polarity (Total 29288 Papers Found)

In preimplantation mouse development, the first cell lineages to be established are the trophectoderm (TE) and inner cell mass. TE possesses epithelial features, including apical-basal cell polarity and intercellular junctions, which are crucial to generate a fluid-filled cavity in the blastocyst. Homologs of the partitioning defective (par) genes in Caenorhabditis elegans are critical regulators of cell polarity. However, their roles in regulating TE differentiation and blastocyst formation rem ...
GAP-43, a neuron specific growth-associated protein, is selectively distributed to the axonal domain in developing neurons; it is absent from dendrites and their growth cones. Using immunofluorescence microscopy, we have further examined the distribution of GAP-43 during the development of hippocampal neurons in culture, in order to determine when this polarized distribution arises. Cultured hippocampal neurons initially extend several short processes which have the potential to become either ax ...
We have previously shown that addition of type 1 transforming growth factor-beta (TGFbeta1) to an exponentially growing population of mink lung CCl64 cells increases their average intermitotic time from 14.4 to 20.3 hours, predominantly by extending G1 from 7.5 to 13.5 hours. Here we have used the DRIMAPS system (digitally recorded interference microscopy with automatic phase-shifting) for obtaining data on cellular mass distribution, cell motility and morphology. We found no significant change ...
The goal of this study was to evaluate different neurotransmitters and their receptors that might be involved in retinotectal transmission in the goldfish. Sections of tectum were isolated and maintained in vitro while pharmacological agents were administered via the tissue bath. Field potentials were elicited by electrical stimulation of the optic nerve and recorded at 50 micron depth intervals, and profiles of current source densities (CSDs) were computed from the second spatial derivatives of ...
OBJECTIVE The duration of direct current (DC) iontophoresis is limited to 10- to 15-minute periods because of electrochemical burns from hydrogen and hydroxide ions generated by the DC current. A new iontophoretic device, the Lectro Patch, uses a low-frequency alternating current (AC). AC current is theorized to generate H+ ions during one phase and OH- when the current reverses polarity, thus possibly neutralizing pH changes and avoiding burns. This study examined this possibility and evaluated ...
Mass spectrometry has a basic limitation when human hemoglobin variants are analyzed, because it cannot resolve two globin chains that differ in mass by <6 Da. Several common beta-chain variants differ by 1 Da from normal and, hence, when present in heterozygotes, are not resolved from the normal beta-chain. Normal and variant chains appear together in the spectrum as a single entity, whose mass is the abundance weighted mean of the two chains. Here we show that such heterozygotes can be dete ...
RATIONALE Mass calibration in matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is currently obtained using mixtures of individual peptides. This procedure has several drawbacks, including laborious preparation, limited shelf life and unequal calibration mass spacing. Polyalanine, a simple to prepare polydisperse molar mass standard, alleviates these problems. METHODS Polyalanine is prepared by the typical protocols for biological sample analytics. RESULTS Polyalanine ...
The behaviour of ICMs isolated from early blastocysts of rabbit by microsurgery and incubated in cultural system in vitro, are varied according to the growing state of ICM. The band type growing extends from the proximal to the distal end, while the differentiation of cells in this kind initiates from the distal toward the proximal and gradually. The band type ICM possesses obvious polarity. The differentiation of different kind of cells appear one after another in order and the arrangement of d ...
  • Vernon French,
  • Journal of embryology and experimental morphology
  • 1978
Epidermal cells from different circumferential positions around the femur of Blabera craniifer can interact to form an intercalary regenerate. Removal of a longitudinal strip of integument (cuticle plus epidermis) from any position around the circumference leads to the cut edges healing, localized growth and intercalary regeneration of the missing section of the circumference, so that the resulting femur is approximately normal in size and pattern of cuticular structures. Grafting a longitudinal ...
In the recent years, much of the current research is focusing on the area of sentiment analysis. Sentiment analysis is the study of sentiments, which are posted on various review sites. In this paper, we propose a novel method which uses only three part of speech words yet effective in classification of the opinions at document level and sentence level. We employed different classifiers viz, Nearest Neighbor classifier, Centroid classifier, Naïve Bayes classifier and Voting classifier to classi ...
