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Human thymic epithelial cells express an endogenous lectin, galectin-1, which binds to core 2 O-glycans on thymocytes and T lymphoblastoid cells.
Thymic epithelial cells play a crucial role in the selection of developing thymocytes. Thymocyte-epithelial cell interactions involve a number of adhesion molecules, including members of the integrin and immunoglobulin superfamilies. We found that human thymic epithelial cells synthesize an endogenous lectin, galectin-1, which binds to oligosaccharide ligands on the surface of thymocytes and T lymphoblastoid cells. Binding of T lymphoblastoid cells to thymic epithelial cells was inhibited by antibody to galectin-1 on the epithelial cells, and by two antibodies, T305 and 2B11, that recognize carbohydrate epitopes on the T cell surface glycoproteins CD43 and CD45, respectively. T lymphoblastoid cells and thymocytes bound recombinant galectin-1, as demonstrated by flow cytometric analysis, and lectin binding was completely inhibited in the presence of lactose. The degree of galectin-1 binding to thymocytes correlated with the maturation stage of the cells, as immature thymocytes bound more galectin-1 than did mature thymocytes. Preferential binding of galectin-1 to immature thymocytes may result from regulated expression of preferred oligosaccharide ligands on those cells, since we found that the epitope recognized by the T305 antibody, the core 2 O-glycan structure on CD43, was expressed on cortical, but not medullary cells. The level of expression of the UDP-GlcNAc:Gal beta 1,3GalNAc-R beta 1, 6GlcNAc transferase (core 2 beta 1, 6 GlcNAc transferase, or C2GnT), which creates the core 2 O-glycan structure, correlated with the glycosylation change between cortical and medullary cells. Expression of mRNA encoding the C2GnT was high in subcapsular and cortical thymocytes and low in medullary thymocytes, as demonstrated by in situ hybridization. These results suggest that galectin-1 participates in thymocyte-thymic epithelial cell interactions, and that this interaction may be regulated by expression of relevant oligosaccharide ligands on the thymocyte cell surface
Intruding implements: a pictorial review of retained surgical foreign objects in neuroradiology
Intra-cranial and spinal foreign body reactions represent potential complications of medical procedures. Their diagnosis may be challenging as they frequently show an insidious clinical presentation and can mimic other life-threatening conditions. Their pathophysiological mechanism is represented by a local inflammatory response due to retained or migrated surgical elements. Cranial interventions may be responsible for the presence of retained foreign objects represented by surgical materials (such as sponges, bone wax, and Teflon). Spinal diagnostic and therapeutic procedures, including myelography, chordotomy, vertebroplasty, and device implantation, are another potential source of foreign bodies. These reactions can also follow material migration or embolization, for example in the case of Lipiodol, Teflon, and cement vertebroplasty. Imaging exams, especially CT and MRI, have a central role in the differential diagnosis of these conditions together with patient history. Neuroradiological findings are dependent on the type of material that has been left in or migrated from the surgical area. Knowledge of these entities is relevant for clinical practice as the correct identification of foreign bodies and related inflammatory reactions, material embolisms, or migrations can be difficult. This pictorial review reports neuroradiological semeiotics and differential diagnosis of foreign body-related imaging abnormalities in the brain and spine
Galectin-1, an Endogenous Lectin Produced by Thymic Epithelial Cells, Induces Apoptosis of Human Thymocytes
Galectin-1, a ÎČ-galactoside binding protein, is produced by thymic epithelial cells and binds to human thymocytes. We have previously reported that galectin-1 induces the apoptosis of activated T lymphocytes. Because the majority of thymocytes die via apoptosis while still within the thymus, we tested whether galectin-1 could induce the apoptosis of these cells. We now report that in vitro exposure to galectin-1 induced apoptosis of two subsets of CD4lo CD8lo thymocytes. The phenotypes of susceptible thymocytes were consistent with that of both negatively selected and nonselected cells. Galectin-1âinduced apoptosis was enhanced by preexposure of thymocytes to antibody to CD3, suggesting that galectin-1 may be a participant in T-cellâ receptor mediated apoptosis. In contrast, pretreatment of thymocytes with dexamethasone had no effect on galectin-1 susceptibility. We noted that 71% of the cells undergoing apoptosis after galectin-1 treatment had a DNA content greater than 2N, indicating that proliferating thymocytes were most sensitive to galectin-1. We propose that galectin-1 plays a role in the apoptosis of both negatively selected and nonselected thymocytes, and that the susceptibility of thymocytes to galectin-1 is regulated, in part, by entry or exit from the cell cycle
