- Maps and sensorimotor transformations for eye-head gaze shifts: Role of the midbrain superior colliculus. [Journal Article]
- PBProg Brain Res 2019; 249:19-33
- Single-unit recordings in head-restrained monkeys indicated that the population of saccade-related cells in the midbrain Superior Colliculus (SC) encodes the kinematics of desired straight saccade tr…
Single-unit recordings in head-restrained monkeys indicated that the population of saccade-related cells in the midbrain Superior Colliculus (SC) encodes the kinematics of desired straight saccade trajectories by the cumulative number of spikes. In addition, the nonlinear main sequence of saccades (their amplitude-peak velocity saturation) emerges from a spatial gradient of peak-firing rates of collicular neurons, rather than from neural saturation at brainstem burst generators. We here extend this idea to eye-head gaze shifts and illustrate how the cumulative spike-count in head-unrestrained monkeys relates to the desired gaze trajectory and its kinematics. We argue that the output of the motor SC is an abstract desired gaze-motor signal, which drives in a feedforward way the instantaneous kinematics of ongoing gaze shifts, including the strong influence of initial eye position on gaze kinematics. We propose that the neural population acts as a vectorial gaze pulse-generator for eye-head saccades, which is subsequently decomposed into signals that drive both motor systems in appropriate craniocentric reference frames within a dynamic gaze-velocity feedback loop.
- Analysis of Physcomitrella Phytochrome Mutants via Phototropism and Polarotropism. [Journal Article]
- MMMethods Mol Biol 2019; 2026:225-236
- In mosses such as Physcomitrella patens phytochrome photoreceptors steer directional/vectorial responses to unilateral/polarized light. In this chapter, we describe procedures to assay phototropism a…
In mosses such as Physcomitrella patens phytochrome photoreceptors steer directional/vectorial responses to unilateral/polarized light. In this chapter, we describe procedures to assay phototropism and polarotropism quantitatively in wild type and mutant lines. Protonemata are placed on agar-based medium in square Petri dishes in darkness for 1 week, allowing caulonemata to develop and grow negatively gravitropically. For phototropism, the dishes are placed vertically in black boxes and unilaterally irradiated with continuous red light. For polarotropism, Petri dishes are placed horizontally and irradiated with linearly polarized red light from above. After irradiation, the filaments are photographed using a macroscope with CCD camera and the bending angles measured using image processing software. The data are transfered to a spreadsheet program, placed into 10° bending angle classes and illustrated using a circular histogram.
- Brain Endothelial Cells Release Apical and Basolateral Microparticles in Response to Inflammatory Cytokine Stimulation: Relevance to Neuroinflammatory Stress? [Journal Article]
- FIFront Immunol 2019; 10:1455
- Microparticles (MP) are regarded both as biomarkers and mediators of many forms of pathology, including neurovascular inflammation. Here, we characterized vectorial release of apical and basolateral …
Microparticles (MP) are regarded both as biomarkers and mediators of many forms of pathology, including neurovascular inflammation. Here, we characterized vectorial release of apical and basolateral MPs (AMPs and BMPs) from control and TNF-α/IFN-γ treated human brain endothelial monolayers, studied molecular composition of AMPs and BMPs and characterized molecular pathways regulating AMP and BMP release. The effects of AMPs and BMPs on blood-brain barrier properties and human brain microvascular smooth muscle tonic contractility in vitro were also evaluated. We report that human brain microvascular endothelial cells release MPs both apically and basolaterally with both AMP and BMP release significantly increased following inflammatory cytokine challenge (3.5-fold and 3.9-fold vs. control, respectively). AMPs and BMPs both carry proteins derived from parent cells including those in BBB junctions (Claudin-1, -3, -5, occludin, VE-cadherin). AMPs and BMPs represent distinct populations whose release appears to be regulated by distinctly separate molecular pathways, which depend on signaling from Rho-associated, coiled-coil containing protein kinase (ROCK), calpain as well as cholesterol depletion. AMPs and BMPs modulate functions of neighboring cells including BBB endothelial solute permeability and brain vascular smooth muscle contractility. While control AMPs enhanced brain endothelial barrier, cytokine-induced AMPs impaired BBB. Cytokine-induced but not control BMPs significantly impaired human brain smooth muscle contractility as early as day 1. Taken together these results indicate that AMPs and BMPs may contribute to neurovascular inflammatory disease progression both within the circulation (AMP) and in the brain parenchyma (BMP).