We propose and successfully demonstrate a novel approach to optically generate ultrawideband (UWB) pulse with switchable shape and polarity by using a polarization-maintaining fiber Bragg grating (PM-FBG) as frequency discriminator. Depending on the shape of the reflective spectrum of the PM-FBG, the system can function as a first- or second-order differentiator for the generation of Gaussian UWB monocycle or doublet pulses. Consequently, the shape and the polarity of the generated UWB pulse can ...
Abstract The reduced modified Ostrovsky equation is a reduction of the modified Korteweg-de Vries equation, in which the usual linear dispersive term with a third-order derivative is replaced by a linear non-local integral term, representing the effect of background rotation. Here we study the case when the cubic nonlinear term has the same polarity as the rotation term. This equation is integrable provided certain slope constraints are satisfied. We demonstrate, through theoretical analysis and ...
Neuronal precursor cells generated by stem cells in the subventricular zone (SVZ) migrate and differentiate into mature interneurons in the olfactory bulb (OB). The mechanisms responsible for the dynamic morphological changes in cells during this process are largely unknown. Wnt/planar cell polarity (PCP) signaling regulates various developmental events, including neuronal migration and neurite formation. Here, we studied the function of two components of the PCP pathway, Dishevelled2 and Van Go ...
Imaging biological structures by means of so-called farred, near infrared (NIR) fluorophores is becoming more and more important for their high sensitivity, excellent temporal and spatial resolution, and their potential for multichannel imaging. Being less or not at all interfered by biological background luminescence, these fluorophores are particularly suitable for biological labeling both in vitro and in vivo. Very recently, we have reported on the synthesis of a series of “clickable” dye ...
Heterogeneity in tumor immune responses is a poorly understood yet critical parameter for successful immunotherapy. In two doxycycline-inducible models where oncogenic H-RasG12V is targeted either to the epidermal basal/stem cell layer with a Keratin14-rtTA transgene (K14Ras), or committed progenitor/suprabasal cells with an Involucrin-tTA transgene (InvRas), we observed strikingly distinct tumor immune responses. On threshold doxycycline levels yielding similar Ras expression, tumor latency, an ...
BACKGROUND Polarization of tissue is achieved by asymmetric distribution of proteins and organelles within individual cells. However, existing quantitative assays to measure this asymmetry in an automated and unbiased manner suffer from significant limitations. RESULTS Here, we report a new way to assess protein and organelle localization in tissue based on correlative fluorescence analysis. As a proof of principle, we successfully characterized planar cell polarity dependent asymmetry in deve ...
The most vital test for a coder is, however, the subjective assessment. Although no detailed comparison of the different coders has been made, the DZM has been found to offer an acceptable quality' of speech while the DM and the modified coder offer toll quality speech at 40 kbitsfs. CONCLUSIONS We have presented an overview of some of the different methods of realizing a companded unity bit coder where the companding is carried out on the input signal while a linear coder is used to code this c ...
Broad-spectrum drug screening requires that all relevant substances be isolated, detected, and identified, regardless of their structure and/or polarity. To this end, systematic solid-phase extraction (SPE) approaches for drug isolation from biological fluids are required. Because speed and cost effectiveness are key issues in analytical toxicology, we have evaluated a disc-format extraction device for this purpose and compared the latter with an existing packed-bed column-format method. The dis ...
In a macrocyclic terbium complex incorporating a biaryl sensitiser, the observed variation of emission lifetime is shown to be determined by the solubility of oxygen in the solvent system and the relative energy of the chromophore excited state, rather than any dependence on solvent viscosity. ...
Lipopolysaccharide (LPS, also called endotoxin) is a pro-inflammatory constituent of gram negative bacteria and cyanobacteria, which causes a potential health risk in the process of routine urban application of reclaimed water, such as car wash, irrigation, scenic water refilling, etc. Previous studies indicated that the common disinfection treatment, chlorination, has little effect on endotoxin activity removal measured by Limulus amebocyte lysate (LAL) assay. However, in this study, significan ...
