Bilateral Cryptophthalmus: First Case Report from Nepal

Introduction: Cryptophthalmus is characterized by a partial or complete casing of the eyeball by the skin. Cryptophthalmus alongside other systemic abnormalities is well-known as Fraser syndrome. It is an unusual genetic disorder with limited literature. The complexities of disease and limited experience pose challenges in its management. Case: A two-day-male neonate was brought by his parents with a complaint of swelling in the right orbital region and deformed left eye since birth. Examination revealed bilobed globular swelling in the right orbital region covered by a continuous sheet of skin from forehead to cheek with no visible ocular tissue. On the left side, there was absence of upper lid margin and eyelashes and superior symblepharon. He also had bilateral ear abnormalities and right renal agenesis. Surgical intervention was done. On the right side, removal of the globe and cyst was done. On the left side, upper eyelid reconstruction with symblepharon release was done with amniotic membrane transplantation. Conclusions: The management of cryptophthalmus is challenging. Reconstructive surgeries allow cosmesis but useful vision is rarely gained. This is the first case report from Nepal to date to the best of our knowledge.

Game of Tissues: How the Epidermis Thrones C. elegans Shape

The versatility of epithelial cell structure is universally exploited by organisms in multiple contexts. Epithelial cells can establish diverse polarized axes within their tridimensional structure which enables them to flexibly communicate with their neighbors in a 360° range. Hence, these cells are central to multicellularity, and participate in diverse biological processes such as organismal development, growth or immune response and their misfunction ultimately impacts disease. During the development of an organism, the first task epidermal cells must complete is the formation of a continuous sheet, which initiates its own morphogenic process. In this review, we will focus on the C. elegans embryonic epithelial morphogenesis. We will describe how its formation, maturation, and spatial arrangements set the final shape of the nematode C. elegans. Special importance will be given to the tissue-tissue interactions, regulatory tissue-tissue feedback mechanisms and the players orchestrating the process.

Dissecting the neural divide: A continuous neurectoderm gives rise to both the olfactory placode and olfactory bulb

The olfactory epithelia arise from morphologically identifiable structures called olfactory placodes. Sensory placodes are generally described as being induced from the ectoderm suggesting that their development is separate from the coordinated cell movements generating the central nervous system. Previously, we have shown that the olfactory placodes arise from a large field of cells bordering the telencephalic precursors in the neural plate, and that cell movements, not cell division, underlie olfactory placode morphogenesis. Subsequently by image analysis, cells were tracked as they moved in the continuous sheet of neurectoderm giving rise to the peripheral (olfactory organs) and central (olfactory bulbs) nervous system (Torres-Paz and Whitlock, 2014). These studies lead to a model whereby the olfactory epithelia develop from within the border of the neural late and are a neural tube derivative, similar to the retina of the eye (Torres-Paz and Whitlock, 2014; Whitlock, 2008). Here we show that randomly generated clones of cells extend across the morphologically differentiated olfactory placodes/olfactory bulbs, and test the hypothesis that these structures are patterned by a different level of distal-less (dlx) gene expression subdividing the anterior neurectoderm into OP precursors (high Dlx expression) and OB precursors (lower Dlx expression). Manipulation of DLX protein and RNA levels resulted in morphological changes in the size of the olfactory epithelia and olfactory bulb. Thus, the olfactory epithelia and bulbs arise from a common neurectodermal region and develop in concert through coordinated morphological movements.

Physical basis of lumen shape and stability in a simple epithelium

A continuous sheet of epithelial cells surrounding a hollow opening, or lumen, defines the basic topology of numerous organs. De novo lumen formation is a central feature of embryonic development whose dysregulation leads to congenital and acquired diseases of the kidney and other organs. Hydrostatic pressure has been proposed to drive lumen expansion, a view that is supported by recent experiments in the mouse blastocyst. High luminal pressure should produce lumen surfaces that bow outwards toward the surrounding cells. However, lumens formed in other embryonic tissues adopt highly irregular shapes, with cell apical faces that are bowed inward, suggesting that pressure may not be the dominant contributor to lumen growth in all cases. We used three-dimensional live-cell imaging to study the physical mechanism of lumen formation in Madin Darby Canine Kidney (MDCK) cell spheroids, a canonical cell-culture model for lumenogenesis. Our experiments revealed that neither lumen pressure nor the actomyosin cytoskeleton were required to maintain lumen shape or stability. Instead, we find that, in our model system, lumen shape results from simple geometrical factors tied to the establishment of apico-basal polarity. A quantitative physical model that incorporates cell geometry, cortical tension, and intraluminal pressure can account for our observations as well as cases in which pressure indeed plays a dominant role. Our results thus support a unifying physical mechanism for the formation of luminal openings in a variety of physiological contexts.

