WordNet

small room in which a monk or nun lives (同)cubicle
a device that delivers an electric current as the result of a chemical reaction (同)electric cell
a room where a prisoner is kept (同)jail cell, prison cell
(biology) the basic structural and functional unit of all organisms; they may exist as independent units of life (as in monads) or may form colonies or tissues as in higher plants and animals
any small compartment; "the cells of a honeycomb"
a small unit serving as part of or as the nucleus of a larger political movement (同)cadre
parallel to or in the plane of the horizon or a base line; "a horizontal surface"
something that is oriented horizontally

PrepTutorEJDIC

(刑務所の)『独房』;(修道院の)小さい独居室 / (ミツバチの)みつ房,巣穴 / 小さい部屋 / 『細胞』 / 電池 / 花粉室 / (共産党などの)細胞
『水平線の』,地平線の;水平の,水平面の / 水平の位置;水平線(面)

Wikipedia preview

出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/10/26 02:07:03」(JST)

wiki en

Horizontal cells are the laterally interconnecting neurons having cell bodies in the inner nuclear layer of the retina of vertebrate eyes. They help integrate and regulate the input from multiple photoreceptor cells. Among their functions, horizontal cells are responsible for allowing eyes to adjust to see well under both bright and dim light conditions. Horizontal cells are inhibitory interneurons that release GABA upon depolarization

The four types of retinal neurons are bipolar cells, ganglion cells, horizontal cells, and amacrine cells.

Organization

There are three basic types of horizontal cells, designated HI, HII and HIII. The selectivity of these three horizontal cells, towards one of the three cone types, is a matter of debate. According to studies conducted by Boycott and Wassle neither HI cells nor HII cells were selective towards S,M, or L cones. By contrast, Anhelt and Kolb claim that in their observations HI cells connected to all three cone types indiscriminately, however, HII cells tended to contact S cones the most. They also identified a third type of horizontal cell, HIII, which was identical to HI but did not make contact with S cones.

The HII cells also make connections with rods, but do so far enough away from the horizontal cell's soma such that they do not interfere with the activities of the cones.

Horizontal cells span across cones and summate inputs before feeding back onto the photoreceptor cells, hyperpolarizing them. The exact mechanism by which the horizontal cells induce this hyperpolarization is uncertain, but two mechanisms are possible. In the first, hyperpolarization is proposed to be mediated synaptically by the release of GABA by horizontal cells that acts on the photoreceptor cells. In a second option, hyperpolarization occurs non-synaptically by a form of ephaptic transmission in which hemichannels on the horizontal cell dendrites modulate the extracellular potential immediately surrounding photoreceptor terminals.^[1] It is worth noting that these two mechanisms are not mutually exclusive and hyperpolarization likely occurs through the combined effects of each of them. The horizontal cells arrangement together with the on-center and off-center bipolar cells that receive input from the photoreceptors constitutes a form of lateral inhibition, increasing spatial resolution at the expense of some information on absolute intensity. The presence of highly polarized retina horizontal cells provides the eye with contrast sensitivity and an enhanced ability to discriminate differences in intensity.

There is a greater density of horizontal cells towards the central region of the retina. In cat retina it is observed that there is a density of 225 cells/mm² near the center of the retina and a density of 120 cells/mm² in the peripherals.^[2]

Horizontal cells and other retinal interneuron cells are less likely to be near neighbours of the same subtype than would occur by chance, resulting in ‘exclusion zones’ that separate them. Mosaic arrangements provide a mechanism to distribute each cell type evenly across the retina, ensuring that all parts of the visual field have access to a full set of processing elements.^[3] MEGF10 and MEGF11 transmembrane proteins have critical roles in the formation of the mosaics by horizontal cells and starburst amacrine cells in mice.^[4]

Functional properties

Horizontal cells are depolarized by the release of glutamate from photoreceptors, which happens in the absence of light. Depolarization of a horizontal cell causes it to release the inhibitory neurotransmitter GABA on an adjacent photoreceptor. GABA inhibits this photoreceptor, effectively hyperpolarizing it. Conversely, in the light a photoreceptor does not release or it releases less glutamate onto the horizontal cell, which hyperpolarizes it and prevents or lowers the release of inhibitory GABA on the adjacent photoreceptor. We therefore have the following negative feedback.

