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Sample records for calcium transients delayed

  1. Transient Oxygen/Glucose Deprivation Causes a Delayed Loss of Mitochondria and Increases Spontaneous Calcium Signaling in Astrocytic Processes.

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    O'Donnell, John C; Jackson, Joshua G; Robinson, Michael B

    2016-07-06

    Recently, mitochondria have been localized to astrocytic processes where they shape Ca(2+) signaling; this relationship has not been examined in models of ischemia/reperfusion. We biolistically transfected astrocytes in rat hippocampal slice cultures to facilitate fluorescent confocal microscopy, and subjected these slices to transient oxygen/glucose deprivation (OGD) that causes delayed excitotoxic death of CA1 pyramidal neurons. This insult caused a delayed loss of mitochondria from astrocytic processes and increased colocalization of mitochondria with the autophagosome marker LC3B. The losses of neurons in area CA1 and mitochondria in astrocytic processes were blocked by ionotropic glutamate receptor (iGluR) antagonists, tetrodotoxin, ziconotide (Ca(2+) channel blocker), two inhibitors of reversed Na(+)/Ca(2+) exchange (KB-R7943, YM-244769), or two inhibitors of calcineurin (cyclosporin-A, FK506). The effects of OGD were mimicked by NMDA. The glutamate uptake inhibitor (3S)-3-[[3-[[4-(trifluoromethyl)benzoyl]amino]phenyl]methoxy]-l-aspartate increased neuronal loss after OGD or NMDA, and blocked the loss of astrocytic mitochondria. Exogenous glutamate in the presence of iGluR antagonists caused a loss of mitochondria without a decrease in neurons in area CA1. Using the genetic Ca(2+) indicator Lck-GCaMP-6S, we observed two types of Ca(2+) signals: (1) in the cytoplasm surrounding mitochondria (mitochondrially centered) and (2) traversing the space between mitochondria (extramitochondrial). The spatial spread, kinetics, and frequency of these events were different. The amplitude of both types was doubled and the spread of both types changed by ∼2-fold 24 h after OGD. Together, these data suggest that pathologic activation of glutamate transport and increased astrocytic Ca(2+) through reversed Na(+)/Ca(2+) exchange triggers mitochondrial loss and dramatic increases in Ca(2+) signaling in astrocytic processes. Astrocytes, the most abundant cell type in the brain

  2. Delayed Transient Post-Traumatic Quadriplegia

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    Khaloud Al-Shaaibi

    2015-03-01

    Full Text Available Transient neurological deficit following cervical trauma have been reported following sports injuries, and has been referred to as cervical cord neurapraxia. The so-called "whiplash injuries" following minor motor vehicle collisions usually do not produce any neurological deficit. Here we report the case of a whiplash type of injury presenting with a delayed onset neurological deficit, which was followed by rapid and complete recovery. The patient, an otherwise healthy 34-year-old male, attended the emergency department of Sultan Qaboos University Hospital following a rear-end motor vehicle collision. We present images showing degenerative disc disease causing spinal canal narrowing and mild cord compression in the patient, but no spinal instability. Differential diagnoses are also discussed.

  3. Calibrating a spatially encoded time delay for transient absorption spectroscopy

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    Wilson, Kelly S.; Wong, Cathy Y.

    2017-08-01

    A novel spectroscopy termed single shot transient absorption (SSTA) is presented that can collect a transient absorption spectrum in 6 ms by using laser pulses with tilted wavefronts to spatially encode the delay between pump and probe pulse arrival times at the sample. The transient absorption technique determines the change in sample transmission that results from sample photoexcitation, and tracks this change as a function of the time delay between the arrival of the pump pulse and the probe pulse. Typically, these time delays are generated using a retroreflecting mirror mounted on a motorized translation stage, with a measurement collected at each translation stage position. Because these measurements must be performed in series, data collection requires a significant amount of time. This limits transient absorption to the measurement of systems that are static for the duration of the experiment. SSTA overcomes this restriction by employing pump and probe pulses which are each focused into a line and tilted with respect to each other to spatially encode time delays within the sample. Here, we describe the SSTA technique and instrumentation, demonstrate the principle of this spectroscopy, and present a method for calibrating the spatially encoded time delay by autocorrelation. This instrument will broaden the scop

  4. Transient nystagmus in delayed visual maturation.

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    Bianchi, P E; Salati, R; Cavallini, A; Fazzi, E

    1998-04-01

    Two infants who presented with wide-amplitude and high-frequency nystagmus and lack of visual awareness in the first 3 months of life were studied. No ocular abnormalities were found. Neurodevelopmental examination, visual evoked potentials and electroretinograms were normal. One infant underwent MRI which resulted in normal findings. Two months later both patients showed increased visual responsiveness and a gradual reduction of the nystagmus amplitude. By 5 months of age nystagmus was no longer detectable and both infants appeared to be visually, developmentally, and neurologically normal. Follow-up at 3 years of age for subject 1 and at 11 months for subject 2 showed that both the infants maintained the normal ophthalmological and neurological assessments. We diagnosed delayed visual maturation with oculomotor involvement.

  5. Calcium signals can freely cross the nuclear envelope in hippocampal neurons: somatic calcium increases generate nuclear calcium transients

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    Bading Hilmar

    2007-07-01

    Full Text Available Abstract Background In hippocampal neurons, nuclear calcium signaling is important for learning- and neuronal survival-associated gene expression. However, it is unknown whether calcium signals generated by neuronal activity at the cell membrane and propagated to the soma can unrestrictedly cross the nuclear envelope to invade the nucleus. The nuclear envelope, which allows ion transit via the nuclear pore complex, may represent a barrier for calcium and has been suggested to insulate the nucleus from activity-induced cytoplasmic calcium transients in some cell types. Results Using laser-assisted uncaging of caged calcium compounds in defined sub-cellular domains, we show here that the nuclear compartment border does not represent a barrier for calcium signals in hippocampal neurons. Although passive diffusion of molecules between the cytosol and the nucleoplasm may be modulated through changes in conformational state of the nuclear pore complex, we found no evidence for a gating mechanism for calcium movement across the nuclear border. Conclusion Thus, the nuclear envelope does not spatially restrict calcium transients to the somatic cytosol but allows calcium signals to freely enter the cell nucleus to trigger genomic events.

  6. Calcium signals can freely cross the nuclear envelope in hippocampal neurons: somatic calcium increases generate nuclear calcium transients

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    Eder, Anja; Bading, Hilmar

    2007-01-01

    Background In hippocampal neurons, nuclear calcium signaling is important for learning- and neuronal survival-associated gene expression. However, it is unknown whether calcium signals generated by neuronal activity at the cell membrane and propagated to the soma can unrestrictedly cross the nuclear envelope to invade the nucleus. The nuclear envelope, which allows ion transit via the nuclear pore complex, may represent a barrier for calcium and has been suggested to insulate the nucleus from activity-induced cytoplasmic calcium transients in some cell types. Results Using laser-assisted uncaging of caged calcium compounds in defined sub-cellular domains, we show here that the nuclear compartment border does not represent a barrier for calcium signals in hippocampal neurons. Although passive diffusion of molecules between the cytosol and the nucleoplasm may be modulated through changes in conformational state of the nuclear pore complex, we found no evidence for a gating mechanism for calcium movement across the nuclear border. Conclusion Thus, the nuclear envelope does not spatially restrict calcium transients to the somatic cytosol but allows calcium signals to freely enter the cell nucleus to trigger genomic events. PMID:17663775

  7. Transmitter modulation of spike-evoked calcium transients in arousal related neurons

    DEFF Research Database (Denmark)

    Kohlmeier, Kristi Anne; Leonard, Christopher S

    2006-01-01

    -evoked intracellular calcium transients dampen excitability and stimulate NO production in these neurons. In this study, we investigated the action of several arousal-related neurotransmitters and the role of specific calcium channels in these LDT Ca(2+)-transients by simultaneous whole-cell recording and calcium...

  8. Stroma cell-derived factor-1α signaling enhances calcium transients and beating frequency in rat neonatal cardiomyocytes.

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    Ielham Hadad

    Full Text Available Stroma cell-derived factor-1α (SDF-1α is a cardioprotective chemokine, acting through its G-protein coupled receptor CXCR4. In experimental acute myocardial infarction, administration of SDF-1α induces an early improvement of systolic function which is difficult to explain solely by an anti-apoptotic and angiogenic effect. We wondered whether SDF-1α signaling might have direct effects on calcium transients and beating frequency.Primary rat neonatal cardiomyocytes were culture-expanded and characterized by immunofluorescence staining. Calcium sparks were studied by fluorescence microscopy after calcium loading with the Fluo-4 acetoxymethyl ester sensor. The cardiomyocyte enriched cellular suspension expressed troponin I and CXCR4 but was vimentin negative. Addition of SDF-1α in the medium increased cytoplasmic calcium release. The calcium response was completely abolished by using a neutralizing anti-CXCR4 antibody and partially suppressed and delayed by preincubation with an inositol triphosphate receptor (IP3R blocker, but not with a ryanodine receptor (RyR antagonist. Calcium fluxes induced by caffeine, a RyR agonist, were decreased by an IP3R blocker. Treatment with forskolin or SDF-1α increased cardiomyocyte beating frequency and their effects were additive. In vivo, treatment with SDF-1α increased left ventricular dP/dtmax.These results suggest that in rat neonatal cardiomyocytes, the SDF-1α/CXCR4 signaling increases calcium transients in an IP3-gated fashion leading to a positive chronotropic and inotropic effect.

  9. Delayed neuronal cell death in brainstem after transient brainstem ischemia in gerbils

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    Hakuba Nobuhiro

    2010-09-01

    Full Text Available Abstract Background Because of the lack of reproducible brainstem ischemia models in rodents, the temporal profile of ischemic lesions in the brainstem after transient brainstem ischemia has not been evaluated intensively. Previously, we produced a reproducible brainstem ischemia model of Mongolian gerbils. Here, we showed the temporal profile of ischemic lesions after transient brainstem ischemia. Results Brainstem ischemia was produced by occlusion of the bilateral vertebral arteries just before their entry into the transverse foramina of the cervical vertebrae of Mongolian gerbils. Animals were subjected to brainstem ischemia for 15 min, and then reperfused for 0 d (just after ischemia, 1 d, 3 d and 7 d (n = 4 in each group. Sham-operated animals (n = 4 were used as control. After deep anesthesia, the gerbils were perfused with fixative for immunohistochemical investigation. Ischemic lesions were detected by immunostaining for microtubule-associated protein 2 (MAP2. Just after 15-min brainstem ischemia, ischemic lesions were detected in the lateral vestibular nucleus and the ventral part of the spinal trigeminal nucleus, and these ischemic lesions disappeared one day after reperfusion in all animals examined. However, 3 days and 7 days after reperfusion, ischemic lesions appeared again and clusters of ionized calcium-binding adapter molecule-1(IBA-1-positive cells were detected in the same areas in all animals. Conclusion These results suggest that delayed neuronal cell death took place in the brainstem after transient brainstem ischemia in gerbils.

  10. Calmodulin activation by calcium transients in the postsynaptic density of dendritic spines.

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    Daniel X Keller

    2008-04-01

    Full Text Available The entry of calcium into dendritic spines can trigger a sequence of biochemical reactions that begins with the activation of calmodulin (CaM and ends with long-term changes to synaptic strengths. The degree of activation of CaM can depend on highly local elevations in the concentration of calcium and the duration of transient increases in calcium concentration. Accurate measurement of these local changes in calcium is difficult because the spaces are so small and the numbers of molecules are so low. We have therefore developed a Monte Carlo model of intracellular calcium dynamics within the spine that included calcium binding proteins, calcium transporters and ion channels activated by voltage and glutamate binding. The model reproduced optical recordings using calcium indicator dyes and showed that without the dye the free intracellular calcium concentration transient was much higher than predicted from the fluorescent signal. Excitatory postsynaptic potentials induced large, long-lasting calcium gradients across the postsynaptic density, which activated CaM. When glutamate was released at the synapse 10 ms before an action potential occurred, simulating activity patterns that strengthen hippocampal synapses, the calcium gradient and activation of CaM in the postsynaptic density were much greater than when the order was reversed, a condition that decreases synaptic strengths, suggesting a possible mechanism underlying the induction of long-term changes in synaptic strength. The spatial and temporal mechanisms for selectivity in CaM activation demonstrated here could be used in other signaling pathways.

  11. Chirped-pulse programming of optical coherent transient true-time delays.

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    Merkel, K D; Babbitt, W R

    1998-04-01

    Programming an optical coherent transient true-time delay device with two frequency-chirped pulses provides a novel means of performing broadband (> >GHz) true-time delay with a wide dynamic range of delays with fine temporal resolution. We have demonstrated true-time delays exceeding 2micros with sub-100-ps resolution. Chirped-pulse programming has the advantages over the previously proposed brief pulse programming [Opt. Lett. 21 1102 (1996)] of reduced instantaneous power requirements and the ability to control the true-time delay by frequency shifting the programming pulses.

  12. Comparative Analysis of Spontaneous and Stimulus-Evoked Calcium Transients in Proliferating and Differentiating Human Midbrain-Derived Stem Cells

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    Torben Johansen

    2017-01-01

    Full Text Available Spontaneous cytosolic calcium transients and oscillations have been reported in various tissues of nonhuman and human origin but not in human midbrain-derived stem cells. Using confocal microfluorimetry, we studied spontaneous calcium transients and calcium-regulating mechanisms in a human ventral mesencephalic stem cell line undergoing proliferation and neuronal differentiation. Spontaneous calcium transients were detected in a large fraction of both proliferating (>50% and differentiating (>55% cells. We provide evidence for the existence of intracellular calcium stores that respond to muscarinic activation of the cells, having sensitivity for ryanodine and thapsigargin possibly reflecting IP3 receptor activity and the presence of ryanodine receptors and calcium ATPase pumps. The observed calcium transient activity potentially supports the existence of a sodium-calcium antiporter and the existence of calcium influx induced by depletion of calcium stores. We conclude that the cells have developed the most important mechanisms governing cytosolic calcium homeostasis. This is the first comparative report of spontaneous calcium transients in proliferating and differentiating human midbrain-derived stem cells that provides evidence for the mechanisms that are likely to be involved. We propose that the observed spontaneous calcium transients may contribute to mechanisms involved in cell proliferation, phenotypic differentiation, and general cell maturation.

  13. Optimizing conditions for calcium phosphate mediated transient transfection

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    Ling Guo

    2017-03-01

    Conclusions: Calcium phosphate mediated transfection is the most low-cost approach to introduce recombinant DNA into culture cells. However, the utility of this procedure is limited in highly-differentiated cells. Here we describe the specific HBS-buffered saline, PH, glycerol shock, vortex strength, transfection medium, and particle concentrations conditions necessary to optimize this transfection method in highly differentiated cells.

  14. Fluorescence measurement of calcium transients in perfused rabbit heart using rhod 2.

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    Del Nido, P J; Glynn, P; Buenaventura, P; Salama, G; Koretsky, A P

    1998-02-01

    Surface fluorescence spectroscopy of the beating heart to measure cytosolic calcium has been limited by the need to use ultraviolet excitation light for many of the commonly used calcium indicators. Ultraviolet light in the heart produces a high level of background fluorescence and is highly absorbed, limiting tissue penetration. Visible wave-length fluorescence dyes such as rhod 2 are available; however, the lack of spectral shift with calcium binding precludes the use of ratio techniques to account for changes in cytosolic dye concentration. We have developed a method for in vivo quantitation of cytosolic rhod 2 concentration that in conjunction with calcium-dependent fluorescence measurements permits estimation of cytosolic calcium levels in perfused rabbit hearts. Reflective absorbance of excitation light by rhod 2 loaded into myocardium was used as an index of dye concentration and the ratio of fluorescence intensity to absorbance as a measure of cytosolic calcium concentration. Endothelial cell loading of rhod 2 was found to be minimal (calcium was measured in vitro to be 500 nM, and this value increased to 710 nM in the presence of 0.5 mM myoglobin. On the basis of this value and in vivo fluorescence measurements, cytosolic calcium concentration in the rabbit heart was found to be 229 +/- 90 nM at end diastole and 930 +/- 130 nM at peak systole, with peak fluorescence preceding peak ventricular pressure by approximately 40 ms. This technique should facilitate detailed analysis of calcium transients from the whole heart.

  15. Acetate transiently inhibits myocardial contraction by increasing mitochondrial calcium uptake.

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    Schooley, James F; Namboodiri, Aryan M A; Cox, Rachel T; Bünger, Rolf; Flagg, Thomas P

    2014-12-09

    There is a close relationship between cardiovascular disease and cardiac energy metabolism, and we have previously demonstrated that palmitate inhibits myocyte contraction by increasing Kv channel activity and decreasing the action potential duration. Glucose and long chain fatty acids are the major fuel sources supporting cardiac function; however, cardiac myocytes can utilize a variety of substrates for energy generation, and previous studies demonstrate the acetate is rapidly taken up and oxidized by the heart. In this study, we tested the effects of acetate on contractile function of isolated mouse ventricular myocytes. Acute exposure of myocytes to 10 mM sodium acetate caused a marked, but transient, decrease in systolic sarcomere shortening (1.49 ± 0.20% vs. 5.58 ± 0.49% in control), accompanied by a significant increase in diastolic sarcomere length (1.81 ± 0.01 μm vs. 1.77 ± 0.01 μm in control), with a near linear dose response in the 1-10 mM range. Unlike palmitate, acetate caused no change in action potential duration; however, acetate markedly increased mitochondrial Ca(2+) uptake. Moreover, pretreatment of cells with the mitochondrial Ca(2+) uptake blocker, Ru-360 (10 μM), markedly suppressed the effect of acetate on contraction. Lehninger and others have previously demonstrated that the anions of weak aliphatic acids such as acetate stimulate Ca(2+) uptake in isolated mitochondria. Here we show that this effect of acetate appears to extend to isolated cardiac myocytes where it transiently modulates cell contraction.

  16. Calcium signals can freely cross the nuclear envelope in hippocampal neurons: somatic calcium increases generate nuclear calcium transients

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    Eder, Anja; Bading, Hilmar

    2007-01-01

    Abstract Background In hippocampal neurons, nuclear calcium signaling is important for learning- and neuronal survival-associated gene expression. However, it is unknown whether calcium signals generated by neuronal activity at the cell membrane and propagated to the soma can unrestrictedly cross the nuclear envelope to invade the nucleus. The nuclear envelope, which allows ion transit via the nuclear pore complex, may represent a barrier for calcium and has been suggested to insulate the nuc...

  17. Impaired mitochondria and intracellular calcium transients in the salivary glands of obese rats.

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    Ittichaicharoen, Jitjiroj; Apaijai, Nattayaporn; Tanajak, Pongpan; Sa-Nguanmoo, Piangkwan; Chattipakorn, Nipon; Chattipakorn, Siriporn C

    2017-04-01

    Long-term consumption of a high-fat diet (HFD) causes not only obese-insulin resistance, but is also associated with mitochondrial dysfunction in several organs. However, the effect of obese-insulin resistance on salivary glands has not been investigated. We hypothesized that obese-insulin resistance induced by HFD impaired salivary gland function by reducing salivation, increasing inflammation, and fibrosis, as well as impairing mitochondrial function and calcium transient signaling. Male Wistar rats (200-220 g) were fed either a ND or an HFD (n = 8/group) for 16 weeks. At the end of week 16, salivary flow rates, metabolic parameters, and plasma oxidative stress were determined. Rats were then sacrificed and submandibular glands were removed to determine inflammation, fibrosis, apoptosis, mitochondrial function and dynamics, and intracellular calcium transient signaling. Long-term consumption of an HFD caused obese-insulin resistance and increased oxidative stress, fibrosis, inflammation, and apoptosis in the salivary glands. In addition, impaired mitochondrial function, as indicated by increased mitochondrial reactive oxygen species, mitochondrial membrane depolarization, and mitochondrial swelling in salivary glands and impaired intracellular calcium regulation, as indicated by a reduced intracellular calcium transient rising rate, decay rates, and amplitude of salivary acinar cells, were observed in HFD-fed rats. However, salivary flow rate and level of aquaporin 5 protein were not different between both groups. Although HFD consumption did not affect salivation, it caused obese-insulin resistance, leading to pathophysiological alteration of salivary glands, including impaired intracellular calcium transients, increased oxidative stress and inflammation, and salivary mitochondrial dysfunction.

  18. Shaker and Shal mediate transient calcium-independent potassium current in a Drosophila flight motoneuron.

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    Ryglewski, Stefanie; Duch, Carsten

    2009-12-01

    Ionic currents underlie the firing patterns, excitability, and synaptic integration of neurons. Despite complete sequence information in multiple species, our knowledge about ion channel function in central neurons remains incomplete. This study analyzes the potassium currents of an identified Drosophila flight motoneuron, MN5, in situ. MN5 exhibits four different potassium currents, two fast-activating transient ones and two sustained ones, one of each is calcium activated. Pharmacological and genetic manipulations unravel the specific contributions of Shaker and Shal to the calcium independent transient A-type potassium currents. alpha-dendrotoxin (Shaker specific) and phrixotoxin-2 (Shal specific) block different portions of the transient calcium independent A-type potassium current. Following targeted expression of a Shaker dominant negative transgene in MN5, the remaining A-type potassium current is alpha-dendrotoxin insensitive. In Shal RNAi knock down the remaining A-type potassium current is phrixotoxin-2 insensitive. Additionally, barium blocks calcium-activated potassium currents but also a large portion of phrixotoxin-2-sensitive A-type currents. Targeted knock down of Shaker or Shal channels each cause identical reduction in total potassium current amplitude as acute application of alpha-dendrotoxin or phrixotoxin-2, respectively. This shows that the knock downs do not cause upregulation of potassium channels underlying other A-type channels during development. Immunocytochemistry and targeted expression of modified GFP-tagged Shaker channels with intact targeting sequence in MN5 indicate predominant axonal localization. These data can now be used to investigate the roles of Shaker and Shal for motoneuron intrinsic properties, synaptic integration, and spiking output during behavior by targeted genetic manipulations.

  19. Exploring the Potential of Transient Receptor Potential: Troubleshooting Troublesome Calcium Thoroughfares in Biomedicine

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    Ammad Ahmad Farooqi

    2010-12-01

    Full Text Available Transient Receptor Potential-Canonical (TRPC channels are the border guards residing in the supra-molecular assembly of plasma membrane. TRPCs represent a family of channels that have dual functions of store-operated and second messenger-operated channels in a diversity of cell types. Any disruption in the spatio-temporal organization drastically influences the calcium homeostasis. This review summarizes current interpretations on the infrastructure and characteristic divalent ions regulation in molecular anomalies. A specific targeting of these channels will enable us to get a step closer to personalized medicines.

  20. Sea Urchin Spine Calcite Forms via a Transient Amorphous Calcium Carbonate Phase

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    Politi, Yael; Arad, Talmon; Klein, Eugenia; Weiner, Steve; Addadi, Lia

    2004-11-01

    The skeletons of adult echinoderms comprise large single crystals of calcite with smooth convoluted fenestrated morphologies, raising many questions about how they form. By using water etching, infrared spectroscopy, electron diffraction, and environmental scanning electron microscopy, we show that sea urchin spine regeneration proceeds via the initial deposition of amorphous calcium carbonate. Because most echinoderms produce the same type of skeletal material, they probably all use this same mechanism. Deposition of transient amorphous phases as a strategy for producing single crystals with complex morphology may have interesting implications for the development of sophisticated materials.

  1. Effects of colored noise and noise delay on a calcium oscillation system

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    Wang, Bing; Yin, Zhixiang

    2013-10-01

    As a calcium oscillations system is in steady state, the effects of colored noise and noise delay on the system is investigated using stochastic simulation methods. The results indicate that: (1) the colored noise can induce coherence bi-resonance phenomenon. (2) there exist three peaks in the R-τ0 (R is the reciprocal coefficient of variance, and τ0 is the self-correlation time of the colored noise) curves. For the same noise intensity Q=1, the Gaussian colored noise can induce calcium spikes but the white noise cannot do this. (3) the delay time can improve noise induced spikes regularity as τ0 is small, and R has a significant minimum with increasing τ as τ0 is large. (4) large values of ζ reduce noise induced spikes regularity.

  2. Visual Stimuli Evoked Action Potentials Trigger Rapidly Propagating Dendritic Calcium Transients in the Frog Optic Tectum Layer 6 Neurons.

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    Gytis Svirskis

    Full Text Available The superior colliculus in mammals or the optic tectum in amphibians is a major visual information processing center responsible for generation of orientating responses such as saccades in monkeys or prey catching avoidance behavior in frogs. The conserved structure function of the superior colliculus the optic tectum across distant species such as frogs, birds monkeys permits to draw rather general conclusions after studying a single species. We chose the frog optic tectum because we are able to perform whole-cell voltage-clamp recordings fluorescence imaging of tectal neurons while they respond to a visual stimulus. In the optic tectum of amphibians most visual information is processed by pear-shaped neurons possessing long dendritic branches, which receive the majority of synapses originating from the retinal ganglion cells. Since the first step of the retinal input integration is performed on these dendrites, it is important to know whether this integration is enhanced by active dendritic properties. We demonstrate that rapid calcium transients coinciding with the visual stimulus evoked action potentials in the somatic recordings can be readily detected up to the fine branches of these dendrites. These transients were blocked by calcium channel blockers nifedipine CdCl2 indicating that calcium entered dendrites via voltage-activated L-type calcium channels. The high speed of calcium transient propagation, >300 μm in <10 ms, is consistent with the notion that action potentials, actively propagating along dendrites, open voltage-gated L-type calcium channels causing rapid calcium concentration transients in the dendrites. We conclude that such activation by somatic action potentials of the dendritic voltage gated calcium channels in the close vicinity to the synapses formed by axons of the retinal ganglion cells may facilitate visual information processing in the principal neurons of the frog optic tectum.

  3. Psilocybin dose-dependently causes delayed, transient headaches in healthy volunteers.

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    Johnson, Matthew W; Sewell, R Andrew; Griffiths, Roland R

    2012-06-01

    Psilocybin is a well-characterized classic hallucinogen (psychedelic) with a long history of religious use by indigenous cultures, and nonmedical use in modern societies. Although psilocybin is structurally related to migraine medications, and case studies suggest that psilocybin may be efficacious in treatment of cluster headache, little is known about the relationship between psilocybin and headache. This double-blind study examined a broad range of psilocybin doses (0, 5, 10, 20, and 30 mg/70 kg) on headache in 18 healthy participants. Psilocybin frequently caused headache, the incidence, duration, and severity of which increased in a dose-dependent manner. All headaches had delayed onset, were transient, and lasted no more than a day after psilocybin administration. Possible mechanisms for these observations are discussed, and include induction of delayed headache through nitric oxide release. These data suggest that headache is an adverse event to be expected with the nonmedical use of psilocybin-containing mushrooms as well as the administration of psilocybin in human research. Headaches were neither severe nor disabling, and should not present a barrier to future psilocybin research. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  4. iPTF15eqv: Multiwavelength Exposé of a Peculiar Calcium-rich Transient

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    Milisavljevic, Dan; Patnaude, Daniel J.; Raymond, John C.; Drout, Maria R.; Margutti, Raffaella; Kamble, Atish; Chornock, Ryan; Guillochon, James; Sanders, Nathan E.; Parrent, Jerod T.; Lovisari, Lorenzo; Chilingarian, Igor V.; Challis, Peter; Kirshner, Robert P.; Penny, Matthew T.; Itagaki, Koichi; Eldridge, J. J.; Moriya, Takashi J.

    2017-09-01

    The progenitor systems of the class of “Ca-rich transients” is a key open issue in time domain astrophysics. These intriguing objects exhibit unusually strong calcium line emissions months after explosion, fall within an intermediate luminosity range, are often found at large projected distances from their host galaxies, and may play a vital role in enriching galaxies and the intergalactic medium. Here we present multiwavelength observations of iPTF15eqv in NGC 3430, which exhibits a unique combination of properties that bridge those observed in Ca-rich transients and SNe Ib/c. iPTF15eqv has among the highest [Ca II]/[O I] emission line ratios observed to date, yet is more luminous and decays more slowly than other Ca-rich transients. Optical and near-infrared photometry and spectroscopy reveal signatures consistent with the supernova explosion of a ≲ 10 {M}⊙ star that was stripped of its H-rich envelope via binary interaction. Distinct chemical abundances and ejecta kinematics suggest that the core collapse occurred through electron-capture processes. Deep limits on possible radio emission made with the Jansky Very Large Array imply a clean environment (n ≲ 0.1 cm-3) within a radius of ˜ {10}17 cm. Chandra X-ray Observatory observations rule out alternative scenarios involving the tidal disruption of a white dwarf (WD) by a black hole, for masses >100 M ⊙. Our results challenge the notion that spectroscopically classified Ca-rich transients only originate from WD progenitor systems, complicate the view that they are all associated with large ejection velocities, and indicate that their chemical abundances may vary widely between events.

  5. Effect of caffeine on intramembrane charge movement and calcium transients in cut skeletal muscle fibres of the frog.

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    Kovács, L; Szücs, G

    1983-08-01

    1. The authors have studied the effect of caffeine in subthreshold concentration (0.5 mmol l(-1) at 2-4 degrees C) on the contraction threshold, on intramembrane charge movement and calcium transients in voltage-clamped frog skeletal muscle fibres.2. The single-gap technique (Kovács & Schneider, 1978) was used for the voltage clamping of terminated segments of cut fibres. Ionic conductances were minimized by using caesium glutamate at the open end pool and tetraethylammonium sulphate and tetrodotoxin at the closed end pool.3. Myoplasmic calcium transients evoked by depolarizing pulses were recorded by measuring the changes in absorbance of the fibres at 720 nm after the intracellular application of Antipyrylazo III dye.4. The strength-duration curve for contraction threshold was shifted towards more negative membrane potentials in the presence of caffeine. Shift was more definite at shorter pulse durations than at the rheobase.5. The total amount of charge moving during the depolarizing pulses at different membrane potentials was not changed by caffeine treatment, whereas the threshold amounts of charge moved during the critical periods of the contraction threshold decreased at different voltages (by about 23%).6. In the presence of caffeine, calcium transients accompanying long (100 ms) depolarizing pulses showed increased voltage-dependent peak amplitudes, rising phases and rate coefficients referring to calcium release, but a decreased voltage-dependent re-uptake rate either during or after the pulse.7. Calcium transients evoked by depolarizing pulses along the strength-duration curve for contraction threshold gave the same peak amplitudes (ranging from 0.9 to 2.8 mumol l(-1) free myoplasmic calcium on different fibres), but membrane-potential-dependent latency times and rising phases. The rate coefficients for declining phase did not depend on the preceding pulse voltage.8. On applying caffeine, the calcium transients related to the contraction threshold also

  6. Delayed serum calcium biochemical response to successful parathyroidectomy in primary hyperparathyroidism.

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    Alabdulkarim, Yousof; Nassif, Edgard

    2010-01-01

    Parathyroidectomy is considered the standard treatment for primary hyperparathyroidism, however, though the onset of biochemical response is variable and is different from one patient to the other. To evaluate the onset of systemic response and the biochemical normalization of serum calcium levels to a successful surgery. In a retrospective fashion, we collected clinical data from 303 patients admitted to our hospital between 2005 and 2008, with a diagnosis of primary hyperparathyroidism after sestamibi localization. The pathology reports, parathyroidectomy results, the preoperative and postoperative parathormone (PTH) and serum calcium levels were reviewed. Response of each patient to the surgery was studied and all the data were analyzed to determine how fast the serum calcium levels drop. The majority of patients (72.9%, 221/303) showed a decrease in their serum calcium levels to normal values within 48 h. While in 40 patients it took 72 hours and 42 patients (13.8%) had a delayed normalization for more than 72 h. The pathology in the PH group was predominantly of a single adenoma 80.9% vs.19.1 with hyperplasia with a P of 0.03. Preoperative parathyroid hormone PTH elevation was not significantly deferent between the two groups (PH and EN) with a mean of 7.9±5.36 vs. 7.41±14.5 pmol/L respectively with a P of 0.43. The majority of patients with primary hyperparathyroidism (PHP) respond to parathyroidectomy in the form of normalization of their serum calcium levels and PTH within 48 h; however, a certain group of patients will need more than 3 days.

  7. The roles of calcium signaling and ERK1/2 phosphorylation in a Pax6+/- mouse model of epithelial wound-healing delay

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    McCaig Colin D

    2006-08-01

    Full Text Available Abstract Background Congenital aniridia caused by heterozygousity at the PAX6 locus is associated with ocular surface disease including keratopathy. It is not clear whether the keratopathy is a direct result of reduced PAX6 gene dosage in the cornea itself, or due to recurrent corneal trauma secondary to defects such as dry eye caused by loss of PAX6 in other tissues. We investigated the hypothesis that reducing Pax6 gene dosage leads to corneal wound-healing defects. and assayed the immediate molecular responses to wounding in wild-type and mutant corneal epithelial cells. Results Pax6+/- mouse corneal epithelia exhibited a 2-hour delay in their response to wounding, but subsequently the cells migrated normally to repair the wound. Both Pax6+/+ and Pax6+/- epithelia activated immediate wound-induced waves of intracellular calcium signaling. However, the intensity and speed of propagation of the calcium wave, mediated by release from intracellular stores, was reduced in Pax6+/- cells. Initiation and propagation of the calcium wave could be largely decoupled, and both phases of the calcium wave responses were required for wound healing. Wounded cells phosphorylated the extracellular signal-related kinases 1/2 (phospho-ERK1/2. ERK1/2 activation was shown to be required for rapid initiation of wound healing, but had only a minor effect on the rate of cell migration in a healing epithelial sheet. Addition of exogenous epidermal growth factor (EGF to wounded Pax6+/- cells restored the calcium wave, increased ERK1/2 activation and restored the immediate healing response to wild-type levels. Conclusion The study links Pax6 deficiency to a previously overlooked wound-healing delay. It demonstrates that defective calcium signaling in Pax6+/- cells underlies this delay, and shows that it can be pharmacologically corrected. ERK1/2 phosphorylation is required for the rapid initiation of wound healing. A model is presented whereby minor abrasions, which are

  8. Sources of variability in cytosolic calcium transients triggered by stimulation of homogeneous uro-epithelial cell monolayers.

    Science.gov (United States)

    Appleby, Peter A; Shabir, Saqib; Southgate, Jennifer; Walker, Dawn

    2015-04-06

    Epithelial tissue structure is the emergent outcome of the interactions between large numbers of individual cells. Experimental cell biology offers an important tool to unravel these complex interactions, but current methods of analysis tend to be limited to mean field approaches or representation by selected subsets of cells. This may result in bias towards cells that respond in a particular way and/or neglect local, context-specific cell responses. Here, an automated algorithm was applied to examine in detail the individual calcium transients evoked in genetically homogeneous, but asynchronous populations of cultured non-immortalized normal human urothelial cells when subjected to either the global application of an external agonist or a localized scratch wound. The recorded calcium transients were classified automatically according to a set of defined metrics and distinct sub-populations of cells that responded in qualitatively different ways were observed. The nature of this variability in the homogeneous cell population was apportioned to two sources: intrinsic variation in individual cell responses and extrinsic variability due to context-specific factors of the environment, such as spatial heterogeneity. Statistically significant variation in the features of the calcium transients evoked by scratch wounding according to proximity to the wound edge was identified. The manifestation of distinct sub-populations of cells is considered central to the coordination of population-level response resulting in wound closure.

  9. Episodic, transient systemic acidosis delays evolution of the malignant phenotype: Possible mechanism for cancer prevention by increased physical activity

    Directory of Open Access Journals (Sweden)

    Maini Philip K

    2010-04-01

    Full Text Available Abstract Background The transition from premalignant to invasive tumour growth is a prolonged multistep process governed by phenotypic adaptation to changing microenvironmental selection pressures. Cancer prevention strategies are required to interrupt or delay somatic evolution of the malignant invasive phenotype. Empirical studies have consistently demonstrated that increased physical activity is highly effective in reducing the risk of breast cancer but the mechanism is unknown. Results Here we propose the hypothesis that exercise-induced transient systemic acidosis will alter the in situ tumour microenvironment and delay tumour adaptation to regional hypoxia and acidosis in the later stages of carcinogenesis. We test this hypothesis using a hybrid cellular automaton approach. This model has been previously applied to somatic evolution on epithelial surfaces and demonstrated three phases of somatic evolution, with cancer cells escaping in turn from the constraints of limited space, nutrient supply and waste removal. In this paper we extend the model to test our hypothesis that transient systemic acidosis is sufficient to arrest, or at least delay, transition from in situ to invasive cancer. Conclusions Model simulations demonstrate that repeated episodes of transient systemic acidosis will interrupt critical evolutionary steps in the later stages of carcinogenesis resulting in substantial delay in the evolution to the invasive phenotype. Our results suggest transient systemic acidosis may mediate the observed reduction in cancer risk associated with increased physical activity. Reviewers This article was reviewed by Natalia Komarova (nominated by Marek Kimmel, Heiko Enderling (nominated by Marek Kimmel, Mark Little (nominated by Marek Kimmel and Yang Kuang.

  10. Calcium transients during early development in single starfish (Asterias forbesi) oocytes

    Energy Technology Data Exchange (ETDEWEB)

    Eisen, A.; Reynolds, G.T.

    1984-11-01

    Maturation and fertilization of the starfish oocyte are putative calcium-dependent events. The authors have investigated the spatial distribution and temporal dynamics of this calcium dependence in single oocytes of Asterias forbesi. They used the calcium photoprotein, aequorin, in conjunction with a microscope-photomultiplier and microscope-image intensifier. Surprisingly, in contrast to earlier work with Marasthenias glacialis, there is no detectable increase in intracellular-free calcium in the oocyte of A. forbesi in response to the maturation hormone 1-methyl adenine. During fertilization of the same, matured, A. forbesi oocyte there is a large increase in intracellular-free calcium. The calcium concentration increases to approx.1 ..mu..M at the point of insemination and the region of elevated free calcium expands across the oocyte in approx.20 s (17-19/sup 0/C). After the entire oocyte reaches an elevated concentration of free calcium, the concentration decreases uniformly throughout the oocyte over the next several minutes.

  11. Estradiol coupling to human monocyte nitric oxide release is dependent on intracellular calcium transients: evidence for an estrogen surface receptor.

    Science.gov (United States)

    Stefano, G B; Prevot, V; Beauvillain, J C; Fimiani, C; Welters, I; Cadet, P; Breton, C; Pestel, J; Salzet, M; Bilfinger, T V

    1999-10-01

    We tested the hypothesis that estrogen acutely stimulates constitutive NO synthase (cNOS) activity in human peripheral monocytes by acting on an estrogen surface receptor. NO release was measured in real time with an amperometric probe. 17beta-estradiol exposure to monocytes stimulated NO release within seconds in a concentration-dependent manner, whereas 17alpha-estradiol had no effect. 17beta-estradiol conjugated to BSA (E2-BSA) also stimulated NO release, suggesting mediation by a membrane surface receptor. Tamoxifen, an estrogen receptor inhibitor, antagonized the action of both 17beta-estradiol and E2-BSA, whereas ICI 182,780, a selective inhibitor of the nuclear estrogen receptor, had no effect. We further showed, using a dual emission microfluorometry in a calcium-free medium, that the 17beta-estradiol-stimulated release of monocyte NO was dependent on the initial stimulation of intracellular calcium transients in a tamoxifen-sensitive process. Leeching out the intracellular calcium stores abolished the effect of 17beta-estradiol on NO release. RT-PCR analysis of RNA obtained from the cells revealed a strong estrogen receptor-alpha amplification signal and a weak beta signal. Taken together, a physiological dose of estrogen acutely stimulates NO release from human monocytes via the activation of an estrogen surface receptor that is coupled to increases in intracellular calcium.

  12. Emerin plays a crucial role in nuclear invagination and in the nuclear calcium transient

    Science.gov (United States)

    Shimojima, Masaya; Yuasa, Shinsuke; Motoda, Chikaaki; Yozu, Gakuto; Nagai, Toshihiro; Ito, Shogo; Lachmann, Mark; Kashimura, Shin; Takei, Makoto; Kusumoto, Dai; Kunitomi, Akira; Hayashiji, Nozomi; Seki, Tomohisa; Tohyama, Shugo; Hashimoto, Hisayuki; Kodaira, Masaki; Egashira, Toru; Hayashi, Kenshi; Nakanishi, Chiaki; Sakata, Kenji; Yamagishi, Masakazu; Fukuda, Keiichi

    2017-01-01

    Alteration of the nuclear Ca2+ transient is an early event in cardiac remodeling. Regulation of the nuclear Ca2+ transient is partly independent of the cytosolic Ca2+ transient in cardiomyocytes. One nuclear membrane protein, emerin, is encoded by EMD, and an EMD mutation causes Emery-Dreifuss muscular dystrophy (EDMD). It remains unclear whether emerin is involved in nuclear Ca2+ homeostasis. The aim of this study is to elucidate the role of emerin in rat cardiomyocytes by means of hypertrophic stimuli and in EDMD induced pluripotent stem (iPS) cell-derived cardiomyocytes in terms of nuclear structure and the Ca2+ transient. The cardiac hypertrophic stimuli increased the nuclear area, decreased nuclear invagination, and increased the half-decay time of the nuclear Ca2+ transient in cardiomyocytes. Emd knockdown cardiomyocytes showed similar properties after hypertrophic stimuli. The EDMD-iPS cell-derived cardiomyocytes showed increased nuclear area, decreased nuclear invagination, and increased half-decay time of the nuclear Ca2+ transient. An autopsied heart from a patient with EDMD also showed increased nuclear area and decreased nuclear invagination. These data suggest that Emerin plays a crucial role in nuclear structure and in the nuclear Ca2+ transient. Thus, emerin and the nuclear Ca2+ transient are possible therapeutic targets in heart failure and EDMD. PMID:28290476

  13. Psoriasis is characterized by deficient negative immune regulation compared to transient delayed-type hypersensitivity reactions

    National Research Council Canada - National Science Library

    Gulati, Nicholas; Suárez-Fariñas, Mayte; Correa da Rosa, Joel; Krueger, James G

    2015-01-01

    Diphencyprone (DPCP) is a hapten that causes delayed-type hypersensitivity (DTH) reactions in human skin, and is used as a topical therapeutic for alopecia areata, warts, and cutaneous melanoma metastases...

  14. Calcium

    Science.gov (United States)

    ... Turn to calcium-fortified (or "calcium-set") tofu, soy milk, tempeh, soy yogurt, and cooked soybeans (edamame). Calcium-fortified foods. Look for calcium-fortified orange juice, soy or rice milk, breads, and cereal. Beans. You can get decent ...

  15. Regulation of developing myelin sheath elongation by oligodendrocyte calcium transients in vivo.

    Science.gov (United States)

    Krasnow, Anna M; Ford, Marc C; Valdivia, Leonardo E; Wilson, Stephen W; Attwell, David

    2018-01-01

    How action potentials regulate myelination by oligodendrocytes is uncertain. We show that neuronal activity raises [Ca 2+ ] i in developing oligodendrocytes in vivo and that myelin sheath elongation is promoted by a high frequency of [Ca 2+ ] i transients and prevented by [Ca 2+ ] i buffering. Sheath elongation occurs ~1 h after [Ca 2+ ] i elevation. Sheath shortening is associated with a low frequency of [Ca 2+ ] i transients but with longer duration [Ca 2+ ] i bursts. Thus, [Ca 2+ ] i controls myelin sheath development.

  16. NMDAR-mediated calcium transients elicited by glutamate co-release at developing inhibitory synapses

    Directory of Open Access Journals (Sweden)

    Abigail Kalmbach

    2010-07-01

    Full Text Available Before hearing onset, the topographic organization of the inhibitory sound localization pathway from the medial nucleus of the trapezoid body (MNTB to the lateral superior olive (LSO is refined by means of synaptic silencing and strengthening. During this refinement period MNTB-LSO synapses not only release GABA and glycine but also release glutamate. This co-released glutamate can elicit postsynaptic currents that are predominantly mediated by NMDA receptors (NMDARs. To gain a better understanding of how glutamate contributes to synaptic signaling at developing MNTB-LSO inhibitory synapse, we investigated to what degree and under what conditions NMDARs contribute to postsynaptic calcium responses. Our results demonstrate that MNTB-LSO synapses can elicit compartmentalized calcium responses along aspiny LSO dendrites. These responses are significantly attenuated by the NMDARs antagonist APV. APV, however, has no effect on somatically recorded electrical postsynaptic responses, indicating little, if any, contribution of NMDARs to spike generation. Small NMDAR-mediated calcium responses were also observed under physiological levels of extracellular magnesium concentrations indicating that MNTB-LSO synapses activate magnesium sensitive NMDAR on immature LSO dendrites. In Fura-2 AM loaded neurons, blocking GABAA and glycine receptors decreased NMDAR contribution to somatic calcium responses suggesting that GABA and glycine, perhaps by shunting backpropagating action potentials, decrease the level of NMDAR activation under strong stimulus conditions.

  17. Calcium regulation by temperature-sensitive transient receptor potential channels in human uveal melanoma cells.

    Science.gov (United States)

    Mergler, Stefan; Derckx, Raissa; Reinach, Peter S; Garreis, Fabian; Böhm, Arina; Schmelzer, Lisa; Skosyrski, Sergej; Ramesh, Niraja; Abdelmessih, Suzette; Polat, Onur Kerem; Khajavi, Noushafarin; Riechardt, Aline Isabel

    2014-01-01

    Uveal melanoma (UM) is both the most common and fatal intraocular cancer among adults worldwide. As with all types of neoplasia, changes in Ca(2+) channel regulation can contribute to the onset and progression of this pathological condition. Transient receptor potential channels (TRPs) and cannabinoid receptor type 1 (CB1) are two different types of Ca(2+) permeation pathways that can be dysregulated during neoplasia. We determined in malignant human UM and healthy uvea and four different UM cell lines whether there is gene and functional expression of TRP subtypes and CB1 since they could serve as drug targets to either prevent or inhibit initiation and progression of UM. RT-PCR, Ca(2+) transients, immunohistochemistry and planar patch-clamp analysis probed for their gene expression and functional activity, respectively. In UM cells, TRPV1 and TRPM8 gene expression was identified. Capsaicin (CAP), menthol or icilin induced Ca(2+) transients as well as changes in ion current behavior characteristic of TRPV1 and TRPM8 expression. Such effects were blocked with either La(3+), capsazepine (CPZ) or BCTC. TRPA1 and CB1 are highly expressed in human uvea, but TRPA1 is not expressed in all UM cell lines. In UM cells, the CB1 agonist, WIN 55,212-2, induced Ca(2+) transients, which were suppressed by La(3+) and CPZ whereas CAP-induced Ca(2+) transients could also be suppressed by CB1 activation. Identification of functional TRPV1, TRPM8, TRPA1 and CB1 expression in these tissues may provide novel drug targets for treatment of this aggressive neoplastic disease. © 2013.

  18. Controlling pulse delay by light and low magnetic fields: slow light in emerald induced by transient spectral hole-burning.

    Science.gov (United States)

    Rajan, Rajitha Papukutty; Riesen, Hans; Rebane, Aleksander

    2013-11-15

    Slow light based on transient spectral hole-burning is reported for emerald, Be(3)Al(2)Si(6)O(18):Cr(3+). Experiments were conducted in π polarization on the R(1)(± 3/2) line (E2 ← A(2)4) at 2.2 K in zero field and low magnetic fields B||c. The hole width was strongly dependent on B||c, and this allowed us to smoothly tune the pulse delay from 40 to 154 ns between zero field and B||c = 15.2 mT. The latter corresponds to a group velocity of 16 km/s. Slow light in conjunction with a linear filter theory can be used as a powerful and accurate technique in time-resolved spectroscopy, e.g., to determine spectral hole-widths as a function of time.

  19. Calcium-dependent expression of transient receptor potential canonical type 3 channels in patients with chronic kidney disease

    DEFF Research Database (Denmark)

    Liu, Ying; Krueger, Katharina; Hovsepian, Anahit

    2011-01-01

    It is unknown whether extracellular calcium may regulate the expression of transient receptor potential canonical type 3 (TRPC3) channels in patients with chronic kidney disease. Using quantitative in-cell Western assay we compared the expression of TRPC3 channel protein in monocytes from 20...... patients with chronic kidney disease and 19 age- and sex-matched healthy control subjects. TRPC3 channels were identified by immunoblotting using specific antibodies and TRPC3 protein was further confirmed by mass spectrometry. We observed a significant increase of TRPC3 channel protein expression...... in patients with chronic kidney disease compared to healthy control subjects (normalized expression, 0.42±0.06 vs. 0.19±0.03; p...

  20. Delayed electron relaxation in CdTe nanorods studied by spectral analysis of the ultrafast transient absorption

    Energy Technology Data Exchange (ETDEWEB)

    Kriegel, I., E-mail: ilka.kriegel@iit.it [Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy); Scotognella, F. [Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy); CNST of IIT@POLIMI, Via Pascoli 70/3, 20133 Milano (Italy); Soavi, G. [Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy); Brescia, R. [Department of Nanochemistry, Istituto Italiano di Tecnologia (IIT), via Morego 30, 16163 Genova (Italy); Rodríguez-Fernández, J.; Feldmann, J. [Photonics and Optoelectronics Group, Department of Physics and CeNS, Ludwig-Maximilians-Universität München, Amalienstr. 54, 80799 Munich (Germany); Nanosystems Initiative Munich (NIM), Schellingstr. 4, 80799 Munich (Germany); Lanzani, G., E-mail: guglielmo.lanzani@iit.it [Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy); CNST of IIT@POLIMI, Via Pascoli 70/3, 20133 Milano (Italy); Tassone, F. [CNST of IIT@POLIMI, Via Pascoli 70/3, 20133 Milano (Italy)

    2016-06-01

    Highlights: • We study the photophysics of CdTe nanorods by ultrafast absorption spectroscopy. • We fit photobleaching and photoinduced absorption features at all time delays. • Dynamics are extracted from superpositions of bleaches (Gaussians) and derivatives. • Fast non-radiative recombination and slower hole trapping processes are extracted. • A potential approach to unveil ultrafast non-radiative recombination processes. - Abstract: In transient absorption (TA) spectra, the bleach features originating from state filling are overlapped by their energy-shifted derivatives, arising from excited state energy level shifts. This makes the direct extraction of carrier dynamics from a single-wavelength time-trace misleading. Fitting TA spectra in time, as Gaussian functions and their derivative-like shifted Gaussians, allows to individually extract the real dynamics of both photobleached transitions, and their energy shifts. In CdTe nanorods (NRs) we found a delayed heating of holes due to the release of the large excess energy in the electron relaxation process. The slow hole-trapping process is consistent with a high number of surface trap states in these model NRs. Our results show that only a correct disentanglement of bleaching and energy shift contributions provides a reliable framework to extract the underlying carrier relaxation dynamics, including trapping, non-radiative recombination, and eventually carrier multiplication.

  1. High glucose enhances transient receptor potential channel canonical type 6-dependent calcium influx in human platelets via phosphatidylinositol 3-kinase-dependent pathway

    DEFF Research Database (Denmark)

    Liu, Daoyan; Maier, Alexandra; Scholze, Alexandra

    2008-01-01

    Transient receptor potential canonical type 6 (TRPC6) channels mediating 1-oleoyl-2-acetyl-sn-glycerol (OAG)-induced calcium entry have been identified on human platelets. In the present study we tested the hypothesis that hyperglycemia increases the expression of TRPC6 channels....

  2. Calcium

    Science.gov (United States)

    ... and blood vessels contract and expand, to secrete hormones and enzymes and to send messages through the nervous system. It is important to get plenty of calcium in the foods you eat. Foods rich in calcium include Dairy products such as milk, cheese, and yogurt Leafy, green vegetables Fish with ...

  3. Nimodipine, a calcium channel blocker, delays the spontaneous LH surge in women with regular menstrual cycles: a prospective pilot study.

    Science.gov (United States)

    Nayot, Dan; Klachook, Shany; Casper, Robert F

    2013-02-07

    Currently GnRH analogue injections are used to prevent premature LH surges in women undergoing assisted reproductive technology. This was a pilot study to determine the safety and effectiveness of nimodipine, an oral calcium channel blocker, to delay the mid-cycle spontaneous LH surge in women with regular menstrual cycles. Eight women with regular menstrual cycles self-monitored three consecutive cycles for the day of an LH surge by daily urine assay. The first and third cycles were observatory. In the second cycle, subjects took nimodipine 60 mg by mouth three times daily for four days, starting two days prior to the expected LH surge day based on cycle one. The LH surge day in cycle 2 (nimodipine) was significantly delayed in comparison to both observatory cycle 1 (15.5+/-3.4 vs 14.0+/-2.8 days; p=0.033) and cycle 3 (15.1+/-3.5 vs 13.1+/-2.4 days; p=0.044). There was no difference in the LH surge day between the two observatory cycles (13.4+/-2.4 vs 13.1+/-2.4 days; p=0.457). Three patients experienced a mild headache. There was a statistically significant delay in the spontaneous LH surge day in the treatment cycle in comparison to both observatory cycles. Nimopidine should be further investigated as an oral alternative to delay a spontaneous LH surge.

  4. Phase transitions and transient liquid-phase sintering in calcium-substituted lanthanum chromite

    Energy Technology Data Exchange (ETDEWEB)

    Chick, L.A.; Liu, J.; Stevenson, J.W.; Armstrong, T.R.; McCready, D.E.; Maupin, G.D.; Coffey, G.W.; Coyle, C.A. [Pacific Northwest National Lab., Richland, WA (United States). Materials and Chemical Sciences Dept.

    1997-08-01

    This paper investigates sintering and phase transitions of La{sub 0.7}Ca{sub x}CrO{sub 3} (0.25 {le} x {le} 0.35), a material useful as electrical interconnections in solid oxide fuel cells. Heating of the quenched, metastable single-phase chromite resulted in exsolution of CaCrO{sub 4} due to Ca solubility limitations below 1,200 C. A transient liquid phase formed between 850 and 1,000 C as the CaCrO{sub 4} melted, causing partial densification in materials having 0.25 < x < 0.30. A slight increase in Ca content induced an additional liquid-phase sintering event, likely due to melting of Ca{sub 3}(CrO{sub 4}){sub 2}, which facilitated near-complete densification by 1,250 C. After enhancing sintering, the secondary phases redissolved into the chromite.

  5. Anti-Epileptic Drugs Delay Age-Related Loss of Spiral Ganglion Neurons via T-type Calcium Channel

    Science.gov (United States)

    Lei, Debin; Gao, Xia; Perez, Philip; Ohlemiller, Kevin K; Chen, Chien-Chang; Campbell, Kevin P.; Hood, Aizhen Yang; Bao, Jianxin

    2011-01-01

    Loss of spiral ganglion neurons is a major cause of age-related hearing loss (presbycusis). Despite being the third most prevalent condition afflicting elderly persons, there are no known medications to prevent presbycusis. Because calcium signaling has long been implicated in age-related neuronal death, we investigated T-type calcium channels. This family is comprised of three members (Cav3.1, Cav3.2, and Cav3.3), based on their respective main pore-forming alpha subunits: α1G, α1H, and α1I. In the present study, we report a significant delay of age-related loss of cochlear function and preservation of spiral ganglion neurons in α1H null and heterozygous mice, clearly demonstrating an important role for Cav3.2 in age-related neuronal loss. Furthermore, we show that anticonvulsant drugs from a family of T-type calcium channel blockers can significantly preserve spiral ganglion neurons during aging. To our knowledge, this is the first report of drugs capable of diminishing age-related loss of spiral ganglion neurons. PMID:21640179

  6. Calcium

    Science.gov (United States)

    ... from dietary supplements are linked to a greater risk of kidney stones, especially among older adults. But calcium from foods does not appear to cause kidney stones. For most people, other factors (such as not drinking enough fluids) probably have ...

  7. Transient giant R-wave, right axis deviation, and intraventricular conduction delay during exercise treadmill testing: a case report.

    Science.gov (United States)

    Jim, Man-Hong; Siu, Chung-Wah; Lee, Stephen Wai-Luen; Lam, Linda; Chan, Raymond Hon-Wah

    2004-01-01

    A 53 year old man complained of chest pain during an exercise treadmill test. Electrocardiogram revealed transient giant R-wave, right-axis deviation, intraventricular conduction delay, and ST-segment elevation in the inferolateral leads. Subsequent coronary angiography showed an 80% lesion in mid part of a nondominant left circumflex artery, whereas the other coronary arteries had mild atherosclerosis only. Percutaneous coronary intervention and stenting was performed on the left circumflex artery lesion. A follow-up exercise thallium scan 3 months later still showed an intermediate-sized, mild reversible perfusion defect in the inferior and lateral wall but the giant R-wave ECG pattern was not inducible anymore. Restudy coronary angiography showed no in-stent restenosis, but there was disease progression in the midpart of the right coronary artery. The initial electrocardiographic pattern is typical of the "giant R-wave syndrome." Severe coronary spasm superimposed on the underlying mild atherosclerotic lesion of the right coronary artery is hypothesized to be the cause of the initial event. Ad hoc direct stenting was performed on the right coronary artery lesion. The patient remained symptom-free with a normal thallium scan 9 months later.

  8. Delayed Serum Calcium Biochemical Response to Successful Parathyroidectomy in Primary Hyperparathyroidism

    OpenAIRE

    Alabdulkarim, Yousof; Nassif, Edgard

    2010-01-01

    Background: Parathyroidectomy is considered the standard treatment for primary hyperparathyroidism, however, though the onset of biochemical response is variable and is different from one patient to the other. Aim: To evaluate the onset of systemic response and the biochemical normalization of serum calcium levels to a successful surgery. Patients and Methods: In a retrospective fashion, we collected clinical data from 303 patients admitted to our hospital between 2005 and 2008, with a diagno...

  9. Nimodipine, a calcium channel blocker, delays the spontaneous LH surge in women with regular menstrual cycles: a prospective pilot study

    Science.gov (United States)

    2013-01-01

    Background Currently GnRH analogue injections are used to prevent premature LH surges in women undergoing assisted reproductive technology. This was a pilot study to determine the safety and effectiveness of nimodipine, an oral calcium channel blocker, to delay the mid-cycle spontaneous LH surge in women with regular menstrual cycles. Methods Eight women with regular menstrual cycles self-monitored three consecutive cycles for the day of an LH surge by daily urine assay. The first and third cycles were observatory. In the second cycle, subjects took nimodipine 60 mg by mouth three times daily for four days, starting two days prior to the expected LH surge day based on cycle one. Results The LH surge day in cycle 2 (nimodipine) was significantly delayed in comparison to both observatory cycle 1 (15.5+/−3.4 vs 14.0+/−2.8 days; p = 0.033) and cycle 3 (15.1+/−3.5 vs 13.1+/−2.4 days; p = 0.044). There was no difference in the LH surge day between the two observatory cycles (13.4+/−2.4 vs 13.1+/−2.4 days; p = 0.457). Three patients experienced a mild headache. Conclusions There was a statistically significant delay in the spontaneous LH surge day in the treatment cycle in comparison to both observatory cycles. Nimopidine should be further investigated as an oral alternative to delay a spontaneous LH surge. PMID:23391256

  10. Nimodipine, a calcium channel blocker, delays the spontaneous LH surge in women with regular menstrual cycles: a prospective pilot study

    Directory of Open Access Journals (Sweden)

    Nayot Dan

    2013-02-01

    Full Text Available Abstract Background Currently GnRH analogue injections are used to prevent premature LH surges in women undergoing assisted reproductive technology. This was a pilot study to determine the safety and effectiveness of nimodipine, an oral calcium channel blocker, to delay the mid-cycle spontaneous LH surge in women with regular menstrual cycles. Methods Eight women with regular menstrual cycles self-monitored three consecutive cycles for the day of an LH surge by daily urine assay. The first and third cycles were observatory. In the second cycle, subjects took nimodipine 60 mg by mouth three times daily for four days, starting two days prior to the expected LH surge day based on cycle one. Results The LH surge day in cycle 2 (nimodipine was significantly delayed in comparison to both observatory cycle 1 (15.5+/−3.4 vs 14.0+/−2.8 days; p = 0.033 and cycle 3 (15.1+/−3.5 vs 13.1+/−2.4 days; p = 0.044. There was no difference in the LH surge day between the two observatory cycles (13.4+/−2.4 vs 13.1+/−2.4 days; p = 0.457. Three patients experienced a mild headache. Conclusions There was a statistically significant delay in the spontaneous LH surge day in the treatment cycle in comparison to both observatory cycles. Nimopidine should be further investigated as an oral alternative to delay a spontaneous LH surge.

  11. An integrated platform for simultaneous multi-well field potential recording and Fura-2-based calcium transient ratiometry in human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes.