Viscoelastic liquid curtains: experimental results on the flow of a falling sheet of polymer solution

We experimentally investigate the extensional flow of a sheet – or curtain – of viscoelastic liquid falling freely from a slot at constant flow rate under gravity. Extruded liquids are aqueous solutions of flexible polyethylene oxide (PEO) and of semi-rigid partially hydrolysed polyacrylamide (HPAM) with low shear viscosities. Velocimetry measurements reveal that the mean velocity field $U(z)$ (where $z$ is the distance from the slot exit) does not reduce to a free fall. More precisely, we show that the liquid falls initially with sub-gravitational accelerations up to a distance from the slot which scales as $g\unicode[STIX]{x1D70F}_{fil}^{2}$ (where $g$ is gravity and $\unicode[STIX]{x1D70F}_{fil}$ is the extensional relaxation time of the liquid) due to the stretching of polymer molecules. Beyond this elastic length, inertia dominates and the local acceleration reaches the asymptotic free-fall value $g$. The length of the sub-gravitational part of the curtain is shown to be much larger than the equivalent viscous length $((4\unicode[STIX]{x1D702}/\unicode[STIX]{x1D70C})^{2}/g)^{1/3}$ for Newtonian liquids of density $\unicode[STIX]{x1D70C}$ and dynamic viscosity $\unicode[STIX]{x1D702}$ which is usually small compared to the curtain length. By analogy with Newtonian curtains, we show that the velocity field $U(z)$ rescales on a master curve. Besides, the flow is shown to be only weakly affected by the history of polymer deformations in the die upstream of the curtain. Furthermore, investigations on the curtain stability reveal that polymer addition reduces the minimum flow rate required to maintain a continuous sheet of liquid.

Top Two News Words (By Hour)

The Top Two News Words project began in 2007 as a gallery piece featuring a computer and dot matrix printer linked to an online parsing routine which gathered headlines from fifteen major news sources hourly, and analyzed and reduced these headlines to the two most frequently occurring words. The resulting pairs were printed each hour on a continuous sheet of computer paper, creating a linear document of the 24/7/365 news cycle. Since 2008, the online component of the piece has been running automatically, without its physical half, publishing hourly word pairs via RSS and on Twitter and building an online archive of nearly 90,000 hours of news. Top Two News Words has consistently evoked questions of bias from its audience: “Why only these sources? Why only sources in English? Who are you to decide what is a major news source?” This is, of course, one of the desired outcomes of the project. A deeper question, which is reflected in the recent controversy and surprise over Facebook’s use of human curators for trending topics, is why don’t we investigate for bias in supposedly neutral online news aggregators such as Google? And, is it even possible to filter news programmatically without bias? I seek to use this project to illustrate the simple concept that curation, bias and reduction are not the antithesis of awareness in a world of continuous, direct news but are an essential part of navigating and understanding this world.

Do the Different Sensory Areas Within the Cat Anterior Ectosylvian Sulcal Cortex Collectively Represent a Network Multisensory Hub?

Current theory supports that the numerous functional areas of the cerebral cortex are organized and function as a network. Using connectional databases and computational approaches, the cerebral network has been demonstrated to exhibit a hierarchical structure composed of areas, clusters and, ultimately, hubs. Hubs are highly connected, higher-order regions that also facilitate communication between different sensory modalities. One computationally identified network hub is the visual area of the Anterior Ectosylvian Sulcal cortex (AESc) of the cat. The Anterior Ectosylvian Visual area (AEV) is but one component of the AESc since the latter also includes the auditory (Field of the Anterior Ectosylvian Sulcus — FAES) and somatosensory (Fourth somatosensory representation — SIV) areas. To better understand the nature of cortical network hubs, the present report reviews the biological features of the AESc. Within the AESc, each area has extensive external cortical connections as well as among one another. Each of these core representations is separated by a transition zone characterized by bimodal neurons that share sensory properties of both adjoining core areas. Finally, core and transition zones are underlain by a continuous sheet of layer 5 neurons that project to common output structures. Altogether, these shared properties suggest that the collective AESc region represents a multiple sensory/multisensory cortical network hub. Ultimately, such an interconnected, composite structure adds complexity and biological detail to the understanding of cortical network hubs and their function in cortical processing.

Impact of Graphene on the Polarizability of a Neighbour Nanoparticle: A Dyadic Green's Function Study

We discuss the renormalization of the polarizability of a nanoparticle in the presence of either (i) a continuous graphene sheet or (ii) a plasmonic graphene grating, taking into account retardation effects. Our analysis demonstrates that the excitation of surface plasmon-polaritons in graphene produces a large enhancement of the real and imaginary parts of the renormalized polarizability. We show that the imaginary part can be changed by a factor of up to 100 relatively to its value in the absence of graphene. We also show that the resonance in the case of the grating is narrower than in the continuous sheet. In the case of the grating it is shown that the resonance can be tuned by changing the grating geometric parameters.