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Sample records for events precede calcium

  1. ‘Trigger’ Events Precede Calcium Puffs in Xenopus Oocytes

    PubMed Central

    Rose, Heather J.; Dargan, Sheila; Shuai, Jianwei; Parker, Ian

    2006-01-01

    The liberation of calcium ions sequestered in the endoplasmic reticulum through inositol 1,4,5-trisphosphate receptors/channels (IP3Rs) results in a spatiotemporal hierarchy of calcium signaling events that range from single-channel openings to local Ca2+ puffs believed to arise from several to tens of clustered IP3Rs to global calcium waves. Using high-resolution confocal linescan imaging and a sensitive Ca2+ indicator dye (fluo-4-dextran), we show that puffs are often preceded by small, transient Ca2+ elevations that we christen “trigger events”. The magnitude of triggers is consistent with their arising from the opening of a single IP3 receptor/channel, and we propose that they initiate puffs by recruiting neighboring IP3Rs within the cluster by a regenerative process of Ca2+-induced Ca2+ release. Puff amplitudes (fluorescence ratio change) are on average ∼6 times greater than that of the triggers, suggesting that at least six IP3Rs may simultaneously be open during a puff. Trigger events have average durations of ∼12 ms, as compared to 19 ms for the mean rise time of puffs, and their spatial extent is ∼3 times smaller than puffs (respective widths at half peak amplitude 0.6 and 1.6 μm). All these parameters were relatively independent of IP3 concentration, although the proportion of puffs showing resolved triggers was greatest (∼80%) at low [IP3]. Because Ca2+ puffs constitute the building blocks from which cellular IP3-mediated Ca2+ signals are constructed, the events that initiate them are likely to be of fundamental importance for cell signaling. Moreover, the trigger events provide a useful yardstick by which to derive information regarding the number and spatial arrangement of IP3Rs within clusters. PMID:16980363

  2. Life events and difficulties preceding stroke.

    PubMed Central

    House, A; Dennis, M; Mogridge, L; Hawton, K; Warlow, C

    1990-01-01

    Life events and difficulties were recorded for the year before stroke, using a standardised semi-structured interview, in 113 surviving patients seen after their first ever in a lifetime stroke. An age and sex-matched control group (n = 109) was also interviewed about the preceding year. The stroke patients reported fewer non-threatening events and events with only a short-term threat, while difficulties were reported with equal frequency by the two groups. However, events which were severely threatening in the long-term were significantly more common in the stroke patients (in the 52 weeks before stroke 26% versus 13%, odds ratio 2.3, 95% confidence interval 1.1-4.9). The increased rate was apparent throughout the year and not just in the weeks immediately before stroke onset. The number of stroke patients experiencing severe events in the follow up year fell to the level found in the control group. Recognised risk factors for stroke were found equally in those patients with and without severe events before onset, except that hypertension was rather less common in the patients who had experienced a severe event. It therefore appears that severe life events may be one of the determinants of stroke onset. PMID:2292691

  3. Differences between the events preceding spina bifida and anencephaly.

    PubMed Central

    James, W H

    1981-01-01

    It is usually held that there is a time continuum in the formation of monoxygotic (MZ) twins which is indexed by their placentation, running from dichorionic to monochorionic diamniotic to monochorionic monoamniotic and conjoined pairs. There is good evidence that this continuum is characterised by a continuum of predisposition to anencephaly, slightly raised in dichorionic pairs but very high in some sorts of conjoined pairs. Although MZ twins, especially monoamniotic and conjoined pairs, are peculiarly liable to anencephaly, they are not particularly susceptible to spina bifida. Among twin pairs concordant for anencephaly or spina bifida, there are strikingly few concordant in the sense of one twin having anencephaly and the other spina bifida, in contrast with the numbers of pairs concordant for the same malformation. The prevalence of anencephaly in double monsters varies with the type of monster, being high in diprosopus. These findings may be explained by the timing of embryonic events. PMID:7019447

  4. Calcium ion currents mediating oocyte maturation events

    PubMed Central

    Tosti, Elisabetta

    2006-01-01

    During maturation, the last phase of oogenesis, the oocyte undergoes several changes which prepare it to be ovulated and fertilized. Immature oocytes are arrested in the first meiotic process prophase, that is morphologically identified by a germinal vesicle. The removal of the first meiotic block marks the initiation of maturation. Although a large number of molecules are involved in complex sequences of events, there is evidence that a calcium increase plays a pivotal role in meiosis re-initiation. It is well established that, during this process, calcium is released from the intracellular stores, whereas less is known on the role of external calcium entering the cell through the plasma membrane ion channels. This review is focused on the functional role of calcium currents during oocyte maturation in all the species, from invertebrates to mammals. The emerging role of specific L-type calcium channels will be discussed. PMID:16684344

  5. Kickoff to Conflict: A Sequence Analysis of Intra-State Conflict-Preceding Event Structures

    PubMed Central

    D'Orazio, Vito; Yonamine, James E.

    2015-01-01

    While many studies have suggested or assumed that the periods preceding the onset of intra-state conflict are similar across time and space, few have empirically tested this proposition. Using the Integrated Crisis Early Warning System's domestic event data in Asia from 1998–2010, we subject this proposition to empirical analysis. We code the similarity of government-rebel interactions in sequences preceding the onset of intra-state conflict to those preceding further periods of peace using three different metrics: Euclidean, Levenshtein, and mutual information. These scores are then used as predictors in a bivariate logistic regression to forecast whether we are likely to observe conflict in neither, one, or both of the states. We find that our model accurately classifies cases where both sequences precede peace, but struggles to distinguish between cases in which one sequence escalates to conflict and where both sequences escalate to conflict. These findings empirically suggest that generalizable patterns exist between event sequences that precede peace. PMID:25951105

  6. Patterns of Life Events Preceding the Suicide in Rural Young Chinese: A Case Control Study1

    PubMed Central

    Zhang, Jie; Ma, Zhenyu

    2012-01-01

    Background Previous studies on the Chinese suicide found some life events prior to the suicide different from those in the West, but there is a lack of summary of the Chinese life event patterns to better understand the effects of the social structure on Chinese suicide. Aim We tried to identify the life events that precede the Chinese rural youth suicides and compare them with what found in the West, so as to find the patterns that are particularly true in the Chinese culture contexts. Methods Suicide cases were investigated with a psychological autopsy study in rural China, and local community living controls were also interviewed with the same protocol. Results We collapsed 64 negative life events into six categories: (1) Marriage/Love, (2) Family/Home, (3) Work/Business, (4) Health/Hospital, (5) Law/Legal, (6) Friend/Relationship. About 92.3% of the suicides studied had experienced at least one type of negative life events. The three most common negative life events categories in the past one year were Family/Home (60.7%), Health/Hospital (53.8%) and Marriage/Love (51.3%) in the rural young suicide victims. Conclusions Among the negative life events, those related to family relations, love affairs, and marital issues were most likely to precede a suicide of rural suicides in China, and it is especially true of rural young women. Family is an important social institution in rural China for suicide prevention efforts. PMID:22595373

  7. Intense foreshocks and a slow slip event preceded the 2014 Iquique Mw 8.1 earthquake.

    PubMed

    Ruiz, S; Metois, M; Fuenzalida, A; Ruiz, J; Leyton, F; Grandin, R; Vigny, C; Madariaga, R; Campos, J

    2014-09-01

    The subduction zone in northern Chile is a well-identified seismic gap that last ruptured in 1877. The moment magnitude (Mw) 8.1 Iquique earthquake of 1 April 2014 broke a highly coupled portion of this gap. To understand the seismicity preceding this event, we studied the location and mechanisms of the foreshocks and computed Global Positioning System (GPS) time series at stations located on shore. Seismicity off the coast of Iquique started to increase in January 2014. After 16 March, several Mw > 6 events occurred near the low-coupled zone. These events migrated northward for ~50 kilometers until the 1 April earthquake occurred. On 16 March, on-shore continuous GPS stations detected a westward motion that we model as a slow slip event situated in the same area where the mainshock occurred. PMID:25061132

  8. A very long-term transient event preceding the 2011 Tohoku earthquake.

    PubMed

    Yokota, Yusuke; Koketsu, Kazuki

    2015-01-01

    Geodetic transients have been observed in various subduction zones. The 2011 Tohoku earthquake occurred in one of the most active subduction zones globally, the Japan Trench subduction zone (JTSZ). However, no geodetic transient (except afterslip and so on) had been reported in the JTSZ before the Tohoku earthquake. Here we show that a large transient event, with duration longer than any reported previously, occurred in the JTSZ preceding the Tohoku earthquake. We calculate tectonic deformations at Global Positioning System stations along the JTSZ by removing the effects of nearby M(w) 6-8 earthquakes. We identify temporal changes in these deformations, deriving 9-year deviation records from regular deformations due to slip deficit at the plate boundary. We perform an inversion of the deviations to obtain the source model of their root event. The relationship between the obtained transient event and Tohoku earthquake is shown through Coulomb stress change and seismic supercycle simulation. PMID:25562609

  9. Fluoride concentrations in dental plaque and saliva after the use of a fluoride dentifrice preceded by a calcium lactate rinse.

    PubMed

    Pessan, Juliano P; Sicca, Cristina M; de Souza, Tatiana S; da Silva, Salete M B; Whitford, Gary M; Buzalaf, Marília A R

    2006-12-01

    Plaque fluoride concentrations ([F]) are directly related to plaque calcium concentrations [Ca]. Attempts to increase plaque F uptake from dentifrices or rinses have used methods designed to increase plaque [Ca] but with inconsistent results. This double-blind, double-crossover study tested the effect of a 150 mM calcium lactate rinse used prior to brushing with placebo or fluoridated dentifrices (1030 p.p.m. as NaF) on plaque and salivary [F] and [Ca]. Sixteen children (8-10 yr of age) were randomly assigned to four different groups according to the four treatments (placebo dentifrice or fluoridated dentifrice preceded by calcium lactate or deionized water prerinses). Plaque and saliva were collected 1 and 12 h after brushing on day 7 after starting to use the dentifrices. F was determined using the electrode and Ca was determined using atomic absorption spectrometry. Plaque and salivary [Ca] were not significantly increased after use of the calcium lactate prerinse, except for plaque [Ca] 1 h after the use of the placebo dentifrice. A significant increase in salivary [F] was associated with the calcium lactate prerinse only at 1 h after the use of the fluoridated dentifrice. The the calcium lactate prerinse did not significantly affect plaque [F] under any condition. PMID:17184230

  10. Perigenual anterior cingulate event-related potential precedes stop signal errors

    PubMed Central

    Chang, Andrew; Chen, Chien-Chung; Li, Hsin-Hung; Li, Chiang-Shan R.

    2015-01-01

    Momentary lapses in attention disrupt goal-directed behavior. Attentional lapse has been associated with increased “default-mode” network (DMN) activity. In our previous fMRI study of a stop signal task (SST), greater activation of the perigenual anterior cingulate cortex (pgACC) – an important node of the DMN – predicts stop signal errors. In event-related potential (ERP) studies, the amplitude of an error-preceding positivity (EPP) also predicts response error. However, it is not clear whether the EPP originates from DMN regions. Here, we combined high-density array EEG and an SST to examine response-locked ERPs of error preceding trials in twenty young adult participants. The results showed an EPP in go trials that preceded stop error than stop success trials. Importantly, source modeling identified the origin of the EPP in the pgACC. By employing a bootstrapping procedure, we further confirmed that pgACC rather than the dorsal ACC as the source provides a better fit to the EPP. Together, these results suggest that attentional lapse in association with EPP in the pgACC anticipates failure in response inhibition. PMID:25700955

  11. Automated Discovery and Modeling of Sequential Patterns Preceding Events of Interest

    NASA Technical Reports Server (NTRS)

    Rohloff, Kurt

    2010-01-01

    The integration of emerging data manipulation technologies has enabled a paradigm shift in practitioners' abilities to understand and anticipate events of interest in complex systems. Example events of interest include outbreaks of socio-political violence in nation-states. Rather than relying on human-centric modeling efforts that are limited by the availability of SMEs, automated data processing technologies has enabled the development of innovative automated complex system modeling and predictive analysis technologies. We introduce one such emerging modeling technology - the sequential pattern methodology. We have applied the sequential pattern methodology to automatically identify patterns of observed behavior that precede outbreaks of socio-political violence such as riots, rebellions and coups in nation-states. The sequential pattern methodology is a groundbreaking approach to automated complex system model discovery because it generates easily interpretable patterns based on direct observations of sampled factor data for a deeper understanding of societal behaviors that is tolerant of observation noise and missing data. The discovered patterns are simple to interpret and mimic human's identifications of observed trends in temporal data. Discovered patterns also provide an automated forecasting ability: we discuss an example of using discovered patterns coupled with a rich data environment to forecast various types of socio-political violence in nation-states.

  12. Calcium oscillations and T-wave lability precede ventricular arrhythmias in acquired long QT type 2

    PubMed Central

    Němec, Jan; Kim, Jong J.; Gabris, Beth; Salama, Guy

    2010-01-01

    Background Alternans of intracellular Ca2+ (Cai) underlies T-wave alternans, a predictor of cardiac arrhythmias. A related phenomenon, T-Wave Lability (TWL), precedes Torsade de Pointes (TdP) in patients and animal models with impaired repolarization. However, the role of Cai in TWL remains unexplored. Methods Action potentials (APs) and Cai transients, (CaTs) were mapped optically from paced Langendorff female rabbit hearts (n=8) at 1.2s cycle length, after AV node ablation. Hearts were perfused with normal Tyrode's solution then with dofetilide (0.5 μM) and reduced [K+] (2 mM) and [Mg2+] (0.5 mM) to elicit long QT type 2 (LQT2). Lability of EKG, voltage and Cai signals were evaluated during regular paced rhythm, before and after dofetilide perfusion. Results In LQT2, lability of Cai, voltage and EKG signals increased during paced rhythm, before the appearance of early afterdepolarizations (EADs). LQT2 resulted in AP prolongation and multiple (1-3) additional Cai upstrokes, while APs remained monophasic. When EADs appeared, Cai rose before voltage upstrokes at the origins of propagating EADs. Interventions (i.e. ryanodine and thapsigargin, n=3 or low [Ca]o and nifedipine, n=4) that suppressed Cai oscillations also abolished EADs. Conclusions In LQT2, Cai oscillations (CaiO) precede EADs by minutes, indicating that they result from spontaneous sarcoplasmic reticulum Ca2+ release rather than spontaneous ICaL reactivation. CaiO likely produce oscillations of Na/Ca exchange current, INCX. Depolarizing INCX during the AP plateau contributes to the generation of EADs by re-activating Ca2+-channels that have recovered from inactivation. TWL reflects CaTs and APs lability that occur before EADs and TdP. PMID:20599524

  13. Seagrass Proliferation Precedes Mortality during Hypo-Salinity Events: A Stress-Induced Morphometric Response

    PubMed Central

    Collier, Catherine J.; Villacorta-Rath, Cecilia; van Dijk, Kor-jent; Takahashi, Miwa; Waycott, Michelle

    2014-01-01

    Halophytes, such as seagrasses, predominantly form habitats in coastal and estuarine areas. These habitats can be seasonally exposed to hypo-salinity events during watershed runoff exposing them to dramatic salinity shifts and osmotic shock. The manifestation of this osmotic shock on seagrass morphology and phenology was tested in three Indo-Pacific seagrass species, Halophila ovalis, Halodule uninervis and Zostera muelleri, to hypo-salinity ranging from 3 to 36 PSU at 3 PSU increments for 10 weeks. All three species had broad salinity tolerance but demonstrated a moderate hypo-salinity stress response – analogous to a stress induced morphometric response (SIMR). Shoot proliferation occurred at salinities <30 PSU, with the largest increases, up to 400% increase in shoot density, occurring at the sub-lethal salinities <15 PSU, with the specific salinity associated with peak shoot density being variable among species. Resources were not diverted away from leaf growth or shoot development to support the new shoot production. However, at sub-lethal salinities where shoots proliferated, flowering was severely reduced for H. ovalis, the only species to flower during this experiment, demonstrating a diversion of resources away from sexual reproduction to support the investment in new shoots. This SIMR response preceded mortality, which occurred at 3 PSU for H. ovalis and 6 PSU for H. uninervis, while complete mortality was not reached for Z. muelleri. This is the first study to identify a SIMR in seagrasses, being detectable due to the fine resolution of salinity treatments tested. The detection of SIMR demonstrates the need for caution in interpreting in-situ changes in shoot density as shoot proliferation could be interpreted as a healthy or positive plant response to environmental conditions, when in fact it could signal pre-mortality stress. PMID:24705377

  14. Seagrass proliferation precedes mortality during hypo-salinity events: a stress-induced morphometric response.

    PubMed

    Collier, Catherine J; Villacorta-Rath, Cecilia; van Dijk, Kor-jent; Takahashi, Miwa; Waycott, Michelle

    2014-01-01

    Halophytes, such as seagrasses, predominantly form habitats in coastal and estuarine areas. These habitats can be seasonally exposed to hypo-salinity events during watershed runoff exposing them to dramatic salinity shifts and osmotic shock. The manifestation of this osmotic shock on seagrass morphology and phenology was tested in three Indo-Pacific seagrass species, Halophila ovalis, Halodule uninervis and Zostera muelleri, to hypo-salinity ranging from 3 to 36 PSU at 3 PSU increments for 10 weeks. All three species had broad salinity tolerance but demonstrated a moderate hypo-salinity stress response--analogous to a stress induced morphometric response (SIMR). Shoot proliferation occurred at salinities <30 PSU, with the largest increases, up to 400% increase in shoot density, occurring at the sub-lethal salinities <15 PSU, with the specific salinity associated with peak shoot density being variable among species. Resources were not diverted away from leaf growth or shoot development to support the new shoot production. However, at sub-lethal salinities where shoots proliferated, flowering was severely reduced for H. ovalis, the only species to flower during this experiment, demonstrating a diversion of resources away from sexual reproduction to support the investment in new shoots. This SIMR response preceded mortality, which occurred at 3 PSU for H. ovalis and 6 PSU for H. uninervis, while complete mortality was not reached for Z. muelleri. This is the first study to identify a SIMR in seagrasses, being detectable due to the fine resolution of salinity treatments tested. The detection of SIMR demonstrates the need for caution in interpreting in-situ changes in shoot density as shoot proliferation could be interpreted as a healthy or positive plant response to environmental conditions, when in fact it could signal pre-mortality stress. PMID:24705377

  15. Survey of DMSP Charging Events During the Period Preceding Cycle 23 Solar Maximum

    NASA Technical Reports Server (NTRS)

    Parker, Linda Neergaard; Minow, Joseph I.

    2013-01-01

    It has been well established that POLAR orbiting satellites can see mild to severe charging levels during solar minimum conditions (Frooninckx and Sojka, 1992, Anderson and Koons, 1996, Anderson, 2012). However, spacecraft operations during solar maximum cannot be considered safe from auroral charging. Recently, we have seen examples of high level charging during the recent approach to solar maximum. We present here a survey of charging events seen by the Defense Meteorological Satellite Program (DMSP) satellites (F16, F17) during the solstices of 2011 and 2012. In this survey, we summarize the condition necessary for charging to occur in this environment, we describe how the lower than normal maximum conditions are conducive to the environment conditions necessary for charging in the POLAR orbit, and we show examples of the more extreme charging events, sometimes exceeding 1 kV, during this time period. We also show examples of other interesting phenomenological events seen in the DMSP data, but which are not considered surface charging events, and discuss the differences.

  16. Predicting errors from patterns of event-related potentials preceding an overt response.

    PubMed

    Bode, Stefan; Stahl, Jutta

    2014-12-01

    Everyday actions often require fast and efficient error detection and error correction. For this, the brain has to accumulate evidence for errors as soon as it becomes available. This study used multivariate pattern classification techniques for event-related potentials to track the accumulation of error-related brain activity before an overt response was made. Upcoming errors in a digit-flanker task could be predicted after the initiation of an erroneous motor response, ∼90ms before response execution. Channels over motor and parieto-occipital cortices were most important for error prediction, suggesting ongoing perceptual analyses and comparisons of initiated and appropriate motor programmes. Lower response force on error trials as compared to correct trials was observed, which indicates that this early error information was used for attempts to correct for errors before the overt response was made. In summary, our results suggest an early, automatic accumulation of error-related information, providing input for fast correction processes. PMID:25450163

  17. Brain structural correlates of obsessive-compulsive disorder with and without preceding stressful life events.

    PubMed

    Real, E; Subirà, M; Alonso, P; Segalàs, C; Labad, J; Orfila, C; López-Solà, C; Martínez-Zalacaín, I; Via, E; Cardoner, N; Jiménez-Murcia, S; Soriano-Mas, C; Menchón, J M

    2016-08-01

    Objectives There is growing evidence supporting a role for stressful life events (SLEs) at obsessive-compulsive disorder (OCD) onset, but neurobiological correlates of such effect are not known. We evaluated regional grey matter (GM) changes associated with the presence/absence of SLEs at OCD onset. Methods One hundred and twenty-four OCD patients and 112 healthy controls were recruited. Patients were split into two groups according to the presence (n = 56) or absence (n = 68) of SLEs at disorder's onset. A structural magnetic resonance image was acquired for each participant and pre-processed with Statistical Parametric Mapping software (SPM8) to obtain a volume-modulated GM map. Between-group differences in sociodemographic, clinical and whole-brain regional GM volumes were assessed. Results SLEs were associated with female sex, later age at disorder's onset, more contamination/cleaning and less hoarding symptoms. In comparison with controls, patients without SLEs showed GM volume increases in bilateral dorsal putamen and the central tegmental tract of the brainstem. By contrast, patients with SLEs showed specific GM volume increases in the right anterior cerebellum. Conclusions Our findings support the idea that neuroanatomical alterations of OCD patients partially depend on the presence of SLEs at disorder's onset. PMID:26784523

  18. Event-related power modulations of brain activity preceding visually guided saccades.

    PubMed

    Brignani, Debora; Maioli, Claudio; Maria Rossini, Paolo; Miniussi, Carlo

    2007-03-01

    To analyze the characteristics of the event-related desynchronization (ERD) and synchronization (ERS) of cortical rhythms during the preparation and execution of a lateralized eye movement, EEG was recorded in normal subjects during a visually guided task. Alpha and beta bands were investigated in three temporal intervals: a sensory period, a delay period and a saccade preparation period time locked with saccade onset. Modulations of ERD/ERS power, coupled with the task, reached the largest amplitudes over the frontal and parieto-occipital regions. Differences of oscillatory activity in the alpha bands revealed an intriguing pattern of asymmetry in parieto-occipital areas. Rightward saccades induced a larger desynchronization with respect to the leftward saccades in the left hemisphere, but not in the right. If representative, these findings are congruent to the established right-hemisphere dominance of the brain areas that direct attention. Moreover differences between the two alpha types emerged in the frontal areas before and during the saccade preparation periods, indicative of differential engagement of these areas depending on the task demands. In conclusion, the present approach shows that planning eye movements is linked with covert orienting of spatial attention and may supply a useful method for studying eye movements and selective attention-related processes. PMID:17196943

  19. Drop in endo/sarcoplasmic calcium precedes the unfolded protein response in Brefeldin A-treated vascular smooth muscle cells.

    PubMed

    Ziomek, Gabriela; van Breemen, Cornelis; Esfandiarei, Mitra

    2015-10-01

    The present study addresses the causal relationship between induction of endo/sarcoplasmic reticulum stress and dysregulation of calcium transport, while examining whether the most widely-used experimental endo/sarcoplasmic reticulum stressors can be considered appropriate for elucidating underlying cellular mechanisms involved during the progression of the unfolded protein response in vascular smooth muscle cells. Brefeldin A is most commonly cited as inducing the stress response through an accumulation of unfolded proteins in the lumen as a result of a blockage of protein transport from the endo/sarcoplasmic reticulum to the Golgi apparatus. We investigated the effects of Brefeldin A on cellular calcium regulation during the the unfolded protein response in cultured rat vascular smooth muscle cells. Acute exposure of cells to Brefeldin A caused a small transient increase in cytoplasmic calcium, which did not cause a significant decrease in endo/sarcoplasmic reticulum calcium content. However, over the time course of 0-12 h post-treatment with Brefeldin A, we observed that the endo/sarcoplasmic reticulum of vascular smooth muscle cells exhibited an approximate fifty percent decrease in calcium concentration after the first hour of exposure, which is maintained over the next eleven hours, whereas concentrations of unfolded protein response markers only began to increase significantly around nine to twelve hours post-treatment. We have concluded that the endo/sarcoplasmic reticulum calcium drop, which up to now, has been considered as a characteristic of the late onset of cellular stress response, occurs prior to the initiation of the unfolded protein response, rather than as a result of its many corrective pathways. PMID:26172080

  20. TP53 mutations are early events in chronic lymphocytic leukemia disease progression and precede evolution to complex karyotypes.

    PubMed

    Lazarian, Gregory; Tausch, Eugen; Eclache, Virginie; Sebaa, Amel; Bianchi, Vincent; Letestu, Remi; Collon, Jean-Francois; Lefebvre, Valerie; Gardano, Laura; Varin-Blank, Nadine; Soussi, Thierry; Stilgenbauer, Stephen; Cymbalista, Florence; Baran-Marszak, Fanny

    2016-10-15

    TP53 abnormalities lead to resistance to purine analogues and are found in over 40% of patients with refractory chronic lymphocytic leukemia (CLL). At diagnosis, no more than 5% of patients carry the 17p deletion, most cases harbour mutations within the other TP53 allele. The incidence of a TP53 mutation as the only alteration is approximately 5%, but this depends on the sensitivity of the technique. Recently, having a complex karyotype has been considered a strong adverse prognostic factor. However, there are no longitudinal studies simultaneously examining the presence of the 17p deletion, TP53 mutations and karyotype abnormalities. We conducted a retrospective longitudinal study of 31 relapsed/refractory CLL patients. Two to six blood samples per patient were analyzed, with a median follow-up of 8 years. In this report, we assessed the sequence of events of TP53 clonal evolution and correlated the presence of TP53 abnormalities to genetic instability during progression and treatment. Next-generation sequencing allowed the early detection of TP53 mutated clones and was able to be performed on a routine basis, demonstrating an excellent correlation between the Illumina and Ion Torrent technologies. We concluded that TP53 mutations are early events and precede clonal evolution to complex karyotypes. We strongly recommend the early and iterated detection of TP53 mutations in progressive cases. PMID:27270786

  1. Integration of sensory information precedes the sensation of vection: a combined behavioral and event-related brain potential (ERP) study.

    PubMed

    Keshavarz, Behrang; Berti, Stefan

    2014-02-01

    Illusory self-motion (known as vection) describes the sensation of ego-motion in the absence of physical movement. Vection typically occurs in stationary observers being exposed to visual information that suggest self-motion (e.g. simulators, virtual reality). In the present study, we tested whether sensory integration of visual information triggers vection: participants (N=13) perceived patterns of moving altered black-and-white vertical stripes on a screen that was divided into a central and a surrounding peripheral visual field. In both fields the pattern was either moving or stationary, resulting in four combinations of central and peripheral motions: (1) central and peripheral stripes moved into the same direction, (2) central and peripheral stripes moved in opposite directions, or (3) either the central or (4) the peripheral stripes were stable while the other stripes were in motion. This stimulation induced vection: Results showed significantly higher vection ratings when the stationary center of the pattern was surrounded by a moving periphery. Event-related potentials mirrored this finding: The occipital N2 was largest with stationary central and moving peripheral stripes. Our findings suggest that sensory integration of peripheral and central visual information triggers the perception of vection. Furthermore, we found evidence that neural processes precede the subjective perception of vection strength prior to the actual onset of vection. We will discuss our findings with respect to the role of stimulus eccentricity, stimulus' depth, and neural correlates involved during the genesis of vection. PMID:24211538

  2. Gait changes precede overt arthritis and strongly correlate with symptoms and histopathological events in pristane-induced arthritis

    PubMed Central

    2010-01-01

    Introduction Pristane-induced arthritis (PIA) in the rat has been described as an animal model of inflammatory arthritis which exhibits features similar to rheumatoid arthritis in humans, such as a chronic, destructive, and symmetrical involvement of peripheral joints. However, so far little is known about the earliest inflammatory events and their influence on locomotor behaviour during the course of PIA. To investigate this issue a detailed analysis of the pathologic changes occurring during the prodromal and early stages of PIA was performed. Methods Arthritis was induced in DA.rats by injection of 150 μl 2,6,10,4-tetramethyl-pentadecane (pristane) at the base of the tail and changes in locomotor behaviour of the affected paws were monitored using the CatWalk quantitative gait analysis system. The pathologic events occurring in the joints of pristane-injected animals were studied before onset, at onset, and during acute phase of arthritis by histological methods. Results Gait analysis revealed that changes in locomotion such as reduced paw print areas and stance phase time are already apparent before the onset of clinically discernible arthritis symptoms (erythema, paw swelling) and correlate with PIA scores. In agreement with these findings, inflammatory tenosynovitis could be observed by histology already before the onset of erythema and swelling of the respective paws. In the most heavily affected rats also irregularities in step sequence patterns occurred A kinetic analysis of clinical and histological findings demonstrated that gait changes precede the pathological changes occurring during the acute phase of pristane-induced arthritis. Conclusions Gait analysis allows for pinpointing the initial inflammatory changes in experimental arthritis models such as pristane-induced arthritis. Analysis of early clinically relevant symptoms in arthritis models may facilitate the search for novel therapeutics to interfere with pain, inflammation and joint destruction

  3. Localised calcium release events in cells from the muscle of guinea-pig gastric fundus

    PubMed Central

    Parsons, S P; Bolton, T B

    2004-01-01

    After enzymatic dispersion of the muscle of the guinea-pig gastric fundus, single elongated cells were observed which differed from archetypal smooth muscle cells due to their knurled, tuberose or otherwise irregular surface morphology. These, but not archetypal smooth muscle cells, consistently displayed spontaneous localized (i.e. non-propagating) intracellular calcium ([Ca2+]i) release events. Such calcium events were novel in their magnitude and kinetic profiles. They included short transient events, plateau events and events which coalesced spatially or temporally (compound events). Quantitative analysis of the events with an automatic detection programme showed that their spatio-temporal characteristics (full width and full duration at half-maximum amplitude) were approximately exponentially distributed. Their amplitude distribution suggested the presence of two release modes. Carbachol application caused an initial cell-wide calcium transient followed by an increase in localized calcium release events. Pharmacological analysis suggested that localized calcium release was largely dependent on external calcium entry acting on both inositol trisphosphate receptors (IP3Rs) and ryanodine receptors (RyRs) to release stored calcium. Nominally calcium-free external solution immediately and reversibly abolished all localized calcium release without blocking the initial transient calcium release response to carbachol. This was inhibited by 2-APB (100 μm), ryanodine (10 or 50 μm) or U-73122 (1 μm). 2-APB (100 μm), xestospongin C (XeC, 10 μm) or U-73122 (1 μm) blocked both spontaneous localized calcium release and localized release stimulated by 10 μm carbachol. Ryanodine (50 μm) also inhibited spontaneous release, but enhanced localized release in response to carbachol. This study represents the first characterization of localized calcium release events in cells from the gastric fundus. PMID:14608011

  4. Increased Mitochondrial Calcium Sensitivity and Abnormal Expression of Innate Immunity Genes Precede Dopaminergic Defects in Pink1-Deficient Mice

    PubMed Central

    Akundi, Ravi S.; Huang, Zhenyu; Eason, Joshua; Pandya, Jignesh D.; Zhi, Lianteng; Cass, Wayne A.; Sullivan, Patrick G.; Büeler, Hansruedi

    2011-01-01

    Background PTEN-induced kinase 1 (PINK1) is linked to recessive Parkinsonism (EOPD). Pink1 deletion results in impaired dopamine (DA) release and decreased mitochondrial respiration in the striatum of mice. To reveal additional mechanisms of Pink1-related dopaminergic dysfunction, we studied Ca2+ vulnerability of purified brain mitochondria, DA levels and metabolism and whether signaling pathways implicated in Parkinson's disease (PD) display altered activity in the nigrostriatal system of Pink1−/− mice. Methods and Findings Purified brain mitochondria of Pink1−/− mice showed impaired Ca2+ storage capacity, resulting in increased Ca2+ induced mitochondrial permeability transition (mPT) that was rescued by cyclosporine A. A subpopulation of neurons in the substantia nigra of Pink1−/− mice accumulated phospho-c-Jun, showing that Jun N-terminal kinase (JNK) activity is increased. Pink1−/− mice 6 months and older displayed reduced DA levels associated with increased DA turnover. Moreover, Pink1−/− mice had increased levels of IL-1β, IL-12 and IL-10 in the striatum after peripheral challenge with lipopolysaccharide (LPS), and Pink1−/− embryonic fibroblasts showed decreased basal and inflammatory cytokine-induced nuclear factor kappa-β (NF-κB) activity. Quantitative transcriptional profiling in the striatum revealed that Pink1−/− mice differentially express genes that (i) are upregulated in animals with experimentally induced dopaminergic lesions, (ii) regulate innate immune responses and/or apoptosis and (iii) promote axonal regeneration and sprouting. Conclusions Increased mitochondrial Ca2+ sensitivity and JNK activity are early defects in Pink1−/− mice that precede reduced DA levels and abnormal DA homeostasis and may contribute to neuronal dysfunction in familial PD. Differential gene expression in the nigrostriatal system of Pink1−/− mice supports early dopaminergic dysfunction and shows that Pink1 deletion causes aberrant

  5. Does calcium intake affect cardiovascular risk factors and/or events?

    PubMed Central

    Torres, Márcia Regina Simas Gonçalves; Sanjuliani, Antonio Felipe

    2012-01-01

    Dietary intervention is an important approach in the prevention of cardiovascular disease. Over the last decade, some studies have suggested that a calcium-rich diet could help to control body weight, with anti-obesity effects. The potential mechanism underlying the impact of calcium on body fat has been investigated, but it is not fully understood. Recent evidence has also suggested that a calcium-rich diet could have beneficial effects on other cardiovascular risk factors, such as insulin resistance, dyslipidemia, hypertension and inflammatory states. In a series of studies, it was observed that a high intake of milk and/or dairy products (the main sources of dietary calcium) is associated with a reduction in the relative risk of cardiovascular disease. However, a few studies suggest that supplemental calcium (mainly calcium carbonate or citrate) may be associated with an increased risk of cardiovascular events. This review will discuss the available evidence regarding the relationship between calcium intake (dietary and supplemental) and different cardiovascular risk factors and/or events. PMID:22892932

  6. Recent Life Events Preceding Suicide Attempts in a Personality Disorder Sample: Findings from the Collaborative Longitudinal Personality Disorders Study

    ERIC Educational Resources Information Center

    Yen, Shirley; Pagano, Maria E.; Shea, Tracie M.; Grilo, Carlos M.; Gunderson, John G.; Skodol, Andrew E.; McGlashan, Thomas H.; Sanislow, Charles A.; Bender, Donna S.