We explore the structure and thermodynamics of water clusters confined in nonpolar cavities. By calculating the grand-canonical partition function term by term, we show that small nonpolar cavities can be filled at equilibrium with highly structured water clusters. The structural and thermodynamic properties of these encapsulated water clusters are similar to those observed experimentally in the gas phase. Water filling is highly sensitive to the size of the cavity and the strength of the intera ...
Objectives. The goal of the present work is to apply a modified version previously developed method for detection of areas involved in epileptogenic circuits and the assessment of the therapeutic effects of Low Frequency Intracranial Theta-burst Electric Neuronal Stimulation (LFITNES). Methods. We use a novel paradigm for stimulation of the brain with 20Hz biphasic cyclic alternating polarity (BiCAP) and compute the relative phase clustering index (rPCI) from the evoked response. The putative th ...
An improved laser Doppler velocimeter (LDV) is described for applications where confocal backscatter geometry is required. The optical geometry of the new technique is virtually the same as had been successfully employed by other investigators, with the important difference that a Glan prism is substituted for the 50-50 reflective beam splitter normally used in this geometry. The result is the elimination of major optical losses due to the beam splitter yielding more than a threefold increase in ...
AMP-deaminase (AMP-DA) which deaminates AMP and dAMP, and cytosolic 5'nucleotidase (c5'N) which hydrolyses intracellular mononucleotides are two enzymes of the nucleotide catabolism which could be involved in the cell ability to prevent cytotoxic accumulation of deoxy-ATP. These enzymes were measured in various mouse lymphocyte subpopulations. AMP-DA levels were found similar in T and B slenocytes and in circulating lymphocytes but were 10-30 fold lower in thymocytes; The low AMP-DA level in thy ...
We define a new bio-inspired computational model for deciding 2-dimensional languages similar to those presented in [2] and [3]. The novel factor being the communication protocol, which is based on the polarity associated with the symbols on the picture frame. This model can be viewed as a 2-dimensional extension of the one presented in [1]. We compare the class of languages accepted by these networks to other classes of 2-dimensional languages, namely the classes of Local Languages and Tiling R ...
We report a highly conserved motif in the E-cadherin juxtamembrane domain that determines apical-lateral polarity by conferring both restricted mobility at the lateral membrane and transcytosis of apically mis-sorted protein to the lateral membrane. Mutations causing either increased lateral membrane mobility or loss of apical-lateral transcytosis result in partial mis-sorting of E-cadherin in Madin-Darby canine kidney cells. However, loss of both activities results in complete loss of polarity. ...
In Mexico, the first outbreaks suggestive of the circulation of the porcine epidemic diarrhea virus (PEDV) were identified at the beginning of July 2013. To identify the molecular characteristics of the PEDV Spike (S) gene in Mexico, 116 samples of the intestine and diarrhea of piglets with clinical signs of porcine epidemic diarrhea (PED) were obtained. Samples were collected from 14 farms located in six states of Mexico (Jalisco, Puebla, Sonora, Veracruz, Guanajuato, and Michoacán) from 2013 ...
NK cells provide host defense by killing viral-infected and cancerous cells through the secretion of preformed lytic granules. Polarization of the lytic granules toward the target cell is dependent on an intact microtubule (MT) network as well as MT motors. We have recently shown that DOCK8, a gene mutated in a primary immunodeficiency syndrome, is involved in NK cell killing in part through its effects on MT organizing center (MTOC) polarization. In this study, we identified Hook-related protei ...
The possibility of pattern recognition using optical matched filtering with noncoherent light was realized by Armitage and Lohmann. A holographic implementation of this idea was demonstrated by Lohmann, who also pointed out that a noncoherent system has several advantages over its coherent equivalent, the Vander Lugt Fourier-plane filter. The operation of the noncoherent system must be described in terms of intensity rather than complex amplitude, hence, any phase variations of the input data ca ...