- Early Studies on the Surface Epithelium of Mammalian Airways. [Journal Article]
- AJAm J Physiol Lung Cell Mol Physiol 2019 Jul 17
- This article traces the beginnings of the various areas of physiological research on airway epithelium. First mentioned in 1602, it was not until 1834 that it was found to be ciliated. Goblet and bas…
This article traces the beginnings of the various areas of physiological research on airway epithelium. First mentioned in 1602, it was not until 1834 that it was found to be ciliated. Goblet and basal cells were described in 1852 to be followed by about 10 other epithelial cell types (the most recent in 2018). It also contains nerve endings and resident leukocytes. Mucociliary clearance was documented in 1835, but the first studies on the ciliary beat cycle did not appear until 1890, and a definitive description was not published until 1981. It was established in 1932 that goblet cells in the cat trachea were unresponsive to cholinergic agents. But, only since 1980, or so, has any significant progress been made on what does cause them to degranulate. Active transfer of salts across epithelia creates local osmotic gradients that drive transepithelial water flows. Vectorial salt transport was first described for airway epithelium in 1968, and the associated volume flows were measured in 1981. Evidence that airway epithelium releases signaling molecules first appeared in 1981. Since then, scores of molecules have been identified. The pace of research in most areas increased dramatically after the development of confluent, polarized cultures of airway epithelium in the early 1980s.
- Intensity and spin anisotropy of three-dimensional polarization states. [Journal Article]
- OLOpt Lett 2019 Jul 15; 44(14):3578-3581
- Anisotropy is a natural feature of polarization states, and only fully random three-dimensional (3D) states exhibit complete isotropy. In general, differences between the strengths of the electric fi…
Anisotropy is a natural feature of polarization states, and only fully random three-dimensional (3D) states exhibit complete isotropy. In general, differences between the strengths of the electric field components along the three orthogonal directions give rise to intensity anisotropy. Moreover, polarization states involve an average spin whose inherent vectorial nature constitutes a source of spin anisotropy. In this work, appropriate descriptors are identified to characterize quantitatively the levels of intensity anisotropy and spin anisotropy of a general 3D polarization state, leading to a novel interpretation for the degree of polarimetric purity as a measure describing the overall polarimetric anisotropy of a 3D optical field. The mathematical representation, as well as the physical features of completely intensity-isotropic 3D polarization states with a maximum spin anisotropy, are also examined. The results provide new insights into the polarimetric field structure of random 3D electromagnetic light states.
- Depletion of Host Cell Focal Adhesion Kinase Increases the Susceptibility to Invasion by Trypanosoma cruzi Metacyclic Forms. [Journal Article]
- FCFront Cell Infect Microbiol 2019; 9:231
- Focal adhesion kinase (FAK), a cytoplasmic protein tyrosine kinase (PTK), is implicated in diverse cellular processes, including the regulation of F-actin dynamics. Host cell F-actin rearrangement is…
Focal adhesion kinase (FAK), a cytoplasmic protein tyrosine kinase (PTK), is implicated in diverse cellular processes, including the regulation of F-actin dynamics. Host cell F-actin rearrangement is critical for invasion of Trypanosoma cruzi, the protozoan parasite that causes Chagas disease. It is unknown whether FAK is involved in the internalization process of metacyclic trypomastigote (MT), the parasite form that is important for vectorial transmission. MT can enter the mammalian host through the ocular mucosa, lesion in the skin, or by the oral route. Oral infection by MT is currently a mode of transmission responsible for outbreaks of acute Chagas disease. Here we addressed the question by generating HeLa cell lines deficient in FAK. Host cell invasion assays showed that, as compared to control wild type (WT) cells, FAK-deficient cells were significantly more susceptible to parasite invasion. Lysosome spreading and a disarranged actin cytoskeleton, two features associated with susceptibility to MT invasion, were detected in FAK-deficient cells, as opposed to WT cells that exhibited a more organized F-actin arrangement, and lysosomes concentrated in the perinuclear area. As compared to WT cells, the capacity of FAK-deficient cells to bind a recombinant protein based on gp82, the MT surface molecule that mediates invasion, was higher. On the other hand, when treated with FAK-specific inhibitor PF573228, WT cells exhibited a dense meshwork of actin filaments, lysosome accumulation around the nucleus, and had increased resistance to MT invasion. In cells treated with PF573228, the phosphorylation levels of FAK were reduced and, as a consequence of FAK inactivation, diminished phosphorylation of extracellular signal-regulated protein kinases (ERK1/2) was observed. Fibronectin, known to impair MT invasion, induced the formation of thick bundles of F-actin and ERK1/2 dephosphorylation.
- Vorticity: Simplifying the analysis of the current density. [Journal Article]
- JCJ Comput Chem 2019 Jul 07
- The induced current density (J(r)) provides useful information about the electronic structure of molecules under a magnetic field (B). However, the analysis of its topology is cumbersome because of i…
The induced current density (J(r)) provides useful information about the electronic structure of molecules under a magnetic field (B). However, the analysis of its topology is cumbersome because of its vectorial nature. We show that its tropicity (direction of rotation) and its strength can be compressed in the triple product B ⋅ ∇ × J(r) (tpJ(r)) that is a scalar field. The topology of tpJ(r) has clear similarities to the Laplacian of the electron density. Additionally, the topology of aromatic and antiaromatic compounds is notoriously different. The vorticity of J(r) is helpful to define the circulation of the current density, C, that contrary to other methods, can be easily defined for individual rings in polycyclic molecules. This allows tpJ(r) to clearly reproduce the Clar's structure of polycyclic aromatic hydrocarbons. © 2019 Wiley Periodicals, Inc.