    2005-01-01

    Few studies have examined the relationship between life events, suicide attempts, and personality disorders (PDs), in spite of the strong associations between PDs and suicidal behavior, and the poor coping strategies often exhibited by these individuals. The authors examined whether participants with PDs who attempted suicide during the first 3…

  7. Calcium

    MedlinePlus

    ... of calcium dietary supplements are carbonate and citrate. Calcium carbonate is inexpensive, but is absorbed best when taken ... antacid products, such as Tums® and Rolaids®, contain calcium carbonate. Each pill or chew provides 200–400 mg ...

  8. Protein kinases as mediators of fluid shear stress stimulated signal transduction in endothelial cells: a hypothesis for calcium-dependent and calcium-independent events activated by flow.

    PubMed

    Berk, B C; Corson, M A; Peterson, T E; Tseng, H

    1995-12-01

    Fluid shear stress regulates endothelial cell function, but the signal transduction mechanisms involved in mechanotransduction remain unclear. Recent findings demonstrate that several intracellular kinases are activated by mechanical forces. In particular, members of the mitogen-activated protein (MAP) kinase family are stimulated by hyperosmolarity, stretch, and stress such as heat shock. We propose a model for mechanotransduction in endothelial cells involving calcium-dependent and calcium-independent protein kinase pathways. The calcium-dependent pathway involves activation of phospholipase C, hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP2), increases in intracellular calcium and stimulation of kinases such as calcium-calmodulin and C kinases (PKC). The calcium-independent pathway involves activation of a small GTP-binding protein and stimulation of calcium-independent PKC and MAP kinases. The calcium-dependent pathway mediates the rapid, transient response to fluid shear stress including activation of nitric oxide synthase (NOS) and ion transport. In contrast, the calcium-independent pathway mediates a slower response including the sustained activation of NOS and changes in cell morphology and gene expression. We propose that focal adhesion complexes link the calcium-dependent and calcium-independent pathways by regulating activity of phosphatidylinositol 4-phosphate (PIP) 5-kinase (which regulates PIP2 levels) and p125 focal adhesion kinase (FAK, which phosphorylates paxillin and interacts with cytoskeletal proteins). This model predicts that dynamic interactions between integrin molecules present in focal adhesion complexes and membrane events involved in mechanotransduction will be integrated by calcium-dependent and calcium-independent kinases to generate intracellular signals involved in the endothelial cell response to flow. PMID:8666584

  9. Preceding seismic activity and slow slip events in the source area of the 2011 Mw 9.0 Tohoku-Oki earthquake: a review

    NASA Astrophysics Data System (ADS)

    Hasegawa, Akira; Yoshida, Keisuke

    2015-12-01

    The 2011 Tohoku-Oki earthquake ruptured a large area of the megathrust east of NE Japan. The earthquake's magnitude was 9.0, substantially larger than predicted. It is important to know what occurred in the source area prior to this great megathrust earthquake to improve understanding of the nucleation processes of large earthquakes and risk assessments in subduction zones. Seafloor observation data revealed the existence of two extremely large slip patches: one just updip of the mainshock hypocenter and the other 80-100 km to the north near the trench axis. For 70-90 years before 2003, M > 6 events and slips of M > c. 7 events on the megathrust occurred in the areas surrounding these two large slip patches. Seismic activity had increased since at least 2003 in the downdip portion of the source area of the Tohoku-Oki earthquake. In addition, long-term accelerated slow slip occurred in this downdip portion of the source area in the decades before the Tohoku-Oki earthquake. About 1 month before the earthquake, a slow slip event (SSE) took place at relatively shallow depths between the two large slip patches, accompanied by foreshock activity. Both the slow slip and foreshocks propagated from north to south toward the southern large slip patch. Two days before the earthquake, an M 7.3 foreshock and an associated postseismic slip began at relatively deep depths in the megathrust between the two large slip patches. In addition, a slow slip type event seems to have occurred approximately half a day after the M 7.3 foreshock near the mainshock hypocenter. This slow slip event and the foreshock activity again propagated from north to south toward the mainshock hypocenter. These long- and short-term preceding seismic and aseismic slip gradually reduced the interplate coupling, increased shear stresses at the two large slip patches (i.e., two strong asperity patches), and finally led to the rupture of the great Tohoku-Oki earthquake.

  10. Calcium

    MedlinePlus

    ... body stores more than 99 percent of its calcium in the bones and teeth to help make and keep them ... in the foods you eat. Foods rich in calcium include Dairy products such as milk, cheese, and yogurt Leafy, green vegetables Fish with soft bones that you eat, such as canned sardines and ...

  11. Calcium

    MedlinePlus

    ... milligrams) of calcium each day. Get it from: Dairy products. Low-fat milk, yogurt, cheese, and cottage ... lactase that helps digest the sugar (lactose) in dairy products, and may have gas, bloating, cramps, or ...

  12. Coronary artery calcium and exercise electrocardiogram as predictors of coronary events in asymptomatic adults.

    PubMed

    Grossman, Chagai; Ehrlich, Shay; Shemesh, Joseph; Koren-Morag, Nira; Grossman, Ehud

    2015-03-15

    Early identification of patients at risk for coronary heart disease is crucial to formulate effective preventive strategies. The elevated risk of coronary artery calcium (CAC) for coronary heart disease is well established. Our aim was to estimate the relative risk of abnormal exercise electrocardiography (Ex ECG) in the presence of CAC. During the year 2001, 566 asymptomatic subjects performed a treadmill exercise test and consented to perform an unenhanced computed tomography to assess CAC. Patients were followed until December 2012. The relative risk for coronary events (acute myocardial infarction, hospitalization for unstable angina or coronary catheterization that resulted in angioplasty or coronary artery bypass surgery), of abnormal Ex ECG and presence of CAC were analyzed. An abnormal Ex ECG was found in 71 subjects (12.5%), and CAC was found in 286 subjects (50.5%). During a mean follow-up of 6.5 ± 3.3 years, 35 subjects experienced a first coronary event. In those without CAC, the rate of coronary events was low (4 of 280; 1.4%) regardless of the Ex ECG results. Subjects with both CAC and abnormal Ex ECG had the highest rate of coronary events (13 of 39; 33%). The adjusted hazard ratio for coronary events, in subjects with CAC, was 5.16 (95% confidence interval 2.52 to 10.60) in those with abnormal Ex ECG compared with those with normal Ex ECG. In conclusion, in subjects with CAC, further risk stratification can be achieved by an Ex ECG, whereas in those without CAC, an Ex ECG has less additional value in predicting coronary events. PMID:25616536

  13. Stochastic spontaneous calcium release events trigger premature ventricular complexes by overcoming electrotonic load

    PubMed Central

    Campos, Fernando O.; Shiferaw, Yohannes; Prassl, Anton J.; Boyle, Patrick M.; Vigmond, Edward J.; Plank, Gernot

    2015-01-01

    Aims Premature ventricular complexes (PVCs) due to spontaneous calcium (Ca) release (SCR) events at the cell level can precipitate ventricular arrhythmias. However, the mechanistic link between SCRs and PVC formation remains incompletely understood. The aim of this study was to investigate the conditions under which delayed afterdepolarizations resulting from stochastic subcellular SCR events can overcome electrotonic source–sink mismatch, leading to PVC initiation. Methods and results A stochastic subcellular-scale mathematical model of SCR was incorporated in a realistic model of the rabbit ventricles and Purkinje system (PS). Elevated levels of diastolic sarcoplasmic reticulum Ca2+ (CaSR) were imposed until triggered activity was observed, allowing us to compile statistics on probability, timing, and location of PVCs. At CaSR≥ 1500 µmol/L PVCs originated in the PS. When SCR was incapacitated in the PS, PVCs also emerged in the ventricles, but at a higher CaSR (≥1550 µmol/L) and with longer waiting times. For each model configuration tested, the probability of PVC occurrence increased from 0 to 100% within a well-defined critical CaSR range; this transition was much more abrupt in organ-scale models (∼50 µmol/L CaSR range) than in the tissue strand (∼100 µmol/L) or single-cell (∼450 µmol/L) models. Among PVCs originating in the PS, ∼68% were located near Purkinje-ventricular junctions (<1 mm). Conclusion SCR events overcome source–sink mismatch to trigger PVCs at a critical CaSR threshold. Above this threshold, PVCs emerge due to increased probability and reduced variability in timing of SCR events, leading to significant diastolic depolarization. Sites of lower electronic load, such as the PS, are preferential locations for triggering. PMID:25969391

  14. Risks of Adverse Events Following Coprescription of Statins and Calcium Channel Blockers

    PubMed Central

    Wang, Yi-Chun; Hsieh, Tsung-Cheng; Chou, Chu-Lin; Wu, Jung-Lun; Fang, Te-Chao

    2016-01-01

    Abstract Some statins (simvastatin, lovastatin, and atorvastatin) are metabolized by cytochrome P450s 3A4 (CYP3A4). Inhibitors of CYP3A4 including some calcium channel blockers (CCBs) might increase statin blood concentration, owing to drug–drug interactions. Risk of adverse events such as acute kidney injury might occur following the coprescription of CYP3A4-metabolized statins and CCBs that inhibit CYP3A4. This was a population-based cohort study. The study analyzed data of patients treated between 1997 and 2011, retrieved from Taiwan's National Health Insurance database. We enrolled 32,801 patients who received coprescription of statins and CCBs that inhibit CYP3A4 (amlodipine, diltiazem, felodipine nicardipine, nifedipine, and verapamil). These patients were divided into 2 groups, according to whether they had received CYP3A4-metabolized statins (lovastatin, simvastatin, and atorvastatin) or non-CYP3A4-metabolized statins (fluvastatin, rosuvastatin, and pitavastatin). These 2 groups were 1:1 matched by age, gender, and Carlson comorbidity index. All outcomes were assessed within 90 days following drug coprescription. In this study, 5857 patients received coprescription of CYP3A4-metabolized statins and CCBs that inhibit CYP3A4. There were no differences in comorbidity or use of antihypertensive drugs between patients who received CYP3A4-metabolized statins and those who received non-CYP3A4-metabolized statins. Patients who received CYP3A4-metabolized statins had significantly higher risk of acute kidney injury (adjusted odds ratio [OR] = 2.12; 95% CI = 1.35–3.35), hyperkalemia (adjusted OR = 2.94; 95% CI = 1.36–6.35), acute myocardial infarction (adjusted OR = 1.55; 95% CI = 1.16–2.07), and acute ischemic stroke (adjusted OR = 1.35; 95% CI = 1.08–1.68) than those who received non-CYP3A4-metabolized statins. This nationwide cohort study demonstrated the increased risk of adverse events following the coprescription of CYP

  15. Effect of calcium, bicarbonate, and albumin on capacitation-related events in equine sperm.

    PubMed

    Macías-García, B; González-Fernández, L; Loux, S C; Rocha, A M; Guimarães, T; Peña, F J; Varner, D D; Hinrichs, K

    2015-01-01

    Repeatable methods for IVF have not been established in the horse, reflecting the failure of standard capacitating media to induce changes required for fertilization capacity in equine sperm. One important step in capacitation is membrane cholesterol efflux, which in other species is triggered by cholesterol oxidation and is typically enhanced using albumin as a sterol acceptor. We incubated equine sperm in the presence of calcium, BSA, and bicarbonate, alone or in combination. Bicarbonate induced an increase in reactive oxygen species (ROS) that was abolished by the addition of calcium or BSA. Bicarbonate induced protein tyrosine phosphorylation (PY), even in the presence of calcium or BSA. Incubation at high pH enhanced PY but did not increase ROS production. Notably, no combination of these factors was associated with significant cholesterol efflux, as assessed by fluorescent quantitative cholesterol assay and confirmed by filipin staining. By contrast, sperm treated with methyl-β-cyclodextrin showed a significant reduction in cholesterol levels, but no significant increase in PY or ROS. Presence of BSA increased sperm binding to bovine zonae pellucidae in all three stallions. These results show that presence of serum albumin is not associated with a reduction in membrane cholesterol levels in equine sperm, highlighting the failure of equine sperm to exhibit core capacitation-related changes in a standard capacitating medium. These data indicate an atypical relationship among cholesterol efflux, ROS production, and PY in equine sperm. Our findings may help to elucidate factors affecting failure of equine IVF under standard conditions. PMID:25349439

  16. Curcumin induces crosstalk between autophagy and apoptosis mediated by calcium release from the endoplasmic reticulum, lysosomal destabilization and mitochondrial events

    PubMed Central

    Moustapha, A; Pérétout, PA; Rainey, NE; Sureau, F; Geze, M; Petit, J-M; Dewailly, E; Slomianny, C; Petit, PX

    2015-01-01

    Curcumin, a major active component of turmeric (Curcuma longa, L.), has anticancer effects. In vitro studies suggest that curcumin inhibits cancer cell growth by activating apoptosis, but the mechanism underlying these effects is still unclear. Here, we investigated the mechanisms leading to apoptosis in curcumin-treated cells. Curcumin induced endoplasmic reticulum stress causing calcium release, with a destabilization of the mitochondrial compartment resulting in apoptosis. These events were also associated with lysosomal membrane permeabilization and of caspase-8 activation, mediated by cathepsins and calpains, leading to Bid cleavage. Truncated tBid disrupts mitochondrial homeostasis and enhance apoptosis. We followed the induction of autophagy, marked by the formation of autophagosomes, by staining with acridine orange in cells exposed curcumin. At this concentration, only the early events of apoptosis (initial mitochondrial destabilization with any other manifestations) were detectable. Western blotting demonstrated the conversion of LC3-I to LC3-II (light chain 3), a marker of active autophagosome formation. We also found that the production of reactive oxygen species and formation of autophagosomes following curcumin treatment was almost completely blocked by N-acetylcystein, the mitochondrial specific antioxidants MitoQ10 and SKQ1, the calcium chelators, EGTA-AM or BAPTA-AM, and the mitochondrial calcium uniporter inhibitor, ruthenium red. Curcumin-induced autophagy failed to rescue all cells and most cells underwent type II cell death following the initial autophagic processes. All together, these data imply a fail-secure mechanism regulated by autophagy in the action of curcumin, suggesting a therapeutic potential for curcumin. Offering a novel and effective strategy for the treatment of malignant cells. PMID:27551451

  17. Patterns of seismic activity preceding large earthquakes

    NASA Technical Reports Server (NTRS)

    Shaw, Bruce E.; Carlson, J. M.; Langer, J. S.

    1992-01-01

    A mechanical model of seismic faults is employed to investigate the seismic activities that occur prior to major events. The block-and-spring model dynamically generates a statistical distribution of smaller slipping events that precede large events, and the results satisfy the Gutenberg-Richter law. The scaling behavior during a loading cycle suggests small but systematic variations in space and time with maximum activity acceleration near the future epicenter. Activity patterns inferred from data on seismicity in California demonstrate a regional aspect; increased activity in certain areas are found to precede major earthquake events. One example is given regarding the Loma Prieta earthquake of 1989 which is located near a fault section associated with increased activity levels.

  18. Calcium isotopes in caves as a proxy for aridity: Modern calibration and application to the 8.2 kyr event

    NASA Astrophysics Data System (ADS)

    Owen, R. A.; Day, C. C.; Hu, C.-Y.; Liu, Y.-H.; Pointing, M. D.; Blättler, C. L.; Henderson, G. M.

    2016-06-01

    We present the first study of Ca isotope cycling in a natural cave system, with measurements of bedrock, dripwater and recently formed carbonate, coupled to a first stalagmite time-series spanning the 8.2 kyr event. Dripwaters at Heshang Cave (Central China; 30°27‧N, 110°25‧E) are isotopically heavy relative to the dolomite bedrock, the result of prior calcite precipitation (PCP) occurring earlier in the drip flow path. A simple Rayleigh fractionation model quantifies the extent of PCP in the modern environment at 36% Ca removal. The observed in situ calcium isotope fractionation factor between dripwater and carbonate is Δ 44 / 42 Ca = - 0.63 ± 0.03 ‰ and does not vary during the annual cycle. Measurements of speleothem carbonate spanning the 8.2 kyr event show the response of Ca isotopes to changing climate. δ44/42Ca increases by 0.35‰ at the onset of the event, coeval with changes in δ18O and Mg/Ca, and remains high for 80 yr. This change is explained by decreased rainfall leading to increased PCP; an interpretation supported by established PCP proxies (Mg/Ca, Sr/Ca and Ba/Ca). Ca isotopes indicate that PCP increased to 60% Ca removal during the event, which, from application of a simple box model, suggests mean annual rainfall decreased by approximately a third in Central China during the 8.2 kyr event. The response of Ca isotopes across this event demonstrates their potential for the assessment of past conditions, including past dripwater flow rates and rainfall.

  19. Progression of Coronary Calcium and Incident Coronary Heart Disease Events: The Multi-Ethnic Study of Atherosclerosis

    PubMed Central

    Budoff, Matthew J.; Young, Rebekah; Lopez, Victor A.; Kronmal, Richard A.; Nasir, Khurram; Blumenthal, Roger S.; Detrano, Robert C.; Bild, Diane E.; Guerci, Alan D.; Liu, Kiang; Shea, Steven; Szklo, Moyses; Post, Wendy; Lima, Joao; Bertoni, Alain; Wong, Nathan D.

    2014-01-01

    Background Coronary artery calcium (CAC) predicts coronary heart disease (CHD) events and serial measurement of CAC has been proposed to evaluate atherosclerosis progression. We examined whether progression of CAC is a predictor of future CHD events. Methods and Results We studied 6,778 persons (52.8% female) aged 45–84 years from the Multi-Ethnic Study of Atherosclerosis. 5,682 persons had baseline and follow-up CAC scans approximately 2.5 ± 0.8 years apart; multiple imputation was used to account for the remainder (n=1,096) missing follow-up scans. Median follow-up duration from the baseline was 7.6 (max=9.0) years. CAC change was assessed by absolute change between baseline and follow-up CAC. Cox proportional hazards regression providing hazard ratios (HR) examined the relation of change in CAC with CHD events, adjusting for age, gender, ethnicity, baseline calcium score, and other risk factors. 343 total and 206 hard CHD events occurred. The annual change in CAC averaged 24.9 ± 65.3 units. Among persons without CAC at baseline (n=3,396), a 5 unit annual change in CAC was associated with an adjusted HR of 1.4 (1.0–1.9) for total and 1.5 (1.1–2.1) for hard CHD. Among those with CAC>0 at baseline HR’s (per 100 unit annual change) were 1.2 (1.1–1.4) and 1.3 (1.1–1.5), respectively. Among participants with baseline CAC, those with annual progression of ≥300 units had adjusted HR’s of 3.8 (1.5–9.6) for total and 6.3 (1.9–21.5) for hard CHD compared to those without progression. Conclusions Progression of CAC is associated with an increased risk for future hard and total CHD events. PMID:23500326

  20. Calcium isotope evidence for dramatic increase of continental weathering during the Toarcian oceanic anoxic event (Early Jurassic)

    NASA Astrophysics Data System (ADS)

    Brazier, Jean-Michel; Suan, Guillaume; Tacail, Théo; Simon, Laurent; Martin, Jeremy E.; Mattioli, Emanuela; Balter, Vincent

    2015-02-01

    The early Toarcian was punctuated by pulses of massive carbon injection that are thought to have triggered, through increased greenhouse conditions, elevated continental discharge and nutrient input, marine anoxia, seawater acidification and species extinctions. Nevertheless, the mode and tempo of changes in continental weathering across this interval remains highly debated, leading to considerable uncertainty about the main causes of these perturbations. In this study we present calcium isotope measurements (δ44/40Ca) of well-preserved brachiopods and bulk rock samples from the hemipelagic strata of Pliensbachian-Toarcian age of Peniche in Portugal in order to constrain changes in the calcium cycle and hence changes in continental weathering during the early Toarcian. The data reveal a similar trend as carbon isotope data from the same section and show negative excursions of about 0.5‰ at the Pliensbachian-Toarcian transition (Pl-To) and at the base of the Toarcian Oceanic Anoxic Event (T-OAE) interval. The comparison of δ44/40Ca ratios recorded in brachiopods and bulk rock corrected for variable dolomite contribution indicates that these excursions reflect changes in the global isotopic composition of seawater rather than changes in the dominant mineralogy of calcifying organisms or in hydrological budget of the considered basin. Box modeling results suggest that the Pl-To and T-OAE δ44/40Ca excursions can be explained by a transient 90% decrease of carbonate accumulation due to seawater acidification followed by a 500% increase in continental weathering rates. The sharp increases in continental weathering inferred from the δ44/40Ca ratios seem overall consistent with lower Toarcian sedimentological and biotic records that document rapid crises in carbonate production followed by episodes of increased calcium carbonate burial. Nevertheless, the maximum of carbonate burial recorded by most NW European basinal successions occurs several hundreds of kyrs after

  1. Risks of Adverse Events Following Coprescription of Statins and Calcium Channel Blockers: A Nationwide Population-Based Study.

    PubMed

    Wang, Yi-Chun; Hsieh, Tsung-Cheng; Chou, Chu-Lin; Wu, Jung-Lun; Fang, Te-Chao

    2016-01-01

    Some statins (simvastatin, lovastatin, and atorvastatin) are metabolized by cytochrome P450s 3A4 (CYP3A4). Inhibitors of CYP3A4 including some calcium channel blockers (CCBs) might increase statin blood concentration, owing to drug-drug interactions. Risk of adverse events such as acute kidney injury might occur following the coprescription of CYP3A4-metabolized statins and CCBs that inhibit CYP3A4.This was a population-based cohort study. The study analyzed data of patients treated between 1997 and 2011, retrieved from Taiwan's National Health Insurance database. We enrolled 32,801 patients who received coprescription of statins and CCBs that inhibit CYP3A4 (amlodipine, diltiazem, felodipine nicardipine, nifedipine, and verapamil). These patients were divided into 2 groups, according to whether they had received CYP3A4-metabolized statins (lovastatin, simvastatin, and atorvastatin) or non-CYP3A4-metabolized statins (fluvastatin, rosuvastatin, and pitavastatin). These 2 groups were 1:1 matched by age, gender, and Carlson comorbidity index. All outcomes were assessed within 90 days following drug coprescription.In this study, 5857 patients received coprescription of CYP3A4-metabolized statins and CCBs that inhibit CYP3A4. There were no differences in comorbidity or use of antihypertensive drugs between patients who received CYP3A4-metabolized statins and those who received non-CYP3A4-metabolized statins. Patients who received CYP3A4-metabolized statins had significantly higher risk of acute kidney injury (adjusted odds ratio [OR] = 2.12; 95% CI = 1.35-3.35), hyperkalemia (adjusted OR = 2.94; 95% CI = 1.36-6.35), acute myocardial infarction (adjusted OR = 1.55; 95% CI = 1.16-2.07), and acute ischemic stroke (adjusted OR = 1.35; 95% CI = 1.08-1.68) than those who received non-CYP3A4-metabolized statins.This nationwide cohort study demonstrated the increased risk of adverse events following the coprescription of CYP3A4-metabolized

  2. Addenda to the Preceding Paper

    NASA Astrophysics Data System (ADS)

    Bhatnagar, Rajat; Finn, Robert

    2016-05-01

    This work contains largely afterthoughts, relating to the paper immediately preceding it. We correlate and interpret our contributions in that paper, relative to those of an earlier publication by Aspley, He and McCuan. We propose specific laboratory experiments, suggested by formal predictions of those two papers.

  3. Calcium antagonists.

    PubMed

    Grossman, Ehud; Messerli, Franz H

    2004-01-01

    Calcium antagonists were introduced for the treatment of hypertension in the 1980s. Their use was subsequently expanded to additional disorders, such as angina pectoris, paroxysmal supraventricular tachycardias, hypertrophic cardiomyopathy, Raynaud phenomenon, pulmonary hypertension, diffuse esophageal spasms, and migraine. Calcium antagonists as a group are heterogeneous and include 3 main classes--phenylalkylamines, benzothiazepines, and dihydropyridines--that differ in their molecular structure, sites and modes of action, and effects on various other cardiovascular functions. Calcium antagonists lower blood pressure mainly through vasodilation and reduction of peripheral resistance. They maintain blood flow to vital organs, and are safe in patients with renal impairment. Unlike diuretics and beta-blockers, calcium antagonists do not impair glucose metabolism or lipid profile and may even attenuate the development of arteriosclerotic lesions. In long-term follow-up, patients treated with calcium antagonists had development of less overt diabetes mellitus than those who were treated with diuretics and beta-blockers. Moreover, calcium antagonists are able to reduce left ventricular mass and are effective in improving anginal pain. Recent prospective randomized studies attested to the beneficial effects of calcium antagonists in hypertensive patients. In comparison with placebo, calcium antagonist-based therapy reduced major cardiovascular events and cardiovascular death significantly in elderly hypertensive patients and in diabetic patients. In several comparative studies in hypertensive patients, treatment with calcium antagonists was equally effective as treatment with diuretics, beta-blockers, or angiotensin-converting enzyme inhibitors. From these studies, it seems that a calcium antagonist-based regimen is superior to other regimens in preventing stroke, equivalent in preventing ischemic heart disease, and inferior in preventing congestive heart failure

  4. 47 CFR 213.5 - Precedence designators.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Precedence designators. 213.5 Section 213.5 Telecommunication OFFICE OF SCIENCE AND TECHNOLOGY POLICY AND NATIONAL SECURITY COUNCIL GOVERNMENT AND PUBLIC CORRESPONDENCE TELECOMMUNICATIONS PRECEDENCE SYSTEM § 213.5 Precedence designators. (a) The following precedence designators are available...

  5. Mouse neuroblastoma cell based model and the effect of epileptic events on calcium oscillations and neural spikes

    NASA Astrophysics Data System (ADS)

    Kim, Suhwan; Baek, Juyeong; Jung, Unsang; Lee, Sangwon; Jung, Woonggyu; Kim, Jeehyun; Kang, Shinwon

    2013-05-01

    Recently, Mouse neuroblastoma cells are considered as an attractive model for the study of human neurological and prion diseases, and intensively used as a model system in different areas. Among those areas, differentiation of neuro2a (N2A) cells, receptor mediated ion current, and glutamate induced physiological response are actively investigated. The reason for the interest to mouse neuroblastoma N2A cells is that they have a fast growing rate than other cells in neural origin with a few another advantages. This study evaluated the calcium oscillations and neural spikes recording of mouse neuroblastoma N2A cells in an epileptic condition. Based on our observation of neural spikes in mouse N2A cell with our proposed imaging modality, we report that mouse neuroblastoma N2A cells can be an important model related to epileptic activity studies. It is concluded that the mouse neuroblastoma N2A cells produce the epileptic spikes in vitro in the same way as produced by the neurons or the astrocytes. This evidence advocates the increased and strong level of neurotransmitters release by enhancement in free calcium using the 4-aminopyridine which causes the mouse neuroblastoma N2A cells to produce the epileptic spikes and calcium oscillation.

  6. Mouse neuroblastoma cell-based model and the effect of epileptic events on calcium oscillations and neural spikes

    NASA Astrophysics Data System (ADS)

    Kim, Suhwan; Jung, Unsang; Baek, Juyoung; Lee, Sangwon; Jung, Woonggyu; Kim, Jeehyun; Kang, Shinwon

    2013-01-01

    Recently, mouse neuroblastoma cells have been considered as an attractive model for the study of human neurological and prion diseases, and they have been intensively used as a model system in different areas. For example, the differentiation of neuro2a (N2A) cells, receptor-mediated ion current, and glutamate-induced physiological responses have been actively investigated with these cells. These mouse neuroblastoma N2A cells are of interest because they grow faster than other cells of neural origin and have a number of other advantages. The calcium oscillations and neural spikes of mouse neuroblastoma N2A cells in epileptic conditions are evaluated. Based on our observations of neural spikes in these cells with our proposed imaging modality, we reported that they can be an important model in epileptic activity studies. We concluded that mouse neuroblastoma N2A cells produce epileptic spikes in vitro in the same way as those produced by neurons or astrocytes. This evidence suggests that increased levels of neurotransmitter release due to the enhancement of free calcium from 4-aminopyridine causes the mouse neuroblastoma N2A cells to produce epileptic spikes and calcium oscillations.

  7. Mini-dystrophin Expression Down-regulates IP3-mediated Calcium Release Events in Resting Dystrophin-deficient Muscle Cells

    PubMed Central

    Balghi, Haouaria; Sebille, Stéphane; Mondin, Ludivine; Cantereau, Anne; Constantin, Bruno; Raymond, Guy; Cognard, Christian

    2006-01-01

    We present here evidence for the enhancement, at rest, of an inositol 1,4,5-trisphosphate (IP3)–mediated calcium signaling pathway in myotubes from dystrophin-deficient cell lines (SolC1(−)) as compared to a cell line from the same origin but transfected with mini-dystrophin (SolD(+)). With confocal microscopy, the number of sites discharging calcium (release site density [RSD]) was quantified and found more elevated in SolC1(−) than in SolD(+) myotubes. Variations of membrane potential had no significant effect on this difference, and higher resting [Ca2+]i in SolC1(−) (Marchand, E., B. Constantin, H. Balghi, M.C. Claudepierre, A. Cantereau, C. Magaud, A. Mouzou, G. Raymond, S. Braun, and C. Cognard. 2004. Exp. Cell Res. 297:363–379) cannot explain alone higher RSD. The exposure with SR Ca2+ channel inhibitors (ryanodine and 2-APB) and phospholipase C inhibitor (U73122) significantly reduced RSD in both cell types but with a stronger effect in dystrophin-deficient SolC1(−) myotubes. Immunocytochemistry allowed us to localize ryanodine receptors (RyRs) as well as IP3 receptors (IP3Rs), IP3R-1 and IP3R-2 isoforms, indicating the presence of both RyRs-dependent and IP3-dependent release systems in both cells. We previously reported evidence for the enhancement, through a Gi protein, of the IP3-mediated calcium signaling pathway in SolC1(−) as compared to SolD(+) myotubes during a high K+ stimulation (Balghi, H., S. Sebille, B. Constantin, S. Patri, V. Thoreau, L. Mondin, E. Mok, A. Kitzis, G. Raymond, and C. Cognard. 2006. J. Gen. Physiol. 127:171–182). Here we show that, at rest, these regulation mechanisms are also involved in the modulation of calcium release activities. The enhancement of resting release activity may participate in the calcium overload observed in dystrophin-deficient myotubes, and our findings support the hypothesis of the regulatory role of mini-dystrophin on intracellular signaling. PMID:16847098

  8. Calcium supplements

    MedlinePlus

    ... TYPES OF CALCIUM SUPPLEMENTS Forms of calcium include: Calcium carbonate: Over-the-counter (OTC) antacid products, such as Tums and Rolaids, contain calcium carbonate. These sources of calcium do not cost much. ...

  9. Counselor Interventions Preceding Client Laughter in Brief Therapy.

    ERIC Educational Resources Information Center

    Falk, Dana R.; Hill, Clara E.

    1992-01-01

    Examined whether 6 categories of counselor humor and 4 categories of risk interventions preceded client laughter in 236 events from 8 cases of brief psychotherapy. Found most client laughter was mild and moderate, with only eight instances of strong laughter. Humorous interventions led to more client laughter than did interventions that encouraged…

  10. 47 CFR 213.5 - Precedence designators.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Precedence designators. 213.5 Section 213.5 Telecommunication OFFICE OF SCIENCE AND TECHNOLOGY POLICY AND NATIONAL SECURITY COUNCIL GOVERNMENT AND PUBLIC CORRESPONDENCE TELECOMMUNICATIONS PRECEDENCE SYSTEM § 213.5 Precedence designators. (a) The following...

  11. Precedence relationship representations of mechanical assembly sequences

    NASA Technical Reports Server (NTRS)

    Homendemello, L. S.; Sanderson, A. C.

    1989-01-01

    Two types of precedence relationship representations for mechanical assembly sequences are presented: precedence relationships between the establishment of one connection between two parts and the establishment of another connection, and precedence relationships between the establishment of one connection and states of the assembly process. Precedence relationship representations have the advantage of being very compact. The problem with these representations was how to guarantee their correctness and completeness. Two theorems are presented each of which leads to the generation of one type of precedence relationship representation guaranteeing its correctness and completeness for a class of assemblies.

  12. Calcium - ionized

    MedlinePlus

    ... at both ionized calcium and calcium attached to proteins. You may need to have a separate ionized calcium test if you have factors that increase or decrease total calcium levels. These may include abnormal blood levels ...