OBJECTIVES Opioid-induced constipation persists as a challenge in the management of chronic pain treated with opioid therapy. Multiple opioid antagonists have been applied in attempt to combat the gastrointestinal side effects of opioid analgesia, however their lipid-soluble nature allows passage into the central nervous system and consequent antagonism of centrally mediated analgesia. In contrast, methylnaltrexone offers the advantage of peripheral receptor-specific opioid antagonism due to che ...
BACKGROUND Circumferential pulmonary vein isolation (CPVI), as the basal ablation strategy for treating atrial fibrillation (AF), not only isolates the connection between the left atrium (LA) and the pulmonary veins (PVs), but also induces extensive atrial endocardia damage. This could have an effect on the sinus pulse conduction in the LA and subsequently result in changes of P-wave characteristics of surface electrocardiogram (ECG). METHODS Fifty consecutive patients underwent CPVI for sympt ...
C R E D IT : N . K E V IT IY A G A L A / C IE N C E A prominent way for an organism to develop many different cell types is to have cells divide unequally, generating daughter cells that differ in composition and fate, and often also in size. The importance of this process, called asymmetric cell division, for the development of multicellular organisms is undisputed ( 1). On page 677 of this issue, Ou et al. ( 2) describe a mechanism for generating unequal-sized daughter cells that is based on c ...
The absorption spectra of aminocoumarin C151 in water and n-hexane solution are investigated by an explicit quantum chemical solvent model. We improved the efficiency of the frozen-density embedding scheme, as used in a former study on solvatochromism (J. Chem. Phys. 2005, 122, 094115) to describe very large solvent shells. The computer time used in this new implementation scales approximately linearly (with a low prefactor) with the number of solvent molecules. We test the ability of the frozen ...
The responses of 39 single units in the ventral cochlear nucleus of acute anesthetized guinea-pigs were studied with continuous electrical stimuli presented through a dual-channel implant in the scala tympani. Implants had four electrodes placed along the axis of the cochlea with 1 mm separations. With a specific pair (either apical or basal) of stimulating electrodes, about half of the units responded when current was flowing apically, while the rest responded to current in the opposite directi ...
Responses from two types of orientation-selective units of retinal origin were recorded extracellularly from their axon terminals in the medial sublaminae of tectal retinorecipient layer of immobilized cyprinid fish Carassius gibelio. Excitatory and inhibitory interactions in the receptive field were analyzed with two narrow stripes of optimal orientation flashing synchronously, one in the center and the other in different parts of the periphery. The general pattern of results was that the influ ...
The unwinding or 'unzipping' of duplex DNA to produce single-stranded DNA (ssDNA) is essential for all processes that involve a ssDNA template or reaction intermediate , including DNA replication, repair, recombination and transcription 1. Enzymes called DNA helicases catalyze this unwinding of duplex DNA in an energy-requiring reaction , using the energy provided by the NTPase activity intrinsic to all helicases. As we currently understand this conceptually simple but mechanistically complex re ...
Uncontrolled energization of unloaded transformers is usually associated with a large inrush current, several times larger than the rated transformer current. This transient can cause unfavourable consequences including reduction of transformer lifecycle, protective relay misoperations, and reduced power quality of the system. Controlled switching can efficiently eliminate these transients when energizing an unloaded transformer. The performances of controlled switching mainly depend on the opti ...
BACKGROUND Quorum Sensing (QS) is a mechanism used by bacteria to determine their physiological activities and coordinate gene expression based on cell to cell signaling. Many bacterial physiological functions are under the regulation of quorum sensing such as virulence, luminescence, motility, sporulation and biofilm formation. The aim of the present study was to isolate and characterize Quorum Sensing Inhibitory (QSI) substances from epiphytic bacteria residing on wild berries surfaces. METH ...
Cadherin has an intimate spatial relationship with actin filaments (AF) in various types of cells, forming the cell-to-cell adherens junction (AJ). We compared the AJ/AF relationship between non-polarized fibroblasts (NRK cells) and polarized epithelial cells (MTD-1A cells). E/P-cadherin, alpha-catenin, ZO-1 and vinculin were localized with reference to AF in these cells using laser scan microscopy as well as conventional light and electron microscopy. NRK cells adhered to each other at the tips ...