    Science.gov (United States)

    Rast, Georg; Weber, Jürgen; Disch, Christoph; Schuck, Elmar; Ittrich, Carina; Guth, Brian D

    2015-01-01

    Human induced pluripotent stem cell-derived cardiomyocytes are available from various sources and they are being evaluated for safety testing. Several platforms are available offering different assay principles and read-out parameters: patch-clamp and field potential recording, imaging or photometry, impedance measurement, and recording of contractile force. Routine use will establish which assay principle and which parameters best serve the intended purpose. We introduce a combination of field potential recording and calcium ratiometry from spontaneously beating cardiomyocytes as a novel assay providing a complementary read-out parameter set. Field potential recording is performed using a commercial multi-well multi-electrode array platform. Calcium ratiometry is performed using a fiber optic illumination and silicon avalanche photodetectors. Data condensation and statistical analysis are designed to enable statistical inference of differences and equivalence with regard to a solvent control. Simultaneous recording of field potentials and calcium transients from spontaneously beating monolayers was done in a nine-well format. Calcium channel blockers (e.g. nifedipine) and a blocker of calcium store release (ryanodine) can be recognized and discriminated based on the calcium transient signal. An agonist of L-type calcium channels, FPL 64176, increased and prolonged the calcium transient, whereas BAY K 8644, another L-type calcium channel agonist, had no effect. Both FPL 64176 and various calcium channel antagonists have chronotropic effects, which can be discriminated from typical "chronotropic" compounds, like (±)isoprenaline (positive) and arecaidine propargyl ester (negative), based on their effects on the calcium transient. Despite technical limitations in temporal resolution and exact matching of composite calcium transient with the field potential of a subset of cells, the combined recording platform enables a refined interpretation of the field potential

  12. Pharmacological Characterization of the Mechanisms Involved in Delayed Calcium Deregulation in SH-SY5Y Cells Challenged with Methadone

    Science.gov (United States)

    Perez-Alvarez, Sergio; Solesio, Maria E.; Cuenca-Lopez, Maria D.; Melero-Fernández de Mera, Raquel M.; Villalobos, Carlos; Kmita, Hanna; Galindo, Maria F.; Jordán, Joaquin

    2012-01-01

    Previously, we have shown that SH-SY5Y cells exposed to high concentrations of methadone died due to a necrotic-like cell death mechanism related to delayed calcium deregulation (DCD). In this study, we show that, in terms of their Ca2+ responses to 0.5 mM methadone, SH-SY5Y cells can be pooled into four different groups. In a broad pharmacological survey, the relevance of different Ca2+-related mechanisms on methadone-induced DCD was investigated including extracellular calcium, L-type Ca2+ channels, μ-opioid receptor, mitochondrial inner membrane potential, mitochondrial ATP synthesis, mitochondrial Ca2+/2Na+-exchanger, reactive oxygen species, and mitochondrial permeability transition. Only those compounds targeting mitochondria such as oligomycin, FCCP, CGP 37157, and cyclosporine A were able to amend methadone-induced Ca2+ dyshomeostasis suggesting that methadone induces DCD by modulating the ability of mitochondria to handle Ca2+. Consistently, mitochondria became dramatically shorter and rounder in the presence of methadone. Furthermore, analysis of oxygen uptake by isolated rat liver mitochondria suggested that methadone affected mitochondrial Ca2+ uptake in a respiratory substrate-dependent way. We conclude that methadone causes failure of intracellular Ca2+ homeostasis, and this effect is associated with morphological and functional changes of mitochondria. Likely, this mechanism contributes to degenerative side effects associated with methadone treatment. PMID:22778742

  13. GFP facilitates native purification of recombinant perlucin derivatives and delays the precipitation of calcium carbonate.

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    Eva Weber

    Full Text Available Insolubility is one of the possible functions of proteins involved in biomineralization, which often limits their native purification. This becomes a major problem especially when recombinant expression systems are required to obtain larger amounts. For example, the mollusc shell provides a rich source of unconventional proteins, which can interfere in manifold ways with different mineral phases and interfaces. Therefore, the relevance of such proteins for biotechnological processes is still in its infancy. Here we report a simple and reproducible purification procedure for a GFP-tagged lectin involved in biomineralization, originally isolated from mother-of-pearl in abalone shells. An optimization of E. coli host cell culture conditions was the key to obtain reasonable yields and high degrees of purity by using simple one-step affinity chromatography. We identified a dual functional role for the GFP domain when it became part of a mineralizing system in vitro. First, the GFP domain improved the solubility of an otherwise insoluble protein, in this case recombinant perlucin derivatives. Second, GFP inhibited calcium carbonate precipitation in a concentration dependent manner. This was demonstrated here using a simple bulk assay over a time period of 400 seconds. At concentrations of 2 µg/ml and higher, the inhibitory effect was observed predominantly for HCO(3 (- as the first ionic interaction partner, but not necessarily for Ca(2+. The interference of GFP-tagged perlucin derivatives with the precipitation of calcium carbonate generated different types of GFP-fluorescent composite calcite crystals. GFP-tagging offers therefore a genetically tunable tool to gently modify mechanical and optical properties of synthetic biocomposite minerals.

  14. A functional tandem between transient receptor potential canonical channels 6 and calcium-dependent chloride channels in human epithelial cells.

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    Bertrand, Johanna; Dannhoffer, Luc; Antigny, Fabrice; Vachel, Laura; Jayle, Christophe; Vandebrouck, Clarisse; Becq, Frédéric; Norez, Caroline

    2015-10-15

    TRPC6 plays important human physiological functions, notably in artery and arterioles constriction, in regulation of vascular volume and in bronchial muscle constriction. It is implicated in pulmonary hypertension, cardiovascular disease, and focal segmental glomerulosclerosis and seems to play a role in cancer development. Previously, we identified Guanabenz, an α2-adrenergic agonist used for hypertension treatment (Wytensin®), as an activator of calcium-dependent chloride channels (CaCC) in human Cystic Fibrosis (CF) nasal epithelial cells by transiently increasing [Ca2+]i via an influx of extracellular Ca2+. In this study, using assays to measure chloride channel activity, we show that guanabenz is an activator of CaCC in freshly dissociated human bronchial epithelial cells from three CF patients with various genotypes (F508del/F508del, F508del/R1066C, F508del/H1085R). We further characterised the effect of guanabenz and show that it is independent of α-adrenergic receptors, is inhibited by the TRPC family inhibitor SKF-96365 but not by the TRPV family inhibitor ruthenium red. Using western-blotting, Ca2+ measurements and iodide efflux assay, we found that TRPC1 siRNA has no effect on guanabenz induced responses whereas TRPC6 siRNA prevented the guanabenz-dependent Ca2+ influx and the CaCC-dependent activity stimulated by guanabenz. In conclusion, we show that TRPC6 channel is pivotal for the activation of CaCC by guanabenz through a α2-adrenergic-independent pathway in human airway epithelial cells. We suggest propose a functional coupling between TRPC6 and CaCC and guanabenz as a potential TRPC6 activator for exploring TRPC6 and CaCC channel functions and corresponding channelopathies. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Parvalbumin overexpression alters immune-mediated increases in intracellular calcium, and delays disease onset in a transgenic model of familial amyotrophic lateral sclerosis

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    Beers, D. R.; Ho, B. K.; Siklos, L.; Alexianu, M. E.; Mosier, D. R.; Mohamed, A. H.; Otsuka, Y.; Kozovska, M. E.; McAlhany, R. E.; Smith, R. G.; hide

    2001-01-01

    Intracellular calcium is increased in vulnerable spinal motoneurons in immune-mediated as well as transgenic models of amyotrophic lateral sclerosis (ALS). To determine whether intracellular calcium levels are influenced by the calcium-binding protein parvalbumin, we developed transgenic mice overexpressing parvalbumin in spinal motoneurons. ALS immunoglobulins increased intracellular calcium and spontaneous transmitter release at motoneuron terminals in control animals, but not in parvalbumin overexpressing transgenic mice. Parvalbumin transgenic mice interbred with mutant SOD1 (mSOD1) transgenic mice, an animal model of familial ALS, had significantly reduced motoneuron loss, and had delayed disease onset (17%) and prolonged survival (11%) when compared with mice with only the mSOD1 transgene. These results affirm the importance of the calcium binding protein parvalbumin in altering calcium homeostasis in motoneurons. The increased motoneuron parvalbumin can significantly attenuate the immune-mediated increases in calcium and to a lesser extent compensate for the mSOD1-mediated 'toxic-gain-of-function' in transgenic mice.

  16. Understanding spatial and temporal patterning of astrocyte calcium transients via interactions between network transport and extracellular diffusion

    Science.gov (United States)

    Shtrahman, E.; Maruyama, D.; Olariu, E.; Fink, C. G.; Zochowski, M.

    2017-02-01

    Astrocytes form interconnected networks in the brain and communicate via calcium signaling. We investigate how modes of coupling between astrocytes influence the spatio-temporal patterns of calcium signaling within astrocyte networks and specifically how these network interactions promote coordination within this group of cells. To investigate these complex phenomena, we study reduced cultured networks of astrocytes and neurons. We image the spatial temporal patterns of astrocyte calcium activity and quantify how perturbing the coupling between astrocytes influences astrocyte activity patterns. To gain insight into the pattern formation observed in these cultured networks, we compare the experimentally observed calcium activity patterns to the patterns produced by a reduced computational model, where we represent astrocytes as simple units that integrate input through two mechanisms: gap junction coupling (network transport) and chemical release (extracellular diffusion). We examine the activity patterns in the simulated astrocyte network and their dependence upon these two coupling mechanisms. We find that gap junctions and extracellular chemical release interact in astrocyte networks to modulate the spatiotemporal patterns of their calcium dynamics. We show agreement between the computational and experimental findings, which suggests that the complex global patterns can be understood as a result of simple local coupling mechanisms.

  17. Simultaneous Quantification of Spatially Discordant Alternans in Voltage and Intracellular Calcium in Langendorff-Perfused Rabbit Hearts and Inconsistencies with Models of Cardiac Action Potentials and Ca Transients

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    Ilija Uzelac

    2017-10-01

    Full Text Available Rationale: Discordant alternans, a phenomenon in which the action potential duration (APDs and/or intracellular calcium transient durations (CaDs in different spatial regions of cardiac tissue are out of phase, present a dynamical instability for complex spatial dispersion that can be associated with long-QT syndrome (LQTS and the initiation of reentrant arrhythmias. Because the use of numerical simulations to investigate arrhythmic effects, such as acquired LQTS by drugs is beginning to be studied by the FDA, it is crucial to validate mathematical models that may be used during this process.Objective: In this study, we characterized with high spatio-temporal resolution the development of discordant alternans patterns in transmembrane voltage (Vm and intracellular calcium concentration ([Cai]+2 as a function of pacing period in rabbit hearts. Then we compared the dynamics to that of the latest state-of-the-art model for ventricular action potentials and calcium transients to better understand the underlying mechanisms of discordant alternans and compared the experimental data to the mathematical models representing Vm and [Cai]+2 dynamics.Methods and Results: We performed simultaneous dual optical mapping imaging of Vm and [Cai]+2 in Langendorff-perfused rabbit hearts with higher spatial resolutions compared with previous studies. The rabbit hearts developed discordant alternans through decreased pacing period protocols and we quantified the presence of multiple nodal points along the direction of wave propagation, both in APD and CaD, and compared these findings with results from theoretical models. In experiments, the nodal lines of CaD alternans have a steeper slope than those of APD alternans, but not as steep as predicted by numerical simulations in rabbit models. We further quantified several additional discrepancies between models and experiments.Conclusions: Alternans in CaD have nodal lines that are about an order of magnitude steeper

  18. Spine Calcium Transients Induced by Synaptically-Evoked Action Potentials Can Predict Synapse Location and Establish Synaptic Democracy

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    Meredith, Rhiannon M.; van Ooyen, Arjen

    2012-01-01

    CA1 pyramidal neurons receive hundreds of synaptic inputs at different distances from the soma. Distance-dependent synaptic scaling enables distal and proximal synapses to influence the somatic membrane equally, a phenomenon called “synaptic democracy”. How this is established is unclear. The backpropagating action potential (BAP) is hypothesised to provide distance-dependent information to synapses, allowing synaptic strengths to scale accordingly. Experimental measurements show that a BAP evoked by current injection at the soma causes calcium currents in the apical shaft whose amplitudes decay with distance from the soma. However, in vivo action potentials are not induced by somatic current injection but by synaptic inputs along the dendrites, which creates a different excitable state of the dendrites. Due to technical limitations, it is not possible to study experimentally whether distance information can also be provided by synaptically-evoked BAPs. Therefore we adapted a realistic morphological and electrophysiological model to measure BAP-induced voltage and calcium signals in spines after Schaffer collateral synapse stimulation. We show that peak calcium concentration is highly correlated with soma-synapse distance under a number of physiologically-realistic suprathreshold stimulation regimes and for a range of dendritic morphologies. Peak calcium levels also predicted the attenuation of the EPSP across the dendritic tree. Furthermore, we show that peak calcium can be used to set up a synaptic democracy in a homeostatic manner, whereby synapses regulate their synaptic strength on the basis of the difference between peak calcium and a uniform target value. We conclude that information derived from synaptically-generated BAPs can indicate synapse location and can subsequently be utilised to implement a synaptic democracy. PMID:22719238

  19. Comparison of dendritic calcium transients in juvenile wild type and SOD1G93A mouse lumbar motoneurons

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    Katharina Ann Quinlan

    2015-04-01

    Full Text Available Previous studies of spinal motoneurons in the SOD1 mouse model of amyotrophic lateral sclerosis have shown alterations long before disease onset, including increased dendritic branching, increased persistent Na+ and Ca2+ currents, and impaired axonal transport. In this study dendritic Ca2+ entry was investigated using 2 photon excitation fluorescence microscopy and whole-cell patch-clamp of juvenile (P4-11 motoneurons. Neurons were filled with both Ca2+ Green-1 and Texas Red dextrans, and line scans performed throughout. Steps were taken to account for different sources of variability, including 1 dye filling and laser penetration, 2 dendritic anatomy, and 3 the time elapsed from the start of recording. First, Ca2+ Green-1 fluorescence was normalized by Texas Red; next, neurons were reconstructed so anatomy could be evaluated; finally, time was recorded. Customized software detected the largest Ca2+ transients (area under the curve from each line scan and matched it with parameters above. Overall, larger dendritic diameter and shorter path distance from the soma were significant predictors of larger transients, while time was not significant up to 2 hours (data thereafter was dropped. However, Ca2+ transients showed additional variability. Controlling for previous factors, significant variation was found between Ca2+ signals from different processes of the same neuron in 3/7 neurons. This could reflect differential expression of Ca2+ channels, local neuromodulation or other variations. Finally, Ca2+ transients in SOD1G93A motoneurons were significantly smaller than in non-transgenic motoneurons. In conclusion, motoneuron processes show highly variable Ca2+ transients, but these transients are smaller overall SOD1G93A motoneurons.

  20. N- and L-type voltage-gated calcium channels mediate fast calcium transients in axonal shafts of mouse peripheral nerve.

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    Ruxandra eBarzan

    2016-06-01

    Full Text Available In the peripheral nervous system a vast number of axons are accommodated within fiber bundles that constitute peripheral nerves. A major function of peripheral axons is to propagate action potentials along their length, and hence they are equipped with Na+ and K+ channels, which ensure successful generation, conduction and termination of each action potential. However little is known about Ca2+ ion channels expressed along peripheral axons and their possible functional significance. The goal of the present study was to test whether voltage-gated Ca2+ channels (VGCCs are present along peripheral nerve axons in situ and mediate rapid activity-dependent Ca2+ elevations under physiological circumstances. To address this question we used mouse sciatic nerve slices, Ca2+ indicator Oregon Green BAPTA-1, and 2-photon Ca2+ imaging in fast line scan mode (500 Hz. We report that transient increases in intra-axonal Ca2+ concentration take place along peripheral nerve axons in situ when axons are stimulated electrically with single pulses. Furthermore, we show for the first time that Ca2+ transients in peripheral nerves are fast, i.e. occur in a millisecond time-domain. Combining Ca2+ imaging and pharmacology with specific blockers of different VGCCs subtypes we demonstrate that Ca2+ transients in peripheral nerves are mediated mainly by N-type and L-type VGCCs. Discovery of fast Ca2+ entry into the axonal shafts through VGCCs in peripheral nerves suggests that Ca2+ may be involved in regulation of action potential propagation and/or properties in this system, or mediate neurotransmitter release along peripheral axons as it occurs in the optic nerve and white matter of the central nervous system.

  1. Streptococcus pneumoniae Infection of Host Epithelial Cells via Polymeric Immunoglobulin Receptor Transiently Induces Calcium Release from Intracellular Stores*

    Science.gov (United States)

    Asmat, Tauseef M.; Agarwal, Vaibhav; Räth, Susann; Hildebrandt, Jan-Peter; Hammerschmidt, Sven

    2011-01-01

    The pneumococcal surface protein C (PspC) is a major adhesin of Streptococcus pneumoniae (pneumococci) that interacts in a human-specific manner with the ectodomain of the human polymeric immunoglobulin receptor (pIgR) produced by respiratory epithelial cells. This interaction promotes bacterial colonization and bacterial internalization by initiating host signal transduction cascades. Here, we examined alterations of intracellular calcium ([Ca2+]i) levels in epithelial cells during host cell infections with pneumococci via the PspC-hpIgR mechanism. The release of [Ca2+]i from intracellular stores in host cells was significantly increased by wild-type pneumococci but not by PspC-deficient pneumococci. The increase in [Ca2+]i was dependent on phospholipase C as pretreatment of cells with a phospholipase C-specific inhibitor U73122 abolished the increase in [Ca2+]i. In addition, we demonstrated the effect of [Ca2+]i on pneumococcal internalization by epithelial cells. Uptake of pneumococci was significantly increased after pretreatment of epithelial cells with the cell-permeable calcium chelator 1,2-bis-(o-aminophenoxy)-ethane-N,N,N′,N′-tetraacetic acid-tetraacetoxymethyl ester or use of EGTA as an extracellular Ca2+-chelating agent. In contrast, thapsigargin, an inhibitor of endoplasmic reticulum Ca2+ATPase, which increases [Ca2+]i in a sustained fashion, significantly reduced pIgR-mediated pneumococcal invasion. Importantly, pneumococcal adherence to pIgR-expressing cells was not altered in the presence of inhibitors as demonstrated by immunofluorescence microscopy. In conclusion, these results demonstrate that pneumococcal infections induce mobilization of [Ca2+]i from intracellular stores. This may constitute a defense response of host cells as the experimental reduction of intracellular calcium levels facilitates pneumococcal internalization by pIgR-expressing cells, whereas elevated calcium levels diminished bacterial internalization by host epithelial

  2. Streptococcus pneumoniae infection of host epithelial cells via polymeric immunoglobulin receptor transiently induces calcium release from intracellular stores.

    Science.gov (United States)

    Asmat, Tauseef M; Agarwal, Vaibhav; Räth, Susann; Hildebrandt, Jan-Peter; Hammerschmidt, Sven

    2011-05-20

    The pneumococcal surface protein C (PspC) is a major adhesin of Streptococcus pneumoniae (pneumococci) that interacts in a human-specific manner with the ectodomain of the human polymeric immunoglobulin receptor (pIgR) produced by respiratory epithelial cells. This interaction promotes bacterial colonization and bacterial internalization by initiating host signal transduction cascades. Here, we examined alterations of intracellular calcium ([Ca(2+)](i)) levels in epithelial cells during host cell infections with pneumococci via the PspC-hpIgR mechanism. The release of [Ca(2+)](i) from intracellular stores in host cells was significantly increased by wild-type pneumococci but not by PspC-deficient pneumococci. The increase in [Ca(2+)](i) was dependent on phospholipase C as pretreatment of cells with a phospholipase C-specific inhibitor U73122 abolished the increase in [Ca(2+)](i). In addition, we demonstrated the effect of [Ca(2+)](i) on pneumococcal internalization by epithelial cells. Uptake of pneumococci was significantly increased after pretreatment of epithelial cells with the cell-permeable calcium chelator 1,2-bis-(o-aminophenoxy)-ethane-N,N,N',N'-tetraacetic acid-tetraacetoxymethyl ester or use of EGTA as an extracellular Ca(2+)-chelating agent. In contrast, thapsigargin, an inhibitor of endoplasmic reticulum Ca(2+)ATPase, which increases [Ca(2+)](i) in a sustained fashion, significantly reduced pIgR-mediated pneumococcal invasion. Importantly, pneumococcal adherence to pIgR-expressing cells was not altered in the presence of inhibitors as demonstrated by immunofluorescence microscopy. In conclusion, these results demonstrate that pneumococcal infections induce mobilization of [Ca(2+)](i) from intracellular stores. This may constitute a defense response of host cells as the experimental reduction of intracellular calcium levels facilitates pneumococcal internalization by pIgR-expressing cells, whereas elevated calcium levels diminished bacterial

  3. Transient decomplementation of mice delays onset of experimental autoimmune encephalomyelitis and impairs MOG-specific T cell response and autoantibody production.

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    Terényi, Nóra; Nagy, Nándor; Papp, Krisztián; Prechl, József; Oláh, Imre; Erdei, Anna

    2009-11-01

    Multiple sclerosis (MS) is the most common inflammatory and demyelinating disease of the central nervous system. In both MS and its animal model experimental autoimmune encephalomyelitis (EAE), it is thought that infiltrating CD4(+) T cells initiate an inflammatory process and collect other immune effectors to mediate tissue damage. The pathophysiology of the disease however remains unclear. Here we focus on the role of the complement system in the pathomechanism of EAE, employing mice with transiently depleted complement activity achieved by a single injection of cobra venom factor (CVF) 2 days before the induction of the disease. Our results show that in decomplemented C57BL/6 mice immunized with myelin oligodendrocyte glycoprotein (MOG) peptide 35-55, the onset of the disease is significantly delayed. In SJL/J mice which develop a relapsing-remitting form of EAE after injection with proteolipid protein (PLP) peptide 139-151, the attenuation of both phases could be observed in CVF-treated animals. In C57BL/6 mice the level of MOG specific autoantibodies and their complement activating capacity evaluated on day 21 were found significantly reduced in animals transiently decomplemented before induction of the disease. The in vitro response of T cells isolated from the lymph nodes of MOG-immunized animals at the onset of EAE was also investigated. We found that the proliferative capacity of MOG-specific T lymphocytes derived from CVF treated animals is significantly reduced, in agreement with the histology of the spinal cords showing a decreased infiltration of CD4(+) T cells in these mice. Our data suggest, that lack of systemic complement at the time of induction of EAE delays the onset and attenuates the course of the disease most probably via diminishing the response of MOG-specific T cells and production of autoantibodies.

  4. Activation of Human Transient Receptor Potential Melastatin-8 (TRPM8) by Calcium-Rich Particulate Materials and Effects on Human Lung Cells.

    Science.gov (United States)

    Lamb, John G; Romero, Erin G; Lu, Zhenyu; Marcus, Seychelle K; Peterson, Hannah C; Veranth, John M; Deering-Rice, Cassandra E; Reilly, Christopher A

    2017-10-16

    To better understand how adverse health effects are caused by particulate materials, and to develop preventative measures, it is important to identify the properties of particles and proteins that link exposure with specific biological outcomes. Coal fly ash (CFA) is a by-product of coal combustion that can affect human health. Here we show that human transient receptor potential melastatin-8 (TRPM8) and an N-terminally truncated TRPM8 variant (TRPM8-Δ801) are activated by CFA and calcium-rich nanoparticles and/or soluble salts within CFA. Human TRPM8 activation by CFA was potentiated by cold temperature and involved the phosphatidylinositol 4,5-bisphosphate binding site (L1008). Activation also occurred independent of the icilin and menthol binding site residue Y745, as well as to a large extent, the N-terminal amino acids 1-800. CFA, calcium nanoparticles and calcium salts also activated TRPV1 and TRPA1, but not TRPV4. Finally, CFA treatment caused CXCL1 and IL-8 mRNA induction in BEAS-2B and primary human bronchial epithelial cells through activation of both TRPM8 and TRPV1. However, neither mouse nor rat TRPM8 were activated by these materials, and Trpm8-knockout had no effect on cytokine induction in the lungs of mice following CFA instillation. These results imply that TRPM8, in conjunction with TRPV1 and TRPA1, might sense selected forms of inhaled particulate materials in human airways, shaping cellular responses to these materials. These findings improve our understanding of how and why certain particulate materials elicit different responses in biological systems, as well as ways in which certain particles might affect human health. The American Society for Pharmacology and Experimental Therapeutics.

  5. Blast overpressure waves induce transient anxiety and regional changes in cerebral glucose metabolism and delayed hyperarousal in rats

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    Hibah Omar Awwad

    2015-06-01

    Full Text Available Physiological alterations, anxiety and cognitive disorders are strongly associated with blast-induced traumatic brain injury (blast TBI and are common symptoms in service personnel exposed to blasts. Since 2006, 25-30,000 new TBI cases are diagnosed annually in U.S. Service members; increasing evidence confirms that primary blast exposure causes diffuse axonal injury and is often accompanied by altered behavioral outcomes. Behavioral and acute metabolic effects resulting from blast to the head in the absence of thoracic contributions from the periphery were examined following a single blast wave directed to the head of male Sprague-Dawley rats protected by a lead shield over the torso. An 80 psi head blast produced cognitive deficits that were detected in working memory. Blast TBI rats displayed increased anxiety as determined by elevated plus maze at day 9 post-blast compared to sham rats; blast TBI rats spent significantly more time than the sham controls in the closed arms (p<0.05; n=8-11. Interestingly, anxiety symptoms were absent at days 22 and 48 post-blast. Instead, blast TBI rats displayed hyperactivity and increased rearing behavior at day 48 post-blast compared to sham rats. Blast TBI rats also exhibited suppressed acoustic startle responses, but similar pre-pulse inhibition at day 15 post-blast compared to sham rats. Acute physiological alterations in cerebral glucose metabolism were determined by positron emission tomography 1 and 9 days post-blast using F-18-fluorodeoxyglucose. Global glucose uptake in blast TBI rat brains increased at day 1 post-blast (p<0.05; n=4-6 and returned to sham levels by day 9. Our results indicate a transient increase in cerebral metabolism following a blast injury. Markers for reactive astrogliosis and neuronal damage were noted by immunoblotting motor cortex tissue from day 10 post-blast in blast TBI rats compared to sham controls (p<0.05; n=5-6.

  6. Ca analysis: An Excel based program for the analysis of intracellular calcium transients including multiple, simultaneous regression analysis☆

    Science.gov (United States)

    Greensmith, David J.

    2014-01-01

    Here I present an Excel based program for the analysis of intracellular Ca transients recorded using fluorescent indicators. The program can perform all the necessary steps which convert recorded raw voltage changes into meaningful physiological information. The program performs two fundamental processes. (1) It can prepare the raw signal by several methods. (2) It can then be used to analyze the prepared data to provide information such as absolute intracellular Ca levels. Also, the rates of change of Ca can be measured using multiple, simultaneous regression analysis. I demonstrate that this program performs equally well as commercially available software, but has numerous advantages, namely creating a simplified, self-contained analysis workflow. PMID:24125908

  7. Ca analysis: an Excel based program for the analysis of intracellular calcium transients including multiple, simultaneous regression analysis.

    Science.gov (United States)

    Greensmith, David J

    2014-01-01

    Here I present an Excel based program for the analysis of intracellular Ca transients recorded using fluorescent indicators. The program can perform all the necessary steps which convert recorded raw voltage changes into meaningful physiological information. The program performs two fundamental processes. (1) It can prepare the raw signal by several methods. (2) It can then be used to analyze the prepared data to provide information such as absolute intracellular Ca levels. Also, the rates of change of Ca can be measured using multiple, simultaneous regression analysis. I demonstrate that this program performs equally well as commercially available software, but has numerous advantages, namely creating a simplified, self-contained analysis workflow. Copyright © 2013 The Author. Published by Elsevier Ireland Ltd.. All rights reserved.

  8. Antipsychotic drugs up-regulate tryptophan hydroxylase in ADF neurons of Caenorhabditis elegans: role of calcium-calmodulin-dependent protein kinase II and transient receptor potential vanilloid channel.

    Science.gov (United States)

    Donohoe, Dallas R; Phan, Thang; Weeks, Kathrine; Aamodt, Eric J; Dwyer, Donard S

    2008-08-15

    Antipsychotic drugs produce acute behavioral effects through antagonism of dopamine and serotonin receptors, and long-term adaptive responses that are not well understood. The goal of the study presented here was to use Caenorhabditis elegans to investigate the molecular mechanism or mechanisms that contribute to adaptive responses produced by antipsychotic drugs. First-generation antipsychotics, trifluoperazine and fluphenazine, and second-generation drugs, clozapine and olanzapine, increased the expression of tryptophan hydroxylase-1::green fluorescent protein (TPH-1::GFP) and serotonin in the ADF neurons of C. elegans. This response was absent or diminished in mutant strains lacking the transient receptor potential vanilloid channel (TRPV; osm-9) or calcium/calmodulin-dependent protein kinase II (CaMKII; unc-43). The role of calcium signaling was further implicated by the finding that a selective antagonist of calmodulin and a calcineurin inhibitor also enhanced TPH-1::GFP expression. The ADF neurons modulate foraging behavior (turns/reversals off food) through serotonin production. We found that short-term exposure to the antipsychotic drugs altered the frequency of turns/reversals off food. This response was mediated through dopamine and serotonin receptors and was abolished in serotonin-deficient mutants (tph-1) and strains lacking the SER-1 and MOD-1 serotonin receptors. Consistent with the increase in serotonin in the ADF neurons induced by the drugs, drug withdrawal after 24-hr treatment was accompanied by a rebound in the number of turns/reversals, which demonstrates behavioral adaptation in serotonergic systems. Characterization of the cellular, molecular, and behavioral adaptations to continuous exposure to antipsychotic drugs may provide insight into the long-term clinical effects of these medications.

  9. Actions of a hydrogen sulfide donor (NaHS) on transient sodium, persistent sodium, and voltage-gated calcium currents in neurons of the subfornical organ.

    Science.gov (United States)

    Kuksis, Markus; Ferguson, Alastair V

    2015-09-01

    Hydrogen sulfide (H2S) is an endogenously found gasotransmitter that has been implicated in a variety of beneficial physiological functions. This study was performed to investigate the cellular mechanisms underlying actions of H2S previously observed in subfornical organ (SFO), where H2S acts to regulate blood pressure through a depolarization of the membrane and an overall increase in the excitability of SFO neurons. We used whole cell patch-clamp electrophysiology in the voltage-clamp configuration to analyze the effect of 1 mM NaHS, an H2S donor, on voltage-gated potassium, sodium, and calcium currents. We observed no effect of NaHS on potassium currents; however, both voltage-gated sodium currents (persistent and transient) and the N-type calcium current had a depolarized activation curve and an enhanced peak-induced current in response to a series of voltage-step and ramp protocols run in the control and NaHS conditions. These effects were not responsible for the previously observed depolarization of the membrane potential, as depolarizing effects of H2S were still observed following block of these conductances with tetrodotoxin (5 μM) and ω-conotoxin-GVIA (100 nM). Our studies are the first to investigate the effect of H2S on a variety of voltage-gated conductances in a single brain area, and although they do not explain mechanisms underlying the depolarizing actions of H2S on SFO neurons, they provide evidence of potential mechanisms through which this gasotransmitter influences the excitability of neurons in this important brain area as a consequence of the modulation of multiple ion channels. Copyright © 2015 the American Physiological Society.

  10. Efficacy of MEM 1003, a novel calcium channel blocker, in delay and trace eyeblink conditioning in older rabbits.

    Science.gov (United States)

    Rose, Gregory M; Ong, Voon S; Woodruff-Pak, Diana S

    2007-05-01

    Eyeblink conditioning is a relatively simple form of associative learning that shows neurobiological and behavioral parallels across several species, including humans. Aged subjects acquire eyeblink conditioning more slowly than young ones. In addition, eyeblink conditioning effectively discriminates patients with Alzheimer's disease from healthy older adults. The present study evaluated the effect of a novel L-type Ca2+ channel antagonist, MEM 1003, on delay and trace eyeblink conditioning in older (mean 33.4 months old) female New Zealand white rabbits. In the delay conditioning paradigm, an 850 ms tone conditioning stimulus (CS) was followed 750 ms after its onset by a 100 ms corneal air puff. Several trace conditioning paradigms were evaluated, with a silent period of 300, 400 or 500 ms between the end of the tone CS and the delivery of the air puff. Learning was more difficult in the longer trace paradigms than in the delay paradigm. MEM 1003, at a dose of 2.0 mg/kg, s.c., given daily 30 min prior to training on each of the 15 training days, enhanced learning compared to vehicle injections in both delay and trace paradigms. However, higher or lower doses were ineffective. These results support previous work demonstrating that modulation of Ca2+ channel activity can reduce age-related cognitive impairments.

  11. Stabilization of diastolic calcium signal via calcium pump regulation of complex local calcium releases and transient decay in a computational model of cardiac pacemaker cell with individual release channels.

    Directory of Open Access Journals (Sweden)

    Alexander V Maltsev

    2017-08-01

    Full Text Available Intracellular Local Ca releases (LCRs from sarcoplasmic reticulum (SR regulate cardiac pacemaker cell function by activation of electrogenic Na/Ca exchanger (NCX during diastole. Prior studies demonstrated the existence of powerful compensatory mechanisms of LCR regulation via a complex local cross-talk of Ca pump, release and NCX. One major obstacle to study these mechanisms is that LCR exhibit complex Ca release propagation patterns (including merges and separations that have not been characterized. Here we developed new terminology, classification, and computer algorithms for automatic detection of numerically simulated LCRs and examined LCR regulation by SR Ca pumping rate (Pup that provides a major contribution to fight-or-flight response. In our simulations the faster SR Ca pumping accelerates action potential-induced Ca transient decay and quickly clears Ca under the cell membrane in diastole, preventing premature releases. Then the SR generates an earlier, more synchronized, and stronger diastolic LCR signal activating an earlier and larger inward NCX current. LCRs at higher Pup exhibit larger amplitudes and faster propagation with more collisions to each other. The LCRs overlap with Ca transient decay, causing an elevation of the average diastolic [Ca] nadir to ~200 nM (at Pup = 24 mM/s. Background Ca (in locations lacking LCRs quickly decays to resting Ca levels (<100 nM at high Pup, but remained elevated during slower decay at low Pup. Release propagation is facilitated at higher Pup by a larger LCR amplitude, whereas at low Pup by higher background Ca. While at low Pup LCRs show smaller amplitudes, their larger durations and sizes combined with longer transient decay stabilize integrals of diastolic Ca and NCX current signals. Thus, the local interplay of SR Ca pump and release channels regulates LCRs and Ca transient decay to insure fail-safe pacemaker cell operation within a wide range of rates.

  12. Stabilization of diastolic calcium signal via calcium pump regulation of complex local calcium releases and transient decay in a computational model of cardiac pacemaker cell with individual release channels.

    Science.gov (United States)

    Maltsev, Alexander V; Maltsev, Victor A; Stern, Michael D

    2017-08-01

    Intracellular Local Ca releases (LCRs) from sarcoplasmic reticulum (SR) regulate cardiac pacemaker cell function by activation of electrogenic Na/Ca exchanger (NCX) during diastole. Prior studies demonstrated the existence of powerful compensatory mechanisms of LCR regulation via a complex local cross-talk of Ca pump, release and NCX. One major obstacle to study these mechanisms is that LCR exhibit complex Ca release propagation patterns (including merges and separations) that have not been characterized. Here we developed new terminology, classification, and computer algorithms for automatic detection of numerically simulated LCRs and examined LCR regulation by SR Ca pumping rate (Pup) that provides a major contribution to fight-or-flight response. In our simulations the faster SR Ca pumping accelerates action potential-induced Ca transient decay and quickly clears Ca under the cell membrane in diastole, preventing premature releases. Then the SR generates an earlier, more synchronized, and stronger diastolic LCR signal activating an earlier and larger inward NCX current. LCRs at higher Pup exhibit larger amplitudes and faster propagation with more collisions to each other. The LCRs overlap with Ca transient decay, causing an elevation of the average diastolic [Ca] nadir to ~200 nM (at Pup = 24 mM/s). Background Ca (in locations lacking LCRs) quickly decays to resting Ca levels (pump and release channels regulates LCRs and Ca transient decay to insure fail-safe pacemaker cell operation within a wide range of rates.

  13. Lanthanum carbonate delays progression of coronary artery calcification compared with calcium-based phosphate binders in patients on hemodialysis: a pilot study.

    Science.gov (United States)

    Ohtake, Takayasu; Kobayashi, Shuzo; Oka, Machiko; Furuya, Rei; Iwagami, Masao; Tsutsumi, Daimu; Mochida, Yasuhiro; Maesato, Kyoko; Ishioka, Kunihiro; Moriya, Hidekazu; Hidaka, Sumi

    2013-09-01

    Coronary artery calcification (CAC) is associated with future cardiovascular events and/or death of patients on hemodialysis (HD). We investigated whether progression of CAC in patients on HD could be delayed by switching from a calcium (Ca)-based phosphate (Pi) binder to lanthanum carbonate. The CAC scores were evaluated at study enrollment and after 6 months in 52 patients on HD using calcium carbonate (CC) as a Pi binder. Patients were randomly divided into 2 groups assigned to receive either CC or lanthanum carbonate (LC), and the CAC scores were evaluated after a 6-month treatment period. Progression of CAC was assessed, as were serum levels of Ca, Pi, and intact parathyroid hormone (iPTH). Forty-two patients completed the study (23 receiving CC and 19 receiving LC). In the 6 months prior to randomization, all patients were treated with CC. During this 6-month period, the CAC scores increased significantly in all 42 patients. Once randomized, there was significantly less progression in the group treated with LC than with CC. Changes in CAC scores from 6 to 12 months were significantly smaller in the LC group than the CC group (-288.9 ± 1176.4 vs 107.1 ± 559.6, P = .036), and percentage changes were also significantly different (-6.4% vs 41.2%, P = .024). Serum Ca, Pi, and iPTH levels were similar in both groups during the study period. This pilot study suggested that LC delayed progression of CAC in patients on HD compared with CC.

  14. SKF-96365 activates cytoprotective autophagy to delay apoptosis in colorectal cancer cells through inhibition of the calcium/CaMKIIγ/AKT-mediated pathway.

    Science.gov (United States)

    Jing, Zhao; Sui, Xinbing; Yao, Junlin; Xie, Jiansheng; Jiang, Liming; Zhou, Yubin; Pan, Hongming; Han, Weidong

    2016-03-28

    Store-operated Ca(2+) entry (SOCE) inhibitors are emerging as an attractive new generation of anti-cancer drugs. Here, we report that SKF-96365, an SOCE inhibitor, exhibits potent anti-neoplastic activity by inducing cell-cycle arrest and apoptosis in colorectal cancer cells. In the meantime, SKF-96365 also induces cytoprotective autophagy to delay apoptosis by preventing the release of cytochrome c (cyt c) from the mitochondria into the cytoplasm. Mechanistically, SKF-96365 treatment inhibited the calcium/calmodulin-dependent protein kinase IIγ (CaMKIIγ)/AKT signaling cascade in vitro and in vivo. Overexpression of CaMKIIγ or AKT abolished the effects of SKF-96365 on cancer cells, suggesting a critical role of the CaMKIIγ/AKT signaling pathway in SFK-96365-induced biological effects. Moreover, Hydroxychloroquine (HCQ), an FDA-approved drug used to inhibit autophagy, could significantly augment the anti-cancer effect of SFK-96365 in a mouse xenograft model. To our best knowledge, this is the first report to demonstrate that calcium/CaMKIIγ/AKT signaling can regulate apoptosis and autophagy simultaneously in cancer cells, and the combination of the SOCE inhibitor SKF-96365 with autophagy inhibitors represents a promising strategy for treating patients with colorectal cancer. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  15. Impaired calcium mobilization in natural killer cells from chronic fatigue syndrome/myalgic encephalomyelitis patients is associated with transient receptor potential melastatin 3 ion channels.

    Science.gov (United States)

    Nguyen, T; Johnston, S; Clarke, L; Smith, P; Staines, D; Marshall-Gradisnik, S

    2017-02-01

    Transient receptor potential melastatin subfamily 3 (TRPM3) ion channels play a role in calcium (Ca(2+) ) cell signalling. Reduced TRPM3 protein expression has been identified in chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME) patients. However, the significance of TRPM3 and association with intracellular Ca(2+) mobilization has yet to be determined. Fifteen CFS/ME patients (mean age 48·82 ± 9·83 years) and 25 healthy controls (mean age 39·2 ± 12·12 years) were examined. Isolated natural killer (NK) cells were labelled with fluorescent antibodies to determine TRPM3, CD107a and CD69 receptors on CD56(dim) CD16(+) NK cells and CD56(bright) CD16(dim/-) NK cells. Ca(2+) flux and NK cytotoxicity activity was measured under various stimulants, including pregnenolone sulphate (PregS), thapsigargin (TG), 2-aminoethoxydiphenyl borate (2APB) and ionomycin. Unstimulated CD56(bright) CD16(dim/-) NK cells showed significantly reduced TRPM3 receptors in CFS/ME compared with healthy controls (HC). Ca(2+) flux showed no significant difference between groups. Moreover, PregS-stimulated CD56(bright) CD16(dim/-) NK cells showed a significant increase in Ca(2+) flux in CFS/ME patients compared with HC. By comparison, unstimulated CD56(dim) CD16(+) NK cells showed no significant difference in both Ca(2+) flux and TRPM3 expression. PregS-stimulated CD56(dim) CD16(+) NK cells increased TRPM3 expression significantly in CFS/ME, but this was not associated with a significant increase in Ca(2+) flux. Furthermore, TG-stimulated CD56(dim) CD16(+) NK cells increased K562 cell lysis prior to PregS stimulation in CFS/ME patients compared with HC. Differential expression of TRPM3 and Ca(2+) flux between NK cell subtypes may provide evidence for their role in the pathomechanism involving NK cell cytotoxicity activity in CFS/ME. © 2016 The Authors. Clinical & Experimental Immunology published by John Wiley & Sons Ltd on behalf of British Society for Immunology.

  16. Delay in onset of metabolic alkalosis during regional citrate anti-coagulation in continous renal replacement therapy with calcium-free replacement solution

    Directory of Open Access Journals (Sweden)

    See Kay

    2009-01-01

    Full Text Available Regional citrate anti-coagulation for continuous renal replacement therapy chelates calcium to produce the anti- coagulation effect. We hypothesise that a calcium-free replacement solution will require less citrate and produce fewer metabolic side effects. Fifty patients, in a Medical Intensive Care Unit of a tertiary teaching hospital (25 in each group, received continuous venovenous hemofiltration using either calcium-containing or calcium-free replacement solutions. Both groups had no significant differences in filter life, metabolic alkalosis, hypernatremia, hypocalcemia, and hypercalcemia. However, patients using calcium-containing solution developed metabolic alkalosis earlier, compared to patients using calcium-free solution (mean 24.6 hours,CI 0.8-48.4 vs. 37.2 hours, CI 9.4-65, P = 0.020. When calcium-containing replacement solution was used, more citrate was required (mean 280ml/h, CI 227.2-332.8 vs. 265ml/h, CI 203.4-326.6, P = 0.069, but less calcium was infused (mean 21.2 ml/h, CI 1.2-21.2 vs 51.6ml/h, CI 26.8-76.4, P ≤ 0.0001.

  17. Icariin, a Novel Blocker of Sodium and Calcium Channels, Eliminates Early and Delayed Afterdepolarizations, As Well As Triggered Activity, in Rabbit Cardiomyocytes

    Directory of Open Access Journals (Sweden)

    Wanzhen Jiang

    2017-05-01

    Full Text Available Icariin, a flavonoid monomer from Herba Epimedii, has confirmed pharmacological and biological effects. However, its effects on arrhythmias and cardiac electrophysiology remain unclear. Here we investigate the effects of icariin on ion currents and action potentials (APs in the rabbit myocardium. Furthermore, the effects of icariin on aconitine-induced arrhythmias were assessed in whole rabbits. Ion currents and APs were recorded in voltage-clamp and current-clamp mode in rabbit left ventricular myocytes (LVMs and left atrial myocytes (LAMs, respectively. Icariin significantly shortened action potential durations (APDs at 50 and 90% repolarization (APD50 and APD90 and reduced AP amplitude (APA and the maximum upstroke velocity (Vmax of APs in LAMs and LVMs; however, icariin had no effect on resting membrane potential (RMP in these cells. Icariin decreased the rate-dependence of the APD and completely abolished anemonia toxin II (ATX-II-induced early afterdepolarizations (EADs. Moreover, icariin significantly suppressed delayed afterdepolarizations (DADs and triggered activities (TAs elicited by isoproterenol (ISO, 1 μM and high extracellular calcium concentrations ([Ca2+]o, 3.6 mM in LVMs. Icariin also decreased INaT in a concentration-dependent manner in LAMs and LVMs, with IC50 values of 12.28 ± 0.29 μM (n = 8 cells/4 rabbits and 11.83 ± 0.92 μM (n = 10 cells/6 rabbits; p > 0.05 vs. LAMs, respectively, and reversed ATX-II-induced INaL in a concentration-dependent manner in LVMs. Furthermore, icariin attenuated ICaL in a dose-dependent manner in LVMs. The corresponding IC50 value was 4.78 ± 0.89 μM (n = 8 cells/4 rabbits, indicating that the aforementioned current in LVMs was 2.8-fold more sensitive to icariin than ICaL in LAMs (13.43 ± 2.73 μM; n = 9 cells/5 rabbits. Icariin induced leftward shifts in the steady-state inactivation curves of INaT and ICaL in LAMs and LVMs but did not have a significant effect on their activation

  18. Z944, a Novel Selective T-Type Calcium Channel Antagonist Delays the Progression of Seizures in the Amygdala Kindling Model.

    Directory of Open Access Journals (Sweden)

    Pablo Miguel Casillas-Espinosa

    Full Text Available Temporal lobe epilepsy (TLE is the most common form of drug resistant epilepsy. Current treatment is symptomatic, suppressing seizures, but has no disease modifying effect on epileptogenesis. We examined the effects of Z944, a potent T-type calcium channel antagonist, as an anti-seizure agent and against the progression of kindling in the amygdala kindling model of TLE. The anti-seizure efficacy of Z944 (5mg/kg, 10mg/kg, 30mg/kg and 100mg/kg was assessed in fully kindled rats (5 class V seizures as compared to vehicle, ethosuximide (ETX, 100mg/kg and carbamazepine (30mg/kg. Each animal received the seven treatments in a randomised manner. Seizure class and duration elicited by six post-drug stimulations was determined. To investigate for effects in delaying the progression of kindling, naive animals received Z944 (30mg/kg, ETX (100mg/kg or vehicle 30-minutes prior to each kindling stimulation up to a maximum of 30 stimulations, with seizure class and duration recorded after each stimulation. At the completion of drug treatment, CaV3.1, CaV3.2 and CaV3.3 mRNA expression levels were assessed in the hippocampus and amygdala using qPCR. Z944 was not effective at suppressing seizures in fully kindled rats compared to vehicle. Animals receiving Z944 required significantly more stimulations to evoke a class III (p<0.05, IV (p<0.01 or V (p<0.0001 seizure, and to reach a fully kindled state (p<0.01, than animals receiving vehicle. There was no significant difference in the mRNA expression of the T-type Ca2+ channels in the hippocampus or amygdala. Our results show that selectively targeting T-type Ca2+ channels with Z944 inhibits the progression of amygdala kindling. This could be a potential for a new therapeutic intervention to mitigate the development and progression of epilepsy.

  19. Monocytes from spontaneously hypertensive rats show increased store-operated and second messenger-operated calcium influx mediated by transient receptor potential canonical Type 3 channels

    DEFF Research Database (Denmark)

    Liu, Dao Yan; Scholze, Alexandra; Kreutz, Reinhold

    2007-01-01

    We recently showed that increased expression of the transient receptor potential canonical Type 3 (TRPC3) channel is associated with genetic hypertension. It is unknown whether store-operated TRPC3 channels, which are activated after depletion of intracellular stores, or second messenger-operated...

  20. Discrepancies between c-Kit positive and Ano1 positive ICC-SMP in the W/Wv and wild-type mouse colon; relationships with motor patterns and calcium transients.

    Science.gov (United States)

    Wang, Xuan-Yu; Chen, Ji-Hong; Li, Kongling; Zhu, Yong F; Wright, George W J; Huizinga, Jan D

    2014-09-01

    Interstitial cells of Cajal associated with the submuscular plexus (ICC-SMP) generate omnipresent slow-wave activity in the colon and are associated with prominent motor patterns. Our aim was to investigate colon motor dysfunction in W/W(v) mice in which the ICC are reportedly reduced. Whole organ colon motility was studied using spatio-temporal mapping; immunohistochemical staining was carried out for c-Kit and Ano1; calcium imaging was applied to ICC-SMP. Discrepancies between Ano1 and c-Kit staining were found in both wild-type and W/W(v) colon. ICC-SMP were reduced to ~50% in the W/W(v) mouse colon according to c-Kit immunohistochemistry, but Ano1 staining indicated a normal network of ICC-SMP. The latter was consistent with rhythmic calcium transients occurring at the submucosal border of the colon in W/W(v) mice, similar to the rhythmic transients in wild-type ICC-SMP. Furthermore, the motor pattern associated with ICC-SMP pacemaking, the so-called 'ripples' were normal in the W/W(v) colon. c-Kit is not a reliable marker for quantifying ICC-SMP in the mouse colon. Ano1 staining revealed a normal network of ICC-SMP consistent with the presence of a normal 'ripples' motor pattern. We detected a class of Ano1 positive c-Kit negative cells that do not depend on Kit expression for maintenance, a feature shared with ICC progenitors. © 2014 John Wiley & Sons Ltd.

  1. Effects of serum immunoglobulins from patients with complex regional pain syndrome (CRPS) on depolarisation-induced calcium transients in isolated dorsal root ganglion (DRG) neurons.

    Science.gov (United States)

    Reilly, Joanne M; Dharmalingam, Backialakshmi; Marsh, Stephen J; Thompson, Victoria; Goebel, Andreas; Brown, David A

    2016-03-01

    Complex regional pain syndrome (CRPS) is thought to have an auto-immune component. One such target recently proposed from the effects of auto-immune IgGs on Ca(2+) transients in cardiac myocytes and cell lines is the α1-adrenoceptor. We have tested whether such IgGs exerted comparable effects on nociceptive sensory neurons isolated from rat dorsal root ganglia. Depolarisation-induced [Ca(2+)]i transients were generated by applying 30 mM KCl for 2 min and monitored by Fura-2 fluorescence imaging. No IgGs tested (including 3 from CRPS patients) had any significant effect on these [Ca(2+)]i transients. However, IgG from one CRPS patient consistently and significantly reduced the K(+)-induced response of cells that had been pre-incubated for 24h with a mixture of inflammatory mediators (1 μM histamine, 5-hydroxytryptamine, bradykinin and PGE2). Since this pre-incubation also appeared to induce a comparable inhibitory response to the α1-agonist phenylephrine, this is compatible with the α1-adrenoceptor as a target for CRPS auto-immunity. A mechanism whereby this might enhance pain is suggested. Copyright © 2015. Published by Elsevier Inc.

  2. Effect of State Feedback Coupling and System Delays on the Transient Performance of Stand-Alone VSI with LC Output Filter

    DEFF Research Database (Denmark)

    Federico, de Bosio; de Sousa Ribeiro, Luiz Antonio; Freijedo Fernandez, Francisco Daniel

    2016-01-01

    The influence of state feedback coupling in the dynamics performance of power converters for stand-alone microgrids is investigated. Computation and PWM delays are the main factors that limit the achievable bandwidth of current regulators in digital implementations. In particular, the performance...... provided. A proportional resonant voltage controller is designed according to Nyquist criterion taking into account application requirements. For this purpose, a mathematical expression based on root locus analysis is proposed to find the minimum value of the fundamental resonant gain. Experimental tests...

  3. Acute, transient hemorrhagic hypotension does not aggravate structural damage or neurologic motor deficits but delays the long-term cognitive recovery following mild to moderate traumatic brain injury

    Science.gov (United States)

    Schütz, Christian; Stover, John F.; Thompson, Hilaire J.; Hoover, Rachel C.; Morales, Diego M.; Schouten, Joost W.; McMillan, Asenia; Soltesz, Kristie; Motta, Melissa; Spangler, Zachery; Neugebauer, Edmund; McIntosh, Tracy K.

    2008-01-01

    Objectives Posttraumatic hypotension is believed to increase morbidity and mortality in traumatically brain-injured patients. Using a clinically relevant model of combined traumatic brain injury with superimposed hemorrhagic hypotension in rats, the present study evaluated whether a reduction in mean arterial blood pressure aggravates regional brain edema formation, regional cell death, and neurologic motor/cognitive deficits associated with traumatic brain injury. Design Experimental prospective, randomized study in rodents. Setting Experimental laboratory at a university hospital. Subjects One hundred nineteen male Sprague-Dawley rats weighing 350-385 g. Interventions Experimental traumatic brain injury of mild to moderate severity was induced using the lateral fluid percussion brain injury model in anesthetized rats (n = 89). Following traumatic brain injury, in surviving animals one group of animals was subjected to pressure-controlled hemorrhagic hypotension, maintaining the mean arterial blood pressure at 50-60 mm Hg for 30 mins (n = 47). The animals were subsequently either resuscitated with lactated Ringer’s solution (three times shed blood volume, n = 18) or left uncompensated (n = 29). Other groups of animals included those with isolated traumatic brain injury (n = 34), those with isolated hemorrhagic hypotension (n = 8), and sham-injured control animals receiving anesthesia and surgery alone (n = 22). Measurements and Main Results The withdrawal of 6-7 mL of arterial blood significantly reduced mean arterial blood pressure by 50% without decreasing arterial oxygen saturation or Pao2. Brain injury induced significant cerebral edema (p hypotension. Brain injury-induced neurologic deficits persisted up to 20 wks after injury and were also not aggravated by the hemorrhagic hypotension. Cognitive dysfunction persisted for up to 16 wks postinjury. The superimposition of hemorrhagic hypotension significantly delayed the time course of cognitive recovery

  4. Folic acid deficiency increases delayed neuronal death, DNA damage, platelet endothelial cell adhesion molecule-1 immunoreactivity, and gliosis in the hippocampus after transient cerebral ischemia.

    Science.gov (United States)

    Hwang, In Koo; Yoo, Ki-Yeon; Suh, Hong-Won; Kim, Young Sup; Kwon, Dae Young; Kwon, Young-Guen; Yoo, Jun-Hyun; Won, Moo-Ho

    2008-07-01

    Folic acid deficiency increases stroke risk. In the present study, we examined whether folic acid deficiency enhances neuronal damage and gliosis via oxidative stress in the gerbil hippocampus after transient forebrain ischemia. Animals were exposed to a folic acid-deficient diet (FAD) for 3 months and then subjected to occlusion of both common carotid arteries for 5 min. Exposure to an FAD increased plasma homocysteine levels by five- to eightfold compared with those of animals fed with a control diet (CD). In CD-treated animals, most neurons were dead in the hippocampal CA1 region 4 days after ischemia/reperfusion, whereas, in FAD-treated animals, this occurred 3 days after ischemia/reperfusion. Immunostaining for 8-hydroxy-2'-deoxyguanosine (8-OHdG) was performed to examine DNA damage in CA1 neurons in both groups after ischemia, and it was found that 8-OHdG immunoreactivity in both FAD and CD groups peaked at 12 hr after reperfusion, although the immunoreactivity in the FAD group was much greater than that in the CD group. Platelet endothelial cell adhesion molecule-1 (PECAM-1; a final mediator of neutrophil transendothelial migration) immunoreactivity in both groups increased with time after ischemia/reperfusion: Its immunoreactivity in the FAD group was much higher than that in the CD group 3 days after ischemia/reperfusion. In addition, reactive gliosis in the ischemic CA1 region increased with time after ischemia in both groups, but astrocytosis and microgliosis in the FAD group were more severe than in the CD group at all times after ischemia. Our results suggest that folic acid deficiency enhances neuronal damage induced by ischemia. 2008 Wiley-Liss, Inc.

  5. Calcium - urine

    Science.gov (United States)

    Urinary Ca+2; Kidney stones - calcium in urine; Renal calculi - calcium in your urine; Parathyroid - calcium in urine ... Urine calcium level can help your provider: Decide on the best treatment for the most common type of kidney ...

  6. Hypotonic-induced stretching of plasma membrane activates transient receptor potential vanilloid channels and sodium-calcium exchangers in mouse odontoblasts.

    Science.gov (United States)

    Sato, Masaki; Sobhan, Ubaidus; Tsumura, Maki; Kuroda, Hidetaka; Soya, Manabu; Masamura, Aya; Nishiyama, Akihiro; Katakura, Akira; Ichinohe, Tatsuya; Tazaki, Masakazu; Shibukawa, Yoshiyuki

    2013-06-01

    A number of transient receptor potential (TRP) channels have been identified as membrane-bound sensory proteins in odontoblasts. However, the activation properties of these channels remain to be clarified. The purpose of this study was to investigate hypotonic stimulation-induced Ca(2+) entry via TRP vanilloid subfamily member (TRPV) 1, TRPV2, and TRPV4 channels, which are sensitive to osmotic and mechanical stimuli, and their functional coupling with Na(+)-Ca(2+) exchangers (NCXs) in mouse odontoblast lineage cells. We examined TRP channel activity by measuring intracellular-free Ca(2+) concentration by using fura-2 fluorescence and ionic current recordings with whole-cell patch-clamp methods. Protein localization and messenger RNA expression were characterized using immunofluorescence and reverse-transcription polymerase chain reaction analyses. Extracellular hypotonic solution-induced stretching of plasma membrane resulted in the activation of Ca(2+) influx and inward currents. TRPV1, TRPV2, and TRPV4 channel antagonists inhibited the hypotonic stimulation-induced Ca(2+) entry and currents. Their respective agonists activated Ca(2+) entry. Although the increase in the intracellular free Ca(2+) concentration decayed rapidly after the applications of these TRPV channel agonists, NCX inhibitors significantly prolonged the decay time constant. The messenger RNA expression of TRPV1, TRPV2, and TRPV4 channels; NCX isoforms 2 and 3; and dentin sialophosphoprotein were up-regulated after 24 hours of exposure to the hypotonic culture medium. These results indicate that stretching of the odontoblast membrane activates TRPV1-, TRPV2-, and TRPV4-mediated Ca(2+) entry, and increased intracellular-free Ca(2+) concentration is extruded via NCXs. These results suggest that odontoblasts can act as sensors that detect stimuli applied to exposed dentin and drive a number of cellular functions including dentinogenesis and/or sensory transduction. Copyright © 2013 American

  7. Calcium Carbonate

    Science.gov (United States)

    Calcium carbonate is a dietary supplement used when the amount of calcium taken in the diet is not ... for healthy bones, muscles, nervous system, and heart. Calcium carbonate also is used as an antacid to relieve ...

  8. Calcium supplements

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/007477.htm Calcium supplements To use the sharing features on this page, please enable JavaScript. WHO SHOULD TAKE CALCIUM SUPPLEMENTS? Calcium is an important mineral for the ...

  9. In vivo analysis of the calcium signature in the plant Golgi apparatus reveals unique dynamics.

    Science.gov (United States)

    Ordenes, Viviana R; Moreno, Ignacio; Maturana, Daniel; Norambuena, Lorena; Trewavas, Anthony J; Orellana, Ariel

    2012-11-01

    The Golgi apparatus is thought to play a role in calcium homeostasis in plant cells. However, the calcium dynamics in this organelle is unknown in plants. To monitor the [Ca2+]Golgiin vivo, we obtained and analyzed Arabidopsis thaliana plants that express aequorin in the Golgi. Our results show that free [Ca2+] levels in the Golgi are higher than in the cytosol (0.70 μM vs. 0.05 μM, respectively). Stimuli such as cold shock, mechanical stimulation and hyperosmotic stress, led to a transient increase in cytosolic calcium; however, no instant change in the [Ca2+]Golgi concentration was detected. Nevertheless, a delayed increase in the [Ca2+]Golgi up to 2-3 μM was observed. Cyclopiazonic acid and thapsigargin inhibited the stimuli-induced [Ca2+]Golgi increase, suggesting that [Ca2+]Golgi levels are dependent upon the activity of Ca2+-ATPases. Treatment of these plants with the synthetic auxin analog, 2,4-dichlorophenoxy acetic acid (2,4-D), produced a slow decrease of free calcium in the organelle. Our results indicate that the plant Golgi apparatus is not involved in the generation of cytosolic calcium transients and exhibits its own dynamics modulated in part by the activity of Ca2+ pumps and hormones. Copyright © 2012 Elsevier Ltd. All rights reserved.

  10. High speed two-photon imaging of calcium dynamics in dendritic spines: consequences for spine calcium kinetics and buffer capacity

    NARCIS (Netherlands)

    Cornelisse, L.N.; van Elburg, R.A.J.; Meredith, R.M.; Yuste, R.; Mansvelder, H.D.

    2007-01-01

    Rapid calcium concentration changes in postsynaptic structures are crucial for synaptic plasticity. Thus far, the determinants of postsynaptic calcium dynamics have been studied predominantly based on the decay kinetics of calcium transients. Calcium rise times in spines in response to single action

  11. High Speed Two-Photon Imaging of Calcium Dynamics in Dendritic Spines: : Consequences for Spine Calcium Kinetics and Buffer Capacity

    NARCIS (Netherlands)

    van Elburg, R.A.J.; Cornelisse, L.N; Meredith, R.M; Yuste, R; Mansvelder, H.D

    2007-01-01

    Rapid calcium concentration changes in postsynaptic structures are crucial for synaptic plasticity. Thus far, the determinants of postsynaptic calcium dynamics have been studied predominantly based on the decay kinetics of calcium transients. Calcium rise times in spines in response to single action

  12. TRANSIENT AMORPHOUS CALCIUM PHOSPHATE IN FORMING ENAMEL

    OpenAIRE

    Beniash, Elia; Metzler, Rebecca A.; Lam, Raymond S.K.; Gilbert, P.U.P.A.

    2009-01-01

    Enamel, the hardest tissue in the body, begins as a three-dimensional network of nanometer size mineral particles, suspended in a protein gel. This mineral network serves as a template for mature enamel formation. To further understand the mechanisms of enamel formation we characterized the forming enamel mineral at an early secretory stage using x-ray absorption near-edge structure (XANES) spectromicroscopy, transmission electron microscopy (TEM), FTIR microspectroscopy and polarized light m...