  13. Association between adherence to calcium-channel blocker and statin medications and likelihood of cardiovascular events among US managed care enrollees

    PubMed Central

    2010-01-01

    Background Prior studies have found that patients taking single-pill amlodipine/atorvastatin (SPAA) have greater likelihood of adherence at 6 months than those taking 2-pill calcium-channel blocker and statin combinations (CCB/statin). This study examines whether this adherence benefit results in fewer cardiovascular (CV) events. Methods A retrospective cohort study was conducted using administrative claims data from the IMS LifeLink: US Health Plan Claims database, identifying adults already taking CCB or statin (but not both) who had an index event of either initiating treatment with SPAA or adding CCB to statin (or vice versa) between April 1, 2004 to August 31, 2005. Inclusion criteria included age 18+ years, continuously enrolled for minimum of 6 months prior and 18 months following treatment initiation, >1 diagnosis of hypertension, and no prescription claims for SPAA or added CCB or statin for 6 months prior. Exclusion criteria included >1 claim with missing or invalid days supplied, age 65+ years and not enrolled in Medicare Advantage, or history of prior CV events, cancer diagnosis, or chronic renal failure. The primary outcome measure was the rate of CV events (myocardial infarction, heart failure, angina, other ischemic heart disease, stroke, peripheral vascular disease, or revascularization procedure) from 6 to 18 months following index date, analyzed at three levels: 1) all adherent vs. non-adherent patients, 2) SPAA vs. dual-pill patients (regardless of adherence level), and 3) adherent SPAA, adherent dual-pill, and non-adherent SPAA patients vs. non-adherent dual-pill patients. Results Of 1,537 SPAA patients, 56.5% were adherent at 6 months, compared with 21.4% of the 17,910 CCB/statin patients (p < 0.001). Logistic regression found SPAA patients more likely to be adherent (OR = 4.7, p < 0.001) than CCB/statin patients. In Cox proportional hazards models, being adherent to either regimen was associated with significantly lower risk of CV event (HR

  14. The effects of a whole-watershed calcium addition on the chemistry of stream storm events at the Hubbard Brook Experimental Forest in NH, USA.

    PubMed

    Cho, Youngil; Driscoll, Charles T; Blum, Joel D

    2009-10-01

    Patterns of storm runoff chemistry from a wollastonite (calcium-silicate mineral, CaSiO(3)) treated watershed (W1) were compared with a reference watershed (W6) at the Hubbard Brook Experimental Forest (HBEF) in New Hampshire (NH), USA to investigate the role of Ca(2+) supply in the acid-base status of stream chemistry. In the summer of 2003, six storm events were studied in W1 and W6 to evaluate the effects of the wollastonite treatment on the episodic acidification of stream waters. Although mean values of Ca(2+) concentrations decreased slightly from 33.8 to 31.7 mumol/L with increasing stream discharge in W1 during the events, the mean value of acid neutralizing capacity (ANC) was positive (1.2 mueq/L) during storm events, compared to negative values (-0.2 mueq/L) in W6. This pattern is presumably due to enhanced Ca(2+) supply in W1 (20.7 to 29.0% of dissolved Ca(2+) derived from the added wollastonite) to stream water as a result of interflow along shallow flowpaths. In addition, the application of wollastonite increased pH and dissolved silica (H(4)SiO(4)) concentrations, and decreased the concentration of inorganic monomeric Al (Al(i)) in W1 in comparison with W6 during storm events. Despite an increase in SO(4)(2-) concentration, likely due to desorption of sulfate from soil after the treatment, the watershed showed an increase in ANC compared to the reference watershed, serving to mitigate episodic acidification. PMID:19640565

  15. Lesion-specific coronary artery calcium quantification for predicting cardiac event with multiple instance support vector machines.

    PubMed

    Liu, Qingshan; Qian, Zhen; Marvasty, Idean; Rinehart, Sarah; Voros, Szilard; Metaxas, Dimitris N

    2010-01-01

    Conventional whole-heart CAC quantification has been demonstrated to be insufficient in predicting coronary events, especially in accurately predicting near-term coronary events in high-risk adults. In this paper, we propose a lesion-specific CAC quantification framework to improve CAC's near-term predictive value in intermediate to high-risk populations with a novel multiple instance support vector machines (MISVM) approach. Our method works on data sets acquired with clinical imaging protocols on conventional CT scanners without modifying the CT hardware or updating the imaging protocol. The calcific lesions are quantified by geometric information, density, and some clinical measurements. A MISVM model is built to predict cardiac events, and moreover, to give a better insight of the characterization of vulnerable or culprit lesions in CAC. Experimental results on 31 patients showed significant improvement of the predictive value with the ROC analysis, the net reclassification improvement evaluation, and the leave-one-out validation against the conventional methods. PMID:20879266

  16. Calcium Oscillations

    PubMed Central

    Dupont, Geneviève; Combettes, Laurent; Bird, Gary S.; Putney, James W.

    2011-01-01

    Calcium signaling results from a complex interplay between activation and inactivation of intracellular and extracellular calcium permeable channels. This complexity is obvious from the pattern of calcium signals observed with modest, physiological concentrations of calcium-mobilizing agonists, which typically present as sequential regenerative discharges of stored calcium, a process referred to as calcium oscillations. In this review, we discuss recent advances in understanding the underlying mechanism of calcium oscillations through the power of mathematical modeling. We also summarize recent findings on the role of calcium entry through store-operated channels in sustaining calcium oscillations and in the mechanism by which calcium oscillations couple to downstream effectors. PMID:21421924

  17. Calcium - urine

    MedlinePlus

    ... best treatment for the most common type of kidney stone , which is made of calcium. This type of ... the kidneys into the urine, which causes calcium kidney stones Sarcoidosis Taking too much calcium Too much production ...

  18. Calcium Carbonate

    MedlinePlus

    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 ...

  19. 8 CFR 103.10 - Precedent decisions.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... General are governed by part 1003 of 8 CFR chapter V. (b) Decisions as precedents. Except as Board... provided in paragraph (c) of this section or 8 CFR 1003.1(h)(2). (d) Publication of Secretary's...

  20. Generation of precedence relations for mechanical assemblies

    NASA Technical Reports Server (NTRS)

    Zhang, Hui; Sanderson, A. C.

    1989-01-01

    Planning of assembly sequences is essential to the manufacturing system design process. Several methodologies have been proposed to represent all the feasible assembly sequences. In this thesis, three algorithms are presented to generate three sets of precedence relations based on all the infeasible assembly tasks, all the infeasible assembly states, and all the feasible assembly sequences, respectively. The equivalence of the resulting sets of precedence relations to the AND/OR graph is established. A new property, the real time property, of a representation of assembly sequences is defined and discussed. A representation of assembly sequences is said to have the real time property, if it is possible to generate the next assembly task by testing locally in the representation, and it will guarantee that the generated assembly task will not lead the assembly sequence to a dead end situation, in which no feasible assembly task can be performed any more. It is shown that the correctness and completeness of one representation can not guarantee the real time property of the representation. It is proven that the directed graph representation and the set of precedence relations based on all the infeasible assembly states have the real time property, while the AND/OR graph representation and the set of precedence relations based on all the infeasible assembly tasks do not have the real time property. Finally in the thesis, the PLEIDEAS system, a PLanning Environment for Integrated DEsign of Assembly Systems, is described and illustrated by an example.

  1. On the Rhetoric and Precedents of Racism.

    ERIC Educational Resources Information Center

    Villanueva, Victor

    1999-01-01

    Considers contribution of rhetorical training of the Aztecs prior to the European conquest as well as other early philosophers from the Americas. Encourages breaking precedent in order to battle racism by looking to rhetorical training developed in the Americas and Puerto Rico in addition to the European thinkers. (SC)

  2. More Than the Rules of Precedence

    ERIC Educational Resources Information Center

    Liang, Yawei

    2005-01-01

    In a fundamental computer-programming course, such as CSE101, questions about how to evaluate an arithmetic expression are frequently used to check if our students know the rules of precedence. The author uses two of our final examination questions to show that more knowledge of computer science is needed to answer them correctly. Furthermore,…

  3. Sleep Disturbance Preceding Completed Suicide in Adolescents

    ERIC Educational Resources Information Center

    Goldstein, Tina R.; Bridge, Jeffrey A.; Brent, David A.

    2008-01-01

    We examined sleep difficulties preceding death in a sample of adolescent suicide completers as compared with a matched sample of community control adolescents. Sleep disturbances were assessed in 140 adolescent suicide victims with a psychological autopsy protocol and in 131 controls with a similar semistructured psychiatric interview. Rates of…

  4. Thrombotic thrombocytopenic purpura preceding systemic lupus erythematosus.

    PubMed Central

    Simeon-Aznar, C P; Cuenca-Luque, R; Fonollosa-Pla, V; Bosch-Gil, J A

    1992-01-01

    The case of a patient admitted with thrombotic thrombocytopenic purpura nine years after developing systemic lupus erythematosus (SLE) is reported. Thrombotic thrombocytopenic purpura associated with SLE has been described on other occasions, but in most patients the diagnosis of SLE precedes that of thrombotic thrombocytopenic purpura. The unusual sequence and the chronological separation of the two diseases is emphasised. PMID:1575591

  5. Calcium - urine

    MedlinePlus

    ... into the urine, which causes calcium kidney stones Sarcoidosis Taking too much calcium Too much production of ... Milk-alkali syndrome Proximal renal tubular acidosis Rickets Sarcoidosis Vitamin D Update Date 5/3/2015 Updated ...

  6. Calcium supplements

    MedlinePlus

    ... SHOULD TAKE CALCIUM SUPPLEMENTS? Calcium is an important mineral for the human body. It helps build and protect your teeth ... absorb calcium. You can get vitamin D from sunlight exposure to your skin and from your diet. Ask your provider whether ...

  7. Threshold of the precedence effect in noise

    PubMed Central

    Freyman, Richard L.; Griffin, Amanda M.; Zurek, Patrick M.

    2014-01-01

    Three effects that show a temporal asymmetry in the influence of interaural cues were studied through the addition of masking noise: (1) The transient precedence effect—the perceptual dominance of a leading transient over a similar lagging transient; (2) the ongoing precedence effect—lead dominance with lead and lag components that extend in time; and (3) the onset capture effect—determination by an onset transient of the lateral position of an otherwise ambiguous extended trailing sound. These three effects were evoked with noise-burst stimuli and were compared in the presence of masking noise. Using a diotic noise masker, detection thresholds for stimuli with lead/lag interaural delays of 0/500 μs were compared to those with 500/0 μs delays. None of the three effects showed a masking difference between those conditions, suggesting that none of the effects is operative at masked threshold. A task requiring the discrimination between stimuli with 500/0 and 0/500 μs interaural delays was used to determine the threshold for each effect in noise. The results showed similar thresholds in noise (10–13 dB SL) for the transient and ongoing precedence effects, but a much higher threshold (33 dB SL) for onset capture of an ambiguous trailing sound. PMID:24815272

  8. Continental warming preceding the Palaeocene-Eocene thermal maximum.

    PubMed

    Secord, Ross; Gingerich, Philip D; Lohmann, Kyger C; Macleod, Kenneth G

    2010-10-21

    Marine and continental records show an abrupt negative shift in carbon isotope values at ∼55.8 Myr ago. This carbon isotope excursion (CIE) is consistent with the release of a massive amount of isotopically light carbon into the atmosphere and was associated with a dramatic rise in global temperatures termed the Palaeocene-Eocene thermal maximum (PETM). Greenhouse gases released during the CIE, probably including methane, have often been considered the main cause of PETM warming. However, some evidence from the marine record suggests that warming directly preceded the CIE, raising the possibility that the CIE and PETM may have been linked to earlier warming with different origins. Yet pre-CIE warming is still uncertain. Disentangling the sequence of events before and during the CIE and PETM is important for understanding the causes of, and Earth system responses to, abrupt climate change. Here we show that continental warming of about 5 °C preceded the CIE in the Bighorn Basin, Wyoming. Our evidence, based on oxygen isotopes in mammal teeth (which reflect temperature-sensitive fractionation processes) and other proxies, reveals a marked temperature increase directly below the CIE, and again in the CIE. Pre-CIE warming is also supported by a negative amplification of δ(13)C values in soil carbonates below the CIE. Our results suggest that at least two sources of warming-the earlier of which is unlikely to have been methane-contributed to the PETM. PMID:20962843

  9. Oral lichen planus preceding concomitant lichen planopilaris.

    PubMed

    Stoopler, Eric T; Alfaris, Sausan; Alomar, Dalal; Alawi, Faizan

    2016-09-01

    Lichen planus (LP) is an immune-mediated mucocutaneous disorder with a wide array of clinical presentations. Oral lichen planus (OLP) is characterized clinically by striae, desquamation, and/or ulceration. Lichen planopilaris (LPP), a variant of LP, affects the scalp, resulting in perifollicular erythema and scarring of cutaneous surfaces accompanied by hair loss. The association between OLP and LPP has been reported previously with scant information on concomitant or sequential disease presentation. We describe a patient with concomitant OLP and LPP, and to the best of our knowledge, this is the first report on OLP preceding the onset of LPP. PMID:27544399

  10. Heart rate dynamics preceding hemorrhage in the intensive care unit.

    PubMed

    Moss, Travis J; Clark, Matthew T; Lake, Douglas E; Moorman, J Randall; Calland, J Forrest

    2015-01-01

    Occult hemorrhage in surgical/trauma intensive care unit (STICU) patients is common and may lead to circulatory collapse. Continuous electrocardiography (ECG) monitoring may allow for early identification and treatment, and could improve outcomes. We studied 4,259 consecutive admissions to the STICU at the University of Virginia Health System. We collected ECG waveform data captured by bedside monitors and calculated linear and non-linear measures of the RR interbeat intervals. We tested the hypothesis that a transfusion requirement of 3 or more PRBC transfusions in a 24 hour period is preceded by dynamical changes in these heart rate measures and performed logistic regression modeling. We identified 308 hemorrhage events. A multivariate model including heart rate, standard deviation of the RR intervals, detrended fluctuation analysis, and local dynamics density had a C-statistic of 0.62. Earlier detection of hemorrhage might improve outcomes by allowing earlier resuscitation in STICU patients. PMID:26342251

  11. [Wide QRS tachycardia preceded by pacemaker spikes].

    PubMed

    Romero, M; Aranda, A; Gómez, F J; Jurado, A

    2014-04-01

    The differential diagnosis and therapeutic management of wide QRS tachycardia preceded by pacemaker spike is presented. The pacemaker-mediated tachycardia, tachycardia fibrillo-flutter in patients with pacemakers, and runaway pacemakers, have a similar surface electrocardiogram, but respond to different therapeutic measures. The tachycardia response to the application of a magnet over the pacemaker could help in the differential diagnosis, and in some cases will be therapeutic, as in the case of a tachycardia-mediated pacemaker. Although these conditions are diagnosed and treated in hospitals with catheterization laboratories using the application programmer over the pacemaker, patients presenting in primary care clinic and emergency forced us to make a diagnosis and treat the haemodynamically unstable patient prior to referral. PMID:23768570

  12. Precedence effects and the evolution of chorusing

    PubMed Central

    Greenfield, M. D.; Tourtellot, M. K.; Snedden, W. A.

    1997-01-01

    The structured choruses produced by rhythmically signalling males in many species of acoustic animals have long-captured the imagination of evolutionary biologists. Though various hypotheses have been forwarded to explain the adaptive significance of such chorusing, none have withstood empirical scrutiny. We suggest instead that alternating and synchronous choruses represent collective epiphenomena resulting from individual males competing to jam each other's signals. These competitions originate in psychoacoustic precedence effects wherein females only orient toward the first call of a sequence, thus selectively favouring males who produce leading calls. Given this perceptual bias, our modelling confirms that a resetting of signal rhythm by neighbours' signals, which generates either alternation or synchrony, is evolutionarily stable provided that resetting includes a relativity adjustment for the velocity of signal transmission and selective attention toward only a subset of signalling neighbours. Signalling strategies in chorusing insects and anurans are consistent with these predicted features.

  13. Cerebral Hypoperfusion Precedes Nausea During Centrifugation

    NASA Technical Reports Server (NTRS)

    Serrador, Jorge M.; Schlegel, Todd T.; Black, F. Owen; Wood, Scott J.

    2004-01-01

    Nausea and motion sickness are important operational concerns for aviators and astronauts. Understanding underlying mechanisms associated with motion sickness may lead to new treatments. The goal of this work was to determine if cerebral blood flow changes precede the development of nausea in motion sick susceptible subjects. Cerebral flow velocity in the middle cerebral artery (transcranial Doppler), blood pressure (Finapres) and end-tidal CO2 were measured while subjects were rotated on a centrifuge (250 degrees/sec). Following 5 min of rotation, subjects were translated 0.504 m off-center, creating a +lGx centripetal acceleration in the nasal-occipital plane. Ten subjects completed the protocol without symptoms while 5 developed nausea (4 while 6ff-center and 1 while rotating on-center). Prior to nausea, subjects had significant increases in blood pressure (+13plus or minus 3 mmHg, P less than 0.05) and cerebrovascular resistance (+46 plus or minus 17%, P less than 0.05) and decreases in cerebral flow velocity both in the second (-13 plus or minus 4%) and last minute (-22 plus or minus 5%) before symptoms (P less than 0.05). In comparison, controls demonstrated no change in blood pressure or cerebrovascular resistance in the last minute of off-center rotation and only a 7 plus or minus 2% decrease in cerebral flow velocity. All subjects had significant hypocapnia (-3.8 plus or minus 0.4 mmHg, P less than 0.05), however this hypocapnia could not fully explain the cerebral hypoperfusion associated with the development of nausea. These data indicate that reductions in cerebral blood flow precede the development of nausea. Further work is necessary to determine what role cerebral hypoperfusion plays in motion sickness and whether cerebral hypoperfusion can be used to predict the development of nausea in susceptible individuals.

  14. Calcium in diet

    MedlinePlus

    ... of calcium dietary supplements include calcium citrate and calcium carbonate. Calcium citrate is the more expensive form of ... the body on a full or empty stomach. Calcium carbonate is less expensive. It is absorbed better by ...

  15. A Solution NMR Investigation into the Early Events of Amelogenin Nanosphere Self-Assembly Initiated with Sodium Chloride or Calcium Chloride

    SciTech Connect

    Buchko, Garry W.; Tarasevich, Barbara J.; Bekhazi, Jacky G.; Snead, Malcolm L.; Shaw, Wendy J.

    2008-12-08

    Using solution-state NMR spectroscopy, new insights into the early intermolecular interactions stabilizing amelogenin supramolecular assembly and the potential role of calcium ions have been discovered. Two-dimensional 1H-15N spectra were recorded for 15N-labeled amelogenin as a function of increasing Ca2+ concentration starting from monomeric conditions. Evidence for protein-protein interactions were observed between residues E18 and E40 in the N-terminus. At higher Ca2+ concentrations there was concurrent involvement of residues in both the N- (Y12-Q56) and the C-terminus (Q144-T171). Neither specific residues nor their stepwise interaction have previously been identified in the initial stages of nanosphere assembly.

  16. Calcium - ionized

    MedlinePlus

    ... levels. These may include abnormal blood levels of albumin or immunoglobulins. Normal Results Children: 4.8 to ... 2016:chap 245. Read More Acute kidney failure Albumin - blood (serum) test Bone tumor Calcium blood test ...

  17. Calcium Test

    MedlinePlus

    ... as thyroid disease , parathyroid disorder , malabsorption , cancer, or malnutrition An ionized calcium test may be ordered when ... albumin , which can result from liver disease or malnutrition , both of which may result from alcoholism or ...

  18. Calcium Calculator

    MedlinePlus

    ... with Sarcopenia Skeletal Rare Disorders Data & Publications Facts and Statistics Vitamin D map Fracture Risk Map Hip Fracture ... Training Courses Working Groups Regional Audits Reports Facts and Statistics Popular content Calcium content of common foods What ...

  19. Calcium Carbonate.

    PubMed

    Al Omari, M M H; Rashid, I S; Qinna, N A; Jaber, A M; Badwan, A A

    2016-01-01

    Calcium carbonate is a chemical compound with the formula CaCO3 formed by three main elements: carbon, oxygen, and calcium. It is a common substance found in rocks in all parts of the world (most notably as limestone), and is the main component of shells of marine organisms, snails, coal balls, pearls, and eggshells. CaCO3 exists in different polymorphs, each with specific stability that depends on a diversity of variables. PMID:26940168

  20. Calcium orthophosphates

    PubMed Central

    Dorozhkin, Sergey V.

    2011-01-01

    The present overview is intended to point the readers’ attention to the important subject of calcium orthophosphates. This type of materials is of special significance for human beings, because they represent the inorganic part of major normal (bones, teeth and antlers) and pathological (i.e., those appearing due to various diseases) calcified tissues of mammals. For example, atherosclerosis results in blood vessel blockage caused by a solid composite of cholesterol with calcium orthophosphates, while dental caries and osteoporosis mean a partial decalcification of teeth and bones, respectively, that results in replacement of a less soluble and harder biological apatite by more soluble and softer calcium hydrogenphosphates. Therefore, the processes of both normal and pathological calcifications are just an in vivo crystallization of calcium orthophosphates. Similarly, dental caries and osteoporosis might be considered an in vivo dissolution of calcium orthophosphates. Thus, calcium orthophosphates hold a great significance for humankind, and in this paper, an overview on the current knowledge on this subject is provided. PMID:23507744

  1. Calcium Hydroxylapatite

    PubMed Central

    Yutskovskaya, Yana Alexandrovna; Philip Werschler, WM.

    2015-01-01

    Background: Calcium hydroxylapatite is one of the most well-studied dermal fillers worldwide and has been extensively used for the correction of moderate-to-severe facial lines and folds and to replenish lost volume. Objectives: To mark the milestone of 10 years of use in the aesthetic field, this review will consider the evolution of calcium hydroxylapatite in aesthetic medicine, provide a detailed injection protocol for a global facial approach, and examine how the unique properties of calcium hydroxylapatite provide it with an important place in today’s market. Methods: This article is an up-to-date review of calcium hydroxylapatite in aesthetic medicine along with procedures for its use, including a detailed injection protocol for a global facial approach by three expert injectors. Conclusion: Calcium hydroxylapatite is a very effective agent for many areas of facial soft tissue augmentation and is associated with a high and well-established safety profile. Calcium hydroxylapatite combines high elasticity and viscosity with an ability to induce long-term collagen formation making it an ideal agent for a global facial approach. PMID:25610523

  2. White Dwarf Convection Preceding Type Ia Supernovae

    NASA Astrophysics Data System (ADS)

    Zingale, Michael; Almgren, A. S.; Bell, J. B.; Malone, C. M.; Nonaka, A.; Woosley, S. E.

    2010-01-01

    In the single degenerate scenario for Type Ia supernovae, a Chandrasekhar mass white dwarf `simmers' for centuries preceding the ultimate explosion. During this period, reactions near the center drive convection throughout most of the interior of the white dwarf. The details of this convective flow determine how the first flames in the white dwarf ignite. Simulating this phase is difficult because the flows are highly subsonic. Using the low Mach number hydrodynamics code, MAESTRO, we present 3-d, full star models of the final hours of this convective phase, up to the point of ignition of a Type Ia supernova. We discuss the details of the convective velocity field and the locations of the initial hot spots. Finally, we show some preliminary results with rotation. Support for this work came from the DOE/Office of Nuclear Physics, grant No. DE-FG02-06ER41448 (Stony Brook), the SciDAC Program of the DOE Office of Mathematics, Information, and Computational Sciences under the DOE under contract No. DE-AC02-05CH11231 (LBNL), and the DOE SciDAC program, under grant No. DE-FC02-06ER41438 (UCSC). We made use of the jaguar machine via a DOE INCITE allocation at the Oak Ridge Leadership Computational Facility.

  3. Animal Detection Precedes Access to Scene Category

    PubMed Central

    Crouzet, Sébastien M.; Joubert, Olivier R.; Thorpe, Simon J.; Fabre-Thorpe, Michèle

    2012-01-01

    The processes underlying object recognition are fundamental for the understanding of visual perception. Humans can recognize many objects rapidly even in complex scenes, a task that still presents major challenges for computer vision systems. A common experimental demonstration of this ability is the rapid animal detection protocol, where human participants earliest responses to report the presence/absence of animals in natural scenes are observed at 250–270 ms latencies. One of the hypotheses to account for such speed is that people would not actually recognize an animal per se, but rather base their decision on global scene statistics. These global statistics (also referred to as spatial envelope or gist) have been shown to be computationally easy to process and could thus be used as a proxy for coarse object recognition. Here, using a saccadic choice task, which allows us to investigate a previously inaccessible temporal window of visual processing, we showed that animal – but not vehicle – detection clearly precedes scene categorization. This asynchrony is in addition validated by a late contextual modulation of animal detection, starting simultaneously with the availability of scene category. Interestingly, the advantage for animal over scene categorization is in opposition to the results of simulations using standard computational models. Taken together, these results challenge the idea that rapid animal detection might be based on early access of global scene statistics, and rather suggests a process based on the extraction of specific local complex features that might be hardwired in the visual system. PMID:23251545

  4. Segmentation precedes face categorization under suboptimal conditions

    PubMed Central

    Van Den Boomen, Carlijn; Fahrenfort, Johannes J.; Snijders, Tineke M.; Kemner, Chantal

    2015-01-01

    Both categorization and segmentation processes play a crucial role in face perception. However, the functional relation between these subprocesses is currently unclear. The present study investigates the temporal relation between segmentation-related and category-selective responses in the brain, using electroencephalography (EEG). Surface segmentation and category content were both manipulated using texture-defined objects, including faces. This allowed us to study brain activity related to segmentation and to categorization. In the main experiment, participants viewed texture-defined objects for a duration of 800 ms. EEG results revealed that segmentation-related responses precede category-selective responses. Three additional experiments revealed that the presence and timing of categorization depends on stimulus properties and presentation duration. Photographic objects were presented for a long and short (92 ms) duration and evoked fast category-selective responses in both cases. On the other hand, presentation of texture-defined objects for a short duration only evoked segmentation-related but no category-selective responses. Category-selective responses were much slower when evoked by texture-defined than by photographic objects. We suggest that in case of categorization of objects under suboptimal conditions, such as when low-level stimulus properties are not sufficient for fast object categorization, segmentation facilitates the slower categorization process. PMID:26074838

  5. The Risks and Benefits of Calcium Supplementation

    PubMed Central

    Kim, Kyoung Min

    2015-01-01

    The association between calcium supplementation and adverse cardiovascular events has recently become a topic of debate due to the publication of two epidemiological studies and one meta-analysis of randomized controlled clinical trials. The reports indicate that there is a significant increase in adverse cardiovascular events following supplementation with calcium; however, a number of experts have raised several issues with these reports such as inconsistencies in attempts to reproduce the findings in other populations and questions concerning the validity of the data due to low compliance, biases in case ascertainment, and/or a lack of adjustment. Additionally, the Auckland Calcium Study, the Women's Health Initiative, and many other studies included in the meta-analysis obtained data from calcium-replete subjects and it is not clear whether the same risk profile would be observed in populations with low calcium intakes. Dietary calcium intake varies widely throughout the world and it is especially low in East Asia, although the risk of cardiovascular events is less prominent in this region. Therefore, clarification is necessary regarding the occurrence of adverse cardiovascular events following calcium supplementation and whether this relationship can be generalized to populations with low calcium intakes. Additionally, the skeletal benefits from calcium supplementation are greater in subjects with low calcium intakes and, therefore, the risk-benefit ratio of calcium supplementation is likely to differ based on the dietary calcium intake and risks of osteoporosis and cardiovascular diseases of various populations. Further studies investigating the risk-benefit profiles of calcium supplementation in various populations are required to develop population-specific guidelines for individuals of different genders, ages, ethnicities, and risk profiles around the world. PMID:25827454

  6. Height changes in the epicentral region preceding the January 17, 1994 Northridge earthquake

    USGS Publications Warehouse

    Castle, Robert O.; Packard, Robert F.; Dinitz, Laura B.

    2000-01-01

    Analysis of the results of repeated levelings through the epicentral region of the Mw 6.7, 1994 Northridge earthquake has disclosed the occurrence of differential uplift in this area that preceded the earthquake. Although the distribution of the relevant vertical-control data is somewhat sparse, in both space and time, those data that we have recovered indicate that this uplift exceeded 0.10 m and peaked 20-25 km west of the 1994 epicenter. While our data also indicate that this deformational event must have occurred during the period 1978-1989, evidence based on the character and magnitude of misclosures developed from 1987 and 1989 surveys argue that the deformation occurred largely during the period 1987-1989. The preseismic vertical-displacement field that preceded the Northridge earthquake is similar in form and, less certainly, magnitude to that which preceded the Mw 6.7, 1971 San Fernando earthquake; other possible, but less significant southern California analogues include the deformational events that preceded the Mw 5.3, 1973 Point Mugu and Mw 5.9, 1987 Whittier Narrows earthquakes. The small but growing number of recognized aseismic deformational episodes that preceded small to moderate magnitude earthquakes in southern California suggests that the deployment of the dense array of continuously recording GPS receivers planned for southern California can be expected to detect and more accurately describe such events than was heretofore possible. Moreover, if the relation between the duration of these deformational anomalies and the magnitudes of any ensuing earthquakes can be much more clearly established, the near perfect temporal control on position afforded by GPS suggests that we may be on the threshold of a realistic earthquake warning system.

  7. Reconciling findings of emotion-induced memory enhancement and impairment of preceding items

    PubMed Central

    Knight, Marisa; Mather, Mara

    2009-01-01

    A large body of work reveals that people remember emotionally arousing information better than neutral information. However, previous research reveals contradictory effects of emotional events on memory for neutral events that precede or follow them: in some studies emotionally arousing items impair memory for immediately preceding or following items and in others arousing items enhance memory for preceding items. By demonstrating both emotion-induced enhancement and impairment, Experiments 1 and 2 clarified the conditions under which these effects are likely to occur. The results suggest that emotion-induced enhancement is most likely to occur for neutral items that: (1) precede (and so are poised to predict the onset of) emotionally arousing items, (2) have high attentional weights at encoding, and (3) are tested after a delay period of a week rather than within the same experiment session. In contrast, emotion-induced impairment is most likely to occur for neutral items near the onset of emotional arousal that are overshadowed by highly activated competing items during encoding. PMID:20001121

  8. Calcium and bones

    MedlinePlus

    Bone strength and calcium ... calcium (as well as phosphorus) to make healthy bones. Bones are the main storage site of calcium in ... your body does not absorb enough calcium, your bones can get weak or will not grow properly. ...

  9. Get Enough Calcium

    MedlinePlus

    ... Calcium Print This Topic En español Get Enough Calcium Browse Sections The Basics Overview Foods and Vitamins ... 2 of 4 sections Take Action! Take Action: Calcium Sources Protect your bones – get plenty of calcium ...

  10. Calcium carbonate overdose

    MedlinePlus

    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 ...

  11. Calcium cyanide

    Integrated Risk Information System (IRIS)

    Jump to main content . Integrated Risk Information System Recent Additions | Contact Us Search : All EPA IRIS • You are here : EPA Home • Research • Environmental Assessment • IRIS • IRIS Summaries Redirect Page As of September 28 , 2010 , the assessment summary for calcium cyanide is included in th

  12. Development of sprite streamers and preceding halos and elves

    NASA Astrophysics Data System (ADS)

    Sanmiya, Y.; Kobayashi, N.; Kudo, T.; Takahashi, Y.; Sato, M.; Shima, Y.; Yamada, T.; NHK Cosmic Shore Project; Stenbaek-Nielsen, H. C.; McHarg, M. G.; Kanmae, T.; Haaland, R.; Yair, Y.; Lyons, W. A.; Cummer, S. A.

    2012-04-01

    The relationship between diffuse glows such as elves and sprite halos and subsequent discrete structure of sprite streamers is considered to have a key to solve the generation mechanism of streamers. However, it's not easy to image at high frame rate both the diffuse and discrete structures simultaneously, since it requires high sensitivity, high spatial resolution and high signal-to-noise ratio. To capture the real spatial structure of TLEs without influence of atmospheric absorption, aircraft would be one of the best solutions. The aircraft can approach thunderstorm up to a few hundred km or less to image TLEs with high spatial resolution and can carry heavy high-speed cameras with huge size data memories. In the period of June 27 - July 10, 2011, a combined aircraft and ground-based campaign, in support of NHK Cosmic Shore project, was carried with two jet airplanes under collaboration between NHK, Japan Broadcasting Corporation, and universities. On 8 nights out of 16 standing-by, the jets took off from the airport near Denver, Colorado, and an airborne high speed camera captured over 40 TLE events at a frame rate of 8300 /sec. Here we introduce the latest analysis of a very complicated time development of sprite streamers and its relationship to the structures of preceding halos and elves, which are always showing some inhomogeneity, suggesting a mechanism to cause the large variation of sprite features.

  13. Short-term seismic quiescence immediately preceding explosions during the 2011 eruption of Telica Volcano, Nicaragua

    NASA Astrophysics Data System (ADS)

    Rodgers, M.; Roman, D. C.; Geirsson, H.; La Femina, P. C.; Muñoz, A.; Tenorio, V.

    2013-12-01

    Telica Volcano, Nicaragua, experienced a VEI 2 eruptive episode from March-June 2011. The eruption consisted of numerous small to moderate ash explosions, many of which were observed visually and recorded by a local broadband seismic network (the TESAND network). Seismicity at Telica during both background and eruptive periods is characterized by generally high and variable rates of low-magnitude volcano-seismic events. Explosions at Telica are also detected seismically and distinguished from volcanic earthquakes by the length of the seismic signal, their emergent nature and 'cigar-shaped' envelope, and broadband spectral content. During the month of May 2011, we identified 16 explosion events on a seismometer located 0.5 km from the crater vent, some of which correlate with visually observed explosions. From May 1-12, ten explosions are apparent in continuous seismic data. During this period, the rate of volcano-seismic events is relatively low (0-20 events/hour with an average of 4 events per hour). Prior to eight of the 10 explosions, there were no detected seismic events within one hour of the explosion. From May 13-31, seven explosions were identified in the continuous seismic data. During this period, the rate of volcano-seismic events is relatively high (0-48 events per hour, with an average of 18 events per hour). In the hour preceding all seven explosions, there were no detected volcano-seismic events. Visual inspection of the continuous seismic data confirms that a strong decrease in the number of volcano-seismic events immediately preceded most of the 2011 explosions at Telica Volcano. We suggest that the apparent short-term decrease in seismicity before explosions at Telica is related to a cycle of pressure buildup and release in the shallow magmatic-hydrothermal system, with an increase in pressure prior to the explosions both resulting from and reflecting constriction of gas pathways.

