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29
Personal correspondence
, 2014
"... Design A prospective observational study over 1 year. Setting A District General Hospital, and Child and Adolescent Mental Health Department. Patients Children aged 8–18 years living in the catchment area of a district hospital service with any type of unexplained hallucinations or illusions associa ..."
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Design A prospective observational study over 1 year. Setting A District General Hospital, and Child and Adolescent Mental Health Department. Patients Children aged 8–18 years living in the catchment area of a district hospital service with any type of unexplained hallucinations or illusions associated with or without an established diagnosis of migraine. Results The study identified nine children with a combination of migraine and a variety of hallucinations and illusions, including illusions of size, time, colour, body shape, movement and visual and auditory hallucination. An average of 10 symptoms (range 7–15) were reported. Interventions None. Main outcome measure None. Conclusions It is important to recognise these symptoms to enable appropriate history taking and diagnosis. These symptoms are common and currently seem to go unrecognised and may pose diagnostic difficulties if onset is before typical migraine headaches occur.
Molecular aspects of membrane trafficking in Paramecium
- Int. Rev. Cytol
, 2003
"... Results achieved in tile molecular biology of Paramecium have shed new light on its elaborate membrane trafficking system. Paramecium disposes not only of the standard routes (endoplasmic reticulum---+ Golgi---+ Iysosomes or secretory vesicles; endo- and phagosomes---+ Iysosomes/digesting vacuoles), ..."
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Results achieved in tile molecular biology of Paramecium have shed new light on its elaborate membrane trafficking system. Paramecium disposes not only of the standard routes (endoplasmic reticulum---+ Golgi---+ Iysosomes or secretory vesicles; endo- and phagosomes---+ Iysosomes/digesting vacuoles), but also of some unique features, e.g. and elaborate phagocytic route with the cytoproct and membrane recycling to the cytopharynx, as well as the osmoregulatory system with multiple membrane fusion sites. Exocytosis sites for trichocysts (dense-core secretory vesicles), parasomal sacs (coated pits), and terminal cisternae (early endosomes) display additional regularly arranged predetermined fusion/fission sites, which now can be discussed on a molecular basis. Considering the regular, repetitive arrangements of membrane components, availability of mutants for complementation studies, sensitivity to gene silencing, and so on, Paramecium continues to be a valuable model system for analyzing membrane interactions. This review intends to set a new baseline for ongoing work along these lines.
Novel Types of Ca 2 � Release Channels Participate in the Secretory Cycle of Paramecium Cells � †
, 2009
"... This article cites 107 articles, 42 of which can be accessed free ..."
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This article cites 107 articles, 42 of which can be accessed free
Refilling of cortical calcium stores in Paramecium cells: in situ analysis in correlation with store-operated calcium influx, Cell Calcium 34
, 2003
"... This is the first thorough study of refilling of a cortical calcium store in a secretory cell after stimulation in which we combined widely different methodologies. Stimulation of dense-core vesicle (“trichocysts”) exocytosis in Paramecium involves a Ca2+-influx” superimposed to Ca2+-release from co ..."
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This is the first thorough study of refilling of a cortical calcium store in a secretory cell after stimulation in which we combined widely different methodologies. Stimulation of dense-core vesicle (“trichocysts”) exocytosis in Paramecium involves a Ca2+-influx” superimposed to Ca2+-release from cortical stores (“alveolar sacs ” (ASs)). In quenched-flow experiments, membrane fusion frequency rose with increasing [Ca2+]o in the medium, from∼20–25 % at [Ca2+]o ≤0.25M to 100 % at [Ca2+]o between 2 and 10M, i.e. close to the range of estimated local intracellular [Ca2+] during membrane fusion. Next, we analyzed Ca2+-specific fluorochrome signals during stimulation under different conditions. Treatment with actin-reactive drugs had no effect on Ca2+-signaling. In double trigger experiments, with BAPTA in the second secretagogue application (BAPTA only for stimulation and analysis), the cortical Ca2+-signal (due solely to Ca2+ released from cortical stores) recovered with t1/2 ∼65 min. When ASs were analyzed in situ by X-ray microanalysis after different trigger times (+Ca2+o), t1/2 for store refilling was similar, ∼60 min. These values are similar to previously measured 45Ca2+-uptake by isolated ASs. In sum we find, (i) exogenous Ca2+ increases exocytosis/membrane fusion performance with EC50 = 0.7M, (ii) Ca2+-signaling in this system is not sensitive to actin-reactive drugs, and (iii) refilling of these cortical calcium stores goes on over hours and thus is much slower than expected.
One-way calcium spill-over during signal transduction in Paramecium cells: from the cell cortex into cilia, but not in the reverse direction
, 2004
"... We asked to what extent Ca2+ signals in two different domains of Paramecium cells remain separated during different stimulations. Wild-type (7S) and pawn cells (strain d4-500r, without ciliary voltage-dependent Ca2+-channels) were stimulated for trichocyst exocytosis within 80 ms by quenched-flow pr ..."