Neuroradiological findings in Alagille syndrome
Alagille syndrome (ALGS) is a multisystemic disease caused by mutations in genes of Notch pathway, which regulates embryonic cell differentiation and angiogenesis. Clinically, ALGS is characterized by cholestasis, cardiac defects, characteristic facial features, skeletal and ophthalmologic abnormalities. The aim of this review is to illustrate neuroradiological findings in ALGS, which are less well-known and prevalent, including cerebrovascular anomalies (such as aneurysms, dolichoectasia, Moyamoya syndrome and venous peculiarities), Chiari 1 malformation, craniosynostosis, intracranial hypertension, and vertebral anomalies (namely butterfly vertebra, hemivertebra, and craniocervical junction anomalies). Rarer cerebral midline malformations and temporal bone anomalies have also been described
Searches for Stable Strangelets in Ordinary Matter: Overview and a Recent Example
Our knowledge on the possible existence in nature of stable exotic particles
depends solely upon experimental observation. Guided by this general principle
and motivated by theoretical hypotheses on the existence of stable particles of
strange quark matter, a variety of experimental searches have been performed.
We provide an introduction to the theoretical hypotheses, an overview of the
past searches, and a more detailed description of a recent search for
helium-like strangelets in the Earth's atmosphere using a sensitive laser
spectroscopy method
Color plasma oscillation in strangelets
The dispersion relation and damping rate of longitudinal color plasmons in
finite strange quark matter (strangelets) are evaluated in the limits of weak
coupling, low temperature, and long wavelength. The property of the QCD vacuum
surrounding a strangelet makes the frequency of the plasmons nearly the same as
the color plasma frequency of bulk matter. The plasmons are damped by their
coupling with individual excitations of particle-hole pairs of quarks, of which
the energy levels are discretized by the boundary. For strangelets of
macroscopic size, the lifetime of the plasmons is found to be proportional to
the size, as in the case of the usual plasma oscillations in metal
nanoparticles.Comment: 9 pages (REVTeX), 2 Postscript figures, to be published in Phys. Rev.
Effects of DensityâDriven Flows on the LongâTerm Morphodynamic Evolution of FunnelâShaped Estuaries
Subtidal flows driven by density gradients affect the tideâaveraged sediment transport in estuaries and, therefore, can influence their longâterm morphodynamic evolution. The threeâdimensional Coupled OceanâAtmosphereâWaveâSediment Transport modeling system is applied to numerically analyze the effects of baroclinicity and Earth\u27s rotation on the longâterm morphodynamic evolution of idealized funnelâshaped estuaries. The morphodynamic evolution in all the analyzed cases reproduced structures identified in many tideâdominated estuaries: a meandering region in the fluvialâtidal transition zone, a tidal maximum area close to the head, and a turbidity maxima region in the brackish zone. As the morphology of the estuaries evolved, the tidal propagation (including its asymmetry), the salinity gradient, and the strength of subtidal flows changed, which reflects the strong bathymetric control of these systems. The comparison with barotropic simulations showed that the threeâdimensional structure of the flow (induced by density gradients) has leading order effects on the morphodynamic evolution. Density gradientâdriven subtidal flows (1) promote nearâbed flood dominance and, consequently, the import of sediment into the estuary, (2) accelerate the morphodynamic evolution of the upper/middle estuary, (3) promote a more concave shape of the upper estuary and reduce the ebbâtidal delta volume, and (4) produce an asymmetric bathymetry and inhibit the formation of alternate bars that would form under barotropic conditions. This latter effect is the consequence of the combined effect of Earth\u27s rotation and baroclinicity
Phenological Mismatch Between Season Advancement and Migration Timing Alters Arctic Plant Traits
Climate change is creating phenological mismatches between herbivores and their plant resources throughout the Arctic. While advancing growing seasons and changing arrival times of migratory herbivores can have consequences for herbivores and forage quality, developing mismatches could also influence other traits of plants, such as aboveâ and belowâground biomass and the type of reproduction, that are often not investigated. In coastal western Alaska, we conducted a 3âyear factorial experiment that simulated scenarios of phenological mismatch by manipulating the start of the growing season (3 weeks early and ambient) and grazing times (3 weeks early, typical, 3 weeks late, or noâgrazing) of Pacific black brant (Branta bernicla nigricans), to examine