Outgrowth of distinct axonal and dendritic processes is essential for the development of the functional polarity of nerve cells. In cultures of neurons from the hippocampus, where the differential outgrowth of axons and dendrites is readily discernible, we have sought molecules that might underlie the distinct modes of elongation of these two types of processes. One particularly interesting protein is GAP-43 (also termed B-50, Fl or P-57), a neuron-specific, membrane-associated phosphoprotein wh ...
Congenital defects of neural tube closure (neural tube defects; NTDs) are among the commonest and most severe disorders of the fetus and newborn. Disturbance of any of the sequential events of embryonic neurulation produce NTDs, with the phenotype (eg anencephaly, spina bifida) varying depending on the region of neural tube that remains open. While mutation of > 200 genes is known to cause NTDs in mice, the pattern of occurrence in humans suggests a multifactorial polygenic or oligogenic aeti ...
During gastrulation, a single epithelial cell layer, the ectoderm, generates two others: the mesoderm and the endoderm. In amniotes (birds and mammals), mesendoderm formation occurs through an axial midline structure, the primitive streak, the formation of which is preceded by massive ‘polonaise’ movements of ectoderm cells. The mechanisms controlling these processes are unknown. Here, using multi-photon time-lapse microscopy of chick (Gallus gallus) embryos, we reveal a medio-lateral cell i ...
In recent years it has been shown that bacteria contain a number of cytoskeletal structures. The bacterial cytoplasmic elements include homologs of the three major types of eukaryotic cytoskeletal proteins (actin, tubulin, and intermediate filament proteins) and a fourth group, the MinD-ParA group, that appears to be unique to bacteria. The cytoskeletal structures play important roles in cell division, cell polarity, cell shape regulation, plasmid partition, and other functions. The proteins sel ...
MANY animals with overall bilateral symmetry also exhibit some left–right asymmetries with generally invariant handedness. Therefore, the left–right embryonic axis must have a consistent polarity, whose origins and subsequent effects on development are not understood (reviewed in ref. 1). Caenorhabditis elegans exhibits such left–right asymmetries at all developmental stages. The embryonic cell lineage is asymmetric as well: although the animal is generally bilaterally symmetric, many of i ...
Platyhelminthes are widely considered to be the sister group of coelomates (Philippe, H., Chenuil, A. and Adoutte, A. (1994)Development 1994 Supplement, 15-24) and the first organisms to show bilateral symmetry and cephalization. Within this phylum, the freshwater planarians (Turbellaria, Tricladida) have been used as model systems for studying bidirectional regeneration (Slack, J. M. W. (1980) J. Theor. Biol 82, 105-140). We have been attempting to identify potential pattern-control genes invol ...
We present the largest series of mucinous carcinoma involving the skin, describing the histopathologic, immunohistochemical, electron microscopic, and cytogenetic findings. Our aim was fully to characterize the clinicopathologic spectrum and compare it with that seen in the breast. In addition, we wished to reevaluate the differential diagnostic criteria for distinguishing primary mucinous carcinomas from histologically similar neoplasms involving the skin secondarily, and study some aspects of ...
Although centrosomes contribute to spindle formation in most cell types, oocytes of many species are acentrosomal and must organize spindles in their absence. Here we investigate this process in Caenorhabditis elegans, detailing how acentrosomal spindles form and revealing mechanisms required to establish bipolarity. Using high-resolution imaging, we find that in meiosis I, microtubules initially form a "cage-like" structure inside the disassembling nuclear envelope. This structure reorganizes s ...
The zebrafish pronephros provides an excellent in vivo system to study the mechanisms of vertebrate nephron development. When and how renal progenitors in the zebrafish embryo undergo tubulogenesis to form nephrons is poorly understood, but is known to involve a mesenchymal to epithelial transition (MET) and the acquisition of polarity. Here, we determined the precise timing of these events in pronephros tubulogenesis. As the ternary polarity complex is an essential regulator of epithelial cell ...