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We asked to what extent Ca2+ signals in two different domains of Paramecium cells remain separated during different stimulations. Wild-type (7S) and pawn cells (strain d4-500r, without ciliary voltage-dependent Ca2+-channels) were stimulated for trichocyst exocytosis within 80 ms by quenched-flow preparation and analysed by energy-dispersive X-ray microanalysis (EDX), paralleled by fast confocal fluorochrome analysis. We also analysed depolarisation-dependent calcium signalling during ciliary beat rerversal, also by EDX, after 80-ms stimulation in the quenched-flow mode. EDX and fluorochrome analysis enable to register total and free intracellular calcium concentrations, [Ca] and [Ca2+], respectively. After exocytosis stimulation we find by both methods that the calcium signal sweeps into the basis of cilia, not only in 7S but also in pawn cells which then also perform ciliary reversal. After depolarisation we see an increase of [Ca] along cilia selectively in 7S, but not in pawn cells. Opposite to exocytosis stimulation, during depolarisation no calcium spill-over into the nearby cytosol and no exocytosis occurs. In sum, we conclude that cilia must contain a very potent Ca2+ buffering system and that ciliary reversal induction, much more than exocytosis stimulation, involves strict microdomain regulation of Ca2+ signals.
Multigene Family Encoding 3�,5�-Cyclic-GMP-Dependent Protein
, 2005
"... In the ciliate Paramecium tetraurelia, 3�,5�-cyclic GMP (cGMP) is one of the second messengers involved in several signal transduction pathways. The enzymes for its production and degradation are well established for these cells, whereas less is known about the potential effector proteins. On the ba ..."
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In the ciliate Paramecium tetraurelia, 3�,5�-cyclic GMP (cGMP) is one of the second messengers involved in several signal transduction pathways. The enzymes for its production and degradation are well established for these cells, whereas less is known about the potential effector proteins. On the basis of a current Paramecium genome project, we have identified a multigene family with at least 35 members, all of which encode cGMPdependent protein kinases (PKGs). They can be classified into 16 subfamilies with several members each. Two of the genes, PKG1-1 and PKG2-1, were analyzed in more detail after molecular cloning. They encode monomeric enzymes of 770 and 819 amino acids, respectively, whose overall domain organization resembles that in higher eukaryotes. The enzymes contain a regulatory domain of two tandem cyclic nucleotide-binding sites flanked by an amino-terminal region for intracellular localization and a catalytic domain with highly conserved regions for ATP binding and catalysis. However, some Paramecium PKGs show a different structure. In Western blots, PKGs are detected both as cytosolic and as structure-bound forms. Immunofluorescence labeling shows enrichment in the cell cortex, notably around the dense-core secretory vesicles (trichocysts), as well as in cilia. Immunogold electron microscopy analysis reveals consistent labeling of ciliary membranes, of the membrane complex composed of cell membrane and cortical Ca 2 � stores, and of regions adjacent to ciliary basal bodies, trichocysts, and trafficking vesicles. Since PKGs (re)phosphorylate the exocytosis-sensitive
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"... Increases in the concentration of intracellular Ca2+, [Ca2+]i, govern a variety of processes in response to cell stimulation, such as exocytosis and cell contraction. A rise in intracellular Ca2+ may be due to Ca2+ influx from the outside medium or ..."
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Increases in the concentration of intracellular Ca2+, [Ca2+]i, govern a variety of processes in response to cell stimulation, such as exocytosis and cell contraction. A rise in intracellular Ca2+ may be due to Ca2+ influx from the outside medium or
unknown title
, 2002
"... cell calcium www.elsevieLcom/locate/ceca Refilling of cortical calcium stores in Paramecium cells: in situ analysis in correlation with store-operated calcium influx ..."
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cell calcium www.elsevieLcom/locate/ceca Refilling of cortical calcium stores in Paramecium cells: in situ analysis in correlation with store-operated calcium influx
My favorite cell My favorite cell-Paramecium Helmut Plattner Summary
"... A Paramecium cell has a stereotypically patterned sur-face, with regularly arranged cilia, dense-core secretory vesicles and subplasmalemmal calcium stores. Less strikingly, there is also a patterning of molecules; for instance, some ion channels are restricted to certain regions of the cell surface ..."
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A Paramecium cell has a stereotypically patterned sur-face, with regularly arranged cilia, dense-core secretory vesicles and subplasmalemmal calcium stores. Less strikingly, there is also a patterning of molecules; for instance, some ion channels are restricted to certain regions of the cell surface. This design may explain very effective and selective responses, such as that to Ca2 + upon stimulation. It enables the cell to respond to a Ca2+ signal precisely secretion (exocytosis) or by changing its ciliary activity. These responses depend on the location and/or type of signal, even though these two target structures co-exist side-by-side, and normally only limited overlap occurs between the different functions. Furthermore, the patterning of exocytotic sites and the possibility of synchronous exocytosis induction in the sub-second time range have considerably facilitated analyses, and thus led to new concepts of exocytotic membrane fusion. It has been possible to dissect com-plicated events like overlapping Ca2 + fluxes produced from external sources and from internal stores. Since molecular genetic approaches have become available for Paramecium, many different gene products have been identified only some of which are known from "higher" eUkaryotes. Although a variety of basic cellular functions are briefly addressed to demonstrate the uniqueness of this unicellular organism, this article focuses on exocy-tosis regulation. BioEssays 24:649-658, 2002. © 2002 Wiley Periodicals, Inc.
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"... Increases in the concentration of intracellular Ca2+, [Ca2+]i, govern a variety of processes in response to cell stimulation, such as exocytosis and cell contraction. A rise in intracellular Ca2+ may be due to Ca2+ influx from the outside medium or ..."
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Increases in the concentration of intracellular Ca2+, [Ca2+]i, govern a variety of processes in response to cell stimulation, such as exocytosis and cell contraction. A rise in intracellular Ca2+ may be due to Ca2+ influx from the outside medium or