- Activation of Immune Genes in Leafhoppers by Phytoplasmas and Symbiotic Bacteria. [Journal Article]
- FPFront Physiol 2019; 10:795
- Insect immunity is a crucial process in interactions between host and microorganisms and the presence of pathogenic, commensal, or beneficial bacteria may result in different immune responses. In Hem…
Insect immunity is a crucial process in interactions between host and microorganisms and the presence of pathogenic, commensal, or beneficial bacteria may result in different immune responses. In Hemiptera vectors of phytoplasmas, infected insects are amenable to carrying high loads of phytopathogens, besides hosting other bacterial affiliates, which have evolved different strategies to be retained; adaptation to host response and immunomodulation are key aspects of insect-symbiont interactions. Most of the analyses published to date has investigated insect immune response to pathogens, whereas few studies have focused on the role of host immunity in microbiota homeostasis and vectorial capacity. Here the expression of immune genes in the leafhopper vector of phytoplasmas Euscelidius variegatus was investigated following exposure to Asaia symbiotic bacteria, previously demonstrated to affect phytoplasma acquisition by leafhoppers. The expression of four genes related to major components of immunity was measured, i.e., defensin, phenoloxidase, kazal type 1 serine protease inhibitor and Raf, a component of the Ras/Raf pathway. The response was separately tested in whole insects, midguts and cultured hemocytes. Healthy individuals were assessed along with specimens undergoing early- and late-stage phytoplasma infection. In addition, the adhesion grade of Asaia strains was examined to assess whether symbionts could establish a physical barrier against phytoplasma colonization. Our results revealed a specific activation of Raf in midguts after double infection by Asaia and flavescence dorée phytoplasma. Increased expression was observed already in early stages of phytoplasma colonization. Gut-specific localization and timing of Raf activation are consistent with the role played by Asaia in limiting phytoplasma acquisition by E. variegatus, supporting the involvement of this gene in the anti-pathogen activity. However, limited attachment capability was found for Asaia under in vitro experimental conditions, suggesting a minor contribution of physical phytoplasma exclusion from the vector gut wall. By providing evidence of immune modulation played by Asaia, these results contribute to elucidating the molecular mechanisms regulating interference with phytoplasma infection in E. variegatus. The involvement of Raf suggests that in the presence of reduced immunity (reported in Hemipterans), immune genes can be differently regulated and recruited to play additional functions, generally played by genes lost by hemipterans.
- In Search of Congenital Chagas Disease in the Sierra Nevada de Santa Marta, Colombia. [Journal Article]
- AJAm J Trop Med Hyg 2019 Jul 01
- Chagas disease remains a major impediment to sustainable socioeconomic development in Latin America. Transplacental transmission explains the persistence of transmission in urban areas, in non-endemi…
Chagas disease remains a major impediment to sustainable socioeconomic development in Latin America. Transplacental transmission explains the persistence of transmission in urban areas, in non-endemic regions, and in areas with an established interrupted vectorial transmission. One of every five cases of congenital Chagas disease in the world occurs in Colombia and Venezuela. The massive migration of impoverished populations from neighboring Venezuela has worsened the situation creating a humanitarian crisis in Northeastern Colombia, including the Sierra Nevada de Santa Marta. The prevalence of Chagas infection among pregnant women in these areas is higher than the national average, and the public health resources are insufficient. This perspective discusses the associated increased morbidity and mortality of congenital Chagas in this region, where stigmatization contributes to the impression among health authorities and the general population that it affects indigenous communities only. The monitoring and control of congenital Chagas disease in the Sierra Nevada of Santa Marta is a public health necessity that demands urgent and effective interventions.
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- Mapping the weak plasmonic transverse field by a dielectric-nanoparticle-on-film structure with ultra-high precision. [Journal Article]
- OEOpt Express 2019 Jun 24; 27(13):18980-18987
- Highly confined electromagnetic fields play a significant role in modern nano-optics, among which surface plasmon polaritons (SPPs) are outstanding because of their subwavelength and enhancement natu…
Highly confined electromagnetic fields play a significant role in modern nano-optics, among which surface plasmon polaritons (SPPs) are outstanding because of their subwavelength and enhancement nature. While many state-of-the-art methods have been proposed to uncover the field distribution of SPPs, it still faces challenge to map the weak transverse field component (the field tangential to the interface) of SPPs with high contrast and precision. We propose a direct imaging technique, which employs a dielectric-nanoparticle-on-metal-film (DNP-MF) structure as a near-field probe, to overcome this difficulty. The angular distribution of the scattering radiation from the structure is strongly polarization dependent. By extracting the scattering signals that are mainly induced by the horizontal polarization, the imaging of the weak plasmonic transverse field with high precision can be achieved. The mappings of SPPs distributions excited by various vector beams were performed in experiment, which accord excellent with theory. This technique provides a new approach for near-field imaging with high contrast and reliability, which is expected to be valuable for studying the vectorial features of SPPs such as transverse spin, spin-orbit interactions, etc.