Unusual dynamic behaviour in the isotropic phase of banana mesogens detected by 2H NMR line width and T2 measurements

In this work the first experimental observation of a peculiar behavior in the isotropic phase of liquid crystals by means of H-2 NMR is reported. In particular, two five-ring banana-shaped mesogens, the 1,3-phenylenebis-{4,4'-(11-undecenyloxy)benzoyloxy}benzoate (Pbis11BB) and its 4-chloro homologue (CIPbis11BB), selectively deuterium labeled on their central rings, are the subject of our investigation. The dynamic behavior of the two liquid crystals was studied in their isotropic phases and in the nematic phase of CIPbis11BB by means of H-2 NMR line width and spin-spin relaxation time (T) analysis. The results obtained reveal that the unusual line broadening observed in the H-2 NMR spectra in the. isotropic phase, even far above the isotropic phase-mesophase transition, has a homogeneous nature. thus indicating the presence of reorientational motions much slower than in conventional isotropic liquid-crystalline phases

Macrophage HIV-1 infection in duodenal tissue of patients on long term HAART

Mucosal surfaces play a major role in human immunodeficiency virus type 1 (HIV-1) transmission and pathogenesis. Since the role of intestinal macrophages as viral reservoirs during chronic HIV-1 infection has not been elucidated, we investigated the effects of successful therapy on intestinal HIV-1 persistence. Intestinal macrophage infection was demonstrated by the expression of p24 antigen by flow cytometry and by the presence of proviral DNA, assessed by PCR. Proviral DNA was detected in duodenal mucosa of HIV-infected patients under treatment with undetectable plasma viral load. These findings confirm that intestinal macrophages can act as viral reservoirs and permit HIV-1 production even after viral suppression following antiretroviral therapy. © 2010 Elsevier B.V.Fil: Zalar, Alberto. Gobierno de la Ciudad de Buenos Aires. Hospital General de Agudos "Juan A. Fernández"; ArgentinaFil: Figueroa, Maria Ines. Gobierno de la Ciudad de Buenos Aires. Hospital General de Agudos "Juan A. Fernández"; ArgentinaFil: Ruibal Ares, Beatriz. Academia Nacional de Medicina de Buenos Aires; ArgentinaFil: Baré, Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Academia Nacional de Medicina de Buenos Aires; ArgentinaFil: Cahn, Pedro. Gobierno de la Ciudad de Buenos Aires. Hospital General de Agudos "Juan A. Fernández"; ArgentinaFil: de Bracco, Maria Marta de E.. Academia Nacional de Medicina de Buenos Aires; ArgentinaFil: Belmonte de Zalar, Liliana Elizabeth. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Academia Nacional de Medicina de Buenos Aires; Argentin

Dynamics of a Ferroelectric Liquid Crystal by means of 2H NMR Spectroscopy: A Multifrequency Relaxation Study

Spinning and tumbling motions in liquid crystals: Measurements of deuterium quadrupolar (T1Q) and spin-lattice (T1Z) relaxation times of selectively deuterated ferroelectric liquid crystals can be suitably analysed in terms of dynamic models to get detailed information on collective, overall (molecular spinning and tumbling) and internal motions (see picture). The availability of relaxation times measured at three Larmor frequencies and for two different molecular sites results in a remarkably improved reliability in the determination of the diffusion coefficients

New composites based on liquid crystalline elastomers and electroactive nanomaterials

The insertion of inorganic nanoparticles and nanowires in a liquid crystalline elastomeric environment is here investigated. The combination of ferroelectric and conductive properties of the nanomaterials with the thermo-mechanical and shape memory response of liquid single crystal elastomers based on polysiloxane is indeed very promising for new technological applications, such as electroactive actuators. In this work the preparation and physical-chemical properties of new composites are presented and discussed in comparison with those of standard liquid single crystal elastomers (LSCEs). In particular, we are reporting the preliminary results of new composites including either lead titanate nanoparticles or molibdene oxide nanowires, having different electric and conductive properties

Pyloric distensibility measurement predicts symptomatic response to intrapyloric botulinum toxin injection

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Banana-shaped molecules peculiarly oriented in a magnetic field: 2H NMR spectroscopy and Quantum Mechanical calculations