  14. 10 CFR 205.11 - Order of precedence.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 3 2010-01-01 2010-01-01 false Order of precedence. 205.11 Section 205.11 Energy DEPARTMENT OF ENERGY OIL ADMINISTRATIVE PROCEDURES AND SANCTIONS General Provisions § 205.11 Order of precedence. (a) If there is any conflict or inconsistency between the provisions of this part and any...

  15. 48 CFR 3452.215-33 - Order of precedence.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 7 2010-10-01 2010-10-01 false Order of precedence. 3452.215-33 Section 3452.215-33 Federal Acquisition Regulations System DEPARTMENT OF EDUCATION ACQUISITION REGULATION CLAUSES AND FORMS SOLICITATION PROVISIONS AND CONTRACT CLAUSES Texts of Provisions and Clauses 3452.215-33 Order of precedence....

  16. 26 CFR 1.665(e)-1 - Preceding taxable year.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 26 Internal Revenue 8 2010-04-01 2010-04-01 false Preceding taxable year. 1.665(e)-1 Section 1.665... (CONTINUED) INCOME TAXES Treatment of Excess Distributions of Trusts Applicable to Taxable Years Beginning Before January 1, 1969 § 1.665(e)-1 Preceding taxable year. (a) Definition. For purposes of subpart...

  17. 26 CFR 1.665(e)-1 - Preceding taxable year.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 26 Internal Revenue 8 2011-04-01 2011-04-01 false Preceding taxable year. 1.665(e)-1 Section 1.665... (CONTINUED) INCOME TAXES (CONTINUED) Treatment of Excess Distributions of Trusts Applicable to Taxable Years Beginning Before January 1, 1969 § 1.665(e)-1 Preceding taxable year. (a) Definition. For purposes...

  18. 26 CFR 1.665(e)-1 - Preceding taxable year.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 26 Internal Revenue 8 2012-04-01 2012-04-01 false Preceding taxable year. 1.665(e)-1 Section 1.665... (CONTINUED) INCOME TAXES (CONTINUED) Treatment of Excess Distributions of Trusts Applicable to Taxable Years Beginning Before January 1, 1969 § 1.665(e)-1 Preceding taxable year. (a) Definition. For purposes...

  19. 26 CFR 1.665(e)-1 - Preceding taxable year.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 26 Internal Revenue 8 2014-04-01 2014-04-01 false Preceding taxable year. 1.665(e)-1 Section 1.665... (CONTINUED) INCOME TAXES (CONTINUED) Treatment of Excess Distributions of Trusts Applicable to Taxable Years Beginning Before January 1, 1969 § 1.665(e)-1 Preceding taxable year. (a) Definition. For purposes...

  20. The control of calcium release in heart muscle.

    PubMed

    Cannell, M B; Cheng, H; Lederer, W J

    1995-05-19

    The control of calcium release from intracellular stores (the sarcoplasmic reticulum) in cardiac muscle was examined with the use of a confocal microscope and voltage clamp techniques. Depolarization evoked graded calcium release by altering the extent of spatial and temporal summation of elementary calcium release events called "calcium sparks." These evoked sparks were triggered by local L-type calcium channel currents in a stochastic manner, were similar at different potentials, and resembled spontaneous calcium sparks. Once triggered, the calcium release from the sarcoplasmic reticulum during a calcium spark was independent of the duration of the triggering calcium influx. These results were used to develop a unifying model for cardiac excitation-contraction coupling that explains the large (but paradoxically stable) amplification of the trigger calcium influx by a combination of digital and analog behavior. PMID:7754384

  1. The beginning of the calcium transient in rat embryonic heart.

    PubMed

    Kobayashi, Takeshi; Maeda, Sachiko; Ichise, Nobutoshi; Sato, Tatsuya; Iwase, Takehito; Seki, Sumihiko; Yamada, Yoichi; Tohse, Noritsugu

    2011-03-01

    Although many researchers have tried to observe the beginning of the heartbeat, no study has shown the beginning of the calcium transient. Here, we evaluate the beginning of the calcium transient in the Wistar rat heart. We first tried to reveal when the heart of the Wistar rat begins to contract because no previous study has evaluated the beginning of the heartbeat in Wistar rats. Observation of embryos transferred to a small incubator mounted on a microscope revealed that the heart primordium, the so-called cardiac crescent, began to contract at embryonic day 9.99-10.13. Observation of embryos loaded with fluo-3 AM revealed that the beginning of the calcium transient precedes the initiation of contraction which precedes the appearance of the linear heart tube. Nifedipine (1 μM), but not ryanodine (1 μM), abolished the calcium transients. These results indicate that calcium transients in the early embryonic period involve exclusively calcium entry through L-type calcium channels in contrast to the situation in mature hearts. This study provides the first demonstration of the relationship between morphological changes in the heart primordium and the beginning of the calcium transient and contraction. PMID:21267689

  2. Transient isolated brainstem symptoms preceding posterior circulation stroke: a population-based study

    PubMed Central

    Paul, Nicola LM; Simoni, Michela; Rothwell, Peter M

    2013-01-01

    Summary Background Transient isolated brainstem symptoms (eg, isolated vertigo, dysarthria, diplopia) are not consistently classified as transient ischaemic attacks (TIAs) and data for prognosis are limited. If some of these transient neurological attacks (TNAs) are due to vertebrobasilar ischaemia, then they should be common during the days and weeks preceding posterior circulation strokes. We aimed to assess the frequency of TNAs before vertebrobasilar ischaemic stroke. Methods We studied all potential ischaemic events during the 90 days preceding an ischaemic stroke in patients ascertained within a prospective, population-based incidence study in Oxfordshire, UK (Oxford Vascular Study; 2002–2010) and compared rates of TNA preceding vertebrobasilar stroke versus carotid stroke. We classified the brainstem symptoms isolated vertigo, vertigo with non-focal symptoms, isolated double vision, transient generalised weakness, and binocular visual disturbance as TNAs in the vertebrobasilar territory; atypical amaurosis fugax and limb-shaking as TNAs in the carotid territory; and isolated slurred speech, migraine variants, transient confusion, and hemisensory tingling symptoms as TNAs in uncertain territory. Findings Of the 1141 patients with ischaemic stroke, vascular territory was categorisable in 1034 (91%) cases, with 275 vertebrobasilar strokes and 759 carotid strokes. Isolated brainstem TNAs were more frequent before a vertebrobasilar stroke (45 of 275 events) than before a carotid stroke (10 of 759; OR 14·7, 95% CI 7·3–29·5, p<0·0001), particularly during the preceding 2 days (22 of 252 before a vertebrobasilar stroke vs two of 751 before a carotid stroke, OR 35·8, 8·4–153·5, p<0·0001). Of all 59 TNAs preceding (median 4 days, IQR 1–30) vertebrobasilar stroke, only five (8%) fulfilled the National Institute of Neurological Disorders and Stroke (NINDS) criteria for TIA. The other 54 cases were isolated vertigo (n=23), non-NINDS binocular visual

  3. Evaluation of a potential clinical interaction between ceftriaxone and calcium.

    PubMed

    Steadman, Emily; Raisch, Dennis W; Bennett, Charles L; Esterly, John S; Becker, Tischa; Postelnick, Michael; McKoy, June M; Trifilio, Steve; Yarnold, Paul R; Scheetz, Marc H

    2010-04-01

    In April 2009, the FDA retracted a warning asserting that ceftriaxone and intravenous calcium products should not be coadministered to any patient to prevent precipitation events leading to end-organ damage. Following that announcement, we sought to evaluate if the retraction was justified. A search of the FDA Adverse Event Reporting System was conducted to identify any ceftriaxone-calcium interactions that resulted in serious adverse drug events. Ceftazidime-calcium was used as a comparator agent. One hundred four events with ceftriaxone-calcium and 99 events with ceftazidime-calcium were identified. Adverse drug events were recorded according to the listed description of drug involvement (primary or secondary suspect) and were interpreted as probable, possible, unlikely, or unrelated. For ceftriaxone-calcium-related adverse events, 7.7% and 20.2% of the events were classified as probable and possible for embolism, respectively. Ceftazidime-calcium resulted in fewer probable embolic events (4%) but more possible embolic events (30.3%). Among cases that considered ceftriaxone or ceftazidime and calcium as the primary or secondary drug, one case was classified as a probable embolic event. That patient received ceftriaxone-calcium and died, although an attribution of causality was not possible. Our analysis suggests a lack of support for the occurrence of ceftriaxone-calcium precipitation events in adults. The results of the current analysis reinforce the revised FDA recommendations suggesting that patients >28 days old may receive ceftriaxone and calcium sequentially and provide a transparent and reproducible methodology for such evaluations. PMID:20086152

  4. Stimulus-preceding negativity represents a conservative response tendency

    PubMed Central

    Hirao, Takahiro; Murphy, Timothy I.

    2016-01-01

    Humans tend to be conservative and typically will retain their initial decision even if an option to change is provided. We investigated whether the stimulus-preceding negativity (SPN), an event-related potential associated with the affective-motivational anticipation of feedback in gambling tasks, represents the strong response tendency to retain an initial decision. We compared SPNs in three different card-gambling tasks wherein the participants were given the opportunity to change their initial decision after they chose one of three cards. In two of these tasks, the winning probability was equiprobable (1/3 and 1/2, respectively) whether or not the participants changed their initial decision. However, in the Monty Hall dilemma task, changing the initial decision stochastically doubled the probability of winning (2/3) compared with retaining (1/3). In this counterintuitive probabilistic dilemma task, after the participant chose an option among three cards, a nonreward (losing) option is revealed. Then, the participants are offered a chance to change their mind and asked to make their final decision: to retain their initial choice or change to the alternate option. In all tasks, maintenance of previous behaviors was observed, although the rate of retaining earlier choices tended to be lower in the Monty Hall dilemma task than in the other two tasks. The SPNs were larger on retain trials than on change trials irrespective of task. These results suggest that underlying brain activities associated with the strong tendency to retain the initial decision can be observed by the SPN and thus it reflects expectancy of outcomes in terms of self-chosen behaviors. PMID:26626414

  5. Calcium and Vitamin D

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Calcium is required for the bone formation phase of bone remodeling. Typically about 5 nmol (200 mg) of calcium is removed from the adult skeleton and replaced each day. To supply this amount, one would need to consume about 600 mg of calcium, since calcium is not very efficiently absorbed. Calcium ...

  6. Calcium and bones (image)

    MedlinePlus

    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 ...

  7. Calcium source (image)

    MedlinePlus

    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 ...

  8. Coronary Calcium Scan

    MedlinePlus

    ... the NHLBI on Twitter. What Is a Coronary Calcium Scan? A coronary calcium scan is a test ... you have calcifications in your coronary arteries. Coronary Calcium Scan Figure A shows the position of the ...

  9. Calcium hydroxide poisoning

    MedlinePlus

    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 ...

  10. [Health benefits and demerits of calcium nutrition or supplementation in older people].

    PubMed

    Shiraki, Masataka

    2015-10-01

    The benefit of calcium nutrition for health has been believed for a long time. In fact, higher calcium intake is associated with reduction of blood pressure, rate of bone loss after menopause and mild risk reduction of fracture. Since calcium intake from food has not been achieved to be the recommended level, calcium supplementation is widely used especially in the US. However, calcium supplementation has been reported to increase in vascular events, recently. On the other hand, calcium nutrition from foods have not been reported any harmful effect on health. Therefore, calcium effects on health seemed to be composite effects of other nutrients taking together with calcium. PMID:26536675

  11. ATP release due to Thy-1–integrin binding induces P2X7-mediated calcium entry required for focal adhesion formation

    PubMed Central

    Henríquez, Mauricio; Herrera-Molina, Rodrigo; Valdivia, Alejandra; Alvarez, Alvaro; Kong, Milene; Muñoz, Nicolás; Eisner, Verónica; Jaimovich, Enrique; Schneider, Pascal; Quest, Andrew F. G.; Leyton, Lisette

    2011-01-01

    Thy-1, an abundant mammalian glycoprotein, interacts with αvβ3 integrin and syndecan-4 in astrocytes and thus triggers signaling events that involve RhoA and its effector p160ROCK, thereby increasing astrocyte adhesion to the extracellular matrix. The signaling cascade includes calcium-dependent activation of protein kinase Cα upstream of Rho; however, what causes the intracellular calcium transients required to promote adhesion remains unclear. Purinergic P2X7 receptors are important for astrocyte function and form large non-selective cation pores upon binding to their ligand, ATP. Thus, we evaluated whether the intracellular calcium required for Thy-1-induced cell adhesion stems from influx mediated by ATP-activated P2X7 receptors. Results show that adhesion induced by the fusion protein Thy-1-Fc was preceded by both ATP release and sustained intracellular calcium elevation. Elimination of extracellular ATP with Apyrase, chelation of extracellular calcium with EGTA, or inhibition of P2X7 with oxidized ATP, all individually blocked intracellular calcium increase and Thy-1-stimulated adhesion. Moreover, Thy-1 mutated in the integrin-binding site did not trigger ATP release, and silencing of P2X7 with specific siRNA blocked Thy-1-induced adhesion. This study is the first to demonstrate a functional link between αvβ3 integrin and P2X7 receptors, and to reveal an important, hitherto unanticipated, role for P2X7 in calcium-dependent signaling required for Thy-1-stimulated astrocyte adhesion. PMID:21502139

  12. Altered Calcium Signaling Following Traumatic Brain Injury

    PubMed Central

    Weber, John T.

    2012-01-01

    Cell death and dysfunction after traumatic brain injury (TBI) is caused by a primary phase, related to direct mechanical disruption of the brain, and a secondary phase which consists of delayed events initiated at the time of the physical insult. Arguably, the calcium ion contributes greatly to the delayed cell damage and death after TBI. A large, sustained influx of calcium into cells can initiate cell death signaling cascades, through activation of several degradative enzymes, such as proteases and endonucleases. However, a sustained level of intracellular free calcium is not necessarily lethal, but the specific route of calcium entry may couple calcium directly to cell death pathways. Other sources of calcium, such as intracellular calcium stores, can also contribute to cell damage. In addition, calcium-mediated signal transduction pathways in neurons may be perturbed following injury. These latter types of alterations may contribute to abnormal physiology in neurons that do not necessarily die after a traumatic episode. This review provides an overview of experimental evidence that has led to our current understanding of the role of calcium signaling in death and dysfunction following TBI. PMID:22518104

  13. Cortical Low-Frequency Power and Progressive Phase Synchrony Precede Successful Memory Encoding

    PubMed Central

    Haque, Rafi U.; Wittig, John H.; Damera, Srikanth R.; Inati, Sara K.

    2015-01-01

    Neural activity preceding an event can influence subsequent memory formation, yet the precise cortical dynamics underlying this activity and the associated cognitive states remain unknown. We investigate these questions here by examining intracranial EEG recordings as 28 participants with electrodes placed for seizure monitoring participated in a verbal paired-associates memory task. We found that, preceding successfully remembered word pairs, an orientation cue triggered a low-frequency 2–4 Hz phase reset in the right temporoparietal junction with concurrent increases in low-frequency power across cortical regions that included the prefrontal cortex and left temporal lobe. Regions that exhibited a significant increase in 2–4 Hz power were functionally bound together through progressive low-frequency 2–4 Hz phase synchrony. Our data suggest that the interaction between power and phase synchrony reflects the engagement of attentional networks that in large part determine the extent to which memories are successfully encoded. SIGNIFICANCE STATEMENT Here we investigate the spatiotemporal cortical dynamics that precede successful memory encoding. Using intracranial EEG, we observed significant changes in oscillatory power, intertrial phase consistency, and pairwise phase synchrony that predict successful encoding. Our data suggest that the interaction between power and phase synchrony reflects the engagement of attentional networks that in large part determine the extent to which memories are successfully encoded. PMID:26446212

  14. Polysomnographic findings in nights preceding a migraine attack.

    PubMed

    Göder, R; Fritzer, G; Kapsokalyvas, A; Kropp, P; Niederberger, U; Strenge, H; Gerber, W D; Aldenhoff, J B

    2001-02-01

    Sleep recordings were performed in eight patients to analyse sleep alterations preceding migraine attacks. Polysomnographic recordings from nights before an attack were compared with nights without following migraine. We analysed standard sleep parameters and electroencephalogram (EEG) power spectra. The main findings preceding migraine attacks were a significant decrease in the number of arousals, a decrease in rapid eye movement (REM) density, a significant decrease of beta power in the slow wave sleep, and a decrease of alpha power during the first REM period. The results suggest a decrease in cortical activation during sleep preceding migraine attacks. According to the models of sleep regulation, alterations in the function of aminergic or cholinergic brainstem nuclei have to be discussed. PMID:11298661

  15. Periodic increases in elongation rate precede increases in cytosolic Ca2+ during pollen tube growth.

    PubMed

    Messerli, M A; Créton, R; Jaffe, L F; Robinson, K R

    2000-06-01

    Pollen tubes grown in vitro require an intracellular tip-high gradient of Ca2+ in order to elongate. Moreover, after about 2 h in vitro both the tip Ca2+ and the elongation rate of lily tubes begin to oscillate regularly with large amplitudes. This raises the question of the phase relation between these two oscillations. Previous studies lacked the temporal resolution to accurately establish this relationship. We have studied these oscillations with a newly developed, high temporal resolution system and the complementary use of both luminescent and fluorescent calcium reporters. We hereby show that the periodic increases in elongation rate during oscillatory growth of Lilium longiflorum pollen tubes clearly precede those in subtip calcium and do so by 4.1 +/- 0.2 s out of average periods of 38.7 +/- 1.8 s. Also, by collecting images of the light output of aequorin, we find that the magnitude of the [Ca2+] at the tip oscillates between 3 and 10 microM, which is considerably greater than that reported by fluorescent indicators. We propose an explanatory model that features cyclic growth and secretion in which growth oscillations give rise to secretion that is essential for the subsequent growth oscillation. We also critically compile data on L. longiflorum stylar growth rates, which show little variation from in vitro rates of pollen tubes grown in optimal medium. PMID:10885748

  16. The Role of Sexual Precedence in Verbal Sexual Coercion

    ERIC Educational Resources Information Center

    Livingston, Jennifer A.; Buddie, Amy M.; Testa, Maria; VanZile-Tamsen, Carol

    2004-01-01

    Experiences of verbal sexual coercion are common and have potential for negative consequences, yet are not well understood. This study used qualitative and descriptive statistics to examine verbal sexual coercion experiences among a community sample of 114 women and explored the role of sexual precedence in these experiences. Analyses revealed…

  17. Episodic Mood Changes Preceding an Exacerbation of Multiple Sclerosis

    PubMed Central

    Sharma, Priya; Morrow, Sarah A.; Owen, Richard J.

    2015-01-01

    Multiple sclerosis is a neurologic inflammatory disease that can manifest with psychiatric symptoms. Although depression is the most common psychiatric diagnosis in patients with multiple sclerosis, how depression develops is not fully understood. We present the case of an individual who displayed episodic mood changes preceding an exacerbation of multiple sclerosis symptoms. The clinical and research implications of this association are discussed. PMID:26835163

  18. Metrical expectations from preceding prosody influence perception of lexical stress.

    PubMed

    Brown, Meredith; Salverda, Anne Pier; Dilley, Laura C; Tanenhaus, Michael K

    2015-04-01

    Two visual-world experiments tested the hypothesis that expectations based on preceding prosody influence the perception of suprasegmental cues to lexical stress. The results demonstrate that listeners' consideration of competing alternatives with different stress patterns (e.g., 'jury/gi'raffe) can be influenced by the fundamental frequency and syllable timing patterns across material preceding a target word. When preceding stressed syllables distal to the target word shared pitch and timing characteristics with the first syllable of the target word, pictures of alternatives with primary lexical stress on the first syllable (e.g., jury) initially attracted more looks than alternatives with unstressed initial syllables (e.g., giraffe). This effect was modulated when preceding unstressed syllables had pitch and timing characteristics similar to the initial syllable of the target word, with more looks to alternatives with unstressed initial syllables (e.g., giraffe) than to those with stressed initial syllables (e.g., jury). These findings suggest that expectations about the acoustic realization of upcoming speech include information about metrical organization and lexical stress and that these expectations constrain the initial interpretation of suprasegmental stress cues. These distal prosody effects implicate online probabilistic inferences about the sources of acoustic-phonetic variation during spoken-word recognition. PMID:25621583

  19. 48 CFR 819.202-72 - Order of precedence. [Reserved

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 48 Federal Acquisition Regulations System 5 2014-10-01 2014-10-01 false Order of precedence. 819.202-72 Section 819.202-72 Federal Acquisition Regulations System DEPARTMENT OF VETERANS AFFAIRS SOCIOECONOMIC PROGRAMS SMALL BUSINESS PROGRAMS Policies 819.202-72 Order of...

  20. Metrical expectations from preceding prosody influence perception of lexical stress

    PubMed Central

    Brown, Meredith; Salverda, Anne Pier; Dilley, Laura C.; Tanenhaus, Michael K.

    2015-01-01

    Two visual-world experiments tested the hypothesis that expectations based on preceding prosody influence the perception of suprasegmental cues to lexical stress. The results demonstrate that listeners’ consideration of competing alternatives with different stress patterns (e.g., ‘jury/gi’raffe) can be influenced by the fundamental frequency and syllable timing patterns across material preceding a target word. When preceding stressed syllables distal to the target word shared pitch and timing characteristics with the first syllable of the target word, pictures of alternatives with primary lexical stress on the first syllable (e.g., jury) initially attracted more looks than alternatives with unstressed initial syllables (e.g., giraffe). This effect was modulated when preceding unstressed syllables had pitch and timing characteristics similar to the initial syllable of the target word, with more looks to alternatives with unstressed initial syllables (e.g., giraffe) than to those with stressed initial syllables (e.g., jury). These findings suggest that expectations about the acoustic realization of upcoming speech include information about metrical organization and lexical stress, and that these expectations constrain the initial interpretation of suprasegmental stress cues. These distal prosody effects implicate on-line probabilistic inferences about the sources of acoustic-phonetic variation during spoken-word recognition. PMID:25621583

  1. [Do cows drink calcium?].

    PubMed

    Geishauser, T; Lechner, S; Plate, I; Heidemann, B

    2008-03-01

    The objective of this study was to investigate how well cows drink the Propeller calcium drink, and it's effect on blood calcium concentration. Drinking was tested in 120 cows right after calving, before cows drank anything else. 60 cows each were offered 20 liters of Propeller calcium drink or 20 liters of water. Cows drank the Propeller as good as water. 72% of all cows drank all 20 liters, 18% drank on average 8.2 liters and 10% drank less than 1 liter. Blood calcium concentration was studied in 16 cows right after calving. Eight cows each were offered 20 liters of Propeller calcium drink or no calcium drink. Blood calcium significantly increased ten minutes after Propeller intake and stayed significantly elevated for 24 hours. Without calcium drink blood calcium levels decreased significantly. Advantages of the new Propeller calcium drink over calcium gels or boli could be that cows now drink calcium themselves and that the Propeller increases blood calcium concentration rapidly and long lasting. PMID:18429501

  2. Extended precedence preservative crossover for job shop scheduling problems

    NASA Astrophysics Data System (ADS)

    Ong, Chung Sin; Moin, Noor Hasnah; Omar, Mohd

    2013-04-01

    Job shop scheduling problems (JSSP) is one of difficult combinatorial scheduling problems. A wide range of genetic algorithms based on the two parents crossover have been applied to solve the problem but multi parents (more than two parents) crossover in solving the JSSP is still lacking. This paper proposes the extended precedence preservative crossover (EPPX) which uses multi parents for recombination in the genetic algorithms. EPPX is a variation of the precedence preservative crossover (PPX) which is one of the crossovers that perform well to find the solutions for the JSSP. EPPX is based on a vector to determine the gene selected in recombination for the next generation. Legalization of children (offspring) can be eliminated due to the JSSP representation encoded by using permutation with repetition that guarantees the feasibility of chromosomes. The simulations are performed on a set of benchmarks from the literatures and the results are compared to ensure the sustainability of multi parents recombination in solving the JSSP.

  3. Endogenous lipoid pneumonia preceding diagnosis of pulmonary alveolar proteinosis.

    PubMed

    Antoon, James W; Hernandez, Michelle L; Roehrs, Phillip A; Noah, Terry L; Leigh, Margaret W; Byerley, Julie S

    2016-03-01

    Pulmonary alveolar proteinosis (PAP) is an under-reported and under-diagnosed condition, with a high percentage of cases found on autopsy or late stage disease. The etiology of PAP includes genetic, primary (anti-granulocyte-macrophage colony-stimulating factor antibodies) and secondary (oncologic, rheumatologic, infectious, chemical and immunologic) causes. Here, we present the first reported pediatric case of endogenous lipoid pneumonia and non-specific interstitial pneumonitis preceding the development of PAP. PMID:25103284

  4. Foreshock Patterns Preceding Great Earthquakes in the Subduction Zone of Chile

    NASA Astrophysics Data System (ADS)

    Papadopoulos, G. A.; Minadakis, G.

    2016-07-01

    Foreshock activity is considered as one of the most promising precursory changes for the main shock prediction in the short term. Averaging over several foreshock sequences has shown that foreshocks are characterized by distinct 3D patterns: their epicenters move towards the main shock epicenter, event count accelerates, and b-value drops. However, these space-time-size patterns were verified so far only in a very few individual cases mainly due to inadequate seismicity catalogue data. We have investigated 3D foreshock patterns before the M w 8.8 Maule in 27 February 2010, M w 8.1 Iquique in 1 April 2014, and M w 8.4 Illapel in 16 September 2015 great earthquakes in the Chile subduction zone. To avoid biased results, no a priori spatiotemporal definitions of foreshocks were inserted. The procedure was based on pattern recognition from statistically significant seismicity changes in the three domains. The pattern recognition in one domain was independent of the pattern recognition in another domain. We found and verified with two independent catalogue data sets (CSN, IPOC) that within a critical area of ca. 65 km from the main shock epicenter, the 2014 event was preceded by distinct foreshock 3D patterns. A nearly weak foreshock stage (20 January-14 March 2014) was followed by a main-strong stage (15 March-1 April 2014) highly significant in all domains, although foreshock activity slightly decreased in about the last 5 days. Seismic moment release also accelerated in the last stage due to the occurrence of a cluster of very strong foreshock events. Foreshock activity very likely occurred in the hanging-wall fault domain on the South American Plate overriding Nazca Plate. The 2014 foreshock activity was quite similar to the one preceding the 6 Apr. 2009 L' Aquila (Italy) M w 6.3 earthquake associated with normal faulting. Using the 2014 earthquake as a reference event, we observed that similar foreshock 3D patterns preceded the 2010 and 2015 earthquakes within

  5. Fenoprofen calcium overdose

    MedlinePlus

    ... 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 ...

  6. Calcium channel blocker overdose

    MedlinePlus

    ... this 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 ...

  7. Calcium and Vitamin D

    MedlinePlus

    ... to your weekly shopping list. Produce Serving Size Estimated Calcium* Collard greens, frozen 8 oz 360 mg ... Oranges 1 whole 55 mg Seafood Serving Size Estimated Calcium* Sardines, canned with bones 3 oz 325 ...

  8. Calcium and bones (image)

    MedlinePlus

    Calcium is one of the most important minerals for the growth, maintenance, and reproduction of the human body. Bones, like other tissues in the body, are continually being re-formed and incorporate calcium into their ...

  9. Fenoprofen calcium overdose

    MedlinePlus

    Fenoprofen calcium is a type of medicine called a nonsteroidal anti-inflammatory drug. It is a prescription pain medicine used to relieve symptoms of arthritis . Fenoprofen calcium overdose occurs when someone takes more than the ...

  10. Frequency and Relative Prevalence of Calcium Blips and Puffs in a Model of Small IP3R Clusters

    PubMed Central

    Qi, Hong; Huang, Yandong; Rüdiger, Sten; Shuai, Jianwei

    2014-01-01

    In this work, we model the local calcium release from clusters with a few inositol 1,4,5-trisphosphate receptor (IP3R) channels, focusing on the stochastic process in which an open channel either triggers other channels to open (as a puff) or fails to cause any channel to open (as a blip). We show that there are linear relations for the interevent interval (including blips and puffs) and the first event latency against the inverse cluster size. However, nonlinearity is found for the interpuff interval and the first puff latency against the inverse cluster size. Furthermore, the simulations indicate that the blip fraction among all release events and the blip frequency are increasing with larger basal [Ca2+], with blips in turn giving a growing contribution to basal [Ca2+]. This result suggests that blips are not just lapses to trigger puffs, but they may also possess a biological function to contribute to the initiation of calcium waves by a preceding increase of basal [Ca2+] in cells that have small IP3R clusters. PMID:24896114

  11. Strontium Substitution for Calcium in Lithogenesis

    PubMed Central

    Blaschko, Sarah D.; Chi, Thomas; Miller, Joe; Flechner, Lawrence; Fakra, Sirine; Kapahi, Pankaj; Kahn, Arnold; Stoller, Marshall L.

    2013-01-01

    Purpose Strontium has chemical similarity to calcium, which enables the replacement of calcium by strontium in biomineralization processes. Incorporating strontium into human bone and teeth has been studied extensively but little research has been performed of the incorporation of strontium into urinary calculi. We used synchrotron based x-ray fluorescence and x-ray absorption techniques to examine the presence of strontium in different types of human kidney stones. Materials and Methods Multiple unique human stone samples were obtained via consecutive percutaneous nephrolithotomies/ureteroscopies. A portion of each stone was sent for standard laboratory analysis and a portion was retained for x-ray fluorescence and x-ray absorption measurements. X-ray fluorescence and x-ray absorption measurements determined the presence, spatial distribution and speciation of strontium in each stone sample. Results Traditional kidney stone analyses identified calcium oxalate, calcium phosphate, uric acid and cystine stones. X-ray fluorescence measurements identified strontium in all stone types except pure cystine. X-ray fluorescence elemental mapping of the samples revealed co-localization of calcium and strontium. X-ray absorption measurements of the calcium phosphate stone showed strontium predominately present as strontium apatite. Conclusions Advanced x-ray fluorescence imaging identified strontium in all calcium based stones, present as strontium apatite. This finding may be critical since apatite is thought to be the initial nidus for calcium stone formation. Strontium is not identified by standard laboratory stone analyses. Its substitution for calcium can be reliably identified in stones from multiple calcium based stone formers, which may offer opportunities to gain insight into early events in lithogenesis. PMID:23260568

  12. Environmental stress and 3-day eventing: effects of altitude.

    PubMed

    Foreman, J H; Waldsmith, J K; Lalum, R B

    1999-07-01

    Three-day event horses are subject to various external environmental stresses including changes in ambient temperature, humidity, altitude, and test severity. Considerable research on the adverse effects of increased heat and humidity preceded the 1996 Olympic Summer Games in Atlanta, Georgia USA, but no research has been done previously on the effects of altitude on 3-day eventing. Physical and venous blood gas data were collected on horses (n = 24) competing in the High Prairie Preliminary (CCN*) and Intermediate (CCN**) 3-day events and Preliminary Horse Trials in Parker, Colorado (1900 m above sea level). Despite the increased altitude, only post exercise rectal temperature and pH were higher (P < 0.05) whereas heart rate (HR), [K+], and ionized calcium (ICa++) were lower (P < 0.05) in 3-day event horses compared to horse trial horses. All other variables (respiratory rate [RR], PCV, [Hb], PCO2, [tCO2], [HCO3-], BE, and [Na+]) were not different between groups (P > 0.05). When these preliminary horse trial horses in Colorado were compared to those previously studied at preliminary horse trials at sea level in Arizona, post exercise HR and RR were higher (P < 0.05) and pH, PCO2, [tCO2], [HCO3-], BE and [iCa++] were lower (P < 0.05) at altitude. These data show that increased altitude (1900 m above sea level) was more stressful for 3-day event horses, but did not result in the severe physiological changes and inability to complete prescribed exercise tests seen in previous studies with increased heat and humidity. It is clear from these and previous data that increased heat and humidity are the more important environmental stressors in 3-day eventing. PMID:10659288

  13. Calcium and magnesium disorders.

    PubMed

    Goff, Jesse P

    2014-07-01

    Hypocalcemia is a clinical disorder that can be life threatening to the cow (milk fever) and predisposes the animal to various other metabolic and infectious disorders. Calcium homeostasis is mediated primarily by parathyroid hormone, which stimulates bone calcium resorption and renal calcium reabsorption. Parathyroid hormone stimulates the production of 1,25-dihydroxyvitamin D to enhance diet calcium absorption. High dietary cation-anion difference interferes with tissue sensitivity to parathyroid hormone. Hypomagnesemia reduces tissue response to parathyroid hormone. PMID:24980727

  14. Calcium and Mitosis

    NASA Technical Reports Server (NTRS)

    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.

  15. A comparative study of calcium absorption following a single serving administration of calcium carbonate powder versus calcium citrate tablets in healthy premenopausal women

    PubMed Central

    Wang, Haiyuan; Bua, Peter; Capodice, Jillian

    2014-01-01

    Background Calcium is an essential mineral often taken as a daily, long-term nutritional supplement. Data suggests that once-daily dosing is important with regard to long-term compliance of both drugs and nutritional supplements. Objective This study was undertaken to compare the bioavailability of a single serving of two calcium supplements in healthy, premenopausal women. Design A two-period, crossover bioavailability study of a single serving of calcium citrate tablets (two tablets=500 mg calcium) versus a single serving of calcium carbonate powder (one packet of powder=1,000 mg calcium) was performed in healthy women aged between 25 and 45. All subjects were on a calcium-restricted diet 7 days prior to testing and fasted for 12 h before being evaluated at 0, 1, 2, and 4 h after oral administration of the test agents. Blood measurements for total and ionized calcium and parathyroid hormone were performed and adverse events were monitored. Results Twenty-three women were evaluable with a mean age of 33.2±8.71. Results showed that administration of a single serving of a calcium carbonate powder resulted in greater absorption in total and ionized calcium versus a single serving of calcium citrate tablets at 4 h (4.25±0.21 vs. 4.16±0.16, p=0.001). There were minimal side effects and no reported serious adverse events. Conclusions This study shows that a single serving of a calcium carbonate powder is more bioavailable than a single serving of calcium citrate tablets. This may be beneficial for long-term compliance. PMID:24772062

  16. Calcium and Vitamin D

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This chapter describes the roles of calcium and vitamin D in bone health. Calcium is required for the bone formation phase of bone remodeling and it also affects bone mass through its impact on the remodeling rate. Typically, about 5 nmol (200 mg) of calcium is removed from the adult skeleton and ...