  13. Psoriasis is characterized by deficient negative immune regulation compared to transient delayed-type hypersensitivity reactions [v1; ref status: indexed, http://f1000r.es/5ga

    Directory of Open Access Journals (Sweden)

    Nicholas Gulati

    2015-06-01

    Full Text Available Diphencyprone (DPCP is a hapten that causes delayed-type hypersensitivity (DTH reactions in human skin, and is used as a topical therapeutic for alopecia areata, warts, and cutaneous melanoma metastases.  We examined peak DTH reactions induced by DPCP (3 days post-challenge by comprehensive gene expression and histological analysis.  To better understand how these DTH reactions naturally resolve, we compared our DPCP biopsies to those from patients with psoriasis vulgaris, a chronic inflammatory disease that does not resolve.  By both microarray and qRT-PCR, we found that psoriasis lesional skin has significantly lower expression of many negative immune regulators compared to peak DPCP reactions.  These regulators include: interleukin-10, cytotoxic T lymphocyte-associated 4 (CTLA4, programmed cell death 1 (PD1, programmed cell death 1 ligand 1 (PDL1, programmed cell death 1 ligand 2 (PDL2, and indoleamine 2,3-dioxygenase (IDO1.  Their decreased expression was confirmed at the protein level by immunohistochemistry.  To more completely determine the balance of positive vs. negative immune regulators in both DPCP reactions and psoriasis, we developed one comprehensive gene list for positive regulatory (inflammatory genes, and another for negative regulatory (immunosuppressive genes, through Gene Ontology terms and literature review.  With this approach, we found that DPCP reactions have a higher ratio of negative to positive regulatory genes (both in terms of quantity and expression levels than psoriasis lesional skin.  These data suggest that the disease chronicity that distinguishes psoriasis from transient DTH reactions may be related to absence of negative immune regulatory pathways, and induction of these is therefore of therapeutic interest.  Further study of these negative regulatory mechanisms that are present in DPCP reactions, but not in psoriasis, could reveal novel players in the pathogenesis of chronic inflammation.  The DPCP

  14. Estimation of presynaptic calcium currents and endogenous calcium buffers at the frog neuromuscular junction with two different calcium fluorescent dyes

    Directory of Open Access Journals (Sweden)

    Dmitry eSamigullin

    2015-01-01

    Full Text Available At the frog neuromuscular junction, under physiological conditions, the direct measurement of calcium currents and of the concentration of intracellular calcium buffers—which determine the kinetics of calcium concentration and neurotransmitter release from the nerve terminal—has hitherto been technically impossible. With the aim of quantifying both Ca2+ currents and the intracellular calcium buffers, we measured fluorescence signals from nerve terminals loaded with the low-affinity calcium dye Magnesium Green or the high-affinity dye Oregon Green BAPTA-1, simultaneously with microelectrode recordings of nerve-action potentials and end-plate currents. The action-potential-induced fluorescence signals in the nerve terminals developed much more slowly than the postsynaptic response. To clarify the reasons for this observation and to define a spatiotemporal profile of intracellular calcium and of the concentration of mobile and fixed calcium buffers, mathematical modeling was employed. The best approximations of the experimental calcium transients for both calcium dyes were obtained when the calcium current had an amplitude of 1.6 ± 0.08 рА and a half-decay time of 1.2 ± 0.06 ms, and when the concentrations of mobile and fixed calcium buffers were 250 ± 13 µM and 8 ± 0.4 mM, respectively. High concentrations of endogenous buffers define the time course of calcium transients after an action potential in the axoplasm, and may modify synaptic plasticity.

  15. Compressive Transient Imaging

    KAUST Repository

    Sun, Qilin

    2017-04-01

    High resolution transient/3D imaging technology is of high interest in both scientific research and commercial application. Nowadays, all of the transient imaging methods suffer from low resolution or time consuming mechanical scanning. We proposed a new method based on TCSPC and Compressive Sensing to achieve a high resolution transient imaging with a several seconds capturing process. Picosecond laser sends a serious of equal interval pulse while synchronized SPAD camera\\'s detecting gate window has a precise phase delay at each cycle. After capturing enough points, we are able to make up a whole signal. By inserting a DMD device into the system, we are able to modulate all the frames of data using binary random patterns to reconstruct a super resolution transient/3D image later. Because the low fill factor of SPAD sensor will make a compressive sensing scenario ill-conditioned, We designed and fabricated a diffractive microlens array. We proposed a new CS reconstruction algorithm which is able to denoise at the same time for the measurements suffering from Poisson noise. Instead of a single SPAD senor, we chose a SPAD array because it can drastically reduce the requirement for the number of measurements and its reconstruction time. Further more, it not easy to reconstruct a high resolution image with only one single sensor while for an array, it just needs to reconstruct small patches and a few measurements. In this thesis, we evaluated the reconstruction methods using both clean measurements and the version corrupted by Poisson noise. The results show how the integration over the layers influence the image quality and our algorithm works well while the measurements suffer from non-trival Poisson noise. It\\'s a breakthrough in the areas of both transient imaging and compressive sensing.

  16. Presynaptic calcium dynamics of learning neurons

    OpenAIRE

    Meyer-Hermann, Michael; Erler, Frido; Soff, Gerhard

    2002-01-01

    We present a new model for the dynamics of the presynaptic intracellular calcium concentration in neurons evoked by various stimulation protocols. The aim of the model is twofold: We want to discuss the calcium transients during and after specific stimulation protocols as they are used to induce long-term-depression and long-term-potentiation. In addition we would like to provide a general tool which allows the comparison of different calcium experiments. This may help to draw conclusions on ...

  17. Calcium signals and oocyte maturation in marine invertebrates.

    Science.gov (United States)

    Deguchi, Ryusaku; Takeda, Noriyo; Stricker, Stephen A

    2015-01-01

    In various oocytes and eggs of animals, transient elevations in cytoplasmic calcium ion concentrations are known to regulate key processes during fertilization and the completion of meiosis. However, whether or not calcium transients also help to reinitiate meiotic progression at the onset of oocyte maturation remains controversial. This article summarizes reports of calcium signals playing essential roles during maturation onset (=germinal vesicle breakdown, GVBD) in several kinds of marine invertebrate oocytes. Conversely, other data from the literature, as well as previously unpublished findings for jellyfish oocytes, fail to support the view that calcium signals are required for GVBD. In addition to assessing the effects of calcium transients on GVBD in marine invertebrate oocytes, the ability of maturing oocytes to enhance their calcium-releasing capabilities after GVBD is also reviewed. Furthermore, possible explanations are proposed for the contradictory results that have been obtained regarding calcium signals during oocyte maturation in marine invertebrates.

  18. Calcium dependence of inactivation of calcium release from the sarcoplasmic reticulum in skeletal muscle fibers.

    Science.gov (United States)

    Simon, B J; Klein, M G; Schneider, M F

    1991-03-01

    The steady-state calcium dependence of inactivation of calcium release from the sarcoplasmic reticulum was studied in voltage-clamped, cut segments of frog skeletal muscle fibers containing two calcium indicators, fura-2 and anti-pyrylazo III (AP III). Fura-2 fluorescence was used to monitor resting calcium and relatively small calcium transients during small depolarizations. AP III absorbance signals were used to monitor larger calcium transients during larger depolarizations. The rate of release (Rrel) of calcium from the sarcoplasmic reticulum was calculated from the calcium transients. The equilibrium calcium dependence of inactivation of calcium release was determined using 200-ms prepulses of various amplitudes to elevate [Ca2+] to various steady levels. Each prepulse was followed by a constant test pulse. The suppression of peak Rrel during the test pulse provided a measure of the extent of inactivation of release at the end of the prepulse. The [Ca2+] dependence of inactivation indicated that binding of more than one calcium ion was required to inactivate each release channel. Half-maximal inactivation was produced at a [Ca2+] of approximately 0.3 microM. Variation of the prepulse duration and amplitude showed that the suppression of peak release was consistent with calcium-dependent inactivation of calcium release but not with calcium depletion. The same calcium dependence of inactivation was obtained using different amplitude test pulses to determine the degree of inactivation. Prepulses that produced near maximal inactivation of release during the following test pulse produced no suppression of intramembrane charge movement during the test pulse, indicating that inactivation occurred at a step beyond the voltage sensor for calcium release. Three alternative set of properties that were assumed for the rapidly equilibrating calcium-binding sites intrinsic to the fibers gave somewhat different Rrel records, but gave very similar calcium dependence of

  19. Calcium currents in a fast-twitch skeletal muscle of the rat.

    Science.gov (United States)

    Donaldson, P L; Beam, K G

    1983-10-01

    Slow ionic currents were measured in the rat omohyoid muscle with the three-microelectrode voltage-clamp technique. Sodium and delayed rectifier potassium currents were blocked pharmacologically. Under these conditions, depolarizing test pulses elicited an early outward current, followed by a transient slow inward current, followed in turn by a late outward current. The early outward current appeared to be a residual delayed rectifier current. The slow inward current was identified as a calcium current on the basis that (a) its magnitude depended on extracellular calcium concentration, (b) it was blocked by the addition of the divalent cations cadmium or nickel, and reduced in magnitude by the addition of manganese or cobalt, and (c) barium was able to replace calcium as an inward current carrier. The threshold potential for inward calcium current was around -20 mV in 10mM extracellular calcium and about -35 mV in 2 mM calcium. Currents were net inward over part of their time course for potentials up to at least +30 mV. At temperatures of 20-26 degrees C, the peak inward current (at approximately 0 mV) was 139 +/- 14 microA/cm2 (mean +/- SD), increasing to 226 +/- 28 microA/cm2 at temperatures of 27-37 degrees C. The late outward current exhibited considerable fiber-to-fiber variability. In some fibers it was primarily a time-independent, nonlinear leakage current. In other fibers it was primarily a time-independent, nonlinear leakage current. In other fibers it appeared to be the sum of both leak and a slowly activated outward current. The rate of activation of inward calcium current was strongly temperature dependent. For example, in a representative fiber, the time-to-peak inward current for a +10-mV test pulse decreased from approximately 250 ms at 20 degrees C to 100 ms at 30 degrees C. At 37 degrees C, the time-to-peak current was typically approximately 25 ms. The earliest phase of activation was difficult to quantify because the ionic current was partially

  20. Delayed Puberty

    DEFF Research Database (Denmark)

    Kolby, Nanna; Busch, Alexander Siegfried; Juul, Anders

    2017-01-01

    Delayed puberty can be a source of great concern and anxiety, although it usually is caused by a self-limiting variant of the normal physiological timing named constitutional delay of growth and puberty (CDGP). Delayed puberty can, however, also be the first presentation of a permanent condition...... of diagnostic evaluation today remain in distinguishing the benign CDGP from underlying pathological causes such as hypogonadotropic hypogonadism (HH) and hypergonadotropic hypogonadism. Several techniques have been investigated for this purpose and are reviewed in this chapter; however, no single test is yet...

  1. Yeast respond to hypotonic shock with a calcium pulse

    Science.gov (United States)

    Batiza, A. F.; Schulz, T.; Masson, P. H.

    1996-01-01

    We have used the transgenic AEQUORIN calcium reporter system to monitor the cytosolic calcium ([Ca2+]cyt) response of Saccharomyces cerevisiae to hypotonic shock. Such a shock generates an almost immediate and transient rise in [Ca2+]cyt which is eliminated by gadolinium, a blocker of stretch-activated channels. In addition, this transient rise in [Ca2+]cyt is initially insensitive to 1,2-bis-(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA), an extracellular calcium chelator. However, BAPTA abruptly attenuates the maintenance of that transient rise. These data show that hypotonic shock generates a stretch-activated channel-dependent calcium pulse in yeast. They also suggest that the immediate calcium influx is primarily generated from intracellular stores, and that a sustained increase in [Ca2+]cyt depends upon extracellular calcium.

  2. Influence of sodium borate on the early age hydration of calcium sulfoaluminate cement

    Energy Technology Data Exchange (ETDEWEB)

    Champenois, Jean-Baptiste; Dhoury, Mélanie [CEA, DEN, DTCD, SPDE, F-30207 Bagnols-sur-Cèze Cedex (France); Cau Dit Coumes, Céline, E-mail: celine.cau-dit-coumes@cea.fr [CEA, DEN, DTCD, SPDE, F-30207 Bagnols-sur-Cèze Cedex (France); Mercier, Cyrille [LMCPA, Université de Valenciennes et du Hainaut Cambrésis, 59600 Maubeuge (France); Revel, Bertrand [Centre Commun de Mesure RMN, Université Lille1 Sciences Technologies, Cité Scientifique, 59655 Villeneuve d' Ascq Cedex (France); Le Bescop, Patrick [CEA, DEN, DPC, SECR, F-91192 Gif-sur-Yvette (France); Damidot, Denis [Ecole des Mines de Douai, LGCgE-GCE, 59508 Douai (France)

    2015-04-15

    Calcium sulfoaluminate (CSA) cements are potential candidates for the conditioning of radioactive wastes with high sodium borate concentrations. This work thus investigates early age hydration of two CSA cements with different gypsum contents (0 to 20%) as a function of the mixing solution composition (borate and NaOH concentrations). Gypsum plays a key role in controlling the reactivity of cement. When the mixing solution is pure water, increasing the gypsum concentration accelerates cement hydration. However, the reverse is observed when the mixing solution contains sodium borate. Until gypsum exhaustion, the pore solution pH remains constant at ~ 10.8, and a poorly crystallized borate compound (ulexite) precipitates. A correlation is established between this transient precipitation and the hydration delay. Decreasing the gypsum content in the binder, or increasing the sodium content in the mixing solution, are two ways of reducing the stability of ulexite, thus decreasing the hydration delay.

  3. Delayed growth

    Science.gov (United States)

    ... 4 years Developmental milestones record - 5 years Causes Constitutional growth delay refers to children who are small ... nutrition expert who can help you choose the right foods to offer your child. What to Expect ...

  4. Delayed Ejaculation

    Science.gov (United States)

    ... bladder rather than out of the penis Psychological causes of delayed ejaculation include: Depression, anxiety or other mental health conditions Relationship problems due to stress, poor communication or other concerns ...

  5. Delayed Ejaculation

    Science.gov (United States)

    ... of stress Delayed ejaculation Symptoms & causes Diagnosis & treatment Advertisement Mayo Clinic does not endorse companies or products. ... a Job Site Map About This Site Twitter Facebook Google YouTube Pinterest Mayo Clinic is a not- ...

  6. Reactor transient

    Energy Technology Data Exchange (ETDEWEB)

    Menegus, R.L.

    1956-05-31

    The authors are planning a calculation to be done on the Univac at the Louviers Building to estimate the effect of xenon transients, a high reactor power. This memorandum outlines the reasons why they prefer to do the work at Louviers rather than at another location, such as N.Y.U. They are to calculate the response of the reactor to a sudden change in position of the half rods. Qualitatively, the response will be a change in the rooftop ratio of the neutron flux. The rooftop ratio may oscillate with high damping, or, instead, it may oscillate for many cycles. It has not been possible for them to determine this response by hand calculation because of the complexity of the problem, and yet it is important for them to be certain that high power operation will not lead us to inherently unstable operation. Therefore they have resorted to machine computation. The system of differential equations that describes the response has seven dependent variables; therefore there are seven equations, each coupled with one or more of the others. The authors have discussed the problem with R.R. Haefner at the plant, and it is his opinion that the IBM 650 cannot adequately handle the system of seven equations because the characteristic time constants vary over a range of about 10{sup 8}. The Univac located at the Louviers Building is said to be satisfactory for this computation.

  7. Transient tachypnea - newborn

    Science.gov (United States)

    TTN; Wet lungs - newborns; Retained fetal lung fluid; Transient RDS; Prolonged transition; Neonatal - transient tachypnea ... Newborns with transient tachypnea have breathing problems soon after birth, most often within 1 to 2 hours. ...

  8. Transient outward current modulates discontinuous conduction in rabbit ventricular cell pairs.

    Science.gov (United States)

    Huelsing, D J; Pollard, A E; Spitzer, K W

    2001-03-01

    While several studies have demonstrated that the L-type calcium current maintains discontinuous conduction, the contribution of the transient outward current (I(to)) to conduction remains unclear. This study evaluated the effects of I(to) inhibition on conduction between ventricular myocytes. An electronic circuit with a variable resistance (R(j)) was used to electrically couple single epicardial myocytes isolated from rabbit right ventricle. We inhibited I(to) with 4-aminopyridine superfusion, rate-acceleration, or premature stimulation to evaluate the subsequent effects on conduction delay and the critical R(j), which was quantified as the highest R(j) that could be imposed before conduction failed. I(to) inhibition significantly enhanced conduction in all cell pairs (n=23). Pharmacologic inhibition of I(to) resulted in a 32+/-5% decrease in conduction delay and a 36+/-7% increase in critical R(j). Similarly, reduction of the basic cycle length from 2 to 0.5 s resulted in a 31+/-3% decrease in conduction delay and a 31+/-3% increase in critical R(j). Finally, premature action potentials conducted with a 41+/-4% shorter conduction delay and a 73+/-24% higher critical R(j) than basic action potentials. I(to) inhibition significantly enhanced conduction across high R(j). These results suggest I(to) may contribute to rate-dependent conduction abnormalities.

  9. Calcium Electroporation

    DEFF Research Database (Denmark)

    Frandsen, Stine Krog; Gibot, Laure; Madi, Moinecha

    2015-01-01

    BACKGROUND: Calcium electroporation describes the use of high voltage electric pulses to introduce supraphysiological calcium concentrations into cells. This promising method is currently in clinical trial as an anti-cancer treatment. One very important issue is the relation between tumor cell kill...... efficacy-and normal cell sensitivity. METHODS: Using a 3D spheroid cell culture model we have tested the effect of calcium electroporation and electrochemotherapy using bleomycin on three different human cancer cell lines: a colorectal adenocarcinoma (HT29), a bladder transitional cell carcinoma (SW780......), and a breast adenocarcinoma (MDA-MB231), as well as on primary normal human dermal fibroblasts (HDF-n). RESULTS: The results showed a clear reduction in spheroid size in all three cancer cell spheroids three days after treatment with respectively calcium electroporation (p

  10. Delayed fluorescence in photosynthesis.

    Science.gov (United States)

    Goltsev, Vasilij; Zaharieva, Ivelina; Chernev, Petko; Strasser, Reto J

    2009-01-01

    Photosynthesis is a very efficient photochemical process. Nevertheless, plants emit some of the absorbed energy as light quanta. This luminescence is emitted, predominantly, by excited chlorophyll a molecules in the light-harvesting antenna, associated with Photosystem II (PS II) reaction centers. The emission that occurs before the utilization of the excitation energy in the primary photochemical reaction is called prompt fluorescence. Light emission can also be observed from repopulated excited chlorophylls as a result of recombination of the charge pairs. In this case, some time-dependent redox reactions occur before the excitation of the chlorophyll. This delays the light emission and provides the name for this phenomenon-delayed fluorescence (DF), or delayed light emission (DLE). The DF intensity is a decreasing polyphasic function of the time after illumination, which reflects the kinetics of electron transport reactions both on the (electron) donor and the (electron) acceptor sides of PS II. Two main experimental approaches are used for DF measurements: (a) recording of the DF decay in the dark after a single turnover flash or after continuous light excitation and (b) recording of the DF intensity during light adaptation of the photosynthesizing samples (induction curves), following a period of darkness. In this paper we review historical data on DF research and recent advances in the understanding of the relation between the delayed fluorescence and specific reactions in PS II. An experimental method for simultaneous recording of the induction transients of prompt and delayed chlorophyll fluorescence and decay curves of DF in the millisecond time domain is discussed.

  11. Voltage-gated calcium flux mediatesEscherichia colimechanosensation.

    Science.gov (United States)

    Bruni, Giancarlo N; Weekley, R Andrew; Dodd, Benjamin J T; Kralj, Joel M

    2017-08-29

    Electrically excitable cells harness voltage-coupled calcium influx to transmit intracellular signals, typically studied in neurons and cardiomyocytes. Despite intense study in higher organisms, investigations of voltage and calcium signaling in bacteria have lagged due to their small size and a lack of sensitive tools. Only recently were bacteria shown to modulate their membrane potential on the timescale of seconds, and little is known about the downstream effects from this modulation. In this paper, we report on the effects of electrophysiology in individual bacteria. A genetically encoded calcium sensor expressed in Escherichia coli revealed calcium transients in single cells. A fusion sensor that simultaneously reports voltage and calcium indicated that calcium influx is induced by voltage depolarizations, similar to metazoan action potentials. Cytoplasmic calcium levels and transients increased upon mechanical stimulation with a hydrogel, and single cells altered protein concentrations dependent on the mechanical environment. Blocking voltage and calcium flux altered mechanically induced changes in protein concentration, while inducing calcium flux reproduced these changes. Thus, voltage and calcium relay a bacterial sense of touch and alter cellular lifestyle. Although the calcium effectors remain unknown, these data open a host of new questions about E. coli , including the identity of the underlying molecular players, as well as other signals conveyed by voltage and calcium. These data also provide evidence that dynamic voltage and calcium exists as a signaling modality in the oldest domain of life, and therefore studying electrophysiology beyond canonical electrically excitable cells could yield exciting new findings.

  12. An attempt to induce transient immunosuppression pre-erythrocytapheresis in a girl with sickle cell disease, a history of severe delayed hemolytic transfusion reactions and need for hip prosthesis

    Directory of Open Access Journals (Sweden)

    Alessandro Cattoni

    2013-06-01

    Full Text Available We report on a case of delayed hemolytic transfusion reaction (DHTR occurred 7 days after an erythrocytapheresis or eritroexchange procedure (EEX treated with rituximab and glucocorticoids in a 15-years old patient with sickle cell disease. EEX was performed despite a previous diagnosis of alloimmunization, in order to reduce hemoglobin S rate before a major surgery for avascular necrosis of the femoral head. A first dose of rituximab was administered before EEX. However, rituximab couldn’t prevent DHTR that occurred with acute hemolysis, hemoglobinuria and hyper-bilirubinemia. A further dose of rituximab and three boli of methylprednisolone were given after the onset of the reaction. It is likely that the combined use of rituximab and steroids managed to gradually improve both patient’s general conditions and hemoglobin levels. Nor early or late side effects were registered in a 33-months follow-up period. This report suggests the potential effectiveness and safety of rituximab in combination with steroids in managing and mitigating the symptoms of delayed post-transfusional hemolytic reactions in alloimmunized patients affected by sickle cell disease with absolute need for erythrocytapheresis.

  13. Teriparatide Induced Delayed Persistent Hypercalcemia

    Directory of Open Access Journals (Sweden)

    Nirosshan Thiruchelvam

    2014-01-01

    Full Text Available Teriparatide, a recombinant PTH, is an anabolic treatment for osteoporosis that increases bone density. Transient hypercalcemia is a reported side effect of teriparatide that is seen few hours following administration of teriparatide and resolves usually within 16 hours of drug administration. Persistent hypercalcemia, although not observed in clinical trials, is rarely reported. The current case describes a rare complication of teriparatide induced delayed persistent hypercalcemia.

  14. Local perinuclear calcium signals associated with mitosis-entry in early sea urchin embryos

    OpenAIRE

    1996-01-01

    Using calcium-sensitive dyes together with their dextran conjugates and confocal microscopy, we have looked for evidence of localized calcium signaling in the region of the nucleus before entry into mitosis, using the sea urchin egg first mitotic cell cycle as a model. Global calcium transients that appear to originate from the nuclear area are often observed just before nuclear envelope breakdown (NEB). In the absence of global increases in calcium, confocal microscopy using Calcium Green- 1...

  15. Spatiotemporal intracellular calcium dynamics during cardiac alternans

    Science.gov (United States)

    Restrepo, Juan G.; Karma, Alain

    2009-09-01

    Cellular calcium transient alternans are beat-to-beat alternations in the peak cytosolic calcium concentration exhibited by cardiac cells during rapid electrical stimulation or under pathological conditions. Calcium transient alternans promote action potential duration alternans, which have been linked to the onset of life-threatening ventricular arrhythmias. Here we use a recently developed physiologically detailed mathematical model of ventricular myocytes to investigate both stochastic and deterministic aspects of intracellular calcium dynamics during alternans. The model combines a spatially distributed description of intracellular calcium cycling, where a large number of calcium release units are spatially distributed throughout the cell, with a full set of ionic membrane currents. The results demonstrate that ion channel stochasticity at the level of single calcium release units can influence the whole-cell alternans dynamics by causing phase reversals over many beats during fixed frequency pacing close to the alternans bifurcation. They also demonstrate the existence of a wide range of dynamical states. Depending on the sign and magnitude of calcium-voltage coupling, calcium alternans can be spatially synchronized or desynchronized, in or out of phase with action potential duration alternans, and the node separating out-of-phase regions of calcium alternans can be expelled from or trapped inside the cell. This range of states is found to be larger than previously anticipated by including a robust global attractor where calcium alternans can be spatially synchronized but out of phase with action potential duration alternans. The results are explained by a combined theoretical analysis of alternans stability and node motion using general iterative maps of the beat-to-beat dynamics and amplitude equations.

  16. Current interruption transients calculation

    CERN Document Server

    Peelo, David F

    2014-01-01

    Provides an original, detailed and practical description of current interruption transients, origins, and the circuits involved, and how they can be calculated Current Interruption Transients Calculationis a comprehensive resource for the understanding, calculation and analysis of the transient recovery voltages (TRVs) and related re-ignition or re-striking transients associated with fault current interruption and the switching of inductive and capacitive load currents in circuits. This book provides an original, detailed and practical description of current interruption transients, origins,

  17. Delayed Puberty

    DEFF Research Database (Denmark)

    Kolby, Nanna; Busch, Alexander Siegfried; Juul, Anders

    2017-01-01

    or a symptom of an underlying disease. The diagnosis delayed puberty is made if there are no signs of puberty at an age corresponding to 2 SD above the population mean age at pubertal onset, often translated into 14 years in boys. Delayed puberty among boys is a frequent presentation in pediatrics....... The underlying reasons for the large variation in the age at pubertal onset are not fully established; however, nutritional status and socioeconomic and environmental factors are known to be influencing, and a significant amount of influencing genetic factors have also been identified. The challenges...... of diagnostic evaluation today remain in distinguishing the benign CDGP from underlying pathological causes such as hypogonadotropic hypogonadism (HH) and hypergonadotropic hypogonadism. Several techniques have been investigated for this purpose and are reviewed in this chapter; however, no single test is yet...

  18. Store-operated calcium entry is essential for glial calcium signalling in CNS white matter.

    Science.gov (United States)

    Papanikolaou, M; Lewis, A; Butt, A M

    2017-02-28

    'Calcium signalling' is the ubiquitous response of glial cells to multiple extracellular stimuli. The primary mechanism of glial calcium signalling is by release of calcium from intracellular stores of the endoplasmic reticulum (ER). Replenishment of ER Ca(2+) stores relies on store-operated calcium entry (SOCE). However, despite the importance of calcium signalling in glial cells, little is known about their mechanisms of SOCE. Here, we investigated SOCE in glia of the mouse optic nerve, a typical CNS white matter tract that comprises bundles of myelinated axons and the oligodendrocytes and astrocytes that support them. Using quantitative RT-PCR, we identified Orai1 channels, both Stim1 and Stim2, and the transient receptor potential M3 channel (TRPM3) as the primary channels for SOCE in the optic nerve, and their expression in both astrocytes and oligodendrocytes was demonstrated by immunolabelling of optic nerve sections and cultures. The functional importance of SOCE was demonstrated by fluo-4 calcium imaging on isolated intact optic nerves and optic nerve cultures. Removal of extracellular calcium ([Ca(2+)]o) resulted in a marked depletion of glial cytosolic calcium ([Ca(2+)]i), which recovered rapidly on restoration of [Ca(2+)]o via SOCE. 2-aminoethoxydiphenylborane (2APB) significantly decreased SOCE and severely attenuated ATP-mediated calcium signalling. The results provide evidence that Orai/Stim and TRPM3 are important components of the 'calcium toolkit' that underpins SOCE and the sustainability of calcium signalling in white matter glia.

  19. Get Enough Calcium

    Science.gov (United States)

    ... Calcium Print This Topic En español Get Enough Calcium Browse Sections The Basics Overview Foods and Vitamins ... women, don't get enough calcium. How much calcium do I need every day? Women: If you ...

  20. Calcium carbonate overdose

    Science.gov (United States)

    Tums overdose; Calcium overdose ... Calcium carbonate can be dangerous in large amounts. ... Some products that contain calcium carbonate are certain: ... and mineral supplements Other products may also contain calcium ...

  1. The spatial pattern of atrial cardiomyocyte calcium signalling modulates contraction.

    Science.gov (United States)

    Mackenzie, Lauren; Roderick, H Llewelyn; Berridge, Michael J; Conway, Stuart J; Bootman, Martin D

    2004-12-15

    We examined the regulation of calcium signalling in atrial cardiomyocytes during excitation-contraction coupling, and how changes in the distribution of calcium impacts on contractility. Under control conditions, calcium transients originated in subsarcolemmal locations and showed local regeneration through activation of calcium-induced calcium release from ryanodine receptors. Despite functional ryanodine receptors being expressed at regular (approximately 2 microm) intervals throughout atrial myocytes, the subsarcolemmal calcium signal did not spread in a fully regenerative manner through the interior of a cell. Rather, there was a diminishing centripetal propagation of calcium. The lack of regeneration was due to mitochondria and SERCA pumps preventing the inward movement of calcium. Inhibiting these calcium buffering mechanisms allowed the globalisation of action potential-evoked responses. In addition, physiological positive inotropic agents, such as endothelin-1 and beta-adrenergic agonists, as well as enhanced calcium current, calcium store loading and inositol 1,4,5-trisphosphate infusion also led to regenerative global responses. The consequence of globalising calcium signals was a significant increase in cellular contraction. These data indicate how calcium signals and their consequences are determined by the interplay of multiple subcellular calcium management systems.

  2. Transient Global Amnesia

    Science.gov (United States)

    ... sudden memory loss. Request an Appointment at Mayo Clinic Causes The underlying cause of transient global amnesia is unknown. There appears to be a link between transient global amnesia and a history of migraines, though the underlying factors that contribute ...

  3. Endoplasmic reticulum generates calcium signalling microdomains around the nucleus and spindle in syncytial Drosophila embryos.

    Science.gov (United States)

    Parry, H; McDougall, A; Whitaker, M

    2006-06-01

    Cell cycle calcium signals are generated by inositol trisphosphate-mediated release of calcium from internal stores [Ciapa, Pesando, Wilding and Whitaker (1994) Nature (London) 368, 875-878; Groigno and Whitaker (1998) Cell 92, 193-204]. The major internal calcium store is the ER (endoplasmic reticulum): the spatial organization of the ER during mitosis is important in defining a microdomain around the nucleus and mitotic spindle in early Drosophila embryos [Parry, McDougall and Whitaker (2005) J. Cell Biol. 171, 47-59]. Nuclear divisions in syncytial Drosophila embryos are accompanied by both cortical and nuclear localized calcium transients. Mitosis is prevented by the InsP(3) antagonists Xestospongin C and heparin. Nuclear-localized transients and cortical transients rely on extraembryonic calcium, suggesting that ER calcium levels are maintained by calcium influx.

  4. The control of calcium signaling in the heart | Eisner | Journal of ...

    African Journals Online (AJOL)

    Work on the role of calcium in the heart began in the nineteenth century with Ringer's demonstration that calcium is essential for cardiac contraction. This article provides a brief overview of the regulation of cardiac calcium signalling. Contraction results from the systolic rise of Ca concentration (the Ca transient). This occurs ...

  5. Transient drainage summary report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-09-01

    This report summarizes the history of transient drainage issues on the Uranium Mill Tailings Remedial Action (UMTRA) Project. It defines and describes the UMTRA Project disposal cell transient drainage process and chronicles UMTRA Project treatment of the transient drainage phenomenon. Section 4.0 includes a conceptual cross section of each UMTRA Project disposal site and summarizes design and construction information, the ground water protection strategy, and the potential for transient drainage.

  6. PSH Transient Simulation Modeling

    Energy Technology Data Exchange (ETDEWEB)

    Muljadi, Eduard [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

    2017-12-21

    PSH Transient Simulation Modeling presentation from the WPTO FY14 - FY16 Peer Review. Transient effects are an important consideration when designing a PSH system, yet numerical techniques for hydraulic transient analysis still need improvements for adjustable-speed (AS) reversible pump-turbine applications.

  7. Transient Ischemic Attack

    Medline Plus

    Full Text Available Transient Ischemic Attack TIA , or transient ischemic attack, is a "mini stroke" that occurs when a blood clot blocks an artery for a short time. The only ... TIA is that with TIA the blockage is transient (temporary). TIA symptoms occur rapidly and last a ...

  8. Homer regulates calcium signalling in growth cone turning

    Directory of Open Access Journals (Sweden)

    Thompson Michael JW

    2009-08-01

    Full Text Available Abstract Background Homer proteins are post-synaptic density proteins with known functions in receptor trafficking and calcium homeostasis. While they are key mediators of synaptic plasticity, they are also known to function in axon guidance, albeit by mechanisms that are yet to be elucidated. Homer proteins couple extracellular receptors – such as metabotropic glutamate receptors and the transient receptor potential canonical family of cation channels – to intracellular receptors such as inositol triphosphate and ryanodine receptors on intracellular calcium stores and, therefore, are well placed to regulate calcium dynamics within the neural growth cone. Here we used growth cones from dorsal root ganglia, a well established model in the field of axon guidance, and a growth cone turning assay to examine Homer1 function in axon guidance. Results Homer1 knockdown reversed growth cone turning from attraction to repulsion in response to the calcium-dependent guidance cues brain derived neurotrophic factor and netrin-1. Conversely, Homer1 knockdown had no effect on repulsion to the calcium-independent guidance cue Semaphorin-3A. This reversal of attractive turning suggested a requirement for Homer1 in a molecular switch. Pharmacological experiments confirmed that the operational state of a calcium-calmodulin dependent protein kinase II/calcineurin phosphatase molecular switch was dependent on Homer1 expression. Calcium imaging of motile growth cones revealed that Homer1 is required for guidance-cue-induced rise of cytosolic calcium and the attenuation of spontaneous cytosolic calcium transients. Homer1 knockdown-induced calcium transients and turning were inhibited by antagonists of store-operated channels. In addition, immunocytochemistry revealed the close association of Homer1 with the store-operated proteins TRPC1 and STIM1 within dorsal root ganglia growth cones. Conclusion These experiments provide evidence that Homer1 is an essential

  9. Transient combustion in hybrid rockets

    Science.gov (United States)

    Karabeyoglu, Mustafa Arif

    1998-09-01

    Hybrid rockets regained interest recently as an alternative chemical propulsion system due to their advantages over the solid and liquid systems that are currently in use. Development efforts on hybrids revealed two important problem areas: (1) low frequency instabilities and (2) slow transient response. Both of these are closely related to the transient behavior which is a poorly understood aspect of hybrid operation. This thesis is mainly involved with a theoretical study of transient combustion in hybrid rockets. We follow the methodology of identifying and modeling the subsystems of the motor such as the thermal lags in the solid, boundary layer combustion and chamber gasdynamics from a dynamic point of view. We begin with the thermal lag in the solid which yield the regression rate for any given wall heat flux variation. Interesting phenomena such as overshooting during throttling and the amplification and phase lead regions in the frequency domain are discovered. Later we develop a quasi-steady transient hybrid combustion model supported with time delays for the boundary layer processes. This is integrated with the thermal lag system to obtain the thermal combustion (TC) coupled response. The TC coupled system with positive delays generated low frequency instabilities. The scaling of the instabilities are in good agreement with actual motor test data. Finally, we formulate a gasdynamic model for the hybrid chamber which successfully resolves the filling/emptying and longitudinal acoustic behavior of the motor. The TC coupled system is later integrated to the gasdynamic model to obtain the overall response (TCG coupled system) of gaseous oxidizer motors with stiff feed systems. Low frequency instabilities were also encountered for the TCG coupled system. Apart from the transient investigations, the regression rate behavior of liquefying hybrid propellants such as solid cryogenic materials are also studied. The theory is based on the possibility of enhancement

  10. Calcium paradox and calcium entry blockers

    NARCIS (Netherlands)

    Ruigrok, T.J.C.; Slade, A.M.; Nayler, W.G.; Meijler, F.L.

    1984-01-01

    Reperfusion of isolated hearts with calcium-containing solution after a short period of calcium-free perfusion results in irreversible cell damage (calcium paradox). This phenomenon is characterized by an excessive influx of calcium into the cells, the rapid onset of myocardial contracture,

  11. Time course of activation of calcium release from sarcoplasmic reticulum in skeletal muscle.

    Science.gov (United States)

    Simon, B J; Schneider, M F

    1988-12-01

    Myoplasmic free calcium transients were measured with antipyrylazo III in voltage clamped segments of frog skeletal muscle fibers and were used to calculate the rate of release (Rrel) of calcium from the sarcoplasmic reticulum. Intramembrane charge movement was measured for the same pulses in the same fibers. During a depolarizing pulse Rrel rose to an early peak and then decayed relatively rapidly but incompletely due to calcium-dependent inactivation (Schneider M.F., and B.J. Simon. 1988. J. Physiol. (Lond.). 405:727-745). Two approaches were used to determine release activation independent of the effects of inactivation: (a) a mathematical correction based on the assumption that inactivation was a process occurring in parallel with and independently of activation; (b) an experimental procedure in which release was maximally inactivated by a large short prepulse and then the remaining noninactivatable component of release was monitored during a subsequent test pulse. Both procedures gave the same time course of activation of release. Release activation paralleled the time course of intramembrane charge movement but was delayed by a few milliseconds.

  12. Normal and malignant cells exhibit differential responses to calcium electroporation

    DEFF Research Database (Denmark)

    Frandsen, Stine Krog; Krüger, Mie Barthold; Mangalanathan, Uma M.

    2017-01-01

    Calcium electroporation may offer a simple general tool for anticancer therapy. Transient permeabilization of cancer cell membranes created by applying short, high-voltage pulses in tumors enables high calcium influxes that trigger cell death. In this study, we compared the relative sensitivity...... of different human tumor models and normal tissues to calcium electroporation. Plasma membrane Ca(2+)-ATPase (PMCA) protein expression was confirmed in vitro in all cancer cell lines and normal primary dermal fibroblasts studied. In all tumor types tested in vivo, calcium electroporation effectively induced...... tissue after calcium electroporation but decreased in skin tissue 4 hours after treatment to levels comparable with untreated controls, whereas calcium content endured at high levels in tumor tissue. Mechanistic experiments in vitro indicated that calcium influx was similar in fibroblasts and cancer...

  13. Tuning local calcium availability: cell-type-specific immobile calcium buffer capacity in hippocampal neurons.

    Science.gov (United States)

    Matthews, Elizabeth A; Schoch, Susanne; Dietrich, Dirk

    2013-09-04

    It has remained difficult to ascribe a specific functional role to immobile or fixed intracellular calcium buffers in central neurons because the amount of these buffers is unknown. Here, we explicitly isolated the fixed buffer fraction by prolonged whole-cell patch-clamp dialysis and quantified its buffering capacity in murine hippocampal slices using confocal calcium imaging and the "added-buffer" approach. In dentate granule cells, the calcium binding ratio (κ) after complete washout of calbindin D28k (Cb), κfixed, displayed a substantial value of ∼100. In contrast, in CA1 oriens lacunosum moleculare (OLM) interneurons, which do not contain any known calcium-binding protein(s), κfixed amounted to only ∼30. Based on these values, a theoretical analysis of dendritic spread of calcium after local entry showed that fixed buffers, in the absence of mobile species, decrease intracellular calcium mobility 100- and 30-fold in granule cells and OLM cells, respectively, and thereby strongly slow calcium signals. Although the large κfixed alone strongly delays the spread of calcium in granule cells, this value optimizes the benefits of additionally expressing the mobile calcium binding protein Cb. With such high κfixed, Cb effectively increases the propagation velocity to levels seen in OLM cells and, contrary to expectation, does not affect the peak calcium concentration close to the source but sharpens the spatial and temporal calcium gradients. The data suggest that the amount of fixed buffers determines the temporal availability of calcium for calcium-binding partners and plays a pivotal role in setting the repertoire of cellular calcium signaling regimens.

  14. The effect of calcium on auxin depletion-induced tomato ...

    African Journals Online (AJOL)

    Indole-3-acetic acid (IAA) and calcium are the most important factors that instigate plant organ abscission. This study aimed to elucidate the mechanisms that underlie the effects of IAA and calcium on delayed abscission in tomato. The results showed a clear trend towards reduced abscission rates with increased ...

  15. Coronary Calcium Scan

    Science.gov (United States)

    ... Back To Health Topics / Coronary Calcium Scan Coronary Calcium Scan Also known as Calcium Scan Test A coronary calcium scan is a CT scan of your heart that detects and measures the amount of calcium in the walls of your coronary arteries. Overview ...

  16. Exploring transient detection with WFI onboard Athena

    Science.gov (United States)

    Pradhan, Pragati; Kennea, Jamie; Falcone, Abraham; Burrows, David N.

    2018-01-01

    X-ray transients are among the most enigmatic objects in the cosmic sky. The unpredictability of their transient behaviour has been a study of much interest in the recent years. While significant progress has been made in this direction, a more complete understanding of such events is often hampered by the delay in the rapid follow-up of any transient event. An efficient way to mitigate this constraint would be to devise a way for onboard detection of such transient phenomenon. The Wide Field Imager (WFI), which is a part of the upcoming X-ray mission Athena, with its 40' X 40' field of view can add some valuable contribution to this In this work, we aim to discuss an algorithm for the on-board detection of X-ray transients with WFI. We will also present a few test cases for the feasibility test of that algorithm on Swift-XRT data. Finally, we discuss what type of X-ray transients are best suited for onboard detection from WFI, their probability of detections and the useful science that can follow.

  17. Calcium source (image)

    Science.gov (United States)

    Getting enough calcium to keep bones from thinning throughout a person's life may be made more difficult if that person has ... as a tendency toward kidney stones, for avoiding calcium-rich food sources. Calcium deficiency also effects the ...

  18. Calcium and bones (image)

    Science.gov (United States)

    Calcium is one of the most important minerals for the growth, maintenance, and reproduction of the human ... body, are continually being re-formed and incorporate calcium into their structure. Calcium is essential for the ...

  19. Calcium hydroxide poisoning

    Science.gov (United States)

    Hydrate - calcium; Lime milk; Slaked lime ... Calcium hydroxide ... These products contain calcium hydroxide: Cement Limewater Many industrial solvents and cleaners (hundreds to thousands of construction products, flooring strippers, brick cleaners, cement ...

  20. Calcium Pyrophosphate Deposition (CPPD)

    Science.gov (United States)

    ... Patient / Caregiver Diseases & Conditions Calcium Pyrophosphate Deposition (CPPD) Calcium Pyrophosphate Deposition (CPPD) Fast Facts The risk of ... young people, too. Proper diagnosis depends on detecting calcium pyrophosphate crystals in the fluid of an affected ...

  1. Calcium blood test

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/003477.htm Calcium blood test To use the sharing features on this page, please enable JavaScript. The calcium blood test measures the level of calcium in the blood. ...

  2. Intracellular sphingosine releases calcium from lysosomes

    Science.gov (United States)

    Höglinger, Doris; Haberkant, Per; Aguilera-Romero, Auxiliadora; Riezman, Howard; Porter, Forbes D; Platt, Frances M; Galione, Antony; Schultz, Carsten

    2015-01-01

    To elucidate new functions of sphingosine (Sph), we demonstrate that the spontaneous elevation of intracellular Sph levels via caged Sph leads to a significant and transient calcium release from acidic stores that is independent of sphingosine 1-phosphate, extracellular and ER calcium levels. This photo-induced Sph-driven calcium release requires the two-pore channel 1 (TPC1) residing on endosomes and lysosomes. Further, uncaging of Sph leads to the translocation of the autophagy-relevant transcription factor EB (TFEB) to the nucleus specifically after lysosomal calcium release. We confirm that Sph accumulates in late endosomes and lysosomes of cells derived from Niemann-Pick disease type C (NPC) patients and demonstrate a greatly reduced calcium release upon Sph uncaging. We conclude that sphingosine is a positive regulator of calcium release from acidic stores and that understanding the interplay between Sph homeostasis, calcium signaling and autophagy will be crucial in developing new therapies for lipid storage disorders such as NPC. DOI: http://dx.doi.org/10.7554/eLife.10616.001 PMID:26613410

  3. Dysgraphia in Children: Lasting Psychomotor Deficiency or Transient Developmental Delay?

    Science.gov (United States)

    Smits-Engelsman, Bouwien C. M.; Van Galen, Gerard P.

    1997-01-01

    Used writing tasks recorded on a computer-monitored XY tablet to differentiate between normal variations in psychomotor development and dysgraphia in 16 young children. Found that control of spatial accuracy, not allograph retrieval or size control, discriminated dysgraphic children from others. Poor writers were less accurate than proficient…

  4. Calcium-induced calcium release supports recruitment of synaptic vesicles in auditory hair cells.

    Science.gov (United States)

    Castellano-Muñoz, Manuel; Schnee, Michael E; Ricci, Anthony J

    2016-01-01

    Hair cells from auditory and vestibular systems transmit continuous sound and balance information to the central nervous system through the release of synaptic vesicles at ribbon synapses. The high activity experienced by hair cells requires a unique mechanism to sustain recruitment and replenishment of synaptic vesicles for continuous release. Using pre- and postsynaptic electrophysiological recordings, we explored the potential contribution of calcium-induced calcium release (CICR) in modulating the recruitment of vesicles to auditory hair cell ribbon synapses. Pharmacological manipulation of CICR with agents targeting endoplasmic reticulum calcium stores reduced both spontaneous postsynaptic multiunit activity and the frequency of excitatory postsynaptic currents (EPSCs). Pharmacological treatments had no effect on hair cell resting potential or activation curves for calcium and potassium channels. However, these drugs exerted a reduction in vesicle release measured by dual-sine capacitance methods. In addition, calcium substitution by barium reduced release efficacy by delaying release onset and diminishing vesicle recruitment. Together these results demonstrate a role for calcium stores in hair cell ribbon synaptic transmission and suggest a novel contribution of CICR in hair cell vesicle recruitment. We hypothesize that calcium entry via calcium channels is tightly regulated to control timing of vesicle fusion at the synapse, whereas CICR is used to maintain a tonic calcium signal to modulate vesicle trafficking. Copyright © 2016 the American Physiological Society.

  5. Normal and Malignant Cells Exhibit Differential Responses to Calcium Electroporation.

    Science.gov (United States)

    Frandsen, Stine K; Krüger, Mie B; Mangalanathan, Uma M; Tramm, Trine; Mahmood, Faisal; Novak, Ivana; Gehl, Julie

    2017-08-15

    Calcium electroporation may offer a simple general tool for anticancer therapy. Transient permeabilization of cancer cell membranes created by applying short, high-voltage pulses in tumors enables high calcium influxes that trigger cell death. In this study, we compared the relative sensitivity of different human tumor models and normal tissues to calcium electroporation. Plasma membrane Ca(2+)-ATPase (PMCA) protein expression was confirmed in vitro in all cancer cell lines and normal primary dermal fibroblasts studied. In all tumor types tested in vivo, calcium electroporation effectively induced necrosis, with a range of sensitivities observed (36%-88%) 2 days after treatment. Necrosis was induced using calcium concentrations of 100-500 mmol/L and injection volumes 20%-80% of tumor volume. Notably, only limited effects were seen in normal tissue. Calcium content increased >7-fold in tumor and skin tissue after calcium electroporation but decreased in skin tissue 4 hours after treatment to levels comparable with untreated controls, whereas calcium content endured at high levels in tumor tissue. Mechanistic experiments in vitro indicated that calcium influx was similar in fibroblasts and cancer cells. However, we observed decreased PMCA expression in cancer cells compared with fibroblasts, offering a potential explanation for the different calcium content in tumor cells versus normal tissues. Overall, our results suggest that calcium electroporation can elicit a rapid and selective necrosis of solid tumors, with limited deleterious effects on surrounding normal tissues. Cancer Res; 77(16); 4389-401. ©2017 AACR. ©2017 American Association for Cancer Research.

  6. Minimal model for calcium alternans due to SR release refractoriness

    Science.gov (United States)

    Cantalapiedra, Inma R.; Alvarez-Lacalle, Enrique; Peñaranda, Angelina; Echebarria, Blas

    2017-09-01

    In the heart, rapid pacing rates may induce alternations in the strength of cardiac contraction, termed pulsus alternans. Often, this is due to an instability in the dynamics of the intracellular calcium concentration, whose transients become larger and smaller at consecutive beats. This alternation has been linked experimentally and theoretically to two different mechanisms: an instability due to (1) a strong dependence of calcium release on sarcoplasmic reticulum (SR) load, together with a slow calcium reuptake into the SR or (2) to SR release refractoriness, due to a slow recovery of the ryanodine receptors (RyR2) from inactivation. The relationship between calcium alternans and refractoriness of the RyR2 has been more elusive than the corresponding SR Ca load mechanism. To study the former, we reduce a general calcium model, which mimics the deterministic evolution of a calcium release unit, to its most basic elements. We show that calcium alternans can be understood using a simple nonlinear equation for calcium concentration at the dyadic space, coupled to a relaxation equation for the number of recovered RyR2s. Depending on the number of RyR2s that are recovered at the beginning of a stimulation, the increase in calcium concentration may pass, or not, over an excitability threshold that limits the occurrence of a large calcium transient. When the recovery of the RyR2 is slow, this produces naturally a period doubling bifurcation, resulting in calcium alternans. We then study the effects of inactivation, calcium diffusion, and release conductance for the onset of alternans. We find that the development of alternans requires a well-defined value of diffusion while it is less sensitive to the values of inactivation or release conductance.

  7. [Transient epileptic amnesia].

    Science.gov (United States)

    Muramatsu, Kazuhiro; Yoshizaki, Takahito

    2016-03-01

    Transient amnesia is one of common clinical phenomenon of epilepsy that are encountered by physicians. The amnestic attacks are often associated with persistent memory disturbances. Epilepsy is common among the elderly, with amnesia as a common symptom and convulsions relatively uncommon. Therefore, amnesia due to epilepsy can easily be misdiagnosed as dementia. The term 'transient epileptic amnesia (TEA)' was introduced in the early 1990s by Kapur, who highlighted that amnestic attacks caused by epilepsy can be similar to those occurring in 'transient global amnesia', but are distinguished by features brevity and recurrence. In 1998, Zeman et al. proposed diagnostic criteria for TEA.

  8. Characterization of a calcium/calmodulin-regulated SR/CAMTA gene family during tomato fruit development and ripening

    Directory of Open Access Journals (Sweden)

    Yang Tianbao

    2012-02-01

    Full Text Available Abstract Background Fruit ripening is a complicated development process affected by a variety of external and internal cues. It is well established that calcium treatment delays fruit ripening and senescence. However, the underlying molecular mechanisms remain unclear. Results Previous studies have shown that calcium/calmodulin-regulated SR/CAMTAs are important for modulation of disease resistance, cold sensitivity and wounding response in vegetative tissues. To study the possible roles of this gene family in fruit development and ripening, we cloned seven SR/CAMTAs, designated as SlSRs, from tomato, a model fruit-bearing crop. All seven genes encode polypeptides with a conserved DNA-binding domain and a calmodulin-binding site. Calmodulin specifically binds to the putative targeting site in a calcium-dependent manner. All SlSRs were highly yet differentially expressed during fruit development and ripening. Most notably, the expression of SlSR2 was scarcely detected at the mature green and breaker stages, two critical stages of fruit development and ripening; and SlSR3L and SlSR4 were expressed exclusively in fruit tissues. During the developmental span from 10 to 50 days post anthesis, the expression profiles of all seven SlSRs were dramatically altered in ripening mutant rin compared with wildtype fruit. By contrast, only minor alterations were noted for ripening mutant nor and Nr fruit. In addition, ethylene treatment of mature green wildtype fruit transiently stimulated expression of all SlSRs within one to two hours. Conclusions This study indicates that SlSR expression is influenced by both the Rin-mediated developmental network and ethylene signaling. The results suggest that calcium signaling is involved in the regulation of fruit development and ripening through calcium/calmodulin/SlSR interactions.

  9. Transient Ischemic Attack

    Medline Plus

    Full Text Available ... TIA , or transient ischemic attack, is a "mini stroke" that occurs when a blood clot blocks an ... a short time. The only difference between a stroke and TIA is that with TIA the blockage ...

  10. Transient tic disorder

    Science.gov (United States)

    ... makes 1 or many brief, repeated, movements or noises (tics). These movements or noises are involuntary (not on purpose). Causes Transient tic ... less than a year. Other disorders such as anxiety , attention deficit hyperactivity disorder ( ADHD ), uncontrollable movement ( myoclonus ), ...

  11. Transient Ischemic Attack

    Medline Plus

    Full Text Available ... Ischemic Attack TIA , or transient ischemic attack, is a "mini stroke" that occurs when a blood clot blocks an artery for a short time. The only difference between a stroke ...

  12. Transient Microcavity Sensor

    CERN Document Server

    Shu, Fang-Jie; Özdemir, Şahin Kaya; Yang, Lan; Guo, Guang-Can

    2015-01-01

    A transient and high sensitivity sensor based on high-Q microcavity is proposed and studied theoretically. There are two ways to realize the transient sensor: monitor the spectrum by fast scanning of probe laser frequency or monitor the transmitted light with fixed laser frequency. For both methods, the non-equilibrium response not only tells the ultrafast environment variance, but also enable higher sensitivity. As examples of application, the transient sensor for nanoparticles adhering and passing by the microcavity is studied. It's demonstrated that the transient sensor can sense coupling region, external linear variation together with the speed and the size of a nanoparticle. We believe that our researches will open a door to the fast dynamic sensing by microcavity.

  13. Transient multivariable sensor evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Vilim, Richard B.; Heifetz, Alexander

    2017-02-21

    A method and system for performing transient multivariable sensor evaluation. The method and system includes a computer system for identifying a model form, providing training measurement data, generating a basis vector, monitoring system data from sensor, loading the system data in a non-transient memory, performing an estimation to provide desired data and comparing the system data to the desired data and outputting an alarm for a defective sensor.

  14. Substitutions in Calcium Aluminates and Calcium Aluminoferrites.

    Science.gov (United States)

    ALUMINUM COMPOUNDS, *CEMENTS, * CALCIUM COMPOUNDS, * FERRITES , *SCIENTIFIC RESEARCH, INFRARED SPECTROSCOPY, X RAY DIFFRACTION, CHEMICAL COMPOSITION, SUBSTITUTES, CHEMICAL ANALYSIS, ALKALI METAL COMPOUNDS.

  15. Transient Pseudohypoparathyroidism as a Cause of Late-onset Hypocalcemia in Neonates and Infants

    Directory of Open Access Journals (Sweden)

    Cheng-Ting Lee

    2008-10-01

    Conclusion: Neuromuscular irritability is usually the initial clinical presentation of transient pseudohypoparathyroidism. Aside from delayed renal maturation, pseudohypoparathyroidism is also caused by magnesium deficiency. Such a disturbance usually resolves before 3 months of age.

  16. Diuretics for transient tachypnoea of the newborn.

    Science.gov (United States)

    Kassab, Manal; Khriesat, Wadah M; Anabrees, Jasim

    2015-11-21

    Transient tachypnoea of the newborn (TTN) results from delayed clearance of lung liquid and is a common cause of admission of full-term infants to neonatal intensive care units. The condition is particularly common after elective caesarean section. Conventional treatment involves appropriate oxygen administration and continuous positive airway pressure in some cases. Most infants receive antibiotic therapy. Hastening the clearance of lung liquid may shorten the duration of the symptoms and reduce complications. To determine whether diuretic administration reduces the duration of oxygen therapy and respiratory symptoms and shortens hospital stay in term infants presenting with transient tachypnoea of the newborn. An updated search was carried out in September 2015 of the following databases: the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library issue 9, 2015), MEDLINE via Ovid, EMBASE, PubMed, and CINAHL via OVID. We included randomised and quasi-randomised controlled trials that compared the effect of diuretics administration versus placebo or no treatment in infants of less than seven days of age, born at 37 or more weeks of gestation with the clinical picture of transient tachypnoea of the newborn. We extracted and analysed data according to the methods outlined in the latest Cochrane Handbook for Systematic Reviews of Interventions. Two review authors assessed trial quality in each potentially eligible manuscript and two review authors extracted data. Our previous systematic review included two trials enrolling a total of 100 infants with transient tachypnoea of the newborn (Wiswell 1985; Karabayir 2006). The updated search revealed no new trials. Wiswell 1985 randomised 50 infants to receive either oral furosemide (2 mg/kg body weight at time of diagnosis followed by a 1 mg/kg dose 12 hours later if the tachypnoea persisted) or placebo. Karabayir 2006 randomised 50 infants to receive either intravenous furosemide (2 mg/kg body

  17. Separation of intramembrane charging components in low-calcium solutions in frog skeletal muscle.

    Science.gov (United States)

    Huang, C L

    1991-08-01

    The inactivation of charge movement components by small (-100 to -70 mV) shifts in holding potential was examined in voltage-clamped intact amphibian muscle fibers in low [Ca2+], Mg(2+)-containing solutions. The pulse protocols used both large voltage excursions and smaller potential steps that elicited prolonged (q gamma) transients. Charge species were distinguished through the pharmacological effects of tetracaine. These procedures confirmed earlier observations in cut fibers and identified the following new properties of the q gamma charge. First, q gamma, previously defined as the tetracaine-sensitive charge, is also the component primarily responsible for the voltage-dependent inactivation induced by conditions of low extracellular [Ca2+]. Second, this inactivation separates a transient that includes a "hump" component and which has kinetics and a voltage dependence distinct from the monotonic decay that remains. Third, q gamma, previously associated with delayed charge movements, can also contribute significant charge transfer at early times. These findings suggest that the parallel inhibition of calcium signals and charge movements reported in low [Ca2+] solutions arises from influences on q gamma charge (Brum et al., 1988a, b). They also reconcile reports that implicate tetracaine-sensitive (q gamma) charge in excitation-contraction coupling with evidence that early intramembrane events are also involved in this process (Pizarro et al., 1989). Finally, they are relevant to hypotheses of possible feedback or feed-forward roles of q gamma in excitation-contraction coupling.

  18. Calcium channel blocker overdose

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/002580.htm Calcium-channel blocker overdose To use the sharing features on this page, please enable JavaScript. Calcium-channel blockers are a type of medicine used to ...

  19. Fenoprofen calcium overdose

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/002649.htm Fenoprofen calcium overdose To use the sharing features on this page, please enable JavaScript. Fenoprofen calcium is a type of medicine called a nonsteroidal ...

  20. Short-range intercellular calcium signaling in bone

    DEFF Research Database (Denmark)

    Jørgensen, Niklas Rye

    2005-01-01

    into biological effects in bone. Intercellular calcium waves are increases in intracellular calcium concentration in single cells, subsequently propagating to adjacent cells, and can be a possible mechanism for the coupling of bone formation to bone resorption. The aim of the present studies was to investigate...... whether bone cells are capable of communicating via intercellular calcium signals, and determine by which mechanisms the cells propagate the signals. First, we found that osteoblastic cells can propagate intercellular calcium transients upon mechanical stimulation, and that there are two principally...... different mechanisms for this propagation. One mechanism involves the secretion of a nucleotide, possibly ATP, acting in an autocrine action to purinergic P2Y2 receptors on the neighboring cells, leading to intracellular IP3 generation and subsequent release of calcium from intracellular stores. The other...

  1. Calcium and Mitosis

    Science.gov (United States)

    Hepler, P.

    1983-01-01

    Although the mechanism of calcium regulation is not understood, there is evidence that calcium plays a role in mitosis. Experiments conducted show that: (1) the spindle apparatus contains a highly developed membrane system that has many characteristics of sarcoplasmic reticulum of muscle; (2) this membrane system contains calcium; and (3) there are ionic fluxes occurring during mitosis which can be seen by a variety of fluorescence probes. Whether the process of mitosis can be modulated by experimentally modulating calcium is discussed.

  2. Time course of activation of calcium release from sarcoplasmic reticulum in skeletal muscle.

    OpenAIRE

    Simon, B J; Schneider, M F

    1988-01-01

    Myoplasmic free calcium transients were measured with antipyrylazo III in voltage clamped segments of frog skeletal muscle fibers and were used to calculate the rate of release (Rrel) of calcium from the sarcoplasmic reticulum. Intramembrane charge movement was measured for the same pulses in the same fibers. During a depolarizing pulse Rrel rose to an early peak and then decayed relatively rapidly but incompletely due to calcium-dependent inactivation (Schneider M.F., and B.J. Simon. 1988. J...

  3. Calcium en cardioplegie

    NARCIS (Netherlands)

    Ruigrok, T.J.C.; Meijler, F.L.

    1985-01-01

    Coronary perfusion with a calcium-free solution, followed by reperfusion with a calcium containing solution, may result in acute myocardial cell death and in irreversible loss of the e1ectrical and mechanical activity of the heart. This phenomenon is known as the calcium paradox. A number of

  4. Delayed Orgasm and Anorgasmia

    OpenAIRE

    JENKINS, Lawrence C.; Mulhall, John P.

    2015-01-01

    Delayed orgasm/anorgasmia defined as the persistent or recurrent difficulty, delay in, or absence of attaining orgasm after sufficient sexual stimulation, which causes personal distress. Delayed orgasm and anorgasmia are associated with significant sexual dissatisfaction. A focused medical history can shed light on the potential etiologies; which include: medications, penile sensation loss, endocrinopathies, penile hyperstimulation and psychological etiologies, amongst others. Unfortunately, ...