The orientational properties of the banana-shaped liquid crystal 4-chloro- 1,3-phenylenebis{4-[4'-(10-undecenyloxy)]benzoyloxy} benzoote (CIPbis11BB) are reported in the nematic phase under the effect of an external magnetic field. A new hypothesis, which states that the central ring of the aromatic core is oriented perpendicularly to the external magnetic field, is proposed. In support of this hypothesis, a series of studies based on H-2 NMR spectroscopy, both in the bulk and in solution, are discussed. H-2 NMR measurements on three selectively deuterium-labelled isotopomers are presented, together with DFT results from B3LYP/cc-pvDz calculations performed on the aromatic core. The rather flat shape of the investigated intramolecular energy surface allows for several different conformations to be populated, the computed magnetic susceptibilities of which are consistent with the proposed hypothesis of peculiar orientation of banana-shaped molecules. Moreover, the orientation of the magnetic susceptibility tensor is shown to be strongly dependent on the internal conformation of the banana-shaped molecules

Pyloric distensibility measurement after gastric surgery: Which surgeries are associated with pylorospasm?

Free AccessInternational audienceBackground and study aimsHistory of gastric surgery is found in 10% of patients with gastroparesis, and vagal lesion is often suspected to be the cause of pylorospasm. Recently, pyloric distensibility measurement using the EndoFLIP® system showed that pylorospasm was present in 30%‐50% of gastroparetic patients. Our objective was to assess whether pylorospasm, diagnosed using EndoFLIP® system was observed in three different types of gastric surgeries: antireflux surgery, sleeve gastrectomy, and esophagectomy.Patients and MethodsPyloric distensibility and pressure were measured using the EndoFLIP® system in 43 patients from two centers (18 antireflux surgery, 16 sleeve gastrectomy, and nine esophagectomy) with dyspeptic symptoms after gastric surgery, and in 21 healthy volunteers. Altered pyloric distensibility was defined as distensibility below 10 mm2/mm Hg as previously reported.ResultsCompared to healthy volunteers (distensibility: 25.2 ± 2.4 mm2/mm Hg; pressure: 9.7 ± 4.4 mm Hg), pyloric distensibility was decreased in 61.1% of patients in the antireflux surgery group (14.5 ± 3.4 mm2/mm Hg; P < .01) and 75.0% of patients in the esophagectomy group (10.8 ± 2.1 mm2/mm Hg; P < .05), while pyloric pressure was only increased in the antireflux surgery group (18.9 ± 2.2 mm Hg; P < .01). Pyloric distensibility and pressure were similar in healthy volunteers and in sleeve gastrectomy (distensibility: 20.3 ± 3.8 mm2/mm Hg; pressure: 15.8 ± 1.6 mm Hg) groups, with decreased pyloric distensibility affecting 18.7% of sleeve gastrectomy patients.ConclusionAntireflux surgery and esophagectomy were associated with pylorospasm although pylorospasm was not found in all patients. Sleeve gastrectomy was not associated with altered pyloric distensibility nor altered pyloric pressure

Does calprotectin level identify a subgroup among patients suffering from irritable bowel syndrome? Results of a prospective study

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Stress reshapes the physiological response of halophile fungi to salinity

(1) Background: Mechanisms of cellular and molecular adaptation of fungi to salinity have been commonly drawn from halotolerant strains and few studies in basidiomycete fungi. These studies have been conducted in settings where cells are subjected to stress, either hypo- or hyperosmotic, which can be a confounding factor in describing physiological mechanisms related to salinity. (2) Methods: We have studied transcriptomic changes in Aspergillus sydowii, a halophilic species, when growing in three different salinity conditions (No NaCl, 0.5 M, and 2.0 M NaCl). (3) Results: In this fungus, major physiological modifications occur under high salinity (2.0 M NaCl) and not when cultured under optimal conditions (0.5 M NaCl), suggesting that most of the mechanisms described for halophilic growth are a consequence of saline stress response and not an adaptation to saline conditions. Cell wall modifications occur exclusively at extreme salinity, with an increase in cell wall thickness and lamellar structure, which seem to involve a decrease in chitin content and an augmented content of alfa and beta-glucans. Additionally, three hydrophobin genes were differentially expressed under hypo- or hyperosmotic stress but not when the fungus grows optimally. Regarding compatible solutes, glycerol is the main compound accumulated in salt stress conditions, whereas trehalose is accumulated in the absence of salt. (4) Conclusions: Physiological responses to salinity vary greatly between optimal and high salt concentrations and are not a simple graded effect as the salt concentration increases. Our results highlight the influence of stress in reshaping the response of extremophiles to environmental challenges