Functions of cell surface galectin-glycoprotein lattices

Programmed remodeling of cell surface glycans by the sequential action of specific glycosyltransferases can control biological processes by generating or masking ligands for endogenous lectins. Galectins, a family of animal lectins with affinity for beta-galactosides, can form multivalent complexes with cell surface glycoconjugates and deliver a variety of intracellular signals to modulate cell activation, differentiation, and survival. Recent efforts involving genetic or biochemical manipulation of O-glycosylation and N-glycosylation pathways, as well as blockade of the synthesis of endogenous galectins, have illuminated essential roles for galectin-glycoprotein lattices in the control of biological processes including receptor turnover and endocytosis, host-pathogen interactions, and immune cell activation and homeostasis.Fil: Rabinovich, Gabriel Adrián. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Toscano, Marta Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Jackson, Shawn S.. University of Maryland; Estados UnidosFil: Vasta, Gerardo R.. University of Maryland; Estados Unido

SiO collimated outflows driven by high-mass YSOs in G24.78+0.08

We imaged the molecular outflows towards the cluster of high-mass young stellar objects G24.78+0.08 at high-angular resolution using SiO emission, which is considered the classical tracer of protostellar jets. We performed SiO observations with the VLA interferometer in the J = 1-0 v=0 transition and with the SMA array in the 5-4 transition. A complementary IRAM 30-m single-dish survey in the (2-1), (3-2), (5-4), and (6-5) SiO lines was also carried out. Two collimated SiO high-velocity outflows driven by the A2 and C millimeter continuum massive cores have been imaged. On the other hand, we detected no SiO outflow driven by the young stellar objects in more evolved evolutionary phases that are associated with ultracompact (B) or hypercompact (A1) HII regions. The LVG analysis reveals high-density gas (10^3-10^4 cm-3), with well constrained SiO column densities (0.5-1 10^15 cm-2). The driving source of the A2 outflow is associated with typical hot core tracers such as methyl formate, vinyl cyanide, cyanoacetilene, and acetone. The driving source of the main SiO outflow in G24 has an estimated luminosity of a few 10^4 Lsun (typical of a late O-type star) and is embedded in the 1.3 mm continuum core A2, which in turn is located at the centre of a hot core that rotates on a plane perpendicular to the outflow main axis. The present SiO images support a scenario similar to the low-mass case for massive star formation, where jets that are clearly traced by SiO emission, create outflows of swept-up ambient gas usually traced by CO.Comment: Astronomy & Astrophysics, in pres

Duodenal intraepithelial lymphocytes of children with cow milk allergy preferentially bind the glycan-binding protein galectin-3

A breakdown in intestinal homeostasis results in inflammatory bowel diseases including coeliac disease and allergy. Galectins, evolutionarily conserved beta-galactoside-binding proteins, can modulate immune-epithelial cell interactions by influencing immune cell fate and cytokine secretion. In this study we investigated the glycosylation signature, as well as the regulated expression of galectin-1 and -3 in human duodenal samples of allergic and non-allergic children. Whereas galectin-1 was predominantly localized in the epithelial compartment (epithelial cells and intraepithelial lymphocytes) and the underlying lamina propria (T cells, macrophages and plasma cells), galectin-3 was mainly expressed by crypt epithelial cells and macrophages in the lamina propria. Remarkably, expression of these galectins was not significantly altered in allergic versus non-allergic patients. Investigation of the glycophenotype of the duodenal inflammatory microenvironment revealed substantial alpha2-6-linked sialic acid bound to galactose in lamina propria plasma cells, macrophages and intraepithelial lymphocytes and significant levels of asialo core 1 O-glycans in CD68+ macrophages and enterocytes. Galectin-1 preferentially bound to neutrophils, plasma cells and enterocytes, while galectin-3 binding sites were mainly distributed on macrophages and intraepithelial lymphocytes. Notably, galectin-3, but not galectin-1 binding, was substantially increased in intraepithelial gut lymphocytes of allergic patients compared to non-allergic subjects, suggesting a potential role of galectin-3-glycan interactions in shaping epithelial-immune cell connections during allergic inflammatory processes.Fil: Mercer, Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata; ArgentinaFil: Guzman, Luciana. Provincia de Buenos Aires. Ministerio de Salud. Hospital de Niños "Sor María Ludovica" de la Plata; ArgentinaFil: Cueto Rua, Eduardo. Provincia de Buenos Aires. Ministerio de Salud. Hospital de Niños "Sor María Ludovica" de la Plata; ArgentinaFil: Drut, Ricardo. Provincia de Buenos Aires. Ministerio de Salud. Hospital de Niños "Sor María Ludovica" de la Plata; ArgentinaFil: Ahmed, H.. University of Maryland; Estados UnidosFil: Vasta, G. R.. University of Maryland; Estados UnidosFil: Toscano, Marta Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Rabinovich, Gabriel Adrián. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Docena, Guillermo H.. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata; Argentin