  5. Calcium antagonists and the diabetic hypertensive patient

    DEFF Research Database (Denmark)

    Parving, H H; Rossing, P

    1993-01-01

    reduces albuminuria, delays the progression of nephropathy, and postpones renal insufficiency in diabetic nephropathy. Calcium antagonists and angiotensin converting enzyme inhibitors induce an acute increase in the glomerular filtration rate, renal plasma flow, and renal sodium excretion...... nephropathy alone and is rapidly rising. Increased arterial blood pressure is an early and common finding in incipient and overt diabetic nephropathy. Fluid and sodium retention with normal concentrations of active renin, angiotensin I and II, and aldosterone has been demonstrated in diabetic renal disease...

  6. Interfering with calcium release suppresses I gamma, the "hump" component of intramembranous charge movement in skeletal muscle.

    Science.gov (United States)

    Csernoch, L; Pizarro, G; Uribe, I; Rodríguez, M; Ríos, E

    1991-05-01

    Four manifestations of excitation-contraction (E-C) coupling were derived from measurements in cut skeletal muscle fibers of the frog, voltage clamped in a Vaseline-gap chamber: intramembranous charge movement currents, myoplasmic [Ca2+] transients, flux of calcium release from the sarcoplasmic reticulum (SR), and the intrinsic optical transparency change that accompanies calcium release. In attempts to suppress Ca release by direct effects on the SR, three interventions were applied: (a) a conditioning pulse that causes calcium release and inhibits release in subsequent pulses by Ca-dependent inactivation; (b) a series of brief, large pulses, separated by long intervals (greater than 700 ms), which deplete Ca2+ in the SR; and (c) intracellular application of the release channel blocker ruthenium red. All these reduced calcium release flux. None was expected to affect directly the voltage sensor of the T-tubule; however, all of them reduced or eliminated a component of charge movement current with the following characteristics: (a) delayed onset, peaking 10-20 ms into the pulse; (b) current reversal during the pulse, with an inward phase after the outward peak; and (c) OFF transient of smaller magnitude than the ON, of variable polarity, and sometimes biphasic. When the total charge movement current had a visible hump, the positive phase of the current eliminated by the interventions agreed with the hump in timing and size. The component of charge movement current blocked by the interventions was greater and had a greater inward phase in slack fibers with high [EGTA] inside than in stretched fibers with no EGTA. Its amplitude at -40 mV was on average 0.26 A/F (SEM 0.03) in slack fibers. The waveform of release flux determined from the Ca transients measured simultaneously with the membrane currents had, as described previously (Melzer, W., E. Ríos, and M. F. Schneider. 1984. Biophysical Journal. 45:637-641), an early peak followed by a descent to a steady level

  7. The Yin and Yang of Calcium Effects on Synaptic Vesicle Endocytosis

    Science.gov (United States)

    Wu, Xin-Sheng

    2014-01-01

    A large number of studies suggest that calcium triggers and accelerates vesicle endocytosis at many synapses and non-neuronal secretory cells. However, many studies show that prolonging the duration of the stimulation train, which induces more calcium influx, slows down endocytosis; and several studies suggest that instead of triggering endocytosis, calcium actually inhibits endocytosis. Here we addressed this apparent conflict at a large nerve terminal, the calyx of Held in rat brainstem, in which recent studies suggest that transient calcium increase up to tens of micromolar concentration at the micro/nano domain triggers endocytosis. By dialyzing 0–1 μm calcium into the calyx via a whole-cell pipette, we found that slow endocytosis was inhibited by calcium dialysis in a concentration-dependent manner. Thus, prolonged, small, and global calcium increase inhibits endocytosis, whereas transient and large calcium increase at the micro/nano domain triggers endocytosis and facilitates endocytosis. This yin and yang effect of calcium may reconcile apparent conflicts regarding whether calcium accelerates or inhibits endocytosis. Whether endocytosis is fast or slow depends on the net outcome between the yin and yang effect of calcium. PMID:24523554

  8. Transient Heat Conduction

    DEFF Research Database (Denmark)

    Rode, Carsten

    1998-01-01

    Analytical theory of transient heat conduction.Fourier's law. General heat conducation equation. Thermal diffusivity. Biot and Fourier numbers. Lumped analysis and time constant. Semi-infinite body: fixed surface temperature, convective heat transfer at the surface, or constant surface heat flux...

  9. Transient cavitation in pipelines

    NARCIS (Netherlands)

    Kranenburg, C.

    1974-01-01

    The aim of the present study is to set up a one-dimensional mathematical model, which describes the transient flow in pipelines, taking into account the influence of cavitation and free gas. The flow will be conceived of as a three-phase flow of the liquid, its vapour and non-condensible gas. The

  10. High speed two-photon imaging of calcium dynamics in dendritic spines: consequences for spine calcium kinetics and buffer capacity.

    Directory of Open Access Journals (Sweden)

    L Niels Cornelisse

    Full Text Available Rapid calcium concentration changes in postsynaptic structures are crucial for synaptic plasticity. Thus far, the determinants of postsynaptic calcium dynamics have been studied predominantly based on the decay kinetics of calcium transients. Calcium rise times in spines in response to single action potentials (AP are almost never measured due to technical limitations, but they could be crucial for synaptic plasticity. With high-speed, precisely-targeted, two-photon point imaging we measured both calcium rise and decay kinetics in spines and secondary dendrites in neocortical pyramidal neurons. We found that both rise and decay kinetics of changes in calcium-indicator fluorescence are about twice as fast in spines. During AP trains, spine calcium changes follow each AP, but not in dendrites. Apart from the higher surface-to-volume ratio (SVR, we observed that neocortical dendritic spines have a markedly smaller endogenous buffer capacity with respect to their parental dendrites. Calcium influx time course and calcium extrusion rate were both in the same range for spines and dendrites when fitted with a dynamic multi-compartment model that included calcium binding kinetics and diffusion. In a subsequent analysis we used this model to investigate which parameters are critical determinants in spine calcium dynamics. The model confirmed the experimental findings: a higher SVR is not sufficient by itself to explain the faster rise time kinetics in spines, but only when paired with a lower buffer capacity in spines. Simulations at zero calcium-dye conditions show that calmodulin is more efficiently activated in spines, which indicates that spine morphology and buffering conditions in neocortical spines favor synaptic plasticity.

  11. High speed two-photon imaging of calcium dynamics in dendritic spines: consequences for spine calcium kinetics and buffer capacity.

    Science.gov (United States)

    Cornelisse, L Niels; van Elburg, Ronald A J; Meredith, Rhiannon M; Yuste, Rafael; Mansvelder, Huibert D

    2007-10-24

    Rapid calcium concentration changes in postsynaptic structures are crucial for synaptic plasticity. Thus far, the determinants of postsynaptic calcium dynamics have been studied predominantly based on the decay kinetics of calcium transients. Calcium rise times in spines in response to single action potentials (AP) are almost never measured due to technical limitations, but they could be crucial for synaptic plasticity. With high-speed, precisely-targeted, two-photon point imaging we measured both calcium rise and decay kinetics in spines and secondary dendrites in neocortical pyramidal neurons. We found that both rise and decay kinetics of changes in calcium-indicator fluorescence are about twice as fast in spines. During AP trains, spine calcium changes follow each AP, but not in dendrites. Apart from the higher surface-to-volume ratio (SVR), we observed that neocortical dendritic spines have a markedly smaller endogenous buffer capacity with respect to their parental dendrites. Calcium influx time course and calcium extrusion rate were both in the same range for spines and dendrites when fitted with a dynamic multi-compartment model that included calcium binding kinetics and diffusion. In a subsequent analysis we used this model to investigate which parameters are critical determinants in spine calcium dynamics. The model confirmed the experimental findings: a higher SVR is not sufficient by itself to explain the faster rise time kinetics in spines, but only when paired with a lower buffer capacity in spines. Simulations at zero calcium-dye conditions show that calmodulin is more efficiently activated in spines, which indicates that spine morphology and buffering conditions in neocortical spines favor synaptic plasticity.

  12. Calcium transient and sodium-calcium exchange current in human versus rabbit sinoatrial node pacemaker cells

    NARCIS (Netherlands)

    Verkerk, Arie O.; van Borren, Marcel M. G. J.; Wilders, Ronald

    2013-01-01

    There is an ongoing debate on the mechanism underlying the pacemaker activity of sinoatrial node (SAN) cells, focusing on the relative importance of the "membrane clock" and the "Ca(2+) clock" in the generation of the small net membrane current that depolarizes the cell towards the action potential

  13. Transient FDTD simulation validation

    OpenAIRE

    Jauregui Tellería, Ricardo; Riu Costa, Pere Joan; Silva Martínez, Fernando

    2010-01-01

    In computational electromagnetic simulations, most validation methods have been developed until now to be used in the frequency domain. However, the EMC analysis of the systems in the frequency domain many times is not enough to evaluate the immunity of current communication devices. Based on several studies, in this paper we propose an alternative method of validation of the transients in time domain allowing a rapid and objective quantification of the simulations results.

  14. Transient cerebral ischemia.

    OpenAIRE

    Cusimano, M D; Ameli, F M

    1989-01-01

    Stroke is a major cause of disability and death in North America. About 30% to 40% of patients with stroke have had transient ischemic attacks (TIAs). The recognition and treatment of TIAs and possibly of asymptomatic stenoses of the carotid arteries may be beneficial in preventing stroke. We review the epidemiologic features, natural history, pathogenetic features, clinical presentation, methods of investigation and management of patients with TIAs.

  15. Early and late components of EEG delay activity correlate differently with scene working memory performance.

    Science.gov (United States)

    Ellmore, Timothy M; Ng, Kenneth; Reichert, Chelsea P

    2017-01-01

    Sustained and elevated activity during the working memory delay period has long been considered the primary neural correlate for maintaining information over short time intervals. This idea has recently been reinterpreted in light of findings generated from multiple neural recording modalities and levels of analysis. To further investigate the sustained or transient nature of activity, the temporal-spectral evolution (TSE) of delay period activity was examined in humans with high density EEG during performance of a Sternberg working memory paradigm with a relatively long six second delay and with novel scenes as stimuli. Multiple analyses were conducted using different trial window durations and different baseline periods for TSE computation. Sensor level analyses revealed transient rather than sustained activity during delay periods. Specifically, the consistent finding among the analyses was that high amplitude activity encompassing the theta range was found early in the first three seconds of the delay period. These increases in activity early in the delay period correlated positively with subsequent ability to distinguish new from old probe scenes. Source level signal estimation implicated a right parietal region of transient early delay activity that correlated positively with working memory ability. This pattern of results adds to recent evidence that transient rather than sustained delay period activity supports visual working memory performance. The findings are discussed in relation to synchronous and desynchronous intra- and inter-regional neural transmission, and choosing an optimal baseline for expressing temporal-spectral delay activity change.

  16. Transient osteoporosis of the hip: A mysterious cause of hip pain in adults

    Directory of Open Access Journals (Sweden)

    Raju Vaishya

    2017-01-01

    Full Text Available Background: Transient osteoporosis of the hip (TOH is a poorly understood and forgotten clinical entity. The diagnosis is often delayed, and inappropriate treatment is provided, due to the lack of its awareness among the clinicians. Materials and Methods: Twelve patients (11 male and one female within the age group of 35–50 years, were identified retrospectively from the hospital records between July 2011 and June 2015 who had evidence of TOH on clinical and radiological parameters. Results: All the patients were treated conservatively by nonweight bearing mobilization, anti-inflammatory drugs, bisphosphonates, calcium, and Vitamin D supplements. None of our patients had any symptoms after 6 months of conservative management. The disease did not progress, and there was no evidence of hip joint involvement in any of the cases. Plain radiographs were not diagnostic in the early detection of TOH. Magnetic resonance imaging was found to be highly specific and sensitive in diagnosing TOH. The clinical condition of TOH is characterized by its acute onset of hip pain in middle-aged people, and its symptoms are out of proportion to the radiological findings. Conclusion: The TOH is a nondestructive and self-limiting condition of the hip, which responds well to the conservative treatment. We believe that TOH could be a subset of complex regional pain syndrome type 1, as it has many similarities in clinical presentation and management. Awareness of this entity is important to the clinicians for an early diagnosis and to avoid unnecessary treatment for other mimicking conditions.

  17. Transient Astrophysics Probe

    Science.gov (United States)

    Camp, Jordan

    2017-08-01

    Transient Astrophysics Probe (TAP), selected by NASA for a funded Concept Study, is a wide-field high-energy transient mission proposed for flight starting in the late 2020s. TAP’s main science goals, called out as Frontier Discovery areas in the 2010 Decadal Survey, are time-domain astrophysics and counterparts of gravitational wave (GW) detections. The mission instruments include unique imaging soft X-ray optics that allow ~500 deg2 FoV in each of four separate modules; a high sensitivity, 1 deg2 FoV soft X-ray telescope based on single crystal silicon optics; a passively cooled, 1 deg2 FoV Infrared telescope with bandpass 0.6-3 micron; and a set of ~8 small NaI gamma-ray detectors. TAP will observe many events per year of X-ray transients related to compact objects, including tidal disruptions of stars, supernova shock breakouts, neutron star bursts and superbursts, and high redshift Gamma-Ray Bursts. Perhaps most exciting is TAP’s capability to observe X-ray and IR counterparts of GWs involving stellar mass black holes detected by LIGO/Virgo, and possibly X-ray counterparts of GWs from supermassive black holes, detected by LISA and Pulsar Timing Arrays.

  18. Advanced PFBC transient analysis

    Energy Technology Data Exchange (ETDEWEB)

    White, J.S. [Parsons Power Group, Inc., Reading, PA (United States); Bonk, D.L.; Rogers, L. [USDOE Morgantown Energy Technology Center, WV (United States)

    1996-12-31

    Transient modeling and analysis of Advanced Pressurized Fluidized Bed Combustion (PFBC) systems is a research area that is currently under investigative study by the United States Department of Energy`s Morgantown Energy Technology Center (METC). The object of the effort is to identify key operating parameters affecting plant performance and then quantify the basic response of major sub-systems to changes in operating conditions. PC-TRAX, a commercially available dynamic software program, was chosen and applied in this modeling and analysis effort. This paper summarizes and describes the development of a series of TRAX-based transient models of Advanced PFBC power plants. These power plants generate a high temperature flue gas by burning coal or other suitable fuel in a PFBC. The high temperature flue gas supports low-Btu fuel gas or natural gas combustion in a gas turbine topping combustor. When utilized, low-Btu fuel gas is produced in a bubbling bed carbonizer. High temperature, high pressure combustion products exiting the topping combustor are expanded in a modified gas turbine to generate electrical power. Waste heat from the system is used to generate and superheat steam for a reheat steam turbine bottoming cycle that generates additional electrical power. Basic control/instrumentation models were developed and modeled in PC-TRAX and used to investigate off-design plant performance. System performance for various transient conditions and control philosophies was studied.

  19. Advanced PFBC transient analysis

    Energy Technology Data Exchange (ETDEWEB)

    White, J.S. [Parsons Power Group, Inc., Reading, PA (United States); Bonk, D.L. [USDOE Federal Energy Technology Center, Morgantown, WV (United States)

    1997-05-01

    Transient modeling and analysis of advanced Pressurized Fluidized Bed Combustion (PFBC) systems is a research area that is currently under investigation by the US Department of Energy`s Federal Energy Technology Center (FETC). The object of the effort is to identify key operating parameters that affect plant performance and then quantify the basic response of major sub-systems to changes in operating conditions. PC-TRAX{trademark}, a commercially available dynamic software program, was chosen and applied in this modeling and analysis effort. This paper describes the development of a series of TRAX-based transient models of advanced PFBC power plants. These power plants burn coal or other suitable fuel in a PFBC, and the high temperature flue gas supports low-Btu fuel gas or natural gas combustion in a gas turbine topping combustor. When it is utilized, the low-Btu fuel gas is produced in a bubbling bed carbonizer. High temperature, high pressure combustion products exiting the topping combustor are expanded in a modified gas turbine to generate electrical power. Waste heat from the system is used to raise and superheat steam for a reheat steam turbine bottoming cycle that generates additional electrical power. Basic control/instrumentation models were developed and modeled in PC-TRAX and used to investigate off-design plant performance. System performance for various transient conditions and control philosophies was studied.

  20. Calcium channel blocker poisoning

    Directory of Open Access Journals (Sweden)

    Miran Brvar

    2005-04-01

    Full Text Available Background: Calcium channel blockers act at L-type calcium channels in cardiac and vascular smooth muscles by preventing calcium influx into cells with resultant decrease in vascular tone and cardiac inotropy, chronotropy and dromotropy. Poisoning with calcium channel blockers results in reduced cardiac output, bradycardia, atrioventricular block, hypotension and shock. The findings of hypotension and bradycardia should suggest poisoning with calcium channel blockers.Conclusions: Treatment includes immediate gastric lavage and whole-bowel irrigation in case of ingestion of sustainedrelease products. All patients should receive an activated charcoal orally. Specific treatment includes calcium, glucagone and insulin, which proved especially useful in shocked patients. Supportive care including the use of catecholamines is not always effective. In the setting of failure of pharmacological therapy transvenous pacing, balloon pump and cardiopulmonary by-pass may be necessary.

  1. Delays in thick targets

    CERN Document Server

    Bennett, J R J

    2002-01-01

    The delays in the emission of radioactive particles from a thick target bombarded by high-energy protons is discussed in relation to the basic physical processes of diffusion and effusion through the target and ioniser. The delay time, relative to the decay time, is crucial to the efficiency of particle release at the exit of the ioniser. The principles of minimizing the delay times are discussed with reference to a mathematical model of the process, and some experimental examples are given.

  2. Interaction of H2S with Calcium Permeable Channels and Transporters

    Directory of Open Access Journals (Sweden)

    Weihua Zhang

    2015-01-01

    Full Text Available A growing amount of evidence has suggested that hydrogen sulfide (H2S, as a gasotransmitter, is involved in intensive physiological and pathological processes. More and more research groups have found that H2S mediates diverse cellular biological functions related to regulating intracellular calcium concentration. These groups have demonstrated the reciprocal interaction between H2S and calcium ion channels and transporters, such as L-type calcium channels (LTCC, T-type calcium channels (TTCC, sodium/calcium exchangers (NCX, transient receptor potential (TRP channels, β-adrenergic receptors, and N-methyl-D-aspartate receptors (NMDAR in different cells. However, the understanding of the molecular targets and mechanisms is incomplete. Recently, some research groups demonstrated that H2S modulates the activity of calcium ion channels through protein S-sulfhydration and polysulfide reactions. In this review, we elucidate that H2S controls intracellular calcium homeostasis and the underlying mechanisms.

  3. Delayed orgasm and anorgasmia.

    Science.gov (United States)

    Jenkins, Lawrence C; Mulhall, John P

    2015-11-01

    Delayed orgasm/anorgasmia defined as the persistent or recurrent difficulty, delay in, or absence of attaining orgasm after sufficient sexual stimulation, which causes personal distress. Delayed orgasm and anorgasmia are associated with significant sexual dissatisfaction. A focused medical history can shed light on the potential etiologies, which include medications, penile sensation loss, endocrinopathies, penile hyperstimulation, and psychological etiologies. Unfortunately, there are no excellent pharmacotherapies for delayed orgasm/anorgasmia, and treatment revolves largely around addressing potential causative factors and psychotherapy. Copyright © 2015 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

  4. The effects of calcium on the expression of genes involved in ...

    African Journals Online (AJOL)

    USER

    2010-06-14

    Jun 14, 2010 ... etiolated tomato seedlings (Zhang et al., 2002), delays fruit ripening (Ferguson, 1984), flower senescence and flower abscission (Glenn et al., 1988). Calcium, in the form of calcium pectate, binds adjacent cells and acts as a type of cementing agent within cell walls. Cementing is presumed to occur when ...

  5. Transient Reliability of Ceramic Structures For Heat Engine Applications

    Science.gov (United States)

    Nemeth, Noel N.; Jadaan, Osama M.

    2002-01-01

    The objectives of this report was to develop a methodology to predict the time-dependent reliability (probability of failure) of brittle material components subjected to transient thermomechanical loading, taking into account the change in material response with time. This methodology for computing the transient reliability in ceramic components subjected to fluctuation thermomechanical loading was developed, assuming SCG (Slow Crack Growth) as the delayed mode of failure. It takes into account the effect of varying Weibull modulus and materials with time. It was also coded into a beta version of NASA's CARES/Life code, and an example demonstrating its viability was presented.

  6. Decoding calcium signaling across the nucleus.

    Science.gov (United States)

    Oliveira, André G; Guimarães, Erika S; Andrade, Lídia M; Menezes, Gustavo B; Fatima Leite, M

    2014-09-01

    Calcium (Ca(2+)) is an important multifaceted second messenger that regulates a wide range of cellular events. A Ca(2+)-signaling toolkit has been shown to exist in the nucleus and to be capable of generating and modulating nucleoplasmic Ca(2+) transients. Within the nucleus, Ca(2+) controls cellular events that are different from those modulated by cytosolic Ca(2+). This review focuses on nuclear Ca(2+) signals and their role in regulating physiological and pathological processes. ©2014 Int. Union Physiol. Sci./Am. Physiol. Soc.

  7. American Dream Delayed

    DEFF Research Database (Denmark)

    Khorunzhina, Natalia; Miller, Robert A.

    This paper investigates the delay in homeownership and a subsequent reduction in homeownership rate observed over the past decades. We focus on the delay in giving birth to children and increased labor market participation as contributing factors to homeownership dynamics for prime-age female hou...

  8. Familial Transient Global Amnesia

    Directory of Open Access Journals (Sweden)

    R.Rhys Davies

    2012-12-01

    Full Text Available Following an episode of typical transient global amnesia (TGA, a female patient reported similar clinical attacks in 2 maternal aunts. Prior reports of familial TGA are few, and no previous account of affected relatives more distant than siblings or parents was discovered in a literature survey. The aetiology of familial TGA is unknown. A pathophysiological mechanism akin to that in migraine attacks, comorbidity reported in a number of the examples of familial TGA, is one possibility. The study of familial TGA cases might facilitate the understanding of TGA aetiology.

  9. [Transient removable dentures].

    Science.gov (United States)

    Kouadio, A A; Jordana, F; N'Goran, J K; Le Bars, P

    2015-09-01

    Removable dentures are always transient current. The epidemiology and causes of tooth gaps demonstrate the need to master the different prosthetic treatment. This made whether to propose treatment plans that take into account psychological, physiological and technical support for this patient. Different situations may arise. A gradual transition may be considered or immediate passage to the total edentulous according to general criteria, local and desiderata of patients. After tooth extraction, the transitional prosthesis can control bone lysis thereby it is part of a complete treatment before prosthesis. It also facilitates a good psychological and physiological integration before the prosthesis use.

  10. Acidosis and Urinary Calcium Excretion

    DEFF Research Database (Denmark)

    Alexander, R Todd; Cordat, Emmanuelle; Chambrey, Régine

    2016-01-01

    Metabolic acidosis is associated with increased urinary calcium excretion and related sequelae, including nephrocalcinosis and nephrolithiasis. The increased urinary calcium excretion induced by metabolic acidosis predominantly results from increased mobilization of calcium out of bone and inhibi...

  11. Predicting aging caused delay degradation with alternative IDDT testing in a VLIW processor

    NARCIS (Netherlands)

    Kerkhoff, Hans G.; Zhao, Yong

    In this paper, delay and transient power-supply current (IDDT) testing has been applied for a 90nm VLIW DSP IP core, to demonstrate the IDDT testing an effective alternative of delay testing to detect aging degradation. The test environment for validation, implementing an accelerated test (AT) has

  12. Calcium and bones

    Science.gov (United States)

    ... eat in their diet. Vitamin D is the hormone that helps the gut absorb more calcium. Many older adults have common risks that make bone health worse. Calcium intake in the diet (milk, cheese, yogurt) is low. Vitamin D levels are ...

  13. Calcium D-saccharate

    DEFF Research Database (Denmark)

    Garcia, André Castilho; Hedegaard, Martina Vavrusova; Skibsted, Leif Horsfelt

    2016-01-01

    Molar conductivity of saturated aqueous solutions of calcium d-saccharate, used as a stabilizer of beverages fortified with calcium d-gluconate, increases strongly upon dilution, indicating complex formation between calcium and d-saccharate ions, for which, at 25 °C, Kassoc = 1032 ± 80, ΔHassoc......° = -34 ± 6 kJ mol-1, and ΔSassoc° = -55 ± 9 J mol-1 K-1, were determined electrochemically. Calcium d-saccharate is sparingly soluble, with a solubility product, Ksp, of (6.17 ± 0.32) × 10-7 at 25 °C, only moderately increasing with the temperature: ΔHsol° = 48 ± 2 kJ mol-1, and ΔSassoc° = 42 ± 7 J mol-1...... K-1. Equilibria in supersaturated solutions of calcium d-saccharate seem only to adjust slowly, as seen from calcium activity measurements in calcium d-saccharate solutions made supersaturated by cooling. Solutions formed by isothermal dissolution of calcium d-gluconate in aqueous potassium d...

  14. Extracellular Calcium and Magnesium

    African Journals Online (AJOL)

    ABSTRACT. The cause of preeclampsia remains unknown and calcium and magnesium supplement are being suggested as means of prevention. The objective of this study was to assess magnesium and calcium in the plasma and cerebrospinal fluid of Nigerian women with preedamp sia and eclampsia. Setting was ...

  15. Pre-harvest calcium sulfate application improves postharvest quality ...

    African Journals Online (AJOL)

    CaSO4 treatment promoted bud opening and delayed senescence. The treated flowers stayed turgid and continued their initial postharvest growth for longer periods of time. CaSO4 spray increased calcium (Ca) content of stems, leaves and petals of flowers and suppressed ethylene production and ion leakage with age.

  16. The predominant mechanism of intercellular calcium wave propagation changes during long-term culture of human osteoblast-like cells

    DEFF Research Database (Denmark)

    Henriksen, Zanne; Hiken, Jeffrey F; Steinberg, Thomas H

    2006-01-01

    Intercellular calcium waves (ICW) are calcium transients that spread from cell to cell in response to different stimuli. We previously demonstrated that human osteoblast-like cells in culture propagate ICW in response to mechanical stimulation by two mechanisms. One mechanism involves autocrine a...

  17. Transient dimers of allergens.

    Directory of Open Access Journals (Sweden)

    Juha Rouvinen

    Full Text Available BACKGROUND: Allergen-mediated cross-linking of IgE antibodies bound to the FcepsilonRI receptors on the mast cell surface is the key feature of the type I allergy. If an allergen is a homodimer, its allergenicity is enhanced because it would only need one type of antibody, instead of two, for cross-linking. METHODOLOGY/PRINCIPAL FINDINGS: An analysis of 55 crystal structures of allergens showed that 80% of them exist in symmetric dimers or oligomers in crystals. The majority are transient dimers that are formed at high protein concentrations that are reached in cells by colocalization. Native mass spectrometric analysis showed that native allergens do indeed form transient dimers in solution, while hypoallergenic variants of them exist almost solely in the monomeric form. We created a monomeric Bos d 5 allergen and show that it has a reduced capability to induce histamine release. CONCLUSIONS/SIGNIFICANCE: The results suggest that dimerization would be a very common and essential feature for allergens. Thus, the preparation of purely monomeric variants of allergens could open up novel possibilities for specific immunotherapy.

  18. Transient regional osteoporosis

    Directory of Open Access Journals (Sweden)

    F. Trotta

    2011-09-01

    Full Text Available Transient osteoporosis of the hip and regional migratory osteoporosis are uncommon and probably underdiagnosed bone diseases characterized by pain and functional limitation mainly affecting weight-bearing joints of the lower limbs. These conditions are usually self-limiting and symptoms tend to abate within a few months without sequelae. Routine laboratory investigations are unremarkable. Middle aged men and women during the last months of pregnancy or in the immediate post-partum period are principally affected. Osteopenia with preservation of articular space and transitory edema of the bone marrow provided by magnetic resonance imaging are common to these two conditions, so they are also known by the term regional transitory osteoporosis. The appearance of bone marrow edema is not specific to regional transitory osteoporosis but can be observed in several diseases, i.e. trauma, reflex sympathetic dystrophy, avascular osteonecrosis, infections, tumors from which it must be differentiated. The etiology of this condition is unknown. Pathogenesis is still debated in particular the relationship with reflex sympathetic dystrophy, with which regional transitory osteoporosis is often identified. The purpose of the present review is to remark on the relationship between transient osteoporosis of the hip and regional migratory osteoporosis with particular attention to the bone marrow edema pattern and relative differential diagnosis.

  19. Voltage-dependent mobilization of intracellular calcium in skeletal muscle.

    Science.gov (United States)

    Schneider, M F

    1986-01-01

    In skeletal muscle calcium is released from the sarcoplasmic reticulum (SR), an internal organelle, in response to changes in the voltage across the transverse tubule (T-tubule) membrane, an external membrane system that is distinct from the SR but in close proximity to it. For T-tubule voltage changes within the physiological range, calcium release can be turned on or off on a time scale of milliseconds. The control of calcium release from the SR appears to involve at least three functional components: a voltage sensor in the T-tubule membrane, a calcium channel in the SR, and a mechanism for coupling the voltage sensor to the channel. Movement of charged or dipolar molecules within the T-tubule membrane is thought to serve as the voltage sensor. Such intramembrane charge movement (Q) can be monitored electrically and can be compared with the rate of calcium release from the SR. Calcium release is calculated from cytosolic calcium transients measured with a metallochromic indicator. Comparison of Q and the rate of release in the same isolated muscle fibre indicates that this rate is directly proportional to the amount of charge displaced in excess of a 'threshold' amount. The nature of the coupling mechanism between T-tubules and SR remains to be established but present observations impose some restrictions on possible mechanisms.

  20. HYPERTHERMIA, INTRACELLULAR FREE CALCIUM AND CALCIUM IONOPHORES

    NARCIS (Netherlands)

    STEGE, GJJ; WIERENGA, PK; KAMPINGA, HH; KONINGS, AWT

    1993-01-01

    It is shown that heat-induced increase of intracellular calcium does not correlate with hyperthermic cell killing. Six different cell lines were investigated; in four (EAT, HeLa S3, L5178Y-R and L5178Y-S) heat treatments killing 90% of the cells did not affect the levels of intracellular free

  1. Calcium-induced voltage gating in single conical nanopores.

    Science.gov (United States)

    Siwy, Zuzanna S; Powell, Matthew R; Petrov, Alexander; Kalman, Eric; Trautmann, Christina; Eisenberg, Robert S

    2006-08-01

    We examine time signals of ion current through single conically shaped nanopores in the presence of sub-millimolar concentrations of calcium ions. We show that calcium induces voltage-dependent ion current fluctuations in time in addition to the previously reported negative incremental resistance (Nano Lett. 2006, 6, 473-477). These current fluctuations occur on the millisecond time scale at voltages at which the effect of negative incremental resistance was observed. We explain the fluctuations as results of transient binding of calcium ions to carboxyl groups on the pore walls that cause transient changes in electric potential inside a conical nanopore. We support this explanation by recordings of ion current in the presence of manganese ions that bind to carboxyl groups 3 orders of magnitude more tightly than calcium ions. The system of a single conical nanopore with calcium ions is compared to a semiconductor device of a unijunction transistor in electronic circuits. A unijunction transistor also exhibits negative incremental resistance and current instabilities.

  2. Reduced levels of intracellular calcium releasing in spermatozoa from asthenozoospermic patients

    Directory of Open Access Journals (Sweden)

    García Juan F

    2009-02-01

    Full Text Available Abstract Background Asthenozoospermia is one of the most common findings present in infertile males characterized by reduced or absent sperm motility, but its aetiology remains unknown in most cases. In addition, calcium is one of the most important ions regulating sperm motility. In this study we have investigated the progesterone-evoked intracellular calcium signal in ejaculated spermatozoa from men with normospermia or asthenozoospermia. Methods Human ejaculates were obtained from healthy volunteers and asthenospermic men by masturbation after 4–5 days of abstinence. For determination of cytosolic free calcium concentration, spermatozoa were loaded with the fluorescent ratiometric calcium indicator Fura-2. Results Treatment of spermatozoa from normospermic men with 20 micromolar progesterone plus 1 micromolar thapsigargin in a calcium free medium induced a typical transient increase in cytosolic free calcium concentration due to calcium release from internal stores. Similar results were obtained when spermatozoa were stimulated with progesterone alone. Subsequent addition of calcium to the external medium evoked a sustained elevation in cytosolic free calcium concentration indicative of capacitative calcium entry. However, when progesterone plus thapsigargin were administered to spermatozoa from patients with asthenozoospermia, calcium signal and subsequent calcium entry was much smaller compared to normospermic patients. As expected, pretreatment of normospermic spermatozoa with both the anti-progesterone receptor c262 antibody and with progesterone receptor antagonist RU-38486 decreased the calcium release induced by progesterone. Treatment of spermatozoa with cytochalasin D or jasplakinolide decreased the calcium entry evoked by depletion of internal calcium stores in normospermic patients, whereas these treatments proved to be ineffective at modifying the calcium entry in patients with asthenozoospermia. Conclusion Our results suggest

  3. Cocktails for Franssen: Asynchronous transient bias and other attentional factors in auditory localization

    Science.gov (United States)

    Whitmer, William M.; Brown, Christopher A.; Dye, Raymond H.; Jurcin, Noah F.

    2003-04-01

    The cocktail-party paradigm was applied to nonspeech signals. Pure-tone stimuli were used in an extension of the Franssen effect, an auditory illusion wherein the location of a slow-onset signal is perceived to be the same as a simultaneous, contralateral sudden-onset signal. Listeners heard simultaneous sudden-onset (transient) and contralateral slow-onset (steady-state) tones in a reverberant environment with a second delayed transient from a third azimuthal location. Results showed that the Franssen effect was either maintained or ``reset,'' but not reduced. The ongoing steady-state tone was perceived either at the initial-transient and then delayed-transient location, or at the initial transient location only. None of the listeners showed a location bias to the delayed transient tone when its frequency differed from the initial signal frequency or was replaced with noise. In additional conditions based on the ``false Haas effect,'' consonant-vowel pairs representing transient and steady-state signals were segregated contralaterally in a reverberant space. Results showed no resemblance to the Franssen effect. In general, results indicated that the role of attention is fundamental to the localization of an ongoing stimulus. [Work supported by NIH.

  4. Delay Choice vs. Delay Maintenance: Different Measures of Delayed Gratification in Capuchin Monkeys (Cebus apella)

    OpenAIRE

    Addessi, Elsa; Paglieri, Fabio; Beran, Michael J.; Evans, Theodore A.; Macchitella, Luigi; De Petrillo, Francesca; Focaroli, Valentina

    2013-01-01

    Delaying gratification involves two components: (i) delay choice (selecting a delayed reward over an immediate one), and (ii) delay maintenance (sustaining the decision to delay gratification even if the immediate reward is available during the delay). In primates, two tasks most commonly have explored these components, the Intertemporal choice task and the Accumulation task. It is unclear whether these tasks provide equivalent measures of delay of gratification. Here, we compared the perform...

  5. The Relevance of the Dynamic Stall Effect for Transient

    DEFF Research Database (Denmark)

    Jauch, Clemens; Sørensen, Poul; Bak-Jensen, Birgitte

    2005-01-01

    This article describes a methodology to quantify the influence of dynamic stall on transient fault operations of active-stall turbines. The model of the dynamic stall effect is introduced briefly. The behaviour of the dynamic stall model during a transient fault operation is described...... mathematically, and from this its effect quantified. Two quantities are chosen to describe the influence of the dynamic stall effect: one is active power and the other is time delay. Subsequently a transient fault scenario is simulated with and without the dynamic stall effect and the differences discussed. From...... this comparison, the conclusion is drawn that the dynamic stall effect has some influence on the post-fault behaviour of the wind turbine, and it is hence suggested that the dynamic stall effect is considered if an active-stall wind turbine is to be modelled realistically....

  6. Delayed Puberty (For Teens)

    Science.gov (United States)

    ... developed later than usual, too. This is called constitutional delay (or being a late bloomer), and it ... eventually — and even when you believe they're right — it's difficult to wait for something that can ...

  7. Delayed Sequence Intubation

    DEFF Research Database (Denmark)

    Weingart, Scott D; Trueger, N Seth; Wong, Nelson

    2015-01-01

    , patients were paralyzed and intubated. The primary outcome of this study was the difference in oxygen saturations after maximal attempts at preoxygenation before delayed sequence intubation compared with saturations just before intubation. Predetermined secondary outcomes and complications were also...... assessed. RESULTS: A total of 62 patients were enrolled: 19 patients required delayed sequence intubation to allow nonrebreather mask, 39 patients required it to allow NIPPV, and 4 patients required it for nasogastric tube placement. Saturations increased from a mean of 89.9% before delayed sequence...... intubation to 98.8% afterward, with an increase of 8.9% (95% confidence interval 6.4% to 10.9%). Thirty-two patients were in a predetermined group with high potential for critical desaturation (pre-delayed sequence intubation saturations ≤93%). All of these patients increased their saturations post...

  8. Delayed puberty in boys

    Science.gov (United States)

    ... Allan CA, McLachlan RI. Androgen deficiency disorders. In: Jameson JL, De Groot LJ, de Kretser DM, et ... 350. Haddad NG, Eugster EA. Delayed puberty. In: Jameson JL, De Groot LJ, de Kretser DM, et ...

  9. Calcium signalling silencing in atrial fibrillation.

    Science.gov (United States)

    Greiser, Maura

    2017-06-15

    Subcellular calcium signalling silencing is a novel and distinct cellular and molecular adaptive response to rapid cardiac activation. Calcium signalling silencing develops during short-term sustained rapid atrial activation as seen clinically during paroxysmal atrial fibrillation (AF). It is the first 'anti-arrhythmic' adaptive response in the setting of AF and appears to counteract the maladaptive changes that lead to intracellular Ca(2+) signalling instability and Ca(2+) -based arrhythmogenicity. Calcium signalling silencing results in a failed propagation of the [Ca(2+) ]i signal to the myocyte centre both in patients with AF and in a rabbit model. This adaptive mechanism leads to a substantial reduction in the expression levels of calcium release channels (ryanodine receptors, RyR2) in the sarcoplasmic reticulum, and the frequency of Ca(2+) sparks and arrhythmogenic Ca(2+) waves remains low. Less Ca(2+) release per [Ca(2+) ]i transient, increased fast Ca(2+) buffering strength, shortened action potentials and reduced L-type Ca(2+) current contribute to a substantial reduction of intracellular [Na(+) ]. These features of Ca(2+) signalling silencing are distinct and in contrast to the changes attributed to Ca(2+) -based arrhythmogenicity. Some features of Ca(2+) signalling silencing prevail in human AF suggesting that the Ca(2+) signalling 'phenotype' in AF is a sum of Ca(2+) stabilizing (Ca(2+) signalling silencing) and Ca(2+) destabilizing (arrhythmogenic unstable Ca(2+) signalling) factors. Calcium signalling silencing is a part of the mechanisms that contribute to the natural progression of AF and may limit the role of Ca(2+) -based arrhythmogenicity after the onset of AF. © 2017 The Authors. The Journal of Physiology © 2017 The Physiological Society.

  10. Calcium sensing in exocytosis

    DEFF Research Database (Denmark)

    Gustavsson, Natalia; Wu, Bingbing; Han, Weiping

    2012-01-01

    Neurotransmitters, neuropeptides and hormones are released through regulated exocytosis of synaptic vesicles and large dense core vesicles. This complex and highly regulated process is orchestrated by SNAREs and their associated proteins. The triggering signal for regulated exocytosis is usually...... an increase in intracellular calcium levels. Besides the triggering role, calcium signaling modulates the precise amount and kinetics of vesicle release. Thus, it is a central question to understand the molecular machineries responsible for calcium sensing in exocytosis. Here we provide an overview of our...

  11. Transient Go: A Mobile App for Transient Astronomy Outreach

    Science.gov (United States)

    Crichton, D.; Mahabal, A.; Djorgovski, S. G.; Drake, A.; Early, J.; Ivezic, Z.; Jacoby, S.; Kanbur, S.

    2016-12-01

    Augmented Reality (AR) is set to revolutionize human interaction with the real world as demonstrated by the phenomenal success of `Pokemon Go'. That very technology can be used to rekindle the interest in science at the school level. We are in the process of developing a prototype app based on sky maps that will use AR to introduce different classes of astronomical transients to students as they are discovered i.e. in real-time. This will involve transient streams from surveys such as the Catalina Real-time Transient Survey (CRTS) today and the Large Synoptic Survey Telescope (LSST) in the near future. The transient streams will be combined with archival and latest image cut-outs and other auxiliary data as well as historical and statistical perspectives on each of the transient types being served. Such an app could easily be adapted to work with various NASA missions and NSF projects to enrich the student experience.

  12. Dynamic and static calcium gradients inside large snail (Helix aspersa) neurones detected with calcium-sensitive microelectrodes.

    Science.gov (United States)

    Thomas, Roger C; Postma, Marten

    2007-04-01

    We have used quartz Ca2+-sensitive microelectrodes (CASMs) in large voltage-clamped snail neurones to investigate the inward spread of Ca2+ after a brief depolarisation. Both steady state and [Ca2+]i transients changed with depth of penetration. When the CASM tip was within 20 microm of the far side of the cell the [Ca2+]i transient time to peak was 4.4+/-0.5s, rising to 14.7+/-0.7s at a distance of 80 microm. We estimate that the Ca2+ transients travelled centripetally at an average speed of 6 microm2 s(-1) and decreased in size by half over a distance of about 45 microm. Cyclopiazonic acid had little effect on the size and time to peak of Ca2+ transients but slowed their recovery significantly. This suggests that the endoplasmic reticulum curtails rather than reinforces the transients. Injecting the calcium buffer BAPTA made the Ca2+ transients more uniform in size and increased their times to peak and rates of recovery near the membrane. We have developed a computational model for the transients, which includes diffusion, uptake and Ca2+ extrusion. Good fits were obtained with a rather large apparent diffusion coefficient of about 90+/-20 microm2 s(-1). This may assist fast recovery by extrusion.

  13. Bone repair in calcium-deficient rats: comparison of xylitol+calcium carbonate with calcium carbonate, calcium lactate and calcium citrate on the repletion of calcium.

    Science.gov (United States)

    Hämäläinen, M M

    1994-06-01

    The potential value of xylitol in calcium therapy was evaluated by comparing the effect of dietary xylitol (50 g/kg diet) + calcium carbonate with the effects of calcium carbonate, calcium lactate and calcium citrate on bone repair of young male rats after the rats consumed for 3 wk a calcium-deficient diet (0.2 g Ca/kg diet). After this calcium-depletion period, the rats were fed for 2 wk one of four diets, each containing 5 g Ca/kg diet as one of the four dietary calcium sources. The diet of the control animals was supplemented with CaCO3 (5 g Ca/kg diet) throughout the study. The Ca-deficient rats showed low bone mass, low serum calcium and high serum 1,25-dihydroxycholecalciferol, parathyroid hormone (1-34 fraction) and osteocalcin concentrations. They also excreted magnesium, phosphate and hydroxyproline in the urine in high concentrations, and had high bone alkaline phosphatase and tartrate-resistant acid phosphatase activities. Most of these changes were reversed by the administered of the calcium salts. The highest recoveries of femoral dry weight, calcium, magnesium and phosphate were observed in the groups receiving xylitol+CaCO3 and calcium lactate. Calcium lactate and calcium citrate caused low serum phosphate concentration compared with rats receiving CaCO3 and with the age-matched Ca-replete controls. Xylitol-treated rats excreted more calcium and magnesium in urine than did the other rats, probably due to increased absorption of these minerals from the gut. These results suggest that dietary xylitol improves the bioavailability of calcium salts.

  14. Calcium – how and why?

    Indian Academy of Sciences (India)

    Unknown

    Calcium is among the most commonly used ions, in a multitude of biological functions, so much so that it is impossible to imagine life without calcium. In this article I have attempted to address the question as to how calcium has achieved this status with a brief mention of the history of calcium research in biology. It appears ...

  15. Calcium and Your Child

    Science.gov (United States)

    ... Milk Allergy Figuring Out Food Labels What's a Vegetarian? Osteoporosis Minerals Your Bones Mineral Chart Vitamin D ... Need to Drink Milk? Lactose Intolerance Becoming a Vegetarian Soy Foods and Health Calcium Bones, Muscles, and ...

  16. Stoichiometry of Calcium Medicines

    Science.gov (United States)

    Pinto, Gabriel

    2005-01-01

    The topic of calcium supplement and its effects on human lives is presented in the way of questions to the students. It enables the students to realize the relevance of chemistry outside the classroom surrounding.

  17. Magnesium, calcium and cancer

    National Research Council Canada - National Science Library

    Anghileri, Leopoldo J

    2009-01-01

    Magnesium ion (Mg(2+)) and calcium ion (Ca(2+)) control a diverse and important range of cellular processes, such as gene transcription, cell proliferation, neoplastic transformation, immune response and therapeutic treatment...

  18. Frequency-Domain Transient Imaging.

    Science.gov (United States)

    Jingyu Lin; Yebin Liu; Jinli Suo; Qionghai Dai

    2017-05-01

    A transient image is the optical impulse response of a scene, which also visualizes the propagation of light during an ultra-short time interval. In contrast to the previous transient imaging which samples in the time domain using an ultra-fast imaging system, this paper proposes transient imaging in the frequency domain using a multi-frequency time-of-flight (ToF) camera. Our analysis reveals the Fourier relationship between transient images and the measurements of a multi-frequency ToF camera, and identifies the causes of the systematic error-non-sinusoidal and frequency-varying waveforms and limited frequency range of the modulation signal. Based on the analysis we propose a novel framework of frequency-domain transient imaging. By removing the systematic error and exploiting the harmonic components inside the measurements, we achieves high quality reconstruction results. Moreover, our technique significantly reduces the computational cost of ToF camera based transient image reconstruction, especially reduces the memory usage, such that it is feasible for the reconstruction of transient images at extremely small time steps. The effectiveness of frequency-domain transient imaging is tested on synthetic data, real data from the web, and real data acquired by our prototype camera.

  19. Pressure transients in pipeline systems

    DEFF Research Database (Denmark)

    Voigt, Kristian

    1998-01-01

    This text is to give an overview of the necessary background to do investigation of pressure transients via simulations. It will describe briefly the Method of Characteristics which is the defacto standard for simulating pressure transients. Much of the text has been adopted from the book Pressure...

  20. Dissociation of charge movement from calcium release and calcium current in skeletal myotubes by gabapentin.

    Science.gov (United States)

    Alden, Kris J; García, Jesús

    2002-09-01

    The skeletal muscle L-type calcium channel or dihydropyridine receptor (DHPR) plays an integral role in excitation-contraction (E-C) coupling. Its activation initiates three sequential events: charge movement (Q(r)), calcium release, and calcium current (I(Ca,L)). This relationship suggests that changes in Q(r) might affect release and I(Ca,L). Here we studied the effect of gabapentin (GBP) on the three events generated by DHPRs in skeletal myotubes in culture. GBP specifically binds to the alpha(2)/delta(1) subunit of the brain and skeletal muscle DHPR. Myotubes were stimulated with a protocol that included a depolarizing prepulse to inactivate voltage-dependent proteins other than DHPRs. Gabapentin (50 microM) significantly increased Q(r) while decreasing the rate of rise of calcium transients. Gabapentin also reduced the maximum amplitude of the I(Ca,L) (as we previously reported) without modifying the kinetics of activation. Exposure of GBP-treated myotubes to 10 microM nifedipine prevented the increase of Q(r) promoted by this drug, indicating that the extra charge recorded originated from DHPRs. Our data suggest that GBP dissociates the functions of the DHPR from the initial voltage-sensing step and implicates a role for the alpha(2)/delta(1) subunit in E-C coupling.

  1. [Calcium suppletion for patients who use gastric acid inhibitors: calcium citrate or calcium carbonate?].

    NARCIS (Netherlands)

    Jonge, H.J. de; Gans, R.O.; Huls, G.A.

    2012-01-01

    Various calcium supplements are available for patients who have an indication for calcium suppletion. American guidelines and UpToDate recommend prescribing calcium citrate to patients who use antacids The rationale for this advice is that water-insoluble calcium carbonate needs acid for adequate

  2. Applied hydraulic transients

    CERN Document Server

    Chaudhry, M Hanif

    2014-01-01

    This book covers hydraulic transients in a comprehensive and systematic manner from introduction to advanced level and presents various methods of analysis for computer solution. The field of application of the book is very broad and diverse and covers areas such as hydroelectric projects, pumped storage schemes, water-supply systems, cooling-water systems, oil pipelines and industrial piping systems. Strong emphasis is given to practical applications, including several case studies, problems of applied nature, and design criteria. This will help design engineers and introduce students to real-life projects. This book also: ·         Presents modern methods of analysis suitable for computer analysis, such as the method of characteristics, explicit and implicit finite-difference methods and matrix methods ·         Includes case studies of actual projects ·         Provides extensive and complete treatment of governed hydraulic turbines ·         Presents design charts, desi...

  3. Calcium in plant cells

    Directory of Open Access Journals (Sweden)

    V. V. Schwartau

    2014-04-01

    Full Text Available The paper gives the review on the role of calcium in many physiological processes of plant organisms, including growth and development, protection from pathogenic influences, response to changing environmental factors, and many other aspects of plant physiology. Initial intake of calcium ions is carried out by Ca2+-channels of plasma membrane and they are further transported by the xylem owing to auxins’ attractive ability. The level of intake and selectivity of calcium transport to ove-ground parts of the plant is controlled by a symplast. Ca2+enters to the cytoplasm of endoderm cells through calcium channels on the cortical side of Kaspary bands, and is redistributed inside the stele by the symplast, with the use of Ca2+-АТPases and Ca2+/Н+-antiports. Owing to regulated expression and activity of these calcium transporters, calclum can be selectively delivered to the xylem. Important role in supporting calcium homeostasis is given to the vacuole which is the largest depo of calcium. Regulated quantity of calcium movement through the tonoplast is provided by a number of potential-, ligand-gated active transporters and channels, like Ca2+-ATPase and Ca2+/H+ exchanger. They are actively involved in the inactivation of the calcium signal by pumping Ca2+ to the depo of cells. Calcium ATPases are high affinity pumps that efficiently transfer calcium ions against the concentration gradient in their presence in the solution in nanomolar concentrations. Calcium exchangers are low affinity, high capacity Ca2+ transporters that are effectively transporting calcium after raising its concentration in the cell cytosol through the use of protons gradients. Maintaining constant concentration and participation in the response to stimuli of different types also involves EPR, plastids, mitochondria, and cell wall. Calcium binding proteins contain several conserved sequences that provide sensitivity to changes in the concentration of Ca2+ and when you

  4. [Microbial geochemical calcium cycle].

    Science.gov (United States)

    Zavarzin, G A

    2002-01-01

    The participation of microorganisms in the geochemical calcium cycle is the most important factor maintaining neutral conditions on the Earth. This cycle has profound influence on the fate of inorganic carbon, and, thereby, on the removal of CO2 from the atmosphere. The major part of calcium deposits was formed in the Precambrian, when prokaryotic biosphere predominated. After that, calcium recycling based on biogenic deposition by skeletal organisms became the main process. Among prokaryotes, only a few representatives, e.g., cyanobacteria, exhibit a special calcium function. The geochemical calcium cycle is made possible by the universal features of bacteria involved in biologically mediated reactions and is determined by the activities of microbial communities. In the prokaryotic system, the calcium cycle begins with the leaching of igneous rock predominantly through the action of the community of organotrophic organisms. The release of carbon dioxide to the soil air by organotrophic aerobes leads to leaching with carbonic acid and soda salinization. Under anoxic conditions, of major importance is the organic acid production by primary anaerobes (fermentative microorganisms). Calcium carbonate is precipitated by secondary anaerobes (sulfate reducers) and to a smaller degree by methanogens. The role of the cyanobacterial community in carbonate deposition is exposed by stromatolites, which are the most common organo-sedimentary Precambrian structures. Deposition of carbonates in cyanobacterial mats as a consequence of photoassimilation of CO2 does not appear to be a significant process. It is argued that carbonates were deposited at the boundary between the "soda continent", which emerged as a result of subaerial leaching with carbonic acid, and the ocean containing Ca2+. Such ecotones provided favorable conditions for the development of the benthic cyanobacterial community, which was a precursor of stromatolites.

  5. Stripe delay filters

    OpenAIRE

    Zakharov, Alexander V.; Ilchenko, Mykhailo Ye.; Trubarov, Igor V.; Pinchuk, Ludmila S.

    2016-01-01

    There are considered constructions of microsized stripe delay filters, which are realized on a basis of ceramic materials with high dielectric permittivity. Delay time of non-minimal phase filters is 7–12 ns at frequencies of 1900 MHz with relative bandwidth of 3.6–3.85%. Filters dimensions are comparable with ones used in portable communication devices. Dimensions of researched three-resonator filter at frequency of 1900 MHz are 8.4×5×2 mm with material dielectric permittivity εr = 92, and 5...

  6. Eliminating common PACU delays.

    Science.gov (United States)

    Jenkins, Jamie

    2007-01-01

    This article discusses how one hospital identified patient flow delays in its PACU By using lean methods focused on eliminating waste, the team was able to improve patient flow. Lean thinking required the team to keep issues that were important to patients at top of mind. The improvements not only saved staff time, but they also helped the department prepare for the addition of six beds by focusing on methods to eliminate delays. The team, assigned by the vice president of surgical services, included a process engineer two decision support analysts, the PACU charge nurse, the nursing manager and ad hoc department nurses. The team recommended and implemented changes to improve operational effectiveness.

  7. Electromagnetic transients in power cables

    CERN Document Server

    da Silva, Filipe Faria

    2013-01-01

    From the more basic concepts to the most advanced ones where long and laborious simulation models are required, Electromagnetic Transients in Power Cables provides a thorough insight into the study of electromagnetic transients and underground power cables. Explanations and demonstrations of different electromagnetic transient phenomena are provided, from simple lumped-parameter circuits to complex cable-based high voltage networks, as well as instructions on how to model the cables.Supported throughout by illustrations, circuit diagrams and simulation results, each chapter contains exercises,

  8. Machine Classification of Transient Images

    Science.gov (United States)

    Buisson, Lise Du; Sivanandam, Navin; Bassett, Bruce A.; Smith, Mathew

    2014-05-01

    Using transient imaging data from the 2nd and 3rd years of the SDSS supernova survey, we apply various machine learning techniques to the problem of classifying transients (e.g. SNe) from artefacts, one of the first steps in any transient detection pipeline, and one that is often still carried out by human scanners. Using features mostly obtained from PCA, we show that we can match human levels of classification success, and find that a K-nearest neighbours algorithm and SkyNet perform best, while the Naive Bayes, SVM and minimum error classifier have performances varying from slightly to significantly worse.

  9. Nuclear calcium signalling in the regulation of brain function.

    Science.gov (United States)

    Bading, Hilmar

    2013-09-01

    Synaptic activity initiates biochemical processes that have various outcomes, including the formation of memories, increases in neuronal survival and the development of chronic pain and addiction. Virtually all activity-induced, long-lasting adaptations of brain functions require a dialogue between synapses and the nucleus that results in changes in gene expression. Calcium signals that are induced by synaptic activity and propagate into the nucleus are a major route for synapse-to-nucleus communication. Recent findings indicate that diverse forms of neuroadaptation require calcium transients in the nucleus to switch on the necessary genomic programme. Deficits in nuclear calcium signalling as a result of a reduction in synaptic activity or increased extrasynaptic NMDA receptor signalling may underlie the aetiologies of various diseases, including neurodegeneration and cognitive dysfunction.

  10. Effects of gastrin on calcium homeostasis in chickens

    Energy Technology Data Exchange (ETDEWEB)

    Persson, P.; Gagnemo-Persson, R.; Orberg, J.; Chen, D.; Hakanson, R. (University of Lund (Sweden))

    1991-09-01

    As in the rat, gastrin and an extract of the acid-producing part of the stomach (proventriculus) were found to lower the blood Ca2+ concentration in the chicken. Furthermore, gastrin enhanced the uptake of 45Ca into the femur. It has been suggested previously that gastrin causes hypocalcemia in the rat by releasing gastrocalcin, a hypothetical hormone thought to reside in the acid-producing part of the stomach. The results of the present study in the chicken are in agreement with this concept. Not only exogenous, but also endogenous gastrin lowered blood calcium levels. Thus, the serum gastrin concentration was increased in response to ranitidine-evoked blockade of the gastric acid output; the rise in gastrin was associated with a transient drop in blood calcium. Also, food intake produced a rise in the serum gastrin concentration and a transient drop in blood calcium. However, injection of ranitidine or food intake in proventriclectomized (acid-producing part of the stomach extirpated) chickens failed to lower blood calcium, supporting the view that the gastrin-evoked hypocalcemia depends upon an agent in the gastric (proventriculus) mucosa. The authors suggest that endogenous and exogenous gastrin evoke hypocalcemia in the chicken by the same mechanism as that which has been postulated in the rat, i.e. by mobilization of the candidate hormone gastrocalcin from endocrine cells in the acid-producing gastric mucosa.

  11. Calcium orthophosphates in dentistry.

    Science.gov (United States)

    Dorozhkin, Sergey V

    2013-06-01

    Dental caries, also known as tooth decay or a cavity, remains a major public health problem in the most communities even though the prevalence of disease has decreased since the introduction of fluorides for dental care. Therefore, biomaterials to fill dental defects appear to be necessary to fulfill customers' needs regarding the properties and the processing of the products. Bioceramics and glass-ceramics are widely used for these purposes, as dental inlays, onlays, veneers, crowns or bridges. Calcium orthophosphates belong to bioceramics but they have some specific advantages over other types of bioceramics due to a chemical similarity to the inorganic part of both human and mammalian bones and teeth. Therefore, calcium orthophosphates (both alone and as components of various formulations) are used in dentistry as both dental fillers and implantable scaffolds. This review provides brief information on calcium orthophosphates and describes in details current state-of-the-art on their applications in dentistry and dentistry-related fields. Among the recognized dental specialties, calcium orthophosphates are most frequently used in periodontics; however, the majority of the publications on calcium orthophosphates in dentistry are devoted to unspecified "dental" fields.

  12. Induction of epithelial-mesenchymal transition (EMT) in breast cancer cells is calcium signal dependent.

    Science.gov (United States)

    Davis, F M; Azimi, I; Faville, R A; Peters, A A; Jalink, K; Putney, J W; Goodhill, G J; Thompson, E W; Roberts-Thomson, S J; Monteith, G R

    2014-05-01

    Signals from the tumor microenvironment trigger cancer cells to adopt an invasive phenotype through epithelial-mesenchymal transition (EMT). Relatively little is known regarding key signal transduction pathways that serve as cytosolic bridges between cell surface receptors and nuclear transcription factors to induce EMT. A better understanding of these early EMT events may identify potential targets for the control of metastasis. One rapid intracellular signaling pathway that has not yet been explored during EMT induction is calcium. Here we show that stimuli used to induce EMT produce a transient increase in cytosolic calcium levels in human breast cancer cells. Attenuation of the calcium signal by intracellular calcium chelation significantly reduced epidermal growth factor (EGF)- and hypoxia-induced EMT. Intracellular calcium chelation also inhibited EGF-induced activation of signal transducer and activator of transcription 3 (STAT3), while preserving other signal transduction pathways such as Akt and extracellular signal-regulated kinase 1/2 (ERK1/2) phosphorylation. To identify calcium-permeable channels that may regulate EMT induction in breast cancer cells, we performed a targeted siRNA-based screen. We found that transient receptor potential-melastatin-like 7 (TRPM7) channel expression regulated EGF-induced STAT3 phosphorylation and expression of the EMT marker vimentin. Although intracellular calcium chelation almost completely blocked the induction of many EMT markers, including vimentin, Twist and N-cadherin, the effect of TRPM7 silencing was specific for vimentin protein expression and STAT3 phosphorylation. These results indicate that TRPM7 is a partial regulator of EMT in breast cancer cells, and that other calcium-permeable ion channels are also involved in calcium-dependent EMT induction. In summary, this work establishes an important role for the intracellular calcium signal in the induction of EMT in human breast cancer cells. Manipulation of

  13. T-Type Calcium Channels Are Required to Maintain Viability of Neural Progenitor Cells.

    Science.gov (United States)

    Kim, Ji-Woon; Oh, Hyun Ah; Lee, Sung Hoon; Kim, Ki Chan; Eun, Pyung Hwa; Ko, Mee Jung; Gonzales, Edson Luck T; Seung, Hana; Kim, Seonmin; Bahn, Geon Ho; Shin, Chan Young

    2018-02-21

    T-type calcium channels are low voltage-activated calcium channels that evoke small and transient calcium currents. Recently, T-type calcium channels have been implicated in neurodevelopmental disorders such as autism spectrum disorder and neural tube defects. However, their function during embryonic development is largely unknown. Here, we investigated the function and expression of T-type calcium channels in embryonic neural progenitor cells (NPCs). First, we compared the expression of T-type calcium channel subtypes (CaV3.1, 3.2, and 3.3) in NPCs and differentiated neural cells (neurons and astrocytes). We detected all subtypes in neurons but not in astrocytes. In NPCs, CaV3.1 was the dominant subtype, whereas CaV3.2 was weakly expressed, and CaV3.3 was not detected. Next, we determined CaV3.1 expression levels in the cortex during early brain development. Expression levels of CaV3.1 in the embryonic period were transiently decreased during the perinatal period and increased at postnatal day 11. We then pharmacologically blocked T-type calcium channels to determine the effects in neuronal cells. The blockade of T-type calcium channels reduced cell viability, and induced apoptotic cell death in NPCs but not in differentiated astrocytes. Furthermore, blocking T-type calcium channels rapidly reduced AKT-phosphorylation (Ser473) and GSK3β-phosphorylation (Ser9). Our results suggest that T-type calcium channels play essential roles in maintaining NPC viability, and T-type calcium channel blockers are toxic to embryonic neural cells, and may potentially be responsible for neurodevelopmental disorders.