  17. Calcium and bones

    MedlinePlus

    Bone strength and calcium ... or if your body does not absorb enough calcium, your bones can get weak or will not grow properly. ... injury. As you age, your body still needs calcium to keep your bones dense and strong. Most experts recommend at least ...

  18. Coronary artery calcium in hypertension: a review.

    PubMed

    Mallikethi-Reddy, Sagar; Rubenfire, Melvyn; Jackson, Lisa A; Brook, Robert D

    2015-12-01

    Coronary artery calcium (CAC) is a powerful independent predictor of future cardiovascular events. However, the clinical utility of calcium score testing specifically among patients with hypertension is not well defined. We performed a review of studies involving both high blood pressure (BP) and CAC to assess several aspects of the interrelationship. Among four specific topics evaluated, the main objective was to assess the independent association of CAC with cardiovascular risk among patients with hypertension. From 6822 identified publications, 21 studies met criteria for inclusion. All studies (n = 14) that reported the relationship between BP values and the presence or extent of coronary calcium found positive associations. The results from two studies linking coronary calcium with the risk for developing hypertension were mixed. Each of the five studies that evaluated the relationships between CAC score in regard to future cardiovascular events and/or all-cause mortality in patients with high BP reported independent positive associations. The inclusion of calcium score results into prediction models improved risk stratification when statistically evaluated. The findings of this review demonstrate that CAC testing is likely to be of clinical utility for tailoring the medical management of patients with high BP, particularly among individuals with mild or prehypertension. Future trials testing the clinical effectiveness of a calcium score-based treatment algorithm should be considered. PMID:26489731

  19. Calcium supplements: benefits and risks.

    PubMed

    Reid, I R; Bristow, S M; Bolland, M J

    2015-10-01

    Calcium is an essential element in the diet, but there is continuing controversy regarding its optimal intake, and its role in the pathogenesis of osteoporosis. Most studies show little evidence of a relationship between calcium intake and bone density, or the rate of bone loss. Re-analysis of data from the placebo group from the Auckland Calcium Study demonstrates no relationship between dietary calcium intake and rate of bone loss over 5 years in healthy older women with intakes varying from <400 to >1500 mg day(-1) . Thus, supplements are not needed within this range of intakes to compensate for a demonstrable dietary deficiency, but might be acting as weak anti-resorptive agents via effects on parathyroid hormone and calcitonin. Consistent with this, supplements do acutely reduce bone resorption and produce small short-term effects on bone density, without evidence of a cumulative density benefit. As a result, anti-fracture efficacy remains unproven, with no evidence to support hip fracture prevention (other than in a cohort with severe vitamin D deficiency) and total fracture numbers are reduced by 0-10%, depending on which meta-analysis is considered. Five recent large studies have failed to demonstrate fracture prevention in their primary analyses. This must be balanced against an increase in gastrointestinal side effects (including a doubling of hospital admissions for these problems), a 17% increase in renal calculi and a 20-40% increase in risk of myocardial infarction. Each of these adverse events alone neutralizes any possible benefit in fracture prevention. Thus, calcium supplements appear to have a negative risk-benefit effect, and so should not be used routinely in the prevention or treatment of osteoporosis. PMID:26174589

  20. Calcium bioavailability from calcium fortified food products.

    PubMed

    Kohls, K

    1991-08-01

    The calcium balance of 12 presumed healthy human young adult subjects was assessed. Subjects consumed a constant laboratory-controlled diet supplemented with one of four calcium-fortified food products: orange juice (OJ), milk (M), experimental pasteurized processed cheese (T), soda (S), or a calcium carbonate plus vitamin D tablet (CC). Study length was 6 weeks with seven-day experimental periods (2-days allowed for adjustment with 5-days combined for purposes of analysis). All urine and fecal samples were collected by the subjects for the duration of the study. Blood samples were drawn at the end of each experimental period. Urine and fecal calcium contents were determined. Blood samples were analyzed for alkaline phosphatase. Results of this study indicate a higher fecal calcium content (mg/day) when subjects consumed CC and T, and when subjects consumed self-selected diets, than when given S, M, or OJ. Urinary calcium excretion was significantly lower when subjects consumed OJ than when they consumed M, T, or their self-selected diets. A significantly larger positive calcium balance was demonstrated when subjects consumed OJ as compared to T. Fecal transmit time did not vary significantly. Serum alkaline phosphatase was significantly lower when subjects consumed T than when they consumed self-selected diets. PMID:1765836

  1. Foreshock patterns preceding large earthquakes in the subduction zone of Chile

    NASA Astrophysics Data System (ADS)

    Minadakis, George; Papadopoulos, Gerassimos A.

    2016-04-01

    Some of the largest earthquakes in the globe occur in the subduction zone of Chile. Therefore, it is of particular interest to investigate foreshock patterns preceding such earthquakes. Foreshocks in Chile were recognized as early as 1960. In fact, the giant (Mw9.5) earthquake of 22 May 1960, which was the largest ever instrumentally recorded, was preceded by 45 foreshocks in a time period of 33h before the mainshock, while 250 aftershocks were recorded in a 33h time period after the mainshock. Four foreshocks were bigger than magnitude 7.0, including a magnitude 7.9 on May 21 that caused severe damage in the Concepcion area. More recently, Brodsky and Lay (2014) and Bedford et al. (2015) reported on foreshock activity before the 1 April 2014 large earthquake (Mw8.2). However, 3-D foreshock patterns in space, time and size were not studied in depth so far. Since such studies require for good seismic catalogues to be available, we have investigated 3-D foreshock patterns only before the recent, very large mainshocks occurring on 27 February 2010 (Mw 8.8), 1 April 2014 (Mw8.2) and 16 September 2015 (Mw8.4). Although our analysis does not depend on a priori definition of short-term foreshocks, our interest focuses in the short-term time frame, that is in the last 5-6 months before the mainshock. The analysis of the 2014 event showed an excellent foreshock sequence consisting by an early-weak foreshock stage lasting for about 1.8 months and by a main-strong precursory foreshock stage that was evolved in the last 18 days before the mainshock. During the strong foreshock period the seismicity concentrated around the mainshock epicenter in a critical area of about 65 km mainly along the trench domain to the south of the mainshock epicenter. At the same time, the activity rate increased dramatically, the b-value dropped and the mean magnitude increased significantly, while the level of seismic energy released also increased. In view of these highly significant seismicity

  2. Calcium and calcium isotope changes during carbon cycle perturbations at the end-Permian

    NASA Astrophysics Data System (ADS)

    Komar, Nemanja; Zeebe, Richard

    2016-04-01

    Negative carbon and calcium isotope excursions, as well as climate shifts, took place during the most severe mass extinction event in Earth's history, the end-Permian (˜252 Ma). Investigating the connection between carbon and calcium cycles during transient carbon cycle perturbation events, such as the end-Permian, may help resolve the intricacies between the coupled calcium-carbon cycles, as well as provide a tool for constraining the causes of mass extinction. Here, we identify the deficiencies of a simplified calcium model employed in several previous studies and we demonstrate the importance of a fully coupled carbon-cycle model when investigating the dynamics of carbon and calcium cycling. Simulations with a modified version of the LOSCAR model, which includes a fully coupled carbon-calcium cycle, indicate that increased weathering rates and ocean acidification (potentially caused by Siberian Trap volcanism) are not capable of producing trends observed in the record, as previously claimed. Our model results suggest that combined effects of carbon input via Siberian Trap volcanism (12,000 Pg C), the cessation of biological carbon export, and variable calcium isotope fractionation (due to a change in the seawater carbonate ion concentration) represents a more plausible scenario. This scenario successfully reconciles δ13C and δ44Ca trends observed in the sediment record, as well as the proposed warming of >6oC.

  3. Calcium and calcium isotope changes during carbon cycle perturbations at the end-Permian

    NASA Astrophysics Data System (ADS)

    Komar, N.; Zeebe, R. E.

    2016-01-01

    Negative carbon and calcium isotope excursions, as well as climate shifts, took place during the most severe mass extinction event in Earth's history, the end-Permian (˜252 Ma). Investigating the connection between carbon and calcium cycles during transient carbon cycle perturbation events, such as the end-Permian, may help resolve the intricacies between the coupled calcium-carbon cycles, as well as provide a tool for constraining the causes of mass extinction. Here we identify the deficiencies of a simplified calcium model employed in several previous studies, and we demonstrate the importance of a fully coupled carbon cycle model when investigating the dynamics of carbon and calcium cycling. Simulations with a modified version of the Long-term Ocean-atmosphere-Sediment CArbon cycle Reservoir model, which includes a fully coupled carbon-calcium cycle, indicate that increased weathering rates and ocean acidification (potentially caused by Siberian Trap volcanism) are not capable of producing trends observed in the record, as previously claimed. Our model results suggest that combined effects of carbon input via Siberian Trap volcanism (12,000 Pg C), the cessation of biological carbon export, and variable calcium isotope fractionation (due to a change in the seawater carbonate ion concentration) represents a more plausible scenario. This scenario successfully reconciles δ13C and δ44Ca trends observed in the sediment record, as well as the proposed warming of >6°C.

  4. Live Imaging of Calcium Dynamics during Axon Degeneration Reveals Two Functionally Distinct Phases of Calcium Influx

    PubMed Central

    Yamagishi, Yuya; Tessier-Lavigne, Marc

    2015-01-01

    Calcium is a key regulator of axon degeneration caused by trauma and disease, but its specific spatial and temporal dynamics in injured axons remain unclear. To clarify the function of calcium in axon degeneration, we observed calcium dynamics in single injured neurons in live zebrafish larvae and tested the temporal requirement for calcium in zebrafish neurons and cultured mouse DRG neurons. Using laser axotomy to induce Wallerian degeneration (WD) in zebrafish peripheral sensory axons, we monitored calcium dynamics from injury to fragmentation, revealing two stereotyped phases of axonal calcium influx. First, axotomy triggered a transient local calcium wave originating at the injury site. This initial calcium wave only disrupted mitochondria near the injury site and was not altered by expression of the protective WD slow (WldS) protein. Inducing multiple waves with additional axotomies did not change the kinetics of degeneration. In contrast, a second phase of calcium influx occurring minutes before fragmentation spread as a wave throughout the axon, entered mitochondria, and was abolished by WldS expression. In live zebrafish, chelating calcium after the first wave, but before the second wave, delayed the progress of fragmentation. In cultured DRG neurons, chelating calcium early in the process of WD did not alter degeneration, but chelating calcium late in WD delayed fragmentation. We propose that a terminal calcium wave is a key instructive component of the axon degeneration program. SIGNIFICANCE STATEMENT Axon degeneration resulting from trauma or neurodegenerative disease can cause devastating deficits in neural function. Understanding the molecular and cellular events that execute axon degeneration is essential for developing treatments to address these conditions. Calcium is known to contribute to axon degeneration, but its temporal requirements in this process have been unclear. Live calcium imaging in severed zebrafish neurons and temporally controlled

  5. APOE polymorphisms influence longitudinal lipid trends preceding intracerebral hemorrhage

    PubMed Central

    Phuah, Chia-Ling; Raffeld, Miriam R.; Ayres, Alison M.; Gurol, M. Edip; Viswanathan, Anand; Greenberg, Steven M.; Biffi, Alessandro; Rosand, Jonathan

    2016-01-01

    Objective: We sought to determine whether APOE genotype influences a previously observed decline in serum total cholesterol (TC) and low-density lipoprotein (LDL) levels preceding primary intracerebral hemorrhage (ICH), as a potential demonstration of nonamyloid mechanisms of APOE in ICH risk. Methods: We performed a single-center retrospective longitudinal analysis using patients with known APOE genotype drawn from an ongoing cohort study of ICH. Serum lipid measurements for TC, triglycerides (TGs), LDL, and high-density lipoprotein (HDL) collected within 2 years before and after index ICH were extracted from electronic medical records. Piecewise linear mixed-effects models were used to compare APOE allele–specific effects on temporal serum lipid trends in ICH. Demographics, medical history, medications, and health maintenance data were included as fixed effects. Inter- and intraindividual variations in lipid levels were modeled as random effects. Results: A total of 124 ICH cases were analyzed. APOE ε4 carriers had greater rates of decline in serum TC and LDL within 6 months preceding ICH (TC: −7.30 mg/dL/mo, p = 0.0035; LDL: −8.44 mg/dL/mo, p = 0.0001). Conversely, serum TC and LDL levels in APOE ε2 carriers were unchanged within the same time period. APOE genotype had no associations with serum HDL or TG trends. Conclusions: APOE allele status predicts serum TC and LDL changes preceding acute ICH. Our results have implications for ongoing efforts in dissecting the role of dyslipidemia in cerebrovascular disease risk. APOE genotype–specific influence on lipid trends provides a clue for one mechanism by which APOE may influence risk of ICH. Further characterization of the metabolic roles of APOE is needed to improve the understanding of APOE biology in cerebrovascular disease risk. PMID:27433544

  6. Precedence based speech segregation in bilateral cochlear implant users

    PubMed Central

    Hossain, Shaikat; Montazeri, Vahid; Assmann, Peter F.; Litovsky, Ruth Y.

    2015-01-01

    The precedence effect (PE) enables the perceptual dominance by a source (lead) over an echo (lag) in reverberant environments. In addition to facilitating sound localization, the PE can play an important role in spatial unmasking of speech. Listeners attending to binaural vocoder simulations with identical channel center frequencies and phase demonstrated PE-based benefits in a closed-set speech segregation task. When presented with the same stimuli, bilateral cochlear implant users did not derive such benefits. These findings suggest that envelope extraction in itself may not lead to a breakdown of the PE benefits, and that other factors may play a role. PMID:26723365

  7. Precedence based speech segregation in bilateral cochlear implant users.

    PubMed

    Hossain, Shaikat; Montazeri, Vahid; Assmann, Peter F; Litovsky, Ruth Y

    2015-12-01

    The precedence effect (PE) enables the perceptual dominance by a source (lead) over an echo (lag) in reverberant environments. In addition to facilitating sound localization, the PE can play an important role in spatial unmasking of speech. Listeners attending to binaural vocoder simulations with identical channel center frequencies and phase demonstrated PE-based benefits in a closed-set speech segregation task. When presented with the same stimuli, bilateral cochlear implant users did not derive such benefits. These findings suggest that envelope extraction in itself may not lead to a breakdown of the PE benefits, and that other factors may play a role. PMID:26723365

  8. Augmented force output in skeletal muscle fibres of Xenopus following a preceding bout of activity.

    PubMed Central

    Bruton, J D; Westerblad, H; Katz, A; Lännergren, J

    1996-01-01

    1. The effect of a brief period of activity on subsequent isometric tetanic force production was investigated in single muscle fibres of Xenopus laevis. 2. Following a train of ten tetani separated by 4 s intervals, tetanic force was significantly augmented by about 10%. The tetanic force augmentation persisted for at least 15 min and then slowly subsided. A similar potentiation was seen following trains of five and twenty tetani. 3. During the period of tetanic force potentiation, tetanic calcium was reduced by more than 30%, and intracellular pH was reduced from 7.15 +/- 0.07 to 7.03 +/- 0.11 (n = 4). 4. Fibre swelling was greatest at 1 min and then subsided over 15-20 min and possibly accounted for a small part of the observed force potentiation. 5. A reduction in the inorganic phosphate (P1) concentration of more than 40% was found in fibres frozen in liquid nitrogen at the peak of force potentiation compared with resting fibres. 6. It is concluded that the augmentation of tetanic force found after a brief preceding bout of activity is due to a reduction in inorganic phosphate. This mechanism may underlie the improved performance observed in athletes after warm-up. Images Figure 2 PMID:8735706

  9. The tailings dam failure of 5 November 2015 in SE Brazil and its preceding seismic sequence

    NASA Astrophysics Data System (ADS)

    Agurto-Detzel, H.; Bianchi, M.; Assumpção, M.; Schimmel, M.; Collaço, B.; Ciardelli, C.; Barbosa, J. R.; Calhau, J.

    2016-05-01

    The collapse of a mine tailings dam and subsequent flood in SE Brazil on 5 November 2015 was preceded by a small-magnitude seismic sequence. In this report, we explore the spatiotemporal associations between the seismic events and the accident and discuss their possible connection. We also analyze the signals generated by the turbulent mudflow, as recorded by the Brazilian Seismographic Network (RSBR). In light of our observations, we propose as possible contributing factor for the dam collapse either ground shaking and/or soil liquefaction triggered by the earthquakes. The possibility of such a small-magnitude earthquake contributing to the collapse of a tailings dam raises important concerns regarding safety and related legislation of dams in Brazil and the world.

  10. Multiple Skeletal Muscle Metastases from Colon Carcinoma Preceded by Paraneoplastic Dermatomyositis

    PubMed Central

    Gerardi, Assunta Maria Teresa; Fersini, Alberto; Modoni, Sergio; Stoppino, Luca Pio; Sanguedolce, Francesca; Bufo, Pantaleo; Neri, Vincenzo

    2013-01-01

    Skeletal muscle metastases are very rare events in colorectal carcinoma. By contrast, dermatomyositis is an idiopathic inflammatory myopathy with characteristic cutaneous manifestations and a well-recognized association with several human malignancies and, among others, colorectal cancer. Here, we report the case of a 71-year-old woman with paraneoplastic dermatomyositis followed by the development of a metastatic colon cancer. Interestingly, this patient developed multiple skeletal metastases which were preceded by the worsening of systemic symptoms of dermatomyositis. This observation suggests that, while muscle tissue is usually resistant to the development of tumor metastases, the inflammatory and immune response which characterizes and boosts paraneoplastic myopathy may represent a favorable soil for tumor cell invasion and metastasization to skeletal muscles. PMID:23983709

  11. Multiple skeletal muscle metastases from colon carcinoma preceded by paraneoplastic dermatomyositis.

    PubMed

    Landriscina, Matteo; Gerardi, Assunta Maria Teresa; Fersini, Alberto; Modoni, Sergio; Stoppino, Luca Pio; Macarini, Luca; Sanguedolce, Francesca; Bufo, Pantaleo; Neri, Vincenzo

    2013-01-01

    Skeletal muscle metastases are very rare events in colorectal carcinoma. By contrast, dermatomyositis is an idiopathic inflammatory myopathy with characteristic cutaneous manifestations and a well-recognized association with several human malignancies and, among others, colorectal cancer. Here, we report the case of a 71-year-old woman with paraneoplastic dermatomyositis followed by the development of a metastatic colon cancer. Interestingly, this patient developed multiple skeletal metastases which were preceded by the worsening of systemic symptoms of dermatomyositis. This observation suggests that, while muscle tissue is usually resistant to the development of tumor metastases, the inflammatory and immune response which characterizes and boosts paraneoplastic myopathy may represent a favorable soil for tumor cell invasion and metastasization to skeletal muscles. PMID:23983709

  12. Possible deep fault slip preceding the 2004 Parkfield earthquake, inferred from detailed observations of tectonic tremor

    USGS Publications Warehouse

    Shelly, D.R.

    2009-01-01

    Earthquake predictability depends, in part, on the degree to which sudden slip is preceded by slow aseismic slip. Recently, observations of deep tremor have enabled inferences of deep slow slip even when detection by other means is not possible, but these data are limited to certain areas and mostly the last decade. The region near Parkfield, California, provides a unique convergence of several years of high-quality tremor data bracketing a moderate earthquake, the 2004 magnitude 6.0 event. Here, I present detailed observations of tectonic tremor from mid-2001 through 2008 that indicate deep fault slip both before and after the Parkfield earthquake that cannot be detected with surface geodetic instruments. While there is no obvious short-term precursor, I find unidirectional tremor migration accompanied by elevated tremor rates in the 3 months prior to the earthquake, which suggests accelerated creep on the fault ???16 km beneath the eventual earthquake hypocenter. Copyright 2009 by the American Geophysical Union.

  13. Effect of preceding speech on nonspeech sound perception

    NASA Astrophysics Data System (ADS)

    Stephens, Joseph D.; Holt, Lori L.

    2002-05-01

    Data from Japanese quail suggest that the effect of preceding liquids (/l/ or /r/) on response to subsequent stops (/g/ or /d/) arises from general auditory processes sensitive to the spectral structure of sound [A. J. Lotto, K. R. Kluender, and L. L. Holt, J. Acoust. Soc. Am. 102, 1134-1140 (1997)]. If spectral content is key, appropriate nonspeech sounds should influence perception of speech sounds and vice versa. The former effect has been demonstrated [A. J. Lotto and K. R. Kluender, Percept. Psychophys. 60, 602-619 (1998)]. The current experiment investigated the influence of speech on the perception of nonspeech sounds. Nonspeech stimuli were 80-ms chirps modeled after the F2 and F3 transitions in /ga/ and /da/. F3 onset was increased in equal steps from 1800 Hz (/ga/ analog) to 2700 Hz (/da/ analog) to create a ten-member series. During AX discrimination trials, listeners heard chirps that were three steps apart on the series. Each chirp was preceded by a synthesized /al/ or /ar/. Results showed context effects predicted from differences in spectral content between the syllables and chirps. These results are consistent with the hypothesis that spectral contrast influences context effects in speech perception. [Work supported by ONR, NOHR, and CNBC.

  14. Expectations from preceding prosody influence segmentation in online sentence processing

    PubMed Central

    Brown, Meredith; Salverda, Anne Pier; Dilley, Laura C.; Tanenhaus, Michael K.

    2013-01-01

    Previous work examining prosodic cues in online spoken-word recognition has focused primarily on local cues to word identity. However, recent studies have suggested that utterance-level prosodic patterns can also influence the interpretation of subsequent sequences of lexically ambiguous syllables (Dilley, Mattys, & Vinke, Journal of Memory and Language, 63:274–294, 2010; Dilley & McAuley, Journal of Memory and Language, 59:294–311, 2008). To test the hypothesis that these distal prosody effects are based on expectations about the organization of upcoming material, we conducted a visual-world experiment. We examined fixations to competing alternatives such as pan and panda upon hearing the target word panda in utterances in which the acoustic properties of the preceding sentence material had been manipulated. The proportions of fixations to the monosyllabic competitor were higher beginning 200 ms after target word onset when the preceding prosody supported a prosodic constituent boundary following pan-, rather than following panda. These findings support the hypothesis that expectations based on perceived prosodic patterns in the distal context influence lexical segmentation and word recognition. PMID:21968925

  15. Pronounced kidney hypoxia precedes albuminuria in type 1 diabetic mice.

    PubMed

    Franzén, Stephanie; Pihl, Liselotte; Khan, Nadeem; Gustafsson, Håkan; Palm, Fredrik

    2016-05-01

    Intrarenal tissue hypoxia has been proposed as a unifying mechanism for the development of chronic kidney disease, including diabetic nephropathy. However, hypoxia has to be present before the onset of kidney disease to be the causal mechanism. To establish whether hypoxia precedes the onset of diabetic nephropathy, we implemented a minimally invasive electron paramagnetic resonance oximetry technique using implanted oxygen sensing probes for repetitive measurements of in vivo kidney tissue oxygen tensions in mice. Kidney cortex oxygen tensions were measured before and up to 15 days after the induction of insulinopenic diabetes in male mice and compared with normoglycemic controls. On day 16, urinary albumin excretions and conscious glomerular filtration rates were determined to define the temporal relationship between intrarenal hypoxia and disease development. Diabetic mice developed pronounced intrarenal hypoxia 3 days after the induction of diabetes, which persisted throughout the study period. On day 16, diabetic mice had glomerular hyperfiltration, but normal urinary albumin excretion. In conclusion, intrarenal tissue hypoxia in diabetes precedes albuminuria thereby being a plausible cause for the onset and progression of diabetic nephropathy. PMID:26936871

  16. Does lumbar facet arthrosis precede disc degeneration? A postmortem study.

    PubMed

    Eubanks, Jason David; Lee, Michael J; Cassinelli, Ezequiel; Ahn, Nicholas U

    2007-11-01

    It is believed lumbar degeneration begins in the disc, where desiccation and collapse lead to instability and compensatory facet arthrosis. We explored the contrary contention that facet degeneration precedes disc degeneration by examining 647 skeletal lumbar spines. Using facet osteophytosis as a measure of facet degeneration and vertebral rim osteophytosis as a measure of disc degeneration, we assumed bone degeneration in both locations equally reflected the progression of those in the soft tissues. We graded arthrosis Grade 0 to 4 on a continuum from no arthritis to ankylosis. The data were analyzed for different age groups to examine patterns of degeneration with age. Specimens younger than 30 years of age had a higher prevalence of facet osteophytosis compared with vertebral rim osteophotosis at L1-L2 and L2-L3. Specimens aged 30 to 39 years showed more facet osteophytosis than vertebral rim osteophytosis at L4-L5. Specimens older than 40 years, however, showed more vertebral rim osteophytosis compared with facet osteophytosis at all levels except L4-L5 and L5-S1. This skeletal study suggests facet osteophytosis appears early in the degenerative process, preceding vertebral rim osteophytosis of degenerating intervertebral discs. However, once facets begin deteriorating with age, vertebral rim osteophytosis overtakes continued facet osteophytosis. These data challenge the belief that facet osteophytosis follows vertebral rim osteophytosis; rather, it appears vertebral rim osteophytosis progresses more rapidly in later years, but facet osteophotosis occurs early, predominating in younger individuals. PMID:17767079

  17. Diastolic dysfunction precedes hypoxia-induced mortality in dystrophic mice

    PubMed Central

    Townsend, DeWayne

    2015-01-01

    Duchenne muscular dystrophy (DMD) is a progressive striated muscle disease that is characterized by skeletal muscle weakness with progressive respiratory and cardiac failure. Together respiratory and cardiac disease account for the majority of mortality in the DMD patient population. However, little is known regarding the effects of respiratory dysfunction on the dystrophic heart. The studies described here examine the effects of acute hypoxia on cardiac function. These studies demonstrate, for the first time, that a mouse model of DMD displays significant mortality following acute exposure to hypoxia. This mortality is characterized by a steady decline in systolic function. Retrospective analysis reveals that significant decreases in diastolic dysfunction, especially in the right ventricle, precede the decline in systolic pressure. The initial hemodynamic response to acute hypoxia in the mouse is similar to that observed in larger species, with significant increases in right ventricular afterload and decreases in left ventricular preload being observed. Significant increases in heart rate and contractility suggest hypoxia-induced activation of the sympathetic nervous system. These studies provide evidence that while hypoxia presents significant hemodynamic challenges to the dystrophic right ventricle, global cardiac dysfunction precedes hypoxia-induced mortality in the dystrophic heart. These findings are clinically relevant as the respiratory insufficiency evident in patients with DMD results in significant bouts of hypoxia. The results of these studies indicate that hypoxia may contribute to the acceleration of the heart disease in DMD patients. Importantly, hypoxia can be avoided through the use of ventilatory support. PMID:26311833

  18. Selective attention in the honeybee optic lobes precedes behavioral choices

    PubMed Central

    Paulk, Angelique C.; Stacey, Jacqueline A.; Pearson, Thomas W. J.; Taylor, Gavin J.; Moore, Richard J. D.; Srinivasan, Mandyam V.; van Swinderen, Bruno

    2014-01-01

    Attention allows animals to respond selectively to competing stimuli, enabling some stimuli to evoke a behavioral response while others are ignored. How the brain does this remains mysterious, although it is increasingly evident that even animals with the smallest brains display this capacity. For example, insects respond selectively to salient visual stimuli, but it is unknown where such selectivity occurs in the insect brain, or whether neural correlates of attention might predict the visual choices made by an insect. Here, we investigate neural correlates of visual attention in behaving honeybees (Apis mellifera). Using a closed-loop paradigm that allows tethered, walking bees to actively control visual objects in a virtual reality arena, we show that behavioral fixation increases neuronal responses to flickering, frequency-tagged stimuli. Attention-like effects were reduced in the optic lobes during replay of the same visual sequences, when bees were not able to control the visual displays. When bees were presented with competing frequency-tagged visual stimuli, selectivity in the medulla (an optic ganglion) preceded behavioral selection of a stimulus, suggesting that modulation of early visual processing centers precedes eventual behavioral choices made by these insects. PMID:24639490

  19. Calcium intake is not associated with increased coronary artery calcification: The Framingham Study

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Adequate calcium intake is known to protect the skeleton. However, studies that have reported adverse effects of calcium supplementation on vascular events have raised widespread concern. We assessed the association between calcium intake (from diet and supplements) and coronary artery calcification...

  20. Cellular Mechanisms of Calcium-Mediated Triggered Activity

    NASA Astrophysics Data System (ADS)

    Song, Zhen

    proteins. How those various factors interact synergistically to promote DADs is not well understood. Furthermore, at an even more basic level, it remains unclear to what degree spontaneous Ca2+ release and the appearance of DADs are deterministic, meaning reproducible under identical conditions, or inherently stochastic like nucleation in the physical context of phase transitions. In this thesis, we use and further develop a biologically detailed computational model to investigate basic aspects of TA in isolated heart cells (cardiac myocytes). Isolated cells can be obtained by enzymatic dissociation of heart tissue and studied experimentally using standard electrophysiological recording methods and confocal imaging of Ca2+ dynamics. Hence they provide a well controlled setting to investigate the generation of DADs under well controlled conditions. Our computational model captures essential aspects of the hierarchical architecture of ventricular myocytes, which consists of a large number of approximately 20,000 to 50,000 regularly spaced submicron regions containing clusters of 50-100 Ryanodine receptor (RyR) Ca2+ release channels. Each of those regions acts as a discrete "calcium release unit'' (CRU). Therefore our model allows us to address for the first time quantitatively the fundamental question of whether Ca2+ release, which is highly stochastic at the level of a single calcium release unit, is stochastic or deterministic at the whole cell level where the Ca 2+ signal is the summation of releases from a large number of units. Addressing this question is the focus of the first part of this thesis. Our results demonstrate that both the initiation and termination of TA are highly stochastic at the whole cell level due to the spatiotemporal organization of discrete release events into multiple Ca2+ waves. Our results allow us to characterize the probability distributions that govern the number of DADs preceding a triggered action potential and the number of triggered

  1. Changes in autonomic activity preceding onset of nonsustained ventricular tachycardia

    NASA Technical Reports Server (NTRS)

    Osaka, M.; Saitoh, H.; Sasabe, N.; Atarashi, H.; Katoh, T.; Hayakawa, H.; Cohen, R. J.

    1996-01-01

    Background: The triggering role of the autonomic nervous system in the initiation of ventricular tachycardia has not been established. To investigate the relationship between changes in autonomic activity and the occurrence of nonsustained ventricular tachycardia (NSVT) we examined heart rate variability (HRV) during the 2-hour period preceding spontaneous episodes of NSVT. Twenty-four subjects were identified retrospectively as having had one episode of NSVT during 24-hour Holter ECC recording. Methods: We measured the mean interval between normal heats (meanRR), the standard deviation of the intervals between beats (SD), the percentage of counts of sequential intervals between normal beats with a change of >50 ms (%RR50), the logarithms of low- and high-frequency spectral components (lnLF, lnHF) of HRV for sequential 10-minute segments preceding NSVT. The correlation dimension (CDim) of HRV was calculated similarly for sequential 20-minute segments. We assessed the significance of the time-course change of each marker over the 120-minute period prior to NSVT onset. Results: MeanRR (P < 0.05), lnLF (P < 0.0001), lnHF (P < 0.0001), the natural logarithm of the ratio of LF to HF (ln[LF/HF]; P < 0.05), and CDim (P < 0.05) showed significant time-course changes during that period, while SD and %RR50 did not. MeanRR, lnLF, lnHF, and CDim all decreased prior to the onset of NSVT, whereas ln(LF/HF) increased. We divided the subjects into two groups: one consisting of 12 patients with coronary artery disease; and the second group of 12 patients without known coronary artery disease. Both groups showed significant changes (P < 0.05) of CDim, lnLF, and lnHF preceding the episodes of NSVT. Conclusions: Changes in the pattern of HRV prior to the onset of episodes of NSVT suggest that changes in autonomic activity may commonly play a role in the triggering of spontaneous episodes of NSVT in susceptible patients. The measured changes suggest a reduction in parasympathetic

  2. Extracellular calcium sensing and extracellular calcium signaling

    NASA Technical Reports Server (NTRS)

    Brown, E. M.; MacLeod, R. J.; O'Malley, B. W. (Principal Investigator)

    2001-01-01

    , localized changes in Ca(o)(2+) within the ECF can originate from several mechanisms, including fluxes of calcium ions into or out of cellular or extracellular stores or across epithelium that absorb or secrete Ca(2+). In any event, the CaR and other receptors/sensors for Ca(o)(2+) and probably for other extracellular ions represent versatile regulators of numerous cellular functions and may serve as important therapeutic targets.

  3. Decision Preceding Negativity in the Iowa Gambling Task: An ERP study

    ERIC Educational Resources Information Center

    Bianchin, Marta; Angrilli, Alessandro

    2011-01-01

    The present study aimed to investigate the slow negative potential (termed Decision Preceding Negativity, DPN, from the family of the Readiness Potential) which precedes a willed risky decision. To this end, evoked potentials preceding and following an economic choice were measured in a sample of 16 male students during the Iowa Gambling Task…

  4. 22 CFR 42.68 - Informal evaluation of family members if principal applicant precedes them.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... principal applicant precedes them. 42.68 Section 42.68 Foreign Relations DEPARTMENT OF STATE VISAS VISAS... Visas § 42.68 Informal evaluation of family members if principal applicant precedes them. (a) Preliminary determination of visa eligibility. If a principal applicant proposes to precede the family to...