Illumination Center photoreceptor hyperpolarization horizontal cell hyperpolarization Surround photoreceptor depolarization

One hypothesis ^[5]^[6] for facilitation by the horizontal cells proceeds as follows. Assume we have 10 photoreceptors, one hyperpolarizing (H) bipolar cell, and one horizontal cell. All ten photoreceptors connect to the horizontal cell, and the middle photoreceptor () connects to the bipolar cell. The surrounding cells, which represent the outer receptive field, will be designated then we can explain an off-centre arrangement as follows. If light is shone onto the then

is activated by light and therefore hyperpolarizes
reduces its release of glutamate
Reduction of glutamate hyperpolarizes the H bipolar cell
Reduction of glutamate hyperpolarizes the horizontal cell and it reduces release of GABA
Since is still releasing glutamate, reduction in GABA is marginal

If the light is shone onto only but not then:

is activated and therefore hyperpolarizes
reduce their release of glutamate
The reduction of glutamate hyperpolarizes the horizontal cell
The horizontal cell reduces its release of GABA
The reduction of GABA generally promotes the depolarization of adjacent photoreceptors
However, because are illuminated they are strongly hyperpolarized by phototransduction - therefore a reduction in GABA is insufficient to make depolarise
But, because is already in darkness, the reduction in GABA levels is effective at causing to depolarise
releases glutamate
H Bipolar cell is depolarized

To explain diffuse light, then we consider both cases together, and as it turns out, the two effects cancel each other out, and we get little or no net effect. See http://en.wikipedia.org/wiki/Center_surround_antagonism

References

^ Sohl, G; Maxeiner, S; Willecke, K (March 2005). "Expression and functions of neuronal gap junctions". Nature Reviews Neuroscience 6: 191–200. doi:10.1038/nrn1627.
^ Wassle, H.; Riemann, H. J. (22 March 1978). "The Mosaic of Nerve Cells in the Mammalian Retina". Proceedings of the Royal Society B: Biological Sciences 200 (1141): 441–461. doi:10.1098/rspb.1978.0026.
^ Wassle, H.; Riemann, H. J. (22 March 1978). "The Mosaic of Nerve Cells in the Mammalian Retina". Proceedings of the Royal Society B: Biological Sciences 200 (1141): 441–461. doi:10.1098/rspb.1978.0026.
^ Kay, Jeremy N.; Chu, Monica W.; Sanes, Joshua R. (March 2012). "MEGF10 and MEGF11 mediate homotypic interactions required for mosaic spacing of retinal neurons". Nature 483: 465–9. doi:10.1038/nature10877. PMID 22407321.
^ Werblin, F.S.; Dowling, J.E. (1969). "Organization of the retina of the mudpuppy, Necturus maculosus. II. Intracellular recording.". J Neurophysiol. 32 (3): 339–355. PMID 4306897.
^ Werblin, F.S. (1991). "Synaptic connections, receptive fields, and patterns of activity in the tiger salamander retina.". Invest Ophthal Vis Sci. 32 (8): 459–483. PMID 2001922.

Nicholls, John G.; A. Robert Martin; Bruce G. Wallace; Paul A. Fuchs (2001). From Neuron to Brain. Boston, Massachusetts: Sinauer Associates, Inc. ISBN 0-87893-439-1.

Masland RH (2001). "The fundamental plan of the retina". Nat. Neurosci. 4 (9): 877–86. doi:10.1038/nn0901-877. PMID 11528418.

Dacey, Dennis M (1999). "Primate Retina: Cell Types, Circuits and Color Opponency". Progress in Retinal and Eye Research 18 (6): 737–763. doi:10.1016/S1350-9462(98)00013-5. PMID 10530750.

External links

Webvision: Horizontal Cell
NIF Search - Horizontal Cell via the Neuroscience Information Framework

UpToDate Contents

全文を閲覧するには購読必要です。 To read the full text you will need to subscribe.

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5. HLAハプロタイプ適合造血細胞移植 hla haploidentical hematopoietic cell transplantation

English Journal

Design and characterisation of a novel in vitro skin diffusion cell system for assessing mass casualty decontamination systems.