Convergence Acceleration for Multistage Time-Stepping Schemes

The convergence of a Runge-Kutta (RK) scheme with multigrid is accelerated by preconditioning with a fully implicit operator. With the extended stability of the Runge-Kutta scheme, CFL numbers as high as 1000 could be used. The implicit preconditioner addresses the stiffness in the discrete equations associated with stretched meshes. Numerical dissipation operators (based on the Roe scheme, a matrix formulation, and the CUSP scheme) as well as the number of RK stages are considered in evaluating the RK/implicit scheme. Both the numerical and computational efficiency of the scheme with the different dissipation operators are discussed. The RK/implicit scheme is used to solve the two-dimensional (2-D) and three-dimensional (3-D) compressible, Reynolds-averaged Navier-Stokes equations. In two dimensions, turbulent flows over an airfoil at subsonic and transonic conditions are computed. The effects of mesh cell aspect ratio on convergence are investigated for Reynolds numbers between 5.7 x 10(exp 6) and 100.0 x 10(exp 6). Results are also obtained for a transonic wing flow. For both 2-D and 3-D problems, the computational time of a well-tuned standard RK scheme is reduced at least a factor of four

H_{2} adsorption on multiwalled carbon nanotubes at low temperatures and low pressures

We present an experimental study on H_{2} adsorption on multiwalled carbon nanotubes (MWCNTs) at low temperatures (12–30 K) and low pressures (2×10^{-5}  Torr) using the temperature programmed desorption technique. Our results show that the molecular hydrogen uptake increases nearly exponentially from 6×10^{-9}  wt. % at 24.5 K to 2×10^{-7}  wt. % at 12.5 K and that the desorption kinetics is of the first order. Comparative measurements indicate that MWCNTs have an adsorption capacity about two orders higher than that of activated carbon (charcoal) making them a possible candidate as hydrogen cryosorber for eventual applications in accelerators and synchrotrons

Lacking catalase, a protistan parasite draws on its photosynthetic ancestry to complete an antioxidant repertoire with ascorbate peroxidase

Background: Antioxidative enzymes contribute to a parasite's ability to counteract the host's intracellular killing mechanisms. The facultative intracellular oyster parasite, Perkinsus marinus, a sister taxon to dinoflagellates and apicomplexans, is responsible for mortalities of oysters along the Atlantic coast of North America. Parasite trophozoites enter molluscan hemocytes by subverting the phagocytic response while inhibiting the typical respiratory burst. Because P. marinus lacks catalase, the mechanism(s) by which the parasite evade the toxic effects of hydrogen peroxide had remained unclear. We previously found that P. marinus displays an ascorbate-dependent peroxidase (APX) activity typical of photosynthetic eukaryotes. Like other alveolates, the evolutionary history of P. marinus includes multiple endosymbiotic events. The discovery of APX in P. marinus raised the questions: From which ancestral lineage is this APX derived, and what role does it play in the parasite's life history? Results: Purification of P. marinus cytosolic APX activity identified a 32 kDa protein. Amplification of parasite cDNA with oligonucleotides corresponding to peptides of the purified protein revealed two putative APX-encoding genes, designated PmAPX1 and PmAPX2. The predicted proteins are 93% identical, and PmAPX2 carries a 30 amino acid N-terminal extension relative to PmAPX1. The P. marinus APX proteins are similar to predicted APX proteins of dinoflagellates, and they more closely resemble chloroplastic than cytosolic APX enzymes of plants. Immunofluorescence for PmAPX1 and PmAPX2 shows that PmAPX1 is cytoplasmic, while PmAPX2 is localized to the periphery of the central vacuole. Three-dimensional modeling of the predicted proteins shows pronounced differences in surface charge of PmAPX1 and PmAPX2 in the vicinity of the aperture that provides access to the heme and active site. Conclusions: PmAPX1 and PmAPX2 phylogenetic analysis suggests that they are derived from a plant ancestor. Plant ancestry is further supported by the presence of ascorbate synthesis genes in the P. marinus genome that are similar to those in plants. The localizations and 3D structures of the two APX isoforms suggest that APX fulfills multiple functions in P. marinus within two compartments. The possible role of APX in free-living and parasitic stages of the life history of P. marinus is discussed.Fil: Schott, Eric. University Of Maryland. Biotechnology Institute. Center Of Marine Biotechnology; Estados UnidosFil: Di Lella, Santiago. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Bachvaroff, Tsvetan R.. University Of Maryland. Biotechnology Institute. Center Of Marine Biotechnology; Estados UnidosFil: Amzel, León Mario. University Johns Hopkins; Estados UnidosFil: Vasta, Gerardo. University Of Maryland. Biotechnology Institute. Center Of Marine Biotechnology; Estados Unido

A case of double cystic esophageal duplication in VACTERL syndrome: the first case report and a review of the literature

BackgroundAn esophageal duplication cyst (EDC) is a rare malformation resulting from the embryonic foregut. VACTERL syndrome is a genetic disorder affecting many systems of the human body. We report the first case of VACTERL syndrome associated to asymptomatic double EDC.Case reportA girl with anorectal malformation and rectovestibular fistula, kidney malformation, and various vertebral defects came to our attention at the time of birth. VACTERL disease was diagnosed. She underwent Peña anoplasty at 4 months of life without complications. MRI was conducted at the age of 2. It accidentally showed a double esophageal duplication (12 mm × 35 mm × 10 mm) at the D7–D9 level. We planned a thoracoscopy; previous intraoperative esophagogastroduodenoscopy showed an external compression of the native esophagus. Two duplicated esophageal lesions were removed. The patient made an uneventful recovery and was completely asymptomatic at long-term follow-up.ConclusionsVACTERL syndrome is still a not well-defined disease. Based on the current literature, this is the first case of a double esophageal duplication in a patient affected by VACTERL syndrome. According to us, the thoracoscopic approach of esophageal duplications can be followed by experts. Complete surgical excision is possible even if the cyst shares a common muscular wall with the esophagus. For this reason, we suggest to close the muscular wall by a simple interrupted suture