  14. Sustained Perceptual Deficits from Transient Sensory Deprivation

    Science.gov (United States)

    Sanes, Dan H.

    2015-01-01

    displays an increased vulnerability to the sensory environment. Here, we identify a precise developmental window during which mild hearing loss affects the maturation of an auditory perceptual cue that is known to support animal communication, including human speech. Furthermore, animals reared with transient hearing loss display deficits in perceptual learning. Our results suggest that speech and language delays associated with transient or permanent childhood hearing loss may be accounted for, in part, by deficits in central auditory processing mechanisms. PMID:26224865

  15. Delayed breast implant reconstruction

    DEFF Research Database (Denmark)

    Hvilsom, Gitte B.; Hölmich, Lisbet R.; Steding-Jessen, Marianne

    2012-01-01

    We evaluated the association between radiation therapy and severe capsular contracture or reoperation after 717 delayed breast implant reconstruction procedures (288 1- and 429 2-stage procedures) identified in the prospective database of the Danish Registry for Plastic Surgery of the Breast during...... reconstruction approaches other than implants should be seriously considered among women who have received radiation therapy....

  16. Permissible Delay in Payments

    Directory of Open Access Journals (Sweden)

    Yung-Fu Huang

    2007-01-01

    Full Text Available The main purpose of this paper wants to investigate the optimal retailer's lot-sizing policy with two warehouses under partially permissible delay in payments within the economic order quantity (EOQ framework. In this paper, we want to extend that fully permissible delay in payments to the supplier would offer the retailer partially permissible delay in payments. That is, the retailer must make a partial payment to the supplier when the order is received. Then the retailer must pay off the remaining balance at the end of the permissible delay period. In addition, we want to add the assumption that the retailer's storage space is limited. That is, the retailer will rent the warehouse to store these exceeding items when the order quantity is larger than retailer's storage space. Under these conditions, we model the retailer's inventory system as a cost minimization problem to determine the retailer's optimal cycle time and optimal order quantity. Three theorems are developed to efficiently determine the optimal replenishment policy for the retailer. Finally, numerical examples are given to illustrate these theorems and obtained a lot of managerial insights.

  17. Delayed visual maturation.

    OpenAIRE

    Harel, S; Holtzman, M; Feinsod, M

    1983-01-01

    Three infants, recognised as blind during the first 4 months of life, were found to be normal on neurological and ophthalmological examinations. Visual electro-diagnostic studies showed normal retinal responses, but delayed conduction velocities and impaired visually-evoked responses over the occipital cortex. After age 6 months, normal vision developed gradually and all abnormalities disappeared.

  18. Delayed visual maturation.

    Science.gov (United States)

    Harel, S; Holtzman, M; Feinsod, M

    1983-01-01

    Three infants, recognised as blind during the first 4 months of life, were found to be normal on neurological and ophthalmological examinations. Visual electro-diagnostic studies showed normal retinal responses, but delayed conduction velocities and impaired visually-evoked responses over the occipital cortex. After age 6 months, normal vision developed gradually and all abnormalities disappeared. PMID:6189454

  19. Spatially discordant alternans in cardiac tissue: role of calcium cycling.

    Science.gov (United States)

    Sato, Daisuke; Shiferaw, Yohannes; Garfinkel, Alan; Weiss, James N; Qu, Zhilin; Karma, Alain

    2006-09-01

    Spatially discordant alternans, where the action potential duration (APD) and intracellular calcium transient (Ca(i)) alternate with opposite phase in different regions of tissue, is known to promote wave break and reentry. However, this phenomenon is not completely understood. It is known that alternans at the cellular level can be caused by dynamical instabilities arising from either membrane voltage (V(m)) attributable to steep APD restitution or to calcium (Ca) cycling. Here, we used a mathematical model of intracellular Ca cycling, coupled with membrane ion currents, to investigate the dynamics of V(m) and Ca(i) transient alternans in an isolated cell, in two electrotonically coupled cells, and in 1D spatially homogeneous tissue. Our main finding is a novel instability mechanism in which the bidirectional coupling of V(m) and Ca(i) can drive the Ca(i) transient of two neighboring cells to be out of phase. This instability is manifested in cardiac tissue by the dynamical formation of spatially discordant alternans. In this case, Ca(i) transient alternans can reverse phase over a length scale of one cell, whereas APD alternans reverses phase over a much longer length scale set by the electrotonic coupling. We analyze this mechanism in detail and show that it is a robust consequence of experimentally established properties of the bidirectional coupling between Ca cycling and V(m) dynamics. Finally, we address the experimental relevance of these findings and suggest physiological conditions under which these patterns can be observed.

  20. Electromagnetic Transients in Power Cables

    DEFF Research Database (Denmark)

    Silva, Filipe Faria Da; Bak, Claus Leth

    of electromagnetic phenomena associated to their operation, among them electromagnetic transients, increased as well. Transient phenomena have been studied since the beginning of power systems, at first using only analytical approaches, which limited studies to more basic phenomena; but as computational tools became...... more powerful, the analyses started to expand for the more complex phenomena. Being old phenomena, electromagnetic transients are covered in many publications, and classic books such as the 40-year-old Greenwood’s ‘‘Electric Transients in Power Systems’’ are still used to this day. However...... example.However, the book is not only intended for students . It can also be used by engineers who work in this area and need to understand the challenges/problems they are facing or who need to learn how to prepare their simulation models as well as their function. It also shows how to calculate...

  1. Transient heating of moving objects

    Directory of Open Access Journals (Sweden)

    E.I. Baida

    2014-06-01

    Full Text Available A mathematical model of transient and quasistatic heating of moving objects by various heat sources is considered. The mathematical formulation of the problem is described, examples of thermal calculation given.

  2. Transient thyrotoxicosis during nivolumab treatment

    NARCIS (Netherlands)

    van Kooten, M. J.; van den Berg, G.; Glaudemans, A. W. J. M.; Hiltermann, T. J. N.; Groen, H. J. M.; Rutgers, A.; Links, T. P.

    Two patients presented with transient thyrotoxicosis within 2-4 weeks after starting treatment with nivolumab. This thyrotoxicosis turned into hypothyroidism within 6-8 weeks. Temporary treatment with a beta blocker may be sufficient.

  3. Transient Tsunamis in Lakes

    Science.gov (United States)

    Couston, L.; Mei, C.; Alam, M.

    2013-12-01

    A large number of lakes are surrounded by steep and unstable mountains with slopes prone to failure. As a result, landslides are likely to occur and impact water sitting in closed reservoirs. These rare geological phenomena pose serious threats to dam reservoirs and nearshore facilities because they can generate unexpectedly large tsunami waves. In fact, the tallest wave experienced by contemporary humans occurred because of a landslide in the narrow bay of Lituya in 1958, and five years later, a deadly landslide tsunami overtopped Lake Vajont's dam, flooding and damaging villages along the lakefront and in the Piave valley. If unstable slopes and potential slides are detected ahead of time, inundation maps can be drawn to help people know the risks, and mitigate the destructive power of the ensuing waves. These maps give the maximum wave runup height along the lake's vertical and sloping boundaries, and can be obtained by numerical simulations. Keeping track of the moving shorelines along beaches is challenging in classical Eulerian formulations because the horizontal extent of the fluid domain can change over time. As a result, assuming a solid slide and nonbreaking waves, here we develop a nonlinear shallow-water model equation in the Lagrangian framework to address the problem of transient landslide-tsunamis. In this manner, the shorelines' three-dimensional motion is part of the solution. The model equation is hyperbolic and can be solved numerically by finite differences. Here, a 4th order Runge-Kutta method and a compact finite-difference scheme are implemented to integrate in time and spatially discretize the forced shallow-water equation in Lagrangian coordinates. The formulation is applied to different lake and slide geometries to better understand the effects of the lake's finite lengths and slide's forcing mechanism on the generated wavefield. Specifically, for a slide moving down a plane beach, we show that edge-waves trapped by the shoreline and free

  4. Calcium Signalling: Fishing Out Molecules of Mitochondrial Calcium Transport

    OpenAIRE

    Hajnóczky, György; Csordás, György

    2010-01-01

    Cellular energy metabolism, survival and death are controlled by mitochondrial calcium signals originating in the cytoplasm. Now, RNAi studies link three proteins — MICU1, NCLX and LETM1 — to the previously unknown molecular mechanism of mitochondrial calcium transport.

  5. Gravimetric Determination of Calcium as Calcium Carbonate Hydrate.

    Science.gov (United States)

    Henrickson, Charles H.; Robinson, Paul R.

    1979-01-01

    The gravimetric determination of calcium as calcium carbonate is described. This experiment is suitable for undergraduate quantitative analysis laboratories. It is less expensive than determination of chloride as silver chloride. (BB)

  6. Excessive signal transduction of gain-of-function variants of the calcium-sensing receptor (CaSR are associated with increased ER to cytosol calcium gradient.

    Directory of Open Access Journals (Sweden)

    Marianna Ranieri

    Full Text Available In humans, gain-of-function mutations of the calcium-sensing receptor (CASR gene are the cause of autosomal dominant hypocalcemia or type 5 Bartter syndrome characterized by an abnormality of calcium metabolism with low parathyroid hormone levels and excessive renal calcium excretion. Functional characterization of CaSR activating variants has been so far limited at demonstrating an increased sensitivity to external calcium leading to lower Ca-EC50. Here we combine high resolution fluorescence based techniques and provide evidence that for the efficiency of calcium signaling system, cells expressing gain-of-function variants of CaSR monitor cytosolic and ER calcium levels increasing the expression of the Sarco-Endoplasmic Reticulum Calcium-ATPase (SERCA and reducing expression of Plasma Membrane Calcium-ATPase (PMCA. Wild-type CaSR (hCaSR-wt and its gain-of-function (hCaSR-R990G; hCaSR-N124K variants were transiently transfected in HEK-293 cells. Basal intracellular calcium concentration was significantly lower in cells expressing hCaSR-wt and its gain of function variants compared to mock. In line, FRET studies using the D1ER probe, which detects [Ca2+]ER directly, demonstrated significantly higher calcium accumulation in cells expressing the gain of function CaSR variants compared to hCaSR-wt. Consistently, cells expressing activating CaSR variants showed a significant increase in SERCA activity and expression and a reduced PMCA expression. This combined parallel regulation in protein expression increases the ER to cytosol calcium gradient explaining the higher sensitivity of CaSR gain-of-function variants to external calcium. This control principle provides a general explanation of how cells reliably connect (and exacerbate receptor inputs to cell function.

  7. Excessive Signal Transduction of Gain-of-Function Variants of the Calcium-Sensing Receptor (CaSR) Are Associated with Increased ER to Cytosol Calcium Gradient

    Science.gov (United States)

    Di Mise, Annarita; Vezzoli, Giuseppe; Soldati, Laura; Svelto, Maria; Valenti, Giovanna

    2013-01-01

    In humans, gain-of-function mutations of the calcium-sensing receptor (CASR) gene are the cause of autosomal dominant hypocalcemia or type 5 Bartter syndrome characterized by an abnormality of calcium metabolism with low parathyroid hormone levels and excessive renal calcium excretion. Functional characterization of CaSR activating variants has been so far limited at demonstrating an increased sensitivity to external calcium leading to lower Ca-EC50. Here we combine high resolution fluorescence based techniques and provide evidence that for the efficiency of calcium signaling system, cells expressing gain-of-function variants of CaSR monitor cytosolic and ER calcium levels increasing the expression of the Sarco-Endoplasmic Reticulum Calcium-ATPase (SERCA) and reducing expression of Plasma Membrane Calcium-ATPase (PMCA). Wild-type CaSR (hCaSR-wt) and its gain-of-function (hCaSR-R990G; hCaSR-N124K) variants were transiently transfected in HEK-293 cells. Basal intracellular calcium concentration was significantly lower in cells expressing hCaSR-wt and its gain of function variants compared to mock. In line, FRET studies using the D1ER probe, which detects [Ca2+]ER directly, demonstrated significantly higher calcium accumulation in cells expressing the gain of function CaSR variants compared to hCaSR-wt. Consistently, cells expressing activating CaSR variants showed a significant increase in SERCA activity and expression and a reduced PMCA expression. This combined parallel regulation in protein expression increases the ER to cytosol calcium gradient explaining the higher sensitivity of CaSR gain-of-function variants to external calcium. This control principle provides a general explanation of how cells reliably connect (and exacerbate) receptor inputs to cell function. PMID:24244430

  8. Association of the Iγ and Iδ Charge Movement with Calcium Release in Frog Skeletal Muscle

    OpenAIRE

    Hui, Chiu Shuen

    2004-01-01

    Charge movement and calcium transient were measured simultaneously in stretched frog cut twitch fibers under voltage clamp, with the internal solution containing 20 mM EGTA plus added calcium and antipyrylazo III. When the nominal free [Ca2+]i was 10 nM, the shape of the broad Iγ hump in the ON segments of charge movement traces remained invariant when the calcium release rate was greatly diminished. When the nominal free [Ca2+]i was 50 nM, which was close to the physiological level, the Iγ h...

  9. Reactor transient analyses with KIN3D/PARTISN

    Energy Technology Data Exchange (ETDEWEB)

    Gabrielli, F.; Rineiski, A.; Maschek, W.; Marchetti, M. [Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)

    2013-07-01

    Efforts are going on at the Karlsruhe Institute of Technology (KIT) to extend the kinetics capability of the PARTISN code in order to run in parallel two- and three-dimensional transient analyses with the quasistatic method, while taking into account delayed neutrons. In the original code version, time-dependent transport problems are solved by employing a semi-implicit direct kinetics option, the delayed neutrons being not taken into account. The PARTISN 5.97 code has been extended and then coupled with KIN3D, a time-dependent model embedded in the ERANOS code system. In the coupled code, PARTISN 5.97 is used as neutron transport solver to perform transient analyses while employing direct and quasi-static kinetics options of KIN3D. The coupled code can be also applied for first-order and exact perturbation theory calculations. In the paper, the PARTISN 5.97 extensions and coupling procedure are described and the performances of the KIN3D/PARTISN coupled code are investigated by analyzing transients induced by a source-jerk in a three-dimensional ADS model driven by an external source. (authors)

  10. Transient critical heat flux and blowdown heat-transfer studies

    Energy Technology Data Exchange (ETDEWEB)

    Leung, J.C.

    1980-05-01

    Objective of this study is to give a best-estimate prediction of transient critical heat flux (CHF) during reactor transients and hypothetical accidents. To accomplish this task, a predictional method has been developed. Basically it involves the thermal-hydraulic calculation of the heated core with boundary conditions supplied from experimental measurements. CHF predictions were based on the instantaneous ''local-conditions'' hypothesis, and eight correlations (consisting of round-tube, rod-bundle, and transient correlations) were tested against most recent blowdown heat-transfer test data obtained in major US facilities. The prediction results are summarized in a table in which both CISE and Biasi correlations are found to be capable of predicting the early CHF of approx. 1 s. The Griffith-Zuber correlation is credited for its prediction of the delay CHF that occurs in a more tranquil state with slowly decaying mass velocity. In many instances, the early CHF can be well correlated by the x = 1.0 criterion; this is certainly indicative of an annular-flow dryout-type crisis. The delay CHF occurred at near or above 80% void fraction, and the success of the modified Zuber pool-boiling correlation suggests that this CHF is caused by flooding and pool-boiling type hydrodynamic crisis.

  11. Transient-absorption phases with strong probe and pump pulses

    Science.gov (United States)

    Becquet, Vadim; Cavaletto, Stefano M.

    2018-02-01

    The quantum dynamics of a system of Rb atoms, modeled by a V-type three-level system interacting with intense probe and pump pulses, are studied. The time-delay-dependent transient-absorption spectrum of an intense probe pulse is thus predicted, simulating pump-probe experiments in which this is preceded or followed by a strong pump pulse. Numerical results are interpreted in terms of an analytical model based on interaction operators, which quantify the transformation undergone by the system under the action of an intense pulse. The oscillating features of the resulting transient-absorption spectra, due to the coupling of several excited states, are thus interpreted in terms of the atomic population and phase changes imposed by the pump and probe pulses. Strong-field-induced phases and their influence on the resulting transient-absorption spectra are thereby investigated for different values of pump and probe intensities and frequencies, focusing on the atomic properties which are encoded in the absorption line shapes for positive and negative time delays.

  12. Children's Bone Health and Calcium

    Science.gov (United States)

    ... Email Share Dialog × Print Children's Bone Health and Calcium: Condition Information What is bone health and how ... straight, walk, run, and lead an active life. Calcium is one of the key dietary building blocks ...

  13. Impact of calcium signaling during infection of Neisseria meningitidis to human brain microvascular endothelial cells.

    Science.gov (United States)

    Asmat, Tauseef M; Tenenbaum, Tobias; Jonsson, Ann-Beth; Schwerk, Christian; Schroten, Horst

    2014-01-01

    The pili and outer membrane proteins of Neisseria meningitidis (meningococci) facilitate bacterial adhesion and invasion into host cells. In this context expression of meningococcal PilC1 protein has been reported to play a crucial role. Intracellular calcium mobilization has been implicated as an important signaling event during internalization of several bacterial pathogens. Here we employed time lapse calcium-imaging and demonstrated that PilC1 of meningococci triggered a significant increase in cytoplasmic calcium in human brain microvascular endothelial cells, whereas PilC1-deficient meningococci could not initiate this signaling process. The increase in cytosolic calcium in response to PilC1-expressing meningococci was due to efflux of calcium from host intracellular stores as demonstrated by using 2-APB, which inhibits the release of calcium from the endoplasmic reticulum. Moreover, pre-treatment of host cells with U73122 (phospholipase C inhibitor) abolished the cytosolic calcium increase caused by PilC1-expressing meningococci demonstrating that active phospholipase C (PLC) is required to induce calcium transients in host cells. Furthermore, the role of cytosolic calcium on meningococcal adherence and internalization was documented by gentamicin protection assay and double immunofluorescence (DIF) staining. Results indicated that chelation of intracellular calcium by using BAPTA-AM significantly impaired PilC1-mediated meningococcal adherence to and invasion into host endothelial cells. However, buffering of extracellular calcium by BAPTA or EGTA demonstrated no significant effect on meningococcal adherence to and invasion into host cells. Taken together, these results indicate that meningococci induce calcium release from intracellular stores of host endothelial cells via PilC1 and cytoplasmic calcium concentrations play a critical role during PilC1 mediated meningococcal adherence to and subsequent invasion into host endothelial cells.

  14. Impact of calcium signaling during infection of Neisseria meningitidis to human brain microvascular endothelial cells.

    Directory of Open Access Journals (Sweden)

    Tauseef M Asmat

    Full Text Available The pili and outer membrane proteins of Neisseria meningitidis (meningococci facilitate bacterial adhesion and invasion into host cells. In this context expression of meningococcal PilC1 protein has been reported to play a crucial role. Intracellular calcium mobilization has been implicated as an important signaling event during internalization of several bacterial pathogens. Here we employed time lapse calcium-imaging and demonstrated that PilC1 of meningococci triggered a significant increase in cytoplasmic calcium in human brain microvascular endothelial cells, whereas PilC1-deficient meningococci could not initiate this signaling process. The increase in cytosolic calcium in response to PilC1-expressing meningococci was due to efflux of calcium from host intracellular stores as demonstrated by using 2-APB, which inhibits the release of calcium from the endoplasmic reticulum. Moreover, pre-treatment of host cells with U73122 (phospholipase C inhibitor abolished the cytosolic calcium increase caused by PilC1-expressing meningococci demonstrating that active phospholipase C (PLC is required to induce calcium transients in host cells. Furthermore, the role of cytosolic calcium on meningococcal adherence and internalization was documented by gentamicin protection assay and double immunofluorescence (DIF staining. Results indicated that chelation of intracellular calcium by using BAPTA-AM significantly impaired PilC1-mediated meningococcal adherence to and invasion into host endothelial cells. However, buffering of extracellular calcium by BAPTA or EGTA demonstrated no significant effect on meningococcal adherence to and invasion into host cells. Taken together, these results indicate that meningococci induce calcium release from intracellular stores of host endothelial cells via PilC1 and cytoplasmic calcium concentrations play a critical role during PilC1 mediated meningococcal adherence to and subsequent invasion into host endothelial cells.

  15. Antagonistic modulatory roles of magnesium and calcium on release of endothelium-derived relaxing factor and smooth muscle tone.

    Science.gov (United States)

    Gold, M E; Buga, G M; Wood, K S; Byrns, R E; Chaudhuri, G; Ignarro, L J

    1990-02-01

    The objective of this study was to elucidate the mechanisms associated with the reciprocal relation between magnesium and calcium on vascular smooth muscle tone in bovine pulmonary artery and vein. Rapid removal of magnesium from Krebs-bicarbonate medium used to bathe isolated rings of precontracted artery or vein caused transient endothelium- and calcium-dependent relaxation and cyclic GMP accumulation. Both responses were antagonized by oxyhemoglobin, methylene blue, or superoxide anion and were enhanced by superoxide dismutase. The transient relaxation was followed by sustained endothelium-independent contraction. Endothelium-denuded vascular rings contracted in response to extracellular magnesium depletion without alteration in cyclic GMP levels. The data suggest that vascular endothelium-derived nitric oxide is responsible for the calcium-dependent relaxation elicited by extracellular magnesium depletion. Indeed, in bioassay cascade studies, magnesium removal from the medium used to perfuse intact artery or vein enhanced the formation and/or release of an endothelium-derived relaxing factor by calcium-dependent mechanisms. In the absence of both extracellular magnesium and calcium, calcium readdition caused transient endothelium-dependent relaxation and cyclic GMP accumulation, and both responses were abolished by oxyhemoglobin or methylene blue. In the presence of magnesium, however, readdition of calcium to calcium-depleted medium caused only contractile responses. Addition of magnesium to calcium-containing medium consistently caused endothelium- and cyclic GMP-independent relaxation that was not altered by oxyhemoglobin or methylene blue. Thus, magnesium and calcium elicit reciprocal or mutually antagonistic effects at the levels of both endothelium-derived relaxing factor formation and/or release and smooth muscle contraction. This relation may be of physiological importance, and the possibility that a reduction in circulating magnesium levels could lead

  16. Stable prenucleation calcium carbonate clusters

    OpenAIRE

    Gebauer, Denis; Völkel, Antje; Cölfen, Helmut

    2008-01-01

    Calcium carbonate forms scales, geological deposits, biominerals, and ocean sediments. Huge amounts of carbon dioxide are retained as carbonate ions, and calcium ions represent a major contribution to water hardness. Despite its relevance, little is known about the precipitation mechanism of calcium carbonate, and specified complex crystal structures challenge the classical view on nucleation considering the formation of metastable ion clusters. We demonstrate that dissolved calcium carbonate...

  17. PYK2: A Calcium-sensitive Protein Tyrosine Kinase Activated in Response to Fertilization of the Zebrafish Oocyte

    Science.gov (United States)

    Sharma, Dipika; Kinsey, William H.

    2012-01-01

    Fertilization begins with binding and fusion of a sperm with the oocyte, a process that triggers a high amplitude calcium transient which propagates through the oocyte and stimulates a series of preprogrammed signal transduction events critical for zygote development. Identification of the pathways downstream of this calcium transient remains an important step in understanding the basis of zygote quality. The present study demonstrates that the calcium-calmodulin sensitive protein tyrosine kinase PYK2 is a target of the fertilization-induced calcium transient in the zebrafish oocyte and that it plays an important role in actin-mediated events critical for sperm incorporation. At fertilization, PYK2 was activated initially at the site of sperm-oocyte interaction and was closely associated with actin filaments forming the fertilization cone. Later PYK2 activation was evident throughout the entire oocyte cortex, however activation was most intense over the animal hemisphere. Fertilization-induced PYK2 activation could be blocked by suppressing calcium transients in the ooplasm via injection of BAPTA as a calcium chelator. PYK2 activation could be artificially induced in unfertilized oocytes by injection of IP3 at concentrations sufficient to induce calcium release. Functionally, suppression of PYK2 activity by chemical inhibition or by injection of a dominant-negative construct encoding the N-terminal ERM domain of PKY2 inhibited formation of an organized fertilization cone and reduced the frequency of successful sperm incorporation. Together, the above findings support a model in which PYK2 responds to the fertilization-induced calcium transient by promoting reorganization of the cortical actin cytoskeleton to form the fertilization cone. PMID:23084926

  18. Assay for calcium channels

    Energy Technology Data Exchange (ETDEWEB)

    Glossmann, H.; Ferry, D.R.

    1985-01-01

    This chapter focuses on biochemical assays for Ca/sup 2 +/-selective channels in electrically excitable membranes which are blocked in electrophysiological and pharmacological experiments by verapamil, 1,4-dihydropyridines, diltiazen (and various other drugs), as well as inorganic di- or trivalent cations. The strategy employed is to use radiolabeled 1,4-dihydropyridine derivatives which block calcium channels with ED/sub 50/ values in the nanomolar range. Although tritiated d-cis-diltiazem and verapamil can be used to label calcium channels, the 1,4-dihydropyridines offer numerous advantages. The various sections cover tissue specificity of channel labeling, the complex interactions of divalent cations with the (/sup 3/H)nimodipine-labeled calcium channels, and the allosteric regulation of (/sup 3/H)nimodipine binding by the optically pure enantiomers of phenylalkylamine and benzothiazepine calcium channel blockers. A comparison of the properties of different tritiated 1,4-dihydropyridine radioligands and the iodinated channel probe (/sup 125/I)iodipine is given.

  19. Solar Imagery - Chromosphere - Calcium

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset consists of full-disk images of the sun in Calcium (Ca) II K wavelength (393.4 nm). Ca II K imagery reveal magnetic structures of the sun from about 500...

  20. Delayed crosslinker composition

    Energy Technology Data Exchange (ETDEWEB)

    Hodge, R.M.

    1989-01-10

    A crosslinker composition is described that can produce delayed crosslinking of an aqueous solution of a crosslinkable organic polymer. It consists of about 1% to about 10% by weight of an organic zirconium complex and about 2% to about 37% by weight organic hydroxycarboxylic acid selected from the group consisting of lactic, mandelic and hydroxyacetic acids the pH of the composition being no greater than 4.8.

  1. Delayed visual maturation.

    OpenAIRE

    Cole, G F; Hungerford, J.; Jones, R B

    1984-01-01

    Sixteen blind babies who were considered to be showing the characteristics of delayed visual maturation were studied prospectively. The diagnosis was made on clinical grounds, and the criteria for this are discussed. All of these infants developed visual responses between 4 and 6 months of age and had normal or near normal visual acuities by 1 year of age. Long term follow up, however, has shown neurological abnormalities in some of these children.

  2. Delayed visual maturation.

    Science.gov (United States)

    Fielder, A R; Russell-Eggitt, I R; Dodd, K L; Mellor, D H

    1985-01-01

    Fifty-three infants with delayed visual maturation (DVM) are presented. These have been classified according to their ocular and systemic features into three groups: DVM as an isolated anomaly, in association with mental retardation, and ocular abnormalities accompanied by DVM. The clinical features are discussed, particularly regarding the time and speed of visual improvement in the three groups. Infants with DVM who experienced difficulties in the perinatal period have an increased risk of developing permanent neurological sequelae.

  3. Delayed breast implant reconstruction

    DEFF Research Database (Denmark)

    Hvilsom, Gitte B.; Hölmich, Lisbet R.; Steding-Jessen, Marianne

    2011-01-01

    Studies of complications following reconstructive surgery with implants among women with breast cancer are needed. As the, to our knowledge, first prospective long-term study we evaluated the occurrence of complications following delayed breast reconstruction separately for one- and two-stage pro......Studies of complications following reconstructive surgery with implants among women with breast cancer are needed. As the, to our knowledge, first prospective long-term study we evaluated the occurrence of complications following delayed breast reconstruction separately for one- and two......-stage procedures. From the Danish Registry for Plastic Surgery of the Breast, which has prospectively registered data for women undergoing breast implantations since 1999, we identified 559 women without a history of radiation therapy undergoing 592 delayed breast reconstructions following breast cancer during...... the period 1999 to 2006; 239 one-stage procedures and 353 two-stage procedures. The postoperative course through November 2009 was evaluated by cumulative incidence adjusting for competing risks for the selected outcomes; hematoma, infection, seroma, implant rupture, severe capsular contracture (modified...

  4. Delay in atomic photoionization

    CERN Document Server

    Kheifets, A S

    2010-01-01

    We analyze the time delay between emission of photoelectrons from the outer valence $ns$ and $np$ sub-shells in noble gas atoms following absorption of an attosecond XUV pulse. By solving the time dependent Schr\\"odinger equation and carefully examining the time evolution of the photoelectron wave packet, we establish the apparent "time zero" when the photoelectron leaves the atom. Various processes such as elastic scattering of the photoelectron on the parent ion and many-electron correlation affect the quantum phase of the dipole transition matrix element, the energy dependence of which defines the emission timing. This qualitatively explains the time delay between photoemission from the $2s$ and $2p$ sub-shells of Ne as determined experimentally by attosecond streaking [{\\em Science} {\\bf 328}, 1658 (2010)]. However, with our extensive numerical modeling, we were only able to account for less than a half of the measured time delay of $21\\pm5$~as. We argue that the XUV pulse alone cannot produce such a larg...

  5. Time-Delay Interferometry

    Directory of Open Access Journals (Sweden)

    Massimo Tinto

    2014-08-01

    Full Text Available Equal-arm detectors of gravitational radiation allow phase measurements many orders of magnitude below the intrinsic phase stability of the laser injecting light into their arms. This is because the noise in the laser light is common to both arms, experiencing exactly the same delay, and thus cancels when it is differenced at the photo detector. In this situation, much lower level secondary noises then set the overall performance. If, however, the two arms have different lengths (as will necessarily be the case with space-borne interferometers, the laser noise experiences different delays in the two arms and will hence not directly cancel at the detector. In order to solve this problem, a technique involving heterodyne interferometry with unequal arm lengths and independent phase-difference readouts has been proposed. It relies on properly time-shifting and linearly combining independent Doppler measurements, and for this reason it has been called time-delay interferometry (TDI. This article provides an overview of the theory, mathematical foundations, and experimental aspects associated with the implementation of TDI. Although emphasis on the application of TDI to the Laser Interferometer Space Antenna (LISA mission appears throughout this article, TDI can be incorporated into the design of any future space-based mission aiming to search for gravitational waves via interferometric measurements. We have purposely left out all theoretical aspects that data analysts will need to account for when analyzing the TDI data combinations.

  6. The Plasma Membrane Calcium Pump

    Science.gov (United States)

    Rasmussen, H.

    1983-01-01

    Three aspect of cellular calcium metabolism in animal cells was discussed including the importance of the plasma membrane in calcium homeostasis, experiments dealing with the actual mechanism of the calcium pump, and the function of the pump in relationship to the mitochondria and to the function of calmodulin in the intact cell.

  7. Calcium addition in straw gasification

    DEFF Research Database (Denmark)

    Risnes, H.; Fjellerup, Jan Søren; Henriksen, Ulrik Birk

    2003-01-01

    The present work focuses on the influence of calcium addition in gasification. The inorganic¿organic element interaction as well as the detailed inorganic¿inorganic elements interaction has been studied. The effect of calcium addition as calcium sugar/molasses solutions to straw significantly...

  8. Impregnating Coal With Calcium Carbonate

    Science.gov (United States)

    Sharma, Pramod K.; Voecks, Gerald E.; Gavalas, George R.

    1991-01-01

    Relatively inexpensive process proposed for impregnating coal with calcium carbonate to increase rates of gasification and combustion of coal and to reduce emission of sulfur by trapping sulfur in calcium sulfide. Process involves aqueous-phase reactions between carbon dioxide (contained within pore network of coal) and calcium acetate. Coal impregnated with CO2 by exposing it to CO2 at high pressure.

  9. Transient Features in Nanosecond Pulsed Electric Fields Differentially Modulate Mitochondria and Viability

    Science.gov (United States)

    Beebe, Stephen J.; Chen, Yeong-Jer; Sain, Nova M.; Schoenbach, Karl H.; Xiao, Shu

    2012-01-01

    It is hypothesized that high frequency components of nanosecond pulsed electric fields (nsPEFs), determined by transient pulse features, are important for maximizing electric field interactions with intracellular structures. For monopolar square wave pulses, these transient features are determined by the rapid rise and fall of the pulsed electric fields. To determine effects on mitochondria membranes and plasma membranes, N1-S1 hepatocellular carcinoma cells were exposed to single 600 ns pulses with varying electric fields (0–80 kV/cm) and short (15 ns) or long (150 ns) rise and fall times. Plasma membrane effects were evaluated using Fluo-4 to determine calcium influx, the only measurable source of increases in intracellular calcium. Mitochondria membrane effects were evaluated using tetramethylrhodamine ethyl ester (TMRE) to determine mitochondria membrane potentials (ΔΨm). Single pulses with short rise and fall times caused electric field-dependent increases in calcium influx, dissipation of ΔΨm and cell death. Pulses with long rise and fall times exhibited electric field-dependent increases in calcium influx, but diminished effects on dissipation of ΔΨm and viability. Results indicate that high frequency components have significant differential impact on mitochondria membranes, which determines cell death, but lesser variances on plasma membranes, which allows calcium influxes, a primary determinant for dissipation of ΔΨm and cell death. PMID:23284682

  10. Transient features in nanosecond pulsed electric fields differentially modulate mitochondria and viability.

    Directory of Open Access Journals (Sweden)

    Stephen J Beebe

    Full Text Available It is hypothesized that high frequency components of nanosecond pulsed electric fields (nsPEFs, determined by transient pulse features, are important for maximizing electric field interactions with intracellular structures. For monopolar square wave pulses, these transient features are determined by the rapid rise and fall of the pulsed electric fields. To determine effects on mitochondria membranes and plasma membranes, N1-S1 hepatocellular carcinoma cells were exposed to single 600 ns pulses with varying electric fields (0-80 kV/cm and short (15 ns or long (150 ns rise and fall times. Plasma membrane effects were evaluated using Fluo-4 to determine calcium influx, the only measurable source of increases in intracellular calcium. Mitochondria membrane effects were evaluated using tetramethylrhodamine ethyl ester (TMRE to determine mitochondria membrane potentials (ΔΨm. Single pulses with short rise and fall times caused electric field-dependent increases in calcium influx, dissipation of ΔΨm and cell death. Pulses with long rise and fall times exhibited electric field-dependent increases in calcium influx, but diminished effects on dissipation of ΔΨm and viability. Results indicate that high frequency components have significant differential impact on mitochondria membranes, which determines cell death, but lesser variances on plasma membranes, which allows calcium influxes, a primary determinant for dissipation of ΔΨm and cell death.

  11. Recent development of transient electronics

    Directory of Open Access Journals (Sweden)

    Huanyu Cheng

    2016-01-01

    Full Text Available Transient electronics are an emerging class of electronics with the unique characteristic to completely dissolve within a programmed period of time. Since no harmful byproducts are released, these electronics can be used in the human body as a diagnostic tool, for instance, or they can be used as environmentally friendly alternatives to existing electronics which disintegrate when exposed to water. Thus, the most crucial aspect of transient electronics is their ability to disintegrate in a practical manner and a review of the literature on this topic is essential for understanding the current capabilities of transient electronics and areas of future research. In the past, only partial dissolution of transient electronics was possible, however, total dissolution has been achieved with a recent discovery that silicon nanomembrane undergoes hydrolysis. The use of single- and multi-layered structures has also been explored as a way to extend the lifetime of the electronics. Analytical models have been developed to study the dissolution of various functional materials as well as the devices constructed from this set of functional materials and these models prove to be useful in the design of the transient electronics.

  12. Current Vaccine Shortages and Delays

    Science.gov (United States)

    ... value="Submit" /> Related Links Vaccines & Immunizations Current Vaccine Shortages & Delays Recommend on Facebook Tweet Share Compartir ... vaccination are included in this update. Chart of Vaccines* in Delay or Shortage National Vaccine Supply Shortages ...

  13. Size of Shell Universe in Light of FERMI GBM Transient Associated with GW150914

    CERN Document Server

    Gogberashvili, Merab; Sarkisyan-Grinbaum, Edward

    2016-01-01

    We apply the delay in timing of FERMI GMB transient occurred in coincidence with gravitational waves event GW150914 observed by LIGO to constrain the size of the spherical brane-universe expanding in multi-dimensional space-time. A bound on spatial curvature of the brane is obtained.

  14. Peri-ischemic aminoguanidine fails to ameliorate neurologic and histopathologic outcome after transient spinal cord ischemia

    NARCIS (Netherlands)

    Lips, Jeroen; de Jager, Steven W.; de Haan, Peter; Bakker, O.; Vanicky, I.; Jacobs, Michael J.; Kalkman, Cor J.

    2002-01-01

    Inhibition of neurotoxic events that lead to delayed cellular damage may prevent motor function loss after transient spinal cord ischemia. An important effect of the neuroprotective substance aminoguanidine (AG) is the inhibition of inducible nitric oxide synthase (iNOS), a perpetrator of focal

  15. PKA controls calcium influx into motor neurons during a rhythmic behavior.

    Directory of Open Access Journals (Sweden)

    Han Wang

    Full Text Available Cyclic adenosine monophosphate (cAMP has been implicated in the execution of diverse rhythmic behaviors, but how cAMP functions in neurons to generate behavioral outputs remains unclear. During the defecation motor program in C. elegans, a peptide released from the pacemaker (the intestine rhythmically excites the GABAergic neurons that control enteric muscle contractions by activating a G protein-coupled receptor (GPCR signaling pathway that is dependent on cAMP. Here, we show that the C. elegans PKA catalytic subunit, KIN-1, is the sole cAMP target in this pathway and that PKA is essential for enteric muscle contractions. Genetic analysis using cell-specific expression of dominant negative or constitutively active PKA transgenes reveals that knockdown of PKA activity in the GABAergic neurons blocks enteric muscle contractions, whereas constitutive PKA activation restores enteric muscle contractions to mutants defective in the peptidergic signaling pathway. Using real-time, in vivo calcium imaging, we find that PKA activity in the GABAergic neurons is essential for the generation of synaptic calcium transients that drive GABA release. In addition, constitutively active PKA increases the duration of calcium transients and causes ectopic calcium transients that can trigger out-of-phase enteric muscle contractions. Finally, we show that the voltage-gated calcium channels UNC-2 and EGL-19, but not CCA-1 function downstream of PKA to promote enteric muscle contractions and rhythmic calcium influx in the GABAergic neurons. Thus, our results suggest that PKA activates neurons during a rhythmic behavior by promoting presynaptic calcium influx through specific voltage-gated calcium channels.

  16. Obscure Severe Infrarenal Aortoiliac Stenosis With Severe Transient Lactic Acidosis

    Directory of Open Access Journals (Sweden)

    Teerapat Nantsupawat MD

    2013-01-01

    Full Text Available A 57-year-old man presented with sudden onset of leg pain, right-sided weakness, aphasia, confusion, drooling, and severe lactic acidosis (15 mmol/L. He had normal peripheral pulses and demonstrated no pain, pallor, poikilothermia, paresthesia, or paralysis. Empiric antibiotics, aspirin, full-dose enoxaparin, and intravenous fluid were initiated. Lactic acid level decreased to 2.5 mmol/L. The patient was subsequently extubated and was alert and oriented with no complaints of leg or abdominal pain. Unexpectedly, the patient developed cardiac arrest, rebound severe lactic acidosis (8.13 mmol/L, and signs of acute limb ischemia. Emergent computed tomography of the aorta confirmed infrarenal aortoiliac thrombosis. Transient leg pain and transient severe lactic acidosis can be unusual presentations of severe infrarenal aortoiliac stenosis. When in doubt, vascular studies should be implemented without delay to identify this catastrophic diagnosis.

  17. Transient Newton rings in dielectrics upon fs laser ablation

    CERN Document Server

    Garcia-Lechuga, Mario; Hernandez-Rueda, Javier; Solis, Javier

    2014-01-01

    We report the appearance of transient Newton rings in dielectrics (sapphire and lead-oxide glass) during ablation with single fs laser pulses. Employing femtosecond microscopy with 800 nm excitation and 400 nm illumination, we observe a characteristic ring pattern that dynamically changes for increasing delay times between pump and probe pulse. Such transient Newton rings have been previously observed in metals and semiconductors at fluences above the ablation threshold and were related to optical interference of the probe beam reflected at the front surface of the ablating layer and at the interface of the non-ablating substrate. Yet, it had been generally assumed that this phenomenon cannot be (and has not been) observed in dielectrics due to the different ablation mechanism and optical properties of dielectrics. The fact that we are able to observe them has important consequences for the comprehension of the ablation mechanisms in dielectrics and provides a new method for investigating these mechanisms in ...

  18. The calcium-sensing receptor promotes urinary acidification to prevent nephrolithiasis.

    NARCIS (Netherlands)

    Renkema, K.Y.; Velic, A.; Dijkman, H.B.; Verkaart, S.A.J.; Kemp, J.W.C.M. van der; Nowik, M.; Timmermans, K.; Doucet, A.; Wagner, C.A.; Bindels, R.J.M.; Hoenderop, J.G.J.

    2009-01-01

    Hypercalciuria increases the risk for urolithiasis, but renal adaptive mechanisms reduce this risk. For example, transient receptor potential vanilloid 5 knockout (TPRV5(-/-)) mice lack kidney stones despite urinary calcium (Ca(2+)) wasting and hyperphosphaturia, perhaps as a result of their

  19. The TRPV5/6 calcium channels contain multiple calmodulin binding sites with differential binding properties.

    NARCIS (Netherlands)

    Kovalevskaya, N.V.; Bokhovchuk, F.M.; Vuister, G.W.

    2012-01-01

    The epithelial Ca(2+) channels TRPV5/6 (transient receptor potential vanilloid 5/6) are thoroughly regulated in order to fine-tune the amount of Ca(2+) reabsorption. Calmodulin has been shown to be involved into calcium-dependent inactivation of TRPV5/6 channels by binding directly to the distal

  20. Calcium signaling in taste cells.

    Science.gov (United States)

    Medler, Kathryn F

    2015-09-01

    The sense of taste is a common ability shared by all organisms and is used to detect nutrients as well as potentially harmful compounds. Thus taste is critical to survival. Despite its importance, surprisingly little is known about the mechanisms generating and regulating responses to taste stimuli. All taste responses depend on calcium signals to generate appropriate responses which are relayed to the brain. Some taste cells have conventional synapses and rely on calcium influx through voltage-gated calcium channels. Other taste cells lack these synapses and depend on calcium release to formulate an output signal through a hemichannel. Beyond establishing these characteristics, few studies have focused on understanding how these calcium signals are formed. We identified multiple calcium clearance mechanisms that regulate calcium levels in taste cells as well as a calcium influx that contributes to maintaining appropriate calcium homeostasis in these cells. Multiple factors regulate the evoked taste signals with varying roles in different cell populations. Clearly, calcium signaling is a dynamic process in taste cells and is more complex than has previously been appreciated. This article is part of a Special Issue entitled: 13th European Symposium on Calcium. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Activation of transient receptor potential ankyrin 1 by eugenol.

    Science.gov (United States)

    Chung, G; Im, S T; Kim, Y H; Jung, S J; Rhyu, M-R; Oh, S B

    2014-03-07

    Eugenol is a bioactive plant extract used as an analgesic agent in dentistry. The structural similarity of eugenol to cinnamaldehyde, an active ligand for transient receptor potential ankyrin 1 (TRPA1), suggests that eugenol might produce its effect via TRPA1, in addition to TRPV1 as we reported previously. In this study, we investigated the effect of eugenol on TRPA1, by fura-2-based calcium imaging and patch clamp recording in trigeminal ganglion neurons and in a heterologous expression system. As the result, eugenol induced robust calcium responses in rat trigeminal ganglion neurons that responded to a specific TRPA1 agonist, allyl isothiocyanate (AITC), and not to capsaicin. Capsazepine, a TRPV1 antagonist failed to inhibit eugenol-induced calcium responses in AITC-responding neurons. In addition, eugenol response was observed in trigeminal ganglion neurons from TRPV1 knockout mice and human embryonic kidney 293 cell lines that express human TRPA1, which was inhibited by TRPA1-specific antagonist HC-030031. Eugenol-evoked TRPA1 single channel activity and eugenol-induced TRPA1 currents were dose-dependent with EC50 of 261.5μM. In summary, these results demonstrate that the activation of TRPA1 might account for another molecular mechanism underlying the pharmacological action of eugenol. Copyright © 2013 IBRO. Published by Elsevier Ltd. All rights reserved.

  2. Explosive and Radio-Selected Transients: Transient Astronomy with ...

    Indian Academy of Sciences (India)

    In India, active research is going on in transient astronomy, especially in the fields of supernovae, gamma ray .... to ∼9 as of now. We currently understand them as catastrophic events generating a central engine which ..... bubbles blown by hot progenitor or with complex circumstellar environments set up by variable winds.

  3. Explosive and Radio-Selected Transients: Transient Astronomy with ...

    Indian Academy of Sciences (India)

    Therefore, multiwaveband observational efforts with wide fields of view will be the key to progress of transients astronomy from the middle 2020s offering unprecedented deep images and high spatial and spectral resolutions. Radio observations of Gamma Ray Bursts (GRBs) with SKA will uncover not only much fainter ...

  4. Delay Choice vs. Delay Maintenance: Different Measures of Delayed Gratification in Capuchin Monkeys (Cebus apella)

    Science.gov (United States)

    Addessi, Elsa; Paglieri, Fabio; Beran, Michael J.; Evans, Theodore A.; Macchitella, Luigi; De Petrillo, Francesca; Focaroli, Valentina

    2013-01-01

    Delaying gratification involves two components: (i) delay choice (selecting a delayed reward over an immediate one), and (ii) delay maintenance (sustaining the decision to delay gratification even if the immediate reward is available during the delay). In primates, two tasks most commonly have explored these components, the Intertemporal choice task and the Accumulation task. It is unclear whether these tasks provide equivalent measures of delay of gratification. Here, we compared the performance of the same capuchin monkeys, belonging to two study populations, between these tasks. We found only limited evidence of a significant correlation in performance. Consequently, in contrast to what is often assumed, our data provide only partial support to the hypothesis that these tasks provide equivalent measures of delay of gratification. PMID:23544770

  5. Delay choice versus delay maintenance: different measures of delayed gratification in capuchin monkeys (Cebus apella).

    Science.gov (United States)

    Addessi, Elsa; Paglieri, Fabio; Beran, Michael J; Evans, Theodore A; Macchitella, Luigi; De Petrillo, Francesca; Focaroli, Valentina

    2013-11-01

    Delaying gratification involves 2 components: (1) delay choice (selecting a delayed reward over an immediate one) and (2) delay maintenance (sustaining the decision to delay gratification even if the immediate reward is available during the delay). Two tasks most commonly have explored these components in primates: the intertemporal choice task and the accumulation task. It is unclear whether these tasks provide equivalent measures of delay of gratification. Here, we compared the performance on the intertemporal choice task and the accumulation task of capuchin monkeys (Cebus apella) belonging to 2 study populations. We found only limited evidence of a significant correlation in performance. Consequently, in contrast to what is often assumed, our data provide only partial support for the hypothesis that these tasks provide equivalent measures of delay of gratification.

  6. Delaying information search

    Directory of Open Access Journals (Sweden)

    Yaniv Shani

    2012-11-01

    Full Text Available In three studies, we examined factors that may temporarily attenuate information search. People are generally curious and dislike uncertainty, which typically encourages them to look for relevant information. Despite these strong forces that promote information search, people sometimes deliberately delay obtaining valuable information. We find they may do so when they are concerned that the information might interfere with future pleasurable activities. Interestingly, the decision to search or to postpone searching for information is influenced not only by the value and importance of the information itself but also by well-being maintenance goals related to possible detrimental effects that negative knowledge may have on unrelated future plans.

  7. Calcium dynamics predict direction of synaptic plasticity in striatal spiny projection neurons.

    Science.gov (United States)

    Jędrzejewska-Szmek, Joanna; Damodaran, Sriraman; Dorman, Daniel B; Blackwell, Kim T

    2017-04-01

    The striatum is a major site of learning and memory formation for sensorimotor and cognitive association. One of the mechanisms used by the brain for memory storage is synaptic plasticity - the long-lasting, activity-dependent change in synaptic strength. All forms of synaptic plasticity require an elevation in intracellular calcium, and a common hypothesis is that the amplitude and duration of calcium transients can determine the direction of synaptic plasticity. The utility of this hypothesis in the striatum is unclear in part because dopamine is required for striatal plasticity and in part because of the diversity in stimulation protocols. To test whether calcium can predict plasticity direction, we developed a calcium-based plasticity rule using a spiny projection neuron model with sophisticated calcium dynamics including calcium diffusion, buffering and pump extrusion. We utilized three spike timing-dependent plasticity (STDP) induction protocols, in which postsynaptic potentials are paired with precisely timed action potentials and the timing of such pairing determines whether potentiation or depression will occur. Results show that despite the variation in calcium dynamics, a single, calcium-based plasticity rule, which explicitly considers duration of calcium elevations, can explain the direction of synaptic weight change for all three STDP protocols. Additional simulations show that the plasticity rule correctly predicts the NMDA receptor dependence of long-term potentiation and the L-type channel dependence of long-term depression. By utilizing realistic calcium dynamics, the model reveals mechanisms controlling synaptic plasticity direction, and shows that the dynamics of calcium, not just calcium amplitude, are crucial for synaptic plasticity. © 2016 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  8. DISTILLATION OF CALCIUM

    Science.gov (United States)

    Barton, J.

    1954-07-27

    This invention relates to an improvement in the process for the purification of caicium or magnesium containing an alkali metal as impurity, which comprises distiiling a batch of the mixture in two stages, the first stage distillation being carried out in the presence of an inert gas at an absolute pressure substantially greater than the vapor pressure of calcium or maguesium at the temperature of distillation, but less than the vaper pressure at that temperature of the alkali metal impurity so that only the alkali metal is vaporized and condensed on a condensing surface. A second stage distilso that substantially only the calcium or magnesium distills under its own vapor pressure only and condenses in solid form on a lower condensing surface.

  9. The role of grain boundaries and transient porosity in rocks as fluid pathways for reaction front propagation

    NARCIS (Netherlands)

    Jonas, Laura; John, Timm; King, Helen E.; Geisler, Thorsten; Putnis, Andrew

    2014-01-01

    The pseudomorphic replacement of Carrara marble by calcium phosphates was used as a model system in order to study the influence of different fluid pathways for reaction front propagation induced by fluid-rock interaction. In this model, grain boundaries present in the rock as well as the transient

  10. Origin of delayed outward ionic current in charge movement traces from frog skeletal muscle.

    Science.gov (United States)

    Hui, C S; Chen, W

    1994-08-15

    1. Non-linear membrane ionic current was studied in highly stretched cut frog twitch fibres in a double Vaseline-gap voltage clamp chamber, with the internal solution containing 0.1 mM EGTA and the external solution containing Cl- as the major anion. After the Na+ currents was abolished by TTX in the external solution and the K+ currents were suppressed by external TEA+ and Rb+ and internal Cs+, a delayed outward ionic current with a time course similar to that of the delayed rectifier current was observed during depolarization. 2. The delayed outward ionic current was resistant to 1 mM 3,4-diaminopyridine (3,4-DAP) in the external solution and was unaltered when a fraction of the internal Cs+ was replaced by K+ or Na+, suggesting that the current was not carried by cations flowing through the delayed rectifiers. 3. The delayed outward ionic current was greatly reduced by replacing the external Cl- with CH3SO3-,SO4(2-), glutamate or gluconate, indicating strongly that the current was carried by Cl- flowing through anion channels. The current was also suppressed by 1 mM external 9-anthracenecarboxylic acid (9-ACA). 4. The delayed outward ionic current was reduced by blockers of calcium-dependent Cl- channels, such as SITS and frusemide (furosemide), in a dose- and voltage-dependent manner and by increasing intracellular [EGTA] to 20 mM, suggesting that part of the Cl- current in the muscle fibres could be calcium dependent. 5. The total Cl- current could be dissected into calcium-dependent and calcium-independent components. Each component accounted for roughly half of the total Cl- current. The maximum slope conductance of the calcium-dependent Cl- channels was 60.9 +/- 6.0 microS microF-1 (mean +/- S.E.M., n = 4).

  11. The Effect of a Novel Highly Selective Inhibitor of the Sodium/Calcium Exchanger (NCX) on Cardiac Arrhythmias in In Vitro and In Vivo Experiments.

    Science.gov (United States)

    Kohajda, Zsófia; Farkas-Morvay, Nikolett; Jost, Norbert; Nagy, Norbert; Geramipour, Amir; Horváth, András; Varga, Richárd S; Hornyik, Tibor; Corici, Claudia; Acsai, Károly; Horváth, Balázs; Prorok, János; Ördög, Balázs; Déri, Szilvia; Tóth, Dániel; Levijoki, Jouko; Pollesello, Piero; Koskelainen, Tuula; Otsomaa, Leena; Tóth, András; Baczkó, István; Leprán, István; Nánási, Péter P; Papp, Julius Gy; Varró, András; Virág, László

    2016-01-01

    In this study the effects of a new, highly selective sodium-calcium exchanger (NCX) inhibitor, ORM-10962 were investigated on cardiac NCX current, Ca2+ transients, cell shortening and in experimental arrhythmias. The level of selectivity of the novel inhibitor on several major transmembrane ion currents (L-type Ca2+ current, major repolarizing K+ currents, late Na+ current, Na+/K+ pump current) was also determined. Ion currents in single dog ventricular cells (cardiac myocytes; CM), and action potentials in dog cardiac multicellular preparations were recorded utilizing the whole-cell patch clamp and standard microelectrode techniques, respectively. Ca2+ transients and cell shortening were measured in fluorescent dye loaded isolated dog myocytes. Antiarrhythmic effects of ORM-10962 were studied in anesthetized ouabain (10 μg/kg/min i.v.) pretreated guinea pigs and in ischemia-reperfusion models (I/R) of anesthetized coronary artery occluded rats and Langendorff perfused guinea pigs hearts. ORM-10962 significantly reduced the inward/outward NCX currents with estimated EC50 values of 55/67 nM, respectively. The compound, even at a high concentration of 1 μM, did not modify significantly the magnitude of ICaL in CMs, neither had any apparent influence on the inward rectifier, transient outward, the rapid and slow components of the delayed rectifier potassium currents, the late and peak sodium and Na+/K+ pump currents. NCX inhibition exerted moderate positive inotropic effect under normal condition, negative inotropy when reverse, and further positive inotropic effect when forward mode was facilitated. In dog Purkinje fibres 1 μM ORM-10962 decreased the amplitude of digoxin induced delayed afterdepolarizations (DADs). Pre-treatment with 0.3 mg/kg ORM-10962 (i.v.) 10 min before starting ouabain infusion significantly delayed the development and recurrence of ventricular extrasystoles (by about 50%) or ventricular tachycardia (by about 30%) in anesthetized guinea pigs

  12. Calcium metabolism and cardiovascular function after spaceflight

    Science.gov (United States)

    Hatton, Daniel C.; Yue, Qi; Dierickx, Jacqueline; Roullet, Chantal; Otsuka, Keiichi; Watanabe, Mitsuaki; Coste, Sarah; Roullet, Jean Baptiste; Phanouvang, Thongchan; Orwoll, Eric; hide

    2002-01-01

    To determine the influence of dietary calcium on spaceflight-induced alterations in calcium metabolism and blood pressure (BP), 9-wk-old spontaneously hypertensive rats, fed either high- (2%) or low-calcium (0.02%) diets, were flown on an 18-day shuttle flight. On landing, flight animals had increased ionized calcium (P platelet free calcium (intracellular calcium concentration) were also reduced (P metabolism (P metabolism are relatively impervious to dietary calcium in the short term, 2) increased ionized calcium did not normalize low-calcium-induced elevations of BP, and 3) parathyroid hormone was paradoxically increased in the high-calcium-fed flight animals after landing.

  13. Compensation of transient beam-loading in Clic main Linac

    CERN Document Server

    Kononenko, O; Grudiev, A

    2010-01-01

    Compensating transient beam loading to maintain a 0.03% rms relative beam energy spread is a key issue for the CLIC two-beam acceleration technique. The combination of short pulses, narrow bandwidth rf components and the limited number of rf pulse shaping “knobs” given by the drive beam generation scheme makes meeting this specification challenging. A dedicated model, which takes into account all stages of drive beam generation, including the delay loop and combiner rings, the single-bunch response of the power generation structure (PETS), the RF waveguide network transfer function and dispersive properties of the accelerating structure has been developed. The drive beam phase switching delays, resulting rf pulse shape, and finally the energy spread are presented.

  14. Dark adaptation during transient hyperglycemia in type 2 diabetes

    DEFF Research Database (Denmark)

    Holfort, Stig Kraglund; Jackson, Gregory R; Larsen, Michael

    2010-01-01

    It was the purpose of the present study to examine dark adaptation in subjects with type 2 diabetes during transient hyperglycemia. Twenty-four subjects with type 2 diabetes and minimal diabetic retinopathy were randomized to undergo an oral glucose tolerance test (OGTT) or to remain fasting. Dark...... glycemia increased in the 12 OGTT subjects, from 8.6±2.1 at baseline to 21.1±3.6 mM after 80 min. In the OGTT group, four out of seven subjects with delayed dark adaptation at baseline reached normal values during hyperglycemia. All examined aspects of rod adaptation were accelerated by hyperglycemia (time...... to rod-cone break -26%; time to rod intercept -16%, rod sensitivity recovery slope (log units/min) +35%), whereas no measurable change in cone adaptation was seen. The results are consistent with rod adaptation being limited by glycemia and with rod adaptation being delayed in subjects with diabetes...

  15. Models of calcium signalling

    CERN Document Server

    Dupont, Geneviève; Kirk, Vivien; Sneyd, James

    2016-01-01

    This book discusses the ways in which mathematical, computational, and modelling methods can be used to help understand the dynamics of intracellular calcium. The concentration of free intracellular calcium is vital for controlling a wide range of cellular processes, and is thus of great physiological importance. However, because of the complex ways in which the calcium concentration varies, it is also of great mathematical interest.This book presents the general modelling theory as well as a large number of specific case examples, to show how mathematical modelling can interact with experimental approaches, in an interdisciplinary and multifaceted approach to the study of an important physiological control mechanism. Geneviève Dupont is FNRS Research Director at the Unit of Theoretical Chronobiology of the Université Libre de Bruxelles;Martin Falcke is head of the Mathematical Cell Physiology group at the Max Delbrück Center for Molecular Medicine, Berlin;Vivien Kirk is an Associate Professor in the Depar...

  16. Epidemiology of delayed ejaculation

    Science.gov (United States)

    Di Sante, Stefania; Mollaioli, Daniele; Gravina, Giovanni Luca; Ciocca, Giacomo; Limoncin, Erika; Carosa, Eleonora; Lenzi, Andrea

    2016-01-01

    A large body of literature on diminished ejaculatory disorders has been generated without the use of a clear diagnostic definition. Many studies have not distinguished between the orgasm and ejaculation disorders leading to doubtful results. Delayed ejaculation (DE) is one of the diminished ejaculatory disorders, which range from varying delays in ejaculatory latency to a complete inability to ejaculate. The present review is aimed at providing a comprehensive overview of the current knowledge on the definition and epidemiology of diminished ejaculatory disorders. We focus on the acquired diseases, such as benign prostatic hyperplasia (BPH) and specific drug regimens that may cause an iatrogenic form of ejaculatory disorder. In addition, the impact of aging is discussed since the prevalence of DE appears to be moderately but positively related to age. Finally, we also focus on the importance of the hormonal milieu on male ejaculation. To date, evidence on the endocrine control of ejaculation is derived from small clinical trials, but the evidence suggests that hormones modulate the ejaculatory process by altering its overall latency. PMID:27652226

  17. Epidemiology of delayed ejaculation.

    Science.gov (United States)

    Di Sante, Stefania; Mollaioli, Daniele; Gravina, Giovanni Luca; Ciocca, Giacomo; Limoncin, Erika; Carosa, Eleonora; Lenzi, Andrea; Jannini, Emmanuele A

    2016-08-01

    A large body of literature on diminished ejaculatory disorders has been generated without the use of a clear diagnostic definition. Many studies have not distinguished between the orgasm and ejaculation disorders leading to doubtful results. Delayed ejaculation (DE) is one of the diminished ejaculatory disorders, which range from varying delays in ejaculatory latency to a complete inability to ejaculate. The present review is aimed at providing a comprehensive overview of the current knowledge on the definition and epidemiology of diminished ejaculatory disorders. We focus on the acquired diseases, such as benign prostatic hyperplasia (BPH) and specific drug regimens that may cause an iatrogenic form of ejaculatory disorder. In addition, the impact of aging is discussed since the prevalence of DE appears to be moderately but positively related to age. Finally, we also focus on the importance of the hormonal milieu on male ejaculation. To date, evidence on the endocrine control of ejaculation is derived from small clinical trials, but the evidence suggests that hormones modulate the ejaculatory process by altering its overall latency.