  5. 22 CFR 42.68 - Informal evaluation of family members if principal applicant precedes them.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... principal applicant precedes them. 42.68 Section 42.68 Foreign Relations DEPARTMENT OF STATE VISAS VISAS... Visas § 42.68 Informal evaluation of family members if principal applicant precedes them. (a) Preliminary determination of visa eligibility. If a principal applicant proposes to precede the family to...

  6. 22 CFR 42.68 - Informal evaluation of family members if principal applicant precedes them.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... principal applicant precedes them. 42.68 Section 42.68 Foreign Relations DEPARTMENT OF STATE VISAS VISAS... Visas § 42.68 Informal evaluation of family members if principal applicant precedes them. (a) Preliminary determination of visa eligibility. If a principal applicant proposes to precede the family to...

  7. 22 CFR 42.68 - Informal evaluation of family members if principal applicant precedes them.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... principal applicant precedes them. 42.68 Section 42.68 Foreign Relations DEPARTMENT OF STATE VISAS VISAS... Visas § 42.68 Informal evaluation of family members if principal applicant precedes them. (a) Preliminary determination of visa eligibility. If a principal applicant proposes to precede the family to...

  8. 22 CFR 42.68 - Informal evaluation of family members if principal applicant precedes them.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... principal applicant precedes them. 42.68 Section 42.68 Foreign Relations DEPARTMENT OF STATE VISAS VISAS... Visas § 42.68 Informal evaluation of family members if principal applicant precedes them. (a) Preliminary determination of visa eligibility. If a principal applicant proposes to precede the family to...

  9. Calcium and egg activation in Drosophila.

    PubMed

    Sartain, Caroline V; Wolfner, Mariana F

    2013-01-01

    In many animals, a rise in intracellular calcium levels is the trigger for egg activation, the process by which an arrested mature oocyte transitions to prepare for embryogenesis. In nearly all animals studied to date, this calcium rise, and thus egg activation, is triggered by the fertilizing sperm. However in the insects that have been examined, fertilization is not necessary to activate their oocytes. Rather, these insects' eggs activate as they transit through the female's reproductive tract, regardless of male contribution. Recent studies in Drosophila have shown that egg activation nevertheless requires calcium and that the downstream events and molecules of egg activation are also conserved, despite the difference in initial trigger. Genetic studies have uncovered essential roles for the calcium-dependent enzyme calcineurin and its regulator calcipressin, and have hinted at roles for calmodulin, in Drosophila egg activation. Physiological and in vitro studies have led to a model in which mechanical forces that impact the Drosophila oocyte as it moves through the reproductive tract triggers the influx of calcium from the external environment, thereby initiating egg activation. Future research will aim to test this model, as well as to determine the spatiotemporal dynamics of cytoplasmic calcium flux and mode of signal propagation in this unique system. PMID:23218670

  10. Direct Imaging of Hippocampal Epileptiform Calcium Motifs Following Kainic Acid Administration in Freely Behaving Mice

    PubMed Central

    Berdyyeva, Tamara K.; Frady, E. Paxon; Nassi, Jonathan J.; Aluisio, Leah; Cherkas, Yauheniya; Otte, Stephani; Wyatt, Ryan M.; Dugovic, Christine; Ghosh, Kunal K.; Schnitzer, Mark J.; Lovenberg, Timothy; Bonaventure, Pascal

    2016-01-01

    Prolonged exposure to abnormally high calcium concentrations is thought to be a core mechanism underlying hippocampal damage in epileptic patients; however, no prior study has characterized calcium activity during seizures in the live, intact hippocampus. We have directly investigated this possibility by combining whole-brain electroencephalographic (EEG) measurements with microendoscopic calcium imaging of pyramidal cells in the CA1 hippocampal region of freely behaving mice treated with the pro-convulsant kainic acid (KA). We observed that KA administration led to systematic patterns of epileptiform calcium activity: a series of large-scale, intensifying flashes of increased calcium fluorescence concurrent with a cluster of low-amplitude EEG waveforms. This was accompanied by a steady increase in cellular calcium levels (>5 fold increase relative to the baseline), followed by an intense spreading calcium wave characterized by a 218% increase in global mean intensity of calcium fluorescence (n = 8, range [114–349%], p < 10−4; t-test). The wave had no consistent EEG phenotype and occurred before the onset of motor convulsions. Similar changes in calcium activity were also observed in animals treated with 2 different proconvulsant agents, N-methyl-D-aspartate (NMDA) and pentylenetetrazol (PTZ), suggesting the measured changes in calcium dynamics are a signature of seizure activity rather than a KA-specific pathology. Additionally, despite reducing the behavioral severity of KA-induced seizures, the anticonvulsant drug valproate (VA, 300 mg/kg) did not modify the observed abnormalities in calcium dynamics. These results confirm the presence of pathological calcium activity preceding convulsive motor seizures and support calcium as a candidate signaling molecule in a pathway connecting seizures to subsequent cellular damage. Integrating in vivo calcium imaging with traditional assessment of seizures could potentially increase translatability of pharmacological

  11. Constraints on just enough inflation preceded by a thermal era

    NASA Astrophysics Data System (ADS)

    Das, Suratna; Goswami, Gaurav; Prasad, Jayanti; Rangarajan, Raghavan

    2016-01-01

    If the inflationary era is preceded by a radiation-dominated era in which the inflaton too was in thermal equilibrium at some very early time, then the CMB data places an upper bound on the comoving temperature of the (decoupled) inflaton quanta. In addition, if one considers models of "just enough" inflation, where the number of e-foldings of inflation is just enough to solve the horizon and flatness problems, then we get a lower bound on the Hubble parameter during inflation, Hinf, which is in severe conflict with the upper bound from tensor perturbations. Alternatively, imposing the upper bound on Hinf implies that such scenarios are compatible with the data only if the number of relativistic degrees of freedom in the thermal bath in the preinflationary Universe is extremely large (greater than 109 or 1011 ). We are not aware of scenarios in which this can be satisfied.

  12. The physics of charge separation preceding lightning strokes in thunderclouds

    NASA Technical Reports Server (NTRS)

    Kyrala, Ali

    1987-01-01

    The physics of charge separation preceding lightning strokes in thunderclouds is presented by three types of arguments: An explanation is given for the aggregation of electrical charges of like sign overcoming Coulomb repulsion by attraction due to exchange interaction. The latter is well known in quantum mechanics from the theories of the nuclear bond and the covalent bond. A classical electrostatic model of charge balls of segregated positive and negative charges in the thundercloud is presented. These charge balls can only be maintained in temporarily stable locations by a containing vortex. Because they will be of different sizes and masses, they will stabilize at different altitudes when drag forces are included with the given electrostatic force. The question of how the charges become concentrated again after lightning discharges is approached by means of the collisional Boltzmann transport equation to explain quasi-periodic recharging. It is shown that solutions cannot be separable in both position and time if they are to represent aggregation.

  13. [The influences of laterality on global precedence: interference effects].

    PubMed

    Kimura, Jun

    2008-02-01

    This study aimed to clarify the influence of laterality on interference effects for global precedence, and to examine the mechanism of these effects. In most previous studies, the neutral condition was excluded from the consistency factor and the difference of latencies between the consistent and inconsistent conditions was regarded as the interference score, which may not be accurate. In this study, the difference of latencies between the neutral and the inconsistent condition was regarded as the interference score. The results of the analysis of variance (ANOVA) for latencies showed that interference effects influenced only right visual field-left hemisphere (RVF-LH), and facilitation effects influenced only left visual field-right hemisphere (LVF-RH) in the local condition. These findings indicate that it does not matter how optimal processing influenced interference effects on suboptimal processing in each hemisphere, for example how global processing influenced local processing in the right hemisphere, but rather how each hemisphere controlled optimal processing. PMID:18402064

  14. Stepped-to-dart leaders preceding lightning return strokes

    NASA Astrophysics Data System (ADS)

    Stolzenburg, Maribeth; Marshall, Thomas C.; Karunarathne, Sumedhe; Karunarathna, Nadeeka; Warner, Tom A.; Orville, Richard E.

    2013-09-01

    time-correlated high-speed video and electric field change data, three cases are described in which dart leaders toward ground are immediately preceded by stepped leaders that find and use previously used channels. These "stepped-to-dart leaders" occur in three natural negative ground flashes. Prior to the stepped-to-dart connection, the leaders have characteristics of stepped leaders, including average two-dimensional speeds of 1.6-2.7 × 105 m s-1 (visible from 5.5, 3.4, and 0.9 km altitude). After the connection, they behave as dart (or dart-stepped) leaders, with larger amplitude E-change pulses and faster average speeds of 3.4-7.8 × 106 m s-1. Connection altitudes are 3.32, 1.57, and 0.75 km. Immediately after the connection, there is a brief lighting in a short part of the prior return stroke channel. Luminosity travels up the stepped leader path after the connection, while the dart leader proceeds toward ground. In two cases, all the strokes subsequent to the stepped-to-dart stroke follow the visible portion of its channel. The other case has two subsequent strokes which do not reuse any portion of the stepped-to-dart channel. For the other 12 strokes in these flashes, stepped leader average speeds range from 1.7 to 3.0 × 105 m s-1, and dart leader average speeds are 0.82 to 16.67 × 106 m s-1. Overall, the return stroke waveforms give reasonable indication of the type of leader that preceded the stroke. Stepped-to-dart leaders are apparently rare in optical data, occurring in about 1% of subsequent strokes and 2.5% of flashes.

  15. An overview of techniques for the measurement of calcium distribution, calcium fluxes, and cytosolic free calcium in mammalian cells.

    PubMed Central

    Borle, A B

    1990-01-01

    An array of techniques can be used to study cell calcium metabolism that comprises several calcium compartments and many types of transport systems such as ion channels, ATP-dependent pumps, and antiporters. The measurement of total cell calcium brings little information of value since 60 to 80% of total cell calcium is actually bound to the extracellular glycocalyx. Cell fractionation and differential centrifugation have been used to study intracellular Ca2+ compartmentalization, but the methods suffer from the possibility of Ca2+ loss or redistribution among cell fractions. Steady-state kinetic analyses of 45Ca uptake or desaturation curves have been used to study the distribution of Ca2+ among various kinetic pools in living cells and their rate of Ca2+ exchange, but the analyses are constrained by many limitations. Nonsteady-state tracer studies can provide information about rapid changes in calcium influx or efflux in and out of the cell. Zero-time kinetics of 45Ca uptake can detect instantaneous changes in calcium influx, while 45Ca fractional efflux ratio, can detect rapid stimulations or inhibitions of calcium efflux out of cells. Permeabilized cells have been successfully used to gauge the relative role of intracellular organelles in controlling [Ca2+]i. The measurement of the cytosolic ionized calcium ([Ca2+]i) is undoubtedly the most important and, physiologically, the most relevant method available. The choice of the appropriate calcium indicator, fluorescent, bioluminescent, metallochromic, or Ca2(+)-sensitive microelectrodes depends on the cell type and the magnitude and time constant of the event under study. Each probe has specific assets and drawbacks. The study of plasma membrane vesicles derived from baso-lateral or apical plasmalemma can also bring important information on the (Ca2(+)-Mg2+) ATPase-dependent calcium pump and on the kinetics and stoichiometry of the Na(+)-Ca2+ antiporter. The best strategy to study cell calcium metabolism is to

  16. Simulation strategies for calcium microdomains and calcium-regulated calcium channels.

    PubMed

    von Wegner, Frederic; Wieder, Nicolas; Fink, Rainer H A

    2012-01-01

    In this article, we present an overview of simulation strategies in the context of subcellular domains where calcium-dependent signaling plays an important role. The presentation follows the spatial and temporal scales involved and represented by each algorithm. As an exemplary cell type, we will mainly cite work done on striated muscle cells, i.e. skeletal and cardiac muscle. For these cells, a wealth of ultrastructural, biophysical and electrophysiological data is at hand. Moreover, these cells also express ubiquitous signaling pathways as they are found in many other cell types and thus, the generalization of the methods and results presented here is straightforward.The models considered comprise the basic calcium signaling machinery as found in most excitable cell types including Ca(2+) ions, diffusible and stationary buffer systems, and calcium regulated calcium release channels. Simulation strategies can be differentiated in stochastic and deterministic algorithms. Historically, deterministic approaches based on the macroscopic reaction rate equations were the first models considered. As experimental methods elucidated highly localized Ca(2+) signaling events occurring in femtoliter volumes, stochastic methods were increasingly considered. However, detailed simulations of single molecule trajectories are rarely performed as the computational cost implied is too large. On the mesoscopic level, Gillespie's algorithm is extensively used in the systems biology community and with increasing frequency also in models of microdomain calcium signaling. To increase computational speed, fast approximations were derived from Gillespie's exact algorithm, most notably the chemical Langevin equation and the τ-leap algorithm. Finally, in order to integrate deterministic and stochastic effects in multiscale simulations, hybrid algorithms are increasingly used. These include stochastic models of ion channels combined with deterministic descriptions of the calcium buffering

  17. Air bubble contact with endothelial cells in vitro induces calcium influx and IP3-dependent release of calcium stores

    PubMed Central

    Sobolewski, Peter; Kandel, Judith; Klinger, Alexandra L.

    2011-01-01

    Gas embolism is a serious complication of decompression events and clinical procedures, but the mechanism of resulting injury remains unclear. Previous work has demonstrated that contact between air microbubbles and endothelial cells causes a rapid intracellular calcium transient and can lead to cell death. Here we examined the mechanism responsible for the calcium rise. Single air microbubbles (50–150 μm), trapped at the tip of a micropipette, were micromanipulated into contact with individual human umbilical vein endothelial cells (HUVECs) loaded with Fluo-4 (a fluorescent calcium indicator). Changes in intracellular calcium were then recorded via epifluorescence microscopy. First, we confirmed that HUVECs rapidly respond to air bubble contact with a calcium transient. Next, we examined the involvement of extracellular calcium influx by conducting experiments in low calcium buffer, which markedly attenuated the response, or by pretreating cells with stretch-activated channel blockers (gadolinium chloride or ruthenium red), which abolished the response. Finally, we tested the role of intracellular calcium release by pretreating cells with an inositol 1,4,5-trisphosphate (IP3) receptor blocker (xestospongin C) or phospholipase C inhibitor (neomycin sulfate), which eliminated the response in 64% and 67% of cases, respectively. Collectively, our results lead us to conclude that air bubble contact with endothelial cells causes an influx of calcium through a stretch-activated channel, such as a transient receptor potential vanilloid family member, triggering the release of calcium from intracellular stores via the IP3 pathway. PMID:21633077

  18. Changes in Cx43 and NaV1.5 expression precede the occurrence of substantial fibrosis in calcineurin-induced murine cardiac hypertrophy.

    PubMed

    Fontes, Magda S C; Raaijmakers, Antonia J A; van Doorn, Tessa; Kok, Bart; Nieuwenhuis, Sylvia; van der Nagel, Roel; Vos, Marc A; de Boer, Teun P; van Rijen, Harold V M; Bierhuizen, Marti F A

    2014-01-01

    In mice, the calcium-dependent phosphatase calcineurin A (CnA) induces a transcriptional pathway leading to pathological cardiac hypertrophy. Interestingly, induction of CnA has been frequently noticed in human hypertrophic and failing hearts. Independently, the arrhythmia vulnerability of such hearts has been regularly associated with remodeling of parameters determining electrical conduction (expression level of connexin43 (Cx43) and NaV1.5, connective tissue architecture), for which the precise molecular basis and sequence of events is still unknown. Recently, we observed reduced Cx43 and NaV1.5 expression in 4-week old mouse hearts, overexpressing a constitutively active form of CnA (MHC-CnA model), but the order of events is still unknown. Therefore, three key parameters of conduction (Cx43, NaV1.5 and connective tissue expression) were characterized in MHC-CnA ventricles versus wild-type (WT) during postnatal development on a weekly basis. At postnatal week 1, CnA overexpression induced cardiac hypertrophy in MHC-CnA. Moreover, protein and RNA levels of both Cx43 and NaV1.5 were reduced by at least 50% as compared to WT. Cx43 immunoreactive signal was reduced at week 2 in MHC-CnA. At postnatal week 3, Cx43 was less phosphorylated and RNA level of Cx43 normalized to WT values, although the protein level was still reduced. Additionally, MHC-CnA hearts displayed substantial fibrosis relative to WT, which was accompanied by increased RNA levels for genes previously associated with fibrosis such as Col1a1, Col1a2, Col3a1, Tgfb1, Ctgf, Timp1 and microRNA miR-21. In MHC-CnA, reduction in Cx43 and NaV1.5 expression thus coincided with overexpression of CnA and hypertrophy development and preceded significant presence of fibrosis. At postnatal week 4 the alterations in conductional parameters observed in the MHC-CnA model lead to abnormal conduction and arrhythmias, similar to those observed in cardiac remodeling in heart failure patients. The MHC-CnA model, therefore

  19. Lead in calcium supplements.

    PubMed

    Scelfo, G M; Flegal, A R

    2000-04-01

    Intercalibrated measurements of lead in calcium supplements indicate the importance of rigorous analytical techniques to accurately quantify contaminant exposures in complex matrices. Without such techniques, measurements of lead concentrations in calcium supplements may be either erroneously low, by as much as 50%, or below the detection limit needed for new public health criteria. In this study, we determined the lead content of 136 brands of supplements that were purchased in 1996. The calcium in the products was derived from natural sources (bonemeal, dolomite, or oyster shell) or was synthesized and/or refined (chelated and nonchelated calcium). The dried products were acid digested and analyzed for lead by high resolution-inductively coupled plasma-mass spectrometry. The method's limit of quantitation averaged 0.06 microg/g, with a coefficient of variation of 1.7% and a 90-100% lead recovery of a bonemeal standard reference material. Two-thirds of those calcium supplements failed to meet the 1999 California criteria for acceptable lead levels (1.5 microg/daily dose of calcium) in consumer products. The nonchelated synthesized and/or refined calcium products, specifically antacids and infant formulas, had the lowest lead concentrations, ranging from nondetectable to 2.9 microg Pb/g calcium, and had the largest proportion of brands meeting the new criteria (85% of the antacids and 100% of the infant formulas). PMID:10753088

  20. Lead in calcium supplements.

    PubMed Central

    Scelfo, G M; Flegal, A R

    2000-01-01

    Intercalibrated measurements of lead in calcium supplements indicate the importance of rigorous analytical techniques to accurately quantify contaminant exposures in complex matrices. Without such techniques, measurements of lead concentrations in calcium supplements may be either erroneously low, by as much as 50%, or below the detection limit needed for new public health criteria. In this study, we determined the lead content of 136 brands of supplements that were purchased in 1996. The calcium in the products was derived from natural sources (bonemeal, dolomite, or oyster shell) or was synthesized and/or refined (chelated and nonchelated calcium). The dried products were acid digested and analyzed for lead by high resolution-inductively coupled plasma-mass spectrometry. The method's limit of quantitation averaged 0.06 microg/g, with a coefficient of variation of 1.7% and a 90-100% lead recovery of a bonemeal standard reference material. Two-thirds of those calcium supplements failed to meet the 1999 California criteria for acceptable lead levels (1.5 microg/daily dose of calcium) in consumer products. The nonchelated synthesized and/or refined calcium products, specifically antacids and infant formulas, had the lowest lead concentrations, ranging from nondetectable to 2.9 microg Pb/g calcium, and had the largest proportion of brands meeting the new criteria (85% of the antacids and 100% of the infant formulas). Images Figure 1 Figure 2 PMID:10753088

  1. Anoxia Precedes the end-Triassic Mass Extinction: Evidence from the Kennecott Point Formation, British Columbia

    NASA Astrophysics Data System (ADS)

    Kasprak, A. H.; Sepúlveda, J.; Price-Waldman, R.; Williford, K. H.; Whiteside, J. H.; Summons, R. E.

    2011-12-01

    The end-Triassic mass extinction (ETE), at 201.4 million years ago, is one of the five largest ecologic disasters of the Phanerozoic eon. Few geologic sections offer the potential to reconstruct environmental and ecological changes at this time in the marine realm with global significance. The Kennecott Point Formation in Haida Gwaii (formerly the Queen Charlotte Islands), British Columbia, preserves a thick sequence of calcareous shales and siltstones deposited on late Triassic basaltic rocks interpreted to be an oceanic plateau resting within the Panthalassic basin, the largest ocean basin at the time of the Triassic-Jurassic transition. This section, which spans the late Norian to the mid-Hettangian, is plausibly the most representative of the global ocean system at this time; however, environmental reconstructions have been mostly based on bulk carbon and sulfur isotope records. Here, we present a record of molecular fossils (biomarkers) and indices indicative of ecological and redox changes (i.e., algal steranes and bacterial hopanes, gammacerane index, homohopane index, 2- and 3- methyl hopane indices) from the Kennecott Point Formation to argue for a period of low oxygen conditions associated with increased stratification, ecological changes, and disrupted nutrient cycling directly preceding the end-Triassic mass extinction. We couple these results with biomarkers indicative of terrestrial input and vegetation disturbance (tricyclic diterpanes and polycyclic aromatic hydrocarbons) to clarify the relationship between ocean biogeochemistry and environmental changes in the terrestrial realm. This record provides new evidence for changing marine conditions preceding and associated with the ETE and allows for a more rigorous investigation into the chronology of events hypothesized to be mechanistically linked to this mass extinction, including abrupt global warming, major alterations to marine primary productivity, and terrestrial vegetation die-off.

  2. Dual ecdysteroid action on the epitracheal glands and central nervous system preceding ecdysis of Manduca sexta.

    PubMed

    Zitnanová, I; Adams, M E; Zitnan, D

    2001-10-01

    Initiation of the ecdysis behavioural sequence in insects requires activation of the central nervous system (CNS) by pre-ecdysis-triggering hormone (PETH) and ecdysis-triggering hormone (ETH), which are released from the Inka cells of the epitracheal glands. Here, we show that the developmental events preceding larval and pupal ecdysis of Manduca sexta involve a dual action of ecdysteroids on the epitracheal glands and CNS. The low steroid levels in freshly ecdysed and feeding larvae are associated with small-sized epitracheal glands, reduced peptide production in Inka cells and insensitivity of the CNS to ETH. The elevated ecdysteroid levels before each ecdysis lead to a dramatic enlargement of Inka cells and increased production of peptide hormones and their precursors. As blood ecdysteroids reach peak levels, the CNS becomes responsive to Inka cell peptides. These effects of natural ecdysteroid pulses can be experimentally induced by injection of 20-hydroxyecdysone or the ecdysteroid agonist tebufenozide (RH-5992) into ecdysed larvae, thus stimulating peptide production in Inka cells and inducing CNS sensitivity to ETH. A direct steroid action on the CNS is demonstrated by subsequent treatment of isolated nerve cords from ecdysed larvae with 20-hydroxyecdysone and ETH, which results in pre-ecdysis or ecdysis bursts. Our data show that ecdysteroid-induced transcriptional activity in both the epitracheal glands and the CNS are necessary events for the initiation of the ecdysis behavioural sequence. PMID:11707498

  3. Localization suppression and fusion measure of the precedence effect in young children

    NASA Astrophysics Data System (ADS)

    Litovsky, Ruth; Godar, Shelly; Yu, Gongqiang

    2001-05-01

    This study investigated aspects of the precedence effect (PE) known as fusion and localization dominance in children 4-5 years of age. Stimuli were three, 25-ms noise bursts (2-ms rise/fall times) with 250-ms ISI. On PE conditions the lead stimulus was presented from one of six locations in azimuth, and the lag was at 0 deg. Lead-lag delays varied from 5 to 100 ms. Localization was measured using an identification paradigm. Fusion was measured separately whereby subjects reported whether a single auditory event or two auditory events were perceived. Children reported two sounds on 75% of trials (fusion threshold) at delays ranging from 15 to 35 ms. Below fusion thresholds, the localization of the lead was similar to that of single-source stimuli. Above fusion thresholds lead localization was significantly degraded, persisting out to 100 ms. Localization of the lag was poor at all delays on which it was reported as being heard. According to these results localization dominance (difficulty localizing the lag) in children persists at greater delays than fusion, which is consistent with findings obtained in adult subjects. The range of delays over which these effects are robust in children is longer than the range observed in adults.

  4. Histopathological insights into hair loss in Cronkhite-Canada syndrome: diffuse anagen-telogen conversion precedes clinical hair loss progression.

    PubMed

    Watanabe-Okada, Emiko; Inazumi, Toyoko; Matsukawa, Hidehiko; Ohyama, Manabu

    2014-05-01

    Cronkhite-Canada syndrome (CCS) is a rare disorder characterised by gastrointestinal polyposis and ectodermal changes, represented by extensive alopecia. Detailed histopathological investigations of alopecic lesions in two female CCS patients with severe hair loss revealed a marked increase in telogen hair follicles with no sign of loss or of the minaturisation or atrophy of hair follicle structures and the absence of inflammatory change, despite severe inflammation in the gastrointestinal tract. These findings suggested that hair regrowth can be expected without systemic corticosteroids, if they are not necessary for treatment of the gastrointestinal tract, and that anagen-telogen transition is an early event preceding clinical hair loss in CCS. PMID:23714002

  5. Different Neural Patterns Are Associated With Trials Preceding Inhibitory Errors in Children With and Without Attention-Deficit/Hyperactivity Disorder

    PubMed Central

    Spinelli, Simona; Joel, Suresh; Nelson, Tess E.; Vasa, Roma A.; Pekar, James J.; Mostofsky, Stewart H.

    2014-01-01

    Objective Attention-deficit/hyperactivity disorder (ADHD) is associated with difficulty inhibiting impulsive, hyperactive, and off-task behavior. However, no studies have examined whether a distinct pattern of brain activity precedes inhibitory errors in typically developing (TD) children and children with ADHD. In healthy adults, increased activity in the default mode network, a set of brain regions more active during resting or internally focused states, predicts commission errors, suggesting that momentary lapses of attention are related to inhibitory failures. Method Event-related functional magnetic resonance imaging and a go/no-go paradigm were used to explore brain activity preceding errors in 13 children with ADHD and 17 TD controls. Results Comparing pre-error with pre-correct trials, TD children showed activation in the precuneus/posterior cingulate cortex and parahippocampal and middle frontal gyri. In contrast, children with ADHD demonstrated activation in the cerebellum, dorsolateral prefrontal cortex (DLPFC), and basal ganglia. Between-group comparison for the pre-error versus pre-correct contrast showed that children with ADHD showed greater activity in the cerebellum, DLPFC, and ventrolateral PFC compared with TD controls. Results of region-of-interest analysis confirmed that the precuneus/posterior cingulate cortex are more active in TD children compared with children with ADHD. Conclusions These preliminary data suggest that brain activation patterns immediately preceding errors differ between children with ADHD and TD children. In TD children, momentary lapses of attention precede errors, whereas pre-error activity in children with ADHD may be mediated by different circuits, such as those involved in response selection and control. PMID:21703498

  6. Southern Ocean frontal system changes precede Antarctic ice sheet growth during the middle Miocene

    NASA Astrophysics Data System (ADS)

    Kuhnert, Henning; Bickert, Torsten; Paulsen, Harald

    2009-07-01

    The middle Miocene climate approximately 14 Ma ago was characterized by the glaciation of Antarctica, deep-ocean cooling and variations in the global carbon cycle. Although the Southern Ocean underwent significant oceanographic changes, there is limited information on their spatial extent and timing. However, such knowledge is crucial for understanding the role of the Southern Ocean and the Antarctic Circumpolar Current (ACC) for Antarctic glaciation and the coupling between the ocean and continental climate. We have reconstructed surface temperatures and seawater oxygen isotopes at Ocean Drilling Program (ODP) Site 1092 in the Polar Frontal Zone of the Atlantic sector of the Southern Ocean from foraminiferal oxygen isotopes ( δ18O) and magnesium to calcium ratios (Mg/Ca). Sea surface cooling by ~ 4 °C and freshening indicated by the ~ 1‰ reduction of seawater δ18O ( δ18O sw) at 14.2 Ma precede the major step in Antarctic ice sheet growth at 13.8-13.9 Ma. This pattern qualitatively mirrors previous findings from the Pacific sector, and we interpret the surface hydrographic changes to reflect the circum-Antarctic northward shift of the Southern Ocean fronts and specifically at Site 1092 the passage of the Subantarctic Front. The magnitude of change in reconstructed δ18O sw requires a δ18O sw: salinity gradient significantly higher than the modern value (~ 0.52‰) and it possibly exceeded 1.1‰. This implies the Polar Frontal Zone was influenced by freshwater derived from Antarctica, which in turn confirms higher than modern continental precipitation. The latter has previously been suggested to have contributed to Antarctic glaciation.

  7. Self-face enhances processing of immediately preceding invisible faces.

    PubMed

    Pannese, Alessia; Hirsch, Joy

    2011-02-01

    The self-face is thought to be an especially salient stimulus. Behavioral evidence suggests that self-face processing advantage is associated with enhanced processing of temporally adjacent subliminal stimuli. However, the neural basis of this self-related processing modulation has not been investigated. We studied self-face induced signal amplification through masked priming and repetition suppression (fMRI adaptation). Subjects performed a gender-categorization task on self- and non-self target faces preceded by subliminal (17 ms) prime faces. The relationship between prime and target was varied between task-incongruent (when prime and target belonged to a different gender) and task-congruent (when prime and target belonged to the same gender) pairs. We found that, in the presence of the visible self-face (but not of other non-self faces), a bilateral fronto-parietal network exhibited repetition suppression to subliminal prime faces belonging to the same gender (task-congruent) as the target, consistent with the notion that, in the presence of the self-face, subliminal stimuli access high-level processing systems. These results are in agreement with the notion of self-specific top-down amplification of subliminal task-relevant information, and suggest that the self-face, through its high salience, is particularly efficacious in focusing attention. PMID:21168427

  8. High rates of evolution preceded the origin of birds.

    PubMed

    Puttick, Mark N; Thomas, Gavin H; Benton, Michael J

    2014-05-01

    The origin of birds (Aves) is one of the great evolutionary transitions. Fossils show that many unique morphological features of modern birds, such as feathers, reduction in body size, and the semilunate carpal, long preceded the origin of clade Aves, but some may be unique to Aves, such as relative elongation of the forelimb. We study the evolution of body size and forelimb length across the phylogeny of coelurosaurian theropods and Mesozoic Aves. Using recently developed phylogenetic comparative methods, we find an increase in rates of body size and body size dependent forelimb evolution leading to small body size relative to forelimb length in Paraves, the wider clade comprising Aves and Deinonychosauria. The high evolutionary rates arose primarily from a reduction in body size, as there were no increased rates of forelimb evolution. In line with a recent study, we find evidence that Aves appear to have a unique relationship between body size and forelimb dimensions. Traits associated with Aves evolved before their origin, at high rates, and support the notion that numerous lineages of paravians were experimenting with different modes of flight through the Late Jurassic and Early Cretaceous. PMID:24471891

  9. PRECEDENTS FOR AUTHORIZATION OF CONTENTS USING DOSE RATE MEASUREMENTS

    SciTech Connect

    Abramczyk, G.; Bellamy, S.; Nathan, S.; Loftin, B.

    2012-06-05

    For the transportation of Radioactive Material (RAM) packages, the requirements for the maximum allowed dose rate at the package surface and in its vicinity are given in Title 10 of the Code of Federal Regulations, Section 71.47. The regulations are based on the acceptable dose rates to which the public, workers, and the environment may be exposed. As such, the regulations specify dose rates, rather than quantity of radioactive isotopes and require monitoring to confirm the requirements are met. 10CFR71.47 requires that each package of radioactive materials offered for transportation must be designed and prepared for shipment so that under conditions normally incident to transportation the radiation level does not exceed 2 mSv/h (200 mrem/h) at any point on the external Surface of the package, and the transport index does not exceed 10. Before shipment, the dose rate of the package is determined by measurement, ensuring that it conforms to the regulatory limits, regardless of any analyses. This is the requirement for all certified packagings. This paper discusses the requirements for establishing the dose rates when shipping RAM packages and the precedents for meeting these requirements by measurement.

  10. Perfect study, poor evidence: interpretation of biases preceding study design.

    PubMed

    Ioannidis, John P A

    2008-07-01

    In the interpretation of research evidence, data that have been accumulated in a specific isolated study are typically examined. However, important biases may precede the study design. A study may be misleading, useless, or even harmful, even though it seems to be perfectly designed, conducted, analyzed, and reported. Some biases pertain to setting the wider research agenda and include poor scientific relevance, minimal clinical utility, or failure to consider prior evidence (non-consideration of prior evidence, biased consideration of prior evidence, or consideration of biased prior evidence). Other biases reflect issues in setting the specific research questions: examples include straw man effects, avoidance of head-to-head comparisons, head-to-head comparisons bypassing demonstration of effectiveness, overpowered studies, unilateral aims (focusing on benefits and neglecting harms), and the approach of the industry towards research as bulk advertisement (including ghost management of the literature). The concerted presence of such biases may have a multiplicative, detrimental impact on the scientific literature. These issues should be considered carefully when interpreting research results. PMID:18582622

  11. Early Axonopathy Preceding Neurofibrillary Tangles in Mutant Tau Transgenic Mice

    PubMed Central

    Leroy, Karelle; Bretteville, Alexis; Schindowski, Katharina; Gilissen, Emmanuel; Authelet, Michèle; De Decker, Robert; Yilmaz, Zehra; Buée, Luc; Brion, Jean-Pierre

    2007-01-01

    Neurodegenerative diseases characterized by brain and spinal cord involvement often show widespread accumulations of tau aggregates. We have generated a transgenic mouse line (Tg30tau) expressing in the forebrain and the spinal cord a human tau protein bearing two pathogenic mutations (P301S and G272V). These mice developed age-dependent brain and hippocampal atrophy, central and peripheral axonopathy, progressive motor impairment with neurogenic muscle atrophy, and neurofibrillary tangles and had decreased survival. Axonal spheroids and axonal atrophy developed early before neurofibrillary tangles. Neurofibrillary inclusions developed in neurons at 3 months and were of two types, suggestive of a selective vulnerability of neurons to form different types of fibrillary aggregates. A first type of tau-positive neurofibrillary tangles, more abundant in the forebrain, were composed of ribbon-like 19-nm-wide filaments and twisted paired helical filaments. A second type of tau and neurofilament-positive neurofibrillary tangles, more abundant in the spinal cord and the brainstem, were composed of 10-nm-wide neurofilaments and straight 19-nm filaments. Unbiased stereological analysis indicated that total number of pyramidal neurons and density of neurons in the lumbar spinal cord were not reduced up to 12 months in Tg30tau mice. This Tg30tau model thus provides evidence that axonopathy precedes tangle formation and that both lesions can be dissociated from overt neuronal loss in selected brain areas but not from neuronal dysfunction. PMID:17690183

  12. Activation of ras oncogenes preceding the onset of neoplasia

    SciTech Connect

    Kumar, R.; Barbacid, M. ); Sukumar, S. )

    1990-06-01

    The identification of ras oncogenes in human and animal cancers including precancerous lesions indicates that these genes participate in the early stages of neoplastic development. Yet, these observations do not define the timing of ras oncogene activation in the multistep process of carcinogenesis. To ascertain the timing of ras oncogene activation, an animal model system was devised that involves the induction of mammary carcinomas in rats exposed at birth to the carcinogen nitrosomethylurea. High-resolution restriction fragment length polymorphism analysis of polymerase chain reaction-amplified ras sequences revealed the presence of both H-ras and K-ras oncogenes in normal mammary glands 2 weeks after carcinogen treatment and at least 2 months before the onset of neoplasia. These ras oncogenes can remain latent within the mammary gland until exposure to estrogens, demonstrating that activation of ras oncogenes can precede the onset of neoplasia and suggesting that normal physiological proliferative processes such as estrogen-induced mammary gland development may lead to neoplasia if the targeted cells harbor latent ras oncogenes.