Matar H1, Larner J1, Kansagra S1, Atkinson KL1, Skamarauskas JT1, Amlot R2, Chilcott RP3.Author information 1Research Centre for Transdermal Drug Delivery and Toxicology, Department of Pharmacy, University of Hertfordshire, Hatfield, United Kingdom.2Microbial Risk Assessment & Behavioural Science, Emergency Response Department, Public Health England, Porton Down, Salisbury, United Kingdom.3Research Centre for Transdermal Drug Delivery and Toxicology, Department of Pharmacy, University of Hertfordshire, Hatfield, United Kingdom. Electronic address: r.chilcott@herts.ac.uk.AbstractThe efficient removal of contaminants from the outer surfaces of the body can provide an effective means of reducing adverse health effects associated with incidents involving the accidental or deliberate release of hazardous materials. Showering with water is frequently used by first responders as a rapid method of mass casualty decontamination (MCD). However, there is a paucity of data on the generic effectiveness and safety of aqueous decontamination systems. To address these issues, we have developed a new in vitro skin diffusion cell system to model the conditions of a common MCD procedure ("ladder pipe system"). The new diffusion cell design incorporates a showering nozzle, an air sampling port for measurement of vapour loss and/aerosolisation, adjustable (horizontal to vertical) skin orientation and a circulating manifold system (to maintain a specified flow rate, temperature and pressure of shower water). The dermal absorption characteristics of several simulants (Invisible Red S, curcumin and methyl salicylate) measured with the new in vitro model were in good agreement with previous in vitro and in vivo studies. Moreover, these initial studies have indicated that whilst flow rate and water temperature are important factors for MCD, the presence of clothing during showering may (under certain circumstances) cause transfer and spreading of contaminants to the skin surface.
Toxicology in vitro : an international journal published in association with BIBRA.Toxicol In Vitro.2014 Jun;28(4):492-501. doi: 10.1016/j.tiv.2014.01.001. Epub 2014 Jan 8.
The efficient removal of contaminants from the outer surfaces of the body can provide an effective means of reducing adverse health effects associated with incidents involving the accidental or deliberate release of hazardous materials. Showering with water is frequently used by first responders as
PMID 24412538

Expression profiles of calcium-dependent protein kinase genes (CDPK1-14) in Agrobacterium rhizogenes pRiA4-transformed calli of Rubia cordifolia under temperature- and salt-induced stresses.

Veremeichik GN1, Shkryl YN2, Pinkus SA1, Bulgakov VP3.Author information 1Institute of Biology and Soil Science, Far East Branch of Russian Academy of Sciences, Vladivostok 690022, Russia.2Institute of Biology and Soil Science, Far East Branch of Russian Academy of Sciences, Vladivostok 690022, Russia; Far Eastern Federal University, Vladivostok 690950, Russia. Electronic address: yn80@mail.ru.3Institute of Biology and Soil Science, Far East Branch of Russian Academy of Sciences, Vladivostok 690022, Russia; Far Eastern Federal University, Vladivostok 690950, Russia.AbstractAgrobacterium rhizogenes genetically transform plant cells naturally via horizontal gene transfer by the introduction of T-DNA from the Ri plasmid into genomic DNA to create favorable conditions for successful colonization. An intriguing feature of pRiA4-transformed cells is their recently discovered enhanced tolerance to abiotic stress stimuli and activation of antioxidant enzyme expression. The mechanism by which A. rhizogenes modulates the defense responses of transformed cells remains unclear. It has been established that calcium-dependent protein kinase (CDPK) genes mediate crosstalk of signaling pathways in plants, and these genes have been implicated in biotic and abiotic stress signaling. In this study, we identified fourteen CDPK genes from Rubia cordifolia and examined their expression in aerial plant organs as well as in non-transformed and A. rhizogenes A4-transformed calli. Expression of RcCDPK4, RcCDPK5, RcCDPK7, and RcCDPK10 was 1.2- to 3.9-fold higher in pRiA4-transformed cells than in non-transformed cells, whereas expression of RcCDPK1, RcCDPK9, RcCDPK11, and RcCDPK14 was 1.2- to 1.9-fold lower. Agrobacterium transformation substantially modified the transcriptional responses of specific RcCDPK isoforms in pRiA4-transformed cells under conditions of temperature- and salinity-induced stress. On the basis of the results, we suggest that A. rhizogenes T-DNA genes exert their diverse biological functions by altering the expression of various CDPK genes.
Journal of plant physiology.J Plant Physiol.2014 Apr 15;171(7):467-74. doi: 10.1016/j.jplph.2013.12.010. Epub 2014 Mar 4.
Agrobacterium rhizogenes genetically transform plant cells naturally via horizontal gene transfer by the introduction of T-DNA from the Ri plasmid into genomic DNA to create favorable conditions for successful colonization. An intriguing feature of pRiA4-transformed cells is their recently discovere
PMID 24655382

Viral potassium channels as a robust model system for studies of membrane-protein interaction.

