) global and free-wall longitudinal strain and LV and RV diastolic strain rate parameters were obtained. Data analysis was performed offline.LV global longitudinal strain and GAS were lower in normal-weight and obese dyslipidemic children compared with normal controls and reduced in obese patients compared with normal-weight dyslipidemic children. LV early diastolic strain rate was lower compared with normals. RV global and free-wall longitudinal strain was significantly reduced in obese patients when compared with the control group. A significant inverse correlation was found between LV strain, LDL cholesterol levels, and body mass index.2DSTE and 3DSTE show LV longitudinal strain and GAS changes in dyslipidemic children and adolescents free from other cardiovascular risk factors or structural cardiac abnormalities. Obesity causes an additive adverse effect on LV strain parameters and RV strain impairment.

Nutritional care in a nursing home in Italy.

INTRODUCTION: Malnutrition is a clinical condition due to the imbalance among needs, intake and use of nutrients, leading to the increase of morbidity and mortality, and to the impairment of quality of life. Even in industrialized countries undernutrition is becoming an alarming phenomenon, especially involving elderly institutionalized subjects. A multicentric study called PIMAI (Project Iatrogenic MAlnutrition in Italy), was carried out in Italy over 2005. The aims of this study were to determine the prevalence of malnutrition in hospitals and in nursing care homes (NH), to assess the level of nutritional attention and to measure the perceived quality in food and nutritional care. This paper represents a preliminary analysis of data collected in a NH included in the PIMAI project. MATERIALS AND METHODS: A total of 100 subjects (29 males and 71 females, aged 80.2±10 years), were recruited from January to June 2005 at the Clinical Rehabilitation Institute "Villa delle Querce" in Nemi (Rome), among patients in the NH facility. All the participants underwent a multidimensional geriatric evaluation (considering nutritional, clinical, functional and cognitive parameters), and a survey on "perceived quality" of nutritional care. RESULTS AND DISCUSSION: According to nutritional status defined by the Mini Nutritional Assessment®, data analysis showed a high prevalence of malnutrition (36%) especially related to advanced age, chewing, cognitive and functional impairments. Patients seemed to consider nutrition to be important for their health; on the other hand, they were not thoroughly satisfied with the quality of food. Particularly, it was observed scarce attention to nutritional status from medical and nursing staff. CONCLUSIONS: Our study confirms the need to pay greater attention to nutritional status in elderly institutionalized subjects. Medical and nursing teams need to be aware of the importance to perform an evaluation of nutritional status in these subset of subjects.

Comprehensive assessment of biventricular function and aortic stiffness in athletes with different forms of training by three-dimensional echocardiography and strain imaging.

AIMS: Previous studies have shown distinct models of cardiac adaptations to the training in master athletes and different effects of endurance and strength-training on cardiovascular function. We attempted to assess left-ventricular (LV) function, aortic (Ao) function, and right-ventricular (RV) function in athletes with different forms of training by using three-dimensional (3D) echocardiography, tissue Doppler imaging (TDI) and speckle-tracking imaging (STI). METHODS AND RESULTS: We examined 35 male marathon runners (endurance-trained athletes, ETA), 35 powerlifting athletes (strength-trained athletes, STA), 35 martial arts athletes (mixed-trained athletes, MTA), and 35 sedentary untrained healthy men (controls, CTR). Two-dimensional and three-dimensional echocardiography were performed for the assessment of LV and RV systolic/diastolic function. LV and RV longitudinal strain (LS) and LV torsion (LVtor) were determined using STI (EchoPAC BT11, GE-Ultrasound). Maximum velocity of systolic wall expansion peaks (AoSvel) was determined using TDI. ETA experienced LV eccentric hypertrophy with increased 3D LV end-diastolic volume and mass and significant increase in peak systolic apical rotation and LVtor. In all groups of athletes, RV-LS was reduced at rest and improved after exercise. AoSvel was significantly increased in ETA and MTA and significantly decreased in STA compared with CTR. There were good correlations between LV remodelling and aortic stiffness values. Multivariate analysis showed aortic wall velocities to be independently related to LV mass index. CONCLUSION: In strength-trained, endurance-trained, and mixed-trained athletes, ventricular and vascular response assessed by 3DE, TDI, and STI underlies different adaptations of LV, RV, and aortic indexes.

Left ventricular torsion abnormalities in patients with obstructive sleep apnea syndrome: an early sign of subclinical dysfunction.

BACKGROUND: Previous echocardiographic studies using tissue Doppler imaging (TDI) and speckle tracking imaging (STI) have demonstrated that obstructive sleep apnea syndrome (OSAS) patients may develop subclinical left ventricular (LV) systolic and diastolic dysfunction. Our purpose was to evaluate the impact of OSAS on LV torsion dynamics and aortic stiffness by using TDI and STI echocardiography. METHODS: Forty-two patients with OSAS and no comorbidities were studied. They were classified into mild and severe OSAS according to the apnea-hypopnea index (AHI). Thirty-five healthy subjects were selected as controls. Fifteen patients with severe OSAS underwent chronic nocturnal nasal continuous positive airway pressure (CPAP) therapy. Standard echocardiographic parameters were assessed. Global LV longitudinal strain (LS), radial and circumferential strain were determined by STI. Averaged LV rotation and rotational velocities from the base and apex were obtained and used for calculation of LV torsion (LVtor). Mitral annular velocities and aortic wall velocities and strain (AoS) were also obtained by TDI. RESULTS: Severe OSAS had decreased LS compared with control subjects. LVtor increased significantly in severe OSAS compared to normals (p<.001) as a result of a predominant increase in apical rotation and was independently related to AHI and AoS in a multiple stepwise linear regression model. The group treated with CPAP had a significant decrease in LVtor and aortic stiffness index and significant increase in LS and AoS. CONCLUSIONS: LVtor, LS and AoS were identified as parameters demonstrating an association between LV dysfunction, aortic stiffness and severity of OSAS independently of other possible factors or comorbidities.

Assessment of right ventricular function by three-dimensional echocardiography and myocardial strain imaging in adult atrial septal defect before and after percutaneous closure.

Real-time three-dimensional (3D) echocardiography allows us to measure right ventricular (RV) end-diastolic volume irrespective of its shape. Tissue Doppler imaging (TDI) and speckle tracking imaging (STI) are new tools to assess myocardial function. We sought to evaluate RV function by 3D echocardiography and myocardial strain imaging in adult patients with atrial septal defect (ASD) before and 6 months after transcatheter closure in order to assess the utility of these new indexes in comparison with standard two-dimensional (2D) and Doppler parameters. Thirty-nine ASD patients and 39 healthy age- and sex-matched controls were studied using a commercially available cardiovascular ultrasound system. 2D-Doppler parameters of RV function (fractional area change, tricuspid annular plane systolic excursion, myocardial performance index) were calculated. 3D RV volumes were also obtained. RV peak-systolic velocities, peak-systolic strain, and peak systolic and diastolic strain-rate were measured in the basal, mid and apical segments of lateral and septal walls in apical 4-chamber view by TDI and STI. In open ASD, RV ejection fraction (3D-RVEF) and global and regional RV longitudinal strain were significantly higher than control group and decreased significantly after closure. By multivariate analysis 3D-RVEF, apical strain and strain rate were independent predictors of functional class. ROC analysis showed 3D-RVEF and apical strain to be more sensitive predictors of unfavorable outcome after defect closure compared to 2D-Doppler indexes. 3D echocardiography and myocardial strain imaging give useful insights in the quantitative assessment of RV function in ASD patients before and after closure.