  18. Delayed Choice Quantum Cryptography

    Science.gov (United States)

    Jeffrey, Evan; Kwiat, Paul

    2002-05-01

    Quantum Cryptography has recently gained attention as a method of communication with security guaranteed by the laws of physics. In particular, according to quantum mechanics, any measurement of an unknown quantum state perturbs the state in an easily detectable manner. One practical difficulty in implementing quantum cryptography is that Alice must encode each bit in a random basis, and Bob must choose the correct basis to get a shared bit of the final key. This necessarily introduces at least a 50% loss of data rate, and higher in protocols that use more than two bases in order to be more sensitive to eavesdroppers. We show that Bob can solve this by storing his photon until Alice has send the basis to use, allowing him to measure in the correct basis 100% of the time, while preventing Eve from having that information in time to use it maliciously. Bob accomplishes this storage by means of an optical delay line -- a pair of mirrors arranged so that his photon makes many round trips through the cavity before emerging and entering the detector. By using mirrors with a slight astigmatism, hope to achieve hundreds of round trips and a few microseconds of delay time.

  19. Pseudotumoral delayed cerebral radionecrosis

    Energy Technology Data Exchange (ETDEWEB)

    Ciaudo-Lacroix, C.; Lapresle, J. (Centre Hospitalier de Bicetre, 94 - Le Kremlin-Bicetre (France))

    1985-01-01

    A 60 year-old woman with a scalp epithelioma underwent radiotherapy, the dose being 57 Gray. A first epileptic seizure occurred twenty months later. Neurological examination revealed signs of left hemisphere involvement. ..gamma..EG, angiography, CT scans, demonstrated a pseudotumoral avascular process. On account of the localisation, the patient being right-handed, no surgical procedure was performed. In spite of corticotherapy and anticonvulsive treatment, seizures recurred and neurological signs slowly progressed. The patient died, 22 months after the first seizure, of an associated disseminated carcinoma with cachexia. Neuropathological examination showed a massive lesion presenting all the features of delayed radionecrosis in the left hemisphere: situated mainly in the white matter; numerous vascular abnormalities; wide-spread demyelination; disappearance of oligoglial cells. The Authors recall the clinical and anatomical aspects of this condition for which the only successful treatment is surgical removal when location and size of the lesion permit. Finally, the mechanisms which have been proposed to explain this delayed cerebral radionecrosis are discussed.

  20. Cutaneous Penetration-Enhancing Effect of Menthol: Calcium Involvement.

    Science.gov (United States)

    Joshi, Amit; Joshi, Abhay; Patel, Hiren; Ponnoth, Dovenia; Stagni, Grazia

    2017-07-01

    Menthol is a naturally occurring terpene used as a penetration enhancer in topical and transdermal formulations. Literature shows a growing interest in menthol's interactions with the transient receptor potential melastatin 8. A decrease in extracellular Ca 2+ due to the activation of the transient receptor potential melastatin 8 receptor produces inhibition of E-cadherin expression that is responsible for cell-cell adhesion. Because calcium is present in the entire epidermis, the purpose of this study is to evaluate whether the aforementioned properties of menthol are also related to its penetration-enhancing effects. We formulated 16 gels: (i) drug-alone (diphenhydramine or lidocaine), (ii) drug with menthol, (iii) drug, menthol, and calcium channel blocker (CCB; verapamil or diltiazem), and (iv) drug and CCB. In vitro studies showed no effect of the CCB on the release of the drugs either with or without menthol. In vivo experiments were performed for each drug/menthol/CCB combination gel by applying 4 formulations on a shaved rabbit's dorsum on the same day. Dermis concentration profiles were assessed with microdialysis. The gels containing menthol showed higher penetration of drugs than those without whereas the addition of the CCB consistently inhibited the penetration-enhancing effects of menthol. In summary, these findings strongly support the involvement of calcium in the penetration-enhancing effect of menthol. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  1. Do cysteine residues regulate transient receptor potential canonical type 6 (TRPC6) channel protein expression?

    DEFF Research Database (Denmark)

    Thilo, Florian; Liu, Ying; Krueger, Katharina

    2012-01-01

    The regulation of calcium influx through transient receptor potential canonical type 6 channel is mandatory for the activity of human monocytes. We submit the first evidence that cysteine residues of homocysteine or acetylcysteine affect TRPC6 expression in human monocytes. We observed that patie......The regulation of calcium influx through transient receptor potential canonical type 6 channel is mandatory for the activity of human monocytes. We submit the first evidence that cysteine residues of homocysteine or acetylcysteine affect TRPC6 expression in human monocytes. We observed...... that patients with chronic renal failure had significantly elevated homocysteine levels and TRPC6 mRNA expression levels in monocytes compared to control subjects. We further observed that administration of homocysteine or acetylcysteine significantly increased TRPC6 channel protein expression compared...

  2. Transient filament stretching rheometer II

    DEFF Research Database (Denmark)

    Kolte, Mette Irene; Rasmussen, Henrik K.; Hassager, Ole

    1997-01-01

    The Lagrangian sspecification is used to simulate the transient stretching filament rheometer. Simulations are performed for dilute PIB-solutions modeled as a four mode Oldroyd-B fluid and a semidilute PIB-solution modeled as a non-linear single integral equation. The simulations are compared...

  3. Topological specificity and hierarchical network of the circadian calcium rhythm in the suprachiasmatic nucleus.

    Science.gov (United States)

    Enoki, Ryosuke; Kuroda, Shigeru; Ono, Daisuke; Hasan, Mazahir T; Ueda, Tetsuo; Honma, Sato; Honma, Ken-ichi

    2012-12-26

    The circadian pacemaker in the hypothalamic suprachiasmatic nucleus (SCN) is a hierarchical multioscillator system in which neuronal networks play crucial roles in expressing coherent rhythms in physiology and behavior. However, our understanding of the neuronal network is still incomplete. Intracellular calcium mediates the input signals, such as phase-resetting stimuli, to the core molecular loop involving clock genes for circadian rhythm generation and the output signals from the loop to various cellular functions, including changes in neurotransmitter release. Using a unique large-scale calcium imaging method with genetically encoded calcium sensors, we visualized intracellular calcium from the entire surface of SCN slice in culture including the regions where autonomous clock gene expression was undetectable. We found circadian calcium rhythms at a single-cell level in the SCN, which were topologically specific with a larger amplitude and more delayed phase in the ventral region than the dorsal. The robustness of the rhythm was reduced but persisted even after blocking the neuronal firing with tetrodotoxin (TTX). Notably, TTX dissociated the circadian calcium rhythms between the dorsal and ventral SCN. In contrast, a blocker of gap junctions, carbenoxolone, had only a minor effect on the calcium rhythms at both the single-cell and network levels. These results reveal the topological specificity of the circadian calcium rhythm in the SCN and the presence of coupled regional pacemakers in the dorsal and ventral regions. Neuronal firings are not necessary for the persistence of the calcium rhythms but indispensable for the hierarchical organization of rhythmicity in the SCN.

  4. Elemental calcium intake associated with calcium acetate/calcium carbonate in the treatment of hyperphosphatemia.

    Science.gov (United States)

    Wilson, Rosamund J; Copley, J Brian

    2017-01-01

    Calcium-based and non-calcium-based phosphate binders have similar efficacy in the treatment of hyperphosphatemia; however, calcium-based binders may be associated with hypercalcemia, vascular calcification, and adynamic bone disease. A post hoc analysis was carried out of data from a 16-week, Phase IV study of patients with end-stage renal disease (ESRD) who switched to lanthanum carbonate monotherapy from baseline calcium acetate/calcium carbonate monotherapy. Of the intent-to-treat population (N=2520), 752 patients with recorded dose data for calcium acetate (n=551)/calcium carbonate (n=201) at baseline and lanthanum carbonate at week 16 were studied. Elemental calcium intake, serum phosphate, corrected serum calcium, and serum intact parathyroid hormone levels were analyzed. Of the 551 patients with calcium acetate dose data, 271 (49.2%) had an elemental calcium intake of at least 1.5 g/day at baseline, and 142 (25.8%) had an intake of at least 2.0 g/day. Mean (95% confidence interval [CI]) serum phosphate levels were 6.1 (5.89, 6.21) mg/dL at baseline and 6.2 (6.04, 6.38) mg/dL at 16 weeks; mean (95% CI) corrected serum calcium levels were 9.3 (9.16, 9.44) mg/dL and 9.2 (9.06, 9.34) mg/dL, respectively. Of the 201 patients with calcium carbonate dose data, 117 (58.2%) had an elemental calcium intake of at least 1.5 g/day, and 76 (37.8%) had an intake of at least 2.0 g/day. Mean (95% CI) serum phosphate levels were 5.8 (5.52, 6.06) mg/dL at baseline and 5.8 (5.53, 6.05) mg/dL at week 16; mean (95% CI) corrected serum calcium levels were 9.7 (9.15, 10.25) mg/dL and 9.2 (9.06, 9.34) mg/dL, respectively. Calcium acetate/calcium carbonate phosphate binders, taken to control serum phosphate levels, may result in high levels of elemental calcium intake. This may lead to complications related to calcium balance.

  5. Limestone reaction in calcium aluminate cement–calcium sulfate systems

    OpenAIRE

    Bizzozero, Julien; Scrivener, Karen

    2015-01-01

    This paper reports a study of ternary blends composed of calcium aluminate cement, calcium sulfate hemihydrate and limestone. Compressive strength tests and hydration kinetics were studied as a function of limestone and calcium sulfate content. The phase evolution and the total porosity were followed and compared to thermodynamic simulation to understand the reactions involved and the effect of limestone on these binders. The reaction of limestone leads to the formation of hemicarboaluminate ...

  6. Mixed calcium-magnesium pre-nucleation clusters enrich calcium

    OpenAIRE

    Verch, Andreas; Antonietti, Markus; Cölfen, Helmut

    2012-01-01

    It is demonstrated that magnesium and carbonate ions can form pre-nucleation clusters in analogy to calcium carbonate. If a mixed calcium and magnesium solution is brought in contact with carbonate ions, mixed pre-nucleation clusters form. The equilibrium constants for their formation are reported revealing that over the entire range of possible cation mixing ratios, calcium gets enriched over magnesium in the pre-nucleation clusters. This can explain high magnesium contents in amorphous calc...

  7. Stability and delay sensitivity of neutral fractional-delay systems

    Science.gov (United States)

    Xu, Qi; Shi, Min; Wang, Zaihua

    2016-08-01

    This paper generalizes the stability test method via integral estimation for integer-order neutral time-delay systems to neutral fractional-delay systems. The key step in stability test is the calculation of the number of unstable characteristic roots that is described by a definite integral over an interval from zero to a sufficient large upper limit. Algorithms for correctly estimating the upper limits of the integral are given in two concise ways, parameter dependent or independent. A special feature of the proposed method is that it judges the stability of fractional-delay systems simply by using rough integral estimation. Meanwhile, the paper shows that for some neutral fractional-delay systems, the stability is extremely sensitive to the change of time delays. Examples are given for demonstrating the proposed method as well as the delay sensitivity.

  8. Fabrications of zinc-releasing biocement combining zinc calcium phosphate to calcium phosphate cement.

    Science.gov (United States)

    Horiuchi, Shinya; Hiasa, Masahiro; Yasue, Akihiro; Sekine, Kazumitsu; Hamada, Kenichi; Asaoka, Kenzo; Tanaka, Eiji

    2014-01-01

    Recently, zinc-releasing bioceramics have been the focus of much attention owing to their bone-forming ability. Thus, some types of zinc-containing calcium phosphate (e.g., zinc-doped tricalcium phosphate and zinc-substituted hydroxyapatite) are examined and their osteoblastic cell responses determined. In this investigation, we studied the effects of zinc calcium phosphate (ZCP) derived from zinc phosphate incorporated into calcium phosphate cement (CPC) in terms of its setting reaction and MC3T3-E1 osteoblast-like cell responses. Compositional analysis by powder X-ray diffraction analysis revealed that HAP crystals were precipitated in the CPC containing 10 or 30wt% ZCP after successfully hardening. However, the crystal growth observed by scanning electron microscopy was delayed in the presence of additional ZCP. These findings indicate that the additional zinc inhibits crystal growth and the conversion of CPC to the HAP crystals. The proliferation of the cells and alkaline phosphatase (ALP) activity were enhanced when 10wt% ZCP was added to CPC. Taken together, ZCP added CPC at an appropriate fraction has a potent promotional effect on bone substitute biomaterials. © 2013 Elsevier Ltd. All rights reserved.

  9. Association of the Igamma and Idelta charge movement with calcium release in frog skeletal muscle.

    Science.gov (United States)

    Hui, Chiu Shuen

    2005-02-01

    Charge movement and calcium transient were measured simultaneously in stretched frog cut twitch fibers under voltage clamp, with the internal solution containing 20 mM EGTA plus added calcium and antipyrylazo III. When the nominal free [Ca2+]i was 10 nM, the shape of the broad I(gamma) hump in the ON segments of charge movement traces remained invariant when the calcium release rate was greatly diminished. When the nominal free [Ca2+]i was 50 nM, which was close to the physiological level, the I(gamma) humps were accelerated and a slow calcium-dependent I(delta) component (or state) was generated. The peak of ON I(delta) synchronized perfectly with the peak of the calcium release rate whereas the slow decay of ON I(delta) followed the same time course as the decay of calcium release rate. Suppression of calcium release by TMB-8 reduced the amount of Q(delta) concomitantly but not completely, and the effects were partially reversible. The same simultaneous suppression effects were achieved by depleting the sarcoplasmic reticulum calcium store with repetitive stimulation. The results suggest that the mobility of Q(delta) needs to be primed by a physiological level of resting myoplasmic Ca2+. Once the priming is completed, more I(delta) is mobilized by the released Ca2+ during depolarization.

  10. Effects of calcium intake on the cardiovascular system in postmenopausal women.

    Science.gov (United States)

    Challoumas, D; Cobbold, C; Dimitrakakis, G

    2013-11-01

    The use of calcium supplements for the prevention of complications of osteoporosis has significantly increased during the last years. The effects of calcium intake in postmenopausal women on cardiovascular parameters such as blood pressure, serum lipids and cardiovascular events are controversial. Even though transient beneficial effects of calcium supplementation have been reported, especially in women with low dietary calcium intake, their long-term outcomes are inconclusive. Only a very few studies investigating serum lipids in postmenopausal women have been described and these showed significant increases in high-density lipoprotein and high-density lipoprotein to low-density lipoprotein ratio. With regards to cardiovascular events in this population group adverse effects have been reported on the rates of myocardial infarction and stroke with increased calcium intake by some authors, however, others described no effects or even beneficial outcomes. We present a review of the current literature which provides a balanced summary of the possible beneficial and adverse effects of calcium intake in postmenopausal women on cardiovascular parameters. Taking into account the modest effect of calcium supplementation in reducing fracture rates, a reassessment of the role, benefits and adverse effects of calcium supplements should be conducted in postmenopausal women. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  11. Biological Reactions to Calcium Phosphate-coated Calcium Carbonate Particles

    National Research Council Canada - National Science Library

    Tetsunari NISHIKAWA; Kazuya MASUNO; Tomoharu OKAMURA; Kazuya TOMINAGA; Masahiro WATO; Mayu KOKUBU; Koichi IMAI; Shoji TAKEDA; Yoichro TAGUCHI; Masatoshi UEDA; Akio TANAKA

    2010-01-01

    [SYNOPSIS][Objectives]: In order to histopathologically investigate biological reactions to materials used for scaffolds, we examined the cytotoxicity to calcium particles in vitro and bioabsorption in vivo...

  12. A Prospective Study on Role of Supplemental Oral Calcium and Vitamin D in Prevention of Postthyroidectomy Hypocalcemia

    OpenAIRE

    Krishnan Ravikumar; Dhalapathy Sadacharan; Sankaran Muthukumar; Thalavai Sundarram; Selladurai Periyasamy; Suresh, R. V.

    2017-01-01

    Background: Postoperative transient hypocalcemia is sequelae of total thyroidectomy (TT), which is observed in up to 50% of patients. Routine oral calcium and Vitamin D supplementation have been proposed to prevent symptomatic hypocalcemia preventing morbidity and facilitating early discharge. Patients and Methods: A total of 208 patients with nontoxic benign thyroid disorders, undergoing TT, were serially randomized into four groups: Group A (no supplements were given), Group B (oral calcium...

  13. A model of calcium homeostasis in the rat.

    Science.gov (United States)

    Granjon, David; Bonny, Olivier; Edwards, Aurélie

    2016-11-01

    We developed a model of calcium homeostasis in the rat to better understand the impact of dysfunctions such as primary hyperparathyroidism and vitamin D deficiency on calcium balance. The model accounts for the regulation of calcium intestinal uptake, bone resorption, and renal reabsorption by parathyroid hormone (PTH), vitamin D 3 , and Ca 2+ itself. It is the first such model to incorporate recent findings regarding the role of the calcium-sensing receptor (CaSR) in the kidney, the presence of a rapidly exchangeable pool in bone, and the delayed response of vitamin D 3 synthesis. Accounting for two (fast and slow) calcium storage compartments in bone allows the model to properly predict the effects of bisphophonates on the plasma levels of Ca 2+ ([Ca 2+ ] p ), PTH, and vitamin D 3 Our model also suggests that Ca 2+ exchange rates between plasma and the fast pool vary with both sex and age, allowing [Ca 2+ ] p to remain constant in spite of sex- and age-based hormonal and other differences. Our results suggest that the inconstant hypercalciuria that is observed in primary hyperparathyroidism can be attributed in part to counterbalancing effects of PTH and CaSR in the kidney. Our model also correctly predicts that calcimimetic agents such as cinacalcet bring down [Ca 2+ ] p to within its normal range in primary hyperparathyroidism. In addition, the model provides a simulation of CYP24A1 inactivation that leads to a situation reminiscent of infantile hypercalcemia. In summary, our model of calcium handling can be used to decipher the complex regulation of calcium homeostasis. Copyright © 2016 the American Physiological Society.

  14. Delayed cure bismaleimide resins

    Science.gov (United States)

    Adams, Johnnie E.; Jamieson, Donald R.

    1984-08-07

    Polybismaleimides prepared by delayed curing of bis-imides having the formula ##STR1## wherein R.sub.1 and R.sub.2 each independently is H, C.sub.1-4 -alkyl, C.sub.1-4 -alkoxy, Cl or Br, or R.sub.1 and R.sub.2 together form a fused 6-membered hydrocarbon aromatic ring, with the proviso that R.sub.1 and R.sub.2 are not t-butyl or t-butoxy; X is O, S or Se; n is 1-3; and the --(CH.sub.2).sub.n -- group, optionally, is substituted by 1-3 methyl groups or by fluorine.

  15. Delay tolerant networks

    CERN Document Server

    Gao, Longxiang; Luan, Tom H

    2015-01-01

    This brief presents emerging and promising communication methods for network reliability via delay tolerant networks (DTNs). Different from traditional networks, DTNs possess unique features, such as long latency and unstable network topology. As a result, DTNs can be widely applied to critical applications, such as space communications, disaster rescue, and battlefield communications. The brief provides a complete investigation of DTNs and their current applications, from an overview to the latest development in the area. The core issue of data forward in DTNs is tackled, including the importance of social characteristics, which is an essential feature if the mobile devices are used for human communication. Security and privacy issues in DTNs are discussed, and future work is also discussed.

  16. Synchronizing time delay systems using variable delay in coupling

    Energy Technology Data Exchange (ETDEWEB)

    Ambika, G., E-mail: g.ambika@iiserpune.ac.in [Indian Institute of Science Education and Research, Pune 411 021 (India); Amritkar, R.E., E-mail: amritkar@prl.res.in [Physical Research Laboratory, Ahmedabad 380 009 (India)

    2011-11-15

    Highlights: > Delay and anticipation in coupling function varies with system dynamics. > Delay or anticipation of the synchronized state is independent of system delay. > Stability analysis developed is quite general. > We demonstrate enhanced security in communication. > Generalized synchronization possible over a wide range of parameter mismatch. - Abstract: We present a mechanism for synchronizing time delay systems using one way coupling with a variable delay in coupling that is reset at finite intervals. We present the analysis of the error dynamics that helps to isolate regions of stability of the synchronized state in the parameter space of interest for single and multiple delays. We supplement this by numerical simulations in a standard time delay system like Mackey Glass system. This method has the advantage that it can be adjusted to be delay or anticipatory in synchronization with a time which is independent of the system delay. We demonstrate the use of this method in communication using the bi channel scheme. We show that since the synchronizing channel carries information from transmitter only at intervals of reset time, it is not susceptible to an easy reconstruction.

  17. Osteoporosis, calcium and physical activity.

    OpenAIRE

    Martin, A. D.; Houston, C S

    1987-01-01

    Sales of calcium supplements have increased dramatically since 1983, as middle-aged women seek to prevent or treat bone loss due to osteoporosis. However, epidemiologic studies have failed to support the hypothesis that larger amounts of calcium are associated with increased bone density or a decreased incidence of fractures. The authors examine the evidence from controlled trials on the effects of calcium supplementation and physical activity on bone loss and find that weight-bearing activit...

  18. The effects of thermal stimuli on intracellular calcium change and histamine releases in rat basophilic leukemia mast cells

    Science.gov (United States)

    Wu, Zu-Hui; Zhu, Dan; Chen, Ji-Yao; Zhou, Lu-Wei

    2012-05-01

    The effects of thermal stimuli on rat basophilic leukemia mast cells were studied. The cells in calcium-contained or calcium-free buffers were thermally stimulated in the temperature range of 25-60 °C. The corresponding calcium ion concentration in cells [Ca2+]i as well as the released histamine from cells was measured with fluorescence staining methods. The ruthenium red (RR), a block of membrane calcium channels (transient receptor potential family V (TRPV)), was used in experiments. Under the stimulus of 25-50 °C, no significant difference on [Ca2+]i was found between these three groups of the cells in calcium-contained buffer without or with RR and cells in calcium-free saline, indicating that the increased calcium in cytosol did not result from the extracellular buffer but came from the intracellular calcium stores. The [Ca2+]i continuously increased under the temperature of 50-60 °C, but the RR and calcium-free saline can obviously diminish the [Ca2+]i increase at these high temperatures, reflecting that the opening of the TRPV2 channels leads to a calcium influx resulting in the [Ca2+]i increment. The histamine release also became significant in these cases. Since the released histamine is a well-known mediator for the microcirculation promotion, the histamine release from mast cells could be one of the mechanisms of thermal therapy.

  19. Structural dynamics of the cell nucleus: basis for morphology modulation of nuclear calcium signaling and gene transcription.

    Science.gov (United States)

    Queisser, Gillian; Wiegert, Simon; Bading, Hilmar

    2011-01-01

    Neuronal morphology plays an essential role in signal processing in the brain. Individual neurons can undergo use-dependent changes in their shape and connectivity, which affects how intracellular processes are regulated and how signals are transferred from one cell to another in a neuronal network. Calcium is one of the most important intracellular second messengers regulating cellular morphologies and functions. In neurons, intracellular calcium levels are controlled by ion channels in the plasma membrane such as NMDA receptors (NMDARs), voltage-gated calcium channels (VGCCs) and certain α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) as well as by calcium exchange pathways between the cytosol and internal calcium stores including the endoplasmic reticulum and mitochondria. Synaptic activity and the subsequent opening of ligand and/or voltage-gated calcium channels can initiate cytosolic calcium transients which propagate towards the cell soma and enter the nucleus via its nuclear pore complexes (NPCs) embedded in the nuclear envelope. We recently described the discovery that in hippocampal neurons the morphology of the nucleus affects the calcium dynamics within the nucleus. Here we propose that nuclear infoldings determine whether a nucleus functions as an integrator or detector of oscillating calcium signals. We outline possible ties between nuclear mophology and transcriptional activity and discuss the importance of extending the approach to whole cell calcium signal modeling in order to understand synapse-to-nucleus communication in healthy and dysfunctional neurons.

  20. Cardiovascular Effects of Calcium Supplements

    Directory of Open Access Journals (Sweden)

    Ian R. Reid

    2013-07-01

    Full Text Available Calcium supplements reduce bone turnover and slow the rate of bone loss. However, few studies have demonstrated reduced fracture incidence with calcium supplements, and meta-analyses show only a 10% decrease in fractures, which is of borderline statistical and clinical significance. Trials in normal older women and in patients with renal impairment suggest that calcium supplements increase the risk of cardiovascular disease. To further assess their safety, we recently conducted a meta-analysis of trials of calcium supplements, and found a 27%–31% increase in risk of myocardial infarction, and a 12%–20% increase in risk of stroke. These findings are robust because they are based on pre-specified analyses of randomized, placebo-controlled trials and are consistent across the trials. Co-administration of vitamin D with calcium does not lessen these adverse effects. The increased cardiovascular risk with calcium supplements is consistent with epidemiological data relating higher circulating calcium concentrations to cardiovascular disease in normal populations. There are several possible pathophysiological mechanisms for these effects, including effects on vascular calcification, vascular cells, blood coagulation and calcium-sensing receptors. Thus, the non-skeletal risks of calcium supplements appear to outweigh any skeletal benefits, and are they appear to be unnecessary for the efficacy of other osteoporosis treatments.

  1. Laser Sintered Calcium Phosphate Bone

    National Research Council Canada - National Science Library

    Vail, Neil

    1999-01-01

    ...) technology selective laser sintering (SLS). BME has successfully implemented a pilot facility to fabricate calcium phosphate implants using anatomical data coupled with the selective laser sintering process...

  2. Concurrent Delay in Construction Disputes

    DEFF Research Database (Denmark)

    Cavaleri, Sylvie Cécile

    Delay is one of the issues most frequently encountered in today’s construction industry; it causes significant economic damage to all parties involved. Construction contracts, standard and bespoke, almost invariably consider delay from a perspective of single liability. If the event causing...... solutions to the issue of concurrent delay in a comparative perspective between common and civil law systems, with an emphasis on Danish and English law....

  3. Location Estimation using Delayed Measurements

    DEFF Research Database (Denmark)

    Bak, Martin; Larsen, Thomas Dall; Nørgård, Peter Magnus

    1998-01-01

    When combining data from various sensors it is vital to acknowledge possible measurement delays. Furthermore, the sensor fusion algorithm, often a Kalman filter, should be modified in order to handle the delay. The paper examines different possibilities for handling delays and applies a new...... technique to a sensor fusion system for estimating the location of an autonomous guided vehicle. The system fuses encoder and vision measurements in an extended Kalman filter. Results from experiments in a real environment are reported...

  4. A comparison of sodium calcium edetate (edetate calcium disodium) and succimer (DMSA) in the treatment of inorganic lead poisoning.

    Science.gov (United States)

    Bradberry, Sally; Vale, Allister

    2009-11-01

    were found, though no direct comparison between antidotes was undertaken. DMSA was more effective than sodium calcium edetate in reducing the kidney lead concentration, sodium calcium edetate was more effective than DMSA in reducing bone lead concentrations, and there was no consistently observed effect of chelation therapy on brain lead concentrations in these experimental studies. Only two clinical studies have compared equimolar or similar antidote doses in enhancing urine lead excretion; there was no statistical difference between the antidotes, though both studies had limitations. DMSA and sodium calcium edetate had a comparable impact on lowering blood lead concentrations in a clinical study using similar molar antidote doses. Sodium calcium edetate causes dose-related nephrotoxicity. Both agents deplete zinc and copper, the effect on zinc being significantly greater with sodium calcium edetate. A transient increase in hepatic transaminase activity has been reported with both antidotes but appears to be more common with DMSA and neither has been associated with clinically significant hepatic toxicity. Skin lesions during treatment with sodium calcium edetate are unusual and have been attributed to zinc deficiency. DMSA has occasionally been associated with a severe mucocutaneous reaction necessitating discontinuation of therapy. Oral DMSA and parenteral sodium calcium edetate are both effective chelators of lead. There are currently insufficient data, however, to conclude that either antidote is superior in enhancing lead excretion. Both antidotes resolve the symptoms of moderate and severe lead toxicity rapidly. Although there is greater clinical experience with sodium calcium edetate, particularly in the treatment of lead encephalopathy, oral DMSA may now be considered as an alternative in circumstances where oral therapy is preferable.

  5. Modeling delay in genetic networks: from delay birth-death processes to delay stochastic differential equations.

    Science.gov (United States)

    Gupta, Chinmaya; López, José Manuel; Azencott, Robert; Bennett, Matthew R; Josić, Krešimir; Ott, William

    2014-05-28

    Delay is an important and ubiquitous aspect of many biochemical processes. For example, delay plays a central role in the dynamics of genetic regulatory networks as it stems from the sequential assembly of first mRNA and then protein. Genetic regulatory networks are therefore frequently modeled as stochastic birth-death processes with delay. Here, we examine the relationship between delay birth-death processes and their appropriate approximating delay chemical Langevin equations. We prove a quantitative bound on the error between the pathwise realizations of these two processes. Our results hold for both fixed delay and distributed delay. Simulations demonstrate that the delay chemical Langevin approximation is accurate even at moderate system sizes. It captures dynamical features such as the oscillatory behavior in negative feedback circuits, cross-correlations between nodes in a network, and spatial and temporal information in two commonly studied motifs of metastability in biochemical systems. Overall, these results provide a foundation for using delay stochastic differential equations to approximate the dynamics of birth-death processes with delay.

  6. Mean, covariance, and effective dimension of stochastic distributed delay dynamics

    Science.gov (United States)

    René, Alexandre; Longtin, André

    2017-11-01

    Dynamical models are often required to incorporate both delays and noise. However, the inherently infinite-dimensional nature of delay equations makes formal solutions to stochastic delay differential equations (SDDEs) challenging. Here, we present an approach, similar in spirit to the analysis of functional differential equations, but based on finite-dimensional matrix operators. This results in a method for obtaining both transient and stationary solutions that is directly amenable to computation, and applicable to first order differential systems with either discrete or distributed delays. With fewer assumptions on the system's parameters than other current solution methods and no need to be near a bifurcation, we decompose the solution to a linear SDDE with arbitrary distributed delays into natural modes, in effect the eigenfunctions of the differential operator, and show that relatively few modes can suffice to approximate the probability density of solutions. Thus, we are led to conclude that noise makes these SDDEs effectively low dimensional, which opens the possibility of practical definitions of probability densities over their solution space.

  7. 21 CFR 73.1070 - Calcium carbonate.

    Science.gov (United States)

    2010-04-01

    ... precipitated calcium carbonate (CaCO3). (2) Color additive mixtures for drug use made with calcium carbonate... precipitated calcium carbonate in the United States Pharmacopeia XX (1980). (c) Uses and restrictions. Calcium... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Calcium carbonate. 73.1070 Section 73.1070 Food...

  8. 21 CFR 184.1191 - Calcium carbonate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium carbonate. 184.1191 Section 184.1191 Food... Specific Substances Affirmed as GRAS § 184.1191 Calcium carbonate. (a) Calcium carbonate (CaCO3, CAS Reg... soda process”; (2) By precipitation of calcium carbonate from calcium hydroxide in the “Carbonation...

  9. Effects of 1,25-Dihydroxycholecalciferol on Recovery and Resolution of Late Transient Neonatal Hypocalcemia

    Directory of Open Access Journals (Sweden)

    McKay SiripoomV

    2010-03-01

    Full Text Available Background. Late transient neonatal hypocalcemia with hyperphosphatemia is potentially life-threatening. The use of dihydroxycholecalciferol in the management of neonatal hypocalcemia is unexplored. Objective. We hypothesized adding dihydroxycholecalciferol to intravenous continuous calcium infusion (CaI will achieve accelerated correction of hypocalcemia. Design/Methods. A controlled double-blind randomized placebo group was organized to compare the addition of dihydroxycholecalciferol to CaI in 3–14 day old neonates presenting with hypocalcemia, hyperphosphatemia and seizures. Ionized calcium and phosphorus were measured to adjust CaI and maintain eucalcemia. Time to resolution of hypocalcemia was defined as time from starting CaI to the first ionized calcium of  mmol/L. CaI was discontinued when ionized calcium levels were  mmol/L on two measurements and the infant tolerated feeds. Results. Fourteen neonates were studied without statistical difference between groups. Time to correction of hypocalcemia for 1,25 dihydroxycholecalciferol versus placebo was versus hours respectively (. The duration of CaI was versus hours respectively (. Conclusions. The addition of dihydroxycholecalciferol to standard CaI therapy reduced the duration of CaI, but did not reduce the time to correct hypocalcemia in neonates with late transient hypocalcemia.

  10. Time Delay of CGM Sensors

    Science.gov (United States)

    Schmelzeisen-Redeker, Günther; Schoemaker, Michael; Kirchsteiger, Harald; Freckmann, Guido; Heinemann, Lutz; del Re, Luigi

    2015-01-01

    Background: Continuous glucose monitoring (CGM) is a powerful tool to support the optimization of glucose control of patients with diabetes. However, CGM systems measure glucose in interstitial fluid but not in blood. Rapid changes in one compartment are not accompanied by similar changes in the other, but follow with some delay. Such time delays hamper detection of, for example, hypoglycemic events. Our aim is to discuss the causes and extent of time delays and approaches to compensate for these. Methods: CGM data were obtained in a clinical study with 37 patients with a prototype glucose sensor. The study was divided into 5 phases over 2 years. In all, 8 patients participated in 2 phases separated by 8 months. A total number of 108 CGM data sets including raw signals were used for data analysis and were processed by statistical methods to obtain estimates of the time delay. Results: Overall mean (SD) time delay of the raw signals with respect to blood glucose was 9.5 (3.7) min, median was 9 min (interquartile range 4 min). Analysis of time delays observed in the same patients separated by 8 months suggests a patient dependent delay. No significant correlation was observed between delay and anamnestic or anthropometric data. The use of a prediction algorithm reduced the delay by 4 minutes on average. Conclusions: Prediction algorithms should be used to provide real-time CGM readings more consistent with simultaneous measurements by SMBG. Patient specificity may play an important role in improving prediction quality. PMID:26243773

  11. Delayed visual maturation and autism.

    Science.gov (United States)

    Goodman, R; Ashby, L

    1990-09-01

    Three boys are described with a mixed developmental disorder, which so far appears to have a relatively good prognosis. Each boy presented in early infancy with visual unresponsiveness, which spontaneously resolved. This delayed visual maturation was accompanied or followed by severe autistic impairment, general developmental delay, hypotonia and clumsiness. Subsequent progress has been unexpectedly favourable, with striking improvements in language, play, social interest and social competence. Widespread, patchy delay in brain maturation could possibly account for this combination of delayed visual maturation and autism, with a good prognosis.

  12. Nonlinear Diffusion and Transient Osmosis

    Science.gov (United States)

    Akira, Igarashi; Lamberto, Rondoni; Antonio, Botrugno; Marco, Pizzi

    2011-08-01

    We investigate both analytically and numerically the concentration dynamics of a solution in two containers connected by a narrow and short channel, in which diffusion obeys a porous medium equation. We also consider the variation of the pressure in the containers due to the flow of matter in the channel. In particular, we identify a phenomenon, which depends on the transport of matter across nano-porous membranes, which we call “transient osmosis". We find that nonlinear diffusion of the porous medium equation type allows numerous different osmotic-like phenomena, which are not present in the case of ordinary Fickian diffusion. Experimental results suggest one possible candidate for transiently osmotic processes.

  13. Simulation of Transient Viscoelastic Flow

    DEFF Research Database (Denmark)

    Rasmussen, Henrik Koblitz; Hassager, Ole

    1993-01-01

    The Lagrangian kinematic description is used to develop a numerical method for simulation of time-dependent flow of viscoelastic fluids described by integral models. The method is shown to converge to first order in the time step and at least second order in the spatial discretization. The method...... is tested on the established sphere in a cylinder benchmark problem, and an extension of the problem to transient flow is proposed....

  14. Simulation Model of a Transient

    DEFF Research Database (Denmark)

    Jauch, Clemens; Sørensen, Poul; Bak-Jensen, Birgitte

    2005-01-01

    This paper describes the simulation model of a controller that enables an active-stall wind turbine to ride through transient faults. The simulated wind turbine is connected to a simple model of a power system. Certain fault scenarios are specified and the turbine shall be able to sustain operation...... in case of such faults. The design of the controller is described and its performance assessed by simulations. The control strategies are explained and the behaviour of the turbine discussed....

  15. Calcium signalling: fishing out molecules of mitochondrial calcium transport.

    Science.gov (United States)

    Hajnóczky, György; Csordás, György

    2010-10-26

    Cellular energy metabolism, survival and death are controlled by mitochondrial calcium signals originating in the cytoplasm. Now, RNAi studies link three proteins - MICU1, NCLX and LETM1 - to the previously unknown molecular mechanism of mitochondrial calcium transport. Copyright © 2010 Elsevier Ltd. All rights reserved.

  16. Calcium electroporation in three cell lines; a comparison of bleomycin and calcium, calcium compounds, and pulsing conditions

    DEFF Research Database (Denmark)

    Frandsen, Stine Krog; Gissel, Hanne; Hojman, Pernille

    2013-01-01

    BACKGROUND: Electroporation with calcium (calcium electroporation) can induce ATP depletion-associated cellular death. In the clinical setting, the cytotoxic drug bleomycin is currently used with electroporation (electrochemotherapy) for palliative treatment of tumors. Calcium electroporation off...

  17. Transient virulence of emerging pathogens.

    Science.gov (United States)

    Bolker, Benjamin M; Nanda, Arjun; Shah, Dharmini

    2010-05-06

    Should emerging pathogens be unusually virulent? If so, why? Existing theories of virulence evolution based on a tradeoff between high transmission rates and long infectious periods imply that epidemic growth conditions will select for higher virulence, possibly leading to a transient peak in virulence near the beginning of an epidemic. This transient selection could lead to high virulence in emerging pathogens. Using a simple model of the epidemiological and evolutionary dynamics of emerging pathogens, along with rough estimates of parameters for pathogens such as severe acute respiratory syndrome, West Nile virus and myxomatosis, we estimated the potential magnitude and timing of such transient virulence peaks. Pathogens that are moderately evolvable, highly transmissible, and highly virulent at equilibrium could briefly double their virulence during an epidemic; thus, epidemic-phase selection could contribute significantly to the virulence of emerging pathogens. In order to further assess the potential significance of this mechanism, we bring together data from the literature for the shapes of tradeoff curves for several pathogens (myxomatosis, HIV, and a parasite of Daphnia) and the level of genetic variation for virulence for one (myxomatosis). We discuss the need for better data on tradeoff curves and genetic variance in order to evaluate the plausibility of various scenarios of virulence evolution.

  18. Cortical computations via transient attractors.

    Directory of Open Access Journals (Sweden)

    Oliver L C Rourke

    Full Text Available The ability of sensory networks to transiently store information on the scale of seconds can confer many advantages in processing time-varying stimuli. How a network could store information on such intermediate time scales, between typical neurophysiological time scales and those of long-term memory, is typically attributed to persistent neural activity. An alternative mechanism which might allow for such information storage is through temporary modifications to the neural connectivity which decay on the same second-long time scale as the underlying memories. Earlier work that has explored this method has done so by emphasizing one attractor from a limited, pre-defined set. Here, we describe an alternative, a Transient Attractor network, which can learn any pattern presented to it, store several simultaneously, and robustly recall them on demand using targeted probes in a manner reminiscent of Hopfield networks. We hypothesize that such functionality could be usefully embedded within sensory cortex, and allow for a flexibly-gated short-term memory, as well as conferring the ability of the network to perform automatic de-noising, and separation of input signals into distinct perceptual objects. We demonstrate that the stored information can be refreshed to extend storage time, is not sensitive to noise in the system, and can be turned on or off by simple neuromodulation. The diverse capabilities of transient attractors, as well as their resemblance to many features observed in sensory cortex, suggest the possibility that their actions might underlie neural processing in many sensory areas.

  19. Igniter heater EMI transient test

    Science.gov (United States)

    Cook, M.

    1989-01-01

    Testing to evaluate Redesigned Solid Rocket Motor igniter heater electromagnetic interference (EMI) effects on the Safe and Arm (S and A) device was completed. It was suspected that EMI generated by the igniter heater and it's associated electromechanical relay could cause a premature firing of the NASA Standard Initiators (NSIs) inside the S and A. The maximum voltage induced into the NSI fire lines was 1/4 of the NASA specified no-fire limit of one volt (SKB 26100066). As a result, the igniter heaters are not expected to have any adverse EMI effects on the NSIs. The results did show, however, that power switching causes occasional high transients within the igniter heater power cable. These transients could affect the sensitive equipment inside the forward skirt. It is therefore recommended that the electromechanical igniter heater relays be replaced with zero crossing solid state relays. If the solid state relays are installed, it is also recommended that they be tested for EMI transient effects.

  20. Phorbol ester stimulates calcium sequestration in saponized human platelets

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, K.; Nachmias, V.T.

    1987-11-25

    When platelets are activated by agonists, calcium (Ca2+) is released from an intracellular storage site. Recent studies using fura-2 show that, after thrombin stimulation, the rise in free calcium is transient and returns to base-line levels in 2-3 min, while the transient following ADP stimulation lasts only 15-20 s. We reported previously that the phorbol ester 12,13-phorbol myristate acetate (PMA), added at nanomolar levels after thrombin, immediately accelerated the rate of return of calcium to the base line severalfold. In the present study, we used both intact and saponized platelets to determine whether this is due to stimulation of calcium sequestration. Using fura-2 and intact platelets, we found 1) that PMA stimulated the restoration of free Ca2+ levels after ADP as well as after thrombin, and 2) that H-7, an inhibitor of protein kinase C (Ca2+/phospholipid-dependent enzyme), slowed the return of Ca2+ to baseline levels. Using saponized platelets, we also found 3) that pretreatment of platelets with PMA before saponin treatment increased the ATP-dependent /sup 45/Ca2+ uptake 2-fold, with a half-maximal effect at 5 nm; 4) that most of the Ca2+ released by ionomycin or by myoinositol 1,4,5-trisphosphate; and 5) that a GTP-binding protein inhibitor, guanosine 5'-O-(2-thiodiphosphate), decreased basal or PMA-stimulated /sup 45/Ca2+ uptake in saponin-treated platelets. Our data suggest that activation of protein kinase C stimulates the sequestration of Ca2+ independently of cAMP or myoinositol 1,4,5-trisphosphate.

  1. Delay of gratification and delay discounting in rats.

    Science.gov (United States)

    Reynolds, Brady; de Wit, Harriet; Richards, Jerry

    2002-09-30

    Delay discounting (DD) and delay of gratification (DG) are two measures of impulsive behavior often viewed as reflecting the same or equivalent processes. However, there are some key differences in the contingencies of reinforcement between the procedures that may have implications for understanding impulsivity. This study used DD and DG procedures to determine if differences in contingencies of reinforcement specified by DD and DG alters how much organisms discount the value of delayed reinforcers. Twenty-four water-deprived rats performed one of two Adjusting Amount procedures, which consisted of repeated choices between a fixed amount of water (250 &mgr;l) delivered after a delay (0, 4, 8, 16, or 32 s) and an adjusting, usually lesser amount delivered immediately. Half of the rats (n=12) performed a DD procedure designed to assess preference for immediate over delayed reinforcers in which they had discrete choices between the immediate and delayed amounts of water. A DG procedure was used for the other half of the rats (n=12). In the DG procedure rats also selected between immediate and delayed alternatives, but if they chose the delayed alternative they could switch to and receive the immediate alternative at any time during the delay to the larger reward. In the DD procedure switching responses were not reinforced but were still recorded and used for analyses. The DD functions of the two groups did not differ significantly. However, at the longer delays, the DG group made significantly fewer switching responses than the DD group. A possible role of response inhibition in the DG procedure is discussed.

  2. Boolean delay equations. II. Periodic and aperiodic solutions

    Science.gov (United States)

    Ghil, M.; Mullhaupt, A.

    1985-10-01

    Boolean delay equations (BDEs) are evolution equations for a vector of discrete variables x (t). The value of each component X i ( t), 0 or 1. depends on previous values of all components x j (t- t ij ), x i (t)=f i (x1( t- t i1),..., x n ( t - t in )). BDEs model the evolution of biological and physical systems with threshold behavior and nonlinear feedbacks. The delays model distinct interaction times between pairs of variables. In this paper, BDEs are studied by algebraic, analytic, and numerical methods. It is shown that solutions depend continuously on the initial data and on the delays. BDEs are classified into conservative and dissipative. All BDEs with rational delays only have periodic solutions only. But conservative BDEs with rationally unrelated delays have aperiodic solutions of increasing complexity. These solutions can be approximated arbitrarily well by periodic solutions of increasing period. Self-similarity and intermittency of aperiodic solutions is studied as a function of delay values, and certain number-theoretic questions related to resonances and diophantine approximation are raised. Period length is shown to be a lower semicontinuous function of the delays for a given BDE, and can be evaluated explicitly for linear equations. We prove that a BDE is structurable stable if and only if it has eventually periodic solutions of bounded period, and if the length of initial transients is bounded. It is shown that, for dissipative BDEs, asymptotic solution behavior is typically governed by a reduced BDE. Applications to climate dynamics and other problems are outlined.

  3. Dental Problems in Calcium Metabolism Disorders

    Directory of Open Access Journals (Sweden)

    Ali Rabbani M.D.

    2011-06-01

    Full Text Available Background: Calcium metabolism disorders can be acute or chronic and chronic disorders can cause different disease states such as dental problems. Methods: In this descriptive cross-sectional study done in Children's Medical Center affiliated to Tehran University of Medical Sciences during 2005-2009, all (93 patients with hypoparathyroidism, nutritional rickets, hypophosphatemic rickets and renal osteodysthrophy from the endocrinology and nephrology departments of the Center were referred to a dentist there for orodental examination. Subsequently, the frequency of dental problems including taurodontism, enamel hypoplasia, dental abscess, dental caries and gingivitis were recorded and analyzed. Results: Nutritional rickets was the most common disorder in this study and delay in dentition was the most frequent dental problem in the patients (61.9%. Most cases of taurdontism and enamel hypoplasia were seen in patients with hypoparathyroidism (33% and 50%, respectively. Dental abscess, dental caries and gingivitis were more common in patients with renal osteodysthrophia (50%, 90% and 20%, respectively. In addition, dental caries and delay in dentition were the most prevalent disorders in this study (69.8% and 49.5%, respectively. Conclusion: According to the above findings, it seems that effective screening, regular periodic examinations, proper diagnosis and timely treatment of dental diseases are the main principles of prevention of orodental problems. Moreover, dentists as well as pediatricians should be aware of the features of the aforesaid disorders which lead to dental problems so that early intervention could prevent subsequent serious and more invasive dental problems.

  4. Apical Revascularization after Delayed Tooth Replantation: An Unusual Case

    OpenAIRE

    Marília Pacífico Lucisano; Paulo Nelson-Filho; Lea Assed Bezerra Silva; Raquel Assed Bezerra Silva; Fabricio Kitazono de Carvalho; Alexandra Mussolino de Queiroz

    2016-01-01

    The aim of this paper is to present the clinical and radiological outcome of the treatment involving a delayed tooth replantation after an avulsed immature permanent incisor, with a follow-up of 1 year and 6 months. An 8-year-old boy was referred after dental trauma that occurred on the previous day. The permanent maxillary right central incisor (tooth 11) had been avulsed. The tooth was hand-held during endodontic therapy and an intracanal medication application with calcium hydroxide-based ...

  5. Calcium, vitamin D, and your bones

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/patientinstructions/000490.htm Calcium, vitamin D, and your bones To use the sharing ... and maintain strong bones. How Much Calcium and Vitamin D do I Need? Amounts of calcium are ...

  6. Calcium Supplements: Do Men Need Them Too?

    Science.gov (United States)

    ... Lifestyle Nutrition and healthy eating Should men take calcium supplements? Answers from Katherine Zeratsky, R.D., L. ... Most healthy men don't need to take calcium supplements. Calcium is important for men for optimal ...

  7. Desensitization of delayed-type hypersensitivity in mice: suppressive environment

    Directory of Open Access Journals (Sweden)

    Takashi Katsura

    1993-01-01

    Full Text Available The systemic injection of high doses of antigen into a preimmunized animal results in transient unresponsiveness of cell-mediated immune responses. This phenomenon is known as desensitization. Serum interleukin 2 (IL-2 activity was found transiently in desensitized mice at 3 h after the antigen challenge. These mice could not reveal antigen nonspecific delayed-type hypersensitivity (DTH 1 d after the challenge. Specific suppression of DTH was observed at later stages. Sera from 3 h desensitized mice showed suppressive effects on DTH in preo immunized mice. Administration of recombinant IL-2 into preimmunized mice led to the failure of development of DTH to antigens. These observations suggest that IL-2 plays an important role in the suppressive environment.

  8. Intercellular calcium signaling and nitric oxide feedback during constriction of rabbit renal afferent arterioles

    DEFF Research Database (Denmark)

    Uhrenholt, Torben Rene; Schjerning, J; Vanhoutte, Paul M. G.

    2007-01-01

    calciseptine. After a delay of 10 s, [Ca(2+)](i) increased in endothelial cells immediately adjacent to reactive smooth muscle cells, and this calcium wave spread in a nonregenerative fashion laterally into the endothelial cell layer with a velocity of 1.2 microm/s. Depolarization with 100 mmol/l KCl led...

  9. Delay dynamic equations with stability

    Directory of Open Access Journals (Sweden)

    Krueger Robert J

    2006-01-01

    Full Text Available We first give conditions which guarantee that every solution of a first order linear delay dynamic equation for isolated time scales vanishes at infinity. Several interesting examples are given. In the last half of the paper, we give conditions under which the trivial solution of a nonlinear delay dynamic equation is asymptotically stable, for arbitrary time scales.

  10. Registration Delay and Student Performance

    Science.gov (United States)

    Siefken, Jason

    2017-01-01

    Tracking the difference between the time a first-year student is allowed to register for a course and the time he or she does register for a course (a student's registration delay), we notice a negative correlation between registration delay and final grade in a course. The difference between a student who registers within the first two minutes…

  11. Delayed Reinforcement of Operant Behavior

    Science.gov (United States)

    Lattal, Kennon A.

    2010-01-01

    The experimental analysis of delay of reinforcement is considered from the perspective of three questions that seem basic not only to understanding delay of reinforcement but also, by implication, the contributions of temporal relations between events to operant behavior. The first question is whether effects of the temporal relation between…

  12. #FakeNobelDelayReasons

    CERN Document Server

    2013-01-01

    Tuesday’s hour-long delay of the Nobel Prize in Physics announcement was (and still is) quite the cause for speculation. But on the Twittersphere, it was simply the catalyst for some fantastic puns, so-bad-they're-good physics jokes and other shenanigans. Here are some of our favourite #FakeNobelDelayReasons.    

  13. Transient band keratopathy associated with ocular inflammation and systemic hypercalcemia

    Directory of Open Access Journals (Sweden)

    Anat Galor

    2008-10-01

    Full Text Available Anat Galor, Henry A Leder, Jennifer E Thorne, James P DunnThe Wilmer Eye Institute, Department of Ophthalmology, the Johns Hopkins University School of MedicinePurpose: To report a case of visually significant band keratopathy associated with ocular inflammation and systemic hypercalcemia which markedly decreased in severity after treatment of these underlying factors.Methods: Retrospective case report.Results: A 53-year-old Asian female with granulomatous panuveitis in the left eye presented with diffuse band keratopathy through the central cornea. The serum calcium was elevated. The patient was treated with topical prednisolone acetate 1% and oral prednisone with marked improvement in inflammation. The band keratopathy lessened in severity with clearing of the central cornea and improvement in visual acuity.Conclusions: Early medical treatment of underlying factors may allow reversal of band keratopathy.Keywords: ocular inflammation, transient band keratopathy

  14. Transient noise suppression algorithm in speech system

    Science.gov (United States)

    Cao, Keyu; Wang, Mingjiang

    2017-08-01

    In this paper, I mainly introduce the algorithm of transient noise suppression in speech system. Firstly, it divides into impulsive noise and other types of transient noise according to the characteristics of transient noise. In the impulse noise suppression algorithm, I mainly use the averaging energy threshold method to detect the impulse noise, and then I use the amplitude threshold method to reduce the impulse noise which was detected. In the other types of transient noise suppression algorithm, I mainly use the Optimally Modified-Log Spectral Amplitude estimation (OM-LSA) algorithm and the Minimum Control Recursive Average (MCRA) algorithm to suppress the transient noise.

  15. Identification of a Calcium Signalling Pathway of S-[6]-Gingerol in HuH-7 Cells

    Directory of Open Access Journals (Sweden)

    Xiao-Hong Li

    2013-01-01

    Full Text Available Calcium signals in hepatocytes control cell growth, proliferation, and death. Members of the transient receptor potential (TRP cation channel superfamily are candidate calcium influx channels. NFκB activation strictly depends on calcium influx and often induces antiapoptotic genes favouring cell survival. Previously, we reported that S-[6]-gingerol is an efficacious agonist of the transient receptor potential cation channel subfamily V member 1 (TRPV1 in neurones. In this study, we tested the effect of S-[6]-gingerol on HuH-7 cells using the Fluo-4 calcium assay, RT-qPCR, transient cell transfection, and luciferase measurements. We found that S-[6]-gingerol induced a transient rise in [Ca2+]i in HuH-7 cells. The increase in [Ca2+]i induced by S-[6]-gingerol was abolished by preincubation with EGTA and was also inhibited by the TRPV1 channel antagonist capsazepine. Expression of TRPV1 in HuH-7 cells was confirmed by mRNA analysis as well as a test for increase of [Ca2+]i by TRPV1 agonist capsaicin and its inhibition by capsazepine. We found that S-[6]-gingerol induced rapid NFκB activation through TRPV1 in HuH-7 cells. Furthermore, S-[6]-gingerol-induced NFκB activation was dependent on the calcium gradient and TRPV1. The rapid NFκB activation by S-[6]-gingerol was associated with an increase in mRNA levels of NFκB-target genes: cIAP-2, XIAP, and Bcl-2 that encode antiapoptotic proteins.

  16. Stable prenucleation calcium carbonate clusters.

    Science.gov (United States)

    Gebauer, Denis; Völkel, Antje; Cölfen, Helmut

    2008-12-19

    Calcium carbonate forms scales, geological deposits, biominerals, and ocean sediments. Huge amounts of carbon dioxide are retained as carbonate ions, and calcium ions represent a major contribution to water hardness. Despite its relevance, little is known about the precipitation mechanism of calcium carbonate, and specified complex crystal structures challenge the classical view on nucleation considering the formation of metastable ion clusters. We demonstrate that dissolved calcium carbonate in fact contains stable prenucleation ion clusters forming even in undersaturated solution. The cluster formation can be characterized by means of equilibrium thermodynamics, applying a multiple-binding model, which allows for structural preformation. Stable clusters are the relevant species in calcium carbonate nucleation. Such mechanisms may also be important for the crystallization of other minerals.

  17. Continuous generation of delayed light

    Science.gov (United States)

    Smartsev, Slava; Eger, David; Davidson, Nir; Firstenberg, Ofer

    2017-11-01

    We use a four-wave mixing process to read-out light from atomic coherence which is continuously written. The light is continuously generated after an effective delay, allowing the atomic coherence to evolve during the process. Contrary to slow-light delay, which depends on the medium optical depth, here the generation delay is determined solely by the intensive properties of the system, approaching the atomic coherence lifetime at the weak driving limit. The atomic evolution during the generation delay is further manifested in the spatial profile of the generated light due to atomic diffusion. Continuous generation of light with a long intrinsic delay can replace discrete write–read procedures when the atomic evolution is the subject of interest.

  18. Delayed radiation neuropathy

    Energy Technology Data Exchange (ETDEWEB)

    Nagashima, T.; Miyamoto, K.; Beppu, H.; Hirose, K.; Yamada, K. (Tokyo Metropolitan Neurological Hospital (Japan))

    1981-07-01

    A case of cervical plexus neuropathy was reported in association with chronic radio-dermatitis, myxedema with thyroid adenoma and epiglottic tumor. A 38-year-old man has noticed muscle weakness and wasting of the right shoulder girdle since age 33. A detailed history taking revealed a previous irradiation to the neck because of the cervical lymphadenopathy at age 10 (X-ray 3,000 rads), keroid skin change at age 19, obesity and edema since 26, and hoarseness at 34. Laryngoscopic examination revealed a tumor on the right vocal cord, diagnosed as benign papilloma by histological study. In addition, there were chronic radio-dermatitis around the neck, primary hypothyroidism with a benign functioning adenoma on the right lobe of the thyroid, the right phrenic nerve palsy and the right recurrent nerve palsy. All these lesions were considered to be the late sequellae of radiation to the neck in childhood. Other neurological signs were weakness and amyotrophy of the right shoulder girdle with patchy sensory loss, and areflexia of the right arm. Gross power was fairly well preserved in the right hand. EMG showed neurogenic changes in the tested muscles, suggesting a peripheral nerve lesion. Nerve conduction velocities were normal. No abnormal findings were revealed by myelography and spinal CT. The neurological findings of the patient were compatible with the diagnosis of middle cervical plexus palsy apparently due to late radiation effect. In the literature eight cases of post-radiation neuropathy with a long latency have been reported. The present case with the longest latency after the radiation should be included in the series of the reported cases of ''delayed radiation neuropathy.'' (author).

  19. Neocortical GABA release at high intracellular sodium and low extracellular calcium: an anti-seizure mechanism.

    Science.gov (United States)

    Rassner, Michael P; Moser, Andreas; Follo, Marie; Joseph, Kevin; van Velthoven-Wurster, Vera; Feuerstein, Thomas J

    2016-04-01

    In epilepsy, the GABA and glutamate balance may be disrupted and a transient decrease in extracellular calcium occurs before and during a seizure. Flow Cytometry based fluorescence activated particle sorting experiments quantified synaptosomes from human neocortical tissue, from both epileptic and non-epileptic patients (27.7% vs. 36.9% GABAergic synaptosomes, respectively). Transporter-mediated release of GABA in human and rat neocortical synaptosomes was measured using the superfusion technique for the measurement of endogenous GABA. GABA release was evoked by either a sodium channel activator or a sodium/potassium-ATPase inhibitor when exocytosis was possible or prevented, and when the sodium/calcium exchanger was active or inhibited. The transporter-mediated release of GABA is because of elevated intracellular sodium. A reduction in the extracellular calcium increased this release (in both non-epileptic and epileptic, except Rasmussen encephalitis, synaptosomes). The inverse was seen during calcium doubling. In humans, GABA release was not affected by exocytosis inhibition, that is, it was solely transporter-mediated. However, in rat synaptosomes, an increase in GABA release at zero calcium was only exhibited when the exocytosis was prevented. The absence of calcium amplified the sodium/calcium exchanger activity, leading to elevated intracellular sodium, which, together with the stimulation-evoked intracellular sodium increment, enhanced GABA transporter reversal. Sodium/calcium exchange inhibitors diminished GABA release. Thus, an important seizure-induced extracellular calcium reduction might trigger a transporter- and sodium/calcium exchanger-related anti-seizure mechanism by augmenting transporter-mediated GABA release, a mechanism absent in rats. Uniquely, the additional increase in GABA release because of calcium-withdrawal dwindled during the course of illness in Rasmussen encephalitis. Seizures cause high Na(+) influx through action potentials. A

  20. Calcium-activated chloride channels in the apical region of mouse vomeronasal sensory neurons.

    Science.gov (United States)

    Dibattista, Michele; Amjad, Asma; Maurya, Devendra Kumar; Sagheddu, Claudia; Montani, Giorgia; Tirindelli, Roberto; Menini, Anna

    2012-07-01

    The rodent vomeronasal organ plays a crucial role in several social behaviors. Detection of pheromones or other emitted signaling molecules occurs in the dendritic microvilli of vomeronasal sensory neurons, where the binding of molecules to vomeronasal receptors leads to the influx of sodium and calcium ions mainly through the transient receptor potential canonical 2 (TRPC2) channel. To investigate the physiological role played by the increase in intracellular calcium concentration in the apical region of these neurons, we produced localized, rapid, and reproducible increases in calcium concentration with flash photolysis of caged calcium and measured calcium-activated currents with the whole cell voltage-clamp technique. On average, a large inward calcium-activated current of -261 pA was measured at -50 mV, rising with a time constant of 13 ms. Ion substitution experiments showed that this current is anion selective. Moreover, the chloride channel blockers niflumic acid and 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid partially inhibited the calcium-activated current. These results directly demonstrate that a large chloride current can be activated by calcium in the apical region of mouse vomeronasal sensory neurons. Furthermore, we showed by immunohistochemistry that the calcium-activated chloride channels TMEM16A/anoctamin1 and TMEM16B/anoctamin2 are present in the apical layer of the vomeronasal epithelium, where they largely colocalize with the TRPC2 transduction channel. Immunocytochemistry on isolated vomeronasal sensory neurons showed that TMEM16A and TMEM16B coexpress in the neuronal microvilli. Therefore, we conclude that microvilli of mouse vomeronasal sensory neurons have a high density of calcium-activated chloride channels that may play an important role in vomeronasal transduction.

  1. Calcium homeostasis is altered in skeletal muscle of spontaneously hypertensive rats: cytofluorimetric and gene expression analysis.