Braun CJ1, Lachnit C1, Becker P1, Henkes LM2, Arrigoni C3, Kast SM2, Moroni A4, Thiel G1, Schroeder I5.Author information 1Membrane Biophysics, Technical University of Darmstadt, Schnittspahnstrasse 3, 64287 Darmstadt, Germany.2Physikalische Chemie III, Technische Universität Dortmund, Otto-Hahn-Str. 6, 44227 Dortmund, Germany.3Department of Biosciences, University of Milan, Via Celoria 26, 20133 Milano, Italy.4Department of Biosciences, University of Milan, Via Celoria 26, 20133 Milano, Italy; CNR-IBF, Via Celoria 26, 20133 Milano, Italy.5Membrane Biophysics, Technical University of Darmstadt, Schnittspahnstrasse 3, 64287 Darmstadt, Germany. Electronic address: schroeder@bio.tu-darmstadt.de.AbstractThe viral channel KcvNTS belongs to the smallest K(+) channels known so far. A monomer of a functional homotetramer contains only 82 amino acids. As a consequence of the small size the protein is almost fully submerged into the membrane. This suggests that the channel is presumably sensitive to its lipid environment. Here we perform a comparative analysis for the function of the channel protein embedded in three different membrane environments. 1. Single-channel currents of KcvNTS were recorded with the patch clamp method on the plasma membrane of HEK293 cells. 2. They were also measured after reconstitution of recombinant channel protein into classical planar lipid bilayers and 3. into horizontal bilayers derived from giant unilamellar vesicles (GUVs). The recombinant channel protein was either expressed and purified from Pichia pastoris or from a cell-free expression system; for the latter a new approach with nanolipoprotein particles was used. The data show that single-channel activity can be recorded under all experimental conditions. The main functional features of the channel like a large single-channel conductance (80pS), high open-probability (>50%) and the approximate duration of open and closed dwell times are maintained in all experimental systems. An apparent difference between the approaches was only observed with respect to the unitary conductance, which was ca. 35% lower in HEK293 cells than in the other systems. The reason for this might be explained by the fact that the channel is tagged by GFP when expressed in HEK293 cells. Collectively the data demonstrate that the small viral channel exhibits a robust function in different experimental systems. This justifies an extrapolation of functional data from these systems to the potential performance of the channel in the virus/host interaction. This article is part of a Special Issue entitled: Viral Membrane Proteins-Channels for Cellular Networking.
Biochimica et biophysica acta.Biochim Biophys Acta.2014 Apr;1838(4):1096-103. doi: 10.1016/j.bbamem.2013.06.010. Epub 2013 Jun 17.
The viral channel KcvNTS belongs to the smallest K(+) channels known so far. A monomer of a functional homotetramer contains only 82 amino acids. As a consequence of the small size the protein is almost fully submerged into the membrane. This suggests that the channel is presumably sensitive to its
PMID 23791706

Japanese Journal

キンギョ網膜水平細胞の反対色信号変換機構 (ニューロコンピューティング)

カミジニュートンリュウジ,平沢統,山田雅弘 [他]
電子情報通信学会技術研究報告 : 信学技報 111(483), 329-334, 2012-03-14
NAID 40019223449

High-resolution imaging of the retinal nerve fiber layer in normal eyes using adaptive optics scanning laser ophthalmoscopy.

Takayama Kohei,Ooto Sotaro,Hangai Masanori,Arakawa Naoko,Oshima Susumu,Shibata Naohisa,Hanebuchi Masaaki,Inoue Takashi,Yoshimura Nagahisa
PloS one 7(3), 2012-03
… Hyperreflective bundles above or below the fovea were seen in an arch from the temporal periphery on either side of a horizontal dividing line to the optic disc. … RNFL thickness obtained by optical coherence tomography correlated with the hyperreflective bundle widths on AO-SLO (P<0.001)　　　Conclusions　：AO-SLO revealed hyperreflective bundles and dark lines in the RNFL, believed to be retinal nerve fiber bundles and Müller cell septa. …
NAID 120003988392

Related Pictures

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★リンクテーブル★

リンク元	「網膜」「水平細胞」
関連記事	「horizontal」「cell」

「網膜」

Horizontal Cell
	Plan of retinal neurons.
Identifiers
NeuroLex ID	Horizontal Cell
	Anatomical terminology

　　[★]

英: retina
関: 眼、眼球

図：SP.275,

組織学

10層よりなる (SP.275)

構造	層		細胞体
脈絡膜
網膜
1	色素上皮層		色素上皮細胞	pigment epithelium cell
2	杆体錐体層	rod and cone layer
3	外境界膜
4	外顆粒層	outer nuclear layer	視細胞	photoreceptor
5	外網状層	outer plexiform layer
6	内顆粒層	inner nuclear layer	双極細胞	bipolar cell
			水平細胞	horizontal cell
			アマクリン細胞	amacrine cell
7	内網状層	inner plexiform layer
8	神経節細胞層	ganglion cell layer	神経節細胞	ganglion cell
9	神経線維層	optic nerve fiber layer
10	内境界膜