how the timing of these events influence a primary goose forage species, Carex subspathacea. After 3 years, an advanced growing season compared to a typical growing season increased stem heights, standing dead biomass, and the number of inflorescences. Early season grazing compared to typical season grazing reduced aboveâ and belowâground biomass, stem height, and the number of tillers; while late season grazing increased the number of inflorescences and standing dead biomass. Therefore, an advanced growing season and late grazing had similar directional effects on most plant traits, but a 3âweek delay in grazing had an impact on traits 3â5 times greater than a similarly timed shift in the advancement of spring. In addition, changes in response to treatments for some variables, such as the number of inflorescences, were not measurable until the second year of the experiment, while other variables, such as root productivity and number of tillers, changed the direction of their responses to treatments over time. Synthesis. Factors affecting the timing of migration have a larger influence than earlier springs on an important forage species in the breeding and rearing habitats of Pacific black brant. The phenological mismatch prediction for this site of earlier springs and later goose arrival will likely increase aboveâ and belowâground biomass and sexual reproduction of the oftenâclonally reproducing C. subspathacea. Finally, the implications of mismatch may be difficult to predict because some variables required successive years of mismatch to respond
New Neuronal Subtypes With a "Pre-Pancreatic" Signature in the Sea Urchin Stongylocentrotus purpuratus
Neurons and pancreatic endocrine cells have a common physiology and express a similar toolkit of transcription factors during development. To explain these common features, it has been hypothesized that pancreatic cells most likely co-opted a pre-existing gene regulatory program from ancestral neurons. To test this idea, we looked for neurons with a âpre-pancreaticâ program in an early-branched deuterostome, the sea urchin. Only vertebrates have a proper pancreas, however, our lab previously found that cells with a pancreatic-like signature are localized within the sea urchin embryonic gut. We also found that the pancreatic transcription factors Xlox/Pdx1 and Brn1/2/4 co-localize in a sub-population of ectodermal cells. Here, we find that the ectodermal SpLox+ SpBrn1/2/4 cells are specified as SpSoxC and SpPtf1a neuronal precursors that become the lateral ganglion and the apical organ neurons. Two of the SpLox+ SpBrn1/2/4 cells also express another pancreatic transcription factor, the LIM-homeodomain gene islet-1. Moreover, we find that SpLox neurons produce the neuropeptide SpANP2, and that SpLox regulates SpANP2 expression. Taken together, our data reveal that there is a subset of sea urchin larval neurons with a gene program that predated pancreatic cells. These findings suggest that pancreatic endocrine cells co-opted a regulatory signature from an ancestral neuron that was already present in an early-branched deuterostome
The development of a risk-adjustment strategy to benchmark emergency medical service (EMS) performance in relation to out-of-hospital cardiac arrest in Australia and New Zealand
Introduction: The aim of this study was to develop a risk adjustment strategy, including effect modifiers, for benchmarking emergency medical service (EMS) performance for out-of-hospital cardiac arrest (OHCA) in Australia and New Zealand. Method: Using 2017â2019 data from the Australasian Resuscitation Outcomes Consortium (Aus-ROC) OHCA Epistry, we included adults who received an EMS attempted resuscitation for a presumed medical OHCA. Logistic regression was applied to develop risk adjustment models for event survival (return of spontaneous circulation at hospital handover) and survival to hospital discharge/30 days. We examined potential effect modifiers, and assessed model discrimination and validity. Results: Both OHCA survival outcome models included EMS agency and the Utstein variables (age, sex, location of arrest, witnessed arrest, initial rhythm, bystander cardiopulmonary resuscitation, defibrillation prior to EMS arrival, and EMS response time). The model for event survival had good discrimination according to the concordance statistic (0.77) and explained 28% of the variation in survival. The corresponding figures for survival to hospital discharge/30 days were 0.87 and 49%. The addition of effect modifiers did little to improve the performance of either model. Conclusion: The development of risk adjustment models with good discrimination is an important step in benchmarking EMS performance for OHCA. The Utstein variables are important in risk-adjustment, but only explain a small proportion of the variation in survival. Further research is required to understand what factors contribute to the variation in survival between EMS
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