  13. Neurological Evidence Linguistic Processes Precede Perceptual Simulation in Conceptual Processing

    PubMed Central

    Louwerse, Max; Hutchinson, Sterling

    2012-01-01

    There is increasing evidence from response time experiments that language statistics and perceptual simulations both play a role in conceptual processing. In an EEG experiment we compared neural activity in cortical regions commonly associated with linguistic processing and visual perceptual processing to determine to what extent symbolic and embodied accounts of cognition applied. Participants were asked to determine the semantic relationship of word pairs (e.g., sky – ground) or to determine their iconic relationship (i.e., if the presentation of the pair matched their expected physical relationship). A linguistic bias was found toward the semantic judgment task and a perceptual bias was found toward the iconicity judgment task. More importantly, conceptual processing involved activation in brain regions associated with both linguistic and perceptual processes. When comparing the relative activation of linguistic cortical regions with perceptual cortical regions, the effect sizes for linguistic cortical regions were larger than those for the perceptual cortical regions early in a trial with the reverse being true later in a trial. These results map upon findings from other experimental literature and provide further evidence that processing of concept words relies both on language statistics and on perceptual simulations, whereby linguistic processes precede perceptual simulation processes. PMID:23133427

  14. Calcium pathway machinery at fertilization in echinoderms

    PubMed Central

    Ramos, Isabela; Wessel, Gary M.

    2016-01-01

    Calcium signaling in cells directs diverse physiological processes. The calcium waves triggered by fertilization is a highly conserved calcium signaling event essential for egg activation, and has been documented in every egg tested. This activity is one of the few highly conserved events of egg activation through the course of evolution. Echinoderm eggs, as well as many other cell types, have three main intracellular Ca2+ mobilizing messengers – IP3, cADPR and NAADP. Both cADPR and NAADP were identified as Ca2+ mobilizing messengers using the sea urchin egg homogenate, and this experimental system, along with the intact urchin and starfish oocyte/egg, continues to be a vital tool for investigating the mechanism of action of calcium signals. While many of the major regulatory steps of the IP3 pathway are well resolved, both cADPR and NAADP remain understudied in terms of our understanding of the fundamental process of egg activation at fertilization. Recently, NAADP has been shown to trigger Ca2+ release from acidic vesicles, separately from the ER, and a new class of calcium channels, the two-pore channels (TPCs), was identified as the likely targets for this messenger. Moreover, it was found that both cADPR and NAADP can be synthesized by the same family of enzymes, the ADP-rybosyl cyclases (ARCs). In this context of increasing amount of information, the potential coupling and functional roles of different messengers, intracellular stores and channels in the formation of the fertilization calcium wave in echinoderms will be critically evaluated. PMID:23218671

  15. [Calcium and health].

    PubMed

    Ortega Anta, Rosa M; Jiménez Ortega, Ana I; López-Sobaler, Ana M

    2015-01-01

    An adequate intake of calcium is only not limited to avoid the risk of osteoporosis and its benefits in longterm bone health, but also it has been linked to protection against various major diseases, such as hypertension, cancer, kidney stones, insulin resistance, diabetes... and several investigations suggest its importance in preventing and controlling obesity. Studies conducted in Spanish representative samples show that a high percentage of adults and children (> 75%) don't achieve the recommended intake of calcium. Moreover, are growing trends among the population suggesting that calcium intake and dairy consumption (main food source of the mineral) are high, and even excessive, in many individuals. This misconception results in that the calcium intake is increasingly far from the recommended one. The maximum tolerable intake of the mineral is fixed at 2.500 mg/day, but this intake is unusual, and it's more disturbing and frequent, to find intakes below the recommended calcium intakes (1.000 and 1.200 mg/day in adults, men and women, respectively). Data from different studies highlight the risk of an inadequate calcium intake and the damages that may affect the health in a long term. It is not about transmitting indiscriminate guidelines in order to increase the intake of calcium / dairy, but the recommended intakes must be met to achieve both the nutritional and health benefits. Also activities for demystification of misconceptions are need, increasingly frequent, that may impair health population. PMID:25862324

  16. Ancient Origins of RGK Protein Function: Modulation of Voltage-Gated Calcium Channels Preceded the Protostome and Deuterostome Split

    PubMed Central

    Puhl, Henry L.; Lu, Van B.; Won, Yu-Jin; Sasson, Yehezkel; Hirsch, Joel A.; Ono, Fumihito; Ikeda, Stephen R.

    2014-01-01

    RGK proteins, Gem, Rad, Rem1, and Rem2, are members of the Ras superfamily of small GTP-binding proteins that interact with Ca2+ channel β subunits to modify voltage-gated Ca2+ channel function. In addition, RGK proteins affect several cellular processes such as cytoskeletal rearrangement, neuronal dendritic complexity, and synapse formation. To probe the phylogenetic origins of RGK protein–Ca2+ channel interactions, we identified potential RGK-like protein homologs in genomes for genetically diverse organisms from both the deuterostome and protostome animal superphyla. RGK-like protein homologs cloned from Danio rerio (zebrafish) and Drosophila melanogaster (fruit flies) expressed in mammalian sympathetic neurons decreased Ca2+ current density as reported for expression of mammalian RGK proteins. Sequence alignments from evolutionarily diverse organisms spanning the protostome/deuterostome divide revealed conservation of residues within the RGK G-domain involved in RGK protein – Cavβ subunit interaction. In addition, the C-terminal eleven residues were highly conserved and constituted a signature sequence unique to RGK proteins but of unknown function. Taken together, these data suggest that RGK proteins, and the ability to modify Ca2+ channel function, arose from an ancestor predating the protostomes split from deuterostomes approximately 550 million years ago. PMID:24992013

  17. Proximal antecedents to violent events in adolescent dating relationships.

    PubMed

    Stephenson, Pamela S; Martsolf, Donna S; Draucker, Claire Burke

    2011-01-01

    Dating violence affects 25-60% of adolescents. This study developed a typology of proximal antecedents to violent events in adolescent dating relationships. Descriptions of 307 dating violence events were extracted from transcribed interviews with 87 young adults who experienced dating violence as adolescents. Verbatim text preceding the description of each violent event was identified as a proximal antecedent. Cross-case analysis was used to develop a typology of five antecedent categories: "pulling away,"  "demanding obedience," "discovering involvement with a rival," "defining the relationship," "demonstrating disrespect." Practitioners can use this typology to engage teens in discussions of factors that precede dating violence events. PMID:21992258

  18. Should we prescribe calcium supplements for osteoporosis prevention?

    PubMed

    Reid, Ian R

    2014-02-01

    Advocacy for the use of calcium supplements arose at a time when there were no other effective interventions for the prevention of osteoporosis. Their promotion was based on the belief that increasing calcium intake would increase bone formation. Our current understandings of the biology of bone suggest that this does not occur, though calcium does act as a weak antiresorptive. Thus, it slows postmenopausal bone loss but, despite this, recent meta-analyses suggest no significant prevention of fractures. In sum, there is little substantive evidence of benefit to bone health from the use of calcium supplements. Against this needs to be balanced the likelihood that calcium supplement use increases cardiovascular events, kidney stones, gastrointestinal symptoms, and admissions to hospital with acute gastrointestinal problems. Thus, the balance of risk and benefit seems to be consistently negative. As a result, current recommendations are to obtain calcium from the diet in preference to supplements. Dietary calcium intake has not been associated with the adverse effects associated with supplements, probably because calcium is provided in smaller boluses, which are absorbed more slowly since they come together with quantities of protein and fat, resulting in a slower gastric transit time. These findings suggest that calcium supplements have little role to play in the modern therapeutics of osteoporosis, which is based around the targeting of safe and effective anti-resorptive drugs to individuals demonstrated to be at increased risk of future fractures. PMID:24707464

  19. Subcellular localization of calcium deposits during zebrafish (Danio rerio) oogenesis.

    PubMed

    Golpour, Amin; Pšenička, Martin; Niksirat, Hamid

    2016-01-01

    Calcium plays prominent roles in regulating a broad range of physiological events in reproduction. The aim of this study was to describe the subcellular distribution of calcium deposits during stages of oogenesis in zebrafish using a combined oxalate-pyroantimonate technique. The oocyte development of zebrafish was categorized into four stages: primary growth, cortical-alveolus, vitellogenic, and maturation, based on morphological criteria. Calcium deposits in the primary growth stage were detected in the cytoplasm, mitochondria, nucleus, and follicular cells. At the cortical-alveolus stage, calcium particles were transported from follicular cells and deposited in the cortical alveoli. In the vitellogenic stage, some cortical alveoli were compacted and transformed from flocculent electron-lucent to electron-dense objects with the progression of the stage. Calcium deposits were transformed from larger to smaller particles, coinciding with compaction of cortical alveoli. In the maturation stage, calcium deposits in all oocyte compartments decreased, with the exception of those in mitochondria. The proportion of area covered by calcium deposits in the mitochondria and cortical alveoli of oocytes at different stages of development was significantly different (p<0.05). The extent of calcium deposits in the cortical alveoli of mature oocytes was substantially lower than in earlier stages. Basic information about calcium distribution during zebrafish oogenesis may contribute to better understanding of its role in oogenesis. PMID:26402915

  20. Combinatorial chemopreventive effect of butyric acid, nicotinamide and calcium glucarate against the 7,12-dimethylbenz(a)anthracene induced mouse skin tumorigenesis attained by enhancing the induction of intrinsic apoptotic events.

    PubMed

    Tiwari, Prakash; Sahay, Satya; Pandey, Manuraj; Qadri, Syed S Y H; Gupta, Krishna P

    2015-01-25

    We explored the basis of the combinatorial chemopreventive effect of butyric acid (BA), nicotinamide (NA) and calcium glucarate (CAG) on mouse skin exposed to 7,12-dimethylbenz(a)anthracene (DMBA). We studied the effects of topical application of DMBA in the presence or absence of BA, NA and CAG on the regulators of apoptosis. DMBA treatment suppressed Bax, Bax/Bcl-2 ratio, release of cyt c, Apaf1, caspase-9, -3 mediated apoptosis. Downregulation of p21 and upregulation of Bcl-2, mut p53 were also observed in only DMBA treated mice. Simultaneous application of BA, NA and CAG induced a mitochondria-mediated apoptosis, characterized by a rise in the Bax, Bax/Bcl-2 ratio, release of cyt c, upregulation of Apaf1 with down-stream activation of caspase-9, -3. Furthermore treatment with BA, NA and CAG demonstrated an upregulation of p21 and downregulation of Bcl-2, mut p53. But this effect was enhanced in the presence of all the three compounds together in combination. Chemoprevention by a combination of BA, NA and CAG by inducing the apoptosis, the natural cell death, suggest the importance of the potential combinational strategies capable of preventing skin tumor development. PMID:25478867

  1. Regionalized calcium signaling in zebrafish fertilization.

    PubMed

    Sharma, Dipika; Kinsey, William H

    2008-01-01

    calcium signaling in the zebrafish oocyte requires attention to morphologically distinct compartments of the oocyte and it is likely that these compartments are controlled by different biochemical events. PMID:18649270

  2. Calcium's role in mechanotransduction during muscle development.

    PubMed

    Benavides Damm, Tatiana; Egli, Marcel

    2014-01-01

    Mechanotransduction is a process where cells sense their surroundings and convert the physical forces in their environment into an appropriate response. Calcium plays a crucial role in the translation of such forces to biochemical signals that control various biological processes fundamental in muscle development. The mechanical stimulation of muscle cells may for example result from stretch, electric and magnetic stimulation, shear stress, and altered gravity exposure. The response, mainly involving changes in intracellular calcium concentration then leads to a cascade of events by the activation of downstream signaling pathways. The key calcium-dependent pathways described here include the nuclear factor of activated T cells (NFAT) and mitogen-activated protein kinase (MAPK) activation. The subsequent effects in cellular homeostasis consist of cytoskeletal remodeling, cell cycle progression, growth, differentiation, and apoptosis, all necessary for healthy muscle development, repair, and regeneration. A deregulation from the normal process due to disuse, trauma, or disease can result in a clinical condition such as muscle atrophy, which entails a significant loss of muscle mass. In order to develop therapies against such diseased states, we need to better understand the relevance of calcium signaling and the downstream responses to mechanical forces in skeletal muscle. The purpose of this review is to discuss in detail how diverse mechanical stimuli cause changes in calcium homeostasis by affecting membrane channels and the intracellular stores, which in turn regulate multiple pathways that impart these effects and control the fate of muscle tissue. PMID:24525559

  3. Calcium/Vitamin D Supplementation and Coronary Artery Calcification

    PubMed Central

    Manson, JoAnn E.; Allison, Matthew A.; Carr, J. Jeffrey; Langer, Robert D.; Cochrane, Barbara B.; Hendrix, Susan L.; Hsia, Judith; Hunt, Julie R.; Lewis, Cora E.; Margolis, Karen L.; Robinson, Jennifer G.; Rodabough, Rebecca J.; Thomas, Asha M.

    2010-01-01

    Objectives Coronary artery calcified plaque is a marker for atheromatous plaque burden and predicts future risk of cardiovascular events. The relationship between calcium plus vitamin D supplementation and coronary artery calcium (CAC) has not been previously assessed in a randomized trial setting. We compared coronary artery calcium scores among women randomized to calcium/vitamin D supplementation versus placebo following trial completion. Methods In an ancillary substudy of women randomized to calcium carbonate (1000 mg of elemental calcium daily) plus vitamin D3 (400 IU daily) versus placebo, nested within the Women’s Health Initiative trial of estrogen among women with hysterectomy, we measured CAC with cardiac computed tomography in 754 women aged 50–59 years at randomization. Imaging for CAC was performed at 28 of 40 centers following a mean of 7 years of treatment and scans were read centrally. Coronary artery calcium scores were measured by a central reading center with masking to randomization assignments. Results Post-trial CAC measurements were similar in women randomized to calcium/vitamin D supplementation (calcium/D) and those receiving placebo. The mean CAC score was 91.6 for calcium/D and 100.5 for placebo (rank test p-value=0.74). After adjustment for coronary risk factors, multivariate odds ratios for increasing CAC score cutpoints (CAC >0, ≥10, and ≥100) for calcium/D vs placebo were 0.92 (95% confidence interval, 0.64–1.34), 1.29 (0.88–1.87), and 0.90 (0.56–1.44), respectively. Corresponding odds ratios among women with >50% adherence to study pills and for higher levels of CAC (>300), were similar. Conclusions Treatment with moderate doses of calcium plus vitamin D3 did not appear to alter coronary artery calcified plaque burden among postmenopausal women. PMID:20551849

  4. Oral Hygiene Behaviors and Caries Experience in Northwest PRECEDENT Patients

    PubMed Central

    Rothen, Marilynn; Cunha-Cruz, Joana; Zhou, Lingmei; Mancl, Lloyd; Jones, Jackie S.; Berg, Joel

    2014-01-01

    Objectives To investigate the association between oral hygiene behaviors (toothbrushing, water rinsing after brushing, interproximal cleaning, and adjunctive use of fluoride products) and recent caries (past 24 months) in a random sample of patients in Northwest PRECEDENT practices. Methods Practitioner-members of Northwest PRECEDENT dental Practice-based Research Network (PBRN) conducted a longitudinal study on caries risk assessment. At baseline patients completed a questionnaire on oral self-care, snacking, health, and socio-demographics. A dental exam recorded readily-visible heavy plaque and DMFT; chart review captured new caries and treatments in the previous 24 months. Bivariate and multiple GEE log-linear regression models stratified by age groups were used to relate oral hygiene behaviors to the primary outcome of mean dental caries in the past 24 months on data from 1400 patients in 63 practices. The primary exposure of interest was fluoride toothbrushing frequency. Results Fluoride toothbrushing once per day or more by patients 9-17 was significantly associated with a 50% lower mean caries rate compared to fluoride toothbrushing less than once per day, after adjustment for age, gender, race, education, income, between-meal carbohydrate snacks, sugar-added beverages, alcohol consumption, smoking, BMI, exercise, stimulated salivary pH, number of teeth, and all other oral hygiene behaviors captured [Rate Ratio (RR)=0.5; 95% confidence interval (CI)=0.3-0.8]. After adjustment, for patients 18-64 fluoride toothbrushing two or more times per day was significantly associated with a 40% lower recent mean caries rate (RR=0.6; 95%CI=0.4-0.9); in patients 65+, twice a day or more fluoride toothbrushing was not associated with lower caries rates (RR=1.1; 95%CI=0.7-1.8). Of the other oral hygiene variables, after adjustment, patients 18-64 who rinsed with water after brushing had a 40% lower mean caries rate compared to no rinsing (RR=0.6; 95%CI=0.4-0.9) and the

  5. Axonal Dysfunction Precedes Motor Neuronal Death in Amyotrophic Lateral Sclerosis.

    PubMed

    Iwai, Yuta; Shibuya, Kazumoto; Misawa, Sonoko; Sekiguchi, Yukari; Watanabe, Keisuke; Amino, Hiroshi; Kuwabara, Satoshi

    2016-01-01

    Wide-spread fasciculations are a characteristic feature in amyotrophic lateral sclerosis (ALS), suggesting motor axonal hyperexcitability. Previous excitability studies have shown increased nodal persistent sodium conductances and decreased potassium currents in motor axons of ALS patients, both of the changes inducing hyperexcitability. Altered axonal excitability potentially contributes to motor neuron death in ALS, but the relationship of the extent of motor neuronal death and abnormal excitability has not been fully elucidated. We performed multiple nerve excitability measurements in the median nerve at the wrist of 140 ALS patients and analyzed the relationship of compound muscle action potential (CMAP) amplitude (index of motor neuronal loss) and excitability indices, such as strength-duration time constant, threshold electrotonus, recovery cycle and current-threshold relationships. Compared to age-matched normal controls (n = 44), ALS patients (n = 140) had longer strength-duration time constant (SDTC: a measure of nodal persistent sodium current; p < 0.05), greater threshold changes in depolarizing threshold electrotonus (p < 0.05) and depolarizing current threshold relationship (i.e. less accommodation; (p < 0.05), greater superexcitability (a measure of fast potassium current; p < 0.05) and reduced late subexcitability (a measure of slow potassium current; p < 0.05), suggesting increased persistent sodium currents and decreased potassium currents. The reduced potassium currents were found even in the patient subgroups with normal CMAP (> 5mV). Regression analyses showed that SDTC (R = -0.22) and depolarizing threshold electrotonus (R = -0.22) increased with CMAP decline. These findings suggest that motor nerve hyperexcitability occurs in the early stage of the disease, and precedes motor neuronal loss in ALS. Modulation of altered ion channel function could be a treatment option for ALS. PMID:27383069

  6. Axonal Dysfunction Precedes Motor Neuronal Death in Amyotrophic Lateral Sclerosis

    PubMed Central

    Iwai, Yuta; Shibuya, Kazumoto; Misawa, Sonoko; Sekiguchi, Yukari; Watanabe, Keisuke; Amino, Hiroshi; Kuwabara, Satoshi

    2016-01-01

    Wide-spread fasciculations are a characteristic feature in amyotrophic lateral sclerosis (ALS), suggesting motor axonal hyperexcitability. Previous excitability studies have shown increased nodal persistent sodium conductances and decreased potassium currents in motor axons of ALS patients, both of the changes inducing hyperexcitability. Altered axonal excitability potentially contributes to motor neuron death in ALS, but the relationship of the extent of motor neuronal death and abnormal excitability has not been fully elucidated. We performed multiple nerve excitability measurements in the median nerve at the wrist of 140 ALS patients and analyzed the relationship of compound muscle action potential (CMAP) amplitude (index of motor neuronal loss) and excitability indices, such as strength-duration time constant, threshold electrotonus, recovery cycle and current-threshold relationships. Compared to age-matched normal controls (n = 44), ALS patients (n = 140) had longer strength-duration time constant (SDTC: a measure of nodal persistent sodium current; p < 0.05), greater threshold changes in depolarizing threshold electrotonus (p < 0.05) and depolarizing current threshold relationship (i.e. less accommodation; (p < 0.05), greater superexcitability (a measure of fast potassium current; p < 0.05) and reduced late subexcitability (a measure of slow potassium current; p < 0.05), suggesting increased persistent sodium currents and decreased potassium currents. The reduced potassium currents were found even in the patient subgroups with normal CMAP (> 5mV). Regression analyses showed that SDTC (R = -0.22) and depolarizing threshold electrotonus (R = -0.22) increased with CMAP decline. These findings suggest that motor nerve hyperexcitability occurs in the early stage of the disease, and precedes motor neuronal loss in ALS. Modulation of altered ion channel function could be a treatment option for ALS. PMID:27383069

  7. Integrated Vehicle Ground Vibration Testing of Manned Spacecraft: Historical Precedent

    NASA Technical Reports Server (NTRS)

    Lemke, Paul R.; Tuma, Margaret L.; Askins, Bruce R.

    2008-01-01

    For the first time in nearly 30 years, NASA is developing a new manned space flight launch system. The Ares I will carry crew and cargo to not only the International Space Station, but onward for the future exploration of the Moon and Mars. The Ares I control system and structural designs use complex computer models for their development. An Integrated Vehicle Ground Vibration Test (IVGVT) will validate the efficacy of these computer models. The IVGVT will reduce the technical risk of unexpected conditions that could place the vehicle or crew in jeopardy. The Ares Project Office's Flight and Integrated Test Office commissioned a study to determine how historical programs, such as Saturn and Space Shuttle, validated the structural dynamics of an integrated flight vehicle. The study methodology was to examine the historical record and seek out members of the engineering community who recall the development of historic manned launch vehicles. These records and interviews provided insight into the best practices and lessons learned from these historic development programs. The information that was gathered allowed the creation of timelines of the historic development programs. The timelines trace the programs from the development of test articles through test preparation, test operations, and test data reduction efforts. These timelines also demonstrate how the historical tests fit within their overall vehicle development programs. Finally, the study was able to quantify approximate staffing levels during historic development programs. Using this study, the Flight and Integrated Test Office was able to evaluate the Ares I Integrated Vehicle Ground Vibration Test schedule and workforce budgets in light of the historical precedents to determine if the test had schedule or cost risks associated with it.

  8. Impaired cortical mitochondrial function following TBI precedes behavioral changes

    PubMed Central

    Watson, William D.; Buonora, John E.; Yarnell, Angela M.; Lucky, Jessica J.; D’Acchille, Michaela I.; McMullen, David C.; Boston, Andrew G.; Kuczmarski, Andrew V.; Kean, William S.; Verma, Ajay; Grunberg, Neil E.; Cole, Jeffrey T.

    2014-01-01

    Traumatic brain injury (TBI) pathophysiology can be attributed to either the immediate, primary physical injury, or the delayed, secondary injury which begins minutes to hours after the initial injury and can persist for several months or longer. Because these secondary cascades are delayed and last for a significant time period post-TBI, they are primary research targets for new therapeutics. To investigate changes in mitochondrial function after a brain injury, both the cortical impact site and ipsilateral hippocampus of adult male rats 7 and 17 days after a controlled cortical impact (CCI) injury were examined. State 3, state 4, and uncoupler-stimulated rates of oxygen consumption, respiratory control ratios (RCRs) were measured and membrane potential quantified, and all were significantly decreased in 7 day post-TBI cortical mitochondria. By contrast, hippocampal mitochondria at 7 days showed only non-significant decreases in rates of oxygen consumption and membrane potential. NADH oxidase activities measured in disrupted mitochondria were normal in both injured cortex and hippocampus at 7 days post-CCI. Respiratory and phosphorylation capacities at 17 days post-CCI were comparable to naïve animals for both cortical and hippocampus mitochondria. However, unlike oxidative phosphorylation, membrane potential of mitochondria in the cortical lining of the impact site did not recover at 17 days, suggesting that while diminished cortical membrane potential at 17 days does not adversely affect mitochondrial capacity to synthesize ATP, it may negatively impact other membrane potential-sensitive mitochondrial functions. Memory status, as assessed by a passive avoidance paradigm, was not significantly impaired until 17 days after injury. These results indicate pronounced disturbances in cortical mitochondrial function 7 days after CCI which precede the behavioral impairment observed at 17 days. PMID:24550822

  9. Increased cerebral oxygenation precedes generalized tonic clonic seizures.

    PubMed

    Moseley, Brian D; Britton, Jeffrey W; So, Elson

    2014-11-01

    Based on previous fMRI and SPECT studies, it has been suggested seizures may be preceded by increased cerebral blood flow. Recently, we demonstrated transcutaneous regional cerebral oxygen saturation (rSO2) sensors are feasible for use in patients undergoing video EEG monitoring. We reanalyzed our data to determine if seizures were consistently marked by increased cerebral oxygenation. Patients with histories of generalized tonic clonic seizures (GTCS) were recruited into our study. All subjects were evaluated with continuous 30-channel scalp EEG and 2 rSO2 sensors placed on each side of the forehead. We calculated the mean rSO2 value for the 1h epochs in the non-ictal (2h prior to seizure onset) and pre-ictal (1h prior to onset) periods. Seven primary/secondarily GTCS from 5 patients were captured. The mean rSO2 value in the non-ictal period was 75.6 ± 5.7%. This increased to 76.0 ± 6% in the pre-ictal period (p=0.032). Four of the 7GTCS (57.1%) were marked by ≥ 3 sequential rSO2 values in the pre-ictal period that were ≥ 3 SDs greater than the mean non-ictal rSO2 value. Three GTCS (42.9%) were marked by sustained cerebral hyperemia for ≥ 15 consecutive readings. Our results suggest increased cerebral blood flow could be non-invasively used to predict seizure occurrence. PMID:25277885

  10. Get Enough Calcium

    MedlinePlus

    ... Previous section Overview 2 of 4 sections Take Action! Take Action: Calcium Sources Protect your bones – get plenty of ... Foods and Vitamins 3 of 4 sections Take Action: Vitamin D Get enough vitamin D. Vitamin D ...

  11. Stoichiometry of Calcium Medicines

    ERIC Educational Resources Information Center

    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.

  12. Calcium in diet

    MedlinePlus

    ... level based on scientific research evidence. Adequate Intake (AI): This level is established when there is not ... enough calcium from the foods they eat. Infants (AI) 0 to 6 months: 200 milligrams per day ( ...

  13. Calcium pyrophosphate arthritis

    MedlinePlus

    ... that can cause attacks of arthritis. Like with gout, crystals form in the joints. But in calcium ... pyrophosphate arthritis can be misdiagnosed as: Gouty arthritis (gout) Osteoarthritis Rheumatoid arthritis

  14. Calcium Signaling and Meiotic Exit at Fertilization in Xenopus Egg

    PubMed Central

    Tokmakov, Alexander A.; Stefanov, Vasily E.; Iwasaki, Tetsushi; Sato, Ken-Ichi; Fukami, Yasuo

    2014-01-01

    Calcium is a universal messenger that mediates egg activation at fertilization in all sexually reproducing species studied. However, signaling pathways leading to calcium generation and the mechanisms of calcium-induced exit from meiotic arrest vary substantially among species. Here, we review the pathways of calcium signaling and the mechanisms of meiotic exit at fertilization in the eggs of the established developmental model, African clawed frog, Xenopus laevis. We also discuss calcium involvement in the early fertilization-induced events in Xenopus egg, such as membrane depolarization, the increase in intracellular pH, cortical granule exocytosis, cortical contraction, contraction wave, cortical rotation, reformation of the nuclear envelope, sperm chromatin decondensation and sister chromatid segregation. PMID:25322156

  15. Cyclic modulation of enzymes of pyrimidine nucleotide biosynthesis precedes sialoglycoconjugate changes during 2-acetylaminofluorene-induced hepatocarcinogenesis in the rat.

    PubMed

    Elliott, W L; Sawick, D P; DeFrees, S A; Heinstein, P F; Cassady, J M; Morré, D J

    1984-07-30

    Three enzymatic activities associated with pyrimidine nucleotide biosynthesis were monitored at weekly or bi-weekly intervals during 2-acetylaminofluorene- (0.025% in a Farber Basal Carcinogenic diet) induced hepatocarcinogenesis in the rat. Dihydroorotate dehydrogenase, the fourth of six enzymes in de novo pyrimidine biosynthesis, declined in activity while UDP kinase and CTP synthetase showed sequential increases in activity. The alterations in activity appeared to be cyclic, followed by a full or partial return to control values. Three full cycles were monitored. The first cycle preceded nodule formation. The second cycle accompanied nodule formation and preceded sialoglycoconjugate changes reported previously. The third cycle accompanied the early glycoconjugate changes. The cyclic pattern was reproducible in three separate experiments. In each cycle, the order of events was as follows: decrease in dihydroorotate dehydrogenase, sequential increases in UDP kinase, CTP synthetase and CMPsialic acid synthase, and finally increases in the enzyme lactosylceramide: CMPsialic acid sialyltransferase, lipid-soluble sialic acid and total sialic acid. In livers of animals fed 1.87% of the hepatotoxin, 4-acetamidophenol, no biochemical alterations resembling those induced by 2-acetylaminofluorene were obtained, despite acute centrilobular necrosis of the livers. The findings point to a biochemical cascade beginning with administration of carcinogen and continuing through the development of hyperplastic nodules and of frank carcinomas resulting not from hepatotoxicity but as events associated with the hepatocarcinogenic progression. PMID:6331524

  16. Analysis of Intracellular Calcium Signaling in Human Embryonic Stem Cells.

    PubMed

    Péntek, Adrienn; Pászty, Katalin; Apáti, Ágota

    2016-01-01

    Measurement of changes in intracellular calcium concentration is one of the most common and useful tools for studying signal transduction pathways or cellular responses in basic research and drug screening purposes as well. Increasing number of such applications using human pluripotent stem cells and their derivatives requires development of calcium signal measurements for this special cell type. Here we describe a modified protocol for analysis of calcium signaling events in human embryonic stem cells, which can be used for other pluripotent cell types (such as iPSC) or their differentiated offspring as well. PMID:24482125

  17. Inhibition of gravitropism in oat coleoptiles by calcium chelation

    NASA Technical Reports Server (NTRS)

    Roux, S. J.

    1984-01-01

    Some cellular event necessary for gravitropism is inhibited by EGTA without interferring with the overall growth. Calcium relieves this inhibition and demonstrates both that inhibition is reversible and was probably due to a reduction in the ability to free calcium required for one or more at the transduction steps of gravitropism. At the near neutral pH used, EGTA is charged and would not be expected to readily cross the membrane. One of its primary effects, then, is probably the bringing of free calcium in the apoplastic space exterior to the cell membranes.

  18. Rising catch variability preceded historical fisheries collapses in Alaska.

    PubMed

    Litzow, Michael A; Mueter, Franz J; Urban, J Daniel

    2013-09-01

    Statistical indicators such as rising variance and rising skewness in key system parameters may provide early warning of "regime shifts" in communities and populations. However, the utility of these indicators has rarely been tested in the large, complex ecosystems that are of most interest to managers. Crustacean fisheries in the Gulf of Alaska and Bering Sea experienced a series of collapses beginning in the 1970s, and we used spatially resolved catch data from these fisheries to test the predictions that increasing variability and skewness would precede stock collapse. Our data set consisted of catch data from 14 fisheries (12 collapsing and two non-collapsing), spanning 278 cumulative years. Our sampling unit for analysis was the Alaska Department of Fish and Game statistical reporting area (mean n for individual fisheries = 42 areas, range 7-81). We found that spatial variability in catches increased prior to stock collapse: a random-effects model estimating trend in variability across all 12 collapsing fisheries showed strong evidence of increasing variability prior to collapse. Individual trends in variability were statistically significant for only four of the 12 collapsing fisheries, suggesting that rising variability might be most effective as an indicator when information from multiple populations is available. Analyzing data across multiple fisheries allowed us to detect increasing variability 1-4 years prior to collapse, and trends in variability were significantly different for collapsing and non-collapsing fisheries. In spite of theoretical expectations, we found no evidence of pre-collapse increases in catch skewness. Further, while models generally predict that rising variability should be a transient phenomenon around collapse points, increased variability was a persistent feature of collapsed fisheries in our study. We conclude that this result is more consistent with fishing effects as the cause of increased catch variability, rather than the

  19. Calcium transport, thiol status, and hepatotoxicity following N-nitrosodimethylamine exposure in mice

    SciTech Connect

    Reitman, F.A.; Berger, M.L.; Minnema, D.J.; Shertzer, H.G.