    Science.gov (United States)

    Liantonio, Antonella; Camerino, Giulia M; Scaramuzzi, Antonia; Cannone, Maria; Pierno, Sabata; De Bellis, Michela; Conte, Elena; Fraysse, Bodvael; Tricarico, Domenico; Conte Camerino, Diana

    2014-10-01

    Hypertension is often associated with skeletal muscle pathological conditions related to function and metabolism. The mechanisms underlying the development of these pathological conditions remain undefined. Because calcium homeostasis is a biomarker of muscle function, we assessed whether it is altered in hypertensive muscles. We measured resting intracellular calcium and store-operated calcium entry (SOCE) in fast- and slow-twitch muscle fibers from normotensive Wistar-Kyoto rats and spontaneously hypertensive rats (SHRs) by cytofluorimetric technique and determined the expression of SOCE gene machinery by real-time PCR. Hypertension caused a phenotype-dependent dysregulation of calcium homeostasis; the resting intracellular calcium of extensor digitorum longus and soleus muscles of SHRs were differently altered with respect to the related muscle of normotensive animals. In addition, soleus muscles of SHR showed reduced activity of the sarcoplasmic reticulum and decreased sarcolemmal calcium permeability at rest and after SOCE activation. Accordingly, we found an alteration of the expression levels of some SOCE components, such as stromal interaction molecule 1, calcium release-activated calcium modulator 1, and transient receptor potential canonical 1. The hypertension-induced alterations of calcium homeostasis in the soleus muscle of SHRs occurred with changes of some functional outcomes as excitability and resting chloride conductance. We provide suitable targets for therapeutic interventions aimed at counterbalancing muscle performance decline in hypertension, and propose the reported calcium-dependent parameters as indexes to predict how the antihypertensive drugs could influence muscle function. Copyright © 2014 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

  2. Nuclear Calcium Signaling Induces Expression of the Synaptic Organizers Lrrtm1 and Lrrtm2*

    Science.gov (United States)

    Hayer, Stefanie N.; Bading, Hilmar

    2015-01-01

    Calcium transients in the cell nucleus evoked by synaptic activity in hippocampal neurons function as a signaling end point in synapse-to-nucleus communication. As an important regulator of neuronal gene expression, nuclear calcium is involved in the conversion of synaptic stimuli into functional and structural changes of neurons. Here we identify two synaptic organizers, Lrrtm1 and Lrrtm2, as targets of nuclear calcium signaling. Expression of both Lrrtm1 and Lrrtm2 increased in a synaptic NMDA receptor- and nuclear calcium-dependent manner in hippocampal neurons within 2–4 h after the induction of action potential bursting. Induction of Lrrtm1 and Lrrtm2 occurred independently of the need for new protein synthesis and required calcium/calmodulin-dependent protein kinases and the nuclear calcium signaling target CREB-binding protein. Analysis of reporter gene constructs revealed a functional cAMP response element in the proximal promoter of Lrrtm2, indicating that at least Lrrtm2 is regulated by the classical nuclear Ca2+/calmodulin-dependent protein kinase IV-CREB/CREB-binding protein pathway. These results suggest that one mechanism by which nuclear calcium signaling controls neuronal network function is by regulating the expression of Lrrtm1 and Lrrtm2. PMID:25527504

  3. Nuclear calcium signaling induces expression of the synaptic organizers Lrrtm1 and Lrrtm2.

    Science.gov (United States)

    Hayer, Stefanie N; Bading, Hilmar

    2015-02-27

    Calcium transients in the cell nucleus evoked by synaptic activity in hippocampal neurons function as a signaling end point in synapse-to-nucleus communication. As an important regulator of neuronal gene expression, nuclear calcium is involved in the conversion of synaptic stimuli into functional and structural changes of neurons. Here we identify two synaptic organizers, Lrrtm1 and Lrrtm2, as targets of nuclear calcium signaling. Expression of both Lrrtm1 and Lrrtm2 increased in a synaptic NMDA receptor- and nuclear calcium-dependent manner in hippocampal neurons within 2-4 h after the induction of action potential bursting. Induction of Lrrtm1 and Lrrtm2 occurred independently of the need for new protein synthesis and required calcium/calmodulin-dependent protein kinases and the nuclear calcium signaling target CREB-binding protein. Analysis of reporter gene constructs revealed a functional cAMP response element in the proximal promoter of Lrrtm2, indicating that at least Lrrtm2 is regulated by the classical nuclear Ca(2+)/calmodulin-dependent protein kinase IV-CREB/CREB-binding protein pathway. These results suggest that one mechanism by which nuclear calcium signaling controls neuronal network function is by regulating the expression of Lrrtm1 and Lrrtm2. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  4. Delay of Gratification and Delay Discounting: A Unifying Feedback Model of Delay-Related Impulsive Behavior

    Science.gov (United States)

    Reynolds, Brady; Schiffbauer, Ryan

    2005-01-01

    Delay of Gratification (DG) and Delay Discounting (DD) represent two indices of impulsive behavior often treated as though they represent equivalent or the same underlying processes. However, there are key differences between DG and DD procedures, and between certain research findings with each procedure, that suggest they are not equivalent. In…

  5. Single-Event-Hardened All-Digital Delay Generator for FPGA-Based Implementation of a TDC-based readout electronics

    Science.gov (United States)

    Balaji, S.; Ramasamy, S.

    2017-09-01

    This paper addresses the single-events effects on an all-digital delay generator and also investigates the propagation and impact of soft errors in the all-digital delay generator caused by the single-event transients to the time-to-digital converters. The all-digital delay generator is implemented using an array of all-digital delay-locked loops with error correction circuit for improved single-event transients resilience and uses the time interpolation technique for achieving 5 ps sub-gate delay resolution. The effectiveness of the mitigation of single-event upsets and the robustness of the architecture is demonstrated through the simulations in 90 nm CMOS technology at linear energy transfer up to 100 MeVṡcm2/mg. The portability of the mitigation technique is validated by the results obtained through an FPGA implementation of the all-digital delay generator.

  6. Transient or permanent fisheye views

    DEFF Research Database (Denmark)

    Jakobsen, Mikkel Rønne; Hornbæk, Kasper

    2012-01-01

    programming environment. Fourteen participants performed varied tasks involving navigation and understanding of source code. Participants used the three interfaces for between four and six hours in all. Time and accuracy measures were inconclusive, but subjective data showed a preference for the permanent......, about the benefits and limitations of transient visualizations. We describe an experiment that compares the usability of a fisheye view that participants could call up temporarily, a permanent fisheye view, and a linear view: all interfaces gave access to source code in the editor of a widespread...

  7. Transient simulation of radiating flows

    Energy Technology Data Exchange (ETDEWEB)

    Selcuk, Nevin [Department of Chemical Engineering, Middle East Technical University, Inonu Bulvari, 06531 Ankara (Turkey)]. E-mail: selcuk@metu.edu.tr; Bilge Uygur, A. [Department of Chemical Engineering, Middle East Technical University, Inonu Bulvari, 06531 Ankara (Turkey); Ayranci, Isil [Department of Chemical Engineering, Middle East Technical University, Inonu Bulvari, 06531 Ankara (Turkey); Tarhan, Tanil [Department of Chemical Engineering, Middle East Technical University, Inonu Bulvari, 06531 Ankara (Turkey)

    2005-06-15

    Time-dependent Navier-Stokes equations are solved in conjunction with the radiative transfer equation by coupling a previously developed direct numerical simulation-based computational fluid dynamics code to an existing radiation code, both based on the method of lines approach. The temperature profiles predicted by the coupled code are validated against steady-state solutions available in the literature for laminar, axisymmetric, hydrodynamically developed flow of a gray, absorbing, emitting fluid in a heated pipe. Favorable comparisons show the predictive accuracy and reliability of the coupling strategy employed. Transient solutions for a more realistic heat transfer problem are also demonstrated for simultaneous hydrodynamic and thermal development.

  8. Calcium orthophosphate coatings on magnesium and its biodegradable alloys.

    Science.gov (United States)

    Dorozhkin, Sergey V

    2014-07-01

    Biodegradable metals have been suggested as revolutionary biomaterials for bone-grafting therapies. Of these metals, magnesium (Mg) and its biodegradable alloys appear to be particularly attractive candidates due to their non-toxicity and as their mechanical properties match those of bones better than other metals do. Being light, biocompatible and biodegradable, Mg-based metallic implants have several advantages over other implantable metals currently in use, such as eliminating both the effects of stress shielding and the requirement of a second surgery for implant removal. Unfortunately, the fast degradation rates of Mg and its biodegradable alloys in the aggressive physiological environment impose limitations on their clinical applications. This necessitates development of implants with controlled degradation rates to match the kinetics of bone healing. Application of protective but biocompatible and biodegradable coatings able to delay the onset of Mg corrosion appears to be a reasonable solution. Since calcium orthophosphates are well tolerated by living organisms, they appear to be the excellent candidates for such coatings. Nevertheless, both the high chemical reactivity and the low melting point of Mg require specific parameters for successful deposition of calcium orthophosphate coatings. This review provides an overview of current coating techniques used for deposition of calcium orthophosphates on Mg and its biodegradable alloys. The literature analysis revealed that in all cases the calcium orthophosphate protective coatings both increased the corrosion resistance of Mg-based metallic biomaterials and improved their surface biocompatibility. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  9. Transient receptor potential (TRP gene superfamily encoding cation channels

    Directory of Open Access Journals (Sweden)

    Pan Zan

    2011-01-01

    Full Text Available Abstract Transient receptor potential (TRP non-selective cation channels constitute a superfamily, which contains 28 different genes. In mammals, this superfamily is divided into six subfamilies based on differences in amino acid sequence homology between the different gene products. Proteins within a subfamily aggregate to form heteromeric or homomeric tetrameric configurations. These different groupings have very variable permeability ratios for calcium versus sodium ions. TRP expression is widely distributed in neuronal tissues, as well as a host of other tissues, including epithelial and endothelial cells. They are activated by environmental stresses that include tissue injury, changes in temperature, pH and osmolarity, as well as volatile chemicals, cytokines and plant compounds. Their activation induces, via intracellular calcium signalling, a host of responses, including stimulation of cell proliferation, migration, regulatory volume behaviour and the release of a host of cytokines. Their activation is greatly potentiated by phospholipase C (PLC activation mediated by coupled GTP-binding proteins and tyrosine receptors. In addition to their importance in maintaining tissue homeostasis, some of these responses may involve various underlying diseases. Given the wealth of literature describing the multiple roles of TRP in physiology in a very wide range of different mammalian tissues, this review limits itself to the literature describing the multiple roles of TRP channels in different ocular tissues. Accordingly, their importance to the corneal, trabecular meshwork, lens, ciliary muscle, retinal, microglial and retinal pigment epithelial physiology and pathology is reviewed.

  10. Calcium metabolism & hypercalcemia in adults.

    Science.gov (United States)

    Lumachi, F; Motta, R; Cecchin, D; Ave, S; Camozzi, V; Basso, S M M; Luisetto, G

    2011-01-01

    Calcium is essential for many metabolic process, including nerve function, muscle contraction, and blood clotting. The metabolic pathways that contribute to maintain serum calcium levels are bone remodeling processes, intestinal absorption and secretion, and renal handling, but hypercalcemia occurs when at least 2 of these 3 metabolic pathways are altered. Calcium metabolism mainly depends on the activity of parathyroid hormone (PTH). Its secretion is strictly controlled by the ionized serum calcium levels through a negative feed-back, which is achieved by the activation of calcium-sensing receptors (CaSRs) mainly expressed on the surface of the parathyroid cells. The PTH receptor in bone and kidney is now referred as PTHR1. The balance of PTH, calcitonin, and vitamin D has long been considered the main regulator of calcium metabolism, but the function of other actors, such as fibroblast growth factor-23 (FGF-23), Klotho, and TPRV5 should be considered. Primary hyperparathyroidism and malignancy are the most common causes of hypercalcemia, accounting for more than 90% of cases. Uncontrolled hypercalcemia may cause renal impairment, both temporary (alteration of renal tubular function) and progressive (relapsing nephrolithiasis), leading to a progressive loss of renal function, as well as severe bone diseases, and heart damages. Advances in the understanding of all actors of calcium homeostasis will be crucial, having several practical consequences in the treatment and prevention of hypercalcemia. This would allow to move from a support therapy, sometimes ineffective, to a specific and addressed therapy, especially in patients with chronic hypercalcemic conditions unsuitable for surgery.

  11. Evodiamine Induces Transient Receptor Potential Vanilloid-1-Mediated Protective Autophagy in U87-MG Astrocytes

    Directory of Open Access Journals (Sweden)

    Ann-Jeng Liu

    2013-01-01

    Full Text Available Cerebral ischemia is a leading cause of mortality and morbidity worldwide, which results in cognitive and motor dysfunction, neurodegenerative diseases, and death. Evodiamine (Evo is extracted from Evodia rutaecarpa Bentham, a plant widely used in Chinese herbal medicine, which possesses variable biological abilities, such as anticancer, anti-inflammation, antiobesity, anti-Alzheimer’s disease, antimetastatic, antianoxic, and antinociceptive functions. But the effect of Evo on ischemic stroke is unclear. Increasing data suggest that activation of autophagy, an adaptive response to environmental stresses, could protect neurons from ischemia-induced cell death. In this study, we found that Evo induced autophagy in U87-MG astrocytes. A scavenger of extracellular calcium and an antagonist of transient receptor potential vanilloid-1 (TRPV-1 decreased the percentage of autophagy accompanied by an increase in apoptosis, suggesting that Evo may induce calcium-mediated protective autophagy resulting from an influx of extracellular calcium. The same phenomena were also confirmed by a small interfering RNA technique to knock down the expression of TRPV1. Finally, Evo-induced c-Jun N-terminal kinases (JNK activation was reduced by a TRPV1 antagonist, indicating that Evo-induced autophagy may occur through a calcium/c-Jun N-terminal kinase (JNK pathway. Collectively, Evo induced an influx of extracellular calcium, which led to JNK-mediated protective autophagy, and this provides a new option for ischemic stroke treatment.

  12. Evodiamine Induces Transient Receptor Potential Vanilloid-1-Mediated Protective Autophagy in U87-MG Astrocytes

    Science.gov (United States)

    Liu, Ann-Jeng; Wang, Sheng-Hao; Hou, Sz-Ying; Chiu, Wen-Ta; Hsiao, Sheng-Huang; Chen, Thay-Hsiung

    2013-01-01

    Cerebral ischemia is a leading cause of mortality and morbidity worldwide, which results in cognitive and motor dysfunction, neurodegenerative diseases, and death. Evodiamine (Evo) is extracted from Evodia rutaecarpa Bentham, a plant widely used in Chinese herbal medicine, which possesses variable biological abilities, such as anticancer, anti-inflammation, antiobesity, anti-Alzheimer's disease, antimetastatic, antianoxic, and antinociceptive functions. But the effect of Evo on ischemic stroke is unclear. Increasing data suggest that activation of autophagy, an adaptive response to environmental stresses, could protect neurons from ischemia-induced cell death. In this study, we found that Evo induced autophagy in U87-MG astrocytes. A scavenger of extracellular calcium and an antagonist of transient receptor potential vanilloid-1 (TRPV-1) decreased the percentage of autophagy accompanied by an increase in apoptosis, suggesting that Evo may induce calcium-mediated protective autophagy resulting from an influx of extracellular calcium. The same phenomena were also confirmed by a small interfering RNA technique to knock down the expression of TRPV1. Finally, Evo-induced c-Jun N-terminal kinases (JNK) activation was reduced by a TRPV1 antagonist, indicating that Evo-induced autophagy may occur through a calcium/c-Jun N-terminal kinase (JNK) pathway. Collectively, Evo induced an influx of extracellular calcium, which led to JNK-mediated protective autophagy, and this provides a new option for ischemic stroke treatment. PMID:24454492

  13. Prohexadione-calcium changes morphological and physical traits in strawberry plants and preconditions transplants to water stress

    NARCIS (Netherlands)

    Reekie, J.Y.; Struik, P.C.; Hicklenton, P.R.; Duval, J.R.

    2007-01-01

    Prohexadione-calcium (ProCa) applied as foliar spray, increases root to shoot ratio and reduces specific leaf area (SLA) in strawberry plants ( Fragaria × ananassa Duch.). These effects may help treated plants to survive a transplant shock. Under mild water stress, ProCa caused a transient reduction

  14. Time Delay in Molecular Photoionization

    CERN Document Server

    Hockett, P; Villeneuve, D M; Corkum, P B

    2015-01-01

    Time-delays in the photoionization of molecules are investigated. As compared to atomic ionization, the time-delays expected from molecular ionization present a much richer phenomenon, with a strong spatial dependence due to the anisotropic nature of the molecular scattering potential. We investigate this from a scattering theory perspective, and make use of molecular photoionization calculations to examine this effect in representative homonuclear and hetronuclear diatomic molecules, nitrogen and carbon monoxide. We present energy and angle-resolved maps of the Wigner delay time for single-photon valence ionization, and discuss the possibilities for experimental measurements.

  15. Transient global amnesia: current perspectives

    Directory of Open Access Journals (Sweden)

    Spiegel DR

    2017-10-01

    Full Text Available David R Spiegel, Justin Smith, Ryan R Wade, Nithya Cherukuru, Aneel Ursani, Yuliya Dobruskina, Taylor Crist, Robert F Busch, Rahim M Dhanani, Nicholas Dreyer Department of Psychiatry and Behavioral Sciences, Eastern Virginia Medical School, Norfolk, VA, USA Abstract: Transient global amnesia (TGA is a clinical syndrome characterized by the sudden onset of an extraordinarily large reduction of anterograde and a somewhat milder reduction of retrograde episodic long-term memory. Additionally, executive functions are described as diminished. Although it is suggested that various factors, such as migraine, focal ischemia, venous flow abnormalities, and epileptic phenomena, are involved in the pathophysiology and differential diagnosis of TGA, the factors triggering the emergence of these lesions are still elusive. Recent data suggest that the vulnerability of CA1 neurons to metabolic stress plays a pivotal part in the pathophysiological cascade, leading to an impairment of hippocampal function during TGA. In this review, we discuss clinical aspects, new imaging findings, and recent clinical–epidemiological data with regard to the phenotype, functional anatomy, and putative cellular mechanisms of TGA. Keywords: transient global amnesia, vascular, migraines, psychiatric

  16. Transient Science from Diverse Surveys

    Science.gov (United States)

    Mahabal, A.; Crichton, D.; Djorgovski, S. G.; Donalek, C.; Drake, A.; Graham, M.; Law, E.

    2016-12-01

    Over the last several years we have moved closer to being able to make digital movies of the non-static sky with wide-field synoptic telescopes operating at a variety of depths, resolutions, and wavelengths. For optimal combined use of these datasets, it is crucial that they speak and understand the same language and are thus interoperable. Initial steps towards such interoperability (e.g. the footprint service) were taken during the two five-year Virtual Observatory projects viz. National Virtual Observatory (NVO), and later Virtual Astronomical Observatory (VAO). Now with far bigger datasets and in an era of resource excess thanks to the cloud-based workflows, we show how the movement of data and of resources is required - rather than just one or the other - to combine diverse datasets for applications such as real-time astronomical transient characterization. Taking the specific example of ElectroMagnetic (EM) follow-up of Gravitational Wave events and EM transients (such as CRTS but also other optical and non-optical surveys), we discuss the requirements for rapid and flexible response. We show how the same methodology is applicable to Earth Science data with its datasets differing in spatial and temporal resolution as well as differing time-spans.

  17. Transient trimethylaminuria related to menstruation

    Science.gov (United States)

    Shimizu, Makiko; Cashman, John R; Yamazaki, Hiroshi

    2007-01-01

    Background Trimethylaminuria, or fish odor syndrome, includes a transient or mild malodor caused by an excessive amount of malodorous trimethylamine as a result of body secretions. Herein, we describe data to support the proposal that menses can be an additional factor causing transient trimethylaminuria in self-reported subjects suffering from malodor and even in healthy women harboring functionally active flavin-containing monooxygenase 3 (FMO3). Methods FMO3 metabolic capacity (conversion of trimethylamine to trimethylamine N-oxide) was defined as the urinary ratio of trimethylamine N-oxide to total trimethylamine. Results Self-reported Case (A) that was homozygous for inactive Arg500stop FMO3, showed decreased metabolic capacity of FMO3 (i.e., ~10% the unaffected metabolic capacity) during 120 days of observation. For Case (B) that was homozygous for common [Glu158Lys; Glu308Gly] FMO3 polymorphisms, metabolic capacity of FMO3 was almost ~90%, except for a few days surrounding menstruation showing 90%) metabolic capacity, however, on days around menstruation the FMO3 metabolic capacity was decreased to ~60–70%. Conclusion Together, these results indicate that abnormal FMO3 capacity is caused by menstruation particularly in the presence, in homozygous form, of mild genetic variants such as [Glu158Lys; Glu308Gly] that cause a reduced FMO3 function. PMID:17257434

  18. Transient electromagnetic sounding for groundwater

    Science.gov (United States)

    Fitterman, David V.; Stewart, Mark T.

    1986-01-01

    The feasibility of using the transient electromagnetic sounding (TS or TDEM) method for groundwater exploration can be studied by means of numerical models. As examples of its applicability to groundwater exploration, we study four groundwater exploration problems: (1) mapping of alluvial fill and gravel zones over bedrock; (2) mapping of sand and gravel lenses in till; (3) detection of salt or brackish water interfaces in freshwater aquifers; and (4) determination of hydrostratigraphy. These groundwater problems require determination of the depth to bedrock; location of resistive, high‐porosity zones associated with fresh water; determination of formation resistivity to assess water quality; and determination of lithology and geometry, respectively. The TS method is best suited for locating conductive targets, and has very good vertical resolution. Unlike other sounding techniques where the receiver‐transmitter array must be expanded to sound more deeply, the depth of investigation for the TS method is a function of the length of time the transient is recorded. Present equipment limitations require that exploration targets with resistivities of 50 Ω ⋅ m or more be at least 50 m deep to determine their resistivity. The maximum depth of exploration is controlled by the geoelectrical section and background electromagnetic (EM) noise. For a particular exploration problem, numerical studies are recommended to determine if the target is detectable.

  19. Calcium and Calcium Supplements: Achieving the Right Balance

    Science.gov (United States)

    ... Duyff RL. American Dietetic Association Complete Food and Nutrition Guide. 4th ed. Hoboken, N.J.: John Wiley & Sons; 2012:140. Rosen HN. Calcium and vitamin D supplementation in osteoporosis. http://www.uptodate.com/home/index. ...

  20. Calcium carbonate and calcium sulfate in Martian meteorite EETA79001

    Science.gov (United States)

    Gooding, J. L.; Wentworth, S. J.

    1987-01-01

    Chips of glassy Lithology C of EETA79001 were studied by scanning electron microscopy and energy dispersive X-ray spectroscopy to determine the mineralogy and petrogenesis of the glass that was shown by others to contain trapped Mars-like gases. Calcium carbonite was identified as massive to acicular crystals for which Ca, C, and O were the major elements. Calcium sulfate was identified as prismatic-acicular crystals with Ca and S as the major elements.

  1. Effects of thymol on calcium and potassium currents in canine and human ventricular cardiomyocytes

    Science.gov (United States)

    Magyar, János; Szentandrássy, Norbert; Bányász, Tamás; Fülöp, László; Varró, András; Nánási, Péter P

    2002-01-01

    Concentration-dependent effects of thymol (1–1000 μM) was studied on action potential configuration and ionic currents in isolated canine ventricular cardiomyocytes using conventional microelectrode and patch clamp techniques.Low concentration of thymol (10 μM) removed the notch of the action potential, whereas high concentrations (100 μM or higher) caused an additional shortening of action potential duration accompanied by progressive depression of plateau and reduction of Vmax.In the canine cells L-type Ca current (ICa) was decreased by thymol in a concentration-dependent manner (EC50: 158±7 μM, Hill coeff.: 2.96±0.43). In addition, thymol (50–250 μM) accelerated the inactivation of ICa, increased the time constant of recovery from inactivation, shifted the steady-state inactivation curve of ICa leftwards, but voltage dependence of activation remained unaltered. Qualitatively similar results were obtained with thymol in ventricular myocytes isolated from healthy human hearts.Thymol displayed concentration-dependent suppressive effects on potassium currents: the transient outward current, Ito (EC50: 60.6±11.4 μM, Hill coeff.: 1.03±0.11), the rapid component of the delayed rectifier, IKr (EC50: 63.4±6.1 μM, Hill coeff.: 1.29±0.15), and the slow component of the delayed rectifier, IKs (EC50: 202±11 μM, Hill coeff.: 0.72±0.14), however, K channel kinetics were not much altered by thymol. These effects on Ca and K currents developed rapidly (within 0.5 min) and were readily reversible.In conclusion, thymol suppressed cardiac ionic channels in a concentration-dependent manner, however, both drug-sensitivities as well as the mechanism of action seems to be different when blocking calcium and potassium channels. PMID:12010783

  2. DELAYED PUBERTY: A LATE DIAGNOSIS

    Directory of Open Access Journals (Sweden)

    Helena Ferreira

    2017-04-01

    Discussion/Conclusion: We aimed to aware Crohn’s disease as one of the causes of pubertal and growth delay, highlighting the need for early diagnosis and therapy, in order to reach a favorable pubertal development.

  3. Delays and networked control systems

    CERN Document Server

    Hetel, Laurentiu; Daafouz, Jamal; Johansson, Karl

    2016-01-01

    This edited monograph includes state-of-the-art contributions on continuous time dynamical networks with delays. The book is divided into four parts. The first part presents tools and methods for the analysis of time-delay systems with a particular attention on control problems of large scale or infinite-dimensional systems with delays. The second part of the book is dedicated to the use of time-delay models for the analysis and design of Networked Control Systems. The third part of the book focuses on the analysis and design of systems with asynchronous sampling intervals which occur in Networked Control Systems. The last part of the book exposes several contributions dealing with the design of cooperative control and observation laws for networked control systems. The target audience primarily comprises researchers and experts in the field of control theory, but the book may also be beneficial for graduate students. .

  4. Parental Discipline and Delayed Gratification

    Science.gov (United States)

    Weller, Leonard; Berkowitz, Edith

    1975-01-01

    It was hypothesized that children brought up under coercive power would be more likely to exhibit immediate gratification, whereas children brought up under noncoercive power would be more likely to delay gratification. The hypothesis was confirmed. (Author)

  5. Fractional variational principles with delay

    Science.gov (United States)

    Baleanu, Dumitru; Maaraba Abdeljawad, Thabet; Jarad, Fahd

    2008-08-01

    The fractional variational principles within Riemann-Liouville fractional derivatives in the presence of delay are analyzed. The corresponding Euler-Lagrange equations are obtained and one example is analyzed in detail.

  6. Fractional variational principles with delay

    Energy Technology Data Exchange (ETDEWEB)

    Baleanu, Dumitru; Abdeljawad, Thabet Maaraba; Jarad, Fahd [Department of Mathematics and Computer Sciences, Faculty of Arts and Sciences, Cankaya University, 06530 Ankara (Turkey)], E-mail: dumitru@cankaya.edu.tr, E-mail: baleanu@venus.nipne.ro

    2008-08-08

    The fractional variational principles within Riemann-Liouville fractional derivatives in the presence of delay are analyzed. The corresponding Euler-Lagrange equations are obtained and one example is analyzed in detail.

  7. EAMJ Delayed April 10.indd

    African Journals Online (AJOL)

    2010-04-04

    Apr 4, 2010 ... INTRODUCTION. Breast cancer remains a leading cause of death of ... ABSTRACT. Objective: To determine the extent and nature of delayed presentation of patients .... symptomatic breast cancer: a systematic review. Lancet.

  8. Reciprocal Interaction of Dendrite Geometry and Nuclear Calcium-VEGFD Signaling Gates Memory Consolidation and Extinction.

    Science.gov (United States)

    Hemstedt, Thekla J; Bengtson, C Peter; Ramírez, Omar; Oliveira, Ana M M; Bading, Hilmar

    2017-07-19

    Nuclear calcium is an important signaling end point in synaptic excitation-transcription coupling that is critical for long-term neuroadaptations. Here, we show that nuclear calcium acting via a target gene, VEGFD, is required for hippocampus-dependent fear memory consolidation and extinction in mice. Nuclear calcium-VEGFD signaling upholds the structural integrity and complexity of the dendritic arbor of CA1 neurons that renders those cells permissive for the efficient generation of synaptic input-evoked nuclear calcium transients driving the expression of plasticity-related genes. Therefore, the gating of memory functions rests on the reciprocally reinforcing maintenance of an intact dendrite geometry and a functional synapse-to-nucleus communication axis. In psychiatric and neurodegenerative disorders, therapeutic application of VEGFD may help to stabilize dendritic structures and network connectivity, which may prevent cognitive decline and could boost the efficacy of extinction-based exposure therapies. SIGNIFICANCE STATEMENT This study uncovers a reciprocal relationship between dendrite geometry, the ability to generate nuclear calcium transients in response to synaptic inputs, and the subsequent induction of expression of plasticity-related and dendritic structure-preserving genes. Insufficient nuclear calcium signaling in CA1 hippocampal neurons and, consequently, reduced expression of the nuclear calcium target gene VEGFD, a dendrite maintenance factor, leads to reduced-complexity basal dendrites of CA1 neurons, which severely compromises the animals' consolidation of both memory and extinction memory. The structure-protective function of VEGFD may prove beneficial in psychiatric disorders as well as neurodegenerative and aging-related conditions that are associated with loss of neuronal structures, dysfunctional excitation-transcription coupling, and cognitive decline. Copyright © 2017 the authors 0270-6474/17/376946-10$15.00/0.

  9. What drives transient behavior in complex systems?

    Science.gov (United States)

    Grela, Jacek

    2017-08-01

    We study transient behavior in the dynamics of complex systems described by a set of nonlinear ordinary differential equations. Destabilizing nature of transient trajectories is discussed and its connection with the eigenvalue-based linearization procedure. The complexity is realized as a random matrix drawn from a modified May-Wigner model. Based on the initial response of the system, we identify a novel stable-transient regime. We calculate exact abundances of typical and extreme transient trajectories finding both Gaussian and Tracy-Widom distributions known in extreme value statistics. We identify degrees of freedom driving transient behavior as connected to the eigenvectors and encoded in a nonorthogonality matrix T0. We accordingly extend the May-Wigner model to contain a phase with typical transient trajectories present. An exact norm of the trajectory is obtained in the vanishing T0 limit where it describes a normal matrix.

  10. Systematics in delayed neutron yields

    Energy Technology Data Exchange (ETDEWEB)

    Ohsawa, Takaaki [Kinki Univ., Higashi-Osaka, Osaka (Japan). Atomic Energy Research Inst.

    1998-03-01

    An attempt was made to reproduce the systematic trend observed in the delayed neutron yields for actinides on the basis of the five-Gaussian representation of the fission yield together with available data sets for delayed neutron emission probability. It was found that systematic decrease in DNY for heavier actinides is mainly due to decrease of fission yields of precursors in the lighter side of the light fragment region. (author)

  11. Measuring information-transfer delays.

    Directory of Open Access Journals (Sweden)

    Michael Wibral

    Full Text Available In complex networks such as gene networks, traffic systems or brain circuits it is important to understand how long it takes for the different parts of the network to effectively influence one another. In the brain, for example, axonal delays between brain areas can amount to several tens of milliseconds, adding an intrinsic component to any timing-based processing of information. Inferring neural interaction delays is thus needed to interpret the information transfer revealed by any analysis of directed interactions across brain structures. However, a robust estimation of interaction delays from neural activity faces several challenges if modeling assumptions on interaction mechanisms are wrong or cannot be made. Here, we propose a robust estimator for neuronal interaction delays rooted in an information-theoretic framework, which allows a model-free exploration of interactions. In particular, we extend transfer entropy to account for delayed source-target interactions, while crucially retaining the conditioning on the embedded target state at the immediately previous time step. We prove that this particular extension is indeed guaranteed to identify interaction delays between two coupled systems and is the only relevant option in keeping with Wiener's principle of causality. We demonstrate the performance of our approach in detecting interaction delays on finite data by numerical simulations of stochastic and deterministic processes, as well as on local field potential recordings. We also show the ability of the extended transfer entropy to detect the presence of multiple delays, as well as feedback loops. While evaluated on neuroscience data, we expect the estimator to be useful in other fields dealing with network dynamics.

  12. 21 CFR 184.1187 - Calcium alginate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium alginate. 184.1187 Section 184.1187 Food... Specific Substances Affirmed as GRAS § 184.1187 Calcium alginate. (a) Calcium alginate (CAS Reg. No. 9005.... Calcium alginate is prepared by the neutralization of purified alginic acid with appropriate pH control...

  13. Extracellular and Intracellular Regulation of Calcium Homeostasis

    Directory of Open Access Journals (Sweden)

    Felix Bronner

    2001-01-01

    Full Text Available An organism with an internal skeleton must accumulate calcium while maintaining body fluids at a well-regulated, constant calcium concentration. Neither calcium absorption nor excretion plays a significant regulatory role. Instead, isoionic calcium uptake and release by bone surfaces causes plasma calcium to be well regulated. Very rapid shape changes of osteoblasts and osteoclasts, in response to hormonal signals, modulate the available bone surfaces so that plasma calcium can increase when more low-affinity bone calcium binding sites are made available and can decrease when more high-affinity binding sites are exposed. The intracellular free calcium concentration of body cells is also regulated, but because cells are bathed by fluids with vastly higher calcium concentration, their major regulatory mechanism is severe entry restriction. All cells have a calcium-sensing receptor that modulates cell function via its response to extracellular calcium. In duodenal cells, the apical calcium entry structure functions as both transporter and a vitamin D–responsive channel. The channel upregulates calcium entry, with intracellular transport mediated by the mobile, vitamin D–dependent buffer, calbindin D9K, which binds and transports more than 90% of the transcellular calcium flux. Fixed intracellular calcium binding sites can, like the body's skeleton, take up and release calcium that has entered the cell, but the principal regulatory tool of the cell is restricted entry.

  14. Multiple Mechanisms Drive Calcium Signal Dynamics around Laser-Induced Epithelial Wounds.

    Science.gov (United States)

    Shannon, Erica K; Stevens, Aaron; Edrington, Westin; Zhao, Yunhua; Jayasinghe, Aroshan K; Page-McCaw, Andrea; Hutson, M Shane

    2017-10-03

    Epithelial wound healing is an evolutionarily conserved process that requires coordination across a field of cells. Studies in many organisms have shown that cytosolic calcium levels rise within a field of cells around the wound and spread to neighboring cells, within seconds of wounding. Although calcium is a known potent second messenger and master regulator of wound-healing programs, it is unknown what initiates the rise of cytosolic calcium across the wound field. Here we use laser ablation, a commonly used technique for the precision removal of cells or subcellular components, as a tool to investigate mechanisms of calcium entry upon wounding. Despite its precise ablation capabilities, we find that this technique damages cells outside the primary wound via a laser-induced cavitation bubble, which forms and collapses within microseconds of ablation. This cavitation bubble damages the plasma membranes of cells it contacts, tens of microns away from the wound, allowing direct calcium entry from extracellular fluid into damaged cells. Approximately 45 s after this rapid influx of calcium, we observe a second influx of calcium that spreads to neighboring cells beyond the footprint of cavitation. The occurrence of this second, delayed calcium expansion event is predicted by wound size, indicating that a separate mechanism of calcium entry exists, corresponding to cell loss at the primary wound. Our research demonstrates that the damage profile of laser ablation is more similar to a crush injury than the precision removal of individual cells. The generation of membrane microtears upon ablation is consistent with studies in the field of optoporation, which investigate ablation-induced cellular permeability. We conclude that multiple types of damage, including microtears and cell loss, result in multiple mechanisms of calcium influx around epithelial wounds. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  15. PESSTO spectroscopic classification of optical transients

    Science.gov (United States)

    Walton, N.; Fraser, M.; Blagorodnova, N.; Taubenberger, S.; Dennefeld, M.; Benetti, S.; Pastorello, A.; Inserra, C.; Smartt, S.; Smith, K.; Young, D.; Sullivan, M.; Valenti, S.; Yaron, O.; Gal-Yam, A.; Knapic, C.; Smareglia, R.; Molinaro, M.; Manulis, I.; Wright, D.; Kotak, R.; Valenti, S.; Burgett, W.; Chambers, K.; Huber, M.; Kudritzki, R. P.; Magnier, E.; Morgan, J.; Stubbs, C.; Sweeney, W.; Tonry, J.; Waters, C.; Draper, P.; Metcalfe, N.; Rest, A.; Baltay, C.; Ellman, N.; Hadjiyska, E.; McKinnon, R.; Rabinowitz, D.; Walker, E. S.; Feindt, U.; Kowalski, M.; Nugent, P.

    2014-03-01

    PESSTO, the Public ESO Spectroscopic Survey for Transient Objects (see Valenti et al., ATel #4037; http://www.pessto.org ), reports the following supernova classifications. Targets were supplied by Pan-STARRS (see Valenti et al., ATel #2668), the La Silla-Quest survey (see Hadjiyska et al., ATel #3812), the Catalina Real-time Transient Survey (http://crts.caltech.edu/), DECam (Forster et al., ATel #5949) and the IAU Transient Objects Confirmation Page list.

  16. Calcium phosphates for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Canillas, M.; Pena, P.; Aza, A.H. de; Rodriguez, M.A.

    2017-07-01

    The history of calcium phosphates in the medicine field starts in 1769 when the first evidence of its existence in the bone tissue is discovered. Since then, the interest for calcium phosphates has increased among the scientific community. Their study has been developed in parallel with new advances in materials sciences, medicine or tissue engineering areas. Bone tissue engineering is the field where calcium phosphates have had a great importance. While the first bioceramics are selected according to bioinert, biocompatibility and mechanical properties with the aim to replace bone tissue damaged, calcium phosphates open the way to the bone tissue regeneration challenge. Nowadays, they are present in the majority of commercial products directed to repair or regenerate damaged bone tissue. Finally, in the last few decades, they have been suggested and studied as drug delivering devices and as vehicles of DNA and RNA for the future generation therapies. (Author)

  17. Polysulfide calcium as multyfunctional product

    Directory of Open Access Journals (Sweden)

    G. Abramova

    2012-12-01

    Full Text Available A modified method of producing of polysulfide calcium, the influence of various factors on the degree of polysulfide of product, as well as possible directions for its use as a multifunctional compound were considered.

  18. [Calcium metabolism after the menopause].

    Science.gov (United States)

    Kanovitch, D; Klotz, H P

    1976-02-16

    The authors recall the antagonism between estradiol and parathormone. Estradiol tends to lower serum calcium and fix calcium in the bones as shown by one of us 25 years ago. The mechanism of this action of estrogen on calcium metabolism has been determined by numerous authors but some points are still not clear, e.g. the interferences between estrogen and calcitonin. Classically, parathormone is known to increase bony reabsorption and raise serum calcium. After the menopause the gradual reduction in estradiol secretion leads to post-menopausal osteoporosis. It is better to administer estrogens prophylactically to women after the menopause provided a cervical smear and mammography have been carried out to eliminate latent carcinoma of the breast or uterine cervix.

  19. Calcium-sensing beyond neurotransmitters

    DEFF Research Database (Denmark)

    Gustavsson, Natalia; Han, Weiping

    2009-01-01

    Neurotransmitters, neuropeptides and hormones are released through the regulated exocytosis of SVs (synaptic vesicles) and LDCVs (large dense-core vesicles), a process that is controlled by calcium. Synaptotagmins are a family of type 1 membrane proteins that share a common domain structure. Most....... Also, we discuss potential roles of synaptotagmins in non-traditional endocrine systems....... synaptotagmins are located in brain and endocrine cells, and some of these synaptotagmins bind to phospholipids and calcium at levels that trigger regulated exocytosis of SVs and LDCVs. This led to the proposed synaptotagmin-calcium-sensor paradigm, that is, members of the synaptotagmin family function...... as calcium sensors for the regulated exocytosis of neurotransmitters, neuropeptides and hormones. Here, we provide an overview of the synaptotagmin family, and review the recent mouse genetic studies aimed at understanding the functions of synaptotagmins in neurotransmission and endocrine-hormone secretion...

  20. Language Delays in Toddlers: Information for Parents

    Science.gov (United States)

    ... Stages Listen Español Text Size Email Print Share Language Delays in Toddlers: Information for Parents Page Content ... situation or repeats scripts from TV Delays in language Delays in language are the most common types ...

  1. Dietary nimodipine delays the onset of methylmercury neurotoxicity in mice.

    Science.gov (United States)

    Bailey, Jordan M; Hutsell, Blake A; Newland, M Christopher

    2013-07-01

    Adult-onset methylmercury (MeHg) exposure is thought to result primarily in sensory and motor deficits but effects on learning are poorly understood. One mechanism by which chronic MeHg may exert its neurotoxicity is via sustained disruption of intracellular calcium homeostasis, with a consequent increase of intracellular Ca(2+) ions in vulnerable neurons. A biochemically heterogeneous group of compounds, calcium channel blockers, have been shown in vitro to attenuate MeHg's toxicity. To evaluate the role of calcium antagonism in MeHg toxicity in vivo, adult BALB/c mice were exposed chronically to 0 or 15 ppm of Hg (as MeHg) via drinking water and to nimodipine, a dihydropryidine, L-type Ca(2+) channel blocker with action in the CNS. Nimodipine was administered orally in diets (0, 20, or 200 ppm, producing approximately 0, 2, or 20 mg/kg/day of nimodipine). An incremental repeated acquisition (IRA) of response chains procedure was used to detect MeHg-induced deficits in learning or motoric function and to evaluate possible neuroprotection by nimodipine. MeHg impaired performance on the IRA task, and this was partially or completely blocked by dietary nimodipine, depending on dose. Measures of learning co-varied with measures of motoric function as indicated by overall response rate. Nimodipine delayed or prevented the behavioral toxicity of MeHg exposure as evidenced by IRA performance; effects on learning seemed secondary to response rate decreases. Copyright © 2013 Elsevier Inc. All rights reserved.

  2. Nuclear reactor transient analysis via a quasi-static kinetics Monte Carlo method

    Energy Technology Data Exchange (ETDEWEB)

    Jo, YuGwon; Cho, Bumhee; Cho, Nam Zin, E-mail: nzcho@kaist.ac.kr [Korea Advanced Institute of Science and Technology 291 Daehak-ro, Yuseong-gu, Daejeon, Korea 305-701 (Korea, Republic of)

    2015-12-31

    The predictor-corrector quasi-static (PCQS) method is applied to the Monte Carlo (MC) calculation for reactor transient analysis. To solve the transient fixed-source problem of the PCQS method, fission source iteration is used and a linear approximation of fission source distributions during a macro-time step is introduced to provide delayed neutron source. The conventional particle-tracking procedure is modified to solve the transient fixed-source problem via MC calculation. The PCQS method with MC calculation is compared with the direct time-dependent method of characteristics (MOC) on a TWIGL two-group problem for verification of the computer code. Then, the results on a continuous-energy problem are presented.

  3. Transient vibration of wind turbine blades

    Science.gov (United States)

    Li, Yuanzhe; Li, Minghai; Jiang, Feng

    2017-09-01

    This article aims to the transient vibration of wind turbine blades. We firstly introduce transient vibration and previous studies in this area. The report then shows the fundamental equations and derivation of Euler Equation. A 3-D beam are created to compare the analytical and numerical result. In addition we operate the existing result and Patran result of a truncation wedge beam, especially the frequencies of free vibration and transient vibration. Transient vibration cannot be vanished but in some case it can be reduced.

  4. 21 CFR 172.330 - Calcium pantothenate, calcium chloride double salt.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium pantothenate, calcium chloride double salt. 172.330 Section 172.330 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN..., calcium chloride double salt. The food additive calcium chloride double salt of calcium pantothenate may...

  5. Filamin and phospholipase C-ε are required for calcium signaling in the Caenorhabditis elegans spermatheca.

    Directory of Open Access Journals (Sweden)

    Ismar Kovacevic

    2013-05-01

    Full Text Available The Caenorhabditis elegans spermatheca is a myoepithelial tube that stores sperm and undergoes cycles of stretching and constriction as oocytes enter, are fertilized, and exit into the uterus. FLN-1/filamin, a stretch-sensitive structural and signaling scaffold, and PLC-1/phospholipase C-ε, an enzyme that generates the second messenger IP3, are required for embryos to exit normally after fertilization. Using GCaMP, a genetically encoded calcium indicator, we show that entry of an oocyte into the spermatheca initiates a distinctive series of IP3-dependent calcium oscillations that propagate across the tissue via gap junctions and lead to constriction of the spermatheca. PLC-1 is required for the calcium release mechanism triggered by oocyte entry, and FLN-1 is required for timely initiation of the calcium oscillations. INX-12, a gap junction subunit, coordinates propagation of the calcium transients across the spermatheca. Gain-of-function mutations in ITR-1/IP3R, an IP3-dependent calcium channel, and loss-of-function mutations in LFE-2, a negative regulator of IP3 signaling, increase calcium release and suppress the exit defect in filamin-deficient animals. We further demonstrate that a regulatory cassette consisting of MEL-11/myosin phosphatase and NMY-1/non-muscle myosin is required for coordinated contraction of the spermatheca. In summary, this study answers long-standing questions concerning calcium signaling dynamics in the C. elegans spermatheca and suggests FLN-1 is needed in response to oocyte entry to trigger calcium release and coordinated contraction of the spermathecal tissue.

  6. Transient global amnesia: current perspectives

    Science.gov (United States)

    Spiegel, David R; Smith, Justin; Wade, Ryan R; Cherukuru, Nithya; Ursani, Aneel; Dobruskina, Yuliya; Crist, Taylor; Busch, Robert F; Dhanani, Rahim M; Dreyer, Nicholas

    2017-01-01

    Transient global amnesia (TGA) is a clinical syndrome characterized by the sudden onset of an extraordinarily large reduction of anterograde and a somewhat milder reduction of retrograde episodic long-term memory. Additionally, executive functions are described as diminished. Although it is suggested that various factors, such as migraine, focal ischemia, venous flow abnormalities, and epileptic phenomena, are involved in the pathophysiology and differential diagnosis of TGA, the factors triggering the emergence of these lesions are still elusive. Recent data suggest that the vulnerability of CA1 neurons to metabolic stress plays a pivotal part in the pathophysiological cascade, leading to an impairment of hippocampal function during TGA. In this review, we discuss clinical aspects, new imaging findings, and recent clinical–epidemiological data with regard to the phenotype, functional anatomy, and putative cellular mechanisms of TGA. PMID:29123402

  7. Transient field generation and measurement

    Science.gov (United States)

    Parkes, D. M.; Smith, P. D.

    The mathematical modeling and numerical computation of the elecromagnetic field radiated by a biconic antenna excited by a transient waveform such as a pulse are outlined. Very good agreement between the model and experiment is achieved for the time history of the radiated pulse. Amplitudes of calculated field strengths are within engineering tolerances. The type of field and its amplitude which result when any variant of biconic antenna is excited by a given input pulse can be predicted, since the time marching method of solving integral equations is shown to be successfully implemented on a computer. Because the system is not limited to single shot events, measurement of induced currents inside target equipments when illuminated by the radiation field is simplified, since sampling technology can be employed. Current waveforms which occur in antennas can also be predicted.

  8. Transient global amnesia: current perspectives.

    Science.gov (United States)

    Spiegel, David R; Smith, Justin; Wade, Ryan R; Cherukuru, Nithya; Ursani, Aneel; Dobruskina, Yuliya; Crist, Taylor; Busch, Robert F; Dhanani, Rahim M; Dreyer, Nicholas

    2017-01-01

    Transient global amnesia (TGA) is a clinical syndrome characterized by the sudden onset of an extraordinarily large reduction of anterograde and a somewhat milder reduction of retrograde episodic long-term memory. Additionally, executive functions are described as diminished. Although it is suggested that various factors, such as migraine, focal ischemia, venous flow abnormalities, and epileptic phenomena, are involved in the pathophysiology and differential diagnosis of TGA, the factors triggering the emergence of these lesions are still elusive. Recent data suggest that the vulnerability of CA1 neurons to metabolic stress plays a pivotal part in the pathophysiological cascade, leading to an impairment of hippocampal function during TGA. In this review, we discuss clinical aspects, new imaging findings, and recent clinical-epidemiological data with regard to the phenotype, functional anatomy, and putative cellular mechanisms of TGA.

  9. Calcium affects on vascular endpoints

    Directory of Open Access Journals (Sweden)

    Patel Vaishali B

    2012-03-01

    Full Text Available Abstract Calcium is one of the most abundant minerals in the body and its metabolism is one of the basic biologic processes in humans. Although historically linked primarily to bone structural development and maintenance, calcium is now recognized as a key component of many physiologic pathways necessary for optimum health including cardiovascular, neurological, endocrine, renal, and gastrointestinal systems. A recent meta-analysis published in August 2011 showed a potential increase in cardiovascular events related to calcium supplementation. The possible mechanism of action of this correlation has not been well elucidated. This topic has generated intense interest due to the widespread use of calcium supplements, particularly among the middle aged and elderly who are at the most risk from cardiac events. Prior studies did not control for potential confounding factors such as the use of statins, aspirin or other medications. These controversial results warrant additional well-designed studies to investigate the relationship between calcium supplementation and cardiovascular outcomes. The purpose of this review is to highlight the current literature in regards to calcium supplementation and cardiovascular health; and to identify areas of future research.

  10. Effect of the RC time on photocurrent transients and determination of charge carrier mobilities

    Science.gov (United States)

    Kniepert, Juliane; Neher, Dieter

    2017-11-01

    We present a closed analytical model to describe time dependent photocurrents upon pulsed illumination in the presence of an external RC circuit. In combination with numerical drift diffusion simulations, it is shown that the RC time has a severe influence on the shape of the transients. In particular, the maximum of the photocurrent is delayed due to a delayed recharging of the electrodes. This delay increases with the increasing RC constant. As a consequence, charge carrier mobilities determined from simple extrapolation of the initial photocurrent decay will be in general too small and feature a false dependence on the electric field. Here, we present a recipe to correct charge carrier mobilities determined from measured photocurrent transients by taking into account the RC time of the experimental set-up. We also demonstrate how the model can be used to more reliably determine the charge carrier mobility from experimental data of a typical polymer/fullerene organic solar cell. It is shown that further aspects like a finite rising time of the pulse generator and the current contribution of the slower charger carriers influence the shape of the transients and may lead to an additional underestimation of the transit time.

  11. Long-Term Blocking of Calcium Channels in mdx Mice Results in Differential Effects on Heart and Skeletal Muscle

    DEFF Research Database (Denmark)

    Jørgensen, Louise Helskov; Blain, Alison; Greally, Elizabeth

    2011-01-01

    calcium ions to enter the cell. The objective of this study was to investigate the effect of chronically blocking calcium channels with the aminoglycoside antibiotic streptomycin from onset of disease in the mdx mouse model of Duchenne muscular dystrophy (DMD). Treatment in utero onwards delayed onset......The disease mechanisms underlying dystrophin-deficient muscular dystrophy are complex, involving not only muscle membrane fragility, but also dysregulated calcium homeostasis. Specifically, it has been proposed that calcium channels directly initiate a cascade of pathological events by allowing...... in older mice. However, streptomycin treatment did not show positive effects in diaphragm or heart muscle, and heart pathology was worsened. Thus, blocking calcium channels even before disease onset does not prevent dystrophy, making this an unlikely treatment for DMD. These findings highlight...

  12. Imaging of Ca2+ transients in cultured neurons by temporal mosaic FLIM (Conference Presentation)

    Science.gov (United States)

    Becker, Wolfgang; Frere, Samuel

    2016-03-01

    We present a technique that records transient changes in the concentration of free calcium in live neurons by TCSPC FLIM. The sample is incubated with a calcium-sensitive dye. To measure the temporal change in the calcium-ion concentration the sample is periodically stimulated by an electrical signal and scanned at high image rate with a high-frequency pulsed laser beam. Single photons of the fluorescence light are detected, and a photon distribution over the coordinates of the scan, the arrival times of the photons after the excitation pulses, and the time after the stimulation pulses is built up. The result can be interpreted as a sequence of FLIM images for different times after the stimulation pulses. The signal-to-noise ratio only depends on the available photon rate and the total acquisition time, not on the speed of the sequence. The maximum resolution at which lifetime changes can be recorded is given by the frame rate of the scanner which is currently 38 ms. Faster changes can be recorded by line scanning. Transient lifetime effects can then be resolved at a resolution of about one millisecond.

  13. Transient receptor potential canonical channel-1 (TRPC1) KO mice that exercise are protected from high-fat diet-induced obesity and type 2 diabetes risk

    Science.gov (United States)

    Objective: Transient receptor potential canonical channel-1 (TRPC1) is a major class of calcium permeable channels found in key metabolic tissues, including the hypothalamus, adipose tissue, and skeletal muscle, making them likely candidates for the regulation of cellular energy metabolism. The exac...

  14. Transition effects on compressible dynamic stall of transiently pitching airfoils

    Science.gov (United States)

    Wilder, M. C.; Chandrasekhara, M. S.; Carr, L. W.

    1993-01-01

    Experimental results and analysis of the effects of boundary layer tripping on dynamic stall of a transiently pitching airfoil are presented. At low Mach numbers, the tripped airfoil exhibits qualitative similarity with the behavior of the untripped airfoil. However, the local supersonic flow at Mach numbers greater than 0.3 is significantly modified by the trip leading to vastly different shock/boundary layer interactions, dynamic stall onset and vortex formation angles. The formation of the laminar separation bubble is found to have a favorable influence in delaying dynamic stall on the untripped airfoil flow. In both Mach number regimes, the tripped flow actually stalls at slightly lower angles of attack. Further experimentation with three trips on an oscillating airfoil showed that the dynamic stall process is very sensitive to the state of the turbulence in the boundary layer. This sensitivity points to a need for finer turbulence modeling techniques for use in dynamic stall computations.

  15. CALCIUM RELEASE FROM INTRACELLULAR STORES IS NECESSARY FOR THE PHOTOPHOBIC RESPONSE IN THE BENTHIC DIATOM NAVICULA PERMINUTA (BACILLARIOPHYCEAE)(1).

    Science.gov (United States)

    McLachlan, Deirdre H; Underwood, Graham J C; Taylor, Alison R; Brownlee, Colin

    2012-06-01

    Complex photoreceptor pathways exist in algae to exploit light as a sensory stimulus. Previous studies have implicated calcium in blue-light signaling in plants and algae. A photophobic response to high-intensity blue light was characterized in the marine benthic diatom Navicula perminuta (Grunow) in van Heurck. Calcium modulators were used to determine the involvement of calcium in the signaling of this response, and the fluorescent calcium indicator Calcium Crimson was used to image changes in intracellular [Ca(2+) ] during a response. A localized, transient elevation of Calcium Crimson fluorescence was seen at the cell tip at the time of cell reversal. Intracellular calcium release inhibitors produced a significant decrease in the population photophobic response. Treatments known to decrease influx of extracellular calcium had no effect on the population photophobic response but did cause a significant decrease in average cell speed. As the increase in intracellular [Ca(2+) ] at the cell tip corresponded to the time of direction change rather than the onset of the light stimulus, it would appear that Ca(2+) constitutes a component of the switching mechanism that leads to reversal of the locomotion machinery. Our current evidence suggests that the source of this Ca(2+) is intracellular. © 2012 Phycological Society of America.

  16. Caffeine-Induced Suppression of GABAergic Inhibition and Calcium-Independent Metaplasticity

    Directory of Open Access Journals (Sweden)

    Masako Isokawa

    2016-01-01

    Full Text Available GABAergic inhibition plays a critical role in the regulation of neuron excitability; thus, it is subject to modulations by many factors. Recent evidence suggests the elevation of intracellular calcium ([Ca2+]i and calcium-dependent signaling molecules underlie the modulations. Caffeine induces a release of calcium from intracellular stores. We tested whether caffeine modulated GABAergic transmission by increasing [Ca2+]i. A brief local puff-application of caffeine to hippocampal CA1 pyramidal cells transiently suppressed GABAergic inhibitory postsynaptic currents (IPSCs by 73.2 ± 6.98%. Time course of suppression and the subsequent recovery of IPSCs resembled DSI (depolarization-induced suppression of inhibition, mediated by endogenous cannabinoids that require a [Ca2+]i rise. However, unlike DSI, caffeine-induced suppression of IPSCs (CSI persisted in the absence of a [Ca2+]i rise. Intracellular applications of BAPTA and ryanodine (which blocks caffeine-induced calcium release from intracellular stores failed to prevent the generation of CSI. Surprisingly, ruthenium red, an inhibitor of multiple calcium permeable/release channels including those of stores, induced metaplasticity by amplifying the magnitude of CSI independently of calcium. This metaplasticity was accompanied with the generation of a large inward current. Although ionic basis of this inward current is undetermined, the present result demonstrates that caffeine has a robust Ca2+-independent inhibitory action on GABAergic inhibition and causes metaplasticity by opening plasma membrane channels.

  17. Regulation of Intestinal Epithelial Calcium Transport Proteins by Stanniocalcin-1 in Caco2 Cells

    Directory of Open Access Journals (Sweden)

    Jinmei Xiang

    2016-07-01

    Full Text Available Stanniocalcin-1 (STC1 is a calcium and phosphate regulatory hormone. However, the exact molecular mechanisms underlying how STC1 affects Ca2+ uptake remain unclear. Here, the expression levels of the calcium transport proteins involved in transcellular transport in Caco2 cells were examined following over-expression or inhibition of STC1. These proteins include the transient receptor potential vanilloid members (TRPV 5 and 6, the plasma membrane calcium ATPase 1b (PMCA1b, the sodium/calcium exchanger (NCX1, and the vitamin D receptor (VDR. Both gene and protein expressions of TRPV5 and TRPV6 were attenuated in response to over-expression of STC1, and the opposite trend was observed in cells treated with siRNASTC1. To further investigate the ability of STC1 to influence TRPV6 expression, cells were treated with 100 ng/mL of recombinant human STC1 (rhSTC1 for 4 h following pre-transfection with siRNASTC1 for 48 h. Intriguingly, the increase in the expression of TRPV6 resulting from siRNASTC1 was reversed by rhSTC1. No significant effect of STC1 on the expression of PMCA1b, NCX1 or VDR was observed in this study. In conclusion, the effect of STC1 on calcium transport in intestinal epithelia is due to, at least in part, its negative regulation of the epithelial channels TRPV5/6 that mediate calcium influx.

  18. Loss of the Inducible Hsp70 Delays the Inflammatory Response to Skeletal Muscle Injury and Severely Impairs Muscle Regeneration

    Science.gov (United States)

    Howard, Travis M.; Ahn, Bumsoo; Ferreira, Leonardo F.

    2013-01-01

    Skeletal muscle regeneration following injury is a highly coordinated process that involves transient muscle inflammation, removal of necrotic cellular debris and subsequent replacement of damaged myofibers through secondary myogenesis. However, the molecular mechanisms which coordinate these events are only beginning to be defined. In the current study we demonstrate that Heat shock protein 70 (Hsp70) is increased following muscle injury, and is necessary for the normal sequence of events following severe injury induced by cardiotoxin, and physiological injury induced by modified muscle use. Indeed, Hsp70 ablated mice showed a significantly delayed inflammatory response to muscle injury induced by cardiotoxin, with nearly undetected levels of both neutrophil and macrophage markers 24 hours post-injury. At later time points, Hsp70 ablated mice showed sustained muscle inflammation and necrosis, calcium deposition and impaired fiber regeneration that persisted several weeks post-injury. Through rescue experiments reintroducing Hsp70 intracellular expression plasmids into muscles of Hsp70 ablated mice either prior to injury or post-injury, we confirm that Hsp70 optimally promotes muscle regeneration when expressed during both the inflammatory phase that predominates in the first four days following severe injury and the regenerative phase that predominates thereafter. Additional rescue experiments reintroducing Hsp70 protein into the extracellular microenvironment of injured muscles at the onset of injury provides further evidence that Hsp70 released from damaged muscle may drive the early inflammatory response to injury. Importantly, following induction of physiological injury through muscle reloading following a period of muscle disuse, reduced inflammation in 3-day reloaded muscles of Hsp70 ablated mice was associated with preservation of myofibers, and increased muscle force production at later time points compared to WT. Collectively our findings indicate that

  19. Calcium: the molecular basis of calcium action in biology and medicine

    National Research Council Canada - National Science Library

    Pochet, Roland; Donato, Rosario

    2000-01-01

    ... of Calcium Calcium Signalling in Excitable Cells Ca2+ Release in Muscle Cells by N. Macrez and J. Mironneau Calcium Signalling in Neurons Exemplified by Rat Sympathetic Ganglion Cells by S.J. M...

  20. Transient receptor potential channels in essential hypertension

    DEFF Research Database (Denmark)

    Liu, Daoyan; Scholze, Alexandra; Zhu, Zhiming

    2006-01-01

    The role of nonselective cation channels of the transient receptor potential channel (TRPC) family in essential hypertension has not yet been investigated.......The role of nonselective cation channels of the transient receptor potential channel (TRPC) family in essential hypertension has not yet been investigated....

  1. simulation of electromagnetic transients in power systems

    African Journals Online (AJOL)

    Dr Obe

    1996-09-01

    Sep 1, 1996 ... Electromagnetic (EM) transients produced by these mathematical models serve as a useful reference in the design of protective devices and fault locators. ... with simulated fault data from electromagnetic. (EM) transients calculation. .... problem in the frequency domain and, finally, taking the inverse Fourier ...

  2. First airborne transient em survey in antarctica

    DEFF Research Database (Denmark)

    Auken, Esben; Mikucki, J. J.; Sørensen, Kurt Ingvard K.I.

    2012-01-01

    A first airborne transient electromagnetic survey was flown in Antarctica in December 2011 with the SkyTEM system. This transient airborne EM system has been optimized in Denmark for almost ten years and was specially designed for ground water mapping. The SkyTEM tool is ideal for mapping...

  3. The LOFAR Transients Key Science Project

    NARCIS (Netherlands)

    Stappers, B.; Fender, R.; Wijers, R.