    1988-01-01

    The hepatotoxicant N-nitrosodimethylamine (NDMA) is presumed to exert toxicity through reactive metabolites. NDMA is similar in this respect to numerous other hepatotoxicants, for which hepatotoxicity is also associated with a rapid depletion of soluble and/or protein thiols, and an inhibition of calcium transport systems. The authors examined the hypothesis that hepatotoxicity for NDMA is preceded by thiol depletion and/or inhibition of calcium transport in isolated liver subcellular fractions. Centrizonal liver necrosis in mice was evident at 24 but not at 12 h subsequent to intraperitoneal administration of 40 mg NDMA/kg. Hepatotoxicity was not preceded by depletion of liver protein-free sulfhydryls, nor by protein sulfhydryl depletion in liver whole homogenate, microsomal, or plasma membrane fractions. NDMA-mediated toxicity was also not preceded by inhibition of calcium uptake capability by microsomal, mitochondrial, or plasma membrane fractions. In contrast, carbon tetrachloride produced the expected rapid decrease in microsomal calcium uptake capability, followed by a centrizonal necrosis that was maximal at about 24 h. These studies suggest that the mechanism of NDMA hepatotoxicity may differ from that of a number of other hepatotoxicants (e.g., carbon tetrachloride, acetaminophen, bromobenzene) for which toxicity is also mediated through reactive metabolites.

  20. Strong and Anomalous Thermal Expansion Precedes the Thermosalient Effect in Dynamic Molecular Crystals

    NASA Astrophysics Data System (ADS)

    Panda, Manas K.; Centore, Roberto; Causà, Mauro; Tuzi, Angela; Borbone, Fabio; Naumov, Panče

    2016-07-01

    The ability of thermosalient solids, organic analogues of inorganic martensites, to move by rapid mechanical reconfiguration or ballistic event remains visually appealing and potentially useful, yet mechanistically elusive phenomenon. Here, with a material that undergoes both thermosalient and non-thermosalient phase transitions, we demonstrate that the thermosalient effect is preceded by anomalous thermal expansion of the unit cell. The crystal explosion occurs as sudden release of the latent strain accumulated during the anisotropic, exceedingly strong expansion of the unit cell with αa = 225.9 × 10‑6 K‑1, αb = 238.8 × 10‑6 K‑1 and αc = ‑290.0 × 10‑6 K‑1, the latter being the largest negative thermal expansivity observed for an organic compound thus far. The results point out to the occurence of the thermosalient effect in phase transitions as means to identify new molecular materials with strong positive and/or negative thermal expansion which prior to this work could only be discovered serendipitously.

  1. The influence of preceding dive cycles on the foraging decisions of Antarctic fur seals

    PubMed Central

    Iwata, T.; Sakamoto, K. Q.; Edwards, E. W. J.; Staniland, I. J.; Trathan, P. N.; Goto, Y.; Sato, K.; Naito, Y.; Takahashi, A.

    2015-01-01

    The foraging strategy of many animals is thought to be determined by their past experiences. However, few empirical studies have investigated whether this is true in diving animals. We recorded three-dimensional movements and mouth-opening events from three Antarctic fur seals during their foraging trips to examine how they adapt their behaviour based on past experience—continuing to search for prey in the same area or moving to search in a different place. Each dive cycle was divided into a transit phase and a feeding phase. The linear horizontal distance travelled after feeding phases in each dive was affected by the mouth-opening rate during the previous 244 s, which typically covered two to three dive cycles. The linear distance travelled tended to be shorter when the mouth-opening rate in the previous 244 s was higher, i.e. seals tended to stay in the same areas with high prey-encounter rates. These results indicate that Antarctic fur seals follow decision-making strategies based on the past foraging experience over time periods longer than the immediately preceding dive. PMID:26156132

  2. Volcanic and seismic activity at Stromboli preceding the 2002-2003 flank eruption

    NASA Astrophysics Data System (ADS)

    Burton, M.; Calvari, S.; Spampinato, L.; Lodato, L.; Pino, N. A.; Marchetti, E.; Murè, F.

    Regular surveys with a thermal camera from both ground- and helicopter-based surveys have been carried out on Stromboli since October 2001. This data set allowed us to detect morphological changes in Stromboli's summit craters produced by major explosions and to track an increase in volcanic activity associated with a heightened magma level within the main conduit that preceded the 2002-2003 effusive eruption. Together with thermal measurements, geophysical surveys performed in May and September/October 2002 highlighted clear increases in the amplitude of very long period (VLP) events, consistent with the ascent of the magma column above the VLP source region. The increased magma level was probably induced by elevated pressure in the deep feeding system, controlled by regional tectonic stress. This, in turn, pressurized the uppermost part of the crater terrace, producing greater soil permeability and soil degassing. Eventually, the magma loading caused the NW flank of the summit craters to fracture, allowing lava to flood out at high effusion rates on 28 December 2002, starting an approximately 6-month-long effusive eruption.

  3. Defects During Mecp2 Null Embryonic Cortex Development Precede the Onset of Overt Neurological Symptoms.

    PubMed

    Bedogni, Francesco; Cobolli Gigli, Clementina; Pozzi, Davide; Rossi, Riccardo Lorenzo; Scaramuzza, Linda; Rossetti, Grazisa; Pagani, Massimiliano; Kilstrup-Nielsen, Charlotte; Matteoli, Michela; Landsberger, Nicoletta

    2016-06-01

    MeCP2 is associated with several neurological disorders; of which, Rett syndrome undoubtedly represents the most frequent. Its molecular roles, however, are still unclear, and data from animal models often describe adult, symptomatic stages, while MeCP2 functions during embryonic development remain elusive. We describe the pattern and timing of Mecp2 expression in the embryonic neocortex highlighting its low but consistent expression in virtually all cells and show the unexpected occurrence of transcriptional defects in the Mecp2 null samples at a stage largely preceding the onset of overt symptoms. Through the deregulated expression of ionic channels and glutamatergic receptors, the lack of Mecp2 during early neuronal maturation leads to the reduction in the neuronal responsiveness to stimuli. We suggest that such features concur to morphological alterations that begin affecting Mecp2 null neurons around the perinatal age and become evident later in adulthood. We indicate MeCP2 as a key modulator of the transcriptional mechanisms regulating cerebral cortex development. Neurological phenotypes of MECP2 patients could thus be the cumulative result of different adverse events that are already present at stages when no obvious signs of the pathology are evident and are worsened by later impairments affecting the central nervous system during maturation and maintenance of its functionality. PMID:25979088

  4. Strong and Anomalous Thermal Expansion Precedes the Thermosalient Effect in Dynamic Molecular Crystals

    PubMed Central

    Panda, Manas K.; Centore, Roberto; Causà, Mauro; Tuzi, Angela; Borbone, Fabio; Naumov, Panče

    2016-01-01

    The ability of thermosalient solids, organic analogues of inorganic martensites, to move by rapid mechanical reconfiguration or ballistic event remains visually appealing and potentially useful, yet mechanistically elusive phenomenon. Here, with a material that undergoes both thermosalient and non-thermosalient phase transitions, we demonstrate that the thermosalient effect is preceded by anomalous thermal expansion of the unit cell. The crystal explosion occurs as sudden release of the latent strain accumulated during the anisotropic, exceedingly strong expansion of the unit cell with αa = 225.9 × 10−6 K−1, αb = 238.8 × 10−6 K−1 and αc = −290.0 × 10−6 K−1, the latter being the largest negative thermal expansivity observed for an organic compound thus far. The results point out to the occurence of the thermosalient effect in phase transitions as means to identify new molecular materials with strong positive and/or negative thermal expansion which prior to this work could only be discovered serendipitously. PMID:27403616

  5. Nondisjunctional segregations in Drosophila female meiosis I are preceded by homolog malorientation at metaphase arrest.

    PubMed

    Gillies, Shane C; Lane, Fiona M; Paik, Wonbeom; Pyrtel, Khateriaa; Wallace, Nneka T; Gilliland, William D

    2013-02-01

    The model of Drosophila female meiosis I was recently revised by the discovery that chromosome congression precedes metaphase I arrest. Use of the prior framework to interpret data from meiotic mutants led to the conclusion that chromosome segregation errors (nondisjunction, NDJ) occurred when nonexchange chromosomes moved out on the spindle in a maloriented configuration and became trapped there at metaphase arrest. The discovery that congression returns nonexchange chromosomes to the metaphase plate invalidates this interpretation and raises the question of what events actually do lead to NDJ. To address this, we have assayed an allelic series of ald (mps1) meiotic mutants that complete congression at wild-type rates, but have widely varying NDJ rates in an otherwise isogenic background, as well as a nod mutant background that primarily undergoes loss of chromosome 4. Using genetic assays to measure NDJ rates, and FISH assays to measure chromosome malorientation rates in metaphase-arrested oocytes, shows that these two rates are highly correlated across ald mutants, suggesting that malorientation during congression commits these chromosomes to eventually nondisjoin. Likewise, the rate of chromosome loss observed in nod is similar to the rate at which these chromosomes fail to associate with the main chromosome mass. Together these results provide a proximal mechanism for how these meiotic mutants cause NDJ and chromosome loss and improve our understanding of how prometaphase chromosome congression relates to anaphase chromosome segregation. PMID:23222652

  6. Nondisjunctional Segregations in Drosophila Female Meiosis I Are Preceded by Homolog Malorientation at Metaphase Arrest

    PubMed Central

    Gillies, Shane C.; Lane, Fiona M.; Paik, Wonbeom; Pyrtel, Khateriaa; Wallace, Nneka T.; Gilliland, William D.

    2013-01-01

    The model of Drosophila female meiosis I was recently revised by the discovery that chromosome congression precedes metaphase I arrest. Use of the prior framework to interpret data from meiotic mutants led to the conclusion that chromosome segregation errors (nondisjunction, NDJ) occurred when nonexchange chromosomes moved out on the spindle in a maloriented configuration and became trapped there at metaphase arrest. The discovery that congression returns nonexchange chromosomes to the metaphase plate invalidates this interpretation and raises the question of what events actually do lead to NDJ. To address this, we have assayed an allelic series of ald (mps1) meiotic mutants that complete congression at wild-type rates, but have widely varying NDJ rates in an otherwise isogenic background, as well as a nod mutant background that primarily undergoes loss of chromosome 4. Using genetic assays to measure NDJ rates, and FISH assays to measure chromosome malorientation rates in metaphase-arrested oocytes, shows that these two rates are highly correlated across ald mutants, suggesting that malorientation during congression commits these chromosomes to eventually nondisjoin. Likewise, the rate of chromosome loss observed in nod is similar to the rate at which these chromosomes fail to associate with the main chromosome mass. Together these results provide a proximal mechanism for how these meiotic mutants cause NDJ and chromosome loss and improve our understanding of how prometaphase chromosome congression relates to anaphase chromosome segregation. PMID:23222652

  7. Strong and Anomalous Thermal Expansion Precedes the Thermosalient Effect in Dynamic Molecular Crystals.

    PubMed

    Panda, Manas K; Centore, Roberto; Causà, Mauro; Tuzi, Angela; Borbone, Fabio; Naumov, Panče

    2016-01-01

    The ability of thermosalient solids, organic analogues of inorganic martensites, to move by rapid mechanical reconfiguration or ballistic event remains visually appealing and potentially useful, yet mechanistically elusive phenomenon. Here, with a material that undergoes both thermosalient and non-thermosalient phase transitions, we demonstrate that the thermosalient effect is preceded by anomalous thermal expansion of the unit cell. The crystal explosion occurs as sudden release of the latent strain accumulated during the anisotropic, exceedingly strong expansion of the unit cell with αa = 225.9 × 10(-6) K(-1), αb = 238.8 × 10(-6) K(-1) and αc = -290.0 × 10(-6) K(-1), the latter being the largest negative thermal expansivity observed for an organic compound thus far. The results point out to the occurence of the thermosalient effect in phase transitions as means to identify new molecular materials with strong positive and/or negative thermal expansion which prior to this work could only be discovered serendipitously. PMID:27403616

  8. Remodeling of Glucose Metabolism Precedes Pressure Overload -Induced Left Ventricular Hypertrophy: Review of a Hypothesis

    PubMed Central

    Kundu, Bijoy K.; Zhong, Min; Sen, Shiraj; Davogustto, Giovanni; Keller, Susanna R.; Taegtmeyer, Heinrich

    2015-01-01

    When subjected to pressure overload, the ventricular myocardium shifts from fatty acids to glucose as its main source for energy provision and frequently increases its mass. Here, we review the evidence in support of the concept that metabolic remodeling, measured as increased myocardial glucose uptake using dynamic positron emission tomography (PET) with the glucose analogue 2-deoxy-2-[18F]-fluoro-D-glucose (FDG), precedes the onset of left ventricular hypertrophy (LVH) and heart failure. Consistent with this, early intervention with propranolol, which attenuates glucose uptake, prevents the maladaptive metabolic response and preserves cardiac function in vivo. We also review ex vivo studies suggesting a link between dysregulated myocardial glucose metabolism, intracellular accumulation of glucose 6-phosphate (G6P) and contractile dysfunction of the heart. G6P levels correlate with activation of mTOR (mechanistic target of rapamycin) and endoplasmic reticulum stress. This sequence of events could be prevented by pre-treatment with rapamycin (mTOR inhibition) or metformin (enzyme 5′-AMP-activated protein kinase activation ). In conclusion, we propose that metabolic imaging with FDG PET may provide a novel approach to guide the treatment of patients with hypertension-induced LVH. PMID:25791172

  9. Targeted Recycling of the Lateral Border Recycling Compartment Precedes Adherens Junction Dissociation during Transendothelial Migration.

    PubMed

    Gonzalez, Annette M; Cyrus, Bita F; Muller, William A

    2016-05-01

    Leukocyte transendothelial migration (TEM) requires two major events: local dissociation of adherens junctions manifested as gaps in vascular endothelial (VE)-cadherin staining at the site of TEM and targeted trafficking of the lateral border recycling compartment (LBRC) to the site of TEM. However, the association between LBRC recycling and VE-cadherin gaps remains unknown. We found that when targeting of the LBRC is selectively inhibited using established methods, such as a function blocking anti-platelet endothelial cell adhesion molecule 1 antibody, depolymerizing microtubules, or microinjection of an antibody that inhibits kinesin, VE-cadherin gaps do not form around the blocked leukocyte. This is the first time that the LBRC has been implicated in this process. We obtained similar results for neutrophils and monocytes and in studies using live cell imaging microscopy conducted under fluid shear conditions. Depolymerizing microtubules did not affect the ability of leukocytes to induce tyrosine phosphorylation of VE-cadherin. A VE-cadherin double mutant (Y658F, Y731F) expressed in endothelial cells acted as a dominant negative and inhibited VE-cadherin gap formation and TEM, yet targeting of the LBRC still occurred. These data suggest that targeting of the LBRC to the site of TEM precedes VE-cadherin clearance. Recruitment of the LBRC may play a role in clearing VE-cadherin from the site of TEM. PMID:26968345

  10. Circulating calcium concentrations, vascular disease and mortality: a systematic review.

    PubMed

    Reid, I R; Gamble, G D; Bolland, M J

    2016-06-01

    Associations between serum calcium and vascular disease have been reported, but the consistency of these findings is unknown. We conducted a systematic review to determine whether circulating calcium concentrations are associated with risks of cardiovascular disease and death in normocalcaemic populations. We conducted PubMed searches up to 18 December 2014 and scrutinized reference lists of papers. Eligible studies related serum calcium to mortality or cardiovascular events in humans. A follow-up of at least one year was required for longitudinal studies. Studies in populations selected on the basis of renal disease or abnormal serum calcium were excluded. Two investigators performed independent data extraction. The results were tabulated and, where possible, meta-analysed. Five of 11 studies reported a statistically significant positive association between serum calcium and mortality. Meta-analysis of eight of these studies showed a hazard ratio of death of 1.13 (1.09, 1.18) per standard deviation of serum calcium. Eight of 13 studies reported a statistically significant positive association between serum calcium and cardiovascular disease. Meta-analysis of eight studies showed a hazard ratio of cardiovascular disease of 1.08 (1.04, 1.13) per standard deviation of serum calcium. For two studies reporting odds ratios, the pooled odds ratio per standard deviation was 1.22 (1.11, 1.32). When hazard ratios adjusted for cardiovascular risk factors were meta-analysed, the pooled hazard ratio was 1.04 (1.01, 1.08). Other studies demonstrated associations between serum calcium and stroke and between serum calcium and direct measurements of arterial disease and calcification. These observational data indicate that serum calcium is associated with vascular disease and death, but they cannot determine causality. PMID:26749423

  11. 42 CFR 405.850 - Change of ruling or legal precedent.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 42 Public Health 2 2010-10-01 2010-10-01 false Change of ruling or legal precedent. 405.850... Part B Program § 405.850 Change of ruling or legal precedent. Change of a legal interpretation or administrative ruling upon which a determination or decision was made shall not be considered as good...

  12. Reiter's disease: Circinate balanitis as alone preceding presentation - Successfully treated with pimecrolimus 1% cream.

    PubMed

    Kumar, Sumir; Mahajan, Bharat Bhushan; Ahluwalia, Ravinder Singh; Boparai, Amarbir Singh

    2015-01-01

    Circinate balanitis, although a common manifestation of reactive arthritis, is usually an associated finding present along with the triad of arthritis, conjunctivitis, and urethritis. It is rarely seen as the only preceding manifestation of reactive arthritis. We hereby report a case of circinate balanitis as alone preceding presentation of reactive arthritis that was successfully treated with topical pimecrolimus 1% cream. PMID:26392659

  13. 7 CFR 1779.63 - Conditions precedent to issuance of the Loan Note Guarantee.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 12 2011-01-01 2011-01-01 false Conditions precedent to issuance of the Loan Note Guarantee. 1779.63 Section 1779.63 Agriculture Regulations of the Department of Agriculture (Continued) RURAL UTILITIES SERVICE, DEPARTMENT OF AGRICULTURE (CONTINUED) WATER AND WASTE DISPOSAL PROGRAMS GUARANTEED LOANS § 1779.63 Conditions precedent...

  14. 48 CFR 1211.101 - Order of precedence for requirements documents.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 48 Federal Acquisition Regulations System 5 2014-10-01 2014-10-01 false Order of precedence for requirements documents. 1211.101 Section 1211.101 Federal Acquisition Regulations System DEPARTMENT OF TRANSPORTATION ACQUISITION PLANNING DESCRIBING AGENCY NEEDS Selecting and Developing Requirements Documents 1211.101 Order of precedence...

  15. 48 CFR 1480.502 - Order of precedence for use of Government supply sources.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 48 Federal Acquisition Regulations System 5 2014-10-01 2014-10-01 false Order of precedence for use of Government supply sources. 1480.502 Section 1480.502 Federal Acquisition Regulations System DEPARTMENT OF THE INTERIOR INDIAN AFFAIRS SUPPLEMENT ACQUISITIONS UNDER THE BUY INDIAN ACT Procedures 1480.502 Order of precedence for use of...

  16. 26 CFR 1.665(e)-1A - Preceding taxable year.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 26 Internal Revenue 8 2011-04-01 2011-04-01 false Preceding taxable year. 1.665(e)-1A Section 1... (CONTINUED) INCOME TAXES (CONTINUED) Treatment of Excess Distributions of Trusts Applicable to Taxable Years Beginning on Or After January 1, 1969 § 1.665(e)-1A Preceding taxable year. (a) Definition—(1)...

  17. 26 CFR 1.665(e)-1A - Preceding taxable year.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 26 Internal Revenue 8 2010-04-01 2010-04-01 false Preceding taxable year. 1.665(e)-1A Section 1... (CONTINUED) INCOME TAXES Treatment of Excess Distributions of Trusts Applicable to Taxable Years Beginning on Or After January 1, 1969 § 1.665(e)-1A Preceding taxable year. (a) Definition—(1) Domestic...

  18. Growth and yield of winter wheat as affected by preceding crop and crop management

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Producers in eastern South Dakota are interested in adding winter wheat (Triticum aestivum L.) to the corn (Zea mays L.)-soybean (Glycine max Merrill) rotation to improve crop yield and pest management. Our study quantified winter wheat response to preceding crop and crop management. Preceding cro...

  19. 26 CFR 1.665(e)-1A - Preceding taxable year.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 26 Internal Revenue 8 2012-04-01 2012-04-01 false Preceding taxable year. 1.665(e)-1A Section 1... (CONTINUED) INCOME TAXES (CONTINUED) Treatment of Excess Distributions of Trusts Applicable to Taxable Years Beginning on Or After January 1, 1969 § 1.665(e)-1A Preceding taxable year. (a) Definition—(1)...

  20. 26 CFR 1.665(e)-1A - Preceding taxable year.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 26 Internal Revenue 8 2014-04-01 2014-04-01 false Preceding taxable year. 1.665(e)-1A Section 1... (CONTINUED) INCOME TAXES (CONTINUED) Treatment of Excess Distributions of Trusts Applicable to Taxable Years Beginning on Or After January 1, 1969 § 1.665(e)-1A Preceding taxable year. (a) Definition—(1)...

  1. Modelling of calcium phosphates

    NASA Astrophysics Data System (ADS)

    Calderin Hidalgo, Lazaro Juan

    This work is a contribution to a large scale joint experimental and theoretical effort to understand the biological properties of silicon doped calcium phosphates undertaken by Queen's University and Millenium Biologix Corp. We have modeled calcium phosphates and silicon doped calcium phosphates in close relation to experiment in order to study possible location of silicon in the lattice. Density functional theory has been used to study the structural and dynamical properties of small systems of calcium phosphates to gain preliminary information on phosphates and the performance of the theoretical methods. The same methods were used to investigate structural and electronic properties of larger scale calcium phosphate systems, while a classical shell model was developed to investigate the dynamical properties of such large and complex systems. In the context of the shell model a method was devised to calculate the dynamical matrix corrected for the long range Coulomb interaction in the long wave length limit. It was necessary also to develop a theoretical expression for the dielectric function in the context of the shell model. Infrared spectra and thermal parameters were calculated based on these methods. We also propose some directions for future research.

  2. Role of calcium in growth inhibition induced by a novel cell surface sialoglycopeptide

    NASA Technical Reports Server (NTRS)

    Betz, N. A.; Westhoff, B. A.; Johnson, T. C.; Spooner, B. S. (Principal Investigator)

    1995-01-01

    Our laboratory has purified an 18 kDa cell surface sialoglycopeptide growth inhibitor (CeReS-18) from intact bovine cerebral cortex cells. Evidence presented here demonstrates that sensitivity to CeReS-18-induced growth inhibition in BALB-c 3T3 cells is influenced by calcium, such that a decrease in the calcium concentration in the growth medium results in an increase in sensitivity to CeReS-18. Calcium did not alter CeReS-18 binding to its cell surface receptor and CeReS-18 does not bind calcium directly. Addition of calcium, but not magnesium, to CeReS-18-inhibited 3T3 cells results in reentry into the cell cycle. A greater than 3-hour exposure to increased calcium is required for escape from CeReS-18-induced growth inhibition. The calcium ionophore ionomycin could partially mimic the effect of increasing extracellular calcium, but thapsigargin was ineffective in inducing escape from growth inhibition. Increasing extracellular calcium 10-fold resulted in an approximately 7-fold increase in total cell-associated 45Ca+2, while free intracellular calcium only increased approximately 30%. However, addition of CeReS-18 did not affect total cell-associated calcium or the increase in total cell-associated calcium observed with an increase in extracellular calcium. Serum addition induced mobilization of intracellular calcium and influx across the plasma membrane in 3T3 cells, and pretreatment of 3T3 cells with CeReS-18 appeared to inhibit these calcium mobilization events. These results suggest that a calcium-sensitive step exists in the recovery from CeReS-18-induced growth inhibition. CeReS-18 may inhibit cell proliferation through a novel mechanism involving altering the intracellular calcium mobilization/regulation necessary for cell cycle progression.

  3. Detection and analysis of precursor magnetic preceding the Turkey and Greek seismicity

    NASA Astrophysics Data System (ADS)

    van Bise, W.; Rauscher, E. A.

    2003-04-01

    We have conducted extensive measurements, precursor analysis and predictions of seismic events from twenty one laboratory sites in the United States and Canada over the last twenty three years. Both local (a few Km) and long range (over 5,000 Km) precursor site recordings and subsequent seismic events have been made and statistically analyzed. Our measurement detection and analysis system records local and ionospherically transmitted long range signals. We measure vertical and horizontal magnetic field components from ground based systems in the range of .001 to 25 Hz at a sensitivity of 10-6 to 10-7 Gauss. We also utilize an electric field antenna. Ground and ionospheric excitations are recorded. In the fall of 1999, significant seismic occurrences took place in the Greek-Turkey region. We recorded precursor signatures and registered five predictions with the Research Recording Division of the U.S. Library of Congress and other international geophysical research groups, including the U.N. Hazard Reduction Program. Precursor signatures were recorded 12 to 72 hours preceding the seismic event. No false positives or false negatives were make during this period for this region. Statistical analysis will be presented. See the table. Successful Long Range, Short Lead Time Prediction Correlated with the Following Seismic Event Prediction Dominate Seismic Occurrence Lead Approximate Precursor Approximate Time (hr) Location Frequencies Magnitude Date Location Magnitude (Hz) 48-72 Greek-Turkey 3.22, 3.61 7.6+ Aug 25 SE Istanbul Turkey 7.4 Region 7.23 12 Greece 3.35, 6.61 6 < M < 7 Sept. 6 N. Athens Greece 5.9 11.9 24 Turkey 3.35, 3.71 6 < M < 7 Sept. 9 Istanbul Turkey 6.5 6.35, 7.32 12-15 Turkey 3.61, 6.25 5.5 < M < 6.5 Sept. 13 Izmit Turkey 5.8 7.23 36 Turkey 3.61 7 < M < 8 Nov. 12 E. Istanbul Turkey 7.2

  4. Behaviour patterns preceding a railway suicide: Explorative study of German Federal Police officers' experiences

    PubMed Central

    2011-01-01

    Background Constant high-level numbers of railway suicides indicate that prevention strategies against railway suicides are urgently needed. The main question of the present study was whether pre-crash railway suicide behaviour can be identified, using German Federal Police officers experience with suicidal events in railway related environments. Methods To collect information on pre-crash railway suicide behaviour, a questionnaire was used and made available on the German Federal Police intranet. A total of 202 subjects (mean age: 41 years, sex: 84.9% male) were included in the analysis. Multivariate logistic regression analyses were performed to predict the prevention of suicide (first model) or demand for counselling (second model) as outcomes. Sex, age, years of service, number of experienced suicides, suicides personally observed, information on suicides obtained from witnesses and finally either counselling/debriefing (first model) or whether officers had prevented a suicide (second model) were used as predictors. Results A considerable proportion of police officers reported behavioural patterns preceding a suicide. Half of them observed the dropping or leaving behind of personal belongings or the avoidance of eye contact, more than a third erratic gesture, mimic or movement. Erratic communication patterns and general confusion were each reported by about one quarter. One fifth indicated the influence of alcohol. Less frequently observed behaviour was aimlessly wandering (14.3%) and out of the ordinary clothing (4%). About one third of all railway suicide victims committed suicide in stations. Of those, 70% had chosen an eminent spot. The multivariate logistic regression model using prevented suicides as the outcome identified the number of suicides experienced, counselling/debriefing and having personally observed a suicide as variables with significant impact. The model using counselling/debriefing as the outcome identified age and having prevented a

  5. Predictability of Rogue Events

    NASA Astrophysics Data System (ADS)

    Birkholz, Simon; Brée, Carsten; Demircan, Ayhan; Steinmeyer, Günter

    2015-05-01

    Using experimental data from three different rogue wave supporting systems, determinism, and predictability of the underlying dynamics are evaluated with methods of nonlinear time series analysis. We included original records from the Draupner platform in the North Sea as well as time series from two optical systems in our analysis. One of the latter was measured in the infrared tail of optical fiber supercontinua, the other in the fluence profiles of multifilaments. All three data sets exhibit extreme-value statistics and exceed the significant wave height in the respective system by a factor larger than 2. Nonlinear time series analysis indicates a different degree of determinism in the systems. The optical fiber scenario is found to be driven by quantum noise whereas rogue waves emerge as a consequence of turbulence in the others. With the large number of rogue events observed in the multifilament system, we can systematically explore the predictability of such events in a turbulent system. We observe that rogue events do not necessarily appear without a warning, but are often preceded by a short phase of relative order. This surprising finding sheds some new light on the fascinating phenomenon of rogue waves.

  6. Gravimetric Determination of Calcium as Calcium Carbonate Hydrate.

    ERIC Educational Resources Information Center

    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)

  7. [Mitochondria, calcium homeostasis and calcium signaling].

    PubMed

    Zavodnik, I B

    2016-03-01

    Са2+ is a very important and versatile intracellular signal which controls numerous biochemical and physiological (pathophysiological) processes in the cell. Good evidence exists that mitochondria are sensors, decoders and regulators of calcium signaling. Precise regulation of calcium signaling in the cell involves numerous molecular targets, which induce and decode changes of Са2+ concentrations in the cell (pumps, channels, Са2+-binding proteins, Са2+-dependent enzymes, localized in the cytoplasm and organelles). Mitochondrial Са2+ uniporter accumulates excess of Са2+ in mitochondria, while Na+/Са2+- and H+/Са2+-antiporters extrude Са2+ in the cytoplasm. Mitochondrial Са2+ overloading results in formation of mitochondria permeability transition pores which play an important role in cell death under many pathological conditions. Mitochondria regulate Са2+ homeostasis and control important cellular functions such as metabolism, proliferation, survival. Identification of cellular and mitochondrial Ca2+ transporters and understanding their functional mechanisms open up new prospects for their using as therapeutic targets. PMID:27420625

  8. Calcium and olfactory transduction.

    PubMed

    Winegar, B D; Rosick, E R; Schafer, R

    1988-01-01

    1. Inorganic cations, organic calcium antagonists, and calmodulin antagonists were applied to olfactory epithelia of frogs (Rana pipiens) while recording electroolfactogram (EOG) responses. 2. Inorganic cations inhibited EOGs in a rank order, reflecting their calcium channel blocking potency: La3+ greater than Zn2+ greater than Cd2+ greater than Al3+ greater than Ca2+ greater than Sr2+ greater than Co2+ greater than Ba2+ greater than Mg2+. Barium ion significantly enhanced EOGs immediately following application. 3. Diltiazem and verapamil produced dose-dependent EOG inhibition. 4. Calmodulin antagonists inhibited EOGs without correlation to their anti-calmodulin potency. PMID:2904344

  9. Calcium metabolism in microgravity.

    PubMed

    Heer, M; Kamps, N; Biener, C; Korr, C; Boerger, A; Zittermann, A; Stehle, P; Drummer, C

    1999-09-01

    Unloading of weight bearing bones as induced by microgravity or immobilization has significant impacts on the calcium and bone metabolism and is the most likely cause for space osteoporosis. During a 4.5 to 6 month stay in space most of the astronauts develop a reduction in bone mineral density in spine, femoral neck, trochanter, and pelvis of 1%-1.6% measured by Dual Energy X-ray Absorption (DEXA). Dependent on the mission length and the individual turnover rates of the astronauts it can even reach individual losses of up to 14% in the femoral neck. Osteoporosis itself is defined as the deterioration of bone tissue leading to enhanced bone fragility and to a consequent increase in fracture risk. Thinking of long-term missions to Mars or interplanetary missions for years, space osteoporosis is one of the major concerns for manned spaceflight. However, decrease in bone density can be initiated differently. It either can be caused by increases in bone formation and bone resorption resulting in a net bone loss, as obtained in fast looser postmenopausal osteoporosis. On the other hand decrease in bone formation and increase in bone resorption also leads to bone losses as obtained in slow looser postmenopausal osteoporosis or in Anorexia Nervosa patients. Biomarkers of bone turnover measured during several missions indicated that the pattern of space osteoporosis is very similar to the pattern of Anorexia Nervosa patients or slow looser postmenopausal osteoporosis. However, beside unloading, other risk factors for space osteoporosis exist such as stress, nutrition, fluid shifts, dehydration and bone perfusion. Especially nutritional factors may contribute considerably to the development of osteoporosis. From earthbound studies it is known that calcium supplementation in women and men can prevent bone loss of 1% bone per year. Based on these results we studied the calcium intake during several European missions and performed an experiment during the German MIR 97 mission

  10. Accumulation of calcium and loss of potassium in the hippocampus following transient cerebral ischemia: a proton microprobe study

    SciTech Connect

    Martins, E.; Inamura, K.; Themner, K.; Malmqvist, K.G.; Siesjoe, B.K.

    1988-08-01

    This study explored (a) whether postischemic accumulation of calcium in hippocampal neurons precedes or occurs pari passu with light microscopical signs of delayed neuronal necrosis, and (b) whether calcium initially accumulates in dendritic domains, presumed to have a high density of agonist-operated calcium channels. Transient ischemia of 10-min duration was induced in rats, and the animals were studied after 1, 2, 3, and 4 days of recovery. We measured total calcium and potassium contents in the stratum oriens, pyramidale, radiatum, and moleculare of the CA1 and CA3 sectors, using particle induced x-ray emission (PIXE) in the proton microprobe mode. The results showed significant accumulation of calcium and loss of potassium after 3 and 4 days of recovery in the CA1 sector, which developed neuronal necrosis, but not in the CA3 sector, which showed only occasional damage. In a few animals, calcium accumulation (and loss of potassium) was observed with no or only mild visible damage, but in the majority of animals the accumulation of calcium correlated to signs of neuronal necrosis. Since calcium accumulation was similar in all strata examined, the results failed to reveal preferential accumulation in dendritic or somal regions. Based on our results and those of Dux et al., we emphasize the possibility that delayed neuronal death is, at least in part, caused by increased calcium cycling of plasma membranes and gradual calcium overload of mitochondria.