    2009-01-01

    The Transients Key Science Project (TKP) is one of six Key Science Projects of the next generation radio telescope LOFAR. Its aim is the study of transient and variable low-frequency radio sources with an extremely broad science case ranging from relativistic jet sources to pulsars, exoplanets,

  4. Expression of the high capacity calcium-binding domain of calreticulin increases bioavailable calcium stores in plants

    Science.gov (United States)

    Wyatt, Sarah E.; Tsou, Pei-Lan; Robertson, Dominique; Brown, C. S. (Principal Investigator)

    2002-01-01

    Modulation of cytosolic calcium levels in both plants and animals is achieved by a system of Ca2+-transport and storage pathways that include Ca2+ buffering proteins in the lumen of intracellular compartments. To date, most research has focused on the role of transporters in regulating cytosolic calcium. We used a reverse genetics approach to modulate calcium stores in the lumen of the endoplasmic reticulum. Our goals were two-fold: to use the low affinity, high capacity Ca2+ binding characteristics of the C-domain of calreticulin to selectively increase Ca2+ storage in the endoplasmic reticulum, and to determine if those alterations affected plant physiological responses to stress. The C-domain of calreticulin is a highly acidic region that binds 20-50 moles of Ca2+ per mole of protein and has been shown to be the major site of Ca2+ storage within the endoplasmic reticulum of plant cells. A 377-bp fragment encoding the C-domain and ER retention signal from the maize calreticulin gene was fused to a gene for the green fluorescent protein and expressed in Arabidopsis under the control of a heat shock promoter. Following induction on normal medium, the C-domain transformants showed delayed loss of chlorophyll after transfer to calcium depleted medium when compared to seedlings transformed with green fluorescent protein alone. Total calcium measurements showed a 9-35% increase for induced C-domain transformants compared to controls. The data suggest that ectopic expression of the calreticulin C-domain increases Ca2+ stores, and that this Ca2+ reserve can be used by the plant in times of stress.

  5. Rapid measurement of transient velocity evolution using GERVAIS.

    Science.gov (United States)

    Davies, Colin J; Sederman, Andrew J; Pipe, Chris J; McKinley, Gareth H; Gladden, Lynn F; Johns, Mike L

    2010-01-01

    Rapid velocity measurements using GERVAIS (Gradient Echo Rapid Velocity and Acceleration Imaging Sequence), an EPI (Echo Planar Imaging) based technique capable of measuring velocity over an observation time of several milliseconds, are performed on a wide-gap Couette Rheo-NMR cell for the first time. A variable delay time between a control signal to initiate a transition in flow and the start of the measurement sequence is incorporated to allow investigation of the transient evolution of the velocity field following a step change in rotation rate. Both the commencement and the cessation of imposed shear stress are investigated for (i) a shear banding micellar solution of CPyCl (cetylpyridiniumchloride)/NaSal (sodium salicylate) in brine and (ii) a low molecular weight PDMS (polydimethylsiloxane) oil. With respect to the micellar solution, an elastic shear wave is seen to propagate across the cell following the commencement of shear stress whilst an oscillatory 'recoil' is observed following the cessation of shear stress; neither of these phenomena were observed for the PDMS oil which exhibited a purely viscous response as expected for an incompressible Newtonian fluid. This technique has potential applications across a wide range of transient rheological investigations, particularly with respect to optically opaque materials. Copyright 2009 Elsevier Inc. All rights reserved.

  6. Multibeam Gpu Transient Pipeline for the Medicina BEST-2 Array

    Science.gov (United States)

    Magro, A.; Hickish, J.; Adami, K. Z.

    2013-09-01

    Radio transient discovery using next generation radio telescopes will pose several digital signal processing and data transfer challenges, requiring specialized high-performance backends. Several accelerator technologies are being considered as prototyping platforms, including Graphics Processing Units (GPUs). In this paper we present a real-time pipeline prototype capable of processing multiple beams concurrently, performing Radio Frequency Interference (RFI) rejection through thresholding, correcting for the delay in signal arrival times across the frequency band using brute-force dedispersion, event detection and clustering, and finally candidate filtering, with the capability of persisting data buffers containing interesting signals to disk. This setup was deployed at the BEST-2 SKA pathfinder in Medicina, Italy, where several benchmarks and test observations of astrophysical transients were conducted. These tests show that on the deployed hardware eight 20 MHz beams can be processed simultaneously for 640 Dispersion Measure (DM) values. Furthermore, the clustering and candidate filtering algorithms employed prove to be good candidates for online event detection techniques. The number of beams which can be processed increases proportionally to the number of servers deployed and number of GPUs, making it a viable architecture for current and future radio telescopes.

  7. A Single Nucleotide Polymorphism (rs4236480 in TRPV5 Calcium Channel Gene Is Associated with Stone Multiplicity in Calcium Nephrolithiasis Patients

    Directory of Open Access Journals (Sweden)

    Anas Khaleel

    2015-01-01

    Full Text Available Nephrolithiasis is characterized by calcification of stones in the kidneys from an unknown cause. Animal models demonstrated the functional roles of the transient receptor potential vanilloid member 5 (TRPV5 gene in calcium renal reabsorption and hypercalciuria. Therefore, TRPV5 was suggested to be involved in calcium homeostasis. However, whether genetic polymorphisms of TRPV5 are associated with kidney stone multiplicity or recurrence is unclear. In this study, 365 Taiwanese kidney-stone patients were recruited. Both biochemical data and DNA samples were collected. Genotyping was performed by a TaqMan allelic discrimination assay. We found that a TRPV5 polymorphism (rs4236480 was observed to be associated with stone multiplicity of calcium nephrolithiasis, as the risk of stone multiplicity was higher in patients with the TT+CT genotype than in patients with the CC genotype (p=0.0271. In summary, despite the complexity of nephrolithiasis and the potential association of numerous calcium homeostatic absorption/reabsorption factors, TRPV5 plays an important role in the pathogenesis of calcium nephrolithiasis.

  8. Transient Neurological Symptoms after Spinal Anesthesia

    Directory of Open Access Journals (Sweden)

    Zehra Hatipoglu

    2013-02-01

    Full Text Available Lidocaine has been used for more than 50 years for spinal anesthesia and has a remarkable safety record. In 1993, a new adverse effect, transient neurologic toxicity was described in patients recovering from spinal anesthesia with lidocaine. Transient neurological symptoms have been defined as pain in the lower extremities (buttocks, thighs and legs after an uncomplicated spinal anesthesia and after an initial full recovery during the immediate postoperative period (less than 24 h. The incidence of transient neurological symptoms reported in prospective, randomized trials varies from 4% to 37%. The etiology of transient neurological symptoms remains unkonwn. Despite the transient nature of this syndrome, it has proven to be difficult to treat effectively. Drug or some interventional therapy may be necessary. [Archives Medical Review Journal 2013; 22(1.000: 33-44

  9. Machine Learning for Zwicky Transient Facility

    Science.gov (United States)

    Mahabal, Ashish; Zwicky Transient Facility, Catalina Real-Time Transient Survey

    2018-01-01

    The Zwicky Transient Facility (ZTF) will operate from 2018 to 2020 covering the accessible sky with its large 47 square degree camera. The transient detection rate is expected to be about a million per night. ZTF is thus a perfect LSST prototype. The big difference is that all of the ZTF transients can be followed up by 4- to 8-m class telescopes. Given the large numbers, using human scanners for separating the genuine transients from artifacts is out of question. For that first step as well as for classifying the transients with minimal follow-up requires machine learning. We describe the tools and plans to take on this task using follow-up facilities, and knowledge gained from archival datasets.

  10. Presynaptic calcium signalling in cerebellar mossy fibres

    DEFF Research Database (Denmark)

    Thomsen, Louiza Bohn; Jörntell, Henrik; Midtgaard, Jens

    2010-01-01

    Whole-cell recordings were obtained from mossy fibre terminals in adult turtles in order to characterize the basic membrane properties. Calcium imaging of presynaptic calcium signals was carried out in order to analyse calcium dynamics and presynaptic GABA B inhibition. A tetrodotoxin (TTX....... Calcium imaging using Calcium-Green dextran revealed a stimulus-evoked all-or-none TTX-sensitive calcium signal in simple and complex rosettes. All compartments of a complex rosette were activated during electrical activation of the mossy fibre, while individual simple and complex rosettes along an axon...... appeared to be isolated from one another in terms of calcium signalling. CGP55845 application showed that GABA B receptors mediated presynaptic inhibition of the calcium signal over the entire firing frequency range of mossy fibres. A paired-pulse depression of the calcium signal lasting more than 1 s...

  11. Energetic ion leakage from foreshock transient cores

    Science.gov (United States)

    Liu, Terry Z.; Angelopoulos, Vassilis; Hietala, Heli

    2017-07-01

    Earth's foreshock is filled with backstreaming particles that can interact with the ambient solar wind and its discontinuities to form foreshock transients. Many foreshock transients have a core with low dynamic pressure that can significantly perturb the bow shock and the magnetosphere-ionosphere system. Foreshock transients have also been recently recognized as sites of particle acceleration, which may be important for seeding the parent shock with energetic particles. A relevant step of this seeding would be energetic ion leakage into the surrounding foreshock environment. On the other hand, such leakage would also suppress the energetic particle flux contrast across foreshock transients' boundaries masking their perceived contribution to ion energization. To further examine this hypothesis of ion leakage, we report on multipoint case studies of three foreshock transient events selected from a large database. The cases were selected to exemplify, in increasing complexity, the nature and consequences of energetic ion leakage. Ion energy dispersion, observed upstream and/or downstream of the foreshock transients, is explained with a simple, ballistic model of ions leaking from the foreshock transients. Larger energies are required for leaked ions to reach the spacecraft as the distance between the transient and spacecraft increases. Our model, which explains well the observed ion energy dispersion and velocity distributions, can also be used to reveal the shape of the foreshock transients in three dimensions. Our results suggest that ion leakage from foreshock transient cores needs to be accounted for both in statistical studies and in global models of ion acceleration under quasi-parallel foreshock conditions.

  12. Stochastic modelling of train delays and delay propagation in stations

    NARCIS (Netherlands)

    Yuan, J.

    2006-01-01

    A trade-off exists between efficiently utilizing the capacity of railway networks and improving the reliability and punctuality of train operations. This dissertation presents a new analytical probability model based on blocking time theory which estimates the knock-on delays of trains caused by

  13. Justice Delayed is Justice Denied

    Directory of Open Access Journals (Sweden)

    Naomi Burstyner

    2014-10-01

    Full Text Available This paper explores issues in the justice system that are related to timeliness and its interconnectedness to the definition of delay, whilst considering the impact of delay on the experience of the justice system user.Historical acknowledgements recognise the perspective of the accused or the disputant, and suggest that for a person seeking justice, the time taken for resolution of their issue is critical to the justice experience of this person and can render their treatment wholly ‘unjust’ in circumstances where closure takes ‘too long’.

  14. 49 CFR 236.563 - Delay time.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Delay time. 236.563 Section 236.563 Transportation... Cab Signal Systems Rules and Instructions; Locomotives § 236.563 Delay time. Delay time of automatic... requirements of § 236.24 shall take into consideration the delay time. ...

  15. Transient thermohydraulic heat pipe modeling

    Science.gov (United States)

    Hall, Michael L.; Doster, Joseph M.

    Many space based reactor designs employ heat pipes as a means of conveying heat. In these designs, thermal radiation is the principle means for rejecting waste heat from the reactor system, making it desirable to operate at high temperatures. Lithium is generally the working fluid of choice as it undergoes a liquid-vapor transformation at the preferred operating temperature. The nature of remote startup, restart, and reaction to threats necessitates an accurate, detailed transient model of the heat pipe operation. A model is outlined of the vapor core region of the heat pipe which is part of a large model of the entire heat pipe thermal response. The vapor core is modeled using the area averaged Navier-Stokes equations in one dimension, which take into account the effects of mass, energy and momentum transfer. The core model is single phase (gaseous), but contains two components: lithium gas and a noncondensible vapor. The vapor core model consists of the continuity equations for the mixture and noncondensible, as well as mixture equations for internal energy and momentum.

  16. Clinical applications of transient elastography

    Directory of Open Access Journals (Sweden)

    Kyu Sik Jung

    2012-06-01

    Full Text Available Chronic liver disease represents a major public health problem, accounting for significant morbidity and mortality worldwide. As prognosis and management depend mainly on the amount and progression of liver fibrosis, accurate quantification of liver fibrosis is essential for therapeutic decision-making and follow-up of chronic liver diseases. Even though liver biopsy is the gold standard for evaluation of liver fibrosis, non-invasive methods that could substitute for invasive procedures have been investigated during past decades. Transient elastography (TE, FibroScan® is a novel non-invasive method for assessment of liver fibrosis with chronic liver disease. TE can be performed in the outpatient clinic with immediate results and excellent reproducibility. Its diagnostic accuracy for assessment of liver fibrosis has been demonstrated in patients with chronic viral hepatitis; as a result, unnecessary liver biopsy could be avoided in some patients. Moreover, due to its excellent patient acceptance, TE could be used for monitoring disease progression or predicting development of liver-related complications. This review aims at discussing the usefulness of TE in clinical practice.

  17. Calcium metabolism and cardiovascular function after spaceflight

    Science.gov (United States)

    Hatton, Daniel C.; Yue, Qi; Dierickx, Jacqueline; Roullet, Chantal; Otsuka, Keiichi; Watanabe, Mitsuaki; Coste, Sarah; Roullet, Jean Baptiste; Phanouvang, Thongchan; Orwoll, Eric; hide

    2002-01-01

    To determine the influence of dietary calcium on spaceflight-induced alterations in calcium metabolism and blood pressure (BP), 9-wk-old spontaneously hypertensive rats, fed either high- (2%) or low-calcium (0.02%) diets, were flown on an 18-day shuttle flight. On landing, flight animals had increased ionized calcium (P parathyroid hormone levels (P animals (P = 0.057). However, mean arterial pressure was elevated (P animals fed low- compared with high-calcium diets (P parathyroid hormone was paradoxically increased in the high-calcium-fed flight animals after landing.

  18. A genetic algorithm based remaining lifetime prediction for a VLIW processor employing path delay and IDDX testing

    NARCIS (Netherlands)

    Kerkhoff, Hans G.; Zhao, Yong

    2016-01-01

    In this paper, critical path-delay time, and quiescent and transient power-supply current testing have been applied to a 90nm VLIW processor, to predict the remaining lifetime of this processor. The test environment for validation, via implementing an accelerated test has been realized. The

  19. Effects of caffeine on calcium release from the sarcoplasmic reticulum in frog skeletal muscle fibres.

    Science.gov (United States)

    Klein, M G; Simon, B J; Schneider, M F

    1990-06-01

    1. Resting myoplasmic [Ca2+] and [Ca2+] transients (delta [Ca2+]) were monitored using Fura-2 fluorescence and Antipyrylazo III absorbance signals from voltage-clamped segments of cut frog skeletal muscle fibres in the presence and absence of 0.5 mM-caffeine. The rate of release (Rrel) of calcium from the sarcoplasmic reticulum was calculated from delta [Ca2+]. 2. delta [Ca2+] and Rrel were increased in caffeine for all pulses. The decline of delta [Ca2+] was slower after a given pulse in caffeine than without caffeine. Resting [Ca2+] was slightly elevated in caffeine. 3. The voltage dependence of the peak value of Rrel and of the steady level of Rrel at the end of a 60-120 ms pulse were both shifted towards more negative voltages in caffeine. For relatively small pulses the voltage at which a given release waveform was observed was also shifted to more negative voltages. 4. Intramembrane charge movements measured in the same fibres in which the above changes in Rrel were observed showed no significant changes in caffeine. 5. In caffeine calcium release continued for many milliseconds after the end of a short (10 ms) pulse. Continued release after a pulse was not observed without caffeine and was probably due to positive feedback of elevated [Ca2+] on calcium release resulting from calcium-induced calcium release in caffeine. 6. Intramembrane charge movements after short pulses showed no change in caffeine that could account for the continued calcium release after the pulse. 7. Continued release after short pulses in caffeine decreased as the pulse duration was increased and was absent for pulses of 60 ms or longer. Rrel also inactivated during such pulses. 8. Relatively large and long conditioning pulses in caffeine suppressed both the peak Rrel and the continued release after short pulses. Peak release and continued release after short pulses recovered in parallel with increasing recovery time following suppression by a conditioning pulse in caffeine. 9. These

  20. [Regulatory mechanism of calcium metabolism.

    Science.gov (United States)

    Ozono, Keiichi

    It is often difficult for terrestrial animals to take enough calcium. To maintain serum or extracellular calcium levels is very important for muscle and nerve function. Two major regulators to increase the serum calcium levels are parathyroid hormone(PTH)and vitamin D. PTH binds to the G protein coupling receptor, PTH1R, and increases intracellular cAMP levels. Impirement in the PTH signalling causes many diseases such as pseudohypoparathyroidism and acrodysostosis with hormone resistance. Vitamin D is activated to 1,25-dihydroxyvitamin D[1,25(OH)2D]by two steps of hydroxylation which occurs in the Liver and Kidney. Then, 1,25(OH)2D binds to vitamin D receptor(VDR), which works as a ligand-dependent transcription factor. Hypocalcemia and hypercalcemia are caused by various disorders including abnormal regulation of PTH and vitamin D production and their signal transduction.

  1. Calcium signaling and cell proliferation.

    Science.gov (United States)

    Pinto, Mauro Cunha Xavier; Kihara, Alexandre Hiroaki; Goulart, Vânia A M; Tonelli, Fernanda M P; Gomes, Katia N; Ulrich, Henning; Resende, Rodrigo R

    2015-11-01

    Cell proliferation is orchestrated through diverse proteins related to calcium (Ca(2+)) signaling inside the cell. Cellular Ca(2+) influx that occurs first by various mechanisms at the plasma membrane, is then followed by absorption of Ca(2+) ions by mitochondria and endoplasmic reticulum, and, finally, there is a connection of calcium stores to the nucleus. Experimental evidence indicates that the fluctuation of Ca(2+) from the endoplasmic reticulum provides a pivotal and physiological role for cell proliferation. Ca(2+) depletion in the endoplasmatic reticulum triggers Ca(2+) influx across the plasma membrane in an phenomenon called store-operated calcium entries (SOCEs). SOCE is activated through a complex interplay between a Ca(2+) sensor, denominated STIM, localized in the endoplasmic reticulum and a Ca(2+) channel at the cell membrane, denominated Orai. The interplay between STIM and Orai proteins with cell membrane receptors and their role in cell proliferation is discussed in this review. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. Multimodal pore formation in calcium phosphate cements.

    Science.gov (United States)

    Lodoso-Torrecilla, Irene; van Gestel, Nicole A P; Diaz-Gomez, Luis; Grosfeld, Eline-Claire; Laperre, Kjell; Wolke, Joop G C; Smith, Brandon T; Arts, Jacobus J; Mikos, Antonios G; Jansen, John A; Hofmann, Sandra; van den Beucken, Jeroen J J P

    2017-09-23

    Calcium phosphate cements (CPCs) are commonly used as bone substitute materials. However, their slow degradation rate and lack of macroporosity hinders new bone formation. Poly(dl-lactic-co-glycolic acid) (PLGA) incorporation is of great interest as, upon degradation, produces acidic by-products that enhance CPC degradation. Yet, new bone formation is delayed until PLGA degradation occurs a few weeks after implantation. Therefore, the aim of this study was to accelerate the early stage pore formation within CPCs in vitro. With that purpose, we incorporated the water-soluble porogen sucrose at different weight percentages (10 or 20 wt %) to CPC and CPC/PLGA composites. The results revealed that incorporation of sucrose porogens increased mass loss within the first week of in vitro degradation in groups containing sucrose compared to control groups. After week 1, a further mass loss was observed related to PLGA and CPC degradation. Macroporosity analysis confirmed that macroporosity formation is influenced by the dissolution of sucrose at an early stage and by the degradation of PLGA and CPC at a later stage. We concluded that the combination of sucrose and PLGA porogens in CPC is a promising approach to promote early stage bone tissue ingrowth and complete replacement of CPC through multimodal pore formation. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2017. © 2017 Wiley Periodicals, Inc.

  3. Predictive active disturbance rejection control for processes with time delay.

    Science.gov (United States)

    Zheng, Qinling; Gao, Zhiqiang

    2014-07-01

    Active disturbance rejection control (ADRC) has been shown to be an effective tool in dealing with real world problems of dynamic uncertainties, disturbances, nonlinearities, etc. This paper addresses its existing limitations with plants that have a large transport delay. In particular, to overcome the delay, the extended state observer (ESO) in ADRC is modified to form a predictive ADRC, leading to significant improvements in the transient response and stability characteristics, as shown in extensive simulation studies and hardware-in-the-loop tests, as well as in the frequency response analysis. In this research, it is assumed that the amount of delay is approximately known, as is the approximated model of the plant. Even with such uncharacteristic assumptions for ADRC, the proposed method still exhibits significant improvements in both performance and robustness over the existing methods such as the dead-time compensator based on disturbance observer and the Filtered Smith Predictor, in the context of some well-known problems of chemical reactor and boiler control problems. © 2013 Published by ISA on behalf of ISA.

  4. Calcium regulation of muscle contraction.

    Science.gov (United States)

    Szent-Györgyi, A G

    1975-07-01

    Calcium triggers contraction by reaction with regulatory proteins that in the absence of calcium prevent interaction of actin and myosin. Two different regulatory systems are found in different muscles. In actin-linked regulation troponin and tropomyosin regulate actin by blocking sites on actin required for complex formation with myosin; in myosin-linked regulation sites on myosin are blocked in the absence of calcium. The major features of actin control are as follows: there is a requirement for tropomyosin and for a troponin complex having three different subunits with different functions; the actin displays a cooperative behavior; and a movement of tropomyosin occurs controlled by the calcium binding on troponin. Myosin regulation is controlled by a regulatory subunit that can be dissociated in scallop myosin reversibly by removing divalent cations with EDTA. Myosin control can function with pure actin in the absence of tropomyosin. Calcium binding and regulation of molluscan myosins depend on the presence of regulatory light chains. It is proposed that the light chains function by sterically blocking myosin sites in the absence of calcium, and that the "off" state of myosin requires cooperation between the two myosin heads. Both myosin control and actin control are widely distributed in different organisms. Many invertebrates have muscles with both types of regulation. Actin control is absent in the muscles of molluscs and in several minor phyla that lack troponin. Myosin control is not found in striated vertebrate muscles and in the fast muscles of crustacean decapods, although regulatory light chains are present. While in vivo myosin control may not be excluded from vertebrate striated muscles, myosin control may be absent as a result of mutations of the myosin heavy chain.

  5. Livermore blasted for project delay

    CERN Multimedia

    1999-01-01

    In a 12 page report issued last week, a review committee set up by the University of California has concluded that mismanagement and poor planning are to blame for significant cost overruns and delays in the construction of NIF, the worlds largest laser (1 page).

  6. EAMJ Delayed April 10.indd

    African Journals Online (AJOL)

    2010-04-04

    Apr 4, 2010 ... Patient delay accounts for a large proportion of those who present with late stage disease especially ... Data collection: All patients diagnosed with breast cancer who certified the inclusion criteria were ..... Ingram, D.M., Huang, H.Y., Catchpole, B.N. and. Roberts, A. Do big breasts disadvantage women with.

  7. Diagnostic Delay in Rheumatoid Arthritis

    DEFF Research Database (Denmark)

    Mølbaek, Karen; Hørslev-Petersen, Kim; Primdahl, Jette

    2016-01-01

    BACKGROUND: To prevent joint damage among patients with rheumatoid arthritis (RA), there is a need to minimize delays from the onset of symptoms until the initiation of appropriate therapy. The present study explored the factors that have an impact on the time it takes for Danish patients with RA...

  8. Design flaw could delay collider

    CERN Multimedia

    Cho, Adrian

    2007-01-01

    "A magnet for the Large Hadron Collider (LHC) failed during a key test at the European particle physics laboratory CERN last week. Physicists and engineers will have to repair the damaged magnet and retrofit others to correct the underlynig design flaw, which could delay the start-up of the mammouth subterranean machine." (1,5 page)

  9. Delayed logistic population models revisited

    OpenAIRE

    Liz, Eduardo

    2014-01-01

    We discuss the global dynamics of some logistic models governed by delay-differential equations. We focus on models of exploited populations, and study the changes in the dynamics as the harvesting effort is increased. We get new results and highlight the link among different logistic equations usually employed in population models.

  10. Providing delay guarantees in Bluetooth

    NARCIS (Netherlands)

    Ait Yaiz, R.; Heijenk, Geert; Titsworth, F.

    2003-01-01

    Bluetooth polling, also referred to as Bluetooth MAC scheduling or intra-piconet scheduling, is the mechanism that schedules the traffic between the participants in a Bluetooth network. Hence, this mechanism is highly determining with respect to the delay packets experience in a Bluetooth network.

  11. Tooth formation - delayed or absent

    Science.gov (United States)

    ... tooth formation; Teeth - delayed or absent formation Images Tooth anatomy Development of baby teeth Development of permanent teeth References ... MO: Elsevier Mosby; 2016:chap 19. Tinanoff N. Development and developmental anomalies of the teeth. In: Kliegman RM, ... NIH MedlinePlus Magazine Read more ...

  12. Early-delayed radiation rhombencephalopathy

    Energy Technology Data Exchange (ETDEWEB)

    Nightingale, S.; Dawes, P.J.D.K.; Cartlidge, N.E.F. (Royal Victoria Infirmary, Newcastle upon Tyne (UK); Newcastle upon Tyne Univ. (UK). Newcastle General Hospital)

    1982-03-01

    A 37-year-old woman developed an early-delayed rhombencephalopathy 7 weeks after completing a course of radiotherapy to a glomus jugulare tumour. The clinical features, comprising nystagmus, skew strabismus, unilateral facial weakness, dysarthria and ataxia, are compared with four previously reported patients with this syndrome.

  13. Deconstructing delayed posttraumatic stress disorder

    NARCIS (Netherlands)

    Smid, G

    2011-01-01

    According to the Diagnostic and Statistical Manual of Mental Disorders, delayed posttraumatic stress disorder (PTSD) must be diagnosed in individuals fulfilling criteria for PTSD if the onset of symptoms is at least six months after the trauma. The purpose of this thesis was to establish the

  14. Graviditetsudløst transient osteoporose som årsag til hoftesmerter post partum

    DEFF Research Database (Denmark)

    Svensson, Annemarie Lyng; Jensen, Jens-Erik Beck; Morsel-Carlsen, Lone

    2014-01-01

    Transient osteoporosis of the hip (TOH) affects pregnant women in the third trimester of pregnancy. Magnetic resonance imaging plays an important role in the diagnosis and shows a pattern of bone marrow oedema. We report a case of TOH post-partum with involvement of both hips in a 34-year-old woman....... She was known with undifferentiated spondyloartritis since 2004, which posed a diagnostic challenge. The reported patient was treated conservatively avoiding lactation, weight bearing activities, increased intake of calcium and vitamin D and recovered without further medical treatment....

  15. Despite differences in cytosolic calcium regulation, lidocaine toxicity is similar in adult and neonatal rat dorsal root ganglia in vitro.

    Science.gov (United States)

    Doan, Lisa V; Eydlin, Olga; Piskoun, Boris; Kline, Richard P; Recio-Pinto, Esperanza; Rosenberg, Andrew D; Blanck, Thomas J J; Xu, Fang

    2014-01-01

    Neuraxial local anesthetics may have neurological complications thought to be due to neurotoxicity. A primary site of action of local anesthetics is the dorsal root ganglia (DRG) neuron. Physiologic differences have been noted between young and adult DRG neurons; hence, the authors examined whether there were any differences in lidocaine-induced changes in calcium and lidocaine toxicity in neonatal and adult rat DRG neurons. DRG neurons were cultured from postnatal day 7 (P7) and adult rats. Lidocaine-induced changes in cytosolic calcium were examined with the calcium indicator Fluo-4. Cells were incubated with varying concentrations of lidocaine and examined for viability using calcein AM and ethidium homodimer-1 staining. Live imaging of caspase-3/7 activation was performed after incubation with lidocaine. The mean KCl-induced calcium transient was greater in P7 neurons (P lidocaine significantly inhibited KCl-induced calcium responses in both ages (P lidocaine, KCl-induced calcium transients in both ages became more homogeneous but remained different between the groups. Interestingly, cell viability was decreased by lidocaine in a dose-dependent manner similarly in both ages. Lidocaine treatment also activated caspase-3/7 in a dose- and time-dependent manner similarly in both ages. Despite physiological differences in P7 and adult DRG neurons, lidocaine cytotoxicity is similar in P7 and adult DRG neurons in vitro. Differences in lidocaine- and KCl-evoked calcium responses suggest the similarity in lidocaine cytotoxicity involves other actions in addition to lidocaine-evoked effects on cytosolic calcium responses.

  16. Despite Differences in Cytosolic Calcium Regulation, Lidocaine Toxicity Is Similar in Adult and Neonatal Rat Dorsal Root Ganglia in Vitro

    Science.gov (United States)

    Doan, Lisa V.; Eydlin, Olga; Piskoun, Boris; Kline, Richard P; Recio-Pinto, Esperanza; Rosenberg, Andrew D; Blanck, Thomas JJ; Xu, Fang

    2013-01-01

    Background Neuraxial local anesthetics may have neurological complications thought to be due to neurotoxicity. A primary site of action for local anesthetics is the dorsal root ganglia (DRG) neuron. Physiologic differences have been noted between young and adult DRG neurons; hence, we examined whether there were differences in lidocaine-induced changes in calcium and lidocaine toxicity in neonatal and adult rat DRG neurons. Methods DRG neurons were cultured from postnatal day 7 (P7) and adult rats. Lidocaine-induced changes in cytosolic calcium were examined with the calcium indicator Fluo-4. Cells were incubated with varying concentrations of lidocaine and examined for viability using calcein AM and ethidium homodimer-1 staining. Live imaging of caspase-3/7 activation was performed after incubation with lidocaine. Results The mean KCl-induced calcium transient was greater in P7 neurons (p lidocaine significantly inhibited KCl-induced calcium responses in both ages (p lidocaine, KCl-induced calcium transients in both ages became more homogeneous but remained different between the groups. Interestingly cell viability was decreased by lidocaine in a dose-dependent manner similarly in both ages. Lidocaine treatment also activated caspase-3/7 in a dose- and time-dependent manner similarly in both ages. Conclusions Despite physiological differences in P7 and adult DRG neurons, lidocaine cytotoxicity is similar in P7 and adult DRG neurons in vitro. Differences in lidocaine- and KCl-evoked calcium responses suggest the similarity in lidocaine cytotoxicity involves other actions in addition to lidocaine-evoked effects on cytosolic calcium responses. PMID:23851347

  17. Can total cardiac calcium predict the coronary calcium score?

    Science.gov (United States)

    Pressman, Gregg S; Crudu, Vitalie; Parameswaran-Chandrika, Anoop; Romero-Corral, Abel; Purushottam, Bhaskar; Figueredo, Vincent M

    2011-01-21

    Mitral annular calcification (MAC) shares the same risk factors as atherosclerosis and is associated with coronary artery disease as well as cardiovascular events. However, sensitivity and positive predictive value are low. We hypothesized that a global echocardiographic calcium score would better predict coronary atherosclerotic burden, as assessed by coronary artery calcium score (CAC), than MAC alone. An echocardiographic score was devised to measure global cardiac calcification in a semi-quantitative manner; this included calcification in the aortic valve and root, the mitral valve and annulus, and the sub-mitral apparatus. This score, and a simplified version, were compared with a similar calcification score by CT scan, as well as the CAC. There was a good correlation between the two global calcification scores; the echocardiographic score also correlated with CAC. Using CAC >400 as a measure of severe coronary atherosclerosis, an echocardiographic score ≥5 had a positive predictive value of 60%. Importantly, the simplified score performed equally well (≥3 had a positive predictive value of 62%). Global cardiac calcification, assessed by CT scan or echocardiography, correlates with the extent of coronary calcium. A semi-quantitative calcium score can be easily applied during routine echocardiographic interpretation and can alert the reader to the possibility of severe coronary atherosclerosis. Copyright © 2009 Elsevier Ireland Ltd. All rights reserved.

  18. Calcium ferrite formation from the thermolysis of calcium tris (maleato)

    Indian Academy of Sciences (India)

    stoichiometric quantities of aqueous solutions of calcium maleate, iron(III) maleate and maleic acid. The reaction mixture was concentrated on a water bath until a brown coloured product formed after the addition of excess of acetone. The complex was vacuum dried and its identity was established by chemical analysis.

  19. Calcium ferrite formation from the thermolysis of calcium tris ...

    Indian Academy of Sciences (India)

    Various physico-chemical techniques i.e. TG, DTG, DTA, Mössbauer, XRD, IR etc have been used to study the decomposition behaviour from ambient to 900°C and ferrite formation. Three consecutive decomposition steps leading to the formation of -Fe2O3 and calcium carbonate have been observed at various stages of ...

  20. Calcium Carbonate versus Sevelamer Hydrochloride as Phosphate Binders after Long-Term Disease Progression in 5/6 Nephrectomized Rats

    Directory of Open Access Journals (Sweden)

    Suvi Törmänen

    2014-01-01

    Full Text Available Our aim was to compare the effects of calcium carbonate and sevelamer-HCl treatments on calcium-phosphate metabolism and renal function in 5/6 nephrectomized (NX rats so that long-term disease progression preceded the treatment. After 15-week progression, calcium carbonate (3.0%, sevelamer-HCl (3.0%, or control diets (0.3% calcium were given for 9 weeks. Subtotal nephrectomy reduced creatinine clearance (−40%, plasma calcidiol (−25%, and calcitriol (−70% and increased phosphate (+37%, parathyroid hormone (PTH (11-fold, and fibroblast growth factor-23 (FGF-23 (4-fold. In NX rats, calcium carbonate diet increased plasma (+20% and urinary calcium (6-fold, reduced plasma phosphate (−50% and calcidiol (−30%, decreased creatinine clearance (−35% and FGF 23 (−85%, and suppressed PTH without influencing blood pH. In NX rats, sevelamer-HCl increased urinary calcium (4-fold and decreased creatinine clearance (−45%, PTH (−75%, blood pH (by 0.20 units, plasma calcidiol (−40%, and calcitriol (−65%. Plasma phosphate and FGF-23 were unchanged. In conclusion, when initiated after long-term progression of experimental renal insufficiency, calcium carbonate diet reduced plasma phosphate and FGF-23 while sevelamer-HCl did not. The former induced hypercalcemia, the latter induced acidosis, while both treatments reduced vitamin D metabolites and deteriorated renal function. Thus, delayed initiation influences the effects of these phosphate binders in remnant kidney rats.

  1. Transient epileptic amnesia: a concise review.

    Science.gov (United States)

    Asadi-Pooya, Ali A

    2014-02-01

    Transient epileptic amnesia (TEA) is a distinctive syndrome and comprises episodic transient amnesia with an epileptic basis, without impairment of other aspects of cognitive function. Additional interictal memory deficits are common in TEA. An epileptic origin, after other etiologies have been excluded, should be considered and carefully investigated in patients complaining of isolated memory disturbances, particularly with recurrent short-lasting amnesic attacks. In all suspected cases of epilepsy, a detailed clinical history is of paramount importance, but ancillary tests including EEG and MRI could be very helpful. Transient epileptic amnesia is typically a benign and treatable condition. Future studies should investigate the exact mechanism(s) of this unique syndrome. © 2013.

  2. Conducted Transients on Spacecraft Primary Power Lines

    Science.gov (United States)

    Mc Closkey, John; Dimov, Jen

    2017-01-01

    One of the sources of potential interference on spacecraft primary power lines is that of conducted transients resulting from equipment being switched on and off of the bus. Susceptibility to such transients is addressed by some version of the CS06 requirement of MIL-STD-461462. This presentation provides a summary of the history of the CS06 requirement and test method, a basis for understanding of the sources of these transients, analysis techniques for determining their worst-case characteristics, and guidelines for minimizing their magnitudes and applying the requirement appropriately.

  3. Transient phenomena in electrical power systems

    CERN Document Server

    Venikov, V A; Higinbotham, W

    1964-01-01

    Electronics and Instrumentation, Volume 24: Transient Phenomena in Electrical Power Systems presents the methods for calculating the stability and the transient behavior of systems with forced excitation control. This book provides information pertinent to the analysis of transient phenomena in electro-mechanical systems.Organized into five chapters, this volume begins with an overview of the principal requirements in an excitation system. This text then explains the electromagnetic and electro-mechanical phenomena, taking into account the mutual action between the components of the system. Ot

  4. A Biphasic Calcium Sulphate/Hydroxyapatite Carrier Containing Bone Morphogenic Protein-2 and Zoledronic Acid Generates Bone

    DEFF Research Database (Denmark)

    Raina, Deepak Bushan; Isaksson, Hanna; Hettwer, Werner

    2016-01-01

    -the-shelf osteoinductive bone substitutes that can replace bone grafts are required. We tested the carrier properties of a biphasic, calcium sulphate and hydroxyapatite ceramic material, containing a combination of recombinant human bone morphogenic protein-2 (rhBMP-2) to induce bone, and zoledronic acid (ZA) to delay...

  5. Change in hen sciatic nerve calcium after a single oral dose of tri-o-tolyl phosphate.

    Science.gov (United States)

    Luttrell, W E; Olajos, E J; Pleban, P A

    1993-02-01

    Six trace elements were monitored in neural tissue homogenates from White Leghorn hens orally dosed with tri-o-tolyl phosphate (TOTP) or tri-m-tolyl phosphate (TMTP) (200 mg/kg). Treated birds were monitored daily for development of delayed neurotoxicity, and concentrations of calcium, copper, iron, magnesium, manganese, and zinc were measured with atomic absorption spectroscopy at the time of maximal locomotor impairment (27-35 days postdosing). TOTP-treated birds manifested motor deficit by 15 days postdosing, while hens administered TMTP exhibited no signs of delayed neurotoxicity. Total calcium content in the sciatic nerve homogenates from TOTP-dosed hens was significantly less (P < 0.05) at the time of maximal locomotor impairment, while no shifts in the other trace elements were found. Therefore, the ortho isomer of tritolylphosphate elicited symptoms of delayed neurotoxicity in the hen (i.e., organophosphorus ester-induced delayed neurotoxicity or OPIDN) and caused a decrease in total calcium content in the sciatic nerve homogenates, in contrast to effects of the meta isomer. Analysis of neural homogenates at time of maximal locomotor impairment reflected secondary events in the degradative processes, since the initial assault of TOTP happens early after administration. Therefore, at fully developed OPIDN alteration of calcium balance in sciatic nerves is an indicator of axonopathy in a degenerated nerve following chemical injury.

  6. Long-term survival of calcium phosphate-coated dental implants: a meta-analytical approach to the clinical literature

    NARCIS (Netherlands)

    Oirschot, B.A. van; Bronkhorst, E.M.; Beucken, J.J.J.P van den; Meijer, G.J.; Jansen, J.B.M.J.; Junker, R.

    2013-01-01

    BACKGROUND: Calcium phosphate ceramic coatings have the potential to compensate for challenging bone conditions such as delayed or impaired bone healing and low bone quantity or density. Thus, the increasing universal prevalence of subjects with such challenging bone conditions might be paralleled

  7. A theoretical study of factors influencing calcium-secretion coupling in a presynaptic active zone model.

    Science.gov (United States)

    Gil, Amparo; González-Vélez, Virginia; Segura, Javier; Gutiérrez, Luis Miguel

    2014-10-01

    A theoretical analysis of some of the relevant factors influencing the calcium time course and the strength and timing of release probabilities of vesicles evoked by an action potential in a calyx-type active zone is presented in this paper. In particular, our study focus on the comparison of cooperative vs non-cooperative calcium binding by the release site and the effect of the number of Ca(2+) binding sites on the calcium sensitivity for release. Regarding the comparison of cooperative and non-cooperative kinetic schemes, our simulations show that quite different results are obtained when considering one or another: a reduction in the release probability of more than a 50% is obtained when considering the cooperative kinetic scheme. Also, a delay in the average time for release appears when using this model for the calcium sensor. Our study also shows that a non-cooperative kinetic binding scheme gives rise to a well defined average calcium level for release assuming that the same kinetic constants are considered for all the sites. Our results also suggest that the central value of the calcium sensitivity for release depends on the number of binding sites N and the dissociation constant KD with a scaling law depending on NKD.

  8. Do Ca2+-adsorbing ceramics reduce the release of calcium ions from gypsum-based biomaterials?

    Science.gov (United States)

    Belcarz, Anna; Zalewska, Justyna; Pałka, Krzysztof; Hajnos, Mieczysław; Ginalska, Grazyna

    2015-02-01

    Bone implantable materials based on calcium sulfate dihydrate dissolve quickly in tissue liquids and release calcium ions at very high levels. This phenomenon induces temporary toxicity for osteoblasts, may cause local inflammation and delay the healing process. Reduction in the calcium ion release rate by gypsum could be therefore beneficial for the healing of gypsum-filled bone defects. The aim of this study concerned the potential use of calcium phosphate ceramics of various porosities for the reduction of high Ca(2+) ion release from gypsum-based materials. Highly porous ceramics failed to reduce the level of Ca(2+) ions released to the medium in a continuous flow system. However, it succeeded to shorten the period of high calcium level. It was not the phase composition but the high porosity of ceramics that was found crucial for both the shortening of the Ca(2+) release-related toxicity period and intensification of apatite deposition on the composite. Nonporous ceramics was completely ineffective for this purpose and did not show any ability to absorb calcium ions at a significant level. Moreover, according to our observations, complex studies imitating in vivo systems, rather than standard tests, are essential for the proper evaluation of implantable biomaterials. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Calcium signaling in plant cells in microgravity

    Science.gov (United States)

    Kordyum, E.

    Changes in the intracellular Ca 2 + concentration in altered gravity (microgravity and clinostating) evidence that Ca2 + signaling can play a fundamental role in biological effects of microgravity. Calcium as a second messenger is known to play a crucial role in stimulus - response coupling for many plant cellular signaling pathways. Its messenger functions are realized by transient changes in the cytosolic ion concentration induced by a variety of internal and external stimuli such as light, hormones, temperature, anoxia, salinity, and gravity. Although the first data on the changes in the calcium balance in plant cells under the influence of altered gravity have appeared in eighties, a review highlighting the performed research and the possible significance of such Ca 2 + changes in the structural and metabolic rearrangements of plant cells in altered gravity is still lacking. In this paper, an attempt was made to summarize the available experimental results and to consider some hypotheses in this field of research. It is proposed to distinguish between cell gravisensing and cell graviperception; the former is related to cell structure and metabolism stability in the gravitational field and their changes in microgravity (cells not specialized to gravity perception), the latter is related to active use of a gravitational stimulus by cells presumably specialized to gravity perception for realization of normal space orientation, growth, and vital activity (gravitropism, gravitaxis) in plants. The main experimental data concerning both redistribution of free Ca 2 + ions in plant cell organelles and the cell wall, and an increase in the intracellular Ca 2+ concentration under the influence of altered gravity are presented. Based on the gravitational decompensation hypothesis, the consequence of events occurring in gravis ensing cells not specialized to gravity perception under altered gravity are considered in the following order: changes in the cytoplasmic membrane

  10. Calcium fertilization increases the concentration of calcium in sapwood and calcium oxalate in foliage of red spruce

    Science.gov (United States)

    Kevin T. Smith; Walter C. Shortle; Jon H. Connolly; Rakesh Minocha; Jody Jellison

    2009-01-01

    Calcium cycling plays a key role in the health and productivity of red spruce forests in the northeastern US. A portion of the flowpath of calcium within forests includes translocation as Ca2+ in sapwood and accumulation as crystals of calcium oxalate in foliage. Concentrations of Ca in these tree tissues have been used as markers of...

  11. Calcium release from experimental dental materials.

    Science.gov (United States)

    Okulus, Zuzanna; Buchwald, Tomasz; Voelkel, Adam

    2016-11-01

    The calcium release from calcium phosphate-containing experimental dental restorative materials was examined. The possible correlation of ion release with initial calcium content, solubility and degree of curing (degree of conversion) of examined materials was also investigated. Calcium release was measured with the use of an ion-selective electrode in an aqueous solution. Solubility was established by the weighing method. Raman spectroscopy was applied for the determination of the degree of conversion, while initial calcium content was examined with the use of energy-dispersive spectroscopy. For examined materials, the amount of calcium released was found to be positively correlated with solubility and initial calcium content. It was also found that the degree of conversion does not affect the ability of these experimental composites to release calcium ions. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Familial hypocalciuric hypercalcemia and calcium sensing receptor

    DEFF Research Database (Denmark)

    Mrgan, Monija; Nielsen, Sanne; Brixen, Kim

    2014-01-01

    Familial hypocalciuric hypercalcemia (FHH) is a lifelong, benign autosomal dominant disease characterized by hypercalcemia, normal to increased parathyroid hormone level, and a relatively low renal calcium excretion. Inactivation of the calcium-sensing receptor in heterozygous patients results in...

  13. Vitamin D, Calcium, and Bone Health

    Science.gov (United States)

    ... Bone Health Featured Resource Find an Endocrinologist Search Vitamin D, Calcium, and Bone Health March 2012 Download ... also helps keep your bones strong. Why are vitamin D and calcium important to bone health? Vitamin ...

  14. Photoreception and signal transduction in corals: proteomic and behavioral evidence for cytoplasmic calcium as a mediator of light responsivity.

    Science.gov (United States)

    Hilton, J Daniel; Brady, Aisling K; Spaho, Skender A; Vize, Peter D

    2012-12-01

    Little is known about how corals sense and respond to light. In this report the proteome of coral is explored using 2D protein electrophoresis in two species, Montastraea cavernosa and Acropora millepora. Multiple protein species have major shifts in abundance in both species when sampled in daylight compared to corals sampled late in the night. These changes were observed both in larvae lacking zooxanthellae and in adult tissue containing zooxanthellae, including both Pacific and Caribbean corals. When larvae kept in the dark were treated with either thapsigargin or ionomycin, compounds that raise the level of cytoplasmic calcium, the night pattern of proteins shifted to the day pattern. This implies that photoreceptors responding to light elevate calcium levels and that calcium acts as the second messenger relaying light responses in corals. Corals spawn at night, and spawning can be delayed by exposure to light or pushed forward by early artificial sunsets. In a series of behavioral experiments, treatment of corals with ionomycin or thapsigargin was found to delay broadcast spawning in M. franksi, demonstrating that pharmacologically altering cytoplasmic calcium levels generates the same response as light exposure. Together these results show that the photo-responsive cells of corals detect and respond to light by altering cytoplasmic calcium levels, similarly to the transduction pathways in complex invertebrate eyes. The primacy of cytoplasmic calcium levels in light responsivity has broad implications for coral reproduction, including predicting how different species spawn at different times after sunset and how reproductive isolation is achieved during coral speciation.

  15. 21 CFR 184.1229 - Calcium stearate.

    Science.gov (United States)

    2010-04-01

    ... Specific Substances Affirmed as GRAS § 184.1229 Calcium stearate. (a) Calcium stearate (Ca(C17H35COO)2, CAS Reg. No. 1529-23-0) is the calcium salt of stearic acid derived from edible sources. It is prepared as... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium stearate. 184.1229 Section 184.1229 Food...

  16. Bioactive and Hemocompatible Calcium Sulphoaluminate Cement

    OpenAIRE

    Acuña-Gutiérrez, Iván Omar; Escobedo-Bocardo, José Concepción; Almanza-Robles, José Manuel; Cortés-Hernández, Dora Alicia; Saldívar-Ramírez, Mirna María Guadalupe; Reséndiz-Hernández, Perla Janet; Zugasti-Cruz, Alejandro

    2015-01-01

    Calcium sulphoaluminate cement (CSAC) is an attractive candidate for biomedical applications due to its appropriate mechanical properties and high calcium content. In vitro bioactivity and hemocompatibility of calcium sulphoaluminate cement were assessed. The cement was prepared from a mixture of calcium sulphoaluminate (CSA) clinker, gypsum and water. Cement samples were immersed in a simulated body fluid (SBF) at 37 °C for different periods of time (7, 14 and 21 days). The analyses of these...

  17. Calcium Balance in Chronic Kidney Disease

    OpenAIRE

    Hill Gallant, Kathleen M.; Spiegel, David M.

    2017-01-01

    Purpose of Review The kidneys play a critical role in the balance between the internal milieu and external environment. Kidney failure is known to disrupt a number of homeostatic mechanisms that control serum calcium and normal bone metabolism. However, our understanding of calcium balance throughout the stages of chronic kidney disease is limited and the concept of balance itself, especially with a cation as complex as calcium, is often misunderstood. Both negative and positive calcium balan...

  18. Calcium Balance in Chronic Kidney Disease.

    Science.gov (United States)

    Hill Gallant, Kathleen M; Spiegel, David M

    2017-06-01

    The kidneys play a critical role in the balance between the internal milieu and external environment. Kidney failure is known to disrupt a number of homeostatic mechanisms that control serum calcium and normal bone metabolism. However, our understanding of calcium balance throughout the stages of chronic kidney disease is limited and the concept of balance itself, especially with a cation as complex as calcium, is often misunderstood. Both negative and positive calcium balance have important implications in patients with chronic kidney disease, where negative balance may increase risk of osteoporosis and fracture and positive balance may increase risk of vascular calcification and cardiovascular events. Here, we examine the state of current knowledge about calcium balance in adults throughout the stages of chronic kidney disease and discuss recommendations for clinical strategies to maintain balance as well as future research needs in this area. Recent calcium balance studies in adult patients with chronic kidney disease show that neutral calcium balance is achieved with calcium intake near the recommended daily allowance. Increases in calcium through diet or supplements cause high positive calcium balance, which may put patients at risk for vascular calcification. However, heterogeneity in calcium balance exists among these patients. Given the available calcium balance data in this population, it appears clinically prudent to aim for recommended calcium intakes around 1000 mg/day to achieve neutral calcium balance and avoid adverse effects of either negative or positive calcium balance. Assessment of patients' dietary calcium intake could further equip clinicians to make individualized recommendations for meeting recommended intakes.

  19. Electrochemical Induced Calcium Phosphate Precipitation

    NARCIS (Netherlands)

    Lei, Yang; Song, Bingnan; Weijden, van der Renata D.; Saakes, M.; Buisman, Cees J.N.

    2017-01-01

    Phosphorus (P) is an essential nutrient for living organisms and cannot be replaced or substituted. In this paper, we present a simple yet efficient membrane free electrochemical system for P removal and recovery as calcium phosphate (CaP). This method relies on in situ formation of hydroxide

  20. Detection of Transient Signals in Doppler Spectra

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Signal processing is used to detect transient signals in the presence of noise. Two embodiments are disclosed. In both embodiments, the time series from a remote...

  1. Prony Analysis for Power System Transient Harmonics

    Directory of Open Access Journals (Sweden)

    David Cartes

    2007-01-01

    Full Text Available Proliferation of nonlinear loads in power systems has increased harmonic pollution and deteriorated power quality. Not required to have prior knowledge of existing harmonics, Prony analysis detects frequencies, magnitudes, phases, and especially damping factors of exponential decaying or growing transient harmonics. In this paper, Prony analysis is implemented to supervise power system transient harmonics, or time-varying harmonics. Further, to improve power quality when transient harmonics appear, the dominant harmonics identified from Prony analysis are used as the harmonic reference for harmonic selective active filters. Simulation results of two test systems during transformer energizing and induction motor starting confirm the effectiveness of the Prony analysis in supervising and canceling power system transient harmonics.

  2. 21 CFR 582.7187 - Calcium alginate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium alginate. 582.7187 Section 582.7187 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Calcium alginate. (a) Product. Calcium alginate. (b) Conditions of use. This substance is generally...

  3. Abnormalities of serum calcium and magnesium

    Science.gov (United States)

    Neonatal hypocalcemia is defined as a total serum calcium concentration of <7 mg/dL or an ionized calcium concentration of <4 mg/dL (1mmol/L). In very low birth weight (VLBW) infants, ionized calcium values of 0.8 to 1 mmol/L are common and not usually associated with clinical symptoms. In larger in...

  4. Modularized study of human calcium signalling pathway

    Indian Academy of Sciences (India)

    PRAKASH KUMAR

    When there is an extracellular change, cells get the message either by introduction of calcium ions into ... as it precipitates phosphate, the established energy currency of cells. Prolonged high intracellular calcium ... trigger proteins upon binding with free calcium ion(s) change their confirmation to modulate enzymes and ion ...

  5. 21 CFR 582.1191 - Calcium carbonate.

    Science.gov (United States)

    2010-04-01

    ... Additives § 582.1191 Calcium carbonate. (a) Product. Calcium carbonate. (b) Conditions of use. This... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium carbonate. 582.1191 Section 582.1191 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL...

  6. 21 CFR 582.5191 - Calcium carbonate.

    Science.gov (United States)

    2010-04-01

    ... Supplements 1 § 582.5191 Calcium carbonate. (a) Product. Calcium carbonate. (b) Conditions of use. This... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium carbonate. 582.5191 Section 582.5191 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL...

  7. Mechanism of store-operated calcium entry

    Indian Academy of Sciences (India)

    Activation of receptors coupled to the phospholipase C/IP3 signalling pathway results in a rapid release of calcium from its intracellular stores, eventually leading to depletion of these stores. Calcium store depletion triggers an influx of extracellular calcium across the plasma membrane, a mechanism known as the ...

  8. Mitochondrial Calcium Sparkles Light Up Astrocytes.

    Science.gov (United States)

    MacVicar, Brian A; Ko, Rebecca W Y

    2017-02-27

    Discrete calcium signals in the fine processes of astrocytes are a recent discovery and a new mystery. In a recent issue of Neuron, Agarwal et al. (2017) report that calcium efflux from mitochondria during brief openings of the mitochondrial permeability transition pore (mPTP) contribute to calcium microdomains. Crown Copyright © 2017. Published by Elsevier Inc. All rights reserved.

  9. 21 CFR 182.1217 - Calcium phosphate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium phosphate. 182.1217 Section 182.1217 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Substances § 182.1217 Calcium phosphate. (a) Product. Calcium phosphate (mono-, di-, and tribasic). (b...

  10. 21 CFR 582.1217 - Calcium phosphate.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium phosphate. 582.1217 Section 582.1217 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1217 Calcium phosphate. (a) Product. Calcium phosphate (mono-, di-, and tribasic). (b...

  11. ORIGINAL ARTICLES Calcium supplementation to prevent pre ...

    African Journals Online (AJOL)

    ORIGINAL ARTICLES. Calcium supplementation to prevent pre-eclampsia - a systematic review. G J Hofmeyr, A Roodt, A N Atallah, L Duley. Background. Calcium supplementation during pregnancy may prevent high blood pressure and preterm labour. Objective. To assess the effects of calcium supplementation.

  12. Transient analysis of a queue with queue-length dependent MAP and its application to SS7 network

    Directory of Open Access Journals (Sweden)

    Bong Dae Choi

    1999-01-01

    Full Text Available We analyze the transient behavior of a Markovian arrival queue with congestion control based on a double of thresholds, where the arrival process is a queue-length dependent Markovian arrival process. We consider Markov chain embedded at arrival epochs and derive the one-step transition probabilities. From these results, we obtain the mean delay and the loss probability of the nth arrival packet. Before we study this complex model, first we give a transient analysis of an MAP/M/1 queueing system without congestion control at arrival epochs. We apply our result to a signaling system No. 7 network with a congestion control based on thresholds.

  13. Transient Analysis of Manufacturing Systems Performance

    OpenAIRE

    Narahari, Y.; Viswanadham, N

    1994-01-01

    Studies in performance evaluation of automated manufacturing systems, using simulation or analytical models,have always emphasized steady-state or equilibrium performance in preference to transient performance. In this study, we present several situations in manufacturing systems where transient analysis is very important. Manufacturing systems and models in which such situations arise include: systems with failure states and deadlocks, unstable queueing systems, and systems with fluctuating ...

  14. Cable system transients theory, modeling and simulation

    CERN Document Server

    Ametani, Akihiro; Nagaoka, Naoto

    2015-01-01

    A systematic and comprehensive introduction to electromagnetic transient in cable systems, written by the internationally renowned pioneer in this field Presents a systematic and comprehensive introduction to electromagnetic transient in cable systems Written by the internationally renowned pioneer in the field Thorough coverage of the state of the art on the topic, presented in a well-organized, logical style, from fundamentals and practical applications A companion website is available

  15. Delay of Vehicle Motion in Traffic Dynamics

    CERN Document Server

    Bando, M; Nakanishi, K; Nakayama, A; Bando, Masako; Hasebe, Katsuya; Nakanishi, Ken; Nakayama, Akihiro

    1996-01-01

    We demonstrate that in Optimal Velocity Model (OVM) delay times of vehicles coming from the dynamical equation of motion of OVM almost explain the order of delay times observed in actual traffic flows without introducing explicit delay times. Delay times in various cases are estimated: the case of a leader vehicle and its follower, a queue of vehicles controlled by traffic lights and many-vehicle case of highway traffic flow. The remarkable result is that in most of the situation for which we can make a reasonable definition of a delay time, the obtained delay time is of order 1 second.

  16. Calcium Orthophosphate-Based Bioceramics

    Directory of Open Access Journals (Sweden)

    Sergey V. Dorozhkin

    2013-09-01

    Full Text Available Various types of grafts have been traditionally used to restore damaged bones. In the late 1960s, a strong interest was raised in studying ceramics as potential bone grafts due to their biomechanical properties. A bit later, such synthetic biomaterials were called bioceramics. In principle, bioceramics can be prepared from diverse materials but this review is limited to calcium orthophosphate-based formulations only, which possess the specific advantages due to the chemical similarity to mammalian bones and teeth. During the past 40 years, there have been a number of important achievements in this field. Namely, after the initial development of bioceramics that was just tolerated in the physiological environment, an emphasis was shifted towards the formulations able to form direct chemical bonds with the adjacent bones. Afterwards, by the structural and compositional controls, it became possible to choose whether the calcium orthophosphate-based implants remain biologically stable once incorporated into the skeletal structure or whether they were resorbed over time. At the turn of the millennium, a new concept of regenerative bioceramics was developed and such formulations became an integrated part of the tissue engineering approach. Now calcium orthophosphate scaffolds are designed to induce bone formation and vascularization. These scaffolds are often porous and harbor different biomolecules and/or cells. Therefore, current biomedical applications of calcium orthophosphate bioceramics include bone augmentations, artificial bone grafts, maxillofacial reconstruction, spinal fusion, periodontal disease repairs and bone fillers after tumor surgery. Perspective future applications comprise drug delivery and tissue engineering purposes because calcium orthophosphates appear to be promising carriers of growth factors, bioactive peptides and various types of cells.

  17. Minimum Delay Moving Object Detection

    KAUST Repository

    Lao, Dong

    2017-01-08

    We present a general framework and method for detection of an object in a video based on apparent motion. The object moves relative to background motion at some unknown time in the video, and the goal is to detect and segment the object as soon it moves in an online manner. Due to unreliability of motion between frames, more than two frames are needed to reliably detect the object. Our method is designed to detect the object(s) with minimum delay, i.e., frames after the object moves, constraining the false alarms. Experiments on a new extensive dataset for moving object detection show that our method achieves less delay for all false alarm constraints than existing state-of-the-art.

  18. Minimum Delay Moving Object Detection

    KAUST Repository

    Lao, Dong

    2017-11-09

    We present a general framework and method for detection of an object in a video based on apparent motion. The object moves relative to background motion at some unknown time in the video, and the goal is to detect and segment the object as soon it moves in an online manner. Due to unreliability of motion between frames, more than two frames are needed to reliably detect the object. Our method is designed to detect the object(s) with minimum delay, i.e., frames after the object moves, constraining the false alarms. Experiments on a new extensive dataset for moving object detection show that our method achieves less delay for all false alarm constraints than existing state-of-the-art.

  19. Air congestion delay: a review

    Directory of Open Access Journals (Sweden)

    Daniel Alberto Pamplona

    2016-04-01

    Full Text Available This article is a literature review of the air congestion delay and its costs. Air congestion is a worldwide problem. Its existence brings costs for airlines and discomfort for passengers. With the increasing demand for air transport, the study of air congestion has attracted the attention of many researchers around the world. The cause for the delays is erroneously attributed only to the lack of infrastructure investments. The literature review shows that other factors such as population growth, increasing standards of living, lack of operational planning and environmental issues exercise decisive influence. Several studies have been conducted in order to analyze and propose solutions to this problem that affects society as a whole.

  20. Green fluorescent genetically encoded calcium indicator based on calmodulin/M13-peptide from fungi.

    Directory of Open Access Journals (Sweden)

    Natalia V Barykina

    Full Text Available Currently available genetically encoded calcium indicators (GECIs utilize calmodulins (CaMs or troponin C from metazoa such as mammals, birds, and teleosts, as calcium-binding domains. The amino acid sequences of the metazoan calcium-binding domains are highly conserved, which may limit the range of the GECI key parameters and cause undesired interactions with the intracellular environment in mammalian cells. Here we have used fungi, evolutionary distinct organisms, to derive CaM and its binding partner domains and design new GECI with improved properties. We applied iterative rounds of molecular evolution to develop FGCaMP, a novel green calcium indicator. It includes the circularly permuted version of the enhanced green fluorescent protein (EGFP sandwiched between the fungal CaM and a fragment of CaM-dependent kinase. FGCaMP is an excitation-ratiometric indicator that has a positive and an inverted fluorescence response to calcium ions when excited at 488 and 405 nm, respectively. Compared with the GCaMP6s indicator in vitro, FGCaMP has a similar brightness at 488 nm excitation, 7-fold higher brightness at 405 nm excitation, and 1.3-fold faster calcium ion dissociation kinetics. Using site-directed mutagenesis, we generated variants of FGCaMP with improved binding affinity to calcium ions and increased the magnitude of FGCaMP fluorescence response to low calcium ion concentrations. Using FGCaMP, we have successfully visualized calcium transients in cultured mammalian cells. In contrast to the limited mobility of GCaMP6s and G-GECO1.2 indicators, FGCaMP exhibits practically 100% molecular mobility at physiological concentrations of calcium ion in mammalian cells, as determined by photobleaching experiments with fluorescence recovery. We have successfully monitored the calcium dynamics during spontaneous activity of neuronal cultures using FGCaMP and utilized whole-cell patch clamp recordings to further characterize its behavior in neurons